The Washington Department of Ecology announced Thursday it had reached an agreed order for the Port of Seattle to evaluate and plan for a final cleanup of sediment contamination at its Terminal 90-91 complex in Smith Cove.

Sediment contamination at the complex has been found to include metals, polychlorinated biphenyls (PCBs), semi-volatile organic compounds and petroleum-based hydrocarbons, which are the result of an extensive history of military and industrial uses at the site.

Various oil companies operated a tank farm at the site between 1926 and December 1941, at which point the Navy took possession of the Terminal 91 facility through condemnation to use it as a receiving and supply depot.

The Port of Seattle acquired the Terminal 91 facility after the Navy declared it surplus in 1976.

Port of Seattle project manager Kathy Bahnick said the port actually developed the two piers and uplands in the 1910s; before the Navy took over the sites, consolidated them and filled in the north end with dredge material.

“The piers themselves really haven’t changed,” she said. “They’re earthen-filled, so the centers of them are dirt.”

When the port took over ownership in 1976, most of the operations were petroleum-related.

“And at that time people weren’t thinking petroleum was much of anything,” Bahnick said.

The port owned the tank farm lease parcel, and various parties, including Burlington Environmental Inc., operated a dangerous waste management facility there starting in November 1980 and ending in September 1995. Those operations included as a waste oil reclamation facility.

Ecology approved the above-ground tank closure work in 2003, and the facility was demolished in 2005.

The U.S. Army Corps of Engineers conducted a partial sediment cleanup in 2012, which included the removal of munitions dating back to World War II, which the Navy had dumped overboard without documentation and were later discovered near the complex.

The port cleaned up soil and groundwater contamination at the four-acre former tank farm site in 2016, two years after ground tanks were removed, according to Ecology.

Under an amended order agreement between Ecology and the port that was reached in 2016, the port was required to perform a preliminary site investigation in the submerged lands area.

A report broken up into two phases in 2018 found a number of contaminants at concentrations “that exceed cleanup screening levels,” according to the 2019 agreed order between the port and Ecology.

“Hazardous substances might continue to be released to the Submerged Lands Area from ongoing sources documented by the Historical Review Report,” the order states, “including, for example, via stormwater sheet flow and stormwater and CSO (combine sewer overflow) conveyance systems.”

The King County Waste Water Treatment Division’s South Magnolia CSO Control project was carried out to prevent wastewater and stormwater from being released into Puget Sound and includes an underground CSO pipe running from 32nd Avenue West down along West Galer Street to the Magnolia Wet Weather Storage Facility near Smith Cove. Bahnick said this project has no impact on the Terminal 90-91 complex regarding future cleanup or subarea disturbance.

Under the agreement with Ecology, the port will complete a remedial investigation of sediment at its Terminal 90-91 complex, which provides short- and long-term moorage for fishing and commercial vessels, including a number of cruise ship lines.

Bahnick said the port will be concentrating on the uplands first, where most industrial activity occurred, and the assessment will be a deeper dive than what took place in 2012 and 2016.

“We’re just building on what we’ve done to date, and we’re also building on what the federal government did, because they did a little work out there also,” she said.

She said most contaminants that tested above the allowable amounts were between the two piers.

The port will provide monthly progress reports, and must notify Ecology should it uncover any significant increase in sediment contamination.

Ecology launched a public comment period that started on Oct. 10 and will conclude on Nov. 25. An open house will be held from 3-6:30 p.m. Tuesday, Nov. 5, at the Queen Anne Library, 400 W. Garfield St. An open house at the Magnolia Library took place on Oct. 22, but an Ecology news release was not sent out until Oct. 24. Comments can also be made online.

Once the comment period has passed, Bahnick said, the Port of Seattle Commission will decide whether to approve the agreed order at its Dec. 10 meeting, which she expects will occur. Then the port can move forward with procuring a consultant to develop a draft plan that will then be reviewed by Ecology, the tribes and other stakeholder agencies before final approval.