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Description:
The Santee Cooper Project is a large hydroelectric and navigational development. It encompasses two major impoundments: Lake Marion on the Santee River and Lake Moultrie on the Cooper River. The two earthen dams impounding Lake Moultrie are the East and West Dams, as well as several earthen dikes. RIZZO performed a seismic evaluation for the East Dam and East Dam Extension at the FERC Licensed Santee Cooper Project. We analyzed the dams for a recurrence of the 1886 Charleston earthquake. Failure of the dam would result in a flood wave that would reach Charleston.
We performed a comprehensive subsurface investigation of the East Dam and East Dam Extension. This project involved drilling geotechnical borings, installing piezometers, performing static and dynamic slope stability analysis, preparing reports suitable for the FERC, and developing the final remedial design of the project. The project also included full-scale tests of the remediation approach and significant regulatory interaction. We determined that the foundation sands could liquefy in the event of the aforementioned earthquake.
RIZZO designed sand drains and stone columns to both reduce pore pressure build-up and strengthen loose soil zones. Additionally, a downstream berm was designed to increase the safety factor during the design earthquake. Various levels of remediation were applied over this long dam, reducing total construction costs. Our firm has also performed FERC Part 12 Safety Inspections, including Emergency Action Plan (EAP) updates, at the Santee Cooper Project.
RIZZO recently completed the design for the Upstream Slope Protection Plan for the Lake Moultrie and Lake Marion Dams. The remediation is intended to protect the embankment from failure caused by wave damage. RIZZO oversaw physical model testing of both existing conditions and proposed remediation alternatives to see how the structure would perform under real life conditions. Santee Cooper plans on implementing the remediation design throughout the next few years.
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