Agenda - Council - 04/13/2021 - Laserfiche WebLink

Home

Riverstone South EAW January 2021 minimize noise impacts by maintaining equipment properly, including the use of mufflers and other noise controls as specified by manufacturers. Traffic Noise Riverstone South will experience some traffic noise from Highway 10, but traffic noise levels are expected fall within state noise standards. Highway noise data from the Riverstone Addition Noise Study completed in 2017 was analyzed to support this conclusion. Riverstone Addition is located across Highway 10 and roughly 875 feet north of Riverstone South. The Riverstone Addition Noise Study identified one noise receptor (i.e., one proposed home) where the modeled noise level exceeded a state standard. The noise exceedance at Riverstone Addition was a single-family home proposed in a location 335 feet from the Highway 10 right-of-way and slightly beyond end of the noise berm initially considered. Initial noise modeling assumed no measures to mitigate highway noise at that home, so the noise berm was extended to lower the noise level at that home. In Riverstone South, the nearest townhome will be 525 feet from the Highway 10 right-of-way. This distance is about 57% longer than the 335-foot distance that coincided with the noise exceedance at Riverstone Addition. As indicated by the MPCA in A Guide to Noise Control in Minnesota, distance naturally attenuates noise levels. Increasing the distance from a line noise source, like a highway, lowers the noise level by 3 dBA each time the distance is doubled. The one single-family home at Riverstone Addition that exceeded a standard had a modeled daytime L50noise level of 60.4 dBA, slightly over the daytime residential L50 standard of 60 dBA. Assuming Highway 10 traffic noise at Riverstone South is comparable to that modeled for Riverstone Addition (the projects are directly across Hwy. 10 from each other), the increased distance will lower the daytime L50 noise level at the Riverstone South townhome nearest to Highway 10 to 58.1 dBA, 1.9 dBA below the applicable daytime residential noise standard. Noise levels at Riverstone South are expected to be slightly lower than the predicted 58.1 dBA due to the following noise mitigation measures, which are expected to reduce noise levels experienced and the perception of noise from Highway 10: 1. The 30-foot buffer on the north side of Riverstone South will include a 3- to 4-foot-high undulating berm with planted conifer trees and potentially a privacy fence. 2. Residential buildings in Riverstone South will be constructed on land with elevations of 878 feet or less, making their building pads 6 feet lower than traffic lanes on the nearest stretch of Highway 10. 3. Future development of commercial/light industrial buildings on land between Highway 10 and Riverstone South will make Highway 10 less visible and less audible from Riverstone South. 29