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<br />----- <br />Tiller Corporation Elk River and Livonia Quarries Noise Assessment <br />Table 3.2 Assumed Sound Level Spectra for Mine Sources (dB at 100 feet) <br /> Octave Band Freauencv (Hz) <br />Source 32 63 125 250 500 1000 2000 4000 8000 dBA <br />Livonia Primary 81.2 81.5 83.6 78.9 74.7 72.2 69.0 62.3 52.8 77.8 <br />Livonia Twin Screens 75.3 73.4 78.1 72.8 75.4 77.9 71.9 65.3 59.8 80.3 <br />Elk River processing 79.3 80.2 79.0 78.2 79.2 79.0 74.7 65.1 50.7 82.4 <br />Elk River Shale <br />jig/wash plant 81.4 77.5 82.9 70.8 77.4 71.8 68.0 61.7 57.4 77.7 <br />Loader 79.9 74.2 82.7 78.3 73.4 66.6 70.0 62.0 43.2 76.4 <br />3.2. Comparison of Monitored and Modeled Levels <br />Sound levels at the monitoring sites were also modeled using the source levels in Table 3.2 and <br />the location of mining activity. Locations of monitoring sites and process equipment in 2006 <br />when readings were taken are shown in Figure 2.1, Figure 2.3, and Figure 2.5. The modeling <br />methodology for theoretical prediction of sound levels is discussed in Section 4.0. <br />Table 3.3 compares the monitored and modeled L50 sound levels at each of the affected <br />monitoring sites. Modeled levels refer to an outdoor propagation model for point sources while <br />Road Model refers to predictions using the MinnNoise highway noise model, based upon <br />estimated traffic volumes from the MnDOT traffic flow map for TH 169, and simplified geometry <br />assumptions. Predictions by this model were divided into off-peak (readings #2 and #3 taken <br />close to 3 pm) and other readings taken at 4 pm and later. <br />Table 3.3 Predicted Crusher Complex Sound Levels (dBA) <br />Reading Time Location Road <br /> eEL 593 LD 700 Modeled Model <br />Octave <br /> 1 14:34 Trail site 45.1 44 62.6 <br /> 2 15:15 Spencer site 47.1 52 44.2 59.6 <br /> 3 15:16 Spencer site 49.7 52 44.2 59.6 <br /> 8 15:53 NE corner of mine 64.8 55.7 67.9 <br /> 11 16:44 Spencer site 51.6 44.2 62.6 <br /> 12 16:45 Spencer site 49.2 44.2 62.6 <br /> 13 17:03 NE corner (shutdown) 65.2 70.9 <br /> 14 17:13 NE corner (shutdown) 67.3 70.9 <br /> 15 17:25 Spencer site (shutdown) 47.4 50 62.6 <br /> 16 17:50 Trail site (shutdown) 37.8 37 <br /> 17 18:13 South home site (shutdown) 48.0 68.7 <br />1/3 Octave <br /> 1 14:39 Trail site 46.3 <br /> 2 18: 15 South home site (shutdown) 46.7 <br />For readings #1 and #1 (1/3 Octave), the modeled level was well above the monitored level, <br />which is attributed to insufficient shielding assumed by the stockpiles. The data did demonstrate, <br />David Braslau Associates, Inc. Page 11 <br />