Michelson Water Reclamation Plant Phase II Improvements
To keep up with growing demand for potable water and a decreasing imported water supply, Southern California’s Irvine Ranch Water District (IRWD) adopted progressive water reuse and conservation standards and began ambitious capital improvement projects. The Michelson Water Reclamation Plant (MWRP) Phase 2 Expansion Project increased capacity of MWRP from approximately 18 million gallons per day (MGD) to 28 MGD. IRWD hired Tetra Tech to serve as a key partner in the design and construction engineering services for the project.
About 20 percent of IRWD’s current supply is recycled water, enough to provide landscape irrigation for 80 percent of the District’s business and community customers—including parks, school grounds, and golf courses—keeping IRWD’s water rates among the lowest in Orange County. The MWRP Phase 2 Expansion allowed IRWD to continue providing water to meet the community’s needs while decreasing IRWD’s dependence on imported potable water.
Tetra Tech was a key partner in the design and construction engineering services for the project. Improvements to the plant during Phase II included upgrades and additions to all portions of the plant. Upgrades included improvements to influent sewers, installation of a new headworks facility, addition of new sedimentation tanks, expansion of flow equalization tanks, a new aeration blower, construction of a membrane bioreactor, high-rate clarifiers, chlorine contact chamber improvements, ultraviolet disinfection facility, new water pumps, and an electrical system expansion.
The team worked to replace the influent sewers that feed the plant from the north and south and joined them at a new junction structure that connected to the newly constructed headworks facility. The team designed this new facility to include three automatically cleaned screens and three vortex grit chambers. The headworks was constructed to handle average flow of 33 MGD and peak flow of 63 MGD.
In addition, four new primary sedimentation tanks were added to supplement the five existing tanks for a total capacity of 33 MGD, and the existing flow equalization tanks were expanded. A new primary effluent pump station was constructed to direct flow to the existing secondary treatment process and the newly constructed bioreactor. A new aeration blower also was added to the existing secondary treatment system to provide backup for the treatment process.