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April 18, 2002 <br /> <br />SRFNo. 0024475 <br /> <br />Mr. Steve Jankowski, P.E. <br />Mr. Brian Olson, P.E. <br />CITY OF RAMSEY <br />15153 Nowthen Boulevard NW <br />Ramsey, Minnesota 55303 <br /> <br />SUBJECT: <br /> <br />NOISE MITIGATION ANALYSIS FOR BIRCH HILL LODGES <br /> <br />Dear Mr. Jankowski and Mr. Olson: <br /> <br />The purpose of this letter is to present our assessment of proposed noise mitigation at the Birch <br />Hill Lodges Development site located along the west side of TH 47, just south of the Sunwood <br />Estates Development. A Final Grading Plan prepared by James R. Hill Inc., dated <br />February8, 2002 shows that approximately 800 feet of th_is development borders the <br />TH 47 right-of-way. The town home development includes eight town home end units located <br />within approximately 100 feet of TH 47. <br /> <br />Previous Noise Analysis <br /> <br />SRF reviewed a draft noise analysis prepared for this site by HDR Engineering, Inc. The draft <br />letter report is dated February 6, 2002 and concludes that a seven-foot high berm constructed <br />between the town homes and TH 47 will block the line of sight from a five-foot-high receptor to <br />the roadway surface and therefore will provide adequate noise shielding for the development. <br />Predictions of noise levels were not included in the draft letter but it was concluded that the berm <br />would reduce traffic noise by approximately 9 dBA. <br /> <br />Discussion <br /> <br />While we did not perform any site-specific noise modeling for this develOpment, we believe that <br />traffic noise is likely to be similar to that predicted for the adjacent Sunwood Estates <br />Development (upper 60s dBA). Our analysis of traffic noise and recommended mitigation for <br />the Sunwood Estates Development is presented in a letter to you dated April 4, 2002. <br /> <br />A seven-foot-high berm that breaks the line of sight from a receptor to the pavement surface <br />would be effective at reducing tire noise (the dominant noise from cars and light trucks) but <br />would be considerably less effective at reducing noise originating from medium and heavy <br />trucks. The dominant noise from trucks is engine and exhaust noise which have a source height <br />of several feet above the pavement. While the percentage of cars and light trucks traveling on <br /> <br />-117- <br /> <br /> <br />