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Ms. Katie Larsen <br />June 6, 2018 <br />Page 5 <br /> <br /> <br /> S:\Community Development\Projects\Planning Cases\Nature's Refuge\Staff Reports\20180611 CC (RZ & PUD PP)\20180611 v2 (revised 20180608)\a2 2018060 <br />Applicant shall verify the bottom elevation, as it differs between HydroCAD model, <br />plans, and Appendix C. Verify the culvert outlet elevation; outlet should be above <br />the exfiltration elevation. As a note: planting medium is not necessary below the <br />bottom of the infiltration basin. <br />16. The applicant shall verify the retention volume calculation for Pond 400 in Appendix C <br />as there appears to be an error. The volumes are correct. <br />17. If needed, the opportunity may exist to maximize infiltration at the infiltration basin by <br />constructing the basin to minimize the separation between the bottom of the basin and <br />the water table. The basin needs minimum 3 feet separation from the water table and <br />cannot be lowered. <br />18. The applicant shall verify that the HWL of the Infiltration Basin is 2.0 feet below the <br />low entry elevations of surrounding buildings. Separation requirement is met <br />19. The applicant shall display and label emergency overflows with spot elevations and <br />drainage arrows at all ponds and sags, specifically at the intersection of Street A and <br />Street C and at the cul-de-sac of Street C. EOF’s added. <br />20. The applicant shall confirm that there is a 10-ft. setback between the HWL of the <br />infiltration basin and the drainage and utility easements. HWL is covered by easement. <br />21. The applicant shall verify that the top berm of stormwater ponds is 2 ft. above the HWL <br />of the pond. Berm updated. <br />22. The applicant shall label the safety bench on the plans. It shall be at least 10-ft wide. <br />The pond slope cannot be greater than a 3:1 slope. Comment noted. <br />The applicant shall label the safety bench on the plans. <br />23. The storm sewer system and grading in the rear yards of Lot 1-3 Block 1 should be <br />evaluated to eliminate the middle structure and provide one EOF. The CB between Lot <br />1 & 2 should be moved north onto Lot 2 so that it is not on the property line. This is not <br />possible to maintain minimum slopes. <br />24. The applicant shall update the drainage area characteristics for Pond 100 in <br />Appendix C. While the calculations appear to be correct, the applicant shall update <br />all ponds in Appendix C to indicate that 1.1” of runoff is the required water quality <br />volume for new impervious area. <br />25. The applicant shall confirm the elevations of the broad crested rectangular weir <br />outlets of Ponds P200. <br />26. The applicant shall verify NWLs (Pond 300, Wetland C) and 100-year HWLs <br />(Pond 400) in Table 1. Note that infiltration basins do not have NWLs. <br />27. It is highly recommended (MPCA Stormwater Manual) that pond liners be <br />installed at wet ponds in A or B soils. <br />28. The applicant shall confirm that the starting elevations for the HydroCAD modeled <br />storm pond storage start at the bottom of the pond (and not below). Specific to <br />Ponds P200. <br />29. On the Anoka County ditch system, there shall be consideration for beaver guards <br />at all surface water structures. <br /> <br /> Water Supply <br /> <br />There is an existing 12 inch diameter trunk watermain located along CSAH 14 (Main <br />Street). The Nature’s Refuge development is proposed to be served by extending 8-inch <br />diameter DIP watermain from an existing 8-inch diameter DIP watermain stub where Street