Laserfiche WebLink
S"fORM',VATER SITC- FLAN <br />��� 41 c: p r. nu n t,qp�r. <br />R�TENTION/DETENTION SYSTENI <br />1lJNE 22, 2005 <br />n�r.r i� <br />The ston�� drainagc system uscd for die de��elopment consists of cullection and <br />convcyance of runoff to a wet vault `open water' cclls. Thc relcasc trom thc 'open �vater' <br />cclls thcn flows into the 'vegetatcd trcatement cell' wherc it is further trcated rmd <br />detained. Thc release from the detention vault then Oo���s to the proposed culvert at the <br />wedand corcidor. Both die bpen water' and 'vcgetated treahnent' celis also provide <br />additional `live' storvge for detention. <br />[3Ml' [tD.lS WET VAULT/TANK <br />1'hc minimum volumc of thc scdimcntation vault has becn calculatcd using thc <br />rcquirements of die CEM :�lanual with thc following cquations: <br />Q� = 6 month volumc/86,400 <br />= 3,008l86,400 = 0.0345 <br />V,,,;� = 1676.5 Qo H u5c I I= 6' <br />= 1676.5(0.0348)(6) <br />= 350 cf <br />I�he minimum ��oluma can also not be less tl�an the colume of runoff trom the 6 month <br />stonn cvent minus the "dead" storage volume in thc wet pond, sec bclo�v. <br />V,,,,� = 3,003 — 7�2 = 2,216 cf <br />Thc proposed detention vault includes a"deud" siur,ig;; ecll with thc lollo���in� <br />dimcnsions: <br />Lcngth = 36 f'cet <br />Width = 20 fect <br />Depth = 3.5 feet <br />`.Dcad" Storage Volumc = 2,520 cf <br />[3MPRD.Oi \%EGI3TATED TREATMENT CELL <br />Thc volume of' the wet pond has been calculatcd using thc requiremcnts of thc C��t <br />ManuaL Thc minimum volume can also not bc Icss than i5 percent of thc required dcad <br />stor�ge, the volume of runoff from die 6 mond� srorni event. <br />V,,,;,, = 0. I S(3,008) = 4i 1 cf <br />The "dcad" srorage volume providcd in an open celll of the detention vault that is 3G tcct <br />]ong, 1 1 fcet wide and Z fcet decp. The proposed open cell pond sturage is 792 cf. <br />BMP RD?0 EXTENDED DLTENT[JN DRY VAULT/TANK <br />The drainage design is based on the following standards. The de�clopcd onsitc runoff <br />rates will bc detained to the City o£ Gverett stmidards, Y the 2 year and matcliine the 10 <br />and 100 ycar. The lower orifice controls thc hvo year srorm event with the upper orifice <br />controlling die 10 3r 100 ycar events to meet the discharge requirements. A 334% <br />corrcction f'actor has been applied to the li��e storage portion of this vault based on the <br />�.e_ _.�,.s; a�„-o...d�,r o..,�.ocs �o ��-��-�sss �,�����ooc DWH/srm <br />