Tag Archives: Army Corps of Engineers

More on Dam Problems for Harris County

The Barker and Addicks Reservoirs are reaching historical levels after the recent rains in Harris County.   For the first time ever, the National Weather Service has issued flood warnings for both reservoirs.  The Army Corps of Engineers also released a statement warning residents living behind the reservoir to be ready for flooding.

The water level in the Addicks Reservoir was measured Wednesday night at 101.4 feet and is expected to crest at 103.2 feet, surpassing the previous record for the reservoir of 97.46 feet set in March 1992. The Barker Reservoir was 93.8 feet and expected to crest at 97.7 feet, also exceeding the March 1992 record of 93.6 feet.

Officials say the dams are not expected to reach 100 percent capacity.  However, part of the reservoirs are on private property.  If the water levels rise more than anticipated, area roadways and some subdivisions will be flooded.

Harris County Judge Ed Emmett said officials are considering acquiring sandbags for deployment on “non-governmental land” behind the Addicks and Barker reservoirs due to the potential flooding of homes.

A Big Dam Failure in Houston?

In fall 2009, the U.S. Army Corps of Engineers tagged West Houston's Addicks and Barker dams with an "extremely high risk of catastrophic failure" label. According to the Corps, the 1940s-era dams, which leaked in April 2009, are two of the country's six most dangerous. As a result, the Corps, during an abnormal weather event, might be forced to release more rainwater downstream, which could send Buffalo Bayou out of its banks and flood homes in Memorial and Tanglewood.

With more rain on the way, nervous Houstonians may not even be aware that two aging dams stand between them and catastrophe.  It’s not a new problem.  Check out Steve Jansen’s article in a July 2012 edition of the Houston Press.   As if you didn’t have enough to worry about.

Addicks and Barker have also been weakened due to the natural decline of dams that are made out of a big pile of dirt. According to a 2010 study released by the United States Society on Dams, soil and rocks that have been used in dam construction tend to deform, erode and lose strength over time.

As a result, Houston’s most valuable and proven flood-control mechanisms might not be able to protect the city against a 25-year storm event, says Lawrence Dunbar, a former head of the Army Corps of Engineers’ flood control and reservoir regulation section in Chicago.

“The Corps isn’t quite sure how these voids got formed. Therefore, they’re not sure if you get another big rain and the reservoir fills up again, even if it doesn’t get high as it got before, they’re not sure it can hold and voids won’t form again,” says Dunbar, a licensed professional engineer in Texas since 1983.

In the 1980s, the Corps installed concrete walls inside the earthen part of the dam to discourage leakage. However, the concrete wasn’t installed above or below the culverts, which need replacing in the worst way.

“That’s where they found these voids — under the culverts,” says Dunbar. “What happens when a void forms is, it can basically let water blow through under the culverts or through the dam. When that happens, it’s bad and dam failure is imminent. It’s a big concern,” says Dunbar.