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-152- Mr. Steve JankoWski October 9, 2002 Page 2 Analyzed Noise Mitigation To assess the effectiveness of noise m~tiganon for this development, a noise barrier was modeled south of TH l0 (see attached figure). Two' heights of barrier were modeled, six and ten feet. The modeled barrier represents a solid fence or'a berm or a combination of the two. Results of Noise Analysis The results of the noise analysis are present-in the following table. Results are presented as L10 A-weighted decibels (dBA). The Lt0 descriptor indicates that the noise levels represent the noise level, that is exceeded for the loudest ten percent of' a time period or the loudest six minutes of an hour. "A" weighting approximates the way that an average person hears sounds. qoise Analysis Results 'results are Lin, A-weighted decibels or dBA) *'- t~ r) ece,.,tor No' Barrier 6-Foot Barrier 10-Foot Barrier dBA dBA Reduction dBA Reduction R1 56 54 2 53 3 R2 56 55 1 53 3 R3 53 52 1 51 2 R4 55 54 1 53- 2 State Daytime 65 65 65 Standard Noise levels at the analyzed receptors are predicted to be 53 to 56 dBA, or nine to twelve dBA below state daytime noise standards. ConstrUction of a six-foot barrier would reduce noise levels bY one to two dBA. The results of the ten-foot barrier analysis show that additional hei. ght would further reduce noise levels by another 1 to 2 'dBA. Conclusions Future traffic noise levels at 'the RJven~ick subdivision will be below state daytime noise standards. It is likely that the vacant parcel.between TH 10 and the Proposed development will be developed within a few years of construction of the Rivenwick subdivision. Any building development within the vacant parcel would serve as a noise barrier and would further reduce traffic noise levels in the Rivenwick development. Minnesota Rules Chapter 7030.0030 (Noise Control Requirement) requires municipalities to take reasonable measures to prevent the establishment of land use where noise standards would be immediately exceeded upon establishment of the land use. Based on the setting of the development ~the relatively low traffic noise levels, distance from TH 10 and likely future H:\Traffic\4616\Noise memo-jep- 10-8-02.doc ! !