Environmental Assessment 

Oglethorpe Power Corporation (An Electric 

Membership Corporation) 

Chattahoochee Energy Facility Combustion Turbine Upgrades Project 

11/3/2020 
Environmental Assessment 

prepared for 

Oglethorpe Power Corporation (An Electric 

Membership Corporation) 

Chattahoochee Energy Facility Combustion Turbine 

Upgrades Project 

Franklin, Georgia 

11/3/2020 

prepared by 

Burns & McDonnell Engineering Company, Inc. 

Alpharetta, Georgia 

COPYRIGHT © 2020 BURNS & McDONNELL ENGINEERING COMPANY, INC. 
Table of Contents 

Oglethorpe Power TOC-1 

Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

TABLE OF CONTENTS 

Page No. 

1.0 INTRODUCTION ............................................................................................... 1-1

1.1 Project Description ............................................................................................... 1-2

1.2 Purpose and Need ................................................................................................ 1-3

1.2.1 Oglethorpe Power Purpose and Need ................................................... 1-3

1.2.2 RUS Potential Funding Action ............................................................. 1-4

2.0 ALTERNATIVES EVALUATED ........................................................................ 2-1

2.1 Proposed Action ................................................................................................... 2-1

2.2 Other Alternatives Evaluated ............................................................................... 2-1

2.3 No Action Alternative .......................................................................................... 2-2

3.0 AFFECTED ENVIRONMENT AND ENVIRONMENTAL CONSEQUENCES .... 3-1

3.1 Aesthetics ............................................................................................................. 3-1

3.2 Air Quality ........................................................................................................... 3-1

3.2.1 Affected Environment ........................................................................... 3-2

3.2.2 Environmental Consequences ............................................................... 3-2

3.2.3 Mitigation .............................................................................................. 3-4

3.3 Floodplains ........................................................................................................... 3-4

3.4 Geology, Soils, and Farmland .............................................................................. 3-4

3.5 Historic and Cultural Resources .......................................................................... 3-5

3.6 Human Health and Safety .................................................................................... 3-5

3.7 Land Use .............................................................................................................. 3-5

3.8 Noise .................................................................................................................... 3-5

3.9 Socioeconomics and Environmental Justice ........................................................ 3-6

3.9.1 Socioeconomics .................................................................................... 3-6

3.9.2 Environmental Justice ........................................................................... 3-6

3.9.3 Utilities ................................................................................................ 3-10

3.9.4 Mitigation ............................................................................................ 3-12

3.10 Threatened and Endangered Species ................................................................. 3-12

3.11 Transportation .................................................................................................... 3-13

3.12 Vegetation .......................................................................................................... 3-13

3.13 Water Resources and Wetlands ......................................................................... 3-14

3.14 Wildlife .............................................................................................................. 3-14

4.0 CUMULATIVE EFFECTS .................................................................................. 4-1

4.1 Cumulative Impacts by Resource ........................................................................ 4-2

4.1.1 Aesthetics .............................................................................................. 4-2

4.1.2 Air Quality ............................................................................................ 4-2

4.1.3 Floodplains ............................................................................................ 4-2

4.1.4 Geology, Soils, and Farmland ............................................................... 4-2

4.1.5 Historical and Cultural Resources ........................................................ 4-3
Table of Contents 

Oglethorpe Power TOC-2 

Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

4.1.6 Human Health and Safety ..................................................................... 4-3

4.1.7 Land Use ............................................................................................... 4-3

4.1.8 Noise ..................................................................................................... 4-3

4.1.9 Socioeconomics and Environmental Justice ......................................... 4-3

4.1.10 Threatened and Endangered Species .................................................... 4-3

4.1.11 Transportation ....................................................................................... 4-4

4.1.12 Vegetation ............................................................................................. 4-4

4.1.13 Water Resources and Wetlands ............................................................ 4-4

4.1.14 Wildlife ................................................................................................. 4-4

5.0 SUMMARY OF MITIGATION ............................................................................ 5-1

6.0 PUBLIC INVOLVEMENT .................................................................................. 6-1

7.0 LIST OF PREPARERS ..................................................................................... 7-1

8.0 REFERENCES .................................................................................................. 8-1

APPENDIX A - MEMO ADDRESSING IMPACTS TO CULTURAL 

RESOURCES

APPENDIX B – TITLE V SIGNIFICANT MODIFICATION WITH 

CONSTRUCTION APPLICATION

APPENDIX C – FEMA FIRMETTE FLOOD MAP

APPENDIX D – USFWS IPAC DOCUMENTATION

APPENDIX E – NWI MAP

LIST OF TABLES 

Page No. 

Table 3.2-1: PSD Permitting Determination ............................................................................... 3-3

Table 3.9-1: Minority and Low-Income Populations near the Project in Carroll County .......... 3-7

Table 3.9-2: Minority and Low-Income Populations near the Project in Heard County ............ 3-7

Table 3.9-3: Minority and Low-Income Populations near the Project in Coweta County ......... 3-7

Table 3.9-4: Daily Treated Wastewater Usage and Discharges (thousand gal) ....................... 3-11

Table 3.10-1:Protected Species Potentially occurring in Carroll and Heard Counties .............. 3-12

LIST OF FIGURES 

Page No. 

Figure 1-1: Project Location Map ............................................................................................. 1-5

Figure 3-1: Census Blocks Included in Environmental Justice ................................................ 3-7 
 

Oglethorpe Power i Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

LIST OF ABBREVIATIONS 

Abbreviation Term/Phrase/Name 

AAC Acceptable Air Concentration 

BACT Best Available Control Technology 

Burns & McDonnell Burns & McDonnell Engineering Company, Inc. 

CCCT Combined-cycle combustion turbine 

CEQ Council on Environmental Quality 

CFR Code of Federal Regulations 

CO Carbon monoxide 

CO2e Carbon dioxide equivalents 

EMC Electric membership corporation 

EPA U.S. Environmental Protection Agency 

EPD Environmental Protection Division 

Facility Chattahoochee Energy Facility 

FEMA Federal Emergency Management Agency 

FONSI Finding of No Significant Impact 

FWS U.S. Fish and Wildlife Service 

GDNR Georgia Department of Natural Resources 

GHG Greenhouse gases 

H2SO4 Sulfuric acid 

IPaC Information for Planning & Consultation System 

LLTD Low Load Turndown 

LVWW Low-volume wastewater 

MER Minimum Emission Rate 

MW Megawatts 

NAAQS National Ambient Air Quality Standards 

NEPA National Environmental Policy Act 

NO2 Nitrogen dioxide 

NOX Nitrogen oxides 
 Introduction 

Oglethorpe Power ii Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

Abbreviation Term/Phrase/Name 

NPDES National Pollutant Discharge Elimination System 

NSA Noise Sensitive Area 

NSPS New Source Performance Standards 

NSR New Source Review 

NWI National Wetlands Inventory 

O2 Oxygen 

Oglethorpe Oglethorpe Power Corporation 

PM2.5 Particulate matter less than 2.5 microns in diameter 

PM10 Particulate matter less than 10 microns in diameter 

ppm Parts per million 

Program RUS Electric Loan Program 

Project The Combustion Turbine Upgrades Project 

PSD Prevention of Significant Deterioration 

RE Act Rural Electrification Act 

RUS Rural Utilities Service 

SER Significant Emission Rate 

SO2 Sulfur dioxide 

TAP Toxic air pollutants 

TIA Toxic Impact Assessment 

TPU1 Thermal Performance Upgrade Step 1 

tpy Tons per year 

USC United States Code 

USDA U.S. Department of Agriculture 

VOC Volatile organic compounds 
 Introduction 

Oglethorpe Power 1-1 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

1.0 INTRODUCTION 

Oglethorpe Power Corporation (Oglethorpe) is seeking financing assistance from the Rural Utilities 

Service (RUS) to make software and hardware upgrades at its existing Chattahoochee Energy Facility 

(Facility), a 502 megawatt (MW) gas-fired combined-cycle power generating facility, on Liberty Church 

Road in Heard County at coordinates 33.4070°N; 85.0387°W near Franklin, Georgia. The Facility’s 

Combustion Turbine Upgrades Project (Project) would increase the current generation capacity of the 

Facility to approximately 525 MW. This projected capacity increase is based on 59-degree Fahrenheit 

conditions and will vary slightly under differing ambient temperatures. The Project will help reduce the 

overall cost per MW of power generated, and allow the Facility’s gas turbines to continue to operate at 

reduced power during times of low demand with less frequent shutdowns and subsequent restarts once 

demand increases. This Environmental Assessment (EA) describes the alternatives evaluated, the affected 

environment, potential environmental consequences, cumulative effects, mitigation measures, and agency 

scoping for the Project. 

The RUS action is the decision to provide financing assistance for the Project. Under the Rural 

Electrification Act (RE Act), as amended, the Secretary of Agriculture is authorized and empowered to 

make loans to nonprofit cooperatives and others for rural electrification “for the purpose of financing the 

construction and operation of generating plants, electric transmission and distribution lines, or systems for 

the furnishing and improving of electric service to persons in rural areas” (7 U.S. Code [USC] § 904). A 

primary function or mission of RUS is to carry out this electric loan program (7 USC § 6942). 

Oglethorpe, which is headquartered in Tucker, Georgia, is a generation cooperative operating on a notfor-profit basis that generates electricity for 38 of Georgia’s electric membership cooperatives (EMCs). 

Oglethorpe’s objective is to provide reliable energy to its EMC members to meet their existing and 

expanding power supply needs. The Facility, on Liberty Church Road in Heard County near the city of 

Franklin, Georgia, is an approximately 13-acre natural gas generation block owned and operated by 

Oglethorpe (see Figure 1-1). The Facility is co-located on 5,200 acres with the Plant Wansley coal-fired 

power plant operated by Georgia Power (a subsidiary of Southern Company) and three other natural gas 

generation blocks owned and operated by other entities. Surrounding lands include the Chattahoochee 

River, streams, planted pine, woodland, agricultural, and forested wetlands. The Chattahoochee River is 

located approximately 2,500 feet southeast of the Facility. The Facility was constructed by Oglethorpe 

and commenced commercial operations in 2003. 
 Introduction 

Oglethorpe Power 1-2 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

Oglethorpe intends to finance this Project under the RUS Electric Loan Program (the Program). As a 

result, the Project represents a Federal action that must be reviewed under the National Environmental 

Policy Act (NEPA) of 1969. The responsible agency will be the RUS. This EA has been prepared in 

compliance with RUS policies and Procedures, 7 Code of Federal Regulations (CFR) Part 1970 and the 

Council on Environmental Quality (CEQ) Regulations for implementation of NEPA 40 CFR Parts 1500-

1508. As part of its broad environmental review process, RUS must also take into account the effect of 

the Project on historic properties in accordance with Section 106 of the National Historic Preservation Act 

and its implementing regulation, “Protection of Historic Properties” (36 CFR Part 800). RUS has made a 

finding that this project has “No Potential to Effect” historic properties or cultural resources because it 

does not involve ground disturbing activities and all activities are undertaken within the existing facility, 

as indicated in the memo provided in Appendix A. Pursuant to 36 CFR § 800.2(d)(3), there is no Section 

106 requirement for public comment once RUS determines “No Potential To Effect.” 

1.1 Project Description 

The proposed Project would involve the implementation of two upgrades for the Chattahoochee Energy 

Facility’s two combustion turbines: the Thermal Performance Upgrade Step 1 (TPU1) and the Low Load 

Turndown (LLTD) upgrade. The TPU1 would improve plant output and heat rate and extend the 

maintenance interval of the units by installing enhanced hardware in the gas turbines, replacing certain 

auxiliary hardware components, and adding site-specific control logic optimizations. New turbine 

hardware would include combustion chamber components with optimized cooling air reduction, 

impingement cooled tile holders, the latest ceramic heat shields, metallic heat shields, and burner swirlers 

with reduced swirl angle. Auxiliary hardware replacements would include the pilot gas flow meter, an 

advanced combustion dynamic monitoring system, heat resistant ignition cables, blow-off valve actuators, 

and additional pressure and acceleration measurement instrumentation. These changes would increase the 

existing capacity of the Facility by approximately 23 MW to a total capacity of approximately 525 MW, 

with slight variations from ambient temperatures, and lower the cost to Oglethorpe’s 38 EMC members. 

The LLTD upgrades would allow the gas turbines to operate at steady-state minimum loads of 

approximately 67 MW, with variations for ambient temperatures, while continuing to maintain emissions 

concentrations of nitrogen oxides (NOX) and carbon monoxide (CO) in compliance with the Facility’s 

permitted emission limits. Currently, the Facility shuts down periodically during low demand and then 

restarts when demand increases. The LLTD upgrades would involve installation of new gas turbine 

components and software controls to replace selected equipment and connected accessories to allow 

sustained operations at lower operating loads during periods of low demand. These changes would 

include compressor inlet guide vane extended range sensor, ring modification and linearization unit 
 Introduction 

Oglethorpe Power 1-3 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

replacement, and the addition of a gas turbine exhaust metallic heat shield, along with site-specific control 

logic optimizations. This upgrade would allow the Facility to continue to operate with less frequent 

shutdowns during low demand periods, thereby reducing maintenance and fuel costs associated with 

cycling through unit shutdowns and startups. Neither the TPU1 nor the LLTD upgrades would increase 

the expected lifespan of the Facility. 

This Project would result in increases in maximum heat input and maximum projected annual air 

emissions. A small increase in water usage and water discharges is also expected. It is anticipated the 

Project may result in an increase in maximum short-term emissions, and Oglethorpe is permitting the 

Project as a modification under the federal New Source Performance Standards (NSPS) regulations. As 

such, the combustion turbines and associated duct burners would be subject to the NSPS in 40 CFR 60 

Subpart KKKK, Standards of Performance for Stationary Combustion Turbines, after completion of the 

Project. The Facility’s Title V permit includes more stringent NOX emission limits than the limits under 

Subpart KKKK. Therefore, the Facility will use its existing air pollution control devices and emissions 

monitoring systems to comply with Subpart KKKK. No installation of new devices or equipment is 

required. 

Implementation of the Project is not expected to increase the noise from the Facility above historical 

levels, nor would it require changes in the infrastructure for gas supply, electrical transmission, or water 

usage/discharge. The Project would involve software and mechanical upgrades to existing equipment 

within the current Facility structures. Oglethorpe has consulted with Georgia Transmission Corporation 

and confirmed that the introduction of the additional power to the integrated transmission system would 

not cause system impacts and that no infrastructure upgrades would be necessary to support the Project. 

No new ground-disturbing activities or new facilities, equipment, or buildings would be constructed 

within or outside the current Facility footprint. As a result, the Project would not impact biological 

resources, soils and geological resources, cultural resources, socioeconomic resources, hazardous 

materials, or wetlands. 

1.2 Purpose and Need 

1.2.1 Oglethorpe Power Purpose and Need 

Oglethorpe is responsible for providing reliable, efficient, and low-cost power to the 38 EMC members of 

the not-for-profit generation cooperative who provide power to over 4 million Georgians. Oglethorpe 

continues to evaluate methods for increasing the reliability and efficiency of their power generation while 

continuing to lower costs to their members. 
 Introduction 

Oglethorpe Power 1-4 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

The proposed Project would increase capacity at the existing Facility and allow Oglethorpe to meet 

system demand with the Facility operating rather than starting other less efficient units, purchasing power 

from others, or constructing new generation. The Project would lower maintenance costs, reduce start-up 

costs because the Facility would have to shut down less often, and improve the Facility’s overall 

operating efficiency. 

The additional capacity at lower costs would meet the need of providing more efficient and less expensive 

power to its members and the Georgians they serve. 

1.2.2 RUS Potential Funding Action 

Utilities can seek financial assistance for capital projects that meet the U.S. Department of Agriculture 

(USDA) Rural Development objectives. The Rural Electrification Act of 1936 allows for the Secretary of 

Agriculture, through RUS, to approve loans, loan guarantees, grants, and other project financing to 

electric utilities and projects that serve rural communities. Oglethorpe may seek financial assistance for 

the Project from this Program to increase capacity and lower maintenance costs to its 38 EMC members. 

RUS’ reviews of financial assistance applications include information ranging from purpose and need of 

the Project, engineering feasibility of the Project, cost, alternatives considered, to environmental impacts, 

and other applicable topics. RUS uses these reviews and analyses to determine whether to provide 

financing assistance to a project, which is a federal action for RUS. RUS’ financial decision for the 

Project is based on funds available in the agency’s budget. Therefore, publication of the EA and execution 

of environmental findings does not constitute an approval of funds for the Project but is required before 

financing is provided, should funds be available. 
 Introduction 

Oglethorpe Power 1-5 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

Figure 1-1: Project Location Map
 Alternatives Evaluated 

Oglethorpe Power 2-1 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

2.0 ALTERNATIVES EVALUATED 

In accordance with NEPA and RUS policies, Oglethorpe considered alternatives to the Project to 

determine if an alternative would be environmentally preferable, reasonable, and/or technically and 

economically feasible to the proposed action. As the proposed action does not require any new ground 

disturbances or construction of new facilities, site alternatives are not further discussed. Oglethorpe 

evaluated the no action alternative and compared it to the proposed action using three criteria: 

1. Would the no action alternative meet the objectives of the proposed action? 

2. Would the no action alternative offer a significant environmental advantage over the proposed 

action? 

3. Would the no action alternative be technically and economically feasible, reasonable, and 

practical? 

2.1 Proposed Action 

The proposed action includes hardware and software upgrades to the combined-cycle Facility to improve 

the performance, heat rate, and capacity of the turbines, and allow them to continue to operate during 

periods of low demand to reduce the frequency of shutdowns. Oglethorpe has consulted with Georgia 

Transmission Corporation, confirming the existing grid infrastructure will accept increased power output 

from the Facility. The proposed upgrades will allow Oglethorpe to provide generation at a lower price per 

MW of power generated. 

The mechanical upgrades would be performed during one of the routine major outages at the Facility that 

occur after a certain number of operating hours or approximately every 8 years. During a major outage, 

the Facility is shut down for a longer period of time and a larger number of contractors and personnel are 

brought to the Facility to perform maintenance, and upgrades if applicable. The contractors performing 

the major outage would also perform the mechanical upgrades for the Project, and a permanent increase 

in personnel at the Facility is not proposed. One or two one-time shipments of mechanical equipment may 

also be required to install these mechanical upgrades, but no significant increases in traffic or equipment 

is proposed. 

2.2 Other Alternatives Evaluated 

This EA does not look at alternative sites for increased capacity, as a new site would require the 

construction of a large amount of infrastructure (transmission, water intake, etc.) that currently exists at 

the Facility site. Increasing capacity at other existing facilities could also potentially require significant 
 Alternatives Evaluated 

Oglethorpe Power 2-2 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

infrastructure upgrades resulting in more environmental impacts associated with the upgrades. 

Additionally, the Chattahoochee Energy Facility is Oglethorpe’s least expensive generation source and 

therefore the most operated units. As such, performing these upgrades at this site will result in more use 

of the additional capacity than if upgrades were available and were installed at other sites. 

2.3 No Action Alternative 

Under the no action alternative, the software and mechanical upgrades associated with Project would not 

be implemented, and the Facility would continue to operate in its current state. Therefore, the capacity 

would not increase and the price per MW of power generated would not decrease as a result of efficiency 

improvements from the Project. Oglethorpe may need to start other units or purchase power from others 

to meet the system demands. Additionally, the Facility would not be able to remain online through 

periods of low demand resulting in more shutdowns and startups, and, in turn, increased wear and tear on 

the equipment. For these reasons, the no action alternative is not preferable to or does not provide a 

significant environmental advantage over the proposed action, and it is not recommended. 
 Affected Environment and Environmental Consequences 

Oglethorpe Power 3-1 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

3.0 AFFECTED ENVIRONMENT AND ENVIRONMENTAL CONSEQUENCES 

The Project would occur within the boundaries and buildings of the current Facility and would involve 

software and mechanical upgrades to existing computer and generation equipment. It would not impact 

biological resources, soils and geological resources, cultural resources, socioeconomic resources, 

hazardous materials, wetlands, infrastructure for water usage or discharge, noise emissions above 

historical levels, or gas supply infrastructure. The following discusses a variety of natural and social 

resources and the potential project-related consequences to each. 

3.1 Aesthetics 

As shown in the aerial imagery on Figure 1-1, the Project would occur inside of the existing Facility. 

The surrounding land use is considered industrial and includes adjacent natural gas generating units as 

well as the Plant Wansley coal-fired power plant. Since there would be no changes to the current or future 

aesthetics within or surrounding the Facility, no impact on the aesthetic environment would occur as a 

result of the Project. No environmental consequences would occur, and no mitigation is proposed. 

3.2 Air Quality 

The current air quality of the area surrounding the Facility along with the anticipated impacts on air 

quality as a result of the Project are discussed in the following sub-sections. 

Ambient air quality is protected by federal and state regulations. The U.S. Environmental Protection 

Agency (EPA) established National Ambient Air Quality Standards (NAAQS) to protect human health 

and welfare. Primary standards protect human health, including the health of defined sensitive 

populations, such as asthmatics, children, and the elderly. NAAQS have been developed for sulfur 

dioxide (SO2), particulate matter (PM) with a diameter of 10 microns or less (PM10), PM with a diameter 

of 2.5 microns or less (PM2.5), nitrogen dioxide (NO2), carbon monoxide (CO), ozone, and lead, and 

include levels for short-term (acute) and long-term (chronic) exposures as applicable. Ozone is not a 

pollutant emitted directly into the air. It is formed from a chemical reaction involving nitrogen oxides 

NOX and volatile organic compounds (VOC) in the presence of sunlight. Consequently, emissions of NOX

and VOCs are regulated by the EPA as “precursors” to the formation of ground-level ozone. VOC means 

any compound of carbon (excluding CO, carbon dioxide [CO2], carbonic acid, metallic carbides or 

carbonates, and ammonium carbonate) which participates in atmospheric photochemical reactions (40 

CFR 51.100s). The current NAAQS are listed on the EPA’s website (EPA, 2020a). 
 Affected Environment and Environmental Consequences 

Oglethorpe Power 3-2 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

3.2.1 Affected Environment 

New Source Review (NSR) is a pre-construction permitting program designed to protect air quality when 

air pollutant emissions are increased either through the modification of existing sources or through the 

construction of a new source of air pollution. In areas with good air quality, NSR ensures that the new 

emissions do not significantly degrade the air quality. This is achieved through the implementation of the 

Prevention of Significant Deterioration (PSD) permitting program or state minor permit programs. In 

areas with poor air quality, Nonattainment NSR ensures that the new emissions do not inhibit progress 

toward cleaner air. In addition, NSR ensures that any new or modified large industrial source uses the 

Best Available Control Technology (BACT) to reduce its air emissions. Air permitting of stationary 

sources has been delegated to each state and/or local permitting authority. The Facility is considered a 

PSD major source because it has potential emissions of multiple regulated pollutants exceeding the major 

source threshold of 100 tons per year (tpy) for a listed source (fossil fuel-fired steam electric plants of 

more than 250 million British thermal units per hour heat input). Additionally, the Facility is considered a 

major source of NOX emissions under the Georgia Nonattainment NSR permitting program because it has 

potential emissions of NOX exceeding 100 tpy, contains electric generating units, and is located in an area 

(Heard County) contributing to the ambient air level of ozone in the metropolitan Atlanta ozone 

nonattainment area (Georgia Air Quality Control Rule 391-3-1-.03(8)(c)(15)). Therefore, a NSRemissions increase analysis is required to determine whether PSD permitting and/or Nonattainment NSR 

permitting applies to the Project. 

3.2.2 Environmental Consequences 

The Project would result in increases in maximum heat input and maximum projected annual emissions 

from the combined cycle combustion turbines (CCCTs). It is anticipated the Project may also result in an 

increase in maximum short-term emissions. Annual emissions increases from the Project were evaluated 

using the actual-to-projected applicability test defined in the federal PSD regulations. Specifically, 

emissions increases were calculated as the difference between maximum projected actual and baseline 

actual emissions, excluding the portion of emissions following the project that the unit could have 

accommodated prior to the Project and that are unrelated to the Project. The federal PSD regulations 

define “projected actual emissions” as the maximum annual rate at which an existing unit is projected to 

emit a regulated NSR pollutant in any of the 10 years following the date the unit resumes regular 

operation after the project (40 CFR 52.21(b)(41)(i)). As such, the emissions increase estimates for the 

Project are conservatively high, because they are based on the future maximum projection of actual 

emissions, not the future expected or most likely actual emissions. 
 Affected Environment and Environmental Consequences 

Oglethorpe Power 3-3 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

The resulting analysis calculates maximum increases for each pollutant at levels lower than their 

respective PSD Significant Emission Rates (SER), and it has therefore been determined that PSD 

permitting will not be required for the Project. Oglethorpe has prepared and submitted to the Georgia 

Environmental Protection Division (EPD) a Title V Significant Modification with Construction 

Application for the Project (Appendix B). Further, the Project emissions increase for NOX is less than the 

Nonattainment NSR SER, and, as a result, the Nonattainment NSR permitting is also not required for the 

Project. Note that the applicable SER for NOX is the same under both the PSD and the Nonattainment 

NSR permitting programs (40 tpy). 

A comparison of the emissions increase from the Project for each pollutant to its SER is provided in 

Table 3.2-1, below. 

Table 3.2-1: PSD Permitting Determination 

Pollutant 

CCCT 

Baseline 

Actual 

Emissions 

(tpy) 

CCCT 

Projected 

Actual 

Emissions 

(tpy) 

CCCT 

Emissions that 

Could Have 

Been 

Accommodated 

(tpy) 

CCCT 

Demand 

Growth 

Exclusion 

(tpy) 

CCCT 

Project 

Emissions 

Increase(a)

(tpy) 

Cooling 

Tower 

Associated 

Emissions 

Increase(b)

(tpy) 

Total 

Project 

Emissions 

Increase 

(tpy) 

NSR 

SER 

(tpy) 

NSR 

Permitting 

Required? 

NOX 100.2 153.1 116.4 16.2 36.7 -- 36.7 40 No 

CO 19.0 67.6 30.0 11.0 37.6 -- 37.6 100 No 

PM 69.7 90.6 81.1 11.4 9.5 0.31 9.8 25 No 

PM10 69.7 90.6 81.1 11.4 9.5 0.27 9.8 15 No 

PM2.5 69.7 90.6 81.1 11.4 9.5 0.0015 9.5 10 No 

VOC 11.6 15.1 13.5 1.9 1.6 -- 1.6 40 No 

SO2 7.0 9.1 8.1 1.1 0.95 -- 0.95 40 No 

H2SO4 0.80 1.0 0.93 0.13 0.11 -- 0.11 7 No 

CO2e 1,382,762 1,796,567 1,608,206 225,444 188,361 -- 188,361 75,000 No(c)

(a) CCCT Project Emissions Increase (tpy) = CCCT Projected Actual Emissions (tpy) - CCCT Demand 

Growth Exclusion (tpy) - CCCT Baseline Actual Emissions (tpy) 

(b) The cooling tower will have an associated emissions increase due to increases in drift loss following the 

Project. There are no modifications to the cooling tower occurring as part of this Project. 

(c) PSD permitting for CO2e is only required if 1) the emissions increase exceeds the SER of 75,000 tpy AND 

2) the project triggers PSD anyway for at least one other PSD-regulated pollutant. 

Source: Title V Significant Modification with Construction Application (Appendix B)

Since the Project does not require PSD or Nonattainment NSR permitting, Oglethorpe is not required to 

evaluate BACT for its CCCTs or perform an ambient air quality analysis. However, because the Project 

may result in an increase in maximum short-term emissions, Oglethorpe is permitting the Project as a 

modification under the federal New Source Performance Standards (NSPS) regulations. Both CCCTs 

would be subject to the NSPS in 40 CFR 60 Subpart KKKK, Standards of Performance for Stationary 

Combustion Turbines, following the completion of the Project. The NOX emission limits under Subpart 

KKKK (15 ppm at 15% oxygen [O2] when operating at or above 75% of peak load; 96 ppm at 15% O2
 Affected Environment and Environmental Consequences 

Oglethorpe Power 3-4 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

when operating below 75% of peak load) would be subsumed by the more stringent existing NOX

emission limit under the Facility’s Title V permit (3.0 ppm at 15% O2). The Facility will use its existing 

air pollution control devices and emissions monitoring systems to comply with Subpart KKKK. No 

installation of new devices or equipment is required. 

Oglethorpe has submitted an application to the Georgia EPD seeking a combined Title V operating permit 

modification and state construction permit, which will authorize the construction and operation of the 

proposed Project and incorporate the requirements of 40 CFR 60 Subpart KKKK into the Facility’s 

permit. The application, provided in Appendix B, outlines the methodology used to evaluate the Project 

emissions increase, details the requirements of 40 CFR 60 Subpart KKKK, and includes a Toxic Impact 

Assessment (TIA) in accordance with state guidelines. In the TIA, the potential emissions of individual 

toxic air pollutants (TAPs) from the Facility’s operations are compared to each TAP’s Minimum 

Emission Rate (MER) in Appendix A to the TIA guidelines. For each TAP with potential emissions 

exceeding the MER, screening modeling (SCREEN3) is then used to demonstrate that the ambient impact 

from the Facility’s operations is well below the TAP’s Acceptable Ambient Concentration (AAC) in 

Appendix A in the TIA guidelines. 

3.2.3 Mitigation 

The Project will not require a NSR permit. No new ground-disturbing activities are proposed for the 

Project, and there will be no emissions associated with earth-moving for construction. Therefore, no 

mitigation is proposed in connection with the Project. However, the Facility will continue to utilize its 

existing air emission control measures, including dry low NOX combustors on the turbines and low NOX

duct burners, selective catalytic reduction (SCR) for NOX emissions control, catalytic oxidation for CO 

and VOC emissions control, and the use of low-sulfur fuel (natural gas), , in accordance with the 

Facility’s existing air permits. 

3.3 Floodplains 

The Project would occur within the existing footprint of the Facility, which is not located within a 

floodplain as indicated on FEMA Firmette Flood Map 1314900C70D, effective 4/19/2017 (Appendix D). 

No floodplains would be affected by the Project. Since the Project is not located within a floodplain and 

no impact on floodplains would occur as a result of the Project, no floodplain mitigation is proposed. 

3.4 Geology, Soils, and Farmland 

The Project would occur within the existing footprint of the Facility, and there would be no grounddisturbing impacts or new facilities, equipment, or buildings constructed within or outside the current 
 Affected Environment and Environmental Consequences 

Oglethorpe Power 3-5 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

Facility footprint. Additionally, no hazardous materials or petroleum products would be used for the 

Project. All Project activities would occur within existing building and any spills would be contained and 

cleaned up immediately, preventing exposure of any potentially hazardous substances to soils. No 

impacts would occur to geology, soils, or farmland as a result of the Project, and no mitigation is 

proposed. 

3.5 Historic and Cultural Resources 

No impacts beyond the existing Facility footprint are proposed. Though this project reaches an 

Environmental Assessment level of review, the RUS Federal Preservation Officer, has reviewed the 

project scope and has determined that the Project would meet the criteria for “No Potential to Effect” 

historic properties or cultural resources (Appendix A) because there is no ground disturbance involved 

and activities take place entirely within the inside of the facility. Therefore, no impacts on important 

cultural, archeological, or paleontological resources that are listed or eligible for listing in the National 

Register of Historic Places would occur as a result of the Project, and no mitigation is proposed. 

3.6 Human Health and Safety 

The Project would occur within the existing footprint of the Facility; and there would be no grounddisturbing impacts within or beyond the existing footprint. The Project will result in an increase in air 

emissions, and Oglethorpe has submitted an application for a Title V permit modification with 

construction for the Project to the Georgia EPD. Georgia EPD is the agency responsible for protecting 

Georgia’s air quality through the regulation of air emissions from industrial and mobile sources. 

Oglethorpe will obtain an air permit from Georgia EPD prior to commencing the Project and will comply 

with all applicable air regulations and permit requirements in order to protect public health. As a result, 

there would be no impacts or environmental consequence to human health and safety as a result of the 

Project, and no mitigation is proposed. 

3.7 Land Use 

The Project would not result in the temporary or permanent conversion of existing land use types; 

therefore, no impacts on land use would occur, and no mitigation is proposed. 

3.8 Noise 

The Project would not result in increased noise levels above historical levels at noise sensitive areas 

(NSAs). The nearest NSA (Yellow Dirt Baptist Church at 4058 Hollingsworth Ferry Road in Franklin, 

Georgia) is approximately 1.2 miles from the Facility; therefore, no noise impacts to NSAs would occur, 

and no mitigation is proposed. 
 Affected Environment and Environmental Consequences 

Oglethorpe Power 3-6 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

3.9 Socioeconomics and Environmental Justice 

3.9.1 Socioeconomics 

Socioeconomics includes population growth trends, racial and ethnic characteristics, employment, 

income, public services (education facilities, medical facilities, fire protection, police protection), and 

recreation and open space. The Project includes software and mechanical upgrades to existing equipment 

during a routine outage and would not result in any changes or impacts to population trends, racial and 

ethnic characteristics, employment, public services, or recreational spaces. 

3.9.2 Environmental Justice 

3.9.2.1 Affected Environment 

Executive Order 12898, titled Federal Actions to Address Environmental Justice in Minority Populations 

and Low-Income Populations and issued in 1994, directs Federal agencies to take the appropriate and 

necessary steps to identify and address disproportionately high and adverse effects of Federal projects on 

the health or environment of minority and low-income populations to the greatest extent practicable and 

permitted by law. For the purpose of this analysis, minority is defined as individuals who identify as a 

race other than white alone (single race) and/or identify their ethnicity as Hispanic or Latino. Low-income 

is defined as a household income less than or equal to twice the Federal poverty level. 

The area was screened for the presence of minority and low-income populations using the EPA 

EJSCREEN tool (EPA, 2018). The tool contains demographic indexes, including percent low-income and 

percent minority, based on the U.S. Census 2013-2017 ACS 5-Year Estimates. The Project is located near 

seven U.S. Census block groups: 130459108002, 130459109001, 130459109002, 130771701003, 

131499701003, 131499702001, and 131499702002, as depicted in Figure 3-1. These census block 

groups span the counties of Heard, Carroll, and Coweta. For this environmental justice analysis, the block 

group was considered an environmental justice minority area if either (1) the minority population 

exceeded 50 percent, or (2) the minority population was greater than 10 percentage points of benchmark 

or reference region. The block group was considered an environmental justice low-income area if its 

population was greater than 10 percentage points of the benchmark or reference region. For this analysis, 

the benchmark geographic areas are the counties and state (Georgia) within which each block group is 

located. 
 Affected Environment and Environmental Consequences 

Oglethorpe Power 3-7 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

A comparison of the percent minority and low-income for the block groups, Heard County, and State is 

provided in Table 3.9-1. Table 3.9-2 provides a comparison for the block groups in Carroll County, and 

Table 3.9-3 provides a comparison for the block group in Coweta County. 

Table 3.9-1: Minority and Low-Income Populations near the Project in Carroll County 

Geographic Area 

Minority population 

(percent) 

Low-income population 

(percent) 

Georgia 46 37 

Carroll County 29 41 

Carroll County Block Group 

130459109001 9 34 

Carroll County Block Group 

130459109002 4 45 

Carroll County Block Group 

130459108002 10 32 

Source: Environmental Protection Agency, 2020b; U.S. Census Bureau 2013-2017 5-Year Estimates\ 

Table 3.9-2: Minority and Low-Income Populations near the Project in Heard County 

Geographic Area 

Minority population 

(percent) 

Low-income population 

(percent) 

Georgia 46 37 

Heard County 15 43 

Heard County Block Group 

131499702002 2 27 

Heard County Block Group 

131499702001 18 47 

Heard County Block Group 

131499701003 1 43 

Source: Environmental Protection Agency, 2020b; U.S. Census Bureau 2013-2017 5-Year Estimates
 Affected Environment and Environmental Consequences 

Oglethorpe Power 3-8 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

Table 3.9-3: Minority and Low-Income Populations near the Project in Coweta County 

Geographic Area 

Minority population 

(percent) 

Low-income population 

(percent) 

Georgia 46 37 

Coweta County 28 28 

Coweta County Block Group 

130771701003 30 32 

Source: Environmental Protection Agency, 2020b; U.S. Census Bureau 2013-2017 5-Year Estimates

3.9.2.2 Environmental Consequences 

No environmental justice minority or low-income areas were identified near the Project in Carroll County 

and Coweta County. No environmental justice minority areas were identified in Heard County. The Heard 

County Block Group 131499702001, as depicted in Figure 3-1, is considered an environmental justice 

low-income area because the low-income population is 10 percentage points greater than the low-income 

population in Georgia overall. However, the Project would not have disproportionately high and adverse 

impact on the environmental justice communities in the area because the Project involves only software 

and mechanical upgrades inside the existing Facility, and there will be no new ground disturbing impacts. 

Although the Plant Wansley coal-fired power plant is within Census Block Group 131499702001, the 

Facility is within a small area of the block group and there are few residents in the surrounding area. Due 

to the lack of residences in this area and the existing small footprint of the Project within the Census 

Block Group 131499702001, it is anticipated that the Project would have no adverse impacts on 

environmental justice communities in this area. 
 Affected Environment and Environmental Consequences 

Oglethorpe Power 3-9 Cha

Combustion 

Figure 3-1: Census Blocks Included in Environmental Justice Analysis 
 Affected Environment and Environmental Consequences 

Oglethorpe Power 3-10 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

3.9.3 Utilities 

3.9.3.1 Affected Environment 

Public utilities include potable water, treated wastewater, sanitary sewer, electricity, gas, and solid waste 

services. The Project would not result in any changes or impacts to potable water, sanitary sewer, 

electricity, and solid waste services. There would be changes to the quantity of natural gas received, 

although no changes to the existing gas supply line infrastructure would be required to support the 

Project. The air emissions impacts from the increased natural gas consumption were previously outlined 

in Section 3.2 of this EA. Additionally, there would be an increase in the total treated surface water 

supplied for the cooling towers. 

Georgia Power withdraws surface water from the Chattahoochee River (under State Water Quality 

Control Permit No. 074-1291-06) to replenish the Service Water Reservoir on Yellowdirt Creek (north of 

the Wansley coal-fired power plant). Georgia Power then withdraws water from the Service Water 

Reservoir to supply cooling tower makeup and general service water for on-site operations including the 

Facility’s operations (under State Water Quality Control Permit No. 074-1291-07). After Georgia Power 

chlorinates the water, it supplies to the Facility but performs no additional water treatment. The Facility 

receives the water in its raw water storage tank; a portion of the water is demineralized via reverse 

osmosis and transferred to the demineralized water tank prior to use. 

The Facility discharges cooling tower blowdown water into the Wansley Retention Pond. This is a batch 

process occurring approximately once per week. The Facility monitors the chlorine content of the 

blowdown water before discharge to ensure it is below the detection limit. The Facility adds sodium 

bisulfite, as needed, to dechlorinate the water. The Facility also discharges low volume wastewater 

(LVWW), consisting of water collected from indoor building drains and storm water collected from 

secondary containment areas, to the Wansley Retention Pond multiple times per day. The collected 

LVWW is sent through the Facility’s oil/water separator, and the pH may be adjusted, as needed, prior to 

discharge to the Wansley Retention Pond. Georgia Power discharges water from the Wansley Retention 

Pond to the Chattahoochee River (under NPDES Permit No. GA0026778). Oglethorpe is responsible for 

ensuring that cooling tower blowdown water meets the applicable limits for “Unit 8” in Georgia Power’s 

NPDES permit before discharging it to the Wansley Retention Pond. 

Potable water for use by site personnel (e.g., in kitchens, bathrooms) is purchased from the Heard County 

Water Authority. There is no on-site water treatment plant for potable uses. 
 Affected Environment and Environmental Consequences 

Oglethorpe Power 3-11 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

3.9.3.2 Environmental Consequences 

The Project would result in increased water usage and discharge quantities. Additional raw water would 

be drawn from the Service Water Reservoir for treatment and use in the cooling towers, and there would 

be additional water discharged from the Facility to the Retention Pond and ultimately to the 

Chattahoochee River. The cooling tower water usage and discharge are modeled to increase in quantity 

but the quality of the industrial wastewater discharges will not change, and the Facility will continue to 

operate within the parameters of Georgia Power’s existing surface water withdrawal permits (State Water 

Quality Control Permit Nos. 074-1291-06 and 074-1291-07) and industrial water discharge permit 

(NPDES Permit No. GA0026778). The Project would not result in an increased potable water usage 

because there would not be an increase in personnel, and potable water is not used for any of the Facility 

generation operations. 

 Table 3.13-1 summarizes the daily cooling tower water usage and discharges in recent years and the 

modeled usage and discharge levels after Project implementation. 

Table 3.9-4: Daily Treated Wastewater Usage and Discharges (thousand gal) 

Year 

Daily Average 

Cooling Tower 

Water Use1

Daily Maximum 

Cooling Tower 

Water Use 

Daily Average 

Cooling Tower 

Water Discharge1

Daily Maximum 

Cooling Tower 

Water Discharge2

2015 880 1,765 106 418 

2016 966 1,823 102 503 

2017 1,134 1,753 169 453 

2018 878 1,719 102 419 

2019 993 1,707 98 368 

Post TPU1 1,074 1,950 135 503 

1. Daily average water use and discharge for the cooling tower are based on the actual annual numbers 

divided by the number of days in the year. 

2. The cooling tower blowdown is discharged in a batch process occurring approximately once per week. 

The maximum quantity of blowdown water that can be discharged in a given day is limited by the 

discharge system, which would not be modified as part of the TPU1 project. As such, while the project 

may result in increases in the length of time to complete each discharge batch, it would not increase the 

maximum amount that can be discharged in a single 24-hour period. 

Source: Chattahoochee Energy Facility Discharge Monitoring Reports, Chattahoochee Energy Facility 

Water Use Calculations 

The estimated increase of approximately 243 thousand gallons of daily maximum cooling tower water 

usage would be within the parameters of Georgia Power’s withdrawal permits for Plant Wansley, which 

allow for 116 million gallons per day (MGD) from the Chattahoochee River to fill the Service Water 

Reservoir (Permit No. 074-1291-06) and 110.0 MGD from the Service Water Reservoir for use as cooling 

tower make-up water and general service water (Permit No. 074-1291-07). 
 Affected Environment and Environmental Consequences 

Oglethorpe Power 3-12 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

3.9.4 Mitigation 

Georgia Power’s industrial wastewater discharge NPDES permit will likely not require modification 

because the effluent composition will remain unchanged and the permit does not specify allowable 

discharge volumes for the Chattahoochee Energy Facility. Additionally, the Project would have increased 

daily water usage but the amounts would be within the parameters of Georgia Power’s existing surface 

water withdrawal permit. Therefore, there are no mitigation measures for the increased discharges or 

withdraws. 

Georgia Power’s industrial wastewater discharge NPDES permit will likely not require modification 

because the effluent composition will remain unchanged and the permit does not specify allowable 

discharge volumes for the Chattahoochee Energy Facility. Additionally, the Facility’s daily water usage 

following implementation of the Project will remain within the parameters of Georgia Power’s existing 

permit. Therefore, there are no mitigation measures for the increased discharge or withdrawal amounts. 

3.10 Threatened and Endangered Species 

Table 3.10-1 provides a list of state and federally protected species with the potential to occur in Carroll 

and Heard Counties. Protected species information for the specific Project Site was obtained from the 

U.S. Fish and Wildlife Service (FWS) Information for Planning, & Consultation System (IPaC). Any 

impacts from the Project would be limited to the existing Facility boundaries. There is no known habitat 

or previous occurrences documented for federal or state protected species within the Facility footprint, as 

documented in the IPaC documentation attached in Appendix D. Further, there is no designated critical 

habitat for protected species within the area (FWS, 2020). 

Table 3.10-1: Protected Species Potentially occurring in Carroll and Heard Counties 

Common Name Scientific Name County 

Federal 

Status 

State 

Status 

Mammals 

Gray bat Myotis grisescens Carroll E SE 

Indiana bat Myotis sodalis Carroll E - 

Northern long-eared bat Myotis septentrionalis Carroll T ST 

Clams 

Finelined pocketbook Lampsilis altilis Carroll T - 

Plants 

Little amphianthus Amphianthus pusillus Carroll; Heard E ST 

White-fringless orchid Platanthera integrilabia Carroll T ST 

Black-spored quillwort Isoetes melanospora Carroll; Heard E 
 Affected Environment and Environmental Consequences 

Oglethorpe Power 3-13 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

Source: FWS, 2020 

E= federally endangered, T = federally threatened, SE = state endangered, ST = state threatened

There are currently 30 state-protected species of plants and animals with potential to occur in Carroll and 

Heard Counties (GDNR, 2020). The Facility is located within the Chattahoochee River watershed, which 

is a state high priority watershed, and several federally protected species have been documented in the 

river. As the Project would involve only software and mechanical upgrades inside the Facility there will 

be no new ground disturbing impacts or clearing of vegetation. 

As discussed in Section 3.9, the cooling tower water usage and discharge are modeled to increase in 

quantity once the Project as implemented. However, as demonstrated in Table 3.13-1, there would not be 

a significant increase in water usage and discharges. the discharges would continue in batches and there 

would not be a significant change to the discharge volumes. The quality of the industrial wastewater 

discharges to the Chattahoochee River will also not change. The Facility will continue to operate within 

the parameters of Georgia Power’s existing surface water withdrawal permits (State Water Quality 

Control Permit Nos. 074-1291-06 and 074-1291-07) and industrial water discharge permit (NPDES 

Permit No. GA0026778). As a result, adverse impacts to aquatic species are not anticipated. Additionally, 

no protected species or critical habitat were identified for the Project Site in the IPaC report (Appendix 

D), and further consultation with FWS is not required. 

For these reasons, the proposed Project would have no effect on listed threatened or endangered species 

or their critical habitat. Therefore, in accordance with 1970.657(b) no further consultation with USFWS is 

required and the Section 7 review is complete. Since no impacts are anticipated, no special mitigation for 

protected species is proposed. 

3.11 Transportation 

Since the upgrades for the Project would occur during a routine major outage, there would already be a 

temporary increase in traffic at the Facility, and impacts from additional personnel and equipment to 

install the Project equipment would be negligible. No additional full-time employees would be hired for 

operation of Facility due to the Project, so there are no permanent traffic impacts anticipated. Therefore, 

no mitigation is proposed. 

3.12 Vegetation 

The Project would not require clearing of vegetation, as all control and mechanical adjustments would 

occur within the existing Facility. Therefore, no mitigation is proposed. 
 Affected Environment and Environmental Consequences 

Oglethorpe Power 3-14 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

3.13 Water Resources and Wetlands 

There are no wetlands or waterbodies within the boundaries of the Facility. A National Wetlands 

Inventory map is included in Appendix E. There is one perennial stream and one emergent wetland on 

the Plant Wansley property, associated with the Retention Pond that acts as the receiving body for the 

blowdown water from the Facility. The pond discharges into the Chattahoochee River, and the Facility is 

located in the “Chattahoochee River Lower North 6” watershed which is considered high priority by the 

Georgia Department of Natural Resources. For the proposed Project, all control and mechanical 

adjustments would occur within existing Facility structures and would not result in any new impacts to 

the receiving waters or associated wetland. 

There would be no ground-disturbing impacts as a result of the Project. The impacts of the Project on 

water withdrawn from and discharged to the Chattahoochee River, discussed in section 3.9, will be 

minimal. Therefore, no impacts on water resources and wetlands are anticipated, and no mitigation is 

proposed. 

3.14 Wildlife 

The Plant Wansley property is entirely fenced for security purposes. The existing fence is approximately 

eight feet high, which deters wildlife from entering the Facility. No changes to the existing Facility 

footprint or fence line are proposed. Therefore, no impacts on wildlife are anticipated.
 Cumulative Effects 

Oglethorpe Power 4-1 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

4.0 CUMULATIVE EFFECTS 

As defined by the CEQ, a cumulative effect is the impact on the environment that results from the 

incremental impact of the proposed action when added to other past, present, or reasonably foreseeable 

future actions, regardless of what agency or person undertakes such other actions (CEQ, 1997). Although 

the individual impact of each separate project may be minor, the additive or synergistic effects of multiple 

projects could be significant. 

In order to understand the contribution of past actions to the cumulative impacts of the proposed action, 

this analysis relies on current environmental conditions as a proxy for the impacts of past actions. This is 

because existing conditions reflect the aggregate impact of all prior human actions and natural events that 

have affected the environment and might contribute to cumulative effects. In this analysis, RUS has 

generally considered the impacts of past projects within the resource-specific geographic scopes as part of 

the affected environment (environmental baseline), which was described under the specific resources 

discussed throughout section 3.0. This cumulative impact analysis includes other actions meeting the 

following three criteria: 

 the action impacts a resource that is also potentially affected by the Facility’s TPU1 upgrade and 

LLTD upgrade Project; 

 the action causes the impacts within all or part of the same geographic scope as the Facility’s 

TPU1 upgrade and LLTD upgrade Project; and 

 the action causes this impact within all or part of the temporal scope for the potential impacts 

from the Facility’s TPU1 upgrade and LLTD upgrade Project. 

Based on the previous findings discussed throughout Section 3.0, the Project would only result in impacts 

on air quality and water use. Therefore, when combined with other past, present, and reasonably 

foreseeable future project, the Facility’s planned Project could only contribute to cumulative impacts on 

air quality and water use. For the Project to contribute towards a cumulative impact on air quality and/or 

water use, the other contributing project(s) must overlap the same geographic and temporal scope as the 

planned Project. 

For air quality, the distance used to establish a geographic scope was derived from the EPA’s cumulative 

modeling of large PSD sources during permitting and follows 40 CFR 51, Appendix W, Section 4.1. This 

references a 31-mile (50-kilometer) radius of current or proposed sources of operational emissions. 

Although PSD modeling was not performed for this Project, if there is another ongoing or proposed 
 Cumulative Effects 

Oglethorpe Power 4-2 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

emission source within the Facility’s 31-mile radius, a cumulative impact could occur when the other 

project(s) is combined with the Project. 

Oglethorpe is unaware of any newly proposed or pending power generating facilities within a 31-mile 

radius. Other proposed or pending non-energy projects identified within the same geographic scope as the 

proposed Project include: 

 General residential, commercial, and manufacturing/industrial development and construction; 

 New and existing roadway construction and maintenance; 

 Expansion of the Carroll County regional airport; and 

 Landfills currently operating under a Title V permit. 

4.1 Cumulative Impacts by Resource 

4.1.1 Aesthetics 

The Project would not result in an impact to current surrounding aesthetics and also would not contribute 

towards a cumulative impact on aesthetics. 

4.1.2 Air Quality 

Oglethorpe is not aware of any planned projects for other sources located near the Facility for which the 

Project would have a cumulative impact on air quality. Any other projects near the Facility would need to 

evaluate on a case-by-case basis whether cumulative modeling is required under the PSD regulations to 

demonstrate no violations of the NAAQS or PSD Increment will occur. Should such modeling be 

required in the future, the other projects and sources would include the Facility’s post-Project potential 

emissions in its cumulative modeling evaluation. 

4.1.3 Floodplains 

As discussed in Section 3.3 and shown in Appendix C, the Project will not be located in a floodplain. 

The Project would not result in floodplain impacts and would not contribute towards a cumulative impact 

on floodplains.

4.1.4 Geology, Soils, and Farmland 

The Project would not result in geology, soils, or farmland impacts and would not contribute towards a 

cumulative impact on geology, soils, or farmland. 
 Cumulative Effects 

Oglethorpe Power 4-3 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

4.1.5 Historical and Cultural Resources 

The Project would not result in a historical or cultural resources impact on existing resources and would 

not contribute towards a cumulative impact on historical, cultural, or archeological resources. 

4.1.6 Human Health and Safety 

The Project would not result in adverse impacts to human health and safety and would not contribute 

towards a cumulative impact on human health and safety. 

4.1.7 Land Use 

The Project would not result in an impact to current land use types and would not contribute towards a 

cumulative impact on land use. 

4.1.8 Noise 

The Project would not result in an increase in noise levels above historical levels and would not 

contribute towards a cumulative impact on noise levels at NSAs. 

4.1.9 Socioeconomics and Environmental Justice 

The Project would not result in an adverse impact on the existing socioeconomic conditions of the area or 

any environmental justice communities and also would not contribute towards an adverse cumulative 

impact on socioeconomics or environmental justice. 

The Project would not result in any adverse impacts to potable water, sanitary sewer, electricity, gas, or 

solid waste services. The Facility withdraws and discharges to and from the Chattahoochee River under 

Georgia Power’s permits for the Wansley Plant. For the industrial water discharges from the Facility, 

water composition will remain unchanged and the industrial discharge water permit does not specify 

allowable discharge volumes. The Project would result in an increase in daily water usage, but the 

amounts would be within the parameters of Georgia Power’s water withdrawal permits. Therefore, there 

would be no changes to Georgia Power’s NPDES discharge permit or withdrawal permits. Further, 

Oglethorpe is unaware of any other proposed or pending projects that will be withdrawing or discharging 

water to/from the Chattahoochee River in the vicinity of the Project. Therefore, the proposed Project is 

unlikely to contribute to an adverse cumulative impact on utilities. 

4.1.10 Threatened and Endangered Species 

The Project will have no effect on federally or state protected species and water withdrawals and 

discharges to and from the Chattahoochee River would not significantly change and would continue 
 Cumulative Effects 

Oglethorpe Power 4-4 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

within the parameters of the permits. Therefore, the Project would not contribute towards a cumulative 

impact on protected species. 

4.1.11 Transportation 

The Project would not adversely affect transportation and would not contribute towards a cumulative 

impact on traffic or transportation when combined with other past, present, or reasonably foreseeable 

future projects. 

4.1.12 Vegetation 

The Project would not require clearing of vegetation or any soil disturbance and would not contribute 

towards an adverse cumulative impact on existing vegetation. 

4.1.13 Water Resources and Wetlands 

The Project would not affect wetlands or waterbodies and water withdrawals and discharges to and from 

the Chattahoochee River would not significantly change and would continue within the parameters of the 

permits. Therefore, the Project would not contribute towards a cumulative impact on water resources and 

wetlands. 

4.1.14 Wildlife 

The Project would not result in an impact on wildlife and would not contribute towards a cumulative 

impact on wildlife. 
Summary of Mitigation 

Oglethorpe Power 5-1 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

5.0 SUMMARY OF MITIGATION 

No resources would be adversely impacted by the Project, and therefore no mitigation efforts are 

proposed. The Facility would continue proper operation of air emission controls such as dry low NOX

combustors on the turbines and low NOX duct burners, SCR, catalytic oxidation, and the use of low-sulfur 

fuel, as required by the existing air permit. 
 Public Involvement 

Oglethorpe Power 6-1 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

6.0 PUBLIC INVOLVEMENT 

This EA will be made available to the public for a 14-day public review and comment period. Availability 

of the document for review and comment will be noticed in a local newspaper. Copies of the EA will be 

made available for public review at RUS, 1400 Independence Avenue, SW, Washington DC 20250-3201; 

at the headquarters of Oglethorpe at 2100 E Exchange Pl., Tucker, GA 30084; and at the Heard County 

Public Library at 564 Main Street, Franklin, GA 30217. 

All comments from reviewers should be addressed to: 

Dennis Rankin 

U.S. Dept. of Agriculture, Rural Utilities Service 

1400 Independence Avenue, SW, Washington DC 20250-3201 

dennis.rankin@usda.gov 

Once RUS has reviewed comments, it will issue its environmental decision related to the Project. Should 

RUS choose to issue a Finding of No Significant Impact (FONSI) for the Project, a newspaper notice will 

be published informing the public of the RUS finding and the availability of the EA and FONSI. The 

notice shall be prepared in accordance with RUS guidance. 
List of Preparers 

Oglethorpe Power 7-1 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

7.0 LIST OF PREPARERS 

The EA for the Project was prepared by RUS in coordination with Oglethorpe Power Corporation, Inc. 

and Burns & McDonnell. The following is a list of preparers of this document. 

RUS 

 Lauren Rayburn, Environmental Scientist, Engineering and Environmental Staff 

 Kenneth Solano, Engineering Branch Chief, Office of Loan Original and Approval 

Oglethorpe 

 Don Cheatham, Project Manager 

 Dan Neumann, Chattahoochee Energy Facility Operations Manager 

 John Miller, Chattahoochee Energy Facility Plant Manager 

 Courtney Adcock, Senior Environmental Specialist 

 Toni Presnell, Vice President Environmental Affairs 

Burns & McDonnell 

 Sara Kent, Project Manager 

 Steve Thornhill, NEPA Manager 

 Jesse A Brown, Senior Environmental Scientist 

 Bruce Battle, Staff Environmental Scientist 

 Emily Robbins, Staff Environmental Engineer 
 References 

Oglethorpe Power 8-1 Chattahoochee Energy Facility 

Combustion Turbine Upgrades Project 

8.0 REFERENCES 

Council on Environmental Quality (CEQ). 1997. Environmental Justice Guidance under the National 

Environmental Policy Act. Executive Office of the President, Washington, DC. 

Georgia Department of Natural Resources (GDNR). 2020. Georgia Biodiversity Portal. Heard County & 

Carroll County. Accessed on April 13, 2020. Available from 

https://www.georgiabiodiversity.a2hosted.com/natels/elementmap?area=cnty&group=all_groups

U.S. Code (USC). 2020. Accessed via the internet on May 8, 2020 at: https://uscode.house.gov/

U.S. Environmental Protection Agency (EPA). 2020a. NAAQS Table. Accessed via the internet on May 

7, 2020 at: https://www.epa.gov/criteria-air-pollutants/naaqs-table. 

U.S. Environmental Protection Agency (EPA). 2020b. EJSCREEN: Environmental Justice Screening and 

Mapping Tool. Retrieved 25 September 2020 from https://www.epa.gov/ejscreen.

U.S. Fish and Wildlife Service (FWS). 2020. List of threatened and endangered species that may occur in 

your proposed project location, and/or may be affected by your project. Consultation Code: 

04EG1000-2020-SLI-1928. Event code: 04EG1000-2020-E-03553. Letter issued on April 12, 2020. 
APPENDIX A - MEMO ADDRESSING IMPACTS TO CULTURAL RESOURCES 
USDA is an equal opportunity provider and employer. 

If you wish to file a Civil Rights program complaint of discrimination, complete the USDA Program Discrimination Complaint Form, found 

online at http://www.ascr.usda.gov/complaint_filing_cust.html, or at any USDA office, or call (866) 632-9992 to request the form. You may 

also write a letter containing all of the information requested in the form. Send your completed complaint form or letter to us by mail at 

U.S. Department of Agriculture, Director, Office of Adjudication, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410, by fax 

(202) 690-7442 or email at program.intake@usda.gov. 

Rural Development

Rural Utilities Service

Water and 

Environmental 

Programs

Engineering and 

Environmental Staff

INTRAOFFICE MEMORANDUM

DATE: September 8, 2020

SUBJECT: GA 109, Oglethorpe Power Corporation

Chattahoochee Energy Facility, Environmental Assessment 

No Potential to Effect Historic Properties under Section 106 

of the National Historic Preservation Act

TO: ERIKA MARTIN SEIBERT

Federal Preservation Officer

Rural Utilities Service (RUS)

FROM: LAUREN RAYBURN

Physical Scientist (Environmental) 

EES, WEP, RUS

The proposed Project would involve the implementation of two upgrades for the 

Chattahoochee Energy Facility’s two combustion turbines: the Thermal Performance 

Upgrade Step 1 (TPU1) and the Low Load Turndown (LLTD) upgrade. In performing 

these upgrades, the cooperative has indicated that software and mechanical upgrades to 

existing equipment within the current Facility structures would be required. The project 

would not involve new ground disturbance (see Attachment 1: Project Location Map). 

Because of the lack of ground disturbance or modifications to the appearance of the 

facility, the proposed undertaking would not result in a change to ground features or 

visual elements of the landscape. Accordingly, I recommend use of 36 CFR 

§800.3(a)(1) for this potential undertaking1. 

DECISION BY FEDERAL PRESERVATION OFFICER

 

Concur 

___________ Discuss

9/8/2020 Date

 

1 36 CFR §800.3(a)(1): No potential to cause effects. If the undertaking is a type of activity that does not 

have the potential to cause effects on historic properties, assuming such historic properties were present, 

the agency official has no further obligations under section 106 or this part.
2 

Attachment 1: Project Location Map
APPENDIX B – TITLE V SIGNIFICANT MODIFICATION WITH CONSTRUCTION 

APPLICATION 
TITLE V SIGNIFICANT MODIFICATION 

WITH CONSTRUCTION APPLICATION

Oglethorpe Power Corporation > Chattahoochee Energy 

Facility

TRINITY CONSULTANTS

3495 Piedmont Road

Building 10, Suite 905

Atlanta, GA 30305

(678) 441-9977

June 2020

Project 201101.0056
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TABLE OF CONTENTS

1. EXECUTIVE SUMMARY 1-1

1.1 Proposed Project Description ..................................................................................... 1-1

1.2 Permitting and Regulatory Requirements .................................................................. 1-1

1.3 Application Contents................................................................................................... 1-2

2. PROPOSED PROJECT DESCRIPTION 2-1

3. EMISSIONS CALCULATION METHODOLOGY 3-1

3.1 NSR Permitting Evaluation Methodology.................................................................... 3-1

3.2 Defining Existing Versus New Emission Units............................................................. 3-2

3.3 Annual Emissions Increase Calculation Methodology................................................. 3-2

3.3.1 Potential Emissions ................................................................................................... 3-3

3.3.2 Baseline Actual Emissions .......................................................................................... 3-4

3.3.3 Projected Actual Emissions ........................................................................................ 3-4

3.3.4 Could Have Accommodated Emissions........................................................................ 3-4

3.3.5 Additional Associated Emission Unit Increases............................................................. 3-5

3.4 Baseline Actual Emissions........................................................................................... 3-5

3.5 Projected Actual Emissions......................................................................................... 3-5

3.6 Could Have Accommodated Emissions........................................................................ 3-7

3.7 NSR Emissions Increase Summary ............................................................................. 3-7

3.8 Potential Emissions Estimate...................................................................................... 3-8

3.8.1 Combined Cycle Combustion Turbines ........................................................................ 3-8

3.8.2 HAP/TAP Emissions................................................................................................. 3-10

3.8.3 Cooling Tower ........................................................................................................ 3-10

3.8.4 Insignificant Emissions Sources................................................................................ 3-10

4. REGULATORY APPLICABILITY ANALYSIS 4-1

4.1 New Source Review Applicability................................................................................ 4-1

4.2 Title V Operating Permits............................................................................................ 4-2

4.3 New Source Performance Standards .......................................................................... 4-2

4.3.1 40 CFR 60 Subpart A – General Provisions .................................................................. 4-3

4.3.2 40 CFR 60 Subpart D – Fossil Fuel-Fired Steam Generators > 250 MMBtu/hr................. 4-3

4.3.3 40 CFR 60 Subpart Da – Electric Utility Steam Generating Units ................................... 4-3

4.3.4 40 CFR 60 Subpart Db – Steam Generating Units > 100 MMBtu/hr............................... 4-4

4.3.5 40 CFR 60 Subpart Dc – Small Steam Generating Units................................................ 4-4

4.3.6 40 CFR 60 Subpart GG – Stationary Gas Turbines........................................................ 4-5

4.3.7 40 CFR 60 Subpart KKKK – Stationary Combustion Turbines ........................................ 4-5

4.3.8 40 CFR 60 Subpart TTTT – Greenhouse Gas Emissions for Electric Generating Units ...... 4-7

4.3.9 Non-Applicability of All Other NSPS ............................................................................ 4-8

4.4 National Emission Standards for Hazardous Air Pollutants ........................................ 4-8

4.4.1 40 CFR 63 Subpart A – General Provisions .................................................................. 4-8

4.4.2 40 CFR 63 Subpart YYYY – Combustion Turbines ........................................................ 4-8

4.4.3 40 CFR 63 Subpart DDDDD – Industrial, Commercial, and Institutional Boilers and Process 

Heaters............................................................................................................................... 4-9

4.4.4 40 CFR 63 Subpart UUUUU – Electric Utility Steam Generating Units........................... 4-10

4.4.5 40 CFR 63 Subpart JJJJJJ – Industrial, Commercial, and Institutional Boilers at Area 

Sources ............................................................................................................................ 4-10
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4.4.6 Non-Applicability of All Other NESHAP ...................................................................... 4-10

4.5 Compliance Assurance Monitoring............................................................................4-10

4.6 Risk Management Plan .............................................................................................4-11

4.7 Stratospheric Ozone Protection................................................................................4-11

4.8 Clean Air Markets Regulations..................................................................................4-11

4.8.1 Acid Rain Program .................................................................................................. 4-11

4.8.2 Clean Air Interstate Rule / Cross-State Air Pollution Rule............................................ 4-12

4.9 State Regulatory Requirements................................................................................4-12

4.9.1 GRAQC 391-3-1-.02(2)(b) – Visible Emissions ........................................................... 4-13

4.9.2 GRAQC 391-3-1-.02(2)(d) – Fuel-Burning Equipment................................................. 4-13

4.9.3 GRAQC 391-3-1-.02(2)(e) – Particulate Emissions from Manufacturing Processes ........ 4-14

4.9.4 GRAQC 391-3-1-.02(2)(g) – Sulfur Dioxide ............................................................... 4-14

4.9.5 GRAQC 391-3-1-.02(2)(n) – Fugitive Dust................................................................. 4-14

4.9.6 GRAQC 391-3-1-.02(2)(tt) – VOC Emissions from Major Sources ................................ 4-14

4.9.7 GRAQC 391-3-1-.02(2)(uu) – Visibility Protection ...................................................... 4-14

4.9.8 GRAQC 391-3-1-.02(2)(jjj) – NOX from Electric Utility Steam Generating Units............. 4-14

4.9.9 GRAQC 391-3-1-.02(2)(lll) – NOX from Fuel-Burning Equipment ................................. 4-15

4.9.10 GRAQC 391-3-1-.02(2)(mmm) – NOX Emissions from Stationary Gas Turbines and 

Stationary Engines used to Generate Electricity.................................................................... 4-15

4.9.11 GRAQC 391-3-1-.02(2)(nnn) – NOX Emissions from Large Stationary Gas Turbines ...... 4-15

4.9.12 GRAQC 391-3-1-.02(2)(rrr) – NOX from Small Fuel-Burning Equipment ....................... 4-15

4.9.13 GRAQC 391-3-1-.02(2)(sss) – Multipollutant Control for Electric Utility Steam Generating 

Units 4-15

4.9.14 GRAQC 391-3-1-.02(2)(uuu) – SO2 Emissions from Electric Utility Steam Generating Units ..

4-16

4.9.15 GRAQC 391-3-1-.03(1) – Construction (SIP) Permitting ............................................. 4-16

4.9.16 GRAQC 391-3-1-.03(10) – Title V Operating Permits.................................................. 4-16

4.9.17 Incorporation of Federal Regulations by Reference.................................................... 4-16

4.9.18 Non-Applicability of Other GRAQC ............................................................................ 4-16

5. TOXICS IMPACT ANALYSIS 5-1

5.1 Derivation of Facility-Wide Emission Rates ................................................................ 5-1

5.2 Determination of Toxic Air Pollutant Impact .............................................................. 5-2

APPENDIX A. AREA MAP AND PROCESS FLOW DIAGRAM A-1

APPENDIX B. EMISSION CALCULATIONS B-1

APPENDIX C. TOXICS IMPACT ANALYSIS DOCUMENTATION C-1

APPENDIX D. EPD SIP FORMS D-1
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LIST OF TABLES

Table 1-1. Proposed Project Emissions Increases 1-2

Table 3-1. Criteria Pollutant Projected Actual Emission Factors for CCCT Units 3-6

Table 3-2. Project Emissions Increase 3-8

Table 3-3. Criteria Pollutant Emission Factors for CCCT Units 3-9

Table 4-1. Project Emission Increases Compared to PSD and NNSR SERs 4-2

Table 5-1. OPC Chattahoochee TAP Emissions and Respective MERs 5-2

Table 5-2. Stack Parameters 5-2

Table 5-3. SCREEN3 Modeling Results at 1 g/s 5-3

Table 5-4. Modeling Results Compared to AAC Values 5-4
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1. EXECUTIVE SUMMARY

Oglethorpe Power Corporation (OPC) owns and operates a gas-fired electrical power plant near Franklin, 

Georgia in Heard County, known as the Chattahoochee Energy Facility (OPC Chattahoochee). OPC 

Chattahoochee is a major source under both the Title V operating permit program and the Prevention of 

Significant Deterioration (PSD) construction permitting program. This facility currently operates under Part 

70 Operating Permit No. 4911-149-0006-V-05-0, effective January 30, 2018, issued by the Georgia 

Environmental Protection Division (EPD).

OPC Chattahoochee is a natural gas-fired combined-cycle facility presently capable of producing a nominal 

power output of 526 megawatts (MW). The facility operates one power block consisting of two combined 

cycle combustion turbines (CCCTs) and one steam turbine, referred to as a “2-on-1” configuration. Each 

CCCT includes a Siemens-Westinghouse Model V84.3A2 combustion turbine (CT) exhausting to a heat 

recovery steam generator (HRSG), which generates steam to power the block’s steam turbine. Each HRSG 

has a duct burner (DB) to provide supplementary firing for additional steam generation as needed.

To minimize the formation of oxides of nitrogen (NOX), each CT is equipped with dry low NOX combustors 

and each duct burner with low NOX burners. In addition, each CT and associated duct burner stack is 

equipped with catalytic oxidation to control emissions of carbon monoxide (CO) and volatile organic 

compounds (VOC) and with a selective catalytic reduction (SCR) system to control NOX emissions.

OPC Chattahoochee’s proposed CT Upgrades Project would increase the current generation capacity of the 

facility, helping to reduce the overall cost per megawatts (MW) of power generated, and would allow the 

facility’s gas turbines to continue to operate at reduced power during times of low demand with less 

frequent shutdowns and subsequent restarts once demand increases. The project would result in increases 

in maximum heat input and maximum projected annual air emissions. This application package contains the 

necessary state air construction and operating permit submittals for the proposed project. This application is 

being submitted using the Georgia EPD Online System (GEOS) with application ID No. 486572.

1.1 Proposed Project Description

The proposed CT Upgrades Project would involve the implementation of two upgrades for OPC 

Chattahoochee’s two combustion turbines: the Thermal Performance Upgrade One (TPU1) and the Low 

Load Turndown (LLTD) upgrade.

The TPU1 would improve the combustion turbines, plant output, and heat rate as well as extend the 

maintenance interval of the units by installing enhanced hardware in the combustion turbines, replacing 

certain auxiliary hardware components, and adding site-specific control logic optimizations.

The LLTD upgrade would involve the installation of new combustion turbine components and software 

controls to replace selected equipment and connected accessories to allow for sustained operations at lower 

operating loads during periods of low demand.

1.2 Permitting and Regulatory Requirements

OPC is submitting this construction and operating permit application to request authorization to modify and 

operate the facility’s CTs. Since OPC Chattahoochee is a major source under the PSD permitting program, 

emission increases from the proposed project must be evaluated and compared to the significant emission 
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rates (SERs) for regulated pollutants under the PSD program. OPC has evaluated emissions increases of CO, 

NOX, particulate matter (PM), total particulate matter with an aerodynamic diameter of less than 10 

microns (PM10), total particulate matter with an aerodynamic diameter of less than 2.5 microns (PM2.5), 

greenhouse gases (GHG) in terms of carbon dioxide equivalents (CO2e), sulfur dioxide (SO2), sulfuric acid 

mist (H2SO4), and VOC resulting from the proposed project for comparison to their respective PSD SERs to 

determine whether PSD permitting is required, as shown in Table 1-1.

1

Table 1-1. Proposed Project Emissions Increases

Since the combined project emissions increases of all pollutants are below their respective SERs, the 

proposed project is not required to undergo PSD review. Emission calculations are described in Section 3 of 

this application, and New Source Review (NSR) applicability is detailed in Section 4.1.

OPC is submitting this construction and operating permit application package in accordance with all federal 

and state requirements. The proposed project will be subject to federal New Source Performance Standards 

(NSPS) and the Georgia Rules for Air Quality Control (GRAQC). Applicability of these programs is discussed 

in Section 4 of this application.

1.3 Application Contents

► Section 2 contains a description of the proposed project;

► Section 3 summarizes emissions calculation methodologies and assesses PSD applicability;

► Section 4 details the regulatory applicability analysis for the proposed project;

► Section 5 contains the toxics impact assessment;

► Appendix A includes an area map and simplified process flow diagram; 

► Appendix B includes detailed emission calculations;

► Appendix C contains documentation for the toxics impact analysis; and

► Appendix D contains the EPD SIP construction permit application forms.

1 AP-42, Chapter 3, Section 1, Stationary Gas Turbines, lists the lead (Pb) emission factor for natural gas turbines as ND (no 

detect); therefore, Pb emissions increases for the proposed project were not evaluated.

Baseline 

Actual 

Emissions

(tpy)

"Could Have 

Accommodated" 

Emissions

(tpy)

Projected 

Actual 

Emissions

(tpy)

Project 

Emissions 

Increase1

(tpy)

NOX 100.2 116.4 153.1 36.7 - 36.7 40 No

CO 19.0 30.0 67.6 37.6 - 37.6 100 No

VOC 11.6 13.5 15.1 1.59 - 1.6 40 No

PM 69.7 81.1 90.6 9.5 0.31 9.8 25 No

PM1 0 69.7 81.1 90.6 9.5 0.27 9.8 15 No

PM2.5 69.7 81.1 90.6 9.5 1.5E-03 9.5 10 No

SO2 7.0 8.1 9.1 0.95 - 0.9 40 No

H2SO4 0.80 0.93 1.0 0.11 - 0.1 7 No

CO2e

3 1,382,762 1,608,206 1,796,567 188,361 - 188,361 75,000 No

2. 40 CFR 52.21(b)23(i) and Georgia Air Quality Control Rule 391-3-1-.03(8)(c)15

1. Project Emissions Increase = (Projected Actual Emissions - Baseline Actual Emissions) - ("Could Have Accommodated" Emissions - Baseline Actual Emissions)

3. NSR permitting for CO2e is only required if the project emissions increase exceeds the NSR SER of 75,000 tpy and if NSR permitting is triggered for at least one other 

regulated pollutant.

Pollutant

Units 8A and 8B Cooling 

Tower 

Associated 

Emissions 

Increase

(tpy)

NSR 

Significant 

Emission 

Rate2

(tpy)

NSR 

Triggered?

Total 

Project 

Emissions 

Increase

(tpy)
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2. PROPOSED PROJECT DESCRIPTION

The proposed CT Upgrades Project would involve the implementation of two upgrades for OPC 

Chattahoochee’s two combustion turbines: the TPU1 and the LLTD upgrade. 

The TPU1 would improve the combustion turbines, plant output, and heat rate as well as extend the 

maintenance interval of the units by installing enhanced hardware in the combustion turbines, replacing 

certain auxiliary hardware components, and adding site-specific control logic optimizations. New turbine 

hardware would include combustion chamber components with optimized cooling air reduction, 

impingement cooled tile holders, the latest ceramic heat shields, metallic heat shields, and burner swirlers 

with reduced swirl angle. Auxiliary hardware replacements would include the pilot gas flow meter, an 

advanced combustion dynamics monitoring system, heat resistant ignition cables, blow-off valve actuators, 

and additional pressure and acceleration measurement instrumentation. These changes would increase the 

capacity of the facility by approximately 23 MW, with variations for ambient temperatures. The increased 

capacity would decrease the cost of electricity generation.

The LLTD upgrade would involve the installation of new combustion turbine components and software 

controls to replace selected equipment and connected accessories to allow for sustained operations at lower 

operating loads during periods of low demand. These changes would include the compressor inlet guide 

vane extended range sensor, ring modification and linearization unit replacement, and the addition of a 

combustion turbine exhaust metallic heat shield, along with site-specific control logic optimizations. 

Currently, the facility shuts down periodically during low demand and then restarts when demand increases. 

The LLTD upgrades would allow the combustion turbines to operate at steady-state minimum loads of 

approximately 67 MW, with variations for ambient temperatures, while continuing to maintain emission 

concentrations of NOX and CO in compliance with the facility’s permitted emission limits. As a result, this 

upgrade would allow the facility to continue to operate with less frequent shutdowns during low demand 

periods, thereby reducing maintenance and fuel costs associated with cycling through shutdowns and 

startups.
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3. EMISSIONS CALCULATION METHODOLOGY

This section addresses the methodology used to quantify the emissions from the proposed project and 

assesses federal NSR permitting applicability. Pollutants with an emissions increase from the proposed 

project include CO, NOX, SO2, VOC, PM, PM10, PM2.5, H2SO4, GHG in the form of CO2e, and hazardous air 

pollutants (HAP). These emissions occur as a result of natural gas combustion in the combustion turbines 

and duct burners. Detailed emission calculations are presented in Appendix B.

3.1 NSR Permitting Evaluation Methodology

The NSR permitting program generally requires that a source obtain a permit prior to construction of any 

project at an industrial facility if the proposed project results in increases in air pollution emissions in excess 

of certain threshold levels. The federal NSR program is comprised of two elements: Nonattainment 

NSR (NNSR) and PSD. The NNSR program potentially applies to new construction or modifications that 

result in emission increases of a particular pollutant for which the area the facility is located in is classified 

as “nonattainment” with the National Ambient Air Quality Standards (NAAQS) for that pollutant. The PSD 

program applies to project increases of those pollutants for which the area the facility is located in is 

classified as “attainment” or “unclassifiable” for the NAAQS. OPC Chattahoochee is located in Heard County, 

which has been designated by the U.S. EPA as “attainment” or “unclassifiable” for all criteria pollutants.2

Therefore, PSD is the applicable permitting program under the federal NSR program. OPC Chattahoochee is 

an existing PSD major source, as it has potential emissions of multiple regulated criteria pollutants 

exceeding the major source threshold of 100 tpy.3 As a result, new construction or modifications that result 

in emissions increases for criteria pollutants are potentially subject to PSD permitting requirements.

Additionally, the facility is located in a county specified by the Georgia EPD as subject to GRAQC 391-3-1-

.03(8)(c)15, which addresses additional provisions for electrical generating units in the areas contributing to 

the Atlanta ozone nonattainment area. This state regulation specifies that certain NNSR provisions are 

potentially applicable when permitting new construction or modifications at any electrical generating unit 

that is located in a listed contributing county and that has facility-wide potential NOX emissions exceeding 

100 tpy.4 As OPC Chattahoochee’s potential NOX emissions exceed 100 tpy, the facility is a major source for 

NOX emissions under this state regulation. Therefore, applicability of the proposed project to these NNSR 

permitting provisions must be assessed. 

The following sections discuss the methodology used in the project emissions increase evaluation conducted 

to assess NSR applicability under the PSD and state NNSR program. As the facility is classified as a major 

source for PSD, if the proposed project meet the definition of a major modification, then the full PSD 

permitting requirements apply. For all PSD-regulated pollutants other than CO2e, PSD permitting is required 

if the emissions increase of a specific pollutant exceeds that pollutant’s PSD SER. For CO2e, PSD permitting 

is only required if the emissions increase exceeds the SER for CO2e and the project is already undergoing 

2 40 CFR 81.311

3 Fossil fuel-fired steam electric plants of more than 250 MMBtu/hr input (which includes combined cycle natural gas plants) 

are on the “List of 28” named source categories which are subject to a lower major source threshold for criteria pollutants of 

100 tpy.

4 GRAQC 391-3-1-.03(8)(c)15(i)
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PSD permitting for at least one other PSD-regulated pollutant.5 For NOX, certain NNSR provisions are 

required if the emissions increase exceeds the applicable NNSR SER of 40 tpy.6

3.2 Defining Existing Versus New Emission Units

For purposes of calculating project emissions increases, different calculation methodologies are used for 

existing and new units; therefore, it is important to clarify whether the sources affected by the proposed 

project are considered new or existing emission units. 

40 CFR 52.21(b)(7)(i) and (ii) define new unit and existing units, and are incorporated by reference in the 

GRAQC: 

(i) A new emissions unit is any emissions unit that is (or will be) newly constructed 

and that has existed for less than 2 years from the date such emissions unit first 

operated.

(ii) An existing emissions unit is any unit that does not meet the requirements in 

paragraph (b)(7)(i) of this section. A replacement unit, as defined in paragraph 

(b)(33) of this section, is an existing emissions unit.

As the emission units at OPC Chattahoochee have operated for more than two years, the proposed project 

involves physical or operational changes to existing emission units only – specifically, the facility’s 

combustion turbines. There are no new emission units proposed for installation as part of this project.

3.3 Annual Emissions Increase Calculation Methodology

As OPC Chattahoochee is classified as a major source for PSD, if the proposed project meets the definition 

of a major modification, then the full PSD permitting requirements apply. Major modification is defined by 

40 CFR 52.21(b)(2)(i):

“Major Modification” means any physical change in or change in the method of 

operation of a major stationary source that would result in a significant emission 

increase ... of a regulated NSR pollutant ... and a significant net emissions increase of 

that pollutant ... 

Certain exemptions to the major modification definition exist that, if applicable, means a project does not 

require an emission increase assessment. The proposed project does not qualify for any of the established 

exemptions.

The project emissions have been analyzed using the current NSR Reform methodology to determine if a 

significant emissions increase will occur. Net emissions increase (NEI) is defined by 40 CFR 52.21(b)(3)(i):

“Net Emissions Increase” means, with respect to any regulated NSR pollutant ... the 

amount by which the sum of the following exceeds zero:

5 40 CFR 52.21(b)(49)(iii) as incorporated by reference in the GRAQC 

6 GRAQC 391-3-1-.03(8)(c)15(ii)
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(a) The increase in emissions ... as calculated pursuant to paragraph (a)(2)(iv) [for 

existing units, calculated by actual-to-projected actual

7 or actual-to-potential; for 

new units, calculated by actual-to-potential]

8

(b) Any other increases or decreases in actual emissions...that are contemporaneous 

with the particular change and are otherwise creditable. Baseline emissions for 

calculating increases and decreases...shall be determined as provided...

The first step (1) is commonly referred to as the “project emission increases” as it has historically accounted 

only for emissions related to the proposed project itself. If the emission increases estimated per step (1) 

exceed the major modification thresholds, then the applicant may move to step (2), commonly referred to 

as the 5-year netting analysis. The netting analysis includes all projects for which emission increases or 

decreases (e.g., equipment shutdown) occurred. If the resulting net emission increases exceed the major 

modification threshold, then NSR permitting is required. OPC has evaluated the project emissions increase 

for the proposed project (i.e., Step 1) using the methodologies outlined in the following sections. An 

evaluation of the net emissions increase (i.e., Step 2) was neither required nor conducted for the proposed 

project. 

While the prior quotations only reference three components of the NEI calculation (actual, projected actual, 

and potential emissions), there are actually five calculated components, with the additional components 

being (1) a subset of the definition for projected actual and (2) additional associated emission unit 

increases:

► Potential emissions 

► Baseline actual emissions 

► Projected actual emissions 

► “Could have accommodated” emissions exclusion (commonly called the demand growth exclusion)

► Additional associated emission unit increases

3.3.1 Potential Emissions

Potential emissions are defined by 40 CFR 52.21(b)(4) where the potential to emit:

...means the maximum capacity of a stationary source to emit a pollutant under its 

physical and operational design. Any physical or operational limitation on the 

capacity of the source to emit a pollutant, including air pollution control equipment 

and restrictions on hours of operation or on the type or amount of material 

combusted, stored, or processed, shall be treated as part of its design if the 

limitation or the effect it would have on emissions is federally enforceable...

7 40 CFR 52.21(a)(2)(iv)(c), Actual-to-projected-actual applicability test for projects that only involve existing emissions units, 

states: A significant emissions increase of a regulated NSR pollutant is projected to occur if the sum of the difference 

between the projected actual emissions ... and the baseline actual emissions ... equals or exceeds the significant amount for 

that pollutant ...

8 40 CFR 52.21(a)(2)(iv)(d), Actual-to-potential test for projects that only involve construction of new emissions units, states: 

A significant emissions increase of a regulated NSR pollutant is projected to occur if the sum of the difference between the 

potential to emit ... and the baseline actual emissions ... equals or exceeds the significant amount for that pollutant ...
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While potential emission estimates have not been relied upon for purposes of the PSD project emission 

increase analysis, potential emissions are detailed for documentation of the facility estimated potential 

emissions following the project.

3.3.2 Baseline Actual Emissions

Baseline actual emissions are defined in GRAQC 391-3-1-.02(7)(a)2(i)(I): 

For any existing electric utility steam generating unit, baseline actual emissions 

means the average rate, in tons per year, at which the unit actually emitted the 

pollutant during any consecutive 24-month period selected by the owner or operator 

within the 5-year period immediately preceding when the owner or operator begins 

actual construction of the project. ...

3.3.3 Projected Actual Emissions

Projected actual emissions are defined by GRAQC 391-3-1-.02(7)(a)2(ii)(I):

“Projected actual emissions” means the maximum annual rate, in tons per year, at 

which an existing emissions unit is projected to emit a regulated NSR pollutant in any 

one of the 5 years (12-month period) following the date the unit resumes regular 

operation after the project, or in any one of the 10 years following that date, if the 

project involves increasing the emissions unit’s design capacity or its potential to 

emit that regulated NSR pollutant and full utilization of the unit would result in a 

significant emissions increase or a significant net emissions increase at the major 

stationary source.

In determining projected actual emissions, following GRAQC 391-3-1-.02(7)(a)2(ii)(II)I, the source:

Shall consider all relevant information, including but not limited to, historical 

operational data, the company’s own representations, the company’s expected 

business activity and the company’s highest projections of business activity, the 

company’s filings with the State or Federal regulatory authorities, and compliance 

plans under the approved State Implementation Plan.

In addition, when calculating projected actual emissions, OPC Chattahoochee can exclude emissions that 

could have been accommodated prior to the project and that are unrelated to the project, pursuant to 

GRAQC 391-3-1-.02(7)(a)2(ii)(II)III.

3.3.4 Could Have Accommodated Emissions

An exclusion, per GRAQC 391-3-1-.02(7)(a)2(ii)(II)III, is included in the definition of projected actual 

emissions and is a value that can be subtracted from the projected actual emissions for existing emission 

units:

May exclude, in calculating any increase in emissions that results from the particular 

project, [1] that portion of the unit’s emissions following the project that an existing 

unit could have accommodated during the consecutive 24-month period used to 

establish the baseline actual emissions under subparagraph (7)(a)2.(i) of this rule 

and that is also [2] unrelated to the particular project, including any increased 
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utilization due to product demand growth (the increase in emissions that may be 

excluded under this subparagraph shall hereinafter be referred to as “demand 

growth emissions”)... [numbers 1 and 2 added]

3.3.5 Additional Associated Emission Unit Increases

In addition to the emission increases from new or modified units, emission increases from associated 

emission units that may realize an increase in emissions due to a project must be included in the 

assessment of the project emissions increases. OPC Chattahoochee anticipates that the modifications to and 

increased utilization of the combustion turbines would result in an associated increase in drift loss and, 

therefore, air emissions from the facility’s cooling tower. As such, an associated emissions increases are 

included in this analysis for the cooling towers.

3.4 Baseline Actual Emissions

The most recent 5 year lookback period was utilized for this analysis. Accordingly, a period of May 2016 to 

April 2018 was selected as the 2 year (consecutive 24-month) baseline period for all pollutants except for 

CO, for which the period of August 2015 to July 2017 was selected. Baseline actual emissions data utilized 

for the NSR analysis for each combined cycle combustion unit can be found in Appendix B. 

3.5 Projected Actual Emissions

Projected actual emissions for the modified equipment were determined for use in the NSR analysis, based 

on the highest projected level of actual annual utilization of the modified combustion turbine systems in the 

ten years following the project (at 30.2 x 106 MMBtu/yr total for both CCCTs), and estimated actual emission 

factors derived from facility operations, as summarized in Table 3-1.
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Table 3-1. Criteria Pollutant Projected Actual Emission Factors for CCCT Units

Pollutant

Emission 

Factor

(lb/MMBtu)

VOC1

1.00E-03

PM10/PM2.5

2

6.00E-03

SO2

3

6.00E-04

NOX

4

1.01E-02

CO4

4.48E-03

H2SO4

5

6.89E-05

CO2

6

118.86

CH4

7

2.20E-03

N2O

7

2.20E-04

CO2e

7

118.98

where:

Cgas, VOC as CH4 = 0.596

M WVOC as CH4 = 16.043 lb/lb-mol, molecular weight of CH4

Cgas, HCHO = 0.061

M WHCHO = 30.026

Fd = 8,710

%O2 = 15

CO2: 1

CH4: 25

N2O : 298

3. SO2 emissions were estimated using the default SO2 emission rate for pipeline natural gas from 40 CFR 75, Appendix D, Section 

2.3.1.1, consistent with the methodology used to report the facility's SO2 emissions under the CAMD programs.

4. The projected actual NOX and CO emission rates were conservatively based on the maximum of the monthly average emission rates 

(monthly emissions divided by monthly heat input) during the 24-month baseline period for each pollutant.

5. CO2 emissions were calculated in accordance with 40 CFR 75, Appendix G, Equation G-4 using the F-factor for natural gas, consistent 

with the methodology used to report the facility's CO2 emissions under the CAMD programs and the EPA GHG reporting rule.

7. CO2e was calculated as the sum of the emission factor for each GHG pollutant multiplied by that pollutant's global warming potential 

(GWP). GWPs were taken from 40 CFR 98, Subpart A, Table A-1:

ppmv, maximum HCHO test result for either unit at any load

lb/lb-mol, molecular weight of HCHO

%, corrected basis for exhaust gas O2 content

6. CH4 and N2O emission factors for natural gas combustion are from 40 CFR 98, Subpart C, Table C-2, converted from kg to lb, 

consistent with the methodology used to report the facility's emissions under the EPA GHG reporting rule.

4. H2SO4 emissions were calculated assuming a 7.5% conversion of SO2 to H2SO4, consistent with the facility's initial November 2000 PSD 

permit application.

1. VOC emissions were based on the most recent facility compliance testing data. The total VOC emission factor was calculated as the 

sum of the 2005 VOC as CH4 (Method 25A) test results and the 2003 formaldehyde (Method 0011) test results. A 10% safety factor 

was conservatively applied to the stack test results. The emissions concentrations (ppm @ 15% O2) were converted to emission factors 

(lb/MMBtu) using the following equation:

ppmv, maximum VOC as CH4 test result for either unit at any load

dscf/MMBtu, natural gas fuel factor from 40 CFR 60, Method 19, Table 19-2

lb/MMBtu = (Cgas, VOC as CH4 * MWVOC as CH4 + Cgas, HCHO * MWHCHO) * Fd * 2.59E-9 * 20.9 / (20.9 - %O2)

2. PM emissions are based on the average of the 2003 compliance testing results for units 8A (0.0069 lb/MMBtu) and 8B (0.0051 

lb/MMBtu). The 2003 testing was inclusive of both the filterable and condensable portions of PM. It was conservatively assumed all PM is 

less than 2.5 microns in diameter (i.e., PM2.5 = PM10 = PM).
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3.6 Could Have Accommodated Emissions

The “could have accommodated” emissions for this project are based on consideration of the “Georgia 

Pacific memo” and subsequent correspondence with U.S. EPA, indicating that a maximum 30-day period can 

be utilized to demonstrate emissions that “could have been accommodated” by a source during the 

respective baseline period.9 Additional conservative assumptions were applied to the 30-day maximum 

period technique as outlined in the referenced Georgia Pacific memo. 

Specifically, application of an additional seasonal variation was relied upon for this analysis. The maximum 

30-day period from each season was evaluated, and used to evaluate total emissions for the entire seasonal 

period. Seasonal breakdowns were evaluated as follows;

Spring: March – May

Summer: June – August

Fall: September – November

Winter: December – February

Emissions that were excluded using this methodology are necessarily unrelated to the proposed project as 

they are based on existing capacity and actual data from the selected baseline period.

Additional data regarding the “could have been accommodated” analysis is included in Appendix B. 

3.7 NSR Emissions Increase Summary

Table 3-2 shows the total emissions increase of the proposed project compared to the PSD major 

modification thresholds.10 Note that the applicable NOX SER is the same under both the PSD and NNSR 

permitting programs (40 tpy). Detailed emission calculations can be found in Appendix B of this application 

report.

9 https://www.epa.gov/nsr/response-georgia-pacific-use-demand-growth-exclusion-projected-actual-emissions

10 AP-42, Chapter 3, Section 1, Stationary Gas Turbines, lists the Pb emission factor for natural gas turbines as ND (no 

detect); therefore, Pb emissions increases for the proposed project were not evaluated.
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Table 3-2. Project Emissions Increase

3.8 Potential Emissions Estimate

The following sections discuss the methodology used to calculate the potential emissions for each emission 

unit at the facility.

3.8.1 Combined Cycle Combustion Turbines

The potential emissions for each CCCT (i.e., combustion turbine with HRSG and duct burner, discharging to 

a common stack) are determined on a pollutant‐by‐pollutant basis. Table 3-3 summarizes the criteria 

pollutant emission factors utilized for estimation of potential emissions from both CCCT units. 

Baseline 

Actual 

Emissions

(tpy)

"Could Have 

Accommodated" 

Emissions

(tpy)

Projected 

Actual 

Emissions

(tpy)

Project 

Emissions 

Increase1

(tpy)

NOX 100.2 116.4 153.1 36.7 - 36.7 40 No

CO 19.0 30.0 67.6 37.6 - 37.6 100 No

VOC 11.6 13.5 15.1 1.59 - 1.6 40 No

PM 69.7 81.1 90.6 9.5 0.31 9.8 25 No

PM10 69.7 81.1 90.6 9.5 0.27 9.8 15 No

PM2.5 69.7 81.1 90.6 9.5 1.5E-03 9.5 10 No

SO2 7.0 8.1 9.1 0.95 - 0.9 40 No

H2SO4 0.80 0.93 1.0 0.11 - 0.1 7 No

CO2e

3 1,382,762 1,608,206 1,796,567 188,361 - 188,361 75,000 No

2. 40 CFR 52.21(b)23(i) and Georgia Air Quality Control Rule 391-3-1-.03(8)(c)15

1. Project Emissions Increase = (Projected Actual Emissions - Baseline Actual Emissions) - ("Could Have Accommodated" Emissions - Baseline Actual Emissions)

3. NSR permitting for CO2e is only required if the project emissions increase exceeds the NSR SER of 75,000 tpy and if NSR permitting is triggered for at least one other 

regulated pollutant.

Pollutant

Units 8A and 8B Cooling 

Tower 

Associated 

Emissions 

Increase

(tpy)

NSR 

Significant 

Emission 

Rate2

(tpy)

NSR 

Triggered?

Total 

Project 

Emissions 

Increase

(tpy)
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Table 3-3. Criteria Pollutant Emission Factors for CCCT Units

Emission Factor

Pollutant (lb/MMBtu)

NOX

1

1.11E-02

CO24.48E-03

VOC32.59E-03

PM49.91E-03

Total PM10

4

9.91E-03

Total PM2.5

4

9.91E-03

SO2

5

6.00E-04

H2SO4

6

6.89E-05

CO2

7

1.19E+02

CH4

8

2.20E-03

N2O

8

2.20E-04

CO2e

9

1.19E+02

 Pollutant GWP

 CO2 1

 CH4 25

 N2O 298

4. Condition 3.3.6.c limits PM to 0.011 lb/MMBtu, LHV basis. The limit was adjusted to HHV 

basis using a HHV/LHV ratio of 1.109805, consistent with the ratio used by Siemens in its 

performance data sheet for TPU1 dated 1/12/2020. It was conservatively assumed all PM is 

less than 2.5 microns in diameter (i.e., PM2.5 = PM10 = PM).

5. SO2 emissions were estimated using the default SO2 emission rate for pipeline natural gas 

from 40 CFR 75, Appendix D, Section 2.3.1.1, consistent with the methodology used to 

report the facility's SO2 emissions under the CAMD programs.

6. H2SO4 emissions were calculated assuming a 7.5% conversion of SO2 to H2SO4, 

consistent with the facility's initial November 2000 PSD permit application.

7. CO2 emissions were calculated in accordance with 40 CFR 75, Appendix G, Equation G-4 

using the F-factor for natural gas, consistent with the methodology used to report the 

facility's CO2 emissions under the CAMD programs and the EPA GHG reporting rule.

8. CH4 and N2O emission factors for natural gas combustion are from 40 CFR 98, Subpart C, 

Table C-2, converted from kg to lb, consistent with the methodology used to report the 

facility's emissions under the EPA GHG reporting rule.

9. Total GHG emissions in CO2e is the sum of the product of each GHG and its respective 

global warming potential (GWP) per 40 CFR Part 98 Subpart A, Table A-1, effective January 

1, 2014.

3. VOC emission factor based on 2.0 ppm @ 15% O2 existing BACT limit.

1. Emission factor for NOX based on 3.0 ppm @ 15% O2 existing BACT limit. Permit 

Condition 3.3.4 limits NOX emissions to 179.6 tpy (total from all CCCTs).

2. Emission factor for CO based on 2.0 ppm @ 15% O2 existing BACT limit. Permit Condition 

3.3.5 limits CO emissions to 86 tpy (total from all CCCTs).
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3.8.2 HAP/TAP Emissions

HAP and toxic air pollutant (TAP) emissions are evaluated from each CCCT using AP-42 based emission 

factors and vendor based information, as appropriate. Details regarding the estimation of HAP/TAP 

emissions can be found in Appendix C. 

3.8.3 Cooling Tower

Cooling tower emissions, as found in Appendix B, are calculated based on a vendor based drift rate, and 

facility records of the Total Dissolved Solids (TDS) concentration present in the waters processed at the 

cooling tower. This data is relied upon using emission estimation methods for cooling towers outlined in 

Calculating Realistic PM10 Emissions from Cooling Towers by Joel Reisman and Gordon Frisbie, 2002, to 

estimate potential emissions from the facility cooling towers. 

3.8.4 Insignificant Emissions Sources

The facility has other small insignificant sources of emissions (e.g., fugitive piping leaks, roads, etc.) at the

facility which are not quantified within the potential to emit estimates within this application. 
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4. REGULATORY APPLICABILITY ANALYSIS

The project will be subject to certain federal and state air regulations. This section of the application 

summarizes the air permitting requirements and key air quality regulations that will potentially apply to OPC 

Chattahoochee as a result of the proposed project. Applicability to NSR, Title V, NSPS, National Emission 

Standards for Hazardous Air Pollutants (NESHAP), GRAQC, and other potentially applicable regulations to 

the proposed project are addressed herein.

4.1 New Source Review Applicability

The NSR permitting program generally requires a source to obtain a permit and undertake other obligations 

prior to construction of any project at an industrial facility if the proposed project results in an emissions 

increase in excess of certain pollutant threshold levels. EPD administers its major NSR permitting program 

through GRAQC Rule 391-3-1-.02(7), Prevention of Significant Deterioration of Air Quality, which establishes 

preconstruction, construction, and operation requirements for new and modified sources.

The federal NSR program is comprised of two elements: NNSR and PSD. The NNSR program potentially 

applies to new construction or modifications that result in emission increases of a particular pollutant for 

which the area where the facility is located is classified as “nonattainment” for that pollutant. The PSD 

program applies to project increases of those pollutants for which the area the facility is located in is 

classified as “attainment” or “unclassifiable.” OPC Chattahoochee is located in Heard County, which has 

been designated by the U.S. EPA as “attainment” or “unclassifiable” for all criteria pollutants.11 Therefore, 

PSD is the applicable permitting program under the federal NSR program. In addition to the federal NSR 

programs, the facility is located in a county specified by the Georgia EPD as subject to GRAQC 391-3-1-

.03(8)(c)(15), which addresses additional provisions for electrical generating units in the areas contributing 

to the Atlanta ozone nonattainment area. This state regulation specifies that certain NNSR provisions are 

potentially applicable when permitting new construction or modifications at any electrical generating unit 

that is located in a listed contributing county and that has facility-wide potential NOX emissions exceeding 

100 tpy.12

The PSD program only regulates emissions from “major” stationary sources of regulated air pollutants. A 

stationary source is considered PSD major if potential emissions of any regulated pollutant exceed the major 

source thresholds. The PSD major source threshold for OPC Chattahoochee is 100 tpy for all regulated 

pollutants, except GHG.13, 14 OPC Chattahoochee is classified as an existing PSD major source since potential 

emissions of at least one regulated pollutant exceeds 100 tpy. For sources which are PSD major for at least 

one regulated pollutant, the emissions increases for all regulated pollutants resulting from the proposed 

project must be compared against the PSD SER to determine if the project is subject to PSD review. For 

CO2e, PSD permitting is only required if the emissions increase from the proposed project exceeds the SER 

for CO2e and the project is already undergoing PSD permitting for at least one other PSD-regulated 

pollutant. OPC Chattahoochee is also an existing major source under the state NNSR permitting program for 

electric generating units in contributing counties, as it has potential NOX emissions exceeding the major 

11 40 CFR 81.311

12 GRAQC 391-3-1-.03(8)(c)15(i)

13 Fossil fuel-fired steam electric plants of more than 250 MMBtu/hr input (which includes combined cycle natural gas plants) 

are on the “List of 28” named source categories which are subject to a lower major source threshold for criteria pollutants of 

100 tpy.

14 40 CFR 52.21(b)(49)(iii)
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source threshold of 100 tpy. Therefore, the NOX emissions increase for the proposed project must be 

compared to the NOX NNSR SER to determine the applicability to certain NNSR provisions.

The emissions increases from the proposed project for each regulated pollutant compared to the respective 

SERs are shown in Table 4-1. Note that the applicable NOX SER is the same under both the PSD and NNSR 

permitting programs (40 tpy).

Table 4-1. Project Emission Increases Compared to PSD and NNSR SERs

As illustrated in Table 4-1, the project emissions increases do not exceed the SERs for any pollutant. 

Accordingly, neither PSD nor NNSR review is required.

4.2 Title V Operating Permits

40 CFR 70 establishes the federal Title V operating permit program. Georgia has incorporated the provisions 

of this federal program in its state regulation, Rule 391-3-1-.03(10), Title V Operating Permits. This 

regulation requires that all new and existing Title V major sources of air emissions obtain federally-approved 

state-administered operating permits. A major source as defined under the Title V program is a facility that 

has the potential to emit either more than 100 tpy for any criteria pollutant, more than 10 tpy for any single 

HAP, or more than 25 tpy for combined HAP. Potential emissions from OPC Chattahoochee exceed the 

major source threshold for several pollutants. Therefore, OPC Chattahoochee is subject to the Title V 

program and currently operates under the State issued Part 70 Operating Permit No. 4911-149-0006-

V-05-0.

The proposed project involves a Title I (NSPS) modification and, therefore, represents a significant 

modification of the operating permit. As such, the required Title V modification application elements are 

included in the GEOS submittal with application ID No. 486572.

4.3 New Source Performance Standards

NSPS, promulgated in 40 CFR 60, require new, modified, or reconstructed sources to control emissions to 

the level achievable by the best demonstrated technology as specified in the applicable provisions. The 

Baseline 

Actual 

Emissions

(tpy)

"Could Have 

Accommodated" 

Emissions

(tpy)

Projected 

Actual 

Emissions

(tpy)

Project 

Emissions 

Increase1

(tpy)

NOX 100.2 116.4 153.1 36.7 - 36.7 40 No

CO 19.0 30.0 67.6 37.6 - 37.6 100 No

VOC 11.6 13.5 15.1 1.59 - 1.6 40 No

PM 69.7 81.1 90.6 9.5 0.31 9.8 25 No

PM10 69.7 81.1 90.6 9.5 0.27 9.8 15 No

PM2.5 69.7 81.1 90.6 9.5 1.5E-03 9.5 10 No

SO2 7.0 8.1 9.1 0.95 - 0.9 40 No

H2SO4 0.80 0.93 1.0 0.11 - 0.1 7 No

CO2e

3 1,382,762 1,608,206 1,796,567 188,361 - 188,361 75,000 No

2. 40 CFR 52.21(b)23(i) and Georgia Air Quality Control Rule 391-3-1-.03(8)(c)15

1. Project Emissions Increase = (Projected Actual Emissions - Baseline Actual Emissions) - ("Could Have Accommodated" Emissions - Baseline Actual Emissions)

3. NSR permitting for CO2e is only required if the project emissions increase exceeds the NSR SER of 75,000 tpy and if NSR permitting is triggered for at least one other 

regulated pollutant.

Pollutant

Units 8A and 8B Cooling 

Tower 

Associated 

Emissions 

Increase

(tpy)

NSR 

Significant 

Emission 

Rate2

(tpy)

NSR 

Triggered?

Total 

Project 

Emissions 

Increase

(tpy)
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following is a summary of applicability and non-applicability determinations for NSPS regulations of 

relevance to the proposed project. Rules that are specific to certain source categories unrelated to the 

proposed project are not discussed in this regulatory review.

4.3.1 40 CFR 60 Subpart A – General Provisions

All affected sources subject to source-specific NSPS are subject to the general provisions of NSPS Subpart A 

unless specifically excluded by the source-specific NSPS. Subpart A requires initial notification, performance 

testing, recordkeeping and monitoring, provides reference methods, and mandates general control device 

requirements for all other subparts as applicable.

4.3.2 40 CFR 60 Subpart D – Fossil Fuel-Fired Steam Generators > 250 MMBtu/hr

NSPS Subpart D, Standards of Performance for Fossil-Fuel-Fired Steam Generators, applies to fossil fuelfired steam generating units with heat input capacities greater than 250 MMBtu/hr that have been 

constructed or modified since August 17, 1971.15 The rule defines a fossil fuel-fired steam generating unit 

as:16

A furnace or boiler used in the process of burning fossil fuel for the purpose of 

producing steam by heat transfer.

The combustion turbines and duct burners will not be subject to NSPS Subpart D. The combustion turbines 

are not classified as steam generating units under this NSPS. The duct burners each have a rated heat input 

capacity of 95 MMBtu/hr, which is below the applicability threshold of concern for the rule. 

4.3.3 40 CFR 60 Subpart Da – Electric Utility Steam Generating Units

NSPS Subpart Da, Standards of Performance for Electric Utility Steam Generating Units, provides standards 

of performance for electric utility steam generating units with heat input capacities greater than 

250 MMBtu/hr of fossil fuel (alone or in combination with any other fuel) for which construction, 

modification, or reconstruction commenced after September 18, 1978.17 The term “steam generating unit” is 

defined under this regulation as:18

For units constructed, reconstructed, or modified after May 3, 2011, steam 

generating unit means any furnace, boiler, or other device used for combusting fuel 

for the purpose of producing steam (including fossil-fuel-fired steam generators 

associated with combined cycle gas turbines... 

The combustion turbines and duct burners will not be subject to NSPS Subpart Da, because:

► The combustion turbines are not classified as steam generating units under this regulation;

► The duct burners do not have a heat input capacity of greater than 250 MMBtu/hr each; and

15 40 CFR 60.40

16 40 CFR 60.41

17 40 CFR 60.40Da(a)

18 40 CFR 60.41Da
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► Heat recovery steam generators and duct burners that are subject to NSPS Subpart KKKK are not subject 

to NSPS Subpart Da. Following the proposed modifications, OPC Chattahoochee’s combustion turbines 

and HRSG with duct burners will be NSPS Subpart KKKK affected facilities.19

4.3.4 40 CFR 60 Subpart Db – Steam Generating Units > 100 MMBtu/hr

NSPS Subpart Db, Standards of Performance for Industrial-Commercial-Institutional Steam Generating Units, 

provides standards of performance for steam generating units with capacities greater than 100 MMBtu/hr 

for which construction, modification, or reconstruction commenced after June 19, 1984.20 The term “steam 

generating unit” is defined under this regulation as:21

Steam generating unit means a device that combusts any fuel or byproduct/waste 

and produces steam or heats water or heats any heat transfer medium. This term 

includes any municipal-type solid waste incinerator with a heat recovery steam 

generating unit or any steam generating unit that combusts fuel and is part of a 

cogeneration system or a combined cycle system. This term does not include process 

heaters as they are defined in this subpart.

The combustion turbines and duct burners will not be subject to NSPS Subpart Db, because:

► The combustion turbines are not classified as steam generating units under this regulation;

► The duct burners do not have a heat input capacity of greater than 100 MMBtu/hr each; and

► Heat recovery steam generators and duct burners that are subject to NSPS Subpart KKKK are not subject 

to NSPS Subpart Db. Following the proposed modifications, OPC Chattahoochee’s combustion turbines 

and HRSG with duct burners will be NSPS Subpart KKKK affected facilities.22

4.3.5 40 CFR 60 Subpart Dc – Small Steam Generating Units

NSPS Subpart Dc, Standards of Performance for Small Industrial-Commercial-Institutional Steam Generating 

Units, provides standards of performance for each steam generating unit for which construction, 

modification, or reconstruction commenced after June 9, 1989.23 The term “steam generating unit” is 

defined under this regulation as:24

Steam generating unit means a device that combusts any fuel and produces steam 

or heats water or heats any heat transfer medium. This term includes any duct 

burner that combusts fuel and is part of a combined cycle system. This term does 

not include process heaters as defined in this subpart.

The duct burners at OPC Chattahoochee are currently subject to NSPS Subpart Dc, as they each have a 

rated heat input capacity of 95 MMBtu/hr and were each constructed after 1989. However, neither the 

combustion turbines nor the duct burners will be subject to NSPS Subpart Dc after the completion of the 

proposed project, because:

19 40 CFR 60.40Da(e)

20 40 CFR 60.40b(a)

21 40 CFR 60.41b

22 40 CFR 60.40b(i)

23 40 CFR 60.40c(a)

24 40 CFR 60.41c
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► The combustion turbines do not meet the definition of steam generating units; and

► Heat recovery steam generator and duct burner units that are subject to NSPS Subpart KKKK are not 

subject to NSPS Subpart Dc. Following the proposed modifications, OPC Chattahoochee’s combustion 

turbines and HRSG with duct burners will be NSPS Subpart KKKK affected facilities.25

4.3.6 40 CFR 60 Subpart GG – Stationary Gas Turbines

NSPS Subpart GG, Standards of Performance for Stationary Gas Turbines, applies to all stationary gas 

turbines with a heat input at peak load equal to or greater than 10 MMBtu/hr, based on the lower heating 

value of the fuel fired, that are constructed, modified, or reconstructed after October 3, 1977.26

Presently, the combustion turbines at OPC Chattahoochee are subject to NSPS Subpart GG. However, upon 

completion of the proposed modifications, the combustion turbine systems will be subject to the more 

recently promulgated standards for Stationary Combustion Turbines under NSPS Subpart KKKK. Pursuant to 

40 CFR 60.4305(b) (NSPS Subpart KKKK), stationary combustion turbines regulated under NSPS Subpart 

KKKK are exempt from the requirements of NSPS Subpart GG. Therefore, NSPS Subpart GG will no longer 

apply to the OPC Chattahoochee combustion turbines following the proposed project.

4.3.7 40 CFR 60 Subpart KKKK – Stationary Combustion Turbines

NSPS Subpart KKKK, Standards of Performance for Stationary Combustion Turbines, applies to all stationary 

combustion turbines with a heat input at peak load equal to or greater than 10 MMBtu/hr, based on the 

lower heating value of the fuel fired, and were constructed, reconstructed, or modified after February 18, 

2005.27 OPC Chattahoochee consists of two natural gas-fired turbines, each of which was constructed prior 

to 2005 and has a heat input capacity exceeding 10 MMBtu/hr. To determine if the turbines will be subject 

to NSPS Subpart KKKK following the proposed project, it is necessary to ascertain if a “modification” per the 

NSPS has occurred. For purposes of NSPS, a modification is defined as:28

...any physical change in, or change in the method of operation of, an existing facility 

which increases the amount of any air pollutant (to which a standard applies) 

emitted into the atmosphere by that facility or which results in the emission of any 

air pollutant (to which a standard applies) into the atmosphere not previously 

emitted.

More specifically, for an existing electric utility steam generating unit:29

No physical change, or change in the method of operation, at an existing electric 

utility steam generating unit shall be treated as a modification...provided that such 

change does not increase the maximum hourly emissions of any pollutant regulated 

under this section above the maximum hourly emissions achievable at that unit 

during the 5 years prior to the change.

The CT Upgrades Project will result in an increase in the hourly heat input capacity for the combustion 

turbines. OPC has presumed that an increase in the amount of an air pollutant regulated by NSPS Subpart 

25 40 CFR 60.40c(e)

26 40 CFR 60.330

27 40 CFR 60.4305(a), (b)

28 40 CFR 60.2

29 40 CFR 60.14(h)
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KKKK could occur on a short-term (hourly) basis. Therefore, once the proposed modifications are complete, 

the OPC Chattahoochee combustion turbines will be subject to NSPS Subpart KKKK. Pursuant to 40 CFR 

60.4305(a), the associated HRSG and duct burners will also be subject to NSPS Subpart KKKK.

Per 40 CFR 60.4305(b), stationary combustion turbines regulated under NSPS Subpart KKKK are exempt 

from the requirements of NSPS Subpart GG. HRSGs and duct burners regulated under NSPS Subpart KKKK 

are also exempt from the requirements of NSPS Subparts Da, Db, and Dc.

The following sections detail the applicable requirements as a result of NSPS Subpart KKKK applicability.

4.3.7.1 Emission Limits

Per Table 1 to NSPS Subpart KKKK, a modified combustion turbine is subject to NOX emission limits 

depending on the type of fuel combusted and the heat input at peak load. For modified combustion turbines 

firing natural gas with a rating greater than 850 MMBtu/hr, the NOX emission standard is 15 ppm at 15% O2

or 0.43 lb/MWh useful output. NSPS Subpart KKKK also includes, for units greater than 30 MW output, a 

NOX limit of 96 ppm at 15% O2 or 4.7 lb/MWh useful output for turbine operation at ambient temperatures 

less than 0°F and turbine operation at loads less than 75% of peak load.30 Compliance with the NOX

emission limit is determined on a 30 unit operating day rolling average basis.31 As the combustion turbines 

and duct burners are presently subject to a NOX limitation of 3.0 ppm at 15% O2, 4-hour average per 

Condition 3.3.6.a of the existing Title V operating permit, the new NSPS Subpart KKKK NOX limitations will 

be subsumed by the facility’s NOX BACT limitation.

SO2 emissions from combustion turbines located in the continental U.S. are limited to 0.9 lb/MWh gross 

output (or 110 ng/J), or the units must not burn any fuel with total potential sulfur emissions in excess of 

0.060 lb SO2/MMBtu heat input.32

4.3.7.2 Monitoring and Testing Requirements

Pursuant to 40 CFR 60.4333(a), the combustion turbines, air pollution control equipment, and monitoring 

equipment will be maintained in a manner that is consistent with good air pollution control practices for 

minimizing emissions. This requirement applies at all times including during startup, shutdown, and 

malfunction.

4.3.7.2.1 NOX Compliance Demonstration Requirements

The combustion turbine systems presently employ a continuous emission monitoring system (CEMS) for NOX

per the requirements of the Acid Rain Program (ARP), promulgated in 40 CFR Part 75. Pursuant to 40 CFR 

60.4340(b)(1) and 40 CFR 60.4345, OPC Chattahoochee can rely on its existing NOX CEMS installed and 

certified according to 40 CFR Part 75 Appendix A to demonstrate ongoing compliance with the NSPS Subpart 

KKKK NOX emission limits. Sources demonstrating compliance with the NOX emission limit via CEMS are not 

subject to the requirement to perform initial and annual NOX stack tests.33 Initial compliance with the NOX

emission limit will be demonstrated by comparing the arithmetic average of the NOX emissions 

30 Table 1 to Subpart KKKK of Part 60

31 40 CFR 60.4350(h), 40 CFR 60.4380(b)(1)

32 40 CFR 60.4330(a)(1) or (a)(2), respectively

33 40 CFR 60.4340(b), 40 CFR 60.4405
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measurements taken during the initial relative accuracy test audit (RATA) required pursuant to 40 CFR 

60.4405 to the NOX emission limit under this subpart.34

4.3.7.2.2 SO2 Compliance Demonstration Requirements

For compliance with the SO2 emission limit, facilities are required to perform regular determinations of the 

total sulfur content of the combustion fuel and to conduct initial and annual compliance demonstrations. 

The total sulfur content of gaseous fuel combusted in the combustion turbine must be determined and 

recorded once per operating day or using a custom schedule as approved by EPD;35 however, OPC elects to 

opt out of this provision of the rule by using a fuel that is demonstrated not to exceed potential sulfur 

emissions of 0.060 lb/MMBtu SO2.

36 This demonstration can be made using one of the following methods:

► By using a purchase contract specifying that the fuel sulfur content for the natural gas is less than or 

equal to 20 grains of sulfur per 100 standard cubic feet and results in potential emissions not exceeding 

0.060 lb/MMBtu; or

► By using representative fuel sampling data meeting the requirements of 40 CFR 75, Appendix D, 

Sections 2.3.1.4 or 2.3.2.4 which show that the sulfur content of the fuel does not exceed 

0.060 lb SO2/MMBtu heat input.

OPC is currently required to monitor the sulfur content of the natural gas burned in the combustion turbines 

and duct burners through submittal of a semiannual analysis of the gas by the supplier or the facility to 

demonstrate that the sulfur content does not exceed its excursion threshold of 0.27 grains per 100 standard 

cubic feet.37 This sulfur content analysis by the supplier or OPC satisfies the sulfur content demonstration 

requirement of 40 CFR 60.4365. Therefore, continued compliance with this existing permit condition will 

guarantee compliance with the NSPS Subpart KKKK sulfur monitoring requirement.

4.3.7.3 Initial Notification

Per 40 CFR 60.7(a)(4), this permit application serves as the required notification for any physical or 

operational change to an existing facility which qualifies as an NSPS modification.

4.3.8 40 CFR 60 Subpart TTTT – Greenhouse Gas Emissions for Electric Generating 

Units

NSPS Subpart TTTT, Standards of Performance for Greenhouse Gas Emissions for Electric Generating Units,

applies to any fossil fuel fired steam generating unit, Integrated Gasification Combined Cycle (IGCC) unit, or 

stationary combustion turbine constructed after January 8, 2014 or reconstructed after June 18, 2014, and 

to any steam generating unit or IGCC modified after June 18, 2014, provided that unit has a base load 

rating greater than 250 MMBtu/hr and serves a generator capable of selling greater than 25 MW of 

electricity to the grid.38 The existing CCCT generating units for OPC Chattahoochee each have peak heat 

inputs greater than 250 MMBtu/hr and serve a generator greater than 25 MW. Therefore, the CCCT 

generating units (including the duct burners) could potentially be subject to the provisions of NSPS TTTT.

34 40 CFR 60.4405(c)

35 40 CFR 60.4370(b) and (c)

36 40 CFR 60.4365

37 Permit No. 4911-149-0006-V-05-0, Conditions 5.2.3, 5.2.4, 6.1.7.c.i.

38 40 CFR 60.5509(a)
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With respect to stationary combustion turbines, NSPS Subpart TTTT applies only to units that commenced 

construction or reconstruction after the specified dates, not modification. “Reconstruction” is defined under 

40 CFR 60 Subpart A as the replacement of components of an existing affected facility such that the fixed 

capital cost of the new components exceeds 50% of the fixed capital cost that would be required to 

construct a comparable, entirely new affected facility that is technologically and economically capable of 

complying with the applicable standards.39 The total cost of the TPU1 and LLTD upgrades is well under 50% 

of the cost for two comparable new units. As the combustion turbines at OPC Chattahoochee are existing 

units and the proposed project does not meet the reconstruction definition, the modifications to the turbine 

systems will not trigger applicability of NSPS Subpart TTTT requirements.40

4.3.9 Non-Applicability of All Other NSPS

NSPS are developed for particular industrial source categories. The applicability of a particular NSPS to the 

proposed project can be readily ascertained based on the industrial source category covered. All other 

NSPS, besides Subpart A, are categorically not applicable to the proposed project.

4.4 National Emission Standards for Hazardous Air Pollutants

NESHAP, located in 40 CFR 61 and 40 CFR 63, have been promulgated for source categories that emit HAP 

to the atmosphere. A facility that is a major source of HAP is defined as having potential emissions of 

greater than 25 tpy of total HAP and/or 10 tpy of individual HAP. Facilities with a potential to emit HAP at an 

amount less than that which is defined as a major source are otherwise considered an area source. Under 

40 CFR 63, the NESHAP allowable emissions limits are most often established on the basis of a maximum 

achievable control technology (MACT) determination for the particular major source. These NESHAP apply to 

sources in specifically regulated industrial source categories (Clean Air Act Section 112(d)) or on a case-bycase basis (Section 112(g)) for facilities not regulated as a specific industrial source type.

Although emissions from OPC Chattahoochee alone do not exceed the HAP major source thresholds, EPD 

considers OPC Chattahoochee to be part of one Title V site that includes other neighboring utility units, 

which are operated by other entities.41 The overall Title V site is a major source of HAP, and will remain so 

following the proposed project. The determination of applicability to NESHAP requirements for the proposed 

project is detailed in the following sections. Rules that are specific to certain source categories unrelated to 

the proposed project are not discussed in this regulatory review.

4.4.1 40 CFR 63 Subpart A – General Provisions

NESHAP Subpart A, General Provisions, contains national emission standards for HAP defined in 

Section 112(b) of the Clean Air Act. All affected sources, which are subject to another NESHAP in 40 CFR 63, 

are subject to the general provisions of NESHAP Subpart A, unless specifically excluded by the sourcespecific NESHAP.

4.4.2 40 CFR 63 Subpart YYYY – Combustion Turbines

NESHAP Subpart YYYY, NESHAP for Stationary Combustion Turbines, establishes emission and operating 

limitations for stationary combustion turbines at major sources of HAP. A stationary combustion turbine is 

39 40 CFR 60.15

40 40 CFR 60.5509(a)

41 See Section 1.1 of OPC Chattahoochee’s Title V operating permit for additional information on EPD’s site determination.
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defined as “existing” if the affected source was constructed or reconstructed prior to January 14, 2003. The 

two combustion turbines at OPC Chattahoochee were constructed prior to that applicability date.

Reconstruction for the purposes of the NESHAP in 40 CFR 63 is defined as:42

The replacement of components of an affected or a previously nonaffected source to 

such an extent that:

(1) The fixed capital cost of the new components exceeds 50 percent of the fixed 

capital cost that would be required to construct a comparable new source;

As discussed in Section 4.3.8, the proposed project will not exceed more than 50% of the cost of two 

comparable new combustion turbines. Therefore, the combustion turbines at OPC Chattahoochee will 

remain existing sources under Subpart YYYY following the proposed project.

Pursuant to 40 CFR 63.6090(b)(4), 

Existing stationary combustion turbines in all subcategories do not have to meet the 

requirements of this subpart and of subpart A of this part. No initial notification is 

necessary for any existing stationary combustion turbine, even if a new or 

reconstructed turbine in the same category would require an initial notification.

Therefore, while NESHAP Subpart YYYY does apply to the facility combustion turbines, the turbines do not 

have to meet the requirements of the subpart, including the requirement for an initial notification. 

4.4.3 40 CFR 63 Subpart DDDDD – Industrial, Commercial, and Institutional 

Boilers and Process Heaters

NESHAP Subpart DDDDD, National Emissions Standards for Hazardous Air Pollutants for Major Sources: 

Industrial, Commercial, and Institutional Boilers and Process Heaters (Major Source Boiler MACT) regulates 

boilers and process heaters at major sources of HAP. Pursuant to 40 CFR 63.7575:

Boiler means an enclosed device using controlled flame combustion and having the 

primary purpose of recovering thermal energy in the form of steam or hot water. 

Controlled flame combustion refers to a steady-state, or near steady-state, process 

wherein fuel and/or oxidizer feed rates are controlled. A device combusting solid 

waste, as defined in §241.3 of this chapter, is not a boiler unless the device is 

exempt from the definition of a solid waste incineration unit as provided in section 

129(g)(1) of the Clean Air Act. Waste heat boilers are excluded from this definition.

Waste heat boiler means a device that recovers normally unused energy (i.e., hot 

exhaust gas) and converts it to usable heat. Waste heat boilers are also referred to 

as heat recovery steam generators. Waste heat boilers are heat exchangers 

generating steam from incoming hot exhaust gas from an industrial (e.g., thermal 

oxidizer, kiln, furnace) or power (e.g., combustion turbine, engine) equipment. Duct 

burners are sometimes used to increase the temperature of the incoming hot 

exhaust gas.

42 40 CFR 63.2
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The rule defines a “boiler” as an enclosed device using controlled combustion to recover thermal energy in 

the form of steam and/or hot water. The combustion turbines at the OPC Chattahoochee use the thermal 

energy of natural gas directly through combustion and without use of steam or hot water. Therefore, they 

do not fall within the definition of a “boiler” and are not subject to the rule.

As the definition of “boiler” also specifically excludes “waste heat boilers,” the heat recovery steam 

generators and duct burners at the OPC Chattahoochee are not subject to NESHAP Subpart DDDDD. 

Therefore, NESHAP Subpart DDDDD does not apply to the facility or the proposed project.

4.4.4 40 CFR 63 Subpart UUUUU – Electric Utility Steam Generating Units

NESHAP Subpart UUUUU, NESHAP for Electric Utility Steam Generating Units, applies to electric utility steam 

generating units (EGUs) that combust coal or oil.43 As the OPC Chattahoochee combustion turbines and duct 

burners combust natural gas only, NESHAP Subpart UUUUU does not apply to the facility or the proposed 

project. 

4.4.5 40 CFR 63 Subpart JJJJJJ – Industrial, Commercial, and Institutional Boilers 

at Area Sources

NESHAP Subpart JJJJJJ, NESHAP for Industrial, Commercial, and Institutional Boilers Area Sources (Area 

Source Boiler MACT) regulates boilers at area sources of HAP.44 As the Title V site where OPC 

Chattahoochee is located is a major source of HAP, NESHAP Subpart JJJJJJ does not apply to the facility or 

the proposed project. Further, even if the facility were classified as an area source of HAP, the regulation 

still would not apply, because the combustion turbines do not meet the definition of a boiler45, waste heat 

boilers (including the heat recovery steam generators and duct burners) are excluded from the definition of 

a boiler46, and gas-fired units are exempt from Subpart JJJJJJ47. 

4.4.6 Non-Applicability of All Other NESHAP

NESHAP are developed for particular industrial source categories. The applicability of a particular NESHAP to 

the proposed project can be readily ascertained based on the industrial source category covered. All other 

NESHAP are categorically not applicable to the proposed project.

4.5 Compliance Assurance Monitoring

Under 40 CFR 64, Compliance Assurance Monitoring (CAM), facilities are required to prepare and submit 

monitoring plans for certain emissions units as part of Title V operating permit applications. The CAM plans 

are intended to provide an on-going and reasonable assurance of compliance with emission limits for units 

equipped with air pollution control devices. Pursuant to 40 CFR 64.2(b)(1)(vi), emission limits for which a 

Part 70 Permit specifies a continuous compliance determination method are exempt from CAM 

requirements. Since Condition 5.2.1 of OPC Chattahoochee’s permit requires the operation of NOX and CO 

CEMS for both CCCT stacks, EPD has previously determined that the emission units are exempt from CAM. 

Therefore, no CAM documentation has been included within this permit application.

43 40 CFR 63.9980

44 40 CFR 63.11193

45 40 CFR 63.11237

46 Ibid.

47 40 CFR 63.11195(e)
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4.6 Risk Management Plan

Subpart B of 40 CFR 68 outlines requirements for Risk Management Plans (RMP) pursuant to Section 112(r) 

of the Clean Air Act. Applicability of the subpart is determined based on the type and quantity of chemicals 

stored at a facility. OPC Chattahoochee operates a tank storing aqueous ammonia (greater than 20% 

concentration) in amounts exceeding the applicability threshold listed in 40 CFR 68 Subpart F of 20,000 

pounds. Therefore, the facility is subject to and in compliance with the RMP Program 1 requirements for its 

aqueous ammonia. The proposed project will not involve changes to the facility’s ammonia storage tank or 

the concentration of ammonia stored and, therefore, will not impact the facility’s requirements under 40 CFR 

68. OPC Chattahoochee will continue to comply with the applicable provisions of this regulation.

4.7 Stratospheric Ozone Protection

The requirements originating from Title VI of the Clean Air Act, entitled Protection of Stratospheric Ozone, 

are contained in 40 CFR 82. Subparts A through E and Subparts G and H of 40 CFR 82 are not applicable to 

OPC Chattahoochee. 40 CFR 82 Subpart F, Recycling and Emissions Reduction, potentially applies if the 

facility operates, maintains, repairs, services, or disposes of appliances that utilize Class I, Class II, or nonexempt substitute refrigerants.48 Subpart F generally requires persons completing the repairs, service, or 

disposal to be properly certified. The facility utilizes certified technicians to perform repairs, service, and 

disposal of regulated refrigerants from such equipment (air conditioners, refrigerators, etc.). OPC 

Chattahoochee will continue to comply with 40 CFR 82 Subpart F.

4.8 Clean Air Markets Regulations

Starting with the Acid Rain Program (ARP) mandated by the 1990 Clean Air Act Amendments, U.S. EPA has 

developed several market-based “cap and trade” regulatory programs. All market-based regulatory 

programs are overseen by U.S. EPA’s Clean Air Markets Divisions (CAMD) and are referred to as CAMD 

regulations. The programs that are potentially applicable to OPC Chattahoochee are:

► Acid Rain Program (ARP) – 1990 - ongoing

► Clean Air Interstate Rule (CAIR) – 2009 - 2014

► Cross-State Air Pollution Rule (CSAPR) – 2015 (ongoing)

4.8.1 Acid Rain Program 

In order to reduce acid rain in the United States and Canada, Title IV (40 CFR 72 et seq.) of the Clean Air 

Act Amendments of 1990 established the ARP to substantially reduce SO2 and NOX emissions from electric 

utility plants. Affected units are specifically listed in Tables 1 and 2 of 40 CFR 73.10 under Phase I and 

Phase II of the program. Upon Phase III implementation, the ARP in general applies to fossil fuel-fired 

combustion sources that drive generators for the purposes of generating electricity for sale. The turbines at 

OPC Chattahoochee are utility units subject to the ARP. The facility is subject to the requirements of 40 CFR 

72 (permits), 40 CFR 73 (SO2), and 40 CFR 75 (monitoring) but is not subject to the NOX provisions (40 CFR 

76) of the ARP regulations because the turbines do not have the capability to burn coal. 

Under 40 CFR 75 of the ARP, OPC Chattahoochee is required to operate a NOX CEMS for each unit to 

monitor the NOX emission rate (lb/MMBtu) and to determine SO2 and CO2 mass emissions (tons) following 

the procedures in Appendices D and G, respectively. Further, the ARP requires the facility to possess SO2

allowances for each ton of SO2 emitted. The ARP also requires initial certification of required monitoring 

48 40 CFR 82.150
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systems within 90 days of commencement of commercial operation and the submittal of quarterly reports 

and an annual compliance certification. The ARP requirements are outlined in Section 7.9 and Attachment D 

of the Title V Permit No. 4911-149-0006-V-05-0. The proposed project will not alter any applicable 

requirements or compliance options of ARP to the OPC Chattahoochee operations. The facility will continue 

to maintain sufficient allowances under ARP for its operations.

4.8.2 Clean Air Interstate Rule / Cross-State Air Pollution Rule

The CAIR, 40 CFR 96, called for reductions in SO2 and NOX emissions by utilizing an emissions trading 

program. More broadly, 40 CFR 96 also includes a forerunner to CAIR, the NOX SIP Call / NOX Budget 

program, and the name of 40 CFR 96 (NOX Budget Trading Program for State Implementation Plans) still 

reflects the origins in regulating only NOX.

The CSAPR was developed to require affected states to reduce emissions from power plants that contribute 

to ozone and/or particulate matter emissions.49 Following legal challenges, CSAPR replaced CAIR50 and 

began Phase 1 implementation on January 1, 2015 for annual programs and May 1, 2015 for the ozone 

season program. Phase 2 implementation began on January 1, 2017 for annual programs and May 1, 2017 

for ozone season programs.

Therefore, since CSAPR is currently effective, potential applicability is evaluated against the CSAPR Program 

and not CAIR. CSAPR applicability is found in 40 CFR 97.404 and definitions in 40 CFR 97.402 and 

implemented via Georgia EPD through GRAQC 391-3-1-.02(12) – (13). Georgia is subject to CSAPR

programs for both fine particles (SO2 and annual NOX) and ozone (ozone season NOX).51

CSAPR applicability is similar but distinct from ARP, with applicability criteria and definitions per 

40 CFR 97.402.52 In general, CSAPR regulates fossil-fuel-fired boilers and combustion turbines serving, on 

any day starting November 15, 1990 or later, an electrical generator with a nameplate capacity exceeding 

25 MWe and producing power for sale. OPC Chattahoochee’s CCCTs are affected sources under this 

regulation, and the proposed project will not alter any applicable requirements or compliance options of 

CSAPR to the facility’s operations. OPC Chattahoochee will continue to maintain sufficient allowances under 

CSAPR for its operations.

4.9 State Regulatory Requirements

In addition to federal air regulations, GRAQC Chapter 393-3-1 establishes regulations applicable at the 

emission unit level (source specific) and at the facility level.53 This section reviews the source specific 

requirements for the proposed project and does not detail generally applicable requirements such as 

payment of permit fees.

49 http://www.epa.gov/airtransport/

50 EME Homer City Generation, L.P. v. U.S. EPA. U.S. Court of Appeals for the District of Columbia Circuit, No. 11-1302, 

decided October 23, 2014 (lifting stay of CSAPR).

51 https://www.epa.gov/airmarkets/map-states-covered-csapr 

52 CSAPR applicability and definitions are repeated in four separate subparts of 40 CFR 97, but each has identical definitions 

and applicability requirements. Subpart AAAAA (5A), which is for the NOX Annual program, is used in this discussion.

53 Current through rules and regulations filed through May 8, 2020. http://rules.sos.ga.gov/gac/391-3-1
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4.9.1 GRAQC 391-3-1-.02(2)(b) – Visible Emissions

Rule (b) limits the visible emissions from any emissions source not subject to some other visible emissions 

limitation under GRAQC 391-3-1-.02 to 40% opacity. Visible emissions testing may be required at the 

discretion of the Director. The combustion turbines at OPC Chattahoochee are subject to this regulation. 

The duct burners are subject to more stringent visible emissions standards through Rule 391-3-1-.02(2)(d) 

and are, therefore, not subject to Rule (b).

The combustion turbines fire pipeline-quality natural gas with emissions exhibiting minimal opacity; the 

firing of clean fuels in conjunction with proper operation ensures compliance with this rule. No applicable 

requirements per Rule (b) will be altered as a result of the proposed project. The opacity limitation for the 

combustion turbines is subsumed by the more stringent opacity limitation given in Condition 3.3.6.e of the 

current operating permit.

4.9.2 GRAQC 391-3-1-.02(2)(d) – Fuel-Burning Equipment

Rule (d) limits the PM emissions, visible emissions, and NOX emissions from fuel-burning equipment. The 

standards are applied based on installation date, the heat input capacity of the unit, and the fuel(s) 

combusted. The GRAQC define “fuel-burning equipment” as follows:54

“Fuel-burning equipment” means equipment the primary purpose of which is the 

production of thermal energy from the combustion of any fuel. Such equipment is 

generally that used for, but not limited to, heating water, generating or super 

heating steam, heating air as in warm air furnaces, furnishing process heat 

indirectly, through transfer by fluids or transmissions through process vessel walls.

The combustion turbines are used for the generation of electric power, not the production of thermal 

energy. Therefore, they do not meet the definition of fuel burning equipment. The duct burners do, 

however, meet this definition and are therefore subject to this rule.

The duct burners were installed or modified after January 1, 1972, making them subject to the PM 

standards for new units under 391-3-1-.02(2)(d)2. Since each duct burner has a heat input capacity of 

between 10 and 250 MMBtu/hr, each duct burner has a PM emission limit based on the following equation, 

where P is the PM emission limit (lb/MMBtu) and R is the unit’s heat input capacity (MMBtu/hr):55

P = 0.5 (

10

R

)

0.5

The PM emission limit will not change once the proposed modifications are complete. The PM emission limits 

for the duct burners are subsumed by the more stringent PM emission limit found in Condition 3.3.6.c of the 

current operating permit.

All fuel-burning equipment constructed after January 1, 1972 is subject to a visible emissions limit of 20% 

except for one six minute period per hour of not more than 27% opacity. This limit applies to the duct 

burners.56 The opacity limit will not change once the propose modifications are complete. The opacity 

limitation for the duct burners is subsumed by the more stringent opacity limitation given in Condition 

3.3.6.e of the current operating permit.

54 GRAQC 391-3-1-.01(cc)

55 GRAQC 391-3-1-.02(2)(d)2(ii)

56 GRAQC 391-3-1-.02(2)(d)3
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4.9.3 GRAQC 391-3-1-.02(2)(e) – Particulate Emissions from Manufacturing 

Processes

Rule (e), commonly known as the process weight rule, establishes PM limits where not elsewhere specified. 

As the duct burners are fuel-burning equipment, they are subject to a separate particulate limit per Rule (d). 

Combustion turbines are not subject to Rule (d) and historically have not been regulated by Rule (e). 

Therefore, the combustion turbines and duct burners at OPC Chattahoochee are not subject to this 

regulation.

4.9.4 GRAQC 391-3-1-.02(2)(g) – Sulfur Dioxide

Rule (g) limits the maximum sulfur content of any fuel combusted in a fuel-burning source, based on the 

heat input capacity. As this rule applies to fuel-burning sources, not “fuel-burning equipment,” this 

regulation presently applies to both the combustion turbines and the duct burners. For the duct burners, 

which have heat input capacities below 100 MMBtu/hr, the fuel sulfur content is limited to not more than 

2.5% by weight.57 For the combustion turbines, which have heat input capacities greater than 

100 MMBtu/hr, the fuel sulfur content is limited to not more than 3% by weight.58 The proposed project 

does not alter the applicable requirements of Rule (g), and OPC Chattahoochee will continue to comply with 

Rule (g). This limit is subsumed by the more stringent fuel sulfur limit under NSPS Subpart KKKK.

4.9.5 GRAQC 391-3-1-.02(2)(n) – Fugitive Dust

Rule (n) requires facilities to take reasonable precautions to prevent fugitive dust from becoming airborne. 

OPC Chattahoochee will continue to take the appropriate precautions to prevent fugitive dust from 

becoming airborne for any applicable equipment. 

4.9.6 GRAQC 391-3-1-.02(2)(tt) – VOC Emissions from Major Sources

Rule (tt) limits VOC emissions from facilities that are located in or near the original Atlanta 1-hour ozone 

nonattainment area. OPC Chattahoochee is not located within the geographic area covered by this rule and 

is, therefore, not subject to this regulation.59

4.9.7 GRAQC 391-3-1-.02(2)(uu) – Visibility Protection

Rule (uu) requires EPD to provide an analysis of a proposed major source or a major modification to an 

existing source’s anticipated impact on visibility in any federal Class I area to the appropriate Federal Land 

Manager (FLM). The proposed project does not represent a major modification as defined in GRAQC 391-3-

1-.02(2)(uu)6, and therefore is not subject to this regulation.

4.9.8 GRAQC 391-3-1-.02(2)(jjj) – NOX from Electric Utility Steam Generating 

Units

Rule (jjj) limits NOX emissions from coal-fired electric utility steam generating units with heat input capacity 

greater than 250 MMBtu/hr located in or near the original Atlanta 1-hour ozone nonattainment area. OPC 

Chattahoochee only combusts natural gas and is therefore not subject to Rule(jjj).

57 GRAQC 391-3-1-.02(2)(g)2

58 GRAQC 391-3-1-.02(2)(g)2

59 GRAQC 391-3-1-.02(2)(tt)3
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4.9.9 GRAQC 391-3-1-.02(2)(lll) – NOX from Fuel-Burning Equipment

Rule (lll) limits the NOX emissions from fuel-burning equipment with a maximum design heat input capacity 

between 10 and 250 MMBtu/hr that was installed or modified on or after May 1, 1999. While the duct 

burners are fuel-burning equipment of the correct size range, Rule (lll) specifically exempts duct burners 

associated with combined cycle gas turbines from regulation.60 Therefore, Rule (lll) does not apply to OPC 

Chattahoochee.

4.9.10 GRAQC 391-3-1-.02(2)(mmm) – NOX Emissions from Stationary Gas 

Turbines and Stationary Engines used to Generate Electricity

Rule (mmm) restricts NOX emissions from small combustion turbines located in or near the Atlanta 

nonattainment area that are used to generate electricity. The combustion turbines at OPC Chattahoochee 

exceed 25 MWe capacity, and are, therefore, not subject to Rule (mmm).61

4.9.11 GRAQC 391-3-1-.02(2)(nnn) – NOX Emissions from Large Stationary Gas 

Turbines

Rule (nnn) restricts NOX emissions from sources located in or near the original Atlanta 1-hour ozone 

nonattainment area. Specifically, these regulations limit NOX emissions from stationary gas turbines with 

nameplate capacity greater than 25 MWe used to generate electricity. OPC Chattahoochee is located in 

Heard County, which is one of the listed counties regulated under this rule.62

Affected sources permitted after April 1, 2000, such as OPC Chattahoochee’s combustion turbines, are 

generally subject to a NOX emissions limit of 6 ppmvd at 15% oxygen. However, Part 4 of Rule (nnn) states 

that the 6 ppmvd emission limit does not apply to individual sources subject to 391-3-1-.03(8)(c)15 (state 

NNSR requirements). Both of OPC Chattahoochee’s combustion turbines were subject to and underwent 

NOX NNSR permitting under 391-3-1-.03(8)(c)15, including a control technology review and the use of 

sufficient NOX emissions offsets, prior to the construction. As such, the NOX emission limit of Rule (nnn) 

does not apply.

4.9.12 GRAQC 391-3-1-.02(2)(rrr) – NOX from Small Fuel-Burning Equipment

Rule (rrr) specifies requirements for fuel-burning equipment with capacities of less than 10 MMBtu/hr that 

are located in or near the original Atlanta 1-hour ozone nonattainment area. OPC Chattahoochee does not 

operate any fuel-burning equipment with a heat input capacity less than 10 MMBtu/hr and is, therefore, not 

subject to this regulation.

4.9.13 GRAQC 391-3-1-.02(2)(sss) – Multipollutant Control for Electric Utility 

Steam Generating Units

Rule (sss) applies to certain large electric utility steam generating units listed within the rule. OPC 

Chattahoochee is not subject to this regulation, because none of its units are listed in the regulation.

60 GRAQC 391-3-1-.02(2)(lll)6(ii)

61 GRAQC 391-3-1-.02(2)(mmm)1

62 GRAQC 391-3-1-.02(2)(nnn)6
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4.9.14 GRAQC 391-3-1-.02(2)(uuu) – SO2 Emissions from Electric Utility Steam 

Generating Units

Rule (uuu) applies to certain large electric utility steam generating units listed within the rule. OPC 

Chattahoochee is not subject to this regulation, because none of its units are listed in the regulation.

4.9.15 GRAQC 391-3-1-.03(1) – Construction (SIP) Permitting

The proposed project will require physical modifications to complete the proposed upgrades. Emissions 

increases associated with the proposed project are above the de minimis construction permitting thresholds 

specified in GRAQC 391-3-1-.03(6)(i). Therefore, a construction permit application is necessary, and the 

appropriate forms are included in Appendix D. As noted in Question 7 on the SIP Air Permit Application in 

Appendix D, OPC has not relied on the exemption in Georgia Rule 391-3-1-.03(6)(i)(3) for any previous 

modifications to OPC Chattahoochee.

4.9.16 GRAQC 391-3-1-.03(10) – Title V Operating Permits

The potential emissions of certain pollutants exceed the major source thresholds established by Georgia’s 

Title V operating permit program. Therefore, OPC Chattahoochee is a Title V major source. The facility 

currently operates under Permit No. 4911-149-0006-V-05-0. This application represents a significant 

modification to the existing Title V operating permit; accordingly a GEOS application has been submitted to 

address Title V related permitting requirements. 

4.9.17 Incorporation of Federal Regulations by Reference

The following federal regulations are incorporated in the GRAQC by reference and were addressed 

previously in the application:

► GRAQC 391-3-1-.02(7) – PSD

► GRAQC 391-3-1-.02(8) – NSPS

► GRAQC 391-3-1-.02(9) – NESHAP

► GRAQC 391-3-1-.02(10) – Chemical Accident Prevention

► GRAQC 391-3-1-.02(11) – CAM

► GRAQC 391-3-1-.02(12) – CSAPR for Annual NOX

► GRAQC 391-3-1-.02(13) – CSAPR for Annual SO2

► GRAQC 391-3-1-.02(14) – CSAPR for Ozone Season NOX

► GRAQC 391-3-1-.03(10) – Title V Operating Permits

► GRAQC 391-3-1-.13 – ARP 

4.9.18 Non-Applicability of Other GRAQC

A thorough examination of the GRAQC applicability to the proposed project reveals many GRAQC that do 

not currently apply, will not apply once the proposed modifications are complete, and do not impose 

additional requirements on operations. Such GRAQC rules include those specific to a particular type of 

industrial operation which is not and will not be performed at OPC Chattahoochee or is not impacted by the 

proposed project.
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5. TOXICS IMPACT ANALYSIS

EPD regulates the TAP emissions through a program approved under the provisions of GRAQC 391-3-1-

.02(2)(a)3(ii). A TAP is defined as any substance that may have an adverse effect on public health, 

excluding any specific substance that is covered by a State or Federal ambient air quality standard. 

Procedures governing EPD’s review of toxic air pollutant emissions as part of air permit reviews are 

contained in EPD’s Guideline for Ambient Impact Assessment of Toxic Air Pollutant Emissions (Guideline).

63

5.1 Derivation of Facility-Wide Emission Rates

According to the Guideline, dispersion modeling should be completed for each potentially toxic pollutant 

which has quantifiable emission increases and for which the facility-wide potential emissions are above the 

Minimum Emission Rate (MER) provided in Appendix A of the Guideline. The Guideline infers that a pollutant 

is identified as a toxic pollutant if any of the following toxicity-determined values have been established for 

that pollutant:

► EPA Integrated Risk Information System (IRIS) reference concentration (RfC) or unit risk;

► Occupational Safety and Health Administration (OSHA) Permissible Exposure Limits (PEL);

► American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values (TLV);

► National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limits (REL); 

► Lethal Dose – 50% (LD50) Standards; and

► The Guideline specifies that the resources should be referenced in the priority schedule listed above to 

determine long-term and short-term acceptable ambient concentrations (AACs) based on the exposure 

limits that are provided.

Per the Guideline under “Procedures for Demonstrating Compliance with AAC,” the general procedure for 

determination of TAPs impact is a simple comparative method:

► When the facility-wide emission rate for a given TAP is below its respective MER established in the table 

in Appendix A, no further analysis is required for that TAP.

► When the facility-wide emission rate for a given TAP is above its respective MER established in the table 

in Appendix A, a toxic impact analysis for that TAP is required. 

Table 5-1 summarizes OPC Chattahoochee’s potential emission rates for individual TAPs and compares them 

to the respective MERs.

63 Guideline for Ambient Impact Assessment of Toxic Air Pollutant Emissions. Georgia Department of Natural Resources, 

Environmental Protection Division, Air Protection Branch, Revised, May, 2017.
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Table 5-1. OPC Chattahoochee TAP Emissions and Respective MERs

5.2 Determination of Toxic Air Pollutant Impact

Based on the comparison of OPC Chattahoochee’s emissions of individual TAPs to their respective MERs, 

multiple pollutants have emission rates above the MER; therefore, SCREEN3 (version 13043) was used to 

evaluate the short-term (1-hour) concentration average for each individual TAP exceeding its MER. The 

modeled 1-hour average concentration was then converted to concentrations in both shorter (15-minute) 

and longer-term (24-hour or annual, as applicable) averaging periods.

For each TAP requiring further analysis, the total emissions of the TAP from both of the facility’s CCCT 

stacks were conservatively modeled as being emitted from only one of the two stacks. This is conservative 

as this assumes perfect alignment of modeled impacts from both sources. The distance to the fence line 

between the two stacks have no eventual bearing on modeling results as the maximum modeled impacts 

were predicted well beyond the boundary area of the fence line. The stack parameters are included in 

Table 5-2.

Table 5-2. Stack Parameters

OPC Chattahoochee 

Annual

Emissions

OPC Chattahoochee 

Annual

Emissions1

Short Term Emission 

Rate2

Minimum Emission Rate

(MER)3

(tpy) (lb/yr) (g/s) (lb/yr) Above MER?

Arsenic 1.63E-04 0.33 4.69E-06 0.057 Yes

Ammonia 184 367,920 5.29E+00 24,333 Yes

Beryllium 9.79E-06 0.02 2.82E-07 0.97 No

Cadmium 8.97E-04 1.8 2.58E-05 1.35 Yes

Acrolein 1.00E-01 201 3.06E-03 4.87 Yes

Lead - - - - - - 5.84 No

1,3-Butadiene 6.75E-03 13.5 2.06E-04 7.30 Yes

Cobalt 6.85E-05 0.14 1.97E-06 11.7 No

Manganese 3.10E-04 0.62 8.92E-06 12.2 No

Selenium 1.96E-05 0.04 5.63E-07 23.4 No

Chromium 1.14E-03 2.3 3.29E-05 24.33 No

Benzene 1.90E-01 380 5.79E-03 31.6 Yes

Nickel 1.71E-03 3.4 4.93E-05 38.6 No

Barium 3.59E-03 7.2 1.03E-04 57.9 No

Mercury 2.12E-04 0.42 6.10E-06 73.0 No

Copper 6.94E-04 1.4 1.99E-05 117 No

Sulfuric Acid 1.14 2,276 3.46E-02 117 Yes

Formaldehyde 1.85 3,699 5.63E-02 267 Yes

Propylene Oxide 4.55E-01 910 1.39E-02 657 Yes

Naphthalene 2.09E-02 41.8 6.37E-04 730 No

Acetaldehyde 0.63 1,255 1.92E-02 1,107 Yes

Molybdenum 8.97E-04 1.8 2.58E-05 1,738 No

Xylenes 1.00 2,008 3.06E-02 24,333 No

Hexane 1.47 2,937 4.22E-02 170,331 No

1,4-Dichlorobenzene 9.79E-04 2.0 2.82E-05 194,664 No

Propane 1.3 2,611 3.76E-02 208,600 No

Ethylbenzene 0.50 1,004 1.53E-02 243,330 No

Pentane 2.1 4,243 6.10E-02 341,858 No

Toluene 2.04 4,084 6.23E-02 1,216,650 No

3. From EPD's Guideline for Ambient Impact Assessment of Toxic Air Pollutant Emissions, updated October 2018.

1. Annual Emissions (lb/yr) = Annual Emissions (ton/yr) * 2,000 lb/ton.

2. Short Term Emission Rate (g/s) = Short Term Emissions (lb/hr) * 453.592 (g/lb) / 3,600 (s/hr)

Toxic Air Pollutant (TAP)

Source Type

Height

(m)

Diameter

(m)

Velocity

(m/s)

Gas Temperature

(K)

Point 39.624 5.03 24.81 366.2
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The rural option of SCREEN3 was used, as is specified in the SCREEN3 modeling files. A single SCREEN3 run 

was conducted using an emission rate of 1 gram per second (g/s). The 1-hour maximum impact at the 

fence line generated from SCREEN3 was adjusted using the multiplying factors in the Guideline to obtain the 

estimated maximum impacts for the 15-minute, 24-hour, and annual averaging periods. The modeling 

results at 1 g/s are included in Table 5-3.

Table 5-3. SCREEN3 Modeling Results at 1 g/s

The modeled impact for each averaging period was then scaled from an emission rate of 1 g/s to the 

facility-wide emission rate of each pollutant, assuming all facility-wide emissions are emitted from the “worst 

case” of the facility’s two stacks and that the modeled impact is directly proportional to the mass emission 

rate. As shown in Table 5-4, the impacts of all TAP from OPC Chattahoochee are well below the respective

annual, 24-hour, and 15-minute AACs. The SCREEN3 modeling file and TAP emission calculations are 

included in Appendix C of this application.

Maximum 1-Hour Impact 1.007 μg/m3

Maximum 15-Minute Impact1

1.329 μg/m3

Maximum 24-Hour Impact20.532 μg/m3

Maximum Annual Impact3

0.043 μg/m3

1. The 15-minute impact equals the 1-hour impact times 1.32 per the 

EPD Guideline .

2. The 24-hour impact equals the 1-hour impact times 0.4 per the

EPD Guideline .

3. The annual impact equals the 1-hour impact times 0.08 per the

EPD Guideline .
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Table 5-4. Modeling Results Compared to AAC Values

Maximum

Annual Impact Annual AAC

Maximum

24-Hour Impact 24-Hour AAC

Maximum

15-Minute Impact 15-Minute AAC

μg/m3 μg/m3 % of AAC μg/m3 μg/m3 % of ACC μg/m3 μg/m3 % of AAC

Arsenic 2.00E-07 2.33E-04 < 1.00% N/A N/A - - 6.24E-06 2.00E-01 < 1.00%

Ammonia 2.25E-01 1.00E+02 < 1.00% N/A N/A - - 7.03E+00 2.40E+03 < 1.00%

Cadmium 1.10E-06 5.56E-03 < 1.00% N/A N/A - - 3.43E-05 3.00E+01 < 1.00%

Acrolein 1.30E-04 2.00E-02 < 1.00% N/A N/A - - 4.07E-03 2.30E+01 < 1.00%

1,3-Butadiene 8.76E-06 3.00E-02 < 1.00% N/A N/A - - 2.74E-04 1.10E+03 < 1.00%

Benzene 2.46E-04 1.30E-01 < 1.00% N/A N/A - - 7.70E-03 1.60E+03 < 1.00%

Sulfuric Acid N/A N/A - - 1.84E-02 2.40E+00 < 1.00% 4.60E-02 3.00E+02 < 1.00%

Formaldehyde 2.40E-03 1.10E+00 < 1.00% N/A N/A - - 7.49E-02 2.45E+02 < 1.00%

Propylene Oxide 5.91E-04 2.70E+00 < 1.00% N/A N/A - - N/A N/A - -

Acetaldehyde 8.15E-04 4.55E+00 < 1.00% N/A N/A - - 2.55E-02 4.50E+03 < 1.00%

1. AAC values from the EPD Guideline, updated October 2018.

Toxic Air Pollutant (TAP)
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APPENDIX A. AREA MAP AND PROCESS FLOW DIAGRAM
680,000 681,000 682,000 683,000 684,000

3,696,000

3,697,000

3,698,000

3,699,000

3,700,000

3,701,000

Georgia Alabama

Tennessee

Florida

South Carolina

Approximate Facility Location

Figure A-1. Facility Area Map

Oglethorpe Power Corporation

Chattahoochee Energy Facility

Franklin, Heard County, Georgia

UTM Easting (m)

UTM Northing (m)

Coordinates reflect UTM projection Zone 16, NAD83.
201101.0056

June 2020

Oglethorpe Power Corporation 

Chattahoochee Energy Facility

Franklin, Georgia

Figure A-2. Process Flow Diagram

Legend

Material Flow

Air Emissions

SCR8A Air Pollution Control Device

CT8A Process Unit

Combustion 

Turbine 8A 

(CT8A)

Natural Gas

Electricity

Heat Recovery 

Steam Generator 8A 

and Duct Burner 8A 

(DB8A)

Natural Gas

Combustion 

Turbine 8B 

(CT8B)

Natural Gas

Electricity

Heat Recovery 

Steam Generator 8B 

and Duct Burner 8B 

(DB8B)

Natural Gas

Steam Turbine Electricity

ST8B

SCR8B

CO8B

ST8A

SCR8A

CO8A
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APPENDIX B. EMISSION CALCULATIONS
Appendix B - Potential to Emit Calculations

Oglethorpe Power Corporation - Chattahoochee Energy Facility

Table B-1. Natural Gas Burning Equipment - Operating Parameters - Design Capacity

Maximum Annual 

Operating Capacity1

Potential Annual 

Operation 

Emission Source Source No. Fuel Type (Million MMBtu/yr) (hr/yr)

CCCT8A CT8A and DB8A Natural Gas 16.5 8,760

CCCT8B CT8B and DB8B Natural Gas 16.5 8,760

Table B-2. CCCT Potential Criteria Pollutant Emissions

Emission Factor Potential Emissions10

Pollutant (lb/MMBtu) (tpy)

NOX

1 1.11E-02 179.6

CO2 4.48E-03 86.0

VOC3 2.59E-03 43

PM4 9.91E-03 164

Total PM10

4 9.91E-03 164

Total PM2.5

4 9.91E-03 164

SO2

5 6.00E-04 9.91

H2SO4

6 6.89E-05 1.14

CO2

7 1.19E+02 1,963,369

CH4

8 2.20E-03 36.4

N2O8 2.20E-04 3.64

CO2e9 1.19E+02 1,965,365

 Pollutant GWP

 CO2 1

 CH4 25

 N2O 298

1. Based on post project heat input capacity per turbine at 59F (1,790.7 MMBtu/hr) and the permitted heat input capacity for the duct burners (95 

MMBtu/hr) times potential operation of 8,760 hrs/yr.

3. VOC emission factor based on 2.0 ppm @ 15% O2 existing BACT limit.

1. Emission factor for NOX based on 3.0 ppm @ 15% O2 existing BACT limit. Permit Condition 

3.3.4 limits NOX emissions to 179.6 tpy (total from all CCCTs).

2. Emission factor for CO based on 2.0 ppm @ 15% O2 existing BACT limit. Permit Condition 

3.3.5 limits CO emissions to 86 tpy (total from all CCCTs).

10. Potential Emissions (tpy) = Emission Factor (lb/MMBtu) * Maximum Annual Operating 

Capacity (Million MMBtu/yr) * 1E6 MMBtu/ Million MMBtu / 2,000 lb/ton

4. Condition 3.3.6.c limits PM to 0.011 lb/MMBtu, LHV basis. The limit was adjusted to HHV 

basis using a HHV/LHV ratio of 1.109805, consistent with the ratio used by Siemens in its 

performance data sheet for TPU1 dated 1/12/2020. It was conservatively assumed all PM is 

less than 2.5 microns in diameter (i.e., PM2.5 = PM10 = PM).

5. SO2 emissions were estimated using the default SO2 emission rate for pipeline natural gas 

from 40 CFR 75, Appendix D, Section 2.3.1.1, consistent with the methodology used to report 

the facility's SO2 emissions under the CAMD programs.

6. H2SO4 emissions were calculated assuming a 7.5% conversion of SO2 to H2SO4, consistent 

with the facility's initial November 2000 PSD permit application.

7. CO2 emissions were calculated in accordance with 40 CFR 75, Appendix G, Equation G-4 

using the F-factor for natural gas, consistent with the methodology used to report the facility's 

CO2 emissions under the CAMD programs and the EPA GHG reporting rule.

8. CH4 and N2O emission factors for natural gas combustion are from 40 CFR 98, Subpart C, 

Table C-2, converted from kg to lb, consistent with the methodology used to report the 

facility's emissions under the EPA GHG reporting rule.

9. Total GHG emissions in CO2e is the sum of the product of each GHG and its respective 

global warming potential (GWP) per 40 CFR Part 98 Subpart A, Table A-1, effective January 1, 

2014.

Gas Burning Equipment Criteria Trinity Consultants Page 1 of 4
Appendix B - Potential to Emit Calculations

Oglethorpe Power Corporation - Chattahoochee Energy Facility

Table B-3. Natural Gas Burning Equipment - Operating Parameters - Design Capacity

Maximum Annual 

Operating Capacity1

Potential Annual 

Operation 

Emission Source Source No. Fuel Type (Million MMBtu/yr) (hr/yr)

CT8A Combustion Turbine CT8A Natural Gas 15.69 8,760

CT8B Combustion Turbine CT8B Natural Gas 15.69 8,760

DB8A Duct Burner DB8A Natural Gas 0.83 8,760

DB8B Duct Burner DB8B Natural Gas 0.83 8,760

Table B-4. Combustion Turbines Potential HAP Emissions

Potential Emissions2

Combustion Turbines

Pollutant (lb/MMBtu) (tpy)

Lead -- --

1,3-Butadiene 4.30E-07 6.75E-03

Acetaldehyde 4.00E-05 6.27E-01

Acrolein 6.40E-06 1.00E-01

Benzene 1.20E-05 1.88E-01

Ethylbenzene 3.20E-05 5.02E-01

Formaldehyde3 1.14E-04 1.79

Naphthalene 1.30E-06 2.04E-02

Propylene Oxide 2.90E-05 4.55E-01

Toluene 1.30E-04 2.04

Xylenes 6.40E-05 1.00E+00

Total HAP4 4.29E-04 6.73

Max Single HAP5 1.30E-04 2.04

4. Total HAP emission factor is the sum of all speciated HAP emission factors.

5. Largest HAP from combustion turbines is formaldehyde.

Table B-5. Potential HAP Emissions from Duct Burners

Potential Emissions2

Pollutant (lb/MMscf) (tpy)3

2-Methylnapthalene 2.40E-05 1.96E-05

3-Methylchloranthrene 1.80E-06 1.47E-06

1.60E-05 1.31E-05

Acenaphthene 1.80E-06 1.47E-06

Acenaphthylene 1.80E-06 1.47E-06

Anthracene 2.40E-06 1.96E-06

Benz(a)anthracene 1.80E-06 1.47E-06

Benzene 2.10E-03 1.71E-03

Benzo(a)pyrene 1.20E-06 9.79E-07

Benzo(b)fluoranthene 1.80E-06 1.47E-06

Benzo(g,h,i)perylene 1.20E-06 9.79E-07

Benzo(k)fluoranthene 1.80E-06 1.47E-06

Chrysene 1.80E-06 1.47E-06

Dibenzo(a,h)anthracene 1.20E-06 9.79E-07

1,4-Dichlorobenzene 1.20E-03 9.79E-04

Fluoranthene 3.00E-06 2.45E-06

Fluorene 2.80E-06 2.28E-06

Formaldehyde 7.50E-02 6.12E-02

Hexane 1.80E+00 1.47

Indeno(1,2,3-cd)pyrene 1.80E-06 1.47E-06

Naphthalene 6.10E-04 4.98E-04

Phenanathrene 1.70E-05 1.39E-05

Pyrene 5.00E-06 4.08E-06

Toluene 3.40E-03 2.77E-03

Arsenic 2.00E-04 1.63E-04

Beryllium 1.20E-05 9.79E-06

Cadmium 1.10E-03 8.97E-04

Chromium 1.40E-03 1.14E-03

Cobalt 8.40E-05 6.85E-05

Manganese 3.80E-04 3.10E-04

Mercury 2.60E-04 2.12E-04

Nickel 2.10E-03 1.71E-03

Selenium 2.40E-05 1.96E-05

Total HAP3 1.89 1.54

Max Single HAP4 1.80 1.47

1. Emission factors per AP-42, Section 1.4 Natural Gas Combustion, Tables 1.4-3 and 1.4-4.

3. Total HAP emission factor is the sum of all speciated HAP emission factors.

4. Max single HAP from duct burners is hexane.

1. Based on post project heat input capacity per turbine at 59F (1,790.7 MMBtu/hr) and the permitted heat input capacity for the duct burners (95 MMBtu/hr) times 

potential operation of 8,760 hrs/yr.

2. Potential Emissions (tpy) = Emission Factor (lb/MMscf) / 1,020 (MMBtu/MMscf) * Maximum Annual Operating Capacity (Million 

MMBtu/yr) * 1E6 MMBtu/ Million MMBtu / 2,000 lb/ton 

Emission Factor1

7,12-Dimethylbenz(a)anthracene

Emission Factor1

2. Potential Emissions (tpy) = Emission Factor (lb/MMBtu) * Maximum Annual Operating Capacity 

(Million MMBtu/yr) * 1E6 MMBtu/ Million MMBtu / 2,000 lb/ton

1. Emission factors per AP-42, Section 3.1 Stationary Gas Turbines, Tables 3.1.-2a and 3.1-3 unless 

otherwise noted.

3. Formaldehyde emission factor based on AP-42 Section 3.1 Database (April 2000) for Frame Type 

CTs greater than 40 MW.

Gas Burning Equipment HAP Trinity Consultants Page 2 of 4
Appendix B - Potential to Emit Calculations

Oglethorpe Power Corporation - Chattahoochee Energy Facility

Table B-6. Cooling Tower Potential Emissions

Drift Loss Flow1

Total Dissolved 

Solids2

(gpm) (mg/L) (lb/hr) (tpy) (lb/hr) (tpy) (lb/hr) (tpy)

Cooling Tower 7.03 602 2.12 9.28 2.02 8.87 4.54E-01 1.99

1. Based on cooling tower system operational data from Siemens.

2. Based on facility operational data.

3. Hourly PM emission rate (lb/hr) = Flow rate (gal/min) × TDS (mg/L) × 3.78541 (L/gal) × 2.2045E-06 (lb/mg) x 60 min/hr

4. Annual PM emission rate (ton/yr) = Hourly emission rate (lb/hr) × 8,760 (hours/yr)/2,000 (lb/ton).

Table B-7. Derivation of PM10/PM2.5 Fraction1

Drift Droplet 

Diameter 

(Dd)

Drift Droplet 

Volume2

(Vdroplet)

Drift Droplet 

Mass3

(Mdroplet)

Droplet Particle 

Mass4

 (MTDS)

Solid Particle 

Diameter5

(DTDS)

EPRI 

Cumulative 

% Mass 

Smaller6

Interpolation 

Value for 

PM2.5

7

Interpolation 

Value for 

PM10

7

(μm) (μm3) (μg) (μg) (μm) (%) (%) (%)

0 0.00E+00 0.00E+00 0.00E+00 0.000 0 -- --

10 5.24E+02 5.24E-04 5.24E-08 0.357 0 -- --

20 4.19E+03 4.19E-03 4.19E-07 0.714 0.196 -- --

30 1.41E+04 1.41E-02 1.41E-06 1.071 0.226 -- --

40 3.35E+04 3.35E-02 3.35E-06 1.428 0.514 -- --

50 6.54E+04 6.54E-02 6.54E-06 1.784 1.816 -- --

60 1.13E+05 1.13E-01 1.13E-05 2.141 5.702 -- --

70 1.80E+05 1.80E-01 1.80E-05 2.498 21.348 -- --

90 3.82E+05 3.82E-01 3.82E-05 3.212 49.812 21.421 --

110 6.97E+05 6.97E-01 6.97E-05 3.926 70.509 -- --

130 1.15E+06 1.15E+00 1.15E-04 4.639 82.023 -- --

150 1.77E+06 1.77E+00 1.77E-04 5.353 88.012 -- --

180 3.05E+06 3.05E+00 3.05E-04 6.424 91.032 -- --

210 4.85E+06 4.85E+00 4.85E-04 7.495 92.468 -- --

240 7.24E+06 7.24E+00 7.24E-04 8.565 94.091 -- --

300 1.41E+07 1.41E+01 1.41E-03 10.706 96.288 -- 95.563

350 2.24E+07 2.24E+01 2.24E-03 12.491 97.011 -- --

400 3.35E+07 3.35E+01 3.35E-03 14.275 98.34 -- --

450 4.77E+07 4.77E+01 4.77E-03 16.060 99.071 -- --

600 1.13E+08 1.13E+02 1.13E-02 21.413 100 -- --

2. Vdroplet = 4/3 π (Dd /2)3 [Equation 2 of the Document]

3. Mdroplet = density (ρw) of water * Vdroplet = ρw * 4/3 π (Dd /2)3 

ρw = 1.00E-06 μg/μm3

4. MTDS = TDS * Mdroplet [Equation 3 of the Document, with TDS in units of ppm]

TDS = 100 mg/L Total Dissolved Solids Per Table B-6

TDS = 100 ppm

5. MTDS = (ρTDS) (VTDS) = (ρTDS) (4/3)π (DTDS /2)3

 [Equation 5 of the Document]

Therefore, the equation can be solved for DTDS: DTDS = {MTDS/[(ρTDS)* 4/3 * π]}1/3 × 2

Assume solid particulates have the same density (ρTDS) as sodium chloride per the Document: 2.20E-06 μg/μm3

Total PM2.5 Emissions5

Emission Source

Filterable PM Emissions3,4 Total PM10 Emissions5

Assumptions/helpful equations

Volume of a sphere = 4 π r3

/3

1. Based on the methodology discussed in "Calculating Realistic PM10 Emissions from Cooling Towers" by Joel Reisman and Gordon Frisbie, 2002 (the Document).

https://yosemite.epa.gov/r9/air/epss.nsf/6924c72e5ea10d5e882561b100685e04/44841bd36885b15e882579f80062a144/$FILE/Cooling%20Tower%20PM%20Emissions.pdf

6. Based on drift eliminator test data from a test conducted by Environmental Systems Corporation (ESC) at the Electric Power Research Institute (EPRI) test facility in Houston, 

Texas in 1988 (Aull, 1999) as documented in Table 1 of the Document. 

7. DTDS represents the particle size of collected material in droplet. The EPRI cumulative % mass smaller indicates the percentage of material in that specific water droplet size that 

has a diameter smaller than DTDS. Therefore, linear interpolation between calculated DTDS is necessary to ascertain the specific mass percentages to estimate PM10 and PM2.5 

emissions. For example, at 1,000 mg/L TDS: 

%MassPM10 = %Mass Less than 10 DTDS + [ (10 - DTDS Less Than 10) / (DTDS Greater Than 10 - DTDS Less Than 10) ] * (%Mass Greater than 10 DTDS -

%Mass Less than 10 DTDS)

i.e. 82.041% = 82.023% + [ (10 - 9.995) / (11.533 - 9.995) ] * (88.012% - 82.023%)

5. PM10 and PM2.5 emissions are estimated based on the particulate size distribution below, interpolated from data in Calculating Realistic PM 10 Emissions from Cooling Towers by Joel Reisman 

and Gordon Frisbie, 2002. Detailed derivation of PM10/PM2.5 fractions are discussed in Table B-7. 

Cooling Towers Trinity Consultants Page 3 of 4
Appendix B - Potential to Emit Calculations

Oglethorpe Power Corporation - Chattahoochee Energy Facility

Table B-8. Site-wide Potential to Emit

Potential Emissions

Pollutant (tpy)

NOX 179.6

CO 86.0

VOC 42.8

PM 173

Total PM10 173

Total PM2.5 166

SO2 9.91

H2SO4 1.14

CO2 1,963,369

CH4 36.4

N2O 3.64

CO2e 1,965,365

Total HAP 8.27

Max Single HAP1 2.10

1. Maximum single HAP is Formaldehyde.

PTE Trinity Consultants Page 4 of 4
Appendix B - New Source Review Calculations

Oglethorpe Power Corporation - Chattahoochee Energy Facility

Table B-9. Emission Factors for NSR Analysis

Pollutant

Emission 

Factor

(lb/MMBtu)

VOC1

1.00E-03

PM10/PM2.5

2

6.00E-03

SO2

3

6.00E-04

H2SO4

4

6.89E-05

CO2

5

118.86

CH4

6

2.20E-03

N2O

6

2.20E-04

CO2e

7

118.98

where:

Cgas, VOC as CH4 = 0.596

MWVOC as CH4 = 16.043 lb/lb-mol, molecular weight of CH4

Cgas, HCHO = 0.061

MWHCHO = 30.026

Fd = 8,710

%O2 = 15

CO2: 1

CH4: 25

N2O: 298

1. VOC emissions were based on the most recent facility compliance testing data. The total VOC emission factor was calculated as the sum 

of the 2005 VOC as CH4 (Method 25A) test results and the 2003 formaldehyde (Method 0011) test results. A 10% safety factor was 

conservatively applied to the stack test results. The emissions concentrations (ppm @ 15% O2) were converted to emission factors 

(lb/MMBtu) using the following equation:

ppmv, maximum VOC as CH4 test result for either unit at any load

dscf/MMBtu, natural gas fuel factor from 40 CFR 60, Method 19, Table 19-2

lb/MMBtu = (Cgas, VOC as CH4 * MWVOC as CH4 + Cgas, HCHO * MWHCHO) * Fd * 2.59E-9 * 20.9 / (20.9 - %O2)

2. PM emissions are based on the average of the 2003 compliance testing results for units 8A (0.0069 lb/MMBtu) and 8B (0.0051 

lb/MMBtu). The 2003 testing was inclusive of both the filterable and condensable portions of PM. It was conservatively assumed all PM is 

less than 2.5 microns in diameter (i.e., PM2.5 = PM10 = PM).

3. SO2 emissions were estimated using the default SO2 emission rate for pipeline natural gas from 40 CFR 75, Appendix D, Section 2.3.1.1, 

consistent with the methodology used to report the facility's SO2 emissions under the CAMD programs.

4. H2SO4 emissions were calculated assuming a 7.5% conversion of SO2 to H2SO4, consistent with the facility's initial November 2000 PSD 

permit application.

5. CO2 emissions were calculated in accordance with 40 CFR 75, Appendix G, Equation G-4 using the F-factor for natural gas, consistent 

with the methodology used to report the facility's CO2 emissions under the CAMD programs and the EPA GHG reporting rule.

7. CO2e was calculated as the sum of the emission factor for each GHG pollutant multiplied by that pollutant's global warming potential 

(GWP). GWPs were taken from 40 CFR 98, Subpart A, Table A-1:

ppmv, maximum HCHO test result for either unit at any load

lb/lb-mol, molecular weight of HCHO

%, corrected basis for exhaust gas O2 content

6. CH4 and N2O emission factors for natural gas combustion are from 40 CFR 98, Subpart C, Table C-2, converted from kg to lb, consistent 

with the methodology used to report the facility's emissions under the EPA GHG reporting rule.

EFs Trinity Consultants Page 1 of 9
Appendix B - New Source Review Calculations

Oglethorpe Power Corporation - Chattahoochee Energy Facility

Table B-10. Past Actual Emissions - Unit 8A

NOX

2 CO CO3

VOC PM10/PM2.5 SO2 H2SO4 CO2e

Jul-15 1,020,758 5.0 0.33 0.33 0.51 3.1 0.31 0.04 60,724

Aug-15 994,411 5.2 0.95 0.95 0.50 3.0 0.30 0.03 59,157

Sep-15 764,809 4.8 1.50 1.50 0.38 2.3 0.23 0.03 45,498

Oct-15 1,045,517 5.3 0.78 0.78 0.52 3.1 0.31 0.04 62,197

Nov-15 594,288 3.2 2.28 1.33 0.30 1.8 0.18 0.02 35,354

Dec-15 912,953 4.4 3.31 2.04 0.46 2.7 0.27 0.03 54,311

Jan-16 1,082,755 4.7 3.01 2.42 0.54 3.2 0.32 0.04 64,412

Feb-16 687,197 3.2 2.03 1.54 0.34 2.1 0.21 0.02 40,881

Mar-16 237,308 1.1 0.11 0.11 0.12 0.7 0.07 0.01 14,117

Apr-16 3,242 0.2 0.30 0.01 0.00 0.0 0.00 0.00 193

May-16 1,159,578 4.8 0.95 0.95 0.58 3.5 0.35 0.04 68,982

Jun-16 1,058,882 4.3 0.55 0.55 0.53 3.2 0.32 0.04 62,992

Jul-16 1,092,489 4.1 1.13 1.13 0.55 3.3 0.33 0.04 64,991

Aug-16 1,121,686 4.3 1.34 1.34 0.56 3.4 0.34 0.04 66,728

Sep-16 1,076,934 4.3 1.20 1.20 0.54 3.2 0.32 0.04 64,066

Oct-16 1,166,258 4.1 0.92 0.92 0.58 3.5 0.35 0.04 69,380

Nov-16 412,349 1.6 0.65 0.65 0.21 1.2 0.12 0.01 24,530

Dec-16 1,017,572 4.8 0.47 0.47 0.51 3.1 0.31 0.04 60,534

Jan-17 1,139,725 5.2 0.22 0.22 0.57 3.4 0.34 0.04 67,801

Feb-17 1,053,333 4.7 0.13 0.13 0.53 3.2 0.32 0.04 62,662

Mar-17 823,350 3.7 0.10 0.10 0.41 2.5 0.25 0.03 48,980

Apr-17 784,288 3.5 1.29 1.29 0.39 2.4 0.24 0.03 46,656

May-17 1,081,582 4.4 1.35 1.35 0.54 3.2 0.32 0.04 64,342

Jun-17 1,074,670 4.6 1.06 1.06 0.54 3.2 0.32 0.04 63,931

Jul-17 1,154,981 4.9 0.87 0.87 0.58 3.5 0.35 0.04 68,709

Aug-17 1,113,454 4.8 1.01 1.01 0.56 3.3 0.33 0.04 66,238

Sep-17 1,116,481 4.4 0.73 0.73 0.56 3.3 0.33 0.04 66,418

Oct-17 1,191,038 4.7 0.52 0.52 0.60 3.6 0.36 0.04 70,854

Nov-17 704,062 3.2 0.51 0.51 0.35 2.1 0.21 0.02 41,884

Dec-17 975,918 3.9 0.34 0.34 0.49 2.9 0.29 0.03 58,056

Jan-18 1,029,711 3.9 0.62 0.62 0.52 3.1 0.31 0.04 61,256

Feb-18 934,663 3.7 0.51 0.51 0.47 2.8 0.28 0.03 55,602

Mar-18 273,177 1.3 0.37 0.37 0.14 0.8 0.08 0.01 16,251

Apr-18 962,750 4.4 0.92 0.92 0.48 2.9 0.29 0.03 57,273

May-18 1,037,073 4.7 0.72 0.72 0.52 3.1 0.31 0.04 61,694

Jun-18 995,806 3.8 0.46 0.46 0.50 3.0 0.30 0.03 59,240

Jul-18 1,129,935 3.4 0.10 0.10 0.57 3.4 0.34 0.04 67,219

Aug-18 1,030,553 3.3 0.79 0.79 0.52 3.1 0.31 0.04 61,307

Sep-18 1,083,855 2.9 0.46 0.46 0.54 3.3 0.33 0.04 64,477

Oct-18 188,835 0.5 0.05 0.05 0.09 0.6 0.06 0.01 11,234

Nov-18 315,838 1.5 0.48 0.48 0.16 0.9 0.09 0.01 18,789

Dec-18 915,394 3.8 1.22 1.22 0.46 2.7 0.27 0.03 54,456

Jan-19 1,075,633 4.0 0.82 0.82 0.54 3.2 0.32 0.04 63,988

Feb-19 920,427 4.0 0.57 0.57 0.46 2.8 0.28 0.03 54,755

Mar-19 708,361 3.5 0.59 0.59 0.35 2.1 0.21 0.02 42,140

Apr-19 1,033,526 5.0 0.84 0.84 0.52 3.1 0.31 0.04 61,483

May-19 1,049,466 5.1 0.36 0.36 0.53 3.1 0.31 0.04 62,432

Jun-19 1,005,922 4.9 0.35 0.35 0.50 3.0 0.30 0.03 59,841

Jul-19 1,121,571 5.1 0.11 0.11 0.56 3.4 0.34 0.04 66,721

Aug-19 1,125,943 5.1 0.24 0.24 0.56 3.4 0.34 0.04 66,981

Sep-19 1,016,000 4.8 0.94 0.94 0.51 3.0 0.30 0.03 60,441

Oct-19 760,008 3.8 0.53 0.53 0.38 2.3 0.23 0.03 45,212

Nov-19 895,090 4.3 0.73 0.73 0.45 2.7 0.27 0.03 53,248

Dec-19 816,265 4.0 0.75 0.75 0.41 2.4 0.24 0.03 48,559

Maximum 1,191,038 5.3 3.31 2.42 0.60 3.6 0.36 0.04 70,854

Month1

Monthly Emissions (tons/mo)

1. A five-year lookback period is allowed for determining baseline actual emissions for existing electric utility steam generating units, per 40 CFR 

52.21(b)(48)(i).

Monthly Heat 

Input 

(MMBtu/mo)2

3. Per the facility's quarterly Title V monitoring reports to the Georgia EPD. If the monthly average CO emission rate, based on the reported CO 

emissions divided by the heat input for the month, exceeded the facility's permitted CO emission limit of 2.0 ppmvd @ 15% O2 (equivalent to 

0.00448 lb/MMBtu), the CO emissions for that month were re-calculated using the CO emission limit multiplied by the monthly heat input.

2. Per the facility's quarterly Part 75 emissions reports to EPA submitted through the Emissions Collection and Monitoring Plan System (ECMPS).

8A Trinity Consultants Page 2 of 9
Appendix B - New Source Review Calculations

Oglethorpe Power Corporation - Chattahoochee Energy Facility

Table B-11. Past Actual Emissions - Unit 8B

NOX

2 CO CO3

VOC PM10/PM2.5 SO2 H2SO4 CO2e

Jul-15 980,457 5.0 0.39 0.39 0.49 2.9 0.29 0.03 58,326

Aug-15 847,397 4.9 0.79 0.79 0.42 2.5 0.25 0.03 50,411

Sep-15 777,710 4.2 0.88 0.88 0.39 2.3 0.23 0.03 46,265

Oct-15 1,146,414 5.3 0.12 0.12 0.57 3.4 0.34 0.04 68,199

Nov-15 482,136 2.6 1.35 1.08 0.24 1.4 0.14 0.02 28,682

Dec-15 847,320 4.0 2.80 1.90 0.42 2.5 0.25 0.03 50,406

Jan-16 1,019,484 4.4 1.30 1.30 0.51 3.1 0.31 0.04 60,648

Feb-16 823,430 3.9 1.79 1.79 0.41 2.5 0.25 0.03 48,985

Mar-16 173,325 0.7 0.07 0.07 0.09 0.5 0.05 0.01 10,311

Apr-16 1,119,416 5.0 0.28 0.28 0.56 3.4 0.34 0.04 66,593

May-16 1,115,034 5.3 0.34 0.34 0.56 3.3 0.33 0.04 66,332

Jun-16 1,094,115 5.2 0.18 0.18 0.55 3.3 0.33 0.04 65,088

Jul-16 1,125,967 5.1 0.71 0.71 0.56 3.4 0.34 0.04 66,983

Aug-16 1,146,152 5.0 1.03 1.03 0.57 3.4 0.34 0.04 68,183

Sep-16 1,112,597 4.7 0.69 0.69 0.56 3.3 0.33 0.04 66,187

Oct-16 1,139,979 4.5 0.88 0.88 0.57 3.4 0.34 0.04 67,816

Nov-16 410,026 1.8 0.77 0.77 0.21 1.2 0.12 0.01 24,392

Dec-16 1,038,385 5.4 0.39 0.39 0.52 3.1 0.31 0.04 61,772

Jan-17 1,192,710 5.9 0.06 0.06 0.60 3.6 0.36 0.04 70,953

Feb-17 1,022,803 5.1 0.16 0.16 0.51 3.1 0.31 0.04 60,845

Mar-17 835,857 4.1 0.03 0.03 0.42 2.5 0.25 0.03 49,724

Apr-17 767,267 3.5 0.59 0.59 0.38 2.3 0.23 0.03 45,644

May-17 938,190 4.2 0.76 0.76 0.47 2.8 0.28 0.03 55,812

Jun-17 1,042,315 4.7 0.25 0.25 0.52 3.1 0.31 0.04 62,006

Jul-17 1,141,857 4.7 0.14 0.14 0.57 3.4 0.34 0.04 67,928

Aug-17 1,117,579 4.2 0.28 0.28 0.56 3.4 0.34 0.04 66,484

Sep-17 1,083,175 3.6 0.16 0.16 0.54 3.2 0.32 0.04 64,437

Oct-17 1,000,852 3.8 0.67 0.67 0.50 3.0 0.30 0.03 59,540

Nov-17 660,925 2.8 0.52 0.52 0.33 2.0 0.20 0.02 39,318

Dec-17 914,097 4.0 0.41 0.41 0.46 2.7 0.27 0.03 54,379

Jan-18 903,676 4.1 1.28 1.28 0.45 2.7 0.27 0.03 53,759

Feb-18 646,904 3.5 1.07 1.07 0.32 1.9 0.19 0.02 38,484

Mar-18 485,561 2.6 0.83 0.83 0.24 1.5 0.15 0.02 28,886

Apr-18 1,033,060 4.7 0.38 0.38 0.52 3.1 0.31 0.04 61,456

May-18 1,062,566 4.4 0.38 0.38 0.53 3.2 0.32 0.04 63,211

Jun-18 779,147 3.2 0.43 0.43 0.39 2.3 0.23 0.03 46,351

Jul-18 1,134,523 4.5 0.16 0.16 0.57 3.4 0.34 0.04 67,492

Aug-18 1,080,287 4.4 0.36 0.36 0.54 3.2 0.32 0.04 64,265

Sep-18 482,136 2.0 0.15 0.15 0.24 1.4 0.14 0.02 28,682

Oct-18 0 0 0 0 0 0 0 0 0

Nov-18 575,142 3.0 1.39 1.29 0.29 1.7 0.17 0.02 34,215

Dec-18 976,385 4.1 0.40 0.40 0.49 2.9 0.29 0.03 58,084

Jan-19 987,705 3.9 0.35 0.35 0.49 3.0 0.30 0.03 58,758

Feb-19 804,851 3.9 0.28 0.28 0.40 2.4 0.24 0.03 47,880

Mar-19 773,341 3.5 0.27 0.27 0.39 2.3 0.23 0.03 46,005

Apr-19 1,052,577 4.7 0.31 0.31 0.53 3.2 0.32 0.04 62,617

May-19 1,100,559 5.1 0.10 0.10 0.55 3.3 0.33 0.04 65,471

Jun-19 1,070,796 4.7 0.02 0.02 0.54 3.2 0.32 0.04 63,701

Jul-19 1,122,630 4.8 0.00 0.00 0.56 3.4 0.34 0.04 66,784

Aug-19 1,117,499 4.5 0.03 0.03 0.56 3.4 0.34 0.04 66,479

Sep-19 1,081,214 3.4 0.18 0.18 0.54 3.2 0.32 0.04 64,320

Oct-19 871,510 2.8 0.15 0.15 0.44 2.6 0.26 0.03 51,845

Nov-19 998,245 4.0 0.27 0.27 0.50 3.0 0.30 0.03 59,385

Dec-19 851,336 3.6 0.57 0.57 0.43 2.6 0.26 0.03 50,645

Maximum 1,192,710 5.9 2.80 1.90 0.60 3.6 0.36 0.04 70,953

Month1

Monthly Heat 

Input 

(MMBtu/mo)2

Monthly Emissions (tons/mo)

2. Per the facility's quarterly Part 75 emissions reports to EPA submitted through the Emissions Collection and Monitoring Plan System 

(ECMPS).

3. Per the facility's quarterly Title V monitoring reports to the Georgia EPD. If the monthly average CO emission rate, based on the reported CO 

emissions divided by the heat input for the month, exceeded the facility's permitted CO emission limit of 2.0 ppmvd @ 15% O2 (equivalent to 

0.00448 lb/MMBtu), the CO emissions for that month were re-calculated using the CO emission limit multiplied by the monthly heat input.

1. A five-year lookback period is allowed for determining baseline actual emissions for existing electric utility steam generating units, per 40 

CFR 52.21(b)(48)(i).

8B Trinity Consultants Page 3 of 9
Appendix B - New Source Review Calculations

Oglethorpe Power Corporation - Chattahoochee Energy Facility

Table B-12. Baseline Actual Emissions - Units 8A and 8B

NOX CO VOC PM10/PM2.5 SO2 H2SO4 CO2e NOX CO VOC PM10/PM2.5 SO2 H2SO4 CO2e NOX CO VOC PM10/PM2.5 SO2 H2SO4 CO2e

Jul-15 10.0 0.7 1.0 6.0 0.60 0.07 119,050

Aug-15 10.2 1.7 0.9 5.5 0.55 0.06 109,567

Sep-15 9.0 2.4 0.8 4.6 0.46 0.05 91,763

Oct-15 10.7 0.9 1.1 6.6 0.66 0.08 130,396

Nov-15 5.9 2.4 0.5 3.2 0.32 0.04 64,035

Dec-15 8.3 3.9 0.9 5.3 0.53 0.06 104,717

Jan-16 9.1 3.7 1.1 6.3 0.63 0.07 125,060

Feb-16 7.0 3.3 0.8 4.5 0.45 0.05 89,866

Mar-16 1.8 0.2 0.2 1.2 0.12 0.01 24,428

Apr-16 5.2 0.3 0.6 3.4 0.34 0.04 66,786

May-16 10.1 1.3 1.1 6.8 0.68 0.08 135,314

Jun-16 9.5 0.7 1.1 6.5 0.65 0.07 128,080 96.7 21.6 10.0 60.0 6.0 0.69 1,189,062

Jul-16 9.3 1.8 1.1 6.7 0.67 0.08 131,974 96.0 22.7 10.1 60.6 6.1 0.70 1,201,985

Aug-16 9.3 2.4 1.1 6.8 0.68 0.08 134,911 95.2 23.4 10.3 61.9 6.2 0.71 1,227,330

Sep-16 9.1 1.9 1.1 6.6 0.66 0.08 130,253 95.2 22.9 10.7 63.8 6.4 0.73 1,265,820

Oct-16 8.6 1.8 1.2 6.9 0.69 0.08 137,196 93.1 23.8 10.7 64.2 6.4 0.74 1,272,619

Nov-16 3.4 1.4 0.4 2.5 0.25 0.03 48,922 90.7 22.8 10.6 63.4 6.3 0.73 1,257,506

Dec-16 10.2 0.9 1.0 6.2 0.62 0.07 122,307 92.5 19.7 10.7 64.3 6.4 0.74 1,275,096

Jan-17 11.1 0.3 1.2 7.0 0.70 0.08 138,754 94.6 16.3 10.8 65.0 6.5 0.75 1,288,790

Feb-17 9.8 0.3 1.0 6.2 0.62 0.07 123,507 97.3 13.2 11.1 66.7 6.7 0.77 1,322,432

Mar-17 7.9 0.1 0.8 5.0 0.50 0.06 98,705 103.3 13.2 11.8 70.4 7.0 0.81 1,396,708

Apr-17 7.1 1.9 0.8 4.7 0.47 0.05 92,300 105.2 14.8 12.0 71.7 7.2 0.82 1,422,223

May-17 8.7 2.1 1.0 6.1 0.61 0.07 120,154 103.8 15.6 11.8 71.0 7.1 0.81 1,407,063

Jun-17 9.3 1.3 1.1 6.4 0.64 0.07 125,937 103.6 16.2 11.8 70.8 7.1 0.81 1,404,920 100.2 18.9 10.9 65.4 6.5 0.75 1,296,991

Jul-17 9.7 1.0 1.2 6.9 0.69 0.08 136,637 104.0 15.4 11.9 71.1 7.1 0.82 1,409,583 100.0 19.0 11.0 65.9 6.6 0.76 1,305,784

Aug-17 9.0 1.3 1.1 6.7 0.67 0.08 132,722 103.8 14.3 11.8 71.0 7.1 0.81 1,407,394 99.5 18.8 11.1 66.4 6.6 0.76 1,317,362

Sep-17 8.0 0.9 1.1 6.6 0.66 0.08 130,855 102.7 13.3 11.9 71.0 7.1 0.82 1,407,996 98.9 18.1 11.3 67.4 6.7 0.77 1,336,908

Oct-17 8.6 1.2 1.1 6.6 0.66 0.08 130,393 102.7 12.7 11.8 70.7 7.1 0.81 1,401,194 97.9 18.2 11.3 67.4 6.7 0.77 1,336,907

Nov-17 6.0 1.0 0.7 4.1 0.41 0.05 81,202 105.2 12.3 12.1 72.3 7.2 0.83 1,433,473 98.0 17.5 11.3 67.9 6.8 0.78 1,345,490

Dec-17 7.9 0.8 0.9 5.7 0.57 0.07 112,435 102.9 12.2 12.0 71.8 7.2 0.82 1,423,601 97.7 15.9 11.4 68.0 6.8 0.78 1,349,349

Jan-18 8.0 1.9 1.0 5.8 0.58 0.07 115,015 99.9 13.8 11.8 70.6 7.1 0.81 1,399,863 97.2 15.0 11.3 67.8 6.8 0.78 1,344,326

Feb-18 7.1 1.6 0.8 4.7 0.47 0.05 94,086 97.2 15.1 11.5 69.1 6.9 0.79 1,370,441 97.2 14.2 11.3 67.9 6.8 0.78 1,346,436

Mar-18 3.8 1.2 0.4 2.3 0.23 0.03 45,137 93.2 16.1 11.1 66.4 6.6 0.76 1,316,873 98.3 14.7 11.4 68.4 6.8 0.79 1,356,791

Apr-18 9.1 1.3 1.0 6.0 0.60 0.07 118,729 95.2 15.6 11.3 67.7 6.8 0.78 1,343,301 100.2 15.2 11.6 69.7 7.0 0.80 1,382,762

May-18 9.2 1.1 1.1 6.3 0.63 0.07 124,905 95.7 14.6 11.3 68.0 6.8 0.78 1,348,053 99.8 15.1 11.6 69.5 6.9 0.80 1,377,558

Jun-18 7.0 0.9 0.9 5.3 0.53 0.06 105,590 93.4 14.1 11.2 67.0 6.7 0.77 1,327,706 98.5 15.2 11.5 68.9 6.9 0.79 1,366,313

Jul-18 7.9 0.3 1.1 6.8 0.68 0.08 134,710 91.6 13.4 11.2 66.9 6.7 0.77 1,325,779 97.8 14.4 11.5 69.0 6.9 0.79 1,367,681

Aug-18 7.7 1.2 1.1 6.3 0.63 0.07 125,572 90.3 13.2 11.1 66.5 6.6 0.76 1,318,629 97.0 13.8 11.5 68.7 6.9 0.79 1,363,011

Sep-18 4.9 0.6 0.8 4.7 0.47 0.05 93,159 87.2 13.0 10.8 64.6 6.5 0.74 1,280,933 94.9 13.1 11.3 67.8 6.8 0.78 1,344,465

Oct-18 0.5 0.1 0.1 0.6 0.06 0.01 11,234 79.1 11.8 9.8 58.6 5.9 0.67 1,161,773 90.9 12.2 10.8 64.6 6.5 0.74 1,281,484

Nov-18 4.5 1.8 0.4 2.7 0.27 0.03 53,004 77.7 12.6 9.5 57.2 5.7 0.66 1,133,575 91.4 12.4 10.8 64.7 6.5 0.74 1,283,524

Dec-18 7.9 1.6 0.9 5.7 0.57 0.07 112,540 77.7 13.4 9.5 57.2 5.7 0.66 1,133,680 90.3 12.8 10.8 64.5 6.4 0.74 1,278,641

Jan-19 7.9 1.2 1.0 6.2 0.62 0.07 122,746 77.6 12.7 9.6 57.6 5.8 0.66 1,141,411 88.7 13.2 10.7 64.1 6.4 0.74 1,270,637

Feb-19 8.0 0.9 0.9 5.2 0.52 0.06 102,635 78.4 12.0 9.7 58.0 5.8 0.67 1,149,960 87.8 13.5 10.6 63.6 6.4 0.73 1,260,201

Mar-19 7.0 0.9 0.7 4.4 0.44 0.05 88,145 81.6 11.6 10.0 60.2 6.0 0.69 1,192,968 87.4 13.9 10.6 63.3 6.3 0.73 1,254,921

Apr-19 9.7 1.2 1.0 6.3 0.63 0.07 124,100 82.2 11.5 10.1 60.4 6.0 0.69 1,198,340 88.7 13.5 10.7 64.1 6.4 0.74 1,270,821

May-19 10.2 0.5 1.1 6.5 0.65 0.07 127,903 83.2 10.8 10.1 60.6 6.1 0.70 1,201,337 89.5 12.7 10.7 64.3 6.4 0.74 1,274,695

Jun-19 9.5 0.4 1.0 6.2 0.62 0.07 123,542 85.7 10.3 10.3 61.5 6.1 0.71 1,219,289 89.6 12.2 10.7 64.2 6.4 0.74 1,273,497

Jul-19 9.9 0.1 1.1 6.7 0.67 0.08 133,505 87.8 10.2 10.3 61.4 6.1 0.71 1,218,084 89.7 11.8 10.7 64.1 6.4 0.74 1,271,931

Aug-19 9.6 0.3 1.1 6.7 0.67 0.08 133,460 89.7 9.3 10.3 61.8 6.2 0.71 1,225,972 90.0 11.3 10.7 64.2 6.4 0.74 1,272,301

Sep-19 8.2 1.1 1.1 6.3 0.63 0.07 124,761 93.0 9.8 10.6 63.4 6.3 0.73 1,257,574 90.1 11.4 10.7 64.0 6.4 0.73 1,269,253

Oct-19 6.6 0.7 0.8 4.9 0.49 0.06 97,057 99.1 10.4 11.3 67.7 6.8 0.78 1,343,398 89.1 11.1 10.5 63.2 6.3 0.73 1,252,585

Nov-19 8.3 1.0 0.9 5.7 0.57 0.07 112,633 102.8 9.7 11.8 70.8 7.1 0.81 1,403,027 90.2 11.1 10.7 64.0 6.4 0.73 1,268,301

Dec-19 7.7 1.3 0.8 5.0 0.50 0.06 99,204 102.6 9.4 11.7 70.1 7.0 0.80 1,389,691 90.1 11.4 10.6 63.6 6.4 0.73 1,261,685

Maximum 11.1 3.9 1.2 7.0 0.70 0.08 138,754 105.2 23.8 12.1 72.3 7.2 0.83 1,433,473 100.2 19.0 11.6 69.7 7.0 0.80 1,382,762

Baseline Period Start Date May-16 Aug-15 May-16 May-16 May-16 May-16 May-16

Baseline Period End Date Apr-18 Jul-17 Apr-18 Apr-18 Apr-18 Apr-18 Apr-18

Month

Total Monthly Emissions (tons/mo) 12-Month Rolling Total Emissions (tpy) 24-Month Rolling Annual Average Emissions (tpy)

BAE Trinity Consultants Page 4 of 9
Appendix B - New Source Review Calculations

Oglethorpe Power Corporation - Chattahoochee Energy Facility

Table B-13. "Could Have Accommodated" Emissions (except CO) - Units 8A and 8B

NOX VOC PM10/PM2.5 SO2 H2SO4 CO2e NOX VOC PM10/PM2.5 SO2 H2SO4 CO2e NOX VOC PM10/PM2.5 SO2 H2SO4 CO2e

May-16 10.1 1.1 6.8 0.68 0.08 135,314 10.1 1.1 6.8 0.68 0.08 135,314

Jun-16 9.5 1.1 6.5 0.65 0.07 128,080 9.5 1.1 6.8 0.68 0.08 134,911

Jul-16 9.3 1.1 6.7 0.67 0.08 131,974 9.5 1.1 6.8 0.68 0.08 134,911

Aug-16 9.3 1.1 6.8 0.68 0.08 134,911 9.5 1.1 6.8 0.68 0.08 134,911

Sep-16 9.1 1.1 6.6 0.66 0.08 130,253 9.1 1.2 6.9 0.69 0.08 137,196

Oct-16 8.6 1.2 6.9 0.69 0.08 137,196 9.1 1.2 6.9 0.69 0.08 137,196

Nov-16 3.4 0.4 2.5 0.25 0.03 48,922 9.1 1.2 6.9 0.69 0.08 137,196

Dec-16 10.2 1.0 6.2 0.62 0.07 122,307 11.1 1.2 7.0 0.70 0.08 138,754

Jan-17 11.1 1.2 7.0 0.70 0.08 138,754 11.1 1.2 7.0 0.70 0.08 138,754

Feb-17 9.8 1.0 6.2 0.62 0.07 123,507 11.1 1.2 7.0 0.70 0.08 138,754

Mar-17 7.9 0.8 5.0 0.50 0.06 98,705 8.7 1.0 6.1 0.61 0.07 120,154

Apr-17 7.1 0.8 4.7 0.47 0.05 92,300 8.7 1.0 6.1 0.61 0.07 120,154 116.4 13.5 81.1 8.1 0.93 1,608,206

May-17 8.7 1.0 6.1 0.61 0.07 120,154 8.7 1.0 6.1 0.61 0.07 120,154 115.0 13.4 80.3 8.0 0.92 1,593,046

Jun-17 9.3 1.1 6.4 0.64 0.07 125,937 9.7 1.2 6.9 0.69 0.08 136,637 115.1 13.4 80.4 8.0 0.92 1,594,771

Jul-17 9.7 1.2 6.9 0.69 0.08 136,637 9.7 1.2 6.9 0.69 0.08 136,637 115.3 13.4 80.5 8.1 0.92 1,596,496

Aug-17 9.0 1.1 6.7 0.67 0.08 132,722 9.7 1.2 6.9 0.69 0.08 136,637 115.4 13.5 80.6 8.1 0.93 1,598,222

Sep-17 8.0 1.1 6.6 0.66 0.08 130,855 8.6 1.1 6.6 0.66 0.08 130,855 114.9 13.4 80.3 8.0 0.92 1,591,881

Oct-17 8.6 1.1 6.6 0.66 0.08 130,393 8.6 1.1 6.6 0.66 0.08 130,855 114.4 13.3 80.0 8.0 0.92 1,585,541

Nov-17 6.0 0.7 4.1 0.41 0.05 81,202 8.6 1.1 6.6 0.66 0.08 130,855 113.9 13.3 79.6 8.0 0.91 1,579,200

Dec-17 7.9 0.9 5.7 0.57 0.07 112,435 8.0 1.0 5.8 0.58 0.07 115,015 110.9 13.1 78.4 7.8 0.90 1,555,461

Jan-18 8.0 1.0 5.8 0.58 0.07 115,015 8.0 1.0 5.8 0.58 0.07 115,015 107.9 12.9 77.2 7.7 0.89 1,531,722

Feb-18 7.1 0.8 4.7 0.47 0.05 94,086 8.0 1.0 5.8 0.58 0.07 115,015 104.8 12.7 76.0 7.6 0.87 1,507,983

Mar-18 3.8 0.4 2.3 0.23 0.03 45,137 9.1 1.0 6.0 0.60 0.07 118,729 105.3 12.7 76.0 7.6 0.87 1,506,558

Apr-18 9.1 1.0 6.0 0.60 0.07 118,729 9.1 1.0 6.0 0.60 0.07 118,729 105.7 12.7 75.9 7.6 0.87 1,505,133

"Could Have Accommodated" Emissions (tpy):3

116.4 13.5 81.1 8.1 0.93 1,608,206

Spring: March - May

Summer: June - August

Fall: September - November

Winter: December - February

2. Calculated as the 12 consecutive month totals of the seasonally-adjusted monthly emissions during the baseline period.

3. The "Could Have Accommodated" emissions for each pollutant are based on the maximum of the seasonally-adjusted 12-month totals during the baseline period.

1. The seasonally-adjusted monthly emissions are based on the highest monthly emissions during the three consecutive months in a season applied to all the consecutive months in the season. The seasons in Georgia are as follows:

Seasonally-Adjusted Monthly Emissions (tons/mo)1Seasonally-Adjusted 12-Month Total Emissions (tpy)

2

Actual Monthly Emissions (tons/mo) Month

CHA Trinity Consultants Page 5 of 9
Appendix B - New Source Review Calculations

Oglethorpe Power Corporation - Chattahoochee Energy Facility

Table B-14. "Could Have Accommodated" CO Emissions - Units 8A and 8B

Month

Aug-15 1.7 1.7

Sep-15 2.4 2.4

Oct-15 0.9 2.4

Nov-15 2.4 2.4

Dec-15 3.9 3.9

Jan-16 3.7 3.9

Feb-16 3.3 3.9

Mar-16 0.2 1.3

Apr-16 0.3 1.3

May-16 1.3 1.3

Jun-16 0.7 2.4

Jul-16 1.8 2.4 29.4

Aug-16 2.4 2.4 30.0

Sep-16 1.9 1.9 29.5

Oct-16 1.8 1.9 29.0

Nov-16 1.4 1.9 28.5

Dec-16 0.9 0.9 25.4

Jan-17 0.3 0.9 22.3

Feb-17 0.3 0.9 19.2

Mar-17 0.1 2.1 20.1

Apr-17 1.9 2.1 20.9

May-17 2.1 2.1 21.7

Jun-17 1.3 1.3 20.6

Jul-17 1.0 1.3 19.6

"Could Have Accommodated" CO Emissions (tpy):3

30.0

Spring: March - May

Summer: June - August

Fall: September - November

Winter: December - February

2. Calculated as the 12 consecutive month totals of the seasonally-adjusted monthly emissions during the baseline period.

3. The "Could Have Accommodated" emissions for each pollutant are based on the maximum of the seasonally-adjusted 12-month totals during the baseline period.

1. The seasonally-adjusted monthly emissions are based on the highest monthly emissions during the three consecutive months in a season applied to all the consecutive months in the season. The seasons in Georgia are as follows:

Actual Monthly CO 

Emissions 

(tons/mo)

Seasonally-Adjusted 

Monthly CO Emissions 

(tons/mo)1

Seasonally-Adjusted 

12-Month Total CO 

Emissions (tpy)2

CHA Trinity Consultants Page 6 of 9
Appendix B - New Source Review Calculations

Oglethorpe Power Corporation - Chattahoochee Energy Facility

Table B-15. Projected Actual Emissions - Units 8A and 8B

30.2

Pollutant Emission Factor

(lb/MMBtu)

Projected Actual 

Emissions

(tpy)

NOX

1

1.01E-02 153.1

CO1

4.48E-03 67.6

VOC 1.00E-03 15.1

PM10/PM2.5 6.00E-03 90.6

SO2 6.00E-04 9.1

H2SO4 6.89E-05 1.0

CO2e 118.98 1,796,567

Estimated Future Max. Annual Heat Input 

(million MMBtu/yr)

1. The projected actual NOX and CO emission rates were conservatively based on 

the maximum of the monthly average emission rates (monthly emissions divided by 

monthly heat input) during the 24-month baseline period for each pollutant.

PAE Trinity Consultants Page 7 of 9
Appendix B - New Source Review Calculations

Oglethorpe Power Corporation - Chattahoochee Energy Facility

Table B-16. Cooling Tower Associated Emissions Increase

Emission 

Source

Total 

Dissolved 

Solids1

(mg/L)

Drift Loss 

Increase2

(gpm)

PM 

Emissions 

Increase3

(tpy)

PM10 

Emissions 

Increase4

(tpy)

PM2.5 

Emissions 

Increase4

(tpy)

Cooling Tower 602 0.23 0.31 0.27 1.5E-03

1. Average cooling tower water TDS content, per facility documentation.

2. Based on cooling tower modeling performed by Siemens at 59 °F ambient with duct burners firing.

Table B-17. Derivation of PM10/PM2.5 Fraction for Cooling Tower Emissions1

Drift Droplet 

Diameter [Dd]

(μm)

Drift 

Droplet 

Volume 

[Vdroplet]

2

(μm3)

Drift 

Droplet 

Mass 

[Mdroplet]

3

(μg)

Droplet 

Particle Mass 

[MTDS]

4

(μg)

Solid 

Particle 

Diameter 

[DTDS]

5

(μm)

EPRI 

Cumulative 

% Mass 

Smaller6

(%)

Interpolation 

Value for 

PM10

7

(%)

Interpolation 

Value for 

PM2.5

7

(%)

0 0.00E+00 0.00E+00 0.00E+00 0.000 0 -- --

10 5.24E+02 5.24E-04 3.15E-07 0.649 0 -- --

20 4.19E+03 4.19E-03 2.52E-06 1.298 0.196 -- --

30 1.41E+04 1.41E-02 8.51E-06 1.948 0.226 -- --

40 3.35E+04 3.35E-02 2.02E-05 2.597 0.514 -- 0.471

50 6.54E+04 6.54E-02 3.94E-05 3.246 1.816 -- --

60 1.13E+05 1.13E-01 6.81E-05 3.895 5.702 -- --

70 1.80E+05 1.80E-01 1.08E-04 4.545 21.348 -- --

90 3.82E+05 3.82E-01 2.30E-04 5.843 49.812 -- --

110 6.97E+05 6.97E-01 4.20E-04 7.141 70.509 -- --

130 1.15E+06 1.15E+00 6.93E-04 8.440 82.023 -- --

150 1.77E+06 1.77E+00 1.06E-03 9.738 88.012 -- --

180 3.05E+06 3.05E+00 1.84E-03 11.686 91.032 88.418 --

210 4.85E+06 4.85E+00 2.92E-03 13.634 92.468 -- --

240 7.24E+06 7.24E+00 4.36E-03 15.581 94.091 -- --

300 1.41E+07 1.41E+01 8.51E-03 19.477 96.288 -- --

350 2.24E+07 2.24E+01 1.35E-02 22.723 97.011 -- --

400 3.35E+07 3.35E+01 2.02E-02 25.969 98.34 -- --

450 4.77E+07 4.77E+01 2.87E-02 29.215 99.071 -- --

600 1.13E+08 1.13E+02 6.81E-02 38.953 100 -- --

2. Vdroplet = 4/3 π (Dd /2)3 [Equation 2 of the Document]

3. Mdroplet = density (ρw) of water * Vdroplet = ρw * 4/3 π (Dd /2)3 

ρw = 1.00E-06 μg/μm3

4. MTDS = TDS * Mdroplet [Equation 3 of the Document, with TDS in units of ppm]

TDS = 602 mg/L Total Dissolved Solids content for CEF's cooling tower

TDS = 602 ppm

5. MTDS = (ρTDS) (VTDS) = (ρTDS) (4/3)π (DTDS /2)3 [Equation 5 of the Document]

Therefore, the equation can be solved for DTDS: DTDS = {MTDS/[(ρTDS)* 4/3 * π]}1/3 × 2

2.20E-06 μg/μm3

%MassPM10 = %Mass Less than 10 DTDS + [(10 - DTDS Less Than 10) / (DTDS Greater Than 10 - DTDS Less Than 10)] * (%Mass Greater than 

10 DTDS - %Mass Less than 10 DTDS)

i.e., 82.041% = 82.023% + [ (10 - 9.995) / (11.533 - 9.995) ] * (88.012% - 82.023%)

Assume solid particulates have the same density (ρTDS) as sodium 

chloride per the Document:

1. Based on the methodology discussed in Calculating Realistic PM 10 Emissions from Cooling Towers by Joel Reisman and Gordon Frisbie, 

2002 (the Document). 

https://ww2.energy.ca.gov/sitingcases/palomar/documents/applicants_files/Data_Request_Response/Air%20Quality/Attachment%204-1.pdf

6. Based on drift eliminator test data from a test conducted by Environmental Systems Corporation (ESC) at the Electric Power Research 

Institute (EPRI) test facility in Houston, Texas in 1988 (Aull, 1999) as documented in Table 1 of the Document. 

7. DTDS represents the particle size of collected material in droplet. The EPRI cumulative % mass smaller indicates the percentage of material 

in that specific water droplet size that has a diameter smaller than DTDS. Therefore, linear interpolation between calculated DTDS is necessary 

to ascertain the specific mass percentages to estimate PM10 and PM2.5 emissions. For example, at 1,000 mg/L TDS: 

4. PM10 and PM2.5 emissions are estimated based on the particulate size distribution below, interpolated from data in Calculating 

Realistic PM 10 Emissions from Cooling Towers by Joel Reisman and Gordon Frisbie, 2002. Detailed derivation of PM10/PM2.5 fractions 

is shown in the table below. 

3. Annual PM Emission Rate (ton/yr) = Drift Loss Increase (gal/min) × TDS (mg/L) × 3.78541 (L/gal) × 2.2045E-06 (lb/mg) × 60 

(min/hr) × 8,760 (hr/yr) / 2,000 (lb/ton)

Cooling Tower Trinity Consultants Page 8 of 9
Appendix B - New Source Review Calculations

Oglethorpe Power Corporation - Chattahoochee Energy Facility

Table B-18. Project Emissions Increase

Baseline 

Actual 

Emissions

(tpy)

"Could Have 

Accommodated" 

Emissions

(tpy)

Projected 

Actual 

Emissions

(tpy)

Project 

Emissions 

Increase1

(tpy)

NOX 100.2 116.4 153.1 36.7 - 36.7 40 No

CO 19.0 30.0 67.6 37.6 - 37.6 100 No

VOC 11.6 13.5 15.1 1.59 - 1.6 40 No

PM 69.7 81.1 90.6 9.5 0.31 9.8 25 No

PM10 69.7 81.1 90.6 9.5 0.27 9.8 15 No

PM2.5 69.7 81.1 90.6 9.5 1.5E-03 9.5 10 No

SO2 7.0 8.1 9.1 0.95 - 0.9 40 No

H2SO4 0.80 0.93 1.0 0.11 - 0.1 7 No

CO2e

3

1,382,762 1,608,206 1,796,567 188,361 - 188,361 75,000 No

2. 40 CFR 52.21(b)23(i) and Georgia Air Quality Control Rule 391-3-1-.03(8)(c)15

1. Project Emissions Increase = (Projected Actual Emissions - Baseline Actual Emissions) - ("Could Have Accommodated" Emissions - Baseline Actual Emissions)

3. NSR permitting for CO2e is only required if the project emissions increase exceeds the NSR SER of 75,000 tpy and if NSR permitting is triggered for at least one other 

regulated pollutant.

Pollutant

Units 8A and 8B Cooling 

Tower 

Associated 

Emissions 

Increase

(tpy)

NSR 

Significant 

Emission 

Rate2

(tpy)

NSR 

Triggered?

Total 

Project 

Emissions 

Increase

(tpy)

PEI Trinity Consultants Page 9 of 9
Oglethorpe Power Corporation | Title V Significant Modification with Construction

Trinity Consultants C-1

APPENDIX C. TOXICS IMPACT ANALYSIS DOCUMENTATION
Appendix C - Toxics Impact Analysis

Oglethorpe Power Corporation - Chattahoochee Energy Facility

Table C-1. Natural Gas Burning Equipment - Operating Parameters

Estimated Maximum 

Annual Operating 

Capacity1

Estimated Maximum Short 

Term Operating Capacity

Emission Source Source No. Fuel Type (Million MMBtu/yr) (MMBtu/hr)

CT8A Combustion Turbine CT8A Natural Gas 15.69 1,900.0

CT8B Combustion Turbine CT8B Natural Gas 15.69 1,900.0

DB8A Duct Burner DB8A Natural Gas 0.83 95.0

DB8B Duct Burner DB8B Natural Gas 0.83 95.0

Table C-2. Potential TAP Emissions from Combustion Turbines

Potential Emissions2 Potential Emissions3

Combustion Turbines Combustion Turbines

Pollutant (lb/MMBtu) (tpy) (lb/hr)

Lead -- -- --

1,3-Butadiene 4.30E-07 6.75E-03 1.63E-03

Acetaldehyde 4.00E-05 0.63 1.52E-01

Acrolein 6.40E-06 1.00E-01 2.43E-02

Ammonia4 1.84E+02 4.20E+01

Benzene 1.20E-05 1.88E-01 4.56E-02

Ethylbenzene 3.20E-05 0.50 1.22E-01

Formaldehyde5 1.14E-04 1.79 0.43

Naphthalene 1.30E-06 2.04E-02 4.94E-03

Propylene Oxide 2.90E-05 0.45 1.10E-01

Sulfuric Acid6 6.89E-05 1.08 2.62E-01

Toluene 1.30E-04 2.04 4.94E-01

Xylenes 6.40E-05 1.00 2.43E-01

4. Based on ammonia slip of 10 ppmvd from the SCR system, as derived during the initial permitting for the facility

5. Formaldehyde emission factor based on AP-42 Section 3.1 Database (April 2000) for Frame Type CTs greater than 40 MW.

Table C-3. Potential TAP Emissions from Duct Burners

Potential Emissions2 Potential Emissions3

Duct Burners Duct Burners

Pollutant (lb/MMscf) (tpy) (lb/hr)

Benzene 2.10E-03 1.71E-03 3.91E-04

1,4-Dichlorobenzene 1.20E-03 9.79E-04 2.24E-04

Formaldehyde 7.50E-02 6.12E-02 1.40E-02

Hexane 1.80E+00 1.47 3.35E-01

Naphthalene 6.10E-04 4.98E-04 1.14E-04

Pentane 2.60E+00 2.12 4.84E-01

Propane 1.60E+00 1.31 2.98E-01

Sulfuric Acid4 7.03E-02 5.73E-02 1.31E-02

Toluene 3.40E-03 2.77E-03 6.33E-04

Arsenic 2.00E-04 1.63E-04 3.73E-05

Barium 4.40E-03 3.59E-03 8.20E-04

Beryllium 1.20E-05 9.79E-06 2.24E-06

Cadmium 1.10E-03 8.97E-04 2.05E-04

Chromium 1.40E-03 1.14E-03 2.61E-04

Cobalt 8.40E-05 6.85E-05 1.56E-05

Copper 8.50E-04 6.94E-04 1.58E-04

Manganese 3.80E-04 3.10E-04 7.08E-05

Mercury 2.60E-04 2.12E-04 4.84E-05

Molybdenum 1.10E-03 8.97E-04 2.05E-04

Nickel 2.10E-03 1.71E-03 3.91E-04

Selenium 2.40E-05 1.96E-05 4.47E-06

1. Emission factors per AP-42, Section 1.4 Natural Gas Combustion, Tables 1.4-3 and 1.4-4.

1. Based on post project heat input capacity per turbine at 59F (1,790.7 MMBtu/hr) and the permitted heat input capacity for the duct burners (95 MMBtu/hr) times 

potential operation of 8,760 hrs/yr.

3. Potential Emissions (lb/hr) = Emission Factor (lb/MMBtu) * Maximum Short Term Operating Capacity (MMBtu/hr)

Emission Factor1

Emission Factor1

6. Sulfuric Acid emission factor based on a 7.5% conversion of SO2 to H2SO4, consistent with the facility's initial November 2000 PSD 

permit application.

1. Emission factors per AP-42, Section 3.1 Stationary Gas Turbine, Tables 3.1.-2a and 3.1-3 unless otherwise noted.

4. Sulfuric Acid emission factor based on a 7.5% conversion of SO2 to H2SO4, consistent with the facility's initial November 2000 PSD permit application.

2. Potential Emissions (tpy) = Emission Factor (lb/MMBtu) * Maximum Annual Operating Capacity (Million MMBtu/yr) * 1E6 MMBtu/ 

Million MMBtu / 2,000 lb/ton

3. Potential Emissions (lb/hr) = Emission Factor (lb/MMBtu) * Maximum Short Term Operating Capacity (MMBtu/hr)

2. Potential Emissions (tpy) = Emission Factor (lb/MMscf) / 1,020 (MMBtu/MMscf) * Maximum Annual Operating Capacity (Million MMBtu/yr) * 1E6 MMBtu/ Million MMBtu / 

2,000 lb/ton 

TAP Trinity Consultants Page 1 of 3
Appendix C - Toxics Impact Analysis

Oglethorpe Power Corporation - Chattahoochee Energy Facility

Table C-4. Toxic Air Pollutant Emissions Compared to Minimum Emission Rates

OPC Chattahoochee 

Annual

Emissions

OPC Chattahoochee 

Annual

Emissions1

Short Term Emission 

Rate2

Minimum Emission Rate

(MER)3

(tpy) (lb/yr) (g/s) (lb/yr) Above MER?

Arsenic 1.63E-04 0.33 4.69E-06 0.057 Yes

Ammonia 184 367,920 5.29E+00 24,333 Yes

Beryllium 9.79E-06 0.02 2.82E-07 0.97 No

Cadmium 8.97E-04 1.8 2.58E-05 1.35 Yes

Acrolein 1.00E-01 201 3.06E-03 4.87 Yes

Lead -- -- -- 5.84 No

1,3-Butadiene 6.75E-03 13.5 2.06E-04 7.30 Yes

Cobalt 6.85E-05 0.14 1.97E-06 11.7 No

Manganese 3.10E-04 0.62 8.92E-06 12.2 No

Selenium 1.96E-05 0.04 5.63E-07 23.4 No

Chromium 1.14E-03 2.3 3.29E-05 24.33 No

Benzene 1.90E-01 380 5.79E-03 31.6 Yes

Nickel 1.71E-03 3.4 4.93E-05 38.6 No

Barium 3.59E-03 7.2 1.03E-04 57.9 No

Mercury 2.12E-04 0.42 6.10E-06 73.0 No

Copper 6.94E-04 1.4 1.99E-05 117 No

Sulfuric Acid 1.14 2,276 3.46E-02 117 Yes

Formaldehyde 1.85 3,699 5.63E-02 267 Yes

Propylene Oxide 4.55E-01 910 1.39E-02 657 Yes

Naphthalene 2.09E-02 41.8 6.37E-04 730 No

Acetaldehyde 0.63 1,255 1.92E-02 1,107 Yes

Molybdenum 8.97E-04 1.8 2.58E-05 1,738 No

Xylenes 1.00 2,008 3.06E-02 24,333 No

Hexane 1.47 2,937 4.22E-02 170,331 No

1,4-Dichlorobenzene 9.79E-04 2.0 2.82E-05 194,664 No

Propane 1.3 2,611 3.76E-02 208,600 No

Ethylbenzene 0.50 1,004 1.53E-02 243,330 No

Pentane 2.1 4,243 6.10E-02 341,858 No

Toluene 2.04 4,084 6.23E-02 1,216,650 No

3. From EPD's Guideline for Ambient Impact Assessment of Toxic Air Pollutant Emissions, updated October 2018.

Table C-5. Worst Case Stack Parameters for SCREEN31

Source Type

Height

(m)

Diameter

(m)

Velocity

(m/s)

Gas Temperature

(K)

Point 39.624 5.03 24.81 366.2

1. Conservatively assumes all emissions are from a single stack.

Table C-6. SCREEN3 Modeling Results at 1 g/s

Maximum 1-Hour Impact 1.007 μg/m3

Maximum 15-Minute Impact1 1.329 μg/m3

Maximum 24-Hour Impact2 0.532 μg/m3

Maximum Annual Impact3 0.043 μg/m3

1. Annual Emissions (lb/yr) = Annual Emissions (ton/yr) * 2,000 lb/ton.

2. Short Term Emission Rate (g/s) = Short Term Emissions (lb/hr) * 453.592 (g/lb) / 3,600 (s/hr)

Toxic Air Pollutant (TAP)

1. The 15-minute impact equals the 1-hour impact times 1.32 per the 

EPD Guideline .

2. The 24-hour impact equals the 1-hour impact times 0.4 per the

EPD Guideline .

3. The annual impact equals the 1-hour impact times 0.08 per the

EPD Guideline .

TAP Trinity Consultants Page 2 of 3
Appendix C - Toxics Impact Analysis

Oglethorpe Power Corporation - Chattahoochee Energy Facility

Table C-7. Modeling Results Compared to AAC Values1

Maximum

Annual Impact Annual AAC

Maximum

24-Hour Impact 24-Hour AAC

Maximum

15-Minute Impact 1

μg/m3 μg/m3 % of AAC μg/m3 μg/m3 % of ACC μg/m3 

Arsenic 2.00E-07 2.33E-04 < 1.00% N/A N/A -- 6.24E-06 Ammonia 2.25E-01 1.00E+02 < 1.00% N/A N/A -- 7.03E+00 Cadmium 1.10E-06 5.56E-03 < 1.00% N/A N/A -- 3.43E-05 Acrolein 1.30E-04 2.00E-02 < 1.00% N/A N/A -- 4.07E-03 1,3-Butadiene 8.76E-06 3.00E-02 < 1.00% N/A N/A -- 2.74E-04 Benzene 2.46E-04 1.30E-01 < 1.00% N/A N/A -- 7.70E-03 Sulfuric Acid N/A N/A -- 1.84E-02 2.40E+00 < 1.00% 4.60E-02 Formaldehyde 2.40E-03 1.10E+00 < 1.00% N/A N/A -- 7.49E-02 Propylene Oxide 5.91E-04 2.70E+00 < 1.00% N/A N/A -- N/A Acetaldehyde 8.15E-04 4.55E+00 < 1.00% N/A N/A -- 2.55E-02 

1. AAC values from the EPD Guideline, updated October 2018.

Toxic Air Pollutant (TAP)

TAP Results Trinity Consultants 
                                                                      06/11/20

08:43:04

  ***  SCREEN3 MODEL RUN  ***

  *** VERSION DATED 13043 ***

OPC CEF                                                                        

SIMPLE TERRAIN INPUTS:

    SOURCE TYPE            =        POINT

    EMISSION RATE (G/S)    =     1.000000    

    STACK HEIGHT (M)       =      39.6240

    STK INSIDE DIAM (M)    =       5.0300

    STK EXIT VELOCITY (M/S)=      24.8100

    STK GAS EXIT TEMP (K)  =     366.2000

    AMBIENT AIR TEMP (K)   =     293.0000

    RECEPTOR HEIGHT (M)    =       0.0000

    URBAN/RURAL OPTION     =        RURAL

    BUILDING HEIGHT (M)    =       0.0000

    MIN HORIZ BLDG DIM (M) =       0.0000

    MAX HORIZ BLDG DIM (M) =       0.0000

THE REGULATORY (DEFAULT) MIXING HEIGHT OPTION WAS SELECTED.

THE REGULATORY (DEFAULT) ANEMOMETER HEIGHT OF 10.0 METERS WAS ENTERED.

BUOY. FLUX =  307.606 M**4/S**3;  MOM. FLUX = 3115.149 M**4/S**2.

*** FULL METEOROLOGY ***

**********************************

*** SCREEN AUTOMATED DISTANCES ***

**********************************

*** TERRAIN HEIGHT OF    0. M ABOVE STACK BASE USED FOR FOLLOWING DISTANCES ***

   DIST     CONC             U10M   USTK  MIX HT   PLUME   SIGMA   SIGMA

    (M)   (UG/M**3)   STAB  (M/S)  (M/S)    (M)   HT (M)   Y (M)   Z (M)  DWASH

 ‐‐‐‐‐‐‐  ‐‐‐‐‐‐‐‐‐‐  ‐‐‐‐  ‐‐‐‐‐  ‐‐‐‐‐  ‐‐‐‐‐‐  ‐‐‐‐‐‐  ‐‐‐‐‐‐  ‐‐‐‐‐‐  ‐‐‐‐‐

     20.    0.000        1     1.0    1.1  1134.0 1132.98   29.99   29.48    NO

    100.   0.2489E‐03    5     1.0    1.6 10000.0  210.49   41.52   41.21    NO

    200.   0.8490E‐02    5     1.0    1.6 10000.0  210.49   50.18   49.22    NO

    300.   0.9384E‐02    5     1.0    1.6 10000.0  210.49   51.66   49.59    NO

    400.   0.1042E‐01    5     1.0    1.6 10000.0  210.49   53.55   50.00    NO

    500.   0.2185E‐01    1     3.0    3.3   960.0  404.08  127.44  120.06    NO

    600.   0.2120        1     3.0    3.3   960.0  404.08  148.57  167.67    NO

    700.   0.5080        1     3.0    3.3   960.0  404.08  169.18  225.68    NO

    800.   0.6735        1     3.0    3.3   960.0  404.08  189.36  294.23    NO

    900.   0.8346        1     2.0    2.2   640.0  586.30  230.72  385.91    NO

   1000.   0.9825        1     2.0    2.2   640.0  586.30  251.38  474.99    NO

   1100.    1.004        1     2.0    2.2   640.0  586.30  271.70  575.02    NO
   1200.   0.9674        1     2.0    2.2   640.0  586.30  290.61  685.62    NO

   1300.   0.9286        1     1.5    1.7   769.5  768.53  335.42  817.80    NO

   1400.   0.8971        1     1.5    1.7   769.5  768.53  349.46  948.29    NO

   1500.   0.8629        1     1.5    1.7   769.5  768.53  363.68 1090.67    NO

   1600.   0.8302        1     1.5    1.7   769.5  768.53  378.05 1244.85    NO

   1700.   0.7996        1     1.5    1.7   769.5  768.53  392.54 1410.80    NO

   1800.   0.7709        1     1.5    1.7   769.5  768.53  407.13 1588.50    NO

   1900.   0.7441        1     1.5    1.7   769.5  768.53  421.78 1777.96    NO

   2000.   0.7190        1     1.5    1.7   769.5  768.53  436.50 1979.20    NO

   2100.   0.6955        1     1.5    1.7   769.5  768.53  451.26 2192.25    NO

   2200.   0.6734        1     1.5    1.7   769.5  768.53  466.06 2417.14    NO

   2300.   0.6527        1     1.5    1.7   769.5  768.53  480.88 2653.91    NO

   2400.   0.6331        1     1.5    1.7   769.5  768.53  495.71 2902.61    NO

   2500.   0.6147        1     1.5    1.7   769.5  768.53  510.56 3163.26    NO

   2600.   0.5974        1     1.5    1.7   769.5  768.53  525.40 3435.93    NO

   2700.   0.5810        1     1.5    1.7   769.5  768.53  540.24 3720.65    NO

   2800.   0.5654        1     1.5    1.7   769.5  768.53  555.08 4017.46    NO

   2900.   0.5507        1     1.5    1.7   769.5  768.53  569.90 4326.41    NO

   3000.   0.5368        1     1.5    1.7   769.5  768.53  584.71 4647.55    NO

   3500.   0.4858        2     2.0    2.2   640.0  586.30  494.16  459.40    NO

   4000.   0.4783        2     2.0    2.2   640.0  586.30  549.96  524.02    NO

   4500.   0.4582        2     1.5    1.7   769.5  768.53  620.80  606.10    NO

   5000.   0.4438        2     1.5    1.7   769.5  768.53  674.43  672.02    NO

MAXIMUM 1‐HR CONCENTRATION AT OR BEYOND    20. M:

   1072.    1.007        1     2.0    2.2   640.0  586.30  265.84  544.88    NO

  DWASH=   MEANS NO CALC MADE (CONC = 0.0)

  DWASH=NO MEANS NO BUILDING DOWNWASH USED

  DWASH=HS MEANS HUBER‐SNYDER DOWNWASH USED

  DWASH=SS MEANS SCHULMAN‐SCIRE DOWNWASH USED

  DWASH=NA MEANS DOWNWASH NOT APPLICABLE, X<3*LB

      ***************************************

      *** SUMMARY OF SCREEN MODEL RESULTS ***

      ***************************************

  CALCULATION        MAX CONC    DIST TO   TERRAIN

   PROCEDURE        (UG/M**3)    MAX (M)    HT (M)

 ‐‐‐‐‐‐‐‐‐‐‐‐‐‐    ‐‐‐‐‐‐‐‐‐‐‐   ‐‐‐‐‐‐‐‐‐   ‐‐‐‐‐‐‐

SIMPLE TERRAIN       1.007         1072.        0.

***************************************************

** REMEMBER TO INCLUDE BACKGROUND CONCENTRATIONS **

***************************************************
Oglethorpe Power Corporation | Title V Significant Modification with Construction

Trinity Consultants D-1

APPENDIX D. EPD SIP FORMS

Georgia EPD Expedited Permitting Program - Application For Entry To Program For Air Permits – July 2017 Page 2 of 2 

2. Applying For Which Type Of Permit: (Please Check Appropriate Box) 

Expedited Review Fees for Air Permits

Permit Type – Please Check One Expedited Review 

Fee*

Generic Permit: Concrete Batch Plant – Minor Source $1,000

Generic Permit: Concrete Batch Plant – Synthetic Minor 

Source

$1,500

Generic Permit: Hot Mix Asphalt Plant – Synthetic Minor 

Source

$2,000

Minor Source Permit (or Amendment) $3,000

Synthetic Minor Permit (or Amendment) $4,000

Major Source SIP Permit not subject to PSD or 112(g) $6,000

Title V 502(b)(10) Permit Amendment $4,000

Title V Minor Modification with Construction $4,000

Title V Significant Modification $6,000

Major Source SIP Permit subject to 112(g) but not 

subject to PSD

$15,000

PSD Permit (or Amendment) not subject to NAAQS 

and/or PSD Increment Modeling

$15,000

PSD Permit (or Amendment) subject to NAAQS and/or 

PSD Increment Modeling but not subject to Modeling for 

PM2.5, NO2, or SO2

$20,000

PSD Permit (or Amendment) subject to NAAQS and/or 

PSD Increment Modeling for PM2.5, NO2, or SO2

$25,000

PSD Permit (or Amendment) subject to NAAQS and/or 

PSD Increment Modeling for PM2.5, NO2, or SO2 and also 

impacting a Class I Area

$30,000

* Do not send fee payment with this form. Upon acceptance of application for the 

expedited permit program, EPD will notify you by phone. Fees must be paid via 

check to “Georgia Department of Natural Resources” within five (5) business days of 

acceptance.

3. Comments. 

This section is optional. Applicants may use this field to include specific comments or requests for EPD 

consideration. For example, the applicant may use this field to request a public hearing or to remind EPD of 

review time needs and/or expectations that may differ from the time frames in the procedures. 

Georgia SIP Application Form 1.00, rev. February 2019 Page 2 of 5 

6. Reason for Application: (Check all that apply)

 New Facility (to be constructed) Revision of Data Submitted in an Earlier Application

 Existing Facility (initial or modification application) Application No.: 

 Permit to Construct Date of Original 

 Permit to Operate Submittal: 

 Change of Location

 Permit to Modify Existing Equipment: Affected Permit No.: 4911-149-0006-V-05-0

7. Permitting Exemption Activities (for permitted facilities only):

Have any exempt modifications based on emission level per Georgia Rule 391-3-1-.03(6)(i)(3) been performed at the 

facility that have not been previously incorporated in a permit?

 No Yes, please fill out the SIP Exemption Attachment (See Instructions for the attachment download)

8. Has assistance been provided to you for any part of this application?

 No Yes, SBAP Yes, a consultant has been employed or will be employed.

If yes, please provide the following information: 

Name of Consulting Company: Trinity Consultants

Name of Contact: Justin Fickas

Telephone No.: 404-751-0228 Fax No.: 678-441-9978

Email Address: jfickas@trinityconsultants.com

Mailing Address: Street: 3495 Piedmont Road Building 10, Suite 905 

City: Atlanta State: GA Zip: 30305

Describe the Consultant’s Involvement: 

Preparation of application.

9. Submitted Application Forms: Select only the necessary forms for the facility application that will be submitted. 

No. of Forms Form

1 2.00 Emission Unit List

1 2.01 Boilers and Fuel Burning Equipment

 2.02 Storage Tank Physical Data

 2.03 Printing Operations

 2.04 Surface Coating Operations

 2.05 Waste Incinerators (solid/liquid waste destruction)

 2.06 Manufacturing and Operational Data

1 3.00 Air Pollution Control Devices (APCD)

 3.01 Scrubbers

 3.02 Baghouses & Other Filter Collectors

 3.03 Electrostatic Precipitators

1 4.00 Emissions Data

1 5.00 Monitoring Information

 6.00 Fugitive Emission Sources

1 7.00 Air Modeling Information

10. Construction or Modification Date

Estimated Start Date: December 1, 2020
Georgia SIP Application Form 1.00, rev. February 2019 Page 3 of 5 

11. If confidential information is being submitted in this application, were the guidelines followed in the 

“Procedures for Requesting that Submitted Information be treated as Confidential”?

 No Yes 

12. New Facility Emissions Summary

Criteria Pollutant New Facility

Potential (tpy) Actual (tpy)

Carbon monoxide (CO) 

Nitrogen oxides (NOx) 

Particulate Matter (PM) (filterable only) 

PM <10 microns (PM10) 

PM <2.5 microns (PM2.5) 

Sulfur dioxide (SO2) 

Volatile Organic Compounds (VOC) 

Greenhouse Gases (GHGs) (in CO2e) 

Total Hazardous Air Pollutants (HAPs) 

Individual HAPs Listed Below:

 

 

 

 

 

 

13. Existing Facility Emissions Summary

Criteria Pollutant Current Facility After Modification

Potential (tpy) Actual (tpy) Potential (tpy) Actual (tpy)

Carbon monoxide (CO) 86.0 < 86 86.0 < 86.0

Nitrogen oxides (NOx) 179.6 < 179.6 179.6 < 179.6

Particulate Matter (PM) (Total) 168 < 168 173 < 173 

PM <10 microns (PM10) (Total) 167 < 167 173 < 173 

PM <2.5 microns (PM2.5) (Total) 161 < 161 166 < 166 

Sulfur dioxide (SO2) 9.60 < 9.60 9.91 < 9.91

Volatile Organic Compounds (VOC) 41.5 < 41.5 42.8 < 42.8

Greenhouse Gases (GHGs) (in CO2e) 1,903,064 < 1,903,064 1,965,365 < 1,965,365

Total Hazardous Air Pollutants (HAPs) 7.78 < 7.78 8.27 < 8.27

Individual HAPs Listed Below:

Maximum Single HAP (Formaldehyde) 1.97 < 1.97 2.10 < 2.10

 
Georgia SIP Application Form 1.00, rev. February 2019 Page 4 of 5 

14. 4-Digit Facility Identification Code:

SIC Code: 4911 SIC Description: Electric Services

NAICS Code: 221112 NAICS Description: Electric power generation, fossil fuel

15. Description of general production process and operation for which a permit is being requested. If 

necessary, attach additional sheets to give an adequate description. Include layout drawings, as necessary, 

to describe each process. References should be made to source codes used in the application.

See attached narrative.

16. Additional information provided in attachments as listed below:

Attachment A - Area Map and Process Flow Diagram

Attachment B - Emission Calculations

Attachment C - Toxics Impact Analysis

Attachment D - SIP Permit Application Forms

Attachment E -

Attachment F -

17. Additional Information: Unless previously submitted, include the following two items:

 Plot plan/map of facility location or date of previous submittal: See Appendix A

 Flow Diagram or date of previous submittal: See Appendix A

18. Other Environmental Permitting Needs:

Will this facility/modification trigger the need for environmental permits/approvals (other than air) such as Hazardous 

Waste Generation, Solid Waste Handling, Water withdrawal, water discharge, SWPPP, mining, landfill, etc.?

 No Yes, please list below:
Georgia SIP Application Form 1.00, rev. February 2019 Page 5 of 5 

19. List requested permit limits including synthetic minor (SM) limits. 

See attached narrative.

20. Effective March 1, 2019, permit application fees will be assessed. The fee amount varies based on type of 

permit application. Application acknowledgement emails will be sent to the current registered fee contact in the 

GECO system. If fee contacts have changed, please list that below:

Fee Contact name: Courtney Adcock

Fee Contact email address: courtney.adcock@opc.com

Fee Contact phone number: 770-270-7678

Fee invoices will be created through the GECO system shortly after the application is received. It is the 

applicant’s responsibility to access the facility GECO account, generate the fee invoice, and submit payment 

within 10 days after notification. 
Georgia SIP Application Form 2.00, rev. June 2005 Page 1 of 1 

Facility Name: Chattahoochee Energy Facility Date of Application: June 2020

FORM 2.00 – EMISSION UNIT LIST

Emission 

Unit ID Name Manufacturer and Model Number Description

CT8A Combustion Turbine Unit 8A Siemens-Westinghouse Model V84.3a2 Combustion Turbine

DB8A HRSG 

Duct Burner for Turbine 8A Forney Duct Burner w/Low NOx burner to supplement HRSG

CT8B Combustion Turbine Unit 8A Siemens-Westinghouse Model V84.3a2 Combustion Turbine

DB8B HRSG 

Duct Burner for Turbine 8A Forney Duct Burner w/Low NOx burner to supplement HRSG
Georgia SIP Application Form 2.01, rev. June 2005 Page 1 of 2 

Facility Name: Chattahoochee Energy Facility Date of Application: June 2020

FORM 2.01 – BOILERS AND FUEL BURNING EQUIPMENT

Emission 

Unit ID Type of Burner Type of Draft1

Design Capacity 

of Unit

(MMBtu/hr Input)

Percent 

Excess 

Air

Dates

Date & Description of Last Modification

Construction Installation

CCCT8A 

Combined Combustion 

Turbine and Duct Burner

(CT8A and DB8A) 

N/A 1,995 MMBtu/hr2 2002 May 2002 N/A

CCCT8B 

Combined Combustion 

Turbine and Duct Burner

(CT8B and DB8B) 

N/A 1,995 MMBtu/hr2 2002 May 2002 N/A

 

 

 

 

 

 

1 This column does not have to be completed for natural gas only fired equipment. 

2 1,995 MMBtu/hr represents the maximum short-term heat input capacity of each CCCT once the proposed project is complete. The projected actual heat input capacity is estimated to 

be 15.1 million MMBtu/yr per CCCT.
Georgia SIP Application Form 2.01, rev. June 2005 Page 2 of 2 

Facility Name: Chattahoochee Energy Facility Date of Application: June 2020

FUEL DATA

Emission 

Unit ID Fuel Type

Potential Annual Consumption Hourly 

Consumption

Heat

Content Percent Sulfur Percent Ash in Solid Fuel

Total Quantity Percent Use by Season

Max. Avg. Min. Avg. Max. Avg. Max. Avg. Amount Units Ozone Season

May 1 - Sept 30

Non-ozone 

Season

Oct 1 - Apr 30

CCCT8A Natural Gas 16.5 Million 

MMBtu/yr 

1,995 

MMBtu/hr Varies

~1,020 

MMBtu/

MMscf

~1,020 

MMBtu/

MMscf

CCCT8B Natural Gas 16.5 Million 

MMBtu/yr

1,995 

MMBtu/hr Varies

~1,020 

MMBtu/

MMscf

~1,020 

MMBtu/

MMscf

Fuel Supplier Information

Fuel Type Name of Supplier Phone Number Supplier Location

Address City State Zip

Pipeline Quality 

Natural Gas 
Georgia SIP Application Form 3.00, rev. June 2005 Page 1 of 2 

Facility Name: Chattahoochee Energy Facility Date of Application: June 2020

Form 3.00 – AIR POLLUTION CONTROL DEVICES - PART A: GENERAL EQUIPMENT INFORMATION

APCD

Unit ID

Emission 

Unit ID 

APCD Type

(Baghouse, ESP, 

Scrubber etc) 

Date

Installed

Make & Model Number

(Attach Mfg. Specifications & Literature) 

Unit Modified from Mfg 

Specifications?

Gas Temp. °F Inlet Gas 

Flow Rate

Inlet Outlet (acfm) 

SCR8A 

CCCT8A

(CT8A and 

DB8A 

Combined)

Selective 

Catalytic 

Reduction 

2016 Cormetech, Custom Built N/A 

Stack 

Outlet is 

199.5°F 

< 1,044,320

SCR8B 

CCCT8B

(CT8B and 

DB8B 

Combined)

Selective 

Catalytic 

Reduction 

2016 Cormetech, Custom Built N/A 

Stack 

Outlet is 

199.5°F 

< 1,044,320

CO8A 

CCCT8A

(CT8A and 

DB8A 

Combined)

Catalytic 

Oxidation 2002 Engelhard PES, Custom Built N/A 

Stack 

Outlet is 

199.5°F 

< 1,044,320

CO8B 

CCCT8B

(CT8B and 

DB8B 

Combined)

Catalytic 

Oxidation 2002 Engelhard PES, Custom Built N/A 

Stack 

Outlet is 

199.5°F 

< 1,044,320

 

 

 

 

 

 

 

 
Georgia SIP Application Form 3.00, rev. June 2005 Page 2 of 2 

Facility Name: Chattahoochee Energy Facility Date of Application: June 2020

Form 3.00 – AIR POLLUTION CONTROL DEVICES – PART B: EMISSION INFORMATION

APCD

Unit ID Pollutants Controlled

Percent Control 

Efficiency Inlet Stream To APCD Exit Stream From APCD Pressure Drop 

Across Unit

Design Actual lb/hr (Inches of water) Method of 

Determination lb/hr Method of Determination

SCR8A NOX ~85% < 85% ~137 ~20.5 CEMS N/A

SCR8B NOX ~85% < 85% ~137 ~20.5 CEMS N/A

CO8A CO ~85% < 85% ~65.4 ~9.8 CEMS N/A

CO8B CO ~85% < 85% ~65.4 ~9.8 CEMS N/A

 

 

 

 

 

 

 

 

 

 

 

 

 
Georgia SIP Application Form 4.00, rev. June 2011 Page 1 of 1 

Facility Name: Chattahoochee Energy Facility Date of Application: June 2020

FORM 4.00 – EMISSION INFORMATION

Emission 

Unit ID

Air Pollution 

Control 

Device ID

Stack

ID Pollutant Emitted

Emission Rates

Hourly Actual 

Emissions

(lb/hr)

Hourly 

Potential 

Emissions

(lb/hr)

Actual 

Annual 

Emission

(tpy)

Potential 

Annual 

Emission

(tpy)

Method of 

Determination

CCCT8A SCR8A ST8A 

See emission calculations

in Appendix B: Emission 

Calculations

CCCT8B SCR8B ST8B 

See emission calculations 

in Appendix B: Emission 

Calculations

CCCT8A CO8A ST8A 

See emission calculations

in Appendix B: Emission 

Calculations

CCCT8B CO8B ST8B 

See emission calculations 

in Appendix B: Emission 

Calculations

 

 

 

 
Georgia SIP Application Form 5.00, rev. June 2005 Page 1 of 1 

Facility Name: Chattahoochee Energy Facility Date of Application: June 2020

FORM 5.00 MONITORING INFORMATION

Emission 

Unit ID/

APCD ID

Emission Unit/APCD 

Name

Monitored Parameter 

Monitoring Frequency Parameter Units

CCCT8A 

Combined Combustion 

Turbine and Duct 

Burner (CT8A and 

DB8A)

CO ppmvd @ 15% O2 3-Hour Rolling Average

CCCT8B 

Combined Combustion 

Turbine and Duct 

Burner (CT8B and 

DB8B)

CO ppmvd @ 15% O2 3-Hour Rolling Average

CCCT8A 

Combined Combustion 

Turbine and Duct 

Burner (CT8A and 

DB8A)

NOX ppmvd @ 15% O2 4-Hour Rolling Average

CCCT8B 

Combined Combustion 

Turbine and Duct 

Burner (CT8B and 

DB8B)

NOX ppmvd @ 15% O2 4-Hour Rolling Average

 

 

 

 

 

 

 

 

 

 

Comments:

OPC requests that NSPS Subpart GG and NSPS Subpart Dc Monitoring & Testing conditions be removed since the 

facility will no longer be subject to these subparts after the proposed project is completed. OPC also requests that NSPS 

Subpart KKKK related Monitoring & Testing conditions be added as the combined cycle combustion turbines will be 

subject to that Subpart once the proposed project is completed. 
Georgia SIP Application Form 7.00, rev. June 2005 Page 1 of 2 

Facility Name: Chattahoochee Energy Facility Date of Application: June 2020

FORM 7.00 – AIR MODELING INFORMATION: Stack Data

Stack ID Emission 

Unit ID(s)

Stack Information Dimensions of largest 

Structure Near Stack Exit Gas Conditions at Maximum Emission Rate

Height 

Above 

Grade (ft)

Inside 

Diameter 

(ft)

Exhaust 

Direction 

Height

(ft)

Longest 

Side (ft)

Velocity

(ft/sec)

Temperature 

(°F)

Flow Rate (acfm)

Average Maximum

ST8A CT8A and 

DB8B 130 16.5 Unobstructed Up N/A 81.4 199.5 < 1,044,320 1,044,320

ST8B CT8A and 

DB8B 130 16.5 Unobstructed Up N/A 81.4 199.5 < 1,044,320 1,044,320

 

 

 

 

 

 

NOTE: If emissions are not vented through a stack, describe point of discharge below and, if necessary, include an attachment. List the attachment in Form 1.00 

General Information, Item 16.
Georgia SIP Application Form 7.00, rev. June 2005 Page 2 of 2 

Facility Name: Chattahoochee Energy Facility Date of Application: June 2020

FORM 7.00 AIR MODELING INFORMATION: Chemicals Data

Chemical

Potential 

Emission Rate 

(lb/hr)

Toxicity Reference MSDS 

Attached

See Appendix C: Toxics Impact Analysis 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
APPENDIX C – FEMA FIRMETTE FLOOD MAP 
USGS The National Map: Orthoimagery. Data refreshed April 2020

National Flood Hazard Layer FIRMette

0 250 500 1,000 1,500 2,000

Feet

Ü

SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT

SPECIAL FLOOD

HAZARD AREAS

Without Base Flood Elevation (BFE)

Zone A, V, A99

With BFE or DepthZone AE, AO, AH, VE, AR

Regulatory Floodway

0.2% Annual Chance Flood Hazard, Areas

of 1% annual chance flood with average

depth less than one foot or with drainage

areas of less than one square mileZone X

Future Conditions 1% Annual

Chance Flood HazardZone X

Area with Reduced Flood Risk due to

Levee. See Notes.Zone X

Area with Flood Risk due to LeveeZone D

NO SCREENArea of Minimal Flood Hazard Zone X

Area of Undetermined Flood HazardZone D

Channel, Culvert, or Storm Sewer

Levee, Dike, or Floodwall

Cross Sections with 1% Annual Chance

17.5 Water Surface Elevation

Coastal Transect

Coastal Transect Baseline

Profile Baseline

Hydrographic Feature

Base Flood Elevation Line (BFE)

Effective LOMRs

Limit of Study

Jurisdiction Boundary

Digital Data Available

No Digital Data Available

Unmapped

This map complies with FEMA's standards for the use of

digital flood maps if it is not void as described below.

The basemap shown complies with FEMA's basemap

accuracy standards

The flood hazard information is derived directly from the

authoritative NFHL web services provided by FEMA. This map

was exported on 9/15/2020 at 8:27 PM and does not

reflect changes or amendments subsequent to this date and

time. The NFHL and effective information may change or

become superseded by new data over time.

This map image is void if the one or more of the following map

elements do not appear: basemap imagery, flood zone labels,

legend, scale bar, map creation date, community identifiers,

FIRM panel number, and FIRM effective date. Map images for

unmapped and unmodernized areas cannot be used for

regulatory purposes.

Legend

OTHER AREAS OF

FLOOD HAZARD

OTHER AREAS

GENERAL

STRUCTURES

OTHER

FEATURES

MAP PANELS

8

B

20.2

The pin displayed on the map is an approximate

point selected by the user and does not represent

an authoritative property location.

1:6,000

85°2'37"W 33°24'33"N

85°2'W 33°24'3"N
APPENDIX D – USFWS IPAC DOCUMENTATION 
▪

April 13, 2020

United States Department of the Interior

FISH AND WILDLIFE SERVICE

Georgia Ecological Services Field Office

355 East Hancock Avenue

Room 320

Athens, GA 30601

Phone: (706) 613-9493 Fax: (706) 613-6059

In Reply Refer To:

Consultation Code: 04EG1000-2020-SLI-1928

Event Code: 04EG1000-2020-E-03553 

Project Name: CEF TPU1/LLTD Project

Subject: List of threatened and endangered species that may occur in your proposed project 

location, and/or may be affected by your proposed project

To Whom It May Concern:

This list identifies threatened, endangered, proposed and candidate species, as well as critical 

habitat, that may be affected by your proposed project. This list may change before your project 

is completed. Under 50 CFR 402.12(e) of the regulations implementing section 7 of the Act, the 

accuracy of this list should be verified after 90 days. The Service recommends that verification 

be completed by visiting the ECOS-IPaC website at regular intervals during project planning and 

implementation.

Bald and golden eagles are protected under the Bald and Golden Eagle Protection Act (16 U.S.C. 

668 et seq.). Projects affecting these species may require development of an eagle conservation 

plan (http://www.fws.gov/windenergy/eagle_guidance.html).

Wind energy projects should follow the wind energy guidelines http://www.fws.gov/windenergy/ 

for minimizing impacts to migratory birds and bats.

Guidance for minimizing impactsof communcation towers on migratory birds can be found 

under the "Bird Hazards" tab at: www.fws.gov/migratorybirds.

Attachment(s):

Official Species List
04/13/2020 Event Code: 04EG1000-2020-E-03553   1

Official Species List

This list is provided pursuant to Section 7 of the Endangered Species Act, and fulfills the 

requirement for Federal agencies to "request of the Secretary of the Interior information whether 

any species which is listed or proposed to be listed may be present in the area of a proposed 

action".

This species list is provided by:

Georgia Ecological Services Field Office

355 East Hancock Avenue

Room 320

Athens, GA 30601

(706) 613-9493
04/13/2020 Event Code: 04EG1000-2020-E-03553   2

Project Summary

Consultation Code: 04EG1000-2020-SLI-1928

Event Code: 04EG1000-2020-E-03553

Project Name: CEF TPU1/LLTD Project

Project Type: POWER GENERATION

Project Description: Software and mechanical internal upgrades

Project Location:

Approximate location of the project can be viewed in Google Maps: https://

www.google.com/maps/place/33.408564180973855N85.03283323029991W

Counties: Heard, GA
04/13/2020 Event Code: 04EG1000-2020-E-03553   3

1.

Endangered Species Act Species

There is a total of 0 threatened, endangered, or candidate species on this species list.

Species on this list should be considered in an effects analysis for your project and could include 

species that exist in another geographic area. For example, certain fish may appear on the species 

list because a project could affect downstream species.

IPaC does not display listed species or critical habitats under the sole jurisdiction of NOAA 

Fisheries , as USFWS does not have the authority to speak on behalf of NOAA and the 

Department of Commerce.

See the "Critical habitats" section below for those critical habitats that lie wholly or partially 

within your project area under this office's jurisdiction. Please contact the designated FWS office 

if you have questions.

NOAA Fisheries, also known as the National Marine Fisheries Service (NMFS), is an 

office of the National Oceanic and Atmospheric Administration within the Department of 

Commerce.

Critical habitats

THERE ARE NO CRITICAL HABITATS WITHIN YOUR PROJECT AREA UNDER THIS OFFICE'S 

JURISDICTION.

1
APPENDIX E – NWI MAP 
Wetlands

Source: Esri, Maxar, GeoEye, Earthstar Geographics, CNES/Airbus DS,

USDA, USGS, AeroGRID, IGN, and the GIS User Community

Wetlands

Estuarine and Marine Deepwater

Estuarine and Marine Wetland

Freshwater Emergent Wetland

Freshwater Forested/Shrub Wetland

Freshwater Pond

Lake

Other

Riverine

September 16, 2020

0 0.25 0.5 1 mi

0 0.375 0.75 1.5 km

1:28,871

This page was produced by the NWI mapper

National Wetlands Inventory (NWI)

This map is for general reference only. The US Fish and Wildlife 

Service is not responsible for the accuracy or currentness of the 

base data shown on this map. All wetlands related data should 

be used in accordance with the layer metadata found on the 

Wetlands Mapper web site.