Write a toolbox talk on trenching in tight areas

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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…

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- (a) cutting back the walls of the excavation to reduce the height of the remaining vertical walls, if any, to no more than 1.5 metres for 'hard and compact soil' and 'likely to crack or crumble soil', - (b) installing temporary protective structures, or - (c) using a combination of the methods in clauses (a) and (b). 450 (2) Subsection (1) does not apply if a trench is constructed in solid rock throughout the entire trench. ## Cutting back walls - 451 If the walls of an excavation are cut back, an employer must ensure that - (a) if the soil is classified as 'hard and compact soil', the walls are sloped to within 1.5 metres of the bottom of the excavation at an angle of not less than 30 degrees measured from the vertical, - (b) if the soil is classified as 'likely to crack or crumble soil', the walls are sloped to within 1.5 metres of the bottom of the excavation at an angle of not less than 45 degrees measured from the vertical, and - (c) if the soil is classified as 'soft, sandy or loose soil', the walls are sloped from the bottom of the excavation at an angle of not less than 45 degrees measured from the vertical. ## Loose materials 452 An employer must ensure that loose materials are scaled and trimmed from the sides of an excavation if workers may be on or near the sides. ## Spoil piles - 453 An employer must ensure that a spoil pile is piled so that - (a) the leading edge of the pile is at least 1 metre away from the edge of the excavation, - (b) the slope of a spoil pile adjacent to the excavation is at an angle of not more than 45 degrees from the horizontal, and - (c) loose materials are scaled and trimmed from the spoil pile. ## Power pole support 454 An employer must ensure that work that disturbs the ground in the vicinity of an overhead power line is performed in a manner that does not reduce the original support provided for power line poles. ## Safe entry and exit 455 (1) An employer must ensure that if a worker is required to enter a tren…

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- (b) where a trench cage is used, within the trench cage. - 168 An employer shall ensure that excavated material is - (a) kept at least 1 m away from the edge of an excavation or trench, unless an engineer certifies a shorter distance as adequate; and - (b) located a sufficient distance from the edge of the excavation or trench to ensure the excavated material does not re-enter the excavation or trench. Clause 168(b) amended: O.I.C. 2000-130, N.S. Reg. 52/2000. - 169 (1) An employer shall ensure that an excavation or trench in which a person works is kept reasonably free of water. - (2) Where a person may be exposed to a hazardous substance or to an oxygen rich atmosphere in an excavation or trench, an employer shall ensure that, before the person enters the excavation or trench, - (a) testing is performed to - (I) determine the concentration of any hazardous gas, vapour or dust, flammables, the concentration of oxygen and oxygen deficiency in the atmosphere in the immediate area of the excavation or trench where the work is to be performed, - (ii) ensure that the concentration of a chemical substance or a mixture of chemical substances in the excavation or trench does not exceed its occupational exposure limit under Part 2: Occupational Health of the Workplace Health and Safety Regulations made under the Act or 50% of its lower explosive limit, and - (iii) ensure that the level of oxygen in the atmosphere in the excavation or trench is not less than 19.5 % and not more than 22.5 %, unless the employer can demonstrate that an unsafe oxygen level is not possible in the circumstances; and Clause 169(2)(a) replaced: O.I.C. 2013-65, N.S. Reg. 53/2013. - (b) adequate precautions are taken to reduce the risk of injury to a person. Subsection 169(2) replaced: O.I.C. 2000-130, N.S. Reg. 52/2000. - (3 ) No person shall store hazardous substances in an excavation or trench. \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\…