Purpose:

The Department of Defense (DoD) has a critical need for faster, less expensive, and more accurate methods to characterize and monitor volatile organic compounds (VOCs) in the subsurface. Chlorinated solvents in the form of dense non-aqueous phase liquids (DNAPLs) pose the most serious challenge. Failure to adequately define DNAPL source terms often plagues many remediation efforts, potentially wasting limited cleanup dollars and exacerbating the problem by redistributing the contaminant over a larger area. This project will demonstrate and validate an innovative suite of direct push DNAPL characterization and verification tools designed to rapidly delineate DNAPL contamination in the subsurface.

Description:

Collaboration between government and industry in this project brings together an innovative suite of sensor technologies for real-time in situ characterization of DNAPL. The sensors consist of a novel halogen specific detector (XSD) designed to operate downhole behind a membrane interface probe (MIP) that samples the soil formation for VOCs. Moving the detector downhole and measuring while the direct push probe is continuously advanced will provide an order of magnitude increase in the spatial resolution (from feet to inches) when compared to previous methods that use a MIP coupled to an uphole detector. A second sensor system that makes use of a very high repetition rate microchip laser to detect small scale spatial variability in fluorescence from petroleum products or humic substances that may be dissolved in DNAPL will provide even greater spatial resolution (tenths of inches). Finally, a third sensor system that employs a video imaging system integrated into a push probe will provide direct visual verification of DNAPL source zones indicated by the XSD and fluorescence measurements. This suite of sensors will be validated through demonstrations at three DoD contamination sites.

Benefits:

This project directly addresses the DoD need for improved capabilities to delineate and remediate DNAPL (ganglia and free product phase) in the subsurface environment. Site characterization often accounts for approximately one-third of the total cost of remediation at DoD sites. Conservative estimates suggest that 50 percent or greater reduction in the cost of site characterization could be realized through the approach to be demonstrated. In addition, significant savings in both time and money are anticipated as a result of more effective remedial designs that result from the improved knowledge of site characteristics provided by this approach. (Anticipated Project Completion - 2005)

Contact:

Dr. Stephen Lieberman
SPAWAR Systems Center, San Diego
53475 Strothe Rd.
Division D-361
San Diego, CA 92152
Telephone: (619) 553-2778
Fax: (603) 909-8049
E-mail: lieberma@spawar.navy.mil