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<br />H:\ORNO\_Surface Water Management\MS4 Administration\MCM-5_Post-Construction Stormwater Management\2_Site Plan Reviews\2022\Tanager Creek - Preliminary <br />Plat\Tanager Creek_PrePlatReview_2022-02-09.docx <br /> <br />February 9, 2022 <br /> <br />City of Orono <br />Attn: Laura Oakden <br />2750 Kelley Parkway <br />Orono, MN 55356 <br /> <br />RE: Preliminary Plat Application <br /> Tanager Creek <br /> Engineering Review #1 <br /> <br /> <br />Dear Laura: <br /> <br />As requested, I have completed an engineering review of the documents submitted for the above <br />referenced project. We offer the following observations, comments, and recommendations for your <br />consideration: <br /> <br /> <br />1. One filtration basin is proposed for stormwater runoff management to meet regulatory <br />requirements. The following must be considered regarding stormwater management: <br />a. Per MCWD requirements, the proposed stormwater management system must limit <br />proposed peak runoff rates to that of existing for the 1, 10, and 100 year – 24h hour events. <br />Per NPDES requirements, the system must also treat the water quality volume, calculated <br />as 1” times the sum of new and fully reconstructed impervious surface. If infiltration is <br />prohibited as outlined by NPDES requirements, a wet sedimentation basin or filtration <br />basin may be utilized. <br />b. Per City requirements to track TMDLs and reduce loads to meet required Waste Load <br />Allocations, the calculations for Total Suspended Solids (TSS) and Total Phosphorus (TP) <br />loading must be provided. <br />c. Facilities necessary for the ultimate development (street construction, sewer, basins, etc.) <br />must be installed and the site mass-graded at the same time as street construction to ensure <br />all drainage ways, watersheds, and runoff management systems are constructed per the <br />approved Stormwater Management Plan and are sized adequately for proposed <br />improvements. <br />d. An 8’ wide bench must be provided around the basin to provide access to the outlet and for <br />basin maintenance. <br />e. Basin must be permanently vegetated prior to issuance of any building permits. <br />f. Native vegetation should be utilized in basins and wetland buffers. <br />2. Final Plans must include the following: <br />a. Grading, Drainage, and Erosion Control Plan <br />b. Street Construction Plan <br />c. Utility Plan <br />d. Landscape and Restoration Plan <br />e. SWPPP meeting NPDES requirements <br />f. City Standard Details