R 408.40943 Additional requirements for trench support systems.

Rule 943. (1) Members of support systems shall be securely connected together to prevent sliding, falling, kickouts, or other predictable failure. (2) The backfilling and the removal of a support system for a trench shall progress together from the bottom of the trench. In unstable or running soil, the jacks and braces shall be removed from above the trench after employees have cleared the trench. (3) The excavation of material to a level that is not more than 2 feet, .61 m, below the bottom of the members of a support system shall be permitted, but only if the system is designed to resist the forces calculated for the full depth of the trench and if there are no indications, while the trench is open, of a possible loss of soil from behind or below the bottom of the support system. (4) The installation of a support system shall be closely coordinated with the excavation of trenches. (5) Support systems shall be installed and removed in a manner that protects employees from cave-ins, structural collapses, or from being struck by members of the support system. (6) Individual members of support systems shall not be subjected to loads exceeding those which those members were designed to withstand. (7) Before temporary removal of individual members begins, additional precautions shall be taken to ensure the safety of employees, such as installing other structural members to carry the loads imposed on the support system.