Biodegradation potential of chlorinated solvents in ground water at the Naval Surface Warfare Center, Louisville, Kentucky, July 1999 to February 2000

The U.S. Geological Survey, in cooperation
with the U.S. Department of the Navy, Southern
Division Naval Facilities Engineering Command,
investigated the potential for biodegradation of
chlorinated solvents in ground water at the Naval
Surface Warfare Center (also known as the Naval
Ordnance Station, or the station), Louisville,
Kentucky. The subsurface down to at least 100 feet
at the station is characterized, from shallowest to
deepest, by overburden deposits, a shale layer, and
limestone. In general, all of the strata are poorly
permeable. The permeable zones of the overburden
and the limestone make up the overburden aquifer
and the bedrock aquifer, respectively. Observed
concentrations of redox-sensitive solutes suggest
that the predominant anaerobic terminal electron
accepting process in the overburden aquifer can
shift between iron reduction and sulfate reduction,
possibly as a result of rainfall-induced oxidation
events. Daughter-product concentrations and
laboratory experiments indicate that a variety of
mechanisms, including reductive dechlorination
and cometabolic oxidation, appear to be actively