The partially collapsed waste storage tunnel at the Department of Energy’s Hanford Site in Washington state should be additionally stabilized by the end of the year, cleanup contractor CH2M Hill Plateau Remediation Co. said Tuesday.
The company announced the award of a $2.8 million subcontract to Intermech Inc., of Richland, Wash., to fill PUREX Plant Tunnel 1 with grout. The grouting is expected to start next month and to wrap up by Dec. 31, according to a CH2M press release.
The 20-foot-long roof collapse was discovered on May 9 at the tunnel holding eight railcars loaded with radioactively contaminated equipment from the PUREX Plant, which recovered plutonium through chemical treatment of irradiated fuel rods during Hanford’s plutonium production days. Soil and sand has been poured into the hole to stabilize the tunnel, and a temporary cover has been placed over the structure.
The Energy Department and CH2M Hill in May selected grouting as a means for further stabilizing the tunnel. The process will involve placing an elevated platform above the collapsed section, then driving pipes through the sand and soil into open space beyond, the contractor said. Hoses will be used to pour roughly 6,000 cubic yards of grout into the tunnel.
The grout will help further help ensure no radioactive contaminants escape, according to the release. Subsequent stabilization activities and steps for permanent closure of the tunnel remain possible.
There was no update regarding planning for stabilizing the other PUREX waste storage tunnel, which in June was found to be at “high” risk of collapse, a CH2M Hill spokesman said Tuesday. On Aug. 1, DOE told the Washington state Department of Ecology that it wanted to convene a panel of experts to provide input on the means for stabilizing Tunnel 2. The state regulatory agency had demanded DOE submit a plan for stabilizing the tunnel by that date.
