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SAN JOAQUIN COUNTY COMMUNITY DEVELOPMENT DEPARTMENT i 1810 E.a nim TON AYE.STOCK N.CA M2 GZN f��i' PHONE�Iaf,Ba1P; FA%:2091<C8J;83 May 7.2010 Mr. Paul Bullard, President Bullard Acoustical Consultants Inc. 455 Main Street,Suite 3 Newcastle.CA 95658 Re: Munn& Perkins Environmental Noise Assessment. for Increased Nighttime Operations. Dear Mr.Bollard: The Community Development Department has reviewed the above referenced Environmental Noise Assessment(ENA)for the Munn&Perkins facility on East River Road in Escalon. As you are Aware,the noise assessment request by the County is in response to Munn&Perkins Revision of Approved Actions application for expanding operating hours at the existing facility from 9:00 p.m. to 5:00 a.m.,as needed for specific nighttime paving projects.The cum;nt operating hours for the plant are restricted to the period from 5:00 a.m.to 9:00 p.m. Upon review of the ENA,the Community Development Department developed some questions/ issues regarding the assessment. Leq and Lmax The study appears to incorrectly rely on an"average Leq"and an"average Lmax"to find compliance with Development Title requirements. it should be using the Leq and Lmax without averaging. For instance,On September 28,2008,plant operations resulted in Leq that exceeded the County Nighttime standard for the hours of 10:00 pan.., 11:00 p.m.,2 a.m.,3:00 a.m.,and 6 am. Yet the"average"of the I,eq's was well below the county standard. The Lmax figures were similar. The Lcq is already a statistical "average" taken over an hour of continuous readings. The Title requires projects to stay below the Leq in any given hour.not averaged throughout the daytime or nighttinte.'fhe Lmax is the maximum single noise event,not an average of the Lmax of each hour. The definitions from the Development Title are provided below: Equivalent Sound Level(Leq)."Equivalent sound level"or"Leq'Leq"means the sound level containing the same total energy as a time-varying sound level over a given sample period, typical ly7 computed For a one(1)hour sample period. Maximum Sound Level(Lmax)."Maximum sound level"or'-Lmax"means the maximum sound level recorded during a noise event.