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WSB Engineering Carwash Noise Impact Assessment <br />David Braslau Associates, Inc. Page 13 <br /> <br />6.0 PREDICTED LEVELS RELATIVE TO BACKGROUND <br /> <br />While carwash sound levels are over the Minnesota noise standards, it can be shown in Section 7 that <br />closing the carwash entry door before washing can lead to compliance. <br /> <br />This section compares carwash levels with the observed background spectrum. Figure 6.1 compares the <br />estimated carwash spectrum at receptor E5, which on the 5th floor and closest to Kenzie Terrace, with <br />measured background spectra. When there is no traffic on Kenzie Terrace (L90), the carwash sound level <br />could be as much as 20 dB above the background at some frequencies. With traffic, the carwash level is <br />still estimated to be higher, thus reducing the perceived sound level impact. <br /> <br />Figure 6.2 compares the estimated carwash spectrum at receptor A1, closest to the carwash entry. <br />Receptor A1 is further from the roadway than the background monitor and is more shielded by half of the <br />traffic noise by the Kenzington building itself. With a lower background sound level, the impact of <br />carwash noise relative to background would be much more severe. <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br />79