When part of the roof over the Watts Reservoir near Pueblo, Colorado collapsed in the summer of 2021, it became clear that extracting and replacing it was going to be no easy feat, particularly since the roof covered a concrete cast-in-place tank that was 188 feet by 224 feet and covered over 42,000 square feet.
Responsible for holding up to 5 million gallons of potable drinking water, the Watts Reservoir was built by The Pueblo Board of Waterworks in 1931. In the mid-1970s, a roof was added to protect the reservoir’s use as a drinking source for area residents.
The roof was held up by over 100 precast twin tees, one of which collapsed due to corrosion, causing the entire structure to be compromised. Industrial Constructors/Managers, Inc. (ICM) was contracted to extract and replace the roof, which proved challenging since no one could get underneath it given the dangers involved.
“Only one precast tee failed, and we weren’t sure why,” said Devyn Novak, a project manager for ICM. “Given that, we had to treat the entire roof as being unsafe and capable of collapsing at any time.”
This led ICM to develop a one-of-a-kind rigging system to extract the damaged portion of the roof, along with a fall protection and arrest plan that provided 100 percent tie off for a span of over 200 feet in width, which was longer than ICM had ever accounted for.
“There was nothing off the shelf that we could easily buy given the size of the tank,” said Dave Montoya, safety director for ICM. “That made us develop a unique fall protection system that anchored independently from the reservoir, which was necessary in order to safely stabilize the men while they extracted and replaced the roof.”
Partnership and Teamwork Essential to Success
Luckily, ICM already had a freestanding fall protection system that had been designed in house and used for pre-engineered metal buildings, which the team used as a guidepost for developing the new system.
ICM turned to Printz Engineering Services to provide the calculations for the rigging system and for the custom fall protection plan given the unique dynamics of the project.
“Printz Engineering was a great partner in that they helped us ensure that our ideas would work on and off paper,” said Novak. “That was critical given the inherent risks of the project and the fact that we’d never had to extract a heavy material without an existing anchor in place to attach to.”
The resulting system consisted of two blocks of concrete that served as support anchors, which could be moved by a forklift as the project progressed. The blocks were tethered to a freestanding stanchion that was in the middle of the tank using a 200-foot cable that tied all three pieces together.
Two employees could be tethered to the system, fastened using self-retracting lanyards. ICM ended up creating two separate fall protection systems to enable four workers to be working at the same time, helping to speed up the timeline.
“The system was designed so there was no swing fall exposure, and the maximum height anyone could free fall was six feet, with two feet being more likely,” said Montoya. “It was also developed to meet all of the existing requirements for 100 percent fall protection, including being mobile and capable of withstanding 5,000 pounds per employee.”
With all systems in place, the roof membrane was removed, and the damaged twin tee was successfully rigged out. 116 total panels were removed in just two weeks despite a number of rain, sleet and snow delays. ICM completed the roof removal two weeks ahead of schedule, so the next phase of the project was paused until the new twin tee material arrived.
“The project wouldn’t have been successful if it weren’t for the partnership between ICM and Printz Engineering Services who worked together to develop and test new ideas,” said Novak. “Our collective commitment to ingenuity and creative problem solving ensured that our ideas would work in reality, enabling the project to be completed on time and on budget with no safety incidents.”
Tips for Creating an Off-the-Shelf Fall Protection System
While it’s not everyday that a custom fall protection system is needed, it’s important to be prepared to develop one if the project requires it. Below are a few tips to keep in mind when developing a solution that’s outside the box:
Brainstorm early with engineers
Most contractors are never short of ideas, but it’s important that ideas be grounded in reality, which requires testing them against calculations drafted by engineers. ICM started brainstorming early on with Printz Engineering Services, who provided the calculations to know immediately whether something would work or not. This saved valuable time upfront.
Keep existing fall protection requirements in mind
Just because you’re developing something new doesn’t mean that you can sidestep all of the existing requirements, which include specific weight limits and mobility parameters. These standards exist to protect employees from the dangers of a fall so it’s important to keep them front and center so that they have the protection they need while on the job.
Design with variable weather in mind
This project was done during the winter and spring months in Colorado, which meant that snow, sleet, rain and wind all happened within just a few month’s time. This is to be expected in Colorado, which is why the anchors were built to sustain extremely high winds and wet conditions. However, even if the project was done in the summer, all of these weather conditions would have been factored into the design given the unpredictable nature of weather.
Provide safety training for all workers
When fall protection is used on a job, all employees should have fall protection training, regardless of whether they’re going to be using it that day. In addition, each day should start with a daily briefing to discuss top-line safety issues that includes a job safety analysis to identify hazards for the work planned and a review of the controls needed to prevent unwanted incidents. Daily site and equipment inspections should also be performed for all equipment onsite and during all phases of work.