Tesoro Water Facilities

Orange County, California

Michael Baker provided design and construction phase engineering support services for 15,500 linear feet (LF) of 24-inch potable water and 20-inch recycled water transmission pipelines (cement mortar lined and coated welded steel), one 3.0-MG potable Zone II water welded-steel tank, and one 2.0-MG recycled Zone B water welded-steel tank. The project included 163,000 cubic yards (CY) of earthwork, plus 102,000 CY of remedial grading for construction of a 7,500 LF all-weather access road and tank pad. The pipeline and roadway construction also required the relocation of 700 LF of an existing 18-inch sanitary sewer pipeline, which serves the entire Coto de Caza community of approximately 15,000 residents.

We led the design team, providing the Santa Margarita Water District with professional engineering and surveying services, including hydraulic studies, preliminary and final design and construction engineering support services.

Additional operational and emergency water supply was required to meet the needs of existing and proposed development in the Escencia Village in Rancho Mission Viejo, which also utilizes recycled water to meet irrigation and other non-potable water demands. The project’s accelerated schedule included three separate construction packages to ensure that the potable water and recycled water facilities would be constructed and operational prior to the summer of 2017. Also, significant coordination and construction monitoring were required to minimize environmental impacts and provide native habitat restoration.

The project faced several challenges, including the need to maintain continuous flow in the sewer system during the relocation of 700 LF of 18-inch sanitary sewer. In response to this challenge, we developed a detailed bypass plan which included a spill prevention plan and emergency spill response plan. Because the area lacked public utility facilities, four photovoltaic (solar) systems were designed to provide power for cathodic protection rectifiers and reservoir telemetry equipment. Lastly, design and construction required coordination with the construction of Los Patrones Parkway, which includes a 50-foot high fill over the pipeline alignment.


“The new Tesoro infrastructure facilities will help the Santa Margarita Water District maximize their available water supply resources to best serve their customers in south Orange County.”

John N.
Project Manager

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