Construction projects sometimes require the digging of a trench for pouring a foundation, laying pipe, etc. Trenches are sometimes dug very deep, and there have been accidents in which the sides have collapsed, burying workers beneath piles of dirt and debris. Rope rescue classes can help you respond quickly and appropriately to a trenching accident. However, because a trenching accident can cause serious injuries and life-threatening asphyxiation, it is better to avoid one in the first place.
1. Create an Appropriate Slope for the Type of Soil
If the ground consists of rock or a fairly stable type of soil, the slope of the trench sides can be fairly steep. When digging directly into sandstone or granite, a 90-degree slope is acceptable for the trench walls, but no greater. However, if the soil is of a looser type, more prone to shifting, the slope should be much gentler, between 34 and 63 degrees, depending on the material.
2. Have Frequent Inspections
A competent person should inspect the trench thoroughly before anyone is allowed to go down into it after it is freshly dug. However, one inspection is not sufficient. Following any event that might increase the hazard, such as a heavy rainstorm, the competent person should conduct additional inspections.
3. Provide Adequate Exits
If workers are going down into the trench to work, they should have an easily accessible way to get back out again in case of an accident. Workers should never have to travel more than 25 feet to reach an exit out of the trench, such as a ramp, stairway, or ladder.
4. Calculate Trench Depth
A deep trench requires different safety measures than a shallow one. Therefore, it is necessary to know the depth of the trench. A trench greater than 20 feet deep should have a protective system designed by a professional engineer. Shallower trenches should be shored up appropriately to prevent soil movement and cave-ins.