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<br />VEHICLE-RELATED AIR QUALITY ANALYSIS <br /> <br />Air quality effects were analyzed for the worst-case intersections to determine whether any air <br />quality violations are likely to occur. Although two intersections would have a peak hour level <br />of service of E, traffic queues would not cause any air quality violations under the worst-case <br />scenario. <br /> <br />Methodology and Assumptions <br /> <br />Motor vehicle air quality issues are most frequently associated with carbon monoxide (CO) <br />emissions and the concentrations of those emissions. The MPCA's I-hour and 8-hour standards <br />for CO concentrations are 30 parts per million (ppm) and 9 ppm, respectively. Concentrations of <br />CO are generally highest at intersections with poor levels of service and, consequently, more <br />idling vehicles. An air quality analysis was performed to predict carbon monoxide <br />concentrations at intersections near the proposed Twin Lakes redevelopment site that operate at <br />low levels of service. The air quality analysis incorporates projected afternoon peak hour traffic <br />volumes (including site-generated traffic) representing build conditions year 2020. Carbon <br />monoxide concentrations were projected using the Environmental Protection Agency (EP A) <br />Mobile SA emission model and the CAL3QHC dispersion model at the following intersection: <br /> <br />Intersection <br /> <br />Year 2020 Level of Service <br /> <br />I. Snelling A venue at County Road C <br />2. Fairview A venue at County Road C <br /> <br />E <br /> <br />E (assumes no dual left-turn lanes on County <br />Road C) <br /> <br />The modeling assumptions used in this analysis were as follows: <br /> <br />Cold Start Percentage: <br />Cruise Speed: <br />Analysis Year: <br />Traffic Mix: <br />Wind Speed: <br />Temperature: <br />Surface Roughness: <br />Stability Class: <br />Inspection Maintenance: <br />Oxygenated Fuel: <br />Eight Hour Persistence Factor: <br />Wind Direction: <br /> <br />20.6 percent for intersection traffic <br />30 mph <br />2020 <br />National default values <br />1 meter/second <br />20 degrees F <br />108 centimeters <br />D <br />No <br />Yes <br />0.7 <br />36 directions at 10 degree intervals <br /> <br />Twin Lakes AUAR <br />Traffic, Air and Noise Analysis <br /> <br />-25- <br /> <br />SRF Consulting Group, Inc. <br />May 3. 200I <br />