Over the last 10  years, DOD has invested approximately $20 billion for the environmental  restoration of contaminated sites, including remediation of contaminated  groundwater on and around active, closing, and formerly used defense  facilities. DOD Has Implemented or Field-tested a Wide Range of Technologies to Remediate Sites Contaminated with Groundwater

DOD has implemented or field-tested all of the 15 types of generally  accepted technologies currently available to remediate groundwater. DOD guidance  directs department officials to consider cost-effectiveness and  performance when selecting technologies for cleanup. According to department officials, DOD selects the most suitable  technology to clean up a contaminated site based on a number of factors,  including the type of contaminant, its location and concentration at  different levels in the subsurface, and its chemical and physical  composition. See table 2 for information  on which of the 15 technologies can potentially treat each of DOD’s  contaminants of concern. Most of these  new approaches are being used or field-tested by DOD and involve novel  materials that are applied to contaminated sites using existing  technologies. DOD Supports the Development of New Technologies with the Commercial Sector through Several Programs

We found that DOD is actively involved in researching and testing new  approaches to groundwater remediation, largely through its efforts to  develop and promote the acceptance of innovative groundwater  remediation technologies. In  particular, the DOD-funded Strategic Environmental Research and  Development Program (SERDP) supports public and private research on  contaminants of concern to DOD and innovative methods for their  treatment, among other activities. Agency Comments

DOD generally agreed with the content of the report, stating that the report  is an accurate summary of DOD’s use and field tests of remedial  technologies; DOD also provided technical clarifications that we have  incorporated, as appropriate. GAO staff who made major contributions to this report are  listed in appendix V.

Objectives, Scope, and Methodology

This report (1) describes the groundwater remediation technologies that  the Department of Defense (DOD) is currently using or field-testing and (2)  examines whether any new groundwater remediation technologies are  being used outside the department or are being developed by commercial  vendors that may have potential for DOD’s use, and the extent to which  DOD is researching and developing new approaches to groundwater  remediation. We did not consider any modifications or enhancements to  a technology, such as variations in the material or equipment used during  treatment, to be a separate technology. The contaminated water  flows into the wetland and is processed by wetland plants and  microorganisms to break down and remove the contaminants. 6.
Why GAO Did This Study

To date, the Department of Defense (DOD) has identified nearly 6,000 sites at its facilities that require groundwater remediation and has invested $20 billion over the past 10 years to clean up these sites. In the past, DOD primarily used "pump-and-treat" technologies to contain or eliminate hazardous contaminants in groundwater. However, the long cleanup times and high costs of using pump-and-treat technologies often make them expensive and ineffective for groundwater remediation. As directed by Public Law 108-375 and as agreed, GAO (1) described current DOD groundwater remediation technologies and (2) examined whether any new technologies are being used or developed outside the department that may have potential for DOD's use and the extent to which DOD is researching and developing new approaches to groundwater remediation. GAO provided the Department of Defense with a draft copy of the report for its review and comment. DOD generally agreed with the contents stating that the report is an accurate summary of DOD's use and field tests of remedial technologies. DOD also provided technical clarifications that have been incorporated, as appropriate.

What GAO Found

DOD has implemented or field-tested all of the 15 types of generally accepted technologies currently available to remediate contaminated groundwater, including several alternatives to pump-and-treat technologies. Some of these technologies, such as bioremediation, introduce nutrients or other materials into the subsurface to stimulate microorganisms in the soil; these microorganisms consume the contaminant or produce byproducts that help break down contaminants into nontoxic or less-hazardous materials. DOD selects the most suitable technology for a given site on the basis of several factors, such as the type of contaminant and location in the subsurface, and the relative cost-effectiveness of a technology for a given site. DOD has identified a number of contaminants of concern at its facilities, each of which varies in its susceptibility to treatment. GAO did not identify any alternative groundwater remediation technologies being used or developed outside DOD that the department has not considered or used. Most of the new approaches developed by commercial vendors and available to DOD generally use novel materials applied to contaminated sites with existing technologies. DOD actively researches and tests new approaches to groundwater remediation largely by developing and promoting the acceptance of innovative remediation technologies. For example, DOD's Strategic Environmental Research and Development Program supports public and private research on contaminants of concern to DOD and innovative methods for their treatment.