9434 7TH AVE SE 2016-01-01 MF Import

Units 17-21 �vill have 3800 s.f. tributary to it. At 4'W x 2.5'D and 130'/100 s.f. reyuire 49 I.t'. of trench; 50 Lf. arc providcd. Correction Factor is computed from the Dcveloped Storm into the Pond ratio of Pcrvious versus Impervious (see attached drainagc map for detailed calculations). The is a 41.5% ratio of impervious to total (.59/1.42acres) and thc corrcction factor is .28. With a pond of 20 fect wide, Uic correction factor will bring the pond to 25.6' of open watcr. The pond is dcsign for 26 feet wide of open water- 13 fcet on a side. Detailcd calculations on the pond follow. "1'he G-month storm event storage requirement is 2198 c.0 of which 15% must bc associated with biological treatmcnt. Wc havc � dcsigncd a dcep ccll pond of 13' x 45' x 3' for a volume of 1755 s.f. which is 80% of the i; ! rcquircd volumc. "I'he plant sidc of the pond is sizcd at 13' x 45' x 1' or 585 c.0 for a total volumc of 2340 cJ�. which is adequatc. Nlanlings are placed bascd upon 1 pla�it per 2.25 sf of surfacc arc:a or 260 plants for t!uu 585 s.0 ot�plantcd surfacc area. i� DOWNS'I'RCAM 'fhc drainagc from thc sitc will drain to thc cxisting swalc/wcUand/stream and cross the drivc�vav lo thc south �a'hcrc it will bc tight lincd across Bvcrctt Mall Way. �