CCP 09-30-2002 - Laserfiche WebLink

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A~ _ The guidance provided in "EA W Guidelines should also be followed for an A UAR. .. Mitigation proposed to eliminate any potential problems may be presented under Item 21 and merely referenced here. The MPCA staff should be consulted regarding possible ISP requirements for certain proposed developments; although the RGU may not want to assume responsibility for applying for an ISP for specific developments, it may be desirable to coordinate the A UAR and ISP analyses closely. Motorized vehicles affect air quality by emitting airborne pollutants. Changes in traffic volumes, travel patterns, and roadway locations affect air quality by changing the number of vehicles in an area and altering traffic flow patterns. The effect of the development on air quality was assessed by considering the changes in carbon monoxide, the primary airborne pollutant that emitted from motorized vehicles. Carbon Monoxide Carbon monoxide (CO) is the traffic-related pollutant of most concern in the Twin Cities Metropolitan Area. Concentrations of CO are generally highest at intersections with poor levels of service and, consequently, more idling vehicles. The MPCA has established state standards (or maximum permissible concentrations) for CO of 30 parts per million (ppm) for a I-hour period (average concentration), and 9 ppm for an 8-hour period. The MPCA I-hour standard is more stringent than the federal standard of 35 ppm. The Environmental Protection Agency (EP A) reclassified Minneapolis/St. Paul as an attainment area for CO in 1999. The attainment status is contingent upon the implementation of measures to assure that CO concentrations remain below standards. In compliance with this contingency, air quality analyses of "worst-case" conditions were performed for the study area to estimate the effect of the proposed campus expansion on future CO concentrations at key intersections the study area. These analyses include monitoring of existing background CO concentrations and modeling future CO concentrations at worst-case intersections, . Carbon Monoxide Modeling Methodology and Assumptions Carbon monoxide concentrations near the intersections were predicted using forecasted traffic volumes, current and proposed intersection geometries, optimized signal timing, and with computer models, including the U,S. EPA MOBILE5A1 emission model and the U.S. EP A CAL3QHC dispersion model. The scope of the air quality analyses was developed based on input from MPCA staff. The modeling assumptions used in this analysis are shown in Table 17. I The EP A has recently released the improved MOB1LE6 emissious model. At the time of this analysis, the MPCA . had not yet approved regional assumptions for MOBILE6 inputs, The MOBILE5A model is still approved for use by the EPA, Guidant Campus Master Plan Draft AUAR -41 - September 2002