On Dec. 23, 2005, the Laboratory reported the discovery of elevated chromium in the regional groundwater in R-28, one of the Laboratory's newest monitoring wells located in Mortandad Canyon. The Laboratory and Los Alamos County have been monitoring community water-supply wells for more than 40 years for a wide range of potential contaminants, including chromium. This finding represents the first time contaminant levels at the Laboratory have exceeded EPA limits in the regional aquifer. However, there has been no detection of elevated chromium levels in Los Alamos community drinking-water-supply wells.
"Under direction of the NMED, the Laboratory has initiated an aggressive investigation of the sources and extent of the chromium contamination," said Ken Hargis, Los Alamos' Environmental Stewardship Division leader. "We are taking this issue very seriously and we will continue to take any necessary actions to protect the environment and human health."
The Laboratory has developed an "interim measures work plan" for the investigation of chromium contamination in groundwater beneath the Laboratory and will deliver it to the New Mexico Environment Department (NMED) by April 3, 2006. This work plan incorporates the most recent sampling results for chromium and proposes a first phase of activities to address the findings. Ongoing and planned investigations, under the direction of NMED, will improve the understanding of the chromium contamination and help focus future work including development of possible remediation measures to limit any potential impact to drinking water.
The University of California has briefed Los Alamos National Security, LLC (LANS), on the data and the investigation work plan required by the NMED. LANS, like UC, is committed to the protection of public drinking water supplies, said Hargis, and will follow through on commitments that DOE and UC are making to NMED in the work plan that will be submitted on April 3.
In January and February, the Laboratory collected groundwater samples from 19 monitoring and supply wells in the vicinity of monitoring-well R-28 to perform tests for chromium. Additional sampling locations included several drinking water supply wells located elsewhere in Northern New Mexico for comparison. Water samples from Northern New Mexico water-supply wells show chromium concentrations that are within normal background concentrations.
The new data confirm that water-supply wells near R-28 are unaffected and show only low levels of naturally occurring chromium that are typical of groundwater in New Mexico and other western states, generally 3 to 5 parts per billion. These concentrations are nearly 20 times less than the EPA drinking water standard of 100 ppb.
The results indicate that the chromium in the R-28 groundwater samples exists predominantly in the hexavalent form. Hexavalent chromium levels in local water supply wells and groundwater in the Jemez Mountain area are consistent with levels elsewhere in the western United States.
Chromium is an element occurring in nature. It is found in surface water, groundwater, rocks, animals, plants, soil, volcanic dust and gases. It is present in the environment in several different forms. Most common are trivalent or chromium III and hexavalent or chromium VI. Trivalent chromium is an essential nutrient for the human body. Hexavalent chromium often occurs as the result of industrial processes, but is also a naturally stable form in groundwater. Chronic exposure to elevated concentrations of hexavalent chromium can affect human health.
Sources of man-made chromium contamination include corrosion of stainless steel, chrome plating, leather tanning, dyes and pigments, and use in water-cooling systems associated with power plants to prevent scaling and minimize biological growth. Use of chromium water-cooling systems at the Laboratory between the 1950s and 1970s is the most likely source of the chromium contamination at the Laboratory. The Laboratory stopped using chromium in cooling towers in the early 1970s.
The Laboratory is working closely with San Ildefonso Pueblo and Los Alamos County to ensure that adequate monitoring of the drinking water supply system is being implemented. If it were to become necessary, drinking water can be treated by different on-line treatment systems, including activated carbon filtration, reverse osmosis, or ion exchange.
Los Alamos National Laboratory, a multidisciplinary research institution engaged in strategic science on behalf of national security, is operated by Los Alamos National Security, LLC, a team composed of Bechtel National, the University of California, The Babcock & Wilcox Company, and the Washington Division of URS for the Department of Energy's National Nuclear Security Administration.
Los Alamos enhances national security by ensuring the safety and reliability of the U.S. nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction, and solving problems related to energy, environment, infrastructure, health, and global security concerns.