Integration of traditional and innovative characterization techniques for flux-based assessment of Dense Non-aqueous Phase Liquid (DNAPL) sites

Basu, N. B.; Suresh, Pradeep; Rao, C. Lakshmana; Poyer, Irene C.; Nandy, Subhas; Megharaj, Mallavarapu; Naidu, Ravi; Davis, Gordon B.; Patterson, Bradley M.; Annable, Michael D.; Hatfield, Kirk

doi:10.1016/j.jconhyd.2008.12.005

Cited by 33 publications

(30 citation statements)

References 34 publications

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“…The initial pe-remediation mass was estimated using the reported inventory of solvent disposal for the MOT site. For the PGN and CD sites, the initial pre-remediation mass was estimated based on fitting a mass-depletion function to the temporal contaminant mass discharge data (Butcher and Gauthier, 1994; Basu et al, 2009; Brusseau et al, 2013). The power function is one such, widely used, function (e.g., Zhu and Sykes, 2004; Falta et al, 2005):

normald normalM / normald normalt = - false(Q_{0} C_{0} / {normalM}_{0}^{Γ} false) M^{Γ}

where C 0 is initial contaminant concentration, M 0 is initial contaminant mass, M is contaminant mass at time t, Q 0 is initial discharge, Q is discharge at time t, and Γ is the power index term, representing the impact of a host of conditions and processes on mass-removal behavior.…”

Section: Methodsmentioning

confidence: 99%

Assessing contaminant-removal conditions and plume persistence through analysis of data from long-term pump-and-treat operations

Brusseau

Guo

2014

Journal of Contaminant Hydrology

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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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normald normalM / normald normalt = - false(Q_{0} C_{0} / {normalM}_{0}^{Γ} false) M^{Γ}

Section: Methodsmentioning

confidence: 99%

Assessing contaminant-removal conditions and plume persistence through analysis of data from long-term pump-and-treat operations

Brusseau

Guo

2014

Journal of Contaminant Hydrology

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“…For long-term monitoring, a permanent device is more appropriate to avoid these variations of measured concentrations. Chlorinated solvent monitoring with the multilevel sampler showed that the most contaminated layer was located at a depth between 4 and 6 m. However, this does not mean that the flux of contaminant is maximum at this depth [19]. Indeed, the flux in the most contaminated layer may be low and consequently limit the decontamination efficiency [20].…”

Section: Discussionmentioning

confidence: 98%

Validation of a multilevel sampling device to determine the vertical variability of chlorinated solvent in a contaminated aquifer

Barnier¹,

Palmier

Atteia³

2013

Environmental Technology

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The vertical heterogeneity of contaminant concentrations in aquifers is well known, but obtaining representative samples is still a subject of debate. In this paper, the question arises from sites where numerous fully screened wells exist and there is a need to define the vertical distribution of contaminants. For this purpose, several wells were investigated with different techniques on a site contaminated with chlorinated solvents. A core-bored well shows that a tetrachloroethene (PCE) phase is sitting on and infiltrating a less permeable layer. Downstream of the cored well, the following sampling techniques were compared on fully screened wells: low flow pumping at several depths, pumping between packers and a new multilevel sampler for fully screened wells. Concerning low flow rate pumping, very low gradients were found, which may be due to the existence of vertical flow inside the well or in the gravel pack. Sampling between packers gave results comparable with the cores, separating a layer with PCE and trichloroethene from another one with cis 1,2-dichloroethene and vinyl chloride as major compounds. Detailed sampling according to pumped volume shows that even between packers, cleaning of the inter-packer volume is necessary before each sampling. Lastly, the proposed new multilevel sampler gives results similar to the packers but has the advantages of much faster sampling and a constant vertical positioning, which is fairly important for long-term monitoring in highly stratified aquifers.

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“…Whilst higher resolution site assessment alternative technologies have become increasingly recommended (Anneser et al, 2008;Basu et al, 2009;Kram et al, 2001;ITRC, 2015), their use is still perceived to represent a small fraction of the site characterization effort worldwide that still predominantly involves monitoring wells. Alternatives to characterize source-zone mass distribution include, detailed core sampling (Parker et al, 2003), inter-well partitioning tracer tests (Annable et al, 1998) and direct-push methods involving direct water sampling ("groundwater profiling") and indirect measurements using sensorbased tools such as the Membrane Interface Probe (Adamson et al, 2014;Guilbeault et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Monitoring well utility in a heterogeneous DNAPL source zone area: Insights from proximal multilevel sampler wells and sampling capture-zone modelling

McMillan

Rivett

Wealthall³

et al. 2018

Journal of Contaminant Hydrology

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This version is available at https://strathprints.strath.ac.uk/63641/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.ukThe Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output. ABSTRACTGroundwater-quality assessment at contaminated sites often involves the use of short-screen (1.5 to 3 m) monitoring wells. However, even over these intervals considerable variation may occur in contaminant concentrations in groundwater adjacent to the well screen. This is especially true in heterogeneous dense nonaqueous phase liquid (DNAPL) source zones, where cm-scale contamination variability may call into question the effectiveness of monitoring wells to deliver representative data. The utility of monitoring wells in such settings is evaluated by reference to high-resolution multilevel sampler (MLS) wells located proximally to shortscreen wells, together with sampling capture-zone modelling to explore controls upon well sample provenance and sensitivity to monitoring protocols. Field data are analysed from the highly instrumented SABRE research site that contained an old trichloroethene source zone within a shallow alluvial aquifer at a UK industrial facility. With increased purging, monitoring-well samples tend to a flow-weighted average concentration but may exhibit sensitivity to the implemented protocol and degree of purging. Formation heterogeneity adjacent to the wellscreen particularly, alongside pump-intake position and water level, influence this sensitivity. Purging of low volumes is vulnerable to poor reproducibility arising from concentration variability predicted over the initial 1 to 2 screen volumes purged. Marked heterogeneity may also result in limited long-term sample concentration stabilization. Development of bespoke monitoring protocols, that consider screen volumes purged, alongside water-quality indicator parameter stabilization, is recommended to validate and reduce uncertainty when interpreting monitoring-well data within source zone areas. Generalised recommendations on monit...

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Integration of traditional and innovative characterization techniques for flux-based assessment of Dense Non-aqueous Phase Liquid (DNAPL) sites

Cited by 33 publications

References 34 publications

Assessing contaminant-removal conditions and plume persistence through analysis of data from long-term pump-and-treat operations

Assessing contaminant-removal conditions and plume persistence through analysis of data from long-term pump-and-treat operations

Validation of a multilevel sampling device to determine the vertical variability of chlorinated solvent in a contaminated aquifer

Monitoring well utility in a heterogeneous DNAPL source zone area: Insights from proximal multilevel sampler wells and sampling capture-zone modelling

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