PCL excavates to install a new cast-in-place vault in an extremely tight spot adjacent to several buildings. Simultaneously, PCL installs an Efficiency Production ClearSpan slide rail shoring system. The excavation site had such limited access, PCL’
Contractor PCL Construction Services in Orlando, Fla., currently is in the process of upgrading utilities and other infrastructure, as well as the streetscape at the Orlando Regional Medical Center. The multi-aspect project began in 2010 and is scheduled to be completed in November 2011.
As part of the infrastructure upgrade, PCL was charged with excavating and installing two cast-in-place mechanical vaults to provide access to control valves on the hospitals chilled water lines, steam lines and condensate lines. The vaults also house condensate tanks and pumps for the mechanical systems.
The first vault was 25 by 21 by 24 ft. (7.6 by 6.4 by 7.3 m) deep. The excavation to install the vault was in an extremely tight spot adjacent to several buildings and had limited access for equipment, plus the excavator could only dig from two sides. Providing the biggest challenge was safely shoring such a large excavation in such tight quarters.
“Sheet piling just wasn’t an option, because there was no access on two sides for the piling equipment, plus the hospital has very strict restrictions on vibrations near the buildings,” said Christopher Ritter, PCL’s project manager. “So we rented a slide rail system, which turned out to be faster than sheet piles and tie backs, and required less equipment.”
The slide rail system came from Professional Shoring & Supply in Orlando. Professional Shoring is an official distributor of Efficiency Production Inc.; a manufacturer of slide rail systems and other trench safety and shoring equipment. On-site assistance was provided by Professional Shoring Branch Manager Wayne Agamie.
Efficiency’s universal slide rail is a component shoring system comprised of steel panels (similar to trench shield sidewalls) and vertical steel posts. The system can be used in a variety of configurations. In addition to the obstruction-free ClearSpan configuration, Efficiency’s universal slide rail can be configured into small four-sided pits; or in a Multi-Bay configuration to install large tanks and structures or lengths of pipe more than 40 ft. (12 m).
“This was the first time our subcontractor had installed slide rail, but they picked up the knack for installing it very well and very quickly, and that was even with the ground being so wet that we needed to pump out the area,” Ritter said.
Overall, it took about five weeks to install the system, pour-the-structure and remove the system.
Because this was the first time PCL has used its slide rail system, Efficiency sent its director of slide rail systems Greg Ross.
“That’s very typical of how it goes with first time slide rail users,” said Ross. “The first day, they usually are intrigued on how and if it’s going to work; the second day, there is usually a bit of consternation as they have to overcome unexpected ground conditions and as they are trying to put the system in one piece at a time; but by the third day, they really get the hang of it, and they really start to figure out that this is a great system.”
They were very patient and a great bunch of guys to work with,” said Agamie. “They were very willing to learn and it was a pleasure doing business with them,” he said.
Slide rail is installed simultaneously as the trench or pit is excavated. The individual component pieces can be handled with a standard size excavator which means that excavation contractors can usually install the shoring system themselves. PCL used a Volvo 460 excavator to install the system. Inside the pit, PCL put in a Bobcat and mini-excavator to dig under the posts and panels and any spots the bigger machine could not reach.
Slide rail is installed by sliding the panels into integrated rails on the posts, and then pushing the panels and posts incrementally down to grade as the pit is dug; a process commonly referred to as a “dig and push” shoring system. Slide rail is considered “active shoring” which means that personnel and equipment can be safely in the hole throughout the entire installation and removal process.
PCL installed a 37 by 35 by 24 ft. (11 by 10 by 7.3 m) deep ClearSpan configured slide rail system. Efficiency’s ClearSpan design is unique in that it shores a large excavation without any need for cross-braces. The system stays entirely open by utilizing waler i-beams on the outside of the system at the top, and inside the system to prevent deflection. The walers integrate into the slide rail system with the use of custom brackets that slide along the posts. The inside waler brackets have rollers on the back allowing it to easily move up and down as the system is installed and removed.
The second vault PCL installed was a little smaller than the first. Ritter anticipated being able to use slide rail again, but, “We made sure that the soil conditions would work for it. It turned out to have better soil than the first location so using slide rail again was the right call.”
Plus, PCL was able to reuse the same slide rail system components as the first excavation.
The PCL family of companies is a group of independent construction companies which carry out diverse operations in the civil infrastructure, heavy industrial and buildings markets. PCL has an annual construction volume of more than $5 billion, making it the largest contracting organization in Canada and one of the largest in the United States.
With Florida offices in Orlando, Jacksonville and Tampa, and Houston, Texas; Professional Shoring and Supply is an official Efficiency Production Inc. trench shielding and shoring equipment distributor.
For more information, call 888/777-8307 or visit www.professionalshoring.com.