It would be pretty tough to install any shoring system in an excavation 30 feet from a major body of water. However, that was the challenge facing Robstown, Texas, contractor Bridges Specialties when they were recently charged with installing a fiberglass lift station just 10 yards from the banks of Corpus Christi Bay.
The City of Corpus Christi-let project required the lift station to be set a modest 20 feet deep, however the water table started at about 7 feet deep. “We had to set up dewatering pumps for a whole week prior to starting the excavation, just to get the water level low enough to set our lift station,” says Brian Bridges, owner and operator of his namesake company. “And, the ground conditions changed during the dig. It was sand for 10 feet, then sandy clay after that,” Bridges explains.
“There was no way we could dig out a hole then set a (trench) box,” continues Bridges. “The only possible way to get down to grade was to install all the sheeting and then dig out within the system,” he says.
Featured Image: Bridges Specialties excavates 10 yards from Corpus Christi Bay in preparation to set a new lift station. The site required a full week of dewatering before excavating could be attempted.
Above: Bridges cast-in-place concrete around the bottom of the lift station to create a wider, square foundation. Eye bolts were cemented into the foundation, which the crane operator utilized to set the entire structure into the excavation.
For help with this challenge, Bridges contacted the Houston branch office of trench shielding and shoring equipment supplier Trench Plate Rental. Branch manager, Steve Hanley, had an immediate solution. “I proposed our Quicksheet™ Guideframe system,” says Hanley. “Bridges has used the guide frames before, and I knew Quicksheet would be perfect because it allows a contractor to push sheets down below the final grade of the excavation, and then dig out the pit,” Hanley says.
The Efficiency Production manufactured Quicksheet Guideframe has “mitered” corners with overlapping pockets that pin together like a door hinge, creating a 4-sided “picture frame” system that can be set up on the ground or in a shallow pilot hole. The 4-foot tall, 24-inch wide sheeting guide frame has a 7-inch slot where EP-10 sheeting can be stood up and overlapped, then pushed down with an excavator bucket. The guide frame for Bridges’ project was 16 x 16 feet square with 25 foot lengths of overlap sheeting.
Bridges used a 60,000 lb John Deere excavator for their work and a 120-ton crane leased through T & T Crane.
In order to make the 5-foot diameter, 22-foot tall fiberglass FRP Vessel stand up straight and plumb, Bridges cast-in-place 36,000 pounds of concrete around the bottom of the lift station to create a wider, square foundation. That addition also allowed eye bolts to be cemented into the foundation, which the crane operator utilized to set the entire structure into the excavation.
Trench Plate Rental also supplied exclusive pin-on pushing caps for the top of the sheeting which have recessed lifting lugs and provide more surface area for pushing the sheets into the ground. Bridges also utilized Ground QUICK-RELEASE™ Shackles—exclusively manufactured by Efficiency Production—that enables the shackle to be released from the ground, eliminating the potential dangers of climbing a ladder to undo traditional threaded shackles.
“This was the third time using the Quicksheet Guideframes, and they worked great,” says Bridges. “We are using them again on another project, as well.”
The Efficiency Production manufactured Quicksheet™ Guideframe shoring system has “mitered” corners with overlapping pockets that pin together like a door hinge, creating a 4-sided “picture frame” system that can be set up on the ground or in a shallow pilot hole.
CONTRACTOR AND SUPPLIER
Bridges Specialties offers a wide range of commercial, industrial, and residential services to the South Texas government facilities, municipalities, and local business. To contact Bridges Specialties, call 361.387.2743.
With branch offices in California, Texas, Florida, and Chicago; Trench Plate Rental is an official Efficiency Production, Inc. trench shielding and shoring equipment distributor. Efficiency Production, “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 standards. For more information, call Trench Plate Rental’s Houston branch office at 713.671.2551. ■
About The Author: James McRay is the director of marketing and media for Efficiency Production, Inc. He can be reached at 800.552.8800, or email: .
Modern Contractor Solutions – April 2016
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