Field survey and characterization of southern Ontario tills and St. Lawrence Valley marine clays****

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Quaternary glacial deposition has covered much of southern Ontario with tills and the Saint Lawrence Valley with glaciolacustrine or marine fines. Rivers incised into these materials exhibit particular geomorphologic behavior due to the interaction of the river flows with the bed and bank sediments. Civil engineering works built either in (e.g. dams, bridge piers, etc.), beside (linear infrastructure such as roads, railways, etc.) or across (e.g. bridges, etc.) such rivers must consider the erosion of these cohesive sediments particularly where river flows are modified by built structures. There is currently very little knowledge about the threshold and rate of erosion of these materials, nor about their geographic distributions and the range of material properties between different strata and deposits. This leads to design challenges and long-term maintenance considerations for hydraulic, geotechnical, transportation and structural engineering projects that can result in increased lifecycle costs and the potential for failure due to unexpected erosion. Recent reconnaissance surveys conducted for many completed projects have indicated that urgent intervention was required at several locations where active erosion had caused safety issues for personnel and could cause environmental and economic losses if erosion were to continue in the near future. The proposed research will develop the improved understanding required to assess and predict erosion processes of rivers in glacial tills and marine clays for built structures by characterizing the erosion process from field surveys and determining, from collected soil samples, the range and variability of standard geotechnical parameters of the materials both inter and intra-deposits. This project will help identify projects with potential design challenges due to the presence of glacial tills or marine clays, allowing for designs with a lower risk and lower costs. The increased knowledge will improve expert knowledge and train young engineers, while consulting companies will be able to bid more competitively and clients will have improved long-term management of projects with lower and more predictable costs.****************