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02/05/98 THU 16:05 FAX 6124825232 R'-MSEY CO PUBLIC WORKS ri!l002 Memorandum To: Dan Soler Bob Paine T eny Noonan From: Curtis Pratt Subject: Sound Level Measurement of Concrete Recycling at Danner. Inc. Gravel Pit in South Saint Paul Date: February 4~ 1998 Sound level measurements were made of the concrete recycling operation at the Danner, Inc. gravel pit in South Saint Paul on February 2, 1998. Equipment in operation during the sound level measurements included a Cc:darapids jaw crusher, a Cedarapids impact crusher with Scm<:ln, a Caterpillar generator, conveyor bclt;, a front end loader, and a backhoe operating ajackhammer. Sound levels were recordcd at a number oflocations and di~tances from the operation. Booause there were a number of other major sound sources in the a.rea, it was not possible to take aocurate sound level measl.lrements at greater distances than 260 feet from the operation. Sound levels were measured using a Quest Electronics M-27 Noise Logging Dosimeter. which meers ANSI SI.4-1983 Type n specification~. as required by the MPCA. The MPCA rules are written in terms of LlO and LSD sound levels. The L-EQ closely approximates the L50 under steady sound levels such as rock crusher or concrete recycling operation. Summarized in Table 1, below, are the sound level measurements recorded on February 2, 1998 of the concrete recycling operation at the Danner, Inc. gravel pit. TABLEl Sound recordinR Location Distance (ft.) L-EO Sound Level in d.BTA) West Side 50 84.2 East Side 90 79.7 South Side 130 76.5 North Side 210 75.0 South Side 260 69.9 From the above sound level measurements made at the Danner, Inc. gravel pit. projected sound levels were calculated for the closest residential receptors tD the pt'Opo:sed location of the concrete recycling operation at the Ramsey County Kent Street Site. These projec[ed sound levels are tabulated in Table 2. below. The receptors are, (A) 497