As reported by the Tri-City Herald.

As the mayors of Kennewick, Pasco, Richland, and West Richland urged the State of Washington to approve the U.S. Department of Energy's request to grout the tunnel containing highly radioactively contaminated equipment, in a bid to prevent its potentially "catastrophic" collapse, the state's Department of Ecology pushed back.

“What DOE is asking is to take irreversible action — put grout in that tunnel — before the the public process really has a chance to get off the ground,” said Alex Smith, [the State of Washington's Department of] Ecology’s Nuclear Waste Program manager.

The May 2017 collapse of a sister radioactive waste storage tunnel at the Hanford Nuclear Reservation risked a significant release of radioactivity into the outside environment, to blow downwind. In that emergency situation, DOE simply bulldozed dirt into the gaping maw of the tunnel's collapsed roof, exposed as it was to the open air.

Such ad hoc action could make future retrieval of the radioactive wastes difficult to impossible, as could grouting the second tunnel as DOE and the Tri-City mayors are urging now. This could mean locking the radioactive wastes in place, only to make inevitable their erosion into the environment (soil, groundwater, air) if the tunnels are simply abandoned as is, and as the soil cap and grout fail over long enough periods of time.