By John Stang
The U.S. Environmental Protection Agency on Feb. 8 directed the potentially responsible parties for environmental remediation of the West Lake Landfill in Missouri to study potential groundwater contamination at the site.
The potentially responsible parties are Bridgeton Landfill LLC, Cotter. Corp. LLC, and the U.S. Department of Energy. Under a decision handed down by the EPA last September, they are already on the hook for cleanup of radiologically contaminated Operable Unit 1 (OU-1) of the Superfund site.
The latest directive involves Operable Unit 3 (OU-3), the designation for groundwater throughout the 200-acre former solide-waste disposal facility.
“While currently, the closest known drinking water wells to the site have shown no radionuclide detections above applicable drinking water standards, the OU-3 investigation will evaluate both current and potential future groundwater impacts as part of this comprehensive study,” EPA Region 7 Administrator Jim Gulliford said in a prepared statement. “This work will complement the work associated with implementation of the recently selected amended remedy for OU-1.”
Two contaminated zones at West Lake hold 8,700 tons of leached barium sulfate dating to the Manhattan Project, which were mixed with 39,000 tons of soil for use in 1973 as cover for trash at the landfill. Local concerns about the radioactive contamination were exacerbated by an underground fire that has smoldered since at least 2010 at the adjoining Bridgeton Landfill, which is also part of the full Superfund site.
The EPA has ordered the potentially responsible parties to analyze the “nature and extent” of groundwater contamination, according to an agency press release.
The entities are required to submit a work plan and a sampling and analysis plan within 120 days of the effective date of an administrative settlement agreement and order on consent between the EPA and the parties. Information on when the 120-day clock began was not available late this week.
The EPA will use the findings to determine if cleanup steps are required to ensure the protection and viability of groundwater within and outside of West Lake. “If sampling results during the OU-3 RI/FS indicate that action under Superfund law is appropriate, it will be addressed by a future OU-3 Record of Decision,” the agency said.
West Lake’s groundwater was found to have levels of radioactive uranium, radium, and thorium-230 during tests from 2012 to 2014. The majority of the radioactive material was thorium-230, which is a decay product of uranium, which was processed at the Mallinckrodt Chemical Works facility in St. Louis during World War II.
In September, acting EPA Administrator Andrew Wheeler signed off on an updated record of decision for remediation of OU-1, abandoning the 2008 agency directive to place an engineered cover over the radiologically impacted areas, along with digging monitoring wells.
The new approach calls for removing radiologically impacted material greater than 52.9 picocuries per gram down to a depth of 12 feet in most cases. In some cases, excavations could go as deep as 20 feet or as shallow as 8 feet. The EPA predicts the project will take three years to accomplish after on-site work begins. An engineered cover will be placed over the landfill once excavation is complete.
It will be up to the parties to divide up the estimated $205 million cost and hire contractors to tackle the work.
The first step of the project is remedial design, which was expected to take about 18 months. The state of that work was not immediately available.
Bridgeton LLC is a subsidiary of site owner Republic Services. The subsidiary in late 2018 sued Mallinckrodt LLC and EverZinc USA to recoup some of its costs for remediation at West Lake.
The then-Mallinckrodt Chemical Works processed uranium in St. Louis from 1942 to 1957, generating residues and other waste that were eventually transported to the West Lake Landfill. Some of that waste was produced by refining uranium ore and ore concentrates as part of the World War II Manhattan Project that were delivered by African Metals Corp., an EverZinc predecessor.
