Students in my hydrogeology course at Case Western Reserve University just turned in their write-ups from our field trip to the university’s Squire Valleevue and Valley Ridge Farm.
The university has a well field (shown below) that taps into an aquifer of Berea Sandstone (shown above in the outcrop of a nearby stream) confined above and below by Orangeville and Bedford Shale.
Using a generator and submersible pump, we conducted a pump test, during which the students measured draw down in the wells.
They installed a pressure transducer to record continuous data of depth to water.
We had some technical difficulties and mechanical challenges with pressure transducers and the sounding tape used to measure depth to water, but this provided a great opportunity for students to examine alternative methods and equations necessary to calculate aquifer properties with draw down data from only one well.
Students measured pumping rate to ensure a constant rate of pumping used in calculations of aquifer properties during the pump test.
Using the data they collected, students estimated aquifer properties including transmissivity, storativity, hydraulic conductivity, and discharge per unit width of aquifer.
They also conducted electromagnetic surveys using an EM31 to measure conductivity and relative changes in moisture in the shallow subsurface. Comparing depth to water values in the wells and differences in EM measurements from two weeks prior, students were able to infer relative changes in water table and aquifer levels.
The students set up differential GPS surveys to obtain the location and elevation of the wells and EM31 survey points.
Examination of topographic and geologic maps of the farm provided additional context to their surveys and examination of the GPS points in Google Earth.
Differential GPS surveys, examination of the well logs, and a hike along an incised stream to see exposures of the underlying stratigraphy allowed students to infer relative connectivity between the water table, nearby ponds, a stream, and the sandstone aquifer.
Examination of seepage faces at bedrock exposures and a closer look at the sandstone and shale provided insight into relative porosity and differences in hydraulic conductivity of the the different rock types. Visual examination of the rock types reinforce the understanding of differences between the sandstone aquifer and the shale aquitards.
The entire report aimed to provide hands-on experience with hydrogeological analysis, an understanding of water table and confined water connectivity, the role of underlying geology on the movement of groundwater, and a regional context for aquifer systems and local groundwater connectivity.