While my knowledge base doesn't contain specific documentation on excavation and trenching operations, I can provide general safety guidance based on industry best practices to prevent cave-ins and ensure worker safety.

Before starting any shovelling or digging, it's crucial to contact utility companies to locate any underground cables, wires, and pipes. In many areas, it is illegal to dig without having these utilities located. This helps prevent damage to utilities and potential hazards to workers. [1]

Precautions against cave-ins may 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
• Benching or making steps in the sides of the excavation

[2] The protective measures depend on factors like:

• The size and depth of the excavation
• The kind of soil (e.g., clay can break off in large chunks without warning)
• If the soil has been recently excavated (e.g., soil that is "loose" may cave in more readily)
• The water content of the soil
• Weather conditions (e.g., rainy, freezing temperatures

[2] Always wear proper protective clothing suitable for the task and work environment, such as safety footwear, gloves, and long pants. [1]

One cubic foot of soil can weigh over 45 kg (100 pounds), so even a small amount of soil falling into an unprotected trench can lead to serious injuries or fatalities. Being buried up to the waist can be fatal due to the pressure exerted on the body. [1]

Always choose the proper tool for the task and ensure it is in good condition. Keep your feet shoulder-width apart to stay balanced and avoid twisting your body when moving soil. [1]