Modeling Report for a BART Assessment of the Big Stone I Coal-Fired Power Plant, Big Stone City, South Dakota October 2009 Prepared For: Big Stone I Otter Tail Power Company, Big Stone City, South Dakota Prepared By: TRC Environmental Corporation 650 Suffolk Street Lowell, Massachusetts 01854 (978) 970-5600 TABLE OF CONTENTS Page 1. INTRODUCTION ........................................................................................................................... 1-1 2. SOURCE DESCRIPTION ............................................................................................................. 2-1 3. GEOPHYSICAL AND METEOROLOGICAL DATA ............................................................... 3-1 3.1 Terrain ...................................................................................................................................... 3-1 3.2 Land Use ................................................................................................................................... 3-1 3.3 Meteorological Data Base ........................................................................................................ 3-2 3.4 Air Quality Monitoring Data .................................................................................................. 3-10 4. AIR QUALITY MODELING OPTIONS ..................................................................................... 4-1 4.1 Modeling Domain ..................................................................................................................... 4-1 4.2 Meteorological Modeling Options ............................................................................................ 4-1 4.2 Dispersion Modeling Options ................................................................................................... 4-2 4.3 Visibility Calculations .............................................................................................................. 4-3 5. RESULTS ........................................................................................................................................ 5-1 6. REFERENCES ................................................................................................................................ 6-1 APPENDIX A –CALPOST VISIBILITY METHOD 8 A-1 APPENDIX B – MM5 CONFIGURATION B-1 APPENDIX C – CALMET CONTROL FILE C-1 i LIST OF FIGURES Page Figure 3-1. Terrain elevations for the CALMET and CALPUFF modeling domain at 4 km resolution. The locations of the Big Stone facility and Class I areas are also shown. .............................................................................................................................. 3-3 Figure 3-2. Dominant land use categories at 4 km resolution on the CALMET and CALPUFF modeling domains. The locations of the Big Stone facility and Class I areas are also shown. ....................................................................................................... 3-4 Figure 3-3. Plot of upper air stations available in the modeling domain. ........................................... 3-8 Figure 3-4. Plot of surface and precipitation stations available in the modeling domain. .................. 3-9 Figure B-1. Map showing the MM5 Domain 1 (36-km) and Domain 2 (12-km). ............................. B-4 ii LIST OF TABLES Page Table 2-1: Point Source Parameters and Emission Rates 2-2 Table 2-2: PM10 Size Distribution1 2-2 Table 2-3: PM10 Speciation and Size Distribution 2-3 Table 3-1: U.S. Geological Survey Land Use and Land Cover Classification System 3-5 Table 3-2. Default CALMET Land Use Categories and Associated Geophysical Parameters based on the U.S. Geological Survey Land Use Classification System (14- Category System) 3-6 Table 3-3. Meteorological Data Sources and Parameters Available 3-7 Table 4-1. Rayleigh Scattering Term (Mm-1) for each Class I area as a Function of Elevation 4-6 Table 4-2. Annual Averaged Conditions Levels of Aerosol Components (μg/m3) to Define Natural Background (FLAG 2008) – Method 8 values per Class I Area 4-6 Table 4-3. Monthly Site-Specific RH adjustment factors f(RH) values for hygroscopic species – Small ammonium sulfate and ammonium nitrate particles - Method 8 (FLAG, 2008) 4-7 Table 4-4. Monthly Site-Specific RH adjustment factors f(RH) values for hygroscopic species – Large ammonium sulfate and ammonium nitrate particles – Method 8 (FLAG, 2008) 4-7 Table 4-5. Monthly Site-Specific RH adjustment factors f(RH) values for hygroscopic species – Sea salt particles - Method 8 (FLAG, 2008) 4-7 Table 5-1. Visibility impacts for 2002. Constant (1 ppb) ammonia. 5-2 Table 5-2. Visibility impacts for 2006. Constant (1 ppb) ammonia. 5-2 Table 5-3. Visibility impacts for 2007. Constant (1 ppb) ammonia. 5-2 Table 5-4. Visibility impacts with ALM considered for 2002. 5-3 Table 5-5. Visibility impacts with ALM considered for 2006. 5-3 Table 5-6. Visibility impacts with ALM considered for 2007. 5-3 Table B-1 Domain Configuration and Parameterizations for 2006 and 2007 MM5 Simulations. The Lambert Conical Conformal (LCC) map projection is used in the MM5 modeling. B-3 Table B-2. Sigma Levels used in the North American MM5 Simulations for 2006 and 2007. B-5 Table B-3. Performance Statistics by Year – MM5 Simulations – 12-km Grid Resolution B-8 iii 1. INTRODUCTION TRC Environmental Corporation has conducted a site-specific BART (Best Available Retrofit Technology) modeling assessment of the Big Stone I coal-fired power plant facility located near Milbank and Big Stone City in South Dakota to determine if this facility is subject to BART controls on emissions. This report is a modeling assessment of baseline impacts from the Big Stone I power plant facility to determine whether the Big Stone I cyclone-fired boiler is subject to BART. On July 6, 2005 the U.S. Environmental Protection Agency (U.S. EPA) published in the Federal Register the “Regional Haze Regulations and Guidelines for Best Available Retrofit Technology (BART) Determinations” (40 CFR Part 51). The regional haze rule requires States to submit implementation plans (SIPs) to address regional haze visibility impairment in 156 Federally- protected parks and wilderness areas, commonly referred to as “Class 1 Areas”. The final rule addresses BART-eligible sources, which are defined as sources that have the potential to emit 250 tons or more of a visibility-impairing air pollutant, were put in place between August 7, 1962 and August 7, 1977 and whose operations fall within one or more of 26 specifically listed source categories, of which Coal-Fired Power Plants are one. In January 2009, a modeling protocol was submitted by TRC for the Big Stone I BART modeling based on the use of fine scale meteorological modeling, MM5 data and hourly surface meteorological observations. In response to comments received from Environmental Protection Agency (EPA) and the Federal Land Managers (FLMs), a revised protocol was submitted in June 2009, proposing the use of higher resolution MM5 data with the EPA-recommended modeling input parameters. Based on further discussions with EPA, the FLMs and South Dakota Department of Environment and Natural Resources (DENR), subsequent revisions were made to the June protocol on August 31, 2009. DENR approved the revised protocol in a letter dated September 18, 2009. The modeling described in this report is consistent with the DENR’s approved protocol (except as noted below) and is based on the emissions data described in the June 2009 TRC protocol along with the August 2009 revisions to incorporate EPA-recommended model switch settings and meteorological configuration. The exceptions to the protocol include the use of MNITRATE=0 instead of MNITRATE=1 in POSTUTIL for the baseline runs and the use of MNITRATE=3 for a set of alternative runs. See Section 3.4 for a more detail discussion. Also, the variable IUTMZN referred to in the EPA-recommended list of variables was not assigned because that variable is not used when using a Lambert Conformal projection. The purpose of the modeling is to assess the visibility impacts of sulfur dioxide (SO2), particulate matter (PM) and nitrogen oxides (NOx) emissions from the Big Stone I boiler and compare the impacts to the 0.5 change in deciview threshold at all the federally mandatory Class I areas. Since there is no Class I area within the 300 km radius usually applied, the South Dakota Department of Environment and Natural Resources requested that the Class I areas between 300 km and up to 625 km away from the Big Stone I facility sources be modeled. A total of eight Class I areas are located between these distances: two wilderness areas: Boundary Waters Canoe Area Wilderness Introduction 1-1 and Rainbow Lake Wilderness, one National Wildlife Refuge (NWR): Lostwood and five National Parks: Voyageurs NP, Theodore Roosevelt NP, Badlands NP, Wind Cave NP and Isle Royale NP. However, Rainbow Lake Wilderness is one of two Class I areas where the visibility analysis is not required (http://www.dnr.state.wi.us/org/aw/air/modeling/ psd.htm), so it is not included in the modeling analysis. The MM5 datasets distributed by WRAP did not extend far enough in the East to include the Isle Royale NP or cover all of the Boundary Waters Class I area. The re-extracted MM5 data for 2002 and new MM5 domains for 2006 and 2007 include these areas. The CALMET and CALPUFF non-steady-state models (Scire et al., 2000a,b) are recommended by the U.S. EPA (Federal Register, 6 July 2005) to perform source-specific subject-to-BART screening. The CALPUFF