Despite small size, sinkhole creates big concerns about groundwater in Leon County

September 3, 2013

sinkhole

Although local officials say they believe the sinkhole that recently opened in Leon County, Florida, does not pose a risk to residents of the Timberlake subdivision, they are concerned about how the geological activity could impact groundwater in the area, according to local media sources.

Tallahassee Democrat staff writer Karl Etters spoke to several municipal authorities and geological professionals, who indicated that they believe the formation of the sinkhole near Apalachee Parkway is “part of the natural shaping of Florida’s landscape.”

The sinkhole—currently about 15 feet wide—sits adjacent to a stormwater management pond, the digging of which may have played a role in creating the current situation.

Clint Krumhout, a geologist with the Florida Geological Survey, explained that when stormwater management areas are created, the overhead soil is removed, which often weakens the underlying limestone significantly, increasing the potential for underground caverns to collapse.

The heavy rains that have fallen on the region in recent weeks were also cited as a factor that likely contributed to the sinkhole’s formation. In a previous post, this blog explored some of the other environmental liabilities that could emerge in the Southeast as a result of storms during this year’s hurricane season, which is currently entering its peak phase.

Municipal officials cite groundwater protection as top concern

Theresa Heiker, stormwater management coordinator for the Leon County Department of Public Works, told reporters that “there are several ways to address this type of feature,” such as filling in the hole or putting a roof over the underground cavern to keep potential contaminants out of the Floridan Aquifer.

“It’s just a matter of making sure we’ve got the best recommendation of making sure the groundwater is protected,” Heiker said, adding that the county hopes to “determine a permanent solution” to the problem.

At this point, officials are saying that they believe the sinkhole has stabilized and, despite the fact that there a number of homes within 50 yards, there is no risk to any of the properties.

“We’re not concerned that the structures are at risk,” Heiker explained. “A lot of the time we get a small area that will open up and stabilize and then we go back to using the site.”

Krumhout also said he believes the risk of expansion is limited, noting that sinkholes “form everyday in Florida” and are often benign.

“It’s not uncommon that some farmer may get a sinkhole in his field, but if it doesn’t affect his farm, he may not report it,” Krumhout said.

He cited data from the U.S. Geological Survey, which shows that only two deaths have been attributed to sinkholes in the United States during the past 50 years. One of those fatalities was in the news recently, when a Florida man was swallowed in his sleep after a sinkhole opened up under his home.

Despite the low risk posed to nearby buildings, it is essential for authorities to be proactive in cases where groundwater may become contaminated. Working with independent consultants can help those responsible for managing a site collect enough data to get a full picture of the situation, while keeping costs to a minimum by limiting the number of mobilizations that are required.

For more information contact:

Amy Guilfoyle

PPM Consultants

407-240-1127