MWD authorizes Local Resources Program agreement for Eastern groundwater desalter

The Metropolitan Water District of Southern California authorized a Local Resources Program agreement with the Eastern Municipal Water District for the Perris II Brackish Groundwater Desalter project.

The Oct. 8 MWD board vote approved the subsidy agreement which is expected to fund $23 million of operations over a 25-year period but could fund as much as $37.5 million if project yield and costs exceed expectations. The agreement covers up to 6,000 acre-feet per year of recovered groundwater.

The desalter will treat groundwater from the West San Jacinto Groundwater Basin which without treatment has high levels of total dissolved solids, nitrate, iron, and manganese. The desalting treatment plant will make that degraded groundwater potable. The Eastern Municipal Water District will own and operate the brackish water desalting plant, and deliveries of potable water treated by the plant are expected to begin in spring 2017.

In 2007 MWD established a goal of developing 174,000 annual acre-feet of new water supply by 2025. The Local Resources Program provides financial assistance to member agencies which meet the policy goals of the program.

Eastern also operates the Perris I and Menifee desalters which combined to treat and deliver 5,859 acre-feet of recovered groundwater during Fiscal Year 2012-13. That 5,859 acre-feet per year will be the baseline for the Perris II desalter, and only project production in addition to that baseline will be eligible for the MWD incentive. The Perris I and Menifee desalters have a combined capacity of 8 million gallons per day of potable water supply; other than ensuring that the Perris II recovered water quantity is in addition to rather than replacing the Perris I and Menifee production the two existing desalters are independent from the Perris II project and not part of the agreement.

The Perris II desalter plant will include an iron-manganese removal facility, two pump stations, a clear well, up to seven new wells, approximately 62,500 linear feet of brackish well water collection pipeline, 11,300 linear feet of brine disposal pipeline, 1,600 linear feet of sewer pipeline, and approximately 2,200 linear feet of potable water pipeline. The plant will use reverse osmosis desalination technology and will have an ultimate potable water capacity of 5.4 million gallons per day.

The agreement between MWD and Eastern includes sliding scale incentives of up to $250 per acre-foot based on actual project unit cost above MWD’s prevailing water rate. The incentives will be calculated annually.

Financial incentives will be paid only for recovered groundwater delivered by the desalter plant for beneficial use, and the conditions of the agreement also include rate structure integrity language, a reduction in MWD’s contract commitment if the project falls short of production targets measured in four-year intervals throughout the agreement term, and termination for non-performance if construction does not commence within two years of the agreement execution or if recovered groundwater deliveries are not realized within five years of the agreement date.

The Oct. 8 MWD action also adopted the California Environmental Quality Act findings, which include a Mitigated Negative Declaration and a Mitigation Monitoring and Reporting Program.

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