SBUH Calculation Worksheet for City of Eugene Storm Events <br />Project Name: DevNW Floral Hill Date: 5.13.2026 <br />Designer: ALB Basin: 1 <br />User-Supplied Data <br />Pervious Area Impervious Area <br />Pervious Area, SF 15,386 61,543 <br />Pervious Area, Acres 0.35 1.41 <br />Pervious Area Curve Number, CNperv 80 98 <br />Time of Concentration, Tc, minutes 5 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 1.4 3.12 3.6 4.46 5.18 6 6.48 <br />Calculated Data <br />Total Project Area, Acres 1.77 Total Project Area, Square Feet 76,929 <br />Recurrence Interval WQ 2-Yr 5-Yr 10-Yr 25-Yr 50-Yr 100-Yr <br />Peak Flow Rate, Qpeak, cfs 0.48 1.26 1.48 1.88 2.22 2.61 2.84 <br />Total Runoff Volume, V, cubic feet 6,366 16,529 19,464 24,776 29,261 34,398 37,416 <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, CNimp <br />0.00 <br />0.50 <br />1.00 <br />1.50 <br />2.00 <br />2.50 <br />3.00 <br />0 500 1000 1500 2000 2500Runoff, cfsTime, minutes <br />WQ <br />2-Year <br />5-Year <br />10-Year <br />25-Year <br />50-Year <br />100-Year <br /> 800 Willamette Street, Suite 400 Eugene, OR 97401 541.684.4902 kpff.com <br />APPENDIX 2