A Recovery Act cleanup project completed in 2011 at the Y-12 nuclear weapons plant appears to have belatedly reduced the mercury levels in the upper part of East Fork Poplar Creek, although federal officials still aren’t ready to declare it a success.
The West End Mercury Area (WEMA) project was among dozens of Oak Ridge projects funded with money from the American Recovery and Reinvestment Act of 2009, and it was one of the most ambitious.
The project was designed to clean up and repair Y-12’s deteriorated storm-sewer system, parts of which date back to the plant’s World War II origins. The system has long been a collection point for Y-12’s on-site mercury pollution — the result of large-scale spills during development of hydrogen bombs in the 1950s and ‘60s — and a conduit for discharges into East Fork Poplar Creek.
The creek originates inside the plant’s boundaries and eventually flows through much of Oak Ridge’s west side. While Y-12’s discharges have improved dramatically over the years, the residual amounts of mercury still exceed standards set forth by the Clean Water Act. And the creek remains posted as a health hazard, a status it’s had for more than 30 years.
According to Laura Wilkerson, an official in the Department of Energy’s Office of Environmental Management in Oak Ridge, the WEMA project directly removed about 54 pounds of elemental mercury from the storm system. In addition, workers were able to seal or repair many of the cracks and holes in the concrete that historically allowed mercury contamination in Y-12 buildings and soil to seep into the storm sewers and be flushed into the creek.
WEMA encountered a few problems along the way. Some areas of the storm system were inaccessible or had crumbled and couldn’t be repaired. Work was stopped for a month at one point because of safety issues with a subcontractor, and there was a fish kill attributed to the work. Also, the project ended up costing about $17.2 million, a few million dollars more than anticipated.
The success of the project has been a topic of debate.
Not surprisingly, the levels of mercury in the creek actually increased while the WEMA work was underway. That’s likely because the cleanup activities stirred up some of the mercury-contaminated sediments and allowed them to migrate with the stormwaters.
Before cleanup of the storm drains began in 2010, the mercury concentration in the water at Station 17 — the sampling point where the East Fork leaves Y-12 property — was about 580 parts per trillion. As work progressed, the numbers went up, and when the field work was completed in 2011 the mercury level was at 800 parts per trillion. It later peaked at about 900 parts per trillion, DOE said.
Since then, there’s been a downward trend, and by the end of 2013, the mercury in the creek was about the same as it was before the WEMA project got started, Wilkerson said. She said the numbers have continued to decline, with some recent samples as low as 200 parts per trillion — a goal of one of the cleanup agreements established by DOE, the U.S. Environmental Protection Agency and the Tennessee Department of Environment and Conservation.
“It looks like it’s getting better,” Wilkerson said, “but we think it’s going to take even longer to prove that it was a success. The indication is positive.”
State officials agree that it’s too early to claim success.
Kelly Brockman, a spokeswoman for TDEC, said state officials observed mercury levels in the creek increasing during the effort to reline the storm sewers and later declining after the work was done. However, she said TDEC “has not observed an appreciable change in the level of mercury in the fish in East Fork Poplar Creek.”
She added: “At this point, it is too early to assess whether or not the WEMA project has impacted the mercury situation in the creek.”
Wilkerson said it’s a complex challenge because reducing the mercury in the creek’s water does not necessarily bring about similar reductions in fish and other aquatic life.
Jason Darby, a project manager in DOE’s environmental office, said over the years — as conditions in East Fork have changed, including water flow — there have been changes in the fish species and their mercury concentrations.
Years ago, the fish species with the highest mercury concentration was the redbreast sunfish, but now the rock bass is at the top of the food chain with the highest concentration of mercury, Darby said. In some cases, the levels of mercury in fish are actually going up, he said.
Multiple mercury-reduction projects are underway or planned, and the Department of Energy is funding some research activities at Oak Ridge National Laboratory to better understand mercury in the environment.
Perhaps the biggest item on the near-term agenda is a new treatment plant at Y-12 near the point — known as Outfall 200 — where mercury from the storm system enters the creek. Design work on the $125 million project is already underway with construction to begin in 2017 and first operations in 2020. The system will reportedly filter up to 1,500 gallons a minute at the head of the creek to remove the mercury before it can pose a downstream hazard.
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