Regional Wastewater Control Facility Modifications Project

Sewer plant photo

The City of Stockton Regional Wastewater Control Facility (RWCF) sewer treatment plant is undergoing the Modifications Project construction to change the sewer treatment to an activated sludge process and replace equipment and processes that are 40 to 70 years old and beyond their useful life.

The Modifications Project construction map provides an overview of the new, improved and demolished structures.
Modifications Project Information
  • In 2014, the State issued stringent new standards for the discharge of treated wastewater that requires significant changes in the treatment process to meet lower nitrate concentrations by June 1, 2024.
    • The City of Stockton sewer treatment will change to an activated sludge process to meet the State's standards.
    • The Modifications Project also replaces equipment and processes that are 40 to 70 years old and beyond their useful life. 
  • In May 2019, the City Council approved adjustments to the Wastewater Utility rates to be implemented over a five-year period. The rates ensure adequate funding to finance the RWCF Modifications Project.
  • In October 2020, the U.S. Environmental Protection Agency (EPA) awarded the City a $108 million Water Infrastructure Finance and Innovation Act (WIFIA) loan to help finance the Modifications Project.
  • The remaining funds derive from a combination of market-rate municipal bonds and a loan from the California State Water Resources Control Board’s State Revolving Fund.
Current Projects
  • Complete construction of the Modifications Project East Bank Outfall - November 2023
  • Finalize the connection of the new Regional Wastewater Control Facility 3-MegaWatt generator for use during power outage emergencies - October 2023
  • Complete construction of the new Modifications Project Stores building and bulk materials yard area - September 2023
  • Complete construction of Modifications Project Tertiary Processes – Ultra-Violet Disinfection and Disk Filters - August 2023
  • Install final equipment in RWCF Grit Removal Building, including chemical feed lines, electrical controls, and process water connections - May 2023
  • Continue RWCF Modifications Project construction of new Stores Building and Influent Pump Station - April 2023
  • Complete electrical power and wastewater flow shutdowns at the RWCF Modifications Project construction to connect new 3-Megawatt backup generator - March 2023
  • Begin excavation and building of pad footings for new Stores building - February 2023
Completed Projects
  • Scheduled for completion in 2023, the RWCF Modifications Project has completed several steps of the construction in 201920202021, and 2022.
  • Aerial video of the continued construction of electrical, deck work, and concrete reinforcement in Aeration Basin in January 2021
  • Aerial video of the formwork for stem walls on new Administration/Engineering buildings in January 2021
  • Groundbreaking Ceremony - October 8, 2019
  • Aerial view of the Modifications Project between October 2019 and March 2021.
Project Documents
Last Update : 11/06/2023, 13:56:03