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In a distinctive summer engineering research project, senior Marquis Scholar Sandra Doyle of Springfield, Pa., a graduate of Cardinal O’Hara High School, took aim at one of the most common classes of groundwater contaminants in North America, chlorinated solvents, such as trichloroethene (TCE) and tetrachloroethene (PCE), which have had widespread use in industry as degreasers.
As a participant in Lafayette’s EXCEL Scholars program, in which students collaborate closely with faculty members on research projects while earning a stipend, Doyle worked with David Brandes, assistant professor of civil and environmental engineering, on tests to determine the fluid properties of TCE and PCE and to see if an alcohol and salt solution removes them from aquifers they have contaminated.
According to Brandes, companies sometimes used to take spent TCE to the back of the plant and dump it on the ground. “It works great as a degreaser,” he says. “What people didn’t realize was that it was toxic.” Today, the chemical sometimes leaks from sewers and tanks on its way chemical treatment plants.
Brandes’ areas of expertise and interest include hydrology and environmental engineering. He teaches courses in environmental engineering, fluid mechanics, engineering hydrology, and groundwater hydrology. In addition to his work with Doyle on remediation of groundwater contaminants he is also researching the nonlinear dynamics of hillslope and watershed runoff response, and stormwater runoff quality dynamics.
Doyle says, “TCE and PCE are heavier than water, and they sink to the bottom, so it’s hard to get rid of them by pumping water in. But the alcohol and salt solution is heavier than the contaminant, so it works.”
The project involved a lab simulation of the cosolvent flushing process using a glass-walled test cell packed with sand. Brandes and Doyle contaminated the sand, took video footage with a digital camera as they pumped in the alcohol solution, and analyzed the effluent. They observed how differences in the flushing substances’ density and viscosity caused some to work more effectively than others.
Doyle says the research has prompted her to consider graduate school, now that she has “a better understanding of why each step in the project takes so long.”
Last spring she was a Writing Associate in the College Writing Program, assisting students with their assignments in the course “Engineering Professionalism and Ethics.” She is a member of the Women’s Rugby Club and a member of Alpha Phi sorority.