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2 Environments 7.B. - Page 95 <br /> With the incorporation of these measures,the impacts of the proposed project from noise during <br /> construction and operation would be less than significant. (Less than Significant Impact with <br /> Mitigation Incorporation) <br /> b) Exposure of persons to or generation of excessive groundborne vibration or groundborne <br /> noise levels? <br /> Based on vibration levels for construction equipment in the Federal Transit Administration (FTA) <br /> Noise and Vibration Impact Assessment manual (May 2006),typical project equipment such as <br /> dozers and loaded trucks could generate vibration below the level of concern for most structures. <br /> The highest source of vibration would be the pile driving for the replacement pump station, 100 feet <br /> from the US 101 bridge structure. At this distance,the vibration from pile driving would be below <br /> the level that would damage the US 101 bridge. Vibration would not affect the other nearby <br /> structures on the east side of US 101,which consists of an automobile dealership, approximately <br /> 300 feet from the pump station and wet well,and the One Marina development,approximately <br /> 400 feet from the location of the pile driving equipment. (Less than Significant Impact) <br /> c)A substantial permanent increase in ambient noise levels in the project vicinity above <br /> levels existing without the project? <br /> The US 101 undercrossing and Bair Island storm drain pump station would not result in a <br /> substantial permanent increase in ambient noise levels in the vicinity of the project. Noise levels <br /> from pedestrian and bicycle use of the undercrossing would be less than the existing levels without <br /> the project. The submerged replacement pumps at the new pump station would not operate unless <br /> there was an electrical outage and would not increase noise level above background levels. The <br /> emergency generator would have a noise enclosure,which would reduce noise levels to below the <br /> typical background levels from traffic on the adjacent highway. (Less than Significant Impact) <br /> d)A substantial temporary or periodic increase in ambient noise levels in the project vicinity <br /> above levels existing without the project? <br /> The temporary increase in ambient noise levels from the construction of the proposed project would <br /> not be substantial. While occasionally audible,the increases would be within the range of ambient <br /> noise levels from traffic on US 101. (Less than Significant Impact) <br /> e)For a project located within an airport land use plan or, where such a plan has not been <br /> adopted, within two miles of a public airport or public use airport, would the project expose <br /> people residing or working in the project area to excessive noise levels? <br /> The project area is more than 1.5 miles from the San Carlos Airport and beyond the 55 dBA CNEL <br /> noise contour established in the San Carlos Airport Land Use Plan. The project would not expose <br /> people living or working in the area to excessive airport noise. (No Impact) <br /> 2-55 US 101 Pedestrian Undercrossing and Bair <br /> Island Road Storm Drain Pump Station Project <br />