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~~ r ~l 1 1 11 ngineering hr. Jim Barrett ~ry~y~ ~ February 13, 1995 ~nlAl l l~~ Page 5 of 10 77 4) 100 feet east of the access road and one-half mile south of the quarry center, ae shown in Figure 2 (H4). The data obtained are shown in Tables 5 and 6. Table 5: Existing A-weighted Noise Survey Reeulte at Measurement Location Three Exceedance SPL dB(A) SPL dB(A) Percentile 10 PM to 7 AM 7 AM to 10 PM I'max 63 73 L10 48 48 L20 47 46 L50 45 37 L90 29 29 I'min 24 25 LeQ 45 46 Table 6: Existing A-weighted Noise Survey Reeulte at Measurement Location Four Exceedance SPL d6(A) SPL dB(A) Percentile 10 PM to 7 AM 7 AM to 10 PM Lm~ 63 74 L10 41 43 L20 37 40 L50 32 36 L90 29 28 1'min 25 26 Leq 38 45 The data in Table 5 was obtained in a low density residential area and shows generally higher noise levels than those found in Table 6. The data in Table 6 was obtained in an isolated area where the principle noise input ie from pit operation and haul truck activities. Especially interesting to note are the lack of noise level differences between daytime and nighttime readings for the data in Table 5, indicating very little noise impact by the quarry which operates during the day. 7.0 Projected Noise Levels The proposed mining process involves two general stages (site preparation and pit operation) and several phases (specific areas mined over time). Site preparation involves creation of utility buildings, scale, access roads, and removing 4 to 16 feet of top soil from quarry and will occur over a relatively short period of time. Some of the top soil will be used to form 30 foot berme around the operation areas. once berme are in place, noise levels will be significantly reduced. In addition, the quarry operation will proceed downward (18 to 24 feet), increasing the effective berm height to ae much as 60 to 70 feet, further reducing noise levels.