Laserfiche WebLink
I IP <br /> Verizon Communications-Stormwater Site Plan Everett, WA <br /> Water Quality <br /> III Despite the fact the site is currently developed, water quality is required to be provided for <br /> the new or replaced pollution generating surfaces. However, the proposed water quality <br /> facility has been sized to accommoda-te all--the pol utran-generating-and-note-pakition -- <br /> rgenerating surfaces. The areas used to calculate the size of the water quality facility are as <br /> shown in Table 5 below: <br /> II Table S <br /> Water Quality <br /> Only areas affected by development included in calculations. <br /> II Proposed <br /> SF AC <br /> _Pervious 78,745 1.80 <br /> Impervious(PGIS & NPGIS) 318,504 7.32 <br /> rTOTAL 397,249 9.12 <br /> To satisfy the project's water quality requirements, a pre-settling chamber and a Contech <br /> II To <br /> Vault will be installed. A flow splitter will also be installed to allow higher <br /> flow events to bypass these structures. <br /> 111 7raiit108pstn5x <br /> Basin Data j PCN Cale I PTC Calc I DO-CN Cale I DCI-TC Calc Compute Runoff for Design Event I <br /> r - I <br /> Select Design Event IWQ�" � ele <br /> AMCIII for this Computation: Protect AMC;2 <br /> r AMC1 ,: AMC2 " AMC3 <br /> i <br /> 111 Static <br /> Peak Rate: 1 5458 cfs t"s' <br /> Time to Peak 480.00 min(8 00 hrs) 1 ,. ! "` <br /> to <br /> Hydrograph Vol: 24515 69 cf(0.5628 acft( ...- <br /> =>Computaron is*I-99 9976%of theoretical for lime step of 10 00 min <br /> .-----'''''''-';) d 0"C(4 ro,l'. <br /> _I <br /> j <br /> 3 ...--, Ci/ a* fr <br /> Gate ! �• ( 1t-" <br /> 4)-1, <br /> 11-1 rr� <br /> p SBUH methodology and the StormShed software wer used to calculate the site discharge i 'r <br /> and to size the proposed water quality facility. e a fl for the 6-month, 24-hour event, < !� <br /> per the City of Everett Stormwater Manual, is inches. The'6-month, 24-hour (water <br /> %I quality) event for the fully developed (9.12 acres) site is approximately 1.55 CFS and <br /> 24,516 CF of water volume. In order to properly treat this quantity of stormwater, the <br /> following calculation was used to determine the required number of cartridges and the <br /> size of the Contech StormFilter Vault. <br /> i. <br /> 1.5458 CFS 7.48 Gallon 60 Seconds <br /> X =695 GPM <br /> Seconds 1 CF 1 Minute <br /> 1 <br /> i'ACLAND Job# 50183001 Page 21 <br />