Ryan Foster and Jaron Borg, seniors at UVM, are working with Dr. Mandar Dewoolkar, an assistant professor within the department of civil and environmental engineering, on evaluating if a new analytical method is an effective measurement of stream and river bank stability. Their research is supported by funding provided by a Richard Barrett Scholarship and a U.S. Geological Survey grant.Introducing their research, Foster explains that “when spring runoff or heavy rain occurs, the soil in stream banks becomes saturated and heavy, and a reduction in the shear strength of the soil follows.” This increased weight and decrease in soil strength resultsin the collapse of stream banks. When the banks of Lake Champlain’s tributaries collapse, high levels of sediments and phosphorus reach its shores. Large algae blooms develop and the lake’s ecosystem, as well as fishing and recreation, are disturbed. “No one wants to look at a green lake, and no one wants to swim in one either,” Foster continues, stressing that “fish are the species most affected by the algae growth because it takes away food sources and clouds up the lake.” Foster spent this past summer measuring the shear strength of the banks of the Winooski River at eight locations near the Ethan Allen Homestead. “Three inch diameter boreholes were drilled and the Borehole Shear Test (BST) was conducted in the boreholes to measure the shear strength of the soil.” Concurrently, undisturbed soil samples were also collected “in order to conduct the direct shear and tri-axial tests in our laboratory.” Borg has been working in Dr. Dewoolkar’s laboratory to test the shear strength of the undisturbed soil samples Foster collected using the direct shear and tri-axial tests. When he finishes, the laboratory data “will be compared to Foster’s field data and the effectiveness of the BST can be evaluated” Borg said. The direct shear and tri-axial tests are expensive laboratory methods, whereas the BST is both cost-effective and convenient. As such, Foster and Borg’s ultimate goal is to demonstrate the effectiveness of the Borehole Shear Test for measuring stream and riverbank stability.
