EM has rehabilitated a deep aquifer monitoring well at DOE’s Idaho National Laboratory Site and will return it to service.
Office of Environmental Management
January 22, 2019
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IDAHO FALLS, Idaho – EM has rehabilitated a deep aquifer monitoring well at DOE’s Idaho National Laboratory Site and will return it to service after it tested positive for an industrial solvent three years ago.
Known as Middle-2051, the well is located in the south-central portion of the 890-square-mile site. It first tested positive for perchloroethylene (PCE) in November 2015. Because the 1,110-foot-deep well is sealed off from the surrounding aquifer, scientists with EM cleanup contractor Fluor Idaho were able to determine that the solvent originated in the well’s tubing fluid and was not present in the groundwater.
In an ensuing investigation, researchers determined two similar wells in different areas of the site also contained PCE in their tubing fluid. Engineers found that only the tubing fluid isolated within the wells was contaminated. Investigators deduced an isolated event likely led to the contamination of the wells.
Fluor Idaho’s Environmental Restoration (ER) Program developed an innovative, custom-made device called a “filter-swab” to capture the PCE contamination in the tubing fluid. The device is a stainless steel, screened sleeve filled with granulated activated carbon. Workers lowered the device more than 1,000 feet into the wells, and the PCE attached to the carbon as the water passed through the sleeve.
With each pass in the well column, PCE concentrations were reduced,” Fluor Idaho ER Program Director Mark Jewett said. “Tubing fluid samples that were analyzed by an independent lab showed that PCE levels in Middle-2051 were reduced to such a level that we can return the well to service and begin collecting aquifer samples in the immediate future.”
Rehabilitation of the other two wells using the same technology is scheduled for completion by this summer.
“We’re very encouraged by what we’ve observed thus far,” Jewett said. “If all goes well, we should be able to use these additional two wells for aquifer sampling once again.”
The wells are important for understanding how deep site-generated contaminants are located within the aquifer and the speed at which they move in water.