RDA Reso 2000-004 - Laserfiche WebLink

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Heavy-duty truck operations generate noise of about 78 dBA at a reference distance of 50 feet and a speed of 25 miles per hour. At the nearest residences, this would be attenuated to a noise level of 67 dBA due to distance (9 dBA reduction) and the existing vegetative barrier (2 dBA reduction). Without mitigation this would be a significant impact. However, the presence of the proposed earthen berm and sound wall would provide additional attenuation. The average center of noise generation for heavy-duty trucks is eight-feet (a statistical contribution average of engine height and stack height). Assuming a four foot berm with a 10 foot concrete wall, an additiona19.5 dBA of attenuation could be achieved, resulting in a noise level of 57.5 dBA (HUD, 1995). Applying a noise level of 57.5 dBA to the hours of 6:00 a.m. to 11:00 a.m. to the calculation of Ldn, results in an Ldn of 61, a one dBA increase over existing conditions. Applying the same resultant noise level to the hours of 9:00 p.m. to 12:00 a.m. would also result in an Ldn of 61. A mitigation measure is provided to ensure that the noise barrier height is sufficient to prevent a predicted increase in noise of 3 dBA or greater. Mitigation Measure 2: To ensure that acceptable operational noise levels are maintained in the project vicinity and noise conflicts between project and existing uses are avoided, the following measures should be implemented: 2(a) Noise should be considered in the designs and locations of all stationary mechanical equipment and exterior vents (e.g., equipment and vents should face away from sensitive noise receptors, vent covers should be baffled, if necessary, etc.). 2(b) The proposed trash compactor should be enclosed, or shielded by an airtight barrier on three sides (north, east, and south) to reduce the potential for nuisance noise to the nearby apartment building to the east. Alternatively, nighttime operation of the compactor could be restricted. 2(c) To reduce the potential for nuisance nighttime noise to the adjacent apartment building, mitigation for the proposed pharmacy drive-through window should include oar g of the following: - relocate the drive-through window to the west side of the building; - provide an airtight barrier on the east side of the auto queuing lane; or -limit the hours of operation from 7:00 a.m. to 10:00 p.m. 2(d) The proposed soundwall for the grocery store loading bay needs to provide S dBA reduction to avoid a 3 dBA increase in the Ldn at adjacent residences to the north for daytime deliveries. This could be achieved with a sound walUvegetative berm combination of 10 feet (i.e., 2 foot berm, eight foot wall). The wall should extend as far as possible from the loading area to the west to avoid loss of attenuation at westernmost residences. ~~