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1 3.4 Noise 3.4 Noise 3.4.1 Introduction The project facility is the Munn and Perkins aggregate quarry and plant located just south of East J River Road and west of Burwood Road,approximately 10 miles east of State Route 99(SR 99),south of the community of Escalon in San Joaquin County,California. Please see Figure 3.4-1 below. E The project proposes an amendment of Use Permit QX 89-2 to allow operation of the facility's asphalt plant,scale house,loaders,water trucks,and up to.125 haul truck operations during nighttime hours without authorization from the County. Currently,all facility operations are permitted to operate between the hours of 5 a.m.to 9 p.m.with operations outside of these hours permitted by County staff on a case-by-case basis.For the purposes of this analysis,daytime and nighttime hours will be considered 5 a.m.to 9 p.m. and 9 p.m. to 5 a.m., respectively. Existing residences along East River Road and Burwood Road in the vicinity of the plant/quarry ! and haul routes(see Figure 3.4-1)may be affected by increased noise exposure associated with the proposed nighttime operations.The following is supported by the environmental noise assessments completed by Bollard Acoustical Consultants, Inc.(BAC) dated August 18,2010,the peer review Fit of the BAC report b J.C. Brennan&Associates dated October 13 2010, and the peer review P Y � response memo by BAC dated October 22,2010. 3.4.1 Setting Fundamentals of Sound Noise is often described as unwanted sound. Sound is defined as any pressure variation in air that human hearing can detect. Sound,traveling thru the air as waves, creates sound pressure level offsets relative to ambient air pressure. The number of sound pressure peaks travelling past a given point in a single second is referred to C - as the frequency, expressed in cycles per second or Hertz(Hz).A given sound may consist of energy at a single frequency(pure tone)or in many frequencies over a broad frequency range.Human hearing is generally affected by sound frequencies between 20 Hz and 20,000 Hz. (20 kHz). F Another characteristic of sound is its amplitude.This refers to the magnitude of the sound pressure, intensity, or power. Sound pressure variation related to human hearing generally ranges from 20 i micropascals(µPa)to 100 Pa(100,000,000µPa).In this case 20µFa represents the assumed threshold "- of human hearing and 100 Pa represent the threshold of pain in human hearing. The ratio of these r extremes is 5,000,000 to 1.To address this large range of numbers, and to better account for the logarithmic response of human hearing, the logarithm of the sound pressure relative to the reference/threshold(20 µPa)pressure is used to derive the sound pressure level in decibels(dB). This application produces a decibel scale of 0 dB (20µPa)to 130 dB (100 Pa). r� � r E Munn R Perkins Quarry Excavation Permit 3.4-1 ESA 1211D86 Draft E1 R Apni 2011 - r