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Memorandum to: Thomas Zappia Confidential AttorneytClient Zappia & LeVahn Privileged Information October 17, 2008 Page 3 "4) Sound levels above the following are prohibited: • To enable comparison of the zoning code with the Minnesota Rules, the equivalent sound level in dBA was calculated from the octave band noise limits. For our purposes, the levels labeled "Along Residential Lines" are used. The equivalent sound level is 55 dBA. Results Comparison Since the L50 sound level is often referred to as the "average" sound level, without other guidance, the zoning code equivalent sound level is considered similar to the L5o. The measured L50's with and without the crushing plant operating are less than 55 dBA. DISCUSSION OF THE RESULTS As shown in the results summary, the L50 sound level reduced by about 2 dBA with the crushing plant not operating. The Lio sound level was reduced by about 1.5 dBA. The New Brighton zoning code limit is more stringent than the Minnesota Rules. The measurement results range from 7.7 to 9.8 dBA below the zoning code. In terms of sound energy, the measurement results range from about 10% to 17% of that allowed by the code. TA0980\06\Sound Survey Report Memo.doc Along Along Octave Band Residential Nonresidential Cycles per Line Levels Line Levels Second in Decibels in Decibels 0 to 75 72 79 75 to 150 67 74 150 to 300 66 300 to 600 52 59 600 to 1200 46 53 1200 to 2400 40 47 2400 to 4800 34 41 Over 4800 32 39 Sound levels shall be measured by equipment meeting the specifications of the American Standards Association." beginning in the 1970's. Many of the technical terms used in the zoning code have been changed Since about the same time, The American Standards Association has been known as the American National Standards Institute. • To enable comparison of the zoning code with the Minnesota Rules, the equivalent sound level in dBA was calculated from the octave band noise limits. For our purposes, the levels labeled "Along Residential Lines" are used. The equivalent sound level is 55 dBA. Results Comparison Since the L50 sound level is often referred to as the "average" sound level, without other guidance, the zoning code equivalent sound level is considered similar to the L5o. The measured L50's with and without the crushing plant operating are less than 55 dBA. DISCUSSION OF THE RESULTS As shown in the results summary, the L50 sound level reduced by about 2 dBA with the crushing plant not operating. The Lio sound level was reduced by about 1.5 dBA. The New Brighton zoning code limit is more stringent than the Minnesota Rules. The measurement results range from 7.7 to 9.8 dBA below the zoning code. In terms of sound energy, the measurement results range from about 10% to 17% of that allowed by the code. TA0980\06\Sound Survey Report Memo.doc