February 29, 2012

Memorandum to the North Dakota Regional Haze File Docket ID # EPA-R08-OAR-2010-0406

Subject: Supporting Material for the North Dakota R egional Haze FIP Concerning

Selective Non Catalytic Reduction (SNCR) and Ammoni a Slip Mitigation for Lignite Fly Ash at Great River Energy’s (GRE) C oal Creek Station

From: EC/R, Inc.

Issue: The ability of SNCR systems to operate in an ammoni a slip controlled condition.

Summary: On February 21, 2012, Doug Grano of EC/R received a n e-mail from Bill Cummings of Fuel Tech, Inc. concerning ammonia slip from SNCR systems. Mr. Cummings stated that all Fuel Tech SNCR systems are capable of operating in a slip controlled condition and that the ammonia on ash and subsequent balance of plant impact(s) are well understood.

Issue: The performance of SNCR on subcritical versus super critical units.

Summary: On February 2, 2012, Dr. Jim Staudt of Andover Tec hnology Partners provided EC/R with draft responses to GRE’s Novembe r 21, 2011 comments on the proposed FIP. In these draft responses, Dr. St audt stated the following:

“GRE claimed in their November 2011 comments that d ata on supercritical units does not provide an indication of SNCR performance at CCS because CCS does not have supercritical units. This is an incorrect statement that does not consider the key process variables of SNCR. Supercritical u nits typically operate at higher furnace temperatures than subcritical units. The h igher furnace temperature

makes NO x reduction with SNCR more difficult due to the comp eting urea

oxidation reaction that causes NO x reduction to drop off at high temperatures. As a result, one would expect SNCR performance to gene rally be better at a subcritical unit than a supercritical unit – all ot her factors being equal.”

Issue: Effectiveness of ammonia mitigation for lignite fly ash.

Summary: Dr. Staudt provided information on the effectivenes s of ammonia mitigation for lignite fly ash in the February 2, 2 012 draft comment responses referenced above. Dr. Staudt referenced three tang entially fired units that use lignite coal and control NO x emissions to under 0.14 lb/MMBtu; Big Brown Unit

1 and Monticello Units 1 and 2. Dr. Staudt stated that “According to The Fly Ash Resource Center, both the Big Brown Plant and the M onticello Plant market their fly ash through Boral Materials. The Monticello fl y ash was an approved materialby the Arizona Department of Transportation (July 2 012 and Georgia Department of Transportation (January 2012). Clearly, this fl y ash does not seem to be adversely impacted.”

Recent information obtained by EC/R indicates that the Texas, Florida, and Louisiana Departments of Transportation (DOT) have approved Big Brown’s fly ash; 1,2,3 however, EC/R could not verify that Arizona or Geo rgia DOT approved Big Brown’s fly ash.

Dr. Staudt concluded that “The assumption that GRE has made, that the Coal Creek plant would be unable to market its fly ash w hile other tangentially-fired boilers that use lignite coal and are controlling t o below 0.14 lb/MMBtu are capable of marketing fly ash, appears to be unjusti fied and overly conservative. While there is a possibility that some portion of t he Coal Creek fly ash may not be marketable without additional treatment, to assume that a treatment method would not be effective at all is also an overly conservat ive assumption. For this reason GRE’s claim that a significant amount of fly ash wo uld be unmarketable appears

unreasonable.”

1 ftp://ftp.dot.state.tx.us/pub/txdot-info/cmd/mpl/fl yash.pdf

2 ftp://ftp.dot.state.fl.us/fdot/smo/website/sources/ cementsource.pdf

3 http://www.dotd.la.gov/highways/construction/lab/qp l/qpl%2050%20fly%20ash.pdf