08-03-2020 Council work Session Packet

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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 li ne. This is not possible to maintain minimum slopes. 25. 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 26. The applicant shall confirm the elevations of the broad crested rectangular weir outlets of Ponds P200. Weir elevation updated in the model 27. 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. 28. It is highly recomme nded (MPCA Stormwater Manual) that pond liners be installed at wet po nds 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. Based on the water levels of the wetlands on-site, the dead pool volumes of the proposed ponds are assumed to be maintained post construction. 29. 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. 30. 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. 31. The applicant shall provide a design option, in coordination with RCWD, of culvert 3 that would reduce the susceptibility to being plugged by beavers. Please verify this is needed or can be something the City takes care of? This is not an engineering design standard. The ditch will be maintained by RCWD and Lake 200 will be the responsibility of the home owners association. If a Beaver prevention devise is used it would installed with the culvert and to be included in the plans. We will send the engineering information as we receive it. Plans updated with Clemson beaver pond leveler. The applicant shall send the Beaver device to the ditch authority for approval/acknowledgement. 32. The applicant shall include flumes at the west end of Street C or provide information as to how the runoff will be maintained on site.