Sinkhole Collapsesin Middle Creek

Collier Drive, Sevierville, TN

History

In 2010 a sinkhole developed adjacent to Middle Creek under the Collier Drive Bridge within the city of Sevierville Right-of-Way. It was determined that the development had caused a break in a city water line and was capturing the flow of the creek itself. The city immediately took steps to reroute the water line and stabilize the bridge; however, they did not deal with the sinkhole itself and the loss of the creek. After numerous discussions and meetings, it was decided that since this appeared to be a natural occurrence and was affecting waters of the state, the Department of Environment and Conservation should take action to try to correct the situation.

On July 18th, 2010, the state of TN Department of Environment and Conservation began work to stabilize the large sinkholes developing under the Collier Drive bridge and provide a pathway for surface water to flow again. The city of Sevierville agreed to provide logistic support to this undertaking.

On August 12th, 2011, a phone call was received from the city engineer reporting that an additional sinkhole had developed just upstream of the bridge outside of our previous work area. The sinkhole was extremely large and was capturing the entire flow of the stream once again. In addition, it was threatening an 8-inch sewer line from a nearby business.

We arrived on site Friday afternoon, August 12th and after consultation with the city, decided emergency actions needed to be taken to prevent further widening of the hole and loss of the sewer line and other damage. We began work that afternoon and put 39 truckloads of large diameter rock into the hole to stabilize it. These activities stabilized the hole for the weekend and final closure was performed the following week.

Are these sinkhole failures related to dewatering activities at the Vulcan Quarry?

A brief literature search indicates that groundwater withdrawal by quarries often results in increased sinkhole activity.

“Human-induced sinkholes in Karst commonly are caused by human activities that lower the water table below the rock/soil interface.”

“Of an estimated 4,000 sinkholes formed in Alabama between 1900 and 1976, only 50 were natural collapses.” (Newton, 1976)

(Potential Environmental Impacts of Quarrying Stone in Karst - A Literature Review. USGS 2001)

Human-induced subsidence most commonly occurs as a lowering of the ground surface due to the withdrawal of massive amounts of groundwater (Ruthven, et. al., 2002). The removal of large amounts of groundwater in Karst areas reduces the water pressure in the pore spaces of the bedrock, as well as the bedrock strength. This allows for the weakened areas to collapses.

(http://www.uwec.edu/jolhm/eh/below/Matt%20Below%20-%20GEOG%20361-sinkhole.htm)

(http://www.donan.com/sinkhole-collapse)

Typical Sequence for Sinkhole Formation

Google earth cross-section insert

Vulcan’s likely defense

Most of the groundwater is coming from the river.

Bridge/utility construction activities have caused/contributed to the sinkhole.

There may be other groundwater users in the area contributing to the lowered water table.

Geologic features may be affecting groundwater flow.

Recommendations to Determine Vulcan’s Impact

Dye-trace study

Potentiometric mapping

Further geologic mapping