If you are a contractor in construction, safety is a top concern. When doing work on an excavation job, choosing the right shoring systems can be the difference between a job well done, or a disaster that ends in injuries or worse. An essential component of planning an excavation job is understanding the necessity of adhering to excavation shoring requirements.
The Occupational Safety and Health Administration (OSHA) defines an excavation as any man-made depression, cut, or cavity in the earth that requires the removal of soil or rock. A trench is defined as an underground excavation that is no wider than 15 meters wide, and is deeper than it is wide. Not all excavations are trenches, but all trenches are an excavation.
Because they are more narrow and usually deeper, a trench will have different safety requirements. Trenches are required to have protective shoring systems when they are as little as five feet deep, unless the trench was cut into stable rock. The goal is to keep the depression free of shifting soil once it has been removed. If the walls cave, there could be real problems.
OSHA has specific requirements to ensure the safety of the crew in an excavation. Easy methods of departure, such as ladders, steps, and ramps need to be within 25 feet of all workers for any trench deeper than four feet. As trenches get to deeper levels of 20 feet or more, a registered professional engineer is required to design shoring systems for the protection of the workers.
Yes, it must be a certified professional engineer to be within OSHA compliance. The concern is that a non-engineer might make a mistake and choose an inadequate method of shoring, or even choose scaffolding instead. Making that mistake has happened too often, and resulted in damages to equipment, injuries to workers, and some preventable deaths.
Scaffolding is not the same as shoring. To make that mistake on an excavation job could result in grave injuries, even fatalities. Scaffolding is only appropriate for jobs that require workers to make repairs to the outside of a building, or to the inner walls of the interior. Scaffolding is vertically oriented, lightweight, and yet strong enough to hold the crew members and all of their necessary tools. It cannot act as a support system though because it is not built for that, and an engineer is not required to sign off on plans for erecting a scaffold.
Shoring systems are a necessity for most excavations; remember, only a dig lesser than five feet does not require it. The types of shoring are as follows:
-Pressure or Chemical Grouting-Pressure Pile
The type best suited for your job’s excavation will be assigned by a designated certified professional engineer to ensure the safety of the crew. However, the most used shoring systems are often hydraulic and phenumatic. Likewise, the most common materials used for shoring are timber and aluminum hydraulic for its durability and light weight.
Scaffolding is not suitable for excavation trenches because it is not meant to act as a support system. It is necessary to point out what might happen if an engineer does not approve the shoring system, or a scaffold is used instead. One study found that about 50 fatalities and 1,500 injuries result each year to due insufficient trench support.
The OSHA website cites potential problems with soil mechanics, such as sliding or tension cracks. A tension crack will typically form horizontally between 0.5 to 0.75 times the depth of the trench, and will likely lead to toppling or sliding, both of which result in soil filling the depression. Clearly, the deeper the cut the more danger that is presented to crew members working along the bottom. Determining the soil type at the work site can help an engineer determine which type of shoring and building materials should be used.
Construction can be a hard job. It is absolutely vital that the dangers of working under such conditions be minimized. When undertaking an excavation job, it is essential that the proper shoring system be used. Do a soil test, consult a certified professional engineer, and keep your crew members safe.