Reso13 PC 13-09 2859 Initial Study Mitigated Negative Declaration Kensington

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Parking Lot Noise The proposed surface parking lot, with a total of 27 spaces, will be located on the southwestern portion of the site immediately adjacent to residences. The major noise sources attributed to parking lot activities are the sounds of vehicles as they drive by, noise generated when vehicles start their engines, door slams and the occasional sound of car alarms or horns. Maximum and average noise levels resulting from activities in the proposed parking lot were calculated in SoundPLAN at the nearest residential location. Predicted parking lot noise levels were then compared to existing ambient noise levels assuming the additional acoustical shielding provided by the proposed building. Maximum instantaneous noise levels at 30 feet from parking lot activities would range from about 54 to 64 dBA LmaX as a result of typical activities and could reach 74 dBA Lm�when car alarms are sounded. Maximum instantaneous noise levels at 15 feet from parking lot activities would range from about 60 to 70 dBA Lm� as a result of typical activities and could reach 80 dBA Lm�when car alarms are sounded. Such levels could exceed ambient conditions by 5 dBA Lm� during the day and could exceed ambient conditions by 5 to 15 dBA Lm� at night. When car alarms are sounded, maximum noise levels could exceed ambient conditions by 10 to 15 dBA Lm� during the day and by 20 to 25 dBA Lm� at night. Maximum instantaneous noise levels resulting from the parking lot,particularly during evening and nighttime hours, would likely be considered intrusive and could cause sleep disturbance even with the residential windows shut. The hourly average noise level resulting from noise-generating activities in the proposed parking lot would reach 42 dBA Leq at a distance of 40 feet from the acoustical center of the parking area and would fall below typical ambient hourly average noise levels both day and night. Similarly, CNEL noise levels resulting from the operation of the parking lot would reach 49 dBA CNEL at the nearest residential receivers, but would be below existing ambient conditions. On an hourly average or daily average basis, the operation of the proposed parking lot would not substantially increase ambient noise levels above levels existing without the project. Recommendations As identified above, maximum instantaneous noise levels resulting from the parking lot, particularly during evening and nighttime hours, would likely be considered intrusive and could cause sleep disturbance. The project plans the construction of a 10-foot noise barrier along the south property boundary to reduce noise levels at outdoor use areas and the ground floor of the residential units. Windows at the second and third stories of the residential units would not be shielded by the proposed noise barrier. The following additional recommendations should be considered to reduce the noise exposure at the residential fa�ades: • Cover parking areas with a solid roof structure (see Figure 3). The roof structure could provide an additional5 to 10 dBA of noise reduction from maximum instantaneous noise levels generated by engine starts, door slams, alarms, horns, and voices. The roof structure could be tied into the proposed noise barrier along the south boundary of the site to provide continuous shielding. 5