How Heat Can Enhance In-situ Soil and Aquifer Remediation: Important Chemical Properties and Guidance on Choosing the Appropriate Technique

The EPA Regional Ground Water Forum is a group of EPA professionals representing Regional Superfund and Resource Conservation and Recovery Act (RCRA) Offices, committed to the identification and resolution of ground-water issues impacting the remediation of Superfund and RCRA sites. Innovative technologies for subsurface remediation, including in-situ techniques based on heating the subsurface to enhance the recovery of organic contaminants, are being evaluated more often for specific sites as the limitations to the conventionally-used techniques are recognized. The purpose of this Issue Paper and the three companion Issue Papers (Davis, 1997a, b, c) is to provide to those involved in assessing remediation technologies some basic information on the thermal remediation techniques. In order to understand how heat can enhance a remediation process, it is essential to understand the properties of organic contaminants that affect their recovery. Thus, this Issue Paper contains in-depth information on the properties of some common organic contaminants which can affect their movement in and recovery from the subsurface, as well as information on how these properties are affected by temperature. Then, some basic information on which of the heat-based remediation techniques may be most appropriate for the subsurface conditions and the contaminants is also provided, as well as a comparison of the heat-based techniques to other in-situ remediation techniques. The three companion Issue Papers have been written to provide an explanation of how each of the three general types of processes (steam or hot air injection, electrical heating, and hot water injection) works, as well as preliminary information on the design of a system and some estimates of the expected costs. Thus, once the ground-water remediation specialist has determined which of the thermal methods may be appropriate for a particular site, the Issue Paper on that method may be consulted for more detailed information on how the process may be applied.