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TRI-VALLEY WATER AGENCIES I ESI Joint Td-Valley Potable Reuse Technical Feasibility Study <br /> ji <br /> ) <br /> + ;rs ' <br /> l' i t• '`-'4 , ,1 iiiil, • a . .� <br /> L °).f :4 A 1Ai.. .d' ce^`Ps- <br /> 0 1. <br /> is r <br /> y,,t.. _- s...,.. <br /> 0 Source Water k .. IL-N,:'' i>�. <br /> *Purification Site <br /> A End Use A <br /> Figure ES.6 Five Potential Purification Facility Locations <br /> The groundwater injection sites were identified based on proximity to treatment location, <br /> distance from production wells, potential to improve groundwater quality,and estimated <br /> transmissivity.These locations were evaluated using Zone 7's groundwater model to meet <br /> regulatory requirements for travel time to municipal wells. <br /> The COL can be used in two separate ways—as a surficial recharge for the aquifer(via Lake I)or <br /> as a holding point before delivery to DVWTP(via Cope Lake and a planned COL pipeline).Since <br /> there is an existing connection between Lake I and Cope Lake,alternatives which send water to <br /> one of the lakes can,in effect,use both lakes as potential end uses.Another potential alternative <br /> is direct delivery of purified water upstream of the DVWTP,bypassing the COL. <br /> Summary of Findings <br /> Based on the book-end approach of considering alternatives,the major findings of this study are: <br /> • Potable reuse for the Tri Valley is technically feasible.There were no fatal flaws <br /> identified by this technical evaluation. <br /> • All alternatives increase water supply reliability,with the degree of benefit varying <br /> depending on yield(5,500—10,000 AFY)and,to a limited extent,end use(e.g.,via <br /> groundwater recharge versus raw water augmentation). <br /> • All alternatives improve drinking water quality and some improve the overall <br /> groundwater basin quality. <br /> • There are good options available to site the AWPF facility. <br /> • Regulatory pathways exist for all options. <br /> • There is some variability in the overall operational flexibility and constructability <br /> depending on the option. <br /> • Cost ranges for the book-end options: <br /> o Capital costs=$103 to$222 million <br /> o Operations and Maintenance Costs=$6.5 to$9M/year <br /> o Overall unit costs=$2,200-2,500/AF <br />