9212 HOLLY DR 2018-01-02 MF Import

e Page 11 of 29 IAnd the water quality design storm rate (Off-line facility) will be: 1 1 1 i 1] 1 1 1 1 1 i 1 Water: Quality BMP Flow and Volume. On-line facility volume: 0.2374 acre-feet On-line facility target flow: 0.262 cfs. Adjusted for 15 min: 0.2772 cfs. Off-line facility target flow: 0.1458 cfs. Adjusted for 15 min: 0.1542 cfs. Storm Filter Sizing: Per the D.O.E. requirements for the design of stormfilters the max. allowable flow, per Stormtilter cartridge is 7.5 gallons per minute. A design flowrate of 0.1542 cfs is equal to 69.2 gallons per minute. Which requires 69.2/7.5 = 9.2 cartridges, rounded up to 10. Therefore a 6' x 12' Stormfilter vault will be selected. See the following detail. Note that the filter requires 2.3' of head from inlet to outlet to function properly. CAquawirl: Jof�eGl rtech s sized based on the targeted design flow rate of 0.15 cfs. The Vortech 0 was selected. (detail follows) Flow Splitter: The flow splitter directly upstream of the Aqua -swirl was sized to direct all storm water to the water quality facilities up to the water quality event (0 to 0.1542 cfs) after that flow is reached the splitter will direct the remaining run off directly downstream on and offsite. The splitter has an orifice that forces the water to backup in the catchbasin to a depth of 1.5 feet where the water level will be high enough to spill over a 12-inch riser and continue downstream. This design affectively takes the water quality facilities off- line after the water quality flow rate is exceeded. The orifice was sized based on a head of 1.5 feet at a flow rate of 0.1542 cfs.