Site work and new construction of a water / sewer project in Antioch, California. Completed plans call for site work for a water / sewer project.

Delta Diablo is requesting Statements of Prequalification (SOPQ) from qualified General Contractors interested in bidding on the Secondary Process Improvements Phase 1 Project (Project No. 22126). In accordance with California Public Contract Code Section 20101, only contractors determined by the District to be prequalified will be eligible to submit a bid for the Project. The Project will provide major upgrades to the District’s wastewater treatment facility in Antioch, California, including construction of new aeration basins, a return activated sludge pump station, a secondary clarifier, solids thickening improvements, a new 2.5-megawatt emergency backup generator, and associated electrical, process, and site infrastructure improvements. The estimated construction value is approximately $140 million to $175 million. Construction bids are anticipated to be advertised in June 2026 following completion of the prequalification process.