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Minnesota Joint Application – Attachment C: Avoidance and Minimization 13620 Fenway Boulevard North – Hugo, Minnesota Carlson McCain, Inc. Page 5 employees). In addition, the proposed building and parking were placed in such a manner to be set back more than the minimum requirements set forth in the City Zoning Requirements. At the guidance of the City of Hugo, the additional set back is meant to enable additional landscape area to provide screening of the proposed training yard infrastructure. A 2-cell system (incorporating pre-treatment and utilizing the wetland for storage) was proposed by the TEP during the pre-application meeting as another alternative. The proposed ponds have a normal water level elevation of 924’. This is required to drain the parking lots and surrounding building area with minimal slope and minimal storm sewer design. The existing wetland is at an elevation of approximately 927’ which is about 3 feet higher than the stormwater management ponds. Given this existing wetland elevation and required finished floor elevation, there would be little to no water flow into the existing wetland (preventing its use of the wetland for stormwater management). A suggestion was then made to raise the building. Loucks may potentially raise the building about 2 feet to accommodate excess material onsite. With standard engineering grading practices to provide foundation drainage away from the building (per Dept. of Labor & Industry) and design 2% minimum slopes on overland flows (bituminous surfaces and green swales) the catch basin on the east side of the building could be raised to 932+/-. Subtracting 4 feet for a minimum structure build provides an invert of ~928. From there the minimum pipe slope to accommodate the flow is used, resulting in a drop of about 3 feet. The pond NWL would then be 925 – 926, which is still below the existing wetland elevation of ~927. Moving the catch basins to shorten the length of the storm sewer was also suggested; however, that would only exacerbate the issue since overland flow is 2% minimum, where pipe slope can be less than 2%, depending upon the pipe size and the quantity of flow. Therefore, in this alternative (see attached Wetland Avoidance Grading Plan) the volume that could be provided with this ponding does not meet the City runoff requirements (as shown in the table below). Proposed Plans TEP Requested Alternative Pond 1 Storage 131,585 ft3 118,645 ft3 Pond 2 Storage 75,837 ft3 86,188(1) ft3 Max Allowable Discharge(2) 1.55 ft3/s 1.55 ft3/s Actual Discharge 1.29 ft3/s 3.71 ft3/s Meets City Requirements Doesn't Meet City Requirements Notes: · (1) Pond 2 didn't change in shape, but the high water level is increased due to lack of Pond 1 volume · (2) From Pond 2 In addition, this alternative would not prevent impacts to the wetland, because it would significantly reduce or eliminate the wetland’s hydrology (due to the excavated adjacent pond 1 draining the wetland). The TEP also suggested treating only 85% of runoff stormwater runoff to allow for smaller 1st cell in the 2-cell system (which would then utilize the wetland as the 2nd cell). However, since