SALT RIVER PROJECT P . O. Box 5 2025 Phoenix , A Z 850 7 2
-2025 ( 60

2 ) 236
- 5262 F ax (602) 236
- 6690 Kelly B arr @ srpnet .com July 20, 2012 Ms. Deborah Jordan Director, Air Division, Region 9 United States Environmental Protection Agency 75 Hawthorne Street San Francisco, CA, 94105 Re: SNCR Demonstration Test Navajo Generating Station Dear Ms. Jordan: KELLYJ. BARR , ESQ. Senior D irector Environment a l Managem en t , Po l ic

y a nd Compliance

As you are aware , Salt River Project Agricultural Improvement and Po w er District (SRP) rec entl y comp let e d a Demonstration Te s t for Selective Non-Catalytic Reduction (SNCR) at Navajo Generating Station (NGS). The test was conducted to provide supplemental information t o the updated Best Available Retrofit Technology (BART) analysis that was submitted to the U . S. Environmental Protection Agency (EPA) in January 2012. The purpose of this l etter i s to summarize the results of the Demon stration Test and to provide a recommendation regarding a potential permit limit that would be achievable at NGS using this techno l ogy . Th e Demonstration Test was conducted on Unit 3 at NGS during a three-week period i n M ay 2012. It is important to note that a minor overhaul that had just been completed on this unit included maintenance activities on the Low-NOx Burners. Between overhauls, emis sion s reduction performance will degrade due to normal equipment wear-and-tear. Th is trend ha s been consistently observed with the Low-NOx Burners at NGS. Therefore , the resu lts obta i ned in the Demonstration Test most likely represent the best possible performance that SNCR co u ld achieve at NGS. The test demonstrated that the addition of SNCR consistently reduced baseline nitrogen o xide {NOx ) emission by approximately 20% without any noticeable impact on plant operations . The test was conducted using varying amounts of urea reagent. Table 1 contain s the test re sults that are most relevant to establishing a NOx permit limit for SNCR at NGS .Ms. Deborah Jo rdan Jul y 20, 2012 Page Two Table 1. Summary of SNCR Demonstration Test Results for Unit 3 Parameter Test Condition #1 Test Condition #2 Unit Load- Net (MW) 750 750 Baseline NOx (lb/MMBtu) 0 . 22 0.21 Controlled NOx (lb/MMBtu) 0.16 0 . 17 Ammonia Slip (ppm) 3 . 1 0.4 Although actual stack emissions generally fell within the range repre sented in the January 2012 BART report (0 . 15-0.18 lb/MMBtu), values measured at the lo w er end of the range re sulted in higher than expected ammonia slip . Considering the tradeoff betw een NOx reduction and ammonia slip , and that a sufficient operating margin i s necessary for compliance , SRP believes that a NOx pe rmit limit of 0.20 lb/MMBtu would be achievable u sing SNCR at NGS . SRP continue s to strongly believe that Low-NOx Burners and Sepa rated Overfire Air is the mo s t cost-effective control option for NGS, and a BART proposal that i s ba sed on th is techno l ogy w ould not introduce the risk of broader adverse economic conseque n ce s . We appreciate EPA's review and con sideration of this information . If you have any qu estion s regarding the content of this letter, please feel free to contact me at 602-236-5262 . Sincerely,
Kelly J. Barr