Keynote - Do You Know Where Your Aquitards Are?

Monday, September 23, 2019: 8:30 a.m.
Jessica Meyer, Ph.D. , University of Iowa, Iowa City, IA

Do You Know Where Your Aquitards Are? A Case for Hydraulically Calibrated Geology as the Foundation for Robust CSMs of Contaminated Fractured Rock Systems

Delineation of aquitard hydrogeologic units (HGUs) is critical to the development of conceptual site models (CSMs) for contaminated sites. However, aquitards are often delineated assuming a strong correlation between lithology and hydraulic conductivity. This assumption has not been rigorously tested in bedrock where fracture characteristics control bulk hydraulic conductivity. The objective of this research was to identify HGUs for a contaminated sedimentary rock site using a direct hydraulic dataset. Twelve boreholes were continuously cored to between 53 and 152 m bgs, comprehensively characterized, and instrumented with high-resolution multilevel systems. Head profiles were measured at each location several times per year over multi-year periods. The position/thickness of distinct vertical gradients occurred consistently in each profile indicating multiple, thin intervals of rock functioning as aquitards. The position of these aquitards was not predicted by lithostratigraphy but was strongly associated with sequence stratigraphy. The hydraulic contrasts identified by the head profiles were combined with sequence stratigraphy to delineate 6 aquitards and 4 aquifers. This hydraulically calibrated geologic framework was independently verified against the DNAPL and dissolved phase contaminant mass distributions. These HGUs now serve as the framework for numerical models which are needed to predict future conditions and evaluate remediation feasibilities and timeframes.

Jessica Meyer, Ph.D., University of Iowa, Iowa City, IA
Dr. Meyer is currently an adjunct professor in the School of Environmental Sciences at the University of Guelph and a senior research scientist for the G360 Institute for Groundwater Research. She earned a B.Sc. in Environmental Geology from the University of Montana and a M.Sc. (University of Waterloo) and Ph.D. (University of Guelph) in hydrogeology. Dr. Meyer’s research focuses on field based characterization of fractured sedimentary rock flow systems with emphasis on understanding the relationship between the hydraulic and geologic structure of the subsurface. In addition to her research experience, she has 14 years of experience managing large multifaceted field based research projects at industrial sites.