After the three panels were set in a U-shape, footprinting the first ?bay,? the first Parallel Beam-Linear Post Assembly was set on the ends of the open panels. This cross-trench support, unique to the Efficiency system, is designed with special parallel beams that pin in place the standard trench shield spreader pipes. The parallel beams have rollers that allow them to be removed, creating an unobstructed, shored excavation.
To reach 16 ft. deep, the panels and posts were pushed incrementally until a depth of 8 ft. was accomplished. More 8-ft.-tall panels were then installed into the posts? inside open-face rails, and were pushed incrementally until the entire first bay was at grade. The second and third bays were installed in a similar manner. Once the entire system was at grade, level and backfilled with stone, T & B poured-in-place the tank?s concrete foundation.
After the ClearSpan waler beams were secured in the integrated brackets that slide down the outside face of the linear posts, the three parallel beam-spreader assemblies were removed for the tank set. This resulted in a 56-ft.-long unobstructed pit that was was able to accommodate the 47-ft.-long tank. The tank was set with a crane and backfilled with stone, while the slide rail components were pulled incrementally from the ground.
?[The slide rail system] really met my expectations,? says Burnside. ?As we were taking the system out of the ground, I thought to myself that I can use this [system] on another excavation project coming up in a few months. In fact, I wish I knew about this earlier, because it would have worked great on some other utility projects here at the hospital that we?d already completed.?
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