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<br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br />1 <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br />ngineering <br />Mr. Jim Barrett /y~y~ ~~.~+ <br />Pebruary 13, 1995 ~n\Al 1 1~W <br />Page 2 of 10 // <br />4.0 Applicable Noise Lars and Ordinances <br />4.1 Mining Operations <br />The State of Colorado Noise Ordinance (25-12-103) noise limits for <br />residential and commercial areas are: <br />Table 1: Maximum Permissible Noise Levels <br />Daytime Nighttime <br />Zone 7 AM to 10 PM 10 PM to 7 AM <br />Residential 55 d8 (A) 50 dB (A) <br />Commercial 60 dB (A) 55 dB (A) <br />Paragraph 3 of Section 25-12-103 defines a penalty for loud and <br />impulsive noises, a category under which gunfire and truck Jake <br />brakes fall, of -5 d8 (A) from all the above limits. <br />4.2 Haul Truck Operations <br />The State of Colorado Noiae Ordinance (25-12-107) noise limits for <br />vehicles with a gross weight rating of 6000 pounds or more and <br />traveling at a speed of 35 mph or lees are 88 dB (A) (vehicles <br />manufactured before 1/1/73) and 86 dB (A) (vehicles manufactured <br />on or after 1/1/73) at a distance of 50 feet. <br />5.0 Noiae Levels of Bxistiag Equipment <br />Noise levels of existing equipment in use at the Ditmar Quarry were <br />measured on Thursday, December 15, 1994 between 10 AM and 12 AM with <br />atmospheric conditions that were clear, temperatures in the 40 to 50 °F <br />range, and wind speeds mostly calm (0 to 5 mph). A General Radio 1981-B <br />Sound Level Meter was used to obtain the measurements. Results of these <br />measurements are summarized in Table 2. <br />The measured data was compared to data for similar equipment in EDI's <br />data base and no descrepanciee were found. The data in Table 2 show <br />that the loudest operations/equipment are: Crusher 6 Screen (while full <br />system is operating), system loading by the 980F Cat, and backing by the <br />950F Cat. Data measured are in the form of Sound Pressure Levels <br />(SPL'9) at specific distances, then converted to Sound Power Levels <br />(PWL'e) which are independent of distance. PWL'e can then be used to <br />predict the SPL at any distance. <br />