CARLSBAD, N.M. (KRQE) – Another seven-room section carved out of the underground salt deposits near Carlsbad, New Mexico is now full of transuranic waste. Soon, the salt will encase the waste, and workers will start filling up the next seven-room section.

The Waste Isolation Pilot Plant (WIPP) is the country’s final resting place for transuranic waste. That’s the leftover tools, rags, sludge and other materials contaminated with radioactive elements that have more protons (a higher atomic number) than uranium.

These waste products come from the country’s nuclear defense program, which has been producing waste since the 1940s. The facility near Carlsbad is currently the country’s only repository for such waste.

“Filling Panel 7 [which includes seven rooms] allows us to continue our important national mission of disposing of transuranic waste,” Reinhard Knerr, the U.S. Department of Energy Environmental Management Carlsbad field office manager, said in a press release. The program ensures the safety of those living near the waste, Knerr added.

To excavate the underground space, workers had to mine out nearly 160,000 tons of salt, according to the Department of Energy (DOE). In its place, they’ve stacked 20,056 containers of waste. There are close to 13,000 55-gallon drums in the section alone.

After filling the space, workers put in place a metal bulkhead, sealing off the area. Then, over time, the surrounding salt will shift and settle, sealing in the waste.

Now, it’s on to the next section of storage, called “Panel 8.” When the waste isolation plant was originally designed, Panel 8 was to be the final section of storage. But since then, two additional sections have been planned.