Agenda Packet_2023-04-04 - Laserfiche WebLink

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PROPOSAL FOR On -Call Engineering Design Services PFAS Study PFAS Treatment Systems Our team has been involved in numerous PFAS Studies for water systems in Southern California. Our approach is to start with a site visit to each proposed well site followed by a detailed review of available record drawings. It is our understanding that the City has approximately 6 to 8 wells that will need to be considered for PFAS treatment. Once we have completed this work we would proceed with the following: ■ Obtain and review 3 to 5 years of water quality data from each well. This data will be reviewed and analyzed to confirm that the water quality is within the range required for effective PFAS treatment with IX media. is Determine if any of the wells have issues with sand, turbidity or suspended solids that would affect the 5 micron pretreatment filter and/or the IX media. ■ Prepare a comparison of each wells water quality to the pilot results in the OCWD Pilot Report. This data will be used to determine if the City wells could use the existing pilot test results or if they would require additional pilot testing be performed. in Using areal photographic mapping determine proposed layouts for each site considering both construction working room and room for future maintence including IX media change outs. ■ Determine which sites could be piped together to allow for a centralized treatment system to treat all or some of the wells. See the figure below for a typical centralized treatment system layout. CENTRALIZED TREATMENT SYSTEM WELL FIELD SYSTEM We would then work closely with the City staff to narrow down the options to 3 or 4 which include both centralized and single well treatment plants. The next step in the process would be to build a hydraulic computer model that could analyze the operations of each of the 3 to 4 options. The hydraulic computer model would include the following inputs: ■ Pump curves for all affected wells in New Pipelines from the Wells to the centralized treatment plant ■ Storage reservoirs (if required) ■ Booster Pumps (if required) ■ Existing City Distribution pipeline size and pressure where treated water will be delivered to The models are run and updated to obtain the optimum pipe diameter, pump, and motor sizing for each option. Once this is completed our team will then prepare capital and operational costs for each option. Our draft and final reports will provide the costs indicating the total capital cost, annual operating costs and the cost per acre feet of water produced. TET ouncil 19 — 42 4/4/202gage 113