Construction Excavation Safety

The trench will collapse.

If you have ever seen a person digging a hole, with a pile of earth looming above his head, waiting to collapse, then you have an idea of the dangers inherent in large scale excavation projects. Construction excavation, also called trenching, is an operation that digs large trenches, 30 to 40 feet deep, to install house foundations or pipelines. The dirt that surrounds the excavation site is not always firm, and can give way, burying those working in the trench. There are excavation guidelines to prevent accidents.

Types

Safety guidelines focus on: the process of digging the trench; maintaining the trench's structure when dug; trench collapse; non-collapse related hazards encountered in digging. All guidelines are set by the Occupational Safety and Health Administration (OHSA).

Safety While Digging

Safety features observed in the digging process are proper tools and equipment; human and machinery
interactions; proper method of digging in certain environment; human safety equipment. In a dig scenario
in which there are underground pipelines, heavy machinery cannot be used, unless the pipe is going to
be destroyed and removed, and is free of chemicals or potentially harmful liquids. When machinery is
being used, human co-workers need to stay within view, and not in the blind spots, of machine operators. General safety equipment includes a hard hat, protective glasses, work boots and reflective clothing.

Safety in the Completed Trench

Once a trench is dug, structural supports need to be positioned along its bottom and sides. Structural supports aid against trench collapse. A common structural support is the placement of metal sheets, 3 to 4 inches thick, along the sides of the trench. A trench can collapse, and procedures that cover trench exits and emergency response should be known and reviewed by each employee, and posted at the work site.

Chemical Hazard Safety

Old pipelines, which were not publicly recorded, may be damaged during the digging process. These pipes may contain liquids or even gases, which, if toxic, present an immediate danger. In the case of this type of risk, evacuation procedures are used, but steps are also taken to provide immediate aid to those working in the bottom of the trench. Gas or protective masks are located on site or nearby, as are first aid kits, which include skin and eye wash.

Considerations

Excavation safety guidelines would seem to be set only for operations that remove large amounts of dirt. For the guidelines related to trench collapse, this might be so. If a trench is being dug that is 5 feet or less in depth, collapse would only cause more work to be done. But a shallow trench does not exclude the use of machinery, and with that, blind spot safety should be observed.

References

• Trench Safety
• OSHA: Excavation safety
• Safety Library: Excavation safety
• Build Safe: Trenches