2008-04-15_REVISION - M1980244 (336)

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d- 1MINING EQUIPMENT NOISE SOURCE INVENTORY B. 1' one-, ?1 mi'cs An inventory of the noise sources associated with mining at the proposed MLE are presented in Table 3. Key data, especially that of the Hitachi 5500 shovel and the Hitachi 4500 haul truck, was obtained by actual measurements during operation of the equipment at the CC&V mine. These data are presented in Table 3, which follows. Table 3 Mining Equipment Noise Source Invento Category Manufacturer Description dB(A) @ 100 ft. 55 dB(A) Distance 50 dB(A) Distance Rock Drills* Various Cluster of 4 81 1995 3500 Explosives Truck Various 1 65 316 562 Shovel* Hitachi 5500 81 1995 3500 Loaders CAT 992 75 1000 1780 Haul Trucks CAT 777C/95 ton it 74 891 1580 Haul Trucks* Hitachi 4500/310 ton 76 1122 1990 Dozers* CAT D-10N 76 1122 1990 Water Trucks CAT 773B 72 708 1258 Blades CAT 16G 72 708 1258 Light Power Plants Marilite 71 631 1122 Shovel and Haul Truck Hitachi 5500 4500 82.6 2300 4000 Actual measurements obtained at CM In addition to the dB(A) level at 100 ft., there are two additional columns in Table 3, which show the distances to the anticipated 50 dB(A) and 55 dB)(A) noise contours for each piece of equipment. These calculated distances are direct line-of-sight unobstructed distances and are the potential highest noise levels that would occur under calm wind conditions. During mining the Hitachi 5500 Shovel (or its equivalent) will be loading the Hitachi 4500 Haul Truck (or its equivalent) so they will be two of the loudest pieces of equipment operating in close proximity. If both units were oriented such that their direction of maximum noise output coincided, then the noise level in that direction would increase by 3 dB(A) if and only if each unit was at maximum noise output. During normal loading operations this will not occur, usually the truck is at engine idle speed and under no load. Measurements reported in the 2004 report, page 10, show a maximum noise level of 82.6 dB(A) at 100 ft. occurring when a Hitachi 5500 Shovel was loading a Hitachi 4500 Haul Truck. This is the maximum measured noise emission associated with mining and is used in assessing impact in Section IV. This maximum value of 82.6 dB(A) at 100 ft. will be used in the analysis to determine the location of the 55 dB(A) and 50 dB(A) contours as shown on the eight cross section contours presented in Appendix B. These distances, shown on the cross section, also include the reduction in noise level due to distance, intervening terrain, the approximate 30 ft. high proposed berm and a small reduction due to atmospheric absorption when the distance is greater than 3000 ft. The same or comparable mining equipment will, be used during the MLE Project. Rev # EDI Job No. C3616 Page 10 of 17 3925 S. Kalamath St., Englewood, Colorado 80110 • voice: 303-761-4367 • fax: 303-761-4379