Section R. 408.41471 - Ground support; inspections; repairs Rule 1471.
(1) A qualified employee shall inspect the roof, face, and walls of portals, work areas, and haulage ways, or travel-ways at the start of each shift and frequently thereafter as needed. If loose soil or rock or fractured material is encountered, then it shall be scaled or protected and supported. The employee conducting the inspections shall be protected from loose ground by location, ground support, or equivalent means. Suitable protection shall be provided for employees exposed to the hazard of loose ground while installing ground support systems. Support sets shall be installed so that the bottoms have sufficient anchorage to prevent ground pressures from dislodging the support base of the sets. Lateral bracing (collar bracing, tie rods, or spreaders) shall be provided between immediately adjacent sets to ensure added stability. Damaged or dislodged ground supports that create a hazardous condition shall be promptly repaired or replaced. When replacing supports, the new supports shall be installed before the damaged supports are removed. A shield or other type of support shall be used to maintain a safe travel way for employees working in dead-end areas ahead of any support replacement operation. (2) A scaling bar shall be in good condition. A blunted or severely worn bar shall not be used.(3) A torque meter and a torque wrench shall be available where rock bolts are used for ground support. Frequent tests shall be made to determine if the bolts are tight. The test frequency shall be determined by rock conditions and distance from vibration sources.(4) A damaged or dislodged tunnel support shall be repaired or replaced when structural integrity is impaired. A new support shall be installed if possible before removing damaged supports.(5) Tunnel supports shall be designed and installed to prevent pressure from pushing them inward into the excavation.(6) Roof supports shall be used where ground conditions are such that there could be a ground failure ahead of tunnel sets.(7) A tunnel that is to be occupied by employees shall be provided with a steel casing, concrete pipe, timber, or other material of required strength to support the surrounding earth.(8) If an employee is required to enter a tunnel or an auger boring and jacking operation less than 3 feet in diameter, then a lifeline for instant rescue shall be securely fastened to his or her ankles. Another employee shall be stationed at the tunnel entrance to operate the lifeline. In addition, ventilation shall be provided with an air line.Mich. Admin. Code R. 408.41471
1979 AC; 2003 AACS; 2019 MR 24, Eff. 1/3/2020