Cleanup of petroleum-contaminated soil and groundwater at the North Market Street Superfund site is expected to start next year, says Bill Fees, an environmental engineer with the Washington state Department of Ecologys toxics cleanup program.


After years of studying, testing, and monitoring the site, the Department of Ecology and three petroleum companies have reached agreements for a nearly $9 million cleanup project there, Fees says.


The Superfund site is north of Lincoln Road between Market and Freya streets, and includes a former refinery and a fuel storage and distribution center thats still in operation.


The three companies involved in the cleanup agreementsChevron Pipeline Co., of Spokane; Phillips Petroleum Co., of Bartlesville, Okla.; and Tosco Refining Co., of Linden, N.J.have been identified as being potentially liable for contamination at the site, and together have conducted studies on the contamination and possible cleanup plans under agreements with Ecology.


Because contamination at Chevrons property was minor compared with the contamination on the rest of the site, Chevron has agreed to pay Ecology $158,000 for its share of the cleanup costs. Once Chevron makes that payment, it no longer will be considered liable for the pollution unless unforeseen conditions are encountered during cleanup, Ecology says in documents outlining the settlement.


A second agreement with Phillips and Tosco will implement a cleanup plan that Ecology drew up last year based on the studies done by the companies, Fees says.


The cleanup will include excavating the sites top layer of soil, which has been contaminated with gasoline, diesel, and heavy oil, and treating that soil with a heat process to remove the contaminants, Fees says. That work is expected to cost about $4.5 million, he says.


Contamination in deeper soils, up to 60 feet below the surface, will be treated with a process called bioventing. Bioventing involves blowing air into holes drilled deep into the soil to provide additional oxygen to microbes that already live in the soil and can metabolize petroleum, thus removing the contamination, Fees says. That process is estimated to cost about $3 million.


A similar process will be used to treat groundwater contamination, he says. Its estimated that the groundwater cleanup will cost about $1.4 million, Fees says.


Consent decrees, which are legal documents that will formalize the agreements between the state and the companies, likely will be filed at Spokane County Superior Court by year-end, Fees says.


Consultants hired by Tosco and Phillips already have started to develop rough designs of the cleanup systems, and they have 90 days to complete that process, Fees says. Then, the designs will be submitted to Ecology for public review. After Ecology approves the initial designs, detailed engineering work will be completed, and the cleanup project likely will be put to bid next summer, he says.


The North Market sites pollution problems date back to the late 1930s, when several properties in that area were developed as an oil refinery complex.


The Tosco Spokane Terminal continues to operate as a fuel storage and distribution center, with a storage capacity of 391,500 barrels of fuel. Ecology says at least two spills of petroleum products have occurred there since 1976.


Ecology says neighboring landowners reported petroleum-soaked soil at the site in 1978, and in 1984 the state discovered petroleum contamination in groundwater. In 1990 the site was listed as a Superfund site.