Presented August 20, 2015- Presentation Slides
Designing, Assessing, and Demonstrating Sustainable Bioaugmentation for Treatment of DNAPL Sources in Fractured Bedrock by Dr. Charles Schaefer
The presence of DNAPL in fractured bedrock is one of the greatest challenges facing the Department of Defense (DoD) at many chlorinated solvent sites. Identifying the location of DNAPL sources is one of the key challenges at these sites since many of the tools and approaches used for identifying DNAPL sources in overburden materials are not appropriate or have not been demonstrated in fractured bedrock environments. The ability to target DNAPL and to quantify its removal are often crucial for overall remedial effectiveness and assessment.
This ESTCP project focused on applying partitioning tracers to assess DNAPL architecture in fractured rock at Edwards Air Force Base, followed by targeted application of bioaugmentation in fracture zones containing residual PCE DNAPL. Results to date have provided useful insight with respect to DNAPL distribution, suggesting that DNAPL sources in low transmissivity fracture zones may serve as long-term sources in fractured bedrock aquifers. DNAPL dissolution rates were measured during bioaugmentation with demonstrated removal of DNAPL sources in hydraulically conductive fractures.
Seeing Beyond Boreholes: A Geophysical Toolbox for Characterization and Monitoring of Amendment Delivery in Fractured Rock Aquifers by Dr. Lee Slater
This project supports SERDP’s efforts to reduce DoD liabilities by advancing the use of geophysical technologies for the characterization of flow and transport beyond boreholes in contaminated fractured rock systems. Conventional technologies for investigating rock properties, and contaminant flow and transport in the subsurface are typically limited to providing information local to a borehole. Understanding the fate of amendment injections delivered to target contaminant areas requires spatially extensive information that is impractical and cost-prohibitive using direct sampling methods. This problem is exacerbated in fractured rock aquifers due to the heterogeneity in flow and transport caused by fracture zones. This research evaluated the feasibility of cross-borehole time-lapse electrical geophysical imaging constrained by local geophysical observations at boreholes to track the delivery of amendments within a contaminated fracture zone at a DoD site. The presentation describes the development of novel in-borehole infrastructure, data acquisition strategies, and processing approaches required to successfully image amendment transport beyond boreholes. Limitations and best practices for the deployment of geophysical technologies are also be discussed.
Dr. Charles Schaefer is a senior engineer with CDM Smith in Edison, NJ. His areas of research include pore-scale diffusion and mass transfer processes, in situ bioremediation, treatment of emerging contaminants, and electrochemical treatment of drinking water. Dr. Schaefer has served as a Principal Investigator on several SERDP and ESTCP research grants, many of which have focused on chlorinated solvents in bedrock systems. He has authored over 40 peer-reviewed papers and is an active member of the Interstate Technology and Regulatory Council (ITRC). In addition to his research, Dr. Schaefer also serves as a technical consultant on several federal and commercial projects for CDM Smith, many of which address chlorinated solvents in complex geological settings. Dr. Schaefer earned his bachelor’s, master’s and doctoral degrees in chemical and biochemical engineering from Rutgers University, and has nearly 15 years of consulting experience.
Dr. Lee Slater is a professor of near surface geophysics at Rutgers University. Dr. Slater’s current areas of research focus on the development of borehole-based geophysical technologies for improving understanding of rock properties, control flow and mass transport, as well as geophysical monitoring technologies for tracking amendment delivery, and long term biogeochemical alterations caused by contaminant degradation. Dr. Slater has served as the Principal Investigator on several SERDP and ESTCP research grants on the use of geophysical techniques, primarily electrical methods, for investigating flow and transport processes in numerous geological settings. He has authored more than 130 peer-reviewed research papers and book chapters, including several on the application of geophysics in fractured rock environments. He earned a bachelor's degree in Environmental Science from the University of East Anglia in Norwich, United Kingdom (UK), and he holds master's and doctoral degrees in Environmental Science from Lancaster University in Lancaster, UK.