### NewMexico 

### ENVIRONMENTDEPARTMENT 

## AirQualityBureau 1301 SilerRoad, Building B SantaFe, NM 87507 BILLRICHARDSON Governor Phone (505) 476-4300 RON CURRY Secretary
DIANEDENISH Lieutenant Governor Fax (505)476-4375 www.nmenv.state.nm.us JON GOLDSTEIN Deputy Secretary

October 27, 2009
Ms. AnitaLee (Air-3) U.S. Environmental ProtectionAgency (EPA) Region IX 

# RECE'VED 75 Hawthorne Street SanFrancisco, CA94105-3901 

### NOV 0 9 2009 Permits urticeAir-3 Re: EPA-R09-0AR-2009-o598 U.S. EPA. Region 9
DearMs. Lee,
The Air Quality Bureau of the New Mexico Environment Department (NMED) appreciates the opportunityto comment onthe U.S. Environmental ProtectionAgency's (EPA)Advanced Notice ofProposed Rulemaking (ANPR) for the Assessment ofAnticipated Visibility Improvements at Surrounding Class I Areas and Cost Effectiveness of Best Available Retrofit Technology (BART)forFourComers PowerPlant (FCPP) and Navajo Generating Station (NGS). According to the ANPR, based on 2006 emissions data from the EPA Clean Air Markets Division, FCPP is the largest source ofNOx emissions in the United States (nearly 45,000 tons per year (tpy) of NOx). The FCPP is located near the Four Comers region of Arizona, New Mexico, Utah, and Colorado, and is within 300 kilometers (km) of sixteen mandatory Class I areas: Arches National Park (NP), Bandelier Wilderness Area (WA), Black Canyon of the Gunnison WA, Canyonlands NP, Capitol Reef NP, Grand Canyon NP, Great Sand Dunes WA, La Garita WA, Maroon Bells-Snowmass WA, Mesa Verde NP, Pecos WA, Petrified Forest NP, SanPedroParks WA, WestElkWA, WeminucheWA, and WheelerPeakWA.
Also according to the ANPR and based onthe samedatabase, NGS is the fourth largest source of NOx emissions in the United States (nearly 35,000 tpy). NGS, in northern Arizona, is located within 300 km ofeleven Class I areas: Arches NP, Bryce Canyon NP, Canyonlands NP, Capitol ReefNP, Grand CanyonNP, Mazatzal WA, MesaVerdeNP, Petrified ForestNP, PineMountain WA, Sycamore CanyonWA, andZion NP.
The determinations of BART at the FCPP and the NGS are very important decisions that will affect air quality at alargenumberofClass I areas. TheNMEDhas received frequent complaintsMs. Anita Lee October 27, 2009 Page 2
about the brownish 

### NOx plume from FCPP which is very visible in the FourComers area. This plume is often visible from Mesa Verde National Park, located approximately 70 miles from the FCPP. As provided for in 40 CPR §51.308(e)(I)(ii)(B), the determination ofBART for fossil-fuel fired power plants having a total generating capacity greater than 750 megawatts must be made pursuant to the Guidelines in Appendix Y ofPart 51. Due to the size ofthe FCPP and the NGS, the EPA must follow the Guidelines in making BART determinations for the BART-eligible sources atbothplants. The NMED is concerned that theEPAmayhave underestimated the emissions reduction possible from selective catalyticreduction (SCR) installation on Units 1-5 atFCPP. Appendix Y provides guidance on how to evaluate control techniques with a wide range of emission performance levels. Specifically, Appendix Yprovides that: [I]in analyzing the technology you take into account the most stringent emission control level that the technology is capable of achieving. You should consider recent regulatory decisions and performance data (e.g., manufacturer's data, engineering estimates and the experience ofother sources) when identifying an emissions performance level or levels to evaluate. (Emphasis added)
The EPA cites the Arizona Department of Environmental Quality's recent determination that 75% control from SCR (following upstream reductions by low NOxburners) was appropriate for the Coronado Generating Station in Arizona. TheNOx emissionrate at the Coronado Generating Station is 0.080 pounds per million British thermal units (lb/mmBtu) on a 30-Day Rolling Average. This rate was the result of a settlement agreement between the EPA and the Department ofJustice and the Salt River ProjectAgricultural Improvement and PowerDistrictto resolve Clean Air Act violations at the Coronado Generating Station. As such, it represents a negotiated emissions reduction rather than the maximum emissions reduction achievable from SCR controls. It is therefore not necessarily the appropriate starting point for a BART determination.
The ANPR does not provide sufficient detail on how the NOx emission rate for the Coronado Generating Station was achieved; therefore, the NMED cannot determine whether or not the rate is appropriate for the retrofit SCR installation at the FCPP. Ifthe NOx emissionrate submitted in the BART analysis for the FCPP was based on a vendor guarantee, the NMED believes that the BART Guidelines require that EPA use the vendor's guaranteed rate unless it is demonstrated thattherate is not achievable. The NMED also encourages additional review ofthe particulate matter controls at Units 4 and 5 at the FCPP. It appears that because these units are already controlled by baghouses, no additional BART review was conducted on additional control technology on these units. This contradicts the BART Guidelines, which state that for units subject to a BART review that have control measures or devices already in place, it is important to include control options thatMs. AnitaLee October 27, 2009 Page 3
involve improvements to existing controls and not to limit the control options only to those measures that involve a complete replacement ofcontrol devices. Additional or more effective control technology on these units, as well as additional improved control technology on Units I through 3 at the FCPP and Units I through 3 at the NGS could achieve additional visibility improvements at mandatory Class I areas. Doing so would also achieve the co-benefit of additional mercury reductions.
The NMED agrees with EPA that the estimated total annual cost of the NOx and particulate matter (PM) control technologies should be adjusted based on an annual-to-capital cost ratio of 15%, to be consistent with annual costs estimatedby otherfacilities. Regarding the modifications to emission rate inputs at the FCPP, the NMED considers it reasonable that EPA used the NOx emission data for the highest emitting days that occurred in 2001. The NMED also believes it is reasonable to use sulfur dioxide (SOz) emission data (reduced with an 88% control efficiency) from a more recent period (2006

- 2007), rather than using the SOz data from the 2001

- 2003 meteorological periods. The modified SOz inputs appear reasonable to the NMED because the controlled SOz emission rates more accurately reflectthe facility's currentcontrol technology. Regarding the inclusion ofhydrochloric acid (HCI) and hydrogen fluoride (HF) in PM modeling, the EPA'smethod ofincluding these pollutants is more reasonable than ArizonaPublic Service's (APS) assumption that sulfuric acid (Hz S04) is the only contributor to condensable inorganic PM. However, it is likely that the inclusion doesn't make a substantial difference in visibility modeling results. This is because the impact ofthe pollutants is relatively small in comparison with other condensable inorganic PM, including nitrate and sulfate. Additionally, as EPA notes, the amount ofHCI and HF is less than 0.01% by mass and such a small amount has a negligible impactin degrading visibility in Class I Areas.
The NMED supports a rigorous application of the BART Guidelines to select retrofit technologies that are truly the "best available," and to set emission limits that are clear, federally enforceable, and legally defensible. We appreciate your consideration ofthe above comments as part oftheEPARegion9'sreview ofBART for the FCPP and NGS. Sincerely,

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\ MaryUhl Bureau Chief Air Quality Bureau