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111 engineering <br />dynamics <br />ed incorporated <br />Thus, the noise level of a loader or track hoe working at the southern portion of the pit and 25 ft. below <br />grade level would be 36 dB(A). If both the loader and track hoe were working simultaneously at <br />maximum noise the noise level would be 39 dB(A). Now, lets move the equipment to the most northern <br />portion of the pit where the distance from the top of the mine face to the pit boundary is only 25 ft, then <br />the noise level at the pit boundary would be 53 dB(A) for one loader or track hoe, for both the level would <br />be 56 dB(A). As the pit depth increases the noise level at the pit boundary decreases accordingly. <br />Thus, the noise from the mobile equipment can be kept below 55 dB(A) providing that only the loader or <br />the back hoes are operating when at the northern face of the pit, but not both. Both the loader and back <br />hoe will be fitted with high performance mufflers such as the Donaldson, series M101158, which meets <br />all Original Equipment Manufacturer's requirements. Once the muffler are installed noise measurements <br />will be taken at 100 ft. and the dB(A) levels recorded. Acceptable performance will be if the maximum <br />engine exhaust noise level is Tess than 58 dB(A) at 100 ft. <br />D. Conveyors and Stackers <br />The conveyors and stackers will be located in the central area of the pit and initially at grade level. If all <br />six units were in operation at the same time, the total noise level would be 52 dB(A) at 100 ft. compared <br />to the 45 dB(A) noise level that would be produced by one unit. Once below grade level the noise level <br />at the pit boundary will be reduced due to the reduction provided by the mine pit. <br />E. Trammel and Vibratory Screen <br />Each of these units produce a noise level of 60 dB(A) at 100 ft. Combined, they would produce 63 dB(A) <br />at 100 ft. and must be located behind a noise barrier such as a berm when initially at grade level. Once <br />below grade level the mine face will provide noise reduction. For example, locating the trammel and <br />vibratory screen at the center of the pit and at 25 ft. below grade, the noise reduction would be 12 dB(A) <br />and the resulting noise level at the pit boundary would be less than 50 dB(A). <br />F. Other Equipment <br />All other equipment has low noise emission levels and will be below grade. <br />E.D.I. Job # C3864 <br />Page 10 of 11 <br />3925 S. Kalamath St., Englewood, Colorado 80110 • voice: 303 - 761 -4367 • fax: 303 - 761 -4379 <br />