Ameren Missouri Bagnell Dam Stabilization Project
Lake of the Ozarks, Mo.
BEST PROJECT and Award of Merit, Safety
Owner: Ameren Missouri
Lead Design Firm: Rizzo Associates
General Contractor: MC Industrial, a McCarthy Holdings Co.
Civil Engineer: Brayman Construction Corp.
Hydro Demolition: Rampart Hydro Services LP
Concrete Placement: ACI Concrete Placement
The Bagnell Dam created the Lake of the Ozarks in Missouri after it was completed in 1931. The 2,453-ft-long, 148-ft-tall gravity dam holds back 600 billion gallons of water from the Osage River. In recent years, major dams such as the Oroville in California have failed, and smaller bridges and dams have been wiped away by rain and snow in increasingly wet Midwestern winters and springs. Dam owner Ameren Missouri decided to invest in reinforcement and fortification before nature threatened. In 2017, MC Industrial and Brayman Construction began work on the $52-million stabilization project that would eventually give Bagnell’s east section six new anchors, the west section 28 anchors and the spillway 33, each with 2 million lb of holdback capacity. A total of 17,000 cu yd of concrete on the downstream side of the dam had to be removed and replaced, all within an 18-month construction schedule.
“It was a risk decision for the company,” says Warren Witt, director of hydro operations for Ameren, which also owns the hydro power producing Osage Energy Center. “This dam, besides obviously holding back water for us to be a power plant, creates a billion-dollar tourism industry for the state of Missouri. If this dam were to degrade, not only would our power generation, but more importantly, the tourism business, real estate market, thousands of homes and everything else out here would be at risk.”
To deliver on Ameren’s timeline, MC Industrial used a concrete scrubbing robot; a color-coded project tracker tool that let all stakeholders know what state each anchor and section were in during replacement; and a movable scaffold that acted as its own concrete form. The new concrete added to the dam weighed 66 million lb.
“[Project Tracker] ensured that we had the best knowledge of our project at the time and applied it to the goals of our clients and our partners,” says Mike Hartwig, MC Industrial’s project manager. “Technology is obviously changing all the time, and we leverage our own in-house technology, plus some outside technologies, to make sure that our controls and our tracking are on the cutting edge.”
Data from the project also allowed safety patterns to be identified and assessed, helping the complex project—which had most of its work done on scaffolds and cranes on barges—to be completed with zero recordable safety incidents.
Hydro Demolition contractor Rampart Hydro Services provided the robot that removed 3 in. of worn concrete from the east, west and spillway sections. Thanks to close collaboration between the owner and contractors, the Bagnell Dam stabilization was completed ahead of schedule in August 2018 and well before the rainy 2019 winter that saw flooding in Iowa, Illinois, Nebraska and other parts of Missouri.