The Laboratory has taken the next step toward protecting Los Alamos drinking water from byproducts of a chromium-based corrosion inhibitor that was discharged into the environment more than three decades ago as part of power-plant operations.
Personnel in the Lab's Water Stewardship Project recently began construction of monitoring well R-35 in lower Sandia Canyon. This regional-aquifer-monitoring well is being constructed upgradient and near Los Alamos County drinking-water-supply well PM-3. The R-35 well will act as a "sentinel" that can determine whether a plume of hexavalent chromium—a component of a corrosion inhibitor used from the 1950s to the 1970s—is approaching the county’s PM-3 well.
Los Alamos County drinking water currently meets all federal and state safe drinking water standards, and no water-supply wells show levels of chromium above natural background concentrations.
The Laboratory is installing the R-35 sentinel well after discovering high levels of chromium in the regional aquifer in a recently installed monitoring well known as R-28, which is located about three-quarters of a mile west (upgradient) of R-35 and county's drinking-water well PM-3.
"Protecting precious resources for future generations is a core value of the Laboratory,” said Susan Stiger, associate director for Environmental Programs (ADEP). "R-35 is an important step in understanding the extent of the chromium contamination and how it is moving. This understanding will help us protect drinking water supplies now and in the future.”
Work on the R-35 sentinel well has been approved by the New Mexico Environment Department and falls under requirements of the Consent Order between the Laboratory and NMED, which guides the Laboratory in cleaning up contaminated sites. The sentinel well will help assess the Laboratory’s hypothesis for how chromium is moving in groundwater.
In response to suggestions from the NMED, the Laboratory is attempting to construct R-35 within the regional aquifer without the use of drilling additives other than potable water. The drilling technique is expected to optimize the well’s ability to gather representative data for groundwater quality. International drilling company Boart-Longyear is constructing R-35 under contract to the Laboratory. The Utah-based company has extensive experience drilling without additives in similar geological formations in Oregon, said Danny Katzman of the LANL Water Stewardship Project (LWSP).
If chromium were to unacceptably impact a drinking-water-supply well, a variety of treatment options are readily available. Proven technologies for chromium removal exist and can be added to existing drinking water wells.
