Research microbiologist Dr. Wendy J. Davis-Hoover and colleagues at EPA have developed an advanced in situ bioremediation process to treat contaminated soil. They use encapsulated sodium percarbonate, a patented product they call “Slow-releasing Oxygen Source” (SOS), to provide a slow, constant and controlled release of oxygen into subsurface soil to stimulate the aerobic degradation of pollutants, such as methyl tertiary butyl ether (MTBE) and benzene, toluene, ethylbenzene and xylene (BTEX). The EPA researchers adapted hydraulic fracturing from the oil drilling industry to access the subsurface. A hole is drilled into the contaminated area. High pressure water cracks the subsurface layers. Microorganisms are then introduced into the fractures, where they begin to degrade the pollutants. The SOS is delivered in the hydraulic fracturing water directly to the area of contamination. The advantages of hydraulic fracturing combined with the SOS compared to standard bioremediation methods, according to EPA, include lower operational costs, because equipment maintenance is not required. No pumps or meters that tend to freeze or fail are used. The process does not mobilize or spread pollutants, and the slow release of oxygen provides a long-term treatment. Test results indicate that SOS may be the preferred method of supplying oxygen at a remote site or a site with operational problems. EPA is ready to license the SOS product and is seeking potential licensees to market it. Contact Dr. Wendy J. Davis-Hoover, NRMRL/NHSRC of ORD of EPA, Tel: 513-569-7206, Fax: 513-569-7879, or Email: Davis-Hoover.Wendy@epamail.epa.gov