Excavation, Trenching and Shoring Safety
- Recognize the characteristics of a properly-established excavation site.
- Recognize cave-in protection requirements and identify proper procedures to keep employees safe in an excavation.
- Identify hazards in and around an excavation or trenching site, as well as necessary precautions and protective measures to keep employees safe from them.
Deaths caused by excavation cave-ins accounts for nearly 1% of all annual occupational deaths in the nation.
Before you begin any excavation, trenching, and shoring activities, you need to take specific steps to setup the site to avoid the accidental disruption of utilities, and assure the stability of adjacent structures—you need to engineer some controls and take precautionary measures. For examples, you need to ensure your safe access into and out of the excavation and avoid the hazards of contaminated atmospheres, falling materials, and the collapse of excavation walls, through the use of protective systems. There’s a lot that can go wrong with these scenarios, so awareness and preparedness are, as usual, critical priorities for protecting the workforce.
Prior to opening an excavation, you must take the proper steps to protect yourself, other employees, and any underground equipment. One of the first steps is for your employer to determine the location of utility installations, such as sewer, telephone, fuel, electric, and water lines, or any other underground installations. Most areas have a ‘call before you dig’ local resource for locating problem dig areas, so that’s a good number to have and share with your team; if excavation work is a daily part of your business, that number should be memorized.
To ensure your safety, the excavation must have a proper method of access and escape. Depending on the size of the excavation, this can include structural ramps, stairs, or ladders, used only by authorized employees; it is important to clearly mark areas to keep non-participants, like other contractors on a job site, out and away for excavation operations.
Here are some basic safety precautions for excavation work:
- Excavations that are less than four feet in depth do not require a stairway, anchored ladder, or ramp. Excavations that are four or more feet in depth require one of these structures, or other safe means of access and egress. This prevents employees from having to travel more than 25 feet to get out of the excavation from any point within the excavation.
- Also, walkways must be provided where employees or equipment are permitted to cross over excavations. Guardrails, complying with OSHA requirements, must be provided where walkways are 6 feet or more above lower levels. Stay aware of your surroundings. Never go beneath loads handled by lifting or digging equipment.
- Stay away from vehicles being loaded or unloaded, to avoid being struck by any spillage or falling materials. Operators can stay in vehicle cabs that are being loaded or unloaded when the vehicles are equipped to provide adequate protection for the operator.
- Warning devices are required if mobile equipment is operated next to or near the edge of an excavation and the operator does not have a clear view of the edge of the excavation. Warning systems include barricades and stop logs, and hand or mechanical signals. If possible, any grade should be sloped away from the excavation.
- Keep emergency rescue equipment on hand. A breathing apparatus should be on site, as well as a safety harness and lifeline, both of which are required in confined spaces, and a basket stretcher.
- To prevent surface water from entering the excavation and to provide adequate drainage of the area next to the excavation, use diversion ditches, dikes, or other suitable methods.
- In situations where the stability of nearby buildings, walls, or other structures is endangered by excavation operations, support systems are required. These systems may include shoring, bracing, and underpinning, to ensure stability and protect employees.
- In an excavation, you must be protected from cave-ins by a protective system. Protective systems include sloping and bench systems, and support systems, such as aluminum hydraulic shoring. These systems must have the capacity to resist any reasonably expected load that could be applied to the system.