DYNAMIC UNDERGROUND STRIPPING AND HYDROUS PYROLYSIS/OXIDATION FOR REMEDIAITON OF DNAPLS

摘要

IT Corporation and Integrated Water Resources, Inc. (IWR) have teamed to design, construct and operate thermal remediation systems for the removal of DNAPLs. Individually or as a team IT and IWR have used thermal remediation technologies developed at Lawrence Livermore National Laboratory and licensed by IWR from the University of California to remediate a wide range of contaminants throughout the United States and Canada. This paper will present two case histories for thermal remediation of DNAPL-like heavy oils and chlorinated solvents. The first application of thermal remediation employed steam injection to mobilize heavy DNAPL-like oils at the Puget Sound Naval Shipyard, Bremerton, Washington. The site was impacted to a depth of 100 feet below ground surface by No. 6 fuel oil, which has viscosity's and density's similar to coal tar and migrated below the groundwater surface like heavy DNAPLs. Steam was injected into the sandy till soils to mobilize and volatilize the heavy oil for collection in liquid and vapor extraction wells. During the 9-month operational period more than 35,000 gallons were either removed or degraded by enhanced bioremediation. The second application was used to remove the solvents PCE and TCE from a contaminated aquifer at the former Solvent Storage Tank area at Savannah River Site, Aiken, South Carolina. The program for this site involves the application of: 1. Dynamic Underground Stripping, a combination of steam injection and vapor and groundwater extraction; and 2. Hydrous Pyrolysis/Oxidation (HPO) -Destruction of underground contaminants through oxidation in the presence of injected steam. The target zone for steam injection extends over an area of approximately 100 feet by 100 feet, from 20 feet below ground surface to 160 feet below ground surface. Approximately 13,000 kg of the contaminants PCE and TCE have been identified distributed throughout this volume. Sands and silts comprise the majority of the subsurface volume, with several thin silt-clay layers. Active steam operations are expected to take 6 months, with an additional 3 months of intermittent steam and air injection to keep the formation both hot and oxygenated to enhance in situ destruction of dissolved phase contaminants by Hydrous Pyrolysis/Oxidation. In both instances an innovative design was implemented to makes use of site supplied steam to reduce cost. Other innovations included the use of steam driven jet pumps for groundwater extraction, electrical resistance tomography to track, in real time, the steam front migration and a regenerative thermal oxidizer for vapor treatment.