By Mr. Hank Heusinkveld (USACE)November 13, 2018
A dedicated and experienced group of Wilmington District engineers and scientists earned the 2018 Dam Safety Team of the Year for its work on the Fort Jackson Dam Project Delivery Team (PDT).
Civil engineer Ed Dunlop headed the PDT that was formed in response to a request by officials from the U.S. Army installation Fort Jackson in South Carolina to assist with design and construction of repairs to Semmes Lake Dam, the Upper and Lower Legion Lake Dam, and Lower Twin Lake Dam after the damaging flood of 2015.
"The PDT started with an investigation of the dam failures, and through this early involvement by geotechnical engineers and geologists with the Fort Jackson Department of Public Works (DPW) we developed strong relationships which facilitated open dialogue and design input throughout the project life," Dunlop said. "The PDT solicited and involved more than 10 different stakeholders, including Fort Jackson DPW, other USACE organizations, the South Carolina Department of Health and Environmental Control (DHEC) staff, and private industry."
Dunlop said continuous, and face-to-face engagement resulted in a cohesive team effort. The team's robust engineering, professionalism and human quality earned complete trust and respect from the main stakeholders at Fort Jackson.
"Every component of the team, from the customer to the designers, was fundamental in executing a project that flawlessly followed a planned schedule, met all milestones and maintained the efforts within budget for the two-year duration of the design phase," he explained. "This efficiency was significantly promoted by the continuous engagement, support and mentoring from upper management within the Charleston, Jacksonville, and Wilmington Districts and the South Atlantic Division (SAD). The Savannah and Mobile Districts also provided key support roles in this effort.
The success of the team has shown the effectiveness with which USACE can mobilize resources across multiple districts to engage a challenging dam safety project and create strong relationships with the project sponsor and other interested parties."
Dunlop said that during their time at Fort Jackson the team developed a strong respect for the powerful weather events that caused so much damage. By standing in and observing the widespread destruction, they put extra effort into their work.
"Potential failure modes are identified during Periodic Assessments of a dam," said Dunlop. "When inspecting a dam emphasis is placed on locating signs of the potential failure modes. Inspectors can learn about what to look for by studying failures of other dams. One example of a failure mode is seepage through an earth embankment dam. Seepage can carry soil through the dam and over a period of time could form a path for water to flow. An inspector looks for wet areas on the downstream side of the dam, which may indicate seepage through the dam. Seepage through a dam can also be identified by depressions on the surface of the dam. Depressions on the surface can indicate that soil is being transported by seeping water from within the dam."
Dunlop said the Wilmington District team took direction from the Charleston District's Project Management section for the design and construction of the Semmes Lake Dam, while Engineering Technical Services performed surveys of the Semmes Dam site and prepared numerous cost estimates for alternatives that were studied early in the design.
In addition, Dunlop said Engineering Construction team members performed the Hydraulics and Hydrology analysis that determined the height of the dam and the dimensions of the labyrinth weir, and the Geotechnical section performed the geotechnical analysis that determined the internal zones of the dam, as well as seismic analysis that was used to set the elevations of the foundation of the new embankment.
Finally, the teammates of Engineering Design prepared the plans and specifications that the construction contractor will use to construct the dam and site features.
Dunlop said construction to build a new dam has been awarded, and that a pre-construction conference was held on Nov. 8, at Fort Jackson. The project is expected to take more than a year and a half to be completed.