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caption: The Quendall Terminals Superfund site (foreground) and Lake Washington with Mercer Island and Seattle in the background
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The Quendall Terminals Superfund site (foreground) and Lake Washington with Mercer Island and Seattle in the background
Credit: Environmental Protection Agency

What to do with toxic waste next to Lake Washington? Burn it underground

Sandwiched between the Seattle Seahawks’ practice fields in Renton and a tract of waterfront townhouses is a rare stretch of undeveloped shoreline, with trees and shrubs dominating the view from Lake Washington.

But a little slice of paradise, it’s not.

Oozing beneath the property and into the nearby mud beneath Lake Washington are creosote and other oily carcinogens, leftovers from many decades of heavy industry at the now-idle site known as Quendall Terminals.

The Environmental Protection Agency is proposing to remove that toxic goo from the ground by burning it.

“No open flames, but very high temperature,” EPA spokesperson Bill Dunbar said. “It essentially combusts the material underground and we would then vacuum out the byproducts, leaving essentially clean dirt."

A bit like charcoals smoldering in a grill, the relatively new combustion technique comes from one Canadian company, Savron Solutions (slogan: “smoldering solutions”).

“It works faster and to a dramatically higher environmental standard than common hazardous waste disposal practices,” Savron marketing materials state.

“We want to prevent any further migration of the contaminants into the lake and want to be sure that when this area is redeveloped, that as much of the contamination [as possible] has been removed to remove any risk to people,” Dunbar said.

The current owners of the Quendall site, who would be at least partially responsible for paying for the cleanup, oppose the combustion plan.

“There’s a lot of red flags there,” said Robert Cugini, one of the landowners with Altino Properties in Renton. “They vastly underestimated the cost of doing the remediation in this manner.”

Cugini’s family owned the Barbee Mill, the last sawmill on Lake Washington, adjacent to the Quendall Terminals property and its creosote plant. In 1970, when the Quendall site was already heavily polluted, they bought it, partnering with a family that ran a wood-treatment plant where the Seahawks training facility now stands.

“Other than the contamination, it's a beautiful piece of property,” Cugini said. “It's one of the largest undeveloped pieces on Lake Washington.”

The families plan to build about 700 homes on the property, once it’s cleaned up.

For most of the 20th century, the wood-preservative creosote was manufactured at the site. Coal tar residues generated at the gasworks on Seattle’s Lake Union (now Gasworks Park) provided much of the raw material.

In the 1970s, crude oil and other petroleum products were stored at the site.

Thick, toxic liquids have tainted the soil and nearby lake sediments ever since.

The EPA declared the area a Superfund site, making it a national priority for cleanup, in 2006.

Last year, the EPA and Savron tested the smoldering technology at the Quendall site. They inserted heating elements and forced air more than 12 feet underground to ignite a slow burn that advanced about a foot and a half per day through the buried petrochemicals.

“An extraordinarily high percentage of the contamination that we targeted was indeed combusted underground and eliminated,” Dunbar said.

“It wasn't as great a success as EPA would lead you to believe,” Cugini said.

Tim Flynn, a geologist who is consulting for Cugini, said the site’s geology is too complicated for the underground burn to work well.

“Think of a layer cake of fine grain soils and coarse grain soils,” Flynn said. He said blowing enough air into the ground to keep the toxic crud burning would be difficult.

“It can be done, but it’s extremely costly,” Flynn said.

The EPA estimates the cleanup, both underground and beneath Lake Washington, would cost $106 million and take about five years with its preferred methods.

Dunbar said combustion wouldn’t work for the pollution that has already reached Lake Washington. The EPA is proposing a more traditional approach there: dredge and remove contaminated mud from the bottom of the lake and smother areas of the lake bed with sand and gravel.

Vulcan Real Estate, which owns the neighboring Seahawks training facility on a former toxic-waste site, declined to comment. The Seahawks did not respond to interview requests.

The EPA is taking public comment through Friday, Nov. 8 on the proposed Superfund cleanup. It aims to have a final cleanup plan in the spring.