FPUD, Rainbow approve MOU for regional water activities

Joe Naiman

Village News Reporter

Both the Fallbrook Public Utility District and the Rainbow Municipal Water District have approved an initial Memorandum of Understanding (MOU) to improve regional water supply reliability.

A 5-0 FPUD board vote Jan. 23 approved the preliminary MOU and a 5-0 vote at the Jan. 24 Rainbow board meeting approved that MOU. The parties also include the Rancho California Water District (RCWD), Marine Corps Base Camp Pendleton, and the City of Oceanside.

“We are working together so we can identify any potential future local projects that could strengthen our water supply reliability in a cost-effective way,” said FPUD General Manager Jack Bebee. “For FPUD in particular, we are looking to expand our recycled water usage and facilities.”

The MOU covers six planned projects: an Upper Santa Margarita River advanced purification facility, an Upper Santa Margarita River brine line, expansion of FPUD’s recycled delivery system, a Lower Santa Margarita River advanced purification facility, Oceanside Pure Water expansion and outfall improvements, and Bonsall Basin groundwater recovery along with a brine line.

“This will be a multi-watershed area,” said Rainbow General Manager Tom Kennedy.

The five agencies have been working together to identify potential future projects to improve regional water supply reliability. These agencies desire to implement a regional facility approach to water management and brine waste discharge which would efficiently expand utilization of local water supplies. This is regarding groundwater, surface water, and recycled water. The agencies also desire to increase water supply reliability in a cost-effective manner.

The MOU does not commit any agency to construct any facility; rather it states that the agencies will work cooperatively on studies and pursuit of funding opportunities and will also maximize the use of existing infrastructure to minimize the overall cost of the projects.

A master list of plans will be provided by MOU for future development of cost-effective water supplies in the Santa Margarita and Lower San Luis Rey watersheds. New potable reuse regulations are expected in 2023 which should reduce some obstacles for agencies without appropriate groundwater or surface water facilities, and the MOU could also increase the pace of development of the planned potable reuse projects.

The City of Oceanside has an existing Oceanside Ocean Outfall Pipeline with a permitted discharge capacity of 41.5 million gallons per day (mgd). Oceanside discharges both recycled water and brine waste to the outfall pipeline. Those flow through the San Luis Rey Land Outfall and brine pipelines which have a permitted multi-agency discharge limit of 13.5 mgd.

Oceanside would like to implement various projects to utilize its water, recycled water, and wastewater facilities more efficiently and to work with other agencies to ensure there is sufficient capacity in its outfall lines to support regional water supply development. Also, they are interested in increasing the capacity of their potable reuse program. They recently completed an indirect potable reuse project.

FPUD has an existing land outfall pipeline from FPUD to Oceanside and a 2.4 mgd capacity allocation in the Oceanside Outfall. FPUD currently discharges excess recycled water and brine to the Fallbrook outfall pipeline and ultimately to the Oceanside pipeline. They would like to expand use of recycled water in the FPUD service area and reduce the recycled water disposal through the pipelines.

Camp Pendleton also has an existing land outfall pipeline from the Marine Corps base to Oceanside and discharges both excess recycled water and brine waste to those pipelines. They desire to develop a potable reuse project in the Lower Santa Margarita Basin and reduce the base’s discharges to the Oceanside Outfall.

Rainbow desires to develop its groundwater resources in the San Luis Rey Basin. They own a capacity right of 1.5 mgd in the Oceanside Outfall, and their groundwater development program may require disposal of brine through the outfall pipeline.

A feasibility study is currently being finalized for Rainbow’s San Luis Rey Imported Water Return Flow Recovery Project. That study should be completed in mid-2023. Rainbow is also evaluating the reclamation of about 1 mgd of wastewater which is now treated for ocean disposal.

Each of Rainbow’s new supply sources would generate salty brine solutions as a by-product of the treatment processes used to create potable water. The disposal of brine solutions is a significant challenge for the economic viability of those projects.

Rancho Water hopes to implement an indirect potable reuse project to maximize the use of recycled water and improve the water quality of supply from the Santa Margarita River Watershed. It would reduce the amount of recycled water disposed outside of the Santa Margarita Watershed, increase water supply reliability, and reduce salinity.

The RCWD project requires the disposal of brine from the demineralization of recycled water. The district desires to dispose of that brine to the Pacific Ocean by utilizing available capacity within the Oceanside and Fallbrook outfall lines.

If all of the projects are implemented and all achieve the anticipated production. They are expected to create 17,850 acre-feet of new supply each year. The City of Oceanside would add 9,250 acre-feet annually consisting of 5,190 acre-feet from recycled water expansion and 4,060 acre-feet from potable reuse.

The RCWD advanced purification facility and brine line project would increase annual supply by 5,000 acre-feet. Rainbow’s Bonsall groundwater treatment plant and brine line would create an additional 2,000 acre-feet each year. The Camp Pendleton advanced purification facility would add 1,100 annual acre-feet. FPUD’s recycled water system expansion would provide 500 more acre-feet annually.

The five agencies will work together to develop a feasibility study for the components of the projects. Each agency will be responsible for developing the necessary studies for their facilities, will coordinate and provide input, and they will cooperate to identify funding opportunities for the projects. No agency is obligated to share any funding received, but they will work together and jointly pursue funding when appropriate.

FPUD and Rancho will finalize the agreement necessary to utilize the Fallbrook land outfall pipeline for brine waste disposal. Oceanside and Rancho will finalize the agreement necessary to utilize the Oceanside pipelines for brine waste disposal for flows exceeding FPUD’s existing outfall capacity.

Oceanside and Camp Pendleton will develop a long-term discharge agreement. The agencies will also coordinate any activities associated with changes to the waste discharge permits issued by the Regional Water Quality Control Board.