Dallas 1 Construction & Development, based in Thonotosassa, Fla., recently completed an unexpected excavation project to facilitate the installation of dual 20 in. (51 cm) chilled water lines as part of the University of South Florida (USF) Chilled Water Loop Upgrade.
“Originally, we were not on site for the new chilled water line project, we were there to dig a jack and bore pit,” said Nick Maxwell, Dallas 1’s estimator. “But mechanical contractor Poole & Kent asked us to excavate, shore, and backfill for their installation of the new water lines because their original sub-contractor backed out,” Maxwell said.
Poole & Kent installed approximately 250 linear ft. (76 m) of dual, insulated-wrapped 20 in. steel pipe side-by-side, ranging in depth from 8 to 14 ft. (2.4 to 4.3 m). Each stick of pipe was 40 ft. (12 m) long. Most of the pipe joints were welded together in the pipeline excavation; however Poole & Kent had to weld two joints outside the trench once, creating one long 80 ft. (24 m) length of pipe that needed to be placed into the trench in one pick. This created a particular problem in placing such long pieces of pipe and still maintaining proper shoring of the trench.
To facilitate the protection of workers installing and welding the pipes in the trench excavation, Dallas 1 employed a series of trench shields to shore the pipeline. The trench shields (also known as trench boxes) were 8 ft. tall, 24 ft. (7.3 m) long XLD Series shields with 4 in. (10 cm) sidewalls manufactured by Efficiency Production Inc. and provided by Professional Shoring & Supply.
In order to manage installing the extremely long pipe into the trench boxes, Dallas 1 employed Hi-Clearance Arch spreaders on abutted ends of two shields, which essentially created an unobstructed clearance of 48 ft. (14.6 m), the length of two trench shields. This easily accommodated the 40 ft. lengths of pipe, and the one 80 ft. joint of pipe with some skilled maneuvering by Dallas 1’s excavator operator. The Hi-Clearance Arches pin-in-place over the trench shield sidewalls’ existing spreader collars.
A John Deere 330 excavator was used to excavate the trench, install the trench shields, and backfill over the new pipes.
Efficiency trench shields are designed and manufactured to stack on each other, and include stack packets to pin the stacked shields together. Dallas 1 stacked its trench shields when installing the pipe in depths exceeding 10 ft. (3 m).
OSHA allows trench excavations to exceed the height of trench shields by 2 ft. (.6 m)
All told, Dallas 1 rented approximately 18 trench shields from Professional Shoring & Supply’s Tampa office. They were supported by trench shoring specialist Paul Strazzula.
“The boxes worked great, no problems,” said Maxwell. “And we’ve know Paul for a long time, and he’s been real responsive to our needs.”
Dallas 1 Construction & Development’s core competencies cover three key areas: construction of infrastructure up to and including asphalt paving; installation of sewer, storm, and water lines; and site work and road preparation. It works primarily in west central Florida, including Hillsborough, Pasco, Polk and Pinellas counties. Clients include local municipalities, county and state agencies, and commercial developers.
With offices in Jacksonville, Orlando, and Tampa, Professional Shoring & Supply is an official Efficiency Production Inc. trench shielding and shoring equipment distributor. Efficiency Production, “America’s Trench Box Builder,” provides a wide selection of standard and custom trench shielding and shoring systems. All products are P.E. certified to meet OSHA standards.
For more information, call 888/777- 8307.
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