During the summer of 2021, one of the more than 100 concrete double-tee beams making up the roof system of a massive underground reservoir outside of Pueblo, Colorado, collapsed and failed. At 188 feet wide and 224 feet long, the cast-in-place storage tank—which serves the city of Pueblo’s water-distribution system—covers more than 42,000 square feet of land. It was originally cast in the 1930s, with the double-tee roof added in the 1970s.

Fixing the roof would involve much more than simply removing and replacing the beam that failed. “Since one tee failed, that’s really where the challenge came from,” says Devyn Novak, a project manager for Industrial Constructors/Managers Inc. (ICM), the Colorado-based industrial contractor that Pueblo Water retained for the job. “Because of that failed tee and not really understanding why it failed, the whole roof was considered to be compromised, and extra care really had to be taken in removing the existing roof system.”

But the job was always going to be difficult, regardless of its scope. “I don’t think there’s a lot of [water] tanks that are cast this away,” Novak says. “It’s one of those one-off, standalone tanks out there, so it created a whole lot of challenges because it’s one of its own.”

ICM’s primary concern was worker safety. In response, the company developed a unique fall-protection plan to safeguard employees while they removed and replaced the reservoir’s entire roof. True to ICM’s slogan, “We Love a Challenge”—this project truly was.

In-House Solution

As ICM worked out its approach to the difficult project, it became clear that traditional safety measures wouldn’t be sufficient to protect workers from a roughly 20-foot drop to the reservoir floor. Dave Montoya, ICM safety director, says he didn’t have any confidence that the compromised roof structure would be able to support employees once they got onto it. “Looking at the structure, just the size of it in itself was the challenge, because there’s nothing off the shelf that you could buy to meet this application,” Montoya says. “There’s nothing that we could anchor to. The fall-protection system that we used had to be something independent of the tank that we were working on.”

In addition to being freestanding, the solution needed to meet all the required standards for fall protection, including anchor-weight limits, and provide employees with adequate mobility to complete the project. ICM had already designed an in-house freestanding system to use for pre-engineered metal buildings and now used that model as a guidepost for a new system that used a moveable, two-piece concrete base and steel pipe. From there, the team would string cable across the reservoir, installing a stanchion in the center of the structure to keep the cable suspended high enough. Two self-retracting lanyards connected to the cable would allow employees to walk freely from one end of the reservoir to the other.

ICM presented this solution to Denver-area Printz Engineering Services, to confirm the company’s calculations. This was an important step, because the new system needed to be double the size of the existing model.

Above and Beyond

Once onsite, the team formed and poured the concrete to create the base, then used a forklift to move the blocks when they needed to be repositioned as the project progressed. ICM ended up building two of the rigs to make sure work was completed within the project’s four-month schedule. “[Pueblo Water] really gave us a tight deadline after the panel collapsed, in order to get this tank back in service for peak season,” Novak says. “That’s why we went with the two blocks, to keep as much manpower on the job as we could.”

The system provided fall protection for two employees at a time while they were perched on the damaged part of the roof over the water tank, preventing anyone from freefalling more than two feet, according to Montoya—much less than OSHA regulations of six feet. About two dozen crafts professionals worked together to repair and replace the collapsed roof, including carpenters, iron workers and cement masons.

Montoya emphasizes it was a group effort to create a safe fix. “It’s not only the responsibility of the safety manager or director, but you rely on the expertise and knowledge of the project team as well—the project manager, the superintendent,” Montoya says. “You have to rely on the people that perform the work. The reality is, they have the most experience in identifying and recognizing the work process and a lot of the challenges that go along with it. If you’re not utilizing your [teams’] work experience, you’re missing out.”