MT Projects Controls Corp - Project Management, Scheduling - Miami, FL - USA

Trench Shield Installation

trenchshieldI’ve seen on Linkedin another question that attracts me to another subject…trench shields.

And I was asking myself, do the contractors know which alternative to use? Which one is more productive? Sloping, shoring or trench boxes?

Because sloping requires no trench boxes or other shoring equipment, contractors often assume it is the least expensive method. However, the cost of removing soil and moving it away from the edges of a trench can be expensive and may exceed the cost of boxes or shoring.

After a trench is dug, workers go down into the trench, performing whatever work is necessary, such as laying pipe or telephone lines, welding pipe, or installing valves. If the walls of the trench are not supported, there is the possibility that the walls will collapse and trap the workers in the trench. Historically, there have been between 100 and 300 people killed in the United States every year due to trench collapses. So the requirements set forth in OSHA’s Excavation standard, 29 CFR 1926.650, .651, and .652 are:

1. All excavations or trenches 4 feet or greater in-depth shall be appropriately benched, shored, or sloped according to the procedures.

2. Excavations or trenches 20 feet deep or greater must have a protective system designed by a registered professional engineer.

3. Excavations under the base of footing of a foundation or wall need a support system designed by a registered professional engineer.

4. Sidewalks and pavement shall not be undermined unless a support system or another

Trench boxes are different from shoring because, instead of shoring up they are intended primarily to protect workers from cave-ins and similar incidents. The excavated area between the outside of the trench box and the face of the trench should be as small as possible. The space between the trench box and the excavation side must be backfilled to prevent lateral movement of the box. Trench boxes are generally used in open areas, but they also may be used in combination with sloping and benching. Any modifications to the shields must be approved by the manufacturer. Trench boxes are currently rated and stamped for different depths and in most states must be tagged/identified for depths when delivered to job site.

You can find below two interesting videos about trench shield installation presented by Efficiency Production.

Trench Shield Installation-Part 1

http://www.youtube.com/watch?v=b42mbNTjnJQ

Trench Shield Installation-Part 2

http://www.youtube.com/watch?v=ZhLhGYZOrsc&feature=relmfu

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