Identify causes of trench collapses
Identify protective systems to prevent collapses
Describe types of soil classification
Understand the role of the competent person on-site
Describe best practices in trench digging
One of the most dangerous jobs in construction is trenching and excavating. Excavation is any man-made cut, cavity, or trench made into the earth via soil removal. A trench is defined as a hole that is deeper than its width. Due to the uncertain nature of trenching, there's a high risk of injury or even death. Understanding the hazards associated with trenching and how to prevent them is vital in keeping excavation workers safe.
The most common hazard associated with excavation is a cave-in, or collapse. A cave-in is when soil or rock from the excavation falls into the trench in amounts large enough to trap, bury, or injure a worker. Several types of collapses can occur, but they all result in the person in the trench being trapped somehow. Fortunately, there are also ways this type of disaster can be prevented using protective systems known as shielding, shoring, sloping, and benching. Choosing the best protective system for the job is left up to a competent person trained in inspecting and mitigating hazards in trenches.
One of the most important steps that needs to be taken before excavation begins is soil classification. OSHA recognizes three types of soil: A, B, and C and stable rock. Stable rock is the most solid and Type C is the least, making it the most dangerous. The type of soil is important in choosing the correct protective system. Other factors to be considered when choosing a protective system are any cracks that form in the walls during excavation, water presence, and proximity to other buildings or roadways.
This course will help you learn how to safely begin an excavation by taking the proper precautions to avoid hazards like cave-ins. When it comes to trenching, you can never be too careful! Following proper digging practices, setting up the correct protective systems, and ensuring that all workers understand safety protocols can save lives.
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Stable rock, Type A, Type B, and Type C.
A competent person is a person who has been trained to recognize potential hazards and have them corrected at any point during the excavation. They are responsible for performing all inspections and ensuring the proper protective systems are in place.
Benching, sloping, shoring, and shielding.
Any trench over 5 feet deep must be protected from a cave-in, trenches deeper than 4 feet need to have a ladder system for entry and exit, ladders must extend 3 feet out of the trench for ease of access, spoil piles should be kept at least 2 feet from the trench edge, and one competent person needs to be on-site at all times.
The presence of moisture in the soil, weather conditions, nearby vibrations, the type of soil, and the location of the spoil pile are all conditions that may lead to a trench collapse during excavation.
Disclaimer: This training has been developed to teach about the best practices in trenching and excavation. This training includes information from Occupational Safety and Health Administration (OSHA) guidelines related to regulations 29 CFR 1926.650, 29 CFR 1926.651, and 29 CFR 1926.652, and related standards. Information provided hereafter is for educational purposes only.