The performance of the Waba Dam under changing foundation conditions

Abstract

The Waba Dam is an embankment dam that was constructed on sensitive marine clays located approximately 60 km west of Ottawa, Ontario in the period between 1973 and 1976. At approximately 18 meters high, it was the largest dam ever constructed on a Leda clay foundation at the time. Significant settlement was anticipated, and, to date, the dam has settled about 1.8 meters – almost exactly in line with original design predictions. Recent investigations show that primary consolidation is still occurring 43 years after construction and will continue to occur over the coming centuries. This paper holistically examines the monitoring data and investigation results collected during and after construction with a focus on new information from the past decade in order to present a never-before-studied look at the foundation directly beneath the highest portion of the dam. Changes in soil strength, settlement, pore pressures, and deformation over time are viewed with respect to how these influences impact the dam’s stability, settlement, and overall performance, as well as dictate requirements for future rehabilitation to ensure the continued safe operation of this unique dam.