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305 <br /> <br />Excavation activities present the second greatest intensity <br />potential for noise impacts on the adjacent residents. The <br />equipment directly involved in the excavation of the site, as well <br />as the trucks used to haul the dirt from the site, could produce <br />high noise levels. With the exception of pile driver equipment, <br />the peak noise level for most of the equipment that will be used <br />during the construction of the Main Street Concourse is 96 dBA at <br />a distance of 50 feet. <br /> <br />There may be noise impacts on Phase I single-family attached <br />residences from construction of the later portions of Phase I and <br />Phase II residential tower, hotel and parking structure. <br />Construction noise generally produces short-term impacts. During <br />the construction of Phase II, heavy equipment noise may impact the <br />residents occupying the buildings constructed during Phase I. This <br />equipment would probably include scrapers, graders, front loaders <br />and heavy trucks. Moreover, if pile driving is used for the <br />foundations of the high-rise, the noise impact would be <br />significant. <br /> <br />The distance between Phase I buildings and Phase II construction <br />sites could be as close as 50 feet. At this distance, the noise <br />generated by construction equipment can be substantial. <br /> <br />Because the project is not far enough along in the design stage, no <br />final determination has been made as to whether pile-drivers will <br />be used during the construction phases of this project. The need <br />for pile-drivers will be determined as part of the subsequent <br />architectural and engineering design stages of the project. At <br />that time, detailed subsurface conditions, building configurations, <br />and column loading conditions will be assessed and the <br />determination of the need for pile-driving will be made. In <br />addition to driven piles, possible foundation types for various <br />structures include large concrete mat foundations, shallow spread <br />foundations, and drilled caissons. If, from an engineering <br />standpoint, the buildings can be constructed without pile-driving, <br />the applicant will endeavor to do so. However, it is probable that <br />pile-driving will be used. <br /> <br />Long-Term Traffic Noise Impacts <br /> <br />The impact of the Main Street Concourse development on land uses <br />along access roadways is assessed by determining the existing noise <br />levels along these roadways, and comparing these levels with the <br />noise levels that would exist with the traffic generated by the <br />completed project. The roadway with the greatest increase in <br />future noise levels is Owens Drive (west of Lawson Way), with an <br />increase of 6.3 dBA. However, this area will experience a noise <br />level increase of 4 dBA without development of the Main Street <br />Concourse due to increase in traffic levels. This means that the <br />actual noise level increase due to the project on Owens Drive will <br />be 2.3 dBA and will not exceed 65 CNEL. Increases in the noise <br /> <br />15 <br /> <br /> <br />