When the City of Columbia needed to improve the raw water intake along the Congaree River, the first engineering challenge wasn’t inside the canal. It was controlling the river itself long enough to build safely.
Stiver Engineering was engaged to design an earthen cofferdam for the Resilient Water Supply Project at the Columbia Canal Raw Water Intake in Columbia, South Carolina. The cofferdam would create a stable, dry work environment adjacent to the Congaree River, allowing construction crews to execute critical water infrastructure improvements safely and efficiently. Getting that design right required a precise evaluation of berm geometry, slope stability, and material properties before a single cubic yard of fill was placed.
What a Cofferdam Actually Requires
A cofferdam is a temporary structure, but temporary does not mean forgiving. It must hold back water and maintain structural integrity throughout the construction window. If the geometry is wrong, if the slopes are too steep, or if the material properties are mischaracterized, the structure fails. And on a project tied to a municipal water supply, failure is not an abstract engineering concern.
Stiver Engineering’s scope included evaluating berm geometry, conducting slope stability analysis, and assessing the material properties of available fill to ensure the cofferdam would meet required safety factors under project-specific site conditions. Established design methodologies were applied throughout, with the goal of producing a configuration that was not only structurally sound but constructible by the field teams executing the work.
That last point matters. A cofferdam design that is technically valid but difficult to construct in field conditions introduces risk at the point where engineering meets execution. The design had to work on paper and in practice.
Temporary Works and Long-Term Infrastructure
Temporary works like cofferdams rarely get the attention of the permanent infrastructure they enable. But without them, the permanent work doesn’t happen. The Columbia Canal Raw Water Intake is a critical component of the city’s water supply system. Any improvement to that infrastructure depends on the ability to create a safe, controlled construction environment first.
The Resilient Water Supply Project reflects the kind of long-term infrastructure investment that municipalities across the country are undertaking as aging water systems require rehabilitation, expansion, or increased redundancy. Water supply resilience isn’t achieved in a single project, but each well-engineered improvement extends the reliability and capacity of the system serving the public.
Why This Work Requires Specialized Expertise
Hydraulic structure design at the interface of active waterways demands a specific combination of geotechnical understanding, hydraulic analysis, and practical construction knowledge. Slope stability analysis requires accurate characterization of both the fill material and the hydraulic conditions the structure will face.
This project highlights Stiver Engineering’s capabilities in temporary works and hydraulic structure design, two areas that are foundational to infrastructure work near waterways and essential to projects involving water intake, conveyance, and treatment facilities. The engineering that supports a community’s water supply has to be precise, constructible, and built to perform under the conditions that actually exist in the field.
The Columbia Resilient Water Supply Project is one example of that work in practice.
