SBUH Calculation Worksheet for City of Eugene Storm Events <br />Project Name: Braewood Date: 8/28/2025 <br />Designer: ALB Basin: Swale 5 <br />User-Supplied Data <br />Pervious Area Impervious Area <br />Pervious Area, SF 13,897 17,092 Pervious Area, Acres 0.32 0.39 <br />Pervious Area Curve Number, CNperv 76 98 <br />Time of Concentration, Tc, minutes5 Note: minimum Tc is five minutes <br />City of Eugene 24-Hour Rainfall Depths (NRCS Type 1A distribution) <br />Recurrence Interval WQ 2-Yr 5-Yr 10-Yr 25-Yr 50-Yr 100-Yr <br />Inches 1.56 3.12 3.6 4.46 5.18 6 6.48 <br />Calculated Data <br />Total Project Area, Acres 0.71 Total Project Area, Square Feet 30,988 <br />Recurrence Interval WQ 2-Yr 5-Yr 10-Yr 25-Yr 50-Yr 100-Yr <br />Peak Flow Rate, Qpeak, cfs 0.15 0.39 0.47 0.62 0.76 0.91 1.00 <br />Total Runoff Volume, V, cubic feet 2,152 5,383 6,460 8,446 10,149 12,121 13,288 <br />Time to Peak Runoff, hours 7.83 7.83 7.83 7.83 7.83 7.83 7.83 <br />Runoff Hydrograph <br />Impervious Area, SF <br />Impervious Area, Acres <br />Impervious Area Curve Number, CNimp0.000.200.400.600.801.001.200 500 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