A decade of monitoring the landslide on a highway crossing in the Frenchman River Valley in Saskatchewan

Hung Vu, Hamid Soleymani, Harpreet Panesar, Laurie McEachern

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

Session: Instrumentation and Monitoring

ABSTRACT: f monitoring the landslide on a highway crossing in the Frenchman River Valley in Saskatchewan Hung Vu1, Hamid Soleymani2, Harpreet Panesar2 and Laurie McEachern1 1Golder Associates Ltd., Saskatoon, Saskatchewan, Canada 2Ministry of Highways and Infrastructure, Regina, Saskatchewan ABSTRACT Massive landslides occur in southern Saskatchewan. Natural slopes across some glacial valley walls may have failed in the past and are susceptible to movement with slight changes in slope geometry and/or change in groundwater conditions. A landslide on Provincial Highway No. 37, crossing the Frenchman River Valley, was activated in 2003 by fill placement during the realignment of the highway. Remedial construction was completed in 2004. Both piezometric levels in the slope and slope movement have been monitored since the landslide occurred. This paper presents geological and hydrogeological conditions, discusses the results of the instrumentation monitoring program, and provides an update on the groundwater and slope stability conditions of the landslide at Highway No. 37 crossing the Frenchman River Valley. RÉSUMÉ Des glissements de terrain massif sont trouvés dans le sud de la Saskatchewan. Les pentes naturelles à travers des parois de la vallée glaciaire ont peut-être échoué dans le passé et sont susceptibles de mouvement avec seulement une modification mineure de la géométrie de la pente et/ou de l'état des eaux souterraines. Un glissement de terrain sur la route provinciale numéro 37, traversant la Vallée de la Rivière Frenchman, a été activé en 2003 par le placement de sol pendant le ré-alignement de la route. La construction réparatrice a été complétée en 2004. Les niveaux de piézomètre dans la pente et le mouvement de la pente ont été surveillés depuis que le glissement de terrain. Ce document présente les conditions géologiques et hydrogéologiques, discute des résultats du programme de surveillance des instrumentations et fournit une mise à jour sur les eaux souterraines et la condition de stabilité de la pente du glissement de terrain à la route 37 traversant la Vallée de la Rivière Frenchman. 1 INTRODUCTION The terrain in southern Saskatchewan is dominated by glacial deposits and erosion. During glacial deposition, both ice and melt water deposited a variety of sediments called till (ice deposition) and Surficial Stratified Deposits (meltwater deposition). The composition of till and stratified deposits ranges from clays and silts to sand and gravels depending on the bedrock material. Erosion, subsequent deposition and deformation by the process of ice-thrusting and meltwater flow can significantly affect the stratigraphic interpretation and engineering properties of sediments. Glacier ice thrusting and meltwater flow resulted in deformation and shearing of bedrock clay and glacial sediments is widespread throughout southern Saskatchewan. Hydrogeology of this region is also complex. Flowing artesian conditions are encountered in some areas at lower elevations along riverbanks or valley slopes. The stratigraphy and hydrology of overlapping sediments produced by repeated glaciations contribute significantly to stability problems due to seepage or significant changes in material properties that occur between stratigraphic contacts. Massive slope failures or landslides occur in southern Saskatchewan. Natural slopes across some glacial valley walls and river banks may have failed in the past and are presently at or near equilibrium. These slopes are susceptible to movement with slight change in slope geometry (e.g., erosion or fill placement) and/or change in groundwater condition. The most common slip planes of slope failures are found to be near horizontal in low shear strength materials such as a bentonite layer, a pre-sheared zone in bedrock clay shale or in the highly plastic clay of the Surficial Stratified Deposits at the contact with the till. The failures may involve retrogressive, multiple and/or multilevel failures that result in complex deformation patterns where components of the failures are moving at different rates. The landslide that recently occurred on Highway No. 37, crossing of the Frenchman River Valley, is one of such landslides. This paper presents geological and hydrogeological conditions of landslide site, discusses the results from a decade instrumentation monitoring program, and provides an update on the groundwater and slope stability condition of the landslide at Highway No. 37 crossing at Frenchman River Valley. 2 OVERVIEW OF THE LANDSLIDE AT HIGHWAY 37 CROSSING Provincial Highway No. 37 crosses the Frenchman River Valley approximately 30 km south of Shaunavon, Saskatchewan (Figure 1). The formation and geological conditions of the valley are presented in Christiansen and Sauer (1998). The Frenchman Valley is approximately

RÉSUMÉ: ade of monitoring the landslide on a highway crossing in the Frenchman River Valley

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Cite this article:
Hung Vu; Hamid Soleymani; Harpreet Panesar; Laurie McEachern (2014) A decade of monitoring the landslide on a highway crossing in the Frenchman River Valley in Saskatchewan in GEO2014. Ottawa, Ontario: Canadian Geotechnical Society.

@article{GeoRegina14Paper276,author = Hung Vu; Hamid Soleymani; Harpreet Panesar; Laurie McEachern,title = A decade of monitoring the landslide on a highway crossing in the Frenchman River Valley in Saskatchewan,year = 2014}