These bridging elements should be built up on the ends with cribbing so that the material is stable and does not contact the immediate soil surface around the trench. The industrial side uses corrugated lightweight steel that is 12-inches wide and comes in lengths ranging from 4 to 20 feet. This is relatively unheard in technical-rescue circles where bridging is typically dimensional timber that is of adequate width to stand on and perform work (2 x 10 or 2 x 12). Industrial applications often eliminate ground pads in lieu of bridging because it requires less material and is more versatile.įraming out a trench is a relatively common practice on the industrial side. Traditional approaches to trench rescue use bridging to span the trench or slough zones. The disadvantage of this design is the loss of a center pivot point, which can make manipulating the panel during setting operations more difficult. This holds particularly true in trenches with standing water and propensities for bell pier collapses where the lower portion of the trench is a grave concern. The proposed essential removes the lower section of the strong back providing complete coverage of the trench wall. The advantage of this design is that the strong back acts as a pivot point when placing the panel and facilitates manipulation of the panel during setting operations. This is particularly evident when a slough zone is being back filled with soil and the soil continuously spills out at the bottom of the panel. The downside of this design is the bottom 12 to 24 inches of the trench wall is left untouched and ultimately not shored. Most panels are designed with strong backs (2 x 12 feet) that extend above and below the 4- x 8-foot panel by 12 to 24 inches and are fastened to the panel with recessed, engineered carriage bolts. Engineering and testing data shows that these options will fail at much lower forces than panels engineered with strong backs. Some applications used around the world apply spot-shoring techniques or panel designs without a strong back. Trench panels should include a center strong back. Essentials five through seven will be discussed next month. In this article we will discuss essentials one through four. These seven essentials require training and resources but yield tremendous returns. Use techniques and tools that completely shore the trench from the topside.Pneumatics and hydraulics provide a wide array of solutions that will fit a variety of budgets and are remarkably faster and more effective. Stop using timber and mechanical shoring.Acquire low-pressure trench bags for slough operations and trench wall deviations.Use bridging material as slides when placing trench panels.Increase the cribbing cache to support the bridging with remote contact points.Acquire a significant cache of bridging, preferably corrugated aluminum or steel, to frame out the trench.Consider removing the bottom of the pop sickle stick or strong back so that it is flush with the bottom edge of the trench panel.There are seven essentials that emerge through blending these industrial concepts with technical rescue concepts that will radically impact the speed, safety and efficiency of a trench rescue operations. We were indoctrinated into the "technical rescue" way of performing trench rescue until we were exposed to some industrial theories and techniques that were shared with us by Dennis Hobart of Baker Corp. With this being the driving mechanism, I am a firm believer that the approach and layout for trench rescue makes all the difference in the world. Knowing the hazards of the confined-space environment will help make an incident action plan
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