Interim containment measures are underway on the eastern boundary of the chromium plume at the Los Alamos National Laboratory in New Mexico, U.S. Department of Energy Environmental Management Los Alamos Field Office (EM-LA) Manager Doug Hintze recently told the Regional Coalition of LANL Communities board.
In his Nov. 15 briefing to the board, Hintze highlighted the accomplishments of Newport News Nuclear BWXT-Los Alamos (N3B) since it took over as the legacy waste cleanup contractor at the lab 18 months ago. He also gave a picture of LANL’s overall environmental remediation program.
On the latter, Hintze said there were originally 2,100 legacy sites identified for remediation. That number is now down to 950. These sites range from small spills with only several cubic feet of contaminated soil to large landfills encompassing several acres. The original 2,100 sites were divided into 17 campaigns that are being worked on simultaneously, according to Hintze.
He told the board that EM-LA officials meet each year around July with representatives from the New Mexico Environment Department, the state regulator for cleanup at the lab, to discuss the scope of upcoming work and develop milestones based on available funding.
The president’s annual budget for LANL legacy waste operations has been about $195 million in recent years, Hintze noted. Congress has appropriated $220 million in fiscal 2019. It has yet to complete a full-year budget for fiscal 2020, which began on Oct. 1.
From 1956 to 1972, workers at a non-nuclear power plant at LANL periodically flushed chromium-contaminated water from the cooling towers into Sandia Canyon. At the time, chromium was commonly used as a corrosion inhibitor. The water flowed down Sandia Canyon as surface water, penetrated the underlying rock layers, and in time seeped into the regional aquifer beneath Sandia and Mortandad canyons. The lab ceased releasing chromium-contaminated water in 1972.
The plume, at concentrations above the state standard of 50 parts per billion (ppb), is approximately 1 mile long, a half-mile wide, and about 50 to 75 feet thick. The Interim Measure began in fiscal 2018: a combination of extraction, treatment, and injection to control plume migration and hold it within the lab boundary.
While the Interim Measure continues, DOE and N3B are evaluating potential technologies to remediate the plume, including the introduction of materials that would convert the chromium in place into a non- mobile and safe form. The final remedy will be proposed by DOE and is subject to public participation and approval by NMED.
Stabilizing the plume to ensure it does not migrate off lab property is EM-LA’s No. 1 priority, according to Hintze. He said the most important monitoring well is just north of the Pueblo of San Ildefonso.
The Interim Measure began on that southern boundary to make sure the plume could be arrested. The Interim Measure started on the southern boundary and is now operational on the eastern boundary. With the start of the Interim Measure on the eastern boundary, the program is fully operational.
“In FY 2019, 57 million gallons of chromium-contaminated water were treated and there was a significant decrease in chromium levels near that boundary,” Hintze said. “The latest results show 45 pp. The Interim Measure will continue as the final remedy is developed.”
Hintze said “pump and treat” is not the answer, but it could be part of the final remedy, which will be determined over the next couple years. It is designed to stabilize the plume to 50 ppb and to stop its migration.
“The chromium is not coming down in a big shower. It’s actually coming down in three fingers. That allows us to say that when we want to hit the greatest concentration that’s where we want to hit it from,” he said.
The motion of the plume is from the northwest to the southeast in the regional aquifer, and EM-LA hopes to stabilize it on the southern and eastern edges so it then can focus on concentration levels.
“The last thing you want to do is come up with a remedy that’s worse for the environment than what’s there. Stabilization is where we’re at,” he said.
Hintze also addressed the lab’s Technical Area 21, the Manhattan Project and Cold War-era complex of buildings that housed the lab’s plutonium processing facility, and home to groundbreaking tritium research for energy, environment, and weapons defense research.
At the height of operations, TA-21 contained 125 buildings, located off DP Road in Los Alamos. More than 1,400 cubic meters of what was mostly rubble from concrete slabs was shipped to Pit 38 in Area G for disposal, Hintze said. The TA-21 land will be turned over to DOE’s semiautonomous National Nuclear Security Administration following cleanup and eventually be transferred to Los Alamos County.
Most of the buildings have been torn down, but slabs and pipes remain to be taken out. EM-LA still has to figure out what to do with two Material Disposal Areas where radioactive waste was placed in TA-21.
Among other accomplishments, Hintze noted 16 shipments of legacy transuranic waste in fiscal 2019 to the Waste Isolation Pilot Plant near Carlsbad, N.M.; initiation of two nuclear waste remediation process lines; and remediation of 200 legacy waste containers. He said more than 1,500 cubic meters of mixed low-level and hazardous wastes were shipped to a commercial facility in Utah and commercial facilities elsewhere.
Hintze said EM-LA has 17 Consent Order milestones. The Compliance Order on Consent, commonly called the Consent Order, is an enforceable agreement between the New Mexico Environment Department and DOE for the cleanup of legacy waste at LANL. While EM-LA and its contractor conduct thousands of cleanup activities each year, those 17 Consent Order milestones are considered particularly important, Hintze said.
The public meeting on the fiscal 2020 Consent Order milestones is slated for 5L30 p.m. Monday in the Los Alamos County Council Chambers at the Los Alamos Municipal Building, 1000 Central Ave. in Los Alamos.
