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_Id_~ b _.In_........ 1313 5t#h stireet# S.s. . suite 322 · minneapolis. mn 55414 telephone: 612-331-4571 . fax: 612-3:31-4572 10 May 1996 MEMORANDUM TO: Mike Falk FROM: Dave Braslau RE: Willcoxen Residence Noise Levels - Recommendations Measured Noise Levels Noise levels were measured during the night of23-24 April 1996. One meter was set up on the deck (Meter #2) and one meter was set up in the home facing ACI (Meter #1). Two plots of data from each of these meters are provided: Lmin and Lmax and LI0 and LSO. The LIO and LSO are the most important data since these can be compared with the MPCA standards. Meter #2 on the deck showed typical LSO levels of 58 dBA which is 8 dBA over the LSO nighttime standard. Therefore, it can be assumed that a reduction of 8 dBA would be desirable. Recommendations on Fence Height Assuming typical source levels from the previous study (one potentially shielded by the existing park wall and one potentially shielded by the Willxoxen fence), the effects of a noise wall have been estimated. Currently it is estimated that neither fence provides substantial shielding of roof noise from ACI (existing levelS8 dBA). With both walls S feet above the roof height (assuming that a person on the deck is the same height as the roof), this level would drop to SO.7 dBA which would be close to the standard. However, if only the Willxocen wall were constructed to be S feet above the roof height, the level would still be SS dBA. The other homes to the west of the Willcoxen residence will also be exposed to levels of around S3 dBA without a barrier. A barrier behind these homes 4 to S feet above roof height would bring this down to SO dBA. Ideally, the entire length of wall would be S feet above roof height. Perhaps a higher wall on the could be constructed on the Willcoxen property at this time with the possibility of extending the height of the park wall if this does not appear to be satisfactory to the residents northwest of ACI. willnois.mem 96028