Presented March 19, 2015- Presentation Slides
Naturally-occurring biological and abiotic processes contribute to contaminant attenuation in most groundwater aquifers. At sites where the rate of these natural processes is sufficient to meet remediation goals, monitored natural attenuation (MNA) should be implemented. However, strategies are sometimes not apparent to site owners with respect to which approach to follow. That is, if the site does not meet remedial goals using MNA, will enhancing biological reductive dechlorination meet site goals? Or, is the site a good candidate to pursue abiotic degradation? Although guidance exists with respect to technology application, a pragmatic approach supported by a quantitative framework for selecting the most effective bioremediation approach is lacking.
During this project, we determined the relationship between biogeochemical parameters and degradation rates for known degradation pathways. Data from more than 90 sites was used to establish correlations between the naturally attained rate constant and the abundance of specific parameters. Associations were established for parameters such as Dehalococcoides (Dhc) densities, reductase densities, dissolved oxygen, oxidation-reduction potential, magnetic susceptibility, Fe(II), Mn(II), methane, ethane, total organic carbon and others. These associations allowed us to establish a framework using these parameters as the decision logic. This framework has been developed into an easy-to-apply screening tool for use at sites contaminated by chlorinated solvents.
Ms. Carmen Lebrón is a Private Consultant Environmental Engineer with 33 years of experience in research and development dealing with remediation of fuel and chlorinated hydrocarbons. Prior to becoming a Private Consultant, Ms. Lebrón was a Senior Environmental Engineer for the Navy’s Expeditionary Warfare Center (EXWC) in Port Hueneme, CA. During her 32-year Navy tenure, Ms. Lebrón managed multiple (14) SERDP and ESTCP projects on remediation of chlorinated ethenes, use of molecular biological tools (MBTs) as diagnostic tools and monitored natural attenuation (MNA). Ms. Lebron has authored/co-authored over 15 peer-reviewed publications and over 35 technical reports. She holds a B.S. in Biology from the University of Puerto Rico and a master’s degree in Environmental Planning from California State University, Northridge.
Dr. John Wilson has extensive experience in natural attenuation processes and bioremediation. He is currently the Principal Scientist with Scissortail Environmental Solutions, LLC. Dr. Wilson served as a research microbiologist for U.S. EPA at the R.S. Kerr Environmental Research Center in Ada, Oklahoma for 35 years. He has a B.S. in Biology from Baylor University, an M.A. in Microbiology from the University of California at Berkeley, and a Ph.D. in Microbiology from Cornell University. His research at EPA was primarily on the natural attenuation of BTEX compounds, fuel additives and chlorinated solvents, as well as the in-situ bioremediation of chlorinated solvents. He has over 60 publications on these topics. He was a co-author and editor of the EPA’s report titled “A Guide for Assessing Biodegradation and Source Identification of Organic Ground Water Contaminants Using Compound Specific Isotope Analysis (CSIA”). In addition to his research activities, he provided training and technical assistance to EPA regions and state agencies.