Bagnell Dam Turbine Refurbishment

When Ameren needed specialized millwright labor for a critical turbine refurbishment at Bagnell Dam, they relied on ACME Constructors for the work. That recommendation launched a complex project that would test our team's millwright expertise, safety protocols, and quality systems, all while working 150 feet below Lake of the Ozarks on equipment critical to regional power generation.

The Challenge: Restoring 80-Year-Old Infrastructure

Bagnell Dam houses eight hydroelectric turbines that generate power for the region. Two of those units, Unit 2 and Unit 4, were original equipment from the 1930s, and after nearly 100 years of continuous operation, corrosion buildup had caused efficiency to decline. 

Rather than replace them entirely, Ameren opted to machine existing components back to proper tolerances and restore them to like-new condition. The work would happen 150 feet below the water's surface in confined spaces. The main rotor alone weighed 312,000 pounds, and tolerances were tight. Everything needed removal, off-site refurbishment, and precision reinstallation. The scale of the equipment and the challenging environment demanded methodical execution and unwavering attention to safety.

The ACME Approach: Engineered Safety and Systematic Quality

The project kicked off in September 2024 with demolition work on Unit 2. The scope was clear: ACME would provide the millwright and ironworker labor needed to disassemble the turbines, prepare the housings, coordinate with specialists doing the refurbishment work, and then carefully reinstall everything once the components came back from being machined and restored.

ACME self-performed the millwright work along with the ironworker services needed for structural supports, platforms, and access systems. We subcontracted pipefitters to handle an aeration system being added to improve conditions for fish in the river below. And throughout it all, we worked alongside American Hydro's operators, electricians, and on-site machining specialists who would prepare the turbine housings for the refurbished components.

It was a complex choreography of different trades and specialties, all working in tight quarters far below the surface. The kind of environment where safety protocols and quality systems are essential.

Every Critical Pick Followed an Engineered Plan

When lifting a 312,000-pound rotor with overhead cranes, you don't improvise. Every critical lift was pre-engineered with rigging specifications detailed in advance.

Before each pick, the crew gathered for comprehensive safety meetings covering exactly what rigging would be used and how it would be installed. Roles were assigned. Questions were answered. Then the work area was taped off, and plant personnel were notified.

Rigging was inspected before every critical lift. All tags were verified, and each sling was carefully examined to ensure there was no damage to any part. Every shackle, every sling, every piece of load-bearing equipment got careful visual inspection. Tags were verified for certification and dates. Anything showing wear was immediately pulled from service.

We also brought in a third-party safety expert to monitor crew safety throughout the project—an additional layer of objective oversight ensuring safe work practices were consistently followed.

Quality Assurance Built on Multiple Layers of Verification

The verification system ensured that all assembly work was thoroughly inspected. After the crew completed a task, a second person would check it with fresh eyes. Every bolt had to be marked by two individuals, creating a clear record of inspection, before the work received final approval from both American Hydro's quality control team and the Ameren construction manager.

It's a meticulous process, but when you're working on equipment that was originally installed in the 1930s and needs to operate reliably for decades more, taking the time to get it right is the only acceptable approach. The multi-layered verification system meant that errors got caught early, quality was maintained throughout, and everyone could have confidence in the finished product.

The Execution: A Year of Methodical Progress

After demolition started on Unit 2 in September 2024, the crew worked through the fall to disassemble and remove components. By December and January, Unit 2 was shipped for refurbishment, and Unit 4 demolition was complete. While components were being machined off-site, ACME cleaned housings and prepared them for reinstallation.

In March 2025, the refurbished Unit 2 components arrived, and reinstallation began. Each unit took roughly three months of careful work where precision mattered more than speed. By September 9, 2025, both units were back in operation.

The Outcome: Client Satisfaction and Future Opportunities

Both turbines were restored to operation with improved efficiency. American Hydro expressed strong satisfaction with ACME’s performance on the project and indicated interest in future collaboration.

Ameren chose ACME for this project based on our proven millwright performance across multiple facilities. That decision, earned through consistent, quality work, is how major clients choose partners for their most critical infrastructure projects.

Throughout the year-long project, our rigorous safety protocols and multi-layered quality verification systems protected high-value equipment and ensured precision installation that Ameren can depend on for decades of reliable power generation. The project was completed on schedule despite the complexity of working in confined spaces 150 feet below the surface.

Whether you're facing turbine refurbishment, production line upgrades, or facility expansion, we bring the millwright expertise, safety protocols, and quality systems that major clients trust with their most critical work. Let's discuss your next project. Connect with an ACME expert today.