In May 2017, a 20-ft-by-20-ft section of the Hanford Nuclear Waste Site PUREX Tunnel 1 collapsed. It instantly became international news, although no radioactive waste was released. The collapse prompted an emergency project to fill the Plutonium Uranium Extraction Plant tunnel with grout and also placed a newfound focus on the 1964-built, 1,700-ft-long PUREX Tunnel 2.

This spotlight on Tunnel 2 prompted Hanford and Dept. of Energy officials to quickly move toward grouting that tunnel, even seeking approval from the Washington Dept. of Ecology’s Nuclear Waste Program, the state regulator overseeing Hanford cleanup, to begin work before public comment wrapped up.

That approval wasn’t granted.

Following two open comment meetings, one in Richland and the latest in Seattle in early September, the public still has until Sept. 27 to comment on the plan to fill the tunnel with grout as a way to stabilize the waste storage tunnel, even as reports surface that the tunnel has corrosion of bolts and weld plates.

The second tunnel, which holds 28 rail cars contaminated with high-level radioactive waste, is newer and longer than PUREX 1, but has shown deterioration that could lead to its collapse, according to DOE officials. The most recent investigation into the tunnel has heightened tunnel collapse to “anticipated” and the potential for severity to “moderate.”

“DOE is committed to the safety of its workforce, the public and the environment,” says Doug Shoop, manager of the DOE Richland operations office, in a statement. “Grouting safely and efficiently reduces near-term risk by providing interim stabilization while DOE and Ecology evaluate future closure options.”

Grouting was chosen for the first tunnel and then recommended for the second tunnel following an independent panel of experts, who evaluated options based on safety, ease, cost and the ability for future disposition of the equipment in the tunnels.

Local lawmakers and businesspeople have also asked state officials to allow an early start to the grouting process, ensuring work gets completed before the winter months and any potential danger thwarted.

While Ecology has denied the request to start work early, citing the public’s right to question grouting as the proper solution to the tunnel waste issue, it will allow DOE to set up equipment needed for the grouting process, reports the Tri-City Herald. The newspaper says nearly 5,000 truckloads of grout are needed to fill the tunnel and a mobile grout batch plant has already started to take shape at Hanford.

Further investigations into PUREX 2 during 2018 offered video evidence of corrosion inside the tunnel, leading DOE representatives to question how long the tunnel could take the wet winters in Eastern Washington. Also, unlike in the first tunnel collapse scenario, the fact that steel beams fill Purex 2 make a collapse more dangerous. As with the first tunnel collapse, the presence of 8 feet of soil atop the tunnel could serve to dampen any airborne spread of contaminants.

Follow Tim Newcomb on Twitter at @tdnewcomb.