Two more wells in question
Ten are down; two more may have to go.
The controversial gasoline additive MTBE continues to cause problems for the South Tahoe Public Utility District as two more drinking water wells may be threatened.
In the past year, 10 of the district’s 34 wells have been shut down because of the threat of MTBE.
STPUD announced Tuesday that laboratory tests conducted last week indicate that MTBE may be present in its Julie and South “Y” wells. The MTBE plume is believed to be coming from the South Lake Tahoe USA gas station, which voluntarily shut down in August because of the MTBE threat.
The water from the contaminated wells is diverted to an air stripping tower, which is effective in removing low levels of MTBE.
STPUD officials stress that all customers are receiving safe drinking water, said STPUD information officer Dawn Forsythe.
Laboratory testing is normally conducted to find MTBE at 0.5 to 5 parts per billion, according to STPUD. However, testing at 0.2 parts per billion indicates MTBE “may be present” in the wells. California allows MTBE in drinking water up to 35 parts per billion.
More tests continued Tuesday, checking the MTBE amounts in the well and in the water after it is treated by the air stripper. Results should be available later this week.
The Julie well produced 64 million gallons in 1997 and makes a substantial contribution to the Gardner Mountain area, according to STPUD. The South “Y” well has been on standby as a backup source of water for several years.
“We will continue to monitor the situation closely, and if we find any indication that MTBE levels may begin to pose risks to the drinking water, we will close (the wells) immediately,” Forsythe said.
Four wells in the area already have been shut down because of the MTBE threat.
The Tata Lane well No. 4, which is contaminated because of the suspected USA plume, also was connected to the air stripper which successfully treated the water for several months. MTBE levels increased to 37 parts per billion, and small traces of MTBE were found in the treated water. The levels were below California standards, but STPUD shut the well down in July.
The air stripping tower was installed in 1992 to treat another contaminant called PCE, a cleaning solvent of which the source was never found.
Tata wells Nos. 1, 2 and 3 were shut down in August because of the MTBE in the vicinity.
MTBE – methyl tertiary butyl ether – is a gasoline additive that is classified by the U.S. Environmental Protection Agency as a possible cancer-causing agent. At low levels, between 15 and 40 parts per billion, people can detect MTBE in water. It smells and tastes like turpentine.
STPUD and the Lahontan Regional Water Quality Control Board met with the USA gas station’s owners – USA Petroleum out of Agoura Hills, Calif., – last week and demanded more aggressive remediation of the contamination.
Remediation efforts continue at the gas station. However, USA has until Friday to submit a plan for a more accelerated implementation plan for cleaning up the site.
Water-usage restrictions for all STPUD customers have been in place since July.
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