West County Wastewater (WCW) Plant Energy Upgrades

Richmond, CA

PACE provided engineering design services as part of the Engie design-build team, upgrading the sludge and solids processing at West County Wastewater District’s (WCW) 12.5-million-gallon-per-day (MGD) Water Quality and Resource Recovery Plant (WQRRP). The upgrades improved the energy efficiency of the plant through the design and installation of new process equipment and a cogeneration system consisting of two gas-fired generators. Additionally, an upgraded motor control center was designed to support process loads and integration of the cogeneration system. PACE designed improved power and control equipment for the new process equipment, including pumps, blowers, mixers, and control panels.

The project replaced two secondary digesters that had reached the end of their useable service life with new ones, which are supported by new foundation drilled displacement columns that provide the requisite support to meet current code. A new solids handling building was designed to provide space for two centrifuges that take digested sludge to 20% solids content and a new dryer system that further dries the sludge to 80% solids content. The solids building also has a gas cleaning room that cleans the gas from the tops of the digesters, which is then used in two cogeneration systems producing 1 megawatt of energy each. PACE also prepared designs for the conversion of three sludge drying lagoons into a new influent equalization basin, which stores high seasonal flows into the plant and prevents disruption to the treatment process.

Key Features:

• 12.5 MGD Water Quality and Resource Recovery Plant (WQRRP)
• New solids handling building space for two centrifuges
• Conversion of sludge drying lagoons into a new influent equalization basin
• Comprehensive short circuit, protective device coordination, and arc flash hazard analysis
• Cogeneration system consisting of two gas-fired generators
• Motor control center upgrades supporting process loads