If an excavation is deeper than 4 feet, ______________ must be used.

When an excavation exceeds a depth of 4 feet, it is crucial to implement safety measures to protect workers from potential cave-ins and provide a stable work environment. The correct answer entails the use of shoring, sloping, or stepping methods.

Shoring involves the use of support systems to prevent the walls of the excavation from collapsing. This is particularly important for deep excavations where lateral soil pressure can be significant. Sloping, on the other hand, involves cutting the walls of the excavation at an angle to reduce the risk of a cave-in, as this helps distribute the weight of the soil more evenly. Stepping involves creating steps in the excavation walls to enhance stability and provide easier access for workers.

These methods are recommended as they address the various risks associated with deeper excavations, ensuring both safety and compliance with occupational safety regulations. Failure to implement such protective measures can lead to serious accidents, making it imperative to adhere to these guidelines for excavations deeper than 4 feet.