AgdaPkt 2010-01-25 clsd and regular

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6.2A Page 44 guidelines, trucks and vehicles traveling at 25 to 35 mph on the access road that extends between University Avenue and the proposed tunnel shaft location would generate noise levels of approximately 63 dBA (Leq) at a distance of 50 feet. Ambient noise levels at the east end of the access road (away from University Avenue) are 56 dBA (Leq) during the day based on noise measurements, while measurements indicate that noise levels closer to University Avenue would be approximately 10 dBA higher. Therefore, measured ambient noise levels would increase from 56 to 64 dBA, (Leq) along the east end of this road with Project-related. traffic increases. Since noise increases of 5 dBA are readily noticeable to most people (Caltrans 1998), an 8 dBA to 10 dBA increase in noise level would be a significant noise impact. . Mitigation Measure NOI-l d: Prohibit haul truck operations at Ravenswood Valve Lot during evening and nighttime hours, among other requirements ImpacfNOI-lg may be mitigable through the actions described in Mitigation Measure NOI-ld. However~ space may not be available or it may not be feasible to distribute trucking activities over several routes to reduce noise impacts. As a result, existing ambient noise levels may be increased by more than 5 dBA (Ldn), which would be a significant and potentially unavoidable increase. Impact NOI-lh: Single event noise from daytime haul truck operations along the Newark Valve Lot and Ravenswood Valve Lot access roads would create a substantial temporary increase in ambient noise levels in the project vicinity. Single-event noise associated with haul truck pass-bys associated with both the Newark Valve Lot and the Ravenswood Valve Lot within approximately 160 to 500 feet and having direct line of sight to residential dwellings would exceed the 70 dBA speech interference threshold and would be considered a significant impact. . Mitigation Measure NOI~l e: Prohibit haul truck operations at Newark and Ravenswood Valve Lots during evening and nighttime hours Mitigation Measure NOI-le requires that specific areas within haul roads and routes be selected and located to reduce exposure and increase setback distance to noise sensitive receptors. Still, maximum noise levels from haul trucks would exceed 70 dBA within 160 to 500 feet, depending on noise emissions from a particular truck, and would remain significant and unavoidable. Haul truck operations will be prohibited during nighttime hours, which would partially mitigate the noise impact. However, due to the anticipated setback distances of residents along these haul roads, single-event noise levels generated by haul trucks may not be feasibly reduced to 70 dBA, and if not, this would remain a significant impact. Impact NOI-2a: Nighttime pipeline construction activities would generate noise levels beyond the time limits allowed for construction activities and in excess of noise increase limits establis.~~H~'Y..l~~~1..j.~~~~~~~i~J:lS... . Preliminarily, there are three trenchless crossings and two open-trench crossings where pipeline construction could occur during daytime or nighttime hours. These locations are listed in Draft EIR Table 4.12-15. Such proposed construction hours would occur outside the time limits established by the local jurisdictions' noise regulations. Nevertheless~ local noise ordinances allow noise to occur beyond these time limits if the established noise limits applicable to hours outside the time limits can be met. However, the Project's construction-related noise levels would exceed local noise ordinance limits. In addition, because the entities with control over the roads/railroads (e.g., Caltralls, railroad companies) could require the SFPUC to perform nighttime work despite local jurisdiction.s' noise ordinances, continuous or nighttime 34