The Los Angeles Times is estimating that an explosion that occurred at a New Mexico nuclear waste dumping facility in 2014 could cost upwards of $2 billion to clean up.

Construction began on the Waste Isolation Pilot Plant (WIPP) in New Mexico's Carlsbad desert in the 1980s (PDF). The site was built to handle transuranic waste from the US' nuclear weapons program. The WIPP had been eyed to receive nuclear waste from commercial power-generating plants as well.

According to the LA Times, the 2014 explosion at the WIPP was downplayed by the federal government, with the Department of Energy (DoE) putting out statements indicating that cleanup was progressing quickly. Indeed, a 2015 Recovery Plan insisted that "limited waste disposal operations" would resume in the first quarter of 2016. Instead, two years have passed since the incident without any indication that smaller nuclear waste cleanup programs around the US will be able to deliver their waste to the New Mexico facility any time soon.

The 2014 explosion apparently occurred when engineers at the Los Alamos National Laboratory were preparing a drum of plutonium and americium waste—usually packed with kitty litter (yes, kitty litter)—and decided to "substitute an organic material for a mineral one."

"The new material caused a complex chemical reaction that blew the lid off a drum, sending mounds of white, radioactive foam into the air and contaminating 35 percent of the underground area," the LA Times wrote. The dump's filtration system, which was supposed to "prevent any radioactive releases," subsequently failed.

No workers were in the shafts of the dump at the time. Workers on the surface were only exposed to low doses of radiation due to the HEPA filters in the ventilation system.

Still, the dump site was set to receive another 277,000 drums of radioactive waste from around the country. The congestion is now creating a costly problem.

The federal government renewed its contract with dump operator Nuclear Waste Partnership to the tune of $640 million extra for cleanup. That number could grow, especially as federal officials now say the contaminated ventilation system on the dump needs to be replaced—a project that will not be completed until 2021. Until then, the dump must remain open, but it can not accept nuclear waste at the rate it had planned. The dump costs $200 million a year to remain open, the LA Times reported. Meanwhile, feds also have to pay to house the nuclear waste being stored at sites around the US (in Washington state and Idaho, for example) that's supposed to be on its way to the WIPP.

While there may be cheaper solutions to the problem, the Department of Energy is under pressure to fix the New Mexico dump to make good on a US agreement with Russia to fulfill mutual reductions of plutonium. WIPP is currently the primary destination for weapons-grade nuclear waste. If it closes, a likely expensive and time-consuming disposal alternative would have to be proposed.

Edwin Lyman, a physicist and nuclear expert at the Union of Concerned Scientists, told the LA Times that, "The decision means operations at the dump must resume. They have no choice."

That means that WIPP cleanup, including indefinite housing costs for nuclear waste around the country that was to be shipped to WIPP, could rank among the costliest nuclear waste cleanup efforts in US history, on par with clean up after Pennsylvania’s Three Mile Island disaster in 1979. Cleanup after that incident cost the federal government about $1 billion, or $1.7 billion adjusted for inflation.

Update: A DoE spokesperson e-mailed Ars on Wednesday, writing "The Waste Isolation Pilot Plant (WIPP) is critical to the Department of Energy’s mission to cleanup waste Cold War nuclear weapons production. WIPP is the nation’s only repository for the disposal of nuclear waste known as transuranic (TRU) waste, which consists of contaminated items such as clothing, tools, rags, residues, debris, soil, etc. The Department is committed to the recovery, and resumption of TRU disposal operations at WIPP when it is safe to do so.”

Correction: This article incorrectly stated that the LA Times said WIPP costs $500 million a year to keep open. The correct number is $200 million a year.