The Metropolitan Water District of Southern California (MWD), which provides safe and reliable drinking water to nearly 18 million people, is adding ozone disinfection facilities to its Robert A. Skinner Water Treatment Plant, a 630-million-gallon-per-day (mgd) potable water treatment plant that operates 24/7. The Skinner plant, named for a Metropolitan general manager (1962–1967), consists of 7 treatment modules, with a total of 11 flocculation basins, 8 settling basins, 124 filters, and a 110-million-gallon finished water reservoir. The plant is located in Winchester, CA, and is one of MWD’s 5 filtration plants. It supplies treated water to 2.5 million customers of three MWD member agencies—the Eastern and Western Municipal Water Districts in Riverside County and the San Diego County Water Authority—and is the prime source of drinking water for the San Diego region.

Influent-metering vault for 144-inch plant influent conduit	Rebar layout for ozone contactor

After conducting an exhaustive competitive selection process that spanned more than 1 year, MWD selected Parsons for construction management of its $190 million Oxidation Retrofit Program (ORP). We were chosen because of our overwhelming management and technical experience. The retrofit program includes the following new major facilities:

Staged 144-inch and 60-inch Skinner ORP piping

• Six ozone contactors and one ozone generation building that houses five 4,000-lb/day ozone generators

• Three 37,000-gallon liquid oxygen (LOX) storage tanks and feed equipment

• 630-mgd plant influent structure

• Three chemical storage and feed systems (sulfuric acid, hydrogen peroxide, and caustic soda) to control pH, taste, and odor

• New power substation and electrical switchgear building

• 60-mgd coal removal system

• 34-mgd washwater clarification system

• 60-mgd washwater return pump station

• Interconnecting pipelines with diameters ranging from 5 to 12 feet

The new facilities will use delivered LOX for ozone production while providing space for a future cryogenic oxygen production facility. This project presents three critical challenges:

• Construction in and around facilities that are operating

• Integration of complex controls into an existing plant supervisory control and data acquisition system

• Coordination among three contractors who are completing projects to expand and upgrade the plant

Overflow spillway for ozone contactor	Overview of 34-mgd Washwater Reclamation Plant 3 (WWRP3)

The new facilities and existing structures can only be tied in during carefully planned plant shutdowns and only during specific time periods.

Parsons is meeting specific milestones to prevent any delays affecting this project as well as both the coordinated efforts of the Skinner plant maintenance schedule and the efforts of other member agencies. Thus, schedule management is the key to this project’s success—and cooperation is critical among the multiple construction managers, contractors, MWD member agencies, and operations staff. Plant operations continue to report that Parsons’ requirements for early milestone startup activities and shutdown work efforts have resulted in very effective project management.

Parsons is supporting the goals of MWD’s small business outreach program by engaging eight subcontractors who represent more than 30% of the dollar value of the construction management effort. Our subcontractors are fully integrated into the Parsons team and are providing inspection, materials testing, surveying, geotechnical engineering, fabrication inspection, document control, and administrative support services.

When completed, the Skinner Water Treatment Plant will be one of the largest ozone facilities in the United States. It will improve water quality by lowering disinfection byproducts to meet new federal and state laws, reducing taste and odor, and by allowing an unrestricted blending of MWD’s two water sources—California State Water Project and the Colorado River. The project is scheduled for construction completion in May 2009 and the MWD initial and performance testing periods in November 2009.

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