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Using the EXCEL Woburn Flow and Transport Model to Teach Modeling Concepts

Scott Bair
,
Ohio State University
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This activity was selected for the On the Cutting Edge Reviewed Teaching Collection

This activity has received positive reviews in a peer review process involving five review categories. The five categories included in the process are

  • Scientific Accuracy
  • Alignment of Learning Goals, Activities, and Assessments
  • Pedagogic Effectiveness
  • Robustness (usability and dependability of all components)
  • Completeness of the ActivitySheet web page

For more information about the peer review process itself, please see http://serc.carleton.edu/NAGTWorkshops/review.html.


This page first made public: Apr 10, 2006

Summary

Modeling ties together many subjects taught in an introductory hydrogeology course. The goals of this activity are for students to learn why scientists and engineers use models, what types of models are commonly used, and why the steps involved in constructing a predictive model are similar to the steps followed in the 'scientific method.' The Woburn Flow & Transport Model, a series of linked EXCEL worksheets developed by Marinko Karanovich, a former M.S. student at Ohio State University under the guidance of Professor Scott Bair, can be used by students to test the hypotheses (testimony) espoused by the three experts witnesses in the famous 'A Civil Action' trial.

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Context

Audience

Since the beta 2 version of the Woburn Flow & Transport Model was just completed in July 2005, I have not yet used it in a class. Woburn FTM was designed specifically for use in an introductory hydrogeology class as a means to teach students the general concepts of how (numerical) models work and why models are useful to geologists and engineers to address for a wide variety of applied problems.

The Woburn FTM is constructed specifically for the hydrogeologic framework of the Wells G & H Superfund Site in Woburn, Massachusetts, the setting of the famous toxic tort trial described in the book and movie 'A Civil Action.' Woburn FTM uses a modular design similar to MODFLOW and the same mathematical expressions and modeling jargon as MODFLOW. It uses well and river cells and can incorporate spatially variable recharge, hydraulic conductivity, and layer thickness. It uses macros to enter data and pop-up graphs, plots, and contour maps to view input data and simulation results. Woburn FTM simulates three-dimensional steady-state groundwater flow, computes calibration statistics, performs particle tracking, calculates particle travel times, and simulates two-dimensional contaminant transport from one or more sources using the Method of Characteristics.

Data are entered in the Woburn FTM using macros. The numerical solution of heads, particle tracking, and solute transport calculations are also done by macros. To use the Woburn FTM, students need only modify existing values of hydraulic conductivity, aquifer thickness, riverbed permeability, and/or well discharge rates, and then click on the ITERATE button to see graphs, plots, and tables summarizing the results of their simulation pop-up automatically on the linked worksheets. There is an extensive set of HELP screens to assist students in using the worksheets and to describe the geology, hydrology, and usage of wells G and H.

Woburn FTM also could be used in a graduate-level course in numerical modeling to teach the general concepts of flow and transport modeling including iterative methods, water-budget calculations, explicit and implicit numerical solutions, conductance theory, particle tracking, solute transport, and calibration and history matching.

Skills and concepts that students must have mastered

Woburn FTM would best be used near the end of an introductory hydrogeology course, after students have been exposed to construction of potentiometric maps and profiles, heterogeneity, flow line construction, Darcy's Law and calculation of groundwater flow velocities and travel times, stream-aquifer interaction, flow to wells, partial penetration of wells and streams, capture zones of wells, regional flow concepts, and contaminant transport.

How the activity is situated in the course

I envision the Woburn FTM being used at the end of an introductory hydrogeology course as part of a multiple-lecture module dealing with 'Models and Their Application' and wrapping the entire module within the context of the 'A Civil Action' book and movie. It also could be used as part of a capstone project or as a combined lab activity and problem assignment.

Goals

Content/concepts goals for this activity

The goals of the project or assignment would be for students to learn that predictive models need to reproduce one or more measured physical states of the flow system before they are considered to be viable predictive tools, that site-specific models require site-specific information about the hydrogeologic setting and the hydrologic stresses on the flow system, and that three experts sharing a common database can develop three distinctly different hypotheses about how the flow system operates. The overarching goals for wrapping the project or assignment within the context of the famous 'A Civil Action' trial are for students to be exposed to a common venue where science and scientists interact with society, to learn how the U.S. legal system tries to incorporate science in the courtroom, and to realize that a civil trial is a means to resolve a dispute; not a means to find the 'truth.'

Higher order thinking skills goals for this activity

By reading the testimony presented by the three expert witnesses in the 'A Civil Action' trial and comparing their testimony to the results of the students' own model simulations constructed using the Woburn FTM according the experts' testimony, students learn to visualize the geologic setting, interpret the hydrologic data collected by the USGS that was actually used in the famous trial, formulate their own opinions about how the flow system operated from the viewpoint of each party in the lawsuit, and evaluate whether their interpretations are consistent with those of the expert witnesses.

Other skills goals for this activity

I suspect this project / assignment is best done by pairs of students representing one of the three expert witnesses in the trial. It could involve an oral presentation or written assignment of each pair's findings and a subsequent classroom discussion of the role of science in the courtroom.

Description of the activity/assignment

To prepare for this project / assignment, students could view the 'A Civil Action' movie, the instructor could read to them excerpts from the book and/or the trial testimony, and show them images from Woburn, wells G and H, the subsurface geologic materials, geologic cross sections, the trial participants, and the federal courtroom in Boston (see below). The materials in Bair (2001) about scientists in the courtroom, specific (excerpted) testimony presented by the three expert witnesses in the 'A Civil Action' trial, a chart summarizing the differences in their testimony, and the views of a federal judge on the goal of science versus the goal of a civil trial may also be worthwhile reading by the class prior to the assignment.

The instructor could show students the large plates included in the USGS report by Myette and others (1987) that display potentiometric data and contours before and after the critically important aquifer test performed in December 1985 and January 1986, just before the trial, and discuss the significance of the stream discharge measurement made by the USGS upstream and downstream of municipal wells G and H to the experts' testimony and the outcome of the trial.

The instructor could also show the animations of TCE movement from 1960 to 1986 from the five known sources of TCE contamination at the Woburn Wells G & H Superfund Site (W.R. Grace, UniFirst dry cleaners, Olympia Trucking, Beatrice Foods, and New England Plastics) and the animation showing temporal changes in induced infiltration from the Aberjona River to wells G and H that were created by Martin van Oort (M.S., 2005) based on the research of Maura Metheny (M.S., 1998; Ph.D., 2004) at Ohio State University.

The article by Bair and Metheny (2002) concerning the remediation activities subsequent to the famous trial at the Wells G & H Superfund Site could be used to show how groundwater contamination is cleaned up, why different remediation schemes needed to be used in different hydrogeologic settings, and why cleanup to U.S. EPA standards can take decades.

Determining whether students have met the goals

Since I have not yet done this activity in my own hydrogeology class, I can only suggest that evaluations be made on understanding why models are used in society, what steps and procedures must be followed to construct a predictive model to test hypotheses, and what are the difficulties faced by scientists who interact with the public.

More information about assessment tools and techniques.

Download teaching materials and tips

Other Materials

Supporting references/URLs

Science in the Courtroom www.geology.ohio-state.edu/courtroom

Anderson, M.A., and W.W. Woessner, 1992. Applied Groundwater Modeling—Simulation of Flow and Advective Transport; Academic Press, Inc., San Diego, California, 391 p.

Bair, E.S., and M.A. Metheny, 2002. Remediation of the Wells G & H Superfund Site, Woburn, Massachusetts, Ground Water, vol. 40, no 6, p. 657-668.

Bair, E.S., 2001, Models in the Courtroom, Chapter 5, in Model Validation, Perspectives in Hydrological Science, M.G. Anderson and P.D. Bates, eds., John W. Wiley & Sons Ltd., West Sussex, England, 57-76.

Harr, J., 1995, "A Civil Action," Random House, New York, 500 p.
M.A. Metheny, 2004, "Evaluation of Groundwater Flow and Contaminant Transport at the Wells G & H Superfund Site, Woburn, Massachusetts, from 1960 to 1986 and Estimation of TCE and PCE Concentrations Delivered to Woburn Residences," Ph.D. dissertation, Department of Geological Sciences, The Ohio State University, 346 pp.

M.A. Metheny, 1998, "Numerical Simulation of Groundwater Flow and Advective Transport at Woburn, Massachusetts, Based on a Sedimentological Model of Glacial and Glaciofluvial Deposition," M.S. thesis, Department of Geological Sciences, The Ohio State University, 197 pp.

Metheny, M.A., and E.S. Bair, 2001. The Science Behind A Civil Action—The Hydrogeology of the Aberjona River, Wetland and Woburn Wells G and H, West, D.P. and R.H. Bailey, eds., in Guidebook for the Geological Field Trips in New England, 2001 Annual Meeting of the Geological Society of America, p. D1-D25, Boston, Massachusetts.

Metheny, M.A., E.S. Bair, and D.K. Solomon, 2001. Applying variable recharge to a 19-year simulation of groundwater flow in Woburn, Massachusetts and comparing model results to 3H/3He ages, Seo, H.S., E. Poeter, C. Zheng, and O. Poeter, eds., in MODFLOW 2001 and Other Modeling Odysseys—Conference Proceedings, vol. 2, p. 783-789, International Ground Water Modeling Center, Colorado School of Mines, Golden, Colorado.

Myette, C.F., J.C. Olympio, and D.G. Johnson, 1987, Area of influence and zone of contribution to Superfund-site Wells G and H, Woburn, Massachusetts; U. S. Geological Survey, Water-Resources Investigations Report 87-4100, 21 p.