MTBE-contaminated water treated, used
A well polluted by trace amounts of the fuel additive MTBE is producing uncontaminated water for South Tahoe Public Utility District.
Its purity is being ensured by an innovative treatment system, the first of its kind in the nation used to filter drinking water.
The well, which began operating June 26, is one of eight discovered to be contaminated by MTBE, or methyl tertiary butyl ether. The district closed five other wells to prevent the additive from spreading. The district serves 14,000 homes and businesses at South Shore and owns a total of 34 wells.
Linda Beug, a 30-year South Shore resident who lives in Meyers near the Arrowhead well, said she isn’t worried about drinking water supplied by the district.
“I didn’t realize the well was working at this point,” Beug said. “I’ll still drink the water. It doesn’t bother me if they say it’s safe and they’ve tested it. I think there’s so much other stuff in the water we don’t know about.”
Oil companies in the mid-1990s increased the amount of the additive in their gasolines to reduce automobile emissions. Some supplied gasoline with as much as a pint of MTBE per gallon, said Dennis Cocking, spokesman for the district.
On Monday, Shell Oil, Texaco and another oil company settled an MTBE-related lawsuit filed by the district for $28 million. As a result of that lawsuit, and others filed by the district, $69 million will be available to treat contaminated wells at South Shore.
The new water treatment system filters out the additive by shooting bursts of ozone and hydrogen peroxide into the well water to destroy molecules of MTBE. The cleaning process produces carbon dioxide and water, which are byproducts preferred by some over other treatment methods that leave behind dirty carbon filters.
“There’s no waste stream therefore there’s nothing to haul off,” said Charles Borg, vice president of business development at Applied Process Technology in Pleasant Hill, Calif.
APT, which started six years ago, sold the treatment system to the district and has 10 sites in the country where its technology is treating contaminated groundwater.
The Arrowhead well is at the intersection of Arrowhead and Hopi avenues. It pumps 800 gallons of water a minute.
“The water goes into our system,” Cocking said. “A lot of it is being used in the Meyers area. There is nothing for anybody to be concerned with. If anything, it’s getting more scrutiny than any water does.”
The well is running 24-hours-a-day in an effort to suck out any water polluted by the additive. The district drilled the Arrowhead well after MTBE was detected in two smaller wells at the same site. Those wells were shut down and filled with concrete.
To create a third well at the site, the district drilled into an aquifer, or an underground pool of water, that sits 150 feet deeper than the aquifer tapped for the older wells. A 30-foot layer of clay separates the aquifers, but somewhere traces of the fuel additive got into the third well.
The district shut it down immediately because it has a non-detect policy for MTBE, meaning the water it delivers cannot contain any of the additive.
Monitoring and treatment of water at the Arrowhead well will likely continue for years. Money from settlements with oil companies will be kept by the district in a restricted account and used only for cleanup of the additive.
“It has the potential to last a decade,” Cocking said. “No one knows exactly how long the cleanup is going to take. We have two months to come up with a plan.”
MTBE, which the U.S. Environmental Protection Agency says is a carcinogen, spreads quickly in water. The additive that contaminated the wells at Arrowhead spread from a leaking pipe at the Meyers Beacon, a gas station more than a 1/4-mile away.
The leak was discovered in 1997. Lahontan Regional Water Quality Board is still working to clean up soil and groundwater around the station.
— Gregory Crofton can be reached at (530) 542-8045 or at firstname.lastname@example.org
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