MWD approves contracts to update Skinner treatment plant ozone system


The Metropolitan Water District of Southern California approved two agreements for the upgrade of the ozone control system at the Robert A. Skinner Water Treatment Plant.

The Nov. 5 MWD board vote awarded a $476,000 procurement contract to Royal Industrial Solutions for the upgrade of the system and authorized an agreement with Suez Treatment Solutions for up to $320,000 to provide specialized technical support during the upgrade. The replacement of existing structures was also found to be categorically exempt from California Environmental Quality Act review.

The Robert A. Skinner Water Treatment Plant treats both Colorado River Aqueduct and State Water Project supply and delivers that treated water to the Eastern Municipal Water District, the Western Municipal Water District and the San Diego County Water Authority. When the plant began service in 1976 its treatment capacity was 150 million gallons per day, and subsequent expansion of the plant now allows for a capacity of 350 mgd.

Ozone is the primary disinfectant used at each of MWD’s treatment plants. The control of toxic algae and compounds which cause undesirable taste and odor allows MWD to treat any blend of Colorado River Aqueduct and State Water Project supply. The ozone treatment process equipment includes liquid oxygen storage tanks, ozone generators, high-voltage power supply units, a cooling system, ozone contractors, destruct systems and safety and water quality monitoring equipment. The systems are controlled by a series of networked programmable logic controllers which interact with the plant’s supervisory control and data acquisition system.

MWD’s first three ozone systems were at the Skinner treatment plant, the Henry J. Mills Treatment Plant in Riverside and the Joseph Jensen Treatment Plant in Granada Hills. Those systems originally used a type of programmable logic controller which was introduced to the commercial market in 1988. The manufacturer no longer produces or supports that equipment, and the hardware MWD has from that era is now outdated. MWD replaced the ozone control system at the Jensen plant in 2018, and the Mills plant system will be replaced in the future.

The upgrades include the procurement and installation of new control equipment including programmable logic controllers and new programming for the ozonation system. Twelve new programmable logic controllers along with associated electronic components and related communication hardware will be provided by Royal Industrial Solutions. Suez Treatment Solutions will install updated ozone control software into the new programmable logic controllers and will also assist MWD staff with the startup and testing of the updated ozone control system. MWD staff will perform the final design, relocate electrical wiring outside the programmable logic controller cabinets, conduct system integration tests and certify the functionality of the control system.

In addition to the $476,000 procurement contract and the $320,000 technical support agreement, the $1,455,000 budget includes $126,000 for final design work, $145,000 of MWD staff time to perform the work, $77,000 for communications equipment, $115,000 for contract administration, environmental support and project management and $196,000 for contingency.

MWD expects the ozone control system upgrades to be complete by March 2020.

Joe Naiman can be reached by email at