Purpose:

Groundwater contaminated with chlorinated solvents, either as dense non-aqueous phase liquids (DNAPL) or dissolved components, is a widespread problem at many Department of Defense (DoD) installations. Currently, the pump-and-treat technique is the most commonly used groundwater containment and remediation method. This technique alone is very costly and can lead to groundwater remediation proceeding for several decades. It also may be virtually impossible to know when or if an aquifer will ever reach regulatory cleanup standards. As a potential remediation alternative, DUS/HPO (initially researched and developed by the Department of Energy - Lawrence Livermore National Laboratory) can destroy contaminants in the subsurface. The purpose of this DUS/HPO pilot project is to demonstrate that DNAPL contaminants can be destroyed in-situ.

Description:

The primary objective of this project will be to determine if this technology can remediate the contaminated groundwater to below recommended cleanup standards. DUS/HPO utilizes the proven experience of heating large volumes of soil and groundwater to temperatures near the boiling point of water for the in-situ destruction of the volatile organic compounds. Steam and oxygen are injected together, building a heated oxygenated zone in the subsurface. When injection is halted, steam condenses and contaminated groundwater returns to the heated zone. The contaminated groundwater then mixes with the heated condensate and oxygen, destroying the dissolved contaminants. The process forms non-toxic byproducts, such as carbon dioxide, chloride ions, hydrogen, and water vapor. This remediation method takes advantage of more rapid chemical reactions, which occur at elevated temperatures, as well as the large increase in mass transfer rates, which make the contaminants more available for destruction. DUS/HPO may enable the remediation of organic contaminants, including chlorinated solvents, in the soil and groundwater to below maximum capability levels and possibly the potential of more rapid cleanup and closure of contaminated sites.

Benefits:

Current commercial implementation costs for soil and groundwater cleanups range from about $100 to $500 per cubic yard, and it is estimated that by using DUS/HPO soil and groundwater remediation this cost could be reduced to about $50 to $75 per cubic yard. This could yield an average cost savings ratio of about 2 to 6 times over current pump-and-treat costs. Considering the DoD has characterized several hundred sites with solvent-contaminated groundwater, it is estimated that several million dollars could be saved at each site by using the DUS/HPO technology versus using the long-term pump-and-treat systems. (Project Completed - 2007)

Contact:

Ms. Kathy Greene
NFESC, Code ESC411
1100 23rd Avenue
Port Hueneme, CA 93043-4370
Telephone: (805) 982-5284
Fax: (805) 982-5226
E-mail: kgreene@nfesc.navy.mil