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<br />Tiller Corporation Elk River and Livonia Quarries <br /> <br />Noise Assessment <br /> <br />. <br /> <br />4.3. Elk River Mining Operation <br /> <br />Assumed locations of the crushing complex in 2007 (or when this area has been fully mined) and <br />the future location closest to the nearest homes are shown on Figure 4.2. The berm with peak <br />elevation of 1110 feet is shown just north of home sites 2 and 3 in the figure. The break in <br />topography presented by the road along the eastern boundary of the future mining area is <br />considered as a topographic barrier for noise from equipment in the pit. As noted in Section 2.2.2 <br />a pit floor elevation of 990 feet is assumed. <br /> <br />The L50 levels at the nearest homes have been estimated for 2007 or the most southerly location <br />of process equipment in the current mining area, and for future locations in the new mining area. <br />Predicted L50 levels from each source and the overall L50 levels at the nearest homes are shown <br />in Table 4.2. <br /> <br />Table 4.2 <br /> <br />Elk River Mining Operation Sound Levels (L50 in dBA) <br /> <br /> Time Period - 2007 <br /> Home! 43.9 Home2 50.0 Home3 49.5 <br /> Process 42.3 Process 48.6 Process 47.9 <br /> Loaders 38.9 Loaders 44.7 Loaders 44.3 <br /> Time Period - Future (with! 0 foot berm alon [J roadwav) <br /> Home! 49.0 Home2 49.9 Home3 46.0 <br />. Process 47.6 Process 48.4 Process 44.3 <br />Loaders 43.4 Loaders 44.7 Loaders 41.0 <br /> <br />Time Period - Future (600 ft from closest am roach) <br />Home! 48.4 Home2 50.6 Home3 47.2 <br />Process 47.0 Process 49.3 Process 45.7 <br />Loaders 42.7 Loaders 44.8 Loaders 41.8 <br /> <br />The predictions for 2007 assume that the process equipment is as far south as possible within the <br />current mining area. The predicted L50 level is 50.0 dBA at Home2 and 49.5 dBA at Home3. <br />Increasing the proposed berm height from 1110 to 1115 feet should keep the levels below 50 <br />dBA. For process equipment at its most southeasterly location in the new mining area, a 10 foot <br />berm along the west side of the road separating mining from the homes will be needed to keep the <br />L50 level below 50 dBA. With no additional berm, the L50 level in Table 4.2 is slightly over 50 <br />dBA with the equipment located 600 feet to WNW of the closest location (see Figure 4.2). <br />Therefore, to comply with the L50 50 dBA nighttime standard, the equipment would have to be at <br />least 600 feet from the closest approach. For 2007 and the future, sound levels will be well below <br />the L50 60 dBA daytime standard even without a berm along the west side of the road. Only <br />nighttime operations will require some additional measures. <br /> <br />. <br /> <br />David Braslau Associates, Inc. <br /> <br />Page 15 <br />