Bradley: Dams will continue to fail until we require owners to upgrade

As the former S.C. dam-safety program hydrologist, I would not be surprised to learn that most of the dams that failed in the October deluge had inadequate spillway capacities. Because they were grandfathered into regulation when the dam safety program was created in the 1970s, they only had to meet the spillway-capacity requirements if substantial repair was performed. In retrospect, this seems to have been too lenient an approach to ensure the safety of downstream densely urbanized areas and the public infrastructure and its users.

Properly constructed roller-compacted concrete provides protection against overtopping, which is the leading cause of dam failure; other construction methods for overtopping protection are being used throughout the world. The Forest Lake Dam was overtopped and did not fail, as it was protected by the cable-stayed concrete armoring of its upstream, top and downstream slopes.

DHEC has promised to increase staffing for the dam-safety program; it also should realistically assess the salary structure. In the past, the federal government has provided extensive technical training for dam-safety engineers, but many have left for better-paying jobs with local governments or private industry.

No additional regulation and staffing, however, will remedy the problems unless owners are required to upgrade their dams to meet the engineering-stability requirements.

Owners who contacted me when I worked with the program were genuinely concerned about their dams, but convincing them of their potential liability was very difficult. Insurance, unfortunately, is not available for privately owned dams, but if it were, the owners would have a value placed on their dams’ stability and failure consequences, which would motivate them to operate the dams more responsibility or else remove them.

In October of 1990, when the Klaus-Marco tropical storm complex dumped extreme precipitation amounts in the Kershaw County area, four people drowned when their car was washed off of U.S. 1 in Camden; their deaths were blamed on the failure of the Kendall Dam.

Where and when will the next extreme rainfall event occur? Will we be more safety conscious and not attempt to drive through flooded roadways? Will our dams be safer and more stable? Have we learned anything from our experiences?

This story was originally published December 27, 2015 at 3:55 PM.