Residual gas and petroleum from past spills at a fuel terminal near Sacajawea State Park have been cleaned up to the point that nature can take care of the rest, according to state officials.
The state Department of Ecology is accepting comments until Jan. 31 on the agency's decision to allow natural biodegradation to finish cleaning up remaining contaminants at Chevron Pipe Line Co.'s bulk fuel terminal.
Both Chevron and Tidewater Terminal Co. have aggressively responded to past spills on the 33-acre Pasco site, said Bill Fees, a state environmental engineer. Both companies have installed systems that have cleaned up contaminants to the point where the concentrations are beginning to flat line, he said.
"The contamination is not only decreasing, it's also not going anywhere," he said.
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Fuel from the property owned by Northwest Terminalling Co. is transported through pipelines from Salt Lake City to Pasco and then is moved to other locations by truck, barge or pipelines. The property has been used to store fuel since 1950.
In the mid-1980s, petroleum was discovered in groundwater monitoring wells on the site, and a oil sheen was seen along the bank of the Snake River. A Chevron-owned pipe that transferred aviation fuel was leaking, and it, along with contaminated soil and fuel products, were removed. Chevron added clean soil to the site and along the shoreline and monitoring increased.
In 2000, workers discovered gasoline leaking from a hole in the Tidewater transfer pipe that moves fuel to Chevron, according to the state. About 42,000 gallons were spilled, and nearly all the gallons were recovered, according to the state.
Bill Collins, Tidewater's director of environmental, health, safety and security, said in an email that the company is pleased that remediation efforts have successfully reduced the concentrations of contaminants in the groundwater.
Collins said Tidewater will continue to monitor groundwater conditions to make sure the desired cleanup levels are achieved.
Tidewater and Chevron are required to monitor the site until the cleanup levels are reached for a whole year in a row, according to the state. Fees said there is a plan in place now for that monitoring for up to five years, and if necessary, monitoring could continue even longer.
Both companies also will maintain barriers to limit access and land uses on the property, according to the state.
Cleanup levels will be reached when the concentrations are low enough that they are considered safe for contact or ingestion, Fees said.
The decision to allow nature to take the lead in finishing the cleanup efforts protects human health and the environment, Fees said.
Residents at the nearby Lakeview Mobile Home Park get drinking water from the city of Pasco's system, which is not affected by groundwater at the terminal.
Monitoring has shown that the ground water from the property doesn't flow into the Snake River, according to the draft study. Most of the wells tested already meet state standards.
Through the years, cleanup has included soil vapor extraction, where contaminants in the soil are vacuumed out of the ground and then treated; and air sparging, where air is injected into ground water using blowers and injection wells and the contamination transfers to the air bubbles.
Chevron officials said they had nothing to add to the state's comments.
For the draft study and more information, go to 1.usa.gov/pascocleanup.
Comments can be sent to William J. Fees, WA Department of Ecology, 4601 N. Monroe St., Spokane, WA, 99205-1295 or email firstname.lastname@example.org.
-- Kristi Pihl: 582-1512; email@example.com