SBUH Calculation Worksheet for City of Eugene Storm EventsProject Name: BraewoodDate: 8/28/2025Designer: ALBBasin: Swale 1 (Basins L1, L2, L3, S1, and S2)User-Supplied DataPervious AreaImpervious AreaPervious Area, SF110,334139,581 Pervious Area, Acres2.533.20Pervious 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, Acres5.74Total Project Area, Square Feet249,915Recurrence IntervalWQ2-Yr5-Yr10-Yr25-Yr50-Yr100-YrPeak Flow Rate, Qpeak, cfs1.233.163.835.066.127.358.08Total Runoff Volume, V, cubic feet17,51843,67452,37968,42382,17898,099107,517Time to Peak Runoff, hours7.837.837.837.837.837.837.83Runoff HydrographImpervious Area, SFImpervious Area, AcresImpervious Area Curve Number, CNimp0.001.002.003.004.005.006.007.008.009.000 500 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