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Idyllvale Shores – SWMP October 2024 <br />Civil Methods, Inc.Page | 1 <br />1.INTRODUCTION <br />The Idyllvale Shores project includes the construction of a rural residential subdivision and <br />related infrastructure at an existing property at 215 North Arm Ln, Orono, MN 55364 (Hennepin <br />County PID 0611723240001). Five lots with new homes are planned, as well as a shared lot with <br />a walking path and two roads terminating in cul-de-sacs to serve the properties. This Stormwater <br />Management Plan (SWMP) addresses the grading and stormwater controls necessary to mitigate <br />the impacts of the project. <br />Governmental agencies with jurisdiction over drainage and stormwater for this project include: <br />·City of Orono (City) <br />·Minnehaha Creek Watershed District (MCWD) <br />·Minnesota Pollution Control Agency (MPCA) <br />Where needed, site conditions have been modeled with the HydroCAD modeling software using <br />the TR-20 methodology and Atlas 14 design rainfall amounts. <br />Applicability <br />·Project requires an NPDES/SDS Permit because more than 1 acre of soil is disturbed. <br />·Project is subject to the rules and permitting requirements of the MCWD, including but <br />not limited to: erosion control permit, wetland permit, and stormwater permit. <br />·Project is generally subject to the City of Orono rules, standards, and permitting <br />requirements. <br />Regulatory Stormwater Requirements: <br />1)An erosion and sediment control plan meeting all agency requirements and a <br />stormwater pollution prevention plan (SWPPP) meeting the requirements of the MPCA <br />construction stormwater permit must be provided. <br />2)Volume reduction practices consistent with Appendix A of the MCWD stormwater rule <br />must be installed to provide volume reduction in an amount equal one inch times the <br />area of impervious surface stated in Table 1 of the stormwater rule. <br />3)Rate control practices must be provided to prevent an increase in the peak runoff rate <br />from the site, in aggregate, for design storm events. <br />4)There must be two feet of vertical separation (freeboard) between the 100-year HWL of <br />a waterbody or stormwater practice and the low opening of any hydraulically connected <br />structure. <br />143