Monday, November 28 2011 7:50 PM EST2011-11-29 00:50:11 GMT
Engineers in Georgetown cannot agree on a cause for the sinkholes in the coastal city. Early estimates have damage totals reaching hundreds of thousands of dollars.More >>
GEORGETOWN, S.C. (WCIV) – Fourteen months after several sinkholes damaged buildings and caused traffic problems in Georgetown, a consulting firm has released their findings on what caused the sinkholes to form.
According to a report from Foundation and Materials Engineering Consultants, a geotechnical engineering firm based out of Columbia, construction in an area made up of fossiliferous marine limestone is the culprit.
The report says that the area is a "karst" which has "solution cavities and is subject to sinkholes or depressions." It also says the primary cause of the sinkholes was the installation of "king piles" for the City Hall Storage Facility that penetrated the water table, allowing water to come up out of the ground.
Once the water table had been punctured, the report says an "accelerating factor" was the pumping the construction crews did to get rid of the water that had come up.
The report also points out that the problem had been building since the first depression showed up in July 2011 - four months before massive sinkholes destroyed Parrish Place, a business plaza on North Fraser Street.
The report says the initial depression was reported July 14, 2011, on Hazard Street. The South Carolina Department of Transportation thought it was caused by a leaking utility pipe so they filled the depression with sand and covered it in asphalt.
F&ME reports when the depression happened again in the same spot, they took a look at city utility plans, realized there was no pipe under the depression and covered it up once again.
According to the report a third depression happened at Parrish Place in October 2011, but no mention is made of what they did to remedy the situation. A month later, Parrish Place was brought down by a sinkhole and two more formed on Prince Street and under the Bank of America.
The report does point out, however, that Georgetown was not "known as being underlain by karst terrain" but that a sinkhole did appear in the area 60 years ago.
Since the information about the cause of the sinkholes came to light, at least one business has launched a lawsuit against the city for damages. Other affected businesses have said they plan to file lawsuits as well.
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