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Grand Avenue Widening Project Environmental Impact Report Section 3.0 Local Air Quality Local air quality is a major concern along roads. CO is a primary pollutant which is directly emitted from a variety of sources, the primary source being motor vehicles. For this reason, CO concentrations are usually indicative of the local air quality generated -by a road network and are used to assess its impacts on local air quality. Comparisons of CO levels with the federal and state AAQS indicate the severity of the existing concentrations for receptors in the project area. The federal and state AAQS for CO were provided earlier in Table 3.4-1. CO levels due to roads in the vicinity of Grand Avenue were assessed with the CALINE4 computer model, a fourth generation line source air quality model developed by the California Department of Transportation ("CALINE4," Report No. FHWA/CA/TL-84/15, June 1989). The purpose of the model is to assess air quality impacts near transportation facilities in the microscale region. The microscale region encompasses an area a few thousand feet around a pollutant source. Given source strength, meteorology, site geometry and site characteristics, the model can reliably predict pollutant concentrations. The methodology for forecasting existing and future CO levels in the Grand Avenue area is described in greater detail later in Section 3.3.4 (Methodology Related to Air Quality). The CALINE4 computer modeling for CO was conducted for three intersections in the vicinity of the proposed project: Grand Avenue/First Street, Grand Avenue/Frait Street and Grand Avenue/Seventeenth Street. Receptors were located approximately 25 feet from the nearest existing land uses. These receptor locations are shown in Figure 3.4-1. The existing CO concentrations at these intersections are shown on Table 3.4-2. The existing background CO concentrations for 1997 were taken from the AQMD CEQA Air Quality Handbook (1993), the latest available source for this information. The existing 2000 CO background concentrations are available for the air quality monitoring station in Anaheim, which is the nearest representative station. The existing background CO levels are estimated to be 7.3 parts per million (ppm) for one hour and 5.8 ppm for eight hours. Therefore, 7.3 ppm was added to the worst case on hour CO projections and 5.8 ppm was added to the eight hour projects, to account for background CO levels on Grand Avenue, as shown in Table 3.4-2. The traffic data for the Grand Avenue widening project were provided by P&D Consultants, Inc. (July 2001). The peak hour levels of service (LOS) on Grand Avenue are important in the CALINE4 computer modeling because they determine congestion levels. The more congested an intersection, the lower the travel speeds. The speeds used in the modeling determine the vehicular emissions factors. The lower the speeds, the higher the emissions factors and, therefore, the higher the CO levels. PM peak hour traffic is used in the CALINE4 computer model as the worst case traffic scenario because PM peak hour traffic volumes are higher than AM peak hour volumes. The modeling results of the existing CO levels at the three project area intersections are shown in Table 3.4-2. As shown, the existing one hour CO levels range from 10.9 to 11.3 ppm, well below the AAQS of 20 ppm. The eight hour CO levels range from 7.6 to 7.9 ppm, also well below the AAQS of 9 ppm. F:IPROJ-EWGrand eirlNew Text- GrandlSection 3 SplitWection 3.4.doc Page 3.4-5