Sinkhole in Allentown, Pennsylvania

Published on January 10th, 2012 | by

A sinkhole in Allentown, Pennsylvania opened up in the last week of December, taking several houses with it and exposing a broken water main. Experts are undecided as to whether the cavern broke the water main or if the water main broke and caused the sinkhole.

Many residents are homeless for the time being, either living with friends and family or staying in shelters. The city had put some residents into a hotel, but that arrangement ended a week ago.

What Is a Sinkhole?

A sinkhole is basically a collapsed cave. Caves are often formed by water moving through softer rocks, like salt, gypsum, anhydrite, limestone, or dolomite, and dissolving them.

It can take a thousand years or it can take a day, depending on the geology and flow and pressure of the water.

Once the cavern is formed, its stability depends on the strength of the rock above the cavern. If the rock is thick and the cavern is deep underground, people living above the cavern might never know it exists.

The roof of the cavern can also be held up by the pressure of the water within the cavern. When aquifers close to the surface are drained, caverns can collapse and become sinkholes.

What Happened in Allentown?

A sinkhole about 50 feet long and 30 feet opened up on Thursday before New Year’s and another sinkhole was discovered on Friday. Residents said water flooded their basements before the sinkhole opened up.

A gushing water main was found in the sinkhole, but authorities have not stated whether the water main was a cause or effect of the sinkhole.

Why does it matter if it’s cause or effect? The residents who have been affected by the sinkhole have lost their houses. The sinkhole didn’t swallow the homes, but it affected the structural integrity and many will have to be condemned.

If the damage to the homes was caused by a naturally occurring sinkhole, which then broke the water main, the homeowners can receive assistance from disaster agencies. Neither the Red Cross nor FEMA had shown up to offer help earlier this week because the sinkhole was not declared a natural disaster.

If the damage was caused by the broken water main, then the utility district would liable. This would be an expensive lesson for the district.

Leaking Pipes and the Nation’s Infrastructure

Whichever cause is eventually pinpointed by the investigation, repairing and replacing old pipes might have prevented this disaster.

Repairing and replacing leaking pipes throughout the nation could help prevent sinkholes from opening up in other places. Preventing the water leaks would prevent the sinkholes from forming in the first place. Sometimes, though, utility workers will find that the ground has shifted or opened up when they go to replace a pipe and a new engineering plan might need to be laid out.

35-40% of the United States is built over sinkhole-prone formations. Tight budgets keep many places from updating their infrastructure.

Fixing pipes now can be done for a fraction of the cost of cleaning up condemned houses and fixing the pipes later. Refusing to fix the nation’s water infrastructure because of tight budgets is pennywise and pound foolish.

Image of map sinking via Shutterstock


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