Scene from Mortandad Canyon on Los Alamos National Laboratory where N3B is working on the Interim Measure for the Chromium Project. Photo Courtesy N3B
Danny Katzman points out facilities in Mortandad Canyon to the Los Alamos Reporter May 20 during a tour of the area. Photo Courtesy N3B
BY MAIRE O’NEILL
Mortandad Canyon on the Los Alamos National Laboratory was a hive of activity May 20 when the Los Alamos Reporter toured the chromium interim measure project with Danny Katzman who has been the technical lead for the chromium project since 2006.
Chromium was used in the past at the LANL power plant and at other industrial sites throughout the country to prevent corrosion in piping. Between 1956 and 1972, it has been estimated that some 160,000 pounds of hexavalent chromium (chromium 6) was discharged through outfalls and ended up sitting on the aquifer where it formed a plume estimated to be about a mile long, a half-mile wide and 50-75 feet thick at the water table a depth of some 1,000 feet below ground.
Some 35 monitoring, extraction and injection wells have been installed in and around the plume initially supporting site characterization and now largely supporting monitoring for what is called the Interim Measure which aims to prevent further migration of the plume until a final remedy is developed. Under the Interim Measure, contaminated water is extracted from a series of wells and run through an ion exchange treatment where it passes over tiny beads that look like caviar and the chromium 6 is removed from the water. The resulting clean water is then injected back into the ground forming a hydraulic barrier along the downgradient edge of the plume preventing it from traveling across the Lab’s southern boundary with Pueblo de San Ildefonso.
This process will continue until the final remedy is identified and implementation begins, hopefully within the next several years. Meanwhile extensive characterization of the area continues. The final remedy will be subject to a public participation process as well as approval by the New Mexico Environment Department.
“It’s like all hands on deck on this Interim Measure,” Katzman told the Los Alamos Reporter. “We’re really trying to push it. We’re coordinating well with NMED. They’re very engaged in the project and everybody seems to be optimistic at this point about the ability to effectively meet the objective of the Interim Measure and gain hydraulic control of the plume.”
He said he thinks the project is working well with active crews out in Mortandad Canyon working to get the other part of the Interim Measure infrastructure up and fully running by this summer and at the same time continuing to work towards the final remedy.
“We continue to work with our regulator on remedy design and conceptual approaches for how to finally take care of the plume. We are also continuing to work closely with San Ildefonso, and with Los Alamos County, making sure that their interests are addressed as well,” Katzman said.
He said in the case of the County, the interest is in ensuring nearby water-supply wells are protected while in the case of San Ildefonso it’s ensuring that the plume will be maintained well within the Laboratory property. He said the relationship with the state on the Interim Measure is very good.
“They are very engaged in the project. We try to communicate quite frequently on the details of how things are operating such as what’s working, how much water is being extracted and injected. We have quarterly reports that we issue to the State. It’s a very transparent project and one we’re proud of,” Katzman said.
Meanwhile, Katzman is excited about the results evolving over the last year that the plume edge has tightened and there are dramatic decreases in chromium concentration levels at a monitoring well along the Laboratory’s boundary with San Ildefonso . He said the project’s groundwater models appear to have predicted the response of the plume to the Interim Measure approach and he hopes to see the plume retract even more this summer.
“We’re still not below 50 ppb groundwater standard at monitoring well R-50 along the San Ildefonso boundary, but it’s well on its way. The model suggests it could take a year or two for that to get working over there but one of the awesome things about this work is you get to see real data and not just model results. Sometimes it’s faster and sometimes it’s slower than model predictions. But we take that information and fold it back into the model and constantly update, so it’s a great process,” he said. “Our goal is to get the plume edge back into a much smaller footprint within the Laboratory boundary.”