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`� so��.�NEsoT9y�F <br />� � <br />Qo <br />5 <br />pp Tppt� <br />Minnesota Department of Transportation <br />Metropolitan District <br />1500 West County Road B-2 <br />Roseville, MN 55113 <br />October 10, 2011 <br />James Tolaas <br />Director of Public Works/County'Engineer <br />Ramsey County Public Works <br />1425 Paul Kirkwold Dr. <br />Arden Hills, MN 55112 <br />RE: TH 10/CSAH 96 NOISE ANALYSIS <br />Dear Mr. Tolaas: <br />r <br />.�i', <br />� <br />Based on a meeting you had with Arden Hills Public Works Director Terry Maurer and North Area <br />Engineer Mark Lindeberg, I was asked to review and comment on the noise analyses done for TH <br />10 that affected the Lakeshore Place neighborhood and to provide information on whether different <br />heights or lengths of wall might meet the "reasonableness" threshold. <br />In 2007, Arden Hills asked MN/DOT to extend a noise analysis completed as part of the I-694 <br />Environmental Assessment (EA). In March, 2008, SEH, Inc. completed the TH 10 Barrier Study. <br />That study showed that a noise wall in the southwest quadrant of TH 10 and CSAH 96 was not <br />cost effective. A 20' high wall was analyzed and the�results showed that the wall woulcJ cost <br />$5,839 per decibel reduced per residence. A 10' high wall was also modeled and the results <br />showed that the lower wall would cost $10,875 per decibel reduced per resident. <br />A separate noise analysis was performed for the EA done by Bonestroo for the TH 10/CSAH 96 <br />interchange project, with similar, though not identical, results. The small differences in the <br />analyses are largely attributable to daily differences in noise levels when measurements were <br />taken as well as more detailed geometrics than used for the I-694 EA . This study showed that the <br />cost per decibel reduced per residence would be $7,627. <br />While the results of the finro analyses differ slightly due to studying different locations, there is a <br />significant overlap in the areas studied and the results of varying wall height and length would likely <br />yield similar results: the benefits of the wall decrease as the wall height is reduced, thus the <br />cost/benefit ratio becomes worse with a lower wall. Varying the length of #he wall will perpetuate <br />An Equal Opportunity Employer <br />