Lake Padgett, Land O' Lakes: The Sinkhole That Was Measured From the Inside

The hole started out about the size of a small swimming pool. By the end of Friday, July 14, 2017, it had swallowed a boat, pulled down two houses in the Lake Padgett Estates subdivision, and forced officials to evacuate residents from about a dozen homes. County officials measured its widest point at 260 feet. Some early accounts put it at more than 200 feet wide and 50 feet deep. When it stopped, Pasco County condemned seven homes on Ocean Pines Drive.

Lake Padgett is a 180-acre private lake in Land O' Lakes, one of the resident-only lakes at the center of the estates. The rule there has always been strict: you can't launch a boat without owning a home on the water. In 1999, when a motorsports company ran organized events on these closed lakes, its general manager, Tom Storey, said the events let people onto lakes that are usually closed.

Lake Padgett Estates sits between two large groundwater well fields. Sinkholes in this part of Florida form where acidic groundwater dissolves the limestone under the surface, hollowing out cavities until the sand and clay above lose their support and collapse. The well fields on either side of the neighborhood made it a natural place to ask whether pumping had pulled the ground down. The Southwest Florida Water Management District's readings at the closest well to the neighborhood showed groundwater levels within a normal range on the day the sinkhole developed.

Geologists came to study it. One of them was Dr. Lori Collins, co-director of the University of South Florida Library's Digital Heritage and Humanities Collections. Collins scanned the sinkhole in 3D with the same equipment her group uses on archaeological sites and historic structures, capturing its exact shape before it changed again. The hole had gone from swimming-pool size to 260 feet across in a matter of hours, faster than anyone could measure it by hand. The scan fixed the walls, the depth and the shape of the break into a record researchers can compare against the next collapse.

What Collins recorded was the geometry left behind after the boat and the houses were gone: the finished form of the hole. That is the data geologists work from in trying to explain a collapse that opened where it did, on a day when the nearest well readings were in a normal range.

Some of the owners contested the condemnation of their property. The scans Dr. Collins made of the Ocean Pines Drive sinkhole are held by USF's Digital Heritage and Humanities Collections.