Fluor Idaho officials will test 11 groundwater monitoring wells on the Idaho National Laboratory site this spring following the detection of the hazardous chemical tetrachloroethylene, or PCE, inside two of the wells last year.
The PCE surprised state and federal officials when it showed up in concentrations well above safe drinking water levels during a routine test of one well in late 2015. It appeared in follow-up tests of the same well last summer, and another well of the same design also tested positive at levels well above drinking water standards. The colorless liquid is often used for dry cleaning, metal degreasing, and paint stripping.
Last month, the Environmental Protection Agency and Idaho Department of Environmental Quality approved a Fluor field sampling plan to test or re-test all 11 wells officials suspect might contain the chemical, a process that can start once the snow melts, said Marc Jewett, Fluor’s director of environmental restoration.
Officials believe the contamination is limited to water located inside the plastic well shafts, which are nearly a quarter-mile deep. The shafts are sealed off from the surrounding Snake River Plain Aquifer, except for several “ports” where the aquifer water samples are taken. The 11 wells are all of the same design and brand, known as Westbay. They are part of a system of about 150 wells positioned around the lab’s 890-square-mile desert site, used to monitor aquifer contamination from nuclear research and cleanup.
The water inside the wells came from an outside source when the wells were built more than 10 years ago. Officials remain unsure how the PCE might have entered the wells, but hope additional sampling will help solve the mystery. They also plan to send a camera to the bottom of each well to see if they can find any hints. In addition, officials this winter studied previous sampling and construction records from the wells, to see if there are any hints about how they might have become contaminated, said Jeff Forbes, a Fluor hydrogeologist.
After the field sampling plan is complete, Fluor will develop a cleanup plan for the contaminated wells. It is not yet known how the cleanup process will work, or how much it will cost.
