THE Department of Energy's cleanup problems are often represented as intractable. The cleanup budget, now the largest single component in DOE's budget, is seen as inadequate, unlikely to decrease, and detrimental to other DOE functions. Although unique problems with poorly contained and characterized radioactive wastes dominate DOE's problems, the issue of spills and plumes of conventional materials such as solvents, fuels, and mixtures of organic materials is significant, too. Estimates have shown that DOE has a $10-billion legacy of such plumes to clean up. The total cost of cleaning Department of Defense and industrial sites across the country is larger still. When Laboratory Director Bruce Tarter established the Earth and Environmental Sciences Directorate in 1994, he challenged us to change the game in environmental cleanup. The story of the Visalia pole yard in this issue of S&TR demonstrates the first success in response to that challenge.|
Plumes of contaminants in groundwater pose several problems: hazards to public safety and health when the water is used, cleanup cost burdens to property owners, and, because of the associated liabilities, transfer of property ownership. While transferring property is not a burden to most DOE sites (which are likely to remain in government possession indefinitely), it is an obstacle to DOD site closure and reuse of valuable lands (such as California's Mare Island or Alameda Naval Air Station).
Remediation steps to date commonly rely on pump-and-treat. That method works well for near-term regulatory compliance (the site owner is doing something in good faith) to control the spread of plumes, but it rarely removes all the contaminants. Toxic compounds in spills have had decades to sink and bind to fine silts and clays. They are unlikely to be removed by simply slowly flushing water through them.
Steam applied to the subsurface environment mobilizes difficult materials such as heavy oils, which can be extracted at greatly accelerated rates. The addition of oxygen through air injection further destroys contaminant materials. (Remember the elementary chemistry lesson that water at 100°ree;C is a very reactive substance.) As an added benefit, heating the subsurface promotes the growth of thermophylic bacteria that move into a warmed region and actively bioremediate remaining traces of contaminants.
The technical success of Visalia resulted from finding a corporate sponsor, Southern California Edison, that was willing to invest the funds up front for a significant deployment of a new technology at the scale ($20 million) required for a substantive engineering and economic test. DOE sites tend to be constricted by budgets annually competing for money to complete scheduled tasks, producing a context in which "experiments of scale" are perceived as activities that divert funds from ongoing remediation or delay tasks required under Records of Decision. A corporation understands the value of accelerating cleanup and moving the liability off its books, which DOD now finds attractive as well.
Lawrence Livermore's role in this project was to develop and demonstrate relevant cleanup and diagnostic techniques on its own site and then transfer the technologies to a corporate partner who owns a Superfund site and to a subcontractor with steam-injection experience. We functioned as a supporting science and technology team, bringing our experience in supercomputer modeling of subsurface flow and reactive transport, rare-gas tracers and electrical tomographic diagnostics, and isotopic analyses to validate results. These tools are not available in the commercial sector, and the processes are not readily done by the academic community, proving that there is a role for a national laboratory in solving this problem. Some of these tools, now in the hands of the industrial participants, are available for use at other sites.
We now are exploring with DOE and other agencies the next possible sites for testing these techniques. At each site, we will encounter a new combination of subsurface variables and a new cocktail of contaminants. The remediation process will have to be validated anew on each site-we have no silver bullets for subsurface contamination.
As we work at these sites, more technology, understanding, and tricks of the trade will move into industrial hands. The rewards for us will be in helping to remove pressing health hazards cost effectively throughout the nation and gaining future support to move on to the next set of "intractable" problems.