75C - PH - BRISTOL EIR FROM WARNER TO ST. ANDREW

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pollutants are a large -scale phenomenon and should be analyzed on a regional basis rather than a local one. The "worst case" assumptions made in the Cadne 3 modeling process included: wind speed of 1 meter per second, wind direction parallel to the road, peak hour traffic volumes, and atmospheric stability class of F (most stable) for 1- hour averages and class D for 8 -hour averages. The results appear in Table 15 and represent "worst case" conditions. Actual levels would probably be less. Three scenarios were analyzed based upon traffic volumes for 1987 and for future year 2006 conditions both with and without the project. As shown in Table 15, the future design year carbon monoxide concentrations adjacent to the intersections most affected by the project will not equal or exceed the 35 ppm one -hour federal standard with or without the roadway widening proposed. Additionally, the 20 ppm one -hour state standard should not be exceeded after completion of the proposed project. Conversely, state one -hour standard exceedances may occur in the future design year under the "No- Build" condition at the intersections analyzed. Ambient CO levels in the design year (9.5 ppm) are projected to exceed the eight -hour state and federal standards (9.0 ppm) in the project vicinity. Carbon Monoxide (CO) contributions at the intersections analyzed are also projected to exceed the eight -hour standards, regardless of the alternative. The number of days exceeding applicable CO standards within the project area, however, are expected to be reduced, under the 'build" alternatives. Current CO concentrations without the project exceed the state one -hour and eight -hour standards and the federal eight -hour standards. To facilitate comparison between scenarios, Table 15 shows the projected CO concentrations directly attributable to the roadway without adding background (or ambient) CO levels. The ambient CO concentrations shown in Table 15 should be added to the levels generated by the traffic at the intersections analyzed to reflect the expected concentrations at various distances from the intersections. The carbon monoxide levels at sensitive receptor locations nearest the intersections analyzed are shown in Table 15. With the 'build" alternative, one -hour CO levels will decrease by 0.8 to 2.8 ppm. Under eight -hour conditions, CO levels will decrease by 0.3 to 1.0 ppm. Figure 18 illustrates the four intersections analyzed, the closest residential lots, and the closest sensitive receptor location. As shown therein, the closest residential land uses to the intersection of Bristol Street and Memory Lane are three single - family dwellings (SFD) and a multi - family apartment complex. The first SFD lies 200 feet east of the Bristol Street centerline and the IV -13 75C -148