Carnation Treatment Plant

The Plant

Carnation Wastwater Treatment System, May 2008 (1.6MB).
Where does it go after you flush, brush or do the dishes? A step-by-step overview of the Carnation Wastewater Treatment System. Backside of handout: Let's Talk Trash - what belongs in the trash can and not the toilet or drain.

The plant treats wastewater to such a degree that highly reclaimed water will be used to enhance a wetland at Chinook Bend Natural Area, a mile and a half north of the Carnation plant.

The Carnation Wastewater Treatment Plant uses an advanced treatment technology called a membrane bioreactor (MBR) system instead of the large round settling tanks used in conventional plants. The membranes are immersed in wastewater. The MBR system sucks wastewater through hollow fibers with microscopic pores small enough to filter out particulate matter and even individual bacteria.

In addition to the reclaimed water, the plant has been designed with numerous “green” features that minimize impacts on the environment, conserve resources and maximize energy efficiency.

The new treatment plant serves about 2,000 people in Carnation’s urban growth area, with capacity to serve up to 4,000 in 2030. At design capacity, the plant is expected to treat 480,000 gallons of wastewater a day.

The water quality of the plant’s effluent – the treated wastewater leaving the plant – is regularly tested. During the start-up phase, treated water from the plant is discharged via the river outfall at Carnation Farm Road Bridge, but flows will eventually be directed to the Chinook Bend wetlands along the Snoqualmie River.

Using the membrane bioreactor technology will also allow for expanded use of reclaimed water that can be used for irrigation and wetland enhancement. King County partnered with Ducks Unlimited to enhance the Chinook Bend wetlands, which provide highly prized habitat for fish and wildlife.