10025 9TH AVE W 2016-01-01 MF Import

DVE Consulhnp, Inc. The stage discharge ca�aulations made using the waterworks softwa�t predict a single orifice design with a riser discharge to handle overflow. The first orifice i to be 1 0" at elevation 557.15 ( 2 feet below the outlet elevationl. The nser is to be 12" in diameter a elevation 563.55. I➢EAD STORAGE AND WE'fLAND CELL In addidon to the detendon volume associated wiUt coatrolled release, there are two other functions to be built into the vault: Dead storage and Wedand treahnent Live storage is provided for in tha entire area of the vault above the dead storage and wetland waterline elevations. Total Area of pond: 1,360 sf The required desd storage is given by the volume of runoff produced by the 6 mo. , 24 hr. rainfall event for the developed conditioa From basin B i this volume is O.OII91 ac-ft, = 3,900 cf. A minimum of 15 °/a of the minimum dead storage must be associated with the wetland treahnent cell: 0.15 x 3,900 = 585 cf. This will be provided for in a second vault with dimensions 20' x 30', with area of 600 sf. Total dead storage will be provided for by over-excavating the detenrion vault by 6'. To meet city settling standards, a dead storage azea 8' wide and 60' long was selected, providing a total dead storage volume of 2,880 cf. Therefor, the total depth in the detention vault will be 3,500-2,880 = 1,020/ 600 = 1.7'. For planring purposes, depths of 1.5 to 2.5' will be used. Further, this will provide a volume in excess of the 585 cf required. Please see improvement plans for a c omplete description of the vault RELEASE AND THE DpR'NSTREAM CONDITION. Detained and treated surface runoff is conve�ed from the control structure into an existing 18" culvert along the west side of 9 Ave. T'he storm drainage systems in this area appear to be recenUy constructed and it is assumed there is adequate capacity. Drainage Report, Bush Gerdens, Job # 980Z2 C:1My Documents\DRN, REpnggO5l,docLast priMed 10/02/98 9:32 AM a