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9610 19th Avenue SE l <br /> July 27, 2012 is <br /> Revised September 18, 2012 <br /> Page 8 <br /> Developed Condition: <br /> Pervious: 0.08 acre, CN = 86, Tc = 6.3 mins <br /> Impervious: 0.87 acre, CN = 98, Tc = 6.3 mins <br /> Note -for the flow control correction factor, it is important to note that the proposed <br /> site is 91.5-percent impervious leading to a volume correction factor of 46.5%. <br /> The pollution generating impervious surface on the site is 17,247 square feet (0.40 <br /> acre.) <br /> D. Stormwater Flow Control Plan <br /> Using the hydrologic inputs described in "B" and "C" above, the SBUH model is used <br /> to develop a flow control plan. SBUH calculates that a detention system consisting of <br /> a vault that is 52-feet long, 15-feet wide and 4.82-feet deep are required. Adjusting <br /> the length with the volume correction factor by extending the width yields a vault <br /> that is 52-feet long, 22-feet wide (15 x 1.465 = 22'). The actual depth of the vault <br /> provided is 5.03'. <br /> A 0.63-inch bottom orifice and 2.8" elbow orifice 4-feet above the bottom orifice <br /> (471.67) are required. These elements are shown on the plan. SBUH runoff <br /> calculations and system storage calculations are provided in this section. <br /> Ph: (206)403-0933, email:jayd@cleckerce.com <br />