§ 153.144  TRENCH EXCAVATION PROTECTION.
   (A)   Open-cut trenches shall be protected in accordance with applicable rules, laws, and regulations of federal, state, and municipal ordinances, but shall not be less than the standards and regulations established by the Department of Labor, Occupational Safety and Health Administration, 29 C.F.R. part 1926, Occupational Safety and Health Standards: Excavations; Final Rule, hereinafter called OSHA.
   (B)   (1)   Protective systems may include two types:
         (a)   Structural support systems; and
         (b)   Sloping and benching excavation systems.
      (2)   No protective system shall be required for excavations occurring in other than stable rock up to five feet in depth unless the soil has been determined to be subject to potential cave-in based on tests and evaluations, or unless it has been found to experience cave-in during construction. If the excavation walls for trenches less than five feet in depth are subject to cave-in, a protective system shall be used in conformance with §§ 20-2.08 and 20-2.09 of the state’s Standard Specifications for Water and Sewer Main Construction.
   (C)   (1)   Any trench excavation which exceeds 20 feet in depth and occurs in other than stable rock shall make use of a protective system which is designed and approved by a state-licensed structural engineer for a structural support system or a state- licensed professional engineer for a sloped and benched excavation system.
      (2)   For trench excavations occurring in other than stable rock of a depth of 20 feet or less, the protection system provided shall conform to the requirements of §§ 20-2.08 and 20-2.09 of the state’s Standard Specifications for Water and Sewer Main Construction.
   (D)   Surface encumbrances that are located so as to create a hazard to workers in the trench excavation shall be removed or supported by the contractor.
   (E)   Ramps, runways, or ladders shall be provided for ingress and egress of workers from trenches which exceed four feet in depth in accordance with OSHA Standards.
   (F)   Water in trenches shall be controlled by the use of water removal equipment. If the trench excavation interrupts the natural flow of surface water, diversion ditches or dikes shall be used.
   (G)   When the stability of adjoining buildings, walls, sidewalks, pavements, bridges, or other structures is endangered by excavation operations, structural support systems such as shoring, bracing, or underpinning shall be used to ensure the stability of the structure. Excavation below the foundation of an adjacent structure which is not located in stable rock shall require either of the following:
      (1)   A state-licensed professional engineer has determined that the structure is sufficiently removed from the excavation so as to be unaffected; or
      (2)   A state-licensed structural engineer has designed and approved a structural support system to provide adequate protection to the structure.
(Ord. 97-7, passed 7-1-1997, § 5.16)