West County Wastewater (WCW) Plant Energy Upgrades

Richmond, CA


PACE is providing engineering design services as part of the Engie design-build team that is upgrading the sludge and solids processing at WCW’s 12.5-million-gallon-per-day (MGD) Water Quality and Resource Recovery Plant (WQRRP). The upgrades will improve the energy efficiency of the plant through the design and installation of new process equipment, including pumps and aeration blowers, and the addition of Variable Frequency Drives (VFDs) that allow greater process control.


The project will replace the two existing secondary digesters, as they have reached their end of useable service life. The new digesters will be supported by new foundation drilled displacement columns that will provide the requisite support for the new digester tanks to meet current code. A new solids handling building was designed to provide space for two centrifuges that will take digested sludge to 20% solids content and a new dryer system that will further dry the sludge to 80% solids content. The solids building will also have a gas cleaning room that cleans the gas from the tops of the digesters, which will then be used in two cogeneration systems that each produce 1 megawatt of energy.


PACE is also preparing a design to convert three of the WQRRP’s sludge drying lagoons into a new influent equalization basin to store high seasonal flows into the plant and prevent disruption to the treatment process.


Key Features:

  • 12.5 MGD WQRRP
  • Sludge and solids processing upgrades
  • Replacement of aging digesters with new digesters and deep foundations
  • New solids handling building for sludge dewatering and drying
  • Converted three sludge drying lagoons into a new influent equalization basin

ENGIE Services U.S.

Wastewater Treatment