Courtesy of LANL
Monitoring wells help scientists keep tabs on a plume of chromium.
T en years ago, Los Alamos National Laboratory discovered a problem creeping its way through lab property. A plume of hexavalent chromium—of Erin Brockovich fame—had drifted down the canyon from an old power plant.
Recent testing by the US Department of Energy shows increasing concentrations of chromium at the edge of the plume, indicating that the material is still moving and has likely breached the lab boundaries.
Chromium comes in a variety of forms. The US Environmental Protection Agency lists chromium-3 as an "essential human dietary element" that can be toxic in high concentrations, while chromium-6 is known to pose health risks even in small amounts and may also be linked to cancer.
The lab unloaded up to 160,000 pounds of chromium after it was used in the power plant's cooling tower water to slow corrosion, and now, some of the contaminant is sitting in the top 50 to 75 feet of the aquifer that serves residents of Los Alamos County. It's also moving on land long considered sacred within the jurisdiction of San Ildefonso Pueblo. Pueblo officials did not respond to repeated requests for comment, but the county doesn't seem to be worried.
"We're testing continuously," says Julie Williams-Hill, public relations manager for Los Alamos County. "LANL takes the lead doing the testing for us, and they do it in such a way that if any of the testing is of concern, we would have ample time to stop drawing water from that well, and they would drill us a new well."
So far, Williams-Hill notes, levels of chromium in the county well have tested at 2.29 to 13 ppb, well below the drinking water standards.
The lab had previously claimed that its so-called legacy contaminants—from researching the materials to make the world's first nuclear bombs, and other tasks—sat on a layer of impermeable rock. But after a state-ordered hydrogeologic survey, which uncovered the plume, it's clear that's not the case. Crazy straw-like fissures lie within the landscape, and one of them allowed the chromium plume to drop into the aquifer.
Joseph Johnson
A decade lapsed between when the chromium was found and the publication of a plan to address it, but it's taken some time to wrap their arms around the problem, says Danny Katzman, technical lead for LANL's chromium project, pictured at right. The lab's aim, he says, is to slow the drift for now. Eventually, they hope to neutralize the contaminant in place.
"Our understanding of the plume, where it is and how it's moving has really only matured in the last year," Katzman says. "It's kind of a typical evolution of a complex environmental problem."
EPA standards say the safe level for chromium of all types is 100 parts per billion, but the New Mexico Environmental Department sets the standard for drinking water at 50 ppb. (In a post-Brockovich choice, for comparison, California's Office of Environmental Health Hazard Assessment set a goal specifically for hexavalent chromium in drinking water of 0.02 parts per billion.)
Testing in the plume has found chromium levels as high as 1,000 ppb. That info comes from about 20 monitoring wells that keep tabs on underground contamination estimated to encompass an area of about a mile by one-half mile. Exactly how far chromium now stretches past the lab boundary isn't clear, but researchers infer from the changing concentrations that the plume is still moving.
A southern monitoring well near the boundary with San Ildefonso Pueblo has been showing increasing levels of chromium, which has made the matter all the more pressing. Did it move faster than they expected? Katzman says the lab really hadn't set expectations for how quickly it would move. But the time is now to act, and they hope to begin mitigation work, pending state approval, this fall.
The Department of Energy proposes to gain control of the plume, perhaps even drawing it back over the boundary line, with an eight-year project that will see up to 1.8 billion gallons of chromium-contaminated water extracted from 1,000 feet underground through three wells, cleaned and then spread over the land, allowed to evaporate, or returned to the depths from whence it came through six injection wells. A similar model is in use at a Superfund site in the central business district in Albuquerque, where contamination from a defunct dry cleaning facility stretches ⅔ of a mile long, and at the bulk fuels facility on Kirtland Air Force Base, where a jet fuel leak has required 8.2 million gallons of water be treated.
It's impossible to know exactly when the Los Alamos chromium was released from the power plant 3 miles up Sandia Canyon. Officials say it happened sometime between 1956 and 1972. Then, surface water likely carried the material down the canyons to where the geology was permeable enough to allow it to settle underground, reaching the top layer of the aquifer. The surface water in that area now is clean, Katzman says, leading them to believe that they've caught the tail end of the plume.
That doesn't cue peace of mind for everyone keeping an eye on the project, which includes the Northern New Mexico Citizens' Advisory Board and Nuclear Watch New Mexico.
"The fact that it's 1,000 parts per billion 3 miles from where they dumped into the canyon is kind of scary, because it seems like there might be a lot of it out there," says Scott Kovac, operations and research director for Nuclear Watch New Mexico. "Chromium is very soluble; it's an indicator, like a canary in a coal mine…They dumped chromium in the upper part of Sandia Canyon from the '50s to the '70s, and it's already in the aquifer, so you can't tell me that the rest of the stuff [won't get there, too]."
Ultimately, for all possible contaminants still stored on site at LANL, Kovac adds, "The conclusion has to be to remove all the sources."
