Two hyperbolic concrete cooling towers serving a steam electric generating station were put into service in 1972 and 1973. By 1985, they exhibited significant deterioration, corrosion of embedded steel, and water leakage through the shells. These massive towers, which topped out at 370 feet above grade, and were as large as 248 feet in diameter, were essential to the plant's operation. They would need major repairs, which could be carried out only during scheduled outages in order to avoid disruptions in the area's power supply.

Scheduling repairs was only one of the project's challenges. Providing access to the interior and exterior of the towers to allow thorough inspection and repair was difficult. Careful structural analysis was required to maintain structural integrity while repairs were under way. Additionally, repair materials had to be evaluated and selected for their ability to withstand the unusual conditions within the towers.

To meet these challenges, the power company assembled a multi-disciplinary team comprised of civil engineers, concrete material and construction consultants, structural engineers, and specialists in testing and evaluation.

Using visual inspection, hammer sounding throughout both towers, and laboratory testing of core samples, investigators identified the types and amount of concrete deterioration. In addition to the spalling, corrosion, and leakage already noted, they found cracks in the support columns and ring beams at the base of each towers.

Repair crews removed the deteriorated concrete from the tower shells with pneumatic chipping hammers and filled the voids with dry-mix shotcrete. They sealed cooling tower interior surfaces with a waterproof and vaporproof epoxy coating. The cracks in the supporting columns and ring beam were cleaned and sealed with epoxy.

Meticulous quality control testing and inspection during repairs helped ensure the project's success and significantly extended the towers' service life.