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Mr. Rod Attebery Neumiller& Beardslee September 1, 2011 Page 5 expected to be slightly below 45 dB Leq. These modeling results are consistent with the noise measurement results described in the previous section. Although the Figure C data represents modeled results, and actual noise levels can be expected to vary depending on atmospheric conditions, the Figure C contours support the noise measurement results and BAC's conclusions that asphalt plant noise generation is within compliance with San Joaquin County daytime and nighttime noise level standards at the nearest residences in the project vicinity. Measurement of Vehicle Pass-by Noise Levels In addition to the measurement of on-site plant equipment at measurement Site 3 (Figure A), BAC also conducted single-event pass-by noise measurements at measurement Sites 1 and 2 (Figure A). These measurements we conducted to determine the typical sound exposure levels generated by project heavy trucks (both empty and loaded), as well as by non-project vehicles. The survey consisted of nightly monitoring (9 pm to 5 am) from August 16 through August 25, 2011, at measurement Site 2, and additional monitoring with BAC staff observations at Site 1 on the nights of August 16, 22, and 25, 2011. The monitoring was conducted using matched Larson Davis Laboratories (LDL) Model 820 precision integrating sound level meters at Sites 1 and 2. The meters were calibrated before use with an LDL Model CAL200 acoustical calibrator to ensure the accuracy of the measurements. The equipment used meets all pertinent specifications of the American National Standards Institute. Vehicle pass-by measurements were conducted by programming the noise level meters with appropriate exceedance thresholds. Specifically, any single-event which caused noise levels received at the microphone to exceed 70 dBA for a period of 5 or more seconds was logged as a separate single-event exceedance in the memory of the noise meter. On the three nights during which BAC staff conducted observations between the hours of 9 pm and 1 am, exceedance data was logged and correlated with the BAC staff observations pertaining to the vehicle or vehicles which caused the exceedance. Specifically, the type of vehicle, direction, and general observations on the speed of the vehicles were noted. According to truck logs kept by George Reed, Inc., 559 nighttime truck loads were generated during the time BAC's noise meter was in place at Site 2. Because each load represents two trips (1 trip leaving full and 1 returning empty), a total of 1,118 heavy trucks associated with the delivery of asphalt from the Munn & Perkins plant passed by BAC's noise meter during the monitoring program. However, a total of 1,928 separate exceedances were recorded by the noise monitor during this same period. This indicates that only 58% of the measured exceedances were potentially caused by Munn & Perkins-related heavy trucks. In addition, BAG staff observed several Munn & Perkins heavy truck pass-bys with noise emissions too low to trigger an exceedance, further reducing the percentage of exceedances which could have been caused by Munn & Perkins trucks.