Six years ago this month heavy rains caused leaks at the Lake Needwood Dam, in Montgomery County, forcing the evacuation of thousands of nearby residents. The feds hailed the response as exemplary, and they are using the anniversary to unveil new dam safety programs.
More than 2,000 people had to be evacuated when the dam started leaking following several consecutive days of heavy rains in 2006. The earthen dam itself was never breached, mostly because the leaks were occurring in rocks beneath the structure. Mike Riley, the engineer of record for the dam at the time, says the fixes were made quickly.
"Grouting, which is nothing more than injecting a form of cement down into the bedrock underneath the dam through very small but deep holes that were drilled," says Riley.
He says the whole scene proves one of the biggest themes of dam safety: better safe than sorry.
"Once we determined it was coming through the rock you could argue there was never a threat of breach or loss of life downstream," he says. "But the problem is you don't know when you see the leak."
Officials with the Federal Emergency Management Agency announced at Lake Needwood their new plans to stop dam failures nationwide on the 123rd anniversary of the Johnstown Flood, the third worst natural disaster in U.S. history in terms of lives lost. It was caused by a dam failure.