Using a high-organic matter biowall to treat a trichloroethylene plume at the Beaver Dam Road landfill

Authors: NINO DE GUZMAN, G.T. - University Of Maryland; Hapeman, Cathleen; MILLER, P.D. - Natural History Museum - Kansas; MCCONNELL, L.L. - University Of Maryland; Jackson, Dana; KINDIG, D. - Bmt Designers And Planners; TORRENTS, A. - University Of Maryland

Submitted to: Environmental Science and Pollution Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/26/2018
Publication Date: 1/11/2018
Citation: Nino De Guzman, G., Hapeman, C.J., Miller, P., Mcconnell, L., Jackson, D.S., Kindig, D., Torrents, A. 2018. Using a high-organic matter biowall to treat a trichloroethylene plume at the Beaver Dam Road landfill. Environmental Science and Pollution Research. 25:8735-8746. https://doi.org/10.1007/s11356-017-1137-1.
DOI: https://doi.org/10.1007/s11356-017-1137-1

Interpretive Summary: Trichloroethylene (TCE) is a highly-effective industrial degreasing agent and known carcinogen. It was frequently buried improperly in landfills and has subsequently become one of the most common groundwater and soil contaminants in the United States. A common strategy to remediate TCE-contaminated sites and to prevent movement of the TCE plumes into waterways is to construct biowalls which consist of biomaterials and amendments to enhance biodegradation. This approach was chosen to contain a TCE plume emanating from a closed landfill in Maryland. But, predicting the effectiveness of biowalls is often site-specific. Therefore, we conducted an extensive series of laboratory experiments under more realistic conditions with different materials that could be used in the biowall. Our laboratory results showed good agreement with the field results of the constructed biowall. Although a more toxic degradation product vinyl chloride (VC) was formed and was detected downstream and in the laboratory studies, the overall environmental risk of the site decreased by nearly 90%. This work has provided insight into how to enhance degradation and has led to additional studies. This information will be useful to policy makers and land managers who need effective, long-term mitigation strategies.

Technical Abstract: Trichloroethylene (TCE) is a highly-effective industrial degreasing agent and known carcinogen. It was frequently buried improperly in landfills and has subsequently become one of the most common groundwater and soil contaminants in the United States. A common strategy to remediate TCE-contaminated sites and to prevent movement of the TCE plumes into waterways is to construct biowalls which consist of biomaterials and amendments to enhance biodegradation. This approach was chosen to contain a TCE plume emanating from a closed landfill in Maryland. But, predicting the effectiveness of biowalls is often site-specific. Therefore, we conducted an extensive series of batch reactor studies at 12 degrees C as opposed to the typical room temperature to examine biowall fill-material combinations including the effects of zero valent iron (ZVI) and glycerol amendments. No detectable TCE was observed after several months in the laboratory study when using the unamended 4:3 mulch-to-compost combination. In the constructed biowall, this mixture reduced the upstream TCE concentration by approximately 90 % and generated ethylene downstream, an indication of successful reductive dechlorination. However, the more toxic degradation product vinyl chloride (VC), was also detected downstream at levels approximately 10 times greater than the maximum contaminant level (MCL). This indicates that incomplete degradation also occurred. In the laboratory, ZVI reduced VC formation. A hazard quotient was calculated for the landfill site with and without the biowall. The addition of the biowall decreased the hazard quotient by 88%.