Tumwater approves agreement to maintain Palermo Treatment Lagoon


The Tumwater City Council approved an interlocal agreement between Tumwater and the Washington Department of Transportation (WDOT) to maintain the Palermo Treatment Lagoon Thursday, May 19.

According to City Administrator John Doan during the city’s Public Works Committee meeting, the $100,000 agreement will include providing routine maintenance for the aeration facility and address some of the neighborhood landscape issues in the area.

Officially the “Palermo Wellfield Superfund Site,” the project was begun in 1993 when Tumwater discovered two contaminants in the city’s drinking water wells, according to a report from the U.S. Environmental Protection Agency (EPA). The contaminants came from Washington Department of Transportation facilities and a local dry cleaning firm. While the wells were taken out of service immediately, EPA began cleanup of the affected ground starting in 1998.

The City Administrator also assured the council that they will work with the community development department to ensure that all of our permitting needs are met.

"The contaminant levels continue to decline. However, they are still present, which is why we need to continue to collaborate with them [WDOT] to ensure that our drinking water continues to be safe," Doan said.

According to Doan, some additional work is going on down on Palermo Avenue. They are currently working on a treatability pilot. So the workers are installing several wells.

“These facilities would serve as a ’wall’ and prevent water contamination,” Doan explained. “Currently, they're piloting and seeing if it is effective for the cleanup within the neighborhood, and it's safe for groundwater.”

Doan assured there are no implications from a public safety or health standpoint.

Groundwater Treatment in Palermo Wellfield Area

Doan said that there is a lot of natural-flowing water that pumps out in the Palermo Wellfield area. The natural flow of water is from the west to the east down to the Deschutes Valley - the Deschutes River. 

“So as the groundwater flows this way, so do emanations and moves with it,” furthered Doan. “Hence, the wellfield has historically captured this plume in the mid-2000s or early or late 1990s.”

Doan said the system EPA installed  is still working and that the aeration system effectively captures and treats the plume. 

"So any water that we actually deliver to our customers is free of any contaminants. Both of these contaminants are what they call Baltimore organic compounds," the city administrator mentioned.

However, Doan said Palermo's aeration facilities and treatment system remained in place because of the positive benefits they provided to the region.


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  • More info on the treatment/remediation of the groundwater contaminants trichloroethylene and perchloroethylene at the Palermo aeration basin is at the website


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