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Ms. Katie Larsen <br />06/04/2025 <br />Page 2 <br />b. Minimum freeboard requirement between EOF and proposed/existing Lowest <br />Opening Elevations (LOE) is 1' <br />c. Utilize current grading as-builts/plans for Watermark <br />5. Drainage from one lot to another requires drainage and utility easement <br />6. Propose future 'ghost' grading including roadway for remaining area between <br />Erickson Property and Watermark 6th to justify temporary retaining walls and how <br />they will be removed in the future <br />a. Further discussion regarding retaining wall location, ownership, and future <br />maintenance will be required <br />b. Retaining walls exceeding 4' in height shall require a plan prepared by a <br />Minnesota licensed structural engineer submitted for review and approval by <br />the Building Official prior to permit issuance <br />i. Provide fences for safety as required. <br />7. Driveways/Garages will need to be on the southern sides of the two most northern <br />lots with the temporary cul de sac. <br />• Stormwater Management <br />Stormwater management for the Erickson Property site consists of a sedimentation basin to <br />provide treatment. Existing and proposed discharge rates are summarized below. <br />Pre- and Post- Development Discharge Rates (cfs) <br />Condition <br />2-Year <br />10-Year <br />100-Year <br />10-Day Snowmelt <br />Only needed if <br />Existing <br />7.36 <br />15.00 <br />32.57 <br />basins landlocked <br />Currently <br />Only needed if <br />3.08 <br />6.02 <br />12.35 <br />Proposed <br />basins landlocked <br />Comments: <br />1. This development falls within the Northeast Drainage Area Comprehensive <br />Stormwater Management Plan (CSMP) area and as such is beholden to additional <br />rate control and volume reduction requirements. <br />2. The pond south of this development was constructed with the Watermark <br />development and designed to include runoff from the Erickson Property. If rates are <br />reduced or maintained from existing conditions, volume control provided in the form <br />of stormwater reuse, and water quality treatment provided by the proposed pond, it is <br />recommended to overflow the onsite pond south to the existing Pond 500 (NWL 899, <br />HWL 904.3). This allows the proposed development to meet CSMP rate control <br />requirements by utilizing the existing Watermark system that already meets <br />requirements. <br />3. Why does PB-3 have water surface land cover modeled in HydroCAD? <br />4. The pond EOF must include riprap stabilization. <br />5. The modeled pond EOF of 906.5 does not reflect the EOF of 905.57 in the plans. <br />6. A detail must be provided for the pond outlet control structure. <br />7. The 10' aquatic bench should continue around the entire pond. If that is not feasible, <br />the bench should at least be on the eastern side of the basin to provide a safety <br />bench for residents. <br />8. Provide calculations demonstrating spread at the catchbasin low points is 10' or less <br />for the 3-year storm event. <br />Erickson Property Development - Engineering Review <br />Page 32 of 46 <br />