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Ms. Katie Larsen <br />12/1 /2021 <br />Page 2 <br />The stormwater on the site flows to the south to a stormwater facility on the adjacent <br />property and eventually flows to a City of Lino Lakes pond located in Lino Park. <br />The surface water from the proposed building and parking lot will flow to several proposed <br />infiltration basins along the west, north, and east sides of the property and to a drainage <br />pond on the south side of the site. Rain guardian turrets are proposed to direct runoff to <br />the infiltration basins and the drainage pond. The infiltration basins are designed to <br />provide water quality treatment and rate control. <br />After the project is completed, the site will include new impervious surfaces including the <br />parking lot and building. <br />Based on the soil boring information, the groundwater elevation on the site is between <br />802.4 and 802.62. Soils consist of poorly graded sands and gravelly sands. <br />The applicant used a HydroCAD model based on the Atlas 14, 24-hour storms to design <br />the storm sewer conveyance system and basin. The site is designed to reduce site runoff <br />rates for the 2-, 10-, and 100-year rainfall events. <br />Pre- and Post- Development Discharge Rates (cfs) <br />Condition <br />2-Year <br />10-Year <br />100-Year <br />Pre -Development <br />0.00 <br />0.01 <br />1.04 <br />Post -Development <br />0.00 <br />0.00 <br />0.23 <br />Post -development stormwater discharge rates are less than the pre -development rates. <br />Comments: <br />1. Staff recommends Anoka County review culvert extension in the Anoka County <br />right-of-way. <br />2. Applicant to show emergency overflow elevations and locations for all facilities <br />and shall adjust contours accordingly. <br />3. Applicant to submit a Stormwater Management Plan in accordance with City <br />Ordinance 1011.011 (1). <br />4. Applicant to provide calculations showing the proposed BMP meets the water <br />quality volume requirements in Table 2 of the City's stormwater ordinance. <br />• Water Supply <br />There is existing 12-inch diameter ductile iron pipe (DIP) watermain located along Lake <br />Drive (CSAH 23) adjacent to the site. <br />The applicant is proposing a 1-inch copper water service to serve the proposed building. <br />The water service will connect into an existing stub from Lake Drive (CSAH 23). <br />Comments: <br />Precision Tune Engineering Review <br />