- Program Areas
- Installation Energy and Water
- Environmental Restoration
- Munitions Response
- Resource Conservation and Resiliency
- Weapons Systems and Platforms
Assessment of Post Remediation Performance of a Biobarrier Oxygen Injection System at an MTBE Contaminated Site
Kenda Neil | NAVFAC EXWC
This project will evaluate long-term performance of a two-tiered biobarrier system previously used at the 22 Area of Marine Corps Base (MCB) Camp Pendleton to treat methyl tertiary-butyl ether (MTBE) in groundwater. The system used pure oxygen injection/sparging to create a two-tiered biobarrier approach. The project’s objectives are two-fold and include evaluating: (1) if microbial activity as a result of the biobarrier continues to support attenuation of residual MTBE at the site, and (2) if bio-clogging (clogging of the aquifer caused by excess biomass) influenced plume migration and the resulting widening in the neck of the plume. Advanced microbiological tools (i.e., proteomics and metagenomics) and existing site information will be used to achieve these objectives.
Omic analyses (proteomics and metagenomics) provide detailed information on hundreds of microorganisms and their associated metabolizing activity. This project will use findings from proteomic and metagenomic analyses and contrast them with the results obtained using traditional geochemical analyses. Data collected within the radius of influence (ROI) of the biobarriers (mid-plume and leading edge) will be compared statistically using the analysis of variance (ANOVA) approach with data collected upgradient of the biobarriers. The goal is to confirm that the biobarriers changed the microbial communities and the resulting MTBE- degrading peptides are present within the plume. The goal of the metagenomic analysis is to develop a comprehensive listing of microbial species involved in the degradation of MTBEs as well as other organisms that might be influential in syntrophic degradation. This information will help to evaluate the role of continued microbial activity post sparging to support ongoing attenuation of residual MTBE. Further, it is hypothesized that the biosparging system contributed to clogging of the aquifer by the development of microbial biofilms. The metagenomic information may help improve understanding of the effect of these microbial biofilms on the aquifer. Slug tests will also be conducted in order to compare to previously performed slug tests and assess whether the biobarrier impacted the formation’s permeability.
Proteomics data, in addition to system performance data, should help support the Acceptance of Low Threat Closure at the MTBE-contaminated site. Therefore, results from this performance review will impact the 22 Area of MCB Camp Pendleton immediately. More importantly, the information gained through this project will help further improve scientific knowledge on similar MTBE-contaminated sites. Omic technologies provide the line of evidence needed to document natural attenuation. Further, deciphering the effects of biofilms can help users understand plume migration at similar biobarrier sites where limited information is available. Ultimately, use of these monitoring tools for restoration of contaminated groundwater sites will provide the Department of Defense with a better understanding of bioremediation remedies such that improved decisions can be made during restoration activities.