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Cyphers Logistic Park AUAR 33 March 2022 iv. Stormwater – Describe the quantity and quality of stormwater runoff at the site prior to and post construction. Include the routes and receiving water bodies for runoff from the site (major downstream water bodies as well as the immediate receiving waters). Discuss any environmental effects from stormwater discharges. Describe stormwater pollution prevention plans including temporary and permanent runoff controls and potential BMP site locations to manage or treat stormwater runoff. Identify specific erosion control, sedimentation control, or stabilization measures to address soil limitations during and after project construction. AUAR Guidance: For an AUAR the following additional guidance should be followed in addition to that in EAW Guidelines: • It is expected that an AUAR will have a detailed analysis of stormwater issues • A map of the proposed stormwater management system and of the water bodies that will receive stormwater should be provided • The description of the stormwater systems would identify on-site and “regional” detention ponding and also indicate whether the various ponds will be new water bodies or converted existing ponds or wetlands. Where on-site ponds will be used but have not yet been designed, the discussion should indicate the design standards that will be followed. • If present in or adjoining the AUAR area, the following types of water bodies must be given special analyses: o Lakes: Within the Twin Cities metro area, a nutrient budget analysis must be prepared for any “priority lake” identified by the Metropolitan Council. Outside of the metro area, lakes needing a nutrient budget analysis must be determined by consultation with the MPCA and DNR staffs. o Trout streams: If stormwater discharges will enter or affect a trout stream, an evaluation of the impacts on the chemical composition and temperature regime of the stream and the consequent impacts on the trout population (and other species of concern) must be included. The existing Lake Elmo public works b uilding is located at the northeast quadrant of the Ideal Ave nue and 34th Str eet N intersection and is comprised of approximately three acres of impervious surfaces. The remainder of the existing ground cover is made up of pervious surfaces. The soil across the AUAR s tudy area is generally clayey with relatively low permeability ra tes. Valley Branch Watershed District (VBWD) regulates the stormwater management criteria for the AUAR s tudy area. For new, nonlinear developments that create 6,000 square feet or more of new impervious surface on sites without restrictions, stormwater runoff volumes will be controlled, and the post-construction runoff volume shall be retained onsite for 1.1 inches of runoff from impervious surfaces. In addition to the water quality retention requirements , the VBWD requires the peak rate of stormwater runoff from the developed site not exceed the existing peak rate of runoff for all critical duration events, up to and including the 100-year return frequency storm event for all points where discharges leave a site during all