Investigating a Real-Life Groundwater Contamination Event

Peter Riemersma, Grand Valley State University

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This assignment is designed as a final project for students in my undergraduate 3 credit non lab elective geohydrology course. Students work in pairs to analyze an actual, local contaminated site (Delphi) and use raw data from consulting reports (boring logs, water levels, chemical water analyses) to prepare a geologic cross-section, water table map and contaminant plume map. Students are assigned different lines of cross section, water level dates and contaminant types. Students examine the variety of different figures and maps to better characterize hydrogeologic and water quality conditions over the entire site and answer some assigned questions. This project is an opportunity for students to apply skills they learned in the course (contouring, groundwater flow) to investigate an existing groundwater contamination event. It also provides the kind of "practical" experience the students can highlight in a job interview.

Key words: Groundwater contamination, case study, TCE

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This project is a for a 3 credit, non-lab, elective undergraduate Geohydrology course (Geo 440) for upper level students. Physical geology (Geo 111) is the only prerequisite for the course that attracts geology majors but some natural resource management majors as well.

Skills and concepts that students must have mastered

Students need to have an understanding of how to draw geologic cross-sections and contour water level and chemical concentration data. They must also be able to relate how changes in the aquifer thickness and hydraulic conductivity would impact hydraulic gradients and groundwater velocities. They should be able to apply Darcy's law to estimate groundwater flow velocities at the site.

How the activity is situated in the course

The project is started about 2/3 of the through the course, with analysis occurring the last week.


Content/concepts goals for this activity

The goal of this assignment is to have students apply their hydrogeological knowledge to characterize geologic and chemical conditions at a site with contaminated groundwater.

Higher order thinking skills goals for this activity

The focus of the project is on visualization and analysis of data. The assignment is challenging, as data is limited in many areas and analysis requires a synthesis of the geology, groundwater flow directions, and an understanding of such chemical properties as transformation.

Other skills goals for this activity

Skill goals for this project also include constructing geologic cross-sections, water table maps, contaminant plume maps at an actual site.

Description and Teaching Materials

Case Study of Groundwater Contamination at the Delphi Corporation, Wyoming, Michigan

Close to Grand Valley State University, groundwater contamination of an unconsolidated sand and gravel aquifer is used as a case study that requires hydrogeology students to apply skills and concepts learned throughout the semester. Newspaper articles of the groundwater contamination are used to introduce students to the project and highlight its importance. In some cases the newspaper articles can be used to identify common misconceptions that the public has about groundwater contamination. The case study is a great example of how the groundwater flow direction controls the shape and distribution of the contaminant plume and how the subsurface geology can impact groundwater flow. Irregular bedrock topography and local bedrock ridges influence hydraulic gradients in the region and groundwater flow in the area. The distribution of TCE and its breakdown products 1,2 –DCE and vinyl chloride in groundwater at the Delphi plant in Wyoming Michigan illustrate the impact of chemical processes on contaminant transport.

It's not uncommon for local libraries to act as report repositories for Superfund sites and other environmental groundwater issues. Environmental consulting reports on reserve in the Wyoming, Michigan Library describe groundwater contamination at the Delphi plant and were manually copied to provide the raw data for this case study. The raw data includes 94 boring logs, well construction diagrams, 20 episodes of water level measurements, and groundwater analytical chemistry results (4 - 6 occasions) collected over several years at the site.

Each student is assigned individually a specific geologic cross-section, water table map, and contaminant plume map to construct, although there was some overlap to accommodate more students (and illustrate differences in interpretation). At the completion of individual assignments, student are asked to examine all the different cross-sections and maps and assess the geology from different perspectives, observe changes in groundwater flow directions seasonally, and monitor the distribution of different chemicals in the subsurface over time as well. A number of Site Analysis Questions require observation and synthesis of information over the entire site.

This project is flexible and instructors can modify this assignment as they are given access to the data. For example different geologic cross-section lines can be specified. Because of time constraints, I have summarized water quality data and provided a geologic cross-section template, both of which the students could prepare from the data provided. Students appreciate the opportunity to do what working hydrogeologists do.

1. Instructions for geologic cross-sections, water table and contaminant plume figures
2. Newspaper articles about the Delphi Site
3. Background Data (borehole lithology, well construction, water levels, chemical data)
4. Base map for water table maps and contaminant plume , lines of geologic cross-section with wells plotted)
5. Interpretative questions about site conditions and Example Figures

Delphi Figure Instructions (Microsoft Word 154kB Apr30 13)
Newspaper Articles about the Delphi Site (Microsoft Word 66kB Apr30 13)
Background data for Delphi Site (Acrobat (PDF) 16.3MB Apr30 13)

General Geo Cross-Section Base Map (Excel 2007 (.xlsx) 15kB Jun4 13)
Base maps for Delphi Project (Acrobat (PDF) 290kB Apr30 13)
Final Site Analysis and Example Figures (Microsoft Word 4.9MB Apr30 13)

Teaching Notes and Tips


I assess the student figures and highlight their mistakes or omissions. I grade the student written responses to the analysis questions but don't post an answer key to preserve the assignment for future use.

References and Resources

Haley and Aldrich of Michigan, Inc, February 2005, Data Summary Package Transmittal – Field Event #3, Voluntary RCRA Facility Investigation (consultant report)