Document ID: EPA-R07-OAR-2012-0158-0023
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2012-03-02T05:00Z

Technical Support Document
                       Nebraska Regional Haze Submittal
                                       
                                       
                                 Prepared by:
                             Chrissy Wolfersberger
                      Environmental Protection Specialist
                U. S. Environmental Protection Agency Region 7
                                       
                                 February 2012

Table of Contents
I. Summary of Environmental Protection Agency (EPA) action		Page 3
II. State regional haze rulemaking						Page 3
III. EPA's evaluation of Nebraska's State Implementation Plan (SIP)		Page 3
      a. Identification of areas							Page 3
      b. Baseline and natural visibility conditions					Page 6
      c. Reasonable progress goals (RPG)						Page 7
      d. Long-term strategy (LTS)							Page 7
           i. Consultation with other States					Page 8
           1. South Dakota  -  Badlands and Wind Cave
           2. Colorado  -  Rocky Mountain and Great Sand Dunes
           3. Minnesota  -  Voyageurs and Boundary Waters
           4. Oklahoma  -  Wichita Mountains
           5. Missouri  -  Mingo and Hercules Glades
      e. Best Available Retrofit Technology (BART)				Page 11
           i. BART-eligible sources						Page 11
           ii. BART-subject sources						Page 13
           iii. Particulate Matter (PM) evaluation					Page 14
           iv. BART determinations							Page 14
           1. Omaha Public Power District (OPPD)  -  Nebraska City Station
           2. Nebraska Public Power District (NPPD)  -  Gerald Gentleman Station
           v. BART summary and enforceability					Page 28
      f. Monitoring strategy							Page 28
      g. Emissions inventory							Page 29
      h. Federal Land Manager (FLM) consultation				Page 30
      i. SIP revisions and five year progress reports				Page 32

Tables
      Table 1	State of Nebraska's contributions to visibility impairment at Class I areas
      Table 2	South Dakota Uniform Rate of Progress (URP) and RPGs
      Table 3	Facilities with BART-eligible units in Nebraska
      Table 4	BART-eligible facilities determined not to be subject to BART
      Table 5	BART-subject facilities in Nebraska
      Table 6	NOx control technology effectiveness, NCS Unit 1
      Table 7	Cost of NOx control options, NCS Unit 1
      Table 8	Visibility improvement analysis, NCS Unit 1
      Table 9 	Costs for visibility improvement, NCS Unit 1
      Table 10 	SO2 control technology effectiveness, NCS Unit 1
      Table 11	Cost of SO2 control options, NCS Unit 1
      Table 12	NOx control technology effectiveness, GGS Units 1 and 2
Table 13	Cost of NOx control options, GGS Units 1 and 2
      Table 14	Visibility analysis, NPPD GGS Units 1 and 2
      Table 15	Costs for visibility improvement, GGS Units 1 and 2
      Table 16	SO2 control technology effectiveness, GGS Units 1 and 2
      Table 17 	Cost of SO2 control options, GGS Units 1 and 2
      Table 18 	Cost of SO2 control and visibility benefit, GGS Units 1 and 2
      Table 19	Range of GGS dry scrubber cost effectiveness
      Table 20	Summary of BART determinations
      Table 21 	2002 Nebraska emissions
      Table 22	2018 Nebraska projected emissions

Figures

      Figure 1	Map of the 156 mandatory Class I Federal areas
      Figure 2	Geographic area of Regional Planning Organizations

Appendices

	Appendix A	EPA's analysis of cost estimates for flue gas desulfurization (FGD) at GGS 
      Appendix B 	GGS emissions 
      Appendix C	GGS FGD cost analysis spreadsheet
      
      

I. Summary of EPA's action
EPA is proposing a partial approval and a partial disapproval of Nebraska's State Implementation Plan (SIP) for Regional Haze, received by EPA on July 13, 2011. Specifically, we are proposing to disapprove the sulfur dioxide (SO2) best available retrofit technology (BART) determination for Nebraska Public Power Station (NPPD), Gerald Gentleman Station (GGS), Units 1 and 2. We are proposing to disapprove this BART determination because it does not comply with our regional haze regulations and guidance. We are also proposing to disapprove the long term strategy (LTS), insofar as it relies on this deficient BART determination. To correct the deficiencies identified in these proposed disapprovals, we are also proposing a partial Federal Implementation Plan (FIP), relying on the Transport Rule as an alternative to BART for SO2 emissions from the GGS units. This limited FIP would satisfy the SO2 BART requirement for these units and remedy the deficiency in Nebraska's LTS.  
         
EPA is proposing a partial approval on the remaining elements of Nebraska' regional haze plan, including the BART determinations for Omaha Public Power District (OPPD), the NOx BART determination for Gerald Gentleman Station Units 1 and 2, emissions inventory, and monitoring strategy, as described below.

II. State regional haze rulemaking
The Nebraska Department of Environmental Quality (NDEQ) provided public notice of the opportunity to comment on the regional haze SIP on December 6, 2010, via notice in the Omaha World Herald and on NDEQ's website. Nebraska also notified the FLMs, and the States of Colorado, South Dakota, Missouri, Minnesota, and Oklahoma of the opportunity for comment on the draft SIP.
         
Nebraska held a public hearing regarding the SIP on January 21, 2011. Comments were received from the State of Colorado, the National Parks Conservation Association (NPCA), EPA Region 7, the FLMs (National Park Service, Fish and Wildlife Service, Forest Service), and the Twin Platte Natural Resource District. These comments and Nebraska's responses are available in Appendix 3 of the SIP.  Specific comments are mentioned throughout this technical support document (TSD). 
         
III. EPA's evaluation of Nebraska's State Implementation Plan 

a. Identification of affected Class I areas
States are required to identify each Class I area located within the State and each Class I area located outside the State which is affected by emissions from within the State.  
            
Although there are no Class I areas hosted by the State of Nebraska, the State is still required to identify those Class I areas which may be affected by emissions from Nebraska sources. 

           Figure 1: Map of the 156 mandatory Class I Federal areas
Because the pollutants that lead to regional haze can originate from sources located across broad geographic areas, EPA encouraged the States and Tribes to address visibility impairment from a regional perspective. Five regional planning organizations (RPOs) were developed to address regional haze and related issues. These organizations evaluated technical information to better understand how their States and Tribes impact visibility at Class I areas across the country, and pursued the development of regional strategies to reduce emissions of pollutants leading to regional haze issues. 
         
Nebraska participated in the planning efforts of the Central Regional Air Planning Association (CENRAP). This RPO includes nine states - Nebraska, Iowa, Oklahoma, Texas, Minnesota, Iowa, Missouri, Arkansas, and Louisiana. CENRAP and its contractors provided air quality modeling to the States to help them determine whether sources located within the State can be reasonably expected to cause or contribute to visibility impairment in a Class I area.  The modeling conducted relied on baseline year (2002) and future planning year (2018) emissions inventories that were prepared with participation from each of the CENRAP states. States relied on these inventories to develop control strategies to meet the visibility improvement goals of the regional haze rule and to develop their SIPs.  
            

      
        Figure 2: Geographical area of Regional Planning Organizations
The State of Nebraska relied upon the regional modeling work provided by CENRAP for determining the impact that sources within the State might have on Class I areas in the region and beyond. The modeling was based on PM Source Apportionment Technology (PSAT) for the Comprehensive Air Quality Model with extensions (CAMx) photochemical model. A detailed description of this modeling can be found in Chapter 9 and appendix 9.1 and 9.2 of the SIP. This tool was used to estimate Nebraska's contribution to visibility impairment at the Class I areas in Arkansas, Colorado, Minnesota, Missouri, Oklahoma, Texas, and South Dakota.
In EPA's review of Nebraska's SIP, we accessed the PSAT tool from the CENRAP website.  In attempting to recreate the charts that Nebraska presented in its SIP using the PSAT tool, we came up with slightly different results. The results presented below are from the August 27, 2007 version of the tool, which are similar, but not identical, to the results presented in the Nebraska SIP.  2002 and 2018 figures presented below are PSAT projected results for Nebraska, in terms of absolute extinction. 
According to the PSAT modeling, contributions from Nebraska sources for the worst 20% days were highest at the South Dakota Class I areas. For the 2002 baseline year, Nebraska sources were projected to contribute 7.81% of visibility impairment at Badlands, and 7% at Wind Cave.  In 2018, the projected contribution was reduced to 5.89% and 5.24%, respectively. However, it is critical to understand that the 2018 projections were developed assuming presumptive levels of control on Nebraska BART sources, which ultimately the State did not require. For that reason, it is likely that Nebraska sources would have a larger contribution to 2018 visibility impairment than what is presented in table 1.
Nebraska's contribution to all other Class I areas was considerably less, and in no case greater than 1.9%. 
Table 1: State of Nebraska's contribution to visibility impairment at Class I areas
                                     State
                                 Class I area
             Class I area total extinction (20% worst days) (1/Mm)
                                Nebraska source
                              contribution (1/Mm)
       Percentage contribution to visibility impairment from NE sources

                                     2002
                                     2018
                                     2002
                                     2018
                                     2002
                                     2018
South Dakota
Badlands National Park
                                     44.87
                                     41.20
                                     3.51
                                     2.42
                                     7.81%
                                     5.89%
South Dakota
Wind Cave National Park
                                     40.71
                                     37.16
                                     2.85
                                     1.95
                                     7.00%
                                     5.24%
Colorado
Great Sand Dunes National Park
                                     27.88
                                     26.77
                                     0.52
                                     0.39
                                     1.87%
                                     1.46%
Colorado
Rocky Mountain National Park
                                     32.13
                                     29.41
                                     0.57
                                     0.40
                                     1.76%
                                     1.35%
Minnesota
Boundary Waters Wilderness Area
                                     61.33
                                     53.32
                                     1.04
                                     0.79
                                     1.70%
                                     1.49%
Texas
Guadalupe Mountains National Park
                                     47.80
                                     44.43
                                     0.72
                                     0.62
                                     1.51%
                                     1.40%
Minnesota
Voyagers National Park
                                     59.50
                                     52.10
                                     0.86
                                     0.64
                                     1.45%
                                     1.24%
Oklahoma
Wichita Mountains Wilderness Area
                                    100.03
                                     75.56
                                     1.11
                                     0.81
                                     1.11%
                                     1.08%
Missouri
Hercules-Glades Wilderness Area
                                    140.05
                                     92.49
                                     1.34
                                     0.99
                                     0.95%
                                     1.07%
Missouri
Mingo Wilderness Area
                                    159.83
                                     99.24
                                     1.26
                                     0.85
                                     0.79%
                                     0.86%
Arkansas
Caney Creek Wilderness Area
                                    133.93
                                     85.84
                                     1.06
                                     0.71
                                     0.79%
                                     0.83%
Texas
Big Bend National Park 
                                     47.79
                                     44.23
                                     0.29
                                     0.24
                                     0.61%
                                     0.55%
Arkansas
Upper Buffalo Wilderness Area
                                    131.79
                                     86.16
                                     0.66
                                     0.44
                                     0.50%
                                     0.51%

b. Baseline and natural visibility conditions: 40 CFR 51.308(d)(2)
States that host Class I areas are required to estimate the baseline, natural and current visibility conditions of those Class I areas. Nebraska does not host a Class I area, therefore, it is not required to estimate these metrics. 

c. Reasonable Progress Goals: 40 CFR 51.308(d)(1)
The RHR requires States and Tribes to establish a reasonable progress goal (RPG) for each Class I area within the state. The RPG is measured in deciviews and is to provide for reasonable progress towards achieving natural visibility conditions during the first implementation period (through 2018). RPGs should represent an improvement in visibility for the most impaired days, and ensure no degradation in visibility on the least impaired days. 
Nebraska does not have a Class I area within the state and therefore is not required to establish a RPG. States hosting Class I areas have established RPGs, and have made assessments regarding whether emission reductions are needed from sources in Nebraska in order to meet their RPG. Specific State goals and Nebraska's effect on meeting them are described in further detail in the LTS consultation section, below. 
d. Long-Term Strategy: 40 CFR 51.308(d)(3)
States must submit a long-term strategy that addresses regional haze visibility impairment for each Class I area within the State and for each Class I area located outside the State which may be affected by emissions from the State. The long-term strategy must include enforceable emissions limitations, compliance schedules, and other measures as necessary to achieve the reasonable progress goals established by States having Class I areas.
         
States must consider, at a minimum, the following factors in developing their long-term strategy: 
   * Emission reductions due to ongoing air pollution control programs, including measures to address reasonably attributable visibility impairment;
   * Measures to mitigate the impacts of construction activities;
   * Emissions limitations and schedules for compliance to achieve the reasonable progress goal;
   * Source retirement and replacement schedules;
   * Smoke management techniques for agricultural and forestry management purposes, including plans as currently exist within the State for these purposes;
   * Enforceability of emissions limitations and control measures; and
   * The anticipated net effect on visibility due to projected changes in point, area, and mobile source emissions over the period addressed by the long-term strategy.
         
Nebraska's LTS for the first implementation period addresses the emissions reductions from Federal, State, and local controls that take effect in the state from the end of the baseline period through 2018. As described elsewhere in this document, the changes in point, area, and mobile source emissions over the first implementation period (through 2018) were taken into account by CENRAP and the State in developing the emission inventory for 2018. 
         
Specifically, Nebraska considered the following Federal and State control measures when developing its LTS:
   * Clean Air Interstate Rule (CAIR). Although Nebraska was not included in the original CAIR rulemaking, the rule was a major component in the underlying assumptions used to determine source apportionment because of the reductions expected in neighboring states with Class I areas. 
   * Federal mobile source standards 
   * Tier 2 vehicle and low sulfur fuels
   * Locomotive and Marine engine rules
   * Small spark-ignition engine rules 
   * National Emission Standards for Hazardous Air Pollutants (NESHAP) and associated Maximum Achievable Control Technology (MACT) standards 
   * Nebraska's Prevention of Significant Deterioration (PSD) construction permitting program. Nebraska notes that the visibility protection provisions of PSD found at 40 CFR 52.21(o) have been incorporated into Title 129-Nebraska Air Quality Regulations at Chapter 19 Section 022. Section 40 CFR 52.21(p) requires notification and consultation with federal land managers (FLMs) of Class I areas which may be affected by emissions from a new source; these requirements under have been incorporated by reference into Title 129 at Chapter 19 Section 001.
         
Nebraska has fugitive dust regulations in Nebraska Title 129 - Chapter 32, which includes a provision applicable to construction activities. The rule requires the use of reasonable measures such as paving, cleaning, application of water, planting and maintenance of ground cover, and/or application of dust-free surfactants to prevent dust from becoming airborne such that it remains visible beyond the property boundary. Nebraska contends that construction activities are not expected to cause a significant impact to visibility, and did not require any additional measures to mitigate the impacts of construction activities for purposes of visibility improvement.
         
Nebraska also has regulations that address smoke management for agricultural and forestry management burns. Title 129 - Chapter 30 is a ban on open burning with some direct exceptions that include agriculture operations and parks management, and fires set for training purposes. Other types of exceptions are subject to approval by the NDEQ and the local fire authority. For purposes of forestry or land management, such burning is allowed provided it is conducted by a limited set of organizations approved by NDEQ. Nebraska contends that, based on the minimal impacts from burning, a more stringent smoke management plan is not needed for purposes of visibility protection at this time. 
         
The above programs are fully enforceable, provide for the mitigation of new source impacts through new source permitting programs, and reflect appropriate consideration of current programs and prospective changes in emissions. Enforceability of Nebraska's BART control measures are more fully described in section III (e) (v) of this TSD.

           i. Consultation on other States' RPGs
        Where Nebraska has emissions that are reasonably anticipated to contribute to visibility impairment in any mandatory Class I Federal area located in another State or States, it must consult with the other State(s) in order to develop coordinated emission management strategies. If Nebraska causes or contributes to impairment in a Class I area, it must demonstrate that it has included in its SIP all measures necessary to obtain its share of the emission reductions needed to meet the progress goal for the area.
        
        As mentioned previously, Nebraska participated in the CENRAP planning process, which provided the primary venue for State consultation and coordination on emission management strategies. Nebraska also says in the SIP that it notified the states of South Dakota, Oklahoma, Missouri and Colorado while its draft BART permits were open for public comment, proposing only control for NOx at the three BART-subject units in the State. It should be noted that although Nebraska participated as a member State in CENRAP, the greatest impacts from Nebraska sources occur in a Western Regional Area Partnership (WRAP) State  -  South Dakota. 

           1. South Dakota
           Nebraska asserts that is has a "minimal" impact on all Class I areas, and points out in its SIP that no State asked Nebraska for reductions in order to meet its RPGs. We disagree with the characterization of Nebraska's contribution as minimal, as PSAT modeling shows Nebraska sources contribute 7-8% of the total visibility impairment at the South Dakota Class I areas, and source-specific CALPUFF modeling shows that GGS has a maximum baseline impact at Badlands of 3.12 dv in 2003, and 2.59 dv at Wind Cave in 2002.
           
           South Dakota's reasonable progress goals, which are proposed for approval by EPA at the time of this writing, achieve less visibility improvement than the uniform rate of progress for the first implementation period. The reasonable progress goals for the 20% worst days fall short of the uniform rate of progress by 1.28 deciviews (dv) for Badlands and 1.34 dv at Wind Cave.
                        
         Table 2: South Dakota Uniform Rate of Progress (URP) and RPGs
                                  (deciviews)
                                 South Dakota
                                 Class I areas
                             2000 - 2004 baseline
                                20% worst days
                                     2018
                                      URP
                                 2064 natural
                                  conditions
                                     2018
                                  reductions
                                    needed
                                      RPG
                                    Deficit
Badlands
                                                                          17.14
                                                                          15.02
                                                                           8.06
                                                                           2.18
                                                                          16.30
                                                                           1.28
Wind Cave
                                                                         15.84 
                                                                          13.94
                                                                           7.71
                                                                           1.89
                                                                          15.28
                                                                           1.34

           Furthermore, the modeling used to estimate achievement of these goals assumed that a presumptive level of BART SO2 controls would be installed on Nebraska sources. Nebraska did not go on to require that level of control, and in fact required no SO2 controls, therefore, South Dakota may be even further away from meeting its RPGs than what the modeling predicted. 
           
           As described in detail in section III (e) (iv) (2) of this TSD, we propose to disapprove Nebraska's SO2 BART determination for GGS, and also propose to disapprove Nebraska's LTS insofar as it relied on this deficient BART determination. 
           
           
           
                        
           2. Colorado
           In a comment letter dated January 21, 2011, the Colorado Department of Public Health and Environment (CDPHE) notes that Gerald Gentleman Station has a visibility impact of greater than one deciview on Rocky Mountain National Park (RMNP). CDPHE reviewed the CALPUFF modeling, and noted that controls at Gerald Gentleman Station would provide visibility improvement at both RMNP and Great Sand Dunes National Park. They note that both NOx and SO2 controls appear to be cost effective.
           
           In comments dated June 23, 2009, CDPHE points out that GGS is the largest EGU in Nebraska at 1,365 MW, and has average SO2 emissions (31,135 tpy) that are more than half as much as all of the EGUs in Colorado combined. CDPHE questions why Nebraska would propose no SO2 controls, since such controls are regularly available, common controls for EGUs. CDPHE encourages Nebraska to take another look at the cost assumptions used for Flue Gas Desulfurization (FGD) controls. They express that $2,700 per ton is reasonable, and that the cost is likely even lower. 
           
           CDPHE comments that it understands the significance of water shortages in western Nebraska, as the state of Colorado is also in an arid region. They state that all large EGUs in Colorado have installed (or are in the process of installing) FGD controls to reduce SO2 emissions. 
           
           CDPHE goes on to say that the most recent WRAP modeling, which used the CMAQ model, predicts that RMNP is far short of its URP. CDPHE asked that Nebraska reconsider SO2 controls at GGS under the RHR to help Colorado make progress at RMNP.
           
           Nebraska denies this request in their SIP on the basis that WRAP's modeling did not distinguish Nebraska's impact from the other CENRAP states.  Nebraska also makes the argument that a wind rose from RMNP indicates that the wind pattern is rarely from the direction of Nebraska. 
           
           We share Colorado's concerns about the SO2 BART determination for GGS, and as described above, we are proposing to disapprove this deficient BART determination and Nebraska's LTS insofar as the State relied on it to meet the LTS requirements. 

           3. Minnesota 
           Boundary Waters, Voyageurs, Seney, and Isle Royale are referred to as the Northern Midwest Class I areas. As identified in the document, "Reasonable Progress for Class I Areas in the Northern Midwest  -  Factor Analysis," the Lake Michigan Air Directors Consortium (LADCO) identified the following states contributing to Class I area visibility impairment in the LADCO region: Michigan, Minnesota, and Wisconsin, as well as surrounding states, such as the Dakotas, Iowa, Missouri, Illinois, and Indiana. Nebraska does not significantly contribute to visibility impairment at the Minnesota Class I areas according to PSAT modeling. Through RPO consultation, Minnesota determined that no additional emissions reductions from Nebraska sources were needed to meet Class I area visibility improvement goals at this point in time. EPA believes that this satisfies the requirement for consultation between these States. 
                        
           4. Oklahoma 
           As identified in the document titled, "Oklahoma`s Wichita Mountains Wilderness Area Regional Haze Planning," Oklahoma identified Nebraska in its area of influence for NOx.  Nebraska was initially invited to participate in the Oklahoma consultation process. Nebraska states that it provided copies of the draft BART permit packages to the State of Oklahoma while on public notice, which only proposed NOx controls on OPPD and NPPD. Oklahoma did not provide any comment, or request additional controls for the initial planning period. EPA believes that the consultation requirement between these states has been satisfied.

           5. Missouri and Arkansas
           Caney Creek, Upper Buffalo, Hercules Glades, and Mingo are referred to as the central Class I areas. As identified in the document, "Central Class I Areas Consultation Plan," CENRAP identified Nebraska in the area of influence for nitrogen oxides at the central Class I areas.  The central states determined whether a state was a major contributor based on an analysis of four approaches: trajectories, areas of influence, PSAT, and Q/d. If a state was found to be a major contributor in at least 3 of the 4 approaches, the central states concluded it was appropriate to include that state as a major contributor. Nebraska was found to be a contributor based upon the area of influence only, therefore it was excluded as a major contributing state to visibility impairment in Class I areas in Missouri and Arkansas.  EPA believes that Nebraska's consultation requirement with these states was satisfied.  
                  
e. Best Available Retrofit Technology (BART): 40 CFR 51.308(e)
States must submit an implementation plan containing emission limitations representing BART and schedules for compliance with BART for each BART-eligible source that may reasonably be anticipated to cause or contribute to any impairment of visibility in any mandatory Class I Federal area.

            i.         BART eligible sources: 40 CFR 51.308(e)(1)(i)
        States must identify all BART-eligible sources in their SIP. Sources are subject to BART if:
          1. One or more emissions units at the facility belong to one of the twenty-six BART source categories;
          2. The unit did not operate before 7 August 1962 but was in existence on 7 August 1977; and
          3. The unit has the potential to emit 250 tons per year or more of any visibility-impairing pollutant, which Nebraska determined to be SO2, NOx, and PM10.
            
      The BART Guidelines direct states to exercise judgment in deciding whether VOCs and NH3 impair visibility in their Class I area(s). 70 FR 391160. CENRAP performed analyses which demonstrated that anthropogenic emissions of VOC and NH3 do not significantly impair visibility in the CENRAP region. Therefore, Nebraska did not consider ammonia among visibility-impairing pollutants and did not further evaluate NH3 and VOC emissions sources for potential controls under BART or reasonable progress. 
      
      Nebraska used its database to identify potential BART-eligible units and facilities with emission units in one or more of the 26 BART categories. Nebraska then conducted a survey to identify facilities within these source categories with potential emissions of 250 tons per year or more for any visibility-impairing pollutant from any unit that was in existence on August 7, 1977 and began operation after August 7, 1962. More detailed information regarding each facility`s BART-eligible units may be found in Appendix 10.2. EPA proposes to find that Nebraska adequately identified all BART-eligible sources within the State.
                  
           Table 3: Facilities with BART-eligible units in Nebraska
                                Source category
                                   Facility
                                   Location
                  Number of emission units identified by date
            Potential to emit (date-eligible units, tons per year)
                                       
                                       
                                       
                                       
                                     PM10
                                      NOx
                                      SO2
Fossil-fuel fired steam electric plants of more than 250 million BTU per hour heat input
NPPD Gerald Gentlemen Station
Sutherland
                                       2
                                                                          4,460
                                                                         46,200
                                                                         79,200

OPPD Nebraska City
Nebraska City
                                       1
                                                                         43,792
                                                                         19,040
                                                                         45,696

OPPD North Omaha Station
Omaha
                                       2
                                                                            910
                                                                         14,420
                                                                         34,283

NPPD Sheldon Station
Hallam
                                       2
                                                                            908
                                                                          6,020
                                                                         15,100

CW Burdick Generating Station
Grand Island
                                       2
                                                                            997
                                                                          1,923
                                                                         10,304

Lon D. Wright Power Plant
Fremont
                                       2
                                                                             97
                                                                          3,784
                                                                          3,035

Don Henry Power Center
Hastings
                                       1
                                                                             19
                                                                          1,360
                                                                            780

North Denver Station
Hastings
                                       1
                                                                             14
                                                                            426
                                                                            853
Portland cement plants
Ash Grove Cement
Louisville
                                       7
                                                                            528
                                                                          2,373
                                                                          3,182
Chemical process plant; fossil-fuel boilers; hydrofluoric, sulfuric, and nitric acid plant
Beatrice Nitrogen Plant
Beatrice
                                      18
                                                                             48
                                                                            924
                                                                              5
            i. BART subject sources
        Nebraska then screened out some BART-eligible sources from being subject to BART on the basis that they do not cause or contribute to visibility impairment in a Class I area. A contribution threshold of 0.5 deciviews based on the 98th percentile of daily modeled visibility impact over an annual period was used by Nebraska. The BART Guidelines provide States the discretion to set a lower deciview threshold than 0.5 deciviews if the location of a large number of BART-eligible sources within the State and in proximity to a Class I area justifies this approach. The nearest Class I area from any BART-eligible source in Nebraska is over 300 km away, and the State did not have any significant clusters of BART-eligible sources, therefore, the State determined the 0.5 dv threshold was appropriate. 
        
        Nebraska required the owner of each BART-eligible source to conduct dispersion modeling using the CALPUFF model and submit the results to NDEQ. (One exception - NDEQ conducted modeling for the Lon D. Wright Power Plant). The CALPUFF modeling protocol is included in Appendix 10.3.
        
        Nebraska identified eight sources with impacts less than 0.5 deciviews, which were therefore determined not to be BART-subject: 
                  
Table 4: BART-eligible facilities determined not to be subject to BART based on < 0.5 dv impact
Beatrice Nitrogen Plant (Koch Nitrogen)
CW Burdick Generating Station
Ash Grove Cement 
North Denver Station
Don Henry Power Center
NPPD Sheldon Station
Lon D. Wright Power Plant
OPPD North Omaha Station

        Two facilities had impacts greater than 0.5 deciviews, and were therefore determined to be BART-subject: OPPD Nebraska City Station Unit 1 and NPPD Gerald Gentleman Station Units 1 and 2. EPA proposes to find that Nebraska adequately determined which sources in the State were subject to BART.
                  
                 Table 5: BART subject facilities in Nebraska
                                   Facility
                                     Units
                                 Class I area
                      CALPUFF modeled impacts > 0.5 dv
                                       
                                       
                                       
                                     2001
                                     2002
                                     2003
OPPD Nebraska City Station
1
Hercules Glades
                                     0.933
                                     0.556
                                   < 0.05

Wichita Mountains
                                   < 0.05
                                   < 0.05
                                     0.686
NPPD Gerald Gentleman Station
1 & 2
Badlands
                                     2.845
                                     2.828
                                     3.121

Wind Cave 
                                     2.452
                                     2.591
                                     2.127

Wichita Mountains 
                                     1.032
                                     1.206
                                     1.392

Rocky Mountain 
                                     1.136
                                     1.246
                                     1.053

Hercules Glades 
                                     0.826
                                     0.616
                                     0.594

Mingo 
                                     0.615
                                   < 0.05
                                   < 0.05

            ii. PM evaluation
          Nebraska used source-specific CALPUFF modeling to examine the relative contribution of PM, NOx, and SO2 emissions to visibility impairment. 
          
          For Nebraska City Unit 1, direct PM emissions only accounted for 0.32% of impairment on the most impaired year, 2001, at the closest Class I area, Hercules Glades. Nebraska concluded that direct PM emissions from NCS do not significantly contribute to visibility impairment, and therefore, a full five factor BART analysis for PM was not needed. 
          
          For Gerald Gentleman Station, direct PM emissions only accounted for 0.69% of impairment on the most impaired year, 2003, at the closest Class I area, Badlands. Nebraska concluded that direct PM emissions from GGS do not significantly contribute to visibility impairment, and therefore, a full five factor BART analysis for PM was not needed. 
          
          EPA agrees with these conclusions. 
                  
            iii. BART determinations
          The five basic steps of a case-by-case BART analysis are: 
          4.               Identify All Available Retrofit Control Technologies. Control technologies should include pollution prevention, use of add-on controls and combinations of the two. 
          5.               Eliminate Technically Infeasible Options. Technologies demonstrated to be infeasible based on chemical, physical, and engineering principles are excluded from further consideration. 
          6.               Evaluate Control Effectiveness of Remaining Control Technologies. Technically feasible control technologies are ranked in the order of highest expected emission reduction to lowest expected emission reduction.
          7.               Evaluate Impacts and Document Results. Impacts that should be considered for each control technology include: cost of compliance, energy impacts, non-air quality environmental impacts, and the remaining useful life of the unit to be controlled. 
          8.               Evaluate Visibility Impacts. Modeling should be performed on the pre- and post-control emissions to determine the actual impact on visibility and assess the visibility improvement achieved and at what cost. This step does not need to be performed if the most stringent control technology is chosen. 

            1.                  Omaha Public Power District (OPPD)  -  Nebraska City Station (NCS) Unit 1
                 Nebraska and EPA have reached different conclusions as to whether NCS Unit 1 is located at a power plant with a generating capacity in excess of 750 megawatts (MW), or not. If NCS falls within this category of sources, then the BART Guidelines must be followed in determining BART limits and the presumptive limits in the Guidelines would apply. See CAA § 169A (b). In September 2008, Nebraska asked EPA for clarification on whether recently permitted units, such as NCS Unit 2, should be included in the total plant capacity for purposes of applying presumptive BART.  In a response dated November 7, 2008, we indicated it is reasonable to interpret the RHR to mean that if the plant capacity is greater than 750 MW at the time the BART determination is made by the state (i.e., at the time the state places the BART determination on public notice), then the power plant is a facility "having a total generating capacity in excess of 750 [MW]" and any unit at the plant greater than 200 MW is subject to presumptive BART. 
                 
                 The groundbreaking for construction of NCS Unit 2 was September 13, 2005. Nebraska put the NCS Unit 1 BART permit on public notice on December 12, 2008. Unit 2 was operational on May 1, 2009. Nebraska concluded that because NCS Unit 2 was not operational at the time of the BART determination for Unit 1, its capacity did not count towards the 750 MW threshold, and therefore, it was not mandatory for Nebraska to follow 40 CFR 51 Appendix Y in making the BART determination.
                 
                 We concede that there is some question as to whether the NCS Unit 1 is a presumptive unit, requiring use of the BART Guidelines, or not. Regardless, Nebraska did proceed through a basic step-wise analysis of the costs and visibility impacts of available controls. 
                 
                 The BART evaluation for OPPD NCS Unit 1 was conducted by contractors hired by OPPD, and then submitted to Nebraska for review and use. The full analysis may be found in appendix 10.6 of the SIP.
                              
                                   a.                   BART for NOx - NCS Unit 1
                  Step one of a BART analysis is to identify all available retrofit control technologies. Nebraska identified SCONOx, the Pahlman process, selective catalytic reduction (SCR), selective non-catalytic reduction (SNCR), flue gas recirculation (FGR), reducing air preheat temperature (RAP), oxygen trim (OT), low excess air (LEA), over-fire air (OFA), staged combustion air (SCA), and low NOx burners (LNB) as available retrofit controls for NOx at NCS Unit 1. NCS Unit 1 has existing has overfire air, which provides a modest level of NOx control. 
                  
                  Step two is to eliminate technically infeasible options. SNCR was eliminated because the furnace exit temperatures are too high; SCONOx and the Pahlman process were determined to be infeasible as they have not been demonstrated on large coal-fired boilers.
                  
                  Step three is to evaluate the control effectiveness of the technologies that were deemed feasible.
                              
                              
           Table 6: NOx control technology effectiveness, NCS Unit 1
                              Control technology
                           Emission rate (lbs/MMBtu)
                           Potential emissions (tpy)
                               Tons NOx removed
                              Control efficiency
Baseline
                                                                           0.57
                                                                         17,008
                                                                            N/A
                                                                            N/A
LNB/OFA
                                                                           0.23
                                                                          6,827
                                                                         10,181
                                                                            60%
LNB/OFA+SCR
                                                                           0.08
                                                                          2,375
                                                                         14,633
                                                                            86%
                             
                  Step four is to consider the costs, energy impacts, non-air quality environmental impacts, and the remaining useful life of the unit to be controlled. These factors are fully described in the OPPD BART analysis; only the cost of the various options is presented here. 

               Table 7: Cost of NOx control options, NCS Unit 1
                                       
                              Technology Options

                                 LNB/OFA+ SCR
                                    LNB/OFA

Emission Rate (lb/MMBtu)
                                                                           0.08
                                                                           0.23
Emission Reduction (tpy)
                                                                         14,633
                                                                         10,181
Percentage Reduction
                                                                            86%
                                                                            60%
Capital Cost
                                                                  $265,455,000 
                                                                   $21,050,000 
Annualized Capital Cost 
                                                                   $21,300,000 
                                                                    $1,690,000 
Annual Operating Cost
                                                                   $16,910,000 
                                                                            $0 
Total Annualized Cost
                                                                   $38,210,000 
                                                                    $1,690,000 
Total Cost Effectiveness ($/ton)
                                                                        $2,611 
                                                                          $166 
                              
                  Step five is to evaluate the visibility impacts. Results of this analysis are presented in table 8 for the two most impacted Class I areas for NCS Unit 1 (impacts > 0.5 dv). Note that the SO2 control options are also presented in this table; other parts of the SO2 BART analysis are described in the next section. 

           Table 8: Visibility improvement analysis, OPPD NCS Unit 1
                                 Class I area
                              Technology Options
                      Deciview impact, 8[th] high values
                             Improvement (Average)
                                       

                                     2001
                                     2002
                                     2003
                                    Average
                                       
Hercules Glades (Missouri)
Baseline
                                     0.933
                                     0.556
                                     0.473
                                     0.65
                                       

LNB/OFA
                                     0.621
                                     0.358
                                     0.324
                                     0.43
                                     0.22

LNB/OFA +SCR
                                     0.450
                                     0.284
                                     0.252
                                     0.33
                                     0.33

FGD  -  0.15 lbs/MMBtu
                                     0.530
                                     0.355
                                     0.308
                                     0.40
                                     0.25

FGD  -  0.10 lbs/MMBtu
                                     0.493
                                       -
                                       -
                                       -
                                     0.44

LNB/OFA+FGD
                                     0.233
                                     0.159
                                     0.140
                                     0.18
                                     0.47

LNB/OFA+FGD+SCR
                                     0.140
                                     0.084
                                     0.072
                                     0.10
                                     0.55
Wichita Mountains (Oklahoma)
Baseline
                                     0.306
                                     0.381
                                     0.686
                                     0.46
                                       

LNB/OFA
                                     0.233
                                     0.275
                                     0.524
                                     0.34
                                     0.12

LNB/OFA +SCR
                                     0.228
                                     0.258
                                     0.445
                                     0.31
                                     0.15

FGD  -  0.15 lbs/MMBtu
                                     0.153
                                     0.205
                                     0.331
                                     0.23
                                     0.23

FGD  -  0.10 lbs/MMBtu
                                       -
                                       -
                                     0.311
                                       -
                                     0.38

LNB/OFA+FGD
                                     0.069
                                     0.109
                                     0.165
                                     0.11
                                     0.35

LNB/OFA+FGD+SCR
                                     0.053
                                     0.063
                                     0.112
                                     0.08
                                     0.38
2 Class I areas (Cumulative)
Baseline
                                     1.11

                              
      Table 9 combines the average visibility improvement with the costs of control. Again, the two most impacted Class I areas are presented, as well as a cumulative result combining the visibility benefit at both areas. 

                Table 9: Costs for visibility improvement, NCS Unit 1
                                 Class I area
                                Control Options
                       Average dv improvement (2001-03)
                             Total annualized cost
                                     $/dv
Hercules Glades
LNB/OFA
                                     0.22
                                                                     $1,690,000
                                                                     $7,681,818

LNB/OFA+SCR
                                     0.33
                                                                    $38,210,000
                                                                   $115,787,879

FGD  -  0.15 lbs/MMBtu
                                     0.25
                                                                    $34,720,000
                                                                   $138,880,000

FGD  -  0.10 lbs/MMBtu
                                     0.44
                                                                    $34,720,000
                                                                   $78,909,091 

LNB/OFA+FGD
                                     0.47
                                                                   $36,410,000 
                                                                    $77,468,085

LNB/OFA+FGD+SCR
                                     0.55
                                                                    $72,930,000
                                                                   $132,600,000
Wichita Mountains
LNB/OFA
                                     0.12
                                                                     $1,690,000
                                                                    $14,083,333

LNB/OFA +SCR
                                     0.15
                                                                    $38,210,000
                                                                  $254,733,333 

FGD  -  0.15 lbs/MMBtu
                                     0.23
                                                                    $34,720,000
                                                                   $150,956,522

FGD  -  0.10 lbs/MMBtu
                                     0.38
                                                                    $34,720,000
                                                                   $91,368,421 

LNB/OFA+FGD
                                     0.35
                                                                   $36,410,000 
                                                                   $104,028,571

LNB/OFA+FGD+SCR
                                     0.38
                                                                    $72,930,000
                                                                   $191,921,053
2 Class I areas (Cumulative)
LNB/OFA
                                     0.34
                                                                     $1,690,000
                                                                     $4,970,588

LNB/OFA +SCR
                                     0.48
                                                                    $38,210,000
                                                                   $79,604,167 

FGD  -  0.15 lbs/MMBtu
                                     0.48
                                                                    $34,720,000
                                                                    $72,333,333

FGD  -  0.10 lbs/MMBtu
                                     0.82
                                                                    $34,720,000
                                                                   $42,341,463 

LNB/OFA+FGD
                                     0.82
                                                                   $36,410,000 
                                                                    $44,402,439

LNB/OFA+FGD+SCR
                                     0.93
                                                                    $72,930,000
                                                                    $78,419,355
            Nebraska concluded that based on the high incremental cost of $8,203 per ton for the low incremental visibility improvement of 0.11 dv at Hercules Glades, requiring SCR was not warranted. BART for OPPD NCS Unit 1 was determined to be the installation of LNB/OFA with an emission limitation of 0.23 lbs/MMBtu. EPA agrees that the State's determination is reasonable given the relatively insignificant additional visibility improvement associated with SCR for the additional cost. 

                                   b.             BART for SO2 - NCS Unit 1
            Step one is to identify all available retrofit control technologies. Nebraska identified FGD, both throwaway systems (wet and dry FGD) and regenerative processes, as possibilities for SO2 control. Step two is to eliminate technically infeasible options. Coal desulfurization was determined to be infeasible because it has not been demonstrated for low-sulfur coal, as is used at NCS; the Pahlman process and other regenerative processes were determined to be infeasible because they have not been demonstrated on large coal-fired boilers. Therefore, only dry and wet FGD were deemed feasible and subject to further analysis.
            
            We note that Nebraska did not evaluate Dry Sorbent Injection (DSI) as a potential SO2 control for NCS Unit 1. Since DSI can generally achieve the same control efficiency as FGD, we believe that the State has appropriately evaluated the level of controls in its analysis. 
            
            Step three is to evaluate the control effectiveness of the technologies that were deemed feasible. These results are presented in table 10. 
                              
          Table 10: SO2 control technology effectiveness, NCS Unit 1
                              Control Technology
                           Emission rate (lbs/MMBtu)
                           Potential emissions (tpy)
                            Tons SO2 removed (tpy)
                              Control efficiency
Baseline
                                     0.815
                                    24,191
                                      N/A
                                      N/A
Wet FGD
                                     0.15
                                     4,452
                                    19,739
                                      82%
Dry FGD
                                     0.15
                                     4,452
                                    19,739
                                      82%
Dry FGD
                                     0.10
                                     2,969
                                    21,222
                                      88%

            Step four is to consider the costs, energy impacts, non-air quality environmental impacts, and the remaining useful life of the unit to be controlled. These factors are fully described in the OPPD BART analysis; only the cost of the various options is presented here.
            
            Nebraska concluded that dry FGD (spray dryer absorber (SDA)) has lower capital and operating costs than wet FGD and can achieve the same control efficiency; it thus focused its cost analysis on dry FGD.
            
               Table 11: Cost of SO2 control options, NCS Unit 1

                              Technology Options

                                 Dry FGD (SDA)
                                0.15 lbs/MMBtu
                                 Dry FGD (SDA)
                                0.10 lbs/MMBtu
Emission Reduction (tpy)
                                                                         19,739
                                                                         21,222
Percentage Reduction
                                                                            82%
                                                                            88%
Capital Cost
                                                                   $201,660,000
                                                                        unknown
Annualized Capital Cost 
                                                                    $16,180,000
                                                                        unknown
Annual Operating Cost
                                                                    $18,540,000
                                                                        unknown
Total Annualized Cost
                                                                    $34,720,000
                                                                    $34,720,000
Total Cost Effectiveness ($/ton)
                                                                         $1,759
                                                                         $1,636

            Step five is to evaluate the visibility impacts. These are presented in table 8, in the NOx section above. Nebraska concludes that the costs of installing FGD ($34,720,000) are too high for the small amount of visibility improvement (0.44 dv maximum improvement at Hercules Glades), and therefore proposes no SO2 controls as BART for NCS Unit 1. Based on the minimal visibility improvement, EPA agrees that the State's SO2 BART determination for NCS Unit 1 is reasonable.

            2.            Nebraska Public Power District (NPPD)  -  Gerald Gentleman Station (GGS) Units 1 and 2
           Like the BART analysis for OPPD, NPPD hired a contractor to conduct a BART analysis, which was then submitted to NDEQ for review and use. Information presented here is from the March 2008 revised NPPD BART analysis and Nebraska's SIP.

                                   a.             BART for NOx - GGS Units 1 and 2
            Step one is to identify available NOx control technologies. NPPD identified LNB/OFA, SCR, SNCR, SCONOx, and the Palman Process as available technologies for NOx control. In 2006, NPPD installed LNB and OFA for NOx control. Note that this is after the 2001-2003 baseline modeling period used in the CALPUFF modeling. Therefore, LNB/OFA is still examined in this BART analysis. 
            
            Step two is to eliminate technically infeasible options. LNB/OFA and SCR were determined to be technically feasible based on demonstrated performance on many similar units. Nebraska eliminated the following technologies from further consideration:
            
            * SNCR - Infeasible due to high furnace exit temperatures
            * SCONOx - not demonstrated on large coal-fired boilers
            * Pahlman Process - not demonstrated on large coal-fired boilers

            The third step in the BART analysis is to examine the effectiveness of the feasible control technologies. 
                              
       Table 12: NOx control technology effectiveness, GGS Units 1 and 2
                              Control technology
                           Emission rate (lbs/MMBtu)
                           Potential emissions (tpy)
                               Tons NOx removed
                              Control efficiency
Baseline
                                     0.455
                                    30,243
                                      N/A
                                      N/A
LNB/OFA
                                     0.23
                                    15,287
                                    14,956
                                      49%
LNB/OFA+SCR
                                     0.08
                                     5,317
                                    24,926
                                      82%
                             
            The fourth step of the BART analysis is to consider the cost of compliance, energy, non-air quality environmental impacts, and remaining useful life. These factors are described in detail in the BART analysis; only the costs are presented here. 
                     
           Table 13: Cost of NOx control options, GGS Units 1 and 2
                                       
                              Technology Options

                                 LNB/OFA+ SCR
                                    LNB/OFA

Emission Rate (lb/MMBtu)
                                                                           0.08
                                                                           0.23
Emission Reduction (tpy)
                                                                         24,926
                                                                         14,956
Percentage Reduction
                                                                            82%
                                                                            49%
Capital Cost
                                                                   $515,081,000
                                                                    $36,930,000
Annualized Capital Cost 
                                                                    $41,715,000
                                                                     $2,960,000
Annual Operating Cost
                                                                    $14,515,000
                                                                             $0
Annualized Outage Cost 
                                                                     $1,021,000
                                                                             $0
Total Annualized Cost
                                                                    $57,251,000
                                                                     $2,960,000
Total Cost Effectiveness ($/ton)
                                                                         $2,297
                                                                           $198

            The fifth and final step in a BART analysis is to examine the visibility improvements of various control options. Results presented in table 14 are for the six Class I areas which were modeled to be impaired by GGS > 0.5 dv. Both NOx and SO2 controls are presented. Note that although both GGS units have an individual stack, they were modeled as a single stack, so modeling results presented here are for the two units combined.

            Table 14:  Visibility analysis, NPPD GGS Units 1 and 2
                                 Class I area
                          Control technology options
                      Deciview impact, 8[th] high values
                             Improvement (Average)
                                       

                                     2001
                                     2002
                                     2003
                                    Average
                                       
Badlands (South Dakota)
Baseline
                                     2.845
                                     2.828
                                     3.121
                                     2.93
                                       
                                       
FGD (0.15 lbs/MMBtu)
                                     1.836
                                     2.125
                                     2.478
                                     2.15
                                     0.78
                                       
FGD (0.10 lbs/MMBtu)
                                     1.790
                                     2.026
                                     2.443
                                     2.09
                                     0.85
                                       
LNB/OFA
                                     2.224
                                     2.162
                                     2.419
                                     2.27
                                     0.66
                                       
LNB/OFA+SCR
                                     1.732
                                     1.728
                                     1.879
                                     1.78
                                     1.15
                                       
LNB/OFA+FGD
                                     1.107
                                     1.275
                                     1.537
                                     1.31
                                     1.62
                                       
LNB/OFA+FGD+SCR
                                     0.62
                                     0.692
                                     0.757
                                     0.69
                                     2.24
                                       
DSI
                                     1.755
                                     2.147
                                     2.31
                                     2.07
                                     0.86
Wind Cave (South Dakota)
Baseline
                                     2.452
                                     2.591
                                     2.127
                                     2.39
                                       
                                       
FGD
                                     1.61
                                     1.415
                                     1.437
                                     1.49
                                     0.90
                                       
LNB/OFA
                                     1.902
                                     2.051
                                     1.586
                                     1.85
                                     0.54
                                       
LNB/OFA+SCR
                                     1.565
                                     1.659
                                     1.273
                                     1.50
                                     0.89
                                       
LNB/OFA+FGD
                                     1.008
                                     0.856
                                     0.82
                                     0.89
                                     1.50
                                       
LNB/OFA+FGD+SCR
                                     0.586
                                     0.47
                                     0.465
                                     0.51
                                     1.88
Wichita Mountains (Oklahoma)
Baseline
                                     1.032
                                     1.206
                                     1.392
                                     1.21
                                       

FGD
                                     0.67
                                     0.734
                                     0.82
                                     0.74
                                     0.47

LNB/OFA
                                     0.846
                                     0.948
                                     1.086
                                     0.96
                                     0.25

LNB/OFA+SCR
                                     0.681
                                     0.82
                                     1.02
                                     0.84
                                     0.37

LNB/OFA+FGD
                                     0.415
                                     0.423
                                     0.504
                                     0.45
                                     0.76

LNB/OFA+FGD+SCR
                                     0.244
                                     0.245
                                     0.294
                                     0.26
                                     0.95
Rocky Mountain (Colorado)
Baseline
                                     1.136
                                     1.246
                                     1.053
                                     1.15
                                       
                                       
FGD
                                     0.607
                                     0.822
                                     0.646
                                     0.69
                                     0.46
                                       
LNB/OFA
                                     0.927
                                     0.956
                                     0.807
                                     0.90
                                     0.25
                                       
LNB/OFA+SCR
                                     0.788
                                     0.777
                                     0.628
                                     0.73
                                     0.42
                                       
LNB/OFA+FGD
                                     0.38
                                     0.478
                                     0.376
                                     0.41
                                     0.74
                                       
LNB/OFA+FGD+SCR
                                     0.23
                                     0.263
                                     0.205
                                     0.23
                                     0.92
Hercules Glades (Missouri)
Baseline
                                     0.826
                                     0.616
                                     0.594
                                     0.68
                                       
                                       
FGD
                                     0.538
                                     0.327
                                     0.307
                                     0.39
                                     0.29
                                       
LNB/OFA
                                     0.64
                                     0.508
                                     0.46
                                     0.54
                                     0.14
                                       
LNB/OFA+SCR
                                     0.527
                                     0.456
                                     0.40
                                     0.46
                                     0.22
                                       
LNB/OFA+FGD
                                     0.319
                                     0.207
                                     0.201
                                     0.24
                                     0.44
                                       
LNB/OFA+FGD+SCR
                                     0.179
                                     0.122
                                     0.115
                                     0.14
                                     0.54
Mingo (Missouri)
Baseline
                                     0.615
                                     0.432
                                     0.438
                                      0.5
                                       
                                       
FGD
                                     0.299
                                     0.168
                                     0.213
                                     0.23
                                     0.27
                                       
LNB/OFA
                                     0.495
                                     0.365
                                     0.332
                                      0.4
                                     0.10
                                       
LNB/OFA+SCR
                                     0.423
                                     0.308
                                     0.28
                                     0.34
                                     0.16
                                       
LNB/OFA+FGD
                                     0.174
                                     0.11
                                     0.13
                                     0.14
                                     0.36
                                       
LNB/OFA+FGD+SCR
                                     0.108
                                     0.07
                                     0.077
                                     0.09
                                     0.41
6 Class I areas (cumulative)
Baseline
                                     8.86

            The visibility results presented in table 15 are for the closest and most impacted Class I area, Badlands; cumulative results include all 6 Class I areas shown to be impacted by GGS > 0.5 dv.

         Table 15: Costs for visibility improvement, GGS Units 1 and 2

                                Control Options
                       Average dv improvement (2001-03)
                             Total annualized cost
                                     $/dv
Badlands
DSI
                                     0.86
                                                                    $81,958,000
                                                                    $95,300,000

FGD (0.15 lbs/MMBtu)
                                     0.78
                                                                   $108,517,000
                                                                   $139,124,359

FGD (0.10 lbs/MMBtu)
                                     0.85
                                                                   $108,517,000
                                                                  $127,667,059 

LNB/OFA
                                     0.66
                                                                     $2,960,000
                                                                     $4,484,848

LNB/OFA+SCR
                                     1.15
                                                                    $57,251,000
                                                                    $49,783,478

LNB/OFA+FGD
                                     1.62
                                                                   $114,410,000
                                                                    $70,623,457

LNB/OFA+FGD+SCR
                                     2.24
                                                                   $168,701,000
                                                                    $75,312,946
Cumulative, 6 Class I areas
DSI
                                    unknown
                                                                    $81,958,000
                                                                    $47,650,000

FGD
                                     3.17
                                                                   $108,517,000
                                                                    $34,232,492

LNB/OFA
                                     1.94
                                                                     $2,960,000
                                                                     $1,525,773

LNB/OFA+SCR
                                     3.21
                                                                    $57,251,000
                                                                    $17,835,202

LNB/OFA+FGD
                                     5.42
                                                                   $114,410,000
                                                                    $21,108,856

LNB/OFA+FGD+SCR
                                     5.56
                                                                   $168,701,000
                                                                    $30,341,906
            
            Nebraska concluded that based on the relatively low incremental visibility improvement of adding SCR to the LNB/OFA system (0.49 dv, Badlands) for the additional cost ($5,445 incremental cost per ton), requiring SCR as BART was not warranted. BART for OPPD NCS Unit 1 was determined to be the installation of LNB/OFA with an emission limitation of 0.23 lbs/MMBtu, averaged across the two units. EPA agrees that the State's NOx BART determination is reasonable. 
            
                                   b.             BART for SO2 - GGS Units 1 and 2
            Step one is to identify the available control technologies for SO2. Nebraska identified wet and dry FGD, coal desulfurization, the Pahlman process, and other regenerative processes as potential controls. Step two is to eliminate the technically infeasible controls. NPPD eliminated the following controls from further consideration:
            * Coal desulfurization - not demonstrated for low-sulfur PRB coal
            * Pahlman Process - not demonstrated on large coal-fired boilers
            * Other regenerative processes  -  none have been demonstrated on large coal-fired boilers
                              
            In response to comments on the original BART analysis, Nebraska requested that NPPD also evaluate Dry Sorbent Injection (DSI) for SO2 control. Nebraska determined that DSI is a technically feasible control for GGS Units 1 and 2. 
            
            Step three is to examine the effectiveness of the feasible control technologies. These results are presented on table 16.
                              
       Table 16: SO2 control technology effectiveness, GGS Units 1 and 2
                              Control technology
                           Emission rate (lb/MMBtu)
                           Potential emissions (tpy)
                               Tons SO2 removed
                              Control efficiency
Baseline
                                     0.749
                                    49,785
                                      N/A
                                      N/A
Wet FGD
                                     0.15
                                     9,970
                                    39,815
                                      80%
Dry FGD
                                     0.15
                                     9,970
                                    39,815
                                      80%
DSI
                                     0.15
                                     9,970
                                    39,815
                                      80%
FGD
                                     0.10
                                     6,647
                                    43,138
                                      87%

            Step four is to consider the cost of compliance, energy, non-air quality environmental impacts, and remaining useful life. These factors are described in detail in the BART analysis; the costs are presented here, as well as a significant non-air quality environmental issue (water availability) raised by Nebraska.
                              
           Table 17: Cost of SO2 control options, GGS Units 1 and 2
                                       
                              Technology Options

                                    Dry FGD
                                    Wet FGD
                                      DSI
                                      FGD
Emission Rate (lb/MMBtu)
                                                                           0.15
                                                                           0.15
                                                                           0.15
                                                                           0.10
Emission Reduction (tpy)
                                                                         39,815
                                                                         39,815
                                                                         39,815
                                                                         43,138
Percentage Reduction
                                                                            80%
                                                                            80%
                                                                            80%
                                                                            87%
Capital Cost
                                                                  $981,592,000 
                                                                 $1,029,819,000
                                                                   $208,330,000
                                                                        unknown
Annualized Capital Cost 
                                                                    $80,013,000
                                                                    $83,965,000
                                                                    $17,500,000
                                                                        unknown
Annual Operating Cost
                                                                    $27,806,000
                                                                    $24,485,000
                                                                    $64,458,000
                                                                        unknown
Annualized Outage Cost 
                                                                       $698,000
                                                                             $0
                                                                             $0
                                                                        unknown
Total Annualized Cost
                                                                   $108,517,000
                                                                   $108,450,000
                                                                    $81,958,000
                                                                   $123,933,694
Total Cost Effectiveness ($/ton)
                                                                         $2,726
                                                                         $2,724
                                                                         $2,058
                                                                         $2,873

            Costs per ton for wet and dry FGD at a rate of 0.15 lbs/MMBtu were nearly identical, and Nebraska concluded that these costs were reasonable on a cost per ton basis ($2,726/ton). Nebraska found DSI to be more cost effective, at $2,058 per ton. 
            
            Nebraska raises water use of wet and dry FGD as a significant non-air environmental impact. In its SIP, Nebraska presents a description of the over-appropriation of water resources in the western part of the State, where GGS is located. The State described that over-appropriation means that any new use of water requires an offset in water consumption in the same area.  To do this, NPPD would have to purchase the ground water rights from surrounding landowners.
            
            Nebraska did not include the cost of obtaining these water rights in the original BART analysis costs; however, in the narrative portion of the SIP, Nebraska describes both the costs of obtaining water, and the loss of agricultural revenue due to taking land out of agricultural production:
            
                  "For purposes of the cost effectiveness analysis, only the loss of revenue (2007 figures) was added to the annualized costs, which increased the total annualized costs to $123,933,694. Approximately 5.7% of the costs are associated with the loss of crop value. Overall, the impact as a result due to water-related issues increased the annualized costs from $108,450,000 [to operate FGD] to $123,933,694, a 14.3% increase. The NDEQ concluded this is a significant economic impact." 
                              
            If the costs to obtain water rights were added into the BART analysis, the FGD costs would increase to $117,776,000. (EPA is not including the loss of crop value in its analysis). As seen in table 18, adding in the costs of water rights only increases the cost of control by $234 per ton. This brings the cost per ton to $2,958, which EPA believes is still a reasonable cost of control. 
                              
   Table 18: Cost of SO2 control  and visibility benefit, GGS Units 1 and 2
                                       
                              Technology Options

                       Wet FGD (original BART analysis)
                   Wet FGD (revised with water offset costs)
                       Wet FGD (with water offset costs)
                                      DSI
Emission Rate (lb/MMBtu)
                                                                           0.15
                                                                           0.15
                                                                           0.10
                                                                           0.15
Total Annualized Cost
                                                                   $108,450,000
                                                                   $117,776,000
                                                                   $123,933,694
                                                                    $81,958,000
Total Cost Effectiveness ($/ton)
                                                                         $2,724
                                                                         $2,958
                                                                         $2,873
                                                                         $2,058
Average visibility improvement (Badlands)
                                                                           0.78
                                                                           0.78
                                                                           0.85
                                                                           0.86
Average visibility improvement (Cumulative)
                                                                           3.17
                                                                           3.17
                                                                        unknown
                                                                        unknown
$/dv (Badlands)
                                                                   $139,124,359
                                                                   $150,994,872
                                                                   $145,804,346
                                                                    $95,300,000
$/dv (Cumulative)
                                                                    $34,232,492
                                                                    $37,153,312
                                                                        unknown
                                                                        unknown

            Step five is to examine the visibility improvements of various control options. Results are presented in table 14 and 15, above. Significant visibility improvement is seen from all of the control options, ranging from 0.78 dv average improvement at Badlands from installation of FGD, to 1.62 average dv improvement at Badlands from installation of LNB/OFA plus FGD.  If considered on a cumulative basis, GGS has a baseline impact on 6 Class I areas of 8.86 dv. Installation of FGD would offer an average of 3.17 dv cumulative improvement, and in combination with LNB/OFA, 5.42 dv cumulative improvement. 
            
            In the SIP, Nebraska says that it used a $40,000,000/yr/dv threshold for determining what would be considered reasonable investment for visibility improvement. They concluded that the costs of FGD control were reasonable on a cost per ton basis, but not on a dollars per deciview basis. Furthermore, Nebraska sees the water consumption of FGD controls as significant, and concludes that because of this unique situation, FGD controls are unreasonable for GGS Units 1 and 2. 
            
            EPA disagrees with this conclusion. Using Nebraska's costs, we agree that the cost per ton for FGD control is reasonable, and also see the visibility improvement, both at Badlands and on a cumulative basis, as significant.  
            
            We believe that Nebraska also inappropriately ruled out DSI. Costs for the control are reasonable at $2,058 per ton and visibility improvement at Badlands is significant at 0.86 dv.  If considered cumulatively, visibility improvement would be even more significant, although as mentioned previously, Nebraska did not provide that analysis in their SIP.  Furthermore, DSI does not present the same water consumption issues as FGD.
            
            Finally, as described in detail in appendix A, B, and C of this TSD, we believe that Nebraska's costs of FGD control are overestimated. EPA conducted an independent analysis of the cost information presented by Nebraska in its BART analysis for dry scrubbers. Although we did not review the BART cost analysis for wet scrubbers, many of the same issues likely apply. Note that our analysis of the cost elements was not comprehensive, but only addresses what we see as some of the most significant errors and deviations from EPA's Cost Control Manual.
            
            Categories which we found significant overestimations include:
            * Engineering Procurement and Construction
            * Bond Fees
            * Escalation
            * Contingency
            * Allowance for Funds Used During Construction
            * Capital Recovery Factor
            * Operation and Maintenance

            We also found that Nebraska incorrectly calculated the SO2 emission rates. On page 15 of its BART analysis, NPPD calculates its SO2 emission baseline based on applying a 24 hour maximum emission rate of 0.749 lbs/MMBtu (2001-2003) to a maximum heat input of 15,175.5 MMBtu/hr, based on a 100% capacity factor. This results in an emissions baseline of 49,785 tons/yr. We believe this calculation does not appropriately represent GGS's SO2 emission baseline, and is in fact too high. The Regional Haze Rule provides the following regarding the calculation of the BART emissions baseline:
            
                  "The baseline emissions rate should represent a realistic depiction of anticipated annual emissions for the source.  In general, for the existing sources subject to BART, you will estimate the anticipated annual emissions based upon actual emissions from a baseline period. When you project that future operating parameters (e.g., limited hours of operation or capacity utilization, type of fuel, raw materials or product mix or type) will differ from past practice, and if this projection has a deciding effect in the BART determination, then you must make these parameters or assumptions into enforceable limitations.  In the absence of enforceable limitations, you calculate baseline emissions based upon continuation of past practice."
                  
            We see no indications that NPPD's future operating practices are projected to deviate from the past. GGS states on page 2 of its BART analysis that it used a baseline period of 2001-2003, which was the baseline emission rate period for BART modeling in Nebraska.  We have downloaded emissions data for GGS from our Clean Air Markets web siteand have calculated the average total station SO2 emissions for GGS Units 1 and 2 to be 31,513 tons/yr for the three year period of 2001-2003.  We note that based on GGS's stated capacity of Units 1 and 2 (665 and 700 MW, respectively), we calculate capacity factors for Units 1 and 2 to range from 89% to 94% and 77% to 85%, respectively, from 2001-2003. Our analysis assumes this historic usage is not significantly altered in the future.  A summary of this data appears in appendix B to the TSD.
            
            Using the same emissions data from the three year averaging period of 2001-2003, we have calculated the three year average annual SO2 emissions for units 1 and 2 of the GGS to be 0.565 lbs/MMBtu.  Reducing this to a controlled SO2 emissions level of 0.15 lbs/MMBtu results in a scrubber efficiency of approximately 73.5%.  Applying this level of control to our adjusted GGS SO2 emission baseline of 31,513 tons/yr would reduce it to 8,366 tons/yr, resulting in a reduction of 23,147 tons of SO2 annually. Applying the same approximate 80% level of reduction GGS assumes to our adjusted GGS SO2 emission baseline of 31,513 tons/yr would reduce it to 6,311 tons/yr, resulting in a reduction of 25,202 tons of SO2 annually.
            
            However, dry scrubbers are capable of much greater control efficiencies than the 80% level that Nebraska assumes. Therefore, for the purpose of calculating the cost effectiveness of dry scrubbers at the GGS, we have assumed an SO2 emission limit of 0.06 lbs/MMBtu, which results in a scrubber efficiency of approximately 89.4%.  Applying this level of control to our adjusted GGS baseline of 31,513 tons/yr would reduce it to 3,347 tons/yr, resulting in a reduction of 28,166 tons of SO2 annually.
            
            Table 19 summarizes EPA's adjustments to the NPPD cost estimates for dry FGD control. 
                              
               Table 19: Range of GGS Dry Scrubber Cost Effectiveness

                                    Dry FGD
                         (original NPPD BART analysis)
                                    Dry FGD
                               EPA's estimate
SO2 Baseline
                                    49,785
                                    31,513
Uncontrolled Emission Level (lbs/MMBtu)
                                     0.749
                                     0.565
Controlled Emission Rate (lbs/MMBtu)
                                     0.15
                                     0.15
                                     0.11
                                     0.06
Percent Reduction
                                      80%
                                     73.5%
                                      80%
                                     89.4%
SO2 Emission Reduction (tons)
                                    39,815
                                    23,147
                                    25,202
                                    28,166
Total Annualized Cost
                                 $108,535,690
                                  $53,469,570
                                  $54,335,512
                                  $55,543,352
Total Cost Effectiveness ($/ton)
                                    $2,726
                                    $2,310
                                    $2,156
                                    $1,972
            
            In summary, we believe that Nebraska overestimated the costs of FGD controls; did not do a full evaluation of the potential visibility benefits from levels of control that FGD is capable of achieving; and improperly rejected DSI. We believe that the cost per ton of SO2 controls ranging from $1,972 (our analysis) to $2,958 (Nebraska's analysis, plus water) is reasonable; and that the visibility benefits, whether considered just at Badlands or cumulatively, are significant. Therefore, EPA proposes to disapprove Nebraska's BART determination for SO2 at Gerald Gentleman Station. 

            i.             BART summary and enforceability: 40 CFR 51.308(e)(1)(iv) - (v)
            Table 20 is a summary of the BART determinations made by Nebraska for BART-subject units. 

                   Table 20: Summary of BART determinations
                                Facility, Units
                                   Pollutant
                     BART controls determined by Nebraska
                        EPA's proposed determination
OPPD Nebraska City Station, Unit 1
                                      NOx
Install LNB with OFA, meet level of 0.23 lbs/MMBtu.
Approval

                                      SO2
No additional controls.
Approval
NPPD Gerald Gentleman Station, Units 1 and 2
                                      NOx
Install LNB with OFA. Meet level of 0.23 lbs/MMBtu. 
Approval

                                      SO2
No additional controls. 
Disapproval
            
            Each source subject to BART must install and operate BART as expeditiously as practicable, but in no event later than 5 years after approval of the SIP revision; and include monitoring, recordkeeping and reporting requirements to ensure the BART limits are enforceable.
            
            Nebraska chose to incorporate BART requirements into PSD permits issued pursuant to Title 129 of the Nebraska Air Quality Regulations, Chapter 19. These limits will be incorporated into the facility's Title V permits after SIP approval. The permits require that the limits be met within 5 years of approval of Nebraska's regional haze SIP. The limits must be met on a 30-day rolling average basis at all times, including periods of startup, shutdown, and malfunction. The permits require the use of a NOx continuous emission monitoring system (CEMS) on each unit to demonstrate compliance with the BART NOx limits. Each CEMS is required to be operated and certified in accordance with 40 CFR Part 75. Recordkeeping and reporting is also required to be in accordance with 40 CFR Part 75. We have reviewed these requirements and propose to find them adequate as they relate to the BART limits we are proposing to approve.

f.             Monitoring strategy: 40 CFR  51.308(d)(4) 
            Because it does not host a Class I area, Nebraska is not required to develop a monitoring strategy for measuring, characterizing, and reporting regional haze impairment that is representative of Class I areas within the State. However, the State is required to establish procedures by which monitoring data and other information is used to determine the contribution of emissions from within the State to regional haze impairment at Class I areas outside of the State.  
            
            Compliance with this requirement is met by participation in the Interagency Monitoring of Protected Visual Environments (IMPROVE) network. Nebraska installed one IMPROVE protocol sampler at Nebraska National Forest County near Halsey, NE in the central part of the State, and another at Crescent Lake National Wild Life Refuge in the panhandle of the state. A third IMPROVE Protocol sampler in Nebraska is operated independently in Thurston County, by the Omaha Tribe of Nebraska, although EPA notes that this monitor is not currently operating.
            
            EPA believes the State's commitment to utilize data from these sites, or any other EPA- approved monitoring network location, to characterize and model conditions within the state and to compare visibility conditions in the state to visibility impairment at Class I areas hosted by other states, and proposes that Nebraska has satisfied the monitoring requirements of 40 CFR 51.308(d)(4).  

g.             Emissions inventory: 40 CFR 51.308 (d)(4)(v)
            States are required to develop a statewide inventory of emissions of pollutants that are reasonably anticipated to cause or contribute to visibility impairment in any Class I area. The inventory must include emissions for a baseline year, emissions for the most recent year with available data, and future projected emissions. 
            
            As mentioned previously, Nebraska worked with CENRAP and its contractors to develop statewide emission inventories for 2002 and 2018. Detailed methodologies are documented in appendices 8.3 and 9.1. The 2018 emissions inventory was developed by projecting 2002 emissions and applying reductions expected from federal and state regulations affecting the emissions of the visibility-impairing pollutants NOx, PM, SO2, and VOCs. The 2002 emissions were grown to year 2018 primarily using the Economic Growth Analysis System (EGAS6), MOBILE 6.2 vehicle emission modeling software, and the Integrated Planning Model (IPM) version 2.93 for EGUs. The 2018 emissions for EGUs were based on simulations of the IPM that took into the account the effects of CAIR on emissions. 
            
            At the time modeling was conducted, BART decisions had not been made by many states, including Nebraska. Presumptive levels of BART control were assumed in projections of 2018 emissions. The 2018 inventory was then updated to account for Nebraska's BART decisions.  
            
           Table 21: 2002 Nebraska Emissions Summary (tons per year)

                                     VOC 
                                     NOx 
                                     SO2 
                                     PM10 
                                    PM2.5 
Point 
                                                                          7,274
                                                                         58,619
                                                                         73,487
                                                                         13,105
                                                                          4,638
Area 
                                                                         66,769
                                                                         15,023
                                                                          7,748
                                                                        447,703
                                                                         83,852
On-Road
                                                                         43,113
                                                                         61,850
                                                                          1,822
                                                                          1,277
                                                                            930
Non-Road
                                                                         24,882
                                                                        119,568
                                                                         11,011
                                                                          7,491
                                                                          6,785
Fire 
                                                                          3,204
                                                                            679
                                                                            268
                                                                          5,057
                                                                          3,956
Biogenic 
                                                                        533,705
                                                                         39,446
                                                                              0
                                                                              0
                                                                              0
Total 
                                                                        678,947
                                                                        295,185
                                                                         94,336
                                                                        474,633
                                                                        100,161

              Table 22: 2018 Nebraska Projected Emissions Summary
                                (tons per year)

                                     VOC 
                                     NOx 
                                     SO2 
                                     PM10 
                                    PM2.5 
Point 
                                                                        13,344 
                                                                        56,190 
                                                                        82,193 
                                                                        18,654 
                                                                         8,596 
Area 
                                                                        78,417 
                                                                        17,737 
                                                                         9,793 
                                                                       303,578 
                                                                        56,193 
On-Road
                                                                        18,862 
                                                                        19,702 
                                                                           236 
                                                                           432 
                                                                           432 
Non-Road
                                                                        14,611 
                                                                        50,972 
                                                                           226 
                                                                         3,269 
                                                                         2,974 
Fire 
                                                                         3,204 
                                                                           679 
                                                                           268 
                                                                         5,057 
                                                                         3,956 
Biogenic 
                                                                       533,705 
                                                                        39,446 
                                                                             0 
                                                                             0 
                                                                             0 
Total 
                                                                       660,868 
                                                                       185,040 
                                                                        92,716 
                                                                       335,012 
                                                                        76,610 
      
            The EPA believes the 2002 and 2018 statewide emissions inventories and the State's method for developing the 2018 emissions inventory for Nebraska meets the requirements of the RHR. Nebraska has also committed to update inventory periodically, therefore, we propose that Nebraska has met the requirements of 40 CFR § 51.308(d)(4)(v).
            
h.             Federal Land Manager (FLM) consultation: 40 CFR 51.308(i)
            By November 29, 1999, Nebraska was required to identify in writing to the FLMs the title of the official to which the FLM of any Class I area can submit recommendations. Nebraska has satisfied this requirement by identifying the Air Division Administrator at the Nebraska Department of Environmental Quality as this official. 
            
            States are required to provide the FLMs an opportunity for consultation, in person and at least 60 days prior to holding any public hearing on the SIP (or its revision). Consultations should include the opportunity for the FLMs to discuss their assessment of impairment of visibility in any Class I area; and recommendations on the development of the RPG and on the development and implementation of strategies to address visibility impairment. 

            Nebraska provided several opportunities for the FLMs to comment on Nebraska's regional haze plan. Nebraska sent the draft BART permits for NPPD and OPPD to the FLMs in mid-2008, and again prior to public notice. Nebraska provided the FLMs with a draft of the Nebraska regional haze SIP on November 16, 2010, and received formal comments from the National Park Service (NPS), the US Fish and Wildlife Service (USFWS), and the US Forest Service (USFS) in January 2011.
            
            In developing any SIP (or plan revision), States must include a description of how it addressed any comments provided by the FLMs. The FLM comments and Nebraska's responses are provided in appendix 3 of the SIP, and are summarized below. 
            
            The FLMs believe that Nebraska did not met the requirement to include the measures necessary to achieve the reasonable progress goals established by States having mandatory Class I Federal areas in its draft SIP. They note that, "the goals established by South Dakota for Badlands and Wind Cave National Parks, by Colorado for Rocky Mountain National Park, by Oklahoma for Wichita Mountains, and by Missouri for Mingo Wildlife Refuge and Hercules Glade Wilderness Area, as well as other Class I areas, assume that Nebraska will require presumptive BART controls for the Gerald Gentleman and Nebraska City power plants as modeled by WRAP and CENRAP. Nebraska proposes not to require controls of SO2 for any of the BART units. Nebraska's long term strategy does not include the controls required to meet its contribution to the reasonable progress goals established by its neighboring states through the RPO process." 
            
            The FLMs also have expressed concerns with Nebraska's BART analyses at Nebraska City Station (NCS) Unit 1 and Gerald Gentleman Station (GGS) Units 1 and 2. For NCS, the FLMs ask Nebraska to seriously consider all feasible SO2 control options, including DSI, and NOx controls, including SNCR, as part of the five factor analysis. They state that $1,636 per ton for SDA with a fabric filter is reasonable and should be considered as BART for Unit 1. They disagree with ruling out SCR for NOx control, as it is cost effective. The FLMs also questioned whether the cost estimates were developed consistent with the EPA Control Cost Manual. They also ask Nebraska to consider upgrade of the existing PM control as a BART alternative. 
            
            The FLMs go on to say that the BART determination for GGS is not acceptable as written, disagreeing with Nebraska's BART determination of no SO2 controls for Gerald Gentleman. They point out that the visibility impact of these units is significant at more than just the closest Class I area (Badlands); they also take issue with several aspects of the cost estimation, such as escalation, contingencies, allowance for funds during construction, overestimation of direct annual costs. 
            
            The FLMs did an analysis of what they believe a more appropriate cost estimation would be, and found that costs for a dry FGD system should be $87,101,902 in annualized cost, or $2,155 per ton. This is 20% lower than NPPD's estimates. For a wet FGD system, annualized costs were estimated to be $85,696,911, or a cost of $2,073/ton. This is 21% lower than NPPD's estimates.
            
            Regarding Nebraska's argument about the significance of water availability, the United States Fish and Wildlife Service Air Branch asked the USFWS's Nebraska Field Office to review Nebraska's Draft Regional Haze SIP and comment on the merits of the arguments on water and endangered species protection. In a memo dated December 22, 2010, the USFWS Nebraska Field Office responded that, "the arguments given by NDEQ have some merit. However, the Platte River Recovery Implementation Program (PRRIP) inherently provides options to offset consumptive use that results in depletions to the river and jeopardizes endangered species. Additionally, it appears much of the information provided in Nebraska's plan represents a worst-case scenario when describing offsets to water used by the NPPD. While not inaccurate, the information tends to overstate implications of any new water use by NPPD....in summary, there is no question any new depletions to central Platte River flows would require offsets. Because of this, there is the possibility that accelerating actions to achieve air quality improvements would weaken Nebraska's ability to meet its PRRIP obligations to improve Platte River flows on schedule. But we do not believe that it automatically follows that air quality improvements cannot be pursued because Nebraska simply could not do both."
            
            Finally, regional haze SIPs must provide procedures for continuing consultation between the State and FLMs on the implementation of 51.308, including development and review of SIP revisions and 5-year progress reports, and on the implementation of other programs having the potential to contribute to impairment of visibility in Class I areas. Nebraska has committed to continuing to coordinate and consult with the FLMs during the development of future progress reports and plan revisions, as well as during the implementation of programs having the potential to contribute to visibility impairment in Class I areas. 
            
            We propose that Nebraska has satisfied the FLM consultation requirements of 40 CFR 51.308 (i).
            
i.             Periodic SIP revisions and five year progress report: 40 CFR 51.308 (f)-(h)
            Nebraska acknowledged the requirement to submit periodic progress reports and regional haze SIP revisions, with the first report due by July 31, 2018, and revisions due every ten years thereafter. Nebraska committed to meeting this requirement.
            
            Nebraska also acknowledged the requirement to submit periodic reports evaluating progress towards the reasonable progress goals established for each mandatory Class I area. Nebraska committed to complete the first five-year progress report by December 31, 2016. The report will evaluate the progress made towards the reasonable progress goal for each mandatory Class I area located outside Nebraska, which may be affected by emissions from within Nebraska. Using the findings of this first report, Nebraska committed to determining whether the adequacy of the plan is sufficient and taking appropriate action to revise the SIP as needed.
            
            We propose to find that Nebraska has satisfied the requirements to commit to periodic SIP revisions and progress reports as required by 40 CFR 51.308(f)-(h).