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<br />Tiller Corporation Elk River and Livonia Quarries <br /> <br />Noise Assessment <br /> <br />however, that with appropriate shielding, the sound level could be kept below the L50 50 dBA <br />nighttime limit. The levels were well below the daytime L50 60 dBA limit. Reading #16 at the <br />Trail site (after shutdown) represents the ambient or background sound and suggests that the shale <br />jig and wash plant increased the sound level by only 7 dBA. <br /> <br />Readings #2 and #3 near the Spencer residence were above the modeled levels and were <br />dominated by traffic noise from TH 169 but were still below the daytime and nighttime noise <br />standard, except for an L50 52 reading at the continuous monitor. The modeled road noise level <br />was higher than the observed level due to limited information on road elevation, topography east <br />of TH 169 and actual traffic volumes. The table shows that mining levels were below ambient <br />levels and had little impact on levels at the Spencer site since later readings (#11 and #12 and the <br />post-shutdown reading at 17:50 were essentially unchanged from the earlier readings. This same <br />conclusion can be drawn for readings at the NE comer of the Livonia property (readings #8, #13 <br />and #14) since the pre- and post-shutdown values were essentially the same. <br /> <br />At the south home site readings were taken after shutdown (# 17 and #2 (1/3 octave)) and it was <br />not possible to accurately model levels since, while the crushing complex was not operating, <br />some loaders or other mobile equipment not visible from the monitoring site were still operating. <br /> <br />David Braslau Associates, Inc. <br /> <br />Page 12 <br />