A hazardous chemical has turned up in more preliminary well water tests at the U.S. Department of Energy’s desert site, federal officials said Wednesday.
But those officials said high concentrations of tetrachloroethylene in two wells doesn’t mean the surrounding East Snake Plain Aquifer is contaminated with the clear chemical liquid. Known as PCE, it is often used for dry cleaning and as a metal degreaser.
The DOE, U.S. Geological Survey and cleanup contractor Fluor Idaho maintain the PCE is coming from inside the well shaft itself, which is sealed off from the surrounding aquifer with plastic piping.
DOE and Fluor said they plan to conduct further tests and put together a cleanup plan in the coming months. The U.S. Environmental Protection Agency and the Idaho Department of Environmental Quality are monitoring the effort.
The shafts of the Westbay-brand wells, nearly a quarter-mile deep, were filled with an outside water source when they were installed years ago, and that water has remained separate from the surrounding aquifer, officials said.
“At this point we’re pretty comfortable this isn’t a big (aquifer) contamination problem — it’s the well itself,” said Nolan Jensen, DOE environmental restoration manager. “Based on the way the well is constructed, there is essentially no risk of what we found in the well getting out of the well and into the aquifer. So we’re pretty comfortable this is a confined situation.”
Officials grew concerned when traces of PCE first showed up in routine tests of Well No. 2051 late last year. Dozens of similar monitoring wells are positioned around the DOE site, ensuring nuclear cleanup and research activities aren’t polluting the region’s most abundant water source. Officials were stumped on how this unusual chemical may have reached the aquifer, and why it had only been detected in a single well.
Later tests showed 824 micrograms of PCE per liter of water in the well, located not far from the Big Lost River Rest Area. The federal safe water drinking standard is 5 micrograms.
Last month, the USGS conducted routine tests on three more Westbay wells. Well 2050A, near the Advanced Test Reactor, showed 830 micrograms of PCE per liter, and the other two had trace amounts of PCE. They are near the Radioactive Waste Management Complex, south of U.S. Highway 26.
Seven more Westbay wells will still need to be tested.
Roy Bartholomay, a USGS hydrologist who leads the agency’s Idaho National Laboratory office, said it’s possible the outside water used to fill the wells was contaminated, and tests never picked up on it before. Water from the two wells that have so far shown high amounts of PCE came from the same source.
It may have also been caused by contaminated testing equipment being lowered into the wells, or piping seals inside the well degrading over time, officials said.
“They’re all just theories. Some are more probable. But … we didn’t expect this at all,” said Marc Jewett, director of environmental restoration for Fluor.
“Our ultimate goal is to try and figure out as best we can what happened, and see if there are improvements in the procedures and access to the well, that we can make more rigorous,” he said.
Luke Ramseth can be reached at 542-6763. Twitter: @lramseth