IDENTIFYING ABANDONED COAL WORKINGS USING GEOPHYSICS

2017

Mr Drew Fossen (Geophysicist - DMT Geosciences Ltd.), Dr Jane Dawson (Sr. Geophysicist - DMT Geosciences Ltd.), Mr Rob Perrin (Sr. Geophysicist - DMT Geosciences Ltd.)

Case studies are presented from multiple sites located in Alberta, where previous coal operations occurred. In order to reduce the risk of an event happening, geophysics was used to help identify potential geotechnical hazards. The first case study was located near a rail line, busy highway, a construction site, power lines, and drilling activities that added significant sources of noise for seismic surveys. This, combined with the shallow nature of the coal mining operations, made for a challenging seismic survey. For this reason, the survey design included combining three seismic methods to optimize the chance of successfully identifying potential hazards: seismic reflection, seismic refraction and multi-channel analysis of surface waves (MASW). These survey results were integrated with available borehole information and historic records of the coal workings. In some situations direct detection of coal workings can be challenging for a variety of reasons. In these cases, it is the secondary effects of coal workings that may be more readily detectible using geophysics. We present a study from Canmore, Alberta in which geophysics was used to map secondary coal working structures in 3D and so triangulate the expected location of an air shaft.
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