Assessing Watauga Dam for Internal Erosion

Watauga Dam is a 332-foot tall, rockfill embankment with a compacted clay core. Completed by the Tennessee Valley Authority (TVA) in 1948, the dam is located in a steeply sided, mountain valley in eastern Tennessee. The dam’s vulnerabilities to internal erosion failure modes were recently evaluated as part of TVA’s ongoing dam safety assurance program. No seepage has been observed, but possible seepage exits are buried beneath the massive rockfill shell of the dam embankment. Potential internal soil erosion mechanisms were systematically cataloged and evaluated using historical design and construction records, numerical seepage models, and data from a network of installed piezometers. The compiled information will be used to support future, quantitative risk assessments of Watauga Dam, as TVA transitions to risk-informed management of dam safety. Lacking a well-defined, standardized analysis approach, this project provides a case study for the assessment of an embankment dam for safety issues related to seepage and internal soil erosion. 13 pp.