March 11, 2004

Treatment plant a showcase for green design

Rendering by CH2M Hill Seattle’s $78 million treatment plant will include a green roof, certified wood, and passive lighting and ventilation.

The city of Seattle's second major new water treatment facility is scheduled for completion in June.

The $78 million Cedar River Water Treatment Facility, situated on 17 acres at Lake Youngs outside Renton, will use recycled construction materials, passive ventilation and lighting and certified sustainable wood.

The operations building will also sport a green roof. The project team hopes to obtain a gold LEED certification for the building.

Design components of the operations building, the only non-process building on the site, include waterless urinals, recycled materials and an environmental-controls system that is designed to minimize power use while maximizing building comfort.

An indoor air quality plan and commissioning plans have been developed to optimize the building's environmental conditions. Recycled materials used in the building include rebar, metal studs, gypsum wall board, metal roofing, carpeting and Ecosurface soft-floor covering.

Due to the sensitive nature of the site, which includes an 11 billion-gallon lake that acts as a storage reservoir for finished drinking water, extra precautions were taken throughout construction. These included a review of all chemicals used around the lake, and the provision of spill kits to clean accidental spills. All employees were briefed about preserving water quality before being allowed to work on-site.

Water quality monitoring stations were placed in the lake, and daily samples were taken to ensure construction activities did not affect the water quality. Also, the contractor worked to prevent non-native plant species from contaminating the lake.

The project team undertook several strategies to minimize disturbances to the site. The design focused on a campus plan, which broke the site into a number of smaller footprint buildings. Instead of a couple of large buildings, the Cedar site includes nine smaller structures.

The project also reused over 13,000 lineal feet of 78-inch-wide steel pipe in lieu of installing new pipe. The existing pipe was inspected and repaired as needed.

Wetlands were protected throughout construction and checked by an environmental monitor who also performed daily site inspections.

Through December, 86 percent of the project's construction waste — 662.5 tons — had been diverted from landfills.

The facility is being built under a design-build-operate contract by CH2M Hill in partnership with contractor M.A. Mortenson Co.

Operations Management International Inc., a CH2M Hill subsidiary, will operate the facility.

Seattle Public Utilities, the city's water provider, estimates design-build-operate procurement will save $50 million compared to a traditional design-bid-build process. The city retains actual ownership of the facility.

The Cedar facility supplies 70 percent of SPU's water. When the facility is complete, it will be capable of treating 180 million gallons per day, while meeting or exceeding federal water quality standards.

The Cedar plant will use ozonation to disinfect water. Additionally, the Cedar facility will use ultraviolet light, a process recently determined to be very effective for disinfection. When complete the plant will be the largest ultraviolet drinking water treatment plant in the world.

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