PADUCAH, Ky. – A new environmental remediation project at EM’s Paducah Site will deploy a biological technology to eliminate underground contaminants that compromise the area’s groundwater. The bioremediation process uses deliberately introduced microorganisms to break down environmental pollutants.
For years, EM and its remediation contractors have used a variety of technologies to successfully reduce offsite migration of such contaminants from the Paducah Site. An increasingly significant part of EM’s strategy targets onsite sources that accumulated over decades.
In the 1990s, an area of subsurface soil contamination was discovered near the site’s C-720 Machine Shop. C-720 supported operation of the gaseous diffusion plant where DOE and later industrial tenants enriched uranium to support national security and commercial energy applications. The machine shop was used for fabrication, assembly, cleaning and repairing equipment.
Soils in the area, spanning about a quarter-acre northeast of the C-720 Building near the Southwest Groundwater Plume, are contaminated with tricholoroethene (TCE). The TCE likely resulted from routine equipment-cleaning and rinsing with solvents at the machine shop. Historically, TCE was a common industrial degreaser.
EM evaluated several options for removing TCE from groundwater at this location and identified bioremediation to be an effective treatment technology based on the properties and characteristics of the soil and its contaminant.
“After many successful years of mitigating technologies reducing migration of offsite groundwater contamination, we will target TCE source reduction at the Paducah Site,” said Portsmouth/Paducah Project Office Manager Joel Bradburne. “We believe bioremediation will advance our mission to decrease source contamination and prepare the site for final cleanup actions.”
The bioremediation process uses high-pressure water to create horizontal openings, or zones, in the underground. Then 443,000 pounds of a specialized type of iron metal, commonly used in environmental remediation, and 220,000 pounds of sand will be injected into those openings, which allows workers to inject 130,000 gallons of emulsified vegetable oil and 57 gallons of a commercially available TCE-reducing bacteria into the zones. The vegetable oil provides nourishment for bacteria and generates subsurface conditions to degrade the TCE. Groundwater monitoring wells will be used to monitor the progress over several years.
EM’s deactivation and remediation contractor, Four Rivers Nuclear Partnership (FRNP), recently began drilling, sampling and other activities to lay the groundwork for bioremediation to begin.
“Bioremediation combined with natural degradation should cause the contamination to naturally decrease over the next several years,” FRNP Program Manager Myrna Redfield said. “These efforts are critical steps in the success of Paducah’s ongoing cleanup efforts to reduce groundwater contamination.”
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