An excavation is basically an area where workers have removed earth. It can be a few feet to several meters. An excavation needs to be considered as a temporary structure. During an excavation, whether it is a trench or a well or any other type of digging, there is almost no way to assess how secure the surrounding walls are. Therefore it must be assumed that all walls have a strong potential to collapse. The question is not ‘will it collapse’ but rather ‘when will it collapse.’ This risk becomes greater when there is heavy machinery at the surface, removed soil is piled near the edge, after heavy rain fall, or if there is water inside the trench.
- As soil is collected will be placed at least 2 meters away from the edge.
- Whenever possible all digging of trenches/wells should be at 45 degrees, all the way around. Similar to an ice cream cone shape.
- If this is not possible supporting structures will be used for supporting the walls of wells or trenches. These structures are metal braces that have flat surfaces on each end and span from one wall to another wall directly opposite.
- These braces should be placed no more than every 2 meters.
- Heavy machinery should be as far away from the edge as feasibly possible when digging.
- Workers should not be in a trench that has not been made secure or when a machine is digging or when a machine is close to the edge of the wall.
More information on excavations.