The noisiest phases of construction would generate approximately 89 Leq at 50 feet (EPA, 1971). The receptors nearest proposed construction activity would be the residents in the Youngstown Mobile Home Park located adjacent to the Service Centerís southern and western boundaries. Residents in homes easterly of the site also would be noise receptors. Consequently, construction noise during construction would generate noise levels up to approximately 90 dBA, Leq at the nearest residences during regrading and resurfacing activities.
Given ambient noise levels at these residences, construction noise would be noticeable; however, many residences generally are less occupied during the daytime. Construction noise would be annoying to those residents who would be home during the day, but it would be a temporary disturbance. During nighttime, temporary construction-related noise could be more noticeable (since background noise is lower) and could annoy the closest residents given the more sensitive nature of the nighttime period. The City of Petaluma Noise Ordinance specifically prohibits construction activity between the hours of 10:00 p.m. and 7:00 a.m. Monday through Friday, and between 10:00 p.m. and 9:00 a.m. on Saturdays, Sundays, and State, Federal, or local holidays. Consequently, construction activities would not be allowed to occur during nighttime hours and would not result in increases in noise levels during these periods.
Transformers on the substation site would generate operational noise. The potential for noise impacts from the transformers is addressed in a Noise Impact Assessment study prepared for the proposed project (EDAW, Inc., 1997). This study found that the two transformers proposed for the site would each generate a noise level of 67 dBA, and a composite noise level of 70 dBA at a distance of four feet. The report predicts a resultant noise level of up to 54.0 dBA at the property line. This projected noise level at the property line with the transformers present would be 0.6 dBA above the ambient noise level, and is not substantial enough to affect the existing ambient noise level, which was calculated to be 58 dBA Leq over a 24-hour period. Consequently, operation of the transformers would be:
Implementation of the project would not result in relocation of existing equipment, maintenance, or service vehicle parking to the boundaries of the project site. Employee parking would be relocated to the northeastern corner of the project site. Noise generated by employee vehicle parking would occur intermittently during daytime hours and would not noticeably increase ambient noise levels.
The following mitigation measures would reduce the potential impact to a less than significant level:
Mitigation Measure X.a-1: To reduce the construction noise effects, PG&E shall ensure that noisy construction activities at the substation site and near residences along the power line route shall be limited to the least noise-sensitive times of day and week as required by the City of Petaluma Noise Ordinance.
Mitigation Measure X.a-2: To reduce the construction noise effects, PG&E shall ensure that all construction equipment used on the substation site and for power line construction shall be adequately muffled and maintained.
Mitigation Measure X.a-3: To reduce the construction noise effects, PG&E shall ensure that all stationary construction equipment (i.e., compressors and generators) shall be located as far as practicable from the eastern and southerly property line.
PG&E shall certify compliance with these measures in scheduled progress reports to the CPUC.
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