At what depth do I need shoring

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455 (2) An employer must ensure that if a worker is in a trench that is more than 1.5 metres deep, the trench is supported or sloped so that the worker can reach the safe point in order to enter and leave. ## Temporary protective structures - 456 (1) An employer must ensure that temporary protective structures in an excavation - (a) 3 metres deep or less are of sufficient strength to prevent the walls of the excavation from caving in or otherwise moving into the excavation, and - (b) more than 3 metres deep are designed, constructed and installed in accordance with the specifications of a professional engineer. - 456 (2) The specifications of a professional engineer for subsection (1)(b) must include - (a) the size and specifications of the structure, including the type and grade of materials used in its construction, and - (b) the loads for which the structure is designed. 456 (3) An employer must ensure that, before beginning an excavation, a foundation that may be affected by the excavation is supported by a temporary protective structure designed, constructed and installed in accordance with the specifications of a professional engineer. ## Alternatives to temporary protective structures 457 (1) Despite section 456, an employer may install the following as temporary protective structures in trenches: - (a) if the trenches vary in depth from 1.5 metres to 6 metres, shoring, stringers and bracing constructed of lumber that complies with Schedule 9, or a material that has equal or greater properties to those of the lumber; - (b) exterior grade plywood as a substitute for 38 millimetre shoring elements if - (i) the plywood meets the requirements of CSA Standard O121-08, Douglas Fir Plywood or CSA Standard O151-04, Canadian Softwood Plywood , - (ii) the plywood is at least 19 millimetres thick, - (iii) the trench is not more than 2.7 metres deep, - (iv) uprights are installed at intervals of not more than 600 millimetres centre-to-centre, - (v) cross braces do …

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## OCCUPATIONAL HEALTH AND SAFETY, 2020 - (3) An employer or contractor shall ensure that a temporary protective structure in an excavation more than 3 metres deep is designed and certified as safe by a professional engineer and installed, used, maintained and dismantled in accordance with that design. 31 Dec 2020 c S-15.1 Reg 10 s17-6. ## Protection against cave-in of trenches - 17-7 (1) If a worker is present in a trench that is more than 1.2 metres deep, an employer or contractor shall ensure that the worker is protected from cave-ins or sliding material by: - (a) cutting back the upper portion of the walls of the trench in accordance with subsection 17-4(2); - (b) installing a temporary protective structure; or - (c) a combination of cutting back the walls to the slope specified in subsection 17-4(2) and installing a temporary protective structure that extends at least 300 millimetres above the base of the cut-back. - (2) An employer or contractor shall ensure that a temporary protective structure required by clause (1) (b) or (c) is: - (a) designed and installed using shoring made of number 1 structural grade spruce lumber having the dimensions set out in Table 14 of the Appendix for the type of soil and the depth of the trench or made of material of equivalent or greater strength; or - (b) designed by a professional engineer and constructed, installed, used, maintained and dismantled in accordance with that design. - (3) An employer or contractor shall ensure that a temporary protective structure in a trench more than 6 metres deep in type 1, type 2 or type 3 soil or in a trench more than 4 metres deep in type 4 soil is designed and certified as safe by a professional engineer and installed, used, maintained and dismantled in accordance with that design. - (4) An employer or contractor shall ensure that: - (a) shoring is installed and removed in a manner that protects workers from cave-ins and structural collapses and from being struck …

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- 457 (4) Despite section 456, an employer may install additional protection certified by a professional engineer in trenches to compensate for passing vehicular traffic, working machinery or a heavy object placed within a distance equal to the depth of the trench, measured from the near edge of the bottom of the trench to the traffic, machinery or heavy object. - 457 (5) Despite section 456, an employer may install additional protection certified by a professional engineer in a trench to compensate for the stress created because the trench is adjacent to or abuts a building or other structure. ## Installation of shoring, stringers or bracing - 458 (1) An employer must ensure that a worker who installs shoring, stringers or bracing uses a ladder and works down from the top of the trench, installing each brace in descending order. - 458 (2) An employer must ensure that a worker who removes shoring, stringers or bracing uses a ladder and works upward from the bottom of the trench, removing each brace in ascending order. - 458 (3) A worker must install shoring, stringers or bracing in accordance with subsection (1) and remove them in accordance with subsection (2). - 458 (4) Despite subsections (2) and (3), if the quality of the ground in which a trench has been dug has deteriorated during operations to the extent that it is unsafe to use the method of removal required by subsection (2), an employer must ensure that the shoring, stringers or bracing are removed using a method that does not require the worker to be in the trench. ## Access for powered mobile equipment - 459 An employer must ensure that the open side of an excavation or a route used by powered mobile equipment to gain access to an excavation has a barrier high enough to stop the equipment from sliding or rolling into the excavation. ## Dumping block - 460 An employer must ensure that if powered mobile equipment may go over a bank or enter a dump opening while it is discharging its load, the equipme…