The Gravity of Trench Safety

(Note: This is trench safety stand down week. If you need some material to present to a work crew, feel free to use the following, or any article I have posted. Keep in mind though, that this particular article only covers some of the hazards that to some extent involve gravitational forces. This is not a review of the entire OSHA Standard.)

Gravity is a force that we grow accustomed to, and that is certainly understandable. However, this force is responsible for many safety issues. Where and how does gravity show up in the OSHA Excavation Safety Standard? Here are 11 places specifically targeting hazards related to gravitational forces.

Surface encumbrances: Whenever we excavate near any object, be it a tree, a boulder, or a utility pole, the process of digging can make that object become unstable. If the object is not supported, gravity can cause the object to fall into the excavation.

Underground installations: We know the rules about calling 811 before we begin to excavate. However, once we have uncovered a utility, we must support it so it does not break or fall under its own weight.

Access and egress: Structural ramps that are to be used by construction equipment must be designed by a qualified person. This is to ensure that the ramp does not fail and the heavy equipment can safely move in and out of an excavation.

Ramps used by employees for access and egress must be designed in a way to prevent slip, trip, and fall hazards.

Exposure to falling loads: Employees are not to be underneath loads of any kind; and they must be protected from spillage hazards as well.

Warning system for mobile equipment: We must prevent equipment operating near the edge from falling off into the excavation.

Protection from hazards associated with water accumulation: Employees can get mired in soft soil that is saturated with water. There is also a slip, trip, and fall concern when working in wet conditions.

Stability of adjacent structures: Very similar concern to the first item in this list. Adjacent structures could become unstable during the excavation process.

Protection of employees from loose rock or soil: Employees are to be protected from soil or rock pieces that could fall from the face of the excavation. This is achieved by scaling the walls to remove the loose stuff, or, we can use sheeting with shoring systems to prevent the loose stuff from coming into the excavation.

Another concern is any excavated or other materials or equipment that could fall or roll into the excavation. The rule is to keep everything at least two feet back from the edge, or use an adequate retaining device.

Fall protection: Employees crossing over excavations that are six feet or deeper must be provided a walkway with handrails.

Requirement for protective systems: Employees shall be protected from cave-ins because gravity will cause vertical soil walls to fail. The federal rule is that this protection begins at five feet, but also is required at lesser depths where employees could be exposed to a cave-in. Gravitational forces do not end at 4’ – 11”. Again, the soil is going to cave-in at any depth, and we must provide an adequate protective system if the soil or rock from a cave-in will reach an employee.

Sloping and Benching Systems: Employees shall not be permitted to work on the faces of sloped or benched excavations at levels above other employees except when employees at the lower levels are adequately protected from the hazards of falling, rolling, or sliding material or equipment.

Gravitational forces account for the concern in each of these regulations. Each of these issues demand our concern and respect. For example, if an employee is positioned under a lifted load, it shows a lack of respect for the gravitational forces that are in play. There are so many things that can go wrong and cause a load to fall.

Since each of these hazards are serious, we should never take chances. Understand the gravity of the situation and recognized the hazards that are involved.

For more information about excavation safety please look up my reference guide “Trench and Excavation Safety by the Book”. It can be found at www.trenchandexcavationsafety.com