Environmental Health - Toxic Substances Hydrology Program
Pools of dense non-aqueous phase liquids (DNAPLs) in the subsurface can serve as a long-term source for dissolved contaminant plumes at many contamination sites. Debates regarding whether partial removal of these pools contributes to effective cleanup technology were calmed when Toxics Program scientists, in conjunction with the U.S. Navy, demonstrated that the near-complete removal of a DNAPL pool in the subsurface by engineered methods facilitated the rapid collapse of a chlorinated solvent plume at the Submarine Base Kings Bay, Georgia. The removal was achieved by in situ chemical oxidation with Fenton's reagent that was injected into the subsurface through an array of injection wells. The removal of the DNAPL at Kings Bay has lowered the estimated time for site remediation from 35 years or more (with the previous pump-and-treat system) to approximately 5 years, and lowered the estimated remediation costs from $30 million to $5 million. Similar cost savings could be realized at other sites contaminated with chlorinated solvents, a common DNAPL, using the same approach to removing DNAPL that is acting as a long-term source of contamination.
USGS involvement with the Fenton's reagent injection at Kings Bay was to