5.5. PCSR 02-13-2007 - Laserfiche WebLink

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Tiller Corporation Elk River and Livoma Quarries Noise Assessment . 5.2.3. Elk River Wash Plant Facility The large stockpiles shielding homes west of the shale jig and wash plant will be replaced in 2007 by a lower earth berm, and addition of the cone crusher and screens will increase the overall source level. In order to maintain compliance with the nighttime sound level at the nearest homes to the west, a berm height of at least 21 feet is recommended for the central portion of the berm which lies between the process equipment and the homes. The south end of the berm could be terminated short of the property line to allow vehicle access, or an opening with overlapping berms on either side could also provide vehicle access while maintaining the effectiveness of the berm. 5.3. Estimated Sound Levels Associated with Future Operations 5.3.1. Livonia Mining Operation At the Livonia Mining Operation, the primary crusher, cone crusher and screens will eventually be located nearthe north property line of the operation, much closer to the Spencer residence. The estimated sound level at the Spencer residence for this equipment location is 49.9 dBA, just under the L50 50 dBA limit. Placement of a small berm approximately 5 feet in height along the west side of the perimeter haul road would provide additional shielding and allow compliance with the nighttime standard. . 5.3.2. Elk River Mining Operation In the future, the process equipment at the Elk River Mining Operation will be relocated to the west side of the road separating the current and future pits. With processing equipment just west of the nearest homes, a 10 foot berm will be needed along the west side of the road to enable the equipment to operate at night while complying with the nighttime noise standards. If the equipment is to operate at night in compliance with the nighttime standard without an additional berm, the equipment will have to be located at least 600 feet to the WNW of the closest approach shown in Figure 4.2. 5.3.3. Elk River Wash Plant Facility Since the equipment at the Elk River Wash Plant Facility will not change in the future, the sound levels and berm recommendations for 2007 operations will also apply to future operations at this location. 5.4. Concluding Comment The emphasis of this study was an assessment of mining noise relative to the Minnesota nighttime noise standard L50 50 dBA and recommendations to comply with this level. Since the daytime noise standard is 10 dBA higher (L50 60 dBA), compliance with the nighttime standard ensures compliance with the daytime standard. Since none of the monitored levels near the mine in 2006 or predicted level in 2007 and beyond exceeded 60 dBA, the mining operations as planned should be in compliance with the state daytime standards at the existing homes in the vicinity of the mmes. y:\jobs\2006jobs\2061 02\report\tiller _quarries_noise _ assessment.doc . David Braslau Associates, Inc. Page 20