EOSC 541 · Multi-component Reactive Transport Modeling in Groundwater

Gain basic familiarity with reactive transport processes, formulation and governing equations for geochemical and multicomponent reactive transport models, common solution and discretization methods

Develop an appreciation for interactions between flow processes, solute transport, gas transport, and geochemical reactions – in saturated and unsaturated porous media by means of case studies

Course Content:

Introduction to reactive transport processes in saturated groundwater systems and in the vadose zone. Effect of major biogeochemical reactions on groundwater composition in natural and contaminated aquifers.

Logistics:

We will start the course with a brief “theory block” (lectures and self-guided reading) on the purpose and basics of multicomponent reactive transport. We will then move on to work through a series of case studies. The case studies will be based on assigned readings that present practical problems treated to groundwater contamination and remediation, in most cases using reactive transport modeling as a quantitative analysis tool. Class meetings will be used to discuss the problems covered in the case studies with the aim to identify the flow, transport and reaction processes that control water quality. For each reading assignment, I will ask you to submit a brief point form summary of the paper prior to the class. Select reading assignments will be complemented with a reactive transport modeling assignment (PHREEQC and MIN3P-THCm). The course will conclude with a final exam.

Course outline:

Part 1:

1. Purpose of Reactive Transport Modeling (background reading: Postma and Appelo, 2000, Steefel et al., 2005)
2. Methods for simulating reactive transport, governing equations, introduction of coupling between transport processes and reactions. (Optional background reading: Steefel and MacQuarrie, 1996, Steefel et al., 2015). Starting with the advection dispersion equations, we will review the introduction of simple linear reactions (decay, adsorption), followed by nonlinear reactions and move on to multispecies and multicomponent systems. Model formulations for coupling of geochemical processes and transport (substitution methods and sequential coupling methods).

Part 2: Case studies

1. Attenuation of acid mine drainage in aquifers (Bain et al, 2001)
2. Acid mine drainage release and attenuation in mine tailings & model verification strategies (Mayer et al., 2015)
3. Processes controlling acid mine drainage generation in waste rock (Lefebvre et al., 2001a,b)
4. Geochemical controls on secondary water quality impacts at a crude oil spill (Ng et al., 2015)
5. Vadose zone natural attenuation of organic compounds at a crude oil spill site (Molins et al., 2010)
6. Quantification of source zone natural attenuation rates at hydrocarbon contaminated sites (Sihota and Mayer, 2012)
7. Groundwater remediation of chlorinated solvents using a permeable reactive barrier (Yabusaki et al., 2001)
8. Groundwater remediation of acid mine drainage using a permeable reactive barrier (Mayer et al., 2006)
9. Permanganate-based in-situ chemical oxidation of chlorinated solvents (Henderson et al., 2009)
10. Gas migration as a result of leaky well bores – Migration and fate of methane (Roy et al., 2016)

Possible Assignments:

1. Attenuation of acid rock drainage in a fully saturated aquifer (complements case study 1, PHREEQC)
2. Weathering of mine waste – diffusive O2 ingress (complements case study 2, MIN3P)
3. Simulating permeable reactive barriers (complements case study 7, PHREEQC)
4. Natural attenuation of petroleum hydrocarbons in the vadose zone (complements case studies 5 and 6)

References and readings:

Bain, J. G., K. U. Mayer, J. W. H. Molson, D. W. Blowes, E. O. Frind, R. Kahnt and U. Jenk, 2001. Assessment of the suitability of reactive transport modelling for the evaluation of mine closure options, J. Contam. Hydrol., 52:109-135

Henderson, T.H., K. U. Mayer, B. L. Parker, and T.A. Al., 2009. Three-dimensional density-dependent flow and multicomponent reactive transport modeling of chlorinated solvent oxidation by potassium permanganate, J. Contam. Hydrol., 106:183-199

Lefebvre, R.., D. Hockley, J. Smolensky, and P Gelinas, 2001. Multiphase transfer processes in waste rock piles producing acid mine drainage, 1: Conceptual model and system characterization, Journal of Contaminant Hydrology, 52:137–164

Lefebvre, R.., D. Hockley, J. Smolensky, and A Lamontagne, 2001. Multiphase transfer processes in waste rock piles producing acid mine drainage, 2. Applications of numerical simulation, Journal of Contaminant Hydrology, 52:165–186

Mayer, K.U., S. G. Benner, and D. W. Blowes, 2006. Process-based reactive transport modeling of a permeable reactive barrier for the treatment of mine drainage, J. Contam. Hydrol., 85:195-211

Mayer, K.U., P. Alt-Epping, D. Jacques, B. Arora and C. I. Steefel, 2015. Benchmark problems for reactive transport modeling of the generation and attenuation of acid rock drainage, Computational Geosciences, Special Issue on: Subsurface Environmental Simulation Benchmarks, doi: 10.1007/s10596-015-9476-9

Molins, S., K. U. Mayer, R. T. Amos, and B. A. Bekins, 2010. Vadose zone attenuation of organic compounds at a crude oil spill site - Interactions between biogeochemical reactions and multicomponent gas transport, J. Contam. Hydrol, 112:15-29

Roy, N, J. Molson, J.M. Lemieux, D. Van Stempvoort, D and A. Nowamooz, 2016. Three-dimensional numerical simulations of methane gas migration from decommissioned hydrocarbon production wells into shallow aquifers, Water Resources Research, 52:5598-5618, DOI: 10.1002/2016WR018686

Ng, Gene-Hua Crystal, Barbara A. Bekins, Isabelle M. Cozzarelli, Mary Jo Baedecker, Philip C. Bennett, Richard T. Amos, and William N. Herkelrath, 2015. Reactive transport modeling of geochemical controls on secondary water quality impacts at a crude oil spill site near Bemidji, MN, Water Resources Research DOI:10.1002/2015WR016964

Postma, D. and C.A.J Appelo, 2000. Reduction of Mn-oxides by ferrous iron in a flow system: Column experiment and reactive transport modeling, Geochim. Cosmochim. Acta, 64:1237-1247.

Sihota, N.J., and K.U. Mayer, 2012. Characterizing vadose zone hydrocarbon biodegradation using CO2-effluxes, isotopes, and reactive transport modeling, Vadose Zone Journal, 11, doi:10.2136/vzj2011.0204.

Steefel, C.I. and K.T.B. MacQuarrie, 1996. Approaches to modeling reactive transport in porous media, in: P.C. Lichtner, C.I. Steefel, E.H. Oelkers (Eds.), Reactive Transport in Porous Media, Reviews in Mineralogy, vol. 34, pp. 83–125.

Steefel, C.I., DePaolo, D., Lichtner, P.C.: Reactive transport modeling: An essential tool and a new research approach for the Earth sciences. Earth Planet. Sci. Lett. 240, 539–558 (2005)
Steefel, C.I., C.A.J. Appelo, B. Arora, D. Jacques, T. Kalbacher, O. Kolditz, V. Lagneau, P.C. Lichtner, K. U. Mayer, J.C.L. Meeussen, S. Molins, D. Moulton, D.L. Parkhurst, H. Shao, J. Šimůnek, N. Spycher, S.B. Yabusaki, and G.T. Yeh, 2015. Reactive transport codes for subsurface environmental simulation, Computational Geosciences, Special Issue on: Subsurface Environmental Simulation Benchmarks, doi:10.1007/s10596-014-9443-x

Yabusaki, S., K Cantrell, B. Sass, and C. Steefel., 2001. Multicomponent Reactive Transport in an In Situ Zero-Valent Iron Cell, Environmental Science & Technology, 35, 1493-1503.