Soo Asset Renewal – Crib Dam Stabilization

The Crib Dam adjacent to the New Power Plant (NPP) at Soo Locks, Sault Ste Marie, MI, has been a critical safety concern for years, with the first significant repair occurring in 2011. This repair involved the replacement of the most vulnerable portion of the timber structure with a concrete L-wall, addressing immediate risks but not fully resolving all dam safety issues.

As part of a comprehensive plan to ensure long-term safety and operational efficiency, a new design has been developed to address these lingering concerns. This design involves the installation of a 300-foot combination pile wall along the north face of the crib dam. This hybrid wall, consisting of steel pipes and sheet piles driven 12 feet into the rock, will be reinforced with tremie concrete between the existing crib dam and combination wall to prevent seepage. This design will enable operations to provide support for heavy crane loads and other operational demands.  The project’s current working estimate was estimated to exceed the project budget by almost double.

The Value Team addressed significant constructability challenges, including site access and coordination with ongoing construction activities for the New Lock Chamber project.  The Value Team’s Function Analysis of the project led to a paradigm shift in the Value Team and Design Team’s understanding of the project.  At the commencement of the Value Study, it was communicated that the goal of this project was to stabilize the crib dam to increase operational safety.  During the Value Study, the Value Team came to an understanding that the overall purpose of this project was really to support powerplant operations.  This new understanding came from a question from the Value Team to the Design Team, asking “If the crib dam were to fail, but the channel directing water to the power plant intake was maintained without impeding on power plant operations, would the project still be successful?”.  The Design Team confirmed that the following scenario would result in a successful project.  The Value Team, tasked with optimizing the project design, identified the key project functions—Contain Water, Ease Construction, and Support Loads—as essential to achieving a successful outcome to maintain the existing channel supporting power generation at the NPP.  From there, the Value Team’s identified functions and new understanding of the project guided the team in identifying solutions that shifted focus to the longevity of the new wall and areas of the existing dam that were critical to supporting power plant operations.  The Value Study resulted in an accepted cost avoidance to the project of approximately 40% of the project cost, bringing the project back within budget.

This project represents a critical investment in the safety and reliability of our hydroelectric infrastructure, reinforcing the commitment to sustainable and resilient power generation for the future.