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<br />H:\ORNO\_Surface Water Management\MS4 Administration\MCM-5\2_Site Plan Reviews\Honey Hill\Honey Hill_PrePlatReview_2_2024-06-19.docx <br /> <br />June 19, 2024 <br /> <br />City of Orono <br />Attn: Adam Edwards <br />2750 Kelley Parkway <br />Orono, MN 55356 <br /> <br />RE: Preliminary Plat Application <br /> Honey Hill <br /> Engineering Review #2 <br /> <br />Dear Adam: <br /> <br />As requested, I have completed an engineering review of the Stormwater Management Plan and Master <br />Grading Plan submitted for the above referenced project. Following are my comments for your <br />consideration: <br /> <br /> <br />1. The applicant is proposing four infiltration basins to meet stormwater runoff management <br />requirements. The following should be considered regarding the proposed system: <br />a. Proposed infiltration basins provide 1.2’ depth for Basin 1, 1.5’ for Basins 2 and 3, and 3.0’ <br />for Basin 4. The NPDES permit requires a drawdown of surface water within 48 hours for <br />infiltration basins. Based on site soils, a maximum depth of 0.8’ is allowable to meet this <br />requirement. Basins must be revised to provide the maximum allowable depth accordingly <br />or the design should be revised to include draintile and be considered filtration. <br />b. A minimum 8’ wide access bench must be provided around all basins to allow for future <br />maintenance. <br />c. A minimum 1’ separation should be provided between the surface overflows and top of <br />adjacent berms. <br />d. Proposed basins should be installed with street construction to ensure they are constructed <br />as intended. <br />e. Proposed basins should be vegetated with a native stormwater seed mix. <br />2. Consideration should be given to installing RCP for the 12” culvert proposed at approximately <br />station 3+11 in lieu of CMP to provide a longer lifecycle material. <br /> <br />If you have any questions or comments, please contact me to discuss. <br /> <br />Sincerely, <br />Bolton & Menk, Inc. <br /> <br />Robert E. Bean, Jr., P.E. <br />Senior Water Resources Project Manager <br />193