Active Spreading: Hydraulics for Enhancing Groundwater Remediation

Sather, Lauren J.; Neupauer, R. M.; Mays, D. C.; Crimaldi, John P.; Roth, E. J.

doi:10.1061/(asce)he.1943-5584.0002167

Cited by 4 publications

(5 citation statements)

References 39 publications

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“…Similarly, spatial distributions of solutes between simulations and experiments are also highly correlated, which validates the numerical modeling approach. This validation provides a foundation for additional simulations on EIE, beyond the scope of this work, that are reported elsewhere (Sather et al., 2022). Differences between experiments and simulations are most notable during stretching events when concentration gradients are being sharpened.…”

Section: Discussionmentioning

confidence: 71%

“…Their solution showed that EIE works in tandem with heterogeneity to amplify mixing through both longitudinal and transverse dispersion. Recognizing that longi tudinal dispersion is generally much larger than transverse dispersion (i.e., by one order of magnitude), one strategy is to manipulate the plume to maximize its interfacial area, and then to manipulate the velocity field to make streamlines generally perpendicular to the plume interface (Sather et al, 2022). This is exactly the rationale behind the oscillating sequence, where steps 1-2 stretch the initially circular plume into an ellipse, and steps 3-5 impose dipole velocity fields, in alternating directions, such that the plume oscillates around its initial position with the velocity field generally perpendicular to its interface (Figure 7).…”

Section: Discussionmentioning

confidence: 99%

“…The second EIE sequence, shown in Table 2, is called the oscillating sequence. This sequence was chosen to exploit the findings of Sather et al (2022), who showed that active spreading, and therefore reaction, is highest where the local velocity is generally perpendicular to the plume interface.…”

Section: Conceptual Modelmentioning

confidence: 99%

See 2 more Smart Citations

Experiments and Simulations on Plume Spreading by Engineered Injection and Extraction in Refractive Index Matched Porous Media

Sather

Roth

Neupauer

et al. 2023

Water Resources Research

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Reactive transport, the coupled set of processes that control the source, movement, reaction, and fate of solutes in porous media, is fundamental to a range of geophysical processes including soil weathering, element cycling, in-situ mining, and groundwater remediation. Because reactive transport depends on hydrological, microbiological, geochemical, and physical processes, it constitutes a major branch within the broad and interdisciplinary heading of hydrobiogeochemistry (Meile & Scheibe, 2019). Here we focus on physical processes, specifically fluid velocity, on the premise that biogeochemical processes depend on the delivery of reagents and the removal of wastes that are provided almost entirely by fluid advection (Kitanidis, 2012).A particular motivation for this work is groundwater remediation, the art and science of sequestering or destroying contaminants in aquifers, the geologic structures that store and transmit useful quantities of water for municipal, industrial, and environmental purposes. Groundwater remediation often calls for an amendment to be introduced into the aquifer. Successful in-situ remediation requires that the remediation amendment and contaminant occupy the same pore space, at which point molecular diffusion permits the desired reaction (Kitanidis, 1994). In other words, reaction requires mixing, the result of molecular diffusion, which increases the volume into which mass is dissolved and consequently provides dilution. In contrast, spreading is defined as solute redistribution by advection, on any scale, without dilution, depending entirely on the velocity field. Spreading enhances mixing by increasing the interfacial area between plumes of differing chemical composition, and by sharpening the concentration gradients at the plume interface, both of which serve to increase mass transport by molecular diffusion (Le Borgne et al., 2010;Villermaux, 2019; Section 2.2). An elegant example of improved remediation through improved spreading has recently been provided by Ye et al. (2021), who used multi-screen wells to inject multiple amendment plumes with correspondingly increased interfacial area. Moreover, spreading takes place at the plume scale, which is an important distinction, because numerical and theoretical studies have shown that different processes dominate at the pore scale versus the plume scale (Jose & Cirpka, 2004).

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Section: Discussionmentioning

confidence: 71%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Experiments and Simulations on Plume Spreading by Engineered Injection and Extraction in Refractive Index Matched Porous Media

Sather

Roth

Neupauer

et al. 2023

Water Resources Research

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“…Wang et al (2022) performed two-phase flow simulations of an engineered injection and extraction sequence, and showed that this sequence can improve removal efficiency and mixing. Sather et al (2022) simulated the mixing behavior and reaction of two solute plumes based on four different active spreading protocols using MODFLOW-2000 (version 1.12.00;Harbaugh et al 2017) and RW3D (version 6.0; Salamon et al 2006).…”

Section: Introductionmentioning

confidence: 99%

“…Sather et al. (2022) simulated the mixing behavior and reaction of two solute plumes based on four different active spreading protocols using MODFLOW‐2000 (version 1.12.00; Harbaugh et al. 2017) and RW3D (version 6.0; Salamon et al.…”

Section: Introductionmentioning

confidence: 99%

The Role of Rotated Potential Mixing Protocols on the Behavior of a Conservative Reagent

Cho,

Thomson

2024

Groundwater Monitoring Rem

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Chaotic advection is defined as the generation of “small‐scale structures” from the repeated stretching and folding of fluid elements in a laminar flow regime that has the potential to enhance mixing and improve treatment effectiveness. Rotated potential mixing (RPM) flow is one configuration used to invoke chaotic advection and involves periodically re‐oriented dipole flow through the transient switching of pressures at a series of radial wells. In this study, we relied on conventional models used by remediation practitioners to represent the expected flow and transport behavior of a conservative reagent subjected to chaotic advection by an RPM flow system, and then explored the impact of engineering controls on reagent mixing behavior. The various lines of evidence demonstrated that this modeling approach captured the key features of the expected transport behavior reported in other studies. Visual observations of the reagent distribution, and quantitative metrics of mixing behavior highlighted the different responses that are possible by the various combinations of RPM flow parameters explored. The results show the importance of combining theoretical considerations with practical limitations when designing an RPM flow system. The flow rate and pumping duration have direct consequences on the degree of reagent spreading and mixing. The use of the same RPM flow protocol in a heterogeneous K field led to a significantly greater degree of reagent mixing than in a homogeneous K system. The results from this investigation have important implications for the design of RPM flow protocols to promote enhanced reagent mixing and thereby improve treatment effectiveness.

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