A Civil Action - The Woburn Toxic Trial > Instructor Materials > Module 5 - Groundwater Flow > Groundwater Flow Development Page

Groundwater Flow Development Page

Kevin Svitana, Otterbein College, Scott Bair, Ohio State University
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Summary

Understanding the effects of groundwater pumping on flow direction and rates is a key topic of this module. Students focused on a class emphasizing hydrology explore the methods of doing numerical solutions to groundwater flow effected by pumping. Goals for this module is to understand the complexity of groundwater flow caused by well pumping. Understanding the effect of discontinuous pumping of Wells G & H, and the resulting migration of TCE through the subsurface is an important aspect of this module. Students are also introduced to the potential of other source contaminants making into groundwater captured by Wells G & H as a result of dewatering Aberjona River. Resources are presented that enables students to formulate mathematical models of groundwater flow. It's the discretion of the instructor to evaluate the depth of mathematical application.

Learning Goals

This module serves two purposes, one, to make students aware of the groundwater flow issues related to the Woburn case, and second, it provides an introduction to mathematical solutions for evaluating groundwater flow. For classes focusing on the integrative studies aspect, exploring the mathematical approach to defining groundwater flow is probably less important, but emphasizing problems with related to this modeling approach are important since the experts essentially reviewed the same data and came to different conclusions. This demonstrates the dynamic aspect of scientific investigation, and the need for non-science persons to appreciate the scientific process. For classes focusing on hydrogeology, this module lays a foundation for numerical analysis of groundwater flow which directly relates to fate and transport of contaminants.

Constructing and analyzing groundwater contour maps made from pe-pumping data as well as data from pumping conditions. The goal is to have the user understand the changes effected by pumping withdrawal of groundwater from saturated zone and use this information as a predictor of how contaminant migration would be affected by pumping.

Context for Use

Building on Darcy's Law as a means to explain fluid flow through porous media is important in this module. The degree of mathematical application is dependent on the focus of the class. This module is likely to be more effective if it is used in sequence with prior modules. But data from this module can be used as a stand-alone exercise. Video clips included with the modules also provide dramatization of the effect of pumping versus non-pumping. These video images are intended to provide a simulation of conditions occurring in the subsurface in a Woburn-based model.

Description and Teaching Materials

Excel-based spreadsheet using calculations from the Theim equation are supplied with module. Students can vary in pumping rate inputs and visually see through graphical outputs the changes in groundwater drawdown and flow direction. The level of mathematical application is the discretion of the instructor.

Teaching Notes and Tips

Contouring is a basic skill required for all earth scientists. Having students carefully develop contours of groundwater flow is a key part of this learning effort. Suggestions on how they can "eyeball interpolate" their contours as well as other hints regarding the construction and interpretation of contoured surface data.

Assessment

Assessment can be completed by evaluating and grading the various inputs from the Excel spreadsheet produced by the students and grading them for their interpretation of the variations of pumping wellflow rate. Another option would be having the students self evaluate in class so that instruction can be shared by the students participating in this exercise. Other than quizzing the basic concepts of contouring, this exercise does not lend itself to a question/answer assessment format.

References and Resources

Groundwater and Surface Water a Single Resource

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