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<br />6.2A <br />Page 40 <br /> <br />dewatering during Project operation. Use of the Ravenswood Valve Lot for construction staging <br />over a four and a half to five year period would affect the existing land use character of the <br />vicinity throughout the construction period, which would result in a significant land use impact. <br /> <br />. Mitigation Measures AIR-la, AIR-Ib would reduce emissions of fugitive dust and diesel <br />exhaust. <br />. Mitigation Measures NOl-Ia, NOl-lb, NO/-Ie, NOI-Id, NOI-2, NOI-3a, NOI-3b, NO/- <br />3e, NOr-3d, NOI-3e, NOI-3f and NOI-4h would limit construction hours near schools and <br />childcare facilities, construct noise barriers, temporarily relocate residents, among other <br />things. <br />. Mitigation Measures TRN-l a, TRN-l b, TRN-4, and TRN-6 would reduce construction <br />traffic impacts on local roads and residential areas and require coordination with <br />emergency providers. <br /> <br />These measures would help to reduce the Project's air-quality, noise and traffic impacts on the <br />existing land use character; however, these impacts would remain significant and unavoidable <br />because the land use character would still be affected by pollution, noise and truck traffic for up <br />to five years. <br /> <br />Impact NOI...la: Pipeline construction would result in a substantial temporary increase in <br />existing ambient noise levels in the Project vicinity. <br /> <br />The noisiest phase of construction would be the construction of the jacking pits. Trenchless <br />construction methods (Le., jack-and-bore or microtunneling) would be used to cross certain <br />major roadways, railroads, and streams. Additional noise impacts would occur at locations where <br />pile driving (using vibratory or impact methods) would be used for construction of jacking pits <br />(used for trenchless crossings), and if these crossings were located close to sensitive receptors. <br /> <br />While trenchless construction at some crossings would be completed in one month, this <br />construction could occur for up to three months where streets are wider. Pit construction would <br />require pile driving at some locations, but pile-driving activities would be complete in <br />approximately two weeks. While the construction contractor would use vibratory pile drivers <br />wherever practicable, impact pile drivers could be required at some locations because of soil <br />conditions. After pit construction, construction noise would decline because equipment would <br />operate below grade within the pit, and the sides of the pit would help to reduce construction <br />noise at adjacent receptors. Such efforts would limit the adverse effects of construction noise at <br />these locations. As indicated in Table 4.12-13, construction noise in the pit vicinity would <br />exceed the 70 dBA speech interference criterion by up to 39 dBA at the closest sensitive <br />receptors. Sensitive receptors within approximately 100 feet of jacking pits (and up to 900 feet <br />from pile drivers) could be subject to temporary noise increases and to significant speech <br />interference impacts. Therefore, Project construction could result in significant temporary <br />increases in ambient noise levels. <br /> <br />. .Mitig(ltionMeasureNOI~ra:N oiseC()l1trolMeasures <br /> <br />These measures would reduce noise impacts on sensitive receptors by requiring the contractor to <br />use noise control measures to reduce construction noise levels to the extent feasible. Some <br />locations within close proximity to particularly loud noise sources, exposed to elevated noise <br />sources for which noise barriers would not provide shielding, or second story facades for which <br />barriers may provide less noise reduction may be exposed to temporary Project noise levels <br />exceeding the speech interference noise threshold. Therefore, daytime construction noise would <br />be significant and unavoidable. <br /> <br /> <br />30 <br />