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02/05/98 THU 16:05 FAX 6124825232 R~MSEY CO PUBLIC WORKS I4J 002 Memorandum To: Dan Soler Bob Paine Terry Noonan From: Curtis Pratt Subject: Sound Level Measurement of Concrete Recycling at Danner, Inc. Gravel Pit in South Saint Paul Date; rebruary 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 Cedarapids jaw crusher, a Cedarapids impact crusher with screen, a CaterpiUat generator, conveyor belts, a front end loader, and a backhoe operating a jackhammer. Sound levels were recorded at a number of locations and di~tances from the operation. Because there Were a number of other major sound sources in the a.rea, it was not possible to take accurate sound level measurements at greater distances than 260 feet from the operation. Sound levels were measured using a Quest Electronics M~27 Noise Logging Dosimeter, which meets ANSI S!.4-1983 Type n specificatioM. as required by the MPCA. The MPCA rules are written in terms of LlO and 1.50 sound levels. The L-EQ closely approximates the LSO 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 recycllng operation at the Danner, Inc. gravel pit. TABLE 1 Sound recording Location Distance (ft.) L-EQ Sound Level in dB(A) 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, Ine, gravel pit, projected sound levels were calculated for the cJosest residential receptors to the proposed location of the concrete recycling operation at the Ramsey County Kent Street Site. These projected sound levels are tabulated in Table 2, below. The receptors are, (A) 497