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387 Orono Orchard Stormwater Summary <br />by Adam Parker, PE MPS 6-20-18 <br />Lot 1 Drainage Summary <br />Parcel Size <br />Greater than 2 acres (proposed will be 2 acres or more) <br />Additional Lots <br />None <br />Existing Structure on Lot <br />No, only service road, currently registered as vacant lot per Hennepin County <br />Proposed Impervious Surface including reconstructed road within parcel <br />0.25 <br />acres <br />% of Site <br />12.63% <br />Area of newly created or expanded road within parcel <br />3000 <br />sf <br />Note: Additonal Storage or Treatment Area Added but not sized at this time due to City Entrance Configuration outside of parcel (transportation access) <br />Lot 2 Drainage Summary (Stormwater Rate, Volume Required) <br />Parcel Size <br />Additional Lots <br />Greater than 2 acres (proposed will be 2 acres or more) <br />2 <br />triggers full treatment of impervious surface <br />Proposed Impervious on Lot (including existing building and driveways, roads) <br />42415 <br />sf <br />Required Treatment ( 1 inch over impervious surface) <br />3534.6 <br />cu ft <br />Treatment Credits <br />Tree Protection Areas (5% assumed over the boundaries shown on plan) <br />93.8 <br />with 5% canopy factor applied <br />Rain Garden 1 depth 992.0 - 992.90 (Surface Infiltration Basin <br />3723 <br />cu ft (fully infiltrates assuming 0.3 in/hr drawdown) <br />Total Proposed Storage <br />3816.8 <br />cu ft <br />Stormwater Rates <br />Existing <br />Proposed <br />1 -year <br />0.8 <br />0.6 <br />10 -year <br />3.2 <br />1.2 <br />100 -year <br />9.2 <br />6.2 <br />note, the RG -1 starting elevation is above infiltration volume <br />