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<br />6.2A <br />Page 45 <br /> <br />construction at these five crossing locations may be required and if so, could. result in significant <br />and unavoidable noise impacts. <br /> <br />. Mitigation Measure NOI-2: Noise reduction techniques and controls <br /> <br />Mitigation Measure NOI-2 would reduce noise impacts by requiring the contractor to use noise <br />control techniques such as relocating affected residential receptors and prohibiting pile driving at <br />night to reduce construction noise impacts. While relocation of Menlo Park residents within 160 <br />feet of nighttime pipeline and pit construction, and San Mateo Residents within 65 feet of <br />nighttime pipeline and pit construction would avoid nighttime noise limits on noise sensitive <br />receptors, it is unknown whether all affected residents would agree to relocation. If any residents <br />remained, construction of the project would expose people to noise levels beyond the time limits <br />allowed for construction activities and in excess of nighttime standards established by local <br />jurisdictions' noise ordinances. Given the uncertainty of whether this measure can be fully <br />implemented and all affected residents can be relocated, this impact could be unavoidable. <br /> <br />Impact NOI-2b: Nighttime tunnel construction at the Ravenswood Shaft would expose <br />people to, and generate, noise levels beyond the time limits allowed for construction <br />activities and in excess of nighttime standards established by local jurisdictions' noise <br />ordinances. <br /> <br />Tunnel construction at the Ravenswood Shaft would occur over a four and a half to five year <br />period, 24-hours per day on weekdays, with nighttime activities at the surface limited to the <br />support of underground tunnel construction, and with maintenance activities above and <br />underground on Saturdays and possibly Sundays, and excavation and lining may continue on <br />weekends, as necessary ~ which would not be consistent with the time limits for construction <br />activities specified by noise ordinances of the cities of East Palo Alto (7 a.m. to 8 p.m. on <br />weekdays and weekends), and Menlo Park (8 a.m. to 6 p.m. on weekdays only). In addition, <br />excavation and lining might also occur on weekends and would also not be consistent with these <br />time limits. Therefore, the Project's proposed continuous weekday construction hours would <br />generate and expose people to noise levels beyond the time limits established by these cities' <br />noise regulations to control construction noise. However, these ordinances allow construction <br />noise to occur beyond these time limits if it complies with the established noise limits applicable <br />to hours outside the time limits. To assess the Project's consistency with local noise ordinance <br />limits, estimated nighttime tunnel-related construction noise levels at the property line of the <br />closest residential receptors were compared to these limits. In summary, noise levels generated <br />by operation of cranes, ventilation fan, front-end loader, segment truck, and stationary equipment <br />could exceed ordinance nighttime noise limits, resulting in a significant impact. <br /> <br />. Mitigation Measure NOI-2: Noise reduction techniques and controls <br /> <br />Impact NO I ~ ~b ~()ul~. ~e p~r.tia1.lY ll1itig~ted.t~r()\lg~ tl:1~ .~~ti,?I.1s. 4~~(;.tjl>~~.iI1. Mit.ig~ti9~..M~~.s.tl.r.e.. . <br />.. ......:NOI~2;..However; the noise-reduction'levelspresented 'aretypically'achievable'onlyfor stationary' <br />noise sources with noise barriers erected close to the noise generating device. In addition, <br />barriers may not be effective at mitigating all noise-generating sources, such as the crane, which <br />is used to lower workers in and out of the shaft at night, and as work at night will sometimes be <br />required, noise levels Dlay at times exceed the local noise ordinances. Therefore, this noise <br />inlpact may be unavoidable. <br /> <br />Impact NOI-2d. Any weekend pipeline or tunnel construction activities that occur within <br />the cities of Newark, Menlo Park, and Redwood City would expose people to, and generate, <br />noise levels beyond the time limits allowed for construction activities and in excess of <br />standards established by these local jurisdictions' noise ordinances. . <br /> <br />35 <br />