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EPA, Northwest Natural Agree on Tar Clean-up in Portland Harbor

Release Date: 4/29/2004
Contact Information: Judy Smith
(503) 326-6994

April 29, 2004

Tar-laden sediment will be removed from the Willamette River site this summer.

The U.S. Environmental Protection Agency and Northwest Natural have formalized an agreement to remove contaminated tar-laden sediment along the former Portland Gas and Coke Company (GASCO) site in Portland Harbor this summer. Northwest Natural currently owns and operates the site.

The GASCO project is the second “early action” agreement for the Portland Harbor Superfund Site. EPA, and the first in-water removal of contamination since Portland Harbor was added to the National Priorities List in 2000. EPA has worked collaboratively with DEQ, six northwest tribes, and other state and federal agencies to identify potential early actions.
photo of shoreline with tar contamination
Tar on the shores of the Willamette River.
(Click photo for larger image)

Sediment along the riverbank and river bottom next to the GASCO site is contaminated with tars containing polynuclear aromatic hydrocarbons and benzene. EPA has determined that removing the tar-body is time-critical and needs to take place quickly to reduce the possibility of releases of hazardous substances from the tar-body into the Willamette River and downstream areas. (See photo)

The Administrative Order on Consent (AOC) that the EPA and Northwest Natural voluntarily signed this week commits Northwest Natural to develop a work plan within 30 days, with the goal of completing removal of the tar-body in the river this summer, at times when the least impact to migrating salmon would occur. (The order is available by request or at .

GASCO, built and operated an oil gasification plant on the site between 1913 and 1956. From 1913 to 1941, waste and by-products from various gas production operations were discharged to a stream channel to the Willamette or low-lying areas of the site. From 1941 to 1956, wastewater effluent and tar still bottoms or residuals were disposed of in settling ponds. Approximately 30,000 cubic yards of tar waste had accumulated by the time the plant was shut down and the ponds were buried under 10 feet of fill in 1973.

“Northwest Natural is doing the right thing by agreeing to remove a known source of contamination in the river,” said EPA Regional Administrator John Iani. “In addition, the GASCO tar-body removal is responsive to public desires to get an early start on cleanup where it is possible.”