The Bagnell Dam impounds the Osage River and upon completion in 1931 created Lake of the Ozarks, one the largest man-made lakes in the United States at the time. Currently operated by Ameren UE, the concrete gravity dam is a Federal Energy Regulatory Commission (FERC) licensed facility that is 2,543-ft in total length and comprised of a 520-ft gated spillway and 511-ft powerhouse section with 8 turbines. The dam received a structure upgrade in 2018, which included over 16,000-cy of mass concrete, 68-ea high capacity dam anchors, and 175-ea drains. The anchors ranged from 46 to 60-strands with lengths up 130-ft and the drains were 4-in diameter totaling nearly 12,000-lf.
The anchor installation across the dam’s spillway was most challenging and time sensitive portion of the project. All the work in the spillway had to be completed within a 6 month duration, starting in October and concluding in March, which is the timeframe where the spill risk was historically the lowest. In order to access the anchor locations, a 520-ft long by 30-ft wide steel platform had to be constructed to provide access to the anchor location. A 100-ton crane stationed on sectional barges was utilized to erect the platform and support the anchor installation. Next, drill crews worked an extended schedule to complete the installation of 33 anchors in just 4 months. Finally, the platform was removed just in time for the spring rains of the Midwest, allowing Ameren UE to operate the dam’s gates.
Read about it in a recent article published by ENR here