### \



### IN THE MATTER OF A PERMIT APPLICATION (AP-6040) FROM PACIFICORP FOR A

,BEST AVAll.ABLE RETROFIT TECHNOLOGY (BART) PERMIT FOR THE JIM 

### BRIDGER

POWERPLANT DECISION I. Introduction: The Air Quality Division received a BART permit application from PacifiCorp for the four coalfired boilers that operate at their Jim Bridger Power Plant in Sweetwater County, Wyoming. Regulations governingthe BART programhave been established by the U.S. EPA in 40 CFRPart 51

-AppendixY. As stated in the regulations, a source is eligible forBART ifitbelongs within a particular group ofstationary source categories, was not 

### in operationpriorto August 7, 1962, was in existence on August 7, 1977, and has the potential to emit 250 tons per year (tpy) or more of any visibility impairing air pollutant. Fossil fuel boilers with more than 250 million Btu (MMBtu) perhour heat input are listed as an eligible source type. Each ofthe four boilers at the Jim Bridgerplanthas aheat input of6,000 MMBtu perhour, andthe boilers were in existence on August 7, 1977. Potential emissions from each boiler for two visibility impairing air pollutants, nitrogen oxides (NOJ and sulfur dioxide (802), exceed 250 tpy and therefore the units are eligible forBART. TheDivision conducted an analysis ofthe BART permitapplicationfor the Jim Bridgerplant and on June 3,2009, published in the Rock Springs Daily Rocket-Miner apublic notice and notice of

,public,hearing of the proposed intent to issue BART determinations. Copies of the BART application and the Division's analysis were placed in the Sweetwater County Clerk's office in Green River, Wyoming,.jn accordance with regulations. A 63-day public notice period ran from June 3, 2009 to August 4,2009, and a public hearing was held on August 4,2009, at 6 p.m. in Room 1309 at Western Wyoming Community College, located at 2500 College Drive in Rock Springs, Wyoming. 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 Augusn, 2009 from EPA Region 8; 3) a letter datedAugust4,2009 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 received July 20, 2009 from Joanna Taylor; 7) a letter dated July 16,2009 from Andrew H. Salter; 8) a letter received July 20,2009 from Evelyn and Marvin Griffin; 9) a letterreceived July 23, 2009 from Mimi McMillen; 10) a letterreceived July 24, 2009 from William M. Anderson; 11) a letterreceived July 24,2009 from Rebekah Smith; 12) a letter dated July 24, 2009 from Mike Shonsey; 13) a letter dated July 24, 2009 from Susie Mohrmann; 14) a letter dated July 28, 2009 from Janice H. Harris; 15) a letter dated July 28,2009 from M. Christensen; 16) a letter dated July 27, 2009 from Clint Morrison; 17) a letter dated August 3,2009 from Ann Fuller; 18) a letter dated August 3, 2009 from Mary Fenton; 19) 725 unsigned letters received under a signed cover letter dated July 28, 2009 from Brad Mohrmann, Sierra Club Associate Regional Representative; and 20) 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 letter after the close ofthe public notice period from the Colorado Department ofPublic Health and Environment (letter dated September 14, 2009) in support of the Division's BART determinations for the Dave Johnson and Jim Bridgerpowerplants. 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

AQD Jim Bridger BART 

### 002792PacifiCorp JimBridgerPower Plant Decision Document, BART PermitApplication, AP-6040 Page 2 of27 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 Division also received positive comments supporting this project. TheDivision appreciates these comll).ents butthey are notincluded inthis documentas no response is required. TheDivision received numerous comments that were descriptive ofenvironmental impacts otherthan the impacts from BART-eligible sources in Wyoming on Class I area visibility. The Division's responses are limitedto the comments thatdealtwiththe 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 at the Division's

- BART analyses. These comments will be addressed by the Division as itprepares the response to comments onthe Regional Haze SIP.

- 

## n. Analysis ofComments from the USDAForestService: II. 1 BART Conclusions for NO! Controls: SCR for Jim Bridger

- The Forest Service commented that based on their review ofthe five statutory BART factors, -Selective Catalytic Reduction (SCR) should be BART for NOxcontrol for all units atthe Jim Bridger power plant. The Forest Service applauds the proposal to install SCRatthe four units atthe Jim Bridger plant for a longterm strategy, but SCRs atJim Bridger shouldbe installed as BART on all units by 2015-2016. Response

- The Division determined BART for NOx control at the Jim Bridger power plant based on consideration ofall five statutory BART factors, as required by EPA's Appendix Y BART guidance. No single factor was weighted as being more importantthan another, because the Division looked at all five statutory factors in their entirety. The BART determination for NOx control on all four units included low NOxburners (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 notdeterminedto be BART. Regarding the installation ofadditional control equipment atthe Jim Bridgerplant, PacifiCorp is required by the BART permitto install SCR on JimBridgerUriit 3 in 2015 and Jim BridgerUnit 4 in 2016 as well as add-on NOxcontrol on Units 1 and 2 no later than 2023. The schedule for installation is based on the incorporation of SCR add-on control on these units under the longterm strategy component of Wyoming's SIP for regional haze as well as PacifiCorp's construction plan for pollution control projects. The schedule for the installation ofSCRcontrols at other plants is uncertain at this point due to the demands on PacifiCorp for compliance with BART and other regulatory programs. PacifiCorp operates 19 coal-fired units, 14 ofwhich are BART-eligible. Additional BART-eligible units are owned or partly owned in Arizona, Colorado, and Montana. Table 1 presents a summary ofthe pollution control projects that are included in PacifiCorp's construction plan through 2014.

AQD Jim Bridger BART 

### 002793PacifiCorp JimBridgerPowerPlant , Decision Document, BART Permit Application, AP-6040 Page 3 of27

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### .. " ,', , ", Table 1: Statusotfoliution'ControlFroiectsUndertake:nbv:PaCifiCofo ", S02Scrubbers New=N LNB Baghouse SOz/LNB PowerPlant Location Upgrade=U Installations Installations Proiect Status Hunter 3 Utah Installed 2008 Installed Completed Huntington 2 Utah 2007-N 2007 2007 Completed Cholla4 Arizona 2008- U 2008 2008 Completed JimBridger4 Wyoming 2008- U 2008 n/a Completed JimBridger 2 Wyoming 2009-U 2005 n/a Completed Dave Johnston 3 Wyoming 201O-N 2010 2010 Under Construction Huntington 1 Utah 2010-U 2010 2010 Permitted JimBridger 1 Wyoming 2010- U 2010 n/a Under Construction Naughton 2 Wyoming 2011-N 2011 n/a Under Construction Hunter 2 Utah 2011- U 2011 2011 Permitted JimBridger3 Wyoming 2011-U 2007 n/a Under Construction Wyodak Wyoming 2011-U 2011 2011 Permitted Dave Johnston4 Wyoming 2012-N 2009 2012 Under Construction Naughton 1 Wyoming 2012-N 2012 n/a Under Construction Hunter 1 Utah 2014-U 2014 2014 Permitted Naughton 3 Wyoming 2013 - U 2013 2013 Permitted II.2 BART Conclusions for SOLControls: WFGD for Jim Bridger

- The Forest Service commented that, based on their review of the five statutory factors for BART, wet flue gas desulfurization (WFGD) should be BART for SOz control for all units at the Jim Bridger and

,Naughton powerplants. Response

- WFGD upgrades have already been (or are scheduled to be) installed on all units at the Jim Bridgerplant. Forthe Naughton plant, WFGD is scheduledto be installed on Units 1 and 2 and WFGD is scheduled to be upgraded for Unit 3. BART limits for S02 will not be set because Wyoming is a §309 state participating in the Regional SOz Milestone and Backstop Trading Program. §308(e)(2) provides states within the TransportRegion addressed bythe Grand Canyon Visibility Transport Commission with the option to implement or require participation in an emissions trading program or other alternative measure rather than to require sources subject to BART to install, operate, and maintain additional control technology to meet, an established emission limit on a continuous basis. ll.3 NO! Step 5: Visibility Improvement Determination (Class I areas modeled)

- The Forest Service commented that 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.

AQD Jim Bridger BART 

### 002794

# -"\
PacifiCorp Jim BridgerPowerPlant Decision Document, BART Permit Application, AP-6040 Page 4 of27 Response

- Onlythose Class I areas most likely to be impacted by sources subjectto BART at a 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 Jor 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 notinclude 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 notto 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 (tgiven area orthe 98th percentile modeledvalue. 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 averagemodeled value across an entire Class I area orthe 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 andpresentthe costanalyses and visibility analyses separately.

,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 notrequiredto include itinthe 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**mode~ing** results for these Class I Areas in the proximity of Savage Run, the Division anticipates similar improvements invisibility from the analyzed emission reductions. ' 11.4 NOxStep 5: Visibility ImprovementDetermination (significant impact)

- The Forest Service commentedthat itis incorrectto dismiss acontrol strategy on the basisthatthe modeled visibility improvementis notperceptible or significant. Response -The Division used 0.5 dv as the threshold levelto exempta source from BART orto deem modeled impacts as insignificant. EPA's RegionalHaze 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 Air Partnership (WRAP) region. '

AQD Jim Bridger BART 

### 002795PacifiCorp JimBridgerPowerPlant , DecisionDocument, BARTPermitApplication, AP-6040 Page 5 of27 U.5 FiveFactorAnalysis forBART Selection: Coal Composition

- The Forest Service commented that PacifiCorp's analysis ofcoal composition is flawed and it does not meet the requirement for ademonstration ofwhypresumptive limits cannotbereached. Response

- Although the BART emission limitfor NO. exceeds the presumptive BART limitfor tangential-fired boilers burning sub-bituminous coal, PacifiCorp's analysis of coal composition was not a factor in the Division's determination. The Division established NO. emission limits for BART atthe Jim Bridger plantbased on consideration ofall five statutory factors, as required by EPA's Appendix Y BART guidance. The Division interpreted the presumptive emission levels for NO. and S02 as recommended control levels proposed by EPA after reviewing technical data related to BART. Requiring sources to meet presumptive emission levels was not required as one of the five statutory factors. Conversely, the Division did not automatically determine emission levels belowpresumptive levels to be BART; but considered all five statutory factors before making aBART determination. ,n.6 N0;LControls: SCR

- The Forest Service commented that significant, cumulative visibility improvements modeled for SCRinstallations atthe JimBridger and Naughtonplants indicatethat SCR should be BART for all units at those two plants. The Forest Service questions why DEQ chose SCR as BART only for Naughton Unit 3 when SCR costs 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' becausethey have already been considered inthe costanalysis. 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 atthe JimBridger and Naughton plants, but the Division's BART determinations for the two plants were based on consideration ofali five statutory BART factors, as required by EPA's Appendix Y BART guidance. PacifiCorp proposed ,a BART limit for NO. emissions from Naughton Unit 3 of 0.37 IblMMBtu, which would be achieved by tuning the existing LNB/OFA system. For Naughton Units 1 and 2, PacifiCorp proposed a BART limit for NO. of 0.26 IblMMBtu for each unit using new LNB/OFA. Visibility modeling showed that the NO. emission level proposed by PacifiCorp for Naughton Unit 

### .3 provided less in terms of modeled visibility reductions from baseline as compared'to otherunits atthe two plants. For example, Naughton Units 1 and 2 showed a 72% to 73% reduction in the number ofdays with predicted impacts of 0.5 dv or more at the nearest Class I area (Bridger 'Wilderness) for LNB/OFA as compared to baseline. The reduction for Naughton Unit 3 for LNB/OFA 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 ofNaughtonUnit 3 (1.4 dv). The predicted number ofdays 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 Naughton Unit 3 to bring about additional NO. emissions reductions and modeled visibility improvement, and these factors differentiated the Naughton Unit 3 BART analysis from the others. It was the full consideration of all five statutory BART factors, principally the pronounced visibility improvement for LNB/OF A as compared to baseline and the lack ofnon-air quality

AQD Jim Bridger BART 

### 002796\.
PacifiCorp JimBridgerPowerPlant DecisionDocument, BARTPermitApplication, AP-6040 Page 6 of27 environmental impacts that led the Division to conclude that LNB/OFA would be BART forNOx control atthe Jim Bridger plant and for Units I and 2 atthe Naughton Plant. Modeled visibility impacts for Naughton Unit 3 were reduced to levels comparable to those yielded by LNB/OFA controls on Naughton Units I and 2 only through the addition of SCR as BART on Naughton Unit 3. Potential energy losses and environmental impacts from the operation of SCR were mentioned in the Division's BART**an~lysis** for both the Naughton and Jim Bridger plants, but were only part ofthe larger evaluations that considered all five statutory factors. II.7 NOLControls: SCR Efficiencies

- The Forest Service commented that greater SCR control efficiencies should befactored into the cost and visibility analyses. Response

- The Division conducted a search ofthe EPA RACT/BACT/LAER 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 30-day averaging period. Because the 0.05 IblMMBtu limits are based on a 12-month averaging period, they are not comparabletothe 3D-day limits established by the Division. The two plants with 30- day averaging periods will be subjected to either a 0.08 Ib/MMBtu or 0.07 IblMMBtu 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 SCR is proposed as BART will be subjectto aNOxemission limit of0.07 IblMMBtu, andboth will be based on a 30-day averagingperiod. The RBLC search showed two plants that will be subjectto 24-hourNOxlimits ofless than 0.07 IblM:tv1Btu (0.067 IbIMMBtu), 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 Ib/MMBtu (30-day rolling average) that was evaluated for SCR control under BART is the most stringent control level likely to be achieved in aretrofit.

AQD Jim Bridger BART 

### 002797\
PacifiCorp JimBridgerPower Plant Decision Document, BARTPermitApplication, AP-6040 Page 7 of27 ,'"
....

- - Table 2: SCR**P~rDlifLiniits** from the

### RBLC--. --

-- ; Size of NO. Permit Limit(s) for Permit Facility/Location Source Source Description SCRControl Date John W. TurkPower 600MW 6,000 MMBtulhrPC Boiler 1) 0.067 Ib/MMBtu Nov 2008 Plant/Arkansas (PRB Coal)

-(24-hrrolling) 2) 0.05 Ib/MMBtu (l2-monthrolling)

rSCR, BACT] DryFork 385MW PC Boiler 0.05 Ib/MMBtu Oct2007 Station/Wyoming (12-monthrolling) [SCR, BACT] WYGEN3/Wyoming 100MW 1,300MMBtulhrPC Boiler 0.05 IblMMBtu Feb 2007 (12-monthrolling)

[SCR, BACT] Iatan 

## -- PCBoiler 0.081b1MMBtu

-Jan2006 Station/Missouri (30-dayrolling) [SCR, BACT] Big CajunIIPower 675MW PCBoiler 0.071b1MMBtu Aug 2005 Plant/Louisiana (annual average) -rSCR BACT] TS Power -200MW PC Boiler

- 0.067 Ib/MMBtu May 2005 PlantlNevadci (24-hourroHing) [SCR, BACT] OPPD

- Nebraska 

## - 

# -- om IblMMBtu Mar2005 City (30-dayrolling) StationlNebraska rSCR, BACTl Note: "--" mdlcates that thiS value was notprovIded IntheRBLC II.8**SO~** Controls (Section 309)

- The Forest Service und,erstands the role of Section 309 in exempting the State ofWyoming from making BART determinations for S02 controls based on the demonstration that the benefits from S02 emissions 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 thatthe 309 program sunsets in 2018 and added S02 controls may be needed forreasonable progress atthattime. Response

- The State ofWyoming submitted a309 SIP as is allowed bythe 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 a regional demonstration. The Division is awarethan 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. II.9 Visibility Impairment

- The Forest Service commented that because EPA BART guidelines state that 0.5 dv "contributes" to visibility impairment, and 1.0 dv "causes" visibility impairment, the discussion from Ronald Henry regarding perceptibility in the BART applications from PacifiCorp is irrelevant and used in an impropercontext.

AQD Jim Bridger BART 

### 002798PacifiCorp JimBridgerPowerPlant DecisionDocument, BARTPermitApplication, AP-6040 Page 8 of27 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 Division has relied on EPA's AppendixY BART guidance, which suggests avalue of0.5 dv as the level that a source "contributes" to visibility impairment. One ofthe metrics used by the Divisionto evaluate the relative benefit ofa given BART control option was the number ofdays yielding a modeled impactof0·.5 dv ormore. 

# m. Analysis ofComments from EPARegion 8: IILl 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 nearthe facilities (Thunder Basin = 50-55 ppb, Jonah = 55-58 ppb). DEQ should provide an analysis of how higher ozone background concentrations would affectresults. Response

- The default ozone background concentration is llsed by CALPUFF as a domain-wide substitute for any hour for which all measured ozone concentrations 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 (2607-2008) and all available data for 2009 for many ofthe**sta~ions** that were used for inputto CALPUFF, including Thunder Basin, Jonah, Rocky Mountain National Park, Centennial, and Pinedale. Annual average values for these 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 for the BART modeling, andthatthere is no need for additional analyses to explore alternate background 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 usedtwo metrics thatwere mentioned in the EPA BART guidance, the 98th percentile result for a given year and the level at which a source "contributes" to ·visibility degradation (0.5 .6.dv), to present the results ofthe BART visibility modeling. Also see the response to. USDA Forest Service comment 11.6.

AQD Jim Bridger BART 

### 002799PacifiCorp JimBridgerPowerPlant Decision Document, BARTPermitApplication, AP-6040 Page 9 of27 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 facilities) should be presented in addition to 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 applicationfor States to usefor the particularpurposes of this rule, to determine 

## if an individualsource is reasonably anticipatedto cause or contribute to impairment ofvisibility in Ciass I areas, and to predict the degree of visibility improvement which could reasonably be anticipated to resultfrom the use ofretrofit technology 

### ill @**individual~.** We encourage States to use it for thesepurposes." [emphasis added] 

### lIlA 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 sufficient to 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 

## agiven year ofmeteorology was averaged with the similar result from the othertwo 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. Regardingthe sufficiency ofthree modeled Class 

### I areas and the question ofother Class I areas within300 

### km, see response to USDA Forest·Service comment 11.3. 1II.5 N0;LControls

- EPA Region 8 commented that the most stringent emission control levels for NOx controls have not been evaluated, resulting in inflated calculated cost effectiveness values. Lower emission limits should be evaluated for selective non-catalytic reduction (SNCR) and SCR. Response

- The Div.ision 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 II.7. Furthermore, the Division has deemed the costs associated with all analyzed BART NOx 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 BARTApplicationAnalyses). Ill.6 12-Month Average for NO

### c EPA Region 8 commented thatthere is no formula to calculate if the 12-month rolling emission limit has exceeded the permit condition. A permit condition to match condition 12.a.iiifrom the LaramieRiver Station analysis should be created. Response

- The BART limits for NOx emissions from the PacifiCorp plants include 30-day rolling limits in terms ofIblIv.lMBtu and lb/hr. Theton per year limit is based on a calendar year ratherthan arolling average, andthereforethe formula associatedwiththe annual BART limitfor NOxatthe LaramieRiver Station is notrelevant.

AQD Jim Bridger BART 

### 002800PacifiCorp JimBddgerPowerPlant DecisionDocument, BARTPermitApplication, AP-6040 Page 10 of27 III.7 PM Controls: Averaging Periods

- EPA Region 8 commented that the BART conclusions and the permit conditions should include associated averaging periods for all 

### PM/PMlO limits. Response

- The averaging periods for the PM/PM10 limits are dictated by the performance test requirements in the BART permits. Compliance with the Ib/MMBtu and lb/hr 

### PM/PM10 limits is based on the average ofthree I-hourtests per40 CFR 60.46. III.8 PM Controls: Control Effectiveness

- EPA Region 8 commented that the Division should explain why 0.015 IblMMBtu for baghouse/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 PM/PMlO limits of 0.012 Ib/MMBtu for fabric filter controls, but those limits (and PM/PMlO limits established for the Desert Rock Project in New Mexico) were determined through Best Available Control Technology (BACT) .analyses for new sources. The BART process deals withretrofitcontrols 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 Ll.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 17 ofthe Division's BART analysis, ESP performance enhancements using FGC were considered, and will be utilized for BART control forUnits 1-4 attheJim Bridgerplant.
. III.9 PM Controls: PermitExemption

- EPA Region 

## 8commented that Condition 5 in the proposed EGU BART permits contains an inappropriate exemption for startup. The exemption from the Ib/MMBtu PM limit during startup should be removed or it may be appropriate to analyze the need for a startup BART limit. Response

- For each EGU subject to BART in Wyoming, only the BART limits for PM/PMlO that are expressed in IblMMBtu will not apply during startup. The BART limits for 

### PM/PMJO that are expressed in lb/hr and tpy (as based on the Ib/MMBtu limits) will apply during .all operating periods including startup. The Division considers the BART limits expressed in terms oflb/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 operating temperature and combustion offuel oil has ceased. Similarly for Unit 1 atWyodak, particulates are controlled by anESP and startup is accomplished with fuel oil. The maximum emissions estimated for startup (8.9 lb/hr) would be well below the

AQD Jim Bridger BART 

### 002801PacifiCorp JimBridgerPowerPlant DecisionDocument, BARTPermitApplication, AP-6040 Page 11 of27 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 Ib/hr to 198 lb/hrforthe three 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/hrBART limits'. In the case ofthe Naughton plant, particulatecontrols will include amixture 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 Ib/hr BART limits. 

### IIUO PM Controls: FGC

- EPA Region 8 commented that flue gas conditioning (FGC) must be applied only after FGD is installed or upgraded to avoid increases in the emissions of sulfuric acid (H2S04) mist. A control option should notbe considered as aBART optionifitwill resultin an increase invisibility-reducingpollutants. Response

- The Division has already evaluated the impacts ofFGC at the Jim Bridger plant as part ofthe review ofPacifiCorp's permit application for permitMD-1552, which was issued on April 9, 2007. PermitMD-1552 authorized new LNB with separated OFA for Units 1,3 and'4 and FGC to enhance the performance ofthe ESPs on Units 1-4. The permit application included a modeling evaluation ofthe impacts to Class I area visibility from the FGC, and the impacts were predictedto be insignificant. 

### ,III. 11 

### Sal Controls: Reasonable Progress

- EPA Region 8 commented that the Division must evaluatethe visibility impacts of802controls and demonstratereasonable progress forthe Class I areas away from the Colorado Plateau. Response

- Wyoming, along with other 309 states in the WRAP region, evaluated the impact of the 309 program on all 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 sources 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)). III.12 CALPUFF Visibility Modeling: Other Class I Areas

- EPA Region 8 commented that visibility impacts at Flattops Wilderness Area in Colorado should have been modeled for the Jim Bridger and Naughtonplants. Response

- See response to USDA Forest Service comment 11.3. III.13 Presumptive Levels for NO!.

- EPA Region 8 commented that notenough information has been presented to explain why the proposed BART NOx limits for the Jim Bridger plant exceed the presumptive BART limits. Jim, Bridger should be able to achieve lower limits closer to the

AQD Jim Bridger BART 

### 002802PacifiCorp JimBridgerPowerPlarit
. DecisionDocument, BARTPermitApplication, AP-6040 Page 12 of27 presumptive levels given that two units (2 & 3) are already achieving 0.22 Ib/MMBtu with LNB/OFA. Response - A letter from PacifiCorp to the Division dated September 16, 2009 provided informationrelative to this comment: "Actual operations of the low-NO" burners at the Jim Bridger plant provide additional justificationfor the 0.26 Ib/mmBtu limit on a 30-day rolling average. Three ofthe Jim Bridger units have already been modified with the best available low NO" burners and over-jire air technology. On an annual basis, the units have been able to achieve emission rates ranging from 0.21 to 0.24 Ib/MMBtu. However, actual operating experience has demonstrated that during periods when mill maintenance isperformed, or during times ofhigh coal variability, the units may have difficulty meetinga 30-day rollingaverage of 0.26lb/MMBtu. " The Division concurs with PacifiCorp's assessment that a limit of0.26 Ib/MMBtu on a 30-day rolling average is appropriate as a BART limit for NOx emissions from each unit at the Jim Bridgerplant. III.14 SCR as BART

- EPA Region 8 commented that if0.07 Ib/MMBtu NOx is achievable by Jim Bridger Units 1 & 2 with SCR, it needs to be set as a BART limit rather thanpostponed under reasonable progress. Response

- See response to Forest ServicecommentILl. III.1S New Combustion Controls

- EPA Region 8 commentedthat SNCR and SCR costare higher for Unit 2 than for other units, apparently because new LNB/OFA is not assumed. The State should provide an analysis onwhy new combustion controls could notbe applied. Response

- As described on page 4 ofthe Division's BART analysis for the Jim Bridger plant, permit MD-1138 was issued to PacifiCorp on April 1,2005 to authorize the installation ofnew LNB with separated OFA on Unit2 atthe plant. Because the emissions reductions from baseline with SNCR and SCRthat were calculated for Unit 2 already include the operation ofLNB/OFA, the magnitude ofthe NOxreductions from Unit 2 are lower and the cost per ton ofreduction values forUnit2 are higherthanfor the otherunits atthe plant. III.16 Collateral Impacts

- EPA Region 8 commented that PacifiCorp and the Division state that the installation ofSNCR or SCR attheJim Bridgerplant could impactthe "saleability" offly ash and that SCR could create a "blue plume" ifthe ammonia injection rate is not well controlled. The fact that injection rates may not be well controlled should not be a reason to eliminate a technology such as SNCRin amodem powerplant. Response

- The Division's BART determinations for the Jim Bridger plant were based on consideration ofthe five statutory factors, including the cost ofcompliance and the energy and non-air quality environmental impacts ofcompliance. Potential energy losses and environmental impacts from the operation ofSNCR and SCRwere mentioned in the Division's BART analysis, but were only part of the larger evaluation that considered all five statutory factors in their entirety.

AQD Jim Bridger BART 

### 002803PacifiCorp Jim BridgerPowerPlant DecisionDocument, BARTPermitApplication, AP-6040 Page 13 of27 IIL17 Unit 2 Emissions

- EPA Region 8 commented that the Division should explain why calculated NO" emissions reductions from baseline atthe Jim Bridger plant are differentfor Unit 2 vs. Units 1,3, and 4. Response

- See response to EPARegion 8 commentlIL15. III.I 8 Analysis ofSNCR

- EPA Region 8 commented that SNCR was not carried forward t9 Step 5 of the BART analysis. DEQ should complete an analysis ofthe modeled visibility improvements associatedwith SNCR.
. Response

- PacifiCorp, at the direction of the Division, modeled the range of anticipated visibility improvements from the company-proposed BART controls (LNB with separated OFA) and the addition ofSCRto those controls. While new LNB with OFA

### +SNCRand existing LNB with ROFA were not individually evaluated in Step 5, the anticipated degree of visibility improvement from applying either of those control options lies within the modeled range of visibility impacts. Since the costs associated with controls were all deemed reasonable, the visibility assessmentwas conductedforthe least and most stringent controls. IV. Analysis ofComments from PacifiCorp: IV.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 unacceptably narrow. Response

- EPA's Appendix Y BART guidance does mention that "dollars per deciview" ($/dv) is a metric 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 of a 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 or the 98u , percentile modeled value. It could be based on the 98u1 percentile value for anyone modeled year or it couldbe 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. IV.2 General Comments: CostEffectiveness

- PacifiCorp commented that any BART determination requiring a sourceto install post-combustion controls like SCR or spend more than $1,500 perton ofNO" removedwould be contraryto EPA AppendixY BART guidance. Response

- The EPA's AppendixY guidance describes the EPA's selection ofpresumptive NO" limits for coal-fired EGUs, and provides approximate cost levels for meeting the presumptive limits with current combustion controls and a somewhathigher cost level for a subset ofunits that would require advanced combustion controls such as rotating opposed fire air (ROFA). The EPA

AQD Jim Bridger BART 002804PacifiCorp Jim BridgerPowerPlant Decision Document, BARTPermitApplication, AP-6040 Page 14 of27 guidance does not attemptto establish cost thresholds 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 guidance also states that states may in specific cases find that the use ofSCR is appropriate. As stated previously, the Division established NO, emission limits for BART at the Jim Bridger powerplantbased on consideration ofall five statutory factors in their entirety; as required by the· AppendixY**gu~dance.** 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 for powerplants 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 post-combustion'controls to meet BART limits for tangentially-fired boilers, and that it is nearly impossible under Appen4ix Y guidance to show that anything other than combustion controls should be required as BART. Response

- Seeresponse to PacifiCorp commentIV.2. IV.5 General Comments: Visibility Improvement

- PacifiCorp commented that a BART determination that only relied on the 98th percentile, three-year average results from CALPUFF may be too narrowto satisfy AppendixY. ' Response

- The Division did not rely solely on the three-year average of the 98th percentile CALPUFF results to evaluate the 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 9801 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 AppendixA). 

## rv.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 that each unit at a facility 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

AQD Jim Bridger BART 

### 002805.'\ I PacifiCorp Jim BridgerPowerPlant DecisionDocument, BARTPermitApplication, AP-6040 Page 15 of27 appropriate for each unit at a base-load power plant such as Jim Bridger. Additionally, the conclusions drawn from BART visibility modeling primarily involve comparisons between control scenarios for whichthe emissions are determined similarly. IV.7 General Comments: NO!..Emissions

- PacifiCorp commented that emissions ofNOx 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 before requiring extreme NO. controlmeasures such as SCRas BART. Response

- Forthe 20% worst days during the years 2000-2004 at the Bridger Wilderness 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 thatthe 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. IV.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 imd before requiring extreme NO. controlmeasures such as SCR. Response

- See response to USDAForest Service comment 11.9. IV.9 Long-Term Strategy

- Pa9ifiCorp commented that thatthe Division has proposed an aggressive schedule for installation of SCR on 

### Jim Bridger Units 1-4 under Long-Term Strategy for the Regional Haze SIP. It is premature to use a BART application analysis to propose emissions reduction requirements under aLong-Term Strategy which has notyet beenreleased. Response

- The BART permit conditionsthat are associated with Long-Term Strategy have been included in the August 25, 2009 draft ofWyoming's Regional Haze SIP without modification. The particular Long-Term Strategy requirements, in this case add-on NOx ·controls for Units 1 through 4 at the Jim Bridger plant, are established as enforceable on the source by the Division through inclusion inthe BART permit. IV.IO PresumptiveBART

- PacifiCorp commentedthatthe Division's reference inthe BART analysis for the Jim Bridger plant to a presumptive BART limitforNO. of0.15 IblMlVIBtu is not correct. For reasons stated in PacifiCorp's most recent submittals to the Division, primarily an argument regarding coal characteristics, the correct presumptive BART limit for Jim Bridger Units 1-4 is 0.28 IblMlvIBtu. Response

- Seeresponse to USDA Forest Service comment 11.5.

AQD Jim Bridger BART 

### 002806PacifiCorp Jim Bridger Power Plant Decision Document, BARTPermitApplication, AP-6040 

### Page 16 of27 V. Analysis ofComments from the NationalParkService: V.1 NOx

### Step 3: Evaluate Effectiveness ofRemaining Control Technologies (SCR capabilities)- The NPS commented that the Division underestimated the ability of SCR to reduce emissions. The proposed NOx 

### limit for SCR (0.07 IblMMBtu) is not low enough. SCR can achieve greater reductions. NPS suggests 0.06 IblMMBtu for 30-day limit, 0.05 IblMMBtu or lower for an annual limit. Response

- See response to 

### USDAForest Service commentII.7. V.2 NO. Step 4: Evaluate Impacts and DocumentResults (SCR costs)

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

- PacifiCorp developed cost estimates for SCR control using a combination ofthe OAQPS Control Cost Manual, vendor-obtained price quotes, and a database developed by the engineering firm Sargent & 

### Lundy. 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 andthatcosts alone would notprecludethe use ofSCR. V,3 NO! Step 4: Evaluate Impacts and Document Results (Incremental costs for SCR)

- The NPS commentedthatthe Division over-emphasizedthe 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 commentIV.1 andNPS commentV.2. VA NO!..Step 4: Evaluate Impacts and DocumentResults (basis for costs)

- The NPS commented that cost estimates shouldbe documented 

### by vendor or

### bytheEPA Control CostManual. Response

- Seeresponse to NPS commentV.2. V.S NO. Step 

### 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

- See responseto USDA Forest Service commentII.3. V.6 NO!..Step 5: Visibility ImprovementDetermination (incremental benefits ofSCR)

- The NPS 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 resulting from a combination ofcontrol options should have beenpresented. 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

### N.S.

AQD Jim Bridger BART 

### 002807.PacifiCorp JimBridgerPower'Plant DecisionDocument, BARTPermitApplication, AP-6040 Page 17 of27

• 1.0% ofthe S02inthe boiler is convertedto S03

• An additional 1.0% ofthe S02is converted to S03 in an SCRunit

• The S03 is convertedto H2 S04mistin the flue gas
• 50% ofthe 

### H 2 S04mist is removed in awetFGD unit

• 95% ofthe H2 S04mist is removed in a dry FGD unit

• An SCRunithas 2.0 ppmvd

### NH3slip
Q 50% of the NH3 slip is converted to ammonium sulfate and 50% is converted to ammonium bisulfate

• 50% ofthe ammonium sulfate and bisulfate are removed in a wet FGD unit and 90% of the ammonium sulfate and bisulfate are removed in a dryFGD unit

• Total sulfate emissions are made up ofH2 S04mist, ammonium sulfate and ammonium bisulfate V.8 BART Conclusions for NO!.Controls: $/dv

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

- See response to PacifiCorp response 

### N .1. V.9 BART Conclusions for NO! Controls: Cost Benchmarks

- The NPS commented that the Division determined thatthe costs for SCRwere reasonable, yetrejected SCRfor BART control. DEQ should explain why and providethe costbenchmarks usedto determine reasonable costs. Response

- The Division established 

### NOxemission 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. VolO BART Conclusions for NO!..Controls: 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 issued by 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 would this be aparticularproblem for SCR as BART control? Response

- See response to EPARegion 

### 8comment

### m.'I6. v.II BART Conclusions for NO!..Controls: Parasitic Power Loss

- 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

AQD Jim Bridger BART 002808PacifiCorp JimBridger PowerPlant
. Decision Document, BARTPermitApplication, AP·6040 Page 18 of27 NOx· and should not be "double-counted" by using it to draw conclusions for BART control unless itwould cause apower shortage. Response

- See response to EPA Region 8 commentIII. 16. V.12 BART Conclusions for NO! Controls: Fly Ash Sales

- The NPS commented that the Division stated that the operation of SCR could impact the "salability" of fly ash. Evidence should be presented and the economic impact quantified. Response

- See response to EPA Region 8comment III. 16
.

.._.V.13 BART Conclusions for NOLControls: Ammonia Injection

- The NPS commented that the Division stated that SCR could create "blue plume" ifthe ammonia injection rate is not well controlled. NPS states that it assumes that PacifiCorp can properly controlthe injectionrate. Response

- Seeresponseto EPA Region 8commentIII.16. V.14 BART Conclusions for NOLControls: SCR Installation

- The NPS commented that PacifiCorp states that SCRwould take aminimum ofsixyears to plan and install. NPS states that Minnesota Power plans to install SCR, fabric filter, and a new chimney on the 330 MW Boswell Unit#3 in halfofthattime. PacifiCorp should explain why so much extratime· is needed. Response - A letter provided to the Division by PacifiCorp dated September 16,2009 provided information on the time needed to plan, design, and install SCR:

• Develop and Permit: 18-24 months

• Design: 9-12 months

• Procurement: 9-13 months

• Construct: 18-24 months

• Start, Tune, andTest 4-6 months

• Total (including overlap ofindividual tasks): 60-66 months V.15 BART Conclusions for PM10 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 Ib/MMBtu have recently been approved for fabric filters (e.g., DesertRockProject). Response

- See response to EPA Region 8 commentIII.8.

AQD Jim Bridger BART 

### 002809PacifiCorp Jim BridgerPowerPlant Decision Document, BART PermitApplication, AP-6040 Page 19 of27 VI. Analysis ofComments from the PowderRiverBasinResource Council, et aI.: VI. 1 Modeled Class I Areas

- The Powder River Basin Resource Council, et a1. commented that all Class I areas within 300 km ofa given source should be modeledforvisibility impacts. Response

- See response to USDAForest Service comment 

### IIJ. VI.2 SCR as BART

- The Powder River Basin Resource Council, et al. commented that SCR is BART and must be required for all units at all coal-fired powerplants. DEQ's schedule for SCR installation requires SCR on all four Jim Bridger units by 2023. No specific facts for allowing such an extension beyond the standard five-year BART schedule is 'given, only an undefined concemforPacifiCorp's "logistical challenge". Because PacifiCorp's Visibility modeling for the Jim Bridgerplant shows a 2.5 dv improvementacross "all 3 mostheavily impacted Class I areas" and because costs for SCR were deemed reasonable, SCR should be considered BART. Presumptive BART for NOx at'the Jim Bridger plant is 0.15 Ibf.MMBtu, but DEQ determined a BART limit of 0.26 lb/.MMBtu. DEQ failed to provide adequate justification for such a departure. SCR should be installed on all four Jim Bridger units to meet a NOx limit of 0.07 Ib/MMBtu in the next five years. Response

- See responses to USDA Forest Service comments II. 1, U.5 andII.6, and EPA Region 8 commentJILl3. VI.3 Section 309 MilestoneProgram

- The PowderRiverBasinResource Council, et a1. commented that DEQ should impose BART limits for S02 because participationin 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 BART limits. Response

- The Regional Haze Rule allows the State ofWyorriing 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 miiestone figures. The S02 levels have shown compliance with the milestones and continue to demonstrate declining S02 emissions levels. Also see responses to USDAForest Service commentII.8 andEPA comment III.1 L VIA Reasonably Attributable Visibility Impairment

- The Powder River Basin Resource Council, et al. 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, BARTmust 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 atNSPS levels. This would require at least 0.11 Ib/MMBtu forNOxlimits, but SCR should berequired,at 0.07 Ib/MMBtu.

AQD Jim Bridger BART 002810-'.
PacifiCorp JimBridgerPowerPlant Decision Document, BARTPermitApplication, AP-6040 Page 20 of27 Response

- WAQSR Chapter 6, §9(d)(i)(A) applies to the determination of which 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 ofWyoming's Visibility SIP and visibility regulations to address reasonably attributable visibility impairment, neitherthe Federal Land Managers ofany Class I area northe Division has certified thatvisibility impairment, attributable to a source or small group of sources, exists in any Wyoming Class I area pursuantto provisions in Chapter 9, Section 2 ofthe WAQSK The provisions ofChapter 9, Section 2 oftheWAQSR are therefore notrelevantto the Division's BART analyses. VI.5 BART Conclusions for PM10 Controls

- The Powder River Basin Resource Council, et al. commented that the Division should require PacifiCorp to meet, at aminimum, a PM limit O.QlS Ib/MMBtu at the Jim Bridger plant using full baghouse or polishing baghouse because: 1) the plant is causing reasonably attributable visibility impaiqnent in at least four Class I areas, and 2) because BART is supposed to be the "best system of continuous emission reduction" and the Division's analysis identified fabric filters as the most stringentPM control. Response

- The Division established 

### PM/PMlO emission limits for BART at the Jim Bridger plant based on consideration of all five statutory factors, as required by EPA's Appendix Y BART guidance. Various control technologies were evaluated for each source subjectto BART, including the most advanced controls, butthe**B~T** guidance does not dictate that a state require the control technology with the highest level ofcontrol in all cases. Regarding the relevance of reasonably attributable visibility impairment, see response to Powder River Basin Resource Council, etal. commentVIA. VII. Analysis ofComments from the Sierra Club and Citizens Associated with the Sierra Club: VII.1 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

- TheDivisionfollowed federal regulations and guidance as well as state regulations in assessingthe 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 included:
.

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

• Guidelinesfor BARTDeterminations Under the RegionalHaze Rule [Appendix Y to part 51]
• Chapter 6, Section 9 ofthe Wyoming Air Quality Standards and Regulations (WAQSR), BestAvailableRetrofitTechnology VII.2 Regional Haze Rule

- The Sierra Club commented thatthe State ofWyoming can and should do more to protectair quality as the Regional HazeRule 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 ImplementationPlan (SIP) for regional haze. The SIP incorporates the emissions reductions associated withthe Long-Term Strategy forregional haze.

AQD Jim Bridger BART 002811

## 1

:J

PacifiCorp JimBridgerPowerPlant DecisionDocument, BARTPennitApplication, AP-6040 Page 21 of27 VII.3 Control ofNitrogen Oxide Emissions

- The Sierra Club commented thatthe State ofWyoming should require the coalplants to install devices thatreduce nitrogen oxide emissions
.. Response

- All ofthe Division's BART determinations for coal-fired powerplants inthe State of Wyoming include pollution control
.equipment that will
.substantially reduce nitrogen oxide emissions. 

### VIlA 20-Year Trend

- A commenter stated that the amount of air and water pollution has clearly escalated in the past 

### 20 years, with little relieffor citizens or'for the health offorests and the environment. Response

- The Division's BART determinations and otherrequirements underthe regional haze program will result in large, state-wide emission reductions for three visibility-impairing pollutants; nitrogen oxides 

### (NOx), particulate matter (PMlPM10), and sulfur dioxide (S02)' As an example, BART controls at the Jim Bridger 'plant will result in a total annual reduction in potentialNOxemissions ofapproximately 13,500 tons peryear. VIL5 Wind Power - A commenter stated that Wyoming can readily replace aging coal-fired power plants with wind power to protect public 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 ofair pollution, including the existing powerplants 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. VII.6 Pollution Reduction from PowerPlants - A commenter stated thatWyoming has an obligation

.to protecttreasured public spaces by adhering to federal air quality laws. The State must reduce air pollutants from the old coal plants that are federa:Ily required to utilize the most advanced technical developments in ensuringthat air pollution is minimized. Response

- The Division determined BART controls based on the five statutory factors developed bythe 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**~~** . VIL7 SCR Controls

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

- Seeresponses to USDAForest Service comments 11.1 andII.6. VIII. Analysis ofPublic Comments: VIII. 1 SCR Controls

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

- Seeresponses to USDAForest Service comments 11.1 and

### n.6.

AQD Jim Bridger BART 

### 002812\
PacifiCotp JimBridgerPowerPlant DecisionDocument, BARTPermitApplication, AP-6040 Page 22 of27 IX. Decision: On the basis of comments received during the public comment period, an analysis of those comments, and**repr~sentations** made by PacifiCorp, the Department ofEnvironmental Quality has determined that the permit application filed by PacifiCorp complies with all applicable Wyoming Air Quality Standards and Regulations and that a BART permit will be issued for the Jim Bridger Power Plant. All ofthe conditions proposed in the Division's ana.lysis will be included inthe permit. No permit conditions required revision as a result ofthe public comment period. Datedthis 31 st'day ofDecember, 2009.

# Da~~ Administrator WyomingAir QualityDivision o V.Corra rector WyomingDepartment ofEnvironmental Quality

AQD Jim Bridger BART 

### 002813

## APPENDIXA 'VISIBILITYMODELING RESULTS (Baseline vs. LNB and SCR)

AQD Jim Bridger BART 

### 002814

### Figure 1 ModeledBARTImpacts in BridgerWilderness Area Naughton and JimBridgerPowerPlants: 98thPercentile (delta-dv) P'l Baseline Nau U1 = Naughton Unit 1 (160 MW) Nau U2

### =Naughton Unit 2 (210 MW) Nau U3 = Naughton Unit 3 (330 MW) JB U1 = 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) • LNBjOFA Il!l LNBjOFA + SCR 2.500 ",----------..,---------------------------------------------

.-'

(Modeling results representthe three-yearaverage using 200:1.-2003 meteorology) 

## 0» 00**~o** --"c.... (J1 

### 3' OJ ::!, a. lC CD

..... 

### :::u -I :;- "'i' 10 ±: Q.I 

## .e. 2.000 +1--------

1.500

1.000

0.500

0.000 I ;'-".'-'- Nau Ul Nau U2 Nau U3 JB Ul JB U2 J6 U3 JB U4Figure2

. Modeled BARTImpacts inWind CaveNationalPark Wyodak, Dave Johnston, andLaramieRiver StationPowerPlants: 98th Percentile (delta-dv)
Wyodak

### = 335 MW DJ U3 = DaveJohnston Unit3 (230 MW) DJ U4

### =DaveJohnston Unit4 (330 MW) LRS U1 = Laramie RiverStation Unit 1 (550 MW) LRS U2

### =Laramie RiverStation Unit2(550 MW) lRS U3= Laramie RiverStation Unit3(550 MW) i£l Baseline II LNB/OFA '11 LNB/OFA

### +SCR

(Modeling results representthethree-yearaverage using2001-2003 meteorology) 

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2.000

1.500 +1-------<

'1.000

0.500

0.000 Wyodak DJ U3 DJU4 lRSUl LRS U2 LRS U3 , .jFigure 3 Modeled BART Impacts in BridgerWilderness Area Naughton and Jim BridgerPowerPlants: #Days> 0.5 delta-dv

(Modeling results representthe three-yearaverage using 2001-2003 meteorology) Nau Ul = 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 Unit4 (530 MW)


## , .

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JB U4 r.;j Baseline

• LNBjOFA iI LNB!OFA

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JB U3 JB U2 JB Ul Nau U3 Nau U2 Nau U1 

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40

10 20 30 ltl o 

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## » :::0 --lFigure4 Modeled BART Impacts inWind CaveNationalPark Wyodak, DaveJohnston, and Laramie River StationPowerPlants: # Days> 0.5 delta-dv
Wyodak= 335 MW OJ U3 = OaveJohnston Unit 3 (230 MW) OJ U4= OaveJohnston Unit4 (330 MW) LRS UI

### =Laramie River Station Unit I (550 MW) LRS U2 = Laramie River Station Unit 2 (550 MW) LRS U3 = Laramie River Station Unit 3 (550 MW) Ejj Baseline

• LNBjOFA !Ill LNBjOFA

### + SCR 60 T,-----------------------------------------

LRS U3 LRS U2 LRS Ui 

### o Wyodak OJ U3 OJ U4 (Modeling results representthethree-yearaverage using 2001-2003 meteorology) 40 +1------- 50 +1--------

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