The U.S. Department of Energy rolled out several options at a public meeting Thursday night to stabilize what’s known as Tunnel 2 at the Hanford nuclear reservation in southeast Washington. Stabilizing the tunnel became a priority after nearby Tunnel 1 was found partially collapsed this spring.

Tunnel 2 is filled with highly-radioactive equipment leftover from a plutonium plant and the feds say it’s also in danger of collapse.

At the meeting, they presented a raft of ideas to stabilize it:

  • Tarp it like they did to Tunnel 1
  • Slap a tent on it
  • Put a structure like a hangar over it
  • Put a more substantial building on it
  • Fill the tunnel with expanding foam
  • Cause a controlled collapse of the tunnel
  • Retrieve the waste from the tunnel
  • Fill it up with grout, like they plan with Tunnel 1
  • Simply watch the tunnel more closely than before

With each option, the Department of Energy is weighing how it protects the environment and people, how much it costs, and how easy it is to do, and maintain.

Several people after the meeting said they were worried that if Energy fills up both tunnels with grout, they may never clean up the tunnels further, essentially creating a shallow dump site of highly radioactive waste.

The feds say they’ll have the best option selected by August 1, and that they will take public comment before they select a final option.

Both Tunnel 1 and Tunnel 2 are part of what’s known as the PUREX plant. The factory extracted plutonium through complex chemical processes out of irradiated uranium rods. What’s left in the tunnels are large pieces of plant equipment that are highly contaminated and dangerous to humans. The tunnels used a remote locomotive and water-filled doors to protect workers when they were in use. No one has entered the tunnels for decades, and much is unknown about the waste inside and the conditions.

Tunnel 1 was found partially collapsed this spring by Hanford workers. Since the emergency Hanford leaders and site watchdogs have called for more money to be spent on Hanford’s aging buildings and infrastructure, saying cleanup isn’t going fast enough compared to the aging site. Hanford was the nation’s workhorse during World War II and the Cold War, pumping out large amounts of plutonium for bombs. What’s left is waste and infrastructure like the tunnels that still need cleaning up.