One of Hanford’s highest contamination risks to the Columbia River and groundwater is a thing of the past.
Hanford executives braved chilly temperatures Thursday morning to laud the complicated cleanup of the high-hazard waste site called the 618-10 Burial Ground, six miles north of Richland.
The 7.5-acre site, roughly one mile west of the Columbia Generating Station nuclear plant, contained some of the most hazardous waste on the Hanford reservation. Getting to this point took nearly eight years.
“Cleaning up the 618-10 burial ground was a massive undertaking,” said U.S. Sen. Maria Cantwell, D-Wash. “The Energy Department’s Richland Office has done an incredible job of decontaminating, demolishing, removing waste and remediating the river corridor.”
Sen. Patty Murray, D-Wash., and Rep. Dan Newhouse, R-Wash., joined Cantwell in commending the milestone and the Hanford workers involved.
They went on to urge federal officials, including Energy Secretary Rick Perry, to continue the work on a long list of cleanup projects on the Central Plateau that involves about 1,000 waste sites, 500 facilities and contaminated soil and groundwater, according to a joint statement.
Tammy Hobbes, vice president for the 618-10 project and the Environmental Restoration Disposal Facility for CH2M Hill Plateau Remediation Company, led a media tour Thursday to demonstrate the scope and progress of what officials called one of Hanford’s most vexing challenges.
The term “618-10” covers several related cleanups.
One, the 316-4 “crib,” contained two tanks and fill apparatus to hold liquid uranium-related waste associated with the now-demolished 321 Building. About 200,000 liters of waste were disposed of at the crib between 1948 and 1955.
The crib held two bottomless tanks buried about 10 feet below grade and resting on gravel. Workers removed the tanks and more than 200,000 cubic feet of soil in 2004 and 2005. Work was suspended in 2005 when it was discovered the contamination extended to the boundary of the nearby burial ground.
Last fall, workers resumed the project, removing 27,000 truckloads of dirt to create sloping 900-foot path to the relatively confined waste plume at the crib site. About 10 percent of the soil was contaminated and sent to the lined Environmental Remediation Disposal Facility, about 30 miles away. The excavation area was completely refilled this summer.
The larger 618-10 area served as a dump site for radioactive waste from laboratories and reactor fuel development facilities at the Hanford 300 area from 1954 to 1963. It included 94 waste-filled pipes, buried vertically to a depth of more than 20 feet, as well as direct dumping into an open trench.
Eighty of the vertical waste pipes were fashioned by welding the walls of 50-gallon drums end to end. The remaining 14 were made of steel.
CH2M Hill and its predecessor, Washington Closure Hanford, encapsulated the vertical waste pipes with “overcasings” to isolate them from the surrounding soil. Waste removal began in early 2016.
Processing the vertical pipes was one of the most thorny technical challenges at Hanford and involved piercing intact drums in contained rooms to determine their contents. Huge vats of sand hung overhead, available to smother any unexpected reactions.
The last were removed by June.
The direct dumping made the 618-10 burial ground an especially difficult cleanup. Old photos show where boxes, cans and other debris spilled down a slope, much the way modern garbage flows down hill at illegal dump sites.
The lax placement made the burial ground one of Hanford’s most challenging because officials simply did not know where and what to look for over the area.
In all, more than 500,000 tons of soil was removed to the storage facility for perpetual storage.
Officials loosely calculate the volume would fill six football fields to the depth of a 30-foot goal post.
Work will continue into 2019 as workers refill the massive trench with clean fill and perhaps 100 jersey barriers that were used to control traffic during the project. The refill is about one-third complete.
Once the hole is filled, the surface will be given a more natural contour. It will be re-vegetated with native plants in 2019.
“They are carrying out critical work, and in turn, the federal government must always fulfill its obligation to ensure workers and the entire Tri-Cities community have the resources they need to continue cleanup in a safe, efficient manner that leads to everyone’s ultimate goal of this land being restored to its natural state,” Murray said in a statement.
A network of monitoring wells in the area tested negative for migrating waste, suggesting the materials dumped in the 618-10 area did not reach the Columbia River. However, the proximity to the waterway made the cleanup a priority.
Hobbes called the 618-10 project one of the most intense efforts she’s been involved with in three decades in the industry. At the peak of the project, the relatively small area was the intense focus of work by nearly 200 workers and three dozen pieces of heavy equipment.
The near perfect safety record is one of the major byproducts of the effort.
“Nobody got hurt on this job and nobody got contaminated,” she said.
The final piece of the 618-10 project is the 600-63 waste site, where an underground monitoring station was installed in 1978. The site was excavated in an eight-day project this summer.
Earlier this year, they urged the Trump administration to provide strong funding to reduce risks and the long-term costs at Hanford, to meet Tri-Party Agreement milestones and to protect the Tri-Cities, as it puts together its annual budget requests.
Reporter Annette Cary contributed to this report.