Anthropogenic Impacts on Groundwater and Slope Stability; a Case History

Wayne Clifton

In the proceedings of: GeoRegina 2014: 67th Canadian Geotechnical Conference

Session: Landslides and Geohazards

ABSTRACT: genic Impacts on Slope Stability and Railway Safety Wayne Clifton, P.Eng. Clifton Associates Ltd., Regina, SK, Canada Chris Bunce, P.Eng. CP, Calgary, AB, Canada ABSTRACT Railways and other linear corridors are in fixed locations and can be subject to adverse impacts due to changes in the physical environment resulting from nearby human impacts; this is a case history of such an occurrence. The CP rail line between Fort Steele and Cranbrook, BC was constructed along the valley slopes of the St. Maryin 1969 to 1970 to facilitate development of dams on the Columbia River. The route traversed stable, well-drained, glaciated terrain comprised of a drumlinized till plain interspersed with glacio-fluvial-lacustrine deposits between Mile 98 and about Mile 99.8 where local bedrock outcropped at track level. Subsequent construction of wastewater ponds 3.4 km upslope from Mile 99.0 impacted the groundwater regime, causing landslides along the CP track. Complex, multidisciplinary investigations were undertaken to demonstrate the cause and magnitude of these anthropogenic impacts. RÉSUMÉ Les voies ferrées et les autres corridors linéaires occupent des positions stationnaires et peuvent être sujets à des impacts défavorabavoisinantes ; une telle histoire de cas sera documentée ici. Le chemin de fer du CP entre Fort Steele er Cranbrook (CB, Canada) a été construit sur les pentes de la vallée de la rivière St. Mary en 1969 et en 1970 afin de faciliter le développement des barrages sur la rivière Columbia. Entre le Mille 98 et aux environs du Mille 99.8, le tracé passait sur es drumlins, entrecoupée de dépôts fluvio- km en surplomb vis-à-t des eaux souterraines, entraînant des glissements de terrain le long de la voie du CP. Des études multidisciplinaires 1 INTRODUCTION Linear facilities such as pipelines, roads and railways occupy a fixed location on the landscape and, typically, cannot be relocated when threatened by terrain-based hazards such as landslides, debris avalanches or other forms of instability that could damage a facility. Soil mechanics theory demonstrates that any rise in the water table will reduce the factor of safety of a slope with respect to slope stability. Consequently, operators of linear facilities are sensitive to upslope activities such as deforestation, changes in drainage or construction of water storage ponds that could reduce the stability of slopes and increase risk to their operations. Landslides are a concern to these operators not only because of potential damage to equipment and infrastructure but in the case of railways and roads, out of concern for safety of employees and the public respectively. The railway track of the CP Cranbrook Subdivision between Fort Steele and Cranbrook, BC is constructed partially in cut and partially in fill along the steep valley walls of the St. Marylocation of the route and the mileage between Mile 98.0 and Mile 99.7 is shown on the oblique photograph (Figure 2). The track provides a vital international link and also serves important industries in the region. Figure 1. Location Plan of CP Track between Fort Steele and Cranbrook, BC

RÉSUMÉ: hropogenic Impacts on Slope Stability and Railway Safety Wayne Clifton, P.Eng. Clifton Associates Ltd., Regina, SK, Canada Chris Bunce, P.Eng. CP, Calgary, AB, Canada ABSTRACT Railways and other linear corridors are in fixed locations and can be subject to adverse impacts due to changes in the physical environment resulting from nearby human impacts; this is a case history of such an occurrence. The CP rail line between Fort Steele and Cranbrook, BC was constructed along the valley slopes of the St. Mary

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Cite this article:
Wayne Clifton (2014) Anthropogenic Impacts on Groundwater and Slope Stability; a Case History in GEO2014. Ottawa, Ontario: Canadian Geotechnical Society.

@article{GeoRegina14Paper475,author = Wayne Clifton,title = Anthropogenic Impacts on Groundwater and Slope Stability; a Case History ,year = 2014}