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Bremer Bank – St. Anthony July 20th, 2021 <br /> <br /> <br />2 <br /> <br />EXISTING CONDITIONS <br />The existing property was previously occupied by a furniture wholesale building but was <br />demolished between 1997 and 2003. The site currently sits vacant and is covered with <br />grass and patches of asphalt. The west drainage area consists of pine trees atop a <br />berm, as well as public sidewalk along Kenzie Terrace. This area discharges into the <br />public storm sewer in the street. The east drainage area consists of a majority of the site <br />and is mostly grass that sheet flows southeast to Coolidge Street and into the public <br />storm sewer. See Existing Drainage Map in Appendix C. <br /> <br />PROPOSED CONDITIONS <br />Proposed site improvements will include a new building and drive thru, parking area, <br />underground stormwater basin and new utilities, and landscaping. All disturbed pervious <br />areas on site will be planted or sodded. The building and parking areas (Subcatchment <br />3S) will drain into the underground stormwater basin and discharge into the public storm <br />sewer in Coolidge Street. The rest of the site’s runoff (Subcatchment 5S) will be <br />collected in the existing storm sewer along Coolidge Street. A proposed drainage area <br />map can be found in Appendix C. See Appendix D for Utility Plan and Stormwater <br />Facility Details. <br /> <br />RATE CONTROL <br />Stormwater discharges for the proposed redevelopment have been reduced to the <br />existing rates by utilizing the storage capacity in the underground systems . <br />Pretreatment will be provided by isolator rows in the system. Stormwater discharge <br />rates were computed using HydroCAD stormwater modeling software which <br />incorporates Atlas 14 24-hour rainfall distributions for Hennepin County. See Appendix <br />B for the existing and proposed HydroCAD models. The tables below summarize the <br />existing and proposed peak runoff rates from the site discharge points for various <br />precipitation events. <br /> <br />Table 1: Peak Discharge Rates <br /> <br />Storm Event <br />Existing <br />Discharge Rate <br />[cfs] <br />Proposed <br />Discharge Rate <br />[cfs] <br />1-year (2.48”) 1.47 1.43 <br />2-year (2.86”) 1.82 1.70 <br />10-year (4.26”) 3.16 3.12 <br />100-year (7.32”) 6.16 5.98 <br /> <br />The 100-yr HWL of the underground system is 907.43. The lowest floor elevation of the <br />bank is 913.00 which meets the 2’ separation requirement. <br /> <br />