After setting a North American record for the most roller compacted concrete placed in a single day —18,590 cu. yds. — Columbia, SC’s Saluda Dam Remediation Project has been honored with the American Society of Civil Engineers’ (ASCE) 2006 Outstanding Civil Engineering Achievement (OCEA) award.
The OCEA award recognizes the project’s significant contribution to the civil engineering profession and its local community.
“South Carolina Electric & Gas Company [SCE&G] officials were faced with an extraordinary challenge when they realized the impact a repeat of the 1886 Charleston earthquake could have on Columbia’s three-quarters-of-a-century-old Saluda Dam,” said ASCE President Dennis R. Martenson. “Their proactive approach to protecting the surrounding communities, and the innovative methods they implemented to achieve that goal, make this project the embodiment of everything for which the OCEA award stands. We are proud to honor the Saluda Dam Remediation Project with this year’s award.”
When SCE&G officials learned that their 1.5-mi. long, 200-ft. high Saluda Hydroelectric Project dam embankment could liquefy during a repeat of the 1886 Charleston earthquake, they knew something had to be done.
However, whatever solution they developed had to keep a 78-sq.-mi. reservoir rimmed with homes and businesses approximately full and keep a hydroelectric plant and coal-fired steam plant operational, all the while ensuring the safety of the 120,000 residents living in the floodplain. The result was a 1.3-million-cu.-yd. RCC backup dam with zoned earthen abutments.
The project’s challenges prompted a method of placing filter zones and the design of a cooling method to enable concrete production during extremely high temperature. It also required usage of on-site waste ash and quarried aggregates, as well as the removal of roughly 10 million cu. yds. of material.
Due to the volume required, finding materials proved challenging, and ultimately, on-site borrow sources proved to be the best option. A rock quarry was designed to use available gneiss rock formations while avoiding schist formations and the on-site coal-fired steam plant served as a source of fly ash.
The benefit to the project was the use of 150 lbs. of fly ash per cubic yard of RCC, resulting in the use of approximately 200 million lbs. of on-site waste ash.
The project faced numerous challenges, including considerations for the local community. Lowering Lake Murray to rebuild the dam would have had unthinkable social and economic impacts, but the backup dam would have to be founded on dense soil or rock and some areas would require extensive excavation — as much as 60 ft. below existing grades.
However, the toe of a 200-ft.-high, active dam is a very dangerous place to dig. Extraordinary measures were required to maintain public and worker safety while retaining the 78 sq. mi. and 750 billion gal. of water that make up Lake Murray.
The only practical means to improve excavation slope stability was through intense dewatering efforts.
In total, 94 deep wells, 43 shallow wells and 824 eductor wells were installed to lower the ground water and to improve stability of the existing dam during construction.
Due to the array of environmental concerns the project created — protecting surrounding wetlands and a trout stream — full-time environmental engineers were included in the project staff to take a hands-on approach to staying within regulations.
Winner of the Engineers’ Society of Western Pennsylvania’s 2003 Heavy Construction Project of the Year award, the project also arranged work activities around residents’ schedules. For example, all blasting was done at lunch time when it was least disruptive to the neighbors. A sprinkler system and water truck also were installed to ensure dust arising from the three onsite batching plants and other activities could be immediately mitigated.
The project, owned by SCE&G, was led by Paul C. Rizzo Associates Inc., with Barnard Construction Company serving as contractor. Subcontractors included: Kleinfelder, Griffin Dewatering Southeast, H. B. Mellott Estate and Hayward-Baker/Nicholson JV.
Merit finalists for the 2006 OCEA award include two other South Carolina-based projects, the Liberty Bridge in Greenville, SC, and the Arthur Ravenel Jr. Bridge in Charleston, SC, in addition to the Neutrinos at the Main Injector (NuMI) Project in Batavia, IL, and Soudan, MN, and the Bridge Apollo in Bratislava, Slovakia.
Established in 1960 by ASCE, the OCEA program recognizes projects on the basis of their contributions to the well-being of people and communities, resourcefulness in planning and design challenges and innovations in materials and techniques.
Selected from a group of 20 entries, the 2006 winner and merit finalists are examples of how civil engineering can contribute to a community’s economic success, improve residents’ quality of life and facilitate scientific advancement. Previous winners include the relocation of the Cape Hatteras Lighthouse, the Trans-Alaska Pipeline and the World Trade Center Towers.