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FINAL DRAFT PRELIMINARY REPORT (Connections to EOCF #2) 2. POTENTIAL AVAILABLE GROUNDWATER SUPPLY 2.1 Water Supply Summary Tetra Tech met with the cities of Santa Ana, Orange and Tustin to discuss the agencies existing conveyance and well production facilities, and their desired capacity and conveyance goals. The intent of the meetings was to identify how much groundwater pumping capacity may be available from all of the cities facilities and what modifications could be implemented to increase groundwater pumping so that that excess groundwater could be conveyed in an emergency. For this report, during an emergency when the excess groundwater will be conveyed to South Orange County, no import water was assumed to be available from MWD via the East Orange County Feeder No. 2. Tetra Tech obtained import and well production data as well as copies of the latest Urban Water Management Plan and Water Master Plan for each agency. Three-year historical data (July 2016 through June 2019) of the monthly quantities of ground water pumped and import water were tabulated. Included within Appendix A are Tables A-1 through A-3 which summarize the average historical groundwater and import water supply and demand for each agency per month. It should be noted that the yearly demand within each of the agencies systems will fluctuate based on seasonal demand requirements. In addition, Tetra Tech worked with each of the agencies to summarize the current well operations, the available production wells, the rated maximum capacity of each well, and any proposed well improvements planned in the next few years. A concern noted by all three cities is the Perfluoralkyl Substances (PFAS) contamination of the groundwater basin and how this will dramatically influence future groundwater pumping operations. In discussions with the operators for each agency, it is assumed the pumps will typically be utilized less in the winter months (November through April) to allow for maintenance activities on the wells. Within the Appendix and the appropriate Table "A" for each of the agencies, Tetra Tech has tabulated the following existing well information: well name; estimated average well capacity; theoretical maximum daily production; typical winter daily production; and typical summer daily production. Included within the table, will be any wells that have been identified or expected to have potential issues that will impact production/operation in the future. For this study, Tetra Tech has assumed that OCWD will be responsible for all capital costs and 50% of operation and maintenance cost up to $75/AF for PFAS treatment required at any of the existing or future wells and that this work will be completed in the next two to four years. 2.2 City of Santa Ana The City of Santa Ana Water System has a total of 21 groundwater wells and seven (7) import water connections. Fourteen (14) of the City wells pump into surface reservoirs with booster pump stations pumping the water into the City's distribution system. The remaining seven (7) wells pump directly into the City's distribution system. The City is concerned that potentially nine (9) wells may be impacted in the near term by PFAS and will need PFAS treatment facilities. Five (5) of the import water connections are connected to MET's Orange County Feeder (SA- 1, SA-2, SA-3, SA-4 and SA-5). Two (2) of the import water connections are connected to the East Orange County Feeder No. 2 (SA-6 and SA-7). Table A-1 (within Appendix A), summarizes the eighteen (18) wells that had operated during the three-year historical period. During the three-year historical period, the City has pumped on an average 71% of its water demand from the groundwater basin. Well 29 and Well 32 are currently under design for major rehabilitation. As stated in the City's Water Master Plan and approved CIP, the City is planning to drill and equip a new well at Washington Street and a new well to replace the abandoned Well 22 at the Cambridge Facility. Orange 9t9%9 1District/Moulton Niguel Water District 30 - 15 5/17/2 A TECH Evaluation of Groundwater Conveyance Options 3