All parties agree that the old Malarkey asphalt plant on the Duwamish River in South Park needs an environmental cleanup, so the bone of contention now is, how clean does it have to be?

The U.S. Environmental Protection Agency must clean the site enough so the land can be used again for whatever the zoning allows. In this case, the former asphalt plant site is zoned for industrial use.

On the other hand, some South Park residents and the Seattle City Council want the former asphalt plant site cleaned more thoroughly, so it could become a park or even a residential neighborhood some day.

The site, also known as Terminal 117, is owned by the Port of Seattle.

The pollutant of most concern at Terminal 117 site is polychlorinated biphenyl (PCB). It is a man-made coolant formerly used in electrical transformers. A known carcinogen, PCB production was outlawed in the U.S. nearly 30 years ago.

The federal limit in an industrial area is 25 parts PCB to every 1 million parts soil.

Samples taken at the South Park site showed 4,500 parts PCB for every 1 million parts soil. At the north gate of the former asphalt plant, they found 9,200 parts per million.

The other pollutant of concern at Terminal 117 is waste oil.

Asphalt is a bituminous substance that's mixed with gravel or sand to repave roads, parking lots and pathways. Asphalt is found naturally in large flat beds.

Asphalt also is manufactured by refining petroleum and that's how they made asphalt at the South Park plant. The process required heat to cook the petroleum so they burned waste oil, which contained polychlorinated biphenyl. There is PCB all over the plant site as a result.

"EPA (Environmental Protection Agency) decided to remove the soil as soon as possible before the rainy season," said Sheila Eckman, Superfund unit manager manager for the Seattle office of the Environmental Protection Agency.

Approximately 2,000 tons of contaminated soil was removed from the plant site in 1999, said Riva Sanga, project manager for the Environmental Protection Agency. The federal regulatory agency put the lower Duwamish River on its Superfund list along with the nation's most polluted areas. It was added to the national priority list in 2001.

More PCB was found in adjacent property in 2004 and 2005.

The EPA proposes to scrape the top 2 feet of soil off portions of the plant site. In some places, excavation would go down about 10 feet because the pollution is located at different levels of the soil, said Wayne Grotheer,manager of corporate environmental services for the Port of Seattle. The goal would be to reduce PCB contamination to a standard of 10 parts per million in the top 2 feet of soil, and 25 parts per million deeper than 2 feet.

Approximately 11,000 cubic yards of contaminated dirt would be removed - about 11,000 dump truck loads - which would be hauled to a landfill for contaminated soils in Eastern Washington.

Clean fill dirt would be trucked in to replace the contaminated soils and then the plant site would be covered, somewhat ironically, with another asphalt cap to prevent rainfall from penetrating into the ground.

The Environmental Protection Agency plans to clean up the plant site this summer, Eckman said. Meanwhile the river bank at the Malarkey site and the adjacent river sediments would be cleaned up next year, she said.

Despite the Environmental Protection Agency's plans, the Seattle City Council and many South Park residents are urging that the plant site be cleaned to the point where it could be redeveloped for other uses.

Just as in White Center, the city of Seattle is considering annexing part of South Park that is still unincorporated. The asphalt plant site is part of the unincorporated "sliver by the river."

In a May 25 letter to the Environmental Protection Agency's regional office in Seattle, all nine members of the City Council urged "ensuring that the land is clean enough to be used for any zoning designation that the city may determine appropriate."

The City Council pointed out that the property is bordered by land zoned for commercial and residential zoning. It's also adjacent to the South Park residential urban village.

At a May 25 public meeting at Concord Elementary School in South Park, people held signs stating, "Parks, not parking lots," "Clean up our South Park" and "People not toxic waste."

A woman at the meeting worried that the cleanup would be done piecemeal, with some work this year and more to be done at an unspecified future date. She cautioned that the pollution is in the intertidal zone, and the Seattle earthquake fault runs nearby. She urged authorities to clean up all of the contaminants at once and thereby stop the pollution at its source.

A man at the meeting recommended cleaning up the site's "hot spots" now and returning later "to do this right."

Cleaning the asphalt plant site to the point where its soil would have no more than 1 part per million of polychlorinated biphenyl could triple the amount of soil to be removed, said Anita Lovely of Lovely Consulting Inc. She is an environmental scientist who's managed environmental cleanups for 25 years. She participated in a panel discussion at the May 25 meeting.

One person in the audience asked the scientists if they thought it preferable to clean only part of the site now and then come back later to finish the cleanup.

A complete cleanup doesn't make business sense if the property is to continue as an industrial site, said Wayne Grotheer, manager of corporate environmental services for the Port of Seattle.

As is often the case regarding pollution cleanups, the government will pay private contractors to capture and haul away the contaminated soils. However the Port of Seattle and the city of Seattle have to determine how much ownership, and responsibility, each holds, said David Schaefer, a Port spokesman.

The public entities probably will end up negotiating with insurance companies to determine how much of the pollution cleanup will be paid by the insurance companies representing former owners of the plant site.

Tim St. Clair can be contacted at 932-0300 or tstclair@robinsonnews.com