One cubic foot of soil can weigh over 45 kg (100 pounds) - a small amount of soil falling into an unprotected trench can injure or kill you. Workers have been killed after being buried up to their waist from the pressure exerted on their body.

Determine if you have to take precautions against the possibility of a cave-in. Precautions could include:

• sloping the bank to prevent a cave-in;
• shoring the banks with plywood, timber, or other materials to support the sides of a trench;
• installing shields or trench boxes; or
• benching or making steps in the sides of the excavation.

The protective measures that you have to take will depend on various factors like the size and depth of the excavation, and

• the kind of soil (for example, clay can break off in large chunks without warning);
• if the soil has been recently excavated (soil that is "loose" may cave in more readily);
• the water content of the soil; and
• weather conditions (e.g., rainy, freezing temperatures).

The precautions you take will be different if you will be working in the hole rather than standing on firm, stable ground at the top of the hole (e.g., post hole, hole for planting a shrub).

The OSH Answers document Shovelling contains ergonomic information (e.g., weight limit, handle length, work pace).