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State, LANL focus on chromium plume cleanup

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By Tris DeRoma

Containment and cleanup of a decades-old chemical spill on Los Alamos National Laboratory property has taken top priority with the state’s Environment Department and LANL.
At a public meeting Wednesday, representatives from the New Mexico Environment Department and the Environmental Management Los Alamos Field Office explained waste cleanup priorities recently worked out in a revised consent agreement between the state and the Department of Energy.
Their top priority for 2017 is to start the containment and eventual cleanup of an underground plume of chromium, a corrosion preventive used in cooling towers at a laboratory plant between 1956 and 1972.
Water containing the chromium was routinely flushed out into Sandia Canyon, where it eventually settled into an aquifer under Mortandad Canyon. At one time, about 80 tons remained beneath the canyon when the lab started addressing the problem in 2005, with a monitoring program involving 20 monitoring wells planted at various depths in and around the plume.
David Rhodes, director for the office of quality and regulatory compliance at the Environmental Management Office in Los Alamos, described the plume as being circular, a half-mile in diameter and about 250 feet from a water table in the area.
While the lab has taken steps to clean up the chromium and contain it, the chromium plume has slowly moved toward the San Ildefonso Pueblo.
No drinking water sources in Los Alamos or the pueblo have been affected by the plume, officials said.
Rhodes explained Wednesday what the office was doing to slow down the migration and eventually clean it up.
“We are about to go turn on the interim measures in order to go and retard or prevent further migration of the chromium plume off laboratory property,” Rhodes said.
For the past year, workers have installed a network of pipes and five wells along the boundary of the plume. The plan is to use the wells to pump clean water back into the boundary to slow the spread until the Environmental Office and NMED figure out a solution.
About $90 million of an $184 million annual toxic waste cleanup allocation from Congress was spent on priorities listed in the consent agreement, with about $26 million of that $90 million spent on the chromium cleanup.
“This is by far our single biggest bucket of money in order to put all this infrastructure in, to go and finish the testing, take the interim measures. This is what’s driving most of the EM funding at this point,” Rhodes said.
Bruce Robinson, program director for environmental remediation with Los Alamos National Security, the managing and operating contractor of the lab, said previous monitoring has given them fairly accurate knowledge about the plume’s dimensions.  
One monitoring well on San Ildefonso land has shown the chromium has not reached that location.
“Computer modeling (of the chromium migration) is expecting it to show up in a year to one-and –a-half years if we do nothing, So we are taking this action so it doesn’t show up as high as it could,” Robinson said.
A final solution to total cleanup has not yet been worked out. Rhodes said that’s going to involve further talks with NMED.
“We haven’t gotten there yet,” Rhodes said. “We have to go through the characterization of the CME (Corrective Measures Evaluation) before we can even make a proposal on what we think of should be done. So right now, there are no milestones for chromium final remedy,” Rhodes said. He said the actual clean up of the site is probably a couple of years out.