Yankee's new wells delayed

Posted Thursday, September 2, 2010 10:18 pm

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BRATTLEBORO -- The drilling of five new groundwater monitoring wells at Vermont Yankee nuclear power plant in Vernon has been delayed awaiting the completion of an engineering assessment.

"We don't dig any holes at the plant without one," said Larry Smith, Yankee's director of communications, adding the drilling has been delayed by 15 days. "We do a detailed review before we start doing any work on site."

The new wells are to be located next to buried underground pipes that run from the Advanced Off-Gas Building to the plant stack, according to information posted on the Vermont Department of Health's website.

In January, Entergy, which owns and operates Yankee, told the DOH that tritiated water had been discovered in a groundwater monitoring well on-site.

The leak was traced to a pipe tunnel adjacent to the off-gas building. The leak was due to a clogged sump pump. After the sump was cleared in February the leak was stopped.

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As of Aug. 26, approximately 245,000 gallons of tritium-contaminated groundwater has been pumped out from the site from three extraction wells. Entergy has set a goal of removing 300,000 gallons of contaminated water to help remediate soils.

The current concentration of groundwater being removed is in the 76,000 picocuries per liter range.

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Entergy has another extraction well that may soon be operational, according to the DOH. This new well would make it possible to extract groundwater with tritium concentrations near 370,000 picocuries per liter, stated the DOH.

Entergy will also install at least two new sampling pumps in an on-site drinking water well that was taken out of service shortly after the leak was discovered.

At no time, said Smith, was tritiated water discovered in the 360-foot-deep well. Tritium at the site has been found at a depth of 25 to 30 feet, while the drinking water well is 12 times as deep.

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The new pumps will be at different levels to monitor the possible downward migration of contamination.

Entergy has also been sampling other drinking water wells on and off site, said Smith, with not tritium contamination being detected.

According to the DOH, the Nuclear Regulatory Commission is still inspecting Yankee's groundwater protection program, a review it hopes to finish by Sept. 13.

Hydrogeological testing is being conducted to determine the bedrock and soil conditions beneath the plant.