FPUD approves solar mixer for Red Mountain Reservoir

Joe Naiman

Village News Reporter

The Fallbrook Public Utility District will be adding a second floating solar mixer to Red Mountain Reservoir.

FPUD's board voted 5-0 Aug. 23 to approve the purchase and installation of a SolarBee mixing unit from IXOM Watercare, Inc., which will be paid $71,323. The mixer system will be a second mixer and will not replace the SolarBee mixer installed two years ago.

"This will be beneficial because it will essentially stir or mix the water in our reservoir, keeping it from stagnating and maintaining good water quality," said FPUD general manager Jack Bebee.

Without a mixer system, suspended solids settle out in Red Mountain Reservoir over time, which creates sediment on the floor of the reservoir. The sediment must be removed periodically to maintain water quality, which requires the draining of Red Mountain Reservoir. The bottom 24 feet, which equates to 65 million gallons, are at an elevation which does not provide adequate pressure to the system, so the water would need to be discharged into the nearby creek.

A solar mixer system minimizes the settling out process and reduces the need to drain the reservoir for cleaning. The buildup of sediment also degrades the water quality and the reactors' power in the reservoir's ultraviolet treatment system would need to be increased to meet water quality standards, so a mixer's water quality improvement results also reduce FPUD's electricity costs.

In June 2018, the FPUD board awarded a contract for a SolarBee mixing unit capable of mixing 5,000 gallons per minute. The mixer was installed in early 2019, and the reservoir has not experienced a stratification event since the installation.

FPUD and Camp Pendleton are partnering on the Santa Margarita River Conjunctive Use Project which will enhance groundwater recharge and recovery capability within the lower Santa Margarita River basin and increase available water supplies for FPUD and Camp Pendleton.

Much of the Conjunctive Use Project water will be conveyed to the Gheen Reservoir and the Martin Reservoir, but the amount of water FPUD will obtain depends on weather conditions and, if there is additional surplus water, that supply will be conveyed to the Red Mountain Reservoir. The Conjunctive Use Project is expected to be completed in early 2022. The increased volume led FPUD staff to recommend a second mixer.