How To Be Safe When Excavating For Large Building Foundation Trenches

Digging trenches is one of the oldest jobs with construction and excavation. The trenches were dug by hand during World War II. When building
deeper trenches, the sides had to be supported to prevent trench walls from breaking in.

Several innovations were made after the world war. With backhoes, digging trenches by hand seemed to disappear as a profession. In the 1950s, hydraulically operated backhoes were designed to help people dig very deep trenches quickly. With these innovations, walls no longer had to built as supports because no longer needed to be in trenches to dig and do work.

All types of trenches have what is called standup time. This is the time that passes from the moment you dig the ditch to the moment
the walls of the trench begin to collapse. It depends on many factors, including soil type, water content, weather conditions, and depth of the trench. 

The lift time can be  zero seconds or last up to several months because there are many difficult elements to predict. Before digging the trench someone has to take soil samples as an estimation method for standup time. Remember that soil condition can differ significantly a few meters from the soil sample.

As soon as the trench is dug, the workers go in the ditch, and do necessary work, such as laying pipes or installing telephone lines. If trench walls are not supported, there is a possibility they collapse and lock up workers in the ditch. Throughout history there have been 100 to 300 people die in the United States every year when trenches collapse.

The public is aware that the industry progress will sometimes have negative side effects. The use of trench boxes lessen the chance of negative outcomes. The trench box, also called a trench shield, can be placed in the ditch to avoid injury to workers. The trench box consists of two
large plates, mostly steel, that are parallel to the trench walls and horizontal cross braces that hold the two plates.

The bottom edge of the trench box sits at the bottom of the trench, with the top of the box that spans the top of the trench. Workers remain between the trench plates so that when the trench collapses, the dirt stops outside the trench box. As work progresses, the trench box is moved with a bulldozer or other machine.

When a project requires a large excavation, such as like digging for foundation construction of a great building the many details of the structure size and depth is to be specified in the plans. The big problem comes when trench boxes are not used in cities when water or sewer pipes are laid or repaired. The engineer does not specify trench box use in the plans and leaves the contractor to decide.

Whenever you are digging trenches, always uses common sense to guide you. Take your time. Trenches can be very deadly, especially when the trench boxes are not in use. A trench box should always be used to be safe when you need to be in the trenches. If you don't need to be in the trench, do the wise thing and the let the heavy machinery do the work it was built for.