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Ms. Katie Larsen August 2, 2016 Page 2 K:\02988-280\Admin\Docs\Plan Review - Preliminary Plat 9. Sheet C1 – “Basin 1 Overflow” should read “Basin 1 EOF” to be consistent with the plans and modeling results. STORMWATER MANAGEMENT 1. The City will not approve stormwater management facilities located in the front yard; please relocate to the rear yards. Additional rate control could be obtained by constructing a third basin in the rear yards or by expanding the capacity of Basin 1 and/or 2. 2. Emergency overflows for Basins 1 and 2 discharge directly off site. The proposed project must not adversely affect off-site water levels, resources or private property, nor increase the potential for off-site flooding. The EOFs for Basins 1 and 2 must be redirected toward the project site or the frontage road. 3. Verify building freeboard requirements are being met: • Low floor must be a minimum of 2 feet above the 100-year high water elevation and 4 feet above the highest known groundwater elevation. • Low entry/opening must be a minimum of 1 foot higher than the EOF. 4. Lots 1 and 2 have inconsistent floor elevations compared to Sheet C1 – please verify. 5. A vegetated 10-ft bench with a 10H:1V slope should be incorporated into all ponds at the transition area between the NWL and HWL. 6. Please indicate maintenance access points for all ponds on the plans. 7. Please provide the 100-year 10-day model runoff results. 8. Verify drainage area boundaries – White Pine Road has curb and gutter and should not be entering onto the project site. 9. The MPCA recommends a dead-storage depth of at least 4-feet for NURP ponds; Basin 1 has a depth of 0.4-ft and Basin 2 has a depth of 2-ft, these ponds may not provide adequate pollutant removals and should be verified with a water quality model or designed to NURP standards. 10. Wet basins do not provide infiltration credit per RCWD rules and given the high groundwater elevations present at the site, it is unlikely that infiltration rates of 0.45 inches per hour on the basin benches would ever be achieved. Please include a discussion in the narrative how these rates will be achieved and maintained. 11. Subcatchment 4 experiences large rate increases to the southwest for all storm events. Please discuss the comment made in the Stormwater Drainage Report “no adverse impacts anticipated” for proposed Subcatchment 4.