12/08/2021 P&Z Packet - Laserfiche WebLink

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Ms. Katie Larsen 12/1 /2021 Page 2 2 Staff reremmenrlo that a minimum olene of n 70/ he used fer roadway graded Plan revised 4. ppliEa�shall update tin e� �t GUrb 'T�Pr�P'o t curb noted where required. motes-and add tip Curb detail on_AECP eU t GUrrb detail Sheet C7 to .,lar . t notes tip out to he +inned eut at 1 " per font 6. Appl+eant shall review Rd update ditch grading a'E)Rg 24111-AveRue. The plaRS make it like the rlitGh will hold water nr-rth of the nU IVert that n c ')filth seem AveRue. • Stormwater Management The stormwater on the site flows to two different places. The southern portion of the site flows to a culvert located in the southeast corner that drains to the City of Hugo. The northern portion of the site flows to the north to an existing wetland in the northwest corner of the site. All of the stormwater from the site eventually flows to Clearwater Creek, which is an impaired water located approximately 0.4 miles south of the site. The surface water will flow to a new wet sedimentation basin. Storm sewer is proposed to collect water from the parking lot and road and then direct it to the proposed Stormwater Pond 1 OP. Some runoff will first be passed through Low Area 20P, before ultimately draining to the basin. Pond 1 OP is designed to discharge southeast to the existing ditch and culvert system. After the project is completed, the site will include approximately 2.42 acres of new impervious surfaces including the streets, parking lots, and rooftops. Groundwater elevations ranged from 908 to 912 throughout the site and no groundwater was detected where the pond is being proposed. Soils consist primarily of sandy lean clay, and clayey sand. Due to these soil types, infiltration is not feasible. The applicant used a HydroCAD model based on the Atlas 14, 24-hour storms to design the storm sewer conveyance system and basin. The site is designed to reduce site runoff rates for the 2-, 10-, 100-year rainfall events and 10-day snow melt event. Pre- and Post- Development Discharge Rates (cfs) Condition 2-Year 10- 100- 10-Day Year Year Snowmelt Pre- 4 6.8 4.2 4.2 Development Post- 4 6.3 2.2 2.2 Development Belland Farms & Associated Eye Care Partners Engineering Review