City takes fight to MTBE plume
After a month-long free reign, an insidious monster under two South Lake Tahoe city blocks is again going to have a fight on its hands.
The Lahontan Regional Water Quality Control Board is set to begin cleaning up a dense plume of gasoline compounds that has polluted the ground under Tahoe Tom’s gas station.
Lahontan had been cleaning the site since July 1999. On Jan. 25, however, Lahontan had to stop its work. The reason for the stoppage was action by the South Tahoe Public Utility District, a water supplier which has lost the use of more than a third of its wells because of gasoline pollution and has two wells threatened by the plume coming from Tahoe Tom’s.
“It’s unfortunate that the district required us to shut the system down,” said Chuck Curtis, chief of Lahontan’s underground storage tank unit. “With the system not running, there’s likely additional migration of contamination that threatens not only STPUD’s Black Rock wells, which they haven’t been using for quite some time, but also a Lakeside Mutual Water Company well and some private wells in the area.
“We’re very concerned. That’s why we’re trying to get an interim plan together.”
Several South Shore gas stations clean up their MTBE contamination by pumping the polluted fuel out of the ground, treating it and then releasing it into the sewer system. To put the clean water into the sewer, the stations need special permission from STPUD, the area’s primary sewer and water provider.
About a year ago, however, STPUD discovered that the Tahoe Tom’s station – the cleanup of which was not yet handled by Lahontan – had been having breakthroughs, meaning MTBE broke through carbon filters used in cleanup. MTBE-tainted water went into the sewer, and STPUD’s process of recycling its waste didn’t take the suspected carcinogen out.
Contaminated recycled water was shipped through a 26-mile pipeline out of the basin to a reservoir in Alpine County, where the water is used to irrigate thousands of acres of ranch land.
To guard against the problem’s happening again, STPUD required stations releasing treated water into its sewer to better test for breakthroughs. And the district required each of them to sign indemnification clauses, which would protect STPUD from possible litigation.
Lahontan has two problems: There have been two MTBE breakthroughs at Tahoe Tom’s since the agency took over, and the state of California rarely will indemnify itself.
STPUD in January ordered Lahontan to stop releasing the treated water into the sewer.
There is one other station in the basin, the Meyers Beacon, where Lahontan is doing cleanup.
Curtis said the state agency plans to start shipping the treated water from Tahoe Tom’s – about 14,000 gallons a day, or four to five truck loads – to the Meyers Beacon. There the treated water isn’t discharged into the sewer but into a stormwater retention pond. Curtis said the basin has the capacity to handle Tahoe Tom’s treated water, too.
In the meantime, Curtis said, the state is trying to get permission to start discharging into the sewer again. Shipping the water will cost five to six times as much as putting it into the sewer – $12,000 a month compared to $2,160 a month.
Dennis Cocking, STPUD information officer, said the district will not allow discharges into the sewer until Lahontan addresses the district’s requirements.
Lahontan is the only regional board in California which has taken over MTBE cleanup at gas stations.
Tahoe Tom’s, located at 4029 Lake Tahoe Blvd., has had contamination problems since the 1980s. Gas station operators had been cleaning it for years when more contamination showed up in 1996. After Tahoe Tom’s had spent $1 million on cleanup, exhausting its resources, Lahontan took over remediation. The state has spent more than $800,000 there; the total cleanup bill likely will exceed $4 million.
Tahoe Tom’s is one of the few service stations at Tahoe still serving MTBE-laden fuel.
Agency officials admit the cleanup system there is still inadequate, and Curtis said work is under way to try to improve it.
There are other contamination plumes at Tahoe that are larger. However, the one under Tahoe Tom’s is unusually dense with gasoline compounds, especially MTBE. While MTBE levels of 5 parts per billion can render water undrinkable, the stuff being pulled out of the ground at Tahoe Tom’s is 22,000 parts per million.
STPUD has two wells in the area that have been shut off to avoid pulling in the contamination. MTBE can move up to three times faster than normal when near a pumping well.
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