An excavation is any man-made cut, cavity, hole, trench, or depression made in the earth’s surface by the removal of soil. Workers in excavations can be exposed to cave-ins, engulfment, hazardous atmospheres, and falls. Excavation safety training and procedures prevent serious injuries and accidents.
Before work on an excavation can begin, surface hazards such as unstable buildings, sidewalks, etc. that could endanger employees must be secured or removed. Hazards below the ground must also be identified and made safe before work can begin. Call 811 at least 2 days before the excavation. They will contact utilities so that representatives can determine if there are buried pipes or utilities in the planned work area. Excavations near sewers, landfills, chemical plants, and storage tanks for hazardous materials may have hazardous atmospheres. Excavations require inspection for hazardous atmospheres like low oxygen levels, high chemical concentrations, and/or flammable/explosive gases. Excavations deeper than 4 feet need to have atmospheric testing. If there are atmospheric hazards present or they could be present, ventilation, respiratory protection, and rescue equipment must be provided for worker safety.
Signs of soil distress near an excavation may indicate collapse or cave-in dangers. Fissures, cracks, or sagging/slumping materials from the open face of the excavation can indicate a hazard. Bulges at the excavation bottom, sinking at the edge, and small amounts of dirt and rock falling into the excavation are also signs of instability.
If the excavation is more than 5 feet deep, it needs a permit from Cal/OSHA and there needs to be a protective system (benching, shoring, sloping, etc.) in place to protect the workers inside. For excavations more than 4 feet deep, there needs to be a way to enter and exit the work area at least every 25 feet via a ladder, ramp, or other sturdy device.
Excavation inspections are required before work starts, during work shifts, and after rainstorms. A competent person that is familiar with excavation regulations and safety systems, how to type soils, and how to recognize excavation hazards must do these inspections. Inspectors should look for signs of cave-ins, failing protective systems, and potentially hazardous atmospheres. If hazards are found, workers should exit the excavation until the work area is made safe.
To protect workers from falling soil and rocks during excavation operations, perform maintenance scaling of the open excavation face to remove loose rocks from the excavation face. Use protective shields and retaining fences to hold back loose material. Keep spoils, supplies, equipment, vehicles, and workers at least two feet from the working edge.
Avoid working in excavations that hold or accumulate water. If work must be done in this situation, use protective shield systems, pumping devices, and harnesses with safety lines as added protection. The pumping system must be monitored by a competent person. Diversion systems and dikes can be used to re-direct flowing and encroaching water sources.