Steam Enhanced Extraction of Chlorinated Solvents in Fractured Media

A brief overview of the current five Steam Enhanced Remediation field projects implemented by SteamTech will be given. Then, the treatability study at Edwards AFB, Site 61 will be presented. The site consist of fractured granite bedrock with substantial TCE and BTEX contamination. The field demonstration used steam injection in a central well combined with vapor and liquid extraction from four corner wells. Steam was injected for 60 days, while extraction was done 10 days prior to injection and a week after cessation of steam injection. The site heat-up was documented using digital thermocouples and electrical resistivity tomography. Preliminary results are as follows: (1) Steam can be used to heat the fractured granite rock, and to flush contaminants towards extraction wells, (2) The vadose zone vacuum extraction removed the bulk of the chemical mass at this site, (3) Effluent concentrations in both liquid and vapor phases were increased significantly in extraction holes, even when the holes stayed below steam temperature, and (4) Approximately 700 pounds of contaminants were extracted. Overall, the results are very promising for thermal remediation in fractured rock.