Case Study: Vermilion Dam Trunnion Bearing Pad Structural Repairs and Waterproofing

Aqua Water made the decision to rejuvenate the existing dam of Lake Vermilion. This dam is vital to the community because it supplies their drinking water. The dam consists of 13 gates and an overflow. The gates are remotely raised or closed to control the water supplied to the Vermilion River. The water travels about a mile downstream to the water treatment plant to be processed and supplied to the community.

The Concrete Restoration Group was hired as a subcontractor to perform repairs to the cracks at critical points of the structure. Structurally, the engineer’s area of concern were the trunnion bearing seats. The trunnions raise and lower the large gates and the support seats needed to be structurally sound. Before construction could start, documentation was provided showing experienced work history of similar repairs. Once onsite, the areas were assessed and specific repair areas were dictated by the onsite engineer. Over 6 mobilizations were necessary to make the epoxy injection repairs because access to the work was challenging.

As with most restoration projects, unforeseen challenges presented themselves. As new gates were installed the seals riding along the sill plate began to leak. Upon further inspection it was discovered that, when the gates were lowered, water was rushing through additional cracks in the concrete behind the sill plate, not between the rubber seal gaskets as originally thought. Since the new gates were already installed removing the seal plates from the concrete piers and resetting them would have been extremely costly. CRG was up to the challenge of stopping the new water flow from behind the plates. A hydrophobic polyurethane grout mixed with an accelerator was injected behind the leaking sill plates. Success of the repair was immediately evident as a reaction it was noticed seeping out of the concrete 18” away from the injected location! This was proof that the material thoroughly penetrated the porous concrete. The areas were cleaned up and the seals were reset.

The Concrete Restoration Group drastically improved the water intrusion water intrusion drastically improved.