Complex Logistical Constraints and their Technical Impact on A Deep Excavation Design, Ottawa, Ontario, Canada-Video

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The presentation details shoring for Ottawa’s Confederation Line Parkway Tunnel, focusing on a complex excavation beside the river where geology changed sharply. Water-sensitive Leda Clay required a watertight cutoff in one section, leading to secant piles and internal bracing; adjacent ground allowed dewatering and a more economical soldier-pile-and-lagging system. A skewed high-pressure gas line and electrical duct bank, phased construction, and pandemic-era material shortages complicated the design. The team used staged micropiles, concrete diaphragm slabs, utility-support beams, and carefully sequenced bracing to build around the services and tunnel formwork. The tight work area took about 18 months to resolve.

Keywords

Ottawa Confederation Line

Parkway Tunnel

shoring excavation

Leda Clay

micropiles