Underpinning safety planning is crucial in construction projects, especially when excavation work is involved. Here are some key safety requirements and considerations based on OSHA regulations:

1. Support Systems: Underpinning is a type of support system used to ensure the stability of structures adjacent to excavation sites. It is essential to provide support systems like underpinning, bracing, or shoring to protect employees and maintain the stability of structures that might be endangered by excavation operations [1].

2. Professional Approval: Excavation below the level of the base or footing of any foundation or retaining wall that could pose a hazard to employees is not permitted unless a support system like underpinning is provided, or a registered professional engineer has approved the excavation as safe [1].

3. Design and Maintenance: The design of protective systems, including underpinning, should be in written form and approved by a registered professional engineer. The materials and equipment used must be free from defects and maintained according to the manufacturer's recommendations to prevent hazards [2].

4. Installation and Removal: Support systems must be securely connected to prevent failure. They should be installed and removed in a manner that protects employees from cave-ins or structural collapses. Removal should be done carefully, starting from the bottom of the excavation, to monitor for any signs of failure [2].

5. Monitoring and Inspection: A competent person should monitor water removal equipment and operations to ensure proper functioning. Inspections are required when excavations are subject to runoff from heavy rains to ensure compliance with safety standards [1].

By adhering to these guidelines, construction projects can effectively manage the risks associated with underpinning and ensure the safety of workers and the stability of structures.