1
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Carroll KC, Brusseau ML, Tick GR, Soltanian MR. Rethinking pump-and-treat remediation as maximizing contaminated groundwater. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 918:170600. [PMID: 38336056 DOI: 10.1016/j.scitotenv.2024.170600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 01/09/2024] [Accepted: 01/29/2024] [Indexed: 02/12/2024]
Abstract
For over half a century, the United States has developed water quality regulations (e.g., Safe Drinking Water Act), which has been accompanied by innumerable advances in contaminant transport and fate, site characterization, and remediation. Since the 1980s, "pump-and-treat" techniques have been the most widely used methods for groundwater contamination remediation. By 1982, pump-and-treat was included in 100 % of the U.S. Superfund groundwater remedy decisions, but applications decreased continuously after 1992. This was likely associated with the documented limitations of pump-and-treat for achieving complete remediation with site closure. Several factors can limit the effectiveness of pump-and-treat, a primary one being that contaminant mass residing in NAPL, sorbed, and low-permeability matrices is not removed in an effective or efficient manner. This ineffectiveness leads to extended cleanup times and the generation of enormous volumes of extracted groundwater, in effect creating conditions of maximizing the amount of contaminated groundwater needing treatment. We highlight a means by which to reassess our approach to remediation by recognizing that pump-and-treat, due to its well-documented limitations, often maximizes the generation of contaminated groundwater.
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Affiliation(s)
- Kenneth C Carroll
- New Mexico State University, Department of Plant and Environmnetal Sciences, Las Cruces, NM, USA.
| | - Mark L Brusseau
- Environmental Science Department, University of Arizona, Tucson, AZ 85721, USA
| | - Geoffrey R Tick
- Department of Geological Sciences, University of Alabama, Tuscaloosa, AL 35487, USA
| | - Mohamad R Soltanian
- Department of Geosciences, Department of Environmental Engineering, University of Cincinnati, Cincinnati, OH, USA
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2
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Mosthaf K, Rosenberg L, Broholm MM, Fjordbøge AS, Lilbæk G, Christensen AG, Bjerg PL. Quantification of contaminant mass discharge from point sources in aquitard/aquifer systems based on vertical concentration profiles and 3D modeling. JOURNAL OF CONTAMINANT HYDROLOGY 2024; 260:104281. [PMID: 38061244 DOI: 10.1016/j.jconhyd.2023.104281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 10/16/2023] [Accepted: 12/01/2023] [Indexed: 01/05/2024]
Abstract
Point sources with contaminants, such as chlorinated solvents, per- and polyfluoroalkyl substances (PFAS), or pesticides, are often located in low-permeability aquitards, where they can act as long-term sources and threaten underlying groundwater resources. We demonstrate the use of a 3D numerical model integrating comprehensive hydrogeological and contamination data to determine the contaminant mass discharge (CMD) from an aquitard into the underlying aquifer. A mature point source with a dissolved chlorinated solvent in a clayey till is used as an example. The quantitative determination is facilitated by model calibration to high-resolution vertical concentration profiles obtained by direct-push sampling techniques in the aquifer downgradient of the contaminant source zone. The concentration profiles showed a plume sinking with distance from the source characteristic for such aquitard/aquifer settings. The sinking is caused by the interplay between infiltrating water and horizontal groundwater flow. The application of 3D solute transport modeling on high-resolution profiles allowed for determining the infiltration rate, the hydraulic conductivity in the aquitard, and, ultimately, the CMD. Different source zone conceptualizations demonstrate the potential effects of fractures and sorption in source zones in aquitards on CMD development. Fractures in the aquitard had a minor influence on the current CMD determined with the presented approach. Still, fractures with hydraulic apertures larger than 10 μm were crucial for the temporal development of the CMD and plume. A thorough characterization of the source zone conditions combined with high-resolution concentration profiles and detailed modeling is valuable for shedding light on the probable future development of groundwater contamination arising from sources in aquitard/aquifer settings and evaluating remedial actions.
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Affiliation(s)
- Klaus Mosthaf
- Department of Environmental and Resource Engineering, Technical University of Denmark, Bygningstorvet, 2800 Kgs. Lyngby, Denmark.
| | - Louise Rosenberg
- Department of Environmental and Resource Engineering, Technical University of Denmark, Bygningstorvet, 2800 Kgs. Lyngby, Denmark
| | - Mette M Broholm
- Department of Environmental and Resource Engineering, Technical University of Denmark, Bygningstorvet, 2800 Kgs. Lyngby, Denmark
| | - Annika S Fjordbøge
- Department of Environmental and Resource Engineering, Technical University of Denmark, Bygningstorvet, 2800 Kgs. Lyngby, Denmark
| | - Gro Lilbæk
- NIRAS, Sortemosevej 19, 3450 Allerød, Denmark
| | | | - Poul L Bjerg
- Department of Environmental and Resource Engineering, Technical University of Denmark, Bygningstorvet, 2800 Kgs. Lyngby, Denmark
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3
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Puigserver D, Herrero J, Carmona JM. Mobilization pilot test of PCE sources in the transition zone to aquitards by combining mZVI and biostimulation with lactic acid. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 877:162751. [PMID: 36921871 DOI: 10.1016/j.scitotenv.2023.162751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 02/05/2023] [Accepted: 03/05/2023] [Indexed: 05/06/2023]
Abstract
The potential toxic and carcinogenic effects of chlorinated solvents in groundwater on human health and aquatic ecosystems require very effective remediation strategies of contaminated groundwater to achieve the low legal cleanup targets required. The transition zones between aquifers and bottom aquitards occur mainly in prograding alluvial fan geological contexts. Hence, they are very frequent from a hydrogeological point of view. The transition zone consists of numerous thin layers of fine to coarse-grained clastic fragments (e.g., medium sands and gravels), which alternate with fine-grained materials (clays and silts). When the transition zones are affected by DNAPL spills, free-phase pools accumulate on the less conductive layers. Owing to the low overall conductivity of this zone, the pools are very recalcitrant. Little field research has been done on transition zone remediation techniques. Injection of iron microparticles has the disadvantage of the limited accessibility of this reagent to reach the entire source of contamination. Biostimulation of indigenous microorganisms in the medium has the disadvantage that few of the microorganisms are capable of complete biodegradation to total mineralization of the parent contaminant and metabolites. A field pilot test was conducted at a site where a transition zone existed in which DNAPL pools of PCE had accumulated. In particular, the interface with the bottom aquitard was where PCE concentrations were the highest. In this pilot test, a combined strategy using ZVI in microparticles and biostimulation with lactate in the form of lactic acid was conducted. Throughout the test it was found that the interdependence of the coupled biotic and abiotic processes generated synergies between these processes. This resulted in a greater degradation of the PCE and its transformation products. With the combination of the two techniques, the mobilization of the contaminant source of PCE was extremely effective.
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Affiliation(s)
- Diana Puigserver
- Department of Mineralogy, Petrology and Applied Geology. Faculty of Earth Sciences, University of Barcelona (UB), Water Research Institute (IdRA-UB), Serra Húnter Tenure-elegible Lecturer, C/ Martí i Franquès, s/n, E-08028 Barcelona, Spain.
| | - Jofre Herrero
- Department of Mineralogy, Petrology and Applied Geology, Faculty of Earth Sciences, University of Barcelona (UB), Water Research Institute (IdRA-UB), C/ Martí i Franquès, s/n, E-08028 Barcelona, Spain.
| | - José M Carmona
- Department of Mineralogy, Petrology and Applied Geology, Faculty of Earth Sciences, University of Barcelona (UB), Water Research Institute (IdRA-UB), C/ Martí i Franquès, s/n, E-08028 Barcelona, Spain.
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4
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Schaefer CE, Lavorgna GM, Lippincott DR, Nguyen D, Schaum A, Higgins CP, Field J. Leaching of Perfluoroalkyl Acids during Unsaturated Zone Flushing at a Field Site Impacted with Aqueous Film Forming Foam. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:1940-1948. [PMID: 36689630 DOI: 10.1021/acs.est.2c06903] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
While several studies have focused on perfluoroalkyl acid (PFAA) leaching from soils, field studies evaluating the relationship between PFAA mass removal and porewater concentrations as the PFAA source becomes depleted are lacking. Herein, in situ water flushing was performed at a site historically impacted with AFFF to accelerate the leaching of PFAAs from unsaturated soils in a highly characterized field test cell. Porous cup suction lysimeters were used to assess the changes in PFAA porewater concentrations as a function of PFAA mass removal from the unsaturated soils, where flushing was intermittently paused to determine ambient PFAA porewater concentrations. Results showed that the fractional decreases in PFAA porewater concentrations during flushing exceeded the fractional decrease in PFAA mass removal from the soil. PFOS porewater concentrations decrease by 76% (with negligible rebound) compared to only a 7.4% decrease in overall PFOS mass removed from the unsaturated zone. Overall, the results observed herein suggest that, when considering soil impacts to groundwater, less stringent soil cleanup criteria than those that consider an equivalent relationship between mass removal and mass discharge may be appropriate. In addition, remedial approaches that remove only a modest fraction of the PFAA soil mass may be protective of underlying groundwater, particularly for perfluorinated sulfonates with at least six carbons.
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Affiliation(s)
- Charles E Schaefer
- CDM Smith, 110 Fieldcrest Avenue, #8, 6th Floor, Edison, New Jersey08837, United States
| | - Graig M Lavorgna
- APTIM Federal Services, 17 Princess Rd, Lawrenceville, New Jersey08648, United States
| | - David R Lippincott
- APTIM Federal Services, 17 Princess Rd, Lawrenceville, New Jersey08648, United States
| | - Dung Nguyen
- CDM Smith, 14432 SE Eastgate Way, # 100, Bellevue, Washington98007, United States
| | - Andre Schaum
- Department of Molecular and Environmental Toxicology, Oregon State University, 1007 Agricultural and Life Science Building, Corvallis, Oregon97331, United States
| | - Christopher P Higgins
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado80401, United States
| | - Jennifer Field
- Department of Molecular and Environmental Toxicology, Oregon State University, 1007 Agricultural and Life Science Building, Corvallis, Oregon97331, United States
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5
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Blue J, Boving T, Tuccillo ME, Koplos J, Rose J, Brooks M, Burden D. Contaminant Back Diffusion from Low-Conductivity Matrices: Case Studies of Remedial Strategies. WATER 2023; 15:1-31. [PMID: 36959915 PMCID: PMC10031503 DOI: 10.3390/w15030570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Recalcitrant groundwater contamination is a common problem at hazardous waste sites worldwide. Groundwater contamination persists despite decades of remediation efforts at many sites because contaminants sorbed or dissolved within low-conductivity zones can back diffuse into high-conductivity zones, and therefore act as a continuing source of contamination to flowing groundwater. A review of the available literature on remediation of plume persistence due to back diffusion was conducted, and four sites were selected as case studies. Remediation at the sites included pump and treat, enhanced bioremediation, and thermal treatment. Our review highlights that a relatively small number of sites have been studied in sufficient detail to fully evaluate remediation of back diffusion; however, three general conclusions can be made based on the review. First, it is difficult to assess the significance of back diffusion without sufficient data to distinguish between multiple factors contributing to contaminant rebound and plume persistence. Second, high-resolution vertical samples are decidedly valuable for back diffusion assessment but are generally lacking in post-treatment assessments. Third, complete contaminant mass removal from back diffusion sources may not always be possible. Partial contaminant mass removal may nonetheless have potential benefits, similar to partial mass removal from primary DNAPL source zones.
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Affiliation(s)
- Julie Blue
- Eastern Research Group, Concord, MA 01742, USA
| | - Thomas Boving
- Department Geosciences/Department Civil and Environmental Engineering, University of Rhode Island, Kingston, RI 02881, USA
| | | | | | | | - Michael Brooks
- U.S. Environmental Protection Agency, Ada, OK 74820, USA
| | - David Burden
- U.S. Environmental Protection Agency, Ada, OK 74820, USA
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6
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Stewart LD, Chambon JC, Widdowson MA, Kavanaugh MC. Upscaled modeling of complex DNAPL dissolution. JOURNAL OF CONTAMINANT HYDROLOGY 2022; 244:103920. [PMID: 34798507 DOI: 10.1016/j.jconhyd.2021.103920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 09/20/2021] [Accepted: 11/06/2021] [Indexed: 06/13/2023]
Abstract
A straightforward, upscaled DNAPL mass dissolution model is developed using relatively simple input consisting of characteristic dimensions and saturations of a DNAPL accumulation. Multiple accumulations are aggregated into a single source zone volume. Physically, the dissolution process is a combination of flow through the mass (advective component) and flow around the mass (dispersive component). The contribution of each component is based on initial characteristic length scales and the average initial saturation. Changes over time with the depletion of mass are captured with a changing relative permeability and a power law relationship for the fraction of initial mass remaining. The utility of the upscaled process model is demonstrated with data from three studies: numerical simulation of multiple pools, two-dimensional test cell experiments with mixed architecture and with heterogeneous soil, and a controlled field study of multicomponent DNAPL release and depletion. Use of the model successfully reproduced the observed multistage mass discharge in each study and illuminated the governing processes. The power law exponent was relatively constant for the various conditions and relative permeability changes were integral to the success. The numerical and experimental studies were run to complete mass depletion which the upscaled model matched. The input parameters are minimal and are found in typical DNAPL source zone characterization data.
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Affiliation(s)
- Lloyd D Stewart
- Praxis Environmental Technologies, Inc., 1440 Rollins Road, Burlingame, CA 94010, United States.
| | - Julie C Chambon
- Geosyntec Consultants, Inc., 1111 Broadway Street 6th Floor, Oakland, CA 94607, United States
| | - Mark A Widdowson
- The Charles E. Via, Jr. Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA 24061-0105, United States
| | - Michael C Kavanaugh
- Geosyntec Consultants, Inc., 1111 Broadway Street 6th Floor, Oakland, CA 94607, United States
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7
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Cheng Y, Zhu J. Significance of Mass–Concentration Relation on the Contaminant Source Depletion in the Nonaqueous Phase Liquid (NAPL) Contaminated Zone. Transp Porous Media 2021. [DOI: 10.1007/s11242-021-01567-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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8
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Verardo E, Atteia O, Rouvreau L, Siade A, Prommer H. Identifying remedial solutions through optimal bioremediation design under real-world field conditions. JOURNAL OF CONTAMINANT HYDROLOGY 2021; 237:103751. [PMID: 33360418 DOI: 10.1016/j.jconhyd.2020.103751] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 11/18/2020] [Accepted: 11/28/2020] [Indexed: 06/12/2023]
Abstract
Over more than a century of intense industrial production and associated accidental release, petroleum products (e.g., gasoline, diesel, fuel oil) have contaminated a significant portion of the world's groundwater resources. Groundwater remediation is generally a complex task, especially where aquifers and the associated contaminant distribution are highly heterogeneous. The ability to predict the efficiency of such remediation is of crucial importance, as the costs are strongly linked to the treatment design and duration. In this study, a coupled simulation-optimization (S/O) framework, consisting of a process-based reactive transport simulation model linked with particle swarm optimization (PSO) was developed. It was subsequently applied for the design of a real-world in situ bio-treatment of a BTEX contaminated aquifer in France. In the application, the optimization framework was used to simultaneously determine optimal well locations and their optimal injection rates, both constituting key elements of the enhanced biodegradation design problem. The optimization of the treatment efficiency was examined in terms of three different regulatory objectives, (1) minimization of the residual NAPL mass of the key contaminant, i.e., benzene, in the source zone, (2) reduction of the maximum concentration of benzene in groundwater, and (3) minimization of the time required to reduce the benzene concentration in groundwater to below a threshold value. Our analysis of potential, optimal remediation strategies showed that: (i) the complexity of the biodegradation behavior at real sites may favor very different remediation options as a result of varying remediation targets, (ii) the long term behavior of the contaminants after the end of the active treatment period, which is often neglected, showed to have a significant influence on remediation design that requires increased attention, (iii) PSO has shown to be a very efficient algorithm in the context of the present study. The insights that can be gained from such a framework will provide decision support to select the most suitable remediation strategy while facing different regulatory objectives.
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Affiliation(s)
- E Verardo
- ENSEGID, EA4592 G&E, 1 allée Daguin, 33607 Pessac, France
| | - O Atteia
- ENSEGID, EA4592 G&E, 1 allée Daguin, 33607 Pessac, France
| | - L Rouvreau
- BRGM, 3 avenue Claude-Guillemin, 45060 Orléans, France
| | - A Siade
- CSIRO Land and Water, Private Bag No. 5, Wembley, WA 6913, Australia; School of Earth Sciences, University of Western Australia, 35 Stirling Hwy, Nedlands, WA 6009, Australia
| | - H Prommer
- CSIRO Land and Water, Private Bag No. 5, Wembley, WA 6913, Australia; School of Earth Sciences, University of Western Australia, 35 Stirling Hwy, Nedlands, WA 6009, Australia.
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9
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Guo Z, Russo AE, DiFilippo EL, Zhang Z, Zheng C, Brusseau ML. Mathematical modeling of organic liquid dissolution in heterogeneous source zones. JOURNAL OF CONTAMINANT HYDROLOGY 2020; 235:103716. [PMID: 32977295 PMCID: PMC7704655 DOI: 10.1016/j.jconhyd.2020.103716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Revised: 09/13/2020] [Accepted: 09/14/2020] [Indexed: 06/11/2023]
Abstract
A simple one-dimensional heterogeneous-source model was used to simulate dissolution of organic liquid that was non-uniformly distributed in physically heterogeneous porous media. The permeability field was depicted as a pseudo-homogeneous medium. The source zone was discretized into multiple domains representing different organic-liquid configurations and hydraulic accessibilities, each with a different representative upscaled mass transfer rate coefficient that is temporally variable. This simplified approach represents a system where minimal information is available regarding system heterogeneities. All factors that influence dissolution were incorporated into the calibrated mass transfer terms. The mass transfer terms were calibrated for each zone separately. The one-dimensional, heterogeneous-source model adequately simulated the multi-stage dissolution behavior observed for column-scale systems that were packed with different natural soils, as well as for flow-cell systems wherein the source zone consisted of both a residual zone and pool. The results indicate that the model adequately simulated the presence of multiple organic-liquid zones in porous media with different configurations and hydraulic accessibilities, which accounts for the non-ideal dissolution behavior observed. The calibrated mass transfer terms for each source type were consistent with those obtained for systems that contained only one of either source type.
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Affiliation(s)
- Zhilin Guo
- State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
| | - Ann E Russo
- Environmental Science, University of Arizona, 429 Shantz Building, Tucson, AZ 85721, United States
| | - Erica L DiFilippo
- Hydrology and Atmospheric Sciences, University of Arizona, John W. Harshbarger Building, Tucson, AZ 85721, United States
| | - Zhihui Zhang
- Environmental Science, University of Arizona, 429 Shantz Building, Tucson, AZ 85721, United States
| | - Chunmiao Zheng
- State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Mark L Brusseau
- Environmental Science, University of Arizona, 429 Shantz Building, Tucson, AZ 85721, United States; Hydrology and Atmospheric Sciences, University of Arizona, John W. Harshbarger Building, Tucson, AZ 85721, United States.
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10
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Engelmann C, Händel F, Binder M, Yadav PK, Dietrich P, Liedl R, Walther M. The fate of DNAPL contaminants in non-consolidated subsurface systems - Discussion on the relevance of effective source zone geometries for plume propagation. JOURNAL OF HAZARDOUS MATERIALS 2019; 375:233-240. [PMID: 31075551 DOI: 10.1016/j.jhazmat.2019.04.083] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 04/25/2019] [Accepted: 04/26/2019] [Indexed: 06/09/2023]
Abstract
Dense non-aqueous phase liquids, i.e., DNAPLs and the evolving contaminant plumes in aquifers provide significant potential to pose hazards affecting both environment and human health. Therefore, a proper assessment of contaminant spreading within the subsurface is critical. This includes a sufficient characterization of governing parameters describing both the subsurface and the contaminant itself. Thereby, knowledge on the contaminant source zone and especially the source zone geometry, i.e., SZG is critically required, yet very uncertain. This study identifies current limitations and open research questions in the formation and shape determination of source zone geometry, as well as its relevance for contaminant plumes. Our literature review reveals that existing characterization methods are subject to data interpretation uncertainties, while the application of these methods on field scale is limited by technical demands and accompanied efforts. In a next step, methods to implement increased source zone information into calculation methods are discussed. By means of an exemplary application of selected assessment tools, i.e., plume response models, results clearly proof the relevance of SZGs for site assessment. However, existing plume response models consider over-simplified geometries that may compromise their suitability. Our findings identify the demand for improved characterization of complex SZGs and the need to better evaluate the dependency of DNAPL migration on system properties and external influences. With emphasized knowledge on the most relevant SZG features, the delineation of "effective" SZGs allowing for straightforward implementation into plume response models and an adaption of the latter to incorporate more information on SZGs should be possible.
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Affiliation(s)
- Christian Engelmann
- Technische Universität Dresden, Department of Environmental Sciences, Institute of Groundwater Management, Bergstraße 66, 01062 Dresden, Germany; Department Environmental Informatics, Helmholtz-Centre for Environmental Research - UFZ, Permoserstraße 15, 04318 Leipzig, Germany.
| | - Falk Händel
- Technische Universität Dresden, Department of Environmental Sciences, Institute of Groundwater Management, Bergstraße 66, 01062 Dresden, Germany; Department Monitoring and Exploration Technologies, Helmholtz-Centre for Environmental Research - UFZ, Permoserstraße 15, 04318 Leipzig, Germany.
| | - Martin Binder
- Technische Universität Dresden, Department of Environmental Sciences, Institute of Groundwater Management, Bergstraße 66, 01062 Dresden, Germany; Department Environmental Informatics, Helmholtz-Centre for Environmental Research - UFZ, Permoserstraße 15, 04318 Leipzig, Germany.
| | - Prabhas Kumar Yadav
- Technische Universität Dresden, Department of Environmental Sciences, Institute of Groundwater Management, Bergstraße 66, 01062 Dresden, Germany; Manipal University Jaipur, Department of Civil Engineering at School of Civil and Chemical Engineering, Jaipur, India.
| | - Peter Dietrich
- Department Monitoring and Exploration Technologies, Helmholtz-Centre for Environmental Research - UFZ, Permoserstraße 15, 04318 Leipzig, Germany; Center of Applied Geoscience, University of Tübingen, Sigwartstraße 10, 72076 Tübingen, Germany.
| | - Rudolf Liedl
- Technische Universität Dresden, Department of Environmental Sciences, Institute of Groundwater Management, Bergstraße 66, 01062 Dresden, Germany.
| | - Marc Walther
- Technische Universität Dresden, Department of Environmental Sciences, Institute of Groundwater Management, Bergstraße 66, 01062 Dresden, Germany; Department Environmental Informatics, Helmholtz-Centre for Environmental Research - UFZ, Permoserstraße 15, 04318 Leipzig, Germany.
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11
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Guo Z, Fogg GE, Brusseau ML, LaBolle EM, Lopez J. Modeling groundwater contaminant transport in the presence of large heterogeneity: A case study comparing MT3D and RWhet. HYDROGEOLOGY JOURNAL 2019; 27:1363-1371. [PMID: 31933539 PMCID: PMC6957266 DOI: 10.1007/s10040-019-01938-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
A case study is presented that implements two numerical models for simulating a 30-year PAT operation conducted at a large contaminated site for which high-resolution data sets are available. A Markov chain based stochastic method is used to conditionally generate the realizations with random distribution of heterogeneity for the Tucson International Airport Area (TIAA) federal Superfund site. The fields were conditioned to data collected for 245 boreholes drilled at the site. Both MT3DMS and the advanced random walk particle method (RWhet) were used to simulate the PAT-based mass removal process. The results show that both MT3DMS and RWhet represent the measured data reasonably, with Root Mean Square Error (RMSE) less than 0.03. The use of fine grids and the total-variation-diminishing method (TVD) limited the effects of numerical dispersion for MT3DMS. However, the effects of numerical dispersion were observed when compared to the simulations produced with RWhet using a larger number of particles, which provided more accurate results with RMSE diminishing from 0.027 to 0.024 to 0.020 for simulations with 1, 20, and 50 particles. The computational time increased with more particles used in the model, but was still much less than the time required for MT3DMS, which is an advantage of RWhet. By showing the results using both methods, this study provides guidance for simulating long-term PAT systems. This work will lead to improve understanding of contaminant transport and plume persistence, and in turn will enhance site characterization and site management for contaminated sites with large plumes.
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Affiliation(s)
- Zhilin Guo
- Land, Air, and Water Resources, University of California, Davis, 1 Shields Ave, Davis, CA, 95616
- Corresponding author: Department of Land, Air, and Water Resources, University of California, Davis, CA 95616, United States. (Zhilin Guo)
| | - Graham E. Fogg
- Land, Air, and Water Resources, University of California, Davis, 1 Shields Ave, Davis, CA, 95616
| | - Mark L. Brusseau
- Soil, Water and Environmental Science Department, University of Arizona, 429 Shantz Bldg., Tucson, AZ 85721
| | - Eric M. LaBolle
- Land, Air, and Water Resources, University of California, Davis, 1 Shields Ave, Davis, CA, 95616
| | - Jose Lopez
- Land, Air, and Water Resources, University of California, Davis, 1 Shields Ave, Davis, CA, 95616
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12
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Guo Z, Brusseau ML, Fogg GE. Determining the long-term operational performance of pump and treat and the possibility of closure for a large TCE plume. JOURNAL OF HAZARDOUS MATERIALS 2019; 365:796-803. [PMID: 30476803 PMCID: PMC6320714 DOI: 10.1016/j.jhazmat.2018.11.057] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Revised: 10/20/2018] [Accepted: 11/15/2018] [Indexed: 05/11/2023]
Abstract
The purpose of this study is to evaluate the impact of heterogeneity on the long-term performance of a large pump-and-treat (PAT) system that has been in operation for 30 years at a site located in Tucson, AZ. A 3D numerical model was developed. Three different concentrations were examined: composite concentration in the influent to the treatment plant, resident concentration in the aquifer, and concentration for downgradient boundary discharge. The time scales needed for concentrations measured in these ways to reach the Maximum Contaminant Levels (MCLs) are significantly different, with ∼125 years required for treatment-plant influent compared to ∼225 years for downgradient boundary discharge and >>227 years (total simulated time) for the resident concentration in the aquifer. These large time scales, compared to 36 years for a hypothetical homogeneous system, demonstrate the significant impacts of permeability heterogeneity on remediation at this site. The possibility of closure of the site was investigated by examining the mass discharge from the site boundary and the concentration rebound after simulating shutdown of the PAT system. The results of this study provide insight on evaluation of closure potential for large, complex contamination sites and a reference on selecting performance metrics for site management.
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Affiliation(s)
- Zhilin Guo
- Land, Air, and Water Resources, University of California, Davis, 1 Shields Ave, Davis, CA, 95616, United States.
| | - Mark L Brusseau
- Soil, Water and Environmental Science Department, University of Arizona, 429 Shantz Bldg., Tucson, AZ, 85721, United States
| | - Graham E Fogg
- Land, Air, and Water Resources, University of California, Davis, 1 Shields Ave, Davis, CA, 95616, United States
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Brooks MC, Wood AL, Cho J, Williams CAP, Brandon W, Annable MD. Source strength functions from long-term monitoring data and spatially distributed mass discharge measurements. JOURNAL OF CONTAMINANT HYDROLOGY 2018; 219:28-39. [PMID: 30361116 PMCID: PMC7390023 DOI: 10.1016/j.jconhyd.2018.09.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 08/16/2018] [Accepted: 09/19/2018] [Indexed: 06/08/2023]
Abstract
Source strength functions (SSF), defined as contaminant mass discharge or flux-averaged concentration from dense nonaqueous phase liquid (DNAPL) source zones as a function of time, provide a quantitative model of DNAPL source-zone behavior. Such information is useful for calibration of screening-level models to assist with site management decisions. We investigate the use of historic data collected during long-term monitoring (LTM) activities at a site in Rhode Island to predict the SSF based on temporal mass discharge measurements at a fixed location, as well as SSF estimation using mass discharge measurements at a fixed time from three spatially distributed control planes. Mass discharge based on LTM data decreased from ~300 g/day in 1996 to ~70 g/day in 2012 at a control plane downgradient of the suspected DNAPL source zone, and indicates an overall decline of ~80% in 16 years. These measurements were compared to current mass discharge measurements across three spatially distributed control planes. Results indicate that mass discharge increased in the downgradient direction, and was ~6 g/day, ~37 g/day, and ~400 g/day at near, intermediate, and far distances from the suspected source zone, respectively. This behavior was expected given the decreasing trend observed in the LTM data at a fixed location. These two data sets were compared using travel time as a means to plot the data sets on a common axis. The similarity between the two data sets gives greater confidence to the use of this combined data set for site-specific SSF estimation relative to either the sole use of LTM or spatially distributed data sets.
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Affiliation(s)
- Michael C Brooks
- National Risk Management Research Laboratory, U.S. Environmental Protection Agency, Ada, OK 74820, United States.
| | - A Lynn Wood
- Retired, National Risk Management Research Laboratory, U.S. Environmental Protection Agency, Ada, OK 74820, United States
| | - Jaehyun Cho
- Interdisciplinary Program in Hydrologic Sciences, Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL 32611, United States
| | - Christine A P Williams
- Federal Facility Superfund Section, U.S. Environmental Protection Agency, Boston, MA 02109, United States
| | - William Brandon
- Federal Facility Superfund Section, U.S. Environmental Protection Agency, Boston, MA 02109, United States
| | - Michael D Annable
- Interdisciplinary Program in Hydrologic Sciences, Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL 32611, United States
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Giraud Q, Gonçalvès J, Paris B, Joubert A, Colombano S, Cazaux D. 3D numerical modelling of a pulsed pumping process of a large DNAPL pool: In situ pilot-scale case study of hexachlorobutadiene in a keyed enclosure. JOURNAL OF CONTAMINANT HYDROLOGY 2018; 214:24-38. [PMID: 29807703 DOI: 10.1016/j.jconhyd.2018.05.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 02/05/2018] [Accepted: 05/16/2018] [Indexed: 06/08/2023]
Abstract
Remediation of dense non-aqueous phase liquids (DNAPLs) represents a challenging issue because of their persistent behaviour in the environment. This pilot-scale study investigates, by means of in situ experiments and numerical modelling, the feasibility of the pulsed pumping process of a large amount of a DNAPL in an alluvial aquifer. The main compound of the DNAPL is hexachlorobutadiene (HCBD), added in 2015 to the persistent organic pollutants list (POP). A low-permeability keyed enclosure was built at the location of the DNAPL source zone in order to isolate a finite volume of soil and a 3-month pulsed pumping process was applied inside the enclosure to exclusively extract the DNAPL. The water/DNAPL interface elevation at both the pumping well and an observation well was recorded. The cumulated pumped volume of DNAPL was also monitored. A total volume of about 20 m3 of pure DNAPL was recovered since no water was extracted during the process. The three-dimensional and multiphase flow simulator TMVOC was used and a conceptual model was elaborated and generated with the pre/post-processing tool mView. Numerical simulations reproduce the pulsed pumping process and show an excellent match between simulated and field data of DNAPL cumulated pumped volume and a reasonable agreement between modelled and observed data for the evolution of the water/DNAPL interface elevations at the two wells. This study offers a new perspective in remediation since DNAPL pumping system optimisation may be performed where a large amount of DNAPL is encountered.
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Affiliation(s)
- Quentin Giraud
- CEREGE, Europôle Méditerranéen de l'Arbois, Avenue Louis Philibert, 13545 Aix-en-Provence, France; INTERA, 90 Avenue Lanessan, 69410 Champagne-au-Mont-d'Or, France.
| | - Julio Gonçalvès
- CEREGE, Europôle Méditerranéen de l'Arbois, Avenue Louis Philibert, 13545 Aix-en-Provence, France
| | - Benoît Paris
- INTERA, 90 Avenue Lanessan, 69410 Champagne-au-Mont-d'Or, France
| | | | | | - David Cazaux
- INOVYN, Avenue de la République, 39500 Tavaux, France
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15
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Brusseau ML, Guo Z. The integrated contaminant elution and tracer test toolkit, ICET 3, for improved characterization of mass transfer, attenuation, and mass removal. JOURNAL OF CONTAMINANT HYDROLOGY 2018; 208:17-26. [PMID: 29198786 PMCID: PMC5767144 DOI: 10.1016/j.jconhyd.2017.11.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 11/17/2017] [Accepted: 11/21/2017] [Indexed: 05/31/2023]
Abstract
It is evident based on historical data that groundwater contaminant plumes persist at many sites, requiring costly long-term management. High-resolution site-characterization methods are needed to support accurate risk assessments and to select, design, and operate effective remediation operations. Most subsurface characterization methods are generally limited in their ability to provide unambiguous, real-time delineation of specific processes affecting mass-transfer, transformation, and mass removal, and accurate estimation of associated rates. An integrated contaminant elution and tracer test toolkit, comprising a set of local-scale groundwater extraction-and injection tests, was developed to ameliorate the primary limitations associated with standard characterization methods. The test employs extended groundwater extraction to stress the system and induce hydraulic and concentration gradients. Clean water can be injected, which removes the resident aqueous contaminant mass present in the higher-permeability zones and isolates the test zone from the surrounding plume. This ensures that the concentrations and fluxes measured within the isolated area are directly and predominantly influenced by the local mass-transfer and transformation processes controlling mass removal. A suite of standard and novel tracers can be used to delineate specific mass-transfer and attenuation processes that are active at a given site, and to quantify the associated mass-transfer and transformation rates. The conceptual basis for the test is first presented, followed by an illustrative application based on simulations produced with a 3-D mathematical model and a brief case study application.
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Affiliation(s)
- Mark L Brusseau
- Soil, Water and Environmental Science Department, University of Arizona, 429 Shantz Bldg., Tucson, AZ 85721, United States; Hydrology and Atmospheric Sciences Department, School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Bldg., Tucson, AZ 85721, United States.
| | - Zhilin Guo
- Soil, Water and Environmental Science Department, University of Arizona, 429 Shantz Bldg., Tucson, AZ 85721, United States
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16
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Guo Z, Brusseau ML. The Impact of Well-Field Configuration on Contaminant Mass Removal and Plume Persistence for Homogeneous versus Layered Systems. HYDROLOGICAL PROCESSES 2017; 31:4748-4756. [PMID: 29755199 PMCID: PMC5944865 DOI: 10.1002/hyp.11393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A three-dimensional numerical model was used to simulate the impact of different well-field configurations on pump-and-treat mass removal efficiency for large groundwater contaminant plumes residing in homogeneous and layered domains. Four well-field configurations were tested, Longitudinal, Distributed, Downgradient, and natural gradient (with no extraction wells). The reductions in contaminant mass discharge (CMDR) as a function of mass removal (MR) were characterized to assess remediation efficiency. Systems whose CDMR-MR profiles are below the 1:1 relationship curve are associated with more efficient well-field configurations. For simulations conducted with the homogeneous domain, the CMDR-MR curves shift leftward, from convex-downward profiles for natural gradient and Longitudinal to first-order behaviour for Distributed, and further leftward to a sigmoidal profile for the Downgradient well-field configuration. These results reveal the maximum potential impacts of well-field configuration on mass-removal behaviour, which is attributed to mass-transfer constraints associated with regions of low flow. In contrast, for the simulations conducted with the layered domain, the CMDR-MR relationships for the different well-field configurations exhibit convex-upward profiles. The nonideal mass-removal behaviour in this case is influenced by both well-field configuration and back diffusion associated with low-permeability units.
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Affiliation(s)
- Zhilin Guo
- Soil, Water and Environmental Science Department, School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Bldg. Tucson, AZ 85721
| | - Mark L. Brusseau
- Hydrology and Water Resources Department, School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Bldg. Tucson, AZ 85721
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17
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Mateas DJ, Tick GR, Carroll KC. In situ stabilization of NAPL contaminant source-zones as a remediation technique to reduce mass discharge and flux to groundwater. JOURNAL OF CONTAMINANT HYDROLOGY 2017; 204:40-56. [PMID: 28780996 DOI: 10.1016/j.jconhyd.2017.07.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Revised: 05/16/2017] [Accepted: 07/24/2017] [Indexed: 06/07/2023]
Abstract
Widely used flushing and in-situ destruction based remediation techniques (i.e. pump-and treat, enhanced-solubilization, and chemical oxidation/reduction) for sites contaminated by nonaqueous phase liquid (NAPL) contaminant sources have been shown to be ineffective at complete mass removal and reducing aqueous-phase contaminant of concern (COC) concentrations to levels suitable for site closure. A remediation method was developed to reduce the aqueous solubility and mass-flux of COCs within NAPL through the in-situ creation of a NAPL mixture source-zone. In contrast to remediation techniques that rely on the rapid removal of contaminant mass, this technique relies on the stabilization of difficult-to-access NAPL sources to reduce COC mass flux to groundwater. A specific amount (volume) of relatively insoluble n-hexadecane (HEXDEC) or vegetable oil (VO) was injected into a trichloroethene (TCE) contaminant source-zone through a bench-scale flow cell port (i.e. well) to form a NAPL mixture of targeted mole fraction (TCE:HEXDEC or TCE:VO). NAPL-aqueous phase batch tests were conducted prior to the flow-cell experiments to evaluate the effects of various NAPL mixture ratios on equilibrium aqueous-phase concentrations of TCE to design optimal NAPL (HEXDEC or VO) injection volumes for the flow-cell experiments. The NAPL-stabilization flow-cell experiments initiated and sustained significant reductions in COC concentration and mass flux due to a combination of both reduced relative permeability (increased NAPL-saturation) and via modification of NAPL composition (decreased TCE mole fraction). Variations in remediation performance (i.e. impacts on TCE concentration and mass flux reduction) between the different HEXDEC injection volumes were relatively minor, and therefore inconsistent with Raoult's Law predictions. This phenomenon likely resulted from non-uniform mixing of the injected HEXDEC with TCE in the source-zone. VO injection caused TCE concentrations and mass-flux to decrease more rapidly than with HEXDEC injections. This phenomenon occurred because the injected VO was observed to mix more uniformly with TCE in the source-zone due to a lower mobilization potential. The relative lower density differences (buoyancy effects) between VO and the flushing solution (water) was the primary factor contributing to the lower mobilization potential for VO. Overall, this study indicated that the delivery of HEXDEC or VO into the toxic TCE source-zone was effective in significantly reducing contaminant aqueous-phase concentration and mass-flux. However, the effectiveness of this in-situ NAPL stabilization technique depends on source delivery, uniform mixing of amendment, and that the amendment remains immobilized within and around the NAPL contaminant source.
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Affiliation(s)
- Douglas J Mateas
- Department of Geological Sciences, The University of Alabama, Tuscaloosa, AL 35487, United States
| | - Geoffrey R Tick
- Department of Geological Sciences, The University of Alabama, Tuscaloosa, AL 35487, United States.
| | - Kenneth C Carroll
- Department of Plant and Environmental Sciences, New Mexico State University, Las Cruces, NM 88003, United States
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18
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Guo Z, Brusseau ML. The impact of well-field configuration and permeability heterogeneity on contaminant mass removal and plume persistence. JOURNAL OF HAZARDOUS MATERIALS 2017; 333:109-115. [PMID: 28342351 PMCID: PMC5426908 DOI: 10.1016/j.jhazmat.2017.03.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 02/10/2017] [Accepted: 03/05/2017] [Indexed: 05/03/2023]
Abstract
The purpose of this study is to investigate the effects of well-field hydraulics and permeability heterogeneity on mass-removal efficiency for systems comprising large groundwater contaminant plumes. A three-dimensional (3D) numerical model was used to simulate the impact of different well-field configurations on pump-and-treat mass removal for heterogeneous domains. The relationship between reduction in contaminant mass discharge (CMDR) and mass removal (MR) was used as the metric to examine remediation efficiency. The impacts of well-field configuration on mass removal behavior are attributed to mass-transfer constraints related to regions of low flow associated with the well field, which can be muted by the influence of permeability heterogeneity. These impacts are reflected in the associated CMDR-MR profiles. Systems whose CDMR-MR profiles are below the 1:1 relationship line are associated with more efficient well-field configurations. The impact of domain heterogeneity on mass-removal effectiveness was investigated in terms of both variance and correlation scale of the random permeability distributions and indexed by the CMDR-MR relationship. Data collected from pump-and-treat operations conducted in a section of the Tucson International Airport Area (TIAA) federal Superfund site were used as a case study. The comparison between simulated and measured site data supports the general validity of the numerical model, and results from the case study are consistent with the conclusions of the theoretical study. These results illustrate that the CMDR-MR relationship can be an effective way to quantify the impacts of different factors on mass-removal efficiency.
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Affiliation(s)
- Zhilin Guo
- Soil, Water and Environmental Science Department, School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Bldg., Tucson, AZ 85721, United States
| | - Mark L Brusseau
- Soil, Water and Environmental Science Department, School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Bldg., Tucson, AZ 85721, United States; Hydrology and Atmospheric Sciences Department, School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Bldg., Tucson, AZ 85721, United States.
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19
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Guo Z, Brusseau ML. Modified Well-Field Configurations for Improved Performance of Contaminant Elution and Tracer Tests. WATER, AIR, AND SOIL POLLUTION 2017; 228:261. [PMID: 29755148 PMCID: PMC5944624 DOI: 10.1007/s11270-017-3432-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 06/08/2017] [Indexed: 06/01/2023]
Abstract
Contaminant elution and tracer (CET) tests are one method for characterizing the impact of mass transfer, transformation, and other attenuation processes on contaminant transport and mass removal for subsurface systems. The purpose of the work reported herein is to explore specific well-field configurations for improving CET tests by reducing the influence of preferential flow and surrounding-plume effects. Three injection-extraction well configurations were tested for different domain conditions using a three-dimensional numerical model. The three configurations were the traditional configuration with a single pair of injection-extraction wells, modified configuration I with one extraction well located between two injection wells, and modified configuration II with two pairs of injection-extraction couplets (one nested within the other). Elution curves for resident contaminant and breakthrough curves from simulated tracer tests were examined for specific landmarks such as the presence and extent of steady-state (relatively high concentrations) and asymptotic (asymptotic decrease to low concentrations) phases, as well as distinct changes in slope. Temporal-moment analysis of the breakthrough curves was conducted to evaluate mass recovery. Effective diffusion coefficients were obtained by fitting selected functions to the elution curves. Based on simulation results for a homogeneous domain, full isolation of the inner extraction well from the surrounding plume was obtained for the modified configuration II, whereas the extraction wells are impacted by the surrounding plume for the other two configurations. Therefore, configuration II was used for additional simulations conducted with layered and heterogeneous domains. Tracer-test simulations for homogeneous and layered domains indicate 100% mass recovery for the inner extraction well. For the heterogeneous domain, decreasing the distance between the inner injection-extraction well couplet and adjusting the pumping-rate distribution between the two extraction wells increased the mass recovery from 69% to 99%.
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Affiliation(s)
- Zhilin Guo
- Soil, Water and Environmental Science Department, School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Bldg. Tucson, AZ 85721
| | - Mark L. Brusseau
- Soil, Water and Environmental Science Department, School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Bldg. Tucson, AZ 85721
- Hydrology and Water Resources Department, School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Bldg. Tucson, AZ 85721
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20
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Zhu J, Sun D. Significance of groundwater flux on contaminant concentration and mass discharge in the nonaqueous phase liquid (NAPL) contaminated zone. JOURNAL OF CONTAMINANT HYDROLOGY 2016; 192:158-164. [PMID: 27500747 DOI: 10.1016/j.jconhyd.2016.08.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2016] [Revised: 06/13/2016] [Accepted: 08/01/2016] [Indexed: 06/06/2023]
Abstract
Groundwater flowing through residual nonaqueous phase liquid (NAPL) source zone will cause NAPL dissolution and generate large contaminant plume. The use of contaminant mass discharge (CMD) measurements in addition to NAPL aqueous phase concentration to characterize site conditions and assess remediation performance is becoming popular. In this study, we developed new and generic numerical models to investigate the significance of groundwater flux temporal variations on the NAPL source dynamics. The developed models can accommodate any temporal variations of groundwater flux in the source zone. We examined the various features of groundwater flux using a few selected functional forms of linear increase/decrease, gradual smooth increase/decrease, and periodic fluctuations with a general trend. Groundwater flux temporal variations have more pronounced effects on the contaminant mass discharge dynamics than the aqueous concentration. If the groundwater flux initially increases, then the reduction in contaminant mass discharge (CMDR) vs. NAPL mass reduction (MR) relationship is mainly downward concave. If the groundwater flux initially decreases, then CMDR vs. MR relationship is mainly upward convex. If the groundwater flux variations are periodic, the CMDR vs. MR relationship tends to also have periodic variations ranging from upward convex to downward concave. Eventually, however, the CMDR vs. MR relationship approaches 1:1 when majority of the NAPL mass becomes depleted.
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Affiliation(s)
- Jianting Zhu
- Department of Civil and Architectural Engineering, University of Wyoming, Laramie, WY 82071, USA.
| | - Dongmin Sun
- Environmental Science Program, University of Houston Clear Lake, Houston, TX 77058, USA
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21
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Mainhagu J, Brusseau ML. Estimating initial contaminant mass based on fitting mass-depletion functions to contaminant mass discharge data: Testing method efficacy with SVE operations data. JOURNAL OF CONTAMINANT HYDROLOGY 2016; 192:152-157. [PMID: 27494132 DOI: 10.1016/j.jconhyd.2016.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Revised: 06/28/2016] [Accepted: 07/09/2016] [Indexed: 06/06/2023]
Abstract
The mass of contaminant present at a site, particularly in the source zones, is one of the key parameters for assessing the risk posed by contaminated sites, and for setting and evaluating remediation goals and objectives. This quantity is rarely known and is challenging to estimate accurately. This work investigated the efficacy of fitting mass-depletion functions to temporal contaminant mass discharge (CMD) data as a means of estimating initial mass. Two common mass-depletion functions, exponential and power functions, were applied to historic soil vapor extraction (SVE) CMD data collected from 11 contaminated sites for which the SVE operations are considered to be at or close to essentially complete mass removal. The functions were applied to the entire available data set for each site, as well as to the early-time data (the initial 1/3 of the data available). Additionally, a complete differential-time analysis was conducted. The latter two analyses were conducted to investigate the impact of limited data on method performance, given that the primary mode of application would be to use the method during the early stages of a remediation effort. The estimated initial masses were compared to the total masses removed for the SVE operations. The mass estimates obtained from application to the full data sets were reasonably similar to the measured masses removed for both functions (13 and 15% mean error). The use of the early-time data resulted in a minimally higher variation for the exponential function (17%) but a much higher error (51%) for the power function. These results suggest that the method can produce reasonable estimates of initial mass useful for planning and assessing remediation efforts.
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Affiliation(s)
- J Mainhagu
- Soil, Water and Environmental Science Department, School of Earth and Environmental Sciences, University of Arizona, Tucson, AZ 85721, United States
| | - M L Brusseau
- Soil, Water and Environmental Science Department, School of Earth and Environmental Sciences, University of Arizona, Tucson, AZ 85721, United States; Hydrology and Water Resources Department, School of Earth and Environmental Sciences, University of Arizona, Tucson, AZ 85721, United States.
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22
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Brusseau ML, Mainhagu J, Morrison C, Carroll KC. The vapor-phase multi-stage CMD test for characterizing contaminant mass discharge associated with VOC sources in the vadose zone: Application to three sites in different lifecycle stages of SVE operations. JOURNAL OF CONTAMINANT HYDROLOGY 2015; 179:55-64. [PMID: 26047819 PMCID: PMC4520789 DOI: 10.1016/j.jconhyd.2015.05.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Revised: 04/10/2015] [Accepted: 05/17/2015] [Indexed: 06/01/2023]
Abstract
Vapor-phase multi-stage contaminant mass discharge (CMD) tests were conducted at three field sites to measure mass discharge associated with contaminant sources located in the vadose zone. The three sites represent the three primary stages of the soil vapor extraction (SVE) operations lifecycle-pre/initial-SVE, mid-lifecycle, and near-closure. A CMD of 32g/d was obtained for a site at which soil vapor SVE has been in operation for approximately 6years, and for which mass removal is currently in the asymptotic stage. The contaminant removal behavior exhibited for the vapor extractions conducted at this site suggests that there is unlikely to be a significant mass of non-vapor-phase contaminant (e.g., DNAPL, sorbed phase) remaining in the advective domains, and that most remaining mass is likely located in poorly accessible domains. Given the conditions for this site, this remaining mass is hypothesized to be associated with the low-permeability (and higher water saturation) region in the vicinity of the saturated zone and capillary fringe. A CMD of 25g/d was obtained for a site wherein SVE has been in operation for several years but concentrations and mass-removal rates are still relatively high. A CMD of 270g/d was obtained for a site for which there were no prior SVE operations. The behavior exhibited for the vapor extractions conducted at this site suggest that non-vapor-phase contaminant mass (e.g., DNAPL) may be present in the advective domains. Hence, the asymptotic conditions observed for this site most likely derive from a combination of rate-limited mass transfer from DNAPL (and sorbed) phases present in the advective domain as well as mass residing in lower-permeability ("non-advective") regions. The CMD values obtained from the tests were used in conjunction with a recently developed vapor-discharge tool to evaluate the impact of the measured CMDs on groundwater quality.
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Affiliation(s)
- M L Brusseau
- Soil, Water and Environmental Science Department, School of Earth and Environmental Sciences, University of Arizona, Tucson, AZ 85721, United States; Hydrology and Water Resources Department, School of Earth and Environmental Sciences, University of Arizona, Tucson, AZ 85721, United States.
| | - J Mainhagu
- Soil, Water and Environmental Science Department, School of Earth and Environmental Sciences, University of Arizona, Tucson, AZ 85721, United States
| | - C Morrison
- Soil, Water and Environmental Science Department, School of Earth and Environmental Sciences, University of Arizona, Tucson, AZ 85721, United States
| | - K C Carroll
- Plant and Environmental Sciences Department, New Mexico State University, United States
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Mainhagu J, Morrison C, Brusseau ML. Using vapor phase tomography to measure the spatial distribution of vapor concentrations and flux for vadose-zone VOC sources. JOURNAL OF CONTAMINANT HYDROLOGY 2015; 177-178:54-63. [PMID: 25835545 PMCID: PMC4456264 DOI: 10.1016/j.jconhyd.2015.03.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2014] [Revised: 02/26/2015] [Accepted: 03/08/2015] [Indexed: 05/11/2023]
Abstract
A test was conducted at a chlorinated-solvent contaminated site in Tucson, AZ, to evaluate the effectiveness of vapor-phase tomography (VPT) for characterizing the distribution of volatile organic contaminants (VOC) in the vadose zone. A soil vapor extraction (SVE) system has been in operation at the site since 2007. Vapor concentration and vacuum pressure were measured at four different depths in each of the four monitoring wells surrounding the extraction well. The test provided a 3D characterization of local vapor concentrations under induced-gradient conditions. Permeability data obtained from analysis of borehole logs were used along with pressure and the vapor-concentration data to determine VOC mass flux within the test domain. A region of higher mass flux was identified in the deepest interval of the S-SW section of the domain, indicating the possible location of a zone with greater contaminant mass. These results are consistent with the TCE-concentration distribution obtained from sediment coring conducted at the site. In contrast, the results of a standard soil gas survey did not indicate the presence of a zone with greater contaminant mass. These results indicate that the VPT test provided a robust characterization of VOC concentration and flux distribution at the site.
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Affiliation(s)
- J Mainhagu
- Soil, Water and Environmental Science Department, School of Earth and Environmental Sciences, University of Arizona, Tucson, AZ 85721, United States
| | - C Morrison
- Soil, Water and Environmental Science Department, School of Earth and Environmental Sciences, University of Arizona, Tucson, AZ 85721, United States
| | - M L Brusseau
- Soil, Water and Environmental Science Department, School of Earth and Environmental Sciences, University of Arizona, Tucson, AZ 85721, United States; Hydrology and Water Resources Department, School of Earth and Environmental Sciences, University of Arizona, Tucson, AZ 85721, United States.
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24
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Marble J, Brusseau M, Carroll K, Plaschke M, Fuhrig L, Brinker F. Application of a Persistent Dissolved-phase Reactive Treatment Zone for Mitigation of Mass Discharge from Sources Located in Lower-Permeability Sediments. WATER, AIR, AND SOIL POLLUTION 2014; 225:2198. [PMID: 26300570 PMCID: PMC4540080 DOI: 10.1007/s11270-014-2198-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The purpose of this study is to examine the development and effectiveness of a persistent dissolved-phase treatment zone, created by injecting potassium permanganate solution, for mitigating discharge of contaminant from a source zone located in a relatively deep, low-permeability formation. A localized 1,1-dichloroethene (DCE) source zone comprising dissolved- and sorbed-phase mass is present in lower permeability strata adjacent to a sand/gravel unit in a section of the Tucson International Airport Area (TIAA) Superfund Site. The results of bench-scale studies conducted using core material collected from boreholes drilled at the site indicated that natural oxidant demand was low, which would promote permanganate persistence. The reactive zone was created by injecting a permanganate solution into multiple wells screened across the interface between the lower-permeability and higher-permeability units. The site has been monitored for nine years to characterize the spatial distribution of DCE and permanganate. Permanganate continues to persist at the site, and a substantial and sustained decrease in DCE concentrations in groundwater has occurred after the permanganate injection.. These results demonstrate successful creation of a long-term, dissolved-phase reactive-treatment zone that reduced mass discharge from the source. This project illustrates the application of in-situ chemical oxidation as a persistent dissolved-phase reactive-treatment system for lower-permeability source zones, which appears to effectively mitigate persistent mass discharge into groundwater.
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Affiliation(s)
- J.C. Marble
- Soil, Water and Environmental Science Department, University of Arizona, 429 Shantz Bldg., Tucson, AZ 85721
- Hydrology and Water Resources Department, School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Bldg., Tucson, AZ 85721
| | - M.L. Brusseau
- Soil, Water and Environmental Science Department, University of Arizona, 429 Shantz Bldg., Tucson, AZ 85721
- Hydrology and Water Resources Department, School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Bldg., Tucson, AZ 85721
| | - K.C. Carroll
- Plant & Environmental Sciences Department, New Mexico State University
| | - M. Plaschke
- Conestoga-Rovers and Assoc., Inc., Phoenix, AZ
| | - L. Fuhrig
- Soil, Water and Environmental Science Department, University of Arizona, 429 Shantz Bldg., Tucson, AZ 85721
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Brusseau ML, Guo Z. Assessing contaminant-removal conditions and plume persistence through analysis of data from long-term pump-and-treat operations. JOURNAL OF CONTAMINANT HYDROLOGY 2014; 164:16-24. [PMID: 24914523 PMCID: PMC4117718 DOI: 10.1016/j.jconhyd.2014.05.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 02/24/2014] [Accepted: 05/15/2014] [Indexed: 05/03/2023]
Abstract
Historical groundwater-withdrawal and contaminant-concentration data collected from long-term pump-and-treat operations were analyzed and used to examine contaminant mass discharge (CMD) and mass-removal behavior for multiple sites. Differences in behavior were observed, and these differences were consistent with the nature of contaminant distributions and subsurface properties of the sites. For example, while CMD exhibited a relatively rapid decline during the initial stage of operation for all three sites, the rate of decline varied. The greatest rate was observed for the PGN site, whereas the lowest rate was observed for the MOT site. In addition, the MOT site exhibited the lowest relative reduction in CMD. These results are consistent with the actuality that the MOT site likely contains the greatest proportion of poorly accessible contaminant mass, given that it comprises a combined alluvium and fractured-bedrock system in which solvent and dissolved mass are present directly in the bedrock. The relative contributions of the source zones versus the plumes to total CMD were determined. Constrained contaminant mass removal was observed to influence the plumes for all three sites, and was attributed to a combination of uncontrolled (or imperfectly controlled) sources, back diffusion, and well-field hydraulics. The results presented herein illustrate that detailed analysis of operational pump-and-treat data can be a cost-effective method for providing value-added characterization of contaminated sites.
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Affiliation(s)
- Mark L Brusseau
- School of Earth and Environmental Sciences, University of Arizona, 429 Shantz, Tucson, AZ 85721, United States.
| | - Zhilin Guo
- School of Earth and Environmental Sciences, University of Arizona, 429 Shantz, Tucson, AZ 85721, United States
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Johnston CD, Davis GB, Bastow TP, Woodbury RJ, Rao PSC, Annable MD, Rhodes S. Mass discharge assessment at a brominated DNAPL site: Effects of known DNAPL source mass removal. JOURNAL OF CONTAMINANT HYDROLOGY 2014; 164:100-113. [PMID: 24973505 DOI: 10.1016/j.jconhyd.2014.05.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Revised: 05/20/2014] [Accepted: 05/23/2014] [Indexed: 06/03/2023]
Abstract
Management and closure of contaminated sites is increasingly being proposed on the basis of mass flux of dissolved contaminants in groundwater. Better understanding of the links between source mass removal and contaminant mass fluxes in groundwater would allow greater acceptance of this metric in dealing with contaminated sites. Our objectives here were to show how measurements of the distribution of contaminant mass flux and the overall mass discharge emanating from the source under undisturbed groundwater conditions could be related to the processes and extent of source mass depletion. In addition, these estimates of mass discharge were sought in the application of agreed remediation targets set in terms of pumped groundwater quality from offsite wells. Results are reported from field studies conducted over a 5-year period at a brominated DNAPL (tetrabromoethane, TBA; and tribromoethene, TriBE) site located in suburban Perth, Western Australia. Groundwater fluxes (qw; L(3)/L(2)/T) and mass fluxes (Jc; M/L(2)/T) of dissolved brominated compounds were simultaneously estimated by deploying Passive Flux Meters (PFMs) in wells in a heterogeneous layered aquifer. PFMs were deployed in control plane (CP) wells immediately down-gradient of the source zone, before (2006) and after (2011) 69-85% of the source mass was removed, mainly by groundwater pumping from the source zone. The high-resolution (26-cm depth interval) measures of qw and Jc along the source CP allowed investigation of the DNAPL source-zone architecture and impacts of source mass removal. Comparable estimates of total mass discharge (MD; M/T) across the source zone CP reduced from 104gday(-1) to 24-31gday(-1) (70-77% reductions). Importantly, this mass discharge reduction was consistent with the estimated proportion of source mass remaining at the site (15-31%). That is, a linear relationship between mass discharge and source mass is suggested. The spatial detail of groundwater and mass flux distributions also provided further evidence of the source zone architecture and DNAPL mass depletion processes. This was especially apparent in different mass-depletion rates from distinct parts of the CP. High mass fluxes and groundwater fluxes located near the base of the aquifer dominated in terms of the dissolved mass flux in the profile, although not in terms of concentrations. Reductions observed in Jc and MD were used to better target future remedial efforts. Integration of the observations from the PFM deployments and the source mass depletion provided a basis for establishing flux-based management criteria for the site.
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Affiliation(s)
- C D Johnston
- CSIRO Land and Water, Private Bag No. 5 PO, Wembley, WA 6913, Australia; School of Earth and Environment, University of Western Australia, Nedlands, WA 6009, Australia.
| | - G B Davis
- CSIRO Land and Water, Private Bag No. 5 PO, Wembley, WA 6913, Australia; School of Earth and Environment, University of Western Australia, Nedlands, WA 6009, Australia
| | - T P Bastow
- CSIRO Land and Water, Private Bag No. 5 PO, Wembley, WA 6913, Australia
| | - R J Woodbury
- CSIRO Land and Water, Private Bag No. 5 PO, Wembley, WA 6913, Australia
| | - P S C Rao
- School of Civil Engineering & Agronomy Department, Purdue University, West Lafayette, IN 47907-2051, USA
| | - M D Annable
- Environmental Engineering Sciences, University of Florida, PO Box 116450, Gainesville, FL 32611-6450, USA
| | - S Rhodes
- Rio Tinto, 120 Collins Street, Melbourne, Victoria 3000, Australia
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Matthieu D, Brusseau M, Guo Z, Plaschke M, Carroll K, Brinker F. Persistence of a Groundwater Contaminant Plume after Hydraulic Source Containment at a Chlorinated-Solvent Contaminated Site. GROUND WATER MONITORING & REMEDIATION 2014; 34:23-32. [PMID: 26069436 PMCID: PMC4459649 DOI: 10.1111/gwmr.12077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The objective of this study was to characterize the behavior of a groundwater contaminant (trichloroethene) plume after implementation of a source-containment operation at a site in Arizona. The plume resides in a quasi three-layer system comprising a sand/gravel unit bounded on the top and bottom by relatively thick silty clayey layers. The system was monitored for 60 months beginning at start-up in 2007 to measure the change in contaminant concentrations within the plume, the change in plume area, the mass of contaminant removed, and the integrated contaminant mass discharge. Concentrations of trichloroethene in groundwater pumped from the plume extraction wells have declined significantly over the course of operation, as have concentrations for groundwater sampled from 40 monitoring wells located within the plume. The total contaminant mass discharge associated with operation of the plume extraction wells peaked at 0.23 kg/d, decreased significantly within one year, and thereafter began an asymptotic decline to a current value of approximately 0.03 kg/d. Despite an 87% reduction in contaminant mass and a comparable 87% reduction in contaminant mass discharge for the plume, the spatial area encompassed by the plume has decreased by only approximately 50%. This is much less than would be anticipated based on ideal flushing and mass-removal behavior. Simulations produced with a simplified 3-D numerical model matched reasonably well to the measured data. The results of the study suggest that permeability heterogeneity, back diffusion, hydraulic factors associated with the specific well field system, and residual discharge from the source zone are all contributing to the observed persistence of the plume, as well as the asymptotic behavior currently observed for mass removal and for the reduction in contaminant mass discharge.
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Affiliation(s)
- D.E. Matthieu
- Soil, Water and Environmental Science Department, School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Bldg., Tucson, AZ 85721
| | - M.L. Brusseau
- Soil, Water and Environmental Science Department, School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Bldg., Tucson, AZ 85721
- Hydrology and Water Resources Department, School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Bldg., Tucson, AZ 85721
- Corresponding author,
| | - Z. Guo
- Soil, Water and Environmental Science Department, School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Bldg., Tucson, AZ 85721
| | - M. Plaschke
- Conestoga-Rovers and Assoc., Inc., Phoenix, AZ
| | - K.C. Carroll
- Soil, Water and Environmental Science Department, School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Bldg., Tucson, AZ 85721
- Hydrology and Water Resources Department, School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Bldg., Tucson, AZ 85721
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Lee SS, Kim HM, Lee SH, Yang JH, Koh YE, Lee KK. Evidences of in Situ Remediation from Long Term Monitoring Data at a TCE-contaminated Site, Wonju, Korea. ACTA ACUST UNITED AC 2013. [DOI: 10.7857/jsge.2013.18.6.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Brusseau ML, Carroll KC, Truex MJ, Becker DJ. Characterization and Remediation of Chlorinated Volatile Organic Contaminants in the Vadose Zone: An Overview of Issues and Approaches. VADOSE ZONE JOURNAL : VZJ 2013; 12:10.2136/vzj2012.0137. [PMID: 25383058 PMCID: PMC4222060 DOI: 10.2136/vzj2012.0137] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Indexed: 05/25/2023]
Abstract
Contamination of vadose-zone systems by chlorinated solvents is widespread, and poses significant potential risk to human health through impacts on groundwater quality and vapor intrusion. Soil vapor extraction (SVE) is the presumptive remedy for such contamination, and has been used successfully for innumerable sites. However, SVE operations typically exhibit reduced mass-removal effectiveness at some point due to the impact of poorly accessible contaminant mass and associated mass-transfer limitations. Assessment of SVE performance and closure is currently based on characterizing contaminant mass discharge associated with the vadose-zone source, and its impact on groundwater or vapor intrusion. These issues are addressed in this overview, with a focus on summarizing recent advances in our understanding of the transport, characterization, and remediation of chlorinated solvents in the vadose zone. The evolution of contaminant distribution over time and the associated impacts on remediation efficiency will be discussed, as will the potential impact of persistent sources on groundwater quality and vapor intrusion. In addition, alternative methods for site characterization and remediation will be addressed.
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Affiliation(s)
- Mark L. Brusseau
- School of Earth and Environmental Sciences, University of Arizona, Tucson, AZ
| | | | | | - David J. Becker
- U.S. Army Corps of Engineers, Environmental and Munitions Center of Expertise, Omaha, NE
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Akyol NH, Lee AR, Brusseau ML. Impact of enhanced-flushing reagents and organic-liquid distribution on mass removal and mass-discharge reduction. WATER, AIR, AND SOIL POLLUTION 2013; 224:1731. [PMID: 24563557 PMCID: PMC3930466 DOI: 10.1007/s11270-013-1731-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A series of column and flow-cell experiments was conducted to investigate the impact of non-uniform organic-liquid distribution on the relationship between reductions in contaminant mass discharge and reductions in source zone mass under conditions of enhanced-solubilization flushing. Trichloroethene was used as the model organic liquid, and SDS (sodium dodecyl sulfate) and ethanol were used as representative enhanced-flushing reagents. The results were compared to those of water-flood control experiments. Concentrations of trichloroethene in the effluent exhibited multi-step behavior with time, wherein multiple secondary periods of quasi steady state were observed. This non-ideal behavior was observed for both the water-flood and enhanced-flushing experiments. For all flow-cell experiments, the later stage of mass removal was controlled by the more poorly- accessible mass associated with higher-saturation zones. The profiles relating reductions in contaminant mass discharge and reductions in mass exhibited generally similar behavior for both the water-flood and enhanced-flushing experiments. This indicates that while the rates and magnitudes of mass removal are altered by the presence of a solubilization-reagent solution, the fundamental mass-removal process is not. The profiles obtained for the flow-cell systems differed from those obtained for the column systems, highlighting the impact of source-zone heterogeneity on mass-removal behavior.
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Affiliation(s)
- Nihat Hakan Akyol
- Department of Geological Engineering, University of Kocaeli, TR-41380 Kocaeli, Turkey
- School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Building, Tucson, AZ 85721, United States
| | - Ann Russo Lee
- School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Building, Tucson, AZ 85721, United States
| | - Mark L Brusseau
- School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Building, Tucson, AZ 85721, United States
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Brusseau ML. Use of Historical Pump-and-Treat Data to Enhance Site Characterization and Remediation Performance Assessment. WATER, AIR, AND SOIL POLLUTION 2013; 224:1741. [PMID: 24587562 PMCID: PMC3935331 DOI: 10.1007/s11270-013-1741-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Groundwater withdrawal and contaminant concentration data are routinely collected for pump-and-treat operations conducted at hazardous waste sites. These data sets can be mined to produce a wealth of information to support enhanced site characterization, optimization of remedial system operations, and improved decision making regarding long-term site management and closure. Methods that may be used to analyze and interpret pump-and-treat data to produce such assessments are presented, along with a brief illustration of their application to a site. The results presented herein illustrate that comprehensive analysis of pump-and-treat data is a powerful, cost-effective method for providing higher-resolution, value-added characterization of contaminated sites.
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Affiliation(s)
- Mark L Brusseau
- School of Earth and Environmental Sciences, University of Arizona, 429 Shantz, Tucson, AZ 85721, USA
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