07-14-25 - City Council Agenda - Laserfiche WebLink

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Ms.Katie Larsen 06/04/2025 Page 2 b. Minimum freeboard requirement between EOF and proposed/existing Lowest Opening Elevations (LOE) is 1' c. Utilize current grading as-builts/plans for Watermark 5. Drainage from one lot to another requires drainage and utility easement 6. Propose future 'ghost' grading including roadway for remaining area between Erickson Property and Watermark 6th to justify temporary retaining walls and how they will be removed in the future a. Further discussion regarding retaining wall location, ownership, and future maintenance will be required b. Retaining walls exceeding 4' in height shall require a plan prepared by a Minnesota licensed structural engineer submitted for review and approval by the Building Official prior to permit issuance i. Provide fences for safety as required. 7. Driveways/Garages will need to be on the southern sides of the two most northern lots with the temporary cul de sac. • Stormwater Management Stormwater management for the Erickson Property site consists of a sedimentation basin to provide treatment. Existing and proposed discharge rates are summarized below. Pre-and Post- Development Discharge Rates (cfs) Condition 2-Year 10-Year 100-Year 10-Day Snowmelt Existing 7.36 15.00 32.57 Only needed if basins landlocked Currently 3.08 6.02 12.35 Only needed if Proposed basins landlocked Comments: 1. This development falls within the Northeast Drainage Area Comprehensive Stormwater Management Plan (CSMP) area and as such is beholden to additional rate control and volume reduction requirements. 2. The pond south of this development was constructed with the Watermark development and designed to include runoff from the Erickson Property. If rates are reduced or maintained from existing conditions, volume control provided in the form of stormwater reuse, and water quality treatment provided by the proposed pond, it is recommended to overflow the onsite pond south to the existing Pond 500 (NWL 899, HWL 904.3). This allows the proposed development to meet CSMP rate control requirements by utilizing the existing Watermark system that already meets requirements. 3. Why does PB-3 have water surface land cover modeled in HydroCAD? 4. The pond EOF must include riprap stabilization. 5. The modeled pond EOF of 906.5 does not reflect the EOF of 905.57 in the plans. 6. A detail must be provided for the pond outlet control structure. 7. The 10' aquatic bench should continue around the entire pond. If that is not feasible, the bench should at least be on the eastern side of the basin to provide a safety bench for residents. 8. Provide calculations demonstrating spread at the catchbasin low points is 10' or less for the 3-year storm event. Erickson Property Development-Engineering Review Page 227 of 240