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Sinkhole Event at the Southeast County Landfill

On December 14, 2010, a sinkhole formed at the Southeast County Landfill. This event is 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. Detailed plans, which are posted below, are guiding our efforts to assess and mitigate any potential impact to the environment, stabilize the sinkhole, repair the clay liner and restore the damaged slope.

A sinkhole in a landfill is unusual, and the situation will take some time to resolve. It is imperative that the remediation work proceed with great care and the right equipment and expertise. 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.

Hillsborough County Public Utilities Department

Reports & Plans	Maps

Stage 3 and 4 Cover Letter to the Florida Department of Environmental Protection, March 30, 2012
Stage 3 - Site Characterization Report
Stage 4- Geotechnical Remediation Plan
Stage 4 Geotechnical Remediation Construction Plans
Water Quality Monitoring Report No. 16 - for samples taken December 8-9, 2011. (Submitted to DEP January 17, 2011)
Water Quality Monitoring Report No. 19 - for samples taken March 7-9, 2012. (Submitted to DEP April 5, 2012)
Water Quality Monitoring Report No. 18 - for samples taken February 9-10, 2012. (Submitted to DEP March 20, 2012)
Water Quality Monitoring Report No. 17 - for samples taken January 5-6, 2012. (Submitted to DEP February 6, 2012)
Southeast County Landfill Sinkhole Event Update - February 3, 2012
Water Quality Monitoring Report No. 16 - for samples taken December 8-9, 2011. (Submitted to DEP January 17, 2012)
Water Quality Monitoring Report No. 15 - for samples taken October 3-4, 2011. (Submitted to DEP December 20, 2011)
Updated Sinkhole Remediation Schedule - December 7, 2011
Southeast County Landfill Sinkhole Event Update - December 2, 2011
Water Quality Monitoring Report No. 14 - for samples taken October 5-7, 2011. (Submitted to DEP November 10, 2011)
Water Quality Monitoring Report No. 13 - for samples taken September 8-9, 2011. (Submitted to DEP October 13, 2011)
Water Quality Monitoring Report No. 12 - for samples taken August 4-5, 2011. (Submitted to DEP September 2, 2011)
Stage 3 - Sinkhole Remediation Plan - Geophysical/Geotechnical Investigation Plan
Water Quality Monitoring Report No. 11 - for samples taken July 7-8, 2011. (Submitted to DEP August 10, 2011)
Stage 2 - Sinkhole Remediation Plan - Cut/Fill and Waste Relocation Plan
Water Quality Monitoring Report No. 10 - for samples taken June 8-9, 2011. (Submitted to DEP July 7, 2011)
Water Quality Monitoring Report No. 9 - for samples taken May 5-6, 2011. (Submitted to DEP June 14, 2011)
Water Quality Monitoring Report No. 8 - for samples taken March 31-April 1, and April 7-8, 2011. (Submitted to DEP May 11, 2011)
Water Quality Monitoring Report No. 7 - for samples taken March 10-11, March 17-18, and March 24-25, 2011. (Submitted to DEP April 29, 2011)
Water Quality Monitoring Report No. 6 - for samples taken Feb. 14-16, Feb. 24-25, and March 3-4, 2011. (Submitted to DEP April 7, 2011)
Water Quality Monitoring Report No. 5 - for samples taken Feb. 10, 2011, (Submitted to DEP March 16, 2011)
Fact Sheet - March 2011
Water Quality Monitoring Report No. 5 - for samples taken Feb. 10, 2011, (Submitted to DEP March 16, 2011)
Water Quality Monitoring Report No. 4 - for samples taken Feb. 3, 2011, (Submitted to DEP March 3, 2011)
Water Quality Monitoring Report No. 3 - for samples taken Jan. 13-14, Jan. 20-21, and Jan. 27-28, 2011 (Submitted to DEP Feb. 17, 2011)
Water Quality Monitoring Report No. 2 - for samples taken Jan. 4-7, 2011 (Submitted to DEP Jan. 27, 2011)
Water Quality Monitoring Report No. 1 - (submitted to DEP Jan. 13, 2011)	Southeast County Landfill General Site Geology - Phase I-VI - 3-dimensional view
Stage 1 - Sinkhole Remediation Plan - (Submitted to DEP Jan. 12, 2011)	Southeast County Landfill General Site Geology - Phases I-VI
Groundwater Contours - (Submitted to DEP Jan. 3)	Southeast County Landfill (County area)
Sinkhole Action Plan - (Submitted to DEP Dec. 22)	Southeast County Landfill (with roads)
Letter from DEP to Hillsborough County - (Dec. 15)	Southeaset County Landfill (5-mile radius)

Status Updates	Date/Time Posted
Status Update	4/09/2012
Status Update	1/06/2012
Status Update	11/04/2011
Southeast County Landfill Sinkhole Event Update	10/07/2011
Status Update	09/01/2011
Status Update	07/01/2011
Status Update	06/03/2011
Status Update	05/06/2011
Status Update	04/08/2011
Status Update	04/01/2011
Status Update	03/25/2011
Status Update	03/23/2011
Status Update	03/11/2011
Memo to Board of County Commissioners	03/09/2011
Status Update	03/04/2011
Status Update	02/25/2011
Status Update	02/18/2011
Status Update	02/11/2011
Status Update	02/04/2011
Letter to Neighbors	01/28/2011
Status Update	01/28/2011
Status Update	01/21/2011
Repairs for South County Landfill Sinkhole (video)	01/20/2011
Status Update	01/14/2011
Status Update	01/10/2011 at 4 p.m.
Status Update	01/07/2010 at 5 p.m.
Status Update	01/03/2010 at 4 p.m.
Status Update	12/27/2010 at 5 p.m.
Memo to Board of County Commissioners	12/22/2010 at 5 p.m.
Status Update	12/22/2010 at 5 p.m.
Status Update	12/21/2010 at 5 p.m.
Status Update	12/20/2010 at 5 p.m.
Status Update	12/18/2010 at 2 p.m.
Status Update	12/17/2010 at 5 p.m.
News Release	12/15/2010
Initial Report	12/15/2010 at 12 p.m.

Photo Library

August 31, 2011 � Filled with dirt, the sinkhole looks far different than when it appeared on December 14, 2010. The leveled area will provide a safe working environment for soil borings to determine if additional grout needs to be pumped below ground to fill any voids.

August 24, 2011 � The backfilling work continues.

August 23, 2011 � A tractor backhoe begins the backfilling work. Once filled, the area will better support the heavy equipment that will be needed for additional soil borings.

August 22, 2011 � Additional grout is pumped into the sinkhole before the backfilling operation.

Day 72 - 2/25/11

Soil borings will help determine where grout should be pumped - 2/1/11

A worker monitors the drilling rig that is taking soil samples - 2/1/11

Two new water quality monitoring wells were drilled close to the sinkhole - 1/10/11

Day 14 - 12/27/2010

Independent laboratory technicians take groundwater samples - 12/21/2010

Measuring width and depth - 12/16/2010

Day 2 - 12/15/2010

Day 1 - 12/14/2010

� Filled with dirt, the sinkhole looks far different than when it appeared on December 14, 2010. The leveled area will provide a safe working environment for soil borings to determine if additional grout needs to be pumped below ground to fill any voids. - 8/31/2011

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