SBUH Calculation Worksheet for City of Eugene Storm EventsProject Name: BraewoodDate: 8/28/2025Designer: ALBBasin: Swale 4User-Supplied DataPervious AreaImpervious AreaPervious Area, SF11,18116,093 Pervious Area, Acres0.260.37Pervious Area Curve Number, CNperv7698Time of Concentration, Tc, minutes5Note: minimum Tc is five minutesCity of Eugene 24-Hour Rainfall Depths (NRCS Type 1A distribution)Recurrence IntervalWQ2-Yr5-Yr10-Yr25-Yr50-Yr100-YrInches1.56 3.12 3.6 4.46 5.18 6 6.48 <br />Calculated DataTotal Project Area, Acres0.63Total Project Area, Square Feet27,273Recurrence IntervalWQ2-Yr5-Yr10-Yr25-Yr50-Yr100-YrPeak Flow Rate, Qpeak, cfs0.140.360.430.560.680.820.90Total Runoff Volume, V, cubic feet1,9934,8945,8547,6199,13010,87611,908Time to Peak Runoff, hours7.837.837.837.837.837.837.83Runoff HydrographImpervious Area, SFImpervious Area, AcresImpervious Area Curve Number, CNimp0.000.100.200.300.400.500.600.700.800.901.000 500 1000 1500 2000 2500Runoff, cfsTime, minutesWQ2-Year5-Year10-Year25-Year50-Year100-Year 800 Willamette Street, Suite 400 Eugene, OR 97401 541.684.4902 kpff.com