Laserfiche WebLink
Preliminary Design Report Addendum No.2 <br />2.2.2 Maximum Design Flow <br />Based on the PDR Addendum No. 1 (August 2013), the proposed diversion facility will have a target <br />maximum flow capacity of 100 cfs to treat the front end portion of the "first flush" flow to provide <br />adequate capacity for the entire dry- weather urban discharges and a portion of the "first- flush" stormwater <br />quality event. The "first- flush" stormwater quality event is defined as the 85" percentile discharge of <br />stormwater runoff events. <br />2.2.3 Dry- Weather Flow Diversion Operations <br />During dry- weather operations, the proposed Diversion Facility will provide primary treatment to remove <br />floating debris and sediments from Delhi Channel. The treated water will then be pumped into either the <br />golf course reservoir or the sewer system for further reuse or treatment and disposal. As such, the in- <br />channel diversion structure will remain in the closed position; the water level in the Delhi Channel <br />upstream of the diversion facility will raise and the water level will be controlled by the tailwater <br />condition in the proposed diversion facility. System hydraulics and detailed calculations are discussed in <br />Section 3. <br />The diversion facility by -pass channel will remain open during normal dry- weather operation. The water <br />level in the storage tank will be kept lower than the invert of the outlet pipe and therefore no flow will be <br />redirected back to the channel system downstream. However, if the storage tank level is raised above the <br />outlet pipe invert, water will overflow to the channel system downstream. <br />2.2.4 Wet - Weather Diversion Operations <br />During the wet - weather operations for storm water flow less than 100 cfs, the treatment process will <br />provide gross solids removal from entering into the channel system and the storm water will be re- <br />introduced into the channel system downstream. As such, the in- channel flow diversion structure will <br />remain in the closed position. A maximum of 100 cfs will be diverted to the facility. Trash and debris will <br />be removed by the coarse and fine screening portions of the facility. Upon exceeding the maximum <br />design capacity, the in- channel diversion will open, allowing the storm flow to pass. <br />The pump station will be shut down during the wet - weather operations due to concerns of deteriorated <br />water quality for reuse purpose, when only a minimal percentage (0.4 %) of flow could be reused. <br />URS 5 <br />25F -137 <br />