Arch Engineers Ltd. designed an urgent recovery plan for a drill head stuck approximately 40 meters from its intended exit pit beneath the Clearwater River. This challenging operation required innovative engineering and rapid deployment. The team faced major constraints, including a depth of over 10 meters below grade and 7.5 meters beneath the river water level.
The recovery’s urgency stemmed from the risk of the drill head becoming permanently lodged under the constantly shifting riverbed. This risk threatened the project schedule and long-term feasibility of the crossing. Initial investigations identified a massive, previously undetected boulder as the primary obstruction. As a result, Arch had to develop a highly adaptable recovery strategy.
To meet these challenges, Arch Engineers created a flexible shoring design. This allowed field engineers to make real-time adjustments as recovery operations progressed through four defined stages. The adaptable system ensured that excavation and stabilization measures could respond to changing conditions around the drill head, despite the unknown size and position of the obstruction.
The team’s recovery plan included advanced geotechnical modeling and a robust shoring system. This system resisted hydrostatic pressures and adapted to the dynamic nature of the Clearwater River bed. By balancing speed with engineering precision, Arch successfully retrieved the drill head. This minimized delays and prevented further complications. The project demonstrated Arch Engineers’ ability to deliver innovative, adaptive solutions under extreme time and environmental constraints.