Desert Water Agency advances $6m effluent reservoir rehabilitation project

Desert Water Agency advances $6m effluent reservoir rehabilitation projectThe California utility will open bids in October to replace the deteriorated roof and recoat the interior and exterior of its post-treatment effluent reservoir to safeguard water disinfection.

The board unanimously authorized a call for bids for the Effluent Reservoir No. 1 Rehabilitation and Recoating Project, which has a total budget of $6 million and an estimated construction cost of $3.6 million.

The project involves the complete replacement of the reservoir's corroded roof structure, utilizing a design that minimizes inaccessible areas and employs special coatings to prevent future corrosion.

Maintaining a closed roof on the post-treatment reservoir is required to prevent sunlight exposure, which could spur algae growth and compromise the water's chlorine disinfection.

Bids are scheduled to open on October 6, 2026, with construction anticipated to begin before the end of the year and conclude by late spring 2027.

Desert Water Agency's Board of Directors unanimously approved a call for bids for the Effluent Reservoir No. 1 Rehabilitation and Recoating Project during its September 1, 2026 meeting. The infrastructure upgrade carries a project budget of $6 million, with engineering, construction, inspection, and agency labor costs estimated at approximately $3.6 million. The project will address severe corrosion on the reservoir's existing roof. The scope of work includes the complete replacement of the roof structure alongside the recoating of both the interior and exterior of the tank. According to a staff presentation by Mr. Mulholland, a tank design consultant evaluated multiple alternatives and determined that a new roof, designed to minimize inaccessible areas and utilizing special coatings, was the most cost-effective option over the asset's lifespan. During the meeting, Vice President McKenna inquired why the agency could not simply leave the reservoir open to the elements, as it had done with a previous influent reservoir project over a decade ago. Mulholland clarified that because Effluent Reservoir No. 1 holds post-treatment water, it must remain covered. Exposing the treated water to sunlight would promote algae growth, which would consume the chlorine used for disinfection and risk regulatory non-compliance before the water leaves the facility. With the board's authorization, the agency expects to open bids on October 6, 2026. Staff will then review the submissions for compliance and return to the board for the final contract award. Construction is slated to begin before the end of the year, with completion targeted for late spring 2027.