Gorm Heron, Ph.D. Vice President & Senior Engineer TerraTherm, Inc.

Dr. Heron is Vice President and Senior Engineer with TerraTherm, Inc. He is responsible for site evaluation and treatment design. He specialized in a broad rage of thermal remediation methods, including Thermal Conduction Heating and Steam Enhanced Extraction. From 1995 to 1998, Dr. Heron conducted research on thermal remediation at the US EPA lab in Ada, Oklahoma, and at University of California at Berkeley. He was the lead engineer with SteamTech Environmental Services from 1999 to early 2004, where he designed and implemented field-scale steam and electrical heating systems. He is based in south central California.

Presentation Description
Status of Thermal In-Situ Remediation Technologies for CVOC DNAPL
The principles of thermal remediation will be reviewed, including dominant changes in the physical and chemical properties of contaminants during heating, and methods for delivering heat and for recovery of the contaminants at the field scale. Three case studies will be presented to illustrate state-of-the-art field applications in tight clay, permeable sand aquifers, and fractured rock.

The first case study is a deep fractured rock site in southeastern US, treated to 90 ft using thermal conduction heating (TCH). It was demonstrated that the gneiss bedrock heated as least as fast as the overlying saprolite and alluvial material. Target temperatures of 100 oC were reached in the entire treatment volume, and approximately 15,000 lbs of TCE were removed. TCE concentrations were reduced from DNAPL-levels to an average of 0.017 mg/kg in soil and rock samples, after 150 days of thermal treatment.

The second case study covers eight chlorinated volatile organic compound (CVOC) source area treated simultaneously using TCH at Dunn Field in Memphis, TN. A volume of 49,900 cubic yards of soil was treated in 174 days of heating. After removal of 12,500 lbs of CVOC mass, soil concentrations in all eight area met the remedial standards. Soil CVOC concentrations were reduced from levels as high as 2,850 mg/kg to below 1 mg/kg in all samples, with an overall mass reduction on the order of 99.99%. Unit treatment costs were $79 per cubic yard.

The third case study presents a unique combination of steam enhanced extraction (SEE) and TCH at a site in Denmark. A thick PCE-impacted clay was heated by TCH, while an underlying high-yield aquifer was heated and treated using SEE. The thermal remediation took place under an active, occupied dry cleaning facility. Extremely limited access was overcome by the use of compact drilling machines and custom designed conveyance piping. Again, stringent remedial goals were achieved. A detailed survey confirmed that no significant settlement or damage to the building took place.

Thermal technologies have matured and consistent results are being produced using both TCH and SEE. It is now common that DNAPL source areas are completely restored, with removal of between 99 and 100% of the mass.