Remediation of TCE-contaminated groundwater by a permeable reactive barrier filled with plant mulch (Biowall)

Lu, Xiaofan; Wilson, John T.; Shen, H. Z.; Henry, Bruce M.; Kampbell, Donald H.

doi:10.1080/10934520701750421

Cited by 14 publications

(11 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Laboratory and field studies show that the plant mulch is a long‐term carbon source to sustain both biotic and abiotic transformation of TCE in the biowall (Kennedy and Everett ; Shen and Wilson ; Shen et al ). The performance of the biowall in attenuating TCE was presented in another paper (Lu et al ), and the monitoring data demonstrate that TCE concentrations were greatly reduced within the biowall, but increased again in the wells immediately downgradient of the biowall. This rebound in TCE concentrations downgradient of the biowall is not well understood, making it difficult to evaluate the remedial performance of the biowall objectively.…”

Section: Introductionmentioning

confidence: 91%

A Tracer Test to Characterize Treatment of TCE in a Permeable Reactive Barrier

Shen¹,

Wilson²,

Lu³

2012

Groundwater Monitoring Rem

Self Cite

View full text Add to dashboard Cite

A tracer test was conducted to characterize the flow of groundwater across a permeable reactive barrier constructed with plant mulch (a biowall) at the OU‐1 site on Altus Air Force Base, Oklahoma. This biowall is intended to intercept and treat groundwater contaminated by trichloroethylene (TCE) in a shallow aquifer. The biowall is 139‐m long, 7.3‐m deep, and 0.5‐m wide. Bromide was injected from an upgradient well into the groundwater as a conservative tracer, and was subsequently observed breaking through in monitoring wells within and downgradient of the biowall. The bromide breakthrough data demonstrate that groundwater entering the biowall migrated across it, following the slope of the local groundwater surface. The average seepage velocity of groundwater was approximately 0.06 m/d. On the basis of the Darcy velocity of groundwater and geometry of the biowall, the average residence time of groundwater in the biowall was estimated at 10 d. Assuming all TCE removal occurred in the biowall, the reduction in TCE concentrations in groundwater across the biowall corresponds to a first‐order attenuation rate constant in the range of 0.38 to 0.15 per d. As an independent estimate of the degradation rate constant, STANMOD software was used to fit curves through data on the breakthrough of bromide and TCE in selected wells downgradient of the injection wells. Best fits to the data required a first‐order degradation rate constant for TCE removal in the range of 0.13 to 0.17 per d. The approach used in this study provides an objective evaluation of the remedial performance of the biowall that can provide a basis for design of other biowalls that are intended to remediate TCE‐contaminated groundwater.

show abstract

Section: Introductionmentioning

confidence: 91%

A Tracer Test to Characterize Treatment of TCE in a Permeable Reactive Barrier

Shen¹,

Wilson²,

Lu³

2012

Groundwater Monitoring Rem

Self Cite

View full text Add to dashboard Cite

show abstract

“…The inclusion of the additional monitoring groundwater wells has been invaluable for determining background analyte concentrations and will be a crucial component for high-quality, long-term data analysis in subsequent years as evidenced elsewhere (FRTR Federal Remediation Technologies Roundtable (2003), Groundwater Services, Inc. 2004, Lu et al 2008, Gilbert et al 2013.…”

Section: Changes To the Biowall Designmentioning

confidence: 99%

Using adaptive management to guide multiple partners in TCE remediation using a permeable reactive barrier

Guzmán

Hapeman

Millner

et al. 2019

Environ. Res. Commun.

View full text Add to dashboard Cite

The US Department of Agriculture-Agricultural Research Service (USDA-ARS) worked together with the University of Maryland, College Park and BMT Designers and Planners (Consultant) to design a biowall to remediate the groundwater of a Superfund site located in Beltsville, MD. The US Environmental Protection Agency (US EPA) oversaw the remediation plan as per the regulations of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) program. A hybrid adaptive management strategy was employed to to guarantee the use of a science-based approach to the remediation efforts, to ensure that new information could be incorporated into the remediation plan, and to avoid the shortcomings of other remediation efforts elsewhere. Laboratory experiments and a historic-data assessment were conducted in conjunction with the monitoring plan to provide the Consultant and USDA with comprehensive feedback, to strengthen and to modify the monitoring and biowall construction plans as the requirements of the site changed. This feedback mechanism was repeated multiple times to make certain that the highest quality and most effective methods were used. The scope of the project also grew to include investigations of the soil microbial community for future structural biostimulation and bioaugmentation activities. While the biowall has reduced the concentration of trichloroethylene (TCE) to levels at or below its Maximum Contaminant Level, work is on-going to improve the functionality of the biowall and to address emerging challenges.

show abstract

“…In addition, the long‐term sustainability of biowall performance was identified as a key regulatory issue by AFCEE () and others (ITRC ; Obiri‐Nyarko et al ). Lu et al () demonstrated field performance at the OU‐1 biowall at Altus Air Force Base (AFB) based on 4 years of monitoring data. Longer term predictions of biowall longevity have typically been based on laboratory studies rather than field data collected from actual biowall sites.…”

Section: Introductionmentioning

confidence: 99%

“…Biowalls have been installed at two areas of the Altus AFB complex: at Operable Unit 1 (OU‐1) and at Spill Site 17 (SS‐17). The OU‐1 biowall was installed in the eastern portion of the base in June 2002 and has been the subject of several field and laboratory studies (Kennedy and Everett ; Lu et al ; He et al ; USEPA ; Lebrón et al ; Shen et al ; Whiting et al ). One focus of this prior research at the OU‐1 biowall was evaluating the potential for abiotic reactions.…”

Section: Introductionmentioning

confidence: 99%

Long‐Term Evaluation of Mulch Biowall Performance to Treat Chlorinated Solvents

Walker

McGuire

Adamson

et al. 2020

Groundwater Monitoring Rem

View full text Add to dashboard Cite

Permeable reactive barriers (PRBs), such as mulch biowalls, have been installed at numerous groundwater cleanup sites, and laboratory and field studies have demonstrated biotic and abiotic processes that degrade chlorinated volatile organic compounds (CVOCs) in groundwater passing through these engineered remedies. However, the longevity of mulch biowalls remains a fundamental research question. Soil and groundwater sampling at seven mulch biowalls at Altus Air Force Base (AFB) approximately 10 years after installation demonstrated the ongoing degradation of CVOCs. Trichloroethene was not detected in five of seven groundwater samples collected from the biowall despite upgradient detections above federal drinking water standards. Microbial sampling established the presence of key dechlorinating bacteria and the abundance of genes encoding specific enzymes for degradation, high methane concentrations, low sulfate concentrations, and negative oxidation‐reduction potential, all indicative of highly reducing conditions within the biowalls and favorable conditions for CVOC destruction via microbial reductive dechlorination. High cellulose content (>79%) of the mulch, elevated total organic carbon (TOC) content in groundwater, and elevated potentially bioavailable organic carbon (PBOC) measurements in soil samples further supports an ongoing, long‐lived source of carbon. These results demonstrate the ongoing and long‐term efficacy of the mulch biowalls at Altus AFB. In addition, concentrations of bacteria, TOC, PBOC, and other geochemical parameters suggest a modest impact of the biowalls downgradient. The continued presence of CVOCs downgradient may be attributable to back diffusion from low‐permeability shale. However, the biowalls continue to provide benefits by removing CVOCs in groundwater, thus reducing further CVOC loading to the downgradient, low‐permeability strata.

show abstract

Remediation of TCE-contaminated groundwater by a permeable reactive barrier filled with plant mulch (Biowall)

Cited by 14 publications

References 9 publications

A Tracer Test to Characterize Treatment of TCE in a Permeable Reactive Barrier

A Tracer Test to Characterize Treatment of TCE in a Permeable Reactive Barrier

Using adaptive management to guide multiple partners in TCE remediation using a permeable reactive barrier

Long‐Term Evaluation of Mulch Biowall Performance to Treat Chlorinated Solvents

Contact Info

Product

Resources

About