Investigating a Real-Life Groundwater Contamination Event
Key words: Groundwater contamination, case study, TCE
Skills and concepts that students must have mastered
How the activity is situated in the course
Content/concepts goals for this activity
Higher order thinking skills goals for this activity
Other skills goals for this activity
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
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)