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~~ 1 ~J I~ J ngineering Mr. Jim Barrett Pebruary 13, 1995 dynamics Page 4 of 10 I':uax ie the maximum noise level sampled during the measurement period, the L50 ie the noise level that is exceeded 50 percent of the time (similar to class average), and the L90 ie the noise level that is exceeded 90 percent of the time. The LeQ ie the noise energy level averaged over the measurement period, or the equivalent constant noise level that ie equal to the average of all the noise levels sampled over the measurement period. The noise monitor will record all noises and does not discern the distance of the noise source. Consequently, a bird, coyote, or cow creating noise near the monitor ie recorded as a relatively loud noise. Table 3: Existing A-weighted Noise Survey Reeulte at Measurement Location One Exceedence SPL dB(A) SPL de(A) Percentile 10 PM to 7 AM 7 AM to 10 PM Lm~ 50 67 L10 33 43 L20 29 40 L50 24 33 L90 21 26 Lmin 21 22 Leq 30 41 Table 4: Existing A-weighted Noise Survey Reeulte at Measurement Location Two Exceedance SPL dB(A) SPL de(A) Percentile 10 PM to 7 AM 7 AM to 10 PM Lmax 56 69 L10 32 42 L20 28 38 L50 25 36 L90 25 27 I'min 24 23 Leq 34 42 6.2 Bxisting Ditmar Quarry Bita From February 3 to February 4, 1995, EDI performed 24-hour A-weighted Statistical Noise Surveys at two locations near the existing Ditmar Quarry Bite. General Radio Model 1945 Community Noise Nonitore were used to perform the measurements. Calibration of the monitors was checked at the beginning and end of the teat period. The two measurement locations were: 3) 75 feet south of Haystack Court road and one-half mile northwest from the quarry center, as shown in Figure 2 (M3).