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

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for approximately 167 residential front yard activity areas. Of these dwellings, 68 front onto Bristol Street with direct vehicular access and 99 have vehicular access to a rear alley or to a side street. In addition, seven of these dwellings have noise impacts in rear yard activivy areas (six yards surrounded by chair, link and one with no fencing). Some of these homes would be removed to widen the street. Future noise levels for 15 typical sensitive receptors along the Bristol Street frontage were then estimated to determine what sort of mitigation would be necessary to reduce noise to acceptable levels. In several cases, construction of a six or eight -foot high wall, at the right -of -way line, would achieve satisfactory noise attenuation. In most cases, however, construction of a sufficient noise barrier would conflict with existing driveways and pedestrian access or would reduce vehicular sight distances at comers. If such situations were avoided, the resulting non - contiguous noise barrier would not meet the Caltrans criteria for minimum effectiveness. Second line receptors are buildings that are currently acoustically shielded by a row of buildings located between them and the roadway. Since the proposed project could ultimately result in the removal of 200 existing buildings adjacent to Bristol Street, there is the potential for adverse noise impacts at approximately 200 second line receptors. Barriers should be constructed to shield the second -line receptors that will exceed the 67 Leq criteria (see Figure 19). In addition, barriers could be constructed per current Caltrans practices to shield those second -line receptors where exterior noise levels will approach the 67 Leq criteria. It should be noted that final design may not include barriers at the locations identified as approaching the 67 Leq criteria. Noise attenuation measures that will be incorporated into the "with project" alternative, if feasible, include: 1. Replacement of existing barriers that are removed to widen the street by barriers at least six feet high. 2. Construction of six-foot block walls on corner lots with access to cross streets, where adequate vehicular sight distances can be maintained. 3. Construction of solid sound barriers adjacent to school playgrounds and athletic fields to meet federal exterior noise criteria. 4. Construction of six-foot walls to shield residential rear yards, where such rear yards face Bristol Street. 5. Construction of six-foot walls at second -line receptor property lines, to meet the 67 Leq federal criteria. IV -21 75C -156