Investigation of Geophysical Methods for Assessing Seepage and Internal Erosion in Embankment Dams: Engineering Seismic Surveys at a Test Embankment Near Seven Sisters, Manitoba

The objectives of this work were to research seismic methods and develop techniques to locate seismic anomalies in embankment dams. A test embankment was constructed with medium and high plastic clay in October 1999 near Seven Sisters, Manitoba to facilitate the project. Three seismic targets, composed of coarse rock wrapped in geotextile, were constructed in the high plastic clay foundation beneath the test embankment. Refraction and reflection seismic surveys using a variety of sources, detectors and collection geometries were used to locate the targets. The P-wave refraction survey results defined the bedrock surface, but did not indicate the presence of the targets. The P-wave reflection surveys did not define the bedrock surface or locate the targets. Results from the SH-wave reflection surveys showed the bedrock surface and anomalous responses were observed in the areas of the targets. This volume marks one of a series of reports on the subject of geophysical methods and their use in assessing seepage and internal erosion in embankment dams.