Final pieces installed in Semmes Dam before water returns to basin

Published Dec. 22, 2020

Charleston District reassumes responsibility of military construction projects on Fort Jackson. The program covers new construction and renovation of headquarters offices, barracks, dining facilities and much more. Fort Jackson is the Army’s major hub for Basic Training, training roughly half of the all incoming Soldiers and more than 45,000 Soldiers every year.

After months of planning and coordination, a team of specialized construction personnel slid the final pieces of heavy concrete into place early November, finalizing the structural foundation of a new, modern dam at Semmes Lake on Fort Jackson.

Led by the U.S. Army Corps of Engineers, Charleston District, the Semmes Lake Dam project was authorized for reconstruction in 2018. The new structure will comply with all modern dam safety standards and, built using the latest innovations in engineering technology, is designed to withstand severe storms and flooding events.

An ongoing and collaborative effort with Fort Jackson, the three-year, $17 million project is on schedule to complete early next year.

Technical crews were prepositioned on-site early morning as a dozen 30-ton, 66-foot-long precast concrete arches arrived one-by-one from a manufacturing plant in Spartanburg. To prevent damage, the arch culverts — support beams for a future bridge — were then turned upward using a two-winch setup and then slowly lifted into the air. The crew used a special 400-ton capacity crane for the maneuver.

“This is a pretty unique process,” said Eric Jones, resident office project engineer, who has overseen military construction projects, including airfields and multifamily residential housing, at more than 15 installations. “I’ve been doing this a long time, and I’ve learned so much from this project.”

Once the project is complete and water has returned to the lake basin, the structure will support a small bridge and pedestrian path on the reconstructed Semmes Road.

Safety and environmental sustainability were the project’s most fundamental driving considerations.

“Designing and building a structure that is not only environmentally responsible but also integrates modern techniques and provides safe, resilient and long-term support to the greater Fort Jackson community has been at the forefront of every aspect of this military construction project,” said Charles Grainger, Semmes Lake Dam project manager.

The new dam utilizes a labyrinth weir to control water flow, diverting water into intended channels and preventing overtopping during storms or flooding events. Configured in a zig-zag or accordion-shape, the weir also requires minimal maintenance and can efficiently and autonomously adapt to fluctuations in water levels.

“One of the greatest benefits of the labyrinth weir is that, while proper maintenance and inspections are required, it has no operational requirement on a day-to-day basis or during storms,” Grainger said. “The structure is largely self-operational.”

The next step of the project involves rediverting Wild Cat Creek into its new permanent stream channel, through the new concrete spillway, and completing the earthen embankment, said Jones. The dam will stretch 970 feet long and rise 29 feet above the foundation.

Prior to the placement of the culverts, district leaders gave Brig. Gen. Milford Beagle, Jr. and Command Sgt. Maj. Philson Tavernier, commanding general and command sergeant major of the U.S. Army Training Center and Fort Jackson, a tour of the standing structure in the lake basin.

“Installation of the arch culverts is a major milestone for this project,” said Lt. Col. Rachel Honderd, district commander, Charleston District. “This is the final construction stage before water can safely return to the embankment and Semmes Lake can once again serve as a benefit for the Fort Jackson community. The continued success of this project is a testament to the professionalism of our team and our strong partnership with Fort Jackson.”

The Charleston District oversees several military construction projects on Fort Jackson, including the design, construction and renovation of schools, barracks, dining facilities and other structures. Fort Jackson is the largest Army training base for initial recruits, readying roughly 50 percent of all incoming Soldiers for future careers in the U.S. Army.