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IN THE MATTER OF APERMIT APPLICATION (AP-6047) FROMBASIN ELECTRIC POWER COOPERATIVE FOR A BEST AVAILABLE RETROFIT TECHNOLOGY (BART) PERMIT FORTHE LARAMIE RIVER STATION DECISION 

### I. Introduction: The Air Quality Division received a BART permit application from Basin Electric Power Cooperative (Basin Electric) for the three coal-fired boilers (Units 1 through 3) that operate at their Laramie River Station in Platte County, Wyoming. Regulations governing the BART program have been established by the U.S. EPA in 40 CFR Part 51

- Appendix Y. As stated in the regulations, a source is eligible for BART ifit belongs within a particular group ofstationary source categories, was not in operation prior to August 7, 1962, was in existence on August 7, 1977, and has the potential to emit 250 tons per year (tpy) or more ofany visibility impairing air pollutant. Fossil fuel boilers with more than 250 million Btu (MMBtu) pefJhour heat input are listed as an,eligible source type. Units 1 through 3 atthe Laramie River Station have heat inputs of6,420-6,600 MMBtu per hour and were in existence on August 7, 1977,. Potential emissions from each boiler for two visibility impairing air pollutants, nitrogen oxides 

### (NOx) and sulfur dioxide (S02), exceed 250 tpy and therefore theunits are eligible for BART. The Division conducted an analysis of the BART permit application for the Laramie River Station and on June 3, 2009, published in the Platte County Record Times a public notice and notice ofpublic hearing ofthe proposed,intent to issue BART determinations. Copies ofthe BART application andthe Division's analysis were placed in the Platte County Clerk's office in ,Wheatland, Wyoming in accordance with regulations. A 65-day public notice period ran from June 3;2009 toAugust 6, 2009, and apublichearing was held onAugust6,2009,atlp.m; atthePlatte County Library, located at904 9th Streetin Wheatland. The Division received numerous comment letters on the proposed permit during the public comment period: 1) a letter dated July 21, 2009 from the USDA Forest Service; 2) a letter dated August 3,2009 from EPA Region 8; 3) a letter dated August 4,2009 from PacifiCorp; 4) a letter dated August 4, 2009 from the National Park Service;'5) a letter dated August 4,2009 from the Powder River Basin Resource Council, et al.; 6) a letter dated August 5, 2009 from the Powder River Basin Resource Council; 7) a letterreceived July 20, 2009 from Joanna Taylor; 8) a letter dated July 16, 2009 from Andrew H. Salter;' 9) a letter received July 20, 2009 from Evelyn and Marvin Griffin; 10) a letter received July 23, 2009 from Mimi McMillen; 11) a letter received July 24, 2009 from William M. Anderson; 12) a letter received July 24, 2009 from Rebekah Smith; 13) a letter dated July 24, 2009 from Mike Shonsey; 14) a letter dated July 24,2009 from Susie Mohrmann; 15) a letter dated July 28, 2009 from Janice H. Harris; 16) a letter dated July 28,2009 from M. Christensen; 17) a letter dated July 27, 2009 from ClintMorrison; 18) a letter dated August 3, 2009 from Ann Fuller; 19) a letter dated August 3,2009 from Mary Fenton; 20) 725 ullsigned letters received under a signed cover letter dated July 28, 2009 from Brad Mohrmann, Sierra Club Associate Regional Representative; and 21) 89 signatures received under a signed cover letter dated July 24, 2009 from Brad Mohrmann, Sierra Club Associate Regional Representative. The Division also received a letterfrom Basin Electric dated August 5,2009. Due to the number ofpublic comments with similar concerns, the Division grouped individual comments and developed summary comments and responses. Comments from the EPA, Forest Service, National Park Service, Powder River Basin Resource Council, et aI., and PacifiCorp are addressed individually. The comments and responses are presented on the following pages. The

AQD LRS BART 000475•••• _0 ••• _,-",

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BasinElectric Laramie River Station Decision Document, BARTPermitApplication, AP-6047 Page 2 of23 Division also received positive comments supporting this project. The Division appreciates these comments butthey are not included inthis document as no response is required. The Division received numerous comments that were descriptive ofenvironmental impacts other than the impacts from BART-eligible sources in Wyoming on Class I area visibility. The Division's responses are limitedto the comments that dealtwith the State's BART analyses. The Division is also preparing a revised Wyoming,State Implementation Plan (SIP) for Regional Haze, and has solicited comments on that SIP. Some comments have been received which were submitted as comments on the Regional Haze SIP, butwere principally directed atthe Division's BART analyses. These comments will be addressed bythe Division as it preparesthe response to comments onthe Regional Haze SIP. II. 'Analysis ofComments from the USDA Forest Service: 

### ll.l NO!.. Step 5: Visibility Improvement Determination (Class I areas modeled)

- .The Forest Service commentedthat all.class I areas within 300 km ofa given source should be modeled and the cost ofeach BART alternative divided by the sum ofthe deciview (dv) improvement at all impacted Class I areas. Ifmodeling exists for Class I areas that yield impacts above 0.5 dvjust beyond 300 km, those results should ,be considered also. Savage Run Wilderness Area should also be modeled and considered. ' ,

- Response,.,. Only those Class I areas most likely tobejmpactedbysources subjectto BAR Tata_ given facility were modeled, as determined by source/Class I area locations, distances to each Class I area, and professional judgment considering meteorological and terrain factors. The Division recognizes that more distant Class I areas may yield modeled impacts of some magnitude, but the Division is also satisfied that Class I areas at a greater distance and in directions ofless frequent plume transport would not yield modeled impacts greater than those yielded by the Class I areas chosen for BART modeling. The modeling results for the Class I areas chosen for analysis allowed the Division to make an informed decision on the effect on visibility from the various BART control options. Additionally, EPA's Appendix Y BART guidance does not include any requirements for modeling distance. EPA's Appendix Y BART guidance does mention that "dollars per deciview" ($/dv) is a metric that could be used to evaluate the cost ofBART compliance" but,by no means identifies $/dv as an essential or required metric. The Division considered capital cost, annual cost, cost effectiveness, and incremental cost effeCtiveness in the cost evaluation ofeach proposed BART control option. The Division chose not to use a hybrid metric such as $/dv primarily because of the lack of historical precedent regarding reasonable/acceptable levels for such a metric. Additionally, the use ofa hybrid cost metric such as $/deciview can introduce uncertainty as to how the value was calculated. The.value of"/deciview" could,be based on the highest modeled value in a given area orthe 98lh percentilemodeled value. It could be based onthe 98lh percentile value for anyone modeled year or it could be an average for multiple years. It could even be based on an average modeled value across an entire Class I area or the sum ofdeciview changes across multiple areas. The Division has found that $/dv values are often presented without explanation ofthe basis for the calculation. To avoid these confounding factors, the Division' choseto evaluate and presentthe cost analyses and visibility analyses separately.

AQD LRS BART 000476- _ ....!

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BasinElectricLaramie River Station DecisionDocument, BARTPermitApplication, AP-6047 Page 3 of23 EPA's Regional Haze Rule affects sources that may cause or contribute to visibility impairment at any mandatory, federal Class I Area. Because Savage Run is a state-designated Class I area, the Division was notrequired to include it inthe BART modeling. Additionally, the Division did not include Savage Run in any ofits analyses for the State's Regional Haze Visibility SIP. For BART, the Division did model the impacts at several mandatory Class I areas that are located in the same general plume transport direction downwind of Savage Run, including Mt. Zirkel Wilderness, Rawah Wilderness, and Rocky Mountain National Park.
.Based on the modeling results for these Class 1 Areas in the proximity ofSavage Run, the Division anticipates similar improvements in visibility from the analyzed emission reductions. II.2 NO! Step 5: Visibility Improvement Determination (significant impact)

- The Forest Service commented that it is incorrectto dismiss acontrol strategy on the basis thatthe modeled visibility improvement is notpercepti1?le or significant.
. Response

- The Division used 0.5 dv as the threshold level to exempt a source from BART or to deem modeled impacts as insignificant. EPA's Regional 

### Haze Regulations and Guidelinesfor BestAvailable Retrofit Technology (BART) Determinations (Appendix 

### Y to 40 CFR part 51), suggest that 0.5 dv can represent the level at which a source "contributes" to visibility impairment. This is also consistent with the rules which are being applied by most states in the Western Regional**Ai~** Partnership (WRAP) region. II.3 NO:!....Controls: SCR

- The Forest Service commented that significant, cumulative visibility improvements modeledfor SCRinstallations aUhdim Bridger and Naughton plantsinciicatetha.t SCR should be BART for all units at those two plants. The Forest Service questions why DEQ chose SCRas BART only for Naughton Unit 3 when SCRcosts for otherNaughton units and all Jim Bridgerunits are similar. Also, environmental degradation from the operation ofSCR should not be a factor in the BART determinations 'and energy impacts from SCR should not be a factor because they have already been considered iq. the cost analysis. Response

- The costs for SCR controls, as described in the Division's BART analyses, were deemed by the Division to be reasonable for all units attheJim Bridger and Naughton plants, but the Division's BART determinations forthe two plants were based on consideration ofall five statutory BART factors, as reqliired by EPA's Appendix 

### Y BART guidance. PacifiCorp proposed a BART limit for NOx emissions from Naughton Unit 3 of 0.371b/MMBtu, which would be achieved by tuning the existing LNB/OFA system. For Naughton Units 1 and 2, PacifiCorp proposed a BART limit for NOx of 0.26 Ib/MMBtu for each unit using new LNB/OFA. Visibility modeling showed that the NOxemission level proposed by PacifiCorp for Naughton Unit 3 provided less in terms of modeled visibility reductions from baseline as compared to otherunits atthetwo plants. For example, Naughton Units 1 and 2 showed a 72% to 73% reduction in the number of days with predicted impacts of 0.5 dv or more at the nearest Class'l area (Bridger Wilderness) for LNB/OFA as compared to baseline. The reduction for Naughton Unit 3 for LNB/OF A vs. baseline was only 31%. Appendix A includes graphs ofthe modeled results at the Class I area that yielded the highest modeled impacts for the Jim Bridger and Naughton plants (Bridger Wilderness) and the Class I area that yielded the highest modeled impacts for the Wyodak, Dave Johnston, and Laramie River Station plants (Wind Cave National Park), As shown in the graphs, the LNB/OFA option reduces the 98th percentile result to less than 1.0 dv for every unitwith the exception ofNaughton Unit 3 

### (104 dy). The predicted number ofdilYS above 0.5 dv for the LNB/OFA option was 40 for Naughton Unit 3, and 16 or less for each of the other twelve units. The Division determined that SCR would be required on

AQD LRS BART 000477..._'"._.**-_:~_._---,-_** ..

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Basin.Electric Laramie River Station
. DecisionDocument, BART PermitApplication, AP-6047 Page 4 of23 Naughton Unit 3 to bring about additional NOx emissions reductions and modeled visibility improvement, and these factors differentiated the Naughton Unit 3 BART analysis from the others. 

### It was the fbll consideration of all five statutory BART factors, principally the pronounced visibility improvement for 

### LNB/OFA as compared to baseline. and the lack of non-air quality environmental impacts that led the Division to conclude that

### LNB/OFA would be BART for NOx control at the Jim Bridger plant and for Units 1 and 2 at the Naughton Plant. Modeled visibility impacts for Naughton Unit 3 were reduced to levels comparable to those yielded by 

### LNB/OFA controls on Naughton Units 1 and 2 only through the addition of SCR as BART on Naughton Unit 3. Potential energy losses and environmentil! impacts from the operation of SCR were mentioned in the Division's BART analysis for both the Naughton and Jim Bridger plants, but were'only part ofthe larger evaluations thatconsidered all five statutory factors. 11.4 NOx Controls: SCR Efficiencies

- The Forest Service commented that greater SCR control efficiencies shouldbe factored into the cost andvisibility analyses. Response

- The Division coriducted a search ofthe EPA RACTIBACTILAER Clearinghouse (RBLC) to find NOx emission limits as BACT associated with SCR control in recently issued permits. Table 2 presents a summary ofthe Division's RBLC search. Two plants have limits of 0.05 IblMMBtu NOxwith a 12-monthrolling average, which is significantly longerthan a 3D-day. averaging period. Because the 0.05 IblMMBtu limits are based on a 12-month averaging period, they are notcomparableto the 3D-day limits establishedbythe.Division.Thetwoplants with 30= day averaging periods will be subjected to either a 0.08 Ib/MMBtu or·0.07 Ib/MMBtu limit, and the limits established by the Division meet these lower limits. A spreadsheet compiled by the National Park Service with a summary ofnationwide BART determinations shows that both units outside ofWyoming for which SCRis proposed as BART will be subject to aNOxemission limit of0.07 IblMMBtu, and both will bebased on a3D-day averaging period. The RBLC search showed tWo plants that will be subjectto 24-hour NOx limits ofless than 0.07 IblMMBtu (0.067 Ib/MMBtu), but these limits are for newly constructed plants which have been engineered to meet these levels. BART will require the retrofit ofsignificant controls at plants that were not designed to meet these lower levels. Based on the Division's evaluation, the Division is satisfied that the NOxemission limit of0.07 IblMMBtll (3D-day rolling average) that was evaluated for SCR control under BART is the most stringent control level likely to be achieved in aretrofit.

AQD LRS BART 000478.,
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II.S 

### SOLControls (Section 309)

- 

### The Forest Service understands the role of Section 309 in exempting the State ofWyoming from making BART determinations for 

### 802controls based on the demonstration that the benefits from 

### 802emissions reductions under Section 309 exceed those that would have resulted from BART. Are the existing S02 controls in place at the Jim Bridger and Naughton plants at least equivalentto the control scenario used in the demonstration, Le., are the existing controls needed to accomplish the "Better than BART" demonstration for Section 309? They also note that the 309 program sunsets in 2018 and added S02 controls may be needed for reasonable progress atthattime.
. Response

- The State otWyoming submitted a 309 SIP as is allowed by the Regional Haze Rule. Part ofthe SIP submittal is a "Better than BART" demonstration, required by rule, which does not require that each and every unit demonstrate emission controls that are "Better than BART". The demonstration is aregional demonstration. The Division is aware than the 309 program only establishes milestones through 2018, and that following 2018 another strategy may be necessary to reduce visibility-impairing pollutants. Additional strategies will be addressed in future SIP revisions.

AQD LRS BART 

### 000479BasinElectricLaramie River Station DecisionDocument, BART PermitApplication, AP-6047 Page 6 of23 

# m. Analysis ofComments from EPA Region 8: III.I Background Ozone Concentration in CALPUFF

- EPA Region 8 commented that the Division's visibility modeling used 44 ppb as a background ozone concentration .as the default value for periods when measured data was missing. This value appears to be too low based on the average annual concentrations at sites near the facilities (ThunderBasin = 50-55 ppb, Jonah = 55-58 ppb). DEQ should provide an analysis of how higher ozone background concentrations would affectresults. Response

- The default ozonebackground concentration is used by CALPUFF as a domain-wide substitute for any hour for which all measured ozone concentradons are missing. For the Division's visibility modeling for BART, hourly ozone concentrations measured at seven monitoring stations spaced across the'modeling domain were input to CALPUFF. A visual inspection ofthe ozone files that were input to CALPUFF reveals that at least one valid ozone observation was available for every hour of the modeled period (2001-2003), making it unnecessary forthe model to usethe defaultbackground of44 ppb. Although the model did not use the default background value for the BART analyses, the Division calculated annual average concentrations for recent years (2007-2008) and all available data for 2009 for many ofthe stations that were used for input to CALPUFF, including Thunder Basin,' Jonah, Rocky Mountain National Park, Centennial, and Pinedale. Annual averagevalues forthese stations ranged from 35 ppb to 49 ppb, with an overall average ofapproximately 40 ppb. -The Division is confident that the default background value of44 ppb was appropriate forthe BART modeling, and thatthere is no needfor additional analyses to explore alternatebackground concentrations. III.2 Weight ofVisibility Modeling Results in BART Determinations

- EPA Region 8 commented that DEQ should provide an explanation ofhow modeled visibility improvements were weighed in making BART determinations. Response

- The Division's BART determinations were based on consideration of all five statutory factors, as required by EPA's Appendix Y BART guidance. The modeled visibility improvements for a given control strategy were one ofthe five factors that were considered. No single factor was weighted as being more importantthan another, because the Division looked at all five statutory factors in their entirety. EPA guidance did not provide a quantification ofthe amount ofmodeled visibility improvementthat would be acceptable or significant.
.The Division used two metrics that were mentioned in the EPA BART guidance, the 98th'percentile resultfor a given year and the level at which a source "contributes" to visibility degradation (0.5 Adv), to present the results ofthe BART visibility modeling. Also see the response to USDA Forest Service comment 11.3. III.3 Cumulative Modeled Impacts -.EPA Region 8 commented that cumulative, modeled Class I . impacts from all units at a facility (or combined impacts from multiple faciiities) should be presented in'additionto the results for individual units. Response

- The visibility impacts from BART-eligible sources are to be modeled separately. As stated 

### in the EPA'.s Appendix Y guidance, relative to the use ofthe CALPUFF model for BART determinations, "We believe that CALPUFFis an appropriate applicationjorStates to usejar the particularpurposes ojthis rule, to determine 

## if an individual source is reasonably anticipatedto

AQD LRS BART 000480BasinElectric LaramieRiver Station DecisionDocument, BARTPermitApplication, AP-6047 Page 7 of23
cause or contribute to impairment ofvisibility in -Class I areas, .and to predict the degree of visibility improvement which could reasonably be anticipated to resultfrom the use ofretrofit technology

### f!!. an individualsource. We encourage States to use itfor thesepurposes." [emphasis added] IlIA Language from BART Determinations

- EPA Region 8 commented that the Division should clarify the statements of "3-year average visibility improvements". Are dv improvements calculated for each Class I area added together? Ifso, what is the meaning ofthe number? Are three Class I areas sufficientto quantify cumulative impacts? Were all Class I areas within 300 km considered?
. Response

- To arrive at the "3-year average visibility improvements" that were reported in the Division's BART analyses, the modeled 98th percentile dv change or the number ofdays above 0.5 dv predicted for a given year ofmeteorology was averaged with the similar result from the other two years ofmeteorology. These 3-year average values were determined for each modeled Class I area separately, and were devised to allow a straightforward, direct comparison ofone' control optionto another. Regarding the sufficiency ofthe numberofmodeled Class I areas and the question of other Class I areas within 300 

### km, see response to USDA Forest Service comment 11.1. III.5 NO!..Controls

- EPA Region 8 commented that the most stringent emission control levels for NO" controls have not been evaluated, resulting in inflated calculated cost effectiveness values. Lower emission limits should be evaluated for selective non.catalyticreduction (SNCR) and SCR. Response

- The Division has analyzed the most stringent levels for SNCR and SCR, and does not agree that the cost effectiveness numbers have been inflated. See response to USDA Forest Service comment 11.4. Furthermore, the Division has deemed the costs associated with all analyzed BART NO" control options, including SNCR and SCR, to. be reasonable (see the conclusions listed under the section: NOx: EVALUATE IMPACTS AND DOCUMENT RESULTS in each ofthe five BART Application Analyses). III.6 PM Controls: Averaging Periods- EPA Region 8 commented thaithe BART conclusions and the permitconditions should include associated averaging periods for all PM/PMlOlimits. Response

- The averaging periods for the PMIPM\o limits are dictated by the performance test requirements in the BART permits. Compliance with the Ib/MMBtu and lb/hr PMlPMlO limits is based onthe average ofthree I-hour tests per 40 CFR 60.46. III.7 PM Controls: Control Effectiveness

- EPA Region 8 commented that the Division should .explain why 0.015 Ib/MMBtu for baghotise/fabric filter control effectiveness is acceptable, when 0.012 IblMMBtu has been approved by the Division for other permits and 0.010 IblMMBtu was approved for the Desert Rock project. The BART determinations should include analyses of electrostatic precipitators (ESPs) and baghouses at lower control levels.
. Response

- Recent Prevention ofSignificantDeterioration (PSD) permits issued by the Division did include PMlPM10 limits of 0.012 Ib/MMBtu for fabric filter controls, but those limits (and .PMlPMlO limits established for the pesert Rock Project in New Mexico) were determined through Best
.Available Control Technology (BACT) analyses for new sources. The BART

AQD LRS BART 000481BasinElectricLaramie River Station , DecisionDocument, BARTPermitApplication, AP-604'( Page 8 of23 process deals with retrofit controls on existingunits, and therefore is not directly comparable to BACT determinations. Additionally, visibility modeling described in the Division's BART analysis for the Jim Bridger Plant showed that the addition of a fabric filter to replace an Electrostatic Precipitator (ESP) provided very little 

### in the way ofvisibility improvement, with predicted cumulative improvements across three Class I areas ofonly 0.03 to 0.1**~dv** for Units 1- 4. These results indicate that requiring more stringent control levels for a fabric filter would not , provide significant visibility improvement. As described on page 18 ofthe Division's BART analysis, ESP performance enhancements are already in use atthe Laramie River Station. 

### ilL8 PM Controls: Permit Exemption

- EPA Region 8 commented that Condition 5 inthe proposed EOU BART permits contains an inappropriate exemption for startup. The exemption from the lb/MMBtu PM limit during startup should be removed or it may be appropriate to analyze the needfor astartup BART limit. Response

- For each EOU subject to BART in Wyoming, only the BART limits for PMlPMlO that are expressed in IblMMBtu will not apply during startup. The BART limits for PMlPMlO that are expressed in lb/hr and tpy (as based on the IblMMBtu limits) 

### will. apply during all operating periods including startup, The Division considers the BART limits expressed in terms of lb/hr and tpy to be appropriate limits for startup. For the four units at the Jim Bridger plant, PacifiCorp calculated that the particulate emissions from the startup fuel (fuel oil) would be no greater than 10.9 lb/hr per unit,

__ conservatively. assuming that the ESP controls had zero control efficiency during the startup

process. As a comparison, the BART limit that would apply for each unit during startup is 180 lb/hr. Further, PacifiCorp has agreed to minimize startup emissions from the four units at the plant by placing the ESPs in service prior to the introduction of coal to the 'boilers, which is , contrary to the manufacturer's recommendation to energize the ESP only after the unit is at full operatingtemperature and combustion offuel.oilhas ceased. Similarly forUnit 1 at Wyodak, particulates are controlledby an ESP and startup is accomplished with fuel oil. The maximum emissions estimated for startup (8.9 lb/hr) would be well below the BART limit of71 lb/hr. The three units at LRS are also started on fuel oil and controlled with' ESPs, and the particulate emissions during startup are expected to be well below the BART limits, which are set at 193 lb/hrto 198 lb/hrforthethree units. For units with baghouse controls for particulate'matter such as Dave Johnston Units 3 and 4, emissions from fuel oil during the startup process are also estimated to be well below the allowable lb/hr BART limits. In the case oftheNaughtonplant, particulate controls will include a mixture ofESPs (Units 1 and 2) and afabric filter/baghouse (Unit 3). Natural gas is the startup fuel for each ofthese units, and particulate emissions during startup are expected to be well below the established lb/hr BART limits. ' 

### IlL9 

### SOl Controls: Reasonable Progress

- EPA Region 8 commented that the Division must evaluate the visibility impacts ofS02controls and demonstrate reasonable progress for the Class I areas away from the Colorado Plateau.

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BasinElectric Laramie River Station DecisionDocument, BARTPermitApplication, AP-6047 

### Page 9 of23 Response

- Wyoming, along with other 309 states in the WRAP region, evaluated the impact of the 309 program on ail Class I areas in the west, even though the requirement by rule was to demonstrate improvement in Class I areas on the Colorado Plateau. The WRAP modeling for sulfates shows that all Class I areas in and around Wyoming are benefiting from the sulfur dioxide emission reductions instituted in the 309 program. Sulfate extinction levels show improvement onthe 20% worst days and improvement or at leastno degradation on the 20% best days. Furthermore, the Regional Haze rule allows a state to take full credit for strategies implemented under 309 when addressing Class I Areas away from the Colorado Plateau (51.309(g)(4)(i)). IlLIO FGC for PM Control atLaramie River Station

- EPA Region 8 commented that no additional PM controls were considered for Laramie River Station (LRS). The Division should evaluate if flue gas conditioning (FOC) would be a suitable low-cost option. Response

- The commenter was incorrect, because FOC was evaluated. Page 18 of the Division's BART analysis includes a description ofFOC at the LRS. The Division concluded that FOe would not substantially reduce PM emissions, so FGC was eliminated from consideration inthe BARTreview. IILII Control Levels for LNB, OFA, and LNB/OFA

- EPA Region 8 questions why separate evaluations of multiple potential NOx 

### controls for Units 1-3 at the Laramie River Station all arrived at the same control level (0.23 Ib/MMBtu) for differenttechnologies. LNB, OFA, and a LNB/OFA combo are all listed with 

### the same controlled rate. Also, LNB/OFA cost is much 

# higherfuanforPadfiCorp units, why? '.-

- Response

- Computational Fluid Dynamics (CFD) modeling ofthe LRS boilers conducted for Basin Electric indicatedthat the addition of new LNB would not be capable ofreducing NOx' 

### emissions to levels any lower than could be achieved with the proposed OFA alone. However, the LRS boilers would benefit from new LNB because ofthe ability to operate the burners at the proper stoichiometric ratio and to maintain a stable flame. As described in a letterto the Division from Basin Electric dated September 10, 2009, LRS already is equipped with early versions of LNB. The burners were modified in the mid-1990's, which lowered NOx

### emissions from about 0.45 Ib/MMBtu to about 0.27 IbIMMBtu. Due to existing boiler geometries, the addition ofOFA with the existing low NOx 

### burners has the potential of reducing NOx 

### emissions to 0.23 Ib/MMBtu. This would only be possible with the existing burners ifthey were able to be staged down to a 0.90 stoichiometric ratio and have stable flames. New burners are primarily designed forthe abilityto stage down to a0.90 stoichiometric ratio and to maintain stable flames. Because the Division has deemed the costs associated with LNB/OFA to be reasonable for the LRS and for all ofthe PacifiCorp plants, an explanation for differences in cost estimates by Basin Electric andPacifiCorp is notrelevant. III.l2 SCR for NO!..Control- EPA Region 8 commented that the Division's BART analysis for LRS requires that add-on NOx

### controls at or below 0.07 IblMMBtu be installed on one ofthe LRS boilers by December 31,2018, and on a second LRS unit by December 31, 2023. Ifsuch a limit is achievable at LRS, it should be required as BART. Also, greater levels oicontrol should be examinedforNOx'

AQD LRS BART 000483

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BasinElectric Laramie River Station DecisionDocument, BARTPermitApplication, AP-6047 Page 10 of23 

# _ ........,

. Response

- The Division's BART determinations for the Laramie River Station were based on

consideration ofall five statutory BART factors in their entirety, as required by EPA's Appendix Y BART guidance. A BART determination does not rely 011 a single factor such as the level of control thatcan be achieved. Regarding greater levels ofNOx control for SCR, a letter to the Division from Basin Electric dated September 10, 2009 states that an emission rate of0.07 Ib/MMBtu is the best performance that can be expected from retrofitting an SCR on the existing LRS boilers. These boilers, which were built in the late 1910's, were not designed to accommodate the addition ofan SCR between the reheat superheater and the airheater. Thus, the spacing andthe temperature offlue gas are not optimum for an SCR.. New power plants can be designed with a taller boiler and spacing appropriate for an SCR and with the specific temperature distribution through the boiler to provide more effective reduction ofNOx' The design ofan SCR is much different for a retrofit than for anew facility. Also see response to USDA Forest Service Comment ITA. IV. Analysis ofComments from PacifiCorp: 

### N.l General Comments: Cost Metrics

- PacifiCorp commented that EPA's Appendix Y BART guidance states that a proper BART evaluation should include "other cost-effectiveness measures (such as $/deciview)". Thus, any BART determination that is limited to use. only cost effectiveness and incremental costeffectiveness may be unacceptablynarrow. .

.. ..Response

## =EPA's Appendix Y BARl' guidance does mentionthat"dollars perdeciview" ($/dy) is a metJ:ic that could be used to evaluate the cost of BART compliance, but by no means identifies $/dv as an essential or required metric. The Division considered capital cost, annual cost, cost effectiveness, and incremental cost effectiveness in the cost evaluation of each proposed BART control option. The Division chose not to use a hybrid metric such as $/dv primarily because ofthe lack ofhistorical precedent regarding reasonable/acceptable. levels for such a metric. Additionally, the use ofa hybrid cost metric such as $/deciview can introduce uncertainty as to how the value was calculated. The value of"/deciview" could be based on the highest modeled value in a.given area orthe 98th percentile modeled value. It could be based on the 9801 percentile value for anyone modeled year or itcould be an average for multiple years. 

### It could even be based on an average modeled value across an entire Class I area or the sum of deciview changes across multiple areas. The Division has found that $/dv values are often presented without explanation of the basis for the calculation. To avoid these confounding factors, the Division chose to evaluate and present the cost analyses and visibility analyses separately.
. 

### N.2 General Comments: Cost Effectiveness

- PacifiCorp commented that any BART determination requiring a source to install post-combustion controls like SCRor spend more than $1,500 perton ofNOxremoved would be contraryto EPA AppendixYBART guidance. Response

- The EPA's Appendix Y guidance describes the EPA's selection ofpresumptive NOx limits for coal-fired EGUs, and provides approximate cost levels for meeting the presumptive limits with current combustion controls and a somewhathighercostlevel for a subset ofunits that would require advanced combustion controls such as rotating opposed fire air (ROFA). The EPA guidance does not attemptto establish cost**threshold~** that would be considered unreasonable for a given control technology, nor does it present the approximate costs associated with the presumptive levels as absolute limits above which cost should be deemed unreasonable. The

AQD LRS BART 000484BasinElectric Laramie River Station DecisionDocument, BARTPermitApplication, AP-6047 Page 11 of23 guidance also states that states may in specific cases find thatthe use ofSCR is appropriate. As stated previously, the Division established NO. emission limits for BART based on consideration ofall five statutory factors in theirentirety, as requiredbythe Appendix Y guidance. IV,3 General Comments: Power Plants More Than 750 MW

- PacifiCorp commented that Appendix 

### Y indicates that states must follow Appendix Y guidelines in making BART determinations on a source-by-source basis for 750 MW plants. Wyoming rules impose similar requirements forpowerplants greaterthan 750 MW. Response

- The Division followed EPA and State ofWyoming rules for the BART analyses. Specifically, the Division followed WAQSR Chapter .6, §9(c)(ii), which states that power plants with generating capacities greater than seven hundred fifty megawatts shall comply with EPA Appendix Y, and that Appendix Y should be used as guidance for preparing BART analyses for all otherfacilities. IVA General Comments: Post-Combustion Controls

- PacifiCorp commented that EPA never contemplated the use of p.ost-combustion controls to meet BART limits for tangentially-fired boilers, and that it is nearly impossible under Appendix Y guidance to show that anything other than combustion controls should berequired as BART. Response

- See response to PacifiCorp commentIV.2.

- -TV.5-uGeneral. Comments: Visibility Improvement_=PacifiCorpcommented_ that .aBARL determination that only relied on the 98th percentile, three-year average results from CALPUFF may be too narrowto satisf)rAppendixY.
. Response

- The Division did

### n~t rely solely on the three-year average of the 98th percentile CALPUFF results to evaluatethe expected visibility changes for the BART control options. The 98th percentile values and the number ofdays with predicted results above 0.5 dv were presented 

### in the Division's BART analyses for each ofthree modeled years, for each Class I area, and for each control option. The three-year average ofthe 98th percentile results and the number ofdays above 0.5 dv were chosen for graphical representation and were mentioned prominently in the Division's conclusions because they offered the clearest comparison of one control option to another (see graphs in Appendix A). IV.6 General Comments: Modeling

- PacifiCorp commented that visibility. modeling contains inherent bias or exaggeration because it assumes that a particular source will operate at its maximum capacity 100% ofthe time and thateach unit at afacility operates in the same way. Response

- The results from BART visibility modeling, as required by EPA guidance, are based on daily (24-hour) averages. Reported results for a given control scenario, expressed in units of deciviews, represent the predicted change in visibility as compared to natural background over the course of24-hour periods ofmeteorology. The modeled emission rates for a given unit at a power plant should reflect the highest rate ·that could be achieved over a 24-hour period, and therefore the assumption that a given unit is operating at its maximum operating capacity is appropriate for each unitat abase-loadpowerplant such as JimBridger or Laramie River Station. Additionally, the conclusions drawn from BART visibility modeling primarily involve comparisons between control scenarios for which the emissions are determined similarly.

AQD LRS BART 000485....-....

### \

BasinElectric LaramieRiver Station DecisionDocument, BARTPermitApplication, AP-6047 Page 12 of23 

### N.? General Comments: NO!.Emissions

- PacifiCorp commented that emissions ofNO. during the 20% best and 20% worst days at Class I areas in.Wyoming are not a significant contributor to regional haze as compared to other emissions, and therefore the Division should consider this beforerequiring extreme NO. control measures such as SCRas BART. Response

- Forthe 20% worst days during the years 2000-2004 at the BridgerWilderness Area, 6.21 % of the total visibility degradation was attributable to nitrates; Source apportionment modeling provided by the WRAP showed that 19% ofthe nitrates come from Wyoming sources. The Division recognizes that pollutants other than nitrates contribute more toward the total visibility degradation at the Bridger Wilderness Area, but the Division has concluded that the contribution from Wyoming sources toward the formation ofnitrates at the Bridger Wilderness Area and other Class I areas warrants a full consideration ofprospective NO. controls under the BART process. . 

### N.8 Perceptibility

- PacifiCorp commented that credible studies indicate that only changes in visibility as high as 1.5-2.0' dv are perceptible to the human eye. The Division should consider this while drawing conclusions based on the results of the visibility modeling and before requiring extreme NO. control measures such as SCR. Response

- The Division did not attempt to endorse a particular threshold for human eye "perceptibility" since the level ofperceptibility has long been disputed. Instead, the Divisionhas relied onEPA's AppendixYBART guidance, which suggests avalue of0.5 dv as the level that a '-, source "contributes" tovisibilityimpairment. One ofthemetrics used bythe Divisionto evaluate ., the relative benefit ofa given BART control option was the number ofdays yielding a modeled impact of0.5 dv ormore. 

# v. .Analysis ofComments from the National Park Service: V.1 NOLStep 

### 1: Identify Available Retrofit Control Technologies'- The NPS commented that Basin Electric's cost analysis is flawed because they omitted the most effective NO. control technology (LNB-OFA-SCR). Response

- Basin Electric's 

### BARTanalysis did include the combination ofOFA, newLNBs, and SCR. The performance ofthe SCRwas based on**inst~llation** after OFAlLNB. V.2 NOiStep 3: Evaluate Effectiveness ofRemaining Control Technologies (SCR capabilities)- The NPS commented that the Division underestimated the ability of SCR 

### to reduce emissions. The proposed NO. limit for SCR (0.07 lblMMBtu) is not low enough. SCR can achieve greater reductions. NPS suggests 0.06 Ib/MMBtu for 30-day limit, 0.05 Ib/MMBtu or lower for an annual limit. Response

- See response to USDAForest Service comment 

### ITA. V,3 NO!.Step 4: Evaluate Impacts and Document'Results (SCR costs)

- The NPS commented that SCR costs were generally overestimated because the OAQPS Control Cost Manual was not used for cost estimates. Response

- BasinElectric developed cost estimates for SCR control using a combination ofCoal Utility Environmental Cost (CUECost) estimates, vendor-obtained cost data, and estimates from

AQD LRS BART 000486BasinElectric LaramieRiver Station DecisionDocument, BARTPermitApplication, AP-6047 Page 13 of23

, previous in-house design/build projects. The degree to which the SCR costs may have been

overestimated does not require further review because the Division has concluded that the estimated costs are reasonable and that costs alone would notprecludethe use ofSCR. VA NO!...Step 4: Evaluate Impacts and Document Results (incremental costs for SCR)

- The NPS commentedthatthe Division over-emphasized the incremental costs for the addition ofSCR in the BART determinations. The Division should consider the average costs calculated for combustion controls plus SCR. Response

- See'response to PacifiCorp comment

### N.1 and NPS commentV.3. V.S NO!.Step 4: Evaluate Impacts and DocumentResults (basis for costs)

- The NPS commented that cost estimates' shouldbe'documented by vendor orbythe EPA Control CostManual. Response

- Seeresponse to NPS commentV.3. V.6 NO,LStep 5: Visibility Improvement Determination (Class I Areas Modeled)

- The NPS commented that the Division should consider visibility impacts at all Class I areas within 300 kilometers (km) ofa source. Response

- Seeresponse to USDA Forest Service comment 11.1. V.7

- -- NO!.Step 5: Visibility ImprovementDeteJ!mination fincJ!emental benefits ofSCR)..-.The NJ>S commented that the Division placed too much emphasis on the incremental improvement in visibility that was predicted for the addition ofSCR. The total predicted visibilitY improvement resultingfrom acombination ofcontrol options shouldhave been presented. Response

- The incremental improvement in modeled visibility with the addition of SCR was mentioned prominently in the summary ofthe Division's BART conclusions, but all visibility modeling results were considered. For'more information on the presentation ofthe visibility modeling results in the Division's BART analyses, see the response to EPA Region 8 comment III.2 and PacifiCorp's comment IV.5. V.8 BART Conclusions for NO!.Controls: $/dv

- The NPS commented thatthe Division should use $/dv as an additional metric for evaluatingBART controls. Response

- Seeresponseto PacifiCorp response IV.l. V.9 BART Conclusions for N0,LControls: Cost Benchmarks

- The NPS commented that the Division determined that the costs for SCRwere reasonable, yet rejected SCR for BART control. DEQ should explain why andprovide the cost benchmarks used to determine reasonable costs. ' Response

- The Division established NOx emission limits for BART based on consideration of all five statutory factors (as required by EPA's Appendix Y BART guidance) and not merely based on cost. The Division relied on past experience 'with BACT determinations for similar sources/control options to determine the range ofcontrol costs thatwere reasonable.

AQD LRS BART 000487·**~''''''''**

BasinElectric Laramie River Station Decision Document, BARTPermitApplication, AP-6047 

### Page 14 of23**-~.** \ ./



### V.lO BART Conclusions for NOLContro!s: Non-Air Quality Impacts

- The NPS commented that the Division mentioned non-air quality impacts as reasons to reject SCR for BART controls. RecentPSD permits issuedby DEQ and requiring SCR did not mention such impacts. Why were such impacts mentioned in these particular cases? SCR has been used at many facilities with minimal problems with transport and storage ofammonia, why wouldthis be aparticularproblem for SCR as BART control? Response

- The Division's BART determinations were based on consideration of the five statutory factors, including the cost of compliance and the energy and non-air quality environmental impacts ofcompliance. Potential energy losses and environmental impacts from the operation ofSNCR and SCRwere**m~ntioned** 

### in the Division's BART analysis, butwere only part ofthe largerevaluation thatconsidered all five statutory factors. V.l1 BART Conclusions for NOLControls: Non-Air Quality Impacts (continued)

- The NPS commented that the Division mentioned parasitic power loss in association with the operation of OFA and SCR. Parasitic power loss associated with SCR has already been accounted for in the cost analysis for NOx 

### and should not be "double-counted" by using it to draw conclusions for BART control unless it would cause a power shortage. The NPS commented that the Division stated that the operation of SCR could impact the "salability" offly ash. Evidence should be presented and the economic impactquantified. The NPS also commented thatthe Division stated that SCR could create "blue plume" ifthe ammonia injection rate is not well conirolled. NPS states thatitassumes that aplantoperatorcanproperly controlthe injectionrate. Response

- See response to NPS commentV.lO. V.12 BART Conclusions for PMlll

### Controls: Control Effectiveness

- The NPS commented that the Division should explain why 0.015 Ib/MMBtu was acceptable to the Division as a control effectiveness for a ESP/polishing fabric filter combination, when 0.012 Ib/MMBtu has been approved by the Division for other recent permits involving fabric filters and limits as low as 0.010 IblMMBtu haverecently been approved for fabric filters (e.g., DesertRockProject). Response

- See response to EPARegion 8 commentIII.7. V.l3 BART Modeling: Baseline NO! and SOLEmission Rates

- The NPS commented that the Division should provide confirmation ofthe basis for the.modeled emission rates for the baseline scenario. Response

- As shown in Table 16 (page 32) ofthe Division's BART analysis for the Laramie River Station, NOx

### and S02 emissions for the baseline modeling scenario were based on annual averages for 2001-2003. Ifthe baseline emissions had been based on 24-hour maximum rates or permit limits, the modeled visibility impacts for baseline would have been higher, and the modeled visibility improvementwiththe BART controls chosen bythe Division would have been more pronounced. The Division's BART determinations for the Laramie River Station were based on all five statutory factors in their entirety, and higher modeled visibility impacts for the baseline scenario would nothave changedthe determinations.

AQD LRS BART 000488

## -**~"""**

BasinElectricLaramie River Station Decision Document, BART PermitApplication, AP-6047 Page 15 of23 VI. Analysis ofComments from thePowderRiverBasin Resource Council: VI. 1 SCR as BART

- The Powder River Basin Resource Council commented that SCR is the best available retrofittechnology and should berequired as BART at all ofthe Wyoming power plants under consideration. Response

- The Division determined BART for the control ofNOxemissions from power plants in Wyoming based on afull consideration ofall five statutory factors in their entirety, as required by EPA's Appendix Y BART guidance. The BART guidance does not dictate that a state require
" the controltechnology with the highest level ofcontrol in all cases. " VIT. Analysis ofComments from the PowderRiverBasin Resource Council, et aI.: VII. 1 Modeled Class I Areas

- The Powder River Basin Resource Council, et a1. commented that all Class I areas within 300 

### km ofagiven source shouldbe modeled forvisibility impacts. Response

- Seeresponse to USDA Forest Service commentn.l. VII.2 SCR as BART

- The Powder River Basin Resource Council, et aJ. commented that SCR is BART and mustbe required for all units at all coal-fired powerplants. Response

- SeeresponsetoUSDA Forest Service comments and II.3. VIIJ Section 309 Milestone Program

- The Powder RiverBasin Resource Council, et aJ. commented that DEQ should impose BART limits for S02 because participation in the Section 309 program only excuses DEQ from setting BART limits ifthe State's 309 SIP is approved by the EPA and if the 309 SIP demonstrates that emissions levels would result in greater visibility improvement than source-specific BARTlimits. Response

- The Regional Haze Rule allows"the State ofWyoming to submit a 309 SIP in lieu of establishing BART limits for S02. The 309 SIP submittal includes a "Better than BART" demonstration. The entire submittal is currently undergoing EPA review and the State has no control over how long the EPA takes to review the SIP. The State, however, does not wait for EPA to complete its review before implementing a SIP. All of the 309 states have been participating in the 309 program, collecting S02 inventories, allowing independent audits ofthe information, comparing the regional totals to the milestones, and taking public comment on the regional figures and the comparisons with the milestone figures. The 802 levels have shown compliance with the milestones and continue to demonstrate declining S02 emissions levels. Also see responses to USDA Forest Service commentII.S andEPA comment III.9. VilA Reasonably Attributable Visibility Impairment

- The Powder River Basin Resource Council, et a1. commented that because of the magnitude of modeled visibility impacts, DEQ should certify that Wyoming power plants are causing reasonably attributable visibilitY impairment, and establish more stringent BART controls. A single source that is responsible for a 1.0 deciview change or more should be considered to "cause" visibility impairment, according to WAQSR Chapter 6, §9(d)(i)(A). Because ofthe reasonably attributable visibility impairment, BART must be determined under WAQSR Chapter 9, §2(d)(ii) and 40 CFR §51.302(c)(4)(iii). These regulations provide that BART is presumed to be at least at NSPS levels
.. This would require at least 0.11**lb/~tu** for NO. limits, but SCR should be required at 0.Q7 lbl1V1MBtu.

AQD LRS BART 000489Basin Electric Laramie River Station Decision Document, BART PermitApplication, AP-6047 Page 16 of23 Response

- WAQSR Chapter 6, §9(d)(i)(A) applies to the determination ofwhich sources in Wyoming are subject to BART under the regional haze program, and is not relevant to the determination of

### reasonably attributable visibility impairment. Since adoption of Wyoming's Visibility .SIP and visibility regulations to address 

### reasonably attributable visibility impairment, neither the Federal Land Managers ofany Class I area nor the Division has certified that visibility impairment, attributable to a source or small group ofsources, exists in any Wyoming Class I area pursuantto provisions in Chapter 9, Section 2 ofthe WAQSR. The provisions ofChapter 9, Section 2 ofthe WAQSR are therefore notrelevantto the Division's BART analyses. VII.5 SCR for Long-Term Strategy

- The Powder River Basin Resource Council, et a1. comrriented that the BART limits determined by the Division for the three units at the Laramie River Station (0.23 lblMMBtu) meetpresumptive BART, butfurther reductions are warranted to reduce Class I impacts. The Division will require SCRto be installed on two ofthe LRS units under Long-Term Strategy by 2023, but no explanation is given for the extension beyond the 5-year deadline for BART. Response

- The Division determined BART for NOxcontrol at the Laramie River Station based on consideration of all five statutory BART factors, as required by EPA's Appendix Y BART guidance. No single factor was weighted as being more important than another, because the Division looked at all five statutory factors in their entirety. The BART determination for NOx control on all three units included low NOx burners (LNB) with overfire air (OFA). The Division's BART analysis provides the basis for the BART determination ofLNB with OFA as

-- well as why SCRwas not determined to be BARL The BART permit conditions that are associated with Long-Term Strategy have been included 

### in the August 25, 2009 draft ofWyoming's Regional Haze SIP withoutmodification. The particular Long-Term Strategy requirements, in this case add-on NOx controls for two units at the Laramie River Station, are established as enforceable on the source by the Division through inclusion in the BART permit. 

### VIII. Analysis ofComments from the Sierra Club and Citizens Associated with the Sierra Club: VIII.l Air Quality Laws and Regulations

- The Sierra Club commented that it is important that air quality laws and regulations are strictly complied with to preserve park resources for present and future generations. Response

- The Division followed federal regulations and guidance as well as state regulations in assessing the BART applications and for making the BART determination for all sources eligible for BART in the State of Wyoming. The BART rules and guidance used by the Division in9luded:

• Section 308 ofthe Regional Haze Rule [40 CFR 51.308(e)]


### • Guidelines/orBARTDeterminations Under theRegionalHaze Rule [Appendix Y to part 51]
• Chapter 6, Section 9 ofthe Wyoming Air Quality Standards and Regulations (WAQSR), 

### BestAvailableRetrofit Technology

AQD LRS BART 000490BasinElectric Laramie River Station Decision Document, BARTPermitApplication,**AP~6047** Page 17 of23 VIII.2 Regional Haze Rule

- The Sierra Club commented thatthe State ofWyoming can and should do moreto protect air quality as the Regional Haze Rule is implemented.
. Response

- The Division's BART determinations for Wyoming sources, as well as additional air pollution controls that will be required to further reduce regional haze, will be addressed in the Wyoming State Implementation Plan (SIP) for regional haze. The SIP incorporates the emissions reductions associatedwith the Long-Term Strategy for regional haze. VIII.3 Control ofNitrogen Oxide Emissions

- The Sierra Club commentedthatthe State ofWyoming should requirethe coalplants to install devices thatreduce nitrogen oxide emissions. Response

- All ofthe Division's BART determinations for coal-fired power plants inthe State of Wyoming include pollution control equipment that 

# will substantially reduce nitrogen oxide emissions. VIllA 20-Year Trend

- A commenter stated that the amount of air and water pollution has clearly escalated in the past 20 years, with little reIieffor citizens or for the health offorests and the environment. Response

- The Division's BART determinations and otherrequirements under the regionalhaze program will result 'in large, state-wide emission reductions for three visibility-impairing pollutants; nitrogen oxides (NOx), particulate matter (PMlPMIO), and sulfur dioxide (S02). As an

. example, BART controls at the Jim Bridger plant-will result in a total annual reduction-in·

potentialNO.emissions ofapproximately 13,500 tons peryear. VIII.5 Wind Power - A commenter stated that Wyoming can readily replace aging' coal-fired power plants with wind power to protectpublic health and to protect our national parks and wilderness areas. Response

- The BART program is designed to assess Best Available Retrofit Technology on existing sources ofairpollution, including the existing power plants in the State. The Division's BART determinations will result in significant reductions in air pollutants from several power' plants in Wyoming, but complete replacement ofthe power plants with an alternate source of energy is well beyondthe scope ofthe BARTprogram. VIII.6 Pollution Reduction from PowerPlants - A commenter stated that Wyoming has an obligation to protect treasured public spaces by adhering to federal air quality laws'. The State must reduce air pollutants from the old coal plants that are federally required to utilize the most advanced technical developments in ensuring that airpollution is minimized.
. Response

- The Division determined BART controls based on the five statuto!)' factors developedbythe EPA. Various control technologies were evaluated for each source subject to BART, including the "most advanced technical developments", but the ultimate BART determinations were made based on. a full consideration of all five statutory factors in their entirety.

AQD LRS BART 000491_.....

BasinElectric Laramie River Station Decision Document, BART PermitApplication, AP-6047 Page 18 of23 VIII.7 SCR Controls

- Several commenters stated that BART for NOxcontrol should be SCR for all plants. Response

- Seeresponses to USDA Forest Service comments IIJ. IX. Analysis ofPublic Comments: IX.I SCR Controls

- Several commenters stated that BART for NOx control should be SCR for all plants. Response

- Seeresponses to USDA Forest Service comments II.3
.

.X. Analysis ofComments from Basin Electric Power Cooperative: X.1 PermitCondition 16

- Basin Electric requested thatthe Divisionrevise BART Permit Condition 16 for the LRS to change the time for submitting a permit application for additional add-on NOx controlfrom sixyears priorto installationto two years priorto installation. Response

- The Divisionwill make the requested change inthe final BARTpermitforthe LRS. XI. Decision:

.... On the basis oLcomments received during the publiQQommeilt**p~ri.Q4,JlJl _8.!rnly~i~**  

### Qf**!h9~~** comments, and representations made by BasinElectric, the Department ofEnvironmental Quality has determined that the permit application filed by Basin Electric complies with all applicable Wyoming Air Quality Standards and Regulations and that a BART permit will·be issued for the Laramie River Station. All ofthe conditions proposed inthe Division's analysis will be included inthe permitwiththe following changes (in bold):

- 16. Basin Electric shall submit permit applications for the installation of additional add-on NOx control on two units at the Laramie River Station to the Division no later than two (2) years prior to installation, under the Long-Term Strategy ofthe Wyoming §308 Regional Haze State Implementation Plan. It shall include an analysis ofthe four statutory factors and the. associated visibility impacts from the application of each proposed NOx control and resulting emission levels. This application shall address each add-on NOx control as a system of continuous emissions reduction achieving the lowest ·viable NOx emission, not to exceed a maximum of 0.07 IblMMBtu on a 3D-day roIling average as measured by a certified CEM. Additional add-on NOx control shall be installed and operational on one (1) unit by December 31, 2018 and on a second unitby December31; 2023.
. Datedthis 31stday ofDecember, 2009.

# Da~det~ Administrator Wyoming Air Quality Division

# Jj**~J/2v-** Jo
. Corra D ctor Wyoming Dep1,lrtment ofEnvironmental Quality

AQD LRS BART 000492--_._- ---------_.--_._--_._- '-----_
.._--"
---- --._--_.

__._-----------_._--_ -._.------_.._

### _-_.

__..

### _

### __._----_._.

__ _.

### __.._--_._.._--- ..

# _.__ __._---_._._._-----_. -_.- _.---_. ----_._- _. _.-_.-._,. -

_ 

### _- '.



## .APPENDIXA VISIBILITYMODELINGRESULTS (Baseline vs. LNB and SCR)

AQD LRS BART 000493Figure 1 Modeled BARTImpacts in BridgerWilderness Area Naughton and JimBridgerPoweiPlants: 98thPercentile (delta-dv)
['J\ Baseline Nau Ui = Naughton Unit 1 (160 MW) Nau U2 = Naughton Unit 2 (210 MW) Nau U3 = Naughton Unit 3 (330 MW) JB Ul =Jim Bridger Unit 1 (530 MW) JB U2 =Jim Bridger Unit 2 (530 MW) JB U3 = Jim Bridger Unit 3 (530 MW) JB U4 = Jim Bridger t)nit 4 (530MWj • LNBjOFA III LNBjOFA + SCR 2.500 "TI-------------------------'---------------------------

/ ./

(Modeling results representthe three-year average using 2001-2003 meteorology) 

### 0» 00**~O** <Or -l'-;:o

(f) 

### jl; -;- 'i' 2l a; 

## .e. 2.000 

### +1-------

1.500

1.000

0.500

0.000 Nau Ul Nau U2 Nau U3 J8 U2· J8 U3 J8 U4Figure2 Modeled BARTImpacts inWind CaveNationalPark Wyodak, DaveJohnston, and LaramieRiver**~tation** PowerPlants: 98th Percentile (delta-dv)

.....'

LRS U3 LRS U2 LRSU1 LRS Ul

### =Laramie RiverStation Unit 1 (550 MW) LRS U2

### =Laramie RiverStation Unit2 (550 MW) LRS U3

### = Laramie River ptation Unit3 (550 MW) Wyodak=335 MW DJ U3 = Dave Johnston Unit3 (230 MW) OJ U4

### =DaveJohnston Unit4 (330 MW)

1.500 I**~,~f----'----**

0.500 1.000

0,000 Wyodak OJ U3 OJ U4 (Modeling results representthethree-year average using2001-2003 meteorology) 

## >- "9 Qj 

## e.

0» 00**~O** <Or 01;0

en llJ 

### » ;0 -I

### Figure3 Modeled BARTImpacts in BridgerWilderness Area Naughton and JimBridgerPowerPlants: #

### Days> 0.5 deIta-dv

i

. : _.' rJ Baseline II 

### LNBjOFA II LNBjOFA

### +SCR Nau Ul = Naughton Unit 1 (160 MW) Nau U2 = Naughton Unit 2 (210 MW) Nau U3 = Naughton Unit 3 (330 MW)



## o JB Ul =Jim Bridger Unit 1 (530 MW) JB U2 =Jim Bridger Unit 2 (530 MW) JB U3 = Jim Bridger Unit 3 (530 MW) JB U4 = Jim Bridger Unit 4 (530 MW) 60 

## .,--------------------=-------------------------

·50 +1-------

40

til 30 Cl 

## .:::.
20 

# W")**r.4:'~~** 

# r"L II 

# P**~f~_ !ij',~**  .**~; ;~** 

# ~i**~~11 ~~**  

### ."".11

# f~ :"r.Vi::; 

### "

## m~:**!~'A~I l:g,'.;~**  .'

### r~~~**~i;~~ ~it!ii** 

### ~~1**;~\.".** 10

(Modeling results represent the three-year average using 2001-2003 meteorology) 

### 0» 00**~o** <Or <»;;0

(IJ ;;0 -I Nau Ul Nau U2 Nau U3 I J8 Ul J8 U2 J8 U3 J8 U4Figure 4 Modeled BARTImpacts inWind CaveNationalPark Wyodak, DaveJohnston, and LaramieRiver StationPowerPlants: # Days> 0.5 deIta-dv
Wyodak

### = 335 MW DJ U3 = Dave Johnston Unit 3 (230 MW) DJ U4

### =Dave Johnston Unit4 (330 MW) LRS Ul

### =Laramie River Station Unit 1 (550 MW) LRS U2 = Laramie River Station Unit 2 (550 MW) LRS U3

### =Laramie River Station Unit 3 (550 MW) E:l Baseline

.. LNBjOFA III LNBjOFA 

### + SCR 60**""Ti------------------~---------------------**

50 +1--------

40 +1--------,

<iI >- 30

20

10



# o /'



### 0» 00**~O** <Dr -.J:;o

(JJ 

### jl; :;0 -I. Wyodak DJ U3 OJ U4 (Modeling results representthe three-yearaverage using 2001-2003 meteorology) LRS U1 LRS U2 LRS U3