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Case Study

Geophysical investigations for coastal gaslink pipeline

pipe running through dirt walls

In 2014, the Advisian Geophysics and Geotechnical teams began working together to delineate areas of potential glaciomarine clays as part of the Coastal GasLink Pipeline Project. Sensitive glaciomarine clays pose a geohazard to pipelines due to their low shear strength.

Approach

Electrical Resistivity Tomography (ERT), seismic refraction surveys, and MASW (Multi-Channel Analysis of Surface Waves) were conducted along the proposed pipeline Right-Of-Way (ROW). The seismic refraction data were processed for P-wave velocities (to delineate bedrock) and for MASW shear wave velocities. Potential glaciomarine deposits were identified by analysing results from all three surveys.

Based on the geophysics results, a follow-up borehole and cone penetration test (CPT) survey was designed by the geotechnical team.

Results

The integration of non-intrusive geophysical data into the geotechnical assessment increased confidence in the interpretation of borehole data and generated significant cost savings in the form of reduced drilling costs. This combined approach also provided the client with a clear understanding of the location of potential glaciomarine clays along the proposed ROW.

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