Five mercury projects being performed under the American Recovery and Reinvestment Act were completed in February, with URS-CH2M Oak Ridge LLC, or UCOR, issuing the final reports.
The projects ranged from planning new facilities and planning for cost-effective disposition of mercury-contaminated media, to removing old, abandoned tanks containing mercury. All are part of getting ready for an upcoming major focus on mercury cleanup at the Y-12 National Security Complex.
In the area of Y-12 known as the West End Mercury Area, or WEMA, multiple facilities produced a lithium isotope fundamental to the development of the hydrogen weapon. Mercury was used in that process. In those facilities, various amounts of mercury are present in the process pipes and equipment, drains and sumps, soil surrounding the facilities, storm sewers, and stream sediments.
“When they start tearing these buildings down, they have to have a path forward for what to do with the mercury already released to the site soil, water and sediments, as well the potential for additional mercury that could be mobilized when WEMA soils are disturbed during building demolition and soil excavation,” said Project Manager Eric Sliger. “The (U.S. Department of Energy) has long-range plans that show much of this area as open land in the future. For that to happen, treatment systems and technology have to be in place to support the remediation effort and to remove residual mercury contamination to acceptable levels.”
That means, among other things, a water treatment plant, technology demonstrated to be effective in treating Y-12 site soils, and possibly the construction of a fixed or mobile soil stabilization plant will be required.
UCOR’s job was largely to begin planning for these facilities, which will be needed when those buildings start to come down. Two other scopes of work included removing and disposing of five abandoned mercury-contaminated tanks and conducting limited decontamination and decommissioning.
The total funding for all tasks was $10.3 million. UCOR completed its work for approximately $9.5 million, considerably under budget.
Five mercury-contaminated tanks at Y-12 were removed and disposed of. Three were cut up and transported for disposal at the Nevada National Security Site, or NNSS,and two were disposed of in the Y-12 landfill. Three of the tanks had been abandoned as early as the mid-1980s, and some had open pipe penetrations that encouraged small animals to come inside and nest. In addition, the tanks created a human health concern in the warmer months due to the mercury vapors coming from the various tank openings. This work was done safely and under budget by Veterans Contracting Solutions Group LLC, which participated in project planning, safely executed the work, and returned the site to its original condition.
When the tanks were emptied and the contents inspected, two of the tanks were discovered to contain approximately 650 pounds of elemental mercury, which will also be stabilized and sent to NNSS.
- Prepared a conceptual design report for a water treatment system for Y-12’s Outfall 200, and also prepared a draft CD-1 package and a Remedial Design Work Plan.
- Performed sampling, characterization of the WEMA outfalls, and bench-scale water treatability studies in support of the water treatment system conceptual design report. Water samples from base flow and storm flow events were taken and sent for analysis to help determine what treatment technologies will work best for the water treatment system.
- Performed treatability studies for mercury-contaminated soils. Soils were obtained from a Y-12 excavation and sent to three vendors to perform the studies. The goal was to stabilize mercury within the soils so that the soil meets waste acceptance criteria at the Environmental Management Waste Management Facility, which reduces overall costs of disposal. Nine stabilization technologies potentially applicable to the Y-12 site soils were identified.
All work was done with a perfect safety record—not even a first-aid case, according to Sliger. “And this was under some very hazardous conditions,” he said. “I’m proud of all the crews for their dedication to safety and their excellent work on these projects.”
Note: This story first appeared in the March 2013 issue of Public Involvement News, published by the U.S. Department of Energy Oak Ridge Office.