In response to a sinkhole discovered near the downstream toe of the earthen embankment at Boone Dam, and subsequent muddy, turbid discharge in the tailrace just downstream of the hydro-generation Unit 1 draft tube outlet, TVA implemented interim risk reduction measures to protect against progressive failure of the dam.
In the time following the observation, TVA completed multiple investigative tasks while evaluating different options for the mitigation of dam safety concerns, namely internal erosion into and through the karst bedrock. TVA decided to construct a composite seepage barrier extending through the embankment, foundation soils, epikarst, and into bedrock.
Geosyntec"s Scope of Services
Geosyntec is tasked with overall responsibility for the execution of the project Instrumentation Monitoring Plan (IMP) during completion of the deep grout curtain and concrete cutoff wall (COW). Geosyntec monitors the performance of the dam both through visual dam safety inspections and through real-time monitoring of dam safety instrumentation as well as the contractor"s instrumentation system during construction. Geosyntec provides "boots on the ground" with dam safety inspectors responsible for performing visual inspections 24-hours per day during construction and provides TVA with a first line of defense in order to identify symptoms of distress in response to remedial construction activities. Geosyntec provides real-time monitoring of dam safety instrumentation by actively reviewing and interpreting dam safety instrumentation data during construction and analyzing any observed trends in order to accurately diagnose the appropriate dam safety alert level during construction.
Geosyntec monitors, reviews, maintains, and evaluates over 200 vibrating wire piezometer transducers, three automated total stations surveying approximately 100 surface prisms, 14 slope inclinometers, including 10 automated Shape-Accel-Arrays (SAAs), and a full suite of crack gauges and tilt-meters located on the concrete dam. Geosyntec is responsible for the holistic evaluation of the data being collected in order to assess the performance of the dam through all phases of construction and changes in reservoir levels.
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- Location: Northeast Tennessee
- Client: Tennessee Valley Authority
- Project Practice Areas: Geotechnical
- Type of Facility: Development site
- Services Provided: Instrumentation Management System (IMS), Instrumentation Data Acquisition System (ADAS), Dam safety inspections, Geotechnical instrumentation data interpretation, Geotechnical grouting – Monitoring and Data Interpretation, Dam Safety Analyses
- Type of Work: Active landslide stabilization
- Governing Regulation: Federal and state