From Ground Water Currents, June 1996, Issue No. 15

Regulatory Closure After Innovative Technology Remediation

At the Lawrence Livermore National Laboratory (LLNL) in Livermore, California, environmental regulatory agencies have concurred that remediation of gasoline contaminated soil above the water table is complete. This is the first formal regulatory closure of a non-excavation cleanup activity at the Laboratory's Livermore site since clean-up began in 1988. A relatively inexpensive innovative technology known as Dynamic Underground Stripping was used to clean up 29,000 liters of gasoline that leaked into the ground from an underground gasoline storage tank a number of years ago. Researchers from LLNL and the University of California (UC) at Berkeley teamed up to demonstrate a unique and new combination of technologies that comprise Dynamic Underground Stripping. The process employs vapor extraction during underground steaming and electrical heating. The heat is applied by steam and electricity to vaporize trapped contaminants in the soil.

Once vaporized, the contaminants are removed by vacuum extraction. The processes are monitored and guided by underground imaging. Dynamic stripping removed most of the gasoline (29,000 gallons) in only nine months of active time and at a cost $11 million for treatment and the supporting research. It is estimated that the same cleanup would now cost $6 million over six months. This is in contrast to excavation biodegradation that would have taken a year and cost about $30 million. Pump and treat activities have been estimated to take 200 years at this site with cost ranging from $20 million to $60 million.

The U.S. EPA, the California Department of Toxic Substances Control and the Regional Water Quality Control Board-San Francisco Bay Region concluded that soil cleanup efforts above the water table at the site of the gasoline spill were no longer necessary and that the soil remediation efforts have met or exceeded "Applicable or Relevant and Appropriate Requirements" as stated in the Livermore Site Record of Decision agreed to by the regulatory agencies in 1992. Cleanup of contaminated ground water continues. For more information, contact Gordon Yano at 510-423-3117.