NUREG-1937, Vol. 1

Environmental Impact Statement for 

Combined Licenses (COLs) for 

South Texas Project Electric 

Generating Station Units 3 and 4 

Final Report 

U.S. Nuclear Regulatory Commission 

Office of New Reactors 

Washington, DC 20555-0001 

U.S. Army Corps of Engineers 

U.S. Army Engineer District, Galveston 

Galveston, TX 77553-1229 
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Environmental Impact Statement for 

Combined Licenses (COLs) for 

South Texas Project Electric 

Generating Station Units 3 and 4

Final Report 

Manuscript Completed: February 2011 

Date Published: February 2011 

Division of Site and Environmental Review 

Office of New Reactors 

U.S. Nuclear Regulatory Commission 

Washington, DC 20555-0001 

Regulatory Branch 

Planning, Environmental and Regulatory Division 

U.S. Army Engineer District, Galveston 

U.S. Army Corps of Engineers 

Galveston, Texas 77553-1229 

 NUREG-1937, Vol. 1 

February 2011 iii NUREG-1937 

Abstract 

This environmental impact statement (EIS) has been prepared in response to an application 

submitted to the U.S. Nuclear Regulatory Commission (NRC) by STP Nuclear Operating 

Company (STPNOC) for combined construction permits and operating licenses (combined 

licenses or COLs). The proposed actions related to the STPNOC application are (1) NRC 

issuance of COLs for two new nuclear power reactor units at the South Texas Project Electric 

Generating Station (STP) site in Matagorda County, Texas, and (2) U.S. Army Corps of 

Engineers (Corps) issuance of a permit to perform certain construction activities on the site. 

The Corps is participating in preparing this EIS as a cooperating agency and participates 

collaboratively on the review team. 

This EIS includes the review team’s analysis that considers and weighs the environmental 

impacts of building and operating two new nuclear units at the STP site and at alternative sites, 

and mitigation measures available for reducing or avoiding adverse impacts. 

The EIS includes the evaluation of the proposed action’s impacts to waters of the United States 

pursuant to Section 404 of the Federal Water Pollution Control Act (Clean Water Act) and 

Section 10 of the Rivers and Harbors Appropriation Act of 1899. The Corps will conduct a public 

interest review in accordance with the guidelines promulgated by the U.S. Environmental 

Protection Agency under authority of Section 404(b) of the Clean Water Act. The public interest 

review, which will be addressed in the Corps’ permit decision document, will include an 

alternatives analysis to determine the Least Environmentally Damaging Practicable Alternative. 

After considering the environmental aspects of the proposed action, the NRC staff’s 

recommendation to the Commission is that the COLs be issued as proposed. This 

recommendation is based on (1) the application, including the Environmental Report (ER), 

submitted by STPNOC; (2) consultation with Federal, State, Tribal, and local agencies; (3) the 

review team’s independent review; (4) the consideration of public comments; and (5) the 

assessments summarized in this EIS, including the potential mitigation measures identified in 

the ER and in this EIS. The Corps will issue its Record of Decision based, in part, on this EIS. 

February 2011 v NUREG-1937 

Contents 

Abstract ......................................................................................................................................... iii

Executive Summary .................................................................................................................. xxix

Abbreviations/Acronyms ......................................................................................................... xxxiii

1.0 Introduction ....................................................................................................................... 1-1

1.1 Background .............................................................................................................. 1-2

1.1.1 Application and Review ................................................................................ 1-2

1.1.1.1 NRC COL Application Review ....................................................... 1-3

1.1.1.2 Corps Permit Application Review................................................... 1-4

1.1.2 Preconstruction Activities ............................................................................. 1-5

1.1.3 Cooperating Agencies .................................................................................. 1-6

1.1.4 Concurrent NRC Reviews ............................................................................ 1-7

1.2 The Proposed Federal Actions ................................................................................. 1-8

1.3 The Purpose and Need for the Proposed Actions .................................................... 1-9

1.4 Alternatives to the Proposed Actions ....................................................................... 1-9

1.5 Compliance and Consultations ............................................................................... 1-10

1.6 References ............................................................................................................. 1-10

2.0 Affected Environment ....................................................................................................... 2-1

2.1 Site Location ............................................................................................................. 2-1

2.2 Land Use .................................................................................................................. 2-1

2.2.1 The Site and Vicinity ..................................................................................... 2-1

2.2.2 Transmission Lines ....................................................................................... 2-9

2.2.3 The Region ................................................................................................... 2-9

2.3 Water ...................................................................................................................... 2-11

2.3.1 Hydrology ................................................................................................... 2-11

2.3.1.1 Surface-Water Hydrology ............................................................ 2-11

2.3.1.2 Groundwater Hydrology ............................................................... 2-22

2.3.2 Water Use ................................................................................................... 2-33

2.3.2.1 Surface-Water Use ...................................................................... 2-34

2.3.2.2 Groundwater Use ......................................................................... 2-36

2.3.3 Water Quality .............................................................................................. 2-40

2.3.3.1 Surface-Water Quality ................................................................. 2-40

2.3.3.2 Groundwater Quality .................................................................... 2-42
NUREG-1937 vi February 2011 

2.3.4 Water Monitoring ........................................................................................ 2-44

2.3.4.1 Surface-Water Monitoring ............................................................ 2-44

2.3.4.2 Groundwater Monitoring .............................................................. 2-46

2.4 Ecology ................................................................................................................... 2-48

2.4.1 Terrestrial Ecology ...................................................................................... 2-48

2.4.1.1 Terrestrial Communities of the Site and Vicinity .......................... 2-48

2.4.1.2 Terrestrial Resources – Transmission Lines ................................ 2-56

2.4.1.3 Important Terrestrial Species and Habitats .................................. 2-57

2.4.1.4 Terrestrial Ecology Monitoring ..................................................... 2-67

2.4.2 Aquatic Ecology .......................................................................................... 2-67

2.4.2.1 Aquatic Resources of the Site and Vicinity .................................. 2-67

2.4.2.2 Aquatic Resources – Transmission Lines .................................... 2-88

2.4.2.3 Important Aquatic Species and Habitats ...................................... 2-88

2.4.2.4 Aquatic Monitoring ..................................................................... 2-108

2.5 Socioeconomics ................................................................................................... 2-109

2.5.1 Demographics .......................................................................................... 2-111

2.5.1.1 Resident Population ................................................................... 2-112

2.5.1.2 Transient Population .................................................................. 2-115

2.5.1.3 Migrant Labor ............................................................................. 2-116

2.5.2 Community Characteristics ....................................................................... 2-117

2.5.2.1 Economy .................................................................................... 2-118

2.5.2.2 Taxes ......................................................................................... 2-121

2.5.2.3 Transportation ............................................................................ 2-127

2.5.2.4 Aesthetics and Recreation ......................................................... 2-130

2.5.2.5 Housing ...................................................................................... 2-132

2.5.2.6 Public Services .......................................................................... 2-134

2.6 Environmental Justice .......................................................................................... 2-146

2.6.1 Methodology ............................................................................................. 2-147

2.6.2 Scoping and Outreach .............................................................................. 2-153

2.6.3 Subsistence and Communities with Unique Characteristics .................... 2-153

2.6.4 Migrant Populations .................................................................................. 2-155

2.6.5 Environmental Justice Summary .............................................................. 2-155

2.7 Historic and Cultural Resources ........................................................................... 2-156

2.7.1 Cultural Background ................................................................................. 2-156

2.7.2 Historic and Cultural Resources at the Site .............................................. 2-157

2.7.3 Consultation .............................................................................................. 2-159
February 2011 vii NUREG-1937 

2.8 Geology ................................................................................................................ 2-160

2.9 Meteorology and Air Quality ................................................................................. 2-161

2.9.1 Climate ..................................................................................................... 2-161

2.9.1.1 Wind ........................................................................................... 2-163

2.9.1.2 Temperature .............................................................................. 2-163

2.9.1.3 Atmospheric Moisture ................................................................ 2-163

2.9.1.4 Severe Weather ......................................................................... 2-164

2.9.1.5 Atmospheric Stability ................................................................. 2-164

2.9.2 Air Quality ................................................................................................. 2-165

2.9.3 Atmospheric Dispersion ............................................................................ 2-165

2.9.3.1 Short-Term Dispersion Estimates .............................................. 2-166

2.9.3.2 Long-Term Dispersion Estimates............................................... 2-167

2.9.4 Meteorological Monitoring ........................................................................ 2-167

2.10 Nonradiological Health ......................................................................................... 2-168

2.10.1 Public and Occupational Health ............................................................... 2-168

2.10.1.1 Air Quality .................................................................................. 2-168

2.10.1.2 Occupational Injuries ................................................................. 2-169

2.10.1.3 Etiological Agents ...................................................................... 2-170

2.10.2 Noise ........................................................................................................ 2-171

2.10.3 Transportation .......................................................................................... 2-172

2.10.4 Electromagnetic Fields ............................................................................. 2-172

2.11 Radiological Environment ..................................................................................... 2-173

2.12 Related Federal Projects and Consultation .......................................................... 2-174

2.13 References ........................................................................................................... 2-174

3.0 Site Layout and Plant Description .................................................................................... 3-1

3.1 External Appearance and Plant Layout .................................................................... 3-1

3.2 Proposed Plant Structures, Systems, and Components .......................................... 3-2

3.2.1 Reactor Power Conversion System .............................................................. 3-2

3.2.2 Structures, Systems, and Components with a Major Environmental 

Interface ........................................................................................................ 3-3

3.2.2.1 Landscape and Stormwater Drainage ........................................... 3-6

3.2.2.2 Cooling Water System ................................................................... 3-6

3.2.2.3 Other Permanent Plant-Environment Interfacing Structures, 

Systems, or Components .............................................................. 3-9

3.2.2.4 Other Temporary Plant-Environment Interfacing Structures ........ 3-11

3.2.3 Structures with a Minor Environmental Interface ........................................ 3-11
NUREG-1937 viii February 2011 

3.3 Construction and Preconstruction Activities ........................................................... 3-13

3.3.1 Major Activity Areas .................................................................................... 3-13

3.3.2 Summary of Resource Commitments During Construction and 

Preconstruction ........................................................................................... 3-17

3.4 Operational Activities .............................................................................................. 3-17

3.4.1 Description of Operational Modes .............................................................. 3-18

3.4.2 Plant-Environment Interfaces During Operation ......................................... 3-18

3.4.2.1 Circulating Water System – Intakes, Discharges, Cooling 

Towers ......................................................................................... 3-19

3.4.2.2 Landscape and Drainage ............................................................. 3-19

3.4.2.3 Essential Service Water System – Ultimate Heat Sink ................ 3-19

3.4.2.4 Emergency Diesel Generators ..................................................... 3-20

3.4.3 Radioactive Waste-Management System .................................................. 3-20

3.4.3.1 Liquid Radioactive Waste-Management System ......................... 3-21

3.4.3.2 Gaseous Waste-Management System ........................................ 3-21

3.4.3.3 Solid Radioactive Waste-Management System ........................... 3-22

3.4.4 Nonradioactive Waste-Management Systems ........................................... 3-23

3.4.4.1 Solid Waste Management ............................................................ 3-23

3.4.4.2 Liquid Waste Management .......................................................... 3-23

3.4.4.3 Gaseous Waste Management ..................................................... 3-25

3.4.4.4 Hazardous and Mixed Waste Management ................................. 3-25

3.4.5 Summary of Resource Parameters During Operation ................................ 3-25

3.5 References ............................................................................................................. 3-27

4.0 Construction Impacts at the Proposed Site ...................................................................... 4-1

4.1 Land-Use Impacts .................................................................................................... 4-4

4.1.1 The Site ........................................................................................................ 4-4

4.1.2 Transmission Line Corridors and Offsite Areas ............................................ 4-5

4.2 Water-Related Impacts ............................................................................................. 4-6

4.2.1 Hydrological Alterations ................................................................................ 4-7

4.2.2 Water-Use Impacts ....................................................................................... 4-8

4.2.3 Water-Quality Impacts ................................................................................ 4-11

4.2.3.1 Surface-Water Quality Impacts .................................................... 4-12

4.2.3.2 Groundwater-Quality Impacts ...................................................... 4-12

4.2.4 Water Monitoring ........................................................................................ 4-14

4.3 Ecological Impacts ................................................................................................. 4-14

4.3.1 Terrestrial and Wetland Impacts ................................................................. 4-15
February 2011 ix NUREG-1937 

4.3.1.1 Impacts to Terrestrial Resources – Site and Vicinity ................... 4-15

4.3.1.2 Terrestrial Resources – Transmission Line Corridors .................. 4-18

4.3.1.3 Important Terrestrial Species and Habitats .................................. 4-20

4.3.1.4 Terrestrial Monitoring ................................................................... 4-24

4.3.1.5 Summary of Impacts to Terrestrial Resources ............................. 4-25

4.3.2 Aquatic Impacts .......................................................................................... 4-26

4.3.2.1 Aquatic Resources – Site and Vicinity ......................................... 4-27

4.3.2.2 Aquatic Resources –Transmission Line Corridors ....................... 4-30

4.3.2.3 Important Aquatic Species and Habitats ...................................... 4-31

4.3.2.4 Aquatic Monitoring ....................................................................... 4-36

4.3.2.5 Potential Mitigation Measures for Aquatic Impacts ...................... 4-37

4.3.2.6 Summary of Impacts to Aquatic Resources ................................. 4-37

4.4 Socioeconomic Impacts ......................................................................................... 4-38

4.4.1 Physical Impacts ......................................................................................... 4-38

4.4.1.1 Workers and the Local Public ...................................................... 4-38

4.4.1.2 Buildings ...................................................................................... 4-39

4.4.1.3 Roads .......................................................................................... 4-39

4.4.1.4 Aesthetics .................................................................................... 4-40

4.4.1.5 Summary of Physical Impacts ...................................................... 4-40

4.4.2 Demography ............................................................................................... 4-40

4.4.3 Economic Impacts to the Community ......................................................... 4-42

4.4.3.1 Economy ...................................................................................... 4-43

4.4.3.2 Taxes ........................................................................................... 4-44

4.4.3.3 Summary of Economic Impacts to the Community ...................... 4-46

4.4.4 Infrastructure and Community Service Impacts .......................................... 4-46

4.4.4.1 Transportation .............................................................................. 4-46

4.4.4.2 Recreation ................................................................................... 4-49

4.4.4.3 Housing ........................................................................................ 4-49

4.4.4.4 Public Services ............................................................................ 4-50

4.4.4.5 Education ..................................................................................... 4-53

4.4.4.6 Summary of Community Service and Infrastructure Impacts ....... 4-53

4.4.5 Summary of Socioeconomic Impacts ......................................................... 4-54

4.5 Environmental Justice Impacts ............................................................................... 4-55

4.5.1 Analytical Considerations ........................................................................... 4-55

4.5.2 Health Impacts ............................................................................................ 4-55

4.5.3 Physical and Environmental Impacts .......................................................... 4-57

4.5.3.1 Soil ............................................................................................... 4-57

4.5.3.2 Water ........................................................................................... 4-57
NUREG-1937 x February 2011 

4.5.3.3 Air ................................................................................................ 4-58

4.5.3.4 Noise ............................................................................................ 4-58

4.5.3.5 Summary of Physical and Environmental Impacts ....................... 4-58

4.5.4 Socioeconomic Impacts .............................................................................. 4-58

4.5.5 Subsistence and Special Conditions .......................................................... 4-59

4.5.5.1 Subsistence ................................................................................. 4-59

4.5.5.2 High-Density Communities .......................................................... 4-60

4.5.6 Summary of Environmental Justice Impacts .............................................. 4-61

4.6 Historic and Cultural Resources ............................................................................. 4-61

4.7 Meteorological and Air-Quality Impacts .................................................................. 4-63

4.7.1 Construction and Preconstruction Activities ............................................... 4-63

4.7.2 Traffic .......................................................................................................... 4-64

4.7.3 Summary .................................................................................................... 4-66

4.8 Nonradiological Health Impacts .............................................................................. 4-65

4.8.1 Public and Occupational Health ................................................................. 4-66

4.8.1.1 Public Health ................................................................................ 4-66

4.8.1.2 Construction Worker Health ......................................................... 4-67

4.8.1.3 Summary of Public and Construction Worker Health Impacts ..... 4-68

4.8.2 Noise Impacts ............................................................................................. 4-68

4.8.3 Impacts of Transporting Construction Materials and Construction 

Personnel to the STP Site .......................................................................... 4-69

4.8.4 Summary of Nonradiological Health Impacts ............................................. 4-72

4.9 Radiological Health Impacts ................................................................................... 4-72

4.9.1 Direct Radiation Exposures ........................................................................ 4-72

4.9.2 Radiation Exposures from Gaseous Effluents ............................................ 4-73

4.9.3 Radiation Exposures from Liquid Effluents ................................................. 4-74

4.9.4 Total Dose to Construction Workers ........................................................... 4-74

4.9.5 Summary of Radiological Health Impacts ................................................... 4-74

4.10 Nonradioactive Waste Impacts ............................................................................... 4-75

4.10.1 Impacts to Land .......................................................................................... 4-75

4.10.2 Impacts to Water ........................................................................................ 4-76

4.10.3 Impacts to Air .............................................................................................. 4-76

4.10.4 Summary of Impacts ................................................................................... 4-77
February 2011 xi NUREG-1937 

4.11 Measures and Controls to Limit Adverse Impacts During Construction 

Activities ................................................................................................................. 4-77

4.12 Summary of Preconstruction and Construction Impacts ........................................ 4-78

4.13 References ............................................................................................................. 4-88

5.0 Operational Impacts at the Proposed Site ........................................................................ 5-1

5.1 Land-Use Impacts .................................................................................................... 5-1

5.1.1 The Site ........................................................................................................ 5-2

5.1.2 Transmission Corridors and Offsite Areas .................................................... 5-2

5.2 Water-Related Impacts ............................................................................................. 5-3

5.2.1 Hydrological Alterations ................................................................................ 5-4

5.2.2 Water-Use Impacts ....................................................................................... 5-5

5.2.2.1 Surface Water ................................................................................ 5-6

5.2.2.2 Groundwater-Use Impacts ........................................................... 5-11

5.2.3 Water-Quality Impacts ................................................................................ 5-15

5.2.3.1 Surface-Water Quality Impacts .................................................... 5-15

5.2.3.2 Groundwater-Quality Impacts ...................................................... 5-19

5.2.4 Water Monitoring ........................................................................................ 5-21

5.3 Ecological Impacts ................................................................................................. 5-22

5.3.1 Terrestrial and Wetland Impacts ................................................................. 5-22

5.3.1.1 Terrestrial Resources – Site and Vicinity ..................................... 5-23

5.3.1.2 Terrestrial Resources – Transmission Lines ................................ 5-25

5.3.1.3 Important Terrestrial Species and Habitats .................................. 5-27

5.3.1.4 Terrestrial Monitoring ................................................................... 5-31

5.3.1.5 Summary of Terrestrial Ecosystems Impacts .............................. 5-31

5.3.2 Aquatic Impacts .......................................................................................... 5-32

5.3.2.1 Aquatic Resources – Site and Vicinity ......................................... 5-32

5.3.2.2 Aquatic Resources – Transmission Lines .................................... 5-44

5.3.2.3 Important Aquatic Species and Habitats ...................................... 5-44

5.3.2.4 Aquatic Monitoring ....................................................................... 5-48

5.3.2.5 Summary of Impacts to Aquatic Resources ................................. 5-48

5.4 Socioeconomic Impacts ......................................................................................... 5-49

5.4.1 Physical Impacts ......................................................................................... 5-49

5.4.1.1 Workers and the Local Public ...................................................... 5-50

5.4.1.2 Buildings ...................................................................................... 5-51

5.4.1.3 Roads .......................................................................................... 5-51

5.4.1.4 Aesthetics .................................................................................... 5-51

5.4.1.5 Summary of Physical Impacts ...................................................... 5-51
NUREG-1937 xii February 2011 

5.4.2 Demography ............................................................................................... 5-51

5.4.3 Economic Impacts to the Community ......................................................... 5-52

5.4.3.1 Economy ...................................................................................... 5-53

5.4.3.2 Taxes ........................................................................................... 5-54

5.4.3.3 Summary of Economic Impacts ................................................... 5-56

5.4.4 Infrastructure and Community Services ..................................................... 5-57

5.4.4.1 Transportation .............................................................................. 5-57

5.4.4.2 Recreation ................................................................................... 5-58

5.4.4.3 Housing ........................................................................................ 5-58

5.4.4.4 Public Services ............................................................................ 5-59

5.4.4.5 Education ..................................................................................... 5-60

5.4.4.6 Summary of Infrastructure and Community Services .................. 5-60

5.4.5 Summary of Socioeconomic Impacts ......................................................... 5-61

5.5 Environmental Justice ............................................................................................ 5-61

5.5.1 Health Impacts ............................................................................................ 5-61

5.5.2 Physical and Environmental Impacts .......................................................... 5-62

5.5.2.1 Soil ............................................................................................... 5-63

5.5.2.2 Water ........................................................................................... 5-63

5.5.2.3 Air ................................................................................................ 5-63

5.5.2.4 Summary of Physical and Environmental Impacts ....................... 5-64

5.5.3 Socioeconomic Impacts .............................................................................. 5-64

5.5.4 Subsistence and Special Conditions .......................................................... 5-64

5.5.5 Summary of Environmental Justice Impacts .............................................. 5-65

5.6 Historic and Cultural Resource Impacts ................................................................. 5-65

5.7 Meteorological and Air Quality Impacts .................................................................. 5-66

5.7.1 Air Quality Impacts ..................................................................................... 5-66

5.7.2 Cooling System Impacts ............................................................................. 5-68

5.7.3 Summary .................................................................................................... 5-70

5.8 Nonradiological Health Impacts .............................................................................. 5-70

5.8.1 Etiological Agents ....................................................................................... 5-71

5.8.2 Noise .......................................................................................................... 5-73

5.8.3 Acute Effects of Electromagnetic Fields ..................................................... 5-74

5.8.4 Chronic Effects of Electromagnetic Fields .................................................. 5-75

5.8.5 Occupational Health ................................................................................... 5-76

5.8.6 Impacts of Transporting Operations Personnel to the Proposed Site ........ 5-77
February 2011 xiii NUREG-1937 

5.8.7 Summary of Nonradiological Health Impacts ............................................. 5-78

5.9 Radiological Impacts of Normal Operations ........................................................... 5-79

5.9.1 Exposure Pathways .................................................................................... 5-79

5.9.2 Radiation Doses to Members of the Public ................................................ 5-83

5.9.2.1 Liquid Effluent Pathway ............................................................... 5-83

5.9.2.2 Gaseous Effluent Pathway .......................................................... 5-84

5.9.3 Impacts to Members of the Public .............................................................. 5-85

5.9.3.1 Maximally Exposed Individual ...................................................... 5-85

5.9.3.2 Population Dose .......................................................................... 5-87

5.9.3.3 Summary of Radiological Impacts to Members of the Public ....... 5-88

5.9.4 Occupational Doses to Workers ................................................................. 5-88

5.9.5 Doses to Biota Other than Humans ............................................................ 5-89

5.9.5.1 Liquid Effluent Pathway ............................................................... 5-89

5.9.5.2 Gaseous Effluent Pathway .......................................................... 5-90

5.9.5.3 Impact of Estimated Non-Human Biota Doses ............................ 5-90

5.9.6 Radiological Monitoring .............................................................................. 5-91

5.10 Nonradioactive Waste Impacts ............................................................................... 5-93

5.10.1 Impacts to Land .......................................................................................... 5-93

5.10.2 Impacts to Water ........................................................................................ 5-94

5.10.3 Impacts to Air .............................................................................................. 5-95

5.10.4 Mixed Waste Impacts ................................................................................. 5-95

5.10.5 Summary of Waste Impacts ....................................................................... 5-95

5.11 Environmental Impacts of Postulated Accidents .................................................... 5-96

5.11.1 Design Basis Accidents .............................................................................. 5-98

5.11.2 Severe Accidents ...................................................................................... 5-100

5.11.2.1 Air Pathway ................................................................................ 5-101

5.11.2.2 Surface-Water Pathways ........................................................... 5-109

5.11.2.3 Groundwater Pathway ............................................................... 5-110

5.11.2.4 Summary ................................................................................... 5-110

5.11.3 Severe Accident Mitigation Alternatives ................................................... 5-111

5.11.4 Summary of Postulated Accident Impacts ................................................ 5-113

5.12 Measures and Controls to Limit Adverse Impacts During Operation ................... 5-113

5.13 Summary of Operational Impacts ......................................................................... 5-118

5.14 References ........................................................................................................... 5-120

6.0 Fuel Cycle, Transportation, and Decommissioning .......................................................... 6-1
NUREG-1937 xiv February 2011 

6.1 Fuel Cycle Impacts and Solid Waste Management .................................................. 6-1

6.1.1 Land Use ...................................................................................................... 6-8

6.1.2 Water Use ..................................................................................................... 6-8

6.1.3 Fossil Fuel Impacts ....................................................................................... 6-8

6.1.4 Chemical Effluents ........................................................................................ 6-9

6.1.5 Radiological Effluents ................................................................................. 6-10

6.1.6 Radiological Wastes ................................................................................... 6-12

6.1.7 Occupational Dose ..................................................................................... 6-15

6.1.8 Transportation ............................................................................................ 6-15

6.1.9 Conclusion .................................................................................................. 6-15

6.2 Transportation Impacts ........................................................................................... 6-16

6.2.1 Transportation of Unirradiated Fuel ............................................................ 6-18

6.2.1.1 Normal Conditions ....................................................................... 6-18

6.2.1.2 Radiological Impacts of Transportation Accidents ....................... 6-24

6.2.1.3 Nonradiological Impacts of Transportation Accidents .................. 6-24

6.2.2 Transportation of Spent Fuel ...................................................................... 6-25

6.2.2.1 Normal Conditions ....................................................................... 6-26

6.2.2.2 Radiological Impacts of Accidents ............................................... 6-32

6.2.2.3 Nonradiological Impact of Spent Fuel Shipments ........................ 6-35

6.2.3 Transportation of Radioactive Waste ......................................................... 6-36

6.2.4 Conclusions ................................................................................................ 6-38

6.3 Decommissioning Impacts ..................................................................................... 6-39

6.4 References ............................................................................................................. 6-40

7.0 Cumulative Impacts .......................................................................................................... 7-1

7.1 Land Use .................................................................................................................. 7-7

7.2 Water Use and Quality ............................................................................................. 7-8

7.2.1 Water Use Impacts ....................................................................................... 7-8

7.2.1.1 Surface Water-Use Impacts ......................................................... 7-10

7.2.1.2 Groundwater-Use Impacts ........................................................... 7-14

7.2.2 Water-Quality Impacts ................................................................................ 7-17

7.2.2.1 Surface-Water Quality Impacts .................................................... 7-17

7.2.2.2 Groundwater-Quality Impacts ...................................................... 7-20

7.3 Ecology ................................................................................................................... 7-22

7.3.1 Terrestrial and Wetland Ecosystem Impacts .............................................. 7-22

7.3.1.1 Wildlife and Plant Communities ................................................... 7-23
February 2011 xv NUREG-1937 

7.3.1.2 Important Species ........................................................................ 7-27

7.3.2 Aquatic Ecosystem Impacts ....................................................................... 7-30

7.4 Socioeconomics and Environmental Justice .......................................................... 7-36

7.4.1 Socioeconomics ......................................................................................... 7-36

7.4.2 Environmental Justice ................................................................................ 7-40

7.5 Historic and Cultural Resources ............................................................................. 7-42

7.6 Air Quality ............................................................................................................... 7-44

7.6.1 Criteria Pollutants ....................................................................................... 7-44

7.6.2 Greenhouse Gas Emissions ....................................................................... 7-45

7.6.3 Summary .................................................................................................... 7-46

7.7 Nonradiological Health ........................................................................................... 7-47

7.8 Radiological Impacts of Normal Operation ............................................................. 7-49

7.9 Postulated Accidents .............................................................................................. 7-51

7.10 Fuel Cycle, Transportation, and Decommissioning ................................................ 7-52

7.10.1 Fuel Cycle ................................................................................................... 7-52

7.10.2 Transportation ............................................................................................ 7-52

7.10.3 Decommissioning ....................................................................................... 7-55

7.11 Conclusions ............................................................................................................ 7-55

7.12 References ............................................................................................................. 7-58

8.0 Need for Power ................................................................................................................. 8-1

8.1 Description of Power System ................................................................................... 8-1

8.1.1 Description of STPNOC ................................................................................ 8-1

8.1.2 Description of ERCOT .................................................................................. 8-2

8.1.3 Description of the ERCOT Analytical Process .............................................. 8-5

8.1.3.1 Systematic Test ............................................................................. 8-5

8.1.3.2 Comprehensive Test ...................................................................... 8-5

8.1.3.3 Subject to Confirmation Test ......................................................... 8-6

8.1.3.4 Responsive to Forecasting Uncertainty Test ................................. 8-7

8.1.3.5 Summary of ERCOT Analytical Process ........................................ 8-7

8.2 Power Demand ......................................................................................................... 8-8

8.3 Power Supply ......................................................................................................... 8-19

8.4 Assessment of Need for Power .............................................................................. 8-27

8.4.1 Conclusion .................................................................................................. 8-32

8.5 References ............................................................................................................. 8-33
NUREG-1937 xvi February 2011 

9.0 Environmental Impacts of Alternatives ............................................................................. 9-1

9.1 No-Action Alternative ................................................................................................ 9-2

9.2 Energy Alternatives .................................................................................................. 9-3

9.2.1 Alternatives Not Requiring New Generating Capacity .................................. 9-3

9.2.2 Alternatives Requiring New Generating Capacity ........................................ 9-6

9.2.2.1 Coal-Fired Generation ................................................................... 9-7

9.2.2.2 Natural Gas-Fired Generation...................................................... 9-13

9.2.3 Other Alternatives ....................................................................................... 9-19

9.2.3.1 Oil-Fired Generation .................................................................... 9-20

9.2.3.2 Wind Power ................................................................................. 9-20

9.2.3.3 Solar Power ................................................................................. 9-23

9.2.3.4 Hydropower ................................................................................. 9-24

9.2.3.5 Geothermal Energy ...................................................................... 9-24

9.2.3.6 Wood Waste ................................................................................ 9-25

9.2.3.7 Municipal Solid Waste ................................................................. 9-26

9.2.3.8 Other Biomass-Derived Fuels ...................................................... 9-26

9.2.3.9 Fuel Cells ..................................................................................... 9-27

9.2.4 Combination of Alternatives ........................................................................ 9-28

9.2.5 Summary Comparison of Alternatives ........................................................ 9-30

9.3 Alternative Sites ..................................................................................................... 9-33

9.3.1 Alternative Sites Selection Process ............................................................ 9-33

9.3.1.1 Selection of Region of Interest ..................................................... 9-34

9.3.1.2 Selection of Candidate Areas. ..................................................... 9-34

9.3.1.3 Selection of Potential Sites .......................................................... 9-36

9.3.1.4 Selection of Primary Sites ............................................................ 9-37

9.3.1.5 Selection of Candidate Sites ........................................................ 9-39

9.3.1.6 Evaluation of STPNOC’s Site Selection Process ......................... 9-43

9.3.2 Red 2 .......................................................................................................... 9-45

9.3.2.1 Land Use ..................................................................................... 9-47

9.3.2.2 Water Use and Quality ................................................................. 9-50

9.3.2.3 Terrestrial and Wetland Resources ............................................. 9-59

9.3.2.4 Aquatic Resources ....................................................................... 9-70

9.3.2.5 Socioeconomics ........................................................................... 9-77

9.3.2.6 Environmental Justice .................................................................. 9-84

9.3.2.7 Historic and Cultural Resources .................................................. 9-87

9.3.2.8 Air Quality .................................................................................... 9-89

9.3.2.9 Nonradiological Health ................................................................. 9-91

9.3.2.10 Radiological Impacts of Normal Operations ................................. 9-93
February 2011 xvii NUREG-1937 

9.3.2.11 Postulated Accidents ................................................................... 9-94

9.3.3 Allens Creek ............................................................................................... 9-95

9.3.3.1 Land Use ..................................................................................... 9-98

9.3.3.2 Water Use and Quality ............................................................... 9-101

9.3.3.3 Terrestrial and Wetland Resources ........................................... 9-108

9.3.3.4 Aquatic Resources ..................................................................... 9-120

9.3.3.5 Socioeconomics ......................................................................... 9-129

9.3.3.6 Environmental Justice ................................................................ 9-135

9.3.3.7 Historic and Cultural Resources ................................................ 9-140

9.3.3.8 Air Quality .................................................................................. 9-143

9.3.3.9 Nonradiological Health ............................................................... 9-144

9.3.3.10 Radiological Impacts of Normal Operations ............................... 9-146

9.3.3.11 Postulated Accidents ................................................................. 9-147

9.3.4 Trinity 2 ..................................................................................................... 9-148

9.3.4.1 Land Use ................................................................................... 9-152

9.3.4.2 Water Use and Quality ............................................................... 9-155

9.3.4.3 Terrestrial and Wetland Resources ........................................... 9-163

9.3.4.4 Aquatic Resources ..................................................................... 9-175

9.3.4.5 Socioeconomics ......................................................................... 9-183

9.3.4.6 Environmental Justice ................................................................ 9-190

9.3.4.7 Historic and Cultural Resources ................................................ 9-194

9.3.4.8 Air Quality .................................................................................. 9-197

9.3.4.9 Nonradiological Health ............................................................... 9-198

9.3.4.10 Radiological Impacts of Normal Operations ............................... 9-200

9.3.4.11 Postulated Accidents ................................................................. 9-201

9.3.5 Comparison of the Impacts of the Proposed Action and Alternative 

Sites .......................................................................................................... 9-202

9.3.5.1 Comparison of Cumulative Impacts at the Proposed and 

Alternative Sites ......................................................................... 9-203

9.3.5.2 Environmentally Preferable Sites ............................................... 9-205

9.3.5.3 Obviously Superior Sites............................................................ 9-207

9.4 System Design Alternatives ................................................................................. 9-208

9.4.1 Heat Dissipation Systems ......................................................................... 9-208

9.4.1.1 Plant Cooling System – Once-Through Operation ..................... 9-208

9.4.1.2 Spray Canals ............................................................................. 9-209

9.4.1.3 Wet Mechanical Draft Cooling Towers....................................... 9-209

9.4.1.4 Wet Natural Draft Cooling Towers ............................................. 9-210

9.4.1.5 Dry Cooling Towers ................................................................... 9-210

9.4.1.6 Combination Wet/Dry Cooling Tower System ............................ 9-211
NUREG-1937 xviii February 2011 

9.4.2 Circulating Water Systems ....................................................................... 9-211

9.4.2.1 Intake Alternatives ..................................................................... 9-211

9.4.2.2 Discharge Alternatives ............................................................... 9-212

9.4.2.3 Water Supplies .......................................................................... 9-213

9.4.2.4 Water Treatment ........................................................................ 9-215

9.4.3 Conclusion ................................................................................................ 9-215

9.5 Corps’ Onsite Alternatives Evaluation .................................................................. 9-215

9.5.1 Onsite Alternative 1 .................................................................................. 9-215

9.5.2 Onsite Alternative 2 .................................................................................. 9-216

9.5.3 Onsite Alternative 3 (STPNOC’s Preferred Alternative) ........................... 9-216

9.6 References ........................................................................................................... 9-216

10.0 Conclusions and Recommendations .............................................................................. 10-1

10.1 Impacts of the Proposed Action ............................................................................. 10-3

10.2 Unavoidable Adverse Environmental Impacts ........................................................ 10-4

10.2.1 Unavoidable Adverse Impacts During Construction and 

Preconstruction ........................................................................................... 10-4

10.2.2 Unavoidable Adverse Impacts During Operation ....................................... 10-8

10.3 Relationship Between Short-Term Uses and Long-Term Productivity of 

the Human Environment ....................................................................................... 10-13

10.4 Irreversible and Irretrievable Commitments of Resources ................................... 10-14

10.4.1 Irreversible Commitments of Resources .................................................. 10-14

10.4.1.1 Land Use ................................................................................... 10-14

10.4.1.2 Water Use .................................................................................. 10-15

10.4.1.3 Aquatic and Terrestrial Biota...................................................... 10-15

10.4.1.4 Socioeconomic Resources ........................................................ 10-16

10.4.1.5 Air and Water ............................................................................. 10-16

10.4.2 Irretrievable Commitments of Resources ................................................. 10-16

10.5 Alternatives to the Proposed Action ..................................................................... 10-16

10.6 Benefit-Cost Balance ............................................................................................ 10-17

10.6.1 Benefits ..................................................................................................... 10-19

10.6.1.1 Societal Benefits ........................................................................ 10-20

10.6.1.2 Regional Benefits ....................................................................... 10-21

10.6.2 Costs ........................................................................................................ 10-22

10.6.2.1 Internal Costs ............................................................................. 10-25

10.6.2.2 External Costs ........................................................................... 10-27

10.6.3 Summary of Benefits and Costs ............................................................... 10-29
February 2011 xix NUREG-1937 

10.7 Staff Conclusions and Recommendations ........................................................... 10-29

10.8 References ........................................................................................................... 10-30

Appendix A – Contributors to the Environmental Impact Statement ......................................... A-1

Appendix B – Organizations Contacted .................................................................................... B-1

Appendix C – NRC and Corps Environmental Review Correspondence .................................. C-1

Appendix D – Scoping Comments and Responses .................................................................. D-1

Appendix E – Draft Environmental Impact Statement Comments and Responses .................. E-1

Appendix F – Key Consultation Correspondence ...................................................................... F-1

Appendix G – Supporting Documentation for Socioeconomic and Radiological Dose 

Assessment ..................................................................................................................... G-1

Appendix H – Authorizations, Permits, and Certifications ......................................................... H-1

Appendix I – Carbon Dioxide Footprint Estimates for a 1000 MW(e) Light Water Reactor 

(LWR) ................................................................................................................................ I-1

Appendix J – U.S. Army Corps of Engineers Cumulative Effect Resource Analysis Table ....... J-1

Appendix K – U.S. Army Corps of Engineers Public Notice Comments ................................... K-1
NUREG-1937 xx February 2011 

Figures 

2-1 STP Site and Proposed Plant Footprint ........................................................................... 2-2

2-2 STP Site and Vicinity ....................................................................................................... 2-3

2-3 Land-Use Classifications at STP Site .............................................................................. 2-4

2-4 Landscape Features and Habitat Types of the STP Site ................................................. 2-5

2-5 Land-Use Classifications in the Vicinity of the STP Site .................................................. 2-6

2-6 Land-Use Classifications in STP 50-mi Region ............................................................. 2-10

2-7 Location of the STP Site and the Adjacent Watersheds ................................................ 2-13

2-8 The Colorado River Basin .............................................................................................. 2-14

2-9 Location of the STP Site with Respect to Nearby Cities, the Matagorda Bay, and 

the Gulf of Mexico .......................................................................................................... 2-15

2-10 Daily Mean Colorado River Discharge near Bay City, Texas ........................................ 2-16

2-11 The Six LCRA Dams and the Corresponding Highland Lakes They Impound .............. 2-18

2-12 Current and Previous Locations of the Main Drainage Channel .................................... 2-20

2-13 Kelly Lake and Local Drainages Flowing Into and Out of the Lake ............................... 2-21

2-14 Correlation of USGS and Texas Nomenclature ............................................................. 2-24

2-15 Aquifers of Texas ........................................................................................................... 2-25

2-16 Generalized Hydrostratigraphic Section Underlying the STP Site ................................. 2-30

2-17 Hydrological Monitoring Locations for Existing STP Units 1 and 2 ................................ 2-45

2-18 Stormwater Monitoring Locations for Existing STP Units 1 and 2 ................................. 2-47

2-19 Vegetation Cover and Land-Use Cover Types at the STP Site ..................................... 2-50

2-20 Locations of Wildlife Refuges and Critical Habitat Within 50 mi of the STP Site ........... 2-59

2-21 Location of STP with Respect to Important Aquatic Resources and the 1975-1976 

Aquatic Ecology Sampling Locations ............................................................................. 2-71

2-22 Aquatic Ecology Sampling Locations for 2007-2008, from NMM 5 to 9 ........................ 2-80

2-23 Aquatic Ecology Sampling Locations for 2007-2008, from GIWW to NMM 4 ................ 2-81

2-24 Map of Central Texas Gulf Coast, Showing Counties Potentially Affected by the 

Proposed Units 3 and 4 ............................................................................................... 2-112

2-25 Road, Highway, and Rail Transportation System ........................................................ 2-128

2-26 Main Routes to STP Site ............................................................................................. 2-129

2-27 Aggregate Minority Populations in Block Groups Meeting Environmental Justice 

Selection Criteria ......................................................................................................... 2-149

2-28 Black or African American Populations in Block Groups Meeting Environmental 

Justice Selection Criteria ............................................................................................. 2-150

2-29 Asian or Pacific Islander Populations in Block Groups Meeting Environmental 

Justice Selection Criteria ............................................................................................. 2-151

2-30 Hispanic Populations in Block Groups Meeting Environmental Justice Selection 

Criteria ......................................................................................................................... 2-152
February 2011 xxi NUREG-1937 

2-31 Aggregate Low-Income Populations in Block Groups Meeting Environmental 

Justice Selection Criteria ............................................................................................. 2-154

3-1 Representative Ground-Level Photograph of STP Units 1 and 2 .................................... 3-2

3-2 Simplified Flow Diagram of Reactor Power Conversion System ..................................... 3-4

3-3 STP Site Layout Map ....................................................................................................... 3-5

4-1 Total Workforce, STP Units 3 and 4 .............................................................................. 4-42

5-1 Exposure Pathways to Man ........................................................................................... 5-81

5-2 Exposure Pathways to Biota Other Than Man ............................................................... 5-82

6-1 The Uranium Fuel Cycle: No-Recycle Option .................................................................. 6-6

6-2 Illustration of Truck Stop Model ..................................................................................... 6-29

7-1 Geographic Area of Interest Evaluated to Assess Cumulative Impacts to 

Terrestrial Ecological Resources ................................................................................... 7-24

8-1 Map of the ERCOT ISO Service Area ............................................................................. 8-3

8-2 Peak Demand and Average Demand in the ERCOT Region 2010-2019 ....................... 8-9

8-3 ERCOT 2009 Load Duration Curve ............................................................................... 8-10

8-4 ERCOT 2006, 2007, 2008, 2009, and 2010 Peak Load Forecasts ............................... 8-11

8-5 ERCOT 2009 and 2010 Energy Demand Forecasts ..................................................... 8-12

8-6 Population in the ERCOT Region .................................................................................. 8-13

8-7 Total Non-Farm Employment in the ERCOT Region ..................................................... 8-14

8-8 Per Capita Income in the ERCOT Region ..................................................................... 8-14

8-9 ERCOT Net Load Duration Curve in 2018 with 18,456 MW of Wind Generation 

Capacity ......................................................................................................................... 8-21

8-10 Alternative ERCOT Generation Capacity Reduction Scenarios vs. Projected 

Demand ......................................................................................................................... 8-24

9-1 Candidate Areas ............................................................................................................ 9-35 

9-2 Potential Sites ................................................................................................................ 9-38

9-3 Screening Criteria Evaluation Results ........................................................................... 9-39

9-4 Primary Sites ................................................................................................................. 9-40

9-5 Red 2 Alternative Site and 10-mi Radius ....................................................................... 9-48

9-6 Geographic Area of Analysis of Cumulative Impacts to Terrestrial Resources for 

the Red 2 Site in Grayson and Fannin Counties ........................................................... 9-60

9-7 Block Groups with Minority Populations Meeting Environmental Justice Selection 

Critera within 50 mi of the Red 2 Alternative Site .......................................................... 9-85

9-8 Block Groups with Low-Income Populations Meeting Environmental Justice 

Selection Criteria Within 50 mi of the Red 2 Alternative Site ......................................... 9-86

9-9 Allens Creek Alternative Site and 10-mi Radius ............................................................ 9-99

9-10 Geographic Area for the Analysis of Cumulative Impacts to Terrestrial Resources 

Within the Western Gulf Coast Plains Ecoregion in the Lower Brazos and San 

Bernard watersheds within Austin, Colorado, Wharton, Waller, and Fort Bend 

Counties ...................................................................................................................... 9-109
NUREG-1937 xxii February 2011 

9-11 Block Groups with Minority Populations Meeting Environmental Justice Selection 

Criteria Within 50 mi of the Allens Creek Alternative Site ............................................ 9-137

9-12 Block Groups with Low-Income Populations Meeting Enviornmental Justice 

Selection Criteria Within 50 mi of the Allens Creek Alternative Site ............................ 9-138

9-13 Trinity 2 Alternative Site and 10-mi Radius .................................................................. 9-154

9-14 Geographic Area of Analysis of Cumulative Impacts to Terrestrial Resources for 

the Trinity 2 Site in Freestone County ......................................................................... 9-165

9-15 Block Groups With Minority Populations Meeting Environmental Justice Selection 

Criteria Within 50 mi of the Trinity 2 Alternative Site ................................................... 9-192

9-16 Block Groups With Low-Income Popualtions Meeting Environmental Justice 

Selection Criteria Within 50 mi of the Trinity 2 Alternative Site .................................... 9-193
February 2011 xxiii NUREG-1937 

Tables 

2-1 Land Use at the STP Site ................................................................................................ 2-7

2-2 Representative Hydrogeologic Properties of Confining Layers in the STP 

Hydrogeologic Strata ..................................................................................................... 2-31

2-3 Representative Hydrogeologic Properties of Aquifers in the STP Hydrogeologic 

Strata ............................................................................................................................. 2-32

2-4 Groundwater Resource Estimates for Matagorda County ............................................. 2-39

2-5 Maximum Tritium Concentration in Water Bodies Near the STP Site ........................... 2-46

2-6 Approximate Acreages of Habitats and Land Use Found on the STP Site ................... 2-51

2-7 Amphibians Found in Matagorda County, Texas ........................................................... 2-53

2-8 Birds Observed On or Around the STP Project Area for Units 3 and 4 ......................... 2-55

2-9 Federally Listed Terrestrial Species Identified by FWS as Occurring in the Vicinity 

of the STP Site and the STP-to-Hillje Transmission Corridor ........................................ 2-57

2-10 State-Listed Species Occurring or Potentially Occurring in the Region of the STP 

Site and the STP-to-Hillje Transmission Corridor .......................................................... 2-61

2-11 Fish and Shellfish Collected in the MCR by Gear Type, 2007-2008 ............................. 2-73

2-12 Aquatic Species Collected during Impingement Sampling in the MCR’s CWIS for 

Units 1 and 2, 2007-2008 .............................................................................................. 2-74

2-13 Aquatic Species Collected During Entrainment Sampling in the MCR’s CWIS for 

Units 1 and 2, 2007-2008 .............................................................................................. 2-75

2-14 Fish and Shellfish Collected in the Colorado River by Gear Type, 2007-2008 .............. 2-83

2-15 Important Aquatic Species that May Occur in the Vicinity of STP Site .......................... 2-89

2-16 Distribution of STP Employees, January 2007 ............................................................ 2-110

2-17 Counties within 50 mi of the STP Site ......................................................................... 2-111

2-18 Historical and Projected Populations for Counties in the STP Region ........................ 2-114

2-19 Municipalities in the 50-mi Region Surrounding the STP Site ..................................... 2-115

2-20 Hotels Nights Available and Sold in Four-County Socioeconomic Impact Area 

Surrounding the STP Site, 2006 .................................................................................. 2-116

2-21 Minority and Low-Income Populations ......................................................................... 2-118

2-22 Employment by Industry, 2006 .................................................................................... 2-119

2-23 Major Employers in Matagorda, Brazoria, Calhoun, and Jackson Counties ................ 2-120

2-24 Employment and Unemployment Statistics for Matagorda, Brazoria, Calhoun, and 

Jackson Counties ........................................................................................................ 2-122

2-25 Matagorda County Property Tax Information, 2000-2005 ........................................... 2-124

2-26 Property Tax Statistics for Matagorda County and Special Districts 2001-2006 ......... 2-124

2-27 Palacios Independent School District Property Tax Revenues and Disposition 

2000-2005 ................................................................................................................... 2-126

2-28 Roadway Use Statistics for Most Likely Routes to the STP Site ................................. 2-130

2-29 Wildlife Management Areas and Parks Within 50 mi of the STP Site .......................... 2-131
NUREG-1937 xxiv February 2011 

2-30 Regional Housing Information by County for the Year 2000 ....................................... 2-133

2-31 Water Supply, Capacity, and Average Daily Consumption by Major Water Supply 

Systems in Brazoria, Calhoun, Jackson, and Matagorda Counties ............................. 2-136

2-32 Designed Capacity and Maximum Water Treated in Wastewater Treatment 

Systems in Brazoria, Calhoun, Jackson, and Matagorda Counties ............................. 2-137

2-33 Law Enforcement Personnel 2005 ............................................................................... 2-139

2-34 Fire Protection Personnel ............................................................................................ 2-140

2-35 Hospital Data for Brazoria, Calhoun, Jackson and Matagorda Counties ..................... 2-142

2-36 United Way Agencies of Matagorda County ................................................................ 2-144

2-37 Public School Statistics in the Four-County Socioeconomic Impact Area, 

2005-2006 ................................................................................................................... 2-145

2-38 Private School Statistics in the Four-County Socioeconomic Impact Area, 2005-

2006 ............................................................................................................................. 2-146

2-39 Atmospheric Dispersion Factors for Proposed Units 3 and 4 Design Basis 

Accident Calculations .................................................................................................. 2-166

2-40 Maximum Annual Average Atmospheric Dispersion and Deposition Factors for 

Evaluation of Normal Effluents for Receptors of Interest ............................................. 2-167

2-41 Construction Noise Sources and Attenuation with Distance ........................................ 2-171

3-1 Descriptions and Examples of Activities Associated with Building Units 3 and 4 .......... 3-14

3-2 Summary of Resource Commitments Associated with Building Proposed Units 3 

and 4 .............................................................................................................................. 3-18

3-3 Representative Water Treatment Chemicals Used for STP Units 1 and 2 .................... 3-24

3-4 Summary of Resource Commitments Associated with Operation of Proposed STP 

Units 3 and 4.................................................................................................................. 3-25

4-1 Drawdown in Feet at the STP Property Line (100 ft) and a Point 2500 ft from a 

Production Well .............................................................................................................. 4-10

4-2 Estimated Acreage Affected by Proposed Activities by Habitat Type and Land Use .... 4-15

4-3 Calculation of Traffic Impacts on FM 521 from Building Activities at Proposed 

Units 3 and 4, Months 26-35 .......................................................................................... 4-47

4-4 Estimated Impacts of Transporting Workers and Materials to and from the STP 

Site for a Single ABWR.................................................................................................. 4-71

4-5 Direct Radiation Doses to Unit 4 Construction Workers ................................................ 4-73

4-6 Summary of Measures and Controls Proposed by STPNOC to Limit Adverse 

Impacts During Construction of Proposed Units 3 and 4 ............................................... 4-79

4-7 Summary of Construction and Preconstruction Impacts for Proposed Units 3 and 4 .... 4-85

5-1 Summary Statistics of Simulated Colorado River Streamflow Below the RMPF ........... 5-10

5-2 Drawdown at the STP Property Line (100 ft) and a Point 2500 ft from a Production 

Well ................................................................................................................................ 5-13

5-3 Summary Statistics of Simulated Water Temperature and Total Dissolved Solids 

of MCR Discharge ......................................................................................................... 5-16

5-4 Potential Increase in Resident Population Resulting from Operating Units 3 and 4 ...... 5-52
February 2011 xxv NUREG-1937 

5-5 Estimated Operations Impacts to Property Taxes for Matagorda County and 

Special Districts ............................................................................................................. 5-56

5-6 Anticipated Atmospheric Emissions Associated With Operation of Proposed Units 

3 and 4 ........................................................................................................................... 5-67

5-7 MCR Fog Impact Analysis ............................................................................................. 5-69

5-8 Nonradiological Estimated Impacts of Transporting Operations Workers to and 

from the STP Site .......................................................................................................... 5-78

5-9 Annual Doses to the MEI for Liquid Effluent Releases from a New Unit ....................... 5-84

5-10 Annual Doses to MEI for Gaseous Effluent Releases from a New Unit ........................ 5-85

5-11 Comparison of Annual MEI Dose Rates for a Single Unit with 10 CFR 50, 

Appendix I Design Objectives ........................................................................................ 5-86

5-12 Comparison of MEI Annual Doses with 40 CFR Part 190 Standards – (mrem/yr) ........ 5-87

5-13 Biota Doses for Proposed Units 3 and 4 ........................................................................ 5-90

5-14 Comparison of Biota Doses from the Proposed Units 3 and 4 at the STP Site to 

Relevant Guidelines for Biota Protection ....................................................................... 5-91

5-15 Atmospheric Dispersion Factors for STP Site DBA Calculations .................................. 5-99

5-16 Design Basis Accident Doses for an ABWR .................................................................. 5-99

5-17 Mean Environmental Risks from ABWR Reactor Severe Accidents at the STP Site .. 5-103

5-18 Comparison of Environmental Risks for an ABWR Reactor at the STP Site with 

Risks for Current-Generation Reactors at Five Sites Evaluated in NUREG-1150 ....... 5-104

5-19 Comparison of Environmental Risks from Severe Accidents Initiated by Internal 

Events for an ABWR Reactor at the STP Site with Risks Initiated by Internal 

Events for Current Plants Undergoing Operating License Renewal Review and 

Environmental Risks of the ABWR Reactor at Other Sites .......................................... 5-105

5-20 Summary of Proposed Measures and Controls to Limit Adverse Impacts During 

Operation ..................................................................................................................... 5-114

5-21 Summary of Operational Impacts at the Proposed Units 3 and 4 Site ........................ 5-118

6-1 Table S–3 from 10 CFR 51.51(b), Table of Uranium Fuel Cycle Environmental 

Data ................................................................................................................................. 6-2

6-2 Comparison of Annual Average Dose Received by an Individual from All Sources ...... 6-13

6-3 Numbers of Truck Shipments of Unirradiated Fuel for the Reference LWR and the 

ABWR ............................................................................................................................ 6-19

6-4 RADTRAN 5.6 Input Parameters for Unirradiated Fuel Shipments ............................... 6-20

6-5 Radiological Impacts Under Normal Conditions of Transporting Unirradiated Fuel 

to the STP Site or Alternative Sites ............................................................................... 6-21

6-6 Nonradiological Impacts of Transporting Unirradiated Fuel to the STP Site and 

Alternative Sites, Normalized to Reference LWR .......................................................... 6-25

6-7 Transportation Route Information for Shipments from the STP Site and Alternative 

Sites to the Proposed Geologic Repository at Yucca Mountain, Nevada ...................... 6-27

6-8 RADTRAN 5.6 Normal (Incident-free) Exposure Parameters ........................................ 6-28
NUREG-1937 xxvi February 2011 

6-9 Normal (Incident-Free) Radiation Doses to Transport Workers and the Public from 

Shipping Spent Fuel from the STP Site and Alternative Sites to the Proposed 

Geologic HLW Repository at Yucca Mountain ............................................................... 6-30

6-10 Radionuclide Inventories Used in Transportation Accident Risk Calculations for an 

ABWR ............................................................................................................................ 6-33

6-11 Annual Spent Fuel Transportation Accident Impacts for an ABWR at the STP Site 

and Alternative Sites, Normalized to Reference 1100-MW(e) LWR Net Electrical 

Generation ..................................................................................................................... 6-35

6-12 Nonradiological Impacts of Transporting Spent Fuel from the STP Site and 

Alternative Sites to the Proposed Geologic HLW Repository at Yucca Mountain, 

Nevada, Normalized to Reference LWR ........................................................................ 6-36

6-13 Summary of Radioactive Waste Shipments from the STP Site and Alternative 

Sites ............................................................................................................................... 6-37

6-14 Nonradiological Impacts of Radioactive Waste Shipments from the STP Site .............. 6-38

7-1 Past, Present, and Reasonably Foreseeable Future Projects and Other Actions 

Considered in the STP Cumulative Analysis. .................................................................. 7-3

7-2 Comparison of Annual Carbon Dioxide Emission Rates ............................................... 7-46

7-3 Cumulative Impacts on Environmental Resources, Including the Impacts of 

Proposed Units 3 and 4 ................................................................................................. 7-56

8-1 ERCOT Peak Demand and Calculated Reserve Margin, 2010-2015 ............................ 8-17

8-2 Calculated ERCOT Reserve Margin, 2009-2025 ........................................................... 8-18

8-3 ERCOT Region Forecasted Summer Resources, 2010-2025 ....................................... 8-22

8-4 STPNOC Forecasted Summer Capacity, Baseload Generation Units Only .................. 8-25

8-5 Review Team Sensitivity Test, ERCOT Region Forecasted Summer Resources, 

2010-2025 ..................................................................................................................... 8-28

8-6 ERCOT/Review Team Forecasted Summer Capacity, Baseload Generation Units 

Only ............................................................................................................................... 8-29

8-7 ERCOT/Review Team Forecasted Unmet Need for Baseload Generation 

Compared with STPNOC Estimated Need for Baseload Power .................................... 8-32

9-1 Summary of Environmental Impacts of Coal-Fired Power Generation .......................... 9-14

9-2 Summary of Environmental Impacts of Natural Gas-Fired Power Generation .............. 9-19

9-3 Summary of Environmental Impacts of a Combination of Power Sources .................... 9-29

9-4 Summary of Environmental Impacts of Construction and Operation of New 

Nuclear, Coal-Fired, and Natural Gas-Fired Generating Units, and a Combination 

of Alternatives ................................................................................................................ 9-31

9-5 Comparison of Direct Carbon Dioxide Emissions for Energy Alternatives .................... 9-32

9-6 Criteria for Selection of Candidate Sites ........................................................................ 9-41

9-7 Composite Ratings for the Primary Sites ....................................................................... 9-42

9-8 Past, Present, and Reasonably Foreseeable Future Projects and Other Actions 

Considered in the Cumulative Analysis of the Red 2 Alternative Site ........................... 9-46
February 2011 xxvii NUREG-1937 

9-9 Estimated Land Cover Classes for Approximately 2000 ac of the 2500 ac Red 2 

Site. ............................................................................................................................... 9-61

9-10 Federally and State-listed Threatened and Endangered Species in Fannin County, 

Texas ............................................................................................................................. 9-63

9-11 State-Listed Aquatic Species that are Endangered, Threatened, and Species of 

Concern for Fannin County............................................................................................ 9-73

9-12 Past, Present, and Reasonably Foreseeable Future Projects and Other Actions 

Considered in the Allens Creek Alternative Site Cumulative Analysis ........................... 9-96

9-13 Estimated Acreages by Land Cover Classes for Approximately 300 ac of the 

800-ac Allens Creek Site. ............................................................................................ 9-110

9-14 List of Federal and State Threatened and Endangered Species in Austin, Fort 

Bend, Colorado, and Wharton Counties, Texas .......................................................... 9-112

9-15 Federally and State-Listed Aquatic Species that are Endangered, Threatened, 

and Species of Concern for Austin County .................................................................. 9-125

9-16 Past, Present, and Reasonably Foreseeable Future Projects and Other Actions 

Considered in the Cumulative Analysis of the Trinity 2 Alternative Site. ..................... 9-149

9-17 Estimated Land Cover Classes for Approximately 2000 ac of the 2500-ac Trinity 2 

Site. ............................................................................................................................. 9-166

9-18 Federally and State-listed Threatened and Endangered Species in Freestone 

County, Texas.............................................................................................................. 9-168

9-19 Federally and State-Listed Aquatic Species that are Endangered, Threatened, 

and Species of Concern for Freestone County ............................................................ 9-179

9-20 Comparison of Cumulative Impacts at the Proposed and Alternative Sites ................ 9-204

10-1 Unavoidable Adverse Environmental Impacts from Construction and 

Preconstruction Activities ............................................................................................... 10-4

10-2 Unavoidable Adverse Environmental Impacts from Operation ...................................... 10-8

10-3 Summary of Benefits of the Proposed Action .............................................................. 10-19

10-4 Summary of Costs of Preconstruction, Construction, and Operation .......................... 10-22

February 2011 xxix NUREG-1937 

Executive Summary 

By letter dated September 20, 2007, the U.S. Nuclear Regulatory Commission (NRC or the 

Commission) received an application from STP Nuclear Operating Company (STPNOC) for 

combined construction permits and operating licenses (combined licenses or COLs) for South 

Texas Project Electric Generating Station (STP) Units 3 and 4, located in Matagorda County, 

Texas. The review team’s evaluation is based on the October 2010 revision to the application, 

responses to requests for additional information, and supplemental letters. 

The proposed actions related to the STP Units 3 and 4 application are (1) NRC issuance of 

COLs for construction and operation of two new nuclear units at the STP site, and (2) U.S. Army 

Corps of Engineers (Corps) issuance of a permit pursuant to Section 404 of the Federal Water 

Pollution Control Act (Clean Water Act) and Section 10 of the Rivers and Harbors Act to perform 

certain construction activities on the site. The Corps is participating with the NRC in preparing 

this environmental impact statement (EIS) as a cooperating agency and participates 

collaboratively on the review team. The reactor specified in the application is the certified U.S. 

Advanced Boiling Water Reactor design, as modified by a proposed amendment to the ABWR 

design certification that is being sought by STPNOC to address the requirements of 10 CFR 

50.150 on the ability of the design to withstand the impact of a large commercial aircraft 

(U.S. ABWR, hereafter referred to as ABWR in this EIS). 

Section 102 of the National Environmental Policy Act of 1969, as amended (NEPA) 

(42 USC 4321 et seq.) directs that an EIS be prepared for major Federal actions that 

significantly affect the quality of the human environment. The NRC has implemented 

Section 102 of NEPA in Title 10 of the Code of Federal Regulations (CFR) Part 51. Further, in 

10 CFR 51.20, the NRC has determined that the issuance of a COL under 10 CFR Part 52 is an 

action that requires an EIS. 

The purpose of STPNOC’s requested NRC action—issuance of the COLs—is to obtain licenses 

to construct and operate two new nuclear units. These licenses are necessary but not sufficient 

for construction and operation of the units. A COL applicant must obtain and maintain the 

necessary permits from other Federal, State, Tribal, and local agencies and permitting 

authorities. Therefore, the purpose of the NRC’s environmental review of the STPNOC 

application is to determine if two new nuclear units of the proposed design can be constructed 

and operated at the STP site without unacceptable adverse impacts on the human environment. 

The purpose of STPNOC’s requested Corps action is to obtain a permit to perform regulated 

activities that would impact waters of the United States. 

Upon acceptance of the STPNOC application, the NRC began the environmental review 

process described in 10 CFR Part 51 by publishing in the Federal Register a Notice of Intent 
NUREG-1937 xxx February 2011 

(72 FR 72774) to prepare an EIS and conduct scoping. On February 5, 2008, the NRC held two 

scoping meetings in Bay City, Texas, to obtain public input on the scope of the environmental 

review. The staff reviewed the comments received during the scoping process and contacted 

Federal, State, Tribal, regional, and local agencies to solicit comments. 

To gather information and to become familiar with the sites and their environs, the NRC and its 

contractor Pacific Northwest National Laboratory (PNNL) visited the STP site in February 2008 

and the Allens Creeks alternative site in March 2008. In August 2009, the NRC and PNNL 

visited the Red 2 and Trinity 2 alternative sites. During the site visits, the NRC staff and its 

contractors met with STPNOC staff, public officials, and the public. 

Included in this EIS are (1) the results of the review team’s analyses, which consider and weigh 

the environmental effects of the proposed actions; (2) potential mitigation measures for reducing 

or avoiding adverse effects; (3) the environmental impacts of alternatives to the proposed 

action; and (4) the NRC staff’s recommendation regarding the proposed action. 

To guide its assessment of the environmental impacts of a proposed action or alternative 

actions, the NRC has established a standard of significance for impacts based on Council on 

Environmental Quality guidance (40 CFR 1508.27). Table B-1 of 10 CFR Part 51, Subpart A, 

Appendix B, provides the following definitions of the three significance levels – SMALL, 

MODERATE, and LARGE: 

SMALL – Environmental effects are not detectable or are so minor that they will 

neither destabilize nor noticeably alter any important attribute of the resource. 

MODERATE – Environmental effects are sufficient to alter noticeably, but not to 

destabilize, important attributes of the resource. 

LARGE – Environmental effects are clearly noticeable and are sufficient to 

destabilize important attributes of the resource. 

In preparing this EIS, the review team reviewed the application, including the Environmental 

Report (ER) submitted by STPNOC; consulted with Federal, State, Tribal, and local agencies; 

and followed the guidance set forth in NUREG-1555, Environmental Standard Review Plan and 

Staff Memorandum on Addressing Construction and Preconstruction, Greenhouse Gas Issues, 

General Conformity Determinations, Environmental Justice, Need for Power, Cumulative Impact 

Analysis, and Cultural/Historical Resources Analysis Issues in Environmental Impact 

Statements. In addition, the NRC staff considered the public comments related to the 

environmental review received during the scoping process. Comments within the scope of the 

environmental review are included in Appendix D of this EIS. 
February 2011 xxxi NUREG-1937 

A 75-day comment period began on March 26, 2010, when the U.S. Environmental Protection 

Agency (EPA) published a Notice of Availability of the draft EIS to allow members of the public 

and agencies to comment on the results of the environmental review. During this period, the 

NRC and Corps staff conducted two public meetings in Bay City, Texas, to describe the results 

of the environmental review, respond to questions, and accept public comment. All comments 

received on the draft EIS are included in Appendix E. 

The NRC staff’s recommendation to the Commission related to the environmental aspects of the 

proposed action is that the COLs be issued as requested. This recommendation is based on 

(1) the application, including the ER submitted by STPNOC; (2) consultation with other Federal, 

State, Tribal, and local agencies; (3) the staff’s independent review; (4) the staff’s consideration 

of public comments; and (5) the assessments summarized in this EIS, including the potential 

mitigation measures identified in the ER and this EIS. The Corps will issue its Record of 

Decision based, in part, on this EIS. 

The NRC staff’s evaluation of the site safety and emergency preparedness aspects of the 

proposed action will be addressed in the NRC’s Safety Evaluation Report, which is still being 

developed. 

February 2011 xxxiii NUREG-1937 

Abbreviations/Acronyms 

AADT Average Annual Daily Traffic 

ABWR U.S. Advanced Boiling Water Reactor 

ac acre(s) 

ac-ft/yr acre-feet per year 

ACHP Advisory Council on Historic Preservation 

ADAMS Agencywide Documents Access and Management System 

AEC U.S. Atomic Energy Commission 

AEP American Electric Power 

AEP Archaeology and Ethnography Program 

AIA Aircraft Impact Assessment 

APE area of potential effect 

ALARA as low as is reasonably achievable 

ARRA American Recovery and Reinvestment Act of 2009 

ASLB Atomic Safety and Licensing Board 

BACT best available control technology 

BEA Bureau of Economic Analysis 

BEIR Biological Effects of Ionizing Radiation 

BGCD Bluebonnet Groundwater Conservation District 

BGS below ground surface 

BMP best management practice 

Btu British thermal unit(s) 

Bq Becquerel(s) 

BRA Brazos River Authority 

BWR boiling water reactor 

°C degree(s) Celsius 

CAES compressed air energy storage 

CBC Christmas Bird Count 

CCD Census County Division 

CDC Centers for Disease Control and Prevention 

CDF core damage frequency 

CDR Capacity, Demand, and Reserves Report 

CEQ Council on Environmental Quality 

CFR Code of Federal Regulations 

cfs cubic feet per second 

Ci curie(s) 

cm centimeter(s) 
NUREG-1937 xxxiv February 2011 

CMP Coastal Management Program 

CMZ Coastal Management Zone 

CNP CenterPoint Energy 

CO carbon monoxide 

CO2 carbon dioxide 

COL combined license 

CORMIX Cornell Mixing Zone Expert System 

Corps U.S. Army Corps of Engineers 

CPGCD Coastal Plains Groundwater Conservation District 

CPS Energy City Public Service Board of San Antonio, Texas 

CPUE catch per unit effort 

CR County Road (CR 360, CR 392) 

CREZ Competitive Renewable Energy Zones 

CWA Clean Water Act 

CWIS circulating water intake structure 

CWS circulating water system 

CZMA Coastal Zone Management Act 

DBA Design Basis Accident 

dBA decibel(s) (acoustic) 

DC design certification 

DCD Design Control Document 

DOE U.S. Department of Energy 

DOT U.S. Department of Transportation 

DSM demand side management 

D/Q deposition values 

DWS drinking water standards 

EA Environmental Assessment 

EAB Exclusion Area Boundary 

ECP Essential Cooling Pond 

EIA Energy Information Administration 

EIS environmental impact statement 

EFH essential fish habitat 

ELF extremely low frequency 

ELCC effective load carrying capability 

EMF electromagnetic field 

EOF Emergency Operations Facility 

EPA U.S. Environmental Protection Agency 

ER Environmental Report 

ERCOT Electric Reliability Council of Texas 
February 2011 xxxv NUREG-1937 

ESA Endangered Species Act of 1973, as amended 

ESRP Environmental Standard Review Plan 

°F degree(s) Fahrenheit 

FAA Federal Aviation Administration 

FDA final design approval 

FERC Federal Energy Regulatory Commission 

FES Final Environmental Statement 

FM Farm-to-Market 

FMP Fishery Management Plan 

fps feet per second 

FR Federal Register 

FSAR Final Safety Analysis Report 

FSC Federal Species of Concern 

FSER Final Safety Evaluation Report 

ft foot or feet 

ft2 square feet 

ft3

 cubic feet 

FWS U.S. Fish and Wildlife Service 

GBq gigabecquerel 

GCC global climate change 

GCRP U.S. Global Change Research Program 

GE General Electric 

GEIS generic environmental impact statement 

GHG greenhouse gases 

GIT Georgia Institute of Technology 

GIWW Gulf Intracoastal Waterway 

gpd gallon(s) per day 

gpm gallon(s) per minute 

GWMS gaseous waste-management system 

ha hectare(s) 

HAPC habitat areas of particular concern 

hr hour(s) 

Hg mercury 

HLW high-level waste 

Hz hertz 

IAEA International Atomic Energy Agency 

ICRP International Commission on Radiological Protection 
NUREG-1937 xxxvi February 2011 

IGCC integrated gasification combined cycle 

in. inch 

INEEL Idaho National Engineering and Environmental Laboratory 

IOU investor owned utility 

ISD Independent School District 

ISO independent system operator 

I&S interest and sinking fund 

 

km kilometer(s) 

km2

 square kilometer(s) 

kWh kilowatt-hour(s) 

kV kilovolt(s) 

L liter(s) 

lb pound(s) 

LCRA Lower Colorado River Authority 

LCRWPG Lower Colorado Regional Water Planning Group 

LEDPA least environmentally damaging practicable alternative 

LERF large early release frequency 

LLW low-level waste 

LNG liquefied natural gas 

LOS level of service 

LPZ Low Population Zone 

LRF large release frequency 

LST local standard time 

LSWP LCRA-SAWS Water Project 

LTDEF long-term demand energy forecast 

LTSF Long-Term Storage Facility 

LWA Limited Work Authorization 

LWMS liquid waste management system 

LWR light water reactor 

m meter(s) 

m3

 cubic meter(s) 

MACCS2 MELCOR Accident Consequence Code System Version 2 

MBq megabecquerel(s) 

MCEDC Matagorda County Economic Development Corporation 

MCEMO Matagorda County Emergency Management Office 

MCPE market clearing prices of energy 

MCR Main Cooling Reservoir 

MDC Main Drainage Channel 
February 2011 xxxvii NUREG-1937 

MEI maximally exposed individual 

METGCD Mid-East Texas Groundwater Conservation District 

mg milligram(s) 

MGD million gallons per day 

mg/L milligram(s) per liter 

mi mile(s) 

mi2

 square mile(s) 

MIT Massachusetts Institute of Technology 

mL milliliter(s) 

MMS Minerals Management Service 

mo month 

MOU Memorandum of Understanding 

M&O maintenance and operations 

mph mile(s) per hour 

mR milliroentgen 

mrad millirad(s) 

mrem millirem(s) 

μS microsiemens 

MSA Metropolitan Statistical Area 

MSL mean sea level 

mSv millisievert(s) 

MT metric ton(s) (or tonne[s]) 

MTU metric ton(s) of uranium 

MUD municipal utilities district 

MW megawatt(s) 

MWd megawatt-day(s) 

MW(e) megawatt(s) electrical 

MW(t) megawatt(s) thermal 

NCI National Cancer Institute 

NCRP National Council on Radiation Protection & Measurements 

NEI Nuclear Energy Institute 

NEPA National Environmental Policy Act of 1969, as amended 

NERC North American Electric Reliability Corporation 

NESC National Electric Safety Code 

NHPA National Historic Preservation Act of 1966, as amended 

NIEHS National Institute of Environmental Health Sciences 

NINA Nuclear Innovation North America 

NMFS National Marine Fisheries Services 

NMM navigation mile marker 

NOAA National Oceanic and Atmospheric Administration 
NUREG-1937 xxxviii February 2011 

NOx nitrogen oxide 

NPDES National Pollutant Discharge Elimination System 

NPS National Park Service 

NRC U.S. Nuclear Regulatory Commission 

NRG NRG South Texas LP 

NRHP National Register of Historic Places 

NSR new source review 

NTF Nuclear Training Facility 

OCS outer continental shelf 

ODCM offsite dose calculation manual 

OSF Onsite Staging Facility 

OSGSF Old Steam Generator Storage Facility 

OSHA Occupational Safety and Health Administration 

OW observation well 

PAM primary amoebic meningoencephalitis 

pCi picocuries 

pCi/L picocuries per liter 

PGC Power Generation Company 

PIR Public Interest Review 

PM particulate matter 

PM2.5 particulate matter with a diameter of 2.5 microns or less 

PM10 particulate matter with a diameter of 10 microns or less 

PNNL Pacific Northwest National Laboratory 

POSGCD Post Oak Savannah Groundwater Conservation District 

ppt parts per thousand 

PSD prevention of significant deterioration 

PUCT Public Utility Commission of Texas 

PWR pressurized water reactors 

RAI request for additional information 

RCRA Resource Conservation and Recovery Act of 1976, as amended 

RCRWPG Region C Regional Water Planning Group 

RCW Reactor Building Cooling Water 

RE refueling 

rem roentgen equivalent man (a special unit of radiation dose) 

REMP radiological environmental monitoring program 

RIMS Regional Input-Output Model System 

RMPF Reservoir Makeup Pumping Facility 

RMR reliability must run 

ROD Record of Decision 
February 2011 xxxix NUREG-1937 

ROI region of interest 

ROW right of way 

RRGCD Red River Groundwater Conservation District 

RSICC Radiation Safety Information Computational Center 

RSW Reactor Service Water 

RV recreational vehicle 

Ryr reactor-year 

s second(s) 

SACTI Seasonal and Annual Cooling Tower Impacts 

SAMA severe accident mitigation alternatives 

SAMDA severe accident mitigation design alternatives 

SAWS San Antonio Water System 

SCR selective catalytic reduction 

SECPOP 2000 Sector Population, Land Fraction, and Economic Estimation Program 

SER Safety Evaluation Report 

SGIA signed generation interconnection agreement 

SHPO State Historic Preservation Officer 

SO2 sulphur dioxide 

SOx sulphur oxide 

STP South Texas Project Electric Generating Station 

STPEGS STP Electric Generating Station 

STPNOC STP Nuclear Operating Company 

SUV sport utility vehicle 

Sv sievert 

SWMS solid waste management system 

SWPPP Stormwater Pollution Prevention Plan 

TAC Texas Administrative Code 

TAMUG Texas A&M University at Galveston 

TBEG Texas Bureau of Economic Geology 

TBq terabecquerel(s) 

TCC Texas Central Company 

TCEQ Texas Commission on Environmental Quality 

TCMP Texas Coastal Management Plan 

TDCJ Texas Department of Criminal Justice 

TDHCA Texas Department of Housing and Community Affairs 

TDS total dissolved solids 

TDSHS Texas Department of State Health Services 

TEA Texas Education Agency 

TEDE total effective dose equivalent 
NUREG-1937 xl February 2011 

Texas RE Texas Reliability Entity 

THC Texas Historical Commission 

TIS Texas Interconnected System 

TLD thermoluminescent dosimeter 

TMDL total maximum daily load 

TPDES Texas Pollutant Discharge Elimination System 

TPWD Texas Parks and Wildlife Department 

TPWP Texas Prairie Wetlands Project 

TRAGIS Transportation Routing Analysis Geographic Information System 

TRC Texas Railroad Commission 

TSECO Texas State Energy Conservation Office 

TSHA Texas State Historical Association 

TWC Texas Water Code 

TWDB Texas Water Development Board 

TX Texas 

TxDOT Texas Department of Transportation 

U3O8 triuranium octaoxide (“yellowcake”) 

UF6 uranium hexafluoride 

UFSAR Updated Final Safety Analysis Report 

UHS Ultimate Heat Sink 

UMTRI University of Michigan Transportation Research Institute 

UO2 uranium oxide 

USACE U.S. Army Corps of Engineers 

USC United States Code 

USCB U.S. Census Bureau 

USGS U.S. Geological Survey 

VOC volatile organic compound 

WCS Waste Control Specialists, LLC 

WHO World Health Organization 

WMA Wildlife Management Area 

WSEC White Stallion Energy Center 

WSWTS West Sanitary Waste Treatment System 

WCID Water Control and Improvement District 

χ/Q atmospheric dispersion values 

yd yard(s) 

yd3

 cubic yard(s) 

yr year(s) 
February 2011 1-1 NUREG-1937 

1.0 Introduction 

By letter dated September 20, 2007, the U.S. Nuclear Regulatory Commission (NRC or the 

Commission) received an application from STP Nuclear Operating Company (STPNOC) for 

combined construction permits and operating licenses (combined licenses or COLs) for South 

Texas Project Electric Generating Station (STP) Units 3 and 4. The review team’s evaluation is 

based on the October 2010 revision (Revision 4) to the application, responses to requests for 

additional information, and supplemental information. 

The location of the proposed Units 3 and 4 is approximately 2000 ft northwest of the existing 

STP Units 1 and 2. The STP site and existing facilities are owned by NRG Energy, Inc. (NRG); 

City Public Service Board of San Antonio, Texas (CPS Energy); and the City of Austin, Texas. 

It is planned that STP Unit 3 would be owned by Nuclear Innovation North America (NINA) 

Texas 3 LLC and CPS Energy, and STP Unit 4 would be owned by NINA Texas 4 LLC and CPS 

Energy (STPNOC 2010a). STPNOC would be the licensed operator for the proposed Units 3 

and 4, as it currently is for the existing Units 1 and 2. In its application, STPNOC specified the 

certified U.S. Advanced Boiling Water Reactor (ABWR), as modified by STPNOC’s proposed 

amendment to the ABWR (STPNOC 2010b), as the proposed reactor design for Units 3 and 4. 

By letter dated January 19, 2011 (STPNOC 2011), STPNOC notified the NRC that its 

organizational arrangement was changing such that the lead applicant for STP Units 3 and 4 

would be NINA, with STPNOC remaining as the operator. With the change, NINA would 

assume responsibility for the design and construction of STP Units 3 and 4 and STPNOC would 

be the operator and license holder for both new units. Throughout this environmental impact 

statement (EIS), the acronym “STPNOC” means the lead applicant or lead licensee responsible 

for design and construction (i.e., NINA) or operations (i.e., STPNOC), depending upon the 

context of the discussion. 

On March 9, 2010, STPNOC submitted a Department of the Army Permit application (STPNOC 

2010c) to the U.S. Army Corps of Engineers (Corps) Galveston District for activities associated 

with constructing and operating STP Units 3 and 4. On March 25, 2010, the Corps published a 

public notice pursuant to Section 404 of the Federal Water Pollution Control Act (Clean Water 

Act) and Section 10 of the Rivers and Harbors Appropriation Act of 1899. The Corps is 

participating with the NRC in preparing this EIS as a cooperating agency. 

The proposed actions related to the STP Units 3 and 4 application are (1) NRC issuance of 

COLs for construction and operation of two new nuclear units at the STP site; and (2) the Corps 

issuance of a permit pursuant to Section 404 of the Clean Water Act and Section 10 of the 

Rivers and Harbors Act. The permit application to the Corps requests authorization to expand 

an existing barge slip on the Colorado River and to culvert and fill waters of the United States 

for the purpose of constructing a heavy haul road on the site.
Introduction 

NUREG-1937 1-2 February 2011 

1.1 Background 

A COL is a Commission approval for the construction and operation of a nuclear power facility. 

NRC regulations related to COLs are found primarily in Title 10 of the Code of Federal 

Regulations (CFR) Part 52, Subpart C. 

Section 102 of the National Environmental Policy Act of 1969, as amended (NEPA) 

(42 USC 4321 et seq.), requires preparation of an EIS for major Federal actions that 

significantly affect the quality of the human environment. The NRC has implemented 

Section 102 of NEPA in 10 CFR Part 51. Further, in 10 CFR 51.20, the NRC has determined 

that the issuance of a COL under 10 CFR Part 52 is an action that requires an EIS. 

According to 10 CFR 52.80(b), a COL application must contain an Environmental Report (ER). 

The ER provides the applicant’s input to the NRC’s EIS. NRC regulations related to ERs and 

EISs are found in 10 CFR Part 51. Part 3 of STPNOC’s application contains the ER, which 

provides a description of the proposed actions related to the application and the applicant’s 

analysis of the potential environmental impacts of construction and operation of proposed 

Units 3 and 4. 

The STPNOC license application references the certified U.S. ABWR design (STPNOC 2010a; 

10 CFR Part 52, Appendix A), as modified by a proposed amendment to the ABWR design 

certification (STPNOC 2010b) that is being sought by STPNOC to address the requirements of 

10 CFR 50.150 on the ability of the design to withstand the impact of a large commercial 

aircraft. STPNOC referenced this proposed amendment in Revision 4 of its COL application, 

dated October 5, 2010. Subpart B of 10 CFR Part 52 contains NRC regulations related to 

standard design certifications. The referenced certified ABWR Design Control Document was 

approved by the NRC in March 1997 and the final design certification rule was published in the 

Federal Register (FR) on May 12, 1997 (62 FR 25827). This EIS accounts for the referenced 

ABWR design, as modified by STPNOC’s proposed amendment to 10 CFR Part 52, Appendix 

A. Where appropriate, this EIS incorporates the results of the ABWR design review. 

1.1.1 Application and Review 

The purpose of the STPNOC application is to obtain COLs to construct and operate a baseload 

nuclear power plant comprised of two new reactors. In addition to the COLs, STPNOC must 

obtain and maintain permits from other Federal, State, and local agencies and permitting 

authorities. The purpose of STPNOC’s requested Corps action is to obtain a permit to perform 

regulated activities that would impact waters of the United States. 
Introduction 

February 2011 1-3 NUREG-1937 

1.1.1.1 NRC COL Application Review 

STPNOC submitted an ER as part of its COL application (STPNOC 2010d). The ER focuses on 

the environmental effects of construction and operation of two ABWR units. The NRC 

regulations setting standards for review of a COL application are listed in 10 CFR 52.81. 

Detailed procedures for conducting the environmental portion of the review are found in 

guidance set forth in NUREG-1555, Environmental Standard Review Plan (ESRP) (NRC 2000) 

and recent updates, hereafter referred to as the ESRP. Additional guidance on conducting 

environmental reviews is provided in the NRC Staff Memorandum Addressing Construction and 

Preconstruction, Greenhouse Gas Issues, General Conformity Determinations, Environmental 

Justice, Need for Power, Cumulative Impact Analysis, and Cultural/Historical Resources 

Analysis Issues in Environmental Impact Statements (NRC 2010a). 

In this EIS, the review team evaluates the environmental effects at the STP site of two ABWR 

reactors, each with thermal power ratings of 3926 MW(t). The new units would use a closedloop cooling water system that would withdraw and discharge water from and to the Main 

Cooling Reservoir. In addition to considering the environmental effects of the proposed action, 

the NRC considers alternatives to the proposed action including the no-action alternative and 

the construction and operation of new reactors at alternative sites. Also, the benefits of the 

proposed action (e.g., need for power) and measures and controls to limit adverse impacts are 

evaluated. STPNOC’s proposed action to construct and operate two new nuclear units includes 

requests for exemptions from the ABWR design certification (DC) under 10 CFR 52.93. The 

environmental impacts of the requested exemptions are addressed in this EIS. The technical 

analysis for each DC exemption will be included in the NRC’s Final Safety Evaluation Report 

(SER), including a recommendation for approval or denial of each exemption. 

Upon acceptance of the STPNOC application, the NRC began the environmental review 

process by publishing in the Federal Register on December 21, 2007, a Notice of Intent to 

prepare an EIS and conduct scoping (72 FR 72774). On February 5, 2008, the NRC held two 

public scoping meetings in Bay City, Texas, to obtain public input on the scope of the 

environmental review and contacted Federal, State, Tribal, regional, and local agencies to solicit 

comments. A listing of the agencies and organizations contacted is provided in Appendix B. 

The staff reviewed the comments received during scoping and responses were written for each 

comment. In-scope scoping comments and responses are included in Appendix D. A complete 

listing of the scoping comments and responses is documented in the South Texas Project 

Combined License Scoping Summary Report (NRC 2008). 

To gather information and to become familiar with the sites and their environs, the NRC and its 

contractor Pacific Northwest National Laboratory (PNNL) visited the STP site in February 2008 

and the Allens Creeks alternative site in March 2008. In August 2009, the NRC and PNNL 

visited the Red 2 and Trinity 2 alternative sites. During the site visits, the NRC staff met with 
Introduction 

NUREG-1937 1-4 February 2011 

STPNOC staff, public officials, and the public. Documents related to the STP site and 

alternatives sites were reviewed and are listed as references where appropriate. 

To guide its assessment of the environmental impacts of a proposed action or alternative 

actions, the NRC has established a standard of significance for impacts based on Council on 

Environmental Quality guidance (40 CFR 1508.27). Table B-1 of 10 CFR Part 51, Subpart A, 

Appendix B, provides the following definitions of the three significance levels established by the 

NRC – SMALL, MODERATE, and LARGE: 

SMALL – Environmental effects are not detectable or are so minor that they will neither 

destabilize nor noticeably alter any important attribute of the resource. 

MODERATE – Environmental effects are sufficient to alter noticeably, but not to 

destabilize, important attributes of the resource. 

LARGE – Environmental effects are clearly noticeable and are sufficient to destabilize 

important attributes of the resource. 

This EIS presents the review team’s analysis, which considers and weighs the environmental 

impacts of the proposed action at the STP site, including the environmental impacts associated 

with constructing and operating reactors at the site, the impacts of constructing and operating 

reactors at alternative sites, the environmental impacts of alternatives to granting the COLs, and 

the mitigation measures available for reducing or avoiding adverse environmental effects. This 

EIS also provides the NRC staff’s recommendation to the Commission regarding the issuance 

of COLs for proposed Units 3 and 4 at the STP site. 

The draft EIS was published on March 19, 2010 (NRC 2010b). A 75-day comment period 

commenced on March 26, 2010, when the U.S. Environmental Protection Agency’s (EPA’s) 

Notice of Availability of the draft EIS appeared in the Federal Register (75 FR 14594), to allow 

members of the public and agencies to comment on the results of the environmental review. 

Two public meetings were held in Bay City, Texas, on May 6, 2010, to describe the preliminary 

results of the environmental review, respond to questions, and receive comments on the draft 

EIS. When the comment period ended on June 9, 2010, the review team considered all of the 

comments received. All comments received on the draft EIS are included in Appendix E. 

Changes made in response to public comments and other substantive changes are identified by 

change bars in the margins of this final EIS. 

1.1.1.2 Corps Permit Application Review 

The Corps is part of the review team that makes a determination based on the three 

significance levels established by the NRC; however, the Corps’ independent Record of 

Decision (ROD) regarding the aforementioned permit application will reference the analyses in 

the EIS and present any additional information required by the Corps to support its permit 
Introduction 

February 2011 1-5 NUREG-1937 

decision. The Corps’ role as a cooperating agency in the preparation of this EIS is to ensure 

that the information presented is adequate to fulfill the requirements of Corps regulations 

applicable to construction of the preferred alternative identified in the EIS. The Clean Water Act 

Section 404(b)(1) Guidelines for Specification of Disposal Sites for Dredged or Fill Material 

(40 CFR Part 230), which contains the substantive environmental criteria used by the Corps in 

evaluating discharges of dredged or fill material into waters of the United States, and the Corps’ 

Public Interest Review (PIR) (33 CFR 320.4), direct the Corps to consider a number of factors 

as part of a balanced process. A discussion of those factors is provided below. The Corps’ PIR 

will be part of its permit decision document and thus will not be addressed in the EIS. 

This EIS includes the Corps’ evaluation of construction and maintenance activities that impact 

waters of the United States. The Corps’ permit decision will reflect the national concern for both 

protection and use of important resources. The benefit, which reasonably may be expected to 

increase from the proposal, must be balanced against its reasonably foreseeable detriments. 

Public interest factors that may be relevant to the proposal will be considered. These factors 

include conservation, economics, aesthetics, general environmental concerns, wetlands, historic 

and cultural resources, fish and wildlife values, flood hazards, floodplain values, land use, 

navigation, shore erosion and accretion, recreation, water supply, water quality, energy needs, 

safety, food and fiber production, mineral needs, considerations of property ownership, and 

cumulative impacts thereof. Evaluation of the impact on the public interest will include 

application of the guidelines promulgated by the Administrator, EPA, under authority of 

Section 404(b) of the Clean Water Act. The Corps will address these issues in its permit 

decision document. 

As part of the Corps’ permit evaluation process, the Corps issued a public notice on March 25, 

2010, to solicit comments from the public about STPNOC’s proposal to perform site preparation 

activities and construct supporting facilities at the STP site. Comments received on the Corps’ 

public notice are provided in Appendix K of this EIS. 

1.1.2 Preconstruction Activities 

In a final rule dated October 9, 2007, “Limited Work Authorizations for Nuclear Power Plants” 

(72 FR 57416), the Commission defined “construction” as those activities within its regulatory 

purview as defined in 10 CFR 51.4. Many of the activities required to construct a nuclear power 

plant are not part of the NRC action to license the plant. Activities associated with building the 

plant that are not within the purview of the NRC action are grouped under the term 

“preconstruction.” Preconstruction activities include clearing and grading, excavating, erection 

of support buildings and transmission lines, and other associate activities. These 

preconstruction activities may take place before the application for a COL is submitted, during 

the review of a COL application, or after a COL is granted. Although preconstruction activities 

are outside the NRC’s regulatory authority, nearly all of them are within the regulatory authority 

of local, State, or other Federal agencies. 
Introduction 

NUREG-1937 1-6 February 2011 

Because the preconstruction activities are not part of the NRC action, their impacts are not 

reviewed as a direct effect of the NRC action. Rather, the impacts of the preconstruction 

activities are considered in the context of cumulative impacts. In addition, certain 

preconstruction activities that propose to construct structures in and under navigable waters and 

to discharge dredged, excavated, and/or fill material into waters of the United States, including 

jurisdictional wetlands that require permits from the Corps, are viewed by the Corps as direct 

effects related to their Federal permitting action. Chapter 4 describes the relative magnitude of 

impacts related to construction and preconstruction activities. 

1.1.3 Cooperating Agencies 

NEPA lays the groundwork for coordination between the lead agency preparing an EIS and 

other Federal agencies that may have special expertise regarding an environmental issue or 

jurisdiction by law. These other agencies are referred to as “cooperating agencies.” 

Cooperating agencies have the responsibility to assist the lead agency through early 

participation in the NEPA process, including scoping, by providing technical input to the 

environmental analysis, and by making staff support available as needed by the lead agency. 

Most proposed nuclear power plants require a permit from the Corps, where impacts are 

proposed to waters of the United States, in addition to a license from the NRC. Therefore, the 

NRC and the Corps decided that the most effective and efficient use of Federal resources in the 

review of nuclear power projects would be achieved by a cooperative agreement. On 

September 12, 2008, the NRC and the Corps signed a Memorandum of Understanding (MOU) 

regarding the review of nuclear power plant license applications (Corps and NRC 2008). 

Therefore, the Galveston District of the Corps is participating as a cooperating agency as 

defined in 10 CFR Part 51.14. 

As described in the MOU, the NRC is the lead Federal agency, and the Corps is a cooperating 

agency in the development of the EIS. Under Federal law, each agency has jurisdiction related 

to portions of the proposed project as major Federal actions that could significantly affect the 

quality of the human environment. The goal of this cooperative agreement is the development 

of one EIS that serves the needs of the NRC license decision process and the Corps permitdecision process. While both agencies must comply with the requirements of NEPA, both 

agencies also have mission requirements that must be met in addition to the NEPA 

requirements. The NRC makes license decisions under the Atomic Energy Act of 1954, as 

amended (42 USC 2011 et seq.), and the Corps makes permit decisions under the Rivers and 

Harbors Appropriation Act of 1899 and the Clean Water Act. The Corps is cooperating with the 

NRC to ensure that the information presented in the NEPA documentation is adequate to fulfill 

the requirements of Corps regulations, the EPA’s Clean Water Act Section 404(b)(1) guidelines, 

which contain the substantive environmental criteria used by the Corps in evaluating discharges 

of dredged or fill material into waters of the United States, and the Corps PIR process. 
Introduction 

February 2011 1-7 NUREG-1937 

As a cooperating agency, the Corps is part of the NRC review team, involved in all aspects of 

the environmental review, including scoping, public meetings, public comment resolution, and 

EIS preparation. For the purposes of assessment of environmental impact under NEPA, the 

EIS uses the SMALL/MODERATE/LARGE criteria discussed in Section 1.1.1.1 of this EIS; this 

approach has been vetted by the Council on Environmental Quality when the NRC established 

its environmental review framework for the renewal of operating licenses. A cooperating agency 

may adopt the EIS of a lead Federal agency without recirculating it when the cooperating 

agency concludes, after an independent review of the EIS, that its comments and suggestions 

have been satisfied and issues a ROD. The goal of the process is that the Corps will have all 

the information necessary to make a permit decision when the final EIS is issued. However, it is 

possible that the Corps may still need some information from the applicant to complete the 

permit documentation, information that the applicant could not make available by the time of 

final EIS issuance. 

1.1.4 Concurrent NRC Reviews 

In reviews that are separate from, but parallel to, the EIS process, the NRC analyzes the safety 

characteristics of the proposed site and emergency planning information. These analyses are 

documented in a SER issued by the NRC. The SER presents the conclusions reached by the 

NRC regarding (1) whether there is reasonable assurance that two ABWR reactors can be 

constructed and operated at the STP site without undue risk to the health and safety of the 

public, (2) whether the emergency preparedness program meets the applicable requirements in 

10 CFR Part 50, 10 CFR Part 52, 10 CFR Part 73, and 10 CFR Part 100, and (3) whether site 

characteristics are such that adequate security plans and measures as referenced in the above 

CFR Parts can be developed. Preparation of the final SER for the STPNOC COL application is 

ongoing. 

STPNOC submitted an application to amend the design certification rule for the ABWR by letter 

dated June 30, 2009 (STPNOC 2009b). The purpose of the amendment is to demonstrate 

compliance with the requirements in 10 CFR 50.150, the Commission’s new aircraft impact 

assessment (AIA) rule. The AIA rule requires “...applicants for new nuclear power reactors to 

perform a design-specific assessment of the effects of the impact of a large, commercial aircraft. 

The applicant is required to use realistic analyses to identify and incorporate design features 

and functional capabilities to show, with reduced use of operator actions, that either the reactor 

core remains cooled or the containment remains intact, and either spent fuel cooling or spent 

fuel pool integrity is maintained.” The staff documented their safety findings in an SER. In 

addition, the staff prepared an environmental assessment (EA) that was limited to the review of 

the impact of the proposed amendment on the existing analysis of severe accident mitigation 

design alternatives for the ABWR design. The results of that EA are incorporated into this EIS. 

On January 20, 2011, the Commission published a proposed rule (76 FR 3540) to approve the 

proposed amendment to the ABWR design. If the NRC makes a final determination to approve 
Introduction 

NUREG-1937 1-8 February 2011 

the STPNOC amendment, it will do so in a final rule. The COL for Units 3 and 4 would not be 

issued until the design certification amendment is issued as a final rule. 

In addition to the COL review, STPNOC submitted a request to the NRC for a limited work 

authorization (LWA), in accordance with 10 CFR 50.10(d), for construction of permanent crane 

foundation retaining walls. In its request dated November 16, 2009, STPNOC explained why it 

did not believe an LWA was required for this particular activity (STPNOC 2009a). The NRC 

responded on January 08, 2010, that STPNOC would need an LWA for the retaining walls and 

therefore must either (1) submit a complete LWA request, (2) submit a request for an 

exemption, or (3) delay construction of the retaining walls until the COLs have been issued for 

Units 3 and 4 (NRC 2010c). STPNOC, in a letter dated February 2, 2010, withdrew their LWA 

request and formally requested an exemption (STPNOC 2010e). On March 23, 2010, STPNOC 

submitted a revised request for an exemption from 10 CFR 50.10(a)(1), to the extent necessary 

for the NRC to authorize installation of the retaining walls (STPNOC 2010f), supplemented by 

additional information on July 21, 2010 (STPNOC 2010g). The NRC conducted a separate 

safety and environmental review for STPNOC’s exemption request. The results of that 

environmental review were issued in an EA, published in the Federal Register on November 3, 

2010 (75 FR 67784). On November 5, 2010, the NRC granted STPNOC an exemption from 10 

CFR 50.10 to begin construction activities related to the installation of the crane foundation 

retaining walls (NRC 2010d). 

By letter dated October 25, 2010, STPNOC submitted an application to the NRC for renewal of 

the operating licenses of STP Units 1 and 2 (STPNOC 2010h). As part of that application 

review process, the NRC will analyze the environmental impacts of renewing the license for an 

extended period of operation and document its analysis in an EIS. The NRC will also evaluate 

whether the effects of aging on plant equipment will be managed such that Units 1 and 2 can be 

operated during the period of extended operation without undue risk to the health and safety of 

the public and will document its conclusions in an SER. 

1.2 The Proposed Federal Actions 

The proposed NRC Federal action is issuance, under the provisions of 10 CFR Part 52, of 

COLs for authorizing the construction and operation of two new ABWR units at the STP site. 

This EIS provides the NRC’s analyses of the environmental impacts that could result from 

building and operating two proposed new units at the STP site or at one of the three alternative 

sites. These impacts are analyzed to determine if the proposed site is suitable for the addition 

of the new units and whether any of the alternative sites is considered obviously superior to the 

proposed site. 

The Corps’ Federal action is the decision whether to issue a permit pursuant to Section 404 of 

the Clean Water Act and Section 10 of the Rivers and Harbors Act of 1899 to authorize certain 

construction activities potentially affecting waters of the United States based on an evaluation of 
Introduction 

February 2011 1-9 NUREG-1937 

the probable impacts, including cumulative impacts, of the proposed construction activities on 

the public interest. These impacts are analyzed by the Corps to determine whether there is a 

practicable alternative with less adverse impact on the aquatic ecosystem provided that the 

alternative does not have other significant adverse consequences. 

1.3 The Purpose and Need for the Proposed Actions 

The continued growth of residential and commercial development in Texas has created an 

increased demand for electrical power. The purpose of this proposed action, authorization of 

the construction and operation of two ABWR units at the STP site, is to provide additional 

baseload electrical generation capacity for use in the owner’s current markets and/or for 

potential sale on the wholesale market. The need for additional baseload power is discussed in 

Chapter 8 of this EIS. 

Two COLs from the NRC are needed to construct and operate the proposed two new units. 

Preconstruction and certain long lead-time activities, such as ordering and procuring certain 

components and materials necessary to construct the plant, may begin before the COLs are 

granted. STPNOC must obtain and maintain permits or authorizations from other Federal, 

State, and local agencies, and permitting authorities before undertaking certain activities. The 

ultimate decision whether or not to build the new units and the schedule for building are not 

within the purview of the NRC or the Corps and would be determined by the license holder if the 

authorizations are granted. 

1.4 Alternatives to the Proposed Actions 

Section 102(2)(C)(iii) of NEPA states that EISs are to include a detailed statement analyzing 

alternatives to the proposed action. The NRC regulations for implementing Section 102(2) of 

NEPA provide for including in an EIS a chapter that discusses the environmental impacts of the 

proposed action and the alternatives (10 CFR Part 51, Subpart A, Appendix A). Chapter 9 of 

this EIS addresses five categories of alternatives to the proposed action: (1) the no-action 

alternative, (2) energy source alternatives, (3) alternative sites, (4) system design alternatives, 

and (5) onsite alternatives to reduce impacts to aquatic resources. 

In the no-action alternative, the proposed action would not go forward. The NRC could deny 

STPNOC’s request for the COLs. If the request was denied, the construction and operation of 

the two new units at the STP site would not occur nor would any benefits intended by the 

approved COLs be realized. Energy source alternatives include alternative energy sources, 

focusing on those alternatives that could generate baseload power. The alternative site 

selection process to determine alternate site locations for comparison with the STP site is 

addressed below. System design alternatives include heat dissipation and circulating water 

systems, intake and discharge structures, and water-use and treatment systems. Finally, onsite 
Introduction 

NUREG-1937 1-10 February 2011 

alternatives evaluated by the Corps to reduce potential impacts to waters of the United States 

including jurisdictional wetlands and shoreline resources, are described. 

In its ER, STPNOC defines a region of interest for use in identifying and evaluating potential 

sites for power generation. Using this process, the applicant reviewed multiple sites and 

identified nine primary sites for this project from which the alternative sites were selected. The 

staff evaluated the region of interest, the process by which alternative sites were selected, and 

the environmental impacts of construction and operation of a new power reactor at those sites 

using reconnaissance-level information. The alternative sites selected from the primary sites 

include two privately owned greenfield sites and a greenfield site that is partially owned by 

NRG Energy, Inc. and was previously considered for the location of a nuclear power plant. The 

objective of the comparison of environmental impacts is to determine if any of the alternative 

sites are obviously superior to the proposed STP site. 

As part of the evaluation of permit applications subject to Section 404 of the Clean Water Act, 

the Corps is required by regulation to apply the criteria set forth in the 404(b)(1) guidelines 

(33 USC 1344; 40 CFR Part 230). These guidelines establish criteria that must be met in order 

for the proposed activities to be permitted pursuant to Section 404. Specifically, these 

guidelines state, in part, that no discharge of dredged or fill material shall be permitted if there is 

a practicable alternative to the proposed discharge that would have less adverse impact on the 

aquatic ecosystem provided the alternative does not have other significant adverse 

consequences (40 CFR 230.10(a)). 

1.5 Compliance and Consultations 

Before building and operating new units, STPNOC is required to obtain certain Federal, State, 

and local environmental permits, as well as meet applicable statutory and regulatory 

requirements. STPNOC (2010d) provided a list of environmental approvals and consultations 

associated with the proposed Units 3 and 4. Potential authorizations, permits, and certifications 

relevant to the proposed COLs are included in Appendix H. The NRC staff reviewed the list and 

contacted the appropriate Federal, State, Tribal, and local agencies to identify any consultation, 

compliance, permit, or significant environmental issues of concern to the reviewing agencies 

that may affect the acceptability of the STP site for building and operating the two proposed

ABWR units. A chronology of the correspondence is provided as Appendix C. A list of the key 

consultation correspondence is provided as Appendix F, which also contains a biological 

assessment and an essential fish habitat assessment. 

1.6 References 

10 CFR Part 50. Code of Federal Regulations, Title 10, Energy, Part 50, “Domestic Licensing of 

Production and Utilization Facilities.” 
Introduction 

February 2011 1-11 NUREG-1937 

10 CFR Part 51. Code of Federal Regulations, Title 10, Energy, Part 51, “Environmental 

Protection Regulations for Domestic Licensing and Related Regulatory Functions.” 

10 CFR Part 52. Code of Federal Regulations, Title 10, Energy, Part 52, “Licenses, 

Certifications, and Approvals for Nuclear Power Plants.” 

10 CFR Part 73. Code of Federal Regulations, Title 10, Energy, Part 73, “Physical Protection of 

Plants and Materials.” 

10 CFR Part 100. Code of Federal Regulations, Title 10, Energy, Part 100, “Reactor Site 

Criteria.” 

33 CFR Part 320. Code of Federal Regulations, Title 33, Navigation and Navigable Waters, 

Parts 320-330, “General Regulatory Policies to Nationwide Permit Program. 

40 CFR Part 230. Code of Federal Regulations, Title 40, Protection of Environment, 

“Section 404(b)(1) Guidelines for Specification of Disposal Sites for Dredged or Fill Material.” 

40 CFR Part 1508. Code of Federal Regulations, Title 40, Protection of Environment, 

Part 1508, “Terminology and Index.” 

62 FR 25827. May 12, 1997. “Standard Design Certification for the U.S. Advanced Boiling 

Water Reactor Design.” Federal Register. U.S. Nuclear Regulatory Commission.

72 FR 57416. October 9, 2007. “Limited Work Authorizations for Nuclear Power Plants.” 

Federal Register. U.S. Nuclear Regulatory Commission. 

72 FR 72774. December 21, 2007. “South Texas Project Nuclear Operating Company South 

Texas Project Site, Units 3 & 4; Notice of Intent To Prepare an Environmental Impact Statement 

and Conduct Scoping Process.” Federal Register. U.S. Nuclear Regulatory Commission. 

75 FR 14594. March 26, 2010. “Environmental Impacts Statements; Notice of Availability.” 

Federal Register. U.S. Environmental Protection Agency. 

75 FR 67784. November 3, 2010. "STP Nuclear Operating Company South Texas Project 

Electric Generating Station, Units 3 and 4 Request for Exemption Environmental Assessment 

and Finding of No Significant Impact." Federal Register. U.S. Nuclear Regulatory Commission. 

76 FR 3540. January 20, 2011. “Proposed Rules: U.S. Advanced Boiling Water Reactor 

Aircraft Impact Design Certification Amendment.” Federal Register. U.S. Nuclear Regulatory 

Commission. 

Atomic Energy Act of 1954. 42 USC 2011, et seq. 
Introduction 

NUREG-1937 1-12 February 2011 

Federal Water Pollution Control Act (Clean Water Act). 33 USC 1251, et seq. 

National Environmental Policy Act of 1969, as amended (NEPA). 42 USC 4321, et seq. 

Rivers and Harbors Appropriation Act of 1899, as amended. 33 USC 403, et seq. 

South Texas Project Nuclear Operating Company (STPNOC). 2009a. Letter from Mark 

McBurnett, STPNOC, to NRC dated November 16, 2009, “Request for a Limited Work 

Authorization for Installation of Crane Foundation Retaining Walls.” Accession 

No. ML093230143. 

South Texas Project Nuclear Operating Company (STPNOC). 2009b. Letter from Mark 

McBurnett, STPNOC, to NRC, dated June 30, 2009, “Application to Amend the Design 

Certification Rule for the U.S. Advanced Boiling Water Reactor (ABWR).” Accession No. 

ML092040048. 

South Texas Project Nuclear Operating Company (STPNOC). 2010a. South Texas Project 

Units 3 and 4 Combined License Application, Part 1, General and Financial Information. 

Revision 4, Bay City, Texas. Accession No. ML102860173. 

South Texas Project Nuclear Operating Company (STPNOC). 2010b. ABWR STP Aircraft 

Impact Assessment (AIA) Amendment. Revision 3, Bay City, Texas. Accession No 

ML102870017. 

South Texas Project Nuclear Operating Company (STPNOC). 2010c. Letter from Scott Head, 

STPNOC, to the U.S. Army Corps of Engineers Galveston District, dated March 9, 2010, “South 

Texas Project Units 3 and 4 Application for Department of Army Permit.” Accession 

No. ML102700237. 

South Texas Project Nuclear Operating Company (STPNOC). 2010d. South Texas Project 

Units 3 and 4 Combined License Application, Part 3, Environmental Report. Revision 4, Bay 

City, Texas. Accession No. ML102860592. 

South Texas Project Nuclear Operating Company (STPNOC). 2010e. Letter from Mark 

McBurnett, STPNOC, to NRC dated February 02, 2010, “Request for Exemption to Authorize 

Installation of Crane Foundation Retaining Walls.” Accession No. ML100350219. 

South Texas Project Nuclear Operating Company (STPNOC). 2010f. Letter from Mark 

McBurnett, STPNOC, to NRC dated March 23, 2010, “Request for Exemption to Authorize 

Installation of Crane Foundations Retaining Walls.” Accession No. ML100880055. 
Introduction 

February 2011 1-13 NUREG-1937 

South Texas Project Nuclear Operating Company (STPNOC). 2010g. Letter from Scott Head, 

STPNOC, to NRC dated July 21, 2010, “Revised Request for Exemption to Authorize 

Installation of Crane Foundations Retaining Walls.” Accession No. ML102070274. 

South Texas Project Nuclear Operating Company (STPNOC). 2010h. Letter from G.T. Powell, 

STPNOC, to NRC dated October 25, 2010, “South Texas Project Units 1 and 2 Docket Nos. 

STN 50-498, STN 50-499 License Renewal Application.” Accession No. ML103010257. 

South Texas Project Nuclear Operating Company (STPNOC). 2011. Letter from Mark 

McBurnett, STPNOC, to NRC, dated January 19, 2011, “Update to Change in Lead Applicant 

for STP 3 & 4.” Accession No. ML110250369. 

U.S. Army Corps of Engineers and U.S. Nuclear Regulatory Commission (Corps and NRC). 

2008. Memorandum of Understanding: Environmental Reviews Related to the Issuance of 

Authorizations to Construct and Operate Nuclear Power Plants. September 12, 2008. 

Accession No. ML082540354. 

U.S. Nuclear Regulatory Commission (NRC). 2000. Environmental Standard Review Plan —

Standard Review Plans for Environmental Reviews for Nuclear Power Plants. NUREG-1555, 

Vol. 1, Washington, D.C. Includes 2007 updates. 

U.S. Nuclear Regulatory Commission (NRC). 2008. South Texas Project Combined License 

Scoping Summary Report. Washington, D.C. Accession No. ML082260454. 

U.S. Nuclear Regulatory Commission (NRC). 2010a. Staff Memorandum from Scott Flanders, 

DSER Division Director, to Brent Clayton, RENV Branch Chief, dated December 10, 2010, 

“Addressing Construction and Preconstruction Activities, Greenhouse Gas Issues, General 

Conformity Determinations, Environmental Justice, Need for Power, Cumulative Impact 

Analysis, and Cultural/Historical Resources Analysis Issues In Environmental Impact 

Statements.” Accession No. ML100760503. 

U.S. Nuclear Regulatory Commission (NRC). 2010b. Draft Environmental Impact Statement for 

Combined Licenses (COLs) for South Texas Project Electric Generating Station Units 3 and 4 – 

Draft Report for Comment. NUREG-1937, Volumes 1 and 2. Washington, D.C. 

U.S. Nuclear Regulatory Commission (NRC). 2010c. Letter from Michael Johnson, NRC, to 

Mark McBurnett, STPNOC, dated January 8, 2010, “South Texas Project Nuclear Power Plant 

Units 3 and 4 Request for a Limited Work Authorization for Installation of Crane Foundation 

Retaining Walls.” Accession No. ML093350744. 
Introduction 

NUREG-1937 1-14 February 2011 

U.S. Nuclear Regulatory Commission (NRC). 2010d. Letter from Mark Tonacci, NRC, to Mark 

McBurnett, STPNOC, dated November 5, 2010, “South Texas Project Nuclear Power Plant 

Units 3 and 4 Exemption from the Requirements of Title 10 of the Code of Federal Regulations, 

Part 50, Section 50.10 (TAC NO. RG1056).” Accession No. ML102770454. 
February 2011 2-1 NUREG-1937 

2.0 Affected Environment 

The site proposed by STP Nuclear Operating Company (STPNOC) is located in a rural area of 

Matagorda County, Texas. STPNOC currently operates two nuclear generating units (existing 

Units 1 and 2) on the South Texas Project (STP) site. The site is located approximately 10 mi 

north of Matagorda Bay, 70 mi south-southwest of Houston, and 12 mi south-southwest of Bay 

City, Texas, along the west bank of the Colorado River. The proposed Units 3 and 4 location is 

described in Section 2.1, followed by descriptions of the land, water, ecology, socioeconomics, 

environmental justice, historic and cultural resources, air, geology, and radiological and 

nonradiological environment of the site presented in Sections 2.2 through 2.11, respectively. 

Section 2.12 examines related Federal projects, and references are presented in Section 2.13. 

2.1 Site Location 

STPNOC’s proposed location for Units 3 and 4 is wholly within the STP site, approximately 

1500 ft north and 2150 ft west of the center of the existing Units 1 and 2 containment buildings 

on the north side of the Main Cooling Reservoir (MCR), as shown in Figure 2-1 

(STPNOC 2010a). Bay City Census County Division (CCD) is the closest population center 

(more than 25,000 residents) to the proposed new units (STPNOC 2010a) (Figure 2-2). The 

STP property is approximately 12,220 ac and directly borders the west side of the Colorado 

River on the site’s east boundary. 

2.2 Land Use 

This section discusses existing conditions related to land-use issues on and in the vicinity 

(i.e., the area encompassed within a radius of 6 mi) of the STP site. Section 2.2.1 describes the 

site and the vicinity around the site. Section 2.2.2 discusses the existing transmission line 

corridors. Section 2.2.3 discusses the region, defined as the area within 50 mi of the site 

boundary. 

2.2.1 The Site and Vicinity 

The STP site comprises approximately 12,220 ac in an unincorporated area of Matagorda 

County, Texas. Land-use classifications of the STP site are shown in Figure 2-3. Landscape 

features and habitat types are shown in Figure 2-4. Land-use classifications within a 6-mi 

radius of the STP site are shown in Figure 2-5. 
Affected Environment 

NUREG-1937 2-2 February 2011 

Figure 2-1. STP Site and Proposed Plant Footprint (STPNOC 2010a) 
Affected Environment 

February 2011 2-3 NUREG-1937 

Figure 2-2. STP Site and Vicinity (STPNOC 2010a)
Affected Environment 

NUREG-1937 2-4 February 2011 Figure 2-3. Land-Use Classifications at STP Site (STPNOC 2010a)
February 2011 2-5 NUREG-1937 

 Affected Environment Figure 2-4. Landscape Features and Habitat Types of the STP Site (adapted from STPNOC 2010a) 
Affected Environment 

NUREG-1937 2-6 February 2011 Figure 2-5. Land-Use Classifications in the Vicinity of the STP Site (STPNOC 2010a)
Affected Environment 

February 2011 2-7 NUREG-1937 

The topography in the vicinity of the STP site is characterized by relatively flat coastal plain with 

farmland and pasture land predominating. Elevations generally range from 20 to 30 ft above 

mean sea level (MSL). Approximately 67 percent of the land within the 6-mi vicinity of the STP 

site is agricultural land; 15 percent is forest land; 11 percent is water; 1 percent is wetlands; 

4 percent is rangeland, grassland, or bottomland; 2 percent is urban; and less than 1 percent is 

barren land (STPNOC 2010a). 

The STP site contains two existing nuclear generating units, STP Units 1 and 2, which are 

licensed by the U.S. Nuclear Regulatory Commission (NRC) and have a combined net electric 

generating capacity of approximately 2500 MW(e). Unit 1 began commercial operation in March 

1988, and Unit 2 began commercial operation in March 1989. Together, the two existing 

nuclear units, other facilities such as the training facility, and onsite transmission line corridors 

occupy approximately 300 ac of the STP site (STPNOC 2010a). 

The MCR occupies approximately 7000 ac of the STP site, and about 1750 ac are currently 

occupied by Units 1 and 2 and associated facilities. The remainder of the site is undeveloped 

land or is used for agriculture and cattle grazing. Some of the undeveloped land located east of 

the MCR is leased for cattle grazing (STPNOC 2010a). Land use within the STP site is 

summarized in Table 2-1. 

Table 2-1. Land Use at the STP Site 

Land Use Category Acres Percentage 

bottomland 1176 9.6 

Units 1 and 2 construction spoils area 41 0.3 

Essential Cooling Pond 46 0.4 

existing facilities related to Units 1 and 2 300 2.5 

forested communities 53 0.4 

forested/mixed pastureland 91 0.7 

leased agricultural lands 536 4.4 

Main Cooling Reservoir 7000 57.3 

maintained and disturbed areas 468 3.8 

mixed grass communities 485 4.0 

scrub shrub communities 970 7.9 

wetlands 162 1.3 

reservoir levee systems 759 6.2 

dredge materials disposal area 133 1.1 

Total 12,220 

Source: STPNOC 2010a 
Affected Environment 

NUREG-1937 2-8 February 2011 

No zoning currently applies to the STP site (STPNOC 2010a). STPNOC has maintained its own 

land management plan for the STP site since 1995. Approximately 90 percent of the STP site, 

excluding the MCR and existing facilities, constitutes prime farmland (STPNOC 2010a). 

The owners of the STP site own or control all of the mineral interests within the STP site 

boundary. The owners also have the power to acquire any outstanding mineral interests 

needed for operation of the proposed nuclear units. The owners control the surface minerals 

and any drilling used to recover minerals. However, the owners have agreed to not exercise 

their right to use any area within the exclusion area boundary at the STP site for explorations or 

recovery of minerals, or convey or lease mineral rights to any third party, without obtaining 

STPNOC’s prior approval. There are mineral resources (e.g., sand and gravel, coal, oil, natural 

gas, ores) within the STP site boundary and within the 6-mi vicinity that are presently being 

exploited or are of known commercial value. There are two petroleum wells on the STP site that 

have been plugged and abandoned. There are also 7 petroleum wells, 26 natural gas wells, 

and 9 oil/gas wells within the 6-mi vicinity (STPNOC 2010a). 

The 46-ac Essential Cooling Pond (ECP) serves as the Ultimate Heat Sink (UHS) for existing 

STP Units 1 and 2 and is east of Units 1 and 2 (STPNOC 2010a). The Texas Prairie Wetlands 

Project is a managed 110-ac shallow wetland area that was constructed in the northeast portion 

of the STP site in 1996 to enhance the site for waterbirds (STPNOC 2010a). There are waters 

of the United States subject to Federal regulatory authority within the proposed building and 

laydown/spoils sites for proposed Units 3 and 4. 

The STP site is located along the west bank of the Colorado River. A barge slip on the 

Colorado River is located approximately 3.5 mi southeast of existing STP Units 1 and 2. The 

Colorado River is not a wild and scenic river as that term is defined at in 36 CFR 297.3. Small 

portions of the STP site near the Colorado River are within the 100-year and 500-year 

floodplains (STPNOC 2010a). 

Several sloughs flow through the STP site. One slough feeds 34-ac Kelly Lake, which is located 

in the northeast corner of the site (see Figure 2-2) (STPNOC 2010a). Little Robbins Slough is 

an intermittent stream located in a channel on the west side of the west embankment of the 

MCR (STPNOC 2010a). 

Access to the STP site is from farm-to-market (FM) roads FM 521 and FM 1468. FM 1468 

intersects FM 521 approximately 350 ft west of the main plant entrance (STPNOC 2010a). An 

inactive railroad spur approximately 9 mi long, runs north from the STP site to a commercial 

railroad line operated by the Union Pacific Railroad. No natural gas pipelines traverse the STP 

site (STPNOC 2008f). 

The Texas Parks and Wildlife Department (TPWD) operates the 7200-ac Mad Island Wildlife 

Management Area (WMA) located approximately 3 mi south of the STP site. There is a Lower 
Affected Environment 

February 2011 2-9 NUREG-1937 

Colorado River Authority (LCRA) park approximately 3 mi east of the STP site (see Figure 2-1). 

The 7063-ac Clive Runnells Family Mad Island Marsh Preserve is approximately 4 mi southwest 

of the STP site and contains both upland prairie and a variety of coastal wetlands (STPNOC 

2010a). The preserve is owned and operated by The Nature Conservancy of Texas. There are 

no schools, hospitals, or prisons within the vicinity of the STP site. 

Most of the STP site is located within the coastal management zone established by the Texas 

Coastal Management Program (TCMP) (STPNOC 2010a). As required by Section 307(c)(3)(A) 

of the Coastal Zone Management Act (CZMA) (16 USC 1451 et seq), STPNOC consulted with 

the Texas General Land Office to determine whether or not the proposed project would be 

consistent with the Texas Coastal Management Program. STPNOC submitted a consistency 

determination to the Texas Coastal Coordination Council in April 2008 for its review. The 

Council responded in a June 9, 2008, letter that no unavoidable adverse impacts had been 

found for proposed Units 3 and 4 and that the proposed project would therefore be consistent 

with the goals and policies of the TCMP (STPNOC 2010a). 

2.2.2 Transmission Lines 

Four transmission service providers currently serve the STP site: CenterPoint Energy, 

American Electric Power Texas Central Company, the City of Austin, and the City Public 

Service Board of San Antonio (STPNOC 2010a). The existing 345-kV switchyard at the STP 

site currently has nine 345-kV transmission lines that connect it to the utility grid. These nine 

lines occupy three corridors, identified as the Eastern, Western, and Northwestern (or Middle) 

corridors. The corridors originate at the STP site (STPNOC 2010a). The power transmission 

system for proposed Units 3 and 4 would not require new transmission lines or corridors, but 

would use five of the nine 345-kV transmission lines that currently connect to existing STP 

Units 1 and 2 (STPNOC 2010a). A portion of the system would be upgraded as discussed in 

Chapter 3. 

2.2.3 The Region 

The 50-mi region surrounding the STP site is shown in Figure 2-6. The STP site is 

approximately 12 mi south-southwest of Bay City, Texas, and 10 mi north of Matagorda Bay on 

the Gulf of Mexico. Bay City is the county seat of Matagorda County. Palacios is the other 

incorporated community in Matagorda County. No Tribal lands of Federally recognized Indian 

Tribal entities are located within the 50-mi region (STPNOC 2010a). 

All or portions of nine counties (Brazoria, Fort Bend, Wharton, Jackson, Victoria, Calhoun, 

Lavaca, Colorado, and Matagorda) are within 50 mi of the STP site (STPNOC 2010a). 
Affected Environment 

NUREG-1937 2-10 February 2011 Figure 2-6. Land-Use Classifications in STP 50-mi Region (STPNOC 2010a)
Affected Environment 

February 2011 2-11 NUREG-1937 

Within the region, approximately 61 percent of the land is agricultural, 18 percent forest, 

10 percent rangeland, 5 percent wetland, 2.5 percent urban or built-up, 2 percent freshwater 

bodies, and less than 1 percent is barren land (STPNOC 2010a). 

2.3 Water 

This section describes the hydrologic processes and water bodies in and around the STP site, 

the existing water use, and the quality of water in the vicinity of the proposed Units 3 and 4 site. 

This description is limited to those parts of the hydrosphere that may affect or be affected by 

building and operation of the proposed Units 3 and 4. Building activities will affect the Shallow 

Aquifer at the site. Building and operation activities would make use of groundwater from the 

Deep Aquifer. During operation of the proposed Units 3 and 4, the Colorado River would be the 

source of makeup water for normal plant operations, and groundwater would be used as the 

source for makeup water for the UHS of the proposed units, service water for Units 3 and 4, and 

water for sanitary and potable water systems. The Colorado River would receive water 

discharged from the MCR. The environment described in this section, therefore, includes 

(1) the Colorado River system upstream of the site, because (a) it is the source of runoff that 

sustains the flow in the river and would provide makeup water for normal plant operations and 

(b) future availability of water in the river may be affected by the amount of water allocated to 

Units 3 and 4; (2) the Colorado River System downstream of the site because downstream 

water availability and quality may be affected by water used by Units 3 and 4 and the water 

discharged from the MCR; (3) local water features at and adjacent to the site, and (4) the local 

and regional groundwater systems, because they are the source of water during the building 

and operation of Units 3 and 4. 

2.3.1 Hydrology 

This section describes the site-specific and regional hydrological features that could affect, or be 

affected by, building and operation of proposed Units 3 and 4. The hydrologic conditions at the 

proposed Units 3 and 4 site are described in Section 2.4 of the Final Safety Analysis Report 

(FSAR) (STPNOC 2010b). A summary of the hydrologic conditions of the proposed site is 

provided in Section 2.3 of the Environmental Report (ER) (STPNOC 2010a). The following 

descriptions are based on information from these sources and other publicly available sources 

of hydrological data (LCRWPG 2006; LCRA 2009a, b; USGS 2009a, b; TCEQ 2007, 2008a; 

Corps 2009b; TxDOT 2007). 

2.3.1.1 Surface-Water Hydrology 

Figure 2-7 shows the location of the STP site with respect to the Lower Colorado River Basin 

and the Colorado-Lavaca Basin. The Colorado River Basin (Figure 2-8) is approximately 
Affected Environment 

NUREG-1937 2-12 February 2011 

42,318 mi2 in size (LCRWPG 2006). The Lower Colorado River Basin is the portion 

downstream of Lake O.H. Ivie (Figure 2-8). Approximately 90 percent of the contributing area of 

the basin lies upstream of the Mansfield Dam located near Austin, Texas (LCRWPG 2006). The 

STP site is located on the west bank of the Colorado River at River Mile 14.6. The location of 

the site with respect to nearby cities, the Matagorda Bay, and the Gulf of Mexico is shown in 

Figure 2-9. The Matagorda Bay and the Gulf of Mexico are located approximately 12 and 15 mi 

to the south, respectively (Figure 2-10). The water surface elevations in the Colorado River 

near the site are subject to upstream release and tidal fluctuations. 

The mouth of the Colorado River where it flows into the Gulf of Mexico is located approximately 

28 mi east-northeast of Port O’Connor and approximately 48 mi west-southwest of Freeport 

(Figure 2-7). At both of these gulf coast cities, the National Oceanic and Atmospheric 

Administration (NOAA) maintains tide gauges. The mean tidal range, the difference between 

the mean high water and mean low water, at Freeport is 1.4 ft and the diurnal range, the 

difference between mean higher high water and mean lower low water, is 1.8 ft (NOAA 2009a). 

The corresponding values at the Port O’Connor tide gauge are 0.7 ft and 0.8 ft (NOAA 2009b). 

NOAA (2009c) estimated the long term sea-level rise to range from 1.1 to 1.8 ft/century at the 

Freeport tide gauge using data from 1954 to 2006. NOAA did not perform the corresponding 

estimate at the Port O’Connor tide gauge. 

On a longer-term scale, climate change is a subject of national and international interest. The 

recent compilation of the state of knowledge by the U.S. Global Change Research Program 

(GCRP), a Federal Advisory Committee, has been considered in preparation of this 

environmental impact statement (EIS). According to the GCRP, it is reasonably foreseeable 

that sea level rise may exceed 3 ft by the end of the century (GCRP 2009). Actual changes in 

shorelines would also be influenced by geological changes in shoreline regions (e.g., 

subsidence). The increase in sea level relative to the Colorado River bed, coupled with reduced 

streamflow (also due to climate change), would result in the salt water front in the Colorado 

River moving up towards the Reservoir Makeup Pumping Facility (RMPF). 

The discharge and water temperature in the Colorado River near the site are characterized by 

measurements made at the U.S. Geological Survey (USGS) gauge 08162500, Colorado River 

near Bay City, Texas. Streamflow discharge data at this gauge has been available since May 1, 

1948. The period of record for water quality sampling at this gauge spans October 16, 1974, 

through June 26, 2001. 
Affected Environment 

February 2011 2-13 NUREG-1937 

Figure 2-7. Location of the STP Site and the Adjacent Watersheds 
Affected Environment 

NUREG-1937 2-14 February 2011 

Figure 2-8. The Colorado River Basin 
Affected Environment 

February 2011 2-15 NUREG-1937 

Figure 2-9. Location of the STP Site with Respect to Nearby Cities, the Matagorda Bay, and 

the Gulf of Mexico 
Affected Environment 

NUREG-1937 2-16 February 2011 

Figure 2-10. Daily Mean Colorado River Discharge near Bay City, Texas (USGS 2009c) 

The mean annual discharge at the USGS gauge near Bay City, based on data for water years 

1949 through 2008, is estimated to be approximately 2629 cfs (USGS 2009a). Mean monthly 

discharges at the same location reveal that August is the driest month with approximately 

932 cfs of mean discharge, and June is the wettest month with approximately 4240 cfs of mean 

discharge (USGS 2009b). The daily discharge for the period of record for the USGS gauge 

near Bay City (USGS 2009c) is shown in Figure 2-10. The mean daily discharge for the period 

of record is 2613 cfs. 

Texas experiences frequent droughts (LCRWPG 2006). Droughts in Texas are primarily caused 

by formation of a stationary, high-pressure system called the Bermuda High that prevents 

passage of low-pressure fronts (LCRWPG 2006). Based on streamflow data at the USGS gauge 

near Bay City, the annual discharge during water years 1951 to 1956 ranged from 23 to 

48 percent of the mean annual discharge. During 1962 to 1967, the annual discharge ranged 

from 21 to 79 percent of the mean annual discharge. During 1983 to 1986, the annual discharge 

ranged from 25 to 72 percent of the mean annual discharge. During 1988 to 1991, the annual 

discharge ranged from 21 to 78 percent of the mean annual discharge. These episodes are 
Affected Environment 

February 2011 2-17 NUREG-1937 

examples of multi-year drought in the Colorado River Basin. Out of 55 years during 1948 

through 2008 for which annual discharges were measured by the USGS at the Bay City gauge, 

the annual discharge was less than 75 percent of mean annual discharge during 26 years. 

The streamflow in the Colorado River downstream of Austin, Texas, is influenced by releases 

from the Mansfield Dam. The LCRA operates six dams: Buchanan, Inks, Wirtz, Starcke, 

Mansfield, and Tom Miller (LCRA 2009b) that inundate the six highland lakes: Buchanan, Inks, 

Lyndon B. Johnson, Marble Falls, Travis, and Austin, respectively (Figure 2-11). Lake 

Buchanan has a storage capacity of 875,566 ac-ft at its normal operating level and is used for 

water supply and hydroelectric power generation. Lake Travis has a storage capacity of 

1,131,650 ac-ft at its normal operating level and is used for water supply, flood management, 

and hydroelectric power generation. The combined water storage capacity of the six highland 

lakes is 2,184,777 ac-ft (LCRA 2009b). 

The LCRA manages the Colorado River and Lakes Buchanan and Travis as a single system for 

water supply in the Lower Colorado River Basin (LCRA 2010). The two lakes are used to 

conserve water and inflows into the river below the highland lakes are used to meet 

downstream demand to the extent possible. Waters stored in the lakes are released only when 

downstream water rights cannot be met. Generally, LCRA does not release waters from any of 

the lakes exclusively for hydroelectric power generation. However, during emergency shortage 

of electricity or during times when such releases would provide other benefits, LCRA may 

release waters from the lakes (LCRA 2010). 

The floodplain in the Lower Colorado River Basin has a relatively flat gradient and is 

characterized by broad floodplains. Streamflow in the Colorado River is controlled by releases 

from the Mansfield Dam and remains relatively unaffected downstream. A description of 

existing water diversions downstream of the Mansfield Dam is provided in Section 2.3.2.1. 

The predominant surface water feature near the STP site is the MCR (Figure 2-9), an 

engineered cooling pond impounded by earthen embankments constructed on the natural 

ground surface immediately south of the existing facility. The MCR is part of the closed-cycle 

cooling system for STP Units 1 and 2 and acts as the normal heat sink for waste heat generated 

during operations of these units. The MCR is currently operated to dissipate waste heat from 

the operations of existing Units 1 and 2, primarily via evaporation and radiation to the 

atmosphere. 
Affected Environment 

NUREG-1937 2-18 February 2011 

Figure 2-11. The Six LCRA Dams and the Corresponding Highland Lakes They Impound 

Water is lost from the MCR due to evaporation and seepage. A network of relief wells exists 

along the MCR embankment. These relief wells drain some water away from the Shallow 

Aquifer that receives seepage from the MCR and discharges it into site drainage ditches. The 

site drainage ditches discharge to the Little Robbins Slough located towards the west of the 

STP site and to the Colorado River just upstream of the RMPF located towards the east. Water 

loss from the MCR due to evaporation results in a build-up of total dissolved solids (TDS) within 

the reservoir. Make-up water from the Colorado River is withdrawn from the RMPF, which is 

located on the west bank of the river, to maintain the MCR volume and to control the 

concentration of TDS in its waters. The MCR has a buried discharge pipe approximately 1.1 mi 

in length that allows the periodic discharge of water from the reservoir to the Colorado River. 

The outfall of this discharge line is equipped with seven ports located along the west bank of the 

Colorado River approximately 2 miles downstream of the RMPF. The U.S. Army Corps of 
Affected Environment 

February 2011 2-19 NUREG-1937 

Engineers (Corps) has determined that the MCR is not waters of the United States (Corps 

2009a). The Texas Commission on Environmental Quality (TCEQ) has also stated that the 

MCR is not waters of the State (TCEQ 2007). However, the MCR supports active aquatic and 

avian habitats (see Sections 2.4.1 and 2.4.2). The MCR also has a spillway near its southeast 

corner that allows release of excess water from the MCR to the Colorado River during heavy 

precipitation events. The spillway contains gates that can be manually opened to allow for the 

release of water. 

The Colorado River provides makeup water to replace evaporation loss from the MCR due to the 

normal operation of existing STP Units 1 and 2. The water evaporated from the MCR includes 

that due to natural evaporation and due to induced evaporation from the heat load of Units 1 

and 2. Water is pumped into the MCR from the Colorado River. The MCR was also designed to 

discharge periodically into the Colorado River to maintain the water quality below 3000 μS/cm for 

specific conductivity (STPNOC 2010a). The Colorado River is not the heat sink for the existing 

units. 

As stated below in Section 2.9.1, the topography near the STP site is flat and there is no 

significant difference between local and regional climate. Based on climatological data from 

Victoria and Corpus Christi, mean precipitation varies from 2 to 3 in. per month with maximum 

precipitation of approximately 4 to 5 in. per month in May and June and in September and 

October. Snowfall is not uncommon, occurring over half of the winters; however, snowfall is 

generally limited to trace amounts. Annual potential evapotranspiration(a) in Texas varies from 

approximately 53 in. at Port Arthur to over 79 in. at El Paso (Irrigation Technology Center 2009). 

The annual potential evapotranspiration at Victoria is approximately 57 in. with monthly 

variations from 2.3 in. in December to nearly 7 in. in July (Irrigation Technology Center 2009). 

The power block area of the existing Units 1 and 2 is drained by gravity to the east via the Plant 

Area Drainage Ditch or via drainage around the Essential Cooling Pond. The Main Drainage 

Channel (MDC) is an unlined channel located north of the power block of the proposed Units 3 

and 4 and runs west before turning southwest after crossing the existing railroad track 

(Figure 2-12). The MDC continues southwest across the west access road and eventually joins 

the Little Robbins Slough west of the MCR. 

Little Robbins Slough is an intermittent stream that originates approximately 2 mi northwest of 

the STP site and has a drainage area of approximately 4 mi2

. During the building of Units 1 and 

2, the original course of the stream was relocated to the west of the MCR. The relocated 

channel runs along the western edge of the MCR embankment, turns east at the southwest 

corner of the MCR embankment and rejoins its natural course approximately 1 mi east of the 

southwest corner of the MCR embankment. The Little Robbins Slough flows into Robbins 

 

(a) Potential evapotranspiration is the evaporation from the soil and transpiration from crops or 

vegetation under unlimited water supply conditions. 
Affected Environment 

NUREG-1937 2-20 February 2011 Figure 2-12. Current and Previous Locations of the Main Drainage Channel (STPNOC 2010d) 
Affected Environment 

February 2011 2-21 NUREG-1937 

Figure 2-13. Kelly Lake and Local Drainages Flowing Into and Out of the Lake 

Slough, which is a brackish marsh that joins the Gulf Intracoastal Waterway (GIWW) 

approximately 4 mi to the south (Figure 2-9). There is no known streamflow or water quality 

monitoring of the Little Robbins Slough. 

The GIWW is a 1300-mi-long man-made canal that runs along the Gulf of Mexico coast from 

Brownsville, Texas, to St. Marks, Florida (TxDOT 2007). The GIWW is connected to the 

Colorado River and the Matagorda Bay. 

Kelly Lake is a small lake located north of the northeast edge of the MCR embankment 

(Figure 2-13). It is fed by a small catchment area north of the lake. The USGS topographical 

map shows at least two drainages that flow into the lake and one that exits the lake. The 

drainage that exits the lake flows generally south along the east side of the MCR embankment 
Affected Environment 

NUREG-1937 2-22 February 2011 

and eventually joins West Branch of the Colorado River near the southeast edge of the MCR 

embankment. 

The RMPF is located on the west bank of the Colorado River approximately 2 mi upstream of 

the MCR discharge outfall. The RMPF currently houses two pumps of 240 cfs capacity and two 

pumps of 60 cfs capacity for a total intake capacity of 600 cfs. The intake structure consists of a 

set of traveling screens, a siltation basin, a sharp-crested weir, and the pumping station. A 

buried pipeline conveys water from the RMPF to the MCR. 

The RMPF contains 24 traveling screens, each 10 ft in width (STPNOC 2010c). The bottom of 

the screens in the embayment is located at an elevation of 10 ft below MSL. Currently, only half 

of the installed traveling screens are used to support the operation of the existing STP Units 1 

and 2. 

2.3.1.2 Groundwater Hydrology 

This section describes the aquifer system at the regional, local, and site-specific scales, and 

summarizes the hydrogeologic properties (including piezometric heads). 

Regional Geology and Aquifer System 

The groundwater aquifers in the region and in the vicinity of the site are described in 

Section 2.3.1.2 of the ER (STPNOC 2010a). The STP site lies in Coastal Prairies sub-province 

of the Gulf Coastal Plains physiographic province. The Coastal Prairies sub-province is a broad 

band paralleling the Texas Gulf Coast (STPNOC 2010a). The sub-province is characterized by 

relatively flat topography ranging from sea level at the coast to 300 ft above MSL along the 

northern and western inland boundaries of the sub-province. Underlying the STP site is a 

wedge of southeasterly dipping sedimentary deposits. Numerous local aquifers are found in the 

thick sequence of alternating and interfingering beds of clay, silt, sand, and gravel. 

Groundwater ranging in quality from fresh to saline is found in these sediments. Three 

depositional environments are evident: continental (alluvial plain), transitional (delta, lagoon, 

beach), and marine (continental shelf). Oscillations of the ancient shoreline have resulted in 

overlapping mixtures of sediments (STPNOC 2010a; Ryder 1996). 

The USGS describes the aquifers underlying the STP site as the Texas coastal lowlands aquifer 

system, and divides the aquifer system into hydrogeologic units or permeable zones A through E 

(Ryder and Ardis 2002). Within the State of Texas, both the Texas Water Development Board 

(TWDB) and the LCRA refer to the aquifer system as both the Gulf Coast Aquifer system and the 

Coastal Lowlands Aquifer System, and they use hydrogeologic unit names rather than letters to 

describe the aquifer system (TWDB 2007, 2006b; Young et al. 2007). Common hydrogeologic 

unit names, from shallow to deep, are as follows (STPNOC 2010a): 
Affected Environment 

February 2011 2-23 NUREG-1937 

• Chicot Aquifer 

• Evangeline Aquifer 

• Burkeville Confining Unit 

• Jasper Aquifer 

• Catahoula Confining Unit 

• Vicksburg-Jackson Confining Unit. 

The naming convention used in Texas, which is different than that used by the USGS, is 

employed in the hydrology sections of this EIS (Figure 2-14). 

In the vicinity of the STP site, the Gulf Coast Aquifer system (i.e., the Coastal Lowlands Aquifer 

system) extends from the coast to approximately 100 mi inland (STPNOC 2010a) (Figure 2-15). 

The Gulf Coast Aquifer thickens from inland toward the Gulf of Mexico. Inland, its base is the 

contact of the aquifer with the top of the Vicksburg-Jackson confining unit. Approaching the 

coast, the base of the aquifer is defined by the approximate depth where groundwater has a 

TDS concentration of more than 10,000 mg/L. The thickness of the aquifer ranges from 0 ft at 

the up-dip limit of the aquifer system in the northwest to approximately 1000 to 2000 ft in 

Matagorda County at the down-dip limit of the system in the southeast (STPNOC 2010a; Ryder 

1996). 

The U.S. Environmental Protection Agency (EPA) has identified the Edwards Aquifer I and 

Edwards Aquifer II as sole source aquifers in Texas (EPA 2009a, b, c). The Edwards Aquifer 

extends west of Austin, Texas. Based on the location of the Edwards Aquifer, the review team 

has determined that neither surface water nor groundwater use would impact the Edwards 

Aquifer. 

Local and Site-Specific Aquifer System 

Within Matagorda County, the Chicot Aquifer is the aquifer used for groundwater production 

(Figure 2-15). In the vicinity of the STP site the aquifer thickness is somewhat greater than 

1000 ft (STPNOC 2010a). Groundwater flow in Matagorda County is generally to the south and 

southeast toward the Gulf of Mexico; however, rivers and creeks incised into the surface 

deposits can alter the direction of groundwater flow locally. Pumping of the aquifer system has 

also resulted in local alterations in groundwater flow direction (STPNOC 2010a; Hammond 

1969). 

In the vicinity of the STP site, the Chicot Aquifer is composed of a Shallow Aquifer and a Deep 

Aquifer, and the Shallow Aquifer is further subdivided into Upper and Lower zones (STPNOC 

2010a). The Shallow Aquifer’s base is between 90 and 150 ft below ground surface (BGS), and 

the Shallow Aquifer is separated from the Deep Aquifer by a zone of predominantly clay 
Affected Environment 

NUREG-1937 2-24 February 2011 

Figure 2-14. Correlation of USGS and Texas Nomenclature (STPNOC 2010a) 

material approximately 150-ft thick. Thus, the upper surface of the Deep Aquifer is between 

250 and 300 ft BGS. The top of the Upper Shallow Aquifer is found approximately 15 to 

30 ft BGS, and its base is at approximately 50 ft BGS. The Lower Shallow Aquifer is found 

between the depths of 50 ft and 150 ft BGS. 

In order of their depth, the Upper Shallow Aquifer exhibits a potentiometric head of 

approximately 5 to 10 ft BGS (STPNOC 2010a). The Lower Shallow Aquifer exhibits a 

potentiometric head of approximately 10 to 15 ft BGS. In 1967, the Deep Aquifer exhibited a 

potentiometric head of approximately 0 ft MSL (STPNOC 2010a; Hammond 1969). However, in 

May 2006, the Deep Aquifer exhibited a potentiometric head of approximately 55 ft below MSL 
Affected Environment 

February 2011 2-25 NUREG-1937 

Figure 2-15. Aquifers of Texas 

beneath the STP site (STPNOC 2010a). This is equivalent to approximately 85 ft BGS where 

the existing ground surface at the locations for the proposed units is 30 ft above MSL (STPNOC 

2010b). The Upper Shallow Aquifer and Lower Shallow Aquifer exhibit semi-confined behavior 

with some movement of groundwater between them. The existing STP Units 1 and 2 reactor 

buildings penetrate the confining strata separating these two aquifers and allow vertical 
Affected Environment 

NUREG-1937 2-26 February 2011 

groundwater movement. The proposed Units 3 and 4 reactor buildings would also penetrate the 

confining strata. Other locations on the STP site also exhibit movement of groundwater 

between the Upper and Lower Shallow Aquifers (e.g., in the vicinity of Kelly Lake and at 

observation well [OW] locations OW-332 and OW-930). The Shallow and Deep aquifers are 

separated by a thicker confining zone. 

Recharge to the Gulf Coast Aquifer occurs in upland areas where strata associated with specific 

aquifers outcrop at the surface and are exposed to infiltration resulting from precipitation or 

irrigation. Aquifers can also be recharged by losing streams and rivers. Outcrop areas are in 

the northern and western portions of the system. Natural discharge from an aquifer occurs 

through springs and seeps, gaining streams, cross-formational flow out of an aquifer, and 

evapotranspiration. In addition, groundwater wells constructed and pumped also result in 

discharge from the aquifer. The Lower Colorado River is described as a gaining stream that 

receives groundwater from aquifers (TWDB 2006b). 

Recharge to aquifers within the Chicot Aquifer underlying the STP site occurs to the northwest 

of the site, and discharge occurs generally to the east, south and southeast of the site 

(STPNOC 2010a). The Shallow Aquifer outcrops at the land surface and is recharged a few 

miles northwest of the STP site in Matagorda County, and it discharges to the Colorado River 

alluvium near the site. The Deep Aquifer outcrops and is recharged farther north and northwest 

in Wharton County and discharges into Matagorda Bay and the Colorado River estuary 

approximately 5 mi southeast of the STP site. 

The mean annual precipitation over Matagorda County ranges from 42 to 46 in. (Ryder and 

Ardis 2002). Based on model simulations, the average recharge in the Texas Gulf Coast 

Aquifer was 0.52 in./yr in 1982 (Ryder and Ardis 2002). During the period from predevelopment 

(the early to mid-1930s) until 1982, there are outcrop areas of the aquifer where irrigation water 

reentered the aquifer by downward percolation. These areas include Matagorda County where 

the change in recharge since predevelopment ranges from less than 0.5 to 2 in./yr (Ryder and 

Ardis 2002). In Wharton County, which is upgradient of Matagorda County, the change in 

recharge since predevelopment is estimated to range from 1 to 6 in./yr. The TWDB in its report 

on aquifers of the Gulf Coast of Texas (TWDB 2006b) stated that during calibration of its model 

the recharge rate was estimated as four percent of precipitation which corresponds to nearly 

2 in./yr in Matagorda County. In a model produced for the LCRA, Young et al. (2007) described 

recharge to the Shallow Aquifer system as ranging from 1.5 to 3.0 in./yr, and to the Deep 

Aquifer system as ranging from 0.25 to 1.0 in./yr. 

A feature at the STP site that influences the Shallow Aquifer is the MCR, which is an engineered 

cooling pond used to dissipate heat from the existing STP units (STPNOC 2010a). The MCR 

was originally sized for four units similar to existing STP Units 1 and 2, and was created above 

the original site grade by constructing a 12.4-mi-long earth-fill embankment. The MCR was 

originally designed to have a normal maximum operating level of 49 ft above MSL and exhibit 
Affected Environment 

February 2011 2-27 NUREG-1937 

approximately 20 ft of hydraulic head above the original ground surface. The MCR has a 

surface area of 7000 ac, and it is a major feature of the 12,220-ac STP site. The existing STP 

Units 1 and 2 are located north of the northern MCR embankment. 

The bottom of the MCR is unlined and acts as a local recharge source for the Upper Shallow 

Aquifer, and it appears to cause some mounding in the Upper Shallow Aquifer and possibly the 

Lower Shallow Aquifer (STPNOC 2010a, b). Descriptions of the Shallow Aquifer are presented 

in Figures 2.4.13-17 and 2.4.13-17A in the Updated Final Safety Analysis Report (UFSAR) for 

STP Units 1 and 2 (STPNOC 2008i). A series of 770 relief wells surround the MCR 

embankment and is designed to collect and discharge some of the seepage from the MCR and 

relieve hydrostatic pressure on the outer slope and toe of the embankment (STPNOC 2010a). 

The UFSAR (STPNOC 2008i) for STP Units 1 and 2 estimated that 68 percent of the seepage 

from the MCR would be captured by the relief well system for an MCR maximum pool elevation 

of 49 ft above MSL. Subsequent to publication of the draft EIS, simulations conducted by the 

applicant have shown approximately 50 percent capture by the relief wells and sand drains 

(STPNOC 2010c). Seepage not intercepted by the relief wells remains in the Upper Shallow 

Aquifer. Potentiometric data on the Upper Shallow Aquifer obtained from observation wells 

completed in 2006 through 2008 reveal that groundwater flow from north-northwest of the STP 

site moves south-southeast toward the Units 3 and 4 power block (STPNOC 2010a, b). This 

groundwater flow from the north-northwest converges with the flow outward from the MCR, and 

the flow within the Upper Shallow Aquifer is then diverted to the southeast and southwest 

around the MCR. 

Initial site characterization efforts completed in 2006 and 2007 were inconclusive with regard to 

mounding in the Lower Shallow Aquifer caused by the MCR. However, additional wells were 

installed in 2008, and quarterly monitoring completed in 2008 yielded more comprehensive 

potentiometric surfaces that show no obvious effect to the Lower Shallow Aquifer from MCR 

seepage into the Upper Shallow Aquifer (STPNOC 2009a, b). 

To the east-southeast of the STP site the Upper Shallow Aquifer discharges to either the 

unnamed tributary flowing into Kelly Lake, groundwater wells, Kelly Lake, or the Colorado River 

(STPNOC 2010a). It is also plausible that groundwater flow to the southwest in the Upper 

Shallow Aquifer could discharge to groundwater wells (STPNOC 2010a). 

In the vicinity of the existing STP units, where the confining unit has been removed, the 

hydraulic gradient between Upper and Lower Shallow aquifers is downward, and groundwater 

movement is interpreted to occur between them (STPNOC 2010a). This interpretation is 

supported by field measurements of water table elevation taken on May 1, 2006 (STPNOC 

2010c) and tritium concentration measurements from 2005 through 2009 (STPNOC 2009a). 

Potentiometric measurements completed in September 2008 (STPNOC 2010b) in the vicinity of 

Kelly Lake indicate an upward groundwater gradient between Lower and Upper Shallow 

aquifers, and suggest groundwater from the Shallow Aquifer discharges to Kelly Lake (STPNOC 
Affected Environment 

NUREG-1937 2-28 February 2011 

2010a). However, measurements completed since September 2008 indicate a downward 

gradient and suggest seasonal variation (STPNOC 2010a). Other plausible groundwater 

discharge locations in the Lower Shallow Aquifer to the southeast include groundwater wells 

and the Colorado River. 

The regional groundwater flow in the Lower Shallow Aquifer approaches the STP site from the 

north-northwest, and, based on recent site characterization data (STPNOC 2010a, b), it would 

be diverted to the southeast. STPNOC (2010b) states that the hydraulic conductivity of the 

Lower Shallow Aquifer southwest of proposed Unit 4 is an order of magnitude lower than the 

region to the southeast, and the potentiometric measurement to the southwest indicate a very 

small and seasonally variable hydraulic gradient. Accordingly, STPNOC does not consider a 

southwest directed pathway in the Lower Shallow Aquifer to be a preferential pathway from 

proposed Unit 4. Thus, in addition to exposure locations to the southeast, there is a plausible 

exposure via groundwater wells to the southwest of proposed Unit 4 from the Upper Shallow 

Aquifer but not the Lower Shallow Aquifer. 

Groundwater flow in the Deep Aquifer is from the northwest (e.g., Wharton County), toward the 

southeast and the Gulf of Mexico. Groundwater production wells located at the STP site 

withdraw an average 798 gallons per minute (gpm) for STP 1 and 2 operations (STPNOC 

2010a). 

The Deep Aquifer potentiometric surface in the vicinity of Units 1 and 2 in 1967 was estimated 

to be near 0 ft MSL (STPNOC 2010a; Hammond 1969). The surface was approximately 

60 ft BGS in 1975 (approximately 37 ft below MSL; local elevation 23 ft above MSL) (NRC 1975; 

STPNOC 2008i). In 1986, prior to operation of existing Units 1 and 2, hydraulic head was 

approximately 75 ft BGS, or approximately 48 ft below MSL where Units 1 and 2 site grade was 

27 ft above MSL (STPNOC 2008i). The potentiometric surface in 2006 following more than 20 

years of Units 1 and 2 operation and associated groundwater withdrawal was approximately 55 

ft below MSL (STPNOC 2010a). Thus, there has been a steady decline in the potentiometric 

surface from 1967 to present. Groundwater reversal is occurring locally to the STP production 

wells with groundwater being drawn to the wells in a radial pattern from the surrounding aquifer. 

Based on the potentiometric surfaces of the Lower Shallow Aquifer (i.e., 10 to 20 ft above MSL 

(STPNOC 2010a, b) and the Deep Aquifer (i.e., 45 to 55 ft below MSL (STPNOC 2010a), there 

is a downward hydraulic gradient. However, there is between 100 and 150 ft of a low hydraulic 

conductivity, predominantly clay, confining zone separating these two aquifers (STPNOC 2008i; 

STPNOC 2010a). The UFSAR for existing Units 1 and 2 (STPNOC 2008i) reports historic 

piezometric levels of the Deep Aquifer, and STP water withdrawals have shown a consistent 

pattern of managed drawdown in the vicinity of production wells with a resulting water table 

elevation of 50 to 55 ft below MSL since 1986. 
Affected Environment 

February 2011 2-29 NUREG-1937 

Hydrogeologic Properties 

The hydrogeologic properties of the groundwater aquifers in the region and in the vicinity of the 

site are described in Section 2.3.1.2.3.6 of the ER (STPNOC 2010a) and Section 2.4S.12 of the 

FSAR (STPNOC 2010b). They are presented here to support later calculation of potential 

impacts on the groundwater resource. Figure 2-16 shows a generalized hydrostratigraphic 

section at the STP site. Table 2-2 and Table 2-3 summarize the hydrogeologic and physical 

data of the strata underlying the STP site. Data for the physical properties of bulk density, total 

porosity and effective porosity shown in Table 2-2 and Table 2-3 were taken from ER Table 

2.3.1-17 (STPNOC 2010a) where the number of samples is also reported. Hydraulic properties 

of the aquifers are from a variety of sources and methods. 

Aquifer data from the TWDB for the region (STPNOC 2010a), STP aquifer pumping tests 

(STPNOC 2010b), STP slug tests (STPNOC 2010b), STP laboratory-derived values (STPNOC 

2010a), and existing STP Units 1 and 2 FSAR results were all compiled and reviewed by 

STPNOC in making its site-specific property value selections. The property values (e.g., 

hydraulic conductivity, yield) presented by the applicant have been compared to property values 

presented in various hydrogeology reports issued by the TWDB (Hammond 1969; TWDB 

2006b), the LCRA (Young et al. 2007; LCRA 2007b), and the USGS (Ryder 1996; Ryder and 

Ardis 2002). These literature values for hydraulic properties of the Gulf Coast Aquifer, and 

especially the Chicot Aquifer, are the result of aquifer tests and model calibration at a larger 

scale than the STP site. Accordingly, a broader range is seen in the literature data, and higher 

values for transmissivity are evident because of the deeper aquifer profiles being characterized 

by wells and model cross sections. Values of total porosity and effective porosity determined 

from STP site samples are higher than those presented by Ryder (1996), but within the range 

for sands, silts, and clays. 
Affected Environment 

NUREG-1937 2-30 February 2011 

Figure 2-16. Generalized Hydrostratigraphic Section Underlying the STP Site 

(STPNOC 2010a) 
Affected Environment 

February 2011 2-31 NUREG-1937 

Table 2-2. Representative Hydrogeologic Properties of Confining Layers in the STP 

Hydrogeologic Strata 

Hydrogeologic 

Unit Property Units 

Representative 

Value Range 

Vadose Zone, 

uppermost 

confining layer 

Thickness ft 20 10–30 

Vertical hydraulic conductivity gpd/ft2 0.0036 (gm) 0.051–0.00051 

Bulk (dry) density pcf 101 (am) 96.4–114.9 

Total porosity % 40 (am) 31.8–42.8 

Lower Shallow 

Aquifer 

Confining Layer 

Thickness ft 20 15–25 

Vertical hydraulic gradient - 0.29 0.02–0.294 

Vertical hydraulic conductivity gpd/ft2

 0.0036 (gm) 0.051–0.00051 

Bulk (dry) density pcf 99 (am) 87.3–107.7 

Total porosity % 42 (am) 36.1–47.2 

Deep Aquifer 

Confining Layer 

Thickness ft 100 100–150 

Vertical hydraulic conductivity gpd/ft2

 0.0036 (gm) 0.051–0.00051 

Bulk (dry) density pcf 101 (am) 82.1–111.4 

Total porosity % 41.0 (am) 33.4–51.8 

Source: STPNOC 2010b 

gpd = gallons per day; gm = geometric mean, am = arithmetic mean; pcf = pounds per cubic foot 

For the Upper Shallow Aquifer, the representative hydraulic conductivity value is the greater of 

the geometric means of the values determined by slug tests and by aquifer tests. In this case, 

the aquifer test value of 165 gpd/ft2

 was higher than the slug test value of 107 gpd/ft2. Use of 

the higher value is a conservative approach because it results in shorter travel time estimates. 

For the Lower Shallow Aquifer, the representative hydraulic conductivity value is the higher 

value of the two data sets (i.e., aquifer test, slug test), which is again based on the aquifer test 

data set. In this case the aquifer test value of 543 gpd/ft2

 was higher than the slug test value of 

152 gpd/ft2

. STP site parameters for the Deep Aquifer are within the range shown by others 

(Hammond 1969; Ryder 1996; Young et al. 2007). Use of the STP site-specific data sets and 

representative values are preferred over regionally developed parameters since they are likely 

to better represent site conditions. 

The vertical hydraulic gradient shown in Table 2-2 for the Lower Shallow Aquifer confining strata 

is a downward directed gradient and its value is based on numerous measurements made at 

well pairs in the Upper Shallow Aquifer and the Lower Shallow Aquifer. The basis and data 

supporting this estimate of vertical gradient are provided in the FSAR Rev 4 Table 2.4S.12-8 

(STPNOC 2010b). Estimates of horizontal hydraulic gradient in the Upper and Lower Shallow 

aquifers are also based on field observations of the piezometric surface in each aquifer, 

respectively. To be conservative, hydraulic gradient values from the high end of measured 

ranges are assigned as representative values. 
Affected Environment 

NUREG-1937 2-32 February 2011 

Table 2-3. Representative Hydrogeologic Properties of Aquifers in the STP Hydrogeologic 

Strata 

Hydrogeologic Unit Property Units 

Representative 

Value Range 

Upper Shallow Aquifer; 

piezometric surface 5 to 

10 ft BGS 

Thickness ft 25 20–30 

Transmissivity gpd/ft 3708 (gm) 

6800 (am) 

1100–12,500 

Storage coefficient - 1.20E-03 (am) 1.7E-03–7E-04

Horizontal hydraulic 

conductivity 

gpd/ft2

 165 (gm) 65–420 

Horizontal hydraulic 

gradient 

- 0.002 (southeast) 

0.0008 (southwest) 

0.0007–0.002; 

0.0005–0.0008

Bulk (dry) density pcf 99 (am) 97.2–100.2 

Total porosity % 41 (am) 39.5–41.7 

Effective porosity % 33 (am) 31.6–33.4 

Lower Shallow Aquifer; 

piezometric surface 

10 to 15 ft BGS 

Thickness ft 40 25–50 

Transmissivity gpd/ft 18,209 (gm) 

20,050 (am) 

13,000–33,150

Storage coefficient - 5.8E-4 (am) 4.5E-4–7.1E-4 

Horizontal hydraulic 

conductivity 

gpd/ft2

 543 (gm) 

554 (am) 

410–651 

Hydraulic gradient - 0.0007 (southeast) 0.0004–0.0007

Bulk (dry) density pcf 102 (am) 94.5–120.0 

Total porosity % 39 (am) 28.8–43.9 

Effective porosity % 31 (am) 23.0–35.1 

Deep Aquifer Thickness ft 800–>1000 

Transmissivity gpd/ft 31,379 (gm) 

33,245 (am) 

24,201–50,000

Storage coefficient - 4.9E-4 (am) 2.2E-4–7.6E-4 

Horizontal hydraulic 

conductivity 

gpd/ft2

 420 (gm) 103–3950 

Hydraulic gradient - Directed toward STP 

wells 

Bulk (dry) density pcf 103.1 NA 

Total porosity % 38.8 NA 

Effective porosity % 31.0 NA 

Sources: STPNOC 2010b; Ryder 1996; LCRA 2007b 

gpd = gallons per day; gm = geometric mean, am = arithmetic mean; pcf = pounds per cubic foot.
Affected Environment 

February 2011 2-33 NUREG-1937 

Groundwater Pathways 

If spills were to occur at the STP site and were to reach saturated groundwater, the most likely 

aquifers to be affected would be the Upper and Lower Shallow aquifers. Seepage from the 

MCR would recharge the Upper Shallow Aquifer. 

2.3.2 Water Use 

This section describes the current water use in the Colorado River Basin including that needed 

for operation of existing STP Units 1 and 2. 

In Texas, water use is regulated by the Texas Water Code. As established by Texas Water 

Code, surface water belongs to the State of Texas (Texas Water Code, Chapter 11, 

Section 11.021). The right to use surface waters of the State of Texas can be acquired in 

accordance with the provisions of the Texas Water Code, Chapter 11. In Texas, surface water 

is a commodity. Since the Colorado River Basin is currently heavily appropriated, future water 

users in this basin would likely obtain surface water by purchasing or leasing existing 

appropriations. Regarding groundwater, Texas law has allowed landowners to pump the water 

beneath their property without consideration of impacts to adjacent property owners 

(NRC 2009c). However, Chapter 36 of Texas Water Code authorized groundwater 

conservation districts to help conserve groundwater supplies. Chapter 36, Section 36.002, 

Ownership of Groundwater, states that ownership rights are recognized and that nothing in the 

code shall deprive or divest the landowners of their groundwater ownership rights, except as 

those rights may be limited or altered by rules promulgated by a district. Thus, groundwater 

conservation districts with their local constituency offer groundwater management options 

(NRC 2009c). The existing STP Units 1 and 2 use current STPNOC water rights granted by the 

TCEQ and the conditions of the existing STPNOC-LCRA water contract to withdraw surface 

water from the Colorado River. Groundwater used by STP Units 1 and 2 is withdrawn from the 

Deep Aquifer under STPNOC’s existing Coastal Plains Groundwater Conservation District 

(CPGCD) permit. STPNOC has stated that the proposed Units 3 and 4 would operate within the 

limits of these existing surface water and groundwater appropriations (STPNOC 2010a). 

Following the drought of record during 1950 to 1957, the TWDB was established to plan and 

finance water supply projects. In 1997, Texas Senate Bill 1 created a new water planning 

process that uses sixteen planning regions, called Regional Water Planning Areas (or Regions), 

within the State. The Bill designated TWDB as the lead agency with the responsibility to 

coordinate the regional water planning process and to develop the statewide water plan. The 

most recent Water Plan, the 2007 plan, was adopted on November 14, 2006 (TWDB 2007). 

The STP site is located in the Lower Colorado Regional Water Planning Group (LCRWPG), or 

Region K. The area of Region K follows the Colorado River from mid-state to the Gulf of 

Mexico. 
Affected Environment 

NUREG-1937 2-34 February 2011 

The State of Texas is also divided into a number of River Authorities that were created by the 

State legislature to manage surface water resources in river basins within the State. The STP 

site is located in the LCRA, which was created by the Texas legislature in 1934. 

As of November 2009, the State of Texas had 96 groundwater or underground water 

conservation districts that were created either by the Texas legislature or by TCEQ using a local 

petition process. The conservation districts have the authority to regulate the spacing between 

water wells, the production of water from wells, or both. 

While the River Authorities act as managers and suppliers of surface water and Groundwater 

Conservation Districts act as managers and permitting authorities for groundwater within their 

respective areas, water planning at the regional level is performed by the Regions and the 

TWDB brings the Regional Water Plans together to adopt the State Water Plan. Regional and 

State-level water planning consider demands, supplies, and future development of both surface 

and groundwater resources. 

2.3.2.1 Surface-Water Use 

The existing STP Units 1 and 2 use surface water provided under contract by the LCRA for 

make-up water requirements of the MCR. Of the six highland lakes that are formed by the six 

highland dams that LCRA operates, Lakes Travis and Buchanan provide water supply for 

communities, industries, agriculture, and aquatic life. Water rights are issued by TCEQ for 

stored water or for run-of-the-river water and senior water rights holders have priority over the 

diversions if the water supply is limited during dry years. Water can be directly diverted from the 

Colorado River by run-of-the-river water rights holders (LCRWPG 2006). 

The LCRWPG produced the Region K Water Plan in 2006 (LCRWPG 2006). The LCRWPG 

estimated the surface water supply in Matagorda County to be 184,857 ac-ft/yr in 2010 and 

decreasing to 132,193 ac-ft/yr in 2060. The LCRWPG has proposed water management 

strategies including new water supplies (i.e., surface water and groundwater) and water 

conservation to meet the level of water demand anticipated between 2010 and 2060. Total 

water demand for Matagorda County during this period ranges from 302,570 ac-ft/yr in the 2040 

decade to 286,093 ac-ft/yr in the 2060 decade, and averages 292,038 ac-ft/yr between 2000 

and 2060. The total water demand for Matagorda County includes the STPNOC water rights of 

102,000 ac-ft/yr (LCRWPG 2006). 

In the report “Water for Texas 2007” produced by the TWDB in 2006 (TWDB 2007), the total 

water demand in Region K is projected to increase from 1,078,041 ac-ft/yr in 2010 to 1,302,682 

ac-ft/yr in 2060. During this same period, existing water supplies are projected to decline from 

1,182,078 ac-ft/yr to 887,972 ac-ft/yr. The decline in water supply is attributed to reservoir 

sedimentation and expired water contracts (TWDB 2007). However, TWDB (2007) stated that 
Affected Environment 

February 2011 2-35 NUREG-1937 

water management strategies are estimated to offset this through a combination of 

conservation, reuse, new supplies, and desalination measures. Accordingly, the total water 

demand is expected to be met. 

The current surface water resource of the Colorado River near the STP site, represented by the 

average of mean annual discharges during water years 1949 to 2008 at the Bay City USGS 

streamflow gauge, is 2629 cfs (1,903,000 ac-ft/yr). Some of this flow is reserved for instream 

flow needs. 

STPNOC currently holds a water right for 102,000 ac-ft of water per year from the Colorado 

River and is authorized to divert water up to a maximum rate of 1200 cfs (LCRA-STPNOC 

2006). The diversion is limited to 55 percent of flows in excess of 300 cfs measured at the 

USGS streamflow gauge at Bay City Dam (USGS gauge 08162500). In addition, STPNOC also 

has access to a maximum of 20,000 ac-ft of water per year for operation of existing Units 1 and 

2 on a rolling five-year average basis, of firm water(a) to help maintain the MCR water surface 

elevation at or above 27 ft MSL. During delivery of firm water, diversion of the river flow is 

restricted only by the LCRA estuary requirement. According to its Water Management Plan 

(LCRA 2010), the LCRA releases water into the Lower Colorado River from Lakes Buchanan 

and Travis to meet bay and estuary needs. The LCRA releases the critical bay and estuary 

inflow need of 171,120 ac-ft/yr (236 cfs) every year. In years when the lakes are between 

55 and 86 percent full on January 1, LCRA releases 250,680 ac-ft/yr (346 cfs) and the release 

increases to 1.03 million ac-ft/yr (1423 cfs) if the lakes are more than 86 percent full on 

January 1. 

Using TCEQ’s water rights database (TCEQ 2009a), the review team determined that there are 

29 active water rights holders in the Colorado River Basin between the Mansfield Dam and the 

STP site. The combined withdrawal rights for these holders are 327,376 ac-ft/yr. The average 

annual discharge of the Colorado River, based on streamflow measured during 1899 through 

2009 at the Colorado River at Austin, Texas gauge (USGS gauge 08158000) approximately 

5 mi downstream of Austin, Texas is 2193 cfs (1,587,653 ac-ft/yr). Therefore, the review team 

determined that approximately 21 percent of the surface water resource near Austin, Texas, is 

currently allocated for use between Mansfield Dam and the STP site. 

As reported by TCEQ in April 2009, there are 52 active withdrawals in Matagorda County on the 

Colorado River, various streams, creeks, and sloughs (TCEQ 2009a). The Colorado River 

water rights belonging to the LCRA (4,168,930 ac-ft/yr), the City of Austin (520,403 ac-ft/yr), and 

the Colorado River Municipal Water District (103,000 ac-ft/yr) are greater in quantity than those 

of STPNOC (102,000 ac-ft/yr). In Matagorda County, LCRA is the only entity with water rights 

greater in quantity than STPNOC (TCEQ 2009a). There are several water rights holders with a 

 

(a) Firm water is that which is diverted from storage under a contact or resolution issued by the LCRA to 

high-priority users (Watkins et al. 1999). 
Affected Environment 

NUREG-1937 2-36 February 2011 

priority date earlier than that of STPNOC’s, however, the combined quantity of these water 

rights, excluding those belonging to LCRA, is 28,867 ac-ft/yr. The City of Corpus Christi has 

total water rights amounting to 533,305 ac-ft/yr (TCEQ 2009a), out of which 35,000 ac-ft/yr are 

from the Colorado River. The 35,000 ac-ft/yr water right was acquired by the City in 1999. All 

of the City’s water rights from the Colorado River have a priority date of November 2, 1900 and 

are designated for industrial use according to the TCEQ water rights database (TCEQ 2009a). 

Water lost from the MCR to consumptive use at the STP site is replaced by pumping from the 

Colorado River. Under normal river flow conditions, STPNOC currently diverts water from the 

Colorado River for the existing Units 1 and 2 using the rules stated above. From 2001 to 2006, 

STPNOC diverted an average of 37,084 ac-ft of water per year for operation of Units 1 and 2 

(STPNOC 2010a). The applicant also reported that the existing consumptive water use from 

the Colorado River is approximately 34,821 ac-ft/yr (STPNOC 2010a). The existing 

consumptive use is estimated to be 2 percent (34,821 ac-ft/yr of use compared to 1,903,000 acft/yr of current surface water resource (i.e., streamflow of the Colorado River as measured at the 

Bay City USGS gauge). When compared to the TWDB estimates of water supplies in Region K 

(TWDB 2007), the current STP water use for Units 1 and 2 during normal operations would be 

3 percent in 2010 (34,821 ac-ft/yr of use compared to 1,182,078 ac-ft/yr of estimated supplies). 

Water evaporated from the MCR has two components: (1) natural evaporation that occurs at 

the free water surface without addition of any heat load from the STP units and (2) induced 

evaporation that occurs because of the additional heat loads discharged with the circulating 

water into the MCR. The normal and maximum natural evaporation from the MCR are 

19,912 gpm (32,118 ac-ft/yr) and 23,109 gpm (37,275 ac-ft/yr), respectively (STPNOC 2008i). 

The normal and maximum induced evaporations from STP Units 1 and 2 heat loads were 

reported by the applicant to be 33,200 and 37,200 ac-ft/yr, respectively (STPNOC 2009b). The 

normal and maximum conditions refer to 93 and 100 percent load factors, respectively 

(STPNOC 2009b). 

2.3.2.2 Groundwater Use 

Groundwater use from the Gulf Coast Aquifer system increased between 1940 and the mid1980s. One cause was the increase in rice irrigation, and Matagorda County was among the 

counties where this occurred. The largest pumpage from the aquifer was reported in the 

Houston area where notable subsidence and substantial increases in pumping lift occurred. 

Issues with overpumping the groundwater resource included land subsidence, saltwater 

intrusion, stream base-flow depletion, and increased pumping lift. Groundwater use from the 

Gulf Coast Aquifer system has declined because of these issues and in the mid-1980s the 

TWDB forecast a decline in groundwater use in the Gulf Coast Aquifer through 2030. 

Matagorda County was projected to see a net decrease of 48 percent with pumping decreasing 

from 21,528 gpm (31 MGD) in 1985 to 11,111 gpm (16 MGD) in 2030 (Ryder and Ardis 2002). 
Affected Environment 

February 2011 2-37 NUREG-1937 

Under Texas State law (Water Code, Title 2, Subtitle E, Chapter 36) groundwater conservation 

districts have the authority and responsibility to define the managed available groundwater in 

the district (Sec 36.1071 (e)(3)(A)), and the amount of groundwater being used in the district 

(Sec 36.1071 (e)(3)(B)), and to issue permits based on the managed available groundwater 

resource. The CPGCD, which is responsible for the groundwater underlying Matagorda County, 

Texas, has adopted a groundwater availability value of 30,520 gpm (49,221 ac-ft/yr) (Turner 

Collie & Braden Inc. 2004). This value is consistent with the groundwater availability value 

appearing in the regional water plans produced in 2002 and 2006 for the TWDB by the Lower 

Colorado Regional Water Planning Group (Turner Collie & Braden Inc. 2004; LCRWPG 2006). 

The 49,221 ac-ft/yr value is based on an estimate of maximum usage in 2050 (LCRWPG 2006). 

Groundwater management by the CPGCD is an ongoing process. While the current managed 

available groundwater(a) value is 30,520 gpm (49,221 ac-ft/yr), under Texas State law the district 

is engaged in a process of defining and adopting the desired future condition(b) and an updated 

managed available groundwater value. The district expects to update the “managed available 

groundwater” value after receipt of information from the TWDB, which is responsible for 

simulating the groundwater resource using a groundwater availability model (CPGCD 2009a). 

An estimate of groundwater supplies representative of the ability of water supply systems to 

provide groundwater is provided in Table 4 of the CPGCD Management Plan (Turner Collie & 

Braden Inc. 2004). The estimated groundwater supply level is a constant 22,189 gpm 

(35,785 ac-ft/yr) through 2050. A similar value appears in Table 3.30 of the LCRWPG report 

(LCRWPG 2006); it ranges from 22,225 to 22,221 gpm (35,844 to 35,838 ac-ft/yr) over the 

period 2000 through 2060. 

The CPGCD provides a summary of the history of groundwater withdrawal from the Gulf Coast 

Aquifer in the district. Table 2 (Turner Collie & Braden 2004) of the management plan on 

groundwater use presents available data from 1980 through 2000. Groundwater pumpage 

peaked in Matagorda County in 1988 at 27,055 gpm (43,634 ac-ft/yr), and has declined since 

but not continuously. A low pumpage rate of 8783 gpm (14,165 ac-ft/yr) occurred in 1998. The 

CPGCD reports an average total groundwater usage rate of 18,746 gpm (30,233 ac-ft/yr) 

through the year 2000. 

 

(a) “Managed available groundwater” means the amount of water that may be permitted by a 

groundwater conservation district for beneficial use in accordance with the desired future condition of 

the aquifer as determined under Section 36.108 of Texas water code, i.e., consideration given to the 

joint planning of multiple districts within a groundwater management area. 

(b) “Desired future condition” is one or more metric that specifies the future value of the related aquifer 

characteristic such as groundwater elevation, groundwater quality, spring flow, land subsidence and 

other aquifer characteristics that may be deemed suitable by a groundwater conservation district and 

groundwater management area. 
Affected Environment 

NUREG-1937 2-38 February 2011 

Strategies by the LCRWPG and the CPGCD to provide for the future demand are divided into 

surface water and groundwater strategies (LCRWPG 2006; Turner Collie & Braden 2004). 

These strategies provide a decadal estimate of groundwater specific management that would 

augment the 22,189 gpm (35,785 ac-ft/yr) existing groundwater supply in Matagorda County. 

These two projections of supplemental groundwater resource availability from the Region K 

Water Plans issued in 2002 and 2006 were 14,049 gpm (22,658 ac-ft/yr) through the year 2050 

and 18,320 gpm (29,546 ac-ft/yr) through the year 2060, respectively. Thus, based on the more 

recent 2006 Water Plan, the projected use of groundwater through 2060 is approximately 

40,509 gpm (65,331 ac-ft/yr). However, the strategies to augment existing groundwater 

supplies require financial resources to build infrastructure before the total projected groundwater 

resource would be available in 2060. 

In addition to the above groundwater resource estimates, there is the total permitted amount of 

groundwater within the CPGCD. The three-year permitted total for the period 2005 through 

2007 was 259,840 ac-ft. For the period 2008 through 2010 the permitted total is down to 

153,854 ac-ft (CPGCD 2009b). This reduction in total permitted amount was a result of efforts 

by the CPGCD to convince owners of groundwater use permits to request groundwater 

quantities consistent with their realistic needs. The CPGCD estimates that the annual permitted 

amount for each of these three-year permit periods is 86,600 ac-ft/yr and 51,285 ac-ft/yr 

(CPGCD 2009b). 

The quantity of groundwater permitted and the various groundwater resource estimates 

described above are summarized below in Table 2-4. The annual quantity of groundwater 

permitted by the CPGCD exceeds the current estimates of managed available groundwater and 

the estimated groundwater supply. It also exceeds recorded usage within the county. The 

infrastructure is in place at the STP site to fully utilize its permit limit (described below), and, 

therefore, while it has not been fully used to date, the full permit limit is included in the estimated 

groundwater supply value of 22,189 gpm (35,785 ac-ft/yr). The full STP permit limit is also 

included in the annual permitted value of 31,800 gpm (51,285 ac-ft/yr). It is apparent from the 

CPGCD data (see Table 2-4) that the existing groundwater supply infrastructure (e.g., 

groundwater wells and supply infrastructure) does not yet exceed the managed available 

groundwater resource, despite the fact that the CPGCD may have over-allocated the 

groundwater resource in aquifers underlying Matagorda County (i.e., “managed available 

groundwater” is less than “annual permitted (2008-2010)” in Table 2-4) (TC&B 2004, CPGCD 

2009b). In addition, the CPGCD is involved in the review and approval process for development 

of the groundwater supply infrastructure, (e.g., the review and approval of well drilling and 

groundwater transportation permits). 

Aside from the STP production wells which are located on the STP site, there are three public 

water supply wells approximately 3.75 mi (6 km) southeast of the site (STPNOC 2010a). They 

serve the Exotic Isle Subdivision, the Selkirk water system, and the Selkirk Island Utilities, and 
Affected Environment 

February 2011 2-39 NUREG-1937 

all are completed in the Deep Aquifer. The closest non-public water supply wells are two wells 

located approximately 1.25 mi northeast of the site. They are livestock water supply wells. 

Table 2-4. Groundwater Resource Estimates for Matagorda County 

Resource Description gpm ac-ft/yr References 

Managed Available Groundwater 30,520 49,221 TC&B 2004, Table 1 

Estimated Groundwater Supply 22,189 35,785 TC&B 2004, Table 4 

Average GW Use 1980-2000 18,746 30,233 TC&B 2004, Table 2 

High Groundwater Use – 1988 27,055 43,634 TC&B 2004, Table 2 

Low Groundwater Use – 1998 8783 14,165 TC&B 2004, Table 2 

Future Demand – total in – 2060 40,509 65,331 LCRWPG 2006 

Annual Permitted (2008 – 2010) 31,800 51,285 CPGCD 2009b 

Current usage by STP for existing Units 1 and 2 was estimated as an average value of 683 gpm 

(1101 ac-ft/yr) between 1980 and 2000 (Turner Collie & Braden 2004). However, using more 

recent values from 2001 through 2006, average groundwater use is estimated at 798 gpm 

(1287 ac-ft/yr) (STPNOC 2010a). The permitted limit of groundwater usage by STP is 

approximately 1860 gpm (3000 ac-ft/yr) or an absolute usage of 2.93E+09 gallons (9000 ac-ft) 

during the approximately 3-year permit period(a) (CPGCD 2008). STP has five groundwater 

production wells completed in the Deep Aquifer that are used to supply groundwater for the 

operation of STP Units 1 and 2. 

A consideration with regard to groundwater use in the region is subsidence caused by 

substantial declines in groundwater piezometric levels and the consolidation of clays. Recent 

studies by the USGS (Ryder and Ardis 2002; Kasmarek and Robinson 2004) and the LCRA 

(2007a) address subsidence in the Gulf Coast Aquifer region. Ryder and Ardis (2002) 

described the large withdrawal of groundwater in the rice-irrigation region (1900–1975) including 

most of Jackson and Wharton Counties, and portions of others including Matagorda County, as 

causing the compaction of clays and a subsidence of less than 1 ft over most of the region with 

somewhat higher subsidence of 1.5 ft noted in western Matagorda County. However, Ryder 

and Ardis (2002) concluded that the subsidence was fairly evenly distributed in this mostly rural 

region, and undesirable impacts were minimized. Hammond (1969) also concluded that 

subsidence in Matagorda County was not excessive. Hammond noted that excessive 

subsidence can result in impacts such as cracking highways, breaking pipelines, and sinking of 

building foundations. 

 

(a) For the current groundwater operating permit, the issue date is February 7, 2008, and the expiration 

date is February 28, 2011. For future groundwater permits, the permit term may vary slightly, but 

would be approximately 3 years. 
Affected Environment 

NUREG-1937 2-40 February 2011 

A report completed by the Lower Colorado River Authority and San Antonio Water System 

(LCRA-SAWS) Water Project also estimated land-surface subsidence since 1900 over most of 

Matagorda County to be less than 1 ft (LCRA 2007a). Where land-surface subsidence exceeds 

1 ft in northwest Matagorda County, it is attributed to groundwater withdrawals associated with 

gas/petroleum exploration and sulfur mining. 

The USGS completed a model of groundwater flow and land-surface subsidence applicable to 

the northern part of the Gulf Coast Aquifer system (Kasmarek and Robinson 2004). This 

modeling effort focused on the Harris-Galveston-Fort Bend County area where as much as 10 ft 

of subsidence has occurred; however, the model extended to include Wharton and Matagorda 

counties to the southwest. The model match was close to measured values in the focus area, 

and predicted no subsidence in the coastal irrigation area including Wharton and Matagorda 

counties. 

During construction and through operation in 1993 of STP Units 1 and 2, a subsidence rate of 

less than 0.1 in. to about 0.2 in. per year was observed (STPNOC 2008a). 

2.3.3 Water Quality 

The following sections describe the water quality of surface-water and groundwater resources in 

the vicinity of the STP site. Monitoring programs for thermal and chemical water quality are also 

described. 

2.3.3.1 Surface-Water Quality 

This section describes the water quality of surface water bodies near the STP site that may be 

affected by the construction and operation of proposed Units 3 and 4. STPNOC presented a 

discussion of the water quality conditions in Section 2.3.3.1 of the ER (STPNOC 2010a). 

The State of Texas divides river reaches into segments for water quality determination. The 

segment of the Colorado River adjacent to the STP site, Segment 1401, is classified as a Tidal 

Stream (TCEQ 2008a). The TCEQ lists aquatic life, contact recreation, and fish consumption as 

some of the uses of this segment. The TCEQ, under the Federal Water Pollution Control Act 

(Clean Water Act) Section 305(b), prepares a statewide Water Quality Inventory. The TCEQ 

also identifies impaired water bodies during this process and lists them on the 303(d) List. 

Segment 1401 is listed on the 2008 Texas 303(d) List as impaired by presence of bacteria 

(TCEQ 2008a). 

The MCR is part of the closed-cycle cooling system for the existing units. The MCR is permitted 

to occasionally discharge to the Colorado River through a buried pipeline under a Texas 

Pollutant Discharge Elimination System (TPDES) permit (TCEQ 2005). Since filling of the MCR, 

there has been one test of the MCR discharge system (STPNOC 2010a). The current TPDES 

permit allows an average daily MCR discharge of 144 MGD with a daily maximum of 200 MGD. 
Affected Environment 

February 2011 2-41 NUREG-1937 

The average daily MCR discharge temperature is limited to 95°F with a daily maximum of 97°F. 

Total residual chlorine in the MCR discharge is limited to a daily maximum of 0.05 mg/L. 

The pH of the MCR discharge is limited between 6.0 and 9.0 standard units. The TPDES permit 

specifies that MCR discharge must not exceed 12.5 percent of the flow of the Colorado River at 

the discharge point. The permit also restricts the MCR discharges to periods when the flow of 

the Colorado River adjacent to the site is 800 cfs or greater. The MCR discharge facility 

consists of seven submerged ports located on the west bank of the Colorado River 

approximately 2 mi downstream of the RMPF. Each port can discharge at a maximum rate of 

44 cfs, for a total maximum MCR discharge of 308 cfs. 

The segment of the Colorado River adjacent to the STP site, Segment 1401, is classified by the 

TCEQ as tidal (TCEQ 2009b). The water body uses for the segment include aquatic life use, 

contact recreation use, general use, and fish consumption use. Title 30 of Texas Administrative 

Code (30 TAC), Part 1, Chapter 307, §307.10, Appendix A lists site specific uses and criteria for 

classified segments. The criteria specified for Segment 1401 are a minimum 24-hour mean 

dissolved oxygen at any point within the segment of 4.0 mg/L, a pH range of 6.5 and 

9.0 standard units, an indicator bacteria count of 126 colonies per 100 mL or alternatively, fecal 

coliform criteria of 200 colonies per 100 mL, and a maximum temperature of 95°F at any point 

within the segment. The 2008 Texas 303(d) list (TCEQ 2009c) lists Segment 1401 impaired by 

bacteria since 2006. A total maximum daily load (TMDL) is currently being developed by TCEQ 

for this segment. The other surface water bodies near the STP site, Little Robbins Slough, 

West Branch of the Colorado River, and Kelly Lake are not listed in the 303(d) list. East 

Matagorda Bay and Matagorda Bay are listed since 1996 in the Texas 303(d) list as impaired by 

bacteria. TMDLs are also currently being developed by TCEQ for these waters. 

At the USGS gauge 08162500, Colorado River near Bay City, Texas, monthly water quality 

sampling data exist only for the months October 1974, through October 1976, February and 

June of 2000, and March and June of 2001. The LCRA monitors water-quality data in the 

Colorado River Basin to evaluate overall water quality, ecological conditions, and compliance 

with State water quality standards (LCRA 2009a). 

The LCRA monitors Colorado River water quality at a station named Colorado River Tidal at 

Selkirk Island, located approximately 2 mi downstream from the FM 521 and approximately 

0.7 mi downstream from the RMPF. The water quality data is available for this station from 

LCRA (2009c). 

Water quality data at the Selkirk Island station show a dissolved oxygen range from 0 to 

13.5 mg/L with an average of 6.5 mg/L for the period October 1982 through November 2008. 

For the same period, pH measurements ranged from 6.6 and 9.8 standard units with an average 

of 7.9 standard units and water temperature measurements ranged from 43.5 to 92.1°F (6.4 to 

33.4°C) with an average of 72.5°F (22.5°C). During the period June 1994 through 

September 2001, Escherichia coli bacteria ranged from 1 to 1280 colonies per 100 mL with an 
Affected Environment 

NUREG-1937 2-42 February 2011 

average of 129 colonies per 100 mL. During the period October 1982 through July 2001, fecal 

coliform ranged from 0 to 13,000 colonies per 100 mL with an average of 391 colonies per 

100 mL. The Texas Surface Water Quality Standards (30 TAC Section 307.10, Appendix A) list 

the following criteria for Segment 1401: (1) dissolved oxygen of 4.0 mg/L, (2) pH range of 6.5 to 

9.0 standard units, (3) indicator bacteria count of 35 E. coli for freshwater and Enterococci spp. 

for saltwater per 100 mL or 200 fecal coliform per 100 mL, and (4) water temperature of 95°F. 

Based on this data, the Colorado River near the STP site occasionally does not meet the criteria 

set for dissolved oxygen (12 percent of the times measurements were made) and bacteria 

(24 percent of the times measurements were made). These measurements are consistent with 

the listing of Segment 1401 on the Texas 303(d) List. 

In addition to the water quality monitoring station in the Colorado River, LCRA also maintains 

three stations in the Matagorda Bay. Two of these stations are located in West Matagorda Bay 

and one in East Matagorda Bay. 

2.3.3.2 Groundwater Quality 

This section describes the water quality of groundwater near the STP site that may be affected 

by the building and operation of proposed Units 3 and 4. STPNOC presented a discussion of 

the water quality of groundwater in Section 2.3.3.2 of the ER (STPNOC 2010a). Discussions of 

the present day setting of the underlying groundwater, and of regional salt water intrusion rely 

on the STPNOC ER, STPNOC annual environmental operating reports, and studies performed 

by the USGS and the LCRA. 

Regional water quality data from the mid-1960s show all wells above or just below the EPA 

secondary drinking water standard for TDS (STPNOC 2010a; Hammond 1969). More current 

data for STP production and observation wells indicate that all but a single well are above the 

TDS standard of 500 mg/L (STPNOC 2010a). Locally, groundwater from the Shallow Aquifer is 

described as slightly saline because of TDS concentrations above 1000 mg/L (i.e., slightly 

saline waters have TDS between 1000 and 3000 mg/L). Onsite wells completed in the Shallow 

Aquifer have an average TDS concentration of approximately 1200 mg/L (STPNOC 2010a). 

Several regional wells and a majority of the shallow wells in the more current STP data set also 

exhibited chloride concentrations higher than its EPA secondary drinking water standard value 

of 250 mg/L. Fluoride was higher than the EPA secondary drinking water standard of 2 mg/L in 

a single well in each data set; the regional data set and the STP data set. The site-specific 

data are consistent with the regional water quality information that identify the Deep Aquifer as 

the preferred drinking water source, and identify the Shallow Aquifer as a lower quality water 

source. The water quality signatures of the Upper and Lower Shallow aquifers (i.e., sodium 

chloride and sodium bicarbonate respectively) suggest natural communication is occurring 

between these aquifers in the vicinity of two observation wells; OW-332 (near the northeast 

corner of proposed Unit 3) and OW-930 (approximately 4000 ft east of existing Units 1 and 2). 
Affected Environment 

February 2011 2-43 NUREG-1937 

The MCR is connected hydraulically to the underlying Upper Shallow Aquifer and seepage from 

the MCR recharges the aquifer. A relief well system (i.e., the 770 wells that surround the MCR) 

is designed in part to intercept the majority of the seepage from the MCR into the Upper Shallow 

Aquifer. STPNOC (2010a) has estimated that for the MCR at a maximum pool elevation of 

49 ft above MSL total seepage from the MCR is 3530 gpm (5700 ac-ft/yr), and that 

approximately 68 percent of this or 2390 gpm (3850 ac-ft/yr) is intercepted by the relief wells. 

Recent simulation of the Shallow Aquifer underlying the STP site has indicated that the relief 

wells and sand drains intercept approximately 50 percent of the total seepage from the MCR 

(STPNOC 2010c). Regarding radioactive contaminants in the MCR and in seepage from the 

MCR that recharges the Upper Shallow Aquifer, see Section 5.9.6. 

A potential impact on the quality of the Deep Aquifer groundwater resource in the vicinity of the 

STP site is saltwater intrusion or encroachment resulting from pumping of groundwater in the 

region. Ryder and Ardis (2002) described saltwater intrusion or encroachment as a potential 

threat to the rice-irrigation region that includes Matagorda County because of saltwater-bearing 

deposits downdip, above and below the freshwater deposits. Because of the reduction of 

hydraulic head from long-term pumping of the aquifer system for rice irrigation, saltwater 

encroachment could occur by either lateral migration in coastal areas or vertical migration where 

freshwater sands overlie saline groundwater. However, because the groundwater system 

exhibits a balance between net recharge and total pumping, Ryder and Ardis (2002) conclude 

that “(s)altwater encroachment is not currently a serious threat to the quality of groundwater 

used in the coastal rice-irrigation area” that includes portions of Wharton and Matagorda 

Counties. 

In their study of variable density groundwater flow and groundwater well design, the LCRA 

(2007b) provided a cross sectional analysis of Colorado, Wharton and Matagorda Counties with 

added pumping equivalent to 24,800 gpm (40,000 ac-ft/yr, the historical maximum) in 

Matagorda County over an 80-year period. Wells were placed in the model beginning about 

1 mi from the coast, and screened over 400 to 500 ft to a depth of about 1000 ft BGS. 

Maximum drawdown was about 80 ft over the 80-year period, and the overall water quality did 

not change significantly. The study also evaluated well design parameters. For wells with 400 

to 500 ft screens completed to approximately 700 ft BGS, the LCRA (2007b) study assumed the 

fresh/saline interface occurred at 1200 ft BGS and found for a hydraulic conductivity of 18 ft/day 

and anisotropy ratio of 1000 (Kr/Kv) that the critical pumping rate was 527 gpm. For a more 

realistic anisotropy ratio of 10,000, the LCRA study found that the critical pumping rate was 

14,165 gpm. The LCRA (2007b) study provides guidance to others in the region so that 

groundwater withdrawals should not result in significant degradation of the groundwater quality 

in the regional groundwater system because of saltwater intrusion. 

In the Regional Geology and Aquifer System section, the base of the aquifer is defined as the 

depth where the groundwater has a TDS concentration of more than 10,000 milligrams per liter 

(mg/L). Using this metric, Ryder (1996) noted that the thickness of the aquifer system in 
Affected Environment 

NUREG-1937 2-44 February 2011 

Matagorda County ranged from 1000 to 2000 ft. A measure of impact on the quality of the 

groundwater resource in the Deep Aquifer is the change in depth where the TDS concentration 

is 10,000 mg/L, or the change in depth to thresholds of TDS level associated with higher quality 

water. LCRA (2007b) described the groundwater of the Deep Aquifer according to TDS level as 

either fresh (less than 1000 mg/L), slightly saline (1000 to 3000 mg/L), or moderately saline 

(greater than 3000 mg/L). In the vicinity of the STP site, the LCRA (2007b) study mapped the 

3000 mg/L TDS surface at a depth of between 1000 and 1200 ft BGS. 

2.3.4 Water Monitoring 

2.3.4.1 Surface-Water Monitoring 

The closest USGS streamflow gauge upstream of the STP site is the USGS gauge 08162500, 

Colorado River near Bay City, Texas. Daily discharge in the Colorado River at this gauge is 

available since May 1, 1948. NOAA maintains tide gauges at Freeport and at Port O’Connor. 

Water diverted from the Colorado River to make up the loss of water from the MCR and water 

consumed are monitored monthly and reported to TCEQ annually according to the TCEQ water 

rights permit. The volume of water diverted from the Colorado River is also reported to the 

TWDB annually. 

Monthly water quality data is available for a limited period (see Section 2.3.1.1). Lower 

Colorado River Authority monitors Colorado River water quality at Selkirk Island approximately 

1 mi downstream from the STP intake structure (see Section 2.3.3.1). Data monitored at this 

location includes various flow parameters (such as dissolved oxygen, pH, water temperature, 

and turbidity), bacteria (Escherichia coli, Enterococci spp., and fecal coliform), chemistry 

(biological and chemical oxygen demand, alkalinity, hardness, dissolved calcium and 

magnesium, nitrate, nitrite, phosphorus, sulfate, and total organic carbon), metals in water and 

sediment (including Aluminum, Arsenic, Barium, Cadmium, Chromium, Copper, Lead, Mercury, 

Nickel, Selenium, Silver, and Zinc), and organic material in sediment. 

STPNOC monitors discharges and effluents as required by the TPDES permit for existing STP 

Units 1 and 2 at six locations (Figure 2-17). The effluent flows are compiled as daily totals and 

are reported to TCEQ monthly. When discharge from the MCR to the Colorado River occurs at 

Outfall 001, the rate of discharge is continuously monitored. The other five outfalls are all 

internal to the MCR and are monitored on a daily basis. 

As part of the Radiological Environmental Monitoring Program, STPNOC analyzed water 

samples for radionuclides (including Tritium, Iodine, Cesium, Manganese, Iron, Cobalt, Zinc, 

Zirconium, Niobium, Lanthanum, and Barium) from several locations at the STP site 

(STPNOC 2010a). Only the levels of Tritium were found to be detectable in four of 12 samples. 

The maximum concentration of Tritium was reported in south-southeast part the MCR near the 

discharge facility. 
Affected Environment 

February 2011 2-45 NUREG-1937 

Figure 2-17. Hydrological Monitoring Locations for Existing STP Units 1 and 2 (based on 

STPNOC 2010a, Figure 6.3-1) 
Affected Environment 

NUREG-1937 2-46 February 2011 

Since 1995, STPNOC has also sampled the west branch of the Colorado River, Little Robbins 

Slough, east branch of the Little Robbins Slough, an onsite drainage ditch located northeast of 

the MCR, and the MCR (STPNOC 2010a). Tritium was detected at all six sampled locations 

within these waterbodies. The maximum concentrations found in these waterbodies are 

reported in Table 2-5. The EPA primary drinking water standard for Tritium is 20,000 pCi/L. 

The waters of the MCR are not used for drinking. 

Table 2-5. Maximum Tritium Concentration in Water Bodies Near the STP Site (1995-2005) 

Location 

Maximum Measured Tritium 

Concentration (pCi/L) 

Year the Measurement 

was Made 

West branch of Colorado River 6093 1999 

Little Robbins Slough 7725 1995 

East branch of Little Robbins Slough 6352 1999 

Onsite Drainage Ditch northeast of the MCR 6944 1999 

MCR 17,410 1996 

Source: STPNOC 2010a 

Stormwater runoff discharge from the STP site is monitored at four outfalls (Figure 2-18) during 

precipitation events. One of these outfalls is located on the Colorado River and three on the 

Little Robbins Slough. 

2.3.4.2 Groundwater Monitoring 

Prior to the application for proposed Units 3 and 4, the applicant has conducted annual 

environment surveys including groundwater and published annual reports (STPNOC 2007, 

2008h). The 2006 report presents information generated from sampling 16 Shallow Aquifer 

wells within the existing Units 1 and 2 Protected Area and a comparable number of Shallow 

Aquifer STP controlled wells outside the Protected Area (STPNOC 2007, 2009a). Data from 

wells within the Protected Area are used to monitor past leaks and track contaminant migration 

while data from outside the Protected Area are used to track the migration of water leaving the 

MCR and entering the Shallow Aquifer. During site characterization for STPNOC’s application, 

28 groundwater observation wells were installed in 2006, and an additional 26 observation 

wells were installed in 2008 (STPNOC 2010a). As discussed in Section 2.3.1.2 above, 

hydraulic head in the Upper and Lower Shallow aquifers was reported in the application 

(STPNOC 2010a, b). 
Affected Environment 

February 2011 2-47 NUREG-1937 

Figure 2-18. Stormwater Monitoring Locations for Existing STP Units 1 and 2 (based on 

STPNOC 2010a, Figure 6.3-3) 
Affected Environment 

NUREG-1937 2-48 February 2011 

2.4 Ecology 

This section describes the terrestrial and aquatic ecology of the site and vicinity that might be 

affected by the building, operation, and maintenance of proposed Units 3 and 4 at STP. 

Sections 2.4.1 and 2.4.2 provide general descriptions of terrestrial and aquatic environments on 

and in the vicinity of the STP site and in areas that would be subject to activities required for the 

proposed power transmission system upgrades. These areas include the 20 mi of existing 

transmission line corridor where upgrades would be required, the addition of a new 345-kV 

switchyard on the STP site, and the changes necessary to redirect five existing transmission 

lines into the new switchyard on the STP site (STPNOC 2010a). The 345-kV transmission lines 

to be upgraded originate at the STP site in Matagorda County and travel a 400-ft wide corridor 

for approximately 20 mi, terminating at the Hillje Substation. The Hillje Substation is located in 

the southwestern corner of Wharton County, just across the border from Matagorda County. 

Detailed descriptions are provided where needed to support the analysis of potential 

environmental impacts from building, operating, and maintaining new nuclear power generating 

facilities and along transmission corridors where upgrades and tower replacement would be 

conducted to support the power transmission requirements for Units 3 and 4. These 

descriptions also support the evaluation of mitigation activities identified during the assessment 

to avoid, reduce, minimize, rectify, or compensate for potential impacts. Also included are 

descriptions of monitoring programs for terrestrial and aquatic environments. 

2.4.1 Terrestrial Ecology 

The STP site occupies approximately 12,220 ac immediately west of the Colorado River, 

approximately 10 mi from the river’s confluence with Matagorda Bay, within the Coastal Prairies 

sub-province of the Gulf Coastal Plains physiographic province of Texas (STPNOC 2010a; 

TBEG 1996). This section identifies terrestrial ecological resources and describes species 

composition and other structural and functional attributes of biotic assemblages that could be 

affected by the building, operation, and maintenance of Units 3 and 4 and associated 

transmission lines.

2.4.1.1 Terrestrial Communities of the Site and Vicinity 

The terrestrial communities found in this region are typical of the Coastal Prairies that begin 

near the Gulf of Mexico shoreline (adjoining the Gulf Coast Marshes) and occupy young deltaic 

sands, silts, and clays that form nearly flat grasslands (TBEG 1996). This area is typified by low 

elevation, generally less than 60 ft above MSL, with open prairie habitat interspersed with creek 

and river drainages flowing toward the Gulf Coast marshes. Trees are usually not found except 

locally along streams and in oak groves. Remnants of Coastal Prairies in Texas are dominated 

by little bluestem (Schizachyrium scoparium), brown-seed paspalum (Paspalum plicatulum), 

and Indiangrass (Sorghastrum nutans) (Diamond and Smeins 1984). Bottomland hardwood 
Affected Environment 

February 2011 2-49 NUREG-1937 

forests occur along the major river systems that drain the Coastal Prairies. The Gulf Coast 

Prairies are well suited to agriculture and farming, cattle ranching, and urban and industrial 

development (FWS and USGS 1999). These land uses have transformed the region and much 

of Matagorda County has been converted to croplands or pasture (STPNOC 2010a). Little of 

the original coastal prairie vegetation remains in the region. 

The dominant land cover in the vicinity of the STP site consists primarily of habitats associated 

with agriculture and grazing, and grazing continues on portions of the STP site. Past 

agricultural land uses at the site have influenced the current vegetation at STP. The existing 

plant associations on the STP site consist primarily of successional vegetation occurring on old 

abandoned agricultural fields and pastures. Although the topography of the region is relatively 

flat and low, the landscape at the site can be characterized as either forested and bottomland 

habitats in low lying areas that consist of pastures or patchy forested lands near the Colorado 

River, low-lying wetland habitats, and upland areas where scrub-shrublands and grasslands 

have established on previously cultivated, grazed, or disturbed lands (STPNOC 2010a). Recent 

ecological surveys of the site provided information identifying and describing different habitats 

and mapped the vegetation cover and land use on the STP site (Figure 2-19) (ENSR 2008a; 

STPNOC 2008b). Two open water areas—the approximately 7000-ac MCR and the 46-ac 

ECP—represent the majority of the mapped habitat found onsite (Table 2-6, Figure 2-19). 

Areas immediately adjacent to existing facilities consist of parking areas, gravel lots, and 

landscaped areas. Two other types of land use are identified on the vegetation cover/land-use 

map: a dredge materials disposal area and the spoils area used for the building of existing STP 

Units 1 and 2. The vegetation cover types are briefly described in the following text. 

Forested Communities 

The bottomland forests occur along the site boundary with the Colorado River and represent the 

most diverse habitat found on the STP site. Much of the bottomland area was historically 

modified through land-use practices (clearing and herbicide applications) to promote livestock 

forage production. These bottomlands now consist of a mosaic of forested and pasture lands. 

Dominant tree species include pecan (Carya illinoinensis), sugarberry (Celtis laevigata), live oak 

(Quercus virginiana) and American elm (Ulmus americana). Shrubs and herbaceous plants 

include yaupon (Ilex vomitoria), American beautyberry (Callicarpa americana), dewberry 

(Rubus spp.), sedges (Carex spp.), and poison ivy (Toxicodendron radicans) (STPNOC 2010a). 

Depressions and sloughs within these bottomlands receive drainage from the upland portions of 

the site and provide shallow wetland habitats. Several STP facilities occur within the 

bottomland forest areas, including the RMPF, the dredge materials disposal area, and the MCR 

spillway/blowdown area (ENSR 2008a). 
Affected Environment 

NUREG-1937 2-50 February 2011 

Figure 2-19. Vegetation Cover and Land-Use Cover Types at the STP Site
Affected Environment 

February 2011 2-51 NUREG-1937 

Table 2-6. Approximate Acreages of Habitats and Land Use Found on the STP Site 

Habitat Acreage Habitat Acreage 

Bottomland Forest 1176 Dredge Materials Disposal Area 133 

Upland Forest 53 Construction Spoil Area for Units 1 and 2 41 

Mixed Forest/Grassland 91 Maintained Areas (Mowed Grasses and Forbs) 468 

Pasture/Agriculture 536 Existing Facilities 300 

Scrub Shrub 970 Existing roadways and levees 759 

Mixed Grassland 485 Wetlands including Kelly Lake 162 

Main Cooling Reservoir 7000 Essential Cooling Pond 46 

Sources: ENSR 2008a, STPNOC 2008g 

Upland forested habitat (53 ac) is found adjacent to Kelly Lake (ENSR 2008a) consisting of live 

oak, sugarberry, and yaupon. Immediately east of this community, a 91-ac mixed forest/ 

grassland habitat is leased for cattle. It contains sugarberry and a few live oaks with an 

herbaceous layer consisting of broadleaf carpetgrass (Axonopus compressus), Bermuda grass 

(Cynodon dactylon), and Paspalum species. Additional forested communities are located on 

the east side of the property north of the existing heavy haul road and on the southeast section 

of the property between the MCR spillway and the Colorado River. 

Wetland Communities 

Three types of wetlands are found on the STP site. The largest is a managed 110-ac shallow 

wetland area (part of the Texas Prairie Wetlands Project) that was developed in 1996 in the 

northern portion of the site adjacent to road FM 521 (STPNOC 2010a). To enhance the 

property for waterbirds (STPNOC 2010a), impoundments were built to create foraging habitat 

for wintering waterfowl, wading birds, and shorebirds. This managed wetland area is included 

as part of the Great Texas Coastal Birding Trail that spans the entire Texas Gulf 

(STPNOC 2010a; TPWD 2009g). 

The second significant wetland habitat is associated with the 34-ac Kelly Lake in the eastern 

portion of the site (STPNOC 2010a; ENSR 2008a). It consists of open water areas surrounded 

by emergent vegetation including a band of cattail (Typha spp.) and arrowhead (Sagittaria spp.). 

The third wetland component observed on the STP site includes 29 smaller wetlands totaling 

about 18 ac (Corps 2009b). Nineteen of these are less than 0.50 ac in size while the remaining 

eight range from 0.5 to 5.2 ac in size. The dominant vegetation within these sites includes 

cattail, spikerush (Eleocharis spp.), disk water hyssop (Bacopa rotundifolia), bluestem 

(Andropogon spp.), sea myrtle (Baccharis halimifolia), and rattlebox (Sesbania drummondii). 

Wetland vegetation is also associated with streams modified for surface and stormwater 
Affected Environment 

NUREG-1937 2-52 February 2011 

drainage common throughout the site (ENSR 2007a), including Little Robbins Slough, a stream 

that was relocated when building the MCR for existing Units 1 and 2. 

Upland Communities 

Upland areas on the STP site consist of a patchy mosaic of shrub-dominated and herbaceous 

vegetation typical of successional areas recovering from prior disturbance. Scrub-shrub habitat 

dominates the northern and western portions of the site (ENSR 2008a). This land was 

agricultural land before Units 1 and 2 were built (NRC 1975). The habitat is dominated by sea 

myrtle, dewberry, and patchy grasses—all plants common to disturbed or abandoned 

agricultural land in this region (STPNOC 2010a). Sea myrtle appears to be the most common 

shrub in the plant associations near the proposed plant site (STPNOC 2010a). 

Mixed grasslands occur along the southern site boundary, north and east of the ECP, and 

between the MCR and bottomland habitats. The dominant grass species include angleton 

bluestem (Dichanthium aristatum), King Ranch bluestem (Bothriochloa ischaemum), bristle 

grass (Setaria spp.), brownseed paspalum, and Bermuda grass. Maintained and disturbed 

habitats on the STP site consist of areas that are routinely mowed, such as the outside slopes 

of levees (ENSR 2008a) and mowed fields adjacent to existing reactor facilities. Common 

plants in these areas include dallisgrass (P. dilatatum), brownseed paspalum, angleton 

bluestem, sedge (Carex spp.), Bermuda grass, clover (Trifolium spp.), and carpetgrass 

(STPNOC 2010a). 

Wildlife Species on the STP Site 

Wildlife species found within the STP site are typical of those found in the east Texas coastal 

prairie lands. Common mammals may include white-tailed deer (Odocoileus virginianus), 

bobcat (Lynx rufus), gray fox (Urocyon cinereoargenteus), eastern cottontail rabbit 

(Sylvilagus floridanus), raccoon (Procyon lotor), nine-banded armadillo (Dasypus novemcinctus 

mexicanus), Virginia opossum (Didelphis virginiana), hispid cotton rat (Sigmodon hispidus), and 

feral pig (Sus scrofa). Mammals that were observed on the STP site during recent ecological 

surveys include white-tailed deer, feral pigs, eastern cottontail, swamp rabbit 

(Sylvilagus aquaticus), fox squirrels (Sciurus niger), gray squirrels (S. carolinensis), and hispid 

cotton rat. Of these, white-tailed deer were most often observed (ENSR 2008a). 

Seven bat species occur in Matagorda County, and could potentially be associated with STP. 

These are the eastern pipistrelle or tri-colored bat (Perimyotis subflavus), the eastern red bat 

(Lasiurus borealis), the hoary bat (L. cinereus), the northern yellow bat (L. intermedius), the 

Seminole bat (L. seminolus), the evening bat (Nycticeius humeralis), and the Brazilian or 

Mexican free-tailed bat (Tadarida brasiliensis). 
Affected Environment 

February 2011 2-53 NUREG-1937 

Common reptile species may include the alligator (Alligator mississippiensis), the copperhead 

snake (Agkistrodon contortrix contortrix), the cottonmouth snake (A. piscivorus), the eastern 

hog-nosed snake (Heterodon platirhinos), eastern racer (Coluber constrictor), corn snake 

(Elaphe guttata), eastern rat snake (E. obsoleta), the diamondback watersnake

(Nerodia rhombifer rhombifer), eastern box turtle (Terrapene carolina), ornate box turtle 

(T. ornata), snapping turtle (Chelydra serpentina), red-eared pond slider (Trachemys scripta 

elegans), green anole (Anolis carolinensis), and five-lined skink (Eumeces fasciatus). Other 

reptiles potentially associated with STP include the western diamondback rattlesnake 

(Crotalus atrox), diamondback terrapin (Malaclemys terrapin), and the fence lizard

(Sceloporus undulatus) (ENSR 2007b; STPNOC 2010a). 

Amphibians likely to occur in wetland areas of the STP site include the southern leopard frog 

(Rana sphenocephala), the green tree frog (R. clamitans), and the bullfrog (R. catesveiana)

(ENSR 2007b). Table 2-7 is a list of amphibians known to occur in Matagorda County. 

Table 2-7. Amphibians Found in Matagorda County, Texas

Common Name Scientific Name 

Smallmouth Salamander Ambystoma texanum 

Eastern Newt Notophthalmus viridescens 

Eastern Lesser Siren Siren intermedia 

Gulf Coast Toad Incilius valliceps 

Woodhouse’s Toad Bufo woodhousii 

Northern Cricket Frog Acris crepitans 

Cope’s Gray Treefrog Hyla chrysoscelis 

Green Treefrog Hyla cinerea 

Squirrel Treefrog Hyla squirella 

Gray Treefrog Hyla versicolor 

Spotted Chorus Frog Pseudacris clarkii 

Bullfrog Rana catesbeiana 

Southern Leopard Frog Rana sphenocephala 

Source: AmphibiaWeb 2009

The site and the surrounding region host a large number of resident and migratory birds 

throughout the year. The STP site lies near the terminus of the Central Flyway migration route 

and the managed prairie wetlands are a stop along the Great Texas Coastal Birding Trail 

(TPWD 2009g). The STP site lies within a major migratory corridor for neotropical migrants, 

and radar studies indicate that floodplain forests and other forested wetlands are important 

stopover habitats (STPNOC 2010a).
Affected Environment 

NUREG-1937 2-54 February 2011 

Resident birds commonly seen and observed during recent surveys at the STP site include 

turkey vultures (Cathartes aura), black vultures (Coragyps atratus), crows (Corvus spp.), 

grackles (Quiscalus spp.), northern cardinal (Cardinalis cardinalis), red-winged blackbirds 

(Agelaius phoeniceus), bobwhite quail (Colinus virginianus), and mourning doves 

(Zenaida macroura). Many different species of wading birds were observed at the STP site 

when building Units 1 and 2 including wood storks (Mycteria americana), roseate spoonbills 

(Platalea ajaja), great blue herons (Ardea herodias), great egrets (Ardea alba), white-faced ibis 

(Plegadis chihi), white ibis (Eudocimus albus), and little blue herons (Egretta caerulea) 

(NRC 1975). All of these birds except wood storks have been observed on the site more 

recently during the Mad Island Christmas Bird Count (CBC) surveys conducted each year 

(ENSR 2008a; STPNOC 2008b). Other waterbirds noted onsite included white pelicans 

(Pelecanus erythrorhynchos), laughing gulls (Leucophaeus atricilla), cormorants (Phalacrocorax 

spp.), anhingas (Anhinga anhinga), and belted kingfishers (Megaceryle alcyon). Waterfowl 

species that use STP wetlands include American coots (Fulica americana), teal (Anas spp.), 

and northern shovellers (Anas clypeata) (NRC 1975). Waterfowl observed on the MCR in 1987 

included 16 duck species and 3 species of geese (STPNOC 2010a). Winter CBC surveys found 

23 species of ducks and 5 species of geese (ENSR 2008a). 

Avian species observed during more recent biological surveys on the site (2006 and 2007) are 

indicated in Table 2-8. Within the STP site, 215 total avian species have been documented 

during annual CBCs from 1993 through 2007 (ENSR 2008a). During this 15-year period, an 

average of 122 bird species was observed onsite per year, with a range of 60 to 142 species 

per year. Bird/habitat associations for STP included woodland (101 bird species observed), 

shoreline (48 species), open-water (40 species), grassland (24 species), and scrub-shrub 

(2 species). These species were classified by their habitat of occurrence (where they were 

observed); however, these birds may frequent multiple habitats found on the STP site (ENSR 

2008a; STPNOC 2010a). 

Waterbirds nest on terminal ends of the “Y” dike used to direct water flow in the MCR. Nesting 

on the MCR dikes was first observed in 1986 and has been monitored annually since 2000 as 

part of the Texas Colonial Waterbird Surveys (FWS 2009b). The STP colony has been 

dominated by nesting laughing gulls (53 percent) and gull-billed terns (Gelochelidon nilotica) 

(31 percent) of the approximately 1200 to 1600 nests per year counted from 2000 to 2005 

(STPNOC 2010a). Seven additional bird species nest on the dikes with typically fewer than 

100 nests each. 
Affected Environment 

February 2011 2-55 NUREG-1937 

Table 2-8. Birds Observed On or Around the STP Project Area for Units 3 and 4 

Common Name Scientific Name Habitat Observed 

TransGulf 

Migrant(a)

Red-winged blackbird Agaelaius phoeniceus Grassland/Scrub-shrub 

Anhinga Anhinga anhinga MCR 

Great blue heron Ardea herodias Wetland/MCR 

Cattle egret Bubulcus ibis Grassland/Wetlands 

Red-tailed hawk Buteo jamaicensis Grassland/Scrub-shrub 

Red-shouldered hawk Buteo lineatus Grassland/Scrub-shrub 

Crested caracara Caracara cheriway Grassland 

Turkey vulture Cathartes aura Grassland/Scrub-shrub/Developed 

Belted kingfisher Megaceryle alcyon Wetlands X 

Killdeer Charadrius vociferus Grassland/Developed 

Northern harrier Circus cyaneus Grassland/Scrub-shrub 

Northern bobwhite Colinus virginianus Grassland/Scrub-shrub 

Black vulture Coragyps atratus Grassland/Scrub-shrub/Developed 

American crow Corvus brachyrhynchos Grassland/Scrub-shrub 

Bluejay Cyanocitta cristata Scrub-shrub 

Fulvous whistling-duck Dendrocygna bicolor Wetland 

Little blue heron Egretta caerulea Wetlands 

Snowy egret Egretta thula Wetland/MCR 

Tri-colored heron Egretta tricolor Wetland/MCR 

White ibis Eudocimus albus Grassland/Wetlands 

American coot Fulica americana Wetlands 

Common yellowthroat Geothlypis trichas Scrub-shrub X 

Bald eagle Haliaeetus 

leucocephalus 

River shoreline 

Barn swallow Hirundo rustica Grassland/Developed X 

Laughing gull Leucophaeus atricilla MCR/Developed 

Northern mockingbird Mimus polyglottos Grassland/Scrub-shrub/Developed 

Brown-headed cowbird Molothrus ater Grassland/Scrub-shrub 

Black-crowned night-heron Nycticorax nycticorax Wetland 

Osprey Pandion haliaetus MCR 

American white pelican Pelecanus 

erythrorhynchos 

MCR 
Affected Environment 

NUREG-1937 2-56 February 2011 

Table 2-8. (contd) 

Common Name Scientific Name Habitat Observed

TransGulf 

Migrant(a)

Brown pelican Pelecanus occidentalis MCR 

Cliff swallow Petrochelidon pyrrhonota MCR X 

Roseate spoonbill Platalea ajaja MCR 

Purple martin Progne subis Grassland/Scrub-shrub/Developed X 

Boat-tailed grackle Quiscalus major Grassland/Scrub-shrub/Developed 

Gull-billed tern Gelochelidon nilotica MCR 

Eastern meadowlark Sturnella magna Grassland/Scrub-shrub 

American robin Turdus migratorius Grassland 

Scissor-tailed flycatcher Tyrannus forficatus Grassland/Scrub-shrub X 

Mourning dove Zenaida macroura Grassland/Developed 

Sources: STPNOC 2010a; ENSR 2008a 

(a) Birds that cross the Gulf of Mexico from the Yucatan Peninsula to the Gulf Coast (TPWD 2009f). 

2.4.1.2 Terrestrial Resources – Transmission Lines 

Transmission corridors that originate at the STP site pass through forested, agricultural, and 

grass lands typical of Texas coastal prairie. The transmission lines and associated corridors are 

managed by four transmission service providers as described in Section 2.2. Only a 20-mi 

section of the Hillje transmission line would be disturbed by activities related to building the 

proposed Units 3 and 4. These activities would require replacing towers and upgrading the 

existing transmission lines along this section. Current transmission line corridor management 

involves mechanical, manual, and chemical methods to limit vegetation encroachment on 

transmission corridors. 

The existing transmission lines generally pass through typical habitats associated with the 

coastal prairie region of east Texas—agricultural fields, pasture/rangeland, and some forests. 

However, the westward transmission lines reach into the Edwards Plateau with different habitats 

such as Edwards Aquifer springs and karst areas (STPNOC 2010a). The 20-mi STP-to-Hillje 

corridor passes primarily through agricultural lands—the majority of the land in the corridor 

(>95 percent) is currently used for agriculture and rangelands (STPNOC 2010a). Wildlife using 

agricultural and rangeland habitats in the STP-to-Hillje corridor areas are expected to be similar 

to those using the disturbed and maintained habitats found on the STP site, such as white-tailed 

deer, eastern cottontail, and raccoon. Depending on the condition of the fields (flooded or dry) 

and the types of crops grown, a wide variety of the birds common to the interior of the coastal 

plain of Texas could use the corridor habitats. 
Affected Environment 

February 2011 2-57 NUREG-1937 

2.4.1.3 Important Terrestrial Species and Habitats 

This section describes Federally and State-listed proposed, threatened, and endangered 

terrestrial species, any designated and proposed critical habitat, and ecologically important 

species or habitats, and commercially and recreationally valuable species that may occur in the 

vicinity of the STP site or within the vicinity of the 345-kV powerline that would be upgraded 

between the STP site and Hillje Substation. A list of Federally and State-listed species 

occurring in counties (Matagorda and Wharton) that contain the site and the 345-kV 

transmission line to be upgraded was obtained from the U.S. Fish and Wildlife Service (FWS) 

county listings for the State of Texas, and the TPWD (2008a). Location information was 

obtained from the TPWD, Wildlife Division, Diversity and Habitat Assessment Programs 

(Texas Natural Diversity Database 2009). 

Important Terrestrial Species Site and Vicinity 

Matagorda County has 24 terrestrial species that are either Federally or State-listed as 

endangered or threatened (TPWD 2008a; FWS 2009a). Areas on the STP site that would be 

affected by building Units 3 and 4 were investigated by contract biologists working for the 

applicant to determine the presence or absence of state or Federally listed fauna and flora, 

evaluate whether suitable habitat exists for these species and assess potential nesting areas 

and flyways. 

Federally Listed Species 

The Federally listed wildlife species with recorded occurrences in Matagorda and Wharton 

Counties are shown in Table 2-9. Only the American alligator (Alligator mississippiensis), listed 

as threatened under the Federal Endangered Species Act (ESA), has been observed on the 

STP site. There are no Federally listed plant species known to occur in Matagorda County. 

Table 2-9. Federally Listed Terrestrial Species Identified by FWS as Occurring in the Vicinity 

of the STP Site and the STP-to-Hillje Transmission Corridor 

 Scientific Name 

Federal 

Status 

State 

Status 

Matagorda 

County 

Wharton 

County 

Birds 

Piping plover Charadrius melodus LT T Y 

Whooping crane Grus americana LE E Y Y 

Northern Aplomado falcon Falco femoralis septentrionalis LE E Y 

Reptiles 

American alligator Alligator mississippiensis DM, SAT - Y 

Source: FWS 2009a 

LT = Federally listed as threatened; LE = Federally listed as endangered; DM = Delisted, monitor; SAT = Federally 

listed as threatened due to similarity of appearance; T = State-listed as threatened; E = State-listed as endangered; 

Y = occurs in the county. 
Affected Environment 

NUREG-1937 2-58 February 2011 

The recently Federally delisted bald eagle (Haliaeetus leucocephalus) is also known to occur on 

site and active nesting sites have been located within and relatively close to the STP site 

boundaries. The bald eagle will remain Federally protected under the Bald and Golden Eagle 

Protection Act (16 USC 668-668d) and the Migratory Bird Treaty Act (16 USC 703, et seq.). It is 

also currently listed as a threatened species by the State of Texas and its occurrence and 

habitat use on the STP site is discussed with other State-listed species. The recently Federally 

delisted brown pelican (Pelecanus occidentalis) was also observed near the MCR. On 

November 17, 2009, (74 FR 59443) the FWS removed the brown pelican from the Federal List 

of Endangered and Threatened Wildlife due to recovery. Brown pelicans are listed as an 

endangered species by the State of Texas, and their occurrence and habitat use on the STP 

site is discussed with other State-listed species. 

American Alligator — In 1967, the American alligator was classified by FWS as Federally 

endangered throughout its range, including Texas. By 1987, following several reclassification 

actions in other states, the American alligator was pronounced fully recovered, and was 

reclassified to “threatened based on similarity of appearance” to the American crocodile 

(Crocodylus acutus) in the remainder of its range (52 FR 21059). American alligators can be 

found throughout the Southeast from the Carolinas to the Texas and north to Arkansas 

(FWS 2008). Alligators generally live in wetlands and alligators commonly occur in the wetlands 

and near open ditches and waterways on the STP site. Operation of STP Units 1 and 2 has not 

been shown to adversely affect the American alligators found on the site. 

Piping Plover — The Northern Great Plains population of piping plover (Charadrius melodus) 

was listed as threatened (50 FR 50726) due to excessive hunting during the 19th century and 

remains threatened as a result of flood control and water regulation that destroys or degrades 

the vegetated sandbars and river islands used for nesting. This population of plovers winters 

primarily along the Gulf Coast in Texas, Louisiana, Alabama, and Florida and critical habitat has 

been designated in these states for wintering habitat. In winter, these birds inhabit beaches, 

mudflats, and sandflats along the Gulf of Mexico as well as barrier island beaches and spoil 

islands on the Gulf Intercoastal Waterway. Piping plovers overwinter along Matagorda Bay and 

Matagorda Peninsula, approximately 7-8 mi south of the STP site (66 FR 36038). 

Whooping Crane — The whooping crane (Grus americana) was listed as threatened with 

extinction in 1967 and listed as endangered in 1970. The Aransas-Wood Buffalo National Park 

Population (AWBP) of cranes nests in Wood Buffalo National Park in Canada and winters in 

coastal marshes at the Aransas National Wildlife Refuge in Texas approximately 35 mi south of 

the STP site (Figure 2-20). These birds arrive on the Texas coast between late October and 

mid-December and spend approximately 6 months on the wintering grounds at Aransas 

National Wildlife Refuge. Whooping cranes forage primarily in brackish bays, marshes, and salt 

flats, feeding on blue crabs (Callinectes sapidus), clams, and fruits of wolfberry (Lycium spp.). 

Although birds move to uplands in the refuge to feed on acorns, snails, crayfish and insects, 

they return to the salt marshes in the evening to roost. Use of uplands or croplands adjacent to 
Affected Environment 

February 2011 2-59 NUREG-1937 

Figure 2-20. Locations of Wildlife Refuges and Critical Habitat Within 50 mi of the STP Site 

the refuge is rare (TPWD 2003). The whooping crane has not been observed on the STP site 

and is not likely to use the inland habitats found onsite. These birds may migrate through the 

Central Flyway (as described below) and fly over the STP site, but are unlikely to reside at the 

STP site or to use agricultural lands found in the STP-Hillje transmission corridor. 

Northern Aplomodo Falcon — The northern Aplomado falcon has been observed within 10 mi of 

the STP site, but has not been found on the STP site. A recovering population of the Federally 

endangered northern Aplomado falcon is located on Matagorda Island, which is part of the 

Aransas National Wildlife Refuge Complex, but no known nest sites are located within the 
Affected Environment 

NUREG-1937 2-60 February 2011 

vicinity of STP. Several Aplomado falcons have been observed during CBC bird surveys on the 

Mad Island Marsh during the past several years (NAS 2009). 

State-Listed Species 

The TPWD is responsible for maintaining lists of rare species in Texas. Species listed as 

threatened and endangered by TPWD with the potential to occur in Matagorda and Wharton 

County are documented in Table 2-10. 

TPWD identified protected species potentially occuring in Matagorda County and Wharton 

County, and several have been subject to loss of their specific habitats as humans settled the 

area and altered the natural landscape. The decline of the red wolf (Canis rufus) has been 

linked to changes in land use and the predominance of agricultural use in east Texas, which has 

reduced forested habitats and enhanced habitats for the coyote (C. latrans). Habitat loss and 

degradation resulted in a population overlap for these two species, and interbreeding between 

the two canine species has effectively resulted in the extirpation of the red wolf from Texas 

(Davis and Schmidly 1994). Likewise, habitat has declined for the ocelot (Leopardus pardalis), 

and ocelots are now limited to a few isolated areas in southern Texas (TPWD 2003), with none 

occurring near the STP site. The Louisiana black bear (Ursus americanus luteolus), one of 

16 subspecies of American black bear, was once common in the forests of eastern Texas. 

However, this subspecies was presumed to be extirpated from this area by the 1940s, and a 

resident breeding population does not currently exist in eastern Texas (TPWD 2003). The 

Eskimo curlew (Numenius borealis), which used to commonly migrate through the Texas 

coastal plains in March and April, has also been a victim of overhunting and the conversion of 

open and coastal prairie habitats to agriculture. This species was once an abundant spring 

migrant across the Texas coastal prairie but may now be extinct (TPWD 2003). As a result of 

population declines and possible extirpation and extinction, the red wolf, ocelot, Louisiana black 

bear, and Eskimo curlew would not be expected to occur in the vicinity of the STP site or 

associated transmission lines. 

The bald eagle, brown pelican, wood stork, white-faced ibis, reddish egret (Egretta rufescens), 

sooty tern (Sterna fuscata), peregrine falcon (Falco peregrinus), and white-tailed hawk 

(Buteo albicaudatus) are listed by the State of Texas and are known to occur in the region. With 

the exception of the sooty tern and the wood stork, these species have all been observed on the 

STP site during recent winter CBC efforts or during site surveys. Bald eagles are present yearround throughout Texas as spring and fall migrants, breeders, or winter residents. Breeding 

populations occur primarily in the eastern half of the State and along coastal counties from 

Rockport to Houston (TPWD 2003). The bald eagle occurs on the STP site, and an active bald 

eagle nest is located near its eastern boundary in remote woodlands near the Colorado River. 

This nest site was first reported in 2004 (STPNOC 2010a, 2008b). A second bald eagle nest is 

located within 6 mi of the STP site (Texas Natural Diversity Database 2009). 
Affected Environment 

February 2011 2-61 NUREG-1937 

Table 2-10. State-Listed Species Occurring or Potentially Occurring in the Region of the STP 

Site and the STP-to-Hillje Transmission Corridor

Common Name Scientific Name 

State 

Status 

Matagorda 

County 

Wharton 

County 

Birds 

Bald eagle Haliaeetus leucocephalus T Y Y 

Brown pelican Pelecanus occidentalis E Y 

Eskimo curlew Numenius borealis E Y Y 

Peregrine falcon Falco peregrinus T Y Y 

Reddish egret Egretta rufescens T Y 

Sooty tern Sterna fuscata T Y 

White-faced ibis Plegadis chihi T Y Y 

White-tailed hawk Buteo albicaudatus T Y Y 

Wood stork Mycteria americana T Y Y 

Interior least tern (Sternula antillarum athalassos) E Y 

Attwater’s prairie chicken (Tympanuchus cupido attwateri) Y 

Mammals 

Louisiana black bear Ursus americanus luteolus T Y 

Ocelot Leopardus pardalis E Y 

Red wolf Canis rufus E Y 

Reptiles 

Smooth green snake Liochlorophis vernalis T Y 

Texas horned lizard Phrynosoma cornutum T Y Y 

Texas scarlet snake Cemophora coccinea lineri T Y 

Texas tortoise Gopherus berlandieri T Y 

Timber/canebrake rattlesnake Crotalus horridus T Y Y 

Plants(a) 

Coastal gay-feather Liatris bracteata 

Threeflower broomweed Thurovia triflora 

Source: TPWD 2008a 

(a) The plant species included in this table are species of concern in the state of Texas that were identified as being 

of interest by the TPWD (STPNOC 2008f). 

DL= delisted, E= endangered, T = threatened, Y= yes or present. 

Brown pelicans, also called American brown pelican or common pelican, are listed as an 

endangered species by the State of Texas. This species inhabits the Atlantic, Pacific, and Gulf 

Coasts of North and South America and is found on the Gulf Coast of Florida, Alabama, 

Louisiana, Texas, Mississippi, and Mexico. Since the 1960s, the brown pelican has made a 
Affected Environment 

NUREG-1937 2-62 February 2011 

gradual comeback in Texas from fewer than 10 breeding pairs to an estimated 4097 breeding 

pairs in 2005 in 12 colonies (73 FR 9408). Most of the breeding pairs in Texas occur on Pelican 

Island in Corpus Christi Bay, Nueces County, and Sundown Island near Port O’Connor in 

Matagorda County. Smaller colonies occasionally nest on Bird Island in Matagorda Bay, on 

Dressing Point Island in East Matagorda Bay, and on islands in Aransas Bay (TPWD 2003). A 

breeding colony also exists on Little Pelican Island in Galveston Bay (Glass and Roach 1997). 

Brown pelicans inhabit warm coastal marine and estuarine environments of the Gulf of Mexico 

(Cornell 2009b) and are rarely found residing in inland habitats. Brown pelicans typically forage 

in shallow waters within 12 mi of nesting sites during breeding, and rarely venture more than 

45 mi offshore. Brown pelicans nest on small, isolated coastal islands in Texas where they are 

safe from predators. Their diet consists almost entirely of fish and is primarily menhaden 

(Brevoortia tyrannus) and mullets (TPWD 2003). The brown pelican has been observed at the 

MCR and the Lower Colorado River, and may use water bodies on the site for resting, foraging, 

and drinking. Brown pelicans nest within Matagorda Bay and the GIWW, which is relatively 

close to the site (within 10 mi). 

Wood storks historically were observed in the emergent wetlands and bottomland forest 

wetlands on STP (NRC 1975) but would not be likely to use the scrub-shrub and grassland 

habitats that exist within the disturbance footprint. Nesting of wood storks has been restricted to 

Florida, Georgia, and South Carolina; however, they may have formerly bred in most of the 

southeastern United States and Texas. A second distinct, non-endangered population of wood 

storks breeds from Mexico to northern Argentina. Storks from both populations move northward 

after breeding, with birds from the Mexico region moving up into Texas and Louisiana and as far 

north as Arkansas and Tennessee along the Mississippi River Valley (FWS 2009c). 

The white-faced ibis and the reddish egret are both wading birds that frequent marshes and 

ponds and are likely to use the managed prairie wetland habitat found on the STP site. The 

white-faced ibis seems to prefer freshwater marshes, where it can find insects, newts, leeches, 

earthworms, snails, and especially crayfish, frogs, and fish (TPWD 2009d). Reddish egrets use 

their long, spear-like bills to stab their prey, which most often consists of small fish, frogs, 

tadpoles, and crustaceans in salt and brackish water wetlands (TPWD 2009e). The white-tailed 

hawk could potentially use a variety of the habitats found on the STP site for hunting and 

resting. No known nesting sites were found during recent ecological surveys of the proposed 

plant site and facilities. 

Peregrine falcons have a wide and diverse distribution and the Texas Gulf coast is the spring 

staging area for peregrine falcon migration in the Western hemisphere. The peregrine falcon 

may also use a variety of habitats found on the STP site for hunting and perching. Fifteen 

peregrine falcons were noted in the total Mad Island Marsh CBC, but no known nesting sites 

were found during recent ecological surveys of the STP site (STPNOC 2010a) or recorded in 

TPWD databases (Texas Natural Diversity Database 2009). The coastline plays an important 
Affected Environment 

February 2011 2-63 NUREG-1937 

role in the survival of migrating peregrines. Birds take advantage of abundant prey along the 

open coastline and tidal flats to accumulate stores of fat (TPWD 2003). In Texas, the American 

peregrine is found primarily in the Trans-Pecos Region; the Arctic peregrine nests in Alaska, 

Canada, and Greenland, and migrates through Texas to South America for winter 

(TPWD 2003). 

The sooty tern is a pelagic species that is found across tropical oceans. In eastern North 

America, this species nests on islands on islands in the Gulf of Mexico from Texas to Louisiana 

(NatureServe Explorer 2009a). This species is not likely to use or occur in the habitats found on 

the STP site. The sooty tern has not been observed during CBC surveys or any ecological 

surveys of the STP site and vicinity. 

Of the State-listed reptiles that could occur on the STP site, the most likely to be found in the 

available habitats would be the smooth green snake (Liochlorophis vernalis), the Texas scarlet 

snake (Cemophora coccinea lineri), and the Texas tortoise (Gopherus berlandieri). The smooth 

green snake prefers coastal short-grass prairie habitats. The Texas scarlet snake prefers sandy 

soils and occurs in scrub-shrub and mixed hardwoods (ENSR 2007b). The Texas tortoise 

prefers scrub and grassland habitats. None of these species were encountered in surveys of 

the proposed project areas, and the TPWD database has no known locations for these species 

within the vicinity of the site (Texas Natural Diversity Database 2009). 

The Texas horned lizard (Phrynosoma cornutum) prefers open, arid and semi-arid regions with 

sparse vegetation, including grass, cactus, scattered brush, or scrubby trees. The timber 

rattlesnake (Crotalus horridus) could potentially use a variety of habitats on the site including 

flood plains, deciduous woodlands, and swamps where dense ground cover occurs. Neither of 

these species was encountered in any biological surveys of the proposed project areas, and the 

TPWD database has no known locations for these species within the vicinity of the site (Texas 

Natural Diversity Database 2009). 

Two plant species of concern were identified by the TPWD with the potential to occur on or near 

the STP site: coastal gay-feather (Liatris bracteata) and threeflower snakeweed 

(Thurovia triflora), which are both endemic species to the coastal prairies in south Texas. 

These two species occur on the nearby Clive Runnells Family Mad Island Marsh Preserve 

(TPWD 2007). These plant species occur within coast prairie grasslands, in sparsely vegetated 

spots with clayey to silty soils (NatureServe Explorer 2009b). Neither of these plant species 

was found during biological surveys of the proposed project area. Coastal gay-feather does 

occur within 6 mi of the STP site (Texas Natural Diversity Database 2009). 

Ecologically Important Species and Habitats 

Ecologically important species and habitats in the vicinity of the STP site include several 

important refuges and preserves listed below and those wetlands on the STP site that provide 
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NUREG-1937 2-64 February 2011 

significant habitat for flora and fauna. Wetlands that would be expected to provide important 

habitat onsite include the Texas Prairie Wetland Project, the emergent wetlands associated with 

Kelly Lake, and the wetlands found adjacent to the dredge spoils disposal area. Other smaller 

wetland areas on the site also provide limited habitat for a variety of wildlife. 

The Texas Prairie Wetland Project in the northeast portion of the STP site is approximately 

200 yards from the new switchyard site. Here, water impoundments are managed to create 

foraging habitat for wintering waterfowl, wading birds, and shorebirds. These impoundments 

are included as a viewing stop on the Great Texas Coastal Birding Trail that spans the entire 

Texas Gulf (TPWD 2009b). 

The STP site lies within the Central Flyway migration route—a major migratory corridor for 

neotropical migrants and other birds. Thousands of migrating birds, especially waterfowl, fly 

south from cooler regions of the North American continent and visit or winter in this coastal area 

(STPNOC 2009a). This region of Texas is also an important stopover point for other migratory 

species traveling to or from Central and South America as part of the trans-Gulf migration. 

Crossing the Gulf of Mexico is a dangerous and energetically expensive phase of the migration 

process, requiring a long, non-stop flight (Simons et al. 2004) and making it a limiting factor for 

some bird populations. Resting and foraging areas near the Gulf Coast are critical to ensure 

that trans-Gulf migratory birds can continue their migration after recovering. 

In addition to lying within the Central Flyway migration route, the region around STP contains 

three important wildlife areas. The Mad Island WMA (managed by TPWD) is approximately 

3 mi due south of the STP site and was established to preserve coastal wetland habitat for 

wintering waterfowl. This 7200-ac management area consists of fresh to brackish marshes with 

sparse brush and flat coastal prairie (STPNOC 2010a). The area provides beneficial habitat for 

many wildlife species including sandhill cranes (Grus canadensis), bobcats, gray fox, raccoon, 

river otter (Lontra canadensis), mink (Neovison vison), armadillo, rabbits, and numerous other 

species. Hunting is allowed for feral hogs, alligators, and waterfowl through special permits 

(TPWD 2008b). 

The 7063-ac Clive Runnells Family Mad Island Marsh Preserve is approximately 4 mi southwest 

of the STP site and contains both upland prairie and a variety of coastal wetlands 

(STPNOC 2010a). The preserve, owned and operated by The Nature Conservancy, is actively 

managed to enhance rice fields and wetlands for resident and migratory waterbirds. Nearly 

250 species of birds—including migrating and resident songbirds, shorebirds, colonial nesting 

birds, and wading birds—use the area for feeding, resting and roosting. 

The Big Boggy National Wildlife Refuge borders Matagorda Bay approximately 9 mi southeast 

of the STP site. It consists of more than 4500 ac of rice fields, managed impoundments, and 

salt marsh habitat, and was established to preserve habitat for neotropical migrating birds in the 
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February 2011 2-65 NUREG-1937 

fall and spring, wintering waterfowl, and other bird life (STPNOC 2010a; FWS 2009d). Within 

the refuge, Dressing Point Island is an important bird rookery for many species of waterbirds, 

including the State-listed brown pelican. 

Commercially and Recreationally Valuable Species 

Commercially and recreationally valuable terrestrial species found at STP include game 

species, such as white-tailed deer, feral pigs, rabbits, gray squirrel, northern bobwhite quail, 

mourning dove, and numerous species of waterfowl (ENSR 2008a). Of these, deer, waterfowl, 

and mourning doves are considered common on the STP site (ENSR 2008a). Mourning doves 

likely use a variety of habitats at STP including croplands and pastures, grasslands, and open 

hardwood forests. The birds feed on cereal grains, and grass and forb seeds on the ground 

(Cornell 2009a). White-tailed deer are also likely to use a variety of habitats at the STP site 

including grasslands, shrublands, and open forest, but require shrubs and woody vegetation for 

browse (TPWD 2008c). No hunting or trapping is allowed on the STP site, and no travel 

corridors for game species cross the STP site, with the exception that migratory waterfowl use 

the MCR and other site impoundments and wetlands during migration. The Texas Gulf Coast is 

one of the most important wintering and migration habitats in North America for continental 

populations of waterfowl, shorebirds, and other wetland-dependent migratory birds. Although 

no hunting is allowed on the STP site, contractors are sometimes hired by the applicant to 

remove feral pigs from the STP site and reduce the population to avoid damage to the soils on 

the reservoir embankment and destruction of habitats by the pigs (STPNOC 2010a). 

Invasive Species and Pests 

Although the STP site hosts such potential disease vectors as ticks and mosquitoes, no vectorborne diseases have been reported to STPNOC (STPNOC 2010a). Invasive plant species are 

found on the STP property—for example yaupon and McCartney rose (Rosa multiflora) 

commonly occur. Feral pigs can become a pest species on the STP site when their foraging 

and rooting activities damage soils and plants. 

Important Terrestrial Species and Habitats— Transmission Lines 

The proposed upgrade of the transmission system includes replacing some of the towers and 

replacing conductors along the 20-mi corridor that runs between the STP site and the Hillje 

Substation, located in the southwestern corner of Wharton County, just across the border from 

Matagorda County. The corridor is 400 ft wide and 20 mi long and terminates at the Hillje 

Substation. The majority of the land in the corridor (more than 95 percent) is currently used for 

agriculture and rangelands. 

Federally and State-listed Species

No Federally listed species (Table 2-9) except the American alligator are known to occur within 

2 mi of the 20-mi transmission corridor. Two important species, the coastal gay-feather (State 
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NUREG-1937 2-66 February 2011 

species of concern) and the bald eagle (State threatened species) are known to occur within 

2 mi of the corridor (Texas Natural Diversity Database 2009). 

The interior least tern (Sterna antillarum athalassos) is listed by TPWD as occurring or 

potentially occurring in Wharton County, although the FWS does not include the interior least 

tern in their county listing for Wharton. The subspecies is Federally listed only when inland 

(more than 50 mi from a coastline) where it may nest along sand and gravel bars within braided 

streams (TPWD 2003). This species has not been observed on the STP site or during CBC 

surveys of the surrounding areas. Its occurrence is unknown in the vicinity of the transmission 

corridor. 

The Attwater’s prairie chicken (Tympanuchus cupido attwateri) is also listed by TPWD as 

occurring or potentially occurring in Wharton County, although the FWS does not include this 

species in their county listing for Wharton. Habitat loss and alteration are the primary reasons 

for population decline of the Attwater’s prairie chicken in eastern Texas—in 2003, fewer than 

60 birds remained in two fragments of habitat located in Galveston and Colorado Counties. 

This species has not been observed on the STP site or during CBC surveys of the surrounding 

areas. Disturbed habitats and agricultural or managed rangeland habitats found with the 20-mi 

corridor are not suitable habitat for this species, which requires tall prairie grasslands 

(TPWD 2003). 

Ecologically Important Species and Habitats—Transmission Lines

The STP-to-Hillje transmission corridor lies within the Central Flyway migration route-- a major 

migratory corridor for neotropical migrants and other birds. Because the transmission corridor 

leaves the site and travels to the north, the southern end is less than 10 mi from the Mad Island 

WMA and the Clive Runnels Mad Island Marsh Preserve. The corridor does contain a small 

amount of wetland habitat (~9 ac) as identified by the National Wetland Inventory data for the 

corridor (FWS 2010). No areas designated by the FWS as a critical habitat for endangered or 

threatened species are crossed by any of the corridors leaving STP nor do they cross any State 

or Federal parks, wildlife refuges or preserves, or WMAs (STPNOC 2008a). 

Commercially and Recreationally Important Species

Game species common to the region that are likely to use the lands traversed by the 

transmission line corridor include those species commonly found in agricultural lands like deer, 

rabbits, squirrels, mourning dove, and possibly bobwhite quail. Vegetation management 

activities employed to maintain the corridor are unlikely to disturb these animals for periods 

much longer than the duration of the activity and vegetation management could actually benefit 

game species by providing more open habitats (STPNOC 2010a). 
Affected Environment 

February 2011 2-67 NUREG-1937 

2.4.1.4 Terrestrial Ecology Monitoring 

STPNOC does not conduct any routine monitoring of the terrestrial resources on the site. 

Regulatory agencies have not required ecological monitoring of the STP site or its associated 

transmission corridors since the period of reservoir filling (mid 1980s) and there is no ongoing 

monitoring of terrestrial resources on the site. The proposed location of Units 3 and 4 consists 

primarily of previously developed lands (warehouses, parking lots, laydown yards, etc.), a 

mowed field, and a relatively open shrubland area dominated by sea myrtle and bluestem 

grasses (STPNOC 2010a). Several biological surveys were recently conducted by the 

applicant’s contractor on the proposed plant area to identify the habitats and species present. 

Additional work has been done to map and delineate important wetlands and associated habitat 

on the site (Corps 2009b; ENSR 2008a; STPNOC 2008c). Pedestrian surveys of the proposed 

project areas found no threatened and endangered species or other important species 

occupying the area (STPNOC 2010a). 

Transmission line corridors that originate at the STP site pass through forests, agricultural 

areas, and grasslands typical of the Texas coastal prairie. As described in Section 2.2.2, the 

transmission lines and three associated corridors are managed by four transmission service 

providers (STPNOC 2010a). Only a 20-mi section of the Hillje transmission line corridor would 

be disturbed by building activities related to replacing towers and upgrading the existing 

transmission lines. The transmission system associated with existing Units 1 and 2 is 

maintained by the American Electric Power (AEP) Texas Central Company (TCC), which 

maintains the corridor from STP to the Hillje Substation. Current transmission line corridor 

management involves mechanical, manual, and chemical methods to limit vegetation 

encroachment on transmission corridors. These vegetation management activities are intended 

to reduce safety hazards from tall vegetation and minimize any potential disruptions to power 

transmission. AEP has procedures in place to document transmission line mortalities of large 

birds, should they occur, and to deal with bird nests found in hazardous locations along the 

corridors (STPNOC 2010a, 2009g).

2.4.2 Aquatic Ecology 

This section describes the aquatic environment and biota in the vicinity of the STP site and 

other areas likely to be affected by building, operating, or maintaining the proposed Units 3 

and 4. The section describes the spatial and temporal distribution, abundance, and other 

structural and functional attributes of biotic assemblages on which the proposed action could 

have an impact and also identifies “important” or irreplaceable aquatic natural resources and the 

locations that might be affected by the proposed action. 

2.4.2.1 Aquatic Resources of the Site and Vicinity 

Approximately 57.5 percent of the 12,220 ac STP site is covered in water (STPNOC 2010a). 

The onsite aquatic communities occur in several sloughs, drainage areas, wetlands, Kelly Lake, 
Affected Environment 

NUREG-1937 2-68 February 2011 

the ECP for existing Units 1 and 2, and the MCR. Within the vicinity, the major aquatic 

communities occur in the Colorado River and Matagorda Bay. 

Sloughs, Drainage Areas, Wetlands, and Kelly Lake 

Little Robbins Slough is a stream that flows across the site, from the northwest corner, along the 

western edge of the MCR embankment, and then out the southwest corner. This water flow is 

critical to the function and structure of the marshes below the site (Mad Island WMA and Clive 

Runnells Family Mad Island Marsh Preserve) flowing into GIWW. The slough is the major 

source of freshwater to the marshes, and the marshes are a nursery for juvenile fish and 

shellfish. During the building of the MCR, the slough was altered extensively (up to 65 percent 

of the drainage area for the slough in the southern boundary of the site was removed) and 

channelized into its current configuration (NRC 1975). The aquatic community in Little Robbins 

Slough from below the southern boundary of the site to Matagorda Bay was evaluated from 

1973-74, to establish a baseline for the evaluation of the system after it was built. The results of 

this study and the evaluation of potential impacts from building the MCR indicated that there 

would be as much as 24 percent reduction of the annual freshwater runoff into the marshes, 

leading to potentially significant displacement of freshwater species and reduction of the nursery 

for estuarine-dependent organisms (NRC 1975). However, as a result of seepage flow from the 

MCR into the slough, subsequent studies after the MCR was built and prior to operation 

estimated the total long-term average annual reduction of freshwater input into the marshes to 

be 6 percent. The reduction in flow of freshwater from the slough into the marshes and any 

subsequent changes in salinity or nutrient input were not expected to alter the structure and 

function of the upper marsh aquatic community (NRC 1986). 

The site has numerous drainage areas, including constructed drainage ditches, which vary in 

water flow and volume that are tied to rain events. The Final Environmental Statements (FESs) 

for the construction and operation phases of Units 1 and 2 (NRC 1975, 1986) included a 

description of the aquatic community at a number of these areas around the site. The most 

common species listed include: grass shrimp (Palaemonetes kadiakensis; also known as 

Mississippi grass shrimp), crayfish (possibly of several genera), blue crab, red shiner 

(Cyprinella lutrensis), mosquitofish (Gambusia affinis), silverband shiner (Notropis shumardi), 

sailfin molly (Poecilia latipinna), green sunfish (Lepomis cyanellus), warmouth (L. gulosus), 

bluegill (L. macrochirus), white crappie (Pomoxis annularis), tidewater silverside (Menidia 

peninsulae), striped mullet (Mugil cephalus), and several species of killifish (Family 

Cyprinodontidae, likely Lucania spp. and Fundulus spp.). Aquatic invertebrates reported were 

primarily the early life stages of midges, beetles, mayflies, biting midges, dragonflies, and 

damselflies. The fish and invertebrates are common species along the Texas coastline, and 

most of them tend to be tolerant of salinity and water temperature fluctuations (NRC 1975, 

1986; Thomas et al. 2007; Hassan-Williams and Bonner 2009; STPNOC 2010a). 
Affected Environment 

February 2011 2-69 NUREG-1937 

In May 2007, ENSR conducted a rapid bioassessment of the MDC. At the time, the channel ran 

from the North Accession Road west across the proposed power block area for proposed Units 3 

and 4, and then turned southwest, eventually joining Little Robbins Slough (Figure 2-12). The 

MDC flowed through mostly mowed and some undisturbed fields. Its banks were uniformly 

sloped, lined with riparian vegetation, but the vegetation did not form a canopy cover across the 

ditch. The water surface width, water depth, top bank width, and substrate type (silt/clay and 

silt/clay/gravel) varied along the length of the MDC. Water temperature was 29.7o

C, and 

dissolved oxygen was 8.0 to 8.4 mg/L (aerobic conditions). There was no continual flow of water 

in the MDC; however, water depth increased during rain events, and water drained into Little 

Robbins Slough during high flows. Eleven fish taxa and three non-fish taxa were identified 

during the rapid bioassessment. The dominant fish species changed throughout the length of 

the MDC, with various sunfish species (largemouth bass [Micropterus salmoides], redear sunfish 

[Lepomis microlophus], pumpkinseed [L. gibbosus], and bluegill) being dominant closest to the 

North Accession Road, followed by sailfin mollies and sheepshead minnows 

(Cyprinodon variegatus). The mid section of the MDC was dominated by mosquitofish. Red 

eared slider (Trachemys scripta elegans), crayfish (several genera occur in the area, 

e.g., Procambarus spp.), and grass shrimp (also known as Mississippi grass shrimp) were also 

collected. All collections were conducted with seines, and no aquatic insect larvae were reported 

(ENSR 2007c; STPNOC 2010a). 

The rapid bioassessment showed that the types of aquatic organisms found in the MDC are 

good indicators of long-term effects, broad habitat characteristics, and integrated ecosystem 

conditions. The types of aquatic organisms are ubiquitous in Texas coastal wetlands along the 

Gulf in Texas. Largemouth bass are top predators, which are known to inhabit a wide range of 

habitats and pioneer areas that have recently been desiccated (Barbour et al. 1999; ENSR 

2007c). The other sunfish species are all insectivores and intermediately tolerant species 

(Barbour et al. 1999; ENSR 2007c). Mosquitofish feed on insects, zooplankton, and detritus, 

are often found in shallow coastal waters, and can tolerate a range of temperatures, salinities, 

and oxygen conditions (Ross 2001; ENSR 2007c). Sheepshead minnows are hardy species 

and capable of living in harsh environments (Barbour et al. 1999; ENSR 2007c). Sailfin mollies 

are omnivores and can survive in a range of salinities and low oxygen conditions (Barbour et al. 

1999; ENSR 2007c). These fish likely move throughout the drainage systems onsite when flow 

conditions accommodate their movement. 

Kelly Lake is located in the northeast edge of the MCR embankment, approximately 7300 yds 

from the location for Unit 3 (Figure 2-14) (STPNOC 2010a). The lake covers approximately 

34 ac and is primarily fed by drainage areas but may also receive groundwater discharge 

(STPNOC 2010a). There have been no aquatic ecology surveys in this lake during the licensing 

of existing STP Units 1 and 2 or during the recent efforts to characterize the site (NRC 1975, 

1986; STPNOC 2010a). 
Affected Environment 

NUREG-1937 2-70 February 2011 

Essential Cooling Pond 

The ECP is a small cooling pond (46 ac) and serves as the ultimate heat sink for existing 

Units 1 and 2. In 2002, a survey of the ECP found only two fish species in the waters: sailfin 

molly and sheepshead minnow. Both of these species have been found in Little Robbins 

Slough, the MDC, and Colorado River, but only the sheepshead minnow has been found in the 

MCR (ENSR 2007c, 2008b, c; STPNOC 2010a). 

Main Cooling Reservoir 

The MCR is a 7000-ac, man-made impoundment that is the normal heat sink for waste heat 

generated during operations of existing STP Units 1 and 2 (Figure 2-21). The reservoir is 

unlined, and the normal maximum operating level elevation is 49 ft above MSL (currently, the 

operating level for Units 1 and 2 is 47 ft) (STPNOC 2010a). The water level and quality 

(e.g., total dissolved solids) in the MCR is maintained by pumping water from the Colorado 

River through the RMPF. The RMPF is located on the west bank of the Lower Colorado River, 

and consists of a traveling screen intake structure, siltation basin, sharp-crested weir, and a 

1200 cfs capacity pump station. Water from the river is pulled through a coarse trash rack and 

log guides and into traveling water screens (STPNOC 2010a). A handling and bypass system 

on the traveling screens can collect fish caught on the screens and return them via a sluice 

downstream to the river (STPNOC 2010a). Water that passes through the traveling screens 

goes into a siltation basin, across a sharp-crested weir and into the pumping station. The water 

is then pumped into the northeast corner of the MCR through two buried 108-in. diameter 

pipelines (STPNOC 2010a). From the southeast corner of the MCR, water can be discharged 

through a pipeline and a seven-port diffuser back into the Colorado River downstream of the 

RMPF (STPNOC 2010a). A diverse aquatic community does exist in the MCR, but the 

organisms are not available for harvest. There is no public access or use of the MCR. The 

Corps has determined that the MCR is not waters of the United States (Corps 2009a), and the 

Corps and TCEQ have stated that the MCR is not waters of the State (TCEQ 2007; STPNOC 

2010a). 

In the FES for construction of STP Units 1 and 2 (NRC 1975), the NRC staff predicted that the 

MCR would become populated with an aquatic community as fish and other aquatic organisms 

were entrained by pumping water from the Colorado River. The NRC staff stated that initially, 

the community would resemble that in a river and then evolve into a community more typical of 

other freshwater impoundments in Texas (NRC 1975). The first survey of the aquatic 

community in the MCR was a catch-and-release fishing tournament for employees only in 1994. 

The most commonly caught species were red drum (Sciaenops ocellatus) and catfish 

(undetermined species, most likely blue catfish [Ictalurus furcatus]). Other species that were 

landed included black drum (Pogonias cromis), common carp (Cyprinus carpio carpio), 

largemouth bass, longnose gar (Lepisosteus osseus), Atlantic croaker (Micropogonias 

undulatus), and southern flounder (Paralichthys lethostigma) (STPNOC 2010a). 
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February 2011 2-71 NUREG-1937 

Figure 2-21. Location of STP with Respect to Important Aquatic Resources and the 

1975-1976 Aquatic Ecology Sampling Locations 
Affected Environment 

NUREG-1937 2-72 February 2011 

From May 2007 to April 2008, ENSR collected biological samples throughout the MCR and at the 

circulating water intake structure (CWIS) for existing Units 1 and 2 located within the MCR. The 

objective of the study was “to characterize the aquatic species within the MCR, and to evaluate 

impingement and entrainment impacts to establish, to the extent possible, relationships between 

the presence of aquatic organisms and the current (STP Units 1 and 2) intake design and 

operating parameters” (ENSR 2008b). To characterize the different aquatic zones and life 

stages of organisms found in the MCR, multiple types of sampling gear were used, including gill 

nets, trawls, beach seines, and plankton nets. Four sampling events took place over the year at 

five fixed locations within the MCR (ENSR 2008b) (Figure 2-21). Water temperature, salinity, 

and dissolved oxygen were recorded when samples were taken. At the CWIS, small mesh nets 

were used to sample impingement, and plankton nets were used to sample entrainment. 

Samples were collected over a 24-hour period, twice per month from May through September 

during the peak hot months of the summer, and once per month from October through April. The 

same water quality measurements were recorded during the CWIS sampling events (ENSR 

2008b). 

The results of the MCR sampling in 2007-2008 demonstrate that the prediction in the FES for 

construction (NRC 1986) for a diverse community of fish developing with time in the reservoir 

was mostly correct. A total of 11,605 finfish and invertebrates were collected over the duration 

of the sampling program for the MCR (Table 2-11). The most common fish species collected 

were with seines, and included threadfin shad (Dorosoma petenense, 62 percent), inland 

silverside (Menidia beryllina, 18 percent), rough silverside (Membras martinica, 12 percent), and 

blue catfish (3 percent). The macroinvertebrates were characterized using plankton tows, and a 

total of 5362 organisms were collected in the MCR. The most common species (84 percent of 

all samples) collected were Harris mud crab larvae (Rhithropanopeus harrisii), and more than 

99 percent of all sampled organisms were crustaceans (ENSR 2008b). Thus, the robust aquatic 

community that has developed in the MCR resembles more the estuarine portion of the 

Colorado River rather than a freshwater impoundment. 

During the sampling at the CWIS, very few fish species were impinged (<50 percent) or 

entrained (<1 percent). A total of 3982 organisms representing 25 fish species, 7 invertebrate 

species, and 1 reptile were collected during impingement sampling (Table 2-12). Impingement 

rates were highest during the winter and early spring months. The dominant species collected in 

the impingement samples were threadfin shad (42 percent), Harris mud crab (24 percent), blue 

crab (24 percent), Atlantic croaker (5 percent), and white shrimp (Litopenaeus setiferus, formerly 

known as Penaeus setiferus, 3 percent). A total of 207,696 organisms representing 9 different 

fish families and 12 different invertebrate classes were collected during entrainment sampling 

(Table 2-13). Entrainment rates were highest during the spring months. The dominant taxa 

collected in the entrainment samples were Harris mud crab (68 percent), unidentified decapods 

(15 percent), and harpacticoid copepods (6 percent). Less than 1 percent of the total 

composition of entrained organisms was fish eggs (ichthyoplankton) (ENSR 2008b). 
Affected Environment 

February 2011 2-73 NUREG-1937 

Table 2-11. Fish and Shellfish Collected in the MCR by Gear Type, 2007-2008 

Common Name Scientific Name Gill Net Bag Seine Trawl Total 

Finfish 

Atlantic croaker Micropogonias undulatus 17 86 103 

black drum Pogonias cromis 26 26 

blue catfish Ictalurus furcatus 308 35 50 393 

bluegill Lepomis macrochirus 31 31 

channel catfish Ictalurus punctatus 3 21 6 30 

common carp Cyprinus carpio carpio 97 9 106 

freshwater drum Aplodinotus grunniens 7 3 39 49 

gizzard shad Dorosoma cepedianum 45 28 73 

Gulf menhaden Brevoortia patronus 4 1 5 

inland silverside Menidia beryllina 2068 2068 

ladyfish Elops saurus 36 1 37 

gray (mangrove) snapper Lutjanus griseus 2 2 

naked goby Gobiosoma bosc 3 3 

needlefish Strongylura exilis 1 1 

pinfish Lagodon rhomboides 3 1 4 

red drum Sciaenops ocellatus 1 1 

rough silverside Membras martinica 1362 1362 

sheepshead minnow Cyprinodon variegatus 4 4 

smallmouth buffalo Ictiobus bubalus 2 2 

spotted gar Lepisosteus oculatus 1 2 3 

striped mullet Mugil cephalus 1 41 42 

threadfin shad Dorosoma petenense 6463 768 7231 

white mullet Mugil curema 7 7 

Invertebrates 

blue crab Callinectes sapidus 11 2 6 19 

rangia clam Rangia cuneata 3 3 

Total 515 10091 999 11605 

Source: ENSR 2008b 
Affected Environment 

NUREG-1937 2-74 February 2011 

Table 2-12. Aquatic Species Collected during Impingement Sampling in the MCR’s 

CWIS for Units 1 and 2, 2007-2008 

Common Name Scientific Name Total Number 

Finfish 

American eel Anguilla rostrata 1 

Atlantic croaker Micropogonias undulatus 182 

bay anchovy Anchoa mitchilli 3 

bay whiff Citharichthys spilopterus 2 

black drum Pogonias cromis 2 

blue catfish Ictalurus furcatus 6 

bluegill Lepomis macrochirus 9 

channel catfish Ictalurus punctatus 4 

common carp Cyprinus carpio carpio 2 

freshwater drum Aplodinotus grunniens 5 

freshwater goby Ctenogobius shufeldti 2 

gizzard shad Dorosoma cepedianum 2 

goby Gobiidae spp. 8 

Gulf menhaden Brevoortia patronus 2 

inland silverside Menidia beryllina 5 

ladyfish Elops saurus 1 

naked goby Gobiosoma bosc 13 

needlefish Strongylura exilis 2 

rough silverside Membras martinica 2 

sand seatrout Cynoscion arenarius 3 

sharptail goby Oligolepis acutipennis 2 

sheepshead Archosargus probatocephalus 1 

speckled worm eel Myrophis punctatus 1 

spot croaker Leiostomus xanthurus 1 

threadfin shad Dorosoma petenense 1668 

Invertebrates 

blue crab Callinectes sapidus 944 

brown shrimp Farfantepenaeus aztecus 10 

grass shrimp Paleemonetes pugio 33 

lesser blue crab Callinectes similis 3 

Harris mud crab Rhithropanopeus harrisii 953 

river shrimp Macrobrachium ohione 3 

white shrimp Litopenaeus setiferus 106 

Other 

flat-headed snake Tantilla gracilis 1 

Total 3982 

Source: ENSR 2008b
Affected Environment 

February 2011 2-75 NUREG-1937 

Table 2-13. Aquatic Species Collected During Entrainment Sampling in the MCR’s 

CWIS for Units 1 and 2, 2007-2008 

Common Name Taxon 

Total 

Number 

Finfish 

anchovy Anchoa spp. 30 

clupeid Clupeidae 544 

fish egg 418 

goby Gobiidae 61 

perch-like fish Perciformes 6 

naked goby Gobiosoma bosc 5 

needlefish Belonidae 3 

silversides Atherinidae 201 

wrasse Labridae 3 

Invertebrates 

amphipod Amphipoda 145 

bivalve Mollusca 1 

brachyuran decapod (zoea) Brachyura 353 

copepod Copepoda 6588 

decapod (mud crabs) Panopeidae 10798 

decapod (zoea) Decapoda 31919 

fish lice Copepoda 399 

harpacticoid copepod Copepoda 12212 

Harris mud crab Rhithropanopeus harrisii 140192 

insect Insecta 24 

midge Diptera 110 

mite or ticks Acari 12 

mysid shrimp Mysida 2660 

polychaete Annelida 4 

seed shrimp Ostracoda 78 

shrimp Caridea 1 

tongue biters Isopoda 16 

water flea Cladocera 800 

unidentified 113 

Total 207,696 

Source: ENSR 2008b 

Water quality sampling in the MCR showed that there were seasonal and spatial changes within 

the reservoir. Water temperature was the highest at the cooling water discharge area and 

gradually decreased by approximately 10°F as the water traveled through the internal levee 

system to the CWIS. The temperature through the water column did not vary much: 65.3°F to 

96.1°F for surface measurements, and 65.1°F to 95°F for bottom measurements. Through the 

year, the temperature did vary, as temperature data from trawl samples increased from an 
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NUREG-1937 2-76 February 2011 

average 86.4°F in May to 93.4°F in August and then decreased in October to 76.8°F and then to 

70.5°F in February. Salinity remained constant throughout the reservoir and the water column, 

ranging from 1.6 to 1.7 ppt. Dissolved oxygen concentrations indicated that the MCR remained 

rather well oxygenated throughout the reservoir, in the water column, and throughout the year. 

Measurements for dissolved oxygen ranged from 4.6 mg/L to 13.9 mg/L and averaged 8.3 mg/L 

over the study period. The highest dissolved oxygen concentrations were during the month of 

May, and the lowest were during the month of August (ENSR 2008b). 

Colorado River 

The Colorado River is one of the largest river systems in Texas. The river is approximately 

862 mi, extending from the high plains to the coastal marshes in Matagorda County 

(Figure 2-8). The segment of the river around STP, between Bay City and GIWW is a diverse, 

fluvial system that meanders through the coastal plain providing freshwater, sediments, and 

nutrients to Matagorda Bay (ENSR 2008c). Today, there is no direct connection between the 

Gulf of Mexico and the Colorado River. Aquatic resources associated with the Gulf of Mexico 

can move into and out of the Colorado River through the navigation channel (that connects the 

Gulf to the GIWW), the GIWW and a diversion channel to Matagorda Bay. The major shipping 

channels connect to the GIWW in the northeast through the Freeport Harbor Channel 

(Corps 2008) and in the southwest through the Matagorda Ship Channel (Corps 2007). 

The flow of the Colorado River and the Gulf of Mexico has changed with development of the 

area since the 1920s. The course of the river prior to the 1920s flowed directly into Matagorda 

Bay. In the 1930s, a delta began to form in the mouth of the river and a channel was 

constructed through Matagorda Peninsula, shunting the river flows away from the bay directly 

into the Gulf of Mexico. Then in the 1950s, the Tiger Island Channel was constructed through 

the west side of the delta, re-establishing flow between the river and the bay. The Corps 

constructed a deeper river diversion channel northwest of the Tiger Island Channel in 1990. In 

1991, two dams were constructed to divert the river flow, including one across the Tiger Island 

Channel (called the Tiger Island Cut dam, recently renamed to Parker’s Cut) and a diversion 

dam across the river channel on Matagorda Peninsula. By July 1992, all of the Colorado River 

flow was diverted into Matagorda Bay, through the GIWW and the newly constructed diversion 

channel. The changes in freshwater inflow to Matagorda Bay over time, and the changes to 

flow from the Gulf of Mexico into the Colorado River have likely influenced the aquatic 

communities historically in the river and bay (Wilber and Bass 1998). 

The Lower Colorado River has been evaluated on a limited basis with specific studies 

conducted in 1973-1974, 1975-1976, 1983-1984 associated with the licensing of existing STP 

Units 1 and 2 (NRC 1975, 1986). Baseline sampling in 1973-1974 for the construction FES was 

conducted during unusually heavy rainfall that changed the freshwater/saltwater makeup in the 

river around the proposed RMPF. Additional studies were performed in 1975-1976, prior to 

makeup water pumping, and in 1983-1984, during filling of the MCR. Below is a discussion of 
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February 2011 2-77 NUREG-1937 

the findings of the surveys performed as part of the construction FES for phytoplankton 

(e.g., algae), zooplankton (e.g., copepods), macrozooplankton (e.g., larval stages of 

crustaceans), ichthyoplankton (e.g., fish eggs) and nekton (e.g., fish or other organisms living in 

the open water column) (STPNOC 2010a). Most of the sampling locations for the 1975-1976 

are shown in Figure 2-21. The sampling locations in 1983-1984 were limited to the vicinity of 

the RMPF (NRC 1986). 

Phytoplankton: In the summer of 1973, the Lower Colorado River and an adjacent stretch of 

GIWW were surveyed for phytoplankton. The phytoplankton community was dominated by 

diatoms and cyanobacteria (blue-green algae). A total of 524 taxa representing six major 

divisions were collected (NRC 1975). Diatoms were more numerous at the bottom-water 

samples, and cyanobacteria and dinoflagellates were predominant in the water column. The 

reviewers of the study noted that the phytoplankton results indicated a “relatively stable 

environment which allows development of a moderately diverse plankton flora” 

(STPNOC 2010a). 

Zooplankton: Zooplankton was also surveyed during the 1973-1974 studies of the Lower 

Colorado River and GIWW. A total of 144 zooplankton species were collected, comprising of 

protozoans (65 species), rotifers (52 species), copepods (11 species), and cladocerans 

(6 species). The survey showed that the zooplankton community structure changed based on 

salinity, such that during periods of low river flow and strong incoming tides, species diversity 

increased at upstream stations. The study noted that estuarine species were likely carried 

further upstream than normal with the tidal pulse and were able to survive because of higher 

salinities (STPNOC 2010a). 

Macrozooplankton: The area of the Lower Colorado River and GIWW was surveyed in 

1975-1976 and 1983-1984 at stations 1 through 5 (Figure 2-21). Overall the results indicated 

that the abundance and occurrence of species in the macrozooplankton community were 

influenced by seasonal changes in the environment and with the movement of the saltwater up 

and down the river (salt wedge). Station 5, in the river near the GIWW, had the highest 

macroplankton densities, and the number of organisms decreased as samples were taken 

further up the river. In the 1975-1976 samples, both freshwater and estuarine-marine decapod 

larvae predominated the macrozooplankton community from May to September, and estuarinemarine decapods larvae dominated the community from October to December. The abundance 

and diversity of decapod larvae were lowest from January-April, where the copepod 

Acartia tonsa was most prevalent. In 1983, the most abundant zooplankton invertebrates were 

cladocerans, Malacostraca species, and copepods. But in 1984, the most abundant 

macrozooplankton invertebrates were immature stages of the Harris mud crab, ghost shrimp 

(Callianassa spp.), and jellyfish (Cnidaria) (NRC 1986). 

The macrozooplankton community also included several species of commercial importance to 

the area, including early life stages of blue crab, white shrimp, and brown shrimp 
Affected Environment 

NUREG-1937 2-78 February 2011 

(Farfantepenaeus aztecus, formerly known as Penaeus aztecus). Early life stages of pink 

shrimp (Farfantepenaeus duorarum, formerly known as Penaeus duorarum) were not reported 

and may have been included in the count of brown shrimp. The megalops stage of the blue 

crab was found at all stations but the density of the species decreased with the samples from 

further up the river. Postlarval white shrimp were found in all the samples but rarely occurred at 

stations 1-3, within the vicinity of STP intake and discharge structures. Postlarval brown shrimp 

were always found at station 5, near the GIWW, but the frequency of occurrence decreased in 

the samples from stations 1 and 2. The highest density of the early life stages of blue crab, 

white and brown shrimp was in the salt wedge at any sampling location. There was also a trend 

of higher density of early life stages of these crustaceans along the river banks as compared to 

the deeper river channel. In 1985-1986 survey study, the postlarval brown shrimp, all life stages 

of white shrimp, and megalops and juvenile stages of the blue crab were collected only 

sporadically and never in very high densities (NRC 1986). 

In 1983-1984, the sediment basin in the RMPF was sampled. The predominant species in the 

sedimentation basin were postlarval stage of white shrimp, river shrimp, and Harris mud crab 

(NRC 1986). 

Ichthyoplankton: Plankton tows were used to collect fish eggs at the five sampling stations on 

the Lower Colorado River from the GIWW to upstream of the RMPF. In 1975-1976, estuarinemarine species dominated throughout the sampling area, indicating that the results were 

influenced by an extended period of saltwater in the stations closest to the GIWW and a 

predominant salt wedge up the river. Densities of ichthyoplankton were highest from 

May-October 1975 and March-April 1976, and there was a positive trend between higher 

densities and increasing salinity. The sampling region in the river is considered an estuarine 

nursery ground for a number of commercially important species that were found during the 

survey: Gulf menhaden (Brevoortia patronus), Atlantic croaker, sand seatrout 

(Cynoscion arenarius), spotted seatrout (C. nebulosus), spot croaker (Leiostomus xanthurus, 

also called spot), sheepshead (Archosargus probatocephalus), pigfish (Orthopristis 

chrysopterus), black drum, red drum, and southern flounder. The most abundant 

ichthyoplankton species were Gulf menhaden, bay anchovy (Anchoa mitchelli), Atlantic croaker, 

and naked goby (Gobiosoma bosc). In early May and August, freshwater conditions were 

dominant, and the abundance of ichthyoplankton shifted to freshwater drum 

(Aplodinotus grunniens) and cyprinid species (NRC 1986). 

The 1983-1984 survey found that the most abundant ichthyoplankton species were bay 

anchovy, darter goby (Ctenogobius boleosoma), and naked goby. These were the only species 

collected from station 2, next to the RMPF. The temporal and spatial tends of the dominant 

ichthyoplankton species of the post-pumping sampling were similar to the trends found during 

the 1975-1976 (NRC 1986). 
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February 2011 2-79 NUREG-1937 

Nekton: Seines and trawls were used for nekton sampling at all locations along the Lower 

Colorado River in 1975-1976, and only at station 2 in 1983-1984. The most abundant species 

in the earlier study were white shrimp, Gulf menhaden, bay anchovy, croaker, and mullet. All of 

these species except for menhaden decreased in abundance as the sampling progressed up 

the river. Many of the commercially important estuarine species (e.g., red drum and southern 

flounder) were only collected at station 5. The density of menhaden changed based on location 

and sampling gear, with highest densities at station 1 from trawl samples and at station 1 seine 

samples. Bay anchovy, an estuarine resident, was the second most abundant species at 

station 5. The invertebrate species were found at all locations during 1975-1976 sampling. At 

station 1, the most abundant invertebrate species changed based on gear type: brown shrimp 

were the most abundant in trawl samples, and blue crabs were the most abundant in seine 

samples. In 1983-1984, the number of invertebrates at station 2 decreased: five shrimp (river 

and white shrimp), two blue crabs, and a crayfish (NRC 1986). Brown, pink, and white shrimp 

are of commercial importance in the vicinity of the STP site (TPWD 2002; Corps 2007), and 

while various life stages of brown and white shrimp were collected in the 1975-1976 and 

1983-1984 studies, pink shrimp were only reported once during those studies in the 1984 

impingement samples in the Colorado River (NRC 1986). 

A comprehensive aquatic survey of the Colorado River in the vicinity of the STP site was 

conducted by ENSR from June 2007 through May 2008 as part of the application process for 

the proposed Units 3 and 4 at STP (STPNOC 2010a). The goals of this study were to: 

• Determine current species richness and relative abundances for fish and 

macroinvertebrates in the Lower Colorado River study area; 

• Determine the current distribution of species associated with RMPF and the discharge 

facility; 

• Compare current data to historical data to determine if the composition of aquatic organisms 

has changed considerably since the initial existing STP Units 1 and 2 licensing; and 

• Document current salinity patterns in the Lower Colorado River (ENSR 2008c). 

Figure 2-22 and Figure 2-23 show the study area associated with the 2007-2008 aquatic 

assessment consisted of an approximately 9-mi stretch of the Lower Colorado River extending 

from the GIWW north to the FM 521 bridge, which is approximately 1.5 mi east of the MCR 

(ENSR 2008c). The river stretch was divided into three reaches, each 3 mi in length, using the 

navigation mile markers (NMM) currently in place along the river. The reaches were identified 

as Segment A (from the GIWW to NMM 3), Segment B (from NMM 3 to NMM 6), and 

Segment C (from NMM 6 to NMM 9). Segment C included both the RMPF, located just 

upstream of NMM 8, and the MCR’s discharge structure located just upstream of NMM 6. 

Sampling was conducted using gill nets, hoop nets, trawls, and bag seines to collect fish and 

invertebrate species within the different reaches of the river (ENSR 2008c). 
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NUREG-1937 2-80 February 2011 

Figure 2-22. Aquatic Ecology Sampling Locations for 2007-2008, from NMM 5 to 9 
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February 2011 2-81 NUREG-1937 

Figure 2-23. Aquatic Ecology Sampling Locations for 2007-2008, from GIWW to NMM 4 
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NUREG-1937 2-82 February 2011 

Hydrological data including salinity, dissolved oxygen, and temperature were collected during 

each sampling event in 2007-2008. In addition, hydrological data were collected at NMMs 

located at one-mi intervals on the river to help define where and how these attributes affect the 

species community within the river (ENSR 2008c). 

Biological and environmental data were used to characterize spatial and temporal patterns of 

species richness and diversity, relative abundance, and fish and macroinvertebrate size 

relationships. Species richness, diversity, and relative abundance were estimated by gear type 

for the entire study area as well as within each river reach. Simpson’s Index, Shannon-Wiener 

diversity indices, evenness, and the Jaccard coefficient of community similarity were analyses 

used to evaluate and characterize the aquatic community (ENSR 2008c). 

A total of 186 samples were collected over the year-long assessment using four sampling gears 

(65 trawls, 55 seines, 33 gill nets, and 33 hoop nets) within the approximate 9-mi study area of 

the Lower Colorado River (Table 2-14). Catch rates for each of the gears were variable from 

month to month and some trends were evident based on the season. Percent composition of 

organisms collected by each gear during the study indicated that all gears were represented by 

more than 8 species (each comprising greater than 1 percent of the total catch), and species 

composition captured by each of the gears varied considerably among seasons. Species 

richness, diversity, and evenness by river segment and gear indicated that species collected 

with trawls and seines had greater species richness (44 total species versus 18-20 species 

collected in gill nets and hoop nets); however other diversity metrics were not considerably 

different among the sampling gears. Segment A (closest to the GIWW) had the highest value of 

species richness for all gears except hoop nets. Species diversity in trawl catches varied 

moderately among the three river segments, with both the Simpson’s and Shannon-Wiener 

Index values indicate that Segment B had slightly higher diversity than Segments A and C 

(ENSR 2008c). 

Hydrological data showed seasonal trends. Surface water temperatures ranged from 11.6°C in 

January to 31.0°C in August, and bottom water temperatures ranged from 11.1°C in January to 

30.8°C in August. The difference in temperature from the surface to the bottom of the river was 

an average of 0.4°C throughout the study period, reflecting the general shallow depths in the 

system. Salinity changed by season, with lower salinities during winter and higher salinities 

during spring. Salinity readings at the surface were fairly stable ranging from 0.0 ppt to about 

7 ppt, with the highest salinities occurring downstream, in Segment A, below NMM 2, and the 

lowest in Segment C, above NMM 8 (Figure 2-22 and Figure 2-23). Salinities at mid-water 

depths were the most variable of all three depths recorded. Throughout the year, the bottom 

salinities were generally highest, ranging from 0.0 ppt to a high of 25 ppt, with the lowest 

salinities reaching further upstream. Comparison of flow rates and catch rates for all four gears 

indicates an inverse relationship between flow rate and catch rate. Dissolved oxygen ranged 

from 5-12 mg/L, with the highest measurements at the surface compared to the bottom of the 
Affected Environment 

February 2011 2-83 NUREG-1937 

river. There were no strong relationships between catch rate and dissolved oxygen or salinity; 

however, bag seine catch rates had a slight positive trend with increasing salinity (ENSR 

2008c). 

Table 2-14. Fish and Shellfish Collected in the Colorado River by Gear Type, 2007-2008 

Common Name Scientific Name 

Bag 

Seine

Gill 

Net 

Hoop 

Net Trawl Total 

alligator gar Atractosteus spatula 2 2 13 17 

Atlantic brief squid Lolliguncula brevis 1 30 31 

Atlantic croaker Micropogonias undulatus 562 1 482 1045 

Atlantic cutlassfish Trichiurus lepturus 6 6 

Atlantic seabob Xiphopenaeus kroyeri 127 127 

Atlantic spadefish Chaetodipterus faber 3 3 

Atlantic threadfin Polydactylus octonemus 6 6 

bay anchovy Anchoa mitchilli 24 264 288 

bay whiff Citharichthys spilopterus 15 2 17 

bayou killifish Fundulus pulvereus 3 3 

black drum Pogonias cromis 1 1 1 1360 1363 

blackcheek tonguefish Symphurus plagiusa 3 3 

blue catfish Ictalurus furcatus 51 22 3 677 753 

blue crab Callinectes sapidus 190 2 3 77 272 

bluegill Lepomis macrochirus 3 3 

brown shrimp Farfantepenaeus aztecus 264 192 456 

bull shark Carcharhinus leucas 6 6 

channel catfish Ictalurus punctatus 22 2 6 30 

cichlid Cichlasoma spp. 16 16 

crayfish Procambarus sp. 1 1 

crevalle jack Caranx hippos 2 2 

cyprinids Cyprinidae 1 1 

diamond killifish Adinia xenica 11 11 

flathead catfish Pylodictis olivaris 2 2 

freshwater goby Ctenogobius shufeldti 9 9 

gafftopsail catfish Bagre marinus 9 183 192 

gizzard shad Dorosoma cepedianum 8 2 52 62 

grass carp Ctenopharyngodon idella 2 1 3 

grass shrimp Palaemonetes pugio 1762 1762 

gray (mangrove) snapper Lutjanus griseus 1 1 
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NUREG-1937 2-84 February 2011 

Table 2-14. (contd)

Common Name Scientific Name 

Bag 

Seine

Gill 

Net 

Hoop 

Net Trawl Total 

Gulf killifish Fundulus grandis 15 15 

Gulf menhaden Brevoortia patronus 2960 5 2 1076 4043 

hardhead catfish Ariopsis felis 1 1 252 254 

Harris mud crab Rhithropanopeus harrisii 1 1 

inland silverside Menidia beryllina 6 6 

killifish sp. Fundulus sp. 5 5 

ladyfish Elops saurus 2 1 3 

lesser blue crab Callinectes similis 1 5 6 

lined sole Achirus lineatus 3 3 

longnose gar Lepisosteus osseus 1 1 

mosquitofish Gambusia affinis 1 1 

naked goby Gobiosoma bosc 3 3 

pigfish Orthopristis chrysoptera 1 1 

pinfish Lagodon rhomboides 11 11 

rainwater killifish Lucania parva 2 2 

red drum Sciaenops ocellatus 8 8 38 25 79 

red eared slider Trachemys scripta elegans 1 1 

river shrimp Macrobrachium ohione 10 5 15 

rough silverside Membras martinica 17 17 

sailfin molly Poecilia latipinna 150 150 

sand seatrout Cynoscion arenarius 22 5 294 321 

sharptail goby Oligolepis acutipennis 39 39 

sheepshead Archosargus probatocephalus 14 1 6 48 69 

sheepshead minnow Cyprinodon variegatus 79 7 86 

shiner Notropsis spp. 2 2 

silver jenny Eucinostomus gula 2 2 

silver perch Bairdiella chrysoura 350 350 

smallmouth buffalo Ictiobus bubalus 32 5 37 

southern flounder Paralichthys lethostigma 2 2 3 12 19 

southern stingray Dasyatis americana 1 1 

spot croaker Leiostomus xanthurus 88 1 156 245 

spotfin mojarra Eucinostomus argenteus 3 5 8 

spotted gar Lepisosteus oculatus 1 1 10 1 13 
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February 2011 2-85 NUREG-1937 

Table 2-14. (contd)

Common Name Scientific Name 

Bag 

Seine

Gill 

Net 

Hoop 

Net Trawl Total 

spotted seatrout Cynoscion nebulosus 4 53 57 

star drum Stellifer lanceolatus 86 86 

striped mullet Mugil cephalus 1676 1 1 1678 

threadfin shad Dorosoma petenense 4 7 11 

violet goby Gobioides broussonnetii 2 2 

white mullet Mugil curema 181 2 183 

white shrimp Litopenaeus setiferus 584 2870 3454 

Total 8806 106 99 8760 17771 

Source: ENSR 2008c 

Changes in the aquatic community over time in the Colorado River were evaluated using the 

results of the 1974, 1983, 1984, and 2007-2008 studies. The sampling locations and gear types 

did vary with each study, making some comparisons more difficult. Trawl samples collected 

from the GIWW to the STP site in 1974 showed that there was a moderately diverse species 

community for the lower river based on measures for species richness, diversity, and evenness. 

All three measures were slightly lower than those in similar segments of the river compared to 

the 2007-2008 study, suggesting that the diversity of aquatic species is greater now than in the 

past. Data collected during 1974 examining specific segments also indicated a diverse 

community for all three segments. The 1983-1984 trawl and seine data indicated overall lower 

species richness, diversity, and evenness relative to the present data (ENSR 2008c). Rerouting 

of the Lower Colorado River (completed in 1992) has likely contributed to these changes in 

diversity of aquatic species. 

The Jaccard coefficients of community similarity was used to determine similarities between the 

samples collected in similar reaches of the Lower Colorado River based on the presence or 

absence of taxa. For this measure, as the coefficient approaches 1.0, the more taxa in the two 

samples are the same; and for the converse, as the coefficient approaches 0, the samples have 

fewer taxa in common. In comparing applicable months and gears from the 2007-2008 data 

with samples collected during 1974, the Jaccard coefficient value was 0.44, indicating that the 

less than half of the aquatic species sampled in 1974 were the same as those found in 

2007-2008. Comparison of applicable months from the 2007-2008 data to the 1983-1984 

samples resulted in a coefficient value of 0.19, indicating that there was low similarity for these 

aquatic communities (ENSR 2008c). Comparison of data from river Segment C in 2008 with 

1974 and 1983-1984 trawl data for a similar river segment resulted in values of 0.36 and 0.37, 

respectively, suggesting a moderate level of similarity between historical and present 

communities. Comparison of data for bag seine samples from applicable months during 
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NUREG-1937 2-86 February 2011 

2007-2008 with 1983-1984 seine data resulted in coefficient values of only 0.07 and 0.11, 

suggesting low similarity between historic and present day communities in shallow waters 

accessible to seines. When 2007-2008 bag seine data for Segment C was compared to 1983 to 

1984 data from the same segment, Jaccard coefficient values increased to 0.31 and 0.33, 

suggesting moderate community similarity. Overall, present data indicate a more diverse faunal 

community than that represented by historic data in the Lower Colorado River (ENSR 2008c). 

The number and assortment of organisms collected during this study indicate that this portion of 

the Lower Colorado River supports a diverse assemblage of fauna. The regular occurrence of 

both freshwater and saltwater species, the range of macroinvertebrate and finfish fauna, and the 

sheer number of species captured among various sampling gears and river reaches provide 

evidence of a dynamic ecosystem. There was low to moderate level of similarity between the 

current 2007-2008 faunal communities and the historic communities (1974 and 1983-84) 

(ENSR 2008c). 

Matagorda Bay 

Matagorda Bay is 300 mi2 formed by a 45-mi-long barrier island-peninsula complex that is 

parallel to the Gulf of Mexico coast southeast of the STP site. The bay is connected to the 

waters on the site through the discharges of Little Robbins Slough into the marshes next to the 

GIWW, which then flows into the bay. As mentioned above, the Colorado River flows by STP 

then across the GIWW into a diversion channel into the bay. The bay is described as the 

Matagorda Bay system, and it is the third largest estuary on the Texas coast. The bay system 

includes Lavaca, East Matagorda, Keller, Carancahua, and Tres Palacios bays (Corps 2007). 

The aquatic community of Matagorda Bay system includes organisms in the open water areas 

as well as organisms over hard substrates (including oyster reefs and offshore sands). In the 

open water areas of the bay, phytoplankton (e.g., algae) are the major primary producers that 

are the main food source for zooplankton (e.g., small crustaceans), fish and benthic organisms 

(e.g., mollusks). As discussed in a recent Corps EIS (2007), a study of Lavaca Bay by the FWS 

found that phytoplankton species composition changes based on the season, with maximum 

abundance occurring in the winter and minimum in the summer, and the most dominant 

organisms were diatoms. Zooplankton composition also changed seasonally, with the greatest 

abundance during the spring and smallest in the fall. The dominant species are the copepod, 

Acartia tonsa and the barnacle nauplii (swimming juvenile life-stage of barnacles). The same 

composition of phytoplankton and zooplankton are thought to be found throughout the 

Matagorda Bay estuary (Corps 2007). 

The Matagorda Bay system supports a diverse population of aquatic organisms that are found 

in the open water column (nekton), including fish, shrimp, and crabs. The nekton assemblages 

consist mainly of secondary consumers feeding on zooplankton or juvenile and smaller 

organisms in the water column. Some of these species are resident species, spending their 
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February 2011 2-87 NUREG-1937 

entire life in the bay, whereas other species may spend only a portion of their life cycle in the 

bay. According to a summary of studies on the nekton species in the Matagorda Bay estuary, 

the dominant nekton species inhabiting the Matagorda Bay estuary include the bay anchovy, 

Atlantic croaker, brown shrimp, pink shrimp, white shrimp, hardhead catfish (Ariopsis felis), sand 

seatrout, blue crab, and Gulf menhaden. All of these species are ubiquitous along the Texas 

coast and they are unaffected by seasonal or other short-term changes (e.g., salinity). The 

abundance of these species naturally changes with the season, with biomass and number 

usually being the smallest in the fall after Gulf-ward migrations. In the winter and early spring, 

newly spawned fish and shellfish begin migrating into the bay, with the maximum biomass 

observed during the summer months (Corps 2007). Many of these species have been collected 

in the Colorado River and some in the MCR at the STP site (NRC 1975, 1986; ENSR 2008b, c; 

STPNOC 2010a). 

Areas of the Matagorda Bay estuary that are not considered open water include oyster reefs 

and offshore sands. The oyster reefs of Matagorda Bay are formed in areas where the 

substrate is hard and the current is strong enough to provide phytoplankton and nutrients to the 

oysters and carry sediment away from the organisms. The reefs are subtidal or intertidal and 

found near passes and cuts, and along the edges of marshes. The oyster reefs provide an 

ecological important function to the bay system by providing habitat to other benthic organisms 

and influencing water clarity and quality (oysters can filter water 1500 times the volume of their 

body per hour). While oysters can survive in salinities ranging from 5 to 40+ ppt, they thrive 

within a range of 10 to 25 ppt. The current distributions of oyster reefs in Matagorda Bay are 

not mapped, but the prominent locations (including commercial harvests) are in the vicinity of 

Lavaca Bay (Corps 2007). One of the goals of the diversion of the Colorado River into the bay 

is to increase mixture of freshwater in the estuary, and enhance locations of the bay for further 

reef development (Wilbur and Bass 1998). 

The offshore sands of the Matagorda Bay system include areas of open sandy substrate as well 

as regions where seagrass or attached algae grow. Much of the diverse fauna in these areas is 

buried in the sand and the organisms rely on the phytoplankton for food. Sand dollars 

(Mellita quinquiesperforata) and several species of brittle stars (Hemipholis elongata, 

Ophiolepis elegans, and Ophiothrix angulata) are some of the most common species found in 

the shallow offshore sands. The bivalves in offshore sands include the blood ark 

(Anadara ovalis), incongruous ark (A. brasiliana), southern quahog (Mercenaria 

campechiensis), giant cockle (Dinocardium robustum), disk dosinia (Dosinia discus), pen shells 

(Atrina serrata), common egg cockle (Laevicardium laevigatum), crossbarred venus 

(Chione cancellata), tellins (Tellina spp.), and the tusk shell (Dentalium texasianum). The most 

common gastropods are moon snail (Polinices duplicatus), ear snail (Sinum perspectivum), 

Texas olive (Oliva sayana), Atlantic auger (Terebra dislocata), Sallé’s auger (Terebra salleana, 

now known as Hastula salleana), scotch bonnet (Phalium granulatum), distorted triton 

(Distorsio clathrata), wentletraps (Epitonium sp.), and whelks (Busycon spp.). Crustaceans also 
Affected Environment 

NUREG-1937 2-88 February 2011 

inhabit the open sand areas, including white and brown shrimp, rock shrimp (Sicyonia 

brevirostris), blue crabs, mole crabs (Albunea spp.), speckled crab (Arenaeus cribrarius), box 

crab (Calappa sulcata), calico crab (Hepatus epheliticus), and pea crab (Pinnotheres 

maculatus). With respect to the number of individuals found in the open sands, the most 

abundant infaunal organisms are the polychaetes (Capitellidae, Orbiniidae, Magelonidae, and 

Paraonidae) (Corps 2007). 

2.4.2.2 Aquatic Resources – Transmission Lines 

Power generated from proposed Units 3 and 4 would be transmitted using existing transmission 

line corridors. Only a 20-mi section of the Hillje transmission line would be disturbed by building 

activities related to replacing towers and upgrading the existing transmission lines. The 

transmission corridors pass through forested, agricultural, and grass-lands typical of the Texas 

coastal prairie (STPNOC 2010a). The water bodies crossed by the transmission corridors 

include small rivers, small streams, agricultural ponds, drainage areas, and wetlands 

(NRC 1975). No aquatic surveys are known to have been conducted along these corridors. 

The staff’s review of the terrain along the Hillje transmission line during a pre-application site 

visit did not indicate any notable aquatic features within that region of the corridor (NRC 2008a). 

Observed water bodies included wetlands and small ponds. Aquatic species in the water 

bodies along the transmission corridors are likely similar to those communities typically found 

along the coastal plain and are likely tolerant to temporary changes in water quality 

(STPNOC 2010a). 

2.4.2.3 Important Aquatic Species and Habitats 

This section discusses important aquatic species and habitats that could be affected by building, 

operating, and maintaining the proposed Units 3 and 4 and associated transmission lines. 

Although there are no designated critical habitats for aquatic species in the vicinity of the STP 

site and associated transmission lines, this section will discuss other important habitats for 

aquatic species. 

Important Species 

This section describes important species in the vicinity of the STP site and associated 

transmission lines that could be affected by the proposed actions (Table 2-15). Such species 

include commercially and recreationally important species, species with designated essential 

fish habitat (EFH), Federally and State-listed species, and ecologically important species that 

are essential to the maintenance or survival of the other species or critical to the structure and 

function of the riverine, estuarine, and marine ecosystems. 
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February 2011 2-89 NUREG-1937 

Table 2-15. Important Aquatic Species that May Occur in the Vicinity of STP Site 

Common Name Scientific Name Type Category 

American eel Anguilla rostrata Fish State-Rare 

Atlantic croaker Micropogonias undulatus Fish Commercial; Ecological 

bay anchovy Anchoa mitchilli Fish Commercial; Ecological 

black drum Pogonias cromis Fish Commercial; Recreational 

blue catfish Ictalurus furcatus Fish Commercial; Recreational 

blue sucker Cycleptus elongates Fish State-Threatened 

bluegill Lepomis macrochirus Fish Recreational; Ecological 

channel catfish Ictalurus punctatus Fish Commercial; Recreational 

flathead catfish Pylodictis olivaris Fish Recreational 

gafftopsail catfish Bagre marinus Fish Recreational 

gray (mangrove) snapper Lutjanus griseus Fish EFH 

Gulf menhaden Brevoortia patronus Fish Commercial; Ecological 

hardhead catfish Ariopsis felis Fish Recreational 

inland silverside Menidia beryllina Fish Ecological 

king mackerel Scomberomorus cavalla Fish Recreational; EFH 

largemouth bass Micropterus salmoides Fish Ecological 

mosquitofish Gambusia affinis Fish Ecological 

red drum Sciaenops ocellatus Fish Commercial; Recreational; EFH

rough silverside Membras martinica Fish Ecological 

sheepshead Archosargus probatocephalus Fish Commercial; Recreational 

smallmouth buffalo Ictiobus bubalus Fish Recreational 

smalltooth sawfish Pristis pectinata Fish Federally & State-Endangered 

Southern flounder Paralichthys lethostigma Fish Commercial; Recreational 

Spanish mackerel Scomberomorus maculatus Fish Recreational; EFH 

spotted seatrout Cynoscion nebulosus Fish Commercial; Recreational 

striped mullet Mugil cephalus Fish Commercial; Ecological 

threadfin shad Dorosoma petenense Fish Ecological 

blue crab Callinectes sapidus Invertebrate Commercial; Ecological 

brown shrimp Farfantepenaeus aztecus Invertebrate Commercial; Ecological; EFH 

Eastern oyster Crassostrea virginica Invertebrate Commercial; Ecological 

grass shrimp Paleamonetes pugio Invertebrate Ecological 

Gulf Coast clubtail Gomphus modestus Invertebrate State-Rare 

pink shrimp Farfantepenaeus duorarum Invertebrate Commercial; EFH; Ecological 

smooth pimpleback Quadrula houstonensis Invertebrate State-Proposed Threatened 

Texas fawnsfoot Truncilla macrodon Invertebrate State-Proposed Threatened 

Western Gulf stone crab Menippe adina Invertebrate EFH 

white shrimp Litopenaeus setiferus Invertebrate Commercial; EFH 
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NUREG-1937 2-90 February 2011 

Table 2-15. (contd)

Common Name Scientific Name Type Category

blue whale Balaenoptera musculus Mammal Federally Endangered 

finback whale Balaenoptera physalus Mammal Federally Endangered 

humpback whale Megaptera novaeangliae Mammal Federally Endangered 

sei whale Balaenoptera borealis Mammal Federally Endangered 

sperm whale Physeter macrocephalus Mammal Federally Endangered 

West Indian manatee Trichechus manatus Mammal Federally & State-Endangered 

hawksbill sea turtle Eretmochelys imbricata Reptile Federally & State-Endangered 

green sea turtle Chelonia mydas Reptile Federally & State-Endangered 

Kemp’s ridley sea turtle Lepidochelys kempii Reptile Federally & State-Endangered 

leatherback sea turtle Dermochelys coriacea Reptile Federally & State-Endangered 

loggerhead sea turtle Caretta caretta Reptile Federally & State-Endangered 

Sources: NRC 1975; GMFMC 2004; LCRA 2006; Corps 2007; TPWD 2009a, b, h; NMFS 2009a; FWS 2009a

Commercial and Recreational Species 

The important commercial fisheries in Matagorda Bay target shrimp (grass, brown, and white), 

Eastern oysters (Crassostrea virginica), blue crabs, and finfish. All of these species have been 

found in the Colorado River in the vicinity of the site and in the MCR, except for oysters. The 

marine and estuarine finfish include Gulf menhaden, striped mullet, bay anchovy, spotted 

seatrout, southern flounder, and Atlantic croaker, sheepshead, and red and black drum. 

Important freshwater species included blue catfish, channel catfish (Ictalurus punctatus), 

smallmouth buffalo (Ictiobus bubalus), and bluegill (NRC 1975; LCRA 2006; Corps 2007; 

ENSR 2008b, c; STPNOC 2010a). 

The contribution of commercial catch from Matagorda Bay compared to all the harvest in the 

Texas bay systems varies based on the fishery. Matagorda Bay has one of the lowest 

percentages of the total finfish harvest of all Texas bay systems, which was less than 5 percent 

of the coast-wide landings from 1997 to 2001. Over the same time period, Matagorda Bay 

contributed more of the commercial catch of shellfish from the Texas bay systems: 24 percent 

of brown shrimp; 29 percent of white shrimp; and 13 percent of blue crabs. The contribution of 

eastern oysters commercially harvested in Texas is only about 5 percent from Matagorda Bay 

(Corps 2007). 

TPWD’s guide to fishing indicates that the following species are of recreational interest in the 

vicinity of STP site: catfish (blue, channel, flathead [Pylodictis olivaris], gafftopsail 

[Bagre marinus], hardhead), black and red drum, southern flounder, king mackerel 

(Scomberomorus cavalla), and Spanish mackerel (S. maculatus), spotted seatrout, and 

sheepshead (TPWD 2008a). All of these species have been found in the Colorado River in the 

vicinity of the site, except for the mackerel (NRC 1975; STPNOC 2010a; ENSR 2008b, c). 
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February 2011 2-91 NUREG-1937 

The following is a description of the life cycles of important recreational and commercial aquatic 

species (Table 2-15), included to facilitate understanding of how and when these species utilize 

estuarine habitat in the project area. The species that have designated EFH in the area are 

discussed further below, as well as in the EFH assessment in Appendix F. 

Commercially and Recreationally Important Fish

Atlantic croaker. The Atlantic croaker is an inshore demersal fish found from the Gulf of Maine 

to Florida and throughout the Gulf of Mexico. During their life they move throughout the area: 

eggs are laid in the water column in the marine environment; as larvae, the croakers move into 

estuarine areas and become demersal; juveniles are demersal and move into tidal rivers and 

creeks, where they spend 6 to 8 months; adult croakers are demersal and move between 

estuarine and oceanic waters, and then they spawn in the nearshore of the Gulf in September to 

May. In the vicinity of Matagorda Bay, Atlantic croakers are considered highly abundant as 

juveniles, and abundant as adults, but other life stages are not found. The youngest croakers 

feed on zooplankton, but juveniles and adults are bottom feeders, consuming benthic worms, 

mollusks, and crustaceans. Adults may occasionally eat other fish. Striped bass 

(Morone saxatillis), southern flounder, blue catfish, red drum, sheepshead and spotted seatrout 

prey on Atlantic croakers (Patillo et al. 1997; Corps 2007; TPWD 2009m). 

Texas has a valuable commercial fishery for Atlantic croakers, but not in the Matagorda Bay 

area (Corps 2007). They are commonly caught recreationally in the area, although croakers are 

not considered a popular game fish (Patillo et al. 1997). There are no limits for harvesting 

croakers in Texas (TPWD 2009o). Since these fish use marine, estuarine, and tidal rivers, they 

have often been collected during surveys of waters in and around the STP site. Atlantic 

croakers have been collected in Matagorda Bay (Corps 2007) and in the Colorado River during 

the 1975-1976 (NRC 1986) and 2007-2008 surveys (ENSR 2008c). This species was also 

collected in the MCR during the 1994 employee tournament (STPNOC 2010a) and in the 

2007-2008 survey (ENSR 2008c). 

Bay anchovy. Bay anchoy are rather small (4 in. maximum in length) schooling fish that may 

represent the greatest biomass of any fish in the estuarine waters along the Gulf Coast. They 

are a common foraging fish for other aquatic and terrestrial predators. Bay anchovy are pelagic, 

and occur throughout the water column over their life stages in estuarine and tidal river habitats. 

They are tolerant of poor water quality, and can be found in relatively anoxic conditions in 

pollution-stressed areas. Thus, shifts in population, where bay anchovy become the dominant 

species, can be an indicator of detoriating water quality. Eggs are most abundant at the surface 

of the water, while larvae, juveniles and adults are nektonic, freely swimming in the water. In 

Matagorda Bay, the adults and spawning adults are highly abundant, juveniles and larvae are 

abundant, and eggs are common. Spawning occurs in bays, estuaries, and tidal rivers in waters 

less than 20 ft deep during the spring and early summer along the Texas coast. Juveniles and 
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NUREG-1937 2-92 February 2011 

adults feed primarily on zooplankton, small crustaceans, mollusks and other fish as well as 

detritus (Patillo et al. 1997; Hassan-Williams and Bonner 2009). 

Bay anchovy are indirectly important to commercial and recreational fishing as a major food 

source for the game fish in the region (Corps 2007). This species was collected in the Colorado 

River during the 1975-1976 nekton samples (NRC 1986), the 1983-1984 ichthyoplankton 

samples (NRC 1986), and in the 2007-2008 bag seine and trawl samples (ENSR 2008c). In 

addition, bay anchovy have been found in the MCR and were collected during impingement 

studies of the MCR’s CWIS (ENSR 2008b). They have also been collected in nekton samples 

in Matagorda Bay (Corps 2007). 

Black drum. Black drum are common demersal fish species found from the Chesapeake Bay 

to Florida, and throughout the Gulf of Mexico. The species is estuarine-dependent and found 

throughout Matagorda Bay and in the tidal rivers. Eggs are pelagic and buoyant, and the larvae 

stay in the water column and are pushed by the tides into estuaries and tidal rivers. Juveniles 

prefer shallow, nutrient rich, turbid waters such as in the tidal rivers of the region. Adults often 

move in large schools, searching for food in estuaries and bays. Spawning occurs primarily in 

nearshore water and estuaries. All life stages are common in Matagorda Bay. Black drum feed 

on benthic organisms, and adults particularly feed on oysters (Patillo et al. 1997). 

Black drum are harvested commercially in Matagorda Bay, and are also an important seasonal 

recreational species in the region (Patillo et al. 1997). There are no bag or possession limits for 

the commercial harvest of black drum; however, they must be from 14 to 30 in. long 

(TPWD 2009o). The recreational bag limit for black drum is five fish per day between 14 and 

30 in. long. However, one fish over 52 in. may be retained per day as part of the bag limit 

(TPWD 2009p). Black drum have been collected in the Colorado River during the 1975-1976 

ichthyoplankton samples (NRC 1986) and mostly in the 2007-2008 trawl samples (ENSR 

2008c). This species was also collected in the MCR during the 1994 employee tournament 

(STPNOC 2010a), during 2007-2008 gill sampling around the MCR as well as in impingement 

samples of the MCR’s CWIS (ENSR 2008b). 

Bluegill. The bluegill is a native fish throughout Texas and across the eastern United States, 

and it is commonly introduced to areas for recreational purposes. In Texas, they are found in 

lakes and ponds, and while they prefer slow-moving water (e.g., streams and rivers). Younger 

fish generally utilize areas where there is cover (e.g., woody debris) while adults seek more 

open waters. Bluegill are nest builders, and spawning occurs from April through September. 

Bluegill feed primarily on insects, crustaceans, and fish but may also consume some plant 

material (Hassan-Williams and Bonner 2009; TPWD 2009m). 

Bluegills are a recreationally important species, but there are no limits for their collection 

(TPWD 2009l). The species has been collected onsite in the MDC (ENSR 2007c; 
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February 2011 2-93 NUREG-1937 

STPNOC 2010a), as well as in the MCR survey and during impingement studies of the MCR’s 

CWIS (ENSR 2008b). Bluegill were also collected in the Colorado River during the 2007-2008 

sampling (ENSR 2008c). 

Catfish. There are five catfish species that have been collected on and around the STP site: 

blue, channel, flathead, gafftopsail and hardhead catfish. Blue and channel catfish are 

commercially and recreationally important fish in the Colorado River, flathead and hardhead 

catfish are recreationally important, and gafftopsail catfish are commercially important species in 

Texas. There are commercial bag and possession limits for blue and channel catfish, and while 

there are no such limits for gafftopsail catfish, the three catfish species must be greater than 

14 in. for commercial harvest. There are recreational bag and minimum length limits for blue, 

channel and flathead catfish, but there are no posted limits for hardhead catfish (TPWD 2009l, 

o). All of these species are top predators in the food chain; however, they differ in their 

tolerance of salinity. Blue, flathead, and hardhead catfish are found in freshwater, estuarine and 

marine waters; channel catfish prefer freshwater; and gafftopsail catfish prefer estuarine and 

marine waters. Hardhead catfish are the smallest of the five species with a maximum length of 

19 in.; gafftopsail, blue, channel, and flathead catfish can grow to 34, 47, 50, and 55 in., 

respectively. The males of these species build nests, and spawning occurs in spring and 

summer as the water warms. All of the species are bottom dwellers, feeding on benthic 

crustaceans, mollusks, and other invertebrates, as well as small fish. As adults, the gafftopsail 

catfish differ in that they only consume other fish (Corps 2007; Hassan-Williams and Bonner 

2009; TPWD 2009m). 

Blue catfish were collected in the Colorado River during the 2007-2008 sampling, predominantly 

in the trawl samples (ENSR 2008c), and they were also collected in the MCR during the 1994 

employee tournament (STPNOC 2010a), in the 2007-2008 samples throughout the MCR as well 

as in impingement samples at the MCR’s CWIS (ENSR 2008b). Channel catfish were less 

common than blue catfish, but they were collected in the Colorado River during the 2007-2008 

survey (ENSR 2008c) and in the MCR during the 2007-2008 samples throughout the MCR as 

well as in impingement samples at the MCR’s CWIS (ENSR 2008b). Only two flathead catfish 

were collected in the Colorado River during 2007-2008 (ENSR 2008c). Gafftopsail were 

collected in the Colorado River during 2007-2008 (ENSR 2008c) and in open- water sampling of 

Matagorda Bay (Corps 2007). Hardhead catfish were collected in the Colorado River during 

2007-2008 (ENSR 2008c) and in nekton samples in Matagorda Bay (Corps 2007). 

Gulf menhaden. Gulf menhaden are only found in the Gulf of Mexico, typically in the estuarine 

and nearshore marine waters but the juveniles will often move up tidal rivers. They are an 

important link in the food chain between primary producers, phytoplankton and detritus, and top 

predators. Like bay anchovy, they are an important foraging fish for other aquatic and terrestrial 

predators. The species is migratory, moving in and out of estuaries over their lifetime. In 

Matagorda Bay, Gulf menhaden are highly abundant as adults and juveniles, but their other life 
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NUREG-1937 2-94 February 2011 

stages are not present. Spawning has not been observed, but the species is thought to spawn 

offshore in marine waters from October through April. Larvae feed primarily on zooplankton. 

The fish lose their teeth as they metamorphose into juveniles, and they become omnivorous 

filter feeders consuming phytoplankton, zooplankton and detritus (Patillo et al. 1997; HassanWilliams and Bonner 2009). 

Gulf menhaden are commercially important fish in the Gulf of Mexico (Patillo et al. 1997), but 

they are not harvested in Matagorda Bay (Corps 2007). The species was collected in the 

Colorado River during the 1975-1976 ichthyoplankton and nekton samples (NRC 1986) and 

during the 2007-2008 survey, particularly in the bag seines (ENSR 2008c). Gulf menhaden 

were also collected during the 2007-2008 MCR survey as well as during impingement studies of 

the MCR’s CWIS (ENSR 2008b). They were also one of the dominant species in nekton 

samples from Matagorda Bay (Corps 2007). 

Sheepshead. Sheepshead spawn offshore during March and April. The species is a broadcast 

spawner, releasing eggs and sperm into the water column for fertilization in the coastal waters. 

Larvae are pelagic as they move into the seagrass beds of the estuary, where they remain as 

plankton for 30 to 40 days, then metamorphose into juveniles. As they mature into juveniles 

they become substrate-oriented, remaining in the seagrass beds. Adults are demersal in the 

nearshore waters. In Matagorda Bay, sheepshead are abundant as adults and juveniles, but 

their other life stages are not present. Larvae are carnivorous, and juveniles and adults are 

omnivorous (Patillo et al. 1997; Corps 2007). 

Sheepshead are commercially harvested in Matagorda Bay (Corps 2007), and there are no bag 

or possession limits for harvesting, only that the fish must exceed 15 in. in length. Recreational 

catches are limited to five fish per day, and they must exceed 15 in. in length (TPWD 2009l, o). 

Sheepshead were collected in the Colorado River during the 1975-1976 ichthyoplankton 

samples (NRC 1986) and 2007-2008 survey (ENSR 2008c). They were also collected during 

impingement studies of the MCR’s CWIS (ENSR 2008b). Sheepshead was also one of the 

dominant species in nekton samples from Matagorda Bay (Corps 2007). 

Smallmouth buffalo. Smallmouth buffalo are primarily freshwater fish (Hassan-Williams and 

Bonner 2009), but they were collected in all segments of the Colorado River to the GIWW 

during the 2007-2008 survey (ENSR 2008c). They are found in streams along the U.S. east 

coast up to Pennsylvania, west to Montana, and south to Mexico. In Texas, they are found 

throughout the state with the exception of the Panhandle region. They are common in 

reservoirs and large streams with modest currents. Smallmouth buffalo are broad cast 

spawners over submerged aquatic vegetation (SAV), and they spawn from March through 

September. The species feeds primarily on the bottom, consuming insects, mollusks, 

zooplankton, periphyton and detritus (Hassan-Williams and Bonner 2009). Smallmouth buffalo 

are primarily recreationally important fish, although they are harvested for pet and livestock feed 
Affected Environment 

February 2011 2-95 NUREG-1937 

(Hassan-Williams and Bonner 2009). The species was collected during the 2007-2008 surveys 

of the MCR and the Colorado River (ENSR 2008b, c). 

Southern flounder. Southern flounder are in coastal habitats from North Carolina, through 

Florida and along the Gulf coast to northern Mexico. Spawning occurs offshore during the late 

fall and early winter. Eggs and sperm are randomly released into the water column for 

fertilization. After spawning, adults return to the estuaries and rivers. Larval flounder remain 

offshore in the plankton for 4 to 8 weeks. As they metamorphose into juveniles, currents carry 

the larvae into estuaries. Juvenile southern flounders begin migrating to up tidal rivers, where, 

according to some researchers, juvenile and young adults remain for the first 2 years 

(Patillo et al. 1997; Corps 2007; Hassan-Williams and Bonner 2009). 

Southern flounder are commercially harvested in Matagorda Bay (Corps 2007) and are also 

recreationally important in the region. There are commercial bag and possession limits, 

recreational bag limits, and harvested fish must exceed 14 in. in length (TPWD 2009f, i). 

Southern flounder were collected in the Colorado River during the 1975-1976 ichthyoplankton 

and nekton samples (NRC 1986) as well as during the 2007-2008 survey (ENSR 2008c). The 

species was also collected in the MCR during the 1994 employee tournament (STPNOC 2010a) 

but was not collected in the 2007-2008 survey (ENSR 2008b). 

Spotted seatrout. The spotted seatrout is an inshore demersal fish found from Massachusetts 

down to Florida and throughout the Gulf of Mexico to the Bay of Campeche, Mexico. They are 

most abundant from Florida to Texas. Eggs are either pelagic or demersal, depending on 

salinity. Larvae start out pelagic and become demersal after 4 to 7 days. Juveniles and adults 

remain demersal as they complete their life cycle, forming small schools, foraging in inshore 

waters. In Matagorda Bay, all of the life stages of spotted seatrout are common. The species is 

an opportunistic, visual carnivore that feeds in the upper portion of the water column and near 

the surface (Patillo et al. 1997). 

Spotted seatrout have been a commercially important species in Texas, but declining 

populations resulted in a closure of the fishery. Currently there is no commercial harvesting of 

them in Matagorda Bay (Patillo et al. 1997; Corps 2007). The species is part of the recreational 

fishery within the vicinity of STP, and the regulations state that only 10 fish are allowed per day, 

each between 15 and 25 in. in length (TPWD 2009l). Spotted seatrout were collected in the 

Colorado River during the 1975-1976 ichthyoplankton samples (NRC 1986) and 2007-2008 

survey of the river (ENSR 2008c). Spotted seatrout have also been collected in Matagorda Bay 

(Corps 2007). 

Striped mullet. Striped mullet are found worldwide in warm, tropical, sub-tropical, and 

temperate waters. They are an important forage fish for other aquatic and terrestrial predators. 

The species is a broadcast spawner, releasing eggs and sperm into the water column for 

fertilization in the coastal waters. The eggs and larvae remain offshore where they develop into 
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NUREG-1937 2-96 February 2011 

prejuveniles, and then enter the bays and estuaries to mature. In Matagorda Bay, all life stages 

of the striped mullet are abundant. Larvae are carnivorous, consuming planktonic material. 

Their diet changes from omnivores to herbivores as they develop as juveniles, and adults 

remain predominantly herbivores (Patillo et al. 1997; Corps 2007). 

Striped mullet are harvested commercially in Matagorda Bay, and are also recreationally 

important in the vicinity of STP (Corps 2007). There are no commercial or recreational limits for 

catching striped mullet however, from October through January fish may only be collected if 

they are less than 12 in. in length (TPWD 2009l, o). Stripped mullet have been collected in 

onsite drainages (NRC 1975; STPNOC 2010a) as well as in the MCR (ENSR 2008b). The 

species was also collected in the Colorado River during the 1975-1976 nekton samples 

(NRC 1986) and in the 2007-2008 survey (ENSR 2008c). 

Commercially and Recreationally Important Shellfish

Blue crab. Blue crabs are crustaceans (decapods) and are abundant throughout the Gulf of 

Mexico. During their life stages, they are found in various regions of the coastal waters. After 

female blue crabs mate, they migrate to higher salinity areas of the estuary (near tidal inlets or 

just offshore) where they lay their eggs. The female carries the eggs attached to the underside 

of her abdomen for about 2 weeks. Just prior to the eggs hatching, females move seaward and 

the eggs hatch offshore. Blue crab larvae pass through several larval stages in the marine 

plankton before moving back into the estuary with the surface plankton. Female blue crabs 

occur in the bays year round, but their population peaks in June and July. Male blue crabs 

remain in the lower salinity portions of the bays throughout their life. In Matagorda Bay, adults, 

spawning adults, and juvenile crabs are common, and the larvae are highly abundant. Larval 

crabs likely feed on plankton and zooplankton, whereas juveniles and adults are omnivores, 

scavengers, detritivores, predators, and cannibals that feed on a variety of plant and animal 

matter (Patillo et al. 1997; Corps 2007). 

Blue crabs are commercially important shellfish in Matagorda Bay, and while there are no bag 

or possession limits there are regulations on the size, number of traps that can be placed, and 

time of year for harvesting the crabs. The species is also important recreationally, and the 

regulations are similar to commercial harvesting (TPWD 2009f, i). Blue crabs were collected 

onsite in drainages (NRC 1975; STPNOC 2010a) and were one of the most common species 

collected in the 2007-2008 survey of the MCR (ENSR 2008b) and during the impingement 

sampling at the MCR’s CWIS (ENSR 2008b). They were collected in the Colorado River during 

the 1975-1976 nekton samples (NRC 1986) and during the 2007-2008 survey (ENSR 2008c). 

Blue crabs have also been collected in nekton samples in Matagorda Bay (Corps 2007). 

Eastern oyster. Eastern oysters are mollusk (bivalves) that are found throughout the estuarine 

coastal areas of the Gulf of Mexico. As adults, the oysters are sessile and can form reefs over 

time. In the spring, rising temperatures and chemical cues stimulate the release of sperm into 
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February 2011 2-97 NUREG-1937 

the water column by male oysters. Females then release their eggs into the water. The eggs 

are planktonic. Larval oysters remain as plankton in the water column for 2 or 3 weeks before 

settling onto a hard substrate and eventually transforming into adults. In Matagorda Bay, all life 

stages are common. While larvae consume plankton, juvenile (spat) and adults are suspension 

filter feeders, consuming plankton and zooplankton as they filter large quantities of brackish 

water (Patillo et al. 1997; Corps 2007). 

Eastern oysters are harvested commercially in Matagorda Bay. Open season for oysters is from 

sunrise to sunset during November through April, but there are no season limits for private 

leases with permits from TPWD. Commercial regulations are associated with the size, culling, 

collection method, and quantity. The species may also be collected recreationally in Texas 

from November through April, and there are limits associated with the size, collection tools, and 

quantity (TPWD 2009l, o). There are no reports of oysters in the Colorado River above the 

GIWW, but there are efforts to improve oyster reefs in Matagorda Bay (LCRA 2006; Corps 2007). 

Species with Designated Essential Fish Habitat 

EFH has been designated by the Gulf of Mexico Fishery Management Council in the Lower 

Colorado River, GIWW, and Matagorda Bay. Below is a discussion of the four fish and three 

shellfish species that are protected as part of this designation. Further information can be found 

in the EFH Assessment included in Appendix F in support of a NRC/Corps joint consultation 

with the National Marine Fisheries Service (NMFS) pursuant to the Magnuson-Stevens Fishery 

Conservation and Management Act. 

EFH is designated by life stage for each species as follows. Coastal migratory pelagic fish 

include juvenile king mackerel (Scomberomorus cavalla) and all life stages (eggs, larvae, 

juveniles, adults) of the Spanish mackerel (S. maculatus). The grey (mangrove) snapper 

(Lutjanus griseus) is the only species of reef fish in the vicinity, and the listing is for all life 

stages of the gray snapper. All life stages of red drum are listed in the vicinity. The shrimp 

species include all life stages for the brown shrimp, pink shrimp, and white shrimp. Finally, EFH 

for the vicinity includes all life stages of the Western Gulf stone crab (Menippe adina). Menippe 

adina has been recognized as a new species, distinct from M. mercenaria, and is the species 

most common in the Gulf along the Texas coastline (Guillory et al. 1995). 

King mackerel are highly migratory and are aggressive predators that specialize in feeding on 

other fishes. Common prey includes herrings, including menhaden and sardines. King 

mackerel can live to at least 14 years, although most die earlier. Females grow larger than 

males and spawn in their third or fourth year of life, with spawning occurring in the summer 

months (TSFGW 2005). Adults are primarily found offshore, but juveniles occasionally frequent 

estuarine waters for foraging (GMFMC 2004). Although no king mackerel have been observed 

during sampling studies, juvenile king mackerel are likely to occur in Matagorda Bay, GIWW, 

and the Colorado River. 
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NUREG-1937 2-98 February 2011 

Adult Spanish mackerel forage in estuarine and marine nearshore pelagic waters, and eggs and 

juveniles also occur nearshore marine surface (eggs) and pelagic (juveniles) waters (GMFMC 

2004). Spawning takes place from late spring to late summer at depths of less than 50 m along 

the Texas inner continental shelf (De Vries et al. 1989). Although no Spanish mackerel have 

been observed during sampling studies, adults may occur in the Colorado River, the GIWW, 

and Matagorda Bay whereas eggs, larvae, and juveniles are most likely to occur in the GIWW 

and Matagorda Bay. 

For estuarine habitats associated with the Colorado River, GIWW, and Matagorda Bay, larval, 

juvenile, and adult life stages of gray snapper, or mangrove snapper, are likely present because 

this species occupies primarily inshore habitats (GMFMC 2004). Eggs are found primarily in 

marine waters as part of the plankton community. Juveniles and adults are found in inshore 

marine and estuarine habitats with SAV or near mangroves, where they forage on small fish 

and crustaceans (Croker 1962). Gray snapper were collected within the first 3 mi of the 

Colorado River and the GIWW during the 2007-2008 sampling events (ENSR 2008c). Adults 

and juveniles occur in potential foraging habitat within the Colorado River, GIWW, and 

Matagorda Bay. 

Red drum larvae and juveniles spend most of their time in estuarine soft bottom, sand/shell, and 

SAV habitats actively feeding on mysids, crustaceans, and fish. Adults spend some time near 

inshore SAV, sandy or hard-bottom foraging habitats, but are predominantly found offshore 

where spawning activities occur (GMFMC 2004). Red drum move to deep offshore waters to 

spawn in the fall and then return to nearshore coastal and estuarine habitats where they spend 

most of their life cycle (FFWCC 2007). Tidal currents move larvae to nearshore habitats, where 

they grow rapidly as juveniles during the first 2 years, and associate with seagrass habitats with 

little wave action (Buckley 1984). Red drum were collected in the Colorado River in 2007-2008 

(ENSR 2008b, c) and are known to be in Matagorda Bay and the GIWW. Red drum was 

collected with all types of sampling gear, indicating that the species was well distributed in the 

river. With the exception of spawning adults, all life stages of red drum may occur in the 

Colorado River, GIWW, and Matagorda Bay. 

In the vicinity of STP, EFH is designated for three shrimp species: pink, white, and brown 

shrimp. All of these species migrate from offshore pelagic environment as larvae to inhabit 

grassy, estuarine habitats as juveniles (GMFMC 2004). Adult shrimp spawn in offshore waters 

between spring and early summer for brown shrimp, and from spring to fall for white shrimp 

(FWS 1983), and throughout the year for pink shrimp (TPWD 2002). White shrimp larvae may 

also be found in the nearshore marine water column, but prefer estuarine habitats, and migrate 

further upstream in estuarine waters than brown shrimp (GMFMC 2004). White and brown 

shrimp prefer soft bottom, shallow estuarine areas (FWS 1983). Post-larval and juvenile pink 

shrimp are closely associated with seagrass beds in estuarine waters (TPWD 2002). Juvenile 

and adult shrimp of all three species are omnivorous with diets that vary depending on available 
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February 2011 2-99 NUREG-1937 

food sources within the occupied habitat which is preferably soft bottom, shallow estuarine 

areas (FWS 1983). Both white and brown shrimp were collected in sampling studies all along 

the Colorado River in 1975-1976, 1983-1984 and 2007-2008 (ENSR 2008b, c). Larval and 

juvenile white and brown shrimp are likely to occur in the Colorado River, GIWW, and 

Matagorda Bay. Pink shrimp are often difficult to distinguish from brown shrimp, and pink and 

brown shrimp are usually reported together in information about the shrimping fishery in Texas 

coastal waters (Patillo et al. 1997); this is likely the reason pink shrimp are not reported in the 

Colorado River studies. The three shrimp species combined represent the greatest commercial 

harvest for Matagorda Bay, exceeding the catches for finfish and other shellfish (TPWD 2002; 

Corps 2007). 

The Gulf stone crab occupies estuarine and marine SAV, sand/shell, and hard-bottom habitats 

as eggs, larvae, and juveniles (GMFMC 2004). Adults prefer a diet of oysters, are typically 

found near oyster reefs or other hard-bottom substrate, and are both intertidal and subtidal 

(Wilber 1989). The stone crab fishery is managed by a Gulf of Mexico Fishery Management 

Plan to regulate this renewable fishery with harvest only of claws greater than 2.75 in. long. 

Florida stone crabs require high salinities for juvenile growth, but the Western Gulf stone crab 

tolerates estuarine waters (GMFMC 2004). All life stages of Western Gulf stone crab may occur 

in the GIWW and Matagorda Bay, but none of the surveys conducted in the vicinity of STP since 

the 1970s has identified this species. 

Ecologically Important Species 

Several ecologically important species or taxa occur in the onsite water bodies and the 

Colorado River near the STP site. Ecologically important species are those that are important 

to the structure or function of the aquatic system (e.g., forage fish for many other species), or 

they provide critical links in the food web for Gulf of Mexico estuarine and marine ecosystems. 

These species may also be indicators of habitat quality in the system. As discussed in Section 

2.4.2.1, there have been few surveys of on-site water bodies and the Colorado River that have 

included characterization of the primary producers and species representative of the lower parts 

of the food chain (e.g., surveys of algae and macroinvertebrates). However, the surveys of 

aquatic communities indicate that there is an abundant and diverse aquatic community in onsite 

water bodies and the river that could only exist if the primary producers and species 

representative of the lower parts of the food chain were also abundant and diverse. 

In addition to primary producers, forage fish and invertebrates play ecologically important roles 

in the food web. Some of these include commercially important species and species with 

designated EFH. Bay anchovy is a commercially important species (discussed above) that is 

also an important forage fish. Anchovies are consumed by other fish found in the Colorado 

River such as Atlantic croaker, blue catfish, ladyfish, red drum, sand seatrout, spotted seatrout, 

and southern flounder (Patillo et al. 1997). Other examples of fish (particularly early life stages) 

and invertebrates that are important prey for other fish and are also commercially important 
Affected Environment 

NUREG-1937 2-100 February 2011 

include Altantic croaker, striped mullet, and blue crab (Patillo et al. 1997). Brown, pink, and 

white shrimp are species with designated EFH (discussed above) that are also important food 

sources for a number of other fish, including ladyfish, hardhead catfish, red drum, black drum, 

sand seatrout, spotted seatrout, and southern flounder (Patillo et al. 1997). 

Other commercially important species are used as indicators of habitat quality. Because bay 

anchovy can adapt quickly to pollution stress, shifts in their population may be an indicator of 

poor deteriorating water quality. Atlantic croaker, Gulf menhaden, and Eastern oyster are 

indicator species for environmental stress, often used in toxicity studies with heavy metals and 

organic compounds, and are target species for NOAA’s National Status and Trends Program 

(Patillo et al. 1997). Gulf menhaden are frequently involved in fish kills and have been 

monitored as an indicator of hypoxia (low dissolved oxygen) in the Gulf. Because the 

distribution and abundance of oysters is particularly influenced by salinity, this species is one of 

the key organisms being monitored as part of the recovery of Matagorda Bay and in 

understanding freshwater inflow into the bay since the completion of the Colorado River 

diversion project (Patillo et al. 1997; LCRA 2006). 

Grass shrimp are ecologically important as prey for a number of aquatic and terrestrial species 

as well as for their role in breaking down detritus in estuarine and tidal rivers (Patillo et al. 1997). 

The species was one of the most frequently collected invertebrates in the 2007-2008 Colorado 

River survey and in the MCR (ENSR 2008b, c), and all life stages are considered highly 

abundant in Matagorda Bay (Patillo et al. 1997). These shrimp are not commercially important 

but are likely collected as bait for recreational fishing. Grass shrimp are most often found in 

shallow waters, often in vegetated areas. Juveniles and adults can tolerate salinities from 0 to 

55 ppt, but it is unclear how salinity affects early life stages and growth. The spawning season 

is from February to October. Grass shrimp are opportunistic, omnivorous feeders, including 

consumption of large detrital particles, and provide food sources for organisms in a variety of 

trophic levels (Patillo et al. 1997). 

Ecologically important species for the onsite water bodies (e.g., the MDC and MCR) include 

foraging fish and invertebrates. Largemouth bass, bluegill, and mosquitofish were the most 

common species collected in the MDC (ENSR 2007c). These fish are tolerant of environmental 

changes, and common in inshore waters in Texas. All of these species are carnivores, feeding 

primarily on macroinvertebrates, and as adults may also feed on other smaller fish (HassanWilliams and Bonner 2009). The most common fish in the MCR were the threadfin shad, inland 

silverside, and rough silverside (ENSR 2008b). These fish are probably the main prey for such 

top carnivore species found in the MCR as the blue and channel catfish (Patillo et al. 1997). 

Threadfin shad are planktivore filter feeders while inland silverside are carnivores, feeding 

primarily on macroinvertebrates (Patillo et al. 1997; Hassan-Williams and Bonner 2009). 
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February 2011 2-101 NUREG-1937 

Federally and State-Listed Species 

All the Federally listed aquatic species in Matagorda County are those listed by NMFS and 

include the endangered smalltooth sawfish (Pristis pectinata), leatherback sea turtle 

(Dermochelys coriacea), hawksbill sea turtle (Eretmochelys imbricata), and Kemp’s ridley sea 

turtle (Lepidochelys kempii). The threatened species include the loggerhead sea turtle 

(Caretta caretta) and green sea turtle (Chelonia mydas). In addition, NMFS lists several 

endangered whale species that could be found off the Texas coastline in deeper offshore 

waters, including blue whale (Balaenoptera musculus), finback whale (B. physalus), sei whale 

(B. borealis), humpback whale (Megaptera novaeangliae), and sperm whale (Physeter 

macrocephalus). Because the whale species are not found in Matagorda Bay, the GIWW, or 

the Colorado River, they are not included in the Biological Assessment (BA) (in Appendix F). 

The only State-listed endangered species in Matagorda County is the West Indian manatee 

(Trichechus manatus). While the West Indian manatee is Federally listed as endangered and 

occurring in Texas, it is not listed as occurring in Matagorda County. The State-listed 

threatened species in Matagorda County include a fish, the blue sucker (Cycleptus elongates), 

and two freshwater mussels, the smooth pimpleback (Quadrula houstonensis) and the Texas 

fawnsfoot (Truncilla macrodon). TPWD has identified rare and protected species in the county, 

including American eel (Anguilla rostrata), Gulf Coast clubtail (dragonfly) (Gomphus modestus), 

and the freshwater mussels, creeper (squawfoot) (Strophitus undulatus) and pistolgrip 

(Tritogonia verrucosa) (TPWD 2009i). 

In correspondence with the TPWD, none of these aquatic species were found within 6 mi of the 

STP site (STPNOC 2010a; TPWD 2009a, j). The Federally listed sea turtle species may be 

found in Matagorda Bay and the navigational shipping channels at Port Freeport. The other 

Federally listed species are not likely to be found within the bay or shipping channels. No 

identified threatened and endangered aquatic species are located along the Hillje transmission 

line corridor (STPNOC 2010a; TPWD 2009j). 

Federally Listed Species

Smalltooth sawfish was listed by NMFS as endangered on April 1, 2003 (68 FR 15674), and 

they were once prevalent throughout Florida and were commonly encountered from Texas to 

North Carolina. The current range of this species is now restricted to peninsular Florida, 

therefore, the smalltooth sawfish is not included in the BA (in Appendix F). NMFS states that 

the primary reason for the decline of the species is bycatch (especially in gill nets) in various 

commercial and recreational fisheries. Loss of habitat is cited as another reason for the decline 

of the species, especially the mangrove forests that are important nursery areas for juvenile 

sawfish. Sawfish inhabit shallow waters close to shore with muddy or sandy bottoms, often in 

mangroves. They also occur in sheltered bays, on shallow banks, and in estuaries or river 

mouths, occasionally traveling inland in large river systems (NMFS 2009b; Corps 2008). There 
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NUREG-1937 2-102 February 2011 

have only been three records of sawfish reported in the Matagorda Bay region in the last 

20 years: Carancahua Bay (Matagorda Bay) in 1979; in the Gulf of Mexico off Aransas Bay in 

1984; and an unverified report in Lower Laguna Madre (Baffin Bay) in 2003. There are no 

current or short-term recovery efforts identified for the species in the region or within Texas 

(TPWD 2009n). 

Loggerhead sea turtles are distributed widely in tropical and subtropical seas, in the Atlantic 

Ocean from Nova Scotia to Argentina, Gulf of Mexico, Mediterranean Sea, and Indian and 

Pacific oceans (although they are rare in the eastern and central Pacific). They nest all along 

the Atlantic coast from Florida to as far north as New Jersey, but they nest sporadically along 

the Gulf coast, including Texas. The population of loggerheads in Texas has been declining as 

has the world-wide population. Loggerheads are the most abundant sea turtle in Texas marine 

waters, preferring shallow inner continental shelf waters and occurring very infrequently in the 

bays. They are often seen around offshore oil rig platforms, reefs, and jetties. Loggerheads are 

probably present year-round but they are most often noticed in the spring when the Portuguese 

man-of-war (Physalia physalis) (one of their preferred food choices) is abundant. Loggerheads 

constitute a major portion of the dead or moribund turtles that are washed ashore (stranded) 

each year on the Texas coast. A large proportion of these deaths are the result of drowning 

from accidental capture by shrimp trawlers. Nests have been confirmed along the Texas 

coastline, mostly to the south in the vicinity of Padre Island (NMFS and FWS 2007a, 2008; 

TPWD 2009k; Corps 2007, 2008). This species does occur in the study area. To the 

northwest, eight loggerheads were caught in Freeport Harbor from 1995 to 2000, one 

loggerhead was captured by a relocation trawler in 2002, and one was killed during dredging 

operations of the entrance/jetty channel to Freeport Harbor in 2006 (Corps 2008). To the 

southeast, a loggerhead turtle was killed in 1996 during dredging operations in the entrance 

channel of the Matagorda Ship Channel, and two loggerheads were taken in the entrance 

channel of the ship channel during dredging operations in 2006 (Corps 2007). The loggerhead 

sea turtle is further discussed in the BA in Appendix F. 

The green sea turtle is a circumglobal species found throughout tropical and subtropical waters. 

Their distribution in U.S. Atlantic waters is around the U.S. Virgin Islands, Puerto Rico, and 

continental United States from Massachusetts to Texas. The green turtle in Texas inhabits 

shallow bays and estuaries where it can graze on various marine grasses, but juveniles are 

often found in bays without seagrasses. The greatest cause for the decline of the species 

worldwide is commercial harvest for eggs and food, but the turtles are also threatened by 

incidental catch during commercial shrimp trawling (TPWD 2009i). Major nesting activity for 

these turtles occurs outside of U.S. waters, on Ascension Island, Aves Island (Venezuela), 

Costa Rica, and in Surinam. Nesting within the U.S. is primarily in Florida, with some nesting 

areas in Georgia, North Carolina, and Texas (NMFS and FWS 1991; Hirth 1997). Green turtle 

nests are rare in Texas and have primarily been located south at Padre Island National 

Seashore. No green turtle nests have been recorded around Matagorda Bay. Juvenile and 
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February 2011 2-103 NUREG-1937 

adult green turtles are in the study area (NMFS and FWS 1991, 2007b; TPWD 2009i; Corps 

2007, 2008). A study by Texas A&M University at Galveston (TAMUG) in 1996-1997 (Williams 

and Renaud 1998) found that four of the green turtles fitted with radio transmitters spent time in 

Lavaca Bay, western Matagorda Bay, and Powderhorn Bayou. A green turtle was recorded 

swimming in the Matagorda Ship Channel and one was taken during dredging operations at the 

same location in 2004 (Williams and Renaud 1998; Corps 2007). In 2006, two green turtles 

were killed during maintenance dredging of the entrance and jetty channels of the Freeport 

Harbor Project (Corps 2008). The Atlantic green sea turtle is further discussed in the BA in 

Appendix F. 

The leatherback sea turtle is found in the Atlantic, Pacific, and Indian oceans; as far north as 

British Columbia, Newfoundland, Great Britain and Norway; and as far south as Australia, Cape 

of Good Hope, and Argentina. This species is mainly pelagic, occupying the open ocean, and 

seldom approaches land except for nesting. Foraging turtles have been observed in bays and 

estuaries following large concentrations of jellyfish (TPWD 2009i). Leatherbacks nest primarily 

in tropical regions. The largest nesting assemblages in the Atlantic and Caribbean occur in the 

U.S. Virgin Islands, Puerto Rico, and Florida. There have been no recorded nests in Texas 

since the 1930s on Padre Island. There have been occasional reports of leatherbacks feeding 

on jellyfish off Port Aransas and Brownsville. No leatherback sea turtles have been taken by 

dredging activities in Texas. One leatherback was caught in 2003 by a relocation trawler in a 

shipping channel approximately 1.5 mi north of Aransas Pass (NMFS and FWS 1992a, 2007c; 

TPWD 2009k; Corps 2007, 2008). This species is unlikely to occur in the vicinity of the STP 

site. The leatherback sea turtle is further discussed in the BA in Appendix F. 

The hawksbill sea turtle is probably the most tropical of all the sea turtles, found throughout the 

tropical and subtropical seas of the Atlantic, Pacific, and Indian oceans and rarely in temperate 

regions. Hawksbill sea turtles are widely distributed in the Caribbean and western Atlantic, and 

all life stages have been found regularly off southern Florida and in the northern Gulf (especially 

Texas). The first and only hawksbill nest recorded in Texas was in 1998 at Padre Island 

National Seashore. Outside of Florida, Texas is the only state where hawksbills are 

encountered with any regularity. Most of these sightings are around stone jetties and have 

been post-hatchling and juvenile turtles. These small turtles have probably traveled north from 

nesting beaches in Mexico (NMFS and FWS 1993, 2007d; TPWD 2009k; Corps 2007, 2008). 

This species potentially occurs in the study area. The hawksbill sea turtle is further discussed in 

the BA in Appendix F. 

The Kemp’s ridley sea turtles distribution is primarily in the Gulf of Mexico and the Atlantic 

seaboard. It is the smallest marine sea turtle in the world. The turtles inhabit shallow coastal 

and estuarine waters, usually over sand or mud bottoms. Kemp’s ridleys are found in small 

numbers in Texas and are probably in transit between crustacean-rich feeding areas in the 

northern Gulf and breeding grounds in Mexico. The nesting area for Kemp’s ridleys is almost 
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NUREG-1937 2-104 February 2011 

entirely on an 11-mi stretch of coastline near Rancho Nuevo, Tamaulipas, Mexico, 

approximately 190 mi south of the Rio Grande. The species has nested sporadically in Texas in 

the last 50 years, with reports increasing over the last 12 years from 4 nests in 1995 to 102 

nests in 2006, with a majority of the nests at Padre Island National Seashore. There was one 

nest recorded on Matagorda Peninsula in 2002, and four on Matagorda Island in 2004. The 

increase in nests is related to the success of breeding programs in Texas. A study by TAMUG 

in 1996 found that seven of the Kemp’s ridley turtles fitted with radio transmitters spent most of 

their time within 4 mi of the western shoreline of Matagorda Bay, but also swam to Lavaca Bay, 

Carancahua Bay, Tres Palacios Bay, and Powderhorn Bayou (Williams and Renaud 1998). 

Two Kemp’s ridleys were taken at the entrance of the Matagorda Ship Channel in 2006 during 

dredging operations (NMFS and FWS 1992b, 2007e; TPWD 2009k; Corps 2007, 2008; Williams 

and Renaud 1998). Of all the turtles, Kemp’s ridleys are likely to be the most common in the 

study area. The Kemp’s ridley sea turtle is further discussed in the BA in Appendix F. 

The blue whale is listed as endangered by NMFS under the ESA. This species inhabits and 

feeds in both coastal and pelagic environments, and its distribution is thought to be associated 

with its food requirements. Populations of blue whales move toward the North and South Poles 

in the spring to feed in waters with high zooplankton production during summer months. In the 

fall, the whales move toward the subtropics, presumably to reduce energy expenditure while 

fasting and reproducing. The blue whale is considered only an occasional visitor in the 

U.S. Atlantic waters. While the actual southern limit of the range of the blue whale is unknown, 

the western North Atlantic is thought to be still within its feeding range. Some records have 

suggested an occurrence of this species in waters near Florida and in the Gulf of Mexico. 

However, the blue whale is not expected to occur in the study area and, therefore, is not 

included in the BA (Corps 2007, 2008). 

The finback or fin whale is listed as endangered by NMFS under the ESA. This species is found 

offshore and the whales tend to be nomadic. Finback whales follow the same migration for 

feeding and reproduction as the blue whales. The finback whale is not expected to occur in the 

study area and, therefore, is not included in the BA (Corps 2007, 2008). 

The sei whale is listed as endangered by NMFS under the ESA. This species inhabits, breeds, 

and feeds in open oceans, and is usually restricted to more temperate waters. Sei whales 

migrate several thousand miles to the equator in the fall. Their feeding ranges and reproduction 

are similar to those of the blue whales. They are also known to occur near Cuba, the Virgin 

Islands and infrequently in U.S. waters. In the vicinity of U.S. waters, sei whales are grouped 

into four stocks: East North Pacific, Hawaii, Nova Scotia, and Western North Atlantic stocks. 

There are not enough data to determine trends in the recovery of the species. However, sei 

whales continue to be taken through unauthorized hunting and incidental ship strikes and 

gillnetting bycatch. Sei whales are not expected to occur in the study area and, therefore, are 

not included in the BA (Corps 2007, 2008). 
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February 2011 2-105 NUREG-1937 

The humpback whale is listed as endangered throughout its range and is considered “depleted” 

under the Marine Mammal Protection Act. The humpback whale is found worldwide in all ocean 

basins, but this species is less common in Arctic waters. Humpback whales are generally 

considered to inhabit waters over continental shelves, along their edges and around some 

oceanic islands. These whales are seasonal migrants and are found in temperate and tropical 

waters of both hemispheres during the winter breeding season. During the summer feeding 

season, most humpbacks occur in higher latitude waters with high biological productivity. In the 

vicinity of U.S. waters, there are currently four recognized stocks (based on geographically 

distinct winter ranges) of humpback whales: Gulf of Maine, the eastern North Pacific, the 

central North Pacific, and the western North Pacific stocks. The worldwide population of 

humpback whales is thought to have been greater than 125,000 individuals prior to commercial 

whaling activities. The U.S. population of humpbacks is currently estimated to be less than 

7000 whales. Recovery plans for the species are focused on maintaining and enchancing 

habitats, identifying and reducing direct human impact, monitoring and updating of data on the 

species, and enhancing coordination and cooperation between recovery program units across 

the globe. The only known occurrence of humpbacks in Texas waters was in 1992 along the 

Bolivar Jetty near Galveston. The humpback whale is not expected to occur in the study area 

and, therefore, is not included in the BA (Corps 2007, 2008). 

The sperm whale is listed as endangered by NMFS under the ESA. Overexploitation from 

commercial whaling during the past two centuries is thought to be the reason for the decline of 

the species. Sperm whales are found throughout the world’s oceans in deep waters. They tend 

to inhabit areas with water depths exceeding 1900 ft, and are uncommon in waters less than 

985 ft deep. Sperm whale migrations are not as predictable or well understood as the 

humpback whales. Their distribution appears to be dependent on their food source and suitable 

conditions for breeding and varies with the sex and age composition of the group. Those 

whales in the oceans in mid-latitudes tend to migrate north and south depending on the seasons 

(whales move poleward in the summer), while the whales in tropical and temperate areas do not 

have an obvious seasonal migration. The sperm whale is not expected to occur in the study 

area and, therefore, is not included in the BA (Corps 2007, 2008). 

State-listed Species

The West Indian manatee is listed by TPWD as an endangered species in Matagorda County. 

FWS lists the species in all the counties up the coast of Texas to Calhoun County, just south of 

Matagorda County. This aquatic mammal inhabits brackish bays, large rivers, and saltwater 

systems. Its diet consists of available submergent, emergent, and floating vegetation. The 

manatee is more commonly found in the warmer waters off of coastal Mexico, the West Indies, 

and Caribbean to northern South America. In the U.S., manatees are primarily found in Florida. 

Sitings of manatees in Texas are extremely rare and are likely to be individuals that are 

migrating or wandering up from Mexican waters. Historically, manatees were found in Cow 
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NUREG-1937 2-106 February 2011 

Bayou, Sabine Lake, Capano Bay, the Bolivar Peninsula, and the mouth of the Rio Grande. In 

May 2005, a live manatee was photographed in the Laguna Madre near Port Mansfield, south of 

Corpus Christi. The Corps determined that manatees were unlikely to be found in the vicinity of 

the Matagorda Ship Channel and Port Freeport (Corps 2007, 2008), and therefore, they are 

unlikely to be found within the vicinity of STP. 

The blue sucker, State listed as threatened, is described as a sucker that is dark olive or blueblack on its back and sides and white on the underside. The species is thought to reach up to a 

length of 40 in., with a small head, small mouth and overhung snout typical of sucker species 

(Thomas et al. 2007). The species is reported to be in the major rivers of Texas, usually in the 

channels and free-flowing pools with moderate currents and exposed bedrock, hard clay, sand 

or gravel substrates. Its spawning areas are typically upstream in riffles (TPWD 2009h). There 

are no reports of the blue sucker in the Colorado River in the vicinity of STP, although the 

habitat for the fish exists in the region. 

TWPD categorized the American eel as rare and protected in Matagorda County. American eel 

is found in rivers and streams along in all the states in the Gulf Coast and along the Atlantic. It 

is a catadromous species, meaning that eels spend most of their lives in freshwater and travel 

to the western Atlantic Ocean (Sargasso Sea) to spawn. The larvae are ribbon-shaped and are 

carried by currents back to rivers. Larvae then metamorphose into “glass eels” and move back 

upstream into rivers to mature into adults. The adults can grow up to 4.3 ft. in length, and have 

a slightly compressed, snake-like body (Thomas et al. 2007). The number of eels reported in 

Texas has been diminishing since the 1970s. LCRA has reported finding an American eel as 

far up the Colorado River as Altair, Texas, where the eel had to traverse over dams. However, 

in studies over the last 30 years, TPWD has only collected seven eels in the bays sampled from 

Matagorda down to Corpus Christi (STPNOC 2010a). ENSR (2008b) reported collecting one 

adult eel (2.6 ft in length) during the impingement sampling in the MCR’s CWIS for Units 1 

and 2. 

Gulf Coast clubtail is a dragonfly that is reported in Matagorda County and categorized as rare 

and protected by TPWD. The early life stages of the clubtail are aquatic and are spent in 

medium-sized rivers with moderate gradients and streams with silty sand or rocky substrate. 

The adult clubtails are found to forage in trees along stream riparian areas (TPWD 2009h). 

There are no reports of clubtails in the surveys of water bodies around STP, although the 

habitat for these dragonflies exists in the region. 

Four freshwater mussels have been identified by TPWD as being found in Matagorda County 

(TPWD 2009h). While not much is known specifically about the life histories and distribution of 

these species, they are all known as uniod mussels and have a larval stage called a glochidium. 

For glochidia to mature to juvenile mussels, they must live as a parasite in the gill tissues of a 

host fish. An important component to the distribution of freshwater mussels in various water 

bodies is associated with the relationship between the mussels and the host fish (Howells et al. 
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February 2011 2-107 NUREG-1937 

1996). While the habitat exists around STP and in the drainages along the Hillje transmission 

corridor to support these freshwater mussel species, none of these organisms have been 

reported during surveys of the onsite water bodies at STP or in the reach of the Colorado River 

in the vicinity of the site (ENSR 2008a, b, c; STPNOC 2010a). Below is a discussion on what is 

known about the four species reported by TPWD in Matagorda County. 

Texas Parks and Wildlife Commission acted on November 5, 2009, to place 15 of the 

50 freshwater mussel species that have been identified in the state on the State threatened 

species list (TPWD 2009h; 35 Texas Register 249). The list includes the smooth pimpleback 

and Texas fawnsfoot that are reported for Matagorda County. Smooth pimpleback is reported in 

the Colorado and Brazos River drainage basin. It prefers substrates that are mud, sand and fine 

gravel in very slow to moderate flow rates. It is unclear if the mussels have glochidia and the 

host species for the glochidia is unknown (Howells et al. 1996; TPWD 2009i). Surveys from 

1980 to 2006 for the smooth pimpleback have noted steep declines in the number of extant 

populations in both river drainages (TPWD 2009h). Texas fawnsfoot is reported in the Colorado, 

Trinity and Brazos River drainages. However, there is no information about its preferred habitat, 

glochidia production or fish host species (Howells et al. 1996; TPWD 2009i). 

Additionally, TPWD categorized two other freshwater mussels, creeper and pistolgrip, as rare 

and protected in Matagorda County. Creeper or squawfoot occurs in drainages from the 

Guadalupe River to the north and east, including the Colorado River drainage. The creeper has 

been found in a variety of habitats, including substrates varying from silt to gravel, shallow to 

fairly deep water, and flow rates from still to rather rapid. The species does appear to be 

sensitive to drought conditions. While the creeper is known to produce glochidia and several fish 

hosts have been identified (e.g., largemouth bass, creek chub (Semotilus astromaculatus), plains 

killifish (Fundulus zebrinus) and green sunfish), there is evidence that the species might be able 

to complete its life cycle without a host species (Howells et al. 1996). Pistolgrip occurs in 

drainages from the San Antonio River to the north and east, including the Colorado River 

drainage. Like the creeper, the pistolgrip has been reported in a variety of habitats. The species 

is known to produce glochidia but the fish host species is unknown. Historically, the pistolgrip 

has been important economically for the shell-button industry as well as a producer of high 

quality, freshwater pearl industry (Howells et al. 1996). 

Important Habitats 

As discussed in Section 2.4.1.3, the Mad Island WMA and Clive Runnells Family Mad Island 

Marsh Preserve are to the southwest of the STP site and are important habitats for aquatic 

organisms associated with Matagorda Bay and the Gulf of Mexico (Figure 2-21). The area 

consists of freshwater wetlands, estuarine intertidal marshes and intertidal flats, and supports 

early life stages of red drum, blue crab, shrimp, oysters, southern flounder and speckled 

seatrout (Cynoscion nebulosus) (TPWD 2007; TNC 2009). The flow of water from Little 

Robbins Slough in the vicinity of STP provides freshwater into these wetlands, and the mixture 
Affected Environment 

NUREG-1937 2-108 February 2011 

of freshwater and estuarine waters is essential to the productivity of the aquatic community 

(NRC 1975, 1986; TPWD 2007; TNC 2009). Additionally, there is designated EFH in the vicinity 

of STP. The Colorado River extending up to the bridge at FM 521, GIWW and Matagorda Bay 

are within Ecoregion 5 of the designated EFH by the Gulf of Mexico Fishery Management 

Council’s FMP (GMFMC 2004). Ecoregion 5 extends from Freeport, Texas to the Mexican 

border. FMPs applying to waters identified for the Colorado River, GIWW and Matagorda Bay 

within the vicinity of STP include coastal migratory pelagic, reef fish, red drum, shrimp, and 

stone crab (GMFMC 2004). There are no habitat areas of particular concern for the Colorado 

River (GMFMC 2004). Further discussion can be found in the EFH Assessment in Appendix F. 

2.4.2.4 Aquatic Monitoring 

STPNOC does not conduct any routine monitoring of the aquatic resources on the site. 

Regulatory agencies have not required ecological monitoring of the STP site, the operation of 

the RMPF on the Colorado River, or the associated transmission corridors since the period of 

reservoir filling (mid-1980s), and there is no ongoing monitoring of aquatic resources on the site. 

There have been studies in the past associated with licensing of the existing STP Units 1 and 2, 

and impingement and entrainment impacts at the RMPF at both high- and low-river flow 

conditions were estimated (NRC 1975, 1986). Several studies were conducted in preparation 

for the combined license (COL) application for proposed Units 3 and 4. 

The recent studies have included a rapid bioassessment of onsite drainages ditch system 

(ENSR 2007c) and aquatic assessments of the MCR and the CWIS for existing Units 1 and 2 

(ENSR 2008b) and the Colorado River (ENSR 2008c). The onsite drainage ditch system was 

characterized using a modified version of EPA’s standardized Rapid Bioassessment Protocols, 

including fish surveys and water quality sampling (physiochemical analyses). Results were 

used to evaluate potential aquatic ecology impacts of building activities that would eliminate 

some existing ditches, change the flow of water, especially during rain events, into the 

remaining and expanded drainage ditch system (ENSR 2007c). 

From May 2007 through April 2008, the aquatic ecology of the MCR was characterized, and an 

evaluation of impingement and entrainment at the CWIS for existing Units 1 and 2 on the MCR 

was conducted. This was the first effort to characterize the fish and shellfish community in the 

MCR since it was constructed (other than a catch-and release fishing tournament for employees 

in 1994) (STPNOC 2010a). Four sampling events were conducted across four sampling 

regions in the MCR to collect fish and shellfish using a variety of sampling gears. The 

impingement and entrainment studies at the CWIS were conducted over a 24-hr period, twice 

per month from May through September and once per month from October through April. 

Results of these studies were used to characterize the aquatic resources in the MCR and to 

“establish relationships between the presence of aquatic organisms and the intake design and 

operation parameters” of existing STP Units 1 and 2 for evaluating potential impacts with the 

proposed new units (ENSR 2008b). 
Affected Environment 

February 2011 2-109 NUREG-1937 

From June 2007 through May 2008, the aquatic ecology of the Colorado River was 

characterized for an approximately 9-mi stretch extending from the GIWW north to the FM521 

bridge. The Lower Colorado River in the vicinity of the site has not been characterized except 

for studies associated with the STP site. These studies, associated with licensing of existing 

STP Units 1 and 2, were conducted in 1974, 1976, 1983 and 1984. This study was the first one 

to be conducted since the Corps completed the diversion channel of the Colorado River in 1993, 

diverting the flow of the river into Matagorda Bay rather than flowing directly into the Gulf. 

Results of the study were used to compare the aquatic communities, current flow, and salinity 

patterns to those prior to the 1992 diversion channel construction (ENSR 2008c). 

There are no known aquatic surveys of the transmission corridors for existing STP Units 1 

and 2. Only a 20-mi section of the Hillje transmission line would be disturbed by construction 

activities for proposed Units 3 and 4. Maintenance and operation practices for the transmission 

lines are consistent with state regulations for protection of aquatic life (STPNOC 2010a). 

2.5 Socioeconomics 

This section describes the socioeconomic baseline of the proposed site. It describes the 

characteristics of the 50-mi region surrounding the STP site, including population demographics, 

density, and use that form the basis for assessing the potential social and economic impacts 

from building and operating the proposed two new nuclear units. These impacts are for the 

region(a) surrounding the proposed site. This discussion emphasizes the socioeconomic 

characteristics of Matagorda, Brazoria, Calhoun, and Jackson Counties, although it considers 

the entire region within a 50-mi radius of the proposed site. STPNOC assumed that the 

residential distribution of the proposed Units 3 and 4 construction and operational workforces 

would resemble the residential distribution of STPNOC’s current workforce. As of January 

2007, approximately 83 percent of the STP employees reside within two counties—Matagorda 

(60.7 percent) and Brazoria (22.4 percent). The remaining 17 percent are distributed across at 

least 18 other counties, with less than 5 percent of the employees per county (Table 2-16). 

STPNOC also assumed that most of the socioeconomic impacts would occur within Matagorda 

and Brazoria Counties. The review team has also examined the possibility that significant 

numbers of workers (numbering in the hundreds during the peak building period) may choose to 

live in Wharton, Fort Bend, Calhoun, Jackson, and Victoria Counties. (Lavaca County and 

Colorado County are within 50 mi, but currently have almost no STP workers and are at a 

somewhat greater distance than the other counties mentioned.) In Wharton, Fort Bend, and 

 

(a) For the purposes of this EIS, the relevant region is limited to that area necessary to include social and 

economic base data for (1) the county in which the proposed plant would be located and (2) those 

specific portions of surrounding counties and urbanized areas (generally up to 50 mi from the station 

site) from which the construction/operations work force would be principally drawn, or that would 

receive stresses to community services by a change in the residence of construction/operations 

workers. 
Affected Environment 

NUREG-1937 2-110 February 2011 

Victoria Counties, the existing populations are relatively large and the STP plant-related 

population is small and not as noticeable, so significant socioeconomic impacts are unlikely. 

Calhoun and Jackson Counties are both close to the STP site and lightly populated. Impacts 

are more likely there. Most of the data and analysis in this section will be concerned with a 

socioeconomic impact area containing four counties: Matagorda, Brazoria, Calhoun, and 

Jackson. The scope of the review of community characteristics is guided by the magnitude and 

nature of the expected impacts of building, maintaining, and operating the proposed project and 

by those site-specific community characteristics that can be expected to be affected by these 

impacts. 

Table 2-16. Distribution of STP Employees, January 2007 

County

Percent of Total 

Number of Employees

Cumulative 

Percent

County 

Population, 2000

Matagorda 60.7% 60.7% 37,957 

Brazoria 22.4% 83.2% 241,767 

Wharton 4.5% 87.6% 41,188 

Fort Bend 4.1% 91.7% 354,452 

OTHER 2.3% 94.0% N/A 

Calhoun 1.6% 95.6% 20,647 

Jackson 1.3% 96.9% 14,391 

Victoria 1.2% 98.1% 84,088 

Harris 0.8% 98.9% 3,400,578 

Aransas less than 0.1% 99.0% 22,497 

Austin less than 0.1% 99.2% 23,590 

Fayette less than 0.1% 99.3% 21,804 

Galveston less than 0.1% 99.5% 250,158 

Cass less than 0.1% 99.6% 30,438 

Colorado less than 0.1% 99.6% 20,390 

DeWitt less than 0.1% 99.7% 20,013 

Goliad less than 0.1% 99.8% 6928 

Hood less than 0.1% 99.9% 41,100 

Lavaca less than 0.1% 99.9% 19,210 

Williamson less than 0.1% 100.0% 249,967 

Total 100% – – 

Source: STPNOC 2010a 
Affected Environment 

February 2011 2-111 NUREG-1937 

The population data for the 50-mi area are based on the 2000 U.S. Census data and were 

estimated by the applicant with SECPOP 2000, a computer program that calculates population 

by emergency planning zone sectors (Sandia 2003).(a) In addition, the review team analyzed 

the economic, employment, and population trends for the region using additional U.S. Census 

data sets and population projections from the Texas State Data Center and Office of the State 

Demographer. 

The analytical area is a 50-mi circle centered on the proposed power block and includes all or a 

portion of nine counties in Texas. Table 2-17 identifies the counties and provides population 

information for each county within 50 mi of the STP site and Figure 2-24 shows the 50-mi 

analytical area. 

Table 2-17. Counties within 50 mi of the STP Site 

County 

Resident Population 

(Year 2000) 

Resident Population 

Estimate (January 1, 2007) 

Matagorda County 37,957 36,930 

Brazoria County 241,767 291,729 

Calhoun County 20,647 20,958 

Colorado County 20,390 21,925 

Fort Bend County 354,452 503,315 

Jackson County 14,391 14,598 

Lavaca County 19,210 19,382 

Victoria County 84,088 86,756 

Wharton County 41,188 42,262 

Source: Texas State Data Center 2007 

2.5.1 Demographics 

For a historical perspective, the 1940 population of Matagorda County was 20,066 people and 

over the next 60 years the population almost doubled to 37,957 in 2000. Brazoria County 

population in 1930 was only 23,114 people but continually rose in urban areas after 1940. 

Between 1970 and 1980 the population grew 57 percent. Calhoun County, the smallest of the 

four counties during the 1940s had a 1940 population of 5911 and despite being hit hard by a 

couple of hurricanes it grew to a population of 20,647 in 2000 with the help of new industry. 

Also increasing since the 1940s is the Hispanic population of the counties. Unlike the previous 

counties Jackson County’s population has remained fairly constant since World War II. The 

1950 population was 12,916 and fifty years later, the 2000 census reported a population of 

14,391. 

 

(a) Table G-1 in Appendix G provides population summary statistics for all counties within a 50-mi radius 

of the STP site that were used to assist in narrowing the scope to assess socioeconomic impacts. 
Affected Environment 

NUREG-1937 2-112 February 2011 

Figure 2-24. Map of Central Texas Gulf Coast, Showing Counties Potentially Affected by the 

Proposed Units 3 and 4 (STPNOC 2010a) 

For the purposes of this analysis, the review team divided the total population within the 

analytical area into three major groups: residents who live permanently in the area; transients 

who may temporarily live in the area but have a permanent residence elsewhere; and migrant 

workers who travel into the area to work and then leave after their job is done. Transients and 

migrant workers are not fully characterized by the U.S. Census, which generally captures only 

resident populations. 

2.5.1.1 Resident Population 

Table G-1 in Appendix G shows the estimated population in 2000 within 50 mi of the center of 

the proposed STP site. In this table, the center of the circle is the same as on Figures 2.5-1 of 

the ER (STPNOC 2010a), midway between the power blocks for the existing Unit 2 and Unit 3 

of the proposed site, with concentric circles in 10 mi increments up to 50 mi from the proposed 

location. Resident population data for the area surrounding the STP site indicate low population 

densities and a rural setting. The transient population for 0–10 mi was added to the 2000 
Affected Environment 

February 2011 2-113 NUREG-1937 

resident population for use in the projections, and is reflected in Table G-1. The population 

projections for radii of more than 10 mi include only residents. 

The population growth rates shown in Table 2-18 were calculated for each county based on 

county projections obtained from the Texas State Data Center. The Texas State Data Center 

presents population projections by county for the period 2000-2060 by 10-year increments, 

using standard population cohort-component methods, age-specific birth and death rates 

calculated from the 2000 Census, and four age/gender specific migration rates. Their migration 

rates are calculated as: a) zero, b) the rates prevailing between 1990 and 2000 (a period of 

high population growth), c) half the rates between the 1990 and 2000, and d) the rates 

estimated for the period between 2000 and 2004. Both the Texas State Data Center and 

STPNOC considered the One-Half 1990–2000 Migration Scenario as the most appropriate 

population scenario for most counties for use in long-term planning, because migration is 

expected, but the 1990–2000 rate is not expected to be maintained over the coming years. 

STPNOC believed that the 2000–2004 Migration Scenario was based on estimates and 

represented too few years upon which to base a meaningful long-term trend (STPNOC 2010a). 

Table 2-18 shows the historical and projected populations for the nine counties closest to the 

STP site. The statewide Texas rate is provided for perspective. Table 2-18 shows that the 

estimated county populations for 2007 generally are less than the county populations projected 

by any of the methods that include migration. The exceptions are Brazoria and Fort Bend 

Counties, which continue to feel the strong growth of Houston at their eastern ends. For five of 

the nine counties (Matagorda, Calhoun, Jackson, Victoria, and Wharton) and for Texas as a 

whole, the estimated 2000-2007 growth rate for population was less than either Texas State 

Data Center 2000-2010 rate based on migration during the 1990s. For two counties (Lavaca 

and Colorado), it was between the two rates. Based on Table 2-18 the review team believes 

that for most counties in the area surrounding the STP site, a long-term population forecast 

based on half the 1990-2000 migration rate appears more reasonable than one that continues 

the rapid in-migration of the 1990s. Much of the more rapid population growth in Brazoria and 

Fort Bend counties also appears to be centered on their east ends, outside of the 50-mi region. 

The nearest population concentration is the Matagorda-Sargent CCD, 8 mi south-southeast 

of the site with a 2000 population of 3335. The nearest municipality with more than 

15,000 residents is Bay City, Texas, 13 mi north-northeast of the STP site, with a 

2000 population of 18,667 (STPNOC 2010a). Other municipalities in the 50-mi region, their 

2000 populations, and locations relative to STP, are presented in Table 2-19. Although Brazoria 

and Fort Bend Counties are included in the Houston-Baytown-Sugarland Metropolitan Statistical 

Area (MSA), the core Houston metropolitan area is slightly outside of the 50-mi region. The 

core of the Victoria Texas MSA (which includes Calhoun County) is also outside of the 50-mi 

region. The Houston-Baytown MSA had a 2000 population of 4,715,407 while the Victoria MSA 

had a 2000 population of 111,663 (STPNOC 2010a). 
NUREG-1937 2-114 November 2010 

Affected Environment Table 2-18. Historical and Projected Populations for Counties in the STP Region Year Matagorda Brazoria Calhoun Colorado Fort Bend Jackson Lavaca Victoria Wharton Texas Popu- lation Annual Percent Growth Popu- lation Annual Percent Growth Popu- lation Annual Percent Growth Popu- lation Annual Percent Growth Popu- lation Annual Percent Growth Popu- lation Annual Percent Growth Popu- lation Annual Percent Growth Popu- lation Annual Percent Growth Popu- lation Annual Percent Growth Popu- lation Annual Percent Growth 1970 27,913 N/A 108,312 N/A 17,831 N/A 17,638 N/A 52,314 N/A 12,975 N/A 17,903 N/A 53,766 N/A 36,729 N/A 11,196,730 N/A 1980 37,828 3.10% 169,587 4.60% 19,574 0.90% 18,823 0.70% 130,846 9.60% 13,352 0.30% 19,004 0.60% 68,807 2.50% 40,242 0.90% 14,229,191 2.40% 

1990 36,928 -0.20% 191,707 1.20% 19,053 -0.30% 18,383 -0.20% 225,421 5.60% 13,039 -0.20% 18,690 -0.20% 74,361 0.80% 39,955 -0.10% 16,986,510 1.80% 

2000 37,957 0.30% 241,767 2.30% 20,647 0.80% 20,390 1.00% 354,452 4.60% 14,391 1.00% 19,210 0.30% 84,088 1.20% 41,188 0.30% 20,851,820 2.10% 

2007 

Estimated 

36,930 -0.40% 291,729 2.70% 20,958 0.20% 21,925 1.00% 503,315 5.10% 14,598 0.20% 19,382 0.10% 86,756 0.40% 42,262 0.40% 23,834,206 1.90% 

2010 

Projected 

(1990-

2000 

Migration 

Rate) 

41,924 1.00% 314,415 2.70% 23,171 1.20% 22,655 1.10% 532,988 4.20% 16,069 1.10% 19,593 0.20% 95,665 1.30% 44,844 0.90% 26,058,565 2.30% 

2010 

Projected 

(2000-

2004 

Migration 

Rate) 

39,258 0.30% 308,517 2.50% 21,784 0.50% 22,854 1.10% 556,805 4.60% 14,799 0.30% 19,588 0.20% 89,928 0.70% 44,102 0.70% 25,105,646 1.90% 

2010 

Projected 

(Half 

1990-

2000 

Migration 

Rate) 

41,406 0.90% 287,643 1.80% 22,684 0.90% 21,693 0.60% 452,097 2.50% 15,571 0.80% 19,298 0.00% 94,193 1.10% 44,276 0.70% 24,330,612 1.60% 

2020 44,715 0.80% 335,925 1.60% 24,427 0.70% 23,113 0.60% 563,873 2.20% 16,745 0.70% 19,665 0.20% 107,437 1.30% 47,381 0.70% 28,005,788 1.40% 

2030 47,062 0.50% 383,598 1.30% 25,732 0.50% 24,064 0.40% 682,296 1.90% 17,432 0.40% 19,685 0.00% 117,096 0.90% 49,647 0.50% 31,830,589 1.30% 

2040 48,664 0.30% 429,766 1.10% 26,571 0.30% 24,782 0.30% 789,864 1.50% 17,759 0.20% 19,316 -0.20% 125,040 0.70% 50,968 0.30% 35,761,201 1.20% 

Sources: Texas State Data Center 2006, 2007; USCB 1973 
Affected Environment 

February 2011 2-115 NUREG-1937 

Table 2-19. Municipalities in the 50-mi Region Surrounding the STP Site

Municipality County 

2000 

Population 

Distance from 

STP (mi) Direction 

Angleton Brazoria 18,130 45 NE 

Bay City Matagorda 18,667 12 NNE 

Edna Jackson 5899 38 WNW 

El Campo Wharton 10,945 31 NNW 

Freeport Brazoria 12,708 43 ENE 

Lake Jackson Brazoria 26,386 40 NE 

Matagorda-Sargent CCD Matagorda 3335 8 SSE 

Palacios City Matagorda 5153 11 SW 

Port Lavaca Calhoun 12,035 37 SW 

Wharton Wharton 9237 36 N 

Source: STPNOC 2010a 

2.5.1.2 Transient Population 

Transients include seasonal or daily workers or visitors to large workplaces, schools, hospitals 

and nursing homes, correctional facilities, hotels and motels, and at recreational areas or 

special events. NRC Regulatory Guide 4.7 (NRC 1998) defines transient population as people 

who work, reside part-time, or recreate in an area but do not permanently reside there. 

However, the U.S. Census Bureau (USCB) includes residents of facilities such as nursing 

homes, hospitals, college dormitories and military quarters as part of the residential population, 

effectively excluding part of what could otherwise be considered “transient.” Transient 

population estimates (following the Census definition) for the area up to 10 mi radius around the 

STP site are included in Table G-1, of Appendix G. 

The major employment facilities in the area, in addition to STP, include OXEA Corporation and 

Equistar Chemicals LP, also known as Lyondell Corporation. OXEA Corporation is located 

approximately 3 mi north-northeast of STP’s plant and employs a total of 155 persons. 

Equistar, located about 4 mi east of the STP site, employs 194 workers (STPNOC 2010a). In 

addition, recreational attractions in the area attract thousands of visitors each year. 

Recreational opportunities in the area include Riverside Park, Bay-Cel Golf Club, Rio Colorado 

Golf Club, FM 521 River Park, Fisherman’s Motel and RV, Lighthouse RV Park, Matagorda 

Harbor, and the Mad Island WMA. Section 2.5.2.4 discusses recreational activities in the region 

more thoroughly and ER Table 2.5-24 shows the major sources of recreation in the region 

surrounding the STP site. 

More broadly, Table 2-20 shows the number of hotel nights available, occupancy, and estimated 

hotel nights stayed in the four counties nearest the STP site for the year 2006. The available 

hotel space (about 5200 rooms) would allow 1.9 million room nights, of which about 1.1 million 

(57 percent) are claimed by guests on an annual basis, for an annual average of about 

3000 occupied hotel rooms per night (Texas Tourism 2006). 
Affected Environment 

NUREG-1937 2-116 February 2011 

Table 2-20. Hotels Nights Available and Sold in Four-County Socioeconomic Impact Area 

Surrounding the STP Site, 2006 

County 

Hotel RoomNights Annual 

2006 (Thousand) 

Average 

Percent 

Occupancy 

Estimated 

Nights Sold 2006 

(Thousand) 

Matagorda 240.3 49.1 118 

Brazoria 650.4 58.7 382 

Calhoun 185.2 46.6 86.3 

Jackson 23 60.4 13.9 

Total 1099 53.7 600.2 

Source: Texas Tourism 2006 

Accounting for major employers (other than STP), overnight accommodations, major recreation 

areas, and marinas within the 10 mi radius, a total of 1622 transients could be present within the 

10 mi radius (STPNOC 2010a). No comparable estimate is available for the area outside of 

10 mi but within 50 mi. 

2.5.1.3 Migrant Labor 

The USCB defines a migrant laborer as someone who is working seasonally or temporarily and 

moves one or more times from one place to another to perform seasonal or temporary 

employment. During STP scheduled refueling outages, there is an influx of migrant construction 

labor to the area who are hired by STP to carry out fuel reloading activities, equipment 

maintenance, and other projects associated with the outage. STP employs approximately 1500-

2000 additional employees during every refueling outage, which occurs every 18 months for 

each unit (STPNOC 2010a). 

The 2002 Census of Agriculture indicates the migrant farm labor population is within 50 mi of 

the proposed site. Farm operators were asked whether any hired or contract workers were 

migrant workers, defined as a farm worker whose employment required travel that prevented 

the worker from returning to his permanent place of residence the same day. Migrants tend to 

work short-duration, labor-intensive jobs harvesting fruits and vegetables. Out of 4135 hired 

farm workers recorded in the four counties closest to the STP site, the 2002 Census of 

Agriculture records, only a small percentage met the definition of migrant workers. While there 

is no direct count of migrant labor, 3026 of the farm laborers worked less than 150 days, and 

only 95 of the 1051 farms reporting the presence of these short-term laborers reported any 

workers meeting the definition of migrant worker (DOA 2002). According to the Matagorda 

County Agricultural Extension Agency and the Texas Workforce Commission, there are few, if 

any migrant workers within 10 mi of the plant due to the mechanized nature of the agricultural 

industry in this area (STPNOC 2010a). 
Affected Environment 

February 2011 2-117 NUREG-1937 

2.5.2 Community Characteristics 

For a historical perspective in the 1940s, Matagorda County’s economy consisted of significant 

oil production and farms. Oil has dropped off because of lower oil prices and farms have 

declined due to consolidation and mechanization but agriculture still remains important. Growth 

has occurred because of new industries such as the Celanese plant and STP. In the 1940s, 

Brazoria County saw a large increase in manufacturing jobs, and the 1950s brought service 

companies such as Monsanto. Farm production also peaked in the 1950s. Later petroleum and 

mineral production and marketing along with extraction and manufacturing, the chemical 

industry, fishing and the recreation industry molded the county’s economy and development. 

After World War II the Aloca plant, the Union Carbide and Carbon Chemicals Company and 

other companies provided job opportunities. During the 1950s, agriculture, manufacturing and 

mineral-related companies comprised a majority of the local economy. Today, Calhoun County 

still has an agricultural based economy with cotton, cattle, corn and grain sorghum the chief 

products but plastics, aluminum manufacturing and other manufacturing are just as important to 

the county’s economy and development. Jackson County saw a significant decrease in farming 

during the 1930s, however, this was somewhat offset by the discovery of oil in 1934. 

Agriculture rebounded during World War II and by the 1990s Jackson County was a leading 

producer of rice and cattle with over 90 percent of the county used for farming and ranching 

(TSHA 2009a, b, c, d). 

The transportation network in the four counties really started developing in the early 20th century 

through the 1940s with construction of extensive railways to open the area to national markets 

and encourage immigration. However, since the 1980s, much of the track has been 

abandoned. Several waterways were developed or improved such as the clearing of a massive 

log jam on the Lower Colorado River and the creation of the Gulf Intracoastal Canal. There was 

push to build roads in the 1920s and 1930s after which improvements were made such as 

replacing ferries with bridges. 

The STP site sits near the Gulf Coast in a rural area with several small towns located within 

15 mi of the plant. The populations of Calhoun and Matagorda counties are about 60 percent 

minority, which is just slightly over the state average. Brazoria and Jackson counties are about 

45 percent minority, which is below the state average. Calhoun and Matagorda counties have a 

higher percentage of the population living below the poverty line than the Texas state average. 

The four-county socioeconomic impact area is described in terms of racial characteristics and 

income level in Table 2-21. 

Further discussion of the demographic composition of the socioeconomic impact area can be 

found under “Environmental Justice” in Section 2.6. The remainder of this section addresses 

community characteristics including the regional economy, transportation networks and 

infrastructure, taxes aesthetics and recreation, housing, community infrastructure and public 

services, and education. 
Affected Environment 

NUREG-1937 2-118 February 2011 

Table 2-21. Minority and Low-Income Populations (2000 U.S. Census) 

County 

Percentage 

Minority 

Percentage 

Below Poverty 

United States 30.9% 12.4% 

Texas 58.6% 15.4% 

 Brazoria 43.4% 10.2% 

 Calhoun 60.6% 16.4% 

 Jackson 45.8% 14.7% 

 Matagorda 61.1% 18.5% 

Source: USCB 2000a 

2.5.2.1 Economy 

The principal economic centers in Matagorda, Brazoria, Jackson, and Calhoun Counties 

include: Bay City (Matagorda County); Angleton (Brazoria County); Brazosport CCD (Brazoria 

County), which contains the Lake Jackson-Clute-Freeport area; Port Lavaca (Calhoun County); 

and Edna (Jackson County). Matagorda County’s economy is based primarily on ranching 

(cattle), farming agriculture (rice, cotton, sorghum, and corn), oil and natural gas production and 

refinement, petrochemical production, electricity generation, and commercial fishing and 

fisheries. Brazoria County’s economy is largely based on petroleum and chemical production, 

mineral resource extraction (oil, gas, sulfur, salt, lime, sand, and gravel), tourism, cattle 

ranching, and agriculture (rice, beans, sorghum, nursery plants, corn, cotton, and timber). 

Houston has a large influence on the economy of northeast Brazoria County. In the four 

counties most significantly impacted by the development and operation of STP, the government 

and government enterprises industry employs the greatest number of workers. Other important 

sectors of employment include state and local government, construction, and retail trade 

(BEA 2008). Table 2-22 shows industry in the four counties. The U.S. Department of Labor 

collects data on construction workforce sizes by state and by selected MSAs. Employment in 

the U.S. Department of Labor category of Construction and Extraction Occupations, based on 

data gathered in 2002 through 2005, was 141,650 for the Houston-Baytown-Sugarland MSA 

(STPNOC 2010a). 

The top employers in the four-county socioeconomic impact area are listed in Table 2-23. In 

addition to STPNOC, only two other large employers are within the 10-mi radius. The first 

employer is the OXEA Corporation, which is located 5 mi north-northeast of the STP site. The 

plant produces industrial chemicals and employs approximately 155 workers. The second 

employer is Lyondell Chemical, which produces polyethylene chemicals. It is located 

approximately 7 mi east of the STP site and employs approximately 194 workers (STPNOC 

2008d). 
Affected Environment 

February 2011 2-119 NUREG-1937 

Table 2-22. Employment by Industry, 2006 

Industry Matagorda Brazoria Calhoun Jackson Total 

Total Employment 16,188 121,526 12,912 7558 158,184

Wage and Salary Employment 10,897 89,190 10,185 5247 115,519

Proprietors Employment 5291 32,336 2727 2311 42,665

 Farm Proprietors Employment 983 2158 321 1016 4478

 Nonfarm Proprietors Employment 4308 30,178 2406 1295 38,187

Farm Employment 1280 2429 394 1229 5332

Nonfarm Employment 14,908 119,097 12,518 6329 152,852

Private Employment 12,280 101,960 10,980 5196 130,416

 Forestry, Fishing and Related Activities 833 538 336 176 1883

 Mining 217 1147 268 (D) 1632

 Utilities (D) 261 (D) (D) 261

 Construction 827 17,190 2136 738 20,891

 Manufacturing 489 12,515 3004 (D) 16,008

 Wholesale trade 309 2829 (D) 258 3396

 Retail trade 1746 13,867 1196 667 17,476

 Transportation and Warehousing (D) 3967 195 (D) 4162

 Information 100 914 69 92 1175

 Finance and Insurance 398 3687 452 230 4767

 Real Estate and Rental and Leasing 728 5604 303 131 6766

 Professional and Technical Services 473 6323 425 277 7498

 Management of Companies and Enterprises 27 107 (D) 0 134

 Administrative and Waste Services 808 6621 (D) 124 7553

 Educational Services (D) 1271 (D) 15 1286

 Health Care and Social Assistance (D) 7869 (D) 262 8131

 Arts, Entertainment, and Recreation 141 1679 84 31 1935

 Accommodation and Food Services 1084 7113 798 293 9288

 Other Services, Except Public 

Administration 1358 8458 603 431 10,850

 Government and Government Enterprises 2628 17,137 1538 1133 22,436

 Federal, Civilian 95 515 45 36 691

 Military 85 691 88 32 896

 State and local 2448 15,931 1405 1065 20,849

 State government 105 2864 67 46 3082

 Local government 2343 13,067 1338 1019 17,767

Source: BEA 2008 

Note (D): As reported by the United States Bureau of Economic Analysis, “not shown to avoid disclosure of 

confidential information, but the estimates for this item are included in the totals.”
Affected Environment 

NUREG-1937 2-120 February 2011 

Table 2-23. Major Employers in Matagorda, Brazoria, Calhoun, and Jackson Counties 

Employer Private/Public Type Number 

Matagorda County(a)

South Texas Project Private 

Electric Generation and 

Transmission 1365 

Bay City Independent School District Public Education 700 

Matagorda County Hospital District Public Hospital 475 

Wal-Mart Associates, Inc. Private Retail 300 

Palacios Independent School District Public Education 270 

HEB Grocery Private Retail 260 

Matagorda County Public Public Service 260 

Lyondell Chemical Company (Equistar) Private Chemical 194 

OXEA Corporation (formerly Celanese) Private Chemical 155 

Brazoria County(b)

The Dow Chemical Company Private Chemical 4570 

Texas Department of Criminal Justice Public Prison System 2440 

Infinity Group Private Specialty Contractor 2413 

Brazosport Independent School District Public Education 2015 

Wal-Mart Associates Inc. Private Retail 1880 

Pearland Independent School District Public Education 1810 

Alvin Independent School District Public Education 1758 

Brazoria County Public Public Service 1313 

 Industrial Specialists Inc. Private Specialty Contractor 1069 

ConocoPhillips Private Refining 900 

Calhoun County(b)

Inteplast Group Private Chemical 1700 

Formosa Plastics Private Chemical 1500 

Dow Chemical Private Chemical 660 

Alcoa Private Chemical 630 

Calhoun County ISD Public Education 613 

King Fisher Marine Service Private Dredging 330 

HEB Grocery Private Retail 275 

INEOS Nitriles Private Chemical N/A 

Calhoun County Public Government N/A 

Harmony Industrial Private Contract Employees N/A 

International Bank of Commerce Private Business N/A 

SSI Management Group Private Contract Employees N/A 

Seadift Coke LP Private Chemical N/A 

Jackson County 

The Inteplast Group Ltd. Private Plastic Film 1600 

Sources: STPNOC 2010a, 2008d; CCEDC 2008; and Exelon 2008. 

(a) Data were collected in 2007. 

(b) Data undated. 
Affected Environment 

February 2011 2-121 NUREG-1937 

The STP site currently employs approximately 1300 full-time employees, with an additional 

1500-2000 workers during maintenance outages (STPNOC 2010a). STP is the largest 

employer in Matagorda County. Table 2-16 shows where the STP site’s employees lived in 

January 2007. The review team simplified its analysis by concentrating on Matagorda, Brazoria, 

Calhoun, and Jackson Counties. Approximately 86 percent live in these four counties. 

Although an additional 8.6 percent live in Wharton and Fort Bend Counties, these are relatively 

large population counties and would not be expected to be significantly affected by the addition 

of a small number of construction or operations workers employed by the two proposed units. 

The review team used the distribution of the STP employees as the basis for several 

demographic assumptions in its economic impact assessment discussed in Chapters 4 and 5 of 

this EIS. 

Table 2-24 shows the number of workers employed and the unemployment rates for Matagorda, 

Brazoria, Calhoun, and Jackson Counties and the State of Texas for 1995 and 2005. These 

data show the number of employed workers in Matagorda County and Calhoun County grew 

more slowly than the State’s rate of 1.83 percent per year, adding 0.12 and 0.23 percent 

respectively per year to employment during the decade, while the much larger Brazoria County 

grew much faster than the state—2.97 percent per year. Jackson County saw a 2.24 percent 

decrease in the number of employed workers. Unemployment decreased significantly in all the 

counties except for Jackson County. 

2.5.2.2 Taxes 

Several types of taxes would be impacted by proposed Units 3 and 4. The following 

subsections describe major taxes, their structure and annual dollar yield. Taxes included in this 

discussion include personal income and corporate franchise taxes, sales and use tax, and 

property taxes. 

Personal Income and Corporate Franchise Taxes 

The State of Texas does not levy a personal income tax on individuals. Texas’s primary 

business tax is the franchise tax, imposed on each taxable entity organized in Texas or doing 

business in Texas. In 2006, the State of Texas received $2.6 billion (3.6 percent of its total net 

revenue of $72.4 billion) from franchise taxes. The revised franchise tax base as of January 1, 

2008, is the taxable entity’s margin. Margin equals the lowest of three calculations: total revenue 

minus cost of goods sold, total revenue minus compensation, or total revenue times 70 percent. 

The tax rates are 0.5 percent of the margin for entities primarily engaged in wholesale or retail 

trade and 1.0 percent for all other taxable entities (STPNOC 2010a). STPNOC qualifies as an 

“other taxable entity” and, therefore, is subject to the 1.0 percent tax rate. 
Affected Environment 

NUREG-1937 2-122 February 2011 

Table 2-24. Employment and Unemployment Statistics for Matagorda, Brazoria, Calhoun, and 

Jackson Counties 

County Year 

Labor 

Force Employment Unemployment 

Unemployment 

Rate 

Matagorda 1995 17,430 14,921 2509 14.4% 

 2005 16,430 15,097 1333 8.1% 

Avg. Annual Growth Rate -0.59% 0.12% -4.69% 

Brazoria 1995 105,654 97,672 7982 7.6% 

 2005 134,404 126,697 7707 5.7% 

Avg. Annual Growth Rate 2.40% 2.97% -3.51% 

Calhoun 1995 9548 8660 888 9.3% 

 2005 9407 8863 544 5.8% 

Avg. Annual Growth Rate -0.15% 0.23% -3.87% 

Jackson 1995 8514 8170 344 4.0% 

 2005 6668 6341 327 4.9% 

Avg. Annual Growth Rate -2.43% -2.24% -0.49% 

Four-County 

Total 

1995 141,146 129,423 11,723 8.3% 

2005 166,909 156,998 9911 5.9% 

Avg. Annual Growth Rate 1.67% 2.13% -1.55% 

Texas 1995 9,572,436 8,985,635 586,801 6.1% 

 2005 11,225,882 10,626,606 896,276 5.3% 

Avg. Annual Growth Rate 1.59% 1.83% 5.27% 

Sources: BLS 2008; STPNOC 2010a 

Sales and Use Taxes 

The State sales tax rate for Texas is 6.25 percent of the sale price of taxable goods and 

services. Local jurisdictions, including cities, counties, transit authorities, and some special 

purpose districts, may also impose a local sales tax after voter approval but may not exceed 

2 percent altogether. The State of Texas received $18.3 billion (25 percent of its revenue) from 

sales tax collections in 2006 (STPNOC 2010a). 

Neither Matagorda County nor the special purpose districts in the county levy sales tax. Cities 

in Texas may impose additional sales tax, up to the maximum of 2 percent, for the following 

purposes: sales tax for general fund purposes (1 percent); additional sales tax for property tax 

reduction (up to 0.5 percent); sales tax for street maintenance (0.25 percent); sales tax for 

industrial and economic development (up to 0.5 percent); and sales tax for sports and 

community venues (up to 0.5 percent). The cities of Bay City and Palacios in Matagorda 

County impose the maximum 2 percent tax rate, making the total sales tax 8.25 percent in these 

cities. Brazoria, Calhoun and Jackson counties all have a county tax of 0.5 percent and the 

larger economic centers in these counties generally have a 1.5 percent tax for a total sales tax 

of 8.25 percent (Texas Comptroller 2008). 
Affected Environment 

February 2011 2-123 NUREG-1937 

The State of Texas currently imposes a 6 percent hotel occupancy tax on rooms in a hotel 

costing at least $15 per day; however, stays of at least 30 consecutive days are exempt from 

the tax. Texas received $308 million (0.4 percent of its revenue) from this tax in 2006. Cities 

and some counties are eligible to adopt a hotel occupancy tax on rooms costing at least $2 per 

day. To implement a local occupancy tax a majority vote by the governing body is required and 

the tax revenues must be used to directly promote tourism and the convention and hotel 

industry. The City of Bay City has imposed a 7 percent sales tax above the 6 percent state 

sales tax on eligible hotel rooms (STPNOC 2010a). 

Property Taxes 

Most private property owners pay property taxes to the county and a local school district; 

however, other local jurisdictions to whom property owners pay taxes may include the host city, 

hospital district, and junior college district. The sole local source of tax revenue for school 

districts is the property tax (STPNOC 2010a). Property values are set by the county appraisal 

district and the tax rate is set by the governing body of each local jurisdiction. Tax rates are 

expressed as an amount per $100 of assessed value. The tax levy is determined by multiplying 

the total taxable value by the total tax rate per $100 of value. Total tax rates can include a 

maintenance and operation (M&O) rate (day to day maintenance and operations), an interest 

and sinking fund (I&S) rate, or both (STPNOC 2010a). 

Matagorda County is more likely to be impacted by property taxes related to new nuclear units 

at the STP site than Brazoria, Calhoun, and Jackson Counties, because the STP site is within 

the Matagorda County boundaries. The 2005 total county property tax rate for Matagorda 

County was $0.31 per $100 of assessed value, all part of the M&O rate. Matagorda County 

levied approximately $8.1 to $8.2 million annually in property taxes between 2001 and 2005; 

and the owners of the STP facility are their largest property taxpayers. For the first half of this 

decade, STP property tax payments to the county, excluding the hospital and special districts, 

represented nearly three-fourths of Matagorda County’s total tax revenues. Table 2-25 presents 

the total property taxes collected by the county, the total property taxes the STP owners have 

paid to Matagorda County, and the percent of the total county property taxes that are paid by 

the owners (STPNOC 2010a). 

The STP owner’s agreement with Matagorda County allows it to pay a service fee in lieu of 

property taxes with an annual revenue cap of $6.1 million. The owners also have a similar 

agreement with the local hospital district, capped at $2.7 million per year. The STP site is within 

the boundaries of four additional special taxing districts: Navigation District #1, Drainage District 

#3, the Palacios Seawall District, and the Coastal Plains Groundwater District. The owners pay 

the standard millage rates assigned by these taxing districts each year. Table 2-26 shows the 

districts, tax rates, and owner payments to each taxing entity for 2001 through 2006 (STPNOC 

2010a). 
Affected Environment 

NUREG-1937 2-124 February 2011 

Table 2-25. Matagorda County Property Tax Information, 2000-2005 (in millions of dollars) 

Year 

Total Taxable 

Value 

Total 

County 

Levy 

STP Payments 

to County(a)

STP Payments 

as % of Total(a)

2001 $2788 $8.18 $5.97 72.9 

2002 $2559 $8.23 $6.10 74.1 

2003 $2580 $8.21 $6.10 74.3 

2004 $2551 $8.12 $6.10 75.1 

2005 $2655 $8.19 $6.10 74.5 

2006 N/A N/A $6.10 N/A 

Source: STPNOC 2010a 

(a) Reflects payments only to Matagorda County; does not include payments to the 

Hospital District or other special districts. 

Table 2-26. Property Tax Statistics for Matagorda County and Special Districts 2001-2006 

(in millions of dollars) 

Year Taxing District 

Rate/$100 of 

Assessed 

Valuation Levy 

Other 

Fees 

Total STP 

Payment

2001 Matagorda County $0.29 $3.36 $2.61 $5.97 

 Matagorda County Hospital 0.12524 $1.43 $1.12 $2.55 

 Navigation District #1 0.03981 $0.46 $0.00 $0.46 

 Drainage District #3 0.019 $0.22 $0.21 $0.42 

 Palacios Seawall 0.03487 $0.40 $0.37 $0.77 

Total STP Owner Payments $5.86 $4.30 $10.17 

2002 Matagorda County $0.32 $2.96 $3.14 $6.10 

 Matagorda County Hospital 0.1507 $1.39 $1.00 $2.39 

 Navigation District #1 0.03981 $0.37 $0.00 $0.37 

 Drainage District #3 0.0246 $0.23 $0.00 $0.23 

 Palacios Seawall 0.0422 $0.39 $0.00 $0.39 

 Coastal Plains Groundwater [2] 0.005 $0.05 $0.00 $0.05 

Total STP Owner Payments $5.37 $4.14 $9.51 

2003 Matagorda County $0.32 $2.88 $3.22 $6.10 

 Matagorda County Hospital 0.1614 $1.46 $1.00 $2.46 

 Navigation District #1 0.03981 $0.36 $0.00 $0.36 

 Drainage District #3 0.0276 $0.25 $0.00 $0.25 

 Palacios Seawall 0.0454 $0.41 $0.00 $0.41 

 Coastal Plains Groundwater 0.005 $0.05 $0.00 $0.05 

Total STP Owner Payments $5.41 $4.22 $9.63 
Affected Environment 

February 2011 2-125 NUREG-1937 

Table 2-26. (contd) 

Year Taxing District 

Rate/$100 of 

Assessed 

Valuation Levy 

Other 

Fees 

Total STP 

Payment

2004 Matagorda County $0.32 $2.32 $3.78 $6.10 

 Matagorda County Hospital 0.20999 $1.53 $1.00 $2.53 

 Navigation District #1 0.03981 $0.29 $0.07 $0.36 

 Drainage District #3 0.0322 $0.23 $0.02 $0.25 

 Palacios Seawall 0.0454 $0.33 $0.08 $0.41 

 Coastal Plains Groundwater 0.005 $0.04 $0.01 $0.05 

Total STP Owner Payments $4.73 $4.96 $9.69 

2005 Matagorda County $0.31 $1.95 $4.15 $6.10 

 Matagorda County Hospital 0.2124 $1.34 $1.00 $2.34 

 Navigation District #1 0.03981 $0.25 $0.00 $0.25 

 Drainage District #3 0.0322 $0.20 $0.00 $0.20 

 Palacios Seawall 0.0354 $0.22 $0.00 $0.22 

 Coastal Plains Groundwater 0.005 $0.03 $0.00 $0.03 

Total STP Owner Payments $4.01 $5.15 $9.15 

2006 Matagorda County $0.27 $2.44 $3.66 $6.10 

 Matagorda County Hospital 0.17214 $1.57 $1.00 $2.57 

 Navigation District #1 0.03758 $0.34 $0.00 $0.34 

 Drainage District #3 0.022 $0.20 $0.00 $0.20 

 Palacios Seawall 0.02528 $0.23 $0.00 $0.23 

 Coastal Plains Groundwater 0.00433 $0.04 $0.00 $0.04 

Total STP Owner Payments $4.82 $4.66 $9.48 

Source: STPNOC 2010a

Schools are funded solely through local property taxes. Districts are designated either “property 

rich” (Texas Education Code, Chapter 41) or “property poor” (Texas Education Code, Chapter 

42) based on a wealth benchmark, calculated as the district’s total assessed property valuation 

divided by the total number of students. Those districts with a total wealth per student above 

the State benchmark are considered Chapter 41 and those below the benchmark are Chapter 

42. The Chapter 41 “property wealthy” districts are required to send a portion of their local 

property tax revenue in to the State for redistribution to Chapter 42 districts. As with property 

taxes paid to local jurisdictions, school property taxes consist of both M&O and I&S components 

and Chapter 41 districts are allowed to keep all I&S collections (STPNOC 2010a). Recent 

changes by the Texas legislature in 2006 to provide residential tax relief has placed an annual 

cap on Independent School District (ISD) property tax rates used to fund M&O. Under the new 

rules, if school boards set a property tax rate above the State cap, the rate would have to be 

approved in a “rollback” election. The M&O portion of the rollback tax rate is the tax rate that 
Affected Environment 

NUREG-1937 2-126 February 2011 

would be needed to raise eight percent more operating funds than the previous year. The 

exception to the rollback election would be if a district was responding to a natural disaster 

(STPNOC 2010e). 

STP owners pay taxes to the Palacios ISD where STP is the largest property taxpayer, 

representing an average of 83 percent of Palacios ISD annual revenues between 2000 and 

2005. Palacios ISD is considered a Chapter 41 or “property wealthy” district and therefore is 

required to send a portion of their tax collections to the State for redistribution. Table 2-27 

shows Palacios ISD’s total revenues, the portion sent to the State and the STP owners’ 

contributions between 2000 and 2005 (STPNOC 2010a). 

Table 2-27. Palacios Independent School District Property Tax Revenues and Disposition 

2000-2005 (in millions of dollars) 

Year 

Total 

District 

Revenue 

STP 

Owner 

Total 

Pmts to 

ISD 

STP 

Owner 

Payments 

as a 

Portion of 

Revenues 

to State 

Excess 

Percentage 

(goes to 

State) 

Revenue 

Remaining 

in District 

STP 

Owner 

Portion 

Remaining 

in District 

STP 

Owner 

Payments 

as % of 

Revenues 

Remaining 

in District 

2000 $14.90 $12.78 $5.38 42.1% $8.63 $7.40 85.8 

2001 $15.94 $15.78 $8.54 54.1% $7.32 $7.24 99.0 

2002 $15.29 $12.94 $5.78 44.7% $8.46 $7.15 84.6 

2003 $14.92 $12.40 $5.22 42.1% $8.63 $7.18 83.1 

2004 $13.87 $10.55 $3.76 35.6% $8.93 $6.79 76.0 

2005 $12.88 $9.19 $2.72 29.6% $9.07 $6.48 71.4 

Total $87.80 $73.63 $31.39 $42.24 

Source: STPNOC 2010a 

Revenues and Expenditures 

Matagorda County’s total general revenues for 2006 were $17.1 million. Ninety-one percent of 

its general revenues are from property taxes, of which the STP owners paid $6.1 million 

(35.6 percent). Expenditures, including general revenues and restricted funds, were 

$17.9 million. Since Brazoria County is part of the Houston metropolitan area, it is more 

urbanized than Matagorda County. In 2006, Brazoria County’s General Fund revenues were 

$66.5 million, with property taxes contributing 84 percent and expenditures for 2006 were 

$66.5 million (STPNOC 2010a). Jackson County’s general revenues for 2007 were $7.2 million, 

with taxes representing $5.2 million and expenditures were $5.5 million (Jackson County 2008). 

Calhoun County’s general revenues for 2007 were an estimated $22.6 million and expenditures 
Affected Environment 

February 2011 2-127 NUREG-1937 

were approximately $9.97 million (Calhoun County 2008). STP is not a significant contributor to 

tax revenues in Brazoria, Calhoun, or Jackson Counties. 

2.5.2.3 Transportation 

The STP site’s transportation network includes State highways, U.S. highways, FM roads, 

county roads, two railroad networks, nine regional airports and a waterway via the Lower 

Colorado River. Public transportation in Matagorda County is provided by RTransit. RTransit 

provides services by appointment to the rural general public, elderly, and persons with 

disabilities (STPNOC 2010a). In its current configuration and mission of serving special needs, 

RTransit would have no impact on, and would be unaffected by, the proposed Units 3 and 4 at 

STP. 

Roads 

No interstate highways are located within the 50-mi vicinity, but there are two U.S. highways. 

Highway 59 runs northeast-southwest connecting Fort Bend, Wharton, Jackson and Victoria 

Counties and Highway 87 runs northwest-southeast and connects Victoria and Calhoun 

Counties. Many of the roads in the socioeconomic impact area are county roads or FM roads, 

which are relatively light-duty rural roads. A number of FM and county roads intersect the major 

highways and connect to the towns within these counties, providing outlying areas access to the 

State and U.S. Highway system. For example, State Highway 60 runs north-south connecting 

Highway 59 to FM 521, providing access to the STP site (STPNOC 2010a). Figure 2-25 

presents the major road networks in the 50-mi region around the STP site, and Figure 2-26 

highlights the most likely employee commuter routes to and from the site on local roads. 

STPNOC believes that workers commuting from Matagorda County would take one of five 

routes that connect to FM 521 and access the site. Table 2-28 lists the Matagorda County 

roadways that STP workers would use to access the plant, the Texas Department of 

Transportation (TxDOT) road classifications for each road, the number of lanes, the 2005 

Average Annual Daily Traffic (AADT) counts at key locations and threshold capacity. Workers 

commuting from the east side of Matagorda County and all of Brazoria County would likely take 

Highway 60 south, exiting onto FM 521 west to the STP site. From Calhoun County and 

Jackson Counties, workers would likely take State Highway 35 and State Highway 111, 

respectively before connecting to local roads near the site. 

Crowding on roadways is often described by Transportation Research Board “Level of Service” 

(LOS) designations. LOS defines the flow of traffic on a designated highway. LOS designations 

can range from LOS A (traffic freely flowing) to LOS F (a point where traffic flow exceeds the 

design capacity of the highway resulting in severe congestion). There is no Transportation 

Research Board LOS determination for these Texas roads; however, TxDOT does maintain 

capacity data for these roads in the form of usage (AADT) and functional class system 

(STPNOC 2010a). 
Affected Environment 

NUREG-1937 2-128 February 2011 

Figure 2-25. Road, Highway, and Rail Transportation System (STPNOC 2010a) 

The 2000 Matagorda County population was 37,957 and is expected to increase by 9 percent 

by 2010 and 18 percent by 2020 (Table 2-18). An average outage work force of approximately 

1500 to 2000 additional workers for existing STP Units 1 and 2 would use FM 521 for 

approximately one month during every refueling outage, scheduled for each reactor, and would 

add 700 to 800 vehicles per day temporarily to the traffic counts on FM 521 in Table 2-28. 

(STPNOC 2010a). 

Rail 

There is no passenger rail service in the four-county socioeconomic impact area, but there are 

two main freight rail lines near the STP site. The Burlington Northern Santa Fe line runs northsouth, ending in Matagorda. The Union Pacific Railroad runs east-west from Brazoria County 

and continues westward into Jackson County, eventually turning southward along the Texas 

Gulf Coast and heading toward Mexico. Both lines have spurs leading to industrial facilities. 
Affected Environment 

February 2011 2-129 NUREG-1937 

Figure 2-26. Main Routes to STP Site (STPNOC 2010a) 

STPNOC reports that a 9-mi railroad spur that heads north from the site to the main east-west 

rail line is currently “out-of-service.” This line formerly served the STP site and STPNOC 

anticipates that it would be repaired to support building Units 3 and 4. The only railcars with 

access to this railroad spur are consigned to the STP site (STPNOC 2010a). STPNOC states it 

would follow all environmental requirements and use protective measures while repairing the 

spur (STPNOC 2008e). 

Waterways 

The STP site is located 10 mi north of Matagorda Bay on the west side of the Lower Colorado 

River. The U.S. Coast Guard is the primary enforcer of regulations related to barges making 

STP deliveries while TPWD also patrols the river to enforce State regulations. Located on the 

east side of the STP site is a barge slip used for delivery of major equipment during construction 

of the first two units at STP. It is expected to be used for deliveries associated with proposed 

Units 3 and 4 (STPNOC 2010a). The STP barge slip is within tidal reaches of the Gulf of 

Mexico and is not impacted by seasonal low water issues (STPNOC 2008e). 
Affected Environment 

NUREG-1937 2-130 February 2011 

Table 2-28. Roadway Use Statistics for Most Likely Routes to the STP Site 

Roadway and Location(a)

Number 

of 

Lanes Type 

TXDOT Road 

Classification 

Average 

Annual Daily 

Traffic 

(AADT) for 

2005(b)

Threshold 

Capacity 

(passenger 

cars per 

hour)(c)

Highway 60 south to FM 521 west 2 Undivided Rural Major Collector 3880 2300 

FM 2078 west to FM 2668 south 2(d) Undivided Rural Minor Arterial 450 4200 

FM 2668 south to FM 521 west 2 Undivided Rural Major Collector 1100 2300 

FM 521 west to Highway 35 west 2 Undivided Rural Major Collector 1330 2300 

FM 1468 south to FM 521 east 2(d) Undivided Rural Minor Arterial 600 4200 

FM 1095 south to FM 521 east 2 Undivided Rural Major Collector 480 2300 

FM 2853 south to FM 521 east 2 Undivided Rural Major Collector 580 2300 

FM 521 west 2 Undivided Rural Major Collector 2530 2300 

FM 521 east 2 Undivided Rural Major Collector 1543 2300 

Source: STPNOC 2010a 

(a) The traffic counts (AADTs) identified on Figure 2-26 correspond to those listed in this table. 

(b) Traffic counts for a 24-hr time period. 

(c) Capacity used in travel demand modeling by TxDOT, metropolitan planning organizations, and local 

governments. The capacity is typically based on level of service (LOS) C (stable flow) based on the 

Transportation Research Board Highway Capacity Manual. LOS A or B (free flow to reasonably free flow) may 

also be used as the threshold capacity level in less congested urban areas. 

(d) Rural Minor Arterial value form Suburban Fringe Column. 

Air 

The closest major airport in the area is outside the 50-mi radius in Houston. There are two 

airports in Matagorda County and one in each of the other three counties within the economic 

impact region. Most of the regional airports primarily support agricultural aviation. 

2.5.2.4 Aesthetics and Recreation 

Table 2-29 lists the major recreation areas (state parks and WMAs) within 50 mi of the STP site. 

There are no major recreation facilities such as destination amusement parks or professional 

sports venues within 50 mi of STP. A variety of annual events are held in Bay City. These 

include the Matagorda County Fair and Rodeo, which takes place in March. Other annual 

events held in Bay City that attract outside visitors include the Bay City Chamber Annual Fishing 

Tournament in May, the Jazz Festival in July, the Shrimporee and Blessing of the Fleet in 

August, the Bull Blast in October, and the Fisherman’s Festival in December (STPNOC 2010a). 
Affected Environment 

February 2011 2-131 NUREG-1937 

Table 2-29. Wildlife Management Areas and Parks Within 50 mi of the STP Site 

Name Acreage Location

Annual 

Visitors Overnight Facilities

Wildlife Management Areas

Matagorda Island 56,688 Calhoun County 1100 Primitive Camping 

Mad Island 7200 9 mi east of Collegeport – 

Matagorda County 

1200 None 

Peach Point 11,938 West of Freeport near 

Jones Creek, Brazoria 

County 

2700 None 

D.R. Winterman 246 Egypt, Wharton County Less than 10 None 

Mad Island Marsh 

Preserve 

7063 South east of Collegeport, 

Matagorda County 

1700 None 

Big Boggy National 

Wildlife Refuge 

5000 Wadsworth, Brazoria 

County 

250 None 

San Bernard National 

Wildlife Refuge 

45,311 Matagorda and Brazoria 

Counties 

32,000 None 

Brazoria National 

Wildlife Refuge 

43,388 Angleton, Brazoria County 35,000 None 

Nannie M. Stringfellow 

Wildlife Management 

Area 

3664 8 mi from Brazoria, 

Brazoria County 

300 None 

Parks

Brazos Bend State 

Park 

5000 Needville, Fort Bend 

County 

206,000 Campsites with water and 

electricity 

LCRA Hollywood 

Bottom 

36 Along the Colorado River 

south of Wharton, 

Wharton County 

3700 Camping with limited 

facilities 

LCRA Matagorda Bay 

Nature Park 

1600 Mouth of the Colorado 

River on the Matagorda 

Peninsula -Matagorda 

County 

25,000(a)

 Tent camping on beach 

70 site RV-park with full 

utility hook-ups 

LCRA FM-521 River 

Park 

13 4 mi west of Wadsworth 

on FM 521-Matagorda 

County 

3000 None 

Source: STPNOC 2010a 

(a) This number reflects how many overnight RV stays that have occurred since the park opened. 

The closest state park to the STP site is Brazos Bend in Needville (Fort Bend County), 

approximately 35 mi from the STP site. Birding is a major tourist attraction in the 50-mi STP 

region and Matagorda County has ranked first in the North American Audubon CBC for the past 

nine years. The Great Texas Coastal Birding Trail goes through many areas within 50 mi of 

STP and 14 State-recognized birding sites are located in Matagorda County. These sites 

include pull-outs along FM 2031 (as well as other local roads) and the Matagorda County 
Affected Environment 

NUREG-1937 2-132 February 2011 

Birding Nature Center, with trails and observation platforms (TPWD 2009c). With its 110 ac of 

man-made seasonally flooded prairie wetlands that host many species of wintering ducks and 

roosting geese, the STP site is a stop along the Birding Trail. There is an observation area and 

tours are available through the Visitors Center. Migrant shorebirds and other water birds can be 

seen onsite in the spring (STPNOC 2010a). 

The Matagorda Bay area recreation activities include camping, hiking, bicycling, surfing, 

swimming, beach combing, bird watching, nature study, fishing, passenger ferry, on-island 

shuttle and scheduled tours. With the exception of peak times, Matagorda Beach and Sargent 

Beach receive less than 100 visitors a day. There are two local outriggers providing guided 

tours of the Colorado River and an annual fishing tournament that occasionally uses the 

Colorado River (STPNOC 2008a). 

Existing STP Units 1 and 2 do not have cooling towers. Instead, they have a 7000-ac MCR. 

The 13-mi embankment of the MCR is visible from the southeast along the Colorado River and 

other points surrounding the site. The tallest structures on the site are the 145-ft high reactor 

containment domes, which are visible from FM 521, the closest road to the site. They are also 

visible from secondary roads from points 6.5 to 7 mi to the southwest. The terrain surrounding 

the site is rather flat and treeless, so there is little to screen the site from area roadways. No 

STP site facilities can be seen from Matagorda Bay, the Intracoastal Waterway or from any of 

the recreation areas listed in Table 2-29 (STPNOC 2010a). 

2.5.2.5 Housing 

Approximately 86 percent of current STP 1 and 2 employees reside in Brazoria (22.4 percent), 

Calhoun (1.6 percent), Jackson (1.3 percent) and Matagorda (60.7 percent) counties. An 

additional 14 percent are distributed across at least 16 other counties (see Table 2-16). Within 

50 mi of the proposed site, there are residential areas in and near cities and towns, smaller 

communities, and farms. 

Rental property is scarce in the rural areas of the region, but is available in the larger 

municipalities such as Bay City, Palacios, Edna, Port Lavaca, Angleton, Pearland, Alvin, and the 

Brazosport CCD (Lake Jackson-Clute-Freeport) area. In the vicinity of the STP site, housing 

structures are generally isolated, single-family homes. Newer residential developments are 

primarily associated with the towns or cities in the socioeconomic impact area. 

Table 2-30 provides the number of housing units and vacancies for the four-county 

socioeconomic impact area: Brazoria, Calhoun, Jackson, and Matagorda. While some more 

recent data are available for some larger counties in Texas, this was not true for all of the four 

counties of interest. Consequently, year 2000 data are presented in this analysis for 

consistency across counties. While the review team believes the data will differ between 2000 

and when building begins, the review team also believes that most of the housing markets 
Affected Environment 

February 2011 2-133 NUREG-1937 

would be larger and more able to accept additional population and, therefore, use of more 

current population data would not change the conclusions of this report. In 2000, there were a 

total of 126,022 housing units in the socioeconomic impact area, with an average vacancy rate 

of 13.8 percent. The vacancy rates for Calhoun, Jackson, and Matagorda counties were higher 

than the average rate for the four-county socioeconomic impact area, while the vacancy rate for 

Brazoria County was lower than the average (USCB 2000a). 

Table 2-30. Regional Housing Information by County for the Year 2000 

County 

Total 

Housing Unit Occupied 

Owner 

Occupied 

Renter 

Occupied 

Vacant 

Housing 

Percent 

Vacancy 

Brazoria 90,628 81,954 60,674 21,280 8674 9.6% 

Calhoun 10,238 7442 5417 2025 2796 27.3% 

Jackson 6545 5336 3936 1400 1209 18.5% 

Matagorda 18,611 13,901 9282 4619 4710 25.3% 

Total 126,022 108,633 79,309 29,324 17,389 13.8% 

Source: USCB 2000a 

Of 4710 vacant housing units in Matagorda County in 2000, 685 were for rent and 244 were for 

sale. Also, of the 4710 vacant units, 709 were mobile homes and 224 were in the category of 

RVs, boats, vans, etc. Of 8674 vacant housing units in Brazoria County, 3168 were for rent and 

984 were for sale. Of the 8674 vacant units, 1535 were mobile homes and 176 were in the 

category of RVs, boats, vans, etc (STPNOC 2010a). Of 2796 vacant housing units in Calhoun 

County in 2000, 385 were for rent and 114 were for sale. Also, of the 1209 vacant units, 518 

were mobile homes and 38 were in the category of RVs, boats, vans, etc. Of 1209 vacant 

housing units in Jackson County in 2000, 256 were for rent and 67 were for sale. Also, of the 

2796 vacant units, 204 were mobile homes and 14 were in the category of RVs, boats, vans, 

etc. (USCB 2000b, c, d, e, f, g). A total of 5903 vacant housing units were available for sale or 

rent in the two counties. 

Vacant housing units for seasonal, recreational, or occasional use were approximately 2407 in 

Matagorda County, 1496 in Brazoria County, 1751 in Calhoun County and 228 in Jackson 

County. Hotel/Motel data for the four-county socioeconomic impact area in 2006 is presented in 

Table 2-20 (STPNOC 2010a; USCB 2000b, c, d, e, f, g). There were approximately 1099 hotel 

rooms per night available with an average occupancy of about 54 percent. 
Affected Environment 

NUREG-1937 2-134 February 2011 

2.5.2.6 Public Services 

Water Supply and Waste Treatment 

The STP site consumed 422 million gallons of water in 2005 from five onsite groundwater wells. 

Approximately five percent of this water was used for sanitary and drinking uses. From 2001 

through 2006 STP used approximately 1.1 million gallons per day (MGD) on average for all 

purposes pertaining to existing STP Units 1 and 2. The STP site is permitted to withdraw an 

average of 2.7 MGD (STPNOC 2010a). 

Water assessment and planning in Texas is performed on a regional basis rather than a county 

or city basis and all four counties in the socioeconomic impact area are in different planning 

regions. Each region is made up of several different counties and is represented by a Regional 

Water Planning Group, composed of representatives from a variety of interests that prepares a 

regional water plan for the region. Matagorda County is in Region K. Brazoria County is 

located in Region H, which also includes the City of Houston. Calhoun County is located in 

Region L (includes San Antonio) and Jackson County is located in Region P. Below is a brief 

overview of each region’s water issues from 2010 to 2060. More information on surface water 

and groundwater issues can be found in Section 2.3. 

Region K’s population is projected to increase nearly 100 percent between 2010 and 2060 to 

2.7 million people (representing 5 percent of the projected Texas population); however, water 

demands are not projected to increase as significantly. Water demand in 2060 for Region K is 

expected to be about 1.3 million ac-ft, up slightly from the 2010 level of about 1.1 million ac-ft. 

The Colorado River and its tributaries are the primary surface water supply sources and five 

primary aquifers provide groundwater supplies. Due to reservoir sedimentation and expired 

water supply contracts, Region K expects its total water supply to decrease from 1.18 million 

ac-ft in 2010 to 888,000 ac-ft in 2060. Water demand would be 400,000 ac-ft more than water 

supply. However, water management strategies for Region K are expected to provide 

860,000 ac-ft of additional water supply by 2060. Water management strategies for Region K to 

meet 2060 demand include reuse, seawater desalination, conservation and the LCRA-SAWS 

Water Project. The LCRA-SAWS Water Project includes off-channel reservoirs, agricultural 

water conservation, additional groundwater development, and new and/or amended surfacewater rights (STPNOC 2010a). 

Region H population is expected to represent 23 percent of the State’s population in 2010 

(5.8 million people) and increase 89 percent to 10.9 million people in 2060. Total water demand 

is projected to be 2.3 million ac-ft in 2010 and 3.4 million ac-ft in 2060. Total water supply is 

projected to decrease due to reduced supplies in the Gulf Coast Aquifer because of district 

subsidence regulations from 2.71 million ac-ft in 2010 to 2.56 million ac-ft in 2060. Region H 
Affected Environment 

February 2011 2-135 NUREG-1937 

plans to meet the 2060 deficit of 800,000 ac-ft using several water management strategies 

including reuse, seawater desalination and conservation. These strategies are expected to 

provide 1.3 million ac-ft of water by 2060 (STPNOC 2010a). 

Although Region L population is expected to increase approximately 75 percent between 2010 

and 2060, water demand is expected to increase less dramatically. Water demand is projected 

to increase from 985,000 ac-ft in 2010 to 1.27 million ac-ft in 2060, while year 2060 water 

supplies are projected to be 1.02 million ac-ft. Region L water management plans to 

compensate for this deficit include coordinated use of surface water and groundwater, reuse, 

groundwater and seawater desalination, conservation and the LCRA-SAWS Water Project. 

These strategies are expected to provide 730,000 ac-ft of additional water by 2060 (TWDB 

2006c). 

Region P population is expected to remain relatively stable between 2010 and 2060 (less than 

50,000). Water demand is expected to decrease slightly during that same period. Region P is 

projected to see a decrease in water demand from 226,000 ac-ft in 2010 to 207,000 ac-ft in 

2060. The total water supply is estimated to remain constant at 209,000 ac-ft per year 

throughout the 2010 to 2060 time period. Region P is expected to meet their 2010 deficit by 

pumping additional groundwater during the irrigation season, then allowing water levels to 

recover. Water management plans for Region P include conservation for municipal users only, 

the continued use of good agricultural practices, and fees for groundwater export out of the 

region (TWDB 2006a). 

Table 2-31 describes water suppliers in the four-county socioeconomic impact area, their 

current capacities, and their average daily production. Currently, there is excess production 

capacity in water supply facilities. 

Local governments provide wastewater treatment and TCEQ regulates it. Plant capacity is 

based on an average usage over a period of time and therefore, short-term usage may exceed 

the overall capacity (STPNOC 2010a). Once a plant has exceeded 75 percent of permitted 

average daily or annual average flow for three consecutive months, the permitted plant must 

begin engineering and financial planning for expansion/upgrades of the facility. Once the facility 

reaches 90 percent of permitted average daily flow for three straight months, it must obtain 

TCEQ authorization to begin building. There are a few systems in the area which have 

occasionally exceeded permitted capacity, but none that have done so for 3 months in a row. 

Table 2-32 details public wastewater treatment facilities in the socioeconomic impact area, the 

average flow rates for their plant designs, and their average monthly processing. The rural 

areas of each county are on septic systems (STPNOC 2010a). 
Affected Environment 

NUREG-1937 2-136 February 2011 

Table 2-31. Water Supply, Capacity, and Average Daily Consumption by Major Water Supply 

Systems in Brazoria, Calhoun, Jackson, and Matagorda Counties 

System Name 

Population 

Served(a,b) Primary Water Source(b)

Total 

Production 

(MGD)(c)

Max 

Purchased 

Capacity 

(MGD)(c)

Average Daily 

Consumption 

(MGD)(c)

Brazoria County 

City of Alvin 17,916 Groundwater 8.739 4.75 1.307 

City of Angleton 19,167 Purchased Surface Water 5.112 2.016 1.91 

City of Clute 13,836 Purchased Surface Water 2.08 0 0.361 

City of Freeport 25,058 Purchased Surface Water 0 2 1.4 

City of Lake Jackson 25,890 Purchased Surface Water 6.696 2 3.1 

City of Pearland 56,877 Purchased Surface Water 13.54 0 3.14 

County Subtotal 158,744 36.167 11.218 

Calhoun County 

Calhoun County Rural 

Water System 3705 Purchased Surface Water 2.26 0 0.205 

City of Point Comfort 2751 Surface Water 1.152 0 0.128 

City of Port Lavaca 13,269 Purchased Surface Water 0 2 1.14 

City of Seadrift 2331 Groundwater 2.304 0 0.104 

Port O’Connor MUD 3810 Purchased Groundwater 1.044 0 N/A 

County Subtotal 25,866 6.76 1.577 

Jackson County 

City of Edna 5899 Groundwater 3.16 0 0.544 

City of Ganado 1847 Groundwater 2.923 0 0.199 

Jackson County WCID 1 741 Groundwater 0.346 0 0.047 

Jackson County WCID 2 480 Groundwater 0.324 0 0.057 

County Subtotal 8967 6.753 0.847 

Matagorda County 

City of Bay City 19,263 Groundwater 8.856 4.403 2.409 

City of Palacios 5100 Groundwater 1.973 1.224 0.542 

County Subtotal 24,363 10.829 2.951 

Sources: STPNOC 2010a; EPA 2008; TCEQ 2008b 

(a) Data selected based on major populations served per county. Year of data not provided. Data extracted from 

TCEQ database that is updated continuously. 

(b) EPA 2008. 

(c) TCEQ 2008b. 

WCID = Water Control and Improvement District. MUD = Municipal Utilities Department. 
Affected Environment 

February 2011 2-137 NUREG-1937 

Table 2-32. Designed Capacity and Maximum Water Treated in Wastewater Treatment 

Systems in Brazoria, Calhoun, Jackson, and Matagorda Counties 

System Name 

Plant 

Designed 

Average 

Flow 

(MGD) 

Average 

Wastewater 

Processed 

(MGD) Time Period 

Brazoria County 

Oak Manor MUD 0.080 0.026 January 2006 – December 2006 

City of Sweeny 0.975 0.396 January 2006 – December 2006 

City of Alvin 5.000 2.396 January 2006 – December 2006 

Commodore Cove Improvement District 0.060 0.024 January 2006 – December 2006 

City of Brazoria 0.750 0.422 January 2006 – December 2006 

City of Lake Jackson 4.000 2.868 January 2006 – December 2006 

City of West Columbia 1.600 0.646 January 2006 – December 2006 

Brazoria County FWSD No. 1 0.140 0.034 January 2006 – December 2006 

City of Pearland (STP No. 2) 3.100 1.517 January 2006 – December 2006 

City of Pearland (STP No. 3) 1.750 1.692 January 2006 – December 2006 

City of Freeport 2.250 0.839 January 2006 – December 2006 

City of Freeport 0.300 0.008 January 2006 – December 2006 

City of Clute 4.000 2.713 January 2006 – December 2006 

City of Hillcrest Village 0.150 0.082 January 2006 – December 2006 

City of Angleton 3.600 1.465 January 2006 – December 2006 

City of Angleton 0.250 0.093 January 2006 – December 2006 

City of Danbury 0.504 0.157 February 2006 – November 2006 

City of Oyster Creek 0.500 0.194 January 2006 – December 2006 

City of Pearland 0.950 0.457 January 2006 – December 2006 

Brazoria County MUD No. 3 2.400 1.064 January 2006 – December 2006 

City of Pearland 2.000 1.394 January 2006 – December 2006 

City of Pearland 0.250 0.341 January 2006 – December 2006 

City of Manvel Outfall 001A and Outfall B 0.100 0.060 January 2006 – December 2006 

Brazoria County MUD 21 0.250 0.125 January 2006 – December 2006 
Affected Environment 

NUREG-1937 2-138 February 2011 

Table 2-32. (contd) 

System Name 

Plant 

Designed 

Average 

Flow 

(MGD) 

Average 

Wastewater 

Processed 

(MGD) Time Period 

Calhoun County 

City of Point Comfort 0.2 0.057 September 2006 – August 2007 

City of Port Lavaca 1.5 1.24 October 2006 – September 2007 

City of Seadrift 0.3 0.15 September 2006 – August 2007 

Port O’Connor MUD 0.6 0.11 September 2006 – August 2007 

Guadalupe-Blanco River Authority 0.03 0.009 September 2006 – August 2007 

South-Central Calhoun County W. 0.075 0.021 August 2006 – July 2007 

Jackson County 

City of Edna 1.8 0.713 September 2006 – August 2007 

City of Ganado 0.35 0.201 September 2006 – August 2007 

City of La Ward 0.013 0.0017 September 2006 – August 2007 

Jackson County WCID No. 1 0.062 0.042 August 2006 – July 2007 

Jackson County WCID No. 2 0.045 0.045 October 2006 – September 2007 

Matagorda County 

City of Palacios 0.800 0.512 January 2006 – December 2006 

Matagorda County WCID No. 6 0.193 0.065 January 2006 – December 2006 

City of Bay City 4.300 2.420 January 2006 – December 2006 

Markham MUD 0.300 0.042 January 2006 – December 2006 

Matagorda County WCID No. 5 0.075 0.046 January 2006 – December 2006 

Beach Road MUD 0.050 0.027 January 2006 – December 2006 

Lower Colorado River Authority 0.025 0.003 August 2006 – December 2006 

Sources: STPNOC 2010a; Exelon 2008 

WCID = Water Control and Improvement District. 

MUD = Municipal Utilities Department. 

N/A = Not Available. 

Police, Fire and Medical 

The Matagorda County Emergency Management Office is the lead agency responsible for 

emergency management planning in Matagorda County and coordinates with both the 

Governor’s Division of Emergency Management and the STP Emergency Response 

Organization when responding to emergencies. Table 2-33 and Table 2-34 provide police and 

fire information for the four county socioeconomic impact area. Emergency management 

officials consider police and fire protection adequate at this time (STPNOC 2010a). 
Affected Environment 

February 2011 2-139 NUREG-1937 

Table 2-33. Law Enforcement Personnel 2005 

Political 

Jurisdiction 

Total Law 

Enforcement 

Employees 

Total 

Police 

Officers(a)

Total 

Civilians(b)

Brazoria County 

Brazoria County 279 164 115 

Alvin 70 43 27 

Angleton 47 36 11 

Brazoria 10 6 4 

Clute 31 22 9 

Danbury 1 1 0 

Freeport 36 27 9 

Lake Jackson 58 43 15 

Manvel 10 8 2 

Oyster Creek 9 5 4 

Pearland 121 91 30 

West Columbia 15 8 7 

Total 687 454 233 

Calhoun County 

Calhoun County 56 22 34 

Point Comfort 1 1 0 

Port Lavaca 25 19 6 

Seadrift 2 2 0 

Total 84 44 40 

Jackson County 

Jackson County 24 14 10 

Edna 11 9 2 

Ganado 4 3 1 

Total 39 26 13 

Matagorda County 

Matagorda County 70 40 30 

Bay City 45 33 12 

Palacios 20 15 5 

Total 135 88 47 

Total All Counties 945 612 333 

Source: FBI 2006 

(a) Individuals who ordinarily carry a badge and a firearm and have full 

arrest powers. 

(b) Personnel such as clerks, radio dispatchers, stenographers, jailers, 

and mechanics. 
Affected Environment 

NUREG-1937 2-140 February 2011 Table 2-34. Fire Protection Personnel(a) Fire Dept Name Dept Type Number of Stations Active Firefighters (Career) Active Firefighters (Volunteer) 

Active 

Firefighters 

(Paid per 

Call) 

Non 

Firefighting 

(Civilian) 

Non 

Firefighting 

(Volunteer)

Brazoria County Alvin Volunteer Fire Department Volunteer 2 0 65 0 2 0 Angleton Fire Department Volunteer 3 0 34 0 0 0 Brazoria Fire Dept Volunteer 1 0 26 0 0 0 Brookston Volunteer Fire Department Volunteer 1 0 10 0 0 2 Clute Volunteer Fire Department Volunteer 2 0 31 0 0 1 Columbia Lakes Volunteer Fire Department Volunteer 1 0 16 0 0 0 County Road 143 Volunteer Fire Department Volunteer 1 0 12 0 0 4 Damon Volunteer Fire Department Volunteer 1 0 12 0 0 4 Demi-John Volunteer Fire Department Volunteer 1 0 16 0 0 6 Freeport Fire Department Mostly Volunteer 2 9 15 0 0 0 Iowa Colony Volunteer Fire Department Volunteer 1 0 16 0 0 5 Jones Creek Volunteer Fire Department Volunteer 1 0 20 0 0 0 Lake Jackson Volunteer Fire Department Volunteer 2 0 52 0 0 5 Liverpool Volunteer Fire Department Volunteer 1 0 12 0 0 6 Manvel Volunteer Fire Department Volunteer 2 0 23 5 0 0 Old Ocean Volunteer Fire Department Volunteer 2 0 14 0 0 0 Pearland Volunteer Fire Department Volunteer 4 0 55 0 0 0 River’s End Volunteer Fire Department Volunteer 1 0 10 0 0 20 Rosharon Volunteer Fire Department Volunteer 1 0 14 0 0 0 Surfside Volunteer Fire Department Mostly Volunteer 1 1 8 0 0 5 Sweeny Fire and Rescue Volunteer 1 0 30 0 0 10 The Danbury Volunteer Fire Department Volunteer 1 0 14 0 1 0 Wild Peach Volunteer Fire Department Volunteer 1 0 21 0 0 0 
February 2011 2-141 NUREG-1937 

 Affected Environment Table 2-34. (contd) Fire Dept Name Dept Type Number of Stations Active Firefighters (Career) Active Firefighters (Volunteer) 

Active 

Firefighters 

(Paid per 

Call) 

Non 

Firefighting 

(Civilian) 

Non 

Firefighting 

(Volunteer)

Calhoun County Magnolia Beach Volunteer Fire Department Volunteer 1 0 11 0 0 2 Olivia-Port Alto Volunteer Fire Department Volunteer 1 0 20 0 0 0 Port Lavaca Fire Department Mostly Career 2 16 11 0 1 0 Port O’Connor Volunteer Fire Department Volunteer 1 0 20 0 0 10 Seadrift Volunteer Fire Department Volunteer 1 0 15 0 0 2 Thomaston Volunteer Fire Department Volunteer 1 0 8 0 0 12 Jackson County Edna Fire Department Mostly Volunteer 1 8 22 0 1 0 Ganado Volunteer Fire Department Volunteer 1 0 0 26 0 0 La Ward Volunteer Fire Department Volunteer 1 0 15 0 0 3 Matagorda County Bay City Volunteer Fire Department Volunteer 1 0 46 0 0 0 Blessing Voluntary Fire Department Volunteer 1 0 12 0 0 0 Carancahua Volunteer Fire Department Volunteer 1 0 12 0 0 8 Markham Volunteer Fire Department Volunteer 1 0 20 0 0 5 Matagorda Volunteer Fire Department Volunteer 2 0 22 0 0 25 Midfield Volunteer Fire Department Volunteer 1 0 17 0 0 25 Palacios Volunteer Fire Department Volunteer 2 0 25 0 0 0 Van Vleck Volunteer Fire Department Volunteer 1 0 8 0 0 0 Total All Counties 54 34 810 31 5 160Source: USFA 2008 (a) Data is from the U.S. Fire Administration National Fire Department Census. Responses are voluntary and the USFA estimates that, as of 

2008, approximately 85% of the nation’s fire departments have responded. 
Affected Environment 

NUREG-1937 2-142 February 2011 

Table 2-35 presents hospital use and medical practitioner data by county. There are a total of 

eight hospitals in the four county socioeconomic impact areas. Four of those hospitals are in 

Brazoria County, with over 213 beds and 766 physicians. Calhoun and Jackson counties each 

have one hospital with 25 and 54 staffed beds and 20 and 4 doctors respectively. Matagorda 

County has two hospitals with 83 staffed beds and at least 41 doctors. 

Table 2-35. Hospital Data for Brazoria, Calhoun, Jackson and Matagorda Counties

Facility Name 

Staffed 

Beds 

Admissions

(a)

Census 

(b)

Outpatient 

Visits (a)

Personnel 

(c)

No. of 

Physicians

Brazoria County 

Alvin Diagnostic and Urgent Care Center NA NA NA NA NA NA 

Angleton Danbury Medical Center 43 2385 21 46,745 257 NA 

Brazosport Regional Health System 156 5812 61 107,883 491 NA 

Sweeny Community Hospital 14 274 2 15,560 123 NA 

Total 213 8471 84 170188 871 766 

Calhoun County 

Memorial Medical Center 25 1385 13 29,674 349 NA 

Total 25 1385 13 29674 349 20 

Jackson County 

Jackson County Hospital District 54 403 32 NA 108 NA 

Total 54 403 32 NA 108 4 

Matagorda County 

Matagorda County General Hospital 66 2222 21 34,912 329 NA 

Palacios Community Medical Center 17 391 2 5846 27 NA 

Total 83 2613 23 40,758 356 41 

Total All Counties 375 12872 152 240,620 1684 831

Sources: STPNOC 2010a and Exelon 2008 

(a) Total during a recent 12-month period. 

(b) Average daily census during a recent 12-month period. 

(c) Hospital personnel list does not include doctors that serve patients in the hospital, but are not employed by the 

hospital. 

NA – Not Available. 

Low-income residents are able to access low-cost medical care through two organizations in 

Matagorda County: the Matagorda County Hospital District Public Health Clinic (Public Health 

Clinic) and the Matagorda Episcopal Health Outreach Program. The Public Health Clinic is a 

county organization that assists residents through three programs: the Indigent Care Program, 

the Low-Income Program, and Reduced Rates for the Uninsured Program. The Matagorda 

Episcopal Health Outreach Program is funded and operated by a faith-based non-governmental 

organization and provides mobile medical services to low-income and uninsured populations. 

Low-income residents in Brazoria, Calhoun, and Jackson counties are able to access low-cost 

care from the County Health Department (STPNOC 2010a). 
Affected Environment 

February 2011 2-143 NUREG-1937 

Social services in the four-county socioeconomic impact area are provided by State and local 

governmental and non-governmental organizations. The United Way helps support many 

organizations in the four counties. STPNOC employees have been active in many of these 

same organizations. The primary State-level organization that provides social services is the 

Texas Health and Human Services Commission. The Commission oversees the Department of 

Aging and Disability Services, the Department of Assistive and Rehabilitative Services, the 

Department of Family and Protective Services, and the Department of State Health Services, 

which, collectively, provide the following services: Medicaid, Children’s Health Insurance 

Program, Temporary Assistance for Needy Families, Food Stamps and Nutritional Programs, 

Family Violence Services, Refugee Services, and Disaster, Assistance (STPNOC 2010a). 

Table 2-36 shows the list of United Way agencies in Matagorda County, together with their 

client bases and their funding. 

Education 

A total of 17 school districts with 136 schools supported a 2005-2006 student enrollment of 

69,709 (Table 2-37) (NCES 2008) in the socioeconomic impact area. In addition, there are 

12 private schools with a 2005-2006 student enrollment of approximately 1496 students. There 

are two colleges approximately 50 mi from the STP site (STPNOC 2010a). The public school 

systems in the four-county socioeconomic impact area are organized into ISDs. Table 2-37 and 

Table 2-38 provide summary data on the public and private schools, respectively, in the fourcounty socioeconomic impact area. 

Brazoria County has the largest number of school districts and the most expansion, because 

Houston is encroaching on it. Alvin ISD expects its population to double in the next 10 years. 

Local school officials at Angleton ISD stated they would have extra capacity with the new 

construction and renovation plans currently underway and Columbia-Brazoria ISD stated they 

already have extra capacity. Bay City ISD is likely to be impacted more than other districts due 

to the proximity of the STP site. Local officials at Bay City ISD stated that facilities currently are 

adequate and that they have a new high school, though they also note that, depending on the 

age and location of in-migrating children, portable buildings may be needed (Scott and 

Niemeyer 2008). Capacity data were not available on the private schools in the socioeconomic 

impact area, although student–teacher ratios were available. Private schools do not have the 

same obligation to serve as public schools, so their prospective enrollment levels and capacities 

are more optional. Brazosport College awards both Baccalaureate and Associate Degrees and 

is approximately 54 mi from STP in Lake Jackson, Texas. The college’s 2007 enrollment in 

both credited and non credit courses was 34,484 (Brazosport College 2008). Wharton County 

Junior College awards Associate Degrees. The main campus, which had a 2006 enrollment of 

6089, is located approximately 55 mi from STP in Wharton, Texas (STPNOC 2010a). A branch 

campus of Wharton County Junior College opened in Bay City in 2008. Due to the current 

aging workforce at nuclear power plants and the expansion of the STP plant, the branch 

campus offers a program in Nuclear Power Technology (WCJC 2008). 
Affected Environment 

NUREG-1937 2-144 February 2011 

Table 2-36. United Way Agencies of Matagorda County 

Matagorda County United 

Way Agencies 

Number of 

Clients Last 

Fiscal Year 

% Budget 

from 

United 

Way for 

2001 

$ Received From 

United Way & 

Grants Received 

Using United Way 

Funding as 

Matching Funds 

% of Budget 

From United 

Way & 

Grants 

Matched by 

United Way 

Funds 

Matagorda County United Way 

& HELPLINE 

9000 100% $30,000 100% 

American Red Cross- Bay City 

Chapter 

17,000 45% $49,500 51% 

Association for Retarded 

Citizens 

69 48% $31,000 48% 

Bay City Day Care 400 7% $32,500 10% 

Bay City Community/ Salvation 

Army Food Pantry 

9000 32% $4500 32% 

Boy Scouts 1132 1% $10,000 1% 

Boys & Girls Club-Palacios 369 19% $46,000 95% 

Caring & Sharing Food Pantry 10,332 26% $12,000 53% 

Court Appointed Special 

Advocates 

746 16% $93,900 99% 

Council on Substance Abuse 1321 3% $473,454 99% 

DARE-BCISD 2000 3% $1000 3% 

DARE-TISD 600 3% $1000 3% 

Economic Actions Committee 2043 

utilities/nutrition 

8% $45,617 12% 

4-H Marine---Sea Masters 142 25% $1000 25% 

Friends of Elder Citizens 425 daily meals 9% $423,000 76% 

Girl Scouts 224 1% $9500 1% 

Kids in Distress 25 79% $11,695 84% 

Literacy Volunteers of America 62 30% $34,500 100% 

Matagorda Episcopal Hospital 

Outreach Program 

2657 6% $68,862 24% 

Rainbow Land Day Care 70 daily 23% $55,580 100% 

Salvation Army - Bay City 

Service Unit 

1228 10% $29,757 25% 

Teen Court 1685 19% $85,000 100% 

Women’s Crisis Center 1600 6% $510,793 91% 

Total Dollars Received $2,060,158 

Source: Matagorda County United Way, as reported in STPNOC 2008e 
Affected Environment 

February 2011 2-145 NUREG-1937 

Table 2-37. Public School Statistics in the Four-County Socioeconomic Impact Area, 

2005-2006

 Schools Students 

Student 

Teacher Ratio Capacity 

Available 

Capacity 

Brazoria County 

Alvin ISD 20 13,266 15.7 (a) (b) 

Angleton ISD 13 6444 16.1 8700 2300 

Brazosport ISD 21 13,260 15.9 13,043+ (b) 

Columbia-Brazoria ISD 6 3056 15.2 3450 to 3600 400–500 

Damon ISD 2 164 12.2 164 0 

Danbury ISD 4 759 13.4 Not available (c) 

Pearland ISD 21 15,543 17 19,500 4000 

Sweeny ISD 4 2086 15.2 2,300+ 200+ 

Calhoun County 

Calhoun County ISD 9 4326 16 Not available Not available 

Jackson County 

Edna ISD 5 1472 13.5 Not available (d) 

Ganado ISD 2 658 11.8 Not available Not available 

Industrial ISD 4 989 11.5 Not available Not available 

Matagorda County 

Bay City ISD 8 4140 14 4600 500 

Matagorda ISD 1 56 7 112 56 

Palacios ISD 6 1638 13.9 Not available (e) 

Tidehaven ISD 5 889 11.9 1050 161 

Van Vleck ISD 5 963 12 Not available Not available 

Total 136 69,709 - 

Sources: NCES 2008; STPNOC 2010a 

(a) Student population expected to nearly double in the next 10 years. Extensive building development program is 

underway. 

(b) Some excess capacity once ongoing building program completed. 

(c) District is in the process of preparing a facilities study. New construction expected in the next 5 years. 

(d) District just completed construction of a new elementary school. 

(e) District is in the process of preparing a facilities study. 

STPNOC has partnered with community leadership, ISD leaders, educators, colleges, business 

owners, and other industry in the development of a community- and regional-based education 

alliance called the Gulf Coast Industry Education Alliance. Their goal is to have a “Grow Your 

Own” community-based workforce. They are accomplishing this by working with the region’s 

middle schools and high schools to get students in the right classes for a career in nuclear 

energy. The Alliance also works with State and national funding agencies to identify available 

funds for expanding existing laboratories, developing student skills, and attracting and retaining 

teachers (STPNOC 2010a). 
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Table 2-38. Private School Statistics in the Four-County Socioeconomic Impact Area, 2005-2006 

Private School Location 

Grade 

Levels Enrollment 

Student/ 

Teacher 

Ratio 

Brazoria County 

Brazosport Christian School Lake Jackson pK-12 293 9.7 

Carden-Jackson School Pearland pK-8 118 8.7 

Columbia Christian School West Columbia pK-12 88 8.6 

Hope Christian Learning Center Pearland 8-12 7 7 

Living Stones Christian School Alvin K-12 207 9.7 

Montessori School of DT Pearland pK-1 63 12.7 

Our Lady Queen of Peace Catholic School Richwood pK-8 311 9.5 

Pearland Heritage Christian Academy Monaville K-7 26 6.5 

St. Helen Catholic School Pearland K-8 249 17.2 

Sweeny Christian School Sweeny pK-5 67 10.5 

Calhoun County 

Our Lady of the Gulf Catholic School Port Lavaca K-8 67 NA(a)

Jackson County 

None 

Matagorda County 

Holy Cross School Bay City pK-6 133 12.4 

Total 1496 

Source: STPNOC 2008a 

(a) This information is not available. 

2.6 Environmental Justice 

Environmental justice refers to a Federal policy established under Executive Order 12898 that 

requires each Federal agency to identify and address, as appropriate, disproportionately high 

and adverse human health or environmental effects of its programs, policies, and activities on 

minority or low-income populations (59 FR 7629).(a) The Council on Environmental Quality has 

provided guidance for addressing environmental justice (CEQ 1997). Although it is not subject 

to the Executive Order, the Commission has voluntarily committed to undertake environmental 

justice reviews. On August 24, 2004, the Commission issued its policy statement on the 

treatment of environmental justice matters in licensing actions (69 FR 52040). 

 

(a) Minority categories are defined as: American Indian or Alaskan Native; Asian; Native Hawaiian or 

other Pacific Islander; Black races; or Hispanic ethnicity; “other” may be considered a separate 

minority category. Low income refers to individuals living in households meeting the official poverty 

measure. To see the US Census definition and values for 2000, visit the US Census website at: 

http://ask.census.gov/. 
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February 2011 2-147 NUREG-1937 

This section describes the existing demographic and geographic characteristics of the proposed 

site and its surrounding communities. It offers a general description of minority and low-income 

populations within the 50-mi region surrounding the site. The characterization in this section 

forms the analytical baseline from which the determination of potential environmental justice 

effects would be made. The characterization of populations of interest includes an assessment 

of “populations of particular interest or unusual circumstances,” such as minority communities 

exceptionally dependent on subsistence resources or identifiable in compact locations, such as 

Native American settlements. 

2.6.1 Methodology 

The review team first examined the geographic distribution of minority and low-income 

populations within 50 mi of the STP site, employing a geographic information system and the 

2000 Census to identify minority and low-income populations. The review team verified its 

analysis by field inquiries to numerous agencies and groups (Appendix B). 

The first step in the review team’s environmental justice methodology is to examine each 

census block group that is fully or partially included within the 50-mi region to determine for 

each block group whether the percentage of any minority or low-income population is great 

enough to identify that block group as a minority or low-income population of interest. If either 

of the two criteria discussed below is met for a census block group, that census block group is 

considered a minority or low-income population of interest warranting further investigation. The 

two criteria are whether: 

• the population of interest exceeds 50 percent of the total population for the block group or 

• the percentage of the population of interest is 20 percent (or more) greater than the same 

population’s percentage in the census block group’s State. 

The identification of census block groups that meet the above two part criteria is not in and of 

itself sufficient for the review team to conclude that disproportionately high and adverse impacts 

exists. Likewise, the lack of census block groups meeting the above criteria cannot be 

construed as evidence of no disproportionately high and adverse impacts. Accordingly, the 

review team also conducts an active public outreach and on-the-ground investigation in the 

region of the plant to determine whether minority and low-income populations may exist in the 

region that are not identified in the census mapping exercise. To reach an environmental justice 

conclusion, starting with the identified populations of interest, the review team must investigate 

all populations in greater detail to determine if there are potentially significant environmental 

impacts that may have disproportionately high and adverse effects on minority or low-income 

communities. To determine whether disproportionately high and adverse effects may be 

present, the review team considers the following: 
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NUREG-1937 2-148 February 2011 

Health Considerations 

 1. Are the radiological or other health effects significant or above generally accepted 

norms? 

 2. Is the risk or rate of hazard significant and appreciably in excess of the general 

population? 

 3. Do the radiological or other health effects occur in groups affected by cumulative or 

multiple adverse exposures from environmental hazards? 

Environmental Considerations 

 4. Is there an impact on the natural or physical environment that significantly and adversely 

affects a particular group? 

 5. Are there any significant adverse impacts on a group that appreciably exceed or [are] 

likely to appreciably exceed those on the general population? 

 6. Do the environment effects occur in groups affected by cumulative or multiple adverse 

exposure from environmental hazard? (NRC 2007a) 

If this investigation in greater detail does not yield any potentially disproportionate and adverse 

impacts on populations of interest, the review team may conclude that there are no 

disproportionately high and adverse affects. If, however, the review team finds any potentially 

disproportionate and adverse effects, the review team would fully characterize the nature and 

extent of that impact and consider possible mitigation measures that may be used to lessen that 

impact. The remainder of this section discusses the results of the search for potentially affected 

populations of interest. 

Minority Populations: Census data for Texas characterizes 11.5 percent of the population as 

Black, 0.6 percent as American Indian or Alaskan Native, 2.7 percent as Asian, 0.1 percent as 

Native Hawaiian or other Pacific Islander, 11.7 percent as some other race, 2.5 percent as 

multiracial, 29 percent aggregate of minority races and 32 percent as Hispanic ethnicity 

(STPNOC 2010a). Total minorities, consisting of all racial minorities plus Hispanic whites, make 

up 52.4 percent of the population. 

Figure 2-27 through Figure 2-30 show the location of all census block groups that meet the 

criteria for any of the minority populations identified for environmental justice purposes, as 

calculated by the review team from the 2000 Census (USCB 2000h). Of the 230 block groups 

within the 50-mi radius of the STP site, the review team identified 19 census block groups that 

have significant Black or African American populations (Figure 2-28). One block group located 

in Matagorda County has a significant Asian population (revealed by STPNOC and review team 

scoping and outreach processes to be predominantly Vietnamese) (Figure 2-29). 

Significant Hispanic populations exist in 30 census block groups in the region (Figure 2-30). 

Ten block groups have significant “some other race” population (all of these block groups are 

also Hispanic), and 71 block groups in the region have significant aggregate minority 

populations (Figure 2-27). 
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February 2011 2-149 NUREG-1937 

Figure 2-27. Aggregate Minority Populations in Block Groups Meeting Environmental Justice 

Selection Criteria (USCB 2000h) 
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Figure 2-28. Black or African American Populations in Block Groups Meeting Environmental 

Justice Selection Criteria (USCB 2000h) 
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Figure 2-29. Asian or Pacific Islander Populations in Block Groups Meeting Environmental 

Justice Selection Criteria (USCB 2000h) 
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Figure 2-30. Hispanic Populations in Block Groups Meeting Environmental Justice Selection 

Criteria (USCB 2000h) 
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February 2011 2-153 NUREG-1937 

Low-Income Populations: The review team used census data to identify low-income 

households within the analytical area (USCB 2000i). The data indicates that 14 percent of 

Texas households are low income. There are six block groups in the STP region with significant 

low-income populations. Three of these block groups are located in Wharton County, two in 

Matagorda County, and one in Brazoria County. The geographic location of the low-income 

block groups is shown in Figure 2-31. 

2.6.2 Scoping and Outreach 

During the development of its ER, STPNOC interviewed community leaders of the minority 

populations within the analytical area (STPNOC 2010a). The review team built upon this base 

and performed additional interviews within the analytical area that had the potential for the 

greatest environmental and socioeconomic effects. The review team interviewed local, State, 

and county officials, business leaders, and key members of minority communities within the four 

county socioeconomic impact area to assess the potential for disproportionate environmental 

and socioeconomic effects that may be experienced by minority and low-income communities 

impacted by building and operating the proposed Units 3 and 4 (STPNOC 2010a; Scott and 

Niemeyer 2008). Advanced notice of public scoping meetings was provided by the review team 

in accordance with NRC guidance. These activities did not identify any additional groups of 

minority or low-income persons not already identified in the geographic information system 

analysis of Census data, except for an isolated community on the banks of the Lower Colorado 

River downstream from the plant that may include significant numbers of low-income individuals 

(although not identified on census maps as either low income or minority) who may be engaged 

in subsistence fishing. 

2.6.3 Subsistence and Communities with Unique Characteristics

For each of the identified low-income and minority populations, it is necessary to determine if 

any of those populations appears to have a unique characteristic at the population level that 

would cause an impact to disproportionately affect them. Examples of unique characteristics 

might include lack of vehicles, sensitivity to noise, close proximity to the plant, subsistence 

activities, or lack of basic health care, but such unique characteristics need to be demonstrably 

present in the population and relevant to the potential environmental impacts of the plant. If the 

impacts from the proposed action would appear to affect an identified minority or low-income 

population more than the general population because of one of these or other unique 

characteristics, then a determination is made whether the impact is disproportionate when 

compared to the general population. Through its review of the applicant’s ER, its own outreach 

and research, and through scoping comments, the review team identified two communities (a 

Vietnamese community at Palacios and a small, potentially low-income community downstream 

from the STP site on the Lower Colorado River) with potentially unique characteristics for further 

considerations within the vicinity of the STP site. The review team assesses the subsistence 

and special characteristics of these populations in Sections 4.5.5 and 5.5.4. 
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NUREG-1937 2-154 February 2011 

Figure 2-31. Aggregate Low-Income Populations in Block Groups Meeting Environmental 

Justice Selection Criteria 
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February 2011 2-155 NUREG-1937 

The review team considered STPNOC’s documented outreach process on environmental justice 

issues (STPNOC 2010a, 2008a) and conducted its own interviews with local officials in Bay City 

and Palacios (Scott and Niemeyer 2008). The review team also considered public comments 

related to the proposed project. Finally, the review team performed literature reviews for 

academic studies and performed internet searches for documented subsistence activities by 

minority and low-income populations. The review team did not find any indications that any 

populations had unique characteristics or practices that could potentially lead to a 

disproportionately high and adverse impact in the Matagorda County area. 

The review team’s outreach and scoping activity did not identify any special socioeconomic 

circumstances or potential environmental pathways. 

2.6.4 Migrant Populations 

The USCB defines a migrant worker as an individual employed in the agricultural industry in a 

seasonal or temporary nature and who is required to be absent overnight from their permanent 

place of residence. From an environmental justice perspective, there is a potential for such 

groups in some circumstances to be disproportionately affected by emissions in the 

environment. However, in the four-county area surrounding the STP site the 2002 Census of 

Agriculture found only 95 out of 1051 farms employing 3026 short-term farm laborers reported 

individuals meeting the definition of migrant farm workers, and only 72 of those farms were 

found in Matagorda County, which would not add many low-income or minority individuals to 

those already present in the resident population, even if all of the migrant workers were minority 

or low-income individuals. Based on the average number of short-term workers per farm in the 

four-county area, the review team estimates that the total number of migrant workers is about 

300 in the four-county area, most of who work in Matagorda County. No information was 

available concerning their actual location of employment within the county. 

2.6.5 Environmental Justice Summary 

The review team found low-income, Black, Hispanic, Asian, some other race, and aggregated 

minority populations that exceed the percentage criteria established for environmental justice 

analyses. Consequently, the review team performed additional analyses before making a final 

environmental justice determination. Based on the information in the STPNOC ER (STPNOC 

2010a), public input, and its own outreach and analysis, the review team determined that 

because there are minority and low-income populations of interest in the region and particularly 

because some of these live in close proximity to the proposed site, impacts to these 

communities must be considered in greater detail, as discussed in Section 2.6.1. The result of 

the review team’s analyses can be found in Section 4.5 for construction effects and Section 5.5 

for operational effects. 
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NUREG-1937 2-156 February 2011 

2.7 Historic and Cultural Resources 

In accordance with 36 CFR 800.8(c), the review team has elected to use the National 

Environmental Policy Act of 1969, as amended (NEPA) process to comply with the obligations 

imposed under Section 106 of the National Historic Preservation Act (NHPA). In addition to 

NUREG-1555 (NRC 2000), NRC Staff Memorandum (NRC 2010) provides guidance to staff on 

cultural and historic resource analysis in its environmental reviews. 

The review team determined that the physical area of potential effect (APE) for the COL review 

is the area at the power plant site and the immediate environs that may be impacted by landdisturbing activities associated with building and operating two new nuclear generating units. 

The visual APE for the STP site is a 1-mi radius from the physical APE, determined by the 

maximum distance from which the tallest structures associated with proposed Units 3 and 4 can 

be seen from offsite locations. 

This section discusses the historic and cultural background in the STP site region. It also 

details the efforts that have been taken to identify cultural resources in the physical and visual 

APEs and the resources that were identified. A description of the consultation efforts is also 

provided. The assessments of effects from building and operating the proposed new units are 

found in Sections 4.6 and 5.6, respectively. 

2.7.1 Cultural Background 

The area in and around the COL site has a rich cultural history and a substantial record of 

significant prehistoric and historic resources. The Colorado River system flows through the area 

and influenced settlement in the area. The archaeological record indicates that prehistoric 

occupation of the area was as follows (Hester 1995; Turner and Hester 1985): 

• Paleoindian (pre-7800 B.C.) – The earliest inhabitants of Texas during the late Pleistocene 

are associated with the Clovis Complex based upon the presence of the Clovis fluted point 

that is commonly found throughout North America. Clovis is commonly associated with 

hunting of the extinct mammoth and other large Pleistocene fauna. The Clovis people either 

were replaced or transitioned to the Folsom Complex, which flourished between 8800 and 

8200 B.C. The hallmark artifact of the Folsom period is the Folsom fluted point, which is 

often found in association with forms of bison that are presently extinct. After Folsom, 

evidence of sites dating to the later stages of the Paleoindian period are identified by a 

range of finely made Paleoindian projectile points. 

• Early Archaic (7800 B.C. to 6000 B.C.) – The Archaic represents a time when people 

became more settled and broadened their use of flora and fauna. While the early phases of 

this period are not well understood, later phases are generally well documented by 

numerous distinctive triangular points and large barbed specimens found across Texas. 
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February 2011 2-157 NUREG-1937 

• Middle Archaic (6000 B.C. to 2500 B.C.) – An increase in the number of archaeological sites 

dating to this period suggests an increase in population. An increase in economic 

complexity is suggested by the greater diversity of stone tools. Regional differentiation 

begins to appear, with sites in South Texas often characterized as shell middens. Burial 

sites begin to appear and exotic items suggesting commercial trade are found. 

• Late Archaic (2500 B.C. to 700 B.C.) – This period is characterized by distinct types of 

projectile points and stone tools, suggesting continued economic diversification and 

regionalization. 

• Late Prehistoric (700 B.C. to 1500 A.D.) – The Late Prehistoric era is marked by the 

introduction of the bow and arrow and pottery. Although the hunting and gathering lifeways 

of the Archaic period continue, distinctive changes in material culture, hunting patterns, and 

other facets of Late Prehistoric settlement and subsistence do occur and reflect a change 

from previous periods. 

The historic period can be traced to the 1500s when the Spanish and French explored the 

Texas Coast (Hall and Ford 1973). At that time, the Native American groups living in the areas 

were collectively known by the Europeans as the Karankawa. The French attempted to settle 

the Matagorda Bay area in 1685 and again in 1718, but neither attempt was successful, largely 

due to conflict with the Karankawa Indians. Historic settlement of the area commenced when 

Stephen F. Austin obtained a grant from the Mexican government in 1821 to permit 300 

American families to settle along the Colorado River. When an additional 3000 families were 

allowed to settle in the area in 1828, population increased rapidly. Matagorda County was 

created in 1837, shortly after Texas gained its independence from Mexico. Farming in the 

Matagorda region concentrated on sugar and cotton production and, following the Civil War, 

cattle ranching. 

2.7.2 Historic and Cultural Resources at the Site 

The following information was used to identify the historic and cultural resources at the STP site: 

• Original Construction FES (NRC 1975), 

• Original Environmental Report (NRC 1975), which included the Texas Archaeological 

Survey Report (Hall and Ford 1973), 

• Original Operation EIS (NRC 1986), 

• South Texas Project Units 3 and 4 Environmental Report, Rev 4 (STPNOC 2010a), 

• Information obtained from the Texas Archaeological Site Files (STPNOC 2010a), and 

• Information obtained from the Matagorda County Museum Archives and Collections 

Department. 
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NUREG-1937 2-158 February 2011 

STPNOC conducted a review of records maintained by the National Park Service and the Texas 

Historical Commission to identify important cultural and historic resources located within 10 mi 

of the project site (STPNOC 2010a). This review identified six Texas Historic Landmarks and 

two Historic Texas cemeteries, all of which were more than 6 mi from STP. One of these 

places, the Matagorda Cemetery, located 9 mi southeast of STP, is the only site listed in the 

National Register of Historic Places located within 10 mi of the project site. A search of the 

Texas Archaeological Research Laboratory at the University of Texas at Austin indicated that 

35 archaeological properties have been identified within 10 mi of the plant, none of which have 

been evaluated for listing in the National Register. Four of these archaeological properties are 

historic sites and are recorded as State archeological landmarks, as maintained by the Texas 

Archaeological Research Laboratory at the University of Texas at Austin; one is a cistern, one is 

a farmstead, one is a refuse scatter, and one is a homestead ruin. The remaining thirty-one 

sites are prehistoric. Of these, three are described as only a projectile point find, five are lithic 

scatters, and twenty-three are shell middens. The majority of prehistoric sites are located in the 

Mad Island WMA more than 7 mi south of the STP site (STPNOC 2010a). 

The number of archaeological sites recorded within 10 mi of the STP site is likely more a 

reflection of the small amount of area that has been archaeologically surveyed than it is a 

reflection of the number of archaeological sites that exist. Regional settlement patterns would 

suggest that prehistoric people lived along the Colorado River and that archaeological evidence 

of their habitation should exist. Few surveys, however, have been conducted along the 

Colorado River in the area adjacent to the plant to confirm this pattern. 

The archaeological sites record search indicated that prehistoric sites, most characterized as 

shell middens, have been located adjacent to the STP site. When the Texas Archaeological 

Survey visited the heavily vegetated STP site in 1973, its investigations included a pedestrian 

surface survey with limited subsurface testing and an historic records search. Survey coverage 

at this time included sufficient acreage to construct two additional reactor units (Hall and Ford 

1973). In December 2006, STPNOC contacted the Texas State Historic Preservation Officer 

(SHPO) and requested an additional review of the STP site under NHPA Section 106 (STPNOC 

2010a). Concurrence was obtained from the State that there would be no impacts to historic 

properties in January 2007 (THC 2007). Therefore, no further cultural resource investigations 

were required by the State. 

When construction of existing STP Units 1 and 2 was completed in the 1980s, much of the plant 

site was extensively disturbed by construction. As documented in aerial photographs, the new 

areas proposed for proposed Units 3 and 4 were disturbed by the existing STP Units 1 and 2 

construction (STPNOC 2010a). 

In 2007, NRG and its cultural resource contractor EarthTech, conducted a reconnaissance-level 

cultural resources assessment of the STP site. They reviewed existing information for the STP 

site and the area within a 10-mi diameter. Based on the literature review, EarthTech concluded 
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February 2011 2-159 NUREG-1937 

that any sites that may have existed onsite would no longer retain their cultural integrity because 

the area was heavily disturbed (STPNOC 2010a). 

During the site visit in February 2008, the NRC staff reviewed the documentation used by the 

applicant to prepare the cultural resource section of the ER. The staff also visited the 

Matagorda County Museum and Archives located in Bay City. According to the Matagorda 

County Museum and Archives, the remains of a circa 1900 farmstead are located on the STP 

site (Rodgers 2008). However, no activity related to building or operating the plant is planned 

for this area. Staff at the Matagorda County Museum and Archives also identified another home 

of historic significance that had previously been located adjacent to and northeast of the STP 

site. The ‘Tadmor,’ an octagon-shaped house constructed in the mid-1800s was a well-known 

local landmark. After years of neglect and inclement weather, the home is no longer standing. 

2.7.3 Consultation 

In January 2008, the NRC initiated consultation on the proposed action by writing the Texas 

SHPO and the Advisory Council on Historic Preservation (NRC 2008b). Also in January 2008, 

the NRC initiated consultations by writing to four Native American Tribes with historical ties to 

the Matagorda Bay coastal region (See Appendix F for complete listing). In the letters, NRC 

provided information about the proposed action, indicated that review under the NHPA would be 

integrated with the NEPA process in accordance with 36 CFR 800.8, invited participation in the 

identification and possible decisions concerning historic properties, and invited participation in 

the scoping process. Similarly, in March 2010, the NRC provided copies of the draft EIS to the 

Texas SHPO, Advisory Council on Historic Preservation, and the four previously contacted 

Tribes and invited comments on the review team’s preliminary determination of no historic 

properties affected by the proposed action. In March 2010, the Texas SHPO concurred with the 

determination of no historic properties affected (THC 2010). In May 2010, the AlabamaCoushatta Tribe of Texas confirmed that the proposed action will cause no known impacts to 

religious, cultural, or historical resources of importance to the Tribe, but requested further 

consultation if an alternative site is selected or in the event of any inadvertent cultural 

discoveries (Celestine 2010). 

On February 5, 2008, as part of its NEPA scoping process, the NRC elected to conduct a public 

scoping meeting in Bay City, Texas. No comments or concerns regarding historic and cultural 

resources were raised at this meeting or in the scoping process. Subsequent to the NRC 

initiating consultation with the Texas SHPO, the Advisory Council, and the Tribes, the Corps 

elected to participate as a cooperating agency with the NRC under the updated Memorandum of 

Understanding between the NRC and the Corps. Public meetings were also held in Bay City, 

Texas, in May 2010 to discuss the analysis and results in the draft EIS and no comments or 

concerns regarding historic and cultural resources were raised.
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NUREG-1937 2-160 February 2011 

2.8 Geology 

A detailed description of the geological, seismological, and geotechnical engineering conditions 

at the STP site is provided in Section 2.5 of the STPNOC FSAR (STPNOC 2010b) as part of the 

COL application. A summary of the long-term and short-term geologic impacts of the proposed 

STP project is addressed in ER Section 2.6 (STPNOC 2010a). A description of the 

hydrogeologic setting of the proposed site is addressed in the ER as well (STPNOC 2010a). 

The regional and site-specific geologic descriptions provided by the applicant as part of the 

safety analysis for this COL application (Section 2.5 of the FSAR) are based on the results of 

field and subsurface investigations conducted during pre-application activities for proposed 

Units 3 and 4 (STPNOC 2010a, b) and the most current published geologic data, in addition to 

the results of the site characterization studies conducted prior to and during construction of 

Units 1 and 2. The NRC staff’s independent assessment of the site safety issues related to the 

proposed STP site will consider the applicant’s detailed analysis and evaluation of geological, 

seismic, and geotechnical engineering data. The NRC staff’s detailed evaluation of the 

applicant’s geological characterization for the STP site will be addressed in the NRC staff’s 

Safety Evaluation Report (in process). 

The STP site is located within the Coastal Plain physiographic province which forms a broad 

band parallel to the Texas Gulf Coast (Ryder 1996) which is also described as the Gulf Coastal 

Plains physiographic province by the Bureau of Economic Geology research unit at the 

University of Texas at Austin (TBEG 1996). The STP site lies in the Coastal Prairies subprovince of this physiographic province and exhibits a relatively flat topography with land 

elevation ranging from sea level on the coast to 300 ft above sea level along the western 

boundary of the province (TBEG 1996). The land surface elevation in the immediate vicinity of 

the STP site is 30 ft above MSL. Figure 2-16 shows the stratigraphic column that represents 

the geology beneath the STP site. 

For the purposes of considering the hydrogeological setting in the vicinity of the STP intake 

structure on the Colorado River, an apparent feature is the incision in the sediments by the river 

to an elevation of approximately 14 ft below MSL (STPNOC 2010a). At the nearby STP site, 

this would imply direct communication between the Colorado River and the Upper Shallow 

Aquifer (STPNOC 2010a). 

Within the Coastal Prairies physiographic sub-province, the STP site is located within the 

Coastal Lowlands Aquifer System (TBEG 1996) which is comprised of a wedge of southeasterly 

dipping sedimentary deposits of Holocene age through Oligocene age. The thickness of the 

aquifer ranges from 0 ft at the up-dip limit of the aquifer system in the northwest to 

approximately 1000 to 2000 ft in Matagorda County at the down-dip limit of the system in the 

southeast. Sediments in the Coastal Lowlands Aquifer System varies from zero at the western 

boundary, where it is in contact with the Vicksburg-Jackson confining unit at the land surface, to 
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February 2011 2-161 NUREG-1937 

as much as 6000 ft below sea level where the base of the aquifer is defined by groundwater 

with a dissolved-solids concentration of more than 10,000 milligrams per liter (Ryder 1996). 

Within Texas, the Coastal Lowlands Aquifer System in the vicinity of the STP site, part of the 

Gulf Coast Aquifer system, has not been declared a sole source aquifer by the Environmental 

Protection Agency (EPA 2009a, b, c). 

Within Matagorda County, there are approximately 368 active oil and gas wells; 120 oil and 

248 gas wells (TRC 2009a, b, c); active energy exploration is ongoing in the region. Of these 

wells, STPNOC noted that there are seven petroleum wells, nine oil/gas wells, and 26 gas wells 

in the site vicinity (STPNOC 2010a). In Texas, subsurface mineral rights may be separate from 

surface land ownership rights. Co-owners of STP own or control all of the mineral interests 

within and underlying the STP site, and have the ability to acquire any outstanding mineral 

interests in the subsurface that may be required for safe operation of the facility (STPNOC 

2010a). In addition to oil and gas exploration, numerous byproducts of the refining process are 

also extracted and made commercially available by chemical producers in Matagorda County, 

(i.e., OXEA Corporation’s Bay City Plant and Lyondell Chemical Company’s Equistar facility). 

The USGS mineral industry survey for sand and gravel producers (USGS 2008) did not identify 

principal producers of construction sand and gravel in Matagorda County, Texas. The USGS 

did not identify principal producers of crushed stone in Matagorda County (USGS 2009d). The 

source or sources of sand and gravel for the backfill and concrete necessary to construct 

proposed Units 3 and 4 are not identified (STPNOC 2010b). However, the applicant states that 

the bulk of the structural fill will come from offsite sources. Structural fill for existing STP Units 1 

and 2 was obtained from the Eagle Lake/Gifford Hill source which is approximately 55 mi north 

of the STP site (STPNOC 2010b). 

2.9 Meteorology and Air Quality 

The following sections describe the climate and air quality of the STP site. Section 2.9.1 

describes the climate of the region and area in the immediate vicinity of the STP site, 

Section 2.9.2 describes the air quality of the region, Section 2.9.3 describes atmospheric 

dispersion at the site, and Section 2.9.4 describes the meteorological monitoring program at 

the site. 

2.9.1 Climate 

The STP site is located in Matagorda County, near the Gulf of Mexico in the southeastern 

portion of Texas. Its climate, which is classified as maritime subtropical, is marked by relatively 

short, mild winters, long, hot summers, and mild springs and falls. The Azores high-pressure 

system is the source of maritime tropical air masses much of the year. Occasional cold 

continental air masses displace the maritime air during the winter. 
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NUREG-1937 2-162 February 2011 

The closest first-order National Weather Service station is Victoria, Texas, about 53 mi west of 

the site. This station represents the general climate at the STP site. The National Weather 

Service (NWS) station at Corpus Christi, Texas, about 100 mi southwest is also representative 

of the site, and is more indicative of the diurnal variation of weather at the site because of its 

proximity to the coast. Representative meteorological data have also been collected at the 

Palacios Municipal Airport about 13 mi west southwest of the site. In subsequent sections, the 

review team relies on the climatological and storm characteristics for these sites in estimating 

long-term characteristics for the STP site. 

The following climatological statistics are derived from local climatological data for Palacios, 

Victoria, and Corpus Christi. Temperatures are more variable in the winter than in the summer 

because of the differences in air mass source regions. Daytime maximum temperatures range 

from about 65°F in January to about 94°F in July and August; nighttime minimum temperatures 

range from about 47°F in January to about 75°F in July and August. Monthly average wind 

speeds range from about 10 mph in September to about 14 mph in March and April. 

Precipitation ranges from about 2 in. per month in February peaking to about 4 to 5 in. per 

month in May and June and again in September and October. Snow occurs during more than 

50% of the winters, but snowfall is generally limited to trace amounts. The STP site is flat with 

no topographic features that would cause the local climate to deviate significantly from the 

regional climate. 

On a larger and longer-term scale, climate change is a subject of national and international 

interest. The GCRP (GCRP 2009) has provided valuable insights regarding the state of 

knowledge of climate change. The projected change in temperature from ‘present day’ 

(1993-2008) over the period encompassing the licensing action (i.e., to the period 2040 to 2059 

in the GCRP report) in the vicinity of the STP site is an increase of between 0 to 3°F. While the 

GCRP has not incrementally forecasted the change in precipitation by decade to align with the 

licensing action, the projected change in precipitation from the ‘recent past’ (1961-1979) to the 

period 2080 to 2099 was presented; the GCRP report forecasts a decrease of between 10 to 

15 percent (GCRP 2009). 

Based on the assessments of the GCRP and the National Academy of Sciences’ National 

Research Council, the EPA determined that potential changes in climate caused by greenhouse 

gas (GHG) emissions endanger public health and welfare (74 FR 66496). The EPA indicated 

that, while ambient concentrations of GHGs do not cause direct adverse health effects (such as 

respiratory or toxic effects), public health risks and impacts can result indirectly from changes in 

climate. As a result of the determination by the EPA and the recognition that mitigative actions 

are necessary to reduce impacts, the review team concludes that the effect of GHG on climate 

and the environment is already noticeable, but not yet destabilizing. In CLI-09-21, the 

Commission provided guidance to the NRC staff to consider carbon dioxide and other GHG 

emissions in its NEPA reviews and directed that it should encompass emissions from 

constructing and operating a facility as well as from the fuel cycle (NRC 2009b). NRC Staff 
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February 2011 2-163 NUREG-1937 

Memorandum (NRC 2010) provides additional guidance to NRC staff on consideration of GHGs 

and carbon dioxide in its environmental reviews. The review team characterized the affected 

environment and the potential GHG impacts of the proposed action and alternatives in this EIS. 

Consideration of GHG emissions was treated as an element of the existing air quality 

assessment that is essential in a NEPA analysis. In addition, where it was important to do so, 

the review team considered the effects of the changing environment during the period of the 

proposed action on other resource assessments. 

2.9.1.1 Wind 

Wind at the STP site is consistent with the dominant influence of the Azores high and the 

coastal location of the site. The seasonal variation of the prevailing directions shows a 

predominance of southeasterly winds except in January, July, and August when south winds 

prevail, and November and December when northerly winds prevail (STPNOC 2009a). The 

coastal location of the site is expected to lead to typical onshore (southeast) winds during the 

day and offshore winds at night. Also, because the diurnal fluctuation of land temperatures is 

greater than the fluctuation of water temperatures and the land-water temperature difference is 

greater during the day than it is at night, the review team expects that the daytime onshore wind 

speeds would be greater than the nighttime offshore speeds. Wind direction persistence is 

generally limited to 4 hr or less; persistence of 8 hr or longer occurs less than 10 percent of the 

time, and persistence of 12 hr or longer occurs less than 4 percent of the time. 

2.9.1.2 Temperature 

Neither the ER (STPNOC 2009a) nor the FSAR (STPNOC 2009b) provide onsite temperature 

information for the STP site. Consequently, the review team determined that the average 

temperatures at the site are consistent with the temperature data from Palacios, Victoria and 

Corpus Christi. Based on data in Table 2.7-4 of the ER (STPNOC 2010a) for observations at 

15 NWS and cooperative observing stations and the climatological record for the Corpus Christi 

NWS station, the temperature extremes at the site would be about 10°F and 108°F. These 

values are within the ranges of extremes observed (i.e., 4°F to 13°F and 102°F to 112°F for 

lows and highs, respectively). 

2.9.1.3 Atmospheric Moisture 

The STP meteorological system measures dewpoint temperature. However, neither the ER nor 

the FSAR presents onsite atmospheric moisture data. Consequently, the review team 

determined that the relative humidity data for Palacios and the Corpus Christi NWS station are 

representative of the STP site. Relative humidities for 0600 local standard time (LST) 

approximate the daily maximum values. Monthly average 0600 LST relative humidities range 

from about 86 percent in December to about 94 percent in August. Relative humidities for 

1200 LST approximate the daily minimum relative humidity. Monthly average 1200 LST relative 
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NUREG-1937 2-164 February 2011 

humidities range from a high of about 67 percent in January to low of about 56 percent in July. 

Climatological statistics for Corpus Christi and Victoria indicate that STP site could expect heavy 

fog 30 to 40 days per year. Palacios fog data included in the ER are consistent with this 

expectation. The likelihood of fog is greatest from November through March and least from 

June through August. 

2.9.1.4 Severe Weather 

The site can experience severe weather in the form of thunderstorms, tornadoes, and tropical 

storms. Thunderstorms are the most frequent severe weather events. They occur on an 

average of about 55 days per year at Victoria, and about 31 days per year at Corpus Christi. 

The majority of the thunderstorms occur from May through September. It is likely that the 

frequency of thunderstorms at the STP site is closer to that of Corpus Christi, because of the 

site’s proximity to the coastline, than to Victoria. Tropical cyclones, including hurricanes and 

tropical storms, pass near the STP site an average of about once every other year and an 

average of about two to three hurricanes pass near the site every 10 years. Nine hurricanes 

have made landfall between Corpus Christi and Galveston since 1950; the most recent being 

hurricanes Humberto in 2007 and Ike in 2008. Tornadoes are the least frequent of these 

extreme weather events. Using tornado statistics from 1950 through 2003 and the methodology 

outlined in NUREG/CR-4461, Tornado Climatography of the Contiguous United States

(Ramsdell and Rishel 2007), the NRC staff estimates that the probability of a tornado striking 

the nuclear island at the STP site is about 2×10-4 yr-1. 

2.9.1.5 Atmospheric Stability 

Atmospheric stability is a derived meteorological parameter that describes the dispersion 

characteristics of the atmosphere. It can be determined by the difference in temperature 

between two heights. A seven-category atmospheric stability classification scheme based on 

temperature differences is set forth in Regulatory Guide 1.23, Revision 1 (NRC 2007b). When 

the temperature decreases rapidly with height, the atmosphere is unstable and atmospheric 

dispersion is greater. Conversely, when temperature increases with height, the atmosphere is 

stable and dispersion is more limited. Typically, the atmospheric stability is classified as neutral 

to unstable during the day and neutral to stable at night. Cloudiness and high winds tend to 

decrease both stability and instability resulting in more nearly neutral conditions. 

Measurements at the 10- and 60-m levels of the STP meteorological tower are used to 

determine atmospheric stability for the STP site. On an annual basis, the atmosphere at the 

STP site is stable about 46 percent of the time, neutral about 29 percent of the time, and 

unstable about 25 percent of the time. These percentages vary seasonally with more frequent 

stable and unstable conditions in the summer and early fall, and more frequent neutral 

conditions in the winter and early spring (STPNOC 2009a). 
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February 2011 2-165 NUREG-1937 

Large water bodies, notably the Gulf of Mexico and the STP MCR, have the potential to affect 

atmospheric stability. The STP meteorological tower is sufficiently far from both the Gulf and 

the MCR that the review team concludes that it is unlikely that either has an effect on 

determining atmospheric stability for the environmental review. 

2.9.2 Air Quality 

The discussion on air quality includes the six common “criteria pollutants” for which the EPA has 

set national ambient air quality standards (ozone, particulate matter, carbon monoxide, nitrogen 

oxides, sulfur dioxide, and lead). The air quality discussion also covers heat-trapping 

“greenhouse gases” (primarily carbon dioxide) which have been the principal factor causing 

climate change over the last 50 years (GCRP 2009). 

The STP site is in central Matagorda County, Texas at the southern edge of the Metropolitan 

Houston-Galveston Intrastate Air Quality Control Region (40 CFR 81.38). The Corpus ChristiVictoria Intrastate Air Quality Control Region (40 CFR 81.136) lies immediately south and west 

of Matagorda County. All of the counties in these Air Quality Control Regions adjacent to the 

STP site are in compliance with the National Ambient Air Quality Standards (40 CFR 81.344) 

except Brazoria County to the north; Brazoria County is classified Non-Attainment/Severe 

relative to the 8-hr ozone standard and lead for which no designation has been made. There is 

no mandatory Class I Federal Area where visibility is an important value within 100 mi of the 

STP site. 

Carbon dioxide concentration has been building up in the Earth’s atmosphere since the 

beginning of the industrial era in the mid-1700s, primarily due to the burning of fossil fuels (coal, 

oil, and natural gas) and the clearing of forests. Human activities have also increased the 

emissions of other greenhouse gases such as methane, nitrous oxide, and halocarbons. These 

emissions are increasing the optical thickness of heat-trapping gases in the Earth’s atmosphere, 

causing global surface temperatures to rise (GCRP 2009). 

2.9.3 Atmospheric Dispersion 

As described in Section 2.9.4, the NRC staff visited the meteorological measurement system at 

the site and reviewed the available information on the design of the meteorological 

measurement program, and evaluated data collected by the program. Based on this 

information, the NRC staff concludes that the program provides data that represent the affected 

environment onsite meteorological conditions as required by 10 CFR 100.20. The data also 

provide an acceptable basis for making estimates of atmospheric dispersion for the evaluation 

of the consequences of routine and accidental releases required by 10 CFR 50.34, 10 CFR 

Part 50, Appendix I and 10 CFR 52.79. 
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NUREG-1937 2-166 February 2011 

2.9.3.1 Short-Term Dispersion Estimates

STPNOC calculated short-term dispersion estimates using 3 years of onsite meteorological data 

(STPNOC 1997, 1999, and 2000). These estimates which were provided in ER Section 2.7.5.2 

were based on distances to the Exclusion Area Boundary (EAB) and outer boundary of the Low 

Population Zone (LPZ) in ER Table 2.7-13 (STPNOC 2010a). The exclusion area and LPZ are 

defined in 10 CFR 50.2. STPNOC (2009c) revised these distances in response to an NRC 

request for additional information (NRC 2009a) and recalculated the dispersion estimates. 

Based on its review of the revised dispersion estimates, the NRC staff determined that the 

revised estimates did not appropriately reflect realistic dispersion conditions at the site. 

Consequently, using the revised EAB and LPZ distances, the NRC staff calculated site-specific 

short-term dispersion estimates for the EIS design basis accident review. 

The NRC staff’s short-term dispersion estimates for use in design basis accident calculations 

are listed in Table 2-39. They are based on the PAVAN computer code (Bander 1982) 

calculations of 1-hr and annual average atmospheric dispersion (χ/Q) values from a joint 

frequency distribution of wind speed, wind direction and atmospheric stability. These values 

were calculated for the shortest distances from a release boundary envelope that encloses the 

Unit 3 or Unit 4 release points to the EAB and to the LPZ. The EAB χ/Q value listed in Table 

2-40 is the median 1-hr χ/Q, which is assumed to persist for 2 hr. The LPZ χ/Q values listed in 

Table 2-40 were determined by logarithmic interpolation between the median 1-hr χ/Q, which 

was assumed to persist for 2 hr, and the annual average χ/Q following the procedure described 

in Regulatory Guide 1.145 (NRC 1983). 

Table 2-39. Atmospheric Dispersion Factors for Proposed Units 3 and 4 Design Basis Accident 

Calculations 

Time period Boundary χ/Q (s/m3

) 

0 to 2 hours Exclusion Area Boundary 3.64×10-5

0 to 8 hours(a) Low Population Zone 2.53×10-6

8 to 24 hours(a) Low Population Zone 2.23×10-6

1 to 4 days(a)

 Low Population Zone 1.70×10-6

4 to 30 days(a)

 Low Population Zone 1.15×10-6

(a) Times are relative to beginning of the release to the environment. 
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February 2011 2-167 NUREG-1937 

Table 2-40. Maximum Annual Average Atmospheric Dispersion and Deposition Factors for 

Evaluation of Normal Effluents for Receptors of Interest 

Receptor 

Downwind 

Sector 

Distance 

(mi) 

No Decay 

χ/Q (s/m3)

2.26-Day 

Decay 

χ/Q (s/m3

) 

8-Day 

Decay 

χ/Q (s/m3) 

D/Q 

(1/m2) 

EAB NW 0.52 1.5×10-5 1.5×10-5 1.4×10-5 1.0×10-7

Site Boundary NNW 0.69 8.1×10-6 8.1×10-6 7.3×10-6 6.4×10-8

Residence WSW 2.18 6.3×10-7

 6.2×10-7 5.1×10-7 1.8×10-9(a)

Meat Animal WSW 2.18 6.3×10-7

 6.2×10-7 5.1×10-7 1.8×10-9(a)

Veg. Garden WSW 2.18 6.3×10-7

 6.2×10-7 5.1×10-7 1.8×10-9(a)

Unit 4 Reactor WNW 0.17 8.3×10-5

 8.3×10-5 8.0×10-5 3.4×10-7

(a) 3.03 mi NNW 

2.9.3.2 Long-Term Dispersion Estimates 

Long-term dispersion estimates for use in evaluation of the radiological impacts of normal 

operations were calculated by STPNOC using the XOQDOQ computer code (Sagendorf et al. 

1982). This code implements the guidance set forth in Regulatory Guide 1.111 (NRC 1977) for 

estimation of χ/Q values and deposition factors (D/Q) for use in evaluation of the consequences 

of normal reactor operations. In July 2009, STPNOC (STPNOC 2009c, e) revised the distances 

used for calculating χ/Q and D/Q estimates for specific receptors of interest including the closest 

point of the EAB, the closest residence, the closest meat animal, and the closest vegetable 

garden. 

The results of the STPNOC calculations are presented in Table 2-40 for receptors of interest. 

Table 2-40 also includes χ/Q and D/Q estimates at the Unit 4 location for releases from Unit 3 

for use in estimating Unit 4 construction worker doses after Unit 3 begins operation. 

Table 2.7-16 in the ER (STPNOC 2010a) presents annual average atmospheric dispersion and 

deposition factors for 22 distances between 0.25 and 50 mi from the release point for each of 

16 direction sectors. 

2.9.4 Meteorological Monitoring 

There has been a meteorological monitoring program at the STP site since July 1973. The 

initial measurements were to provide the onsite meteorological information required for licensing 

of the existing STP Units 1 and 2. Measurements have continued in support of the existing STP 

Units 1 and 2 operations. The meteorological system was upgraded to enhance reliability in 

December 1994 and again in 2005 (STPNOC 2010a). The 1994 system provided the data used 

by STPNOC in preparation of the COL application. 

The 1994 and 2005 instrument systems are described in Section 6.4 of the STPNOC ER 

(STPCNOC 2010a). The primary meteorological tower is situated about 1.3 mi east of the 
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NUREG-1937 2-168 February 2011 

proposed location of proposed Units 3 and 4. The primary meteorological tower instruments 

include wind speed and direction and temperature sensors at 10 m and 60 m above ground, 

dew point temperature at 10 m above ground, and precipitation and solar radiation near ground 

level. A 10-m backup meteorological tower is located about 0.4 mi south of the primary tower. 

Instrumentation on the backup tower consists of wind speed and direction and temperature at 

10 m. Table 6.4-4 of the ER (STPNOC 2010a) lists the instrumentation in the 1994 

measurement system and compares instrument specifications with criteria set forth in NRC 

guidance and industry standards. 

The NRC staff viewed the meteorological site and instrumentation, reviewed the available 

information on the meteorological measurement program, and evaluated data collected by the 

program. Based on this information, the NRC staff concludes that the program provides data 

that represent the affected environment onsite meteorological conditions as required by 

10 CFR 100.20. The data also provide an acceptable basis for making estimates of 

atmospheric dispersion for the environmental review evaluation of the consequences of routine 

and accidental releases required by 10 CFR 50.34, 10 CFR Part 50, Appendix I and 

10 CFR 52.79. 

2.10 Nonradiological Health 

This section describes aspects of the environment at the STP site and within the vicinity of the 

site associated with nonradiological human health impacts. The section provides the basis for 

evaluation of impacts to human health from building and operation of the proposed Units 3 and 

4. Building activities have the potential to affect public and occupational health, create impacts 

from noise, and impact health of the public and workers from transportation of construction 

materials and personnel to the STP site. Operation of the proposed Units 3 and 4 has the 

potential to impact the public and workers at the STP site from operation of the cooling system, 

noise generated by operations, electromagnetic fields (EMF) generated by transmission 

systems, and transportation of operations and outage workers to and from the STP site. 

2.10.1 Public and Occupational Health 

This section describes public and occupational health at the STP site and vicinity associated 

with air quality, occupational injuries and etiological agents (i.e., disease causing 

microorganisms). 

2.10.1.1 Air Quality 

Public and occupational health can be impacted by changes in air quality from activities that 

contribute to fugitive dust, vehicle and equipment exhaust emissions, and automobile exhaust 

from commuter traffic (NRC 1996). Air quality for Matagorda County is discussed in 

Section 2.9.2. Fugitive dust and other particle material (including PM10 [particle matter less than 
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February 2011 2-169 NUREG-1937 

10 microns] and PM2.5) can be released into the atmosphere during any site excavations and 

while grading is being conducted. Most of these activities that generate fugitive dust are short in 

duration, over a small area, and can be controlled using watering, application of soil adhesives, 

seeding, and other best management practices (STPNOC 2010a). Mitigation measures to 

minimize and control fugitive dust are required for compliance with all Federal, State, and local 

regulations that govern such activities (NRC 1996; STPNOC 2010a). 

Exhaust emissions during normal plant operations associated with on-site vehicles and 

equipment as well as from commuter traffic can affect air quality and human health. 

Nonradiological supporting equipment (e.g., diesel generators, fire pump engines), and other 

nonradiological emission-generating sources (e.g., storage tanks) or activities are not expected 

to be a significant source of criteria pollutant emissions. Diesel generators and supporting 

equipment would be in place for emergency-use only but would be started regularly to test that 

the systems are operational. Emissions from nonradiological air pollution sources are permitted 

by TCEQ. The ER (STPNOC 2010a) states that the current permit for STP operations was 

renewed on January 25, 2006, and is valid until January 25, 2011. STPNOC also complies with 

TCEQ’s permit for operation of portable and emergency engines and turbines 

(30 TAC Section 106.511). The authorization states that the maximum annual operating hours 

for the emergency diesel generators for Units 1 and 2 as well as any future systems shall not 

exceed 10 percent of the normal annual operating schedule for the primary equipment. 

2.10.1.2 Occupational Injuries 

In general, occupational health risks to workers and onsite personnel engaged in activities such 

as building, maintenance, testing, excavation and modifications are expected to be dominated 

by occupational injuries (e.g., falls, electric shock, asphyxiation) or occupational illnesses. 

Historically, actual injury and fatality rates at nuclear reactor facilities have been lower than the 

average U.S. industrial rates. The U.S. Bureau of Labor Statistics provides reports that account 

for occupational injuries and illnesses as total recordable cases, which includes those cases 

that result in death, loss of consciousness, days away from work, restricted work activity or job 

transfer, or medical treatment beyond first aid. The State of Texas also tracks the annual 

incidence rates of injuries and illnesses for electric power generation, transmission and 

distribution workers. These records of statistics are used to estimate the likely number of 

occupational injuries and illnesses for operation of Units 1 and 2 and predict the likely number of 

cases for the proposed new units. 

Occupational injury and fatality risks are reduced by strict adherence to NRC and OSHA safety 

standards, practices, and procedures to minimize worker exposures. Appropriate State and local 

statutes also must be considered when assessing the occupational hazards and health risks 

associated with the STP site. Currently, STPNOC has programs and personnel to promote safe 

work practices and respond to occupational injuries and illnesses for Units 1 and 2. Procedures 

are in place with the objective to provide personnel who work at the STP site with an effective 
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NUREG-1937 2-170 February 2011 

means of preventing accidents due to unsafe conditions and unsafe acts. They include safe 

work practices to address hearing protection, confined space entry, personal protective 

equipment, heat stress, electrical safety, ladders, chemical handling, storage, and use, as well as 

other industrial hazards. Personnel are provided training on STPNOC safety procedures. In 

addition, STPNOC requires contractors to develop and implement safety procedures with the 

intent of preventing injuries, occupational illnesses, and deaths (STPNOC 2010a). 

2.10.1.3 Etiological Agents 

Public and occupational health can be compromised by activities at the STP site that encourage 

the growth of disease causing microorganisms (etiological agents). Thermal discharges from 

Units 1 and 2 into the MCR and then into the Colorado River have the potential to increase the 

growth of thermophilic microorganisms. As mentioned in Section 2.3.3.1, the segment of the 

Colorado River adjacent to the STP site is listed by TCEQ as impaired by the presence of 

bacteria. The types of organisms of concern for public and occupational health include enteric 

pathogens (such as Salmonella spp. and Pseudomonas aeruginosa), thermophilic fungi, 

bacteria (such as Legionella spp.), and free-living amoeba (such as Naegleria fowleri and 

Acanthamoeba spp.). These microorganisms could result in potentially serious human health 

concerns, particularly at high exposure levels. 

A review of the outbreaks of human water-borne diseases in Texas indicates that the incidence 

of most of these diseases is not common. Outbreaks of Legionellosis, Salmonellosis, or 

Shigellosis that occurred in Texas from 1996 to 2008 were within the range of national trends in 

terms of cases per 100,000 population or total cases per year, and the outbreaks were 

associated with pools, spas, or lakes (CDC 1997, 1998b, 1999, 2001, 2002b, 2003, 2004b, 

2005, 2006b, 2007, 2008d, 2009, 2010). Texas does have higher incidences of infection by 

Naegleria fowleri compared to most other States in the country. Infection with N. fowleri causes 

the disease primary amebic meningoencephalitis (PAM), a brain infection that leads to the 

destruction of brain tissue and is fatal (CDC 2008c). From 1995 to 2007, there were three 

waterborne disease outbreaks in Texas (one each in 1998, 1999, and 2002). None of the 

outbreaks were from recreational exposure to untreated water (e.g., swimming or boating in a 

river) (CDC 1998a, 2000, 2002a, 2004a, 2006a, 2008a, b). From 1972 to 2007, there have 

been 36 occurrences of PAM in Texas, ranging from zero to five cases per year. All of these 

cases were fatal, exposures occurred during the months of June through September, and four 

exposures occurred in lakes and one occurred in a river. In a review of documentation of PAM 

cases in Texas dating back to 1972, none of the cases of PAM appear to be from exposure to 

waters in Matagorda County (CDC 1998a, 2000, 2002a, 2004a, 2006a, 2008a, b; LCRA 2007c; 

TDSHS 1995, 1997). The review team contacted the CDC in October 2009 and confirmed that 

there have been a few cases of PAM in the State of Texas since 2007; however, these cases 

were not in Matagorda County (CDC 2009). 
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February 2011 2-171 NUREG-1937 

2.10.2 Noise 

Sources of noise at the STP site are those associated with operation of Units 1 and 2, including 

transformers and other electrical equipment, circulating water pumps, and the public address 

system. The STP site is located on 12,220 ac surrounded by farmland and the Colorado River. 

There are 10 residences within 5 mi of the STP site, with the closest residence about 1.5 mi 

west-southwest of the EAB (STPNOC 2010a). The rural surroundings and enclosure of noisegenerating equipment in facilities help to mitigate onsite noise perceived by offsite receptors. 

There are no measurements of noise at the STP site (STPNOC 2010a). 

Activities associated with building the new units at the STP site would have peak noise levels in 

the range of 100- to 110-decibels on the A-weighted scale (dBA). As illustrated in Table 2-41, 

noise strongly attenuates with distance. A decrease of 10-dBA in noise level is generally 

perceived as cutting the loudness in half. At a distance of 50 ft from the source these peak 

noise levels would generally decrease to the 80- to 95-dBA range and at distance of 400 ft, the 

peak noise levels would generally be in the 60- to 80-dBA range. For context, the sound 

intensity of a quiet office is 50 dBA, normal conversation is 60 dBA, busy traffic is 70 dBA, and a 

noisy office with machines or an average factory is 80 dBA (Tipler 1982). 

Table 2-41. Construction Noise Sources and Attenuation with Distance 

Source

Noise 

Level (dBa) 

(peak)

Noise Level (dBa) 

Distance from Source

50 ft 100 ft 200 ft 400 ft

Heavy trucks 95 84–89 78–83 72–77 66–71 

Dump trucks 108 88 82 76 70 

Concrete mixer 105 85 79 73 67 

Jackhammer 108 88 82 76 70 

Scraper 93 80–89 74–82 68–77 60–71 

Dozer 107 87–102 81–96 75–90 69–84 

Generator 96 76 70 64 58 

Crane 104 75–88 69–82 63–76 55–70 

Loader 104 73–86 67–80 61–74 55–68 

Grader 108 88–91 82–85 76–79 70–73 

Dragline 105 85 79 73 67 

Pile driver 105 95 89 83 77 

Forklift 100 95 89 83 77 

Source: Golden et. al 1980 
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NUREG-1937 2-172 February 2011 

Regulations governing noise associated with the activities at the STP site are generally limited 

to worker health. Federal regulations governing construction noise are found in 29 CFR 

Part 1910, Occupational Health and Safety Standards, and 40 CFR Part 204, Noise Emission 

Standards for Construction Equipment. The regulations in 29 CFR Part 1910 deal with noise 

exposure in the construction environment, and the regulations in 40 CFR Part 204 generally 

govern the noise levels of compressors. Although several Texas municipalities have noise 

ordinances, the State of Texas does not have noise regulations covering rural areas that would 

be applicable to the STP site. 

2.10.3 Transportation 

The highway and rail transportation network surrounding the STP site is shown in Figure 2-2. 

According to the ER (STPNOC 2010a), all roadways in the area are composed of a treated 

bituminous surface. The sole access road to the STP site for operations workers at Units 1 and 

2 is FM 521. FM 521 is fed from the east by US Highway 60, from the north by FM 1468, and 

from the west by US Highway 35 and FM 1095. Existing traffic for Units 1 and 2 will continue to 

enter the site via the east entrance to the plant. There are north and west entrances to the site 

that may be used in the future. There is a 9-mi railroad spur north of the site that could be used 

in the future to transport heavy components and oversized equipment to the STP site for 

building of the proposed new units. The rail line would be upgraded and the rail route to 

Buckeye would be reestablished (STPNOC 2010a). Some large equipment items could also be 

transported to the STP site by barge. Heavy components would be transported by barge to the 

existing STP barge slip on the Lower Colorado River (Figure 2-3). The components would be 

offloaded from the barge and transported to the construction site by truck. A 2.5-mi heavy haul 

route, entirely within the site, would be built from the barge slip to the construction site. 

2.10.4 Electromagnetic Fields 

Transmission lines generate both electric and magnetic fields, referred to collectively as EMF. 

Public and worker health can be compromised by acute and chronic exposure to EMF from 

power transmission systems, including switching stations (or substations) on-site and 

transmission lines connecting the plant to the regional electrical distribution grid. Transmission 

lines operate at a frequency of 60 Hz (60 cycles per second), which is considered to be 

extremely low frequency (ELF). In comparison, television transmitters have frequencies of 55 to 

890 MHz and microwaves have frequencies of 1000 MHz and greater (NRC 1996). 

Electric shock resulting from direct access to energized conductors or from induced charges in 

metallic structures is an example of an acute effect from EMF associated with transmission lines 

(NRC 1996). Objects near transmission lines can become electrically charged by close 

proximity to the electric field of the line. An induced current can be generated in such cases, 

where the current can flow from the line through the object into the ground. Capacitive charges 

can occur in objects that are in the electric field of a line, storing the electric charge, but isolated 
Affected Environment 

February 2011 2-173 NUREG-1937 

from the ground. A person standing on the ground can receive an electric shock from coming 

into contact with such an object because of the sudden discharge of the capacitive charge 

through the person’s body to the ground. Such acute effects are controlled and minimized by 

conformance with National Electrical Safety Code (NESC) criteria and adherence to the 

standards for transmission systems regulated by the Public Utility Commission of Texas 

(PUCT). 

Long-term or chronic exposure to power transmission lines have been studied for a number of 

years. These health effects were evaluated in NUREG-1437, Generic Environmental Impact 

Statement for License Renewal of Nuclear Plants (GEIS) (NRC 1996, 1999)(a) for nuclear power 

in the United States, and are discussed in the ER (STPNOC 2010a). The GEIS (NRC 1996) 

reviewed human health and EMF and concluded: 

The chronic effects of electromagnetic fields (EMFs) associated with nuclear 

plants and associated transmission lines are uncertain. Studies of 60-Hz EMFs 

have not uncovered consistent evidence linking harmful effects with field 

exposures. EMFs are unlike other agents that have a toxic effect (e.g., toxic 

chemicals and ionizing radiation) in that dramatic acute effects cannot be forced 

and longer-term effects, if real, are subtle. Because the state of the science is 

currently inadequate, no generic conclusion on human health impacts is possible. 

2.11 Radiological Environment 

A radiological environmental monitoring program (REMP) has been conducted around the STP 

site since operations began in 1988. This program measures radiation and radioactive 

materials from all sources including the existing units at STP. The REMP includes the following 

exposure pathways: direct radiation, atmospheric, aquatic and terrestrial environments and 

groundwater and surface water. A pre-operational environmental monitoring program was 

conducted beginning in 1986 to establish a baseline to observe fluctuations of radioactivity in 

the environment after operations began. After routine operation of Unit 1 started in 1988 and 

Unit 2 started in 1989, the monitoring program continued to assess the radiological impacts on 

workers, the public and the environment. The results of this monitoring for the STP site are 

documented in annual reports entitled “Annual Radiological Environmental Operating Report” 

and “Annual Radioactive Effluent Release Report” (e.g., STPNOC 2010f, g). These reports 

show that exposures or concentrations in air, water, and vegetation are comparable to, if not 

statistically indiscernible from, pre-operational levels, with minor exceptions. The NRC’s Liquid 

Radioactive Release Lessons Learned Task Force Report (NRC 2006) made recommendations 

regarding potential unmonitored groundwater contamination at U.S. nuclear plants. In response 

 

(a) NUREG-1437 was originally issued in 1996. Addendum 1 to NUREG-1437 was issued in 1999. 

Hereafter, all references to NUREG-1437 include NUREG-1437 and its Addendum 1. 
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NUREG-1937 2-174 February 2011 

to that report, STPNOC summarized results of groundwater sampling performed by STPNOC 

around the STP site in its Annual Environmental Operating Report for 2007 (STPNOC 2008h).

As discussed in Section 2.3, drinking water in the area is obtained from deep aquifer wells, 

which are monitored quarterly. No tritium has been detected from monitoring of these wells.

Tritium is released to the MCR. Monitoring shows that levels of tritium in the shallow aquifer 

around the MCR originating from the liquids discharged to the MCR are below the EPA drinking 

water standard (40 CFR Part 141) (see Section 5.9.6). 

2.12 Related Federal Projects and Consultation 

The review team reviewed the possibility that activities of other Federal agencies might impact 

the issuance of COLs to STPNOC. Any such activities could result in cumulative environmental 

impacts and the possible need for another Federal agency to become a cooperating agency for 

preparation of the EIS. As discussed in Chapter 1, the Corps is a cooperating agency for 

preparation of this EIS. 

Federal lands within a 50-mi radius of the STP site include the Big Boggy and San Bernard 

National Wildlife Refuges administered by the FWS. The 5000-ac Big Boggy National Wildlife 

Refuge borders Matagorda Bay and is approximately 9 mi southeast of the STP site (STPNOC 

2010a). The 45,311-ac San Bernard National Wildlife Refuge contains coastal prairies and salt 

marshes in southern Matagorda and Brazoria counties. There are no wilderness areas or rivers 

included in the national wild and scenic rivers system within the 50-mi region. The closest 

Native American Tribal reservations are more than 50 mi from the STP site (STPNOC 2008f). 

The NRC is required under Section 102(2)(C) of NEPA to consult with and obtain the comments 

of any Federal agency that has jurisdiction by law or special expertise with respect to any 

environmental impact involved in the subject matter of the EIS. During the course of preparing 

this EIS, the NRC consulted with the FWS and NOAA Fisheries. A list of key consultation 

correspondence is identified in Appendix F. 

2.13 References 

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10 CFR Part 100. Code of Federal Regulations, Title 10, Energy, Part 100, “Reactor Site 

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29 CFR Part 1910. Code of Federal Regulations, Title 29, Labor, Part 1910, “Occupational 

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Diary.4, Robbins Floor Plan, 1992.33.192R0.7, 1992.33.192R0.8, 1992.33.192R0.9, Tadmore 

House Showing Fence & Windows, Tadmore House Showing Fate & Door, Tadmore House 

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Ross, S.T. 2001. The Inland Fishes of Mississippi. University Press of Mississippi, Jackson, 

Mississippi. 

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Ryder, P.D. and A.F. Ardis. 2002. Hydrology of the Texas Gulf Coast Aquifer Systems. 

Regional Aquifer-Systems Analysis-Gulf Coast Plain. U.S. Geological Survey Professional 

Paper 1416-E. U.S. Geological Survey, Reston, Virginia. 
Affected Environment 

NUREG-1937 2-186 February 2011 

Sagendorf, J.F., J.T. Goll, and W.F. Sandusky. 1982. XOQDOQ: Computer Program for the 

Meteorological Evaluation of Routine Effluent Releases at Nuclear Power Stations. 

NUREG/CR-2919, U.S. Nuclear Regulatory Commission, Washington, D.C. 

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Simons, T.R., F.R. Moore, and S.A. Gauthreaux. 2004. “Mist Netting Trans-Gulf Migrants at 

Coastal Stopover Sites: The Influence of Spatial and Temporal Variablility on Capture Data.” 

Studies in Avian Biology 29:135-143. 

South Texas Project Nuclear Generating Station. (STPNOC). 2007. 2006 Annual 

Environmental Operating Report for South Texas Project Nuclear Generating Station. South 

Texas Project Units 1 & 2. Accession No. ML071270211. 

South Texas Project Nuclear Operating Company (STPNOC). 2008a. Letter from Greg 

Gibson, STPNOC, to NRC, dated July 2, 2008, “Responses to Requests for Additional 

Information.” Accession No. ML081970465. 

South Texas Project Nuclear Operating Company (STPNOC). 2008b. Letter from Greg 

Gibson, STPNOC, to NRC, dated August 14, 2008, “Response to Requests for Additional 

Information.” Accession No. ML090270986. 

South Texas Project Nuclear Operating Company (STPNOC). 2008c. Letter from Scott Head, 

STPNOC, to NRC, dated December 18, 2008, ”Responses to Requests for Additional 

Information.” Accession No. ML090860873. 

South Texas Project Nuclear Operating Company (STPNOC). 2008d. Letter from Greg 

Gibson, STPNOC, to NRC, dated July 30, 2008, “Response to Requests for Additional 

Information.” Accession No. ML082140629. 

South Texas Project Nuclear Operating Company (STPNOC). 2008e. Letter from Greg 

Gibson, STPNOC, to NRC, dated July 15, 2008, ”Response to Requests for Additional 

Information.” Accession No. ML082040684. 

South Texas Project Nuclear Operating Company (STPNOC). 2008f. Letter from Greg Gibson, 

STPNOC, to NRC, dated February 28, 2008, “Responses to Environmental Report Site Audit 

Comments.” Accession No. ML080660150. 
Affected Environment 

February 2011 2-187 NUREG-1937 

South Texas Project Nuclear Operating Company (STPNOC). 2008g. Letter from Scott Head 

STPNOC, to NRC, dated December 30, 2008, "Response to Requests for Additional 

Information." Accession No. ML083660390. 

South Texas Project Nuclear Operating Company (STPNOC). 2008h. 2007 Annual 

Environmental Operating Report. STPEGS, Bay City, Texas. Accession No. ML081280093. 

South Texas Project Nuclear Operating Company (STPNOC). 2008i. Updated Final Safety 

Analysis Report Units 1 and 2, Revision 14. STPEGS, Bay City, Texas. 

South Texas Project Nuclear Operating Company (STPNOC). 2009a. Letter from Scott Head, 

STPNOC, to NRC, dated September 21, 2009, “Responses to Requests for Additional 

Information (RAI Letter Number 202).” Accession No. ML092710096. 

South Texas Project Nuclear Operating Company (STPNOC). 2009b. Letter from Scott Head 

STPNOC, to NRC, dated January 22, 2009, “Response to Request for Additional Information.” 

Accession No. ML090270720. 

South Texas Project Nuclear Operating Company (STPNOC). 2009c. Letter from Scott Head, 

STPNOC, to U.S. Army Corps, dated October 28, 2009, "South Texas Project, Permit 

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South Texas Project Nuclear Operating Company (STPNOC). 2010a. South Texas Project 

Units 3 and 4 Combined License Application, Part 3, Environmental Report. Revision 4, Bay 

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South Texas Project Nuclear Operating Company (STPNOC). 2010b. South Texas Project 

Units 3 and 4 Combined License Application, Part 2, Final Safety Analysis Report. Revision 4, 

Bay City, Texas. Accession No. ML102860517. 

South Texas Project Nuclear Operating Company (STPNOC). 2010c. Letter from Scott Head, 

STPNOC, to NRC, dated August 30, 2010, “Response to Request for Additional Information." 

Accession No. ML102450261. 

South Texas Project Nuclear Operating Company (STPNOC). 2010d. Letter from Mark 

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Draft Environmental Impact Statement." Accession No. ML102570059. 

South Texas Project Nuclear Operating Company (STPNOC). 2010e. Letter from Scott Head, 

STPNOC, to NRC, dated July 7, 2010, “Additional Information Regarding Draft Environmental 

Impact Statement." Accession No. ML101930157. 
Affected Environment 

NUREG-1937 2-188 February 2011 

South Texas Project Nuclear Operating Company (STPNOC). 2010f. 2009 Annual 

Environmental Operating Report, South Texas Project Electric Generating Station. Accession 

No. ML101260530. 

South Texas Project Nuclear Operating Company (STPNOC). 2010g. 2009 Radioactive 

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Texas Commission on Environmental Quality (TCEQ). 2005. TPDES Permit No. 

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Texas Commission on Environmental Quality (TCEQ). 2007. Letter from Mr. Kelly Holligan, 

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Phase II Rules; South Texas Project Electric Generating Station; TPDES Permit No. WQOOO 

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Texas Commission on Environmental Quality (TCEQ). 2008a. The 2008 Texas Water Quality 

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Texas Commission on Environmental Quality (TCEQ). 2008b. Search the Water Utility 

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Texas Commission on Environmental Quality (TCEQ). 2009a. Water Rights Database and 

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Texas Commission on Environmental Quality (TCEQ). 2009b. Colorado River Basin: 2004 

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Texas Commission on Environmental Quality (TCEQ). 2009c. 2008 Texas Water Quality 

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Affected Environment 

February 2011 2-189 NUREG-1937 

Texas Comptroller of Public Accounts (Texas Comptroller). 2008. Sales and Use Tax. 

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Meningoencephalitis.” Disease Prevention News, Vol. 55, No. 14. July 10, 1995. Austin, 

Texas. 

Texas Department of State Health Services (TDSHS). 1997. “Primary Amebic 

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21, 1997. Austin, Texas. 

Texas Department of Transportation (TxDOT). 2007. Gulf Intracoastal Waterway. 2005-2006 

Legislative Report to the 80th Texas Legislature, Austin, Texas. 

Texas Education Code, Title 2, Public Education. Chapter 41, “Equalized Wealth.” 

Texas Education Code, Title 2, Public Education. Chapter 42, “Foundation School Program.” 

Texas Historical Commission (THC). 2007. Response from William A. Martin for Lawrence 

Oaks,THC, to S.L. Dannhardt, STPNOC, dated January 19, 2007, Stamped Reply “No Historic 

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Texas Historical Commission (THC). 2010. Response from William A. Martin for Mark Wolfe, 

THC, to Ryan Whited, NRC, dated March 30, 2010, Stamped Reply: “No Historic Properties 

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Texas Natural Diversity Database. 2009. Wildlife Diversity Program of Texas Parks & Wildlife 

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Texas Parks and Wildlife Department (TPWD). 2002. The Texas Shrimp Fishery, Executive 

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Texas Parks and Wildlife Department (TPWD). 2003. Endangered and Threatened Animals of 

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Texas Parks and Wildlife Department (TPWD). 2007. Texas Gems - Clive Runnells Family 

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Affected Environment 

NUREG-1937 2-190 February 2011 

Texas Parks and Wildlife Department (TPWD). 2008a. Rare, Threatened, and Endangered 

Species of Texas l Species Search Results for Matagorda and Wharton County revised 7 Nov 

2008. Accessed April 12, 2009 at 

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Texas Parks and Wildlife Department (TPWD). 2008b. Mad Island Fact Sheet. Accessed at 

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Texas Parks and Wildlife Department (TPWD). 2008c. White-tailed Deer. Accessed 

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Texas Parks and Wildlife Department (TPWD). 2009a. Letter from Ross Melinchuk, Deputy 

Executive Director, TPWD, to Ray Whited, NRC, dated November 13, 2009, “Proposed 

alternative sites related to the combined license application for South Texas Project, Units 3 and 

4.” Accession No. ML093210221. 

Texas Parks and Wildlife Department (TPWD). 2009b. Central Texas Coast Wildlife Trail 

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Texas Parks and Wildlife Department (TPWD). 2009c. Endangered and Threatened Species, 

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Texas Parks and Wildlife Department (TPWD). 2009d. White-faced Ibis (Plegadis chihi). 

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Texas Parks and Wildlife Department (TPWD). 2009e. Reddish Egret (Egretta rufescens). 

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Texas Parks and Wildlife Department (TPWD). 2009f. Trans-Gulf Migrants. Accessed August 

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Texas Parks and Wildlife Department (TPWD). 2009g. Great Texas Coastal Birding Trail – Rio 

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Texas Parks and Wildlife Department (TPWD). 2009h. 15 Texas Freshwater Mussels Placed 

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Affected Environment 

February 2011 2-191 NUREG-1937 

Texas Parks and Wildlife Department (TPWD). 2009i. Rare, Threatened, and Endangered 

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Texas Parks and Wildlife Department (TPWD). 2009k. Saltwater Fishing. Austin, Texas. 

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Texas Parks and Wildlife Department (TPWD). 2009m. Wildlife Fact Sheets. Austin, Texas. 

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Texas Parks and Wildlife Department (TPWD). 2009n. Telephone call to Tonya Wiley, TPWD, 

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Texas Parks and Wildlife Department (TPWD). 2009o. 2009-2010 Texas Commercial Fish 

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Texas Parks and Wildlife Department (TPWD). 2009p. 2010-2011 Summary of Fishing and 

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Texas Railroad Commission (TRC). 2009b. Query for current producing oil and gas wells in 

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QueryAction.do. Accession No. ML100471604. 
Affected Environment 

NUREG-1937 2-192 February 2011 

Texas Railroad Commission (TRC). 2009c. Query for current producing oil and gas wells in 

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Texas State Historical Association (TSHA). 2009c. Handbook of Texas Online – Calhoun 

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Texas State Historical Association (TSHA). 2009d. Handbook of Texas Online – Jackson 

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Texas Water Code, Title 2, Water Administration. Chapter 11, “Water Rights.” 
Affected Environment 

February 2011 2-193 NUREG-1937 

Texas Water Code, Title 2, Water Administration. Chapter 36, “Groundwater Conservation 

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Texas Water Development Board (TWDB). 2006c. Summary of South Central Texas (L) 

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Texas Water Development Board (TWDB). 2007. State Water Plan - Water for Texas 2007. 

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U.S. Army Corps of Engineers (Corps). 2008. Final Environmental Impact Statement for the 

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Section, U.S. Army Corps of Engineers Galveston District to G. Gibson, South Texas Project 

Operating Company dated April 7, 2009, “Subject: SWG-2008-1351, South Texas Project 
Affected Environment 

NUREG-1937 2-194 February 2011 

Operating Company, Jurisdictional Determination, 7,000-Acre Mass Cooling Reservoir (MCR), 

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U.S. Army Corps of Engineers (Corps). 2009b. Preliminary Jurisdictional Determination From 

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U.S. Census Bureau (USCB). 2000b. QT-H1. General Housing Characteristics: 2000.Data Set: 

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U.S. Census Bureau (USCB). 2000c. DP-4. Profile of Selected Housing Characteristics: 2000. 

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U.S. Census Bureau (USCB). 2000e. QT-H1. General Housing Characteristics: 2000. Data 

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U.S. Census Bureau (USCB). 2000f. DP-4. Profile of Selected Housing Characteristics: 2000. 

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ML100471604. 
Affected Environment 

February 2011 2-195 NUREG-1937 

U.S. Census Bureau (USCB). 2000g. QT-H5. Physical Housing Characteristics - Vacant 

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U.S. Department of Labor Bureau of Labor Statistics (BLS). 2008. Local Area Unemployment 

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Affected Environment 

NUREG-1937 2-196 February 2011 

U.S. Environmental Protection Agency (EPA). 2009c. Sole Source Aquifers / Sole Source 

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U.S. Fish and Wildlife Service (FWS). 2009b. Texas Colonial Waterbird Census. Accessed 

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U.S. Fish and Wildlife Service (FWS). 2009c. Species Profile - Wood Stork (Mycteria 

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U.S. Fish and Wilflife Service (FWS). 2010. National Wetlands Inventory Data for Blessing, 

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Accession No. ML100471604. 

February 2011 3-1 NUREG-1937 

3.0 Site Layout and Plant Description 

The South Texas Project Electric Generating Station (STP) site is located in Matagorda County, 

Texas. STP Nuclear Operating Company (STPNOC) applied to the U.S. Nuclear Regulatory 

Commission (NRC) for combined construction permits and operating licenses (COLs) for 

proposed Units 3 and 4. In addition to the COL application, STPNOC has applied for the 

required permit from the U.S. Army Corps of Engineers (Corps) to conduct activities that result 

in alteration of waters of the United States (STPNOC 2010a). The proposed new units would be 

situated wholly within the existing STP site and adjacent to existing STP Units 1 and 2. The site 

is situated approximately 10 mi north of Matagorda Bay, 70 mi south-southwest of Houston, and 

12 mi south-southwest of Bay City, Texas, along the west bank of the Colorado River. 

This chapter describes the key plant characteristics that are used to assess the environmental 

impacts of the proposed actions. The information is drawn from STPNOC’s Environmental 

Report (ER) (STPNOC 2010b), its Final Safety Analysis Report (FSAR) (STPNOC 2010c), and 

supplemental documentation from STPNOC as referenced. 

Whereas Chapter 2 of this environmental impact statement (EIS) describes the existing 

environment of the proposed site and its vicinity, this chapter describes the physical layout of 

the proposed plant. This chapter also describes the physical activities involved in building and 

operating the plant and associated transmission lines. The environmental impacts of building 

and operating the plant are discussed in Chapters 4 and 5, respectively. This chapter is divided 

into four sections. Section 3.1 describes the external appearance and layout of the proposed 

plant. Section 3.2 describes the major plant structures and distinguishes structures that 

interface with the environment from those that do not interface with the environment or that 

interface with the environment temporarily. Section 3.3 describes the activities involved in 

building or installing each of the plant structures. Section 3.4 describes the operational activities 

of the plant systems that interface with the environment. References cited are listed in 

Section 3.5. 

3.1 External Appearance and Plant Layout 

The 12,220-ac STP site currently contains two pressurized water reactors and their associated 

facilities, which occupy approximately 300 ac. The existing Units 1 and 2 share a 7000-ac Main 

Cooling Reservoir (MCR) and a much smaller Essential Cooling Pond (ECP). Figure 2-1 in 

Chapter 2 provides the relative location of proposed Units 3 and 4, the MCR, and the Colorado 

River. Since the new reactors would look similar to the existing reactors, the photograph in 

Figure 3-1 taken at ground-level of the existing reactors is illustrative of the horizon in the 

direction of the proposed Units 3 and 4. 
Site Layout and Plant Description 

NUREG-1937 3-2 February 2011 

Figure 3-1. Representative Ground-Level Photograph of STP Units 1 and 2 (STPNOC 2010b) 

The proposed location for Units 3 and 4 is northwest of Units 1 and 2. The proposed new units 

would have a shared Exclusion Area Boundary (EAB) and a shared plant access road with the 

existing units. The vent stack for proposed Unit 3 would be the tallest new structure at 

approximately 249 ft above grade, which is of similar elevation to the highest point of the 

existing units. Units 3 and 4 would rely on the MCR as the main condenser heat sink just as 

Units 1 and 2 do currently. However, the proposed new units would not rely on the ECP as an 

Ultimate Heat Sink (UHS) in the event of an emergency; instead, Units 3 and 4 would rely on 

mechanical draft cooling towers as the UHS. 

3.2 Proposed Plant Structures, Systems, and Components 

This section describes each of the major plant structures: the reactor power system, structures 

that would have a significant interface with the environment during operation, and the balance of 

plant structures. All of these structures are relevant in the discussion of the impacts of building 

the proposed Units 3 and 4 in Chapter 4. Only the structures that interface with the environment 

are important to the operational impacts discussed in Chapter 5. 
 Site Layout and Plant Description 

February 2011 3-3 NUREG-1937 

3.2.1 Reactor Power Conversion System 

STPNOC has proposed building and operating two boiling water reactor (BWR) steam electric 

systems using the U.S. Advanced Boiling Water Reactor (ABWR) design, as modified by 

STPNOC’s proposed amendment to the ABWR design (STPNOC 2010d). The NRC certified 

the ABWR design in May 1997. The ABWR is a single-cycle, forced-circulation BWR, with a 

rated power of 3926 MW(t); General Electric (GE) Nuclear Energy sponsored the design 

certification application. The design incorporates features of the BWR designs in Europe, 

Japan, and the United States, and uses improved electronics, computer, turbine, and fuel 

technology. The U.S. ABWR design is similar to the international ABWR design, which was 

built at the Kashiwazaki Kariwa Nuclear Power Generation Station, Units 6 and 7, by the Tokyo 

Electric Power Company, Inc. 

The NRC staff’s formal review of the design certification application was initiated on 

March 31, 1989, when GE submitted its application for final design approval (FDA) and standard 

design certification for the U.S. ABWR design. The NRC staff issued the FDA, along with the 

“Final Safety Evaluation Report (FSER) Related to Certification of the Advanced Boiling Water 

Reactor Design” NUREG-1503 (NRC 1994) on July 13, 1994. On May 12, 1997, the NRC 

noticed the issuance of the U.S. ABWR final design certification rule in the Federal Register

(62 FR 25800). Applicants intending to build and operate a plant based on the U.S. ABWR 

design may do so by referencing the design certification rule, as set forth in Appendix A to 

Title 10, Part 52, of the Code of Federal Regulations (CFR). On August 11, 1997, the NRC 

issued a revised FDA based on the updated standard safety analysis report. 

This ABWR design is rated at 3926 MW(t), with a design gross electrical output of 

approximately 1356 MW(e) and a net output of 1300 MW(e). The reject heat from the unit to the 

environment, principally the atmosphere, is 2626 MW(t). Heat created in the reactor core is 

transferred to high-pressure and low-pressure turbines, which turns a generator creating 

electricity. Figure 3-2 provides an illustration of the reactor power conversion system. 

3.2.2 Structures, Systems, and Components with a Major Environmental 

Interface 

The review team divided the plant structures, systems, and components into two primary 

groups: those that interface with the environment and those that are internal to the reactor and 

associated facilities but without direct interaction with the environment. Examples of interfaces 

with the environment are withdrawal of water from the environment at the intake structures, 

release of water to the environment at the discharge structure, and release of excess heat to the 

atmosphere. The interaction of structures, systems, or components with environmental 

interfaces is considered in the review team’s assessment of the environmental impacts of facility 

construction and preconstruction, and facility operation in Chapters 4 and 5, respectively. The 

power-production processes that would occur within the plant itself and that do not affect the 
Site Layout and Plant Description 

NUREG-1937 3-4 February 2011 

environment are not relevant to a National Environmental Policy Act of 1969, as amended 

(NEPA) review and are not discussed further in this EIS. However, such internal processes are 

considered by the NRC staff in the ABWR design certification documentation and in the NRC 

safety review of the STPNOC COL application. This section describes the structures, systems, 

and components with a significant plant-environment interface. 

Figure 3-2. Simplified Flow Diagram of Reactor Power Conversion System (STPNOC 2010b) 

The remaining structures, systems, and components are discussed in Section 3.2.3, inasmuch 

as they may be relevant in the review team’s consideration of impacts discussed in Chapters 4 

and 5. Figure 3-3 illustrates the STP site layout with a grid overlay used to reference the 

locations of various plant structures and activity areas as they are described in the following 

sections. Existing STP Units 1 and 2 are located primarily in the E-6 to F-6 quadrants. 

Proposed Units 3 and 4 structures would be located primarily in the C-4, C-5, D-4, and 

D-5 quadrants. 
 Site Layout and Plant Description

February 2011 3-5 NUREG-1937 Figure 3-3. STP Site Layout Map
Site Layout and Plant Description 

NUREG-1937 3-6 February 2011 

3.2.2.1 Landscape and Stormwater Drainage 

Landscaping and the stormwater drainage system affect both the recharge to the subsurface 

and the rate and location that precipitation drains into adjacent creeks and streams. Impervious 

areas eliminate recharge to aquifers beneath the site. Pervious areas managed to reduce 

runoff and maintained free of vegetation would experience considerably higher recharge rates 

than adjacent areas with local vegetation. The stormwater management system, including site 

grading, drainage ditches, and swales, provides a safety function to keep locally intense 

precipitation from flooding safety-related structures. Figure 3-3 illustrates the site drainage for 

STP site in quadrants B-3 through D-3. The grading of the surface topography directs water 

away from safety structures and into ditches that drain away from the site into drainage ditches 

and creeks. 

3.2.2.2 Cooling Water System 

The circulating water cooling system and its principal components represents one of the largest 

interfaces between the proposed Units 3 and 4 and the environment. Cooling water would be 

withdrawn from the north shore of the MCR adjacent to the plant site through an intake structure 

located on the baffle dike; it would then circulate through the main condensers for proposed 

Units 3 and 4 after which it would return to the MCR through a shared discharge structure. 

Water lost from the MCR through ground seepage, evaporation, and release to the Colorado 

River is replaced with water withdrawn from the Colorado River at the Reservoir Makeup 

Pumping Facility (RMPF) located to the east of the proposed units. Water would be released 

from the MCR to the Colorado River to maintain water quality in the MCR. Water returned to 

the Colorado River enters the Colorado River through the discharge structure located on the 

west bank of the river approximately 2 mi downstream of the RMPF. The RMPF, the discharge 

structure on the Colorado River, and the MCR are components with a major plant-environment 

interface. All of these structures currently exist to support the operation of Units 1 and 2. 

While principally installed for the purpose of providing water to cool the proposed Units 3 and 4 

for 30 days following an accident, the two Unit 3 and 4 cooling towers are available as helper 

towers to provide for heat rejection to the atmosphere during normal operations. Blowdown 

from the cooling towers is returned to the MCR. All of these components are systems with a 

plant-environment interface. 

Reservoir Makeup Pumping Facility 

The RMPF is located along the west bank of the Colorado River. In the 1970s the RMPF was 

originally designed to support four units with an instantaneous rate of water diversion not to 

exceed 1200 cfs (NRC 1986). Two of the units were never constructed. Currently installed 

pumps have a maximum capacity of 600 cfs. STPNOC plans to limit pumping from the RMPF for 

all four units to the original design capacity of 1200 cfs (STPNOC 2010b). Therefore, there 
 Site Layout and Plant Description 

February 2011 3-7 NUREG-1937 

would be no increase in maximum makeup water pumping rate over the original design pumping 

rate. Currently, only half of the vertical traveling screens are operational and are used to support 

the operations of STP Units 1 and 2. To support four unit operation, new pumps and screens 

would be installed in the RMPF (STPNOC 2010b). Installation of pumps and screens would not 

result in any modifications to the intake structure or disturbances within the Colorado River. The 

Environmental Protection Agency’s (EPA’s) 316(b) Phase I regulations (66 FR 65256) that 

address cooling water intake structures state that “a facility that would otherwise be a ‘new 

facility’ would not be treated as a new facility under this rule if it withdraws water from an existing 

cooling water intake structure whose design capacity has not been increased to accommodate 

the intake of additional cooling water.” Therefore, the review team concludes that Units 3 and 4 

and the intake structure on the Colorado River that supports their operation would not qualify as 

a “new facility.” EPA is currently developing regulations that address cooling water systems for 

existing facilities, termed Phase II regulations, which would be applicable to STP Units 3 and 4. 

Until new regulations are developed, permit requirements related to cooling water intake 

structures at Phase II facilities are to be established on a case-by-case best professional 

judgment basis (72 FR 37107). 

The RMPF would withdraw water through a 406-ft-long intake structure located parallel to the 

shoreline. The RMPF consists of 24 traveling screens, each 10-ft wide, with the bottom of the 

screens located 10 ft below mean sea level (MSL) in the Colorado River (minimum water 

surface elevation in the Colorado River at the intake structure is at MSL) (STPNOC 2010e). 

Vertical trash racks with a 4-in. opening are located in front of the traveling screens. Short trash 

racks are also installed perpendicular to the river flow along the upstream and downstream 

margins of the intake structure. The traveling screens have a mesh size of 3/8 in. The surface 

area of the 24 traveling screens is 2400 ft2

 when the water surface elevation in the Colorado 

River is at MSL. Water from the river flows through the trash racks, then through traveling 

screens, and then over a weir into a small embayment before entering the intake pumps. The 

intake pumps pump the cooling water through pipelines into the MCR (STPNOC 2010b). New 

pumps to pump water to the MCR in support of proposed Units 3 and 4 would be installed. 

The RMPF vertical traveling screens are operated intermittently coincident with water 

withdrawals from the river. Rotation of the intake screens varies with debris loading. The design 

maximum approach velocity of the RMPF screens is approximately 0.5 ft/sec (STPNOC 2008). 

Organisms that swim through the trash racks can move laterally along the face of the intake 

structure and exit through the trash racks oriented perpendicular to the river flow located along 

the upstream or downstream margins of the structure. Fish and other organisms as well as 

debris impinged on the intake screens would be washed from the traveling screens and 

deposited in a sluice and discharge line and returned to the Colorado River. The point of return 

is at the downstream end of the intake structure, approximately 2 ft below normal water surface 

elevation (STPNOC 2008). 
Site Layout and Plant Description 

NUREG-1937 3-8 February 2011 

Discharge Structure 

Discharge from the MCR enters the Colorado River along the west bank through a series of 

seven 36-in. pipes directed downstream at an angle of 45-degrees from the shore. The 

discharge structures are located about 2 mi downstream of the RMPF. The pipes entering the 

river are spaced 250 ft apart. No change to the existing discharge structure is proposed. 

Main Cooling Reservoir 

The MCR is a 7000-ac engineered impoundment enclosed by an engineered embankment. The 

applicant reported that, at the maximum normal operating pool of 49 ft above MSL, the reservoir 

contains approximately 202,700 ac-ft of water. Dikes within the MCR increase the travel time of 

cooling water from the circulating water system discharge structure to the circulating water 

intake structure. The rejected heat from the existing and proposed units would enter the MCR 

in the form of sensible heat in the circulating water system. As the heated water circulates in 

the MCR, the heat is gradually dissipated to the environment through evaporation, conduction, 

and long-wave radiative cooling. The additional circulation water intake and discharge 

structures that would be required to connect the proposed Units 3 and 4 to the MCR are 

mentioned below. 

Ultimate Heat Sink Cooling Towers 

The UHS for Units 3 and 4 would consist of two water storage basins that would hold a sufficient 

amount of water to cool the units for 30 days of operation following an accident, without the 

need for makeup water and without exceeding design basis temperature and chemistry limits. 

The UHS would have mechanical draft cooling towers contiguous with the basins that would 

receive makeup water from groundwater wells, with backup from the MCR. The UHS cooling 

tower blowdown would discharge to the MCR. As stated above, the cooling towers could be 

operated to provide supplemental cooling of water in the circulating water system. 

Circulating Water Intake Structure 

A 131-ft by 392-ft concrete structure located within the MCR footprint would house eight pumps 

for the two proposed units. The structure would include traveling screens and trash racks. This 

structure is located in quadrants E-7 and E-8 of Figure 3-3. Pipes carrying water to the plant 

would run to the turbine building. 

Circulating Water Discharge Structure 

The water return from Units 3 and 4 turbine buildings would enter the MCR through a new 

discharge structure. The discharge structure would include a weir and a stilling basin to 

dissipate the velocity of the returning water before it enters the MCR. This structure is located 

in quadrant C-7 of Figure 3-3. 
 Site Layout and Plant Description 

February 2011 3-9 NUREG-1937 

Water Supply Wells 

STPNOC plans to use groundwater as the source for makeup water for proposed Units 3 and 4 

UHS, service water for the power plants, and water for sanitary and potable water systems 

(STPNOC 2010b). 

3.2.2.3 Other Permanent Plant-Environment Interfacing Structures, Systems, or 

Components 

Diesel Generators 

Diesel generators would be installed on the site to provide a backup source of power when the 

normal power source is disrupted. Three generators per unit would be installed in the proposed 

reactor buildings. Combustion emissions would be released to the atmosphere from the 

generators only during emergency operations and periodic testing. The reactor buildings 

housing the diesel generators are located in quadrants C-4 and D-4 of Figure 3-3. 

Combustion Turbine Generators 

One combustion turbine generator would be installed in each of the proposed unit’s turbine 

buildings. The operation of the generators results in combustion emissions to the atmosphere. 

Combustion turbine generators are used during off-normal conditions and are non-safety 

related. The turbine buildings containing the combustion turbine generators are located in 

quadrants C-4 and D-4 of Figure 3-3. 

Roads 

The workforce and a portion of plant materials would enter and exit the site via roads. Solid 

waste and radwaste are expected to be transported to the site via roadways. 

Slurry Wall 

To reduce the amount of water entering deep excavation for each unit’s reactor buildings, 

STPNOC proposed the combined use of a slurry wall and dewatering wells. A slurry wall 

reduces the permeability of the soil surrounding the excavation and thereby reduces the water 

entering the excavation. While the slurry wall is erected for the purpose of building the plant, it 

would remain in place and continue to reduce the permeability of the affected areas during 

operations. 

Fill Borrow Pit 

STPNOC indicated that fill material would be from qualified onsite borrow pits or qualified offsite 

borrow pits or both. The use of borrow pits would conform to local zoning requirements. 
Site Layout and Plant Description 

NUREG-1937 3-10 February 2011 

Railroad Lines 

A portion of the plant materials needed for plant construction and operation would enter and exit 

the site via a railroad line on the site. An existing 9-mi spur that ran from the STP site to 

Buckeye, Texas, is no longer in service. The service would be reestablished and the railroad 

line upgraded by installing new ballast or rail sections within the existing rail bed. The rail line is 

located in quadrants D-1 to E-3 to B-3 of Figure 3-3. 

Barge Facility and Colorado River Navigation Channel 

Dredging of the barge slip would be required to allow particularly heavy components and heavy 

equipment to be delivered to the site. Although there are no current plans to dredge the 

Colorado River Navigation Channel, it is possible dredging might be needed in the future. 

Main Drainage Channel 

The Main Drainage Channel (MDC) is an open ditch that eventually drains into Little Robbins 

Slough. A portion of the existing MDC has been relocated (STPNOC 2010e). 

Radwaste Facility 

Liquid, gaseous, and solid radioactive waste-management systems (SWMS) collect the 

radioactive materials that would be produced as byproducts of operating the proposed Units 3 

and 4. These systems process radioactive liquid, gaseous, and solid effluents to maintain 

releases within regulatory limits, as described in Section 3.4.3. 

Sanitary Waste Treatment Plant 

STPNOC proposes to replace the existing sanitary waste plant for Units 1 and 2 with a new 

facility to support the combined sanitary needs of all four units. The proposed sanitary waste 

treatment plant is located in quadrant C-6 of Figure 3-3. 

Power Transmission Structures 

As discussed in Section 2.2.2, STPNOC does not own or operate the existing transmission lines 

that serve the STP site. STPNOC has determined that no additional offsite transmission line 

corridors or expansion of existing corridors would be required to support Units 3 and 4 

(STPNOC 2010b). 

New onsite power transmission system components that would be needed to connect proposed 

Units 3 and 4 to the grid are (STPNOC 2010b): 

• a new 345-kV switchyard to serve Units 3 and 4 
 Site Layout and Plant Description 

February 2011 3-11 NUREG-1937 

• a new 345-kV tie-line from Units 1 and 2 to the new 345-kV switchyard 

• five existing transmission lines redirected into the Units 3 and 4 345-kV switchyard. 

The transmission system activities for Units 3 and 4 primarily would involve installation activities 

on the STP site. In addition, two existing transmission lines running approximately 20 mi from 

the STP site to the Hillje Substation located northwest of the STP site would be upgraded 

(STPNOC 2010b). The upgrade would involve reconductoring the two lines to accommodate 

the additional load of Units 3 and 4. In addition, some of the transmission line towers would be 

replaced to support the replacement conductors (STPNOC 2010b). The two transmission lines 

that would be upgraded are owned by CenterPoint Energy and American Electric Power Texas 

Central Company (STPNOC 2010b). Towers to support 345-kV transmission lines are made of 

steel and are built to meet the National Electrical Safety Code (STPNOC 2010b). 

3.2.2.4 Other Temporary Plant-Environment Interfacing Structures 

Some temporary plant-environment interfacing structures would need to be removed before 

proposed Units 3 and 4 operation commences; for example, a concrete batch plant. The 

impacts from the operation and installation of these structures are discussed in Chapter 4. 

Dewatering Wells 

Dewatering wells are used to lower the water table in areas that would otherwise be flooded by 

the influx of groundwater. Dewatering wells are planned to dewater deep excavations in the 

power block region. 

Cranes and Crane Footings 

Crane footings would be fabricated, and cranes would be erected on the site to build the plant. 

Concrete Batch Plant 

A concrete batch plant would be located in quadrants H-4 and I-4 of Figure 3-3. This area 

would house the equipment and facilities needed for delivery, materials handling and storage, 

and preparation of concrete. 

3.2.3 Structures with a Minor Environmental Interface 

The structures described in the following sections would have minimal plant-environment 

interface during plant operation. The impacts of these structures to the environment were 

determined by the review team to be of such minor significance that the structures are not 

discussed in Chapter 5. 
Site Layout and Plant Description 

NUREG-1937 3-12 February 2011 

Power Block 

The power block refers to the reactor building, the control building, the turbine building, the 

radwaste building, service buildings, and associated structures. The footprints of the reactor 

building, the control building, the turbine building, the radwaste building, and the service building 

are 198 ft by 188 ft, 185 ft by 89 ft, 317 ft by 350 ft, 128 ft by 218 ft, and 168 ft by 156 ft, 

respectively. These structures are located in quadrants C-4 and D-4 of Figure 3-3. The turbine 

building is the tallest building, reaching 140 ft above grade. The power block contains many 

safety-related structures, systems, and components. 

Pipelines 

The review team assumed that pipelines would follow existing roads or roads created while 

building the new units. Therefore, the installation of pipelines would be limited to areas already 

disturbed. Major pipelines include pipes running to and from each unit’s turbine buildings and 

the MCR. 

UHS Water Storage Basins 

The UHS water storage basins are engineered concrete structures 292 ft by 144 ft rectangular 

basins and 89.5 ft tall that would be built partially below grade. These basins provide water for 

cooling during off normal conditions and are safety related. 

Miscellaneous Buildings 

A variety of small buildings would exist throughout the site to support worker, fabrication, 

building, and operational needs (e.g., shop buildings, support offices, warehouses, guard 

houses). Some buildings may be temporary and would be removed after the plant begins 

operation. 

Parking 

A new parking area would also be graded and paved. This parking area is located in quadrant 

B-6 and C-6 of Figure 3-3. 

Laydown Areas 

Multiple laydown areas would be established to support fabrication and erection activities while 

building the plant and may be maintained as laydown areas for future maintenance and 

refurbishment of the plant. Laydown areas are graded relatively level and covered with crushed 

stone or gravel. Normally only limited vegetation is allowed in laydown areas. The locations of 

two new laydown areas are shown in quadrants A-3 to A-5 and B-4 to B-5 of Figure 3-3. 
 Site Layout and Plant Description 

February 2011 3-13 NUREG-1937 

Switchyard 

The location of the proposed switchyard is shown in quadrants C-3 and D-3 of Figure 3-3. The 

switchyard would remain free of vegetation. 

3.3 Construction and Preconstruction Activities 

The NRC’s authority is limited to construction activities that have a “reasonable nexus to 

radiological health and safety or common defense and security” (72 FR 57416) and the NRC 

has defined “construction” within the context of its regulatory authority. Examples of 

construction (defined at 10 CFR 50.10(a)) activities for safety-related structures, systems, or 

components include driving of piles; subsurface preparation; placement of backfill, concrete, or 

permanent retaining walls within an excavation; installation of foundations; or in-place assembly, 

erection, fabrication or testing. 

Other activities related to building the plant that do not require NRC approval (but may require a 

permit from the Corps) may occur before, during, or after NRC-authorized construction 

activities. These activities are termed “preconstruction” in 10 CFR 51.45(c) and may be 

regulated by other local, State, Tribal, or Federal agencies. Preconstruction includes activities 

such as site preparation (e.g., clearing, grading, erosion control and other environmental 

mitigation measures); erection of fences; excavation; erection of support buildings or facilities; 

building service facilities (e.g., roads, parking lots, railroad lines, transmission lines, sanitary 

treatment system, potable water system), dredging; and procurement or fabrication of 

components occurring at other than the final, in-place location at the site. Further information 

about the delineation of construction and preconstruction activities is presented in Chapter 4. 

This section describes the structures and activities associated with building proposed Units 

3 and 4. This section also characterizes the major activities for the principal structures to 

provide the requisite background for the assessment of environmental impacts. However, it 

does not represent a discussion of every potential activity or a detailed engineering plan. 

Table 3-1 provides general definitions and examples of activities that would be performed in 

building the new units. 

3.3.1 Major Activity Areas 

STPNOC (2010b) has stated that activities required to build the new units would occur primarily 

within the boundaries of the 12,220-ac site and in areas that have been previously disturbed. 

Dredging the navigation channel and obtaining offsite fill material, if needed, are examples of 

activities that would be conducted offsite. 
Site Layout and Plant Description 

NUREG-1937 3-14 February 2011 

Table 3-1. Descriptions and Examples of Activities Associated with Building Units 3 and 4 

Activity Description Examples 

Clearing Removing vegetation or existing structures from 

the land surface. 

Cutting forest in an area to be used for 

construction laydown. 

Grubbing Removing roots and stumps by digging. Removing stumps and roots from area that 

was cleared for construction laydown. 

Grading Reforming the elevation of the land surface to 

facilitate operation of the plant and drainage of 

precipitation. 

Minor leveling of the site from its current 

relatively level terrain. 

Hauling Transporting material and workforce along 

established roadways. 

Driving on new access road by construction 

workforce. 

Paving Laying impervious surfaces, such as asphalt 

and concrete, to provide roadways, walkways, 

parking areas, and site drainage. 

Paving parking area. 

Well drilling Drilling and completion of wells. Drilling wells for dewatering or water supply.

Excavation 

dewatering 

Pumping water from wells or pumping water 

directly to keep excavations from flooding with 

groundwater or surface runoff. 

Pumping water from excavation of base for 

reactor building. 

Grouting Installing low-permeability material in the 

subsurface around deep excavation to minimize 

movement of groundwater. 

Installing slurry wall around excavation for 

the reactor building. 

Deep excavation Digging an open hole in the ground. Deep 

excavation requires equipment with greater 

vertical reach than a backhoe. Deep excavation 

generally requires dewatering systems to keep 

the hole from flooding. 

Excavating to support fabrication of 

basemat for the reactor. 

Shallow excavation Digging a hole or trench to a depth reachable 

with a backhoe. Shallow excavation may not 

require dewatering. 

Placing pipelines; setting foundations for 

small buildings. 

Erection Assembling all modules into their final positions 

including all connection between modules. 

Using a crane to assemble reactor modules.

Fabrication Creating an engineered material from the 

assembly of a variety of standardized parts. 

Fabrication can include conforming native soils 

to some engineered specification (e.g., 

compacting soil to meet some engineered fill 

specification). 

Preparing and pouring concrete; laying 

rebar for basemat. 

Dredging Removing substrates and sediment in navigable 

waters including wetlands. 

Enlarging the barge slip. 

Dredge placement Placing fill material in areas not designated as 

wetlands. These materials can come from 

dredging wetlands. 

Placing sediments removed from the barge 

slip and navigation channel in a Corpsapproved placement area. 

Vegetation 

management 

Thinning, planting, trimming, and clearing 

vegetation. 

Maintaining switchyard free of vegetation 

during building. 

Filling of aquatic 

resources 

Discharging dredge and/or fill material into 

waters of the United States including wetlands. 

Placing a culvert for a roadway. 
 Site Layout and Plant Description 

February 2011 3-15 NUREG-1937 

Landscape and Stormwater Drainage 

The existing site grade would be raised to 34 ft MSL in the vicinity of safety-related structures 

such as the reactor building and UHS block. The STP Site Drainage and Layout Map, shown in 

Figure 2-12 of Chapter 2, also shows the site grade for proposed Units 3 and 4. Stormwater 

would drain based on the local ground slope. 

Reservoir Makeup Pumping Facility 

Refurbishment activities of the RMPF would include new pumps and screens within the existing 

structure’s footprint. 

Roads 

New onsite roads would be graded and paved. 

Slurry Wall 

The slurry wall would be installed into the Shallow Aquifer in the power block area. 

Railroads 

The existing railroad bed would be restored. 

Barge Facility 

Dredging would be required before barge shipments are offloaded at the barge slip under 

normal flow conditions. Dredge spoils would be hauled to a spoils disposal site approved by the 

Corps. 

Main Drainage Channel 

The MDC from the site has been relocated via shallow excavation of the new course. 

Power Transmission System 

Building the transmission system would involve the erection and fabrication of a switchyard and 

transmission lines. 

Sanitary Waste Treatment Plant 

Building the sanitary plant would involve limited fabrication and erection. 

Dewatering Wells 

Wells would be drilled using standard drilling practices into the Shallow Aquifer. 
Site Layout and Plant Description 

NUREG-1937 3-16 February 2011 

Cranes and Crane Footings 

Fabricating footings, building retaining walls, and erecting cranes would be needed to build the 

larger plant structures. 

Concrete Batch Plant 

Erecting the temporary concrete batch plant would occur on a cleared, graded area. 

Power Block 

The power block is composed of the reactor building, the radwaste building, the turbine building, 

service buildings, and associated structures. Deep excavation and extensive fill placement and 

large-scale fabrication and erection activities are involved. These deep excavations are 

expected to require installation of dewatering wells. An onsite concrete batch plant would 

fabricate concrete for numerous pours. Various components would be hauled to the site via rail, 

barge, and road. Many of these structures would be erected using components having been 

delivered as large modules and installed via crane. 

Circulating Water Intake 

Cofferdams would be required around the area within the MCR where the intake would be 

fabricated and erected to allow continued use of the MCR by Units 1 and 2. Once the 

installation is complete, the cofferdams would be removed and the site inundated again. 

Circulating Water Discharge 

Cofferdams would be required around the area within the MCR where the discharge would be 

fabricated and erected to allow continued use of the MCR by Units 1 and 2. Once the 

installation is complete, the cofferdams would be removed and the site inundated again. 

Pipelines 

The largest pipelines would be those connecting the circulating water from the turbine building 

and the MCR. These would require shallow excavation. 

UHS Water Storage Basins 

Deep excavation would be required to construct the reinforced concrete walls and floor of the 

safety-related UHS water storage basins. Structural fill would be placed around these basins. 

Miscellaneous Buildings 

Excavating for shallow foundations would be required before fabrication and erection of 

miscellaneous buildings. 
 Site Layout and Plant Description 

February 2011 3-17 NUREG-1937 

Parking 

Parking areas would be graded and paved. 

Laydown Areas 

Laydown areas would be graded and covered with gravel. 

Supply Wells 

Wells would be drilled using standard practices to the design depth. 

Switchyard 

Clearing and grading would be required for the proposed switchyard, and the fabrication and 

erection of electrical switching structures would need to occur. 

3.3.2 Summary of Resource Commitments During Construction and 

Preconstruction 

Table 3-2 provides a list of the significant resource commitments of construction and 

preconstruction. The values in this table combined with the affected environment described in 

Chapter 2 provide the basis for the impacts assessed in Chapter 4. These values were stated 

in the ER (STPNOC 2010b), and the review team determined that the values are not 

unreasonable. 

3.4 Operational Activities 

The operational activities considered in the review team’s environmental review are those 

associated with structures that interface with the environment, as described in Section 3.2.2. 

Examples of operational activities are withdrawing water for the cooling system, discharging 

blowdown water and sanitary effluent, and discharging waste heat to the atmosphere. Safety 

activities within the plant are discussed by the applicant in the FSAR portion of its application 

(STPNOC 2010c) and are reviewed by the NRC in its safety evaluation report (in progress). 

The following sections describe the operational activities, including operational modes 

(Section 3.4.1), plant-environment interfaces during operations (Section 3.4.2), the radioactive 

and nonradioactive waste management systems (Sections 3.4.3 and 3.4.4), and summarize the 

values of parameters likely to be experienced during operations (Section 3.4.5). 
Site Layout and Plant Description 

NUREG-1937 3-18 February 2011 

Table 3-2. Summary of Resource Commitments Associated with Building Proposed 

Units 3 and 4 

Resource Area Value Description 

All Resource Areas 7.5 years Duration of preconstruction and construction 

activities for two proposed units 

Land Use, Terrestrial Ecology, 

Cultural and Historic Resources 

(Site and Vicinity) 

540 ac Disturbed area footprint: 

300 ac permanently disturbed 

240 ac temporarily disturbed 

Hydrology-Groundwater 94 ft below plant 

grade 

1062 gpm 

491 gpm 

Excavation depth for which dewatering 

would be required 

Allowable monthly average groundwater 

withdrawal based on groundwater use 

permit 

Expected highest monthly groundwater use 

rate 

Socioeconomics, Transportation, 

Air Quality 

5950 workers 

9021 maximum 

number of 

workers onsite 

Peak construction workforce – month 26 

through month 35 of construction schedule 

• 1238 Units 1 and 2 operations staff 

• 733 Units 3 and 4 operations staff 

(approaching end of construction period) 

• 5950 construction workers 

• 1100 outage workers (e.g., refueling) 

Terrestrial Ecology, Nonradiological 

Health, Socioeconomics 

108 dBA 

69–84 dBA 

Peak noise level 

Noise level 400 ft from activity 

3.4.1 Description of Operational Modes 

The operational modes for proposed Units 3 and 4 considered in the assessment of operational 

impacts on the environment (Chapter 5) are normal operating conditions (including periodic 

testing of standby diesel generators) and emergency shutdown conditions. These are the 

nominal conditions under which maximum water withdrawal, heat dissipation, and effluent 

discharges occur. Cooldown, refueling, and accidents are alternate modes to normal plant 

operation during which water intake, cooling tower evaporation, water discharge, and radioactive 

releases may change from nominal conditions. There would be a shift in the operation of the two 

cooling systems from the MCR to the UHS cooling towers during these alternate modes.

3.4.2 Plant-Environment Interfaces During Operation 

This section describes the operational activities related to structures with an interface to the 

environment. 
 Site Layout and Plant Description 

February 2011 3-19 NUREG-1937 

3.4.2.1 Circulating Water System – Intakes, Discharges, Cooling Towers 

Waste heat is a byproduct of normal power generation at a nuclear power plant. The circulating 

water system (CWS) for the proposed Units 3 and 4 is similar to the CWS for STP Units 1 

and 2; it will transfer heat from the main condenser to the MCR, where the heat content of the 

circulating water is transferred to the ambient air primarily via radiation and evaporative cooling. 

During normal plant operation, the CWS would dissipate approximately 8.656 x 109

 Btu/hr for 

each unit, or 1.732 x 1010 Btu/hr for both units, of waste heat. In addition to its primary function 

as the UHS, the cooling towers are available as helper towers during normal operations. When 

used as helper towers, evaporation to the atmosphere would be 283 gpm; only half of the cells 

would be used during normal operations. The induced and natural evaporation from the MCR is 

dictated as a function of the air temperature, water temperature, humidity, and wind speed. In 

addition to evaporative losses, a small percentage of water is also lost in the form of droplets 

(drift) from the cooling tower; air impacts from cooling tower operation would also include visible 

plumes. STPNOC estimates that the two proposed units would require approximately 975 gpm 

of groundwater during normal operation and 3434 gpm during shorter-term peak demand 

periods as the source for makeup water for proposed Units 3 and 4 UHS, service water for the 

power plants, and water for sanitary and potable water systems (STPNOC 2010c). 

The RMPF operation would be variable, based on conditions in the MCR and conditions in the 

Colorado River. The RMPF was designed for a maximum diversion capacity of 1200 cfs; while 

it currently has the screening and pumping capacity installed for 600 cfs to meet the needs of 

Units 1 and 2, new pumps and screens would be installed at existing designated locations within 

the RMPF for an additional 600 cfs to meet the needs of proposed Units 3 and 4. The MCR 

discharge would periodically discharge water from the MCR to the Colorado River. Heated 

water would be discharged to the MCR through the MCR Cooling Water Discharge Structure 

(STPNOC 2010b). 

3.4.2.2 Landscape and Drainage 

The landscape and drainage would determine the path that precipitation takes on the land 

surface. In addition, the land cover, soil moisture content, and soil type would determine the 

rate of recharge to the subsurface. The MDC is the primary pathway that stormwater from 

around proposed Units 3 and 4 would leave the site. 

3.4.2.3 Essential Service Water System – Ultimate Heat Sink 

Proposed Units 3 and 4 would each have a six-cell mechanical draft cooling tower that serves 

as the UHS. The UHS mechanical draft cooling towers would receive makeup water from 

groundwater wells, with backup from the MCR. Evaporation to the atmosphere from the UHS 

cooling towers would be 1061 gpm during shutdown (emergency) conditions; when used in this 
Site Layout and Plant Description 

NUREG-1937 3-20 February 2011 

mode, all of the cells would be used. The UHS cooling towers would discharge to the MCR. 

Potential air impacts from cooling tower operation include visible plumes and drift. 

3.4.2.4 Emergency Diesel Generators 

Diesel generators would be installed on the site to provide a backup power source. Three 

generators per unit would be installed in the proposed reactor buildings. Diesel generators are 

intended to be used during off-normal conditions and, therefore, are safety related. Periodic 

testing of the generators to ensure working status contributes to combustion emissions to the 

atmosphere when the generators are running. 

3.4.3 Radioactive Waste-Management System 

Liquid, gaseous, and solid radioactive waste-management systems would be used to collect 

and treat the radioactive materials produced as byproducts of operating proposed Units 3 and 4. 

These systems would process radioactive liquid and gaseous effluents to maintain releases 

within regulatory limits and to levels as low as is reasonably achievable (ALARA) before 

releasing them to the environment. Waste-processing systems would be designed to meet the 

design objectives of 10 CFR Part 50, Appendix I (“Numerical Guides for Design Objectives and 

Limiting Conditions for Operation to Meet the Criterion ‘As Low as is Reasonably Achievable’ for 

Radioactive Material in Light-Water-Cooled Nuclear Power Reactor Effluents”). The radioactive 

waste-management systems would not be shared between the existing Units 1 and 2 and 

proposed Units 3 and 4. Radioactive materials in the reactor coolant would be the primary 

source of gaseous, liquid, and solid radioactive wastes in ABWRs. Radioactive fission products 

build up within the fuel as a consequence of the fission process. These fission products would 

be contained in the sealed fuel rods, but small quantities could escape the fuel rods into the 

reactor coolant. Neutron activation of the primary coolant system would also add radionuclides 

to the coolant. 

STPNOC proposed to make changes to the design of liquid, gaseous, and solid waste 

management systems included in the reference ABWR Design Control Document (GE 1997). 

The specific radioactive waste-management systems for the proposed two new units at the STP 

site are described in Chapter 11 of the FSAR (STPNOC 2010c). The change in the liquid 

waste-management system includes the use of mobile technology and eliminates the forced 

circulation concentrator system. The change in the gaseous waste management system 

involves changes to the charcoal adsorber system. The change in the solid waste-management 

system eliminates the solidification, incineration, and compacting process. The liquid and 

gaseous radioactive source terms for the ABWR design were provided by STPNOC in ER 

Tables 3.5-1 and 3.5-2 (STPNOC 2010b) and were based on its FSAR (STPNOC 2010c). 

The offsite dose calculation manual (ODCM) for the STP (STPNOC 2007) describes the 

methods and parameters used for calculating offsite radiological doses from liquid and gaseous 
 Site Layout and Plant Description 

February 2011 3-21 NUREG-1937 

effluents. The ODCM also describes the methodology for calculation of gaseous and liquid 

monitoring alarm/trip set points for release of effluents from STP. Operational limits for 

releasing liquid and gaseous effluents are also specified in the ODCM to ensure compliance 

with NRC regulations; a separate version of the ODCM will be prepared for Units 3 and 4. The 

systems used for processing liquid waste, gaseous waste, and solid waste are described in the 

following sections. 

3.4.3.1 Liquid Radioactive Waste-Management System 

Figure 3.5-1 in the ER (STPNOC 2010b) is a diagram of the liquid and solid waste-management 

systems. The Liquid Waste Management System (LWMS) is designed to control, collect, 

process, handle, store, and dispose of liquid radioactive waste generated as the result of normal 

operation and anticipated operational occurrences, including refueling operations 

(STPNOC 2010c). The LWMS is managed using several process trains consisting of tanks, 

pumps, ion exchangers, filters, and radiation monitors. Normal operations include processing of 

(1) reactor coolant system wastes, (2) floor drains and other wastes with potentially high 

suspended solid contents, (3) detergent wastes, and (4) chemical wastes. 

The LWMS routes batch discharges to the MCR. The discharge is monitored and 

administratively controlled to assure that it meets requirements of 10 CFR Part 20. Calculated 

dose to the maximally exposed individual (MEI) from liquid effluents is evaluated in 

Section 5.9.2. The LWMS is designed to comply with Regulatory Guide 1.143 guidance 

regarding liquid radwaste treatment systems. The LWMS is also designed to maintain the 

exposure of people in unrestricted areas ALARA (10 CFR Part 50 Appendix I). No subsystems 

of the LWMS and the radwaste building that house the LWMS are shared between proposed 

Units 3 and 4 (STPNOC 2010b). Units 3 and 4 will each have their own independent LWMS. 

3.4.3.2 Gaseous Waste-Management System 

The gaseous waste-management system (GWMS) functions to collect, process, and discharge 

radioactive gaseous wastes. The GWMS is illustrated in Figure 3.5-2 of the ER 

(STPNOC 2010b). Gaseous radionuclides would be generated during normal operation of Units 

3 and 4. They would include gaseous fission products and gaseous radionuclides formed by 

neutron activation of the reactor coolant and contained gases. These gases are retained in the 

plant systems and removed in a controlled fashion through the GWMS, which collects waste 

from multiple sources and delays its release to allow short-lived radionuclides to decay. The 

remaining gaseous radionuclides are released in a controlled manner to the environment 

through the plant stack, a monitored release point. Radioisotopes of iodine and the noble gases 

xenon and krypton are created as fission products within the fuel during operation. Some of 

these gases escape to the reactor coolant system through cladding defects then subsequently 

decay to stable isotopes. Some of these gases are released to the environment via plant 

ventilation or are delayed by activated carbon adsorbers and then released through the GWMS. 
Site Layout and Plant Description 

NUREG-1937 3-22 February 2011 

In addition, various neutron activation products, such as argon-41, are formed directly in the 

reactor coolant during operation and are also delayed by the activated carbon adsorbers, and 

then released through the GWMS. 

Major process equipment of the GWMS includes the following: 

1. process piping starting from the final steam dilution jets of the main condenser evacuation 

system (not a part of the off-gas system) 

2. integral recombiners, including a preheater section, a recombiner section, and a condenser 

section 

3. cooler-condensers 

4. activated charcoal adsorbers 

5. high efficiency particulate air filter 

6. monitoring instrumentation, and 

7. process instrumentation and controls. 

The GWMS is housed in a reinforced concrete structure to provide adequate shielding. The 

charcoal adsorbers are installed in a temperature-monitored and controlled vault, which is 

located in the turbine building to minimize piping. 

The GWMS processes and controls the release of gaseous radionuclides to the environs to 

maintain the exposure of people in unrestricted areas ALARA (10 CFR Part 50 Appendix I). 

Calculated doses to the MEI from gaseous effluents are evaluated in Section 5.9.2. 

3.4.3.3 Solid Radioactive Waste Management System 

The solid radioactive waste-management system (SWMS) treats, stores, packages, and 

disposes of dry or wet solids. The SWMS is illustrated in Figure 3.5-1 of the ER 

(STPNOC 2010b). The SWMS Process Flow Diagram is provided in Figure 11.2-1 of the FSAR 

(STPNOC 2010c). Solid radioactive waste can be either dry or wet solids, and the source can 

be an operational activity, maintenance, or another function. Non-fuel solid wastes are 

generated from separating and treating radioactive material from gases and liquids and from 

removing contaminated material from various reactor areas. Solid wastes also consist of 

reactor components, equipment, and tools removed from service, as well as contaminated 

protective clothing, rags, and other trash generated from plant design modifications, operations, 

and maintenance activities. The SWMS is designed to handle both normal and anticipated 

operational occurrences. The annual total estimated volume of solid waste to be shipped would 

be about 475 cubic meters per year (m3

/yr) (STPNOC 2010b). 
 Site Layout and Plant Description 

February 2011 3-23 NUREG-1937 

Solid wastes may be shipped to a waste processor for volume reduction before disposal at a 

licensed disposal facility. Wet solid wastes include spent resins and sludge from powdered 

resins and filter backwashing. Spent resins and filters are typically dewatered before packaging 

for shipment to a licensed offsite processing or disposal facility. The storage and transportation 

of used reactor fuel is discussed in Chapter 6. 

3.4.4 Nonradioactive Waste Management Systems 

The following sections provide descriptions of the nonradioactive waste systems proposed for 

the two new units. This category of nonradioactive effluent includes gaseous emissions, liquids, 

hazardous waste, mixed waste, and solids. 

3.4.4.1 Solid Waste Management 

Activated sludge from the existing Units 1 and 2 has previously been disposed by land 

application at a rate of 30,000 to 40,000 gallons per year (STPNOC 2010e). Currently, 

activated sludge from the West Sanitary Waste Treatment System (WSWTS) and Nuclear 

Training Facility (NTF) system is dewatered onsite and shipped offsite as Texas Class 2 

industrial waste to a permitted landfill operated by Republic Waste Services in Fresno, Texas 

(STPNOC 2010e). The increased sludge that would be generated by the operation of two 

additional units would be treated in a similar manner to the sludge from operation of Units 1 

and 2 (STPNOC 2010e). 

Nonradioactive solid wastes that would be created during the construction and operation of 

proposed Units 3 and 4 include industrial refuse such as paper, metal, wood, and batteries. 

STPNOC has a recycling program for metal and paper waste and ships batteries to a registered 

battery recycling facility. These recycling efforts would continue with the addition of Units 3 

and 4. Non-recyclable solid waste would be deposited in an onsite landfill consistent with Texas 

Commission on Environmental Quality (TCEQ) regulations or shipped to an offsite landfill 

(STPNOC 2010b). 

STPNOC is currently a small quantity generator of hazardous waste, based on the amount of 

waste generated by Units 1 and 2 (STPNOC 2010b). This status could be upgraded with the 

addition of the two new units. The treatment, storage, and disposal of hazardous wastes 

generated at the two new units would be managed and disposed in the same appropriate 

manner as the existing units’ hazardous waste. 

3.4.4.2 Liquid Waste Management 

Water chemistry for various plant water uses would be controlled with the addition of biocides, 

algaecides, corrosion inhibitors, pH buffering, scale inhibitors, and dispersants. Chemical and 

biocides similar to those currently used for existing Units 1 and 2 are expected to be used for 

proposed Units 3 and 4. Table 3-3 provides a list of water treatment chemicals currently used 
Site Layout and Plant Description 

NUREG-1937 3-24 February 2011 

for STP Units 1 and 2 to treat biofouling and algae and to provide for pH buffering, corrosion 

inhibition, scale inhibition, and silt dispersion. Chemical and biocidal additives and waste 

streams from various water treatment processes and drains are returned to the MCR where 

they are subjected to dilution, aeration, vaporization, and chemical reactions. In addition, a 

dedicated drain system collects waste water from the turbine building, the reactor building, the 

hot machine shop, and the control building to separate any solids from the liquid effluent for 

deposition into dual settling basins. The nonradioactive effluents are then discharged into the 

MCR. Water from the MCR may be discharged to the Colorado River subject to the limitations 

of STPNOC’s existing Texas Pollutant Discharge Elimination System (TPDES) permit 

(STPNOC 2010b). Impacts to surface water quality are discussed in Sections 4.2.3.1 and 

5.2.3.1, respectively. 

Table 3-3. Representative Water Treatment Chemicals Used for STP Units 1 and 2 

Ammonium bisulfite Molluscide (quaternary amine) 

Antifoam Phosphate 

Biocide (sodium bromide) Polymers 

Boric Acid Sodium bisulfite 

Calcium hypochlorite Sodium chloride 

Coagulant Sodium hydroxide 

Corrosion Inhibitors Sodium hypochlorite 

(ethanolamine, sodium metaborate, sodium nitrite) Sulfuric acid 

Dispersant Tolytriazole 

Hydrazine Zinc 

Lithium Hydroxide 

Source: STPNOC 2010b 

STPNOC currently uses two sanitary waste systems that are in compliance with State 

regulations and the Federal Water Pollution Control Act (Clean Water Act). One system serves 

the existing Units 1 and 2, WSWTS, and the other system serves the NTF. Both systems would 

be replaced or upgraded to accommodate the expansion of the facilities by the addition of 

Units 3 and 4 (STPNOC 2010e). The WSWTS will be designed to treat sanitary waste at a rate 

of 300,000 gallons per day, and the NTF system will be designed to treat sanitary waste at a 

rate of 100,000 gallons per day (STPNOC 2010b). 

Liquid waste from sanitary treatment systems would use the existing outfalls for discharge of 

effluents from the new WSWTS and NTF systems to the MCR. A new or amended permit 

would need to be submitted to TCEQ to comply with water quality requirements for the added 

capacity for treatment, discharge, and monitoring of liquid wastes of the new systems 

(STPNOC 2010b). 
 Site Layout and Plant Description 

February 2011 3-25 NUREG-1937 

Other industrial liquid wastes such as oil, diesel fuel, and antifreeze are collected and sent to 

recycling centers. Non-recyclable liquid wastes such as paint, electrohydraulic fluid, and 

solvents are shipped offsite to appropriate waste collection facilities (STPNOC 2010b). 

3.4.4.3 Gaseous Waste Management 

STPNOC currently has gaseous emissions, primarily from diesel generators and the combustion 

turbine generator, that are subject to air permits issued by the TCEQ. The addition of 

Units 3 and 4 would require additional diesel and combustion turbine generators with attendant 

emissions regulated under an amended or new TCEQ permit. No other sources for gaseous 

emissions are currently planned at the STP site (STPNOC 2010b). 

3.4.4.4 Hazardous and Mixed Waste Management 

Mixed wastes contain both hazardous and low-level radioactive waste. Small amounts of mixed 

waste could be generated during maintenance, refueling, and laboratory activities. STPNOC 

does not expect Units 3 and 4 to generate mixed waste in substantial quantities; if mixed waste 

is generated, then it is expected to be 0.5 m3

/yr or less. The mixed waste from Units 3 and 4 

would be handled and managed similarly to Units 1 and 2, in accordance with the applicable 

Federal and State regulations (STPNOC 2010b). 

3.4.5 Summary of Resource Parameters During Operation 

Table 3-4 provides a list of the significant resource commitments involved in operating Units 3 

and 4 that are relevant to more than one resource evaluation. The values in this table, 

combined with the affected environment described in Chapter 2, provide a part of the basis for 

the operational impacts assessed in Chapter 5. These values were stated in the ER (STPNOC 

2010b) and supplemental RAI responses (STPNOC 2009), and the review team has determined 

that the values are not unreasonable. 

Table 3-4. Resource Commitments Associated with Operation of Proposed STP Units 3 and 4 

Resource Area 

Normal 

Operating 

Condition 

Maximum 

Condition Description 

Socioeconomics 959 workers 2059 workers Normal condition for two units; 

Maximum occurs during refueling 

outages lasting 15 to 35 days; 

Table G-2 of this EIS indicates 

1100 workers for an outage 

Terrestrial Ecology, Radiological 

Health, Socioeconomics 

140 ft 140 ft Height of tallest building 

(Turbine building) 

 249 ft 249 ft Height of tallest structure 

(vent stack) 
Site Layout and Plant Description 

NUREG-1937 3-26 February 2011 

Table 3-4. (contd) 

Resource Area 

Normal 

Operating 

Condition 

Maximum 

Condition Description 

Hydrology – Groundwater 47gpm 491 gpm Range of monthly groundwater 

use during initial testing 

 975 gpm 3434 gpm Groundwater withdrawal rate for 

all systems combined 

 50 gpm 91 gpm Groundwater withdrawal rate for 

makeup water 

 40 gpm 140 gpm Groundwater withdrawal rate for 

potable water 

 885 gpm 3203 gpm Groundwater withdrawal rate for 

UHS makeup water 

Hydrology – Surface Water 21,600 gpm 

long-term 

average basis 

for 93% load 

factor 

23,190 gpm 

for 100% load 

factor 

Water obtained from Colorado 

River, precipitation and 

groundwater discharge to MCR 

 22,799 gpm 47,489 gpm Total required Colorado River 

water to MCR 

 23,190 gpm 49,000 gpm MCR forced evaporation rate 

 0 gpm 138,240 gpm MCR blowdown to Colorado River 

Hydrology – Groundwater, 566 gpm 2122 gpm UHS evaporation rate 

Hydrology – Surface Water, 5 gpm 10 gpm UHS drift rate 

Terrestrial Ecology, 

Meteorology/Air Quality

24 gpm 13 gpm 

(under 

maximum 

water use 

condition) 

UHS seepage 

Hydrology – Groundwater, 

Hydrology – Surface Water, 

290 gpm 1058 gpm Blowdown rate to MCR 

Terrestrial Ecology 391 gpm 1511 gpm Plant effluent discharge to MCR 

Aquatic Ecology <0.5 fps 0.5 fps Intake screen approach velocity 

Terrestrial Ecology, 

Socioeconomics, 

65 dBA Cooling tower sound level at 50 ft 

Nonradiological Health 51 dBA Cooling tower sound level at 400 ft

Radiological Health, 

Transportation, Need for Power 

3926 MW(t) Rated and design core thermal 

power of an ABWR 

1356 MW(e) Gross Electrical Output and 

Nominal rating of turbinegenerator for one unit 

56 MW(e) Internal load per unit 
 Site Layout and Plant Description 

February 2011 3-27 NUREG-1937 

Table 3-4. (contd) 

Resource Area 

Normal 

Operating 

Condition 

Maximum 

Condition Description 

Radiological Health 95 percent Expected annual capacity factor 

Meteorology/Air Quality 1.732 × 1010

Btu/hr 

1.732 × 1010

Btu/hr 

Waste heat to atmosphere 

55.5 ft 55.5 ft UHS cooling-tower height 

Sources: STPNOC 2010b, 2009 

3.5 References 

10 CFR Part 20. Code of Federal Regulations, Title 10, Energy, Part 20, “Standards for 

Protection against Radiation.” 

10 CFR Part 50. Code of Federal Regulations, Title 10, Energy, Part 50, “Domestic Licensing of 

Production and Utilization Facilities.” 

10 CFR Part 51. Code of Federal Regulations, Title 10, Energy, Part 51, “Environmental 

Protection Regulations for Domestic Licensing and Related Regulatory Functions.” 

10 CFR Part 52. Code of Federal Regulations, Title 10, Energy, Part 52, “Licenses, 

Certifications, and Approvals for Nuclear Power Plants.” 

62 FR 25800. May 12, 1997. “Standard Design Certification for the U.S. Advanced Boiling 

Water Reactor Design.” Federal Register. U.S. Nuclear Regulatory Commission. 

66 FR 65256. December 18, 2001. “National Pollutant Discharge Elimination System: 

Regulations Addressing Cooling Water Intake Structures for New Facilities; Final Rule” Federal 

Register. U.S. Environmental Protection Agency. 

72 FR 37107. July 9, 2007. “National Pollutant Discharge Elimination System –Suspension of 

Regulations Establishing Requirements for Cooling Water Intake Structures at Phase II Existing 

Facilities.” Federal Register. Environmental Protection Agency. 

72 FR 57416. October 9, 2007. “Limited Work Authorizations for Nuclear Power Plants; Final 

Rule.” Federal Register. U.S. Nuclear Regulatory Commission. 

General Electric (GE). 1997. ABWR Design Control Document, Tier 2 Manual. Revision 4. 

National Environmental Policy Act of 1969, as amended (NEPA). 42 USC 4321, et seq.
Site Layout and Plant Description 

NUREG-1937 3-28 February 2011 

South Texas Project Nuclear Operating Company (STPNOC). 2007. Offsite Dose Calculation 

Manual (ODCM), Revision 15, South Texas Project. Accession No. ML081300728. 

South Texas Project Nuclear Operating Company (STPNOC). 2008. Letter from Gregory 

Gibson, STPNOC, to NRC, dated July 15, 2008, regarding Response to Request for Additional 

Information. Accession No. ML082040684. 

South Texas Project Nuclear Operating Company (STPNOC). 2009. Letter from Scott Head, 

STPNOC, to NRC, dated September 28, 2009, regarding Response to Request for Additional 

Information. Accession No. ML092730285. 

South Texas Project Nuclear Operating Company (STPNOC). 2010a. Letter from Scott Head, 

STPNOC, to the U.S. Army Corps of Engineers Galveston District, dated March 9, 2010, 

regarding South Texas Project Units 3 and 4 Application for Department of Army Permit. 

Accession No. ML102700237. 

South Texas Project Nuclear Operating Company (STPNOC). 2010b. South Texas Project 

Units 3 and 4 Combined License Application, Part 3, Environmental Report. Revision 4, Bay 

City, Texas. Accession No. ML102860592. 

South Texas Project Nuclear Operating Company (STPNOC). 2010c. South Texas Project 

Units 3 and 4 Combined License Application, Part 2, Final Safety Analysis Report. Revision 4, 

Bay City, Texas. Accession No. ML102860517. 

South Texas Project Nuclear Operating Company (STPNOC). 2010d. ABWR STP Aircraft 

Impact Assessment (AIA) Amendment. Revision 3, Bay City, Texas. Accession No 

ML102870017. 

South Texas Project Nuclear Operating Company (STPNOC). 2010e. Letter from Mark 

McBurnett, STPNOC, to NRC, dated September 9, 2010, regarding Additional Information 

Regarding Draft Environmental Impact Statement. Accession No. ML102600127. 

U.S. Nuclear Regulatory Commission (NRC). 1986. Final Environmental Statement related to 

the operation of South Texas Project, Units 1 and 2. NUREG-1171, Washington, D.C. 

U.S. Nuclear Regulatory Commission (NRC). 1994. Final Safety Evaluation Report Related to 

the Certification of the Advanced Boiling Water Reactor. NUREG-1503, Washington, D.C. 

U.S. Nuclear Regulatory Commission (NRC). 2001. Design Guidance for Radioactive Waste 

Management Systems, Structures, and Components Installed in Light-Water-Cooled Nuclear 

Power Plants. Regulatory Guide 1.143, Washington, D.C. 
February 2011 4-1 NUREG-1937 

4.0 Construction Impacts at the Proposed Site 

This chapter examines the environmental issues associated with building the proposed Units 

3 and 4 at the South Texas Project Electric Generating Station (STP) site as described in the 

application for combined licenses (COLs) submitted by STP Nuclear Operating Company 

(STPNOC). As part of its application, STPNOC submitted (1) an Environmental Report (ER) 

(STPNOC 2010a), which discusses the environmental impacts of constructing the new nuclear 

units and provides information used as the basis for the environmental review, and (2) a Final 

Safety Analysis Report (STPNOC 2010b), which addresses safety aspects of construction and 

operation. 

As discussed in Section 3.3 of this environmental impact statement (EIS), the U.S. Nuclear 

Regulatory Commission’s (NRC’s) authority related to building new nuclear units is limited to 

“activities that have a reasonable nexus to radiological health and safety and/or common 

defense and security” (72 FR 57426). The NRC has defined “construction” according to the 

bounds of its regulatory authority. Many of the activities required to build a nuclear power plant 

do not fall within the NRC’s regulatory authority and, therefore, are not “construction” as defined 

by the NRC. Such activities are referred to as “preconstruction” activities in 10 CFR 51.45(c). 

The NRC staff evaluates the direct, indirect, and cumulative impacts of the construction 

activities that would be authorized with the issuance of a COL. The environmental effects of 

preconstruction activities (e.g., clearing and grading, excavation, and erection of support 

buildings) are included as part of this EIS in the evaluation of cumulative impacts.

As described in Section 1.1.3, the U.S. Army Corps of Engineers (Corps) is a cooperating 

agency on this EIS consistent with the updated Memorandum of Understanding (MOU) signed 

with the NRC (Corps and NRC 2008). The NRC and the Corps established this cooperative 

agreement because both agencies have concluded it is the most effective and efficient use of 

Federal resources in the environmental review of a proposed new nuclear power plant. The 

goal of this cooperative agreement is the development of one EIS that provides all the 

environmental information and analyses needed by the NRC to make a license/permit decision 

and all the information needed by the Corps to perform analyses, draw conclusions, and make a 

permit decision in the Corps’ Record of Decision (ROD) documentation. To accomplish this 

goal, the environmental review described in this EIS was conducted by a joint NRC and Corps 

team. The review team was composed of NRC staff and its contractors and staff from the 

Corps. 

The information needed by the Corps includes information to perform (1) analyses to determine 

that the proposed action is the least environmentally damaging practicable alternative (LEDPA), 

and (2) its public interest assessment. To perform the public interest assessment, the Corps 

considers the following public interest factors: conservation, economics, aesthetics, general 
Construction Impacts at the Proposed Site 

NUREG-1937 4-2 February 2011 

environmental concerns, wetlands, historic and cultural resources, fish and wildlife values, flood 

hazards, floodplain values, land use, navigation, shore erosion and accretion, recreation, water 

supply, water quality, energy needs, safety, food and fiber production, and mineral needs.

Many of the impacts the Corps must address in its LEDPA analysis are the result of 

preconstruction activities. Also, most of the activities conducted by a COL applicant that would 

require a permit from the Corps would be preconstruction activities. On June 4, 2009, with 

subsequent submittal on October 28, 2009, STPNOC submitted a Permit Determination 

Request to the Corps Galveston District for activities associated with constructing and operating 

Units 3 and 4 (STPNOC 2009a). On November 10, 2009, the Corps notified STPNOC that the 

proposed project would require a U.S. Department of the Army permit pursuant to Section 404 

of the Federal Water Pollution Control Act (Clean Water Act) and Section 10 of the Rivers and 

Harbors Act of 1899 (Corps 2009a). On March 9, 2010, STPNOC submitted a Department of 

the Army Permit application (STPNOC 2010c) to the Galveston District of the Corps for activities 

associated with constructing and operating Units 3 and 4. 

While both NRC and the Corps must meet the requirements of the National Environmental 

Policy Act of 1969, as amended (NEPA) (42 USC 4321, et seq.), both agencies also have 

mission requirements that must be met in addition to the NEPA requirements. The NRC‘s 

regulatory authority is based on the Atomic Energy Act of 1954, as amended (42 USC 2011, et 

seq.). The Corps’ regulatory authority related to the proposed action is based on Section 10 of 

the Rivers and Harbors Act (33 USC 403, et seq.), which prohibits the obstruction or alteration 

of navigable waters of the United States without a permit from the Corps, and Section 404 of the 

Clean Water Act (33 USC 1344, et seq.), which prohibits the discharge of dredged or fill material 

into waters of the United States without a permit from the Corps. Therefore, the applicant may 

not commence preconstruction or construction activities in jurisdictional waters, including 

wetlands, without a Corps permit. The permit would typically be issued following the Corps’ 

evaluation and public feedback in the form of public comments on its draft environmental 

review. Because the Corps is a cooperating agency under the MOU for this EIS, the Corps’ 

decision of whether to issue a permit will not be made until after this final EIS is issued. 

The collaborative effort between the NRC and the Corps in presenting their discussion of the 

environmental effects of building the proposed project, in this chapter and elsewhere, must 

serve the needs of both agencies. Consistent with the MOU, the staffs of the NRC and the 

Corps collaborated (1) in the review of the COL application and information provided in 

response to requests for additional information (developed by the NRC and the Corps) and 

(2) in the development of the EIS. NRC regulations (10 CFR 51.45(c)) require that the impacts 

of preconstruction activities be addressed by the applicant as cumulative impacts in its ER. 

Similarly, the NRC’s analysis of the environmental effects of preconstruction activities on each 

resource area would be addressed as cumulative impacts, normally presented in Chapter 7. 

However, because of the collaborative effort between the NRC and the Corps in the 
 Construction Impacts at the Proposed Site 

February 2011 4-3 NUREG-1937 

environmental review, the combined impacts of construction activities that would be authorized 

by the NRC with its issuance of COLs and the preconstruction activities are presented in this 

chapter. For each resource area, the NRC also provides an impact characterization solely for 

construction activities that meets the NRC’s definition of construction at 10 CFR 50.10(a). 

Thereafter, both the assessment of the impacts of 10 CFR 50.10(a) construction activities and 

the assessment of the combined impacts of construction and preconstruction are used in the 

description and assessment of cumulative impacts in Chapter 7. 

In addition to guidance provided in NUREG-1555, Environmental Standard Review Plan (NRC 

2000), staff used guidance provided in NRC Staff Memorandum Addressing Construction and 

Preconstruction Activities, Greenhouse Gas Issues, General Conformity Determinations, 

Environmental Justice, Need for Power, Cumulative Impact Analysis, and Cultural/Historical 

Resources Analysis Issues In Environmental Impact Statements (NRC 2010) to address 

preconstruction and construction activities and impacts. For most environmental resource areas 

(e.g., terrestrial ecology), the impacts are not the result of either solely preconstruction or solely 

construction activities. Rather, the impacts are attributable to a combination of preconstruction 

and construction activities. For most resource areas, the majority of the impacts would occur as 

a result of preconstruction activities. 

This chapter is divided into 13 sections. In Sections 4.1 through 4.10, the review team 

evaluates the potential impacts on land use, meteorology and air quality, water use and quality, 

terrestrial and aquatic ecosystems, socioeconomics, environmental justice, historic and cultural 

resources, nonradiological and radiological health effects, nonradioactive waste, and applicable 

measures and controls that would limit the adverse impacts of building the new units. An impact 

category level – SMALL, MODERATE, or LARGE – of potential adverse impacts has been 

assigned by the review team for each resource area using the definitions for these terms 

established in Chapter 1. In some resource areas, for example, in the socioeconomic area 

where the impacts of taxes are analyzed, the impacts may be considered beneficial and would 

be stated as such. The review team’s determination of the impact category levels is based on 

the assumption that the mitigation measures identified in the ER or activities planned by various 

State and county governments, such as infrastructure upgrades (discussed throughout this 

chapter), are implemented. Failure to implement these upgrades might result in a change in the 

impact category level. Possible mitigation measures of adverse impacts, where appropriate, are 

presented in Section 4.11. A summary of the construction impacts and the proportional 

distribution of impacts based on construction and preconstruction is presented in Section 4.12. 

Citations for the references cited in this chapter are listed in Section 4.13. The technical 

analyses provided in this chapter support the results, conclusions, and recommendations 

presented in Chapters 7, 9, and 10. 

The review team’s evaluation of the impacts of building Units 3 and 4 draws on information 

presented in STPNOC’s ER and supplemental documents, and the Corps’ permitting 

documentation, as well as other government and independent sources. 
Construction Impacts at the Proposed Site 

NUREG-1937 4-4 February 2011 

4.1 Land-Use Impacts 

This section provides information on land-use impacts associated with building Units 3 and 4 at 

the STP site. Topics discussed include land-use impacts at the STP site and in the vicinity of 

the site and land-use impacts in transmission line corridors and other offsite areas. 

4.1.1 The Site 

Proposed Units 3 and 4 would be located northwest of existing Units 1 and 2. The proposed 

location for Units 3 and 4 is entirely within the existing STP site. There are no zoning 

regulations currently applicable to the STP site (STPNOC 2010a). 

All project activities for building Units 3 and 4, including ground-disturbing activities, would occur 

within the existing STP site boundary and on land that was previously disturbed during building 

of Units 1 and 2. The area that would be affected on a long-term basis as a result of permanent 

facilities at the STP site would be approximately 300 ac (STPNOC 2010a). Permanent impacts 

include disturbance to areas proposed for the power block for Units 3 and 4; the switchyard; the 

cooling tower area; the heavy haul road; and the intake, pipeline, and discharge areas for the 

cooling water system. These activities would result in a permanent land-use change from open 

space. An additional approximately 240 ac would be disturbed for temporary facilities including 

a concrete batch plant, material storage areas, laydown areas, parking areas, borrow areas, 

and spoils storage (STPNOC 2010a). These activities would result in a temporary land-use 

change; STPNOC plans to restore temporarily disturbed areas after completion. STPNOC 

states in its ER that all preconstruction and construction activities would be conducted in 

accordance with Federal, State, and local regulations (STPNOC 2010a). 

Parking lots, soil borrow areas, and storage areas for spoils would generally be west of the 

Unit 3 and 4 construction area. The heavy haul road would be constructed by STPNOC from 

the Unit 3 and 4 power block area to the existing road to the barge slip. The heavy haul road 

would be approximately 2.5 mi long and 50 ft wide (STPNOC 2010a) and would result in a 

permanent land use change from open space. Temporary laydown areas would be located to 

the north and south of the Unit 3 and 4 power block area, resulting in a temporary land use 

change. STPNOC plans to restore temporarily disturbed areas after completion of the project. 

With the exceptions of the barge slip expansion, dredging of the Colorado River’s navigation 

channel if needed, and upgrade of the Reservoir Makeup Pumping Facility (RMPF), most of the 

major project activities would not take place within a floodplain. The existing rail spur to the 

STP site would be upgraded, but there would be no associated land-use impacts. The new 

switchyard to serve Units 3 and 4 would be located approximately 650 ft north of Units 3 and 4 

(STPNOC 2010a). 
 Construction Impacts at the Proposed Site 

February 2011 4-5 NUREG-1937 

Approximately 162 ac of natural and man-made wetlands are on the STP site (STPNOC 

2010a). The man-made wetlands totaling 110 ac (the Texas Prairie Wetlands Project [TPWP]) 

are located approximately 1800 ft north of the Essential Cooling Pond (ECP). These wetlands 

would not be disturbed by project activities. The Corps has identified 29 smaller wetland areas 

totaling 17.6 ac on the STP site; one of the wetlands (WET001) is near the northwest corner of 

proposed Unit 4 (Corps 2009b). In addition, Kelly Lake is 34 ac. STPNOC would avoid these 

sites while building facilities (STPNOC 2010a). 

The only Unit 3 and 4 facilities that would be located in the Colorado River floodplain are those 

that would be shared with and have already been constructed for use by Units 1 and 2. 

Therefore, there would be minimal or no additional land-use impacts to these areas. These 

facilities are the RMPF, the Main Cooling Reservoir (MCR) blowdown discharge pipes, the MCR 

spillway discharge structure, and the barge facility. The remainder of the Unit 3 and 4 facilities 

would be constructed in areas located above the elevation of the floodplain (STPNOC 2010a). 

Material from any dredging activities in or adjacent to the Colorado River would be placed in a 

man-made upland dredge material disposal area located between the MCR and the Colorado 

River (STPNOC 2010a). 

After completion of Units 3 and 4, STPNOC plans to restore areas used for project support by 

grading, landscaping, and planting to enhance the overall site appearance. Previously 

vegetated areas cleared for temporary facilities would be revegetated, and harsh topographical 

features created during the project would be contoured to match the surrounding areas 

(STPNOC 2010a). Because a relatively small percentage of uplands and no wetlands at the 

STP site would be permanently converted to new land-use categories, the land-use impacts of 

building Units 3 and 4 would be minor. 

Based on information provided by STPNOC and the review team’s independent review, the 

review team concludes that the combined land-use impacts of construction and preconstruction 

activities would be SMALL, and no further mitigation would be warranted. Based on the above 

analysis, and because NRC-authorized construction activities represent only a portion of the 

analyzed activities; the NRC staff concludes that the impacts of NRC-authorized construction 

activities would be SMALL. 

4.1.2 Transmission Line Corridors and Offsite Areas 

As discussed in Chapter 3, no new offsite transmission corridors or expansion of existing 

corridors are planned for proposed Units 3 and 4. The power transmission system for the new 

units would not require new transmission lines or corridors, but would use five of the nine 

345-kV transmission lines that currently connect to existing STP Units 1 and 2 (STPNOC 

2010a); a portion of the system would be upgraded, perhaps necessitating the use of board 

roads within wetlands, resulting in temporary impacts. Activities associated with building the 
Construction Impacts at the Proposed Site 

NUREG-1937 4-6 February 2011 

new onsite switchyard and connecting transmission lines would occur in areas previously 

disturbed during site development activities associated with Units 1 and 2 (STPNOC 2010a). 

A few other offsite land-use changes in the region would be expected as a result of project 

activities. STPNOC would construct a new Emergency Operations Facility (EOF) in Bay City, 

Texas, where the new offices for Units 3 and 4 would be located (STPNOC 2010a). Possible 

changes include the conversion of some land in surrounding areas to temporary or permanent 

housing developments (e.g., recreational vehicle parks, apartment buildings, single-family 

condominiums and homes, and/or manufactured home parks) and retail development to serve 

construction workers. Additional information on roads, housing, and recreation-related 

infrastructure impacts is in Section 4.4.4. While the precise land-use impacts cannot be 

predicted, the review team determined that any land-use changes would not be inconsistent 

with local zoning and land-use plans. The land-use impacts of project activities in transmission 

line corridors and offsite areas would be minor, and additional mitigation would not be 

warranted. 

Based on information provided by STPNOC and the review team’s independent evaluation, the 

review team concludes that the combined offsite land-use impacts from preconstruction and 

construction activities related to transmission corridors and the new EOF would be SMALL, and 

that no additional mitigation would be warranted. NRC’s 2007 Limited Work Authorization 

(LWA) rule (72 FR 57426) specifically indicates that transmission lines and other offsite 

activities are not included in the definition of construction. Therefore, the NRC staff concludes 

that there would be no offsite land-use impacts associated with NRC-authorized construction 

activities. 

4.2 Water-Related Impacts 

Water-related impacts involved in building a nuclear power plant are similar to impacts that 

would be associated with building of large industrial projects and are not much different than 

those experienced during the building of STP Units 1 and 2. Prior to initiating building activities, 

including any site-preparation work, STPNOC would be required to obtain the appropriate 

authorizations regulating alterations to the hydrological environment. The following is a list of 

the hydrological-related authorizations, permits, and certifications potentially required from 

Federal, State, regional, and local agencies. Additional detail regarding the items below is 

contained in Appendix H. 

• Rivers and Harbors Appropriation Act of 1899 Section 10 Permit. This permit is issued by 

the Corps to regulate structures and/or work in navigable waters of the United States such 

as the Colorado River. 

• Clean Water Act Section 401 Certification. This certification is issued by the State of Texas 

and ensures that the project does not conflict with State water-quality standards. 
 Construction Impacts at the Proposed Site 

February 2011 4-7 NUREG-1937 

• Clean Water Act Section 402(p) National Pollutant Discharge Elimination System (NPDES) 

Construction and Industrial Stormwater Permits. These permits would regulate point source 

discharges to surface water. U.S. Environmental Protection Agency (EPA) stormwater 

regulations established requirements for stormwater discharges from various activities, 

including building activities. EPA has delegated the authority for administering the NPDES 

program in the State of Texas to the Texas Commission on Environmental Quality (TCEQ), 

which issues the Texas Pollutant Discharge Elimination System (TPDES) permits. 

• Clean Water Act Section 404 Permit. The Department of the Army permit is required for the 

discharge of dredge and/or fill material into waters of the United States, including wetlands. 

• Public Drinking Water System Permit. This permit is issued by the TCEQ to ensure a safe 

drinking water supply for public use. The permit addresses water sources, storage, and 

distribution and ensures that the State drinking quality standards are met. STPNOC would 

need to modify its existing permit for the planned expansion. 

• Groundwater Well Drilling and Operating Permits. These permits are issued by the Coastal 

Plains Groundwater Conservation District (CPGCD) to ensure that groundwater use 

complies with the rules of the CPGCD (CPGCD 2009) and Texas State law (i.e., Texas 

Water Code Chapter 35 “Groundwater Studies” and Water Code Chapter 36 “Groundwater 

Conservation Districts”). 

4.2.1 Hydrological Alterations 

Building the proposed Units 3 and 4 at STP would alter several surface-water bodies and some 

of the aquifers underlying the site. Surface-water bodies that may be affected include the 

sloughs located on the site (including Little Robbins Slough), the MCR, the existing Main 

Drainage Channel (MDC) in the proposed area where Units 3 and 4 would be located, and 

proposed site drainage channels that flow to the Colorado River and to the West Branch of the 

Colorado River. Groundwater aquifers that may be affected include the Upper and Lower 

Shallow Aquifers into which the slurry wall, excavation, and fill would penetrate, and the Deep 

Aquifer in which one or more additional production wells would be installed. 

As stated in Section 3.2, an approximately 2-mi-long heavy haul road would be built from the 

barge slip to the proposed location of Units 3 and 4. There is a potential for alteration of 

drainage and recharge patterns on the STP site because of the heavy haul road. 

Chapter 2 describes the modification to the RMPF needed to support the operation of the 

proposed units. The installation of the new pumps in the existing RMPF would not affect the 

Colorado River. The intake screens that require refurbishment or replacement can be lifted out 

and placed back in without substantial alteration of the intake structure. Dredging would occur 

in the RMPF forebay, in the Colorado River along the intake screens, and in the barge slip area 

as needed to remove accumulated sediment. Dredging would be performed in accordance with 
Construction Impacts at the Proposed Site 

NUREG-1937 4-8 February 2011 

existing or future permits issued by the Corps (STPNOC 20010a). The impact on the Colorado 

River from these activities would be temporary and limited in extent to the immediate vicinity of 

the structures. 

As stated in Section 3.2, erection of new transmission line towers would occur on existing pads. 

STPNOC stated that it would implement erosion control measures for areas that may be 

adjacent to surface water bodies to minimize sediment and other pollutant discharge. As stated 

in Section 3.2, the refurbishment of the existing railroad on the STP site would be limited to 

ballast placement and replacement of some rail sections. Implementation of best management 

practices (BMPs) should minimize alterations to wetlands and surface-water bodies near the 

STP site. 

4.2.2 Water-Use Impacts 

STPNOC has proposed no surface water use for building the proposed Units 3 and 4. 

STPNOC currently holds a groundwater use permit to withdraw from the Deep Aquifer an 

average of approximately 1860 gpm (3000 ac-ft/yr) (CPGCD 2008). This operating permit 

allows STPNOC to withdraw a total of 2.93 x 109

 gallons (9000 ac-ft) of water over an 

approximately 3-year period. Under the terms of the permit, STPNOC may exceed 3000 ac-ft in 

an individual year; however, STPNOC cannot exceed the 9000 ac-ft limit over the period of the 

permit (approximately 3 years). STPNOC plans to use groundwater as the source for potable 

and sanitary water, concrete batch plant operation, concrete curing, cleanup activities, dust 

suppression, placement of engineered backfill, and piping hydrotests and flushing. 

Based on a monthly evaluation of water requirements during building activities and the initial 

testing of the proposed units, STPNOC estimates that development of the two proposed units 

would require groundwater during the building activities ranging from approximately 10 to 

228 gpm, and during initial testing ranging from 47 to 491 gpm (STPNOC 2010a). STPNOC 

would use groundwater up to its current permitted limit to support both the operation of the two 

existing units, and building and initial testing of the two proposed units. The applicant noted that 

short-term peak site groundwater demands in excess of the available groundwater withdrawal 

capacity would be met through water storage during building and initial testing of the proposed 

units. 

Potential offsite impact on the groundwater resource during the development of the two 

proposed STP units is bounded by an annual groundwater use of 1062 gpm (1713 ac-ft/yr). 

This is the maximum usage allowed under the groundwater use permit held by STP after 

deducting for operation of STP Units 1 and 2 (Section 2.3.2.2). A potential offsite impact is 

evaluated based on the decline in hydraulic head in the Deep Aquifer using a conservative 

analysis based on withdrawal from an onsite well pumped at a representative value 

(i.e., 500 gpm). Drawdown is evaluated at the property line and at a point 2500 ft from the STP 
 Construction Impacts at the Proposed Site 

February 2011 4-9 NUREG-1937 

production well because that is the distance allowed by the CPGCD between groundwater 

production wells unless the wells are owned by the same permit holder (CPGCD 2009). The 

well location and minimum depth to top of screen is assumed to meet CPGCD requirements of 

a minimum set back of 100 ft from the property line with a screen beginning no higher than 200 

ft below ground surface. The five existing production wells at the STP site range in depth below 

ground surface from 600 to 700 ft, and have design capacities between 200 and 500 gpm 

(STPNOC 2010a). The review team assumed that the proposed production well(s) would be 

similar to the existing production wells and have a completion depth of 700 ft below ground 

surface (BGS) and a design capacity of up to 500 gpm. 

The hydraulic head in the Deep Aquifer was between 40 and 60 ft below mean sea level (MSL) 

in the vicinity of the STP site during site characterization activities for the proposed units in 2006 

(STPNOC 2010a). Using hydraulic properties typical of the STP site (Table 2-3), the drawdown 

caused by a production well 100 ft from the site property line pumped continuously for a 5.25- 

to 7-year building period (STPNOC 2010a) at the expected rate of 500 gpm would be 

approximately 30 ft. Thus, for a single well being pumped, and adjacent wells idle, the hydraulic 

head in the vicinity of the property line would be approximately 90 ft below MSL. The top of the 

Deep Aquifer lies between 250 and 300 ft BGS, and the land surface is approximately 27 ft 

above MSL; therefore, the top of the aquifer is at the elevation 223 ft below MSL. Thus, the 

aquifer would remain confined with a confining pressure of approximately 133 ft. 

At a distance 2500 ft from the STP production well, the nearest allowed offsite well location per 

CPGCD rules for wells that are not owned by the same permit holder (CPGCD 2009), the 

drawdown would be approximately 18 ft based on the assumptions discussed above. The 

hydraulic head would be approximately 78 ft below MSL. Because of the well-spacing rules of 

the CPGCD (CPGCD 2009), the location 2500 ft from an STP production well is the assumed 

location of an adjacent offsite well, and the estimated hydraulic head is indicative of the likely 

impact to adjacent landowners. The hydraulic head of 78 ft below MSL is equivalent to a 

confining pressure on the Deep Aquifer of approximately 145 ft. 

The calculated drawdown values are shown in Table 4-1 for both the 500 gpm pumping rate of a 

single well, and the overall 1062 gpm rate available under STPNOC’s groundwater use permit. 

Use of a 500 gpm rate is consistent with current and proposed STPNOC production well 

operation. The 1062 gpm pumping rate is included to show an absolute maximum impact; 

however, it is conservative because it is an estimate of drawdown assuming a single production 

well produces all the groundwater for proposed Units 3 and 4. A further conservatism is given 

by not considering any recharge to the aquifer. Results of the 1062 gpm case conservatively 

bound an estimate of adjacent well drawdown (i.e., 37.9 ft). This is equivalent to a piezometric 

level of approximately 98 ft below MSL and a confining pressure on the Deep Aquifer of 

approximately 125 ft. 
Construction Impacts at the Proposed Site 

NUREG-1937 4-10 February 2011 

Table 4-1. Drawdown in Feet at the STP Property Line (100 ft) and a Point 2500 ft from a 

Production Well 

Pumping Rate 

(gpm) 

Distance (ft) 

100 2500 

500 29.6 17.8 

1062 62.9 37.9 

time = 7 yr building period; transmissivity = 31.379 gpd/ft 

(geometric mean); coefficient of storage = 0.00022; 

drawdown calculated using the Theis formula 

The Deep Aquifer, which would be the source of groundwater during Units 3 and 4 building 

activities, has been affected by long-term regional irrigation demand. Land surface subsidence 

since 1900 is estimated to be less than 1 ft over most of Matagorda County (LCRA 2007a), and 

in excess of 1 ft in the northwest corner of Matagorda County because of groundwater 

production associated with gas/petroleum exploration and sulfur mining (LCRA 2007a). 

STPNOC currently uses five production wells to produce groundwater in support of STP Units 1 

and 2 operations, and may install and operate one or more additional well(s) to decrease 

pumping rates at wells, distribute drawdown impacts, and ensure sufficient withdrawal capacity 

to serve the total site groundwater demand under the existing groundwater permit (STPNOC 

2010a). The existing distributed wellfield design reduces the potential for subsidence. They are 

placed and operated so that no sustained pumping occurs within 4000 ft of the existing or 

proposed units, and the CPGCD requires that wells be no closer than 2500 ft apart unless the 

wells are owned by the same permit holder. The highest rated existing wells can pump 500 

gpm, and it is assumed that new wells, if needed, would produce 500 gpm (STPNOC 2010a). 

By withdrawing the water from the existing and proposed wells, and assuming a reasonable well 

spacing between wells owned by the same permit holder, the stress on the Deep Aquifer would 

be distributed spatially across the STP site, minimizing local drawdown and the potential for 

subsidence. 

Since building and operating the proposed new units would use an estimated maximum 

1062 gpm (1713 ac-ft/yr) of Deep Aquifer groundwater, that quantity of groundwater would no 

longer move downgradient and discharge into Matagorda Bay and the Colorado River estuary 

(STPNOC 2010a). Thus, one impact of developing the proposed units is a reduction of up to 

1062 gpm (1713 ac-ft/yr) in the Deep Aquifer flow into the bay and estuarine environment. The 

reduction equates to 2.37 cfs and compares to the average minimum monthly flow of the 

Colorado River near Bay City of 327 cfs (month of August) (STPNOC 2010a), the average 

maximum monthly flow of the Colorado River near Bay City of 14,123 cfs (month of June) 

(STPNOC 2010a), and the minimum Matagorda Bay monthly target inflow of 1008 cfs for the 

month of August (STPNOC 2010a). 
 Construction Impacts at the Proposed Site 

February 2011 4-11 NUREG-1937 

As discussed in Chapter 3, STPNOC proposes to install a slurry wall to minimize the 

groundwater entering the power block excavation area from the Shallow Aquifer. STPNOC 

estimated an upper bound steady-state dewatering discharge of 6700 gpm as groundwater 

within the slurry cut-off wall is removed initially, and a steady-state of approximately 1000 gpm 

to maintain a dry excavation. The review team determined that these estimates are reasonable 

based on the relative hydraulic isolation of the excavation afforded by the slurry wall 

(STPNOC 2010b). STPNOC would install piezometers or monitoring wells inside and outside 

the slurry wall to monitor the effect of dewatering on the groundwater elevation. If STPNOC 

determines that even with the slurry wall excessive infiltration to the excavation site is occurring, 

wells would be used to pump water from within the excavation area. The water removed from 

the excavation area would be returned to the aquifer outside the slurry wall, thereby limiting any 

changes in groundwater surface elevations outside the slurry wall. Thus, the water level 

elevations in the Shallow Aquifer outside the slurry wall should experience only minimal decline, 

so the review team expects no detectable impact to nearby landowners. In addition, the 

potential conflicts over water from the Shallow Aquifer are limited because the Shallow Aquifer 

provides a lower quality groundwater than the Deep Aquifer, and as a result, wells in the 

Shallow Aquifer are generally limited to livestock watering. Groundwater for drinking water 

supplies is drawn generally from the Deep Aquifer. The removal of the dewatering product 

would occur over a relatively short period of time, and the Shallow Aquifer would recover after 

project completion. 

Because the review team determined that: the Deep Aquifer groundwater resource would be 

sufficient to sustain the projected STP site groundwater use; projected drawdown during 

building activities, and the presence of sufficient confining head would maintain the Deep 

Aquifer as a confined aquifer; production wells in the Deep Aquifer would be designed to 

minimize the potential for subsidence; there would be a relatively small decrease in discharge to 

Matagorda Bay and the estuarine environment; and because groundwater-use impacts during 

building activities would be localized and temporary, and recovery from related activity would be 

short term, the review team concludes that the groundwater-use impacts at the site and from 

construction and preconstruction activities would be temporary and SMALL and no mitigation 

would be warranted. Based on the above analysis, and because NRC-authorized construction 

activities represent only a part of the analyzed activities; the NRC staff concludes that 

groundwater-use impacts of NRC authorized construction activities would be temporary and 

SMALL and no mitigation would be warranted. 

4.2.3 Water-Quality Impacts 

Impacts to the quality of the water resources of the site are expressed for surface water (the 

Colorado River, onsite wetlands, MCR, and other surface water drainages) and groundwater 

(the shallow and deep aquifers of the Chicot Aquifer system) features that are most directly 

affected. 
Construction Impacts at the Proposed Site 

NUREG-1937 4-12 February 2011 

4.2.3.1 Surface-Water Quality Impacts 

The State of Texas prohibits the unauthorized discharge of waste into or adjacent to water in the 

State (Texas Water Code, Section 26.121). The discharge of waste may be authorized under a 

general permit (Texas Water Code, Chapter 26, Section 26.040). A general permit for 

stormwater discharges associated with building the proposed STP Units 3 and 4 was obtained 

by STPNOC’s contractor in October 2009 (STPNOC 2010a; TCEQ 2003). Under this general 

permit the State requires the development of a stormwater pollution prevention plan (SWPPP) 

that describes BMPs appropriate for the site and proposed activities. As discussed in Chapter 

3, in addition to BMPs, STPNOC would construct new retention ponds and drainage ditches to 

control delivery of sediment from disturbed areas to onsite water bodies. Sediment carried with 

stormwater from the disturbed areas would settle in the retention ponds and the stormwater 

would eventually be discharged to one or more TPDES-permitted outfalls. 

Dredging activities in the Colorado River near the RMPF and the barge slip may also result in 

disturbance of sediments and, therefore, result in a potential increase of turbidity near these 

locations as well as downstream from these locations. However, the hydrological alterations 

resulting from site development would be localized and temporary. Permits, certifications, and 

SWPPP require the implementation of BMPs to minimize impacts. Based on information 

provided by STPNOC and the review team’s independent evaluation, the review team 

concludes that the surface water quality impacts at the site and from construction and 

preconstruction activities would be temporary and SMALL and no further mitigation, other than 

BMPs discussed above, is warranted. Based on the above analysis, and because NRCauthorized construction activities represent only a part of the analyzed activities; the NRC staff 

concludes that surface water quality impacts of NRC-authorized construction activities would be 

temporary and SMALL and no mitigation other than BMPs would be warranted. 

4.2.3.2 Groundwater-Quality Impacts 

Development of proposed Units 3 and 4 should not involve intentional discharges to the aquifer 

system that underlies the STP site. Spills during building activities that might impact the quality 

of the Shallow Aquifer should be prevented and mitigated by BMPs (Texas Water Code, 

Chapter 26, Section 26.040). Except where excavation removes it, the Shallow Aquifer is 

separated from the land surface by a 10- to 30-ft thick low conductivity confining zone. 

Spills that reach the Shallow Aquifer would either be intercepted by the excavation slurry wall 

system including the dewatering system, or travel in groundwater toward the STP site property 

boundary. Groundwater flow in the Upper Shallow Aquifer away from the proposed units would 

be to the southeast and the southwest (STPNOC 2010a) toward the STP site property 

boundary. Excavation of the confining unit separating the Upper and Lower Shallow Aquifers 

provides an opportunity for spills seeping into the Upper Shallow Aquifer to also seep into the 

Lower Shallow Aquifer. The Deep Aquifer confining zone is a 100- to 150-ft-thick layer of clay 
 Construction Impacts at the Proposed Site 

February 2011 4-13 NUREG-1937 

and silt that serves to isolate the Deep Aquifer from the Shallow Aquifer. Thus, the Deep 

Aquifer is not as viable a pathway for spills that reach groundwater as the Shallow Aquifer. 

Hydraulic head data reported by the applicant (STPNOC 2010a, b) suggest plausible pathways 

and areas of discharge from the Upper and Lower Shallow aquifers. To the southeast side of 

the STP site these discharge areas include (1) the unnamed surface water tributary draining to 

Kelly Lake (7300 ft), (2) groundwater wells completed in the Shallow Aquifer (ranging from 

7300 to 9000 ft), (3) Kelly Lake (11,200 ft), and (4) the Colorado River (17,800 ft). To the 

southwest side of the STP site these discharge areas are (5) a groundwater well completed in 

the Upper Shallow aquifer (6000 ft) and (6) the Little Robbins Slough (6000 ft). STPNOC notes 

that a southwest migration pathway in the Lower Shallow Aquifer is less likely because of 

observed lower hydraulic conductivities in the aquifer to the southwest of proposed Unit 4 and 

an observed low and seasonally varying hydraulic gradient to the southwest as compared to a 

higher and continuous gradient to the southeast (STPNOC 2010b). 

Based on the hydraulic conductivity, hydraulic gradient, and effective porosity values provided 

by STPNOC and presented in Table 2-3, the following estimates of travel time from the 

proposed units to the nearest accessible environment can be made (STPNOC 2010b). In the 

Upper Shallow Aquifer the representative value of travel time to the nearest southeast exposure 

point is 154 years with a range from 57 to 400 years. The representative value of travel time in 

the Upper Shallow Aquifer for the southwest exposure point is 330 years with a range from 

117 to 821 years. The net result of a higher hydraulic conductivity and a lower hydraulic 

gradient in the Lower Shallow Aquifer are comparable if somewhat shorter travel times to the 

southeast exposure points. For the Lower Shallow Aquifer the representative value of travel 

time to the nearest southeast point of exposure is 125 years with a range from 77 to 182 years. 

These travel times allow time for cleanup and remediation to occur. Any spill within the 

excavation should be isolated from the surrounding aquifer by the slurry cut-off wall and 

dewatering pumps and, therefore, should be more readily cleaned up and remediated. 

A potential offsite impact on the quality of the groundwater resource during the building of the 

proposed Units 3 and 4 is saltwater intrusion or encroachment resulting from pumping at the 

annual average allowable rate under the existing STPNOC groundwater use permit 

(i.e., 1062 gpm/ 1713 ac-ft/yr). Production wells at the STP site are completed in the upper 

portion of the Deep Aquifer with up to 500 ft of screen, well bottom at 700 ft BGS, and pumping 

capacity of 500 gpm. The Lower Colorado River Authority (LCRA) (2007b) evaluated the design 

of wells and their production rate with regard to saltwater intrusion or encroachment 

(Section 2.3.3.2). Based on the LCRA study findings, the review team concludes the existing 

and proposed well designs at the STP site, coupled with a reasonable well spacing between 

wells owned by the same permit holder, would minimize the potential for lateral or vertical 

saltwater intrusion. 
Construction Impacts at the Proposed Site 

NUREG-1937 4-14 February 2011 

Based on the consideration of potential impact from spills and saltwater intrusion, information 

provided by STPNOC and the review team’s independent evaluation, the review team 

concludes that the groundwater-quality impacts at the site from construction and preconstruction 

activities would be temporary and SMALL and no further mitigation, other than BMPs as 

discussed above, is warranted. Based on the above analysis, and because NRC-authorized 

construction activities represent only a part of the analyzed activities; the NRC staff concludes 

that groundwater-quality impacts of NRC-authorized construction activities would be temporary 

and SMALL and no mitigation, other than BMPs discussed above, would be warranted. 

4.2.4 Water Monitoring 

Surface water, groundwater, and stormwater monitoring would take place during building 

activities for the proposed Units 3 and 4 at STP. 

During building activities for Units 3 and 4, a SWPPP would be in effect in accordance with 

TCEQ regulations (Texas Water Code, Chapter 26, Section 26.040). The SWPPP may include a 

monitoring program. As described in Section 2.3.4.1, STPNOC would also continue monitoring 

all outfalls permitted under the existing TPDES permit for STP Units 1 and 2. 

During the period prior to site disturbance, groundwater levels would be monitored at 2 wells 

completed in the Upper Shallow aquifer, and 13 well pairs which provide observations in both 

the Upper and Lower Shallow aquifers (STPNOC 2010a). During detailed design of proposed 

Units 3 and 4, current STP groundwater monitoring programs would be reviewed to identify 

necessary modifications to incorporate monitoring of the proposed units. The review would 

consider needed water level and water quality measurements for the Deep and Shallow 

aquifers, subsidence monitoring in the vicinity of proposed Units 3 and 4, and operational 

accident monitoring (STPNOC 2010b). The reviewed and modified groundwater monitoring 

programs would be used to monitor groundwater in the Deep and Shallow aquifers during the 

construction, preconstruction, and preoperational monitoring periods. Groundwater monitoring 

during construction and preconstruction would be used to track the groundwater changes during 

those activities. STPNOC committed to use BMPs including well head protection to protect the 

aquifers from impact (STPNOC 2010a). 

4.3 Ecological Impacts 

This section describes the potential impacts to ecological resources from building the proposed 

Units 3 and 4 at the STP site, including the activities associated with upgrading a 20-mi section 

of existing 345-kV transmission lines to connect the units to the grid. 
 Construction Impacts at the Proposed Site 

February 2011 4-15 NUREG-1937 

4.3.1 Terrestrial and Wetland Impacts 

This section provides information on the site-preparation activities for Units 3 and 4 at the STP 

site and the impacts on the terrestrial ecosystem. Topics discussed include terrestrial resource 

impacts at the STP site and those impacts that would be associated with replacing towers and 

upgrading two of the six 345-kV transmission lines traversing a 20-mi section of the corridor 

connecting the STP site with the Hillje Substation. 

4.3.1.1 Impacts to Terrestrial Resources – Site and Vicinity 

Building Units 3 and 4, as discussed in Chapter 3, would result in approximately 540 ac being 

disturbed on the STP site. Approximately 300 ac would be permanently altered due to 

development of new facilities and a new heavy haul road (STPNOC 2010a). 

Impacts to Habitats 

Building Units 3 and 4 would affect portions of various habitat types. The proposed power block 

area for the two new units would consist of industrial land (existing facilities, buildings and 

parking areas) and a mowed maintained field containing a large drainage ditch running eastwest through the site. The proposed project area also includes scattered small palustrine 

wetlands, scrub-shrub habitat, mixed grassland habitat where abandoned farmlands existed 

prior to the existence of STP Units 1 and 2, and maintained and disturbed fields that are 

routinely mowed (STPNOC 2010a). These open grassland/shrubland habitats are dominated 

by sea myrtle, (Baccharis halimifolia) dewberry (Rubus spp.), and bluestem (Andropogon spp.) 

grasses as described in Section 2.4.1. No forested habitat would be affected by sitepreparation or building activities. Table 4-2 provides estimates of the total number of acres that 

would be affected and identifies associated habitat types that would be permanently or 

temporarily affected (STPNOC 2010d). After the completion of the new units, the areas used 

for temporary building support would be graded, landscaped, and replanted to enhance the 

overall site appearance (STPNOC 2010a). 

Table 4-2. Estimated Acreage Affected by Proposed Activities by Habitat Type and Land Use 

Type of Habitat 

Temporary Impacts 

to Habitats 

Permanent Impacts 

to Habitats 

Existing Facilities 8.0 130.0 

Maintained and Disturbed Areas 73.6 79.4 

Mixed Grassland 19.5 

Scrub Shrub 138.9 90.6 

Wetlands 0 0 

Total Affected Acreage 240.0 300.0 

Source: STPNOC 2010d 
Construction Impacts at the Proposed Site 

NUREG-1937 4-16 February 2011 

Twenty-nine wetlands totaling approximately 17.6 ac were reviewed by Corps (Corps 2009b). 

Three of the wetlands identified on the site occur within or near the footprint (including laydown 

and spoil areas). The large man-made managed wetlands would not be expected to be affected 

by any building and development activities (STPNOC 2010a). STPNOC indicated that it would 

avoid all delineated and known wetlands and thus avoid any direct impacts to the wetland areas 

on the site (STPNOC 2010a). STPNOC has provided coordinates for wetland locations to 

project construction engineers to ensure that wetland locations are avoided and exclusion 

fences can be placed around wetland areas to minimize impacts (STPNOC 2010a). The 

applicant states that appropriate methods to stabilize areas, prevent erosion and sedimentation, 

and reduce polluted runoff would comply with applicable laws, regulations, permit requirements, 

good engineering and building practices, and recognized BMPs for all proposed activities. 

STPNOC would use silt fences and other erosion control devices, as needed, to help mitigate 

the possibility of surface water runoff from proposed activities affecting the STP site’s wetlands 

and surface water drainage features. 

Impacts to Wildlife 

Activities that would affect wildlife at the STP site include heavy equipment operation, outdoor 

lighting, and noise that may displace or destroy wildlife that inhabit the disturbance areas. Less 

mobile animals such as reptiles, amphibians, and small mammals are expected to incur greater 

mortality than more mobile animals such as birds and larger mammals. Although surrounding 

scrub-shrub, grassland, and wetland habitat would be available for displaced animals during 

building activities, movement of wildlife into surrounding areas would increase competition for 

available habitat and could result in increased predation and decreased fecundity and 

recruitment for certain species. These conditions could lead to a temporary reduction in 

population size for particular species. When building is completed, species that can adapt to 

disturbed or developed areas may readily re-colonize portions of the area where suitable habitat 

remains or is replanted or restored. 

Site preparation, development and building activities would permanently affect approximately 

300 ac on the STP site. The majority of the building and development would occur on 

maintained and industrial areas in proximity to existing infrastructure for STP Units 1 and 2. 

This change in habitat availability and extent would not be likely to increase fragmentation of 

onsite habitats available for wildlife. 

Building of the heavy haul road would disturb approximately 9 ac and travel around to the east 

of the existing ECP and then south toward the barge slip. A total of seven culverts would be 

used to span drainage areas associated with construction of the new sections of the heavy haul 

road and upgrading existing site roadways. Three of the proposed road crossings have existing 

culverts but these would be replaced in order to support the expected vehicle traffic; three 

additional culverts would be needed to span existing drainages, and one culvert would be added 

as part of preparing a new drainage area. A site assessment conducted by STPNOC in 
 Construction Impacts at the Proposed Site 

February 2011 4-17 NUREG-1937 

August 2009 documented several characteristics of the drainage areas as part of the Corps’ 

permit application. Terrestrial wildlife and fringing wetland or in-stream vegetation were 

observed in four of the six existing drainages, including alligators and mammals at one of the 

culvert sites. These drainages are “routinely maintained or disturbed (i.e., mowed)” and the 

aquatic habitat was determined to be of “low to moderate quality.” There are no proposed 

changes to the heavy haul road in the vicinity of Kelly Lake. Based on this assessment, the 

impacts to the terrestrial resources from the preparations for the heavy haul road are likely to be 

minimal, and no mitigation actions are anticipated or warranted (STPNOC 2009b). 

The existing barge slip that was built for Units 1 and 2 would be re-excavated and expanded for 

use with the proposed Units 3 and 4 (STPNOC 2009a). The excavation would involve 

approximately 1/3 ac of terrestrial habitat alongside the existing slip. Vegetation on the area to 

be excavated consists of common successional species and no unique habitats would be lost. 

Thus, the impacts on terrestrial resources of excavating and clearing required to expand the 

existing barge slip area would be minimal. 

A large number of water birds and shorebirds use the aquatic and terrestrial habitats on the STP 

site. The TPWP provides a relatively protected habitat for wintering water birds on the site. 

Because the managed wetland lies approximately 1000 ft from the proposed project site and the 

duration of the activities is limited, the long-term presence of water birds on the site should not 

be affected. Colonial water birds nesting on the dikes in the MCR are not likely to be affected 

by the building and development activities or by the increase in the water level and resulting 

loss of shoreline habitat because there is plenty of suitable habitat located elsewhere in the 

vicinity. 

Noise is another potential building and development-related activity that could affect wildlife at 

the STP site. Noise from heavy equipment power tools and building activities can affect wildlife 

by inducing physiological changes, nest or habitat abandonment, or behavioral modifications, or 

it may disrupt communications required for breeding or defense (Larkin 1996). Response to 

noise disturbance cannot be generalized across species or among genera (Larkin 1996). 

Although noise levels in building areas can be high (up to 100 decibels on the A-weighted scale 

(dBA) at 100 ft from sources of noise) and of varying duration, these high local noise levels 

would not be expected to propagate far beyond the boundaries of the site (STPNOC 2010a). At 

400 ft from the source of 100 dBA noise, noise levels would generally drop to 60–80 dBA, which 

is below the noise levels known to startle small mammals and waterfowl (Golden et al. 1980). 

However, even with this attenuation, some displacement of local small mammals and birds due 

to noise is expected during building activities. This displacement may be permanent for some 

species and temporary for others. In general, the impacts from noise are considered generally 

short-term and localized and would likely be negligible for most species. 
Construction Impacts at the Proposed Site 

NUREG-1937 4-18 February 2011 

Two mechanical draft cooling towers for the Unit 3 and 4 would be erected above the ultimate 

heat sink (UHS) basin reaching a height of approximately 119 ft above grade. Building these 

structures along with the 249-ft-tall vent stacks for the new units presents an increased potential 

for avian collision and mortality. Avian mortality from collisions with man-made structures is 

often a concern with very tall structures, and it varies relative to species-specific characteristics 

such as size, flight behavior, and habitat use, as well as weather, landscape features, and the 

size/type of equipment/structures (Brown 1993). Several studies have reported bird mortality 

also occurs from birds striking shorter structures (100 to 200 ft), but is usually related to poor 

visibility and weather conditions (Avatar 2004). STP Units 1 and 2 have not experienced any 

major bird kills (STPNOC 2010a). The additional number of bird collisions, if any, would not be 

expected to cause a noticeable reduction in local bird populations. Avian collisions during 

building of Units 3 and 4 are expected to be negligible. 

Workers commuting to the STP site arrive primarily via two-lane roads and the volume of traffic 

on these roads and particularly on road Farm-to-Market (FM) 521 would increase substantially 

(STPNOC 2010a). Increased traffic on FM 521 and feeder roads would likely increase trafficrelated wildlife morbidity and mortality. Local wildlife populations could suffer declines if road-kill 

rates were to exceed the rates of reproduction and immigration. Although road kills are an 

obvious and visible source of wildlife mortality, traffic mortality rates rarely limit population size 

except for special situations (e.g., ponds and wetlands crossed by roads where large numbers 

of migrating amphibians and reptiles would be susceptible) (Forman and Alexander 1998). 

The STP site lies within the Central Flyway migratory route for birds. Light pollution during 

facility development and building could potentially disorient flying birds and bats. Possible 

mitigation measures could include turning off unnecessary lights at night, using lights that are 

turned downward or hooded (directing light downward), and using lower-wattage lights as 

appropriate to minimize impacts on wildlife. Given the limited time period for building, long-term 

impacts of additional lighting would likely be minimal. 

4.3.1.2 Terrestrial Resources – Transmission Line Corridors 

Because no new offsite transmission corridors would be required for proposed new units, the 

discussion of potential impacts to habitats and wildlife resources in transmission corridors is 

limited to consideration of the impacts of upgrading the 20-mi STP-to-Hillje corridor. 

Impacts to Habitats in Transmission Corridors 

Potential impacts to habitats and wildlife would primarily involve those activities associated with 

building a 345-kV tie-line from STP Units 1 and 2 to the new 345-kV switchyard on the STP site 

property, and upgrading of two existing transmission lines that lead toward the Hillje Substation 

(STPNOC 2010a). American Electric Power (AEP) would take the lead role with CenterPoint 

Energy to plan the upgrades to their respective transmission lines. The Public Utility 
 Construction Impacts at the Proposed Site 

February 2011 4-19 NUREG-1937 

Commission of Texas (PUCT) regulations impose standards of construction and operation of 

transmission facilities, which state that rebuilding, upgrading, or relocation of existing electric 

transmission facilities shall comply with PUCT standards of construction and operation, and that 

in determining standard practice, PUCT shall be guided by the provisions of the American 

National Standards Institute, Incorporated, the National Electrical Safety Code (AEP et al. 

2007), and applicable codes and standards that are generally accepted by the industry, except 

as modified by PUCT. AEP and CenterPoint Energy are required to construct, install, operate, 

and maintain their respective transmission lines in accordance with the National Electrical 

Safety Code, and AEP would continue to operate and maintain its respective transmission lines 

after they are upgraded. In rebuilding or upgrading existing electric transmission facilities, AEP 

and CenterPoint Energy are directed to implement mitigation measures adapted to the specifics 

of each project in accordance with 16 Texas Administrative Code (TAC) 25.101(d). Mitigation 

may include requirements such as selective clearing of the transmission line corridor to 

minimize the disturbance to flora and fauna, implementing erosion control measures, using 

board roads to cross wetlands for tower construction, reclamation of sites with native species of 

grasses, forbs and shrubs, and returning the site to its original contours and grades (STPNOC 

2010a). 

The new onsite transmission corridor between the new switchyard for proposed Units 3 and 4 

and the existing switchyard for STP Units 1 and 2 would be approximately 600 ft wide and 

occupy approximately 12 ac (STPNOC 2010a). The connecting transmission corridor would lie 

in areas that were previously disturbed during the process of building STP Units 1 and 2. The 

new switchyard for proposed Units 3 and 4 would require grading and clearing of approximately 

12 ac of scrub-shrub habitat on the site. 

Impacts to Wildlife in Transmission Corridors 

Because no new transmission corridors would be required, the ecological impacts would 

primarily be associated with noise/movement of equipment and workers involved in changing 

out conductors and installing replacement towers along the STP-to-Hillje corridor. A variety of 

birds, small mammals, and larger mammals (white-tailed deer [Odocoileus virginianus]) could 

be disturbed by this activity (STPNOC 2010a). Impacts of these limited activities are expected 

to include temporary displacement of wildlife and potential mortality of less-mobile species such 

as reptiles, amphibians, and small mammals that are at risk of being driven over by vehicles. 

The transmission lines associated with STP are located primarily in agricultural lands and 

rangelands (STPNOC 2010a), and few animals are expected to use the corridors for activities 

other than foraging or possibly resting. Some ground-nesting birds (e.g., northern bobwhite, 

[Colinus virginianus] wild turkeys [Meleagris gallopavo] eastern meadowlark [Sturnella magna], 

horned lark [Eremophila alpestris] and killdeer [Charadrius vociferus]) in adjacent habitats could 

be affected temporarily if they are present and if the work was done during the spring/early 

summer nesting period. If work is carried out in the non-nesting periods, impacts to nesting 

birds and wildlife are expected to be negligible. 
Construction Impacts at the Proposed Site 

NUREG-1937 4-20 February 2011 

4.3.1.3 Important Terrestrial Species and Habitats 

This section describes the potential impacts to Federally listed or proposed threatened and 

endangered terrestrial species (Table 2-8) and associated designated and proposed critical 

habitat resulting from building new units on the STP site and the upgrades to the 20-mi STP-toHillje transmission corridor. Potential impacts to species listed by the State of Texas as 

threatened or endangered (Table 2-9) are also presented in this section, as well as the impacts 

of building activities on recreationally or commercially important species and important 

ecological habitats. 

The proposed location of Units 3 and 4 does not provide important habitat for any sensitive 

terrestrial species, including those Federally or State-listed as threatened or endangered, those 

proposed for listing as threatened or endangered, or candidates for listing as threatened or 

endangered. Federally listed species known to occur on the STP site include the American 

alligator (Alligator mississippiensis), which is listed as threatened. In addition, the Northern 

Aplomado falcon (Falco femoralis septentrionalis) has been observed within 10 mi of the 

STP site. 

Federally Listed Species 

American Alligator – In 1967, the American alligator was classified by U.S. Fish and Wildlife 

Service (FWS) as Federally endangered throughout its range, including Texas. By 1987, 

following several reclassification actions in other states, it was reclassified to "threatened based 

on similarity of appearance" to the Federally endangered American crocodile 

(Crocodylus acutus) in the remainder of its range (52 FR 21059). The reclassification helps 

prevent excessive take of the alligator and protects the American crocodile. Alligators use the 

wetland and aquatic features of the STP site and can be found in areas associated with large 

drainage ditches, such as the MDC and the MCR. Alligators would be expected to move away 

from building areas once activities commence and would be unlikely to stay in areas where 

heavy equipment continued operating, but similar habitat is available on the STP site. Impacts 

to alligators would likely be minimal. 

Northern Aplomado Falcon – The Northern Aplomado falcon also resides in Matagorda County 

and has been observed in nearby habitats at the Clive Runnels Mad Island Marsh Preserve, 

which is within 10 mi of the STP site. This species has been reintroduced to the Texas Gulf 

Coast over the past 15 years on Matagorda Island, which is more than 35 mi from the STP site 

(TWPD 2003). No Northern Aplomado falcons were observed during the ecological surveys 

conducted on the site; however, these birds could use the habitats on STP for foraging. 

Aplomado falcon habitat almost always contains an open grassland component with either 

scattered islands of shrubs or trees or woodland and forest borders (TPWD 2003). If falcons 

were to use the STP site as a foraging area, building activities and associated noise would likely 

cause these birds to avoid the disturbance area and use other habitats in the vicinity. Because 
 Construction Impacts at the Proposed Site 

February 2011 4-21 NUREG-1937 

these birds have not been observed on the site, adverse effects of proposed development on 

Northern Aplomado falcons are expected to be unlikely. 

No Federally listed species have been reported within 2 mi of the STP-to-Hillje transmission 

corridor (TNDD 2009). However, because the transmission corridor lies within the Central 

Migratory Flyway, individuals may fly over or through the area. 

State-Listed Species 

Six species listed as threatened by the State of Texas have been observed on or near the STP 

site and the STP-Hillje transmission corridor. The brown pelican (Pelecanus occidentalis) has 

been observed on the STP site in the vicinity of the MCR. The pelican was recently delisted as 

a Federal species of concern, but remains listed as threatened by the State of Texas. The bald 

eagle (Haliaeetus leucocephalus) is a resident on the site and nests within the STP site 

boundary. The bald eagle is State-listed as threatened and also occurs within 2 mi of the 

STP-to-Hillje corridor. The white-faced ibis (Plegadis chihi), reddish egret (Egretta rufescens), 

peregrine falcon (Falco peregrinus), and white-tailed hawk (Buteo albicaudatus) have been 

observed during the annual Christmas Bird Count (NAS 2009). Another State species of 

concern, coastal gay-feather (Liatris bracteata), is also found within 2 mi of the transmission 

corridor that would be upgraded. 

Brown Pelican – Brown pelicans were recently observed in and around the STP site and may 

use the MCR for foraging, drinking, or resting (STPNOC 2010a). On November 17, 2009, 

(74 FR 59443), the FWS delisted the brown pelican due to recovery. A review of the best 

available scientific and commercial data indicates that the species is no longer in danger of 

extinction, or likely to become so within the foreseeable future. The effective date of the rule 

was December 17, 2009. 

Brown pelicans nest on small, isolated coastal islands in Texas where they are safe from 

predators such as raccoons (Procyon lotor) and coyotes (Canis latrans). Although brown 

pelicans nest on Dressing Point Island within 20 mi of the site (TPWD 2003), the pelicans would 

not likely nest or reside in the habitats found on the STP site. No brown pelicans were observed 

in the land areas proposed for development. Noise and activities associated with building the 

additional circulating water intake structure (CWIS) on the MCR may disturb pelicans that spend 

time at the MCR and cause birds to avoid the disturbance area. However, because the MCR is 

large, these birds would be likely to move to other portions of the MCR to rest and drink. 

Similarly, noise and building activities associated with upgrades and modifications to the RMPF 

may disturb pelicans in the vicinity of the RMPF on the Colorado River. However, the pelicans 

would likely avoid the area and use other parts of the river during that time. Thus, potential 

impacts of building activities and disturbance on brown pelicans are expected to be minimal. 
Construction Impacts at the Proposed Site 

NUREG-1937 4-22 February 2011 

Bald Eagle – Based on information received from the Texas Parks and Wildlife Department 

(TPWD) and recent ecological survey data (STPNOC 2010a), an active bald eagle nest is 

located on the STP site near its eastern boundary, and a second nest site is located along the 

Colorado River near the site. Although recently delisted under the Endangered Species Act 

(ESA) (72 FR 37345), the bald eagle remains protected under the Bald and Golden Eagle 

Protection Act of 1940 (16 USC 668-668d). In 2007, new Federal management guidelines for 

bald eagles were enacted for all bald eagles in the lower 48 states that established a single 

recommended protection zone to extend out 660 ft from each eagle nest (FWS 2007). In 

addition, TPWD has established primary management zones for nest sites that extend from 

760 to 1500 ft from the nest and secondary management zones that extend 1 mi from nest sites 

where activities are restricted and avoidance of disturbance is recommended (TPWD 2009b). 

No building and development activities related to the proposed Units 3 and 4 would occur within 

1 mi of the eagle nests, and no impacts to bald eagles are anticipated.

Peregrine Falcon – Peregrine falcons are migratory through the State, and use the Texas Gulf 

coastline as a staging area during spring. During each migration, falcons assemble on the 

Texas coast, taking time to feed and rest before continuing northward. They take advantage of 

the abundant prey along the open coastline and tidal flats (TPWD 2003). Peregrine falcons 

could fly over the STP site during spring migration from Mexico and might hunt in some habitats 

onsite. However, these birds were not observed during recent ecological surveys of the 

proposed project areas, and no known nesting sites occur on the STP site. If falcons were 

found to use the STP site as a hunting area, building activities and associated noise would likely 

cause them to avoid the disturbance area and use other habitats in the vicinity. No peregrine 

falcons were noted during ecological surveys on the site, and no impacts are expected from 

building and site preparation activities on the STP site. There are no reported occurrences of 

peregrine falcons along the STP-Hillje transmission corridor; in addition, the Avian Protection 

Plan for transmission along this corridor includes protective measures to avoid potential impacts 

to avian species (STPNOC 2009b).

White-tailed Hawk – White-tailed hawks have been observed on the STP site and potentially 

use a variety of the habitats found on the STP site for hunting and resting. Recent ecological 

surveys of the proposed project areas did not observe any white-tailed hawks and did not detect 

any nest sites. However, white-tailed hawks typically nest in shrubs and short trees (Kuvlesky 

and Kane 2008), and could use portions of the scrub-shrub habitat outside the disturbed area 

for nesting. Building activities and associated noise would likely cause these birds to avoid the 

disturbance area and use other habitats in the vicinity. Impacts to white-tailed hawks are 

expected to be negligible. 

Wading Birds – The white-faced ibis and the reddish egret are both wading birds that frequent 

marshes and ponds and potentially could use the managed prairie wetland habitat or possibly 

other open water and emergent wetlands found on the STP site. Proposed project activities are 
 Construction Impacts at the Proposed Site 

February 2011 4-23 NUREG-1937 

relatively distant (~200 yd) from the Texas Prairie Wetlands but could affect the use of the 

wetlands for foraging and resting by waterbirds during the period of development. However, the 

managed wetland is distant enough that noise levels should be less than levels that would 

cause birds to startle (60-80 dBA) (STPNOC 2010a). Building and development activities would 

avoid wetlands on the site. Therefore, impacts to wading birds and other waterbirds are 

expected to be minimal. 

State-Listed Species Not Observed at STP – Seven additional wildlife species listed as 

threatened in Texas and two plant species that are considered species of concern by the State 

have the potential to occur on the STP site and the STP-to-Hillje transmission corridor. 

However, surveys of proposed project areas did not find evidence of these species 

(ENSR 2007a). 

Wood storks (Mycteria americana) historically were observed in the emergent wetlands and 

bottomland forest wetlands on the STP site (NRC 1975), but would not be likely to use the 

shrub-scrub and grassland habitats that exist within the disturbance footprint. No wood storks 

have been observed during the Christmas Bird Count surveys of the site. The sooty tern 

(Sterna fuscata) is primarily a pelagic bird and in eastern North America nests on islands in the 

Gulf of Mexico from Texas to Louisiana (TPWD 2005; NatureServe Explorer 2009). This 

species is not likely to use or occur in the habitats found on the STP site. 

Reptile species that potentially could occur on the STP site include the Texas scarlet snake 

(Cemophora coccinea linerii), the Texas tortoise (Gopherus berlandieri), the smooth green 

snake (Liochlorophis vernalis), and the timber rattlesnake (Crotalus horridus). Although these 

species were not noted during any of the ecological surveys on the site, they potentially could 

use the scrub-shrub and grassland habitats. The Texas horned lizard (Phrynosoma cornutum) 

is less likely to be found on the STP site because it prefers more arid areas with sparse 

vegetation. 

Coastal gay-feather and threeflower snakeweed (Thurovia triflora) are forbs that are endemic to 

the coastal prairie grasslands and coastal gay-feather occurs within 10 mi of the STP site. 

These species are not likely to occur in the successional vegetation and habitats found in 

proposed project areas on the site. Previous use of the site for agriculture and rangeland before 

construction of STP Units 1 and 2 has significantly altered the vegetation community 

(STPNOC 2010a). 

Ecologically Important Terrestrial Habitats and Species 

Because the proposed project area consists primarily of existing facilities and successional 

vegetation and habitats, it does not provide any special or unique habitats or plant communities. 
Construction Impacts at the Proposed Site 

NUREG-1937 4-24 February 2011 

None of the proposed project area is designated as critical habitat by the FWS, and areas 

designated as critical habitat are not found on the STP site or along the associated transmission 

line corridors. 

A number of palustrine emergent and palustrine scrub-shrub wetlands occur on the STP site 

including the Texas Prairie Managed Wetlands. Potential impacts of proposed building and 

development to wetland habitats are described in Section 4.3.1.1. 

The STP-to-Hillje transmission line corridor travels across lands that are primarily used for 

agriculture or grazing livestock. Because of the associated land use, no known unique plant 

communities or habitats occur in the corridor. Wetland habitats do occur in the corridor but are 

unlikely to be permanently affected by any of the proposed building activities associated with 

upgrading and replacing existing towers. Access to lines and towers might cause temporary 

impacts to wetlands (STPNOC 2010a). Potential impacts to the wetland habitats in this 

transmission corridor are expected to be negligible. Therefore, impacts to ecologically valuable 

habitat and species would be minimal. 

Commercially and Recreationally Valuable Species 

Species defined as “important” in NUREG-1555 (NRC 2000) because they are commercially or 

recreationally valuable exist within the proposed site disturbance footprint and include game 

species such as white-tailed deer, gray and fox squirrels (Sciurus spp.), mourning doves 

(Zenaida macroura), and northern bobwhites. However, the area within the disturbance 

footprint does not provide high quality or unique habitat for these game species. Also, the 

proposed project area's value as wildlife habitat is affected by its proximity to STP Units 1 and 2 

and infrastructure, with higher levels of associated human activity and noise. The surrounding 

area has ample habitat for these species such that it would be able to accommodate animals 

displaced as a result of proposed land-clearing and building activities. Therefore, impacts to 

commercially and recreationally valuable species would be minimal. 

4.3.1.4 Terrestrial Monitoring 

No monitoring of terrestrial resources is planned during the building activities onsite or in the 

transmission corridor. Regulatory agencies have not required ecological monitoring of the STP 

site or its associated transmission line corridors since the period of reservoir filling (mid 1980s), 

and there is no ongoing monitoring. The addition of proposed Units 3 and 4 would not require 

any significant changes to the current practices for maintenance of the corridors, including 

vegetation management for the transmission line system. 
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February 2011 4-25 NUREG-1937 

4.3.1.5 Summary of Impacts to Terrestrial Resources 

In summary, site preparation and building activities for proposed Units 3 and 4 would result in 

the permanent loss of approximately 300 ac, and the temporary additional disturbance of 

approximately 240 ac. Areas temporarily affected by site preparation and building activities 

would be revegetated. Areas permanently lost to new facilities include significant acreage of 

maintained areas associated with existing facilities. Building Units 3 and 4, and the upgrades to 

the 20-mi section of the 345-kV transmission lines would be done according to Federal and 

State regulations, permit conditions, existing procedures, and BMPs, such as minimizing 

removal of existing vegetative cover, maintenance of existing drainage patterns, prohibitions of 

restrictions of equipment and vehicles around and through water bodies, and restrictions on fill 

activities. Wetlands in the disturbance footprint would be avoided, and no permanent losses of 

wetlands are expected (STPNOC 2010a). STPNOC is required to comply with conditions of the 

404 permit from the Corps including any required mitigation. BMPs would be applied to prevent 

sedimentation, runoff, and erosion that could affect wetland habitats. Based on quality of the 

habitat lost and the proximity of the proposed building and development activities to existing 

facilities and infrastructure, the staff concludes potential impacts to upland and wetland wildlife 

habitats on the STP site and associated transmission corridors would be negligible. 

The staff has determined that the related impacts of habitat loss, noise, collisions with elevated 

structures, increased light pollution, and increased traffic may adversely affect onsite wildlife. 

However, these impacts would be temporary, minor, and mitigable. The destruction, temporary 

displacement and reduced productivity, and re-colonization of wildlife also apply to offsite 

disturbances that would result as the transmission line towers would be replaced and upgraded. 

The potential impacts associated with these disturbances would also be temporary, minor, and 

mitigable. 

No Federally or State-listed threatened or endangered species, critical habitat, or suitable 

habitats associated with potentially identified species were observed during pedestrian surveys 

of the proposed disturbance area (STPNOC 2010a; ENSR 2007a). One Federally listed 

species (American alligator) has been observed within the STP site in wetland and aquatic 

habitats (Section 2.4.1). Five species listed as threatened by the State of Texas have been 

observed recently on the STP site: the bald eagle, white-faced ibis, reddish egret, peregrine 

falcon, and white-tailed hawk. The brown pelican, State-listed as endangered, has been 

observed near and on the MCR and the Colorado River. None of the Federally listed species 

would be expected to occupy or make any significant use of the habitats within the disturbance 

footprint for the proposed units. The six State-listed species also would not be expected to 

occupy or make significant use of habitats in these areas. 

Based on the review team’s independent evaluation of the threatened and endangered species 

surveys, historical records, life history information, known threatened and endangered species 

locations, and information provided by STPNOC in its ER (STPNOC 2010a), the review team 
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NUREG-1937 4-26 February 2011 

concludes the impacts on terrestrial Federally and State-listed threatened and endangered 

species from building activities on the STP site would negligible, and further mitigation would not 

be warranted. 

TPWD (TPWD 2010), in its comments on the draft EIS, recommended that “STPNOC formulate 

a compensatory mitigation plan for all impacts to fish and wildlife habitat, including wetlands and 

shallow water habitat for the proposed project. This would include impacts to species and 

habitats covered under federal law and state resource habitat types not covered by state or 

federal law. At a minimum, TPWD recommends a replacement ratio of 1:1 for state resource 

habitat types.” Because the applicant plans to restore areas temporarily disturbed by 

construction activities through grading, landscaping, and replanting of these areas, TPWD 

recommended that “all temporary construction impacts be restored to preconstruction contours 

and conditions and that STPNOC prepare a restoration plan and provide this plan to TPWD for 

review and comment” (TPWD 2010). The NRC does not have the statutory authority to require 

the applicant to submit a compensation or restoration plan to a state agency for its review. As 

described below, the impacts of construction and preconstruction to terrestrial and wetland 

ecological resources would be SMALL. The review team did not rely upon the implementation 

of TPWD’s recommendations in reaching the impact determination. 

Based on information provided by STPNOC and the review team’s independent evaluation, the 

review team concludes that the impacts of preconstruction and construction activities to 

terrestrial and wetland ecological resources, including threatened and endangered species, on 

the site would be SMALL, and no additional mitigation measures are proposed at this time. 

However, the Corps may require mitigation as a stipulation for issuing the required Corps 

permit. The LWA rule (72 FR 57426) specifically states that transmission lines and heavy haul 

roads are not included in the definition of construction. Based on these analyses, and because 

the NRC-authorized construction activities represent only a portion of the analyzed activities, the 

NRC staff concludes that the impacts of NRC-authorized construction activities would be 

SMALL, and no mitigation measures have been identified at this time. 

4.3.2 Aquatic Impacts 

Impacts on the aquatic ecosystem from building the proposed Units 3 and 4 at STP would 

mainly be associated with onsite water bodies, the Colorado River, and upgrading a 20-mi 

section of existing 345-kV Hillje transmission lines. Onsite water bodies include the MDC, the 

Little Robbins Slough, the MCR, and wetlands. Impacts to the Colorado River would include 

improvements to the existing RMPF, and the barge slip – all systems that were built for existing 

STP Units 1 and 2. No new transmission corridors are required for proposed Units 3 and 4. 
 Construction Impacts at the Proposed Site 

February 2011 4-27 NUREG-1937 

4.3.2.1 Aquatic Resources – Site and Vicinity 

Sloughs, Drainage Areas, Wetlands, and Kelly Lake 

Site preparation and development activities for the proposed Units 3 and 4 that would potentially 

affect the onsite water bodies include the relocation and removal of drainage areas, building of 

culverts for a heavy haul road from the barge slip to the proposed power blocks, and 

management of groundwater and stormwater during the site preparation and development 

activities. STPNOC has indicated that they would avoid all delineated and known wetlands 

during these activities (STPNOC 2010a). Relocation of the MDC would eliminate those aquatic 

organisms currently in the drainage (ER Figure 2.3-6) (STPNOC 2010a). In 2007, several 

species were surveyed in the MDC (ENSR 2007b), and were discussed in Section 2.4.2.1. 

These species (e.g., mosquitofish [Gambusia affinis], various sunfish species) likely moved into 

the MDC from Little Robbins Slough. Upon relocation of the MDC, these species are likely to 

recolonize the channel when the flows are reconnected to the slough. Overall, given the 

stability of regional populations and the likelihood of recolonization, affects on regional aquatic 

communities would be minimal as a result of activities on or near onsite water bodies. 

A total of seven culverts would be used to span waters associated with the new portions of the 

heavy haul road and upgrades to existing site roadways. Three of the proposed road crossings 

have existing culverts but these would be replaced in order to support the expected vehicle 

traffic. Three other culverts would be needed to span existing drainages. One culvert would be 

added as part of preparing a new drainage area. A site assessment of the drainage areas 

conducted by STPNOC in August 2009 in support of the Corps’ permit application documented 

several characteristics including waterbody type, stream flow, flow type, bank slope, stream 

depth and width, water appearance, substrate, width of riparian zone, channel condition and 

observed disturbances, and aquatic habitats. Aquatic organisms were observed in four of the 

six existing drainages, including in-stream vegetation, aquatic insects, clams, and fish. These 

drainages are “routinely maintained or disturbed (i.e., mowed)” and the aquatic habitat was 

determined to be of “low to moderate quality.” There are no proposed changes to the heavy 

haul road in the vicinity of Kelly Lake. Based on this assessment, the impacts to the aquatic 

resources from the preparations for the heavy haul road are likely to be minimal and no 

mitigation actions are anticipated or warranted (STPNOC 2009b). In response to comments 

received during the public notice comment period for the Corps permit and the comment period 

for the DEIS, STPNOC has proposed to compensate for unavoidable impacts to relatively 

permanent waters resulting from the construction of the heavy haul road by purchasing stream 

credits from the Mill Creek Mitigation Bank (STPNOC 2010e). 

Preparation of the foundation for the proposed power blocks would require dewatering activities 

because the depth of the foundation is below the groundwater level, as well as collection of rain 

water that enters the excavated areas. The removal rate of groundwater from the region of the 

power block foundations would change with time; the estimates initially are to be 6700 gpm and 
Construction Impacts at the Proposed Site 

NUREG-1937 4-28 February 2011 

then declining to approximately 1000 gpm (due to the surrounding slurry wall slowing the rate of 

groundwater intrusion). The groundwater and stormwater would be collected and discharged 

into the MCR (STPNOC 2009b). Such disposal would have little impact on aquatic resources in 

the MCR because turbidity would be low, water temperature would be similar to ambient 

temperatures, and any chemical spills would require treatment according to the SWPPP and 

spill prevention plan prior to disposal. 

Impacts to aquatic ecology from onsite preparation activities are most likely to be associated 

with management of erosion and sedimentation associated with stormwater. Temporary and 

permanent erosion and sediment control measures would be needed to minimize the flow of 

disturbed soils into the ditches and wetlands. These measures would be described in the 

SWPPP that would be submitted and approved by TCEQ as part of the TPDES general permit 

relating to stormwater discharges for building activities (TCEQ 2008). Check dams, rip-rap, 

retention basins, and sediment barriers may be part of the systems established to collect 

stormwater drainage to allow sediment and other debris to be captured before it passes into 

protected waters. Temporary measures would include minimal clearing and maintenance of 

existing vegetative cover, silt fencing, mulching, and erosion control blankets. Permanent 

measures would include reestablishing natural drainage patterns, vegetated swales, and 

permanent seeding/plantings (STPNOC 2010a, 2008a). 

Main Cooling Reservoir 

A new CWIS as well as a new discharge structure for proposed Units 3 and 4 would be added 

to the MCR. A permanent sheet pile cofferdam would be installed on the west side of the north 

separation dike for the intake and pumphouse. A temporary cofferdam would be erected on the 

interior of the MCR embankment for the installation of the discharge structure, located next to 

the existing discharge structure for STP Units 1 and 2. The cofferdams, once in place, would 

help reduce erosion and sedimentation around the disturbance areas and minimize impacts to 

the aquatic community in the MCR (STPNOC 2010a). The noise generated during installation 

of the cofferdam and new structures would disturb the aquatic organisms in the vicinity of the 

structures but the region of disturbance would likely be small because the noise would likely be 

attenuated quickly considering the depth and size of the MCR. Therefore, impacts to aquatic 

species and habitat in the MCR are expected to be minimal. 

Colorado River 

Preparations along the Colorado River for facilities associated with the proposed new units 

would be limited to the RMPF, the barge slip and barging traffic to the STP site (STPNOC 

2010a, 2009d). The intake screens on the RMPF would be removed from the water and either 

refurbished or replaced, and would involve little underwater disturbances that would be localized 

to the front of the intake structure. New pumps for proposed Units 3 and 4 would be installed 

behind the intake structure and would not result in any disturbances within the river. To 
 Construction Impacts at the Proposed Site 

February 2011 4-29 NUREG-1937 

maintain proper support of the discharge structure for all four units (the two existing and two 

proposed), STPNOC plans on restoring the revetment along 1600 ft of shoreline on the west 

bank of the Colorado River, beginning at the MCR spillway and extending down the river to the 

STP site property line. They have requested approval from the Corps to conduct the restoration 

work as part of the existing permit with the Corps or under the Nationwide Permit No. 13 for 

bank stabilization activities. There are no other plans for changing the spillway at the MCR or 

the discharge structure along the river for the proposed new units (STPNOC 2010a). 

The existing barge slip that was built for Units 1 and 2 would be re-excavated and expanded for 

use with the proposed Units 3 and 4 (STPNOC 2009b). Dredging around the existing barge 

terminal is anticipated and would be conducted in accordance with the necessary dredging 

permits (STPNOC 2008a). Material to be dredged is predominantly silty-clay soils with 

approximately 6 in. of “detritus and silt soils” on the surface. Dredged material would be placed 

in the designated onsite location that is currently used for storage of material removed during 

maintenance activities with the RMPF (STPNOC 2009b). When the barge slip for Units 1 and 2 

was built, a sheet pile wall was installed in the river to control sedimentation and limit 

downstream increases in turbidity and siltation (STPNOC 2010a). At that time, an estimated 

area of less than one ac of benthic habitat was destroyed during the building of the barge slip 

(STPNOC 2010a). The areal extent and types of disturbances to the shoreline and in the river 

for the re-excavation and expansion of the slip for transporting the barged materials for 

Units 3 and 4 is anticipated to be similar to or less than the disturbances during the building of 

Units 1 and 2 (STPNOC 2009b). The aquatic resources around the barge slip would likely 

recolonize after removal of the sheet pile wall and barging activities are completed. 

Delivery of major equipment for Units 3 and 4 would be by barging the material to the site, and 

the barges could interact with aquatic organisms (e.g., sea turtles) along the route to STP. The 

cargo that would be barged to the site includes prefabricated modules, large components 

fabricated overseas, and bulk commodities. STPNOC has stated that no firm shipping contracts 

have been developed for transportation of the materials to the STP site. However, STPNOC 

has indicated that the current plans call for prefabricated modules and components fabricated 

overseas to be shipped to the Port of Freeport (or points north) where they would be transferred 

from ocean-going ships to inland barges. The inland barges would then enter the Gulf 

Intracoastal Waterway (GIWW) and move south to the confluence of the Colorado River and 

proceed upstream to the site. The ports in Matagorda Bay to the south of the site currently do 

not have adequate facilities for the transfer of heavy cargo from ocean-going vessels to inland 

barges. Therefore, transport of these materials would not involve the Matagorda Ship Channel 

or the diversion canal in Matagorda Bay (STPNOC 2009b). 

STPNOC plans to ship bulk commodities (e.g., aggregate or structural fill materials) via inland 

barge. Access to the Colorado River by the barges would depend on the source of the 

materials, and could be transported either from the north or south along the GIWW. However, 
Construction Impacts at the Proposed Site 

NUREG-1937 4-30 February 2011 

no bulk commodity traffic is expected to traverse the diversion canal in Matagorda Bay or the 

Matagorda Ship Channel (STPNOC 2009b). 

Activities in the Colorado River are likely to be short in duration, and due to erosion and 

sedimentation controls, the activities are not likely to release significant quantities of sediment or 

silt. Increase in turbidity is not likely to be transported far down the river. Thus, impacts from 

building the proposed Units 3 and 4 at STP are likely to be negligible for aquatic resources in 

GIWW and Matagorda Bay. 

4.3.2.2 Aquatic Resources –Transmission Line Corridors 

No new offsite transmission corridors would be required for proposed Units 3 and 4. Potential 

impacts to aquatic ecological resources in transmission corridors are limited to consideration of 

the impacts from site preparation activities and placement of the new 345-kV switchyard for 

Units 3 and 4, 345-kV tie-line from Units 1 and 2 to the new 345-kV switchyard, and from 

upgrading the 20-mi STP-to-Hillje corridor. 

The onsite addition of a new switchyard for proposed Units 3 and 4 and tie-line to existing Units 

1 and 2 are proposed for areas that have previously been disturbed (Figure 3-1). The new 

switchyard would be placed on the north side of the relocated MDC, and the lines would span 

across the MDC. There are wetlands in the vicinity of the tie-line from Units 1 and 2 to the new 

switchyard. The building plans indicate that all ditches and wetlands would be avoided by 

building activities (STPNOC 2010a). Impacts to aquatic resources in onsite wetlands and 

ditches would be minimized by temporary and permanent measures for erosion and sediment 

control as required under TCEQ’s SWPPP (TCEQ 2008). Such measures include: minimizing 

removal of existing vegetative cover, maintenance of existing drainage patterns, prohibitions or 

restrictions of equipment and vehicles around and through water bodies, use of silt curtains and 

other sediment transport barriers, and restrictions on fill activities. Upon completion of activities, 

areas affected would be restored (STPNOC 2010a). 

Offsite, there would be some modification or replacement of towers on the transmission line 

from the STP site to the Hillje Substation (STPNOC 2010a). Activities would primarily be 

associated with existing pads for the towers, and vehicles would access the pads using existing 

roads. Access to lines and towers might require temporary impacts to wetlands resulting from 

the placement of board roads for use with heavy equipment. Erosion of soils and stormwater 

drainage are likely to be the only impacts to aquatic resources along the STP-to-Hillje 

transmission corridor (STPNOC 2010a). Affects from sedimentation would be limited by 

temporary and permanent measures for erosion and sediment control as required under 

TCEQ’s SWPPP (TCEQ 2008; STPNOC 2010a). 
 Construction Impacts at the Proposed Site 

February 2011 4-31 NUREG-1937 

4.3.2.3 Important Aquatic Species and Habitats 

This section describes the potential impacts to important aquatic species and habitats from 

building proposed Units 3 and 4 at the STP site, and the upgrades for the STP-to-Hillje 

transmission corridor. The general life histories of these species are presented in Section 2.4.2. 

Important Species 

Potential impacts on species listed in Table 2-14 from construction and preconstruction activities 

in the vicinity of the site and associated transmission lines are discussed categorically in this 

subsection. 

Commercial and Recreational Species

Activities associated with building the proposed Units 3 and 4 facilities are primarily onsite and 

along the Colorado River at the STP site. Barging of materials (e.g., large equipment and bulk 

commodities) to the STP site would involve traffic in the waterways beyond the Colorado River, 

from Matagorda Bay and Port Freeport, and in the GIWW. Commercially and recreationally 

important species that are found onsite (e.g., black drum [Pogonias cromis] and blue crab 

[Callinectes sapidus]) are in water bodies that are not open to the public (e.g., in the MCR) and 

have limited ability to contribute to the populations found offsite. Impacts to those species 

would primarily be associated with erosion and sedimentation control. Stormwater and 

groundwater removed during preparation of the foundations for the proposed power blocks 

would be managed according to the SWPPP and discharged into the MCR. The aquatic 

resources in the MCR would experience negligible impacts from this disposal since the quality 

of the discharged water would be similar to that in the MCR (STPNOC 2009b). 

Activities associated with the barge slip would temporarily affect commercially and recreationally 

important species in the Colorado River. Re-excavation and expansion of the existing barging 

slip would affect approximately one ac of aquatic habitat in the Colorado River. Commercial 

and recreational species in the river could be displaced from the affected shoreline while the 

sheet pile wall is put in place and during excavation activities. Sediment would be dislodged 

and turbidity in the vicinity of the sheet pile wall would increase for a short period of time. Barge 

traffic delivering material to the site would create cavitations that might cause fish avoidance 

temporarily in the vicinity of the barge slip. 

The improvements planned for the RMPF, dredging at the barge slip, and barge traffic would 

have limited impacts on commercially and recreationally important species. Commercially and 

recreationally important species in the Colorado River were discussed in Section 2.4.2.3. These 

activities would be short in duration, impacts from increased turbidity and siltation would be 

limited by control measures, and damaged or affected benthic habitat would be small (likely less 

than 1 ac) and benthic species would recolonize after activities at the barge slip are completed. 
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NUREG-1937 4-32 February 2011 

Most commercially and recreationally important species in the vicinity of these activities would 

likely avoid the area during these activities. 

Invasive Species

Taxa such as giant salvinia (Salvinia molesta) and Hydrilla were not reported in the onsite water 

bodies. However, corbicula was collected from the MCR in 1981, and is known to occur in the 

Colorado River (STPNOC 2010a). Disturbances to onsite water bodies could encourage 

invasive species to proliferate by allowing them to establish in the new habitats created by 

opening up drainage areas before the indigenous species can recolonize the area. Since these 

organisms have not been noted in the existing onsite water bodies, there does not seem to be a 

mechanism for the introduction of invasive species to the disturbed areas. The amount of area 

in the Colorado River that is being disturbed is minimal and probably not enough area to allow 

the invasive species a great advantage. 

Ecologically Important Species

Primarily ecologically important species are benthic aquatic invertebrates or fish that are 

foraged by other species of concern. Site preparation and development activities can suspend 

sediments in water bodies that are likely to affect benthic invertebrates and fish. Dredging can 

remove benthic organisms. As discussed above, impacts from sedimentation would be 

controlled using a variety of measures (e.g., stormwater management for onsite activities and 

sheet pile walls in the MCR and Colorado River). Impacts from erosion and sedimentation 

would likely be temporary and minimal. Benthic organisms that are lost during dredging 

activities would likely recolonize the affected areas with time. The presence of abundant forage 

fish within the Lower Colorado River is summarized in Table 2-14. Activities associated with 

refurbishing the intake structure and re-excavating the barge slip may affect the presence or 

habitat utilization of these forage species in the vicinity of these activities. However, these 

impacts are expected to be temporary as fish should return to these areas within the Colorado 

River following completion of site preparation and development activities. 

Species with Designated Essential Fish Habitat

The Lower Colorado River, GIWW, and Matagorda Bay are considered essential fish habitat 

(EFH) within Ecoregion 5 of the Gulf of Mexico, as designated by the Gulf of Mexico Fishery 

Management Council in accordance with the Magnuson-Stevens Fishery Conservation and 

Management Act (MSA) (16 USC 1801 et seq.). No habitats of particular concern occur in 

either water body or in associated nearshore areas (GMFMC 2004). Section 2.4.2.3 and the 

EFH assessment in Appendix F discuss the species and life stages with designated EFH in the 

vicinity of the STP site and associated transmission corridors. 
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February 2011 4-33 NUREG-1937 

Spanish and king mackerel (Scomberomorus maculatus and S. cavalla, respectively) have not 

been collected in the Colorado River in 1983-1984 or 2007-2008 (ENSR 2008a). The river 

would be potential foraging habitat for the mackerel. Improvements at the RMPF would not 

likely affect the mackerels. During dredging at the barge slip, the mackerels might avoid the 

area due to changes in turbidity from sedimentation or during erection and dismantlement of any 

sedimentation control systems in the river (e.g., sheet pile walls). 

Gray (mangrove) snapper (Lutjanus griseus) were collected within the first 3 mi of the river and 

the GIWW in 2007-2008 (ENSR 2008a). Juvenile gray snapper are likely to be the most 

common in the Colorado River. However, the habitat in the river does not include regions of 

sea grass or other areas for protection. Organisms would most likely avoid the area during 

activities in the river. The benthic habitat disturbed by dredging would likely recover and 

support benthic invertebrates that are a food source for the gray snapper. 

Red drum (Sciaenops ocellatus) have been collected in the MCR and all along the Colorado 

River in 2007-2008 (ENSR 2008a, b). This is one of the species that has not been collected 

during past surveys of the Colorado River but are known to be in Matagorda Bay and the 

GIWW. Red drum were collected with all types of sampling gear, indicating that the species 

was well distributed in the river. Presence of the species in the MCR indicates that larvae or 

juveniles were entrained at the RMPF. During activities in the Colorado River, the red drum 

juveniles and adults would most likely avoid the area. The benthic habitat disturbed by dredging 

would likely recover and support benthic invertebrates that are a food source for the red drum. 

Brown, pink, and white shrimp (Farfantepenaeus aztecus, F. duorarum, and Litopenaeus 

setiferus, respectively) have been collected in the MCR and all along the Colorado River in 

1983-1984 and 2007-2008 (ENSR 2008a, b; NRC 1986). White and brown shrimp were more 

abundant at the confluence of the river and the GIWW than farther up the river. These shrimp 

species are an important commercial resource in Matagorda Bay. Improvements at the RMPF 

are not likely to affect the shrimp. Dredging at the barge slip would temporarily remove habitat 

for the shrimp and their food source. 

Gulf stone crabs (Menippe adina) have not been collected in the Colorado River in 1983-1984 

or 2007-2008 (ENSR 2008a). While all lifestages of this species of stone crab are listed as 

occurring in the Colorado River to just beyond the FM 521 bridge; the habitat, salinity, and 

temperature of the river is not likely to support many of the organisms, and they are most likely 

to be found in Matagorda Bay. Improvements at the RMPF are not likely to affect stone crab. 

Dredging at the barge slip would temporarily remove habitat for the stone crab and their food 

source. 
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NUREG-1937 4-34 February 2011 

Federally and State-listed Species

Section 2.4.2.3 discusses the 12 species Federally listed as protected by the FWS and NMFS 

under the ESA in Matagorda County and the coastline of Texas. Of these species, only the 

threatened Atlantic green turtle (Chelonia mydas), the endangered hawksbill turtle 

(Eretmochelys imbricata), and the endangered Kemp’s ridley turtle (Lepidochelys kempii) are 

likely to be in the vicinity of the routes for barging material and equipment to the STP site. Sea 

turtles can be affected by barging traffic. The speed of the barges is low enough that turtles that 

come in contact with the barges or are entrained in the cavitations created by the moving 

barges would not be severely damaged (National Research Council 1990). There have been no 

reports of stranded turtles due to barges in Matagorda Bay or the GIWW between Matagorda 

Bay and Port Freeport. More detailed information in support of a joint consultation with the FWS 

can be found in the biological assessment in Appendix F. 

The State-listed species in Matagorda County include three threatened species (blue sucker 

[Cycleptus elongates], smooth pimpleback [Quadrula houstonensis], and Texas fawnsfoot 

[Truncilla macrodon]) as well as four rare and protected species (American eel [Anguilla 

rostrata], Gulf Coast clubtail [Gomphus modestus], creeper [Strophitus undulates], and pistolgrip 

[Tritogonia verrucosa]). The blue sucker would be located in the Colorado River and not likely 

be in the onsite water bodies. This species was not collected during the aquatic surveys of the 

river in the 1970s, 1980s, and 2007-2008. Blue suckers move upstream in the spring to areas 

with riffles for spawning. Since spawning habitat is not within the vicinity of the STP site, 

activities in the Colorado River associated with the RMPF, shoreline restoration, and 

maintenance dredging for the proposed Units 3 and 4 would not likely affect eggs and larvae of 

the species. Juvenile and adult blue suckers forage in the deeper channels of the river and are 

strong enough swimmers to avoid activities in the river (TPWD 2009a). 

The two State-listed threatened freshwater mussels in Matagorda County are likely to be found 

in different water bodies at STP. The smooth pimpleback could be found in the MCR and the 

Colorado River in the vicinity of STP since the species prefers small to moderate rivers as well 

as reservoirs, tolerates the flow regimes of the MCR and river, and prefers the type of substrate 

found in the MCR and river. However, since the species does not tolerate dramatic water level 

fluctuations, it is not likely to be found in the other onsite water bodies. The smooth pimpleback 

has not been reported in the surveys of aquatic organisms at the STP site (NRC 1975, 1986; 

ENSR 2007a, b, 2008a, b). There is no information on the reproduction of the smooth 

pimpleback (e.g., glochidia are unreported) (Howells et al. 1996; TPWD 2009a). Activities in the 

Colorado River could remove adult mussels if the substrate is removed. If habitat for the 

smooth pimpleback is found in the area, TPWD might require mitigation activities (e.g., mussels 

could be collected and relocated). 

Texas fawnsfoot has not been reported in the surveys of aquatic organisms at STP (NRC 1975, 

1986; ENSR 2007a, b, 2008a, b). What little is known about the species is that it has been 
 Construction Impacts at the Proposed Site 

February 2011 4-35 NUREG-1937 

found in river systems similar to the Colorado River and in flowing rice irrigation canals, but the 

Texas fawnsfoot has not been found in impoundments. Thus, Little Robbins Slough and the 

Colorado River might be suitable habitat for the species. In addition, the ponds and drainage 

areas that are located along the transmission corridor could be appropriate habitat for the Texas 

fawnsfoot. There is no information on the reproduction of the Texas fawnsfoot (e.g., glochidia 

are unreported) (Howells et al. 1996; TPWD 2009a). If habitat for the Texas fawnsfoot is found 

in the area, TPWD might require mitigation activities (e.g., mussels could be collected and 

relocated). 

The American eel is a State-listed protected species that was collected in the MCR during the 

impingement sampling for the CWIS for Units 1 and 2 (ENSR 2008b). The American eel was 

not collected in the Colorado River, but has been collected in Matagorda Bay (STPNOC 2010a). 

The adult eel collected in the MCR most likely was entrained as a larvae moving up the 

Colorado River from the Gulf and the Bay. Activities in the Colorado River associated with the 

RMPF, shoreline restoration, and maintenance dredging for the proposed Units 3 and 4 would 

not likely affect juvenile or adult life stages of the species because they are motile and can avoid 

the area. However, larvae could be lost during dredging activities since they are not strong 

enough swimmers to avoid activities in the river. 

Gulf Coast clubtail, a dragonfly, is a State-listed protected species in Matagorda County. Little 

Robbins Slough and Colorado River could have the appropriate habitat for the early life stages 

of the clubtail (TPWD 2009a), but were not reported in any surveys of onsite water bodies and 

the river (NRC 1975, 1986; ENSR 2007a, 2008a, b). Habitat could be lost from onsite activities 

but the SWPPP could minimize impacts to the early life stages of the clubtail by managing water 

flow in basins and minimizing turbidity that could change their habitat. Clubtails in the Colorado 

River could be lost or their habitat removed by activities associated with the RMPF, shoreline 

restoration, and maintenance dredging for the proposed Units 3 and 4. If habitat for the Gulf 

Coast clubtail is found in the area, TPWD might require mitigation activities. 

The protected State-listed creeper and pistolgrip are known to be in the Colorado River 

drainage, and the onsite water bodies and Colorado River could have the appropriate habitat for 

these freshwater mussels (TPWD 2009a). However, these species were not reported in any 

surveys of onsite water bodies and the river (NRC 1975, 1986; ENSR 2007a, 2008a, b). Habitat 

for these mussels could be lost from onsite activities, but the SWPPP could minimize impacts by 

managing water flow in basins and minimizing turbidity that could change their habitat. Adult 

mussels could be lost or their habitat removed by activities associated with the RMPF, shoreline 

restoration, and maintenance dredging for the proposed Units 3 and 4. If habitat for these 

mussels is found in the area, TPWD might require mitigation activities (e.g., mussels could be 

collected and relocated). 
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NUREG-1937 4-36 February 2011 

Important Habitats 

The Mad Island Wildlife Management Area (WMA) and Clive Runnells Family Mad Island Marsh 

Preserve are to the southwest of the STP site and are important habitats for aquatic organisms 

associated with Matagorda Bay and the Gulf of Mexico. These waterbodies are connected to 

the drainages on the STP site, particularly Little Robbins Slough, and the slough is an important 

contributor of freshwater to these important habitats (NRC 1975, 1986; STPNOC 2010a). 

Stormwater management during site preparation and development activities has the greatest 

potential to change the water quality and quantity in the slough and thus affect the wetlands and 

marshes to the south of the site. STPNOC has indicated that groundwater (from dewatering 

activities associated with the building the proposed power block) and stormwater would be 

collected and disposed into the MCR and not into the onsite waterbodies like the Little Robbins 

Slough. The portion of the Colorado River along the STP site up to the bridge for FM 521 is 

considered EFH within Ecoregion 5 (GMFMC 2004). Section 2.4.2.3 discusses the species and 

life stages included under EFH for the Colorado River. NRC and the Corps are jointly 

consulting with NMFS per Magnuson-Stevens Fishery Conservation and Management Act, and 

the supporting EFH assessment is included in Appendix F. Building activities proposed for 

Units 3 and 4 in and around the Colorado River include improvement at the RMPF and dredging 

around the barge slip. Improvements at the RMPF would not likely affect the fish species 

because they would avoid the area for the duration of the activities. During dredging at the 

barge slip, the fish species might avoid the area due to changes in turbidity from sedimentation 

or during erection and dismantlement of any sedimentation control systems in the river 

(e.g., sheet pile walls). The loss of benthic habitat would discourage the fish from returning to 

the area until their food source and protective habitat recolonizes the area. Improvements at 

the RMPF are not likely to affect the benthic invertebrates (shrimp and stone crab), but dredging 

at the barge slip would temporarily remove habitat for the shrimp and their food source. 

4.3.2.4 Aquatic Monitoring 

No monitoring of aquatic resources is planned for the site preparation and development 

activities onsite or in the transmission corridor. Regulatory agencies have not required 

ecological monitoring of the STP site or its associated transmission line corridors since the mid 

1980s (once the MCR was filled with water), and there is no ongoing monitoring. Monitoring of 

stormwater during site preparation and development activities for proposed Units 3 and 4 under 

TCEQ’s SWPPP would be limited to assessing water quality and does not include monitoring 

aquatic organisms. Inspections of temporary and permanent measures for erosion and 

sediment control would be required to assure that those measures are functioning appropriately 

and are protective of the environment (TCEQ 2008; STPNOC 2010a). 
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February 2011 4-37 NUREG-1937 

4.3.2.5 Potential Mitigation Measures for Aquatic Impacts 

Restoration within the vicinity of areas affected by site preparation and development activities 

would be required prior to notice of termination for the SWPPP. Most likely restoration activities 

would include the removal of erosion and sedimentation control systems (e.g., sediment 

transport barriers), re-grading stream beds and banks that might have been damaged, and revegetation. STPNOC, in response to comments received during the Corps public notice period 

and the DEIS, has proposed to compensate for unavoidable impacts to relatively permanent 

waters resulting from the construction of the heavy haul road by purchasing stream credits from 

the Mill Creek Mitigation Bank (STPNOC 2010e). 

Habitat for State-listed threatened freshwater mussels may be onsite and in the Colorado River. 

If the smooth pimpleback or Texas fawnsfoot are found, TPWD might require mitigation 

activities (e.g., mussels could be collected and relocated). 

TPWD (TPWD 2010), in its comments on the draft EIS, recommended that “STPNOC formulate 

a compensatory mitigation plan for all impacts to fish and wildlife habitat, including wetlands and 

shallow water habitat for the proposed project. This would include impacts to species and 

habitats covered under federal law and state resource habitat types not covered by state or 

federal law. At a minimum, TPWD recommends a replacement ratio of 1:1 for state resource 

habitat types.” Because the applicant plans to restore areas temporarily disturbed by 

construction activities through grading, landscaping, and replanting of these areas, TPWD 

recommended that “all temporary construction impacts be restored to preconstruction contours 

and conditions and that STPNOC prepare a restoration plan and provide this plan to TPWD for 

review and comment” (TPWD 2010). The NRC does not have the statutory authority to require 

the applicant to submit a compensation or restoration plan to a state agency for its review. As 

described below, the impacts of construction and preconstruction to aquatic resources would be 

SMALL. The review team did not rely upon the implementation of TPWD’s recommendations in 

reaching the impact determination. 

4.3.2.6 Summary of Impacts to Aquatic Resources 

Based on information provided by STPNOC and the review team’s independent evaluation, the 

review team concludes that the impacts of preconstruction and construction activities to the 

freshwater, estuarine, and marine aquatic biota and habitats, including impacts on aquatic 

threatened and endangered species and other important species would be SMALL. The LWA 

rule (72 FR 57426) specifically indicates that transmission lines and heavy haul roads are not 

included in the definition of construction. Based on the expectation that no NRC-authorized 

construction activities would affect freshwater, estuarine and marine biota and habitats from 

NRC-authorized construction activities, the NRC staff concludes that the impacts of NRCauthorized construction activities would be SMALL. 
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NUREG-1937 4-38 February 2011 

4.4 Socioeconomic Impacts 

Building activities can affect individual communities, the surrounding region, and minority and 

low-income populations. This evaluation assesses the impacts of building activities and of the 

construction workforce on the region. Unless otherwise specified, the primary source of 

information for this section is the ER (STPNOC 2010a). 

The planned building activities would differ significantly from those required to build the original 

STP Units 1 and 2. Although some activities would be similar, STP Units 1 and 2 were 

constructed almost entirely onsite. For proposed Units 3 and 4, many of the components of the 

U.S. Advanced Boiling Water Reactor (ABWR) nuclear units would be delivered pre-fabricated, 

thus reducing onsite building labor requirements. Although the review team considered the 

entire region within a 50-mi radius of the STP site when assessing socioeconomic impacts, the 

primary region of interest for physical impacts is the area within a 10-mi radius. As described in 

Section 2.5, with regard to social and economic impacts, the entire 50 mi radius is considered, 

but primarily includes Brazoria, Calhoun, Jackson, and Matagorda Counties. Based on 

commuter patterns, populations, and the distribution of residential communities in the area, the 

review team found minimal impacts on other counties within the 50-mi radius in Texas. 

4.4.1 Physical Impacts 

Building activities can cause temporary and localized physical impacts such as noise, odors, 

vehicle exhaust, and dust. Vibration and shock impacts are not expected because of the strict 

control of blasting and other shock-producing activities. This section addresses potential 

building impacts that may affect people, buildings, and roads. 

4.4.1.1 Workers and the Local Public 

The site for proposed Units 3 and 4 is located within an existing power plant facility that includes 

land developed for industrial use, farmland, and undeveloped natural and man-made wetlands. 

Three other industrial facilities are also located within the 10-mi radius. The LCRA Park is about 

6 mi east of the STP site. There are 10 residences within 5 mi of the STP site, with the closest 

residence about 1.5 mi west southwest of the Exclusion Area Boundary (EAB) (STPNOC 

2010a). 

All building activities would occur within the STP site boundary and would be performed in 

compliance with applicable regulatory agencies and permit requirements. While approximately 

5170 people live within 10 mi of the STP site (Appendix G), the people most vulnerable to noise, 

fugitive dust, and gaseous emissions resulting from building activities include construction 

workers and personnel working onsite, people working or living immediately adjacent to the site, 

and transient population such as temporary employees, recreational visitors and tourists 

(STPNOC 2010a). 
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February 2011 4-39 NUREG-1937 

Construction workers would have adequate training and personal protective equipment to 

minimize the risk or potentially harmful exposures. Emergency first-aid care would be available 

at the site, and regular health and safety monitoring would be conducted during building. 

People working onsite or living near the STP site would not experience any physical impacts 

greater than those that would be considered an annoyance or nuisance. Building activities 

would be performed in compliance with local, State, and Federal regulations and site-specific 

permit conditions (STPNOC 2010a). 

Building projects are inherently noisy, but the STP site is fairly isolated from populated areas. If 

exceptionally noisy building activities would be necessary, STPNOC would provide public 

announcements or notifications. Such activities would be performed in compliance with sitespecific permit conditions and local, State, and Federal regulations (STPNOC 2010a). 

Matagorda County is part of the Metropolitan Houston-Galveston Intrastate Air Quality Control 

Region. All areas within the Metropolitan Houston-Galveston Air Quality Control Region are 

classified as attainment areas under Nation Ambient Air Quality Standards, with the exception of 

the Houston-Galveston-Brazoria 8-Hour Ozone Non-attainment Area. The Houston-GalvestonBrazoria area holds non-attainment status for ground-level ozone under the 8-hour standard 

and as of December 3, 2010 is classified at “non-attainment/severe” for ground-level ozone and 

lead (40 CFR 81.344). Temporary and minor effects on local ambient air quality could occur as 

a result of normal building activities. As noted in Section 4.7.1, all equipment would be serviced 

regularly and all building activities would be conducted in accordance with Federal, State, and 

local emission requirements. Therefore, the review team concludes that project-related physical 

impacts to workers and the local public would not be significant. Section 4.7 contains a 

complete review of air quality impacts during preconstruction and construction activities. 

4.4.1.2 Buildings 

Building activities would not affect any onsite or offsite buildings. Onsite safety related buildings 

have been constructed to safely withstand any possible impact, including shock and vibration, 

from activities associated with building new reactors at the STP site (10 CFR Part 50, 

Appendix A). Except for the existing structures on the STP site, no other industrial, commercial, 

or recreational structures would be directly affected by the development of the new facility. 

Therefore, the review team concludes that project-related physical impacts to buildings would 

not be significant. 

4.4.1.3 Roads 

Public roads and railways would transport materials and equipment. The transportation network 

within the four county economic impact area is rural, fed by traffic from urban roadways. 

STPNOC’s building activities are expected to impact the two-lane roadways in Matagorda 

County, particularly FM 521. No significant alterations or development of new roads would be 
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NUREG-1937 4-40 February 2011 

needed, but some roads may need minor repairs or upgrades such as patching cracks and 

potholes, adding run lanes, and reinforcing soft shoulders. STPNOC would repair any damage 

to public roads, markings, or signs caused by building activities to pre-existing conditions or 

better (STPNOC 2010a). 

The site access road that exits onto FM 521 would be maintained with clearly marked signs. 

Construction workers would use either the north or west entrances to the plant rather than the 

primary East Site Access Road, reserved for traffic for Units 1 and 2. The effect of this system 

would be to spread out traffic arrivals and departures and to minimize bottlenecks at the plant 

entrances. A planned heavy haul road from the STP barge facility on the Colorado River to the 

site would be private and contained within the site boundary. STPNOC would select hauling 

routes based on equipment accessibility, existing traffic patterns, and noise restrictions, 

logistics, distance, costs, and safety. Impacts in the surrounding vicinity would be minimized by 

avoiding routes that could adversely affect sensitive areas, such as residential neighborhoods, 

hospitals, schools, and retirement communities. STPNOC also would restrict activities and 

delivery times as much as possible to daylight hours (STPNOC 2010a). Therefore, the review 

team concludes that project-related physical impacts to roads would be minor. 

4.4.1.4 Aesthetics 

Approximately 540 ac on the STP site would need to be cleared and excavated to build the 

proposed Units 3 and 4. All of the clearing and excavation would occur on the STP site; 

however, it may be visible from offsite roads, particularly FM 521 (depending on the activities 

being performed). Clearing and building activities along the riverfront of the Colorado River 

would be visible from the river. No new transmission corridors would be built for Units 3 and 4 

but upgrading current transmission lines in the Hillje transmission line corridor is necessary 

(STPNOC 2010a). The STP site is already aesthetically altered by its existing nuclear power 

plant. Therefore, the review team concludes that project-related physical impacts on aesthetics 

would be minor. 

4.4.1.5 Summary of Physical Impacts 

All building activities would occur within the STP site boundary in areas of previous disturbance. 

Based on the information provided by STPNOC in its ER (STPNOC 2010a) and the NRC’s own 

independent review, the review team concludes that the overall physical impacts of building on 

workers and the local public, buildings, roads, and aesthetics near the STP site would be 

SMALL, and additional mitigation, beyond the applicant’s commitments, would not be 

warranted. 

4.4.2 Demography 

The following assessment of population impacts is based on STPNOC’s estimated peak project 

workforce analysis. The proposed project schedule assumes approximately 7 to 8 years to 
 Construction Impacts at the Proposed Site 

February 2011 4-41 NUREG-1937 

build both units, each being in commercial operation by 2017. STPNOC reviewed several NRC 

studies to determine in-migration assumptions. The highest number of people onsite at any 

given time (approximately month 26 of the building schedule) would be 9021, which includes 

(STPNOC 2010a): 

• 1238 Unit 1 and 2 operations staff 

• 733 Unit 3 and 4 operations staff 

• 5950 construction workers, and 

• 1100 outage workers. 

STPNOC determined the best estimate for the in-migrating workforce for building proposed 

Units 3 and 4 was 50 percent or 2975 workers. Also STPNOC assumes that in-migrating 

workers would settle into the four-county socioeconomic impact area (Matagorda, Brazoria, 

Jackson, and Calhoun Counties) in the same pattern as the current STPNOC employees and 

approximately 80 percent of these workers would bring a family. Using an average family size 

for the workforce of 3.25 people, this would bring the total in-migrating project-related population 

to 8330 (7735 in-migrating family members and 595 workers without family). The Units 3 and 4 

operations workforce was assumed by STPNOC to be 733 at the time of the peak building 

activities, all of whom would be in-migrating. For comparison purposes, the review team will 

also use 733 operations workers and an average family size of 2.74 for the operating workforce 

(Section 5.4) resulting in total in-migrating operations-related population of 2008. Therefore, the 

total expected in-migrating population (building and operations) at the time of peak building 

activity would be 10,338. 

The review team believes that the above assumptions are plausible and assumes that if the inmigrating population follows the same pattern as the existing workforce, then 86 percent 

(8891 people) of the in-migrating population would live in the socioeconomic impact area: 

Brazoria County (2316 people or 22.4 percent), Matagorda County (6275 people or 

60.7 percent), Calhoun County (165 people or 1.6 percent) and Jackson County (134 people or 

1.3 percent) (see Table 2-16). The review team believes the remaining 1462 (14 percent) inmigrating population would settle throughout other counties within the 50-mi region. Most of the 

rest of the construction workers likely would come from the Houston area and Victoria area and 

would count as residents of the region. With these assumptions, there would be net population 

increase of less than one percent in Brazoria, Calhoun, and Jackson Counties and a 16 percent 

increase in population for Matagorda County. Given the magnitude of the estimated population 

increases, the review team determined the influx of workers because of STP project activities 

would only impose minor and temporary demographic impacts in Brazoria, Calhoun, and 

Jackson Counties; however, Matagorda County would likely experience a noticeable but 

temporary impact. If the in-migration rate for construction workers were significantly larger than 

assumed or if more workers brought families, then it is possible that impacts could be greater 

than shown in the remainder of this section. However, there are large nearby supplies of 

construction workers in the cities of Houston and Victoria, and in Brazoria County. In addition, 
Construction Impacts at the Proposed Site 

NUREG-1937 4-42 February 2011 

given the propensity of construction workers to either commute long distances or relocate 

temporarily to a job site without families, the review team believes that the impact of 

in-migration, especially to the smaller counties, would not be larger than that assumed. 

Figure 4-1 characterizes the size of the workforce for the entire project. STPNOC estimates 

NRC-regulated activities to be 66 months long, peaking in year three after the approval of the 

COL. Also shown is the 24 months of preconstruction activity. Not only does the figure show 

the construction workforce but also the operations workforce for STP Units 1 and 2 and 

proposed Units 3 and 4, along with the supplemental outage workers who would be added to 

the operations workforce (STPNOC 2008b). A corresponding table showing total estimated 

numerical values by month for the STP workforce is in the supporting documentation in 

Appendix G. 

Based on its independent analysis, the review team concludes that the demographic impacts of 

building activities would be MODERATE in Matagorda County and SMALL elsewhere. 

Figure 4-1. Total Workforce, STP Units 3 and 4 (STPNOC 2010a) 

4.4.3 Economic Impacts to the Community 

This section evaluates the social and economic impacts on the area within 50 mi of the STP site 

as a result of building the proposed Units 3 and 4. The evaluation assesses the impacts of 

building Units 3 and 4 and the demands placed by the larger workforce on the surrounding 

region. 
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February 2011 4-43 NUREG-1937 

4.4.3.1 Economy 

The impacts of building on the local and regional economy depend on the region’s current and 

projected economy and population. For this analysis, the review team assumed site-preparation 

would begin in 2010 with a commercial operation date of 2016 for Unit 3 and 2017 for Unit 4.

The in-migration of approximately 3708 workers, most bringing their families, would create new 

indirect jobs in the area through a process called the “employment multiplier effect,” whereby a 

new (direct) job in a given area stimulates spending on goods and services that results in the 

economic need for a fraction of a new (indirect) job, typically in service-related industries. The 

cumulative effect of a new direct job workforce being added to an economy induces the creation 

of a number of new indirect jobs. The ratio of new jobs (direct plus indirect) to the number of 

new direct jobs is called the “employment multiplier.” 

In addition, spending by construction workers and STPNOC during building stimulates additional 

spending through a second “multiplier effect,” where each dollar spent on goods and services by 

one person becomes income to another, who saves some money but re-spends the rest. In 

turn, this re-spending becomes income to someone else, who in turn saves a portion and respends the rest, and so on. The percentage by which the sum of all spending exceeds the 

initial dollar spent is called the “earnings multiplier.” 

The U.S. Department of Commerce Bureau of Economic Analysis (BEA), Economics and 

Statistics Division, provides regional multipliers for industry jobs and earnings and a special set 

of multipliers was provided by BEA to STPNOC for Matagorda and Brazoria Counties (STPNOC 

2008b). The review team determined through its own assessment of the area that a more 

appropriate area of socioeconomic impact could be a four-county area rather than the two 

counties used by the applicant (Matagorda, Brazoria, Calhoun, and Jackson); the impact 

multipliers for this larger area would also be larger than for Matagorda and Brazoria alone. 

However, given the sparseness of population and lack of industry in the area, the review team 

believes the BEA multipliers used by the applicant work as a reasonable approximation for this 

analysis. 

For every in-migrating construction worker, STPNOC estimates an additional 0.61 jobs would be 

created in the socioeconomic impact area. Therefore the 2975 construction workers would 

create 1815 indirect jobs for a total of 4790 jobs. For every in-migrating operations worker, 

STPNOC estimates an additional 1.47 jobs would be created in the economic impact area. 

Therefore the 733 operations workers would create 1078 indirect jobs for a total of 1811 jobs. 

The grand total of jobs (direct and indirect) would be 6600. The review team expects some of 

the indirect jobs to be filled by unemployed individuals living in the four counties and possibly by 

spouses of in-migrating construction workers. 
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NUREG-1937 4-44 February 2011 

The employment of a large construction workforce over a 7- to 8-year period would have 

positive economic impacts on the surrounding region. STPNOC estimated that if each inmigrating construction worker earned $53,000 a year, and each in-migrating operations worker 

averaged $72,000 per year, then this large pool of jobs would inject, in the peak employment 

year, more than $200 million into the regional economy, thus reducing unemployment and 

stimulating new business opportunities for housing and service-related industries 

(STPNOC 2010a, 2008c). The largest economic impacts likely would be felt in the Matagorda 

County, particularly in the town of Bay City, since it would house the largest percentage of 

employees. Economic impacts would not be significant in Brazoria County due to its large 

population or in Calhoun and Jackson Counties due to their assumed low increase in 

population. 

After peak project employment in year three, the construction workforce would start to decline 

and produce a decline in related payrolls. There would be a corresponding decline in economic 

impacts for the four counties of the economic impact area. The loss of project-related jobs 

would mean a decrease in indirect jobs through the multiplier effect. However, this decline 

would lag the loss in project-related jobs and would be cushioned by the operations workforce. 

Even though there would be fewer operations workers during building than the number of exiting 

construction workers, they would be permanent residents and would therefore induce a larger 

per-worker multiplier effect (see Section 5.4). 

The review team concludes that beneficial economic impacts could be experienced throughout 

the 50-mi region surrounding the site as a result of building activities at the STP site. In 

Matagorda County these potential economic impacts would be noticeable and beneficial in size 

while economic impacts elsewhere would be minor and beneficial. 

4.4.3.2 Taxes 

Several tax revenue categories would be affected by building proposed Units 3 and 4. These 

include taxes on wages, salaries, and corporate profits; sales and use taxes on building-related 

purchases; workforce expenditures: property taxes related to the new units; and personal 

property taxes on owned real property. 

Personal and Corporate Franchise Taxes 

As stated in Section 2.5.2.2, the State of Texas does not levy a personal income tax. Because 

the franchise tax is calculated based on revenues, no franchise taxes would be assessed during 

building activities. The above mentioned multiplier effect in Section 4.4.3.1 could have an 

indirect effect on the franchise tax. The franchise tax revenue may increase if firms generate 

more revenue from construction workers spending money in their place of business. Since no 

franchise taxes would be paid during the building phase the franchise tax impact would be 

small. 
 Construction Impacts at the Proposed Site 

February 2011 4-45 NUREG-1937 

Sales and Use Taxes 

The area around the proposed site would experience an increase in sales and use taxes 

generated by retail expenditures (e.g., restaurants, hotels, merchant sales, food) by the 

construction workforce. The region would also experience an increase in the sales and use 

taxes collected from construction materials and supplies purchased for the project. STPNOC 

estimates it would spend $32.3 million a year on goods and services during construction of the 

new units (STPNOC 2008a). Any expenditures made by Nuclear Innovation North America 

(NINA), the taxable owners of Units 3 and 4 (as a municipal utility, CPS Energy is not taxable) 

would be subject to two percent local sales tax in Bay City or Palacios on top of the 6.25 percent 

State sales tax. NINA and CPS Energy, have an agreement where NINA would have an 

ownership share of 92.375 percent and CPS Energy would have a 7.625 percent ownership 

interest (STPNOC 2010a). Matagorda County would likely receive a substantial benefit from 

sales tax revenue due to its proximity to the STP site, its relatively small population, and its 

economic base, Matagorda County would likely receive a substantial benefit from sales tax 

revenues. Brazoria County also may see an increase in sales and use tax revenues; however, 

it would likely be a much smaller percentage because of its larger sales and use tax base. Both 

Calhoun and Jackson Counties are expected to have limited STP-related population growth and 

to provide only limited services to the Units 3 and 4 development project; thus, any impact on 

sales and use tax revenues would likely be minimal. 

Property Taxes 

The STP owners paid $6.1 million dollars in property taxes in 2005, which represents threefourths of Matagorda County’s total tax revenues (Table 2-25). The STP owners paid property 

taxes not only to the county but also to the Matagorda County Hospital District, the Navigation 

District #1, the Drainage District #3, the Palacios Seawall District, and the Palacios Independent 

School District (ISD). During construction, tax payments would be based on the cost of building 

Units 3 and 4 and determined in accordance with state law using mutually agreed on appraisal 

formulas or some mutually agreed-upon valuation (STPNOC 2010a). Tax abatements are 

available to the taxable owners of Units 3 and 4 because of Matagorda County’s status as a 

Federal Historically Underutilized Business Zone and Texas Strategic Investment Area. Details 

about such a tax abatement are unavailable at this time. STPNOC would likely pay taxes on 

behalf of the taxable owners of STP Units 3 and 4 to the above districts before operation begins. 

Although the amount currently is unknown, the payments are likely to represent a noticeable 

beneficial impact for Matagorda County. 

Between 2000 and 2005, about 71 percent to 99 percent of Palacios ISD revenues were 

attributed to STP Units 1 and 2. An increased appraised value in the district would increase the 

tax payments made to the ISD, though the amount that the district would get to keep under the 

State’s wealth equalization laws is dependent on factors such as how many new students were 

to enroll into the district. Unless Palacios ISD sees an increase in enrollment, the extra tax 
Construction Impacts at the Proposed Site 

NUREG-1937 4-46 February 2011 

dollars would go to the State. New legislation allows school districts to reduce the taxable value 

of development of nuclear plants. STPNOC would be allowed to defer the effective date of the 

abatement for up to 7 years after the date of the agreement (STPNOC 2010a). The agreement 

would also allow the district and NRG to share in the tax savings. The money the district may 

receive would not be subject to the state’s equalization laws and would not have to be sent back 

to the State. Palacios ISD Board of Trustees approved and signed a tax abatement agreement 

with NRG Energy on June 9, 2008. A fiscal study commissioned by the district found that the 

project would add $3.7 billion to the ISD’s tax base, allowing a reduction in the interest and 

sinking fund (I&S) tax rate from $0.15 to $0.04 with the addition of STP Units 3 and 4, and to 

$0.0615 with just the addition of STP Unit 3 (STPNOC 2010a). 

Another source of revenue from property taxes would be housing purchased by some 

construction workers. In-migrating workers may construct new housing, which would add to the 

counties’ taxable property base, or these workers could purchase existing houses, which would 

drive housing demand and housing prices up, thus slightly increasing values (and property 

taxes levied). The increased housing demand would have little effect on tax revenues in the 

more populated areas. 

4.4.3.3 Summary of Economic Impacts to the Community 

Based on its independent analysis, the review team concludes that the economic impacts of 

building activities would be MODERATE and beneficial in Matagorda County and SMALL and 

beneficial elsewhere. The review team expects project-attributable sales tax revenue impacts 

would be SMALL and beneficial in the economic impact area. The review team concludes that 

building-related property tax revenue impacts also would be MODERATE in Matagorda County 

and the Palacios ISD, but SMALL elsewhere. Based on the information provided by STPNOC 

in its ER (STPNOC 2010a) and the review team’s independent review, the review team 

concludes that the overall economic impacts of building activities on communities near the STP 

site would be MODERATE and beneficial, with SMALL beneficial impacts elsewhere, and no 

mitigation would be warranted. 

4.4.4 Infrastructure and Community Service Impacts 

Infrastructure and community services include transportation, recreation, housing, public 

services, and education. 

4.4.4.1 Transportation 

Building impacts on transportation and traffic would be most obvious on the rural roads of 

Matagorda County, specifically State Highway 60, FM 521, and State Highway 35. Projectrelated impacts on traffic are determined by five elements: 
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February 2011 4-47 NUREG-1937 

• the number of vehicles and timing of shifts for STP workers (building, operations, and 

outage workforces), 

• the number of shift changes for the construction workforce per day, 

• the number and timing of truck deliveries to the site per day, 

• non-STP-related traffic and its projected growth in Matagorda County, and 

• the capacity and usage of the roads. 

STPNOC’s description of expected traffic patterns near the plant (STPNOC 2008a) leads the 

review team to expect that most project traffic would pass through the intersection of FM 1468 

and FM 521. The review team believes the intersection of FM 1468 and FM 521 is a potential 

choke point. Table 4-3 shows the review team’s estimate of the expected project-related traffic 

versus capacity on FM 521, the road most likely to be adversely affected. STPNOC’s analysis 

in their ER assumed three shifts, the first shift including 70 percent of the total labor force, 

25 percent in the second shift, and five percent in the third shift. STPNOC assumed one person 

per vehicle. 

Table 4-3. Calculation of Traffic Impacts on FM 521 from Building Activities at Proposed 

Units 3 and 4, Months 26-35 

Traffic Component 

No. of Vehicles 

Trips at Peak 

Hr (End of Day 

Shift Change) 

Non-STP Traffic, 10 Percent at Shift Change (After 2010) 152 

STP 1 and 2 Plant Workers, Day Shift (70% of Workforce) 867 

STP 1 and 2 Plant Workers, Evening Shift (25% of Workforce) 310 

STP 3 and 4 Construction and Operations Workers, Day Shift (70% of Workforce) 4678 

STP 3 and 4 Construction and Operations Workers, Evening Shift (25% of Workforce) 1671 

Total Traffic at Peak 7677 

Maximum Traffic Threshold (10 percent of 55,200 trips per day) 5520 

Available Capacity -2157 

Source: Review team calculations based on STPNOC 2008a. 

Note: Outage workers are not included because they would be on 12.5-hour shifts and would not be changing crews 

at this time of day. Contractors and truck deliveries would be required to arrive and depart at alternate times than 

shift change workers to alleviate traffic congestion, and thus are not factored into the above analysis. 

While the Texas Department of Transportation (TxDOT) does not provide Level of Service 

(LOS) assessments on roads under its jurisdiction, it does rate “capacity,” which roughly 

corresponds to a LOS “C” (stable flow) (STPNOC 2010a). As discussed in Section 2.5.2.3, 

FM 521 is the main access route to STP and is of special concern. In the TxDOT rating system, 
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NUREG-1937 4-48 February 2011 

FM 521 is a two-lane, rural major collector with a threshold capacity of 55,200 vehicles per day 

or 2300 vehicles per hour. The daily traffic on FM 521 north of STP, measured by the 

2005 Average Annual Daily Traffic count, was 4073 vehicles, 2530 vehicles in the westerly 

direction and 1543 in the easterly direction in a single 24-hour period. STPNOC has assumed 

about one worker per commuting vehicle to estimate project peak traffic. STPNOC has 

estimated that about 67 percent of current vehicle traffic is STP plant-related, about 

2730 vehicle-trips per day (about 1365 workers times one vehicle per worker, twice daily, 

distributed 70 percent to day shift, 25 percent to evening shift and 5 percent to night shift), with 

the other 33 percent attributable to non-STP traffic. The review team expects non-STP traffic, 

1343 vehicle trips, to grow proportionately with county population, 9 percent by 2010 and 

18 percent by 2020 (STPNOC 2010a). This would increase non-STP traffic from 1344 vehicle 

trips per day per day to 1465 in 2010 and 1586 in 2020. STPNOC assumed that 10 percent of 

this traffic would be present during the day/evening shift change. STPNOC also assumed that 

95 percent (70 percent plus 25 percent) of STP Units 1 and 2 worker vehicles and 95 percent 

(70 percent plus 25 percent) of proposed Units 3 and 4 construction workforce vehicles would 

be involved in the day/evening shift change at STP (STPNOC 2010a). The review team added 

95 percent of operations workforce vehicles to this estimate. Added to that are 146 non-STP 

vehicle-trips; this assumes that 10 percent occur during the evening shift change. STPNOC 

also assumed that the maximum hourly threshold was 10 percent of the daily value of 

55,200 vehicle trips, or 5520 (STPNOC 2010a). 

When added to the current estimated peak hour traffic, the peak hour project-related traffic 

would create a cumulative traffic estimate that significantly exceeds road capacity near the plant 

during months 26 through 35 of the development period, with the implicit LOS rating falling 

significantly below “C.” The overall impact in the county, however, likely would be noticeable 

but not as significant. Traffic impacts are likely to be isolated to areas near the plant and only at 

shift changes. They likely would be much lower at off-peak hours and other locations. 

To mitigate these impacts, STPNOC identified mitigation measures that could be part of a 

project management traffic plan produced before development begins. The traffic management 

plan could include such mitigating measures as installing turning lanes at the STP site entrance, 

establishing a centralized parking area away from the site and shuttling construction workers to 

the site, encouraging carpools, and staggering project shifts so they do not coincide with 

operational shifts (STPNOC 2010a). The review team believes that STPNOC and the building 

contractor could alleviate the most serious traffic impacts by changing shift times, by 

encouraging carpooling, and by other traffic control measures. 

In addition to the construction workforce analyzed above, STPNOC would employ 

approximately 1500 to 2000 workers per unit for approximately 17 to 35 days for each outage 

scheduled for each reactor every 18 months. Outage workers would also use FM 521 to access 

the site, but would be on 12.5 hour shifts and would not be on the road at the same time as 
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February 2011 4-49 NUREG-1937 

peak shift change. Truck deliveries would not be allowed during shift change (STPNOC 2008a). 

Rail spur equipment/material deliveries would be scheduled for non-peak traffic times. 

Non-plant related traffic is minimal and is not expected to be impacted by occasional rail traffic 

crossing FM 521. Therefore, the review team concludes that noticeable traffic impacts in 

Matagorda County from the project would warrant mitigation to the extent practicable so they do 

not become destabilizing. 

Rail and Waterways 

STPNOC expects to receive heavy oversized equipment from a 9 mi railroad spur north of the 

plant. Though this spur is currently not in use, when reactivated it is not expected to impact 

other methods of transportation. STPNOC also plans to use a barge slip along the Lower 

Colorado River (3.5 mi SE of the STP site). Heavy equipment and other deliveries would be 

offloaded and brought to the site on a special heavy haul road (2.5 mi long). The barge slip is 

patrolled by the TPWD and the LCRA manages the water quality and supply. STPNOC plans 

on cooperating with the appropriate authorities for barge deliveries including the U.S. Coast 

Guard licensed barge transport contractors, TPWD, and the Corps (STPNOC 2010a). The 

review team expects only minor impacts to railways and waterways from these activities. 

4.4.4.2 Recreation 

Building Units 3 and 4 is not expected to impact the Audubon Christmas Bird Count or the Great 

Texas Coastal Birding Trail. Visitors to the FM 521 River Park may be impacted by the 

increased traffic on FM 521 during shift change; however, it is unlikely that a majority of visitors 

would be there the same time as shift change. This park has a boat landing, trails, and picnic 

areas. Air and noise pollutants would be limited to the STP site (STPNOC 2010a). Because 

the impacts of building would be localized and isolated from major population centers and 

recreation areas, the review team concludes impacts to recreation resources would be minimal. 

4.4.4.3 Housing 

The assumptions behind the review team’s estimated in-migration of workers were established 

in Section 4.4.2 of this chapter. STPNOC noted that housing choice decisions would be 

influenced by workers’ expected length of time at the work site; whether they are accompanied 

by household members; the cost, availability, and condition of local housing; and the distance 

from the family home. Additional factors such as the capacity and quality of local schools and 

the cost of vehicle fuel could influence a family’s decision regarding accompanying the worker to 

the socioeconomic impact region, in turn influencing the type of housing selected (STPNOC 

2008a). However, the review team expects that approximately 3708 workers would migrate into 

the region. Table 2-30 provides information on housing stock in Brazoria, Matagorda, Calhoun, 

and Jackson Counties. 
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NUREG-1937 4-50 February 2011 

The review team’s assumptions in Section 4.4.2 indicate the workforce would require 

approximately 831 housing units in Brazoria County, 2251 in Matagorda County, 59 in Calhoun 

County, and 48 in Jackson County. Based on statistics from the 2000 U.S. Census of 

Population and Housing, all of the counties will most likely have available housing units and 

could absorb the influx of workers. For example, Brazoria County had 8674 vacant units in 

2000; Matagorda County had 4710, Calhoun County had 2796, while Jackson County had 

1209 vacant units (Section 2.5.2.5). Some construction workers would choose to rent a room in 

a local hotel or motel while others relocating might bring campers or mobile homes for the 

duration of their employment. 

Temporary recreational vehicle (RV) parks would likely provide housing to a number of 

construction workers during the building of proposed Units 3 and 4. Matagorda County, Bay 

City, and Palacios currently do not have a land use or zoning plan (STPNOC 2010a). Local 

officials stated additional housing units (both houses and apartments) could be constructed in 

Matagorda County for development of the new units (Scott and Niemeyer 2008). The increased 

demand for housing may increase the price of rental units. The higher prices and increased 

demand for housing could lead to an increase in the rate of new home and temporary housing 

construction. By the time the peak workforce arrives, market forces would have helped alleviate 

the housing/rental prices. STPNOC would maintain communication with local and regional 

government organizations to provide information to decision makers (STPNOC 2010a). The 

review team concludes that while minor housing impacts would occur in Brazoria, Calhoun, and 

Jackson Counties, more noticeable impacts would occur in Matagorda County. 

4.4.4.4 Public Services 

This section describes the public services available and discusses the impacts of building at the 

STP site on water supply and waste treatment, police, fire and medical services, education, and 

social services in the region. The review team recognizes that there is a lag between buildingrelated impacts and the realization of taxes. Therefore the assessments below represent the 

review team’s estimates of impacts without mitigation. 

Water Supply Facilities 

STPNOC separately estimated the groundwater use at the site to support various construction 

and operation activities, and evaluated the total site groundwater usage at each point in time 

from the commencement of proposed Units 3 and 4 construction until both new units are in 

operation. STPNOC analyzed the total maximum groundwater usage at the STP site during 

construction, initial testing, and operation of Units 3 and 4 (for personal consumption and use, 

concrete batch plant operation, concrete curing, cleanup activities, dust suppression, placement 

of engineered backfill, and piping flushing and hydrostatic tests), and the operation of STP Units 

1 and 2. STPNOC concluded that the current operating permit provides adequate groundwater 

supply to support all of these activities. The permit allows groundwater withdrawals up to a limit 
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February 2011 4-51 NUREG-1937 

of 9000 ac-ft over a permit term of approximately 3 years. Historical data on annual groundwater 

withdrawals associated with STP Units 1 and 2 averaged approximately 798 gpm (approximately 

1288 ac-ft/yr) (STPNOC 2010a). Currently, municipal water suppliers in the socioeconomic 

impact area have excess capacity (Table 2-31). The impact to the local water supply systems 

from building-related population growth can be estimated by calculating the amount of water that 

would be required by the total population increase. According to a 2003 EPA report on potable 

water usage, the average person in the United States uses about 90 gpd (EPA 2003). For an 

assumed building-related population increase of 10,338 people, the estimated water usage 

increase would be 930,458 gpd. As discussed in Section 2.5.2.6, excess capacity exists that, 

under the review team’s assumptions, would result in impacts on water supplies that would not 

be significant, and additional mitigation would not be warranted. 

Wastewater Treatment Facilities 

Currently, municipal wastewater treatment facilities in the region have excess capacity 

(Table 2-32). The impact to the local waste water treatment systems from building-related 

population growth can be estimated by calculating the amount of additional volume of waste 

water that would be required by the total population increase. If the potable water usage, about 

90 gpd (EPA 2003), were all converted into waste water and then treated for an assumed 

building-related population increase of 10,338 people, the estimated water treatment increase 

would be 930,458 gpd. As discussed in Section 2.5.2.6, excess capacity currently exists in the 

wastewater treatment systems in the economic impact area. Even if all of the 930,458 gpd 

additional demand for treatment were required just in Matagorda County, the wastewater 

systems have sufficient excess capacity (2.6 MGD) to accommodate the growth with room to 

spare. As discussed in Section 2.5.2.6, excess capacity exists that, under the review team’s 

assumptions, would result in impacts on wastewater treatment that would not be significant. 

Police, Fire, and Medical Facilities 

A temporary increase in population from the construction workforce for a new nuclear facility 

can increase the burdens on local fire and police departments, but this increase is transitory in 

nature. Once the project has been completed, many of the construction workers would leave 

the area, relieving those burdens. During building, the temporary increase in demand for 

community resources could be lower for several reasons. First, larger communities would have 

an easier time assimilating the influx of new people because the additional new population 

comprises a smaller percentage of the communities’ base populations. Second, the more 

communities that host new workers, the less pressure each individual community would 

experience on its infrastructure. Consequently, any incentives STPNOC can provide its 

employees to move into the area in a planned manner would mitigate (but not remove) this 

short-term demand. Third, communities can avoid the long-term commitment to the 

maintenance and operation of infrastructure purchases to fulfill short-term demand increases. 

Instead of purchasing new fire or police equipment, affected communities could lease vehicles 
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NUREG-1937 4-52 February 2011 

or building space. Additional tax revenues from the influx of construction workers would help 

offset the cost to expand local police and fire departments. 

The 2007 citizen to police officer ratios for Brazoria, Matagorda, Calhoun, and Jackson counties 

were 643:1, 420:1, 476:1, and 561:1, respectively. Matagorda has a larger police force relative 

to its population. According to local officials the police protection is adequate in the area at this 

time (STPNOC 2010a). Assuming these same staffing levels, the assumed population increases 

in Brazoria (2316), Matagorda County (6275), Calhoun County (165), and Jackson County (134) 

would increase the citizen to police officer ratio to 648:1 (a 1 percent increase) in Brazoria 

County, 491:1 (a 15 percent increase) in Matagorda County, 480:1 (a 1 percent increase) in 

Calhoun County and 567:1 (a 1 percent increase) in Jackson County. 

The 2007, citizen to firefighter ratios for Brazoria, Matagorda, Calhoun and Jackson counties 

were 539:1, 228:1, 208:1 and 206:1, respectively and increase to 544:1, 267:1, 209:1 and 

208:1, respectively. The increase is a less than one percent increase in Brazoria, Calhoun and 

Jackson counties but a 15 percent increase in Matagorda County. 

Therefore, the review team concludes that the potential impacts of building activities on police 

and fire services in Brazoria, Calhoun and Jackson counties would be minor, but more 

noticeable in Matagorda County and additional mitigation may be warranted. STPNOC could 

mitigate impacts in Matagorda County by communicating with local government officials so that 

any additional police or fire service expansions are coordinated in a timely manner. 

The region is well supplied with hospitals and medical services with four hospitals in Brazoria 

County and one hospital in each of the other three counties. A new regional hospital opened in 

Matagorda County in 2009 with 40 departments and 58 beds. STPNOC expects minor injuries 

incurred during development of proposed Units 3 and 4 to injuries to be treated onsite. More 

serious injuries would be treated at one of the hospitals in the region or in Houston. According 

to Table 2-35, there are 375 staffed beds in the four counties with an average daily census of 

152. The share of the in-migrating population of 10,338 (8,891) in the four-county 

socioeconomic impact area is a 2.4 percent increase over the 2007 total population for the four 

counties. A 2.4 percent increase in the average daily census would bring the number to 156, 

well below the total number of staffed hospital beds in the four counties. Therefore, the review 

team expects the adverse impacts on medical services near the proposed site would be 

minimal. 

Social Services 

Social services in the four county regions are provided by State and local governmental and 

non-governmental organizations. The Texas Health and Human Services Commission 

oversees the Department of Aging and Disability Services, the Department of Assistive and 

Rehabilitative Services, the Department of Family and Protective Services, and the Department 
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February 2011 4-53 NUREG-1937 

of State Health Services, which, collectively, provide the following services: Medicaid, 

Children's Health Insurance Program, Temporary Assistance for Needy Families, Food Stamps 

and Nutritional Programs, Family Violence Services, Refugee Services, and Disaster Assistance 

(STPNOC 2010a). In addition to government-provided services, there are a number of private, 

philanthropic, and religious organizations that provide a wide variety of social services within the 

50-mi radius of the STP site. For example, Table 2-36 shows the list of United Way agencies in 

Matagorda County, together with their client bases and their funding. 

High wage in-migrating workers will not require economic assistance. Current residents who 

currently require economic assistance may be hired by STPNOC contractors. Therefore, 

development of proposed Units 3 and 4 is unlikely to increase the burden on the providers of 

economic assistance, although other social services may see increases in case loads 

(e.g., developmental assistance for children may increase due to population increases). While 

the counterbalancing effects of new jobs and new families cannot be fully quantified, the review 

team believes the overall impact of building activities on social services would be minor. 

4.4.4.5 Education 

The review team expects a net project-related increase of about 2490 school-age children 

distributed throughout the region. Based on the review team’s assumptions concerning the 

geographic distribution of in-migrating population, 558 children would reside in Brazoria County, 

1512 in Matagorda County, 40 in Calhoun County, and 32 in Jackson County. The remaining 

348 in-migrating school-age children would be distributed throughout the remaining counties in 

the region but in such small numbers that they are not considered in this analysis. 

The student populations of public schools of Brazoria, Matagorda, Calhoun, and Jackson 

Counties are 54,578, 7686, 4326, and 3119 respectively, while the private school populations 

are 1429, 133, 67, and 0, respectively (see Section 2.5.2.6). In-migrating students would 

increase the student population by about one percent in Brazoria, Calhoun and Jackson 

counties. Matagorda County’s student population would increase by 20 percent. It is expected 

that most of these students would enroll into Bay City ISD. According to Bay City school 

officials, facilities are adequate. They have a new high school but they may need a couple of 

portable buildings to accommodate the influx of students (Scott and Niemeyer 2008). Other 

Matagorda County ISD school officials stated they had excess capacity to handle an influx of 

students. The review team determined that the impacts on Brazoria, Calhoun, and Jackson 

County school districts would be minimal. The impacts on Matagorda County school districts 

would be more significant. 

4.4.4.6 Summary of Community Service and Infrastructure Impacts 

Based on the information provided by STPNOC, interviews with local planners and officials, and 

the review team’s independent review, the review team concludes that the offsite impacts in the 
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NUREG-1937 4-54 February 2011 

vicinity of the site from building Units 3 and 4 on transportation would be MODERATE and 

adverse during the peak employment period; however, mitigating activities such as those 

identified by STPNOC could reduce these impacts to SMALL and adverse when implemented. 

Because the impacts of building would be localized and isolated from major population centers 

and recreation areas, the review team concludes impacts to recreation resources would be 

SMALL and adverse. Based on the information provided by STPNOC, interviews with local real 

estate agents and city and county planners, and the review team’s independent review, the 

review team expects the housing-related and education impacts of building of Units 3 and 4 

would be SMALL and adverse in Brazoria, Calhoun, and Jackson Counties and MODERATE 

and adverse in Matagorda County. Excess capacity exists in public potable water and 

wastewater systems throughout the region and the review team determined that impacts to 

these systems would be SMALL and adverse, and mitigation would not be warranted. The 

review team concludes that the potential project-related impacts of building activities on police 

and fire services in Brazoria, Calhoun and Jackson counties would be SMALL and adverse, but 

would be MODERATE and adverse in Matagorda County and additional mitigation may be 

warranted. The review team expects adverse impacts on medical and social services near the 

STP site would be SMALL and mitigation would not be warranted. The review team concludes 

in aggregate, Matagorda County would experience MODERATE and adverse public service and 

infrastructure impacts from the project. Impacts in the wider region would be SMALL and 

adverse. Finally, the review team determined the economic impacts of building Units 3 and 4, 

including tax impacts, would be SMALL and beneficial throughout the region, except for 

Matagorda County which would experience a MODERATE beneficial impact from property taxes 

and the Palacios ISD which could do so. 

4.4.5 Summary of Socioeconomic Impacts 

The review team has assessed the activities related to building the proposed Units 3 and 4 and 

their potential socioeconomic impacts in the vicinity and region. Physical impacts on workers 

and the general public include impacts on existing buildings, transportation, aesthetics, noise 

levels, and air quality. Based on information provided by STPNOC and the review team’s 

independent evaluation, the review team concludes that the physical impacts of building 

activities would be SMALL and no further mitigation would be warranted. Based on the above 

analysis, and because NRC-authorized construction activities represent only a part of the 

analyzed activities, the NRC staff concludes that the physical impacts of NRC-authorized 

construction activities would be SMALL, and no mitigation beyond the applicant’s commitments 

would be warranted. 

Social impacts span issues of demographics, economy, taxes, infrastructure, and community 

services. Based on the information provided by STPNOC, review team interviews with city and 

county planners, social service providers, and school district officials, the review team 

concludes that the overall impacts of building activities on the economy in the socioeconomic 
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February 2011 4-55 NUREG-1937 

impact area would be beneficial and SMALL with the exception of a MODERATE beneficial 

impact in Matagorda County and for the Palacios school district. The effect on tax revenues 

would also be beneficial and MODERATE in Matagorda County and SMALL beneficial 

elsewhere. The regional demographic, transportation, housing, police and fire services, and 

education impacts attributed to building would be SMALL for Brazoria, Calhoun, and Jackson 

Counties but MODERATE for Matagorda County. The regional aesthetics and recreation, water 

and wastewater systems, medical systems, and social services impacts attributed to building 

would be SMALL for all four counties. 

The NRC-authorized construction activities represent only a part of the analyzed activities. The 

NRC staff concludes that the economic- and tax-related impacts of NRC-authorized construction 

of Units 3 and 4 would be MODERATE and beneficial in Matagorda County. The regional 

demographic, transportation, housing, police and fire services, and education impacts attributed 

to building would be SMALL for Brazoria, Calhoun, and Jackson Counties but MODERATE for 

Matagorda County. The regional aesthetics and recreation, water and wastewater systems, 

medical systems, and social services impacts attributed to building would be SMALL for all four 

counties. 

4.5 Environmental Justice Impacts 

4.5.1 Analytical Considerations 

The review team evaluated whether the health or welfare of minority and low-income 

populations at those census blocks identified in Section 2.6 could be disproportionately affected 

by the potential impacts of building STP 3 and 4 at the proposed site. To perform this 

assessment, the review team: (1) identified all potentially significant pathways for human 

health, environmental, physical, and socioeconomic effects, (2) determined the impact of each 

pathway for populations within the identified census blocks, and (3) determined whether or not 

the characteristics of the pathway or special circumstances of the minority and low-income 

populations would result in a disproportionate impact on minority or low-income people within 

each census block. The same consideration was given to other minority and low-income 

populations not identified with particular census block groups. To perform this assessment, the 

review team followed the methodology described in Section 2.6.1. In the context of construction 

and preconstruction activities at the STP site, the review team considered the questions outlined 

in Section 2.6.1. As discussed in Section 2.6.3, the review team did not find any evidence of 

unique characteristics or practices in the region. 

4.5.2 Health Impacts 

The review team determined through literature searches and consultations with NRC staff 

health physics experts that the expected building-related level of environmental emissions is 
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well below the protection levels established by NRC and EPA regulations and therefore cannot 

impose a disproportionately high and adverse radiological health effect on minority or lowincome populations 

Section 4.9 assesses the radiological doses to construction workers and concludes that the 

doses would be within NRC and EPA dose standards. Section 4.9 further concludes that 

radiological health impacts to the construction workers for the proposed Units 3 and 4 would be 

SMALL. Therefore, there would be no disproportionately high and adverse impact on lowincome or minority construction workers. From the review team’s investigation, no offsite 

project-related potential pathways to adverse health impacts were found to occur in excess of 

the safe levels stipulated by general health and safety standards. Therefore, the review team 

concludes that the potential for negative impacts from radiological sources would not cause 

health-related disproportionate and adverse impacts on offsite minority and low-income 

populations. 

As described in Section 4.5.1, the potential environmental and physical effects of preconstruction and construction are generally confined within the boundaries leading to no offsite 

health impacts on any population group from those effects. Where there are potential offsite 

non-radiological health effects, the review team did not identify any studies, reports, or 

anecdotal evidence that would indicate any environmental pathway that would physiologically 

impact minority or low-income populations differently from other segments of the general 

population during pre-construction and construction. Moreover, the review team’s regional 

outreach provided no indication of any unique characteristics or practices among minority or 

low-income populations in the 50-mi region that could lead to disproportionately high and 

adverse nonradiological health impacts. No health impacts would be expected on the migrant 

farm worker populations identified in Section 2.6.4, even if they were employed near the STP 

site. 

Any increase in traffic accidents due to heavier traffic is unlikely to have a disproportionate 

impact on any particular population subgroup in the 50-mi region or Matagorda County. The 

roads nearest the plant would be more crowded and can expect more traffic accidents, but 

these increases are likely to be located on the principal commuting routes, which are not located 

in communities with disproportionately large minority or low-income populations. The review 

team found no information to suggest that nearby minority or low-income communities would be 

disproportionately vulnerable to hazards while on the road. Furthermore, in examining 

communities of minority or low-income people, the review team did not identify any such 

community that would be affected disproportionately by nonradiological health items. Therefore, 

non-radiological health effects would not have a disproportionate impact on minority or lowincome populations. 
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February 2011 4-57 NUREG-1937 

4.5.3 Physical and Environmental Impacts 

Building a nuclear power plant is very similar in environmental effects to building any large-scale 

industrial project. The review team determined that the physical impacts from onsite 

construction and preconstruction activities at the proposed STP Units 3 and 4 would attenuate 

rapidly with distance. In addition, the review team did not find any evidence of unique 

characteristics or practices among any minority or low-income populations of interest and 

expect no disproportionately high and adverse physical or environmental impact would be felt by 

any minority or low-income population. The following subsections discuss each of the four 

primary physical-environmental pathways in greater detail. 

4.5.3.1 Soil 

Building activities at the STP site represent the largest source of soil-related environmental 

impacts. However, these impacts would be localized to the site, are sufficiently distant from 

surrounding populations and have little migratory ability, resulting in no noticeable offsite 

impacts. As discussed in Section 2.6.3, the review team did not identify any evidence of unique 

characteristics or practices in the minority or low-income populations that may result in different 

soil-related impacts as compared to the general population. The review team concludes soilrelated environmental impacts during the development of proposed Units 3 and 4 would have no 

disproportionate and adverse impacts on any minority or low-income populations within the 

50-mi region. 

4.5.3.2 Water 

Contaminants, including sediments, are not expected to reach the Lower Colorado River in 

significant amounts because all construction and preconstruction activities would be carried out 

using BMPs (STPNOC 2010a). As discussed in Section 2.6.2, the review team identified a 

river-front community near the Lower Colorado River that may be low-income and may be 

engaged in subsistence fishing. However, with no significant amounts of contaminants reaching 

the river (see Section 4.3.2), there is no environmental pathway through which aquatic 

organisms could cause water-related impacts. As described in Section 4.2, the review team 

expects project-related impacts on surface water to be minimal because no use of surface water 

is proposed and because there would be minimal water quality effects. The review team 

expects all effects on groundwater to be minimal because usage effects would be localized and 

temporary and there would be no effect on groundwater quality. Therefore, the review team 

determined the potential negative offsite environmental effects from impacts to water sources 

would be small; and, consequently, there are no disproportionate and adverse water-related 

impacts on minority and low-income populations to consider. 
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4.5.3.3 Air 

Air emissions are expected from increased vehicle traffic, construction equipment, and fugitive 

dust from project activities. Emissions from vehicles and construction equipment are 

unavoidable, but would be localized and minor, and not disproportionately located in the vicinity 

of identified minority and low-income populations. As discussed in Section 2.6.3, the review 

team did not identify any evidence of unique characteristics or practices in the minority and lowincome populations that may result in different air quality-related impacts as compared to the 

general population (STPNOC 2010a; Scott and Niemeyer 2008). Emissions from fugitive dust 

would be localized within site boundaries, and dust control measures would be implemented to 

maintain compliance with national ambient air quality standards. 

Therefore, the review team determined the negative environmental effects from building-related 

reductions in air quality would be minor, localized, and short-lived for any population in the 

vicinity. Consequently, the review team found no disproportionate and adverse impacts on 

minority and low-income populations because of changes in air quality. 

4.5.3.4 Noise 

Noise levels during building activities may be as high as 113 dBA within the site, but noise 

levels attenuate quickly with distance. Because the loudest noise would register approximately 

65 dBA at the STP site EAB, which is greater than 1000 ft in all directions from the proposed 

Units 3 and 4 footprint, the review team determined impacts from the noise of project activities 

would not lead to offsite noise impacts (see Section 4.8.2). In addition, as discussed in Section 

2.6.3, the review team did not identify any evidence of unique characteristics or practices in the 

minority and low-income populations that may result in different noise-related impacts as 

compared to the general population so there would be no disproportionate and adverse impacts 

on minority and low-income populations. 

4.5.3.5 Summary of Physical and Environmental Impacts 

Based on information provided by STPNOC and the review team’s independent review, the 

review team found no pathways from soil, water, air, and noise that would lead to 

disproportionate and adverse impacts on minority or low-income populations and, therefore, 

there would be no physical or environmental impacts on minorities and low-income populations. 

4.5.4 Socioeconomic Impacts 

Socioeconomic impacts in Section 4.4 were reviewed to evaluate if there would be any projectrelated activities that could have a disproportionate and adverse effect on minority or lowincome populations. That review showed that the likeliest impacts would be from traffic, 

housing, and education. While there likely would be adverse impacts on traffic in the vicinity of 

the plant, these impacts are expected to diminish rapidly with distance from the plant. 

Therefore, given the relatively large distances between the site and the nearest populations of 
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February 2011 4-59 NUREG-1937 

interest, the review team determined that there were no socioeconomic pathways that would 

reach any minority or low-income communities, and that further investigation for unique 

characteristics and practices was not warranted. 

For the routes closest to the STP site, the review team did not identify any populations of 

interest or communities with unique characteristics that could potentially result in different traffic 

impacts as compared to the general population. As discussed in Section 4.4.4.3, the cost of 

rental housing in Matagorda, Jackson, and Calhoun Counties might escalate due to in-migrating 

workers bidding up the price of rent, and that the price increase could lead to a short-term 

MODERATE impact on the general population. However, the review team determined the 

distribution of low-income and minority populations of interest in Matagorda County indicates 

any potential adverse impact of rental price increases likely would not occur disproportionately 

in areas with populations of interest or in communities with unique characteristics. Therefore, 

given the short-term nature of any potential price increases the review team determined there 

would not be disproportionately high and adverse impacts on any minority or low-income 

population or community with unique characteristics from a short-term increase in rental prices. 

If large numbers of construction workers’ children caused the public schools of Matagorda, 

Jackson, and Calhoun Counties to become more crowded, the review team expects that the 

general population within each county would be affected. However, the review team found no 

evidence of any unique characteristic or practice that would result in any minority or low-income 

population to be disproportionately affected by such crowding and, therefore, concludes there 

would be no disproportionate and adverse impacts on minority or low-income populations 

because of changes in socioeconomic conditions. 

4.5.5 Subsistence and Special Conditions 

NRC’s environmental justice methodology includes an assessment of populations of particular 

interest or unusual circumstances, such as minority communities exceptionally dependent on 

subsistence resources or identifiable in compact locations, such as Native American 

settlements. 

4.5.5.1 Subsistence 

STPNOC interviewed community leaders of the minority populations within the analytical area in 

regards to subsistence practices (STPNOC 2010a). The review team also interviewed local, 

State, and county officials, business leaders, and key members of minority communities within 

the four county socioeconomic impact area for information on subsistence practices by minority 

and low-income communities. No subsistence practices such as subsistence agriculture, 

hunting, or fishing were found. However, the riverfront community identified by the review team 

on the Lower Colorado River downstream from the plant (as discussed in Section 2.6.2) may be 

a low income community that may be engaged in subsistence fishing. However, the discussion 
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of aquatic resources in Section 4.3.2 did not indicate that there would be any noticeable adverse 

impact on aquatic resources from building activities, and no pathways were identified from 

building activities that could affect these potential subsistence uses. Many individuals in the 

Vietnamese community in Palacios are shrimpers; however, most of their catch is sold for profit 

not for subsistence living. In addition, although building STP Units 3 and 4 could result in 

temporary minor habitat loss for shrimp, Section 4.3.2 notes that the impact of NRC-authorized 

construction activities on aquatic resources would be minimal. Consequently, the review team 

found no disproportionate and adverse impacts on minority and low-income populations 

because of subsistence activity. 

4.5.5.2 High-Density Communities 

Based on the analysis in Section 2.6, the minority and low-income populations are scattered 

throughout the four-county economic impact area and at greater distances throughout the 50-mi 

region surrounding the STP site. Of particular interest are the Vietnamese and Hispanic 

populations to the southwest of the STP site, in communities centered on Palacios, which is 

actually about 12 mi from the STP site. However, no published information was identified that 

suggests that these communities or any other nearby minority populations have unique 

characteristics or practices that would make them exceptionally vulnerable to environmental 

emissions from building; nor was there any indication in review team discussions with social 

service providers and leaders in these communities that the communities were in vulnerable 

locations or that there were any pre-existing health conditions or cultural practices that would 

make them vulnerable to environmental emissions from STP Unit 3 and 4 development 

(STPNOC 2010a; Scott and Niemeyer 2008). 

There are no Native American communities within the socioeconomic impact area. In analyzing 

the various environmental pathways related to proposed Units 3 and 4 development that could 

affect human populations, the review team notes there are no sources of water or air emissions 

that are expected to reach as far as the Palacios Asian and Hispanic communities, much less 

populations at greater distance. Noise, dust, and similar physical impacts are not expected to 

be noticeable outside the of the STP site. 

Based on information provided by STPNOC and the review team’s independent review, 

including visits to the region and interviews with local officials, the review team found no impact 

pathways from subsistence practices or to high-density communities or any evidence of unique 

characteristics or practices in the minority and low income populations that may result in 

different impacts compared to the general population (STPNOC 2010a; Scott and Niemeyer 

2008). Consequently, the review team found no disproportionate and adverse impacts on 

minority and low-income populations because of affects on high-density communities. 
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February 2011 4-61 NUREG-1937 

4.5.6 Summary of Environmental Justice Impacts 

Based on the information provided by STPNOC and the review team’s independent review, the 

review team concludes that there would be no disproportionate and adverse impacts on 

minorities or low-income populations from any potential pathways or practices of these 

populations. Therefore, the environmental justice impacts from construction and 

preconstruction activities would be SMALL and no additional mitigation would be warranted 

beyond that which the applicant has outlined in its ER. Based on the above analysis, and 

because NRC-authorized construction activities represent only a part of the analyzed activities, 

the NRC staff concludes that the environmental justice impacts of NRC-authorized construction 

activities would be SMALL. 

4.6 Historic and Cultural Resources 

NEPA requires that Federal agencies take into account the potential effects of their 

undertakings on the cultural environment, which includes archaeological sites, historic buildings, 

and traditional places important to local populations. The National Historic Preservation Act of 

1966, as amended (NHPA), also requires Federal agencies to consider impacts to those 

resources if they are eligible for listing on the National Register of Historic Places (such 

resources are referred to as “Historic Properties” in NHPA). As outlined in 36 CFR 800.8(c), 

“Coordination with the National Environmental Policy Act of 1969,” the NRC is coordinating 

compliance with Section 106 of the NHPA in fulfilling its responsibilities under NEPA. 

Construction and preconstruction of new nuclear power plants can affect either known or 

undiscovered cultural resources. In accordance with the provisions of NHPA and NEPA, the 

NRC and the Corps are required to make a reasonable and good faith effort to identify historic 

properties in the area of potential effect and, if such properties are present, determine whether 

or not significant impacts are likely to occur. Identification of historic properties is to occur in 

consultation with the State Historic Preservation Officer (SHPO), Native American Tribes, 

interested parties, and the public. If significant impacts are possible, then efforts should be 

made to mitigate them. As part of the NEPA/NHPA integration, even if no important resources 

(i.e., places eligible for listing on the National Register of Historic Places or meeting the NEPA 

definition of important) are present or affected, the NRC and the Corps are still required to notify 

the SHPO before proceeding. If historic properties are present, then the NRC and the Corps 

are required to assess and resolve adverse effects of the undertaking. 

For a description of the historic and cultural information on the STP site, see Section 2.7. In 

2007, the applicant conducted a reconnaissance-level cultural resources assessment of the 

STP site. It reviewed existing information for the STP site and the area within a 10-mi diameter. 

The applicant concluded that any sites that may have existed onsite would no longer retain their 

integrity because the area was heavily disturbed (STPNOC 2010a). In December 2006, 

STPNOC reported these findings to the SHPO at the Texas Historical Commission (THC); 
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concurrence that there would be no impacts to historic properties was received from the State 

SHPO in January 2007 (STPNOC 2006; THC 2007). Therefore, no further cultural resource 

investigations were required by the State. 

During the site visit in February 2008, the NRC staff reviewed the documentation used by the 

applicant to prepare the cultural resource section of the ER. The review team did not identify 

any cultural resources that would be affected because resources that may have existed prior to 

the construction of STP Units 1 and 2 would have been destroyed during land clearing and 

construction activities. Further, no historic buildings were identified that could be affected by the 

visual impacts of the proposed units. The only locations with viewpoints of the facility are 

located on FM 521 and the Colorado River and there are no historic properties associated with 

these locations.

STPNOC has agreed to follow procedures if historic or cultural resources are discovered during 

ground-disturbing activities associated with building proposed Units 3 and 4. These procedures 

are detailed in STPNOC’s Addendum #5 to procedure No. OPGP03-ZO-0025 Rev. 12 

(Unanticipated Discovery of Cultural Resources) (STPNOC 2008d); the procedure includes 

notification of the SHPO at the THC and affected Tribe(s) or other parties depending on the 

nature of the find. 

For the purposes of NHPA 106 consultation, based on (1) the measures that STPNOC would 

take to avoid adverse impacts to significant cultural resources during construction and 

preconstruction activities, (2) the review team’s cultural resource analysis and consultation, 

(3) the STPNOC commitment to follow its procedures should ground-disturbing activities 

discover cultural or historic resources, and (4) STPNOC consultation with the SHPO at the THC 

that concluded a finding of no impacts to historic properties (STPNOC 2006, THC 2006), the 

review team concludes a finding of no historic properties affected (36 CFR Section 800.4(d)(1)). 

In March 2010, the Texas SHPO concurred with this finding of no historic properties affected 

(THC 2010) and in May 2010, the Alabama-Coushatta Tribe of Texas confirmed that the 

proposed action will cause no known impacts to religious, cultural, or historical resources of 

importance to the Tribe, but requested further consultation if an alternative site is selected or in 

the event of any inadvertent cultural discoveries (Celestine 2010). 

For the purposes of the review team’s NEPA analysis, based on (1) the measures that STPNOC 

would take to avoid adverse impacts to significant cultural resources during construction and 

preconstruction activities, (2) the review team’s cultural resource analysis and consultation, and 

(3) the STPNOC commitment to follow its procedures should ground-disturbing activities 

discover historic or cultural resources, the review team concludes that the potential impacts on 

historic and cultural resources during construction and preconstruction would be SMALL. 

Mitigation may be warranted in the event of an unanticipated discovery; these measures would 

be determined by STPNOC in consultation with the Texas SHPO as well as Native American 

Tribe(s) or other appropriate parties depending on the nature of the find. Based on the above 
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February 2011 4-63 NUREG-1937 

analysis, and because NRC-authorized construction activities represent only a part of the 

analyzed activities, the NRC staff concludes that the potential impacts on historic and cultural 

resources from NRC-authorized construction activities would be SMALL, and no mitigation, 

beyond the applicant’s commitments, would be warranted. 

4.7 Meteorological and Air-Quality Impacts 

Sections 2.9.1 and 2.9.2 describe the meteorological characteristics and air quality of the STP 

site. The primary impacts of building two new units on local meteorology and air quality would 

be from dust from land-clearing and building activities, open burning, emissions from equipment 

and machinery, concrete batch plant operations, and emissions from vehicles used to transport 

workers and materials to and from the site. 

The STPNOC ER (STPNOC 2010a) describes the activities that would be conducted at the STP 

site in Section 3.9S.1 through 3.9S.5. Sections 3.9S.2.2 and 4.4.1.3 of the ER specifically 

address air quality impacts associated with land clearing and building activities. Air quality 

impacts directly associated with these activities are described in the next section (4.7.1); air 

quality impacts associated with transportation of construction workers are addressed in 

Section 4.7.2. 

4.7.1 Construction and Preconstruction Activities 

Development activities at the STP site would result in temporary impacts on local air quality. 

Activities including earthmoving, concrete batch plant operation and vehicular traffic generate 

fugitive dust. In addition, emissions from these activities would contain carbon monoxide, 

oxides of nitrogen, and volatile organic compounds. As discussed in Section 2.9.2, Matagorda 

County is an attainment area for all criteria pollutants for which National Ambient Air Quality 

Standards have been established (40 CFR 81.344). As a result, a conformity analysis for direct 

and indirect emissions is not required (40 CFR 93.153). 

STPNOC stated that it would develop a “Construction Environmental Controls Plan” that 

implements Texas Commission on Environmental Quality requirements prior to beginning 

construction and preconstruction activities. This plan would describe the management controls 

and measures that STPNOC intends to implement to minimize impacts of these activities on air 

quality. The plan would provide for site inspections and environmental inspection reports that 

document the results of the inspections (STPNOC 2010a). Current policies and procedures at 

the STP site address requirements of regulations and permits. These policies and procedures 

may need to be supplemented to address specific measures to mitigate air quality impacts of 

proposed Units 3 and 4. 
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The Construction Environmental Controls Plan would also identify specific mitigation measures 

to control fugitive dust and other emissions. Section 4.4.1.3 of the ER lists mitigation measures 

specifically related to dust control that could be used. These measures include: 

• Limiting speed on unpaved roads 

• Watering unpaved roads 

• Using soil adhesives to stabilize loose dirt surfaces 

• Covering haul trucks when loaded or unloaded 

• Ceasing grading and excavation during high winds and air pollution episodes 

• Phasing grading to minimize areas of disturbed soil, and 

• Revegetating road medians and slopes. 

Finally, the plan would include control strategies to minimize daily emissions by phasing the 

project and performing construction vehicle maintenance. 

Preoperational activities would also result in greenhouse gas emissions, principally carbon 

dioxide (CO2). Assuming a 7-yr construction period and typical construction practices, the 

review team estimates that the total construction equipment CO2 emission footprint for building 

two nuclear power units at the STP site would be of the order of 70,000 metric tons (an 

emission rate of about 10,000 metric tons annually, averaged over the period of construction), 

as compared to a total United States annual CO2 emission rate of 6,000,000,000 metric tons 

(EPA 2009). Appendix I provides the details of the review team estimate for a reference 1000 

MW(e) nuclear power plant. The control strategies to minimize daily emissions of criteria 

pollutants would also reduce greenhouse gas emissions. Based on its assessment of the 

relatively small construction equipment carbon footprint as compared to the United States 

annual CO2 emissions, the review team concludes that the atmospheric impacts of greenhouse 

gases from construction and preconstruction activities would not be noticeable and additional 

mitigation would not be warranted. 

In general, emissions from construction and preconstruction activities (including greenhouse 

gas emissions) would vary based on the level and duration of a specific activity, but the overall 

impact is expected to be temporary and limited in magnitude. Considering the information 

provided by STPNOC and its commitment to conduct “[a]ll site preparation and construction 

activities...in accordance with federal, state, and local regulations,” the review team concludes 

that the impacts from STP Unit 3 and 4 construction and preconstruction activities on air quality 

would not be noticeable because appropriate mitigation measures would be adopted. 

4.7.2 Traffic 

In the ER, STPNOC (2010a) estimates the maximum workforce for proposed Units 3 and 4 

would be about 5950 workers and would exceed 5000 for about a 2-yr period. Many of these 

workers would be doing shift work. STPNOC estimates that about 70 percent of the workforce 
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February 2011 4-65 NUREG-1937 

would be in the first (day) shift, 25 percent would be in the second (swing), and the remaining 

5 percent would be in the third (graveyard) shift (STPNOC 2010a). The workforce needed to 

build Units 3 and 4, combined with the workforce needed for STP Units 1 and 2 (including 

during outage activities), would have a minimal impact on air quality from criteria pollutants. 

The current primary access road to the STP site is a two-lane road that would be likely to 

experience a significant increase in traffic during shift changes that could lead to periods of 

congestion and decreased air quality. However, the overall impact caused by increased traffic 

volume and congestion would be localized and temporary. 

STPNOC (2010a) has stated that a construction management traffic plan would be developed 

before building activities begin. Among other things, the traffic plan would specify separate 

plant entrances for the operations workforce for STP Units 1 and 2 and the construction 

workforce for proposed Units 3 and 4. The traffic plan would address traffic mitigation measures 

that would reduce the impact of increased traffic on air quality. Mitigation measures that are 

typically used to reduce traffic include encouraging car pools, establishing central parking and 

shuttling services to and from the site, and staggering shift changes for operating personnel, 

outage workers, and construction workers. 

Construction workforce transportation would also result in greenhouse gas emissions, 

principally carbon dioxide (CO2). Assuming a 7-yr construction period and a typical workforce, 

the review team estimates that the total construction workforce CO2 emission footprint for 

building two nuclear power plants at the STP site would be of the order of 300,000 metric tons 

(an emission rate of about 43,000 metric tons annually, averaged over the period of 

construction); again this is compared to a total United States annual CO2 emission rate of 

6,000,000,000 metric tons (EPA 2009). Appendix I provides the details of the review team 

estimate for a reference 1000 MW(e) nuclear power plant. Mitigation measures taken to reduce 

traffic would also reduce greenhouse gas emissions. Based on its assessment of the relatively 

small construction workforce carbon footprint as compared to the United States annual CO2

emissions, the review team concludes that the atmospheric impacts of greenhouse gases from 

construction workforce transportation would not be noticeable and additional mitigation would 

not be warranted. 

Based on STPNOC’s commitment to develop a construction management traffic plan and the 

potential mitigation measures listed in the ER, the review team concludes that the impact on the 

local air quality (including the effects of greenhouse gas emissions) from the increase in 

vehicular traffic related to construction and preconstruction activities would be temporary and 

would not be noticeable because appropriate mitigation measures would be adopted. 
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4.7.3 Summary 

The review team evaluated potential impacts on air quality associated with criteria pollutants 

and greenhouse gas emissions during STP site development activities. The review team 

determined that the impacts would be minimal. On this basis, the review team concludes that 

the impacts of building Units 3 and 4 on air quality from emissions of criteria pollutants and CO2

emissions would be SMALL and that no further mitigation is warranted. Because NRCauthorized construction activities represent only a portion of the analyzed activities, the NRC 

staff concludes that the air quality impacts of NRC-authorized construction activities would also 

be SMALL; the NRC staff also concludes that no further mitigation, beyond the applicant’s 

commitments, would be warranted. 

4.8 Nonradiological Health Impacts 

Nonradiological health impacts to the public and workers from construction- and 

preconstruction-related activities include exposure to dust and vehicle exhaust, occupational 

injuries, and noise, as well as the transport of materials and personnel to and from the site. The 

area around the proposed STP site is predominantly rural, characterized by farmland and 

occasional wooded tracts, with a population estimated in 2010 to be 6692 within 10 mi of the 

site (STPNOC 2010a). There are three offsite industrial facilities within a 6-mi radius of the site: 

Equistar Chemicals LP, OXEA Corporation, and a public wharf located at the Port of Bay City 

(STPNOC 2010a). People who are vulnerable to nonradiological health impacts from 

construction- and preconstruction-related activities include: construction workers and personnel 

working at STP; people working or living in the vicinity or adjacent to the site; and transient 

populations in the vicinity (i.e., temporary employees, recreational visitors, tourists). 

4.8.1 Public and Occupational Health 

This section discusses the impacts of building the proposed Units 3 and 4 on public 

nonradiological health and the impacts from site preparation and development on worker 

nonradiological health. Section 2.10 provides background information on the affected 

environment and nonradiological health at and within the vicinity of the STP site. 

4.8.1.1 Public Health 

STPNOC stated in the ER that the physical impacts to the public from development activities at 

the STP site would include dust and vehicle exhaust as sources of air pollution during site 

preparation activities and, if the project is not completed, redress activities (STPNOC 2010a). 

Operational controls would be imposed to mitigate fugitive dust and vehicular emissions such as 

paving disturbed areas, water suppression, covering truck loads and debris stockpiles, reduced 

material handling, limiting vehicle speed, and visual inspection of emission control equipment 

would be instituted. 
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Engine exhaust would be minimized by maintaining fuel-burning equipment in good mechanical 

order. STPNOC (2010a) stated that all equipment would be serviced regularly and operated in 

accordance with local, State, and Federal emission standards. Given the fugitive dust and 

exhaust emission control measures, it is anticipated that no discernible impact on the local air 

quality in the vicinity of the STP site would be realized. 

There would be no general public access to the proposed plant site and as discussed in 

Section 2.10, the nearest residence is approximately 1.5 mi west-southwest of the STP site. 

Given the fugitive dust suppression and vehicle exhaust emission mitigation measures 

discussed above and the general public’s distance away from the STP site, the review 

team expects that the impacts to nonradiological public health from construction and 

preconstruction activities would be negligible. 

4.8.1.2 Construction Worker Health 

U.S. Bureau of Labor Statistics reports take into account occupational injuries and illnesses as 

total recordable cases, which includes those cases that result in death, loss of consciousness, 

days away from work, restricted work activity or job transfer, or medical treatment beyond first 

aid. The review team estimated the annual number of recordable cases based on U.S. and 

Texas total recordable case rates for the year 2007 (BLS 2008a, 2008b). The 2007 recordable 

incidence rates in utility construction (the number of injuries and illnesses per 100 full-time 

workers) for the U.S. and Texas were 5.4 and 3.5, respectively. STPNOC (2010a) reports that 

the average construction workforce for proposed Units 3 and 4 would be 4038 workers 

estimated for a 67-month average period with a peak 12-month workforce of 5950 workers. 

Based on this assessment, an estimated 178 occupational illnesses or injuries could occur 

each year. 

Occupational injury and fatality risks are reduced by strict adherence to NRC and Occupational 

Safety and Health Administration (OSHA) safety standards, practices, and procedures. 

Appropriate State and local statutes also must be considered when assessing the occupational 

hazards and health risks associated with construction. The review team expects that STPNOC 

would fully adhere to NRC, OSHA, and State safety standards, practices and procedures during 

any activities related to site preparation/excavation or building the proposed facility. 

Other nonradiological impacts to workers who are clearing land or building the facility discussed 

in this section include noise, fugitive dust, and gaseous emissions resulting from site 

preparation and development activities. Mitigation measures discussed in this section for the 

public, such as operational controls and practices, would also help limit exposure to workers. 

Onsite impacts to workers also would be mitigated through training and use of personal 

protective equipment to minimize the risk of potentially harmful exposures. Emergency first-aid 

care and regular health and safety monitoring of personnel also could be undertaken. 
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NUREG-1937 4-68 February 2011 

4.8.1.3 Summary of Public and Construction Worker Health Impacts 

Based on mitigation measures identified by STPNOC in its ER, adherence to permits and 

authorizations required by State and local agencies, and the review team’s independent 

evaluation, the review team concludes that the nonradiological health impacts to the public and 

to workers would be minimal, and no further mitigation would be warranted. 

4.8.2 Noise Impacts 

Development of a nuclear power plant project is similar to other large industrial projects and it 

involves many noise-generating activities. Regulations governing noise from activities are 

generally limited to worker health. Federal regulations governing construction noise are found 

in 29 CFR Part 1910 and 40 CFR Part 204. The regulations in 29 CFR Part 1910 deal with 

noise exposure in the construction environment and the regulations in 40 CFR Part 204 

generally govern the noise levels of compressors. The ER states that STPNOC does not 

currently monitor the STP site for noise (STPNOC 2010a). However, the effect of noises 

generated by operation of STP Units 1 and 2 is attenuated over the undeveloped land 

surrounding the plant. In addition, most of the existing plant equipment is located inside various 

plant buildings, which further dampens noises. 

Activities associated with building the new units at the STP site would have peak noise levels in 

the range of 100- to 110 dBA. Construction noise at 10 ft is listed as 110 dBA, and the pain 

threshold is 120 dBA. As illustrated in Table 2-41, noise strongly attenuates with distance. At a 

distance of 50 ft from the source the peak noise levels would generally decrease to the 80 to 

95 dBA range. There are 10 residences within 5 mi of the STP site, with the closest residence 

about 1.5 mi away (STPNOC 2010a). At that distance, the noise from site preparation and 

development would be minimal. 

Building activities at the STP site would be expected to take place 24 hours per day, 7 days per 

week. STPNOC would comply with all applicable Federal and State noise regulations. 

Furthermore, the ER (STPNOC 2010a) lists a number of measures that would be taken if found 

necessary to mitigate the potential adverse effects of construction noise. Mitigation measures 

include mandatory use of hearing protection, inspection and maintenance of construction 

equipment, restriction of noise-related activities to daylight hours, and restriction of delivery 

times to daylight hours. 

According to NUREG-1437 (NRC 1996), noise levels below 60 to 65 dBA are considered to be 

of small significance. As discussed above, it is unlikely that noise levels would be greater than 

60 dBA at the nearest residence. More recently, the impacts of noise were considered in 

NUREG-0586, Supplement 1 (NRC 2002). The criterion for assessing the level of significance 

was not expressed in terms of sound levels, but was based on the effect of noise on human 
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February 2011 4-69 NUREG-1937 

activities and on threatened and endangered species. The criterion in NUREG-0586, 

Supplement 1, is stated as follows: 

The noise impacts...are considered detectable if sound levels are sufficiently high 

to disrupt normal human activities on a regular basis. The noise impacts...are 

considered destabilizing if sound levels are sufficiently high that the affected area 

is essentially unsuitable for normal human activities, or if the behavior or 

breeding of a threatened and endangered species is affected. 

Based on the temporary nature of construction activities and the location and characteristics of 

the STP site, including its large size and exclusion area, as well as the distance to the nearest 

residences, the review team concludes that the noise impacts from building proposed Units 3 

and 4 would be minimal, and further mitigation would not be warranted. 

4.8.3 Impacts of Transporting Construction Materials and Construction 

Personnel to the STP Site 

This EIS assesses the impact of transporting workers and construction materials to and from the 

STP site from the perspective of three areas of impact: the socioeconomic impacts, the air 

quality impacts of dust and particulate matter emitted by vehicle traffic, and potential health 

impacts due to additional traffic-related accidents. Human health impacts are addressed in this 

section, while the socioeconomic impacts are addressed in Section 4.4.1.3, and air quality 

impacts are addressed in Section 4.7.2. The impacts evaluated in this section for two new 

nuclear generating units at the STP site are appropriate to characterize the alternative sites 

discussed in Section 9.3 of this EIS. Alternative sites evaluated in this EIS include the existing 

STP site (proposed), and alternative sites at Allens Creek, Red 2, and Trinity 2. There is no 

meaningful differentiation among the proposed and the alternative sites regarding the 

nonradiological environmental impacts from transporting construction materials and personnel 

to the STP site and alternative sites and are not discussed further in Chapter 9. 

The general approach used to calculate nonradiological impacts of fuel and waste shipments is 

the same as that used for transportation of construction materials and construction personnel to 

and from the STP site. The assumptions made to provide reasonable estimates of the 

parameters needed to calculate nonradiological impacts are discussed below. STPNOC 

estimated that building a new ABWR unit requires approximately 240,000 yd3

 of concrete; 

13,000 tons of structural steel and rebar; 6,500,000 linear ft of cable; and 55,000 linear ft of 

piping (STPNOC 2010a). These quantities would be doubled to account for a two-unit plant. 

Additional information used to develop the nonradiological impact estimates is as follows: 

• The review team assumed that shipment capacities are approximately 13 yd3

 of concrete, 

11 tons of structural steel, and 3300 linear ft of piping and cable per shipment. It was 

assumed that these materials would be transported to the site over an estimated 69-month 
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NUREG-1937 4-70 February 2011 

delivery schedule for site preparation, LWA, if needed, and COL activities outlined in the 

STPNOC ER (STPNOC 2010a). 

• The peak monthly workforce during construction was used to calculate the nonradiological 

transportation impacts. The peak monthly workforce was obtained by adding the monthly 

construction workforce and Unit 3 and 4 operations workforce requirements presented in the 

ER (STPNOC 2010a) and identifying the month with the maximum workforce. The result is 

that a maximum of 6850 workers would travel to and from the site on a daily basis during the 

construction period, including 5950 construction workers and 900 Units 3 and 4 operations 

workers. The operations workforce continues to rise gradually to a total of 959 workers 

combined for both new units while the construction workforce decreases in the months 

following the peak. The review team assumed that one-half of the workers, or 

3425 persons, would be assigned to each unit. Assuming average vehicle occupancy of 

1.14 persons per vehicle (DOT 2004), there would be about 3000 vehicles per day per unit. 

Each person was assumed by the review team to travel to and from the STP site 250 days 

per year. 

• The review team assumed the average shipping distance for construction materials to be 

50 mi one way based on the region of influence. 

• The review team assumed the average commuting distance for construction workers to be 

20 mi one way. This assumption is based on U.S. DOT data that estimates the typical 

commute is approximately 16 mi one way (DOT 2003). 

• Accident, injury, and fatality rates for transporting building materials were taken from Table 4 

in ANL/ESD/TM-150, State-level Accident Rates for Surface Freight Transportation: A 

Reexamination (Saricks and Tompkins 1999). Rates for the State of Texas were used for 

construction material shipments, which are typically conducted in heavy-combination trucks. 

The data provided in Saricks and Tompkins (1999) are representative of heavy-truck 

accident rates and do not specifically address the impacts associated with commuter traffic 

(i.e., workers traveling to and from the site). However, a single source that provided all three 

rates to estimate the impacts from worker transportation to and from the site was not 

available. To develop representative commuter traffic impacts, a source was located that 

provided a Texas-specific fatality rate for all traffic for the years 2004 to 2008 (DOT 2009a). 

The average fatality rate for the 2004 to 2008 period in Texas was used as the base for 

estimating Texas-specific injury and accident rates and adjustment factors were developed 

using national-level traffic accident statistics in National Transportation Statistics 2007 (DOT 

2007). The adjustment factors are the ratio of the national injury rate to the national fatality 

rate and the ratio of the national accident rate to the national fatality rate. These adjustment 

factors were multiplied by the Texas-specific fatality rate to approximate the injury and 

accident rates for commuters in the State of Texas. 

• The DOT Federal Motor Carrier Safety Administration evaluated the data underlying the 

Saricks and Tompkins (1999) rates, which were taken from the Motor Carrier Management 
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February 2011 4-71 NUREG-1937 

Information System, and determined that the rates were under-reported. Therefore, the 

accident, injury, and fatality rates from Saricks and Tompkins (1999) were adjusted using 

factors derived from data provided by the University of Michigan Transportation Research 

Institute (UMTRI 2003). The University of Michigan Transportation Research Institute data 

indicate that accident rates for 1994 to 1996, the same data used by Saricks and Tompkins 

(1999), were under-reported by about 39 percent. Injury and fatality rates were underreported by 16 percent and 36 percent, respectively. As a result, the accident, injury, and 

fatality rates were increased by factors of 1.64, 1.20, and 1.57, respectively, to account for 

the apparent under-reporting. These adjustments were applied to the construction 

materials, which are transported by heavy truck shipments similar to those evaluated by 

Saricks and Tompkins (1999) but not to commuter traffic accidents. 

The estimated nonradiological impacts of transporting materials to the proposed STP site and of 

transporting construction workers to and from the site are illustrated in Table 4-4. The estimates 

would be doubled for building of two units at the STP site. Based on Table 4-4, the 

nonradiological impacts are dominated by transport of construction workers to and from the STP 

site. The estimated total annual construction fatalities related to building the facility represent 

about a 6.5 percent increase above the average 7.4 traffic fatalities per year that occurred in 

Matagorda County, Texas, from 2004 to 2008 (DOT 2009b). Increases for alternative sites 

were about 4.0 percent for the Trinity Site in Freestone County, 4.6 percent for the Allens Creek 

site in Austin County, and 4.8 percent for the Red 2 Site in Fannin County. These increases are 

small relative to the current traffic fatality risks in the areas surrounding the proposed STP site 

and alternative sites. 

Table 4-4. Estimated Impacts of Transporting Workers and Materials to and from the STP Site 

for a Single ABWR 

Accidents per Year 

Per Unit 

Injuries per Year 

Per Unit 

Fatalities per Year 

Per Unit 

Workers 6.7 × 10+1 3.1 × 10+1 4.6 × 10−1

Materials 

 Concrete 5.5 × 10−1

 3.3 × 10−1 2.2 × 10−2

 Rebar, Structural Steel 3.5 × 10−2

 2.1 × 10−2 1.4 × 10−3

 Cable 5.9 × 10−2

 3.6 × 10−2 2.3 × 10−3

 Piping 5.0 × 10−4

 3.0 × 10−4 2.0 × 10−5

Total – Construction 6.8 × 10+1

 3.1 × 10+1 4.8 × 10−1

Based on the information provided by STPNOC, the review team’s independent evaluation, and 

considering the number of shipments of building materials and the number of workers that 

would be transported to the site, the review team concludes that the nonradiological health 

impacts from transporting building materials and personnel to the proposed STP site and 

alternative sites would be minimal, and no further mitigation would be warranted. 
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NUREG-1937 4-72 February 2011 

4.8.4 Summary of Nonradiological Health Impacts 

As part of its evaluation on nonradiological health impacts, the review team considered the 

mitigation measures identified by STPNOC in its ER and relevant permits and authorizations 

required by State and local agencies for building Units 3 and 4. The team evaluated 

nonradiological impacts to public health and to construction workers from fugitive dust, 

occupational injuries, noise, and transport of materials and personnel to and from the proposed 

STP site. No significant impacts related to the nonradiological health of the public or workers 

were identified during the course of this review. Based on information provided by STPNOC 

and the review team’s independent evaluation, the review team concludes that the 

nonradiological health impacts of construction and preconstruction activities associated with the 

proposed Units 3 and 4 would be SMALL, and no further mitigation would be warranted. Based 

on the above analysis, and because NRC-authorized construction activities represent only a 

portion of the analyzed activities, the NRC staff concludes that the nonradiological health 

impacts of NRC-authorized construction activities would be SMALL; the NRC staff also 

concludes that no mitigation, beyond the applicant’s commitments, would be warranted. 

4.9 Radiological Health Impacts 

The sources of radiation exposure for construction workers at STP Units 3 and 4 would include 

direct radiation exposure, exposure from liquid radiological waste discharges, and exposure 

from gaseous radiological effluents from the existing STP Units 1 and 2 during the construction 

phase. For the purposes of this discussion, construction workers are assumed to be members 

of the public; therefore, the dose estimates are compared to the dose limits for the public, 

pursuant to 10 CFR Part 20, Subpart D. STPNOC (STPNOC 2010a) noted that all major 

building activities are expected to occur outside the STP site protected area boundary for STP 1 

and 2, but inside the restricted area boundary. 

4.9.1 Direct Radiation Exposures 

In its ER (STPNOC 2010a), STPNOC identified four sources of direct radiation exposure from 

the STP site: (1) the waste monitor tanks for STP Units 1 and 2 located south of the units; 

(2) the Onsite Staging Facility including Warehouse “D” and outside storage areas; (3) the Old 

Steam Generator Storage Facility; and (4) the proposed Long-Term Storage Facility. In 

addition, STP identified the proposed Unit 3 (including outdoor Condensate Storage Tank) as a 

source of direct radiation exposure to proposed Unit 4 construction workers. At certain times 

during construction, STPNOC would also receive, posses, and use specific radioactive 

byproduct, source, and special nuclear material in support of construction and preparations for 

operation. These sources of low-level radiation are required to be controlled by the applicant’s 

radiation protection program and have very specific uses under controlled conditions. The NRC 

staff did not identify any additional sources of direct radiation during the site visit or during 

document reviews. However, the NRC staff did treat the thermoluminescent dosimeters (TLDs) 
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February 2011 4-73 NUREG-1937 

data differently than STPNOC in estimating the dose to construction workers. The NRC staff’s 

estimate of the direct radiation doses to construction workers are shown in Table 4-5 and 

calculation details are provided in Appendix G. The dose to construction workers from 

byproduct, source, and special nuclear material is expected to have a negligible contribution to 

the values shown in Table 4-5. The numbers in Table 4-5 are different from ER Table 4.5-9 

(STPNOC 2010a). In 1986, prior to operation of STP Units 1 and 2, the background exposure 

rate was measured at the site boundary as 15.4 millirem per quarter (mR/quarter). However, 

some of the current protected area fence line direct radiation measurements by TLDs are lower 

than the 1986 site boundary measurements because the protected area was excavated and 

backfilled with sand and gravel that contained less naturally occurring radiological material than 

exists in the native clay found near the site boundary. Between 2002 and 2006, the exposure 

rate along the protected area fence averaged 12.5 mR/quarter; the NRC staff used this number 

as the background exposure rate for assessing dose rates from existing sources. 

Table 4-5. Direct Radiation Doses to Unit 4 Construction Workers 

Source 

Dose Rate (mrem/yr) 

at Construction Location 

Annual 

Dose to Worker (mrem) 

STP 1 and 2 13.4 3.18 

Old Steam Generator Storage Facility 4.5 1.07 

Long-Term Storage Facility 1 0.24 

Onsite Staging Facility 1 0.24 

STP 3 23 5.5 

Total for STP 1 and 2 19.9 4.72 

Total for STP 1, 2 and 3 42.9 10.2 

4.9.2 Radiation Exposures from Gaseous Effluents

Units 1 and 2 at the STP site release gaseous effluents via vents on the roofs of their 

mechanical auxiliary buildings. The sources of the effluent at STP Units 1 and 2 include 

containment purging, ventilation systems of the auxiliary building and the turbine building as well 

as the gaseous waste processing system (STPNOC 2010a). The gaseous emissions from 

proposed Unit 3 would come from the reactor building plant stack. The stack serves as a 

release point for the reactor building, turbine building and the radwaste building. A Unit 4 

construction worker is more likely to receive a higher dose from gaseous effluents than a 

construction worker on Unit 3, because of the added contribution to dose from Unit 3 operations 

for approximately one year during completion of construction of Unit 4. Therefore, STPNOC 

calculated the dose to Unit 4 construction workers as a bounding estimate for construction 

worker on both Units 3 and 4. STPNOC estimated construction worker dose from STP Units 1 

and 2 gaseous effluents using data from 2005 then doubled the result to account for variability 

in annual releases. The calculated total effective dose equivalent to a Unit 3 construction 

worker from gaseous effluents from STP Units 1 and 2 was 1.9 mrem. The calculated total 

effective dose equivalent to a Unit 4 construction worker from potential gaseous effluents from 
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NUREG-1937 4-74 February 2011 

proposed Unit 3 would be 7.0 mrem, therefore the calculated total effective dose equivalent to a 

Unit 4 construction worker from gaseous effluents from Units 1, 2, and 3 would be about 9 mrem 

(STPNOC 2010a). The NRC staff reviewed STPNOC’s estimates and concluded that they are 

reasonable. 

4.9.3 Radiation Exposures from Liquid Effluents 

STPNOC estimated radiological doses to construction workers from liquid effluents to be small. 

Although construction workers are not expected to be exposed to water pathways at the 

construction site, STPNOC assumed that the construction workers receive the same dose as 

the maximally exposed individual for the water pathway. The pathways for liquid effluents from 

STP Units 1, 2, and 3 to reach humans are sport fish ingestion and exposure to contaminated 

shoreline, only. The contribution from the existing Units 1 and 2 was taken from the maximum 

water pathway dose from 2002 through 2006, as reported in the Radiological Effluent Release 

Reports. The 2004 water pathway dose was also doubled to account for uncertainty resulting in 

a dose of 0.032 mrem (STPNOC 2010a). 

The liquid effluent dose from proposed Unit 3 to the maximally exposed individual due to sport 

fish ingestion and shoreline exposure was calculated as 0.00026 mrem. Again, although Unit 4 

construction workers would likely not be exposed to those pathways at the construction site, 

STPNOC assumed that the construction workers received the same doses as the maximally 

exposed member of the public (STPNOC 2010a). The NRC staff reviewed STPNOC’s 

estimates and concluded that they are reasonable. 

4.9.4 Total Dose to Construction Workers 

The NRC staff estimated the annual direct dose to a construction worker of about 10 mrem, 

assuming an occupancy of 2080 hr/yr. The maximum radiological dose to construction workers 

from gaseous and liquid pathways combined was about 9 mrem (1.9 + 7.0 + 0.032 + 

0.00026 mrem). Therefore, the estimated annual dose to construction workers would be 

approximately 19 mrem based on a 2080 hr/yr occupancy, which is less than the 100 mrem 

annual dose limit to an individual member of the public found in 10 CFR 20.1301. 

4.9.5 Summary of Radiological Health Impacts 

The NRC staff concludes that the estimate of doses to construction workers during building of 

the proposed Units 3 and 4 are well within NRC annual exposure limits (i.e., 100 mrem) 

designed to protect the public health. Based on information provided by STPNOC and the NRC 

staff’s independent evaluation, the NRC staff concludes that the radiological health impacts to 

construction workers for the proposed Units 3 and 4 would be SMALL, and no further mitigation 

would be warranted. Radiation exposure from all NRC-licensed activities including operation of 

STP Units 1 and 2 is regulated by the NRC. Therefore, NRC staff concludes the radiological 
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February 2011 4-75 NUREG-1937 

health impacts for NRC-authorized construction activities would be SMALL, and no further 

mitigation would be warranted. 

4.10 Nonradioactive Waste Impacts 

This section describes the environmental impacts that could result from the generation, 

handling, and disposal of nonradioactive waste during building activities for Units 3 and 4. 

Types of nonradioactive waste that would be generated, handled, and disposed of during 

building activities include construction debris, municipal waste, spoils, dust, stormwater runoff, 

sanitary waste, and air emissions. The assessment of potential impacts resulting from these 

types of wastes is presented in the following subsections. 

4.10.1 Impacts to Land 

Building activities related to the proposed Units 3 and 4 would require environmental 

compliance with documentation of waste removal for containers, packaging, and unused 

materials that are brought onto the STP site. STPNOC plans to provide sufficient trash 

receptacles and management for waste segregation for proper offsite disposal of these types of 

waste (STPNOC 2010a). Hazardous and nonhazardous solid wastes would be managed 

following county and State-specific handling and transportation regulations. Waste minimization 

activities and recycling of certain nonhazardous wastes would be used to further mitigate 

impacts of solid wastes (STPNOC 2010a). 

Excavated materials would be stored onsite in borrow or spoil areas not to exceed 240 ac 

(STPNOC 2010a). Dredged materials not suitable for use as fill would be placed in a 

designated onsite spoils area as indicated in the current STPNOC dredge permit for the 

Colorado River (STPNOC 2010a). 

Wastes generated when building proposed Units 3 and 4 would be handled according to county, 

State, and Federal regulations. County and State permits and regulations for handling and 

disposal of solids, and Corps permits for disposal of dredged spoils, would be obtained and 

implemented. The review team expects solid waste impacts would be minimal and additional 

mitigation would not be warranted. 

Based on the effective practices for recycling and minimizing waste already in place for STP 

Units 1 and 2, and the plans to manage solid and liquid wastes in a similar manner in 

accordance with all applicable State and local requirements and standards, the review team 

expects that impacts to land from nonradioactive wastes generated during the building of 

Units 3 and 4 would be minimal, and no further mitigation would be warranted. 
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NUREG-1937 4-76 February 2011 

4.10.2 Impacts to Water 

Surface water runoff from development activities would be controlled by the development and 

implementation of a SWPPP. STPNOC plans to implement new retention ponds and drainage 

capacity to accommodate surface water runoff in areas disturbed by building activities 

(STPNOC 2010a). Water collected in this manner may then be discharged under a TPDES 

permit. Surface water quality during the development of Units 3 and 4 is discussed further in 

Section 4.2.3.1. 

STPNOC currently has two wastewater treatment facilities that would be replaced or upgraded 

to accommodate increased wastewater generation during project activities (STPNOC 2010d). 

Offsite, both Matagorda and Brazoria County wastewater treatment systems may have the 

capacity to meet the increased generation of wastewater by the project workforce. Brazoria 

County is likely to have a smaller increase in population due to the in-migrating labor force, and 

regional planning for water resources is currently underway. The population increase in 

Matagorda County is likely to be larger as more of the labor force is expected to reside in this 

county. County government would require close communication with STPNOC to prepare for 

and mitigate the increased demand on water resources and wastewater treatment facilities 

(STPNOC 2010a). 

STPNOC would employ the SWPPP for surface water runoff and the TPDES-permitted outfall 

for effluents would comply with Clean Water Act and TCEQ water quality standards. Sanitary 

waste discharge would also be compliant with TPDES limitations. 

Based on the regulated practices for managing liquid discharges, including wastewater, and the 

plans for managing stormwater, the review team expects that impacts to water from 

nonradioactive effluents when building Units 3 and 4 would be minimal and additional mitigation 

would not be warranted. 

4.10.3 Impacts to Air 

As discussed in Sections 4.4.1.1 and 4.7.1, fugitive dust generated by site development 

activities is to be managed: STPNOC plans to control fugitive dust through BMPs such as 

watering roads and employing covers over materials that are transported in open bed trucks 

(STPNOC 2010a). Equipment and heavy haul vehicles used for site preparation and 

development activities would result in air emissions and the increase in vehicle traffic from 

construction workers involved in building Units 3 and 4 would result in vehicle emissions. 

Mitigation of increased emissions through lowering maximum speed and inspection of emission 

control equipment for construction vehicles are measures that would be employed to reduce the 

emissions of gaseous waste (STPNOC 2010a). 

Based on the regulated practices for managing air emissions from construction equipment and 

temporary stationary sources, BMPs for controlling fugitive dust, and vehicle inspection and 
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February 2011 4-77 NUREG-1937 

traffic management plans, the review team expects that impacts to air from nonradioactive 

emissions while building Units 3 and 4 would be minimal, and no further mitigation would be 

warranted. 

4.10.4 Summary of Impacts 

Solid, liquid, and gaseous wastes generated when building Units 3 and 4 would be handled 

according to county, State, and Federal regulations. County and State permits and regulations 

for handling and disposal of solid waste, and Corps permits for disposal of dredged spoils, 

would be obtained and implemented. A revised SWPPP for surface water runoff, and TCEQ 

permits for permitted releases during the construction period would ensure compliance with the 

Clean Water Act and TCEQ water quality standards. Air emissions would be generated by 

vehicles and heavy equipment and site development activities would create fugitive dust when 

building Units 3 and 4. These air quality impacts would be managed through the use of traffic 

management plans, vehicle inspections, and BMPs. Based on information provided by 

STPNOC and the review team’s independent evaluation, the review team concludes that 

nonradioactive waste impacts to land, water, and air would be SMALL and that additional 

mitigation would not be warranted. Because NRC-authorized construction activities represent 

only a portion of the analyzed activities, the NRC staff concludes that the nonradioactive waste 

impacts of NRC-authorized construction activities would be SMALL. The NRC staff also 

concludes that no further mitigation would be warranted. 

Cumulative impacts to water and air from nonradioactive emissions and effluents at the STP site 

are discussed in Sections 7.2 and 7.6, respectively. For the purposes of Chapter 9 

(alternatives), the review team expects that there would be no substantive differences between 

the impacts of nonradioactive waste for the STP site and the alternative sites, and no 

substantive cumulative impacts that warrant further discussion beyond those discussed for the 

alternative sites in Section 9.3. 

4.11 Measures and Controls to Limit Adverse Impacts During 

Construction Activities 

In its evaluation of environmental impacts during building activities for the proposed Units 3 and 

4, the review team relied on STPNOC’s compliance with the following measures and controls 

that would limit adverse environmental impacts: 

• Compliance with applicable Federal, State, and local laws, ordinances, and regulations 

intended to prevent or minimize adverse environmental impacts, 

• Compliance with applicable requirements of permits or licenses required for building the new 

units (e.g., Corps Section 404 Permit and the National Pollutant Discharge Elimination 

System permit) 
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NUREG-1937 4-78 February 2011 

• Compliance with existing STP Units 1 and 2 processes and/or procedures applicable to the 

proposed Units 3 and 4 construction environmental compliance activities for the STP site, 

• Incorporation of environmental requirements into construction contracts, and 

• Identification of environmental resources and potential impacts during the development of 

the ER and the COL process. 

The review team considered these measures and controls in its evaluation of the impacts of 

building Units 3 and 4. Table 4-6, which is the review team’s adaptation from STPNOC’s 

Table 4.6-1 (STPNOC 2010a) lists measures and controls proposed by STPNOC to limit 

adverse impacts during building of proposed Units 3 and 4 at the STP site. 

4.12 Summary of Preconstruction and Construction Impacts 

The impact levels determined by the review team in the previous sections are summarized in 

Table 4-7. The impact levels for NRC-authorized construction are denoted in the table as 

SMALL, MODERATE, or LARGE as a measure of their expected adverse environmental 

impacts, if any. Impact levels for the combined construction and preconstruction activities are 

similarly noted. Socioeconomic categories for which the impacts are likely to be beneficial are 

noted as such in the Impact Level column. 
 Construction Impacts at the Proposed Site

February 2011 4-79 NUREG-1937 Table 4-6. Summary of Measures and Controls Proposed by STPNOC to Limit Adverse Impacts During Construction of Proposed Units 3 and 4 Impact Categories Planned Mitigation and Controls Land-Use Impacts The Site and Vicinity Conduct construction activities using BMPs in accordance with regulatory and permit requirements. Implement environmental controls required in the SWPPP (Stormwater Pollution Prevention Plan) such as weekly compliance inspections, documentation of runoff controls, etc. Clean up and dispose of waste debris from removal of vegetation within the temporary and permanent impact areas. Temporary impact area

s would be graded, landscaped to match the 

surrounding area, and revegetated. 

Restrict stockpiling of soils from spoil mounds and borrow pit soils to designated areas. Stabilize all loose soils onsite through the use of approved erosion control methodologies and soil erosion and sediment control plan. Restrict construction to the designated areas within the STP site. Avoid wetlands. Use appropriate erosion control measures to prevent turbid water, soil deposition, vegetation removal, etc. from impacting drainage features, wetlands and downstream areas through the approved SWPPP. Avoid designated flood zone and other sensitive areas where possible. Stagger work shifts and truck delivery times to reduce the additional traffic during peak hours. 

Transmission Corridors and Offsite Areas

Minimization of land-use impacts during 345-kV switchyard and transmission line rerouting through 

the use of existing access points and corridors. Limit construction activities associated with the new 

onsite switchyard and connecting transmission lines to those areas previously disturbed for construction activities associated with STP Units 1 and 2. 
Construction Impacts at the Proposed Site

NUREG-1937 4-80 February 2011 Table 4-6. (contd) Impact Planned Mitigation and Controls Water-Related Impacts Hydrologic Alterations New drainage ditches and other features such as sediment filters would be used to accommodate surface water runoff from altered drainage areas and the newly constructed impervious areas. Avoid all jurisdictional wetlands. Appropriate erosion control measures would be taken on all drainage features and wetlands to prevent turbid water, soil deposition, vegetation removal, etc. from occurring within those areas or downstream areas through the approved SWPPP. To decrease the volume of surface water runoff created during dewatering/excavating activities of the deeply excavated areas, a groundwater control system would be installed consisting of a slurry wall and perimeter circuit of deep wells in conjunction with sand drains. All other surface water runoff created during the excavation/dewatering activities would be controlled by a series of ditches that drain the water away from construction activities. Proper erosion controls would be used to contain sediments found in the runoff before it is discharged into any jurisdictional water. Local drinking water wells found in the vicinity of the construction area would be unaffected because they are located in the deeper aquifer which is isolated by surficial clays. Dewatering would occur within the shallow aquifer in a limited area for a short period of time. Upon completion of construction, groundwater in the shallow aquifer would return to natural elevations. Water-Use Impacts Limit dewatering activities to only those necessary for construction. Water-Quality Impacts Develop and implement a construction SWPPP and spill response plan. Adhere to applicable regulations and permit requirements found in the TPDES permit. Implement BMPs to prevent the movement of pollutants (including sediments) into wetlands and water bodies via stormwater runoff. BMPs would include the use of erosion control measures such as silt fences to prevent sedimentation and turbid water discharge. Use of vegetated land buffers between water bodies and the construction site would minimize sedimentation impacts. 
 Construction Impacts at the Proposed Site

February 2011 4-81 NUREG-1937 Table 4-6. (contd) Impact Planned Mitigation and Controls Ecological Impacts Terrestrial Ecosystems Limit vegetation removal to only those areas needed for construction. Restoration of the temporary impact areas would be completed in a timely manner upon completion of construction. Effects of increased lighting on birds during construction may be minimized during construction by using downward pointing lighting, hooded lights, and lower wattage lights as appropriate. Animal displacement in adjacent habitats due to noise should be temporary in nature. Animals may return to undisturbed habitats upon completion of construction. Scheduling work during non-nesting periods would minimize impacts to nesting birds caused by noise/movement. Aquatic Ecosystems STPNOC would develop and implement erosion and sediment control plans that incorporate recognized BMPs such as covering all disturbed areas, keeping to a minimum the length of time disturbed soil is exposed to weather, and intercepting and retaining sediment via retention ponds and drainage ditches. Upon completion of construction along stream banks or drainage features, disturbed areas would be rip-rapped or seeded to establish a perennial vegetative cover to prevent erosion. STPNOC would divert excess surface water caused by construction activities into sediment settling ponds prior to release into onsite drainage features. Dewatering activities would be limited, and collected water would be released into areas that meet the SWPPP and TPDES permits. Drainage areas that would be affected by construction represent a small proportion of the drainage areas onsite. These types of habitat are not unique to the area. STPNOC has proposed to compensate for unavoidable impacts to relatively permanent waters resulting from for the construction of the heavy haul road by purchasing stream credits from the Mill Creek Mitigation Bank. 
Construction Impacts at the Proposed Site

NUREG-1937 4-82 February 2011 Table 4-6. (contd) Impact Planned Mitigation and Controls Socioeconomic Impacts Physical Impacts Construction workers would use hearing protection for noise. The public would be notified of impending site development activities that may exceed acceptable noise levels. All site development activities would be performed in compliance with local, State, and Federal regulations. Emergency first-aid care would be available at the site, and regular health and safety monitoring would be conducted during site development. Minimize the potential for dust emissions by using local, State, and Federal regulations. Prepare a dust control plan containing dust control measures such as watering, stabilization of disturbed areas, phased grading to minimize disturbance acreage, covering haul truck beds, etc. Emergency first-aid care would be available at the site, and regular health and safety monitoring would be conducted during site development. Equipment would be serviced regularly to reduce exhaust emissions. Equipment would be operated in accordance with local, State, and Federal emission requirements. Site development activities would be phased to minimize peak hour degradation of local ambient air quality. Emergency first-aid care would be available at the site, and regular health and safety monitoring would be conducted during site development. STPNOC would alert local government agencies to pending road work and complete road repairs and improvements (i.e., patching cracks and potholes, adding turn lanes, reinforcing soft shoulders) in a timely manner to prevent road degradation in the vicinity. 
 Construction Impacts at the Proposed Site

February 2011 4-83 NUREG-1937 Table 4-6. (contd) Impact Planned Mitigation and Controls Social and Economic Impacts To mitigate traffic impacts, STPNOC could develop and implement a site development traffic management plan that would include such measures as turn lane installation where necessary, establishing a centralized parking area with shuttle service, encouraging carpools, and staggering shifts. Other mitigation methods to mitigate potential impacts include: (1) avoiding routes that could adversely affect sensitive areas (e.g., housing, hospitals, schools, retirement communities, businesses) to the extent possible, and (2) restricting activities and delivery times to daylight hours STPNOC would maintain communication with local government and planning officials so that ample time is given to plan for the impact of the site development-related population influx on housing. Mitigation efforts to potential housing shortages would be market-driven (provided by the normal reaction of housing construction to local demand and supply conditions) over time. Site development employment would increase gradually with a peak after 2 or 3 years. This would allow time for construction of new housing. Temporary housing could be constructed as needed. STPNOC would maintain communication with local government and planning officials so that ample time is given to plan for the impact of the site development-related population influx on local water and waste water treatment systems. Mitigation strategies could include reuse, seawater desalination, conservation, and the Lower Colorado River Authority/San Antonio Water System Project. STPNOC would maintain communication with local government officials so that expansions in police and fire services could be coordinated, planned, and funded in a timely manner. Funding for this expansion would be provided through the increased tax revenues from the development project. Short-term solutions to school crowding could be implemented in the form of adding modular classrooms and hiring additional teachers to existing schools. Funding for additional resources would be provided through the increased tax revenues from the site development project. Environmental Justice Analysis of housing availability in Matagorda County determined that the probability of minority and low-income populations absorbing a disproportionate impact through increased rental rates and housing costs is low. Because of this, specific control efforts--for example, rent controls-- would not be necessary. Historic and Cultural Properties Take appropriate actions as required by site procedures following discovery of potential historic or archaeological resources. 
Construction Impacts at the Proposed Site

NUREG-1937 4-84 February 2011 Table 4-6. (contd) Impact Planned Mitigation and Controls Air Quality Conduct site preparation activities “...in accordance with Federal, State and local regulation.” Prepare a Construction Environmental Controls and Construction Management Traffic Plan. Nonradiological Health Impacts STPNOC would provide job training and implement procedures to ensure a safe working environment. Provide first-aid capabilities at the construction site. Radiation Exposure to Construction Workers Doses to construction workers would be maintained below NRC public dose limits (10 CFR Part 20). Nonradioactive Waste Wastes would be handled in accordance with county, State, and Federal regulations. SWPPP would be implemented to manage runoff and releases would conform with State-implemented water quality standards. Air emissions would be reduced by using traffic management plans, implementing BMPs, and using inspected and regularly maintained vehicles and construction machinery. Source: STPNOC 2010a 
 Construction Impacts at the Proposed Site 

February 2011 4-85 NUREG-1937 

Table 4-7. Summary of Construction and Preconstruction Impacts for Proposed Units 3 and 4 

Category Comments

NRC-authorized 

Construction 

Impact Level 

Construction 

and 

Preconstruction 

Impact Level 

Land-Use Impacts 

 Site Some uplands would be permanently 

converted to new land use 

categories. Wetlands would be 

avoided. There would be some land 

use changes as a result of project 

activities but they would not be 

inconsistent with local zoning and 

land-use plans. 

SMALL SMALL 

 Transmission 

 Lines and Offsite 

 Areas 

There would be no new transmission 

lines. Offsite land-use changes 

would not be inconsistent with local 

zoning and land-use plans. 

No impact SMALL 

Water-Related Impacts 

Water Use – 

Surface Water 

No surface water use is proposed 

during construction. 

No impact No impact 

Water Use – 

Groundwater 

Because of the use of a slurry wall 

surrounding the excavation, 

dewatering should have minimal 

impact on groundwater elevation 

outside the construction zone. Any 

impact on the groundwater resource 

from producing water for construction 

would be of localized and temporary. 

SMALL SMALL 

Water Quality – 

Surface Water 

No surface water use is proposed 

during construction. 

SMALL SMALL 

Water Quality – 

Groundwater 

Construction would be conducted 

using BMPs to control spills and 

stormwater runoff. Spills within the 

excavation would be effectively 

isolated by the slurry wall, and 

drawdown resulting from 

groundwater production has minimal 

potential to cause salt water 

encroachment. 

SMALL SMALL 
Construction Impacts at the Proposed Site 

NUREG-1937 4-86 February 2011 

Table 4-7. (contd) 

Category Comments

NRC-authorized 

Construction 

Impact Level 

Construction 

and 

Preconstruction 

Impact Level 

Ecological Impacts 

 Terrestrial 

 Ecosystems 

Construction activities would have 

minimal impacts to terrestrial 

ecological resources and habitat in 

the vicinity of the STP site. 

SMALL SMALL 

 Aquatic 

 Ecosystems

Construction activities would have 

minimal impact on aquatic ecological 

resources and habitat. 

SMALL SMALL 

Socioeconomic 

Impacts

 

Physical Impacts Physical impacts of building activities 

on workers, onsite and offsite 

buildings, and the general public 

would be minimal. Traffic control 

and management measures would 

protect any local roads during site 

development. 

SMALL SMALL 

Demography Percentage of construction workers 

relocating to the region likely would 

be SMALL relative to the existing 

population base except in Matagorda 

County, where the impact could be 

MODERATE. 

SMALL to 

MODERATE 

SMALL to 

MODERATE 

Economic Impacts 

to Community 

Impact of site development would be 

beneficial to local economies. In 

Matagorda County beneficial impacts 

would likely be MODERATE, while 

impacts elsewhere would be SMALL. 

Following site development, SMALL 

to MODERATE negative impacts 

would be incurred due to loss of jobs 

and income. For taxes, MODERATE 

and beneficial in Matagorda County, 

SMALL elsewhere. 

SMALL to 

MODERATE 

(Beneficial) 

SMALL to 

MODERATE 

(Beneficial) 
 Construction Impacts at the Proposed Site 

February 2011 4-87 NUREG-1937 

Table 4-7. (contd) 

Category Comments

NRC-authorized 

Construction 

Impact Level 

Construction 

and 

Preconstruction 

Impact Level 

Infrastructure and 

Community 

Services 

Public services are generally 

adequate in Matagorda County for 

any temporary influx of workers 

resulting from site development at 

the STP site. Some increases may 

be necessary in the number of fire 

and police personnel. Impact on 

education would be MODERATE in 

Matagorda County and SMALL in the 

region. 

SMALL to 

MODERATE 

SMALL to 

MODERATE 

Environmental Justice 

Impacts 

There are no disproportionate and 

adverse impacts on minorities or lowincome populations from any 

potential pathways or practices of 

these populations. 

SMALL SMALL 

Historic and Cultural 

Resource Impacts 

Based on STPNOC procedures and 

commitments to follow those 

procedures, should historical and 

cultural resources be discovered, the 

impacts would be SMALL. 

SMALL SMALL 

Meteorology and Air 

Quality Impacts 

Emissions of criteria pollutants would 

be temporary and limited and carbon 

footprint of construction workforce 

would not be noticeable. 

SMALL SMALL 

Nonradiological Health 

Impacts 

Emission controls and location of the 

STP site would keep nonradiological 

health impacts SMALL. 

SMALL SMALL 

Radiological Health 

Impacts 

Doses to construction workers would 

be maintained below NRC public 

dose limits (10 CFR Part 20). 

SMALL SMALL 

Nonradioactive Waste Impacts to water, land, and air from 

the generation of nonradioactive 

waste would be minimal. 

SMALL SMALL 
Construction Impacts at the Proposed Site 

NUREG-1937 4-88 February 2011 

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U.S. Nuclear Regulatory Commission (NRC). 2000. Environmental Standard Review Plan – 

Standard Review Plans for Environmental Reviews for Nuclear Power Plants. NUREG-1555, 

Vol. 1, Washington, D.C. Includes 2007 updates. 

U.S. Nuclear Regulatory Commission (NRC). 2002. Generic Environmental Impact Statement 

on Decommissioning of Nuclear Facilities, Supplement 1, Regarding the Decommissioning of 

Nuclear Power Reactors. NUREG-0586, Supplement 1, Vols. 1 and 2, Washington, D.C. 

U.S. Nuclear Regulatory Commission (NRC). 2010. Staff Memorandum from Scott Flanders, 

DSER Division Director, to Brent Clayton, RENV Branch Chief, dated December 10, 2010, 

regarding Addressing Construction and Preconstruction Activities, Greenhouse Gas Issues, 

General Conformity Determinations, Environmental Justice, Need for Power, Cumulative Impact 

Analysis, and Cultural/Historical Resources Analysis Issues In Environmental Impact 

Statements. Accession No. ML100760503. 

February 2011 5-1 NUREG-1937 

5.0 Operational Impacts at the Proposed Site 

This chapter examines environmental issues associated with operation of the proposed Units 3 

and 4 at the South Texas Project Electric Generating Station (STP) site for an initial 40-year 

period as described by the applicant, STP Nuclear Operating Company (STPNOC). As part of 

its application for combined construction permits and operating licenses (COLs), STPNOC 

submitted an Environmental Report (ER) that discussed the environmental impacts of station 

operation (STPNOC 2010a). In its evaluation of operational impacts, the U.S. Nuclear 

Regulatory Commission (NRC), its contractors, and the U.S. Army Corps of Engineers (Corps) 

staffs (hereafter known as the “review team”) relied on operation details supplied by STPNOC in 

its ER, STPNOC’s responses to NRC Requests for Additional Information (RAIs), and additional 

information. 

This chapter is divided into 14 sections. Sections 5.1 through 5.12 discuss the potential 

operational impacts on land use, meteorology and air quality, water, terrestrial and aquatic 

ecosystems, socioeconomics, historic and cultural resources, environmental justice, 

nonradiological and radiological health effects, nonradioactive waste, postulated accidents, and 

applicable measures and controls that would limit the adverse impacts of station operation 

during the 40-year operating period. In accordance with Title 10 of the Code of Federal 

Regulations (CFR) Part 51, impacts have been analyzed and a significance level of potential 

adverse impacts (i.e., SMALL, MODERATE, or LARGE) has been assigned by the review team 

to each impact category. In the area of socioeconomics related to taxes, the impacts may be 

considered beneficial and are stated as such. The review team’s determination of significance 

levels is based on the assumption that the mitigation measures identified in the ER or activities 

planned by various state and county governments, such as infrastructure upgrades, as 

discussed throughout this chapter, are implemented. Failure to implement these upgrades 

might result in a change in significance level. Possible mitigation of adverse impacts is also 

presented, where appropriate. A summary of these impacts is presented in Section 5.13. The 

references cited in this chapter are listed in Section 5.14. 

5.1 Land-Use Impacts 

This section contains information regarding land-use impacts associated with operation of 

proposed Units 3 and 4 at the STP site. Section 5.1.1 discusses land-use impacts at the site 

and in the vicinity of the site. Section 5.1.2 discusses land-use impacts with respect to offsite 

transmission line corridors and other offsite areas. 

Most of the STP site is located within the coastal management zone established by the Texas 

Coastal Management Program (STPNOC 2010a). As discussed in Section 2.2.1 of this 

Environmental Impact Statement (EIS), the Texas General Land Office determined in June 2008 
Operational Impacts at the Proposed Site 

NUREG-1937 5-2 February 2011 

that no unavoidable adverse impacts had been found for proposed Units 3 and 4 and that the 

project would be consistent with the goals and policies of the Texas Coastal Management 

Program (STPNOC 2010a). 

5.1.1 The Site 

Onsite land-use impacts from operation of proposed Units 3 and 4 are expected to be minimal 

because little additional land would be affected other than those lands disturbed during 

construction and preconstruction activities, which are discussed in Section 4.1. Some land 

would be used for worker parking and laydown areas during refueling outages. Such land 

would likely be disturbed while building Units 3 and 4. The anticipated salt drift from the two 

mechanical draft cooling towers used solely for the Ultimate Heat Sink (UHS) cooling system 

would occur primarily within the site boundary (discussed further in Section 5.7). The review 

team determined that there would be minimal impacts on vegetation and no significant land use 

changes would be expected. Therefore, based on the information provided by STPNOC and 

the review team’s own independent review, the review team concludes that the land-use 

impacts of operation at the STP site would be SMALL, and additional mitigation would not be 

warranted. 

5.1.2 Transmission Corridors and Offsite Areas 

As discussed in Chapter 3, no new offsite transmission corridors or expansion of existing 

corridors are planned for Units 3 and 4. Consequently, no land-use impacts resulting from 

operation of transmission lines serving the new units are expected. Transmission line corridor 

management practices are discussed in Section 5.3.1.2. 

Some offsite land-use changes can be expected because of operational activities. Possible 

changes include the conversion of some land in surrounding areas to housing developments 

(e.g., recreational vehicle parks, apartment buildings, single-family condominiums and homes, 

and/or manufactured home parks) and retail development to serve plant workers. Property tax 

revenue from the addition of two new units could also lead to additional growth and land 

conversions in Matagorda and Brazoria Counties because of infrastructure improvements 

(e.g., new roads and utility services). Additional information on operation-related infrastructure 

impacts is in Section 5.4.4. While the precise land-use impacts cannot be predicted, the review 

team determined that any land use changes would not be inconsistent with local zoning and 

land use plans. 

Based on the information provided by STPNOC and the review team’s own independent review, 

the review team concludes that the offsite land-use impacts of operating Units 3 and 4 would be 

SMALL, and additional mitigation would not be warranted. 
 Operational Impacts at the Proposed Site 

February 2011 5-3 NUREG-1937 

5.2 Water-Related Impacts 

This section discusses water-related impacts to the surrounding environment from operation of 

the proposed Units 3 and 4 at STP. Details of the operational modes and cooling water 

systems associated with operation of the proposed units can be found in Chapter 3. 

Managing water resources requires understanding and balancing the tradeoffs between various, 

often conflicting, objectives. At the site of the proposed new units, these objectives include 

navigation, recreation, visual aesthetics, a fishery, agriculture, and a variety of beneficial 

consumptive uses of water. The responsibility for any work in, over, or under navigable waters 

of the United States is delegated to the Corps. The Texas Commission on Environmental 

Quality (TCEQ) is responsible for protecting and restoring the quality of Texas’ water, air, and 

land resources. 

Water-use and water-quality impacts involved with operation of a nuclear plant are similar to the 

impacts associated with any large thermoelectric power generation facility. Accordingly, 

STPNOC must obtain the same water-related permits and certifications as other large industrial 

facility discharging to a water body. These permits and certifications include: 

• Clean Water Act Section 401 Certification. This certification is issued by the TCEQ and 

would make sure that operation of the plant would not conflict with State water-quality 

management programs. The TCEQ issued a waiver for the 401 certification for the NRC’s 

action (TCEQ 2010a). 

• Clean Water Act Section 402(p) National Pollutant Discharge Elimination System (NPDES) 

Discharge Permit. This permit would regulate limits of pollutants in liquid discharges to 

surface water. The U.S. Environmental Protection Agency (EPA) has delegated the 

authority for administering the NPDES program in the State of Texas to the TCEQ, which 

issues the Texas Pollutant Discharge Elimination System (TPDES) permits. 

• Clean Water Action Section 404 Permit. The Department of Army permit is required for the 

discharge of dredge and/or fill materials into waters of the United States, including wetlands. 

• Rivers and Harbor Act Section 10 Permit. The Section 10 permit would be issued by the 

Corps for maintenance dredging of the barge slip. However, because the facility has a 

current Section 10 permit associated with existing STP Units 1 and 2, an additional permit 

would not be needed. 

• Water Rights Permit. STPNOC holds a water rights permit from TCEQ (Registration No. 

14-5437) to divert water from the Colorado River for make-up to the Main Cooling Reservoir 

(MCR). See Texas Administrative Code, Title 30, Part 1, Chapters 295 and 297 and Texas 

Water Code, Title 2, Chapter 11. 
Operational Impacts at the Proposed Site 

NUREG-1937 5-4 February 2011 

• Groundwater Use Permit. STPNOC holds an operating permit (Permit No. OP-04122805) 

from the Coastal Plains Groundwater Conservation District (CPGCD), authorizing the use of 

groundwater (CPGCD 2008). STPNOC applies for an update of this permit every three 

years and it would be issued by the CPGCD authorizing continued use of groundwater 

during the operation of proposed Units 3 and 4. STPNOC would apply for a new permit to 

construct new wells within the currently permitted groundwater use limit. See Texas Water 

Code, Chapter 36. 

• Multi-Sector Stormwater Permit. A general or individual permit may be required by TCEQ to 

regulate discharge of stormwater (see Texas Water Code, Chapter 26). In accordance with 

its general permit, STPNOC has an existing Stormwater Pollution Prevention Plan (SWPPP) 

(STPNOC 2010a; TCEQ 2001). According to STPNOC, the STP site existing SWPPP would 

be revised to include the proposed Units 3 and 4 (STPNOC 2010a). 

5.2.1 Hydrological Alterations 

Most of the hydrologic alterations would occur during construction and preconstruction activities. 

Affected water bodies include onsite sloughs, an existing drainage ditch, and site drainages that 

drain to the Colorado River. Section 4.2 describes the water-related impacts that may occur 

while building Units 3 and 4; this section addresses impacts that may occur during operation of 

the two proposed units. 

Make-up water needed for cooling the proposed new reactors under normal operational mode 

would be supplied from the Colorado River using the Reservoir Makeup Pumping Facility 

(RMPF). Additional pumps would be installed in the RMPF for this purpose. A new intake 

structure and a new discharge structure would be constructed within the MCR as part of the 

Circulating Water System (CWS) for Units 3 and 4. To support the operation of Units 3 and 4, 

the MCR normal maximum water surface elevation would be raised from 47 to 49 ft above mean 

sea level (MSL). The normal maximum operating elevation for the original MCR design is 49 ft 

above MSL. The MCR is expected to periodically discharge water using the existing discharge 

pipe to the Colorado River approximately 2 mi downstream from the RMPF (see Figure 2-9). 

The UHS of proposed Units 3 and 4 would use groundwater and the MCR would act as a 

backup source. Groundwater also would be used for power block operational uses, fire 

protection systems, and potable and sanitary systems. 

There may be periodic dredging of the RMPF forebay and dredging of the barge slip during the 

operation of proposed Units 3 and 4 (STPNOC 2010a). The effects of these dredging activities 

on surface water quality are discussed in Section 5.2.3.1. 

Hydrologic alterations during the operation of the proposed new units are expected to be limited 

to the following activities: 
 Operational Impacts at the Proposed Site 

February 2011 5-5 NUREG-1937 

• Alteration of discharge in the Colorado River below the RMPF because of diversion of 

make-up water to the MCR 

• Alteration of discharge and water quality during MCR discharge events 

• Alteration of groundwater elevations/potentiometric heads because of operation of water 

supply wells 

• Alteration to site hydrology because of raising of the normal maximum MCR operating level, 

re-grading and re-contouring, placement of new buildings, newly paved areas, and new site 

drainage ditches. 

5.2.2 Water-Use Impacts 

A description of water-use impacts to surface water and groundwater is presented in the next 

sections. The water resource usage by proposed Units 3 and 4 operations is limited to diverting 

water from the Colorado River for MCR make-up water needs and pumping groundwater for 

make-up to UHS basins, potable water supply, sanitary uses, and service water needs. 

In Texas, water use is regulated by the Texas Water Code. As established by Texas Water 

Code, surface water belongs to the State of Texas (Texas Water Code, Chapter 11, 

Section 11.021). The right to use surface waters of the State of Texas can be acquired in 

accordance with the provisions of the Texas Water Code, Chapter 11. In Texas, surface water 

is a commodity. Since the Colorado River Basin is currently heavily appropriated, future water 

users in this basin would likely obtain surface water by purchasing or leasing existing 

appropriations. Regarding groundwater, Texas law has allowed landowners to pump the water 

beneath their property without consideration of impacts to adjacent property owners 

(NRC 2009b). However, Chapter 36 of Texas Water Code authorized groundwater 

conservation districts to help conserve groundwater supplies. Chapter 36, Section 36.002, 

Ownership of Groundwater, states that ownership rights are recognized and that nothing in the 

code shall deprive or divest the landowners of their groundwater ownership rights, except as 

those rights may be limited or altered by rules promulgated by a district. Thus, groundwater 

conservation districts with their local constituency offer groundwater management options 

(NRC 2009b). The existing STP Units 1 and 2 use current STPNOC water rights granted by the 

TCEQ and the conditions of the existing STPNOC-Lower Colorado River Authority (LCRA) 

water contract to withdraw surface water from the Colorado River. Groundwater used by STP 

Units 1 and 2 is withdrawn from the Deep Aquifer under STPNOC's existing CPGCD permit. 

STPNOC has stated that the proposed Units 3 and 4 would operate within the limits of these 

existing surface water and groundwater appropriations (STPNOC 2010a). 
Operational Impacts at the Proposed Site 

NUREG-1937 5-6 February 2011 

5.2.2.1 Surface Water 

STPNOC's current water rights and diversion conditions are described in Section 2.3.2.1. In 

addition, STPNOC would have access to 20,000 ac-ft/yr (12,400 gpm) of firm water for 

proposed Units 3 and 4 which would be delivered from LCRA-owned water rights within 

upstream reservoirs. 

According to STPNOC’s analysis, Units 3 and 4 would result in an additional induced 

evaporation of 21,600 gpm (34,850 ac-ft/yr) during normal and 23,190 gpm (37,430 ac-ft/yr) 

during maximum conditions (STPNOC 2009a). The normal and maximum conditions refer to 93 

and 100 percent load factors, respectively (STPNOC 2010a). Based on the assumption that 

approximately half of the reject heat load would be dissipated via evaporation, the review team 

determined that STPNOC’s estimate of additional induced evaporation for proposed Units 3 and 

4 is not unreasonable. 

To satisfy the increased surface water demand at the STP site related to operation of proposed 

Units 3 and 4, STPNOC could use the currently unused portion of the permitted 102,000 ac-ft/yr 

(63,250 gpm). Existing STP Units 1 and 2 withdrew an average of 22,991 gpm (37,084 ac-ft/yr) 

from the Colorado River from 2001 through 2006 (STPNOC 2010a). Therefore, an average of 

40,260 gpm (64,940 ac-ft/yr) of the currently permitted amount is unused. As stated in Section 

2.3.2.1, the currently available surface water resource near the STP site, represented by the 

average of mean annual discharges during water years 1949 to 2008 at the Bay City U.S. 

Geological Survey (USGS) streamflow gauge, is estimated to be 2629 cfs (1,180,000 gpm or 

1,903,000 ac-ft/yr). As stated in Section 2.3.2.1, the current STP water use for Units 1 and 2 

during normal operations is 2 percent (34,821 ac-ft/yr, based on a 3-year average for existing 

units [STPNOC 2010a], of use with 1,903,000 ac-ft/yr of available surface water resource), and 

the proposed STP water use for the existing and proposed units during normal operations would 

be 4 percent (34,821 ac-ft/yr, based on a 3-year average for existing units [STPNOC 2010a], 

plus 37,430 ac-ft/yr, based on the projected long-term average MCR evaporation at full load 

operating condition for Units 3 and 4 [STPNOC 2009a], of use with 1,903,000 ac-ft/yr of available 

surface water resource). As stated in Section 2.3.2.1, the current STP water use for Units 1 and 

2 during normal operations is estimated to be 3 percent of Texas Water Development Board 

(TWDB)-estimated Region K water supplies in 2010 (TWDB 2007). The proposed STP water 

use for all four units during normal operations would be 8 percent of TWDB-estimated water 

supplies in 2060 if no water management strategies are implemented in Region K. The increase 

in water use at the STP site to support the operations of Units 3 and 4 would be an increment of 

2 percent of the available resource and an increment of 3 percent of the 2010 TWDB-estimated 

water supplies of Region K. The review team determined that this associated 2 percent 

decrease in Colorado River discharge below the RMPF would be smaller than the typical 

accuracy of streamflow measurement and therefore the impact on surface water use in the 

Colorado River Basin would be minimal. 
 Operational Impacts at the Proposed Site 

February 2011 5-7 NUREG-1937 

To support the operation of STP Units 3 and 4, new pumps would be installed in the RMPF to 

increase the withdrawal capacity to 1200 cfs. The RMPF contains 24 traveling screens, each of 

10-ft width (STPNOC 2010d). The minimum withdrawal from the Colorado River during 

operation of STP Units 3 and 4 would be 60 cfs, equal to the pumping capacity of the smallest 

installed pump. Because STPNOC is only allowed to withdraw 55 percent of the discharge in 

the Colorado River exceeding 300 cfs, the review team estimated that the minimum discharge in 

the Colorado River for a 60-cfs withdrawal would be 409 cfs. Similarly, the review team 

estimated that the minimum discharge in the Colorado River to withdraw the maximum of 

1200 cfs would be 2482 cfs. No stage-discharge data is available for the Colorado River near 

the RMPF. Therefore, the review team could not determine the water surface elevations of the 

Colorado River for the two discharges, 409 and 2482 cfs. The review team conservatively 

assumed that the water surface elevation in the Colorado River would be at least at mean sea 

level, which corresponds to average tidal conditions under no upstream freshwater discharge 

conditions. 

The bottom of the traveling screens in the RMPF is located at 10 ft below MSL. Therefore, the 

review team estimated that the area of the 24 screens would be 2400 ft2

 with the water surface 

elevation in the Colorado River at mean sea level. The average approach velocities in front of 

the traveling screens for withdrawals of 60 and 1200 cfs are estimated by the review team to be 

0.025 and 0.5 fps, respectively. It should be noted that the review team’s assumption that the 

water surface elevation in the Colorado River during the withdrawal is conservative and the 

actual water surface elevation is likely higher, particularly for a discharge of 2482 cfs. 

Therefore, the review team concludes that the average approach velocities estimated above are 

the maximum possible for the stated withdrawal conditions. 

Based on a review of the LCRA-STPNOC water contract (LCRA-STPNOC 2006), the review 

team determined that STPNOC could withdraw water at a rate of 1200 cfs from the Colorado 

River using the RMPF even when the river water surface elevation is close to mean sea level. 

This condition is likely to occur under prolonged droughts when STPNOC would receive firm 

water from LCRA. However, the review team determined that the Colorado River water quality 

during these low water conditions would not improve the MCR water quality, therefore there 

would be minimal or no pumping during these low water conditions. The review team therefore 

determined that withdrawal of 1200 cfs from the Colorado River when the water surface 

elevation is close to mean sea level would be infrequent. Consequently, the review team 

concluded that the likelihood of the maximum approach velocity reaching 0.5 fps would be 

very low. 

The requirement limiting STPNOC withdrawals to 55 percent of Colorado River when the river 

flow exceeds 300 cfs would not be in effect if LCRA supplies firm water to support the operation 

of the plant under a prolonged drought condition. The review team expects that, during these 

low-flow conditions, the Colorado River near the RMPF would be influenced by tidal conditions, 
Operational Impacts at the Proposed Site 

NUREG-1937 5-8 February 2011 

making the water surface elevation at the site always above mean sea level during severe 

drought conditions. During operation of STP Units 1 and 2, STPNOC has never used the firm 

water to support the operation of Units 1 and 2 even with severe drought conditions. The 

extended drought condition that would require STPNOC to ask LCRA for delivery of firm water 

would occur only infrequently. Therefore, the review team concluded that the maximum 

approach velocity of 0.5 fps would not occur under the most severe drought condition when firm 

water delivery is not being made. 

STPNOC performed a water budget and water quality analysis of the MCR using hypothetical 

scenarios where the existing units and all four units were assumed to operate over a long period 

(STPNOC 2008a, 2009c, d, e, f). STPNOC developed a water budget and water quality model 

of the MCR. Water flowing into the MCR consists of diverted makeup water from the Colorado 

River and rainfall. Water flowing out of the MCR consists of natural and induced(a) evaporation, 

seepage, water discharged from the MCR spillway, and water discharged from the MCR to the 

Colorado River. 

As described in Section 2.3.1.1, STPNOC currently diverts water from the Colorado River 

following a set of requirements specified by the STPNOC-LCRA water contract (STPNOC 

2009b). To support the operation of proposed Units 3 and 4, STPNOC would withdraw makeup 

water from the Colorado River and discharge MCR water to the Colorado River to (1) maintain 

the MCR water level at or above 27 ft above MSL (applicable to two or four-unit operation) and 

(2) maintain the MCR water quality below 3000 microsiemens per centimeter (μS/cm) for 

specific conductivity (STPNOC 2009b). When the MCR water level is between 40 and 49 ft 

above MSL, STPNOC would only withdraw relatively high-quality water (specific conductivity 

less than 2100 μS/cm or total dissolved solids less than 1260 mg/L) from the river subject to the 

LCRA water contract (STPNOC 2009b). When the water level in the MCR is between 36 and 

40 ft above MSL, STPNOC would withdraw water from the river if its quality is better than MCR 

water quality subject to the LCRA water contract. With the MCR water level at 37 ft above MSL, 

STPNOC would request LCRA for delivery of firm water. When the MCR water level is between 

32 and 36 ft above MSL, STPNOC would withdraw water if the river water conductivity is less 

than 10,000 μS/cm or its total dissolved solids are less than 6000 mg/L subject to the LCRA 

water contract. When the MCR water level falls below 35 ft above MSL, LCRA would begin 

delivery of firm water for the MCR and withdrawal of firm water from the river by STPNOC would 

not be subject to the LCRA water contract. 

Natural and induced evaporation from the MCR were estimated using a one-dimensional multilayer thermal model (STPNOC 2009d). The thermal model uses the surface area and volume 

of the MCR, and time series of relative humidity, dry bulb air temperature, wind speed, cloud 

cover, and clear sky incoming solar radiation. The thermal model also requires plant operation 

data including the circulating water flows, electrical output, and MCR water surface elevations. 

 

(a) Induced evaporation is caused by waste heat discharged to the MCR. 
 Operational Impacts at the Proposed Site 

February 2011 5-9 NUREG-1937 

STPNOC calibrated the thermal model using MCR operational data and meteorological data 

from the Victoria Regional Airport. The calibration was carried out to best fit the measured MCR 

water temperatures. 

To understand the incremental impacts of the long-term operations of Units 3 and 4 on the 

water and aquatic resources of the Colorado River, STPNOC used the MCR water budget and 

water quality model to simulate hypothetical operations of (1) the existing units and (2) the 

existing and proposed units, using the longest period of available streamflow and meteorological 

records to examine the effects of the proposed units on water use and the effects of MCR 

discharges on water quality of the Colorado River (STPNOC 2009c, d). The first case, the 

operation of existing units, represents the base case at the STP site. The second case, the 

operation of the existing and proposed units, represents the proposed future condition at the 

STP site. The simulations used the daily water budget of the MCR based on the principle of 

conservation of mass. The water budget of the MCR used daily inflows into the MCR consisting 

of the volume of makeup water pumped into the MCR from the Colorado River, the volume of 

precipitation entering the MCR, and the volume of firm water received from the LCRA and put 

into the MCR. The daily outflows from the MCR consisted of the volume of natural and induced 

evaporation, the volume of seepage loss, and the volume of MCR discharge to the Colorado 

River. The difference between the daily inflows and outflows equaled the net daily change in 

the volume of water stored in the MCR. The simulations were carried out for two Lower 

Colorado River streamflow scenarios, (1) historical streamflow (a time period of May 1948 

through December 2005); and (2) projected streamflow accounting for Lower Colorado River 

Authority-San Antonio Water System (LCRA-SAWS) withdrawals (a time period of May 1948 

through December 1998). STPNOC conservatively assumed that the four units would operate 

continuously at 100 percent load. 

The review team performed an independent assessment of STPNOC’s assumptions, data, and 

MCR operating rules built into the water budget and water quality model. The review team 

determined that STPNOC appropriately used the historical and LCRA-SAWS projected 

streamflows of the Colorado River and meteorological data from nearby stations in the water 

budget model (STPNOC 2009c). The review team also determined that STPNOC appropriately 

used water and heat balance equations that are commonly used in practice (STPNOC 

2009c, d). The LCRA conditions on water withdrawals from the Colorado River are included in 

STPNOC’s water budget and water quality model. STPNOC reported the calibration of the 

thermal model using measured MCR water temperatures near the circulating water intake and 

discharge locations (STPNOC 2009d) STPNOC reported verification of the water budget and 

the water quality model results with measured MCR water surface elevations and MCR water 

conductivities (STPNOC 2009d). The review team’s assessment of the verification determined 

that the model simulated the measured MCR water surface elevations and conductivities with 

acceptable accuracy. The review team also determined that natural and induced evaporation 

from the MCR were simulated by a thermal model commonly used to predict evaporation from 
Operational Impacts at the Proposed Site 

NUREG-1937 5-10 February 2011 

cooling ponds. The review team determined that these estimates are not unreasonable for the 

MCR and the heat loads of the four STP units. Therefore, the review team used the water 

budget and water quality model results, provided by STPNOC, to determine the water-related 

impacts at the STP site. Table 5-1 below summarizes the results of STPNOC simulations. 

Table 5-1. Summary Statistics of Simulated Colorado River Streamflow Below the RMPF 

Parameter Statistic 

Historical Flows LCRA-SAWS Projected Flows

Existing 

Units 

Operation 

Scenario 

Existing and 

Proposed Units 

Operation 

Scenario 

Existing 

Units 

Operation 

Scenario 

Existing and 

Proposed Units 

Operation 

Scenario 

Streamflow 

below RMPF 

(cfs) 

10th percentile 253 253 101 101 

50th percentile (median) 814 795 559 509 

90th percentile 5629 5610 3948 3880 

The statistical distribution of streamflow in the Colorado River below the RMPF showed a slight 

change when the proposed units were added. For both the historical and the projected 

streamflow scenarios, the maximum change in streamflow due to the incremental water use for 

the proposed units occurred for the median discharge; the median discharge reduced by 

2 percent for historical and 9 percent for the projected discharge scenario from the base case. 

The 10th percentile streamflow in the Colorado River below the RMPF did not show any change 

for both streamflow scenarios because the 10th percentile streamflow for both scenarios are 

less than 300 cfs, which, under the LCRA contract, is the minimum streamflow in the river 

before STPNOC can withdraw any makeup water for the MCR. The review team concludes that 

because of this condition, streamflows less than 300 cfs would be unaffected by the operation of 

the proposed units. The 90th percentile streamflow in the Colorado River below the RMPF 

showed less than one-half percent reduction from the base case for the historical streamflow 

scenario and the corresponding reduction for the projected streamflow scenario was 2 percent 

from the base case. The relatively small change in the 90th percentile flow occurred because 

the demand for makeup water for the MCR is a small fraction of these flows. The review team 

concludes that if the required MCR makeup water is withdrawn from the river during periods of 

high flows, the relative decline in Colorado River streamflow would be minimized. 

The review team reviewed STPNOC’s water budget and water quality calculations. The 

conditions used by STPNOC in the MCR water budget and water quality simulations did not 

prefer any season or streamflow conditions in the Colorado River to commence discharge to the 

river. If, on any given day, makeup water to the MCR and discharge from the MCR were 

permitted by the rules specified by LCRA and TCEQ, respectively, the reservoir was operated in 

the simulations to manage water quality parameters within the MCR. Over the simulation time 

period using historical flows, the MCR discharged slightly less than 9 percent of the days for the 
 Operational Impacts at the Proposed Site 

February 2011 5-11 NUREG-1937 

existing units’ operation scenario and 9 percent of the days for the existing and proposed units’ 

operation scenario. For the simulations using projected streamflow, the MCR discharged 

7 percent and 6 percent of the days for the existing units’ operation scenario and the existing 

and proposed units’ operation scenario, respectively. Because the MCR discharge occurred 

approximately 9 percent of the time for the four-unit operation scenario described above, the 

review team concludes, based on the results of the simulation model, that on an average, over 

an extended period, discharge from the MCR during the operation of existing and proposed 

units could occur as frequently as once in 11 days (9 percent of the time). 

Under the historical flow scenario and operation of the existing units, the median streamflow for 

the Colorado River below the RMPF is 814 cfs. The corresponding median streamflow of the 

Colorado River below the RMPF when proposed Units 3 and 4 would also be in operation would 

be 795 cfs. The current TPDES permit allows STPNOC to discharge from the MCR only when 

the flow in the Colorado River is 800 cfs or greater. Assuming that the same TPDES conditions 

to apply to proposed Units 3 and 4, the review team determined that during operation of all four 

units at the STP site, discharges from the MCR would only occur when flow in the Colorado 

River slightly exceeds the expected median flow. Because the discharges from the MCR would 

be allowed at 800 cfs, the review team also determined that over a sufficiently long time period, 

STPNOC could discharge slightly less than 1 in 2 days. Because STPNOC would need to 

discharge once in 11 days, the review team concludes that sufficient flexibility exists to allow 

operations of all four units at the STP site. 

Because the addition of Units 3 and 4 would result in slight decreases in Colorado River 

streamflow below the RMPF, slight changes in the frequency of discharge to the Colorado 

River, and sufficient flexibility for operations of proposed Units 3 and 4, the review team 

determined that the impact of surface-water use by the proposed units would be SMALL and no 

mitigation is warranted. 

5.2.2.2 Groundwater-Use Impacts 

STPNOC currently holds a groundwater use permit to withdraw from the Deep Aquifer an 

average of approximately 3000 ac-ft/yr (1860 gpm) (CPGCD 2008). The permit allows 

STPNOC to withdraw up to 9000 ac-ft of water over an approximately 3-year period. 

Fluctuating use levels within the 3-year period is allowed; however, the total permit level of 

9000 ac-ft is absolute. STPNOC plans to use groundwater as the source for makeup water for 

proposed Units 3 and 4 UHS, service water for the power plants, fire protection systems, and 

water for potable and sanitary systems. As discussed in Section 3.4.2, STPNOC estimates that 

the two proposed units would require approximately 975 gpm of groundwater during normal 

operation and 3434 gpm during short-term peak demand periods (STPNOC 2010a). STPNOC 

would use groundwater up to its current permitted limit to support both existing and proposed 

units. Based on a monthly analysis of groundwater demand, STPNOC has concluded that site 

groundwater demand during construction, preconstruction, initial testing, and operation of Units 
Operational Impacts at the Proposed Site 

NUREG-1937 5-12 February 2011 

3 and 4 would be met by the existing groundwater use permit level of approximately 

3000 ac-ft/yr. However, short-term peak site groundwater demand would be met through use of 

a maintained groundwater storage capacity. In the unlikely event of unanticipated peak site 

water demands, the MCR and Colorado River remain as alternative sources. 

The available groundwater resource is estimated at the county level by the CPGCD (Turner 

Collie & Braden 2004), which is responsible for issuing permits to drill and operate groundwater 

wells in Matagorda County. The CPGCD adopted a groundwater availability value of 

49,221 ac-ft/yr (30,520 gpm) (Turner Collie & Braden 2004). This value also appears in 

Region K planning documents by the Lower Colorado Regional Water Planning Group 

(LCRWPG) (LCRWPG 2006), and is part of the regional water resource estimates appearing in 

the State water plan (TWDB 2007). The CPGCD estimates the groundwater supply consistent 

with the existing water supply infrastructure is a constant 35,785 ac-ft/yr (22,189 gpm) through 

2050 and that average usage for the period 1980 through 2000 is 30,233 ac-ft/yr (18,746 gpm) 

(Turner Collie & Braden 2004). The LCRWPG (2006) projected that groundwater resource 

development strategies could make an additional 29,546 ac-ft/yr available by 2060. This added 

to the groundwater supply of 35,785 ac-ft/yr would be a groundwater resource of approximately 

63,500 ac-ft/yr (39,400 gpm) in 2060. 

To satisfy increased groundwater demand at the STP site related to operation of proposed 

Units 3 and 4, STPNOC would use the currently unused portion of the groundwater permit limit, 

where the permit limit is approximately 3000 ac-ft/yr (1860 gpm). STPNOC currently uses an 

average of 798 gpm of groundwater for the operation of existing STP Units 1 and 2 leaving an 

average of 1062 gpm available for the operation of Units 3 and 4 (STPNOC 2010a). This 

increase in groundwater use is equivalent to 4.8 percent of the current groundwater supply and 

represents 5.7 percent of current groundwater use in Matagorda County. 

Potential offsite impact on the groundwater resource during the operation of the two proposed 

STP units is the result of an annual average normal operation groundwater use of 1062 gpm 

(1713 ac-ft/yr). This is the maximum usage allowed under the groundwater use permit held by 

STPNOC. A potential offsite impact evaluated by the review team is the estimated decline in 

hydraulic head in the Deep Aquifer within the Chicot Aquifer using a conservative analysis 

based on withdrawal from an onsite well pumped at a representative value (i.e., 500 gpm). 

Drawdown is evaluated at the property line and at a point 2500 ft from the STP well because 

that is the minimum distance allowed by the CPGCD between groundwater production wells not 

owned by the same permit holder (CPGCD 2009). The well location and minimum depth to top 

of screen is assumed to meet CPGCD requirements of a minimum setback of 100 ft from the 

property line with a screen beginning no higher than 200 ft below ground surface (BGS). The 

review team assumed the production well is pumped at 500 gpm and is screened over an 

approximate 500-ft interval with the well completed at approximately 700 ft BGS. This is typical 

of existing and proposed production wells at the STP site (STPNOC 2010a). 
 Operational Impacts at the Proposed Site 

February 2011 5-13 NUREG-1937 

The hydraulic head in the Deep Aquifer was between 40 and 60 ft below MSL in the vicinity of 

the STP site during site characterization activities for the proposed units (i.e., 2006) (STPNOC 

2010a). Using hydraulic properties typical of the STP site (see Table 2-3), the drawdown 

caused by a production well 100 ft from the site property line pumped continuously for 40 years 

at the expected rate of 500 gpm would be approximately 33 ft. Thus, for a single well being 

pumped, and adjacent wells idle, the hydraulic head in the vicinity of the property line would be 

approximately 93 ft below MSL. The top of the Deep Aquifer lies between 250 and 300 ft BGS, 

the land surface is approximately 27 ft above MSL, and the top of the aquifer is at the elevation 

223 ft below MSL. Therefore, the aquifer remains confined with a confining pressure of 

approximately 130 ft. 

At a distance of 2500 ft from the STP production well, the nearest allowed well location per 

CPGCD rule for wells not owned by the same permit holder (CPGCD 2009), the drawdown 

would be approximately 21 ft based on the assumptions discussed above. The hydraulic head 

would be approximately 80 ft below MSL. Because of the rules of the CPGCD (CPGCD 2009), 

the location 2500 ft from an STP production well is assumed to be the closest location of an 

adjacent offsite well, and the estimated hydraulic head is indicative of the highest impact to 

adjacent landowners. At such a location, the aquifer remains confined with a confining pressure 

of approximately 143 ft. 

The review team’s calculated drawdown values are shown in Table 5-2 for both the 500-gpm 

pumping rate of a single well, and the overall 1062-gpm rate available under STPNOC’s 

groundwater use permit. Using a 500-gpm rate is consistent with current and proposed STP 

production well operation. The 1062-gpm pumping rate is included to show an absolute 

maximum impact; however, this is conservative because it is an estimate of drawdown 

assuming a single production well produces all the groundwater for proposed Units 3 and 4. 

A further conservatism is given by neglecting any recharge to the aquifer. Results of the 

1062-gpm case conservatively bound an estimate of adjacent well drawdown (i.e., 44.7 ft). This 

is equivalent to a piezometric level approximately 105 ft below MSL and a confining pressure on 

the Deep Aquifer of approximately 118 ft. 

Table 5-2. Drawdown at the STP Property Line (100 ft) and a Point 2500 ft from a 

Production Well 

Pumping Rate 

(gpm) 

Distance (ft) 

100 2500 

500 32.8 21.0 

1062 69.6 44.7 

time = 40 yr; transmissivity = 31,379 gpd/ft (geometric mean); coefficient of 

storage = 0.00022; drawdown calculated using the Theis formula 
Operational Impacts at the Proposed Site 

NUREG-1937 5-14 February 2011 

The Deep Aquifer, which would be the source of groundwater during operation of the proposed 

new units, has been affected by long-term regional irrigation demand. Land surface subsidence 

since 1900 is estimated to be less than 1 ft over most of Matagorda County (LCRA 2007a), and 

subsidence in excess of 1 ft in the northwest corner of the County is attributed to groundwater 

production associated with gas/petroleum exploration and sulfur mining (LCRA 2007a). 

STPNOC currently uses five production wells to produce groundwater in support of STP Units 1 

and 2, and may drill and operate one or more additional well to decrease the pumping rates at 

each well and reduce the drawdown impact (STPNOC 2010a). The wellfield design helps to 

minimize the potential for subsidence while producing the necessary groundwater. They are 

placed and operated so that no sustained pumping occurs within 4000 ft of the existing or 

proposed units, and the CPGCD requires that wells not owned by the same permit holder be no 

closer than 2500 ft apart. The highest rated existing wells can pump 500 gpm, and it is 

assumed that new wells would produce 500 gpm (STPNOC 2010a). Thus, assuming a 

reasonable well spacing between wells owned by the same permit holder, the review team 

concludes that the stress on the Deep Aquifer would be distributed spatially across the STP site, 

minimizing local drawdown and the potential for subsidence. 

Since operation of proposed Units 3 and 4 would use an estimated maximum 1062 gpm 

(1713 ac-ft/yr) of Deep Aquifer groundwater, that quantity of groundwater would no longer move 

downgradient and discharge into Matagorda Bay and the Colorado River estuary 

(STPNOC 2010a). Thus, one impact of operating the proposed units is a reduction of up to 

1062 gpm (1713 ac-ft/yr) in the Deep Aquifer flow into the bay and estuarine environment. The 

reduction equates to 2.37 cfs and compares to the average minimum monthly flow of the 

Colorado River near Bay City of 327 cfs (month of August), the average maximum monthly flow 

of the Colorado River near Bay City of 14,123 cfs (month of June), and the minimum Matagorda 

Bay monthly target inflow of 1008 cfs for the month of August (STPNOC 2010a). 

Based on the following considerations: 

• a groundwater resource sufficient to sustain the projected STP site groundwater use, 

projected drawdown during normal operation, and the presence of sufficient confining head 

to maintain a confined aquifer, 

• production wells designed to minimize the potential for subsidence, and 

• relatively small depletion of discharge to Matagorda Bay and the estuarine environment, 

the review team concludes that groundwater use impacts to the groundwater resource from 

operation of the proposed Units 3 and 4 would be SMALL, and mitigation is not warranted. 
 Operational Impacts at the Proposed Site 

February 2011 5-15 NUREG-1937 

5.2.3 Water-Quality Impacts 

This section discusses the impacts to the quality of water resources from the operation of 

proposed Units 3 and 4. Surface-water impacts include thermal, chemical, and radiological 

wastes, and physical changes in the Colorado River resulting from effluents discharged by the 

plant. 

5.2.3.1 Surface-Water Quality Impacts 

The only surface-water discharges during operations of proposed Units 3 and 4 would occur as 

(1) stormwater runoff to nearby sloughs, the Colorado River, and the West Branch of the 

Colorado River, (2) MCR discharge to the Colorado River, and (3) seepage from the MCR 

intercepted by the relief wells and discharged through the site drainage ditches to Little Robbins 

Slough and the Colorado River upstream of the RMPF. 

As stated at the beginning of this section, STPNOC would be required to obtain a multi-sector 

stormwater permit from the TCEQ. STPNOC would be required to develop and implement an 

SWPPP to control stormwater runoff to onsite and offsite water bodies as described in the 

previous paragraph. STPNOC’s existing SWPPP would be amended to include activities 

associated with the proposed new units (STPNOC 2010a). Implementation of best 

management practices (BMPs) as contained in the SWPPP would minimize stormwater runoff 

to onsite and offsite water bodies. 

During the operation of proposed Units 3 and 4, periodic maintenance dredging near the RMPF 

may be required on an as-needed basis to remove accumulated sediment (STPNOC 2010a). 

These activities would be conducted under a Corps permit. The review team determined that 

the impact to water quality of the Colorado River from these activities would be temporary and 

minimal because BMPs would be employed. 

During the operation of proposed Units 3 and 4, the MCR would receive effluents that consist of 

the following: (1) UHS cooling tower blowdown, (2) treated sanitary waste, (3) treated liquid 

radwaste, (4) wastewater retention basin discharge, and (5) startup/flush pond discharge. The 

last effluent discharge stream, the startup/flush pond discharge, is an intermittent stream, which 

is treated onsite before it would be discharged to the MCR. Potable and sanitary wastewater 

would be treated by the sanitary waste system before being discharged to the MCR. The 

wastewater retention basin would receive effluents from low-volume waste streams. 

The only discharges to publicly accessible surface waters during the operations of Units 3 and 4 

would occur as the MCR discharge into the Colorado River and from the site drainage ditch, 

which discharges to Little Robbins Slough, to the Colorado River upstream of the RMPF, and to 

the West Branch of the Colorado River. The MCR gains water from precipitation and makeup 

water pumped from the Colorado River. The MCR loses water by natural and induced 

evaporation, by seepage to groundwater, and by periodic discharge to the Colorado River. The 
Operational Impacts at the Proposed Site 

NUREG-1937 5-16 February 2011 

concentration of dissolved materials contained in the water of the MCR would increase as plant 

effluent discharges to and evaporation from the MCR continues. The water quality in the MCR 

is managed by diluting it with makeup water from the Colorado River and by discharging to the 

Colorado River. The makeup flow rate is regulated under the LCRA permit. The flow rate and 

the concentrations of effluents in the MCR discharge would be regulated by the TPDES permit. 

In supplemental information provided to the NRC, STPNOC described the operating policy of 

the MCR (STPNOC 2009b). STPNOC would discharge when the specific conductivity of the 

water in the MCR exceeds 3000 μS/cm and when other concurrent requirements specified in 

the LCRA water contract are met (STPNOC 2009c). Makeup water would be pumped from the 

Colorado River into the MCR consistent with the provisions of the LCRA contract. The MCR 

discharge would cease when the conductivity of the water in the MCR falls to 2100 μS/cm and 

when other concurrent requirements specified in the LCRA water contract are met (STPNOC 

2009c). Discharge from the MCR could also occur during large rainfall events when the MCR 

water surface elevation exceeds the spillway crest elevation. 

Table 5-3 below shows the summary statistics of water quality parameters obtained from the 

STPNOC’s MCR water budget and water quality model simulations. The MCR water budget 

and water quality model is described in Section 5.2.2.1. The review team’s independent 

assessment of STPNOC’s water budget and water quality model is also described in 

Section 5.2.2.1. 

Table 5-3. Summary Statistics of Simulated Water Temperature and Total Dissolved Solids of 

MCR Discharge 

Parameter Statistic 

Historical Flows 

LCRA-SAWS 

Projected Flows 

Existing 

Units 

Operation 

Scenario 

Existing and 

Proposed 

Units 

Operation 

Scenario 

Existing 

Units 

Operation 

Scenario 

Existing and 

Proposed 

Units 

Operation 

Scenario 

Water 

temperature of 

MCR discharge 

(°F) 

10th percentile 64.1 69.4 64.1 70.1 

50th percentile (median) 75.2 75.6 73.9 76.0 

90th percentile 90.5 88.0 86.9 87.6 

Total dissolved 

solids in MCR 

discharge (mg/L) 

10th percentile 1934 2313 1950 2823 

50th percentile (median) 2048 2844 2186 3548 

90th percentile 2599 3673 2644 4550 

Source: STPNOC 2009b 
 Operational Impacts at the Proposed Site 

February 2011 5-17 NUREG-1937 

The statistical distribution of water temperature of the MCR discharge showed increases of 

5.3°F in the 10th percentile and a decrease of 1.5°F in the 90th percentile for the hypothetical 

simulations that used historical streamflow; there was only a slight increase in the median. For 

the hypothetical simulations that used LCRA-SAWS projected streamflow, the temperatures of 

MCR discharge increased 6°F for the 10th percentile, 2.1°F for the median, and 0.7°F for the 

90th percentile. 

The statistical distribution of simulated total dissolved solids within the MCR showed increases 

of approximately 20, 39, and 41 percent in the 10th, 50th, and 90th percentiles for hypothetical 

simulations using historical discharges, respectively. The statistical distribution showed 

corresponding increases of approximately 44, 62, and 72 percent for the hypothetical 

simulations that used the LCRA-SAWS projected streamflow. 

The maximum duration of continuous discharge from the MCR to the Colorado River for the 

existing units’ operation scenario using historical flows was 88 days. The corresponding 

duration of continuous discharge for the existing and proposed units’ operation scenario was 

73 days. The maximum duration of continuous discharge from the MCR to the Colorado River 

for the existing units’ operation scenario using projected flows was 74 days. The corresponding 

duration of continuous discharge for the existing and proposed units’ operation scenario was 

37 days. 

STPNOC performed a Cornell Mixing Zone Expert System (CORMIX) analysis to estimate the 

extent of the MCR discharge plume in the Colorado River. The discharge structure consists of 

seven ports located near the bottom of the river, each of which is capable of a maximum 

discharge of 44 cfs, for a total maximum MCR discharge of 308 cfs. STPNOC used a bounding 

approach to estimate the impacts of the MCR discharge on the Colorado River, assuming that 

all ports would discharge at their maximum capacity. The review team determined that this 

assumption is conservative because it would result in maximizing the size of the plume. 

Currently, the TPDES permit disallows any discharge from the MCR to the Colorado River when 

the flow of the river adjacent to the STP site is less than or equal to 800 cfs, restricts the 

discharge from the MCR to the Colorado River to less than or equal to 12.5 percent of the flow 

in the river (see Section 2.3.3.1), and restricts the discharge temperature to less than or equal to 

95°F. STPNOC also assumed that during this discharge, the difference in temperatures 

between the MCR waters and the waters of the Colorado River would be 20.4°F, which was the 

maximum monthly difference in the long-term hypothetical simulations of MCR water budget 

and quality. The review team determined that this assumption is also conservative and would 

maximize the size of the plume. The TPDES permit requirements would allow an MCR 

discharge of 308 cfs at a minimum Colorado River streamflow of 2464 cfs. 

Discharge and salinity data collected by STPNOC during September 2007 to May 2008 

indicated that a salinity wedge intrusion occurred near the STP site when the mean monthly flow 

in the Colorado River was less than 1800 cfs (STPNOC 2008c). The review team determined 
Operational Impacts at the Proposed Site 

NUREG-1937 5-18 February 2011 

that the salinity wedge, observed near the RMPF during tidal conditions, would be very small, if 

at all present, during flows in the Colorado River at 2464 cfs. 

STPNOC's CORMIX analysis estimated a plume defined by the 5°F isotherm. The plume was 

predicted to be attached to the river bottom for approximately 120 ft downstream of the 

discharge ports, and within this short distance the plume extended less than one quarter of the 

width of the river. The plume was predicted to quickly rise to the river surface further 

downstream, occupying the full width of the river cross section approximately 1060 ft 

downstream of the ports and continuing for an additional 3340 ft. The plume extended 

approximately 4400 ft downstream from the ports. 

Before the plume traveled 300 ft downstream of the discharge ports, the lower boundary of the 

plume migrated upward, only existing in the upper half of the river cross section. The deeper 

portion of the river cross section remained close to ambient temperatures. 

The review team also independently performed additional CORMIX simulations where (1) the 

discharges from the ports were reduced to half of their capacity and the streamflow in the 

Colorado River was increased to 4000 cfs and (2) the discharges from the port were allowed to 

occur at full capacity and the streamflow in the river was increased to 10,000 cfs. During these 

simulations the temperature difference between the river and the MCR discharge was kept the 

same. The results obtained by the review team showed that the MCR discharge plume was 

very small in the river. The total length and maximum width of the discharge plume were 

115 and 26 ft, respectively. The review team determined that the maximum width of the MCR 

discharge plume in the river would be less than 10 percent of the river width. Therefore, the 

review team concludes that there is considerable flexibility available in the way the MCR 

discharge could be operated to minimize the size of the plume in the river. 

The review team also performed a simple heat balance calculation to check whether the results 

of CORMIX simulation are reasonable. Assuming the complete mixing of discharge with 

ambient water, the temperature excess would be about 2.3°F which is below the mixing zone 

criteria. In the case of surface floating plume with laterally mixed across the whole river 

channel, the plume thickness corresponding to the mixing zone criteria (5°F) is approximately 

estimated less than a half of water depth. These estimations are consistent with the CORMIX 

model results. 

The review team determined, therefore, that the 5°F isotherm plume, resulting from a bounding 

scenario of MCR discharge, would not completely block the river cross section. The plume 

resulting from the MCR discharge during the operation of existing and proposed units could last 

for a relatively extended duration, up to nearly 75 days, and could also occur relatively 

frequently, once every 11 days. The review team determined, based on a review of the current 

TPDES permit conditions, that the minimum dilution in the Colorado River would be a factor of 

8. Any chemical or radiological contaminants present in the MCR waters would be diluted a 
 Operational Impacts at the Proposed Site 

February 2011 5-19 NUREG-1937 

minimum of 8 times and would, following the cessation of MCR discharge, be quickly 

transported downstream to the Matagorda Bay where they would be diluted even further. The 

review team determined, therefore, that the impact on water quality of the Colorado River from 

the operation of Units 3 and 4 would be SMALL and no mitigation is warranted. 

5.2.3.2 Groundwater-Quality Impacts 

Operation of proposed Units 3 and 4 would involve seepage from the MCR into the Upper 

Shallow Aquifer; however, operation should not involve any other intentional discharges to the 

aquifer system that underlies the STP site. Spills that might impact the quality of the Shallow 

Aquifer would be prevented and mitigated by BMPs. Except where excavation removes it, the 

Shallow Aquifer is protected from spills on the land surface by a 10- to 30-ft thick low 

conductivity confining zone. Groundwater flow in the Upper Shallow Aquifer away from the 

proposed units would be to the southeast or the southwest (see Section 4.2.3.2) and toward the 

STP site property boundary. Representative travel times in the Upper Shallow Aquifer from 

proposed Unit 3 to the southeast site property line would be approximately 154 years (STPNOC 

2010c) and from proposed Unit 4 to the southwest property line would be approximately 

330 years. A representative travel time in the Lower Shallow Aquifer from the proposed units to 

the southeast property line would be approximately 125 years. The review team concludes that 

these travel times should allow for cleanup and remediation to occur. 

A potential offsite impact on the quality of the groundwater resource during operation of the 

proposed Units 3 and 4 is saltwater intrusion or encroachment resulting from pumping at the 

annual average normal operation rate allowable under the existing STPNOC groundwater use 

permit (i.e., 1062 gpm, 1713 ac-ft/yr). Production wells with depths ranging from 600 to 700 ft 

BGS and up to 500 ft of screen at the STP site are completed in the upper portion of the Deep 

Aquifer. The wells have design pumping capacities between 200 and 500 gpm. LCRA (2007b) 

evaluated the design of wells and their production rate with regard to saltwater intrusion or 

encroachment (see Section 2.3.3.2). Based on the LCRA study findings, the review team 

concludes the existing and proposed well designs at the STP site, coupled with a reasonable 

spacing between wells owned by the same permit holder, would minimize the drawdown and 

also minimize the potential for lateral or vertical saltwater intrusion. 

Seepage from the MCR enters the Upper Shallow Aquifer. The relief well system, 

(i.e., 770 wells that surround the MCR), is designed in part to intercept the majority of the 

seepage from the MCR into the Upper Shallow Aquifer. The updated FSAR (UFSAR) 

(STPNOC 2008g) for STP Units 1 and 2 estimated for an MCR at 49 ft above MSL pool 

elevation that total seepage from the MCR is 3530 gpm (5700 ac-ft/yr), and that approximately 

68 percent of this (2400 gpm, 3850 ac-ft/yr) is intercepted by the relief wells and discharged 

under the TDPES permit (TCEQ 2005). As stated in Section 2.3.1.2, recent simulations of the 

Shallow Aquifer underlying the STP site have indicated that the relief wells and sand drains 

intercept approximately 50 percent of the total seepage from the MCR (STPNOC 2010b). 
Operational Impacts at the Proposed Site 

NUREG-1937 5-20 February 2011 

During January through April of 2003, while the MCR was at elevation 47 ft above MSL, 

measurements were made of the water level in a series of piezometers located 260 ft landward 

from the embankment centerline (STPNOC 2010c). These piezometers showed a head drop 

from MCR to piezometer varying from approximately 19.5 to 33.9 ft along the western, northern, 

and eastern embankments. Along the southern embankment the head drop varied from 

approximately 29.7 to 35.0 ft. The pool elevation change of the MCR from a maximum of 47 ft 

above MSL to 49 ft above MSL to support proposed Units 3 and 4 is expected to cause an 

increase in the seepage of MCR water into the Upper Shallow aquifer. Based on the above 

information, the review team determined that the two foot rise of MCR maximum level would 

increase the head drop of the hydraulic gradient by no more than 2 ft over the prior condition 

and therefore, the increase in seepage from the MCR into the Upper Shallow aquifer is bounded 

by a range of 10.3 to 5.9 percent along the western, northern and eastern embankment, and 6.7 

to 5.7 percent along the southern embankment. 

Regarding radioactive contaminants in the MCR and impacts related to seepage into the 

underlying aquifer, see Sections 5.9.2.1, 5.9.5.1, and 5.9.6. 

Regarding nonradioactive contaminants in the MCR, total dissolved solids (TDS) is an indicator 

described in Sections 2.3.3.1, 2.3.3.2, and 5.2.3.1. It is anticipated by the review team that 

seepage from the MCR to the Upper Shallow Aquifer would initially have the same TDS 

concentration of the MCR. STPNOC’s estimate of the median TDS concentration in the MCR 

for operation of the existing units is approximately 2000 mg/L, and for both existing and 

proposed units it is approximately 3000 mg/L (see Section 5.2.3.1). The review team concludes 

that an increase in TDS levels of 1000 mg/L in the MCR could result in a corresponding 

increase of 1000 mg/L in groundwater concentrations downgradient of the MCR. This is 

conservative because it does not consider dispersion within the groundwater system, which 

would likely reduce this concentration increment. 

Locally, groundwater from the Shallow Aquifer is described as slightly saline because of TDS 

concentrations above 1000 mg/L (i.e., slightly saline waters have TDS between 1000 mg/L and 

3000 mg/L). Onsite wells completed in the Shallow Aquifer have an average TDS concentration 

of 1200 mg/L (STPNOC 2010a). Accordingly, the Shallow Aquifer is used locally to water 

livestock, and it is not a fresh water supply. The review team concludes that with an increase of 

1000 mg/L, the groundwater TDS concentration would remain in the range associated with 

slightly saline waters. If groundwater in the Upper Shallow Aquifer had the TDS concentration 

of the MCR water, it would be approximately 3000 mg/L and at the upper end of the slightly 

saline range. The potential future TDS level is consistent with the existing groundwater quality 

and its use as a source of water for livestock. Any impacts from this groundwater would be local 

because groundwater plumes originating from the MCR would be local to the STP site and the 

region immediately downgradient of the site to the Colorado River. 
 Operational Impacts at the Proposed Site 

February 2011 5-21 NUREG-1937 

From the information available on TDS concentrations in the MCR and in the Shallow Aquifer, 

the review team concludes that TDS is an indicator of MCR seepage water quality and that 

while the concentration of TDS is expected to increase, the incremental increase would 

minimally change the groundwater resource. Based on the consideration of the potential impact 

from spills, saltwater intrusion, and seepage from the MCR to the underlying aquifer, the review 

team concludes that groundwater-quality impacts would be SMALL and mitigation is not 

warranted. 

5.2.4 Water Monitoring 

Currently, as part of the operations of existing STP Units 1 and 2, STPNOC conducts surface 

water monitoring as required by the current TPDES permit. The surface water is monitored at 

six locations. Flow volume on a daily basis is monitored at five internal outfalls within the MCR 

(Figure 2-17) and reported to the TCEQ every month. 

Outfall 001 is associated with the MCR blowdown discharge pipe. All other monitoring locations 

are associated with effluent streams that discharge into the MCR. Flow at Outfall 001 is 

measured continuously and on a daily basis when a discharge is made to the Colorado River. 

Flow at all other monitoring locations is measured daily. 

Under the current water rights permit, STPNOC monitors makeup water diverted from the 

Colorado River and water consumed on a monthly basis and reports it to TCEQ annually. The 

annual volume of diverted water is also reported to TWDB. 

Currently, STPNOC monitors stormwater at eight locations (Figure 2-18) under its existing 

SWPPP. The discharge during precipitation events is measured at these locations. 

Hydrological monitoring during the operations of proposed Units 3 and 4 would be required by 

TCEQ in the modified TPDES permit and in the new or amended SWPPP. The requirements 

for hydrological monitoring for proposed Units 3 and 4 are expected to be similar to the current 

requirements for existing STP Units 1 and 2. 

Currently, STPNOC monitors surface waters for chemicals under the existing TPDES and 

stormwater permits. Outfall 001 is sampled weekly for total residual chlorine when a discharge 

occurs from the MCR. Outfall 005 is sampled weekly for iron and copper when metal cleaning 

waste is discharged into the MCR. Outfalls 101 and 201 are sampled weekly for total 

suspended solids and for oil and grease. Outfalls 401 and 601 are sampled weekly for 

biochemical oxygen demand and for total suspended solids. Currently, STPNOC monitors 

stormwater outfalls A, E, F, and G for iron and total suspended solids during precipitation 

events. 

Chemical monitoring during the operations of proposed Units 3 and 4 at STP would be required 

by TCEQ in the modified TPDES permit and in the new SWPPP. The requirements for 
Operational Impacts at the Proposed Site 

NUREG-1937 5-22 February 2011 

chemical monitoring for the two new proposed units are expected to be similar to the current 

requirements for existing STP Units 1 and 2. 

Currently, STPNOC continuously monitors temperature of the discharge from the MCR at 

Outfall 001 when blowdown is performed as required by the existing TPDES permit. Monitoring 

requirements would be addressed by the modified TPDES permit after the addition of Units 

3 and 4. These requirements are expected to be similar to those for existing STP Units 1 and 2. 

STPNOC anticipates that groundwater monitoring required during operation of Units 3 and 4 

would be similar to existing reporting requirements for STP Units 1 and 2 (STPNOC 2010a) and 

designed and implemented accordingly. However, STPNOC acknowledged that those 

requirements are changing in response to the Nuclear Energy Institute’s (NEI’s) program to 

collect groundwater data at commercial nuclear plants (STPNOC 2010a). Once the project is 

complete and the sediment profile has been allowed to rewet, STPNOC has committed to 

conduct an evaluation of groundwater level with the objective of determining whether 

groundwater level monitoring should continue to ensure that the maximum groundwater level 

beneath safety-related structures of Units 3 and 4 is below the site characteristic for maximum 

groundwater level (STPNOC 2008e). 

5.3 Ecological Impacts 

This section describes the potential impacts to ecological resources from operation of proposed 

Units 3 and 4 at the STP site, transmission line operation, and transmission line corridor 

maintenance. The impacts are discussed for terrestrial ecosystems and aquatic ecosystems, 

including threatened and endangered species. Evaluation of potential impacts to terrestrial and 

aquatic biota from radiological sources is discussed in Section 5.9 

5.3.1 Terrestrial and Wetland Impacts 

Impacts on terrestrial communities and species that could result from operation of the proposed 

units are generally related to cooling system operations or transmission line operations. 

Operation of the circulating water cooling system, for which the MCR is the normal heat sink, 

would have negligible impact on terrestrial resources, and is discussed in this section only as 

relative to shoreline habitat. Operation of the UHS cooling system can result in deposition of 

dissolved solids; increased local fogging, precipitation, or icing; increased noise levels; and a 

greater risk of collision mortality to avian species; and shoreline alterations of the source 

waterbody. Impacts from the operation and maintenance of the transmission system that may 

affect terrestrial species include collision mortality and electrocution, electromagnetic fields 

(EMFs), and the maintenance of vegetation within transmission line corridors. 
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February 2011 5-23 NUREG-1937 

5.3.1.1 Terrestrial Resources – Site and Vicinity 

Impacts of operation of Units 3 and 4 on the STP site and vicinity are associated with the 

increase in the operating level in the MCR and operation of two proposed UHS mechanical draft 

cooling towers. As described in Chapter 3, the UHS includes a closed-loop system that 

dissipates gained heat to the atmosphere via mechanical draft cooling towers. In this system, 

the heat would be transferred to the atmosphere in the form of water vapor and drift. Vapor 

plumes and drift may affect vegetation such as crops, ornamental vegetation, and native plant 

communities. In addition, bird collisions and noise-related impacts are possible with mechanical 

draft cooling towers and other facility structures. 

Impacts of Cooling Tower Operations 

Two mechanical draft cooling towers are contiguous with the UHS reservoir and structure and 

would be positioned immediately south of Units 3 and 4 in an industrial area. Makeup water to 

the UHS cooling towers would be supplied from site groundwater wells, with backup from the 

MCR. Through the process of evaporation, the total dissolved solid concentration in the cooling 

water increases, and a small percentage of the water is released into the atmosphere as fine 

droplets containing elevated levels of TDS that can be deposited on nearby vegetation. 

Maximum UHS blowdown and make up rates are based on maintaining three cycles of 

concentration in the cooling tower, which means the TDS in the makeup water would be 

concentrated approximately three times before being released. Cooling tower water losses from 

drift are minor in comparison to evaporation and blowdown discharge losses, and the maximum 

drift rate reported by STPNOC is estimated to be 10 gpm when both units are operating 

(STPNOC 2010a). 

Depending on the make-up source water body, the TDS concentration in the drift can contain 

high levels of salts that under certain conditions and for certain species can be damaging. 

Vegetation stress can be caused from drift with high levels of TDS deposition, either directly by 

deposition onto foliage or indirectly from the accumulation in the soils. Vegetation adjacent to 

the cooling towers includes relatively open habitats: mowed areas and other areas dominated 

by mixed grasses, dewberry (Rubus spp.), and sea myrtle (Baccharis halimifolia). 

A deposition rate of 8.9 lb/ac/mo during the growing season is considered a threshold value for 

causing damage to leaves of a variety of species (NRC 2000). The STPNOC analysis indicated 

that the annual salt deposition rate from cooling tower drift could be as high as 98 lb/ac/mo near 

the towers, decreasing to less than 8.9 lb/ac/mo at about 0.3 mi, and less than 1 lb/ac/mo 

beyond about 0.8 mi. The maximum deposition rates occur during the summer. Most of the 

area with a deposition rate exceeding 8.9 lb/ac/mo is within the protected area to the north of 

the cooling towers, and between the protected area and the MCR. Regardless of the plume 

direction, maximum deposition would occur on the STP site (STPNOC 2010a). Although the 

maximum deposition within 0.3 mi of the cooling towers estimated for the proposed Units 3 
Operational Impacts at the Proposed Site 

NUREG-1937 5-24 February 2011 

and 4 is greater than the threshold value for causing damage to leaves, the maximum salt 

deposition would occur primarily in areas that would be occupied by existing and planned 

facilities and maintained/mowed vegetation. Thus, the potential impacts to vegetation and 

surrounding habitat would be limited to a relatively small area within 0.3 mi of the cooling tower, 

and impacts would be expected to be minimal. 

Although STPNOC leases a portion of the site for cattle grazing, these lands are located more 

than 2000 ft from the cooling towers and would not be expected to receive significant salt 

deposition from plume drift. The impact of drift on crops, ornamental vegetation, and native 

plants was evaluated for existing nuclear power plants in NUREG-1437, Generic Environmental 

Impact Statement for License Renewal of Nuclear Plants (GEIS), and was found to be of minor 

significance (NRC 1996a, 1999).(a) This determination also included existing nuclear power 

plants with more than one cooling tower. 

Due to the local climate and topography, fogging and associated icing are not expected from the 

operation of the two mechanical draft cooling towers at the STP site and, therefore, would not 

cause any impacts to habitat or wildlife (STPNOC 2010a). Thus, the potential impact on crops, 

ornamental vegetation, and native plants from the operation of UHS cooling towers for the 

proposed new units would be minimal, and mitigation would not be warranted. 

Bird Collisions with Cooling Towers and Structures 

The potential exists for avian mortality due to collision with proposed nuclear power plant 

structures and could pose a threat to those species in decline and to threatened or endangered 

species. The elevation of the tallest structure associated with the new units would be 

approximately 249 ft above MSL, which is similar to the heights of the existing reactor buildings 

on the STP site. The two mechanical draft cooling towers would reach a height of 

approximately 150 ft above MSL—or 119 ft above grade (STPNOC 2010a). Although the STP 

site lies at the terminus of the Central Migratory Flyway, no bird kills have been reported 

associated with the existing buildings on the STP site. Data available for communication towers 

indicate that tall towers greater than 1000 ft in height pose the greatest collision risk for birds 

(Manville 2005). Published accounts of bird strikes and kills at shorter towers are limited but are 

assumed to occur less frequently. 

The NRC has previously concluded that avian collisions are unlikely to pose a biologically 

significant source of mortality because only a small fraction of total bird mortality has been 

attributed to collision with nuclear power plant structures (NRC 1996a). Because the 

mechanical draft towers are relatively short and bird strikes and kills have not been observed in 

 

(a) NUREG-1437 was originally issued in 1996. Addendum 1 to NUREG-1437 was issued in 1999. 

Hereafter, all references to NUREG-1437 include NUREG-1437 and its Addendum 1. 
 Operational Impacts at the Proposed Site 

February 2011 5-25 NUREG-1937 

association with existing buildings of similar height at STP, the potential effects of bird collisions 

with the buildings and cooling towers associated with proposed Units 3 and 4 are assumed to 

be negligible. 

Noise Impacts of Operation 

The noise levels from cooling tower operation and diesel generators are anticipated to be 

65 decibels (dBA) at 50 ft (STPNOC 2010a). Noise levels from the combined operation of the 

two cooling towers are estimated to be approximately 51 dBA at 400 ft. A level of 51 dBA is well 

below the 60 to 65-dBA threshold at which birds and small mammals are startled or frightened 

(Golden et al. 1980). Thus, noise from operating mechanical draft cooling towers would not be 

likely to disturb wildlife in habitats away from the existing and planned facilities and would not 

affect wildlife beyond the STP site boundaries. Thus, the potential impact on wildlife posed by 

the incremental noise resulting from the operation of the two new mechanical draft cooling 

towers for Units 3 and 4 and other facilities at the STP site would be minimal, and mitigation 

would not be warranted. 

Shoreline Habitat Along MCR 

The normal operating level of the waters of the MCR would be raised approximately 2 ft (from 

47 ft above MSL to 49 ft above MSL) to provide additional water supply for cooling 

(STPNOC 2010a). The banks of the MCR are covered with a soil stabilizer and support little to 

no vegetation thus providing limited habitat adjacent to the existing water line. Although a 

number of colonial waterbirds nest on the Y dikes within the reservoir, raising the water level is 

not expected to affect existing nesting habitat or to significantly decrease the available nesting 

habitat for these birds. These birds tend to nest on the road bed positioned on the crown of the 

dike and areas immediately adjacent to this road. An increase in water level of 2 ft would not 

encroach on these nests. The MCR also is used by wintering waterfowl and other water birds 

for foraging and resting. As the water level is increased, some species that forage on benthos 

may temporarily loose the shallowest portion of the reservoir bottom as a forage area until 

sufficient time passes that mollusks and other invertebrates colonize the newly flooded portions 

of the shoreline (STPNOC 2010a). Assuming that the fish populations in the reservoir are not 

affected by the increased water level, piscivorous birds such as eagles, ospreys, pelicans, 

herons, and gulls that feed on fish near the surface of the reservoir and along its banks are not 

likely to be affected. Impacts to terrestrial species from raising the water level in the MCR are 

expected to be negligible. 

5.3.1.2 Terrestrial Resources – Transmission Lines 

Electric transmission systems have the potential to affect terrestrial ecological resources 

through right-of-way (ROW) maintenance, bird collisions with transmission lines, and EMFs. 

Existing 345-kV transmission lines and associated corridors would be used to transmit the 
Operational Impacts at the Proposed Site 

NUREG-1937 5-26 February 2011 

power generated from proposed Units 3 and 4. Four different entities are involved in 

maintaining the transmission corridors associated with existing STP Units 1 and 2. American 

Electric Power (AEP) Texas Central Company (TCC) maintains the transmission line corridor 

from STP to Hillje Substation and the corridor to Blessing, and from Hillje to White Point. AEP 

TCC surveys and controls the woody vegetation in the transmission corridors, as needed, every 

3 to 5 years to allow continuous and safe power transmission in accordance with their 

respective management plans. 

Existing management plans include procedures for removing rapidly growing trees and/or trees 

that might interfere with power transmission, pruning trees near transmission lines, and 

maintaining travel routes within the transmission line corridor. Manual and mechanical methods 

as well as herbicide application are used to remove trees encroaching on the power lines. 

Personnel involved in these maintenance activities are required to be trained and to hold Texas 

Department of Agriculture Commercial Pesticide Applicators licenses, and all herbicide use 

follows Federal, State, and local guidelines, and requires a Texas Department of Agriculture 

pesticide application permit. However, because much of the transmission corridors associated 

with the transmission of power from STP traverse primarily agricultural lands, the need for 

corridor maintenance is limited (STPNOC 2010a). 

Power generated from the proposed units would be transmitted through existing transmission 

corridors that are managed and monitored as described. No additional operational impacts 

associated with maintenance of transmission corridors are expected to occur as a result of 

operation of the two new units at STP. The impacts of transmission line corridor maintenance 

on wildlife and habitats, including floodplains and wetlands, were evaluated in the license 

renewal GEIS (NRC 1996a), and the impacts were found to be of small significance at operating 

nuclear power plants with associated transmission line corridors of variable widths (NRC 

1996a). STPNOC and the transmission service providers have procedures in place that 

minimize adverse impacts to wildlife and important habitats such as floodplains and wetlands. 

Therefore, the potential effects on terrestrial species and habitats from transmission line 

maintenance in existing transmission line corridors would be negligible and mitigation beyond 

the use of standard BMPs would not be warranted. 

Impacts of EMFs on Flora and Fauna 

EMFs are unlike other agents that have an adverse impact (e.g., toxic chemicals and ionizing 

radiation) in that dramatic acute effects cannot be demonstrated and long-term effects, if they 

exist, are subtle (NRC 1996a). As discussed in the GEIS for license renewal (NRC 1996a), a 

careful review of biological and physical studies of EMFs did not reveal consistent evidence 

linking harmful effects with field exposures. Operating power transmission lines in the United 

States produce EMFs of nonionizing radiation at 60 Hz, which is considered to be an extremely 

low frequency (ELF) EMF. All transmission lines connected to the proposed reactors would be 

345kV and there would be no change in line voltage; thus no increase in EMF would be 
 Operational Impacts at the Proposed Site 

February 2011 5-27 NUREG-1937 

expected to occur. The EMFs produced by operating transmission lines up to 1100 kV have not 

been reported to have any biologically or economically significant impact on plants, wildlife, 

agricultural crops, or livestock (Lee et al. 1989; Miller 1983). 

The conclusion presented in the GEIS for license renewal (NRC 1996a) was that the impacts of 

EMFs on terrestrial flora and fauna were of minimal significance at operating nuclear power 

plants, including transmission systems with variable numbers of transmission lines. Since 1997, 

more than a dozen studies have been published that looked at cancer in animals that were 

exposed to EMFs for all or most of their lives (Moulder 2009). These studies have found no 

evidence that EMFs cause any specific types of cancer in rats or mice (Moulder 2009). 

Therefore, the review team concludes that the EMF impact posed by the operation of the 

transmission lines associated with the STP site would be minimal and mitigation would not be 

warranted. 

Avian Collision and Electrocution 

Avian interactions with transmission lines and structures are species- and site-specific, and the 

potential impacts include bird injury or mortality through collision or electrocution. Procedures 

are in place to document transmission line mortalities of large birds, should they occur, and to 

deal with bird nests found in hazardous locations along the corridors (STPNOC 2010a), and 

operates under an Avian Protection Policy (AEP 2009; STPNOC 2009f). In addition, American 

Electric Power (AEP) responds to U.S. Fish and Wildlife (FWS) requests and requirements to 

install marking devices on some spans to prevent collisions (STPNOC 2009f). Bird 

electrocutions occur on utility poles and towers where birds use these structures for perching, 

roosting, and nesting. On structures where bird electrocution issues are identified, AEP applies 

protective devices to minimize bird electrocutions (STPNOC 2009f). 

The NRC’s analysis in the GEIS is that bird collisions with transmission lines are of small 

significance at operating nuclear power plants, including transmission corridors with variable 

numbers of transmission lines (NRC 1996a). Operation of the proposed units would not cause 

any additional impacts to avian species because there are no additional transmission corridors 

or additional transmission lines. Thus mitigation would not be warranted. 

5.3.1.3 Important Terrestrial Species and Habitats 

This section discusses the potential impacts of operation of the proposed Units 3 and 4 to 

important species and habitats, including Federally and State-listed species, ecologically 

important habitats (including wetlands), and commercially and recreationally important species. 

Important Terrestrial Species and Habitats – Site and Vicinity 

This section discusses important terrestrial species and habitat in the vicinity of the STP site. 
Operational Impacts at the Proposed Site 

NUREG-1937 5-28 February 2011 

Federally Listed Species 

The Federally listed species that potentially occur on the STP site and in the vicinity are 

described in Chapter 2, Table 2-9 respectively. No designated critical habitat exists in the 

vicinity of the STP site. Of the four Federally listed species that are known to occur in 

Matagorda County, only two have been found on or in the vicinity of the site: the American 

alligator (Alligator mississippiensis), and the northern Aplomado falcon (Falco femoralis 

septentrionalis). The American alligator occurs on the STP site and uses the habitats found 

there (STPNOC 2010a). The Northern Aplomado falcon has been observed within 10 mi of the 

STP site (NAS 2009), but it is not known to use the habitats on the site. Operation of proposed 

Units 3 and 4 would not be expected to cause impacts to the Federally listed species that are 

not found on the site or in the vicinity. 

The American alligator commonly occurs in the wetlands and open waters of the STP site. This 

species is listed as threatened by the FWS due to similarity of appearance to the endangered 

American crocodile (Crocodylus acutus). Alligators currently use aquatic and wetland habitats 

on the STP site and can be found adjacent to existing buildings where drainages contain water. 

Increased traffic and new roadways associated with plant operations may provide increased 

potential for alligators to encounter vehicles and be killed; however, the likelihood of significant 

mortality to the alligator population as a result of road kills is considered to be low. Because 

alligators are accustomed to the noise of vehicle traffic and the presence of workers on the STP 

site, it is unlikely that this species would suffer any significant adverse impacts onsite from 

operations of proposed Units 3 and 4. 

The northern Aplomado falcon has been observed within 10 mi of the STP site, but is not known 

to nest in the area or to use habitats on the STP site. This species has been reintroduced to the 

Texas Gulf Coast over the past 15 years on Matagorda Island, which is more than 35 mi from 

the STP site (TPWD 2003). Operation of proposed Units 3 and 4 is not expected to negatively 

affect the falcon or to permanently displace this species from critical forage, resting, or nesting 

areas. 

The American alligator is the only Federally listed species known to occur on the STP site and 

alligators have not been observed using the habitats at or immediately adjacent to the sites for 

proposed Units 3 and 4, and they are not expected to be negatively affected or permanently 

displaced from critical forage, resting, or nesting areas by operations. Thus, impacts of 

operations to Federally listed species are expected to be minimal. 

State-Listed Species 

Six bird species listed as threatened or endangered by the State of Texas have been observed 

recently on the STP site (STPNOC 2010a). The brown pelican (Pelecanus occidentalis) has 

been observed at the MCR and may use water bodies on the site for resting, foraging, and 
 Operational Impacts at the Proposed Site 

February 2011 5-29 NUREG-1937 

drinking. The bald eagle (Haliaeetus leucocephalus) is a resident on the site and nests within 

the STP site boundary. The white-faced ibis (Plegadis chihi), reddish egret (Egretta rufescens), 

peregrine falcon (Falco peregrinus), and white-tailed hawk (Buteo albicaudatus) have been 

observed during the annual Christmas Bird Count (NAS 2009). 

Brown pelicans nest within Matagorda Bay and the Gulf Intracoastal Waterway (GIWW), which 

is within 10 mi of the site. Brown pelicans are a relatively recent visitor to the STP site. Brown 

pelicans would be expected to avoid habitats immediately adjacent to the proposed Units 3 and 

4 because of increased noise levels and human and vehicle activities. Brown pelicans appear 

to be using the water features found on the STP site, including the MCR and Colorado River, 

which are generally distant (greater than 1000 ft) from the proposed units. Brown pelicans may 

avoid that region of the MCR that is closest to the proposed mechanical draft cooling towers for 

proposed Units 3 and 4 because of operational noise and increased activity. However, because 

the MCR is quite large and other aquatic habitats are readily available, no significant impact is 

likely to occur to pelican behavior or resting and feeding patterns. 

None of the other State-listed species (Chapter 2, Table 2-10) were observed using the habitats 

immediately adjacent to the proposed Units 3 and 4 during recent ecological surveys (ENSR 

2007a). The bald eagle nest is located more than a mile from the power blocks and cooling 

towers (STPNOC 2010a). The white-faced ibis and reddish egret were observed using 

wetlands on the STP site and would not be expected to use or forage in the grassland and 

disturbed habitats that are adjacent to proposed buildings and the cooling towers. White-tailed 

hawks have been observed on the STP site and potentially use a variety of the habitats found 

on the STP site for hunting and resting. However, no nest sites are known to occur in the 

vicinity of the proposed units. Peregrine falcons could fly over the STP site during spring 

migration from Mexico and might hunt in some habitats onsite. Noise levels associated with 

operations of cooling towers and human presences and activities would likely cause these birds 

to avoid the immediate vicinity of the towers and power blocks. 

These six bird species are not expected to be negatively affected or permanently displaced from 

critical forage, resting, or nesting areas by operations of the proposed Units 3 and 4. Thus, 

impacts of operations to State-listed species are expected to be minimal. 

Ecologically Important Habitats—Site and Vicinity 

No areas designated as “critical habitat” for threatened or endangered species, State or Federal 

parks, wildlife refuges, preserves, or wildlife management areas occur on or immediately 

adjacent to the STP site. A number of palustrine emergent and palustrine scrub – shrub 

wetlands are located on the STP property around the proposed facilities. All of the wetland 

areas are more than 1300 ft from the proposed mechanical draft cooling towers for proposed 

Units 3 and 4 and, thus, would not be likely to be affected by salt deposition above the 

8.9 lb/ac/mo threshold. No fogging or icing are estimated to occur, and would not be expected 
Operational Impacts at the Proposed Site 

NUREG-1937 5-30 February 2011 

to negatively affect wetland habitats on the site. Operations are not expected to adversely 

affect any of the three wildlife refuges that are near the STP site. The Clive Runnells Mad 

Island Marsh Preserve and the Texas Parks and Wildlife Department (TPWD) Mad Island 

Wildlife Management Area (WMA) are more than 3 mi south of the STP site and would not be 

affected by noise, traffic, salt drift, fogging, or icing. The Big Boggy National Wildlife Refuge is 

approximately 9 mi from the site and would not be likely to be affected by operations of the 

proposed units. In summary, operation of proposed Units 3 and 4 would be expected to have 

minimal impacts to important habitats on the STP site or in the vicinity. 

Commercially and Recreationally Important Species—Site and Vicinity 

Game species such as white-tailed deer (Odocoileus virginianus), feral pigs (Sus scrofa), 

eastern cottontail (Sylvilagus floridanus), swamp rabbit (S. aquaticus), mourning doves 

(Zenaida macroura), and many different species of waterfowl are common inhabitants of the 

STP site. Potential impacts of operating proposed Units 3 and 4 include increased noise levels 

near the cooling towers that may cause these wildlife species to avoid the immediate area and 

increased activity and traffic that also would cause wildlife to avoid the habitats immediately 

adjacent to the proposed units. Drift, fogging, and icing are expected to cause negligible or no 

impacts to habitats and would not be expected to affect important game species. Although 

animals may avoid habitats adjacent to the new units during operations, the STP property 

contains large expanses of aquatic and terrestrial habitat where these species would likely 

relocate. Thus, operational impacts to commercially and recreationally important species would 

be minimal, and no mitigation would be warranted. 

Important Terrestrial Species – Transmission Lines 

Five existing transmission lines would be required to support the proposed Units 3 and 4. 

Federally and State-listed species from both Matagorda and Wharton Counties were considered 

in the review. 

Federally Listed Species 

In the event that threatened or endangered species are found within the transmission line 

corridors, established procedures (AEP 2009) would be followed including procedures outlining 

the process of communicating with Federal agencies. No occurrences of Federally listed 

species have been reported along any of the transmission corridors (STPNOC 2010a). 

Because only existing corridors would be used for transmission of power generated by 

proposed Units 3 and 4, no additional impacts would be expected to occur to any Federally 

listed species from operation and maintenance of transmission lines and corridors associated 

with the proposed units. 
 Operational Impacts at the Proposed Site 

February 2011 5-31 NUREG-1937 

State-Listed Species 

State-listed species that occur within or adjacent to the transmission corridor that would be 

upgraded to support proposed Units 3 and 4 include the bald eagle and the State species of 

concern, coastal gay-feather (Liatris bracteata). Vegetation management activities along the 

corridors are not likely to affect these species. Because only existing corridors would be used 

for transmission of power generated by proposed Units 3 and 4, no additional impacts would be 

expected to occur to any State-listed species from operation and maintenance of transmission 

lines and corridors associated with the proposed units. 

Commercially and Recreationally Important Species 

Transmission corridors that would transmit power generated from the proposed units travel 

through a variety of habitats that support large and small game as well as waterfowl species. 

Because no new transmission corridors are planned to support proposed Units 3 and 4, no 

additional impacts would be expected to occur to any commercially or recreationally important 

species as a result of operations of the proposed units. 

Important Habitats 

No areas designated by the FWS as “critical habitat” for threatened or endangered species 

occur on or immediately adjacent to existing transmission corridors associated with existing STP 

Units 1 and 2 and proposed for use with proposed Units 3 and 4. None of the transmission lines 

cross State or Federal parks, wildlife refuges, preserves, or wildlife management areas. The 

impacts of transmission line corridor maintenance on floodplains and wetlands were evaluated 

in the GElS for license renewal (NRC 1996a). The impacts were found to be of small 

significance at operating nuclear power plants, and these included transmission line corridors of 

variable widths. Because no new transmission corridors would be required for operation of the 

proposed new units, the potential impacts of maintaining existing corridors would be minimal. 

5.3.1.4 Terrestrial Monitoring 

No monitoring of terrestrial ecological resources has been required at the STP site or along its 

associated transmission corridors since the MCR was filled, and there is no ongoing ecological 

monitoring of these resources. Because the potential impacts of operations of STP 3 and 4 on 

terrestrial resources would be minimal, STPNOC does not propose any additional monitoring 

during operations (STPNOC 2010a) 

5.3.1.5 Summary of Terrestrial Ecosystems Impacts 

The potential impacts of operating the proposed new units on vegetation, birds, and shoreline 

habitat are likely to be minimal. The potential impacts of operation and maintenance of 

transmission lines and corridors on terrestrial resources are considered minimal, assuming 

BMPs are followed. 
Operational Impacts at the Proposed Site 

NUREG-1937 5-32 February 2011 

The review team considered the potential terrestrial ecological impacts of operating new 

generation facilities at the STP site including the associated heat dissipation system, 

transmission lines, and associated maintenance. Given the information provided by the 

applicant, interactions with State and Federal agencies, the public comment process, and the 

review team’s own independent review, the review team concludes the impacts from operation 

of the new facilities and associated transmission line corridors would be SMALL, and additional 

mitigation would not be warranted. 

5.3.2 Aquatic Impacts 

This section discusses the potential impacts of the operation of the proposed Units 3 and 4 on 

the aquatic ecosystem in the onsite water bodies, the Colorado River and operation and 

maintenance of the transmission lines. The operation of proposed Units 3 and 4 would directly 

affect the aquatic resources in the Colorado River and MCR. Indirectly, the operation of 

proposed Units 3 and 4 would affect the aquatic resources in onsite drainage areas, Little 

Robbins Slough, and Matagorda Bay. 

5.3.2.1 Aquatic Resources – Site and Vicinity 

Sloughs, Drainage Areas, Wetlands, and Kelly Lake 

Impacts on aquatic resources in the onsite water bodies, (e.g., the sloughs, drainage areas, 

wetlands, and Kelly Lake) from operation activities associated with proposed Units 3 and 4 

would primarily be associated with stormwater drainage. The extensive drainage system 

already on the STP site would be modified during site preparation and development of the 

proposed units. The SWPPP that would be approved by TCEQ for implementation during site 

preparation and development would require reestablishing drainage patterns and other 

permanent measures to manage stormwater upon completion of proposed new 

units (STPNOC 2010a). 

The other potential impact on aquatic resources during operation is from the release of water 

from the MCR into drainage areas onsite, including Little Robbins Slough, and to the south of 

the site. Water from these relief wells is discharged to a surface water ditch that surrounds the 

MCR and flows away from the reservoir through the site’s natural drainage features 

(STPNOC 2010a). As discussed in Section 5.2.3, water from the MCR is lost through seepage 

to groundwater and to the 770 pressure-relief wells located in the above-grade dike surrounding 

the MCR. While the volume of seepage to the onsite areas and the offsite areas is difficult to 

estimate based on the available water monitoring measurements, water constituents that are 

from the operation of Units 1 and 2, notably tritium, in the groundwater, relief wells, and Little 

Robbins Slough confirms the connection of seepage from the MCR (STPNOC 2010a). As 

STPNOC increases the water level in the MCR from 47 to 49 ft., there would be an incremental 

increase in water seepage to the onsite waterbodies and to the wetlands south of the site. 
 Operational Impacts at the Proposed Site 

February 2011 5-33 NUREG-1937 

Sections 2.3.3.1 and 5.2.3.1 discuss the water quality of the MCR. While the MCR water 

contributes flow to these onsite water bodies, the water quality of the MCR would be monitored 

and maintained such that the MCR water would not contribute to the degradation of these onsite 

water bodies. Water quality monitoring during the 2007-2008 aquatic ecology studies in the 

MCR showed that the salinity (a surrogate for dissolved solids) was on average 1.6 parts per 

thousand (ppt) (ENSR 2008a). As discussed in Section 2.4.2, the aquatic biota in the onsite 

drainage system and Little Robbins Slough are generally tolerant of saline waters and would not 

likely be affected by seepage from the MCR. 

The review team concludes that, based on the use of stormwater systems comparable to that 

currently used for the STP site and water quality conditions in the MCR currently supporting 

diverse aquatic community, the impacts to onsite water bodies from the operation of the 

proposed Units 3 and 4 would be minimal. 

Colorado River and MCR 

Water Intake and Consumption

For aquatic resources, the primary concerns related to water intake and consumption are the 

impacts related to the relative amount of water drawn from the cooling water source (Colorado 

River and MCR) and the potential for organisms to be impinged on the intake screens or 

entrained into the cooling water system. Impingement occurs when organisms are trapped 

against the intake screens by the force of the water passing through the RMPF on the Colorado 

River and the circulating water intake structure (CWIS) on the MCR (69 FR 41576). 

Impingement can result in starvation and exhaustion, asphyxiation (water velocity forces may 

prevent proper gill movement or organisms may be removed from the water for prolonged 

periods of time), and descaling (69 FR 41576). Entrainment occurs when organisms are drawn 

through the RMPF from the Colorado River into the MCR or through the CWIS in the MCR into 

the proposed Units 3 and 4 cooling system. Organisms that become entrained are normally 

relatively small benthic, planktonic, and nektonic (organisms in the water column) forms, 

including early life stages of fish and shellfish, which often serve as prey for larger organisms 

(69 FR 41576). Due to the use of the MCR at STP, entrained organisms from the Colorado 

River have survived the stresses of the intake system and colonized the MCR, creating a rather 

diverse aquatic community that is removed from the rest of the ecosystem in the region. 

However, as entrained organisms pass through the CWIS into the plant’s cooling system, they 

are subject to mechanical, thermal, and toxic stresses, and survival is unlikely. 

A number of factors, such as the type of cooling system, the design and location of the intake 

structure, and the amount of water withdrawn from the source water body greatly influences the 

degree to which impingement and entrainment affect the aquatic biota. The 7000-ac MCR is 

considered a closed-cycle cooling system since the water in the reservoir continues to circulate 

from the MCR, into the plant, and back again. Water loss from the MCR through evaporation, 
Operational Impacts at the Proposed Site 

NUREG-1937 5-34 February 2011 

seepage, and discharge is made up from the Colorado River. Closed-cycle recirculating cooling 

water systems can, depending on the quality of the makeup water, reduce consumptive water 

use by 96 to 98 percent of the amount that the facility would use if it employed a once-through 

cooling system (69 FR 41576). The water withdrawal rate for the MCR to operate Units 1 and 2 

has probably been lower compared to other cooling water system designs after the MCR was 

filled, and the impingement, entrainment, and entrapment of aquatic organisms may also be 

lower compared to other cooling systems. Typically, organisms entrained by a power plant are 

assumed to be killed within the plant system. However, the survey of the MCR in 2007 and 

2008 indicates that many individuals of numerous species have survived entrainment at the 

RMPF and are living in the MCR. While these organisms have survived entrainment of the 

pumps at the RMPF, overall the entrainment has led to a loss of the organisms in the Colorado 

River and these organisms no longer contribute to the richness of river community. 

Location of the intake system is another design factor that can affect impingement and 

entrainment. The RMPF is located on the Colorado River, which is designated as a tidal stream 

and includes essential fish habitat (EFH) for Federally managed fish and shellfish species 

(GMFMC 2004). Locating intake systems in such areas with sensitive biological communities is 

generally considered a negative factor in protection of aquatic life (69 FR 41576). However, the 

segment of the river where the RMPF is situated (Segment C) has fewer organisms and less 

species richness than the downstream segment of the river, closer to the GIWW (Segment A) 

(ENSR 2008b). During 2007-2008, 18 percent of the total number of individuals collected were 

from Segment C as compared to 44 percent from Segment A; and 42 species were collected 

from Segment C as compared to 62 species from Segment A (Figures 2-22 and 2-23 in 

Chapter 2). 

Operation of the RMPF is based on the need for makeup water in the MCR, and Section 5.2.2.1 

discusses the conditions when STPNOC would pump water from the Colorado River into the 

MCR. One of these conditions is pumping makeup water during periods of high flows in the 

Colorado River. Pumping at high-flow conditions minimizes impacts to aquatic organisms in the 

water column because the organisms are likely to remain in the river flow and not likely to be 

caught in the influence of the water being pumped into the RMPF located on the shoreline 

(STPNOC 2008a, b, 2010a). During the 2007-2008 aquatic ecology studies in the Colorado 

River, there was an inverse relationship between high river flow conditions and low densities of 

fish (as expressed in the catch per unit effort) (ENSR 2008b; STPNOC 2008a, b). Salinity can 

be an indicator of an influx of estuarine species moving up the river from the GIWW. STPNOC 

has stated that the salinity of the water being pumped would be monitored, and when the 

pumped water exceeds 3 ppt, the traveling screens would be monitored for increased 

impingement. The operation of the fish-return system at the RMPF is a function of river flow 

and the amount of debris and organisms removed in the screen wash discharge 

(STPNOC 2008a). 
 Operational Impacts at the Proposed Site 

February 2011 5-35 NUREG-1937 

The RMPF was designed to position the traveling intake screens in parallel with the flow in the 

river (69 FR 41576), or “flush” to the river bank with no projecting structures that create eddies 

and countercurrents that would cause entrapment (NRC 1986; STPNOC 2010a). Most 

organisms likely to be entrained or entrapped would occur in higher densities in the main river 

channel and less likely to be removed from the river by an intake facility sited on the shoreline. 

Entrapment of aquatic organisms in a restricted area (e.g., in the sedimentation basin between 

the RMPF intake screens and the pumps and in the MCR) can lead to congregation of the 

organisms, and if environmental conditions change, the organisms may be harmed. Under such 

conditions, entrapment can increase impingement of aquatic organisms. 

Water velocity associated with the intake structure greatly influences the rate of impingement, 

entrainment, and entrapment of organisms at a facility. The higher the approach and/or 

through-screen velocity, the greater the number of organisms impinged, entrained, or 

entrapped. A low approach velocity reduces the probability of impingement because most fish 

can overcome such low flows to avoid the intake screens. STPNOC has determined that the 

RMPF has a maximum design approach velocity in front of the traveling screens of 

approximately 0.5 fps based on a maximum pumping rate of approximately 538,000 gpm 

(STPNOC 2008b, 2010a). As discussed in Section 5.2.2.1, the review team independently 

calculated that the approach velocity was dependent on the withdrawal rate of the RMPF; for 

withdrawals of 60 cfs (26,930 gpm) and 1200 cfs (538,600 gpm), the maximum approach 

velocities would be 0.025 and 0.5 fps, respectively. Conditions resulting in the approach 

velocity of approximately 0.5 fps have been determined to occur infrequently (see Section 

5.2.2.1). At an 0.5 fps approach velocity, impingement and entrapment losses are expected to 

be minor. 

Other design features at the RMPF would also help to reduce impingement mortality 

(69 FR 41576). In front of the traveling water screens are coarse trash racks (with 4-in. spacing 

between bars) and stop log guides that allow fish that approach the RMPF to have free 

passage, reducing entrapment and impingement. The existing traveling screens have a 3/8-in. 

mesh, and operate intermittently to coincide with the intermittent withdrawal of river water 

(STPNOC 2010a). STPNOC has not committed to a type of screen for refurbishment or 

replacement so the review team is assuming that the mesh size of any new or refurbished 

screens would have a mesh size less than or equal to 3/8-in. Fish collected on the traveling 

screens can be returned to the river via the sluice and a fish bypass pipe. The discharge point 

of the fish bypass system is at the downstream end of the intake structure, approximately 2 ft 

below normal water elevation (STPNOC 2010a). During high-flow conditions, the accumulation 

of debris on the traveling screens is too high to open the fish bypass system, and screenwash 

discharge is directed to the sluice trench catch baskets rather than back to the river. Generally, 

the fish bypass system is closed when river flows are greater than 4000 cfs, and the system is 

occasionally closed when flows are greater than 2000 cfs (which has occurred from 2001-2006 

only 7 percent of the time) (STPNOC 2008a, b, 2010a). Impingement mortality can be reduced 
Operational Impacts at the Proposed Site 

NUREG-1937 5-36 February 2011 

based on the procedures for operating the RMPF. Operators at the RMPF are required to 

monitor for increased impingement rates on the traveling screens, and factors like river flow, 

salinity, and observations of impingement are used to determine whether pumping should 

continue (STPNOC 2008a, b, 2010a). 

Entrainment and impingement studies were conducted as part of the licensing process for STP 

Units 1 and 2, and were discussed in the Final Environmental Statement (FES) for operation 

(NRC 1986). Studies conducted in 1975-1976, prior to construction of the RMPF, estimated 

entrainment of the larvae of the most common fish and crustacean species during an 8-month 

period at Station 2 on the Colorado River (Figure 2-21): 3.37 x 106

 Atlantic croaker 

(Micropogonias undulatus), 1.35 x 106

 Gulf menhaden (Brevoortia patronus), 1.32 x 106 blue 

crab (Callinectes sapidus), 5.44 x 105

 bay anchovy (Anchoa mitchilli) and 1.1 x 104 shrimp 

(undetermined species) larvae. There was a seasonal fluctuation of the species collected 

monthly during the study. Atlantic croaker larvae were entrained mainly from November through 

January. From January through April 1976, Gulf menhaden larvae were the predominant 

species. Anchovy eggs and larvae occurred sporadically throughout the sampling year. 

Highest numbers of juvenile and megalops of blue crab were collected in October, but there 

were increased numbers taken in September and April (NRC 1986). 

The entrainment studies in 1983-1984 in the Colorado River were conducted during the filling of 

the MCR (NRC 1986). Different species of fish and crustaceans were collected compared to 

the studies in 1975-1976. The primary fish species collected in the vicinity of the plant intake 

were bay anchovies, followed by darter goby (Ctenogobius boleosoma) and naked goby 

(Gobiosoma bosc). The most common crustacean collected were the zoea larval stage of the 

Harris mud crab (Rhithropanopeus harrisii), followed by the zoeal and postlarval stages of the 

ghost shrimp (Callianassa spp.). Postlarval stages of the brown shrimp (Farfantepenaeus 

aztecus) and white shrimp (Litopenaeus setiferus) and the juvenile stages of the blue crab were 

collected only sporadically in river samples. The variety of species collected illustrates that the 

lower Colorado River is utilized as a nursery area by estuarine and marine organisms (NRC 

1986). The seasonal variations in species and numbers of individuals found in these studies 

emphasize the complexity of the aquatic environment in the Colorado River and in the vicinity of 

the RMPF. These variations are a function of the species’ reproductive periods, changes in the 

flow of the river, the mixture of freshwater coming down the river, and tidal influence of the Gulf. 

The FES for operation of Units 1 and 2 (NRC 1986) concluded that entrainment losses for the 

species that were collected during the two studies would not constitute a significant impact to 

their respective populations for several reasons. They estimated that the actual entrainment 

losses would probably be near a median value of about 10 percent of the organisms passing the 

RMPF. This value represents the loss of organisms in the influence of the tidal flow in the river 

and does not represent the entire populations of those species in the Colorado River. The 

organisms that use the lower Colorado River as a nursery also use many other tidal river 
 Operational Impacts at the Proposed Site 

February 2011 5-37 NUREG-1937 

systems along the Texas Gulf coast, and the area influenced by the RMPF is not unique. The 

most common species collected in the entrainment studies were bay anchovy, Gulf menhaden, 

Atlantic croaker and blue crab; the species are ubiquitous and abundant along the Texas and 

Gulf coast. The reproductive potential (fecundity) for the species collected during the 

entrainment studies is high (e.g., one female blue crab can produce over her lifetime at least as 

many larvae as were projected to be entrained by the studies). And finally, the most makeup 

water withdrawal would occur during high river flow conditions when tidal flows are low at the 

RMPF, which is when the concentrations of estuarine and marine organisms would be lowest 

(NRC 1986). 

Impingement studies at the RMPF were conducted in 1983-1984, while river water was being 

pumped into the MCR. The study reported that the highest numbers of organisms impinged 

over a 30-minute collection period for two intake screens at the RMPF were 64 organisms in 

July and 13 organisms in September. The number of organisms that could be impinged for all 

24 screens at the RMPF and for two pumping rates (85 cfs and 260 cfs) was extrapolated to be 

from 156 to 768 individuals over a 30-min period. Gulf menhaden was the most common 

species impinged, which relates to their small size (and thus, relatively low swim speed), dense 

schooling nature and high relative abundance at the site. The report estimated that Gulf 

menhaden could constitute about 65 percent of the total number of all individuals impinged at 

the RMPF. The other major species that could be impinged include: Atlantic croaker 

(16 percent), bay anchovy (10 percent) and mullet (8 percent, undetermined species). The 

remaining species that were collected during the impingement study were expected to make up 

less than 1 percent of all the individuals impinged. This impingement study has been the only 

study conducted to date in the Colorado River to report collection of the commercially important 

pink shrimp (Farfantepenaeus duorarum), and during that study, less than 10 individuals were 

collected over six months (NRC 1986). 

The FES for operation of Units 1 and 2 (NRC 1986) concluded that impingement losses would 

have only a minor effect on the biota of the Colorado River. The reasons cited for the minor 

impacts due to impingement included those mentioned above for perspective on entrainment 

losses (e.g., the species are ubiquitous and the number of similar habitat areas along the Texas 

Gulf coast). Additional reasons cited included design elements of the RMPF that should reduce 

impingement losses. For example, the mounting of the intake screens on the RMPF flush with 

the shoreline and without protruding sidewalls into the flow of the river would reduce entrapment 

and concentration of organisms ahead of the screens. Also, the location of the screens would 

decrease eddy currents downstream and allow free passage of the organisms into the main 

channel. Trash racks and the fish handling and bypass system were other features cited that 

would reduce impingement losses. Finally, the location of the intake structure was designed to 

use the upper stratum of the river water that is primarily freshwater flowing downstream in the 

river and not the lower portion of the river in the salt wedge where the estuarine organisms are 

most common (NRC 1986). 
Operational Impacts at the Proposed Site 

NUREG-1937 5-38 February 2011 

Since the impingement and entrainment studies for the RMPF were conducted, the Corps 

completed the Mouth of the Colorado River Project, diverting the Colorado River flow from the 

Gulf into Matagorda Bay (Wilber and Bass 1998; Corps 2005). As discussed in Section 2.4.2.1, 

the diversity of aquatic species has increased since the diversion of the river. Of the most 

common species impinged during the 1983-1984 studies (NRC 1986), Gulf menhaden, striped 

mullet (Mugil cephalus) and Atlantic croaker continue to be the most common species of fish 

collected around the RMPF, and probably are the most common species impinged today for the 

same reasons speculated above. The lack of studies over time in the lower Colorado River 

makes it difficult to conclude if the aquatic communities are stable based on the changes in the 

river system and the relationship of the species distributed in the region to the flow of freshwater 

and tidal changes. However, the results and conclusions of the earlier impingement and 

entrainment studies mentioned above are still applicable because the design features of the 

RMPF that would minimize losses of organisms would not change with the addition of Units 3 

and 4. 

The survey of fish and shellfish in the Colorado River in 2007-2008 (ENSR 2008a) indicates that 

the river has a large population of fresh- and saltwater species, with high species richness and a 

strong dynamic ecosystem. Impingement, entrainment, and entrapment from current operations 

of the RMPF have removed individuals from the river environment. A survey of only one year 

provides limited information about the robustness of the populations of aquatic organisms in the 

river. However, based on the limited information from the latest survey and what is known 

about the design of the RMPF, the operation of the RMPF does not appear to have changed the 

populations of the species currently found in the river. 

Based on the use of the MCR as closed-cycle cooling, frequency of pumping water, location of 

the RMPF, pumping with low intake approach velocity, and the presence of trash racks, 

traveling screens and fish return system, the review team concludes that impacts from 

impingement, entrainment, and entrapment for proposed Units 3 and 4 would be minor. 

Cooling Water Discharge System

The potential impacts to the Colorado River from the operation of the proposed Units 3 and 4 

would include effects of heated effluents on aquatic resources, chemical impacts and physical 

impacts from discharge of the MCR. 

Thermal Impacts. The discharge from the MCR would be directly into the Colorado River. 

Sections 3.2.2.2 and 5.2.3.1 discuss the location, design, and operational parameters for the 

discharge structure. Thermal impacts to aquatic organisms include heat stress, cold shock, and 

the potential for creating preferred conditions for some invasive nuisance species. 

Heat Stress. Thermal conditions influence all aspects of aquatic ecology, which includes an 

array of processes: feeding, metabolic processes, growth, reproduction, development, 
 Operational Impacts at the Proposed Site 

February 2011 5-39 NUREG-1937 

distribution, and survival (Coutant 1976). In a general sense, biota are often able to persist 

(e.g., grow, reproduce, survive) under a range of thermal conditions. While many species 

exhibit similar tolerance for temperature regimes, growth and survival are linked to optimal 

thermal conditions that are driven by species-specific requirements (Kellog and Gift 1983). 

The thermal tolerance for aquatic organisms is defined in different ways. Some definitions 

relate to the temperature that causes fish to avoid the thermal plume, other definitions relate to 

the temperature that fish prefer for spawning, and others relate to the temperatures (upper and 

lower) that may cause mortality. The effects of thermal conditions on aquatic biota can occur at 

multiple scales. Spatially, thermal pollution may exist at the site level, or may perpetuate to 

include larger extents (i.e., reach scale, watershed). Temporally, conditions resulting in water 

temperatures that exceed ambient levels may be more pronounced during certain time periods 

(i.e., winter). Finally, the consequences of thermal pollution within aquatic ecosystems may be 

confined to individual species, and depending on ecosystem conditions, may encompass a 

population-level response (Coutant 1976).

In the operating policy for the MCR, STPNOC stated that it could discharge water from the MCR 

into the Colorado River, when they are pumping water at the RMPF (SPTNOC 2009f). 

STPNOC could discharge water from the MCR when the specific conductivity of the water in the 

MCR exceeds 3000 μS/cm. STPNOC would pump makeup water from the Colorado River 

under conditions specified by the LCRA contract. The operating policy that STPNOC would 

consider when planning to discharge from the MCR includes: when the MCR water level is 

between 40 and 49 ft above MSL, when the river water conductivity is less than 2100 μS/cm, 

and when the river flow at the discharge facility is greater than or equal to 800 cfs, as permitted 

by its TPDES permit (TCEQ 2005; STPNOC 2009e). If all these conditions are met, STPNOC 

would then only discharge when the MCR water had a conductivity greater than or equal to 

3000 μS/cm. In addition to the river flow conditions, the TPDES permit limits the amount of 

discharge from the MCR to 12.5 percent of the flow in the river, limits the daily average 

discharge temperature to less than or equal to 95°F, and requires whole effluent toxicity testing 

(biomonitoring) of the MCR water being discharged (TCEQ 2005). 

Discharge of the MCR water into the Colorado River would create a thermal plume that could 

create stressful conditions for the aquatic organisms in the vicinity of the plume. Highly mobile 

aquatic species can detect changes in the water column and avoid the area all together or 

search for a passage around the temperature change. Section 5.2.3.1 discusses the 

characteristics of the thermal plume in the river during discharge of the MCR water, including 

the likely water temperature increases with the addition of two new units, the likely duration and 

frequency of discharge, and the dimensions of the thermal plume. STPNOC has only 

discharged into the Colorado River once during operation of Units 1 and 2. The information 

describing the thermal plume during four-unit operation is based on modeling bounding 

conditions to support the water quality in the MCR. No information was provided on the most 

likely time of year for discharging water (STPNOC 2010a). STPNOC and the review team used 
Operational Impacts at the Proposed Site 

NUREG-1937 5-40 February 2011 

a conservative approach in using the CORMIX model to analyze the thermal plume that could 

be created during discharge of MCR water into the Colorado River using known conditions of 

the river environment as well as conservative water and air temperatures in the vicinity of the 

discharge. The maximum thermal plume dimensions would occur during the greatest difference 

in temperatures between the MCR water and the water in the river (20.4°F), highest MCR 

discharge rate through seven ports (44 cfs per port, for a total of 308 cfs discharge rate), and 

the minimal flow in the Colorado River where the discharge would be equal to 12.5 percent of 

the total flow in the river (2464 cfs). Even under these conditions, there is always a portion of 

the river that remains at ambient water temperature allowing for passage of aquatic organisms 

on the bottom of the river and throughout much of the water column. 

During the maximum expected thermal plume dimensions, the thermal plume that is 5°F above 

ambient conditions is attached to the bottom of the river from the last port of the discharge pipe 

to 120 ft downstream, and the plume extends approximately 25 percent across the width of the 

river. In that part of the river the benthic invertebrate species (e.g., grass [Palaemonetes pugio], 

white, and brown shrimp) would be able to pass along the bottom of the river on the far side of 

the discharge structure without passing through the elevated temperature plume. 

Approximately 120 ft downstream of the last port of the discharge pipe, positive buoyancy of the 

warmer water causes the plume to rise to the surface of the river. The surface of the river is 

predicted to have an elevated temperature across the entire width from approximately 1060 ft 

from the last port of the discharge pipe to about 4400 ft downstream from the ports. As the 

plume rises to the surface and extends from bank to bank, however, there would be a portion of 

the water column that would remain at ambient river temperatures that would allow foraging fish 

(e.g., Gulf menhaden, black drum [Pogonias cromis], spotted seatrout [Cynoscion nebulosus], 

striped mullet) to move up and downstream. 

As discussed in Section 2.4.2.1, the region of the river that would be affected by the thermal 

plume corresponds with Segment B of the 2007-2008 aquatic ecology survey (Figures 2-22 and 

2-23). More than a third of all the organisms collected in the 2007-2008 study were collected in 

this portion of the river, and represented 83 percent of the total number of species collected. 

Thus, the thermal conditions of the discharge plume would create conditions that the highly 

mobile aquatic organisms could detect and would likely avoid, remaining above or below the 

discharge plume. Less mobile organisms, such as eggs, larvae, and mollusks, would be 

adversely affected by the thermal discharge in localized areas. The review team also performed 

additional CORMIX simulations and demonstrated that the size of the thermal plume would be 

smaller than that discussed above if the discharges from the ports were reduced to half their 

capacity and river flow increased, as well as if the discharges from the ports were at full capacity 

and the river flow was increased. 

The review team evaluated the possibility that the thermal plume generated by discharging the 

MCR water into the Colorado River could coincide with poor water quality for aquatic organisms 
 Operational Impacts at the Proposed Site 

February 2011 5-41 NUREG-1937 

in the river at the discharge structure. ENSR (2008b) measured water quality (e.g., salinity and 

dissolved oxygen) at various levels in the water column while collecting fish and shellfish. As 

discussed in Section 2.4.2, there are times of the year that ENSR reported the water at the 

bottom of the river was anoxic or low in dissolved oxygen (hypoxic, or dissolved oxygen less 

than 2 mg/L) when the salinity was high. The conditions were most often observed at or below 

the mid-point of the water column. The combination of the maximal thermal plume and poor 

river water conditions (e.g., high salinity and low dissolved oxygen) could force aquatic species 

to avoid the area completely. STPNOC compared the results reported by ENSR (2008b) and 

the flow in the river at the nearest gauging station at the time of the water sampling, and 

determined that during river flows greater than 800 cfs the salinity at the bottom of the river 

ranged from 0 to 18.7 ppt (STPNOC 2008c). The review team found that there was only one 

occurrence during 2007-2008 when the dissolved oxygen was less than or equal to 2 mg/L 

during river flows greater than 800 cfs. The salinity at this sampling time was 17.5 ppt (ENSR 

2008b). STPNOC has an existing TPDES permit for the discharge of water from the MCR 

outfall 001 (TCEQ 2005). The same permit would be used during operation of the proposed 

Units 3 and 4 (STPNOC 2010a). Although there is limited information available on river flow 

and water quality, based on the planned STPNOC operating policy and the requirements for the 

TPDES permit and the LCRA contract, there would be infrequent adverse effects as a result of 

the combination of the thermal plume and poor water quality. STPNOC estimated that the need 

for discharging would likely be as frequent as once every 11 days, and could be continuous for 

as much as 75 days. 

The most common juvenile and adult species collected in Segment B were Gulf menhaden, 

grass shrimp, black drum, white shrimp, and striped mullet. The juveniles and adults of these 

species would likely pass around or below the thermal plume as they move through the affected 

area while foraging. However, the thermal plume could affect the viability of eggs and larvae 

that occur in the warmer waters. Entrainment studies conducted in 1975-1976 indicated that 

these species were present as eggs and larvae in the vicinity of the RMPF, and that the 

numbers of early life stages changed over the seasons corresponding to the reproductive cycle 

of these species (from January through April for Gulf menhaden). However, the overall impact 

to these species from the effects of the thermal plume would likely be minor because these 

organisms have a high fecundity, and the number of organisms lost would be insignificant 

compared to their population in the lower Colorado River. 

The review team concludes that the effects of the thermal plume on the aquatic community 

would often be minor. If STPNOC were to discharge MCR water creating a thermal plume in 

the river when water quality in the river was poor for aquatic organisms, there could be a 

detectable avoidance by aquatic organisms and loss of viability in the non-motile life stages of 

organisms in the affected region of the river. However, the foraging behavior and high fecundity 

of the aquatic organisms that have been reported in the area would indicate that the effects from 
Operational Impacts at the Proposed Site 

NUREG-1937 5-42 February 2011 

the thermal plume and ambient river conditions is not expected to noticeably alter or destabilize 

important attributes at the population or ecosystem levels in the lower Colorado River. 

Cold Shock. Another factor related to thermal discharges that may affect aquatic biota is cold 

shock. Cold shock occurs when aquatic organisms that have been acclimated to warm water, 

such as fish in a power plant’s discharge canal, are exposed to a sudden temperature decrease. 

This can occur when a power plant shuts down suddenly in the winter. Cold shock mortalities at 

U.S. nuclear power plants located in southern regions (where temperatures rarely decrease 

below freezing) are “relatively rare” and typically affect small numbers of fish (NRC 1996a). 

In the MCR, cold shock is not likely to occur because the temperature decrease from shutting 

down one unit is moderated by the heated discharge from the units that continue to operate. 

In the case that all units would be shut down at once, the potential for cold shock would exist 

although highly unlikely considering climate for the region (Section 2.9.1). Discharge from the 

MCR into the Colorado River would likely be as frequent as once every 11 days, and could be 

continuous for as nearly 75 days. These conditions would not be frequent enough to attract 

aquatic organisms to the thermal plume. Based on this analysis, the review team concludes the 

thermal impacts on the fish populations in the Colorado River due to cold shock would be 

negligible.

Invasive Nuisance Organisms. Thermal discharges may create an environment that is 

favorable to invasive nuisance organisms. Taxa such as corbicula, giant salvinia (Savinia 

molesta), and Hydrilla have not been found in high densities in the Colorado River in the vicinity 

of STP (STPNOC 2010a). In 2008, the review team observed corbicula shells on the shoreline 

of the river above the site but did not see any nuisance organisms at the RMPF in the screen 

racks or in the fish bypass system. The 2007-2008 survey of the MCR did not report any 

nuisance organisms in the reservoir or during impingement and entrainment studies at the CWS 

for existing Units 1 and 2 although corbicula were collected in the MCR in 1981 (ENSR 2008a; 

STPNOC 2010a). It is unlikely that the MCR discharge would become a contributor of nuisance 

organisms in the Colorado River because these species have not been reported in recent 

surveys of the MCR (ENSR 2008a). However, given the past collections of corbicula in the 

MCR and the concern for the spread of the species in water bodies in Texas (STPNOC 2010a), 

routine monitoring would identify recurrence of the nuisance species.

Chemical Impacts. Other discharge-related impacts include chemical treatment of the cooling 

water. Discharges to the Colorado River would only occur from the MCR. Inputs to the MCR 

include makeup water from the river, precipitation, radioactive and nonradioactive effluents from 

the operation of the condenser and UHS for all units, and permitted chemical discharges from 

other operations (e.g., treated sanitary sewage and other effluents discussed in Section 3.4). In 

addition, stormwater and groundwater from building activities would also be discharged to the 

MCR. As discussed in Section 5.2.2.1, the most significant chemical changes in the MCR 
 Operational Impacts at the Proposed Site 

February 2011 5-43 NUREG-1937 

would be the concentration of total dissolved solids from the operation of the condenser and 

UHS.

STPNOC has an existing TPDES permit for the discharge of water from the MCR for outfall 001 

(TCEQ 2005). The same permit would be used during operation of proposed Units 3 and 4 

(STPNOC 2010a). STPNOC does not currently evaluate the water quality of the MCR in 

relation to permit conditions for chemical standards for the protection of aquatic life because 

they are not currently discharging to the Colorado River. The permit conditions also require 

evaluating acute and chronic effects on aquatic organisms from the MCR discharge prior to 

commencing discharge into the river. 

The review team has determined that the impacts from chemical discharges to the Colorado 

River would be minimal if STPNOC performs the tests for protection of aquatic life required in its 

TPDES permit and meets all other conditions of the permit (TCEQ 2005). TCEQ could require 

additional monitoring based on these tests and with further modification of the discharge permit. 

Physical Impacts. Physical effects from the operation of the blowdown discharge facility in the 

Colorado River could affect aquatic resources, particularly through scouring of aquatic habitat. 

The structure consists of seven 36-in. pipes, spaced 250 ft apart, and the pipes are directed 

45 degrees from the downstream western shore of the Colorado River. 

In the FES for construction, discharged-induced scouring of the seven-port diffuser was 

evaluated. Discharge rates through two to seven ports at a rate of 0 to 308 cfs were 

considered. NRC concluded that scouring would be limited to a few feet downstream of each 

port and would have no adverse impacts on the aquatic biota in the vicinity (NRC 1975). Since 

the discharge pipes have not been operated except for a test in 1997 (STPNOC 2010a) and the 

Colorado River in the vicinity of the pipes has not been dredged recently, the initial discharge of 

water would disturb the sediments in the area. The water would remain turbid for a period of 

time, and the suspended sediments would be dispersed downstream temporarily. Aquatic 

organisms in the scour area would be displaced, but the overall area of the river that would be 

physically affected by the discharge flow would be relatively small. 

The review team has determined that physical impacts to the aquatic ecosystem from 

discharges to the Colorado River would be minimal. No further mitigation beyond permit 

requirements would be warranted. 

Maintenance Dredging

STPNOC has stated that periodic dredging in the future would be conducted in front of the 

RMPF and barge slip. These activities are currently covered by existing permits with the Corps 

for the operation of Units 1 and 2. Dredging would remove benthic habitat and the organisms 

that are not highly mobile (e.g., mollusks). Organisms that can readily swim would likely avoid 
Operational Impacts at the Proposed Site 

NUREG-1937 5-44 February 2011 

the area during dredging activities. After dredging activities, these areas would be recolonized 

by the aquatic community. Impacts from dredging on aquatic organisms would be minor. 

5.3.2.2 Aquatic Resources – Transmission Lines 

There are approximately 480 mi of existing, 345-kV transmission lines and associated corridors 

that would be used to transmit the power generated from proposed Units 3 and 4. The 

transmission corridors primarily pass through agricultural and rangeland regions with limited 

water features. 

Operation and maintenance of the transmission lines for proposed Units 3 and 4 at STP would 

continue to be performed by the four transmission service providers currently providing those 

services (CenterPoint Energy, AEP, Austin Energy, and CPS Energy). Potential for impacts to 

aquatic resources in the transmission corridors is limited to maintenance activities and 

management of vegetation under the lines. Maintenance activities can lead to minor erosion 

and sedimentation associated with the vehicles traveling on access roads and use of equipment 

for maintaining the transmission system. Managing the vegetation under the lines can involve 

manual and mechanical methods for removal of growth. The transmission service providers 

also use chemicals along the transmission corridors, primarily herbicides for vegetation 

management. All service providers require chemical applicators to be trained in the safe use of 

herbicides and require supervisory personnel to hold Texas Department of Agriculture 

Commercial Pesticide Applicators licenses (STPNOC 2010a). 

Minimal impacts to aquatic biota from operation and maintenance activities along the 

transmission corridors are expected. Effects from erosion and sedimentation in water bodies 

along the transmission corridors are likely to be temporary and negligible. Application of 

chemicals along the transmission corridors are expected to have minimal impacts to aquatic 

biota if application of the chemicals does not occur in or over water bodies and herbicides that 

are approved for use around aquatic biota are used. Access to lines and towers might result in 

temporary impacts to wetlands resulting from the placement of board roads for use with heavy 

equipment. 

The review team concludes that the impacts of transmission line corridor maintenance activities 

on aquatic resources would not adversely affect aquatic ecosystems and that additional 

mitigation beyond that described above would not be warranted. 

5.3.2.3 Important Aquatic Species and Habitats 

This section describes the important aquatic species and habitats for the proposed Units 3 and 

4 and associated transmission corridors (to the first substations). Commercially and 

recreationally important species are found onsite and in the vicinity of STP. In addition, there 

are important habitats in the vicinity of STP. 
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February 2011 5-45 NUREG-1937 

Commercial and Recreational Species 

Activities associated with the operation of proposed Units 3 and 4 are primarily onsite and along 

the Colorado River at the STP site. Commercially and recreationally important species were 

discussed in Section 2.4.2.3. Those species that are found onsite (e.g., black drum and red 

drum [Sciaenops ocellatus]) are in water bodies that are not open to the public (e.g., in the 

MCR), and have limited ability to contribute to the populations found offsite. Impacts to those 

species would primarily be associated with stormwater drainage. As mentioned above, 

onsite water bodies would experience minimal impacts from stormwater drainage based on 

the implementation of BMPs as part of the site’s SWPPP. 

The top five most common species (Gulf menhaden, striped mullet, blue catfish 

[Ictalurus furcatus]), Atlantic croaker, and white shrimp) collected in Segment C of the river are 

commercially and recreationally important species, and some of those individuals would likely 

be affected during pumping operations. All of these species have been collected in the MCR, 

indicating that the organisms were entrained by RMPF operations. However, all of these 

species have a high fecundity and are common to the Texas Gulf coast, and thus, the impacts 

of operating the RMPF would likely have negligible impacts on the populations of these species 

in the lower Colorado River. 

Species with Designated Essential Fish Habitat 

Section 2.4.2.3 and the EFH assessment in Appendix F describe the fish species with 

designated EFH in the vicinity of the STP site (Table 2-15): king mackerel (Scomberomorus 

cavalla), Spanish mackerel (S. maculates), gray snapper (Lutjanus griseus), red drum, brown 

shrimp, pink shrimp, white shrimp, and Gulf stone crab (Menippe adina). Of the eight species, 

only red drum, brown shrimp, white shrimp, and pink shrimp have been collected during surveys 

of the river in the areas of the RMPF and MCR discharge structure (NRC 1975, 1986; ENSR 

2008a, b). Gray snapper was collected in the Colorado River in the area closest to the 

confluence with the GIWW (ENSR 2008b). All of these eight species, except for the mackerel 

species and the stone crab, have been collected in the MCR (ENSR 2008a), indicating that the 

organisms have survived entrainment by RMPF operations. 

STP Units 3 and 4 could affect species with designated EFH through operation of the RMPF 

and the discharge structure on the Colorado River as well as through maintenance dredging in 

front of the RMPF and at the barge slip. As described in the EFH assessment in Appendix F, 

operation of the proposed Units 3 and 4 could affect EFH for juvenile king mackerel; all life 

stages of Spanish mackerel, gray snapper, red drum, and Gulf stone crab; and larvae and 

juveniles of brown, pink, and white shrimp. Operation of the RMPF and discharge structure 

could create conditions in the river that juvenile king mackerel or their prey would have to avoid. 

However, since STPNOC does not plan on operating these facilities continuously, the adverse 

effects would be relatively short in duration. In addition, maintenance dredging would be 
Operational Impacts at the Proposed Site 

NUREG-1937 5-46 February 2011 

infrequent and limited in area (no more than 3 ac), and juvenile king mackerel could avoid the 

area easily. Therefore, operation of Units 3 and 4 would have minimal adverse effect on EFH 

for juvenile king mackerel. 

Operation of Units 3 and 4 would likely affect Spanish mackerel, gray snapper, and red drum 

similarly. The eggs and larvae of Spanish mackerel, gray snapper, and red drum could be 

entrained during pumping at the RMPF, and the organisms would be lost from the river 

environment. Discharge of MCR water could create thermal and chemical characteristics of the 

river water and affect the viability of the eggs and larvae of these species. However, operations 

of the RMPF and discharge system are not continuous, and their effects would be relatively 

short in duration. Maintenance dredging at the RMPF could remove or damage some eggs and 

larvae of these species. The juvenile and adult Spanish mackerel, gray snapper, and red drum 

and their prey could avoid the affected areas of the Colorado River during operation of the 

RMPF and discharge structure as well as during maintenance dredging. Overall, operation of 

Units 3 and 4 would have minimal adverse effect on EFH for all life stages of Spanish mackerel, 

gray snapper, and red drum. 

Avoiding operation of facilities on the Colorado River associated with Units 3 and 4 could be 

difficult for larvae and juveniles of brown, pink, and white shrimp. Larvae and juveniles could be 

entrained during pumping at the RMPF. While juveniles and adults could avoid discharge of 

MCR water, thermal and chemical characteristics of the plume could affect the viability of larvae. 

Maintenance dredging would also remove larvae, juveniles, adults, and their habitat in the 

dredged areas, turbidity and sedimentation could also temporarily remove habitat. Therefore, 

construction and operation of the proposed Units 3 and 4 at the STP site could affect shrimp in 

the area and are likely to have a greater than minimal but less than substantial adverse effect 

on EFH for the brown, pink, and white shrimp larvae and juveniles. 

Juvenile and adult stone crabs would be affected similarly to those life stages of the shrimp by 

operation activities in the Colorado River. While eggs are maintained by the female beneath her 

abdomen until hatching, once the zoea larvae and other larval stages of the stone crab are 

pelagic, they could be entrained by pumping at the RMPF and could be affected by thermal and 

chemical changes in the river water through discharge of MCR water. However, stone crabs of 

any life stage have not been reported in any of the surveys of the Colorado River in the vicinity 

of the STP site (NRC 1975, 1986; ENSR 2008b). Therefore, operation of Units 3 and 4 would 

have minimal adverse effect on EFH for all life stages of stone crab. 

Federally and State-Listed Species 

All the Federally listed aquatic species in Matagorda County are those listed by National Marine 

Fisheries Service (NMFS) (Table 2-14). The most likely species to be in the area are 

loggerhead (Caretta caretta), green (Chelonia mydas), and Kemp’s ridley (Lepidochelys kempii) 

sea turtles. None of these turtle species have been observed to travel beyond Matagorda Bay 
 Operational Impacts at the Proposed Site 

February 2011 5-47 NUREG-1937 

into the Colorado River. Operations of the RMPF, discharge structure and any maintenance 

dredging around the RMPF and the barge slip are not likely to affect these species. 

There are three State-listed species in Matagorda County that are listed as threatened: blue 

sucker (Cycleptus elongates), smooth pimpleback (Quadrula houstonensis), and Texas 

fawnsfoot (Truncilla macrodon). The blue sucker would be located in the Colorado River and 

not likely be in the onsite water bodies. This species was not collected during the aquatic 

surveys of the river in the 1970s, 1980s, and 2007-2008. Blue suckers move upstream in the 

spring to areas with riffles for spawning. Since spawning habitat is not within the vicinity of the 

STP site, operations of proposed Units 3 and 4 would not likely affect eggs and larvae of the 

species. Impingement of juvenile or adult blue suckers is unlikely because they prefer to forage 

in the deeper channels of the river and would not likely be drawn to the intake screens because 

they are strong enough to swim out of the current created by the RMPF when it is operating 

(TPWD 2009). They would also be able to avoid the thermal plume from the MCR discharge. 

The two State-listed threatened freshwater mussels in Matagorda County are likely to be found 

in different water bodies at STP. The smooth pimpleback could be found in the MCR and the 

Colorado River in the vicinity of STP since the species prefers small to moderate rivers as well 

as reservoirs, tolerates the flow regimes of the MCR and river, and prefers the type of substrate 

found in the MCR and river. However, since the species does not tolerate dramatic water level 

fluctuations, it is not likely to be found in the onsite water bodies. The smooth pimpleback has 

not been reported in the surveys of aquatic organisms at the STP site (NRC 1975, 1986; ENSR 

2007b, 2008a, b). Operation of the RMPF would likely not affect the adult lifestage of the 

mussel. There is no information on the reproduction of the smooth pimpleback (e.g., glochidia 

are unreported). Mussels are tolerant of temperature changes and thus the thermal plume from 

discharging the MCR is not likely to affect the species (Howells et al. 1996; TPWD 2009). 

Texas fawnsfoot has not been reported in the surveys of aquatic organisms at STP (NRC 1975, 

1986; ENSR 2007b, 2008a, b). What little is known about the species is that it has been found 

in river systems similar to the Colorado River and in flowing rice irrigation canals, but the Texas 

fawnsfoot has not been found in impoundments. Thus, Little Robbins Slough and the Colorado 

River might be suitable habitat for the species. In addition, the ponds and drainage areas that 

are located along the transmission corridor could be appropriate habitat for the Texas fawnsfoot. 

Operation of the RMPF would likely not affect the adult lifestage of the mussel. There is no 

information on the reproduction of the Texas fawnsfoot (e.g., glochidia are unreported). 

Mussels are tolerant of temperature changes and thus the thermal plume from discharging the 

MCR is not likely to affect the species. Operation and maintenance of the transmission lines 

may include vehicular traffic that could temporarily cause erosion into the ponds and drainage 

areas. If mussels are present in these water bodies, they are not likely to be affected by 

turbidity from erosion (Howells et al. 1996; TPWD 2009). 
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NUREG-1937 5-48 February 2011 

Important Habitats 

The Mad Island WMA and Clive Runnells Family Mad Island Marsh Preserve are to the 

southwest of the STP site, and the flow from Little Robbins Slough in the vicinity of STP 

provides freshwater into these wetlands. Operations of proposed Units 3 and 4 would include 

stormwater discharge from the site into the slough during precipitation events. Impacts to the 

slough would be minimized by STPNOC’s compliance with its SWPPP. In addition, there would 

be a minimal, incremental increase in flow from MCR seepage into the groundwater and reliefwell collection system as the water level in the MCR is increased from 47 to 49 ft. The 

additional water flow to the wildlife management area and preserve would likely be minimal. 

EFH is present for the region of the Colorado River that extends along the STP site up to the 

FM 521 bridge. The Colorado River and Matagorda Bay are within Ecoregion 5 of the Gulf of 

Mexico, as designated by the Gulf of Mexico Fishery Management Council in accordance with 

the Magnuson-Stevens Fishery Conservation and Management Act. Operation of the RMPF 

and the discharge structure would adversely affect EFH. Further discussion on the impacts to 

EFH and Federally managed fish and shellfish species is included in Appendix F. 

5.3.2.4 Aquatic Monitoring 

STPNOC plans to perform operation-related monitoring for water quality in accordance with 

Federal and State permitting requirements as specified by the Corps and TCEQ. The Corps 

may require monitoring as part of the Department of the Army permit associated with periodic 

dredging in front of the RMPF forebay and dredging of the barge slip during the operation of 

proposed Units 3 and 4 at STP. The TPDES permit from TCEQ would also require monitoring 

as part of the water-quality-based effluent limitations. STPNOC would have to evaluate the 

effluent from the MCR against criteria for the protection of aquatic life once discharging of the 

MCR commences (TCEQ 2005). 

5.3.2.5 Summary of Impacts to Aquatic Resources 

With regard to aquatic ecosystems, operational impacts associated with proposed Units 3 and 4 

are centered on the intake and discharge structures, but also include stormwater management, 

seepage from the MCR, maintenance dredging of the RMPF and barge slip, as well as 

maintenance and operation of the transmission corridors. The aquatic community in the vicinity 

of the STP site consists of a diversity of biota with a range of life-history requirements. Biota 

most vulnerable to entrainment and impingement include planktonic and nektonic life forms, 

respectively. As discussed, the low approach velocity (less than or equal to approximately 

0.5 fps), the use of closed-cycle cooling, the population status, and reproductive potential of fish 

most vulnerable to impingement, entrainment, and entrapment result in minimal adverse 

impacts to the aquatic ecosystem in the Colorado River. The discharge structure would deliver 

effluent with thermal, chemical, and physical inputs to the Colorado River, which would be 
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February 2011 5-49 NUREG-1937 

regulated by TCEQ. The size and configuration of the thermal plume in combination with poor 

water quality could affect the passage of the aquatic organisms in the Colorado River under 

certain flow conditions and during certain times of the year. Affected aquatic species would 

include Federally managed species with designated EFH in the Colorado River. However, the 

review team determined that STPNOC’s discharge operating policy would rarely result in 

discharges from the MCR that would create a thermal plume during times when river water 

quality is poor. Also, because of the foraging behavior and high fecundity of the aquatic 

species, population level impacts from the effects of the discharge plume are unlikely. Based 

on the foregoing, the review team concludes that the impacts on the aquatic resources on- and 

offsite from the operation of Units 3 and 4, and from maintenance and operation of the 

transmission lines and corridors would be SMALL. 

5.4 Socioeconomic Impacts 

Operations activities can affect individual communities, the surrounding region, and minority and 

low-income populations. This evaluation assesses the impacts of operations-related activities 

and of the operations workforce on the region. Unless otherwise specified, the primary source 

of information for this section is the ER (STPNOC 2010a). 

Although the review team considered the entire region within a 50-mi radius of the STP site 

when assessing socioeconomic impacts, the primary socioeconomic impact area is Brazoria 

and Matagorda Counties in Texas. Based on commuter patterns and the distribution of 

residential communities in the area, the review team found minimal impacts on other counties 

within the 50-mi radius. The socioeconomic impact area for operations differs from the 

socioeconomic impact area for building due to the smaller size of the workforce and the nature 

of operations jobs. While the building phase required a four county economic area to assess 

impact, operations workers tend to be long term, permanent employees and therefore, tend to 

gravitate to areas with shorter commutes and more services and amenities. Approximately 

83 percent of the current operations workforce for existing Units 1 and 2 lives in Matagorda and 

Brazoria Counties, and STPNOC along with the review team expect the proposed Units 3 and 4 

operations workforce to in-migrate in a similar distribution. The small percentage of workers 

(See Table 2-16) that are likely to move into other counties would be absorbed by the 

communities they move into with minimal socioeconomic impact. 

5.4.1 Physical Impacts 

This section identifies and assesses the direct physical impacts of operations-related activities

on the community, including the disturbances from noise, odors, vehicle exhaust, dust, vibration, 

and shock from blasting. It includes consideration of impacts resulting from plant operations, 

transmission corridors and access roads, other offsite facilities, and project-related 
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NUREG-1937 5-50 February 2011 

transportation of goods and materials in sufficient detail to predict and assess potential impacts 

and to show how these impacts should be treated in the licensing process. 

Potential physical impacts include noise, odors, exhausts, thermal emissions, and visual 

intrusions. The review team believes these impacts would be mitigated through operations of 

the facility in accordance with all applicable Federal, State, and local environmental regulations 

and therefore would not significantly affect the region surrounding STP. The following sections 

assess the potential operations-related physical impacts of two new units on specific segments 

of the population, the plant, and nearby communities. 

5.4.1.1 Workers and the Local Public 

There are no residential areas located within the site boundary. The nearest resident is located 

1.5 mi west southwest of the Exclusion Area Boundary (EAB) (STPNOC 2010a). The area 

within 10 mi of the STP site is predominately rural and characterized by agricultural and forested 

land, with 5170 residents (see Section 4.4.1.1). There are three other industrial facilities within 

10 mi of the STP site. 

Once the two new reactors have begun operation, they would not produce any known air 

pollutant, except for: (1) the periodic testing and operation of STP standby diesel generators 

and auxiliary power systems, (2) commuter vehicle dust and exhaust, (3) odors from operations, 

and (4) operations-based noise. The permit to operate the diesel generators would require that 

air emissions comply with all applicable regulations and the review team expects the impact air 

quality would be minimal. Access road maintenance and speed limit enforcement would reduce 

the amount of dust generated by the commuting workforce (STPNOC 2010a). During normal 

plant operation, the new units would not use chemicals in amounts that would generate odors 

exceeding Federal and State limits. STPNOC plans to use BMPs to control the odors emitted 

by chemicals and other sources during routine outages and therefore does believes the addition 

of two new reactors to the site would have only a minor impact. Air quality impacts of plant 

operation are discussed in more detail in Section 5.7. 

The proposed units would produce noise from the operation of pumps, transformers, turbines, 

generators, and switch yard equipment. The noise levels would be controlled in accordance 

with local regulations. Most equipment would be located inside structures, reducing the outdoor 

noise level. STPNOC used noise levels from existing STP Units 1 and 2, which are less than 

background noise, in evaluating noise levels for proposed Units 3 and 4. Background noise 

(ambient sound) is between 44 to 52 dBA for STP (STPNOC 2010a). Noise levels below 60 to 

65 dBA are not considered to be significant because these levels are not sufficient to cause 

hearing loss (NRC 1996a). Therefore, the review team determined the noise related effect on 

workers, residents, and recreational users of nearby areas would be minor. 
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February 2011 5-51 NUREG-1937 

5.4.1.2 Buildings 

Operations activities would not affect offsite buildings. Onsite safety-related buildings have 

been constructed to safely withstand any possible impact, including shock and vibration, from 

operations activities associated with the proposed activity (10 CFR Part 50, Appendix A). 

Except for STP site structures, no other industrial, commercial, or residential structures would 

be affected. Consequently, the review team determined there would be no operations impacts 

to onsite and offsite buildings.

5.4.1.3 Roads 

Roads within the vicinity of STP would experience an increase in traffic at the beginning and the 

end of each operations shift and the beginning and end of each outage support shift. Commuter 

traffic would be controlled by speed limits. The access roads to the STP site would be paved. 

Maintaining good road conditions and enforcing appropriate speed limits would reduce the 

impacts generated by the workforce commuting to and from STP (STPNOC 2010a). Therefore, 

the review team determined the road-related impacts from noise and dust to workers, residents, 

and other users of the roads within the vicinity of the proposed site would be minimal. 

5.4.1.4 Aesthetics 

The nearest residence is about 1.5 mi from the EAB of the proposed new units. There are 

10 residences within a 5-mi radius and the LCRA Park is 6 mi east of the STP site. The 

containment buildings and the two mechanical draft cooling towers from proposed Units 3 and 4 

would be visible from these distances. The MCR is the only current plant structure visible from 

the Lower Colorado River. The visual impacts from the new cooling towers would be from the 

towers themselves and their plumes, which would resemble cumulus clouds. The plumes would 

be rarely visible to nearby residences and not significant in size (Section 5.7). Given that the 

site has already been affected by the presence of two reactors, the visual aesthetic aspect of 

the STP site would not be significantly changed by the proposed units. 

5.4.1.5 Summary of Physical Impacts 

Based on information provided by STPNOC, review team interviews with local public officials, 

and the review team’s own independent review, the review team concludes that the physical 

impacts of operation of the proposed new units would be SMALL and adverse. 

5.4.2 Demography 

STPNOC anticipates employing 959 operations workers at the new units. In addition, STPNOC 

plans on reducing the operations workforce for Units 1 and 2 from its current workforce of 

1365 to 1062, a decrease of 303 jobs, this would result in a net increase of 656 new operations 

jobs. Some employees would already reside within a reasonable commuting distance to the 
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NUREG-1937 5-52 February 2011 

plant, for several reasons. First, most operations employees would have resided in the area 

since about the peak of construction employment for training purposes and plant start-up. 

Second, some local people already have the skills necessary to take new operations jobs after 

the units are built. Finally, local training efforts to increase the available local workforce have 

been established (Scott and Niemeyer 2008). However, maximum demographic impacts from 

operations would be derived from the net 656 workers and not just those that in-migrate for the 

operations phase. The review team assumed all the new operations employees and their 

families would migrate into the region from other locations. The average household size in 

Texas of 2.74 was used to determine the increase in population in the 50-mi region of 

approximately 1797 people. 

The review team assumed the distribution of new operations workers and their families would 

resemble the residential distribution of employees operating existing STP Units 1 and 2. 

Therefore, 60.7 percent would likely reside in Matagorda County (1091 people) and 

22.4 percent in Brazoria County (403 people) (Table 2-16 and Table 5-4). The proposed Units 3 

and 4 related population increase represents a 3 percent increase in the 2015 estimated 

populations for Matagorda County and less a than 1 percent in Brazoria County. The review 

team assumes the remaining 17 percent of operations employees and their families would be 

scattered throughout the other counties within the 50-mi region in the same distribution as the 

current workforce and would represent a negligible fraction of each community’s population. 

Table 5-4 displays the assumed distribution of new workers in tabular form. 

Based on the information provided by STPNOC, review team interviews with local public 

officials, and the review team’s own independent review, the review team concludes that the 

demographic impacts of operation of the new unit or units at the STP site would be SMALL. 

Table 5-4. Potential Increase in Resident Population Resulting from Operating Units 3 and 4 

County

Percent of 

Current STP Site 

Workforce by 

Location 

Proposed Units 3 

and 4 -Related 

Increase in 

Population 

2015 

Projected 

Population

Percentage 

Increase in 

Resident 

Population 

Matagorda 60.7% 1091 43,195 2.5% 

Brazoria 22.4% 403 311,763 0.1% 

All Other 16.9% 303 N/A N/A 

Total 100.00% 1797 

Sources: STPNOC 2010a, Texas State Data Center 2010, and review team estimates 

5.4.3 Economic Impacts to the Community 

The impacts of station operation on the local and regional economy are dependent on the 

region’s current and projected economy and population. Although future impacts cannot be 
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February 2011 5-53 NUREG-1937 

predicted with certainty, some insight can be obtained for the projected economy and population 

by consulting with county planners and population data. The economic impacts over a 40-year 

period of station operation are qualitatively discussed. The primary economic impacts from 

employing 656 net new workers to operate all units at the STP site would be related to taxes, 

housing, and increased demand for goods and services, with the largest impact associated with 

plant property tax revenues (discussed in Section 5.4.3.2). 

5.4.3.1 Economy 

The review team estimated the potential social and economic impacts on the surrounding region 

as a result of operating the proposed two new reactors at the STP site, assuming a 40-year 

operating license. Social and economic impacts would occur from additional operation 

workforce jobs, tax revenue impacts, and increased population because of in-migrating workers 

and their families. 

The in-migration of approximately 656 workers and their families would create new indirect jobs 

in the area through a process called the spending/income “multiplier effect.” Each dollar spent 

on goods and services by one person becomes income to another, who saves some money but 

re-spends the rest. In turn, this re-spending becomes income to someone else, who in turn 

saves a portion and re-spends the rest, and so on. The percentage by which the sum of all 

spending exceeds the initial dollar spent is called the “multiplier.” The U.S. Department of 

Commerce Bureau of Economic Analysis (BEA), Economics and Statistics Division, provides 

regional multipliers for industry jobs and earnings (STPNOC 2010a). The BEA earnings 

multiplier for the two county socioeconomic impact area is 1.56. Applying the multiplier to the 

review team’s estimated average operations payroll of $47 million (salary of $72,000 per 

worker) would create a total dollar impact of about $73 million per year in the region. 

BEA also estimated a jobs multiplier of 2.47. In other words, for every operations worker, an 

additional 1.47 jobs would be created in the socioeconomic impact area near the STP site. 

Therefore, the net 656 workers would create 964 indirect jobs ($26 million annual earnings) for 

a total of 1620 jobs equating to $73 million per year in total earnings. These jobs are usually in 

the retail and service industries and not highly specialized. The review team expects these 

indirect jobs to be filled by unemployed individuals living in the socioeconomic impact area. 

The operation of two new units at the STP site would also increase the number of planned 

outages, periodically bringing an additional 1500 to 2000 outage workers into the area. Current 

units undergo a scheduled refueling outage every 18 months. Once the proposed units are 

operational at least one outage would occur every year, with some years requiring two planned 

outages at different units. Most of the outage workers would stay in local hotels, rent rooms in 

local homes, or bring travel trailers so they can stay as close as possible to the STP site. In Bay 

City, the closest town to the STP site, the hotels fill up during outages for existing STP Units 

1 and 2 (Scott and Niemeyer 2008). Outside of Matagorda County, the impacts become more 
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NUREG-1937 5-54 February 2011 

diffuse because of more available hotel rooms and temporary housing. The review team 

expects the current housing pattern for outage workers would apply to the new units as well. 

The overall impact on the economy of the region from operating two new units at the STP site 

would be positive. The most pronounced economic impacts would occur in Matagorda County, 

where impacts could be noticeable and beneficial, while minimal and beneficial economic 

impacts may occur in Brazoria County. 

5.4.3.2 Taxes 

Sales, Use, Income, and Corporate Taxes 

To the extent the operations employees move into the socioeconomic area surrounding the STP 

site the two counties would experience an increase in sales and use taxes. Matagorda County 

has limited shopping and entertainment choices. Houston serves as the regional retail center, 

and Lake Jackson in Brazoria County is considered part of the greater Houston area and has 

extensive shopping and services. Also, during outages, Matagorda County would see an 

increase in hotel occupancy tax revenues. 

STPNOC estimates that the annual expenditures for goods and services during operation of 

Units 3 and 4 would be $60 million and that approximately 20 percent ($12 million) of those 

expenditures would be spent locally. The tax revenues from these expenditures are dependent 

on several unknowns such as the percent of private ownership of the purchaser and the location 

of the purchase. Only private entities are subject to sales taxes. Therefore, because it is a 

municipal utility, CPS Energy’s purchases are not taxable. Under the proposed settlement 

discussed in Section 4.4.3.2, the private ownership share of proposed Units 3 and 4 would be 

92.375 percent. CPS Energy would own the remaining 7.625 percent interest of Units 3 and 4 

(STPNOC 2010a). Any purchases made by private owners in Bay City would be subject to a 

two percent local sales tax on top of the 6.25 percent State sales taxes (STPNOC 2010a). In 

other words, local expenditures could yield up to $222,000 in local sales taxes. 

Texas has no personal income tax. Recently, Texas has changed its laws on franchise taxes 

(gross margin tax). NRG (STPNOC’s only current taxable entity) has not had to pay franchise 

taxes on existing STP Units 1 and 2 because the State has not yet completed implementing 

regulations for the new law. The franchise tax, as discussed in Section 2.5.2.2, is calculated as 

total revenue minus allowable operating costs. Because Units 3 and 4 are unregulated 

merchant plants, their future revenues and costs are not fully predictable. Therefore, NRG has 

estimated a range for annual franchise tax payments for proposed Units 3 and 4. NRG 

estimated that if the units were 100 percent taxable, Unit 3 franchise tax payments would be 

$4.7 to $5.4 million and Unit 4 would have payments of $3.9 to $4.7 million. Texas is projected 

to receive approximately $2.9 billion in franchise taxes for 2009 (STPNOC 2010a). Even if 
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February 2011 5-55 NUREG-1937 

proposed Units 3 and 4 were subject to 100 percent taxation, it would represent less than 

1 percent of Texas’s 2009 franchise taxes revenues. 

Property Taxes 

One of the primary sources of local economic impact related to the operation of new units would 

be property taxes assessed on the facility. Currently, the STP owners’ tax payments represent 

75 percent of the total property taxes received by Matagorda County (See Table 2-25). The 

current STP owners also make payments to several special districts (See Table 2-26). Property 

taxes that would be paid by the owners for the new units during operations depend on many 

factors, most of which are unknown at this time, including future millage rates, the percent 

ownership of each co-owner, and the co-owner’s taxable status. STPNOC made simplifying 

assumptions to develop an estimate of tax payments based on current millage rates, an 

assessed value similar to existing STP Units 1 and 2, and a range of ownership percentages 

(44, 60, 80, and 100 percent private ownership). The review team has reviewed these 

estimates and finds them not unreasonable. Table 5-5 provides an estimate range of the tax 

payments for the proposed units throughout the life of the plant. 

In addition to the property taxes paid on the value of the plant itself, Matagorda and Brazoria 

counties could experience an increase in property tax revenues on new homes if the influx of 

workers results in any new residential construction and/or increases in existing home prices. 

This overall impact would likely be minor and beneficial since the operations workforce and their 

families would only make up a small percentage of the existing population in the region. 

The owners of STP Units 1 and 2 are Palacios Independent School District’s (ISD’s) largest tax 

payer, representing approximately 71 percent to 99 percent their revenues between 2000 and 

2005 (Table 2-27). An increased appraised value would increase the tax payments made to the 

ISD, however Palacios ISD is a “property rich” school district (Texas Education Code Chapter 

41) and would keep only a small part of any increase in property tax revenues. The amount that 

the district would get to keep under the State’s wealth equalization laws is dependent on factors 

such as how many new students were to enroll into the district. The remainder of the property 

tax revenues collected by Palacios ISD would go to the State. As discussed in Section 4.4.3.2, 

new legislation allows school districts to negotiate a reduction in the taxable value of Units 3 and 

4 (abatement). The plants’ owners would be allowed to defer the effective date of the 

abatement for up to 7 years after the date of the agreement. The agreement would also allow 

the district and the proposed Units 3 and 4 owners to share in the tax savings. The money the 

district may receive would not be subject to the State’s equalization laws and would not have to 

be sent back to the State. Negotiations between Palacios ISD and the STP Units 3 and 4 

owners have begun. Tax payments to the Palacios school district during operations of 

proposed Units 3 and 4 would likely be minimal and beneficial because the district would have 

to send the money back to the State, however if they enter into an agreement with the STP 

Units 3 and 4 owners, impacts could be noticeable and beneficial for the Palacios ISD. 
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NUREG-1937 5-56 February 2011 

Table 5-5. Estimated Operations Impacts to Property Taxes for Matagorda County and 

Special Districts (Total Levies and Payments in Millions of Dollars)

Tax Rates and STPNOC Payments by Entity, 2006, Based on 44% Private Ownership 

Entity 

Tax Rates per 

100 Dollars of 

Assessed 

Valuation 

Total STP 

Payments Entity’s Total Levy 

STP as Percent of 

Total Levy 

Matagorda County $0.26829 $6.10 $9.04 67.5% 

Matagorda County Hospital District 0.17214 $2.57 $5.75 44.6% 

Navigation District #1 0.03758 $0.34 $0.49 70.3% 

Drainage District #3 0.022 $0.20 $0.24 82.7% 

Palacios Seawall 0.02528 $0.23 $0.33 70.2% 

Coastal Plains Groundwater District 0.00433 $0.04 $0.15 25.6% 

Totals 0.52962 $9.48 $16.00 59.2%

Hypothetical Impact Scenarios: STP 3 and 4 Property Tax Assessment, 2015 

(Assumption: STP 3 and 4 are valued similarly to STP 1 and 2) 

Scenarios: 

44% Private 

Ownership 

60% Private 

Ownership 

80% Private 

Ownership 

100% Private 

Ownership 

Tax Entity 

Estimated 

Payment 

% 

Increase 

over 2006 

Total 

Estimated 

Payment 

% 

Increase 

over 2006 

Total 

Estimated 

Payment

% 

Increase 

over 

2006 

Total 

Estimated 

Payment

% 

Increase 

over 

2006 

Total 

Matagorda County $6.10 67.5% $8.32 92.0% $11.09 122.7% $13.86 153.4%

Matagorda County Hospital 

District 

$2.57 44.6% $3.50 60.8% $4.67 81.1% $5.83 101.4%

Navigation District #1 $0.34 70.3% $0.47 95.9% $0.62 127.8% $0.78 159.8%

Drainage District #3 $0.20 82.7% $0.27 112.8% $0.36 150.4% $0.46 188.0%

Palacios Seawall $0.23 70.2% $0.31 95.7% $0.42 127.7% $0.52 159.6%

Coastal Plains Groundwater 

District 

$0.04 25.6% $0.05 34.9% $0.07 46.6% $0.09 58.2% 

Totals $9.48 59.2% $12.93 80.8% $17.24 107.7% $21.54 134.6%

Source: STPNOC 2010a

5.4.3.3 Summary of Economic Impacts 

Based on review team interviews with local public officials, and its own independent review of 

data on the regional economy, the review team concludes that the impacts on the regional 

economy of operating proposed Units 3 and 4 at the STP site would be SMALL and beneficial 

for Brazoria County and most of the rest of the region and state while Matagorda County would 

experience a MODERATE and beneficial economic impact. The impact on Matagorda County 

tax revenues is likely to be LARGE and beneficial while impacts on Brazoria County and the rest 
 Operational Impacts at the Proposed Site 

February 2011 5-57 NUREG-1937 

of the region would be SMALL and beneficial. Depending on the terms of the tax abatement 

agreement between Palacios ISD and the Units 3 and 4 owners, the impact to Palacios ISD 

would be MODERATE and beneficial. Based on the information in the ER (STPNOC 2010a) 

and the review team’s independent review, the review team concludes that the overall economic 

impacts of the operation of STP Units 3 and 4 on Matagorda County would be LARGE and 

beneficial, impacts on Brazoria County and the rest of the region would be SMALL and 

beneficial, and Palacios ISD would experience a MODERATE and beneficial impact. 

5.4.4 Infrastructure and Community Services 

Infrastructure and community services include transportation, recreation, housing, public 

services, and education. The operation of two new units at the STP site would impact the 

transportation network as additional workforce use the local roads to commute to and from work 

and possibly additional truck deliveries are made to support operation of the new units. These 

same commuters could also potentially impact recreation in the area. As the workforce 

migrates and settles in the region, there may be impacts on housing, education, and public 

sector services. 

5.4.4.1 Transportation 

Similar to the impacts discussed in Section 4.4.4.1, the impacts of the two new units’ operations 

on transportation would be greatest on the roads of Matagorda County, particularly FM 521. 

FM 521 is a two-lane FM road that provides the only access to the STP site. Beyond FM 521 

traffic is disbursed onto State highways. 

As presented in Section 2.5.2.3, the hourly stable flow capacity of FM 521 is 2300 cars per hour 

and the current use is 170 cars per hour. STPNOC estimates that the operations workforce for 

proposed Units 3 and 4 is expected to follow a similar 35-day work rotation to that used by the 

existing Units 1 and 2 operations workers, with STP Units 1 and 2 employment reduced from 

the current level of 1365 to 1062 (net loss of 303 jobs), and proposed Units 3 and 4 operations 

employment at 959 jobs. Approximately 58 percent of total operations workers would be on the 

day shift, 23 percent on the night shift, while 19 percent would be off duty (STPNOC 2010a). 

Traffic congestion would be most noticeable during the shift changes (STPNOC 2010a) when 

approximately 1172 day shift workers arrive (or depart) and while 465 night shift workers depart 

(or arrive) over a 1.5-hour period. The total shift change vehicles of 1795 (1637 plant workers 

combined with 158 non-plant-related traffic), which is within the maximum capacity of 2300 

vehicles per hour. During outages as many as 2000 additional vehicles could be on the road 

within a 24-hour period in two 12.5-hour shifts, but outage workers start times would be 

staggered so that they would not be on the road at the same time as the operations workers. 

STPNOC would schedule outages so only one unit would be down at a time (STPNOC 2010a). 

The review team concludes that the additional operations workers would have a minor impact 
Operational Impacts at the Proposed Site 

NUREG-1937 5-58 February 2011 

on the local road network and FM 521. Any mitigation measures (i.e., widening lanes) would 

have likely been implemented during the building phase and no additional mitigation would be 

warranted. 

5.4.4.2 Recreation 

A detailed description of local tourism and recreation is provided in Section 2.5. The primary 

impacts on recreation would be similar to, but smaller than, those impacts described for the 

development of the two new units in Section 4.4.4.2. Recreationists are not expected to be on 

the road at the same time as proposed Units 3 and 4 commuters (STPNOC 2010a) or otherwise 

significantly compete for recreation resources. The impacts on recreation in the vicinity of the 

STP site due to operation of proposed Units 3 and 4 are expected to be minimal. 

5.4.4.3 Housing 

Section 2.5.2.5 states there were 685 vacant rental units and 244 vacant housing units for sale 

in Matagorda County in 2000 while Brazoria County had 3168 vacant rental units and 984 

housing units for sale. Based on the 2000 data there would be enough available housing to 

support the maximum influx of workers and their families (1797 total people) into the region, but 

there is no way to know the availability of housing when operations commence. In addition, 

although the number of housing units may be sufficient to house the expected number of 

operations workers, the available units may not be the type of housing that the workers would 

desire. Matagorda County, which would likely receive the highest percentage of in-migrating 

workers relative to the available housing stock, may experience a noticeable increase in 

housing demand. Matagorda County may also experience a shift in demand toward relatively 

higher-value houses to match the relatively high wages of operations workers. 

With all four units operational, the STP site would have annual and sometimes semiannual 

outages for 17 to 35 days (STPNOC 2010a). The maximum outage workforce would be 1500 to 

2000 workers. The temporary outage workers for the existing STP Units 1 and 2 typically stay 

in area hotels or recreational vehicles. In Bay City, however, all available hotel rooms are filled 

to capacity during the current outages and once the proposed Units 3 and 4 become 

operational, this would occur twice as often. This influx of temporary workers would not be 

expected to impact the permanent housing stock or housing market in the region. 

The review team expects the overall impact on housing demand and prices from plant 

operations over the expected 40-year operation of the plant in the region would likely be minimal 

for both Brazoria and Matagorda Counties.
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February 2011 5-59 NUREG-1937 

5.4.4.4 Public Services 

Water Supply Facilities 

The STP site does not use water from a municipal system. Instead, the STP site relies upon 

five groundwater wells. STPNOC has permits to extract an average of 2.7 MGD from these 

wells, but has typically drawn an average of 1.1 MGD. STPNOC expects those wells to provide 

the additional potable water demanded for operation of the two proposed units, as well 

(STPNOC 2010a). Section 5.2 provides more detail on plant water usage. 

The average per capita water usage in the United States is 90 gpd per person (EPA 2003). 

Therefore, the new operations workforce and their families would require an additional 

161,730 gpd of potable water. Section 2.5.2.6 describes the public water supply systems in the 

analytical area, their permitted capacities, and current demands. Municipal water suppliers in 

the region have excess capacity (see Table 2-31). Regional water planning boards are 

predicting water supply shortages for the socioeconomic impact area but have implemented 

mitigation strategies. Therefore the impact on water supply would be minor. 

Waste Water Treatment Facilities 

The STP site has two private wastewater treatment facilities for the existing Units 1 and 2. As 

part of the development project for the proposed Units 3 and 4, these existing treatment facilities 

would be replaced or expanded to support the additional units (STPNOC 2010a). Therefore, 

operations would not adversely impact the existing wastewater treatment facilities. Section 2.5 

describes the public wastewater treatment systems in the socioeconomic impact area, their 

permitted capacities, and current demands. Assuming 100 percent of the water consumed 

would be disposed of through the wastewater treatment facilities, the proposed units’ plant 

operations-related population increase of 1797 people would require 161,730 gallons of 

additional wastewater treatment capacity in the socioeconomic impact area. Wastewater 

treatment facilities in the three counties have excess capacity (see Table 2-32) to handle the 

influx of construction workers. Therefore, the review team determined the impact on 

wastewater treatment from the much smaller in-migration of operations workers and their 

families would be minor. 

Police, Fire and Medical Services 

As discussed in Section 4.4.4.4 the citizen to police officer ratios for Matagorda and Brazoria 

Counties were 420:1 and 643:1, respectively. Assuming these same staffing levels, the 

assumed population increases in Matagorda and Brazoria Counties would raise the ratios to 

432:1 in Matagorda County and 643:1 in Brazoria County, representing an approximately three 

percent increase in Matagorda County citizen-to-police officer ratio and less than a one percent 

increase in Brazoria County. The in-migration of operations workers would raise the citizen to 
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NUREG-1937 5-60 February 2011 

firefighter ratios in Matagorda and Brazoria Counties from 228:1 to 235:1 and 539:1 to 540:1, 

respectively, representing an approximately three percent increase in Matagorda County and 

less than one percent increase in Brazoria County. Therefore, the in-migration of operations 

workers would have a minimal impact on police and fire services. 

Section 4.4.4.4 describes the level of medical and human services within the socioeconomic 

impact area, which the review team determined is sufficient to absorb the much larger projectrelated influx of construction workers. The expected four percent increase in population for 

Matagorda County and the less than one percent expected increase in Brazoria County would 

not impact medical facilities in those counties. 

Social Services 

New jobs created to operate and maintain the proposed new reactors would benefit the 

disadvantaged population served by the State health and human resources offices by adding 

some additional jobs to the region, which may go to people who are currently under-employed 

or unemployed, potentially removing them from some social services client lists. While the 

influx of new workers and their families may also create additional pressure on those social 

services, the review team believes the net effect of the new permanent operations workforce on 

local and State welfare and social services would minimal and beneficial. 

5.4.4.5 Education 

Section 5.4.2 discusses the review team’s underlying assumptions about the distribution of 

workers’ families within the 50-mi radius area around the proposed site. These assumptions 

indicate the expected increase in population related to operations would be 1797 people, and 

the number of in-migrating households would be 656, with an average 0.8 school-aged children 

per household. The future overall increase of 525 school-aged children would correspond to a 

318 child increase in the student population in Matagorda County (about 4.0 percent from 

current levels) and an increase of 118 children from current levels in Brazoria County (about 

0.2 percent from current levels). These increases would be spread over K-12 grades, and 

across several communities within each county. Therefore, the operations-related increase in 

class size would likely not have a noticeable effect on either county and the review team 

determined the increase in students would have a minor impact in Brazoria and Matagorda 

Counties. 

5.4.4.6 Summary of Infrastructure and Community Services 

Based on information supplied by applicant, review team interviews conducted with and 

information solicited from public officials in Matagorda and Brazoria Counties, and review team 

review of data concerning the current availability of services and current State and community 
 Operational Impacts at the Proposed Site 

February 2011 5-61 NUREG-1937 

planning efforts, the review team concludes that the operation impacts on the regional 

infrastructure and community services would be SMALL and adverse. 

5.4.5 Summary of Socioeconomic Impacts 

Based on information supplied by STPNOC, review team interviews conducted with public 

officials in the socioeconomic impact area concerning the current availability of services, and 

additional taxes that would likely fund the need for additional services, the review team 

concludes physical impacts and impacts on demographics, impacts on infrastructure and 

community services (transportation, recreation, housing, public services, and education) for 

Matagorda and Brazoria Counties would be SMALL and adverse. However, in Matagorda 

County the impacts on the economy would be beneficial and MODERATE, while tax impacts for 

Matagorda County would be beneficial and LARGE and impacts to the Palacios school district 

would be SMALL to MODERATE and beneficial. The impacts on the economy and taxes in 

Brazoria County would be SMALL and beneficial. All impacts would be SMALL in the remainder 

of the 50-mi region. 

5.5 Environmental Justice 

Environmental justice refers to a Federal policy under which each Federal agency identifies and 

addresses disproportionately high and adverse human health or environmental effects of its 

programs, policies, and activities on minority or low-income populations. On August 24, 2004, 

the Commission issued its policy statement on the treatment of environmental justice matters in 

licensing actions (69 FR 52040). Section 2.6 discusses the locations of minority and lowincome populations around the STP site and within the 50-mi radius. 

The review team evaluated whether the health or welfare of minority and low-income 

populations at those census blocks identified in Section 2.6 could be disproportionately affected 

by the potential impacts of operating two new reactors at the proposed site. To perform this 

assessment, the review team used the same process employed in Section 4.5. 

5.5.1 Health Impacts 

The review team determined through literature searches and consultations with NRC staff 

health physics experts that the expected operations-related level of environmental emissions 

would be well below the protection levels established by NRC and EPA regulations, and 

therefore would not impose a disproportionately high and adverse radiological health effect on 

minority or low-income populations. 

The results of the normal operation dose assessments (see Section 5.9) indicate that the 

maximum individual dose for the pathways identified in Section 5.9 was found to be 

insignificant, that is, well below the NRC and EPA’s regulatory guidelines. Because there would 
Operational Impacts at the Proposed Site 

NUREG-1937 5-62 February 2011 

be no significant adverse health impacts on the most exposed members of the public, there 

would be no disproportionate and adverse health impacts on any minority and low-income 

populations. Therefore the environmental justice impacts from operations would be minimal. 

The operational staff and the public would receive radiation doses from operation of the 

proposed Unites 3 and 4. Section 5.9 assesses these doses and concludes that the doses 

would be within NRC and EPA dose standards. Section 5.9 further concludes that radiological 

health impacts to the operational staff and the public for the proposed Units 3 and 4 would be 

SMALL. 

As discussed in Section 5.8.5, nonradiological health impacts from emissions during the 

operation period to the public and onsite workers would be minimal. The review team has not 

found any environmental pathway that would lead to offsite nonradiological health effects that 

would disproportionately impact to any minority or low-income populations. For example, any 

increase in traffic accidents due to heavier traffic is unlikely to have a disproportionate impact on 

any particular population subgroup. Section 5.2.3 states the effects of Unit 3 and 4 discharges 

to the lower Colorado would have a minimal effect on water quality in the Lower Colorado River 

and on groundwater in the vicinity of the STP site. In addition, Section 5.8 found that health 

impacts to the public and workers from etiological agents, noise generated by plant operations, 

and acute impacts of EMF from power lines would be minimal. The review team reviewed 

available scientific literature on chronic effects of EMF on human health and found that the 

scientific evidence regarding the chronic effects of ELF-EMF on human health does not 

conclusively link ELF-EMF to adverse health impacts. Furthermore, as discussed in 

Section 2.6.3, the review team did not identify any evidence of unique characteristics or 

practices in the minority and low-income populations that may result in different health pathway 

impacts compared to the general population (STPNOC 2010a; Scott and Niemeyer 2008). 

Therefore, the potential impacts of nonradiological effects resulting from the operation of the 

proposed two additional units would be minimal and there would be no disproportionate and 

adverse impacts felt by minority or low-income populations within the analytical area. 

5.5.2 Physical and Environmental Impacts 

The review team determined that the physical impacts from operations at the proposed STP 

Units 3 and 4 would attenuate rapidly with distance. In addition, the review team did not find 

any evidence of unique characteristics or practices among any minority or low-income 

populations of interest and expect there would be no disproportionately high and adverse 

physical or environmental impact that would be felt by any minority or low-income population. 

The following four subsections discuss each of the primary physical-environmental pathways in 

greater detail. 
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February 2011 5-63 NUREG-1937 

5.5.2.1 Soil 

Land-use impacts to transmission line corridors from operation of the proposed new units would 

be identical to existing units (see Section 4.12). Therefore, there would be no additional effect 

on any population from new transmission lines (Section 5.1). There would be very limited offsite 

deposition of salt from reactor operations and no impact to offsite populations (Section 5.7). 

Therefore, there would be no disproportionate adverse exposure to minority or low-income 

populations from this pathway. No other environmental pathways from soil were identified by 

the review team. Additionally, as discussed in Section 2.6.3, the review team did not find any 

evidence of unique characteristics or practices in the minority or low-income populations that 

may result in different soil-related impacts as compared to the general population 

(STPNOC 2010a; Scott and Niemeyer 2008). Consequently, the review team determined the 

marginal impact to soils from the proposed new units would be minimal. 

5.5.2.2 Water 

As discussed in Section 5.2, the review team determined the proposed units at the STP site 

would generate a small and infrequent thermal plume in the Lower Colorado River. In 

Section 5.3 the review team determined that this plume would not significantly affect the aquatic 

resources of the river. Therefore, there would be no disproportionate adverse impact on 

minority and low-income populations engaged in subsistence activities from this source. In 

addition, in Section 5.2 the review team found that water withdrawals from groundwater by the 

plant would not significantly affect offsite wells. Water quality effects from seepage, spills, 

withdrawal, saltwater intrusion, and nonradiological emissions also would be minimal (Sections 

5.2.3 and 5.10.2). Consequently the review team determined that the marginal impacts to the 

water from the proposed new units would be minimal. As discussed in Section 2.6.3, the review 

team did not identify any evidence of unique characteristics or practices in the minority or lowincome populations that may result in different water-related impacts as compared to the 

general population (STPNOC 2010a, Scott and Niemeyer 2008). Therefore, there would be no 

disproportionate adverse impact on minority and low-income populations who might be reliant 

on well water near the site. 

5.5.2.3 Air 

The primary air emissions from a nuclear power plant such as STP are water vapor and salt, 

which do not pose any health dangers to members of the offsite population. Because there is 

no danger to the members of the offsite public, the review team determined that there could not 

be a disproportionately large and adverse impact on minority or low-income populations. The 

total liquid and gaseous effluent doses from all four units (the existing units plus the new units) 

would be well within the regulatory limits of the NRC and EPA, implying that impacts on any 

population are likely to be minimal from this source. As described in Sections 5.7.1 and 5.10.3, 

the review team concludes that the potential impacts from all potential air sources would be 
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NUREG-1937 5-64 February 2011 

minimal. As discussed in Section 2.6.3, the review team did not find any evidence of unique 

characteristics or practices in the minority or low-income populations that may result in different 

air-related impacts as compared to the general population (STPNOC 2010a; Scott and 

Niemeyer 2008). Therefore, there would be no disproportionate adverse impact on any offsite 

minority and low-income populations from the air pathway. 

5.5.2.4 Summary of Physical and Environmental Impacts 

Based on the review team’s analysis presented in the preceding sections, the review team 

expects no disproportionate and adverse physical impacts on minority and low-income 

populations from operations. Therefore, the review team concludes the physical impacts of 

operations on minority and low-income populations would be minimal. 

5.5.3 Socioeconomic Impacts 

The review team determined that once the proposed new units are operational at the STP site, 

any building-related adverse socioeconomic impacts felt by any group within the 50-mi region 

would either stop or significantly diminish. While the addition of a net 656 new operations 

employees (most of whom would actually arrive during the construction period) would place 

pressure on local infrastructures (roads, housing, schools, hospitals, etc.), as discussed in 

Section 2.6.3, the review team did not identify any evidence of unique characteristics or 

practices in the minority or low-income populations that may result in greater impacts than those 

experienced by the general population (STPNOC 2010a; Scott and Niemeyer 2008). The 

review team believes any adverse impact would not be disproportionately felt by any 

demographic sub-group. The review team’s interviews of surrounding communities revealed a 

high level of preparedness with regard to any potential influx of temporary construction or 

permanent operations workers. Consequently the review team determined that the marginal 

socioeconomic impacts from operating the proposed new units would be minimal. 

5.5.4 Subsistence and Special Conditions 

Both STPNOC and the review team interviewed public officials and community leaders of the 

minority populations with the socioeconomic impact area in relation to subsistence practices. 

No subsistence practices were found. The review team determined there were no operationsrelated disproportionate and adverse impacts on minority or low-income populations related to 

subsistence. 

The Hispanic and Vietnamese communities in the Palacios area are engaged in fishing, but as 

commercial fishermen, not as subsistence fishermen (STPNOC 2008c, 2010a; Scott and 

Niemeyer 2008). Any subsistence fishing activity by the riverfront community, identified in 

Section 2.6, would not have either a radiological or nonradiological adverse health effect 

(Sections 5.9.2.1, 5.9.3.1, and 5.8.1). The review team also has determined that the impacts 
 Operational Impacts at the Proposed Site 

February 2011 5-65 NUREG-1937 

from chemical discharges to the Lower Colorado River would be minimal, and no additional 

monitoring would be required (Section 5.3.2.1). Impacts on aquatic species would also be 

minimal, as suggested in Sections 5.9.5.1 through 5.9.5.3. Therefore, low-income or minority 

individuals who may be engaged in subsistence fishing would not experience disproportionate 

adverse impacts. 

5.5.5 Summary of Environmental Justice Impacts 

Based on the underlying assumptions of the analysis discussed in Section 2.6, the impacts of 

plant operations on minority and low-income populations would be SMALL because no 

environmental pathways or conditions were found that would result in a disproportionate and 

adverse impact on minority or low-income populations. 

5.6 Historic and Cultural Resource Impacts 

The National Environmental Policy Act of 1969, as amended (NEPA) requires that Federal 

agencies take into account the potential effects of their undertakings on the cultural 

environment, which includes archaeological sites, historic buildings, and traditional places 

important to local populations. The National Historic Preservation Act of 1966, as amended 

(NHPA), also requires Federal agencies to consider impacts to those resources if they are 

eligible for listing on the National Register of Historic Places (such resources are referred to as 

“Historic Properties” in NHPA). As outlined in 36 CFR 800.8(c), “Coordination with the National 

Environmental Policy Act of 1969,” the NRC is coordinating compliance with Section 106 of the 

NHPA in fulfilling its responsibilities under NEPA. 

Operating new nuclear power plants can affect either known or undiscovered historic properties 

that may be located at the site. In accordance with the provisions of NHPA and NEPA, the NRC 

and the Corps are required to make a reasonable and good faith effort to identify historic 

properties in the areas of potential effect and, if such properties are present, determine whether 

or not significant impacts are likely to occur. Identification of historic properties is to occur in 

consultation with the State Historic Preservation Officer (SHPO), Native American Tribes, 

interested parties, and the public. If significant impacts are possible, then efforts should be 

made to mitigate them. As part of the NEPA/NHPA integration, even if no historic properties 

(i.e., places eligible for listing on the National Register of Historic Places) are present or 

affected, then the NRC and the Corps are still required to notify the SHPO before proceeding. If 

historic properties are present, then the NRC and the Corps are required to assess and resolve 

adverse effects of the undertaking. 

For a description of the historic and cultural information on the STP site, see Section 2.7. The 

applicant concluded that any sites that may have existed onsite would no longer retain their 

integrity because the area was heavily disturbed (STPNOC 2010a). During the site visit in 
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NUREG-1937 5-66 February 2011 

February 2008, the review team reviewed the documentation used by the applicant to prepare 

the cultural resource section of the ER. The review team did not identify any cultural resources 

that would be affected because resources that may have existed prior to the construction of 

STP Units 1 and 2 would have been destroyed during land clearing and construction activities. 

Further, no historic buildings were identified that could be affected by the visual impacts of the 

proposed units. 

For the purposes of NHPA 106 consultation, the review team does not expect any significant 

impacts on cultural and historic resources during the operation of proposed Units 3 and 4. 

Therefore, the review team concludes a finding of no historic properties affected 

(36 CFR Section 800.4(d)(1)). The Texas SHPO has concurred with this finding of no historic 

properties affected (THC 2010) and the Alabama-Coushatta Tribe of Texas has confirmed that 

the proposed action will cause no known impacts to religious, cultural, or historical resources of 

importance to the Tribe. However, the Tribe has requested further consultation if an alternative 

site is selected or in the event of any inadvertent cultural resource discoveries (Celestine 2010). 

For the purposes of the review team’s NEPA analysis, the review team does not expect any 

significant impacts on historic and cultural resources during operation of proposed Units 3 and 

4. Therefore, the review team concludes that the impacts from operations would be SMALL. 

Mitigative actions may be warranted only in the event of an unanticipated discovery during any 

ground-disturbing activities associated with maintenance of the operating facility; these actions 

would be determined by STPNOC in consultation with the Texas SHPO and other parties as 

appropriate. STPNOC has agreed to follow procedures if historic or cultural resources are 

discovered. These procedures are detailed in STPNOC’s Addendum #5 to procedure 

No. OPGP03-ZO-0025 Rev. 12 (Unanticipated Discovery of Cultural Resources) 

(STPNOC 2008d); the procedure includes notification of the SHPO at the Texas Historical 

Commission and affected Tribe(s) or other parties depending on the nature of the find. 

5.7 Meteorological and Air Quality Impacts 

The primary impacts of operation of proposed Units 3 and 4 at the STP site on local 

meteorological conditions and air quality would be associated with emissions from the routine 

operation of auxiliary equipment and cooling systems and from emissions from worker’s 

vehicles. The potential impacts on air quality are addressed in Section 5.7.1, and the potential 

impacts of operation of the cooling system are addressed in Section 5.7.2. 

5.7.1 Air Quality Impacts 

Proposed Units 3 and 4 at the STP site would each have three standby diesel generators and a 

single combustion turbine generator. These generators, each of which would be operated about 

4 hours per month, and the UHS cooling towers would be the largest stationary sources of 

emission that could affect air quality. Table 5-6 lists the expected annual emissions from these 
 Operational Impacts at the Proposed Site 

February 2011 5-67 NUREG-1937 

sources. There would be other minor emission sources onsite such as diesel-driven fire water 

pumps, but their impact on air quality would be negligible because of infrequent use. There 

would also be auxiliary boilers onsite. These boilers would not impact air quality because they 

would be electric. STPNOC has stated that “[a]ir emissions sources would be managed in 

accordance with Federal, Texas, and local air quality control laws and regulations.” 

(STPNOC 2010a). 

Table 5-6. Anticipated Atmospheric Emissions Associated With Operation of Proposed Units 

3 and 4

Diesel Generators 

(lb/yr)(a)

Combustion Turbine 

(lb/yr)(a)

UHS Cooling Towers 

(lb/yr)(b)(c)

Particulates 2500 44 45,000 

Sulfur Oxides 9200 3800 --- 

Carbon Monoxide 9200 1800 --- 

Hydrocarbons 6100 120 --- 

Nitrogen Oxides 57,900 4000 --- 

(a) STPNOC 2010a 

(b) Review team estimate based information in STPNOC 2010a on cooling tower flow and drift rate 

assuming that drift is salt particles. 

(c) Approximately 90 percent would be deposited within 1⁄2 mi of the cooling towers. 

In its ER, STPNOC briefly addresses fugitive dust during plant operations. STPNOC states that 

fugitive dust generated by the commuting work force would be minimized by properly 

maintaining hard-surfaced access roads and setting appropriate speed limits (STPNOC 2010a). 

As noted in Section 2.9, the STP site is in Matagorda County which is in attainment for all 

criteria pollutants defined in the National Ambient Air Quality Standards. Further, the closest 

Class I Federal Area is more than 100 mi from the STP site. 

Impacts of existing transmission lines on air quality are addressed in NUREG-1437 (NRC 

1996a). Small amounts of ozone and smaller amounts of NOx are produced by transmission 

lines. The production of these gases was found to be insignificant for 745-kV transmission lines 

(the largest lines in operation) and for a prototype 1200-kV transmission line. In addition, it was 

determined that potential mitigation measures, such as burying transmission lines, would be 

very costly and would not be warranted. The components needed to complete an interface 

between proposed Units 3 and 4 and STP Units 1 and 2 and ties to the regional power grid 

would be well within the range of transmission lines provided in NUREG-1437, and the review 

team therefore concludes that air quality impacts from transmission lines would not be 

noticeable. 
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NUREG-1937 5-68 February 2011 

Finally, the operation of a nuclear power plant involves the emission of some greenhouse 

gases, primarily carbon dioxide (CO2). The review team has estimated that the total carbon 

footprint for actual plant operations of Units 3 and 4 for 40 years is on the order of 

650,000 metric tons (the sum of about 190,000 metric tons for each unit from plant operations 

and about 130,000 metric tons for each unit from operations workforce transportation) of CO2

equivalent (an emissions rate of about 16,000 metric tons annually, averaged over the period of 

operation), as compared to a total United States annual CO2 emissions rate of 6,000,000,000 

metric tons (EPA 2009). Periodic testing of diesel generators accounts for about 60 percent of 

the total. Workforce transportation accounts for the most of the rest. These estimates are 

based on carbon footprint estimates in Appendix I and emissions data contained in the ER 

(STPNOC 2010a). Equipment maintenance and measures taken to mitigate transportation 

impacts, such as properly maintained asphalt or concrete roads and appropriate speed limits 

(STPNOC 2010a), would also reduce CO2 emissions, while reducing other emissions. Based 

on its assessment of the relatively small plant operations carbon footprint as compared to the 

United States annual CO2 emissions, the review team concludes that the atmospheric impacts 

of greenhouse gases from plant operations would not be noticeable and additional mitigation 

would not be warranted. 

The review team has considered the timing and magnitude of atmospheric releases related to 

operation of proposed Units 3 and 4, the existing air quality at the STP site and the distance to 

the closest Class I Federal Area, and the STPNOC commitment to manage and mitigate 

emissions in accordance with applicable regulations. On these bases, the review team 

concludes that the air quality impacts of operation of proposed Units 3 and 4 would not be 

noticeable. Based on its assessment of the carbon footprint of plant operations, the review 

team concludes that the atmospheric impacts of greenhouse gases from plant operations would 

not be noticeable. 

5.7.2 Cooling System Impacts 

The operation of the cooling system is described in Section 3.4 of the ER (STPNOC 2010a). 

Proposed Units 3 and 4 would share use of the MCR with STP Units 1 and 2. In addition, 

proposed Units 3 and 4 at the STP site would each have a six-cell mechanical draft cooling 

tower that would serve as the UHS and as a helper cooling tower for cooling during normal 

operations. Half of the cells in each tower would be used during normal operations; all cells 

would be used when heat loads are increased such as during cool down and shutdown. 

Potential atmospheric impacts from cooling system operation include fogging and subsequent 

icing downwind of the MCR, and potential impacts from the plume and drift from the cooling 

towers. In response to review team RAIs, STPNOC updated the information in the ER based on 

additional analyses using onsite meteorological data supplemented with data from the Palacios 

Municipal Airport (STPNOC 2009f). The results of the study indicate that MCR operation with 

existing Units 1 and 2 would not significantly increase fog in the vicinity. In the additional 
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February 2011 5-69 NUREG-1937 

analyses requested by the review team, STPNOC provided information on the expected 

changes in MCR temperatures and an analysis evaluating the potential impacts of the addition 

of proposed Units 3 and 4 on fog. 

Table 5-7 summarizes the results of the STPNOC analyses for two locations along FM 521. 

Fog hours are hours when fog of any density would be visible, while hours with visibility less 

than 0.3 mi are those hours when the fog would be considered to significantly restrict visibility. 

The fog hours for the Palacios Municipal Airport are included to provide context relative to 

naturally occurring fog. 

Table 5-7. MCR Fog Impact Analysis

Location 

Units 1 and 2 Units 1, 2, 3, and 4 

Fog (hr) 

Visibility 

< 0.3 mi (hr) Fog (hr) 

Visibility 

< 0.3 mi (hr) 

0.31 mi N 130 20 230 36 

1.1 mi N 33 5 77 12 

Palacios 276 43 276 43 

Source: STPNOC 2010a 

On the basis of this analysis, comparison of the fogging predictions for existing Units 1 and 2 

with the results of the previous study, STPNOC concludes that the impacts of the MCR on 

fogging would be minimal and not warrant mitigation. It further concludes that because the 

temperatures in the area are generally above freezing the impacts on icing would also be 

minimal and not warrant mitigation. 

The review team has reviewed the fogging study related to operation of existing STP Units 1 

and 2 and the information and analysis provided by STPNOC in response to the review team’s 

RAIs, and the team finds the information and analysis acceptable. Based on the results of the 

fogging study for existing Units 1 and 2, the analysis conducted by STPNOC for the addition of 

proposed Units 3 and 4, and comparison of the analysis predictions with data from the Palacios 

Municipal Airport, the review team concludes that the impacts of the MCR on fogging with the 

addition of proposed Units 3 and 4 would not be noticeable. 

STPNOC (STPNOC 2009f) conducted an evaluation of the potential impacts of the UHS cooling 

towers using the SACTI computer code (Policastro et al. 1984). The SACTI computer code 

estimates the plume characteristics and salt deposition from the operation of cooling towers. 

The results of the STPNOC analysis suggest that the average length of the plume from the 

cooling towers would range from about 0.2 mi in the summer to 0.4 mi in the winter. However, 

because these numbers are strongly affected by a relatively few occurrences of long plumes, 

they do not adequately represent the visible impact of the plume. The median length of plumes 

from the cooling towers is about 0.1 mi in each season. When plumes are calculated to extend 

beyond the site boundary they most frequently extend to the north northwest or north. Annually, 
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NUREG-1937 5-70 February 2011 

the maximum number of hours that plumes extend beyond the site boundary in a specific 

direction is 43 hours to the north northwest. During the spring and summer, plumes extend 

beyond the site boundary fewer than 10 hours in any single direction. In the STPNOC analysis, 

the visible plume did not intersect the ground, therefore STPNOC concluded that there would be 

neither fogging nor icing. 

The STPNOC analysis indicated that the annual salt deposition rate from cooling tower drift 

could be as high as 98 lb/ac/mo near the towers, decreasing to less than 8.9 lb/ac/mo at about 

0.3 mi, and less than 1 lb/ac/mo beyond about 0.8 mi. The maximum deposition rates occur 

during the summer. Most of the area with a deposition rate exceeding 8.9 lb/ac/mo is within the 

existing protected area to the north of the cooling towers, and most of the remaining area with a 

deposition rate exceeding 8.9 lb/ac/mo is between the protected area and the MCR. Based on 

experience with cooling towers reported in the license renewal GEIS (NRC 1996a), STPNOC 

concluded that the impacts of salt deposition from cooling towers would be minimal and would 

not require mitigation. 

On the basis of the analysis presented by STPNOC in the ER and the review team’s 

independent evaluation of that analysis, the review team concludes that atmospheric impacts of 

UHS cooling tower operation would be minimal. 

5.7.3 Summary 

The review team evaluated potential impacts on air quality associated with criteria pollutants 

and greenhouse gas emissions from operating proposed Units 3 and 4. The review team also 

evaluated potential impacts of cooling system emissions and transmission lines. In each case, 

the review team determined that the impacts would be minimal. On this basis, the review team 

concludes that the impacts of operation of proposed Units 3 and 4 on air quality from emissions 

of criteria pollutants, CO2 emissions, and cooling system emissions would be SMALL and that 

no further mitigation is warranted. 

5.8 Nonradiological Health Impacts 

This section addresses the nonradiological human health impacts to the public and workers 

from operating the proposed new nuclear Units 3 and 4 at the STP site. Nonradiological public 

health impacts are considered from operation of the cooling system, from noise generated by 

operations, from EMF, and from transporting materials and personnel to the site. 

Nonradiological health impacts from the same sources are also evaluated for workers during the 

operation of proposed Units 3 and 4. Section 2.10 provides background information on the 

affected environment and nonradiological health at and within the vicinity of the STP site. 

Health impacts from radiological sources during operations are discussed in Section 5.9. 
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February 2011 5-71 NUREG-1937 

5.8.1 Etiological Agents

Operation of proposed Units 3 and 4 would result in a thermal discharge to the MCR, and 

periodically water from the MCR would be discharged to the Colorado River. Thermal 

discharges have the potential to increase the growth of thermophilic microorganisms (including 

those that can cause diseases, i.e., etiological agents), in the MCR and the Colorado River. 

The types of organisms of concern include enteric pathogens (such as Salmonella spp. and 

Pseudomonas aeruginosa), thermophilic fungi, bacteria (such as Legionella spp.), and freeliving amoeba (such as Naegleria fowleri and Acanthamoeba spp.). These microorganisms 

could result in potentially serious human health concerns, particularly at high exposure levels. 

Section 2.10.1.3 discusses the incidence of water-borne diseases in Texas. Incidence of 

diseases such as Legionellosis, Salmonellosis, or Shigellosis, is possible through exposure to 

water vapor resulting from operation of proposed Units 3 and 4. However, public access to the 

STP site is limited, and there are no residences in the vicinity of the site where water vapor from 

operation of the proposed Units 3 and 4 would be likely to accumulate. 

N. fowleria is an etiological agent of concern because the amoeba lives in warm freshwaters 

and can cause a fatal disease called primary amebic meningoencephalitis (PAM). People 

contract PAM by swimming in freshwater containing the organisms. It is believed that the 

organism enters the central nervous system by water forcibly pushed up their nasal passages. 

While the conditions for exposure to N. fowleri in Texas are favorable, the incidence of 

contracting PAM is low considering the number of people in the State that recreate in freshwater 

(Yoder et al. 2009; CDC 2009; TDSHS 2010). The Centers for Disease Control and Prevention 

(CDC) and the Texas Department of State Health Services (TDSHS) have stated that it is not 

practical to monitor all swimming areas for the presence of the amoeba, and that postings of 

warning signs is unlikely to be effective in preventing infections (CDC 2008a; TDSHS 1995, 

1997). However, CDC, TDSHS, and the LCRA have all published preventative actions that the 

public could take to minimize infections. These include avoiding swimming and jumping into 

freshwater during periods of high temperature and low water volume, minimizing forceful entry 

of water up the nasal passages during jumping or diving activities (i.e., by holding one’s nose or 

wearing nose plugs), and avoiding digging in or stirring up the sediment while swimming in 

shallow areas (CDC 2008b; LCRA 2007c; TDSHS 1995, 1997). 

As described in NUREG-1555, Environmental Standard Review Plan (NRC 2000), nuclear 

power plants that use cooling ponds, lakes, or canals and those that discharge to “small rivers” 

have a greater chance of affecting the public from increases in thermophilic microbial 

populations. A small river is defined as one with an average flow rate of less than 100,000 cfs. 

Based on the historical data for the years 1948 to 2004, the maximum annual average stream 

flow for the Colorado River at the Bay City streamflow gauging station above the STP site is 

14,270 cfs, the minimum annual average flow is 375 cfs, and the mean annual average flow is 
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NUREG-1937 5-72 February 2011 

approximately 2629 cfs (STPNOC 2010a). These flow rates meet the criterion in NUREG-1555 

for a small river. 

At Selkirk Island, above the MCR discharge point, water temperature in the Colorado River 

ranges from 43.5 to 92.1°F, with an average of 72.5°F (Section 2.3.3.1). While the average 

river water temperature is lower than the optimum temperature for growth of etiological agents 

(e.g., N. fowleri), the water temperature is warm enough to support these ubiquitous 

microorganisms (Wellings et al. 1977; TDSHS 1997; Ettinger et al. 2003). Section 5.2.3.1 

discusses the analysis by STPNOC and the review team of the thermal plume created by 

discharge from the MCR into the Colorado River. The maximum plume size evaluated was 

based on the greatest difference in temperatures between the MCR water and the river water 

(20.4°F). The conditions that create the maximum size of a thermal plume where the surface 

water would be elevated by 5°F above the ambient river water would cover the entire width of 

the river for a distance of about 4400 ft. However, under these conditions, the ambient river 

water temperature would be 55°F, which is too low for the optimum temperature for growth of 

the organisms that cause diseases in people. In addition, the water temperature is likely too 

cold for people in the region to swim and immerse themselves in the water. 

Recreational activities in the Colorado River within the vicinity of the STP site could expose 

people to etiological agents even during times when there is no discharge from the MCR 

because this segment of the river has been classified by TCEQ as impaired by presence of 

bacteria (TCEQ 2010b). However, the incidence of exposure leading to infection is low. For 

N. fowleri, the incidence of exposure is estimated at less than one in 100 million that a person 

exposed to water inhabited by N. fowleri would become infected (TDSHS 1995). As discussed 

in Section 2.10.1.3, outbreaks of other water-borne diseases in Texas are within the range of 

national trends in terms of cases per 100,000 population or total cases per year (TDSHS 2010). 

In the vicinity of the existing and proposed discharge structure, the Colorado River is used 

primarily by fisherman and boaters. Some boaters and owners of riverside houses use the river 

for swimming, water skiing, and other water sports (STPNOC 2008b). Opportunities for 

infection would be reduced if swimmers followed Federal and State recommendations for 

prevention of water-borne diseases (CDC 2008b; LCRA 2007c; TDSHS 1995, 1997). 

Furthermore, as discussed in Section 5.2, STPNOC evaluated the frequency of discharge from 

the MCR into the Colorado River based on operation of four units. The results of the 

simulations indicate that most of the discharge would take place during the first six months of 

any year, with the greatest frequency of discharge occurring in January and February. Since 

most recreational swimming takes place in the warmer months of the year, and incidences of 

PAM infections mostly occur in June through August, the likelihood that swimmers would 

become infected with N. fowleri from discharge water is diminished. 
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February 2011 5-73 NUREG-1937 

Based on the relatively low incidence of water-borne diseases from recreational activities in 

Texas (CDC 2009; TDSHS 2010), the infrequent discharge from the MCR into the Colorado 

River, and the small temperature increase expected as a result of discharging into the river, the 

review team concludes that potential impacts from etiological agents on human health would be 

minor and mitigation would not be warranted. 

5.8.2 Noise 

In NUREG-1437 (NRC 1996a), the NRC discusses the environmental impacts of noise from 

operations at existing nuclear power plants. Common sources of noise from plant operation 

include cooling towers, transformers, turbines, and the operation of pumps along with 

intermittent contributions from loud speakers and auxiliary equipment such as diesel generators. 

In addition, while there may be corona discharge noise associated with high-voltage 

transmission lines, the occurrences are infrequent and weather-related, when the public is likely 

to be indoors. The common sources of noise are discussed in this section. 

The landscape in the vicinity of the STP site is rural and flat. Approximately 67 percent of the 

land within the 6-mi vicinity of the STP site is agricultural land; 15 percent is forest land; 

11 percent is water; 1 percent is wetlands; 4 percent is rangeland, grassland, or bottomland; 

2 percent is urban; and less than 1 percent is barren land (see Figure 2-5). Two recreation 

areas are in the vicinity: the 7200-ac Mad Island WMA is located approximately 3 mi south of 

the STP site and the LCRA park approximately 3 mi east of the STP site (Section 2.2). Areas 

that are subject to farming are prone to seasonal noise-related events such as planting and 

harvesting. Wooded areas provide natural noise abatement control that reduces noise 

propagation. 

According to the STPNOC ER (2010a), noise from the operation of each cooling tower would be 

71 dBA 5 ft from the inlet and 51 dBA 400 ft from the inlet. Noise from the RMPF for four units 

is expected to be within the levels of the existing Units STP 1 and 2, which have generated no 

noise complaints (STPNOC 2010a). The nearest full-time residence is 1.5 mi west-southwest of 

the STP site. Relative to the location of the nearest full-time residence, proposed Units 3 and 4 

cooling towers would be located 0.6 mi (approximately 3200 ft) from the site boundary. 

Distance and vegetation would significantly attenuate any noise. Noise levels at the site 

boundary are expected to be below the 60-65 dBA level that NRC considers significant (NRC 

1996a). 

STPNOC assumes that the noise from existing STP Units 1 and 2 is not greater than the normal 

operations noise occurring at other nuclear power plants and could be used as the basis for 

evaluating impacts for proposed Units 3 and 4 (STPNOC 2010a). With the exceptions of the 

public address system and when the emergency sirens are tested, which are both relatively 

short-lived occurrences, the noise level at the STP site boundary is likely to be less than 

background. Intermittently operated equipment (e.g., emergency diesel generators, combustion 
Operational Impacts at the Proposed Site 

NUREG-1937 5-74 February 2011 

turbine generators) are equipped with mufflers to reduce exhaust noise. As discussed above, 

no public roads, public buildings, or residences are located within the EAB. Planned revegetation of areas previously disturbed while building Units 3 and 4 at STP would provide an 

additional buffer for operations-related noise (STPNOC 2010a). Background or ambient sound 

levels at the STP site, considering the local environment, are comparable to the ambient sound 

level of a farm, which is approximately 44 dBA, or to that of a small town or quiet suburban area, 

around 46 to 52 dBA. To put these noise levels in context, normal conversation is 50 to 60 dBA 

(EPA 1974). 

According to NUREG-1437 (NRC 1996a), noise levels below 60 to 65 dBA are considered to be 

of small significance. More recently, the impacts of noise were considered in the Generic 

Environmental Impact Statement on Decommissioning of Nuclear Facilities (NUREG-0586, 

Supplement 1) (NRC 2002). The criterion for assessing the level of significance was not 

expressed in terms of sound levels, but was based on the effect of noise on human activities 

and on threatened and endangered species. The criterion in NUREG-0586, Supplement 1, is 

stated as follows: 

The noise impacts... are considered detectable if sound levels are sufficiently high to 

disrupt normal human activities on a regular basis. The noise impacts... are considered 

destabilizing if sound levels are sufficiently high that the affected area is essentially 

unsuitable for normal human activities, or if the behavior or breeding of a threatened and 

endangered species is affected. 

Based on the relatively low levels of noise associated with the operation of the proposed Units 

3 and 4 and the significant attenuation of that noise, the review team concludes that potential 

noise impacts associated with the operation of the new units on the public would be minor and 

would not require mitigation. 

5.8.3 Acute Effects of Electromagnetic Fields 

Electric shock resulting from either direct access to energized conductors or induced charges in 

metallic structures is an example of an acute effect from EMF associated with transmission lines 

(NRC 1999). Such acute effects are controlled and minimized by conformance with National 

Electrical Safety Code (NESC) criteria and adherence to the standards for transmission systems 

regulated by the Public Utility Commission of Texas (PUCT). 

As discussed in Section 3.2.2.3, the transmission system activities specifically for operation of 

Units 3 and 4 would principally involve installation activities on the STP site. Other activities 

include upgrades to existing offsite systems that are owned and operated by other companies. 

In the ER, STPNOC evaluated the proposed Units 3 and 4 transmission systems acute effects 

of EMF (STPNOC 2010a). AEP and CenterPoint Energy, which are transmission server 

providers and owners of the affected transmission lines, would be responsible for any upgrades 
 Operational Impacts at the Proposed Site 

February 2011 5-75 NUREG-1937 

to the transmission lines. AEP planned to replace some of the towers and conductors along the 

STP-to-Hillje ROW by addressing line sag clearances to conform to NESC standards, and 

consequently, to prevent electrical shock. STPNOC states that all existing 345-kV transmission 

lines use steel towers designed to provide clearances consistent with the NESC. The ER 

further states that STPNOC anticipates that transmission service providers would construct lines 

in the future with clearances consistent with the NESC. Clearances for new above grade highvoltage conductors would be expected to be equal to or exceed existing clearances.

Based on the PUCT regulations related to the design and installation of new transmission lines, 

and that transmission lines constructed and upgraded to serve proposed Units 3 and 4 would 

meet NESC standards in effect at the time of installation, the review team concludes that the 

potential impact to the public from acute effects of EMF would be minor and further mitigation 

would not be warranted. 

5.8.4 Chronic Effects of Electromagnetic Fields 

Operating power transmission lines in the United States produce EMF of nonionizing radiation 

at 60 Hz, which is considered to be an ELF EMF. Research on the potential for chronic effects 

of EMF from energized transmission lines was reviewed and addressed by the NRC in 

NUREG-1437 (NRC 1996a). At that time, research results were not conclusive. The National 

Institute of Environmental Health Sciences (NIEHS) directs related research through the 

U.S. Department of Energy. An NIEHS report (NIEHS 1999; AGNIR 2006) contains the 

following conclusion: 

The NIEHS concludes that ELF-EMF exposure cannot be recognized as entirely safe 

because of weak scientific evidence that exposure may pose a leukemia hazard. In our 

opinion, this finding is insufficient to warrant aggressive regulatory concern. However, 

because virtually everyone in the United States uses electricity and therefore is routinely 

exposed to ELF-EMF, passive regulatory action is warranted such as a continued emphasis 

on educating both the public and the regulated community on means aimed at reducing 

exposures. The NIEHS does not believe that other cancers or non-cancer health outcomes 

provide sufficient evidence of a risk to currently warrant concern. 

The review team reviewed available scientific literature on chronic effects to human health from 

ELF-EMF published since the NIEHS report, and found that several other organizations reached 

the same conclusions (AGNIR 2006; WHO 2007). Additional work under the auspices of the 

World Health Organization (WHO) updated the assessments of a number of scientific groups 

reflecting the potential for transmission line EMF to cause adverse health impacts in humans. 

The monograph summarized the potential for ELF-EMF to cause disease such as cancers in 

children and adults, depression, suicide, reproductive dysfunction, developmental disorders, 

immunological modifications, and neurological disease. The results of the review by WHO 
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NUREG-1937 5-76 February 2011 

(2007) found that the extent of scientific evidence linking these diseases to EMF exposure is not 

conclusive. 

The review team reviewed available scientific literature on chronic effects of EMF on human 

health and found that the scientific evidence regarding the chronic effects of ELF-EMF on 

human health does not conclusively link ELF-EMF to adverse health impacts. 

5.8.5 Occupational Health 

As discussed in Section 2.10, human health risks for personnel engaged in activities such as 

maintenance, testing, and plant modifications for Units 3 and 4 are expected to be dominated by 

occupational accidents (e.g., falls, electric shock, burns) or occupational illnesses due to noise 

exposure, exposure to toxic or oxygen-replacing gases, and other hazards. The 2007 annual 

incidence rates (the number of injuries and illnesses per 100 full-time workers) for the State of 

Texas and the United States for electric power generation, transmission and distribution workers 

are 3.1 and 3.6, respectively (BLS 2008a, b). The 2007 annual incidence rate (the number of 

injuries and illnesses per 100 full-time workers) in the United States for nuclear electric power 

generation workers is 0.9 (BLS 2008b). Historically, actual injury and fatality rates at STPNOC 

facilities have been lower than the average U.S. industrial rates, with a 2002 through 2006 

average incidence rate of 0.6 per hundred workers (STPNOC 2010a). 

In its ER, STPNOC addresses management of occupational injury and fatality risks through 

safety and health programs, and personnel to promote safe work practices and respond to 

occupational injuries and illnesses (STPNOC 2010a). Procedures have been developed and 

implemented for the existing units that would be applied to the proposed new units that have the 

objective of providing personnel who work at STP with an effective means of preventing 

accidents due to unsafe conditions and unsafe acts. These safe work practices address a 

number of occupational health issues (e.g., hearing protection, confined space entry, personal 

protective equipment, heat stress, electrical safety, the safe use of ladders, chemical handling, 

storage, and use, and other industrial hazards). These procedures ensure that STPNOC 

adheres to NRC and Occupational Safety and Health Administration (OSHA) safety standards 

(29 CFR Part 1910), practices, and procedures. Furthermore, health impacts to workers from 

nonradiological emissions during operations at the proposed Units 3 and 4 would be monitored 

and controlled in accordance with the applicable OSHA regulations. Appropriate State and local 

statutes would also be considered when assessing the occupational hazards and health risks 

for new nuclear unit operation. 

Based on mitigation measures identified by STPNOC in its ER, strict adherence to NRC and 

OSHA safety standards, practices, and procedures, and the review team’s independent 

evaluation, the review team concludes that occupational health impacts to STP onsite personnel 

would be minimal and no further mitigation would be warranted. 
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February 2011 5-77 NUREG-1937 

5.8.6 Impacts of Transporting Operations Personnel to the Proposed Site 

This EIS assesses the impact of transporting workers to and from the STP site from the 

perspective of three areas of impact: the socioeconomic impacts, the air quality impacts of 

fugitive dust and particulate matter emitted by vehicle traffic, and the potential health impacts 

due to additional traffic-related accidents. Human health impacts are addressed in this section, 

while the socioeconomic impacts are addressed in Section 5.4.1.3, and air quality impacts are 

addressed in Section 5.7.1. 

The general approach used to calculate nonradiological impacts of fuel and waste shipments is 

the same as that used to calculate the impacts of transporting operations and outage personnel 

to and from the proposed STP site and alternative sites (see Section 4.8.3). However, 

preliminary estimates are the only data available to estimate these impacts. The impacts 

evaluated in this section for two new nuclear generating units at the STP site are appropriate to 

characterize the alternative sites discussed in Section 9.3. Alternative sites evaluated in this 

EIS include the existing STP site (proposed), and alternative sites at Allens Creek, Red 2, and 

Trinity 2. There is no meaningful differentiation among the proposed and the alternative sites 

regarding the nonradiological environmental impacts from transporting operations and outage 

personnel to the STP site and alternative sites and are not discussed further in Chapter 9. 

The assumptions made by the review team to provide reasonable estimates of the parameters 

needed to calculate nonradiological impacts are listed below. 

• In its ER, STPNOC stated that 959 workers would be needed for operation of proposed 

Units 3 and 4 (STPNOC 2010a). The review team assumed that one-half of the operations 

workers would be assigned to each unit so the operations work force used in the 

calculations was 480 workers per unit. An additional 1500 to 2000 temporary workers are 

estimated to be needed for refueling outages (STPNOC 2010a). The review team assumed 

that outages for the two units would not occur simultaneously. 

• The average commuting distance for operations and outage workers was assumed by the 

review team to be 20 mi one-way. This assumption is based on the U.S. Department of 

Transportation (DOT) data that estimates the typical commute is approximately 16 mi one 

way (DOT 2003). 

• To develop representative commuter traffic impacts, data from the U.S. Department of 

Transportation provide a Texas-specific fatality rate for all traffic for the years from 2003 to 

2007 (DOT 2009a). The average fatality rate for the period from 2003 to 2007 in Texas was 

used as the basis for estimating Texas-specific injury and accident rates. Adjustment factors 

were developed using national traffic accident statistics in the DOT publication National 

Transportation Statistics 2007 (DOT 2007). The adjustment factors are the ratio of the 

national injury rate to the national fatality rate and the ratio of the national accident rate to the 
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NUREG-1937 5-78 February 2011 

national fatality rate. These adjustment factors were multiplied by the Texas-specific fatality 

rate to approximate the injury and accident rates for commuters in the State of Texas. 

The estimated impacts of transporting operations and outage workers to and from the proposed 

STP site and alternative sites are listed in Table 5-8. The total annual traffic fatalities during 

operations, including both operations and outage personnel, represent about a 1.4 percent 

increase above the average 7.4 traffic fatalities per year that occurred in Matagorda County, 

Texas, from 2004 to 2008 (DOT 2009b). The impacts of transporting operations workers to and 

from the alternative sites were about a 0.9 percent increase for the Trinity 2 site and 1 percent 

increases for the Allens Creek and Red 2 sites. These percentages represent small increases 

relative to the current traffic fatality risks in the areas surrounding the proposed STP site and 

alternative sites. 

Table 5-8. Nonradiological Estimated Impacts of Transporting Operations Workers to and from 

the STP Site 

Accidents Per 

Year Per Unit

Injuries Per 

Year Per Unit

Fatalities Per 

Year Per Unit

Permanent Workers 9.4 × 100 4.3 × 100 6.4 × 10−2

Outage Workers 4.7 × 100 2.2 × 100 3.2 × 10−2

Based on the information provided by STPNOC, the review team’s independent evaluation, and 

considering that this increase would be small relative to the current traffic fatalities (i.e., before 

the proposed units are constructed) in the affected counties, the review team concludes that the 

nonradiological impacts of transporting construction materials and personnel to the proposed 

STP site would be minimal, and mitigation would not be warranted. 

5.8.7 Summary of Nonradiological Health Impacts 

The review team evaluated health impacts to the public and workers from the proposed cooling 

system, noise generated by plant operations, acute and chronic impacts of EMFs, and 

transporting operations and outage workers to and from the proposed Units 3 and 4. Health 

risks to workers are expected to be dominated by occupational injuries at rates below the 

average U.S. industrial rates. Health impacts to the public and workers from etiological agents, 

noise generated by plant operations, and acute impacts of EMF would be minimal. The review 

team reviewed available scientific literature on chronic effects of EMF on human health and 

found that the scientific evidence regarding the chronic effects of ELF-EMF on human health 

does not conclusively link ELF-EMF to adverse health impacts. Based on the information 

provided by STPNOC and the review team’s own independent evaluation, the review team 

concludes that the potential impacts to nonradiological health resulting from the operation of the 
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February 2011 5-79 NUREG-1937 

proposed two additional units at the STP site would be SMALL and mitigation would not be 

warranted. 

5.9 Radiological Impacts of Normal Operations 

This section addresses the radiological impacts of normal operations of the proposed two new 

units on the STP site, including a discussion of the estimated radiological doses to a member of 

the public and to biota inhabiting the area around the STP site. Estimated doses to workers at 

the proposed units are also discussed. Radiological impacts were determined using the 

Advanced Boiling Water Reactor (ABWR) design with expected direct radiation and liquid and 

gaseous radiological effluent rates in the evaluation (see Section 3.4.3). 

The General Electric (GE) ABWR is proposed as the technology for the new Units 3 and 4 at the 

STP site. The NRC approved the reference ABWR Design Control Document (DCD) in March 

1997. The final design certification rule was published in the Federal Register on May 12, 1997 

(62 FR 25800). This certification allows the ABWR design to be referenced under 10 CFR Part 

52; therefore, the evaluation of radiological impacts of normal operations presented here is 

based on the source term from the DCD (GE 1997). 

5.9.1 Exposure Pathways 

The public and biota would receive radiation dose from a nuclear unit via the liquid effluent, 

gaseous effluent and direct radiation pathways. STPNOC estimated the potential exposures to 

the public and biota by evaluating exposure pathways typical of those surrounding a nuclear unit 

at the STP site. STPNOC considered pathways that could cause the highest calculated 

radiological dose based on the use of the environment by the residents located around the site 

(STPNOC 2010a). For example, factors such as the location of homes in the area, 

consumption of meat from the area, and consumption of vegetables grown in area gardens 

were considered. 

For the liquid effluent release pathway, STPNOC considered the following exposure pathways 

in evaluating the doses to the maximally exposed individual (MEI): ingestion of aquatic food 

(i.e., fish and invertebrates), direct radiation exposure from shoreline activities, and swimming 

and boating exposure. The water downstream of proposed Units 3 and 4 is neither used for 

irrigation nor as a source of drinking water. Liquid effluents are released to the MCR. Seepage 

from the MCR (Section 2.3.3.2) would result in releases of radiological materials to groundwater 

and surface water pathways. 

The design of proposed STP Units 3 and 4 includes a number of features to prevent and 

mitigate leakage from system components such as pipes and tanks that may contain radioactive 

material (STPNOC 2010c). In addition, STPNOC committed to use the guidance of NEI 08-08, 

"Generic FSAR Template Guidance for Life-Cycle Minimization of Contamination," to the extent 
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NUREG-1937 5-80 February 2011 

practicable in the development of operating programs and procedures (STPNOC 2009h). 

However, the potential still exists for leaks of radioactive material, such as tritium, into the 

ground, similar to those that have been reported at currently operating power plants. Based on 

the discussion above, the NRC staff expects that the impacts from such potential leakage for 

proposed STP Units 3 and 4 would be small. 

For the gaseous effluent release pathway, STPNOC considered the following pathways in 

evaluating the dose to the MEI: immersion in the radiological plume, direct radiation exposure 

from deposited radioactivity, inhalation, ingestion of garden fruit and vegetables, and ingestion 

of beef. Milk consumption was not considered because no milk animals are located within 5 mi 

of the site. 

STPNOC (STPNOC 2010a) stated that direct radiation from the Units 3 and 4 reactor buildings 

and planned Onsite Staging Facility likely would be the primary source of exposure to the public 

from the STP site. STPNOC (2010a) stated the primary objective of radiation shielding is to 

protect operating personnel and the general public from radiation emanating from the reactor, 

power conversion systems, radwaste process systems, and auxiliary systems. However, 

STPNOC assumes that the direct radiation from normal operation of proposed Units 3 and 4 

would result in 2.5 mrem/yr per unit at the EAB, based on the plant shielding design acceptance 

criteria for the ABWR due to direct and scattered radiation. 

STPNOC (2010a) calculated population doses using the same exposure pathways as used for 

the individual dose assessment, but included ingestion of invertebrates caught in Matagorda 

Bay (see Figure 5-1) in the liquid pathways and ingestion of milk in the gaseous pathways. 

Exposure pathways considered in evaluating dose to the biota are shown in Figure 5-2 and 

included: 

• Ingestion of aquatic foods 

• Ingestion of water 

• External exposure from water immersion or shoreline sediments 

• Inhalation of airborne radionuclides 

• External exposure to immersion in gaseous effluent plumes 

• Surface exposure from deposition of iodine and particulates from gaseous effluents 

(NRC 1977). 

The NRC staff reviewed the exposure pathways for the public and biota identified by STPNOC 

and found them to be appropriate, based on a documentation review, a tour of the environs, and 

interviews with STPNOC staff and contractors during the site visit in February 2008. 
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February 2011 5-81 NUREG-1937 

Figure 5-1. Exposure Pathways to Man (adapted from Soldat et al. 1974)
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NUREG-1937 5-82 February 2011 

Figure 5-2. Exposure Pathways to Biota Other Than Man (adapted from Soldat et al. 1974)
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February 2011 5-83 NUREG-1937 

5.9.2 Radiation Doses to Members of the Public 

STPNOC calculated the dose to the MEI and the population living within a 50-mi radius of the 

site from the direct radiation, liquid, and gaseous effluent release pathways (STPNOC 2010a). 

STPNOC stated that it conservatively estimated the direct radiation exposure to the MEI from 

sources of radiation at the proposed Units 3 and 4 would be 2.5 mrem per year per unit. 

5.9.2.1 Liquid Effluent Pathway 

Liquid effluents are released into the MCR. The highest concentration of the radiological 

material would be in the MCR. Water seeps out of the MCR into the groundwater underlying the 

MCR. As this water moves away from the MCR the concentration of radiological material 

diminishes due to dispersion and radiological decay. A series of 770 pressure relief wells drain 

water from the Upper Shallow Aquifer underlying the MCR into drainage ditches. The drainage 

ditches on the west side of the MCR flow into the Little Robbins Slough, which empties into the 

Colorado River. The drainage ditches on the east side of the MCR flow into the Colorado River. 

The remainder of water not collected by the relief wells follows the groundwater gradient and 

discharges into the Colorado River. The Colorado River flows into Matagorda Bay. There are 

private wells that pump non-potable water from the Upper Shallow Aquifer between the MCR 

and the Colorado River. The owners of these wells use the groundwater to provide water for 

livestock (STPNOC 2010a). Liquid pathway doses to the MEI were calculated by STPNOC 

using the LADTAP II computer program (Strenge et al. 1986). The following activities were 

considered in the STPNOC dose calculations: fish and invertebrate consumption, and 

swimming, boating and shoreline exposure (STPNOC 2010a). NRC staff added the meat cow 

pathway from livestock drinking water from groundwater wells. 

The liquid effluent releases used in the estimates of dose are found in Table 3.5-1 of the ER 

(STPNOC 2010a). Other parameters used as inputs to the LADTAP II program include effluent 

discharge rate, dilution factor for discharge, transit time to receptor, and liquid pathway 

consumption and usage factors (i.e., fish consumption). For the meat cow pathway, NRC staff 

used the beef consumption parameters reported in Appendix G and calculated an estimate of 

tritium in a beef cow drinking well water. 

STPNOC calculated liquid pathway doses to the MEI as shown in ER Table 5.4-5. The 

representative MEI was a teenager ingesting fresh water sport fish, and receiving shoreline 

exposure from Little Robbins Slough for total body and all other organs except bone. For dose 

to bone, the MEI was a child at the same location (STPNOC 2010a). Table 5-9 also includes 

doses for the meat cow pathway as calculated by NRC staff. 

The NRC staff recognizes the LADTAP II computer program as an appropriate method for 

calculating dose to the MEI for liquid effluent releases. The NRC staff concluded that all the 

input parameters used in the STPNOC calculations were appropriate. The NRC staff performed 
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NUREG-1937 5-84 February 2011 

an independent evaluation of the liquid pathway doses using input parameters from the ER and 

found similar results. Results of the NRC staff’s independent review are found in Appendix G. 

Table 5-9. Annual Doses to the MEI for Liquid Effluent Releases from a New Unit 

Pathway Age Group 

Total Body 

(mrem/yr) 

Maximum Organ 

(Bone)

(mrem/yr) 

Thyroid 

(mrem/yr) 

Fish and Other Organisms Adult 0.00009 0.0008 0.00003 

Teen 0.00008 0.0009 0.00002 

Child 0.00009 0.0011 0.00002 

Meat Cow Adult 0.0037 0.0037 0.0037 

Teen 0.0022 0.0022 0.0022 

Child 0.0026 0.0026 0.0026 

Direct Radiation Adult 0.00003 0.00003 0.00003 

Teen 0.0002 0.0002 0.0002 

Child 0.00004 0.00004 0.00004 

5.9.2.2 Gaseous Effluent Pathway 

Gaseous pathway doses to the MEI were calculated by STPNOC using the GASPAR II 

computer program (Strenge et al. 1987) at the nearest residence, the EAB, the nearest garden 

and meat cow. The following activities were considered in the dose calculations: (1) direct 

radiation from immersion in the gaseous effluent cloud and from particulates deposited on the 

ground; (2) inhalation of gases and particulates; (3) ingestion of meat from animals eating 

contaminated grass; and (4) ingestion of garden vegetables contaminated by gases and 

particulates. STPNOC (2010a) states that no milk cows or milk goats are located within 5 mi of 

the proposed site; therefore, milk ingestion was not considered as a dose pathway for the MEI. 

The gaseous effluent releases used in the estimate of dose to the MEI and population are found 

in Table 3.5-2 of the ER (STPNOC 2010a) and Table G-4 of Appendix G. Other parameters 

used as inputs to the GASPAR II program, including population data, atmospheric dispersion 

factors, ground deposition factors, receptor locations, and consumption factors, are found in 

Tables 5.4-2, 5.4-3 and 5.4-4 of the ER (STPNOC 2010a). Gaseous pathway doses to the MEI 

calculated by STPNOC are found in Table 5.4-6 of the ER (STPNOC 2010a). STPNOC 

assumed the MEI was a child located 2.18 mi WSW from the proposed units except for the 

thyroid doses; the MEI for thyroid doses was a child located 3.03 mi NNW from the proposed 

units. Gaseous pathway doses for a single unit are shown in Table 5-10. 
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February 2011 5-85 NUREG-1937 

The NRC staff recognizes the GASPAR II computer program as an appropriate tool for 

calculating dose to the MEI and population from gaseous effluent releases. The NRC staff 

reviewed the input parameters and values used by STPNOC (STPNOC 2010a) and concluded 

that the parameters used by STPNOC were appropriate. The NRC staff performed an 

independent evaluation of the gaseous pathway doses and obtained similar results for the MEI. 

Results of the NRC staff’s independent review are found in Appendix G. 

Table 5-10. Annual Doses to MEI for Gaseous Effluent Releases from a New Unit 

Pathway Age Group 

Total Body Dose 

(mrem/yr) 

Max Organ 

(Bone) 

(mrem/yr) 

Skin Dose 

(mrem/yr) 

Thyroid 

Dose(a)

(mrem/yr) 

Plume 

(2.18 mi WSW) 

All 0.167 0.167 0.462 0.087 

Ground 

(2.18 mi WSW) 

All 0.0236 0.0236 0.0277 0.0283 

Inhalation 

(2.18 mi WSW) 

Adult 

Teen 

Child 

Infant 

0.00162 

0.00175 

0.00167 

0.00104 

0.000815 

0.00113 

0.00151 

0.00113 

0.00103 

0.00104 

0.00092 

0.00053 

0.0745 

0.0975 

0.121 

0.110 

Vegetable(b) 

(2.18 mi WSW) 

Adult 

Teen 

Child 

0.0409 

0.0615 

0.138 

0.176 

0.284 

0.68 

0.00335 

0.054 

0.129 

0.83 

1.055 

1.99 

Meat(b) 

(2.18 mi WSW) 

Adult 

Teen 

Child 

0.0133 

0.0109 

0.0200 

0.0615 

0.052 

0.098 

0.0123 

0.0135 

0.0194 

0.0399 

0.0297 

0.0467 

(a) MEI was located 2.18 mi WSW of new units except for thyroid; MEI for thyroid was located 3.03 mi NNW of new 

units. 

(b) No infant doses were calculated for the vegetable and meat pathway because the doses that infants receive 

from this diet would be bounded by the dose calculated for the child. 

5.9.3 Impacts to Members of the Public 

This section describes the NRC staff’s evaluation of the estimated impacts from radiological 

releases and direct radiation of the proposed two new units at the STP site. The evaluation 

addresses dose from operations to the MEl located at the STP site and the population dose 

(collective dose to the population within 50 mi) around the STP site. 

5.9.3.1 Maximally Exposed Individual 

STPNOC (2010a) stated that total body and organ dose estimates to the MEI from liquid and 

gaseous effluents for each new unit would be within the dose design objectives of 10 CFR 

Part 50, Appendix I. STPNOC determined the total body and maximum organ doses at the 

Little Robbins Slough from liquid effluents were well within the respective 3 mrem/yr and 
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NUREG-1937 5-86 February 2011 

10 mrem/yr Appendix I dose design objectives. Doses at the site boundary from gaseous 

effluents were well within the Appendix I dose design objectives of 10 mrad/yr air dose from 

gamma radiation, 20 mrad/yr air dose from beta radiation, 5 mrem/yr to the total body, and 

15 mrem/yr to the skin. In addition, dose to the thyroid was within the 15 mrem/yr Appendix I 

dose design objective. A comparison of dose estimates for each new unit to the Appendix I 

dose design objectives is found in Table 5-11. The NRC staff completed an independent 

evaluation of compliance with Appendix I dose design objectives and found similar results, as 

shown in Appendix G. Adding doses to an individual from consumption of beef from a cow 

consuming water containing tritium from a nearby well does not change the conclusions. 

Table 5-12 on the following page compares the combined dose estimates from direct radiation 

and gaseous and liquid effluents from existing Units 1 and 2 and the proposed Units 3 and 4 

against the 40 CFR Part 190 standards (STPNOC 2010a). The table shows that the total doses 

to the MEI from liquid and gaseous effluent as well as direct radiation at the STP site are well 

below the 40 CFR Part 190 standards. The total body and organ dose estimates to the MEI 

from liquid and gaseous effluents for STP Units 1 and 2 would be less than the estimates from 

Units 3 and 4, which are well within the design objectives of 10 CFR Part 50, Appendix I. 

Section 4.9 states that the direct radiation doses from the existing STP site do not vary 

significantly from background radiation levels at the site boundary; therefore, direct radiation 

from the existing units is not included in Table 5-12. The NRC staff completed an independent 

evaluation of compliance with 40 CFR 190 standards and found similar results. The results of 

staff’s evaluation are presented in Appendix G. 

Table 5-11. Comparison of Annual MEI Dose Rates for a Single Unit with 10 CFR 50, 

Appendix I Design Objectives 

Pathway/Type of Dose STPNOC (2010a) 

Appendix I Design 

Objectives 

Liquid Effluents 

Total Body 0.00026(a) 3 mrem/yr 

Maximum Organ Dose (Bone) 0.0012(b) 10 mrem/yr 

Gaseous Effluent(c)

 (Noble Gases Only) 

Gamma Air Dose 3.3 10 mrad/yr 

Beta Air Dose 4.3 20 mrad/yr 

Total Body Dose 3.2 5 mrem/yr 

Skin Dose 7.3 15 mrem/yr 

Gaseous Effluents (Radioiodines and Particulates) 

Maximum Organ Dose (Thyroid) 2.2(d) 15 mrem/yr 

Source: STPNOC 2010a 

(a) Teenager using Little Robbins Slough. 

(b) Child using Little Robbins Slough. 

(c) North-northwest site boundary. 

(d) Child eating home grown meat and vegetables. 
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February 2011 5-87 NUREG-1937 

Table 5-12. Comparison of MEI Annual Doses with 40 CFR Part 190 Standards (mrem/yr) 

STP 1 and 2 (Existing)(a) STP 3 and 4 (ABWR)

Site 

Total

Regulatory 

Standard

Liquid Gaseous Total 

Direct 

Radiation Liquid(b) Gaseous Total 

Total 

Body 

0.0042 0.0080 0.012 5.0 0.00053 0.70(c) 5.70 5.71 25 

Thyroid 0.0041 0.0097 0.014 NA(e) 0.00041 4.54(d) 4.54 4.55 75 

Other 

Organ - 

bone 

0.00077 0.0011 0.0019 NA 0.0023 1.94(c)

 1.94 1.94 25 

Source: STPNOC 2010a 

(a) Same receptors as proposed Units 3 and 4 at STP. 

(b) Teen using Little Robbins Slough for shoreline activities and fishing, except bone dose, which is for child at same 

location. 

(c) Residence with meat animal and vegetable garden, dose to child, 2.18 mi WSW of new units (MEI). 

(d) Residence with meat animal and vegetable garden, dose to child, 3.03 mi NNW of new units (MEI). 

(e) NA = Not Applicable 

5.9.3.2 Population Dose 

STPNOC estimates the collective total body dose within a 50-mi radius of the STP site would be 

0.58 person-rem/yr from the proposed Units 3 and 4 from gaseous and liquid effluent pathways 

(STPNOC 2010a). The estimated collective dose to the same population from background 

radiation is estimated to be 160,000 person-rem/yr. The dose from natural background 

radiation was calculated by multiplying the 50-mi population estimate for 2060 of approximately 

514,000 people (STPNOC 2010a) by the annual U.S. average background dose rate of 311 

mrem/yr (NCRP 2009). 

Collective population doses from gaseous and liquid effluent pathways were estimated by 

STPNOC using GASPAR II and LADTAP II computer codes, respectively. The NRC staff 

performed an independent evaluation of population doses and obtained similar results (see 

Appendix G). 

Radiation protection experts assume that any amount of radiation may pose some risk of 

causing cancer or a severe hereditary effect, and that the risk is higher for higher radiation 

exposures. Therefore, a linear, no-threshold dose response relationship is used to describe the 

relationship between radiation dose and detriments such as cancer induction. A recent report 

by the National Research Council (2006), the Biological Effects of Ionizing Radiation (BEIR) VII 

report, uses the linear, no-threshold model as a basis for estimating the risks from low doses. 

This approach is accepted by NRC as a conservative method for estimating health risks from 

radiation exposure, recognizing that the model may overestimate those risks. Based on this 

method, the NRC staff estimated the risk to the public from radiation exposure using the 
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NUREG-1937 5-88 February 2011 

nominal probability coefficient for total detriment. This coefficient has the value of 570 fatal 

cancers, nonfatal cancers, and severe hereditary effects per 1,000,000 person-rem 

(10,000 person-Sieverts), equal to 0.00057 effects per person-rem. The coefficient is taken 

from International Commission on Radiological Protection (ICRP) Publication 103 (ICRP 2007). 

The estimated collective whole body dose to the population living within 50 mi of the proposed 

two new units at the STP site is 0.583 person-rem/yr (STPNOC 2010a), which is less than the 

1754 person-rem/yr value that ICRP and National Council on Radiological Protection and 

Measurements (NCRP) suggest would most likely result in zero excess health effects (NCRP 

1995; ICRP 2007). 

In addition, at the request of the U.S. Congress, the National Cancer Institute (NCI) conducted a 

study and published, "Cancer in Populations Living Near Nuclear Facilities," in 1990 (NCI 1990). 

This report included an evaluation of health statistics around all nuclear power plants, as well as 

several other nuclear fuel cycle facilities, in operation in the United States in 1981 and found "no 

evidence that an excess occurrence of cancer has resulted from living near nuclear facilities" 

(NCI 1990). 

5.9.3.3 Summary of Radiological Impacts to Members of the Public 

The health impacts from routine gaseous and liquid radiological effluent releases from the two 

proposed units have been calculated by both STPNOC and NRC staff. Based on information 

provided by STPNOC, and the NRC’s evaluation, the NRC staff concludes there would be no 

observable health impacts to the public from normal operations of the proposed units; the health 

impact would be SMALL and additional mitigation would not be warranted. 

5.9.4 Occupational Doses to Workers 

STPNOC (2010a) reported annual occupational dose estimates of about 248 person-rem for 

existing STP Units 1 and 2 during 2005. Based on available data for the ABWR design, the 

projected annual occupational dose, including outages, is estimated to be 91 person-rem for 

each unit or 182 person-rem for both units (STPNOC 2010a). The estimated occupational 

doses for ABWR designs are estimated to be less than the annual average occupational doses 

for current light-water reactors. 

The licensee of a new plant would need to maintain individual doses to workers within 5 rem 

annually as specified in 10 CFR 20.1201 and incorporate provisions to maintain doses as low as 

is reasonably achievable (ALARA). 

The NRC staff concludes that the health impacts from occupational radiation exposure would be 

SMALL based on individual worker doses being maintained within 10 CFR 20.1201 limits and 

collective occupational doses being typical of doses found in current operating light-water 
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February 2011 5-89 NUREG-1937 

reactors. Additional mitigation would not be warranted because the operating plant would be 

required to maintain doses ALARA. 

5.9.5 Doses to Biota Other than Humans 

STPNOC estimated doses to biota in the site environs; in many cases using surrogate species. 

Surrogate species used in the ER are well defined and provide an acceptable method for 

evaluating doses to biota (Soldat et al. 1974). Surrogate species analysis was performed for 

aquatic species such as fish, invertebrates, and algae; and for terrestrial species such as 

muskrats, raccoons, herons, and ducks. Important biota species for the STP site (see Section 

2.4.1) and the corresponding surrogate species are as follows: (1) grass shrimp, crayfish, and 

blue crab – invertebrates; (2) darter, shiner, and largemouth bass, – fish; (3) white-tailed deer, 

gray and fox squirrels – raccoon and muskrat; (4) wood storks, coots, teal, and shovellers – 

duck; and (5) whooping crane – heron. Exposure pathways considered in evaluating dose to the 

biota were discussed in Section 5.9.1 and shown in Figure 5-2. 

5.9.5.1 Liquid Effluent Pathway 

Liquid effluents are released into the MCR. The highest concentration of the radiological 

material would be in the MCR. Water seeps out of the MCR into the groundwater underlying the 

MCR. As this water moves away from the MCR the concentration of radiological material 

diminishes due to dispersion and radiological decay. A series of 770 pressure relief wells drain 

water from the Upper Shallow Aquifer underlying the MCR into drainage ditches. The drainage 

ditches on the west side of the MCR flow into the Little Robbins Slough, which empties into the 

Colorado River. The drainage ditches on the east side of the MCR flow into the Colorado River. 

The remainder of water not collected by the relief wells follows the groundwater gradient and 

discharges into the Colorado River. The Colorado River flows into Matagorda Bay (STPNOC 

2010a). 

STPNOC (2010a) used the LADTAP II computer program to calculate doses to the biota from 

the liquid effluent pathway. Liquid pathway doses were higher for biota compared to humans 

because of considerations for bioaccumulation of radionuclides, ingestion of aquatic plants, 

ingestion of invertebrates, and increased time spent in water and shoreline compared to 

humans. The liquid effluent releases used in estimating biota dose are found in Table 3.5-1 of 

the ER (STPNOC 2010a). STPNOC evaluated biota doses in Little Robbins Slough (STPNOC 

2010a) and in the MCR (STPNOC 2009f). Table 5-13 presents STPNOC’s estimates of the 

doses to biota from the liquid and gaseous pathways from proposed Units 3 and 4. Doses from 

liquid effluents at other locations such as Little Robbins Slough would be lower. As discussed in 

Appendix G, the NRC staff obtained similar results in confirmatory calculations for the liquid 

pathway. 
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Table 5-13. Biota Doses for Proposed Units 3 and 4

Biota 

STPNOC Biota Dose Estimates 

Liquid 

Pathway(a) 

(mrad/yr) 

Gaseous 

Pathway(b) 

(mrad/yr) 

Total 

(mrad/yr) 

Fish 2.50 0 2.50 

Invertebrate 5.30 0 5.30 

Algae 0.54 0 0.54 

Muskrat 2.44 8.45 10.89 

Raccoon 1.38 9.96 11.34 

Heron 2.46 8.45 10.91 

Duck 3.15 9.96 13.11 

(a) Using MCR water 

(b) Maximum site boundary 

5.9.5.2 Gaseous Effluent Pathway 

Gaseous effluents would contribute to the total body dose of the terrestrial surrogate species 

(i.e., muskrat, raccoon, heron, and duck). The exposure pathways include inhalation of airborne 

radionuclides, external exposure because of immersion in gaseous effluent plumes, and surface 

exposure from deposition of iodine and particulates from gaseous effluents (Figure 5-2). The 

dose calculated to the MEI from gaseous effluent releases in Table 5-10 would also be 

applicable to terrestrial surrogate species with two modifications. One modification defined in 

STPNOC’s ER (2010a) was increasing the ground deposition factors by a factor of two as 

terrestrial animals would be closer to the ground than the MEI. The second modification was to 

assume no vegetation intake pathway for muskrat and heron because they are not known to 

consume vegetation. The gaseous effluent releases used in estimating dose are found in Table 

3.5-2 of the ER (STPNOC 2010a). The ER used doses at the site area boundary in estimating 

terrestrial species doses. STPNOC’s dose estimates to the surrogate species from the liquid 

and gaseous pathways are shown in Table 5-13. As discussed in Appendix G, the NRC staff 

obtained slightly higher results in confirmatory calculations. 

5.9.5.3 Impact of Estimated Non-Human Biota Doses 

Radiological doses to non-human biota are expressed in units of absorbed dose (mrad) 

because dose equivalent (mrem) only applies to human radiological doses. The biota dose 

estimates of the new units are conservative because they do not consider dilution or decay of 

liquid effluents during transit. Actual doses to the biota are likely to be less than estimated. 

The ICRP (ICRP 1977; ICRP 1991, ICRP 2007) states that if humans are adequately protected, 

other living things are also likely to be sufficiently protected. The International Atomic Energy 

Agency (IAEA) (IAEA 1992) and the NCRP (NCRP 1991) reported that a chronic dose rate of no 

greater than 1000 mrad/d to the MEI in a population of aquatic organisms would ensure 

protection of the population. IAEA (1992) also concluded that chronic dose rates of 100 mrad/d 
 Operational Impacts at the Proposed Site 

February 2011 5-91 NUREG-1937 

or less do not appear to cause observable changes in terrestrial animal populations. Table 5-14 

compares STPNOC’s estimated total body dose to the biota from the proposed Units 3 and 4 to 

the IAEA chronic dose rate values for aquatic and terrestrial biota. Even considering the slightly 

higher doses to biota calculated by the NRC staff (see Appendix G) from the gaseous effluent 

pathway, the dose rates would be far less than the NCRP and IAEA guidelines. 

Table 5-14. Comparison of Biota Doses from the Proposed Units 3 and 4 at the STP Site to 

Relevant Guidelines for Biota Protection 

Biota 

STPNOC 

Estimate of 

Dose to Biota 

(mrad/d) 

IAEA/NCRP Guidelines 

for Protection of Biota 

Populations (mrad/d) (a)

Fish 6.8 × 10-3 1000 

Invertebrate 1.5 × 10-2 1000 

Algae 1.5 × 10-3 1000 

Muskrat 3.0 × 10-2

 100 

Raccoon 3.1 × 10-2

 100 

Heron 3.0 × 10-2

 100 

Duck 3.6 × 10-2 100 

(a) Published guidelines reported in mGy/d (1 mGy equals 100 mrad). 

Based on the information provided by STPNOC and NRC's review, the NRC staff concludes that 

the radiological impact on biota from the routine operation of the proposed Units 3 and 4 at the 

STP site would be SMALL, and additional mitigation would not be warranted. 

5.9.6 Radiological Monitoring 

A radiological environmental monitoring program (REMP) has been in place for the STP site 

since 1986, when preoperational sample collection activities began before the construction and 

operation of existing STP Units 1 and 2 (STPNOC 2010a). The REMP includes monitoring of 

the airborne exposure pathway, direct exposure pathway, water exposure pathway, aquatic 

exposure pathway from the Colorado River, and the ingestion exposure pathway in a 5-mi 

radius of the station, with indicator locations near the plant perimeter and control locations at 

distances greater than 10 mi. Milk is not currently sampled because there is no known 

production within 5 mi of the site. An annual land use census is conducted for the area 

surrounding the site to verify the accuracy of assumptions used in the analyses, including the 

occurrence of milk production. The preoperational REMP sampled various media in the 

environment to determine a baseline from which to observe the magnitude and fluctuation of 

radioactivity in the environment once the unit began operation. The pre-operational program 

included collection and analysis of samples of air particulates, precipitation, crops, soil, well 

water, surface water, fish, and silt as well as measurement of ambient gamma radiation. After 

operation of STP Unit 1 began in 1988, the monitoring program continued to assess the 
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NUREG-1937 5-92 February 2011 

radiological impacts on workers, the public, and the environment. Radiological releases and the 

results of the REMP are summarized in two annual reports: the Annual Radiological 

Environmental Operating Report (e.g., STPNOC 2010e) and Radioactive Effluent Release 

Report (e.g., STPNOC 2010f). No additional monitoring program has yet been established for 

the two new units. To the greatest extent practical, the REMP for the COL program would use 

the procedures and sampling locations used by the existing STP site. The NRC staff reviewed 

the documentation for the existing REMP, the Offsite Dose Calculation Manual, and recent 

monitoring reports from STPNOC, and determined that the current operational monitoring 

program is adequate to establish the radiological baseline for comparison with the expected 

impacts on the environment related to the construction and operation of the proposed new units 

at the STP site. 

STPNOC now performs additional groundwater sampling around the STP site in support of the 

NEI Ground Water Protection Initiative (see Section 5.2.2.2). These results are summarized in 

the 2009 Annual Radiological Environmental Operating Report (STPNOC 2010e). Drinking 

water in the area is obtained from deep aquifer wells, which are monitored quarterly, and no 

tritium has been detected in this water. However, tritium is released to the MCR. Monitoring 

shows that levels of tritium in the shallow aquifer around the MCR originating from the liquids 

discharged to the MCR are below the EPA drinking water standards (DWS) (40 CFR Part 141). 

Historical monitoring data for the MCR water show a peak tritium concentration of 

17,410 picocuries per liter (pCi/L) in 1996 and values less than 14,000 pCi/L since 

(STPNOC 2010a). A relief well monitored since 1995 showed a peak tritium concentration 

value of 7672 pCi/L in 1998 and values less than 7000 pCi/L since then. Tritium activity in an 

onsite well completed in the Shallow Aquifer shows a peak in the year 2000 of less than 

8000 pCi/L, and lower values before and after (STPNOC 2010e). During 2005, STPNOC 

collected six samples from an onsite well; all exceeded the tritium detection limit (260 pCi/L). A 

tritium concentration of 1200 pCi/L was observed (STPNOC 2010a). During 2006, a special 

study of 16 Shallow Aquifer, STPNOC-controlled wells surrounding the MCR and located 

outside the Protected Area of existing STP Units 1 and 2 was conducted (STPNOC 2010a, 

2007). Review of the Annual Radiological Environmental Operating Report revealed tritium 

concentrations ranging from less than 260 pCi/L to a little over 5000 pCi/L (STPNOC 2007).. 

Review of the Annual Radiological Environmental Operating Report revealed a highest 

observed mean tritium concentration of 1600 pCi/L (STPNOC 2007). A higher result was 

obtained in 2007 when the highest recorded mean was 5300 pCi/L (STPNOC 2008f). 

The relief well system, (i.e., 770 wells that surround the MCR), is designed in part to intercept 

the majority of the seepage from the MCR into the Upper Shallow Aquifer. STPNOC (2010a) 

has estimated that total seepage from the MCR is 3530 gpm (5700 ac-ft/yr), and that 

approximately 68 percent of this or 2390 gpm (3850 ac-ft/yr) is intercepted by the relief wells 

and discharged under the TDPES permit (TCEQ 2005). Following publication of the draft EIS, 
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February 2011 5-93 NUREG-1937 

recent simulation of the Shallow Aquifer underlying the STP site has indicated that the relief 

wells and sand drains intercept approximately 50 percent of the total seepage from the MCR 

(STPNOC 2010b). During operation of existing STP Units 1 and 2 the annual release of tritium 

into the MCR has varied from less than 500 Ci/yr to approximately 3700 Ci/yr with the release in 

2006 between 2000 and 2500 Ci, and in 2007 less than 1500 Ci (STPNOC 2007; 2008f). 

Reported concentrations of tritium in the MCR are below the EPA DWS (i.e., 20,000 pCi/L) 

(65 FR 76707) and those in groundwater are well below the DWS. Reported concentrations are 

well below the NRC reporting level of 30,000 pCi/kg. Of the radionuclides measured in the 

laboratory, only tritium was detected above its detection limits in the shallow aquifer test wells 

and piezometers (STPNOC 2007, 2008f). 

5.10 Nonradioactive Waste Impacts 

This section describes the potential impacts to the environment that could result from the 

generation, handling, and disposal of nonradioactive waste and mixed waste during the 

operation of proposed Units 3 and 4 at the STP site. 

Section 3.4.4 describes the nonradioactive waste systems for STP Units 3 and 4. Types of 

nonradioactive waste that would be generated, handled, and disposed of during operational 

activities at proposed Units 3 and 4 include solid wastes, liquid effluents, and air emissions. 

Solid wastes include municipal waste, dredge spoils, sewage treatment sludge, and industrial 

wastes. Liquid waste includes TPDES-permitted discharges such as effluents containing 

chemicals or biocides, wastewater effluents, site stormwater runoff, and other liquid wastes 

such as used oils, paints, and solvents that require offsite disposal. Air emissions would 

primarily be generated by vehicles, diesel generators, and combustion generators. In addition, 

small quantities of hazardous waste, and mixed waste, which is waste that has both hazardous 

and radioactive characteristics, may be generated during plant operations (STPNOC 2010a). 

The assessment of potential impacts resulting from these types of wastes is presented in the 

following sections. 

5.10.1 Impacts to Land 

Operation of proposed Units 3 and 4 would generate solid and liquid wastes similar to those 

already generated by current operation of STP Units 1 and 2. Total volume of solid and liquid 

wastes would increase, however no new solid or liquid waste types are expected to result from 

the operation of the new Units 3 and 4. Process wastes such as waste oils, solvents, paints, 

and hydraulic fluids are transported offsite for either fuel blending and thermal recovery, or 

recycling. STPNOC has indicated it would continue to use recycling and waste minimization 

practices to reduce offsite disposal of non-sanitary solid and liquid waste. Current recycling and 

waste minimization practices at the STP site reflect a recycling rate of 70 percent for all 

nonradioactive solid waste, including paper, scrap metal, used oil, antifreeze, and non-lead 
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NUREG-1937 5-94 February 2011 

batteries. Solid waste that cannot be recycled is transported to an offsite landfill 

(STPNOC 2010a). 

Debris from trash racks on the RMPF is routinely collected and disposed of according to TECQ 

regulations at an offsite landfill. Spoils from maintenance dredging of the barge slip and in front 

of the RMPF would be stockpiled and/or disposed at an approved onsite or offsite location 

according to new or revised Corps Section 404 and Section 10 permits for the STP site. Both of 

these wastes generated during the operation of Units 3 and 4 would follow current disposal 

management plans for existing STP Units 1 and 2 (STPNOC 2010a). 

Two onsite wastewater treatment facilities collect and treat sanitary waste. Currently, activated 

sludge from these facilities is dewatered onsite and shipped offsite as Texas Class 2 industrial 

waste to a permitted landfill operated by Republic Waste Services in Fresno, Texas. The 

increased sludge that would be generated by the operation of two additional units would be 

treated in a similar manner to the sludge from operation of Units 1 and 2 (STPNOC 2010a, d). 

Based on the effective practices for recycling and minimizing waste already in place for STP 

Units 1 and 2, and the plans to manage solid and liquid wastes in a similar manner in 

accordance with all applicable Federal, State, and local requirements and standards, the review 

team expects that impacts to land from nonradioactive wastes generated during the operation of 

proposed Units 3 and 4 would be minimal, and no further mitigation would be warranted. 

5.10.2 Impacts to Water 

Effluents containing chemicals or biocides would be discharged from proposed Units 3 and 4 to 

the MCR. Effluents include discharges from the wastewater treatment system, the circulating 

water treatment system, nonradioactive floor drains, site stormwater runoff, and cooling system 

discharge. As stated above, two wastewater treatment facilities currently receive, treat, and 

discharge treated wastewater to the MCR through TCEQ permitted outfalls. The existing 

wastewater treatment facilities would be replaced or upgraded to serve all four units. To 

properly manage stormwater flow, STPNOC would update its existing SWPPP to reflect the 

increase in impervious surfaces and changes in onsite drainage patterns (STPNOC 2010a, d). 

Section 5.2.3 discusses impacts to surface- and groundwater quality from operation of Units 3 

and 4. Nonradioactive liquid effluents that would be discharged to the MCR and subsequently, 

to the Colorado River, would be regulated by TCEQ and subject to limitations contained in the 

site’s TPDES permit (TCEQ 2005). STPNOC anticipates that it would be necessary to revise or 

apply for a new TPDES permit to accommodate increased discharges to the MCR and the 

Colorado River resulting from operation of STP Units 3 and 4 (STPNOC 2010a); in either case, 

discharges would be subject to limitations contained in STPNOC’s TPDES permit. 

Based on the regulated practices for managing liquid discharges containing chemicals or 

biocide, and other wastewater, and the plans for managing stormwater, the review team expects 
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February 2011 5-95 NUREG-1937 

that impacts to water from nonradioactive effluents during the operation of Units 3 and 4 would 

be minimal and no further mitigation would be warranted. 

5.10.3 Impacts to Air 

Operation of proposed Units 3 and 4 would result in gaseous emissions from the intermittent 

operation of emergency diesel generators and combustion generators. In addition, increased 

vehicular traffic associated with personnel necessary to operate Units 3 and 4 would increase 

vehicle emissions in the area. Impacts to air quality are discussed in detail in Section 5.7. 

Increases in air emissions from operation of Units 3 and 4 would be in accordance with permits 

issued by TCEQ that would ensure compliance with the Clean Air Act (STPNOC 2010a). 

Based on the regulated practices for managing air emissions from stationary sources, the 

review team expects that impacts to air from nonradioactive emissions during the operation of 

proposed Units 3 and 4 would be minimal and no further mitigation would be warranted. 

5.10.4 Mixed Waste Impacts 

Mixed waste contains both low-level radioactive waste and hazardous waste. The generation, 

storage, treatment, or disposal of mixed waste is regulated by Atomic Energy Act of 1954, the 

Solid Waste Disposal Act of 1965, as amended by the Resource, Conservation, and Recovery 

Act (RCRA) in 1976, and the Hazardous and Solid Waste Amendments (which amended RCRA 

in 1984). Each reactor at the STP site can be expected to produce on the order of 0.5 m3

 per 

year of mixed waste. However, no mixed waste has been generated at STP Units 1 and 2 in 

the past five years, in part, due to waste minimization practices (STPNOC 2010a). Mixed waste 

can be reduced through decay, stabilization, neutralization, or filtration. STPNOC stated that 

mixed waste that cannot be treated onsite would be temporarily stored until shipment for offsite 

disposal at an approved facility; existing STPNOC procedures for storage of mixed wastes 

would be used to limit occupational exposure or accidental spill (STPNOC 2010a). 

Based on the effective practices for minimizing waste already in place for STP Units 1 and 2, 

and the plans to manage mixed wastes in a similar manner in accordance with all applicable 

Federal, State, and local requirements and standards, the review team expects that impacts 

from the generation of mixed waste at STP Units 3 and 4 would be minimal, and no further 

mitigation would be warranted. 

5.10.5 Summary of Waste Impacts 

Solid, liquid, gaseous, and mixed wastes generated during operation of proposed Units 3 and 4 

would be handled according to county, State, and Federal regulations. County and State 

permits and regulations for handling and disposal of solid waste, and Corps permits for disposal 

of dredged spoils, would be obtained and implemented. A revised SWPPP for surface water 
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NUREG-1937 5-96 February 2011 

runoff and TCEQ permits for permitted releases of cooling and auxiliary system effluents would 

ensure compliance with the Federal Water Pollution Control Act (Clean Water Act) and TCEQ 

water quality standards. Wastewater discharge would be compliant with TPDES limitations. Air 

emissions from Units 3 and 4 operations would be compliant with air quality standards as 

permitted by TCEQ. Mixed waste generation, storage, and disposal impacts during operation of 

proposed Units 3 and 4 would be compliant with requirements and standards. 

Based on the information provided by STPNOC, the effective practices for recycling, minimizing, 

managing, and disposing of wastes already in use at the STP site, the review team’s 

expectation that regulatory approvals would be obtained to regulate the additional waste that 

would be generated from proposed Units 3 and 4, and the review team’s independent 

evaluation, the review team concludes that the potential impacts from nonradioactive waste 

resulting from the operation of the proposed two additional units at the STP site would be 

SMALL, and mitigation would not be warranted. 

Cumulative impacts to water and air from nonradioactive emissions and effluents are discussed 

in Sections 7.2.2.1 and 7.6 respectively. For the purposes of Chapter 9, the review team 

expects that there would be no substantive differences between the impacts of nonradioactive 

waste for the STP site and the three alternative sites and no substantive cumulative impacts 

that warrant further discussion beyond those discussed for the alternative sites in Section 9.3. 

5.11 Environmental Impacts of Postulated Accidents 

The NRC staff considered the radiological consequences on the environment of potential 

accidents at the proposed new units at the STP site. Consequence estimates are based on the 

ABWR certified design as set forth in 10 CFR Part 52, Appendix A. The term “accident,” as 

used in this section, refers to any off-normal event not addressed in Section 5.9 that results in 

release of radioactive materials into the environment. The focus of this review is on events that 

could lead to releases substantially in excess of permissible limits for normal operations. 

Normal release limits are specified in 10 CFR Part 20, Appendix B, Table 2. 

Numerous features combine to reduce the risk associated with accidents at nuclear power 

plants. Safety features in the design, construction, and operation of the plants, which comprise 

the first line of defense, are intended to prevent the release of radioactive materials from the 

plant. The design objectives and the measures for keeping levels of radioactive materials in 

effluents to unrestricted areas ALARA are specified in 10 CFR Part 50, Appendix I. There are 

additional measures that are designed to mitigate the consequences of failures in the first line of 

defense. These measures include the NRC’s reactor siting criteria in 10 CFR Part 100, which 

require the site to have certain characteristics that reduce the risk to the public and the potential 

impacts of an accident, and emergency preparedness plans and protective action measures for 

the site and environs, as set forth in 10 CFR 50.47, 10 CFR Part 50, Appendix E, and NUREG-
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February 2011 5-97 NUREG-1937 

0654/FEMA-REP-1, Criteria for Preparation and Evaluation of Radiological Emergency 

Response Plans and Preparedness in Support of Nuclear Power Plants (NRC 1980). All of 

these safety features, measures, and plans make up the defense-in-depth philosophy to protect 

the health and safety of the public and the environment. 

This section discusses (1) the types of radioactive materials that may be released, (2) the 

potential paths for their release to the environment, (3) the relationship between radiation dose 

and health effects, and (4) the environmental impacts of reactor accidents, both design-basis 

accidents (DBAs) and severe accidents. The environmental impacts of accidents during 

transportation of spent fuel are discussed in Chapter 6. 

The potential for dispersion of radioactive materials in the environment depends on the 

mechanical forces that physically transport the materials and on the physical and chemical 

forms of the material. Radioactive material exists in a variety of physical and chemical forms. 

The majority of the material in the fuel is in the form of nonvolatile solids. However, after 

operation, a significant fraction of the material is in the form of volatile solids or gases. The 

gaseous radioactive materials include the chemically inert noble gases (e.g., krypton and 

xenon), which have a high potential for release. Radioactive forms of iodine, which are created 

in substantial quantities in the fuel by fission, are volatile. Other radioactive materials formed 

during the operation of a nuclear power plant have lower volatilities and, therefore, have lower 

tendencies to escape from the fuel than the noble gases and isotopes of iodine. 

Radiation exposure to individuals is determined by their proximity to radioactive material, the 

duration of their exposure, and the extent to which they are shielded from the radiation. 

Pathways that lead to radiation exposure include (1) external radiation from radioactive material 

in the air, on the ground, and in the water; (2) inhalation of radioactive material; and 

(3) ingestion of food or water containing material initially deposited on the ground and in water. 

Radiation protection experts assume that any amount of radiation may pose some risk of 

causing cancer or a severe hereditary effect and that the risk is higher for higher radiation 

exposures. Therefore, a linear, no-threshold dose response relationship is used to describe the 

relationship between radiation dose and detriments such as cancer induction. A recent report 

by the National Research Council (2006), the BEIR VII report, uses the linear, no-threshold 

dose response model as a basis for estimating the risks from low doses. This approach is 

accepted by the NRC as a conservative method for estimating health risks from radiation 

exposure, recognizing that the model may overestimate those risks. 

Physiological effects are clinically detectable if individuals receive radiation exposure resulting in 

a dose greater than about 25 rem over a short period (hours) (IAEA 2001). Untreated doses of 

about 250 to 500 rem received over a relatively short period (hours to a few days) can be 

expected to cause some fatalities.
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NUREG-1937 5-98 February 2011 

5.11.1 Design Basis Accidents 

STPNOC evaluated the potential consequences of postulated accidents to demonstrate that an 

ABWR could be constructed and operated at the STP site without undue risk to the health and 

safety of the public (STPNOC 2010a). These evaluations used a set of DBAs that are 

representative for the reactor design being considered for the STP site and site-specific 

meteorological data. The set of accidents covers events that range from relatively high 

probability of occurrence with relatively low consequences to relatively low probability with high 

consequences. 

The DBA review focuses on the certified ABWR at the STP site. The bases for analyses of 

postulated accidents for this design are well established because they have been considered as 

part of the NRC’s reactor design certification process (10 CFR Part 52, Subpart B). Potential 

consequences of DBAs are evaluated following procedures outlined in regulatory guides and 

standard review plans. The potential consequences of accidental releases depend on the 

specific radionuclides released, the amount of each radionuclide released, and the 

meteorological conditions. The source terms for the ABWR for evaluating potential accidents 

are based on guidance in Regulatory Guide 1.3, “Assumptions Used for Evaluating the Potential 

Radiological Consequences of a Loss of Coolant Accident for Boiling Water Reactors” 

(NRC 1974). 

For environmental reviews, consequences are evaluated assuming realistic meteorological 

conditions. Meteorological conditions are represented in these consequence analyses by an 

atmospheric dispersion factor, also referred to as relative concentration (χ/Q), which has units of 

s/m3

. Small χ/Q values are associated with greater dilution capability. Acceptable methods of 

calculating χ/Q for DBAs from meteorological data are set forth in Regulatory Guide 1.145, 

“Atmospheric Dispersion Models for Potential Accident Consequence Assessments at Nuclear 

Power Plants” (NRC 1983). 

Table 5-15 repeats χ/Q values pertinent to the environmental review of DBAs for the STP site 

that were presented earlier in Table 2-39. The first column lists the time periods and boundaries 

for which χ/Q and dose estimates are needed. For the EAB, the postulated DBA dose and its 

atmospheric dispersion factor are calculated for a short-term (i.e., 2 hours), and for the Low 

Population Zone (LPZ), they are calculated for the course of the accident, i.e., 30 days 

(720 hours) composed of four time periods. The NRC staff reviewed the χ/Q values presented 

by STPNOC and concluded that they were overly conservative. Therefore, the NRC staff 

calculated 50th percentile χ/Q values using the STP site meteorological information discussed 

in ER Sections 2.7.4 and 6.4. The staff used these χ/Qs to estimate the environmental 

consequences of DBAs. The second column in Table 5-15 lists the χ/Q values calculated by 

the NRC staff assuming ground-level releases located on a line enclosing all potential release 

points. 
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February 2011 5-99 NUREG-1937 

Table 5-15. Atmospheric Dispersion Factors for STP Site DBA Calculations

Time Period and Boundary χ/Q (s/m3

) 

0 to 2 hr, Exclusion Area Boundary 3.64 x 10-5

0 to 8 hr, Low Population Zone 2.53 x 10-6

8 to 24 hr, Low Population Zone 2.23 x 10-6

1 to 4 d, Low Population Zone 1.70 x 10-6

4 to 30 d, Low Population Zone 1.15 x 10-6

Table 5-16 lists the set of DBAs considered by STPNOC and presents the NRC staff’s 

estimates of the potential environmental consequences of each accident in terms of thyroid 

dose from inhalation and the whole body dose from external exposure. The staff reviewed the 

STPNOC selection of DBAs by comparing the accidents listed in the application with the DBAs 

considered in the ABWR design control document (GE1994; NRC 1994, 1997a). The DBAs in 

the ER are an appropriate subset of those considered in the design certification. The doses in 

Table 5-16 were calculated by the NRC staff from the DBA doses in the design control 

document using the ratio of the staff’s site-specific atmospheric dispersion factors in Table 5-16 

to the atmospheric dispersion factors assumed for the design certification. 

Table 5-16. Design Basis Accident Doses for an ABWR 

Accident 

SRP 

Section(b)

Doses in rem(a)

EAB LPZ Review Criterion

Whole 

Body Thyroid 

Whole 

Body Thyroid 

Whole 

Body Thyroid 

Main Steamline Break 15.6.4 

 Pre-existing Iodine Spike 0.035 1.4 0.0024 0.094 25(c) 300(c)

 Accident-Initiated Spike 0.0017 0.069 0.00011 0.0048 2.5(d) 30(d)

Loss-of-Coolant Accident 15.6.5 0.11 5.1 0.23 22 25(c)

 300(c)

Failure of Small Line Carrying 

Primary Coolant Outside 

Containment 

15.6.2 0.0025 0.013 0.00017 0.0089 2.5(d) 30(d)

Fuel Handling 15.7.4 0.032 2.0 0.0022 0.14 6(d) 75(d)

Cleanup Water Line Break 

Outside Containment 

 0.00035 0.037 0.000031 0.0033 25(c)

 300(c)

(a) To convert rem to Sv divide by 100 

(b) NUREG-0800 (NRC 2007) 

(c) 10 CFR 100.11 and 10 CFR 50.34(a)(1) criterion 

(d) Standard Review Plan criterion 
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NUREG-1937 5-100 February 2011 

There are no environmental criteria related to the potential consequences of DBAs. 

Consequently, the review criteria used in the NRC staff’s safety review of DBA doses are 

included in Table 5-16 to illustrate the magnitude of the calculated environmental 

consequences (whole body and thyroid doses). In all cases, the calculated environmental 

consequences (doses) are considerably smaller than the doses used as safety review criteria.

Summary of DBA Impacts. The NRC staff reviewed the STPNOC DBA analysis, which is based 

on analyses performed for the design certification of the ABWR design with adjustment for STP 

site-specific characteristics. The results of the STPNOC analyses presented in its ER indicate 

that the environmental risks associated with DBAs, if an ABWR was to be located at the STP 

site, would be small. The NRC staff performed an independent assessment of the 

environmental consequences of DBAs at the STP site and concludes that the environmental 

consequences of DBAs would be SMALL. 

5.11.2 Severe Accidents 

In its ER (STPNOC 2010a), STPNOC considers the potential consequences of severe accidents 

for an ABWR at the STP site. Three pathways are considered: (1) the atmospheric pathway, in 

which radioactive material is released to the air; (2) the surface-water pathway, in which 

airborne radioactive material falls out on open bodies of water; and (3) the groundwater 

pathway, in which groundwater is contaminated by a basemat melt-through with subsequent 

contamination of surface water by the groundwater. 

The STPNOC evaluation of the potential environmental consequences for the atmospheric 

pathway incorporates the results of the MELCOR Accident Consequence Code System 

(MACCS2) computer code (Chanin et al. 1990; Jow et al. 1990) run using ABWR reactor source 

term information and site-specific meteorological, population, and land-use data. The NRC staff 

has reviewed STPNOC input and output files, has run confirmatory calculations, and finds the 

STPNOC results reasonable. 

The MACCS2 computer code was developed to evaluate the potential offsite consequences of 

severe accidents for the sites covered by NUREG-1150, Severe Accident Risks: An 

Assessment for Five U.S. Nuclear Power Plants: Final Summary Report (NRC 1990). The 

MACCS2 code evaluates the consequences of atmospheric releases of radioactive material 

following a severe accident. The pathways modeled include exposure to the passing plume, 

exposure to radioactive material deposited on the ground and skin, inhalation of material in the 

passing plume and resuspended from the ground, and ingestion of radioactively contaminated 

food and surface water. 

Three types of severe accident consequences were assessed in the MACCS2 analysis: 

(1) human health, (2) economic costs, and (3) land area affected by contamination. Human 

health effects are expressed in terms of the number of cancers that might be expected if a 
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February 2011 5-101 NUREG-1937 

severe accident were to occur. These effects are directly related to the cumulative radiation 

dose received by the general population. MACCS2 estimates both early cancer fatalities and 

latent fatalities. Early fatalities are related to high doses or dose rates and can be expected to 

occur within a year of exposure (Jow et al. 1990). 

Latent fatalities are related to exposure of a large number of people to low doses and dose rates 

and can be expected to occur after a latent period of several (2 to 15) years. Population healthrisk estimates are based on the population distribution within a 50-mi radius of the site. 

Economic costs of a severe accident include the costs associated with short-term relocation of 

people; decontamination of property and equipment; interdiction of food supplies, land, and 

equipment use; and condemnation of property. The affected land area is a measure of the areal 

extent of the residual radioactive contamination following a severe accident. Farmland 

decontamination is an estimate of the area that has an average whole body dose rate for the 

4-year period following the release that would be greater than 0.5 rem/yr if not reduced by 

decontamination and that would have a calculated dose rate following decontamination of less 

than 0.5 rem/yr. Decontaminated land is not necessarily suitable for farming.

Risk is the product of the frequency and the consequences of an accident. For example, the 

probability of a severe accident without loss of containment for an ABWR reactor at the STP site 

is estimated to be 1.34 ×10-7 per reactor year (Ryr-1), and the cumulative population dose 

associated with a severe accident without loss of containment at the STP site is calculated to be 

19,600 person-rem. The population dose risk for this class of accidents is the product of 

1.34 ×10-7 Ryr-1 and 19,600 person-rem, or 2.63 ×10-3 person-rem Ryr-1. 

The following sections discuss the estimated risks associated with each pathway. The risks 

presented in the tables that follow are risks per year of reactor operation. STPNOC has 

submitted an application to construct and operate two ABWRs at the STP site. The 

consequences of a severe accident would be the same regardless of whether one or two 

reactors were built at the site. However, if two reactors were built, the risks would apply to each 

reactor, and the total risk for new reactors at the site would be twice the risk for a single reactor. 

5.11.2.1 Air Pathway 

The MACCS2 code directly estimates consequences associated with releases to the air 

pathway. STPNOC used the MACCS2 code to estimate consequences to the population in 

2060 based on meteorological data for 1997, 1999 and 2000. The results of the MACCS2 

calculations presented in the following tables are the averages of the estimates for the 3 years. 

The core damage frequencies (CDFs) given in these tables are for internally initiated accident 

sequences while the plant is at power. Internally initiated accident sequences include 

sequences that are initiated by human error, equipment failures, loss of offsite power, etc. 

Estimates of the core damage frequencies for externally initiated events and during shutdown 

are discussed later. 
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NUREG-1937 5-102 February 2011 

Table 5-17 presents the probability-weighted consequences, i.e., risks, of severe accidents for 

an ABWR reactor located on the STP site that contribute 1 percent or more to at least one risk 

category. Risks are small for all risk categories considered. For perspective, Table 5-18 and 

Table 5-19 compare the health risks from severe accidents for an ABWR reactor at the STP site 

with the risks for current-generation reactors at various sites and with an ABWR reactor at the 

North Anna, Clinton, and Grand Gulf Early Site Permit (ESP) sites. 

In Table 5-18, the health risks estimated for an ABWR at the STP site are compared to healthrisk estimates for the five reactors considered in NUREG-1150 (NRC 1990). Although risks 

associated with both internally and externally initiated events were considered for the Peach 

Bottom and Surry reactors in NUREG-1150, only risks associated with internally initiated events 

are presented in Table 5-18. The health risks shown for ABWR at the STP site are significantly 

lower than the risks associated with current-generation reactors presented in NUREG-1150. 

Table 5-18 also compares health risks of an ABWR at the STP site with health risks for an 

ABWR at three ESP sites (NRC 2006a, b, c). 

The last two columns of Table 5-18 provide average individual fatality risk estimates. To put 

these estimates into context for the environmental analysis, the staff compares these estimates 

to the safety goals. The Commission has set safety goals for average individual early fatality 

and latent cancer fatality risks from reactor accidents in the Safety Goal Policy Statement 

(51 FR 30028). These goals are presented here solely to provide a point of reference for the 

environmental analysis and do not serve the purpose of a safety analysis. The Policy 

Statement expressed the Commission’s policy regarding the acceptance level of radiological 

risk from nuclear power plant operation as follows: 

• Individual members of the public should be provided a level of protection from the 

consequences of nuclear power plant operation such that individuals bear no significant 

additional risk to life and health. 

• Societal risks to life and health from nuclear power plant operation should be comparable to 

or less than the risks of generating electricity by viable competing technologies and should 

not be a significant addition to other societal risks. 
 Operational Impacts at the Proposed Site

February 2011 5-103 NUREG-1937 Table 5-17. Mean Environmental Risks from ABWR Reactor Severe Accidents at the STP Site Release Category Description (Accident Class) Core Damage Frequency(a) (Ryr-1) Environmental Risk Population Dose(b) (person-rem Ryr-1) Fatalities (Ry-1) Cost(e) ($ Ryr-1) Land Requiring Decontamination(f) (ac Ryr-1) Population Dose from Water Ingestion(b) (person-rem Ryr-1) Early(c) Latent(d) 0 No loss of containment 1.34 x 10-7 2.63 × 10-3 0.0 1.57 × 10-6 0.01 5.79 × 10-7 4.22 × 10-6 1 Transients followed by failure of high- pressure coolant makeup water and failure to depressurize in timely fashion 2.08 x 10-8 2.29 × 10-4 0.0 1.37 × 10-7 0.00 9.82 × 10-9 3.71 × 10-7 3 Station blackout with Reactor Core Isolation Cooling (RCIC) available for about 8 hr 1.00 x 10-10 3.57 × 10-5 0.0 2.14 × 10-8 0.00 1.14 × 10-6 2.28 × 10-7 6 Transient, loss-of-coolant accident (LOCA), and anticipated transient without scram (ATWS) events with successful coolant makeup water, but potential prior failure of containment 1.00 x 10-10 9.01 × 10-5 0.0 5.41 × 10-8 0.15 1.27 × 10-5 1.05 × 10-5 7 Small/medium LOCA followed by failure of high-pressure coolant makeup water and failure to depressurize 3.91 x 10-10 3.84 × 10-4 6.63 × 10-16 2.31 × 10-7 0.58 5.80 × 10-5 5.29 × 10-5 8 LOCA followed by failure of high-pressure coolant makeup water 4.05 x 10-10 5.74 × 10-4 2.12 × 10-13 3.46 × 10-7 0.96 6.75 × 10-5 1.46 × 10-4 9 ATWS followed by boron injection failure and successful high-pressure coolant makeup water 1.70 x 10-10 2.64 × 10-4 2.16 × 10-13 1.60 × 10-7 0.52 2.48 × 10-5 8.38 × 10-5 Total 1.56 x 10-7 4.24 × 10-3 4.29 × 10-13 2.54 × 10-6 2.23 1.66 × 10-4 2.98 × 10-4 (a) Source: GE 1997 (b) To convert to person-Sv, divide by 100. (c) Early fatalities are fatalities related to high doses or dose rates that generally can be expected to occur within a year of the exposure (Jow et al. 1990). (d) Latent fatalities are fatalities related to low doses or dose rates that could occur after a latent period of several (2 to 15) years. (e) Cost risk includes costs associated with short-term relocation of people, decontamination, interdiction, and condemnation. It does not include costs associated with health effects (Jow et al. 1990). (f) Land risk is farmland requiring decontamination prior to resumption of agricultural usage. 
Operational Impacts at the STP Site

NUREG-1937 5-104 February 2011 Table 5-18. Comparison of Environmental Risks for an ABWR Reactor at the STP Site with Risks for Current- Generation Reactors at Five Sites Evaluated in NUREG-1150(a) Core Damage Frequency (Ryr-1) 50-mi Population Dose Risk (person-rem Ryr-1)(b) Fatalities Ryr-1 Average Individual Fatality Risk Ryr-1 Early Latent Early Latent Cancer Grand Gulf(c) 4.0 x 10-6 5 x 10+1 8 x 10-9 9 x 10-4 3 x 10-11 3 x 10-10 Peach Bottom(c) 4.5 x 10-6 7 x 10+2 2 x 10-8 5 x 10-3 5 x 10-11 4 x 10-10 Sequoyah(c) 5.7 x 10-5 1 x 10+3 3 x 10-5 1 x 10-2 1 x 10-8 1 x 10-8 Surry(c) 4.0 x 10-5 5 x 10+2 2 x 10-6 5 x 10-3 2 x 10-8 2 x 10-9 Zion(c) 3.4 x 10-4 5 x 10+3 4 x 10-5 2 x 10-2 9 x 10-9 1 x 10-8 ABWR(d) Reactor at the STP site 1.6 x 10-7 4.2 x 10-3 4.3 x 10-13 2.5 x 10-6 5.8 x 10-14 3.1 x 10-12 ABWR(e) Reactor at North Anna 1.6 x 10-7 5.9 x 10-3 2.4 x 10-11 2.7 x 10-6 4.6 x 10-14 4.4 x 10-12 ABWR(f) Reactor at Clinton 1.6 x 10-7 2.4 x 10-3 7.9 x 10-10 1.0 x 10-6 3.8 x 10-14 3.9 x 10-12 ABWR(g) Reactor at Grand Gulf 1.6 x 10-7 2.1 x 10-3 1 x 10-12 9 x 10-7 2 x 10-14 3 x 10-12 (a) NRC 1990 (b) To convert to person-Sv, divide by 100. (c) Risks were calculated using the MACCS code and presented in NUREG-1150 (NRC 1990). (d) Calculated with MACCS2code using STP site-specific input. (e) NUREG-1811 (NRC 2006a) (f) NUREG-1815 (NRC 2006b) (g) NUREG-1817 (NRC 2006c) 
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February 2011 5-105 NUREG-1937 

Table 5-19. Comparison of Environmental Risks from Severe Accidents Initiated by Internal 

Events for an ABWR Reactor at the STP Site with Risks Initiated by Internal Events 

for Current Plants Undergoing Operating License Renewal Review and 

Environmental Risks of the ABWR Reactor at Other Sites 

Core 

Damage 

Frequency 

(Ryr-1)

80-km (50-mi) 

Population Dose 

Risk 

 (person-rem Ryr-1)

(a)

Current Reactor Maximum(b) 2.4 x 10-4 6.9 x 10+1

Current Reactor Mean(b) 2.7 x 10-5 1.6 x 10+1

Current Reactor Median(b) 1.6 x 10-5

 1.3 x 10+1

Current Reactor Minimum(b) 1.9 x 10-6

 3.4 x 10-1 

ABWR(c) Reactor at the STP Site 1.6 x 10-7 4.2 x 10-3

ABWR(d) Reactor at North Anna 1.6 x 10-7 5.9 x 10-3

ABWR(e) Reactor at Clinton 1.6 x 10-7 2.4 x 10-3

ABWR(f) Reactor at Grand Gulf 1.6 x 10-7

 2.1 x 10-3

(a) To convert to person-Sv, divide by 100. 

(b) Based on MACCS and MACCS2 calculations for 76 currently operating plants 

at 44 sites. 

(c) Calculated with MACCS2 code using STP site-specific input. 

(d) NUREG-1811 (NRC 2006a) 

(e) NUREG-1815 (NRC 2006b) 

(f) NUREG-1817 (NRC 2006c) 

The following quantitative health objectives are used in determining achievement of the safety 

goals: 

• The risk to an average individual in the vicinity of a nuclear power plant of prompt fatalities 

that might result from reactor accidents should not exceed one-tenth of 1 percent 

(0.1 percent) of the sum of prompt fatality risks resulting from other accidents to which 

members of the U.S. population are generally exposed. 

• The risk to the population in the area near a nuclear power plant of cancer fatalities that 

might result from nuclear power plant operation should not exceed one-tenth of 1 percent 

(0.1 percent) of the sum of cancer fatality risks resulting from all other causes. 

These quantitative health objectives are translated into two numerical objectives as follows: 

• The individual risk of a prompt fatality from all “other accidents to which members of the 

U.S. population are generally exposed,” is about 4.0 x 10-4 per year, including a 1.6 x 10-4

per year risk associated with transportation accidents (NSC 2006). One-tenth of 
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NUREG-1937 5-106 February 2011 

one percent of these figures implies that the individual risk of prompt fatality from a reactor 

accident should be less than 4 x 10-7 per Ryr-1. 

• “The sum of cancer fatality risks resulting from all other causes” for an individual is taken to 

be the cancer fatality rate in the United States which is about 1 in 500 or 2 x 10-3 per year 

(CDC 2007). One-tenth of one percent of this implies that the risk of cancer to the 

population in the area near a nuclear power plant because of its operation should be limited 

to 2 x 10-6 per Ryr-1. 

The MACCS2 computer code calculates average individual early and latent cancer fatality risks. 

The average individual early fatality risk is calculated using the population distribution within 

1 mi of the plant boundary. The average individual latent cancer fatality risk is calculated using 

the population distribution within 10 mi of the plant. For the plants considered in NUREG-1150 

(NRC 1990), these risks were well below the Commission’s safety goals. Risks calculated by 

STPNOC for the ABWR design at the STP site are lower than the risks associated with the 

current-generation reactors considered in NUREG-1150 and are well below the Commission’s 

safety goals. 

The NRC staff compared the CDF and population dose risk estimate for an ABWR at the STP 

site with statistics summarizing the results of contemporary severe accident analyses performed 

for 76 reactors at 44 sites. The results of these analyses are included in the final site-specific 

Supplements 1 through 37 to the GEIS for License Renewal, NUREG-1437 (NRC 1996a), and 

in the ERs included with license renewal applications for those plants for which supplements 

have not been published. All of the analyses were completed after publication of NUREG-1150 

(NRC 1990), and the analyses for 72 of the reactors used MACCS2, which was released in 

1997. Table 5-19 shows that the CDFs estimated for the ABWR are significantly lower than the 

core damage frequencies of current-generation reactors. Similarly, the population doses 

estimated for an ABWR at the STP site are well below the mean and median values for currentgeneration reactors undergoing license renewal. 

Finally, the population dose risk from a severe accident for an ABWR reactor at the STP site 

(4.1 x 10-3 person-rem/Ryr) may be compared to the dose risk for normal operation of a single 

ABWR reactor at the STP site (2.9 x 10-1 person-rem/Ryr) (see Section 5.9.3.2). The risk 

associated with a severe accident is two orders of magnitude lower than the risk associated with 

normal operations. Comparatively, the population dose risk associated with a severe accident 

is small. 

In developing a probabilistic risk assessment for a nuclear power plant, criteria are included to 

“screen out” information that is insignificant. Regulatory Guide 1.200 (NRC 2009a) discusses 

methods and criteria for determining if the contribution to risk from an initiating event is 

insignificant. For example, the risk potential of a severe accident at a co-located nuclear unit as 

an initiating event is insignificant compared to other initiating events because the event 
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February 2011 5-107 NUREG-1937 

frequency is very low. First, the frequency of a severe accident that results in an early large 

release of radioactive material to the environment is on the order of 1 x 10-6 per Ryr for currently 

operating nuclear power plants such as STP Units 1 and 2 (even lower for new reactors such as 

STP Units 3 and 4). Then that accident or the radioactive release from that accident has to 

create a problem that leads to the initiation of a severe accident at a co-located nuclear power 

plant. The radioactive release from the accident does not initiate an accident at the co-located 

reactor; however, it may set up conditions that could eventually lead to a severe accident at the 

co-located reactor. The wind direction must move the accident release toward the co-located 

units; the release must overwhelm the habitability systems such that operators on the colocated units have to be evacuated because of high dose rates; and the lack of continuous 

operator attention and action must eventually result in multiple system failures that lead to a loss 

of reactor cooling and containment failure. There is no detailed estimate of the combined 

probability of this sequence of events; however, the overall probability of a severe accident 

initiating a severe accident at a co-located reactor would be at least three orders of magnitude 

lower (10-9 per Ryr or less). This probability is insignificant compared to the overall probability of 

accident initiators, and consideration of this scenario as an initiating event is “screened out”. 

Based on this explanation, the NRC staff concludes the potential environmental impact of this 

accident scenario does not need to be evaluated because it is remote and speculative. 

Even though this accident scenario is remote and speculative, STPNOC made a bounding 

estimate of the population dose risk by postulating that a severe accident at one STP unit could 

cause a severe accident at the remaining units. STPNOC estimated the population dose risk for 

one ABWR at the STP site to be about 4 x 10-3 person-rem per Ryr (STPNOC 2010a), and 

further indicated that the large early release frequency for Units 1 and 2 is about 30 times higher 

than the large release frequency for Unit 3 and 4 (STPNOC 2009g). The resulting population 

risk for all four units would be less than one person-rem per Ryr. The NRC staff reviewed the 

applicant’s bounding analysis and concludes that the corresponding environmental risks would 

still be small based on comparisons with the environmental risks shown in Table 5-17. 

The ER does not address potential consequences from externally initiated events or events at 

low power and shutdown. The following paragraphs discuss risks from low power and 

shutdown events, tornado, internal floods and fires, external floods, and seismic events. 

For design certification, the ABWR vendor evaluated qualitatively features that minimize 

shutdown risk discussed in NUREG-1449, Shutdown and Low-Power Operation at Commercial 

Nuclear Power Plants in the United States (NRC 1993), which include internal floods and 

internal fire protection. The ABWR vendor also performed a detailed reliability study of the 

decay heat removal system which evaluated the conditional probability of core damage given 

loss of the operating residual heat removal system. Chapter 19 of the staff’s safety evaluation 

report (SER) (NRC 1994; 1997a) concluded that the ABWR vendor appropriately addressed 
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NUREG-1937 5-108 February 2011 

concerns in NUREG-1449 related to the capability to provide alternate core cooling in the case 

of a loss of the residual heat removal system. 

With respect to tornado-initiated events, the DCD (GE 1997) states that the total CDF is 

“extremely small” and is small compared to the internal events result. In the SER, the NRC staff 

noted that the ABWR is designed to withstand tornadoes with a 1 × 10-7 yr-1 frequency of 

occurrence and that the internal events evaluation includes loss-of-offsite power events, which 

are the most likely way in which a tornado would impact an ABWR. As a result, the NRC staff 

did not consider it necessary to assess tornado-initiated events probabilistically. 

With respect to internal floods and fires, the design certification analyses were based on 

conservative simplifying assumptions. In its SER, the staff estimated that the internal flooding 

events considered the most challenging and having the worst consequences had CDFs 

that were less than 1 ×10-8 yr-1, and that the CDF associated with internal fires was about 

1 × 10-6 yr-1. In addition, the staff noted “Because of conservatism in the analyses, the staff 

does not believe that the fire and internal flood core damage frequency estimates should be 

compared to those of internal events.” (NRC 1994) 

STPNOC’s Final Safety Analysis Report (FSAR) (STPNOC 2010c) reviews the DCD fire 

analysis and concludes that the fire analysis in the DCD bounds the risks at the STP site. The 

STPNOC FSAR repeats the DCD analyses of internal flooding of the turbine and control 

buildings. In each case, the FSAR concludes that the CDF is extremely small. The FSAR then 

presents an STP site-specific flooding analysis for the Reactor Service Water pump house and 

concludes that “This conservative bounding analysis shows that the CDF for internal flooding is 

very small...” (STPNOC 20010c) 

The applicant requested a design departure from the ABWR DCD site parameter 

(STP DEP T1-5.0-1) for the maximum flood level to 183 cm above grade (STPNOC 2010c). 

The plant design will be modified to account for the change in the level of the maximum flood at 

STP by including watertight doors for the external entrances to the control and reactor buildings; 

this will ensure that there is adequate protection for equipment in rooms containing critical 

equipment in the reactor and control buildings. STPNOC conducted an external event flooding 

analysis for the STP site that considered river flooding, tsunamis, dam failures, and storm 

surges from hurricanes; the one external initiating event related to flooding that was not 

excluded by the screening analysis was the breach of the MCR embankment. STPNOC also 

committed to develop procedures to ensure the watertight doors will be closed and controlled 

when necessary to prevent flooding in the reactor and control buildings, such as during a 

hurricane (STPNOC 2010c). 

Seismic events are considered in the DCD and SER using a “seismic margins analysis” 

approach that does not yield a CDF. The ABWR has a design basis safe shutdown earthquake 

of 0.3g; the STP site-specific value is lower than 0.3g. The result of the seismic margin analysis 
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February 2011 5-109 NUREG-1937 

is that there is a high confidence with low probability of failure that an ABWR would withstand a 

0.6g earthquake without core damage. 

5.11.2.2 Surface-Water Pathways 

Surface-water pathways are an extension of the air pathway. These pathways consider the 

effects of radioactive material deposited on open bodies of water. The surface-water pathways 

of interest include external radiation from submersion in water and activities near the water, and 

ingestion of water, fish, and other aquatic creatures. Of these pathways, the MACCS2 code 

evaluates only the ingestion of contaminated water. The risks associated with this surfacewater pathway calculated for the STP site are included in the last columns of Table 5-17. 

Environmental consequences of potential surface-water pathways related to immersion and 

ingestion (e.g., swimming and fishing) are not evaluated by MACCS2. STPNOC relied on 

generic analyses in NUREG-1437 (NRC 1996a) for the immersion pathway. NUREG-1437 

reiterates conclusions set forth in the Final Environmental Impact Statement Related to the 

Operation of Enrico Fermi Atomic Power Plant, Unit No. 2, NUREG-0769 (NRC 1981) that 

indicate that doses from shoreline activities and swimming are smaller than either water 

ingestion doses or aquatic food ingestion doses. In Table 5-17 the water ingestion dose risk is 

less than 10 percent of the air pathway dose risk. STPNOC also relied on the NUREG-1437 

analysis to estimate that the dose risk from uninterdicted ingestion of aquatic foods would be 

between 0.4 and 270 person rem per Ryr. 

NUREG-1437 (NRC 1996a) classifies the STP site as being a coastal or estuarine site. 

Table 5.16 in NUREG-1437 lists aquatic food harvest and uninterdicted aquatic food ingestion 

risks for several plants at coastal and estuarine sites. For this table, the population dose was 

related to aquatic food harvest assuming a linear relationship with a transfer factor (coefficient) 

of about 2.4 person-rem per kg of harvest. Using this value and the average Matagorda Bay 

aquatic harvest for the 2005 through 2007 seasons (PNNL 2009), the NRC staff estimates that 

the upper bound for the uninterdicted aquatic food pathway population dose risk is about 

0.1 person-rem per Ryr. 

Should a severe accident occur at a reactor located at the STP site, it is likely that Federal, 

State, and local officials would take various measures including limiting access to contaminated 

areas and interdiction to reduce exposures. In addition, the distance between the STP site and 

Matagorda Bay would reduce the aquatic food pathway dose risk below the risk estimated 

above. Considering the likelihood of interdiction and the distance from the STP site to 

Matagorda Bay, the NRC staff concludes that the population dose risk from the surface water 

pathways at the STP site is likely to be a small fraction of the air pathway risk. 
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NUREG-1937 5-110 February 2011 

5.11.2.3 Groundwater Pathway 

The groundwater pathway involves a reactor core melt, reactor vessel failure, and penetration of 

the floor (basemat) below the reactor vessel. Ultimately, core debris reaches the groundwater 

where soluble radionuclides are transported with the groundwater. The MACCS2 code does not 

evaluate the environmental risks associated with severe accident releases of radioactive 

material to groundwater. In the GEIS (NUREG-1437) (NRC 1996a), the NRC staff assumes a 

1 x 10-4 Ryr-1 probability of occurrence of a severe accident with a basemat melt-through leading 

to potential groundwater contamination, and concludes that groundwater contribution to risk is 

generally a small fraction of the risk attributable to the atmospheric pathway. 

The NRC staff has re-evaluated its assumption of a 1 x 10-4 Ryr-1 probability of a basemat meltthrough. The staff believes that the 1 x 10-4 probability is too large for new plants. New 

designs include features to reduce the probability of basemat melt-through in the event of a core 

melt accident. The probability of core melt with basemat melt-through should be no larger 

than the total CDF estimate for the reactor. Table 5-17 presents a total CDF estimate of 

1.56 x 10-7 Ryr-1 for the ABWR reactor. NUREG-1150 indicates that the conditional probability 

of a basemat melt-through ranges from 0.05 to 0.25 for current-generation reactors. Further, 

the ABWR severe accident release sequences that might be expected to involve core-concrete 

interactions have frequencies of less than 1 x 10-8 Ryr-1. On this basis, the NRC staff believes 

that a basemat melt-through probability of 1 x 10-7 Ryr-1 is reasonable and still conservative. 

The groundwater pathway is more tortuous and affords more time for implementing protective 

actions than the air pathway and, therefore, results in a lower risk to the public. As a result, the 

NRC staff concludes that the risks associated with releases to groundwater are sufficiently small 

that they would not have a significant effect on determination of suitability of the STP site. 

5.11.2.4 Summary 

The NRC staff reviewed the risk analyses in the ER, FSAR, and DCD for the purpose of 

determining the potential environmental impacts of severe accidents. Based on this review, the 

NRC staff concludes that the overall severe accident risk for proposed STP Units 3 and 4 is low. 

The NRC staff is currently reviewing the risk analyses presented in the FSAR to confirm this 

conclusion and determine compliance with the NRC’s safety regulations (10 CFR 52.79) and the 

Commission’s safety goals. The results of that review will be presented in the Safety Evaluation 

Report prepared by the staff regarding the COL application. The NRC staff also conducted a 

confirmatory analysis of the probability-weighted consequences of severe accidents for 

proposed STP Units 3 and 4 using the MACCS2 code. The results of both the STPNOC 

analysis and the NRC staff analysis indicate that the environmental risks associated with severe 

accidents if two ABWR reactors were to be located at the STP site would be small compared to 

risks associated with operation of the current-generation reactors at the STP and other sites. 

On these bases, the NRC staff concludes that the environmental impact of the probability-
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February 2011 5-111 NUREG-1937 

weighted consequences of severe accidents at the STP site would be SMALL for the proposed 

ABWRs. 

5.11.3 Severe Accident Mitigation Alternatives 

STPNOC has applied for COLs to construct and operate two ABWRs at the STP site. The 

ABWR design (see Appendix A to Part 52–Design Certification Rule for the U.S. Advanced 

Boiling Water Reactor) incorporates many features intended to reduce severe accident CDFs 

and the risks associated with severe accidents. The effectiveness of the ABWR design 

features is evident in Table 5-18 and Table 5-19, which compare CDFs and severe accident 

risks for the ABWR with CDFs and risks for current-generation reactors including existing 

STP Units 1 and 2. CDFs and risks have generally been reduced by a factor of 100 or more 

when compared to the existing units. 

The purpose of the evaluation of severe accident mitigation alternatives (SAMAs) is to 

determine whether there are severe accident mitigation design alternatives (SAMDAs) or 

procedural modifications or training activities that can be justified to further reduce the risks of 

severe accidents (NRC 2000). Consistent with the direction from the Commission to consider 

the SAMDAs at the time of certification, the ABWR vendor (GE 1994) and the NRC staff, in its 

environmental assessment (EA) accompanying the rule (NRC 1996b), have considered a 

design alternatives for a ABWR at a generic site. The NRC staff incorporates that EA into this 

EIS by reference. 

On these bases, the NRC staff concluded (NRC 1996b): 

Because the ABWR design already includes numerous plant features designed to 

reduce core-damage frequency and risk, additional plant improvements would be 

unable to significantly reduce the risk of either internally or externally initiated events.... 

Moreover, with the features already incorporated in the ABWR design, the ability to 

estimate core-damage frequency and risk approaches the limitations of probabilistic 

techniques. ... Although improvements in these areas may introduce additional 

contributors to core-damage frequency and risk estimates, the NRC staff does not 

expect that they would be significant in absolute terms. 

Further, 10 CFR Part 52 Appendix A Section VI(B)(7) provides resolution for: 

All environmental issues concerning severe accident mitigation design alternatives 

associated with the information in the NRC's final environmental assessment for the 

ABWR design and Revision 1 of the technical support document for the ABWR, dated 

December 1994, for plants referencing this appendix whose site parameters are within 

those specified in the technical support document. 
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NUREG-1937 5-112 February 2011 

In Revision 4 of the COL application (STPNOC 2010a), STPNOC incorporated by reference its 

proposed amendment to the ABWR design certification (STPNOC 2009i). STPNOC’s 

application includes proposed design modifications to address the ability of the ABWR design to 

withstand aircraft impacts as required by 10 CFR 50.150. STPNOC’s ER addressing the 

impacts of the proposed amendment on the SAMDA evaluation concludes that the proposed 

design changes provide a net risk reduction over the existing ABWR design; however, the 

quantitative effect of these changes on the probabilistic risk assessment is small (STPNOC 

2009i). Therefore, the ER further concluded, no SAMDA became cost beneficial as a result of 

the proposed design changes. The NRC staff reviewed the amendment application and 

supporting ER and concluded in a draft Environmental Assessment (EA) that the proposed 

changes would result in small changes in the CDF of the existing ABWR design (76 FR 3540). 

Therefore, the NRC staff further concluded in the EA, the proposed design changes would not 

alter the original SAMDA evaluation or the conclusions regarding SAMDAs presented in the final 

EA issued with the ABWR design certification rule (NRC 1996b). These conclusions also apply 

to the STPNOC COL application environmental review. 

In Section 7.3 of its ER, STPNOC reasserted the reactor vendor’s claim that there were no 

SAMDAs that would be cost beneficial. STPNOC did not do a STP site-specific evaluation of 

design alternatives. However, in ER Section 7.3.3, STPNOC did assess the maximum benefit 

that would accrue if a single procedural or training alternative could eliminate all remaining risk 

associated with the ABWR design by updating the analysis submitted for design certification 

(GE 1994) with STP site specific information and procedures set forth in NUREG/BR-0184 

(NRC 1997b). STPNOC determined that the maximum benefit at the STP site would be less 

than $20,000. A more realistic assessment would show that the potential benefit would be 

substantially less than the maximum because no alternative can reduce the remaining risk 

to zero. 

In addition, in ER Section 7.5S, STPNOC expanded the SAMDA analysis to explicitly consider 

the impact of an accident at Unit 3 or 4 on the other ABWR unit and on Units 1 and 2. The 

increase in monetized risk due to explicitly considering the impacts on the unaffected units is not 

sufficient to make any of the ABWR SAMDAs cost beneficial. 

The NRC staff has limited its review to a determination of whether or not the STP site 

characteristics are within the site parameters specified in the ABWR technical support document 

(GE 1994). The technical support document does not contain a specific list of site parameters. 

However, the population dose risk is given as 4.5 x 10-3 person-rem per year. The population 

dose risk is based on release characteristics including amount and probability, meteorological 

conditions, and population distribution and is, therefore, the appropriate site parameter for 

purposes of comparison. 

STPNOC evaluated the population dose risk for the STP site using the MACCS2 code with site 

specific meteorological and population distribution. The population dose risk derived from the 
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February 2011 5-113 NUREG-1937 

site-specific analysis discussed in the ER and shown in Table 5-18 is 4.2 × 10-3 person-rem per 

Ryr. Independent review by the NRC staff confirmed this value. On this basis, the NRC staff 

concludes that the STP site characteristics are bounded by the site parameters considered 

during the ABWR design certification, and that the environmental issues related to the SAMDAs 

have been resolved by rule. 

SAMDAs are a subset of SAMAs. SAMAs also include procedural and training alternatives. 

STPNOC did not develop procedural and training alternatives. In its ER, STPNOC (2010a) 

states that “[e]valuation of specific administrative controls would occur when the proposed Units 

3 and 4 design is finalized and plant administrative processes and procedures are being 

developed.” Pursuant to regulatory requirements, procedures must be in place and training 

must be completed prior to loading fuel. 

5.11.4 Summary of Postulated Accident Impacts

The NRC staff evaluated the environmental impacts from DBAs and severe accidents for an 

ABWR at the STP site. Based on the information provided by STPNOC and NRC’s own 

independent review, the staff concludes that the potential environmental impacts (risks) from a 

postulated accident from the operation of the proposed Units 3 and 4 would be SMALL and 

additional mitigation would not be warranted. 

5.12 Measures and Controls to Limit Adverse Impacts During 

Operation 

In its evaluation of environmental impacts during operation of proposed Units 3 and 4, the 

review team relied on STPNOC’s compliance with the following measures and controls that 

would limit adverse environmental impacts: 

• Compliance with applicable Federal, State, and local laws; ordinances, and regulations 

intended to prevent or minimize adverse environmental impacts, 

• Compliance with applicable requirements of permits or licenses required for operation of the 

new unit (e.g., Corps’ Section 404 Permit, TPDES permit), 

• Compliance with existing STP Unit 1 and 2 processes and/or procedures applicable to 

proposed Unit 3 and 4 environmental compliance activities for the STP site, 

• Compliance with STPNOC procedures applicable to environmental control and 

management, and 

• Implementation of BMPs. 

The review team considered these measures and controls in its evaluation of the impacts of 

plant operation. Table 5-20, which is the review team’s adaptation from sections of STPNOC’s 
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NUREG-1937 5-114 February 2011 

ER Table 5.10-1 (STPNOC 2010a), lists a summary of measures and controls to limit adverse 

impacts during operation proposed by STPNOC. 

Table 5-20. Summary of Proposed Measures and Controls to Limit Adverse Impacts During 

Operation 

Resource Category Specific Measures and Controls

Land-Use 

 There are no practical measures of mitigation for the approximately 300 ac of land 

that would be permanently dedicated to the plant until decommissioning. 

 Salt deposition could affect land use in the immediate vicinity of the cooling 

towers. The cooling towers would operate under rules and regulations governing 

these systems. 

STPNOC would maintain communication with local and regional government 

agencies to disseminate project information so they have the opportunity to plan 

accordingly for land-use impacts from operations workforce population growth and 

development for commercial and residential purposes. 

 All Federal, Texas, and local requirements and standards would be met regarding 

handling, transportation, and offsite land disposal of the solid waste at licensed 

facilities. 

Water-Related

Water-Use Impacts No mitigation would be required for pumping water from the Colorado River to the 

MCR. Total site groundwater demand would remain below that specified in the 

site groundwater permit, plus, the MCR and the Colorado River provide 

alternative water sources, if needed. Additional groundwater well(s) would be 

permitted under applicable CPGCD and TCEQ requirements, but would not 

require a request for an increase in the permit limit. Groundwater withdrawal 

would be from the deep confined Chicot Aquifer, and impacts from withdrawals to 

local wells in the Deep Aquifer would be achieved by following CPGCD 

requirements. Groundwater monitoring would be conducted as required by 

groundwater use permit. 
 Operational Impacts at the Proposed Site 

February 2011 5-115 NUREG-1937 

Table 5-20. (contd) 

Resource 

Category Specific Measures and Controls

Water Quality 

Impacts 

STPNOC would obtain a new or amended TPDES permit and comply with its 

discharge limits and monitoring requirements for discharges to the Colorado River. 

STPNOC would obtain a TPDES permit and comply with its discharge limits and 

monitoring requirements for blowdown from the MCR to the Colorado River. The 

MCR would be operated such that discharges would not be made when the river 

flow is less than 800 cubic ft per second (cfs) and the volume would not exceed 

12.5 percent of river flow, allowing dilution of the already diluted Units 3 and 4 

cooling system effluent by at least a factor of 8. 

Nonradioactive wastewater discharges would be in accordance with applicable 

TCEQ water quality standards. STPNOC would revise the existing SWPPP. The 

impacts due to the new impervious surfaces would be negligible due to BMPs.

Ecology 

Terrestrial 

Ecosystems 

Personnel performing transmission maintenance activities such as herbicide 

application would be trained in and hold Texas Department of Agriculture 

Commercial Pesticide Applicators Licenses, and all herbicide use would follow 

Federal, State, and local guidelines, and a Texas Department of Agriculture 

pesticide application permit 

Aquatic 

Ecosystems 

Closed-cycle cooling, intake screens parallel with river flow, and low approach 

velocity of traveling screens minimize impingement, entrainment, and entrapment. 

Discharges from the MCR to the Colorado River are expected to meet all permits 

(TPDES permit WQ0001908000). Chemical discharges would be monitored and 

concentrations are expected to be below criteria that are protective of aquatic life. 

Physical impacts, e.g., scouring, would be minimized by flow rate and direction of 

diffusers in the discharge facility. 

Aquatic resources in transmission corridors would be protected during 

maintenance by training chemical applicators to use appropriate chemicals and 

procedures for protection of aquatic life, as required by Texas Department of 

Agriculture Commercial Pesticide Applicators Licenses (Note: Maintenance would 

be performed by the transmission system owners, not STPNOC). 

Socioeconomic Impacts 

Physical Impacts STPNOC would obtain air and water permits and operate systems within permit 

limits and monitor emissions as required. 
Operational Impacts at the Proposed Site 

NUREG-1937 5-116 February 2011 

Table 5-20. (contd) 

Resource 

Category Specific Measures and Controls

Community Impacts STPNOC would maintain communication with local and regional governmental and 

non-government organizations in a timely manner so that they are aware of 

number of workers coming, and the timing of arrivals and departures to allow for 

community planning concerning potential change in housing, education, and other 

community services due to the influx of operations workers. 

 STPNOC would stagger outage schedules to prevent traffic congestion due to 

operations and outage worker commuting so only one unit would be down at a 

time. STPNOC would stagger arrival and departure times. 

Historic and 

Cultural 

Resources 

The Texas Historical Commission has indicated that ongoing operations and 

maintenance activities of STP Units 1 and 2 would have no effect on historic 

properties. Therefore it is anticipated that operations and maintenance activities 

associated with the proposed Units 3 and 4 should also have no effect on historic 

properties. 

Air Quality STPNOC would obtain air permits and operate systems within permit limits and 

monitor emissions as required. 

Operation of the proposed Units 3 and 4 cooling towers would result in water vapor 

plumes that would occur in each direction of the compass and would be spread 

over a wide area, reducing the time that the plume would be visible from any 

particular location. The average plume lengths would be short and would not be 

long enough to reach the site boundary in most directions. No mitigation would be 

required. 

Operation of the cooling towers could lead to minor shadowing, very small increase 

in precipitation, increases in ground-level humidity in the immediate vicinity, and 

salt deposition that is a fraction of the level needed to have visible effects on 

vegetation outside the site boundaries (greater than 1300 ft). No mitigation would 

be required.

Radiological Impacts of Normal Operation 

Radiation Doses to 

Members of the 

Public 

Calculated radiation doses to members of the public within NRC and EPA 

standards (10 CFR Part 20, Appendix I of 10 CFR Part 50, and 40 CFR Part 190). 

Radiological effluent and environmental monitoring programs would be 

implemented. 

Occupational 

Radiation Doses 

Estimated occupation doses are within NRC standards (10 CFR Part 20). 

Program would be implemented to maintain occupational doses ALARA 

(10 CFR Part 20). 

Radiation Doses to 

Biota Other Than 

Humans 

Calculated doses for biota are well within NCRP and IAEA guidelines. 

Radiological environmental monitoring program would be implemented. 
 Operational Impacts at the Proposed Site 

February 2011 5-117 NUREG-1937 

Table 5-20. (contd) 

Resource 

Category Specific Measures and Controls

Nonradioactive Waste 

Nonradioactive 

Waste System 

Impacts 

Reuse, recycle and reclaim solid waste and liquids as appropriate; otherwise use 

approved transporters and offsite disposal facilities. STPNOC has recycling and 

waste minimization programs currently in place for the increase in total volume of 

solid waste that would be generated at the STP site. 

Comply with applicable State and Federal hazardous waste and air quality 

regulations. Comply with TPDES permit, including implementing an SWPPP. 

 Disposal area(s) for nonradioactive waste would be at a permitted waste disposal 

facility with a land use designated for such activities. Disposal area would be 

operated under appropriate regulations and guidelines until such time an NRClicensed high-level waste disposal facility is constructed. At that time, the storage 

area could be restored for other uses. 

Mixed Waste 

Impacts 

STPNOC would update existing STP waste minimization plan for operation of 

proposed Units 3 and 4. 

STPNOC would implement materials handling and safety procedures as well as 

storage, shipment and emergency response procedures. 

STPNOC would revise Integrated Spill Contingency Plan as necessary to address 

handling and transport of mixed waste generated at Units 3 and 4. 

Accidents

Design Basis 

Accidents 

Calculated dose consequences of design basis accidents for the ABWR at the STP 

site were found to be within regulatory limits. 

Severe Accidents Calculated probability-weighted consequences of severe accidents for the ABWR 

at the STP site were found to be lower than the probability- weighted 

consequences for current operating reactors. 

 The STP site parameters are within the site parameters considered in the design 

certification review of severe accident mitigation design alternatives. Therefore, 

issues related to severe accident mitigation design alternatives are resolved. 

Procedural and training alternatives would be considered when procedures are 

developed. 

Nonradiological 

Health Impacts 

STPNOC would implement the existing STP industrial safety program at proposed 

Units 3 and 4 to mitigate impacts to worker health due to occupational injuries and 

illnesses. 

Source: STPNOC 2010a 
Operational Impacts at the Proposed Site 

NUREG-1937 5-118 February 2011 

5.13 Summary of Operational Impacts 

The review team’s evaluation of the environmental impacts of operations of proposed Units 3 

and 4 is summarized in Table 5-21. Impact levels are denoted in the table as SMALL, 

MODERATE, or LARGE as a measure of their expected adverse impacts. Socioeconomic 

categories for which the impacts are likely to be beneficial are noted as such in the Impact Level 

column. 

Table 5-21. Summary of Operational Impacts at the Proposed Units 3 and 4 Site 

Resource Category Comments Impact Level

Land-Use Impacts

 Site No adverse impacts projected. SMALL 

 Transmission Lines and 

 Offsite Areas 

No new offsite transmission corridors. Some new 

offsite housing and retail development expected. 

SMALL 

Water-Related Impacts

Water Use - Surface Water The addition of Units 3 and 4 would result in only 

slight decreases in Colorado River streamflow below 

the RMPF. 

SMALL 

Water Use - Groundwater Groundwater use would remain bounded by the 

existing groundwater use permit for existing STP 

Units 1 and 2. Groundwater use during operation 

would require the drilling and completion of at least 

one new well to obtain the capacity necessary to 

meet peak demands. Short-term maximum peak 

demands would be met, if necessary, by drawing 

from stored groundwater reserves, the MCR, or the 

Colorado River. 

SMALL 

Water Quality - Surface 

Water 

Stormwater runoff to onsite and offsite water bodies 

would be minimal because of implementation of a 

stormwater pollution prevention plan and use of 

BMPs. The 5°F isotherm plume, resulting from a 

bounding scenario of MCR discharge, would not 

completely block the Colorado River cross section. 

The minimum dilution in the Colorado River would 

be a factor of 8 and chemical or radiological 

contaminants present in the MCR discharge would 

be quickly transported downstream to the Matagorda 

Bay where they would be diluted even further. 

Water quality in the Colorado River would be 

minimally and temporarily affected by maintenance 

dredging of the RMPF. 

SMALL 
 Operational Impacts at the Proposed Site 

February 2011 5-119 NUREG-1937 

Table 5-21. (contd)

Resource Category Comments Impact Level

Water Quality - Groundwater Groundwater quality would remain substantially 

unchanged as a result of (1) the use of BMPs to 

contain and remove spills, (2) the change in 

contamination levels in the MCR that seep into the 

Upper Shallow Aquifer, and (3) the increased spatial 

distribution of pumping impacts by adding a well to 

the existing Deep Aquifer well network. 

SMALL 

Ecological Impacts

Terrestrial Ecosystems Impacts from operations of two new nuclear units, 

including the associated heat dissipation system, 

transmission lines, and right-of-way maintenance 

would be negligible. 

SMALL 

Aquatic Ecosystems Impacts to onsite aquatic ecosystems would be 

negligible. Impacts to aquatic ecosystems from 

operation of the RMPF and dredging would be 

minor. Impacts to aquatic organisms from 

operations of the MCR discharge would be 

detectable but would not noticeably alter important 

attributes of populations or communities. 

SMALL 

Socioeconomic Impacts

Physical Roads within the vicinity of STP would experience 

an increase in traffic at the beginning and the end of 

each operations shift and the beginning and end of 

each outage support shift. 

SMALL 

Demography The population of Matagorda County would grow by 

between 3 and 4% over a few years. 

SMALL 

Economic Impacts to 

Community 

Employment would be about 2400 higher in the 

region than without Units 3 and 4. Much of this 

activity could occur in Matagorda County. Impacts 

would be less noticeable in other counties. 

SMALL to 

LARGE 

beneficial 

Infrastructure and Community 

Services 

Additional operations workers would have a minor 

impact on the local road network and FM 521. 

The overall impact on housing demand and prices 

from plant operations over the expected 40-year 

operation of the plant in the region would likely be 

minimal for both Brazoria and Matagorda Counties.

SMALL 

Environmental Justice No environmental pathways or health and other 

preconditions of the minority and low-income 

population were found that would lead to adverse 

and disproportionate impacts. 

SMALL 
Operational Impacts at the Proposed Site 

NUREG-1937 5-120 February 2011 

Table 5-21. (contd)

Resource Category Comments Impact Level

Historic and Cultural Resources There are no known historic or cultural impacts at 

the STP site. STPNOC has agreed to follow 

procedures approved by the SHPO if historic or 

cultural resources are discovered during grounddisturbing activities. 

SMALL 

Meteorology and Air Quality 

Impacts 

Operation of the UHS cooling tower and intermittent 

operation of various diesel generators would be the 

primary emissions sources for air pollutants. 

SMALL 

Nonradiological Health Impacts There would be no observable nonradiological 

health impacts to the public from normal operation of 

the new units. Traffic accident impacts during 

operations would increase local traffic impacts by 

about 1%. 

SMALL 

Radiological Health Impacts 

 Members of the Public Doses to members of the public would be below 

NRC and EPA standards and there would be no 

observable health impacts (10 CFR Part 20, 

Appendix I to 10 CFR Part 50, 40 CFR Part 190). 

SMALL 

 Plant Workers Occupational doses to plant workers would be below 

NRC standards and program to maintain doses 

ALARA would be implemented. 

SMALL 

 Biota other than Humans Doses to biota other than humans would be well 

below NCRP and IAEA guidelines. 

SMALL 

Nonradioactive Waste Current STPNOC practices and procedures would 

help minimize waste generation at Units 3 and 4. 

SMALL 

Impacts of Postulated Accidents

Design Basis Accidents Impacts of design basis accidents would be well 

below regulatory limits. 

SMALL 

Severe Accidents Probability-weighted consequences of severe 

accidents would be lower than the probabilityweighted consequences for currently operating 

reactors. 

SMALL 

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Operational Impacts at the Proposed Site 

NUREG-1937 5-128 February 2011 

South Texas Project Nuclear Operating Company (STPNOC). 2009b. Letter from Scott Head, 

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Information.” Accession No. ML090270986. 

South Texas Project Nuclear Operating Company (STPNOC). 2009c. Letter from Scott Head, 

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Accession No. ML090270720. 

South Texas Project Nuclear Operating Company (STPNOC). 2009d. Letter from Mark. 

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South Texas Project Nuclear Operating Company (STPNOC). 2009e. Letter from Scott Head, 

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Additional Information.” Accession No. ML093310392. 

South Texas Project Nuclear Operating Company (STPNOC). 2009f. Letter from Scott Head, 

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South Texas Project Nuclear Operating Company (STPNOC). 2009g. Letter from Scott Head, 

STPNOC, to NRC, dated November 10, 2009, “Proposed Revision to the Environmental 

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South Texas Project Nuclear Operating Company (STPNOC). 2009h. Letter from Scott Head, 

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Accession No. ML102450261. 
 Operational Impacts at the Proposed Site 

February 2011 5-129 NUREG-1937 

South Texas Project Nuclear Operating Company (STPNOC). 2010c. South Texas Project 

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February 2011 5-133 NUREG-1937 

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February 2011 6-1 NUREG-1937 

6.0 Fuel Cycle, Transportation, and Decommissioning 

This chapter addresses the environmental impacts from (1) the uranium fuel cycle and solid 

waste management, (2) the transportation of radioactive material, and (3) the decommissioning 

of proposed Units 3 and 4 at the South Texas Project Electric Generating Station (STP) site. 

In its evaluation of uranium fuel cycle impacts from proposed Units 3 and 4 at the STP site, STP 

Nuclear Operating Company (STPNOC) used the U.S. Advanced Boiling Water Reactor 

(ABWR) advanced light water reactor (LWR) design. The capacity factor reported by STPNOC 

(2010a) for the ABWR design is 95 percent. The results reported here assume two units with a 

capacity factor of 95 percent. 

6.1 Fuel Cycle Impacts and Solid Waste Management 

This section discusses the environmental impacts from the uranium fuel cycle and solid waste 

management for the ABWR design. The environmental impacts of this design are evaluated 

against specific criteria for LWR designs in Title 10 of the Code of Federal Regulations 

(CFR) 51.51. 

The regulations in 10 CFR 51.51(a) state that 

Under §51.10, every environmental report prepared for the construction permit stage or 

early site permit stage or combined license stage of a light-water-cooled nuclear power 

reactor, and submitted on or after September 4, 1979, shall take Table S–3, Table of 

Uranium Fuel Cycle Environmental Data, as the basis for evaluating the contribution of the 

environmental effects of uranium mining and milling, the production of uranium 

hexafluoride, isotopic enrichment, fuel fabrication, reprocessing of irradiated fuel, 

transportation of radioactive materials and management of low-level wastes and high-level 

wastes related to uranium fuel cycle activities to the environmental costs of licensing the 

nuclear power reactor. Table S–3 shall be included in the environmental report and may 

be supplemented by a discussion of the environmental significance of the data set forth in 

the table as weighed in the analysis for the proposed facility. 

The ABWRs proposed for the STP site are light water reactors that would use uranium dioxide 

fuel; therefore, Table S–3 (10 CFR 51.51(b)) can be used to assess environmental impacts of 

the uranium fuel cycle. Table S–3 values are normalized for a reference 1000 megawatt 

electrical (MW(e)) LWR at an 80-percent capacity factor. The Table S–3 values are reproduced 

in Table 6-1. The power rating for the proposed Units 3 and 4 at the STP site is 2560 MW(e), 

assuming that two ABWRs would be located on the STP site (STPNOC 2010a), with a capacity 

factor of 95 percent. 
Fuel Cycle, Transportation, and Decommissioning 

NUREG-1937 6-2 February 2011 

Table 6-1. Table S–3 from 10 CFR 51.51(b), Table of Uranium Fuel Cycle Environmental 

Data(a)

Environmental Considerations Total

Maximum Effect per Annual Fuel Requirement or 

Reference Reactor Year of Model 1000 MW(e) LWR

Natural Resource Use 

Land (acres): 

 Temporarily committed(b)............................ 100

 Undisturbed area .................................... 79

 Disturbed area ........................................ 22 Equivalent to a 110-MW(e) coal-fired power plant. 

 Permanently committed ............................. 13 

 Overburden moved (millions of MT) .......... 2.8 Equivalent to a 95-MW(e) coal-fired power plant. 

 

Water (millions of gallons): 

 Discharged to air ....................................... 160 = 2% of model 1000-MW(e) LWR with cooling tower. 

 Discharged to water bodies ....................... 11,090 

 Discharged to ground ................................ 127 

 

 Total 11,377 <4% of model 1000 MW(e) with once-through cooling. 

Fossil fuel: 

 Electrical energy (thousands of MW-hr) .... 323 <5% of model 1000 MW(e) LWR output. 

 Equivalent coal (thousands of MT) ............ 118 Equivalent to the consumption of a 45-MW(e) coal-fired 

power plant. 

 Natural gas (millions of standard cubic 

 feet) 

135 <0.4% of model 1000 MW(e) energy output. 

Effluents--Chemical (MT) 

Gases (including entrainment):(c) 

 SOx 4400 

 NOx

(d) 1190 Equivalent to emissions from 45 MW(e) coal-fired plant for 

a year. 

 Hydrocarbons ............................................. 14 

 CO 29.6 

 Particulates ................................................. 1154 

Other gases: 

 F 0.67 Principally from uranium hexafluoride (UF6) production, 

enrichment, and reprocessing. The concentration is 

within the range of state standards–below level that has 

effects on human health. 

 HCI 0.014 

Liquids: 

 SO4

-

 9.9 From enrichment, fuel fabrication, and reprocessing 

steps. Components that constitute a potential for adverse 

environmental effect are present in dilute concentrations 

and receive additional dilution by receiving bodies of 

water to levels below permissible standards. The 

constituents that require dilution and the flow of dilution 

water are: NH3—600 cfs, NO3—20 cfs, Fluoride—70 cfs. 

 NO3

-

 25.8

 Fluoride 12.9

 Ca++ 5.4

 Cl− 8.5

 Na+ 12.1

 NH3 10

 Fe 0.4
 Fuel Cycle, Transportation, and Decommissioning 

February 2011 6-3 NUREG-1937 

Table 6-1. (contd)

Environmental Considerations Total

Maximum Effect per Annual Fuel Requirement or 

Reference Reactor Year of Model 1000 MW(e) LWR

 Tailings solutions (thousands of MT) .......... 240 From mills only–no significant effluents to environment. 

 Solids 91,000 Principally from mills–no significant effluents to 

environment. 

Effluents–Radiological (curies) 

Gases (including entrainment): 

 Rn-222 Presently under reconsideration by the Commission. 

 Ra-226 0.02 

 Th-230 0.02 

 Uranium 0.034 

 Tritium (thousands) ..................................... 18.1 

 C-14 24 

 Kr-85 (thousands) ....................................... 400 

 Ru-106 0.14 Principally from fuel reprocessing plants. 

 I-129 1.3 

 I-131 0.83 

 Tc-99 Presently under consideration by the Commission. 

 Fission products and transuranics .............. 0.203 

Liquids: 

 Uranium and daughters .............................. 2.1 Principally from milling–included tailings liquor and 

returned to ground–no effluents; therefore, no effect on 

environment. 

 Ra-226 0.0034 From UF6 production. 

 Th-230 0.0015 

 Th-234 0.01 From fuel fabrication plants–concentration 10 percent of 

10 CFR Part 20 for total processing 26 annual fuel 

requirements for model LWR. 

 Fission and activation products .................. 5.9 x 10−6

Solids (buried onsite): 

 Other than high level (shallow) ................... 11,300 9100 Ci comes from low-level reactor wastes and 1500 Ci 

comes from reactor decontamination and 

decommissioning—buried at land burial facilities. 600 Ci 

comes from mills—included in tailings returned to ground. 

Approximately 60 Ci comes from conversion and spent 

fuel storage. No significant effluent to the environment. 

 TRU and HLW (deep) ................................. 1.1 x 107 Buried at Federal Repository. 

Effluents—thermal (billions of British thermal 

units) 

4063 <5% of model1000-MW(e) LWR. 
Fuel Cycle, Transportation, and Decommissioning 

NUREG-1937 6-4 February 2011 

Table 6-1. (contd)

Environmental Considerations Total

Maximum Effect per Annual Fuel Requirement or 

Reference Reactor Year of Model 1000 MW(e) LWR

Transportation (person-rem): 

 Exposure of workers and general public ..... 2.5 

Occupational exposure (person-rem) ................ 22.6 From reprocessing and waste management. 

(a) In some cases where no entry appears it is clear from the background documents that the matter was addressed and that, in 

effect, the table should be read as if a specific zero entry had been made. However, other areas are not addressed at all in 

the table. Table S–3 does not include health effects from the effluents described in the table, or estimates of releases of 

radon-222 from the uranium fuel cycle or estimates of technetium-99 released from waste management or reprocessing 

activities. These issues may be the subject of litigation in the individual licensing proceedings. 

Data supporting this table are given in the “Environmental Survey of the Uranium Fuel Cycle,” WASH-1248 (AEC 1974); the 

“Environmental Survey of the Reprocessing and Waste Management Portion of the LWR Fuel Cycle,” NUREG-0116 (Supp.1 

to WASH-1248) (NRC 1976); the “Public Comments and Task Force Responses Regarding the Environmental Survey of the 

Reprocessing and Waste Management Portions of the LWR Fuel Cycle,” NUREG-0216 (Supp. 2 to WASH-1248) 

(NRC 1977b); and in the record of the final rulemaking pertaining to Uranium Fuel Cycle Impacts from Spent Fuel 

Reprocessing and Radioactive Waste Management, Docket RM-50-3. The contributions from reprocessing, waste 

management, and transportation of wastes are maximized for either of the two fuel cycles (uranium only and no recycle). The 

contribution from transportation excludes transportation of cold fuel to a reactor and of irradiated fuel and radioactive wastes 

from a reactor, which are considered in Table S–4 of Sec. 51.20(g). The contributions from the other steps of the fuel cycle 

are given in columns A-E of Table S–3A of WASH-1248. 

(b) The contributions to temporarily committed land from reprocessing are not prorated over 30 years, because the complete 

temporary impact accrues regardless of whether or not the plant services one reactor for one year or 57 reactors for 30 years. 

(c) Estimated effluents based upon combustion of equivalent coal for power generation. 

(d) 1.2% from natural gas use and process.

Specific categories of environmental considerations are included in Table S–3 (see Table 6-1). 

These categories relate to land use, water consumption and thermal effluents, radioactive 

releases, burial of transuranic and high-level and low-level wastes, and radiation doses from 

transportation and occupational exposures. In developing Table S–3, the U.S. Nuclear 

Regulatory Commission (NRC) staff considered two fuel cycle options that differed in the 

treatment of spent fuel removed from a reactor. The “no-recycle” option treats all spent fuel as 

waste to be stored at a Federal waste repository, whereas, the “uranium only recycle” option 

involves reprocessing spent fuel to recover unused uranium and return it to the system. Neither 

cycle involves the recovery of plutonium. The contributions in Table S–3 resulting from 

reprocessing, waste management, and transportation of wastes are maximized for both of the 

two fuel cycles (uranium only and no-recycle); that is, the identified environmental impacts are 

based on the cycle that results in the greater impact. The uranium fuel cycle is defined as the 

total of those operations and processes associated with provision, utilization, and ultimate 

disposition of fuel for nuclear power reactors. 

In 1978, the Nuclear Non-Proliferation Act of 1978 (22 USC 3201, et seq.) was enacted. This 

law significantly impacted the disposition of spent nuclear fuel by deferring indefinitely the 

commercial reprocessing and recycling of spent fuel produced in the U.S. commercial nuclear 

power program. While the ban on the reprocessing of spent fuel was lifted during the Reagan 

administration, economic circumstances changed, reserves of uranium ore increased, and the 

stagnation of the nuclear power industry provided little incentive for industry to resume 
 Fuel Cycle, Transportation, and Decommissioning 

February 2011 6-5 NUREG-1937 

reprocessing. During the 109th Congress, the Energy Policy Act of 2005 was enacted. It 

authorized the U.S. Department of Energy (DOE) to conduct an advanced fuel recycling 

technology research and development program to evaluate proliferation-resistant fuel recycling 

and transmutation technologies that minimize environmental or public health and safety 

impacts. Consequently, while Federal policy does not prohibit reprocessing, additional DOE 

efforts would be required before commercial reprocessing and recycling of spent fuel produced 

in the U.S. commercial nuclear power plants could commence. 

The no-recycle option is presented schematically in Figure 6-1. Natural uranium is mined in 

either open-pit or underground mines or by an in situ leach solution mining process. In situ 

leach mining, presently the primary form of mining in the United States, involves injecting a 

lixiviant solution into the uranium ore body to dissolve uranium and then pumping the solution to 

the surface for further processing. The ore or in situ leach solution is transferred to mills where 

it is processed to produce “yellowcake” (U3O8). A conversion facility prepares the U3O8 by 

converting it to uranium hexafluoride (UF6), which is then processed by an enrichment facility to 

increase the percentage of the more fissile isotope uranium-235 and decrease the percentage 

of the non-fissile isotope uranium-238. At a fuel fabrication facility, the enriched uranium, which 

is approximately five percent uranium-235, is then converted to uranium oxide (UO2). The UO2

is pelletized, sintered, and inserted into tubes to form fuel assemblies, which are destined to be 

placed in a reactor to produce power. When the content of the uranium-235 reaches a point 

where the nuclear reaction has become inefficient with respect to neutron economy, the fuel 

assemblies are withdrawn from the reactor as spent fuel. After being stored onsite for sufficient 

time to allow for short-lived fission product decay and to reduce the heat generation rate, the 

fuel assemblies would be transferred to a waste repository for internment. Disposal of spent 

fuel elements in a repository constitutes the final step in the no-recycle option. 

The following assessment of the environmental impacts of the fuel cycle as related to the 

operation of the proposed project is based on the values given in Table S–3 (Table 6-1) and the 

NRC staff’s analysis of the radiological impact from radon-222 and technetium-99. In 

NUREG-1437, Generic Environmental Impact Statement for License Renewal of Nuclear Plants 

(GEIS) (NRC 1996, 1999),(a) the NRC staff provides a detailed analysis of the environmental 

impacts from the uranium fuel cycle. Although NUREG-1437 is specific to the impacts related to 

license renewal, the information is relevant to this review because the advanced LWR design 

considered here uses the same type of fuel; the NRC staff’s analyses in Section 6.2.3 of 

NUREG-1437 are summarized and provided here. 

The fuel cycle impacts in Table S–3 are based on a reference 1000-MW(e) LWR operating at an 

annual capacity factor of 80 percent for a net electric output of 800 MW(e). In the following 

 

(a) NUREG-1437 was originally issued in 1996. Addendum 1 to NUREG-1437 was issued in 1999. 

Hereafter, all references to NUREG-1437 include NUREG-1437 and its Addendum 1. 
Fuel Cycle, Transportation, and Decommissioning 

NUREG-1937 6-6 February 2011 

Figure 6-1. The Uranium Fuel Cycle: No-Recycle Option (derived from NRC 1999)

review and evaluation of the environmental impacts of the fuel cycle, the NRC staff considered 

the capacity factor of 95 percent with a total net electric output of 1280 MW(e) for each of the 

proposed Units 3 and 4 at the STP site for a total of 2560 MW(e) (STPNOC 2010a) this is about 

3.2 times (i.e., 2560 MW(e) divided by 800 MW(e) yields 3.2) the impact values in Table S–3 

(see Table 6-1). Throughout this chapter, this will be referred to as the 1000-MW(e) LWRscaled model, 2560 MW(e) for the site. 

Recent changes in the fuel cycle may have some bearing on environmental impacts; however, 

as discussed below, the staff is confident that the contemporary fuel cycle impacts are below 

those identified in Table S–3. This is especially true in light of the following recent fuel cycle 

trends in the United States: 

• Increasing use of in-situ leach uranium mining, which does not produce mine tailings. 

• Transitioning of U.S. uranium enrichment technology from gaseous diffusion to gas 

centrifuge. The latter centrifuge process uses only a small fraction of the electrical energy 
 Fuel Cycle, Transportation, and Decommissioning 

February 2011 6-7 NUREG-1937 

per separation unit compared to gaseous diffusion. (U.S. gaseous diffusion plants relied on 

electricity derived mainly from the burning of coal.) 

• Current LWRs use nuclear fuel more efficiently due to higher fuel burnup. Therefore, less 

uranium fuel per year of reactor operation is required than in the past to generate the same 

amount of electricity. 

• Fewer spent fuel assemblies per reactor-year are discharged, hence the waste 

storage/repository impact is lessened. 

The values in Table S–3 were calculated from industry averages for the performance of each 

type of facility or operation within the fuel cycle. Recognizing that this approach meant that 

there would be a range of reasonable values for each estimate, the NRC staff used an approach 

of choosing the assumptions or factors to be applied so that the calculated values would not be 

underestimated. This approach was intended to ensure that the actual environmental impacts 

would be less than the quantities shown in Table S–3 for all LWR nuclear power plants within 

the widest range of operating conditions. Many subtle fuel cycle parameters and interactions 

were recognized by the NRC staff as being less precise than the estimates and were not 

considered or were considered but had no effect on the Table S–3 calculations. For example, 

to determine the quantity of fuel required for a year’s operation of a nuclear power plant in 

Table S–3, the NRC staff defined the model reactor as a 1000-MW(e) LWR reactor operating at 

80-percent capacity with a 12-month fuel reloading cycle and an average fuel burn-up of 

33,000 MWd/MTU. This is a “reactor reference year” or “reference reactor year” depending on 

the source (either Table S–3 or NUREG-1437), but it has the same meaning. The sum of the 

initial fuel loading plus all the reloads for the lifetime of the reactor can be divided by the now 

more likely 60-year lifetime (40-year initial license term and 20-year license renewal term) to 

obtain an average annual fuel requirement. This was done in NUREG-1437 for both boiling 

water reactors and pressurized water reactors; the higher annual requirement, 35 metric tons 

(MT) of uranium made into fuel for a boiling water reactor, was chosen in NUREG-1437 (NRC 

1996, 1999) as the basis for the reference reactor year. A number of fuel management 

improvements have been adopted by nuclear power plants to achieve higher performance and 

to reduce fuel and separative work (enrichment) requirements. Since Table S–3 was 

promulgated, these improvements have reduced the annual fuel requirement. 

Another change is the elimination of the U.S. restrictions on the importation of foreign uranium. 

Until recently, the economic conditions of the uranium market favored use of foreign uranium at 

the expense of the domestic uranium industry. These market conditions resulted in the closing 

of most U.S. uranium mines and mills, substantially reducing the environmental impacts in the 

United States from these activities. However, more recently the spot price of uranium has 

increased from $24 per pound in April 2005 to $135 per pound in July 2007 and has decreased 

to near $44 per pound as of April 2009 (UxC 2009). As a result, there is some renewed interest 

in uranium mining and milling in the United States and the NRC anticipates receiving multiple 
Fuel Cycle, Transportation, and Decommissioning 

NUREG-1937 6-8 February 2011 

license applications for uranium mining and milling in the next several years. The majority of 

these applications are expected to be for in situ leach solution mining that does not produce 

tailings. Factoring in changes to the fuel cycle suggests that the environmental impacts of 

mining and tail millings could drop to levels below those given in Table S–3; however, 

Table S–3 estimates have not been reduced for these analyses. 

Section 6.2 of NUREG-1437 discusses the sensitivity to recent changes in the fuel cycle on the 

environmental impacts in greater detail. 

6.1.1 Land Use 

The total annual land requirement for the fuel cycle supporting the 1000-MW(e) LWR-scaled 

model would be about 366 ac. Of this land requirement, approximately 42 ac are permanently 

committed and 324 ac are temporarily committed. A “temporary” land commitment is a 

commitment for the life of the specific fuel cycle plant (e.g., a mill, enrichment plant, or 

succeeding plants). Following completion of decommissioning, such land can be released for 

unrestricted use. “Permanent” commitments represent land that may not be released for use 

after plant shutdown and decommissioning because decommissioning activities do not result in 

removal of sufficient radioactive material to meet the limits in 10 CFR Part 20, Subpart E, for 

release of that area for unrestricted use. Of the 324 ac of temporarily committed land, 254 are 

undisturbed, and 70 ac are disturbed. In comparison, a coal-fired power plant using the same 

MW(e) output as the LWR-scaled model and using strip-mined coal requires the disturbance of 

about 640 ac per year for fuel alone. The NRC staff concludes that the impacts on land use to 

support the 1000-MW(e) LWR-scaled model would be SMALL. 

6.1.2 Water Use 

The principal water use for the fuel cycle supporting the 1000-MW(e) LWR-scaled model would 

be that required to remove waste heat from the power stations supplying electrical energy to the 

enrichment step of this cycle. Scaling from Table S–3, of the total annual water use of 

3.65 x 1010 gallons, about 3.56 x 1010 gallons are required for the removal of waste heat. Also 

scaling from Table S-3, other water uses involve the discharge to air (e.g., evaporation losses in 

process cooling) of about 5.13 x 108

 gallons per year and water discharged to the ground (e.g., 

mine drainage) of about 4.07 x 108

 gallons per year. The NRC staff concludes that the impacts 

on water use for these combinations of thermal loadings and water consumption would be 

SMALL. 

6.1.3 Fossil Fuel Impacts 

Electric energy and process heat are required during various phases of the fuel cycle process. 

Electric energy is usually produced by the combustion of fossil fuel at conventional power 

plants. Electric energy associated with the fuel cycle represents about 5 percent of the annual 
 Fuel Cycle, Transportation, and Decommissioning 

February 2011 6-9 NUREG-1937 

electric power production of the reference 1000-MW(e) LWR. Process heat is primarily 

generated by the combustion of natural gas. This gas consumption, if used to generate 

electricity, would be less than 0.4 percent of the electrical output from the model plant. 

The largest source of carbon dioxide (CO2) emissions associated with nuclear power is from the 

fuel cycle, not the operation of the plant, as indicated above and in Table S–3. The CO2 

emissions from the fuel cycle are about 5 percent of the CO2 emissions from an equivalent fossil 

fuel-fired plant. 

The largest use of electricity in the fuel cycle comes from the enrichment process. It appears 

that gas centrifuge (GC) technology is likely to eventually replace gaseous diffusion (GD) 

technology for uranium enrichment in the United States. The same amount of enrichment from 

a GC facility uses less electricity and therefore results in lower amounts of air emissions such as 

carbon dioxide than a GD facility. Therefore, the NRC staff concludes that the values for 

electricity use and air emissions in Table S-3 continue to be appropriately bounding values. In 

Appendix I, the NRC staff estimates that the carbon footprint of the fuel cycle to support a 

reference 1000 MW(e) LWR for a 40-year plant life is on the order of 17,000,000 metric tons of 

CO2 including a small contribution from other greenhouse gases. Scaling this footprint to the 

power level and capacity factor of STP Units 3 and 4, the review team estimates the carbon 

footprint for 40 years of fuel cycle emissions to be about 54,000,000 metric tons (an emission 

rate of about 1,400,000 metric tons annually, averaged over the period of operation) of CO2, as 

compared to a total United States annual emissions rate of 6,000,000,000 metric tons (EPA 

2010). 

On this basis, the NRC staff concludes that the fossil fuel impacts, including greenhouse gas 

emissions, from the direct and indirect consumption of electric energy for fuel cycle operations 

would be SMALL. 

6.1.4 Chemical Effluents 

The quantities of gaseous and particulate chemical effluents produced in fuel-cycle processes 

are given in Table S–3 (Table 6-1) for the reference 1000-MW(e) LWR and, according to 

WASH-1248 (AEC 1974), result from the generation of electricity for fuel cycle operations. The 

principal effluents are sulfur oxides, nitrogen oxides, and particulates. Table S–3 states that the 

fuel cycle for the reference 1000-MW(e) LWR requires 323,000 MW-hr of electricity. The fuel 

cycle for the 1000-MW(e) LWR scaled model would therefore require 1,033,600 MW-hr of 

electricity, or 0.025 percent of the 4.1 billion MW-hr of electricity generated in the United States 

in 2008 (DOE 2009). Therefore, the gaseous and particulate chemical effluents would add 

about 0.025 percent to the national gaseous and particulate chemical effluents for electricity 

generation. 
Fuel Cycle, Transportation, and Decommissioning 

NUREG-1937 6-10 February 2011 

Liquid chemical effluents produced in fuel cycle processes are related to fuel enrichment and 

fabrication and may be released to receiving waters. These effluents are usually present in 

dilute concentrations such that only small amounts of dilution water are required to reach levels 

of concentration that are within established standards. Table S–3 (Table 6-1) specifies the 

amount of dilution water required for specific constituents. In addition, all liquid discharges into 

the navigable waters of the United States from plants associated with the fuel cycle operations 

would be subject to requirements and limitations set by an appropriate Federal, State, Tribal, 

and local agencies. 

Tailings solutions and solids are generated during the milling process, but as Table S-3 

indicates, effluents are not released in quantities sufficient to have a significant impact on the 

environment. 

Based on the above analysis, the NRC staff concludes that the impacts of these gaseous, 

particulate, and liquid chemical effluents would be SMALL. 

6.1.5 Radiological Effluents 

Radioactive effluents estimated to be released to the environment from waste management 

activities and certain other phases of the fuel cycle process are set forth in Table S–3 

(Table 6-1). Using these effluents in NUREG-1437 (NRC 1996, 1999), the NRC staff calculated 

the 100-year environmental dose commitment to the U.S. population from the fuel cycle of one 

year of operation of the model 1000-MW(e) LWR. The total overall whole body gaseous dose 

commitment and whole body liquid dose commitment from the fuel cycle (excluding reactor 

releases and dose commitments because of exposure to radon-222 and technetium-99) were 

calculated to be approximately 400 person-rem and 200 person-rem, respectively. Scaling 

these dose commitments by a factor of about 3.2 for the 1000-MW(e) LWR-scaled model 

reactor would result in whole body dose commitment estimates of 1280 person-rem for gaseous 

releases and 640 person-rem for liquid releases. For both pathways, the estimated 100-year 

environmental dose commitment to the U.S. population would be approximately 1920 personrem for the 1000-MW(e) LWR-scaled model reactor. 

Currently, the radiological impacts associated with radon-222 and technetium-99 releases are 

not addressed in Table S–3. Principal radon releases occur during mining and milling 

operations and as emissions from mill tailings, whereas principal technetium-99 releases occur 

from gaseous diffusion enrichment facilities. STPNOC provided an assessment of radon-222 

and technetium-99 in its environmental report (ER) (STPNOC 2010a). STPNOC’s evaluation 

relied on the information discussed in NUREG-1437 (NRC 1996, 1999). 

In Section 6.2 of NUREG-1437 (NRC 1996, 1999), the NRC staff estimated the radon-222 

releases from mining and milling operations and from mill tailings for each year of operations of 

the reference 1000-MW(e) LWR. The estimated releases of radon-222 for the reference reactor 
 Fuel Cycle, Transportation, and Decommissioning 

February 2011 6-11 NUREG-1937 

year for the 1000-MW(e) LWR-scaled model reactor, or for the total electric power rating for the 

site for a year, are approximately 16,600 Ci. Of this total, about 78 percent would be from 

mining, 15 percent from milling operations, and 7 percent from inactive tails before stabilization. 

For radon releases from stabilized tailings, the NRC staff assumed that the LWR-scaled model 

reactor would result in an emission of 3.2 Ci per site year, (i.e., about 3.2 times the 

NUREG-1437 [NRC 1996, 1999] estimate for the reference reactor year). The major risks from 

radon-222 are from exposure to the bone and the lung, although there is a small risk from 

exposure to the whole body. The organ-specific dose-weighting factors from 10 CFR 20 

Subpart C were applied to the bone and lung doses to estimate the 100-year dose 

commitment from radon-222 to the whole body. The estimated 100-year environmental dose 

commitment from mining, milling, and tailings before stabilization for each site year (assuming 

the 1000-MW(e) LWR-scaled model) would be approximately 2950 person-rem to the whole 

body. From stabilized tailings piles, the estimated 100-year environmental dose commitment 

would be approximately 56 person-rem to the whole body. Additional insights regarding Federal 

policy/resource perspectives concerning institutional controls comparisons with routine radon222 exposure and risk and long-term releases from stabilized tailing piles are discussed in 

NUREG-1437 (NRC 1996, 1999). 

Also, as discussed in NUREG-1437, the NRC staff considered the potential doses associated 

with the releases of technetium-99. The estimated releases of technetium-99 for the reference 

reactor year for the 1000-MW(e) LWR-scaled model reactor are 0.022 Ci from chemical 

processing of recycled uranium hexafluoride before it enters the isotope enrichment cascade 

and 0.016 Ci into the groundwater from a repository. The major risks from technetium-99 are 

from exposure of the gastrointestinal tract and kidney, although there is a small risk from 

exposure to the whole body. Applying the organ-specific dose-weighting factors from 

10 CFR 20 Subpart C to the gastrointestinal tract and kidney doses, the total-body 100-year 

dose commitment from technetium-99 to the whole body was estimated to be 320 person-rem 

for the 1000-MW(e) LWR-scaled model reactor. 

Radiation protection experts assume that any amount of radiation may pose some risk of 

causing cancer or a severe hereditary effect, and that the risk is higher for higher radiation 

exposures. Therefore, a linear, no-threshold dose-response relationship assumption is used to 

describe the relationship between radiation dose and detriments such as cancer induction. 

A recent report by the National Research Council (2006), the Biological Effects of Ionizing 

Radiation (BEIR) VII report, uses the linear, no-threshold model as a basis for estimating the 

risks from low doses. This approach is accepted by the NRC as a conservative method for 

estimating health risks from radiation exposure, recognizing that the model may overestimate 

those risks. Based on this method, the NRC staff estimated the risk to the public from radiation 

exposure using the nominal probability coefficient for total detriment. The nominal probability 

coefficient for total detriment is a factor for the incidence of cancer and other health effects. 

This coefficient has the value of 570 fatal cancers, nonfatal cancers, and severe hereditary 
Fuel Cycle, Transportation, and Decommissioning 

NUREG-1937 6-12 February 2011 

effects per 1,000,000 person-rem, equal to 0.00057 effects per person-rem. The coefficient is 

taken from International Commission on Radiological Protection’s (ICRP) Publication 103 

(ICRP 2007). 

The nominal probability coefficient was multiplied by the sum of the estimated whole body 

population doses from gaseous effluents, liquid effluents, radon-222, and technetium-99 

discussed above (approximately 5300 person-rem/yr) to calculate that the U.S. population 

would incur a total of approximately 3 fatal cancers, nonfatal cancers, and severe hereditary 

effects annually. 

Radon-222 releases from tailings are indistinguishable from background radiation levels at a 

few miles from the tailings pile (at less than 0.6 mi in some cases) (NRC 1996). The public 

dose limit in the Environmental Protection Agency’s regulation, 40 CFR 190.10, is 25 mrem/yr to 

the whole body from the entire fuel cycle, but most NRC licensees have airborne effluents 

resulting in doses of less than 1 mrem/yr (61 FR 65120). 

In addition, at the request of the U.S. Congress, the National Cancer Institute conducted a study 

and published Cancer in Populations Living Near Nuclear Facilities in 1990 (NCI 1990). This 

report included an evaluation of health statistics around all nuclear power plants and several 

other nuclear fuel cycle facilities in operation in the United States in 1981; the report found “no 

evidence that an excess occurrence of cancer has resulted from living near nuclear facilities”. 

The contribution to the annual average dose received by an individual from fuel-cycle-related 

radiation and other sources as reported in a report published by the National Council on 

Radiation Protection and Measurements (NCRP) (NCRP 2009) is listed in Table 6-2. The 

nuclear fuel cycle contribution to an individual’s annual average radiation dose is extremely 

small (less than 0.1 mrem/yr) compared to the annual average background radiation dose 

(about 311 mrem/yr). 

Based on the analyses presented above, the NRC staff concludes that the environmental 

impacts of radioactive effluents from the fuel cycle are SMALL. 

6.1.6 Radiological Wastes 

The quantities of buried radioactive waste material (low-level, high-level, and transuranic 

wastes) are specified in Table S–3 (Table 6-1). 

For low-level waste (LLW) disposal at land burial facilities, the Commission notes in Table S–3 

that there would be no significant radioactive releases to the environment. STP Units 1 and 2 

can no longer dispose of Class B and C LLW at the Energy Solutions site in Barnwell, South 

Carolina. Proposed Units 3 and 4, if in operation, would also not be able to dispose of these 

wastes at Barnwell. However, Class A LLW can be shipped to the Energy Solutions site in 

Clive, Utah. Other disposal sites may be available by the time the two new units would 
 Fuel Cycle, Transportation, and Decommissioning 

February 2011 6-13 NUREG-1937 

Table 6-2. Comparison of Annual Average Dose Received by an Individual from All Sources 

Source Dose (mrem/yr)(a) Percent of Total

Ubiquitous background Radon & Thoron 

Space 

Terrestrial 

Internal (body) 

Total background sources 

228 

33 

21 

29 

311 

37 

5 

3 

5 

50 

Medical Computed tomography 

Medical x-ray 

Nuclear medicine 

Total medical sources 

147 

76 

77 

300 

24 

12 

12 

48 

Consumer Construction materials, 

smoking, air travel, mining, 

agriculture, fossil fuel 

combustion 

13 2 

Other Occupational 

Nuclear fuel cycle 

0.5(b)

0.05(c)

0.1 

0.01 

Total 624 

Source: NCRP 2009. 

(a) NCRP Report 160 table expressed doses in mSv/yr (1 mSv/yr equals 100 mrem/yr). 

(b) Occupational dose is regulated separately from public dose and is provided here for informational purposes. 

(c) Estimated using 153 person-Sv/yr from Table 6.1 of NCRP 160 and a 2006 US population of 300 million.

become operational. For example, on September 10, 2009, the Texas Commission on 

Environmental Quality (TCEQ) (TCEQ 2009) issued Radioactive Material License R04100 to 

Waste Control Specialists, LLC (WCS) for the construction of a low-level waste facility in 

Andrews County, Texas. The facility will accept Class A, B, and C LLW. Once WCS completes 

construction and satisfies any operational-related conditions imposed by the TCEQ, the facility 

may begin to receive and dispose of LLW (TCEQ 2009). Construction activities have begun, 

and disposal activities are estimated to begin in late 2011 (Valhi 2011). Thus, it is likely that this 

facility would be available to the STP for disposal of LLW. In addition, the industry is 

investigating alternate disposal pathways for Class B and C LLW including (1) compaction and 

storage at offsite vendor locations until disposal is secured, and (2) blending of waste types with 

subsequent disposal at available disposal sites. 

The NRC staff anticipates that licensees would temporarily store Class B and C LLW onsite until 

offsite storage locations are available. Several operating nuclear power plants have 

successfully increased onsite storage capacity in the past in accordance with existing NRC 

regulations. This extended waste storage onsite resulted in no significant increase in dose to 

the public. In addition, the NRC issued Regulatory Issue Summary 2008-12 (NRC 2008), which 

included guidance for the extended onsite interim storage of LLW; this guidance addressed the 
Fuel Cycle, Transportation, and Decommissioning 

NUREG-1937 6-14 February 2011 

storage of waste in a manner that minimizes potential exposure to workers which may require 

adding shielding and storing waste in packaging compatible with the waste composition 

(e.g., chemical and thermal properties). 

The NRC staff concluded in NUREG-1437 (NRC 1996, 1999) that the radiological impacts from 

LLW storage would be small and fall within current regulatory requirements. Although 

NUREG-1437 is for license renewal activities, the staff concludes that the evaluation can be 

applied to new reactors because radwaste technology and operations will be similar to existing 

operating reactors. In NUREG-1437 (Section 6.4.4.2), the NRC staff concluded that there 

should be no significant issues or environmental impacts associated with interim storage of LLW 

generated by nuclear power plants. Interim storage facilities would be used until these wastes 

could be safely shipped to licensed disposal facilities. STPNOC’s resolution of LLW disposal 

issues for the existing STP Units 1 and 2 could also be implemented for the proposed Units 3 

and 4. 

Current national policy, as found in the Nuclear Waste Policy Act (42 USC 10101, et seq.) 

mandates that high-level and transuranic wastes are to be buried at a deep geologic repository, 

such as the proposed repository at Yucca Mountain, Nevada. No release to the environment is 

expected to be associated with deep geologic disposal because it has been assumed that all of 

the gaseous and volatile radionuclides contained in the spent fuel are released to the 

atmosphere before the disposal of the waste. In NUREG-0116 (NRC 1976), which provides 

background and context for the high-level and transuranic Table S–3 values established by the 

Commission, the NRC staff indicates that these high-level and transuranic wastes will be buried 

and will not be released to the environment. 

As a part of the Table S–3 rulemaking the NRC staff evaluated, along with more conservative 

assumptions, the zero release assumption associated with waste burial in a repository: the NRC 

reached an overall generic determination that fuel cycle impacts would not be significant. In 

1983, the Supreme Court affirmed the NRC’s position that the zero release assumption was 

reasonable in the context of the Table S–3 rulemaking to address generically the impacts of the 

uranium fuel cycle in individual reactor licensing proceedings (Baltimore Gas & Electric v.

Natural Resources Defense Council). 

Further, in the Commission’s Waste Confidence Decision and Rule (10 CFR 51.23(a)) 

(75 FR 81032), the Commission has made the generic determination that “if necessary, spent 

fuel generated in any reactor can be stored safely and without significant environmental impacts 

for at least 60 years beyond the licensed life for operation (which may include the term of a 

revised or renewed license) of that reactor in a combination of storage in its spent fuel storage 

basin and at either onsite or offsite independent spent fuel storage installations. Further, the 

Commission believes there is reasonable assurance that sufficient mined geologic repository 

capacity will be available to dispose of the commercial high-level radioactive waste and spent 

fuel generated in any reactor when necessary.” In addition, 10 CFR 51.23(b) applies the 
 Fuel Cycle, Transportation, and Decommissioning 

February 2011 6-15 NUREG-1937 

generic determination in Section 51.23(a) to provide that “no discussion of any environmental 

impact of spent fuel storage in reactor facility storage pools or independent spent fuel storage 

installations (ISFSI) for the period following the term of the . . . reactor combined license or 

amendment. . .is required in any . . . environmental impact statement . . . prepared in connection 

with . . . the issuance or amendment of a combined license for a nuclear power reactors under 

parts 52 or 54 of this chapter.”

In the context of operating license renewal, Sections 6.2 and 6.4 of NUREG-1437 (NRC 1996) 

provide additional description of the generation, storage, and ultimate disposal of LLW, mixed 

waste, and high-level waste (HLW) including spent fuel from power reactors. These sections 

conclude that environmental impacts from these activities are small. For the reasons stated 

above, the NRC staff concludes that the environmental impacts of radioactive waste storage 

and disposal associated with Units 3 and 4 are SMALL. 

6.1.7 Occupational Dose 

The annual occupational dose attributable to all phases of the fuel cycle for the 1000-MW(e) 

LWR-scaled model is about 1920 person-rem. This is based on a 600 person-rem occupational 

dose estimate attributable to all phases of the fuel cycle for the model 1000 MW(e) LWR (NRC 

1996, 1999). The environmental impact from this occupational dose is considered SMALL 

because the dose to any individual worker would be maintained within the limits of 10 CFR 20, 

Subpart C, which is 5 rem/yr. 

6.1.8 Transportation 

The transportation dose to workers and the public totals about 2.5 person-rem annually for the 

reference 1000-MW(e) LWR per Table S–3 (Table 6-1). This corresponds to a dose of 

8 person-rem for the 1000-MW(e) LWR-scaled model. For comparative purposes, the 

estimated collective dose from natural background radiation to the current population within 

50 mi of the STP site is about 75,000 person-rem/yr (STPNOC 2010a). Based on this 

comparison, the NRC staff concludes that environmental impacts of transportation would be 

SMALL. 

6.1.9 Conclusion 

The NRC staff evaluated the environmental impacts of the uranium fuel cycle, as given in 

Table S–3 (Table 6-1), considered the effects of radon-222 and technetium-99, and 

appropriately scaled the impacts for the 1000-MW(e) LWR-scaled model. The NRC staff also 

evaluated the environmental impacts of greenhouse gas emissions from the uranium fuel cycle 

and appropriately scaled the impacts for the 1000-MW(e) LWR-scaled model. Based on these 

evaluations, the NRC staff concludes that the impacts of the uranium fuel cycle would be 

SMALL. 
Fuel Cycle, Transportation, and Decommissioning 

NUREG-1937 6-16 February 2011 

6.2 Transportation Impacts 

This section addresses both the radiological and nonradiological environmental impacts from 

normal operating and accident conditions resulting from (1) shipment of unirradiated fuel to the 

STP site and the alternative sites, (2) shipment of irradiated (spent) fuel to a monitored 

retrievable storage facility or a permanent repository, and (3) shipment of low-level radioactive 

waste and mixed waste to offsite disposal facilities. For the purposes of these analyses, the 

NRC staff considered the proposed Yucca Mountain, Nevada, site as a surrogate destination for 

a permanent repository. The impacts evaluated in this section for two new nuclear generating 

units at the STP site are appropriate to characterize the alternative sites discussed in Section 

9.3 of this environmental impact statement (EIS). Alternative sites evaluated in this EIS include 

the existing STP site (proposed), and alternative sites at Allens Creek, Red 2, and Trinity 2. 

There is no meaningful differentiation among the proposed and the alternative sites regarding 

the radiological and nonradiological environmental impacts from normal operating and accident 

conditions and are not discussed further in Chapter 9. 

The NRC performed a generic analysis of the environmental effects of transportation of fuel and 

waste to and from LWRs in the Environmental Survey of Transportation of Radioactive Materials 

To and From Nuclear Power Plants, WASH-1238 (AEC 1972) and in a supplement to 

WASH-1238, NUREG-75/038 (NRC 1975) and found the impact to be SMALL. These 

documents provided the basis for Table S–4 in 10 CFR 51.52 that summarizes the 

environmental impacts of transportation of fuel and waste to and from one LWR of 3000 to 

5000 MW(t) (1000 to 1500 MW(e)). Impacts are provided for normal conditions of transport and 

accidents in transport for a reference 1100-MW(e) LWR. The transportation impacts associated 

with the STP site were normalized for a reference 1100-MW(e) LWR at an 80 percent capacity 

factor for comparisons to Table S–4.(a) Dose to transportation workers during normal 

transportation operations was estimated to result in a collective dose of 4 person-rem per 

reference reactor year. The combined dose to the public along the route and dose to onlookers 

were estimated to result in a collective dose of 3 person-rem per reference reactor year. 

Environmental risks of radiological effects during accident conditions, as stated in Table S–4, 

are SMALL. Nonradiological impacts from postulated accidents were estimated as one fatal 

injury in 100 reactor years and one nonfatal injury in 10 reference reactor years. Subsequent 

reviews of transportation impacts in NUREG-0170 (NRC 1977a) and NUREG/CR-6672 (Sprung 

et al. 2000) concluded that impacts were bounded by Table S–4 in 10 CFR 51.52. 

 

(a) Note that the basis for Table S–4 is an 1100 MW(e) LWR at an 80% capacity factor (AEC 1972, NRC 

1975). The basis for Table S–3 in 10 CFR 51.51(b) that was discussed in Section 6.1 of this EIS is a 

1000 MW(e) LWR with an 80% capacity factor (NRC 1976). However, since fuel cycle and 

transportation impacts are evaluated separately, this difference does not affect the results and 

conclusions in this EIS. 
 Fuel Cycle, Transportation, and Decommissioning 

February 2011 6-17 NUREG-1937 

In accordance with 10 CFR 51.52(a), a full description and detailed analysis of transportation 

impacts is not required when licensing an LWR (i.e., impacts are assumed bounded by 

Table S–4) if the reactor meets the following criteria: 

• The reactor has a core thermal power level not exceeding 3800 MW(t). 

• Fuel is in the form of sintered uranium oxide pellets having a uranium-235 enrichment not 

exceeding 4 percent by weight; and pellets are encapsulated in zircalloy-clad fuel rods. 

• Average level of irradiation of the fuel from the reactor does not exceed 33,000 MWd/MTU, 

and no irradiated fuel assembly is shipped until at least 90 days after it is discharged from 

the reactor. 

• With the exception of irradiated fuel, all radioactive waste shipped from the reactor is 

packaged and in solid form. 

• Unirradiated fuel is shipped to the reactor by truck; irradiated (spent) fuel is shipped from the 

reactor by truck, rail, or barge; and radioactive waste other than irradiated fuel is shipped 

from the reactor by truck or rail. 

The environmental impacts of the transportation of fuel and radioactive wastes to and from 

nuclear power facilities were resolved generically in 10 CFR 51.52, provided that the specific 

conditions in the rule (see above) are met. The NRC may consider requests for licensed plants 

to operate at conditions above those in the facility's licensing basis; for example, higher burnups 

(above 33,000 MWd/MTU), enrichments (above 4 percent uranium-235), or thermal power 

levels (above 3800 MW(t)). Departures from the conditions itemized in 10 CFR 51.52(a) are to 

be supported by a full description and detailed analysis of the environmental effects, as 

specified in 10 CFR 51.52(b). Departures found to be acceptable for licensed facilities cannot 

serve as the basis for initial licensing for new reactors. 

In its application, STPNOC requested combined licenses (COLs) for two additional reactors at 

its STP site in Matagorda County, Texas. The proposed ABWR has a design thermal power 

rating of 4005 MW(t), with a net electrical output of approximately 1300 MW(e). The thermal 

power rating exceeds the 3800 MW(t) condition given in 10 CFR 51.52(a). The ABWR is 

expected to operate with a 95 percent capacity factor (STPNOC 2010a), resulting in a net 

electrical output (annualized) of about 1235 MW(e). Fuel for the plants would be enriched up to 

about 2.2 weight percent uranium-235 (U-235) for the initial core and 3.2 weight percent U-235 

for core reloads, both of which are less than the 10 CFR 51.52(a) condition. In addition, the 

average irradiation level of about 32,300 MWd/MTU (STPNOC 2010a) is also less than the 

10 CFR 51.52(a) condition. However, since the thermal power rating exceeds the 

10 CFR 51.52(a) condition, a full description and detailed analysis of transportation impacts is 

required. 
Fuel Cycle, Transportation, and Decommissioning 

NUREG-1937 6-18 February 2011 

In its ER (STPNOC 2010a), STPNOC provided a full description and detailed analyses of 

transportation impacts. In these analyses, the radiological impacts of transporting fuel and 

waste to and from the STP site and alternative sites were calculated using the RADTRAN 5.6 

computer code (Weiner et al. 2008). RADTRAN 5.6 was used in this EIS and is the most 

commonly used transportation impact analysis software in the nuclear industry. 

6.2.1 Transportation of Unirradiated Fuel

The NRC staff performed an independent evaluation of the environmental impacts of 

transporting unirradiated (i.e., fresh) fuel to the STP site and alternative sites. Radiological 

impacts of normal operating conditions and transportation accidents as well as nonradiological 

impacts are discussed in this section. Radiological impacts to populations and maximally 

exposed individuals (MEIs) are presented. Because the specific fuel fabrication plant for STP 

unirradiated fuel is not known at this time, the NRC staff’s analysis assumes a “representative” 

route between the fuel fabrication facility and STP site and alternative sites. This means that 

the route characteristics are identical for the STP site and alternative sites and there are no 

differences in impacts calculated between them in this EIS. However, site-specific differences 

would be small because the radiation doses from unirradiated fuel transport are minute and the 

differences in shipping distances between potential fuel fabrication plants and the STP site and 

alternative sites are small. 

6.2.1.1 Normal Conditions 

Normal conditions, sometimes referred to as “incident-free” transportation, are transportation 

activities during which shipments reach their destination without releasing any radioactive 

material to the environment. Impacts from these shipments would be from the low levels of 

radiation that penetrate the unirradiated fuel shipping containers. Radiation exposures at some 

level would occur to the following individuals: (1) persons residing along the transportation 

corridors between the fuel fabrication facility and the STP site; (2) persons in vehicles traveling 

on the same route as an unirradiated fuel shipment; (3) persons at vehicle stops for refueling, 

rest, and vehicle inspections; and (4) transportation crew workers. 

Truck Shipments 

Table 6-3 provides the NRC staff’s estimate of the number of truck shipments of unirradiated 

fuel for the ABWR compared to those of the reference 1100-MW(e) reactor specified in WASH1238 (AEC 1972) operating at 80-percent capacity (880 MW(e)). After normalization, the NRC 

staff found that the number of truck shipments of unirradiated fuel to the proposed STP site is 

slightly greater (about 5 percent) than the number of truck shipments of unirradiated fuel 

estimated for the reference LWR in WASH-1238. 
 Fuel Cycle, Transportation, and Decommissioning 

February 2011 6-19 NUREG-1937 

Table 6-3. Numbers of Truck Shipments of Unirradiated Fuel for the Reference LWR and the 

ABWR 

Reactor Type 

Number of Shipments 

per Reactor Unit Electric 

Generation, 

MW(e)(b) Capacity Factor(b)

Normalized, 

Shipments 

per 1100 

MW(e)(c) Total(a)

Reference LWR (WASH-1238) 252 1100 0.8 252 

STP ABWR 372 1300 0.95 265 

(a) Total shipments of unirradiated fuel over a 40-year plant lifetime (i.e., initial core load plus 39 years of average 

annual reload quantities). 

(b) Unit capacities and capacity factors were taken from WASH-1238 for the reference LWR and the ER 

(STPNOC 2010a) for the ABWR. 

(c) Normalized to net electric output for WASH-1238 reference LWR (i.e.,1100-MW(e) plant at 80 percent or net 

electrical output of 880 MW(e)). 

Shipping Mode and Weight Limits 

In 10 CFR 51.52, a condition is identified that states all unirradiated fuel is shipped to the 

reactor by truck. STPNOC specifies that unirradiated fuel would be shipped to the proposed 

reactor site by truck. Section 10 CFR 51.52, Table S–4, includes a condition that the truck 

shipments not exceed 73,000 lbs as governed by Federal or State gross vehicle weight 

restrictions. STPNOC states in its ER that the unirradiated fuel shipments to the proposed STP 

site would comply with applicable weight restrictions (STPNOC 2010a). 

Radiological Doses to Transport Workers and the Public 

Section 10 CFR 51.52, Table S–4, includes conditions related to radiological dose to transport 

workers and members of the public along transport routes. These doses are a function of many 

variables, including the radiation dose rate emitted from the unirradiated fuel shipments, the 

number of exposed individuals and their locations relative to the shipment, the time in transit 

(including travel and stop times), and number of shipments to which the individuals are 

exposed. For this EIS, the radiological dose impacts of the transportation of unirradiated fuel 

were calculated by the NRC staff for the worker and the public using the RADTRAN 5.6 

computer code (Weiner et al. 2008). 

One of the key assumptions in WASH-1238 (AEC 1972) for the reference LWR unirradiated fuel 

shipments is that the radiation dose rate at 3.3 ft from the transport vehicle is about 

0.1 mrem/hr, which is one percent of the regulatory limit. This assumption was also used in the 

NRC staff’s analysis of the ABWR unirradiated fuel shipments. This assumption is reasonable 

because the ABWR fuel materials would be low-dose-rate uranium radionuclides and would be 

packaged similarly to that described in WASH-1238 (i.e., inside a metal container that provides 

little radiation shielding). The numbers of shipments per year were obtained by dividing the 

normalized shipments in Table 6-3 by 40 years of reactor operation. Other key input 

parameters (listed in metric units) used in the radiation dose analysis for unirradiated fuel are 

shown in Table 6-4. 
Fuel Cycle, Transportation, and Decommissioning 

NUREG-1937 6-20 February 2011 

Table 6-4. RADTRAN 5.6 Input Parameters for Unirradiated Fuel Shipments 

Parameter

RADTRAN 5.6 

Input Value Source

Shipping distance, km 3200 AEC (1972)(a)

Travel Fraction – Rural 0.90 NRC (1977a) 

Travel Fraction – Suburban 0.05 

Travel Fraction – Urban 0.05 

Population Density – Rural, persons/km2

 10 DOE (2002a) 

Population Density – Suburban, persons/km2 349 

Population Density – Urban, persons/km2

 2260 

Vehicle speed – km/hr 88.49 Conservative in transit speed of 55 mph assumed; 

predominantly interstate highways used. 

Traffic count – Rural, vehicles/hr 530 DOE (2002a) 

Traffic count – Suburban, vehicles/hr 760 

Traffic count – Urban, vehicles/hr 2400 

Dose rate at 1 m from vehicle, mrem/hr 0.1 AEC (1972) 

Shipment length, m 8.94 Approximate length of two ABWR fuel assemblies 

placed end to end (INEEL 2003) 

Number of truck crew 2 AEC (1972), NRC (1977a), and DOE (2002a) 

Stop time, hr/trip 4 Based on 1 30-minute stop per 4 hr driving time 

(Johnson and Michelhaugh 2003) 

Population density at stops, persons/km2

 See Table 6-8 for truck stop parameters 

(a) AEC (1972) provides a range of shipping distances between 40 km (25 mi) and 4800 km (3000 mi) for 

unirradiated fuel shipments. A 3200-km (2000-mi) “representative” shipping distance was assumed here. 

The RADTRAN 5.6 results for this “generic” unirradiated fuel shipment are as follows: 

• Worker dose: 1.71 × 10-3 person-rem/shipment 

• General public dose (onlookers/persons at stops and sharing the highway): 

3.56 × 10-3 person-rem/shipment 

• General public dose (along route/persons living near a highway or truck stop): 5.04 × 10-5

person-rem/shipment. 

These values were combined with the average annual shipments of unirradiated fuel for the 

ABWR to calculate annual doses to the public and workers. Table 6-5 presents the annual 

radiological impacts calculated by the NRC staff to workers, public onlookers (persons at stops 

and sharing the road), and members of the public along the route (i.e., residents within 0.5 mi of 

the highway) for transporting unirradiated fuel to the STP site. The cumulative annual dose 

estimates in Table 6-5 were normalized to 1100 MW(e) [880 MW(e) net electrical output]. The 

NRC staff performed an independent review and determined that all dose estimates are 

bounded by the Table S–4 conditions of 4 person-rem/yr to transportation workers, 

3 person-rem/yr to onlookers, and 3 person-rem/yr to members of the public along the route. 
 Fuel Cycle, Transportation, and Decommissioning 

February 2011 6-21 NUREG-1937 

Table 6-5. Radiological Impacts Under Normal Conditions of Transporting Unirradiated Fuel to 

the STP Site or Alternative Sites

Plant Type 

Normalized 

Average 

Annual 

Shipments 

Cumulative Annual Dose; person-rem/yr per 

1100 MW(e)(a) (880 MW(e) net) 

Workers 

Public - 

Onlookers 

Public - 

Along Route 

Reference LWR (WASH-1238) 6.3 0.011 0.022 0.00032 

STP and Alternative Sites ABWR 6.6 0.011 0.024 0.00033 

10 CFR 51.52, Table S–4 Condition <1 per day 4 3 3 

(a) Multiply person-rem/yr times 0.01 to obtain doses in person-Sv/yr. 

Radiation protection experts assume that any amount of radiation may pose some risk of 

causing cancer or a severe hereditary effect and that the risk is higher for higher radiation 

exposures. Therefore, a linear, no-threshold dose response relationship is used to describe the 

relationship between radiation dose and detriments such as cancer induction. A recent report 

by the National Research Council (2006), the BEIR VII report, uses the linear, no-threshold 

dose response model as a basis for estimating the risks from low doses. This approach is 

accepted by the NRC as a conservative method for estimating health risks from radiation 

exposure, recognizing that the model may overestimate those risks. Based on this method, the 

NRC staff estimated the risk to the public from radiation exposure using the nominal probability 

coefficient for total detriment. This coefficient has the value of 570 fatal cancers, nonfatal 

cancers, and severe hereditary effects per 1,000,000 person-rem (10,000 person-Sv), equal to 

0.00057 effects per person-rem. The coefficient is taken from ICRP’s Publication 103 

(ICRP 2007). 

Both the NCRP and ICRP suggest that when the collective effective dose is smaller than the 

reciprocal of the relevant risk detriment (in other words, less than 1/0.00057, which is less than 

1754 person-rem), the risk assessment should note that the most likely number of excess health 

effects is zero (NCRP 1995; ICRP 2007). The largest annual collective dose estimate for 

transporting unirradiated fuel to the STP site and alternative sites was 2.4 × 10-2 person-rem, 

which is less than the 1754 person-rem value that ICRP and NCRP suggest would most likely 

result in zero excess health effects. 

To place these impacts in perspective, the average U.S. resident receives about 311 mrem/yr 

effective dose equivalent from natural background radiation (i.e., exposures from cosmic 

radiation, naturally occurring radioactive materials such as radon, and global fallout from testing 

of nuclear explosive devices) (NCRP 2009). Using this average effective dose, the collective 

population dose from natural background radiation to the population along this representative 

route would be about 2.2 x 105

 person-rem. Therefore, the radiation doses from transporting 
Fuel Cycle, Transportation, and Decommissioning 

NUREG-1937 6-22 February 2011 

unirradiated fuel to the STP site and alternative sites are minimal compared to the collective 

population dose to the same population from exposure to natural sources of radiation. 

Maximally Exposed Individuals Under Normal Transport Conditions 

A scenario-based analysis was conducted by the NRC staff to develop estimates of incidentfree radiation doses to MEIs for fuel and waste shipments to and from the STP site and 

alternative sites. The following discussion applies to unirradiated fuel shipments to, and spent 

fuel and radioactive waste shipments from, any of the alternative sites. The analysis is based 

on data in DOE (2002b) and incorporates data about exposure times, dose rates, and the 

number of times an individual may be exposed to an offsite shipment. Adjustments were made 

where necessary to reflect the normalized fuel and waste shipments addressed in this EIS. In 

all cases, the NRC staff assumed that the dose rate emitted from the shipping containers is 

10 mrem/hr at 2 m (6.6 ft) from the side of the transport vehicle. This assumption is 

conservative, in that the assumed dose rate is the maximum dose rate allowed by U.S. 

Department of Transportation (DOT) regulations (49 CFR 173.441). Most unirradiated fuel and 

radioactive waste shipments would have much lower dose rates than the regulations allow 

(AEC 1972; DOE 2002a). An MEI is a person who may receive the highest radiation dose from 

a shipment to and/or from the STP site and alternative sites. The analysis is described below. 

Truck crew member. Truck crew members would receive the highest radiation doses during 

incident-free transport because of their proximity to the loaded shipping container for an 

extended period. The analysis assumed that crew member doses are limited to 2 rem per year, 

which is the DOE administrative control level presented in DOE-STD-1098-99, DOE Standard, 

Radiological Control, Chapter 2, Article 211 (DOE 2005). The NRC staff anticipates this limit 

will apply to spent nuclear fuel shipments to a disposal facility, because DOE would take title to 

the spent fuel at the reactor site. There will be more shipments of spent nuclear fuel from the 

STP site (or alternative sites) than there will be shipments of unirradiated fuel to, and radioactive 

waste other than spent fuel from, these sites. This is because the capacities of spent fuel 

shipping casks are limited due to their substantial radiation shielding and accident resistance 

requirements. Spent fuel shipments also have significantly higher radiation dose rates than 

unirradiated fuel and radioactive waste (DOE 2002a). As a result, crew doses from unirradiated 

fuel and radioactive waste shipments would be lower than the doses from spent nuclear fuel 

shipments. The DOE administrative limit of 2 rem/yr (see DOE 2005) is less than the NRC limit 

for occupational exposures of 5 rem/yr (see 10 CFR Part 20). 

The U.S. DOT does not regulate annual occupational exposures. It does recognize that air 

crews are exposed to elevated cosmic radiation levels and recommends dose limits to air crew 

members from cosmic radiation (DOT 2003). Air passengers are less of a concern because 

they do not fly as frequently as air crew members. The recommended limits are a 5-year 

effective dose of 2 rem/yr with no more than 5 rem in a single year (DOT 2003). As a result of 
 Fuel Cycle, Transportation, and Decommissioning 

February 2011 6-23 NUREG-1937 

this recommendation, a 2 rem/yr MEI dose to truck crews is a reasonable estimate to apply to 

shipments of fuel and waste from the STP site and alternative sites. 

Inspectors. Radioactive shipments are inspected by Federal or State vehicle inspectors, for 

example, at State ports of entry. The Yucca Mountain Final EIS (DOE 2002b) assumed that 

inspectors would be exposed for 1 hour at a distance of 1 m (3.3 ft) from the shipping 

containers. Assuming conservatively that the external dose rate at 2 m (6.6 ft) is at the 

maximum allowed by regulations (10 mrem/hr), the dose rate at 1 m (3.3 ft) is about 14 mrem/hr 

(Weiner et al. 2008). Therefore, the dose per shipment is about 14 mrem. This is independent 

of the location of the reactor site. Based on this conservative external dose rate and the 

assumption that the same person inspects all shipments of fuel and waste to and from the STP 

site and alternative sites, the NRC staff calculated the annual doses to vehicle inspectors to be 

about 1.4 rem/yr, based on a combined total of 98 shipments of unirradiated fuel, spent fuel, 

and radioactive waste per year. This value is less than the DOE administrative control level 

(DOE 2005) on individual doses and is also less than the 5 rem/yr NRC occupational dose limit. 

Resident. The analysis assumed that a resident lives adjacent to a highway where a shipment 

would pass and would be exposed to all shipments along a particular route. Exposures to 

residents on a per-shipment basis were obtained from the NRC staff’s RADTRAN 5.6 output 

files. These dose estimates are based on an individual located 100 ft from the shipments that 

are traveling 15 mph. The potential radiation dose to the maximally exposed resident is about 

0.06 mrem/yr for shipments of fuel and waste to and from the STP site and alternative sites. 

Individual stuck in traffic. This scenario addresses potential traffic interruptions that could lead 

to a person being exposed to a loaded shipment for one hour at a distance of 4 ft. The NRC 

staff’s analysis assumed this exposure scenario would occur only one time to any individual, 

and the dose rate was at the regulatory limit of 10 mrem/hr at 2 m (6.6 ft) from the shipment, so 

the dose rate will be higher at the assumed exposure distance of 4 ft. The dose to the MEI was 

calculated to be 16 mrem in DOE’s Yucca Mountain Final EIS (DOE 2002b). 

Person at a truck service station. This scenario estimates doses to an employee at a service 

station where all truck shipments to and from the STP site and alternative sites are assumed to 

stop. The NRC staff’s analysis assumed this person would be exposed for 49 minutes at a 

distance of 52 ft from the loaded shipping container (DOE 2002b). The exposure time and 

distance were based on the observations discussed by Griego et al. (1996). This results in a 

dose of about 0.34 mrem/shipment and an annual dose of about 33 mrem/yr for the STP site 

and alternative sites, assuming that a single individual services all unirradiated fuel, spent fuel, 

and radioactive waste shipments to and from the STP site and alternative sites. 
Fuel Cycle, Transportation, and Decommissioning 

NUREG-1937 6-24 February 2011 

6.2.1.2 Radiological Impacts of Transportation Accidents 

Accident risks are a combination of accident frequency and consequence. Accident frequencies 

for transportation of unirradiated fuel to the STP site and alternative sites are expected to be 

lower than those used in the analysis in WASH-1238 (AEC 1972), which forms the basis for 

Table S–4 of 10 CFR 51.52, because of improvements in highway safety and security, and an 

overall reduction in traffic accident, injury, and fatality rates since WASH-1238 was published. 

There is no significant difference in consequences of transportation accidents severe enough to 

result in a release of unirradiated fuel particles to the environment between the ABWR and 

current-generation LWRs because the fuel form, cladding, and packaging are similar to those 

analyzed in WASH-1238. Consequently, consistent with the conclusions of WASH-1238 

(AEC 1972), the impacts of accidents during transport of unirradiated fuel for the ABWR at the 

STP site and alternative sites are expected to be negligible. 

6.2.1.3 Nonradiological Impacts of Transportation Accidents 

Nonradiological impacts are the human health impacts projected to result from traffic accidents 

involving shipments of unirradiated fuel to the STP site and alternative sites (that is, the analysis 

does not consider radiological or hazardous characteristics of the cargo). Nonradiological 

impacts include the projected number of traffic accidents, injuries, and fatalities that could result 

from shipments of unirradiated fuel to the site and return shipments of empty containers from 

the site. 

Nonradiological impacts are calculated using accident, injury, and fatality rates from published 

sources. The rates (i.e., impacts per vehicle-km traveled) are then multiplied by estimated 

travel distances for workers and materials. The general formula for calculating nonradiological 

impacts is: 

Impacts = (unit rate) × (round-trip shipping distance) × (annual number of shipments) 

In this formula, impacts are presented in units of the number of accidents, number of injuries, 

and number of fatalities per year. Corresponding unit rates (i.e., impacts per vehicle-km 

traveled) are used in the calculations. 

Accident, injury, and fatality rates were taken from Table 4 in ANL/ESD/TM-150 State-Level 

Accident Rates for Surface Freight Transportation: A Reexamination (Saricks and Tompkins 

1999). Nation-wide median rates were used for shipments of unirradiated fuel to the site. The 

data are representative of traffic accident, injury, and fatality rates for heavy truck shipments 

similar to those to be used to transport unirradiated fuel to the STP site and alternative sites. In 

addition, the U.S. Department of Transportation Federal Motor Carrier Safety Administration 

evaluated the data underlying the Saricks and Tompkins (1999) rates, which were taken from 

the Motor Carrier Management Information System, and determined that the rates were underreported. Therefore, the accident, injury, and fatality rates in Saricks and Tompkins (1999) were 
 Fuel Cycle, Transportation, and Decommissioning 

February 2011 6-25 NUREG-1937 

adjusted using factors derived from data provided by the University of Michigan Transportation 

Research Institute (UMTRI 2003). The UMTRI data indicate that accident rates for 1994 to 

1996, the same data used by Saricks and Tompkins (1999), were under-reported by about 

39 percent. Injury and fatality rates were under-reported by 16 and 36 percent, respectively. As 

a result, the accident, injury, and fatality rates were increased by factors of 1.64, 1.20, and 1.57, 

respectively, to account for the under-reporting. 

The nonradiological accident impacts calculated by the NRC staff for transporting unirradiated 

fuel to (and empty shipping containers from) the STP site and alternative sites are shown in 

Table 6-6. The nonradiological impacts associated with the WASH-1238 reference LWR are 

also shown for comparison purposes. Note that there are only small differences between the 

impacts calculated for an ABWR at the STP site and alternative sites and the reference LWR in 

WASH-1238 due entirely to the estimated annual number of shipments. Overall, the impacts 

are minimal and there are no substantive differences among the alternative sites. 

Table 6-6. Nonradiological Impacts of Transporting Unirradiated Fuel to the STP Site and 

Alternative Sites, Normalized to Reference LWR 

Plant Type 

Annual 

Shipments 

Normalized to 

Reference LWR 

One-Way 

Shipping 

Distance, 

km 

Round-trip 

Distance, 

km per 

Year 

Annual Impacts 

Accidents 

per Year 

Injuries 

per Year 

Fatalities 

per Year 

Reference LWR 

(WASH-1238) 

6.3 3200 4.0 × 104 1.9 × 10-2 9.3 × 10-3 5.8 × 10-4

STP and Alternative 

Sites ABWR 

6.6 3200 4.2 × 104 2.0 × 10-2 9.8 × 10-3 6.1 × 10-4

6.2.2 Transportation of Spent Fuel

The NRC staff performed an independent analysis of the environmental impacts of transporting 

spent fuel from the proposed STP site and alternative sites to a spent fuel disposal repository. 

For the purposes of these analyses, the NRC staff considered the proposed geologic HLW 

repository at the Yucca Mountain site in Nevada as a surrogate destination. Currently, NRC has 

not made a decision on the proposed geologic repository at Yucca Mountain. However, the 

NRC staff considers that an estimate of the impacts of the transportation of spent fuel to a 

possible repository in Nevada to be a reasonable bounding estimate of the transportation 

impacts to a storage or disposal facility because of the distances involved and the 

representativeness of the distribution of members of the public in urban, suburban, and rural 

areas (i.e., population distributions) along the shipping routes. Radiological and nonradiological 

environmental impacts of normal operating conditions and transportation accidents, as well as 

nonradiological impacts, are discussed in this section. 
Fuel Cycle, Transportation, and Decommissioning 

NUREG-1937 6-26 February 2011 

This NRC staff’s analysis is based on shipment of spent fuel by legal-weight trucks in shipping 

casks with characteristics similar to casks currently available (i.e., massive, heavily shielded, 

cylindrical metal pressure vessels). Due to the large size and weight of spent fuel shipping 

casks, each shipment is assumed to consist of a single shipping cask loaded on a modified 

trailer. These assumptions are consistent with those made in the evaluation of the 

environmental impacts of transportation of spent fuel in Addendum 1 to NUREG-1437 

(NRC 1999). Because the alternative transportation methods involve rail transportation or 

heavy-haul trucks, which would reduce the overall number of spent fuel shipments (NRC 1999), 

thereby reducing impacts, these assumptions are conservative. Also, the use of current 

shipping cask designs for this analysis results in conservative impact estimates because the 

current designs are based on transporting short-cooled spent fuel (approximately 120 days out 

of reactor). Future shipping casks would be designed to transport longer-cooled fuel (greater 

than 5 years out of reactor) and would require much less shielding to meet external dose 

limitations. Therefore, future shipping casks are expected to have higher cargo capacities, thus 

reducing the numbers of shipments and associated impacts. 

Radiological impacts of transportation of spent fuel were calculated by the NRC staff using the 

RADTRAN 5.6 computer code (Weiner et al. 2008). Routing and population data used in 

RADTRAN 5.6 for truck shipments were obtained from the Transportation Routing Analysis 

Geographic Information System (TRAGIS) routing code (Johnson and Michelhaugh 2003). The 

population data in the TRAGIS code are based on the 2000 census. Nonradiological impacts 

were calculated using published traffic accident, injury, and fatality data (Saricks and 

Tompkins 1999) in addition to route information from TRAGIS (Johnson and Michelhaugh 

2003). Traffic accident rates input to RADTRAN 5.6 and nonradiological impact calculations 

were adjusted to account for under-reporting, as discussed in Sections 4.8.3 and 6.2.1.3. 

6.2.2.1 Normal Conditions 

Normal conditions, sometimes referred to as “incident-free” conditions, are transportation 

activities in which shipments reach their destination without an accident occurring enroute. 

Impacts from these shipments would be from the low levels of radiation that penetrate the 

heavily shielded spent fuel shipping cask. Radiation exposures would occur to the following 

populations: (1) persons residing along the transportation corridors between the STP site and 

alternative sites and the proposed repository location; (2) persons in vehicles traveling on the 

same route as a spent fuel shipment; (3) persons at vehicle stops for refueling, rest, and vehicle 

inspections; and (4) transportation crew workers (drivers). For the purposes of this analysis, it 

was assumed that the destination for the spent fuel shipments is the proposed Yucca Mountain 

disposal facility in Nevada. This assumption is conservative because it tends to maximize the 

shipping distance from the STP site and alternative sites. 

Shipping casks have not been designed for the spent fuel from advanced reactor designs such 

as the ABWR. Information in Early Site Permit Environmental Report Sections and Supporting 
 Fuel Cycle, Transportation, and Decommissioning 

February 2011 6-27 NUREG-1937 

Documentation (INEEL 2003) indicated that advanced LWR fuel designs would not be 

significantly different from existing LWR designs; therefore, current shipping cask designs were 

used for the analysis of ABWR spent fuel shipments. The NRC staff assumed that the capacity 

of a truck shipment of ABWR spent fuel was 0.5 MTU/shipment, the same capacity as that used 

in WASH-1238 (AEC 1972). In its ER (STPNOC 2010a), STPNOC assumed a shipping cask 

capacity of 0.5 MTU/shipment. 

Input to RADTRAN 5.6 includes the total shipping distance between the origin and destination 

sites and the population distributions along the routes. This information was obtained by 

running the TRAGIS computer code (Johnson and Michelhaugh 2003) for highway routes from 

the proposed STP site and alternative sites to the proposed geologic HLW repository at Yucca 

Mountain. The resulting route characteristics information, generated by the NRC staff, is shown 

in Table 6-7. Note that for truck shipments, all the spent fuel is assumed to be shipped to the 

proposed Yucca Mountain site over designated highway-route controlled quantity routes. In 

addition, TRAGIS data were utilized in RADTRAN 5.6 on a state-by-state basis. This increases 

precision and could allow the results to be presented for each state along the route between the 

STP site and alternative sites and the proposed geologic HLW repository at Yucca Mountain, if 

desired. 

Radiation doses are a function of many parameters, including vehicle speed, traffic count, dose 

rate, packaging dimensions, number in the truck crew, stop time, and population density at 

stops. A listing of the values for these and other parameters that were used in the NRC staff’s 

analysis and the sources of the information is provided in Table 6-8. 

Table 6-7. Transportation Route Information for Shipments from the STP Site and Alternative 

Sites to the Proposed Geologic Repository at Yucca Mountain, Nevada(a) 

Advanced 

Reactor Site 

One-way Shipping Distance, km Population Density, persons/km2 Stop time 

per trip, 

Total Rural Suburban Urban Rural Suburban Urban hr 

STP Site 2922 2425 414 83 7.7 362.3 2437 3.5 

Allens Creek 2848 2356 409 83 7.7 358.2 2436 3.5 

Red 2 2604 2331 233 40 6.7 359.5 2272 3.0 

Trinity 2 2828 2435 319 73 7.2 372.3 2435 3.0 

Source: Johnson and Michelhaugh 2003 

(a) This table presents aggregated route characteristics provided by TRAGIS (Johnson and Michelhaugh 2003), 

including estimated distances from the alternative sites to the nearest TRAGIS highway node. Input to the 

RADTRAN 5.6 computer code was disaggregated to a state-by-state level. 
Fuel Cycle, Transportation, and Decommissioning 

NUREG-1937 6-28 February 2011 

Table 6-8. RADTRAN 5.6 Normal (Incident-free) Exposure Parameters 

Parameter 

RADTRAN 5.6 

Input Value Source 

Vehicle speed, km/hr 88.49 Based on average speed in rural areas given 

in DOE (2002a). Conservative in-transit speed 

of 55 mph assumed; predominantly interstate 

highways used. 

Traffic count – Rural, vehicles/hr State-specific Weiner et al. (2008) 

Traffic count – Suburban, vehicles/hr 

Traffic count – Urban, vehicles/hr 

Vehicle occupancy, persons/vehicle 1.5 DOE (2002a) 

Dose rate at 1 m from vehicle, mrem/hr 14 DOE (2002a, b) – approximate dose rate at 

1 m that is equivalent to maximum dose rate 

allowed by Federal regulations 

(i.e., 10 mrem/hr at 2 m from the side of a 

transport vehicle. 

Packaging dimensions, m Length – 5.2 

Diameter – 1.0

DOE (2002b) 

Number of truck crew 2 AEC (1972), NRC (1977a), and 

DOE (2002a, b) 

Stop time, hr/trip Route-specific See Table 6-5 

Population Density at Stops, 

persons/km2

30,000 Sprung et al. (2000). Equivalent to nine 

persons within 10 m of vehicle. See 

Figure 6-2. 

Min/Max Radii of Annular Area Around 

Vehicle at Stops, m 

1 to 10 Sprung et al. (2000) 

Shielding Factor Applied to Annular 

Area Surrounding Vehicle at Stops, 

dimensionless 

1 

(no shielding) 

Sprung et al. (2000) 

Population Density Surrounding Truck 

Stops, persons/km2

340 Sprung et al. (2000) 

Min/Max Radius of Annular Area 

Surrounding Truck Stop, m 

10 to 800 Sprung et al. (2000) 

Shielding Factor Applied to Annular 

Area Surrounding Truck Stop, 

dimensionless 

0.2 Sprung et al. (2000) 
 Fuel Cycle, Transportation, and Decommissioning 

February 2011 6-29 NUREG-1937 

For purposes of this analysis, the transportation crew for spent fuel shipments delivered by truck 

is assumed to consist of two drivers. Escort vehicles and drivers were considered, but they 

were not included because their distance from the shipping cask would reduce the dose rates to 

levels well below the dose rates experienced by the drivers and would be negligible. Stop times 

for refueling and rest were assumed to occur at the rate of 30 minutes per 4 hours driving time. 

TRAGIS outputs were used to estimate the number of stops. Doses to the public at truck stops 

have been significant contributors to the doses calculated in previous RADTRAN 5.6 analyses. 

For this analysis, doses to the public at refueling and rest stops (“stop doses”) are the sum of 

the doses to individuals located in two annular rings centered at the stopped vehicle, as 

illustrated in Figure 6-2. The inner ring represents persons who may be at the truck stop at the 

same time as a spent fuel shipment and extends 1 to 10 m from the edge of the vehicle. The 

outer ring represents persons who reside near a truck stop and extends from 10 to 800 m from 

the vehicle. This scheme is similar to that used in Sprung et al. (2000). Population densities 

and shielding factors were also taken from Sprung et al. (2000), which were based on the 

observations of Griego et al. (1996). 

Figure 6-2. Illustration of Truck Stop Model 
Fuel Cycle, Transportation, and Decommissioning 

NUREG-1937 6-30 February 2011 

The results calculated by the NRC staff for these normal (incident-free) exposure calculations 

are shown in Table 6-9 for the proposed STP site and alternative sites. Population dose 

estimates are given for workers (i.e., truck crew members), onlookers (doses to persons at 

stops and persons on highways exposed to the spent fuel shipment), and persons along the 

route (persons living near the highway). 

Table 6-9. Normal (Incident-Free) Radiation Doses to Transport Workers and the Public from 

Shipping Spent Fuel from the STP Site and Alternative Sites to the Proposed 

Geologic HLW Repository at Yucca Mountain 

Worker (Crew) Along Route Onlookers

Reference LWR (WASH-1238), person-rem/yr(a) 8.0 × 100 3.7 × 10-1 1.7 × 10+1

ABWR at STP Site, person-rem/yr 8.0 × 100 3.7 × 10-1 1.7 × 10+1

Allens Creek, person-rem/yr 7.8 × 100 3.6 × 10-1 1.7 × 10+1

Red 2, person-rem/yr 7.1 × 100 2.3 × 10-1 1.4 × 10+1

Trinity 2, person-rem/yr 7.7 × 100

 3.0 × 10-1 1.4 × 10+1

Table S–4 Condition, person-rem/yr 4 × 100

 3 × 100 3 × 100

(a) To convert person-rem to person-Sv, divide by 100. 

Shipping schedules for spent fuel generated by the proposed new unit have not been 

determined. It was determined by the NRC staff to be reasonable to calculate annual doses 

assuming the annual number of spent fuel shipments is equivalent to the annual refueling 

requirements. Population doses were normalized to the reference LWR in WASH-1238 

(880 net MW[e]). This corresponds to an 1100-MW(e) LWR operating at 80-percent capacity. 

The small differences in transportation impacts among the four alternative sites evaluated are 

not substantive. In general, the STP site has slightly higher impacts than the alternative sites, 

primarily because of the longer shipping distance to the proposed geologic HLW repository at 

Yucca Mountain. However, the differences among sites are relatively minor and are less than 

the uncertainty in the analytical results. 

The bounding cumulative doses to the exposed population given in Table S–4 are 

• 4 person-rem/reactor-year to transport workers 

• 3 person-rem/reactor-year to general public (onlookers) and members of the public along 

the route. 

The calculated population doses to the crew and onlookers for the reference LWR and the STP 

site and alternative site shipments exceed Table S–4 values. A key reason for the higher 

population doses relative to Table S–4 is the longer shipping distances assumed for this COL 

analysis (i.e., to a proposed repository in Nevada) than the distances used in WASH-1238. 
 Fuel Cycle, Transportation, and Decommissioning 

February 2011 6-31 NUREG-1937 

WASH-1238 assumed that each spent fuel shipment would travel a distance of 1000 mi, 

whereas the shipping distances used in this assessment were about 1600 to 1800 mi. If the 

shorter distance were used to calculate the impacts for the STP spent fuel shipments, the doses 

could be reduced by about 40 percent. Other important differences are the stop model 

described above and the additional precision that results from incorporating state-specific route 

characteristics and vehicle densities on highways (vehicles per hour). 

Where necessary, the NRC staff made conservative assumptions to calculate impacts 

associated with the transportation of spent fuel. Some of the key conservative assumptions are: 

• Use of the regulatory maximum dose rate (10 mrem/hr at 2 m) in the RADTRAN 5.6 

calculations. The shipping casks assumed in the EIS prepared by DOE in support of the 

application for a geologic repository at the proposed geologic HLW repository at Yucca 

Mountain (DOE 2002b) would transport spent fuel that has cooled for a minimum of 5 years 

(see 10 CFR 961, Subpart B). Most spent fuel would have cooled for much longer than 

5years before it is shipped to a possible geologic repository. Based on this, shipments from 

the STP site and alternative sites are also expected to be cooled for longer than 5 years. 

Consequently, the estimated population doses in Table 6-9 would be further reduced if more 

realistic dose rate projections and shipping cask capacities are used. 

• Use of 30 minutes as the average time at a truck stop in the calculations. Many stops made 

for actual spent fuel shipments are of short duration (i.e., 10 minutes) for brief visual 

inspections of the cargo (e.g., checking the cask tie-downs). These stops typically occur in 

minimally populated areas, such as an overpass or freeway ramp in an unpopulated area. 

Furthermore, empirical data provided in Griego et al. (1996) indicate that a 30-minute 

duration is toward the high end of the stop time distribution. Average stop times observed 

by Griego et al. (1996) are on the order of 18 minutes. More realistic stop times would 

further reduce the population doses in Table 6-9. 

A sensitivity study was performed by the NRC staff to demonstrate the effects of using more 

realistic dose rates and stop times on the incident-free population dose calculations. For this 

sensitivity study, the dose rate was reduced to 5 mrem/hr, the approximate 50 percent 

confidence interval of the dose rate distribution estimated by Sprung et al. (2000) for future 

spent fuel shipments. The stop time was reduced to 18 minutes per stop. All other RADTRAN 

5.6 input values were unchanged. The result is that the annual crew doses were reduced to 

2.8 person-rem/yr or about 36 percent of the annual dose shown in Table 6-9. The annual 

onlooker doses were reduced to 4.8 person-rem/yr (29 percent) and the annual doses to 

persons along the route were reduced to 0.13 person-rem/yr (37 percent). 

In its ER (STPNOC 2010a), STPNOC described the results of a RADTRAN 5.6 analysis of the 

impacts of incident-free transport of spent fuel to the proposed geologic HLW repository at 

Yucca Mountain. Although the overall approaches are the same (e.g., use of TRAGIS and 
Fuel Cycle, Transportation, and Decommissioning 

NUREG-1937 6-32 February 2011 

RADTRAN 5.6), there are some differences in the modeling details. For example, the NRC 

staff’s analysis used state-by-state route characteristics whereas STPNOC elected to use 

aggregated route information. The NRC staff concluded that the results produced by STPNOC 

are similar to those calculated by the NRC staff in this EIS. 

Using the linear no-threshold dose response relationship discussed in Section 6.2.1.1, the 

annual public dose impacts for transporting spent fuel from the STP or alternative sites to Yucca 

Mountain are about 20 person-rem, which is less than the 1754 person-rem value that ICRP 

(ICRP 2007) and NCRP (NCRP 1995) suggest would most likely result in no excess health 

effects. This dose is very small compared to the estimated 1.8 x 105

 person-rem that the same 

population along the route from the proposed STP site to the proposed geologic HLW repository 

at Yucca Mountain would incur annually from exposure to natural sources of radiation. Note 

that the estimated population dose along the STP-to-Yucca-Mountain route from natural 

background radiation is different than the natural background dose calculated by the NRC staff 

for unirradiated fuel shipments in Section 6.2.1.1 of this EIS because the route characteristics 

are different. A generic route was used in Section 6.2.1.1 for unirradiated fuel shipments and 

actual highway routes were used in this section for spent fuel shipments. 

Dose estimates to the MEI from transport of unirradiated fuel, spent fuel, and wastes under 

normal conditions are presented in Section 6.2.1.1. 

6.2.2.2 Radiological Impacts of Accidents 

As discussed previously, the NRC staff used the RADTRAN 5.6 computer code to estimate 

impacts of transportation accidents involving spent fuel shipments. RADTRAN 5.6 considers a 

spectrum of postulated transportation accidents, ranging from those with high frequencies and 

low consequences (e.g., “fender benders”) to those with low frequencies and high 

consequences (i.e., accidents in which the shipping container is exposed to severe mechanical 

and thermal conditions). 

Radionuclide inventories are important parameters in the calculation of accident risks. The 

radionuclide inventories used in this analysis were from the applicant’s ER (STPNOC 2010a). 

Spent fuel inventories used in the NRC staff analysis are presented in Table 6-10. The list of 

radionuclides set forth in the table includes all of the radionuclides that were included in the 

analysis conducted by Sprung et al. (2000). The analysis also included the inventory of crud, or 

radioactive material deposited on the external surfaces of LWR spent fuel rods. Because crud 

is deposited from corrosion products generated elsewhere in the reactor cooling system and the 

complete reactor design and operating parameters are uncertain, the quantities and 

characteristics of crud deposited on ABWR spent fuel are not available at this time. This 

uncertainty will be reduced over time as operating experience with advanced reactors 

increases; however, at the present time, only projections can be made using operating 

experience with the current generation of LWRs. For this EIS, the STP ABWR spent fuel 
 Fuel Cycle, Transportation, and Decommissioning 

February 2011 6-33 NUREG-1937 

transportation accident impacts were calculated by the NRC staff assuming the cobalt-60 

inventory in the form of crud is 169 Ci/MTU, based on information in Sprung et al. (2000). 

Table 6-10. Radionuclide Inventories Used in Transportation Accident Risk Calculations 

for an ABWR(a)

Radionuclide Ci/MTU 

Physical-Chemical 

Group 

Am-241 1440 Particulate 

Am-242m 33 Particulate 

Am-243 60 Particulate 

Ce-144 13,200 Particulate 

Cm-242 62 Particulate 

Cm-243 62 Particulate 

Cm-244 13,500 Particulate 

Cm-245 2 Particulate 

Co-60 (crud)(b) 169 Crud 

Co-60 (activation)(b) 3630 Particulate 

Cs-134 77,600 Cesium 

Cs-137 158,000 Cesium 

Eu-154 15,600 Particulate 

Eu-155 8270 Particulate 

Pm-147 31,300 Particulate 

Pu-238 10,900 Particulate 

Pu-239 427 Particulate 

Pu-240 852 Particulate 

Pu-241 135,000 Particulate 

Pu-242 3 Particulate 

Ru-106 22,900 Ruthenium 

Sb-125 7170 Particulate 

Sr-90 106,000 Particulate 

Y-90 106,000 Particulate 

(a) The source of the spent fuel inventories is STPNOC (2010a), 

Table 7.4-1, except as noted in footnote (b). 

(b) Co-60 exists both as an activation product in spent fuel and is 

the primary radioactive constituent in fuel assembly crud, or 

radioactive material deposited on the external surfaces of fuel 

assemblies. The Co-60 inventory in crud was calculated using 

information in NUREG/CR-6672 (Sprung et al. 2000).

Robust shipping casks are used to transport spent fuel because of the radiation shielding and 

accident resistance required by 10 CFR Part 71. Spent fuel shipping casks must be certified 

Type B packaging systems, meaning they must withstand a series of severe postulated accident 
Fuel Cycle, Transportation, and Decommissioning 

NUREG-1937 6-34 February 2011 

conditions with essentially no loss of containment or shielding capability. These casks are also 

designed with fissile material controls to ensure the spent fuel remains subcritical under normal 

and accident conditions. According to Sprung et al. (2000), the probability of encountering 

accident conditions that would lead to shipping cask failure is less than 0.01 percent (i.e., more 

than 99.99 percent of all accidents would result in no release of radioactive material from the 

shipping cask). The NRC staff assumed that shipping casks approved for transportation of 

spent fuel from an ABWR would provide equivalent mechanical and thermal protection of the 

spent fuel cargo. 

Accident frequencies are calculated in RADTRAN using user-specified accident rates and 

conditional shipping cask failure probabilities. State-specific accident rates were taken from 

Saricks and Tompkins (1999) and used in the RADTRAN calculations. The State-specific 

accident rates were then adjusted to account for under-reporting, as described in 

Section 6.2.1.3. Conditional shipping cask failure probabilities (i.e., the probability of cask 

failure as a function of the mechanical and thermal conditions applied in an accident) were 

taken from Sprung et al. (2000). 

The RADTRAN 5.6 accident risk calculations were performed using the radionuclide inventories 

given in Table 6-10. The resulting risk estimates were then multiplied by assumed annual spent 

fuel shipments to derive estimates of the annual accident risks associated with spent fuel 

shipments from the STP site and alternative sites to the proposed geologic HLW repository at 

Yucca Mountain in Nevada. As was done for routine exposures, the NRC staff assumed that 

the numbers of shipments of spent fuel per year are equivalent to the annual discharge 

quantities. 

For this assessment, release fractions for current-generation LWR fuel designs (Sprung et al. 

2000) were used to approximate the impacts from the ABWR spent fuel shipments. This 

assumes that the fuel materials and containment systems (i.e., cladding, fuel coatings) behave 

similarly to current LWR fuel under applied mechanical and thermal conditions. 

The NRC staff used RADTRAN 5.6 to calculate the population dose from the released 

radioactive material from four of five possible exposure pathways.(a) These pathways are: 

• External dose from exposure to the passing cloud of radioactive material (cloudshine). 

• External dose from the radionuclides deposited on the ground by the passing plume 

(groundshine). The NRC staff's analysis included the radiation exposure from this pathway 

even though the area surrounding a potential accidental release would be evacuated and 

decontaminated, thus preventing long-term exposures from this pathway. 

• Internal dose from inhalation of airborne radioactive contaminants (inhalation). 

 

(a) Internal dose from ingestion of contaminated food was not considered because the staff assumed 

evacuation and subsequent interdiction of foodstuffs following a postulated transportation accident. 
 Fuel Cycle, Transportation, and Decommissioning 

February 2011 6-35 NUREG-1937 

• Internal dose from resuspension of radioactive materials that were deposited on the ground 

(resuspension). The NRC staff's analysis included the radiation exposures from this 

pathway even though evacuation and decontamination of the area surrounding a potential 

accidental release would prevent long-term exposures. 

Table 6-11 presents the environmental consequences calculated by the NRC staff for 

transportation accidents when shipping spent fuel from the STP site and alternative sites to the 

proposed geologic HLW repository at Yucca Mountain. The shipping distances and population 

distribution information for the routes were the same as those used for the normal “incident-free” 

conditions (see Section 6.2.2.1). The results are normalized to the WASH-1238 reference 

reactor (880-MW(e) net electrical generation, 1100-MW(e) reactor operating at 80-percent 

capacity) to provide a common basis for comparison to the impacts listed in Table S–4. 

Although there are slight differences in impacts among the alternative sites, none of the 

alternative sites would be clearly favored over the STP site. 

Table 6-11. Annual Spent Fuel Transportation Accident Impacts for an ABWR at the STP Site 

and Alternative Sites, Normalized to Reference 1100-MW(e) LWR Net Electrical 

Generation 

 Normalized Population Impacts, Person-rem/RRY(a)

Reference LWR (WASH-1238) 1.5 × 10-4

ABWR at STP Site 1.5 × 10-4

Allens Creek 1.5 × 10-4

Red 2 5.8 × 10-5

Trinity 2 1.7 × 10-4

(a) Multiply person-Sv/yr times 100 to obtain person-rem/yr. 

Using the linear no-threshold dose response relationship discussed in Section 6.2.1.1, the 

annual collective public dose estimates for transporting spent fuel from the STP and 

alternative sites to the proposed geologic repository at Yucca Mountain are on the order of 

1 × 10-4 person-rem, which is less than the 1754 person-rem value that ICRP (ICRP 2007) and 

NCRP (NCRP 1995) suggest would most likely result in zero excess health effects. This risk is 

very minute compared to the estimated 1.8 x 105

 person-rem that the same population would 

receive annually along the route from the proposed STP site to the proposed geologic HLW 

repository at Yucca Mountain from exposure to natural sources of radiation. 

6.2.2.3 Nonradiological Impact of Spent Fuel Shipments 

The general approach used to calculate nonradiological impacts of spent fuel shipments is the 

same as that used for unirradiated fuel shipments. The main difference is that the spent fuel 

shipping route characteristics are better-defined so the State-level accident statistics in Saricks 
Fuel Cycle, Transportation, and Decommissioning 

NUREG-1937 6-36 February 2011 

and Tompkins (1999) may be used. State-by-State shipping distances were obtained from the 

TRAGIS output file and combined with the annual number of shipments and accident, injury, 

and fatality rates by State from Saricks and Tompkins (1999) to calculate nonradiological 

impacts. In addition, the accident, injury, and fatality rates from Saricks and Tompkins (1999) 

were adjusted to account for under-reporting (see Section 6.2.1.3). The results calculated by 

the NRC staff are shown in Table 6-12. Overall, the impacts are minimal and there are no 

substantive differences among the alternative sites. 

Table 6-12. Nonradiological Impacts of Transporting Spent Fuel from the STP Site and 

Alternative Sites to the Proposed Geologic HLW Repository at Yucca Mountain, 

Nevada, Normalized to Reference LWR 

Site 

One-Way Shipping 

Distance, km 

Nonradiological Impacts, per Year 

Accidents/yr Injuries/yr Fatalities/yr 

STP (proposed site) 2922 2.0 × 10-1 1.3 × 10-1 6.2 × 10-3

Allens Creek 2848 1.9 × 10-1 1.2 × 10-1 5.7 × 10-3

Red 2 2604 1.2 × 10-1

 7.9 × 10-2 5.5 × 10-3

Trinity 2 2828 1.5 × 10-1

 9.6 × 10-2 6.2 × 10-3

Note: The number of shipments of spent fuel assumed in the calculations is 60 shipments/yr after normalizing to the 

reference LWR. 

6.2.3 Transportation of Radioactive Waste 

This section discusses the environmental effects of transporting radioactive waste other than 

spent fuel from the STP site and alternative sites. The environmental conditions listed in 

10 CFR 51.52 that apply to shipments of radioactive waste are as follows: 

• Radioactive waste (except spent fuel) would be packaged and in solid form. 

• Radioactive waste (except spent fuel) would be shipped from the reactor by truck or rail. 

• The weight limitation of 73,000 lb per truck and 100 tons per cask per railcar would be met. 

• Traffic density would be less than the one truck shipment per day or three railcars per month 

condition. 

Radioactive waste other than spent fuel from the STP ABWR is expected to be capable of being 

shipped in compliance with Federal and/or State weight restrictions. Table 6-13 presents the 

NRC staff’s estimates of annual waste volumes and annual waste shipment numbers for an 

ABWR normalized to the reference 1100-MW(e) LWR defined in WASH-1238 (AEC 1972). The 

expected annual waste volumes for the ABWR are estimated at 3500 ft3

/yr, and the annual 

number of waste shipments was estimated at 31 shipments per year after normalization to the 

reference LWR in WASH-1238. The annual waste volume and annual number of shipments are 

less than those for the 1100-MW(e) reference reactor that was the basis for Table S–4. The 

annual shipment estimates could also be reduced if more efficient packagings are used to 

transport waste from STP than were assumed in WASH-1238. 
 Fuel Cycle, Transportation, and Decommissioning 

February 2011 6-37 NUREG-1937 

Table 6-13. Summary of Radioactive Waste Shipments from the STP Site and Alternative Sites

Reactor Type 

Waste 

Generation 

Information 

Annual Waste 

Volume, 

m3/yr per Unit

Electrical 

Output, 

MW(e) per 

Unit 

Normalized 

Rate, m3

/1100 

MW(e) Unit (880 

MW(e) Net)(a)

Shipments/ 

1100 MW(e) 

(880 MW(e) Net) 

Electrical 

Output(b)

Reference LWR 

(WASH-1238) 

3800 ft3/yr 

per unit 

108 1100 108 46 

STP ABWR 

(ER volume) 

3500 ft3/yr 

per unit(c)

99(c) 1300(c)

 71 31 

Conversions: 1 m3 = 35.31 ft3. Drum volume = 210 liters (0.21 m3). 

(a) Capacity factors used to normalize the waste generation rates to an equivalent electrical generation output are 

80 percent for the reference LWR (AEC 1972) and 95 percent for the STP ABWR (STPNOC 2010a). Waste 

generation for the ABWR is normalized to 880 MW(e) net electrical output (1100-MW(e) unit with an 80-percent 

capacity factor). 

(b) The number of shipments per 1100 MW(e) was calculated by dividing the normalized rate by the assumed 

shipment capacity used in WASH-1238 (2.34 m3

/shipment). 

(c) This value was taken from the ER (STPNOC 2010a). 

The sum of the daily shipments of unirradiated fuel, spent fuel, and radioactive waste for an 

ABWR located at the STP site and alternative sites is less than the one-truck-shipment-per-day 

condition given in 10 CFR 51.52, Table S–4. 

Dose estimates to the MEI from transport of unirradiated fuel, spent fuel, and waste under 

normal conditions are presented in Section 6.2.1.1. 

Nonradiological impacts of radioactive waste shipments were calculated using the same general 

approach as unirradiated and spent fuel shipments. For this EIS, the shipping distance was 

assumed to be 500 mi one way (AEC 1972). Because the actual destination is uncertain, 

national median accident, injury, and fatality rates were used in the calculations (Saricks and 

Tompkins 1999). These rates were adjusted to account for under-reporting, as described in 

Section 6.2.1.3. The results calculated by the NRC staff are presented in Table 6-14. As 

shown, the calculated nonradiological impacts for transportation of radioactive waste other than 

spent fuel from the STP site and alternative sites to waste disposal facilities are less than the 

impacts calculated for the reference LWR in WASH-1238. 
Fuel Cycle, Transportation, and Decommissioning 

NUREG-1937 6-38 February 2011 

Table 6-14. Nonradiological Impacts of Radioactive Waste Shipments from the STP Site 

Normalized 

Shipments 

per Year 

One-Way 

Distance, 

km 

Accidents 

per Year 

Injuries 

per Year 

Fatalities 

per Year 

Reference LWR (WASH-1238) 46 800 3.4 × 10-2 1.7 × 10-2 1.1 × 10-3

STP ABWR 31 800 2.3 × 10-2 1.1 × 10-2 7.2 × 10-4

Note: The shipments and impacts have been normalized to the reference LWR. 

6.2.4 Conclusions

The NRC staff conducted confirmatory analyses and performed independent calculations of 

potential impacts under normal operating and accident conditions of transportation of fuel and 

wastes to and from an ABWR to be located at the proposed STP site and alternative sites. To 

make comparisons to Table S–4, the environmental impacts were adjusted (that is, normalized) 

to the environmental impacts associated with the reference LWR in WASH-1238 (AEC 1972) by 

multiplying the ABWR impact estimates by the ratio of the total electric output for the reference 

reactor to the electric output of the proposed reactor. 

Because of the conservative approaches and data used to calculate impacts, the NRC staff 

does not expect that actual environmental effects will exceed those calculated in this EIS. Thus, 

the NRC staff concludes that the environmental impacts of transportation of fuel and radioactive 

wastes to and from the STP site and alternative sites site would be SMALL, and would be 

consistent with the environmental impacts associated with transportation of fuel and radioactive 

wastes to and from current-generation reactors presented in Table S–4 of 10 CFR 51.52. 

The NRC staff notes that on March 3, 2010, DOE (DOE 2010) submitted a motion to the Atomic 

Safety and Licensing Board to withdraw with prejudice its application for a permanent geologic 

repository at Yucca Mountain, Nevada. Regardless of the outcome of this motion, the NRC staff 

concludes that transportation impacts are roughly proportional to the distance from the reactor 

site to the repository site, in this case Texas to Nevada. The distance from the STP site or any 

of the alternate sites to any new planned repository in the contiguous United States would be no 

more than double the distance from the STP site to Yucca Mountain. Doubling the 

environmental impact estimates from the transportation of spent reactor fuel, as presented in 

this Section, would provide a reasonable bounding estimate of the impacts for NEPA purposes. 

The NRC staff concludes that the environmental impacts of these doubled estimates would still 

be SMALL. 
 Fuel Cycle, Transportation, and Decommissioning 

February 2011 6-39 NUREG-1937 

6.3 Decommissioning Impacts 

At the end of the operating life of a nuclear power reactor, NRC regulations require that the 

facility be decommissioned. The NRC defines decommissioning as the safe removal of a facility 

from service and the reduction of residual radioactivity to a level permitting termination of the 

NRC license. Sections 10 CFR 50.75 and 50.82 provide the NRC regulations governing 

decommissioning power reactors. The radiological criteria for termination of the NRC license 

are in 10 CFR Part 20, Subpart E. 

An applicant for a COL is required to certify that sufficient funds will be available to assure 

radiological decommissioning at the end of power operations. As part of its COL application for 

the proposed Units 3 and 4 on the STP site, STPNOC included a Decommissioning Funding 

Assurance Report (STPNOC 2010b). STPNOC would establish an external sinking funds 

account to accumulate funds for decommissioning. 

Environmental impacts from the activities associated with the decommissioning of any reactor 

before or at the end of an initial or renewed license are evaluated in the Generic Environmental 

Impact Statement on Decommissioning of Nuclear Facilities: Supplement I, Regarding the 

Decommissioning of Nuclear Power Reactors (GEIS-DECOM), NUREG-0586 Supplement 1 

(NRC 2002). Environmental impacts of the DECON, SAFSTOR, and ENTOMB 

decommissioning methods are evaluated in the GEIS-DECOM. A COL applicant is not required 

to identify a decommissioning method at the time of the COL application. The NRC staff’s 

evaluation of the environmental impacts of decommissioning presented in the GEIS-DECOM, 

identifies a range of impacts for each environmental issue for a range of different reactor 

designs. The NRC staff concludes that the construction methods that would be used for the 

ABWR are not sufficiently different from the construction methods used for the current plants to 

significantly affect the impacts evaluated in the GEIS-DECOM. Therefore, the NRC staff 

concludes that the impacts discussed in the GEIS-DECOM remain bounding for reactors 

deployed after 2002, including the ABWR. 

The GEIS-DECOM does not specifically address the carbon footprint of decommissioning 

activities. However, it does list the decommissioning activities and states that the 

decommissioning workforce would be expected to be smaller than the operational workforce 

and that the decontamination and demolition activities could take up to 10 years to complete. 

Finally, it discusses SAFSTOR, in which decontamination and dismantlement are delayed for a 

number of years. Given this information, the NRC staff estimated the CO2 footprint of 

decommissioning to be of the order of 70,000 metric tons without SAFSTOR. This footprint is 

about equally split between decommissioning workforce transportation and equipment usage. 

The details of the NRC staff’s estimate are presented in Appendix I. A 40-yr SAFSTOR period 
Fuel Cycle, Transportation, and Decommissioning 

NUREG-1937 6-40 February 2011 

would increase the footprint of decommissioning by about 40 percent. These CO2 footprints are 

roughly three orders of magnitude lower than the CO2 footprint presented in Section 6.1.3 for 

the uranium fuel cycle. 

The NRC staff relies upon the bases established in the GEIS-DECOM and concludes the 

following: 

1. Doses to the public would be well below applicable regulatory standards regardless of which 

decommissioning method considered in GEIS-DECOM is used. 

2. Occupational doses would be well below applicable regulatory standards during the license 

term. 

3. The quantities of Class C or greater than Class C wastes generated would be comparable 

or less than the amounts of solid waste generated by reactors licensed before 2002. 

4. Air quality impacts of decommissioning are expected to be negligible at the end of the 

operating term. 

5. Measures are readily available to avoid potential significant water quality impacts from 

erosion or spills. The liquid radioactive waste system design includes features to limit 

release of radioactive material to the environment, such as pipe chases and tank collection 

basins. These features will minimize the amount of radioactive material in spills and leakage 

that would have to be addressed at decommissioning. 

6. Ecological impacts of decommissioning are expected to be negligible. 

7. Socioeconomic impacts would be short-term and could be offset by decreases in population 

and economic diversification. 

On the basis of the GEIS-DECOM and the evaluation of air quality impacts from greenhouse 

gas emissions above, the NRC staff concludes that, as long as the regulatory requirements on 

decommissioning activities to limit the impacts of decommissioning are met, the 

decommissioning activities would result in a SMALL impact. 

6.4 References 

10 CFR Part 20. Code of Federal Regulations, Title 10, Energy, Part 20, “Standards for 

Protection Against Radiation.” 

10 CFR Part 50. Code of Federal Regulations, Title 10, Energy, Part 50, “Domestic Licensing of 

Production and Utilization Facilities.” 

10 CFR Part 51. Code of Federal Regulations, Title 10, Energy, Part 51, “Environmental 

Protection Regulations for Domestic Licensing and Related Regulatory Functions.” 
 Fuel Cycle, Transportation, and Decommissioning 

February 2011 6-41 NUREG-1937 

10 CFR Part 71. Code of Federal Regulations, Title 10, Energy, Part 71, “Packaging and 

Transportation of Radioactive Material.” 

10 CFR Part 961. Code of Federal Regulations, Title 10, Energy. Part 961, “Standard Contract 

for Disposal of Spent Nuclear Fuel and/or High Level Waste.” 

40 CFR Part 190. Code of Federal Regulations, Title 40, Protection of Environment, Part 190, 

“Environmental Radiation Protection Standards for Nuclear Power Operations.” 

49 CFR Part 173. Code of Federal Regulations, Title 49, Protection of Environment, Part 173, 

"Shippers-General Requirements for Shipments and Packagings." 

61 FR 65120. December 10, 1996. "Resolution of Dual Regulation of Airborne Effluents of 

Radioactive Materials; Clean Air Act." Federal Register. U.S. Nuclear Regulatory Commission. 

73 FR 59551. October 9, 2008. “Waste Confidence Decision Update.” Federal Register. U.S. 

Nuclear Regulatory Commission. 

73 FR 72370. November 28, 2008. “Consideration of Environmental Impacts of Temporary 

Storage of Spent Fuel After Cessation of Reactor Operation and Waste Confidence Decision 

Update: Extension of Comment Period.” Federal Register. U.S. Nuclear Regulatory 

Commission. 

75 FR 81032. December 23, 2010. “10 CFR Part 51 Consideration of Environmental Impacts 

of Temporary Storage of Spent Fuel After Cessation of Reactor Operation; Waste Confidence 

Decision Update; Final Rules.” Federal Register. U.S. Nuclear Regulatory Commission. 

Baltimore Gas & Electric Co. v. Natural Resources Defense Council, Inc. 1983. United States 

Reports, Vol 460, p. 1034. 

Energy Policy Act of 2005. 45 USC 15801, et seq. 

Griego, N.R., J.D. Smith, and K.S. Neuhauser. 1996. “Investigation of RADTRAN Stop Model 

Input Parameters for Truck Stops.” Conference Proceedings - Waste Management 96, CONF960212-44, Tucson, Arizona. 

International Commission on Radiological Protection (ICRP). 2007. “Recommendations of the 

ICRP.” ICRP Publication No. 103. Ann ICRP 37(2-4). 

Idaho National Engineering and Environmental Laboratory (INEEL). 2003. Early Site Permit 

Environmental Report Sections and Supporting Documentation. Engineering Design File 

Number 3747, Idaho Falls, Idaho. 
Fuel Cycle, Transportation, and Decommissioning 

NUREG-1937 6-42 February 2011 

Johnson, P.E. and R.D. Michelhaugh. 2003. Transportation Routing Analysis Geographic 

Information System (TRAGIS) User’s Manual. ORNL/TM-2000/86, Oak Ridge National 

Laboratory, Oak Ridge, Tennessee. 

National Cancer Institute (NCI). 1990. Cancer in Populations Living Near Facilities. National 

Institutes of Health, Washington, D.C. 

National Council on Radiation Protection and Measurements (NCRP). 1995. Principles and 

Application of Collective Dose in Radiation Protection. Report No. 121, NCRP Publications, 

Bethesda, Maryland. 

National Council on Radiation Protection and Measurements (NCRP). 2009. Ionizing Radiation 

Exposure of the Population of the United States. NCRP Report No. 160, Bethesda, Maryland. 

National Research Council. 2006. Health Risks for Exposure to Low Levels of Ionizing 

Radiation: BEIR VII - Phase 2. National Research Council of the National Academies, National 

Academies Press, Washington, D.C. 

Nuclear Non-Proliferation Act of 1978, as amended. 22 USC 3201, et seq. 

Nuclear Waste Policy Act of 1982, as amended. 42 USC 10101, et seq. 

Saricks, C.L. and M.M. Tompkins. 1999. State-Level Accident Rates for Surface Freight 

Transportation: A Reexamination. ANL/ESD/TM-150, Argonne National Laboratory, Argonne, 

Illinois. 

South Texas Project Nuclear Operating Company (STPNOC). 2010a. South Texas Project 

Units 3 and 4 Combined License Application, Part 3, Environmental Report. Revision 4, Bay 

City, Texas. Accession No. ML102860592. 

South Texas Project Nuclear Operating Company (STPNOC). 2010b. South Texas Project 

Units 3 and 4 Combined License Application, Part 1, General and Financial Information. 

Revision 4, Bay City, Texas. Accession No. ML102860173. 

Sprung, J.L., D.J. Ammerman, N.L. Breivik, R.J. Dukart, F.L. Kanipe, J.A. Koski, G.S. Mills, 

K.S. Neuhauser, H.D. Radloff, R.F. Weiner, and H.R. Yoshimura. 2000. Reexamination of 

Spent Fuel Shipment Risk Estimates. NUREG/CR-6672, NRC, Washington, D.C. 

Texas Commission on Environmental Quality (TCEQ). 2009. Radioactive Material License. 

License no. R04100. Austin, Texas. Accession No. ML100630472. 
 Fuel Cycle, Transportation, and Decommissioning 

February 2011 6-43 NUREG-1937 

University of Michigan Transportation Research Institute (UMTRI). 2003. Evaluation of the 

Motor Carrier Management Information System Crash File, Phase One. UMTRI 2003-6. Ann 

Arbor, Michigan. 

U.S. Atomic Energy Commission (AEC). 1972. Environmental Survey of Transportation of 

Radioactive Materials to and from Nuclear Power Plants. WASH-1238, Washington, D.C. 

U.S. Atomic Energy Commission (AEC). 1974. Environmental Survey of the Uranium Fuel 

Cycle. WASH-1248, Washington, D.C. 

U.S. Department of Energy (DOE). 2002a. A Resource Handbook on DOE Transportation Risk 

Assessment. DOE/EM/NTP/HB-01, Washington, D.C. 

U.S. Department of Energy (DOE). 2002b. Final Environmental Impact Statement for a 

Geologic Repository for the Disposal of Spent Nuclear Fuel and High-Level Radioactive Waste 

at Yucca Mountain, Nye County, Nevada. DOE/EIS-0250, Office of Civilian Radioactive Waste 

Management, Washington, D.C. 

U.S. Department of Energy (DOE). 2005. DOE Standard Radiation Control. DOE-STD-1098-

99, Washington, D.C. 

U.S. Department of Energy (DOE). 2009. Electric Power Monthly. August 2009, DOE/EIA0226, Energy Information Administration, Office of Coal, Nuclear, Electric and Alternate Fuels, 

Washington, DC. 

U.S. Department of Energy (DOE). 2010. March 03, 2010. U.S. Department of Energy’s 

Motion to Withdraw. Docket No. 63-001. Accession No. ML100621397. 

U.S. Department of Transportation (DOT). 2003. What Aircrews Should Know About Their 

Occupational Exposure to Ionizing Radiation. DOT/FAA/AM-3/16, Federal Aviation 

Administration, Washington, D.C. 

U.S. Environmental Protection Agency (EPA). 2010. Inventory of U.S. Greenhouse Gas 

Emissions and Sinks: 1990-2008, U.S. EPA # 430-R-10-006, Washington, D.C. 

U.S. Nuclear Regulatory Commission (NRC). 1975. Environmental Survey of Transportation of 

Radioactive Materials to and from Nuclear Power Plants, Supplement 1. NUREG-75/038, 

WASH-1238, Washington, D.C. 

U.S. Nuclear Regulatory Commission (NRC). 1976. Environmental Survey of the Reprocessing 

and Waste Management Portions of the LWR Fuel Cycle. NUREG-0116 (Supplement 1 to 

WASH-1248), Washington, D.C. 
Fuel Cycle, Transportation, and Decommissioning 

NUREG-1937 6-44 February 2011 

U.S. Nuclear Regulatory Commission (NRC). 1977a. Final Environmental Statement on 

Transportation of Radioactive Material by Air and Other Modes. NUREG-0170, Vol.1, 

Washington, D.C. 

U.S. Nuclear Regulatory Commission (NRC). 1977b. Public Comments and Task Force 

Responses Regarding the Environmental Survey of the Reprocessing and Waste Management 

Portions of the LWR Fuel Cycle. NUREG-0216 (Supplement 2 to WASH-1248), Washington, 

D.C. 

U.S. Nuclear Regulatory Commission (NRC). 1996. Generic Environmental Impact Statement 

for License Renewal of Nuclear Plants. NUREG-1437, Vols. 1 and 2, Washington, D.C. 

U.S. Nuclear Regulatory Commission (NRC). 1999. Generic Environmental Impact Statement 

for License Renewal of Nuclear Plants, Main Report,“ Section 6.3 – Transportation, Table 9.1, 

Summary of findings on NEPA issues for license renewal of nuclear power plants, Final Report.” 

NUREG-1437, Vol. 1, Addendum 1, Washington, D.C. 

U.S. Nuclear Regulatory Commission (NRC). 2002. Generic Environmental Impact Statement 

on Decommissioning of Nuclear Facilities, Supplement 1, Regarding the Decommissioning of 

Nuclear Power Reactors. NUREG-0586, Supplement 1, Vols. 1 and 2, Washington, D.C. 

U. S. Nuclear Regulatory Commission (NRC). 2008. NRC Regulatory Issue Summary 2008-12 

– Considerations for Extended Interim Storage of Low-Level Radioactive Waste by Fuel Cycle 

and Materials Licensees. May 9, 2008. Accession No. ML073330725. 

The UxC Consulting Company, LLC. (UxC). 2009. UxC Nuclear Fuel Price Indicators; Spot 

Price of Uranium. Accessed May 15, 2009 at http://www.uxc.com/review/uxc_Prices.aspx. 

Valhi, Inc. (Valhi). 2011. Valhi, Inc. Announces WCS Start of Construction of Disposal Facility. 

Accessed January 12, 2011 at http://www.valhi.net/phoenix.zhtml?c=103380&p=irolnewsArticle&ID=1511914&highlight=. 

Weiner, R.F., D.M. Osborn, G.S. Mills, D. Hinojosa, T.L. Heames, and D.J. Orcutt. 2008. 

RadCat 2.3 User Guide. SAND2006-6315, Sandia National Laboratories, Albuquerque, New 

Mexico. 
February 2011 7-1 NUREG-1937 

7.0 Cumulative Impacts 

The National Environmental Policy Act of 1969, as amended (NEPA), requires Federal agencies 

to consider the cumulative impacts of proposals under its review. Cumulative impacts may 

result when the environmental effects associated with the proposed action are overlaid or added 

to temporary or permanent effects associated with past, present, and reasonably foreseeable 

future projects. Cumulative impacts can result from individually minor, but collectively significant 

actions taking place over a period of time. When evaluating the potential impacts of 

construction and operation of two new nuclear units at the South Texas Project Electric 

Generating Station (STP) site proposed by STP Nuclear Operating Company (STPNOC) in its 

application for combined licenses (COLs) which included an Environmental Report (ER) 

(STPNOC 2010a), the U.S. Nuclear Regulatory Commission (NRC) and the U.S. Army Corps of 

Engineers (Corps) review team considered potential cumulative impacts to resources that could 

be affected by the construction, preconstruction, and operation of two U.S. Advanced Boiling 

Water Reactors (ABWRs) at the STP site. Cumulative impacts result when the effects of an 

action are added to or interact with other past, present, and reasonably foreseeable future 

effects on the same resources. For purposes of this analysis, past actions are those prior to the 

receipt of the COL application. Present actions are those related to resources from the time of 

the COL application until the start of NRC-authorized construction of the proposed new units. 

Future actions are those that are reasonably foreseeable through building and operating the 

proposed Units 3 and 4, including decommissioning. The geographic area over which past, 

present, and reasonably foreseeable future actions could contribute to cumulative impacts is 

dependent on the type of resource considered and is described below for each resource area. 

The review team considered, among other things, cumulative effects of the proposed Units 3 

and 4 with current operations at existing STP Units 1 and 2. 

The approach for this environmental impact statement (EIS) is outlined in the following 

discussion. To guide its assessment of environmental impacts of a proposed action or 

alternative actions, the NRC has established a standard of significance for impacts based on 

guidance developed by the Council on Environmental Quality (CEQ) (40 Code of Federal 

Regulations [CFR] 1508.27). The three significance levels established by the NRC – SMALL, 

MODERATE, or LARGE – are defined as follows: 

SMALL – Environmental effects are not detectable or are so minor that they will neither 

destabilize nor noticeably alter any important attribute of the resource. 

MODERATE – Environmental effects are sufficient to alter noticeably, but not to 

destabilize, important attributes of the resource. 

LARGE – Environmental effects are clearly noticeable and are sufficient to destabilize 

important attributes of the resource. 
Cumulative Impacts 

NUREG-1937 7-2 February 2011 

The impacts of the proposed action, as described in Chapters 4 and 5, are combined with other 

past, present, and reasonably foreseeable future actions in the general area surrounding the 

STP site that would affect the same resources impacted by the proposed new units, regardless 

of what agency (Federal or non-Federal) or person undertakes such actions. These combined 

impacts are defined as “cumulative” in 40 CFR 1508.7 and include individually minor but 

collectively potentially significant actions taking place over a period of time. It is possible that an 

impact that may be SMALL by itself could result in a MODERATE or LARGE cumulative impact 

when considered in combination with the impacts of other actions on the affected resource. 

Likewise, if a resource is regionally declining or imperiled, even a SMALL individual impact 

could be important if it contributes to or accelerates the overall resource decline. 

The description of the affected environment in Chapter 2 serves as the baseline for the 

cumulative impacts analysis, including the effects of past actions. The incremental impacts 

related to the construction activities requiring NRC authorization (10 CFR 50.10(a)) are 

described and characterized in Chapter 4 and those related to operations are described and 

characterized in Chapter 5. These impacts are summarized for each resource area in the 

sections that follow. The level of detail is commensurate with the significance of the impact for 

each resource area. 

This chapter includes an overall cumulative impact assessment for each resource area, 

following guidance provided in NRC Staff Memorandum, Addressing Construction and 

Preconstruction Activities, Greenhouse Gas Issues, General Conformity Determinations, 

Environmental Justice, Need for Power, Cumulative Impact Analysis, and Cultural/Historical 

Resources Analysis Issues In Environmental Impact Statements (NRC 2010). The specific 

resources and components that could be affected by the incremental effects of the proposed 

action and other actions in the same geographic area were assessed. This assessment 

includes the impacts of construction and operations for the proposed new units as described in 

Chapters 4 and 5; impacts of preconstruction activities as described in Chapter 4; impacts of 

fuel cycle, transportation, and decommissioning impacts described in Chapter 6; and impacts of 

past, present and reasonably foreseeable future Federal, non-Federal, and private actions that 

could affect the same resources affected by the proposed actions. 

The review team visited the STP site in February 2008. The team then used the information 

provided in the ER, and in responses to Requests for Additional Information, information from 

other Federal and State agencies, and information gathered at the STP site visit to evaluate the 

cumulative impacts of building and operating two new nuclear power plants at the site. To 

inform the cumulative analysis, the review team researched Environmental Protection Agency 

(EPA) databases for recent EISs within Texas, used an EPA database for permits for water 

discharges in the area to identify water use projects, and used the www.recovery.gov website to 

identify projects in the geographic area funded by the American Recovery and Reinvestment 

Act of 2009 (Public Law 111-5). Other actions and projects that were identified during this 
Cumulative Impacts 

February 2011 7-3 NUREG-1937 

review and considered in the review team’s independent analysis of the cumulative effects are 

described in Table 7-1. 

Table 7-1. Past, Present, and Reasonably Foreseeable Future Projects and Other Actions 

Considered in the STP Cumulative Analysis. 

Project Name Summary of Project Location Status 

Energy Projects 

Operation and 

Decommissioning of 

South Texas Project 

Units 1 and 2 

Two 1265-MW(e) Westinghouse 

pressurized water reactors 

About 1500 ft 

south and 

2150 ft east 

of proposed 

center of 

Units 3 and 4 

Operational. STPNOC submitted an 

application for renewal of the 

operating licenses for Units 1 and 2 

in October 2010. If granted, the 

operating licenses would be 

extended for 20 years, or until 2047 

for Unit 1 and 2048 for Unit 2.(a)

White Stallion Energy 

Center (WSEC) 

Proposed 1320-MW baseload 

power plant fueled by a petroleum 

coke/bituminous coal combination 

About 5 mi 

northwest 

Proposed.(b) Four to five year 

project; construction is planned to 

begin in early 2011 and be 

completed by 2015. 

Victoria County Station One or more nuclear power 

reactors 

About 55 mi 

westsouthwest 

Proposed. Exelon Generation 

submitted an application to NRC for 

an early site permit (ESP) in March 

2010.(c)

Calhoun Liquefied 

Natural Gas (LNG) 

Terminal (Port Lavaca) 

LNG terminal on Port LavacaPoint Comfort About 25 mi 

westsouthwest 

Proposed.(d)

E.S. Joslin Power 

Plant Project (Port 

Lavaca) 

Proposed upgrade from 261-MW 

to 303-MW power plant fueled by 

petroleum coke 

About 25 mi 

westsouthwest 

The E.S. Joslin Power Plant 

operated from 1971 until 2004. 

Currently not operating; however, 

NuCoastal Power Corp plans to 

repower the plant. Air permits have 

been issued. Scheduled to be online 

by late 2012.(e)

Transmission Lines New transmission lines are not 

required for STP, but various 

transmission lines currently exist 

throughout region and installation 

of additional lines would occur if 

new nuclear plants such as the 

Victoria County Station or other 

large energy projects such as the 

WSEC are built. New transmission 

lines could require the following: 

widening of existing corridors, 

building new corridors, moving 

facilities within corridors, building 

new facilities within corridors. 

Throughout 

region 

Currently existing as well as the 

potential for additional transmission 

lines to be built 
Cumulative Impacts 

NUREG-1937 7-4 February 2011 

Table 7-1. (contd)

Project Name Summary of Project Location Status 

Water Resources 

Matagorda Ship 

Channel Improvement 

Project 

Widen and deepen the Matagorda 

Ship Channel by dredging. 

Port of Port 

Lavaca – 

Point 

Comfort 

Turning 

Basin 

through the 

Matagorda 

Bay to the 

Gulf of 

Mexico 

Proposed. Record of Decision 

issued November 2010.(f) 

Lower Colorado River 

Authority-San Antonio 

Water System (LCRASAWS) project 

Water sharing proposal to develop 

alternative water supplies that 

could help meet long-term needs 

in the lower Colorado River Basin 

and the San Antonio area. 

Delivery of water would occur 

from LCRA to SAWS. 

Entire Lower 

Colorado 

River Basin 

Proposed. Delivery of water from 

LCRA to SAWS could begin in 

2025.(g)

Mouth of the Colorado 

River Project 

Construct a channel to divert all 

Colorado River flow from the Gulf 

of Mexico into the Matagorda Bay 

Mouth of the 

Colorado 

River (approx 

4-5 mi southsoutheast) 

Constructed 1989-1992 by the 

Corps.(h)

Gulf Intracoastal 

Waterway (GIWW) 

Reroute 

Reroute of the GIWW across 

Matagorda Bay 

Matagorda 

Bay 

Completed(i)

Municipal diversions 

from the Colorado 

River 

Diversion for city water supplies Various 

locations 

along the 

Colorado 

River such as 

Bay City and 

Selkirk 

Operational 

Mary Rhodes Pipeline 

Phase II project 

Construct a 40-mi pipeline to 

divert water from the Lower 

Colorado River to Lake Texana for 

the City of Corpus Christi(k)

Between Bay 

City and 

existing Mary 

Rhodes 

Pipeline. 

Proposed. Anticipated in the 2020 to 

2030 time frame with a two to three 

year construction duration.(j) Actual 

implementation is dependent on 

increases in future demand. 

Municipal wastewater 

treatment facilities 

Matagorda, Beach Road 

Municipal Utility District, 

Wadsworth, Markham Municipal 

Utility District, Matagorda County, 

Bay City, Midfield, and the 

community of Selkirk 

Within 10 mi 

of STP 

Operational 
Cumulative Impacts 

February 2011 7-5 NUREG-1937 

Table 7-1. (contd)

Project Name Summary of Project Location Status 

East Jetty construction 

and pipeline dredging 

Sediment removal and channel 

excavation and repairs 

Colorado 

River and 

Tributaries, 

Texas mouth 

of Colorado 

River in 

Matagorda 

County 

Completed in October 2010(l)

Port of Bay City 

Authority Barge 

Terminal 

Barge terminal with a liquid cargo 

dock, a concrete dock, a low level 

heavy duty dock and a turning 

basin 

About 5 mi 

north 

Operational(m)

Parks 

Brazos Bend State 

Park 

Camping, picnicking, hiking, and 

fishing 

About 35 mi 

northeast 

Development unlikely in this park(n)

Clive Runnels Family 

Mad Island Marsh 

Preserve 

Natural preserve About 4 mi 

southwest 

Development unlikely in this 

preserve(o)

Mad Island Wildlife 

Management Area 

Wildlife management area About 3 mi 

south 

Development unlikely in this area(p)

Big Boggy National 

Wildlife Refuge 

Wildlife management area About 10 mi 

southwest 

Development unlikely in this area(q) 

Other Actions/Projects

Formosa Plastics 

Corporation 

Manufactures plastic resins and 

petrochemicals 

About 25 mi 

westsouthwest 

Operational(r)

Alcoa Aluminum Plant Aluminum manufacturing About 25 mi 

westsouthwest 

Operational(s)

Equistar Chemicals 

LP, Matagorda Facility 

Manufactures plastics, synthetic 

resins, and nonvulcanized 

elastomers 

About 4 mi 

east 

Operational(t)

OXEA Corporation, 

Bay City Plant 

(formerly Celanese) 

Manufactures organic chemicals About 3 mi 

northnortheast 

Operational(u, v)

Texas Liquid Fertilizer 

Co. Point Comfort 

Manufactures nitrogenous 

fertilizer 

About 25 mi 

westsouthwest 

Operational(w)

Various hospitals and 

industrial facilities that 

use radioactive 

materials 

Medical and other isotopes Within 50 mi Operational in nearby cities and 

towns 
Cumulative Impacts 

NUREG-1937 7-6 February 2011 

Table 7-1. (contd)

Project Name Summary of Project Location Status 

Future Urbanization Construction of housing units and 

associated commercial buildings; 

roads (such as the I-69 Corridor 

project), bridges, and rail; 

construction of water- and/or 

wastewater- treatment and 

distribution facilities and 

associated pipelines, as described 

in local land-use planning 

documents. There is a low 

potential for increased 

urbanization within Matagorda and 

Brazoria counties as population 

growth is expected to be less than 

2 percent per year (see 

Table 2-17). 

Throughout 

region 

Construction would occur in the 

future, as described in State and 

local land use planning documents(x)

(a) Source: STPNOC 2010c 

(b) Source: WSEC 2010 

(c) Source: Exelon 2010 

(d) Source: FERC 2007 

(e) Source: O’Grady 2008 

(f) Source: Corps 2010a 

(g) Source: LCRA-SAWS 2006 

(h) Source: Onvia Inc. 2009 

(i) Source: TxDOT 2000 

(j) Source: Neuces River Authority 2001 

(k) Source: City of Corpus Christi 2009 

(l) Source: Corps 2010b 

(m) Source: Port of Bay City Authority 2010 

(n) Source: TPWD 2009a 

(o) Source: The Nature Conservancy 2009 

(p) Source: TPWD 2009b 

(q) Source: FWS 2010 

(r) Source: EPA 2009a 

(s) Source: EPA 2009b 

(t) Source: EPA 2009c 

(u) Source: EPA 2009d 

(v) Source: EPA 2009e 

(w) Source: EPA 2009f 

(x) Source: TxDOT 2010 
Cumulative Impacts 

February 2011 7-7 NUREG-1937 

7.1 Land Use 

The description of the affected environment in Section 2.2 serves as a baseline for the 

cumulative impacts assessment in this resource area. As described in Section 4.1, the review 

team concludes that the impacts of NRC-authorized construction on land use would be SMALL 

and no further mitigation would be warranted. As described in Section 5.1, the review team 

concludes that impacts of operations on land use would also be SMALL and no further 

mitigation would be warranted. 

The combined impacts from construction and preconstruction are described in Section 4.1 and 

determined to be SMALL. In addition to land-use impacts from construction, preconstruction, 

and operation, the cumulative analysis also considers other past, present, and reasonably 

foreseeable future actions that could contribute to cumulative impacts to land use. For this 

cumulative analysis, the geographic area of interest is the area within a 15-mi radius of the 

proposed STP site. The review team determined that a 15-mi radius would represent the 

largest area that would be directly affected because it includes the primary communities (the 

largest being Bay City) that would be affected by the proposed project. A radius larger than 

15 mi would include land areas that would not be directly affected by the proposed project. 

Historically, the STP site and vicinity was a relatively flat coastal plain with farmland and pasture 

land predominating. Residential development in Matagorda County began in the 1800s and 

accelerated when construction of Units 1 and 2 began in the 1970s. Much of the STP site was 

affected by building Units 1 and 2. The general trend in the 15-mi geographic area of interest 

over the past few decades has been a gradual increase in residential areas, roads, utilities, and 

businesses and a small decrease in wetlands and agricultural lands. 

As described in Section 4.1, there would be a loss of undeveloped land and habitat (see 

Table 4-2 for the types of affected acreage) at the STP site from development related to the 

proposed project. No new offsite transmission corridors or expansion of existing corridors are 

planned for proposed Units 3 and 4. Although there would be upgrades and maintenance to 

existing transmission lines, these activities would not result in any offsite land use changes. 

STPNOC applied for renewal of its operating licenses for STP Units 1 and 2 for an additional 

20 years (STPNOC 2010c). It is not anticipated that any new areas on the STP site would be 

converted to industrial use if the license renewals are granted. 

Within the 15-mi geographic area of interest, the reasonably foreseeable future project with the 

greatest potential to affect land use would be the proposed WSEC project. If constructed, the 

WSEC would be located on a 1200-ac tract of land approximately 5 mi northwest of the STP site 

(WSEC 2009). The workers, especially construction workers, would likely be drawn from a wide 

area, dispersing any potential land-use impacts from workers. The WSEC project would require 

at least one new transmission line corridor within the 15-mi review area. If the WSEC were to 
Cumulative Impacts 

NUREG-1937 7-8 February 2011 

be constructed, the review team concludes that the land-use impacts of the project within the 

15-mi review area would be sufficient to alter noticeably, but not destabilize, important attributes 

of land use. 

Future urbanization in the review area and global climate change (GCC)—two trends that are 

difficult to predict—could contribute to additional decreases in open areas, forests, and 

wetlands. Urbanization in the vicinity of STP would alter important attributes of land use. 

Urbanization would reduce natural vegetation and open space, resulting in an overall decline in 

the extent and connectivity of wetlands, forests, and wildlife habitat. GCC could reduce crop 

yields and livestock productivity (GCRP 2009), which may change portions of agricultural and 

ranching land uses in the area of interest. In addition, GCC could increase sea level and storm 

surges in the area of interest (GCRP 2009), thus changing land use through inundation and loss 

of coastal wetlands and other low-lying areas. However, existing parks, reserves, and managed 

areas would help preserve wetlands and forested areas to the extent that they are not affected 

by sea-level rise. Future urbanization trends and direct changes resulting from GCC could 

noticeably alter land uses in the geographic area of interest. 

Based on its evaluation, the review team concludes that the cumulative land-use impacts 

associated with proposed Units 3 and 4 and other projects in the 15-mi geographic area of 

interest, including the proposed WSEC project, would be MODERATE. The land-use impacts 

would be sufficient to alter noticeably, but not destabilize, important attributes of land use. The 

incremental land-use impacts associated with the proposed WSEC project and the associated 

transmission corridor(s) for the project and the changes resulting from future urbanization and 

GCC are the principal contributors to the MODERATE characterization of cumulative land-use 

impacts. The NRC staff concludes that the incremental impacts of NRC-authorized activities 

would be SMALL, and would not contribute significantly to the MODERATE impact 

characterization. 

7.2 Water Use and Quality 

This section analyzes the cumulative impacts of the proposed new units, the existing STP Units 

1 and 2, and other past, present, and reasonably foreseeable future projects on water use and 

water quality. 

7.2.1 Water Use Impacts 

As stated in Section 2.3.2, water use in Texas is regulated by the Texas Water Code. As 

established by Texas Water Code, surface water belongs to the State of Texas (Texas Water 

Code, Chapter 11, Section 11.021). The right to use surface waters of the State of Texas can 

be acquired in accordance with the provisions of the Texas Water Code, Chapter 11. In Texas, 

surface water is a commodity. Since the Colorado River Basin is currently heavily appropriated, 
Cumulative Impacts 

February 2011 7-9 NUREG-1937 

future water users in this basin would likely obtain surface water by purchasing or leasing 

existing appropriations. Regarding groundwater, Texas law has allowed landowners to pump 

the water beneath their property without consideration of impacts to adjacent property owners 

(NRC 2009). However, Chapter 36 of Texas Water Code authorized groundwater conservation 

districts to help conserve groundwater supplies. Chapter 36, Section 36.002, Ownership of 

Groundwater, states that ownership rights are recognized and that nothing in the code shall 

deprive or divest the landowners of their groundwater ownership rights, except as those rights 

may be limited or altered by rules promulgated by a district. Thus, groundwater conservation 

districts with their local constituency offer groundwater management options (NRC 2009). 

Existing projects in Texas have appropriations to use water for their requirements. STPNOC 

has stated that proposed Units 3 and 4 would operate within the limits of these existing surface 

water and groundwater appropriations (STPNOC 2010a). The review team expects that future 

projects would do so, as well. 

Climate Change 

On a larger spatial and longer time scale, GCC is a subject of national and international interest. 

The recent compilation of the state of knowledge by the U.S. Global Change Research Program 

(GCRP), a Federal Advisory Committee, has been considered in preparation of this EIS (GCRP 

2009). Within the Colorado River Basin, changes in temperature and precipitation are projected 

by 2080-2099. In Section 2.9.1, the review team discussed changes to temperature and 

precipitation resulting from global climate change forecasted by GCRP for the vicinity of the site. 

The review team determined that the forecasted changes could affect water supply and water 

quality in the Colorado River Basin during the operational life of the proposed STP Units 3 

and 4. 

For the water use and water quality assessments discussed below, the review team considered 

forecasted changes to temperature and precipitation for the entire Colorado River watershed. 

The projected change in temperature from ‘present day’ (1993-2008) to the period 

encompassing the licensing action (i.e., the period of 2040 to 2059 in the GCRP report) for the 

Colorado River watershed is an increase of between 0 to 5°F. While the GCRP has not 

incrementally forecasted the change in precipitation by decade to align with the licensing action, 

the projected change in precipitation from the ‘recent past’ (1961-1979) to the period 2080 to 

2099 is a decrease of between 10 to 30 percent (GCRP 2009). The GCRP assessment also 

identified this region as likely to experience water conflicts by 2025 based on a combination of 

factors including population trends and potential endangered species’ needs. Declines in 

aquifer water levels are likely to continue throughout Texas, as the aquifers, such as the 

Ogallala, are increasingly relied on in response to drought in Texas and the larger Great Plains 

region (GCRP 2009). Such changes in climate could result in adaptations to both surface water 

and groundwater management practices and policies that are unknown at this time. 
Cumulative Impacts 

NUREG-1937 7-10 February 2011 

7.2.1.1 Surface Water-Use Impacts 

The description of the affected environment in Section 2.3 serves as a baseline for the 

cumulative impacts assessments in this resource area. As described in Section 4.2, the 

impacts from NRC-authorized construction on surface water use would be SMALL, and no 

further mitigation would be warranted. As described in Section 5.2, the review team concludes 

that the impacts of operations on surface water use would also be SMALL, and no further 

mitigation would be warranted. 

The combined surface water-use impacts from construction and preconstruction are described 

in Section 4.2.2 and determined to be SMALL. In addition to the impacts from construction, 

preconstruction, and operations, the cumulative analysis also considers other past, present, and 

reasonably foreseeable future actions that would affect surface water use, including potential 

effects of GCC, as discussed above. The Lower Colorado Regional Water Planning Area, or 

Region K, includes all or part of 14 counties that extend from Mills and San Saba Counties in 

the northwest to Matagorda County in the southeast. For the cumulative analysis of impacts on 

surface water, the geographic area of interest is the drainage basin of the Colorado River and 

Matagorda Bay in Region K because the effects on other actions within this region could interact 

with the effects of the proposed project and result in a cumulative impact. The Region K 

boundaries do not completely coincide with county boundaries or the Colorado River Basin 

watershed boundary. The current water planning time period for the Region is through 2060. 

The Colorado River has provided water for agricultural, industrial, and municipal use since this 

region was settled. Dams have been installed on the river to provide flood control, increase the 

reliability of water supply to the region, and to provide power. Key past and present actions that 

have potential impacts on surface-water supply in the Colorado River Basin include construction 

and operation of upstream water supply dams, construction and operation of STP Units 1 and 2, 

and diversion of water from the river for current surface water use. 

Other existing and reasonably foreseeable future actions in the geographic area of interest 

include the operation of STP Units 1 and 2, the LCRA-SAWS project, the proposed WSEC 

project, the proposed Phase II expansion of the Mary Rhodes pipeline for delivery of 

35,000 ac-ft/yr of water to the City of Corpus Christi, current surface withdrawals for municipal, 

industrial, and irrigation use, potential impacts from GCC, and the additional water demand 

created by population growth in the region. The impacts of other projects listed in Table 7-1 

would have little or no impact on surface-water use. 

As discussed in Section 4.2.2, STPNOC has proposed no surface water use during site 

development. The expected average long-term consumptive surface-water use of proposed 

Units 3 and 4 would be 34,850 ac-ft/yr (21,600 gpm) at 93 percent load factor and 

37,430 ac-ft/yr (23,190 gpm) at 100 percent load factor (STPNOC 2009a). The existing STP 

Units 1 and 2 diverted an average of 37,084 ac-ft/yr (22,990 gpm) from the Colorado River from 
Cumulative Impacts 

February 2011 7-11 NUREG-1937 

2001 through 2006 (STPNOC 2010a). The estimated average long-term consumptive water 

use of STP Units 1 and 2 is estimated to be 33,200 ac-ft/yr (20,580 gpm) at 93 percent load 

factor and 37,200 ac-ft/yr at 100 percent load factor (STPNOC 2009a). Together, under normal 

operations, all four STP units would consume approximately 68,050 ac-ft/yr (42,190 gpm) at 

93 percent load factor and 74,630 ac-ft/yr (46,268 gpm) at 100 percent load factor. The 

average water diverted for existing STP Units 1 and 2 and the expected water use for all four 

STP units are estimated to be 2 and 4 percent, respectively, of the annual mean daily discharge 

in the Colorado River at the Bay City U.S. Geological Survey (USGS) gauge based on 

1949-2008 streamflow data (discussed in Section 5.2). If no water management strategies are 

implemented in Region K, the combined water use of existing and proposed units at the STP 

site would be 6 percent of the current estimated water supply and 8 percent of the available 

2060 water supply. Water management strategies are used to conserve, reuse, or develop 

water supplies. Development of water supplies includes building new water supply reservoirs, 

and developing unused aquifers underlying the region (TWDB 2006b). Implementation of water 

management strategies results in increased available water within a region. The review team 

concludes that the surface water use impact of operating all four units at the STP site would be 

minimal if all water management strategies are implemented, and would be noticeable if no 

water management strategies are implemented. 

A water-sharing project between the LCRA and the SAWS, in Water Planning Regions K and L, 

respectively, is currently undergoing a feasibility study (LCRA 2009a) and would impact water 

resources in the geographic area of interest. Region L is located to the south and west of 

Region K. A set of conservation and storage strategies would conserve and develop surface 

and groundwater resources in the lower Colorado River Basin to provide water for both 

Regions—although no groundwater would be sent from Region K to Region L. An off-channel 

holding basin in Wharton County (LCRA 2009b) would be used to store water for the LCRASAWS project. The planned project would provide 377,000 ac-ft/yr of water to users in the two 

Regions (TWDB 2006a); Region L would receive 150,000 ac-ft/yr from Region K starting in the 

2020 decade (TWDB 2006b). The Region L diversion of 150,000 ac-ft/yr would be 

approximately 9 and 17 percent of the 2060 water supply in Region K with and without 

implementation of water management strategies, respectively. If the LCRA and SAWS boards 

determine that the project is technically feasible, the permitting process is planned for 

2010-2015, followed by construction during 2015-2025, with water delivery to SAWS to start in 

2025. The LCRA-SAWS diversion would have a noticeable impact on surface water resources 

of Region K. The LCRA-SAWS water project is currently on hold because of ongoing legal 

proceedings and it is probable that the project will be cancelled (LCRA 2010). However, no final 

announcement of project cancellation has been made (LCRA 2010). 

A 1320-MW power plant, the WSEC, listed in Table 7-1, is proposed in Matagorda County near 

Farm-to-Market (FM) Road 2668 approximately 1 mi south of Port of Bay City and 

approximately 5 mi northeast of the STP site (WSEC 2010). On October 13, 2008, the WSEC 
Cumulative Impacts 

NUREG-1937 7-12 February 2011 

applied to LCRA for a new firm water supply of 22,000 ac-ft/yr (LCRA 2009c). The total 

diversion from the Colorado River would be 29,750 ac-ft/yr, accounting for delivery losses. At 

this time, no other details regarding WSEC diversion are available. The WSEC water use of 

22,000 ac-ft/yr would be 2 percent of the current estimated water supply and 2.5 percent of the 

2060 water supply in Region K without implementation of water management strategies, and 

1 percent of the 2060 Region K water supply with implementation of all water management 

strategies. The review team concludes that the surface water use impact of the WSEC project 

would be minimal. 

As stated in Section 2.3.2.1, the City of Corpus Christi has a water right amounting to 

35,000 ac-ft/yr from the Colorado River. The City of Corpus Christi may exercise its currently 

unused water rights from the Colorado River in the 2020 to 2030 time frame or sooner 

depending on demand (City of Corpus Christi 2010). Currently, Phase I of Mary Rhodes 

Pipeline delivers water from Lake Texana to the City. To use its water right from the Colorado 

River, the City would build Phase II of Mary Rhodes Pipeline from Bay City to Lake Texana. 

The review team estimated that the City’s 35,000 ac-ft/yr water right would be 3 percent of the 

current estimated water supply and 4 percent of the 2060 water supply in Region K without 

implementation of water management strategies, and 2 percent of the 2060 Region K water 

supply with implementation of all water management strategies. Because this use constitutes 

such a small percentage of the water supply, the review team concludes that the surface water 

use impact from the City’s 35,000 ac-ft/yr of water right would be minimal in the region. 

Downstream of the STP site, there are no users of Colorado River waters except for freshwater 

inflow needs for the Matagorda Bay. The LCRA, Texas Commission on Environmental Quality 

(TCEQ), Texas Parks and Wildlife Department (TPWD), and the Texas Water Development 

Board (TWDB) (LCRA et al. 2006) updated an earlier 1997 freshwater inflow needs study for the 

Matagorda Bay. The study used two measures for freshwater inflow to the bay: (1) the target 

freshwater inflow need that would optimize the productivity of selected estuarine species and 

(2) the critical freshwater inflow need that would promote the repopulation of finfish and shellfish 

species following a dry period. The average monthly target freshwater inflow was estimated to 

be 118,975 ac-ft per month (1972 cubic feet per second [cfs]) from the Colorado River into the 

Bay. The critical freshwater inflow was estimated to be 36,000 ac-ft per month (597 cfs). This 

situation continues to be evaluated. A habitat assessment study for the Matagorda Bay by 

LCRA-SAWS evaluated the effects of the alteration to freshwater inflow into Matagorda Bay as 

part of the LCRA-SAWS project and to aid in the development of freshwater inflow criteria 

(LCRA-SAWS 2006). LCRA-SAWS Matagorda Bay Health Evaluation team has provided 

recommendations for freshwater inflow needs that would be protective of Matagorda Bay health 

and productivity (LCRA-SAWS 2008). These recommendations are currently under review by 

the TCEQ. A freshwater inflow need, when established, could make that amount of surface 

water unavailable for other use. 
Cumulative Impacts 

February 2011 7-13 NUREG-1937 

The operation of existing and proposed units at the STP site, the WSEC project, the proposed 

Phase II expansion of the Mary Rhodes pipeline for delivery of 35,000 ac-ft/yr of water to the 

City of Corpus Christi, and the LCRA-SAWS project together would use 24 percent of the 

estimated 2010 water supply in Region K. With the anticipated implementation of the proposed 

water management strategies (TWDB 2006b), the combined water used by the projects listed 

above would be 16 percent of the Region K 2060 water supplies. The combined water used by 

the projects listed above would be 32 percent of the Region K 2060 water supply without 

implementation of any new water management strategies. The review team concludes that the 

combined water use of the existing and proposed units at the STP site, the WSEC project, 

future water use by the City of Corpus Christi, and the LCRA-SAWS project would result in a 

noticeable but not destabilizing impact on the surface water resources of Region K. As stated 

above, implementation of water management strategies results in additional water available for 

use. 

In addition to the specific projects listed in Table 7-1, continued population growth is anticipated 

in the geographic area of interest. In the 2007 State Water Plan, the TWDB stated that the 

population of the State of Texas is expected to grow to 46 million by 2060 and the demand for 

water is expected to increase to 21.6 million ac-ft in 2060 (TWDB 2006b). The existing surface 

and groundwater supplies are estimated to be 17.9 million ac-ft in 2010 and would decrease to 

14.6 million ac-ft in 2060 because of sediment accumulation in reservoirs and depletion of 

aquifers (TWDB 2006b). There is a low potential for increased urbanization within Matagorda 

and Brazoria Counties, as population growth is expected to be less than 2 percent per year (see 

Table 2-17), which would have a minimal impact on water use in the region. 

The 2060 estimated shortfall in water supply from growth in demand and reduction in water 

supply due to sedimentation of reservoirs and expiration of water contracts is 413,710 ac-ft/yr. 

However, the TWDB plans to develop, conserve, and share water supplies that would yield an 

additional water supply of 550,658 ac-ft/yr in Region K by 2060. TWDB (2007) concluded that 

the water demand in 2060 can be met by implementing the proposed strategies. 

The diversion of surface water to Region L from Region K as part of the LCRA-SAWS project 

and the City of Corpus Christi’s Colorado River water right are already accounted for in the 2007 

State Water Plan (TWDB 2006b). The current STPNOC water right of 102,000 ac-ft/yr for 

existing and proposed units (LCRA-STPNOC 2006) is also accounted for in Region K planning 

(TWDB 2006b). The proposed water use by WSEC is not included in the 2007 State Plan. 

Therefore, the planned water management strategies would need to account for the additional 

22,000 ac-ft/yr of water use proposed by the WSEC project. Without the WSEC water use 

accounted for, the estimated excess water supply with the implementation of water 

management strategies in 2060 is estimated to be 136,948 ac-ft/yr. The review team concludes 

that with implementation of water management strategies, the impact of future projects on the 

surface water resources of Region K would be noticeable, but not destabilizing. 
Cumulative Impacts 

NUREG-1937 7-14 February 2011 

Historically, the waters of the Colorado River Basin have been used extensively. Therefore, as 

discussed above, the region has surface water planning, allocation, and development systems 

in place to manage the use of its limited surface water resources. These efforts are described 

in the Regional and State Water Plans (TWDB 2006a, b). The review team has reviewed the 

regional and State plans and other publicly available information. The cumulative impact on 

surface water use in the Colorado River and Matagorda Bay drainages in Region K to the 

unaltered conditions prior to these uses, from past and present diversions and reasonably 

foreseeable future projects, would noticeably alter but not destabilize the surface water 

resource, and therefore would be MODERATE. The incremental impacts from the proposed 

action and NRC-authorized activities would be SMALL and would not noticeably alter water use 

in Region K. No further mitigation beyond that described in Chapters 4 and 5 would be 

warranted. 

As stated above, GCC could result in decreased precipitation and increased temperatures in the 

lower Colorado River Basin. These forecasted changes have the potential to reduce surface 

runoff and increase evapotranspiration. The changes may result in reduction in the surface 

water resource in the region. While these changes from GCC may not be insignificant nationally 

or globally, the review team has not identified anything that would alter the conclusions 

presented above regarding surface water use in the geographical area of interest. 

7.2.1.2 Groundwater-Use Impacts 

The description of the affected environment in Section 2.3 serves as a baseline for the 

cumulative impacts assessments in this resource area. As described in Section 4.2, the 

impacts from NRC-authorized construction on groundwater use would be SMALL, and no 

further mitigation would be warranted. As described in Section 5.2, the review team concludes 

that the impacts of operations on groundwater use would also be SMALL, and no further 

mitigation would be warranted. 

The combined groundwater-use impacts from construction and preconstruction are described in 

Section 4.2.2 and determined to be SMALL. In addition to the impacts from construction, 

preconstruction, and operations, the cumulative analysis also considers other past, present, and 

reasonably foreseeable future actions that could affect groundwater use, including potential 

effects of GCC, as discussed above. For this analysis, two geographic areas of interest have 

been identified. For the Shallow Aquifer, which would be impacted by dewatering, the area of 

interest for construction and preconstruction is limited to the STP site. For the Deep Aquifer, 

which would be affected by water withdrawn for construction, preconstruction, and operation of 

proposed Units 3 and 4, the geographic area of interest extends from recharge areas in 

Wharton County to Matagorda Bay. 

Groundwater use from the Gulf Coast Aquifer system increased between 1940 and the mid1980s, primarily from the increase in water withdrawals for rice irrigation, and Matagorda County 
Cumulative Impacts 

February 2011 7-15 NUREG-1937 

was among the counties where this occurred (Ryder 1996). Impacts of overpumping the 

groundwater resource included land subsidence, saltwater intrusion, stream base-flow 

depletion, and increased pumping lift. Groundwater use from the Gulf Coast Aquifer system has 

since declined because of these issues and the TWDB forecasts a continued decline in 

groundwater use in the Gulf Coast Aquifer through 2030. The USGS in 2002 projected a net 

decrease of 48 percent in groundwater pumping from 1985 levels (Ryder and Ardis 2002). 

As discussed in Section 4.2.2, STPNOC currently holds a groundwater use or operating permit 

to withdraw from the Deep Aquifer. The Deep Aquifer would be the sole source of groundwater 

used during Units 3 and 4 building activities and, as discussed in Section 5.2.2.2, would be used 

as the source of makeup water for the proposed Units 3 and 4 Ultimate Heat Sink (UHS), 

service water for the power plants, fire protection systems, and water for potable and sanitary 

systems. Projects listed in Table 7-1 that are in the geographic area of interest that could 

contribute to cumulative impacts on the Deep Aquifer include operation of STP Units 1 and 2, 

Equistar Chemicals LP’s Matagorda facility, the OXEA Corporation Bay City plant and municipal 

water supplies for Bay City and the nearby community of Selkirk. 

Aside from STP Units 1 and 2, the closest of the projects identified in Table 7-1 are 3 to 4 mi 

from the proposed location of Units 3 and 4. The closest community having groundwater 

production wells is Selkirk, which is located immediately east of the STP site’s eastern 

boundary, and the closest STP groundwater production well is located about 1 mi from this 

community. Each of the above-listed users of the groundwater resource does so under the 

rules of the Coastal Plains Groundwater Conservation District (CPGCD) (CPGCD 2009). The 

purpose of the CPGCD (2009) is to provide for the conserving, preserving, protecting, and 

recharging of the groundwater to control subsidence and prevent the waste and pollution of the 

groundwater resource. While potential impacts from groundwater use include excessive 

drawdown, saltwater intrusion, or land subsidence, groundwater use under the rules of the 

CPGCD is designed to minimize the potential for these impacts to arise and affect neighboring 

groundwater users (CPGCD 2009). Accordingly, no projects listed in Table 7-1, other than STP 

Units 1 and 2, would contribute substantially to cumulative impacts on the Deep Aquifer in the 

vicinity of the STP site. Because the Deep Aquifer wells providing groundwater to STP Units 1 

and 2 would also be used to provide groundwater to STP Units 3 and 4, their impacts are 

cumulative. Groundwater impacts at wells located 2500 ft from the STP site are included in 

Chapters 4 and 5. Because the closest offsite water supply wells are farther than 2500 ft from 

STP wells, the effects quantified in Chapters 4 and 5 bound the effect these wells have on one 

another. 

Given that the geographic area of interest for the Shallow Aquifer is limited to the STP site 

(i.e., the on-site dewatering activities), no projects listed in Table 7-1, other than Units 1 and 2, 

would contribute to cumulative impacts on the Shallow Aquifer. 
Cumulative Impacts 

NUREG-1937 7-16 February 2011 

The USGS has forecast a decline in groundwater use in Matagorda County based on historical 

record and changes in groundwater resource use (Ryder and Ardis 2002). Recent groundwater 

use, however, reflects current drought conditions and exhibits an increase in groundwater use 

over that seen in the late 1990s, but not a return to the previously seen high usage rates of the 

1980s. With the exception of STP Units 1 and 2, other groundwater users are sufficiently distant 

from the site so that groundwater withdrawals supporting proposed Units 3 and 4 would have 

minimal impact on the groundwater resources for these users. The affected environment 

described in Chapter 2 and the review team’s assessments in Section 4.2.2 and Section 5.2.2.2 

reflected the groundwater used by current users including operation of STP Units 1 and 2 

(i.e., baseline groundwater levels include the influence of existing groundwater use). 

The potential offsite impact on the groundwater resource during the operation of four STP units 

would be represented by the normal operation groundwater requirement of 9000 ac-ft/yr over 

the approximately 3-year term of the groundwater use permit, which is the maximum usage 

allowed under the groundwater use permit held by STP (CPGCD 2008). This current permit 

limit would also be used during operation of existing STP Units 1 and 2, and construction, 

preconstruction, and operation of proposed Units 3 and 4 at STP. Based on estimates of the 

current groundwater use and the available groundwater resource (Section 2.3.2.2), future STP 

groundwater use totaling 1860 gpm for the four units represents approximately 10 percent of 

current usage in Matagorda County and 6 percent of the available groundwater resource within 

the CPGCD. Because the managed available groundwater resource is not exceeded in the 

CPGCD, these levels of groundwater use have minimal impact on the groundwater resource 

within the district. An evaluation of drawdown resulting from the operation of proposed Units 3 

and 4 is presented in Section 5.2.2.2. A similar analysis of the drawdown resulting from 

groundwater withdrawal to support all four STP units provides similar results and demonstrates 

that the drawdown would be substantially less than the confining pressure in the aquifer prior to 

operations of all four units at the STP site, resulting in minimal impact to the regional 

groundwater resource. 

Groundwater use is declining regionally and therefore subsidence is expected to be less of an 

issue regionally over the life of the operation of the proposed units. The Updated Final Safety 

Analysis Report (UFSAR) for Units 1 and 2 projected regional subsidence from 1973 through 

2020 to be between 2.5 to 3 ft based on a projected regional groundwater decline of 87 ft and 

subsidence coefficients derived from regional observations (UFSAR Section 2.5.1.2.9.6.3) 

(STPNOC 2008c). In the Final Safety Analysis Report (FSAR) Section 2.5S.1.2.6.5 (STPNOC 

2010b) STPNOC estimated the maximum subsidence at the STP site because of excavation 

dewatering is between 0.04 and 0.05 ft. In FSAR Section 2.4S.12.4 (STPNOC 2010b) 

STPNOC commits to expanding the ongoing plant subsidence monitoring program to include 

the proposed Units 3 and 4. 
Cumulative Impacts 

February 2011 7-17 NUREG-1937 

The review team is also aware of the potential climate changes that could affect groundwater 

use. A recent compilation of the state of knowledge in this area (GCRP 2009) has been 

considered in the preparation of this EIS. Projected changes in the climate for the region during 

the life of proposed Units 3 and 4 include an increase in average temperature and a decrease in 

precipitation. This may result in less groundwater recharge. While the changes that are 

attributed to climate change in these studies may not be insignificant nationally or globally, the 

review team did not identify anything that would alter its conclusion regarding local groundwater 

use below. 

The impacts associated with other groundwater users in the region and the projections that 

groundwater use by others in the region could decrease in the future were considered in the 

analysis performed in Chapters 4 and 5. Based on the presence of sufficient confining head to 

maintain a confined aquifer and a groundwater resource sufficient to sustain the projected site 

groundwater use, the review team concludes that the cumulative effects to the groundwater 

resource from preconstruction, construction, and operation of STP Units 3 and 4, and other 

past, present, and reasonably foreseeable future projects would be minimal, including the 

potential of decreased precipitation and increased temperatures due to GCC. Therefore, the 

review team concludes that cumulative impacts of groundwater use would be SMALL, and no 

further mitigation beyond that described in Chapters 4 and 5 would be warranted. 

7.2.2 Water-Quality Impacts 

This section describes cumulative water-quality impacts from construction, preconstruction, and 

operations of proposed Units 3 and 4, and other past, present, and reasonably foreseeable 

future projects. 

7.2.2.1 Surface-Water Quality Impacts 

The description of the affected environment in Section 2.3 of this document serves as a 

baseline for the cumulative impacts assessments in this resource area. As described in 

Section 4.2, the impacts from NRC-authorized construction on surface water quality would be 

SMALL, and no further mitigation would be warranted. As described in Section 5.2, the review 

team concludes that the impacts of operations on surface water quality would also be SMALL, 

and no further mitigation would be warranted. 

The combined surface water-quality impacts from construction and preconstruction are 

described in Section 4.2.3.1 and determined to be SMALL. In addition to the impacts from 

construction, preconstruction, and operations, the cumulative analysis also considers other past, 

present, and reasonably foreseeable future actions that could affect surface water quality, 

including the potential effects of GCC. For the cumulative analysis of impacts on surface water, 

the geographic area of interest is the drainage basin of the Colorado River upstream and 

downstream of the STP site because other actions within this region could result in a cumulative 

impact. 
Cumulative Impacts 

NUREG-1937 7-18 February 2011 

Historically, point and nonpoint pollution sources have impaired the quality of the Colorado 

River. Water quality in the Colorado River has been affected by nonpoint source effluents in 

the river basin such as agricultural runoff. TCEQ has a Total Maximum Daily Load program 

in place to restore waters to their designated use, pursuant to Section 303 of the Clean 

Water Act (TCEQ 2010a). The segment of the river near the STP site is impaired and is 

listed on the State’s 303(d) list, a list that identifies water bodies in or bordering Texas for 

which effluent limitations are not stringent enough to implement water quality standards, and 

for which the associated pollutants are suitable for measurement by maximum daily load 

(TCEQ 2010b). As such, restoration of the Colorado River is the focus of several current 

and planned Federal, State, and local efforts. 

Other present and reasonably foreseeable future actions in the geographic area of interest of 

the proposed Units 3 and 4 site include the continued operation of STP Units 1 and 2, the 

LCRA-SAWS project, the proposed WSEC project, current waste water treatment plant 

discharges (Matagorda, Beach Road, Wadsworth, Markham, Matagorda County, Bay City, 

Midfield), additional water demand created by population growth in the region, and potential 

decreases in precipitation and increased temperatures due to GCC. The impacts of other 

projects listed in Table 7-1 would have little or no impact on surface-water use. 

The impact on surface water quality from construction and preconstruction activities would be 

minimal because impacts would be localized and temporary, as described in Section 4.2.3. 

Impacts during operations would also be minimal because any chemicals or radiological 

contaminants would be diluted, as described in Section 5.2.3. In addition to discharges from 

proposed Units 3 and 4, STP Units 1 and 2 would also have future discharges from the Main 

Cooling Reservoir (MCR) to the Colorado River. The bounding scenario of discharge thermal 

plume formation described in Section 5.2.3.1 includes the potential effects of the operation of 

existing and proposed units at the STP site on the water quality of the Colorado River. The 

review team determined that the thermal plume caused by a bounding discharge scenario would 

not completely block the river cross section and the chemical or radiological constituents of the 

discharge would be diluted at least eight times, as such, the thermal and chemical effects of the 

discharge plume during operation of all four units would not be significant. The review team 

also determined that the plume constituents would be quickly transported downstream to 

Matagorda Bay where they would undergo further dilution. The review team concluded, 

therefore, that the impact on surface water quality, from operation of existing and proposed units 

at the STP site would not be noticeable. 

Water quality in the Colorado River could also be affected by projects that discharge effluents 

upstream or downstream of the STP site such as municipal wastewater treatment plants. In 

such cases, if the additional discharges from other projects were to occur sufficiently close to 

the point of discharge used by the STP units, the water quality alterations within the Colorado 

River could be amplified by combination of the individual discharges. The WSEC project site is 
Cumulative Impacts 

February 2011 7-19 NUREG-1937 

located approximately 5 mi northeast of the STP site. The WSEC project has requested a water 

use permit for 22,000 ac-ft/yr from TCEQ. The project would likely use water withdrawn from 

the Colorado River. There are no other details available regarding the cooling system that the 

WSEC would employ and the amount of cooling water and other effluent discharge to the 

Colorado River. The review team conservatively assumed that the WSEC project would 

discharge to the Colorado River approximately 6 mi upstream of the location of the MCR 

discharge ports. The power generation capacity of the WSEC (1320 MW) is smaller than that of 

the existing and proposed units at the STP site (5130 MW). Therefore, the review team 

assumed that the discharge plume from a cooling system similar to the one employed by the 

STP units would also be smaller. The WSEC project would also need to obtain a Texas 

Pollutant Discharge Elimination System (TPDES) permit to discharge effluent to the Colorado 

River and therefore would be subject to conditions similar to those placed on the STP discharge 

by the State. The effects of the WSEC effluent discharge would be transported approximately 

6 mi downstream to the STP MCR discharge ports where their effects may combine with the 

effects of a concurrent MCR discharge. The review team determined that there is sufficient 

separation between the two projects’ discharge locations for the WSEC plume to dissipate 

before reaching the STP discharge ports and therefore only slight increases in constituent 

concentration or water temperature would be anticipated during a concurrent discharge from 

both projects, and the cumulative impact to Colorado River water quality would be minimal. 

As stated in Section 2.3.1.1, it is reasonably foreseeable that sea level rise may exceed 3 ft by 

the end of the century due to GCC (GCRP 2009). Actual changes in shorelines would also be 

influenced by geological changes in shoreline regions (such as subsidence). The increase in 

sea level relative to the Colorado River bed, coupled with reduced streamflow (also due to 

GCC), could result in the salt water front in the Colorado River moving up towards the Reservoir 

Makeup Pumping Facility (RMPF). 

As stated above, GCC could result in decreased precipitation and increased temperatures in the 

Lower Colorado River Basin. These forecasted changes have the potential to reduce surface 

runoff, increase evapotranspiration, change cropping patterns, and alter nutrient loadings to 

runoff. The changes may result in alteration to the surface water quality in the region. While 

these changes from GCC may not be insignificant nationally or globally, the review team has not 

identified anything that would alter the conclusions presented above regarding water quality of 

the Colorado River adjacent to the site. 

Historically, point and nonpoint pollution sources have impaired the quality of the Colorado 

River, and as such, the segment of the river near the STP site is impaired and is listed on the 

State’s 303(d) list. Because water quality in the Colorado River in the vicinity of the STP site is 

already impaired from past and current actions, the review team concludes that the cumulative 

impact on surface water quality from construction, preconstruction, and operation of Units 3 and 

4, and from other past, present, and reasonably foreseeable future projects, and potential 
Cumulative Impacts 

NUREG-1937 7-20 February 2011 

effects of GCC, would be MODERATE. Other point and nonpoint pollution sources in the 

Colorado River Basin are the principal contributors to this cumulative impact characterization. 

The incremental impacts from the proposed action, and NRC-authorized activities, would be 

SMALL and would not noticeably alter water quality of the Colorado River. No further mitigation 

beyond that described in Chapters 4 and 5 would be warranted. 

7.2.2.2 Groundwater-Quality Impacts 

The description of the affected environment in Section 2.3 serves as a baseline for the 

cumulative impacts assessments in this resource area. As described in Section 4.2, the 

impacts from NRC-authorized construction on groundwater quality would be SMALL, and no 

further mitigation would be warranted. As described in Section 5.2, the review team concludes 

that the impacts of operations on groundwater quality would also be SMALL, and no further 

mitigation would be warranted. 

The combined groundwater-quality impacts from construction and preconstruction of the 

proposed Units 3 and 4 are described in Section 4.2.3.2 and determined to be SMALL. In 

addition to the impacts from construction, preconstruction, and operations, the cumulative 

analysis also considers other past, present, and reasonably foreseeable future actions that 

could affect groundwater quality, including potential effects of GCC. For this analysis, two 

geographic areas of interest have been identified. For the Shallow Aquifer, which would be 

impacted by MCR seepage and potential spills, the geographic area of interest extends from 

recharge areas in Matagorda County to downgradient discharge areas along the Colorado 

River. For the Deep Aquifer the geographic area of interest extends from recharge areas in 

Wharton County to Matagorda Bay. 

Historically, the naturally occurring salinity of the Shallow Aquifer has limited its use. The 

primary groundwater quality concern in the Deep Aquifer has been the intrusion or 

encroachment of saltwater into the aquifer due to the withdrawal of groundwater for rice 

irrigation and other uses. 

As described in Sections 2.3.3.2 and 5.2.3.2, the MCR is connected hydraulically to the 

underlying Upper Shallow Aquifer and water from the MCR seeps into the aquifer. Groundwater 

plumes with the MCR as their source would be local to the STP site and the region immediately 

downgradient of the site to the Colorado River. Impacts from radioactive contaminants in the 

MCR and seepage from the MCR would be minimal as described in Sections 5.9.2.1 and 5.9.6. 

Total dissolved solids (TDS) are an indicator for nonradioactive contaminants, as described in 

Sections 2.3.3.2 and 5.2.3.2, and it is anticipated that the impacts from MCR seepage into the 

Upper Shallow Aquifer from Units 3 and 4 would be minimal. STP’s estimate of the median 

TDS during operation of the MCR for the existing units is approximately 2000 mg/L, and the 

estimate for operations of the existing and proposed units is approximately 3000 mg/L 

(Section 5.2.3.1). Groundwater from the Shallow Aquifer is currently described as slightly saline 
Cumulative Impacts 

February 2011 7-21 NUREG-1937 

(i.e., having TDS between 1000 and 3000 mg/L) (STPNOC 2010a, b) and is used locally to 

water livestock. It is not considered a source of fresh drinking water. While the operation of 

four units is projected to result in a higher concentration of TDS in MCR waters than current 

levels in the Upper Shallow Aquifer, the groundwater should still be within the range of slightly 

saline waters. Furthermore, the potential for dispersion would reduce the TDS concentration in 

the aquifer. The review team concludes that the impact to groundwater quality from MCR 

seepage into the Shallow Aquifer would be minimal. 

Potential offsite impact from saltwater intrusion or encroachment in the Deep Aquifer was 

assessed by the review team based on prior evaluation by the USGS (Ryder and Ardis 2002) 

and the design of production wells proposed by STP compared to groundwater well designs 

evaluated by the LCRA (2007). Ryder and Ardis (2002) described saltwater intrusion or 

encroachment as a potential threat to the rice-irrigation region, including Matagorda County. 

Because of the reduction of hydraulic head from long-term pumping of the aquifer system for 

rice irrigation, saltwater encroachment could occur by either lateral migration in coastal areas or 

vertical migration where freshwater sands overlie saline groundwater. However, Ryder and 

Ardis (2002) conclude that “(s)altwater encroachment is not currently a serious threat to the 

quality of groundwater used in the coastal rice-irrigation area” that includes portions of Wharton 

and Matagorda Counties. 

Production wells at the STP site are completed in the upper portion of the Deep Aquifer with up 

to 500 ft of screen and well bottoms at between 600 and 700 ft below ground surface (BGS). 

These wells are designed to be pumped at between 200 and 500 gpm. At the STP site, 

thickness of the fresh water aquifer is defined by the water quality, and it is believed to be 

somewhat greater than 1000-ft thick. Thus, a well completed in the Deep Aquifer to 700 ft BGS 

is more than 300 ft above the interface between fresh and saline groundwater. Based on its 

review of the LCRA study of pumping in a variable density aquifer system (LCRA 2007) (also 

see Section 2.3.3.2), the design parameters and pumping rates evaluated therein, and use of 

reasonable spacing between wells owned by the same permit holder, the review team 

concludes that the planned STP well design and pumping rate is appropriate and would 

minimize the potential for lateral or vertical saltwater intrusion. Furthermore, the LCRA study 

provides guidance to ensure that groundwater withdrawals do not result in significant 

degradation of the groundwater quality in the regional aquifer system (LCRA 2007). As such, 

the production wells at the STP site would not significantly impact the Deep Aquifer. 

Based on the regional evaluation by the USGS (Ryder and Ardis 2002) that analyzes current 

and future impacts to groundwater flow and related saltwater intrusion issues, the comparison of 

the well design used and proposed for future use at the STP site against the LCRA study results 

for the Deep Aquifer (LCRA 2007), and efforts by regional agencies including the LCRA and 

CPGCD to ensure groundwater quality in the future, the review team concludes the cumulative 

pumping rate to be used to support the operation of all four STP units does not pose a 
Cumulative Impacts 

NUREG-1937 7-22 February 2011 

substantial risk of salt water intrusion or encroachment for Matagorda County. As listed in 

Section 7.2.1.2, projects in the geographic area of interest that use the Deep Aquifer 

groundwater resource in the vicinity of the proposed new units are at least 3 to 4 miles from the 

STP site. These groundwater users utilize the groundwater resource, as does STPNOC, under 

the rules of the CPGCD (2009). Because the purpose of the CPGCD rules is to provide for the 

conserving, preserving, protecting, and recharging of the groundwater resource to control 

subsidence and prevent the waste and pollution of the groundwater resource, the review team 

concludes that potential impacts on the quality (e.g., saltwater intrusion or encroachment) of the 

Deep Aquifer from other users would be minimal, and are relatively distant from the STP site. 

Effects on Deep Aquifer groundwater quality from STP actions, as described above, would be 

local to the site and minimal. Regarding the Shallow Aquifer, the review team also concludes 

that seepage from the MCR from operation of all four STP units to groundwater would not result 

in a change in the characterization of the Upper Shallow Aquifer from its current characterization 

as a slightly saline water resource. Therefore, after reviewing other past, present, and 

reasonably foreseeable future projects in the vicinity of the STP site, the review team concludes 

that cumulative impacts to groundwater quality would be SMALL, and no further mitigation 

beyond that described in Chapters 4 and 5 would be warranted. 

Projected changes in the climate for the region during the life of the proposed Units 3 and 4 

include an increase in average temperature and a decrease in precipitation. These changes are 

likely to result in changes to agriculture including crops, pests, and the associated changes in 

application of nutrients, pesticides and herbicides that may reach groundwater. As a result, 

groundwater quality may be altered by the infiltration of different chemicals. While the

groundwater quality changes that are indirectly attributable to climate change may not be 

insignificant nationally or globally, the review team did not identify anything that would alter its 

conclusion regarding local groundwater quality above. 

7.3 Ecology 

This section addresses the cumulative impacts on terrestrial, wetlands and aquatic ecological 

resources as a result of activities associated with the proposed new units at the STP site and 

other past, present, and reasonably foreseeable future activities within the geographic area of 

interest for each resource. 

7.3.1 Terrestrial and Wetland Ecosystem Impacts 

The description of the affected environment in Section 2.4.1 provides the baseline for the 

cumulative impacts assessments for terrestrial and wetlands ecological resources. As 

described in Section 4.3.1, the review team concludes that the impacts from NRC-authorized 

construction on terrestrial and wetlands ecology would be SMALL, and no further mitigation 

would be warranted. The combined impacts of construction and preconstruction were described 
Cumulative Impacts 

February 2011 7-23 NUREG-1937 

in Section 4.3.1 and determined to be SMALL. As described in Section 5.3.1, the review team 

concludes that the impacts of operations on terrestrial and wetlands ecology would also be 

SMALL, and no further mitigation would be warranted. 

In addition to impacts from construction, preconstruction, and operation, the cumulative analysis 

also considers other past, present, and reasonably foreseeable future projects that could affect 

terrestrial ecological resources. For the cumulative analysis of potential impacts to terrestrial 

and wetland resources, the geographic area of interest includes the intersection of the Western 

Gulf Coast Plains ecoregion with the Matagorda Bay Watershed and the Lower Colorado River 

watershed (Figure 7-1). This area is expected to encompass the ecologically relevant 

landscape features and species. The geographic area of interest currently consists of primarily 

agricultural croplands with some rangelands. It also includes two wildlife refuges: the Clive 

Runnells Family Mad Island Marsh Preserve, and the Mad Island Wildlife Management Area, 

which is managed by TPWD. 

7.3.1.1 Wildlife and Plant Communities 

The STP site is located within coastal prairies of the Western Gulf Coast Plains ecoregion 

(Griffith et al. 2004). Coastal prairies of the Western Gulf Coast Plains are tallgrass prairies 

similar to the tallgrass prairie of the Midwestern United States (Allain et al. 1999), with 

vegetation consisting mostly of grasses overlain by a diverse variety of wildflowers and other 

plants. These prairies are estimated to have historically covered about 6.5 million ac of Texas. 

During the past century, the Texas coast has experienced considerable urban, industrial, and 

agricultural growth that fragmented lands, converted prairies, changed river flows, decreased 

water quality, and increased sediment loads and pollutants on marshes and estuaries. 

Projections indicate continued high growth and increasing fragmentation in most parts of this 

ecoregion (TPWD 2009c). Less than 1 percent of the original native grasslands of the entire 

coastal prairie in Texas are estimated to remain in a relatively pristine state (Diamond and 

Smeins 1984). In the late 1800s, large numbers of cattle were introduced onto Southwest 

grasslands and livestock numbers remained high through the 1920s. Livestock grazing and 

ranching continue to be large components of land use in the region, but the majority of the land 

has been altered for growing rice, sugarcane, forage, and grain crops. 

The Texas Gulf Coast historically contained abundant and diverse wetlands, but thousands of 

acres of wetlands have been lost during the past century to agricultural land use and 

development. Approximately 30 percent of the coastal prairies along the Texas Gulf coast were 

once wetlands (TPWD 2010). Human activities, including landscape alteration for agricultural, 

industrial or urban uses, continue to significantly threaten remaining wetland habitats (TPWD 

2005). Of the estimated 4,105,343 ac of coastal Texas wetlands existing in 1955, only 

3,894,753 ac of wetlands were estimated to remain in 1992 (Moulton et al. 1997). Suburban 

and industrial development are reducing wetland habitat at a faster rate than anywhere else 

along the coast. In addition, decreased precipitation, sea-level rise, more frequent storm 
Cumulative Impacts 

NUREG-1937 7-24 February 2011 

Figure 7-1. Geographic Area of Interest Evaluated to Assess Cumulative Impacts to 

Terrestrial Ecological Resources
Cumulative Impacts 

February 2011 7-25 NUREG-1937 

surges, increased intensity of coastal storms, and increased temperatures resulting from GCC 

could potentially also contribute to wetland losses and exacerbate the ongoing trend 

(GCRP 2009). Rice fields, prairie wetlands, and coastal marshes associated with the coastal 

prairie provide important habitat for waterfowl and thousands of other forms of wildlife. TPWD 

identifies the Gulf coast and associated grassland prairies, wetlands, marshes, and agriculture 

as one of the most important wintering areas for North America’s waterfowl populations 

(TPWD 2005). 

Past actions in the geographic area of interest include the development of STP Units 1 and 2, 

which required building and filling the 7000-ac MCR, and building the existing facilities 

associated with STP Units 1 and 2 that comprise about 300 acres. Other past projects in the 

geographic area of interest that have contributed to loss of available habitat include the building 

and operation of various industrial facilities and wastewater treatment plants (Table 7-1). These 

include the Formosa Plastics Corporation plant, the Texas Liquid Fertilizer Company, and the 

Alcoa aluminum plant near Point Comfort, Texas; and Equistar Chemical LP’s Matagorda facility 

and OXEA Corporation’s chemical plant near Bay City, Texas. Building and development of 

these industrial areas likely contributed to loss of agricultural lands and rangelands that would 

have provided habitat for generalist species including game species. Development of industrial 

plants near the Gulf coast contributed to loss of wetland habitats. 

Building the proposed Units 3 and 4 at STP would affect limited areas of several habitat types 

including the permanent loss of approximately 300 ac, consisting mostly of maintained and 

mowed grasslands, shrub-scrub habitat, and existing industrial areas. Overall, 540 ac would be 

disturbed during preconstruction and construction, which represent about 4 percent of the total 

site. No native coastal prairie habitat or wetland habitats would be affected by construction and 

preconstruction activities for the proposed new reactors at the STP site. Proposed future 

actions within the geographic area of interest that would adversely affect terrestrial resources in 

a similar way to development at the STP site include the proposed development and building of 

energy projects including the WSEC (located on a 1200-ac tract of land approximately 5 mi 

northeast of the STP site), Calhoun LNG Terminal on Matagorda Bay, Victoria County Station, 

upgrades to the E.S. Joslin Power Plant Project, and the Mary Rhodes Pipeline Phase II project 

(Table 7-1). Other future actions or conditions that would contribute to cumulative effects on 

terrestrial resources would include creation and/or upgrading transmission lines, expansion of 

existing roads and development of new roads, continued industrial and urban development 

throughout the geographic area of interest, increased outdoor recreation, nonpoint source runoff 

from activities such as agriculture and ranching, and GCC. 

Development of the WSEC would potentially result in the loss of wildlife habitat. Activities 

associated with this facility that could cumulatively affect terrestrial ecological resources include 

land clearing and grading (temporary and permanent), filling and/or draining of wetlands, 

population growth due to building and operation, heavy equipment operation, traffic, noise, 
Cumulative Impacts 

NUREG-1937 7-26 February 2011 

avian collisions, and fugitive dust. The main site for the Victoria County Station lies outside the 

area of analysis for cumulative effects to terrestrial resources, but infrastructure planned to 

support the proposed units would include new rights-of-way and corridors for water pipelines 

and transmission lines that would potentially have portions in the area of interest. 

Upgrading the E.S. Joslin power plant would likely also contribute to cumulative effects to 

terrestrial resources by increasing noise levels and increased traffic, but would be expected to 

affect a smaller area. Site preparation and building activities for these proposed projects would 

likely displace or destroy wildlife that inhabit areas where activities take place. Some wildlife, 

including important species, would perish or be displaced during land clearing for any of the 

above projects as a consequence of direct mortality, habitat loss, habitat fragmentation, and 

competition for remaining resources. Less mobile animals, such as reptiles, amphibians, and 

small mammals, would be at greater risk of incurring mortality than more mobile animals, such 

as birds, many of which would be displaced to adjacent communities. Undisturbed land 

adjacent to areas of activity could provide habitat to support displaced wildlife, but increased 

competition for available space and resources could affect population levels. Such landdisturbing activities are not expected to destabilize any terrestrial resources; however site 

preparation and building activities for other projects could noticeably alter important attributes of 

terrestrial resources. Wildlife would also be subjected to impacts from noise and traffic, and 

birds could be injured or suffer mortality through collisions with tall structures or equipment. The 

impact on wildlife from each noise-generating activity is expected to be temporary and minor. 

Because only existing transmission line corridors would be used to support power transmission 

from proposed Units 3 and 4 at STP, there would be no additional habitat loss associated with 

building new transmission corridors. Development of the WSEC and the Victoria County Station 

nuclear facility would potentially require new transmission corridors to be created. The creation 

of new transmission line corridors could be beneficial for some species, including those that 

inhabit early successional habitat or use edge environments, such as white-tailed deer 

(Odocoileus virginianus), or bobwhite quail (Colinus virginianus). However, in general, new 

transmission lines and corridors would also present increased risks for avian collision and 

electrocution, and would contribute to habitat fragmentation. The maintenance of transmissionline corridors could also be beneficial for some species, including those that inhabit early 

successional habitat or use edge environments. Vegetation maintenance and control along the 

corridors would not be anticipated to cause any increases in bird collisions and electrocutions, 

and thus, would not be expected to increase and contribute to cumulative effects. Much of the 

land in the geographic area of interest consists of agricultural cropland and rangelands, and the 

relative amounts of forested habitat crossed by new corridors would likely be small. 

Development of the proposed Mary Rhodes Pipeline Phase II project would likely also 

contribute to regional habitat loss and fragmentation within the region. Potential cumulative 

impacts to terrestrial resources from construction and operation of the proposed water transport 
Cumulative Impacts 

February 2011 7-27 NUREG-1937 

line would be similar to the impacts resulting from constructing and maintaining new 

transmission corridors including increased habitat fragmentation, and creation of early 

successional habitat that may benefit certain species. Impacts to terrestrial species during 

construction of the pipeline (e.g., increased noise and traffic, displacement of certain wildlife 

species, limited mortality and injuries to wildlife) would be temporary. 

The review team estimates that maximum salt deposition from cooling tower drift under normal 

operations for STP Units 3 and 4 would occur on the site; however, damage to vegetation and 

habitats would be minimal and would not contribute to a cumulative salt drift outside the STP 

boundaries (Figure 5.3-1 in STPNOC 2010a). There are no cooling towers associated with STP 

Units 1 and 2. Cooling towers for other proposed energy projects in the geographic area of 

interest are sufficiently distant from the proposed site such that the effects on terrestrial 

resources would not be additive or synergistic. Cooling tower plumes are not expected to 

overlap or result in cumulative salt deposition, and potential fogging and icing would not 

noticeably affect terrestrial resources. 

The geographic area of interest lies within the Central Flyway migration route which is a major 

migratory corridor for neo-tropical migrants and other birds. Mechanical draft cooling towers 

planned for the proposed units at STP are approximately of similar height (119 ft above grade) 

as existing buildings at the site and would not be expected to present a significant collision 

hazard for migratory birds. Cooling towers or tall structures associated with other proposed 

energy projects or with the Calhoun LNG terminal may present increased risks of collision and 

increased mortality. Although bird mortality from collisions with tall structures has been 

documented, it would not be expected to be a significant source of mortality and would have a 

minimal effect on populations. 

The habitats that would be disturbed at the STP site are common on the 12,220-ac property, 

and no habitats that would be lost to building the proposed new units are considered to be 

critical or important habitat for the survival of important species or common wildlife. Major 

portions of the STP site were previously used for agricultural and grazing purposes and the site 

consists of primarily of successional habitats. Development of proposed projects such as 

transmission lines for the Victoria County Station and the WSEC would most likely affect 

rangeland and agricultural habitats but would not likely affect substantial amounts of prairies or 

bottomland forest habitats. Because the majority of the Gulf coast prairies and forests have 

been subject to agricultural development and livestock grazing, future development, and 

proposed actions would likely further reduce these types of habitats and may also affect 

wetlands within the region, noticeably altering these terrestrial resources. 

7.3.1.2 Important Species 

Future urban and industrial development, new transmission corridors, and the effects of GCC 

may potentially affect important species in the geographic area of interest primarily by 
Cumulative Impacts 

NUREG-1937 7-28 February 2011 

decreasing or degrading the available habitat for these species. Habitat loss may occur through 

proposed projects that cause permanent loss of upland and wetland habitats, sea level rise, 

increasing salinity of estuarine areas, and inundation or filling of wetland habitats. Sea level rise 

resulting from climate change along the Gulf coast of Texas would accelerate loss of wetlands 

and estuaries, thus eliminating breeding and foraging habitat for commercial, game, and 

threatened and endangered species (Ning et al. 2003; GCRP 2009). GCC could also cause 

shifts in species ranges and migratory corridors as well as changes in ecological processes 

(GCRP 2009). Impacts from development, new transmission corridors, and potential effects of 

GCC would noticeably alter, but not destabilize, important species in the geographic area of 

interest. 

Populations of three species of birds listed under the Endangered Species Act (ESA) occur 

along the Gulf Coast adjacent to the geographic area of interest for cumulative effects. The 

Federally endangered whooping crane (Grus americana) and the Federally threatened piping 

plover (Charadrius melodus) overwinter along the Gulf coast. The major threats to these two 

species would be decreased or degraded foraging habitat as a result of sea level rise and 

increased salinity caused by climate change that may change prey availability for the whooping 

crane. The Federally endangered northern Aplomado falcon (Falco femoralis septentrionalis) 

also occurs within the geographic area of interest and nests on Matagorda Island. The major 

threat to this species would be the loss of hunting and foraging habitat to development. In 

addition, building new transmission lines and corridors would also present increased risks for 

avian collision and electrocution for all of these species and would contribute to habitat 

fragmentation. Structures and transmission lines associated with future projects could also 

present increased threats of collision and electrocution within the migratory path for trans-Gulf 

migratory birds. 

The American alligator (Alligator mississippiensis), listed as threatened under the ESA (due to 

similarity of appearance to the American crocodile [Crocodylus acutus]) is found in the 

geographic area of interest, but is considered to have fully recovered (52 FR 21059). Although 

trends and conditions, such as urbanization, industrialization, and GCC, could affect the 

American alligator’s habitat and local distribution, none of the identified present or future 

projects are expected to affect the recovered species. 

Eight species of birds are listed as threatened or endangered by the State of Texas in 

Matagorda County. Three species listed as threatened are raptors: the bald eagle 

(Haliaeetus leucocephalus); the peregrine falcon (Falco peregrinus); and the white-tailed hawk 

(Buteo albicaudatus). Proposed projects that reduce available hunting/foraging habitat or 

involve construction of new transmission lines and corridors would potentially cause adverse 

effects to these species. Three of the state-listed species are wading birds, the white-faced ibis 

(Plegadis chihi), reddish egret (Egretta rufescens), and the woodstork, (Mycteria americana). 

Activities that alter or destroy wetland and marsh habitats where birds forage would adversely 
Cumulative Impacts 

February 2011 7-29 NUREG-1937 

affect these species. These birds would also be subject to increased risk of mortality through 

collision and electrocution from transmission lines or collision with tall structures. The brown 

pelican (Pelecanus occidentalis) is listed as endangered in Texas and occurs within the analysis 

area. This species would also suffer increased risk of mortality from collision or electrocution 

with transmission lines or collision with tall structures. Nesting habitat for the brown pelican 

along the Gulf coast might be altered or inundated by sea level rise due to changing climate. 

The sooty tern (Sterna fuscata) is a pelagic species that is found across tropical oceans and is 

unlikely to use habitats within the area of interest. 

State-listed reptile species including the smooth green snake (Liochlorophis vernalis), the Texas 

scarlet snake (Cemophora coccinea lineri), the Texas tortoise (Gopherus berlandieri), Texas 

horned lizard (Phrynosoma cornutum), and timber rattlesnake (Crotalus horridus) would be 

affected by projects involving land clearing, habitat fragmentation or loss, and increased vehicle 

traffic on roads and right-of-ways. These species would be displaced and would likely suffer 

increased mortality. 

The creation and maintenance of transmission line or water pipeline corridors could be 

beneficial for some important species, including those that inhabit early successional habitat or 

use edge environments, such as white-tailed deer (Odocoileus virginianus), or bobwhite quail 

(Colinus virginianus). Local populations of game species may be temporarily affected by 

regional development activities. Because many game species are generalists, they potentially 

occur across a variety of habitats within the area of interest. During land-clearing activities, 

habitat for game species may be lost, and wildlife would be displaced during the site preparation 

and building activities. 

Summary 

Cumulative impacts to terrestrial ecology resources are estimated based on the information 

provided by STPNOC and the review team’s independent evaluation. Past, present, and 

reasonably foreseeable future activities exist in the geographic area of interest that could affect 

terrestrial ecological resources. Development of new transmission corridors and infrastructure 

to support the proposed future projects would likely affect wildlife and may be detrimental to 

wetland and bottomland habitats. Loss of wildlife habitat, increased fragmentation, and 

increased loss of wetlands from continued development and climate change are unavoidable 

and would continue to occur. The extents of habitats for most important species are relatively 

limited, and limited native coastal prairie and wetland habitats remain in the area of interest. 

Detectable alteration of habitat, loss of habitat, increased habitat fragmentation, and increased 

risk of collision and electrocution within the Central Migratory Corridor would contribute to the 

cumulative impacts. Based on this analysis, the review team concludes that cumulative impacts 

from past, present, and reasonably foreseeable future actions on important species and habitat 

loss in the Western Gulf Coast Plains near the STP site would noticeably alter, but would not 

likely destabilize, the terrestrial ecological resources. The review team concludes that the 
Cumulative Impacts 

NUREG-1937 7-30 February 2011 

cumulative impacts from construction, preconstruction, and operations of Units 3 and 4 and from 

past, present, and reasonably foreseeable future actions to terrestrial resources in the region of 

interest would be MODERATE; however, the incremental contribution of impacts to terrestrial 

resources from NRC-authorized activities at the STP site would be SMALL. 

7.3.2 Aquatic Ecosystem Impacts 

The description of the affected environment in Section 2.4.2 provides the baseline for the 

cumulative impacts assessment for aquatic ecological resources. As described in Section 4.3.2, 

the NRC staff concludes that the impacts of NRC-authorized construction activities on aquatic 

biota would be SMALL. The combined impacts from construction and preconstruction, including 

the upgrades to the Hillje transmission corridor, were also described in Section 4.3.2 and were 

determined to be SMALL by the review team. As described in Section 5.3.2, the review team 

concludes that the impacts on the aquatic resources in onsite water bodies from the operation of 

proposed Units 3 and 4, in the Colorado River from operation of the RMPF and the discharge 

structure, and in offsite water bodies from maintenance and operation of transmission lines and 

corridors would be SMALL. 

In addition to the impacts from construction, preconstruction, and operation of the proposed 

STP Units 3 and 4 and associated transmission lines and corridors, this cumulative analysis 

also considers other past, present, and reasonably foreseeable future actions that could affect 

aquatic ecology. For this cumulative analysis, the geographic area of interest is based on the 

extent of the aquatic community within the influence of the STP site. The area encompasses 

the lower Colorado River Basin and Matagorda Bay, including the GIWW between Matagorda 

Bay and the northeastern Colorado River lock (Figures 2-8 and 2-21 in Chapter 2). 

The aquatic resources of the lower Colorado River Basin have been affected by development 

and changes to the mouth of the river and its confluence with the Gulf of Mexico since the 

1920s. As discussed in Section 2.4.2.1, the course of the river has been redirected by various 

construction projects into the Gulf of Mexico, and the most recent change diverted the river into 

Matagorda Bay in 1992. These alterations have affected the aquatic resources by changing the 

inputs of freshwater and estuarine waters into the lower Colorado River and the area available 

for aquatic organisms to navigate through the river, bay, and Gulf. The increase in freshwater to 

the bay has resulted in a slight decrease in salinity and increased marsh areas that could 

become nursery areas for numerous commercially and recreationally important fish and 

shellfish. There has not been a significant change in Eastern oyster (Crassostrea virginica) and 

finfish catch per unit effort (CPUE) since the diversion channel opened into Matagorda Bay. 

However, white shrimp (Litopenaeus setiferus) CPUE has decreased, and brown shrimp 

(Farfantepenaeus aztecus) and blue crab (Callinectes sapidus) CPUEs have increased in the 

Bay (Wilber and Bass 1998; Corps 2007). Species richness and diversity have increased in the 

lower Colorado River (from the GIWW to navigation mile marker 8) based on surveys in 

2007-2008 compared to similar surveys in 1983-1884 (NRC 1986; STPNOC 2010a; 
Cumulative Impacts 

February 2011 7-31 NUREG-1937 

ENSR 2008). The apparent change in the aquatic community of the Colorado River in the 

vicinity of the site could be due to a number of reasons (e.g., differences in sampling protocol 

over time, variance in weather conditions during the two sampling efforts, a river diversion 

project, and sea level rise). However, the shift in the aquatic community is not likely to be 

associated with the construction and operation of the RMPF, barge slip, or discharge structure 

for existing Units 1 and 2 because those activities were primarily on the shoreline of the river 

and used erosion and turbidity controls (e.g., sheet pile walls). While slow-moving benthic 

organisms (e.g., mollusks and polychaetes) were lost during construction, these organisms 

likely recolonized the area. Other mobile aquatic organisms likely avoided the area during 

construction and returned after sheet pile walls and other in-stream activities were completed. 

In addition, during the construction of the MCR for STP Units 1 and 2, the onsite water body, 

Little Robbins Slough, was diverted around the reservoir. The diversion temporarily changed 

the flow of freshwater into wetlands to the south of the site as well as flows into the Clive 

Runnells Family Mad Island Marsh Preserve and the Mad Island Wildlife Management Area. 

However, studies conducted in the 1980s showed that the changes in freshwater input to the 

preserve and management areas were minimal (NRC 1986). 

The construction and filling of the MCR created a new water resource onsite. The first aquatic 

surveys of the MCR were completed in 2007 through 2008, and the results were discussed in 

Section 2.4.2.1. The results demonstrated that a diverse aquatic community had developed as 

fish and invertebrates were entrained in water pumped from the Colorado River. The MCR is 

not considered waters of the U.S. or the State, access to the MCR by the public is prohibited 

and the aquatic resources are not harvested. 

Construction of STP Units 1 and 2 caused minor, temporary changes in the aquatic community 

adjacent to facilities on the Colorado River (NRC 1986). Cofferdams were used to minimize the 

impacts from erosion and turbidity in the river during installation of the RMPF and barge slip. 

Upon the cessation of construction activities for Units 1 and 2 in the Colorado River, aquatic 

habitat recolonized that area as demonstrated by the diverse aquatic community in the vicinity 

that was evaluated during the 1983, 1984, and 2007-2008 surveys (NRC 1986; ENSR 2008; 

STPNOC 2010a). Installation of the discharge pipes and stabilization of the river bank created 

temporary changes to the aquatic community, similar to the construction of the RMPF. 

Additionally, the review team considered the potential cumulative impacts of operating four units 

at the STP site, and the additional requirement of makeup water to be pumped from the RMPF. 

Past studies on aquatic organisms in the Colorado River that are likely to be impinged or 

entrained at the RMPF concluded that impacts to the important species would be insignificant 

and minor, primarily because the density of organisms in the vicinity is rather low and the 

species are ubiquitous in the region (NRC 1986; STPNOC 2010a). The increase in species 

richness and diversity in the Colorado River from 1983-1984 to 2007-2008 indicates that the 

operation of the RMPF has had negligible impact on the aquatic community in the vicinity of the 
Cumulative Impacts 

NUREG-1937 7-32 February 2011 

site although impingement, entrainment, and entrapment at the RMPF have not been evaluated 

since 1984 (NRC 1986; STPNOC 2010a; ENSR 2008). The types of aquatic organisms 

currently within the vicinity of the site are common species, and no threatened or endangered 

species have been found. Additionally, the structure and operation of the RMPF are designed 

to minimize impacts on aquatic biota. Therefore, impacts from operation of the RMPF 

(impingement, entrainment, and entrapment) for four units are likely to remain minimal. 

STPNOC plans on increasing the water level in the MCR and that would result in additional 

seepage to groundwater and the relief well system that could contribute flow to Little Robbins 

Slough and the wetlands to the south of the site (STPNOC 2010a). The increase in facilities 

and structures like parking lots would change the flow of stormwater into the drainages onsite. 

STPNOC plans on moving and constructing additional drainages and culverts to manage the 

flows after precipitation events (STPNOC 2010a). A site-specific stormwater pollution 

prevention plan would include practices for minimizing impacts to the aquatic communities in 

these onsite drainages. Operation of the four units would affect the aquatic community in the 

MCR. The two operating circulating water intake structures (CWISs) would increase 

entrainment and impingement of the aquatic community. The two discharges from the four units 

would increase the water temperature in the MCR. Aquatic organisms in the MCR would either 

avoid or acclimate to the new conditions. However, since the aquatic community in the MCR is 

isolated from the onsite waterbodies and the Colorado River, these impacts are negligible to the 

overall aquatic resources of the geographic area of interest. 

The review team also considered the potential cumulative impacts related to thermal and 

chemical discharges. There have been no past impacts from discharges into the Colorado 

River because STPNOC has not released water from the MCR into the river except for one test 

of the discharge facility in 1997 (STPNOC 2010a). As discussed in Sections 5.2.3.1 and 

5.3.2.1, the frequency and duration of discharge from the MCR into the Colorado River would be 

managed by STPNOC based on water quality in the MCR and TPDES permit conditions. The 

operation of four units would change the water quality in the MCR (Table 5-3). Chemical 

releases from discharging the MCR into the Colorado River are expected to be below the 

criteria for protection of aquatic life (TCEQ 2005). Physical impacts (e.g., scouring of aquatic 

habitat) are likely to be minimal due to the flow and frequency of discharge. In general, these 

impacts would not noticeably alter the resource. However, under certain conditions, the size 

and configuration of the thermal plume from the discharge of MCR water into the river from the 

operation of four units in combination with poor river water quality could impede passage of the 

aquatic organisms in the Colorado River, including species that are of commercial and 

recreational importance and species that are Federally managed and have designated essential 

fish habitat. However, the foraging behavior and high fecundity of the aquatic organisms 

indicate that the effects from the thermal plume would not noticeably alter or destabilize the 

populations or aquatic community in the lower Colorado River. 
Cumulative Impacts 

February 2011 7-33 NUREG-1937 

Several activities associated with maintenance of the shoreline as well as dredging to maintain 

the RMPF and barge slip are planned for Units 1 and 2 and would continue for all four units. 

The revetment along 1600 ft of shoreline on the west bank of the Colorado River, beginning at 

the MCR spillway and extending down the river to the STP site property line, has become 

damaged due to bank erosion during and following high river flows. Flooding has eroded and 

undercut the revetment and damaged the associated rigid matting. STPNOC has requested 

approval from the Corps to conduct restoration work as part of the existing permit with the Corps 

or under the Nationwide Permit No. 13 for bank stabilization activities (STPNOC 2010a). 

Aquatic organisms inhabiting the shoreline habitat would be disturbed during restoration 

activities, but these impacts would be temporary and the organisms would likely recolonize the 

area. 

In addition to the maintenance dredging in the Colorado River described in Chapter 5, the Corps 

would continue dredging operations in the Colorado River to maintain the navigation channel. 

Dredging would remove benthic habitat and the organisms that are not highly mobile (e.g., 

mollusks). Organisms that can readily swim would likely avoid the area during dredging 

activities. After dredging activities, these areas would be re-colonized by the aquatic 

community. Impacts from dredging on aquatic organisms would be minor. 

Future projects in the vicinity of the STP site would use significant quantities of Colorado River 

flow, which could affect aquatic habitat and migratory behavior. These projects include the 

proposed LCRA-SAWS project, WSEC, and the proposed Mary Rhodes Pipeline Phase II 

project (TWDB 2006a). The LCRA-SAWS project is projected to generate 150,000 ac-ft of new 

water supplies by 2060 through conjunctive use of groundwater from the Gulf Coast Aquifer and 

surface water supplies from the Colorado River (TWDB 2006a). A habitat assessment program 

is underway to collect baseline information and evaluate effects of freshwater inflow alterations 

to Matagorda Bay as part of the LCRA-SAWS project (LCRA-SAWS 2006). LCRA has 

evaluated WSEC in its Water Supply Resource Plan for Region K, Matagorda County. The 

increases in water demand from 2010 to 2020 is approximately 22,000 ac-ft per year, which 

would be attributed to the needs for WSEC (LCRA 2008). As discussed in Section 7.2.1.1, the 

City of Corpus Christi may build Phase II of the Mary Rhodes Pipeline from Bay City to Lake 

Texana (City of Corpus Christi 2009). Final details on these projects and their potential impacts 

on aquatic resources have not been completed; however, these projects have the potential to 

change the freshwater contribution in the river within the vicinity of STP. Changes in saltwater 

intrusion or flow of salt water into the river could change the habitat, movement, and 

composition of the aquatic community in the vicinity. These types of changes are likely to have 

influenced the shift in aquatic communities as demonstrated by the differences observed in 

earlier studies with varying flow conditions in the river (NRC 1975, 1986), as well as in the shifts 

observed by comparing the results of the studies before and after the completion of the 

diversion of the river into Matagorda Bay in 1992 (ENSR 2008). 
Cumulative Impacts 

NUREG-1937 7-34 February 2011 

Proposed future power generation facilities, including WSEC and the Victoria County Station, 

may require the development of new transmission systems (lines as well as corridors) in the 

geographic area of interest. The WSEC may be required to add additional transmission 

capabilities within the vicinity for its power transmission, but that information is currently not 

available to evaluate. If new transmission corridors are built, they would likely have a minor 

effect on aquatic species assuming transmission line routing considers aquatic resources and 

best management practices (BMPs) are employed during construction and during transmission 

line maintenance activities once the lines are completed and energized. Because only existing 

transmission corridors would be used to support power transmission from proposed Units 3 and 

4, there would be no additional impacts to aquatic resources associated with construction of 

new transmission corridors for the proposed new STP units. Vegetation maintenance and 

control along existing and future corridors would not be expected to increase and contribute to 

cumulative effects (STPNOC 2010a). 

Anthropogenic (derived from human activities) stressors such as residential or industrial 

development in the vicinity of STP site can affect aquatic resources. Increased urbanization 

and population growth, while projected to be low in comparison to other locations in Texas 

(Table 2-17), would still lead to increased development along the shores of the Colorado River 

that can contribute to cumulative impacts in the lower Colorado River Basin through habitat loss 

and nonpoint source pollution. Future activities could lead to increased water needs, nonpoint 

and point source water pollution, vessel traffic on the waterways, maintenance dredging, and 

fishing pressures. 

Commercial and recreational fishing in the Colorado River and Matagorda Bay would likely 

continue to increase in the future. The region is recognized for recreational fishing of a number 

of species, and fishing would likely increase with increased urbanization in the vicinity. 

Matagorda Bay is one of the recognized regions in Texas for commercial fishing, primarily 

associated with the shrimp industry (TPWD 2002), although these fisheries are not significant 

contributors to employment in the region (Section 2.5.2). In efforts to improve the fisheries in 

the area, TPWD has designated the “most eastern half of the eastern arm of Matagorda Bay” as 

a finfish and shellfish nursery, closing the area to commercial fishing and commercial harvesting 

of oysters (LCRA et al. 2006). A freshwater inflow needs study for Matagorda Bay has identified 

several alternatives associated with water management strategies designed to improve 

commercial fishing opportunities (LCRA et al. 2006). If management strategies do not improve 

sustainability of fisheries, then increased fishing pressures could result in overall decreased 

biological productivity for the Colorado River and Matagorda Bay. 

In addition to direct anthropogenic activities, GCC could impose additional stressors on aquatic 

communities. The presence of natural environmental stressors (e.g., short- or long-term 

changes in precipitation or temperature) would contribute to the cumulative environmental 

impacts to the Colorado River and Matagorda Bay. GCC could lead to decreased precipitation, 
Cumulative Impacts 

February 2011 7-35 NUREG-1937 

increased sea levels, varying freshwater inflow, increased temperatures, increased storm 

surges, greater intensity of coastal storms, and increased nonpoint source pollution from runoff 

during these storms, in the water bodies in the geographic area of interest (Nielsen-Gammon 

1995; Montagna et al. 1995; GCRP 2009). Such changes could alter salinity, change 

freshwater inflow, and reduce dissolved oxygen, which could directly affect aquatic habitat. 

Rising sea water due to global climate change could affect water levels in the lower Colorado 

River and Matagorda Bay and subsequently change the water quality associated with the mixing 

of freshwater and estuarine waters (Montagna et al. 1995; GCRP 2009). Similarly, GCC could 

affect the water levels and water quality in the Clive Runnells Family Mad Island Marsh 

Preserve and the Mad Island Wildlife Management Area. These kinds of changes have been 

experienced in the vicinity of STP associated with the diversion of Little Robbins Slough during 

the construction of the MCR and with the diversion of the Colorado River into the Gulf and 

Matagorda Bay since the 1920s. As discussed in Section 2.4.2, the aquatic communities in the 

vicinity have shifted along with these water quality changes with time. Most recent studies on 

Matagorda Bay since the opening of the diversion channel from the Colorado River have shown 

slower than expected development of wetlands, oyster reefs, and other aquatic habitat (Wilber 

and Bass 1998; LCRA et al. 2006; Corps 2007). LCRA has indicated that more freshwater 

inflow into the Bay is needed to increase biological productivity in the bay (LCRA et al. 2006). 

The effects of rising sea level would likely be counterproductive to the current efforts to increase 

freshwater flows into the Bay. Changes in water quality in Matagorda Bay and the lower 

Colorado River could create areas that are hypoxic (low in dissolved oxygen) and lead to further 

stress on aquatic communities (Montagna et al. 1995). These stressors would result in shifts in 

species ranges, habitats, and migratory behaviors and also alter ecosystem processes (GCRP 

2009). 

Summary 

Cumulative impacts to aquatic ecology resources are estimated based on the information 

provided by STPNOC and the review team’s independent evaluation. Past, present and future 

activities exist in the geographic area of interest that could contribute to cumulative effects to 

aquatic ecological resources. Future development of industries that compete for water in the 

Colorado River as well as management of water budgets across the State of Texas through 

diversion projects like the LCRA-SAWS project and the Mary Rhodes Pipeline Phase II project 

would likely affect aquatic resources in the lower Colorado River. Under certain conditions, the 

thermal plume from the discharge of MCR water into the river could impede passage of aquatic 

organisms in the river. The alterations to the transmission corridors for Units 3 and 4 would 

have negligible effects on aquatic species in the area, and the cumulative impacts associated 

with transmission system upgrades on the aquatic community for other projects in the 

geographic area of interest would likely be minor. Direct and indirect anthropogenic and natural 

environmental stressors, including other energy projects, in the geographic area of interest 

would cumulatively lead to effects on the aquatic communities that would noticeably alter 
Cumulative Impacts 

NUREG-1937 7-36 February 2011 

important attributes, such as species range, habitat availability, ecosystem processes, migratory 

corridors and behavior, species diversity, and species abundance. The review team concludes 

that cumulative impacts from past, present, and reasonably foreseeable actions to aquatic 

resources in the geographic area of interest would be MODERATE. The incremental 

contribution of NRC-authorized construction and the operation of the proposed Units 3 and 4 to 

cumulative impacts on aquatic resources in onsite water bodies, the Colorado River, and 

Matagorda Bay would be SMALL. 

7.4 Socioeconomics and Environmental Justice 

The evaluation of cumulative impacts on socioeconomics and environmental justice is described 

in the following sections. 

7.4.1 Socioeconomics 

The description of the affected environment in Section 2.5 serves as a baseline for the 

cumulative impacts assessment in this resource area. As described in Section 4.4, any 

negative impacts of the NRC-authorized construction activities on socioeconomics would be 

SMALL and adverse, with the following exceptions. First, NRC-authorized construction would 

result in MODERATE beneficial economic and tax revenue impacts to Matagorda County, and 

SMALL beneficial economic and tax revenue impacts elsewhere in the region. Second, NRCauthorized construction (75 percent of the total project on a labor-hours basis) generally would 

result in MODERATE and adverse demographic impact and MODERATE adverse impacts in 

Matagorda County on roads, housing, and education and fire services. As described in 

Section 5.4, the adverse socioeconomic impacts of operations would be SMALL. Operations of 

proposed Units 3 and 4 would result in LARGE beneficial tax revenue impacts and MODERATE 

beneficial economic impacts on Matagorda County, and SMALL beneficial economic and tax 

revenue impacts elsewhere in the region. 

The combined impacts from construction and preconstruction were described in Section 4.4 and 

were determined to be the same as described above for NRC-authorized construction. In 

addition to the impacts from construction, preconstruction, and operations, the cumulative 

analysis also considers other past, present, and reasonably foreseeable future projects that 

could affect socioeconomics. For this analysis, the primary geographic area of interest is 

Matagorda and Brazoria Counties because these counties are the principal areas where STP 

workers would live, where the economy, tax base and infrastructure would most likely be 

affected, and therefore where socioeconomic impacts would occur. However, the geographic 

area of interest was modified as appropriate for specific impact analyses; for example, specific 

taxation jurisdictions were considered when appropriate, and Calhoun and Jackson Counties 

were considered for impacts of the Victoria County Station, Matagorda Ship Channel 

improvements, Calhoun LNG terminal, and E.S. Joslin Power Plant projects. 
Cumulative Impacts 

February 2011 7-37 NUREG-1937 

Matagorda County historically had an agricultural based economy initially centered on cattle, 

corn, and cotton, and later on rice. By the 1970s the county was a leading cattle producing 

area. Significant amounts of cotton, grain sorghums, soy beans, and corn were grown there, 

while rice remained a very important crop. Oil and gas fields were found early in the 20th

Century in Matagorda County and oil production grew until the mid-1960s, then began to 

decline. The County also has had several chemical and gas-processing and oil-refining 

facilities. STP Units 1 and 2 were constructed during the 1970s and 1980s and began 

operations in 1988 and 1989, respectively. Matagorda County population grew from about 

18,000 people in 1930 to about 37,000 in 1980, but remained almost constant at 37,000 

throughout the 1980s and 1990s. 

Agriculture was the foundation of the Brazoria County's early economy, and some of the State's 

largest and most prosperous sugar and cotton plantations were located there in the 19th century. 

Rice became the center of the agricultural economy after World War II. In the 1990s, there 

were about 41,000 acres used for rice production. Oil production began in 1902, sulfur was first 

mined in 1912, and oil and mining remain important. The Dow Chemical Company, drawn to 

natural resources at Freeport, came in 1939 and gave rise to the Brazosport industrial and port 

community, which subsequently included several chemical processing plants. By the 1980s the 

county had 186 manufacturing establishments that employed almost 18,000 workers. The 

population boomed and became more urbanized, with Brazoria County population rising from 

23,000 in 1930 to nearly 242,000 in the year 2000 (TSHA 2009a, b). 

The socioeconomic impact analyses in Chapters 4 and 5 are cumulative by nature and depend 

largely on the rate of change from existing conditions, for example, the increase in the rate of 

population growth. Past and current economic impacts associated with activities listed in 

Table 7-1 already have been considered as part of the socioeconomic baseline presented in 

Section 2.5. For example, the economic impacts of existing enterprises such as mining, other 

electrical utilities, etc., are part of the base used for establishing the Regional Input-Output 

Model System (RIMS) II multipliers. Regional planning efforts and associated demographic 

projections formed the basis for the review team’s assessment of reasonably foreseeable future 

impacts. State and county plans along with modeled demographic projections like those used in 

Sections 2.5, 4.4, and 5.4 include forecasts of future development and population increases. 

Thus, cumulative impacts associated with general growth in Matagorda and Brazoria Counties 

and construction, preconstruction, and operation of proposed Units 3 and 4 are evaluated in 

Chapters 4 and 5. 

Regarding specific reasonably foreseeable future projects that are not part of general growth in 

the region, the proposed 1320-MW WSEC listed in Table 7-1 is large enough that if its 

construction period coincided with that for proposed Units 3 and 4, some of the impacts of STP 

construction on schools, housing, and public services in Matagorda County might be more 

significant than if only Units 3 and 4 were built. The review team determined the construction 
Cumulative Impacts 

NUREG-1937 7-38 February 2011 

periods for WSEC and Units 3 and 4 are likely to overlap. WSEC is projected to begin 

construction in 2011 and would require about 4 years to complete (construction is planned to be 

completed in 2015). The WSEC project is expected to employ 1500 construction workers and 

150 operations workers, so a likely outcome is that WSEC construction would be at its highest 

just as construction of the first new STP unit would also be increasing (WSEC 2010). WSEC is 

in the vicinity of STP and would further alter the current viewshed. This would have a noticeable 

effect on the viewshed, but it would not be destabilizing. 

In September 2008, Exelon Generation submitted a COL application to the NRC for two nuclear 

power units at a site in Victoria County, Texas, about 55 mi southeast of the STP site (Exelon 

2008). However, the application was subsequently withdrawn and Exelon submitted an ESP 

application on March 25, 2010 (Exelon 2010). Exelon has no plans for onsite activity at the 

Victoria County site after issuance of an ESP, so construction of the Victoria County Station 

could be delayed as much as 20 years, resulting in no construction period impact and much 

delayed impact of any kind in Matagorda or Brazoria Counties. However, even if the 

construction periods overlap to some extent, Victoria County Station is not likely to significantly 

exacerbate the impacts of STP Units 3 and 4 on Matagorda and Brazoria Counties. Because of 

lengthy commuting distances involved, it is unlikely that large numbers of Victoria County 

Station workers would in-migrate to Matagorda or Brazoria Counties. Workers would likely 

prefer Victoria County with smaller numbers relocating to Calhoun and Jackson Counties, due 

to their more limited services. Construction workers already resident in Victoria County, 

however, could commute to the STP projects, reducing the need to import construction labor 

specifically for STP Units 3 and 4. Moreover, the property tax base represented by the WSEC 

(investment is projected at $2.5 billion) could be available when needed to pay for any public 

infrastructure improvements that would be required to support STP-related population growth. 

The Victoria County Station would not add to physical or aesthetic and recreational impacts in 

Matagorda County because of its distance from STP. 

The proposed Mary Rhodes Pipeline Phase II water project would be built from the Colorado 

River near Bay City through Matagorda and Jackson Counties, once the City Corpus Christi 

needs the water. Current plans call for the project to be operational no earlier than 2020 (City of 

Corpus Christi 2009), so construction likely would start just after completion of STP Unit 4. No 

information seems to be publically available concerning employment levels. Although the 

pipeline would cost in excess of $100 million to construct, it would be owned by a public entity 

and would not be taxable. Once buried, the pipeline would likely have little or no impact on 

aesthetics of the area. The proposed Matagorda Ship Channel Improvement Project is 

projected to occur in 2011 and would cause a small increase in construction employment and 

local purchases of construction materials. The socioeconomic impact was described as 

beneficial (Corps 2009), mainly in the Calhoun County area. The project would not overlap 

substantially with construction at STP Units 3 and 4. 
Cumulative Impacts 

February 2011 7-39 NUREG-1937 

The other major future projects shown in Table 7-1 are the Calhoun LNG terminal, and the E.S. 

Joslin Power Plant Project, NuCoastal Power Holdings’ proposed repowering project for a 

closed power plant. Both facilities are about 25 mi west-southwest from the STP site near Port 

Lavaca. The Calhoun LNG project would employ about 645 workers at peak activity, of whom 

an estimated 416 would be non-residents (FERC 2007). No employment information appears to 

be available on the repowering project. Taken together, these two projects likely would have 

noticeable but not destabilizing impacts on Calhoun County. The Calhoun LNG project, if it 

overlapped with STP, could add population and socioeconomic impact on Matagorda County in 

addition to that of proposed Units 3 and 4. The E.S. Joslin Power Plant project is expected to 

be completed by 2012 and is unlikely to exacerbate socioeconomic impacts of STP 

construction. Neither Calhoun County project would add to physical or aesthetic and 

recreational impacts because of their distance from STP. 

During the preconstruction and prior to the construction phases of proposed Units 3 and 4, the 

existing barge slip on the Lower Colorado River would need to be rehabilitated through dredging 

and construction of bulk heading. The existing navigation channel in the Colorado River, which 

is approximately 200-ft wide and 12-ft deep, is dredged as-needed by the Corps. STPNOC has 

not included dredging of the navigation channel of the Colorado River for barge access as part 

of the proposed action. However, alterations to traffic patterns within the Colorado River during 

rehabilitation and dredging of the existing barge slip at the STP site may occur. In addition, a 

slight increase in barge traffic associated with the barging of heavy equipment may occur during 

the construction phase. This increase in barge traffic during construction would be temporary; 

no additional barge traffic is expected in association with the operation of proposed Units 3 and 

4. Additional past and present actions within the geographic area of interest that contribute to 

barge traffic include the active Port of Bay City located approximately 8 mi upstream of STP. 

The Port of Bay City is a small barge terminal with a liquid cargo dock, a concrete dock, a low 

level heavy duty dock and a turning basin. Reasonably foreseeable future actions that may 

contribute to barge traffic on the Colorado River includes the construction of WSEC and the 

decommissioning of proposed Units 3 and 4. Based on its evaluation, the review team has 

concluded that the incremental impact of the proposed Units 3 and 4 on marine or recreational 

navigation when added to other past, present and reasonably foreseeable future actions within 

the geographic area of interest would be minor. 

The remaining projects in the socioeconomic impact area (Table 7-1) are either already 

operational or part of general growth in the region. In either case they are included in the 

socioeconomic baseline discussed in Section 2.5 and are already included in the impacts 

assessments in Sections 4.4 and 5.4. Because the projects within the socioeconomic impact 

area identified in Table 7-1 would be consistent with applicable county plans and policies, the 

review team considers the cumulative socioeconomic impacts from the projects to be 

manageable, particularly over time. 
Cumulative Impacts 

NUREG-1937 7-40 February 2011 

The review team has considered the cumulative impacts of construction, preconstruction, and 

operation of Units 3 and 4 plus other past, present, and reasonably foreseeable future activities 

over the life of the two new units. Based on the above considerations, information provided by 

STPNOC, and the review team’s independent review, the review team concludes that NRCauthorized construction of proposed Units 3 and 4 could make a temporary detectable adverse 

contribution to the cumulative effects associated with some socioeconomic issues under certain 

circumstances, and adverse socioeconomic impacts would be mostly confined to Matagorda 

County. Cumulative impacts on demography, traffic, housing availability, schools, and possibly 

emergency services such as police and fire protection staffing during construction would likely 

be MODERATE and adverse. It is unlikely that peak construction of the WSEC, Victoria County 

Station and the two Port Lavaca projects would coincide. If the local community would have to 

absorb more than one of these projects at once, significant adverse cumulative impacts on 

schools, housing, and traffic in Matagorda County could occur. Mitigation may be warranted for 

these impacts, especially for schools in the county and traffic congestion near STP. Even with 

the cumulative population increases and additional facilities, there would not be significant 

changes in the character of offsite noise, offsite dust or offsite recreation opportunities in 

Matagorda County and these impacts would be SMALL. 

Housing and schools may experience noticeable adverse cumulative impacts due to 

mismatches between demand and capacity early in the operations period if the identified 

projects coincide. In general, however, because even the combined population increases would 

be slight during the operations period, adverse socioeconomic cumulative impacts during 

operations would be SMALL, with no mitigation required. During operations, Matagorda County 

would experience LARGE beneficial increases in tax revenue as a result of STP Units 3 and 4, 

and this impact would be increased further by an operating WSEC. WSEC would noticeably 

change the viewshed in the vicinity of STP. The incremental contribution would be minimal from 

proposed Units 3 and 4 because the offsite view of the STP site would not change significantly 

given that existing Units 1 and 2 are currently within the viewshed. This results in a 

MODERATE and adverse cumulative aesthetic impact, and the incremental contribution from 

NRC-authorized construction would be SMALL and adverse. Because the cumulative project 

workforces living in Calhoun and Jackson and other nearby counties are likely to be relatively 

unnoticed and Brazoria County’s population is large relative to projected population increases 

associated with all of the projects taken together, the cumulative impact on the regional 

economies and tax revenues would be beneficially SMALL to MODERATE in Calhoun County 

(the site of the two Port Lavaca plants), and beneficially SMALL in Jackson County, Brazoria 

County, and the remainder of the 50-mi region. The incremental contribution from NRCauthorized construction would be SMALL in Calhoun, Jackson, and Brazoria County. 

7.4.2 Environmental Justice 

The description of the affected environment in Section 2.6 serves as a baseline for the 

cumulative impacts assessment in this resource area. As described in Section 4.5, there would 
Cumulative Impacts 

February 2011 7-41 NUREG-1937 

be no disproportionate adverse impacts to minority or low-income populations from NRCauthorized construction, and therefore the environmental justice impacts from NRC-authorized 

construction would be SMALL. Similarly, as described in Section 5.5, there would be no 

disproportionate adverse impacts to minority or low-income populations from operations, and 

therefore the environmental justice impacts from operations would be SMALL. 

The combined impacts from construction and preconstruction are described in Section 4.5 and 

determined to be SMALL. In addition to the impacts from construction, preconstruction, and 

operations, the cumulative analysis also considers other past, present, and reasonably 

foreseeable future projects that could cause environmental justice impacts on minority and lowincome populations. For this cumulative analysis, the general geographic area of interest is the 

50-mi region described in Section 2.5.1, which is the area most likely to experience health 

effects (if any) and provide the workforce for proposed Units 3 and 4. This is the region for 

which census block groups were assessed. However, subsets of the area were considered 

based on the area likely to be both influenced by the particular impact of proposed Units 3 and 

4. For example, the areas for which socioeconomic impacts were considered was limited to the 

four-county area expected to experience noticeable socioeconomic impacts from Units 3 and 4. 

From an environmental justice perspective, there is a potential for minority and low-income 

populations to be disproportionately affected by environmental impacts. In Matagorda County, 

the review team found low-income, Black, Asian, Hispanic and aggregated minority populations 

that exceed the percentage criteria established in Section 2.6.1 for environmental justice 

analyses. Further, one of the Asian census block groups is within 10 mi of STP near Palacios. 

The impact analyses in Chapters 4 and 5 are cumulative by nature. Past or current 

environmental justice impacts associated with activities listed in Table 7-1 already have been 

considered as part of the environmental justice baseline presented in Section 2.6 and there 

were no subsistence and cultural practices noted for any of the minority populations in the 

region that would make them vulnerable to environmental impacts from STP Units 3 and 4. 

Also, there were no offsite environmental impacts identified in Sections 4.5.1 and 5.5.1 that 

would affect any minority or low-income population, so STP Units 3 and 4 would not have any 

offsite environmental impacts on minority and low-income populations, even if there were 

environmental impacts on these populations from the WSEC and the two energy projects 

identified at Port Lavaca. The review team considers the proposed Victoria County Station to 

be too far away from Matagorda County in particular to have any socioeconomic or health 

impacts in Matagorda County. Thus, there would be no cumulative environmental impacts 

associated with building and operating of STP Units 3 and 4 beyond those already evaluated in 

Chapters 4 and 5 and no disproportionate environmental impacts on minority and low income 

populations. 

Other reasonably foreseeable future projects in the socioeconomic impact area (Table 7-1) 

would not likely contribute to additional environmental justice impacts through socioeconomic 
Cumulative Impacts 

NUREG-1937 7-42 February 2011 

pathways. The review team found no unusual socioeconomic circumstances, resource 

dependencies, or cultural practices through which minority or low-income populations would be 

disproportionately and adversely affected. There could be general adverse socioeconomic 

impacts through increased traffic and crowding of schools in the event that WSEC and STP 

construction coincided, but such impacts would be the same for all segments of the population 

because the review team did not find any evidence of unique characteristics or practices in the 

minority and low-income populations that may result in different impacts compared to the 

general population. The review team determined that the construction periods for the WSEC 

and STP Units 3 and 4 are likely to overlap, as described in Section 7.4.1. The cost of rental 

housing in Matagorda County might escalate if construction workers crowded into those 

counties, which would be more likely if WSEC and STP and the two Port Lavaca energy 

projects were being built at the same time. It is unlikely that the impact would disproportionately 

fall on the diffuse (i.e., unmapped) minority and low-income individuals in these counties since 

low-income rental housing is not the usual preference of high-income construction workers; 

rather, if rent increases happened, all population groups would be affected. However, the 

review team found no evidence of any unique characteristics or practices that would result in 

any minority or low-income population to be disproportionately affected by such rental 

increases. As a result, the review team concluded that there would be no disproportionate and 

adverse cumulative impact on minorities and low-income populations. Therefore, the 

cumulative environmental justice impacts of construction, preconstruction, and operation of 

proposed Units 3 and 4 and other past, present, and reasonably foreseeable future projects 

would be SMALL. 

7.5 Historic and Cultural Resources 

The description of the affected environment in Section 2.7 serves as a baseline for the 

cumulative impacts assessment in this resource area. As described in Section 4.6, impacts to 

cultural resources from NRC-authorized construction would be SMALL. As described in Section 

5.6, the review team concluded that the impacts to cultural resources from operations would be 

SMALL. Mitigative actions may be warranted only in the event of an unanticipated discovery 

during any ground-disturbing activities associated with construction or maintenance of the 

operating facility; these mitigative actions would be determined by STPNOC in consultation with 

the Texas State Historic Preservation Officer (SHPO). STPNOC has agreed to follow 

procedures if historic or cultural resources are discovered. These procedures are detailed in 

STPNOC’s Addendum 5 to procedure No. OPGP03-ZO-0025 Rev. 12 (Unanticipated Discovery 

of Cultural Resources) (STPNOC 2008b); the procedure includes notification of the SHPO at the 

Texas Historical Commission (THC) and affected Tribe(s) or other parties depending on the 

nature of the find. 

The combined impacts from construction and preconstruction are described in Section 4.6 and 

determined to be SMALL. Impacts associated with operations as described in Section 5.6 also 
Cumulative Impacts 

February 2011 7-43 NUREG-1937 

are determined to be SMALL. In addition to the impacts from construction, preconstruction, and 

operations, the cumulative analysis also considers other past, present, and reasonably 

foreseeable future projects that could affect historical and cultural resources. Section 2.7 

defines the physical area of potential effect (APE) for cultural resources, which is the area at the 

STP site and the immediate environs that may be impacted by land-disturbing activities 

associated with building and operating the two new nuclear generating units.. In addition to the 

physical APE, a visual APE has been established as a geographic area consisting of a 1-mi 

radius from the proposed project footprint. Both the physical and visual APEs are considered 

the geographic area of interest for this cumulative analysis. 

The cumulative impacts assessment considers all cultural resources within the APEs, including 

those that are eligible for listing on the National Register of Historic Places. Consultation with 

the Texas SHPO has confirmed that none of these historic properties are known within the 

physical or visual APEs at the STP site (THC 2010), and the Alabama-Coushatta Tribe has 

confirmed that the proposed action will cause no known impacts to resources of importance to 

the Tribe (Celestine 2010). 

As described in Section 2.7, regional settlement patterns suggest that prehistoric people lived 

along the Colorado River; however, few archaeological and cultural resource surveys have been 

conducted along the Colorado River to identify resources. The archaeological sites record 

search indicated that prehistoric sites have been located adjacent to the STP plant. Historically, 

Native American groups known collectively by the Europeans as the Karankawa, lived in the 

general area of the STP site during early Spanish and French Exploration. The French 

attempted to settle the Matagorda Bay area in 1685 and again in 1718, but neither attempt was 

successful, largely due to conflict with the Karankawa Indians. Historic settlement of the area 

commenced when Stephen F. Austin obtained a grant from the Mexican government in 1821 to 

permit 300 American families to settle along the Colorado River. When an additional 3000 

families were allowed to settle in the area in 1828, population increased rapidly. Matagorda 

County was created in 1837, shortly after Texas gained its independence from Mexico. Farming 

in the Matagorda region concentrated on sugar and cotton production, and following the Civil 

War, cattle ranching. 

Table 7-1 identifies other past, present and reasonably foreseeable future projects and other 

actions considered in the cumulative analysis of the STP site. Projects within the geographic 

area of interest that may have a potential cumulative impact on cultural resources include 

continued operation, and decommissioning for STP Units 1 and 2, and transmission lines and 

future urbanization. Such projects could impact cultural resources if ground-disturbing activities 

occur, or if new above-ground structures alter the historic setting or visual characteristics of 

resources within the visual APE. 

Cultural resources are non-renewable; therefore, the impact of destruction of cultural resources 

is cumulative. Based on the information provided by the applicant and the review team’s 
Cumulative Impacts 

NUREG-1937 7-44 February 2011 

independent evaluation, the review team concludes that the cumulative impacts from 

preconstruction, construction and operation of two new nuclear generating units on the STP site 

and from other projects within the geographic area of interest would be SMALL. However, 

those activities identified in Table 7-1 related to transmission line corridors associated with new 

energy development projects in the region and future urbanization do have the potential to 

impact cultural resources within the physical and visual APEs. Should these activities result in 

alterations to the cultural environment, then the impact could be greater. 

7.6 Air Quality 

The description of the affected environment in Section 2.9 serves as a baseline for the 

cumulative impacts assessment in this resource area. As described in Section 4.7, the impacts 

of NRC-authorized construction activities on air quality impacts would be SMALL, and no further 

mitigation would be warranted. As described in Section 5.7, the review team concludes that the 

impacts of operations on air quality impacts would be SMALL and no further mitigation would be 

warranted. 

7.6.1 Criteria Pollutants 

The combined impacts from construction and preconstruction are described in Section 4.7 and 

determined to be SMALL. In addition to the impacts from construction, preconstruction, and 

operations, the cumulative analysis also considers other past, present, and reasonably 

foreseeable future actions that could contribute to cumulative impacts to air quality. For this 

cumulative analysis of criteria pollutants, the geographic area of interest is Matagorda County 

which is within the Metropolitan Houston-Galveston Intrastate Air Quality Control Region 

(40 CFR 81.38). Air quality attainment status for Matagorda County as set forth in 40 CFR 

81.344 reflects the effects of past and present emissions from all pollutant sources in the region. 

Matagorda County is not out of attainment of any National Ambient Air Quality Standard. 

The air quality impact of site development for proposed Units 3 and 4 would be local and 

temporary. The distance from building activities to the site boundary would be sufficient to 

generally avoid significant air quality impacts. The WSEC project would be located about 5 mi 

northeast of the STP site, but it is unlikely construction of the two projects would overlap 

because WSEC is scheduled to begin construction 2 years earlier than construction of proposed 

Units 3 and 4. If construction overlaps, it is likely that construction of WSEC would be declining 

as construction of Units 3 and 4 is increasing (WSEC 2009). There are no land uses or 

projects, including the WSEC, that would have emissions during site development that would, in 

combination with emissions from STP Units 3 and 4, result in degradation of air quality in the 

region. 
Cumulative Impacts 

February 2011 7-45 NUREG-1937 

Combustion equipment associated with the operation of STP Units 1 and 2 is similar to the 

equipment that would be associated with Units 3 and 4. Releases are intermittent and made at 

low levels with little or no vertical velocity. Because of the intermittent nature of the releases 

and the small quantities of effluents being released, the review team expects that the cumulative 

impacts of combustion product release associated with the four STP units would be negligible. 

The WSEC is a proposed 1320-MW petroleum coke/bituminous-fired plant. Impacts from the 

emissions from similar plants are characterized as being clearly noticeable but not destabilizing 

in Section 9.2.2.1. Effluents from power plants such the WSEC are typically released through 

stacks and with significant vertical velocity. Other new industrial projects listed in Table 7-1 

would have de minimis impacts. Given that these other projects would be subject to institutional 

controls, it is unlikely that the air quality in the region would degrade to the extent that the region 

would be in nonattainment of National Ambient Air Quality Standards. 

7.6.2 Greenhouse Gas Emissions 

As discussed in the state of the science report issued by the GCRP, it is the “... production and 

use of energy that is the primary cause of global warming, and in turn, climate change will 

eventually affect our production and use of energy. The vast majority of U.S. greenhouse gas 

emissions, about 87 percent, come from energy production and use...” Approximately one third 

of the greenhouse gas emissions are the result of generating electricity and heat (GCRP 2009). 

This assessment is focused on greenhouse gas emissions. 

Greenhouse gas emissions associated with building, operating, and decommissioning a nuclear 

power plant are addressed in Sections 4.7, 5.7.1, 6.1.3, and 6.3. The review team concluded 

that the atmospheric impacts of the emissions associated of each aspect of building, operating 

and decommissioning a single plant are minimal. The review team also concludes that the 

impacts of the combined emissions for the full plant life cycle are minimal. 

The cumulative impacts of a single source or combination of greenhouse gas emission sources 

must be placed in geographic context: 

• The environmental impact is global rather than local or regional 

• The effect is not particularly sensitive to the location of the release point 

• The magnitude of individual greenhouse gas sources related to human activity, no matter 

how large compared to other sources, are small when compared to the total mass of 

greenhouse gases resident in the atmosphere, and 

• The total number and variety of greenhouse gas emission sources is extremely large and 

are ubiquitous. 

These points are illustrated in Table 7-2. 
Cumulative Impacts 

NUREG-1937 7-46 February 2011 

Table 7-2. Comparison of Annual Carbon Dioxide Emission Rates 

Source 

Metric Tons 

per Year 

Global Emissions 28,000,000,000(a)

United States 6,000,000,000(a)

1000 MW Nuclear Power Plant (including fuel cycle, 90 percent capacity factor) 400,000(b)

1000 MW Nuclear Power Plant (operations only, 90 percent capacity factor) 5000(b)

Average U.S. Passenger Vehicle(c) 5 

(a) Source: EPA 2009g 

(b) Source: Appendix I 

(c) Source: FHWA 2006 

Evaluation of cumulative impacts of greenhouse gas emissions requires the use of a global 

climate model. The GCRP report referenced above provides a synthesis of the results of 

numerous climate modeling studies. The review team concludes that the cumulative impacts of 

greenhouse emissions around the world as presented in the report are the appropriate basis for 

its evaluation of cumulative impacts. Based on the impacts set forth in the GCRP report, and 

the CO2 emissions threshold criteria in the final EPA CO2 Tailoring Rule (75 FR 31514), the 

review team concludes that the national and worldwide cumulative impacts of greenhouse gas 

emissions are noticeable but not destabilizing. The review team further concludes that the 

cumulative impacts would be noticeable but not destabilizing, with or without the greenhouse 

gas emissions of the proposed project. 

Consequently, the review team recognizes that greenhouse gas emissions, including carbon 

dioxide, from individual stationary sources and, cumulatively, from multiple sources can 

contribute to climate change and that the carbon footprint is a relevant factor in evaluating 

energy alternatives. Section 9.2.5 contains a comparison of carbon footprints of the viable 

energy alternatives. 

7.6.3 Summary 

Cumulative impacts to air quality resources are estimated based in the information provided by 

STPNOC and the review team’s independent evaluation. Other past, present, and reasonably 

foreseeable future activities exist in the geographic areas of interest (local for criteria pollutants 

and global for greenhouse gas emissions) that could affect air quality resources. The 

cumulative impacts on criteria pollutants from emissions of effluents from the STP site, other 

projects, and the WSEC would be noticeable but not destabilizing, principally as a result of the 

contribution of WSEC. STP and other projects listed in Table 7-1 would have de minimis 

impacts. The national and worldwide cumulative impacts of greenhouse gas emissions are 

noticeable but not destabilizing. The review team concludes that the cumulative impacts would 

be noticeable but not destabilizing, with or without the greenhouse gas emissions from the STP 
Cumulative Impacts 

February 2011 7-47 NUREG-1937 

site. The review team concludes that cumulative impacts from other past, present, and 

reasonably foreseeable future actions on air quality resources in the geographic areas of 

interest would be MODERATE. The incremental contribution of impacts on air quality resources 

from building and operating proposed Units 3 and 4 would be SMALL. The incremental 

contribution of impacts on air quality resources from the NRC-authorized activities would also be 

SMALL. 

7.7 Nonradiological Health 

The description of the affected environment in Section 2.10 serves as a baseline for 

nonradiological health. As described in Section 4.8, the impacts from NRC-authorized 

construction would be SMALL, and no further mitigation would be warranted other than that 

described in STPNOC’s ER (STPNOC 2010a). As described in Section 5.8, the nonradiological 

health impacts from operation of the proposed Units 3 and 4 would also be SMALL, and would 

warrant no further mitigation. 

As described in Section 4.8, the combined nonradiological health impacts from construction and 

preconstruction would be SMALL, and no further mitigation would be warranted other than that 

described in STPNOC’s ER. In addition to the impacts from construction, preconstruction, and 

operations, the cumulative analysis also considers other past, present, and reasonably 

foreseeable future actions that could contribute to cumulative impacts to nonradiological health 

(Table 7-1). Based on the localized nature of nonradiological health impacts, the geographic 

area of interest for this cumulative impacts analysis includes projects within a 5-mi radius 

around the STP site; and for cumulative impacts associated with transmission lines, the 

geographic area of interest is the transmission system associated with the proposed Units 3 and 

4 (as described in Section 2.2.2). These geographic areas are expected to encompass the 

areas where public and worker health could be influenced by the proposed project in 

combination with any other past, present or reasonably foreseeable future actions. 

Current projects within the geographic areas of interest that could contribute to cumulative 

impacts for nonradiological health include the operation of STP Units 1 and 2, the Mouth of the 

Colorado River Project, operation of chemical and plastic manufacturing facilities (Equistar 

Chemicals LP Matagorda facility and OXEA Corporation Bay City plant), existing transmission 

lines, and existing urbanization. Reasonably foreseeable future projects in the geographic 

areas of interest that could contribute to cumulative impacts for nonradiological health include 

the WSEC, the LCRA-SAWS project, the Mary Rhodes Pipeline Phase II project, and potential 

future transmission line development and urbanization. 

Preconstruction, construction, and operation activities that have the potential to impact the 

nonradiological health of the public and workers include: exposure to fugitive dust and vehicle 

emissions, occupational injuries, noise from construction and operation, exposure to etiological 
Cumulative Impacts 

NUREG-1937 7-48 February 2011 

agents, exposure to electromagnetic fields (EMFs), and the transportation of construction 

materials and personnel to and from the STP site. There are no existing or future projects that 

could contribute to cumulative nonradiological health impacts of occupational injuries. Existing 

and potential development of new transmission lines could increase nonradiological health 

impacts from exposure to acute EMFs, however, as stated in Section 5.8.3, adherence to 

Federal criteria and State utility codes would create minimal cumulative nonradiological health 

impacts. With regard to chronic effects of EMFs, the scientific evidence on human health does 

not conclusively link extremely low frequency EMFs to adverse health impacts. Noise and 

vehicle emissions associated with current urbanization, three existing plastic and chemical 

manufacturing plants, current operations of STP Units 1 and 2, and the planned WSEC, could 

contribute to public nonradiological health impacts. However, as discussed in Sections 4.8 and 

5.8, the proposed Units 3 and 4 contributions to these impacts would be temporary and minimal, 

and existing and future facilities would likely comply with local, State, and Federal regulations 

governing noise and emissions. Section 7.10.2 discusses cumulative nonradiological health 

impacts related to additional traffic on the regional and local highway networks leading to and 

from the STP site, and the review team determines that these impacts would be minimal. 

In Section 5.8.1, the review team evaluated the health impacts of operating the existing STP 

Units 1 and 2 and two new proposed units at the STP site with regard to the ambient 

temperature of the MCR and the Colorado River, and the potential formation of thermophilic 

microorganisms, including those that can cause diseases (i.e., etiological agents). The 

evaluation indicated that operation of Units 3 and 4 would not likely increase the presence of 

etiological agents in the Colorado River. This is because the low frequency of discharge from 

the MCR would not be expected to encourage increased populations of thermophilic 

microorganisms, and the largest thermal plumes that could be generated would likely occur 

when river water conditions are not suitable for swimming or immersion. Furthermore, the low 

incidence of water-borne diseases in the geographic area of interest indicates that the public 

recreates in a manner that reduces their potential exposure to these organisms (TDSHS 2010). 

Three reasonably foreseeable future projects–the WSEC, the LCRA-SAWS project, and 

although outside the 5-mi radius for evaluating cumulative impacts, the Mary Rhodes Pipeline 

Phase II project–would use or divert river water upstream of STP, and could reduce freshwater 

river flow and increase the ambient river water temperature (WSEC 2009; TWDB 2006b; 

Neuces River Authority 2001). This cumulative effect on Colorado River conditions could be 

favorable for an increased presence of thermophilic microorganisms, and subsequently increase 

the risk of public exposure to etiological agents. However, based on the relatively low incidence 

rate of waterborne diseases from recreational water activities in Texas, cumulative impacts to 

nonradiological health from exposure to etiological agents in the Colorado River would likely be 

minimal (CDC 2009; TDSHS 2010). 
Cumulative Impacts 

February 2011 7-49 NUREG-1937 

The review team is also aware of the potential climate changes that could affect human health—

a recent compilation of the state of knowledge in this area (GCRP 2009) has been considered in 

the preparation of this EIS. Projected changes in the climate for the region during the life of 

proposed Units 3 and 4 include an increase in average temperature and a decrease in 

precipitation. Potential changes in water temperature and frequency of downpours could alter 

the presence of thermophilic microorganisms. While the changes that are attributed to climate 

change in these studies may not be insignificant nationally or globally, the review team did not 

identify anything that would alter its conclusion regarding the presence of etiological agents or 

change in the incidence of water-borne diseases in the geographical region of interest. 

Cumulative impacts to nonradiological health are based on information provided by STPNOC 

and the review team’s independent evaluation of impacts resulting from the building and 

operation of proposed Units 3 and 4, along with a review of potential impacts from other past, 

present, and reasonably foreseeable future projects and urbanization located in the geographic 

area of interest. The review team concludes that cumulative impacts on public and worker 

nonradiological health would be SMALL, and that mitigation beyond what is discussed in 

Sections 4.8 and 5.8 would not be warranted. The review team does acknowledge that there is 

no conclusive link between EMF exposure and human health impacts. 

7.8 Radiological Impacts of Normal Operation 

The description of the affected environment in Section 2.10 serves as a baseline for the 

cumulative impacts assessment in this resource area. As described in Section 4.9, the NRC 

staff concludes that the radiological impacts from NRC-authorized construction would be 

SMALL, and no further mitigation would be warranted. As described in Section 5.9, the NRC 

staff concludes that the radiological impacts from normal operations would be SMALL, and no 

further mitigation would be warranted. 

The combined impacts from construction and preconstruction were described in Section 4.9 and 

determined to be SMALL. In addition to impacts from construction, preconstruction, and 

operations, the cumulative analysis also considers other past, present, and reasonably 

foreseeable future actions that could contribute to cumulative radiological impacts. For this 

analysis, the geographic area of interest is the area within a 50-mi radius of the proposed Units 

3 and 4. Historically, the NRC has used the 50-mi radius as a standard bounding geographic 

area to evaluate population doses from routine releases from nuclear power plants. The 

geographic area of interest includes the existing operating STP Units 1 and 2, the Old Steam 

Generator Storage Facility, and the Onsite Staging Facility. STPNOC also plans to construct a 

Long Term Storage Facility to store replaced reactor vessel heads. Also, within the 50-mi 

radius of the site, there are likely to be hospitals and industrial facilities that use radioactive 

materials. 
Cumulative Impacts 

NUREG-1937 7-50 February 2011 

As stated in Section 2.11, STPNOC has conducted a radiological environmental monitoring 

program (REMP) around the STP site since 1986. The REMP measures radiation and 

radioactive materials from all sources, including the existing STP Units 1 and 2, hospitals, and 

industrial facilities. In 2008, the REMP detected concentrations of tritium in the MCR with 

maximum levels about 65 percent of the EPA drinking-water standard, which is 

20,000 picocuries per liter (pCi/L) for tritium, and in monitoring and relief wells within the site 

boundary at about 28 percent of the EPA standard. Tritium would be expected to be released 

by Units 3 and 4 in addition to that released by Units 1 and 2. Because Units 1 and 2 are 

pressurized water reactors and the proposed Units 3 and 4 are ABWRs, the additional annual 

contribution of tritium to the MCR from Units 3 and 4 is estimated to be a small fraction of 

current releases from Units 1 and 2. For example, the last five years’ annual effluent reports 

from STP (STPNOC 2005, 2006, 2007, 2008a, 2009b) indicate that the annual average amount 

of tritium released from Units 1 and 2 was 2080 curies (Ci), with a standard deviation of about 

460 Ci. Units 3 and 4 combined would annually release 16 Ci of tritium to the MCR, which is 

approximately 1 percent of the average release from Units 1 and 2. This amount is within the 

annual variation of the releases from Units 1 and 2. 

As described in Section 4.9, the estimate of doses to construction workers during building of the 

proposed Units 3 and 4 are well within NRC annual exposure limits (i.e., 100 millirem) designed 

to protect the public health. This estimate includes exposure from Units 1 and 2, the Old Steam 

Generator Storage Facility, the Onsite Staging Facility and the planned Long Term Storage 

Facility. The estimate of doses to construction workers during building Unit 4 includes Unit 3 as 

a source of exposure. As described in Section 5.9, the public and occupational doses predicted 

from the proposed operation of two new units at the STP site are well below NRC regulatory 

limits and standards. In addition, the dose to the maximally exposed individual (MEI) from the 

existing Units and the proposed Units 3 and 4 at the STP site would be well within the EPA 

regulatory standard of 40 CFR Part 190. Also, based on results of the REMP and the estimates 

of doses from proposed Units 3 and 4 to biota given in Chapter 5.9, the NRC staff concludes 

that the cumulative radiological impact on biota would not be significant. The results of the 

REMP indicate that effluents and direct radiation from area hospitals and industrial facilities that 

use radioactive materials do not contribute measurably to the cumulative dose.

Currently, there are no other nuclear facilities planned within 50 mi of the STP site. The NRC, 

the U.S. Department of Energy, and the State of Texas would regulate or control any 

reasonably foreseeable future actions in the region that could contribute to cumulative 

radiological impacts. Therefore, the NRC staff concludes that the cumulative radiological 

impacts of operating two new units, along with the existing units at STP and the influence of 

other man-made sources of radiation nearby would be SMALL, and no further mitigation would 

be warranted. 
Cumulative Impacts 

February 2011 7-51 NUREG-1937 

7.9 Postulated Accidents 

As described in Section 5.11.4, the NRC staff concludes that the potential environmental 

impacts (risk) from a postulated accident from the operation of proposed Units 3 and 4 would be 

SMALL. Section 5.11 considers both design basis accidents (DBAs) and severe accidents. 

As described in Section 5.11.1, the NRC staff concludes that the environmental consequences 

of DBAs at the STP site would be SMALL for an ABWR. DBAs are addressed specifically to 

demonstrate that a reactor design is robust enough to meet NRC safety criteria. The 

consequences of DBAs are bounded by the consequences of severe accidents. 

As described in Section 5.11.2, the NRC staff concludes that the severe-accident probabilityweighted consequences (i.e., risks) of an ABWR reactor at the STP site are SMALL compared 

to risks to which the population is generally exposed, and no further mitigation would be 

warranted. The cumulative analysis considers risk from potential severe accidents at all other 

existing and proposed nuclear power plants that have the potential to increase risks at any 

location within 50 mi of the proposed Units 3 and 4. The 50-mi radius was selected to cover any 

potential risk overlaps from 2 or more nuclear facilities. The only existing reactors within a 

50-mi radius of the STP site are STP Units 1 and 2. However, a nuclear power plant has been 

proposed for a site near Victoria, Texas, approximately 55 mi from the STP site. In March 2010, 

Exelon Generation submitted an ESP application to the NRC for the Victoria County Station 

(Exelon 2010). If the Victoria County Station was to be constructed and an accident was to 

occur at that facility, the consequences could potentially effect locations within the 50-mi radius 

of the STP site. 

Table 5-18 and 5-19 in Section 5.11.2 provide comparisons of estimated risk for the proposed 

ABWR units at the STP site and current-generation reactors. The estimated population dose 

risk for the proposed ABWR units at the STP site is well below the median value for currentgeneration reactors. In addition, estimates of average individual early fatality and latent cancer 

fatality risks are well below the Commission’s safety goals (51 FR 30028). For existing plants 

within the geographic area of interest (STP Units 1 and 2), the Commission has determined that 

the probability-weighted consequences of severe accidents are small (10 CFR 51, Appendix B, 

Table B-1). It is expected that risks for any new reactors at the Victoria County Station would be 

well below the risks for current-generation reactors and meet the Commission’s safety goals. 

On this basis, the NRC staff concludes that the cumulative risks of severe accidents at any 

location within 50 mi of the STP site likely would be SMALL and no further mitigation would be 

warranted. 
Cumulative Impacts 

NUREG-1937 7-52 February 2011 

7.10 Fuel Cycle, Transportation, and Decommissioning 

The cumulative impacts related to the fuel cycle, radiological and nonradiological aspects of 

transportation, and facility decommissioning for the proposed site are described below. 

7.10.1 Fuel Cycle 

As described in Section 6.1, the NRC staff concludes that the impacts of the fuel cycle due to 

operation of proposed Units 3 and 4 would be SMALL. Fuel-cycle impacts would occur not only 

at the STP site but would also be scattered through other locations in the United States or, in 

the case of foreign-purchased uranium, in other countries. 

In addition to fuel-cycle impacts from proposed Units 3 and 4, this cumulative analysis also 

considers fuel-cycle impacts from existing Units 1 and 2. There are no other nuclear power 

plants within 50 mi of the STP site. The fuel-cycle impacts of Units 1 and 2 would be similar to 

that of proposed Units 3 and 4. Per 10 CFR 51.51(a), the NRC staff concludes that impacts 

would be acceptable for the 1000-MW(e) reference reactor. The impacts of producing and 

disposing of nuclear fuel include mining the uranium ore, milling the ore, converting the uranium 

oxide to uranium hexafluoride, enriching the uranium hexafluoride, fabricating the fuel (where 

the uranium hexafluoride is converted to uranium oxide fuel pellets), and disposing of the spent 

fuel in a proposed Federal waste repository. As discussed in Section 6.1, advances in reactors 

since the development of Table S–3 in 10 CFR 51.51 would reduce environmental impacts 

relative to the operating reference reactor. For example, a number of fuel management 

improvements have been adopted by nuclear power plants to achieve higher performance and 

to reduce fuel and separative work (enrichment) requirements. In Section 6.1, the NRC staff 

multiplied the values in Table S–3 by a factor of approximately three, to scale the impacts up 

from the 1000-MW(e) LWR model to address the fuel cycle impacts of proposed Units 3 and 4. 

Adding the fuel cycle impacts from Units 1 and 2 would increase the scaling to no more than a 

factor of six. Therefore, the NRC staff considers the cumulative fuel-cycle impacts related to 

STP Units 3 and 4 to be SMALL. 

7.10.2 Transportation 

The description of the affected environment in Section 2.5.2 serves as a baseline for the 

cumulative impacts assessment in this resource area. As described in Sections 4.8.3 and 5.8.6, 

the review team concludes that impacts of transporting personnel and nonradiological materials 

to and from the STP site would be SMALL. In addition to impacts from preconstruction, 

construction, and operations, the cumulative analysis also considers other past, and present, 

and reasonably foreseeable future actions that could contribute to cumulative transportation 

impacts. For this analysis the geographic area of interest is the 50-mi region surrounding the 

STP site. 
Cumulative Impacts 

February 2011 7-53 NUREG-1937 

Nonradiological transportation impacts are related to the additional traffic on the regional and 

local highway networks leading to and from the STP site. Additional traffic would result from 

shipments of construction materials and movements of construction personnel to and from the 

site. The additional traffic increases the risk of traffic accidents, injuries, and fatalities. A review 

of the projects listed in Table 7-1 indicates that other projects in the region could potentially 

increase nonradiological impacts. The most significant cumulative nonradiological impacts in 

the vicinity of the STP site would result from major construction projects, including the WSEC, 

Calhoun LNG Terminal, ES Joslin Power Plant Project, Matagorda Ship Channel Improvement 

Project, and highway improvement projects. The WSEC project is located about 5 mi northeast 

of the STP site, but it is unlikely construction of the two projects would overlap because WSEC 

is scheduled to begin construction 2 years earlier than construction of proposed Units 3 and 4. 

If construction overlaps, it is likely that construction of WSEC would be declining as construction 

of Units 3 and 4 is increasing (WSEC 2009). Consequently, interactions among construction 

traffic are unlikely to exacerbate congestion and potentially increase nonradiological 

transportation impacts. The other construction projects are more than 25 mi from the STP site, 

and therefore the traffic from these projects is not likely to interact with traffic associated with 

building and operating the STP site. 

Traffic associated with the existing STP Units 1 and 2 and the WSEC could interact with traffic 

associated with proposed Units 3 and 4. However, STPNOC has identified mitigation measures 

designed to reduce traffic impacts in the vicinity of the STP site; these mitigation measures 

would also reduce traffic impacts to and from the WSEC. Traffic flow to and from operating 

facilities in the region would be of lesser importance because fewer workers and material 

shipments are needed to support operating facilities than major construction projects. The 

operating facilities with potential for cumulative nonradiological impacts include Equistar 

Chemicals LP’s Matagorda facility, OXEA Corporation’s Bay City plant, and Texas Liquid 

Fertilizer Company Point Comfort. As with the construction projects, the mitigation measures 

identified by STPNOC for the proposed new units would also mitigate traffic concerns and 

reduce the potential cumulative nonradiological impacts associated with operating facilities. 

Finally, one park listed in Table 7-1, the Brazos Bend State Park, is located within the 

geographic area of interest. However, the park is located approximately 35 mi northeast of the 

STP site and no reasonably foreseeable potential park improvements have been identified. 

There are also three wildlife refuges or management areas within 10 mi of the STP Site. If 

potential improvements occur, they are generally of smaller scope and have lower resource and 

personnel requirements than constructing a new nuclear power plant. Therefore, park and 

wildlife refuge/management area improvements are not likely to result in a measurable 

cumulative impact. 

In Sections 4.8.3 and 5.8.6, the review team concluded that the impacts of transporting 

construction material and construction and operations personnel to and from the STP site is a 
Cumulative Impacts 

NUREG-1937 7-54 February 2011 

small fraction of the existing nonradiological impacts in Matagorda County, Texas. Mitigation 

measures designed to improve traffic flow at the STP site have been identified by STPNOC 

(2009a). Based on the magnitude of nuclear power plant construction relative to the other 

construction activities listed above, the review team concludes the cumulative nonradiological 

transportation impacts of constructing and operating the proposed new reactor at the STP site 

would be SMALL and no further mitigation is warranted. 

As described in Section 6.2, the NRC staff concludes that impacts transporting unirradiated fuel 

to the STP site and irradiated fuel and radioactive waste from the STP site would be SMALL. In 

addition to impacts from preconstruction, construction, and operations, the cumulative analysis 

also considers other past, present, and reasonably foreseeable future actions that could 

contribute to cumulative transportation impacts. For this analysis, the geographic area of 

interest is the 50-mi region surrounding the STP site. 

Historically, the radiological impacts to the public and environment associated with 

transportation of radioactive materials in the 50-mi region surrounding the STP site have been 

primarily associated with shipments of fuel and waste to and from the existing STP Units 1 and 

2. Radiological impacts of transporting radioactive materials would occur along the routes 

leading to and from the STP site, fuel fabrication facilities, and waste disposal sites located in 

other parts of the United States. No other major activities with the potential for cumulative 

radiological impacts were identified in the geographic region of interest. The past, present, and 

reasonably foreseeable future impacts in the region surrounding the STP site are a small 

fraction of the impacts from natural background radiation. 

As discussed in Section 6.2, the addition of the proposed new units to the existing STP site 

would result in the need for additional unirradiated nuclear fuel and generation of additional 

spent nuclear fuel and radioactive waste. The impacts of transporting this fuel and radioactive 

waste to and from the STP site would be consistent with the environmental impacts associated 

with transportation of fuel and radioactive wastes from current-generation reactors presented in 

Table S-4 of 10 CFR 51.52, which the NRC staff considers to be acceptable for the 1000-MW(e) 

reference reactor. Advances in reactor technology and operations since the development of 

Table S-4 would reduce environmental impacts relative to the values in Table S-4. For 

example, fuel management improvements have been adopted by nuclear power plants to 

achieve higher performance and to reduce fuel requirements. This leads to fewer unirradiated 

and spent fuel shipments than the 1000 MW(e) reference reactor discussed in 10 CFR 51.52. 

In addition, advances in shipping cask designs to increase their capabilities would result in 

fewer shipments of spent fuel to offsite storage or disposal facilities. 

Therefore, the NRC staff considers the cumulative radiological and nonradiological 

transportation impacts of operating the proposed new reactors at the STP site to be SMALL and 

no further mitigation would be warranted. 
Cumulative Impacts 

February 2011 7-55 NUREG-1937 

7.10.3 Decommissioning 

As discussed in Section 6.3, the environmental impacts from decommissioning the proposed 

Units 3 and 4 are expected to be SMALL, because the licensee would have to comply with 

decommissioning regulatory requirements. 

In this cumulative analysis, the geographic area of interest is within a 50-mi radius of the STP 

site. In addition to the proposed Units 3 and 4, the only other nuclear power plants within this 

geographic area of interest are the existing STP Units 1 and 2. The impacts of 

decommissioning nuclear power plants are bounded by the assessment in Supplement 1 to 

NUREG-0586, Generic Environmental Impact Statement on Decommissioning of Nuclear 

Facilities. In that document, the NRC found the impacts on radiation dose to workers and the 

public, waste management, water quality, air quality, ecological resources, and socioeconomics 

to be SMALL (NRC 2002). In addition, in Section 6.3 the NRC staff concluded that the impact of 

greenhouse gas emissions on air quality during decommissioning would be SMALL. Therefore, 

the cumulative impacts for the STP site would be SMALL, and further mitigation would not be 

warranted. 

7.11 Conclusions 

The review team considered the potential cumulative impacts resulting from construction, 

preconstruction, and operation of two additional nuclear units at the STP site together with other 

past, present, and reasonably foreseeable future actions. The specific resources that could be 

affected by the incremental effects of the proposed action when considered with other actions 

listed in Table 7-1 in the same geographic area were assessed. This assessment included the 

impacts of construction and operation for the proposed new units as described in Chapters 4 

and 5; impacts of preconstruction activities as described in Chapter 4; impacts of fuel cycle, 

transportation, and decommissioning impacts described in Chapter 6; and impacts of past, 

present and reasonably foreseeable future Federal, non-Federal, and private actions that could 

affect the same resources affected by the proposed action. 

Table 7-3 summarizes the cumulative impacts by resource area. The cumulative impacts for the 

majority of resource areas would be SMALL, although there could be MODERATE or LARGE 

impacts for some resources, as discussed below. 

Cumulative land-use impacts in the geographic area of interest would be MODERATE, primarily 

due to the proposed WSEC project and associated transmission lines, future urbanization, and 

GCC. The incremental impact from NRC-authorized activities on land use would be SMALL 

because the affects to land use from building and operating Units 3 and 4 would be minimal. 

The cumulative surface water use impacts would be MODERATE, primarily due to the impacts 

from existing and reasonably foreseeable projects that use surface water in Region K. The 
Cumulative Impacts 

NUREG-1937 7-56 February 2011 

incremental impacts from the proposed action and NRC-authorized activities would be SMALL 

and not noticeably alter water use in the Region. The cumulative surface water quality impacts 

in the geographic area of interest would be MODERATE, primarily due to point and nonpoint 

sources that have resulted in the impairment of the Colorado River, which is currently on the 

State’s 303(d) list. The incremental impact from NRC-authorized activities would be SMALL 

because such impacts would be localized and temporary. 

Table 7-3. Cumulative Impacts on Environmental Resources, Including the Impacts of 

Proposed Units 3 and 4 

Resource Category Impact level 

Land-Use MODERATE 

Water-Related 

 Water Use-Surface Water MODERATE 

 Water Use-Groundwater SMALL 

 Water Quality-Surface Water MODERATE 

 Water Quality-Groundwater SMALL 

Ecology 

 Terrestrial Ecosystems MODERATE 

 Aquatic Ecosystems MODERATE 

Socioeconomic 

 Physical Impacts SMALL to MODERATE 

 Demography SMALL to MODERATE 

 Taxes and Economy SMALL to LARGE (beneficial) 

 Infrastructure and Community Service SMALL to MODERATE 

Environmental Justice SMALL 

Historic and Cultural Resources SMALL 

Air Quality MODERATE 

Nonradiological Health SMALL 

Radiological Health SMALL 

Severe Accidents SMALL 

Fuel Cycle, Transportation, and Decommissioning SMALL 

Cumulative terrestrial ecology impacts in the geographic area of interest would be MODERATE, 

primarily due to detectable alteration of habitat, loss of habitat, increased fragmentation, and 

increased risk of collision and electrocution in the Central Migratory Corridor from urbanization, 

new transmission corridors associated with WSEC and other energy projects, and climate 

change. The incremental impact from NRC-authorized activities on terrestrial ecology would be 

SMALL because the contribution from STP Units 3 and 4 to these impacts is minimal. 
Cumulative Impacts 

February 2011 7-57 NUREG-1937 

The review team concludes that cumulative impacts from past, present, and reasonably 

foreseeable future actions to aquatic resources in the geographic area of interest would be 

MODERATE. Future development of industries that compete for water in the Colorado River as 

well as management of water budgets across the State of Texas through diversion projects like 

LCRA-SAWS project would likely affect aquatic resources in the lower Colorado River. Direct 

and indirect anthropogenic stressors, including GCC, in the geographic area of interest would 

cumulatively lead to effects on the aquatic communities that would be noticeable. The 

incremental contribution of impacts to aquatic resources in onsite water bodies from the 

operation of the proposed Units 3 and 4, in the Colorado River from operation of the RMPF and 

the discharge structure, and in offsite water bodies from maintenance and operation of the 

transmission corridors would be SMALL although under certain conditions, the thermal plume 

from the discharge of MCR water into the Colorado River could affect passage and potentially 

survival of some aquatic organisms in the river. 

For socioeconomics, cumulative impacts on taxes and economy would be SMALL to LARGE 

and beneficial. In Matagorda County, the cumulative impacts would be LARGE and beneficial 

once both Units 3 and 4 and WSEC are operational. The incremental impact on taxes and the 

economy from NRC-authorized activities in Matagorda County would be MODERATE and 

beneficial. In Calhoun County, the cumulative impacts on taxes and the economy would be 

SMALL to MODERATE and beneficial primarily due to the proposed Port Lavaca plants. The 

incremental impact on taxes and the economy from NRC-authorized activities in Calhoun 

County would be SMALL and beneficial. The cumulative impacts on demography and 

infrastructure (roads, housing, public services, and education) in Matagorda County would be 

MODERATE. Although NRC-authorized activities would contribute to noticeable alterations in 

demography and infrastructure, they would not likely result in destabilization of either resource. 

The cumulative aesthetics impacts would be MODERATE, principally because WSEC would 

noticeably change the viewshed in the vicinity of STP. The incremental contribution from NRCauthorized activities would be SMALL because the offsite view of the STP site would not change 

significantly with the addition of Units 3 and 4 given that Units 1 and 2 are currently within this 

viewshed. 

Cumulative air quality impacts in the geographic area of interest would be MODERATE, 

primarily due to national and world-wide impacts of greenhouse gases emissions and due to the 

impacts on criteria pollutants from the WSEC project. The incremental impacts from NRCauthorized activities would be SMALL, since such impacts would be minimal. 

The Galveston District of the Corps has developed a detailed approach to assessing the 

cumulative effects of a proposed action when considered with other past, present, and 

reasonably foreseeable future projects in the geographic area of interest for each resource. 

This approach was developed by the Corps to comply with the findings of several Federal court 

cases including: Fritiofson v. Alexander; Stewart v. Potts; Lafitte's Cove at Pirates’ Beach 

Nature Society v. U.S. Army Corps of Engineers; and Galveston Beach to Bay Preserve v. U.S. 
Cumulative Impacts 

NUREG-1937 7-58 February 2011 

Army Corps of Engineers. This method is in accordance with CEQ’s regulations (40 CFR 1500-

1508) and the CEQ’s guide to Considering Cumulative Effects Under the National 

Environmental Policy Act. Appendix J provides a table indicating which resources were 

considered in the Corps’ Cumulative Effects Assessment, which resources were included in this 

EIS and the sections of this EIS that detail the Corps considerations, and identifies which 

resources in the table were not considered in this EIS. 

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Cumulative Impacts 

NUREG-1937 7-66 February 2011 

http://oaspub.epa.gov/enviro/fii_query_dtl.disp_program_facility?p_registry_id=110018939158. 

Accession No. ML100630188. 

U.S. Environmental Protection Agency (EPA). 2009g. Global Greenhouse Gas Data. 

Accessed December 15, 2009 at http://www.epa.gov/climatechange/emissions/globalghg.html. 

Accession No. ML100221499. Accession No. ML100630188. 

U.S. Federal Energy Regulatory Commission (FERC). 2007. Final Environmental Impact 

Statement for the Proposed Calhoun LNG Terminal and Pipeline Project. Washington, D.C. 

Accessed February 8, 2010 at http://www.ferc.gov/industries/lng/enviro/eis/2007/08-10-07-

eis.asp. Accession No. ML100630188. 

U.S. Fish and Wildlife Service (FWS). 2010. Big Boggy National Refuge. Available at 

http://www.fws.gov/southwest/refuges/texas/texasmidcoast/bigboggy.htm. 

U.S. Global Change Research Program (GCRP). 2009. Global Climate Change Impacts in the 

10 United States. T.R. Karl, J.M. Melillo, and T.C. Peterson, eds. Cambridge University Press, 

11 New York. Available at http://downloads.globalchange.gov/usimpacts/pdfs/climate-impactsreport.pdf. 

U.S. Nuclear Regulatory Commission (NRC). 1975. Final Environmental Statement Related to 

the Proposed South Texas Project Units 1 & 2. NUREG-75/019, Washington, D.C. 

U.S. Nuclear Regulatory Commission (NRC). 1986. Final Environmental Statement Related to 

the Operation of South Texas Project, Units 1 and 2. NUREG-1171, Washington, D.C. 

U.S. Nuclear Regulatory Commission (NRC). 2002. Generic Environmental Impact Statement 

on Decommissioning of Nuclear Facilities. NUREG-0586, Supplement 1, Vol. 1, Washington, 

D.C. 

U.S. Nuclear Regulatory Commission (NRC). 2009. Site Audit Summary of South Texas 

Project Nuclear Operating Company’s Revised Alternative Sites Analysis. November 9, 2009. 

Accession No. ML092870574. 

U.S. Nuclear Regulatory Commission (NRC). 2010. Staff Memorandum from Scott Flanders, 

DSER Division Director, to Brent Clayton, RENV Branch Chief, dated December 10, 2010, 

“Addressing Construction and Preconstruction Activities, Greenhouse Gas Issues, General 

Conformity Determinations, Environmental Justice, Need for Power, Cumulative Impact 

Analysis, and Cultural/Historical Resources Analysis Issues In Environmental Impact 

Statements.” Accession No. ML100760503. 
Cumulative Impacts 

February 2011 7-67 NUREG-1937 

White Stallion Energy Center (WSEC). 2009. Economic Impact. Accessed November 18, 

2009 at http://whitestallionenergycenter.com/economicimpact.html. 

White Stallion Energy Center (WSEC). 2010. “Your Guide to the White Stallion Energy Center” 

Available at http://www.whitestallionenergycenter.com/wpcontent/uploads/2010/09/Guide_to_WSEC.pdf. 

Wilber, D.H. and R. Bass. 1998. “Effect of the Colorado River Diversion on Matagorda Bay 

Epifauna.” Estuarine, Coastal and Shelf Science 47:309-318. 

February 2011 8-1 NUREG-1937 

8.0 Need for Power 

Chapter 8 of the U.S. Nuclear Regulatory Commission’s (NRC’s) Environmental Standard 

Review Plan (ESRP) (NRC 2000), with additional clarification provided in NRC Staff 

Memorandum (NRC 2010), guides the NRC staff’s review and analysis of the need for power 

from a proposed nuclear power plant. In addition to the ESRP guidance, the NRC addressed 

need for power in a 2003 response to a petition for rulemaking (68 FR 55910). In the 2003 

response, the NRC reviewed whether or not need for power should be considered in NRC 

environmental impact statements (EISs) prepared in conjunction with applications that could 

result in construction of a new nuclear power plant. The NRC (68 FR 55910) concluded that: 

The need for power must be addressed in connection with new power plant 

construction so that the NRC may weigh the likely benefits (e.g., electrical power) 

against the environmental impacts of constructing and operating a nuclear power 

reactor. The Commission emphasizes, however, that such an assessment 

should not involve burdensome attempts to precisely identify future conditions. 

Rather, it should be sufficient to reasonably characterize the costs and benefits 

associated with proposed licensing actions. 

While the NRC will perform a need for power analysis for a new nuclear power plant in its EIS, 

the NRC also stated in its response to the petition that (1) the NRC does not supplant the 

states, which have traditionally been responsible for assessing the need for power-generating 

facilities, for their economic feasibility and for regulating rates and services; and (2) the NRC 

has acknowledged the primacy of state regulatory decisions regarding future energy options 

(68 FR 55910). 

8.1 Description of Power System 

8.1.1 Description of STPNOC 

The purpose of proposed Units 3 and 4 at the South Texas Project Electric Generating Station 

(STP) site is to provide baseload generation for use by the owners and/or for eventual sale on 

the wholesale market. As discussed in Chapter 1, it is planned that Unit 3 would be owned by 

Nuclear Innovation North America (NINA) Texas 3 LLC and the City of San Antonio, Texas, 

through the City Public Services Board (CPS Energy), and that Unit 4 would be owned by NINA 

Texas 4 LLC and CPS Energy. Both proposed units would be baseload merchant generator 

plants. NINA Texas 3 LLC and NINA Texas 4 LLC intend to sell their share of the power from 

Units 3 and 4 on the wholesale market. CPS Energy may either use its share of Units 3 and 4 

to supply the needs of its service area and/or sell the power on the wholesale market 

(STPNOC 2010). 
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NUREG-1937 8-2 February 2011 

The applicant, STP Nuclear Operating Company (STPNOC), stated in its application for 

combined licenses (COLs) that proposed Units 3 and 4 at the STP site would be unregulated 

entities. The electric utility industry in the State of Texas was deregulated in 2002. NRG 

Energy, the controlling majority owner of NINA, will be a merchant generator that does not have 

a specific service area. The other principal owner, CPS Energy, is a municipal utility that sells 

capacity in excess of its own retail service needs in the San Antonio area into the Electric 

Reliability Council of Texas (ERCOT) wholesale market (STPNOC 2010). Currently, CPS 

Energy has several wholesale contracts, for which it is seeking renewal, that amount to firm 

power obligations. In addition, CPS Energy’s native retail service area of Bexar County and the 

San Antonio vicinity also is growing in population and represents additional potential demand. 

However, in estimating the need for power for proposed Units 3 and 4, STPNOC is relying on 

ERCOT’s forecast of the overall demand for power in the ERCOT region rather than CPS 

Energy’s specific service and contract obligations (STPNOC 2010). 

8.1.2 Description of ERCOT 

STPNOC has defined the region of interest for evaluating the need for power as the entire area 

served by ERCOT, the independent system operator (ISO) for the electric grid for most of the 

State of Texas (Figure 8-1). 

ERCOT is a membership-based nonprofit corporation formed under 26 USC 501(c)(6) of the 

Internal Revenue Code. It is governed by a board of directors and subject to oversight by the 

Public Utility Commission of Texas (PUCT) and the Texas Legislature. ERCOT’s members 

include retail consumers, investor-owned and municipally-owned utilities, rural electric 

cooperatives, river authorities, independent generators, power marketers, and retail electric 

providers (ERCOT 2008a). The ERCOT board of directors is made up of independent 

members, consumers, and representatives from each of ERCOT’s electric market segments. 

The board of directors appoints ERCOT’s officers, who direct and manage day-to-day 

operations (ERCOT 2008b). ERCOT’s responsibilities include: 

• managing the flow of electric power to approximately 22 million Texas customers, 

representing 85 percent of the State’s electric load, 

• scheduling power on an electric grid with 40,000 mi of high-voltage transmission lines and 

more than 550 generation units, 

• managing financial settlements for the Texas competitive wholesale bulk-power market, and 

• administering of customer switching for 6.5 million Texans in competitive choice areas 

(ERCOT 2008c). 
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February 2011 8-3 NUREG-1937 

Figure 8-1. Map of the ERCOT ISO Service Area (STPNOC 2010)

As explained in STPNOC’s environmental report (ER), the history of the deregulation of the 

previously regulated electric supply market in the ERCOT region began in 1995, when the 

Texas Legislature passed Senate Bill 373, introducing wholesale competition into Texas’ 

intrastate market. PUCT adopted rules requiring all transmission system owners to make their 

transmission systems available for use by others at prices and on terms comparable to each 

respective owner’s use of its system for its own wholesale transactions. In 1999, by terms of 

Senate Bill 7, choice was further broadened by allowing retail customers of investor owned 

utilities (IOUs) to choose their electric energy supplier (electric cooperatives and municipally 

owned utilities such as CPS Energy had the option not to allow their retail customers to join this 

arrangement and CPS Energy has not allowed this). Formerly, vertically integrated IOUs had to 

separate their retail energy service activities from regulated utility activities and to unbundle their 

generation, transmission/distribution, and retail electric sales functions into separate units, 

which could be sold off or else operated as independent entities at arm’s length from each 

other. Transmission and distribution entities (including electric cooperatives and integrated 

municipally owned utilities) are fully regulated by the PUCT and must make their facilities 

available on an open and non-discriminatory basis. IOUs and independent power producers 

owning generation assets must be registered as power generation companies with the PUCT 
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NUREG-1937 8-4 February 2011 

and must comply with certain rules that are intended to protect consumers, but they are 

otherwise unregulated and may sell electricity in private bilateral transactions and at market 

prices (STPNOC 2010). 

As explained in the ER and confirmed in the references below, under deregulation in Texas, 

utilities no longer perform the comprehensive analysis and planning functions that they once 

did. The central planning organization under the new Texas market is the ERCOT ISO. State 

law assigns these obligations to ERCOT, under the oversight of the PUCT. The analyses, 

reports, system planning processes, and criteria development from ERCOT are the key 

measures for determining resource needs in the State (see e.g., Texas Utility Code Sections 

39.155(b) and 39.904(k)). STPNOC is relying upon several studies performed for or by ERCOT 

on need for power in ERCOT’s capacity as a regional transmission organization. Regional 

transmission organizations were created as a result of Order No. 2000 issued by the Federal 

Energy Regulatory Commission (FERC), which encouraged the voluntary formation of such 

organizations to administer the transmission grid on a regional basis throughout North America 

(FERC 1999, 2008). 

The ERCOT ISO region is also the geographic territory of the Texas Regional Entity (Texas RE) 

(now Texas Reliability Entity) (ERCOT 2008f). Texas RE is one of the eight approved regional 

entities in North America under the North American Electric Reliability Corporation (NERC). 

NERC’s mission is to ensure the reliability of the bulk power system in North America. NERC 

develops and enforces reliability standards, monitors the bulk power system, assesses and 

reports on future transmission and generation adequacy, and offers education and certification 

programs to utility industry personnel (NERC 2008a). Texas RE is a functionally independent 

division of ERCOT and is independent of all users, owners, and operators of the bulk power 

system in the State of Texas. As mandated by the delegation agreement with NERC approved 

by FERC, Texas RE performs the regional entity functions described in the Energy Policy Act of 

2005 for the ERCOT region. Texas RE develops, monitors, assesses, and enforces NERC 

reliability standards within the ERCOT region. In addition, Texas RE has been authorized by 

the PUCT and is permitted by NERC to investigate compliance with the ERCOT protocols and 

operating guides, working with PUCT staff regarding any potential protocol violations (ERCOT 

2008f). 

The ERCOT region is almost entirely isolated from other NERC regions, electrically speaking. 

The formation of what is now the ERCOT region dates from the beginning of World War II, when 

several Texas utilities banded together and interconnected to support the war effort as the 

Texas Interconnected System (STPNOC 2010). Texas Interconnected System formed ERCOT 

in 1970 to comply with NERC requirements (ERCOT 2008c). Since the goals of these entities 

over the years have been to ensure the reliability of the Texas grid rather than to interconnect 

with the rest of the country, importing electric power into, or exporting electric power out of the 

ERCOT region effectively is not practicable. As a practical matter this means that electricity 
Need For Power 

February 2011 8-5 NUREG-1937 

demand in the ERCOT region must be served from generation within ERCOT and that power 

generated in excess of demand within ERCOT cannot effectively reach other markets 

(STPNOC 2010). 

8.1.3 Description of the ERCOT Analytical Process 

NRC guidance provides that additional independent review by the NRC may not be needed 

when need for power analyses prepared by an independent third party such as an affected 

state, NERC reliability council, or regional transmission organization is sufficiently 

(1) systematic, (2) comprehensive, (3) subject to confirmation, and (4) responsive to forecasting 

uncertainty (NRC 2000). Taken in aggregate, the review team determined that the studies and 

reports summarized in Section 8.4 satisfy the four tests. 

8.1.3.1 Systematic Test 

The review team determined ERCOT has a systematic and iterative process for load forecasting 

and reliability assessment that is updated annually. ERCOT is required by the PUCT to provide 

extensive studies, issue reports, make recommendations for transmission system needs and 

resource adequacy, and even make legislative recommendations to further those objectives 

(STPNOC 2010). The essence of ERCOT is that it is a neutral and independent source of 

information on electricity issues for policymakers. The development of these reports is subject 

to a vigorous stakeholder input process. 

Membership in ERCOT is open to any entity that meets any of the segment definitions as set 

forth in the ERCOT bylaws. Members must be in an organization that either operates in the 

ERCOT region or represents consumers within the ERCOT region. The members are 

organized by the following market segments: consumers, cooperatives, independent 

generators, independent power marketers, independent retail electric providers, investor owned 

utilities, and municipal utilities (ERCOT 2005b, 2008i). ERCOT uses industry best practices and 

methodological approaches to determine future system reliability and the need for new 

generating capacity. The forecasts and methods are vetted by ERCOT membership. 

Moreover, the analyses and actions of ERCOT based on these analyses are overseen by the 

PUCT. 

8.1.3.2 Comprehensive Test 

The review team finds that, in aggregate, the ERCOT studies and reports discussed in 

Section 8.4 are comprehensive. ERCOT (ERCOT 2010a) takes account of trends in customer 

demand (including the underlying factors of population, income, and employment growth and 

impacts of both normal and extreme weather conditions). The electricity supply analysis takes 

into account changes in generation profile and potential generation additions; new generating 
Need For Power 

NUREG-1937 8-6 February 2011 

resources planned for construction in Texas; trends in electric power generation by fuel source; 

trends in consumption by class of consumer; forecasts of future electricity sales; transmission 

congestion in Texas; demand side management (DSM), demand response, and distributed 

generation; and electric reliability assessments. The demand forecasts are fed into the 

generation and transmission planning process. ERCOT uses industry best practices and 

methodological approaches to determine system reliability and the need for new generating 

capacity (ERCOT 2008e, g, 2010a, b). Moreover, the forecasts are subject to a vigorous 

participatory process. 

The model developers recognize that they have not been successful in the past in including 

electricity prices as valid predictive variables in the electricity demand model (ERCOT 2010a): 

Besides hourly load, ERCOT also secures weather data, economic and 

demographic data from outside providers. In regard to prices, which are 

considered an important driver for inclusion in a demand equation, it is not clear 

as to whether the wholesale prices that ERCOT collects are really the most 

relevant for a forecasting application, in terms of being the prices ultimately faced 

by the consumer. Since the wholesale prices are collected on an hourly basis, 

and retail prices are better reflected by an average over a longer time period, 

such as a month, wholesale hourly prices do not capture the correlation with the 

MWh consumption correctly. Several attempts to include market clearing prices 

of energy (MCPEs) in the forecasting models were made but were unsuccessful. 

The models obtained showed price to be insignificant or to indicate a nonsensical 

relationship regarding the direction of the effect of price (wrong sign on the 

coefficient) and thus should not be included in a long-term demand equation. To 

make matters more challenging in this respect, an objective and credible forecast 

of these prices would represent a major accomplishment in itself. Inclusion of a 

price variable in the forecasting models could potentially provide a means to 

calculate an unbiased and credible forecast of the price effect on the long-term 

load response. 

8.1.3.3 Subject to Confirmation Test 

The review team finds that, in aggregate, the studies and reports discussed in Section 8.4 are 

subject to confirmation. ERCOT’s forecasts are independently prepared. These forecasts are 

then independently reviewed, confirmed, and consolidated by PUCT and NERC. Both the LongTerm Peak Demand study (ERCOT 2010a) and the Capacity, Demand, and Reserves (CDR) 

Report (ERCOT 2010b) look at historical information as a check on past forecasting performance 

and these results are published. For example, in 2008 to validate the forecast model, an out-ofsample prediction was performed by estimating the model with data up to December 2005 and a 

forecast was produced for January 2006 to December 2006 using the actual temperatures. A 
Need For Power 

February 2011 8-7 NUREG-1937 

forecast for the summer season only was also produced using the actual temperatures. The 

system peak that occurred on August 17, 2006, was forecasted for the year 2006 with a 

0.78 percent error and a 0.45 percent error for the summer alone (ERCOT 2008d). Forecast 

comparisons for 2008 show a -0.5 percent error for annual energy (with monthly errors from 

-7.6 percent to plus 6.0 percent). Maximum hourly demand at the August peak had a 

-1.0 percent error and the forecast for annual peak had a -4.2 percent error (ERCOT 2008d) 

Over a longer term, from 1999 to 2006, the ERCOT peak demand and energy consumption 

forecasts were within ± 5 percent of the actual values (STPNOC 2010). ERCOT publishes its 

methodology, key input data, forecast errors, methodological uncertainties and limitations, and 

conclusions. 

8.1.3.4 Responsive to Forecasting Uncertainty Test 

In preparing its load forecasts and reliability assessments, ERCOT takes account of forecasting 

uncertainty. For example, ERCOT’s process carefully considers the effects of weather 

(especially temperature) uncertainty on the demand for electricity and on the reserve margin 

(ERCOT 2010a), as described in Section 8.2. Because of the variability of wind and the 

increasing reliance on wind power in Texas, ERCOT is also adopting improved wind forecasting 

tools (ERCOT 2010c). Additionally, ERCOT takes into account the fact that not all proposed 

new generating units will be built and that some existing generating units may be taken offline 

for various reasons. 

8.1.3.5 Summary of ERCOT Analytical Process 

Based on its review of ERCOT documents, the review team determined that, in aggregate, the 

ERCOT forecasts and documents are sufficiently (1) systematic, (2) comprehensive, (3) subject 

to confirmation, and (4) responsive to forecasting uncertainty to serve the needs of the review 

team in complying with Section 102 of the National Environmental Policy Act. In keeping with 

the ESRP (NRC 2000), NRC Staff Memorandum (NRC 2010), and the Commission statements 

at 68 FR 55910, the review team gave particular credence to: 

• ERCOT’s 2010 long-term demand forecast (ERCOT 2010a), 

• ERCOT’s 2010 CDR Report and winter 2010 update (ERCOT 2010b, e), 

• ERCOT’s examination of long-term generation issues associated with wind energy in the 

2008 Long-Term System Assessment (ERCOT 2008e), and 

• NERC’s evaluation of long term system adequacy (NERC 2008b). 
Need For Power 

NUREG-1937 8-8 February 2011 

8.2 Power Demand 

The review team initially relied on the 2007 ERCOT Long-Term Peak Demand and Energy 

Forecast as its basis for understanding the need for power (ERCOT 2007). Since then, the 

review team also has reviewed the 2008, 2009, and 2010 long-term demand studies (ERCOT 

2008d, 2009a, 2010a), ERCOT’s 2008 Long Term System Assessment study (ERCOT 2008e), 

ERCOT’s latest CDR reports (ERCOT 2009b, 2010b, e), and the summary of ERCOT findings 

from the 2008 studies in NERC’s 2008 Long-Term Reliability Assessment (NERC 2008b) as 

bases for comparison with STPNOC’s need for power assessment (STPNOC 2010). ERCOT’s 

demand forecasting model is described in detail in the 2010 demand forecast report and is 

summarized below (ERCOT 2010a). 

The ERCOT long-term load forecast covers a period from 1 to 15 years using a process and 

tools developed internally by ERCOT. The forecast is used for a variety of operating and 

planning purposes, the most important of which for this EIS is system planning. The forecasting 

model is a set of equations that describes the historical load as a function of independent 

variables, where the coefficients are estimated by multiple regression methods. The long-term 

forecast was produced with a set of econometric models that use weather and economic and 

demographic data to capture and project the long-term trends from the past 5 years of historical 

data. Fifteen years of weather data were available from DTN Meteorologix for 20 ERCOT 

weather stations. These weather stations were used to develop weighted hourly weather 

profiles for each of eight weather zones in the ERCOT region. These data were used in the 

load shape models. Monthly cooling degree days and heating degree days were used in the 

monthly energy models. Uncertainty in weather effects (especially that of extreme weather) on 

load was investigated in a number of ways, including the running of Monte Carlo simulations, to 

assess the impact of extreme temperatures on the peak demands. Economic and demographic 

changes can affect the characteristics of electrical demand in the medium- to the long-run. 

Economic and demographic data at the county level were obtained by ERCOT on a monthly 

basis from Moody’s Economy.com. Three of the key economic and demographic variables that 

drive the forecast are per capita income, population, and employment. The growth rates in 

these variables have declined during the last three forecasts, but still show largely the same 

picture for need for power over the next 10 to 15 years. 

Because the proposed Units 3 and 4 at the STP site would be baseload merchant power plants 

that are expected to operate more than 90 percent of the time to obtain best cost-effectiveness, 

the most important part of the ERCOT forecast for purposes of this review is the growth in 

annual energy demand and the growth in demand at the near-minimum demand hours, since 

Units 3 and 4 would address this lowest part of the annual load duration curve. ERCOT, on the 

other hand, needs to emphasize peak load demand because of its institutional responsibility for 

meeting peak demand and reserve margin. During the period from 2002 to 2009 the compound 

growth rates for peak demand and annual energy were 1.77 percent per year and 1.32 percent 
Need For Power 

February 2011 8-9 NUREG-1937 

per year, respectively (ERCOT 2010a). Assuming normal weather, and accommodating the 

adverse effects of the slow recovery from the recent recession, ERCOT projects that peak 

energy demand would increase at a compounded rate of 1.72 percent per year (10,657 MW 

total) between 2010 and 2019 and that annual energy (average demand) would grow at a 

compounded growth rate of 1.74 percent per year (5928 average MW total) (ERCOT 2010a). 

Figure 8-2 shows the ERCOT 2010 peak and annual average load forecasts for the period 2010 

through 2019. 

35,439 36,096 36,998 37,784 38,421 39,040 39,643 40,250 40,829 41,367 

64,052 65,206 66,658 68,265 69,451 70,517 71,736 72,630 73,656 74,709 

-

10,000 

20,000 

30,000 

40,000 

50,000 

60,000 

70,000 

80,000 

2010 2011 2012 2013 2014 2015 2016 2017 2018 2019

MW

Years

Average Load Growth System Peak Demand Growth

Figure 8-2. Peak Demand and Average Demand in the ERCOT Region 2010-2019 

(ERCOT 2010a) (Note: Figures are projected totals, not annual growth.) 

Figure 8-3 shows the 8760-hour load duration curve for the ERCOT region for 2009, the last full 

year for which data were available. The load duration curve can be used to approximately 

identify the need for baseload power plants. Baseload power demand is approximately the 

minimum demand of the system and (while regions vary) typically is about 35 percent to 

40 percent of peak demand (Progress Arkansas 2010, Cordaro 2008). Baseload plants (usually 

coal-fired, nuclear, or hydroelectric) address this minimum demand and operate almost 
Need For Power 

NUREG-1937 8-10 February 2011 

continuously (about 70 to 80 percent of the time), except when down for maintenance, repairs, 

or forced outages (DOE/EIA 2011, PSC-Wisconsin 2009).

0

10000

20000

30000

40000

50000

60000

70000

1 501 1001 1501 2001 2501 3001 3501 4001 4501 5001 5501 6001 6501 7001 7501 8001 8501

MW

Hours

Figure 8-3. ERCOT 2009 Load Duration Curve. (Compiled by review team from ERCOT 2009c) 

Approximating minimum or baseload demand in the ERCOT region by the demand that prevails 

at least 80 percent of the hours in the year (7008 hours) (ERCOT 2008e) equals a demand of 

28,215 MW in 2009, which was about 44 percent of peak demand in the ERCOT region in 2009. 

This is the portion of demand that is addressed by existing nuclear power units at STP and 

Comanche Peak (as well as some hydroelectric, coal, and natural gas combined cycle 

baseload). If absolute minimum annual hourly demand (equal to 21,348 MW in 2009) and 80th 

percentile hourly demand both grew at approximately the rate of annual average hourly demand 

in the ERCOT region shown in Figure 8-2, they both would grow by about 16.7 percent by 2019, 

or by amounts of 3565 MW and 4712 MW, respectively. These increases exceed the increase 

of high-availability baseload capacity represented by proposed Units 3 and 4 at STP. This 

simple calculation provides an initial indication that the growth in baseload demand in the 

ERCOT region would be enough to support additions of two units at both STP and Comanche 

Peak. 
Need For Power 

February 2011 8-11 NUREG-1937 

In the 2008 annual NERC report ”2008 Long-Term Reliability Assessment 2008-2017, October 

2008” (NERC 2008b), it is noted that forecasts of the demand for power declined between the 

2007 and 2008 forecasts (after having risen between 2006 and 2007). The decline continued 

from 2008 to 2010, as Texas had a slower-than-expected recovery from the 2008-2009 

recession. Figure 8-4 shows the last five summer peak load forecasts compiled by ERCOT. 

Figure 8-5 shows the difference between annual energy forecasts in 2009 and 2010. The actual 

2009 values are very close to the 2009 forecast. This is slightly misleading because the peak 

forecast assumes normal summer weather, and weather was relatively hot on the peak day in 

2009. 

60,037 60,210 

62,339 

63,794 

65,135 

66,508 

67,955 

69,456 

70,733 

72,394 

73,998 

75,596 

77,024 

78,694 

80,161 

58,507 

62,179 62,188 

63,400 

56,086

64,052

65,206

66,658

68,265

69,451

70,517

71,376

72,630

73,656

74,709

50,000 

55,000 

60,000 

65,000 

70,000 

75,000 

80,000 

85,000 

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019

MW

Years

2006 Forecast

2007 Forecast

2008 Forecast

2009 Forecast

2010 Forecast

Figure 8-4. ERCOT 2006, 2007, 2008, 2009, and 2010 Peak Load Forecasts. 

(Compiled by review team from ERCOT 2007, 2008d, 2009a, 2010a)
Need For Power 

NUREG-1937 8-12 February 2011 

Figure 8-5. ERCOT 2009 and 2010 Energy Demand Forecasts (ERCOT 2010a)

The NERC report (NERC 2008b) for ERCOT stated that the 2008 forecast, which is lower than 

that used by STPNOC, takes into account the slowing of the Texas economy: 

• The lower peak demands reflect the expected state of the economy as represented by 

economic indicators that have been found to drive electricity use in the ERCOT region’s 

eight weather zones, including real per-capita personal income, population, gross 

domestic product, and various employment measures including non-farm employment 

and total employment. 

• In the long-term, real personal per-capita income is expected to level-off or decline in a 

slight to medium fashion due to wage rates experiencing modest growth, only slightly 

faster than inflation, due to lower productivity growth. Texas non-farm employment 

continues to grow faster than the U.S. rate. The gross domestic product also shows a 

lower level and growth rate from 2008 to 2018 when compared to last year’s forecast. 

• Given the net effects of the economic indicators used in the 2008 Long Term Demand 

Forecast, they indicate slowdown of the economy in the long run. The long-run impact 

on the forecast due to economic slowdown is projected to start around 2010. Its effects 

are projected to translate into a 4.50 percent decline in energy and a 3.31 percent 

decline in peak demand by 2018, when compared to last year’s forecast [Note: “last 

year” in the quote refers to the 2007 forecast]. 

281 285 289 299 306 308 312

308 310 316 324 331 337 342 347 353 358 362

312 315 322 333 342 349 356 363 370 376 382

0

50

100

150

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300

350

400

450

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019

TWh

Year

Historical 2010 Forecast 2009 Forecast
Need For Power 

February 2011 8-13 NUREG-1937 

The review team notes that the ERCOT 2009 and 2010 forecasts feature still further reduced 

economic growth in the short term as a result of the 2008-2009 economic downturn. Figure 8-6 

through Figure 8-8 show the change in key long-term growth variables used as the primary 

economic drivers for the 2009 ERCOT forecasts: population, employment, and per-capita 

income. ERCOT determined population growth rate would be relatively unchanged due to the 

economic downturn following an initial drop in numbers, but that employment and per-capita 

income would suffer an initial slump, followed by a faster growth rate in 2008 that would 

overtake the 2008 forecasted values by about 2013. 

Figure 8-6. Population in the ERCOT Region (ERCOT 2009a) 
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NUREG-1937 8-14 February 2011 

Figure 8-7. Total Non-Farm Employment in the ERCOT Region (ERCOT 2009a)

Figure 8-8. Per Capita Income in the ERCOT Region (ERCOT 2009a)
Need For Power 

February 2011 8-15 NUREG-1937 

Although ERCOT did not provide figures comparable to Figures 8-6 through 8-8 in its 2010 

forecast report, ERCOT did comment that the recession has been having a continuing impact 

that has affected the long-term forecasted need for power. The 2010 ERCOT forecast (ERCOT 

2010a) addresses the impact of the recession, in comparison with the 2009 forecast, with the 

following explanation: 

• Due to the sluggish recovery reflected in the economic forecast, the nine-year growth rate 

for 2010 through 2019 is 1.72 percent compared to last year’s (2009’s) long-term demand 

energy forecast of 2.00 percent growth rate for 2009 through 2019. 

• The key factor driving the lower peak demands and energy consumption (MWh), in 

comparison to the 2009 long-term demand energy forecast, is the overall outlook of the 

economy, as measured by economic indicators such as the real per capita personal income, 

population, gross domestic product, and various employment measures including non-farm 

employment and total employment. The model was also recalibrated to include the effects 

of having an additional year of historical load data. 

Because it is involved in meeting the maximum demand conditions in its territory, ERCOT pays 

considerable attention to the summer peak demand and the margin of safety in meeting that 

peak. The current generation reserve margin in the ERCOT region is now 13.75 percent (it was 

12.5 percent through 2010), as a result of actions taken by the ERCOT Board of Directors on 

November 16, 2010 (ERCOT 2010d). 

The following is a brief summary of the methodology for the reserve margin calculation (ERCOT 

2005a). The terms used here are defined below. 

Firm Load equals: 

• long-term forecast model total summer peak demand 

• minus loads acting as resources serving as responsive reserve 

• minus loads acting as resources serving as non-spinning reserve 

• minus balancing up loads. 

Available Resources equals: 

• installed capacity using the summer net dependable capability pursuant to ERCOT testing 

requirements (excluding wind generation) 

• plus capacity from private networks 
Need For Power 

NUREG-1937 8-16 February 2011 

• plus effective load carrying capability (ELCC) of wind (determined in a study for ERCOT in 

2006 by Global Energy to be 8.7 percent of name plate generation [GED 2007] and 

reaffirmed at ERCOT’s Board of Directors meeting on November 16, 2010 [ERCOT 2010d]) 

• plus reliability must run units under contract 

• plus 50 percent of non-synchronous ties 

• plus summer net dependable capability of available switchable capacity as reported by the 

owners 

• plus available “mothballed” generation 

• plus planned generation with a signed generation interconnection agreement (SGIA) and a 

Texas Commission on Environmental Quality air permit, if required 

• plus ELCC of planned wind generation with SGIA 

• minus retiring units. 

Reserve margin is then defined as (Available Resources - Firm Load Forecast/Firm Load 

Forecast). 

In the ERCOT methodology, loads acting as resources are capable of reducing or increasing 

the need for electrical energy or providing ancillary services such as responsive reserve service 

or non-spinning reserve service. Loads acting as resources must be registered and qualified by 

ERCOT, and they will be scheduled by a qualified scheduling entity (STPNOC 2010). 

STPNOC discussed the need for power in the context of declining reserve margins in the 

ERCOT region (STPNOC 2010). As recently as May 2008, forecasted reserve margin in the 

ERCOT CDR Report was expected to fall below the old required reserve margin of 12.5 percent 

by 2013. However, the May 2010 and December 2010 updates to this report now show a better 

capability to meet firm load at least through 2015 (see Table 8-1). ERCOT produces a “topdown” forecast for its major subareas, but does not include separate demand estimates for 

different end-use sectors. Thus, forecasts do not contain separate forecasts for residential, 

commercial, and industrial demand. 

As shown in Table 8-1, the ERCOT 2010 forecasts took into account the impact of existing DSM 

programs and efficiency programs not otherwise accounted for in its econometric forecast. As 

stated in the 2008 Texas State Energy Plan, DSM can be divided into (1) demand-response 

programs, which are designed to encourage customers to reduce usage during peak times or to 

shift that usage to other times; and (2) energy efficiency programs, which provide a reduction in 

the overall quantity of electricity consumed over the year, but may not necessarily reduce the 

electricity demanded at the hour of system peak (Governor’s Competitiveness Council 2008). 

Under PUCT regulations, regulated utilities (transmission and distribution utilities) in ERCOT, 
Need For Power 

February 2011 8-17 NUREG-1937 

and the integrated utilities outside of ERCOT, are required to offer DSM programs sufficient to 

offset 20 percent of load growth in 2010 and 2011, 25 percent in 2012, and 30 percent in 2013 

and thereafter (Texas Register 2010a). In recent years the goal was the same 20 percent as for 

2010 and 2011. Thus, the new regulations add 5 percentage points to the goals of the required 

programs in 2012 and 10 percentage points to the required goals for 2013 and after. Although 

only regulated utilities are affected inside of ERCOT, success of such programs could affect the 

overall demand for electricity in the ERCOT region. 

Table 8-1. ERCOT Peak Demand and Calculated Reserve Margin, 2010-2015

 2010 2011 2012 2013 2014 2015 

Total Summer Peak Demand,MW 64,052 65,206 66,658 68,265 69,451 70,517 

Less: LAARS Serving as Response 

Reserve and Spinning Reserve, 

Balancing–Up Loads 

1062 1062 1062 1062 1062 1062 

Less Emergency Interruptible Load 

Service 

336 370 407 447 492 541 

Less Energy Efficiency Program 

(per House Bill 3693) 

242 242 242 242 242 242 

Firm Load Forecast, MW 62,412 63,532 64,947 66,514 67,655 68,672 

Required Reserve Margin (12.5% in 

2010,13.75% after 2010) 

7802 8736 8930 9146 9303 9442 

Required Resources 70,214 72,268 73,877 75,660 76,958 78,114 

Estimated Total Resources, MW 

(Table 8-3) 

75,755 73,657 75,196 75,253 77,449 78,245 

Reserve Margin ((Resources - Firm 

Load Forecast)/Firm Load Forecast) 

21.4% 15.9% 15.8% 13.1% 14.5% 13.9% 

Sources: ERCOT 2010b, e 

LAAR = Loads Acting as Resources

 

Table 8-2 is a less-detailed extension of Table 8-1 to the year 2025 that shows the ERCOT 

2010 forecast of demand and reserve margin (ERCOT calculated long-term required resources 

to meet peak demand plus 13.75 percent after 2010). There are a number of additional 

aggressive energy efficiency programs being considered in Texas during 2010 that are not 

considered in the ERCOT forecast methodology or in the need for power analysis because they 

are not Texas law, regulation, or policy. There are a number of other emerging programs, 

however, for which there is not enough performance information available to determine their 

quantitative effect on even the most recent ERCOT forecast. 
Need For Power 

NUREG-1937 8-18 February 2011 

Table 8-2. Calculated ERCOT Reserve Margin, 2009-2025

 2009 2010 2015 2020 2025 

Peak Summer Demand, MW 63,400 64,052 70,517 75,762 79,858 

Less: LAAR Spinning and Non Spinning 

reserve, Emergency Interruptible Load Service, 

Balancing-Up Loads, and Energy Efficiency 

Programs 

1561 1640 1845 1899 1899 

Firm Load, MW 61,839 62,412 68,672 73,863 77,959 

Plus Reserve Requirements (Firm Load plus 

12.5% in 2009-2010, Firm Load plus 13.75% 

after 2010) 7730 7802 9442 10,156 10,719 

Total Resource Requirements, MW 69,569 70,214 78,114 84,019 88,678 

Total Resources, No Retirements 72,712 75,755 78,245 78,905 78,905 

Reserve Margin Based on Firm Load 17.6% 21.4% 13.9% 6.8% 1.21% 

Sources: 1) For years 2009-2015, ERCOT 2010b,e; 2) Years 2020-2025 calculated by the review team from tables 

and figures in ERCOT 2010b,e (see Table 8-3). 

The American Recovery and Reinvestment Act of 2009 (ARRA) has provided substantial 

temporary funding for many energy conservation programs in Texas, as described by the Texas 

State Energy Conservation Office (SECO) (SECO 2010). Funded programs included the 

Building Efficiency and Retrofit Program ($134.5 million), the Energy Efficiency and Conversion 

Block Grants ($45.6 million to the State, $163 million directly to Texas cities and counties), and 

the Energy Efficient Appliance Rebate Program ($23.3 million). It also added almost $327 

million to the Weatherization Assistance Program of the Texas Department of Housing and 

Community Affairs (TDHCA) (TDHCA 2010). Texas has its own in-state programs, including the 

LoanStar revolving loan program for public buildings. During the 2009 legislative session, the 

Texas legislature passed and the Governor signed HB 1937, which allows municipalities to 

begin loan programs for retrofits of existing buildings and recover the cost through a contractual 

assessment on the property (Property-Assessed Clean Energy or PACE program) (Texas 

Legislature Online 2010). In addition, SECO adopted rules implementing the 2009 International 

Energy Conservation Code and 2009 International Residential Code as the basis for building 

codes for single family and other residential housing throughout the State, effective April 1, 2011 

and January 1, 2012, respectively (Texas Register 2010b). Some Texas municipal utilities that 

are in the ERCOT region but not directly regulated by the State are ahead of this schedule and 

some have a range of active energy conservation programs that have already saved significant 

amounts of electricity locally and project to save significantly more by 2020 (e.g., Austin [Austin 

Energy 2010] and San Antonio [CPS Energy 2010]). 

Despite all of this activity, it is not clear from available documentation what effect the inclusion of 

these programs would have on the 2010 ERCOT forecast. Many of the programs address the 
Need For Power 

February 2011 8-19 NUREG-1937 

same end uses or represent the continuation of long-term program improvements whose effects 

are expected to be captured in the econometric modeling. The optimism that available energy 

efficiency resources in Texas have generated must be balanced against the realization that 

some of the programs are cost-capped (e.g., PUCT’s utility program), that others are temporary 

(ARRA), that all eventually will face increasing costs and greater difficulties as easier energy 

savings are found and captured, and that new energy services will be found and take-back and 

rebound effects will reduce the net energy savings. Based on review team discussions with 

ERCOT staff (Scott 2010) and extensive examination of Texas public documents and websites, 

the review team concluded that while there may be some long-range impacts resulting from 

these programs not currently captured by the ERCOT models, there is almost no currently 

available, reliable information that suggests the impacts of these programs have been 

significant on a statewide basis or that they require a significant adjustment to the ERCOT 

forecasts. They are not included in Table 8-2. A portion of their possible effect is included in 

the review team’s sensitivity tests depicted in Table 8-5. 

Total resources estimates and the need for baseload power are calculated in Section 8.3. The 

total resources estimate does not include STP Units 3 and 4 or other units projected for 

completion after 2014. 

8.3 Power Supply 

ERCOT prepares an annual CDR Report and updates (ERCOT 2010b, e) on the supply 

capacity, demand, and reserves in the ERCOT region. It is developed from data provided by 

the market participants as part of the annual load data request, the generation asset 

registrations, and from data collected for the annual U.S. Department of Energy Coordinated 

Bulk Power Supply Program Report. The working paper calculates the generation resources 

reported to be available by market participants (STPNOC 2010). 

The CDR Report considers all of the generation resources in the ERCOT region meeting the list 

in the previous section. There are several constraints on which resources are listed as available 

in the CDR Report. 

• Only those new generating resources for which the owners have initiated full transmission 

interconnection study requests through ERCOT are included as planned generation. 

• If an air permit is required for a new generating unit, the unit must have received that permit 

before it is included as planned generation. 

• Some mothballed resources may be counted, but the probability of these resources being 

able to be returned to service varies by generating technology and declines as the length of 

time they are mothballed increases (ERCOT 2005b). 

• Retiring and retired units are not counted. 
Need For Power 

NUREG-1937 8-20 February 2011 

Wind Energy in Texas

Large amounts of wind energy have or are about to enter the ERCOT region. In the Interim 

Order on Reconsideration in Docket 33672 (Interim Order), the PUCT designated five zones as 

Competitive Renewable Energy Zones (CREZ), primarily for wind power, in the western and 

Panhandle areas of Texas. By Texas law this amount of power would have to be accepted by 

the market, if offered to the market, in preference to thermal generation. Installed wind capacity 

could grow from around 9115 MW early in 2010 (ELCC of 793 MW) to as much as 24,400 MW 

(ELCC of 2123 MW) over the next few years, with a planning value of 18,456 MW (ELCC of 

1606 MW) in 2018. In response, ERCOT performed a CREZ Transmission Optimization Study 

(ERCOT 2008h), an extensive study of intrastate transmission bottlenecks that might arise and 

solutions that might be needed to absorb this new power source. 

The wind generation development scenarios used in the CREZ Transmission Optimization 

Study were also used to evaluate resource needs in the ERCOT system in the December 2008 

Long-Term System Assessment (ERCOT 2008e). The Long-Term System Assessment 

evaluated the need for other types of generation capacity under the assumption that the 

projected 2018 load duration curve would be lowered by the maximum possible use of 

18,456 MW of wind energy. Figure 8-9 shows that at approximately the 80th percentile (a ruleof-thumb definition of baseload generation) there would still be a demand for up to 30,852 MW 

of baseload with 18,456 MW of wind generation installed in the system if natural gas prices 

remained at about $7 per million Btu. The 80th percentile of the 2009 load duration curve for 

ERCOT (Figure 8-3) is 28,215 MW. If the demand for power at the 80th percentile expanded at 

about the ERCOT 2010 projected rate (Figure 8-2) until 2018 and the ELCC of 18,456 MW of 

wind (1606 MW) were then subtracted, the approximate need for baseload power other than 

wind would be 31,146 MW (32,752 MW minus 1606 MW), implying an increased need for about 

2900 MW of baseload power other than wind by 2018. 

U.S. Energy Information Administration forecasts of natural gas prices favor a natural gas price 

to the electricity sector of about $7 per million Btu through much of the next 20 years, as many 

new resources come online, even as economic recovery increases demand (DOE/EIA 2009). 

This observation and the calculations in the previous paragraph indicate that the demand in 

2018 for baseload capacity (80th percentile of the wind-altered load duration curve) would be 

close to the 30,852 MW forecast in Figure 8-9. 
Need For Power 

February 2011 8-21 NUREG-1937 

Figure 8-9. ERCOT Net Load Duration Curve in 2018 with 18,456 MW of Wind Generation 

Capacity (ERCOT 2008e)

ERCOT’s 2010 Supply Forecast 

Table 8-3 provides ERCOT’s May 2010 projection of the generating resources of various types 

that would be available to serve the ERCOT region between 2010 and 2015 

(ERCOT 2010b, e, f), along with review team calculations of resources available in 2015 and 

2025 derived from ERCOT’s long-term forecasts (ERCOT 2010a). The 2010 through 2015 

ERCOT projections anticipate substantial development (about 4590 MW) of non-wind resources 

with signed interconnection agreements and air permits. The projections do not include STP 

Units 3 and 4, but do include 145 MW of biomass. About 72 percent of the new capacity would 

be natural gas-fired (ERCOT 2010b). ERCOT’s 2010 projections also anticipate substantial 

capacity (about 10,400 MW) of total wind generation being available by the end of the 2010 

through 2015 period, which was about the amount already in the system at the end of 2010 

(ERCOT 2010f), showing the forecast to be conservative. In consideration of the ambitious 

wind program in Texas and clear assumption by ERCOT and PUCT that more wind power will 

be developed in the long term, the review team tested the impact of wind development on 

ERCOT’s forecast by assuming that these resources would be further developed and would 

meet the State’s goal of 18,546 MW of installed wind capacity by 2020. If the State falls short of 

its goal for wind, the demand for STP Units 3 and 4 would be larger than calculated in this 

section. 
Need For Power 

NUREG-1937 8-22 February 2011 Table 8-3. ERCOT Region Forecasted Summer Resources, 2010-2025 ERCOT Forecast 2010-2015 Extended Forecast 2020-2025 2010 2011 2012 2013 2014 2015 2020 2025 Installed Capacity, MW 66,228 63,896 63,896 63,896 63,896 63,896 63,896 63,896 Capacity from Private Networks, MW 4803 4803 4803 4803 4803 4803 4803 4803 ELCC of Existing Wind Generation, MW 793 829 829 829 829 829 829 829 RMR Units to be under Contract, MW 688 0 0 0 0 0 0 0 Operational Generation, MW 72,512 69,528 69,528 69,528 69,528 69,528 69,528 69,528 50% of Non-Synchronous Ties, MW 553 553 553 553 553 553 553 553 Switchable Units, MW 2848 2962 2962 2962 2962 2962 2962 2962 Available Mothballed Generation, MW 0 191 223 239 255 271 271 271 Planned Units (not wind) with SIA and Air Permit, MW 0 740 1,895 1,895 4,055 4,835 5,495 5495 ELCC of Planned Wind Units with SIA, MW 0 0 35 76 96 96 96 96 Total Resources, MW 75,913 73,974 75,196 75,253 77,449 78,245 78,905 78,905 Less Switchable Units Unavailable to ERCOT, MW 158 317 0 0 0 0 0 0 Resources, MW (no retirements) 75,755 73,974 75,196 75,253 77,449 78,245 78,905 78,905 Firm Load Forecast 62,412 63,532 64,947 66,514 67,655 68,672 73,863 77,959 Reserve Margin Above Firm Load (no retirements) 21.4% 15.9% 15.8% 13.1% 14.5% 13.9% 6.8% 1.21% Additional Resources Needed, Reserve Margin 13.75% 

0

0 0 407

0

0 5115 9744

Resources, MW (with retirements) 75,755 73,974 75,196 75,253 77,449 72,122 66,468 58,520Reserve Margin Above Firm Load (with retirements) 

21.4% 15.9% 15.8% 13.1% 14.5% 5.0% -10.0% -24.9%

Additional Resources Needed, Reserve Margin 13.75% 

0

0 0 407

0 5993 17,551 30,158

Sources: ERCOT 2010b, e, f; review team calculations for extended forecast period. 
Need For Power 

February 2011 8-23 NUREG-1937 

There is uncertainty as to the timing, type, number, and capacity of generating units that may be 

retired during the forecast period, which affects the need for replacement generating plants. 

ERCOT’s forecast does not usually project any retirements because it only includes plants for 

which ERCOT has received official notice and the lead times for the retirements are only a few 

months. However, the forecast does show ERCOT’s forecasted generating capacity, less the 

capacity of plants 30, 40, and 50 years old that could be retired. The age of the power plant 

being considered for retirement is a factor in the decision to retire the plant. Based on ERCOT’s 

May 2010 CDR Report, shows how the summer capacity of generating resources may be 

affected by the need of some participants to retire the oldest (likely to be the least efficient or 

most polluting) power plants. The review team tested the impact of retirements. First the 

review team noted that after 2010, plants over 50 years old (the most conservative retirement 

assumption) could be retired based on age, cost, or for environmental reasons. Based on the 

May 2010 CDR Report (ERCOT 2010b) and the ERCOT 2010 Long-Term System Assessment 

(ERCOT 2010f), the review team estimated that a cumulative 6123 MW of capacity would be 

from plants at least 50 years old and that could be retired by 2015 and a cumulative 12,437 MW 

would be from plants at least 50 years old and that could be retired by 2020. These numbers 

are supported in part by a 2010 NERC study that concluded 5300 to 5800 MW of (mostly coal) 

generating capacity in the ERCOT region would be de-rated or retired by 2015 in response to 

more stringent environmental regulations (NERC 2010). Since ERCOT did not include any 

retirements in its forecast, under any retirement scenario the replacement of retiring power 

plants in the ERCOT region adds to the need for new generating capacity. 

The ERCOT forecast of generating resources shown in Table 8-3 begins with installed capacity 

of existing generating stations. ERCOT only produces a detailed forecast through the year 

2015, but does provide a less-detailed estimate of peak demand through the year 2025. 

Because STP Units 3 and 4 would come online between 2015 and 2020, in Table 8-3 the review 

team extended the assumptions made by ERCOT through 2015 to the post-2015 period. 

ERCOT added generating capacity of private networks (connected to the ERCOT grid, but not 

directly metered by ERCOT), the ELCC of existing wind generators (at 8.7 percent of installed 

capacity), and reliability must-run (RMR) units that are required for local grid stability. The 

remaining group of resources includes (1) 50 percent of non-synchronous ties, (2) so-called 

“switchable” resources that could either operate in ERCOT or in the Southwest Power Pool; (3) 

a protected estimate of mothballed resources that could be brought back on line in each year 

(the actual estimate is an expected value based on detailed computations that involve the age 

of the unit and the length of time it has been shut down), and (4) planned resources, whose 

inclusion depends on the phase that each resource is in the required interconnection studies 

(STPNOC 2010). ERCOT adjusted this resulting estimate downward to account for switchable 

units known to be unavailable to ERCOT and retiring units. 
Need For Power 

NUREG-1937 8-24 February 2011 

78,114 

84,713 

90,838 

97,113 

68,672 

74,473 

79,858 

85,374 

72,122 

66,468 57,860 

46,207 

57,860 

46,207 44,600 

31,816 

44,600 

31,816 

28,100 26,248 

20,000 

30,000 

40,000 

50,000 

60,000 

70,000 

80,000 

90,000 

100,000 

110,000 

120,000 

2015 2020 2025 2030

MW

Year

ERCOT Generation Capacity and Demand Projections

Total Requirements +13.75% Reserve Margin

Peak Demand (Firm Load)

Capacity less units 50 years old or older 

Capacity less units 40 years old or older 

Capacity less units 30 years old or older 

Figure 8-10. Alternative ERCOT Generation Capacity Reduction Scenarios vs. Projected 

Demand (ERCOT 2010b) 

The review team extended all of these elements through 2025, as shown in Table 8-3. 

Table 8-3 shows that, even given the ERCOT Board of Director’s November 2010 decision to 

raise the target reserve margin to 13.75 percent (ERCOT 2010d), the percent reserve margin 

was met in the ERCOT forecast in 2015. However, the review team’s extension of the ERCOT 

forecast to 2020 based on ERCOT’s 2020 peak load forecast shows that more than 5100 MW of 

additional generation would be needed by 2020 to meet the target reserve margin. With 

retirements, 6000 MW of additional generation would be needed as early as 2015 and over 

17,500 additional MW would be needed before 2020. ERCOT does not specify how much 

would need to be baseload power. 

STPNOC conducted its need for power assessment in 2007 and did not update it as later 

ERCOT forecasts became available. STPNOC concluded in its ER (STPNOC 2010), based on 

the ERCOT 2007 forecasts and before the 2008-2009 economic recession, that the total 

generation shortage in 2016 could be between 20,000 and 50,000 MW (including retirements). 
Need For Power 

February 2011 8-25 NUREG-1937 

In Table 8-3, the shortage shown by 2020, not including retirements, is 5115 MW, which is still 

substantial. With retirements, the shortage shown in 2015 is 5993 MW, and in 2020 is 

17,551 MW (Table 8-3). 

In the ERCOT region, STPNOC estimated about 24.5 percent of current generating capacity is 

currently considered to be baseload and that this percentage would rise to 30.1 percent by 2012 

(STPNOC 2010). In its ER, STPNOC estimated the combined capacity of baseload generation 

that addresses ERCOT through 2012 based on the ERCOT criteria (Table 8-4). The 

percentage of baseload may be increasing (STPNOC 2010). STPNOC noted that STP Units 1 

and 2 and Comanche Peak Units 1 and 2 would represent 4892 MW of the 22,178 MW of total 

summer baseload generating capacity needed in the ERCOT region in 2012 (STPNOC 2010). 

The growth in need for baseload generation in Table 8-4 from 2007 to 2012 is 4557 MW, of 

which only 2100 MW of new coal and gas had been added to the ERCOT forecast. In the 

longer term, plant retirements and further increases in demand for power allowed STPNOC 

(STPNOC 2010) to conclude that: 

Thus, the need for new capacity in ERCOT in 2015-2016 is substantially greater than the 

new capacity to be provided by STP 3 & 4. As a result, not only will there be a need for 

power from STP 3 & 4, there will be a need for a substantial amount of other new 

generating capacity. 

Table 8-4. STPNOC Forecasted Summer Capacity, Baseload Generation Units Only 

 2007 2008 2009 2010 2011 2012 

Resources, MW 71,812 72,048 71,960 72,394 72,939 73,703 

Baseload Generation, MW 17,621 17,621 19,057 19,998 21,378 22,178 

Percent of Resources that 

are Baseload Generation 

24.50% 24.50% 26.50% 27.60% 29.30% 30.10% 

Source: STPNOC 2010 

Review Team Sensitivity Tests of the 2010 ERCOT Forecast 

The review team examined the STPNOC analysis and the newer ERCOT forecasts and decided 

to test the STPNOC analysis both in light of the revised ERCOT forecast and events that have 

occurred in Texas since the ERCOT forecast was made that might affect STPNOC’s 

conclusions. Table 8-5 shows the net effects of a sensitivity test of the ERCOT 2010 firm load 

and resource forecasts made by the review team to test the need for baseload power in 2010 

through 2025. There were several elements added to the extended ERCOT estimate made in 

Table 8-3. The sensitivity test elements in Table 8-5 are bold and italicized. 

• The 2010 ERCOT firm load forecast was reduced following discussions with ERCOT 

forecasters concerning the potential impacts of a number of recent events on the 2010 
Need For Power 

NUREG-1937 8-26 February 2011 

forecast (Scott 2010). To account for the entire unaccounted-for portion of new energy 

efficiency programs, the current 242 MW adjustment for HB 3693 programs was increased 

by 5 percent of the change in the cumulative growth from 2010 to 2012 in the ERCOT 

forecast for 2012 and by 10 percent in and after 2013. This additional adjustment accounts 

for new PUCT and municipal utility goals not captured by the ERCOT econometric forecast. 

Enhanced funding of energy conservation and regulatory actions, such as the new 

residential building codes adopted by the State and several municipalities within the State, 

may not be fully captured by the 2010 ERCOT forecast. However, new energy codes have 

been adopted continuously by Texas municipalities during the 2000-2010 period ahead of 

statewide actions in 2010 and much of their impact would have been included in the ERCOT 

forecast. For example, most of the large utilities had adopted the 2006 or even the 2009 

version of the International Energy Conservation Code before the State did (Energy 

Systems Laboratory 2010). The corresponding electricity savings would have been 

reflected in the trend in electricity consumption during the period that formed the basis for 

ERCOT’s forecast. There is almost no currently available, reliable information that suggests 

the impacts of the latest statewide code adoption, ARRA-funded projects, or other very 

recent programs have been significant on a statewide basis or that they require a significant 

adjustment to the ERCOT forecasts. 

• An additional 8927 MW (with an ELCC of 777 MW) was added to ERCOT’s forecasted 

installed wind generation after 2015 to account for the build-out of installed wind capacity to 

the CREZ Study’s Scenario 2 planning figure of 18,456 MW (with an ELCC of 1606 MW). 

The ELCC values appear in Table 8-5. Some of this generation capability may in fact be 

non-wind renewable generation. This assumption accounts for a mid-range estimate of 

additional renewable energy not captured in the 2010 ERCOT forecast. 

• The generating capacity of the oldest fossil-fuel-fired generating plants was subtracted from 

the generating capacity. In 2015, 6123 MW was subtracted to account for plants that may 

be de-rated or retired due to age (at least 50 years old), cost, or environmental regulations 

as calculated by NERC. After 2015, there were additional plants at least 50 years old that 

might be retired for environmental or economic reasons. Although the impacts of 

retirements on reserve margins are also shown in Table 8-3, they are not part of the ERCOT 

reference forecast. 

• Needed baseload plants are not discussed in the ERCOT forecast. Needed baseload plants 

were calculated at 39 percent of peak generation requirements. In the discussion of Figure 

8-3, baseload was 44 percent of peak demand. This was calculated by taking the 2009 

actual load in the 80th percentile hour of the load duration curve (28,215 MW) and dividing it 

by peak demand in the 2009 peak load (actual, so considered firm load), plus 13.75 percent 

reserve margin. Because plenty of reserve units are available at minimum demand, the 

review team did not consider it necessary to adjust the forecast demand for baseload 

generation by a reserve margin, resulting in an incremental demand for baseload equal to 

39 percent of peak. 
Need For Power 

February 2011 8-27 NUREG-1937 

The assessment in Table 8-5 was done with and without the retirement of older power plants. 

For purposes of this estimate it was assumed that baseload power would represent about 

39 percent of the identified peak generating needs. This percentage is larger than the 

30.1 percent calculated by STPNOC for 2012, but is in line with industry practice as described in 

Section 8.2. The table shows that with or without retirements, the ERCOT 13.75 percent target 

reserve margin is not met in 2020 and requires new baseload generation. With retirements, 

new baseload generation is needed in 2015. Even with lowered ERCOT forecasts for future 

electricity demand due to recession, granted success for nascent Texas energy efficiency 

programs, and a full build-out of the State’s planned wind program, the combination of load 

growth and plant retirements still show a need for power. 

Table 8-6 shows the impact of the sensitivity calculations (Table 8-5) on the need for additional 

generation capacity. Without any retirements, Table 8-6 shows that there is no demand for new 

baseload in 2015, but the demand for baseload grows to 1261 MW in 2020, a reflection of much 

higher planned non-wind resources and wind power penetration into the Texas market than 

assumed in 2007, combined with lower load growth than assumed by STPNOC’s forecast. But 

with only plants greater than 50 years old retiring, the demand for new baseload plants not 

currently in the forecast grows to 2100 MW in 2015 and to 6400 MW in 2020, which is enough 

for two new nuclear units. Even with lowered ERCOT forecasts for future electricity demand 

due to recession, granted success for nascent Texas energy efficiency programs, and a full 

build-out of the State’s planned wind program, the combination of load growth and plant 

retirements still shows a need for power. 

8.4 Assessment of Need for Power 

The review team reviewed reports prepared by ERCOT regional ISO in conjunction with its 

assessment of the need for power from STPNOC’s proposed Units 3 and 4 at the STP site. 

STPNOC (STPNOC 2010) relied on the 2007 versions of these reports, which show a slightly 

higher need for power than the 2008, 2009, and 2010 reports; however, all versions provide 

essentially the same picture. The review team’s key findings from the reports and their impact 

on the need for baseload power are summarized as follows: 

• The demand for power at the summer peak and the annual demand for energy in the 

ERCOT region are both projected to rise over the period 2010 through 2020 at 

approximately 1.7 percent per year compounded (ERCOT 2010a). Total firm load would 

be 73,863 MW at peak in 2020, and including a 13.75 percent reserve requirement, 

resources would need to be about 84,019 MW in that year. Due to their low marginal 

operating cost, nuclear reactors occupy the minimum-demand portion of the load 

duration curve – they always run if available. If ERCOT’s minimum-hour demand and 

80th percentile hourly demand also increase at the 1.7 percent rate, by 2018 the ERCOT 
Need For Power 

NUREG-1937 8-28 February 2011 Table 8-5. Review Team Sensitivity Test, ERCOT Region Forecasted Summer Resources, 2010-2025 2010 2011 2012 2013 2014 2015 2020 2025 Firm Load (Table 8-1), Less Additional Efficiency 62,412 63,532 64,874 66,208 67,231 68,141 72,807 76,494 Installed Capacity, MW 66,228 63,896 63,896 63,896 63,896 63,896 63,896 63,896 Capacity from Private Networks, MW 4803 4803 4803 4803 4803 4803 4803 4803 ELCC of Existing Wind Generation, MW 793 829 829 829 829 829 829 829 RMR Units to be under Contract, MW 688

0 0 

0

0

0

0

0

Operational Generation, MW 72,512 69,528 69,528 69,528 69,528 69,528 69,528 69,52850% of Non-Synchronous Ties, MW 553 553 553 553 553 553 553 553Switchable Units, MW 2848 2,962 2,962 2,962 2,962 2962 2962 2962Available Mothballed Generation, MW 

0 191 223 239 255 271 271 271

Planned Units (not wind) with SIA and Air Permit, MW 

0 740 1,895 1,895 4,055 4835 5495 5495

ELCC of Planned Wind Units with SIA, MW 

0

0 35 76 96 96 777 777

Total Resources, MW 75,913 73,974 75,196 75,253 77,449 78,245 79,586 79,586Less Switchable Units Unavailable to ERCOT, MW 

158 317 0 

0

0

0

0

0

Less Retiring Units in Forecast 

0

0 0 

0

0

0

0

Retirements: NERC 2010 or age >50 yrs 

0

0 0 

0

0 6,123 12,437 20,385

Resources, MW (no retirements) 75,755 73,657 75,196 75,253 77,449 78,245 79,586 78,586Reserve Margin Above Firm Load (no retirements 21.4% 15.9% 15.9% 13.7% 15.2% 14.8% 9.3% 4.0%Resources, MW (with retirements) 75,755 73,657 75,196 75,253 77,449 72,122 67,149 59,201Reserve Margin Above Firm Load (with retirements) 

21.4% 15.9% 15.9% 13.7% 15.2% 5.8% -7.8% -22.6%

Sources: 1) ERCOT 2010b, e, f; 2) review team calculations based on the expanded wind resource availability of 18,456 installedMW by 2018; and 3) retirements based on NERC 2010 and the >50-year-old generation retirement scenarios in Figure 8-10. 
Need For Power 

February 2011 8-29 NUREG-1937 

Table 8-6. ERCOT/Review Team Forecasted Summer Capacity, Baseload Generation Units 

Only(a)

2009 2010 2015 2020 2025 

Power Requirements, Including Reserve 

Margin (MW) 

69,569 70,214 77,510 82,818 87,012 

Projected New Generation: No Retirements (MW) 

Generating Resources 72,712 75,755 78,245 79,586 79,586 

 Resource Additions Needed after 2009 -- (5541) (734) 3233 7426 

Baseload Needed 

(39% of Power Requirements) 

24,349 27,383 30,229 32,299 33,935 

Baseload Additions Needed After 2009 -- (2161) (286) 1261 2896 

Projected New Generation: Retire Only Plants >50 Yr Old (MW) 

Generating Resources 73,029 75,755 72,122 67,149 59,201 

Resource Additions Needed after 2009 -- (5541) 5389 15,669 27,811 

Baseload Needed 

(39% of Power Requirements) 

24,349 27,383 30,229 32,299 33,935 

Baseload Additions Needed After 2009 -- (2161) 2102 6111 10,846 

(a) Excludes proposed STP Units 3 and 4. 

region would need an additional 3600 to 4700 MW of nuclear-like baseload generation due 

to load growth alone This estimate, however, does not account for other supply plans and 

other changes in the market since the 2010 ERCOT forecast was released. 

• As noted in Section 8.3, retiring generating units were not counted in the 2010 forecast of 

ERCOT region available resources (retirements are shown as zero in forecasted resources). 

Thus, depending on the rate of retirement of older generating units, the ERCOT region may 

need substantial additional generating capacity by 2020. ERCOT tracks plants that are at 

least 30, 40 and 50 years old as potential candidates for retirement. The analysis in 

Table 8-3 shows that if only the oldest units (at least 50 years old) are retired after 2010, by 

2020 the amount of additional demand for new generation would be about 12,437 MW 

relative to a case with no retirements. About 39 percent of that growth (4850 MW) likely 

would be baseload generation and would by itself be enough demand to warrant a 2700 MW 

nuclear plant. 

• The 2010 ERCOT resource forecast (ERCOT 2010b), updated in December 2010 (ERCOT 

2010e), contains 9529 MW of current installed wind capacity in 2010 (with 829 MW of 

average ELCC) plus 1103 MW of planned installed capacity (average ELCC of 96 MW) by 

2015. However, ERCOT (2008e) also acknowledges that larger amounts of additional wind 
Need For Power 

NUREG-1937 8-30 February 2011 

generation capacity (ranging up to 24,400 MW installed [average ELCC of 2122 MW]) may 

be built in the CREZ areas of Texas. Large amounts of wind generation would require major 

investments in transmission resources and improved system controls to manage wind 

resources, but could reduce the demand for non-wind power during the off-peak portions of 

the year and may, at times, limit the demand for additional intermediate and baseload 

thermal generating resources. More modest market penetration of wind energy leaves a 

market for increased baseload generation. The discussion of the CREZ study in Section 8.3 

favors a lower wind penetration rate with up to 18,456 MW cumulative installed capacity, 

given very aggressive wind development (ERCOT 2008h). Table 8-5 shows that a build-out 

of this wind generation would reduce future need for other generating resources an 

additional 777 MW (the ELCC of the additional 8927 MW installed after 2010, of which 1103 

MW with an ELCC of 96 MW is already in the forecast). However, Table 8-2 is a lessdetailed extension of Table 8-1 to the year 2025 that shows the ERCOT 2010 forecast of 

demand and reserve margin (ERCOT calculated long-term required resources to meet peak 

demand plus 13.75 percent after 2010). There are a number of additional aggressive 

energy efficiency programs being considered in Texas during 2010 that are not considered 

in the ERCOT forecast methodology or in the need for power analysis because they are not 

Texas law, regulation, or policy. There are a number of other emerging programs, however, 

for which there is not enough performance information available to determine their 

quantitative effect on even the most recent ERCOT forecast. 

• Table 8-2 shows that even a conservative increase in the demand for baseload generating 

resources driven by retirements is much larger than the reduction due to wind build-out, 

leaving a net increase in demand of 2102 MW in 2015 and 6111 MW in 2020. Because 

there is uncertainty in the success of aggressive wind generation and because nuclear 

plants can substitute for other potential baseload generation, the review team believes that 

aggressive wind generation development still leaves a need for the amount of electrical 

generation represented by STP Units 3 and 4. 

• In part because of the successes of past energy efficiency programs and greater availability 

of federal funding, the State of Texas has embarked on much more aggressive programs to 

save electricity, including PUCT goals of up to 30 percent reduction in load growth for 

regulated utilities, comparably ambitious programs at several municipal utilities, and several 

forms of assistance from the State’s energy and housing offices (SECO and TDHCA) to 

make the State’s stock of buildings and appliances more efficient. Currently, little is known 

yet concerning the actual results of these programs after 2009, because some were 

temporary and already had their effect in the base year actual energy consumption and 

many of the others are less than a year old. In the sensitivity analysis in Section 8.3, the 

review team gave the programs credit for reducing electricity demand 531 MW by 2015 and 

1056 MW by 2020 beyond that already included in the ERCOT 2010 forecast. However, if 

the programs were as successful as projected in the sensitivity case, the total demand for 

generating resources, less the actual resources in 2009, would still grow 3200 MW without 
Need For Power 

February 2011 8-31 NUREG-1937 

retirements or 15,700 MW with retirements by 2020. If 39 percent were for baseload 

generation, the net demand for new baseload would be about 1300 to 6100 MW. 

• When both increased demand and planned supply factors are considered, the extended 

2010 ERCOT forecast in Table 8-3 shows a net need for new total generation of 0 MW in 

2015 and 5115 MW in 2020, not accounting for potential retirements, which implies a need 

for new baseload generation of 0 MW to 1995 MW at 39 percent of the total. With 

retirements the implied need for new baseload generation is 2337 MW in 2015 and 6845 

MW in 2020. Table 8-5, which takes all of the various review team sensitivity tests into 

account, shows a net need for new total generation in the 2015 to 2020 period ranging from 

0 MW in 2015 to 3233 MW in 2020 without retirements and from 5389 MW in 2015 to 

15,669 MW in 2020 with a conservative estimate of potential retirements. The 

corresponding ranges for baseload generation are 0 MW in 2015 to 1261 MW in 2020 and 

2102 MW in 2015 to 6111 MW in 2020. 

The net effect of various sensitivity tests shows a net need for power in the period from 2015 

through 2020. 

Table 8-7 summarizes the results of the review team analysis of the ERCOT electricity demand 

and supply forecasts that have occurred since STPNOC used the ERCOT 2007 forecasts to 

estimate unmet need for power from STP Units 3 and 4. The review team reviewed the ERCOT 

2008, 2009, and 2010 demand forecasts, noted the changes since 2007, and decided that while 

ERCOT’s short-term forecast of peak summer demand was heavily influenced by the 2008 to 

2009 recession, the longer-term estimate of demand also was affected. Another important 

issue is that the supply forecasts did not include the full impact of recent ambitious demand 

reduction programs, the full scope of wind power in Texas, or the effects of capacity retirements 

on the need for power. The review team conducted some sensitivity tests that added these 

elements to the 2010 ERCOT long-term supply forecast. Based on information available in 

STPNOC’s need for power analysis, the review team translated the modified ERCOT 2010 

demand and supply forecasts into an estimate of the unmet need for baseload power in ERCOT 

from 2015 through 2020, which spans the potential completion dates for proposed STP 

Units 3 and 4. 
Need For Power 

NUREG-1937 8-32 February 2011 

Table 8-7. ERCOT/Review Team Forecasted Unmet Need for Baseload Generation 

Compared with STPNOC Estimated Need for Baseload Power 

Review Team/ 

ERCOT 2010 

(2015 and 2020) MW

STPNOC/ 

ERCOT 2007 

(2017) MW 

Estimated Baseload Demand 30,300 to 32,300(a) 26,600(b)

Estimated Baseload Supply 30,500 to 26,200(c) 9900 to 20,100(d)

Unmet Net Need for Baseload Power 0 to 6100(e) 6500 to 16,700(f)

Proposed Capacity 2740 2740 

(a) Table 8-5, 2015 and 2020 power requirements times 39%. 

(b) STPNOC 2010, Figure 8.4-2, 2017 “Total Requirement” times 30.1%. 

(c) Table 8-5, 2015 and 2020 resources with and without retirements, times 39%. 

(d) STPNOC 2010, Figure 8.4-2, 2017 “Capacity less units 50 years old or older,” 

“Capacity less units 30 years old or older,” times 30.1%. 

(e) Range of differences between demand and supply. 

(f) Range of differences between demand and supply. 

Table 8-7 shows that the demand for baseload power in 2017 has changed since the 2007 

analysis, and the combination of potential conservation and wind power may have significantly 

reduced the need for baseload power. However, even though the potential unmet need for 

power in the review team’s alternative estimate is much smaller than STPNOC’s estimate, it still 

shows an unmet need large enough to accommodate proposed STP Units 3 and 4 sometime 

between 2015 and 2020. In addition, because STP Units 3 and 4 would be merchant plants, 

STPNOC does not need to show an absolute shortage of power. The marketplace would 

decide whether Units 3 and 4 would be able to compete successfully with other potential 

suppliers of baseload electricity. 

8.4.1 Conclusion 

The review team concludes that there is an expected future shortage of baseload power in the 

ERCOT region that could be at least partially addressed by construction of proposed Units 3 

and 4 at the STP site. Although a recent recession has reduced the ERCOT forecast of future 

demand for electricity on which STPNOC relied and public policy could further limit demand and 

add to potential supply, the review team determined that the STPNOC assessment of its need 

for power in its ER is not unreasonable. Building of the two new units could address (1) growth 

in demand for baseload power and (2) replacement of retiring baseload generating units 

elsewhere in the ERCOT region. Based on its analysis, the review team concludes that there is 

a justified need for the planned 2740 MW baseload capacity output of proposed STP Units 3 

and 4 in the ERCOT region. 
Need For Power 

February 2011 8-33 NUREG-1937 

8.5 References 

26 U.S.C. 501. 2010. Title 26, Internal Revenue Code, Subtitle A, Chapter 1, Subchapter F, 

Part I, §501 “Exemptions from Tax on Corporations, Certain Trusts, etc.” United States Code. 

Internal Revenue Service. 

68 FR 55910. September 29, 2003. “Nuclear Energy Institute; Denial of Petition for 

Rulemaking.” Federal Register. U.S. Nuclear Regulatory Commission. 

American Recovery and Reinvestment Act of 2009. Public Law No: 111-5. 

Austin Energy. 2010. “Austin Council Approves Green Energy Plan.” Austin Energy Press 

Release, April 22, 2010. Accessed on November 30, 2010 at 

http://www.austinenergy.com/About%20Us/Newsroom/Press%20Releases/2010/greenEnergyA

pproval.htm 

Cordaro, M. 2008. Understanding Base Load Power. What it is and Why it Matters. Published 

by Dr. Matthew Cordaro in conjunction with New York Affordable Reliable Electricity Alliance 

(New York AREA). Accessed January 7, 2011 at http://www.areaalliance.org/documents/base%20load%20power.pdf. 

CPS Energy. 2010. “CPS Energy Resolves to Save 58 Megawatts in 2011.” CPS Energy 

Press Release. Accessed on January 21, 2011 at 

http://www.cpsenergy.com/About_CPS_Energy/News_Features/News/123010_EE_Successes_

NR.asp. 

Electric Reliability Council of Texas (ERCOT). 2005a. “Methodology for Reserve Margin 

Calculation,” Memorandum from Read Comstock, TAC chair to ERCOT Board of Directors, May 

10, 2005. 

Electric Reliability Council of Texas (ERCOT). 2005b. Reserve Margin Update - House 

Committee on Regulated Industries; PowerPoint Presentation. Electric Reliability Council of 

Texas. 

Electric Reliability Council of Texas (ERCOT). 2007. 2007 ERCOT Planning Long-Term Hourly 

Peak Demand and Energy Forecast, May 8, 2007. Austin, Texas. Accessed at 

http://www.ercot.com/news/presentations/2007/2007_ERCOT_Planning_Long_Term_Hourly_D

emand_Energy_Forecast_.pdf. 

Electric Reliability Council of Texas (ERCOT). 2008a. ERCOT Company Profile. Austin, 

Texas. Accessed May 13, 2009 at http://www.ercot.com/about/profile/index.html. 
Need For Power 

NUREG-1937 8-34 February 2011 

Electric Reliability Council of Texas (ERCOT). 2008b. ERCOT Governance. Austin, Texas. 

Accessed May 13, 2009 at http://www.ercot.com/about/governance/index.html. 

Electric Reliability Council of Texas (ERCOT). 2008c. About ERCOT. Austin, Texas. 

Accessed May 13, 2009 at http://www.ercot.com/about/index. 

Electric Reliability Council of Texas (ERCOT). 2008d. 2008 ERCOT Planning Long-Term 

Hourly Peak Demand and Energy Forecast. Austin, Texas. Accessed June 24, 2009 at 

http://www.ercot.com/content/news/presentations/2008/2008%20Planning%20LongTerm%20Hourly%20Demand%20Energy%20Forecast%20Final.doc. 

Electric Reliability Council of Texas (ERCOT). 2008e. ERCOT Long-Term System Assessment 

December 2008. Austin, Texas. Accessed June 24, 2009 at 

http://www.ercot.com/content/news/presentations/2008/ERCOT_LongTerm_System_Assmt_Dec_2008.pdf. 

Electric Reliability Council of Texas (ERCOT). 2008f. Texas Regional Entity. Austin, Texas. 

Accessed May 14, 2009 at http://www.ercot.com/mktrules/compliance/tre/index. 

Electric Reliability Council of Texas (ERCOT). 2008g. ERCOT Capacity, Demand, Reserves 

Winter Update. Austin, Texas. Accessed June 24, 2009 at 

http://www.ercot.com/content/news/presentations/2009/ERCOT_CDR_update_12-15-

08_public.xls. 

Electric Reliability Council of Texas (ERCOT). 2008h Competitive Renewable Energy Zones 

(CREZ) Transmission Optimization Study, ERCOT System Planning, April 2, 2008. Austin, 

Texas. Available at http://www.ercot.com/news/presentations/2008/index. 

Electric Reliability Council of Texas (ERCOT). 2008i. ERCOT Membership. Austin, Texas. 

Accessed May 14, 2009 at http://www.ercot.com/about/governance/members/. 

Electric Reliability Council of Texas (ERCOT). 2009a. 2009 ERCOT Planning Long-Term 

Hourly Peak Demand and Energy Forecast. Austin, Texas. Available at 

http://www.ercot.com/content/news/presentations/2009/2009_Planning_LongTerm_Hourly_Demand_Energy_Forecast-av2009.pdf. 

Electric Reliability Council of Texas (ERCOT). 2009b. Report on the Capacity, Demand, and 

Reserves in the ERCOT Region, System Planning. Austin, Texas. Available at 

http://www.ercot.com/content/news/presentations/2009/2009%20ERCOT%20Capacity,%20De

mand%20and%20Reserves%20Report.pdf. 
Need For Power 

February 2011 8-35 NUREG-1937 

Electric Reliability Council of Texas (ERCOT). 2009c. Hourly Load Data Archives. Austin, 

Texas. Available at http://www.ercot.com/gridinfo/load/load_hist/. 

Electric Reliability Council of Texas (ERCOT). 2010a. 2010 ERCOT Planning Long-Term 

Hourly Peak Demand and Energy Forecast. Austin, Texas. Available at 

http://www.ercot.com/content/news/presentations/2010/2010_Planning_LongTerm_Hourly_Demand_Energy_Forecast-av2009.pdf. 

Electric Reliability Council of Texas (ERCOT). 2010b. Report on the Capacity, Demand, and 

Reserves in the ERCOT Region, System Planning. May 2010. Austin, Texas. Available at 

http://www.ercot.com/content/news/presentations/2009/2009%20ERCOT%20Capacity,%20De

mand%20and%20Reserves%20Report.pdf. 

Electric Reliability Council of Texas (ERCOT). 2010c. ERCOT Using New Forecasting Tool to 

Prepare for Wind Variability. ERCOT press release. March 25, 21010. Available at 

http://www.ercot.com/news/press_releases/2010/nr-03-25-10a. 

Electric Reliability Council of Texas (ERCOT). 2010d. Draft Minutes of the Board of Directors 

Meeting of Electric Reliability Council of Texas, Inc. November 16, 2010. Available at 

http://www.ercot.com/committees/board.

Electric Reliability Council of Texas (ERCOT). 2010e. Report on the Capacity, Demand, and 

Reserves in the ERCOT Region, System Planning, December 2010, Revision 1. Austin, Texas. 

Available at 

http://www.ercot.com/content/news/presentations/2011/ERCOT%202010%20Capacity,%20De

mand%20and%20Reserves%20Report%20-%20Winter%20Upd.pdf. 

Electric Reliability Council of Texas (ERCOT). 2010f. ERCOT Long-Term System Assessment 

December 2010. Austin, Texas. Available at http://www.ercot.com/news/presentations/ 

Energy Policy Act of 2005, as amended. 42 USC 15801, et seq.

Federal Energy Regulatory Commission (FERC). 1999. 89 FERC 61,285. U.S. Federal 

Energy Regulatory Commission 18 CFR Part 35 [Docket No. RM99-2-000; Order No. 2000], 

Regional Transmission Organizations (Issued December 20, 1999). 

Federal Energy Regulatory Commission (FERC). 2008. Regional Transmission Organizations 

(RTO)/Independent System Operators (ISO). Accessed May 14, 2009 at 

http://www.ferc.gov/industries/electric/indus-act/rto.asp. Accession No. ML100600754. 

Global Energy Decisions (GED). 2007. ERCOT Target Reserve Margin Analysis. Prepared for 

ERCOT. Date submitted January 18, 2007. Sacramento, California. 
Need For Power 

NUREG-1937 8-36 February 2011 

Governor’s Competitiveness Council. 2008. 2008 Texas State Energy Plan. Governor’s 

Competitiveness Council, Austin, Texas. 

National Environmental Policy Act of 1969, as amended (NEPA). 42 USC 4321, et seq. 

North American Electric Reliability Corporation (NERC). 2008a. North American Electric 

Reliability Corporation. Accessed May 14, 2009 at http://www.nerc.com/. Accession No. 

ML100600754. 

North American Electric Reliability Corporation (NERC). 2008b. 2008 Long-Term Reliability 

Assessment 2008-2017. Available at http://www.nerc.com/files/FinalFiled2008LTRA.pdf. 

Accession No. ML100600754. 

North American Electric Reliability Corporation (NERC). 2010. 2010 Special Reliability 

Scenario Assessment: Resource Adequacy Impacts of Potential U.S. Environmental 

Regulations. NERC, Princeton, NJ, October 2010. 

Progress Arkansas. 2010. “Base Load Power: What Arkansans Need to Know.” Available at 

http://www.progressarkansas.com/documents/base%20load%20power.pdf. 

Public Service Commission of Wisconsin (PSC-Wisconsin). 2009. “Electric Power Plants.” 

Accessed on January 11, 2001 at http://psc.wi.gov/thelibrary/publications/electric/electric04.pdf. 

Scott, Michael. 2010. Summary of teleconference with ERCOT on December 18, 2010. 

ML103500553. 

South Texas Project Nuclear Operating Company (STPNOC). 2010. South Texas Project Units 

3 and 4 Combined License Application, Part 3, Environmental Report. Revision 4, Bay City, 

Texas. Accession No. ML102860592. 

Texas A&M University Energy Systems Laboratory (Energy Systems Laboratory). 2010. 2010 

Texas Jurisdiction Energy Code Adoption Survey. ESL-TR-10-06-01. Accessed on February 

4, 2011 at http://www-esl.tamu.edu/terp/reports/2010. 

Texas Department of Housing and Community Affairs (TDHCA). 2010. Weatherization 

Assistance Program (WAP). Accessed July 6, 2010 at http://168.39.88.72/recovery/detailwap.htm. 

Texas Legislature Online. 2010. 81(R) Text for HB 1937. Accessed December 14, 2010 at 

http://www.legis.state.tx.us/billlookup/Text.aspx?LegSess=81R&Bill=HB1937. 
Need For Power 

February 2011 8-37 NUREG-1937 

Texas Register. 2010a. Adopted Rule, 16 Texas Administrative Code §25.181, 35 Tex. Reg. 

7747 (August 27, 2010). Available at 

http://www.sos.state.tx.us/texreg/pdf/backview/0827/0827adop.pdf. 

Texas Register. 2010b. Adopted Rules. 35 Tex. Reg. 4729. June 4, 2010. Title 34, Part 1, 

Chapter 19, Subchapter E, 34 TAC §19.53. 

Texas State Energy Conservation Office (SECO). 2010. SECO Stimulus - American Recovery 

and Reinvestment Act of 2009 (ARRA). Accessed on December 13, 2010 at 

http://www.seco.cpa.state.tx.us/arra/. 

Texas Utility Code, Title 2, Public Utility Regulatory Act. Chapter 39, “Restructuring of Electric 

Utilities Industry.” 

U.S. Department of Energy-Energy Information Administration (DOE/EIA). 2009. Annual 

Energy Outlook 2010, Early Release, Dec 14, 2009. DOE.EIS-03838(2010). Accessed 

January 14, 2009 at http://www.eia.doe.gov/oiaf/aeo/index.html. Accession No. ML100600754. 

U.S. Department of Energy-Energy Information Administration (DOE/EIA). 2011. “Energy 

Glossary.” Accessed on January 11, 2011 at http://www.eia.doe.gov/glossary/index.cfm?id=B. 

Accession No. ML110190235. 

U.S. Nuclear Regulatory Commission (NRC). 2000. Environmental Standard Review Plan— 

Standard Review Plans for Environmental Reviews for Nuclear Power Plants. NUREG-1555, 

NRC, Washington, D.C. Includes 2007 updates. 

U.S. Nuclear Regulatory Commission (NRC). 2010. Staff Memorandum from Scott Flanders, 

DSER Division Director, to Brent Clayton, RENV Branch Chief, dated December 10, 2010, 

regarding Addressing Construction and Preconstruction Activities, Greenhouse Gas Issues, 

General Conformity Determinations, Environmental Justice, Need for Power, Cumulative Impact 

Analysis, and Cultural/Historical Resources Analysis Issues In Environmental Impact 

Statements. Accession No. ML100760503.

February 2011 9-1 NUREG-1937 

9.0 Environmental Impacts of Alternatives 

This chapter describes alternatives to the proposed U.S. Nuclear Regulatory Commission 

(NRC) action for a combined license (COL) and the U.S. Army Corps of Engineers (Corps) 

action for an Individual Permit and discusses the environmental impacts of those alternatives. 

Section 9.1 discusses the no-action alternative. Section 9.2 addresses alternative energy 

sources. Section 9.3 reviews the STP Nuclear Operating Company’s (STPNOC’s) region of 

interest (ROI), its site selection process, and summarizes and compares the environmental 

impacts for the proposed and alternative sites. Section 9.4 examines plant design alternatives. 

Section 9.5 describes onsite alternatives. Section 9.6 lists the references cited in this chapter. 

The need to compare the proposed action with alternatives arises from the requirement in 

Section 102(2)(c)(iii) of the National Environmental Policy Act of 1969, as amended (NEPA) 

(42 USC 4321) that environmental impact statements (EISs) include an analysis of alternatives 

to the proposed action. The NRC implements this comparison through its regulations in Title 10 

of the Code of Federal Regulations (CFR) Part 51 and its Environmental Standard Review Plan 

(ESRP) (NRC 2000). The environmental impacts of the alternatives are evaluated using the 

NRC’s three-level standard of significance – SMALL, MODERATE, or LARGE – developed 

using Council on Environmental Quality (CEQ) guidelines (40 CFR 1508.27) and set forth in the 

footnotes to Table B-1 of 10 CFR 51, Subpart A, Appendix B. The issues evaluated in this 

chapter are the same as those addressed in the Generic Environmental Impact Statement for 

License Renewal of Nuclear Plants (GEIS), NUREG-1437, Volumes 1 and 2 (NRC 1996, 

1999)(a) with the additional issue of environmental justice. Although NUREG-1437 was 

developed for NRC’s review of renewal of nuclear power plant operating licenses, it provides 

useful information for this review and is referenced throughout this chapter. Additional guidance 

on conducting environmental reviews is provided in NRC Staff Memorandum Addressing 

Construction and Preconstruction, Greenhouse Gas Issues, General Conformity 

Determinations, Environmental Justice, Need for Power, Cumulative Impact Analysis, and 

Cultural/Historical Resources Analysis Issues in Environmental Impact Statements (NRC 2010). 

As part of the evaluation of permit applications subject to Section 404 of the Federal Water 

Pollution Control Act (Clean Water Act), the Corps is required by regulation to apply the criteria 

set forth in the 404(b)(1) guidelines (33 USC 1344; 40 CFR Part 230). These guidelines 

establish criteria that must be met for the proposed activities to be permitted pursuant to 

Section 404. 

Section 230.10(a) of the Guidelines (40 CFR 230.10(a)) requires that “no discharge of dredged 

or fill material shall be permitted if there is a practicable alternative to the proposed discharge 

 

(a) NUREG-1437 was originally issued in 1996. Addendum 1 to NUREG-1437 was issued in 1999 

(NRC 1999). Hereafter, all references to NUREG-1437 include NUREG-1437 and its Addendum 1. 
Environmental Impacts of Alternatives 

NUREG-1937 9-2 February 2011 

which would have less adverse impact on the aquatic ecosystem, so long as the alternative 

does not have other significant adverse environmental consequences.” Section 230.10(a)(2) of 

the Guidelines states that “An alternative is practicable if it is available and capable of being 

done after taking into consideration cost, existing technology, and logistics in light of overall 

project purposes. If it is otherwise a practicable alternative, an area not presently owned by the 

applicant which could reasonably be obtained, used, expanded, or managed in order to fulfill the 

basic purpose of the proposed activity may be considered.” Thus, this analysis is necessary to 

determine which alternative is the Least Environmentally Damaging Practicable Alternative 

(LEDPA) that meets the project purpose and need. 

Where the activity associated with a discharge is proposed for a special aquatic site (as defined 

in 40 CFR Part 230, Subpart E), and does not require access or proximity to or siting within 

these types of areas to fulfill its basic project purpose (i.e., the project is not “water dependent”), 

practicable alternatives that avoid special aquatic sites are presumed to be available, unless 

clearly demonstrated otherwise (40 CFR 230.10(a)(3)). 

9.1 No-Action Alternative 

For purposes of an application for a COL, the no-action alternative refers to a scenario in which 

the NRC would deny the COLs requested by STPNOC which would result in the proposed units 

not being built. Likewise, the Corps could deny the Individual Permit request. Upon such a 

denial by the NRC, the construction and operation of two new nuclear units at the STP site in 

accordance with 10 CFR Part 52 would not occur and the predicted environmental impacts 

associated with the project would not occur. Preconstruction impacts associated with activities 

not within the definition of construction in 10 CFR 50.10(a) and 51.4 may occur nonetheless. If 

no other power plants were to be built in lieu of the proposed project or other strategy 

implemented to take its place, the benefits of the proposed project identified in Section 10.6.1 

including additional electrical capacity and electricity generation to be provided by the project 

would not occur. If no additional measures (e.g., conservation, importing power, restarting 

retired power plants, and/or extending the life of existing power plants) were implemented to 

realize the amount of electrical capacity that would otherwise be required for power in 

STPNOC’s ROI (see Section 9.3.1), then the need for baseload power, discussed in Chapter 8, 

would not be met. Therefore, the purpose and need of this project would not be satisfied if the 

no-action alternative was chosen and the need for power was not met by other means. 

If other generation sources were installed, either at another site or using a different energy 

source, the environmental impacts associated with these other sources would eventually occur. 

As discussed in Chapter 8, there is a demonstrated need for power. It is reasonable to assume 

that other options to meet the need for power would be pursued. This needed power may be 

provided and supported through a number of alternatives that are discussed in Sections 9.2 and 
Environmental Impacts of Alternatives 

February 2011 9-3 NUREG-1937 

9.3. Therefore, this section does not include a discussion of other energy alternatives that could 

meet the need for power. 

STPNOC’s permit request to the Corps covers the dredging of the barge slip along the Colorado 

River and the placement of culverts across six onsite drainages. If the dredging request were 

denied, potential alternatives would be constructing a large crane system to offload materials 

barged up the Colorado River, use of railroad lines to transport materials to the STP site instead 

of barge transport, and use of truck transport instead of barge transport. Alternatives to the 

placement of culverts would be to use current onsite roadways or span the existing drainages 

(STPNOC 2009b). In the event the Corps denies the permit request, STPNOC would need to 

decide if the proposed project could continue or if other alternatives should be pursued. 

9.2 Energy Alternatives 

The purpose and need for the proposed project identified in Section 1.3 is to provide additional 

baseload electrical generation capacity for use in the applicant’s current markets within the 

Electric Reliability Council of Texas (ERCOT) region and/or for potential sale on the wholesale 

market. This section examines the potential environmental impacts associated with alternatives 

to construction of a new baseload nuclear generating facility. Section 9.2.1 discusses energy 

alternatives not requiring new generating capacity. Section 9.2.2 discusses energy alternatives 

requiring new generating capacity. Other alternatives are discussed in Section 9.2.3. A 

combination of alternatives is discussed in Section 9.2.4. Section 9.2.5 compares the 

environmental impacts from new nuclear, coal-fired and natural gas-fired generating units, and a 

combination of energy sources at the STP site. 

For analysis of energy alternatives, STPNOC assumed a bounding target value of 2700 MW(e) 

electrical output (STPNOC 2010a). The review team also used this level of output in analyzing 

energy alternatives. 

9.2.1 Alternatives Not Requiring New Generating Capacity 

Four alternatives to the proposed action that do not require STPNOC to construct new 

generating capacity are to: 

• purchase the needed electric power from other suppliers 

• extend the operating life of existing power plants 

• reactivate retired power plants 

• implement conservation or demand-side management programs. 
Environmental Impacts of Alternatives 

NUREG-1937 9-4 February 2011 

Texas produces and consumes more electricity than any other state. Despite large net 

interstate electricity imports in some areas, the Texas interconnect power grid is largely isolated 

from the integrated power systems serving the eastern and western United States. In addition, 

most areas of Texas have little ability to export or import electricity to and from other states 

(DOE/EIA 2009a). If power to replace the capacity of the proposed new nuclear units was to be 

purchased from sources within the United States or from a foreign country, the generating 

technology likely would be one of those described in NUREG-1437 (e.g., coal, natural gas, or 

nuclear) (NRC 1996). The description of the environmental impacts of other technologies 

described in NUREG-1437, i.e., the GEIS for license renewal, is representative of the impacts 

associated with the construction and operation of new generating units at the STP site. The 

environmental impacts of coal-fired and natural gas-fired plants are discussed in Section 9.2.2. 

Under the purchased power alternative, the environmental impacts of power production would 

still occur but would be located elsewhere within the region, nation, or in another country. If the 

purchased power alternative were to be implemented, the most significant environmental 

unknown would be whether or not new transmission line corridors would be required. The 

acquisition and construction of new transmission corridors could have both environmental and 

aesthetic consequences. The review team concludes that the local environmental impacts from 

purchased power would be SMALL when existing transmission line corridors are used and could 

range from SMALL to LARGE if acquisition of new corridors is required. The overall 

environmental impacts of power generation would depend on the generation technology and 

location of the generation site and, therefore, are unknown. However, as discussed in Section 

9.2.5, the review team concluded that from an environmental perspective, none of the viable 

energy alternatives would be clearly preferable to construction of a new baseload nuclear power 

generation plant located within STPNOC’s ROI. 

Nuclear power facilities are initially licensed by the NRC for a period of 40 years. Operating 

licenses issued by the NRC can be renewed for up to 20 years; NRC regulations do not 

preclude multiple renewals. The operating license for STP Unit 1 expires in 2027, and the 

license for STP Unit 2 expires in 2028. STPNOC submitted an application to NRC on 

October 25, 2010 to renew the operating licenses of STP Units 1 and 2 (STPNOC 2010c). 

The environmental impacts of continued operation of a nuclear power plant are significantly less 

than construction of a new plant. However, continued operation of STP Units 1 and 2 already is 

considered in current energy planning. 

Older, existing fossil-fueled plants nearing the end of their useful lives, predominately coal-fired 

and natural gas-fired plants, are likely to need refurbishing to extend plant life for an extensive 

period (the proposed action assumes a minimum operating period of 40 years) and meet 

applicable environmental requirements. Given both the costs of refurbishment and the 

environmental impacts of operating such facilities, the review team concludes that extending the 
Environmental Impacts of Alternatives 

February 2011 9-5 NUREG-1937 

life of older, existing generating plants would not be a reasonable alternative to the proposed 

action. 

Retired generating plants, predominately coal-fired and natural gas-fired plants that potentially 

could be reactivated, would ordinarily require extensive refurbishment before reactivation. Such 

vintage plants typically would require refurbishment to meet current environmental requirements 

that would likely be costly. The environmental impacts of a reactivation scenario would be 

bounded by the impacts associated with coal-fired and natural gas-fired alternatives (see 

Section 9.2.2). Given both these costs and the environmental impacts of operating such 

facilities, the review team concludes that reactivating retired generating plants would not be a 

reasonable alternative to the proposed action. 

Improved energy efficiency and demand management strategies can potentially cost less than 

construction of new generation and provide a hedge against market, fuel, and environmental 

risks. NRG Energy, the controlling owner of Nuclear Innovation North America (NINA) and the 

primary seller of electricity in the ownership group, is a wholesale power generation company 

(Toshiba will not sell electricity from Units 3 and 4) (STPNOC 2010b). Consequently, it does not 

directly offer demand-side management or conservation programs. 

City Public Service Board of San Antonio (CPS Energy) is a retail electricity provider and offers 

a variety of energy conservation programs to its customers. It recently introduced a plan to 

support energy efficiency by treating it as a new fuel source for electrical generation. The plan 

projects how much the demand for electricity will grow over the next four years and seeks to 

reduce that amount by 10 percent each year in an effort to reach 40 percent by 2011. Through 

its Save for Tomorrow Energy Plan, CPS Energy’s goal is to achieve a cumulative reduction of 

approximately 771 MW(e) by 2020 (CPS 2009). To achieve this goal, CPS Energy is 

committing millions of dollars to customer incentives and rebates for the installation of high 

energy efficiency appliances, lighting, and insulation (CPS 2009). 

Among the energy conservation programs offered by CPS Energy to its customers are 

(STPNOC 2008a): 

Commercial Programs: 

• lighting retrofit programs 

• cool/thermal roof retrofits 

• high efficiency chiller and heating, ventilation, and air conditioning retrofits 

• efficient electric motors 

• window screening and tinting 

• incentives for solar water heaters and photovoltaic installations. 
Environmental Impacts of Alternatives 

NUREG-1937 9-6 February 2011 

Residential Programs: 

• rebates for high efficiency heating, ventilation, and air conditioning units 

• “peak save” programmable thermostats free to customers that allow cycling of air 

conditioning compressors in summer months to reduce peak electricity demand 

• home efficiency program that offers an array of rebates for attic insulation, duct work, wall 

insulation, solar powered attic fans, and window treatments 

• incentives for solar water heaters and photovoltaic installations. 

The need for power discussion in Chapter 8 takes account of conservation and demand-side 

management programs. The review team concluded in Chapter 8 that there is a justified need 

for power in the ERCOT region even with the implementation of conservation and demand-side 

management programs. 

Based on the preceding discussion, the review team concludes that the options of purchasing 

electric power from other suppliers, reactivating retired power plants, extending the operating 

life of existing power plants, and conservation and demand-side programs are not reasonable 

alternatives to providing new baseload power generation capacity. 

9.2.2 Alternatives Requiring New Generating Capacity 

Consistent with the NRC’s evaluation of alternatives to operating license renewal for nuclear 

power plants, a reasonable set of energy alternatives to building and operating one or more new 

nuclear units at the STP site should be limited to analysis of discrete power generation sources, 

a combination of sources, and those power generation technologies that are technically 

reasonable and commercially viable. The current mix of baseload power generation in ERCOT 

is one indicator of the feasible choices for power generation technology. In 2008, natural gasfired power plants accounted for about 43.0 percent of the electricity produced within ERCOT, 

coal-fired plants about 37.1 percent, nuclear plants about 13.2 percent, wind generation facilities 

about 4.9 percent, hydroelectric plants about 0.2 percent, and other sources about 1.6 percent 

(ERCOT 2009a). 

This section discusses the environmental impacts of energy alternatives to the proposed action 

that would require STPNOC to construct new generating capacity. The three primary energy 

sources for generating baseload electric power in the United States are coal, natural gas, and 

nuclear energy (DOE/EIA 2009b). Coal-fired plants are the primary source of baseload 

generation in the United States (DOE/EIA 2009b). Natural gas combined-cycle generation 

plants are often used as intermediate generation sources, but they are also used as baseload 

generation sources (SSI 2010). 
Environmental Impacts of Alternatives 

February 2011 9-7 NUREG-1937 

Each year, the Energy Information Administration (EIA), a component of the U.S. Department of 

Energy (DOE), issues an annual energy outlook. In its Updated Annual Energy Outlook 2009, 

EIA’s reference case projects that total electric generating capacity additions between 2007 and 

2030 will use the following fuels in the approximate percentages: natural gas (55 percent), 

renewables (27 percent), coal (14 percent), and nuclear (5 percent) (DOE/EIA 2009c). The EIA 

projection includes baseload, intermittent, and peaking units and is based on the assumption 

that providers of new generating capacity would seek to minimize cost while meeting applicable 

environmental requirements. 

The discussion in Section 9.2.2 is limited to a reasonable range of the individual energy 

alternatives that appear to be viable for new baseload generation: coal-fired and natural gas 

combined cycle generation. The impacts discussed in Section 9.2.2 are estimates based on 

present technology. Section 9.2.3 addresses alternative generation technologies that have 

demonstrated commercial acceptance but may be limited in application, total capacity, or 

technical feasibility when based on the need to supply reliable, baseload capacity. 

The review team assumed that (1) new generation capacity would be located at the STP site for 

the coal- and natural gas-fired alternatives, (2) the cooling approach planned for proposed 

Units 3 and 4 (Section 3.2.2.2) would be used for plant cooling, and (3) the existing transmission 

line corridors serving the STP site would be adequate to serve a new coal- or natural gas-fired 

plant sited there (Section 3.2.2.3). 

9.2.2.1 Coal-Fired Generation 

For the coal-fired generation alternative, the review team assumed construction of four 

supercritical pulverized coal-fired units, each with a net capacity of 675 MW(e). These 

assumptions are consistent with STPNOC’s COL application. Supercritical pulverized coal-fired 

plants are similar to conventional pulverized coal-fired plants except they operate at slightly 

higher temperatures and higher pressures, which allows for greater thermal efficiency. 

Supercritical coal-fired plants are commercially proven and represent an increasing proportion 

of new coal-fired power plants. A coal-fired plant is assumed to have a capacity factor of 

85 percent. 

The review team also considered an integrated gasification combined cycle (IGCC) coal-fired 

plant. IGCC is an emerging technology for generating electricity with coal that combines 

modern coal gasification technology with both gas turbine and steam turbine power generation. 

The technology is cleaner than conventional pulverized coal plants because major pollutants 

can be removed from the gas stream before combustion. The IGCC alternative also generates 

less solid waste than the pulverized coal-fired alternative. The largest solid waste stream 

produced by IGCC installations is slag, a black, glassy, sand-like material that is potentially a 

marketable byproduct. The other large-volume byproduct produced by IGCC plants is sulfur, 

which is extracted during the gasification process and can be marketed rather than placed in a 
Environmental Impacts of Alternatives 

NUREG-1937 9-8 February 2011 

landfill. IGCC units do not produce ash or scrubber wastes. In spite of the preceding 

advantages, the review team concludes that, at present, a new IGCC plant is not a reasonable 

alternative to a 2700 MW(e) nuclear power generation facility for the following reasons: 

(1) IGCC plants are more expensive than comparable pulverized coal plants (NETL 2007); 

(2) the two existing IGCC plants in the United States have considerably smaller capacity, 

approximately 250 MW(e) each, than the proposed 2700-MW(e) nuclear plant; (3) system 

reliability of existing IGCC plants has been lower than pulverized coal plants; (4) the existing 

IGCC plants have had an extended (though ultimately successful) operational testing period 

(NPCC 2005); and (5) a lack of overall plant performance warranties for IGCC plants has 

hindered commercial financing (NPCC 2005). For these reasons, IGCC plants are not 

considered further in this EIS. 

The review team assumed that coal and lime (calcium oxide or calcium hydroxide) or limestone 

(calcium carbonate) for a supercritical pulverized coal-fired plant would be delivered to the plant 

by train. STPNOC estimates that the plant would consume approximately 11 million tons/yr of 

pulverized sub-bituminous coal with an ash content of 3.9 percent (STPNOC 2010a). Lime or 

limestone, used in the scrubbing process for control of sulfur dioxide (SO2) emissions, is 

injected as a slurry into the hot effluent combustion gases to remove entrained SO2. The limebased scrubbing solution reacts with SO2 to form calcium sulfite, which precipitates and is 

removed from the process as sludge. STPNOC estimates that approximately 105,000 tons/yr of 

limestone would be used for flue gas desulfurization (STPNOC 2010a). 

Air Quality 

The impacts on air quality from coal-fired generation would vary considerably from those of 

nuclear generation because of emissions of SO2, nitrogen oxides (NOx), carbon monoxide (CO), 

particulate matter (PM), volatile organic compounds (VOCs), and hazardous air pollutants such 

as mercury and lead. In its environmental report (ER), STPNOC assumed a coal-fired plant 

design that would minimize air emissions through a combination of boiler technology and postcombustion pollutant removal. STPNOC estimated that annual emissions for a supercritical 

pulverized coal-fired generation alternative using sub-bituminous coal would be approximately 

as follows (STPNOC 2010a): 

• SO2 – 2900 tons/yr 

• NOx – 2000 tons/yr 

• CO – 2800 tons/yr 

• PM10 – 50 tons/yr 

• PM2.5 – 13 tons/yr 

• Mercury – 0.46 tons/yr. 

PM10 is particulate matter with a diameter equal to or less than 10 microns (40 CFR 50.6). 

PM2.5 is particulate matter with a diameter equal to or less than 2.5 microns (40 CFR 50.7). 
Environmental Impacts of Alternatives 

February 2011 9-9 NUREG-1937 

Based on data from previous NRC EIS documents, the review team determined the preceding 

emission estimates are reasonable. A new coal-fired plant at the STP site would also have 

approximately 27,000,000 tons/yr of carbon dioxide emissions (STPNOC 2010a) that could 

affect climate change. 

The acid rain requirements of the Clean Air Act capped the nation’s SO2 emissions from power 

plants. STPNOC would need to obtain sufficient pollution credits either from a set-aside pool or 

purchases on the open market to cover annual emissions from the plant. 

A new coal-fired generation plant at the STP site would likely need a prevention of significant 

deterioration (PSD) permit and an operating permit from the Texas Commission on 

Environmental Quality (TCEQ). The plant would need to comply with the new source 

performance standards for such plants in 40 CFR 60, Subpart Da. The standards establish 

emission limits for PM and opacity (40 CFR 60.42Da), SO2 (40 CFR 60.43Da), NOx

(40 CFR 60.44Da), and mercury (40 CFR 60.45Da). 

Fugitive dust emissions from construction activities would be mitigated using best management 

practices (BMPs); such emissions would be temporary (STPNOC 2010a). 

The U.S. Environmental Protection Agency (EPA) has various regulatory requirements for 

visibility protection in 40 CFR Part 51, Subpart P, including a specific requirement for review of 

any new major stationary source in areas designated as in attainment or unclassified under the 

Clean Air Act. The STP site is in an area designated as in attainment or unclassified for criteria 

pollutants (40 CFR 81.344). 

Section 169A of the Clean Air Act (42 USC 7491) establishes a national goal of preventing 

future impairment of visibility and remedying existing impairment in mandatory Class I Federal 

areas when impairment is from air pollution caused by human activities. In addition, the EPA 

regulations provide that for each mandatory Class I Federal area located within a State, the 

State must establish goals that provide for reasonable progress toward achieving natural 

visibility conditions. The reasonable progress goals must provide for an improvement in visibility 

for the most impaired days over the period of the implementation plan and confirm no 

degradation in visibility for the least-impaired days over the same period (40 CFR 51.308(d)(1)). 

If a new coal-fired power plant were located close to a mandatory Class I area, additional air 

pollution control requirements could be imposed. No mandatory Class I Federal areas are 

within 50 mi of the STP site. 

The GEIS for license renewal considers global warming from unregulated carbon dioxide 

emissions and acid rain from sulfur oxides and nitrogen oxide emissions as a potential impact 

(NRC 1996). Adverse human health effects, such as cancer and emphysema, have been 

associated with the byproducts of coal combustion. Overall, the review team concludes that air 
Environmental Impacts of Alternatives 

NUREG-1937 9-10 February 2011 

quality impacts from new coal-fired power generation at the STP site would be MODERATE. 

The impacts would be clearly noticeable, but would not destabilize air quality. 

Waste Management 

As the NRC has described in NUREG-1437 (NRC 1996) and verified during its preparation of 

the operating license renewal supplemental EIS analyses, coal combustion generates waste in 

the form of ash, and equipment for controlling air pollution generates additional ash, spent 

selective catalytic reduction (SCR) catalyst, and scrubber sludge. STPNOC estimated that a 

coal-fired plant would generate approximately 435,000 tons/yr of ash (STPNOC 2010a). 

STPNOC estimated that approximately 50 percent of the ash would be recycled 

(STPNOC 2008a). The coal plant would also generate approximately 124,000 tons/yr of 

scrubber sludge. STPNOC estimated that landfill disposal of the ash and scrubber sludge over 

a 40-year plant life would require approximately 141 ac (STPNOC 2010a). 

In May 2000, the EPA issued a “Notice of Regulatory Determination on Wastes from the 

Combustion of Fossil Fuels” (65 FR 32214). The EPA concluded that some form of national 

regulation is warranted to address coal combustion waste products because of health concerns. 

Accordingly, the EPA announced its intention to issue regulations for disposal of coalcombustion waste under Subtitle D of the Resource Conservation and Recovery Act (RCRA). 

EPA issued a proposed rule on June 21, 2010 (75 FR 35127) to regulate coal combustion 

residuals under RCRA. 

Waste impacts on groundwater and surface water could extend beyond the operating life of the 

plant if leachate and runoff from the waste storage area occurs. Disposal of the waste could 

noticeably affect land use (because of the acreage needed for waste) and groundwater quality, 

but with appropriate management and monitoring, it would not destabilize any resources. After 

closure of the waste site and revegetation, the land could be available for other uses. 

Construction-related debris would be generated during plant construction activities, and would 

be disposed of in approved landfills. 

For the reasons stated above, the review team concludes that the impacts from waste 

generated at a coal-fired plant would be MODERATE. The impacts would be clearly noticeable 

but would not destabilize any important resource. 

Human Health 

Coal-fired power generation introduces worker risks from coal and limestone mining, worker and 

public risk from coal and lime/limestone transportation, worker and public risk from disposal of 

coal-combustion waste, and public risk from inhalation of stack emissions. In addition, the 

discharges of uranium and thorium from coal-fired plants can potentially produce radiological 

doses in excess of those arising from nuclear power plant operations (Gabbard 1993). 
Environmental Impacts of Alternatives 

February 2011 9-11 NUREG-1937 

Regulatory agencies, including the EPA and State agencies, base air emission standards and 

requirements on human health impacts. These agencies also impose site-specific emission 

limits as needed to protect human health. Given the regulatory oversight exercised by the EPA 

and State agencies, the review team concludes that the human health impacts from radiological 

doses and inhaled toxins and particulates generated from coal-fired generation would be 

SMALL. 

Other Impacts 

Approximately 576 ac would need to be converted to industrial use on the STP site for the 

power block, infrastructure and support facilities, coal and limestone storage and handling, and 

landfill disposal of ash and scrubber sludge (STPNOC 2010a). Land-use changes would also 

occur offsite in an undetermined coal mining area to supply coal for the plant. In NUREG-1437, 

the staff estimated that approximately 22,000 ac would be needed for coal mining and waste 

disposal to supply a 1000 MW(e) coal-fired power plant over its operating life (59,400 ac for a 

2700 MW(e) plant) (NRC 1996). Based upon the amount of land affected for the site, mining, 

and waste disposal, the review team concludes that land-use impacts would be MODERATE. 

The amount of water used and the impacts on water use and quality from constructing and 

operating a coal-fired plant at the STP site would be comparable to those associated with a new 

nuclear plant. All discharges would be regulated by the TCEQ through a Texas Pollutant 

Discharge Elimination System (TPDES) permit. Indirectly, water quality could be affected by 

acids and mercury from air emissions. However, these emissions are regulated to minimize 

impacts. In NUREG-1437, the staff determined that some erosion and sedimentation would 

likely occur during construction of new facilities (NRC 1996). These impacts would be similar to 

those for a new nuclear plant. Overall, the review team concludes that the water-use and waterquality impacts would be SMALL. 

The coal-fired power generation alternative would introduce ecological impacts from 

construction and new incremental impacts from operations. The impacts would be similar to 

those of the proposed action at the STP site and along the transmission corridors. The impacts 

could include terrestrial and aquatic functional loss, habitat fragmentation and/or loss, reduced 

productivity, and a local reduction in biological diversity. The impacts could occur at the STP 

site and at the sites used for coal and limestone mining. Some of the impacts would occur in 

areas that were previously disturbed during the construction of STP Units 1 and 2, thereby 

limiting potential ecological effects. Stack emissions and disposal of waste products could 

affect aquatic and terrestrial resources. Additional impacts on threatened and endangered 

species could result from ash disposal and mining activities if the locations of such activities 

overlap with habitat for such protected species. Overall, the review team concludes that the 

ecological impacts would be MODERATE primarily because of potential impacts associated with 

disposal of ash and the large area of offsite land affected by mining activities. 
Environmental Impacts of Alternatives 

NUREG-1937 9-12 February 2011 

Socioeconomic impacts would result from the approximately 2400 workers needed to construct 

the plant and 315 workers to operate it, demands on housing and public services during 

construction, and the loss of jobs after construction (STPNOC 2010a). Overall, because the 

scale of activity for coal-fired power generation would be smaller than that for STP 3 and 4 but 

still significant in Matagorda County, the review team concludes that these impacts would be 

MODERATE and adverse in Matagorda County and SMALL and adverse elsewhere. The 

review team assumes that the owners of the alternative coal-fired units would pay significant 

property taxes to Matagorda County, the Matagorda County Hospital District, Navigation District 

#1, Drainage District #3, the Palacios Seawall District, and the Coastal Plains Groundwater 

Conservation District (CPGCD) (see Section 5.4.3.2). The review team estimates that the taxes 

would have a LARGE beneficial impact to the tax recipients. 

The four coal-fired power block units would be up to 200-ft high and visible offsite during 

daylight hours. The four exhaust stacks would be up to 600-ft high. The stacks and associated 

emissions would likely be visible in daylight hours for distances greater than 10 mi. The power 

block units and associated stacks would also be visible at night because of outside lighting. The 

Federal Aviation Administration (FAA) generally requires that all structures exceeding an overall 

height of 200 ft above ground level have markings and/or lighting so as not to impair aviation 

safety (FAA 2007). A mitigating factor is that the STP site is currently an industrial site located 

in a rural area. The visual impacts of a new coal-fired plant could be further mitigated by 

landscaping and color selection for buildings that is consistent with the environment. Visual 

impacts at night could be mitigated by reduced use of lighting, enhanced use of downfacinglighting provided the lighting meets FAA requirements, and appropriate use of shielding. 

Overall, the review team concludes that the aesthetic impacts associated with new coal-fired 

power generation at the STP site would be SMALL and adverse. 

Coal-fired power generation would introduce mechanical sources of noise that would likely be 

audible offsite. Sources contributing to the noise produced by plant operation are classified as 

continuous or intermittent. Continuous sources include the mechanical equipment associated 

with normal plant operations. Intermittent sources include the equipment related to coal 

handling, solid-waste disposal, transportation related to coal and limestone delivery, use of 

outside loudspeakers, and the commuting of plant employees. Noise impacts associated with 

rail delivery of coal and lime/limestone would be most significant for residents living in the 

vicinity of the facility and along the rail route. STPNOC estimated that about 17 unit trains of 

coal and limestone would be needed per week to supply a coal-fired plant (STPNOC 2010a). 

Although noise from passing trains significantly increases noise levels near the rail corridor, the 

short duration of the noise reduces the impacts. Nevertheless, given the frequency of train 

transport and the fact that many people are likely to be within hearing distance of the rail line, 

the review team concludes that the impacts of noise on residents in the vicinity of the facility and 

of the rail line would be MODERATE and adverse. 
Environmental Impacts of Alternatives 

February 2011 9-13 NUREG-1937 

As discussed in Section 2.6, minority and low-income persons are in the population near the 

STP site. However, the review team concludes that the socioeconomic-related environmental 

justice impacts on minority and low-income populations associated with a new coal-fired plant 

located at the STP site would likely be smaller than those associated with proposed nuclear 

Units 3 and 4 because the smaller scale of the building and operating effort. The air quality and 

noise impacts of a coal-fired power plant in Matagorda County are described above as 

MODERATE and adverse. Because at least one Asian-Pacific Islander population block group 

borders the STP site to the west and one small, possibly low-income settlement borders the 

STP site to the east, there is a potential for a disproportionate and adverse impact on minority 

and low-income populations. However, the area in the vicinity of the STP site is not a 

disproportionately minority or low-income area, and the air quality impacts likely would affect all 

nearby populations roughly equally. Furthermore, as discussed in Section 2.6.3, the review 

team did not identify any evidence of unique characteristics or practices in the minority and lowincome populations that may result in different air quality impacts compared to the general 

population (STPNOC 2010a; Scott and Niemeyer 2008). Therefore, although the review team 

determined the air quality impact of a coal-fired plant would be noticeable and adverse, the 

environmental justice impact would be SMALL. 

Historic and cultural resource impacts for a new coal-fired plant located at the STP site would be 

similar to the impacts for a new nuclear plant as discussed in Sections 4.6 and 5.6. A cultural 

resources inventory would likely be needed for any onsite property that has not been previously 

surveyed. Other lands that would be acquired to support the plant would also likely need an 

inventory of field cultural resources, identification and recording of existing historic and 

archaeological resources, and possible mitigation of the adverse impact from ground-disturbing 

actions. The studies would likely be needed for all areas of potential disturbance at the plant 

site; any offsite affected areas, such as mining and waste-disposal sites; and along associated 

corridors where new construction would occur, such as roads. The review team concludes that 

the historic and cultural resource impacts would likely be SMALL. 

The review team’s characterizations of the construction and operation impacts of new coal-fired 

power generation at the STP site are summarized in Table 9-1. 

9.2.2.2 Natural Gas-Fired Generation 

For the natural gas alternative, the review team assumed construction and operation of a 

natural gas-fired plant located at the STP site. The review team assumed that the plant would 

use combined-cycle combustion turbines, which is consistent with STPNOC’s ER. The review 

team used the assumption in the ER of four units with a net capacity of 675 MW(e) per unit 

(STPNOC 2010a). The natural gas-fired plant is assumed to have an operating life of 40 years. 

STPNOC estimated that the natural gas-fired plant would use approximately 121 billion 

standard cubic feet of natural gas per year (STPNOC 2010a). 
Environmental Impacts of Alternatives 

NUREG-1937 9-14 February 2011 

Table 9-1. Summary of Environmental Impacts of Coal-Fired Power Generation

Impact Category Impact Comment

Land use MODERATE Uses approximately 576 ac for the power block, infrastructure 

and support facilities, coal and limestone storage and handling, 

and landfill disposal of ash and scrubber sludge. Mining 

activities would have additional impacts to tens of thousands of 

ac offsite. 

Air quality MODERATE Emissions would be approximately: 

SO2 – 2900 tons/yr 

NOx – 2000 tons/yr 

CO – 2800 tons/yr 

Hg – 0.46 tons/yr 

PM10 – 50 tons/yr 

PM2.5 – 13 tons/yr 

CO2 – 27,000,000 tons/yr 

Water use and quality SMALL Impacts would be comparable to the impacts for new nuclear 

generating units located at the STP site. 

Ecology MODERATE Impacts could include terrestrial and aquatic functional loss, 

habitat fragmentation and/or loss, reduced productivity, and a 

local reduction in biological diversity. Impacts could occur at 

the STP site and vicinity and at the sites used for coal and 

limestone mining. Disposal of ash could affect the terrestrial 

and aquatic environments. Additional impacts on threatened 

and endangered species could result from ash disposal and 

mining activities. 

Waste management MODERATE Total waste volume would be approximately 435,000 tons/yr of 

ash and an additional 124,000 tons/yr of scrubber sludge. 

Socioeconomics LARGE 

Beneficial to 

MODERATE 

Adverse 

Impacts related to building the facilities would be noticeable. 

Local property tax base would benefit mainly during 

operations. Depending on where the workforce lives, the 

building-related impacts would be noticeable or minor. 

Impacts of coal transportation during operation would be 

noticeable. The plant would have noticeable aesthetic 

impacts. Some offsite noise impacts would occur. 

Human health SMALL Regulatory controls and oversight are assumed to be 

protective of human health. 

Historic and cultural 

resources 

SMALL Any potential impacts could likely be effectively managed. 

Most of the facility and infrastructure would be built on 

previously disturbed ground. 

Environmental justice SMALL There are minority and low-income persons in the local 

population; air quality and noise impacts to two populations 

could be noticeable but not disproportionate. 
Environmental Impacts of Alternatives 

February 2011 9-15 NUREG-1937 

Air Quality 

Natural gas is a relatively clean-burning fuel. When compared to a coal-fired plant, a natural 

gas-fired plant would release similar types of emissions but in lower quantities. A new natural 

gas-fired power generation plant would likely need a PSD permit and an operating permit from 

the TCEQ. A new natural gas-fired combined-cycle plant would also be subject to the new 

source performance standards in 40 CFR 60, Subparts Da and GG. These regulations 

establish emission limits for particulates, opacity, SO2, and NOX. The EPA has various 

regulatory requirements for visibility protection in 40 CFR 51, Subpart P, including a specific 

requirement for review of any new major stationary source in areas designated as in attainment 

or unclassified under the Clean Air Act. The STP site is in an area designated as in attainment 

or unclassified for criteria pollutants (40 CFR 81.344). 

Section 169A of the Clean Air Act (42 USC 7491) establishes a national goal of preventing 

future impairment of visibility and remedying existing impairment in mandatory Class I Federal 

areas when impairment is from air pollution caused by human activities. In addition, the EPA 

regulations provide that for each mandatory Class I Federal area located within a State, the 

State must establish goals that provide for reasonable progress toward achieving natural 

visibility conditions. The reasonable progress goals must provide for an improvement in visibility 

for the most impaired days over the period of the implementation plan and ensure no 

degradation in visibility for the least-impaired days over the same period (40 CFR 51.308(d)(1)). 

If a new natural gas-fired power plant were located close to a mandatory Class I area, additional 

air pollution control requirements could be imposed. No mandatory Class I Federal areas are 

within 50 mi of the STP site. 

STPNOC estimated that a natural gas-fired plant equipped with pollution control technology to 

meet emission limits would have approximately the following emissions (STPNOC 2010a): 

• SO2 – 41 tons/yr 

• NOx – 680 tons/yr 

• CO – 141 tons/yr 

• PM2.5 – 119 tons/yr. 

Based on data from previous NRC EIS documents, the review team determined the preceding 

emission estimates are reasonable. A natural gas-fired power plant would also have 

approximately 6,900,000 tons/yr of carbon dioxide emissions (STPNOC 2010a) that could affect 

climate change. 

The combustion turbine portion of the combined-cycle plant would be subject to EPA’s National 

Emission Standards for Hazardous Air Pollutants for Stationary Combustion Turbines 

(40 CFR 63) if the site is a major source of hazardous air pollutants. Major sources have the 
Environmental Impacts of Alternatives 

NUREG-1937 9-16 February 2011 

potential to emit 10 tons/yr or more of any single hazardous air pollutant or 25 tons/yr or more of 

any combination of hazardous air pollutants (40 CFR 63.6085(b)). 

The review team assumes fugitive dust emissions from construction activities would be 

mitigated using BMPs, similar to mitigation discussed in Chapter 4 for proposed Units 3 and 4. 

Such emissions would be temporary. 

The impacts of emissions from a natural gas-fired power generation plant would be clearly 

noticeable, but would not be sufficient to destabilize air resources. Overall, the review team 

concludes that air quality impacts resulting from construction and operation of new natural gasfired power generation at the STP site would be SMALL to MODERATE. 

Waste Management 

In NUREG-1437, the NRC staff concluded that waste generation from natural gas-fired 

technology would be minimal (NRC 1996). The only significant waste generated at a natural 

gas-fired power plant would be spent SCR catalyst, which is used to control NOx emissions. 

The spent catalyst would be regenerated or disposed of offsite. Other than spent SCR catalyst, 

waste generation at an operating natural gas-fired plant would be limited largely to typical 

operations and maintenance waste. Construction-related debris would be generated during 

construction activities. Overall, the review team concludes that waste impacts from natural gasfired power generation would be SMALL. 

Human Health 

Natural gas fired power generation introduces public risk from inhalation of gaseous emissions. 

The risk may be attributable to NOx emissions that contribute to ozone formation, which in turn 

contribute to health risk. Regulatory agencies, including the EPA and state agencies, base air 

emission standards and requirements on human health impacts. These agencies also impose 

site-specific emission limits as needed to protect human health. Given the regulatory oversight 

exercised by the EPA and State agencies, the review team concludes that the human health 

impacts from natural gas-fired power generation would be SMALL. 

Other Impacts 

A natural gas-fired generating plant would require approximately 107 ac for the power-block and 

support facilities (STPNOC 2010a). Construction of a natural gas pipeline from the STP site to 

the closest natural gas distribution line, located approximately 2 mi northwest of the site, would 

require approximately 18 ac. Thus, the total land commitment, not including natural gas wells 

and collection stations, would be approximately 125 ac. A small amount of additional land 
Environmental Impacts of Alternatives 

February 2011 9-17 NUREG-1937 

would also be required for natural gas wells and collection stations. Overall, the review team 

concludes that the land-use impacts from new natural gas-fired power generation at the STP 

site would be SMALL. 

The amount of water used and the impacts on water use and quality from constructing and 

operating a natural gas-fired plant at the STP site would be less than the impacts associated 

with building and operating a new nuclear facility. The impacts on water quality from 

sedimentation during construction of a natural gas-fired plant were characterized in 

NUREG-1437 as SMALL (NRC 1996). The NRC staff also noted in NUREG-1437 that the 

impacts on water quality from operations would be similar to, or less than, the impacts from 

other generating technologies (NRC 1996). Overall, the review team concludes that impacts on 

water use and quality would be SMALL. 

A natural gas-fired plant at the STP site would have less extensive ecological impacts than a 

new nuclear facility because less land would be affected. Much of the impact would occur in 

areas that were previously disturbed during the construction of STP Units 1 and 2. Constructing 

a new underground gas pipeline to the site would result in permanent loss of some terrestrial 

and aquatic function and conversion and fragmentation of habitat; however, assuming that the 

distance required to connect to natural gas distribution systems would be minimal, no important 

ecological attributes would be noticeably altered. Impacts on threatened and endangered 

species would be similar to the impacts from a new nuclear facility located at the STP site. 

Overall, the review team concludes that ecological impacts from a natural gas-fired plant at the 

STP site would be SMALL. 

Socioeconomic impacts would result from the approximately 661 workers needed to build the 

plant and 91 workers needed to operate it, demands on housing and public services during 

construction, and the loss of jobs after construction (STPNOC 2010a). Overall, the review team 

concludes these impacts would be SMALL and adverse for demographics, public services, 

education, traffic, and housing because of the mitigating influence of the site’s proximity to the 

surrounding population area and the relatively small number of workers needed to build and 

operate the plant in comparison to nuclear and coal-fired generation alternatives. The review 

team assumes that the owners would pay significant property taxes for the alternative natural 

gas-fired plant to Matagorda County, the Matagorda County Hospital District, Navigation District 

#1, Drainage District #3, the Palacios Seawall District, and the CPGCD (see Section 5.4.3.2) 

and would employ a noticeable but not significant number of workers, especially during the 

building period. Based on the expected valuation of a natural gas plant, which would be 

significantly less than for nuclear or coal, the property taxes would be lower for the natural gas 

option. Considering the population and economic condition of the County, the review team 

concludes that the taxes and employment would have a MODERATE beneficial impact on the 

County. 
Environmental Impacts of Alternatives 

NUREG-1937 9-18 February 2011 

Other socioeconomic impacts related to construction and operation would be SMALL. In most 

cases, the impacts would not likely be detectable, and certainly would not destabilize any 

important attribute of the resource involved. 

The turbine buildings, four exhaust stacks (approximately 200 ft high) and associated 

emissions, and the gas pipeline compressors would be visible during daylight hours from offsite. 

Noise and light from the plant would be detectable offsite. A mitigating factor is the STP site is 

currently an industrial site located in a rural area. Overall, the review team concludes that the 

aesthetic impacts associated with new natural gas-fired power generation at the STP site would 

be SMALL and adverse. 

Historic and cultural resource impacts for a new natural gas-fired plant located at the STP site 

would be similar to the impacts for a new nuclear plant as discussed in Sections 4.6 and 5.6. 

A cultural resources inventory would likely be needed for any onsite property that has not been 

previously surveyed. Other lands that would be acquired to support the plant would also likely 

need an inventory of field cultural resources, identification and recording of existing historic and 

archaeological resources, and possible mitigation of the adverse impact from ground-disturbing 

actions. The studies would likely be needed for all areas of potential disturbance at the plant 

site; any offsite affected areas, such as gas wells, collection stations, and waste disposal sites; 

and along associated corridors where new construction would occur, such as roads and a new 

pipeline. The review team concludes that the historic and cultural resource impacts associated 

with new natural gas-fired power generation at the STP site would be SMALL. 

As described in Section 2.6, there are minority and low-income persons in the population 

around the STP site. However, the review team concludes that the impacts of a natural gasfired plant at the STP site on minority or low-income populations would likely be much smaller 

than those associated with nuclear Units 3 and 4 because of the smaller scale of the building 

and operating effort. The air quality impacts of a natural gas-fired power plant in Matagorda 

County are described as SMALL to MODERATE and adverse. Similar to the situation with an 

alternative coal-fired power plant at the STP site, there is potential for the Asian-Pacific Islander 

population block group on the west side of the STP site and the small, possibly low-income 

settlement on the east to experience a SMALL to MODERATE adverse impact. However, the 

area in the vicinity of the STP site is not a disproportionately minority or low-income area, and 

the air quality impacts likely would affect all nearby populations roughly equally. Furthermore, 

as discussed in Section 2.6.3, the staff did not identify any evidence of unique characteristics or 

practices in the minority and low-income populations that may result in different air quality 

impacts compared to the general population (STPNOC 2010a; Scott and Niemeyer 2008). 

Therefore, although the review team determined the air quality impact of a natural gas-fired 

plant could be noticeable and adverse, the environmental justice impact would be SMALL. The 

review team’s characterization of the construction and operational impacts of natural gas-fired 

power generation at the STP site are summarized in Table 9-2. 
Environmental Impacts of Alternatives 

February 2011 9-19 NUREG-1937 

Table 9-2. Summary of Environmental Impacts of Natural Gas-Fired Power Generation 

Impact Category Impact Comment

Land use SMALL Approximately 125 ac would be needed for the power-block and 

support systems and connection to a natural gas pipeline. 

Air quality SMALL to 

MODERATE 

Emissions would be approximately: 

SO2 – 41 tons/yr 

NOx – 680 tons/yr 

CO – 141 tons/yr 

PM2.5 – 119 tons/yr 

CO2 – 6.9 million tons/yr. 

Water use and 

quality 

SMALL Impacts would be somewhat less than the impacts for new 

nuclear generating units located at the STP site. 

Ecology SMALL Constructing a new underground gas pipeline to the site would 

result in some permanent loss of terrestrial and aquatic function 

and conversion and fragmentation of habitat. Impacts on 

threatened and endangered species would be similar to the 

impacts from new nuclear generating units. In forested areas, 

impacts from pipeline construction would cause conversion of 

forested areas to herbaceous growth, resulting in net loss of 

function. 

Waste 

management 

SMALL The only significant waste would be from spent SCR catalyst 

used for control of NOx emissions. 

Socioeconomics MODERATE 

Beneficial to 

SMALL 

Adverse 

Construction and operations workforces would be relatively 

small. Addition to property tax base, while smaller than for a 

nuclear or coal-fired plant, might still be quite noticeable. 

Construction-related beneficial economic impacts would be 

noticeable, but there likely would not be noticeable adverse 

impacts on community services or infrastructure because of the 

relatively small numbers of in-migrants. Impacts during 

operation would be minor because of the small work-force 

involved. The plant would have only minor aesthetic impacts. 

Human health SMALL Regulatory controls and oversight are assumed to be protective 

of human health. 

Historic and 

cultural 

resources 

SMALL Any potential impacts could likely be effectively managed. Most 

of the facility and infrastructure would be built on previously 

disturbed ground. 

Environmental 

justice 

SMALL There are minority and low-income persons in the local 

population; air quality impacts to two populations could be 

noticeable but not disproportionate. 

9.2.3 Other Alternatives 

This section discusses other energy alternatives, the review team’s conclusions about the 

feasibility of each alternative, and the review team’s basis for the conclusions. New nuclear 

units at the STP site would be baseload generation units. Any feasible alternative to the new 
Environmental Impacts of Alternatives 

NUREG-1937 9-20 February 2011 

units would need to generate baseload power. In evaluating other energy technologies, 

STPNOC used the technologies discussed in NUREG-1937 (NRC 1996). The review team 

reviewed the information submitted by STPNOC in its ER and also conducted an independent 

review. The review team determined that the other energy alternatives are not reasonable 

alternatives to two new nuclear units that would provide baseload power. 

The review team has not assigned significance levels to the environmental impacts associated 

with the alternatives discussed in Section 9.2.3 because, in general, the generation alternatives 

would have to be installed at a location other than the STP site. Any attempt to assign 

significance levels would require the review team’s speculation about the unknown site. 

9.2.3.1 Oil-Fired Generation 

EIA’s reference case in its Updated Annual Energy Outlook 2009 projects that oil-fired power 

plants will not account for any new electric power generation capacity in the United States 

through the year 2030 (DOE/EIA 2009c). Oil-fired generation is more expensive than nuclear, 

natural gas-fired, or coal-fired generation options. In addition, future increases in oil prices are 

expected to make oil-fired generation increasingly more expensive. The high cost of oil has 

resulted in a decline in its use for electricity generation. In Section 8.3.11 of NUREG-1437, 

the staff estimated that construction of a 1000-MW(e) oil-fired plant would require about 120 ac 

of land (NRC 1996). Operation of an oil-fired powerplant would have environmental impacts 

that would be similar to those of a comparably sized coal-fired plant (see Section 9.2.2.1) 

(NRC 1996). 

For the preceding economic and environmental reasons, the review team concludes that an oilfired power plant located would not be a reasonable alternative to construction of a 2700 MW(e) 

nuclear power generation facility that would be operated as a baseload generation plant within 

STPNOC’s ROI. 

9.2.3.2 Wind Power 

Texas has significant wind energy resources and leads the Nation in wind-powered generation 

capacity (DOE/EIA 2009a). As discussed in Section 8.3, the installed wind capacity in the 

ERCOT region is approximately 9115 MW. Wind resource areas in the Texas Panhandle, along 

the Gulf Coast south of Galveston, and in the mountain passes and ridgetops of the TransPecos region offer some of the greatest wind power potential in the United States. The Horse 

Hollow Wind Energy Center in Texas is the largest wind farm in the world with a total capacity of 

735 MW(e) spread across approximately 47,000 ac in Taylor and Nolan Counties near Abilene 

in west-central Texas (TSECO 2008b). 

Newer wind turbines typically operate at approximately a 36 percent annual capacity factor 

(DOE 2008a). In comparison, the average capacity factor for a nuclear generation plant in 2008 
Environmental Impacts of Alternatives 

February 2011 9-21 NUREG-1937 

in the United States was 91.5 percent (NEI 2009). Wind turbines generally can serve as an 

intermittent power supply (NPCC 2005). Section 8.2 notes that the effective load carrying 

capability of wind is assumed by ERCOT to be 8.7 percent of name plate generation. Wind 

power, in conjunction with energy storage mechanisms such as pumped hydroelectric or 

compressed air energy storage (CAES), or another readily dispatchable power source, 

e.g., hydropower, might serve as a means of providing baseload power. 

EIA is not projecting any growth in pumped storage capacity through 2030 (DOE/EIA 2009c). In 

addition, the review team concludes in Section 9.2.3.4 that the potential for new hydroelectric 

development in Texas is limited. Therefore, the review team concludes that the use of pumped 

storage in combination with wind turbines to generate 2700 MW(e) is unlikely in the ERCOT 

region or Texas. 

A CAES plant consists of motor driven air compressors that use low cost off peak electricity to 

compress air into an underground storage medium. During high electricity demand periods, the 

stored energy is recovered by releasing the compressed air through a combustion turbine to 

generate electricity (NPCC 2009). Only two CAES plants are currently in operation. A 290-MW 

plant near Bremen, Germany, began operating in 1978, and a 110-MW plant located in 

McIntosh, Alabama, has been operating since 1991. Both facilities use salt caverns (Succar 

and Williams 2008). A CAES plant requires suitable geology such as an underground cavern 

for energy storage. A 268-MW CAES plant coupled to a wind farm, the Iowa Stored Energy 

Park, has been proposed for construction near Des Moines, Iowa. The facility would use a 

porous rock storage reservoir for the compressed air (Succar and Williams 2008). Other pilot, 

demonstration, prototype, and research projects involving CAES have been announced, 

including projects in California, New York, and Texas. In addition, projects such as the ConocoPhillips/General Compression venture may use compressed air storage directly, without the 

combustion of fuel such as natural gas. However, the review team is not aware of a CAES 

project approaching the scale of a 2700 MW(e) facility that has an announced construction date. 

Therefore, the review team concludes that the use of CAES in combination with wind turbines to 

generate 2700 MW(e) in the ERCOT region is unlikely. 

Construction and maintenance of land-based wind-energy facilities would alter ecosystem 

structure through vegetation clearing, soil disruption, and the potential for erosion. Aerodynamic 

and mechanical noise from wind turbines would affect wildlife. Collisions with wind turbines 

would increase bird and bat mortality. However, technological advances allow rotors to turn at 

lower speeds, reducing the potential for bird and bat strikes. 

A significant challenge for new wind power facilities is that wind farms can be built more quickly 

than transmission lines. It can take a year to build a wind farm, but five years to build the 

transmission lines needed to send power to cities. Moreover, wind power developers are 

reluctant to build where transmission lines do not yet exist, and utilities are equally reluctant to 

install transmission in areas that do not yet have power generators (TSECO 2008c). 
Environmental Impacts of Alternatives 

NUREG-1937 9-22 February 2011 

Southern Company and the Georgia Institute of Technology (GIT) studied the viability of 

offshore wind turbines in the southeast (Southern and GIT 2007). Among the conclusions of the 

study authors were the following: (1) the available wind data indicate that a wind farm located 

offshore of Georgia would likely have an adequate wind speed to support a project, although 

offshore project costs run approximately 50 to 100 percent higher than land-based systems; 

(2) based on current prices for wind turbines, the 20-year levelized cost of electricity produced 

from an offshore wind farm would be above the current production costs from existing power 

generation facilities; and (3) the current commercially available offshore wind turbines are not 

built to withstand major hurricanes above a Category 3 or a 1-min sustained wind speed of 

124 mph; and (4) the U.S. Department of Interior Minerals Management Service (MMS) has 

jurisdiction, as authorized in the Energy Policy Act of 2005, over alternatives energy-related 

projects on the outer continental shelf (OCS), including wind power developments. 

Wind potential varies along the U.S. Coast. Texas has a somewhat better offshore wind 

resource than Georgia (NREL 2010a), which suggests that the 20-year levelized cost of 

electricity could be less for a wind farm off the coast of Texas than a comparable wind farm off 

the coast of Georgia. Nevertheless, the review team believes that the preceding conclusions in 

the Southern/GIT report would generally apply to a wind farm located offshore of Texas based 

on similarities in the physical and regulatory environments. 

In its final “Programmatic EIS for Alternative Energy Development and Production and Alternate 

Uses of facilities on the Outer Continental Shelf” (MMS 2007), the MMS considered the potential 

environmental, social and economic impacts from wind energy (among other) projects on the 

OCS. The MMS indicated that the technologies used to extract energy on the OCS are “... 

relatively new and untested in the offshore environment of the OCS.” In developing the 

programmatic EIS, the MMS focused on “... those technologies that are likely to be initiated–for 

research, demonstration, or commercial scale—within the 5- to 7-year time frame.” In the 3 

years since the Programmatic EIS was finalized, no projects were initiated on the OCS. MMS 

(now the Bureau of Ocean Energy Management, Regulation and Enforcement) issued final 

regulations in April 2009 (74 FR 19638) to establish a program to grant leases, easements, and 

rights-of-way for renewable energy project activities on the outer continental shelf. 

The National Renewable Energy Laboratory (NREL) issued an analysis of “Large-Scale 

Offshore Wind Power in the United States—Assessment of Opportunities and Barriers” (NREL 

2010b). As NREL indicates “... the opportunities for offshore wind are abundant, yet the 

barriers and challenges are also significant. ... Technological needs are generally focused on 

making offshore wind technology economically feasible and reliable and expanding the resource 

area to accommodate more regional diversity for future U.S. offshore projects.” When energy 

policies mature and large-scale offshore wind energy projects become technically feasible, then 

it can play a significant role in future U.S. energy markets. 
Environmental Impacts of Alternatives 

February 2011 9-23 NUREG-1937 

The NREL report considers the wind energy potential and the proposed U.S. offshore wind 

projects and capacities. The Coastal Point Energy project (also called the Galveston Wind 

Project) off the Texas coast near Galveston (approximately 9 miles from shore) is anticipated to 

have a capacity of 300 MW(e) (NREL 2010b). No other wind energy projects were identified by 

NREL off the coast of Texas or its adjoining State (Louisiana). 

Although wind power is an important energy resource in the ERCOT region and Texas 

generally, the review team concludes that a wind energy facility at or in the vicinity of the STP 

site or elsewhere in STPNOC’s ROI would not currently be a reasonable alternative to 

construction of a 2700 MW(e) nuclear power generation facility within STPNOC’s ROI that 

would be operated as a baseload generation plant. 

9.2.3.3 Solar Power 

Solar technologies use energy and light from the sun to provide heating and cooling, light, hot 

water, and electricity for consumers. Solar energy can be converted to electricity using solar 

thermal technologies or photovoltaics. Solar thermal technologies employ concentrating 

devices to create temperatures suitable for power production. Concentrating thermal 

technologies are currently less costly than photovoltaics for bulk power production. They can 

also be provided with energy storage or auxiliary boilers to allow operation during periods when 

the sun is not shining (NPCC 2006). The largest operational solar thermal plant is the 

310 MW(e) Solar Energy Generating System located on approximately 1500 ac in the Mojave 

Desert in southern California (NextEra 2009). 

Solar radiation is available throughout Texas in sufficient quantity to power distributed solar 

systems such as solar water heaters and off-grid photovoltaic panels. Large solar power plants 

would be most cost-effective when sited in areas of west Texas that receive high levels of direct 

solar radiation (TSECO 2008a). 

Solar radiation has a low energy density relative to other common energy sources. 

Consequently a large total acreage is needed to gather an appreciable amount of energy. 

Typical solar-to-electric power plants require 5 to 10 ac for every MW of generating capacity 

(TSECO 2008a). For the target capacity of 2700 MW(e) for proposed Units 3 and 4, land 

requirements would thus be approximately 13,500 to 27,000 ac. Solar thermal electric 

technologies also typically require considerable water supplies. While the quantity of water 

needed per acre of use is similar to or less than that needed for irrigated agriculture, 

dependability of the water supply is an important issue in the sunny, dry areas of Texas that 

would be favored for large-scale solar power plants (TSECO 2008a). 

For a large solar plant to be practical as a baseload energy source, a means to store large 

quantities of energy for distribution when the plant is producing less than 2700 MW(e) would be 

needed. However, the storage possibilities are limited as discussed in Section 9.2.3.2. 
Environmental Impacts of Alternatives 

NUREG-1937 9-24 February 2011 

Because of the large amount of acreage required for comparable power generation and the 

limited energy storage availability, the review team concludes that solar energy facilities at or in 

the vicinity of the STP site would not currently be a reasonable alternative to construction of a 

2700 MW(e) nuclear power generation facility within STPNOC’s ROI that would be operated as 

a baseload generation plant. 

9.2.3.4 Hydropower 

Most of Texas does not lend itself to large-scale hydroelectric projects. Hydropower accounted 

for 0.7 percent of ERCOT’s electrical capacity in 2009 and only 0.2 percent of electricity actually 

produced within ERCOT in 2008 (ERCOT 2009a). While Texas has some identified potential 

for additional hydroelectric capacity, the likelihood of development is not high. Reservoirs can 

face opposition from the public and policy makers, and all new reservoirs being proposed in 

Texas by water planners are intended for storing water supplies (Texas Comptroller of Public 

Accounts 2008a). 

EIA’s reference case in its Updated Annual Energy Outlook 2009 projects that U.S. electricity 

production from hydropower plants will remain essentially stable through the year 2030 

(DOE/EIA 2009c). 

In NUREG-1437, the NRC staff estimated that land requirements for hydroelectric power are 

0.4 million ha (1 million ac) per 1000 MW(e) (NRC 1996). For the target capacity of 2700 MW(e) 

for proposed Units 3 and 4, land requirements would thus be 2.7 million ac. Aquatic organisms 

could become stranded temporarily when river levels are lowered. Temperature and nutrient 

stratification in the reservoir and reduced levels of dissolved oxygen could result in hypotoxic or 

anoxic conditions for aquatic organisms. Aquatic and riparian ecosystems downstream would be 

affected by a variety of dam-induced conditions, such as changes in sediment transport and 

deposition patterns, and channel erosion or scouring. Hydropower operations could enhance 

populations of nonnative aquatic biota and riparian plants. 

Because of the relatively low amount of undeveloped hydropower resources in Texas and the 

large land use and related environmental and ecological resource impacts associated with siting 

hydroelectric facilities large enough to produce 2700 MW(e), the review team concludes that 

local hydropower is not a feasible alternative to construction of a new nuclear power generation 

facility within STPNOC’s ROI that would be operated as a baseload generation plant. 

9.2.3.5 Geothermal Energy 

Hydrothermal resources, reservoirs of steam or hot water, are available primarily in the western 

states, Alaska, and Hawaii. However, earth energy can be tapped almost anywhere with 

geothermal heat pumps and direct-use applications. Other geothermal resources (e.g., hot, dry 

rock, and magma) are awaiting further technology development (DOE 2006). 
Environmental Impacts of Alternatives 

February 2011 9-25 NUREG-1937 

Texas does not have the sort of readily accessible, high-temperature hydrothermal resource 

that can be used to generate electricity (Virtus 2008). The resource in the central part of the 

State can, however, have an impact in low-temperature applications such as space heating or 

aquaculture. The geopressured-geothermal resource in Texas will become more attractive only 

in the context of higher energy prices. The potential of hot dry rock in Texas is presently 

unknown (Virtus 2008). 

Geothermal energy has an average capacity factor of 90 percent and can be used for baseload 

power where available. However, geothermal technology is not widely used as baseload power 

generation because of the limited geographic availability of the resource and immature status of 

the technology (NRC 1996). Geothermal systems have a relatively small footprint and minimal 

emissions (MIT 2006). A study led by the Massachusetts Institute of Technology concluded that 

a $300-$400 million investment over 15 years would be needed to make early-generation 

enhanced geothermal system power plant installations competitive in the evolving U.S. 

electricity supply markets (MIT 2006). 

Based on the limited geothermal energy resources currently available in Texas and immature 

status of the technology, the review team concludes that one or more geothermal energy 

facilities within STPNOC’s ROI would not currently be a reasonable alternative to construction of 

a 2700 MW(e) nuclear power generation facility within STPNOC’s ROI that would be operated 

as a baseload generation plant. 

9.2.3.6 Wood Waste 

In NUREG-1437, the NRC staff determined that a wood-burning facility can provide baseload 

power and operate with an average annual capacity factor of around 70 to 80 percent and with 

20 to 25 percent efficiency (NRC 1996). The fuels required are variable and site-specific. A 

significant impediment to the use of wood waste to generate electricity is the high cost of fuel 

delivery and high construction cost per megawatt of generating capacity. The larger woodwaste power plants are typically only 40 to 50 MW(e) in size. Estimates in NUREG-1437 

suggest that the overall level of construction impacts per megawatt of installed capacity would 

be approximately the same as that for a coal-fired plant, although facilities using wood waste for 

fuel would be built at smaller scales (NRC 1996). Similar to coal-fired plants, wood waste plants 

require large areas for fuel storage and processing and involve the same type of combustion 

equipment. The NRC staff has estimated that 400,000 to 800,000 ac could be affected to 

support a large wood waste plant (NRC 1996). 

A 100 MW(e) wood-fired biomass power plant being developed in Sacul, Texas, will use logging 

residue as its main fuel source, but also could use urban wood waste (Texas Comptroller of 

Public Accounts 2008b). The plant owner, Southern Power, estimates that the plant will require 

approximately 1 million tons of biomass per year, which it plans to procure within a 75-mi radius 

of the project site (Southern 2009). The plant is scheduled to come online in summer 2012. 
Environmental Impacts of Alternatives 

NUREG-1937 9-26 February 2011 

Because of uncertainties associated with obtaining sufficient wood and wood waste to fuel a 

baseload power plant, the ecological impacts of large-scale timber cutting (for example, soil 

erosion and loss of wildlife habitat), and the relatively small size of wood generation plants, the 

review team concludes that wood waste would not be a reasonable alternative in STPNOC’s 

ROI to a 2700 MW(e) nuclear power generation facility operated as a baseload generation 

plant. 

9.2.3.7 Municipal Solid Waste 

Municipal solid-waste combustors incinerate the waste and can use the resultant heat to 

produce steam, hot water, or electricity. The combustion process reduces the volume of waste 

and the need for new solid waste landfills. Mass burning technologies are most commonly used 

in the United States. This group of technologies processes raw municipal solid waste with little 

or no sizing, shredding, or separation before combustion. More than one-fifth of the 

U.S. municipal solid waste incinerators use refuse-derived fuel. In contrast to mass burning—

where the municipal solid waste is introduced "as is" into the combustion chamber—refusederived fuel facilities are equipped to recover recyclables (e.g., metals, cans, glass) followed by 

shredding the combustible fraction into fluff for incineration (EPA 2008). 

In NUREG-1437, the NRC staff determined that the initial capital cost for municipal solid-waste 

plants is greater than for comparable steam-turbine technology at wood-waste facilities because 

of the need for specialized waste-separation and waste-handling equipment for municipal solid 

waste (NRC 1996). 

Municipal solid-waste combustors generate SO2 and NOx emissions and an ash residue that is 

buried in landfills. The ash residue is composed of bottom ash and fly ash. Bottom ash refers 

to that portion of the unburned waste that falls to the bottom of the grate or furnace. Fly ash 

represents the small particles that rise from the furnace during the combustion process. Fly ash 

is generally removed from flue gases using fabric filters and/or scrubbers (EPA 2009a). 

Currently, approximately 87 waste-to-energy plants are operating in the United States 

(EPA 2009a). No plants are operating in Texas (Texas Comptroller of Public Accounts 2008c). 

The 87 plants generate approximately 2500 MW(e), or an average of approximately 29 MW(e) 

per plant (EPA 2009a). Given the small average output of existing plants, the review team 

concludes that generating electricity from municipal solid waste would not be a reasonable 

alternative to a 2700 MW(e) nuclear power generation facility operated as a baseload 

generation plant within STPNOC’s ROI. 

9.2.3.8 Other Biomass-Derived Fuels 

In addition to wood and municipal solid-waste fuel, several other biomass-derived fuels are 

available for fueling electric generators including burning crops, converting crops to a liquid fuel 

such as ethanol, and gasifying crops (including wood waste). EIA estimates that wind and 
Environmental Impacts of Alternatives 

February 2011 9-27 NUREG-1937 

biomass will be the largest source of renewable electricity generation among the 

nonhydropower renewable fuels through the year 2030 (DOE/EIA 2009c). However, in 

NUREG-1437, the NRC staff determined that none of these technologies has progressed to the 

point of being competitive on a large scale or of being reliable enough to replace a large 

baseload generating plant (NRC 1996). The major operating waste from biomass plants would 

be the fly ash and bottom ash that results from the combustion of the carbonaceous fuels. 

Biomass-fired plants have environmental impacts associated with the land used to grow the 

biomass. Such plants also have air emissions and can impact the aquatic environment. 

Currently, biomass energy accounts for less than 1 percent of electrical power production in 

Texas (Texas Comptroller of Public Accounts 2008d). 

Co-firing biomass with coal is possible when low-cost biomass resources are available. Co-firing 

is the most economic option for the near future to introduce new biomass power generation. 

These projects require small capital investments per unit of power generation capacity. Co-firing 

systems range in size from 1 to 30 MW(e) of biopower capacity (DOE 2008b). 

The review team concludes that given the relatively small average output of biomass generation 

facilities, biomass-derived fuels do not offer a reasonable alternative to a 2700 MW(e) nuclear 

power generation facility operated as a baseload generation plant within STPNOC’s ROI. 

9.2.3.9 Fuel Cells 

Fuel cells work without combustion and its associated environmental side effects. Power is 

produced electrochemically by passing a hydrogen-rich fuel over an anode, air over a cathode, 

and then separating the two by an electrolyte. The only byproducts are heat, water, and carbon 

dioxide. Hydrogen fuel can come from a variety of hydrocarbon resources by subjecting them to 

steam under pressure. Natural gas is typically used as the source of hydrogen. 

Phosphoric acid fuel cells are generally considered first-generation technology. Highertemperature, second-generation fuel cells achieve higher fuel-to-electricity and thermal 

efficiencies. The higher temperatures contribute to improved efficiencies and give the secondgeneration fuel cells the capability to generate steam for cogeneration and combined-cycle 

operations. 

During the past three decades, significant efforts have been made to develop more practical 

and affordable fuel cell designs for stationary power applications, but progress has been slow. 

The cost of fuel cell power systems must be reduced before they can be competitive with 

conventional technologies (DOE 2008c). 

The review team concludes that, at the present time, fuel cells are not economically or 

technologically competitive with other alternatives for baseload electricity generation. Future 

gains in cost competitiveness for fuel cells compared to other fuels are speculative. 
Environmental Impacts of Alternatives 

NUREG-1937 9-28 February 2011 

For the preceding reasons, the review team concludes that a fuel cell energy facility located in 

STPNOC’s ROI would not currently be a reasonable alternative to construction of a 2700 MW(e) 

nuclear power generation facility operated as a baseload generation plant. 

9.2.4 Combination of Alternatives 

Individual alternatives to the construction of one or more new nuclear units at the STP site might 

not be sufficient on their own to generate STPNOC’s target value of 2700 MW(e) because of the 

limited availability of the resource or lack of cost-effective opportunities. Nevertheless, it is 

conceivable that a combination of alternatives might be cost effective. There are many possible 

combinations of alternatives. It would not be reasonable to examine every possible combination 

of energy alternatives in an EIS. Doing so would be counter to CEQ guidance that an EIS 

should be analytic rather than encyclopedic, shall be kept concise, and shall be no longer than 

absolutely necessary to comply with NEPA and CEQ’s regulations [40 CFR 1502.2(a), (b)]. 

Given that STPNOC’s objective is for a new baseload generation facility, a fossil energy source, 

most likely coal or natural gas, would need to be a significant contributor to any reasonable 

alternative energy combination. 

Section 9.2.2.2 assumes the construction of four 675 MW(e) natural gas combined-cycle 

generating units at the STP site using the existing STP Main Cooling Reservoir (MCR). For a 

combined alternatives option, the review team assessed the environmental impacts of an 

assumed combination of three 675 MW(e) natural gas combined-cycle generating units at the 

STP site, and the following contributions from within STPNOC’s ROI: 50 MW(e) of hydropower 

(including a new reservoir), 250 MW(e) from biomass sources including municipal solid waste, 

175 MW(e) from additional conservation and demand-side management programs beyond what 

is currently planned, and 200 MW(e) from wind power. It is assumed that the demand-side 

management programs would be implemented by CPS Energy and/or Reliant Energy, a 

subsidiary of NRG Energy. Wind energy would need to be combined with an energy storage 

mechanism, such as CAES, to be a baseload resource. For wind power, 200 MW(e) equates to 

at least 500 to 600 MW(e) of installed capacitya coupled with a 200 MW(e) CAES plant. The 

review team included this contribution from wind even though generation with storage of this 

magnitude is not currently proposed, approved or under construction in Texas. 

The review team believes that the preceding contributions are reasonable and representative for 

STPNOC’s ROI. The contributions reflect the review team’s analysis in Section 9.2. A summary 

of the review team’s characterizations of the environmental impacts associated with the 

construction and operation of the preceding assumed combination of alternatives is in 

Table 9-3. 

 

a

 Note that this amount of capacity is based simply on the capacity factor of wind. It ignores the fact that there will be 

periods of low wind when power demand will exceed the storage capacity of the CAES facility, requiring some other 

source of electrical power to back up the wind/CAES combination. 
Environmental Impacts of Alternatives 

February 2011 9-29 NUREG-1937 

The review team also considered the result if wind generation coupled with storage was far 

greater than it assumed. If the wind contribution was quadrupled to 800 MW(e) of baseload 

power, equivalent to an installed capacity of at least 2000 to 2400 MW(e) with a 800-MW(e) 

CAES plant, the combination alternative would still require 1425 MW(e) from natural gas. Note 

that the CAES plant in this scenario is larger than any such facility worldwide. Also note that 

offshore wind capacity of this magnitude exceeds by a factor of 10 or more the amount of 

offshore wind projected by DOE (DOE/EIA 2010) for the entire United States by the year 2035. 

Under this scenario, the impact categorizations in Table 9-3 would not change, except that 

impacts to land use and ecology might become LARGE if onshore wind energy is used. If 

offshore wind is used, increased impacts to aquatic ecology are likely. In addition, the 

environmental impacts of this scenario are still greater than the impacts of the proposed action. 

So this scenario is not environmentally preferable. 

Table 9-3. Summary of Environmental Impacts of a Combination of Power Sources 

Impact Category Impact Comment

Land use MODERATE A natural gas-fired plant would have land-use impacts for the power 

block and connection to a natural gas pipeline. Wind, hydro, and 

biomass facilities and associated transmission lines would have 

land-use impacts in addition to the land-use impact of the natural 

gas-fired plant. Both offshore wind development and hydropower 

plants would potentially impede navigation. 

Air quality SMALL to 

MODERATE 

Emissions from the natural gas-fired plant would be approximately: 

SO2 – 31 tons/yr 

NOx – 510 tons/yr 

CO – 106 tons/yr 

PM2.5 – 89 tons/yr 

CO2 – 5,200,000 tons/yr 

Municipal solid waste and biomass generation facilities would also 

have emissions. 

Water use and 

quality 

SMALL Impacts would be somewhat less that the impacts for new nuclear 

generating units located at the STP site. 
Environmental Impacts of Alternatives 

NUREG-1937 9-30 February 2011 

Table 9-3. (contd) 

Impact Category Impact Comment

Ecology MODERATE Wind energy facilities in the Trans-Gulf migratory route could result 

in increased avian mortality and might also cause increased 

mortality of migratory and resident bats. Offshore wind power 

development would also affect avian and aquatic resources. 

Coastal bird populations could be subject to increased mortality. 

Hydropower facilities would affect terrestrial and aquatic habitat and 

species. 

Waste 

management 

SMALL to 

MODERATE 

The only significant waste would be from spent SCR catalyst used 

for control of NOx emissions and ash from biomass and municipal 

solid waste sources. 

Socioeconomics MODERATE 

Beneficial to 

SMALL 

Adverse 

Construction and operations workforces would be noticeable but 

not significant. Addition to property tax base, while smaller than for 

a nuclear or coal-fired plant, might still be quite noticeable. 

Construction-related beneficial economic impacts would be 

noticeable, but there likely would not be noticeable adverse impacts 

on community services or infrastructure because of the relatively 

small numbers of in-migrants. Impacts during operation would be 

minor because of the small workforce involved. The natural gasfired and biomass plants and wind turbines would have aesthetic 

impacts. 

Human health SMALL Regulatory controls and oversight are assumed to be protective of 

human health. 

Historic and 

cultural resources 

SMALL Any potential impacts could likely be effectively managed. Most of 

the facilities and infrastructure at the STP site would likely be built 

on previously disturbed ground. 

Environmental 

justice 

SMALL There are minority and low-income persons in the local population; 

air quality impacts to two populations could be noticeable but not 

disproportionate. 

9.2.5 Summary Comparison of Alternatives 

Table 9-4 contains a summary of the review team’s environmental impact characterizations for 

constructing and operating new nuclear, coal-fired, and natural gas-fired combined-cycle 

generating units at the STP site. The combination of alternatives shown in Table 9-4 assumes 

siting of natural gas combined-cycle generating units at the STP site and siting of other 

generating units within STPNOC’s ROI. The review team’s impact characterizations for the 

nuclear option in Table 9-4 reflect the nuclear fuel cycle impacts discussed in Chapter 6 of the 

EIS. 
Environmental Impacts of Alternatives 

February 2011 9-31 NUREG-1937 

Table 9-4. Summary of Environmental Impacts of Construction and Operation of New Nuclear, 

Coal-Fired, and Natural Gas-Fired Generating Units, and a Combination of 

Alternatives 

Resource Area Nuclear Coal Natural Gas

Combination of 

Alternatives

Land use SMALL MODERATE SMALL MODERATE 

Air quality (criteria pollutants) SMALL MODERATE SMALL to 

MODERATE 

SMALL to 

MODERATE 

Water use and quality SMALL SMALL SMALL SMALL 

Ecology SMALL MODERATE SMALL MODERATE 

Waste management SMALL MODERATE SMALL SMALL to 

MODERATE 

Socioeconomics LARGE 

Beneficial to 

MODERATE 

Adverse 

LARGE 

Beneficial to 

MODERATE 

Adverse 

MODERATE 

Beneficial to 

SMALL 

Adverse 

MODERATE 

Beneficial to 

SMALL Adverse 

Human health SMALL SMALL SMALL SMALL 

Historic and cultural resources SMALL SMALL SMALL SMALL 

Environmental justice SMALL SMALL SMALL SMALL 

The review team reviewed the available information on the environmental impacts of power 

generation alternatives compared to the building new nuclear units at the STP site. Based on 

this review, the review team concludes that, from an environmental perspective, none of the 

viable energy alternatives are clearly preferable to building a new baseload nuclear power 

generation plant at the STP site. 

Because of current concerns related to greenhouse gas emissions, it is appropriate to 

specifically discuss the differences among the alternative energy sources regarding carbon 

dioxide (CO2) emissions. The CO2 emissions for the proposed action and energy generation 

alternatives are discussed in Sections 5.7.1, 9.2.2.1, 9.2.2.2, and 9.2.4. Table 9-5 summarizes 

the CO2 emission estimates for a 40-year period for the alternatives considered by the review 

team to be viable for baseload power generation. These estimates are limited to the emissions 

from power generation and do not include CO2 emissions for workforce transportation, building, 

fuel-cycle, or decommissioning. Among the viable energy generation alternatives, the CO2

emissions for nuclear power are a small fraction of the emissions of the other viable energy 

generation alternatives. Even adding in the transportation emissions for the nuclear plant 

workforce and fuel cycle emissions would increase the emissions for plant operation over a 

40-year period to about 54,000,000 metric tons. This number is still significantly lower than the 

emissions for the other viable alternatives. 
Environmental Impacts of Alternatives 

NUREG-1937 9-32 February 2011 

Table 9-5. Comparison of Direct Carbon Dioxide Emissions for Energy Alternatives 

Generation Type Years 

CO2 Emission 

(metric tons) 

Nuclear Power(a) 40 380,000 

Coal-Fired Generation(b) 40 980,000,000 

Natural Gas-Fired Generation(c)

 40 250,000,000 

Combination of Alternatives(d) 40 190,000,000 

(a) From Section 5.7.1, value is for plant operation at two units. 

(b) From Section 9.2.2.1 

(c) From Section 9.2.2.2 

(d) From Section 9.2.4 (assuming only natural gas generation has significant CO2 emissions) 

On June 3, 2010, EPA issued a rule tailoring the applicability criteria that determine which 

stationary sources and modification to existing projects become subject to permitting 

requirements for greenhouse gas (GHG) emissions under the Prevention of Significant 

Deterioration (PSD) and Title V programs of the Clean Air Act (75 FR 31514). According to the 

Tailoring Rule, GHGs are a regulated new source review (NSR) pollutant under the PSD major 

source permitting program if the source (1) is otherwise subject to PSD (for another regulated 

NSR pollutant) and (2) has a GHG potential to emit equal to or greater than 75,000 tons per 

year of CO2 equivalent (“carbon dioxide equivalent” adjusting for different global warming 

potentials for different GHGs). Such sources would be subject to best available control 

technology (BACT). The use of BACT has the potential to reduce the amount of GHGs emitted 

from stationary source facilities. The implementation of this rule could reduce the amount of 

GHGs from the values indicated in Table 9-5 for coal and natural gas, as well as from other 

alternative energy sources that would otherwise have appreciable uncontrolled GHG emissions. 

The GHG emissions from the production of electricity from a nuclear power source are primarily 

from the fuel cycle and could be reduced further if the electricity from a fossil fuel source 

powering the fuel cycle was subject to BACT controls. The emission of GHGs from the 

production of electrical energy from a nuclear power source is orders of magnitude less than 

those of the reasonable alternative energy sources. Accordingly, the comparative relationship 

between the energy sources listed in Table 9-5 would not change meaningfully, even if the GHG 

emissions from the nuclear fuel cycle reductions are ignored, because GHG emissions from the 

other energy source alternatives would not be sufficiently reduced to make them 

environmentally preferable to the proposed project. 

The CO2 emissions associated with generation alternatives such as wind power, solar power, 

and hydropower would be associated with workforce transportation, construction, and 

decommissioning of the facilities. Because these generation alternatives do not involve 

combustion, the review team considers the emissions to be minor and concludes that the 

emissions would have a minimal cumulative impact. Other energy generation alternatives 

involving combustion of oil, wood waste, municipal solid waste, or biomass-derived fuels would 

have CO2 emissions from combustion as well as from workforce transportation, plant 
Environmental Impacts of Alternatives 

February 2011 9-33 NUREG-1937 

construction, and plant decommissioning. It is likely that the CO2 emissions from the 

combustion process for these alternatives would dominate the other CO2 emissions associated 

with the generation alternative. It is also likely that the CO2 emissions from these alternatives 

would be the same order of magnitude as the emissions for the fossil-fuel alternatives 

considered in Sections 9.2.2.1, 9.2.2.2, and 9.2.4. However, because the review team 

determined that these alternatives do not meet the need for baseload power generation, the 

review team has not evaluated the CO2 emissions quantitatively. 

As discussed in Chapter 8, the review team concludes that the need for additional baseload 

power generation has been demonstrated. Also, as discussed earlier in this chapter, the review 

team concludes that the viable alternatives to the proposed action all would involve the use of 

fossil fuels (coal or natural gas). Consequently, the review team concludes that the proposed 

action results in the lowest level of emissions of greenhouse gases among the viable 

alternatives. 

9.3 Alternative Sites 

9.3.1 Alternative Sites Selection Process 

NRC EISs prepared in conjunction with a COL application are to analyze alternatives to the 

proposed action (10 CFR 51.71(d)). This section discusses STPNOC’s process for selecting its 

proposed and alternative sites and the review team’s evaluation of the process. STPNOC’s site 

selection process was based on guidance in the following documents (STPNOC 2010a): NRC’s 

Environmental Standard Review Plan (ESRP) (NRC 2000), Regulatory Guide 4.7 (NRC 1998), 

and the Electric Power Research Institute’s (EPRI) Siting Guide (EPRI 2002). 

NRC’s site selection process guidance calls for identification of an ROI followed by successive 

screening to candidate areas, potential sites, candidate sites, and the proposed site (NRC 

2000). STPNOC modified this process somewhat by adding an extra step of screening to 

primary sites after it had identified potential sites. 

The review team raised a number of concerns related to STPNOC’s site selection process and 

associated results submitted by STPNOC in the COL application (through Revision 2 of the 

application). The questions were documented in requests for additional information from the 

NRC dated May 19, 2008 (NRC 2008a), and November 18, 2008 (NRC 2008b). As a result of 

these information requests, STPNOC revised its siting process and submitted it in Revision 3 to 

the ER (STPNOC 2009a) and in a separate Siting Report (STPNOC 2009b). The evaluation 

that follows is based on the revised site selection process documented in ER Revisions 3 and 4 

(STPNOC 2010a). 
Environmental Impacts of Alternatives 

NUREG-1937 9-34 February 2011 

9.3.1.1 Selection of Region of Interest 

The ROI is the geographic area considered by an applicant in searching for candidate areas 

and potential sites for a new nuclear power plant (NRC 2000). STPNOC selected the land area 

included in the ERCOT grid as its ROI (STPNOC 2010a). ERCOT manages the flow of electric 

power to approximately 20 million Texas customers, which represents approximately 85 percent 

of the State’s electric load and 75 percent of the Texas land area (see Figure 8-1) 

(ERCOT 2009b). ERCOT is further discussed in Section 8.1 of this EIS. 

9.3.1.2 Selection of Candidate Areas 

Candidate areas are one or more areas within an applicant’s ROI that remain after unsuitable 

areas for a new nuclear power plant (e.g., due to high population, lack of water, fault lines, or 

distance to transmission lines) have been removed (NRC 2000). To screen the ROI for 

potential candidate areas, STPNOC used the following screening criteria: geology/seismicity, 

water availability, population, dedicated lands, and ecology (STPNOC 2010a). STPNOC 

determined that there are no areas within STPNOC’s ROI with predicted peak ground 

accelerations greater than 0.3 g. Therefore, the related criteria had no effect on site selection. 

The water availability criterion was the most influential criterion STPNOC used in screening the 

ROI (STPNOC 2010a). STPNOC looked for rivers where cooling makeup water would not 

exceed 10 percent of the average flow rate. STPNOC also assumed that water from the Gulf of 

Mexico would be a viable source of cooling water makeup. Urban population areas and special 

use lands (e.g., parks) owned by a governmental entity were excluded. Land within a critical 

habitat for Federally listed endangered species was also excluded. Using its screening criteria, 

STPNOC selected the following nine candidate areas within its ROI (STPNOC 2010a): 

1. The Nueces River below Choke Canyon Reservoir – approximately 85 river mi. 

2. The Guadalupe River below New Braunfels and the San Antonio River below Goliad – 

approximately 320 river mi. 

3. The Colorado River below San Saba (just above Lake Buchanan) – approximately 

450 river mi. 

4. The Brazos River below South Bend (just above Possum Kingdom Lake) and the Little River 

below the town of Little River – approximately 685 river mi. 

5. The Trinity River below Dallas – approximately 200 river mi. 

6. The Neches River below Lake Palestine and the Angelina River below Alto – approximately 

185 river mi. 

7. The Sabine River below Mineola – approximately 60 river mi. 

 
Environmental Impacts of Alternatives 

February 2011 9-35 NUREG-1937 

8. The Sulphur River below Talco and the Red River below Burkburnett – approximately 

435 river mi. 

9. The Gulf Coast – approximately 230 coastal mi. 

The candidate areas are shown in Figure 9-1. 

Figure 9-1. Candidate Areas (STPNOC 2010a) 

 
Environmental Impacts of Alternatives 

NUREG-1937 9-36 February 2011 

9.3.1.3 Selection of Potential Sites 

Potential sites are those sites within a candidate area that have been identified by an applicant 

for preliminary assessment in establishing candidate sites (NRC 2000). STPNOC applied the 

following criteria in selecting potential sites (STPNOC 2010a): 

• Distance to existing rail lines: The distance to existing rail lines was minimized to the extent 

possible. 

• Distance to existing transmission lines: The distance to existing 345-kV transmission lines 

was minimized to the extent possible. 

• Distances from towns, villages, and developed areas (commercial and residential) were 

maximized. Developed areas were identified from regional screening, satellite imagery, and 

county and topographic maps. 

• Distance from industrial areas: The distance from industrial areas identifiable from the aerial 

photographs and topographic maps (e.g., airports and industrial complexes) was maximized 

except when an existing power plant site was being considered. 

• Water availability: STPNOC considered the following factors: 

– Proximity to cooling water supply: Distance to the potential cooling water source was 

minimized to extent possible. 

– Existing lakes or reservoirs: Whenever possible, lands around existing lakes and 

reservoirs were evaluated as possible potential sites. 

– Construction of new reservoirs: If existing lakes or reservoirs were not in areas of 

interest, the topography of the land was qualitatively evaluated for the construction of a 

new reservoir. 

• Topography: The optimal topography was assumed by STPNOC to be: (1) a relatively flat 

area, (2) above the 100-year floodplain, and (3) adjacent to streams with surrounding 

topography conducive to the construction of a reservoir. Topographic maps and aerial 

photographs were qualitatively examined to find areas as close to this ideal as possible. 

• Land use: Nominal site areas encompassing a consistent land-use pattern were considered 

most suitable, with preference to lands that showed no current development but signs of 

previous disturbance (e.g., recently timbered forest or pasture land). Such patterns were 

assumed to be associated with fewer landowners (preferred) and less challenges in land 

acquisition. Land owned by the applicant and known availability of land were not used as 

criteria. 

• Transportation: Access to the potential sites was qualitatively evaluated. Areas around 

major highways were avoided. Areas within a reasonable distance of state highways were 

considered. 
Environmental Impacts of Alternatives 

February 2011 9-37 NUREG-1937 

STPNOC identified 33 potential sites using professional judgment and the preceding criteria. 

The potential sites are shown in Figure 9-2. 

9.3.1.4 Selection of Primary Sites 

STPNOC screened its 33 potential sites to identify a smaller set of primary sites for more 

detailed evaluation. Criteria used in the screening included cooling water supply, flooding 

potential, population, hazardous land uses, ecology, wetlands, heavy haul access, transmission 

access, and land acquisition. The criteria were derived from a larger set of more detailed 

criteria in EPRI (2002) (STPNOC 2010a). 

STPNOC developed weighting factors reflecting the relative importance of each of the criteria. 

The factors were developed by a multi-disciplinary committee familiar with the subject area of 

nuclear power plant site suitability. The committee was comprised of subject matter experts in 

water use and availability, engineering and licensing, real estate, ecology and environment, 

transmission, land use, health and safety, geotechnical, socioeconomics, and public relations. 

The weighting factors were derived using a methodology consistent with the modified Delphi 

process specified in EPRI (2002) (STPNOC 2010a). 

STPNOC next assigned a rating of 1 to 5 (1 = least suitable; 5 = most suitable) for each criterion 

at each potential site. STPNOC’s information sources for assigning the ratings included publicly 

available data, information available from STPNOC files and personnel, and large scale satellite 

photographs. Composite suitability ratings reflecting the overall suitability of each potential site 

were then developed by multiplying the ratings by the criterion weight factors and summing over 

all criteria for each potential site (STPNOC 2010a). STPNOC’s results are shown in Figure 9-3 

(STPNOC 2010a). 
Environmental Impacts of Alternatives 

NUREG-1937 9-38 February 2011 

Figure 9-2. Potential Sites (STPNOC 2010a) 
Environmental Impacts of Alternatives 

February 2011 9-39 NUREG-1937 

Figure 9-3. Screening Criteria Evaluation Results (STPNOC 2010a) 

Based on the results, STPNOC selected the nine highest rated sites as its primary sites for 

further evaluation. The location of the nine primary sites is shown in Figure 9-4. 

9.3.1.5 Selection of Candidate Sites 

STPNOC screened its nine primary sites to identify four candidate sites. Candidate sites are 

those potential sites within the ROI that are considered in the comparative evaluation of sites to 

be among the best that can reasonably be found for the siting of a nuclear power plant 

(NRC 2000). 

In selecting candidate sites, STPNOC followed a similar, but more detailed, process to that used 

to identify primary sites. STPNOC derived more than 30 siting criteria from criteria in EPRI 

(2002). The criteria are listed in Table 9-6 (STPNOC 2009a). Weighting Factors were 

developed using the same process as STPNOC used for the screening of potential sites. The 

siting criteria and weighting factors used by STPNOC to screen primary sites to candidate sites 

were not the same as those used to screen potential sites to primary sites. 

Each primary site was assigned a rating of 1 to 5 (1 = least suitable; 5 = most suitable) for each 

of the siting criteria. Similar to the screening of potential sites, STPNOC’s information sources 

for assigning the ratings included publicly available data, information available from STPNOC 
Environmental Impacts of Alternatives 

NUREG-1937 9-40 February 2011 

Figure 9-4. Primary Sites (STPNOC 2010a) 
Environmental Impacts of Alternatives 

February 2011 9-41 NUREG-1937 

Table 9-6. Criteria for Selection of Candidate Sites 

Health and Safety Environmental Socioeconomic Engineering and Cost 

Accident cause related 

1. Geology and 

seismology 

2. Cooling system 

requirements 

3. Flooding potential 

4. Nearby hazardous land 

uses 

5. Extreme weather 

conditions 

Construction related 

effects on aquatic 

ecology 

1. Disruption of 

important species 

and habitats 

2. Bottom sediment 

disruption effects 

Construction 

related effects 

Health and Safety Related 

Criteria 

1. Water supply 

2. Pumping distance 

3. Flooding 

4. Civil works 

Accident effects 

1. Population 

2. Emergency planning 

3. Atmospheric dispersion 

Construction related 

effects on terrestrial 

ecology 

1. Disruption of 

wetlands and 

important species 

and habitats 

2. Dewatering effects 

on adjacent lands 

Environmental 

justice 

Transportation and 

transmission access 

1. Railroad 

2. Highway 

3. Barge 

4. Transmission 

Operational effects 

1. Surface water 

radionuclide pathway 

2. Groundwater 

radionuclide pathway 

3. Air radionuclide 

pathway 

4. Air food ingestion 

pathway 

5. Surface water food 

indigestion pathway 

6. Transportation safety 

Operational related 

effects on aquatic 

ecology 

1. Thermal discharge 

effects 

2. Entrainment and 

impingement 

effects 

3. Dredging and 

disposal effects 

Land use Socioeconomic and land 

use 

1. Topography 

2. Land rights 

3. Labor rates 

 Operational related 

effects on terrestrial 

ecology 

1. Drift effects on 

surrounding areas 

 

Source: STPNOC 2009a 
Environmental Impacts of Alternatives 

NUREG-1937 9-42 February 2011 

files and personnel, and large scale satellite photographs. Composite suitability ratings 

reflecting the overall suitability of each primary site were then developed by multiplying criterion 

ratings by the criterion weight factors and summing over all criteria for each site. STPNOC’s 

computed composite ratings for the nine primary sites are shown in Table 9-7 (STPNOC 

2010a). 

Table 9-7. Composite Ratings for the Primary Sites 

Site 

Composite 

Rating Score 

STP 735.4 

Red 2 611.8 

Allens Creek 597.5 

Colorado 3 595.8 

Trinity 2 590.1 

Guadalupe 2 586.0 

Malakoff 574.1 

Red 1 573.2 

Sulphur 1 539.9 

Source: STPNOC 2010a 

To provide additional insights on the environmental preferability of the nine primary sites, two 

additional indicators were used by STPNOC. 

• Environmental Site Rating –This rating consisted of the Health and Safety Criteria (minus 

the Geology/Seismology criterion), the Environmental Criteria, and the Socioeconomic 

Criteria. The top sites based on this rating were STP, Red 1, Red 2, Trinity 2, and Allens 

Creek/Guadalupe 2, with no significant difference between Allens Creek and Guadalupe 2. 

• Expanded Environmental Site Rating –This rating consisted of the Environmental Site 

Rating plus the Railroad Access and Transmission Access criteria, which reflect a rough 

proxy of environmental impact through measurement of the relative distances required for 

these support facilities. The top sites based on this rating were STP, Red 2, Trinity 2, 

and Allens Creek, with no significant difference between Allens Creek, Red 1, and 

Colorado 3. 

STPNOC’s evaluation showed that while the Colorado 3 site ranked fourth overall in composite 

rating, it did not rank as high in the environmentally related criteria ratings. In addition, the 

Guadalupe 2 site, ranked sixth in the composite ratings, but did not rank high in the 

environmentally related criteria. These two sites, along with the three lowest ranked sites, were 

eliminated by STPNOC from further consideration. Thus, the following sites were identified by 
Environmental Impacts of Alternatives 

February 2011 9-43 NUREG-1937 

STPNOC as its candidate sites: 

• STP 

• Red 2 

• Allens Creek 

• Trinity 2. 

STPNOC selected the STP site as its proposed site, relying on ESRP 9.3 (NRC 2000), which 

recognizes that there will be special cases in which the proposed site was not selected on the 

basis of a systematic site selection process. One example cited in ESRP 9.3 is the siting of a 

proposed nuclear plant on the site of an existing nuclear power plant previously found 

acceptable on the basis of a NEPA review. The proposed site is then compared to alternative 

sites identified through a systematic process. 

9.3.1.6 Evaluation of STPNOC’s Site Selection Process 

The review team evaluated the methodology used by STPNOC to select its proposed and 

alternative sites. The ROI selected by STPNOC covers a largely isolated grid system (ERCOT) 

that encompasses a large and ecologically varied area. Use of such an area is consistent with 

the guidance in ESRP 9.3 (NRC 2000). STPNOC then established candidate areas based on a 

group of exclusionary criteria similar to those described in ESRP 9.3. Next STPNOC identified 

potential sites within the candidate areas based on qualitative criteria, and then narrowed the list 

of sites using more detailed criteria to identify what it refers to as primary sites. Finally, 

STPNOC used more specific criteria to evaluate the primary sites and identify the alternative 

sites. Based on its review of STPNOC’s site selection process and the guidance in ESRP 9.3 

(NRC 2000), the review team concludes that STPNOC’s process for selecting its ROI, candidate 

areas, potential sites, primary sites, candidate sites, and the proposed STP site was reasonable 

and did not arbitrarily exclude locations that might be suitable choices for siting two new nuclear 

generating units to satisfy the need for power identified in Chapter 8. 

The three alternative sites examined in detail in Section 9.3 are the Red 2 site in Fannin County, 

the Allens Creek site in Austin County, and the Trinity 2 site in Freestone County. The review 

team visited each of the three alternative sites, as well as the proposed site. The review team 

used information in STPNOC’s ER related to the three alternative sites and also independently 

collected and analyzed reconnaissance-level information for each of the alternative sites using 

ESRP 9.3 (NRC 2000) as guidance. 

In the discussion of the alternative sites that follows, the review team evaluated cumulative 

impacts of building and operating two new nuclear units at each site for each resource category, 

considering the impacts of other nearby projects on that resource. Included in the cumulative 

analysis are past, present, and reasonably foreseeable Federal, non-Federal, and private 

actions that could have meaningful cumulative impacts with the proposed action. For purposes 
Environmental Impacts of Alternatives 

NUREG-1937 9-44 February 2011 

of this analysis, the past is defined as the time period before receipt of the COL application. 

The present is defined as the time period from the receipt of the COL application until the start 

of building proposed Units 3 and 4. The future is defined as the start of building Units 3 and 4 

through operation and eventual decommissioning. 

Using Chapter 7 as a guide, the specific resources and components that could be affected by 

the incremental effects of the proposed action if implemented at the alternative site and other 

actions in the same geographic area were identified. The affected environment that serves as 

the baseline for the cumulative impacts analysis is described for each alternative site and 

includes a qualitative discussion of the general effects of past actions. For each resource area, 

the geographic area over which past, present, and future actions could reasonably contribute to 

cumulative impacts is defined and described in later sections. The analysis for each resource 

area at each alternative site concludes with a cumulative impact finding (SMALL, MODERATE, 

or LARGE). For those cases in which the impact level to a resource was greater than SMALL, 

the review team also discussed whether building and operating the nuclear units would be a 

significant contributor to the cumulative impact. In the context of this evaluation, “significant” is 

defined as a contribution that is important in reaching that impact level determination. 

The nonradioactive waste impacts described in Sections 4.10 and 5.10 would not vary 

significantly from one site to another. The types and quantities of nonradioactive and mixed 

waste would be approximately the same for the construction and operation of two ABWR 

reactors at any of the alternative sites. For each alternative site, all wastes destined for landbased treatment or disposal would be transported offsite by licensed contractors to existing, 

licensed, disposal facilities operating in compliance with all applicable Federal, State, and local 

requirements, and all nonradioactive, liquid discharges would be discharged in compliance with 

the provisions of the applicable TPDES permit. For these reasons, these impacts are not 

discussed separately in the evaluation of each alternative site. 

The impacts described in Chapter 6 (e.g., nuclear fuel cycle, decommissioning) would not vary 

significantly from one site to another. This is true because all of the alternative sites and the 

proposed site are in low-population areas and because the review team assumes the same 

reactor design (therefore, the same fuel cycle technology, transportation methods, and 

decommissioning methods) for all of the sites. As such, these impacts would not differentiate 

between the sites and would not be useful in the determination of whether an alternative site is 

environmentally preferable to the proposed site. For this reason, these impacts are not 

discussed in the evaluation of the alternative sites. 

The cumulative impacts are summarized for each resource area at each site in the sections that 

follow. The level of detail is commensurate with the significance of the impact for each resource 

area. The findings for each resource area at each alternative site then are compared in 

Table 9-20 to the cumulative impacts at the proposed site (brought forward from Chapter 7). 
Environmental Impacts of Alternatives 

February 2011 9-45 NUREG-1937 

The results of this comparison are used to determine if any of the alternative sites are 

environmentally preferable to the proposed site. 

9.3.2 Red 2 

This section covers the review team’s evaluation of the potential environmental impacts of siting 

a new two-unit nuclear power plant at the Red 2 site in northeastern Texas near the Oklahoma 

border. The site is located in a rural area of Fannin County 3.7 mi north of Savoy and 12.2 mi 

southeast of Denison, on the north side of Valley Lake. The Red River, located 3.7 mi to the 

north of the site, would be the source for water for plant cooling and other plant uses, and 

construction of a new water storage reservoir would be required. Red 2 is a greenfield site not 

currently owned by the applicant (STPNOC 2010a). 

The following sections include a cumulative impact assessment conducted for each major 

resource area. The specific resources and components that could be affected by the 

incremental effects of the proposed action if implemented at the Red 2 site and other actions in 

the same geographic area were considered. This assessment includes the impacts of NRCauthorized construction and operations and impacts of preconstruction activities. Also included 

in the assessment are past, present and reasonably foreseeable future Federal, non-Federal, 

and private actions that could have meaningful cumulative impacts when considered together 

with the proposed action if implemented at the Red 2 site. Other actions and projects 

considered in this cumulative analysis are described in Table 9-8. 

The STP site is more than 300 mi from the Red 2 site and was therefore not included in this 

analysis. The only other nuclear power plant currently operating in Texas is Comanche Peak. 

The Comanche Peak plant is more than 120 mi from the Red 2 site and therefore is also not 

included in the cumulative impact analysis. The proposed nuclear power plant in Victoria 

County is approximately the same distance as the STP site and was not included in the 

cumulative impact analysis. 
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NUREG-1937 9-46 February 2011 

Table 9-8. Past, Present, and Reasonably Foreseeable Future Projects and Other Actions 

Considered in the Cumulative Analysis of the Red 2 Alternative Site 

Project Name Summary of Project 

Location 

(relative to Red 2 site) Status 

Energy Projects 

Valley Power Plant Three gas-fired generation 

units with total installed 

capacity of 1115 MW 

About 1.8 mi south of 

Red 2 site 

Mothballed. Owner 

ceased operations 

on September 30, 

2010(a). The plant 

was previously shut 

down in 2004-2005 

and was 

subsequently 

restarted in 2006 to 

meet demand. Plant 

is available for 

restart depending on 

regional demand (b). 

Pattillo Branch 

Power Plant 

Four new gas-fired turbines 

with total installed capacity of 

1400 MW 

Approximately 3 mi 

south of Red 2 site 

Proposed. Air 

Permit issued 

June 17, 2009(c)

Mining Projects 

Trinity Materials 

(Hendrix Mine) 

Construction sand & gravel 

mine 

About 12 mi northwest 

of Red 2 site 

Operational(d)

Parks 

Caddo-LBJ National 

Grasslands 

National grasslands managed 

by the U.S. Department of 

Agriculture 

About 14 mi northeast 

of Red 2 site 

Development likely 

limited within this 

area(e)

Other 

Actions/Projects:

 

City of Bells Sewage treatment facility About 3 mi southwest 

of Red 2 site 

Operational(f)

City of Denison – 

Paw Paw 

wastewater 

treatment plant 

Sewage treatment facility About 11 mi northwest 

of Red 2 site 

Operational(g)

Lake Ralph Hall Water storage for municipal use 

and for recreation 

About 30 mi southeast 

of Red 2 site 

Proposed(h)

Lower Bois d'Arc 

Creek Reservoir 

Water storage for municipal use 

and for recreation 

About 20 mi east of 

Red 2 site 

Proposed. 

Construction is 

planned to begin in 

2015 and take three 

years to complete(i)
Environmental Impacts of Alternatives 

February 2011 9-47 NUREG-1937 

Table 9-8. (contd) 

Project Name Summary of Project 

Location 

(relative to Red 2 site) Status 

Future 

Urbanization 

Construction of housing units 

and associated commercial 

buildings; roads (such as the 

expansion of I-75), bridges, and 

rail; construction of waterand/or wastewater- treatment 

and distribution facilities and 

associated pipelines, as 

described in local land-use 

planning documents. 

Throughout region Construction would 

occur in the future, 

as described in state 

and local land-use 

planning documents 

Various hospitals 

and industrial 

facilities that use 

radioactive 

materials 

Medical and other isotopes Within 50 mi Operational in 

nearby cities and 

towns 

(a) Source: ERCOT 2010 

(b) Source: North Texas eNews 2010a 

(c) Source: TCEQ 2009e 

(d) Source: EPA 2009i 

(e) Source: USFS 2009 

(f) Source: EPA 2009j 

(g) Source: EPA 2009k 

(h) Source: UTRWD 2010 

(i) Source: NTMWD 2009

9.3.2.1 Land Use 

The following impact analysis includes impacts from building activities and operations. The 

analysis also considers other past, present, and reasonably foreseeable future actions that 

impact land use, including other Federal and non-Federal projects listed in. For this analysis, 

the geographic area of interest for considering cumulative impacts is the 15-mi region 

surrounding the Red 2 site. This geographic area of interest was selected to include the primary 

communities (e.g., Denison) that would be affected by the proposed project if it were located at 

the Red 2 site. Figure 9-5 shows the location of the Red 2 site and surrounding communities. 

The Red 2 site is located in a rural, mostly cleared agricultural area. There is no current zoning 

applicable to the site. There are several residences in the area and a school is located in 

Savoy. STPNOC estimates that approximately 47 percent of the site is forested, 51 percent is 

in cropland, and 2 percent is water resources (STPNOC 2010a). A rail spur is approximately 

4 mi from the site (STPNOC 2010a). The Red 2 site is not owned by the applicants and 

acquisition of the site for a new power plant would involve land purchase from more than one 

landowner. 
Environmental Impacts of Alternatives 

NUREG-1937 9-48 February 2011 

Figure 9-5. Red 2 Alternative Site and 10-mi Radius
Environmental Impacts of Alternatives 

February 2011 9-49 NUREG-1937 

The Red 2 site is not in the geographic area covered by the Texas Coastal Management 

Program (TCMP 2009); therefore, the Coastal Zone Management Act (CZMA) (16 USC 1451) 

does not apply to this site. 

The Red 2 site is located 1.8 mi north of the Valley Power Plant owned by Luminant Power 

(STPNOC 2010a). The Valley Power Plant is a three-unit, 1115-MW, natural gas-fired plant 

(Luminant 2009). Cooling water for Valley Power Plant comes from Valley Lake. Valley Lake 

has a surface area of approximately 1180 ac and is on Brushy Creek, a tributary to the Red 

River. Construction of Valley Dam, which formed Valley Lake, was completed in 1961 (TSHA 

2009a). The Red 2 site is on the north side of Valley Lake. 

If new nuclear generating units were built at the Red 2 site, the review team assumes that an 

onsite water storage reservoir for plant cooling would be built. Water would be diverted from the 

Red River. The land area affected by building two nuclear generating units at the Red 2 site 

would be approximately 800 ac for the main power plant site and up to 1700 ac for a new 

reservoir (STPNOC 2010a). Land-use impacts would also occur as a result of pipeline building 

to divert water to the plant and/or a reservoir and return discharge water to the Red River andfor 

road and rail access. Most land-use impacts would occur during building, while plant operations 

would have minimal land-use impacts. The land-use impacts associated with building the plant 

and the reservoir at the Red 2 site would be noticeable, but not destabilizing. 

There are no existing transmission corridors connecting directly to the Red 2 site. However, 

there are multiple 345-kV transmission lines connecting to the Valley Power Plant (STPNOC 

2010a). One or more new transmission corridors would need to be created to connect the 

Red 2 site to these lines. The corridor(s) would pass through areas that are mostly rural with 

low population densities. Farmlands that would become part of a corridor could generally 

continue to be farmed. The land-use impacts of building one or more transmission corridors to 

serve the Red 2 site would be minimal. 

Within the 15-mi geographic area of interest, the reasonably foreseeable future project with the 

greatest potential to affect cumulative land use would be the Pattillo Branch Power Plant (see 

Table 9-8). If constructed, the Plant would be located approximately 3 mi south of the Red 2 

site. If the Pattillo Branch Power Plant is constructed, one or more new transmission corridors 

would be needed to connect the plant to the grid. 

Future urbanization, the continued operation of the Trinity Materials Hendrix Mine, and global 

climate change (GCC) (see Table 9-8) could contribute to decreases in open lands, wetlands, 

and forested areas. Urbanization in the vicinity of the Red 2 site would alter important attributes 

of land use. Urbanization would reduce natural vegetation and open space, resulting in an 

overall decline in the extent and connectivity of wetlands, forests, and wildlife habitat. Continued 

operation of the Trinity Materials Hendrix Mine could include expansion of the mine at some point 

in the future. Potential expansion of the mine would result in a loss of open lands, forests, and 
Environmental Impacts of Alternatives 

NUREG-1937 9-50 February 2011 

wetlands. GCC could decrease precipitation causing more frequent droughts when combined 

with increased evaporation in the geographic area of interest for the Red 2 site (GCRP 2009). 

Therefore, a reduced water supply combined with increased temperatures could reduce crop 

yields and livestock productivity (GCRP 2009), which might change portions of agricultural and 

ranching land uses in the area of interest. However, existing parks, reserves, and managed 

areas would help preserve open lands, wetlands, and forested areas, to the extent that they are 

not adversely affected by more droughts. Future urbanization trends and direct changes 

resulting from GCC could noticeably alter land uses in the geographic area of interest. 

Based on the information provided by STPNOC and the review team’s independent review, the 

review team concludes that the cumulative land-use impacts of constructing and operating two 

new nuclear generating units at the Red 2 site would be MODERATE. This conclusion reflects 

the substantial amount of land (up to 2500 ac onsite and additional offsite land for roads, a 

railroad spur, and pipelines) that would be needed for the project, the land-use impacts 

associated with the proposed Pattillo Branch Power Plant, and the land needed to connect new 

units at the Red 2 site and the Pattillo Branch Power Plant to the electrical grid, and land use 

changes from increased urbanization and GCC. Building and operating two new nuclear units 

at the Red 2 site would be a significant contributor to the MODERATE impact. 

9.3.2.2 Water Use and Quality 

The following impact analysis includes impacts from building activities and operations. The 

analysis also considers other past, present, and reasonably foreseeable future actions that 

impact water use and quality, including other Federal and non-Federal projects listed in 

Table 9-8. Geographic areas of interest are (1) for surface water the drainage basin of the Red 

River upstream and downstream of the site, and (2) for groundwater the aquifers upgradient and 

downgradient of the site. These regions are of interest because they represent the water 

resource potentially affected by the proposed project if it were located at the Red 2 site. 

The Red 2 site is located in Fannin County in northeastern Texas near the Oklahoma border, 

3.7 mi south of the Red River. The Red 2 site is on the north side of Valley Lake; however, the 

water of Valley Lake is not available for use. To support operation of the proposed units if they 

were to be placed at the Red 2 site, a new water storage reservoir on the site would be required. 

As stated in Section 2.3.2, water use in Texas is regulated by the Texas Water Code. As 

established by Texas Water Code, surface water belongs to the State of Texas (Texas Water 

Code, Chapter 11, Section 11.021). The right to use surface waters of the State of Texas may 

be acquired in accordance with the provisions of the Texas Water Code, Chapter 11. In Texas, 

surface water is a commodity. Since the Red River Basin is currently heavily appropriated, 

future water users in this basin would likely only obtain surface water by purchasing or leasing 

existing appropriations. Regarding groundwater, Texas law has allowed landowners to pump 

the water beneath their property without consideration of impacts to adjacent property owners 

(NRC 2009). However, Chapter 36 of Texas Water Code authorized groundwater conservation 
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February 2011 9-51 NUREG-1937 

districts to help conserve groundwater supplies and issue groundwater permits. Chapter 36, 

Section 36.002, Ownership of Groundwater, states that ownership rights are recognized and 

that nothing in the code shall deprive or divest the landowners of their groundwater ownership 

rights, except as those rights may be limited or altered by rules promulgated by a district. Thus, 

groundwater conservation districts with their local constituency offer groundwater management 

options (NRC 2009). Existing projects in the State have appropriations to use water for their 

requirements. The review team expects that future projects, including the proposed units, if 

they were to be built and operated at the Red 2 site, would operate within the limits of these 

existing surface water and groundwater appropriations. 

As stated in Section 7.2.1, the U.S. Global Change Research Program (GCRP), a Federal 

Advisory Committee, has compiled the state of knowledge in climate change. This compilation 

has been considered in the preparation of this EIS. The projections for changes in temperature, 

precipitation, droughts, and increasing reliance on aquifers within the Red River Basin are 

similar to those in the Colorado River Basin (GCRP 2009). Such changes in climate would 

result in adaptations to both surface water and groundwater management practices and policies 

that are unknown at this time. 

There are currently 249 water rights owners in the Red River Basin, with total water rights of 

456,000 ac-ft/yr that are categorized as industrial, irrigation, or mining users (TCEQ 2009a). 

According to the TCEQ’s water availability maps, unappropriated flows in the Red River Basin 

for a perpetual water rights permit are available 0 to 25 percent of the time (TCEQ 2009b). The 

water availability maps do not show the quantity of available water for a new appropriation 

(TCEQ 2009b). 

The average groundwater use in Fannin County from 1980-1999 is approximately 3168 ac-ft/yr 

and the predicted future groundwater use during 2000-2025 is approximately 2622 ac-ft/yr 

(R.W. Harden and Associates, Inc. 2007). Large water level declines in the Woodbine Aquifer 

due to heavy pumping in the past have resulted in suppliers switching to surface water and 

decreased future demand (TWDB 2006a). The estimated managed available groundwater(a) for 

the Woodbine Aquifer in the Fannin County is 2676 ac-ft/yr (Wade 2008). 

Building Impacts

The review team assumed that no surface water would be used to build the proposed units at 

the Red 2 site so there would be no impact on surface water use. This assumption is consistent 

with the analysis done for the STP site and the other alternative sites. 

 

(a) Managed available groundwater is the volume of groundwater available for permitting and withdrawal 

that would support the desired future conditions established by a groundwater management authority 

(GMA). 
Environmental Impacts of Alternatives 

NUREG-1937 9-52 February 2011 

The impacts on surface water quality from building potential units at the Red 2 alternative site 

would be limited to stormwater runoff that may enter nearby streams and rivers. Additionally, 

treated sanitary wastewater may be discharged to these streams and rivers. Building impacts 

would be limited by the duration of these activities, and therefore, would be temporary. The 

State of Texas prohibits the unauthorized discharge of waste into or adjacent to water in the 

state (Texas Water Code, Chapter 26, Section 26.121). The discharge of waste may be 

authorized under a general or individual permit (Texas Water Code, Chapter 26). These 

permits may require a stormwater pollution prevention plan (SWPPP) that includes BMPs 

appropriate for the site (TCEQ 2003; STPNOC 2010a). Implementation of BMPs should 

minimize impacts to wetlands and surface-water bodies near the Red 2 alternative site. 

Therefore, the water quality impacts on wetlands and water bodies near the Red 2 alternative 

site related to building the proposed units would be temporary and minimal. 

The review team assumes that the groundwater use for building activities at the Red 2 site 

would be identical to the proposed groundwater use for the STP site (STPNOC 2009a) because 

the site would utilize units similar to those proposed for the STP site and the building activities 

would also be similar. Monthly normalized groundwater use for the STP site ranges up to 

491 gpm (792 ac-ft/yr) (Table 3-4 in Chapter 3). STPNOC stated that groundwater would be 

used for potable and sanitary use, concrete batch plant operation, concrete curing, dust 

suppression and cleaning, placement of engineered backfill, and piping hydrotests and flushing 

(STPNOC 2010a). 

The Red 2 alternative site is located in the Texas Groundwater Management Area (GMA) 8 and 

the Red River Groundwater Conservation District (RRGCD). The RRGCD started its operations 

on September 1, 2009. As of November 2010, the RRGCD has not published any rules or 

permitting requirements for groundwater use in the district. GMA 8, however, has established a 

desired future condition(a) for average drawdown in Fannin County to not exceed 186 ft from the 

estimated groundwater elevations in 2000 after 50 years of use (TWDB 2009). 

If the estimated groundwater demand during building of the proposed units at the Red 2 

alternative site were to be obtained using a new groundwater permit, this groundwater use 

would constitute approximately 30 percent of the managed available groundwater from the 

Woodbine Aquifer in Fannin County. However, STPNOC stated (STPNOC 2009a) that 

groundwater from the Trinity Aquifer is also available, that access to groundwater production 

from existing wells would be sought before requesting new or future groundwater capacity, and 

that water could be imported primarily for potable uses and thereby reduce groundwater 

demand. 

 

(a) A desired future condition is a metric that specifies the future value of the related aquifer 

characteristic such as groundwater elevation, groundwater quality, spring flow, and others that may 

be deemed suitable by a GMA. 
Environmental Impacts of Alternatives 

February 2011 9-53 NUREG-1937 

Since the duration of building activities is approximately five years, the review team considers 

these impacts to be temporary. A potential plant at the Red 2 alternative site could use a large 

fraction of the available groundwater resource during that period. Assuming a new groundwater 

permit were issued and based on the magnitude of this use and the potential for substantial 

drawdown, the review team concludes that the impact on the groundwater resource associated 

with the building of the facilities at the Red 2 alternative site would be noticeable but temporary 

and not sufficient to destabilize the groundwater resource. 

During the building of a potential plant at the Red 2 alternative site, impacts to groundwater 

quality may occur from leaching of spilled effluents into the subsurface and intrusion of lowerquality water of the Red River into the Woodbine Aquifer. STPNOC stated that BMPs would be 

in place during building activities (STPNOC 2010a). Therefore the review team concludes that 

any spills would be quickly detected and remediated. The amount of drawdown in the 

Woodbine Aquifer from groundwater pumping during building should support established 

desired future conditions. The drawdown could be limited by installing multiple, appropriatelyspaced wells. The review team concluded that the drawdown in the Woodbine Aquifer could be 

managed during building-related groundwater pumping using an appropriately designed well 

system. In addition, building impacts will be limited by the duration of these activities and, 

therefore, would be temporary. Because any spills would be quickly remediated using BMPs, 

the activities would be temporary, and drawdown in the Woodbine Aquifer would be controlled, 

the review team concludes that the groundwater-quality impacts from building at the Red 2 site 

would be minimal. 

Operational Impacts

STPNOC estimated that a two-unit plant operated at the Red 2 alternative site using a closedcycle cooling system that would employ a cooling water reservoir would consume a maximum of 

50,000 ac-ft of water per year. The Red River would be the source of cooling water at the Red 

2 alternative site. STPNOC currently does not own the necessary water rights. STPNOC would 

need to acquire existing Texas Red River water rights that are currently being used for 

industrial, irrigation, and mining use. Therefore, STPNOC would need to acquire a minimum of 

11 percent of these Texas water rights. 

According to TCEQ, acquired water rights would have to be aggregated at a single point of 

diversion which may lead to concerns regarding instream flow to maintain water quality and 

habitat. The TCEQ staff stated that, under current Texas laws, the acquisition and aggregation 

process would need to consider the quantity and location of all water rights and the instream 

flow needs that may be affected by transfer of these water rights (NRC 2009). Additionally, the 

waters of the Red River are shared by Texas, Oklahoma, Arkansas, and Louisiana under the 

Red River Compact (TCEQ 2009c). Because STPNOC has not identified the particular water 

rights that may be acquired, it is difficult to determine if any are suitable for acquisition. 

However, the review team expects that the TCEQ permitting process would require STPNOC to 
Environmental Impacts of Alternatives 

NUREG-1937 9-54 February 2011 

acquire water rights in sufficient quantity, at appropriate locations, and of appropriate type within 

the Red River Basin such that this reallocation of water rights would not adversely affect surface 

water use and quality in the basin. As such, based on the water rights that would need to be 

reallocated to accommodate the facility at the Red 2 site, the review team determines that the 

operational surface water use impact of potential units at the Red 2 alternative sites would be 

noticeable but not destabilizing. 

During the operation of a potential plant at the Red 2 alternative site, impacts to surface water 

quality could result from stormwater runoff, discharges of treated sanitary and other wastewater, 

blowdown from service water cooling towers, and periodic discharges from the cooling water 

reservoir into the receiving water body. As mentioned above, the State of Texas may require 

STPNOC to obtain a general or individual permit for the discharge of stormwater (Texas Water 

Code, Chapter 26). These permits may require an SWPPP that includes BMPs appropriate for 

the site (TCEQ 2001; STPNOC 2010a). Any discharges of sanitary and other wastewaters and 

blowdown or cooling water reservoir discharges would be controlled by the State of Texas under 

a TPDES permit. The State of Texas limits the quantity and quality of discharges to surface 

water bodies while accounting for concurrent streamflow and quality conditions within the 

surface water body. These permit conditions would also account for designated uses of the 

receiving surface water body. The review team expects that the conditions placed on 

operations of the proposed units at the Red 2 site would be similar to those currently placed on 

the existing facilities at the STP site (Section 5.2.3.1). Therefore, the review team concluded 

that the operational impact on surface water quality of the receiving water body would be 

minimal because the discharge quantity and quality would be controlled. 

The proposed Units 3 and 4 would use approximately 975 gpm (1572 ac-ft/yr) of groundwater 

during normal operations and approximately 3434 gpm (5538 ac-ft/yr) during maximum demand 

conditions (STPNOC 2010a). STPNOC stated that the expected groundwater use for Units 3 

and 4 are assumed to also apply to alternative sites (STPNOC 2009a). However, for maximum 

operation demand periods, STPNOC assumes that a temporary increase in the rate of surface 

water use would be available (STPNOC 2009a). 

The review team determined that the groundwater use at the Red 2 alternative site during 

operations would not be unreasonable because the alternate site would utilize units similar to 

those proposed for the STP site. 
Environmental Impacts of Alternatives 

February 2011 9-55 NUREG-1937 

As discussed, the managed available groundwater in Fannin County from the Woodbine Aquifer 

is 2676 ac-ft/yr. STPNOC estimated normal operational groundwater demand for the two units, 

if they were to be operated at the Red 2 alternative site and used a new groundwater permit, 

would constitute approximately 59 percent of the managed available groundwater of the 

Woodbine Aquifer in Fannin County. However, STPNOC stated (STPNOC 2009a) that 

groundwater from the Trinity Aquifer is also available, that access to existing groundwater 

production from current wells would be sought before requesting new or future groundwater 

capacity, and that water could be imported primarily for potable uses and thereby reduce 

groundwater demand. The review team concludes that a potential plant at the Red 2 site could 

use a large fraction of the managed available groundwater resource during operations. 

If a new groundwater permit were issued, this level of groundwater use and the potential for 

substantial drawdown of the Woodbine Aquifer to occur over the operational period of the facility 

causes the review team to conclude that the impact of operational groundwater use at the Red 2 

site would be noticeable. However, based on available information on the aquifer, and the 

authority of groundwater conservation districts to manage and permit groundwater resources 

(Texas Water Code, Chapter 36), the impact to the groundwater resource under a groundwater 

use permit issued by the applicable groundwater conservation district would not destabilize the 

groundwater resource. 

During operation of a potential plant at the Red 2 alternative site, impacts to groundwater quality 

result from intrusion of lower-quality water of the Red River into the Woodbine Aquifer or from 

the requirement to draw groundwater from deeper strata of the Woodbine Aquifer. Groundwater 

quality declines with depth in the Woodbine Aquifer. The amount of drawdown in the Woodbine 

Aquifer from groundwater pumping during operation should support the established desired 

future conditions. Based on standard geohydrologic practice, the review team determined that 

the drawdown could be limited by installing multiple, appropriately-spaced wells. The Red 2 site 

is located more than 3 mi away from the Red River, and therefore, the review team assumes 

wells would be located away from the river. The review team concludes that the drawdown in 

the Woodbine Aquifer could be managed during operation-related groundwater pumping using 

an appropriately designed well system; however, substantial drawdown would likely occur 

locally to the well field. The review team concludes that the impacts to groundwater quality local 

to the well field could range from minimal to noticeable, but would not be sufficient to destabilize 

the groundwater resource assuming the desired future condition of the aquifer is not violated. 

During operation of any potential plant at the Red 2 alternative site, impacts to groundwater 

quality may occur from leaching of spilled effluents into the subsurface or intentional discharge 

of effluents to groundwater. However, spills that might affect the quality of groundwater would 

be prevented or detected and mitigated by BMPs and no intentional discharge of effluents to 

groundwater should occur. Because any spills would be quickly detected and remediated 

through the use of BMPs, and there should be no intentional discharges to groundwater, and 
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NUREG-1937 9-56 February 2011 

because the drawdown in the Woodbine Aquifer would be controlled but perhaps result in 

noticeable changes in groundwater quality, the review team concludes that the 

groundwater-quality impacts from operation at the Red 2 site would be minimal to noticeable but 

not destabilizing. 

Cumulative Impacts

In addition to water use and water quality impacts from building and operations activities, 

cumulative analysis considers past, present, and reasonably foreseeable future actions that 

impact the same environmental resources. For the cumulative analysis of impacts on surface 

water, the geographic area of interest for the Red 2 site is considered to be the drainage basin 

of the Red River upstream and downstream of the site because this is the resource that would 

be affected by the proposed project. Key actions that have past, present, and future potential 

impacts to water supply and water quality in the Red River basin include the existing Valley 

Power Plant, Trinity Materials Hendrix Mine, and sewage treatment facilities. Key actions that 

could have future potential impacts to water supply and water quality include the planned 

Pattillo Branch Power Plant, and the Lower Bois d’Arc Creek Reservoir. The Pattillo Branch 

Power Plant is to be located approximately 1 mi south of the existing Valley Lake. The 

project would host four natural-gas powered units, with a combined output of approximately 

1400 MW. 

Cumulative Water Use

The only surface-water-use impacts of building and operating a nuclear power plant at the 

Red 2 site are the demands occurring during operation. The projected consumptive surface 

water use of the two units is expected to be about 50,000 ac-ft/yr and would require at least 

11 percent of the current held water rights of 456,000 ac-ft/yr in the Red River Basin, which 

would be a significant fraction of the existing water rights. Past and present water withdrawals, 

reflected by the water rights held in the Red River Basin, have used the waters of the river. 

Currently, unappropriated flows in the Red River Basin are available for a perpetual water rights 

permit only one-quarter of the months during a typical year. 

Increases in consumptive use of water in the Red River drainage is anticipated in the future 

primarily due to population growth (TWDB 2006b). Because the total rated power output of the 

Pattillo Branch Power Plant is smaller than that of the two proposed units, the increase in the 

region’s consumptive water use from the Pattillo Branch Power Plant is likely to be smaller than 

the consumptive use of the two proposed units, if they were to be located at the Red 2 site. The 

region’s water management strategy includes conservation, reuse, and development of new 

water supplies, including building the Bois d’Arc reservoir, that would meet and exceed the 

region’s 2060 water needs if all strategies are implemented (TWDB 2006b). The impacts of the 
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February 2011 9-57 NUREG-1937 

Pattillo Branch Power Plant on the region’s water use would be noticeable but not destabilizing. 

The impacts of the other projects listed in Table 9-8 would have little to no impact on surface 

water use. 

Groundwater-use impacts of building and operating a nuclear power plant at this site are 

characterized by the groundwater demand at the STP site, and those use levels are 491 gpm 

(792 ac-ft/yr) during building, a normal operation demand of 975 gpm, and a maximum 

operation demand of 3434 gpm (STPNOC 2010a). However, for maximum operation demand 

periods, STPNOC assumes that a temporary increase in the rate of surface water use would be 

available for the short duration event. During building and normal operation STPNOC would 

rely on a balance of (1) a new groundwater permit and associated wells in the Woodbine and 

Trinity Aquifers, (2) access to existing groundwater production from wells in the vicinity of the 

plant completed in either the Woodbine or Trinity Aquifers, and (3) use of imported water 

primarily for potable use onsite that would reduce groundwater demand (STPNOC 2009a). With 

regard to the groundwater resource available to all past, present, and future projects, the 

managed available groundwater for the Woodbine Aquifer in Fannin County is 2676 ac-ft/yr, and 

the predicted future groundwater use through 2025 is 2622 ac-ft/yr. Based on this quantification 

of the groundwater resource within Fannin County, the review team concludes that past and 

present projects have fully utilized the Woodbine Aquifer resource. 

As indicated above, groundwater would be used during the building and operation of two 

nuclear units at the Red 2 site. The possibilities exist that STPNOC could (1) use available 

groundwater from both the Woodbine and Trinity Aquifers, (2) acquire groundwater sufficient to 

build and operate Red 2 units from existing permitted groundwater wells, and (3) import water 

for primarily potable water supplies and thereby reduce groundwater demand (STPNOC 2009a). 

Assuming that these strategies are implemented, some but not a substantial impact is 

anticipated to other nearby users of groundwater. However, if only new permits are issued to 

provide the needed groundwater and new wells are drilled to provide the groundwater, then the 

review team expects impacts to nearby users of groundwater would be controlled and limited 

through the permitting process and rules of the groundwater conservation district. As such, 

impacts to groundwater use would be minimal. 

The review team is also aware of the potential for GCC affecting the water resources available 

for closed-cycle cooling and the impact of reactor operations on water resources for other users. 

The impact of GCC on regional water resources is not precisely known, however it may result in 

decreases in precipitation and increases in average temperature (GCRP 2009). Such changes 

could further stress regional water resources. However, the impacts related to GCC would be 

similar for all the alternative sites. 

Historically, the waters of the Red River Basin have been used extensively. The region has a 

planning, allocation, and development system in place to manage the use of its limited surface 

water supplies (TWDB 2006a, b). As stated above, operation of the proposed units on the 
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NUREG-1937 9-58 February 2011 

Red 2 site would result in a noticeable but not destabilizing impact to the surface water use in 

the region. Future projects in the region would also result in noticeable but not destabilizing 

impacts on surface water use in the region. Therefore, the review team concludes that 

cumulative impacts to surface water use would be MODERATE. Building and operating the 

proposed plant at the Red 2 site would be a significant contributor to surface-water-use impacts 

because of the impacts arising from the acquisition and especially the aggregation of surfacewater rights necessary to supply the plant. The review team concludes that cumulative impacts 

to groundwater use would be MODERATE. Building and operating the proposed plant at the 

Red 2 site would be a significant contributor to this groundwater-use impact because the implied 

use of groundwater would exceed the current estimate of managed available groundwater 

resource by approximately 30 percent for building and 59 percent for operating the plant. 

Cumulative Water Quality

Point and nonpoint sources in the river basin have affected the water quality of the Red River. 

Water quality information presented above for the impacts of building and operating the new 

units at the Red 2 site would also apply to evaluation of cumulative impacts. The State of Texas 

may require an applicant to obtain a general or individual permit for discharge of stormwater 

(Texas Water Code, Chapter 26). These permits may require an SWPPP that includes BMPs 

appropriate for the site (TCEQ 2001, 2003; STPNOC 2010a). The State of Texas would also 

issue TPDES permits for the discharge of sanitary and other wastewaters, including blowdown 

from service water cooling towers and cooling water reservoir discharges, before operation of 

the proposed units at the Red 2 site. Effluent discharges through a TPDES-permitted outfall, 

such as those from Valley Power Plant, Trinity Materials Hendrix Mine, and sewage treatment 

plants, are required to comply with the Clean Water Act. Such permits are designed to protect 

water quality. Therefore, the review team concluded that the cumulative impact on surface 

water quality of the receiving water body would be SMALL. The impacts of other projects listed 

in Table 9-8 would have little or no impact on surface water quality. 

The review team also concludes that with the implementation of BMPs, the impacts of 

groundwater quality from building two new nuclear units at the Red 2 site would likely be 

minimal. However, during operation, the production of groundwater from wells under a new 

permit could result in groundwater-quality impacts ranging from minimal to being altered 

noticeably because of the degradation in water quality. The individual impacts from other 

projects listed in Table 9-8 would have little or no impact on regional groundwater quality 

because of the local nature of groundwater withdrawals and their associated impacts. 

Therefore, the cumulative impact on groundwater quality would be SMALL to MODERATE. 

Building and operating the proposed plant at the Red 2 site would be a significant contributor to 

these water quality impacts. 
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February 2011 9-59 NUREG-1937 

9.3.2.3 Terrestrial and Wetland Resources 

The following impact analysis includes impacts from building activities and operations. The 

analysis also considers other past, present, and reasonably foreseeable future actions that 

impact terrestrial and wetland resources, including other Federal and non-Federal projects listed 

in Table 9-8. For the analysis of terrestrial ecological impacts, the geographic area of interest is 

the intersection of the East Texas Plains and Blackland Prairies ecoregion with the Bois d’Arc 

Island watershed in Grayson and Fannin Counties (Figure 9-6). This geographic area of 

interest is expected to encompass the ecologically relevant landscape features and species. 

The Red 2 site is a greenfield site located on the northern edge of Valley Lake in Fannin 

County. The site is in the Blackland Prairies subprovince of the Gulf Coast Plains. The 

blacklands have a gentle undulating surface that has been cleared of most natural vegetation 

for the cultivation of crops (UT 1996). The soils of the blacklands are chalks and marls that 

have weathered to deep, fertile clay soils. Pre-settlement conditions were that of a true prairie 

grassland community dominated by a diverse assortment of perennial and annual grasses and 

forbs, with sparsely scattered trees or mottes of oaks (Quercus sp.) on the uplands (TPWD 

2009a). Forested or wooded areas were restricted to bottomlands along major rivers and 

streams, ravines, protected areas, or on certain soil types. Trees such as pecan 

(Carya illinoinensis), cedar elm (Ulmus crassifolia), cottonwoods (Populus spp.), various oaks, 

and hackberry (Celtis sp.) dotted the landscape (TPWD 2009b). The dominant grass was the 

little bluestem (Schizachyrium scoparium). Other grasses included the big bluestem 

(Andropogon gerardii), Indiangrass (Sorghastrum sp.), eastern gamagrass 

(Tripsacum dactyloides), switchgrass (Panicum virgatum), and sideoats grama 

(Bouteloua curtipendula). 

Currently, the region surrounding the Red 2 site is mostly rural, with much of the prairie 

converted to cropland and non-native pasture. In August 2009, NRC staff visited the site and 

found that the site contained buildings, roads, pastures, and small wooded areas (NRC 2009). 

The total acreage for all temporary and permanent impacts would be approximately 800 ac for 

the plant site and 1700 ac for the reservoir. Permanent impacts associated with building two 

new nuclear units at the Red 2 site would include approximately 150 ac for each unit (300 ac 

total) and a new 1700-ac reservoir for cooling water for the plant (STPNOC 2010a). While 

specific habitat acreages have not been determined for the site, Table 9-9 gives approximate 

acreages by land cover class for areas experiencing permanent impacts. No assessment was 

made for land cover classes receiving temporary impacts. The acreages for land cover classes 

receiving permanent impacts are from the ER and were based on evaluation of Google Earth 

Imagery (STPNOC 2010a). 
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NUREG-1937 9-60 February 2011 

Figure 9-6. Geographic Area of Analysis of Cumulative Impacts to Terrestrial Resources for 

the Red 2 Site in Grayson and Fannin Counties 

 
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February 2011 9-61 NUREG-1937 

Table 9-9. Estimated Land Cover Classes for Approximately 2000 ac of the 2500 ac Red 2 

Site. 

Land Cover Class Plant (ac) Reservoir (ac) 

Forested 80 850 

Cleared farmland 220 800 

Water resources/freshwater ponds (no 

high quality forested wetlands identified) 

0 50 

Source: STPNOC 2010a 

Water features at the Red 2 site include a portion of Valley Lake, estimated to be 100 ac, 

located in the extreme southwestern portion of the site. Numerous freshwater ponds are also 

scattered throughout the site with an estimated total acreage of 50 ac. In addition, there are a 

few freshwater, emergent wetland areas totaling less than 1 ac. No high quality forested 

wetlands have been identified in the immediate site area (STPNOC 2010a). 

Ecologically important areas occurring near the Red 2 site include the Caddo-LBJ National 

Grasslands approximately 15 mi from the site; the grasslands cover more than 16,000 ac 

(TPWD 2009c). TPWD (2009d) has indicated there is potential for native pasture or native 

prairie remnants in Fannin County. Additionally, two Ecologically Significant River and Stream 

Segments occur in Fannin County associated with Bois d’Arc Creek and Coffee Mill Creek 

(TPWD 2010). Portions of the Bois d’Arc Creek include Priority 4 Bottomland Hardwood areas 

(STPNOC 2010a). The nearby Hagerman National Wildlife Refuge is home to thousands of 

geese and waterfowl during the winter (STPNOC 2009a). 

Important Species 

A range of wildlife species potentially occur at the Red 2 site (STPNOC 2009a), including the 

following recreationally valuable species: the eastern turkey (Meleagris gallopavo sylvestris), 

mourning dove (Zenaida macroura), white-tailed deer (Odocoileus virginianus), northern 

bobwhite quail (Colinus virginianus), and eastern fox squirrel (Sciurus niger) (STPNOC 2009a). 

All these species are habitat generalists (NatureServe 2009a). Mourning doves use a variety of 

habitats including croplands and pastures, grasslands, and open hardwood forests. The doves 

are ground, seed feeders. The eastern fox squirrel is the largest tree squirrel in the western 

hemisphere (NatureServe 2009a); it is found in open mixed hardwood forests or mixed pinehardwood associations but is well adapted to disturbed areas. Both the eastern turkey and the 

bobwhite quail share many of the same habitat characteristics and have been in decline in the 

Blackland Prairie areas of Texas (TPWD 2009e). Both species are ground nesters and their 

decline has been linked to a lack of nesting and brood rearing habitat (TPWD 2009e). Turkeys 

require dense and diverse patches of grasses and forb, with some shrubs and an abundance of 

insects (TPWD 2009e). Northern bobwhites build their nests at the bases of native 

bunchgrasses, while brood rearing occurs in areas with enough taller herbaceous cover to 
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NUREG-1937 9-62 February 2011 

provide overhead concealment with bare ground underneath for easy movement (TPWD 

2009e). White-tailed deer occur almost entirely in hardwood woodlands, and forage on a widevariety of plants from grasses and forbs, to fruits and nuts (Davis and Schmidly 1994). 

Up to seven bat species living in eastern Texas, can occur in Fannin County (Davis and 

Schmidly 1994; STPNOC 2009a). Some are mostly year-round residents (i.e., non-migratory), 

such as the big brown bat (Eptesicus fuscus), the eastern pipistrelle (Perimyotis subflavus), and 

evening bat (Nycticeius humeralis). Migratory bats that could occur at the site include the hoary 

bat (Lasiurus cinereus), the silver-haired bat (Lasionycteris noctivagans), the eastern red bat 

(Lasiurus borealis), and the Mexican free-tailed bat (Tadarida brasiliensis). The Mexican freetailed bat can be either migratory or non-migratory depending on where it resides; the migratory 

status of bats occurring in Fannin County is currently unknown (STPNOC 2009a). 

The site lies within the Central Flyway of Texas (STPNOC 2009a) – a major migratory corridor 

for neotropical migrants and other birds. Thousands of migrating birds, especially waterfowl, 

flying south from cooler regions of the North American continent could potentially rest and feed 

in this area. Two areas of potential importance to migratory birds in the vicinity of the Red 2 site 

are the Caddo National Grasslands/Wildlife Management Area, approximately 15 mi from the 

site, and the Hagerman National Wildlife Refuge located more than 15 mi from the site 

(STPNOC 2009a). In addition, portions of Bois D’Arc Creek, east of the Red 2 site, include 

Priority 4 Bottomland Hardwood areas that are considered quality habitat for waterfowl. At the 

site audit in 2009, the potential for colonial breeding bird rookeries along the pipeline route was 

noted (NRC 2009). 

No site specific surveys have been conducted for threatened and endangered species at the 

Red 2 site. The following list for Fannin County (Table 9-10) was compiled from the Texas 

Parks and Wildlife Threatened and Endangered Species by County website (TPWD 2009f) and 

the U.S. Fish and Wildlife Service Ecological Service threatened and endangered species for 

the Southwest region website (FWS 2009a). Three species are listed as Federally-threatened 

or endangered in Fannin County (FWS 2009a), and the State lists an additional nine species as 

endangered or threatened (TPWD 2009f). No critical or sensitive habitats for Federally listed 

species have been identified in the immediate site area (FWS 2009d). 

Alligator snapping turtle

The alligator snapping turtle (Macrochelys temminckii) is a State-listed threatened species 

(TPWD 2009f). It is found in slow-moving, deep water of rivers, sloughs, oxbows, and canals or 

lakes associated with rivers, and also in swamps, ponds near rivers, and shallow creeks that are 

tributary to occupied rivers (NatureServe 2009b). It usually occurs in water with mud bottoms 

and abundant aquatic vegetation; it may migrate several miles along rivers (TPWD 2009g). 

Turtles are rarely found out of the water except when nesting. 
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February 2011 9-63 NUREG-1937 

Table 9-10. Federally and State-listed Threatened and Endangered Species in Fannin County, 

Texas 

Group Common Name Scientific Name 

Federal 

Status 

State 

Status 

Reptiles Alligator snapping turtle Macrochelys temminckii T 

Texas horned lizard Phrynosoma cornutum T 

Timber/canebrake rattlesnake Crotalus horridus T 

Birds American peregrine falcon Falco peregrinus anatum T 

 Bald eagle Haliaeetus leucocephalus T 

 Eskimo curlew Numenius borealis E 

 Interior least tern Sternula antillarum athalassos E E 

 Piping plover Charadrius melodus T 

 Whooping crane Grus americana E E 

 Wood stork Mycteria americana T 

Mammals Black bear Ursus americanus T/SA T 

Red wolf Canis rufus E 

Sources: FWS 2009a; TPWD 2009f 

T-threatened; E-endangered; T/SA-proposed similarity of appearance to a threatened taxon 

Texas horned lizard 

The Texas horned lizard (Phrynosoma cornutum) is a State-listed threatened species 

(TPWD 2009f). It can be found in arid and semiarid habitats in open areas with sparse plant 

cover (TPWD 2009g). They dig for hibernation, nesting, and insulation purposes, and are 

commonly associated with loose sand or loamy soils. Populations have declined precipitously 

in eastern Texas, and their decline may be related to the spread of fire ants, use of insecticide 

to control fire ants, heavy agricultural use of the land, and other habitat alterations 

(NatureServe 2009b). Another factor implicated in their decline is over-collecting for the pet and 

curio trade. This species is particularly vulnerable to the loss of harvester ants, which make up 

nearly 70 percent of their diet. 

Timber/canebrake rattlesnake

The timber rattlesnake (Crotalus horridus) is a State-listed threatened species (TPWD 2009f). 

It prefers moist lowland forests and hilly woodlands or thickets near permanent water sources 

such as rivers, lakes, ponds, streams, and swamps (TPWD 2009g). The range of the 

rattlesnake extends from central New England to northern Florida, and west to eastern Texas, 

where its distribution is spotty (NatureServe 2009b). 
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American peregrine falcon 

The American peregrine falcon (Falco peregrinus anatum) is a State-listed threatened species 

(TPWD 2009f). The bird is a year-round resident and local breeder in west Texas where it nests 

in tall cliff eyries (TPWD 2009g). This species also migrates across Texas from breeding areas 

in the United States and Canada to winter along the coast and farther south. The American 

peregrine falcon occupies a wide range of habitats during migration, including urban areas. 

Populations are primarily concentrated along coast and barrier islands. The birds are lowaltitude migrants, with stopovers at leading landscape edges such as lake shores, coastlines, 

and barrier islands. 

Bald eagle 

Although recently delisted from a status of Federally threatened, the bald eagle (Haliaeetus 

leucocephalus) is State-listed as threatened in Texas and will remain Federally protected under 

the Bald and Golden Eagle Protection Act and the Migratory Bird Treaty Act (TPWD 2009f). 

The species will also continue to be protected under the Endangered Species Act (ESA) 

through management guidelines that will be in place for the next five years. Most eagles breed 

in Canada and the northern United States and move south for the winter (NatureServe 2009b). 

Bald eagles can be year-round residents in areas where water bodies do not freeze. Winter 

roost sites can vary with proximity to food resources and eagles commonly roost communally in 

large trees, preferably snags. 

Eskimo curlew

The Eskimo curlew (Numenius borealis) is a State-listed endangered species (TPWD 2009f). 

Eskimo curlews historically migrated from breeding grounds in the Arctic tundra through the 

North American prairies to wintering grounds on the pampas grasslands of Argentina (TPWD 

2009g). Fannin county lies in the historic migration path for this species whose numbers 

currently are estimated to be fewer than 50 (NatureServe 2009b). 

Interior least tern

The interior least tern (Sternula antillarum athalassos) is Federally and State-listed as 

endangered (FWS 2009a; TPWD 2009f). The birds breed along inland river systems including 

the Red River (TPWD 2009g). Interior least terns nest on bare or sparsely vegetated sand, 

shell, and gravel beaches, islands, and salt flats associated with rivers and reservoirs. The 

birds prefer open habitat and avoid thick vegetation and narrow beaches. They arrive at 

breeding areas in early April to early June after wintering along the Central American coast and 

the northern coast of South America. 
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February 2011 9-65 NUREG-1937 

Piping plover

The piping plover (Charadrius melodus) is State-listed as threatened (TPWD 2009f). This 

species is Federally listed as threatened in the State of Texas, but is not listed as occurring in 

Fannin County by FWS (FWS 2009a). Texas is the wintering home for more than 5000 known 

breeding pairs that have migrated from the Great Lakes regions and southern Canada 

(TPWD 2009g). They live on sandy beaches and lakeshores along the Gulf coast and could 

migrate through Fannin County. 

Whooping crane 

The whooping crane is Federally and State-listed as an endangered species (FWS 2009a; 

TPWD 2009f). The FWS does not list this species as occurring in Fannin County, however, it is 

listed by TPWD for the county. Whooping cranes breed in Canada during the summer months 

and migrate to the Aransas National Wildlife Refuge along the Texas coastal plain, staying there 

from November through March (TPWD 2009g). Their winter and migrating habitat includes 

marshes, shallow lakes, lagoons, salt flats, and grain and stubble fields (NatureServe 2009b). 

Migration habitat includes sites with good horizontal visibility, water depth of 30 cm or less, and 

a minimum wetland size of 0.04 ha for roosting. 

Wood stork 

The wood stork (Mycteria americana) is a State-listed threatened species (TPWD 2009f). 

Nesting has been restricted to Florida, Georgia, and South Carolina. However, they may have 

formerly bred in Texas (FWS 2009b), but there are no breeding records since 1960 

(TPWD 2009g). Wood storks forage in prairie ponds, flooded pastures or fields, ditches, and 

other shallow standing water, including saltwater. The birds usually roost communally in tall 

snags, sometimes in association with other wading birds (i.e., active rookeries). A distinct, nonlisted population of wood storks breed in Mexico and then move into Gulf states in search of 

mud flats and other wetlands, even those associated with forested areas. 

Black bear

The black bear (Ursus americanus) is on the State endangered species list (TPWD 2009f) due 

to its similarity to the Louisiana black bear (subspecies U. americanus luteolus). The Louisiana 

black bear is Federally listed as threatened (FWS 2009a); it is not known to be found in Texas, 

although potential habitat exists in the eastern part of the state including Fannin County. 

Habitat for the black bear includes bottomland hardwoods and large tracts of inaccessible 

forested areas (TPWD 2009g). 
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Red wolf

The red wolf (Canis rufus) is State-listed as endangered (TPWD 2009f). Red wolves inhabited 

brush and forested areas, as well as the coastal prairies (Davis and Schmidly 1994). They 

formerly ranged throughout eastern Texas, but appear to now be extinct. 

Building Impacts 

Building impacts would affect up to 2500 ac of land resulting in the permanent loss of 2000 ac of 

terrestrial habitat. Three-hundred ac would be required for permanent structures and facilities, 

and up to 1700 ac would be required for a new reservoir. Of the 300 ac that would be 

permanently affected at the plant site, approximately 220 ac are previously cleared land and 

80 ac are forested. The reservoir would affect approximately 850 ac of forested land, 800 ac of 

previously cleared land, 50 ac of ponds and other water resources, and less than 1 ac of 

emergent wetlands (Table 9-9) (STPNOC 2010a). Only one small freshwater emergent 

wetland (0.9 ac) was identified within the affected area; this wetland occurs in the area identified 

for the main power plant area. (STPNOC 2010a) Additional acreage resulting in permanent 

losses would be associated with transmission corridors, pipelines, roads, and railroad access 

(STPNOC 2010a). 

New transmission lines would be needed to connect the Red 2 site with existing transmission 

lines at the Valley Power Plant, 1.8 mi south. The likely route for new lines would traverse a 

distance of 5 mi and require a 200-ft-wide corridor, which would affect approximately 120 ac of 

land (STPNOC 2010a). The land along the theoretical corridor is a mixture of cleared land and 

forest (STPNOC 2009a). Once at the Valley Power Plant, it is assumed the lines would parallel 

the existing corridor (with potential need for expansion). Erection of the transmission towers 

and stringing of the lines would be expected to comply with all applicable laws, regulations, 

permit requirements, and BMPs (STPNOC 2010a). The building of new transmission line 

corridors would contribute to fragmentation of habitat. 

In addition to the transmission lines, a 3.8-mi-long, 75-ft-wide corridor containing the cooling 

water intake and discharge pipelines between the Red River and new reservoir would be built. 

A 4.2-mi-long, 50-ft-wide rail corridor and a 2.2-mi-long, 75-ft-wide access road would also be 

needed. A total of 81 ac of land would be affected for these new corridors (STPNOC 2010a). 

The land surrounding the site is predominately cropland and non-native pasture and the review 

team assumes a large portion of the acreage needed for the road, pipeline, and rail corridors 

would be previously disturbed. 

No site-specific reports on Federally or State-listed species were available for the Red 2 site. 

As noted above, three Federally listed and nine State-listed species occur in Fannin County and 

may potentially occur at the Red 2 site. 
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February 2011 9-67 NUREG-1937 

Building two new nuclear reactors at the Red 2 site would result in the permanent loss of 

approximately 2000 ac of terrestrial habitat including more than 900 ac of forested habitat and 

minimal loss of wetland habitat. However, the reservoir would provide additional waterfowl 

habitat. Clearing land for the transmission line corridor would increase habitat fragmentation 

along the 5-mi corridor. Other sources of impacts to terrestrial resources such as noise, 

increased risk of collision and electrocution, and displacement of wildlife would likely be 

temporary and result in minimal impacts to the resource. Building the two new units would 

noticeably alter the available terrestrial habitat. 

Operational Impacts 

Impacts on terrestrial ecological resources from operation of two new nuclear units at the Red 2 

site include those associated with transmission system structures, and maintenance of 

transmission line corridors. Also, during plant operation, wildlife would be subjected to impacts 

from increased traffic. An evaluation of specific impacts resulting from building of transmission 

lines and transmission corridor maintenance cannot be conducted in any detail due to the lack 

of information, such as the locations of any new corridors that could result from transmission 

system upgrades. However, in general, impacts associated with transmission line operation 

consist of bird collisions with transmission lines, electromagnetic field (EMF) effects on flora and 

fauna, and habitat loss due to corridor maintenance. 

Direct mortality resulting from birds colliding with tall structures has been observed (Erickson et 

al. 2005). Factors that appear to influence the rate of avian impacts with structures are diverse 

and related to bird behavior, structure attributes, and weather. Migratory flight during darkness 

by flocking birds has contributed to the largest mortality events. Tower height, location, 

configuration, and lighting also appear to play a role in avian mortality. Weather, such as low 

cloud ceilings, advancing fronts, and fog also contribute to this phenomenon. Waterfowl may be 

particularly vulnerable due to low, fast flight and flocking behavior (Brown 1993). Although 

additional transmission lines would be required for two new nuclear units at Red 2, increases in 

bird collisions directly attributable to these lines would be minor and would likely not be 

expected to cause a measurable reduction in local bird populations. 

EMFs are unlike other agents that have an adverse impact (e.g., toxic chemicals and ionizing 

radiation) in that dramatic acute effects cannot be demonstrated and long-term effects, if they 

exist, are subtle (NIEHS 2002). A careful review of biological and physical studies of EMFs did 

not reveal consistent evidence linking harmful effects with field exposures (NIEHS 2002). The 

magnetic fields from many lines, at a distance of 300 ft are similar to typical background levels 

in most homes (NIEHS 2002). Thus, impacts of EMFs on terrestrial flora and fauna are of small 

significance at operating nuclear power plants, including transmission systems with variable 

numbers of power lines (NRC 1996). Since 1997, more than a dozen studies have been 

published that looked at cancer in animals that were exposed to EMFs for all or most of their 
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NUREG-1937 9-68 February 2011 

lives (Moulder 2003). These studies have found no evidence that EMFs cause any specific 

types of cancer in rats or mice (Moulder 2003). 

The impacts associated with corridor maintenance activities are loss of habitat due to cutting 

and herbicide application, and similar impacts where corridors cross floodplains and wetlands. 

The maintenance of transmission-line corridors could be beneficial for some species, including 

those that inhabit early successional habitat or use edge environments. Thus, corridor 

maintenance would not be expected to increase or contribute to cumulative effects. 

The potential effects of operating two new nuclear reactors at the Red 2 site would be primarily 

associated with maintenance of transmission corridors and increased traffic. Operational 

impacts to terrestrial resources would be expected to be minimal. 

Cumulative Impacts 

The impacts of building and operating two units at Red 2 were evaluated by the review team to 

determine the magnitude of their contribution to regional cumulative impacts on terrestrial 

ecological resources. The geographic area of interest for cumulative impacts (Figure 9-6) at 

Red 2 is the intersection of the East Central Texas Plains and Texas Blackland Prairies 

ecoregions and the Bois d’Arc Island watershed in Fannin and Grayson Counties. Activities 

related to building include loss of habitat due to clearing for building of the plant, and filling the 

reservoir. Past actions that have affected terrestrial resources include the construction of the 

Valley Power Plant approximately 2 mi south of the Red 2 site, in which about 300 ac were 

cleared for the plant; and the construction of the Trinity Materials mine approximately 12 mi from 

the Red 2 site (Table 9-8). Both of these actions changed the nature of terrestrial habitat, 

generally through grading, removing and covering the previous terrestrial features. 

Present actions that affect terrestrial resources include construction related to the expansion of 

I-75, 14 mi west of the site (Table 9-8). The project is currently restricted to modifying on and 

off ramps, and disturbs relatively little area; however, future activity could involve expansion of 

the road to 6 lanes. At the Caddo-LBJ National Grasslands, habitat restoration work would 

remove about 200 ac of eastern red cedar (Juniperus virginiana) to allow for restoration of the 

traditional open grassland prairie. 

There are several proposed future actions near the Red 2 site (Table 9-8). The first is the 

proposal to build the Pattillo Branch Power Plant approximately 3 mi south of the Red 2 site. 

This proposed facility would affect approximately 300 ac of terrestrial resources through landclearing and construction activities, plus road and transmission corridors. The second proposal 

is for a reservoir on Bois d’Arc Creek northeast of Bonham Texas, approximately 20 mi east of 

the Red 2 site (Corps 2009). In addition to flooding 17,000 ac, two pipelines would be 

constructed for water delivery; one pipeline would be 29 mi from the reservoir, the other 14 mi 

away. Possible impacts to terrestrial and wetland resources from the power plant and 
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February 2011 9-69 NUREG-1937 

associated transmission line corridors would be habitat loss through removal of habitat 

components (e.g., trees, grassland, access to soil) and habitat fragmentation. The lake would 

inundate the Bois d’Arc Creek bottomland hardwoods area, which is designated as a Priority 4 

habitat (TWDB 2001). The Bois d’Arc reservoir would convert a large terrestrial habitat to an 

aquatic habitat; there would be additional loss of terrestrial habitat through construction of 

pipeline corridors. Also, new transmission lines would add to those associated with the Valley 

Power Plant and the proposed Pattillo Branch Power Plant (Table 9-8). The increase in the 

number of transmission towers would not result in a noticeable increase in bird collisions. The 

proposed Lake Ralph Hall Reservoir (Table 9-8) is outside the geographic area of interest for 

terrestrial impacts at the Red 2 Site. 

The review team is also aware of the potential for GCC affecting the terrestrial resources in the 

geographic area of interest. The future impact of GCC on plant and wildlife species and their 

habitats in the geographic area of interest is not precisely known. GCC effects near the Red 2 

site could result in regional increases in the frequency of severe weather, decreases in annual 

precipitation, and increases in average temperature (GCRP 2009). The decrease in 

precipitation combined with increased temperatures and evaporation could result in more 

frequent droughts. Such changes in climate could alter and fragment terrestrial habitats 

(grasslands and wetlands, including prairie potholes) and could result in shifts in species 

ranges, diversity, and abundance in the geographic area of interest for the Red 2 site 

(GCRP 2009). 

The potential cumulative impact to terrestrial resources within the area of interest given the two 

new reactors at the Red 2 site, the proposed power plant 3 mi south, and the 17,000-ac 

reservoir 20 mi northeast of the site would noticeably alter terrestrial resources. All these 

activities would remove or modify terrestrial habitats with the potential to affect important 

species living or migrating through the area. For the reasons discussed above in Building 

Impacts and Operational Impacts, the incremental contribution of building and operating the two 

new reactors at the Red 2 site to the cumulative impacts within the geographic area of interest 

would be substantial. 

Summary 

Impacts to terrestrial ecology resources and wetland resources were estimated based in the 

information provided by STPNOC and the review team’s own independent review. Two future 

activities in the region that would noticeably affect wildlife and wildlife habitat, in addition to the 

building and operation of two units at the Red 2 site, are the building of the Pattillo Branch 

Power Plant and the Lower Bois d’Arc Creek reservoir (Table 9-8). After building at the Red 2 

site is complete, terrestrial ecological resources in areas that are temporarily disturbed are 

expected to return to predominantly preconstruction conditions. However, the development of a 

1700-ac reservoir would permanently shift resources from terrestrial to aquatic. Additional 

impacts at the reservoir location and plant site would include the potential for affecting more 
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NUREG-1937 9-70 February 2011 

than 900 ac of forested land, and the potential habitat loss for any protected species that could 

occur in the area. While there is uncertainty concerning the possible routing of a new 

transmission corridor, transportation, and pipeline corridors at the Red 2 site, the potential area 

affected is estimated to be relatively small (i.e., about 200 ac). Based on the information 

provided by STPNOC and the review team’s independent evaluation, the review team 

concludes that the cumulative impacts within the area of interest on terrestrial plants and 

animals, including threatened or endangered species, and wildlife habitat in the region would be 

MODERATE. The creation of the Lower Bois d’Arc Creek reservoir is the primary reason for 

this impact level. However, the incremental contribution of building and operating the two new 

reactors at the Red 2 site to the cumulative impacts within the geographic area of interest would 

be significant. 

9.3.2.4 Aquatic Resources 

The following impact analysis includes impacts from building activities and operations. The 

analysis also considers other past, present, and reasonably foreseeable future actions that 

impact aquatic resources, including other Federal and non-Federal projects listed in Table 9-8. 

For the analysis of aquatic ecological impacts at the Red 2 site, the geographic area of interest 

is considered to be all parts of the Red River drainage between the Denison Dam (below Lake 

Texoma Reservoir) and the confluence of the Red River with the Kiamichi River. 

At the Red 2 alternative site, aquatic resources are associated with the Red River, Brushy 

Creek, and the nearby drainages for Pattillo Branch, Sheep Creek, and Bois d’Arc Creek, as 

well as Valley Lake (Figure 9-5). The Red 2 site has been cleared for agriculture, and yet still 

supports numerous springs, intermittent streams, and ponds. The Red River flows through 

Fannin County downstream of Lake Texoma and is the border between Texas and Oklahoma. 

Flows in the Red River are maintained by releases from Lake Texoma Dam. While fishing is 

common in the clear waters of Lake Texoma, recreational fishing is popular in the Red River 

downstream of the dam (McCord 2009). Texas Water Quality Inventory lists chlorophyll-a

concentrations at a level of concern in this portion of the river (TCEQ 2008). The reach of the 

river through Fannin County is not navigable for commercial vessels, but is used for recreational 

boating activities. In addition, there are numerous, intermittent streams and creeks that flow into 

the river (McCord 2009; STPNOC 2010a). 

Valley Lake is a man-made reservoir on Brushy Creek that is owned and operated by Luminant 

Power. The lake’s water is used for condenser cooling and other uses associated with the 

natural gas-fueled, Valley Power Plant (STPNOC 2010a). The lake is popular for recreational 

activities. As stated in Section 9.3.2.2, water from Valley Lake would not be available for 

cooling new nuclear units located at the Red 2 site (STPNOC 2010a). 

Brushy Creek rises east of Valley Lake and flows north for 4 mi through the Red 2 site before 

emptying into the Red River. The creek crosses flat land surfaced by clay and sandy loams with 
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February 2011 9-71 NUREG-1937 

water-tolerant hardwoods, conifers, and grasses along the banks. The review team could not 

find any surveys of aquatic resources in Brushy Creek or the other drainages and ponds in the 

area. Flows in the smaller drainages are assumed to be intermittent and the resources would 

be dependent on seasonal flows. 

Texas Parks and Wildlife Department (TPWD) has designated Bois d’Arc Creek an ecologically 

significant stream segment, from its confluence with the Red River upstream to its headwaters 

in east Grayson County. TPWD notes that the creek has significant habitat value (TPWD 2010). 

Within the Red River drainage up and downstream of the Red 2 site there are a number of past, 

present and potential projects that could affect the aquatic resources (Table 9-8). Past actions 

include building the Valley Power Plant, excavation of the Trinity Materials (Hendrix Mine), and 

the wastewater treatment plants for the cities of Belles and Denison. There are two proposed 

projects in the region that would also affect aquatic resources in vicinity: the gas-powered 

Pattillo Branch Power Plant and the Lower Bois d’Arc Creek Reservoir (16,641 ac). In addition, 

the new nuclear units would require building water intake and discharge systems with 

associated pipelines from the Red River to the new site, inundation of a reservoir, and 

associated transmission corridors to connect with the existing power grid. Without having the 

specific plans for locating all facilities at the Red 2 site, the potential for impacts from building 

and operation of the new units to aquatic biota are likely to be those inhabiting the Red River, 

Valley Lake, Brushy Creek, springs, intermittent streams, ponds, and the nearby drainages for 

Bois d’Arc Creek, Sheep Creek, and Pattillo Branch. 

Non-Native and Nuisance Species 

No non-native or nuisance species have been recorded in the area as a problem. However, 

there are numerous nuisance aquatic species that TPWD considers to be ubiquitous across 

waterways in Texas. These species include: hydrilla (Hydrilla verticillata), water hyacinth 

(Eichhornia crassipes), and giant salvinia (Salvinia molesta). In addition, the Red River basin is 

known to have a number of non-native fish including: common carp (Cyprinus carpio), grass 

carp (Ctenopharyngodon idella), blacktail shiner (Cypinella venusta), bullhead minnow 

(Pimephales vigilax), rudd (Scardinius erythrophthalmus), black buffalo (Ictiobus niger), black 

bullhead (Ameiurus melas), Western starhead topminnow (Fundulus blairae), redspotted sunfish 

(Lepomis miniatus), tadpole madtom (Noturus gyrinus), plains killifish (Fundulus zebrinus), 

yellow perch (Perca flavescens), and walleye (Sander vitreus) (Thomas et al. 2007; HassanWilliams and Bonner 2009; TPWD 2009h). 

Important Species 

The Red River is popular for recreational fishing. The recreational fish species in the Red River 

and in Valley Lake include: alligator gar (Atractosteus spatula), several bass species (spotted 

bass (Micropterus punctulatus), largemouth bass (M. salmoides) and other bass hybrids), 
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NUREG-1937 9-72 February 2011 

bluegill (Lepomis macrochirus), channel catfish (Ictalurus punctatus), and blue catfish 

(I. furcatus), white crappie (Pomoxis annularis), black crappie (P. nigromaculatus), golden 

shiners (Notemigonus crysoleucas), emerald shiners (Notropis atherinoides), and warmouth 

(L. gulosus). In addition, popular introduced sports fish include: striped bass (Morone saxatilis) 

and walleye. Commercial fishing along the reach of the Red River in Fannin County is limited to 

collection of bait fish, e.g., the Mississippi silvery minnow (Hybognathus nuchalis) (Thomas et 

al. 2007; Hassan-Williams and Bonner 2009). The centrachids (largemouth and spotted bass, 

bluegill, crappies, and warmouth) would all be found in lakes, rivers and smaller flowing 

tributaries. The bass and warmouth are top carnivores, whereas the bluegill and crappies are 

insectivores. Alligator gar and catfish are top carnivores and are found primarily in larger 

waterbodies, like rivers and reservoirs. The golden and emerald shiners, cyprinids species, are 

found in lakes, rivers and smaller flowing tributaries, feeding on various aquatic insects. The 

Mississippi silvery minnow would only be found in rivers and smaller tributaries where it 

feeds on soft substrate collecting algae and other organic matter (Thomas et al. 2007; 

Hassan-Williams and Bonner 2009). 

There are no Federally listed aquatic species or designated critical habitat in the vicinity of the 

Red 2 site. However, TPWD has identified numerous rare and protected aquatic species in 

Fannin County. The State-listed rare and protected fish species include: Western sand darter 

(Ammocrypta clara), orangebelly darter (Etheostoma radiosum), goldeye (Hiodon alosoides), 

and taillight shiner (Notropis maculates) (TPWD 2009i). These state rare and protected fish are 

thought to be in the Red River and its tributaries and could be found in the vicinity of the Red 2 

alternative site (Thomas et al. 2007; Hassan-Williams and Bonner 2009). The State-listed 

threatened fish species include: blue sucker (Cycleptus elongates), creek chubsucker 

(Erimyzon oblongus), blackside darter (Percina maculata), paddlefish (Polyodon spathula), and 

shovelnose sturgeon (Scaphirhynchus platorynchus) (Table 9-11). Currently, blue suckers and 

paddlefish are not known to occur in the Red River above the confluence with the Kiamichi 

River, which is below the site (Thomas et al. 2009; Hassan-Williams and Bonner 2009). At one 

time, the shovelnose sturgeon was probably found throughout the river systems in Texas, but 

today, its distribution has been reduced to the Red River below Denison Dam (below Lake 

Texoma Reservoir). The distribution of the blackside darter is now restricted to the streams and 

tributaries of the Red River basin, where it feeds on various aquatic insects and crustaceans. 

The darter is known to migrate from feeding areas in small to medium rivers to spawning areas 

in small tributaries along riffle areas. The creek chubsucker is found in streams associated with 

the Red River, where it feeds on aquatic insects, mollusks and crustaceans. They may spawn 

in shallow areas over a variety of substrates (Thomas et al. 2007; Hassan-Williams and Bonner 

2009; TPWD 2009i). There are no specific studies for these State-listed species in the vicinity 

of the Red 2 alternative site (STPNOC 2010a). 
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February 2011 9-73 NUREG-1937 

Table 9-11. State-Listed Aquatic Species that are Endangered, Threatened, and Species of 

Concern for Fannin County 

Scientific Name Common Name State Status

Fish 

Cycleptus elongates blue sucker T 

Erimyzon oblongus creek chubsucker T 

Percina maculata Blackside darter T 

Polyodon spathula paddlefish T 

Scaphirhynchus platorynchus shovelnose sturgeon T 

Source: State species information provided by TPWD (TPWD 2009d; 35 Texas 

Register 249) 

T = State Listed Threatened. 

The State-listed rare and protected, non-fish species include a number of freshwater mussels: 

rock pocketbook (Arcidens confragosus), Wabash pigtoe (Fusconaia flava), plain pocketbook 

(Lampsilis cardium), White heelsplitter (Lasmigona complanata), common pimpleback 

(Quadrula pustulosa), pistolgrip (Tritogonia verrucosa), and fawnsfoot (Truncilla donaciformis). 

Not much is known about the distribution of these mussels in Fannin County. However, these 

types of freshwater mussels, known as unioid mussels, are found in various water flows, from 

fast moving riffles in streams to quiescent ponds. Each species has adapted to a particular flow 

regime. These unioid mussels have a larval stage called a glochidium. For glochidia to mature 

to juvenile mussels, they must live as a parasite in the gill tissues of a host fish. An important 

component to the distribution of freshwater mussels in various water bodies is associated with 

the relationship between the mussels and the host fish (Strayer 2008). However, for these 

mussel species the host fish species have not been identified. 

Building Impacts 

Impacts of building a cooling water reservoir may be significant depending on the siting of the 

reservoir. At the Red 2 site, the building of a reservoir would flood portions of Brushy Creek 

(STPNOC 2010a). Impacts from onsite building activities that have the potential to cause 

erosion and sedimentation to the local water bodies would be controlled or minimized by the 

implementation of an SWPPP (STPNOC 2010a). During the site visit, observations of the site 

via public roads indicated that there are streams present that are either perennial or intermittent, 

and supply water to the major drainages (including Bois d’Arc Creek, Sheep Creek, and Pattillo 

Branch)(NRC 2009). There are no known surveys or studies of the aquatic resources within 

these drainages. Inundation of small flowing streams would affect those aquatic resources that 

have specific habitat requirements. Fish species that have habitat requirements associated with 

lotic systems (flowing water) are often replaced with species more suited to lentic environments 

(standing water) (Linam et al. 2002). Habitat for these lotic species would likely be lost when 

these water bodies are inundated with the reservoir, including any spawning areas for fish 

species that are dependent on flowing water, e.g., the blackside darter. Most freshwater mussel 
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NUREG-1937 9-74 February 2011 

species are also adapted to a specific flow regime, and the inundation of stream environments 

for the reservoir could affect their distribution in the region (STPNOC 2010a; TPWD 2009i). 

Assuming that aquatic species are ubiquitous in the Red River drainage, and that the habitat 

types provided by the drainages mentioned above are also represented elsewhere in the Red 

River drainage, the impacts from the building the cooling water reservoir would not destabilize 

the aquatic populations of the region. 

New cooling water intake and discharge structures in addition to a cooling water reservoir would 

be required at the Red 2 site (STPNOC 2010a). Building of a new intake and discharge 

structure in the Red River would likely require dredging, pile driving, and other major alterations 

to the shoreline and benthic aquatic habitat. These activities would require permits from the 

Corps and the State of Texas. Building of these structures on the Red River would result in the 

temporary displacement of aquatic biota within the vicinity of both structures. It is expected that 

these biota would return to or recolonize the area after construction is complete. Sedimentation 

due to disturbances of the river bank and bottom during building activities could affect local 

benthic populations. However, the impacts on aquatic organisms would be temporary and 

largely mitigable through implementation of an SWPPP and by use of BMPs (e.g., silt screens) 

(STPNOC 2010a). 

Building transportation routes (heavy haul road or railroad spur), transmission corridors, and 

pipelines for the Red 2 site would also result in the temporary displacement of aquatic biota. 

Locations for these systems have not been identified. Expansion of existing corridors is 

expected to result in minor environmental impacts, while building in new corridors could result in 

more significant impacts. Building these corridors would use BMPs to reduce impacts such that 

they would be temporary and localized (STPNOC 2010a). 

Building the cooling water reservoir for the two new nuclear reactors at the Red 2 site would 

inundate onsite water bodies and flood a portion of Brushy Creek. The habitat for the aquatic 

resources would change, and since most species cannot adapt to the reservoir environment, the 

species would be lost to the site. Thus, the building of the cooling water reservoir would be 

noticeable but not destabilizing to the aquatic resources. Building the intake and discharge 

structures on the Red River and in the new reservoir would affect the aquatic communities but 

the areas would be recolonized after building of these structures was completed. Building of the 

transportation routes, transmission corridors, and pipelines would result in temporary and 

localized effects on aquatic communities. 

Operation Impacts 

To operate two new units at the Red 2 site, water rights for the Red River would have to be 

acquired. Currently, there are not sufficient water rights aggregated to a single point of diversion 

to support the water needed for the Red 2 site (Section 9.3.2.2). The Red River water levels and 

water quality in the vicinity of where an intake structure on the Red River could be located is 
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February 2011 9-75 NUREG-1937 

influenced by releases from Lake Texoma Reservoir. Instream flow studies necessary to 

maintain aquatic resources have not been evaluated for this reach of the river, and effects on 

aquatic resources associated with removal of water for the new reservoir are unknown. 

Impingement, entrainment, and entrapment of organisms from the Red River and from a 

constructed reservoir would likely be the most significant impacts to the aquatic population that 

could occur from operation of two new nuclear units at the Red 2 site. STPNOC states that 

using a closed-cycle cooling system with a cooling water reservoir would consume a maximum 

of 50,000 ac-ft of water per year (STPNOC 2010a). While the Red River is considered to be 

saline and of poor water quality (STPNOC 2010a), the river is known to support populations of 

aquatic biota that have acclimated and thrived under those conditions (Thomas et al. 2007; 

Hassan-Williams and Bonner 2009; McCord 2009). EPA’s design criteria for 316(b) Phase 1 

regulations (66 FR 65255) for intake structures would minimize impacts to aquatic biota in the 

Red River. The design criteria include: (1) closed-cycle cooling system that meets the EPA’s 

Phase I regulations for new facilities; (2) maximum through-screen velocity of 0.15 m/s (0.5 ft/s) 

at the cooling water intake; and (3) intake flow of less than or equal to 5 percent of the mean 

annual flow (STPNOC 2010a). Compliance with these regulations would minimize 

impingement, entrainment, and entrapment impacts to the aquatic biota. 

Operational impacts associated with water quality, physical and thermal characteristics of the 

discharge cannot be determined without additional detailed analysis. The water quality of a 

cooling water reservoir could be maintained by addition of water from the Red River. A cooling 

water reservoir for the Red 2 site would likely evolve in a similar fashion to the MCR at the STP 

site, where, with time, the reservoir has developed similar aquatic resources to that in the lower 

Colorado River and acclimated to the discharges of the operating reactor units. Impacts to the 

Red River would depend on the type of cooling system for the new units, including the volume, 

frequency, and water characteristics of the discharge. These types of impacts can be addressed 

and minimized through operational procedures and the permitting process with TCEQ. 

Operational impacts to aquatic biota from onsite activities and in the transmission line and 

pipeline corridors would also be minimal assuming BMPs are used for corridor maintenance. 

SWPPPs would ensure that impacts to biota from erosion and sedimentation would be minimal 

through the use of silt screens and controls for managing stormwater. These controls would be 

important for habitat quality and survival of benthic biota in the downstream drainages. 

Based on operation of the cooling water system (CWS), impacts to aquatic communities in the 

Red River and reservoir could result from impingement, entrainment, and entrapment as well as 

thermal, chemical, and physical characteristics of the discharge. STPNOC commits to 

compliance with State and Federal regulations for operation of intake and discharge structures 

that would be protective of aquatic resources. Once a community is established in the new 

reservoir, long-term effects from operation of the CWSs are not expected to noticeably alter 

aquatic communities in the Red River and reservoir. 
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NUREG-1937 9-76 February 2011 

Cumulative Impacts 

Within all parts of the Red River drainage between the Denison Dam (below Lake Texoma 

Reservoir) and the confluence of the Red River with the Kiamichi River, the local aquatic 

resources have adapted to the construction of Valley Lake for the Valley Power Plant, but may 

be affected by the building of future planned power plants. The aquatic resources of Brushy 

Creek and the Red River adapted to the construction of Valley Lake and the water needs for the 

Valley Power Plant. Valley Lake is open to the public for recreational fishing. In 2008, the 

Pattillo Branch Power Company, LLC, submitted a permit application to TCEQ for construction 

of a gas-powered electric-generating plant approximately 3 mi south of the Red 2 site 

(TCEQ 2009a). The construction of this plant would likely have similar impacts to the aquatic 

biota as those discussed for the building of the Red 2 site. If the proposed Pattillo Branch 

Power Plant also includes a reservoir, the cumulative loss of stream and drainage habitat would 

be greater than the loss of habitat from the Red 2 reservoir. In addition, these actions may 

affect water flow to Bois d’Arc Creek and degrade the biological function of this water body that 

is designated as an ecologically significant stream segment. 

The Red River below Lake Texoma Reservoir has numerous tributaries, including Brushy Creek 

and Valley Lake. It is assumed that the proposed new Pattillo Branch Power Plant would divert 

additional water from the Red River. The TCEQ would evaluate as part of considering the 

aggregation of water rights for the Red 2 site if the instream flow in the Red River for the 

existing Valley Power Plant, the proposed Pattillo Branch Power Plant, and the two new units at 

Red 2 would be sufficient for protection of aquatic life (NRC 2009). If instream flows are 

insufficient for protection of aquatic life, TCEQ could make changes to available water rights, 

and that could affect the water availability for future power production facilities (NRC 2009). Of 

particular concern would be the potential to affect the State-listed species in the area, e.g., the 

shovelnose sturgeon that now has a distribution limited to the Red River (Thomas et al. 2007; 

Hassan-Williams and Bonner 2009; TPWD 2009i). 

Continued urbanization and agricultural practices could affect aquatic communities in the Red 2 

geographic area of interest in the foreseeable future. Expansion of urban areas in the Red 

River drainage could increase water use, decrease available water for aquatic resources, and 

increase nonpoint pollution. The effects of continued agricultural practices could result in 

additional habitat loss and/or degradation due to irrigation using surface waters and 

groundwater withdrawal, point and non-point source pollution, siltation, and bank erosion. 

As mentioned in Section 9.3.2.3, GCC could result in regional increases in the frequency of 

severe weather, decreases in annual precipitation, and increases in average temperature 

(GCRP 2009). The decrease in precipitation combined with elevated water temperatures and 

evaporation could result in more frequent droughts, which could reduce aquatic habitat. Loss of 

habitat could cause shifts in species ranges, diversity, and abundance in the geographic area of 

interest for the Red 2 site (GCRP 2009). Specific predictions on potential impacts to aquatic 
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February 2011 9-77 NUREG-1937 

species and their habitat in this region resulting from GCC are inconclusive at this time. 

Because of the regional nature of climate change, the impacts related to GCC would be similar 

for all the alternative sites, as they are all in the Great Plains Region. 

Based on building and operation of two new nuclear units at the Red 2 alternative site and other 

projects and influences in the region of influence for aquatic resources, the cumulative impacts 

would be noticeable but not destabilizing. All these activities would alter the aquatic habitats 

and potentially change the species composition and diversity in the affected water bodies. The 

incremental contribution of building and operating the two new reactors at the Red 2 site to the 

cumulative impacts within the geographic area of interest would be substantial. 

Summary 

STPNOC has indicated that building of a cooling water reservoir at the Red 2 site would 

inundate existing water bodies and destroy habitat for aquatic resources that are dependent on 

flowing water. The review team concludes that the impacts from building two new nuclear units 

at the Red 2 site would be noticeable but not destabilizing to the aquatic resources. The review 

team also concludes that the impacts from operation of two new units would be minimal. Based 

on the information provided by STPNOC and the review team’s independent evaluation, the 

review team concludes that the cumulative impacts of building and operating two new reactors 

on the Red 2 site combined with other past, present, and future activities on most aquatic 

resources in the Red River drainage would be MODERATE. The incremental contribution of 

building and operating the two new reactors at the Red 2 site to the cumulative impacts within 

the geographic area of interest would be significant. 

9.3.2.5 Socioeconomics 

The following impact analysis includes impacts from building activities and operations. The 

analysis also considers other past, present, and reasonably foreseeable future actions that 

impact socioeconomics, including other Federal and non-Federal projects listed in Table 9-8. 

For the analysis of socioeconomic impacts at the Red 2 site, the geographic area of interest is 

considered to be the 50 mi region centered on the Red 2 site with special consideration of 

Fannin and Grayson Counties as that is where the review team expects socioeconomic impacts 

to be the greatest. In evaluating the socioeconomic impacts of site development and operation 

at the Red 2 site near Savoy in Fannin County, the review team undertook a reconnaissance 

survey of the site using readily obtainable data from the Internet or published sources. 

Physical Impacts 

Many of the physical impacts of building and operation would be similar regardless of the site. 

Building activities can cause temporary and localized physical impacts such as noise, odor, 

vehicle exhaust, vibration, shock from blasting (if used), and dust emissions. The use of public 
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NUREG-1937 9-78 February 2011 

roadways, railways, and waterways would be necessary to transport construction materials and 

equipment. Offsite areas that would support building activities (e.g., borrow pits, quarries, and 

disposal sites) would be expected to be already permitted and operational. 

Potential impacts from station operation include noise, odors, exhausts, thermal emissions, and 

visual intrusions (the latter are discussed under aesthetics and recreation). New units would 

produce noise from the operation of pumps, cooling towers, transformers, turbines, generators, 

and switchyard equipment. Traffic at the site also would be a source of noise. Any noise 

coming from the proposed STP site would be controlled in accordance with standard noise 

protection and abatement procedures. This practice also would be expected to apply to all 

alternative sites, including the Red 2 site. Commuter traffic would be controlled by speed limits. 

Good road conditions and appropriate speed limits would minimize the noise level generated by 

the workforce commuting to the alternative site. 

The new units at the Red 2 site would likely have standby diesel generators and auxiliary power 

systems. Permits obtained for these generators would ensure that air emissions comply with 

applicable regulations. In addition, the generators would be operated on a limited, short-term 

basis. During normal plant operation, new units would not use a significant quantity of 

chemicals that could generate odors that exceed odor threshold values. Good access roads 

and appropriate speed limits would minimize the dust generated by the commuting workforce. 

Based on the information provided by STPNOC and the review team’s independent evaluation, 

the review team concludes that the physical impacts of building and operating two nuclear units 

at the Red 2 site would be minimal. 

Demography 

The Red 2 site is located in Fannin County, 3.7 mi north of the city of Savoy (2008 population 

895) and 12.2 mi southeast of Denison (2008 population 24,001), approximately 20 mi east of 

Sherman (2008 population 38,077) and within 50 mi of the outer edges of the Dallas-Fort Worth 

(DFW) Metroplex (2008 population 6,300,006) (USCB 2009a). The Sherman-Denison 

metropolitan area (located in Grayson County) has an estimated 2008 population of 118,804 

(USCB 2009b). After World War II, Fannin County’s population declined up until the 1970s 

when it slowly began to rise again to its current 2008 population of 33,229 (TSHA 2009b). 

STPNOC estimated the peak number of building workers would be 5950. Approximately 900 

operations workers would also be onsite during the final phase of building activities (STPNOC 

2010a). Based on assumptions in Section 4.4 concerning in-migration for Units 3 and 4 in 

Matagorda County, and for comparability with the analysis in that section, the review team 

assumed that 50 percent or 2975 construction workers would in-migrate. Because no 

information is available on where the workforce would live, the review team assumed that half of 

the plant workforce would move to Fannin County and the other half to Grayson County. Collin 

County and other counties nearer Dallas-Fort Worth would likely see an in-migration of workers 
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February 2011 9-79 NUREG-1937 

as well, but considering the large populations of these counties and the relatively small number 

of in-migrants they would be easily absorbed with no measurable impact. Eighty percent of inmigrating construction workers would bring a family. All operations workers would in-migrate 

and all would bring a family. A family size of 3.25 was used for construction workers for a total 

peak site development related population increase of 8330 (7735 in-migrating workers and 

family members and 595 workers without family). The average family size of 2.74 for the 

operating workforce (see Section 5.4) would result in a total in-migrating operations-related 

population of 2466 (900 operations workers plus family). Therefore, the total expected inmigrating population (site development and operations) at peak building would be 10,796. 

Since the assumed in-migrating population during the building period would be less than 

5 percent of the total population for Grayson County and 16 percent for Fannin County, the 

demographic impacts of site development are expected to be much less for Grayson County 

than for the smaller Fannin County. If the facility is constructed and commences operations, the 

operational workforce would number about 959 workers, 900 of whom would already be at the 

site during peak site development and are included in the above analysis, meaning that there 

would be very little demographic impact during operations in either county. Based on the 

information provided by STPNOC and the review team’s independent evaluation, the review 

team concludes that the demographic impacts of building and operating two nuclear units at the 

Red 2 site would be noticeable mainly in Fannin County during the building period, because of 

the relatively significant ratio of in-migrating to resident population. 

Taxes and Economy 

Tax revenues to the local economies and the State would come in several different forms, as 

discussed in Sections 4.4 and 5.4. As described in Section 5.4.3.2, STPNOC estimates it would 

spend $60 million on annual expenditures for goods and services related to the new units of 

which about 20 percent ($12 million) would be spent locally (STPNOC 2010a). STPNOC 

estimated if the units were 100 percent taxable, annual franchise taxes for Units 3 would be 

$4.7 to $5.4 million and Unit 4 would have payments of $3.9 to $4.7 million per year, which 

would represent less than 1 percent of the State’s annual franchise tax revenues. 

Based on the assumptions and methodology detailed in Section 5.4.3.2, the review team 

estimated that annual property taxes would range from $6.10 million to $13.86 million, which 

would represent a 73 to 165 percent increase over the 2008 Fannin County taxes levied of 

$8.4 million. STPNOC notes that local entities may also receive tax benefits from the 

hypothetical new reactors (STPNOC 2010a). Savoy Independent School District (ISD), for 

example, is the school district that encompasses the land on which the plant would be built and 

would be a likely recipient of considerable property tax benefits. 

Economic impacts would be spread across the 50-mi region but would be greatest in Fannin 

County and to a lesser extent Grayson County. Fannin County per capita income for 2007 was 
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NUREG-1937 9-80 February 2011 

$25,258 and $28,901 for Grayson County. The 2008 unemployment rate for Fannin County and 

Grayson County was 5.9 percent and 5.3 percent, respectively (Texas Association of Counties 

2009a, b). The wages and salaries of the building and operations workforce would stimulate the 

economy and could result in increases in business activity, particularly in the retail and service 

sectors. This would have a positive impact on the business community and could provide 

opportunities for new businesses and increased job opportunities for local residents. Based on 

the information provided by STPNOC and the review team’s independent evaluation, the review 

team concludes that the tax and economic impacts of building and operating two nuclear units 

at the Red 2 site would be significant and beneficial. 

Transportation and Housing 

Primary access to the site is from the south on U.S. Route 82 which runs between Sherman and 

Bonham. U.S. 82 is four-lanes in Grayson County but narrows to two-lanes before entering 

Fannin County. Commuters from Denison would use U.S. 69 to its intersection with U.S. 82. 

Other secondary roads serving the site are Farm-to-Market (FM) 1897, FM 1753 and FM 1752 

(provides access to Valley Power Plant). All three of these roads are two-lanes and in good 

condition (STPNOC 2009a). The Red 2 site is accessed by a one lane unimproved road not 

maintained by Texas Department of Transportation (TxDOT) that would need major upgrades 

and a portion of FM 1752 that would need widening (STPNOC 2010a). The most likely pinch 

points would be the intersection of U.S. 69 and U.S. 82 and also at FM 1897 and FM 1752. 

Approximately 4.2 mi of rail would need to be constructed. The review team expects the 

transportation impacts from building a plant at the Red 2 site could be adverse and noticeable, 

may change traveler behavior, depending on commuter patterns of the workers at the Red 2 site 

and those at the Valley Power Plant (currently mothballed), and would warrant mitigation. 

Operation impacts would be significantly lower than the building phase impacts of traffic due to 

the much smaller workforce and because roads would have been improved during the building 

phase. 

The U.S. Census Housing Profile for Fannin County estimated a total housing stock of 

13,571 units with a rental vacancy rate of 8.5 percent. Approximately 2146 housing units were 

unoccupied at the time of the survey (USCB 2009c). The U.S. Census Housing Profile for 

Grayson County estimated a total housing stock of 51,733 units with a rental vacancy rate of 

7.6 percent. Approximately 7103 housing units were unoccupied at the time of the survey 

(USCB 2009d). The review team expects that the in-migrating workforce could be absorbed 

into the existing housing stock in Grayson County and the region without a measureable impact, 

but the impacts to Fannin County could be more significant, given the small number of vacant 

housing units. Based on the information provided by STPNOC and the review team’s 

independent evaluation, the review team concludes that the transportation and housing impacts 

of building and operating two nuclear units at the Red 2 site would be noticeable. 
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February 2011 9-81 NUREG-1937 

Public Services and Education 

In-migrating construction workers and plant operations staff would likely impact local municipal 

water, wastewater treatment facilities, and other public services in the region. These impacts 

would likely be in proportion with the demographic impacts experienced in the region, unless 

these resources have excess capacity or are particularly strained during building, which would 

decrease or increase the impact, respectively. For example, the largest water treatment 

facilities in both Fannin County and Grayson County have water capacity available that is 

roughly two to five times current average daily consumption (EPA 2009b; TCEQ 2010a), so 

while Fannin County in particular may have to build considerable distribution infrastructure, 

neither county is likely to be water capacity limited. The in-migrating construction workers 

represent a small portion of the total population of Grayson County and would likely not have a 

noticeable impact on their public services. In the smaller Fannin County construction-related 

impacts could place a strain on some public services, based on the county’s proportionally 

larger in-migrating population. During operations the impact on public services would likely be 

minimal in all areas. 

Fannin County has nine independent school districts with 25 schools, and Grayson County has 

13 independent school districts with 69 schools. The 2007-2008 student enrollments for Fannin 

and Grayson Counties are 5620 students and 21,081 students, respectively (NCES 2009). The 

review team expects a peak building-related increase of about 2537 students (1269 in each 

county). The in-migrating students would likely represent a noticeable but not significant impact 

to schools in Grayson County due to the 6 percent increase in overall students. However, the 

increase would be a 23 percent increase in the student population in Fannin County, where the 

review team expects the impact to be significant and potentially destabilizing to this school 

system. During operation, this impact on schools would be significantly less due to the lower 

number of in-migrating students. Based on the information provided by STPNOC and the 

review team’s independent evaluation, the review team concludes that the public service and 

education impacts of building and operating two nuclear units at the Red 2 site would be 

significant. 

Aesthetics and Recreation 

Recreation in the area includes historic Texas Lakes Trail, Lake Davy Crockett Recreational 

Area, Caddo Wildlife Management Area (WMA) and Ray Roberts Lake State Park and WMA. 

These areas offer boat access, picnicking and camping. The Red 2 site is located near Valley 

Lake which supports the Valley Power Plant. Any recreation that occurs on Valley Lake is 

private but would be affected by building the nuclear plant (STPNOC 2010a). The building and 

operation of transmission lines to support the site also would have an aesthetic impact on the 

region. The NRC review team concludes that the visual impact associated with site 

development and operation of two tall, relatively isolated nuclear units on this site would have a 

noticeable impact on the visual aesthetic resources in the area. Impacts on aesthetic resources 
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NUREG-1937 9-82 February 2011 

would not be destabilizing because these resources are already significantly affected by the 

presence of the nearby Valley Power Plant. The nuclear plant would not adversely affect 

boating access or access to picnicking or camping sites, therefore, it is expected that there 

would be minimal impacts on recreation. Based on the information provided by STPNOC and 

the review team’s independent evaluation, the review team concludes that the aesthetic and 

recreation impacts of building and operating two nuclear units at the Red 2 site would be 

noticeable. 

Summary of Project-Related Socioeconomic Impacts 

Physical impacts on workers and the general public include impacts on existing buildings, 

transportation, aesthetics, noise levels, and air quality. Social and economic impacts span 

issues of demographics, economy, taxes, infrastructure, and community services. In summary, 

on the basis of information provided by STPNOC and the review team’s independent evaluation, 

the review team concludes that the impacts of the building and operation of two nuclear units at 

the Red 2 site on socioeconomics would be minimal and adverse for Grayson County and most 

of the region but could be noticeable but not destabilizing for Fannin County in terms of 

transportation, housing, and public services and significant and potentially destabilizing for 

education impacts during the building phase. During operation, these impacts are expected to 

be minimal. The impacts on aesthetics are expected to be noticeable but not destabilizing. The 

impacts on the Fannin County economy and tax base during plant development and operation 

likely would be significant and beneficial. 

Cumulative Impacts 

For the analysis of socioeconomic impacts at the Red 2 site, the geographic area of interest is 

considered to be the 50-mi region centered on the Red 2 site with special consideration of 

Fannin and Grayson Counties as that is where the review team expects socioeconomic impacts 

to be the greatest. Fannin County has historically had an agricultural based economy centered 

mainly on cotton but during the late 20th century wheat was the only major crop to increase 

production as did several other small crops. Stock farming moved from milk cattle to beef cattle 

and Fannin County also saw an increase in banking and service businesses after World War II. 

With the opening of the first oilfield in Grayson County in the 1930s the local economy was 

changed. By 1970, the County was producing 120 million barrels of oil a day and became a 

manufacturing and trade center in the 1970’s and 1980’s with 50 percent of the labor force 

employed in these two sectors (TSHA 2009c). After World War II Fannin County’s population 

declined up until the 1970s when it slowly began to rise again to its 2008 population of 33,229 

(TSHA 2009b). 

In addition to assessing the marginal socioeconomic impacts from the building and operations of 

two additional nuclear units on the Red 2 site, the cumulative impact is also considered. The 

cumulative analysis considers other past, present, and reasonably foreseeable future actions 
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February 2011 9-83 NUREG-1937 

that could contribute to the cumulative socioeconomic impacts on a given region, including other 

Federal and non-Federal projects and those projects listed in Table 9-8. For the analysis of 

socioeconomic impacts at the Red 2 site, the geographic area of interest is considered to be the 

50-mi region centered on the Red 2 site. 

The projects identified in Table 9-8 have or would contribute to the demographics, economic 

climate, and community infrastructure of the region and generally result in increased 

urbanization and industrialization. However, many impacts such as those on housing or public 

services are able to adjust over time, particularly with increased tax revenues. Furthermore, 

state and county plans along with modeled demographic projections include forecasts of future 

development and population increases. Because the other projects described in Table 9-8 do 

not include any significant reasonably foreseeable changes in socioeconomic impacts within 

50 mi of the Red 2 site, the review team determined there would not be any significant 

additional cumulative socioeconomic impacts in the region from those activities. Any economic 

impacts associated with activities listed in Table 9-8 would have been considered as part of the 

socioeconomic baseline, except for the Pattillo Branch Power Company natural gas fired power 

plant near Savoy. The project reportedly would create “hundreds” of construction jobs and 25 to 

30 operations jobs. The project would be completed in 2012 (North Texas eNews 2010b). For 

that reason, Pattillo site employment would be declining just as site employment at Red 2 would 

be beginning. Because of this timing and Pattillo’s relatively small size, the review team does 

not believe that the Pattillo plant would significantly exacerbate any socioeconomic impacts from 

the Red 2 site. The Lake Ralph Hall project represents another reasonably foreseeable activity 

in Fannin County and within 30 mi of the Red 2 site, as is Bois d’Arc Creek Reservoir, located 

within 20 mi of the Red 2 site. While these projects could impose additional socioeconomic 

impacts, the planned starting and completion dates and the level of activity for these projects 

are uncertain. Therefore, the review team concluded that for purposes of this alternative site 

analysis, the socioeconomic impacts of these projects could not be quantitatively evaluated. 

However, although the timing of the impacts is not known, the review team expects that the 

following effects may occur. The review team would expect temporary increases in economic 

activity, population and traffic during the building period; decreases in existing property tax base 

which may or may not be offset by values of recreational development and other improvements 

related to the reservoir. In addition, during reservoir operations, depending on the level of 

development (and population), there may be increases in the demand for infrastructure and 

community services. There is a possibility that recreational opportunities would increase. 

The review team concludes that the physical impacts of the building and operation of a nuclear 

plant at the Red 2 site would be SMALL for the entire 50 mi region. Socioeconomic impacts 

would be SMALL and adverse for Grayson County and most of the region but could be 

MODERATE and adverse for Fannin County in terms of demographic, transportation, housing, 

public services, and aesthetics; and LARGE and adverse for education during the building 

phase. The impacts on the economy and tax base during plant building and operation likely 
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NUREG-1937 9-84 February 2011 

would be beneficial and LARGE in Fannin County but SMALL for the rest of the 50-mi region. 

Building and operating a new plant at the Red 2 site would make a significant, incremental 

contribution to these impact levels. 

9.3.2.6 Environmental Justice 

The following impact analysis includes impacts from building activities and operations. The 

analysis also considers other past, present, and reasonably foreseeable future actions that 

impact environmental justice, including other Federal and non-Federal projects listed in 

Table 9-8. The cumulative environmental justice impacts were assessed for the 50-mi region 

centered on the Red 2 site. In 2000, the 50-mi region around the Red 2 site was characterized 

as 5.7 percent Black, 1.7 percent American Indian and Alaskan Native, 3.6 percent Asian, 

0.04 percent Hawaiian and Other Pacific Islander, 4.1 percent all other races, and 2.3 percent 

two or more races, 9.2 percent Hispanic or Latino and 6.5 percent low-income (STPNOC 2010a). 

The review team identified a total of 631 census block groups within the 50-mi region (which 

included portions of Oklahoma), 41 of which were classified as minority populations, with one of 

them in Fannin County and seven of them in Grayson County (USCB 2000a, b). None of these 

populations are within 10 mi of the Red 2 alternative site. The review team also found 19 

census block groups classified as low income in the 50-mi region, with none in Fannin County 

and 2 in Grayson County (USCB 2000c, d). None of these populations are within 10 mi of the 

Red 2 alternative site. See Figure 9-7 and Figure 9-8 for the location of minority or low-income 

populations within the 50-mi region. Almost all of the potential physical impacts of building and 

operation would occur within the vicinity of the Red 2 site and Figure 9-7 and Figure 9-8 show 

no minority or low-income block groups within 10 mi of the Red 2 site. The review team did not 

locate any minority or low-income populations downstream of the Red 2 site on Brushy Creek or 

the Red River within 50 mi of the Red 2 site. The review team’s analysis did not find any 

information suggesting that minority or low-income populations in the area were dependent on 

natural resources that would be adversely affected by a nuclear power plant at the Red 2 site. 

Finally, the review team did not identify any potential pathways by which any building or 

operations activity could affect any minority and low-income populations outside of Fannin and 

Grayson Counties. The review team determined that for the Red 2 site there would be no 

disproportionately high and adverse impacts on minority or low-income populations from 

building and operating two nuclear units and therefore the environmental justice impacts can be 

characterized as minimal and adverse. 

The projects identified in Table 9-8 likely did not or will not contribute to environmental justice 

impacts of the region. Based on information provided by STPNOC and the review team’s 

independent evaluation, the review team concludes that there would likely not be any 

disproportionately high and adverse environmental justice cumulative impacts from building and 

operating two nuclear units at the Red 2 site and therefore any environmental justice-related 

impacts would be SMALL and adverse. 
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February 2011 9-85 NUREG-1937 

Figure 9-7. Block Groups with Minority Populations Meeting Environmental Justice Selection 

Critera within 50 mi of the Red 2 Alternative Site (USCB 2000a,b)
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Figure 9-8. Block Groups with Low-Income Populations Meeting Environmental Justice 

Selection Criteria Within 50 mi of the Red 2 Alternative Site (USCB 2000c,d)
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February 2011 9-87 NUREG-1937 

9.3.2.7 Historic and Cultural Resources 

The following impact analysis includes impacts from building activities and operations at the 

Red 2 site. The analysis also considers other past, present, and reasonably foreseeable future 

actions that may impact historic and cultural resources, including other Federal and non-Federal 

projects listed in Table 9-8. For the analysis of cultural impacts at the Red 2 site, the 

geographic area of interest is considered to be the APEs that would be defined for this site. 

This includes the physical APE, defined as the area directly affected by the site development 

and operation activities at the site and transmission lines, and the visual APE. The visual APE 

is defined as an additional 1-mi radius around the physical APE consistent with the discussion in 

Section 2.7 about the maximum distance from which the structures can be seen. 

Reconnaissance activities in a cultural resource review have particular meaning. Typically, for 

example, it includes preliminary field investigations to confirm the presence or absence of 

cultural resources. However, in developing this EIS, the review team relied upon 

reconnaissance-level information to perform its alternative site evaluation, in accordance with 

ESRP 9.3 (NRC 2000). Reconnaissance-level information is data that are readily available from 

agencies and other public sources. It can also include information obtained through visits to the 

site area. To identify the historic and cultural resources at the Red 2 site, the following 

information was used: 

• STPNOC ER (STPNOC 2010a) - including the Texas Historical Commission’s (THC’s) 

Texas Archeological Sites Atlas and 

• NRC Alternative Sites Visit August 2009 

The Red 2 site is a greenfield site located 1.8 mi north of the existing Valley Power Plant. 

Historically, the site and vicinity were largely undisturbed and likely contained intact 

archaeological sites associated with the past 10,000 years of human settlement. Over time, the 

area has been disturbed by rural development and cleared for agricultural purposes. Based on 

reconnaissance-level information, the physical and visual APEs if the proposed plant were to be 

sited at the Red 2 site do not appear to have any historic properties likely to be affected by 

building or operating new units. No archaeological and/or architectural surveys have been 

conducted at the Red 2 site. 

Nine historic properties listed on the National Register of Historic Places are found in Fannin 

County, Texas, but all are located more than 10 mi away from the Red 2 site in towns within a 

protected area (Caddo National Grasslands). Six archaeological sites have been recorded 

along Valley Lake, within 2 mi of the Red 2 site. In addition, the Virginia Point Cemetery, which 

is still active, is located 0.75 mi west of the Red 2 site. Near the cemetery is a Texas Historic 

Landmark, the Virginia Point Methodist Church, the oldest church in Fannin County (STPNOC 

2010a). Neither the cemetery nor the church is listed on the National Register. The project has 

the potential to affect resources through visual impacts from buildings and transmission lines. 
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NUREG-1937 9-88 February 2011 

Should these two properties be subsequently listed on the National Register or additional 

properties be identified, then these impacts may result in significant alterations to the physical 

and visual landscape within the geographic area of interest. 

To accommodate building two new nuclear generating units at the Red 2 site, STPNOC would 

need to clear approximately 800 ac for the main power plant site, approximately 81 ac for offsite 

transportation and pipeline corridors, and up to 1700 ac for a new reservoir (STPNOC 2010a). 

In the event that the Red 2 site was chosen for the proposed project, identification of cultural 

resources would be accomplished through cultural resource surveys and consultation with the 

State Historic Preservation Officer (SHPO) at THC, Tribes and interested parties. The results 

would be used in the site planning process to avoid cultural resources impacts. In the event 

significant cultural resources were identified by these surveys, the review team assumes that 

STPNOC would develop protective measures in a manner similar to those for the STP site. 

These procedures are detailed in STPNOC’s Addendum #5 to procedure No OPGP03-ZO-0025 

Rev. 12 (Unanticipated Discovery of Cultural Resources) (STPNOC 2008c); the procedures 

include notification of the SHPO at the THC and affected Tribe(s) or other parties depending on 

the nature of the find. 

Section 9.3.2.1 describes the transmission line corridors. There are no existing transmission 

corridors connecting directly to the Red 2 site. However, there are multiple 345-kV transmission 

lines connecting to the Valley Power Plant (STPNOC 2010a). A new transmission corridor 

would need to be created to connect the Red 2 site to these lines. In the event that the Red 2 

site was chosen for the proposed project, the review team assumes that transmission corridorrelated cultural resource surveys and procedures would be conducted in a manner similar to 

that for the STP site. In this context, the developer of transmission systems in the region, 

Oncor, would file an Environmental Assessment with the Public Utility Commission of Texas 

(PUCT) outlining practices to consider community, historic, and aesthetic values and prudent 

avoidance. During construction of such systems, should Oncor or its contractors encounter any 

archaeological artifacts or other cultural resources, work would halt immediately in the vicinity of 

the resource, the discovery would be reported to the THC, and Oncor would take action as 

directed by the THC. The established practice of conducting cultural and historic surveys as 

part of the Environmental Assessment and process for communicating with the THC for 

inadvertent discoveries ensures that offsite cultural and historic resources would be protected. 

Past actions in the geographic area of interest that have similarly affected historic and cultural 

resources include rural development and agricultural development and activities associated with 

these land disturbing activities such as road development. No current or planned projects were 

identified in Table 9-8 that may contribute to cumulative impacts on historic and cultural 

resources in the geographic area of interest. 

Activities associated with building two nuclear units and supporting facilities that can potentially 

destabilize important attributes of historic and cultural resources include land clearing, 
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February 2011 9-89 NUREG-1937 

excavation, and grading activities. Given STPNOC’s site planning process and no known 

cultural resources at the Red 2 site based on reconnaissance-level information, the impacts to 

cultural resources due to site development activities would be negligible. 

Additionally, visual impacts from transmission lines may result in significant alterations to the 

visual landscape within the geographic area of interest. Given that there are no known cultural 

resources where the historic setting and character of the resources are important, the visual 

impacts would be negligible. The review team assumes that the transmission system 

developer, i.e., Oncor, would continue to consider cultural and historic resources and associated 

aesthetic values in a manner consistent with the preparation of Environmental Assessments 

needed to support its filings before the PUCT before an approval is granted. 

Impacts on historic and cultural resources from operation of two new nuclear generating units at 

the Red 2 site include those associated with the operation of new units and maintenance of 

transmission corridors. The review team assumes that the same procedures currently used by 

STPNOC would be used for onsite and offsite maintenance activities. Consequently, the 

incremental effects of the maintenance of transmission-line corridors and operation of the two 

new units and associated impacts on the cultural resources would be negligible for the physical 

and visual APEs. 

The geographic area of interest for cumulative impacts to historic and cultural resources at 

Red 2 corresponds to the physical and visual APEs defined for the site. None of the activities 

identified in Table 9-8 are located in the geographic area of interest and none would significantly 

affect historic and cultural resources in a manner similar to those associated with the operation 

of two new units. 

Cultural resources are non-renewable; therefore, the impact of destruction of cultural resources 

is cumulative. Based on the information provided by the applicant and the review team’s 

independent evaluation, the review team concludes that the cumulative impacts from building 

and operating two new nuclear generating units on the Red 2 site would be SMALL. This 

impact level determination reflects no known cultural resources that could be affected; 

STPNOC’s site planning process, and no current or planned projects in the geographic area of 

interest, including the physical and visual APEs. However, if the Red 2 site was to be 

developed, then cultural resource surveys may reveal important historic properties that could 

result in greater cumulative impacts. 

9.3.2.8 Air Quality 

The following impact analysis includes impacts from building activities and operations. The 

analysis also considers other past, present, and reasonably foreseeable future actions that 

impact air quality, including other Federal and non-Federal projects listed in Table 9-8. The 
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NUREG-1937 9-90 February 2011 

geographic area of interest for the Red 2 site is Fannin County, which is in the Metropolitan 

Dallas-Fort Worth Intrastate Air Quality Control Region (40 CFR 81.39). 

The emissions related to building and operating a nuclear power plant at the Red 2 alternative 

site would be similar to those at the STP site. The air quality attainment status for Fannin 

County as set forth in 40 CFR 81.344 reflects the effects of past and present emissions from all 

pollutant sources in the region. Fannin County is not out of attainment of any National Ambient 

Air Quality Standard. 

The atmospheric emissions related to building and operating a nuclear power plant at the STP 

site in Matagorda County, Texas, are described in Chapters 4 and 5. The criteria pollutants 

were found to have a SMALL impact. In Chapter 7, the cumulative impacts of the criteria 

pollutants at the STP site were evaluated and also determined to be MODERATE principally 

because of a nearby major source; absent that source, the cumulative impacts would be 

SMALL. 

Reflecting on the projects listed in Table 9-8, the most significant are the Valley Power Plant 

and the Pattillo Branch Power Plant. Effluents from power plants such these are typically 

released through stacks and with significant vertical velocity. Other industrial projects listed in 

Table 9-8 would have de minimis impacts. Given that these projects would be subject to 

institutional controls, it is unlikely that the air quality in the region would degrade to the extent 

that the region is in nonattainment of National Ambient Air Quality Standards. 

The air quality impact of Red 2 site development would be local and temporary. The distance 

from building activities to the site boundary would be sufficient to generally avoid significant air 

quality impacts. There are no land uses or projects, including the aforementioned sources, that 

would have emissions during site development that would, in combination with emissions from 

the Red 2 site, result in degradation of air quality in the region. 

Releases from operation of two units at the Red 2 site would be intermittent and made at low 

levels with little or no vertical velocity. The air quality impacts of the Valley Power Plant are 

included in the baseline air quality status. The air quality impacts of the Pattillo Branch Power 

Plant would be similar to the air quality impacts discussed in Section 9.2.2.2, which could be 

noticeable but not destabilizing. The cumulative impacts from emissions of effluents from the 

Red 2 site and the aforementioned sources could be noticeable but not destabilizing. 

The cumulative impacts of greenhouse gas emissions related to nuclear power are discussed in 

Section 7.6. The impacts of the emissions are not sensitive to location of the source. 

Consequently, the discussion in Section 7.6 is applicable to a nuclear power plant located at the 

Red 2 site. The review team concludes that the national and worldwide cumulative impacts of 

greenhouse gas emissions are noticeable but not destabilizing. The review team further 
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February 2011 9-91 NUREG-1937 

concludes that the cumulative impacts would be noticeable but not destabilizing, with or without 

the greenhouse gas emissions of the project at the Red 2 site. 

Cumulative impacts to air quality resources are estimated based in the information provided by 

STPNOC and the review team’s independent evaluation. Other past, present and reasonably 

foreseeable future activities exist in the geographic areas of interest (local for criteria pollutants 

and global for greenhouse gas emissions) that could affect air quality resources. The 

cumulative impacts on criteria pollutants from emissions of effluents from the Red 2 site, other 

projects, and the Valley Power Plant and the Pattillo Branch Power Plant could be noticeable 

but not destabilizing, principally as a result of the contribution of these two sources. The 

national and worldwide cumulative impacts of greenhouse gas emissions are noticeable but not 

destabilizing. The review team concludes that the cumulative impacts would be noticeable but 

not destabilizing, with or without the greenhouse gas emissions from the Red 2 site. The review 

team concludes that cumulative impacts from other past, present, and reasonably foreseeable 

future actions on air quality resources in the geographic areas of interest would be SMALL to 

MODERATE for criteria pollutants and MODERATE for greenhouse gas emissions. The 

incremental contribution of impacts on air quality resources from building and operating two 

units at the Red 2 site would be insignificant for both criteria pollutants and greenhouse gas 

emissions. 

9.3.2.9 Nonradiological Health 

The following impact analysis includes impacts from building activities and operations. 

The analysis also considers other past, present, and reasonably foreseeable future actions 

that impact nonradiological health, including other Federal and non-Federal projects listed in 

Table 9-8. For the analysis of nonradiological health impacts at the Red 2 alternative site, the 

geographic area of interest is considered to include projects within a 5-mi radius from the site’s 

center based on the localized nature of the impacts. For impacts associated with transmission 

lines, the geographic area of interest is the transmission line corridor. 

The building activities that have the potential to impact the health of members of the public and 

workers include exposure to dust and vehicle exhaust, occupational injuries, noise, and the 

transport of construction materials and personnel to and from the site. The operation-related 

activities that have the potential to impact the health of members of the public and workers 

includes exposure to etiological agents, noise, EMFs, and impacts from the transport of workers 

to and from the site. 

Building Impacts 

Nonradiological health impacts to construction workers and members of the public from building 

two new nuclear units at the Red 2 site would be similar to those evaluated in Section 4.8 for the 

STP site. The impacts include noise, vehicle exhaust, dust, occupational injuries, and 
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NUREG-1937 9-92 February 2011 

transportation accidents, injuries, and fatalities. Applicable Federal and State regulations on air 

quality and noise would be complied with during the site preparation and building phase. The 

incidence of construction worker accidents would not be expected to be different from the 

incidence of accidents estimated for the STP site. The Red 2 site is located in a rural area and 

nonradiological health impacts from building would likely be negligible on the surrounding 

populations. 

The ER (STPNOC 2010a) indicated that there may be significant impacts on the transportation 

network in the vicinity of the Red 2 site and mitigation would be warranted. The impacts in the 

vicinity of the Red 2 site include traffic associated with the existing Valley Power Plant. 

Interactions between the traffic destined for the Red 2 site nuclear power plant project and the 

Valley Power Plant are likely to increase the nonradiological health effects from traffic accidents 

in the vicinity of the Red 2 site. The additional injuries and fatalities from traffic accidents 

involving transportation of materials and personnel for building of a new nuclear power plant at 

the Red 2 site would be similar to those evaluated in Section 4.8.3 for the STP site and would 

represent a small fraction (less than 5 percent) of the total traffic fatalities in Fannin County. 

Past actions in the geographic area of interest that have similarly affected the public and 

workers from nonradiological resources include the construction of the Valley Power Plant and a 

wastewater treatment facility for the City of Bells. There are no major current construction 

projects in the geographic area of interest that would cumulatively impact nonradiological health. 

Proposed future actions that would impact nonradiological health in a similar way to 

development at the Red 2 site would include the proposed Pattillo Branch Power Plant, 

transmission line development and/or upgrading throughout the designated geographic area of 

interest, and future urbanization. 

Operational Impacts 

Nonradiological health impacts from operation of two new nuclear units on occupational health 

and members of the public at the Red 2 site would be similar to those evaluated in Section 5.8 

for the STP site. Occupational health impacts to workers (e.g., falls, electric shock or exposure 

to other hazards) at the Red 2 site would likely be the same as those evaluated for workers at 

two new units at the STP site. Exposure to the public from water-borne etiological agents at the 

Red 2 site would be similar to the types of exposures evaluated in Section 5.8.1, and the 

operation of the new units at the alternative sites would not likely lead to an increase in waterborne diseases in the vicinity. Noise and EMF exposure would be monitored and controlled in 

accordance with applicable Occupational Safety and Health Administration (OSHA) regulations. 

Effects of EMF on human health would be controlled and minimized by conformance with 

National Electrical Safety Code (NESC) criteria and adherence to the standards for transmission 

systems regulated by the Public Utility Commission of Texas (PUCT). Nonradiological impacts 
Environmental Impacts of Alternatives 

February 2011 9-93 NUREG-1937 

of traffic associated with the operations workforce would be less than the impacts during 

building. Mitigation measures taken during building to improve traffic flow would also minimize 

impacts during operation of a new unit. 

The past and present activities in the geographic areas of interest that would have 

nonradiological impacts to the public or workers similar to those discussed for the Red 2 site 

include the Valley Power Plant and the wastewater treatment facility for the City of Bells. In the 

future, these facilities, the proposed Pattillo Branch Power Plant, transmission line systems, and 

future urbanization would have nonradiological impacts to the public and workers, and these 

impacts would be similar to those described for the proposed two new units at the Red 2 site. 

The review team is also aware of the potential climate changes that could affect human health; 

a recent compilation of the state of the knowledge in this area (GCRP 2009) has been 

considered in the preparation of this EIS. Projected changes in the climate for the region 

include an increase in average temperature and a decrease in precipitation, which may alter the 

presence of microorganisms and parasites in any reservoir that would be used. The review 

team did not identify anything that would alter its conclusion regarding the presence of 

etiological agents or change in the incidence of water-borne diseases. 

Summary 

Based on the information provided by STPNOC and the review team’s independent evaluation, 

the review team expects that nonradiological health impacts from building and operation of two 

new units at the Red 2 alternative site would be similar to the impacts evaluated for the STP 

site. While there are other past, present and future activities in the geographic area of interest 

that could affect nonradiological health in ways similar to the building and operation of two units 

at the Red 2 site, the impacts would be localized and managed through adherence to existing 

regulatory requirements. The review team concludes, therefore, that cumulative impacts would 

be SMALL. 

9.3.2.10 Radiological Impacts of Normal Operations 

The following impact analysis includes impacts from building activities and operations for two 

nuclear units at the Red 2 alternative site. The analysis also considers other past, present, and 

reasonably foreseeable future actions that impact radiological health, including other Federal 

and non-Federal projects listed in Table 9-8. As described in Section 9.3.2, Red 2 is a 

greenfield site; there are currently no nuclear facilities on the site. The geographic area of 

interest is the area within a 50-mi radius of the Red 2 site. There are no major facilities that 

result in regulated exposures to the public or biota within the 50-mi radius of the Red 2 site. 

However, there are likely to be hospitals and industrial facilities within 50 mi of the Red 2 site 

that use radioactive materials. 
Environmental Impacts of Alternatives 

NUREG-1937 9-94 February 2011 

The radiological impacts of building and operating the proposed two advanced boiling water 

reactor (ABWR) units at the Red 2 site include doses from direct radiation and liquid and 

gaseous radioactive effluents. These pathways would result in low doses to people and biota 

offsite that would be well below regulatory limits. These impacts are expected to be similar to 

those estimated for the STP site. The NRC staff concludes that the dose from direct radiation 

and effluents from hospitals and industrial facilities that use radioactive material would be an 

insignificant contribution to the cumulative impact around the Red 2 site. This conclusion is 

based on data from the radiological environmental monitoring programs conducted around 

currently operating nuclear power plants. 

Based on the information provided by STPNOC and the NRC staff's independent analysis, the 

NRC staff concludes that the cumulative radiological impacts from building and operating the 

two proposed ABWRs and other existing and planned projects and actions in the geographic 

area of interest around the Red 2 site would be SMALL. 

9.3.2.11 Postulated Accidents 

The following impact analysis includes radiological impacts from postulated accidents from 

operations for two nuclear units at the Red 2 alternative site. The analysis also considers other 

past, present, and reasonably foreseeable future actions that impact radiological health from 

postulated accidents, including other Federal and non-Federal projects and those projects listed 

in Table 9-8. As described in Section 9.3.2, the Red 2 site is a greenfield site; there are 

currently no nuclear facilities on the site. The geographic area of interest considers all existing 

and proposed nuclear power plants that have the potential to increase the probability-weighted 

consequences (i.e., risks) from a severe accident at any location within 50 mi of the Red 2 site. 

There are no existing or proposed reactors that have the potential to increase the probabilityweighted consequences (i.e., risks) from a severe accident at any location within 50 mi of the 

Red 2 Site. 

As described in Section 5.11.1, the NRC staff concludes that the environmental consequences 

of design basis accidents (DBAs) at the STP site would be minimal for ABWRs. DBAs are 

addressed specifically to demonstrate that a reactor design is robust enough to meet NRC 

safety criteria. The ABWR design is independent of site conditions, and the meteorology of the 

Red 2 and STP sites are similar; therefore, the NRC staff concludes that the environmental 

consequences of DBAs at the Red 2 site would be minimal. 

Because the meteorology, population distribution, and land use for the Red 2 alternative site are 

expected to be similar to the proposed STP site, risks from a severe accident for an ABWR 

reactor located at the Red 2 alternative site are expected to be similar to those analyzed for the 

proposed STP site. These risks for the proposed STP site are presented in Tables 5-18 and 

5-19 and are well below the median value for current-generation reactors. In addition, estimates 

of average individual early fatality and latent cancer fatality risks are well below the 
Environmental Impacts of Alternatives 

February 2011 9-95 NUREG-1937 

Commission’s safety goals (51 FR 30028). On this basis, the NRC staff concludes that the 

cumulative risks of severe accidents at any location within 50 mi of the Red 2 alternative site 

would be SMALL. 

9.3.3 Allens Creek 

This section covers the review team’s evaluation of the potential environmental impacts of siting 

a new two-unit nuclear power plant at the Allens Creek site in southeastern Texas. The site is 

located within a rural area of Austin County approximately 4 mi north of Wallis and 7 mi 

southeast of Sealy. Allens Creek is a greenfield site that was set aside for a nuclear power 

plant and cooling reservoir in the early 1970s in a proposal by the Houston Lighting and Power 

Company. Although the project was subsequently cancelled, a Final Environmental Statement 

for the proposed nuclear power plant was issued by the United States Atomic Energy 

Commission (AEC 1974). When appropriate, this report is used as a resource in the evaluation 

of Allens Creek as an alternative site. The majority of the site is currently owned by the City of 

Houston and the Brazos River Authority NRG Energy Inc. still owns 1722 ac of the site which 

would encompass the location of the power block, related facilities, and switchyard for siting 

new nuclear units (STPNOC 2010a). 

The following sections include a cumulative impact assessment conducted for each major 

resource area. The specific resources and components that could be affected by the 

incremental effects of the proposed action if implemented at the Allens Creek site and other 

actions in the same geographic area were considered. This assessment includes the impacts of 

NRC-authorized construction and operations and impacts of preconstruction activities. Also 

included in the assessment are other past, present, and reasonably foreseeable future Federal, 

non-Federal, and private actions that could have meaningful cumulative impacts when 

considered together with the proposed action if implemented at the Allens Creek site. Other 

actions and projects considered in this cumulative impact analysis are described in Table 9-12. 

Water for cooling and other plant uses would be from the Allens Creek Reservoir as currently 

proposed by the BRA. If the BRA reservoir is not constructed, a smaller reservoir at the same 

location would be constructed as part of the nuclear power plant project. The analysis of 

cumulative impacts for the Allens Creek site discussed below assumes the Allens Creek 

Reservoir is constructed by the BRA. Impacts associated with a smaller reservoir would be less 

than those anticipated for the proposed reservoir and are therefore not considered separately. 

Because the STP site is approximately 60 mi from Allens Creek, it is beyond the geographic 

area of interest for all resource areas with the exception of accidents. The only other nuclear 

power plant currently operating in Texas is Comanche Peak. The Comanche Peak plant is 

more than 200 mi from Allens Creek and therefore is also not included in the cumulative impact 

analysis. The proposed nuclear power plant in Victoria County is approximately 95 mi from 

Allens Creek and therefore was only considered in the accident analysis. 
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NUREG-1937 9-96 February 2011 

Table 9-12. Past, Present, and Reasonably Foreseeable Future Projects and Other Actions 

Considered in the Allens Creek Alternative Site Cumulative Analysis 

Project Name Summary of Project Location Status 

Energy Projects 

W.A. Parish Electric 

Generating Station 

Nine-unit, 3653-MW coal- and 

gas-fired plant 

About 30 mi 

southeast of 

Allens Creek 

site 

Operational(a)

South Texas Project Two 1265 MW(e) Westinghouse 

pressurized water reactors 

About 60 mi 

south of Allens 

Creek site 

Operational. STPNOC 

submitted an application 

for renewal of the 

operating licenses for 

Units 1 and 2 in October 

2010. If granted, the 

operating licenses would 

be extended for 20 

years, or until 2047 for 

Unit 1 and 2048 for 

Unit 2.(b)

Victoria County 

Station 

One or more large-scale power 

reactors 

About 95 mi 

southwest of 

Allens Creek 

site 

Proposed. Exelon 

Generation submitted an 

application to NRC for 

an Early Site Permit in 

March 2010.(c)

Transportation Projects 

Highway construction Construction of a 11.9-mi new 

location, four-lane, controlled 

access toll road from United 

States Highway (US) 290 to State 

Highway (SH) 249 in 

Harris County, Texas 

Approx 40 mi 

from Allens 

Creek site 

Proposed. Final EIS 

issued June 2009.(d)

Parks and Nature Preserve Facilities 

Texas Independence 

Trail 

Driving route within the Texas 

Independence Trail region 

Throughout the 

region near site 

Development likely 

limited at specific points 

along the trail(e)

Stephen F. Austin 

State Historical Park 

Activities include picnicking, 

camping, fishing, hiking, and 

nature and historical tours 

About 10 mi 

north of Allens 

Creek site 

Development likely 

limited within this park(f)

Attwater Prairie 

Chicken National 

Wildlife Refuge 

Home to one of the last 

populations of the critically 

endangered Attwater's prairiechicken 

Closest parcel 

of land is 5 mi 

west of Allens 

Creek site 

Development likely 

limited within this 

refuge(g)
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February 2011 9-97 NUREG-1937 

Table 9-12. (contd)

Project Name Summary of Project Location Status 

Brazos Bend State 

Park 

Activities include camping, 

picnicking, hiking, biking, 

equestrian, and fishing at six lakes 

About 20 mi 

southeast of 

Allens Creek 

site 

Development likely 

limited within this park(h)

Other Actions/Projects 

Allens Creek 

Reservoir 

9500-ac municipal water supply 

reservoir on Allens Creek 

proposed by Brazos River 

Authority 

At the Allens 

Creek site 

Proposed. Construction 

is expected to begin by 

2018.(i)

US Steel Tubular 

Products Inc. – 

Bellville Operations 

Division 

Line pipe and tubular goods 

manufacture 

About 20 mi 

northwest of 

Allens Creek 

site 

Operational(j)

Hudson Products 

Corporation 

Design and manufacture aircooled heat exchanger equipment 

to serve the oil, gas and 

petrochemical processing 

industries 

About 10 mi 

southeast of 

Allens Creek 

site 

Operational(k)

Frito Lay – Rosenberg 

Facility 

Food manufacturer About 20 mi 

southeast of 

Allens Creek 

site 

Operational(l)

Acme Brick, San 

Felipe Plant, Sealy 

Brick and structural clay tile 

manufacture 

About 10 mi 

north-northwest 

of Allens Creek 

site 

Operational(m)

Waste Water 

Treatment Plants 

Numerous plants Within 30 mi 

radius of site 

Operational 

Future Urbanization Construction of housing units and 

associated commercial buildings; 

roads (such as the I-69 Corridor 

project), bridges, and rail; 

construction of water- and/or 

wastewater- treatment and 

distribution facilities and 

associated pipelines, as described 

in local land-use planning 

documents. 

Throughout 

region 

Construction would 

occur in the future, as 

described in state and 

local land-use planning 

documents(n)
Environmental Impacts of Alternatives 

NUREG-1937 9-98 February 2011 

Table 9-12. (contd) 

Project Name Summary of Project Location Status 

Various hospitals and 

industrial facilities that 

use radioactive 

materials 

Medical and other isotopes Within 50 mi Operational in nearby 

cities and towns 

(a) Source: EPA 2009l 

(b) Source: STPNOC 2010c 

(c) Source: Exelon 2010 

(d) Source: USDOT 2009 

(e) Source: STPNOC 2009a 

(f) Source: TPWD 2009n 

(g) Source: STPNOC 2009a 

(h) Source: TPWD 2009o 

(i) Source: Brazos River Authority 2010 

(j) Source: USS 2009 

(k) Source: Hudson Products 2009 

(l) Source: EPA 2009m 

(m) Source: EPA 2009n 

(n) Source: TxDOT 2010 

9.3.3.1 Land Use 

The following impact analysis includes impacts from building activities and operations. The 

analysis also considers other past, present, and reasonably foreseeable future actions that 

impact land use, including other Federal and non-Federal projects and those projects listed in 

Table 9-12. For this analysis, the geographic area of interest for considering cumulative 

impacts is the 10-mi region surrounding the Allens Creek site. This area of interest was 

selected to include the primary communities (e.g., Sealy) that would be affected by the 

proposed project if it were located at the Allens Creek site. Figure 9-9 shows the location of the 

Allens Creek site and surrounding communities. 

The Allens Creek site is a greenfield site located in an unincorporated area of Austin County, 

Texas, 4.4 mi north of Wallis and 7.3 mi southeast of Sealy (STPNOC 2010a). There is no 

current zoning applicable to the site. 

In 1973, Houston Lighting and Power applied to the NRC for construction permits for a new, 

two-unit nuclear power plant at the site. The application was ultimately withdrawn in 1982 

(HMRC 2009). The City of Houston and the Brazos River Authority later acquired the land for a 

water storage reservoir to be built on Allens Creek, a tributary of the Brazos River. Currently, 

the Brazos River Authority plans to construct a 9500-ac reservoir at the site to serve the future 

water needs of the City of Houston and surrounding communities. Construction is expected to 

begin in 2018 (Brazos 2009). This analysis assumes the reservoir would be a source of cooling 

water for new nuclear units sited at Allens Creek. 
Environmental Impacts of Alternatives 

February 2011 9-99 NUREG-1937 

Figure 9-9. Allens Creek Alternative Site and 10-mi Radius
Environmental Impacts of Alternatives 

NUREG-1937 9-100 February 2011 

If the Brazos River Authority does not construct the planned reservoir, an alternative reservoir 

would be needed for plant cooling. Alternatively, water could potentially be withdrawn directly 

from the Brazos River. 

The land area affected by building two nuclear generating units at the Allens Creek site would 

be approximately 800 ac for the main power plant site and up to 9500 ac for the new, multi-use 

reservoir (STPNOC 2010a). Land-use impacts would also occur to divert water to the plant and 

return discharge water to Allens Creek and for road and rail access. 

In 1973, the majority of the Allens Creek site was cleared of the native hardwood vegetation, 

and an extensive system of drainage ditches was constructed which allowed much of the area 

to be used to farm row crops. Much of the Allens Creek site is open cropland and pasture, but 

hardwood riparian areas and bluff forests exist along the Brazos River and Allens Creek. Major 

crops grown in the area include corn, cotton, sorghum, and hay. Uncleared and partially 

cleared land is used to graze cattle (STPNOC 2010a). 

The Allens Creek site is not in the geographic area covered by the TCMP (TCMP 2009); 

therefore, the CZMA does not apply to this site. 

Three new transmission line corridors would likely be needed to connect the Allens Creek site to 

the three closest 345-kV lines in the area. The Allens Creek site is approximately 20 mi west of 

the 345-kV connection at the O’Brien Substation, 30 mi northwest of the 345-kV line between 

W.A. Parish power plant and the Hill Substation, and 35 mi northeast of the 345-kV line between 

Holman and Hill substations. The total combined distance for new corridors would be 

approximately 85 mi. Farmlands that would become part of a corridor could generally continue 

to be farmed. Based on 85 mi of corridor and a 200-ft corridor width, installation of new 

transmission corridors would impact approximately 2000 ac (STPNOC 2010a). 

Future urbanization in the geographic area of interest and GCC could contribute to decreases in 

open lands, wetlands, and forested areas. Urbanization in the vicinity of the Allens Creek site 

would alter important attributes of land use. Urbanization would reduce natural vegetation and 

open space, resulting in an overall decline in the extent and connectivity of wetlands, forests, 

and wildlife habitat. GCC could decrease precipitation, causing more frequent droughts when 

combined with increased evaporation in the geographic area of interest for the Allens Creek site 

(GCRP 2009). Reduced water supply and increased temperatures could reduce crop yields and 

livestock productivity (GCRP 2009), which might change portions of agricultural and ranching 

land uses in the area of interest. However, existing parks, reserves, and managed areas would 

help preserve open lands, wetlands, and forested areas to the extent that they are not adversely 

affected by droughts. Future urbanization trends and direct changes resulting from GCC could 

noticeably alter land uses in the geographic area of interest. 
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February 2011 9-101 NUREG-1937 

Based on the information provided by STPNOC and the review team’s independent review, the 

review team concludes that the cumulative land-use impacts of constructing and operating two 

new nuclear generating units at the Allens Creek site would be MODERATE. This conclusion 

reflects the substantial amount of land (800 ac for the main power plant site; up to 9500 ac for 

the new, multi-use reservoir; and approximately 2000 ac for transmission corridors) that would 

be needed if the proposed reservoir is built and two new nuclear units were sited at the Allens 

Creek site, and land use changes from increased urbanization and potential effects of GCC. 

Building and operating two new nuclear units at the Allens Creek site would be a significant 

contributor to the MODERATE impact. 

9.3.3.2 Water Use and Quality 

The following impact analysis includes impacts from building activities and operations. 

The analysis also considers other past, present, and reasonably foreseeable future actions 

that impact water use and quality including other Federal and non-Federal projects listed in 

Table 9-12. The Allens Creek site is located in rural Austin County in southeastern Texas. 

Development of this site for two nuclear units would require the building of a water reservoir on 

the Allens Creek site supplied with water from the Brazos River. 

Geographic areas of interest are the surface water in the drainage basin of the Brazos River 

upstream and downstream of the likely intake and outfall structures and the Allens Creek 

drainage, and for groundwater the aquifers upgradient and downgradient of the site. These 

regions are of interest because they represent the water resource potentially affected by the 

proposed project if it were located at the Allens Creek site. 

As stated in Section 2.3.2, water use in Texas is regulated by the Texas Water Code. As 

established by Texas Water Code, surface water belongs to the State of Texas (Texas Water 

Code, Chapter 11, Section 11.021). The right to use surface waters of the State of Texas can 

be acquired in accordance with the provisions of the Texas Water Code, Chapter 11. In Texas, 

surface water is a commodity. Since the Brazos River Basin is currently heavily appropriated, 

future water users in this basin would likely only obtain surface water by purchasing or leasing 

existing appropriations. Regarding groundwater, Texas law has allowed landowners to pump 

the water beneath their property without consideration of impacts to adjacent property owners 

(NRC 2009). However, Chapter 36 of Texas Water Code authorized groundwater conservation 

districts to help conserve groundwater supplies. Chapter 36, Section 36.002, Ownership of 

Groundwater, states that ownership rights are recognized and that nothing in the code shall 

deprive or divest the landowners of their groundwater ownership rights, except as those rights 

may be limited or altered by rules promulgated by a district. Thus, groundwater conservation 

districts with their local constituency offer groundwater management options (NRC 2009). 

Existing projects in the State have appropriations to use water for their requirements. The 

review team expects that future projects, including the proposed units, if they were to be built 
Environmental Impacts of Alternatives 

NUREG-1937 9-102 February 2011 

and operated at the Allens Creek site, would operate within the limits of these existing surface 

water and groundwater appropriations. 

As stated in Section 7.2.1, the GCRP has compiled the state of knowledge in climate change. 

This compilation has been considered in the preparation of this EIS. The projections for 

changes in temperature, precipitation, droughts, and increasing reliance on aquifers within the 

Brazos River Basin are similar to those in the Colorado River Basin (GCRP 2009). Such 

changes in climate would result in adaptations to both surface water and groundwater 

management practices and policies that are unknown at this time. 

There are currently 1368 water rights owners in the Brazos River Basin, with total water rights of 

4,350,000 ac-ft/yr that are categorized as industrial, irrigation, or mining users (TCEQ 2009a). 

According to TCEQ’s water availability maps, unappropriated flows in the Lower Brazos River 

Basin for a perpetual water rights permit are available 0 to 50 percent of the time in Austin 

County (TCEQ 2009b). The water availability maps do not show the quantity of available water 

for a new appropriation (TCEQ 2009b). 

The Texas Water Development Board, in the 2007 State Water Plan, has estimated that 

groundwater supplies of more than 1.6 million ac-ft/yr would be available from 2010-2060 in the 

Gulf Coast Aquifer that is shared by 54 counties and approximately 100,000 ac-ft/yr in the 

Brazos River Alluvium Aquifer that is shared by 13 counties (TWDB 2006a). The Bluebonnet 

Groundwater Conservation District (BGCD) has estimated the amount of usable groundwater in 

the district as approximately 107,289 ac-ft/yr based on 2001 Region H and Region G Water 

Plans (BGCD 2004). The estimated groundwater availability of the Gulf Coast and Brazos River 

Alluvium aquifers within the district are approximately 53,259 and 10,307 ac-ft/yr (BGCD 2004). 

The TWDB reported that wells in the Gulf Coast Aquifer support pumping rates from less than 

100 to more than 3000 gpm and those in the Brazos River Alluvium Aquifer support pumping 

rates of 250 to 500 gpm. The estimated groundwater use within the district is approximately 

23,214 ac-ft/yr (BGCD 2004). 

Building Impacts

The review team assumed that no surface water would be used to build the proposed units at 

the Allens Creek site so there would be no impact on surface water use. This assumption is 

consistent with the analysis done for the STP site and the other alternative sites. 

The impacts on surface water quality from building potential units at the Allens Creek alternative 

site would be limited to stormwater runoff that may enter nearby streams and rivers. 

Additionally, treated sanitary wastewater may be discharged to these streams and rivers. 

Building impacts would be limited by the duration of these activities, and therefore, would be 

temporary. The State of Texas prohibits the unauthorized discharge of waste into or adjacent to 

water in the state (Texas Water Code, Chapter 26, Section 26.121). The discharge of waste 
Environmental Impacts of Alternatives 

February 2011 9-103 NUREG-1937 

may be authorized under a general or individual permit (Texas Water Code, Chapter 26). 

These permits may require an SWPPP that includes BMPs appropriate for the site (TCEQ 2003; 

STPNOC 2010a). Implementation of BMPs should minimize impacts to wetlands and surfacewater bodies near the Allens Creek alternative site. Therefore, the water quality impacts on 

wetlands and water bodies near the Allens Creek alternative site related to building the 

proposed new units would be temporary and minimal. 

The review team assumes that the groundwater use for building activities at the Allens Creek 

site would be identical to the proposed groundwater use for the STP site (STPNOC 2009a) 

because the site would utilize units similar to those proposed for the STP site and the building 

activities would also be similar. Monthly normalized groundwater use for the STP site ranges up 

to 491 gpm (792 ac-ft/yr) (see Table 3-4). STPNOC stated that groundwater would be used for 

potable and sanitary use, concrete batch plant operation, concrete curing, dust suppression and 

cleaning, placement of engineered backfill, and piping hydrotests and flushing (STPNOC 

2010a). 

The Allens Creek alternative site is located in Texas GMA 14 and the BGCD. Since publication 

of the draft EIS, GMA 14 adopted desired future conditions for its aquifers including the Gulf 

Coast and Brazos River Alluvium aquifers; however, managed available groundwater reports for 

the aquifers have not been issued (TWDB 2010c, BGCD 2010). STPNOC has suggested the 

Gulf Coast and the Brazos River Alluvium aquifers as the potential sources of groundwater. 

Based on the available information, the review team determined that the groundwater that would 

be used to build proposed units at the Allens Creek alternative site would be less than 2 percent 

of the available groundwater from the Gulf Coast and the Brazos River Alluvium aquifers within 

the BGCD. Based on standard practice, the review team concluded that the drawdown from 

pumping the aquifers could be minimized during building-related groundwater pumping using an 

appropriately designed well system. The review team concluded, based on available 

information, that the impact of groundwater use for building related activities at the Allens Creek 

site would be minimal. 

The review team found that groundwater in the Gulf Coast Aquifer system is reported to be of 

good quality underlying Austin County (TWDB 2006a). Levels of total dissolved solids (TDS) in 

the Chicot, Evangeline, and Jasper Aquifers of the Gulf Coast Aquifer system are all shown as 

less than 1000 mg/L. The review team concludes that wells completed in the Gulf Coast Aquifer 

system should produce good quality groundwater. During building of any potential units at the 

Allens Creek alternative site, impacts to groundwater quality may occur from leaching of spilled 

effluents into the subsurface. BMPs would be in place during building activities and therefore 

the review team concluded that any spills would be quickly detected and remediated. In 

addition, impacts would be limited by the duration of these activities, and therefore, would be 

temporary. Because any spills would be quickly detected and remediated and the activities 
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NUREG-1937 9-104 February 2011 

causing the spill would be temporary, the review team concluded that the groundwater-quality 

impacts from building at the Allens Creek site would be minimal. 

Operational Impacts

STPNOC estimated that a two-unit plant, operated at the Allens Creek alternative site using a 

closed-cycle cooling system that would employ a cooling water reservoir would consume a 

maximum of 50,000 ac-ft of water per year. STPNOC identified the Brazos River as the likely 

source of cooling water at the Allens Creek alternative site. STPNOC currently does not own 

the necessary water rights. STPNOC would acquire existing Brazos River water rights that are 

currently being used for industrial, irrigation, and mining use. Based on the total water rights 

currently issued for the Brazos River Basin, STPNOC would need to acquire a minimum of 

1.1 percent of these water rights (STPNOC 2010a). 

At the Allens Creek site, the BRA has plans to create a 9500-ac reservoir for multiple uses, 

including water supply. The proposed reservoir would supply water to the City of Houston and a 

portion of the water would be owned by the BRA. Currently, construction of the reservoir is 

scheduled to begin in 2018 and be completed by 2030. STPNOC would need to acquire 

sufficient water rights in the proposed reservoir and would need the building of the reservoir to 

begin earlier to support operation of potential units at the Allens Creek alternative site 

(STPNOC 2010a). 

According to TCEQ staff, the water rights for the proposed reservoir at Allens Creek have 

already been permitted (NRC 2009). Therefore, the aggregation of these water rights that 

STPNOC would need to acquire at the potential plant site would not be of concern. However, 

the review team determined that the reservoir’s water rights are currently allocated for municipal 

use. The acquisition of these water rights for potential new nuclear units at the Allens Creek 

alternative site could displace municipal users. The Allens Creek site is located in Austin 

County, which is part of Region H. The projected water demand for municipal users in 

Region H for 2010 is 897,600 ac-ft and is estimated to grow to 1,480,300 ac-ft in 2060 

(TWDB 2006a). The needed water supply for municipal users in Region H for 2010 is 

69,700 ac-ft and projected to grow to 518,600 ac-ft in 2060. The proposed reservoir at Allens 

Creek is estimated to supply 97,400 ac-ft. The cooling water demand of approximately 

50,000 ac-ft/yr for potential units at the Allens Creek alternate site would result in an increased 

need for municipal uses in Region H. The review team determined, therefore, that the surface 

water use impacts of operations at the Allens Creek site would be noticeable but not 

destabilizing. 

During the operation of a potential plant at the Allens Creek alternative site, impacts to surface 

water quality could result from stormwater runoff, discharges of treated sanitary and other 

wastewater, blowdown from service water cooling towers, and periodic discharges from the 

cooling water reservoir into the Brazos River. As mentioned above, the State of Texas may 
Environmental Impacts of Alternatives 

February 2011 9-105 NUREG-1937 

require STPNOC to obtain a general or individual permit for the discharge of stormwater (Texas 

Water Code, Chapter 26). These permits may require an SWPPP that includes BMPs 

appropriate for the site (TCEQ 2001; STPNOC 2010a). Any discharges of sanitary and other 

wastewaters and cooling water reservoir discharges would be controlled by the State of Texas 

under a TPDES permit. The State of Texas limits the quantity and quality of discharges to 

surface water bodies while accounting for concurrent discharge and quality conditions within the 

surface water body. These permit conditions would also account for designated uses of the 

receiving surface water body. The review team expects that the conditions placed on 

operations of any potential new nuclear units at the Allens Creek site would be similar to those 

currently placed on the existing facilities at the STP site (see Section 5.2.3.1). Therefore, the 

review team concluded that the operational impact on surface water quality of the Brazos River 

would be minimal because the discharge quantity and quality would be controlled. 

The proposed Units 3 and 4 would use approximately 975 gpm (1572 ac-ft/yr) of groundwater 

during normal operations and approximately 3434 gpm (5538 ac-ft/yr) during maximum demand 

conditions (STPNOC 2010a). STPNOC stated that the expected groundwater use for Units 3 

and 4 are assumed to also apply to alternative sites (STPNOC 2009a). However, for maximum 

operation demand periods, STPNOC assumes that a temporary increase in the rate of surface 

water use would be available. 

The review team determined that the groundwater use at the Allens Creek alternative site during 

operations would not be unreasonable because the alternative site would utilize units similar to 

those proposed for the STP site. 

As stated above, since publication of the draft EIS desired future conditions for the Gulf Coast 

and Brazos River Alluvium aquifers were adopted by GMA 14; however,estimates of the 

managed available groundwater have not been adopted (TWDB 2010c,BGCD 2010). The 

BGCD has estimated the amount of usable groundwater in the district as approximately 

107,289 ac-ft/yr based on 2001 Region H and Region G Water Plans (BGCD 2004). The 

estimated groundwater availability of the Gulf Coast and Brazos River Alluvium aquifers within 

the district are approximately 53,259 and 10,307 ac-ft/yr (BGCD 2004). Based on the available 

information, the review team determined that the groundwater use for the operation of proposed 

units at the Allens Creek alternative site would be 2.5 percent of the available groundwater from 

the Gulf Coast and the Brazos River Alluvium aquifers within the BGCD. During operation of 

any potential plant at the Allens Creek alternative site, some drawdown of the Brazos River 

Alluvium and the Gulf Coast Aquifers could be expected. Based on standard hydrogeologic 

practice, the amount of drawdown in the aquifers from groundwater pumping during operation 

could be limited by installing multiple, appropriately-spaced wells because groundwater would 

be withdrawn from a large area resulting in smaller drawdown. Therefore, because 

groundwater use would be a relatively small fraction of the available groundwater, there is 

available capacity (BGCD 2004), and drawdown could be controlled, the review team concluded 

that the impact of operational groundwater use at the Allens Creek site would be minimal. 
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NUREG-1937 9-106 February 2011 

During the operation of a potential plant at the Allens Creek alternative site, impacts to 

groundwater quality could result from potential spills. Spills that might affect the quality of 

groundwater would be prevented and mitigated by BMPs. As noted above, groundwater in the 

Gulf Coast Aquifer system underlying Austin County is of good quality (TWDB 2006a). Because 

any spills would be quickly detected and remediated through the use of BMPs and no intentional 

discharge to groundwater should occur, the review team concludes that the groundwater-quality 

impacts from operations at the Allens Creek site would be minimal. 

Cumulative Impacts

In addition to water use and water quality impacts from building and operations activities, 

cumulative analysis considers past, present, and reasonably foreseeable future actions that 

impact the same environmental resources. For the cumulative analysis of impacts on surface 

water, the geographic area of interest for the Allens Creek site is considered to be the drainage 

basin of the Brazos River upstream and downstream of the intake and outfall structures 

including the Allens Creek drainage because this is the surface water resource that would be 

affected by the proposed project if it were located at the Allens Creek site. Key actions that 

have past, present and future potential impacts to water supply and water quality in the Brazos 

River Basin include the existing W.A. Parish Electric Generating Station and numerous sewage 

treatment facilities. 

Cumulative Water Use

The only surface-water-use impacts of building and operating a nuclear power plant at this site 

are the demands occurring during operation. The projected consumptive surface water use of 

the two units is expected to be about 50,000 ac-ft/yr or less than 1.1 percent of the total water 

rights of 4,350,000 ac-ft/yr currently held by 1368 water rights owners in the Brazos River Basin. 

Past and present water withdrawals, reflected by the water rights held in the Brazos River 

Basin, have used the waters of the river. Currently, unappropriated flows in the Lower Brazos 

River Basin are available for a perpetual water rights permit less than half of the time during a 

typical year. The surface water use for the proposed units, if they were to be built at the Allens 

Creek site, is already granted by TCEQ and held by the City of Houston and the Brazos River 

Authority. Reasonably foreseeable future actions in the Brazos River Basin, primarily the 

predicted estimated population growth of 77 percent between 2010 and 2060 (TWDB 2006a), 

could noticeably alter, but due to water management strategies, not destabilize, the surface 

water resource. Water management strategies could include conservation, wastewater reuse, 

system operation of the Brazos River Authority reservoirs, desalination, reservoir augmentation, 

and new reservoirs, among other strategies (TWDB 2006c). The impacts of other projects listed 

in Table 9-12 would have little or no impact on surface water use. 

Groundwater-use impacts of building and operating a nuclear power plant at this site are 

characterized by the groundwater demand at the STP site, and those use levels are 491 gpm 

(792 ac-ft/yr) during building activities, a normal operation demand of 975 gpm (1572 ac-ft/yr), 
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February 2011 9-107 NUREG-1937 

and a maximum operation demand of 3434 gpm (5538 ac-ft/yr) (STPNOC 2010a). However, for 

maximum operation demand periods, STPNOC assumes that a temporary increase in the rate 

of surface water use would be available. During building and normal operation of two nuclear 

units at the Allens Creek site, the possibilities exist that STPNOC could (1) a new groundwater 

permit and associated wells, (2) access to existing groundwater production from wells in the 

vicinity of the plant, and (3) use of imported water primarily for potable use onsite 

(STPNOC 2009a). With regard to the groundwater resource available to all past, present, and 

future projects, the BGCD (2004) estimates groundwater availability of 63,566 ac-ft/yr and 

groundwater use of 23,214 ac-ft/yr within the BGCD for the Gulf Coast and Brazos River 

Alluvium aquifers. The review team concludes there is a net surplus of groundwater available 

within the BGCD. 

The review team is also aware of the potential for GCC affecting the water resources available 

for closed-cycle cooling and the impact of reactor operations on water resources for other users. 

The impact of GCC on regional water resources is not precisely known, however it may result in 

decreases in precipitation and increases in average temperature (GCRP 2009). Such changes 

could further stress regional water resources. However, the impacts related to GCC would be 

similar for all the alternative sites. 

Historically, the waters of the Brazos River Basin have been used extensively. The region has a 

planning, allocation, and development system in place to manage the use its limited surface 

water supplies. These efforts are described in the Regional and State Water Plans 

(TWDB 2006a, b, c). The operation of the proposed units at the Allens Creek site would result 

in noticeable but not destabilizing impact on surface water use in the region. Future growth 

would also result in noticeable but not destabilizing impact on surface water use in the region. 

Therefore, the review team concludes that cumulative impacts to surface water use would be 

MODERATE. However, building and operating the proposed plant at the Allens Creek site 

would not be a significant contributor to these water-use impacts because the water rights are 

already held by the City of Houston and the Brazos River Authority. 

As indicated above, groundwater would be used during the building and operation of two 

nuclear units at the Allens Creek site. Because alternatives are available to supplying the 

needed groundwater (i.e., new groundwater wells, acquired groundwater permits, and import of 

potable water), a potential reduction in new groundwater demand, and the available 

groundwater resource, the review team concludes there would not be a substantial impact to 

other nearby users of groundwater. As such, the review team concludes that cumulative 

impacts to groundwater use would be SMALL. The impacts of other projects listed in 

Table 9-12 would have little or no impact on surface water and groundwater use. 

Cumulative Water Quality

Point and nonpoint sources in the river basin have affected the water quality of the Brazos 

River. Water quality information presented above for the impacts of building and operating the 
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NUREG-1937 9-108 February 2011 

new units at the Allens Creek site would also apply to evaluation of cumulative impacts. The 

State of Texas may require an applicant to obtain a general or individual permit for discharge of 

stormwater (Texas Water Code, Chapter 26). These permits may require an SWPPP that 

includes BMPs appropriate for the site (TCEQ 2001, 2003; STPNOC 2010a). The State of 

Texas would also issue TPDES permits for the discharge of sanitary and other wastewaters, 

including blowdown from service water cooling towers and cooling water reservoir discharges, 

before operation of the units at the Allens Creek site. Effluent discharges through TPDESpermitted outfalls, such as those from the W.A. Parish Electric Generating Station and sewage 

treatment plants, are required to comply with the Clean Water Act. Such permits are designed 

to protect water quality. Therefore, the review team concluded that the cumulative impact on 

surface water quality of the receiving water body would be SMALL. The impacts of other 

projects listed in Table 9-12 would have little or no impact on surface water quality. 

The review team also concludes that with the implementation of BMPs, the impacts of 

groundwater quality from building and operating two new nuclear units at the Allens Creek site 

would likely be minimal. The individual impacts from other projects listed in Table 9-12 would 

have little or no impact on regional groundwater quality because of the local nature of 

groundwater withdrawals and their associated impacts. Therefore, the cumulative impact on 

groundwater quality would be SMALL. 

9.3.3.3 Terrestrial and Wetland Resources 

The following impact analysis includes impacts from building activities and operations. The 

analysis also considers other past, present, and reasonably foreseeable future actions that 

impact terrestrial and wetland resources, including other Federal and non-Federal projects listed 

in Table 9-12. For the analysis of terrestrial ecological impacts, the geographic area of interest 

is considered to be intersection of the Western Gulf Coastal Plains ecoregion with the Lower 

Brazos and San Bernard watersheds within Austin, Colorado, Wharton, Waller and Fort Bend 

Counties (Figure 9-10). This area is expected to encompass the ecologically relevant 

landscape features and species. 

Austin County is in the Coastal Prairie subprovince of the Gulf Coastal Plains ecoregion 

(UT 1996). The Coastal Prairie of Texas is a tallgrass prairie similar to the tallgrass prairie of 

the Great Plains (TPWD 2009a). Trees are uncommon except along streams and in oak mottes 

(i.e., groves) (UT 1996). Nearly 1000 plant species have been identified in the Coastal Prairie 

and it provides habitat for wintering waterfowl and spring neotropical migratory birds 

(TPWD 2009b). It is home to the Federally endangered Attwater’s prairie chicken 

(Tympanuchus cupido attwateri) and is the exclusive wintering ground of the whooping crane 

(Grus americana). Plants in this ecoregion include trees such as oak (Quercus spp.), elm 

(Ulmus spp.), mulberry (Morus sp.), cedar (Juniperus sp.) and pine (Pinus spp.); grasses such 

as bluestem (Andropogon sp.) and cordgrass (Spartina sp.). Almost all of the coastal prairies 

have been converted to cropland, rangeland, pasture, or urban uses. 
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February 2011 9-109 NUREG-1937 

Figure 9-10. Geographic Area for the Analysis of Cumulative Impacts to Terrestrial Resources 

Within the Western Gulf Coast Plains Ecoregion in the Lower Brazos and San 

Bernard watersheds within Austin, Colorado, Wharton, Waller, and Fort Bend 

Counties 
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NUREG-1937 9-110 February 2011 

The terrain at the Allens Creek site varies from rolling hills in the northern, western, and central 

sections to a nearly level coastal prairie in the south where site is located (STPNOC 2010a). 

Currently, the site is mostly flat, agricultural land used to farm row crops (primarily cotton, 

sorghum, corn, and soybeans) and graze cattle. Although much of the site has been disturbed 

for agriculture, the coastal prairie around the site exhibits wide expanses of open grassland 

fringed by stands of oak and elm. In 1973, the majority of the site was cleared of native 

hardwood vegetation, and an extensive system of drainage ditches was constructed to allow the 

area to be used for farming row crops. Uncleared and partially cleared land was used to graze 

cattle. The area is prone to flooding and is not considered appropriate for urban development. 

The total acreage for all temporary and permanent impacts would be 800 ac for the plant site, 

with 300 ac permanently affected (STPNOC 2010a). The proposed Allens Creek reservoir 

would be used for cooling water. The City of Houston and the BRA acquired part of this site for 

a proposed 9500-ac reservoir (STPNOC 2010a). For the purposes of this analysis, the review 

team assumes that the proposed reservoir would be built and functional before the two new 

nuclear power reactors would be built. General land uses and acreage estimates for areas 

permanently affected by building are presented in Table 9-13 (STPNOC 2010a). The plant site 

would be located on the bluff on the western side of the reservoir. No wetlands were identified 

within the footprint of the Allens Creek alternative site. 

Table 9-13. Estimated Acreages by Land Cover Classes for Approximately 300 ac of the 

800-ac Allens Creek Site. 

Land Cover Class Plant (ac)(a)

Bluff forest 75 

Grass 225 

Total 300 

Source: STPNOC 2010a. 

(a) Acreages are for areas permanently affected by 

building at the site. 

Ecologically important areas occurring near the Allens Creek site include the Attwater Prairie 

Chicken National Wildlife Refuge (NWR) (FWS 2009c) and two Ecologically Significant River 

and Stream Segments: the Brazos River and Mill Creek (TPWD 2010). The Attwater Prairie 

Chicken NWR contains one of the largest remnants of coastal prairie habitat in southeast Texas 

and provides habitat to the critically imperiled prairie chicken (in 1996 there were fewer than 

50 birds in the wild) (TPWD 2009g). The ecologically significant segment of the Brazos River 

extends from the confluence with the Gulf of Mexico upstream to Austin/Waller County and 

includes riparian conservation areas and rare live oak-water oak-pecan bottomlands 

(TPWD 2010). Special habitat features associated with Mill Creek include the rare 

gammagrass-switchgrass (Tripsacum dactyloides – Panicum virgatum) bottomland tallgrass 

prairie (TPWD 2010). 
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February 2011 9-111 NUREG-1937 

Important Species 

Because of changing land-use practices over the years that have reduced upland game species 

habitat in the Texas Parks and Wildlife Oak-Prairie Wildlife District, the occurrence of game 

species has been reduced (STPNOC 2009a). This district emcompasses 26 counties in 

southeastern Texas; Austin County is in the northcentral section (TPWD 2009e). The demise of 

the small farmer, whose farms in the northern district provided excellent habitat for doves and 

quail, and the conversion of native pastures to improved grasses to enhance cattle production 

have combined to greatly reduce the quail population. Dove hunting is still popular in many 

parts of the Oak-Prairie Wildlife District, although the number of available birds is tied to food 

supply. There is a hunting season for white-tailed deer and quail in Austin County. Finally, the 

Oak-Prairie Wildlife District has two species of turkeys: the eastern turkey (stocked in the 

eastern tier of counties) and the Rio Grand turkey (Meleagris gallopavo intermedia), which is 

found in many western counties. Turkeys are usually found along the major creek and river 

drainages. Most counties do not support a large number of birds (STPNOC 2009a). 

The Allens Creek site is within the Central Flyway of Texas (STPNOC 2009a) and would 

provide habitat for rest and forage opportunities during migration. There are two birding areas 

in the vicinity of the Allens Creek site that support migratory birds: 

• The Washington-on-the-Brazos State Historic Park (within the southern portion of the 

Prairies and Pineywoods Wildlife Trail West; more than 20 mi north of Allens Creek in 

Washington county), where migratory birds have been observed along the Brazos River 

(vireos, warblers, tanagers, orioles and neotropical migrants including warblers); and 

• Chapel Hill/Brazos River Valley Trail (east of SH 36 near Hempstead, between 10 and 15 mi 

north of the Allens Creek site) (STPNOC 2009a), where “[s]pring and fall migrations release 

a river of neotropical birds through this area.” 

Up to 10 bat species living in eastern Texas, can occur in Austin County (Davis and Schmidly, 

1994; STPNOC 2009a). Some are mostly year-round residents (i.e., non-migratory), such as the 

big brown bat (Eptesicus fuscus), the eastern pipistrelle (Perimyotis subflavus), evening bat 

(Nycticeius humeralis), and Seminole bat (Lasiurus seminolus). Migratory bats that could occur 

at the site include the hoary bat (L. cinereus), the silver-haired bat (Lasionycteris noctivagans), 

the eastern red bat (Lasiurus borealis), the big free-tailed bat (Nyctinomops macrotis), the 

northern yellow bat (L. intermedius), and the Mexican free-tailed bat (Tadarida brasiliensis). The 

Mexican free-tailed bat can be either migratory or non-migratory depending on where it resides; 

the migratory status of bats occurring in Austin County is currently unknown (STPNOC 2009a). 

No site specific surveys have been conducted for threatened and endangered species at the 

Allens Creek site or along likely transmission line corridors. The likely transmission line 

corridors could potentially cross into three adjacent counties: Fort Bend, Colorado, and 

Wharton. Table 9-14 lists the Federally and State threatened and endangered species (FWS 
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NUREG-1937 9-112 February 2011 

2009a; TPWD 2009f). No areas designated as critical habitat for Federally-listed species exist 

in Austin County or in the three counties (i.e., Fort Bend, Colorado, and Wharton) where 

transmission lines may be routed (STPNOC 2009a). 

Table 9-14. List of Federal and State Threatened and Endangered Species in Austin, Fort 

Bend, Colorado, and Wharton Counties, Texas 

Group Common Name Scientific Name 

Federal 

Status

State 

Status County 

Plants Texas prairie dawn-flower Hymenoxys texana E E Fort Bend 

Amphibians Houston toad Bufo houstonensis E E Austin, Fort Bend, 

Colorado 

Reptiles Alligator snapping turtle Macrochelys temminckii T Austin, Fort Bend 

Smooth green snake Liochlorophis vernalis T Austin 

Texas horned lizard Phrynosoma cornutum T Austin, Fort Bend, 

Wharton, Colorado

Timber/Canebrake 

rattlesnake 

Crotalus horridus T Austin, Fort Bend, 

Wharton, Colorado

Birds American Peregrine 

Falcon 

Falco peregrinus 

anatum 

 T Austin, Fort Bend, 

Wharton, Colorado

Attwater's Greater PrairieChicken 

Tympanuchus cupido 

attwateri 

E E Austin, Fort Bend, 

Wharton, Colorado

Bald Eagle Haliaeetus 

leucocephalus 

 T Austin, Fort Bend, 

Wharton, Colorado

Interior Least Tern Sternula antillarum 

athalassos 

 E Austin, Fort Bend, 

Wharton, Colorado

White-faced ibis Plegadis chihi T Austin, Fort Bend, 

Wharton, Colorado

White-tailed hawk Buteo albicaudatus T Austin, Fort Bend, 

Wharton, Colorado

Whooping crane Grus americana E E Austin, Fort Bend, 

Wharton, Colorado

Wood Stork Mycteria americana T Austin, Fort Bend, 

Wharton, Colorado

Mammals Louisiana black bear Ursus americanus 

luteolus 

T T Austin, Fort Bend, 

Wharton, Colorado

Red wolf Canis rufus E Austin, Fort Bend, 

Wharton, Colorado

Sources: FWS 2009a; TPWD 2009f 

T = threatened; E = endangered; T/SA = proposed similarity of appearance to a threatened taxon 

Texas prairie dawn-flower

The Texas prairie dawn-flower (Hymenoxys texana) is a Federally and State-listed endangered 

species and is found in Fort Bend County (FWS 2009a; TPWD 2009f). The plant is a delicate 
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February 2011 9-113 NUREG-1937 

annual forb found in poorly drained, sparsely vegetated areas at the bases of small mounds in 

open grassland or in almost barren areas (NatureServe 2009b). They are found in slightly 

saline soils and are sometimes associated with other Texas Gulf Coast Plain endemics such as 

Texas windmill-grass (Chloris texensis) and Houston machaeranthera (Machaeranthera aurea). 

Houston toad

The Houston toad (Bufo houstonensis) is a Federally and State-listed endangered species and 

is found in Austin, Fort Bend, and Colorado Counties (FWS 2009a; TPWD 2009f). It lives 

primarily on land and burrows into sand for protection from cold weather in the winter and from 

hot, dry conditions in the summer. The toads are found in areas with loose, deep sand 

supporting woodland savannah and in proximity to still or flowing waters for breeding (TPWD 

2009g). The toads have been recorded in Austin County and in the lower Brazos River 

watershed (NatureServe 2009b). 

Alligator snapping turtle

The alligator snapping turtle (Macrochelys temminckii) is a State-listed threatened species and 

is found in Austin and Fort Bend Counties (TPWD 2009f). It is found in slow-moving, deep 

water of rivers, sloughs, oxbows, and canals or lakes associated with rivers; and also in 

swamps, ponds near rivers, and shallow creeks that are tributary to occupied rivers 

(NatureServe 2009b). It usually occurs in water with mud bottoms and abundant aquatic 

vegetation; it may migrate several miles along rivers (TPWD 2009g). Turtles are rarely found 

out of the water except when nesting. 

Smooth green snake

The smooth green snake (Liochlorophis vernalis) is a State-listed threatened species (TPWD 

2009f) and is found in Austin County. Habitats include meadows, grassy marshes, moist grassy 

fields at forest edges, mountain shrublands, stream borders, bogs, open moist woodland, 

abandoned farmland, and vacant lots (NatureServe 2009b). They have also been found 

hibernating in abandoned ant mounds. The snake may be extirpated in Austin County, but has 

recently been recorded in the Lower Brazos River watershed. 

Texas horned lizard 

The Texas horned lizard (Phrynosoma cornutum) is a State-listed threatened species and is 

found in Austin, Fort Bend, Colorado, and Wharton Counties (TPWD 2009f). It can be found in 

arid and semiarid habitats in open areas with sparse plant cover (TPWD 2009g). They dig for 

hibernation, nesting, and insulation purposes, and are commonly associated with loose sand or 

loamy soils. Populations have declined precipitously in eastern Texas and their decline may be 

related to the spread of fire ants, use of insecticide to control fire ants, heavy agricultural use of 
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NUREG-1937 9-114 February 2011 

the land and other habitat alterations (NatureServe 2009b). Another factor implicated in their 

decline is over-collecting for the pet and curio trade. This species is particularly vulnerable to 

the loss of harvester ants which make up nearly 70 percent of their diet. 

Timber/canebrake rattlesnake

The timber rattlesnake (Crotalus horridus) is a State-listed threatened species and is found in 

Austin, Fort Bend, Colorado, and Wharton Counties (TPWD 2009f). It prefers moist lowland 

forests and hilly woodlands or thickets near permanent water sources such as rivers, lakes, 

ponds, stream and swamps (TPWD 2009g). Their range extends from central New England to 

northern Florida, and west to eastern Texas, where its distribution is spotty 

(NatureServe 2009b). 

American peregrine falcon 

The American peregrine falcon (Falco peregrinus anatum) is a State-listed threatened species 

and is found in Austin, Fort Bend, Colorado, and Wharton Counties (TPWD 2009f). The bird is 

a year-round resident and local breeder in west Texas where it nests in tall cliff eyries 

(TPWD 2009g). The bird also migrates across Texas from breeding areas in United States and 

Canada to winter along the coast and farther south. The American peregrine falcon occupies a 

wide range of habitats during migration, including urban areas. Populations are primarily 

concentrated along coast and barrier islands. The birds are low-altitude migrants, with 

stopovers at leading landscape edges such as lake shores, coastlines, and barrier islands. 

Attwater’s Greater Prairie Chicken

The Attwater’s greater prairie-chicken (Tympanuchus cupido attwateri) is a Federally and Statelisted endangered species and is found in Austin, Fort Bend, Colorado, and Wharton Counties 

(FWS 2009a; TPWD 2009f). The prairie chicken lives in the coastal prairie grasslands with tall 

grasses such as little bluestem, Indian grass, and switchgrass. The birds like a variety of tall 

and short grasses (TPWD 2009g). About 25 percent of the remaining population of the birds is 

found on the Attwater Prairie Chicken NWR (NatureServe 2009b) which is approximately 5 mi 

west of the Allens Creek site (STPNOC 2009a). No information was found on the distance the 

birds can travel, but they can have home ranges in excess of 2000 ac (NatureServe 2009b) (the 

refuge covers more than 10,500 ac). 

Bald eagle 

Although recently delisted from a status of Federally-threatened species, the bald eagle 

(Haliaeetus leucocephalus) is State-listed as threatened in Texas and will remain Federally 

protected under the Bald and Golden Eagle Protection Act and the Migratory Bird Treaty Act 

(TPWD 2009f). The species will also continue to be protected under the ESA through 
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February 2011 9-115 NUREG-1937 

management guildelines that will be in place for the next five years. Most eagles breed in 

Canada and the northern United States and move south for the winter (NatureServe 2009b). 

Bald eagles can be year-round residents in areas where water bodies do not freeze. Winter 

roost sites can vary with proximity to food resources and eagles commonly roost communally in 

large trees, preferably snags. The bald eagle is found in Austin, Fort Bend, Colorado, and 

Wharton Counties. 

Interior least tern

The interior least tern (Sternula antillarum athalassos) is a State-listed endangered species and 

is found in Austin, Fort Bend, Colorado, and Wharton Counties (TPWD 2009f). The birds breed 

along major inland river systems, but it appears restricted to less altered and more natural river 

segments (TPWD 2009g). Interior least terns nest on bare or sparsely vegetated sand, shell, 

and gravel beaches, islands, and salt flats associated with rivers and reservoirs. The birds 

prefer open habitat and avoid thick vegetation and narrow beaches. They arrive at breeding 

areas in early April to early June after wintering along the Central American coast and the 

northern coast of South America. 

White-faced ibis 

The white-faced ibis (Plegadis chihi) is a State-listed threatened species and is found in Austin, 

Fort Bend, Colorado, and Wharton Counties (TPWD 2009f). The white-faced ibis prefers 

freshwater marshes where they roost on low platforms of dead reed stems or on mud banks 

(TPWD 2009g). In Texas, they breed and winter along the Gulf coast and may occur as 

migrants in other parts of the State. 

White-tailed hawk

The white-tailed hawk (Buteo albicaudatus) is a State-listed threatened species and is found in 

Austin, Fort Bend, Colorado, and Wharton Counties (TPWD 2009f). In Texas, the white-tailed 

hawk is found near the coast in coastal prairies, cordgrass flats, and scrub-live oak 

(NatureServe 2009b). The hawk is resident from coastal Texas to southern South America 

(Benson and Arnold 2001). 

Whooping crane 

The whooping crane (Grus americana) is a Federally and State-listed endangered species and 

is found in Austin, Fort Bend, Colorado, and Wharton Counties (FWS 2009a; TPWD 2009f). 

They breed in Canada during the summer months and migrate to the Aransas National Wildlife 

Refuge along the Texas coastal plain, staying there from November through March (TPWD 

2009g). Their winter and migrating habitat includes marshes, shallow lakes, lagoons, salt flats, 
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NUREG-1937 9-116 February 2011 

and grain and stubble fields (NatureServe 2009b). Migration habitat includes sites with good 

horizontal visibility, water depth of 30 cm or less, and a minimum wetland size of 0.1 ac for 

roosting. 

Wood stork 

The wood stork (Mycteria americana) is a State-listed threatened species and is found in Austin, 

Fort Bend, Colorado, and Wharton Counties (TPWD 2009f). Nesting appears to be limited to 

Florida, Georgia, and South Carolina. However, they may have formerly bred in Texas (FWS 

2009b), but there are no breeding records since 1960 (TPWD 2009g). Wood storks forage in 

prairie ponds, flooded pastures or fields, ditches, and other shallow standing water, including 

salt-water. The birds usually roost communally in tall snags, sometimes in association with 

other wading birds (i.e., active rookeries). A distinct, non-listed population of wood storks breed 

in Mexico and birds then move into Gulf States in search of mud flats and other wetlands, even 

those associated with forested areas. 

Louisiana black bear

The black bear (Ursus americanus) is on the state endangered species list (TPWD 2009f) due 

to its similarity to the Louisiana black bear (subspecies U. a. luteolus). The Louisiana black 

bear is a Federally and State-listed threatened species; it is not known to be found in Texas, 

although potential habitat exists in the eastern part of the state. Habitat for the Louisiana black 

bear is primarily bottomland hardwoods and floodplain forests; it is also found in upland 

hardwoods, mixed pine/hardwoods, coastal flatwoods, and marshes (TPWD 2009g). 

Red wolf

The red wolf (Canis rufus) is a State-listed endangered species (TPWD 2009f). Red wolves 

inhabited brush and forested areas, as well as the coastal prairies (Davis and Schmidly 1994). 

They formerly ranged throughout eastern Texas, but appear to now be extinct. 

Building Impacts 

Building two nuclear power units at Allens Creek would affect up to 800 ac of land resulting in 

the permanent loss of 300 ac of terrestrial habitat. For the purpose of this assessment, the 

review team assumes that the proposed 9500-ac, multiple-use reservoir would be in place 

before the two new nuclear power units would be built. To accommodate the building and 

operation of two nuclear units on the Allens Creek site, STPNOC would need to clear 

undisturbed terrestrial habitats to tie new power lines with existing lines (STPNOC 2010a). 

Three new corridors would be required to connect to the three closest 345-kV lines in the area 

(STPNOC 2010a). The site is approximately 20 mi west of the 345-kV connection at the 

O’Brien Substation, which connects to multiple double-circuit lines (in Fort Bend County). The 
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site is 30 mi northwest of a 345-kV line between W.A. Parish power plant and the Hill 

Substation, which is a triple-circuit line (in Fort Bend County). The site is also 35 mi northeast of 

a 345-kV line between the Holman and Hill substations (connection could be in either Wharton 

or Colorado Counties). The total combined distance is 85 mi; based on a 200-ft-width corridor, 

installation of new lines would affect 2060 ac. Although the most direct route would be used, 

efforts would be made to avoid natural or man-made areas where important environmental 

resources are located. This applies particularly to the third potential corridor (i.e., between the 

Holman and Hill substations) which would run close to the Attwater Prairie Chicken NWR; the 

corridor would be routed south of FM 3013 to avoid potential conflicts (STPNOC 2009a). 

Erection of the transmission towers and stringing of the lines would be expected to comply with 

all applicable laws, regulations, permit requirements, and use of BMPs (STPNOC 2010a). 

In addition to transmission corridors, there would be possible impacts associated with the 

building of pipelines to deliver makeup water from the river to the reservoir. Transportation 

routes (both road and rail) would also be needed at Allens Creek. Acreage estimates for these 

activities are: 5 ac for 0.7 mi of rail (50-ft width), 36 ac for 4 mi of pipeline for the cooling water 

intake and discharge between the plant and new reservoir (75-ft width), and 11 ac for a 1.2-mi 

access road (75-ft width) (STPNOC 2010a). 

No site-specific reports or surveys on Federally or State-listed species were available for the 

Allens Creek site or for counties affected by transmission line corridors (i.e., Fort Bend, 

Colorado and Wharton Counties). Federally and State-listed species for Austin, Fort Bend, 

Wharton, and Colorado Counties are discussed above. At the site visit in 2008, the presence of 

numerous wetlands and forested areas in the northwest portion of the site was noted; some of 

these areas contained large, old live oaks (NRC 2009). In addition, one parcel of the Attwater 

Prairie Chicken NWR is approximately 5 mi west of the site, while a second parcel is 10 mi west 

of the site (STPNOC 2009a). The refuge contains one of the largest remnants of coastal prairie 

habitat and is home to one of the last populations of the critically endangered prairie chicken 

(FWS 2009c). 

Loss of terrestrial habitat and habitat fragmentation associated with building the two new 

nuclear reactors and the associated new transmission corridors would noticeably alter terrestrial 

resources. Other sources of impacts to terrestrial resources such as increased traffic, noise, 

risk of collision and electrocution, and displacement of wildlife would likely be temporary and/or 

result in minimal impact to the resource. The disturbance footprint for the two new units would 

be small relative to the disturbance footprint for new transmission corridors. 

Operational Impacts 

Impacts on terrestrial ecological resources from operation of two new nuclear units at the Allens 

Creek site include those associated with transmission system structures, and maintenance of 

transmission line corridors. Also, during plant operation, wildlife would be subjected to impacts 
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from increased traffic. An evaluation of specific impacts resulting from transmission corridor

maintenance cannot be conducted in any detail due to the lack of information, such as the 

locations of any new rights-of-way that could result from transmission system upgrades. 

However, in general, impacts associated with transmission line operation consist of bird 

collisions with the lines, EMF effects on flora and fauna, and habitat loss due to corridor 

maintenance. 

Direct mortality resulting from birds colliding with tall structures has been observed (Erickson et 

al. 2005). Factors that appear to influence the rate of avian impacts with structures are diverse 

and related to bird behavior, structure attributes, and weather. Migratory flight during darkness 

by flocking birds has contributed to the largest mortality events. Tower height, location, 

configuration, and lighting also appear to play a role in avian mortality. Weather, such as low 

cloud ceilings, advancing fronts, and fog, also contribute to this phenomenon. Waterfowl may 

be particularly vulnerable due to low, fast flight and flocking behavior (Brown 1993). Although 

additional transmission lines would be required for the two new nuclear units at Allens Creek, 

increases in bird collisions directly attributable to these lines would be minor and would likely not 

be expected to cause a measurable reduction in local bird populations. 

EMFs are unlike other agents that have an adverse impact (e.g., toxic chemicals and ionizing 

radiation) in that dramatic acute effects cannot be demonstrated and long-term effects, if they 

exist, are subtle (NIEHS 2002). A careful review of biological and physical studies of EMFs did 

not reveal consistent evidence linking harmful effects with field exposures (NIEHS 2002). The 

magnetic fields from many lines, at a distance of 300 ft are similar to typical background levels 

in most homes (NIEHS 2002). Thus, impacts of EMFs on terrestrial flora and fauna are of small 

significance at operating nuclear power plants, including transmission systems with variable 

numbers of power lines (NRC 1996). Since 1997, more than a dozen studies have been 

published that looked at cancer in animals that were exposed to EMFs for all or most of their 

lives (Moulder 2003). These studies have found no evidence that EMFs cause any specific 

types of cancer in rats or mice (Moulder 2003). 

The impacts associated with corridor maintenance activities are loss of habitat due to cutting 

and herbicide application and similar impacts where corridors cross floodplains and wetlands. 

The maintenance of transmission-line corridors could be beneficial for some species, including 

those that inhabit early successional habitat or use edge environments. Thus, corridor 

maintenance would not be expected to increase and contribute to cumulative effects. 

The potential effects of operating two new nuclear reactors at the Allens Creek site would be 

primarily associated with maintenance of transmission corridors and increased traffic. 

Operational impacts to terrestrial resources would be expected to be minimal. 
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Cumulative Impacts

The impacts of building and operating two units at the Allens Creek site were evaluated to 

determine the magnitude of their contribution to regional cumulative impacts on terrestrial 

ecological resources. Activities related to building and operating at Allens Creek include loss of 

habitat at the plant site and along the transmission line corridors. The geographic area of 

interest for cumulative impacts at Allens Creek is the intersection of the Western Gulf Coastal 

Plains ecoregion with the Brazos and San Bernard watershed within Austin Colorado, Wharton, 

Waller, and Fort Bend Counties (Figure 9-10). There are a number of past and potential 

projects that could affect the terrestrial and wetland resources at Allens Creek (Table 9-12). 

Past actions included building the W.A. Parish Electric Generating Station approximately 30 mi 

southeast of the site. The generating station occupies about 4650 ac with two multiple-unit 

stations on the site. 

Future activities that potentially could affect terrestrial and wetland resources include road 

expansion and the development of the Allens Creek reservoir. A four-lane toll road with 

frontage roads and a 400-ft corridor is proposed to be developed approximately 40 mi from the 

site. Road expansion and future industrial and urban development would contribute to loss of 

habitat and fragmentation of existing habitats in the area of interest. 

The other future project is building the 9500-ac Allens Creek reservoir for municipal water 

supplies; the timeline for the reservoir indicates construction would begin in 2018 (Brazos 2010). 

The reservoir would have a substantial impact to wetland and forest resources. Acreages for 

the reservoir indicate it would inundate 460 ac of bluff forest, 27 ac of parks, more than 3900 ac 

of grassland, and more than 2600 ac of bottomland forest, including more than 1700 ac of 

wetland (STPNOC 2009c). Most of the wetlands were mapped as Brazoria depressional soils 

with the deepest depressions having a meander pattern, and are probably the remnants of 

former cutoff channels or oxbow lakes. These depressions are in bottomland forests. The 

dominant tree in the depressions is weedy hackberry (Celtis sp.), with green ash (Fraxinus 

pennsylvanica) in the wetter areas. 

The review team is also aware of the potential for GCC affecting the terrestrial resources in the 

geographic area of interest. The impact of GCC on plant and wildlife species and their habitat in 

the geographic area of interest is not precisely known. GCC could result in sea level rise and 

may result in regional increases in the frequency of severe weather, decreases in annual 

precipitation and increases in average temperature (GCRP 2009). Such changes in climate 

could alter and fragment key terrestrial habitats (grasslands, forests, and wetlands), and could 

result in shifts in species ranges, diversity, and abundance in the geographic area of interest for 

the Allens Creek site. 

The potential cumulative impact to terrestrial resources within the area of interest given the two 

new reactors at the Allens Creek site and associated new transmission corridors and the 
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proposed reservoir at the site would noticeably alter terrestrial resources. All these activities 

would remove or modify terrestrial habitats with the potential to affect important species living or 

migrating through the area. For the reasons discussed above in Building Impacts and 

Operational Impacts, the incremental contribution of building and operating the two new reactors 

at the Allens Creek site and the associated transmission corridors to the cumulative impacts 

within the geographic area of interest would be significant. 

Summary 

Impacts to terrestrial and wetland resources were estimated based on information provided by 

STPNOC and the review teams own independent review. There would be major localized 

impacts at the reservoir location based on the potential for affecting 3060 ac of forested land, 

including loss of high quality bottomland hardwood habitat and possible impacts to a number of 

protected species that could potentially occur in the area. In addition, there is the uncertainty in 

the possible routing of new transmission line corridors that could affect more than 2000 ac, 

possibly resulting in substantial impacts to terrestrial resources. Based on the information 

provided by STPNOC and the review team’s assessment, the review team concludes that the 

cumulative impacts within the area of interest on terrestrial plants and animals, including 

threatened or endangered species, and wildlife habitat in the region would be MODERATE. 

The incremental contribution of impacts on terrestrial resources from the building footprint and 

associated transmission lines would be significant. 

9.3.3.4 Aquatic Resources 

The following impact analysis includes impacts from building activities and operations. The 

analysis also considers other past, present, and reasonably foreseeable future actions that 

impact aquatic resources, including other Federal and non-Federal projects listed in Table 9-12. 

For the analysis of aquatic ecological impacts at the Allens Creek site, the geographic area of 

interest is considered to be Allens Creek and the Brazos River drainage, upstream and 

downstream to the next major tributaries from the confluence of Allens Creek, because this is 

the area that the aquatic resources could be affected by new nuclear units. 

Aquatic resources at the Allens Creek alternative site are associated primarily with the Brazos 

River and Allens Creek, as well as onsite ponds and drainages (Figure 9-10). The Brazos River 

would be the major source of water for the proposed 9500-ac, off-channel reservoir at the site. 

Allens Creek originates southeast of the town of Sealy, and flows south through mostly open 

country for 9.9 mi before making a strong turn to the east, emptying into the Brazos River after 

another 3.7 mi (Linam et al. 1994; STPNOC 2010a). The onsite ponds and drainages are 

mostly associated with wetlands. 

The reach of the Brazos River through the Allens Creek site has been designated by TPWD as 

an ecologically significant stream segment. The characteristics of the reach that are 
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ecologically significant include hydrological functions, riparian conservation and the presence of 

unique communities within the vicinity of the Allens Creek site (TPWD 2010). 

A reservoir at Allens Creek has been part of Texas Water Development Board’s plans for some 

time. In preparation for the reservoir’s development, several assessments have been 

conducted to characterize the fish and macroinvertebrates as well as to evaluate instream flow 

for the support of aquatic life. Linam et al. (1994) inventoried and assessed the fish in Allens 

Creek above and through the area proposed to be inundated for construction of a reservoir as 

well as at and below the confluence of the creek with the Brazos River. Wood et al. (1994) 

assessed macroinvertebrates at the same sampling stations as Linam et al. (1994) in Allens 

Creek and the Brazos River. Gelwick and Li (2002) evaluated the mesohabitat use and 

community structure of the Brazos River for 10 km above and below the confluence with Allens 

Creek. Osting et al. (2004) prepared an instream flow study for the lower Brazos River using 

the aforementioned studies as well as others to evaluate impacts to the hydrology and aquatic 

life from the proposed Allens Creek Reservoir. 

Linam et al. (1994) collected fish, habitat characteristics, and physiochemical measurements to 

characterize the Index of Biotic Integrity (IBI) of the fish community in the region of the Allens 

Creek alternative site. Forty-four fish species were collected in September and November 1993, 

from six sites, including four sites in Allens Creek, one at the confluence of Allens Creek with the 

Brazos River, and another downstream of the confluence. Western mosquitofish (Gambusia 

affinis) was the most abundant fish species at all but two sampling stations in Allens Creek. At 

the first sampling location within the proposed inundation area for the reservoir, pirate perch 

(Aphredoderus sayanus) slightly outnumbered the mosquitofish in September, whereas longear 

sunfish (Lepomis megalotis) outnumbered the mosquitofish in November. Red shiner 

(Cyprinella lutrensis) was the most abundant species at the confluence of Allens Creek and the 

Brazos River in November, and dominated both collections at sites within the Brazos River. 

Bullhead minnow were more numerous than red shiners at the last sampling location within 

Allens Creek. No one cyprinid species dominated the three upstream stations in Allens Creek, 

but blacktail shiner was the most numerous cyprinid in most upstream collections. This shift in 

cyprinid abundance between the lower collection locations on Allens Creek may be related to 

factors including conductivity, turbidity, and siltation, and perhaps the influence of wastewater 

discharged from the City of Wallis treatment plant. Linam et al. (1994) speculated that red 

shiners and bullhead minnows appear better suited than many freshwater fishes (including 

blacktail shiners) to such physicochemical conditions, providing them an advantage over other 

cyprinids in the lower reach of Allens Creek and the Brazos River. Biotic integrity of the sampling 

locations varied over time. The sampling location furthest upstream in Allens Creek was 

consistently scored as good biotic integrity, while the next sampling station downstream was fair 

to good integrity class. The lower two sampling locations in Allens Creek had a biotic integrity 

ranging from excellent to good over the sampling period. At the confluence of Allens Creek and 

the Brazos River the biotic integrity ranged from good to fair. The Brazos River sampling 
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location ranged from good/excellent to good in biotic integrity. The authors concluded that the 

species richness in the vicinity of study was comparable to minimally disturbed streams in Texas. 

They also concluded that the creation of a reservoir and inundation of Allens Creek would likely 

shift the fish community towards species more suited for lentic rather than lotic habitats. 

Wood et al. (1994) sampled at the same locations as Linam et al. (1994) during September and 

October 1993. Overall, 32 macroinvertebrate taxa were identified from benthic and snag 

habitats. The most common taxa were insects (78 percent), with the remaining number of 

organisms divided among Amphipoda (4 percent), Annelida (7 percent), Bivalvia (4 percent), 

Decapoda (7 percent) and other minor taxa. Benthic habitats were dominated by Annelida 

(11 percent), Chironomidae (Diptera) (50 percent), Baetis spp. (Ephemeroptera) (8 percent), and 

Popenaias sp. (unioid mussel) (6 percent). The dominant taxa for snag habitats were 

Chironomidae (73 percent), Hydropsyche spp. (Tricoptera) (10 percent), Leptohyphes spp. 

(Ephemeroptera) (5 percent), and Argia spp. (Odonata) (3 percent). Chironomids were the most 

numerous organisms collected in both snag and benthic habitats with densities ranging from 9 to 

more than 1000 organisms per square meter. Snag habitats had the greatest density of 

macroinvertebrates, with more than 2000 organisms per square meter. Snags and large woody 

debris in the stream beds created important structural components for macroinvertebrates by 

increasing the surface area for their food source, and in turn create essential food resources for 

the fish community. The authors characterized the region as relatively high stress environments 

for macroinvertebrates due to the rapid fluctuations in water level, temperature, and substrate 

movement. The results of the macroinvertebrate community assessment indicated a slightly 

impaired to moderately impaired system and that some level of impact was occurring from the 

wastewater effluents entering Allens Creek from the Cities of Sealy and Wallis, as well as from 

agricultural and ranching activity in the watershed. Interestingly, the only bivalve mollusk 

collected was identified as the unioid mussel genus, Popenaias. The only species in Texas of 

this genus is P. popeii, the Texas hornshell. TPWD did not identify this species of freshwater 

mussel in Austin County. The FWS lists the Texas hornshell as a candidate species, and it is 

considered a proposed threatened species by TPWD. From 74 to 153 specimens of this species 

were collected from the upper reach sampled in Allens Creek, and the number of specimens 

declined in the lower sampling locations along the creek. Additional specimens were collected in 

the Brazos River sampling location (Wood et al. 1994). 

Gelwick and Li (2002) analyzed fish habitat utilization on the basis of visually delineated 

mesohabitats in the Brazos River above and below its confluence with Allens Creek, and 

included information about fish habitat at different flow conditions. From September 2001 

through August 2002, six collections were completed over a range of river discharges, and 

43 species representing 14 families of fish species were collected. Red shiners and bullhead 

minnows accounted for 67.4 percent and 16.9 percent of the collections, respectively. Other 

common species (abundances exceeding 1 percent of overall collections) were ghost shiner 

(Notropis buchanani), silverband shiner (N. shumardi), striped mullet (Mugil cephalus), and 
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mosquitofish. Notably, three individuals of sharpnose shiner (Notropis oxyrhynchus), a 

candidate species for Federal listing by FWS, were collected in the confluence of Allens Creek 

and the Brazos River. As did Linam et al. (1994), the authors calculated the IBI for the 

mesohabitats that were evaluated. Based on seined samples, all the sites in the reach of the 

Brazos River that was included in the study had IBI metrics of excellent across all six collections 

over a range of flows, except for a good rating in September 2001. The authors noted that their 

study reach also scored consistently higher than the scores for seine and electrofishing 

collections calculated previously in the Brazos River, where that study sampled smaller areas of 

the river than their study. Overall, the authors found that no significant fish habitat utilization 

variation in the Brazos River in the vicinity of the Allens Creek alternative site could be explained 

by visually-classified mesohabitat and that the fish communities were habitat generalists. 

Osting et al. (2004) used the available assessments of aquatic communities in Allens Creek and 

the Brazos River to identify potential impacts from the construction of a reservoir at the Allens 

Creek site. The analyses focused on hydrology, fish habitat, and the potential for salinity 

migration in the lower Brazos River. The authors used three different methods to investigate the 

distribution of fish species within aquatic habitats in the vicinity of the alternative site, and found 

that two of the analyses indicated fish communities were made up of habitat generalists, and 

one analysis indicated some degree of habitat specialization. This indicated that fish species 

relationships related to specialized habitat conditions was strong for some species, and 

identified fish indicators for habitat evaluations. The resulting hydrodynamic model predicted 

that Allens Creek Reservoir would not be anticipated to have significant effect on salinity 

migration in the lower Brazos River estuary. 

Within Allens Creek and the Brazos River drainage, upstream and downstream to the next 

major tributaries from the confluence of Allens Creek, there are a number of past, present and 

potential projects that could affect the aquatic resources (Table 9-12). Past actions included 

building and operating the coal- and gas-powered W.A. Parish Electric Generating Station and 

the wastewater treatment systems for the Cities of Sealy and Wallis. TCEQ, Brazos River 

Authority and other state agencies have been planning on construction of a reservoir at the 

Allens Creek site and the water would be available for multiple uses, including power 

production. The building of new nuclear units, include a water intake and discharge systems 

with associated pipelines from the Brazos River to the new site, inundation of Allens Creek for 

development of a reservoir, and associated transmission corridors to connect with the existing 

power grid. Without having the specific plans for locating all facilities at the Allens Creek site, 

the potential for impacts from building and operation of the new units to aquatic biota are 

assumed to be primarily to the organisms inhabiting the Allens Creek and the Brazos River. 

Non-Native and Nuisance Species 

No non-native or nuisance species have been recorded in the area as a problem. However, 

there are numerous nuisance aquatic species that TPWD considers to be ubiquitous across 
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waterways in Texas. TPWD works to educate recreational boaters to remove nuisance aquatic 

plant species across the state and in the area of the Allens Creek site. These species include: 

hydrilla, waterhyacinth, and giant salvinia. In addition, the Brazos River basin is known to have 

a number of non-native fish introduced to its waters including: common carp, grass carp, 

blacktail shiner, bullhead minnow, rudd, black buffalo, black bullhead, western starhead 

topminnow, redspotted sunfish, tadpole madtom, plains killifish, yellow perch, and walleye 

(Thomas et al 2007; Hassan-Williams and Bonner 2009; TPWD 2009h). The introduced 

bullhead minnow and blacktail shiner have become some of the most abundant species in 

Allens Creek and at the confluence with the Brazos River (Linam et al. 1994; Gelwick and Li 

2002). 

Important Species 

Osting et al. (2004) reported that TPWD observed very little recreational fishing during creel 

assessments by TPWD on the Brazos River. Catfish were the most sought after fish in the 

area, including channel, blue, and flathead catfish. The greatest catch per unit effort (CPUE) in 

the Brazos River at Simonton (downstream of confluence with Allens Creek) was for channel 

catfish, followed by flathead catfish and blue catfish. In the vicinity of the Allens Creek site on 

the Brazos River, recreational boating is limited because steep banks make access difficult and 

state parks and wildlife management areas that support recreational boating are far away. 

There are no Federally listed species in Austin County. However, the FWS considers the 

sharpnose shiner a candidate for listing (Table 9-15) (TPWD 2009d; FWS 2009a). Gelwick and 

Li (2002) reported finding three sharpnose shiners at their sampling location in the confluence of 

Allens Creek and the Brazos River; Linam et al. (1994) did not collect this species almost a 

decade earlier. TPWD has identified several rare and protected species in Austin County: a 

mayfly species (Pseudocentroptiloides morihari) as well as the freshwater mussels rock 

pocketbook (Arcidens confragosus) and pistolgrip (Tritogonia verrucosa). The rare and 

protected mayfly is a benthic macroinvertebrate, which lives on the bottom of streams until it 

emerges from the water as a flying adult (TPWD 2009i). In addition, TPDW lists as threatened 

three species of freshwater, unioid mussels that are found in Austin County: smooth 

pimpleback (Quadrula houstonensis), false spike mussel (Quincuncina mitchelli), and Texas 

fawnsfoot (Truncilla macrodon) (Table 9-15) (TPWD 2009i; 35 Texas Register 249). Not much 

is known about the distribution of these mussels in Austin County, and the only known survey 

for benthic macroinvertebrates did not collect these species (Wood et al. 1994). However, 

these types of mussels, known as unioid mussels, are found in various water flows, from fast 

moving riffles in streams to quiescent ponds. Each species has adapted to a particular flow 

regime. These unioid mussels have a larval stage called a glochidium. For glochidia to mature 

to juvenile mussels, they must live as a parasite in the gill tissues of a host fish. An important 

component to the distribution of freshwater mussels in various water bodies is associated with 

the relationship between the mussels and the host fish (Strayer 2008). 
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Table 9-15. Federally and State-Listed Aquatic Species that are Endangered, Threatened, and 

Species of Concern for Austin County 

Scientific Name Common Name Federal Status(a) State Status(b)

Fish 

Notropis oxyrhynchus sharpnose shiner FSC 

Mussel 

Quadrula houstonensis smooth pimpleback T 

Quincuncina mitchelli false spike mussel T 

Truncilla macrodon Texas fawnsfoot T 

(a) Federal status rankings determined by the FWS under the Endangered Species Act, FSC = 

Federal Species of Concern (FWS 2009a). 

(b) State species information provided by TPWD, T = State Listed Threatened (TPWD 2009d; 35 

Texas Register 249).

Building Impacts 

For the purpose of this assessment, the review team assumes that the proposed 9500-ac, 

multiple-use reservoir would be in place before the two new nuclear power units would be built. 

Impacts associated with the building of the reservoir are considered below in the cumulative 

impacts discussion. 

Water intake and discharge structures along the shoreline of the Brazos River would be 

required for the Allens Creek reservoir at the Allens Creek site (STPNOC 2010a). Building a 

new intake and discharge in the Brazos River would likely require dredging and other significant 

alterations to the shoreline aquatic habitat. These activities, which would be unrelated to the 

building and operating of two nuclear units at the Allens Creek site, would be permitted by the 

Corps and the construction activities would have to meet all State water quality requirements. 

Building these structures on the Brazos River would result in the temporary displacement of 

aquatic biota within the vicinity of both structures. It is expected that the motile aquatic 

organisms would be displaced temporarily during building, including such fish species as the 

sharpnose shiner. However, the sessile aquatic biota (e.g., mussels) would be lost during 

building activities if the river substrate was removed or sedimentation covered the bottom of the 

river burying the organisms. Organisms like the mussels could possibly recolonize the 

disturbed river substrate with time. If required by TPWD, State-listed threatened mussels could 

be surveyed and removed before building activities as a mitigation action. For the most part, 

the impacts on aquatic organisms would be temporary and largely mitigable through the use of 

BMPs, e.g., silt screens. 

Building transportation routes (heavy haul road and railroad spur), pipelines and transmission 

lines for the Allens Creek site would result in the temporary displacement of some aquatic biota. 

Locations for these systems have not been identified. Building new transmission line corridors 

could result in noticeable impacts; however, effects to the aquatic resources could be minimized 
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by routing the corridor away from water bodies or spanning the water bodies without placement 

of transmission tower footings in aquatic resource habitats. BMPs would be used while building 

these corridors to reduce impacts such that they would be temporary and localized 

(STPNOC 2010a). Depending on whether or not the intake and discharge structure are built in 

the reservoir before or after filling of the reservoir, some adverse impacts to aquatic biota could 

occur. Such impacts would be confined in their extent and temporary, and would affect similar 

species and habitats that would be affected during construction of the intake structure on the 

Brazos River. 

Building the intake and discharge structures on the Brazos River and in the new reservoir would 

affect the aquatic communities but the areas would be recolonized after building these 

structures was completed. Building of the transportation routes, transmission corridors, and 

pipelines would result in temporary and localized effects on aquatic communities. 

Operation Impacts 

The Brazos River instream flow study determined that the aquatic resources could be 

maintained with diversion of water to the proposed Allens Creek reservoir (Osting et al. 2004). 

Water withdrawal and water return to the Brazos River could be managed in such a way that 

impacts to this ecologically significant stream section could be maintained with minimal impacts 

to the aquatic resources and associated riparian habitat (STPNOC 2010a). 

Impingement, entrainment, and entrapment of organisms from the Brazos River and from the 

reservoir would likely be the most significant impacts to the aquatic population that could occur 

from operation of two new nuclear units at the Allens Creek site. EPA’s design criteria for 

316(b) Phase 1 regulations (66 FR 65255) for intake structures would minimize impacts to 

aquatic biota in the reservoir. The design criteria include: (1) closed-cycle cooling system that 

meets the EPA’s Phase I regulations for new facilities; (2) maximum through-screen velocity of 

0.15 m/s (0.5 ft/s) at the cooling water intake; and (3) intake flow of less than or equal to 

5 percent of the mean annual flow (STPNOC 2010a). Compliance with these regulations would 

minimize impingement, entrainment, and entrapment impacts to the aquatic biota in the 

reservoir. 

Operational impacts associated with water quality, physical, and thermal characteristics of the 

discharge cannot be determined without additional detailed analysis. The proposed reservoir for 

the Allens Creek site would likely evolve in a similar fashion to the MCR at the STP site, where, 

with time, the reservoir has developed similar aquatic resources to that in the lower Colorado 

River and acclimated to the discharges of the operating reactor units. Impacts to the Brazos 

River would depend on the type of cooling system for the new units as well as the volume, 

frequency, and water characteristics of the discharge. These types of impacts can be addressed 

and minimized through operational procedures and the permitting process with TCEQ. 
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Operational impacts to aquatic biota from onsite activities and in the transmission corridors 

would also be minimal assuming BMPs are used for maintenance of these areas and corridors. 

SWPPPs would ensure that impacts to biota from erosion and sedimentation would be minimal 

through the use of silt screens and controls for managing stormwater. These controls would be 

important for habitat quality and survival of benthic biota in the downstream drainages. 

Based on operation of the CWS, impacts to aquatic communities in the Brazos River and 

reservoir could result from impingement, entrainment, and entrapment as well as thermal, 

chemical, and physical characteristics of the discharge. STPNOC commits to compliance with 

State and Federal regulations for operation of intake and discharge structures associated with 

the nuclear units that would be protective of aquatic resources. Once a community is 

established in the new reservoir, long-term effects from operation of the CWSs are not expected 

to noticeably alter aquatic communities in the Brazos River and reservoir. 

Cumulative Impacts 

Within Allens Creek and the Brazos River drainage, upstream and downstream to the next 

major tributaries from the confluence of Allens Creek, current and future plans for water usage 

by municipalities and industries have influenced the aquatic ecology of the region. Included in 

such plans is the Allens Creek Reservoir to supply water to the City of Houston. 

Impacts of building the reservoir at Allens Creek may be significant depending on the siting of 

the reservoir. The proposed plans are for inundating approximately 7 to 9 mi of Allens Creek to 

the confluence with the Brazos River. Impacts from onsite building activities that have the 

potential to cause erosion and sedimentation to the local water bodies would be controlled or 

minimized by the implementation of an SWPPP (STPNOC 2010a). Habitat for aquatic species, 

including any spawning areas for fish species that are dependent on flowing water, that are 

found in Allens Creek and the associated wetlands and drainages would be lost when these 

water bodies are inundated to create the reservoir. In addition, the snags and large woody 

debris in the lower reaches of Allens Creek would be less likely to accumulate after building the 

reservoir, and this habitat was thought to contribute to the high abundance of 

macroinvertebrates in the creek (Wood et al. 1994). Most freshwater mussel species are 

adapted to a specific flow regime, and the inundation of Allens Creek could affect the 

distribution of the organisms in the region (STPNOC 2010a; TPWD 2009i). If habitat for the 

sharpnose shiner or any of the State-listed mussels is found in the area to be inundated for the 

creation of the reservoir, the FWS and/or TPWD might require mitigation activities. 

Other uses of the reservoir would include cooling for power production and recreation, 

e.g., fishing and boating. Allens Creek and possibly the proposed reservoir would be influenced 

mostly by discharges from the wastewater treatment plants for the Cities of Sealy and Wallis as 

well as agricultural development and ranching activities along the riparian areas (Linam et al. 

1994; Wood et al. 1994). The coal- and gas-powered W.A. Parish Electric Generating Station is 
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NUREG-1937 9-128 February 2011 

approximately 40 mi downstream of the Allens Creek site, and uses water from the Brazos River 

stored in Smithers Lake. Building in and along the shoreline of the Brazos River for the Allens 

Creek site is not likely to influence the sediment transport and aquatic ecology beyond the 

geographic area of interest because the activities would be relatively short in duration and 

BMPs would minimize impacts. In addition, Osting et al. (2004) found that salinity intrusion up 

the Brazos River is unlikely based on its instream modeling of a reservoir at Allens Creek. 

Continued urbanization and agricultural practices could affect aquatic communities in the Allens 

Creek geographic area of interest in the foreseeable future. Expansion of urban areas in the 

Brazos River drainage could increase water use, decrease available water for aquatic 

resources, and increase nonpoint pollution. The effects of continued agricultural practices could 

result in additional habitat loss and/or degradation due to irrigation using surface waters and 

groundwater withdrawal, nonpoint source pollution, siltation, and bank erosion. 

As mentioned above in the terrestrial section, GCC could result in regional increases in the 

frequency of severe weather, decreases in annual precipitation, and increases in average 

temperature (GCRP 2009). The decrease in precipitation combined with elevated water 

temperatures and evaporation could result in more frequent droughts, which could reduce 

aquatic habitat. Loss of habitat could cause shifts in species ranges, diversity, and abundance 

in the geographic area of interest for the Allens Creek site (GCRP 2009). Specific predictions 

on aquatic habitat changes and impacts to aquatic species in this region resulting from GCC are 

inconclusive at this time. Because of the regional nature of climate change, the impacts related 

to GCC would be similar for all the alternative sites, as they are all in the Great Plains region. 

Based on building and operation of two new nuclear units at the Allens Creek alternative site 

and other projects and influences in the region of influence for aquatic resources, the 

cumulative impacts would be noticeable but not destabilizing. All these activities would alter the 

aquatic habitats and potentially change the species composition and diversity in the affected 

water bodies. 

Summary 

The review team concludes that the impacts from building and operating two new nuclear units 

at the Allens Creek site would be minimal. Building of a multi-use reservoir at Allens Creek 

would inundate existing water bodies and destroy habitat for aquatic resources that are 

dependent on flowing water. Based on the information provided by STPNOC and the review 

team’s independent evaluation, the review team concludes that the cumulative impacts of 

building and operating two new reactors on the Allens Creek site combined with other past, 

present, and future activities on most aquatic resources in the Brazos River drainage would be 

MODERATE. The incremental contribution of building and operating the two new reactors at 

the Allens Creek site to the cumulative impacts within the geographic area of interest would not 

be significant. 
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9.3.3.5 Socioeconomics 

The following impact analysis includes impacts from building activities and operations. The 

analysis also considers other past, present, and reasonably foreseeable future actions that 

impact socioeconomics, including other Federal and non-Federal projects listed in Table 9-12. 

For the analysis of socioeconomic impacts at the Allens Creek site, the geographic area of 

interest is considered to be the 50-mi region centered on the Allens Creek site with special 

consideration of Austin and Fort Bend Counties as that is where the review team expects 

socioeconomic impacts to be the greatest. In evaluating the socioeconomic impacts of site 

development and operation at the Allens Creek site near Wallis and Sealy, in Austin County, the 

review team undertook a reconnaissance survey of the site using readily obtainable data from 

the Internet or published sources. Impacts from both site development and station operation 

are discussed. 

Physical Impacts 

Many of the physical impacts of building and operation would be similar regardless of the site. 

Building activities can cause temporary and localized physical impacts such as noise, odor, 

vehicle exhaust, vibration, shock from blasting (if used), and dust emissions. The use of public 

roadways, railways, and waterways would be necessary to transport construction materials and 

equipment. Offsite areas that would support building activities (for example, borrow pits, 

quarries, and disposal sites) would be expected to be already permitted and operational. 

Potential impacts from station operation include noise, odors, exhausts, thermal emissions, and 

visual intrusions (the latter are covered under aesthetics and recreation). New units would 

produce noise from the operation of pumps, cooling towers, transformers, turbines, generators, 

and switchyard equipment. Traffic at the site also would be a source of noise. Any noise 

coming from the proposed STP site would be controlled in accordance with standard noise 

protection and abatement procedures. This practice also would be expected to apply to all 

alternative sites, including the Allens Creek site. Commuter traffic would be controlled by speed 

limits. Good road conditions and appropriate speed limits would minimize the noise level 

generated by the workforce commuting to the alternative site. 

The new units at the Allens Creek site would likely have standby diesel generators and auxiliary 

power systems. Permits obtained for these generators would ensure that air emissions comply 

with applicable regulations. In addition, the generators would be operated on a limited, shortterm basis. During normal plant operation, new units would not use a significant quantity of 

chemicals that could generate odors that exceed odor threshold values. Good access roads 

and appropriate speed limits would minimize the dust generated by the commuting workforce. 

Based on the information provided by STPNOC and the review team’s independent evaluation, 

the review team concludes that the physical impacts of building and operating two nuclear units 

at the Allens Creek site would be minimal. 
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NUREG-1937 9-130 February 2011 

Demography 

The Allens Creek site is located in Austin County (2008 population 26,851), 4.4 mi north of the 

city of Wallis (2007 population 1287) and 7.3 mi southeast of Sealy (2008 population 6190), and 

within 50 mi of the outer edges of the Houston Metropolitan area (2008 population 5.7 million) 

(USCB 2009a). Fort Bend County (2008 population 532,141) was one of the fastest growing 

counties in the United States during recent decades as Houston suburbs have expanded 

westward into the county (USCB 2009a). 

STPNOC estimated the peak number of construction workers would be 5950. Approximately 

900 operations workers would also be onsite during the final phase of building activities 

(STPNOC 2010a). Based on assumptions in Section 4.4 concerning in-migration for Units 3 

and 4 in Matagorda County, and for comparability with the analysis in that section, the review 

team assumed that 50 percent or 2975 construction workers would in-migrate. Because no 

information is available on where the workforce would live, the review team assumed that half of 

the plant workforce would move to Austin County and the other half to Fort Bend County. 

Eighty percent of in-migrating construction workers would bring a family. Harris County, which 

includes Houston, would likely see an in-migration of workers as well, but considering the large 

populations of this county and the relatively small number of in-migrants they would be easily 

absorbed without noticeable impacts. All operations workers would in-migrate and all would 

bring a family. A family size of 3.25 was used for construction workers for a total peak site 

development related population increase of 8330 (7735 in-migrating workers and family 

members and 595 workers without family). An average family size of 2.74 for the operating 

workforce (see Section 5.4) would result in a total in-migrating operations-related population of 

2466 (900 operations workers plus family). Therefore, the total expected in-migrating 

population (site development and operations) at peak building would be 10,796. 

Because the assumed in-migrating population would be about 1 percent of the total population 

for Fort Bend County, the demographic impacts of building activities are expected to be minimal 

for this county. However, the impacts would likely be significant in the smaller Austin County, 

where the in-migrating population represents 20 percent of the current population. If the facility 

is completed and commences operations, the operational workforce would number about 959 

workers, 900 of whom would be at the site during building activities and are included in the 

above analysis. The review team expects that the demographic impact during operation would 

be minimal for all counties in the region. Based on the information provided by STPNOC and 

the review team’s independent evaluation, the review team concludes that the demographic 

impacts of building and operating two nuclear units at the Allens Creek site would be significant. 

Taxes and Economy 

As described in Section 5.4.3.2, STPNOC estimates it would spend $60 million annually for 

goods and services related to the new units, of which about 20 percent ($12 million) would be 
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February 2011 9-131 NUREG-1937 

spent locally (STPNOC 2010a). STPNOC estimated if the units were 100 percent taxable, 

annual franchise taxes for Unit 3 would be $4.7 to $5.4 million and Unit 4 would have payments 

of $3.9 to $4.7 million which would represent less than 1 percent of the State’s annual franchise 

tax revenues. 

The largest tax impacts would come from property taxes related to the building and operations 

activities of the two units. The private owners of any new units built at the Allens Creek site 

would pay taxes to the county, any applicable special districts that exist within the county and 

the local school district in which the land sits. During the building process, county property tax 

payments would be based on the cost of building the units and determined in accordance with 

state law using mutually agreed on appraisal formulas (STPNOC 2010a). During operations 

property taxes would range from $6.10 million to $13.86 million. Taxes from the nuclear plant 

would represent a 58 to 131 percent increase over the 2008 Austin County taxes levied of $10.6 

million. Development of the Allens Creek site for a nuclear power plant also would require a 

cooling water source. STPNOC believes that proposed 9500-ac reservoir to the east of the 

power plant footprint could perform that function. Such a reservoir, if built, could remove 

approximately 9500 ac from the property tax rolls, with a resulting significant tax loss to Austin 

County. 

Increased property values in the district would increase the tax payments made to Brazos 

independent school district (ISD), which is a Texas Education Code Chapter 42 “poor district” 

(TEA 2009) This means the Brazos ISD could keep most if not all of the additional tax revenues 

generated by the development of a nuclear plant within the district lines. Although the exact 

amount currently is unknown, the tax payments are likely to represent a substantial beneficial 

impact for both the small, rural county of Austin County and for Brazos ISD. Brazos ISD’s total 

tax revenue in 2008 was $9.2 million (Global Scholar 2008). 

Economic impacts would be spread across the 50-mi region but would be greatest in Austin 

County. Austin County per capita income for 2007 is $35,580 and $41,779 for Fort Bend 

County (Texas Association of Counties 2009c, d). The 2008 unemployment rate for Austin 

County and Fort Bend County was 4.3 percent and 4.5 percent, respectively (Texas Association 

of Counties 2009c, d). The wages and salaries of the building- and operations-related 

workforces would stimulate local economies and increase business activity, particularly in the 

retail and service sectors. This would have a positive and noticeable impact on the business 

community and could provide opportunities for new businesses and increased job opportunities 

for local residents. Based on the information provided by STPNOC and the review team’s 

independent evaluation, the review team concludes that the tax and economic impacts of 

building and operating two nuclear units at the Allens Creek site would be significant and 

beneficial. 
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NUREG-1937 9-132 February 2011 

Transportation and Housing 

Both Austin and Fort Bend Counties have well developed road networks. The local 

transportation network near the site includes Interstate 10 (I-10), US-90, SH-36, and several FM 

roads. Primary access to the site is from I-10 which is approximately 6 mi south of the site. 

Commuters would likely take I-10 to SH 36, a two lane road in good condition, which provides 

direct access to the site. A new access road would need to be constructed to provide access 

inside the site. I-10 east and west of Sealy has an annual average daily traffic count (AADT) of 

46,000 and 38,000, respectively. The I-10 SH 36 intersection has an AADT of 22,000 but the 

part of SH 36 between Sealy and Wallis, where direct access to the site would be, is only 5900. 

The most likely pinch points would be at several intersections on SH 36 between Sealy and 

Wallis. Provision would have to be made to cross the rail line that closely parallels SH 36 

between the highway and the site. Rail traffic is heavy enough on this corridor to possibly 

require coordination between rail and site vehicular traffic. Less than a mile of rail line would 

need to be constructed (STPNOC 2010a). The review team expects the transportation impacts 

from building a plant at the Allens Creek site would be noticeable but not destabilizing on SH 36 

and would warrant mitigation. Operation impacts would be minimal due to the much smaller 

workforce and because roads would have been improved during the site development phase. 

Approximately 3875 construction and operations workers could migrate into the region during 

peak site development. During operations the workforce is expected to be about 959 workers of 

which 900 are included in the 3875 workers needing housing during peak building activity. 

U.S. Census Housing Profile for Austin County estimated a total housing stock of 10,822 units 

with a rental vacancy rate of 11.4 percent. Approximately 1487 housing units were unoccupied 

at the time of the survey (USCB 2009e). The U.S. Census Housing Profile for Fort Bend County 

estimated a total housing stock of 148,484 units with a rental vacancy rate of 8.7 percent. 

Approximately 9209 housing units were unoccupied at the time of the survey (USCB 2009f). 

Some workers may choose to find housing such as an apartment or house while others may inmigrate with their own housing in the form of a travel trailer. The review team expects that the 

in-migrating workforce would be absorbed easily into the existing housing stock in Fort Bend 

County and the region without a measurable impact, but especially if workers concentrate closer 

to the plant, the impacts could be significant in Austin County due to the smaller number of 

housing units available. Based on the information provided by STPNOC and the review team’s 

independent evaluation, the review team concludes that the housing impacts of building and 

operating two nuclear units at the Allens Creek site would be noticeable and possibly significant. 

Public Services and Education 

The influx of construction workers and plant operations staff settling in the region could impact 

local municipal water and water treatment facilities and other public services in the region. 

These impacts would likely be in proportion with the demographic impacts experienced in the 

region, unless these resources have excess capacity or are particularly strained during building, 
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February 2011 9-133 NUREG-1937 

which would decrease or increase the impact, respectively. For example, the largest water 

treatment facilities in Austin County and Fort Bend County have water capacity available that is 

roughly three to ten times current average daily consumption (EPA 2009b), so while they may 

have to build considerable distribution infrastructure they are unlikely to be water capacity 

limited. 

The in-migrating construction workers represent a small portion of the total population of Fort 

Bend County and would likely have a minimal impact on their public services. In the smaller 

Austin County the impacts during building could be more noticeable due to a strain on public 

services from a relatively larger population increase in this county. During operations the impact 

on public services would diminish to minimal levels throughout the region. 

Austin County has 3 independent school districts with 13 schools and Fort Bend County has 6 

independent school districts with 174 schools. The 2007-2008 student enrollments for Austin 

and Fort Bend County are 5641 students and 149,952 students, respectively (NCES 2009). 

The review team expects a peak building-related increase of about 2537 students (1269 in each 

county). The in-migrating students would be less than 1 percent of the current student 

population and would have a minimal impact to schools in Fort Bend County. However, the 

increase would be a 23 percent increase in the student population in Austin County, where the 

review team expects the impact would be significant and potentially destabilizing to this school 

system. The impact from operations-related new students would decline to minimal levels 

everywhere. Based on the information provided by STPNOC and the review team’s 

independent evaluation, the review team concludes that the public service and education 

impacts of building and operating two nuclear units at the Allens Creek site would be significant. 

Aesthetics and Recreation 

Recreation in the area includes the historic Texas Independence Trail, the Stephen F. Austin 

Historical Park, and the Attwater Prairie Chicken National Wildlife Refuge (STPNOC 2009a). 

Building of the reservoir would impact a 7-mi stretch of the Texas Independence Trail. During 

building activities, drivers along the Texas Independence Trail would experience modest 

inconvenience from building activities or by the occasional closure of the road. During 

operations, drivers would receive minimal impacts from additional cars on the road commuting 

to the site. The building and operation of the plant itself and transmission lines to support the 

site would have a noticeable aesthetic impact on the region. Based on the information provided 

by STPNOC and the review team’s independent evaluation, the review team concludes that the 

aesthetic and recreation impacts of building and operating two nuclear units at the Allens Creek 

site would be noticeable. 
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NUREG-1937 9-134 February 2011 

Summary of Socioeconomics 

Physical impacts on workers and the general public include impacts on existing buildings, 

transportation, aesthetics, noise levels, and air quality. Social and economic impacts span 

issues of demographics, economy, taxes, infrastructure, and community services. In summary, 

on the basis of information provided by STPNOC and the review team’s independent evaluation, 

the review team concludes that adverse socioeconomic impacts of the building and operation of 

a new nuclear plant at the Allens Creek site would be minimal for Fort Bend County and most of 

the region, but in Austin County during the building phase they could be noticeable and adverse 

for transportation and public services, and significant and adverse for demographics, housing, 

and education impacts. Aesthetic and recreational impacts would be noticeable and adverse 

during the building phase in Austin County, with noticeable operations phase aesthetic impacts 

in and beyond Austin County along any new transmission corridors. Other operations phase 

adverse impacts would be minimal in Austin County. The impacts on the Austin County 

economy and tax base during plant building and operation likely would be beneficial and 

significant, and they would be beneficial and noticeable in Fort Bend County. They would be 

minimal elsewhere in the region. 

Cumulative Impacts 

For the analysis of socioeconomic impacts at the Allens Creek site, the geographic area of 

interest is the 50-mi region centered on the Allens Creek site with special consideration of 

Austin and Fort Bend Counties as that is where the review team expects socioeconomic 

impacts to be the greatest. After World War II and the introduction of irrigation, agriculture 

supported the local economy in Austin County. Much of the land used for cotton farming was 

converted to ranchland and livestock production became the chief industry after World War II. 

Manufacturing in Austin County also increased after World War II due in part to the heavy 

industry coming out of Houston (TSHA 2009d). Traditionally, Fort Bend County’s economy was 

based on farming and ranching but that has declined over the last several decades. Cotton, 

sorghum and rice are all still important crops in Fort Bend County however farms produce more 

cattle than any other commodity. The county also produces numerous minerals and the first 

oilfields were drilled in the 1920s. The petroleum industry was the most important industry in 

Fort Bend County in terms of taxes generated until the mid 1970’s oil crisis. Due to Houston’s 

westward expansion into Fort Bend County the economy has become much more diverse 

recently (TSHA 2009e). 

In addition to assessing the incremental socioeconomic impacts from the building and 

operations of two additional nuclear units on the Allens Creek site, the cumulative impacts 

analysis also considers other past, present, and reasonably foreseeable future actions that 

could contribute to the cumulative socioeconomic impacts on a given region, including other 

Federal and non-Federal projects and those projects listed in Table 9-12. For the analysis of 
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February 2011 9-135 NUREG-1937 

socioeconomic impacts at the Allens Creek site, the geographic area of interest is considered to 

be the 50-mi region centered on the Allens Creek site. 

The projects identified in Table 9-12 have or would contribute to the demographics, economic 

climate, and community infrastructure of the region and generally result in increased 

urbanization and industrialization. However, many impacts such as those on housing or public 

services are able to adjust over time, particularly with increased tax revenues. Furthermore, 

state and county plans along with modeled demographic projections include forecasts of future 

development and population increases. Because the projects within the review area identified 

in Table 9-12 would be consistent with applicable land-use plans and control policies, the review 

team considers the cumulative socioeconomic impacts from the projects to be manageable. 

There is a plan, at some point in the future, to construct I-69, a remaining element of the former 

Trans-Texas Corridor (TTC) proposal (TxDOT 2010). Current plans call for the highway to 

follow the current path of highway U.S. 59 through the central part of Fort Bend County. The 

highway itself would take a wide swath of land that would be removed from predominately 

agricultural use in the county but may attract commercial and industrial development. 

Construction detours and construction traffic also could disrupt transportation along the corridor 

during the building period in Fort Bend County. The timing of the development is not definite 

and it is not known whether the long-term balance of socioeconomic effects would be beneficial 

or adverse. The short-term aesthetic affects would be noticeable and adverse along the route 

when the project occurs, but the project is not expected to overlap with the building of the 

nuclear reactors at the Allens Creek site. 

The review team concludes that the cumulative socioeconomic impacts of building and 

operating a new nuclear plant at the Allens Creek site would be LARGE and adverse in terms of 

demographics, housing, and education in Austin County during the building phase. 

Transportation, services, aesthetic and recreation impacts would be MODERATE and adverse 

in Austin County during the building phase, with lesser impacts during the operations phase. 

Fort Bend County would experience MODERATE physical (noise and dust), transportation and 

aesthetics impacts, mainly due to I-69 project construction, but also in part due to the impacts of 

building the nuclear plant and associated transmission lines. The impacts on the economy and 

tax base during plant development and operation likely would be beneficial and MODERATE to 

LARGE in Austin County and beneficial and SMALL to MODERATE in Fort Bend County. 

Building and operating a new plant at the Allens Creek site would make a significant, 

incremental contribution to these impact levels. 

9.3.3.6 Environmental Justice 

The following impact analysis includes impacts from building activities and operations. The 

analysis also considers other past, present, and reasonably foreseeable future actions that 

impact environmental justice, including other Federal and non-Federal projects listed in 

Table 9-12. The cumulative environmental justice impacts were assessed for the 50-mi region 
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NUREG-1937 9-136 February 2011 

centered on the Allens Creek site. In 2000, the 50-mi region around the Allens Creek site was 

characterized as 20 percent Black, 0.4 percent American Indian and Alaskan Native, 

5.9 percent Asian, 0.05 percent Hawaiian and Other Pacific Islander, 13 percent all other races, 

and 2.8 percent two or more races, 30.2 percent Hispanic or Latino and 11.6 percent 

low-income (STPNOC 2010a). 

For this analysis of cumulative environmental justice impacts, the geographic area of interest is 

considered to be the 50-mi region surrounding the Allens Creek site and Freeport area in 

Brazoria County, which has a minority population and potentially could be affected if the flow 

regime at the mouth of the Brazos River were to be changed as a result of withdrawing water 

from the river to supply water for the reservoir at the Allens Creek site. The review team 

identified 1946 census blocks groups within the 50 mi region, 1065 of which were classified as 

minority populations (two of them in Austin County and 99 in Fort Bend County) (USCB 2000a). 

One of these block groups in Austin County (near Sealy) and one block group in Waller County 

are within 10 mi of the Allens Creek alternative site. The review team identified 164 census 

block groups classified as low income in the 50-mi region, of which none are in Austin County 

and one in Fort Bend County (USCB 2000c). None of these populations are within 10 mi of the 

Allens Creek alternative site. See Figure 9-11 and Figure 9-12 for the location of minority or 

low-income populations within the 50-mi region. The review team did not locate any minority or 

low-income populations that were located along Allens Creek. Nor did the review team find any 

minority or low-income populations in the first 50 mi of the Brazos River downstream from the 

Allens Creek site or that were engaged in subsistence activity along this river. The review 

team’s analysis did not find any information suggesting that minority or low-income populations 

in the area were dependent on natural resources that would be adversely affected by a nuclear 

power plant at the Allens Creek site. 

There are significant minority populations in Austin, Wharton, Ft. Bend and Harris Counties. 

However, physical impacts of building (noise, fugitive dust, air emissions, and air and water 

emissions) would not impose a disproportionately high and and adverse effect on minority 

populations because of their distance from the Allens Creek site (at least 5 mi even for the 

closest minority populations in Waller County just east of Austin County and in the vicinity of 

Sealy, several miles to the north of the site). The I-69 proposed route cuts through the central 

part of Fort Bend County on the same route as U.S. 59, through the Kendleton area. I-69 

appears to pass through minority and low-income census block groups in Fort Bend County 

(DOT and TxDOT 2007). Much of the I-69 corridor in Fort Bend County passes directly through 

many minority census block groups, and because of the preemptive nature of large highways on 

land use, if built on the U.S. 59 corridor, I-69 has a strong chance of disproportionately 

disrupting neighborhood continuity, displacing existing local services, and interrupting 

community interactions in minority communities within the I-69 highway corridor. The review 
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February 2011 9-137 NUREG-1937 

Figure 9-11. Block Groups with Minority Populations Meeting Environmental Justice Selection 

Criteria Within 50 mi of the Allens Creek Alternative Site (USCB 2000a)
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Figure 9-12. Block Groups with Low-Income Populations Meeting Enviornmental Justice 

Selection Criteria Within 50 mi of the Allens Creek Alternative Site (USCB 2000c) 
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February 2011 9-139 NUREG-1937 

team took into account the U.S. Department of Transportation and TxDOT’s draft EIS for the 

Tier 1 I-69 Trans-Texas Corridor Study (DOT and TxDOT 2007) and adapted it to the U.S. 59 

route (TxDOT 2010). The review team recognizes that more detailed studies will be taking 

place in the future, that initial estimations of environmental justice impacts could change, and 

that re-routing and other mitigation would be taken to minimize impacts on minority and low 

income populations. The impacts of the highway would be significant and potentially 

destabilizing to affected individuals and communities, but appropriate routing might avoid or 

mitigate any disproportionate impact to minority and low-income populations. Depending on the 

exact routing eventually taken by I-69 through Fort Bend County, disproportionate adverse 

impacts associated with I-69 to the noted minority census block groups in Fort Bend County 

could range from minimal to significant and potentially destabilizing. However, the review team 

does not expect that minority and low-income populations in Austin County would be 

disproportionately affected. 

The 9500 ac reservoir for Allens Creek does not appear to infringe on lands occupied by 

minority populations. There are scattered low income populations in Waller, Ft. Bend, and 

Warren Counties beyond 15 mi from the Allens Creek alternative site and a somewhat greater 

concentration in western Harris County more than 30 mi away. There are no identified low 

income populations in Austin County. Because they are a greater distance from the Allens 

Creek alternative site than the minority populations, low-income populations are even less likely 

to experience disproportionately high and adverse environmental impacts from the Allens Creek 

alternative site. 

The city of Freeport is at the mouth of the Brazos River, 60 mi downstream from the Allens 

Creek Site and has a population that is more than 50 percent Hispanic or Latino. Its proportion 

of low-income persons is about 5 percentage points above the Texas state average. However, 

any impacts on the Brazos River at Freeport would be short in duration during the building 

period and negligible during operations. The building and operation of the proposed project at 

the Allens Creek site is unlikely to have any disproportionate adverse impact on any minority or 

low-income populations. See Sections 4.5 and 5.5 for more information about environmental 

justice criteria and impacts. The environmental justice impacts from building and operating two 

nuclear units at the Allens Creek site would be minimal and adverse. 

The cumulative environmental justice impacts in the Allens Creek site area would be SMALL in 

Austin County, LARGE in Fort Bend County and SMALL and adverse elsewhere within the 

50-mi region. However, this cumulative rating is based entirely on the impact of the I-69 project, 

which has an indefinite future schedule. Building and operating two nuclear units at the Allens 

Creek site would not be a significant contributor to these impacts. 
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NUREG-1937 9-140 February 2011 

9.3.3.7 Historic and Cultural Resources 

The following cumulative impact analysis includes building and operating two new nuclear 

generating units at the Allens Creek site. The analysis also considers other past, present, and 

reasonably foreseeable future actions that could impact cultural resources, including other 

Federal and non-Federal projects as listed in Table 9-12. For the analysis of cultural impacts at 

the Allens Creek site, the geographic area of interest is considered to be the APEs that would 

be defined for this site. This includes the physical APE, defined as the area directly affected by 

the site development and operation activities at the site and transmission lines, and the visual 

APE. The visual APE is defined as an additional 1-mi radius around the physical APE 

consistent with the discussion in Section 2.7 about the maximum distance from which the 

structures can be seen. 

Reconnaissance activities in a cultural resource review have particular meaning. Typically, for 

example, it includes preliminary field investigations to confirm the presence or absence of 

cultural resources. However, in developing this EIS, the review team relied upon 

reconnaissance-level information to perform its alternative site evaluation, in accordance with 

ESRP 9.3 (NRC 2000). Reconnaissance-level information is data that are readily available from 

agencies and other public sources. It can also include information obtained through visits to the 

site area. To identify the historic and cultural resources at the Allens Creek site, the following 

information was used: 

• STPNOC ER (STPNOC 2010a) - including the THC’s Texas Archeological Sites Atlas; 

• NRC Alternative Sites Visit March 2008; and 

• Final Environmental Statement – Allens Creek Nuclear Generating Station Units 1 and 2 

(AEC 1974). 

The Allens Creek site is located in Austin County, Texas. The Allens Creek site is a greenfield 

site. Historically, the site and vicinity was largely undisturbed and likely contained intact 

archaeological sites associated with the past 10,000 years of human settlement. Over time, the 

area has been disturbed by rural development and cleared for agricultural purposes. The 

majority of the land was cleared of native hardwood vegetation in the 1970’s for agricultural 

purposes. Today, much of the site is farmed and current uses include cropland and pasture 

land (STPNOC 2010a). 

Archaeological and/or architectural surveys conducted at the Allens Creek site were discussed 

in the 1974 final environmental statement (AEC 1974) for the proposed Allens Creek Nuclear 

Generating Station. The 1974 environmental statement identified four cemeteries, historic 

areas, and several significant archaeological sites in the Allens Creek area. Additionally, in that 

report, the AEC required that the applicant complete an investigation of selected archaeological 

sites in the vicinity of the plant and cooling reservoir before the start of construction activities 
Environmental Impacts of Alternatives 

February 2011 9-141 NUREG-1937 

that could impact the sites. Subsequently, applicant-sponsored investigations indicate that 

several mounds with human remains exist in the area. Should the site be developed, then 

consultation with the SHPO at the THC and Native American Tribes would help determine the 

significance of the mounds and any potential impacts the project would have on cultural 

resources. 

Seven historic properties listed on the National Register of Historic Places are found in Austin 

County. The closest listed properties to the Allens Creek site are the Church of the Guardian 

Angel, located in Wallis about 4 mi from the site and an ossuary located in the vicinity of Wallis. 

A Texas Historic Landmark, the Martin Allen Public House foundation and associated AllenJohnston cemetery, is about 1 mi from the Allens Creek site (STPNOC 2010a). Neither the 

Public House nor the cemetery is listed on the National Register. The project has the potential 

to affect resources through visual impacts from buildings and transmission lines. These impacts 

may result in significant alterations to the visual landscape within the geographic area of 

interest. 

Building and operating two nuclear generating units at the Allens Creek site would require 

approximately 800 ac for the main power plant site, approximately 52 ac for offsite 

transportation and pipeline corridors, and up to 9500 ac for the new, multi-use reservoir. In the 

event that the Allens Creek site was chosen for the proposed project, identification of cultural 

resources in these areas would be accomplished through cultural resource surveys and 

consultation with the SHPO, Tribes and interested parties. The results would be used in the site 

planning process to avoid cultural resources impacts. Because of the known and significant 

cultural resources that exist in the site area, the review team assumes that STPNOC would 

develop protective measures in a manner similar to those for the STP site. These procedures 

are detailed in STPNOC’s Addendum #5 to Procedure No. OPGP03-ZO-0025 Rev. 12 

(Unanticipated Discovery of Cultural Resources) (STPNOC 2008c); the procedures include 

notification of the SHPO at the THC and affected Tribe(s) or other parties depending on the 

nature of the find. 

Section 9.3.3.1 describes the transmission line corridors. Three new transmission lines would 

likely be needed to connect the Allens Creek site to the three closest 345-kV lines in the area 

(STPNOC 2010a). In the event that the Allens Creek site was chosen for the proposed project, 

the review team assumes that transmission corridor-related cultural resource surveys and 

procedures would be conducted in a manner similar to that for the STP site. In this context, the 

developer of transmission systems in the region, Oncor, would file an Environmental 

Assessment with the PUCT outlining practices to consider community, historic, and aesthetic 

values and prudent avoidance. During construction of such systems, should Oncor or its 

contractors encounter any archaeological artifacts or other cultural resources, work would halt 

immediately in the vicinity of the resource, the discovery would be reported to the THC, and 

Oncor would take action as directed by the THC. The established practice of conducting 
Environmental Impacts of Alternatives 

NUREG-1937 9-142 February 2011 

cultural and historic surveys as part of the Environmental Assessment and process for 

communicating with the THC for inadvertent discoveries ensures that offsite cultural and historic 

resources would be protected. 

Past actions in the geographic area of interest that have similarly impacted historic and cultural 

resources include rural development and agricultural development and activities associated with 

these land disturbing activities such as road development. Two current or planned projects, the 

Texas Independence Trail and the Allens Creek Reservoir, were identified in Table 9-12 that 

may contribute to cumulative impacts on historic and cultural resources in the geographic area 

of interest. 

Activities associated with building two nuclear units and supporting facilities that can potentially 

destabilize important attributes of historic and cultural resources include land clearing, 

excavation, and grading activities. Given the known cultural resources at the Allens Creek site, 

there would be unavoidable impacts to cultural resources due to site development activities. 

In addition, visual impacts from transmission lines may result in significant alterations to the 

visual landscape within the geographic area of interest. Given that historic setting and visual 

character are important elements associated with some known cultural resources at the Allens 

Creek site, visual impacts would be unavoidable. The review team assumes that the 

transmission system developer, i.e., Oncor, would continue to consider cultural and historic 

resources and associated aesthetic values in a manner consistent with the preparation of 

Environmental Assessments needed to support its filings before the PUCT before an approval is 

granted. 

Impacts on historic and cultural resources from operation of two new nuclear generating units at 

the Allens Creek site include those associated with the operation of new units and maintenance 

of transmission corridors. The review team assumes that the same procedures currently used 

by STPNOC would be used for onsite and offsite maintenance activities. Consequently, the 

incremental effects of the maintenance of transmission-line corridors and operation of the two 

new units and associated impacts on the cultural resources would be negligible for the physical 

APE and detectable but not destabilizing for the visual APE. 

The two projects identified in Table 9-12 that could contribute to the cumulative impacts on 

cultural resources are the Texas Independence Trail and the Allens Creek Reservoir, a 

municipal water supply reservoir. The Texas Independent Trail would not significantly affect 

historic and cultural resources in the geographic area of interest; the impacts would be limited to 

the visual APE and would be similar to those associated with the operation of two new units. 

Given the known cultural resources at the Allens Creek site, there would be significant adverse 

impacts to cultural resources in the geographic area of interest, including both the physical and 

visual APEs due to site development activities with regard to the Allens Creek Reservoir project. 
Environmental Impacts of Alternatives 

February 2011 9-143 NUREG-1937 

Cultural resources are non-renewable; therefore, the impact of destruction of cultural resources 

is cumulative. Based on the information provided by the applicant and the review team’s 

independent evaluation, the review team concludes that the cumulative impacts from building 

and operating two new nuclear generating units on the Allens Creek site and from other 

projects, particularly the planned co-located Allens Creek Reservoir, would be LARGE. The 

incremental contribution of building and operating the two new units would be a significant 

contributor to the cumulative impacts determination for the cultural resources known to exist 

within the physical and visual APEs and the geographic area of interest. 

9.3.3.8 Air Quality 

The following impact analysis includes impacts from building activities and operations. The 

analysis also considers other past, present, and reasonably foreseeable future actions that 

impact air quality, including other Federal and non-Federal projects listed in Table 9-12. The 

atmospheric emissions related to building and operating a nuclear power plant at the STP site in 

Matagorda County, Texas, are described in Chapters 4 and 5. The criteria pollutants were 

found to have a SMALL impact. In Chapter 7, the cumulative impacts of the criteria pollutants at 

the STP site were evaluated and also determined to be MODERATE principally because of a 

nearby major source; absent that source, the cumulative impacts would be SMALL. The 

geographic area of interest for the Allens Creek site is Austin County, which is in the 

Metropolitan Houston-Galveston Intrastate Air Quality Control Region (40 CFR 81.38). The 

emissions related to building and operating a nuclear power plant at the Allens Creek site would 

be similar to those at the STP site. The air quality attainment status for Austin County as set 

forth in 40 CFR 81.344 reflects the effects of past and present emissions from all pollutant 

sources in the region. Austin County is not out of attainment of any National Ambient Air Quality 

Standard. 

Reflecting on the projects listed in Table 9-12, the most significant is the W.A. Parish Electric 

Generating Station. Effluents from power plants such as this are typically released through 

stacks and with significant vertical velocity. Other industrial projects listed in Table 9-12 would 

have de minimis impacts. Given that these projects would be subject to institutional controls, it 

is unlikely that the air quality in the region would degrade to the extent that the region is in 

nonattainment of National Ambient Air Quality Standards. 

The air quality impact of Allens Creek site development would be local and temporary. The 

distance from building activities to the site boundary would be sufficient to generally avoid 

significant air quality impacts. There are no land uses or projects, including the aforementioned 

source, that would have emissions during site development that would, in combination with 

emissions from the Allens Creek site, result in degradation of air quality in the region. 

Releases from operation of two units at the Allens Creek site would be intermittent and made at 

low levels with little or no vertical velocity. The air quality impacts of the aforementioned source 
Environmental Impacts of Alternatives 

NUREG-1937 9-144 February 2011 

are included in the baseline air quality status. The cumulative impacts from emissions of 

effluents from the Allens Creek site and the aforementioned source would not be noticeable. 

The cumulative impacts of greenhouse gas emissions related to nuclear power are discussed in 

Section 7.6. The impacts of the emissions are not sensitive to location of the source. 

Consequently, the discussion in Section 7.6 is applicable to a nuclear power plant located at the 

Allens Creek site. The review team concludes that the national and worldwide cumulative 

impacts of greenhouse gas emissions are noticeable but not destabilizing. The review team 

further concludes that the cumulative impacts would be noticeable but not destabilizing, with or 

without the greenhouse gas emissions of the project at the Allens Creek site. 

Cumulative impacts to air quality resources are estimated based in the information provided by 

STPNOC and the review team’s independent evaluation. Other past, present and reasonably 

foreseeable future activities exist in the geographic areas of interest (local for criteria pollutants 

and global for greenhouse gas emissions) that could affect air quality resources. The 

cumulative impacts on criteria pollutants from emissions of effluents from the Allens Creek site, 

other projects, and the W.A. Parish Electric Generating Station would not be noticeable. The 

national and worldwide cumulative impacts of greenhouse gas emissions are noticeable but not 

destabilizing. The review team concludes that the cumulative impacts would be noticeable but 

not destabilizing, with or without the greenhouse gas emissions from the Allens Creek site. The 

review team concludes that cumulative impacts from other past, present, and reasonably 

foreseeable future actions on air quality resources in the geographic areas of interest would be 

SMALL for criteria pollutants and MODERATE for greenhouse gas emissions. The incremental 

contribution of impacts on air quality resources from building and operating two units at the 

Allens Creek site would be insignificant for both criteria pollutants and greenhouse gas 

emissions. 

9.3.3.9 Nonradiological Health 

The following impact analysis includes impacts from building activities and operations. The 

analysis also considers other past, present, and reasonably foreseeable future actions that 

impact nonradiological health, including other Federal and non-Federal projects listed in 

Table 9-12. The building-related activities that have the potential to impact the health of 

members of the public and workers include exposure to dust and vehicle exhaust, occupational 

injuries, noise, and the transport of construction materials and personnel to and from the site. 

The operation-related activities that have the potential to impact the health of members of the 

public and workers includes exposure to etiological agents, noise, EMFs, and impacts from the 

transport of workers to and from the site. For the analysis of nonradiological health impacts at 

the Allens Creek alternative site, the geographic area of interest is considered to include 

projects within a 5-mi radius from the site’s center based on the localized nature of the impacts. 

For impacts associated with transmission lines, the geographic area of interest is the 

transmission line corridor. 
Environmental Impacts of Alternatives 

February 2011 9-145 NUREG-1937 

Building Impacts 

Nonradiological health impacts to construction workers and members of the public from building 

two new nuclear units at the Allens Creek site would be similar to those evaluated in Section 4.8 

for the STP site. The impacts include noise, vehicle exhaust, dust, occupational injuries, and 

transportation accidents, injuries, and fatalities. Applicable Federal and State regulations on air 

quality and noise would be complied with during the site preparation and building phase. The 

incidence of construction worker accidents would not be expected to be different from the 

incidence of accidents estimated for STP. The Allens Creek site is located in a rural area and 

nonradiological health impacts from building would likely be negligible on the surrounding 

populations. The ER (STPNOC 2010a) indicated that transportation impacts could potentially 

be significant because the Allens Creek site is located in a rural area. Mitigation would be 

warranted, including constructing a new access road, and potentially widening existing 

roadways, installing traffic controls, and other measures designed to reduce traffic congestion. 

The additional injuries and fatalities from traffic accidents involving transportation of materials 

and personnel for building a new nuclear power plant at the Allens Creek site would be similar 

to those evaluated in Section 4.8.3 for the STP site and would represent a small fraction (less 

than 5 percent) of the total traffic fatalities in Austin County. 

There are no past or present actions in the geographic area of interest that would cumulatively 

impact nonradiological health in a similar way to those discussed for Allens Creek. Proposed 

future actions would include transmission line development and/or upgrading throughout the 

designated geographic area of interest, highway improvement projects, and future urbanization. 

These actions would likely result in nonradiological health impacts similar to those discussed 

above for the building of the Allens Creek site. 

Operational Impacts 

Nonradiological health impacts from operation of two new nuclear units on occupational health 

and members of the public at the Allens Creek site would be similar to those evaluated in 

Section 5.8 for the STP site. Occupational health impacts to workers (e.g., falls, electric shock 

or exposure to other hazards) at the Allens Creek site would likely be the same as those 

evaluated for workers at two new units at the STP site. Exposure to the public from water-borne 

etiological agents at the Allens Creek site would be similar to the types of exposures evaluated 

in Section 5.8.1, and the operation of the new units at the Allens Creek site would not likely lead 

to an increase in water-borne diseases in the vicinity. Noise and EMF exposure would be 

monitored and controlled in accordance with applicable OSHA regulations. Effects of EMF on 

human health would be controlled and minimized by conformance with NESC criteria and 

adherence to the standards for transmission systems regulated by the PUCT. Nonradiological 

impacts of traffic associated with the operations workforce would be less than the impacts 

during building. Mitigation measures taken during building to improve traffic flow would also 

minimize impacts during operation of a new unit. 
Environmental Impacts of Alternatives 

NUREG-1937 9-146 February 2011 

There are no past or present activities in the geographic areas of interest that would have 

nonradiological impacts to the public or workers similar to those discussed for the Allens Creek 

site. Proposed future actions that would impact nonradiological health in a similar way to 

operation activities at the Allens Creek site would include transmission line systems and future 

urbanization, which would both occur throughout the designated geographic areas of interest. 

The review team is also aware of the potential climate changes that could affect human health; 

a recent compilation of the state of the knowledge in this area (GCRP 2009) has been 

considered in the preparation of this EIS. Projected changes in the climate for the region 

include an increase in average temperature and decrease in precipitation, which may alter the 

presence of microorganisms and parasites in any reservoir that would be used. The review 

team did not identify anything that would alter its conclusion regarding the presence of 

etiological agents or change in the incidence of water-borne diseases. 

Summary 

Based on the information provided by STPNOC and the review team’s independent evaluation, 

the review team expects that nonradiological health impacts from building and operating two 

new units at the Allens Creek alternative site would be similar to the impacts evaluated for the 

STP site. While there are other past, present and future activities in the geographic area of 

interest that could affect nonradiological health in ways similar to the building and operation of 

two units at the Allens Creek site, those impacts would be localized and managed through 

adherence to existing regulatory requirements. The review team concludes, therefore, that the 

cumulative impacts would be SMALL. 

9.3.3.10 Radiological Impacts of Normal Operations 

The following impact analysis includes impacts from building activities and operations for two 

nuclear units at the Allens Creek alternative site. The analysis also considers other past, 

present, and reasonably foreseeable future actions associated with radiological impacts, 

including other Federal and non-Federal projects listed in Table 9-12. As described in Section 

9.3.3, Allens Creek is a greenfield site; there are currently no nuclear facilities on the site. The 

geographic area of interest is the area within a 50-mi radius of the Allens Creek site. There are 

no major facilities that result in regulated exposures to the public or biota within the 50-mi radius 

of the Allens Creek site. However, there are likely to be hospitals and industrial facilities within 

50 mi of the Allens Creek site that use radioactive materials. 

The radiological impacts of building and operating the proposed two ABWR units at the Allens 

Creek site include doses from direct radiation and liquid and gaseous radioactive effluents. 

These pathways would result in low doses to people and biota offsite that would be well below 

regulatory limits. These impacts are expected to be similar to those estimated for the STP site. 
Environmental Impacts of Alternatives 

February 2011 9-147 NUREG-1937 

The NRC staff concludes that the dose from direct radiation and effluents from hospitals and 

industrial facilities that use radioactive material would be an insignificant contribution to the 

cumulative impact around the Allens Creek site. This conclusion is based on data from the 

radiological environmental monitoring programs conducted around currently operating nuclear 

power plants. 

The cumulative radiological impacts from building and operating the two proposed ABWRs and 

other existing and planned projects and actions in the geographic area of interest around the 

Allens Creek site would be SMALL. 

9.3.3.11 Postulated Accidents 

The following impact analysis includes radiological impacts from postulated accidents from 

operations for two nuclear units at the Allens Creek alternative site. The analysis also considers 

other past, present, and reasonably foreseeable future actions that impact radiological health 

from postulated accidents, including other Federal and non-Federal projects and those projects 

listed in Table 9-12. As described in Section 9.3.3, Allens Creek is a greenfield site; there are 

currently no nuclear facilities on the site. The geographic area of interest considers all existing 

and proposed nuclear power plants that have the potential to increase the probability-weighted 

consequences (i.e., risks) from a severe accident at any location within 50 mi of the Allens 

Creek site. This includes the reactors at the STP Site. A site near Victoria has been identified 

as a potential reactor location. 

As described in Section 5.11.1, the staff concludes that the environmental consequences of 

DBAs at the STP site would be minimal for ABWRs. DBAs are addressed specifically to 

demonstrate that a reactor design is robust enough to meet NRC safety criteria. The ABWR 

design is independent of site conditions and the meteorology of the Allens Creek and STP sites 

are similar; therefore, the NRC staff concludes that the environmental consequences of DBAs at 

the Allens Creek site would be minimal. 

Because the meteorology, population distribution, and land use for the Allens Creek alternative 

site are expected to be similar to the proposed STP site, risks from a severe accident for an 

ABWR reactor located at the Allens Creek alternative site are expected to be similar to those 

analyzed for the proposed STP site. These risks for the proposed STP site are presented in 

Tables 5-18 and 5-19 and are well below the median value for current-generation reactors. In 

addition, estimates of average individual early fatality and latent cancer fatality risks are well 

below the Commission’s safety goals (51 FR 30028). For the existing plants within the 

geographic area of interest, STP Units 1 and 2, the Commission has determined that the 

probability-weighted consequences of severe accidents are small (10 CFR 51, Appendix B, 

Table B-1). It is expected that risks for any new reactors at the Victoria County Station site 

would be well below risks for current-generation reactors and meet the Commission’s safety 
Environmental Impacts of Alternatives 

NUREG-1937 9-148 February 2011 

goals. On this basis, the NRC staff concludes that the cumulative risks of severe accidents at 

any location within 50 mi of the Allens Creek alternative site would be SMALL. 

9.3.4 Trinity 2 

This section covers the review team’s evaluation of the potential environmental impacts of siting 

a new two-unit nuclear power plant at the Trinity 2 site in eastern Texas near the Trinity River. 

The site is located in a rural area of Freestone County approximately 10 mi northeast of Fairfield 

and 2.6 mi east of the existing Big Brown Power Plant. The water source for plant cooling and 

other plant uses would be the Trinity River and a new reservoir would be constructed. Trinity 2 

is a greenfield site not currently owned by the applicant (STPNOC 2010a). 

The following sections include a cumulative impact assessment conducted for each major 

resource area. The specific resources and components that could be affected by the 

incremental effects of the proposed action if implemented at the Trinity 2 site and other actions 

in the same geographic area were considered. This assessment includes the impacts of NRCauthorized construction and operations and impacts of preconstruction activities. Also included 

in the assessment are past, present and reasonably foreseeable future Federal, non-Federal, 

and private actions that could have meaningful cumulative impacts when considered together 

with the proposed action if implemented at the Trinity 2 site. Other actions and projects 

considered in this cumulative analysis are described in Table 9-16. 

The STP site is more than 200 mi from Trinity 2 and was therefore not included in this analysis. 

The only other nuclear power plant currently operating in Texas is Comanche Peak. The 

Comanche Peak plant is approximately 100 mi from Trinity 2 and therefore is also not included 

in the cumulative analysis. The proposed nuclear power plant in Victoria County is 

approximately the same distance as the STP site and was not included in the following analysis. 
Environmental Impacts of Alternatives 

February 2011 9-149 NUREG-1937 

Table 9-16. Past, Present, and Reasonably Foreseeable Future Projects and Other Actions 

Considered in the Cumulative Analysis of the Trinity 2 Alternative Site. 

Project Name Summary of Project 

Location 

(relative to Trinity 

2 site) Status 

Energy Projects 

Big Brown Power 

Plant (BBPP) 

Two 575-MW units. Burns 

lignite coal from local mines, 

supplemented by subbituminous coal delivered by 

train. Uses water from Lake 

Fairfield. 

Approximately 2.6 mi 

west of Trinity 2 

Operational(a)

Freestone Energy 

Center 

1035-MW natural gas plant on 

506 ac 

Approx 7 mi northwest 

of Trinity 2 

Operational(b)

Lakeside Energy 

Center 

Proposed 640-MW natural gas 

plant 

Approx12 mi northwest 

of Trinity 2 near 

Richland-Chambers 

Reservoir 

Proposed(c)

Limestone Electric 

Generating Station 

Expansion 

Currently comprised of two 

lignite/coal-fueled steam units, 

with a combined 1700 MW 

capacity. The proposed 

expansion project would add a 

third 744-MW unit. 

Approx 30 mi southsouthwest of Trinity 2 

near Jewett, Texas 

Units 1 and 2 

operational, Unit 3 

expected to begin 

operating in 2012(d)

Mining Projects 

Big Brown Lignite 

Coal Mine and 

Expansion 

Current mining consists of more 

than 20,000 ac of land mined in 

Freestone County. The owner 

of the Big Brown Mine, 

Luminant, plans to open the 

Turlington mine (10,397 ac) 

adjacent to and south of the 

existing Big Brown Mine. 

Approx 4 mi northwest 

of Trinity 2 

Operational.(e)

Turlington mine 

expected to begin 

operating in 2011(f)

Streetman Expanded 

Shale and Clay Plant 

Lightweight aggregate 

production facility 

Approx 21 mi west of 

Trinity 2 

Operational(g)

Transportation Projects 

Highway expansion Widening of US 79 About 18 mi southeast 

of Trinity 2 

Proposed but 

currently 

unfunded(h)

Highway expansion Widening of US 287 About 10 mi northeast 

of Trinity 2 

Proposed but 

currently 

unfunded(i)
Environmental Impacts of Alternatives 

NUREG-1937 9-150 February 2011 

Table 9-16. (contd)

Project Name Summary of Project 

Location 

(relative to Trinity 

2 site) Status 

Parks and Aquaculture Facilities 

Fairfield Lake State 

Park 

1460 ac outdoor recreation Approx 4 mi southwest 

of Trinity 2 

Operational(j)

Richland Creek 

Wildlife Management 

Area 

13,700 ac, created to 

compensate for habitat losses 

associated with the construction 

of Richland-Chambers 

Reservoir 

Approx 10 mi north of 

Trinity 2 

Operational(k)

Big Lake Bottom 

Wildlife Management 

Area 

2870 ac of the area are 

accessible and open for public 

use 

Approx 11 mi eastsoutheast of Trinity 2 Development likely 

limited within this 

park(l)

Gus Engeling Wildlife 

Management Area 

10,958 ac for wildlife 

management, research, and 

demonstration area for the Post 

Oak Savannah Ecoregion. Also 

used for hunting & other outdoor 

recreation. 

Approx16 mi northeast 

of Trinity 2 

Development likely 

limited within this 

park(m)

Other Actions/Projects: 

Tehuacana Reservoir 14,900-ac water supply 

reservoir 

Approx 10 mi westnorthwest of Trinity 2 Proposed(n)

Tennessee Colony 

Reservoir 

85,000-ac water supply and 

flood control reservoir 

Adjacent to Trinity 2 Proposed(o)

Coffield Correctional 

Institution 

Prison in operation since 1965, 

wastewater treatment plant 

Approx 8 mi eastsoutheast of Trinity 2 Operational(p)

Boyd Correctional 

Institution 

Prison in operation since 1992, 

wastewater treatment plant 

Approx. 15 mi westsouthwest of Trinity 2 Operational(q)

Nucor Steel Primary Metal Industries Approx 34 mi southsouthwest of Trinity 2 Operational(r)

 
Environmental Impacts of Alternatives 

February 2011 9-151 NUREG-1937 

Table 9-16. (contd)

Project Name Summary of Project 

Location 

(relative to Trinity 

2 site) Status 

Cayuga Independent 

School District 

Waste Water Treatment Plant Approx 9 mi northeast 

of Trinity 2 

Operational(s)

Future Urbanization Construction of housing units 

and associated commercial 

buildings; roads, bridges, and 

rail; construction of waterand/or wastewater- treatment 

and distribution facilities and 

associated pipelines, as 

described in local land-use 

planning documents. 

Throughout region. Construction would 

occur in the future, 

as described in 

state and local 

land-use planning 

documents 

Various hospitals and 

industrial facilities 

that use radioactive 

materials 

Medical and other isotopes Within 50 mi Operational in 

nearby cities and 

towns 

(a) Source: EPA 2009c 

(b) Source: Calpine 2009 

(c) Source: TCEQ 2009d 

(d) Source: NRG 2009 

(e) Source: EPA 2009d 

(f) Source: TRC 2010 

(g) Source: EPA 2009e 

(h) Source: TxDOT 2009a 

(i) Source: TxDOT 2009a 

(j) Source: TPWD 2009j 

(k) Source: TPWD 2009k 

(l) Source: TPWD 2009l 

(m) Source: TPWD 2009m 

(n) Source: TWDB 2010a 

(o) Source: TWDB 2006b 

(p) Source: EPA 2009f 

(q) Source: TDCJ 2009 

(r) Source: EPA 2009g 

(s) Source: EPA 2009h 
Environmental Impacts of Alternatives 

NUREG-1937 9-152 February 2011 

9.3.4.1 Land Use 

The following impact analysis includes impacts from building activities and operations. The 

analysis also considers past, present, and reasonably foreseeable future actions that impact 

land use, including other Federal and non-Federal projects and those projects listed in 

Table 9-16. For this analysis, the geographic area of interest for considering cumulative 

impacts is the 15-mi region surrounding the Trinity 2 site. This geographic area of interest 

includes the primary communities (e.g., Fairfield) that would be affected by the proposed project 

if it were located at the Trinity 2 site. The Trinity 2 site is a greenfield site located in an 

unincorporated area of Freestone County, Texas, 10.4 mi northeast of Fairfield. STPNOC 

estimates that approximately 18 percent of the Trinity 2 site is forested, 80 percent is in open 

land or grass lands, 1 percent is developed, and 1 percent is water resources (STPNOC 

2010a). There is no current zoning applicable to the site. The Trinity 2 site is not owned by the 

applicants. Acquisition of the site for a new power plant would involve land purchase from more 

than one landowner (STPNOC 2010a). 

The Trinity 2 site is not in the geographic area covered by the TCMP (TCMP 2009); therefore, 

the CZMA does not apply to this site. 

The Trinity 2 site is 2.6 mi east of the Big Brown Power Plant owned by Luminant Power 

(STPNOC 2010a). The Big Brown plant is a two-unit, 1150-MW, coal-fired plant (Luminant 

2009). The plant uses lignite coal mined near the plant (see Table 9-16) and also coal from the 

Powder River Basin in Wyoming. Continued mining operations would be expected to increase 

the amount of affected land near the Trinity 2 site. Cooling water for the Luminant plant comes 

from Fairfield Lake. Fairfield Lake has a surface area of approximately 2400 ac and was formed 

by a dam on Big Brown Creek (TSHA 2009g). Fairfield Lake State Park is located on the 

southern and southwestern shores of Fairfield Lake. 

If new nuclear generating units were built at the Trinity 2 site, the review team assumes that an 

onsite water storage reservoir for plant cooling would be built and that water would be diverted 

from the Trinity River. The land area affected by building two nuclear generating units at the 

Trinity 2 site would be approximately 800 ac for the main power plant site and up to 1700 ac for 

a new reservoir to be used for plant cooling (STPNOC 2010a). Land-use impacts would also 

occur to divert water to the plant and/or a reservoir and return discharge water to the Trinity 

River and for road and rail access. Most land-use impacts would occur during building, while 

plant operations would have minimal land-use impacts. The land-use impacts associated with 

building the plant and the reservoir at the Trinity 2 site would be noticeable, but not 

destabilizing. 
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February 2011 9-153 NUREG-1937 

Figure 9-13 shows the location of the Trinity 2 site and surrounding communities. There are no 

existing transmission corridors connecting directly to the Trinity 2 site. However, there are 

multiple 345-kV transmission lines connecting to the Big Brown Power Plant (STPNOC 2010a). 

One or more new transmission corridors would need to be created to connect the Trinity 2 site 

to these lines. The corridor(s) would pass through areas that are mostly rural with low 

population densities. Farmlands that would become part of a corridor could generally continue 

to be farmed. The land-use impacts of building one or more transmission corridors to serve the 

Trinity 2 site would be minimal. 

Within the 15-mi geographic area of interest, four reasonably foreseeable future projects 

(included in Table 9-16) have the potential to significantly affect cumulative land use. The first 

project would be the proposed Lakeside Energy Center. The Lakeside Energy Center would be 

a 640 MW(e) natural gas-fired power plant located on a 35 ac tract of land approximately 12 mi 

northwest of the Trinity 2 site. Construction and operations workers would likely be drawn from 

a wide area. If the proposed Lakeside Energy Center is constructed, one or more new 

transmission corridors would be needed to connect the plant to the grid. The second project 

would be the proposed Tehuacana Reservoir which would affect approximately 14,900 ac. The 

third project would be the proposed Tennessee Colony Reservoir which would impact 

approximately 85,000 ac adjacent to the Trinity 2 site. The fourth project would be the opening 

of the Turlington Mine to support the Big Brown Power Plant. The planned mine would affect 

approximately 10,400 ac. 

Future urbanization in the geographic area of interest, the continued operation of the Big Brown 

coal mine, the four proposed projects (see Table 9-16), and GCC could contribute to decreases 

in open lands, wetlands, and forested areas. Urbanization in the vicinity of the Trinity 2 site 

would alter important attributes of land use. Urbanization would reduce natural vegetation and 

open space, resulting in an overall decline in the extent and connectivity of wetlands, forests, 

and wildlife habitat. Continued operation of the Big Brown coal mine could include expansion of 

the mine at some point in the future. Potential expansion of the mine would result in a loss of 

open lands, forests, and wetlands. Construction of the four proposed projects (Lakeside Energy 

Center and associated transmission lines, the Tehuacana and Tennessee Colony reservoirs, 

and the Turlington Mine) would all also contribute to loss of open lands, forests, and wetlands. 

GCC could decrease precipitation, causing more frequent droughts when combined with 

increased evaporation in the geographic area of interest for the Trinity 2 site (GCRP 2009). 

Reduced water supply and increased temperatures could reduce crop yields and livestock 

productivity (GCRP 2009), which might change portions of agricultural and ranching land uses 

in the area of interest. However, existing parks, reserves, and managed areas would help 

preserve open lands, wetlands, and forested areas to the extent that they are not adversely 

affected by droughts. The proposed two reservoirs (Tehuacana and Tennessee Colony) may 

help ameliorate some adverse effects of droughts if the reservoirs are in operation soon 

enough. But these reservoirs would simultaneously cause land-use changes by inundating 
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Figure 9-13. Trinity 2 Alternative Site and 10-mi Radius
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February 2011 9-155 NUREG-1937 

large tracts of land. Urbanization trends, ongoing and proposed projects, and changes resulting 

from potential GCC could cause a shift in land use and, therefore, noticeably alter land uses in 

the geographic area of interest. 

Based on the information provided by STPNOC and the review team’s independent review, the 

review team concludes that the cumulative land-use impacts of constructing and operating two 

new nuclear generating units at the Trinity 2 site would be MODERATE. This conclusion 

reflects the substantial amount of land (up to 2500 ac onsite and additional offsite land for 

roads, a railroad spur, and pipelines) that would be needed for the proposed project if it were 

located at the Trinity 2 site, and the land-use impacts associated with the (1) proposed Lakeside 

Energy Center, (2) Tehuacana and Tennessee Colony Reservoirs, (3) Turlington Mine, and 

(4) transmission corridors that would be needed to serve the Trinity 2 and Lakeside Energy 

Center sites. Increased urbanization and potential effects of GCC could also noticeably 

contribute to this impact determination. Building and operating two new nuclear units at the 

Trinity 2 site would be a significant contributor to the MODERATE impact. 

9.3.4.2 Water Use and Quality 

The following impact analysis includes impacts from building activities and operations. The 

analysis also considers other past, present, and reasonably foreseeable future actions that 

impact water use and quality, including other Federal and non-Federal projects listed in 

Table 9-16. The Trinity 2 site is located in rural Freestone County in eastern Texas. Onsite 

drainages include Tehuacana Creek, Big Brown Creek, and Rock Springs Branch (see 

Figure 9-13), which all ultimately drain to the Trinity River. Development of this site for two 

nuclear units would require water from the Trinity River, and the building of a water storage 

reservoir on the Trinity 2 site. 

Geographic areas of interest are (1) for surface water the drainage basin of the Trinity River 

upstream and downstream of the intake and outfall structures, and the drainage basin of 

Tehuacana Creek upstream and downstream of the facility, and (2) for groundwater the aquifers 

upgradient and downgradient of the site. These regions are of interest because they represent 

the water resource potentially affected by siting the proposed project at the Trinity 2 site. 

As stated in Section 2.3.2, water use in Texas is regulated by the Texas Water Code. As 

established by Texas Water Code, surface water belongs to the State of Texas (Texas Water 

Code, Chapter 11, Section 11.021). The right to use surface waters of the State of Texas can 

be acquired in accordance with the provisions of the Texas Water Code, Chapter 11. In Texas, 

surface water is a commodity. Since the Trinity River Basin is currently heavily appropriated, 

future water users in this basin would likely only obtain surface water by purchasing or leasing 

existing appropriations. Regarding groundwater, Texas law has allowed landowners to pump 

the water beneath their property without consideration of impacts to adjacent property owners 

(NRC 2009). However, Chapter 36 of Texas Water Code authorized groundwater conservation 
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districts to help conserve groundwater supplies and issue groundwater use permits. Chapter 

36, Section 36.002, Ownership of Groundwater, states that ownership rights are recognized and 

that nothing in the code shall deprive or divest the landowners of their groundwater ownership 

rights, except as those rights may be limited or altered by rules promulgated by a district. Thus, 

groundwater conservation districts with their local constituency offer groundwater management 

options (NRC 2009). Existing projects in the State have appropriations to use water for their 

requirements. The review team expects that future projects, including the proposed units, if 

they were to be built and operated at the Trinity 2 site, would operate within the limits of these 

existing surface water and groundwater appropriations. 

As stated in Section 7.2.1, the GCRP has compiled the state of knowledge in climate change. 

This compilation has been considered in the preparation of this EIS. The projections for 

changes in temperature, precipitation, droughts, and increasing reliance on aquifers within the 

Trinity River Basin are similar to those in the Colorado River Basin (GCRP 2009). Such 

changes in climate would result in adaptations to both surface water and groundwater 

management practices and policies that are unknown at this time. 

There are currently 475 water rights owners in the Trinity River Basin, with total water rights of 

1,169,000 ac-ft/yr that are categorized as industrial, irrigation, or mining users (TCEQ 2009a). 

According to the TCEQ’s water availability maps, unappropriated flows in the Trinity River Basin 

for a perpetual water rights permit are available 25 to 50 percent of the time (TCEQ 2009b). 

The water availability maps do not show the quantity of available water for a new appropriation 

(TCEQ 2009b). The segment of the Trinity River near the Trinity 2 site appears on the State’s 

303(d) list as an impaired waterbody (TCEQ 2010b). 

The Texas Water Development Board, in the 2007 State Water Plan, has estimated that more 

than 1 million ac-ft of groundwater supplies would be available during 2010-2060 in the CarrizoWilcox Aquifer that is shared by 66 counties (TWDB 2006a). The Mid-East Texas Groundwater 

Conservation District (METGCD) in which Trinity 2 resides, has estimated an average historical 

use of approximately 2784 ac-ft/yr within Freestone County during 1980-2003 (METGCD 2009). 

The TWDB reported that wells in the Carrizo-Wilcox Aquifer support pumping rates from 500 to 

3000 gpm. 

Building Impacts

The review team assumed that no surface water would be used to build the units at the Trinity 2 

site so there would be no impact on surface water use. This assumption is consistent with the 

analysis done for the STP site and other alternative sites. 

The impacts on surface water quality from building potential units at the Trinity 2 alternative site 

would be limited to stormwater runoff that may enter nearby streams and rivers. Additionally, 

treated sanitary wastewater may be discharged to these streams and rivers. Building impacts 
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February 2011 9-157 NUREG-1937 

would be limited by the duration of these activities, and therefore, would be temporary. The 

State of Texas prohibits the unauthorized discharge of waste into or adjacent to water in the 

state (Texas Water Code, Chapter 26, Section 26.121). The discharge of waste may be 

authorized under a general or individual permit (Texas Water Code, Chapter 26). These 

permits may require an SWPPP that includes BMPs appropriate for the site (TCEQ 2003; 

STPNOC 2010a). Implementation of BMPs should minimize impacts to wetlands and surfacewater bodies near the Trinity 2 alternative site. Therefore, the water quality impacts on wetlands 

and water bodies related to building the proposed units at the Trinity 2 alternative site would be 

temporary and minimal. 

The review team assumes that the groundwater use for building activities at the Trinity 2 site 

would be identical to the proposed groundwater use for the STP site (STPNOC 2009a). 

Monthly normalized groundwater use for the STP site ranges up to 491 gpm (792 ac-ft/yr) (see 

Table 3-4). STPNOC stated that groundwater would be used for potable and sanitary use, 

concrete batch plant operation, concrete curing, dust suppression and cleaning, placement of 

engineered backfill, and piping hydrotests and flushing (STPNOC 2010a). 

The review team concludes that the potential groundwater use at the Trinity 2 alternative site 

during building activities would not be unreasonable because the site would utilize units similar 

to those proposed for the STP site and the building activities would also be similar. 

The Trinity 2 alternative site is located in Region C, GMA 12, and the METGCD. Since 

publication of the draft EIS, GMA 12 adopted desired future conditions for the Carrizo-Wilcox 

Aquifer in Freestone County (TWDB 2010b, POSGCD 2010), which is the source of 

groundwater that would be used by STPNOC. A draft groundwater availability modeling report 

was produced and is available on the TWDB website (Oliver 2010). The draft reports future 

groundwater use to be somewhat higher than historic values, and draft managed available 

groundwater values are somewhat less than the future use levels. The Carrizo-Wilcox Aquifer 

outcrops in much of Freestone County and therefore receives recharge in the area. Based on 

the available information, the review team determined that the groundwater that would be used 

for building the proposed units at the Trinity 2 alternative site would be approximately 28 percent 

of the average historical groundwater use from the Carrizo-Wilcox Aquifer in Freestone County. 

Groundwater use during building of the proposed units represents approximately 15 percent of 

the future groundwater use in Freestone County and approximately 17 percent of the draft 

managed available groundwater level (Oliver 2010). The final managed available groundwater 

resource level will be determined at a future time by the METGCD in cooperation with the 

TWDB (METGCD 2009). 

The review team determined, based on available information and groundwater source options 

that it is possible that there is sufficient groundwater available in the Carrizo-Wilcox aquifer to 

provide the groundwater needed to build the potential units at the Trinity 2 alternative site. For 

example, the METGCD is developing an estimate of the managed available groundwater in the 
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NUREG-1937 9-158 February 2011 

district and may find sufficient groundwater resource to allow expanded use of the aquifer. 

Based on standard geohydrologic practice, the review team concludes that the drawdown in the 

Carrizo-Wilcox Aquifer could be managed for groundwater pumping during building activities 

using an appropriately designed well system. Accordingly, the review team concludes that the 

impact of groundwater use for building the potential units at the Trinity 2 site could be minimal. 

However, if a new groundwater use permit is issued, and the managed available groundwater 

resource is not sufficient, then the impact would be noticeable but not destabilizing because 

pumping from the aquifer would be temporary and limited to the building period. 

While building the potential units at the Trinity 2 alternative site, impacts to groundwater quality 

may occur from leaching of spilled effluents into the subsurface. Within Freestone County, wells 

completed within the Carrizo-Wilcox Aquifer yield groundwater with TDS levels of less than 

500 mg/L (TWDB 2006a, Dutton et al 2003). STPNOC stated that BMPs would be in place 

during building activities and therefore the review team concludes that any spills would be 

quickly detected and remediated. In addition groundwater impacts would be limited to the 

duration of these activities, and therefore, would be temporary. Because any spills related to 

building activities would be quickly remediated through the use of BMPs, and the activities 

would be temporary, the review team concludes that the groundwater-quality impacts from 

building at the Trinity 2 site would be minimal. 

Operational Impacts

STPNOC estimated that a two-unit plant, operated at the Trinity 2 alternative site using a 

closed-cycle cooling system that would employ a cooling water reservoir, would consume a 

maximum of 50,000 ac-ft of water per year. STPNOC has identified the Trinity River as the 

source of the cooling water at the Trinity 2 alternative site. STPNOC currently does not own the 

necessary water rights. STPNOC would need to acquire existing Trinity River water rights that 

are currently being used for industrial, irrigation, and mining use. Therefore, based on the 

1,169,000 ac-ft/yr of water rights held on the Trinity River by 475 water right owners, STPNOC 

would need to acquire a minimum of 4.3 percent of these water rights. 

According to TCEQ staff, acquired water rights would have to be aggregated at a single point of 

diversion which may lead to concerns regarding instream flow to maintain water quality and 

habitat (NRC 2009). The TCEQ staff stated that, under current Texas laws, the acquisition and 

aggregation process would need to consider the quantity and location of all water rights and the 

instream flow needs that may be affected by transfer of these water rights. Because STPNOC 

has not identified the particular water rights that may be acquired, it is difficult to determine if 

any are suitable for acquisition. However, the review team concluded that the TCEQ permitting 

process would require STPNOC to acquire water rights in sufficient quantity, at appropriate 

locations, and of appropriate type within the Trinity River Basin such that this reallocation of 

water rights does not adversely affect surface water use and quality in the basin. As such, 

based upon the water rights that would need to be reallocated to accommodate the facility at the 
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February 2011 9-159 NUREG-1937 

Trinity 2 site, the review team determined that the operational surface water use impact of the 

proposed units at the Trinity 2 alternative site would be noticeable but not destabilizing. 

During the operation of the proposed units at the Trinity 2 alternative site, impacts to surface 

water quality could result from stormwater runoff, discharges of treated sanitary and other 

wastewater, blowdown from service water cooling towers, and periodic discharges from the 

cooling water reservoir into the Trinity River. The State of Texas may require STPNOC to 

obtain a general or individual permit for the discharge of stormwater (Texas Water Code, 

Chapter 26). These permits may require an SWPPP that includes BMPs appropriate for the site 

(TCEQ 2001; STPNOC 2010a). Any discharges of sanitary and other wastewaters or cooling 

water reservoir discharges would be controlled by the State of Texas under a TPDES permit. 

The State of Texas limits the quantity and quality of discharges to surface water bodies while 

accounting for concurrent discharge and quality conditions within the surface water body. 

These permit conditions would also account for designated uses of the receiving surface water 

body and comply with the Clean Water Act. Such permits are designed to protect water quality. 

The review team expects that the conditions placed on operations of the proposed units at the 

Trinity 2 site would be similar to those currently placed on the existing facilities at the STP site 

(Section 5.2.3.1). Therefore, the review team concluded that the operational impact on surface 

water quality of the receiving water body would be minimal because the discharge quantity and 

quality would be controlled. 

The proposed Units 3 and 4 would use approximately 975 gpm (1572 ac-ft/yr) of groundwater 

during normal operations and approximately 3434 gpm (5538 ac-ft/yr) during maximum demand 

conditions (STPNOC 2010a). STPNOC stated that the expected groundwater use for Units 3 

and 4 are assumed to also apply to alternative sites. However, for maximum operation demand 

periods, STPNOC assumes that a temporary increase in the rate of surface water use would be 

available (STPNOC 2009a). 

The review team concludes that the potential groundwater use at the Trinity 2 alternative site 

during operations would not be unreasonable because the alternative site would utilize units 

similar to those proposed for the STP site. 

As stated above, since publication of the draft EIS the desired future conditions for the CarrizoWilcox Aquifer have been adopted; however, only draft levels for the managed available 

groundwater resource have been provided (TWDB 2010b; POSGCD 2010; Oliver 2010). The 

Texas Water Development Board, in the 2007 State Water Plan, estimated that more than 

1 million ac-ft/yr of groundwater supplies would be available during 2010-2060 in the CarrizoWilcox Aquifer that is shared by 66 counties (TWDB 2006a). The TWDB also reported that 

wells in the Carrizo-Wilcox Aquifer support pumping rates from 500 to 3000 gpm. The 

METGCD determined that average historical use of groundwater in Freestone County between 

1984 and 2003 was approximately 2784 ac-ft/yr. The normal operation groundwater use of 

975 gpm (1572 ac-ft/yr) represents 56 percent of the county’s historical usage. Groundwater 
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NUREG-1937 9-160 February 2011 

use during operation of the proposed units represents approximately 31 percent of the future 

groundwater use and approximately 33 percent of the draft managed available groundwater 

level in Freestone County (Oliver 2010). 

STPNOC stated that access to groundwater production from existing wells would be sought 

before requesting new or future groundwater capacity, and that water could be imported 

primarily for potable water use and thereby reduce groundwater demand (STPNOC 2009a). 

Thus, less new groundwater may be needed for operations at the Trinity 2 site. However, it is 

possible that units operating at the Trinity 2 site would use a large fraction of the available 

groundwater resource for operations. Based on standard hydrogeologic practice, the review 

team determined that the amount of drawdown in the Carrizo-Wilcox Aquifer from groundwater 

pumping during operation could be limited by installing multiple, appropriately-spaced wells 

because groundwater could be withdrawn from a large area resulting in smaller drawdown. 

Because of the level of groundwater resource use and the potential for drawdown to occur over 

the operational period of the facility, the review team concludes that the impact of operational 

groundwater use at the Trinity 2 site would be noticeable. However, based on available 

information on the aquifer, and the authority of groundwater conservation districts to manage 

and permit groundwater resources (Texas Water Code, Chapter 36), the review team expects 

that the impact to the groundwater resource under a groundwater use permit issued by the 

applicable groundwater conservation district would not destabilize the groundwater resource. 

During the operation of a potential plant at the Trinity 2 alternative site, impacts to groundwater 

quality could result from potential spills. Spills that might affect the quality of groundwater would 

be prevented and mitigated by BMPs. During operation of the potential units at the Trinity 2 

alternative site, some drawdown of the Carrizo-Wilcox Aquifer would be expected; however, the 

aquifer yields fresh groundwater with TDS levels of less than 500 mg/L (Dutton et al. 2003, 

TWDB 2006a). Because any spills would be quickly detected and remediated through the use 

of BMPs, and no intentional discharge to groundwater should occur, the review team concludes 

that the groundwater-quality impacts from operation of two nuclear units at the Trinity 2 site 

would be minimal. 

Cumulative Impacts

In addition to water use and water quality impacts from building and operations activities, 

cumulative analysis considers past, present, and reasonably foreseeable future actions that 

impact the same environmental resources. For the cumulative analysis of impacts on surface 

water, the geographic area of interest for the Trinity 2 site is considered to be the drainage basin 

of the Trinity River upstream and downstream of intake and discharge structures, and the 

drainage basin of Tehuacana Creek upstream and downstream of the Trinity 2 site because this 

is the resource that would be affected by the Trinity 2 project. For groundwater, the geographic 

areas of interest for cumulative analysis of the Trinity 2 site are aquifers underlying the site 

upgradient and downgradient of the site. 
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Water supply in the Trinity River Basin could change with implementation of potential water 

management strategies (e.g., Lake Tehuacana and Tennessee Colony Lake; Table 9-16). Key 

actions that have past, present and future potential impacts to water supply and water quality in 

the Trinity River basin include the existing Big Brown Power Plant, Freestone Energy Center, 

and Big Brown Lignite Coal Mine and Expansion (Table 9-16). Key actions that would have 

future potential impacts to water supply and water quality include the planned Lakeside Energy 

Center, Limestone 3 Electric Generating Station Expansion Project (Table 9-16), and the 

cooling water reservoir and/or water storage reservoir required for operation of the Trinity 2 site. 

The Lakeside Energy Center would use a new 640-MW gas-fired unit that may use water for 

cooling purposes. Unit 3 at the Limestone site would generate 744 MW and would use dry 

cooling, which would substantially reduce water consumption. 

Cumulative Water Use

The only surface-water-use impacts of building and operating a nuclear power plant at this site 

would be the water demands occurring during operation. The projected consumptive surface 

water use of the two potential units at the Trinity 2 site is expected to be about 50,000 ac-ft/yr or 

4.3 percent of the total basin water rights (i.e., 1,169,000 ac-ft/yr), held by 475 water right 

owners in the Trinity River Basin. Future potential water use by other actions in the Trinity River 

Basin (e.g., Lakeside Energy Center and Limestone 3 Electric Generating Station Expansion 

Project) would also increase consumptive demand. Because the total rated power output of 

these power plants is smaller than that of the two proposed units, the review team concludes 

that the potential water use of these projects would likely be smaller than that for the two 

proposed nuclear units if they were to be operated at the Trinity 2 site; therefore the combined 

future water use would likely still be a relatively small fraction of the current water rights in the 

basin. Therefore, the review team concludes that the impact of these projects on the region’s 

surface water use would be noticeable but not destabilizing. 

Increases in consumptive use of water in the Trinity River drainage is anticipated in the future, 

however, the impacts of the other projects listed in Table 9-16 would have little or no impact on 

surface water use. 

The review team is also aware of the potential for GCC affecting the water resources available 

for closed-cycle cooling and the impact of reactor operations on water resources for other users. 

The impact of GCC on regional water resources is not precisely known, however it may result in 

decreases in precipitation and increases in average temperature (GCRP 2009). Such changes 

could further stress regional water resources. However, the impacts related to GCC would be 

similar for all the alternative sites 

Historically, the waters of the Trinity River Basin have been used extensively. The region has a 

planning, allocation, and development system in place to manage its limited surface water 

supplies. These efforts are described in the Regional and State Water Plans (Region C 
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Regional Water Planning Group [RCRWPG]) (TWDB 2006a, b). As stated above, operation of 

the proposed units on the Trinity 2 site would result in a noticeable but not destabilizing impact 

to the surface water use in the region. Future projects in the region would also result in 

noticeable but not destabilizing impacts on surface water use in the region. Therefore, the 

review team concludes that cumulative impacts to surface water use would be MODERATE. 

Building and operating the proposed plant at the Trinity 2 site would be a significant contributor 

to these water-use impacts. 

Groundwater-use impacts at this site are characterized by the groundwater demand at the STP 

site, and those use levels are 491 gpm (792 ac-ft/yr) during building, a normal operation 

demand of 975 gpm (1572 ac-ft/yr), and a maximum operation demand of 3434 gpm 

(5538 ac-ft/yr) (STPNOC 2010a). However, for maximum operation demand periods, STPNOC 

assumes that a temporary increase in the rate of surface water use would be available 

(STPNOC 2009a). During building and normal operation, the possibilities exist that STPNOC 

could (1) use a new groundwater permit and associated wells in the Carrizo-Wilcox aquifer, (2) 

acquire existing groundwater production from wells in the vicinity of the plant, and (3) use of 

imported water primarily for potable use onsite to reduce groundwater-use requirements 

(STPNOC 2009a). With regard to the groundwater resource used by all other past and present 

projects, the average use of the Carrizo-Wilcox aquifer in Freestone County is approximately 

2784 ac-ft/yr. Normal operation demand for the proposed units, if they were placed at the 

Trinity 2 site, would represent a 56 percent increase in groundwater use within the CarrizoWilcox aquifer in Freestone County. The review team concludes this is a significant increase in 

use of the groundwater resource for future projects. 

As indicated above, groundwater would be used during the building and operation of two 

nuclear units at the Trinity 2 site. Because of the alternatives available to supply groundwater, 

(i.e., new, acquired, imported), it is possible that new groundwater demand would be reduced. 

However, the METGCD is now working with the TWDB to establish the managed available 

groundwater quantity for the Carrizo-Wilcox aquifer. Accordingly, the review team concludes 

that based on available information on the aquifer, and the authority of groundwater 

conservation districts to manage and permit groundwater resources (Texas Water Code, 

Chapter 36), the impact to the groundwater resource under a groundwater use permit issued by 

the applicable groundwater conservation district would not destabilize the groundwater 

resource. Therefore, the review team concludes that cumulative impacts to groundwater use 

would be MODERATE. Building and operating the proposed units at the Trinity 2 site would be 

a significant contributor to this groundwater-use impact because the implied use of groundwater 

would exceed the current estimate of historical groundwater use from the Carrizo-Wilcox Aquifer 

in Freestone County by approximately 28 percent for building and 56 percent for operating the 

proposed units. Groundwater use compared to the draft managed available groundwater 

estimates for Freestone County would represent approximately 17 percent for building and 
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February 2011 9-163 NUREG-1937 

approximately 33 percent for operating the proposed units (Oliver 2010). The impacts of other 

projects listed in Table 9-16 would have little or no impact on groundwater use. 

Cumulative Water Quality

Point and nonpoint sources in the river basin have affected the water quality of the Trinity River. 

The segment of the Trinity River to which the proposed units, if they were to be operated at the 

Trinity 2 site, would discharge effluent, appears on the State’s 303(d) list as an impaired 

waterbody (TCEQ 2010b). Water quality information presented above for the impacts of 

building and operating the new units at the Trinity 2 site would also apply to evaluation of 

cumulative impacts. The State of Texas may require an applicant to obtain a general or 

individual permit for discharge of stormwater (Texas Water Code, Chapter 26). These permits 

may require an SWPPP that includes BMPs appropriate for the site (TCEQ 2001, 2003; 

STPNOC 2010a). The State of Texas would also issue TPDES permits for the discharge of 

sanitary and other wastewaters including blowdown from service water cooling towers and 

cooling water reservoir discharges before operation of the units at the Trinity 2 site. Effluent 

discharges through a TPDES-permitted outfall, such as those from the Big Brown Power Plant, 

Freestone Energy Center, and Limestone Electric Generating Station, are required to comply 

with the Clean Water Act. Such permits are designed to protect water quality. Because 

historical discharges to the Trinity River have resulted in impairment of the segment near the 

Trinity 2 site, the review team concludes that the cumulative impact on surface water quality of 

the receiving water body would be MODERATE. Building and operating the proposed units at 

the Trinity 2 site would not be a significant contributor to these surface water quality impacts, 

because industrial and wastewater discharges from the proposed units would comply with 

TPDES permit limitations. The impacts of other projects listed in Table 9-16 would have little or 

no impact on surface water quality. 

The review team also concludes that with the implementation of BMPs, the impacts to 

groundwater quality from building and operating two new nuclear units at the Trinity 2 site would 

likely be minimal. The individual impacts from other projects listed in Table 9-16 would have 

little or no impact on regional groundwater quality because of the local nature of groundwater 

withdrawals and their associated impacts. Therefore, the cumulative impact on groundwater 

quality would be SMALL. 

9.3.4.3 Terrestrial and Wetland Resources 

The following impact analysis includes impacts from building activities and operations. The 

analysis also considers other past, present, and reasonably foreseeable future actions that 

impact terrestrial and wetland resources, including other Federal and non-Federal projects listed 

in Table 9-16. For the analysis of terrestrial ecological impacts at the Trinity 2 site, the 

geographic area of interest is the intersection of the East Central Plains ecoregion and the 
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Trinity-Lower Tehuacana watershed (Figure 9-14). This region is expected to encompass the 

ecologically relevant landscape features and species. 

The Trinity 2 site is a greenfield site located 2.5 mi west and 5 mi south of the Trinity River. The 

site is in the Blackland Prairies subprovince of the Gulf Coast Plains. The blacklands have a 

gentle undulating surface that has been cleared of most natural vegetation for the cultivation of 

crops (UT 1996). The soils of the blacklands are chalks and marls that have weathered to 

deep, fertile clay soils. Pre-settlement conditions were that of a true prairie grassland 

community dominated by a diverse assortment of perennial and annual grasses and forbs, with 

sparsely scattered trees or mottes of oaks (Quercus sp.) on the uplands (TPWD 2009a). 

Forested or wooded areas were restricted to bottomlands along major rivers and streams, 

ravines, protected areas, or on certain soil types. Trees such as pecan (Carya illinoinensis), 

cedar elm (Ulmus crassifolia), cottonwoods (Populus sp.), various oaks, and hackberry 

(Celtis sp.) dotted the landscape (TPWD 2009b). The dominant grass was the little bluestem 

(Schizachyrium scoparium); other grasses included the big bluestem (Andropogon gerardii), 

Indiangrass (Sorghastrum sp.), eastern gamagrass (Tripsacum dactyloides), switchgrass 

(Panicum virgatum), and sideoats grama (Bouteloua curtipendula). 

Currently in the region surrounding the Trinity 2 site, there is a mixture of post oak woods, 

improved pasture, and rangeland (STPNOC 2010a). There is also a surface lignite mining 

operation to the west. Onsite drainages include Tehuacana Creek, Big Brown Creek, and Rock 

Springs Branch. Big Brown Creek is dammed in its middle reaches to form Fairfield Lake; it 

flows into Tehucana Creek. Big Brown Creek crosses rolling prairie with local shallow 

depressions, surfaced by clay and sandy loams that support hardwoods, mesquite, conifers, 

and grasses. The area is used primarily for dryland farming. Tehuacana Creek flows into the 

Trinity River and passes through terrain similar to Big Brown Creek. The area supports watertolerant hardwoods, conifers, and grasses (STPNOC 2010a). 

The total acreage for all temporary and permanent impacts at the Trinity 2 site would be 

approximately 800 ac for the plant site and 1700 ac for the reservoir. Permanent impacts 

associated with building two new nuclear units would include approximately 150 ac for each unit 

(300 ac total) and a new 1700-ac reservoir for cooling water for the plant (STPNOC 2010a). 

While specific habitat acreages have not been determined for the site, Table 9-17 gives 

approximate acreages by land cover class for areas expected to receive permanent impacts. 

No assessment was made for land cover classes expected to receive temporary impacts 

(STPNOC 2010a). 
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Figure 9-14. Geographic Area of Analysis of Cumulative Impacts to Terrestrial Resources for 

the Trinity 2 Site in Freestone County
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Table 9-17. Estimated Land Cover Classes for Approximately 2000 ac of the 2500-ac Trinity 2 

Site. 

Land Cover Class Plant (ac) Reservoir (ac) 

Forested (includes 80 ac of high-quality forested wetlands) 160 190 

Open land/grasslands 140 1460 

Developed areas (roads, drill pads) 30 

Water resources/freshwater ponds 20 

Source: STPNOC 2010a 

Note: Estimates are for areas receiving permanent impacts and are based on Google Earth Imagery 

No digitized wetland maps are available for the site area, so wetland acreage was estimated 

using United States Geological Survey (USGS) quadrangle maps that encompass the site 

(STPNOC 2010a). Within the 2000-ac area for the Trinity 2 site receiving permanent impacts, 

wetlands appear to be limited to the northern portion. These wetlands include several highquality forested wetlands (80 ac total) with several small freshwater ponds (20 ac total). 

Approximately 15 of the 100 ac appear to be located in the area where the plant would be 

located; 10 ac of the 15 ac are high quality forested wetlands. The remaining wetland areas fall 

within the footprint of the reservoir. 

There are numerous wildlife areas located near the Trinity 2 site (STPNOC 2010a, TPWD 

2009c) including the Fairfield Lake State Park, 4-mi southwest of the site, the Richland Creek 

WMA approximately 10 mi north of the site, the Gus Engeling WMA, approximately 16 mi 

northeast of the site, and the Big Lake Bottom WMA 11 mi east-southeast of the site. The 

woods at the Fairfield Lake State Park include oak, hickory, cedar elm, dogwood, and redbud, 

and mark the transition zone between pine forests to the east and the prairie grasslands to the 

north and west (TPWD 2009c). Wildlife found at the park include osprey, bald eagles 

(November through February), white-tailed deer, raccoons, foxes, beaver, squirrels, and 

armadillos. The Richland Creek WMA supports a wide variety of bottomland and wetland 

dependent wildlife and vegetation communities which serves as nesting and brood rearing 

habitat for many species of neotropical birds (TPWD 2009c). In addition, the area has 

numerous marshes and sloughs which provide habitat for migrating and wintering waterfowl, 

wading and shore birds. The Gus Engeling WMA is comprised of 2000 ac of hardwood 

bottomland floodplain and almost 500 ac of natural watercourse, 350 ac of wetlands, and nearly 

300 ac of sphagnum moss bogs (TPWD 2009c). There are two Ecologically Significant River 

and Stream Segments near the Trinity 2 site: the Trinity River from the Freestone/Anderson/ 

Leon County line upstream to the Anderson/Henderson County line, and Buffalo Creek, from the 

confluence with Alligator Creek in Freestone County upstream to State Route 164 in Freestone 

County (TPWD 2010). In addition, drainage in the area feeds Catfish Creek, a tributary of the 

Trinity River. Eight mi of the creek have been designated as a “Natural National Landmark” by 

the U.S. Department of Interior (NPS 2009). Currently wildlife in the Gus Engeling WMA 

comprises nearly 40 species of mammals, 156 species of birds, 54 species of reptiles and 
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amphibians, and 900 plant species. More than 90 percent of the Big Lake Bottom WMA is 

bottomland habitat of mature hardwood timber with more than 450 plant species (TPWD 2009c). 

Wildlife species include white-tailed deer, feral hog, ducks, mourning dove, fox squirrel, gray 

squirrel, raccoon, skunk, armadillo, coyote, grey fox, plus numerous species of reptiles and 

migratory birds. 

Important Species 

A range of recreationally important wildlife species occur at the site including white-tailed deer 

(Odocoileus virginianus), mourning dove (Zenaida macroura), and northern bobwhite (Colinus 

virginianus) on the uplands, and eastern fox squirrel (Sciurus niger) along stream bottoms 

(STPNOC 2010a). The Tehuacana Creek area, north of the Trinity 2 site, contains excellent 

deer and wild turkey habitat (STPNOC 2009a). Generally these species are habitat generalists 

(NatureServe 2009a), although lack of nesting and brood rearing habitats for the turkey and 

northern bobwhite have led to their decline (TPWD 2009e). The site lies within the Central 

Flyway of Texas (STPNOC 2009a) and provides habitat for rest and forage opportunities during 

migration. 

Up to eight bat species living in eastern Texas, can occur in Freestone County (Davis and 

Schmidly 1994; STPNOC 2009a). Some are mostly year-round residents (i.e., non-migratory), 

such as the big brown bat (Eptesicus fuscus), the eastern pipistrelle (Perimyotis subflavus), 

southeastern myotis (Myotis austroriparius), and evening bat (Nycticeius humeralis). Migratory 

bats that could occur at the site include the hoary bat (Lasiurus cinereus), the silver-haired bat 

(Lasionycteris noctivagans), the eastern red bat (Lasiurus borealis), and the Mexican free-tailed 

bat (Tadarida brasiliensis). The Mexican free-tailed bat is either migratory or non-migratory 

depending on where it resides; the migratory status of bats occurring in Freestone County is 

currently unknown (STPNOC 2009a). 

No site-specific surveys have been conducted for threatened and endangered species at the 

Trinity 2 site. The following list for Freestone County (Table 9-18) is from the Texas Parks and 

Wildlife Threatened and Endangered Species by County website (TPWD 2009f) and the 

U.S. Fish & Wildlife Service Ecological Service threatened and endangered species for the 

Southwest region website (FWS 2009a). The list includes four species on the Federalendangered list (FWS 2009a), and an additional ten species on the State-endangered and 

threatened species list (TPWD 2009f). 
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Table 9-18. Federally and State-listed Threatened and Endangered Species in Freestone 

County, Texas 

Group Common Name Scientific Name 

Federal 

Status 

State 

Status 

Plants Large-fruited sand-verbena Abronia macrocarpa E E 

Navasota ladies'-tresses Spiranthes parksii E E 

Amphibian

s 

Houston toad Bufo houstonensis E 

Reptiles Alligator snapping turtle Macrochelys temminckii T 

Texas horned lizard Phrynosoma cornutum T 

Timber/canebrake rattlesnake Crotalus horridus T 

Birds American peregrine falcon Falco peregrinus anatum T 

Bachman's sparrow Peucaea aestivalis T 

Bald eagle Haliaeetus leucocephalus T 

Interior least tern Sternula antillarum athalassos E E 

Piping plover Charadrius melodus T 

Whooping crane Grus americana E E 

Wood stork Mycteria americana T 

Mammals Red wolf Canis rufus E 

Sources: FWS 2009a; TPWD 2009f 

T = threatened; E = endangered 

Large-fruited sand-verbena

Large-fruited sand-verbena (Abronia macrocarpa) is a Federally and State-listed endangered 

species (FWS 2009a; TPWD 2009f). This plant lives in sandy openings in post oak-grassland 

mosaic vegetation type (NatureServe 2009b). It is sometimes found on actively blowing sand 

dunes. The species can temporarily dominate bare sand areas during the spring. This plant is 

distributed in Freestone and two other counties in Texas (TPWD 2009g). 

Navasota ladies’-tresses

The orchid, Navasota ladies’-tresses (Spiranthes parksii), is a Federally and State-listed 

endangered species (FWS 2009a; TPWD 2009f). This plant is endemic to the Oak Woodlands 

and Prairies region of east-central Texas (TPWD 2009g). It occurs primarily in seasonally moist 

soils along open wooded margins of creeks, drainages, and intermittent tributaries of the Brazos 

and Navasota rivers. Once thought to be extremely rare, it is now known to be locally common 

in parts of its range which includes Freestone County. 
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Houston toad

The Houston toad (Bufo houstonensis) is a State-listed endangered species (TPWD 2009f). It 

lives primarily on land and burrows into sand for protection from cold weather in the winter and 

from hot, dry conditions in the summer. The toads are found in areas with loose, deep sand 

supporting woodland savannah and in proximity to still or flowing waters for breeding (TPWD 

2009g). The toads have been recorded in Freestone County and in the Trinity River watershed 

(NatureServe 2009b). 

Alligator snapping turtle

The alligator snapping turtle (Macrochelys temminckii) is a State-listed threatened species 

(TPWD 2009f). It is found in slow-moving, deep water of rivers, sloughs, oxbows, and canals or 

lakes associated with rivers; also swamps, and ponds near rivers, and shallow creeks that are 

tributary to occupied rivers (NatureServe 2009b). It usually occurs in water with mud bottoms 

and abundant aquatic vegetation; it may migrate several miles along rivers (TPWD 2009g). 

Turtles are rarely found out of the water except when nesting. The turtles have been recorded 

in the Upper and Lower Trinity watersheds (NatureServe 2009b). 

Texas horned lizard 

The Texas horned lizard (Phrynosoma cornutum) is a State-listed threatened species (TPWD 

2009f). It can be found in arid and semiarid habitats in open areas with sparse plant cover 

(TPWD 2009g). They dig for hibernation, nesting, and insulation purposes, and are commonly 

associated with loose sand or loamy soils. Populations have declined precipitously in eastern 

Texas and their decline may be related to the spread of fire ants, use of insecticide to control 

fire ants, heavy agricultural use of the land and other habitat alterations (NatureServe 2009b). 

Another factor implicated in their decline is over-collecting for pet and curio trade. This species 

is particularly vulnerable to the loss of harvester ants which make up nearly 70 percent of their 

diet. 

Timber/canebrake rattlesnake

The timber rattlesnake (Crotalus horridus) is a State-listed threatened species (TPWD 2009f). It 

prefers moist lowland forests and hilly woodlands or thickets near permanent water sources 

such as rivers, lakes, ponds, stream and swamps (TPWD 2009g). Their range extends from 

central New England to northern Florida, and west to eastern Texas, where their distribution is 

spotty (NatureServe 2009b). 
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American peregrine falcon 

The American peregrine falcon (Falco peregrines anatum) is a State-listed threatened species 

(TPWD 2009f). The bird is a year-round resident and local breeder in west Texas where it nests 

in tall cliff eyries (TPWD 2009g). The bird also migrates across Texas from breeding areas in 

the United States and Canada to winter along the coast and farther south. The American 

peregrine falcon occupies a wide range of habitats during migration, including urban areas. 

Populations are primarily concentrated along coast and barrier islands. The birds are lowaltitude migrants, with stopovers at leading landscape edges such as lake shores, coastlines, 

and barrier islands. 

Bachman’s sparrow

Bachman’s sparrow (Peucaea aestivalis) is a State-listed threatened species (TPWD 2009f). 

The sparrow is a permanent resident that occurs only in the far eastern portion of the state 

(Benson and Arnold 2001). It prefers areas with a high density of herbaceous cover and an 

open overstory. It historically was found in pineywoods with mature, open pine forests and 

savannah maintained by frequent fires. Today, with the dramatic decline in this forest type, the 

sparrow seems to tolerate treeless, grassy areas, abandoned fields or early stages of 

regenerating clearcuts. 

Bald eagle 

Although recently delisted as a Federally endangered species, the bald eagle (Haliaeetus 

leucocephalus) is listed as threatened in Texas and will remain Federally protected under the 

Bald and Golden Eagle Protection Act and the Migratory Bird Treaty Act (TPWD 2009f). The 

species will also continue to be protected under the ESA through management guidelines that 

will be in place for the next five years. Most eagles breed in Canada and the northern United 

States and move south for the winter (NatureServe 2009b). Bald eagles can be year-round 

residents in areas where water bodies do not freeze. Winter roost sites can vary with proximity 

to food resources, and eagles commonly roost communally in large trees, preferably snags. 

Interior least tern

The interior least tern (Sternula antillarum athalassos) is a Federally and State-listed 

endangered species (FWS 2009a; TPWD 2009f). The birds breed along major inland river 

systems but appear to be restricted to less altered and more natural river segments (TPWD 

2009g). Interior least terns nest on bare or sparsely vegetated sand, shell, and gravel beaches, 

islands, and salt flats associated with rivers and reservoirs. The birds prefer open habitat and 

avoid thick vegetation and narrow beaches. They arrive at breeding areas in early April to early 

June after wintering along the Central American coast and the northern coast of South America. 
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Piping plover

The piping plover (Charadrius melodus) is a State-listed threatened species (TPWD 2009f). 

This species is Federally-listed as threatened in the state of Texas, but is not listed as occurring 

in Freestone County by FWS (FWS 2009a). Texas is the wintering home for more than 5000 

known breeding pairs which have migrated from the Great Lakes regions and southern Canada 

(TPWD 2009g). They live on sandy beaches and lakeshores along the Gulf coast and could 

migrate through Freestone County. 

Whooping crane 

The whooping crane (Grus americana) is a Federally and State-listed endangered species 

(FWS 2009a; TPWD 2009f). They breed in Canada during the summer months and migrate in 

the fall to the Aransas National Wildlife Refuge along the Texas coastal plain, staying there from 

November through March (TPWD 2009g). Their winter and migrating habitat includes marshes, 

shallow lakes, lagoons, salt flats, grain and stubble fields (NatureServe 2009b). Migration 

habitat includes sites with good horizontal visibility, water depth of 30-cm or less, and a 

minimum wetland size of 0.04-ha for roosting. 

Wood stork 

The wood stork (Mycteria americana) is a State-listed threatened species (TPWD 2009f). 

Nesting appears to be restricted to Florida, Georgia, and South Carolina, however they may 

have formerly bred in Texas (FWS 2009b), but there are no breeding records since 1960 

(TPWD 2009g). Wood storks forage in prairie ponds, flooded pastures or fields, ditches, and 

other shallow standing water, including salt-water. The birds usually roost communally in tall 

snags, sometimes in association with other wading birds (i.e., active rookeries). A distinct, nonlisted population of wood storks breed in Mexico and birds then move into Gulf States in search 

of mud flats and other wetlands, even those associated with forested areas. 

Red wolf

The red wolf (Canis rufus) is a State-listed endangered species (TPWD 2009f). Red wolves 

inhabited brush and forested areas, as well as the coastal prairies (Davis and Schmidly 1994). 

They formerly ranged throughout eastern Texas, but appear to now be extinct. 

Building Impacts 

Building two nuclear power units and a reservoir at Trinity 2 would affect up to 2500 ac of land 

resulting in the permanent loss of 2000 ac of terrestrial habitat. Three-hundred ac would be 

required for permanent structures, and facilities, and up to 1700 ac would be for a new 

reservoir. Of the acreage that would be permanently affected, 350 ac would be forested 
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including 80 ac of high quality forested wetlands (Table 9-17) and 1600 ac of open grasslands. 

In addition, the land required for transmission corridors, water pipelines, road, or rail access is 

estimated to impact an additional 303 ac. The water storage reservoir would be created off of 

Tehuacana Creek (STPNOC 2010a), and would flood portions of Tehuacana Creek, Big Brown 

Creek, and other smaller tributaries in the area (STPNOC 2010a). The project could result in 

localized, direct, and adverse impacts to wetlands. 

To accommodate the building and operation of two nuclear units on the Trinity 2 site, STPNOC 

would need to clear undisturbed terrestrial habitats to connect existing power lines with new 

lines (STPNOC 2010a). The terrain along the likely transmission corridor is similar to that of the 

Trinity 2 site (STPNOC 2009a). The Trinity 2 site is 2.6 mi east of the Big Brown Power Plant 

and new lines would traverse a distance of 5 mi to connect to multiple 345kV lines. A new 

corridor would be needed to access these lines. Based on 5 mi and a 200-ft width corridor, 

installation of new lines would impact 120 ac in Freestone County. Although the most direct 

route would be used, efforts would be made to avoid natural or man-made areas where 

important environmental resources are located. No areas designated by the FWS as critical 

habitat for endangered species exist on the Trinity 2 site or adjacent to associated transmission 

lines (FWS 2009d). Erection of transmission towers and stringing of new lines would be 

expected to comply with all applicable laws, regulations, permit requirements, and use of best 

management practices. (STPNOC 2010a) 

In addition to transmission lines, there would be possible impacts associated with the building of 

pipelines to deliver cooling water to the reservoir/plant site. Transportation corridors (both road 

and rail) would also be needed at the Trinity 2 site. Acreage estimates for these activities are: 

120 ac for 19.5 mi of rail (50-ft width), 36 ac for 4 mi of pipeline for the cooling water intake/ 

discharge between the Trinity River and new reservoir (75-ft width), and 27 ac for a 3.0-mi 

access road (75-ft width) (STPNOC 2010a). 

There are no published records of Federal or state-listed species available for the Trinity 2 site 

(STPNOC 2010a). Federally and State-listed species for Freestone County were discussed 

above. No critical or sensitive habitats have been identified in the site area although portions of 

the Trinity River and Tehuacana Creek include Priority Bottomland Hardwood habitat which 

have high habitat resource value, particularly for waterfowl. The site area, particularly along 

Tehuacana Creek heading towards Richland-Chambers Reservoir contains excellent deer, wild 

turkey, and grey squirrel habitat. The Richland Creek WMA is within 7 mi of the site. The WMA 

was created to compensate for habitat loss associated with the construction of the RichlandChambers Reservoir; it was developed to provide habitat for indigenous and migratory wildlife 

species (TPWD 2009c). 

Building two new nuclear units at the Trinity 2 site would result in the permanent loss of 

approximately 2000 ac of terrestrial habitat including 350 ac of forested habitat and 80 ac of 

wetlands. However, the new reservoir would provide habitat for waterfowl. Clearing land for the 
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transmission line corridor would increase habitat fragmentation along the 5-mi corridor. Other 

sources of impacts to terrestrial resources such as noise, increased risk of collision and 

electrocution, and displacement of wildlife would likely be temporary and result in minimal 

impacts to the resource. Building the two new units would noticeably alter the available 

terrestrial habitat. 

Operational Impacts 

Impacts on terrestrial ecological resources from operation of two new nuclear units at the 

Trinity 2 site would include those associated with transmission system structures, and 

maintenance of transmission line corridors. Also, during plant operation, wildlife would be 

subjected to impacts from increased traffic. An evaluation of specific impacts resulting from 

presence of transmission lines and transmission line corridor maintenance cannot be conducted 

in any detail due to the lack of information, such as the locations of any new corridors that could 

result from transmission system upgrades. However, in general, impacts associated with 

transmission line operation consist of bird collisions with transmission lines, EMF effects on flora 

and fauna, and habitat loss due to corridor maintenance. 

Direct mortality resulting from birds colliding with tall structures has been observed (Erickson et 

al. 2005). Factors that appear to influence the rate of avian impacts with structures are diverse 

and related to bird behavior, structure attributes, and weather. Migratory flight during darkness 

by flocking birds has contributed to the largest mortality events. Tower height, location, 

configuration, and lighting also appear to play a role in avian mortality. Weather, such as low 

cloud ceilings, advancing fronts, and fog also contribute to this phenomenon. Waterfowl may be 

particularly vulnerable due to low, fast flight and flocking behavior (Brown 1993). Although 

additional transmission lines would be required for two new nuclear units at Trinity 2, increases 

in bird collisions directly attributable to these lines would be minor and these would likely not be 

expected to cause a measurable reduction in local bird populations. Consequently, the 

incremental direct mortality posed by the addition of new transmission lines for two new nuclear 

units would be negligible at Trinity 2. 

EMFs are unlike other agents that have an adverse impact (e.g., toxic chemicals and ionizing 

radiation) in that dramatic acute effects cannot be demonstrated and long-term effects, if they 

exist, are subtle (NIEHS 2002). A careful review of biological and physical studies of EMFs did 

not reveal consistent evidence linking harmful effects with field exposures (NIEHS 2002). The 

magnetic fields from many lines, at a distance of 300 ft are similar to typical background levels 

in most homes (NIEHS 2002). Thus, impacts of EMFs on terrestrial flora and fauna are of small 

significance at operating nuclear power plants, including transmission systems with variable 

numbers of power lines (NRC 1996). Since 1997, more than a dozen studies have been 

published that looked at cancer in animals that were exposed to EMFs for all or most of their 

lives (Moulder 2003). These studies have found no evidence that EMFs cause any specific 

types of cancer in rats or mice (Moulder 2003). 
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The impacts associated with corridor maintenance activities are loss of habitat due to cutting 

and herbicide application. The maintenance of transmission-line corridors could be beneficial 

for some species, including those that inhabit early successional habitat or use edge 

environments. Thus, corridor maintenance would not be expected to increase and contribute to 

cumulative effects. 

The potential effects of operating two new nuclear reactors at the Trinity 2 site would be 

primarily associated with maintenance of transmission corridors and increased traffic. 

Operational impacts to terrestrial resources would be expected to be minimal. 

Cumulative Impacts 

The impacts of building and operating two units at Trinity 2 were evaluated to determine the 

magnitude of their contribution to regional cumulative impacts on terrestrial ecological 

resources. The geographic area of interest for cumulative impacts is the intersection of the East 

Central Texas Plains ecoregion with the Lower Trinity-Tehucana watershed (Figure 9-14). 

There are a number of past, present, and potential future projects that could affect the terrestrial 

and wetland resources (Table 9-16). Past actions that have affected terrestrial resources 

include building the Big Brown Power Plant, approximately 3 mi west of the Trinity 2 site, and 

the Freestone Energy Center, approximately 7 mi northwest of the site. A third project is the Big 

Brown Mine, 4 mi northwest of the site. Luminant Mining, LLC, owner of the Big Brown Mine, 

has mined, leveled, and reclaimed 11,499 ac at the mine site (Gentry 1997). 

Projects or actions listed in Table 9-16 that could have future impacts on terrestrial resources 

include the Lakeside Energy Center, a 640-MW natural gas plant, planned for construction 

approximately 12 mi northwest of the Trinity 2 site. About 35 ac of terrestrial habitat would be 

needed for the site (Fairfield 2009). Luminant Mining, LLC is proposing to open the Turlington 

Mine next to the Big Brown Mine to mine an additional 10,000 ac at their facility 4 mi northwest 

of Trinity 2 site. There are several planned but currently unfunded highway widening projects 

within the geographic area of interest. In addition, two reservoirs are planned for the region: the 

Tehuacana Reservoir (approximately 15,000 ac) and the Tennessee Colony Lake 

(approximately 85,000 ac); both would inundate substantial areas of terrestrial habitat. 

The review team is also aware of the potential for GCC affecting the terrestrial resources in the 

geographic area of interest. The future impact of GCC on plant and wildlife species and their 

habitat in the geographic area of interest is not precisely known. GCC effects near the Trinity 2 

site could result in regional increases in the frequency of severe weather, decreases in annual 

precipitation, and increases in average temperature (GCRP 2009). The decrease in 

precipitation combined with increased temperatures and evaporation could result in more 

frequent droughts. Such changes in climate could alter and fragment terrestrial habitats 

(grasslands, forests, and wetlands) and result in shifts in species ranges, diversity, and 

abundance in the geographic area of interest for the Trinity 2 site (GCRP 2009). Because of the 
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February 2011 9-175 NUREG-1937 

regional nature of climate change, the impacts related to GCC would be similar for all the 

alternative sites, as they are all in the Great Plains Region. 

The potential cumulative impact to terrestrial resources within the area of interest given the two 

new reactors and cooling reservoir at the Trinity 2 site, the proposed Turlington Mine, the 

building of a new power plant, and the potential construction of two additional reservoirs would 

noticeably alter terrestrial resources. All these activities would remove or modify terrestrial 

habitats with the potential to affect important species living or migrating through the area. The 

incremental contribution of building and operating the two reactors at the Trinity 2 site to the 

cumulative impacts within the geographic area of interest would be significant. 

Summary 

Impacts to terrestrial ecology and wetland resources were estimated based on information 

provided by STPNOC and the review team’s own independent review. The review team 

concludes that there would be a loss of about 10 ac of high-quality forested wetlands associated 

with building two new nuclear units at the Trinity 2 site. Additional impacts to terrestrial 

resources would occur at the reservoir location based on the potential for affecting 350 ac of 

forested land, including high quality bottomland hardwood habitat, wetlands, and to a number of 

protected species that could potentially occur in the area. Although there is uncertainty 

concerning the possible routing of a new transmission line corridor, building impacts would 

probably be minimal given the small distance to existing transmission lines. There are several 

future activities in the region that would noticeably affect wildlife and wildlife habitat. These 

activities include the opening of the Turlington Mine, building the Lakeside Energy Center, and 

development of two large reservoirs (Tennessee Colony and Tehuacana). Based on the 

information provided by STPNOC and the review team’s independent evaluation, the review 

team concludes that the cumulative impacts within the area of interest on terrestrial plants and 

animals, including threatened or endangered species, and wildlife habitat in the region would be 

MODERATE. For the reasons discussed above in Building Impacts and Operational Impacts, 

the incremental contribution of building and operating two units at Trinity 2 and its associated 

reservoir to cumulative impacts within the geographic area of interest would be significant. 

9.3.4.4 Aquatic Resources 

The following impact analysis includes impacts from building activities and operations. The 

analysis also considers other past, present, and reasonably foreseeable future actions that 

impact aquatic resources, including other Federal and non-Federal projects listed in Table 9-16. 

For the analysis of aquatic ecological impacts at the Trinity 2 site, the geographic area of 

interest is considered to be the Trinity River drainage basin, from the upstream reaches of the 

Richland Chambers Reservoir to the proposed Tennessee Colony dam site (TWDB 2010a) 

because this is the area that the aquatic resources could be affected by new nuclear units. 
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Aquatic resources of the Trinity 2 site are associated with the Trinity River, Lake Fairfield, and 

local drainages (Tehuacana Creek, Big Brown Creek, and Rock Springs Branch). The Trinity 

River has been significantly influenced by urbanization and growth both upstream (Dallas-Fort 

Worth) and downstream (Houston). Water conditions in the Trinity River deteriorated to the 

point where numerous fish kills were common, even as recently as 1985 (USGS 2005). 

Through efforts to address wastewater discharge and manage water withdrawal, the Trinity 

River’s aquatic ecology has rebounded in recent years. Surveys of fish in the river have shown 

the improvement over time. From 1972-74, six surveys for fish were conducted and only four 

species of fish were identified (smallmouth buffalo [Ictiobus bubalus], gizzard shad [Dorosoma 

cepedianum], common carp [Cyprinus carpio], and yellow bass [Morone mississippiensis]), and 

no fish were collected in four of the six surveys. TPWD conducted additional surveys in 1987 

that indicated species richness was still low but the identification of 11 fish species was an 

indication of improvements to the aquatic resources. The most recent studies, performed by the 

USGS from 1993 to 1995, found a cumulative total of 25 fish species, including several game 

indigenous species. The presence of two darter species (bigscale logperch [Percina 

macrolepida] and slough darter [Etheostoma gracile]) suggests that the Trinity River is starting 

to recover and return to more natural conditions (USGS 2005). Today, the Trinity River in the 

vicinity of the Trinity 2 site is considered an ecologically significant stream segment based on its 

biological function, riparian conservation area, and the presence of protected aquatic species 

(TPWD 2010). 

Lake Fairfield supports the Big Brown Power Plant. The lake is an off-channel reservoir, and 

was formed by the damming of Big Brown Creek. Recreational fishing is popular in the lake and 

several fishing tournaments take place there every year. 

The area for a new reservoir to support the Trinity 2 site is located in the vicinity of Tehuacana 

Creek, Big Brown Creek, and Rock Springs Branch. No stream surveys for aquatic resources 

have been identified for Tehuacana Creek, Big Brown Creek, and Rock Springs Branch. Big 

Brown Creek begins three mi southwest of Fairfield in central Freestone County., and runs 

northeast 13 mi to the confluence with Tehuacana Creek, which is 4 mi east of Lake Fairfield. 

Tehuacana Creek flows from outside the town of Tehuacana for 42 mi to the confluence with the 

Trinity River. Tehuacana Creek and its major tributaries have been reported as having 

intermittent flow conditions; yet small potholes remain full of water during the drier periods of the 

year. 

Within the Trinity River drainage basin, from the upstream reaches of the Richland Chambers 

Reservoir to the proposed Tennessee Colony Dam site, there are a number of past, present, 

and potential projects that could affect the aquatic resources (Table 9-16). Past actions 

included building the lignite coal-powered Big Brown Power Plant, natural gas-powered 

Freestone Energy Center, Big Brown Lignite Coal Mine, and the Streetman Expanded Shale 

and Clay Plant. The Big Brown Lignite Coal Mine has plans to begin expanding its mining 
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activities (Turlington mine). The natural gas-powered Lakeside Energy Center is another 

proposed power-related project in the region. The Trinity River Authority has proposed 

additional reservoirs to be constructed off the Trinity River: Tennessee Colony and Tehuacana 

Reservoirs. In addition, the new nuclear units at the Trinity 2 alternative site would require 

building water intake and discharge systems with associated pipelines from the Trinity River to 

the new cooling water reservoir, inundation of existing water features at the Trinity 2 site, and 

establishing and operation of associated transmission corridors to connect with the existing 

power grid. Without having the specific plans for locating all facilities at the Trinity 2 site, the 

potential for impacts from building and operation of the new units to aquatic biota are assumed 

to be primarily to the organisms inhabiting the Trinity River, Tehuacana Creek, Big Brown 

Creek, and Rock Springs Branch. 

Non-Native and Nuisance Species 

No non-native or nuisance species have been recorded in the area as a problem. However, 

there are numerous nuisance aquatic species that TPWD considers to be ubiquitous across 

waterways in Texas. TPWD works to educate recreational boaters to remove nuisance aquatic 

plant species across the state and in the area of the Trinity 2 site. These species include: 

hydrilla, waterhyacinth, and giant salvinia. In addition, the Trinity River basin is known to have a 

number of non-native fish introduced to its waters including: common carp, grass carp, blacktail 

shiner, bullhead minnow, rudd, black buffalo, black bullhead, Western starhead topminnow, 

redspotted sunfish, tadpole madtom, plains killifish, yellow perch, red drum (Sciaenops 

ocellatus), tilapia (Oreochromis aureus) and walleye (Thomas et al. 2007; Hassan-Williams and 

Bonner 2009; TPWD 2009h). 

Important Species 

Recreational fishing is popular in the region of the Trinity 2 alternative site, particularly in Lake 

Fairfield. Access for recreational fishing in the Trinity River in the vicinity is limited because boat 

access is difficult. In Lake Fairfield, fishing for the following species is popular: alligator gar, 

largemouth bass, catfish (blue, channel, and flathead), and sunfish (longear [Lepomis 

megalotis], redear [L. microlophus], and hybrids) (TPWD 2007; STPNOC 2010a). Recreational 

and commercially important species for the Trinity River basin include the bluegill, blue catfish, 

channel catfish, flathead catfish, white crappie, black crappie, striped mullet, white mullet 

(M. curema), and warmouth (Thomas et al. 2007; TPWD 2007; Hassan-Williams and Bonner 

2009). The centrachids (largemouth bass, bluegill, crappies, sunfishes, and warmouth) typically 

inhabit lakes, rivers, and smaller flowing tributaries. The bass and warmouth are top carnivores, 

whereas the bluegill and crappies are insectivores. Alligator gar and catfish are top carnivores 

and are found primarily in larger waterbodies, like rivers and reservoirs. The striped and white 

mullet are more commonly found on the coast, and it is unclear if they travel and forage above 

Lake Livingston, which is below the Trinity 2 site (Thomas et al. 2007; Hassan-Williams and 

Bonner 2009). 
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There are no Federally listed aquatic species protected under the ESA in Freestone County. 

TPWD has identified numerous rare and protected aquatic species in Freestone County. These 

include several benthic macroinvertebrates that have been determined to be rare and located in 

the Trinity River basin: Morse's net-spinning caddisfly (Cheumatopsyche morsei), Holzenthal's 

philopotamid caddisfly (Chimarra holzenthali), purse casemaker caddisfly (Hydroptila ouachita), 

and another caddisfly (Phylocentropus harrisi). These invertebrates live on the bottom of 

streams (lotic systems) until they emerge from the water as a flying adult. One of the interesting 

characteristics of caddisflies is that the larvae produce and live inside cases, constructed of 

material gathered from the stream and held together by silk. Various families of caddisfly have 

unique cases. As larvae, they eat plants and periphyton. They are important in the food web 

for streams at all life stages as food for fish and birds. These organisms are not likely to thrive 

in slow or standing water, such as in a reservoir (Cushing and Allan 2001). 

TPWD has also identified a number of rare and protected freshwater mussels in the Trinity River 

basin: rock pocketbook (Arcidens confragosus), Wabash pigtoe (Fusconaia flava), creeper (or 

squawfoot) (Strophitus undulatus), pistolgrip (Tritogonia verrucosa), fawnsfoot (Truncilla 

donaciformis), and little spectaclecase (Villosa Iienosa). Not much is known about the 

distribution of these mussels in the area. However, these types of mussels, known as unioid 

mussels, are found in various water flows, from fast moving riffles in streams to quiescent 

ponds. Each species has adapted to a particular flow regime. These unioid mussels have a 

larval stage called a glochidium. For glochidia to mature to juvenile mussels, they must live as a 

parasite in the gill tissues of a host fish. An important component to the distribution of 

freshwater mussels in various water bodies is associated with the relationship between the 

mussels and the host fish (TPWD 2009d, 2009i). 

In addition, TPWD has recently listed as threatened four species of freshwater, unioid mussels 

that are found in Freestone County: Texas pigtoe (Fusconaia askewi), sandbank pocketbook 

(Lampsilis satura), Louisiana pigtoe (Pleurobema riddellii), and Texas heelsplitter (Potamilus 

amphichaenus) (Table 9-19) (TPWD 2009i; 35 Texas Register 249). These unioid mussels 

have similar life histories to those mentioned above. The Trinity River has one of the two 

largest populations of the Texas heelsplitter in the State, and has been noted as part of the 

designation for this reach of the river as an ecologically significant stream segment. The Texas 

pigtoe and the sandbank pocketbook mussels are being considered for protective status by the 

FWS (TPWD 2009i). 
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Table 9-19. Federally and State-Listed Aquatic Species that are Endangered, Threatened, 

and Species of Concern for Freestone County

Scientific Name Common Name State Status

Mussels 

Fusconaia askewi Texas pigtoe T 

Lampsilis satura sandbank pocketbook T 

Pleurobema riddellii Louisiana pigtoe T 

Potamilus amphichaenus Texas heelsplitter T 

Sources: TPWD 2009i; 35 Texas Register 249 

T = State-Listed Threatened 

Building Impacts 

Impacts of building a cooling water reservoir may be significant depending on the siting of the 

reservoir. The plans are for inundating portions of Tehuacana and Big Brown Creeks as well as 

other smaller tributaries in the area. Impacts from onsite building activities that have the 

potential to cause erosion and sedimentation in the local water bodies would be controlled or 

minimized by the implementation of an SWPPP (STPNOC 2010a). Inundation of small flowing 

streams would affect those aquatic resources that have specific habitat requirements. Fish 

species that have habitat requirements associated with lotic systems (flowing water) are often 

replaced with species more suited to lentic environments (standing water) (Linam et al. 1994). 

Habitat for these lotic species found in Tehuacana and Big Brown Creeks, associated wetlands, 

and drainages would be lost when these water bodies are inundated to create the reservoir, 

including any spawning areas for fish species that are dependent on flowing water. Most 

freshwater mussel species are adapted to a specific flow regime, and the inundation of this area 

could affect the distribution of the organisms in the region (STPNOC 2010a; TPWD 2009i). If 

habitat for the any of the State-listed mussels is found in the area to be inundated for the 

creation of the reservoir, TPWD might require mitigation activities (e.g., mussels could be 

collected and relocated). 

Water intake and discharge structures along the shoreline of the Trinity River would be required 

for the new reservoir at the Trinity 2 site (STPNOC 2010a). Building of a new intake and 

discharge in the Trinity River would likely require dredging and other significant alterations to the 

shoreline aquatic habitat. These activities would be permitted by the Corps and would be 

required to meet all State water quality requirements. Building of these structures on the Trinity 

River would result in the temporary displacement of aquatic biota within the vicinity of both 

structures. It is expected that the motile aquatic organisms would be displaced temporarily 

during building. However, the sessile aquatic biota (e.g., mussels) would be lost during building 

activities if the river substrate was removed or sedimentation covered the bottom of the river 

burying the organisms. Organisms like the mussel could possibly recolonize the disturbed river 

substrate with time. For the most part, the impacts on aquatic organisms would be temporary 
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and largely mitigable through the use of BMPs (e.g., silt screens). If required by TPWD, Statelisted mussels could be surveyed and removed before building activities as a mitigation action. 

Building transportation routes (heavy haul road and railroad spur), pipeline and transmission 

lines for the Trinity 2 site would result in the temporary displacement of some aquatic biota. 

Locations for these systems have not been identified. Expansion of existing corridors is 

expected to result in small environmental impacts while building new corridors could result in 

moderate impacts. Development of these corridors would employ BMPs to reduce impacts 

such that they would be temporary and localized (STPNOC 2010a). 

Building the cooling water reservoir for the two new nuclear reactors at the Trinity 2 site would 

inundate onsite water bodies. The habitat for the aquatic resources would change, and since 

most species cannot adapt to the reservoir environment, the species would be lost to the site. 

Thus, the building of the cooling water reservoir would be noticeable but not destabilizing to the 

aquatic resources. Building the intake and discharge structures on the Trinity River and in the 

new reservoir would affect the aquatic communities but the areas would be recolonized after 

building these structures was completed. Building of the transportation routes, transmission 

corridors, and pipelines would result in temporary and localized effects on aquatic communities. 

Operation Impacts 

To operate the two new units at Trinity 2, water rights for the Trinity River would have to be 

acquired. Currently, there are not sufficient water rights aggregated to a single point of 

diversion (50,000 ac-ft/yr). Instream flow studies necessary to maintain aquatic resources have 

not been evaluated for this reach of the river, and impacts associated with removal of water for 

the new reservoir are unknown. 

Impingement, entrainment, and entrapment of organisms from the Trinity River and from a 

constructed reservoir would likely be the most significant impacts to the aquatic population that 

could occur from operation of two new nuclear units at the Trinity 2 site. STPNOC states that 

using a closed-cycle cooling system with a cooling water reservoir would consume a maximum 

of 50,000 ac-ft of water per year (STPNOC 2010a). EPA’s design criteria for 316(b) Phase 1 

regulations (66 FR 65255) for intake structures would minimize impacts to aquatic biota in the 

Trinity River. The design criteria include: (1) closed-cycle cooling system that meets the EPA’s 

Phase I regulations for new facilities; (2) maximum through-screen velocity of 0.15 m/s (0.5 ft/s) 

at the cooling water intake; and (3) intake flow of less than or equal to 5 percent of the mean 

annual flow. Compliance with these regulations would minimize impingement, entrainment, and 

entrapment impacts to the aquatic biota. 

Operational impacts to aquatic resources associated with water quality, physical and thermal 

characteristics of the discharge cannot be determined without additional detailed analysis. A 

cooling water reservoir for the Trinity 2 site would likely evolve in a similar fashion to the MCR at 
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STP, where, with time, the reservoir has developed similar aquatic resources to that in the lower 

Colorado River and acclimated to the discharges of the operating reactor units. Effects on the 

aquatic resources in the Trinity River would depend on the type of cooling system as well as 

volume, frequency, and water characteristics of the discharge. These types of impacts can be 

addressed and minimized through operational procedures and the permitting process with 

TCEQ. 

Operational impacts to aquatic biota from onsite activities and in the transmission corridors 

would also be minimal assuming BMPs are used for maintenance of these areas and corridors. 

SWPPPs would ensure that impacts to biota from erosion and sedimentation would be minimal 

through the use of silt screens and controls for managing stormwater. These controls would be 

important for habitat quality and survival of benthic biota in the downstream drainages. 

Based on operation of the CWS, impacts to aquatic communities in the Trinity River and 

reservoir could result from impingement, entrainment, and entrapment as well as thermal, 

chemical, and physical characteristics of the discharge. STPNOC commits to compliance with 

State and Federal regulations for operation of intake and discharge structures that would be 

protective of aquatic resources. Once a community is established in the new reservoir, longterm effects from operation of the CWSs are not expected to noticeably alter aquatic 

communities in the Trinity River and reservoir. 

Cumulative Impacts 

In the Trinity River drainage basin, from the upstream reaches of the Richland Chambers 

Reservoir to the proposed Tennessee Colony Dam site, the aquatic resources have been 

heavily influenced over the years by urbanization, municipal water use, wastewater treatment, 

industrial use, and impoundments. Water use and discharge of wastewater from Dallas-Fort 

Worth area and other municipalities led to significant decline of the water quality as well as fish 

kills as recently as 1985 (USGS 2005; STPNOC 2010a). Construction of the off-channel 

Richland Chambers Reservoir and Lake Fairfield (for the Big Brown Power Plant) affected the 

local aquatic resources during inundation of the areas, and now the aquatic ecology of the local 

water ways and the reservoir have adapted to the changes in the water flows. Efforts by TCEQ 

and the municipalities have restored much of the aquatic life to the Trinity River (USGS 2005). 

Without careful water management of the Trinity River, aquatic resources could be degraded 

again. Future proposed projects, (e.g., the proposed Turlington Mine next to the existing Big 

Brown Lignite Coal Mine and the proposed Lakeside Energy Center) would increase water use 

in the area of interest and affect the aquatic resources in a similar manner to ongoing mining 

and power production facilities. The Texas Water Development Board and the Trinity River 

Authority have plans for the construction of additional reservoirs in the Trinity River near the 

Trinity 2 site. The proposed Tennessee Colony Reservoir would dam the Trinity River 

downstream of the Trinity 2 site and connect to the existing Richland Chambers Reservoir, the 

proposed Tehuacana Reservoir, and the existing Lake Fairfield (NRC 2009). Further 
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evaluations would be needed to determine if the operation of the dam for the Tennessee Colony 

Reservoir might affect the sharpnose shiner distribution. Building of these reservoirs would 

have a cumulative loss of stream and drainage habitat that would be substantially greater than 

the loss of habitat from the building of the cooling reservoir at the Trinity 2 site. 

Continued urbanization and agricultural practices could affect aquatic communities in the 

Trinity 2 geographic area of interest in the foreseeable future. Expansion of urban areas in the 

Trinity River drainage could increase water use, decrease available water for aquatic resources, 

and increase nonpoint pollution. The effects of continued agricultural practices could result in 

additional habitat loss and/or degradation due to irrigation using surface waters and 

groundwater withdrawal, point and non-point source pollution, siltation, and bank erosion. 

As mentioned above in the terrestrial section, GCC could result in regional increases in the 

frequency of severe weather, decreases in annual precipitation, and increases in average 

temperature (GCRP 2009). The decrease in precipitation combined with elevated water 

temperatures and evaporation could result in more frequent droughts, which could reduce 

aquatic habitat. Loss of habitat could cause shifts in species ranges, diversity, and abundance 

in the geographic area of interest for the Trinity 2 site (GCRP 2009). Specific predictions on 

aquatic habitat changes in this region resulting from GCC are inconclusive at this time. 

However, because of the regional nature of climate change, the impacts related to GCC would 

be similar for all the alternative sites. 

Based on building and operation of two new nuclear units at the Trinity 2 alternative site and 

other projects and influences in the region of influence for aquatic resources, the cumulative 

impacts would be noticeable and possibly destabilizing. All these activities would alter the 

aquatic habitats and potentially change the species composition and diversity in the affected 

water bodies. The incremental contribution of building and operating the two new reactors, 

including building of a cooling water reservoir, at the Trinity 2 site to the cumulative impacts 

within the geographic area of interest would be significant. 

Summary 

STPNOC has indicated that building of the cooling water reservoir at the Trinity 2 site would 

inundate existing water bodies and destroy habitat for aquatic resources that are dependent on 

flowing water. The review team concludes that the impacts from building two new nuclear units, 

including the new cooling water reservoir, at the Trinity 2 site would be noticeable but not 

destabilizing to the aquatic resources. The review team also concludes that the impacts from 

operation of two new units would be minimal. In the Trinity River drainage basin, from the 

upstream reaches of the Richland Chambers Reservoir to the proposed Tennessee Colony 

Dam site, the aquatic resources have been heavily influenced over the years by urbanization, 

municipal water use, wastewater treatment, industrial use, and impoundments. Based on the 

information provided by STPNOC and the review team’s independent evaluation, the review 
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February 2011 9-183 NUREG-1937 

team concludes that the cumulative impacts of building and operating two new reactors on the 

Trinity 2 site combined with other past, present, and future activities on most aquatic resources 

in the Trinity River drainage would be MODERATE to LARGE. For the reasons discussed in 

Building Impacts and Operational Impacts, the incremental contribution of building and 

operating the two new reactors at the Red 2 site to the cumulative impacts within the geographic 

area of interest would be significant. 

9.3.4.5 Socioeconomics 

The following impact analysis includes impacts from building activities and operations. The 

analysis also considers other past, present, and reasonably foreseeable future actions that 

impact socioeconomics, including other Federal and non-Federal projects listed in Table 9-16. 

For the analysis of socioeconomic impacts at the Trinity 2 site, the geographic area of interest is 

considered to be the 50-mi region centered on the Trinity 2 site with special consideration of 

Freestone and Anderson Counties as that is where the review team expects socioeconomic 

impacts to be the greatest. In evaluating the socioeconomic impacts of site development and 

operation at the Trinity 2 site near Fairfield, in Freestone County, the NRC review team 

undertook a reconnaissance survey of the site using readily obtainable data from the Internet or 

published sources. Impacts from both site development and station operation are discussed. 

Physical Impacts 

Many of the physical impacts of building and operation would be similar regardless of the site. 

Building activities can cause temporary and localized physical impacts such as noise, odor, 

vehicle exhaust, vibration, shock from blasting (if used), and dust emissions. The use of public 

roadways, railways, and waterways would be necessary to transport construction materials and 

equipment. Offsite areas that would support building activities (for example, borrow pits, 

quarries, and disposal sites) would be expected to be already permitted and operational. 

Potential impacts from station operation include noise, odors, exhausts, thermal emissions, and 

visual intrusions (the latter of which are treated under aesthetics and recreation below). New 

units would produce noise from the operation of pumps, cooling towers, transformers, turbines, 

generators, and switchyard equipment. Traffic at the site also would be a source of noise in 

Freestone County. Highway maps show that practical access to the site from the south, west, 

and northwest is I-45, then through the town of Fairfield (2008 population of 3618) (USCB 

2009a). While practical access from the east and northeast may avoid Fairfield, the patterns of 

access routes likely mean that during the building period several thousand additional cars per 

day may pass through Fairfield and its eastern outskirts at construction work shift changes, and 

would have very noticeable impacts on traffic and traffic noise. Any noise coming from the STP 

site would be controlled in accordance with standard noise protection and abatement 

procedures. This practice also would be expected to apply to all alternative sites, including the 

Trinity 2 site. Commuter traffic would be controlled by speed limits. Good road conditions and 
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appropriate speed limits would reduce the noise level generated by the workforce commuting to 

the alternative site, but there still would likely be very noticeable traffic noise increases in and 

near Fairfield. 

The new units at the Trinity 2 site would likely have standby diesel generators and auxiliary 

power systems. Permits obtained for these generators would ensure that air emissions comply 

with applicable regulations. In addition, the generators would be operated on a limited, shortterm basis. During normal plant operation, new units would not use a significant quantity of 

chemicals that could generate odors that exceed odor threshold values. Good access roads 

and appropriate speed limits would minimize the dust generated by the commuting workforce. 

Based on the information provided by STPNOC and the review team’s independent evaluation, 

the review team concludes that the physical impacts of building and operating two nuclear units 

at the Trinity 2 site would be minimal, except in Freestone County (Fairfield and vicinity), where 

increases in traffic noise would be very noticeable during the building period. 

Demography 

The Trinity 2 site is located in Freestone County 10.4 mi northeast of the city of Fairfield (2008 

population 3618) and approximately 20 mi west of Palestine (2008 population 18,344) in 

Anderson County (2008 population 56,838) (USCB 2009a,Texas Association of Counties 

2009e). After World War II Freestone County’s population declined up until the 1970s when it 

slowly began to rise again to its 2008 population of 18,923 (TSHA 2009f, Texas Association of 

Counties 2009f). 

STPNOC estimated the peak number of construction workers would be 5950. Approximately 

900 operations workers would also be onsite during the final phase (i.e., final 10 months) of 

building activities (STPNOC 2010a). Based on assumptions in Section 4.4 concerning inmigration for Units 3 and 4 in Matagorda County, and for comparability with the analysis in that 

section, the review team assumed that 50 percent or 2975 construction workers would inmigrate. Because no information is available on where the workforce would live, the review 

team assumed that half of the plant workforce would move to Freestone County and the other 

half to Anderson County. Eighty percent of in-migrating construction workers would bring a 

family. Other counties such as Navarro County would likely see an in-migration of workers as 

well, but considering the larger population of this county and the relatively small number of inmigrants they would be easily absorbed. All operations workers would in-migrate and all would 

bring a family. A family size of 3.25 was used for construction workers for a total peak site 

development related population increase of 8330 (7735 in-migrating workers and family 

members and 595 workers without family). The review team also assumed an average family 

size of 2.74 for the operating workforce (see Section 5.4), resulting in a total in-migrating 
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February 2011 9-185 NUREG-1937 

operations-related population of 2466 (900 operations workers plus families) at the peak of 

building activities. Therefore, the total expected in-migrating population at peak building would 

be 10,796. 

Considering that the maximum estimation of in-migrating population would be almost 30 percent 

of Freestone County’s total population and 9 percent of the total population in Anderson County, 

the demographic impacts of building activities are expected to be significant in both counties 

and potentially destabilizing for Freestone County. If the facility is constructed and commences 

operations, the operational workforce would number about 959 workers, 900 of whom would be 

at the site during peak site development and are included in the above analysis. The review 

team expects that the demographic impact during operation would be minimal. Based on the 

information provided by STPNOC and the review team’s independent evaluation, the review 

team concludes that the demographic impacts of building would be significant and potentially 

destabilizing. The demographic impacts of operating two nuclear units at the Trinity 2 site would 

be minimal. 

Taxes and Economy 

As discussed in Sections 4.4 and 5.4, in-migrating workers who buy property within the region 

would pay property taxes to the respective county, workers would also pay both the state and 

county sales and use tax on all eligible purchases as would STPNOC on all eligible purchases 

related to the two units. As described in Section 5.4.3.2, STPNOC estimates it would spend 

$60 million on annual expenditures for goods and services related to the new units of which 

about 20 percent ($12 million) would be spent locally (STPNOC 2010a). STPNOC estimated if 

the units were 100 percent taxable, annual franchise taxes for Unit 3 would be $4.7 to 

$5.4 million and Unit 4 would have payments of $3.9 to $4.7 million, which would represent less 

than 1 percent of the State’s annual franchise tax revenues. 

The largest tax impacts would come from property taxes related to the development and 

operation of the two units. The private owners of any new units built at the Trinity 2 site would 

pay taxes to the county, any applicable special districts that exist within the county and the local 

school district in which the land sits in. During the building process, county property tax 

payments would be based on the cost of building the units and determined in accordance with 

state law using mutually agreed on appraisal formulas (STPNOC 2010a). During operations 

property taxes would range from $6.10 million to $13.86 million. Taxes from the nuclear plant 

would represent a 56 to 127 percent increase over the 2008 Freestone County taxes levied of 

$10.9 million. 

An increased appraised value in the district would increase the tax payments made to Fairfield 

ISD. However, Fairfield ISD is a Chapter 41 “wealthy district,” and by State law would have to 

pass most, if not all, plant-related property taxes to the State of Texas for redistribution 

(TEA 2009). 
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Under new legislation, Fairfield ISD and Fairfield County would be allowed to enter into an 

agreement with the plant owner which would reduce owner’s taxes and allow the ISD and 

County to share in the tax savings. The money the district may receive would not be subject to 

the state’s equalization laws and would not have to be sent back to the State. If such an 

agreement were reached, the tax payments are likely to represent a significant beneficial impact 

for both a small, rural county such as Freestone County and for Fairfield ISD. 

Economic impacts would be spread across the 50-mi region, but would be greatest in Freestone 

and Anderson Counties. Per capita income for Freestone County in 2007 is $26,107 and 

$23,399 for Anderson County. The 2008 unemployment rate for Freestone County and 

Anderson County was 4.1 percent and 5.7 percent, respectively (Texas Association of Counties 

2009f, e). The wages and salaries of the site development and operating workforce would 

stimulate the local economies and could provide noticeable and significant impacts for new 

businesses to get started and for increased job opportunities for local residents. Based on the 

information provided by STPNOC and the review team’s independent evaluation, the review 

team concludes that the tax and economic impacts of building and operating two nuclear units 

at the Trinity 2 site would be significant and beneficial. 

Transportation and Housing 

The transportation network in the area includes Interstate 45 (I-45), US-84, SH-75 and several 

FM roads. Primary commuter access from the south would be from US-84, I-45, and the west 

on SH 75 and FM27. Commuters from Palestine and Corsicana could also use US 287 and 

FM 488. As discussed under physical impacts, the most practical commuting routes to the 

Trinity 2 site from the north, west, and south converge on the city of Fairfield, resulting in a 

traffic increase of several thousand cars per day. It is likely that the city of Fairfield would 

experience a very noticeable increase in traffic as a result. In addition, Freestone County 

population is projected to grow enough to significantly impact traffic, with lower but noticeable 

impacts in Anderson County. There are numerous secondary roads near the site, several that 

lead to the Big Brown Plant. The only roads that lead to the nearby Trinity 2 site are one lane 

unimproved roads. A new access road would need to be built which would likely be from the 

west off FM 2570 (STPNOC 2010a). Other major road upgrades would be needed to support 

site development. The building of a nuclear plant on the Trinity 2 site would have significant 

adverse impacts in Freestone County and noticeable adverse impacts elsewhere on the local 

transportation network. 

Approximately 3875 construction and operations workers could migrate into the region during 

peak building activities. During operations the workforce is expected to be about 959 workers of 

which 900 are included in the 3875 workers needing housing during peak building activities. 

The most recent data for Freestone County estimated a total housing stock of 8138 units (USCB 

2009g) and 19, 243 for Anderson County, with a rental vacancy rate of 5.6 percent. 

Approximately 3690 housing units were unoccupied at the time of the survey (USCB 2009h). 
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February 2011 9-187 NUREG-1937 

Some workers may choose to find other housing such as an apartment while others may inmigrate with their own housing in the form of a travel trailer. Given Freestone County’s rural 

nature and small number of overall housing units, the review team expects that the in-migrating 

workforce of 3875 would cause a noticeable and potentially destabilizing impact on the housing 

market within the two county socioeconomic impact area and mitigation may be warranted. 

Based on the information provided by STPNOC and the review team’s independent evaluation, 

the review team concludes that the transportation and housing impacts of building and operating 

two nuclear units at the Trinity 2 site would be noticeable and potentially significant. 

Public Services and Education 

The influx of construction workers and plant operations staff settling in the region could impact 

local municipal water and water treatment facilities and other public services in the region. 

These impacts would likely be in proportion with the demographic impacts experienced in the 

region, unless these resources have excess capacity or are particularly strained during building, 

which would decrease or increase the impact, respectively. For example, the largest water 

treatment facilities in Freestone County and Anderson County have water capacity available 

that is roughly three to four-and-a-half times current average daily consumption (EPA 2009b, 

TCEQ 2010a), so while they may have to build considerable distribution infrastructure they are 

unlikely to be water capacity limited. 

The in-migrating construction workers would likely put a temporary strain on public services 

during peak site development due to the significant population increases in each county. 

Therefore, the review team expects site building-related impacts on public services would be 

noticeable and potentially destabilizing, at least in Freestone County. During operations the 

impact on public services would be minimal. 

Freestone County has 4 independent school districts with 15 schools and Anderson County has 

7 independent school districts with 23 schools. The 2007-2008 student enrollments for 

Freestone and Anderson County are 3667 students and 8539 students, respectively (NCES 

2009). The review team expects a peak site development-related increase of about 2537 

students (1269 in each county). The in-migrating students would represent a significant 

increase in students in both counties (35 percent in Freestone County and 15 percent in 

Anderson County) therefore; the review team expects impacts to educational services would be 

significant and potentially destabilizing during peak building activities in at least Freestone 

County and possibly in Anderson County. During operations, this impact would reduce to 

minimal levels. Based on the information provided by STPNOC and the review team’s 

independent evaluation, the review team concludes that the public service and education 

impacts of building and operating two nuclear units at the Trinity 2 site would be significant. 
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NUREG-1937 9-188 February 2011 

Aesthetics and Recreation 

Recreation in the area includes the Catfish Creek, Gus Engeling WMA, Big Lake Bottom WMA, 

Richland Creek WMA, Richland Chambers Reservoir and Fairfield Lake State Park. Fairfield 

Lake State Park is located 2.5 mi southwest of the site and has the most recreational 

opportunities. During the winter months fishing tournaments are held every weekend. Other 

activities include picnicking, boat ramps, playgrounds, an amphitheater, hiking, biking, 

equestrian and bird watching (STPNOC 2010a). The development of transmission lines to 

support the site would likely follow the Big Brown corridor, and the aesthetics of the site vicinity 

are already degraded by the existence of the Big Brown plant. The review team concludes that 

the visual impact associated with building and operating two nuclear units on this site would 

have a minimal impact on the aesthetics resources in the area. Increased building-related traffic 

to and from the plant could significantly impact recreation at Fairfield Lake State Park during the 

building period and would be noticeable in Freestone County; however, the overall impact to 

recreation elsewhere would be minimal. Based on the information provided by STPNOC and 

the review team’s independent evaluation, the review team concludes that the aesthetic and 

recreation impacts of building and operating two nuclear units at the Trinity 2 site would be 

minimal. 

Summary of Socioeconomics 

Physical impacts on workers and the general public include impacts on existing buildings, 

transportation, aesthetics, noise levels, and air quality. Social and economic impacts span 

issues of demographics, economy, taxes, infrastructure, and community services. In summary, 

on the basis of information provided by STPNOC and the review team’s independent 

evaluation, the review team concludes that the socioeconomic impacts of the building of a new 

nuclear plant at the Trinity 2 site would be significant and adverse for Anderson County and 

potentially destabilizing in Freestone County in terms of demographics, transportation, housing, 

public services, and education. Housing impacts during building would be significant and 

adverse in Anderson County and probably destabilizing and adverse in Freestone County. 

These impacts would be minimal and adverse during operations. Physical impacts (with the 

exception of traffic-related noise in Freestone County) and impacts on aesthetics would be 

minimal in both counties, but recreation could be noticeably affected during the building period 

in Freestone County due to access issues at Fairfield State Park. The impacts on the 

economy and tax base during building and operations likely would be beneficial and significant 

for Freestone County and beneficial and noticeable in Anderson County. The review team 

expects all physical and socioeconomic impacts on other areas within the region would be 

minimal, except in Freestone County where the impacts to recreation could be noticeable 

during building. 
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February 2011 9-189 NUREG-1937 

Cumulative Impacts 

In addition to assessing the incremental socioeconomic impacts from the building and 

operations of two additional nuclear units on the Trinity 2 site, the cumulative impact is also 

considered. The cumulative analysis considers other past, present, and reasonably foreseeable 

future actions that could contribute to the cumulative socioeconomic impacts on a given region, 

including other Federal and non-Federal projects and those projects listed in Table 9-16. For 

the analysis of socioeconomic impacts at the Trinity 2 site, the geographic area of interest is 

considered to be the 50-mi region centered on the Trinity 2 site. 

Economic impacts would be spread across the 50-mi region but would be greatest in Freestone 

and Anderson Counties. After World War II Freestone County’s population declined up until the 

1970’s when it slowly begin to rise again to its current 2008 population of 18,923 (Texas 

Association of Counties 2009f). Farming began declining before World War II and continued for 

several decades afterwards. During the 1970s and 1980s farming increased as new 

businesses also moved into the area. Mining became very important to the area by the late 

1980’s. Anderson County’s economy has been based on manufacturing. Oil and gas 

discoveries, iron ore deposits, timber regions, and good ranchlands kept the price of farmland 

high. Another contributor to the local economy has been the three prison units located near 

Fairfield (TSHA 2009g, h). 

Most of the projects identified in Table 9-16 have or would contribute to the impacts on 

demographics, economic climate, and community infrastructure of the region and generally 

result in increased urbanization and industrialization. However, many impacts such as those on 

housing or public services are able to adjust over time, particularly with increased tax revenues. 

Furthermore, state and county plans along with modeled demographic projections include 

forecasts of future development and population increases. But several of the proposed energy 

and mining facilities (for example, the existing Big Brown Mine and the proposed Turlington 

Mine, which is expected to be operational in 2011) are close to the Trinity 2 site and have 

substantial workforces. Depending on the timing of these proposed activities, the coincidence 

of several projects is a potential socioeconomic concern for Freestone County, which could 

have to deal with significant impacts from building at the Trinity 2 site while also dealing with 

workers from these other projects. Although the projects identified in Table 9-16 would be 

consistent with applicable land-use plans and control policies, the review team considers that 

managing the cumulative socioeconomic impacts from the projects would be possible but could 

be challenging. Tehuacana Reservoir and Tennessee Colony Reservoir projects represent two 

reasonably foreseeable activities within close proximity to the Trinity 2 site. While each of those 

projects could impose additional socioeconomic impacts, the planned starting and completion 

dates and the level of activity for these projects are all uncertain. Therefore, the review team 

concluded that for the purposes of this alternative site analysis the socioeconomic impacts of 

those two projects could not be quantitatively evaluated. However, although the timing of the 

impacts is not known, the review team expects that the following effects may occur should either 
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NUREG-1937 9-190 February 2011 

reservoir be developed. The review team would expect temporary increases in economic 

activity, population, and traffic during the construction period; and decreases in the existing 

property tax base, which may or may not be offset by values of recreational development, and 

other improvements related to reservoirs. In addition, during reservoir operations, depending on 

the level of development (and population), there may be increases in the demand for 

infrastructure and community services. There is a possibility that recreational opportunities 

would increase. 

In summary, on the basis of information provided by STPNOC and the review team’s 

independent evaluation, the review team concludes that the cumulative socioeconomic impacts 

during the building of a new nuclear plant at the Trinity 2 site would be MODERATE and 

adverse for Anderson County and LARGE and adverse for Freestone County in terms of 

demographics, transportation, housing, public services, and education. These impacts would 

be SMALL and adverse during operations. Cumulative impacts on aesthetics and recreation 

and physical impacts in Freestone County would be MODERATE and adverse during the 

building period and SMALL and adverse elsewhere. These impacts would all be SMALL and 

adverse during operations. The cumulative impacts on economy and tax base during building 

and operations likely would be beneficial and LARGE in Freestone County and beneficial and 

SMALL to MODERATE in Anderson County. The review team expects all cumulative physical 

and socioeconomic impacts on other areas within the region would be SMALL. Building and 

operating a new plant at the Trinity 2 site would make a significant, incremental contribution to 

these impact levels. 

9.3.4.6 Environmental Justice 

The following impact analysis includes impacts from building activities and operations. The 

analysis also considers other past, present, and reasonably foreseeable future actions that 

impact environmental justice, including other Federal and non-Federal projects listed in 

Table 9-16. The cumulative environmental justice impacts were assessed for the 50-mi region 

centered on the Trinity 2 site, with allowance made for counties downstream in case offsite 

surface water-related impacts were identified for any human population. In 2000, the 50 mi 

region around the Trinity 2 site was characterized as 14.2 percent Black, 0.5 percent American 

Indian and Alaskan Native, 0.4 percent Asian, 0.07 percent Hawaiian and Other Pacific Islander, 

5.6 percent all other races, and 1.3 percent two or more races, 10.2 percent Hispanic or Latino 

and 12.3 percent low-income (STPNOC 2010a). 

The 2000 Census block groups were used for ascertaining minority and low-income populations 

in the region (USCB 2000a, c). There were a total of 282 census blocks groups within the 50-mi 

region, 41 of which were classified as minority populations (2 of them in Freestone County and 

8 of them in Anderson County). One of these populations in Anderson County is within 10 mi of 

the Trinity 2 alternative site. There are 14 census block groups classified as low income in the 

50-mi region, none of which are in Freestone County and 2 in Anderson County. None of these 
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February 2011 9-191 NUREG-1937 

populations is within 10 mi of the Trinity 2 alternative site, but there are minority populations on 

both sides of the Trinity River downstream from the Trinity 2 site. The review team does not 

know if they are dependent on the river for water supply or if they are engaged in subsistence 

activity. See Figure 9-15 and Figure 9-16 for the location of minority or low-income populations 

within the 50-mi region. 

The review team’s analysis did not find any information suggesting that minority or low income 

populations in the area were dependent on natural resources that would be adversely affected 

by a nuclear power plant at the Trinity 2 alternative site. 

Physical impacts during building (noise, fugitive dust, air emissions, traffic) would not impose 

disproportionately high and adverse impacts on minority populations because of their distance 

from the Trinity 2 site. However, the operation of the proposed project at the Trinity 2 site may 

have a disproportionately high and adverse impact on minority or low-income populations due to 

impacts on surface water supplies. Surface water-related impacts during operations were 

described in Section 9.3.4.2 as at least noticeable and adverse because of ambiguity 

concerning available water rights on the Trinity River and concerns about the water available to 

downstream users. See Sections 4.5 and 5.5 for more information about environmental justice 

criteria and impacts. 

With the possible exception of the Big Brown Power Plant, 2.6 mi west of the Trinity 2 site, the 

existing projects identified in Table 9-16 are not likely to have disproportionately high and 

adverse impacts on minority and low-income populations of the region. Neither Big Brown nor 

its associated mining operations are close to minority or low income populations, but they are 

significant employers. If additional major construction projects such as the proposed 

Tehuacana Reservoir and Tennessee Colony reservoir projects commence at the same time as 

building new nuclear units at the Trinity 2 site, that could cause a greater general rise in rental 

rates than that due to one project alone, but it is not clear whether any general rent increase 

would have a disproportionately high and adverse impact on rental prices experienced by lowincome populations or whether these populations would be uniquely impacted due to their lower 

household budgets. 

Based on information provided on water use by STPNOC and the review team’s independent 

reconnaissance evaluation, MODERATE impacts to surface water resources and aquatic 

resources are expected in the region of the Trinity 2 site downstream from the site. However, 

the review team did not find any information suggesting that the minority populations located 

downstream near the Trinity 2 site had any disproportionate dependence on the Trinity River for 

water supply and subsistence activities. Accordingly, the review team concludes that the 

environmental justice impacts from locating the proposed project at the Trinity 2 site would be 

SMALL and adverse. 
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Figure 9-15. Block Groups With Minority Populations Meeting Environmental Justice Selection 

Criteria Within 50 mi of the Trinity 2 Alternative Site (USCB 2000a)
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February 2011 9-193 NUREG-1937 

Figure 9-16. Block Groups With Low-Income Popualtions Meeting Environmental Justice 

Selection Criteria Within 50 mi of the Trinity 2 Alternative Site (USCB 2000c)
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NUREG-1937 9-194 February 2011 

9.3.4.7 Historic and Cultural Resources 

The following impact analysis includes impacts from building activities and operations 

associated with two new nuclear generating units at the Trinity 2 site. The analysis also 

considers other past, present, and reasonably foreseeable future actions that may impact 

historic and cultural resources, including other Federal and non-Federal projects listed in 

Table 9-16. For the analysis of cultural impacts at the Trinity 2 site, the geographic area of 

interest is considered to be the APEs that would be defined for this site. This includes the 

physical APE, defined as the area directly affected by the site development and operation 

activities at the site and transmission lines, and the visual APE. The visual APE is defined as 

an additional 1-mi radius around the physical APE consistent with the discussion in Section 2.7 

about the maximum distance from which the structures can be seen. 

Reconnaissance activities in a cultural resource review have particular meaning. Typically, for 

example, it includes preliminary field investigations to confirm the presence or absence of 

cultural resources. However, in developing this EIS, the review team relied upon 

reconnaissance-level information to perform its alternative site evaluation, in accordance with 

ESRP 9.3 (NRC 2000). Reconnaissance-level information is data that are readily available from 

agencies and other public sources. It can also include information obtained through visits to the 

site area. To identify the historic and cultural resources at the Trinity 2 site, the following 

information was used: 

• STPNOC ER (STPNOC 2010a) – including the THC’s Texas Archeological Sites Atlas; 

• NRC Alternative Sites Visit August 2009; and 

• A Survey of the Environmental and Cultural Resources of the Trinity River (Fisher et al. 

1972) – a report of studies completed in 1971 for proposed Corps projects along the Trinity 

River, including Chapter I on the “Archaeological and Historical Aspects of the Trinity River 

Development,” by Archie P. McDonald 

The Trinity 2 site is located in Freestone County, Texas, and is a greenfield site. Historically, 

the site and vicinity were largely undisturbed and likely contained intact archaeological sites 

associated with the past 10,000 years of human settlement. Over time, the area has been 

disturbed by rural development and cleared for agricultural purposes. According to an overview 

of archaeological research in the Trinity River Basin (Fisher et al. 1972), little work has been 

done to identify cultural or historic resources along the middle reaches of the Trinity River, 

where the Trinity 2 site is located and no significant Paleo-Indian or Archaic sites have been 

discovered in the surveys that have been completed in adjacent areas. Based on this 

reconnaissance-level evidence, it appears that the APEs associated with a proposed plant at 

the Trinity 2 site do not have any historic properties likely to be affected by building or operating 

new units (STPNOC 2010a). However, no onsite archaeological and/or architectural surveys 

have been conducted at the Trinity 2 site. 
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One historic structure, a railroad depot and office building, listed on the National Register of 

Historic Places is found in Freestone County. It is located approximately 10 mi away from the 

site. Eleven archaeological sites have been recorded within a 2-mi radius of the Trinity 2 site, 

the closest of which is within 0.5 mi, and several cemeteries are located nearby (STPNOC 

2010a). None of the cemeteries are listed on the National Register. The project has the 

potential to affect resources through visual impacts from buildings and transmission lines. 

Should such properties be subsequently listed on the National Register or additional properties 

be identified, then these impacts may result in significant alterations to the visual landscape 

within the geographic area of interest. 

To accommodate building two new nuclear generating units on the Trinity 2 site, STPNOC 

would need to clear approximately 800 ac for the main power plant site, approximately 183 ac 

for offsite transportation and pipeline corridors, and up to 1700 ac for a new reservoir (STPNOC 

2010a). In the event that the Trinity 2 site was chosen for the proposed project, identification of 

cultural resources would be accomplished through cultural resource surveys and consultation 

with the Texas SHPO at the THC, Tribes and interested parties. The results would be used in 

the site planning process to avoid cultural resources impacts. In the event significant cultural 

resources were identified by these surveys, the review team assumes that STPNOC would 

develop protective measures in a manner similar to those for the STP site. These procedures 

are detailed in STPNOC’s Addendum #5 to procedure No. OPGP03-ZO-0025 Rev. 12 

(Unanticipated Discovery of Cultural Resources) (STPNOC 2008c); the procedure includes 

notification of the SHPO at the THC and affected Tribe(s) or other parties depending on the 

nature of the find. 

Section 9.3.4.1 describes the transmission line corridors. There are no existing transmission 

corridors connecting directly to the Trinity 2 site. However, there are multiple 345-kV 

transmission lines connecting to the Big Brown Power Plant (STPNOC 2010a). A new 

transmission corridor would need to be created to connect the Trinity 2 site to these lines. In the 

event that the Trinity 2 site was chosen for the proposed project, the review team assumes that 

transmission corridor-related cultural resource surveys and procedures would be conducted in a 

manner similar to that for the STP site. In this context, the developer of transmission systems in 

the region, Oncor, would file an Environmental Assessment with the PUCT outlining practices to 

consider community, historic, and aesthetic values and prudent avoidance. During construction 

of such systems, should Oncor or its contractors encounter any archaeological artifacts or other 

cultural resources, work would halt immediately in the vicinity of the resource, the discovery 

would be reported to the THC, and Oncor would take action as directed by the THC. The 

established practice of conducting cultural and historic surveys as part of the Environmental 

Assessment and process for communicating with the THC for inadvertent discoveries ensures 

that offsite cultural and historic resources would be protected. 
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NUREG-1937 9-196 February 2011 

Past actions in the geographic area of interest that have similarly impacted historic and cultural 

resources include rural development and agricultural development and activities associated 

with these land disturbing activities such as road development. One planned project, the 

Tennessee Colony Reservoir, was identified in Table 9-16 that may contribute to cumulative 

impacts on historic and cultural resources in the geographic area of interest. Activities 

associated with building two nuclear units and supporting facilities that can potentially 

destabilize important attributes of historic and cultural resources include land clearing, 

excavation, and grading activities. Given STPNOC’s site planning process and no known 

cultural resources at the Trinity 2 site based on reconnaissance-level information, the impacts to 

cultural resources due to site development activities would be negligible. 

In addition, visual impacts from transmission lines may result in significant alterations to the 

visual landscape within the geographic area of interest. Given that there are no known 

cultural resources where the historic setting and character of the resources are important, 

the visual impacts would be negligible. The review team assumes that the transmission system 

developer, i.e., Oncor, would continue to consider cultural and historic resources and associated 

aesthetic values in a manner consistent with the preparation of Environmental Assessments 

needed to support its filings before the PUCT before an approval is granted. 

Impacts on historic and cultural resources from operation of two new nuclear generating units at 

the Trinity 2 site include those associated with the operation of new units and maintenance of 

transmission lines. The review team assumes that the same procedures currently used by 

STPNOC would be used for onsite and offsite maintenance activities. Consequently, the 

incremental effects of the maintenance of transmission-line corridors and operation of the two 

new units and associated impacts on the cultural resources would be negligible for the physical 

and visual APEs. 

Only one project identified in Table 9-16 could contribute to the cumulative impacts on cultural 

resources within the physical and visual APEs and the geographic area of interest- the 

Tennessee Colony Reservoir. However, reconnaissance-level information indicates that there 

are no known cultural resources in the geographic area of interest, so this new reservoir would 

not significantly affect historic and cultural resources since there are no known resources in the 

geographic area of interest. The impacts of the reservoir would be limited to the visual APE and 

would be similar to those associated with the operation of two new units. 

Cultural resources are non-renewable; therefore, the impact of destruction of cultural resources 

is cumulative. Based on the information provided by the applicant and the review team’s 

independent evaluation, the review team concludes that the cumulative impacts from building 

and operating two new nuclear generating units on the Trinity 2 site and from other projects 

particularly the planned adjacent Tennessee Colony Reservoir, would be SMALL. This impact 

level determination reflects no known cultural resources that could be affected and assumes 

that STPNOC would conduct cultural resource surveys and procedures in a manner similar to 
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February 2011 9-197 NUREG-1937 

that for the STP site. However, if the Tennessee Colony Reservoir or the Trinity 2 site were to 

be developed, then cultural resource surveys may reveal important historic properties that could 

result in greater cumulative impacts. 

9.3.4.8 Air Quality 

The following impact analysis includes impacts from building activities and operations. The 

analysis also considers other past, present, and reasonably foreseeable future actions that 

impact air quality, including other Federal and non-Federal projects listed in Table 9-16. The 

atmospheric emissions related to building and operating a nuclear power plant at the STP site in 

Matagorda County, Texas, are described in Chapters 4 and 5. The criteria pollutants were 

found to have a SMALL impact. In Chapter 7, the cumulative impacts of the criteria pollutants at 

the STP site were evaluated and determined to be MODERATE principally because of a nearby 

major source; absent that source, the cumulative impacts would be SMALL. The geographic 

area of interest for the Trinity 2 site is Freestone County, which is in the Austin-Waco Intrastate 

Air Quality Control Region (40 CFR 81.134). The emissions related to building and operating a 

nuclear power plant at the Trinity 2 site would be similar to those at the STP site. The air quality 

attainment status for Freestone County as set forth in 40 CFR 81.344 reflects the effects of past 

and present emissions from all pollutant sources in the region. Freestone County is not out of 

attainment of any National Ambient Air Quality Standard. 

Reflecting on the projects listed in Table 9-16, the most significant are the Big Brown Power 

Plant, Freestone Energy Center, Lakeside Energy Center, and the Limestone Electric 

Generating Station. Effluents from power plants such these are typically released through 

stacks and with significant vertical velocity. Other industrial projects listed in Table 9-16 would 

have de minimis impacts. Given that these projects would be subject to institutional controls, it 

is unlikely that the air quality in the region would degrade to the extent that the region would be 

in nonattainment of National Ambient Air Quality Standards. 

The air quality impact of Trinity 2 site development would be local and temporary. The distance 

from building activities to the site boundary would be sufficient to generally avoid significant air 

quality impacts. There are no land uses or projects, including the aforementioned source, that 

would have emissions during site development that would, in combination with emissions from 

the Trinity 2 site, result in degradation of air quality in the region. 

Releases from operation of two units at the Trinity 2 site would be intermittent and made at low 

levels with little or no vertical velocity. The air quality impacts of the Big Brown Power Plant, 

Freestone Energy Center, and Units 1 and 2 of the Limestone Electric Generating Station are 

included in the baseline air quality status. The air quality impacts of the Lakeside Energy 

Center would be similar to the air quality impacts discussed in Section 9.2.2.2, and the air 

quality impacts of Unit 3 of the Limestone Electric Generating Station would be similar to the air 

quality impacts discussed in Section 9.2.2.1, which could be noticeable but not destabilizing. 
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The cumulative impacts from emissions of effluents from the Trinity 2 site and the 

aforementioned sources could be noticeable but not destabilizing. 

The cumulative impacts of greenhouse gas emissions related to nuclear power are discussed in 

Section 7.6. The impacts of the emissions are not sensitive to location of the source. 

Consequently, the discussion in Section 7.6 is applicable to a nuclear power plant located at the 

Trinity 2 site. The review team concludes that the national and worldwide cumulative impacts of 

greenhouse gas emissions are noticeable but not destabilizing. The review team further 

concludes that the cumulative impacts would be noticeable but not destabilizing, with or without 

the greenhouse gas emissions of the project at the Trinity 2 site. 

Cumulative impacts to air quality resources are estimated based in the information provided by 

STPNOC and the review team’s independent evaluation. Other past, present and reasonably 

foreseeable future activities exist in the geographic areas of interest (local for criteria pollutants 

and global for greenhouse gas emissions) that could affect air quality resources. The 

cumulative impacts on criteria pollutants from emissions of effluents from the Trinity 2 site, other 

projects, the Big Brown Power Plant, Freestone Energy Center, Lakeside Energy Center, and 

the Limestone Electric Generating Station would be noticeable but not destabilizing, principally 

as a result of the contribution of Unit 3 of the Limestone Electric Generating Station. The 

national and worldwide cumulative impacts of greenhouse gas emissions are noticeable but not 

destabilizing. The review team concludes that the cumulative impacts would be noticeable but 

not destabilizing, with or without the greenhouse gas emissions from the Trinity 2 site. The 

review team concludes that cumulative impacts from other past, present, and reasonably 

foreseeable future actions on air quality resources in the geographic areas of interest would be 

MODERATE for criteria pollutants and MODERATE for greenhouse gas emissions. The 

incremental contribution of impacts on air quality resources from building and operating two 

units at the Trinity 2 site would be insignificant for both criteria pollutants and greenhouse gas 

emissions. 

9.3.4.9 Nonradiological Health 

The following impact analysis includes impacts from building activities and operations. The 

analysis also considers other past, present, and reasonably foreseeable future actions that 

impact nonradiological health, including other Federal and non-Federal projects listed in 

Table 9-16. The building-related activities that have the potential to impact the health of 

members of the public and workers include exposure to dust and vehicle exhaust, occupational 

injuries, noise, and the transport of construction materials and personnel to and from the site. 

The operation-related activities that have the potential to impact the health of members of the 

public and workers includes exposure to etiological agents, noise, EMFs, and impacts from the 

transport of workers to and from the site. For the analysis of nonradiological health impacts at 

the Trinity 2 alternative site, the geographic area of interest is considered to include projects 

within a 5 mi radius from the site’s center based on the localized nature of the impacts. For 
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February 2011 9-199 NUREG-1937 

impacts associated with transmission lines, the geographic area of interest is the transmission 

line corridor. 

Building Impacts 

Nonradiological health impacts to construction workers and members of the public from building 

two new nuclear units at the Trinity 2 site would be similar to those evaluated in Section 4.8 for 

the STP site. The impacts include noise, vehicle exhaust, dust, occupational injuries, and 

transportation accidents, injuries, and fatalities. Applicable Federal and State regulations on air 

quality and noise would be complied with during the site preparation and building phase. The 

incidence of construction worker accidents would not be expected to be different from the 

incidence of accidents estimated for STP. The Trinity 2 site is located in a rural area and 

building impacts would likely be negligible on the surrounding populations. The ER (STPNOC 

2010a) indicated that there may be significant impacts on the transportation network in the 

vicinity of the Trinity 2 site and mitigation would be warranted. The impacts in the vicinity of the 

Trinity 2 site include traffic associated with the Big Brown Power Plant and lignite mine and the 

Fairfield Lake State Park. Interactions between the traffic destined for the Trinity 2 site during 

building and these other projects are likely to increase the nonradiological health effects from 

traffic accidents in the vicinity. The additional injuries and fatalities from traffic accidents 

involving transportation of materials and personnel for building of a new nuclear power plant at 

the Trinity 2 site would be similar to those evaluated in Section 4.8.3 for the STP site and would 

represent a small fraction (less than 5 percent) of the total traffic fatalities in Freestone County. 

Past and present actions in the geographic areas of interest that have similarly affected 

nonradiological resources include the construction and operation of the Big Brown Power Plant 

and the Big Brown Lignite Coal Mine. Proposed future actions would include transmission line 

development and/or upgrading throughout the designated geographic area of interest, and 

future urbanization. These actions would likely result in nonradiological health impacts similar to 

those discussed above for the building of the Trinity 2 site. 

Operational Impacts 

Nonradiological health impacts from operation of two new nuclear units on occupational health 

and members of the public at the Trinity 2 site would be similar to those evaluated in Section 5.8 

for the STP site. Occupational health impacts to workers (e.g., falls, electric shock or exposure 

to other hazards) at the Trinity 2 site would likely be the same as those evaluated for workers at 

two new units at the STP site. Exposure to the public from water-borne etiological agents at the 

Trinity site would be similar to the types of exposures evaluated in Section 5.8.1, and the 

operation of the new units at the Trinity 2 site would not likely lead to an increase in water-borne 

diseases in the vicinity. Noise and EMF exposure would be monitored and controlled in 

accordance with applicable OSHA regulations. Effects of EMF on human health would be 

controlled and minimized by conformance with NESC criteria and adherence to the standards for 
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NUREG-1937 9-200 February 2011 

transmission systems regulated by the PUCT. Nonradiological impacts of traffic associated with 

the operations workforce would be less than the impacts during building. Mitigation measures 

taken during building to improve traffic flow would also minimize impacts during operation, 

The past and present activities in the geographic areas of interest that would have 

nonradiological impacts to the public or workers similar to those discussed for the Trinity 2 site 

include the Big Brown Power Plant and the Big Brown Lignite Coal Mine. Noise from the 

operation of the Trinity 2 site would not likely be discernable to the public at the Fairfield Lake 

State Park, which is closest to the Big Brown Power Plant. Proposed future actions that would 

impact nonradiological health in a similar way to operation activities at the Trinity 2 site would 

include transmission line systems and future urbanization, which would both occur throughout 

the designated geographic areas of interest. 

The review team is also aware of the potential climate changes that could affect human health; 

a recent compilation of the state of the knowledge in this area (GCRP 2009) has been 

considered in the preparation of this EIS. Projected changes in the climate for the region 

include an increase in average temperature and a decrease in precipitation, which may alter the 

presence of microorganisms and parasites in any reservoir that would be used. The review 

team did not identify anything that would alter its conclusion regarding the presence of 

etiological agents or change in the incidence of water-borne diseases. 

Summary 

Based on the information provided by STPNOC and the review team’s independent evaluation, 

the review team expects that nonradiological health impacts from building and operating two 

new units at the Trinity 2 alternative site would be similar to the impacts evaluated for the STP 

site. While there are past, present and future activities in the geographic area of interest that 

could affect nonradiological health in ways similar to the building and operation of two units at 

the Trinity 2 site, those impacts would be localized and managed through adherence to existing 

regulatory requirements. The review team concludes, therefore, that the cumulative impacts 

would be SMALL. 

9.3.4.10 Radiological Impacts of Normal Operations 

The following impact analysis includes radiological impacts to the public and workers from 

building activities and operations for two nuclear units at the Trinity 2 alternative site. The 

analysis also considers other past, present, and reasonably foreseeable future actions that 

impact radiological health, including other Federal and non-Federal projects and those projects 

listed in Table 9-16. As described in Section 9.3.4, the Trinity 2 site is a greenfield site; there 

are currently no nuclear facilities on the site. The geographic area of interest is the area within 

a 50-mi radius of the Trinity 2 site. There are no major facilities that result in regulated 

exposures to the public or biota within the 50-mi radius of the Trinity 2 site. However, there are 
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February 2011 9-201 NUREG-1937 

likely to be hospitals and industrial facilities within 50 mi of the Trinity 2 site that use radioactive 

materials. 

The radiological impacts of building and operating the proposed two ABWR units at the Trinity 2 

site include doses from direct radiation and liquid and gaseous radioactive effluents. These 

pathways would result in low doses to people and biota offsite that would be well below 

regulatory limits. These impacts are expected to be similar to those estimated for the STP site. 

The NRC staff concludes that the dose from direct radiation and effluents from hospitals and 

industrial facilities that use radioactive material would be an insignificant contribution to the 

cumulative impact around the Trinity 2 site. This conclusion is based on data from the 

radiological environmental monitoring programs conducted around currently operating nuclear 

power plants. 

Based on the information provided by STPNOC and the NRC staff's independent analysis, the 

NRC staff concludes that the cumulative radiological impacts from building and operating the 

two proposed ABWRs and other existing and planned projects and actions in the geographic 

area of interest around the Trinity 2 site would be SMALL. 

9.3.4.11 Postulated Accidents 

The following impact analysis includes radiological impacts from postulated accidents from 

operations for two nuclear units at the Trinity 2 alternative site. The analysis also considers 

other past, present, and reasonably foreseeable future actions that impact radiological health 

from postulated accidents, including other Federal and non-Federal projects and those projects 

listed in Table 9-16. As described in Section 9.3.4, Trinity 2 is a greenfield site; there are 

currently no nuclear facilities on the site. The geographic area of interest considers all existing 

and proposed nuclear power plants that have the potential to increase the probability-weighted 

consequences (i.e., risks) from a severe accident at any location within 50 mi of the Trinity 2 

site. There are no existing or proposed reactors that have the potential to increase the 

probability-weighted consequences (i.e., risks) from a severe accident at any location within 

50 mi of the Trinity 2 site. 

As described in Section 5.11.1, the NRC staff concludes that the environmental consequences 

of DBAs at the STP site would be minimal for ABWRs. DBAs are addressed specifically to 

demonstrate that a reactor design is robust enough to meet NRC safety criteria. The ABWR 

design is independent of site conditions, and the meteorology of the Trinity 2 and STP sites are 

similar; therefore, the NRC staff concludes that the environmental consequences of DBAs at the 

Trinity 2 site would be minimal. 

Because the meteorology, population distribution, and land use for the Trinity 2 alternative site 

are expected to be similar to the proposed STP site, risks from a severe accident for an ABWR 

reactor located at the Trinity 2 alternative site are expected to be similar to those analyzed for 
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the proposed STP site. These risks for the proposed STP site are presented in Tables 5-18 and 

5-19 and are well below the median value for current-generation reactors. In addition, estimates 

of average individual early fatality and latent cancer fatality risks are well below the 

Commission’s safety goals (51 FR 30028). On this basis, the NRC staff concludes that the 

cumulative risks of severe accidents at any location within 50 mi of the Trinity 2 alternative site 

would be SMALL. 

9.3.5 Comparison of the Impacts of the Proposed Action and Alternative Sites 

This section summarizes the review team’s characterization of the cumulative impacts related to 

locating a two-unit ABWR nuclear power facility at the proposed STP site and at each 

alternative site. The three sites selected for detailed review as part of the alternative sites 

environmental analysis are the Red 2, Allens Creek, and Trinity 2 sites in Texas. Comparisons 

are made between the proposed and alternative sites to evaluate if one of the alternative sites 

would be environmentally preferable to the proposed site. The NRC’s determination is 

independent of the Corps’ determination of a Least Environmentally Damaging Practicable 

Alternative pursuant to the Clean Water Act Section 404(b)(1) Guidelines at 40 CFR Part 230. 

The Corps will conclude its analysis of both offsite and onsite alternatives in its Record of 

Decision. The Corps onsite alternatives evaluation is discussed in Section 9.5. 

The need to compare the proposed site with alternative sites arises from the requirement in 

Section 102(2)(c)(iii) of NEPA (42 USC 4332) that environmental impact statements include an 

analysis of alternatives to the proposed action. The NRC criteria to be employed in assessing 

whether a proposed site is to be rejected in favor of an alternative site is based on whether the 

alternative site is “obviously superior” or “environmentally preferable” to the site proposed by the 

applicant (Public Service Company of New Hampshire 1977). An alternative site is “obviously 

superior” to the proposed site if it is “clearly and substantially” superior to the proposed site 

(Rochester Gas & Electric Corp. 1978). The standard of obviously superior “...is designed to 

guarantee that a proposed site will not be rejected in favor of an alternate unless, on the basis 

of appropriate study, the Commission can be confident that such action is called for (New 

England Coalition on Nuclear Pollution 1978).” 

The “obviously superior” test is appropriate for two reasons. First, the analysis performed by the 

NRC in evaluating alternative sites is necessarily imprecise. Key factors considered in the 

alternative site analysis, such as population distribution and density, hydrology, air quality, 

aquatic and terrestrial ecological resources, aesthetics, land use, and socioeconomics are 

difficult to quantify in common metrics. Given this difficulty, any evaluation of a particular site 

must have a wide range of uncertainty. Second, the applicant’s proposed site has been 

analyzed in detail, with the expectation that most adverse environmental impacts associated 

with the site have been identified. The alternative sites have not undergone a comparable level 

of detailed study. For these reasons, a proposed site may not be rejected in favor of an 
Environmental Impacts of Alternatives 

February 2011 9-203 NUREG-1937 

alternative site when the alternative site is marginally better than the proposed site, but only 

when it is obviously superior (Rochester Gas & Electric Corp. 1978). NEPA does not require 

that a nuclear plant be constructed on the single best site for environmental purposes. Rather, 

“...all that NEPA requires is that alternative sites be considered and that the effects on the 

environment of building the plant at the alternative sites be carefully studied and factored into 

the ultimate decision (New England Coalition on Nuclear Pollution 1978).” 

Section 9.3.5.1 reviews the cumulative environmental impacts of building and operating a twounit nuclear power plant at the proposed STP site. Cumulative impact levels from Chapter 7 (for 

the proposed STP site), and the three alternative sites (from Sections 9.3.2 through 9.3.4) are 

listed in Table 9-20. Sections 9.3.5.2 and 9.3.5.3 discuss the cumulative impacts of the 

proposed project located at the STP site and at the alternative sites as they relate to a 

determination of environmental preference or obvious superiority. 

9.3.5.1 Comparison of Cumulative Impacts at the Proposed and Alternative Sites 

The following section summarizes the review team’s independent assessment of the proposed 

and alternative sites. The team characterized the expected cumulative environmental impacts 

of building and operating new units at the STP site and alternative sites; these impacts are 

summarized by resource area in Table 9-20. 

The environmental resource areas listed in the following table have been evaluated using the 

NRC’s three-level standard of impact significance: SMALL, MODERATE, or LARGE. These 

levels were developed using the CEQ guidelines and set forth in the footnotes to Table B-1 of 

10 CFR Part 51, Subpart A, Appendix B: 

SMALL – Environmental effects are not detectable or are so minor that they will neither 

destabilize nor noticeably alter any important attribute of the resource. 

MODERATE – Environmental effects are sufficient to alter noticeably, but not to 

destabilize, important attributes of the resource. 

LARGE – Environmental effects are clearly noticeable and are sufficient to destabilize 

important attributes of the resource. 
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NUREG-1937 9-204 February 2011 

Table 9-20. Comparison of Cumulative Impacts at the Proposed and Alternative Sites

Resource Area STP Red 2 Allens Creek Trinity 2 

Land-Use MODERATE MODERATE MODERATE MODERATE 

Water-Related 

 Surface Water Use MODERATE MODERATE MODERATE MODERATE 

 Surface Water Quality MODERATE SMALL SMALL MODERATE 

Groundwater Use SMALL MODERATE SMALL MODERATE 

Groundwater Quality SMALL SMALL to 

MODERATE 

SMALL SMALL 

Ecology 

 Terrestrial Ecosystems MODERATE MODERATE MODERATE MODERATE 

 Aquatic Ecosystems MODERATE MODERATE MODERATE MODERATE 

to LARGE 

Socioeconomic* 

 Physical SMALL SMALL SMALL to 

MODERATE 

SMALL to 

MODERATE 

 Demography SMALL to 

MODERATE 

SMALL to 

MODERATE 

SMALL to 

LARGE 

MODERATE 

to LARGE 

 Taxes and Economy SMALL to 

LARGE 

BENEFICIAL 

 SMALL to 

LARGE 

BENEFICIAL 

SMALL to 

LARGE 

BENEFICIAL 

SMALL to 

LARGE 

BENEFICIAL 

 Housing and Transportation SMALL to 

MODERATE 

SMALL to 

MODERATE 

 MODERATE 

to LARGE 

 MODERATE 

to LARGE 

 Public Services and Education SMALL to 

MODERATE 

SMALL to 

LARGE 

MODERATE 

to LARGE 

MODERATE 

to LARGE 

 Aesthetics and Recreation SMALL to 

MODERATE 

SMALL to 

MODERATE 

MODERATE SMALL to 

MODERATE 

Environmental Justice SMALL SMALL SMALL to 

LARGE 

SMALL 

Historic and Cultural Resources SMALL SMALL LARGE SMALL 

Air Quality MODERATE SMALL to 

MODERATE 

SMALL to 

MODERATE 

MODERATE 

Nonradiological Health SMALL SMALL SMALL SMALL 

Radiological Health SMALL SMALL SMALL SMALL 

Postulated Accidents SMALL SMALL SMALL SMALL 

*ranges indicate differences in counties 
Environmental Impacts of Alternatives 

February 2011 9-205 NUREG-1937 

Full explanations for the specific cumulative impact characterizations are provided in Chapter 7 

for the proposed site and in Sections 9.3.2, 9.3.3, and 9.3.4 for the alternative sites. The review 

team’s impact category levels are based on professional judgment, experience, and 

consideration of controls likely to be imposed under required Federal, State, or local permits that 

would not be acquired until an application for a COL is underway. The considerations and 

assumptions were similarly applied at each of the alternative sites to provide a common basis 

for comparison. In the following discussion, the review team compares the impact levels 

between the proposed site, and each alternative site. 

9.3.5.2 Environmentally Preferable Sites 

As shown in Table 9-20, the cumulative impacts of building and operating two new units at the 

proposed site and the alternative sites vary across the impact categories. The resource 

categories for which the impact level at an alternative site is the same as that for the proposed 

site does not contribute to the alternative site being judged to be environmentally preferable to 

the proposed site. Therefore, these categories are not discussed further in determining whether 

an alternate site is environmentally preferable to the proposed site. The categories for which an 

alternative site has a different impact level than the proposed site are discussed further to 

determine if an alternative site is environmentally preferable to the proposed site. Where there 

is a range of impacts for a resource, the upper value of the impacts is used for the comparison. 

In addition, for those cases in which the cumulative impacts for a resource are greater than 

SMALL, consideration is given to those cases in which the impacts of the project at the specific 

site do not make any significant contribution to the cumulative impact level. As shown in 

Table 9-20, there are some differences in impacts among the sites. 

Red 2 Site

The STP site is characterized more favorably than the Red 2 site in Table 9-20 for the following 

resource areas: groundwater use and quality and public services and education. The Red 2 

site is characterized more favorably than the STP site for surface water quality and air quality. 

For the resource areas for which the STP site is characterized more favorably, building and 

operating two new nuclear units at the Red 2 site would be a significant contributor to the higher 

impact level. Therefore, the differences in impacts for these two resource areas are meaningful 

to the comparison of the sites. For surface water quality, the MODERATE impact at the STP 

site is based on pre-existing conditions. Building and operating two new nuclear units at the 

STP would not contribute significantly to surface water quality impacts. For air quality at both 

sites, the MODERATE impacts are based on the effects of projects other than the nuclear units. 

Nuclear plants don’t contribute significantly to air quality impacts. So the apparent differences in 

impacts for these resources are not meaningful in terms of the proposed action. 

For land use, surface water use, and terrestrial and aquatic ecosystems, although the two sites 

have essentially the same cumulative impact levels, the two new nuclear units would not be a 
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NUREG-1937 9-206 February 2011 

significant contributor to the impact level at the STP site. This is because a reservoir already 

exists at the STP site, and there would be little in-water construction in the Colorado River. The 

project would be a significant contributor to the MODERATE cumulative impacts to these 

resources at the Red 2 site because it is a greenfield site with no existing facilities to be shared 

with new units. A similar situation exists for aesthetics and recreation – the project would not be 

a significant contributor to the SMALL to MODERATE impacts at the STP site, but it would be at 

the Red 2 site. Again, these differences favor the STP site. 

Based on the results and comparison of the impact characterizations, the review team 

concludes that the Red 2 site would not be environmentally preferable to the STP site for two 

new nuclear generating units. 

Allens Creek Site

The STP site is characterized more favorably than the Allens Creek site in Table 9-20 for the 

following resource areas: physical impacts, demography, housing and transportation, public 

services and education, aesthetics and recreation, environmental justice, and historic and 

cultural resources. Conversely, the Allens Creek site is characterized by the review team as 

more favorable than the STP site in Table 9-20 for surface water quality and air quality. For 

physical and environmental justice impacts, the primary reason for the higher impacts at the 

Allens Creek site is the proposed I-69, a new highway to be constructed along the general route 

of U.S. 59. Building and operating two new nuclear units at the Allens Creek site would not 

contribute significantly to the impact levels. For the remainder of the impact areas for which the 

STP is characterized more favorably, building and operating two new nuclear units at the Allens 

Creek site is a significant contributor to the higher impact levels, and so the differences in 

impact levels are meaningful to the comparison of the sites. For surface water quality, the 

MODERATE impact at the STP site is based on pre-existing conditions. Building and operating 

two new nuclear units at the STP would not contribute significantly to surface water quality 

impacts. For air quality at both sites, the MODERATE impacts are based on the effects of 

projects other than the nuclear units. Nuclear plants don’t contribute significantly to air quality 

impacts. So the apparent differences in impacts for these resources are not meaningful in 

terms of the proposed action. 

For land use and terrestrial ecosystems, although the two sites have essentially the same 

cumulative impact levels, the two new nuclear units would not be a significant contributor to the 

impact level at the STP site (i.e., the MODERATE impacts are based on the effects of other 

projects). This is because a reservoir already exists at the STP site and there would be little inwater construction in the Colorado River. But the project would be a significant contributor to 

the MODERATE cumulative impacts for these resources at the Allens Creek site because it is a 

greenfield site with no existing facilities to be shared with new units. 
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February 2011 9-207 NUREG-1937 

Based on comparison of the impact characterizations in Table 9-20, the review team concludes 

that the Allens Creek site would not be environmentally preferable to the STP site for two new 

nuclear generating units. 

Trinity 2 Site

The STP site is characterized more favorably than the Trinity 2 site in Table 9-20 for the 

following resource areas: groundwater use, aquatic ecosystems, physical impacts, demography, 

housing and transportation, and public services and education. Conversely, the Trinity 2 site is 

not characterized by the review team as more favorable than the STP site in Table 9-20 for any 

resource area. For physical impacts, the higher impacts at the Trinity 2 site relate to other 

projects in the area and the project at the Trinity 2 site would not contribute significantly to the 

impact level. For all of the other impact areas for which the STP site is characterized more 

favorably, the differences relate directly to the impacts of the proposed project at the two sites. 

For land use, surface water use, and terrestrial ecosystems, although the two sites have 

essentially the same cumulative impact levels, the two new nuclear units would not be a 

significant contributor to the impact level at the STP site. This is because a reservoir already 

exists at the STP site and there would be little in-water construction in the Colorado River. But 

the project would be a significant contributor to the MODERATE cumulative impacts for these 

resources at the Trinity 2 site because it is a greenfield site with no existing facilities to be 

shared with new units. For air quality at both sites, the MODERATE impacts are based on the 

effects of projects other than the nuclear units. Nuclear plants do not contribute significantly to 

air quality impacts. 

Based on comparison of the impact characterizations in Table 9-20, the review team concludes 

that the Trinity 2 site would not be environmentally preferable to the STP site for two new 

nuclear generating units. 

Although there are differences and distinctions between the cumulative environmental impacts 

of building and operating two new nuclear generating units at the proposed STP site and the 

alternative sites, the review team concludes that none of these differences is sufficient to 

determine that any of the alternative sites would be environmentally preferable to the proposed 

site for building and operating two new nuclear generating units. 

9.3.5.3 Obviously Superior Sites 

None of the alternative sites were determined to be environmentally preferable to the proposed 

STP site. Therefore, the NRC staff concludes that none of the alternative sites would be 

obviously superior to the STP site. The Corps will conclude its analysis of both offsite and 

onsite alternatives in its Record of Decision. 
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NUREG-1937 9-208 February 2011 

9.4 System Design Alternatives 

The NRC staff considered a variety of heat dissipation systems and circulating water systems 

alternatives. While other heat dissipation systems and water systems exist, by far the largest 

and the most likely to dominate the environmental consequences of operation is the CWS that 

cools and condenses the steam for the turbine-generator. Other water systems, such as 

service water system, are much smaller than the CWS. As a result, the review team only 

considers alternative heat dissipation and water treatment systems for the CWS. The proposed 

CWS is a closed loop system that uses the existing MCR for heat dissipation (STPNOC 2010a). 

The proposed system is discussed in detail in Chapter 3. 

9.4.1 Heat Dissipation Systems 

About two-thirds of the heat from a commercial nuclear reactor is rejected as heat to the 

environment. The remaining one-third of the reactor’s generated heat is converted into 

electricity. Normal heat sink cooling systems transfer the rejected heat load into the 

atmosphere and/or nearby water bodies, primarily as latent heat exchange (evaporating water) 

or sensible heat exchange (warmer air or water). Different heat-dissipation systems rely on 

different exchange processes. The following sections describe alternative heat dissipation 

systems considered by the NRC staff for proposed Units 3 and 4 at the STP site. 

The impacts associated with the proposed heat dissipation system, a cooling pond or reservoir, 

are discussed in Sections 4.2, 4.3, 5.2, and 5.3. STPNOC proposes to use the existing MCR as 

the heat dissipation system for the proposed units. The review team determined in Chapter 4 

that the impacts of building the proposed heat dissipation system would be SMALL for both 

hydrologic and ecological resources. The review team also determined in Chapter 5 that the 

impacts of operating the proposed heat dissipation system would be SMALL for both hydrologic 

and ecological resources. 

STPNOC considered a range of heat dissipation systems in its ER including a once-through 

cooling system and several closed-cycle cooling systems. In addition to the closed-cycle MCR 

selected, STPNOC also considered spray canals, mechanical draft wet cooling towers, natural 

draft wet cooling towers, a combination wet/dry cooling tower system, fan-assisted natural draft 

cooling towers and dry cooling towers (STPNOC 2010a). The NRC staff considered these 

options as well as once-through cooling with a helper tower cooling system that would be used 

under high receiving water body temperature conditions. 

9.4.1.1 Plant Cooling System – Once-Through Operation 

Once-through cooling systems withdraw water from the source water body and return virtually 

the same volume of water to the receiving water body at an elevated temperature. Typically the 
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February 2011 9-209 NUREG-1937 

source water body and the receiving water body are the same body, and the intake and 

discharge structures are separated to limit recirculation. While there is essentially no 

consumptive use of water in a once-through heat-dissipation system, the elevated temperature 

of the receiving water body would result in some induced evaporative loss that decreases the 

net water supply. The large intake and discharge flows associated with once-through cooling 

systems require large intake and discharge structures; the high flow rates may result in 

hydrological alterations in the source/receiving water bodies. In addition, the high flow rates 

result in higher levels of impingement and entrainment of aquatic organisms. Based on 

EPA 316(b) Phase I regulations (66 FR 65255), the NRC staff has determined that oncethrough cooling systems for new nuclear reactors are unlikely to be permitted in the future, 

except in rare and unique situations. 

The STP site is approximately 10 mi from the Matagorda Bay on the Gulf of Mexico (STPNOC 

2010a), the closest body of water that potentially could support once-through cooling. The NRC 

staff determined that once-through cooling would not be an environmentally preferable 

alternative because of the magnitude of the impacts of building large intake and discharge 

structures and associated piping linking these structures with the plant. Furthermore, oncethrough cooling would require a significant volume of makeup water and could potentially have 

significant impacts on sensitive aquatic biota of Matagorda Bay. 

9.4.1.2 Spray Canals 

Spray canal cooling systems circulate water in man-made canals and enhance evaporative 

cooling by spraying water into the atmosphere. In addition to evaporation, heat transfer from 

the spray canals to the atmosphere also occurs through black-body radiation and conduction. 

A spray canal system alternative was evaluated by STPNOC for cooling STP Units 1 and 2 and 

was found to require an effective canal length of 20,250 ft and a width of 200 ft which would 

require 150 ac. An additional 680 acres would be required for the intake canal corridor 

(STPNOC 2010a). The NRC staff independently evaluated the system design requirements 

and determined that the size and dimensions were calculated consistent with the heat rejection 

requirements. Since the evaporation from a new spray canal would be greater than the induced 

evaporation of the existing MCR, the consumptive water use of a spray canal would be greater 

than the proposed alternative. Because no additional land would need to be disturbed for the 

proposed alternative and because of increased consumptive use of water in a spray canal the 

NRC staff concluded that use of a spray canal would not be an environmentally preferable 

alternative for the STP site. 

9.4.1.3 Wet Mechanical Draft Cooling Towers 

A wet mechanical draft cooling tower transfers heat to the environment via evaporation and 

conduction. These towers can be relatively low profile compared to natural draft towers, and 

rely on large fans to force air through walls of falling water. Drift abatement features in the 
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NUREG-1937 9-210 February 2011 

design limit the amount of water suspended as droplets in the air, which may be deposited on 

the ground outside the tower. Wet mechanical draft towers often generate visible plumes when 

the moisture in air from the cooling tower exhaust cools and the moisture condenses. 

This alternative would require six towers to be built (three towers for each unit), each containing 

12 cells. STPNOC indicates that approximately 70 ac would be required for the towers and an 

additional 630 ac would be required for the intake canal corridor (STPNOC 2010a). The NRC 

staff independently evaluated the system design requirements and determined that the size and 

dimensions were calculated consistent with the heat rejection requirements. Since the 

evaporation of a wet mechanical draft cooling tower is greater than the induced evaporation of a 

cooling pond, the consumptive water use of a wet mechanical draft cooling tower is greater than 

the proposed alternative. Therefore, based on consideration of the land area that would be 

disturbed and the increase in consumptive water use, the NRC staff concluded that building and 

operating wet mechanical draft cooling towers would not be an environmentally preferable 

alternative for the STP site. 

9.4.1.4 Wet Natural Draft Cooling Towers 

Wet natural draft cooling towers induce airflow up through large (500 ft tall and 400 ft in 

diameter) towers by cascading warm water downward in the lower portion of the cooling tower. 

As heat transfers from the water to the air in the tower, the air becomes more buoyant and rises. 

This buoyant circulation induces more air to enter the tower through its open base. The size of 

the cooling towers results both in a large visual and land-use footprint. STPNOC indicates that 

approximately 80 ac would be required for the towers and an additional 630 ac would be 

required for the intake canal corridor (STPNOC 2010a). The NRC staff independently evaluated 

the system design requirements and determined that the size and dimensions were calculated 

consistent with the heat rejection requirements. Since the evaporation of a wet natural draft 

cooling tower is greater than the induced evaporation of a cooling pond, the consumptive water 

use of a wet natural draft cooling tower is greater than the proposed alternative. Therefore, 

based on consideration of the land area that would be disturbed for the tower footprints, the 

increase in consumptive water use, and the available cooling capacity of the existing cooling 

reservoir to dissipate heat for two additional units, the NRC staff concluded that building and 

operating wet natural draft cooling towers would not be an environmentally preferable 

alternative for the STP site. 

9.4.1.5 Dry Cooling Towers 

Dry cooling towers would eliminate all water-related impacts from the cooling system operation. 

No makeup water would be needed, and no blowdown water would be generated. However, 

dry cooling systems require much larger cooling systems, and result in both a loss in electrical 

generation efficiency (because the theoretical approach temperature is limited to the dry-bulb 

temperature and not the lower wet-bulb temperature) and greater parasitic energy losses for the 
Environmental Impacts of Alternatives 

February 2011 9-211 NUREG-1937 

large array of fans involved. This loss in generation efficiency translates into increased fuel 

cycle impacts. Because the impacts associated with aquatic ecology, water use, and water 

quality for the proposed cooling system were found to be SMALL (see Chapters 4 and 5), the 

NRC staff determined that, although dry cooling eliminates water-related impacts, it is not 

environmentally preferred to the proposed alternative. 

9.4.1.6 Combination Wet/Dry Cooling Tower System 

A combination mechanical draft wet/dry cooling tower system uses both wet and dry cooling 

cells to limit consumption of cooling water, often with the added benefit of reducing plume 

visibility. Water used to cool the turbine generators generally passes first through the dry 

portion of the cooling tower where heat is removed by drawing air at ambient temperature over 

tubes through which the water is moving. Cooling water leaving the dry portion of the tower 

then passes through the wet tower where the water is sprayed into a moving air stream and 

additional heat is removed through evaporation and sensible heat transfer. When ambient air 

temperatures are low, the dry portion of these cooling towers may be sufficient to meet cooling 

needs. The use of the dry portion of the system would result in a loss in generating efficiency 

that would translate into increased fuel cycle impacts. Although a combination mechanical draft 

wet/dry cooling tower system could reduce water-related impacts, the NRC staff determined that 

the impacts associated with aquatic ecology, water use, and water quality for the building and 

operating the proposed cooling system were SMALL. The NRC staff concluded that building 

and operating a combination wet/dry cooling tower system would not be an environmentally 

preferable alternative for the STP site. 

9.4.2 Circulating Water Systems 

The NRC staff evaluated alternatives to the proposed intakes and discharges for the normal 

heat sink cooling system, based on the proposed heat dissipation system water requirements. 

The capacity requirements of the intake and discharge system are defined by the recommended 

heat dissipation system. For Units 3 and 4, the proposed heat dissipation system is a closedloop system that uses the existing MCR for heat dissipation. 

9.4.2.1 Intake Alternatives 

The impacts associated with the proposed intake system, the reservoir makeup pumping facility 

(RMPF), are discussed in Sections 4.2, 4.3, 5.2, and 5.3. STPNOC proposes to use the 

existing RMPF as the intake system for the proposed units. The review team determined in 

Chapter 4 that the impacts of building the proposed intake system would be SMALL for both 

hydrologic and ecological resources. The review team determined in Chapter 5 that the impacts 

of operating the proposed intake system would be SMALL for both hydrologic and ecological 

resources. 
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NUREG-1937 9-212 February 2011 

The existing intake structure, the RMPF, for the STP site was originally designed to support four 

units. As a result, no additional excavation and building is required to meet the needs of the two 

proposed units. The existing intake structure would be refurbished with new pumps and 

traveling screens in the existing structure (STPNOC 2010a). A redesigned intake structure that 

extends into the river or radial collector wells are alternatives to the current structure for 

obtaining makeup water for the MCR. 

An intake structure that extends into the river has an advantage if other structures on the 

shoreline would conflict with a shoreline intake or if bathymetry or vegetation considerations 

make a shoreline intake less desirable. At the STP site, the conditions that would make an 

offshore intake advantageous do not occur. Offshore intakes with submerged passive screens 

are also more difficult to maintain. The shoreline option is preferable to an offshore intake 

because the intake structure is already in place. 

A radial collector-well system was considered by the NRC staff because in many cases it 

reduces the impact on aquatic resources and, when water is being withdrawn from turbid 

environments can reduce the water treatment needed before its introduction into the cooling 

system. A radial collector-well system consists of an excavated central concrete caisson with 

well screens projected laterally outward in a radial pattern (Riegert 2006). Radial collector wells 

slowly draw surface water through the subsurface layer and, thereby, filter out some sediment 

that might have required treatment if the water had been directly withdrawn from the surface 

water body. In general, collecting surface water in this way eliminates most of the direct 

operational impacts on aquatic ecosystems (e.g., entrainment and impingement) associated 

with water withdrawal. The NRC staff determined that radial collector wells, which would induce 

flow through the sediments of the Colorado River into lateral subterranean pipes extending from 

the shoreline out beneath the reservoir, would require multiple large structures near the 

shoreline. STPNOC did not consider this alternative water source, but the NRC staff 

independently determined that a radial collector-well system would not be environmentally 

preferable to the proposed direct withdrawal from the river due to the environmental impacts 

associated with excavating the caissons, drilling the laterals and building the multiple new 

shoreline structures, and because the impacts associated with aquatic ecology for the proposed 

intake have been determined to be SMALL in Chapters 4 and 5. 

Because the RMPF already exists, the NRC staff concludes that there would be no alternative 

intake designs that would be environmentally preferable to the proposed intake design for the 

STP site. 

9.4.2.2 Discharge Alternatives 

The impacts associated with the proposed discharge system are discussed in Sections 4.2, 4.3, 

5.2, and 5.3. STPNOC proposes to use the existing discharge system as the discharge system 

for the proposed units. The review team determined in Chapter 4 that the impacts of building 
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February 2011 9-213 NUREG-1937 

the proposed discharge system would be SMALL for both hydrologic and ecological resources. 

The review team determined in Chapter 5 that the impacts of operating the proposed discharge 

system would be SMALL for both hydrologic and ecological resources. 

The MCR discharges to the Colorado River through the existing discharge structure. This 

system includes a 1.1-mi-long discharge line that extends downstream along the river bank. 

Releases to the river would occur through one or more of seven discharge ports 

(STPNOC 2010a). The review team determined that the impacts of operation of this system 

would be SMALL and that any other alternative would result in land disturbing and in-water 

activities. Therefore, the NRC staff concluded that there were no alternative discharge designs 

that would be environmentally preferable to the proposed discharge design at the STP site. 

9.4.2.3 Water Supplies 

The impacts associated with the proposed water supply, the Colorado River, are discussed in 

Sections 4.2, 4.3, 5.2, and 5.3. Since the applicant does not propose to use surface water for 

building the proposed units, the review team determined in Chapter 4 that the impacts of 

building the proposed units would be SMALL for both hydrologic and ecological resources. The 

review team determined in Chapter 5 that the impacts of withdrawing water to operate the 

proposed units would be SMALL for both hydrologic and ecological resources. 

The NRC staff considered alternative sources for the circulating water system including water 

reuse, groundwater, and surface water, including both freshwater and saltwater. 

Water Reuse 

Sources of water for reuse can either come from the plant itself or from other local water users. 

Sanitary waste water treatment plants generally used by communities with modest sized 

populations are the most ubiquitous source of water for reuse. Agricultural processing, 

industrial processing, and oilfield production can also provide significant supplies of water for 

reuse. Additional treatment (e.g., tertiary treatment, chlorination) may be required to provide 

water of appropriate quality for the specific plant need. Population is very low and there is little 

industry around the STP site. Consequently, the NRC staff determined that sufficient sources of 

water for reuse do not exist near the STP site. Therefore, the NRC staff concluded that water 

reuse would not be a feasible alternative for water supply at the STP site. 

Groundwater 

STPNOC proposes to use groundwater for the Ultimate Heat Sink (UHS) system during 

operation, but not the circulating water system. The UHS system discharges, sanitary waste, 

liquid radwaste, and wastewater retention basin effluents result in approximately 500 gpm of 

water being made available to make up for evaporative losses from the MCR. The NRC staff 
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NUREG-1937 9-214 February 2011 

did consider groundwater as an alternative water source for the remainder of the makeup water 

for the circulating water system. Existing groundwater wells at the STP site are limited to a 

pumping rate of 500 gpm under the CPGCD Operating Permit and must be separated by 2500 ft 

from neighboring Deep Aquifer wells owned by different permit holders. The review team 

estimated that withdrawal of the quantities of water needed to supply makeup water to the 

circulating water system (22,799 gpm for normal operating conditions, 47,489 gpm maximum) 

would require 95 wells for the maximum demand case. Based on the size and configuration of 

the existing STP site the review team concluded that it is not practical to locate this number of 

wells on the existing STP site without incurring significant interference among adjacent wells. 

The review team estimates that if 100 wells were placed in a square grid separated by 2500 ft, it 

would require more than 18 square mi. 

The STPNOC states (STPNOC 2008b) that the Lower Colorado Regional Water Planning 

Group (LCRWPG) is currently making plans for the conjunctive use of groundwater and surface 

water to effectively use and preserve available water resources. The planning group advocates 

the combined use of these two resources in ways that would minimize the use of groundwater 

when surface water is available and that would manage aquifers for sustainable yield (LCRWPG 

2006). The water management plans document an interest in minimizing the use of 

groundwater rather than utilization. Because it would take an additional 95 wells to meet the 

maximum demand for makeup water for cooling and water management plans for this region 

call for minimizing the use of groundwater, the NRC staff determined that groundwater use for 

CWS makeup water would not be an environmentally preferable alternative for water supply at 

the STP site. 

Surface water 

Surface water supplies at the STP site are saltwater from Matagorda Bay, brackish water from 

the estuarine portion of the Colorado River or fresh water from the Colorado River upstream of 

the dam at Bay City. 

Use of salt water from the Matagorda Bay would require a new intake structure to be built and 

an 18-mi pipeline to transport the water from the Bay to the STP site to be installed (STPNOC 

2010a). To obtain fresh water from the Colorado River upstream of the Lower Colorado River 

Authority dam near Bay City would also require a new intake structure and a pipeline to 

transport the water between the intake and the STP site to be built. The NRC staff determined 

that, while there is an abundant supply of water from Matagorda Bay and from the Colorado 

River upstream of the Lower Colorado River Authority dam, selection of either of these two 

alternatives would result in environmental impacts in many resource areas due to the 

construction of intake structures and the associated pipelines. Therefore, the NRC staff 

concluded that none of the surface water supply alternatives is environmentally preferable for 

the proposed water source for the STP site. 
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February 2011 9-215 NUREG-1937 

9.4.2.4 Water Treatment 

Both inflow and effluent water may require treatment to ensure that it meets plant water needs 

and effluent water standards. STPNOC proposes to add chemicals to plant water to meet 

appropriate water quality process needs. The effluent water chemistry is regulated by the 

TCEQ through the TPDES permitting process. Mechanical treatment may be a viable option for 

scale and biofilm removal. Other alternatives to manage biofouling, such as UV treatment, are 

also feasible. These alternatives, while feasible, would not eliminate the need for some 

chemical treatment. Chemical treatment is a reliable and well-established engineering practice 

that has been shown to provide minimal impacts in a variety of settings. The NRC staff 

identified no environmentally preferable alternative to STPNOC’s proposed chemical water 

treatment. The effluents from cooling tower blowdown are specifically regulated in 40 CFR 423 

by the EPA to protect the environment. In the State of Texas, this regulatory authority is 

administered by the TCEQ. 

9.4.3 Conclusion 

The NRC staff considered alternative systems designs including seven alternative heat 

dissipation systems and alternative intake, discharge, and water supply systems. As discussed 

in the above sections, the NRC staff identified no alternative that was environmentally 

preferable to the proposed plant systems design. 

9.5 Corps’ Onsite Alternatives Evaluation 

A key provision of the 404(b)(1) guidelines is the “practicable alternative test” that requires that 

“no discharge of fill material shall be permitted if there is a practicable alternative to the 

proposed fill which would have a less adverse impact on the aquatic ecosystem” 

(40 CFR 230.10(a)). This is especially true when the proposed project is not water-dependent. 

The applicant must demonstrate that there are no less-damaging alternatives available and that 

all onsite impacts to waters of the United States have been avoided to the maximum practicable 

extent possible. For an alternative to be considered “practicable,” it must be available and 

capable of being done after taking into consideration cost, existing technology, and logistics in 

light of the overall project purpose. STPNOC proposes to construct an off-loading facility and 

heavy haul roads for oversized equipment associated with the construction and operation of the 

proposed nuclear power generation facility. 

9.5.1 Onsite Alternative 1

Onsite alternative 1 uses a railway system as ingress for large equipment and use of existing 

roads within the STP facility to offload and transport heavy materials. This alternative would 

require the construction of 12 mi of rail line, which may cost between $10 and $15 million. 
Environmental Impacts of Alternatives 

NUREG-1937 9-216 February 2011 

Construction of the railway may require up to a 100-ft right-of-way, or 145 ac, which may include 

impacts to waters, uplands, and public infrastructure such as overhead utility lines, potable 

water, and sewer lines. Use of existing roads to transport materials after offloading from the 

railcars would be strictly limited due to safety concerns to human health and risk. 

9.5.2 Onsite Alternative 2

Onsite alternative 2 includes barging material up the existing Colorado River Navigation 

Channel, but not dredging the existing barge terminal. In this alternative, a large crane would 

be used to offload material from the barges, which could be located within the Colorado River. 

The cost of the crane is estimated to be $12 million. Barge traffic staged in the river for 

offloading may impede commercial and recreational navigation in the river during staging and 

offloading. Use of upgraded roads to transport materials after offloading from the barge would 

be strictly limited due to safety concerns to human health and risk. Limited impacts to waters, 

uplands, or public infrastructure are anticipated by this alternative. 

9.5.3 Onsite Alternative 3 (STPNOC’s Preferred Alternative)

Onsite alternative 3 uses a combination of barging material up the existing Colorado River 

Navigation Channel, upgrading existing barge slips to unload heavy equipment and construction 

of a heavy haul road within the STP facility. The existing barge slips are silted-in and would 

require dredging and rehabilitation before use. STPNOC has proposed to increase the capacity 

of the barge slips to accommodate larger barges. Excavation and dredging of material would be 

conducted utilizing mechanical dredge methods and all materials would be placed in an existing 

upland dredge material placement area located onsite. Offloading of material would occur 

within the barge slip, and no impacts to navigation are expected during staging and offloading. 

A heavy haul road would be constructed from the barge slip to the construction site. The heavy 

haul road would require six culverted crossings within channelized streams. Properly sized and 

placed culverts may result in both positive and negative stream impacts. Culverts may disrupt 

the geomorphology of the stream, but also provide shade for aquatic species. The streams 

proposed for crossing are channelized and devoid of riparian buffer. The estimated cost of 

excavation and expansion of the existing barge slip and construction of the heavy haul road is 

$1 million. 

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U.S. Nuclear Regulatory Commission (NRC). 1996. Generic Environmental Impact Statement 

for License Renewal of Nuclear Plants. NUREG-1437, Vol. 1 and 2, Washington, D.C. 

U.S. Nuclear Regulatory Commission (NRC). 1998. General Site Suitability Criteria for Nuclear 

Power Stations. Regulatory Guide 4.7, Rev. 2, Washington, D.C. Accession No. 

ML003739894. 

U.S. Nuclear Regulatory Commission (NRC). 1999. Generic Environmental Impact Statement 

for License Renewal of Nuclear Plants Main Report, “Section 6.3 – Transportation, Table 9.1, 

Summary of findings on NEPA issues for license renewal of nuclear power plants, Final Report.” 

NUREG-1437, Volume 1, Addendum 1, Washington, D.C. Accession No. ML040690720. 

U.S. Nuclear Regulatory Commission (NRC). 2000. Environmental Standard Review Plan—

Review Plans for Environmental Reviews for Nuclear Power Plants. NUREG-1555, 

Washington, D.C. Includes 2007 updates. 
Environmental Impacts of Alternatives 

NUREG-1937 9-238 February 2011 

U.S. Nuclear Regulatory Commission (NRC). 2008a. Letter from Paul Kallan, NRC, to Gregory 

Gibson, STPNOC, dated May 19, 2008, “Request for Additional Information, Letter Number One 

Related to the Environmental Report for the South Texas Combined License Application.” 

Accession No. ML081360531. 

U.S. Nuclear Regulatory Commission (NRC). 2008b. Letter from Paul Kallan, NRC, to Scott 

Head, STPNOC, dated November 18, 2008, “Request for Additional Information, Letter Number 

Two Related to the Environmental Report for the South Texas Combined License Application.” 

Accession No. ML083190269. 

U.S. Nuclear Regulatory Commission (NRC). 2009. Site Audit Summary of South Texas 

Project Nuclear Operating Company’s Revised Alternative Sites Analysis. November 9, 2009. 

Washington, D.C. Accession No. ML092870574. 

U.S Nuclear Regulatory Commission (NRC). 2010. Staff Memorandum from Scott Flanders, 

DSER Division Director, to Brent Clayton, RENV Branch Chief, dated December 10, 2010, 

“Additional guidance on conducting environmental reviews is provided in Staff Memorandum on 

Addressing Construction and Preconstruction, Greenhouse Gas Issues, General Conformity 

Determinations, Environmental Justice, Need for Power, Cumulative Impact Analysis, and 

Cultural/Historical Resources Analysis Issues in Environmental Impact Statements.” Accession 

No. ML100760503. 

United States Steel (USS). 2009. Bellville Operations Division. Pittsburgh, Pennsylvania. 

Accessed March 5, 2010 at http://www.ussteel.com/corp/facilities/Bellville.asp. 

University of Texas (UT). 1996. Physiography of Texas. Accessed October 21, 2009 at 

http://www.lib.utexas.edu/geo/physiography.html. The Walter Geology Library, University of 

Texas at Austin, Austin, Texas. 

Upper Trinity Regional Water District. (UTRWD). 2010. Upper Trinity Regional Water District's 

Diversified Water Portfolio: Lake Ralph Hall. Accessed March 5, 2010 at 

http://www.lakeralphhallinfo.com. Lewisville, Texas. 

Virtus Energy (Virtus). 2008. Texas Renewable Energy Assessment: Geothermal. Accessed 

February 25, 2009 at http://www.vera.com/re_b_psdoc_07.htm. Austin, Texas. 

Wade, S.C. 2008. GAM Run 08-14mag. Texas Water Development Board, Groundwater 

Availability Modeling Section, Austin, Texas. May 6, 2008. Accessed November 15, 2009 at 

http://www.twdb.state.tx.us/GwRD/GMA/MAG/GMA8_GR08-14mag.pdf. Accession No. 

ML100700550. 
Environmental Impacts of Alternatives 

February 2011 9-239 NUREG-1937 

Wood, C.R., T.L. Arsuffi and M.K. Cauble. 1994. Macroinvertebrate assessment of Allens 

Creek and the Brazos River, Austin County, Texas. River Studies Report No. 11, Texas Water 

Develoment Board Interagency Contract Number 93-483-364. Texas Parks and Wildlife 

Department, Austin, Texas. 

Conclusions and Recommendations 

February 2011 10-1 NUREG-1937 

10.0 Conclusions and Recommendations 

The U.S. Nuclear Regulatory Commission (NRC or the Commission) received an application 

from STP Nuclear Operating Company (STPNOC) for combined construction permits and 

operating licenses (combined licenses or COLs) for South Texas Project Electric Generating 

Station (STP) Units 3 and 4. The location of the proposed Units 3 and 4 is approximately 

2000 ft northwest of the existing STP Units 1 and 2. The STP site and existing facilities are 

owned by NRG Energy, Inc. (NRG); City Public Service Board of San Antonio, Texas (CPS 

Energy); and the City of Austin, Texas. It is planned that STP Unit 3 would be owned by 

Nuclear Innovation North America (NINA) Texas 3 LLC and CPS Energy, and STP Unit 4 would 

be owned by NINA Texas 4 LLC and CPS Energy (STPNOC 2010a). STPNOC would be the 

licensed operator for the proposed Units 3 and 4, as it currently is for the existing Units 1 and 2. 

In its application, STPNOC specified the certified U.S. Advanced Boiling Water Reactor 

(ABWR), as modified by STPNOC’s proposed amendment to the ABWR design (STPNOC 

2010b), as the proposed reactor design for Units 3 and 4. 

On March 9, 2010, STPNOC submitted a Department of the Army Permit application 

(STPNOC 2010c) to the U.S. Army Corps of Engineers (Corps) Galveston District for activities 

associated with constructing and operating STP Units 3 and 4. On March 25, 2010, the Corps 

published a public notice pursuant to Section 404 of the Federal Water Pollution Control Act 

(Clean Water Act) and Section 10 of the Rivers and Harbors Appropriation Act of 1899. The 

Corps is participating with the NRC in preparing this environmental impact statement (EIS) as a 

cooperating agency. 

Section 102 of the National Environmental Policy Act of 1969, as amended (NEPA) 

(42 USC 4321 et seq.), directs that an EIS is required for major Federal actions that significantly 

affect the quality of the human environment. Section 102(2)(C) of NEPA requires that an EIS 

include information about the following: 

• the environmental impacts of the proposed action; 

• any adverse environmental effects that cannot be avoided should the proposal be 

implemented; 

• alternatives to the proposed action; 

• the relationship between local short-term uses of the environment and the maintenance and 

enhancement of long-term productivity; and 

• any irreversible and irretrievable commitments of resources that would be involved if the 

proposed action is implemented. 
Conclusions and Recommendations 

NUREG-1937 10-2 February 2011 

The NRC has implemented NEPA in Title 10 of the Code of Federal Regulations (CFR) Part 51. 

In 10 CFR 51.20, the NRC requires preparation of an EIS for issuance of COLs. Subpart C of 

10 CFR Part 52 contains the NRC regulations related to COLs. 

The proposed actions related to the Units 3 and 4 application are (1) the NRC issuance of COLs 

for construction and operation of two new nuclear units at the STP site in Matagorda County, 

Texas; and (2) the Corps issuance of a permit pursuant to Section 404 of the Clean Water Act 

and Section 10 of the Rivers and Harbors Appropriation Act. The permit application to the 

Corps requests authorization to expand an existing barge slip on the Colorado River and to 

culvert and fill waters of the United States for the purpose of constructing a heavy haul road on 

the site. 

The environmental review described in this EIS was conducted by a team consisting of NRC 

staff, its contractor’s staff, and staff from the Corps. During the course of preparing this EIS, the 

review team reviewed the Environmental Report (ER) submitted by STPNOC (2010d) and 

supplemental documentation; consulted with Federal, State, Tribal, and local agencies; and 

followed the guidance set forth in NUREG-1555, Environmental Standard Review Plan (NRC 

2000) and Staff Memorandum Addressing Construction and Preconstruction, Greenhouse Gas 

Issues, General Conformity Determinations, Environmental Justice, Need for Power, Cumulative 

Impact Analysis, and Cultural/Historical Resources Analysis Issues in Environmental Impact 

Statements (NRC 2010). In addition, the NRC considered the public comments related to the 

environmental review received during the scoping process. The in-scope comments and 

responses are provided in Appendix D. The review team also considered public comments 

received on the draft EIS. Those comments and responses are provided in Appendix E of this 

final EIS. 

Included in this EIS are (1) the results of the review team’s analyses, which consider and weigh 

the environmental effects of the proposed actions; (2) mitigation measures for reducing or 

avoiding adverse effects; (3) the environmental impacts of alternatives to the proposed action; 

and (4) the NRC staff’s recommendation regarding the proposed action based on its 

environmental review. 

The COL application references a certified reactor design, as modified by STPNOC’s proposed 

amendment to the ABWR (STPNOC 2010b). This EIS accounts for STPNOC’s proposed 

amendment to the ABWR design certification. Where appropriate, this EIS adopts results of the 

environmental review conducted in support of the original design certification application and 

proposed amendment and incorporates those results by reference. 

As a cooperating agency, the Corps has participated in the environmental review and EIS 

preparation. The proposed action includes impacts on waters of the United States. For 

proposed actions requiring a Section 404 Clean Water Act permit for the discharge of dredged 

and/or fill material into waters of the United States, regulations promulgated by the U.S. 
 Conclusions and Recommendations 

February 2011 10-3 NUREG-1937 

Environmental Protection Agency (EPA) require the Corps to limit its authorization to the least 

environmentally damaging practicable alternative. The Corps will document its conclusion of 

the review process, including the requirement for compensatory mitigation, in accordance with 

33 CFR Part 332, Compensatory Mitigation for Losses of Aquatic Resources, in its permitdecision document. 

Environmental issues are evaluated using the three-level standard of significance – SMALL, 

MODERATE, or LARGE – developed by the NRC using guidelines from the Council on 

Environmental Quality (CEQ) (40 CFR 1508.27). Table B-1 of 10 CFR Part 51, Subpart A, 

Appendix B, provides the following definitions of the three significance levels: 

SMALL – Environmental effects are not detectable or are so minor that they will neither 

destabilize nor noticeably alter any important attribute of the resource. 

MODERATE – Environmental effects are sufficient to alter noticeably, but not to destabilize, 

important attributes of the resource. 

LARGE – Environmental effects are clearly noticeable and are sufficient to destabilize 

important attributes of the resource. 

Mitigation measures were considered for each environmental issue and are discussed in the 

appropriate sections. During its environmental review, the NRC and Corps review team 

considered planned activities and actions that STPNOC indicates it and others would likely take 

should STPNOC receive the COLs. In addition, STPNOC provided estimates of the 

environmental impacts resulting from the building and operation of two new nuclear units on the 

proposed site. 

10.1 Impacts of the Proposed Action 

In a final rule dated October 9, 2007 (72 FR 57416), the Commission limited the definition of 

“construction” to those activities that fall within its regulatory authority (10 CFR 51.4). Many of 

the activities required to build a nuclear power plant are not part of the NRC action to license the 

plant. Activities associated with building the plant that are not within the purview of the NRC 

action are grouped under the term “preconstruction.” Preconstruction activities include clearing 

and grading, excavating, erection of support buildings and transmission lines, and other 

associated activities. Because the “preconstruction” activities are not part of the NRC action, 

their impacts are not reviewed as a direct effect of the NRC action. Rather, the impacts of the 

preconstruction activities are considered in the context of cumulative impacts. Although the 

preconstruction activities are not part of the NRC action, they support or are requisite to the 

NRC action. In addition, certain preconstruction activities require permits from the Corps, as 

well as other Federal, State, and local agencies. 
Conclusions and Recommendations 

NUREG-1937 10-4 February 2011 

Chapter 4 describes the relative magnitude of impacts related to preconstruction and 

construction activities with a summary of impacts in Table 4-7. Impacts associated with 

operation of the proposed facilities are discussed in Chapter 5 and are summarized in 

Table 5-21. Chapter 6 describes the impacts associated with the fuel cycle, transportation, and 

decommissioning. Chapter 7 describes the impacts associated with preconstruction and 

construction activities and operation of Units 3 and 4 when considered along with the cumulative 

impacts of other past, present, and reasonably foreseeable future projects in the geographic 

region around the STP site. 

10.2 Unavoidable Adverse Environmental Impacts 

Section 102(2)(C)(ii) of NEPA requires that an EIS include information on any adverse 

environmental effects that cannot be avoided should the proposal be implemented. 

Unavoidable adverse environmental impacts are those potential impacts of the NRC action and 

the Corps action that cannot be avoided and for which no practical means of mitigation are 

available. 

10.2.1 Unavoidable Adverse Impacts During Construction and Preconstruction 

Chapter 4 discusses in detail the potential impacts from construction and preconstruction of the 

proposed Units 3 and 4 at the STP site and presents mitigation and controls intended to lessen 

the adverse impacts. Table 10-1 presents the adverse impacts associated with construction 

and preconstruction activities to each of the resource areas evaluated in this EIS, and the 

mitigation measures that would reduce the impacts. Those impacts remaining after mitigation is 

applied are identified in the table as the unavoidable adverse impacts. Unavoidable adverse 

impacts are the result of both construction and preconstruction activities, unless otherwise 

noted. The impact determinations in Table 10-1 are for the combined impacts of construction 

and preconstruction, but the impact determinations for NRC-regulated construction are the 

same for each resource area. 

Table 10-1. Unavoidable Adverse Environmental Impacts from Construction and 

Preconstruction Activities 

Resource Area Impacts Mitigation Measures Unavoidable Adverse Impacts

Land Use SMALL Comply with requirements of 

applicable Federal, State, and 

local permits. 

Approximately 300 ac committed on 

a long-term basis and 240 ac 

disturbed on a temporary basis. 

Water Use SMALL Comply with the requirements 

of Coastal Plains 

Groundwater Conservation 

District (CPGCD) permitting 

rules. 

New groundwater wells would be 

installed in the Deep Aquifer to 

supply water for building needs. 

Increased groundwater use from the 

Deep Aquifer because of the building 

and testing of Units 3 and 4. 
 Conclusions and Recommendations 

February 2011 10-5 NUREG-1937 

Table 10-1. (contd) 

Resource Area Impacts Mitigation Measures Unavoidable Adverse Impacts

Water Quality SMALL Implement best management 

practices (BMPs) and a sitespecific Stormwater Pollution 

Prevention Plan (SWPPP). 

Onsite and offsite water bodies 

would receive stormwater runoff 

during building phase. 

 Comply with Federal and 

State permits and 

implementation of BMPs. 

Dredging in the Colorado River near 

the Reservoir Makeup Pumping 

Facility (RMPF) and barge slip. 

 Compliance with CPGCD 

permitting rules and 

implementation of BMPs. 

Inadvertent spills (i.e., accidental, 

unintentional spills that seep into the 

Shallow Aquifer and are unable to be 

contained or remediated). 

Ecological 

(Terrestrial) 

SMALL Implement BMPs and Avian 

Protection Plans. 

Habitat loss and increased risk of 

collision and direct mortality; 

temporary wildlife displacement and 

avoidance due to noise and 

increased activities. 

 Implement BMPs and 

avoidance. 

No temporary or permanent losses of 

wetlands are expected. 

Ecological 

(Aquatic) 

SMALL Implement BMPs and a sitespecific SWPPP. Purchase 

stream credits from the Mill 

Creek Mitigation Bank. 

Habitat loss from dredging and barge 

slip expansion. Construction of 

heavy haul road has resulted in loss 

of relatively permanent waters. 

Socioeconomic 

Physical 

Impacts 

SMALL to 

MODERATE 

Alert local governmental 

agencies concerning needed 

road repairs. 

Minor temporary impacts during 

building phase. 

 Develop and implement a 

construction traffic 

management plan during 

building phase. 

Noticeable impacts to traffic in 

Matagorda County during building 

phase. 

Demography SMALL to 

MODERATE 

None. Noticeable demographic impacts in 

Matagorda County during building 

phase. 

Economic 

Impacts 

SMALL to 

MODERATE 

(beneficial) 

None. None. 

Community 

Services and 

Infrastructure 

SMALL TO 

MODERATE 

Add infrastructure and 

personnel as necessary. 

Some temporary shortages of 

facilities may occur during the 

building period 
Conclusions and Recommendations 

NUREG-1937 10-6 February 2011 

Table 10-1. (contd) 

Resource Area Impacts Mitigation Measures Unavoidable Adverse Impacts

 Maintain communication with 

local government and 

planning officials so that 

ample time is given to plan for 

the influx of population during 

the building phase. Add 

modular classrooms, 

infrastructure, and personnel 

as necessary, during building 

phase. 

Some temporary infrastructure 

shortages and crowding in housing 

and in education facilities during the 

building period. 

Environmental 

Justice 

SMALL None. None. 

Historic and 

Cultural 

SMALL Formal inadvertent discovery 

procedures are in place to 

minimize impacts to potential 

onsite historic and cultural 

resources. 

None. 

Air Quality SMALL Compliance with Federal, 

State, and local regulations 

governing construction 

activities and construction 

vehicle emissions. 

Implementation of a dust 

control program. 

Increased equipment, vehicular, and 

fugitive dust emissions but impacts 

would be temporary. 

Nonradiological 

Health 

SMALL Adherence to permits and 

authorizations issued by State 

and local agencies. 

Temporary public health impacts 

from exposure to fugitive dust and 

vehicular emissions, noise, and 

increased occupational injuries and 

traffic fatalities during the building 

phase. 

Radiological SMALL Doses to construction 

workers would be maintained 

below NRC public dose limits.

Small radiological dose to 

construction workers from operating 

units that would be less than NRC 

public dose limits. 

The primary unavoidable adverse environmental impacts during building activities would be 

related to land use and terrestrial habitat loss, as approximately 300 ac would be permanently 

disturbed and approximately 240 ac would be temporarily disturbed. All building activities for 

Units 3 and 4, including ground-disturbing activities, would occur within the existing STP site 

boundary. 
 Conclusions and Recommendations 

February 2011 10-7 NUREG-1937 

No surface water use is proposed during building activities. Several surface-water bodies 

including the Little Robbins Slough, the Main Cooling Reservoir (MCR), the existing Main 

Drainage Channel, and proposed site drainage channels that flow to the Colorado River and the 

West Branch of the Colorado River would be affected during building activities. Replacement 

and placing of new culverts on the site would also affect some onsite sloughs. BMPs would be 

employed to control runoff to onsite water bodies under a SWPPP. The impacts on surface 

water quality of onsite and offsite water bodies would be temporary. Dredging activities in the 

Colorado River near the RMPF and the barge slip may result in disturbance of sediments and 

increased turbidity. The increased turbidity would be localized and temporary. 

Groundwater aquifers that would potentially be affected include the Upper and Lower Shallow 

Aquifers into which the slurry wall, excavation, and fill would penetrate, and the Deep Aquifer in 

which one or more additional production wells would be installed. Dewatering systems 

employed during excavation within the powerblock area would depress the water table in the 

general vicinity; however, the impacts would be localized and temporary. 

Ecological impacts from building the proposed units would include loss of terrestrial and aquatic 

habitats. Terrestrial ecological impacts would include habitat loss during clearing and grading of 

the proposed site, risk of avian and bat collisions with construction equipment, and direct 

mortality of species from onsite preconstruction and construction activities. BMPs and 

avoidance would be used to minimize adverse impacts to wetlands. Aquatic ecological impacts 

would include habitat loss from activities in the Colorado River and onsite waterbodies. 

SWPPPs include BMPs to manage loss of aquatic habitat during construction and 

preconstruction activities. STPNOC has proposed compensation for unavoidable impacts to 

relatively permanent waters resulting from the construction of the heavy haul road by 

purchasing stream credits from the Mill Creek Mitigation Bank (STPNOC 2010e). 

Socioeconomic impacts of building the proposed units would include an increase in traffic from 

construction workers, and possible demand pressure on the local housing market and some 

other public services if workers concentrate in Matagorda County. No unusual resource 

dependencies on minority and low-income populations in the region were identified. 

Atmospheric and meteorological impacts include fugitive dust from land disturbing and building 

activities that can be mitigated by the dust-control plan. 

The review team did not identify any cultural resources that would be affected by building the 

proposed units. STPNOC has agreed to follow procedures if historic or cultural resources are 

discovered during ground-disturbing activities associated with building the proposed Units 3 

and 4. These procedures are detailed in STPNOC’s Addendum #5 to Procedures No. 

OPGP03-ZO-0025 Rev. 12 “Unanticipated Discovery of Cultural Resources” (STPNOC 2008). 
Conclusions and Recommendations 

NUREG-1937 10-8 February 2011 

Nonradiological health impacts to members of the public from construction, including public and 

occupational health, noise and transportation of materials, equipment and personal, would be 

minimal through controls and measures by STPNOC associated with compliance with Federal, 

State, and local regulations, permits and authorizations. 

Radiological doses to construction workers at Units 3 and 4 from the adjacent operating units 

are expected to be well below regulatory limits. 

10.2.2 Unavoidable Adverse Impacts During Operation 

Chapter 5 provides a detailed discussion of the potential impacts from operation of the proposed 

Units 3 and 4 at the STP site and presents mitigation and controls intended to lessen the 

adverse impacts. Table 10-2 presents the adverse impacts associated with operation of the two 

proposed units to each of the resource areas evaluated in this EIS and the mitigation measures 

that would reduce the impacts. Those impacts remaining after mitigation is applied are 

identified in the table as the unavoidable adverse impacts. 

Table 10-2. Unavoidable Adverse Environmental Impacts from Operation 

Resource Area Impact Mitigation Measures

Unavoidable Adverse 

Impacts

Land Use SMALL Adherence to local land 

management plans. 

Land would not be available 

for other use until after 

decommissioning of the entire 

STP site, including the 

proposed two new units. 

Water Use SMALL Compliance with STPNOC’s 

Texas Commission for Water 

Quality (TCEQ) water rights 

permit limits and STPNOC’s 

water delivery contract with 

Lower Colorado River 

Authority (LCRA). 

Increased surface water use 

from the Colorado River 

because of the addition of 

Units 3 and 4. 

 Compliance with CPGCD 

groundwater permit limits. 

Increased groundwater use 

from the Deep Aquifer 

because of addition of Units 3 

and 4. 
 Conclusions and Recommendations 

February 2011 10-9 NUREG-1937 

Table 10-2. (contd)

Resource Area Impact Mitigation Measures

Unavoidable Adverse 

Impacts

Water Quality SMALL Implement BMPs and 

Stormwater Management 

Plan. 

Increased sediment load in 

stormwater and potential to 

contaminate surface and 

groundwater through 

inadvertent spills. 

 Compliance with STPNOC’s 

Texas Pollutant Discharge 

Elimination System (TPDES) 

permit. 

Compliance with CPGCD 

permitting rules and 

implementation of BMPs. 

Increased frequency of 

discharge of MCR waters to 

the Colorado River. 

Inadvertent spills (i.e., 

accidental, unintentional 

spills that seep into the 

Shallow Aquifer and are 

unable to be contained or 

remediated). 

Ecological 

(Terrestrial) 

SMALL Implement BMPs to limit 

potential impacts from 

vegetation control, road 

maintenance, and other 

corridor activities. Follow 

Avian Protection Plan. 

Transmission line 

maintenance would prevent 

forest succession and 

maintain habitat 

fragmentation. New 

structures would represent 

an incremental increase in 

the risk of collision for birds 

and bats. Noise and 

activities during operation 

would cause wildlife to 

avoid certain areas. 

Ecological 

(Aquatic) 

SMALL RMPF already includes 

design features to mitigate 

adverse impacts. Use 

screens at circulating water 

intake structure. 

Cooling water withdrawal 

would result in 

impingement, entrainment, 

and entrapment of some 

Colorado River species. 

 Meet all applicable State and 

Federal regulatory 

requirements regarding the 

discharge of heat. 

MCR discharge thermal 

plume in the Colorado River 

may affect habitat, 

behavior, migration, 

abundance and distribution 

of some species.

 Meet all applicable State and 

Federal Clean Water Act and 

TPDES permit regulations 

and limitations. 

Nonradiological wastewater 

discharge (e.g., bio-fouling 

and other process control 

chemicals) would increase 

and this may affect aquatic 

species. 
Conclusions and Recommendations 

NUREG-1937 10-10 February 2011 

Table 10-2. (contd)

Resource Area Impact Mitigation Measures

Unavoidable Adverse 

Impacts

 MCR discharge system 

design includes features to 

minimize physical impacts. 

MCR discharge into 

Colorado River may cause 

physical scouring that would 

affect aquatic species and 

habitat in the area. 

 Implement BMPs for 

maintenance and operation 

activities (e.g., approved 

herbicide usage and 

SWPPP). 

Maintenance and operation 

activities (e.g., application 

of chemicals for vegetation 

management) along 

transmission corridor could 

harm aquatic species. 

Socioeconomic 

Physical SMALL Continue to implement 

strategies from the building 

period with consideration of 

smaller but more permanent 

impacts. 

Very minor levels of 

increased traffic; increased 

use of schools services, 

shortages of facilities and 

personnel for some public 

services in Matagorda 

County (but less than during 

the building period). 

Demography SMALL None. Matagorda County’s 

population would grow by 3 

to 4 percent over a few 

years. 

Economic Impacts SMALL to 

LARGE 

(beneficial) 

None. None. 

Community 

Services and 

Infrastructure 

SMALL None. Minor impact on traffic from 

additional workers. Impact 

would be minimal on 

housing demand and 

prices. 

Environmental 

Justice 

SMALL None. None. 

Historic and Cultural SMALL Formal inadvertent discovery 

procedures are in place to 

minimize impacts to potential 

onsite historic and cultural 

resources. 

None. 
 Conclusions and Recommendations 

February 2011 10-11 NUREG-1937 

Table 10-2. (contd)

Resource Area Impact Mitigation Measures

Unavoidable Adverse 

Impacts

Air Quality SMALL Compliance with Federal, 

State, and local air quality 

permits and regulations. 

Slight increase in certain 

criteria pollutants and CO2

due to plant auxiliary 

combustion equipment 

(e.g., diesel engines, 

combustion turbines); 

plumes and drift deposition 

from cooling towers; 

increase fogging from the 

MCR. 

Nonradiological 

Health 

SMALL State water quality 

monitoring for bacteria and 

compliance with TPDES 

permit for thermal 

discharges. 

MCR discharge thermal 

plume could encourage 

growth of etiological agents 

in Colorado River. 

 None. Noise from onsite systems 

(cooling towers,

transformers, loud 

speakers) would be <65 

decibels at 400 ft. 

 Conformance with Federal 

codes. 

Electrical shock from 

transmission lines. 

 Implementation of existing 

STP industrial safety 

program. 

Occupational injuries and 

illnesses. 

 Stagger arrival/departure 

times as well as outage 

schedule to minimize 

impacts to transportation 

routes. 

Accidents associated with 

transportation of operation 

and outage workers. 
Conclusions and Recommendations 

NUREG-1937 10-12 February 2011 

Table 10-2. (contd)

Resource Area Impact Mitigation Measures

Unavoidable Adverse 

Impacts

Radiological SMALL Doses to members of the 

public would be maintained 

below NRC and EPA 

standards; workers’ doses 

would be maintained below 

NRC limits and as low as is 

reasonably achievable 

(ALARA); and mitigative 

actions instituted for 

members of the public would 

also ensure doses to biota 

other than humans would be 

well below National Council 

on Radiation and 

Measurements (NCRP) and 

International Atomic Energy 

Agency (IAEA) guidelines. 

Small radiation doses to 

members of the public 

below NRC and EPA 

standards; ALARA doses to 

workers; and biota doses 

less than NCRP and IAEA 

guidelines. 

The unavoidable adverse impacts from operation for land use would be minimal and are 

associated with making land unavailable for other uses until after decommissioning of the two 

existing and two proposed units. 

Water-related impacts during operation would be mitigated through STPNOC’s adherence to 

State permits for water withdrawal and discharge. Remaining adverse impacts to hydrological 

water-use and water-quality impacts during operation would be minimal and limited to increased 

water use, potential increases in sedimentation to surface water bodies, potential surface and 

groundwater contamination from inadvertent spills. 

Unavoidable adverse impacts to terrestrial resources would include increased risks of bird and 

bat collisions with structures, wildlife avoidance due to noise, and minimal impacts of salt 

deposition on vegetation within 660 ft of the mechanical draft cooling towers. Assuming that 

BMPs are followed, terrestrial impacts during operation would be minor. Aquatic impacts would 

be minimal during operation because the design of the intake structure on the Colorado River 

would have minimal effects to aquatic organisms from impingement, entrainment, and 

entrapment. Aquatic impacts from MCR discharge into the Colorado River would have minimal 

effects to aquatic organisms; however, as discussed in Section 5.3.2, under certain flow 

conditions the thermal plume in combination with the water quality of the Colorado River could 

create conditions that would have noticeable effects but would not destabilize the aquatic 

community. 
 Conclusions and Recommendations 

February 2011 10-13 NUREG-1937 

Adverse socioeconomic impacts likely would be similar in character to those during the building 

phase but much smaller due to the smaller project-related population and the fact that much of 

the mitigation of housing and infrastructure shortages would have occurred in response to the 

larger impacts during the building period. Adverse socioeconomic impacts would primarily be 

increased traffic, some damage to roads, and an increase in the demand for housing and public 

services. Beneficial socioeconomic impacts would be increased employment opportunities and 

an increase in tax revenue to support the increased demand for services. 

The review team did not identify any cultural resources that would be affected by operation of 

the proposed units. STPNOC has agreed to follow procedures if historic or cultural resources 

are discovered during operation activities associated with the proposed Units 3 and 4. These 

procedures are detailed in STPNOC’s Addendum #5 to procedures No. OPGP03-ZO-0025 

Rev. 12 “Unanticipated Discovery of Cultural Resources” (STPNOC 2008). 

It is expected that air-quality impacts would be negligible and that pollutants emitted during 

operations would be insignificant. Nonradiological and radiological health impacts would be 

minimal. Nonradiological health impacts to members of the public from operation, including 

etiological agents, noise, electromagnetic fields, occupational health, and transportation of 

materials and personal, would be minimal through controls and measures by STPNOC 

associated with compliance to Federal and State regulations. 

Radiological doses to members of the public from operation of proposed Units 3 and 4 would be 

below NRC and EPA standards. Doses to workers from operation of proposed Units 3 and 4 

would also be below NRC limits and would be maintained ALARA. The radiation protection 

measures designed to maintain doses to members of the public below NRC and EPA standards 

would also ensure that doses to biota other than humans would be well below NCRP and IAEA 

guidelines. 

10.3 Relationship Between Short-Term Uses and Long-Term 

Productivity of the Human Environment 

Section 102(2)(C)(iv) of NEPA requires that an EIS include information on the relationship 

between local short-term uses of the environment and the maintenance and enhancement of 

long-term productivity. 

The local use of the human environment by the proposed project can be summarized in terms of 

the unavoidable adverse environmental impacts of construction and operation and the 

irreversible and irretrievable commitments of resources. With the exception of the consumption 

of depletable resources as a result of plant construction and operation, these uses may be 

classed as short term. The principal short-term benefit of the plant is represented by the 

production of electrical energy; and the economic productivity of the site, when used for this 
Conclusions and Recommendations 

NUREG-1937 10-14 February 2011 

purpose, would be extremely large compared to the productivity from agriculture or from other 

probable uses for the site. 

The maximum long-term impact to productivity would result when the plant is not immediately 

dismantled at the end of the period of plant operation, and consequently the land occupied by 

the plant structures would not be available for any other use. However, the enhancement of 

regional productivity resulting from the electrical energy produced by the plant is expected to 

result in a correspondingly large increase in regional long-term productivity that would not be 

equaled by any other long-term use of the site. In addition, most long-term impacts resulting 

from land-use preemption by plant structures can be eliminated by removing these structures or 

by converting them to other productive uses. Once the plants are shut down, they would be 

decommissioned according to NRC regulations. Once decommissioning is complete and the 

NRC license is terminated, the site would be available for other uses. 

The review team concludes that the negative aspects of plant construction and operation as 

they affect the human environment would be outweighed by the positive long-term 

enhancement of regional productivity through the generation of electrical energy. 

10.4 Irreversible and Irretrievable Commitments of 

Resources 

Section 102(2)(C)(v) of NEPA requires that an EIS include information on any irreversible and 

irretrievable commitments of resources that would occur if the proposed actions are 

implemented. The term “irreversible commitments of resources” refers to environmental 

resources that would be irreparably changed by the new units and that could not be restored at 

some later time to the resource’s state before the relevant activities. “Irretrievable commitments 

of resources” refers to materials that would be used for or consumed by the new units in such a 

way that they could not, by practical means, be recycled or restored for other uses. The 

resources discussed in this section are the environmental resources discussed in Chapters 4, 5, 

and 6. 

10.4.1 Irreversible Commitments of Resources 

Potential irreversible commitments of environmental resources resulting from Units 3 and 4, in 

addition to the materials used for the nuclear fuel, are described in the following subsections. 

10.4.1.1 Land Use 

The disposal of radioactive and nonradioactive wastes would require the long-term or 

irreversible commitment of land. The land used for Units 3 and 4 is not irreversibly committed 

because once Units 3 and 4 cease operations and the plant is decommissioned in accordance 
 Conclusions and Recommendations 

February 2011 10-15 NUREG-1937 

with NRC requirements, the land supporting the facilities could be returned to other industrial or 

nonindustrial uses. 

10.4.1.2 Water Use 

Approximately 21,600 gpm of cooling water from the MCR would be lost through consumptive 

use (i.e., evaporation) during operation. The UHS cooling towers, which are supplied by onsite 

groundwater wells, would additionally lose 566 gpm through evaporation. 

10.4.1.3 Aquatic and Terrestrial Biota 

Construction, preconstruction, and operation activities would cause temporary and long-term 

changes to both the aquatic and terrestrial biota at the plant site and facilities. These activities 

would change the abundance and distribution of local terrestrial flora and fauna on the STP site; 

however, enough suitable habitat exists elsewhere in the area that such changes would not 

result in adverse impacts on the regional populations despite localized permanent loss of habitat 

associated with the construction footprint for Units 3 and 4. Terrestrial habitats could be 

restored after decommissioning of the proposed reactors and thus no irretrievable loss of 

terrestrial habitats would be expected. STPNOC has indicated that no wetlands would be filled 

or affected, thus no irretrievable loss of wetland habitats would be expected to occur. In 

addition, no irretrievable loss of resources detectable at the population level would be expected 

as a result of operations. The review team expects that no irretrievable commitment of 

resources affecting terrestrial habitats or species would be expected to occur associated with 

upgrades to the Hillje transmission corridor. 

Construction, preconstruction, and operation activities would adversely affect the abundance 

and distribution of the aquatic community, including designated essential fish habitat (EFH), in 

the Colorado River in the vicinity of the RMPF, barge slip, and discharge structure. The review 

team expects that these activities would likely have more than minimal, but less than substantial 

adverse effect on EFH within the Colorado River by loss of forage and/or shelter habitat as well 

as early life stages of some species (see EFH assessment in Appendix F). The review team 

expects that no irretrievable commitment of resources affecting habitat or individual species is 

expected to occur associated with the new transmission corridors. STPNOC has proposed 

compensation for unavoidable impacts to relatively permanent waters resulting from the 

construction of the heavy haul road by purchasing stream credits from the Mill Creek Mitigation 

Bank (STPNOC 2010e). The aquatic habitat and aquatic populations would recover once Units 

3 and 4 cease operations and the plant is decommissioned in accordance with NRC 

requirements. 
Conclusions and Recommendations 

NUREG-1937 10-16 February 2011 

10.4.1.4 Socioeconomic Resources 

The review team expects that no irreversible socioeconomic commitments would be made to 

socioeconomic resources since they would be reallocated for other purposes once the plant is 

decommissioned. 

10.4.1.5 Air and Water 

Dust and other emissions such as vehicle exhaust would be released to the air during 

construction and preconstruction. During operations, vehicle exhaust emissions would continue 

and other air pollutants and chemicals including very low concentrations of radioactive gases 

and particulates would be released from the facility to the air and surface water. Because these 

releases would conform to applicable Federal and State regulations, their impact to the public 

health and the environment would be limited. The review team expects no irreversible 

commitment to air or water resources because all Unit 3 and 4 releases would be made in 

accordance with duly issued permits. 

10.4.2 Irretrievable Commitments of Resources 

A study by the U.S. Department of Energy (DOE 2004a) on new reactor construction estimated 

the following quantities of materials would be required for a single reactor: 12,239 yd3 of 

concrete, 3107 tons of rebar, 13,000,000 ft of cable, and 275,000 ft of piping. Therefore, about 

twice these amounts would be needed for proposed Units 3 and 4 at STP, and considerably 

more would be required for all the other site structures. 

The review team expects that the use of construction materials in the quantities associated with 

those expected for Units 3 and 4 at the STP site, while irretrievable, would be of small 

consequence with respect to the availability of such resources. 

The main resource that would be irretrievably committed during operation of the new nuclear 

units would be uranium. The availability of uranium ore and existing stockpiles of highly 

enriched uranium in the United States and Russia that could be processed into fuel is sufficient 

(OECD NEA and IAEA 2008), so that the irreversible and irretrievable commitment would be 

negligible. 

10.5 Alternatives to the Proposed Action 

Alternatives to the proposed actions are discussed in Chapter 9. Alternatives considered are 

the no-action alternative, energy production alternatives, system design alternatives, and 

alternative sites. For the purposes of the Corps’ evaluation, onsite alternatives are also 

addressed in Section 9.5. 
 Conclusions and Recommendations 

February 2011 10-17 NUREG-1937 

The NRC no-action alternative, described in Section 9.1, refers to a scenario in which the NRC 

would deny the STPNOC’s request for the COLs. Upon such a denial by the NRC, the 

construction and operation of two new nuclear units at the STP site in accordance with 

10 CFR Part 52 would not occur and the predicted environmental impacts associated with the 

project would not occur. If no other power plant were built or electrical power supply strategy 

implemented to take its place, the electrical capacity to be provided by the project would not 

become available, and the benefits (electricity generation) associated with the proposed action 

would not occur and the need for power would not be met. 

Alternative energy sources are described in Section 9.2. Alternatives that would not require 

additional generating capacity are described in Section 9.2.1. Detailed analyses of coal- and 

natural-gas-fired alternatives are provided in Section 9.2.2. Other energy sources are 

discussed in Section 9.2.3. A combination of energy alternatives is discussed in Section 9.2.4. 

Based on its analysis presented in Section 9.2, the NRC staff concluded that none of the 

alternative energy options were both (1) consistent with STPNOC’s objective of building 

baseload generation units to provide about 2700 MW(e), and (2) environmentally preferable to 

the proposed action. 

Alternative sites are discussed in Section 9.3. The cumulative impacts of building and operating 

the proposed facilities at the alternative sites are compared to the impacts at the proposed STP 

site in Section 9.3.5. Table 9-20 contains the review team’s characterization of cumulative 

impacts at the proposed and alternative sites. Based on this review, the NRC staff concludes 

that while there are differences in cumulative impacts at the proposed and alternative sites, 

none of the alternative sites would be environmentally preferable or obviously superior to the 

proposed STP site. The NRC’s determination is independent of the Corps’ determination of a 

Least Environmentally Damaging Practicable Alternative pursuant to Clean Water Act Section 

404(b)(1) guidelines. The Corps will conclude its analysis of both offsite and onsite alternatives 

in its Record of Decisions. 

Alternative heat dissipation and circulating water system designs are discussed in Section 9.4. 

The NRC staff concluded that none of the alternatives considered would be environmentally 

preferable to the proposed system designs.

10.6 Benefit-Cost Balance 

NEPA requires that all agencies of the Federal Government prepare detailed environmental 

statements on proposed major Federal actions that can significantly affect the quality of the 

human environment. A principal objective of NEPA is to require each Federal agency to 

consider, in its decision making process, the environmental impacts of each proposed major 

action and the available alternative actions. In particular, Section 102 of NEPA requires all 

Federal agencies to the fullest extent possible: 
Conclusions and Recommendations 

NUREG-1937 10-18 February 2011 

“(B) identify and develop methods and procedures, in consultation with the 

Council on Environmental Quality established by title II of this Act, which will 

insure that presently unquantified environmental amenities and values may be 

given appropriate consideration in decisionmaking along with economic and 

technical considerations.” (42 USC 4321) 

However, neither NEPA nor CEQ requires the costs and benefits of a proposed action be 

quantified in dollars or any other common metric. 

The intent of this section is not to identify and quantify all of the potential societal benefits of the 

proposed actions and compare these to the potential costs of the proposed actions. Instead, 

this section will focus on only those benefits and costs of such magnitude or importance that 

their inclusion in this analysis can inform the decision-making process. This section compiles 

and compares the pertinent analytical conclusions reached in earlier chapters of this EIS. It 

gathers all of the expected impacts from building and operations of the proposed Units 3 and 4 

and aggregates them into two final categories: the expected costs and the expected benefits. 

The benefit-cost balancing for the NRC action will be based on a balancing of the benefits and 

costs of construction and operation. 

Although the analysis in this section is conceptually similar to a purely economic benefit-cost 

analysis, which determines the net present dollar value of a given project, the intent of this 

section is to identify all potential societal benefits of the proposed actions and compare these to 

the potential internal (i.e., private) and external (i.e., societal) costs of the proposed actions. 

The purpose is to generally inform the COL process by gathering and reviewing information that 

demonstrates the likelihood that the benefits of the proposed actions outweigh the aggregate 

costs. 

General issues related to STPNOC’s financial viability and those of its parent organizations are 

outside NRC’s mission and authority and, thus, would not be considered in this EIS. Issues 

related to the financial qualifications of STPNOC will be addressed in the NRC staff’s safety 

evaluation report. It is not possible to quantify and assign a value to all benefits and costs 

associated with the proposed action. This analysis, however, attempts to identify, quantify, and 

provide monetary values for benefits and costs when reasonable estimates are available. 

Section 10.6.1 discusses the benefits associated with the proposed action. Section 10.6.2 

discusses the costs associated with the proposed action. A summary of benefits is shown in 

Table 10-3. Section 10.6.3 provides a summary of the impact assessments, bringing previous 

sections together to establish a general impression of the relative magnitude of the proposed 

actions’ costs and benefits. 
 Conclusions and Recommendations 

February 2011 10-19 NUREG-1937 

Table 10-3. Summary of Benefits of the Proposed Action 

Benefit 

Category Description

Monetized Value or Impact 

Assessment

Benefits

Electricity 

generated 

20,000,000 to 22,000,000 MWh (Megawatt hour) per year for 

the 40-year life of the plant (assuming capacity factors in the 

range of 85-93 percent). 

Generating 

capacity 

2700 MW (two units at 1350 MW each). 

Fuel diversity 

and energy 

security 

Nuclear option provides diversity to coal- and natural-gas-fired 

baseload generation. Reduces exposure to supply and price 

risk associated with reliance on any single fuel source. 

Tax revenues Tax payments and service fees in In-lieu-of-taxes increase as 

STPNOC’s investment in building grows and as Units 3 and 4 

start generating electricity (see Sections 4.4.3.2 and 5.4.3.2). 

Franchise tax amount shown is based on STPNOC’s estimate 

of gross margin at 100 percent taxability. Under the proposed 

settlement between NINA and CPS (STPNOCd), both units 

are projected to be about 8 percent owned by non-taxable 

entities. Property taxes based on STPNOC’s estimate of 

capital cost and a range of 44 percent to 100 percent 

taxability. Capital cost may be higher, as described in Section 

10.6.2.1. 

Operations, between $4.7 

and $5.4 million (2015) and 

$8.6-$10.0 million per year 

(later years) in franchise 

taxes. $9.5 - $21.5 million 

per year in property taxes 

Local economy Increased jobs would benefit the area economically and 

increase the economic diversity of region (see 

Sections 4.4.3.1 and 5.4.3.1) 

1620 total regional 

employment; $73 million per 

year regional income 

Price Volatility Would dampen potential for fuel price volatility. 

Electrical 

Reliability 

Provides additional generating capacity and enhances 

electricity supply reliability and grid stability. 

10.6.1 Benefits

The most apparent benefit from a power plant is that it generates power and provides 

thousands of residential, commercial, and industrial consumers with electricity. Maintaining an 

adequate supply of electricity in any given region has social and economic importance because 

adequate electricity is the foundation for economic stability and growth and fundamental to 

maintaining our current standard of living. Because the focus of this EIS is on the proposed 

expansion of the STP site generating capacity, this section focuses primarily on the relative 

benefits of the STP option rather than the broader, more generic benefits of electricity supply. 
Conclusions and Recommendations 

NUREG-1937 10-20 February 2011 

10.6.1.1 Societal Benefits 

For the production of electricity to be beneficial to a society, there must be a corresponding 

demand, or “need for power,” in the region. Chapter 8 defines and discusses the need for 

power in more detail. From a societal perspective, nuclear power offers two primary benefits 

relative to most other generating systems: availability, long-term price stability, and energy 

security, and fuel diversity. These benefits are described in this subsection. 

Long-term Price Stability 

Because of its relatively low and stable fuel costs, nuclear energy is a dependable generator of 

electricity that can provide electricity to the consumer at relatively stable prices over a long 

period of time. Unlike some other energy sources, nuclear energy is generally not subject to 

unreliable weather or climate conditions, unpredictable cost fluctuations, and is less dependent 

on foreign suppliers than other energy sources. Nuclear power plants are generally not subject 

to fuel price volatility like natural gas and oil power plants. In addition, uranium fuel constitutes 

only 3 percent to 5 percent of the cost of a kilowatt-hour of nuclear-generated electricity. 

Doubling the price of uranium increases the cost of electricity by about 7 percent; while doubling 

the price of gas would add about 70 percent to the price of electricity, and doubling the cost of 

coal would add about 36 percent to the price of electricity (WNA 2010). 

Energy Security and Fuel Diversity

Currently, almost 70 percent of the electricity generated in the United States is generated with 

fossil-based technologies; thus, non-fossil-based generation, such as nuclear generation, is 

essential to maintaining diversity in the aggregate power-generation fuel mix (DOE/EIA 2010a). 

Nuclear power contributes to the diverse U.S. energy mix, hedging the risk of shortages and 

price fluctuations for any one power-generation system and reducing the nation’s dependence 

on imported fossil fuels. 

A diverse fuel mix helps to protect consumers from contingencies such as fuel shortages or 

disruptions, price fluctuations, and changes in regulatory practices. ERCOT’s 2009 fuel mix for 

annual generation was made up of approximately 42 percent natural gas, 37 percent coal, 

14 percent nuclear, and 7 percent hydroelectric and renewables (ERCOT 2010a). Summer 

capacity is more concentrated in natural-gas fired plants due to the need to address summer 

peak. Summer capacity percentages are natural gas, 66 percent; coal, 25 percent; nuclear, 

7 percent; and hydroelectric and renewables, about 3 percent. Efficiency programs and loads 

serving as reserves meet about 2-3 percent of summer peak demand (ERCOT 2010b). The 

effective load–carrying capacity of wind generation is rated by ERCOT at 8.7 percent of 

nameplate, or about 793 MW total at the beginning of 2010 (ERCOT 2010b). ERCOT is 

planning a capacity mix that provides the region with a hedge against the risks of future 

shortages and price fluctuations. The building of STP Units 3 and 4 fits with ERCOT’s strategy 

to continue generating power with a diverse fuel mix. 
 Conclusions and Recommendations 

February 2011 10-21 NUREG-1937 

10.6.1.2 Regional Benefits 

Regional benefits of the proposed construction and operation of Units 3 and 4 include enhanced 

tax revenues, regional productivity, and community impacts. 

Tax Revenue Benefits 

NINA Texas 3 LLC and NINA Texas 4 LLC would make tax payments and in-lieu-of tax 

payments to the State of Texas, Matagorda County, Palacios School District, and to other 

special taxing districts within Matagorda County. Tax payments on existing units are shown in 

Section 2.5.2.2, and taxes for the proposed Units 3 and 4 are identified in Sections 4.4.3.2 and 

5.4.3.2 

As the owners of Units 3 and 4 invest in building the power plant, the growing book value of the 

plant can increase the proportion of STPNOC’s property tax payments that the local taxing 

districts receive. This is on a construction work in progress basis. As power property is 

amortized, the proportion of tax equivalent payments may decline. The amount of property tax 

payments received by Matagorda County, some special service districts and the Palacios 

Independent School District (some of which it would share with other districts statewide) would 

significantly increase with the construction and operation of STP Units 3 and 4 (see Sections 

4.4.3.2 and 5.4.3.2). These impacts are discussed in Sections 4.4 and 5.4 of this document. 

In addition to in-lieu-of-tax payments by STPNOC, a variety of taxes would be paid on the 

wages, earnings, and expenditures that result from local purchases of materials and services for 

the construction of proposed Units 3 and 4. These various taxes are also described in Sections 

4.4 and 5.4 of this document. 

Regional Productivity and Community Impacts 

The new units would require a peak building workforce of as many as 6683 people (5950 

construction and 733 operations) and a net increase in the STP long-term operating workforce 

of 656 people. The increase in local economic activity would stimulate the creation of 2892 

additional indirect jobs during construction and 964 additional indirect jobs during long-term 

operations within the 50-mi region of STP influence (Sections 4.5 and 5.5). There would be a 

total of 10,308 new jobs in the region (6600 of them going to in-migrants and residents) at the 

peak of construction and a total of approximately 1620 new jobs within the region that would be 

maintained throughout the operating life of the plant. Roughly 86 percent would be in the four 

nearest counties (Matagorda, Brazoria, Calhoun, and Jackson). The employment and earnings 

multiplier effects from the increased spending by the direct and indirect workforce created as a 

result of two new units would increase the economic activity in the region, most noticeably in 

Matagorda County (STPNOC 2010d). Sections 4.5.3.1 and 5.5.3.1 provide additional 
Conclusions and Recommendations 

NUREG-1937 10-22 February 2011 

information on the economic impacts of constructing and operating proposed Units 3 and 4 on 

the STP site. 

The NRC staff’s interviews in communities surrounding the STP site revealed high perceived 

benefit to having the jobs, income, and people associated with the nuclear plant in their area 

(Scott and Niemeyer 2008). 

10.6.2 Costs

Internal costs to the owners of Units 3 and 4 as well as external costs to the surrounding region 

and environment would be incurred during the construction, preconstruction, and operation of 

two new units at the STP site. A summary of the costs is shown in Table 10-4. Internal costs 

include all of the costs included in a total capital cost assessment—the direct and indirect cost 

to physically build the power plant (capital costs), plus the annual costs of operation and 

maintenance, fuel costs, waste disposal, and decommissioning costs. In accordance with the 

NRC staff’s guidance in NUREG-1555 (NRC 2000), internal costs of the proposed project are 

presented in monetary terms. External costs include all costs imposed on the environment and 

region surrounding the plant that are not internalized by the company and may include such 

things as a loss of regional productivity, environmental degradation, or loss of wildlife habitat. 

The external costs listed below in Table 10-4 summarize environmental impacts to resources 

that could result from preconstruction, construction, and operation of the proposed Units 3 

and 4. Because Table 10-4 includes costs from preconstruction activities as well as NRCauthorized construction and operation, the costs presented for an individual resource may be 

greater than the costs solely for the NRC-authorized portion of the project. 

Table 10-4. Summary of Costs of Preconstruction, Construction, and Operation 

Cost Category Description

Impact 

Assessment(a)

Internal Costs(b)

Construction cost $6.2-$14.9 billion for the two STP units (overnight capital cost 

– 2008$)(c)

Operating cost 

Fuel cost 

3.8–10.9 cents per kWh (levelized cost of electricity – 2008$) 

Fuel cost is about 0.45 cents per kWh(d)

Spent fuel 

management(e)

Approximately 0.1 cents per kWh 

Decommissioning(f) Approximately 0.1 to 0.2 cents per kWh 
 Conclusions and Recommendations 

February 2011 10-23 NUREG-1937 

Table 10-4. (contd) 

Cost Category Description

Impact 

Assessment(a)

Material and 

resources(g)

480,000 yds3

 concrete (2 units) 

26,000 tons structural steel 

18 million linear ft of cable 

110,000 linear ft of large bore piping having diameter >2.5 in. 

34,000 metric tons of uranium 

Land use 90 ac are occupied on a long-term basis by the two new 

nuclear reactors and associated infrastructure. Rights-of-way 

maintained for transmission lines (see Sections 4.1 and 5.1). 

Total annual land requirements for fuel cycle support 

committed would be 21 permanently committed ac and 160 

temporarily committed ac per unit (STPNOC 2010d).

External Costs 

Land use No new land for transmission line rights-of-way would be 

taken out of other productive or beneficial use (see 

Sections 4.1 and 5.1). 

SMALL 

Water use Small local dewatering of shallow aquifer during construction. 

During operations, groundwater removal ranging from 

975 gpm (normal 2-unit operations) to 3434 gpm (maximum). 

Surface water withdrawal from Colorado River to replace 

water losses from the MCR would be 22,799 gpm (normal 

2-unit operations) to 47,489 gpm (maximum) 

(STPNOC 2010d, Table 3.3-1). Water use by inmigrating 

population of 112 gpm (based on Section 5.4). 

SMALL 

Air quality impacts Negligible impacts associated with sulfur dioxide, nitrogen 

oxide, carbon monoxide, carbon dioxide, and particulate 

emissions (Sections 4.7 and 5.7). 

SMALL 

Ecological impacts Terrestrial habitat loss (approximately 300 ac). STPNOC’s 

adherence to the TPDES permit would likely result in 

balanced aquatic populations. No threatened or endangered 

terrestrial or aquatic species likely to be adversely affected 

(see Sections 4.3 and 5.3). EFH for some species would be 

adversely affected (more than minimal but less than 

substantial). 

SMALL 
Conclusions and Recommendations 

NUREG-1937 10-24 February 2011 

Table 10-4. (contd) 

Cost Category Description

Impact 

Assessment(a)

Physical Impacts Traffic noise impacts limited primarily to boundaries of the site 

and immediate neighborhood. Temporary stress on road/local 

road network because of congestion during building and 

potential degradation from building and operation activities 

(see Sections 4.4.1 and 5.4.1). 

SMALL 

 Because a two-unit operating plant already exists onsite, there 

would be very little marginal impact on aesthetic and 

recreation from additional reactors (see Sections 4.4.1.4, 

4.5.3.4, 5.4.1.4, and 5.4.3.4). 

Community 

Services and 

Infrastructure 

Potential short-term strain on some community services and 

short-term strain on housing in Matagorda County during early 

stages of 7-year construction period (see Sections 4.4.4.6 and 

5.4.4.6). 

SMALL to 

MODERATE 

during 

construction, 

SMALL during 

operation 

(SMALL 

overall) 

Health Impacts 

(Nonradiological 

and Radiological) 

Minor estimated temperature increases would not significantly 

increase the abundance of thermophilic microorganisms. 

Radiological doses and nonradiological health hazards to the 

public and occupational workers would be monitored and 

controlled in accordance with regulatory limits (see Sections 

4.8, 4.9, 5.8, and 5.9). 

SMALL 

(a) Impact assessments are listed for all impacts evaluated in detail as part of this EIS. The details on impact assessments are 

found in the indicated sections of this EIS. 

(b) Internal costs are those incurred by STPNOC to implement proposed building and operation of Units 3 and 4. Note that no 

impact assessments are provided for these private financial impacts. 

(c) $6.2 billion is based on $2000/kW(e) in 2003$ used in STPNOC 2010d, escalated to 2008$. $14.9 billion is based on 

$5339/kW(e) in 2010$, estimated in DOE/EIA 2010b, escalated to 2008$ (2008 prices were higher than in 2010). 

(d) Review team calculation of price per kWh based on MIT (2009). 

(e) U.S. spent fuel program is funded by a 0.1 cent/kWh levy. 

(f) USA experience (WNA 2010). 

(g) From STPNOC 2010d and based on referenced plant design, which could change if the plant design is modified. 
Conclusions and Recommendations 

February 2011 10-25 NUREG-1937 

10.6.2.1 Internal Costs 

The most substantial monetary cost associated with nuclear energy is the cost of capital 

construction. Nuclear power plants have relatively high capital costs for building the plant but 

low fuel costs relative to alternative power-generation systems. The real prices of key heavy 

construction commodities, such as cement, steel, and copper, have increased substantially in 

recent years, which would have a significant impact on nuclear plant capital costs (although it 

should be noted that these price increases would increase construction costs for non-nuclear 

power plants as well).(a) Because of the large capital costs for nuclear power, and the relatively 

long construction period before revenue is returned, servicing the capital costs of a nuclear 

power plant is a key factor in determining the economic competitiveness of nuclear energy. 

Construction delays can add significantly to the cost of a plant. Because a power plant does not 

yield profits during construction, longer construction times mean a longer time before any costs 

can be offset by revenues. Furthermore the longer it takes to build the plant, the higher would 

be the interest expenses on borrowed construction funds. In general, because no new nuclear 

plants have been built in the United States in many years, there is a great deal of uncertainty 

about the true costs of a new unit, which can affect the cost of capital, and thereby affect the 

cost of the proposed project. 

Construction Costs 

In evaluating monetary costs related to constructing proposed Units 3 and 4, the review team 

reviewed recent published literature, vendor information, internally generated financial 

information, and internally generated, site-specific information. The review team also compared 

recent cost estimates with STPNOC’s. The cost estimates reviewed were not based on nuclear 

plant construction experience in the United States, which is more than 20 years old, but rather 

on more recent studies and more recent plant construction costs overseas. 

Capital costs are costs incurred during construction, including preconstruction, when the actual 

outlays for equipment and construction and engineering are made. “Overnight capital costs” 

include engineering, procurement, and construction costs; however, it is presumed that the plant 

is constructed overnight; thus, interest is not included. STPNOC based its estimates of 

overnight capital costs for construction and preconstruction on analysis of four comprehensive 

studies of nuclear plant costs (University of Chicago 2004; MIT 2003; DOE 2004b; NEA IEA and 

OECD 2005), in which estimates ranged from $1100 per kW to $2500 per kW (in 2002 dollars). 

STPNOC estimates that the top end of the overnight cost range increased to around 

 

(a) Although in real terms, the construction costs for large projects remained relatively flat from 1998 to 2002, 

various construction cost indices from such sources as the Electric Power Research Institute and McGraw Hill 

estimate real cost escalation for large power plant construction projects to be approximately 4 percent per year 

since 2002 (through 2007). This is based on actual field data as well as data on commodity costs, labor cost 

information, and other equipment (USDI/Reclamation 2008). 
Conclusions and Recommendations 

NUREG-1937 10-26 February 2011 

$2000 per kW in 2003 dollars (equivalent to about $2200 per KW in 2008 dollars). On this 

basis, STPNOC estimates an overnight capital cost for the two STP units of $5.4 billion in 2003 

dollars ($6.2 billion in 2008 dollars) (STPNOC 2010d). In addition to the studies STPNOC used, 

the review team also considered four other more recent estimates: two estimates of 

construction costs from other applicants, a 2009 update to the 2003 MIT study on the cost of 

nuclear power (MIT 2009), and an update of overnight capital costs by the Energy Information 

Administration (DOE/EIA 2010b). 

• Tennessee Valley Authority estimated its per kW cost of construction for two new proposed 

AP1000 units at its Bellefonte site in Alabama between $2850 and $3200 per kW (TVA 

2008), which if applied to proposed Units 3 and 4 at STP (installed capacity of 2700 MWe), 

would yield an overnight capital cost of $7.7 to $8.7 billion. 

• Southern Nuclear Operating Company estimated the overnight cost of construction for two 

AP1000 units at its Vogtle site in Georgia between $3200 and $3500 kW (Southern 2008), 

which if applied to proposed Units 3 and 4 at STP would yield an overnight capital cost of 

$8.7 billion to $9.5 billion. 

• The MIT Update (MIT 2009) estimated the overnight construction cost at $4000 per kW in 

2007$ (about $4100 per kW in 2008$) or about $11.1 billion for 2700 MWe in 2008$. 

• The DOE/EIA (DOE/EIA 2010b) estimated the overnight construction cost at $5339 per kW 

in 2010$ (about $5510 per kW in 2008$, when non-residential fixed investment was 3.2 

percent more costly than in 2010) or about $14.9 billion for 2700 MWe in 2008$. 

Operation Costs 

Operation costs are frequently expressed as levelized cost of electricity, which is the lowest 

price per kilowatt-hour of producing electricity that covers operating costs, annualized capital 

costs, and a reasonable profit. For nuclear power plants, overnight capital costs typically 

account for a third of the levelized cost, and interest costs on the overnight costs account for 

another 25 percent (STPNOC 2010d). STPNOC estimated that the levelized cost for Units 3 

and 4 would be in the range of $36 to $65 per MWh (3.6 to 6.5 cents per kWh), which is the 

range estimated by the four earlier studies mentioned above (STPNOC 2010d; University of 

Chicago 2004; MIT 2003; DOE 2004b; NEA IEA and OECD 2005). In addition, the review team 

examined the update to the MIT study (MIT 2009) which re-evaluated the overnight levelized 

cost of electricity at 8.4 cents per kWh (2007$) No levelized cost was available for the 2010 

DOE/EIA estimate, but by adjusting DOE’s 2010 overnight capital costs to 2007$ and entering 

them into the MIT model used for the 2009 update, the review team obtained an upper bound 

estimate of 10.6 cents per kWh for levelized cost of electricity in 2007$. In 2008$, this yields an 

overall range of 3.8 to 10.9 cents per kWh, which the review team determined was reasonable 

for this analysis. Factors affecting the range include choices for discount rate, construction 

duration, plant life span, capacity factor, cost of debt and equity, and split between debt and 
 Conclusions and Recommendations 

February 2011 10-27 NUREG-1937 

equity financing, depreciation time, tax rates, and premium for uncertainty. Estimates include 

decommissioning but, because of the effect of discounting a cost that would occur as much as 

40 years or more in the future, decommissioning costs have relatively little effect on the 

levelized cost. 

Fuel Costs 

STPNOC calculated nuclear fuel cost and decommissioning cost separately using information 

from a study published jointly by the University of Chicago (2004). In the report, the University 

of Chicago estimated the average fuel cost for a nuclear generating plant to be $4.35 per MWh, 

or 0.4 cents per kWh. Based on the recent World Nuclear Association’s study (WNA 2010), the 

review team estimated nuclear fuel costs to be $0.449 cents per kWh (WNA 2010). 

Waste Disposal 

The back-end costs of nuclear power contribute a very small share of total cost because of both 

the long lifetime of a nuclear reactor and the fact that provisions for waste-related costs can be 

accumulated over that time. Spent fuel management costs are estimated to be 0.1 cents per 

kWh (WNA 2010; DOE 2008). It should be recognized, however, that radioactive nuclear waste 

poses unique disposal challenges for long-term management. While spent fuel and radioactive 

nuclear waste are being stored successfully in on-site facilities, the United States has yet to 

implement final disposition of spent fuel or high-level radioactive waste streams created at 

various stages of the nuclear fuel cycle. 

Decommissioning 

NRC has requirements for licensees at 10 CFR 50.75 to provide reasonable assurance that 

funds would be available for the decommissioning process. Because of the effect of discounting 

a cost that would occur as much as 40 years in the future, decommissioning costs have 

relatively little effect on the levelized cost of electricity generated by a nuclear power plant. 

Decommissioning costs are about 9 to 15 percent of the initial capital cost of a nuclear power 

plant. However, when discounted, they contribute only a few percent to the investment cost and 

even less to generation cost. In the United States, they account for 0.1 to 0.2 cents per kWh 

(WNA 2010). 

10.6.2.2 External Costs 

External costs are social and/or environmental effects that would be caused by the construction 

of and generation of power by two new reactors at the STP site that are not compensated or 

mitigated through STPNOC’s financial and decision making processes. This EIS includes the 

review team’s analysis that considers and weighs the environmental impacts of building and 

operating new nuclear units at the STP site or at alternative sites and mitigation measures 
Conclusions and Recommendations 

NUREG-1937 10-28 February 2011 

available for reducing or avoiding these adverse impacts. It also includes the NRC staff’s 

recommendation to the Commission regarding the proposed action. 

Environmental and Social Costs 

Chapter 4 describes the impacts of building the proposed Units 3 and 4 on the environment with 

respect to the land, water, ecology, socioeconomics, radiation exposure to construction workers, 

and measures and controls to limit adverse impacts during building of the proposed new units at 

the STP site. Chapter 5 examines environmental issues associated with operation of the 

proposed new nuclear Units 3 and 4 for an initial 40-year period. Potential operational impacts 

on land use, air quality, water, terrestrial and aquatic ecosystems, socioeconomics, historic and 

cultural resources, environmental justice, nonradiological and radiological health effects, 

postulated accidents, and applicable measures and controls that would limit the adverse 

impacts of station operation during the 40-year operating period are considered. In accordance 

with 10 CFR Part 51, the review team analyzed all impacts identified in Chapters 4 and 5, and 

assigned a significance level of potential impacts (i.e., SMALL, MODERATE, or LARGE) to 

each category. 

Chapter 6 addresses the environmental impacts from (1) the uranium fuel cycle and solid waste 

management, (2) the transportation of radioactive material, and (3) the decommissioning of 

nuclear units at the STP site. Chapter 9 includes the review team's review of alternative sites 

and alternative power generation systems. 

Unlike generation of electricity from coal and natural gas, normal operation of a nuclear power 

plant does not result in significant emissions of criteria pollutants (e.g., oxides of nitrogen or 

sulfur dioxide), methyl mercury, or greenhouse gases associated with global warming and 

climate change. Whereas combustion-based power plants are responsible for at least 70 

percent of the sulfur dioxide, at least 21 percent of nitrogen oxides, and 51 percent of the 

mercury emissions from industrial sources in the United States (EPA 2009), and 40 percent of 

the carbon dioxide (DOE/EIA 2008). Eighty-two percent of the electric power industry’s 

emissions are from coal-fired plants (DOE/EIA 2008). Chapter 9 analyzes coal- and naturalgas-fired alternatives to the building and operation of proposed STP Units 3 and 4. Air 

emissions from these alternatives and nuclear power are summarized in Chapters 4, 5 and 9. 

Table 10-4 summarizes the external costs (i.e., environmental impacts) associated with the 

preconstruction, construction, and operation of the proposed STP Units 3 and 4. The review 

team determined that impacts to land use, air quality, aquatic and terrestrial ecology, aesthetics 

and recreation, cultural resources, and radiological and nonradiological health would all be 

SMALL. Because the overall impact to these resources from the proposed project in its entirety 

(40 plus years) would be SMALL, the NRC-authorized portion of the project (i.e., construction as 

defined in 10 CFR 51.4, and operation of the proposed new units) accordingly would also be 

SMALL. 
 Conclusions and Recommendations 

February 2011 10-29 NUREG-1937 

The review team concluded that impacts on public services (specifically housing, education, 

transportation, and some community services) associated with preconstruction and construction 

activities would be MODERATE. The impact from NRC-authorized construction activities would 

be MODERATE in Matagorda County. The operation of the units would result in SMALL 

impacts on public services. 

10.6.3 Summary of Benefits and Costs

The internal costs to construct additional units appear to be substantial; however, STPNOC’s 

decision to pursue this expansion implies that it has concluded that the internal benefits of the 

proposed facility (production of 20,000,000 to 22,000,000 MWh per year for the 40-year life of 

the plant and 2700 MW of baseload capacity) outweigh the internal costs. Although no specific 

monetary values could reasonably be assigned to the identified societal benefits, it would 

appear that the potential societal benefits of the proposed Units 3 and 4, including the primary 

benefit of the generated power and baseload capacity, are substantial. In comparison, the 

external socio-environmental costs imposed on the region appear to be relatively small. 

Table 10-3 includes a summary of identified benefits of the proposed activities at the STP site 

for Units 3 and 4, while Table 10-4 contains a summary of both internal and external costs. The 

tables include a reference to other sections of this EIS where more detailed analyses and 

impact assessments are available for specific topics. These assessments are included in the 

table. 

On the basis of the assessments summarized in this EIS, building and operating the proposed 

Units 3 and 4, with mitigation measures identified by the review team, would have accrued 

benefits that most likely would outweigh the economic, environmental, and social costs. For the 

NRC-proposed action (NRC-authorized construction and operation), the accrued benefits would 

also outweigh the costs of construction and operation of Units 3 and 4. 

10.7 Staff Conclusions and Recommendations 

The NRC staff’s recommendation to the Commission related to the environmental aspects of the 

proposed action is that the COLs should be issued. The NRC staff’s evaluation of the safety 

and emergency preparedness aspects of the proposed action, which is still ongoing, will be 

addressed in the staff’s safety evaluation report. 

The staff’s recommendation is based on (1) the ER submitted by STPNOC (STPNOC 2010d), 

(2) consultation with Federal, State, Tribal, and local agencies, (3) the review team’s own 

independent review, (4) the staff’s consideration of public comments, and (5) the assessments 

summarized in this EIS, including the potential mitigation measures identified in the ER and in 
Conclusions and Recommendations 

NUREG-1937 10-30 February 2011 

this EIS. In addition, in making its recommendation, the staff determined that none of the 

alternative sites assessed is obviously superior to the STP site. 

The NRC’s determination is independent of the Corps’ determination of a Least Environmentally 

Damaging Practicable Alternative pursuant to Clean Water Act Section 404(b)(1) Guidelines. 

The Corps will conclude its analysis of both offsite and onsite alternatives in its Record of 

Decision. 

10.8 References 

10 CFR Part 50. Code of Federal Regulations, Title 10, Energy, Part 50, "Domestic Licensing of 

Production and Utilization Facilities." 

10 CFR Part 51. Code of Federal Regulations, Title 10, Energy, Part 51, "Environmental 

Protection Regulations for Domestic Licensing and Related Regulatory Functions." 

10 CFR Part 52. Code of Federal Regulations, Title 10, Energy, Part 52, "Licenses, 

Certifications, and Approvals for Nuclear Power Plants." 

33 CFR Part 332. Code of Federal Regulations, Title 10, Navigation and Navigable Waters, Part 

332, “Compensatory Mitigation for Losses of Aquatic Resources.” 

40 CFR Part 1508. Code of Federal Regulations, Title 40, Protection of Environment, Part 

1508, "Terminology and Index." 

72 FR 57416. October 9, 2007. "Limited Work Authorizations for Nuclear Power Plants." 

Federal Register. U.S. Nuclear Regulatory Commission. 

Electric Reliability Council of Texas (ERCOT). 2010a. Electric Reliability Council of Texas 2009 

Annual Report. Austin, Texas. Available at 

http://www.ercot.com/content/news/presentations/2010/2009%20ERCOT%20Annual%20Report

.pdf. 

Electric Reliability Council of Texas (ERCOT). 2010b. Report on the Capacity, Demand, and 

Reserves in the ERCOT Region, System Planning, December 2010, Revision 1. Available at 

http://www.ercot.com/content/news/presentations/2011/ERCOT%202010%20Capacity,%20De

mand%20and%20Reserves%20Report%20-%20Winter%20Upd.pdf. 

Federal Water Pollution Control Act (Clean Water Act). 33 USC 1251, et seq.

Massachusetts Institute of Technology (MIT). 2003. The Future of Nuclear Power: An 

Interdisciplinary MIT Study. Accessed February 4, 2008 at http://web.mit.edu/nuclearpower/. 
 Conclusions and Recommendations 

February 2011 10-31 NUREG-1937 

Massachusetts Institute of Technology (MIT). 2009. Update of The Future of Nuclear Power: 

An Interdisciplinary MIT Study. Accessed July 23, 2009 at 

http://web.mit.edu/nuclearpower/pdf/nuclearpower-update2009.pdf. 

National Environmental Policy Act of 1969, as amended (NEPA). 42 USC 4321, et seq. 

Nuclear Energy Agency, International Energy Agency, and Organization for Economic Cooperation and Development and (NEA IEA and OECD). 2005. Projected Costs of Generating 

Electricity – 2005 Update. International Energy Agency, Paris, France. 

Organization for Economic Co-Operation and Development, Nuclear Energy Agency, and 

International Atomic Energy Agency (OECD NEA and IAEA). 2008. Uranium 2007. 22nd ed., 

Paris, France. 

Rivers and Harbors Appropriation Act of 1899, as amended. 33 USC 403, et seq. 

Scott, M., and M. Niemeyer. 2008. South Texas Project-Interviews with the Public; 

Socioeconomic and Environmental Justice. PNNL-SA-76218, Pacific Northwest National 

Laboratory, Richland, Washington. Accession No. ML092100141. 

South Texas Project Nuclear Operating Company (STPNOC). 2008. Letter from Mark 

McBurnett, STPNOC, to NRC, dated June 9, 2008, “Cultural or Historical Artifact Discovery 

During Construction." Accession No. ML081640213. 

South Texas Project Nuclear Operating Company (STPNOC). 2010a. South Texas Project 

Units 3 and 4 Combined License Application, Part 1, General and Financial Information. 

Revision 4, Bay City, Texas. Accession No. ML102860173. 

South Texas Project Nuclear Operating Company (STPNOC). 2010b. ABWR STP Aircraft 

Impact Assessment (AIA) Amendment. Revision 3, Bay City, Texas. Accession No 

ML102870017. 

South Texas Project Nuclear Operating Company (STPNOC). 2010c. Letter from Scott Head, 

STPNOC, to the U.S. Army Corps of Engineers Galveston District, dated March 9, 2010, “South 

Texas Project Units 3 and 4 Application for Department of Army Permit.” Accession No. 

ML102700237. 

South Texas Project Nuclear Operating Company (STPNOC). 2010d. South Texas Project 

Units 3 and 4 Combined License Application, Part 3, Environmental Report. Revision 4, Bay 

City, Texas. Accession No. ML102860592. 

South Texas Project Nuclear Operating Company (STPNOC). 2010e. Letter from Scott Head, 

STPNOC, to the U.S. Army Corps of Engineers Galveston District, dated October 12, 2010, 
Conclusions and Recommendations 

NUREG-1937 10-32 February 2011 

“South Texas Project Units 3 and 4 SWG-2007-00786 Mitigation Plan.” Accession No. 

ML102060028. 

Southern Nuclear Operating Company, Inc. (Southern). 2008. Southern Nuclear Operating 

Company, Vogtle Early Site Permit Application, Response to NRC Questions from April 23, 

2008 Environmental Conference Call. Letter report from Southern Nuclear Operating Company 

(Birmingham, Alabama) to the U. S. Nuclear Regulatory Commission (Washington, D.C.), June 

26, 2008. Southern Company, Birmingham, Alabama. Accession No. ML081790598. 

Tennessee Valley Authority (TVA). 2008. Bellefonte Nuclear Plant, Units 3 & 4 COL 

Application, Part 3, Environmental Report. Revision 1, Knoxville, Tennessee. Accession No. 

ML083100558. 

University of Chicago. 2004. The Economic Future of Nuclear Power. University of Chicago, 

Chicago, Illinois. Accessed June 20, 2009 at 

http://www.ne.doe.gov/np2010/reports/NuclIndustryStudy-Summary.pdf. 

U.S. Department of Interior, Bureau of Reclamation (USDI/Reclamation). 2008. Construction 

Cost Trends. U.S. Department of Interior, Washington, D.C. Accessed July 7, 2009 at 

http://www.usbr.gov/pmts/estimate/cost_trend.html. Accession No. ML100600715. 

U.S. Department of Energy (DOE). 2004a. “Application of Advanced Construction 

Technologies to New Nuclear Power Plants.” In NP2010 Improved Construction Technologies, 

O&M Staffing and Cost, Decommissioning Costs, and Funding Requirements Study. MPR2610. Washington, D.C. Accession No. ML093160836. 

U.S. Department of Energy (DOE). 2004b. “Study of Construction Technologies and 

Schedules, O&M Staffing and Cost, Decommissioning Costs and Funding Requirements for 

Advanced Reactor Designs.” In NP2010 Improved Construction Technologies, O&M Staffing 

and Cost, Decommissioning Costs, and Funding Requirements Study. Washington, D.C. 

Accession No. ML101820632. 

U.S. Department of Energy (DOE). 2008. Yucca Mountain Repository. Accessed May 2008 at 

http://www.ocrwm.doe.gov/ym_repository/index.shtml#4. Accession No. ML100600704. 

U.S. Department of Energy/Energy Information Administration (DOE/EIA). 2008. Emissions of 

Greenhouse Gases in the United States. DOE/EIA-0573(2008). Accessed February 3, 2010 at 

http://www.eia.doe.gov/oiaf/1605/ggrpt/gwp_gases.html. Accession No. ML100580032. 

U.S. Department of Energy/Energy Information Administration (DOE/EIA). 2010a. Electric 

Power Annual 2009. DOE/EIA-0348 (2009). Energy Information Administration, Washington, 
 Conclusions and Recommendations 

February 2011 10-33 NUREG-1937 

D.C. Accessed December 10, 2010 at 

http://www.eia.doe.gov/cneaf/electricity/epa/epa_sum.html. 

U.S. Department of Energy/Energy Information Administration (DOE/EIA). 2010b. Updated 

Capital Cost Estimates for Electricity Generation Plants. Energy Information Administration, 

Washington, D.C. Accessed December 10, 2010 at 

http://www.eia.doe.gov/cneaf/electricity/epa/epa_sum.html. 

U.S. Environmental Protection Agency (EPA). 2009. Report on the Environment. A-Z 

Indicators List. Accessed on February 3, 2010 at 

http://cfpub.epa.gov/eroe/index.cfm?fuseaction=list.listByAlpha#E. Accession No. 

ML100580033. 

U.S. Nuclear Regulatory Commission (NRC). 2000. Environmental Standard Review Plan —

Standard Review Plans for Environmental Reviews for Nuclear Power Plants, NUREG-1555, 

Vol. 1, Washington, D.C. Includes 2007 updates. 

U.S. Nuclear Regulatory Commission (NRC). 2010. Staff Memorandum from Scott Flanders, 

DSER Division Director, to Brent Clayton, RENV Branch Chief, dated December 10, 2010, 

“Addressing Construction and Preconstruction Activities, Greenhouse Gas Issues, General 

Conformity Determinations, Environmental Justice, Need for Power, Cumulative Impact 

Analysis, and Cultural/Historical Resources Analysis Issues In Environmental Impact 

Statements”. Accession No. ML100760503. 

World Nuclear Association (WNA). 2010. The Economics of Nuclear Power. Accessed 

January 27, 2010 at http://www.world-nuclear.org/info/default.aspx?id=410&terms=price. 

Accession No. ML100600712. 

BIBLIOGRAPHIC DATA SHEET

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NRC FORM 335

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OFFICIAL BUSINESS
NUREG

-1937, Vol. 1

Final 

Environmental Impact Statement for Combined Licenses (COLs) for

South Texas Project Electric Generating Station Units 3 and 4