Kingston Ash Slide
Phase 1 Dredging
Updated March 20, 2009
The start of the dredging of ash from the Emory River Channel is an important milestone in the recovery of the Kingston site.
- TVA’s Phase I dredging plan has been approved by the Tennessee Department of Environment & Conservation and the U.S. Environmental Protection Agency.
- The plan was reviewed by TDEC, EPA Region IV, U.S. Fish & Wildlife, Tennessee Wildlife Resources Agency, and the U.S. Army Crops of Engineers and their comments incorporated.
- In preparation for the start of dredging, TVA has prepared the ash processing area to receive the ash, laid piping for conveying the dredged ash, and installed special noise reducing mufflers and other noise suppression equipment to reduce noise from the dredge equipment.
- A pilot study will be conducted during the first 60 days of Phase I dredging to determine the processing capacity for full-scale dredging, how the ash will move during dredging, and the effectiveness of dredging strategies.
- The primary equipment selected for the dredging process are hydraulic dredges for ash removal. Mechanical clamshells (or scoops) will be used to remove debris. Both types of equipment will be operated in a manner to minimize water turbidity. (Turbidity means the cloudiness of the water).
- Continuous water quality monitoring and routine water sampling and analyses will be conducted during dredging. TVA will review the water quality data and manage the work to minimize downstream impacts.
- Both dredged ash and daily plant production ash will be dewatered and processed on-site.
- Processing the ash in this manner will minimize the amount of ash entering the ash pond.
- The ash will be dewatered in the ash recovery area, and then moved to the ash operation/temporary storage area for further drying. (Read More)
- To minimize dust, TVA will continue to use water spray, a crusting agent, or other measures.
- Underground monitoring of the ash processing area for water pressure and movement will be incorporated.
- Potential offsite locations for ash disposal are being identified and investigated. Selection of permanent disposal sites will be discussed with and approved by TDEC.
- By its very nature, dredging has the potential to disturb ash and river water. When it approved TVA’s Phase I Plan for Dredging, the Tennessee Department of Environment and Conservation asked that TVA submit a sampling plan before the dredging work begins to ensure that dredging operations do not affect the health and safety of the public and workers at the site or the river and its natural resources. (View plan)
- The Phase I dredging is not intended to disturb the riverbed sediment. Only the ash that has flowed into the river channel from the Kingston site will be dredged during Phase I.
- Both before and during dredging, TVA and its contractors will perform extensive sampling and testing to ensure the work progresses in a way that minimizes adverse effects on the river and natural resources.
- TVA has performed additional sampling of the ash in the river to understand all of its chemical characteristics.
- The ash will also be tested to determine whether the metals in the ash are in a form that plants or animals may absorb (bioaccumulate).
- Standardized tests for toxicity and bioaccumulation will be used that are accepted by EPA and state agencies.
- The TVA sampling plan also details how TVA will use the water quality monitors to measure the turbidity, or cloudiness of the water during dredging.
- Five floating platforms on the river will continually measure temperature, dissolved oxygen, conductivity, pH and turbidity upstream and downstream of the dredging operations. This data will be collected every 15 minutes and sent to a computer at the Kingston Fossil Plant, where it will be processed automatically and monitored for significant changes.
- Boats will be used to find the plume of turbidity and take samples from the center of the plume. These samples will be tested for a variety of constituents, including alkalinity, total hardness, total suspended solids, total dissolved solids, mercury, total and dissolved metals.
- TVA will continue to sample and analyze water from five fixed locations on the Emory River, four locations on the Clinch, and one (or two) locations on the Tennessee River. Samples from these locations have been monitored three times a week by TVA since the week of December 22, 2008. TDEC will also continue its surface water monitoring independent of TVA.
- Based on the results of the monitoring, TVA will use several different methods to ensure turbidity levels remain within acceptable limits. These include reducing the pace of dredging, deploying turbidity curtains in the river, and moving the dredge to a different area.
- Water-based recreation on the Clinch and Tennessee Rivers should continue as usual this season, without impact from the ash spill.
- While the Emory is open, navigation is limited in the area near Kingston Fossil Plant; and that area continues to be a construction area for the foreseeable future. Recreational boaters should avoid this construction area.
- The Tennessee Department of Health fact sheet contains the following statement about recreation: "We are aware that many people are concerned about boating, swimming and fishing. People are advised to avoid contact with the ash, which is in the lower Emory River. At this time, recreation on Watts Bar outside the lower Emory River impact zone has not changed from the condition that existed before the ash spill. It is safe to swim, boat and eat most kinds of fish. Please see TDEC's Web site for more information about already existing fish consumption advisories. Monitoring will continue and decisions about appropriate activities will be continually assessed using the current sampling data."