Laserfiche WebLink
Preliminary Design Report Addendum No.2 <br />3.2 INTAKE STRUCTURE <br />A conceptual intake design has been developed for the proposed facility that will supply sufficient flows <br />for dry- weather and wet- weather conditions. This system consists of a dedicated intake slide gate, and a <br />dedicated 48" diameter RCP that will be located directly upstream of in- channel diversion structure. No <br />screens are provided at the inlet, as headless at the inlet would be excessive for the 100 cfs flow <br />condition, due to the limited opening area available within the 48" RCP. <br />3.3 COARSE SCREENING <br />The Bar Screening Chamber will be outfitted with a coarse screen bar rack to remove large floatables and <br />debris from the channel discharge. <br />The coarse screen will consist of one (1) manual bar screen, 6.0 feet deep and 20.0 feet wide. The bar <br />screen will have clear openings of 3.0 inches and be constructed of 0.5 inch wide by 3.0 inch deep bars. <br />The bar screen will be inclined at 15 degrees from vertical. The coarse screen is vital to the successful <br />operation of the diversion facility. Due to potential corrosive environment, galvanized steel materials are <br />considered for this design. <br />All screenings will be collected in the first chamber and excavated through the man -way openings in the <br />roof portions of the facility. Approximately 30 tons of trash is expected to be collected and because all <br />preliminary treatment will be underground and expecting low maintenance activities, a mechanical bar <br />screen will not be considered for this facility. <br />Flow after the coarse screen will be directed through a baffle wall consisting of ten (10) orifices, each 2 <br />feet high by 1 foot wide, located at the bottom of the baffle wall. The baffle wall and orifices will ensure <br />flow be distributed evenly prior to the fine screen. <br />3.4 FINE SCREENING CHAMBER <br />The sediment trap will be located downstream of the coarse screen bar rack. To effectively remove <br />sediment from the discharges, a hydraulic depth in excess of 4 feet will need to be maintained. <br />The fine screen will consist of one (1) manual bar screen, 5.0 feet deep by 20.0 feet wide. The bar screen <br />will have clear openings of 0.5 inches and be constructed of 3/8 inch wide by 2.0 inch deep bars. The bar <br />screen will be inclined 15 degrees from vertical. Stainless steel 316 materials are considered for this <br />design. <br />All screenings will be collected in the second chamber and excavated through the man -way openings in <br />the roof portions of the facility. <br />URS 9 <br />25F -141 <br />