06-25-2018 Council Meeting Packet

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infiltration basin and the drainage and utility easements. HWL is covered by easement. 21. The applicant shall verify that the top berm of stormwater ponds is 2 ft. above the HWL of the pond. Berm updated. 22.The applicant shall label the safety bench on the plans. It shall be at least 10-ft wide. The pond slope cannot be greater than a 3:1 slope. Comment noted. The applicant shall label the safety bench on the plans. Safety bench label added. 23. The storm sewer system and grading in the rear yards of Lot 1-3 Block 1 should be evaluated to eliminate the middle structure and provide one EOF. The CB between Lot1 & 2 should be moved north onto Lot 2 so that it is not on the property line. This is not possible to maintain minimum slopes. 24. The applicant shall update the drainage area characteristics for Pond 100 in Appendix C. While the calculations appear to be correct, the applicant shall update all ponds in Appendix C to indicate that 1.1” of runoff is the required water quality volume for new impervious area. Included in the updated SWMP 25. The applicant shall confirm the elevations of the broad crested rectangular weir outlets of Ponds P200. Weir elevation updated in the model 26. The applicant shall verify NWLs (Pond 300, Wetland C) and 100-year HWLs (Pond 400) in Table 1. Note that infiltration basins do not have NWLs. Normal water levels verified. 27. It is highly recommended (MPCA Stormwater Manual) that pond liners be installed at wet ponds in A or B soils. The MPCA stormwater manual recommends a liner for ponds in A or B soil to maintain permanent pool. The ponds on the development intersect the water table so a liner is not necessary. The applicant shall note that proposed water quality ponds are not within a Source Water Protection Area therefore they are not required to have a liner. However, it will be the responsibility of the Developer to show that the proposed dead pool volume can be maintained after construction. 28. The applicant shall confirm that the starting elevations for the HydroCAD modeled storm pond storage start at the bottom of the pond (and not below). Specific to Ponds P200. Pond 200 starts at 901.5 and the v‐notch weir is set at 901.5. 29. On the Anoka County ditch system, there shall be consideration for beaver guards at all surface water structures Beaver guards will be discussed and confirmed with the ditch authority. • Water Supply There is an existing 12 inch diameter trunk watermain located along CSAH 14 (Main Street). The Nature’s Refuge development is proposed to be served by extending 8-inch diameter DIP watermain from an existing 8-inch diameter DIP watermain stub where Street A meets Main Street (CSAH 14), and installing 1-inch diameter Type K copper services. The City’s Comprehensive Plan requires that a 16 inch diameter trunk main be extended north/south in this area. The proposed watermain extends west and north for future connection / looping.