HANFORD, Wash. - Workers from the Hanford Department of Energy have finished stabilizing a waste storage tunnel with engineered grout after it partially collapsed earlier this year.
Since early October, crews worked mostly at night to place several thousand cubic yards of engineered grout into Tunnel 1 near the Plutonium Uranium Extraction (PUREX) Facility.
According to the Hanford Department of Energy, “grouting reduces the risk of further collapse and increases the protection for workers, the public and the environment from radiological hazards, while not precluding future remedial actions or final closure decisions.”
Department of Energy contractor CH2M HILL Plateau Remediation Company (CH2M) began grouting October 3 and placed the last truckload of grout on November 11, without any injuries.
“Stabilizing Tunnel 1 was achieved safely and quickly, due to our skilled workers, solid planning, and extensive coordination,” said Doug Shoop, manager, DOE Richland Operations Office. “Our contractor not only completed this work safely, but also ahead of the Department’s projected completion time-frame of late December.”
“The team did an amazing job,” said Ty Blackford, president and chief executive officer, CH2M HILL Plateau Remediation Company. “I couldn’t be more proud of the crew, and all those who supported planning and preparations.”
Approximately 521 truckloads (4,434 cubic yards) of grout were placed in the tunnel. Cameras in the tunnel ensured the grout flowed the length of the tunnel and around the contaminated equipment inside.
The grout was also injected in several lifts, or layers, and each lift was allowed to set up before the next began. Approximately one foot of space was left between the top most layer and the ceiling of the tunnel.
Now that Tunnel 1 is secure, we can focus on our evaluation and determining the appropriate course of action for stabilizing Tunnel 2,” Shoop said.
An integrity analysis completed earlier this year showed nearby Tunnel 2 does not meet current codes for structural integrity, and it may not be able to bear the weight of the soil above the tunnel.
Like Tunnel 1, Tunnel 2 contains railcars with contaminated pieces of plutonium processing equipment.
Enhanced surveillance is in place to detect any changes to the structural integrity of the 1960s-era waste tunnel.
Plans to stabilize Tunnel 2 are under evaluation and should be finalized in the coming weeks.