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*:/ : 11-1 h WA <br />of vendor and haul truck events, would be negligible. Therefore, construction related traffic would not create <br />perceptible noise impacts at noise sensitive uses along nearby roads. <br />Short-term construction noise would be generated from the use of earthmoving equipment, especially during <br />the grading pbase. The nearest noise sensitive uses are the residential units bordering the Raitt Street Site to the <br />north and east, and residential units are also located to the south across Myrtle Street and west across Raitt <br />Street. Grading activities associated with the project are expected to occur over a 10-day period. There would <br />be minor earthmoving; with the assumed equipment mix including a grader, rubber -tired dozer, and <br />tractor/loader/backhoe. <br />Noise generated by onsite construction equipment is based on the type of equipment used, its location relative <br />to sensitive receptors, and the timing and duration of noise -generating activities. Each stage of construction <br />involves different kinds of equipment and has distinct noise characteristics. Noise levels from construction <br />activities are typically dominated by the loudest several pieces of equipment. The dominant equipment noise <br />source is typically the engine, although work piece noise (such as dropping of materials) can also be noticeable. <br />The noise produced at each construction stage is determined by combining the Ley contributions from each <br />piece of equipment used at a given time, while accounting for the on going timevariationsof noise emissions <br />(commonly referred to as the usage factor). Heavy equipment, such as a dozer or a loader, can have maximum, <br />short duration noise levels in excess of 80 to 85 dBA at 50 feet. However, overall noise emissions vary <br />considerably, depending on what specific activity is being performed at any given moment. Noise attenuation <br />due to distance, the number and type of equipment, and the load and power requirements to accomplish tasks <br />at each construction phase would result in different noise levels from construction activities at a given receptor. <br />Since noise from construction equipment is intermittent and diminishes at a rate of at least 6 dBA per doubling <br />of distance (conservatively ignoring other attenuation effects from air absorption, ground effects, and shielding <br />effects), the average noise levels at noise sensitive receptors could vary considerably, because mobile <br />construction equipment would move around the site with different loads and power requirements. Noise levels <br />from projectrelatedconstruction activities were calculated from the simultaneous use of all applicable <br />construction equipment at spatially averaged distances (i.e., from the acoustical center of the general <br />construction site) to the property line of the nearest receptors. Although construction may occur across the <br />entire phase area, the area around the center of construction activities best represents the potential average <br />construction related noise levels at the various sensitive receptors. <br />Based on the default CalEEMOD construction equipment mix, noise levels at various distances to nearby <br />residences were estimated for each construction phase as summarized in Table 6, Noim Levels During Construction. <br />As shown, existing noise sensitive uses surrounding the Raitt Street Site would be exposed to increased noise <br />from construction activities above existing ambient noise levels. The greatest noise impact would be generated <br />during grading phase, which is expected to occur over 10 days. Noise levels during building construction and <br />paving would result in lower noise levels and would decrease with distance at more distant receptors. <br />75C-112 <br />