30 em july 2005 awma.org

emfeature

Proposed coal-fired electric-generationprojects in the eastern United States must adopt creativeapproaches to mitigate future and existing adverse impactson designated Class I areas. Class I areas (e.g., wildernessareas and national parks) are classified by Congress as thoseareas that are areas afforded the least deterioration in airquality. These projects face a unique situation in that theregion’s abundant reserves of high-sulfur coal are generallylocated in or adjacent to states with several Class I areas.Projects that choose to locate close to the coal reserves, tominimize fuel transportation costs and thus make the project

more financially viable, are faced with being located withinthe modeling range of several Class I areas. The proposedLongview Power Project is one such project. Located nearMorgantown, WV, it is adjacent to several coal reserves andwithin 300 km of four Class I areas: Dolly Sods Wilderness,Otter Creek Wilderness, James River Face Wilderness, andShenandoah National Park.

One approach for improving air quality in Class I areasthat is gaining attention and proving to be effective is the

implementation of emissions cap-and-trade programs. Ex-amples of successful trading programs include the acid rainprogram and the nitrogen oxides (NOx) budget program.More recently, the U.S. Environmental Protection Agency(EPA) proposed a cap-and-trade program as an alternativeto the current nitrogen dioxide (NO2) Prevention of Sig-nificant Deterioration (PSD) increment for attainment inunclassified and Class I areas (70 FR 8880; February 23,2005). This article describes a similar approach for aciddeposition and visibility impacts from the proposed LongviewPower Project in four Class I areas. Part I discusses the airquality impacts of the proposed project. Part II (to be pub-lished in next month’s EM) discusses the mitigation plandeveloped to reconcile the gap between generally acceptableemissions limits and the predicted adverse visibility and aciddeposition impacts on Class I areas.

PERMITTING REQUIREMENTSThe proposed Longview Power Project is a 600-MW coal-fired power plant to be located in Maidsville, WV, nearMorgantown. The plant’s design features a pulverized coal

Louis M. Militana, QEP, is managing partner with AAQSInc. in Lincoln University, PA; Cindy Huber is an air

resource specialist with the U.S. Department of Agriculture,Forest Service; Christopher Colbert is vice president of coal

development with GenPower; Chris Arrington is an airquality modeler with the West Virginia Department of

Environmental Protection, Division of Air Quality; andDon Shepherd is an environmental engineer with the U.S.

Department of Interior, National Park Service.E-mail: lmilitana@aaqsinc.com.

The Longview Power Project’s

selected BACT produced

compliance with all air quality

impacts, except for Class I

visibility and acid deposition.

Copyright 2005 Air & Waste Management Association

awma.org july 2005 em 31

(PC) supercritical boiler with a once-through, balanced-draft,single reheat steam turbine/generator burning 2.5% sulfur(nominal) bituminous coal. The project began thepreconstruction air quality permitting process in February2003 with the submittal of a PSD permit application to WestVirginia Department of Environmental Protection(WVDEP). The permit application contained a Best Avail-able Control Technology (BACT) demonstration and a dem-onstration of compliance with all air quality impacts (i.e.,National Ambient Air Quality Standards [NAAQS] and PSDincrements), except for Class I visibility and acid deposition.The project’s predicted sulfur dioxide (SO2) emissionsshowed potential impacts well above the Federal Land Man-agers’ (FLM) thresholds for visibility and acid deposition.

Under the PSD preconstruction permitting regulations,BACT applies to major new sources or major modificationsto existing sources located in attainment areas that result ina significant increase of regulated pollutant emissions. TheLongview Power Project triggered PSD review because (a)the project area is in attainment or not classifiable for allcriteria pollutants, (b) the plant is listed as a 100 t/yr majorstationary source under 40 CFR 52.21, and (c) its potentialto emit (at least) one criteria pollutant is greater than 100t/yr. Consequently, the project’s developers were required

to prepare and submit a PSD permit application to WVDEP(the local permitting agency), including BACT and air qual-ity impact analyses for Class I and Class II areas. Each ofthese is discussed below. The PSD permitting regulationsprovide for a system of area classifications, which affordsstates an opportunity to identify local land use goals. Class Iareas are allowed only a small degree of air quality deterio-ration, while Class II areas can accommodate normal well-managed industrial growth.

BACT ANALYSISThe BACT analysis for the Longview Power Project followedEPA’s “top-down” approach, outlined in its Draft New SourceReview Workshop Manual.1 BACT determinations were con-ducted for emissions of SO2, particulate matter (PM), PMless than or equal to 10 micron (PM10), carbon monoxide(CO), NOx, volatile organic compounds (VOCs), sulfuricacid (H2SO4), and beryllium (Be). BACT determinationsare case-by-case analyses that involve an assessment of theavailability of applicable technologies capable of sufficientlyreducing the emissions of a specific pollutant, as well as theeconomic, energy, and environmental impacts of each tech-nology. The results of the initial BACT analysis for the LongviewPower Project and a comparison of the BACT emissions limits

Figure 1. Location of Class I areas.

Copyright 2005 Air & Waste Management Association

32 em july 2005 awma.org

to the permits limits of other recent and comparable projectsare shown in Tables 1 and 2, respectively. The initial BACTemissions limits were used in the air quality impact analysisfor Class I areas. This is discussed below.

AIR QUALITY IMPACT ANALYSISAn assessment of potential adverse impacts on visibility andother air quality-related values in Class I areas is required byall PSD applicants. Air quality impacts at Class I areas mustbe assessed under PSD regulations if they are within 100 kmof the source or if the source is judged to have a potentialadverse impact on Class I areas at distances over 100 km.Four Class I areas are located within 300 km of the proposedLongview Power Project site: Dolly Sods Wilderness (91 kmsoutheast), Otter Creek Wilderness (78 km south-southeast),James River Face Wilderness (237 south-southeast), andShenandoah National Park (173 km southeast). Figure 1shows the locations of the Class I areas relative to the pro-posed project site. The model used in the Class I area airquality modeling analysis was the EPA-approved air disper-sion model, CALPUFF. The procedures used in conductingthe modeling analysis followed the requirements outlined inEPA Guideline on Air Quality Models;2 Federal Land Managers’ Air

Figure 2. Modeling domain boundaries.

Quality Related Values Workgroup (FLAG), Phase I Report;3 Inter-agency Workgroup on Air Quality Modeling, Phase 2 Report;4 andguidance provided by the West Virginia Division of AirQuality and FLM. Brief descriptions of the selected air qualitymodel, input data, and modeling procedures are presentedin the following sections.

Air Quality ModelThe CALPUFF air dispersion modeling system, which in-cludes CALMET and CALPOST,5 was used to predict airquality impacts at the four Class I areas. CALPUFF is a mul-tilayered, non-steady-state puff dispersion model and is rou-tinely used to evaluate long-range transport and Class I areaimpacts. The CALMET program generates the three-dimen-sional meteorological data used by CALPUFF, while theCALPOST program processes the CALPUFF model outputsand calculates the visibility impacts, concentration levels, anddeposition amounts. CALPUFF was used with the defaultdispersion settings contained in the Phase 2 Report.4 Themodel was also used in a refined mode in a manner that isconsistent with the guidance,3,4 except that it was agreed thatonly one year of meteorological data would be sufficient foranalysis in this case.

Copyright 2005 Air & Waste Management Association

awma.org july 2005 em 33

Receptor GridThe CALPUFF receptor grid com-prised multiple air quality modelingreceptors located at 500-m intervalswithin the Dolly Sods, Otter Creek,and James River Face Class I areas,and at 1000-m intervals withinShenandoah National Park. Theelevation for each receptor was deter-mined by selecting the maximum el-evation falling within the area,extending halfway to the neighboringreceptors. U.S. Geological Surveydigital elevation model data (90-mspacing) and a geographical informa-tion system were used to determinethe maximum elevation for each re-ceptor. A total of 129 receptors wereused for Dolly Sods, 305 for OtterCreek, 132 for James River Face, and840 for Shenandoah National Park.

Meteorological DataCALPUFF requires an extensive arrayof meteorological data to successfullyperform its dispersion modeling calculations. Multiplemeteorological data sources were used for this analysis,including Four Dimensional Data Assimilation (FDDA)—Mesoscale Meteorological (MM) data, representative Na-tional Weather Service (NWS) data, and Clean Air Status

and Trends Network (CASTNET) data. One year’s worth ofMesoscale Meteorological Model 5 (MM5) 36-km grid data(1996), in combination with all concurrent NWS andCASTNET meteorological data (both surface and upper airstations) within the modeling domain, were used as input

Table 1. Summary of initial BACT determination for the Longview PowerProject.

Emissions Limit /Pollutant Averaging Period BACT

SO2 0.15 lb/MMBTU / 3-hr Wet FGDaverage 0.12 lb/MMBtu /24-hr average

PM/PM10 0.018 lb/MMBtu / Baghouse(Total – 6-hr averagefilterable andcondensable)CO 0.11 lb/MMBtu / Proper boiler design and good combustion practice

3-hr averageNOx 0.08 lb/MMBtu / Dry low-NOx burners with SCR

24-hr averageVOC 0.004 lb/MMBtu / Proper boiler design and good combustion practice

3-hr averageH2SO4 0.0075 lb/MMBtu / DSI/baghouse

24-hr averageBe and As ≥ 99% control DSI/baghouseHg ≥ 80% control SCR and DSI/baghouse and WFGDHCl, HF ≥ 99% control DSI/baghouse and WFGDBenzene NA Proper boiler design and good combustion practice

NA = Not applicable; WFGD = wet flue gas desulfurization; SCR = selective catalytic reduction; DSI = dry sorbent injection.

Table 2. Comparison of the Longview Power Project’s emissions limits to other recent PSD permits.

SO2 PM NOx Emissions Emission Emissions

Facility Name/Location Boiler Capacity Limits Control Limits Control Limits ControlType (MW) (lb/MMBtu) Type (lb/MMBtu) Type (lb/MMBtu) Type

Longview Power Project, WV PC 600 0.12 WFGD 0.018 FF 0.08 SCRBlack Hills Power-Wygen, WY PC 500 0.15 DFGD 0.018 FF 0.09 LNB/SCRBull Mountain-Roundup, MT PC 390 0.12 DFGD 0.015 FF 0.07 LNB/SCRKansas City P&L-Hawthorne, KC PC 570 0.12 DFGD 0.018 FF 0.08 SCRLS Power-Five Forks Energy, VA PC 2x800 0.145 WFGD 0.018 FF 0.10 SCRLS Power-Plum Point Energy, AR PC 2x800 0.16 DFGD 0.018 FF 0.10 SCRMustang, NM PC 300 0.14 CDS 0.018 FF 0.09 SCRN. American Power-Mid PRB, NM PC 1x500 0.18 DFGD 0.018 FF 0.091 SCRPrairie State Gen, IL PC 2x750 0.18 WFGD 0.018 WFGD/ 0.09 LNB/SCR

WESPRocky Mountain Power-Hardin, MT PC 113 0.15 WFGD 0.015 WFGD 0.09 SCRSantee Cooper Cross 3&4, SC PC 2x600 0.30 WFGD 0.018 FF 0.07 SCRThoroughbred, KY PC 2x750 0.17 WFGD 0.018 WFGD/ 0.09 SCR

WESPTucson Electric Power, AZ PC 2x380 0.60 DFGD 0.015 NA 0.15 NATwo Elk #2, WY PC 1x500 0.18 DFGD 0.018 FF 0.091 SCRRawhide PC 285 0.103 DFGD NA NA NA NABonanza PC 400 0.095 WFGD NA NA NA NAInterMountain W-DB-PC 950 0.10 WFGD 0.024 FF 0.07 LNB/SCRSTEAG-Desert Rock PC 1500 0.06 WFDG 0.020 FF 0.06 SCR

NA = Not applicable; PC = pulverized coal; WFGD = wet flue gas desulfurization; DFGD = dry flue gas desulfurization; W-DB-PC = WFGD, dry bottom, pulverized coal; WFGD/WESP = WFGD with wet electrostatic precipitator; CDS = circulating dry scrubber; FF = fabric filter; SCR = selective catalytic reduction; LNB/SCR = low-NOx burners with SCR.

Copyright 2005 Air & Waste Management Association

34 em july 2005 awma.org

Table 3. PSD increment analysis for the Longview Power Project.

Maximum Predicted Air Quality Concentration (µg/m3)James River Shenandoah Significance PSD

Pollutant Otter Creek Dolly Sods Face National Park Level IncrementSO23-hr 3.38 2.28 4.10E-01 1.39 1.0 25

24-hr 0.91 0.719 0.195 0.486 0.2 5

Annual 0.0358 0.0446 0.0519 0.0239 0.1 2

PM1024-hr 0.0569 0.0441 0.0107 0.0338 0.3 8

Annual 0.00236 0.00272 0.000258 0.00125 0.2 4

NO2Annual 0.0189 0.0221 0.00183 0.00983 0.1 2.5

Table 4. Visibility analysis for the Longview Power Project.

Change in 24-hr –β extinctionJames River Shenandoah Visibility

Otter Creek Dolly Sods Face National Park Threshold

Max Change (%) 14.47 13.73 5.27 11.69 5 – 10

No. of Days > 5% 12 20 1 13 NA

No. of Days >10% 6 3 0 1 NA

NA = Not applicable.

Table 5. Deposition analysis for the Longview Power Project.

Maximum Deposition (kg/ha/yr)Deposition

Shenandoah AnalysisOtter Creek Dolly Sods James River Face National Park Threshold

S 0.03 0.04 0.01 0.02 0.01

N 0.01 0.01 0.002 0.006 0.01

for CALMET. The CALMET program also requires a bound-ary to the modeling domain, grid cell size, and the numberof layers for the meteorological variables. The boundariesof the domain were developed following the guidance inthe Phase 2 Report,4 including extending the domain 50 kmbeyond the outer receptors and the project site. The bound-aries are shown in Figure 2.

Class I ImpactsThe CALPOST program wasused to determine the PSDincrement consumption,changes in visibility, and depo-sition of nitrogen (N) andsulfur (S) compounds for thereceptors in the Class I areas.The guidance outlined in thePhase I Report 3 was used to de-termine background levels forvisibility and natural condi-tions were used as referencelevels. The predicted changesin the reference levels due to emissions from the proposedproject were calculated. Initially, the value for maximumrelative humidity (RHMAX) was set at 98% to cap therelative humidity adjustment factor [f(RH)] used to cal-culate the change in extinction. The measurement ofvisibility degradation is the extinction of light in theatmosphere. The change in extinction is calculated toevaluate the potential impact a source may have on cur-rent or natural background visibility conditions. Additional

modeling was per-formed using avalue of 95% forRHMAX. All S andN species were in-cluded in CALPOSTto evaluate aciddeposition, whichwas calculated inunits of kg/ha/yr.

PSD Increment.The CALPUFFmodel was used topredict ambient airconcentrations for

the Class I areas. The peak short- and long-term averageconcentrations of SO2, PM10, and NO2 are summarized inTable 3. These results indicate that BACT emissions fromthe project will not cause an exceedance of the Class Iincrements for SO2, PM10, and NO2, and in fact, the pre-dicted impacts were below the Class I significance levelsfor NO2 and PM10. Class I significance levels are pollutantand averaging specific air quality concentrations below

which it has been determined that a source cannot causeor significantly contribute to a model predictedexceedance of a NAAQS and/or a PSD increment.

Visibility. The predicted change in visibility for the ClassI areas are presented in Table 4. The predicted change invisibility (from natural background levels) are comparedto thresholds of 5% and 10% change in extinction toevaluate the impact of the proposed project on visibility

in the Class I areas. As shownin Table 4, the project’s esti-mated BACT emissions werepredicted to cause anexceedance of the 5% changein extinction threshold levelfor 13 days per year inShenandoah National Park,12 days in Otter Creek, and20 days in Dolly Sods. Anexceedance of 1 day per year

Copyright 2005 Air & Waste Management Association

awma.org july 2005 em 35

was determined for JamesRiver Face. It was predictedthat the 10% change in ex-tinction threshold level wasexceeded for a total of 10days per year among allfour Class I areas. A changein extinction greater than10% was predicted to occurfor 6 days per year in OtterCreek, 3 days in Dolly Sods,and 1 day in ShenandoahNational Park. There wereno days predicted with achange in extinction

greater than 10% in the James River Face area. The maxi-mum predicted change in extinction due to project emis-sions was 14.5%, which was predicted for Otter Creek(located closest to the project site).

Deposition. The CALPUFF model was used to predictthe annual wet, dry, and total deposition amounts for Sand N compounds. Deposition analysis thresholds (DATs)for S and N in Class I areas established by the NationalPark Service were used in this assessment. For easternClass I areas, the DATs for both S and N are 0.01 kg/ha/yr. Predicted deposition amounts lower than these thresh-olds are considered unlikely to cause adverse impacts inClass I areas. The total N deposition amount was calcu-lated by determining the wet and dry nitrate and nitricacid deposition and dry NO2 deposition amounts and mul-tiplying each component by the ratio of the individualmolecular weight to the molecular weight of N. A simi-lar methodology was used for the S deposition calcula-tions. The maximum S and N deposition amounts areshown in Table 5. The total S deposition was predictedto be between three and four times the DAT; while thetotal N deposition was predicted to be the same or lessthan the DAT.

In summary, the estimated BACT emissions limits forthe proposed Longview Power Project showed adverse im-pacts on Class I areas that were three to four times theacceptable S deposition levels and three times the visibil-ity threshold, but were well below the PSD Class I incre-ments and below the Class I significance levels for NOxand PM10.

MITIGATION PLANOnce the analysis was complete, a mitigation plan was pro-posed to reconcile the gap between BACT emissions lim-its and predicted S deposition and visibility impacts. Themitigation plan is described in Part II of this article, whichwill be published in the August 2005 issue of EM.

ACKNOWLEDGMENTSThe authors thank Robert Karpovich of AAQS Inc. forthe air quality modeling analysis and graphical supportfor this article.

REFERENCES1. Draft New Source Review Workshop

Manual; U.S. Environmental Pro-tection Agency (EPA): Washington,DC, 1990.

2. Guideline on Air Quality Models; 40CFR Part 51 Appendix W, 2003.

3. Federal Land Managers’ Air QualityRelated Values Workgroup, Phase I Re-port; U.S. Forest Service: Washing-ton, DC, December 2000.

4. Interagency Workgroup on Air QualityModeling, Phase 2 Report; U.S. Envi-ronmental Protection Agency(EPA): Washington, DC, 1998.

5. A User’s Guide for the CALPUFF Dis-persion Model; Earth Tech Inc.: LongBeach, CA, 2000.

em

Diesel Exhaust Partnering with Stakeholders

to Reduce Emissions

October 6-7, 2005, Oak Brook, IL

In the last 15 years, air quality agencies have increasingly

focused on the regulation of diesel emissions. In that

time, diesel engine emissions and technology have

significantly improved. Yet, further advances will be

necessary to attain the 2007 standards announced by

the U.S. Environmental Protection Agency and the

California Air Resources Board. This conference will

provide an overview of the following developments

in the regulatory, policy, and scientific arenas:

• New 2007 emissions standards

• Government programs that affect the industry

• New perspectives on health issues related to old diesel technology

• Evaluating new diesel exhaust technology

Visit www.awma.org for more information.

Copyright 2005 Air & Waste Management Association