MTBE cleanup a highly costly venture
It’s a monster at least as big as two city blocks.
It has crept beneath Lake Tahoe Boulevard, Park Avenue, the Black Jack Motel, Ski Haus Lodge, Paradise Motel and other businesses.
It is a long, fat pool of gasoline contaminants – largely made up of MTBE – that has infiltrated the groundwater underneath Tahoe Tom’s service station.
The plume hasn’t contaminated any drinking water wells yet, but there are plenty nearby that are at risk.
Even with MTBE-free gas coming to Lake Tahoe and new rules for underground storage tank systems, South Shore’s problems with groundwater contamination likely will exist for years.
The reason: Expensive cleanup.
A prime example is Tahoe Tom’s. The Lahontan Regional Water Quality Control Board took over cleanup there in July, after the owner had already spent his $1 million allocation from the state. Experts predict it will cost another $4.2 million to finish the job.
Tahoe Tom’s is the second station in the basin Lahontan has had to take over the cleanup for, and it probably won’t be the last.
“It’s going to take more than a million dollars to clean up these MTBE sites,” said Lisa Dernbach, associate engineering geologist for Lahontan. “The governor issued his directive in March, but that will only take it to $1.5 million (per station), and that doesn’t go into effect until January 2000.
“No one had any idea how much it would cost to clean up these MTBE sites. Down in Santa Monica, where the worst MTBE contamination in the state is, it’s going to cost $10 million to clean up one Mobile station. We’re learning all the time just how expensive this is.”
The former USA station by the “Y” has a larger contamination plume than at Tahoe Tom’s, and there are three remediation systems set up to fight that plume. However, Tahoe Tom’s has the biggest single-site remediation system in the Tahoe Basin.
Eight groundwater wells have been drilled at the station and on nearby properties. The wells pull contaminated water from the ground, and the tainted water travels to the station in underground pipes. There, the water goes through an 18-foot-tall, air-stripping tower, which cleans 90 percent of the contamination. A carbon-filtration system also is housed behind the gas station, and that takes out the rest of the contaminants.
After it is cleaned, the water is released into South Shore’s sewer system. Lahontan has to pay the South Tahoe Public Utility District in order to do that.
But that isn’t all.
An “air sparge/soil vapor extraction system” also is housed at Tahoe Tom’s. It cleans the soil contamination – not groundwater contamination, which the air-stripping system addresses – directly beneath the station. The system essentially blows air into the soil, which vaporizes the gasoline. Then a vacuum pulls the gaseous contaminants out of the ground.
Consultants this week are drilling what Dernbach calls “guard” monitoring wells beyond what Lahontan believes is the extent of the plume. Those wells will tell whether the plume has continued to spread. If it has, wells belonging to a nearby hotel and the Lakeside Water Utility District will be in danger.
STPUD has two wells in the area that have been shut off to avoid pulling in the contaminant plume. Groundwater – and MTBE – can move up to three times faster than normal when near a pumping well.
Unlike STPUD, which has dozens of other wells, Lakeside and the hotel don’t have the luxury of being able to shut their wells off, Dernbach said.
STPUD has turned off more than a third of its well because of MTBE contamination.
If the Tahoe Tom’s plume has spread to the guard wells, Lahontan will have to build another remediation system – identical to the one already at Tahoe Tom’s – somewhere near Park Avenue.
“If those do show contamination, we’ll have to move a lot faster,” Dernbach said. “We hope the plume has been pulled back, but we’re not sure.”
Soil underneath Tahoe Tom’s was contaminated in the 1980s, and gas station operators had been cleaning it for years. More contamination started showing up in 1996, but the station’s operators said they thought it was the old plume. When levels of MTBE continued to increase, Lahontan knew there had been more gasoline released.
No leak was discovered. What officials believe happened was workers were over-filling the underground storage tanks. Like when filling up an automobile’s tank, there is an automatic shut-off valve to stop the gas from overflowing. This one wasn’t working.
The overflowing fuel poured into the soil beneath the station, and more than 400 gallons of gasoline collected under Tahoe Tom’s.
All underground storage tank owners in the nation were required to install alarms by 1999 that would have notified officials the overflows were happening. In 1996, however, there had been no legal requirement for Tahoe Tom’s to have it installed.
Lahontan has fined Tahoe Tom’s $131,000 for delinquent cleanup efforts, and the owner can try to appeal that action to Lahontan’s board.
The decision-making board for Lahontan meets next week for the first time since 1998. The meeting will start with a tour of the cleanup system at Tahoe Tom’s on Sept. 8. The public is welcome.
What: Lahontan tour of contamination cleanup system
When: Sept. 8, 3 p.m.
Where: Tahoe Tom’s, 4029 Lake Tahoe Blvd.
Information: (530) 542-5400
What is MTBE?
Methyl tertiary butyl ether is a gasoline additive that has contaminated as many as 14,000 groundwater sites in California. The U.S. Environmental Protection Agency classifies it as a possible cancer-causing agent. At low levels of contamination, it makes water undrinkable. MTBE-laden water smells and tastes like turpentine.
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