Kenneth Fletcher
WC Monitor
12/5/2014
A strategy plan for dealing with mercury contamination at Oak Ridge has been completed by the Department of Energy and regulators, and DOE is moving forward with design work for a new treatment plant in hope of stating of construction in 2017, according to acting DOE Oak Ridge EM Manager Sue Cange. DOE, the Environmental Protection Agency and the Tennessee Department of Environment finished the plan this year, and a key part of that strategy will be a new facility to treat storm water exiting the Y-12 national security complex at Outfall 200. The facility has two purposes, according to Cange. “One is we anticipate that we will further reduce the concentration of mercury in the Upper East Fork of Poplar Creek. The second is it is a necessary planning step for us before we begin demolition of the former mercury use buildings in earnest, as well as the remediation that follows in digging up the soils,” she told WC Monitor.
Mercury was used in large quantities at Y-12 as part of the production process for nuclear weapons, but more than a half century later problems persist with mercury releases off site that are mainly a result of storm water discharges into local waterways. While the mercury contamination has been longstanding area of concern for regulators, Congress and the Department, in recent years there has been a renewed emphasis on cleanup of the mercury at the site.
The new treatment plant to process storm water exiting Y- 12 through Outfall 200 is necessary before demolition can begin on three buildings at Y-12 where mercury is concentrated—Alpha-4, Beta-4, and Alpha-5. “That will disturb the environment and we expect it will create a release mechanism for more mercury to go into the environment,” Cange said. “There are a lot of control measures that we put in place before we demolish a building, but this mercury treatment facility is an important part of these control measures that will be necessary to make sure we capture and treat this increase of mercury flux that we expect in waterways.”
Plant Will Be Modular and Scaleable
The new facility will be designed to be both modular and scaleable, so that its initial operations can be evaluated and treatment systems or capacity can be added if mercury concentrations need to be further reduced. For example, changes may be necessary depending on the impacts of D&D work at Y-12 on mercury contamination. “Our desire is to design it and build it in a way that we can evaluate its performance and then make modifications if necessary so that we don’t overdesign or overbuild a facility that wouldn’t be necessary,” Cange said. She noted: “There has been some work by the design team at the bench scale in the laboratories and based on their prior experience, so there is a basis for what we’re doing. But we really want to be able to evaluate its performance at the full scale.”
When announcing plans for the facility last year, DOE said that it could start operation in 2020 at a cost of about $120 million. “We are still working towards that with a construction start in late 2017 or perhaps early 2018 depending on a number of factors,” Cange said. Design work is being performed through Oak Ridge cleanup contractor URS CH2M Oak Ridge, LLC, which has reached back to CH2M Hill to perform the design. DOE has not made a decision as to whether construction of the facility will be a DOE direct contract or a UCOR subcontract, Cange said. Oak Ridge is preparing to send the Critical Decision-1 package for the project to DOE headquarters for approval, and is working concurrently with EPA and TDEC on the required Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) decisionmaking documentation. DOE must amend the existing interim record of decision for the site to include the mercury strategy.
Other Mercury Reduction Options Under Consideration
DOE has also identified a number of different activities in addition to the Outfall 200 plant that could reduce mercury contamination. “One example is we are looking at removing some of the mercury contaminated sediments that are in the Upper East Fork of Poplar Creek,” Cange said. “We’re also looking at things like changing the ecosystem of the water itself, doing some chemical manipulation of the water to see if that creates a different environment for fish that don’t bio accumulate mercury.”
Finding various options is part of the strategy’s adaptive management approach, Cange said. “We are identifying many different activities that could help reduce the mercury, we are doing our studies and evaluations, we’re moving out with some,” she said. “We’ll continue in this cycle of evaluating and revising as necessary to bring us to where we need to be, the reduction of the mercury concentration in the waterway so that eventually when the cleanup at Y-12 is complete we can hopefully remove the fish advisories.”
