Rehabilitating Hardy Dam for Stability and Seepage Control

R. Kenyon, J. Mann, C. Robak, K. Brown

In the proceedings of: GeoOttawa 2017: 70th Canadian Geotechnical Conference; 12th joint with IAH-CNC

Session: Dams and Embankments

ABSTRACT: The Hardy Dam, located 5 km north of Atikokan, off of Highway 622, in northwestern Ontario, was constructed over Hancock Creek in 1957 as one of the water control structures of the former Steep Rock Mine. Since the dam™s construction, the north slope of the original Hancock Creek channel near the north abutment was subject to ongoing seepage and blowouts. Reverse filter granular toe berms were constructed in the area, but a groundwater depressurization system was ultimately required to control the seepage related instability. Two dimensional finite element based seepage / slope stability models were developed for the north abutment and the main dam. The modelling demonstrated that the north abutment was analytically unstable under high flowing artesian conditions that existed prior to the implementation of the depressurization system. The modelling also confirmed that the dam met specified criteria with respect to slope stability despite flowing artesian groundwater pressures at the dam™s toe.

RÉSUMÉ: Le barrage Hardy, situé à 5 km au Nord d™Atikokan, à proximité de l™autoroute 622, dans le Nord-Ouest de l™Ontario, a été construit sur le ruisseau Hancock en 1957 comme une des structures de contrôle d™eau de l™ancienne mine Steep Rock. Depuis la construction du barrage, la pente nord du canal initial du ruisseau Hancock, près du pilier nord, était continuellement soumise aux infiltrations et aux éruptions d™eau. Malgré la construction de risbermes granulaires à filtration inversée dans la région, un système d™assèchement des eaux souterraines était nécessaire afin de contrôler l™instabilité de la pente nord due à l™infiltration des eaux. Des modèles de stabilité de pente et d™infiltration d™eau à deux dimensions à base d™éléments finis ont été développés pour le pilier nord et pour le barrage principal. La modélisation a démontré que le pilier nord était instable dans des conditions artésiennes élevées avant la mise en œuvre du système d™assèchement. La modélisation a également confirmé que le barrage répondait aux critères spécifiés en ce qui concerne la stabilité de pente, malgré la pression artésienne qui se manifestait au pied du barrage.

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Cite this article:
R. Kenyon; J. Mann; C. Robak; K. Brown (2017) Rehabilitating Hardy Dam for Stability and Seepage Control in GEO2017. Ottawa, Ontario: Canadian Geotechnical Society.

@article{geo2017Paper761,author = R. Kenyon; J. Mann; C. Robak; K. Brown,title = Rehabilitating Hardy Dam for Stability and Seepage Control,year = 2017}