Section R. 408.40942 - Supporting systems; angle of repose; tie backs; sheeting; additional bracingRule 942.
(1) The angle of repose and the design of the supporting system for a side of an excavation shall be based on the evaluation of all of the following factors: (a) Depth of cut and type of soil.(b) Possible variation in the water content of the material while the excavation is open.(c) Anticipated changes in the material due to exposure to air, sun, water, or freezing temperatures.(d) Load imposed by structures, equipment, overlying material, or stored material.(e) Vibration from traffic, equipment, or blasting.(2) A support system shall be designed by a qualified person. The design of the support system shall be maintained at the jobsite. Changes from the design of the support system shall be approved by a qualified person.(3) Tie rods and other forms of tie backs used to restrain the top of sheeting shall be anchored a minimum of 10 feet. The measurement to the anchor point shall start at the intersection of an angle of repose with the surface of the soil retained. The tie back and anchor shall be capable of restraining any pressure exerted on the system.(4) When sheeting or sheet piling is used, pressures due to existing ground water conditions shall be considered in the design. Sheet piling shall be driven to the predetermined depth set forth in the required design. Changes from the design shall be approved by the designer of the support system.(5) Materials used for a supporting system shall be in good serviceable condition. When timbers are used, they shall be sound and free of large or loose knots.(6) A supporting system shall include additional bracing approved by the designer of the support system when the sides of excavations are cut adjacent to a previous known excavation or a known fill, particularly when the separation between the previous excavation and the new excavation is less than the depth of the excavation.(7) Sheeting shall be braced or anchored at the bottom and along the vertical plane to prevent lateral movement.(8) Protective systems for use in excavations more than 20 feet in depth must be designed by a registered professional engineer.Mich. Admin. Code R. 408.40942
1979 AC; 2023 MR 24, Eff. 1/3/2024