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6. STORMWATER CONTROL PLAN <br /> A. Site Analysis <br /> Pre-Developed Site Hydrology (Disturbed Area Only) <br /> The existing site contained a recently removed SFR and paved parking/access <br /> along with walks and patio. The remainder of the existing site contains <br /> landscaping mostly lawn. The area of the SFR and pavement removed from this <br /> site has been calculated to be 0.06 ac based on aerial photos. The on-site area <br /> mostly drains to the west and northwest toward the existing alley. <br /> As per the interim Public Works Policy #2-11 the existing site will not be modeled <br /> as forested land cover but rather the existing site conditions. <br /> Using WWHM3 software the basin was analyzed for the existing flow conditions <br /> for the site. This data was then used as the matching criteria required in the <br /> sizing of the detention pipe. <br /> Site <br /> Total Site Area: 0.14 ac <br /> Hydrologic Soils Group C (Till) <br /> Impervious Area: 0.06 ac (roof& pavement) <br /> Pervious Area 0.08 ac (lawn) <br /> Existing Condition Event Output: WWMH3 <br /> Peak Flow (cfs) Area (ac) <br /> 2-yr current 0.02 0.14 <br /> 10-yr current 0.04 0.14 <br /> 100-yr current 0.065 0.14 <br /> Developed Site Hydrology <br /> For the developed site hydrology, the site areas have been calculated. based on <br /> the proposed parking and landscaping. This allowed the software to ensure this <br /> project met the runoff requirements at the connection point to the sewer main in <br /> Paine Ave. <br /> Site Basin <br /> Developed Area: 0.14 ac <br /> Hydrologic Soils Group C (Till) <br /> Impervious Area: 0.11 ac <br /> Pervious Area 0.03 ac (Landscaping) <br /> PSKC Nassau 12-0411 <br /> July 2012 Page-12 <br />