Excavation depth rules in Alberta: when protection is required

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# OCCUPATIONAL HEALTH AND SAFETY CODE (cont.) ## Safe entry and exit (cont.) Section 456 OCCUPATIONAL HEALTH AND SAFETY CODE Part 32 AR 191/2021 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 …

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# OCCUPATIONAL HEALTH AND SAFETY CODE (cont.) ## Methods of protection (cont.) Section 451 OCCUPATIONAL HEALTH AND SAFETY CODE Part 32 AR 191/2021 (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 …

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# OCCUPATIONAL HEALTH AND SAFETY CODE (cont.) ## Exposing buried facilities (cont.) Section 449 OCCUPATIONAL HEALTH AND SAFETY CODE Part 32 AR 191/2021 (b) if the buried facility is not an electrical cable or conduit, the employer ensures that (i) it is no longer in use, and (ii) the owner of the buried facility gives the employer written consent to excavate or remove the facility. (c) - (e) Repealed. - 448(3) An employer may reduce the width of a hand expose zone for a high pressure pipeline to within 1 metre on each side of the pipeline locate marks if (a) the high pressure pipeline is not governed by the Pipeline Act, and (b) the employer obtains written approval from the owner of the high pressure pipeline. - 448(4) If the ground that will be disturbed lies within a pipeline right of way, an employer must (a) contact the operator or licensee of the pipeline, and (b) get their consent to disturb the ground. - 448(5) An employer must not allow the use of mechanical excavation equipment within 600 millimetres of a buried pipeline unless the use of the equipment is under the direct supervision of a representative of the owner of the buried pipeline. - 448(5.1) If an employer, on behalf of an electric utility, undertakes emergency work that (a) involves ground disturbance to a depth of no more than 500 millimetres below the ground surface, (b) is on the horizontal alignment or right of way of an electric utility structure, and (c) is determined by the employer to be in a location where no buried facilities are present in the area affected by the work, - the employer is exempt from the requirements of subsections (1) to (5). - 448(6) An employer must ensure that any exposed buried facilities are protected and supported SO that workers are not injured. - 448(7) If a pipeline is exposed during a work operation, an employer must notify the pipeline operator or licensee before backfilling the excavation. ## Exemption 4…