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FINAL DRAFT PRELIMINARY REPORT <br />(Connections to EOCF #2) <br />A contingency of 30% has been included in the construction cost to provide for uncertainties and unknowns <br />associated with a preliminary design. The overall project cost includes a 10% design cost, 15% construction <br />contingency, and 15% technical, legal and administrative costs. <br />The estimate of construction costs are based on 2020 dollars, ENR Construction Cost Index of 11436 for June 2020. <br />The following Table 7.1 summarizes the proposed excess groundwater potential, the probable construction costs, <br />and the overall total project cost. <br />Table 7.1 Summary of Excess Groundwater Potential and Project Costs <br />Proposed Facility <br />Potential Excess <br />Groundwater <br />Probable <br />Construction Cost <br />Total Project Cost <br />City of Santa Ana — East Station Facility <br />14 cfs <br />$ 16,000,000 <br />$ 22,400,000 <br />City of Santa Ana — Cambridge Facility <br />10 cfs <br />$ 15,000,000 <br />$ 21,000,000 <br />City of Orange — City Yard Facility <br />12 cfs <br />$ 17,000,000 <br />$ 23,800,000 <br />City of Orange — Batavia Plant <br />7 cfs <br />$ 17,000,000 <br />$ 23,800,000 <br />City of Tustin — Walnut Well Site <br />3 to 5 cfs <br />$ 14,000,000 <br />$ 19,600,000 <br />8. SIMILAR STUDIES <br />8.1 MWDOC Planning Level Reliability Alternatives Analysis <br />Municipal Water District of Orange County (MWDOC) had an evaluation performed to update the available <br />emergency water supply from Irvine Ranch Water District (IRWD) that could be made available to South Orange <br />County (SOC) Agencies during an emergency shutdown or outage of MWD treated imported water supply from <br />Diemer Filtration Plant. The study was titled: "Planning Level Reliability Alternatives Analysis", dated April 9, <br />2019, and was prepared by Dudek. The study evaluated IRWD's ability to convey groundwater supply through <br />their system to the Joint Transmission Main (JTM) for conveyance to SOC. In addition, a scenario to convey <br />groundwater via the East Orange County Feeder #2 (EOCF#2) to the JTM was also discussed. <br />Determination of available emergency potable water supply was based on a two-part analysis of: <br />• Part 1: IRWD's water balance of water supply versus their demands, assuming no MWD treated <br />imported water supply from the Diemer Filtration Plant is available. <br />• Part 2: IRWD system's hydraulic capacity to convey available water supply across their system to an <br />interconnection with the JTM. <br />The ability to convey groundwater supply through IRWD system is contingent on the hydraulic capacity of their <br />system complicated by varying demand conditions. The amount of emergency supply capable of being <br />conveyed to SOC by IRWD will vary and not necessarily be a single fixed "reliable" supply amount provided <br />during emergencies that could occur at any time during the year. <br />If the groundwater is conveyed using the EOCF#2, the available supply flow is much more predictable since <br />fluctuations of the retail water system does not significantly impact the ability to convey water due to the size of <br />the EOCF#2. <br />Based on the results of the analysis, five (5) scenarios were identified, along with the available 60 day supply, <br />the planning level estimate of construction cost and target year of operation. The following is a brief summary <br />of the results: <br />Orange 9tq%9 1District/Moulton Niguel Water District 30 — 29 5/17/2k2fkA TECH <br />Evaluation of Groundwater Conveyance Options 17 <br />