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

,-- ) \

I

IN THE MATTER OF A PERMIT APPLICATION (AP-6047) FROM BASIN ELECTRIC

POWER COOPERATIVE FOR A BEST AVAILABLE RETROFIT TECHNOLOGY (BART)

PERMIT FOR THE 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 if it 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 of any visibility impairing air

pollutant. Fossil fuel boilers with more than 250 million Btu (MMBtu) pefJ hour heat input are

listed as an,eligible source type. Units 1 through 3 at the Laramie River Station have heat inputs

of 6,420-6,600 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 the units 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 of public hearing of the proposed, intent to issue BART determinations. Copies of the

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 a public hearing was held onAugust6,2009,atlp.m; at thePlatte County Library, located at 904 9th Street in 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 letter received 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 Clint Morrison; 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 letter from Basin Electric dated August 5,2009.

Due to the number of public 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 ••• _,-", __ • __._. •••__._•••__••

Basin Electric Laramie River Station

Decision Document, BART Permit Application, AP-6047

Page 2 of23

Division also received positive comments supporting this project. The Division appreciates these

comments but they are not included in this document as no response is required.

The Division received numerous comments that were descriptive of environmental impacts other

than the impacts from BART-eligible sources in Wyoming on Class I area visibility. The

Division's responses are limited to the comments that dealt with 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, but were principally directed at the Division's

BART analyses. These comments will be addressed by the Division as it prepares the response to

comments on the Regional Haze SIP.

II. 'Analysis of Comments from the USDA Forest Service:

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

Service commented that all.class I areas within 300 km of a given source should be modeled and

the cost of each BART alternative divided by the sum of the deciview (dv) improvement at all

impacted Class I areas. If modeling exists for Class I areas that yield impacts above 0.5 dv just

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 BARTata_

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 of less 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 of each 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 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 98lh percentile modeled value. It could be based on the 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 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 presentthe cost analyses and visibility analyses separately.

AQD LRS BART

000476
- _....!..--_... ~_.- _.,._-~_..

Basin Electric Laramie River Station

Decision Document, BART Permit Application, 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 not required to include it in the BART modeling. Additionally, the Division did

not include Savage Run in any of its 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 of Savage 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 incorrect to dismiss a control strategy on the basis that the modeled visibility

improvement is not percepti1?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 Guidelines for

Best Available 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 modeled for SCR installations aUhdim Bridger and Naughton plantsinciicate tha.t

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 other Naughton units and all

Jim Bridger units are similar. Also, environmental degradation from the operation of SCR 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 at the Jim Bridger and Naughton plants, but

the Division's BART determinations for the two plants were based on consideration of all 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 NOx emission level proposed by PacifiCorp for

Naughton Unit 3 provided less in terms of modeled visibility reductions from baseline as

compared to other units at the two 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/OFA vs. baseline was only 31%. Appendix A includes graphs of the

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 unit with the exception ofNaughton Unit 3 (104 dy). The predicted number

of dilYS 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
..._'"._. -_:~_._---,-_ .._._._-_.. ,...

'.

Basin.Electric Laramie River Station .

Decision Document, BART Permit Application, 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 that considered all five statutory factors.

11.4 NOx Controls: SCR Efficiencies - The Forest Service commented that greater SCR control

efficiencies should be factored into the cost and visibility analyses.

Response - The Division coriducted a search of the 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 NOx with a 12-month rolling average, which is significantly longer than a 3D-day.

averaging period. Because the 0.05 IblMMBtu limits are based on a 12-month averaging period,

they are not comparable to the 3D-day limits established bythe.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 of nationwide BART determinations shows that both units

outside ofWyoming for which SCR is proposed as BART will be subject to a NOx emission limit

of 0.07 IblMMBtu, and both will be based on a 3D-day averaging period.

The RBLC search showed tWo plants that will be subject to 24-hour NOx limits of less 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 of significant controls at plants

that were not designed to meet these lower levels. Based on the Division's evaluation, the

Division is satisfied that the NOx emission limit of 0.07 IblMMBtll (3D-day rolling average) that

was evaluated for SCR control under BART is the most stringent control level likely to be

achieved in a retrofit.

AQD LRS BART

000478
., .. _._-_._" -, --- ._._- ..__..._-.' ..

Basin Electric Laramie River Station

Decision Document, BART Permit Application, AP-6047

Page S of23

...... ; ',..... .':, .;:'

.;",." " :" , ' '", ," .'. ,:.,; ", • >•••- .., '.' ••·••.'i ,.;. '~', ....'

". ~~"" .:,::.. ', : ::;..,•., ;, .. :.:.·:.:!1:.E~·· ·:'.:~:~.;i~~,· ..:~t-" "":'.:;':; ; :'"

":. ..':' ·Tal)Ie.Z:;SCR'P¢bJiit.Lhnits'II"O'iiithe'RBLC .'c·",' .

, .....,- ...'; :

Facility/Location

John W. Turk Power

Plant/Arkansas

Size of NOxPermit Limit(s) for

Source Source Description SCR Control

600 MW 6,000 MMBtu!hr PC Boiler 1) 0.067Ib/MMBtu

(PRB Coal) (24-hr rolling)

2) 0.05 Ib/MMBtu

(12-month rolling)

, rSCR, BACTl

Permit

Date

Nov 2008

Note: "__" mdlcates that thIS value was not provIded In the RBLC

DryFork

Station/Wyoming

WYGEN3/Wyoming

Iatan

StationlMissouri

Big Cajun II Power

Plant/Louisiana

TSPower

P1antlNevada

OPPD -Nebraska ....

City

StationlNebraska

385MW

100MW

675MW

200MW

PC Boiler

1,300 MMBtu!hr'PC Boiler

PC Boiler

PC Boiler

PC Boiler

0.05 IblMMBtu

(12-month rolling)

rSCR, BACTl .

0.05 IblMMBtu

(12-month rolling)

[SCR,BACT]

0.08Ib/MMBtu

(30-day rolling)

[SCR,BACT]

0.07 Ib/MMBtu

(annual average)

rSCR,BACTl

0.067 IblMMBtu , (24-hour rolling)

[SCR,BACT]

O.Q7lblMMBtu

(30-day TO!ling)

rSCR,BACT]

Oct 2007

Feb 2007

Jan 2006

Aug 2005

.May 2005

Mar2005-

II.S SOLControls (Section 309) - The Forest Service understands the role of Section 309 in

exempting the State of Wyoming from making BART determinations for 802controls based on

the demonstration that the benefits from 802 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 equivalent to 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 at that time. .

Response - The State otWyoming submitted a 309 SIP as is allowed by the Regional Haze Rule.

Part of the 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 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

000479
Basin Electric Laramie River Station

Decision Document, BART Permit Application, AP-6047

Page 6 of23

m. Analysis of Comments 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 (Thunder Basin = 50-55 ppb, Jonah =

55-58 ppb). DEQ should provide an analysis of how higher ozone background concentrations

would affect results.

Response - The default ozone background 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 of the 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 for the model to use the default background of 44 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 of the stations that were used for input to 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 of approximately 40 ppb.

-The Division is confident that the default background value of 44 ppb was appropriate for the

BART modeling, and that there is no need for additional analyses to explore alternate background

concentrations.

III.2 Weight of Visibility Modeling Results in BART Determinations - EPA Region 8 commented

that DEQ should provide an explanation of how 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 important than another, because the Division looked at

all five statutory factors in their entirety. EPA guidance did not provide a quantification of the

amount of modeled visibility improvement that would be acceptable or significant. .The Division

used two metrics that were 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 Adv), to

present the results of the 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'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 CALPUFF is an appropriate applicationjor States to use jar the

particular purposes ojthis rule, to determine if an individual source is reasonably anticipated to

AQD LRS BART

000480
Basin Electric Laramie River Station

Decision Document, BART Permit Application, AP-6047

Page 7 of23

cause or contribute to impairment of visibility in -Class I areas, .and to predict the degree of

visibility improvement which could reasonably be anticipated to result from the use ofretrofit

technology f!!. an individualsource. We encourage States to use itfor these purposes." [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 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 of days above

0.5 dv predicted for a given year of meteorology was averaged with the similar result from the

other two years of meteorology. These 3-year average values were determined for each modeled

Class I area separately, and were devised to allow a straightforward, direct comparison of one'

control option to another. Regarding the sufficiency ofthe number ofmodeled 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 thai the BART conclusions and

the permit conditions 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 on the 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 of Significant Deterioration (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

000481
Basin Electric Laramie River Station ,

Decision Document, BART Permit Application, AP-604'(

Page 8 of23

process deals with retrofit controls on existing units, 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 of visibility improvement, with

predicted cumulative improvements across three Class I areas of only 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 of the Division's BART

analysis, ESP performance enhancements are already in use at the Laramie River Station.

ilL8 PM Controls: Permit Exemption - EPA Region 8 commented that Condition 5 in the 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

need for a startup 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

operating temperature and combustion offuel.oil has ceased.

Similarly for Unit 1 at Wyodak, particulates are controlled by 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 of 71 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/hr to 198 lb/hrfor thethree 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 ofthe Naughton plant, particulate controls will include a mixture ofESPs (Units 1 and

2) and a fabric 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 of S02 controls and demonstrate reasonable progress for the Class I

areas away from the Colorado Plateau.

AQD LRS BART

000482
........ \

Basin Electric Laramie River Station

Decision Document, BART Permit Application, 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 on the 20% worst days and improvement or at least no 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 at Laramie 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 of FOC at the LRS. The Division concluded

that FOe would not substantially reduce PM emissions, so FGC was eliminated from

consideration in the BART review.

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 different technologies. LNB, OFA, and a

LNB/OFA combo are all listed with the same controlled rate. Also, LNB/OFA cost is much higherfuan forPadfiCorp units, why? '.- -

Response - Computational Fluid Dynamics (CFD) modeling of the LRS boilers conducted for

Basin Electric indicated that the addition of new LNB would not be capable of reducing 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 letter to 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 of OFA

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

for the ability to stage down to a 0.90 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 and PacifiCorp 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 of the LRS

boilers by December 31,2018, and on a second LRS unit by December 31, 2023. If such a limit

is achievable at LRS, it should be required as BART. Also, greater levels oicontrol should be

examined for NOx'

AQD LRS BART

000483
,

.'

Basin Electric Laramie River Station

Decision Document, BART Permit Application, AP-6047

Page 10 of23

_........,

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

consideration of all 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 that can be achieved.

Regarding greater levels of NOx control for SCR, a letter to the Division from Basin Electric

dated September 10, 2009 states that an emission rate of 0.07 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 of an SCR between

the reheat superheater and the air heater. Thus, the spacing and the 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 of NOx' The design of an SCR is much different for a retrofit

than for a new facility. Also see response to USDA Forest Service Comment ITA.

IV. Analysis of Comments 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 cost effectiveness may be unacceptably narrow. .

.. .. 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 of the lack of historical 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 98th percentile modeled value. It could be based on

the 9801 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 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 SCR or spend more than $1,500 per ton

ofNOx removed would be contrary to EPA Appendix Y BART guidance.

Response - The EPA's Appendix Y guidance describes the EPA's selection of presumptive NOx

limits for coal-fired EGUs, and provides approximate cost levels for meeting the presumptive

limits with current combustion controls and a somewhat higher cost level for a subset of units that

would require advanced combustion controls such as rotating opposed fire air (ROFA). The EPA

guidance does not attempt to 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

000484
Basin Electric Laramie River Station

Decision Document, BART Permit Application, AP-6047

Page 11 of23

guidance also states that states may in specific cases find that the use of SCR is appropriate. As

stated previously, the Division established NO. emission limits for BART based on consideration

of all five statutory factors in their entirety, as required by the 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 for power plants greater than 750 MW.

Response - The Division followed EPA and State of Wyoming 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 other facilities.

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 be required as BART.

Response - See response to PacifiCorp comment IV.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 narrow to satisf)r Appendix Y. .

Response - The Division did n~t 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 of days 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 of days

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 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 of 24-hour periods of meteorology. 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 unit at a base-load power plant such as Jim Bridger 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
....-.... \

Basin Electric Laramie River Station

Decision Document, BART Permit Application, AP-6047

Page 12 of23

N.? General Comments: NO!.Emissions - PacifiCorp commented that emissions of NO. 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. control measures such as SCR as BART.

Response - For the 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 that the

contribution from Wyoming sources toward the formation of nitrates at the Bridger Wilderness

Area and other Class I areas warrants a full consideration of prospective 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 of perceptibility has long been disputed. Instead, the Division has

relied on EPA's Appendix Y BART guidance, which suggests a value of 0.5 dv as the level that a

'-, source "contributes" to visibility impairment. One ofthemetrics used by the Division to evaluate .,

the relative benefit of a given BART control option was the number of days yielding a modeled

impact of 0.5 dv or more.

v. .Analysis of Comments 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 BART analysis did include the combination of OFA, new LNBs, and

SCR. The performance ofthe SCR was based on inst~llation after OFAlLNB.

V.2 NOiStep 3: Evaluate Effectiveness of Remaining 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 USDA Forest 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 - Basin Electric developed cost estimates for SCR control using a combination of Coal

Utility Environmental Cost (CUECost) estimates, vendor-obtained cost data, and estimates from

AQD LRS BART

000486
Basin Electric Laramie River Station

Decision Document, BART Permit Application, 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 not preclude the use of SCR.

VA NO!...Step 4: Evaluate Impacts and Document Results (incremental costs for SCR) - The

NPS commented that the Division over-emphasized the incremental costs for the addition of SCR

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 comment V.3.

V.S NO!.Step 4: Evaluate Impacts and Document Results (basis for costs) - The NPS commented

that cost estimates' should be'documented by vendor or by the EPA Control Cost Manual.

Response - See response to NPS comment V.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) of a source.

Response - See response to USDA Forest Service comment 11.1.

V.7 - -- NO!.Step 5: Visibility Improvement DeteJ!mination fincJ!emental benefits of SCR)..-.The NJ>S

commented that the Division placed too much emphasis on the incremental improvement in

visibility that was predicted for the addition of SCR. The total predicted visibilitY improvement

resulting from a combination of control options should have been presented.

Response - The incremental improvement in modeled visibility with the addition of SCR was

mentioned prominently in the summary of the Division's BART conclusions, but all visibility

modeling results were considered. For'more information on the presentation of the 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 that the Division should use

$/dv as an additional metric for evaluating BART controls.

Response - See response to PacifiCorp response IV.l.

V.9 BART Conclusions for N0,LControls: Cost Benchmarks - The NPS commented that the

Division determined that the costs for SCR were reasonable, yet rejected SCR for BART control.

DEQ should explain why and provide 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 of control costs that were reasonable.

AQD LRS BART

000487
·~''''''''

Basin Electric Laramie River Station

Decision Document, BART Permit Application, 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.

Recent PSD 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 of ammonia, why would this be a particular problem

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 of compliance. Potential energy losses and environmental impacts from

the operation of SNCR and SCR were m~ntioned in the Division's BART analysis, but were only

part ofthe larger evaluation that considered 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" of fly ash. Evidence should be

presented and the economic impact quantified. The NPS also commented that the Division stated

that SCR could create "blue plume" if the ammonia injection rate is not well conirolled. NPS

states that it assumes that a plant operator can properly control the injection rate.

Response - See response to NPS comment V.lO.

V.12 BART Conclusions for PMlllControls: 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 have recently been approved for fabric filters (e.g., Desert Rock Project).

Response - See response to EPA Region 8 comment III.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) of the 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 improvement with the BART controls chosen by the 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 not have changed the determinations.

AQD LRS BART

000488
- ~"""

Basin Electric Laramie River Station

Decision Document, BART Permit Application, AP-6047

Page 15 of23

VI. Analysis of Comments from the Powder River Basin Resource Council:

VI. 1 SCR as BART - The Powder River Basin Resource Council commented that SCR is the best

available retrofit technology and should be required as BART at all ofthe Wyoming power plants

under consideration.

Response - The Division determined BART for the control of NOx emissions from power plants

in Wyoming based on a full consideration of all 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 control technology with the highest level of control in all cases. "

VIT. Analysis of Comments from the Powder River Basin 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 of a given source should be modeled for visibility impacts.

Response - See response to USDA Forest Service comment n.l.

VII.2 SCR as BART - The Powder River Basin Resource Council, et aJ. commented that SCR is

BART and must be required for all units at all coal-fired power plants.

Response - See response to USDA Forest Service comments and II.3.

VIIJ Section 309 Milestone Program - The Powder River Basin 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 BART limits.

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 of the

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 comment II.S and EPA 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

000489
Basin Electric Laramie River Station

Decision Document, BART Permit Application, AP-6047

Page 16 of23

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 of Wyoming's

Visibility .SIP and visibility regulations to address reasonably attributable visibility impairment,

neither the Federal Land Managers of any Class I area nor the Division has certified that visibility

impairment, attributable to a source or small group of sources, exists in any Wyoming Class I

area pursuant to provisions in Chapter 9, Section 2 ofthe WAQSR. The provisions ofChapter 9,

Section 2 ofthe WAQSR are therefore not relevant to 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) meet presumptive BART, but further reductions are warranted to reduce Class I

impacts. The Division will require SCR to 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 NOx control 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 of LNB with OFA as

-- well as why SCR was 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 without modification. 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 of Comments 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/or BARTDeterminations Under the Regional Haze Rule [Appendix Y to part

51]

• Chapter 6, Section 9 ofthe Wyoming Air Quality Standards and Regulations (WAQSR),

BestAvailable Retrofit Technology

AQD LRS BART

000490
Basin Electric Laramie River Station

Decision Document, BART Permit Application, AP~6047

Page 17 of23

VIII.2 Regional Haze Rule - The Sierra Club commented that the State ofWyoming can and should do

more to 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 associated with the Long-Term Strategy for regional haze.

VIII.3 Control of Nitrogen Oxide Emissions - The Sierra Club commented that the State ofWyoming

should require the coal plants to install devices that reduce nitrogen oxide emissions.

Response - All ofthe Division's BART determinations for coal-fired power plants in the 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 reIief for citizens or for the health of forests and the

environment.

Response - The Division's BART determinations and other requirements under the regional haze

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·

potential NO. emissions of approximately 13,500 tons per year.

VIII.5 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 of air pollution, 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 of the power plants with an alternate source of

energy is well beyond the scope ofthe BART program.

VIII.6 Pollution Reduction from Power Plants - 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 air pollution is minimized. .

Response - The Division determined BART controls based on the five statuto!)' factors

developed by the 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
_ .....

Basin Electric Laramie River Station

Decision Document, BART Permit Application, AP-6047

Page 18 of23

VIII.7 SCR Controls - Several commenters stated that BART for NOx control should be SCR for all

plants.

Response - See responses 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 - See responses to USDA Forest Service comments II.3 .

.X. Analysis of Comments from Basin Electric Power Cooperative:

X.1 Permit Condition 16 - Basin Electric requested that the Division revise BART Permit Condition

16 for the LRS to change the time for submitting a permit application for additional add-on NOx

control from six years prior to installation to two years prior to installation.

Response - The Division will make the requested change in the final BART permit for the 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 Basin Electric, 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 in the Division's analysis will be included

in the permit with the 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 of the Wyoming §308 Regional Haze

State Implementation Plan. It shall include an analysis of the 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 unit by December 31; 2023. .

Dated this 31st day ofDecember, 2009.

Administrator

Da~det~ Wyoming Air Quality DivisionJj~J/2v- Jo . Corra

D ctor

Wyoming Dep1,lrtment ofEnvironmental Quality

AQD LRS BART

000492
--_._- -- - --- ---_.--_._--_._- '-----_.._--" ---- --._--_. __._-----------_._--_ -._.- -----_.._ _-_. __.._ __._----_._.__ _.__.._--_._.._--- .._.__ __._- --_._._._-----_. -_.- _.---_. ----_._- _. _.-_.-._,. - _ _-

'.

.APPENDIX A

VISIBILITY MODELING RESULTS (Baseline vs. LNB and SCR)

AQD LRS BART

000493
Figure 1

Modeled BART Impacts in Bridger Wilderness Area

Naughton and Jim BridgerPowei Plants: 98th Percentile (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 (530 MWj

• LNBjOFA

III LNBjOFA + SCR

2.500 "TI-------------------------'---------------------------

/ ./

(Modeling results represent the 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 U4
Figure 2

Modeled BART Impacts in Wind Cave National Park

Wyodak, Dave Johnston, and Laramie River ~tation Power Plants: 98th Percentile (delta-dv)

.....'

LRSU1 LRS U2 LRS U3

LRS Ul=Laramie River Station Unit 1 (550 MW)

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

LRS U3 =Laramie River ptation Unit 3 (550 MW)

Wyodak =335 MW

DJ U3 = Dave Johnston Unit 3 (230 MW)

OJ U4=Dave Johnston Unit 4 (330 MW)

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

0.500

1.000

0,000

Wyodak OJ U3 OJ U4

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

>-

"9

Qj

e.

0»00

~O<Or

01;0

en

llJ

»

;0

-I
Figure 3

Modeled BART Impacts in Bridger Wilderness Area

Naughton and Jim Bridger Power Plants: # 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:'~~

~f~_ r"L II P !ij',~ . ~; ;~

~~11 ~~ ."".11 ~i 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 U4
Figure 4

Modeled BART Impacts in Wind Cave National Park

Wyodak, Dave Johnston, and Laramie River Station Power Plants: # Days> 0.5 deIta-dv

Wyodak=335 MW

DJ U3 = Dave Johnston Unit 3 (230 MW)

DJ U4 =Dave Johnston Unit 4 (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 represent the three-year average using 2001-2003 meteorology)

LRS U1 LRS U2 LRS U3