The Oak Ridge Office of Environmental Management (OREM) and contractor UCOR (United Cleanup Oak Ridge) are now focusing on soil and groundwater remediation at the East Tennessee Technology Park (ETTP), according to the US Department of Energy’s (DOE’s) Office of Environmental Management (EM). This is the final stage in a clean-up programme that has dismantled more than 500 ageing, contaminated structures.

For 40 years, the 2,200-acre ETTP hosted a complex of facilities that enriched uranium. Its origins lie in the World War II Manhattan Project to develop nuclear weapons and it operated until 1985. In addition to defence activities , the plant also produced enriched uranium for the commercial nuclear power industry. In 1987, DOE terminated uranium enrichment operations in Oak Ridge and closed the site permanently.

This left ETTP with contaminated buildings, soil, sediment, and groundwater that required remediation to protect human health and the environment. In 1989, DOE formed EM to begin the clean-up in order to transform the site from a shuttered, government-owned former enrichment complex into a privately-owned, multi-use industrial park. In 2020, EM completed the core clean-up at the site – which included dismantling buildings and addressing major areas of soil contamination.

With crews set to finish excavating and removing contaminated soil from the site next year, the focus is now turning to groundwater.

“We’ve made great strides in reducing risks and restoring the environment at ETTP,” said OREM Regulatory Specialist Roger Petrie. “As we near completion on the remaining soil clean-up projects, groundwater remediation is the final effort to achieve our mission at the site.”

ETTP is divided into three sections for groundwater remediation planning. One section is the Main Plant Area, which encompasses most of the operations area of the former enrichment complex. Another section is the area where the large K-31 and K-33 uranium enrichment buildings once stood. The third section, Zone 1, is the area immediately surrounding the Main Plant and the K-31 and K-33 areas. The US Environmental Protection Agency and Tennessee Department of Environment & Conservation recently approved OREM’s proposed plans for addressing groundwater in the Main Plant and K-31 and K-33 areas.

The preferred approach for groundwater remediation in the Main Plant Area is enhanced in situ bioremediation. This widely used technology for treating contaminated waste involves injecting microorganisms and a carbon source, such as vegetable oil, into the ground. The microorganisms then reduce or detoxify the contaminants.

“Because site conditions differ, no single remediation technology is applicable for all areas at ETTP,” said Kevin Ironside, UCOR Environmental Programs & Planning Manager. “A different approach is being recommended for the K-31 and K-33 area as the most effective means for addressing groundwater remediation.”

For the K-31 and K-33 Area, OREM is proposing to use monitored natural attenuation and land use controls. Monitored natural attenuation relies on natural processes that reduce contaminant concentrations in groundwater. This involves monitoring groundwater conditions with land use controls limiting potential exposures. The proposed remedies for Zone 1 will be announced later.

Over the past two decades, OREM has transformed the former uranium enrichment complex into a multi-use industrial centre, national park and conservation area. ETTP is now home to 25 businesses with more expected in the years ahead. It also hosts the Manhattan Project National Historical Park, and has a 3,000-acre conservation area for public use.

The remaining soil and groundwater remediation required at the site is expected to continue until 2024. EM’s goals for ETTP are to:

  • Address remaining soil and groundwater contamination;
  • Complete remaining land transfers from government ownership for future beneficial reuse;
  • Complete construction on remaining historic preservation facilities; and
  • Transfer long-term stewardship areas to DOE’s Office of Legacy Management.

Image: Employees take groundwater samples at the East Tennessee Technology Park to understand which areas require further action. The site is divided into three sections for groundwater remediation planning – the Main Plant Area, K-31 and K-33 Area and Zone 1