INL Site Tested Retrieval Technologies Prior to Joining National Priorities List

IDAHO FALLS, Idaho – Following several buried waste exhumation projects in the 1970s, the DOE Idaho National Laboratory (INL) Site tested technologies to allow for a larger waste retrieval effort and attempt to minimize the spread of contaminated soil.

In the late 1980s, engineers were developing a plan to demonstrate the use of vitrification for specific buried waste pits. Using high-electricity probes throughout a pit could conceivably melt the waste and surrounding soil together into a mass. Later, they tested various plastic resins to inject into a simulated waste pit using a high-pressure drill rig. Once hardened, the mass could be broken into manageable and retrievable pieces.

Also during that time, remediation contractors, working with INL Site engineers, proposed a demonstration project at one of the landfill pits using their proprietary retrieval and treatment processes. Pit 9 was selected because it was one of the last buried waste pits, in use until 1969.

In the 1990s, engineers experimented with cryogenics — a science that addresses the production and effects of low temperatures. A simulated waste pit, complete with empty barrels and boxes, was created within a portable tent. Liquid nitrogen was injected into the simulated waste pit to freeze the contents and surrounding soil. Heavy equipment was used to break up the mass.

Although these retrieval technologies showed some promise, they were abandoned due to technical challenges. Later however, certain sections of the landfill, called the Subsurface Disposal Area, were injected with paraffin wax to encapsulate specific waste types, preventing the release of contaminants into the surrounding soil.

In 1989, cleanup of the buried waste took a different turn after the INL Site was added to the Environmental Protection Agency’s (EPA) National Priorities List of Superfund Sites due to suspected and confirmed releases of radioactive and hazardous waste into the underlying Snake River Plain Aquifer.

Now a Superfund site, the INL Site entered into a tri-party agreement between the DOE, state of Idaho and EPA. In the next two years, the agencies compiled a list of suspected and confirmed waste release sites, assigned the sites the Superfund designation of waste area group (WAG) or operable unit (OU), and developed a schedule for investigation and cleanup if necessary.

In 1991, the agencies signed the Federal Facility Agreement and Consent Order and associated action plan. The buried waste site received its own waste area group — WAG 7 — and operable unit — OU 7-13/-14 — designations.