10025 19TH AVE SE BASE FILE 2018-01-02 MF Import

SWALE We will use a 100 foot long emergent swale with 12 minutes of residence time. Flow is based upon a (low of 18 gpm , n factor is 0.24, bottom width is 2 feet and sidewalls are 3:1, and slope is 1.0%. WA"CGR QUALITY "I'otal volume for the 6 month storm is 2352 c.l'. storage required. 3600 c.f. exists in the vault but the City aiso requires 15% te be in a water quality cell. The design cell has about 540 c.f. which is grcater than the 353 c.f. requircd. The pond is 2 feet deep with top n 19 x 24 and base 7'x 12' for 1 voluntc of 540 c.0 PUMI' Water will meter out of the R/D vault per the calculations pruvided. At the 2 ycar stonn evcnt thc tlow will bc approximately .Q398cfs or 18 gpm. Water quality will be provided for the 2 year storm evenL 'I'he biofiltration s�vale is sized for thc 18 plus gnllons/minutc. Within the discharge/pump chambcr, we have allowed for a 4.05 foot pump chamber till the pump ovcrflow. Pump On will be an elevation of475.00 and Pump Oft'at 472.85 elevation. This allows the pump to be completcly submerged at all times. A 2.15 foot pumping range gives a volume of about 200 gallons or a minimum pump timc of 11 minutes and a fill time of at Icast 1 1 minutes, exccpt for greuter volwne storm evenis. Dischargc elevations arc approximately 484.00 eievation. There is approximately 260 fcet of pipe and an estimated 50 feet of entrance losses for friction factor. 7'herefore: Static I lead=9.75 fr,et=484.00-474.25 (avcrage) Priction {iead is based on 310 I.f. of 1-1/4" PVC@ 14 gpm with an 1-if=3'/]00' or 930 fcet of friction head. Thc total hcad is 19.05 fect. Using a Flotect 1/2 hp FP053200A, 1/21iP, 3250A with 13.0 amps, 115v, singlc phase, 60 Hz pump results in a flow of 18-20 gpm which is close enough since the pump curve in this area was extrapolated from three kno�+�n points outside the flow rangc. Other Calculations follo��: I/