Objective:
Most of the technologies used to treat dense nonaqueous phase liquids (DNAPL) are not applicable in fractured materials. Unless treatment removes mass from the fractured rock matrix, back-diffusion of contaminants can continue for hundreds of years following treatment. The objective of this project is to demonstrate and validate a DNAPL remediation technique for fractured bedrock sites and to provide Department of Defense (DoD) remedial project managers (RPM) and site owners guidance on (1) When does it make sense to attempt aggressive remediation? and (2) What type of performance is to be expected from an aggressive technology application such as thermal conductive heating (TCH)? Such guidance will help practitioners avoid misperceptions regarding what is attainable in terms of mass removal, reduction of aqueous phase contaminant flux, reduction of aqueous phase concentrations, and reduction in source zone lifespan. Technology Description: TCH involves the placement of heater wells that have the capacity of operating at temperatures as high as 800º C, thereby raising the temperature of the surrounding rock through conductive heating. TCH is uniquely poised for fractured bedrock remediation because of its ability to uniformly distribute heat, insensitivity to heterogeneity and electrical conductivity, insensitivity to the type of soil or rock being heated, and versatility in reaching and maintaining uniform temperatures. In this project, investigators will conduct a treatability study to calculate removal rates and establish necessary treatment temperatures and duration in the field, both of which are necessary for successful transferability to other sites. The field demonstration will validate a heating strategy, achievable heating rates and fluid control, and matrix heating and desaturation. The microbial characterization evaluation at the site before and after TCH application will focus on changes in the population capable of reductive dechlorination. Technical guidance for TCH application in fractured rock settings also will be developed. Expected Benefits: A DNAPL source zone survey conducted by the Navy illustrated that 29% of the cases submitted were fractured media sites, and the average site had more than 100,000 cubic feet of impacted material. It is estimated that DoD owns 870 DNAPL source zone fractured bedrock sites and is responsible for the remediation of 3.22 million cubic yards of fractured bedrock material. Implementing TCH could potentially lead to significant cost savings over chemical oxidation and surfactant enhanced removal. Furthermore, since effective bedrock remediation is dependent on removing contaminants from the rock matrix, TCH offers distinct advantages over fluid flushing technologies (e.g., oxidant flushing and surfactant flushing) and other thermal technologies that are adversely affected by geological heterogeneity. (Anticipated Project Completion - 2011) Principal Investigator: Ms. Carmen Lebrón Naval Facilities Engineering Service Center Restoration Development Branch 1100 23rd Avenue, ESC-411 Port Hueneme, CA 93043-4370 Telephone: (805) 982-1616 Fax: (805) 982-4304 E-mail: carmen.lebron@navy.mil | 
