Trenching operations expose workers to excavation collapse, which kills several workers annually. A competent person must be present to inspect daily for hazards including ground movement, water accumulation, or cracked shoring. The competent person must understand soil classification: Type A stable clay, Type B mixed soil, and Type C unstable sand and gravel. Shoring systems must be installed correctly with appropriate size and spacing of supports. Sloping angles must be maintained according to soil type and excavation depth. For Type A soil, slopes must be 3.5 horizontal to 1 vertical. For Type B soil, slopes must be 1 to 1. For Type C soil, slopes must be 1.5 to 1. Shoring and bracing systems must be designed by a qualified engineer for excavations over 20 feet deep. Metal shields or trench boxes provide protection if positioned correctly. Ladders or ramps must provide safe access and egress at least every 25 feet. Water must be controlled with pumps or sumps to prevent instability and flooding. Daily inspections must be documented. Competent persons must have authority to halt work if conditions become unsafe. Heavy equipment must not be allowed near trench edges. Spoil piles must be kept at least 2 feet from trench edge. All personnel must be trained on trenching hazards.