Geology experts believe MTBE cleanup is adding to problem
March 17, 2003
A group of geology experts believes MTBE cleanup work overseen by regional water quality experts has increased contamination caused by the fuel additive.
The critics, an engineer and one of the top geophysicists in the country, are focused on wells drilled by environmental consultants at the “Y.” They say wells drilled at a gas station ignored a layer of silt and clay that provides protection to groundwater.
Engineer Craig Morgan and geophysicist Graham Kent say the consultants drilling through the silt and clay sent MTBE deeper into groundwater and increased the cost of the cleanup by millions of dollars.
Members of Lahontan Regional Water Quality Control Board deny the accusation, stressing the fact that consultants were required to use a probe to do less invasive groundwater sampling at the cleanup site before drilling any wells.
The monitoring wells, about 90 small holes, were punched in the ground to determine how far MTBE spread from underground tanks at the USA gas station. Today the station at 1140 Emerald Bay Road is called American Gasoline.
Morgan, a civil engineer and environmental consultant, said the probing is immaterial because such wells were drilled at USA gas as early as 1985.
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The wells detected MTBE in groundwater as far as a half mile from the station in 1998. Today the MTBE plume is about a half block from the station and is considered by Lahontan to be about 90 percent cleaned up.
“They just kept doing it and doing it,” said Morgan, of monitoring wells approved by Lahontan. “It would have been a $1 million cleanup, now it’s a $4 million cleanup.”
Morgan says in the mid-1980s when he worked at Lahontan as a water resource control engineer, he had heard groundwater at the “Y” was confined by a layer of sediment. It wasn’t until 1999 that he stumbled onto evidence that the layer exists. Morgan was doing MTBE-related consulting work in the South “Y” area at the Tahoe Verde Mobile Home Park.
While drilling about 30 feet underground, Morgan said he discovered a 1-to 3-foot layer of silt and clay while drilling a hole as part of his investigation. Water immediately drained below the layer “like pulling a plug on a bathtub.” Morgan immediately plugged the hole with clay. The event meant one thing, water was perched on an underground layer, Morgan said.
“Even if they don’t agree with the contentions, it’s incumbent on (Lahontan) to go and check it out,” Morgan said. “But they never did. Their argument is that (the layer) is not continuous. But all the evidence points … that it is.”
The evidence, Morgan says, comes in seismic data collected from the lake, cores of earth pulled from the ground, geology reports written in the late 1960s and 1970s, and from data collected that show varying water levels above and below the silt and clay layer, as well as varying chemical compositions of the water.
Morgan said he has presented the information to the Lahontan Regional Water Quality Control Board several times in the last two years. Each time, he says, staff rebuffed his claim.
“We looked at a lot of stuff” in response to Morgan’s claims, said Chuck Curtis, Lahontan division manager.
Curtis cites a 110-foot earth sample taken by consultants at the Shell station at the “Y” not far from American Gasoline, as evidence that there is not an impenetrable layer of material that runs across the South “Y” area.
“I was out there on the ground looking at the (sample),” Curtis said. “It’s not a clay layer.” Curtis and Tom Gavigan, an associate engineering geologist at Lahanton, say the sample of earth showed about 1 foot of silty sand, which MTBE-laced water could easily flow through.
Kent, a geophysicist at the Scripps Institute of Oceanography in San Diego and classmate of Morgan’s at South Tahoe High School, says the debate over whether the layer is silt or clay is not important, and in general, Lahontan has missed the point.
“Whatever you want to call it, the question is, does it prevent the vertical flow of water?” Kent asked.
“They basically are close-minded and ignorant,” Kent said. “We’ll find a way to show them that not only their practices but their attitudes are endangering the future water supply of the Lake Tahoe region.”
Kent said he plans to look for funding to create pictures through seismic imaging of South Shore’s underground. Lahontan says it would welcome the work.
“I’d love for them to do it,” Curtis said.
In August, the South Tahoe Public Utility District reached a $69 million settlement after suing a number of oil companies for selling MTBE-laced fuel at South Shore. In all, 15 of STPUD’s water supply wells were shut down because of MTBE, or methyl tertiary butyl ether, which makes drinking water taste and smell like turpentine.
Jurors awarded the money in the settlement after they found the oil companies’ product to be defective. MTBE has since been banned from use at the basin and it’s being phased out throughout California.
Graham Fogg, professor of hydrogeology at UC Davis, testified as an expert witness for STPUD at the trial. Fogg, who wrote a landmark report on MTBE for the governor in 1998, said his groundwater models for the “Y” area didn’t work until he factored in the presence of some type of less porous layer.
“There’s no such thing as material that’s a completely impervious layer, especially in a sedimentary basin like Tahoe,” Fogg said. “Layers like that do delay downward movement. I don’t believe cross contamination by drilling is the dominant cause of the overall MTBE problem. I strongly suspect that sort of thing can exacerbate the problem.”
Ivo Bergsohn, hydrogeologist at STPUD since MTBE became an issue at South Shore in 1998, said he doesn’t believe the information presented by Morgan and Kent, if proven true, would have influenced the outcome of the lawsuit.
“As far as information from Graham Kent … he contacted me in the summer of 2002,” Bergsohn said. “I can say it was never presented to us in any great detail, but it didn’t look like it would have had great bearing on what was being presented as far as the lawsuit goes.”
Last month, with the STPUD lawsuit a done deal, Kent, Morgan and a number of geology experts attended a meeting to discuss groundwater at South Shore in an effort to disseminate information. Bergsohn and five staffers from Lahontan attended the meeting. Lahontan said it found some information interesting, but that they don’t expect to do anything differently as a result of what they heard at the meeting.
Dennis Parfitt, a contamination expert at the State Water Resources Control Board, also attended the meeting. At the request of a consultant at Tahoe Tom’s, a South Shore gas station near Stateline with MTBE contamination, Parfitt conducted a preliminary investigation into the groundwater of the area. He concluded there were a number of pockets of confined layers of water that had been penetrated by monitoring wells and that likely caused MTBE to dive deeper into groundwater.
Parfitt, however, said it’s not unusual to find MTBE contamination has been made worse through cleanup efforts. Often environmental consultants bid the lowest price to get the contract and don’t make the effort to gather the information needed to treat contaminated groundwater correctly.
“We’ve seen in many parts of the state, not only in Tahoe Basin, the (cleanup) phase can exacerbate environmental impacts to the site rather than making it better — just by the way monitoring wells are constructed,” Parfitt said. “We’ve seen that in Orange County, Los Angeles, Santa Barbara, Napa — just about everywhere you look where there is a gasoline investigation.”
— Gregory Crofton can be reached at (530) 542-8045 or by e-mail at firstname.lastname@example.org