R 408.41482 Caisson excavation; employee protection.

Rule 1482. (1) An employee who enters a caisson shall be protected by a steel or concrete casing designed by a qualified employee and approved by a registered engineer. (2) A copy of the design specifications of the casing shall be maintained at the jobsite. (3) In the case of belled-bottom caissons, the steel or concrete casing shall be provided for the full depth of that part of each caisson hole that is above the bell. (4) An employer shall not permit an employee to work below the casing in running or unstable soil. (5) The steel or concrete caisson shall extend not less than 12 inches above the ground line. (6) Each employee who is required to enter a caisson excavation shall have a lanyard attached to a body harness and to the load line of a crane. The attachment to the load line shall utilize a screwpin shackle. (7) An employee whose lanyard is attached to the load line of a crane shall be permitted to be lowered to the bottom of the caisson in the muck bucket. (8) The maximum rate of travel when lowering an employee shall be 100 feet per minute. Free-spooling when lowering employees into a caisson is prohibited. (9) All employees shall be removed from the caisson when material is being hoisted from the caisson. (10) A secondary mechanical means that is capable of removing an employee from the caisson shall be readily available in case the crane performing the caisson work breaks down. (11) A top person shall be stationed at the caisson and shall constantly monitor any employees who are in the caisson. (12) A positive means of communication shall be maintained between employees working in the caisson and the top person. (13) The air quality of a caisson shall be tested and maintained in accordance with Occupational Health Standard Part 665 “Underground Construction, Caissons, Cofferdams, and Compressed Air,” as referenced in R 408.41410. (14) Where space permits, a caisson shall have a stairway for its entire height and shall have landing platforms not more than 20 feet apart. Where this is impracticable, a ladder shall be installed and landing platforms shall be located not more than 20 feet apart to break the climb.