Overview of the Saluda Dam rehabilitation project: RCC and rockfill dams

Paul C. Rizzo Associates is the engineer of record for the seismic upgrade of the Saluda Dam located in Columbia, South Carolina. The selected remediation consists of constructing a combination Roller Compacted Concrete (RCC) and Rock Fill Berms along the downstream toe of the existing Dam. This Project is the largest active (year 2002) Dam construction project in the United States and the final Project will involve the placement of 1.3 million cubic yards of RCC and 3.5 million cubic yards of Rock Fill. The concept of the "fix" was developed by Paul C. Rizzo Associates and approved by the Federal Energy Regulatory Commission. The existing, semi-hydraulic fill, embankment Dam was constructed in 1930. Because of the method of construction used, the Dam is susceptible to liquefaction during the design seismic event. Due to the extent of liquefaction predicted, repair of the existing Dam would be difficult and costly. Several "repair" type options were considered, however the final remedial approach developed was to construct a back up Dam at the downstream toe of the existing Dam. For the majority of the 7,800-foot long embankment the Berm would be constructed of Rockfill. However, where space constraints exist, an RCC Berm is required. An extensive RCC testing program was developed to evaluate various RCC mix designs and to study the inclusion of landfilled, waste ash as a constituent of the RCC. The use of the on-site waste ash significantly reduced total project costs (through a reduced cement content) and provides for increase in available capacity in the existing ash landfill. Both the Rockfill and the aggregate for the RCC will be obtained from an on-site quarry. Upon completion of the Dam remediation project, the on-site quarry will be converted to an ash landfill which will provide 30 to 50 years worth of capacity for waste ash. The construction will be bid in two packages. The first package includes the installation of the dewatering system for construction. Construction of the dewatering system is expected to begin in February 2002. The contract for the Dam remediation will be awarded in the summer of 2002. Anticipated total project costs will be in excess of $200 million. 22 pp.