Laserfiche WebLink
L <br />BOTESCH • NASH AND ASSOCIATES • ARCHITECTS <br />4201 RUCKER BANK BUILDING • EVCRETT, WASIuNGTON 98203 • (206) 259-0868 <br />Ma "i vIff� T `" <br />city Building Inspection Department <br />SEP )a Isis <br />City of Everett cRETT <br />CITY Q(. E,, <br />City Hall Everett, Washington 9EI201 publiC Wul" U`PL <br />Attention: Mr. Ken Callahan <br />Re: Cascade High School, Alterations and Additions <br />Gentlemen: <br />The following calculations are for the Retention/Detention Systems <br />at Cascade High School. <br />RETENTION/DETENTION SYSTEM #1 at AUTO SHOP <br />post Development System #F1 <br />7,050 sq.ft. Paving <br />C = <br />450 Sidewalk <br />.95 <br />7,000 Roof Area <br />14, 5:),, sq. ft. Total <br />Pre Development System #1 <br />14,500 eq.ft. Grass Area <br />C - <br />.40 <br />Design Storm: <br />Pre Development frequency <br />1 in <br />1 in <br />10 years <br />25 years <br />Post Development frequency <br />20 minutes <br />Duration <br />Intensity Pre Development <br />1.3 <br />in./hr. <br />in./hr. <br />Intensity Post Development <br />1.6 <br />Pre Development Design Runoff: <br />(.40)(�)(12) 14,500 = .40(524) = 210 CFT <br />poet Develq mor.t Runoff: <br />(.95)(136)(1/12) 14,500 = .95(645) = 613 CFT <br />0 <br />Runoff Differential a 403 CFT <br />M <br />r1 <br />