Sinkhole Severs Sewers, Wipes Out Lift Station

A stormwater culvert collapses, creating a 45-foot-wide sinkhole — and a $500,000 problem — in Texas
Sinkhole Severs Sewers, Wipes Out Lift Station
The washout of a stormwater culvert — estimated to be between 40 and 50 years old — was blamed for a 45-foot wide, 30-foot deep sinkhole in Granbury, Texas in early May. (credit: City of Granbury)

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Public Works officials at the City of Granbury (Texas) are surveying the damage left behind by a 45-foot-wide, 30-foot-deep sinkhole in the parking lot of a local grocery store after heavy rainfall washed out a stormwater culvert. Sewer lines that were attached to a nearby lift station were severed, and the lift station itself is a total loss.

"We discovered the cause of the washout was that an 8-foot stormwater culvert, running under the parking lot and sitting lower than the lift station, had collapsed," says Sheri Campbell-Husband, assistant city manager. "With all the recent rain, the water had to go somewhere, and it leaked out of the blocked culvert, saturating the ground beneath the lift station and causing a complete washout."

She says a small amount of wastewater was also discharged into Lake Granbury. The Granbury City Council met in an emergency session on Sunday, May 10, to declare a local disaster and clear the way for immediate repairs. 

"City crews were able to cap those sewer lines quickly and divert the gravity flow around the site, back into the system on the other side," Campbell-Husband says. "No ill effects were experienced by any customers and the amount of raw sewage going into the waterway was relatively minimal."

The full extent of the damage is not yet known, however, in part because rain impeded the progress of work crews at the site throughout the week. Officials estimate the cost of repairs at around $500,000, according to a report by the local CBS affiliate.

Campbell-Husband says the city doesn’t know how long ago the culvert collapsed, but the infrastructure was between 40 and 50 years old. North Texas has already received more rainfall than average this month. Granbury, located about 25 miles southwest of Fort Worth, received 5 to 8 inches of rain over the weekend the sinkhole opened.

Engineers and contractors are working on a strategy to either repair or replace the stormwater culvert, "then they'll help us develop a plan for stabilizing and filling the hole so a new lift station can be constructed." There's currently no solid timetable for the work to be completed.



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