TEACHING INTRODUCTORY HYDROLOGY USING FIELD EXERCISES, GROUNDWATER FLOW MODELS, AND A CASE STUDY BASED ON "A CIVIL ACTION"

For the past decade, we have been teaching an introductory hydrology course at Bentley College, which incorporates field trips and lab exercises to complement the theories and concepts pertaining to groundwater and surface water flow. Half- to full-day field trips have been made over the years to many local destinations, including: MWRA's Boston Harbor sewage treatment plant on Deer Island, City of Cambridge's water filtration plant, Quabbin Reservoir and Northfield Mountain hydroelectric pump station (western MA), USFS Hubbard Brook Experimental Watershed in West Thornton, NH, and numerous lakes and streams in New England.

Two years ago, we adopted "A Civil Action" (Jonathan Harr, 1996, Vintage Books, New York) as a case study for the hydrology course by analyzing the science as presented in the book and in the Hollywood film, which premiered in late 1999. We added a field trip to the Woburn area to examine the geologic, hydrologic, and topographic setting for the groundwater contamination court case. Finally, we modified a groundwater flow model sold by Ward's Geological Suppliers to simulate visually the Woburn stratigraphy by shaping less permeable materials to represent bedrock and till, which are overlain by permeable sand and gravel, as in the Aberjona River valley. We added two point sources (dye-filled small reservoirs) to simulate potential trichloroethylene contamination from W.R. Grace's Cryogenic plant and J.J. Riley's (Beatrice Foods) tannery. A Manostat 0.5 amp Varistaltic pump is used to simulate pumping tests from various wellheads, which cause contaminants (dye) to migrate from one of the two point sources (the tannery).

Our stylized model serves to illustrate the interaction of groundwater, surface water, and pollutants in the context of the Woburn case through a visual display that students have found very helpful. The impermeable "bedrock" and permeable sediments may be manipulated to demonstrate various flow scenarios. This model is a good illustrative tool, but is not intended to be a realistic representation of the Woburn hydrodynamics, as actual stratigraphic sections, scale, and vertical exaggeration are not rigorously upheld. We are currently customizing a groundwater flow model to simulate more accurately the Woburn case, which we plan to exhibit as a hands-on demonstration at the meeting.