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02/05/98 THU 16:05 FAX 6124.825232 - RAMSEY CO PUBLIC WORKS 141003 -:: '. . Wagner Street, Roseville, (B) 512 Glenwood Avenue, Roseville , (C) the Ramsey County Women's Detention Center, and (D) a new house being constructed at the southwest comer of Mackubin and La.tpenteur in Sairtt Pau1. The MPCA daytime noise standard for residential recepto:rn is L50 = 60 dB(A). The sound levels from the proposed concrete recycling operation projected for the residential recepto~ are lower than the measured weekday background sound levels, with the exception of the women's Detention Center. Projections were made assuming flat land with no obstruC:tions, The acmal sound levels experienced at the residential receptor sites should be lower due to the sound barrier effect of gravel stockpiles, berms, and vegetation. Each crushing installation is unique and no one can accurately predict the sQund lcvel of a specific crushing installation.. We would not know the actual sound Icv-=ls from our proposed concrete recycling plant until it was in operation. Also included on the tab)e are results from sound rnc:a.surcmcnts made: on January 17, 1998 during a demonstration of a NSP tub grindor; weekdAy backgrQund sound level measUfements recorded on January 30 and February 4, 1998; and the MPCA resideoual s;ound level standard. TABLE 2 Sound Source or Standard Sound Levels in dB(A) Site A Site B Site C Site D Tub Grinder (mea.5ured) 60.1 72.4 Concrete Recvclin2 (nroiected) 58.9-59.7 57 "6-~g.7 60.2-61.3 63.7-64.6 Weekday Background Sound Level 57.5-60.1 57.5-60.1 54.7 62.7-68.4 (measured) MPCA Davtime Residential Standard 60 60 60 60 MPCA noise standards are a LSO of 6CX1B(A) during daytime for a residential area. During the NSP Tub Grinder demonstration the L-EQ sound levd recorded at the closest residence, which was 340 feet north of the tub grinder, was 60.1 dB(A), This site was at a lower eJcvation than the tub grinder, which would increase the diffraction angle and therefore increase the effectiveness of sound attenuation by the benn constructed at the south edge of the tub grinder site. The L-EQ noise level recorded at the second residence, which was 520 feet north of the wb grinder and 30 feet higher than the closest residel'lce, was 72.3 dB(A). This site is at a distance of 180 feet further a.way tban site "Au but is at Ii higher elevation, at about 30 feet higher than site "A", thus reducing the diffraction angle of the sound path over the berm compared to site "A".