America’s dams are aging, and in many areas heavy rain storms are happening more often. Dam engineers who have studied recent disasters say those two trends could mean more dam failures if dams aren’t repaired.
Oklahoma City’s Overholser Dam is among the nearly 3,000 U.S. dams USA TODAY identified that are in areas that get more frequent storms than in the past, are listed in poor or unsatisfactory condition and would probably kill people or destroy property if they fail.
Using photographs taken by dam inspectors and other sources, USA TODAY created a simulated flyover to highlight trouble spots.
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The U.S. Geological Survey modeled what would happen if Overholser broke during the maximum flood current standards require it to handle. By design, that standard is a rare, worst-case event, so the survey also modeled what would happen if the dam broke on a sunny day.
Think of the extremes as bookends. If the dam were to fail, the flood would occur somewhere between the sunny-day flood and the maximum flood.
Oklahoma City’s utilities department received an engineering study in September that presented a $48 million plan to fix the dam’s gates and reinforce the concrete. Utilities Director Chris Browning said design work will take until 2025. After that, the gates are scheduled to be completed in 2027 and the concrete work by 2030.
During construction, contractors are expected to build a temporary earthen dam upstream from the current dam.