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<br /> <br />December 23,2004 <br /> <br />Memo to: <br /> <br />The File <br /> <br />From: <br /> <br />Scott Spisak <br /> <br />Re: Pavement Recycle Crushing Noise Monitoring <br /> <br />On November 30,2004, we engaged American Engineering testing, Inc. (A.E.T.) to <br />perform noise monitoring ofIntex Corporation's crushing equipment that was recycling <br />pavement at our Johnson Pit at 12500 Rich Valley Blvd. In Rosemount. The monitoring <br />was perfoffi1ed on December 2, 2004. <br /> <br />There were no other operations being conducted on the property that day. Intex <br />equipment included a CAT 988F wheel loader, a jaw type primary cmsher, a cone type <br />secondary crusher with vibratory screens, a trailer enclosed diesel generator and several <br />belt conveyors to transfer material from the primary crusher, through the secondary <br />crusher and onto the stockpile. <br /> <br />The monitoring accounted for the "worst case", that being downwind from the secondary <br />crusher and generator with no obstructions or vegetation to mitigate the sound. <br /> <br />The test results (see report attached) indicate that under similar severe conditions we <br />would meet the MPCA Noise Classification Level 3 (Industrial & Manufacturing <br />Category) Daytime LI0 and L50 requirements at a distance of250 feet from the <br />operation. Using the MPCA's "A guide to Noise Control in Minnesota" for the same <br />conditions, we can estimate the decibel level at further distances. The test results indicate <br />that the crushing equipment behaves like a point source where doubling a given distance <br />from the source results in a 6 decibel drop in noise levels. <br /> <br />Using this method, we would meet the MPCA Noise Classification Level 2 (Retail, <br />Business, Parks category) between a distance of 600 and 800 feet from the operation. We <br />would meet the MPCA Noise Classification Levell (residential) requirements between <br />1000 and 1200 feet from the operation. <br /> <br />Of course few if any sites would have 600 to 1200 feet of clear, unimpeded sight line <br />distance in a downwind direction from this type of operation. Urban areas in particular, <br />would have obstructions such as buildings or stands of trees that would deflect, absorb or <br /> <br />