Cityscapes: When Soil Subsidence Hits Home, Suburban Houses Explode

Feb 20, 2015

In this month's Cityscapes column at Nola.com, Tulane Professor of Geography Richard Campanella explores some very real consequences of draining urban wetlands for building.

A horrifying string of deadly explosions hit Metairie homes in the 1970s. It turned out soil subsidence was to blame. The drying, settling and cracking of the land beneath the former swampland snapped gas lines, filling the houses with invisible, flammable gas. "And then someone would come home, plug in a toaster oven, light a cigarette, and the whole house would explode," Campanella says.

(For more on terms like "subsidence," see our WWNO Coastal Glossary.)

Where do we go from here? He notes we cannot re-inflate urban soils, but Campanella says, "We can make an effort to keep them as wet as possible, by slowing down runoff, storing as much as possible on the landscape to re-charge that groundwater."

Fifty percent of the city currently sits below sea level, he says, mostly due to the drainage of urban wetlands. Smarter planning going forward is vital, he says.

"One lesson we can take away is that we should think long and hard before erecting more levees and draining more areas on this deltaic plain, so that we don't repeat this."