Excavation safety is critical to prevent accidents and ensure the well-being of workers. Here are some key safety measures and requirements based on the provided documents:

1. Protective Systems: Employees in excavations must be protected from cave-ins by an adequate protective system unless the excavation is in stable rock or less than 5 feet deep with no cave-in potential as determined by a competent person [1].

2. Water Accumulation: Workers should not work in excavations with accumulated water unless adequate precautions are taken, such as using special support systems or water removal methods [2].

3. Hazardous Atmospheres: Excavations should be tested for hazardous atmospheres, especially if they are deeper than 4 feet. Adequate precautions, such as ventilation or respiratory protection, should be implemented to prevent exposure to harmful atmospheres [3].

4. Stability of Adjacent Structures: Support systems like shoring or underpinning should be used to ensure the stability of adjacent structures that could be endangered by excavation operations [2].

5. Spoil Piles: Spoil piles should be kept at least 1 meter away from the edge of the excavation to prevent materials from falling back into the excavation [4].

6. Access and Egress: Safe means of access and egress, such as ladders or ramps, should be provided in trench excavations that are 4 feet or more in depth, with no more than 25 feet of lateral travel required for employees [3].

7. Inspections: Daily inspections by a competent person are required to identify potential hazards such as cave-ins or hazardous atmospheres. Inspections should also occur after rainstorms or other hazard-increasing events [1].

8. Emergency Rescue Equipment: Equipment such as breathing apparatus and safety harnesses should be readily available where hazardous atmospheric conditions exist or may develop [5].

By adhering to these guidelines, employers can significantly reduce the risk of accidents and ensure a safer working environment for employees involved in excavation activities.