March 24, 2016

$239M Chambers Creek treatment plant expansion on track to be done this year

Photo from Mortenson Construction [enlarge]

Mortenson Construction expects to finish a multi-year expansion of Chambers Creek Regional Wastewater Treatment Plant in University Place by December.

Mortenson, the general contractor/construction manager, has been working on a $239 million contract since February 2012 and recently logged 1 million worker hours without a lost-time injury. Mortenson has improved or built 32 facilities — including administrative buildings — on the expanded campus.

Work is in the final phase, so the new plant and added capacity will be brought on line.

This last phase also includes transferring 5 million gallons of “mixed liquor” from the old plant to the new one. After that, the plant's new secondary clarifiers will be tied into the new system, and two new anaerobic digesters will be turned on.

The new digesters will join three existing ones to create gas to run boilers, rather than using natural gas or another external power source.

The five digesters are expected to substantially curb demand for external power at Chambers Creek. Mortenson says wastewater treatment plants account for up to 40 percent of a typical utility's electrical costs.

About 252,000 Chambers Creek customers generate an average of 19 million gallons of wastewater daily, and that number is expected to hit 28 million gallons by 2020. The expansion will increase capacity to 43 million gallons daily, allowing the plant to handle projected demand through 2040.

Chambers Creek would have reached maximum capacity this year without the expansion, according to Pierce County, which operates the plant.

Before being discharged into Puget Sound, treated water at the Chambers Creek plant is disinfected by ultraviolet radiation, breaking up DNA chains in bacteria to prevent reproduction. Reclaimed water is also used on the nearby Chambers Bay golf course.

Brown and Caldwell is the designer engineer for the expansion. Kennedy/Jenks Consultants designed the yard piping, site drainage, solids handling building and reclaimed water facility.