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Landfill Sinkhole Event

On December 14, 2010, a sinkhole formed at the Southeast County Landfill. This event was unprecedented at this facility, which is located in a remote area on County Road 672. Hillsborough County conducted extensive research before choosing this location. These studies showed geologic conditions in this area to be extremely stable and not prone to sinkholes.

When the sinkhole formed, the Hillsborough County Public Utilities Department acted swiftly to notify environmental agencies, create a highly-skilled project team, and implement a plan to monitor groundwater and surface water quality.

In coordination with engineering consultants and the Florida Department of Environmental Protection (FDEP), Hillsborough County developed and implemented a five-stage remediation plan to mitigate any potential impact to the environment, stabilize the sinkhole, repair the clay liner, and restore the damaged slope:

  • Stage 1, the initial injection of grout to stabilize the sinkhole area, was completed in April 2011.
  • Stage 2, the cut, fill, and relocation of waste from the sinkhole area, was completed in September 2011. This provided a safe working environment for tests.
  • Stage 3, the geophysical and geotechnical investigation, was completed in December 2011. A report detailing the Stage 3 results and the Stage 4 remediation plan were submitted to the FDEP in April 2012.
  • Stage 4, the geotechnical remediation and grouting, was completed in May 2013. The completion report for monitoring of the Stage 4 construction was submitted to the FDEP in September 2013.
  • Stage 5, the isolation of the impacted clay liner, began construction on Dec. 12, 2013. Stage 5 is expected to be completed by June 2014.

Every effort is being made to minimize any further impacts to the environment, ensure the safety of the workers and not impede the daily operations of the landfill. We are committed to moving forward with the repair efforts as quickly as possible, given the many complex factors involved.

Please keep visiting this page for updates on our progress.