A heavy plastic cover was installed Saturday over the partially collapsed PUREX plant waste tunnel at the Energy Department’s Hanford Site in Washington state.
Work is expected to continue through Monday to secure the cover’s sides with 150 concrete ecology blocks and to crisscross cable lacings from the blocks across the top of the soil berm over the tunnel.
The breach in the top of the underground tunnel was discovered May 9 and by midnight the next day had been filled with 53 truckloads of sand and soil. The heavy plastic cover added by cleanup contractor CH2M Hill Plateau Remediation Co. as the next interim protective measure has a high-density polyethylene woven core and is resistant to puncture, abrasion, chemicals, ultraviolet rays, and oxidation, according to DOE. The 40,000-square-foot cover is intended to keep water from soaking into the soil topping the tunnel, adding to the weight on its timber roof.
DOE, CH2M, and the state Department of Ecology are expected this week to discuss additional actions to ensure the safe storage of contaminated equipment in the tunnel until they determine how to permanently dispose of the waste. The state has indicated the tunnel could be filled with a cement-like grout.
Contamination and radiation surveys, along with air sampling, have detected no elevated readings or activity above background levels, according to DOE. The agency has posted data collected since May 9 by both DOE and the Washington State Department of Health at the Hanford website.
On Thursday, Washington Gov. Jay Inslee and Oregon Gov. Kate Brown sent a letter to President Donald Trump and officials in his administration using the partial tunnel collapse to illustrate the need for adequate cleanup funding at Hanford. The administration is expected to issue its fiscal 2018 federal budget plan on Tuesday.
“The May 9th incident should serve as an urgent reminder of the challenges in cleaning up the Hanford site that require a rededication of attention and resources,” the letter says. Other budget priorities at the site should be the Waste Treatment Plant facilities needed to start treating low-activity radioactive waste, the highly contaminated soil beneath the 324 building, completion of Columbia River corridor cleanup, and continued treatment of contaminated groundwater, the governors said.
