Frank Munger, Knoxville News-Sentinel Staff
Knoxville News Sentinel
U.S. Department of Energy
December 18, 2011, OAK RIDGE, TN - Building 81-10 was constructed in 1943 as a tin shop to support the Manhattan Project work at Y-12.
In the 1950s, as the Cold War took hold, the relatively modest facility was converted to a salvage operation to help recover some of the mercury lost during the furious processing of materials for hydrogen bombs.
A 16-foot-high, gas-fired "roasting furnace" was the centerpiece of the recovery plant on Y-12's southwest side.
"Various materials contaminated with mercury, such as waste insulation, process sludge and dirt from mercury spills, were introduced into the top of the furnace and heated to a high temperature to vaporize the mercury and separate it from the solid materials," a Y-12 report said.
"Solid wastes were removed from the bottom. The furnace was equipped with a cooling coil to cool hot flue gases and condense and separate the mercury from the gas."
It's not clear how much mercury was rescued during the five years of salvage operations (1957-62), but Building 81-10 created an environmental legacy of its own with spills and emissions.
Y-12 spokeswoman Ellen Boatner said the facility was cleaned in 1971. In 1995, the building's structure, furnace and leftover containers were removed or demolished, leaving only the concrete foundation pad, she said. The basin surrounding Building 81-10 was remediated in 1998, Boatner said.
Despite these measures, the building's concrete pad and the surrounding soils are still significantly contaminated with an estimated 3,000 pounds of mercury.
The Environmental Protection Agency is pushing for the site to be excavated in the near term to remove the mercury source, but it's not clear whether it'll get priority with so many demands.
"They have enormous problems and just have so much money," said Patsy Goldberg, a program manager in the Superfund Division at EPA's regional office in Atlanta. "We acknowledge that it's going to be technically very difficult to get all that mercury out of there. But our mission, for us to do our job, you have to at least demonstrate that you have gone after the low-hanging fruit."
Excavating the 81-10 site would be an example of low-hanging fruit, Goldberg said.
If approved, the mercury cleanup at 81-10 could become a test run for much larger projects that lie ahead at Y-12 — such as demolition and cleanup of the huge buildings once used to process lithium and addressing the tons of mercury in and around them.
John Eschenberg, the U.S. Department of Energy's interim manager in Oak Ridge, said a "comprehensive characterization" of the 81-10 site is taking place and will help determine, along with the availability of funding, when and how to proceed with the 81-10 cleanup.
"We won't know until we get the results," Eschenberg said. "There are a lot of things to be learned."
The Oak Ridge Institute for Science and Education, a Department of Energy institute, studied the site in the summer of 2010. That work included taking about 30 core samples from the concrete pad and the surrounding ground.
"It was really just a reconnaissance sampling," said Sarah Roberts, director of the institute's Independent Environmental Assessment and Verification Program. Even the limited sampling effort cost about $544,000.
Roberts said samples taken from the site had mercury concentrations as high as 4,000 parts per million, based on lab analysis with a technique known as X-ray fluorescence. Tests identified mercury as deep as 30 feet. The highest levels were found in the top 8 feet of soil, she said.
A key finding, although tentative, was there didn't appear to be a "likely" pathway for the mercury contamination at the 81-10 area to reach East Fork Poplar Creek, which could move the mercury off site and into the community.
Goldberg said EPA believes there is potential for mercury to migrate to the creek.
The 2010 sampling effort had another purpose.
Some of the contaminated soil samples taken by the science institute and its subcontractor RSI were provided to scientists at Oak Ridge National Laboratory and Savannah River National Laboratory. Researchers are studying mercury in the environment and trying to better understand how different conditions cause mercury to change forms, including production of highly toxic methylmercury
RSI, a subcontractor for the Oak Ridge Institute for Science and Education, performs soil characterization work around Building 81-10 in July 2012 at the Y-12 Nuclear Security Complex. The building housed a roasting furnace in the 1950s that was used to recover mercury.