Results of Trial Grouting at Ontario Power Generation's Sir Adam Beck Pump Generating Station Reservoir, Niagara Falls-PPT Presentation

PPT Presentation

Pdf Summary

Ontario Power Generation’s Sir Adam Beck Pump Generating Station reservoir in Niagara Falls is enclosed by a 7.4 km rockfill dyke. After sinkholes and signs of seepage-related erosion were identified over several decades, OPG planned a new grout curtain to reduce seepage and the risk of piping through the foundation. The design called for a 1.2 km curtain beneath the clay core, extending the 1958 treatment and tying into low-permeability Rochester Shale.<br /><br />Before production work inside the reservoir, a trial outside the dyke tested contact grouting at the overburden–bedrock interface and staged bedrock grouting. The trial generally demonstrated that geotextile barrier bags could isolate the contact zone and that grout could fill the annulus above the bags. However, excavation revealed voids beneath some bags, and sleeve-port contact grouting appeared to have limited effectiveness. The overburden and exposed bedrock were also better quality than anticipated, with no significant sand or gravel layers; contact grouting was therefore deemed unnecessary.<br /><br />Grout takes and secondary-hole results indicated that additional, tertiary-order grouting would be needed. These findings informed changes to the production design, including retaining the bags for annulus filling, omitting contact treatment, and allowing for higher-order grouting.<br /><br />The presentation concludes that the trial reduced uncertainty and helped identify foundation conditions and necessary design changes before work began near the dyke. It recommends trial programs for similar projects and emphasizes collaboration among the owner, engineer, and contractor when revising grouting methods.

Keywords

Ontario Power Generation

Sir Adam Beck Pump Generating Station

Niagara Falls

rockfill dyke

grout curtain

seepage

piping risk

foundation grouting

trial grouting

Rochester Shale