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Memorandum to: Kent Peterson Bituminous Roadways October 7, 2010 Page 4 The noise data collected from each of the four monitoring locations is provided in Table 2. The nighttime L50 values within Table 2 are based on the data collected from 6:00 am to 7:00 am at each location. The daytime L50 values presented in Table 2 is the average L50 of all hours of noise data collected from 7:00 am until 5:00 pm at each location. Table 2: Noise monitoring data at four locations near the proposed project MPCA MPCA Location Nighttime Nighttime Daytime Daytime L50 and NACt Description L50 dBA L50 Standard L50 dBA Standard #I Ind West end of Industrial Park 60.7 75 59.7 75 #2 Ind Old Dutch Railroad 66.2 75 65.9 75 #3 Res End of Eustis Court 62.5 50 62.5 60 #4 Res St. Croix St. Mid -block 58.2 50 56.3 60 (1): NAC Noise Area Classification; lnd Industrial Noise Area; Res Residential Noise Area. (2): Nighttime L50 was calculated from noise data collected between 6:00 am and 7:00 am. (3): Daytime L50 presented is the average L50 from 12 hours of noise data collected from 7:00 am to 5:00 pm. The monitored existing L50 levels from the four monitoring locations were used in conjunction with the measured noise levels at the existing Bituminous Roadways Shakopee asphalt plant to calculate the future noise levels at the noise monitoring locations. The potential future noise levels from the proposed project at each noise monitoring location were calculated using the following formula: dBAd;stance 79.4 dB(A)20 20 logro(distance /20) Once the noise Levels generated by the proposed project were determined for each noise monitoring location, these values were then added to the existing monitored noise levels to yield the predicted future noise levels. The following formula was used to calculate the summation of the existing noise with the new noise created by the proposed project: Future dBA 10 log (1 O(exlsting dsAno) I O(DB1° dB,vto) The predicted future daytime noise levels under normal plant operations are presented in Table 3 for each of the four monitoring locations. Under normal operations the noise generated by the proposed project would increase the noise levels at the four monitored locations by 0 to 0.2 dBA. An increase of this magnitude is not detectable by the human ear and supports the conclusions presented in the EAW that the proposed project would not result in a significant increase in noise in areas adjacent to the project. Figure 3 presents the existing noise levels at each location as well as the predicted future noise levels at each location with the asphalt plant under normal operation. r: o42543ihmunous RN 1 2007 RoseAire CU1.NoocMrerno.2010.I0.06.do: