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PROPOW FOR <br />do -Call Engineering Design Services PFAS Treatment Systems <br />PFAS Study <br />Our team has been involved in numerous PEAS Studies for water systems in Southern California. ❑ur <br />approach is to start with a site visit to each proposed well site followed by a detailed review of available record <br />drawings. It is our understanding that the City has approximately 6 to 8 wells that will need to be considered <br />for WAS treatment. ❑nce we have completed this work we would proceed with the following: <br />■ Obtain and review 3 to 5 years of water quality data from each well. This data will be reviewed and <br />analyzed to confirm that the water quality is within the range required for effective PFAS treatment with <br />IX media. <br />■ Determine if any of the wells have issues with sand, turbidity or suspended solids that would affect the <br />5 micron pretreatment filter and/or the IX media. <br />■ Prepare a comparison of each wells water quality to the pilot results in the OCWD Pilot Report. This data <br />will be used to determine if the City wells could use the existing pilot test results or if they would require <br />additional pilot testing be performed. <br />■ Using areal photographic mapping determine proposed layouts for each site considering both construction <br />working room and room for future maintence including IX media change outs. <br />■ Determine which sites could be piped together to allow for a centralized treatment system to treat all or <br />some of the wells. See the figure below for a typical centralized treatment system layout. <br />CENTRALIZED TREATMENT SYSTEM <br />To <br />DISTRIBUTION <br />SYSTEM <br />We would then work closely with the City staff to narrow down the options to 3 or 4 which include both <br />centralized and single well treatment plants. The next step in the process would be to build a hydraulic <br />computer model that could analyze the operations of each of the 3 to 4 options, The hydraulic computer model <br />would include the following inputs: <br />• Pump curves for all affected wells <br />■ New Pipelines from the Wells to the centralized treatment plant <br />■ Storage reservoirs (if required) <br />■ Booster Pumps (if required) <br />■ Existing City Distribution pipeline size and pressure where treated water will be delivered to <br />The models are run and updated to obtain the optimum pipe diameter, pump, and motor sizing for each <br />option. Once this is completed our team will then prepare capital and operational costs for each option. Our <br />draft and final reports will provide the costs indicating the total capital cost, annual operating costs and the cost <br />per acre feet of water produced. <br />TETRA TECH Page 113 <br />