West County Wastewater nears digester commissioning, cites $10.5m in consultant-driven savings

West County Wastewater nears digester commissioning, cites $10.5m in consultant-driven savingsAs the California utility prepares to seed its second anaerobic digester and bring new centrifuges online, officials credit engineering firm HDR with refuting $8 million in contractor change orders and saving $2.5 million in project management costs.

Seeding of Digester 101 began on March 31, with Digester 102 scheduled to follow on May 11.

The district expects to achieve Class B biosolids production and take over sludge transport from contractor Opterra by mid-June.

Shifting primary project management duties from Carollo to HDR saved the district $2.5 million.

HDR's contract tracking enabled the district to reject approximately $8 million in change orders requested by Opterra.

West County Wastewater District (WCW) in California is advancing the commissioning phase of its Clean and Green capital upgrade, with power generation and in-house biosolids processing expected online in the coming months. During a May 5, 2026, meeting of the Infrastructure, Operations & Environment Committee, Senior Project Manager Keith Reynolds reported that the seeding of Digester 101, which began on March 31 using seed sludge from the City of Richmond, has been highly successful. The unit's temperature has been maintained between 95 and 98 degrees, and pH levels have held steady at 6.83. Following this stability, the district plans to begin seeding Digester 102 on May 11. Once both digesters are stable, WCW will commission its new centrifuges, targeted for late May or early June. This will allow the facility to produce Class B biosolids. By mid-June, the district expects to assume responsibility for transporting the sludge offsite—a cost currently borne by the project contractor, Opterra. Simultaneously, construction at the headworks is progressing. Opterra is building a permanent U-shaped bypass system that will allow WCW staff to route flows directly to the wet well during future maintenance. Reynolds noted this permanent infrastructure will eliminate the need for confined space entry and temporary bypass pumping during future grid system maintenance. Beyond physical construction milestones, district officials highlighted significant financial victories driven by their project management strategy. Reynolds noted that shifting primary project management support from Carollo to HDR saved the district $2.5 million. Furthermore, HDR's strict contract tracking and attention to detail provided the documentation necessary for WCW to refute approximately $8 million in requested change orders from Opterra. General Manager Andrew Clough noted that the initial overlap of consultants was an intentional strategy for a project of this scale. The approach allowed WCW to shift responsibilities to HDR as the project evolved, extending the consultant's budget while utilizing HDR's technical expertise to train plant staff on the new anaerobic digestion and gas systems.