Interview: How TVA safely brought down a compromised smokestack

Photo: TVA

Speaking at the World Demolition Summit (WDS) in Nashville in November, Jason Curtstinger, Senior Manager of Demolition at the Tennessee Valley Authority (TVA), garnered much praise for his review of a recent implosion project at a fossil plant in the Tennessee River Valley.

During the decommissioning of several retired smokestacks, one modern scrubber stack, part of four structures imploded on the site, did not fall as planned.

Instead, it squatted rather than toppling, creating a compromised structure that required immediate re-evaluation.

In an hour-long session at WDS, Curtsinger captivated delegates, revealing how the company went about turning what was an unexpected event into a learning moment. And ultimately, a successful project.

“This stack was unique,” Curtsinger tells Demolition & Recycling International (D&RI). “Out of all the sites where we have performed implosions, we have not had any issues like this. We ended up with a compromised stack, but our priority was always safety.”

Cross-disciplinary coordination

Curtsinger speaking at WDS 2025.

The initial implosion took place in August 2024, with DH Griffin contracted as the prime contractor. DH Griffin then hired the engineering and demolition firms involved.

To ensure safety and precision, a third-party engineering firm was also brought in to review plans and calculations following the initial implosion event.

This, says Curtsinger, meant that cross-disciplinary coordination work between the respective teams was key, especially at this stage of evaluation.

“We held routine meetings, at least two to three times a week, and shared models and ideas. The two engineering firms utilized different finite element models, reviewed each other’s work, and ultimately aligned on the plan for felling the compromised stack.

“That collaboration continued even after the stack was down, as we evaluated what caused the squatting and what we could learn.”

Initial planning considered multiple approaches, including traditional blasting and redrilling. However, the remote-operated excavator with hoe ram attachment emerged as the safest option. This particular piece of equipment was owned by DH Griffin for use in high hazard situations to maximize worker safety.

“When we evaluated the amount of time people would be working under the stack with drilling and blasting versus the remote-operated excavator with hoe ram option, it was easy to see the remote operation was safer with zero people next to the stack versus a crew working for three or four days. From a safety perspective, the decision was clear.”

Adapting to unexpected conditions

Unexpected conditions during the implosion forced midcourse adjustments. The stack leaned unpredictably, requiring updated survey data on its off-center position and height.

Both engineering teams updated their models with this data to ensure the method for bringing the stack down was reliable.

“Because we were running two different models on separate platforms, we had to confirm they were working well together. Once we did, we felt confident the stack could be safely brought down,” says Curtsinger.

Again, communication remained critical throughout. TVA maintained an open flow of information from leadership down to contractors.

“We at TVA did not dictate the solution,” Curtsinger notes. “We relied on the demolition and engineering experts to assess the options. We always had incremental steps to move forward, even if the entire project plan had to change due to conditions encountered.

“That methodical approach, taking the time to step back and analyse before moving forward, kept the project controlled.”

Lessons learned for the demolition industry

Curtinger’s keynote at WDS was well received by delegates

According to Curtsinger, the lessons learned from the event are key to informing industry practice.

He explains that measures such as strengthening hinges, adding additional cuts, and verifying existing information, such as concrete strength, can significantly improve the implosion design.

Adjusting the bird-mouth height and refining blast patterns are also critical factors, while running detailed computer simulations should model the stack’s unique structural behaviour.

The lessons are also being put into practice, with another power industry peer successfully imploding a thin-walled, wide diameter stack using the lessons learned from this project.

In that respect, Curtsinger emphasizes the importance of sharing lessons to improve industry safety; “The demolition industry should share these experiences. If knowledge is not shared, there’s a gap that could lead to incidents where people are hurt or structures are damaged.

“By sharing our experience, two similar stacks have since been brought down safely using the lessons learned from our event. They went down perfectly because the knowledge was applied.”

A blueprint for safe demolition

The project ultimately stands as a case study in safety, innovation, and collaboration, he says. The remote-operated excavator solution not only mitigated risk but also demonstrated the value of cross-disciplinary teamwork, thorough analysis, and adaptive planning.

“The implosion didn’t go exactly as planned, but no one was hurt, and power wasn’t interrupted. It ultimately was a technical success and a learning opportunity,” Curtsinger concludes.

After careful evaluation and the implementation of the innovative remote-operated approach, the compromised smokestack was safely brought down in September 2024, marking the successful completion of that project milestone.

“Moving forward, any similar structures will be evaluated in detail, with lessons from this project applied to ensure safety and effectiveness every time.”