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i <br />Stormwator Detention Calculation - Clty of Everett Method — (t �, <br />Perleel EngloeeMg - 2020 Colby Ave, Suite 40. Everett <br />Phone (206) 252.7233 G1, r, e <br />Project:- Alfy's PIm. 19th Street <br />Date: January 20, 1992 <br />Basle: Wood Crack 1z, <br />Total Parcel Area <br />1.20 <br />zktloF//� � <br />%Woods:E <br />% Lawnai 0.0% <br />% Earth: 92.5% <br />%Impe� 7.5% <br />0.00 <br />Design Storm (Table 1) <br />Pre -Develop 2 Yrs. <br />Post -Develop 25 YR <br />Allowable Release Rate: (Tables 2. S) <br />Woods <br />0.002 <br />cfalac. <br />Lawns <br />0.003 <br />cfs/ac. <br />Earth <br />0.601 <br />cfs/ac. <br />Impervious <br />0.936 <br />cftloc. <br />2" min. orifice Head = <br />Flow m 0.620Piv(1/12) ^ 2s(2e32.2oN) ^ (1/2) <br />-Acres <br />Proposed: <br />% Lawns: <br />% Earth: <br />%Imperv: <br />0.000 <br />0.000 <br />0.665 <br />0.006 <br />Slope: 3.3% <br />17.7% <br />0.0% <br />02.3% <br />0.00 <br />5.30 FT <br />0.25 cfs <br />TOTAL ALLOWABLE RELEASE'= 0.53 cfs = OM1 cfs/sc <br />Detention Storage Req Ircd; (Table 7) <br />Lawns 0 cmfl/a 0 <br />Earth 1010 cu.fL/sc. 0 <br />Impervious 1565 cu.M/ac. IS26 <br />TOTAL REQUIRED STORAGE = 1,526 C.F. <br />vi <br />TABLET <br />Drainage <br />Basin <br />Design Stu <br />Pre. <br />Develop <br />post. <br />Develop. <br />Combined Sewer <br />Downtown Arco <br />10 Yr. <br />50 Yr. <br />Combined Sewer <br />Outside Downl'n <br />10 Yr. <br />10 Yr. <br />Powder Mill <br />2 Yr. <br />25 Yr. <br />Pigeon Creek N2 <br />West Branch <br />2 Yr. <br />25 Yr. <br />Pigeon Creek #2 <br />East Branch <br />5 Yr. <br />25 Yr. <br />Wood Creek <br />2 Yr. <br />25 Yr. <br />Glenwood Creek <br />2Yr. <br />25 Yr. <br />North Creek <br />SYr. <br />25 Yr. <br />All other areas <br />10 Yr. <br />25 Yr. <br />Il <br />