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<br />7A - ATTACHMENT NO.3 <br />Saltworks Proposal- Water Group Summary Report (22 January 2010) Page 40 <br /> <br />supply well located in the center of the site, citing distance and the probable occurrence <br />of the contamination in shallow groundwater, while the supply well would be screened in <br />deeper aquifers. However, there may be remaining onsite impacts to water quality from <br />decades of industrial activities onsite. In addition, other unknown release sites and <br />conduit wells may exist in adjacent areas and could serve as conduits directly impacting <br />the deeper freshwater aquifers. <br /> <br />The watershed contributing to local groundwater recharge is intensively urbanized and <br />land uses adjacent to and upgradient of the Saltworks site are largely industrial, <br />commercial, and transportation corridors, each with associated potential groundwater <br />contamination consequences. Moreover, the integrity and continuity of shallow clay <br />layers to reduce or prevent lateral or downward migration of poor quality of contaminated <br />groundwater has not been demonstrated at the site. <br /> <br />Reverse Osmosis <br />Reverse osmosis produces two streams of water. One is a high quality water that would <br />be used as the water supply and the other is a stream with a relatively high <br />concentration of salt (brine). This would create two potential issues as follows: <br /> <br />. Brine disposal- The OMB Water Supply Report indicates that brine would be <br />managed in one of the three following ways: (a) conveyed to the Cargill salt <br />production facility in Newark via Cargill's existing transbay pipeline, (b) <br />discharged directly to the Bay form an outfall located at the Saltworks site, or (c) <br />discharged into the SBSA wastewater collection system for treatment and <br />discharge as part of the SBSA's overall wastewater. The water team has not <br />evaluated the feasibility of these options, and further evaluation would be <br />appropriate as part of any further evaluation of groundwater use at the project <br />site. <br /> <br />. Additional water demand - A reverse osmosis system designed to meet average <br />production of 700 AFY of usable drinking water would need process a substantial <br />additional quantity of water to account for brine production. Or, alternatively, if <br />wells producing 700 AFY were successfully developed at the project site, some <br />of this water would not be available as water supply for the project. The amount <br />of water required for brine production would depend on system design. The water <br />team has not evaluated this further, but this would need to be considered when <br />determining the contribution of groundwater to the project's water supply. <br /> <br />Conclusions Reaardina Groundwater Qualitv <br />EKI (2006) acknowledges a variety of mechanisms and pathways for water quality <br />deterioration, concluding that the potential issues will have to be addressed during <br />detailed design review, and if wells are installed, through a comprehensive monitoring <br />program. Potential threats to onsite freshwater aquifers exist to the west, north, and <br />east of the project (seawater intrusion), overlying the freshwater aquifers (shallow brine), <br />and may even underlie freshwater aquifers. <br /> <br />If groundwater is pumped from the site, the risk of poor quality water (saltwater intrusion, <br />shallow brine, and/or deep brine) impacting deeper freshwater aquifers will need to be <br />addressed in a site-specific water resources investigation, should the applicant decide to <br />develop local groundwater resources. Additional investigations may include installation <br /> <br />33 <br />