Cold War Landfill in Idaho Moves a Major Step Closer to Final Closure

U.S. Department of Energy Office of Environmental Management crews at the Idaho National Laboratory Site recently completed the single largest demolition project in Idaho Cleanup Project history, demolishing more than 520,000 square feet of building space three months ahead of schedule and under budget.

Decontamination and demolition (D&D) crews with cleanup contractor Idaho Environmental Coalition (IEC) removed the last of 10 steel-framed, soft-sided buildings - nine for waste exhumation and one for waste storage - constructed over a 97-acre Cold War-era landfill called the Subsurface Disposal Area.

The landfill accepted INL Site-generated radioactive and hazardous waste beginning in 1952, and waste from the former Rocky Flats Plant near Denver, Colorado, and other waste generator sites from 1954 to 1970. In 2008, the DOE, state of Idaho and U.S. Environmental Protection Agency agreed to exhume targeted radioactive and hazardous waste from the landfill. The waste from nine areas of the landfill covering a total of 5.69 acres included filters and molds, solidified sludge and a reactive uranium material called "roaster oxides."

The exhumation project was completed 18 months early. To date, more than 90% of the exhumed waste has been shipped out of Idaho for permanent disposal.

Following completion of waste exhumation at two of the enclosures, the buildings were repurposed for crews to reduce the size of waste boxes from Rocky Flats and large gloveboxes from the former Mound Site in Miamisburg, Ohio. Later, the enclosures were used to treat and repackage sludge waste originating from Rocky Flats. A third enclosure was used to condition the roaster oxides from Rocky Flats before workers at the facility began targeted waste exhumation.

Idaho Cleanup Project workers treat sludge waste at the Accelerated Retrieval Project V facility.

To prepare for the demolition of each enclosure, crews removed internal equipment and performed extensive decontamination activities on the highly contaminated structures to allow for safe demolition. They covered the exhumation footprint with clean soil and removed the facility ventilation system.

Final steps included applying fixatives, removing the exterior skin and weakening the support components of the buildings through an engineered approach. Large bulldozers pulled the skeletal frames over. Following the sizing of the metal structures with heavy equipment, the contaminated debris was buried, and clean cover material was placed over each former waste exhumation footprint.

Eventually an engineered cover containing native materials will be constructed over the entire landfill to ensure long term protection of the underlying Snake River Plain Aquifer.

A shipment of transuranic waste exhumed from the Subsurface Disposal Area at the Idaho National Laboratory Site is placed in TRUPACT containers and sent out of Idaho for permanent disposal.

"Removing these enclosures from the Subsurface Disposal Area puts us a step closer to closing the final chapter on the Subsurface Disposal Area landfill," EM Idaho Cleanup Project Manager Mark Brown said. "This was a combined effort by a very talented contractor workforce, with effective management by our cleanup contractor, IEC, and excellent oversight by my federal staff."

IEC President Dan Coyne was equally appreciative.

"The dedication of our workforce is exemplified every day in the risks we reduce to our communities and environment," he said. "Thank you all for completing this important work safely and be proud of what you have accomplished."

-Contributor: Erik Simpson