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PC: 9-6-90 <br /> QX-90-1 <br /> Noise: <br /> Noise from quarry activities would include engine and <br /> operation noise from the loader and haul trucks . An analysis <br /> of these noise generators was the basis for the determination <br /> of noise levels and contours as well as necessary mitigation. <br /> The combined noise levels from these generators would range <br /> from a low of 73 . 5 dBA (Leq) to a high of 80 dBA (Leq) at 200 <br /> feet from the source . Receptors that were used to determine <br /> noise impact were two existing residences closest to the <br /> quarry area and two locations on the residentially zoned area <br /> on the bluff to the southwest of the quarry site. Maximum <br /> worst-case noise levels at these four receptors were <br /> calculated and then compared and added to existing noise <br /> levels at the receptors which were estimated from existing <br /> highway noise contours . <br /> The resultant maximum worst-case project noise levels would <br /> increase ambient noise levels from 6 to 22 dBA at the four <br /> receptors evaluated, an increase above ambient noise levels <br /> that would be considered a significant impact if not <br /> mitigated. However, the analysis concluded that there would <br /> be potentially significant noise impacts at receptors near the <br /> site only when extraction activities take place along the <br /> boundaries of the site closest to the receptors . In the event <br /> that noise levels at the receptor sites reach the maximum <br /> allowable levels permitted by the Planning Title (Section 9- <br /> 3800 (b) ) , specific mitigation measures will be employed to <br /> reduce the noise to an acceptable level . The specific <br /> mitigation will be identified as part of an acoustical study <br /> prepared by a qualified acoustical engineer and completed <br /> prior to the initiation of extraction activities. <br /> Air Qualitv: <br /> The existing processing facility currently holds Permits to <br /> Operate (PTO ' s) from the Air Pollution Control District <br /> (APCD) . <br /> The PTO' s for the processing facility contain over 20 <br /> conditions for operation, including limits on production <br /> quantities, length of opeation, emission rates, types of fuel <br /> used at the plant, and reduction of fugitive dust. The APCD <br /> inspects the processing facility and the existing quarry on <br /> a quarterly basis and has found them to generally have been <br /> in compliance with all the permit conditions. <br /> -31- <br />