Agenda - Council - 04/13/2004 - Laserfiche WebLink

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Preliminary Plat and Site Plan Reivew Rivenwick 4th March 5, 2004, revised April 9, 2004 Page 5 of 8 submitted several sets of calculations which staff has reviewed. Staff analysis indicates that the rate of discharge from the new smaller pond will be substantially increased as a result of this development. The Lower Rum River Water Management Organization is also reviewing the calculations and has the same concerns. The LRRWMO and city storm water regulations state that there shall be no net increase in the rate of runoff from the site. The LRRWMO analysis indicates that the 100 year storm will not be contained in the ponds onsite and would spill over and run down Garnett Street. This is not acceptable. Submit Storm Sewer plans showing size and type of each pipe Submit signed plans fbr the retaining walls over 4 feet tall around the ponds. Provide details on the fencing that will be installed at the top of all walls over 3.5 feet high. This may be combined with the sound mitigation barriers as described in item 13. 12. Noise Mitigation: MnDot stated in their letter dated March 4, 2004 that municipalities should assess the noise situation and take the action deemed necessary to minimize the impact of any highway noise within the residential development. Staff engaged the services of SRF to evaluate the potential traffic noise impacts on the proposed development. SRF submitted a report that states in order to meet MPCA's daytime acceptable decibel levels, a 15 foot high barrier would need to be constructed. The noise analysis is based solely on outside decibel levels. The City Council held a work session on March 30, 2004 to discuss acceptable sound mitigation options for the proposed development. The City Council directed staff to work with SKF to offer alternative sound mitigation measures and how the alternatives coincide with MPCA's decibel standards. Tom Hillstrom from SRF submitted a revised Noise Mitigation Analysis reviewing the decibel levels when installing a 6-foot, 8- foot, or 10-fbot fence along the retaining walls. The 8 foot and 10 foot fence appear to be the most effective in reducing noise decibels. SRF also reviewed the proposed landscaping and vegetation as a means to reduce noise decibels. While the extensive vegetation will provide some. reduction in noise levels, landscaping is most effective in reducing the perception of traffic noise by removing the visual clue to annoyance in addition to increased privacy and aesthetics. 13. Traffic Generation Analysis: SKF was retained to do a traffic generation analysis for this project. This project does not have a significant impact on the regional traffic patterns. SRF was also asked to evaluate the impact of making the intersection of Riverdale Drive and Gamett Street an all way stop intersection. This will not significantly increase the travel time for vehicles using Riverdale Drive. It will provide a safe crossing for residents to go to and from Riverdale Park. Installation of the stop signs and cross walks can be made a condition of the development agreement. 14. MnDot/ Highway 10 Improvements: In their letter dated March 4, 2004, MnDot will be requiring the installation of a right turn lane eastbound along Highway 10. 15. Environmental Review: The development does not exceed the mandatory environmental review threshold and therefore no mandated environmental review is required by the State. 16. Drainage and Utility Easements: This subdivision will be served by sanitary sewer and city water, which will be extended fi'om Riverdale Drive. The entire plat will be served by gravity sanitary sewer, however it