Prairie State Generating Company: Conveyor Installation

At Prairie State Generating Company in Marissa Township, Illinois, a pivoting stacker conveyor forms a critical link in the plant’s operation, moving it from the mine to power generation facility across the highway.

ACME’s relationship with Prairie State began with a fly ash load-out project, establishing trust that led to this much larger and more complex project. When their essential system sustained damage and could no longer be repaired, Prairie State faced a challenge that demanded precision engineering, flawless execution, and zero margin for error. The replacement had to happen during a precisely scheduled 10-day outage window—any delay could risk disrupting power to the 2.5 million families across 180 communities in nine Midwestern states who depend on Prairie State for baseload electricity.

The Challenge: Mission-Critical Infrastructure 

Understanding the stakes requires understanding Prairie State's operation. Coal is extracted from an underground mine and conveyed above ground, where it's moved through a series of conveyor systems. The pivoting stacker conveyor sits at the heart of this operation, distributing coal to two separate crushing and conveying systems that feed the power plant.

The stacker can pivot between the two underground conveyor systems, and if both go down for maintenance, it can rotate to pile coal on the ground until repairs are complete. The stacker is critical to keeping the mining operations running. 

The complexity extended beyond the installation itself. Prairie State had identified a solution: relocating a previously decommissioned conveyor system. This approach required comprehensive reconfiguration and installation of equipment originally designed for different applications in a different location.

The timeline presented additional constraints. Prairie State's planned outage was scheduled for June 14–22, a date established two years earlier. Every project element had to align with this deadline.

ACME's Integrated Approach: Comprehensive Project Integration

We approached this challenge with our distinctive integrated design-build capability, managing everything from initial design through final installation. This comprehensive approach eliminates the coordination challenges and communication gaps that typically arise when multiple separate contractors handle different project phases.

Planning began two and a half years before the installation.The original equipment manufacturer led the conveyor reconfiguration design to ensure the relocated system would function exactly as intended in its new environment.

Anvil Engineering, our structural engineering partners, took on the complex task of designing renovations to the existing foundation and support structures at the new location. They had to figure out how to adapt a foundation system originally built for a dual-rail conveyor to support a single-rail design, all while maintaining the structural integrity required for the massive pivoting loads.

TNT Fabrication, our fabrication partners, handled the custom structural steel work required for the installation. When existing components didn't fit the new application, TNT fabricated the specialized pieces needed to make everything work together seamlessly.

Engineering Innovation

The existing foundation system at the installation site had two rails supporting the conveyor. The relocated conveyor was designed for single-rail support. This meant completely rebuilding the foundation while keeping the existing system operational for as long as possible.

Our solution was ingenious in its simplicity: phase the work. They rebuilt a portion of the foundation first, then moved the new conveyor into position on the completed section. Only then did they demo the remaining original foundation and complete the rail installation, allowing the conveyor to pivot into its full operational range.

The most complex challenge was the installation itself. The conveyor was too heavy to lift and place as a single unit. The team had to develop an elaborate shoring system that would allow them to install the conveyor in sections while maintaining safety and structural integrity.

Where Planning Meets Reality

The old conveyor was systematically dismantled and removed, with sections carefully cut and disposed of. The installation phase demonstrated the value of ACME's integrated approach. With Anvil's engineering, TNT's fabrication work, and ACME's construction expertise coordinated under unified project management, coordination delays and accountability gaps were eliminated.

Our team worked methodically through the installation sequence: setting the shoring, positioning conveyor sections, connecting components, and verifying alignment. Each step had been rehearsed in the planning phase, and the crews knew exactly what needed to happen and when. 

The electrical installation, handled on a design-build basis, proceeded simultaneously with the mechanical work. Conduit routing and wiring installation were coordinated to avoid conflicts and minimize delays.

The Results: Success Where It Matters Most

On June 22, Prairie State's new conveyor system was operational. The plant's coal supply chain was restored on schedule, with no extension of the planned outage required. Most importantly, the installation was completed with zero safety incidents.

The system performed flawlessly from day one. The engineering calculations proved accurate, the fabrication work fit perfectly, and the installation met all operational requirements. Prairie State could immediately return to full production capacity with confidence in its upgraded coal handling system.

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