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<br />John Stark, Community Development Director <br />City ofRoseville <br /> <br />November 17, 2006 <br />Page 19 <br /> <br />Carbon monoxide concentrations were projected using the Environmental Protection Agency <br />(EPA) Mobile 6 emission model and the CAL3QHC dispersion model. The Minnesota Pollntion <br />Control Agency's (MPCA) I-hour and 8-hour standards for CO concentrations are 30 parts per <br />million (ppm) and 9 ppm, respectively. <br /> <br />Modeling assumptions used in this analysis were as follows: <br /> <br />Analysis Year: <br />Traffic Mix: <br />Cruise Speed: <br />Cold Stali Percentage: <br />Hot Start Percentage: <br />Wind Speed: <br />T em perature: <br />Surface Roughness: <br />Stability Class: <br />Inspection Maintenance: <br />Oxygenated Fuel: <br />Fuel Program <br />Fuel Reid Vapor Pressure <br />Eight Hour Persistence Factor: <br />Wind Direction: <br /> <br />2030 <br />National default values <br />Posted speed limits <br />20.6 percent for all traffic <br />27.3 percent for all traffic <br />I meter/second <br />-8.8 degrees Celsius <br />108 centimeters <br />D <br />No <br />Ethanol with 2.7 percent oxygen content <br />Convention Gasoline East <br />9.0 Ibs/square inch <br />0.7 <br />36 directions at 10 degree intervals <br /> <br />Background CO Levels <br /> <br />Default background CO concentrations were obtained from the Minnesota Pollution Control <br />Agency. For purposes of the analysis, these background concentrations were adjusted for <br />region-wide increases in traffic volumes. To represent worst-case conditions, there were no <br />reductions of background concentrations to account for vehicle emissions and temperature. The <br />results are summarized in Table 5. <br /> <br />Table 5 <br />Calculation of CO Background Concentrations <br /> <br /> Year 2030 <br />Factor I-Hour Average 8-Hour Average <br />Default 2006 Background 3.0 2.0 <br />Concentration (ppm) <br />Background Traffic Volume 1.8 1.8 <br />Adjustment Factor <br />Werst-Case Background 5.4 3.6 <br />Concentration (pplll) <br />