### McElmo Creek Main Flare PSD Permit Application McElmo Creek Main Flare PSD Permit Application : : Visibility Impact Visibility Impact Visibility Impact /

Soils and Vegitation Analyses Andrew Chew Andrew Chew to: Dmallory 01/30/2013 03:00 PM Dwight, Per our phone conversation, as our office is wrapping things up in preparation for public notice , here are 2 more topics we hope Tom can help make our write-up more robust: Visibility Impact Analysis  The visibility impact analysis for fulfilling the additional impacts analysis requirement pertains to visibility impairment (e.g., plume blight) in Class II areas. My understanding from Don Shepard is that Hovenweep is the only Class II federal area within 50 km of the Main Flare. The analysis should include Class II areas described below. The Class II visibility impacts analysis is independent of the Class I visibility Air Quality Related Values . Please confirm whether there are other Class II federal and state areas (e.g., potentially sensitive parks, forests, monuments, and recreational areas) within 50 km of the project. (If there is not a specifically designated "Class II area(s)", the project should consider a location(s) where there may be some potential for visibility impairment . For instance, if there is an area where there are terrain features that provide a contrast that makes changes in visibility perceptible , that area may be considered.) Please discuss the potential visual impacts of the project on these areas . Information presented in the EPA 1992 workbook should be considered - 

### U.S. EPA (U.S. Environmental Protection Agency), 19 92. “Workbook for Plume Visual Impact  

### Screening and Analysis.” EPA-450/R-92-023. October. http http:// :// tinyurl tinyurl tinyurl . com / EPA 1992 plume Then based upon the evaluation, conduct a VISCREEN Level 1 analysis (beyond what already was provided for Class I areas) for any identified areas. If necessary, conduct a Level 2 analysis if the Level 1 impacts are exceeded. If there is a valid reason not to conduct an analysis, please provide that narrative.
Soils and Vegetation Analysis  Please characterize the potential impacts to soils and vegetation in consideration of the following suggested additional references to help make the write-up more robust: 

### U.S. EPA (U.S. Environmental Protection Agency), 19 80. “A Screening Procedure for the  

### Impacts of Air Pollution Sources on Plants, Soils, and Animals. Final Report” EPA-450/2-81-078. December. http://tinyurl.com/EPA1980Soils Web Soil Survey (WSS) for the National Cooperative Soil Survey via the USDA Natural Resources Conservation Service. http http:// :// websoilsurvey websoilsurvey websoilsurvey .

nrcs . usda . gov / app / HomePage HomePage HomePage.

htm From site: 

### Web Soil Survey (WSS) provides soil data and inform ation produced by the National Cooperative Soil Survey. It is operated by the USDA Natural Resources Conservation Service ( NRCS ) and provides access to the largest natural resour ce information system in the world. NRCS has soil maps and data available online for mo re than 95 percent of the nation’s counties and anticipates ha ving 100 percent in the near future. The site is updated and maintained online as the si ngle authoritative source of soil

### survey information.

Links to recent EPA Region 9 Fact Sheets that include discussions about soils and vegetation , as examples of what we have proposed in our permits, are as follows: Pio Pico, Item IV.2 -  http://www.regulations.gov/#!documentDetail;D=EPA-R09-OAR-2011-0978-0005 Palmdale - http://www.regulations.gov/#!documentDetail;D=EPA-R09-OAR-2011-0560-0004  SPI Anderson - http://www.regulations.gov/#!documentDetail;D=EPA-R09-OAR-2012-0634-0003  Please let me know if you have further questions. Thank you.
- Andrew

------------------------------------------- Andrew Chew, P.E. T: (415) 947-4197 | F: (415) 947-3579 | chew.andrew@epa.gov U.S. EPA, Region 9, Air Permits Office (AIR-3) | 75 Hawthorne St., San Francisco, CA 94105