Environment
ENR 2025 Top 400 Review +: Water Quality Project Reaches Milestone
Part of $341-million California ultraviolet treatment plant will be 65 ft underground
Construction crew maneuvers to build ultraviolet disinfection drinking water treatment plant located 65 ft underground at East Bay Municipal Utility District site in Orinda, Calif.
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Construction on a $341-million water quality improvement project for California’s East Bay Municipal Utility District reached the halfway mark this summer as crews began concrete pours at portions of a large drinking water treatment facility located 65 ft beneath ground level.
The project, expected to complete in 2027, will upgrade the existing Orinda, Calif., treatment plant and replace aging chemical treatment components with ultraviolet disinfection and chlorine.
The utility district identified the need for the project in 2017 when it changed its primary water source from the Mokelumne River to the Sacramento River and realized the need for improved water quality in light of climate change fluctuations.
Flatiron Dragados is prime contractor on the project, which will introduce ultraviolet disinfection and a chlorine contact basin to improve treatment processes and reduce formation of disinfection byproducts. Members of the design team include Carollo Engineers, Stantec and Arcadis.
90%
Amount of water to be filtered and treated at site coming from snowmelt.
Source: East Bay Municipal Utility District
The project requires a two-level excavation—supporting a tunnel-boring operation above and concrete slab construction below—that has demanded staged bracing and innovative sequencing to maintain stability and progress.
Crews currently are focused on the two-level excavation for both the ultraviolet disinfection and chlorine contact basin structures, with the slab that forms the roof of the UV chamber serving as the base of a two-story maintenance and electrical building.
Manager Jared Herrington says that the team has carefully sequenced work on the project to keep construction on track.
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