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ARDEN HILLS CITY COUNCIL WORK SESSION—APRIL 11, 2011 2 <br /> 1-4 1-694 Noise Analysis Review (continued) <br /> Councilmember Holden questioned how many receptors were used to measure the noise levels <br /> along I-694. <br /> Mr. Lindberg indicated separate readings were taken along I-694 in 2007, 2008 and again in <br /> 2010. Noise evaluations were set given the predicted elevation and placement of the new <br /> roadways. He noted the receptors were placed along the roadway to capture the sound along the <br /> roadway and then the numbers are built into the model with the new conditions. The expected <br /> noise levels are then computed by MnDOT based on the existing noise levels. <br /> Councilmember Holmes asked if the noise was louder along Highway 10 or 1-694. <br /> Mr. Lindeberg indicated this would be difficult to determine between the roadways as the noise <br /> was captured along the entire corridor and not separately. <br /> Councilmember Holden inquired why there were differing noise levels between MnDOT <br /> equipment and handheld devices. <br /> Mr. Lindeberg explained that a handheld noise meter measures noise instantaneously. MnDOT <br /> has to use an L-10 model receptor which measures noise every six minutes. This creates an <br /> average over an hour. <br /> Mayor Grant questioned if the MnDOT noise model took into account the proposed changes for <br /> County Road 96/Highway 10. <br /> Mr. Lindeberg noted this was placed into the model along with any other anticipated changes <br /> between now and 2030. <br /> Councilmember Holden asked how predictions or assumptions were made regarding the TCAAP <br /> property. Mr. Lindeberg stated MnDOT referred to the City's 30 year Comprehensive Plan to <br /> assist with these predictions. <br /> Mr. Lindeberg further reviewed the noise standard analysis with the Council. MnDOT has <br /> reviewed the decibel levels and the standard approved cost effective analysis per residence is <br /> $3,250 per decibel reduced versus $20.00 per square foot for the noise wall. <br /> City Attorney Filla questioned how MnDOT defined"per residence". <br /> Mr. Lindeberg noted the original location of the receptors calculates the sound given the number <br /> of homes assigned to the site. Only the first row of homes was calculated through the original <br /> calculations. However,the Briarknoll area did include the second row of homes. <br /> City Attorney Filla asked if the noise protection from a sound wall was verified after <br /> construction. <br /> Mr. Lindeberg noted that once the noise wall was erected, the noise analysis would cease. <br />