Kenneth Fletcher
WC Monitor
4/18/2014
After technetium from the K-25 demolition ended up in an Oak Ridge city wastewater treatment plant, the Department of Energy is making progress in shipping contaminated sewer sludge to the Perma-Fix Northwest Richland facility for processing. Cleanup contractor URS-CH2M Oak Ridge, LLC, wrapped up recently the high-profile effort at the enormous former gaseous diffusion plant, tackling last the technetium-contaminated portion and completing debris removal last month. However, in February elevated levels of technetium were found in sludge at a sewage treatment plant owned by the city of Oak Ridge. The levels have stayed below regulatory limits and have recently gone down to near normal levels. DOE has so far shipped 5,000 gallons of sludge to Richland and expects to undertake 20 more shipments of 4,000 to 5,000 gallons each at a total cost of $1.4 million.
Before beginning K-25 demolition DOE had assumed that a small amount of technetium may be carried into the groundwater from the contaminated debris , but it was not expected that the contamination would enter the site’s underground sewer pipes. “The sanitary sewage lines had been relined and renovated some time ago, so we expected that infiltration to be minimal, but measurements indicate some elevated infiltration. That’s why we’ve taken additional measures, which include completely plugging the sanitary sewer line,” Dave Adler of DOE Oak Ridge Regulatory Affairs told WC Monitor this week.
Releases Stayed Below Regulatory Limits
The state of Tennessee limits releases to 60,000 picocuries per liter on average, and DOE limits are in the same range, Adler said. Releases of technetium at K-25 have never exceeded the limit, he said, and due to measures implemented since then they have gone down further and now stand at about 9,000 picocuries. “Now the values being measured downstream from the lines are approaching normal levels again,” Adler said. “There is no concern that it will make it into water supply or waterways at levels exceeding accepted criteria.”
DOE notified the Tennessee Department of Environment and Conservation in February of the elevated levels of technetium-99. It has also been detected in surface water samples collected in Poplar Creek, which feeds into the Clinch River, TDEC spokeswoman Kelly Brockman said. “TDEC has collected some samples as part of our oversight of DOE and we will continue to do so. All required monitoring and subsequent clean-up is the responsibility of the Department of Energy as the responsible party under [the Comprehensive Environmental Response, Compensation and Liability Act]. TDEC and [the Environmental Protection Agency], as parties to the Federal Facility Agreement will work with DOE to plan and coordinate any response action that is needed,” Brockman said in a written response.
Cost Estimated at $1.4 Million
The Department said that the total estimated cost of $1.4 million for processing of the sludge at the Perma-Fix facility is the most efficient option. After undergoing thermal treatment in the plant’s bulk processing unit it will subsequently be disposed of at either EnergySolutions’ disposal facility at Clive, Utah, or at DOE’s Nevada National Security Site. “We could have treated the sludge at the wastewater treatment plant. We could have gotten it from the treatment plant and taken it back to the [East Tennessee Technology Park] and treated it there. We evaluated those options and the one that made the most sense was to get it and ship it for disposal,” DOE Oak Ridge spokesman Mike Koentop said. In order to be disposed of at the Oak Ridge onsite facility the sludge would have had to go through a “fairly elaborate” process to extract the excess water, Adler said. “This was a quick and affordable means of managing the sludge and keeping the city’s sanitary sewage treatment system operational,” he said.
There are some “lessons learned” from the experience that could be applied K-27, to the next major demolition project at Oak Ridge to continue to drive any releases to levels as low as possible below the permitted values. “We have identified some cost effective measures that could be taken to drive levels lower,” Adler said. “We will probably isolate the sewer lines right up front.”
‘This Isn’t a Result of Something That UCOR Did Wrong’
DOE officials said that the release of technetium into the sewage system was not due to an error on UCOR’s part. “This isn’t a result of something that UCOR did wrong,” Koentop said, emphasizing that the project is considered a major success. “We ended up finishing the schedule against the approved baseline about a year and a half ahead of schedule and obviously $300 million, obviously against the approved baseline now and under budget. We’re very pleased with the successes we’ve had on the K-25 project in the last couple of years.” UCOR referred request for comment to DOE.
