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. � <br />02/05/98 TFiL? 16:05 F.�X 6121825232 R:��ISE� CO PUBLIC WORKS �002 <br />Memorandum <br />To: Dan Solcr <br />Bob Paine <br />Terry Noa�nan <br />From: Curtis Pratt <br />Subject: Sound Levell�Ieasurement of Concrete Recycling <br />at Danner, Inc. Gravel Pit in South Saint Paul <br />Date: February 4, 1998 <br />Sound lcvel measurcmcnts were maci� of the concrete recycling operation at the Danner, <br />Inc. gra�el pit in South Saint Paul on February 2, 1998. Equipment in operation during <br />the sound level measurements included a Cedarapids jaw crusher, a Cedarapids impact <br />crusher with screen, a Caterpillar generator, conv�yor belts, a front end loader, and a <br />backhoe operating a jackhammer. Sound levels were rccorded at anumber of locations <br />and distances from the operation. Because there were a number of other maj or sound <br />sources in the area, it was not possible to take accurate sound level measurements at <br />greater distances than 260 feet from the operation. <br />Sound levels were measured using a Quest Electronics M-27 Noise Logging Dosimeter, <br />which meets ANSI X4-1983 Type II specifications, as required by the MPCA. The <br />MPCA rules are written in terms of L10 and ISO sound levels. The L-BQ closely <br />approximates the L50 under steady sound levels such as rock crusher or concrete <br />recycling operation. <br />Summarized in Table 1, below, are the sound level measurements recorded on February <br />2, 1998 of the concrete recycling operation atthe Danner, Inc. gravel pit, <br />TABLE 1 <br />From the above sound level measurements made at the Danner, Ync. gravel pit, projected <br />sound levels were calculated for the closest residential receptors to the proposed location <br />of the concrete recycling operation at the Ramsey County Kent Street Site. These <br />projected sound levels are tabulated in Table 2, below. The reCeptors are ,(A) 497 <br />