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Efficiency designed a two-bay 4-Sided Multi-Bay™ Configuration of Slide Rail to shore the working pit, with an inside dimension of 16 x31 feet, and 24 feet deep. But, the system had some unique modifications that enabled it to brace against the existing wall.
Efficiency’s Slide Rail System utilizes their exclusive Parallel Beam/Spreader Pipe Assembly as the cross brace. Innovative rollers on the Parallel Beams allow the entire cross brace unit to easily move up and down the inside face of the linear posts as the system is installed, and as the structure is formed in place.
Ferrantella innovatively attached a few feet of channel to the wall on each side of the linear posts to keep it from shifting.
The new CSO valve basin vault has an inside dimension of 10 x 20 feet wide, and 26 feet deep with a 2 foot poured footer. The (three) walls are also 2 foot thick.
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Where there’s a wall, there’s a way. Not a concept you’d normally associate with underground construction work. Yet for a portion of the Hammond (Indiana) Sanitary District’s recent Force Main Improvement Project, that concept was very applicable.
Subcontractor Ferrantella Construction Corp. was charged with building a new CSO valve basin vault directly against a large storm channel housing three new motor-operated valves; including tapping a 36 inch basin drain into the channel for diversion of storm sewer overflow. Because they needed to drill holes in that wall anyway, Ferrantella decided to cast-in-place three walls and use the storm channel’s west-facing wall as the fourth.
The storm channel is 18 feet wide, 30 feet deep, and runs for more than 100 feet. To make matters even more delicate, the old Headworks grit building is directly adjacent to the storm channel on the east side. The biggest challenge was excavating directly along the side of the channel to expose the west wall, while not damaging or undermining the 100 year-old-building on the opposite side of the channel.
The new CSO valve basin vault has an inside dimension of 10 x 20 feet wide, and 26 feet deep with a 2 foot poured footer. The (three) walls are also 2 foot thick. Therefore, Ferrantella needed to dig the working pit at least 28 feet deep, and wide and long enough to provide space to form up the structure. Did I mention that there was also a good possibility of encountering various unknown underground items?
Oh, and safely shoring the excavation was also a ‘minor’ problem for Ferrantella.
Excavating, shoring biggest challenge for contractor
“My initial thought was that this would be a sheet-piling job, but we were very concerned about all the underground obstructions and buried objects,” said Owner Mickey Ferrantella, “Can you imagine a sheet piling subcontractor hitting something? It would shut the project down for weeks.”
Ferrantella continued, “Back when we were bidding this, there were four reasons why we didn’t want to use sheeting: the Headworks building is a 100-year-old masonry building and the potential for damage or settlement by the vibrations of installing sheet piling was significant. Also, we were worried about the possibility of hitting an unknown underground item, working very far below the water table, and that the ground was very sandy all the way down to about the last 4 feet, which was then hard-packed clay.”
Ferrantella needed a low cost, safe, and effective alternative to sheet piling. “And, the shoring needed to be open on one side against the wall we were drilling,” Ferrantella added.
Slide Rail System from Efficiency Production provides shoring solutions
“My Superintendent, Joe Waterstraat, said to me, ‘Micky, I’ve been online and there is this shoring company, Efficiency Production, which has this very cool Slide Rail System that might work better than sheeting. I think we should get those guys down here,’” explained Ferrantella.
Ferrantella did contact Efficiency Production—a leading manufacturer of Slide Rail Systems and other trench safety equipment—and they sent their team of Slide Rail experts to the job site to determine if Slide Rail was a feasible shoring option.
It was, according to Greg Ross, Efficiency’s Manager of Slide Rail Systems: “Our system worked because our Slide Rail posts could be configured to brace directly against that existing wall. It’s actually not the first time we’ve designed a three-sided configuration of our Slide Rail System, needing to shore directly against an adjacent structure,” explained Ross.
Efficiency’s Universal Slide Rail is a component shoring system comprised of steel panels (similar to trench shield sidewalls) and vertical steel posts. The versatile system can be used in a variety of configurations, such as small four-sided pits; large unobstructed working pits as big as 50 x 50 feet with Efficiency’s ClearSpan™ System; or in a linear Multi-Bay™ configuration to install length of pipe over 40 feet.
Slide Rail is installed simultaneously as the trench or pit is excavated by sliding the panels into integrated rails on the posts–an outside slotted rail first, then an open-face rail on the inside–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” system. Efficiency Production is the only Slide Rail manufacturer to offer an open-face rail design on their Slide Rail posts.
Custom Designed Slide Rail gets the job done
To shore the working pit for Ferrantella’s vault to be built, Efficiency designed a two-bay 4-Sided Multi-Bay™ Configuration of Slide Rail with an inside dimension of 16 x31 feet, and 24 feet deep. But, the system had some unique modifications that enabled it to brace against the existing wall.
First, Ferrantella benched the entire excavation down 4-5 feet to get the system to a final elevation of 28 feet below existing grade. The two corner posts and linear post installed opposite the existing wall were 24 foot tall, but the corner posts installed abutted to the wall were 26 foot tall, and the linear post set against the wall was only 20 feet tall. Ferrantella innovatively attached a few feet of channel to the wall on each side of the linear post to keep it from shifting.
Efficiency’s Slide Rail System utilizes their exclusive Parallel Beam/Spreader Pipe Assembly as the cross brace. Innovative rollers on the Parallel Beams allow the entire cross brace unit to easily move up and down the inside face of the linear posts as the system is installed, and as the structure is formed in place.
From the inside of the completely formed CSO valve basin vault, Ferrantella core drilled three holes, 22 inches into the 24 inch wall of the storm channel. Then the three motor operated plug valves for the 36 inch basin drain pipes were set in place and lined up with the core drilled holes and secured before punching through the last two inches of the wall. The tap through the wall was secured with a set of new flanges. Then it was just a matter of core-drilling holes in the opposite, newly formed, wall to install the outflow drain pipes from the valves.
Ferrantella finished off by installing the precast top which contained a 30 inch manhole access with ladder; and a 66 x 66 inch ‘Bilco’ double leaf access door in case one of the plug valves needs to be replaced in the future.
Ferrantella Construction Corporation—www.ferrantella.com—provides a wide range of construction services for both the public and private non-residential markets. By self-performing nearly all work, they maintain the highest standards when it comes to quality, safety, customer service and ethics.
Efficiency Production, Inc., “America’s Trench Box Builder™,” provides the widest selection of standard and custom trench shielding and shoring systems. Efficiency’s versatile products are designed specifically for safe and cost effective installation of utility systems and infrastructure improvements. All products are P.E. certified to meet OSHA and MIOSHA standards.
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