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MCVEHIL-MONNETT <br />a��ASSOCIATES, INC. <br />Air Quo4ty • Environmental Monagemenl <br />December 15, 2015 <br />Mr. Luke J. Danielson <br />Law Offices of Luke J. Danielson, P.C. <br />219 N. Iowa Street <br />Gunnison, CO 81230 <br />RE: La Plata County Road 120 Air Quality Modeling Analysis, MMA Project No. 2727-15 <br />Dear Mr. Danielson: <br />McVehil-Monnett Associates, Inc. (MMA) is pleased to provide this analysis in response to your <br />request to quantify potential traffic -related air quality impacts to residents along the northern <br />portion of La Plata County Road 120, from the GCC facility entrance to State Highway 140. <br />Specifically, MMA was asked to perform air dispersion modeling using accepted regulatory <br />methods (and following EPA guidance) in concert with the two levels of traffic data provided in <br />Table 6 of Roadrunner Engineering, LLC's Traffic Impact Assessment' (Roadrunner TIA). <br />Figure 1 attached presents the study area, showing the unpaved and paved sections of north <br />County Road 120 as well as nearby resident/structure locations. <br />MMA's analysis focused on the short-term (24-hour) impacts of particulate matter less than or <br />equal to 10 micrometers in diameter (PMIo) from resuspended dust generated by traffic on the <br />road. PM10 is classified as a "criteria" pollutant for which EPA has established a primary (and <br />identical secondary) 24-hour National Ambient Air Quality Standard (NAAQS) of 150 <br />micrograms per cubic meter (gg/m3). A primary standard is designed to provide public health <br />protection, including protecting the health of sensitive populations such as asthmatics, children <br />and the elderly. A secondary standard provides public welfare protection, including protection <br />against decreased visibility and damage to animals, crops, vegetation, and buildings. EPA is <br />concerned about PM10 because these particles generally pass through the throat and nose and <br />enter the lungs. Once inhaled, these particles can affect the heart and lungs and cause serious <br />health effects .2 <br />Summary of Results <br />A brief summary of the analysis results is presented below. Details of the study are presented in <br />later sections of this report. <br />' Roadrunner Engineering, LLC. "GCC Energy LLC, King II Coal Mine, County Road 120 Traffic Impact <br />Assessment", revised July 31, 2015. <br />2 http://www3.epa.gov/airquality/particlepollution/ <br />9250 East Costilla Avenue 1 Suite 630 1 Greenwood Village, Colorado 80112 <br />303/790-1332 1 Fax 303/790-7820 <br />www.mevehil-monnett.com <br />