Seismic Investigation of Wateree Dam

The Wateree Hydroelectric facility, owned and operated by Duke Power Company, is located in Kershaw County, South Carolina on the Catawba River. The river is impounded by a concrete overflow spillway, powerhouse with integrated bulkhead and an earth embankment. The earthen embankment was constructed in the 1918-1919 time period using the puddle core technique wherein the central core was placed by dumping directly into the core pool. The project is licensed and regulated from a dam safety standpoint by the Federal Energy Regulatory Commission (FERC). The FERC has directed licensees to implement a program of seismic hazard evaluation for dams in the Eastern U.S. constructed using hydraulic fill techniques. Wateree Dam is located 120 km from Charleston SC, site of the 1886 Charleston earthquake. This paper describes the comprehensive site investigation program conducted at the Wateree Dam and details significant experiences from the program. The subsurface exploration program is the second phase in the evaluation of the Wateree Dam. Phase I was the determination of appropriate near field and far field design earthquakes and Phase III will be the analysis of the structure. A potential Phase IV would be the mediation of the structure, if required. The field investigation included extensive continuous SPT testing, geophysical testing, vane shear testing, and seismic cone penetrometer testing. Special considerations included delivered energy measurements for the automatic SPT hammers utilized correlation of the cone penetrometer with SPT data, and comparisons between shear wave velocities obtained from cross hole testing versus those measured with the seismic cone. The laboratory investigation included classification, strength and compressibility tests on SPT and thin walled tube samples of the embankment and its foundation. The results of the field/ laboratory investigation will be utilized to perform dynamic stability analyses of the embankment. This paper deals only with the results of the field investigation of the dam. It is the goal of this paper to discuss how various field investigative techniques complement each other and to summarize some of the results obtained for the published literature associated with dams constructed by the puddled core technique. 10 pp., 4 references.