Excavation & Trenching – Know The Laws of Your Province

Excavation and trenching regulations are essential for ensuring the safety of workers involved in digging, tunneling, and earth-removal activities. These regulations require employers to assess soil conditions, locate and mark underground utilities, and implement protective systems such as sloping, shoring, or trench boxes. Safety measures include keeping excavated materials and equipment away from trench edges, controlling water accumulation, and ensuring safe access and egress. Workers must be trained to recognize excavation hazards and follow safe work procedures. While core safety practices apply nationwide, specific regulations vary across Canadian provinces and territories to reflect different site conditions and risks. Adhering to these regulations helps prevent cave-ins, utility strikes, and other incidents, fostering a safer working environment.

FEDERAL

In Canada, employers must follow excavation safety rules under the Canada Occupational Health and Safety Regulations, Part III, Section 3.12. They are responsible for marking underground utilities, installing barricades around hazardous trenches, ensuring proper shoring for excavations deeper than 1.4 m, and keeping materials at least 1 m from edges. A qualified person must oversee shoring installation.

Part III – Temporary Structures and Excavations

Excavation

(1) Before the commencement of work on a tunnel, excavation or trench, the employer shall mark the location of all underground pipes, cables and conduits in the area where the work is to be done.

(2) Where an excavation or trench constitutes a hazard to employees, a highly visible barricade shall be installed around it.

(3) In a tunnel or in an excavation or trench that is more than 1.4 m deep and whose sides are sloped at an angle of 45° or more to the horizontal:

(a) the walls of the tunnel, excavation or trench, and

(b) the roof of the tunnel shall be supported by shoring and bracing that is installed as the tunnel, excavation, or trench is being excavated.

(4) Subsection (3) does not apply in respect of a trench where the employer provides a system of shoring composed of steel plates and bracing, welded or bolted together, that can support the walls of the trench from the ground level to the trench bottom and can be moved along as work progresses.

(5) The installation and removal of the shoring and bracing referred to in subsection (3) shall be performed or supervised by a qualified person.

(6) Tools, machinery, timber, excavated materials or other objects shall not be placed within 1 m from the edge of an excavation or trench. Section 3.12 (1) to (6).

Further details on the Canada Occupational Health and Safety Regulations can be found at Justice.Gc.Ca.

ALBERTA

In Alberta, employers are required to ensure excavation and tunneling safety under the Occupational Health and Safety Code, Part 32, Sections 441 to 464. Employers must identify soil types, stabilize excavations with shoring or sloping, and clearly mark excavation zones. They are responsible for locating and exposing buried utilities before work begins, protecting workers with proper access, barriers, and safe entry points, and ensuring the use of engineered protective structures in deeper excavations, shafts, and tunnels. These measures are essential for preventing cave-ins, equipment accidents, and underground hazards.

Part 32 – Excavating and Tunnelling

Disturbing the Ground

For the purpose of this Part, ground is disturbed if a work operation or activity on or under the existing surface results in a disturbance or displacement of the soil, but not if the disturbance or displacement is a result only of:

(a) routine, minor road maintenance,

(b) agricultural cultivation to a depth of less than 450 millimetres below the ground surface over a pipeline, or

(c) hand‑digging to a depth of no more than 300 millimetres below the ground surface, so long as it does not permanently remove cover over a buried facility. Section 441.

Classification of Soil Type

(1) For the purpose of this Part, soil is classified as “hard and compact” if it closely exhibits most of the following characteristics:

(a) it is hard in consistency and can be penetrated only with difficulty by a small, sharp object;

(b) it is very dense;

(d) it has no signs of water seepage;

(e) it is extremely difficult to excavate with hand tools;

(f) if has not been excavated before.

(2) For the purpose of this Part, soil is classified as “likely to crack or crumble” if:

(a) it has been excavated before but does not exhibit any of the characteristics of “soft, sandy or loose” soil, or

(b) it closely exhibits most of the following characteristics:

(i) it is stiff in consistency and compacted;

(ii) it can be penetrated with moderate difficulty with a small, sharp object;

(iii) it is moderately difficult to excavate with hand tools;

(iv) it has a low to medium natural moisture content and a damp appearance after it is excavated;

(v) it exhibits signs of surface cracking;

(vi) it exhibits signs of localized water seepage.

(3) For the purposes of this Part, soil is classified as “soft, sandy or loose” if it closely exhibits most of the following characteristics:

(a) it is firm to very soft in consistency, loose to very loose;

(b) it is easy to excavate with hand tools;

(d) it runs easily into a well‑defined conical pile when dry;

(e) it appears to be wet;

(f) it is granular below the water table, unless water has been removed from it;

(g) it exerts substantial hydraulic pressure when a support system is used.

(4) If an excavation contains soil of more than one soil type, for the purposes of this Part an employer must operate as if all of it is the soil type with the least stability. Section 442 (1) to (4).

Soil Stabilization

(1) Subject to subsection (2), an employer must stabilize the soil in:

(a) an excavation by shoring or cutting back, or

(b) a tunnel, underground shaft or pit by shoring.

(2) An employer may stabilize the soil in an excavation, tunnel, underground shaft or pit using an artificial soil stabilization technique, including freezing soil by artificial means or grouting if the process used is:

(a) designed by a professional engineer to control soil conditions, and

(b) performed in accordance with the professional engineer’s specifications.

(3) A person must not use natural freezing of the soil as an alternative or partial alternative to a temporary protective structure, or to stabilize the soil in an excavation, tunnel or underground shaft. Section 443 (1) to (3).

Marking an Excavation

If there is a danger of a worker or equipment falling into an excavation, an employer must ensure that workers are made aware of the excavation through flagging, marking, safeguards, or other appropriate and effective means. Section 444.

Water Hazard

An employer must ensure that an excavation that a worker may be required or permitted to enter is kept free of an accumulation of water that may pose a hazard to the worker. Section 445.

Worker Access

(1) An employer must provide workers with a safe means of entering and leaving an excavation, tunnel or underground shaft.

(2) An employer must ensure that a worker does not enter an excavation, tunnel or underground shaft that does not comply with this Part.

(3) A worker must not enter an excavation, tunnel or underground shaft that does not comply with this Part. Section 446 (1) to (3).

For more information:

Locating Buried or Concrete‒Embedded Facilities. Section 447 (1) to (5).
Exposing buried facilities. Section 448 (1) to (7).
Section 449.
Methods of protection. Section 450.
Loose materials. Section 452.
Spoil piles. Section 453.
Safe entry and exit. Section 455 (1) (2).
Temporary protective structures. Section 456 (1) to (3).
Alternatives to temporary protective structures. Section 457 (1) to (5).
Installation of shoring, stringers or Section 458 (1) to (4).
Access for powered mobile equipment. Section 459.
Dumping block. Section 460.
Underground shafts. Section 461 (1) to (5).
Drilled or bored underground shaft. Section 462 (1) to (4).
Section 463.
Section 464 (1) (2).

Further details on the Occupational Health and Safety Code can be found at Alberta.Ca.

BRITISH COLUMBIA

In British Columbia, employers are required to ensure excavation safety under the Occupational Health and Safety Regulation Part 20, Sections 20.78 to 20.94. Employers must follow certified instructions from a qualified professional for deep or complex excavations, locate underground utilities before digging, secure or remove nearby hazards, and ensure proper sloping, shoring, or shielding to prevent collapse. They are also responsible for providing safe access and exit, guarding open excavations, maintaining clear distance for excavated materials, and positioning equipment to protect workers. These responsibilities are essential to minimize the risk of injury during excavation work.

Part 20: Construction, Excavation, and Demolition

Work Standards

(1) Subject to this section, excavation work must be done in accordance with the written instructions of a qualified registered professional if:

(a) the excavation is more than 6 m (20 ft) deep,

(b) an improvement or structure is adjacent to the excavation,

(c) the excavation is subject to vibration or hydrostatic pressure likely to result in ground movement hazardous to workers, or

(d) the ground slopes away from the edge of the excavation at an angle steeper than a ratio of 3 horizontal to 1 vertical.

(2) Despite subsection (1), excavation work described in that subsection must be done in accordance with the written instructions of a professional engineer if the excavation requires or uses support structures.

(3) The written instructions required by this section must:

(a) be certified by the qualified registered professional concerned,

(b) be available at the site, and

(c) specify the support and sloping requirements, and the subsurface conditions expected to be encountered. Section 20.78 (1) to (3).

Underground Utility Services

(1) Before excavating or drilling with powered tools and equipment, the location of all underground utility services in the area must be accurately determined, and any danger to workers from those utility services must be controlled.

(2) Excavation or drilling work in proximity to an underground utility service must be undertaken in conformity with the requirements of the owner of that utility service.

(3) Pointed tools must not be used to probe for underground petroleum and electrical utility services.

(4) Powered equipment used for excavating must be operated so as to avoid damage to underground utility services, or danger to workers. Section 20.79 (1) to (4).

Removing Nearby Hazards

Trees, utility poles, rocks and similar objects adjacent to an area to be excavated must be removed or secured if they could endanger workers. Section 20.80.

Sloping and Shoring Requirements

(1) Subject to section 20.78, before a worker enters any excavation over 1.2 m (4 ft) in depth or, while in the excavation, approaches closer to the side or bank than a distance equal to the depth of the excavation, the employer must ensure that the sides of the excavation are:

(a) sloped as specified in writing by a qualified registered professional,

(b) sloped at angles, dependent on soil conditions, which will ensure stable faces, but in no case may the slope or combination of vertical cut and slope exceed that shown in Figure 20-1,

(d) supported as specified in writing by a professional engineer,

(e) supported in accordance with the minimum requirements of section 20.85, or

(f) supported by manufactured or prefabricated trench boxes or shoring cages, or other effective means.

(2) If the end of a trench over 1.2 m (4 ft) in depth is not adequately sloped, end shoring must be installed unless:

(a) a worker in the trench is not required to approach closer to the end of the trench than a distance equal to the depth of the trench at that end,

(b) where, for the prevailing soil conditions at the end of the trench, the permissible spacing of uprights equals or exceeds the width of the trench, or

(3) If end shoring is required, the walers for the end shoring must be installed to bear against the walers that extend along the sides of the trench, or in a manner that will provide equivalent structural restraint.

(4) End shoring must be designed by a professional engineer if the end shoring waler length exceeds 1.8 m (6 ft).

(5) Shoring must extend from at least 30 cm (1 ft) above ground level to as close to the bottom of the trench as the material being installed will allow, but in no case more than 60 cm (2 ft) from the bottom.

(6) Shoring need not extend above ground level where traffic crossing plates need to be used, provided that other measures are taken to prevent excavated or other material from entering the excavation. Section 20.81 (1) to (6).

For more information:

Timber shoring and grades. Section 20.82.
Safe shoring procedures. Section 20.83.
Manufactured shoring. Section 20.84.
Trench support structures. Section 20.85.
Spoil piles. Section 20.86.
Entry and exit. Section 20.87.
Section 20.88.
Excavation crossings. Section 20.89.
Excavated materials. Section 20.90.
Use of skips or buckets. Section 20.91.
Scaling and trimming. Section 20.92.
Height limitations. Section 20.93.
Positioning equipment. Section 20.94.

Further details on the Occupational Health and Safety Regulation can be found at Worksafebc.Com

MANITOBA

In Manitoba, employers must follow Workplace Safety and Health Regulation Part 26, Sections 26.1 to 26.46 when performing excavation or trenching work. They are responsible for developing safe work procedures, training and supervising workers, notifying authorities, protecting against hazards like cave-ins and utility strikes, and ensuring safe access, support structures, and site guarding to keep workers safe.

Part 26 – Excavations And Tunnels

General Matters

Application

(1) Subject to subsection (2), this Part applies to every workplace where excavation work takes place.

(2) This Part does not apply to a mine as defined in The Mines and Minerals Act. Section 26.1 (1) to (2).

Safe Work Procedures

(1) An employer must:

(a) develop and implement safe work procedures for the work to be done at an excavation, including the installation, use, and removal of shoring;

(b) train workers in the safe work procedures; and

(2) Before any excavation work begins, an employer must ensure that workers are made aware of the potential hazards of the job functions they are to perform. Section 26.2 (1) to (2).

Registration

Registration Requirement

(1) In order to perform excavation work, an employer must:

(a) notify the branch that the employer intends to do excavation work; and

(b) receive a registration number from the branch.

(2) An employer must not begin any excavation work unless the employer has a valid registration number.

(3) A safety and health officer may revoke an employer’s registration number if the officer is of the opinion that the employer is performing excavation work in a manner that creates or may create a risk to the safety or health of a worker.

(4) When a registration number has been revoked, an employer may not be issued a new registration number unless a safety and health officer is satisfied that the employer will perform excavation work in accordance with the requirements of this Part. Section 26.3 (1) to (4).

Notification

Notice of Excavation

(1) An employer who proposes to make an excavation that is more than 1.5 m deep in which a worker is required or permitted to enter must notify the branch not more than 48 hours before the day that excavation work is scheduled to begin and provide the following information to the branch:

(a) the name and address of the owner of the land where the excavation is to be made;

(b) the name and address of the employer;

(d) the starting date of the excavation and its proposed completion date;

(e) the proposed depth, length and width of the excavation;

(f) a description of the proposed support structure, including the method of shoring and type of shoring materials, if shoring is to be used;

(g) verification that the owners of underground facilities have been notified and that the location of any pipes, conduits, or previous excavations in or adjacent to the proposed excavation site has been determined;

(h) the name of the person who will be supervising the work.

26.4(2) An employer required to notify the branch under this section must not begin excavation work until the branch has assigned a serial number to the excavation project.

26.4(3) This section does not apply to the digging of a burial lot or plot in a cemetery as defined in The Cemeteries Act. Section 26.4 (1) to (3).

For more information:

Sections 26.5.
Underground Facilities. Sections 6 (1) to (4).
Support Structure in Firm Contact. Section 23 (1) (2).
Deep Foundation Excavations. Sections 28 to 26.32.

Further details on The Employment Standards Code can be found at Canlii.org.

NEW BRUNSWICK

In New Brunswick, employers must follow General Regulation, Sections 180 to 193, when performing excavation and trenching work. Employers are responsible for identifying underground utilities, supporting trench walls through proper shoring or sloping, preventing water accumulation, ensuring atmospheric safety, and providing safe access. They must also protect workers from falling materials, vehicle hazards, and inadvertent entry by using barriers, illumination, and supervision.

XIII – Excavations and Trenches

Underground Utility Lines or Piping and Utility Poles

(1) Before beginning an excavation or trench, an employer shall ensure that the location of any underground utility line or piping is determined.

(2) Where employees are working within 600 mm of underground utility line or piping, an employer shall ensure that:

(a) the authority operating the utility line or piping has been notified of the operation,

(b) the utility line has been de-energized, and

(3) An employer shall ensure that utility poles, posts and similar structures are supported or removed if they are within 3 m of an excavation or trench that is more than 1.2 m deep. Section 180 (1) to (3).

Shoring, Bracing, or Caging of Walls

(1) An employer shall ensure that the walls of an excavation or trench are supported by shoring, bracing or caging except when the excavation or trench:

(a) is less than 1.2 m deep,

(b) subject to subsection (2), is cut in solid rock,

(c) is sloped or benched to within 1.2 m of the bottom of the excavation or trench with the slope or bench not exceeding 1 m of vertical rise to each 1 m of horizontal run, or

(d) is one that an employee is not required to enter.

Support of Unstable Walls Cut in Solid Rock

(2) Where the walls or crests of an excavation or trench are cut in solid rock and are not stable, an employer shall ensure that the walls and crests are adequately supported by rock bolts, wire mesh, shoring, or a method that provides equivalent support.

Support Where Heavy Equipment Used Near Edge

(3) Where powered mobile equipment or a mobile crane is used near the edge of an excavation or trench, an employer shall ensure that any shoring, bracing or caging for the excavation or trench is adequate to support the increased pressure.

Certificate of Engineer Respecting Support

(4) An employer shall ensure that shoring, bracing or caging for an excavation or trench is certified as adequate by an engineer and shall make the proof of the certification available to an officer on request. Section 181 (1) to (4).

Entering Excavation or Trench

(1) An employer shall ensure that an employee does not, and no employee shall, enter an excavation or trench 1.2 m or more in depth unless:

(a) the walls of the excavation or trench are supported by shoring, bracing or caging, the excavation or trench is cut in solid rock or the excavation or trench is sloped or benched to within 1.2 m of the bottom of the excavation or trench with the slope not exceeding 1 m of vertical rise to each 1 m of horizontal run,

(b) subsections 181(2), (3) and (4) have been complied with,

(d) a ladder that extends at least 1 m above the excavation or trench is installed no more than 15 m from where the employee is working or some other safe means of access and egress is provided.

(2) Notwithstanding subsection (1), an employee may enter an excavation 1.2 m or more in depth to install bracing if the employee remains a distance from the face of the excavation equal to or greater than the depth of the excavation.

(3) Notwithstanding subsection (1), an employer shall ensure that an employee does not, and no employee shall, enter an excavation or trench 1.2 m or more in depth to install or remove shoring or caging from a position inside an excavation or a trench. Section 182 (1) to (3).

Location of Excavated Material

(1) Subject to subsection (2), an employer shall ensure that excavated material is kept at least 1.2 m away from the edge of an excavation or trench. Section 183(2). Where an excavation or trench is more than 1.8 m deep in rock, an employer shall ensure that:

(a) excavated material is located back from the face of the excavation or trench a distance equal to at least the height of the excavated material, or

(b) a fence that is adequate to support the excavated material is erected at a minimum distance of 1 m from the face of the excavation or trench. Section 183 (1) (2).

For more information:

Water, testing for hazardous gas or oxygen deficiency, Storage of hazardous substance prohibited, Hazardous gases, and adequacy of ventilation. Section 184 (2) to (4).
Observation of employee working in excavation or trench. Sections 185.
Material lowered into excavation or trench. Sections 186, 187.
Illumination to prevent inadvertent entry, Barrier to protect workers. Section 188 (1) (2).
Protection of employees – rock face. Section 1.

XIV – Pits and Quarries

Section 189.

Further details on the General Regulation can be found at Laws.Gnb.Ca.

NEWFOUNDLAND & LABRADOR

In Newfoundland and Labrador, employers are required to address excavation and trenching safety under Occupational Health and Safety Regulations Part XVIII, Sections 404 to 413. Employers must ensure safe pre-excavation planning by identifying underground utilities, removing nearby hazards, and implementing protective systems like shoring, sloping, or trench boxes when workers enter excavations over 1.22 metres deep. Safe access and egress, proper storage of excavated material, atmospheric testing, and barriers to prevent falls are also required. Employers are responsible for protecting workers from cave-ins, hazardous gases, dust, and water accumulation, and must maintain air quality and ventilation, especially in underground work.

Part XVIII – Excavation, Underground Work and Rock Crushing

Definition

In this Part, “excavation” means a cut, cavity, trench or depression in the earth’s surface resulting from rock or soil removal. Section 404.

Entrapment Danger

(1) A worker shall not enter a place where there is a danger of entrapment unless safe access has been provided by catwalks, walkways or other acceptable means or the worker wears retrieval equipment satisfying the requirements of Part XXVII and is attended by another worker who is stationed, equipped and capable of immediately effecting a rescue.

(2) An area in which materials may be dropped, dumped or spilled shall be barricaded and protected by warning signs to prevent the inadvertent entry of workers. Section 405 (1) (2).

Pre-Excavation Requirements

(1) Before beginning excavation work with power tools or equipment in an area likely to have underground conduits, cables or pipelines, the location of the service facilities shall be accurately determined by the employer, marked by suitable means and communicated to the employee.

(2) Powered equipment shall not be used in a manner that exposes workers to harmful effects resulting from the damage to service facilities.

(3) Trees, boulders or other unsecured material located within 1.83 metres of the area to be excavated shall be secured or removed before excavation begins.

(4) A worker shall not enter an excavation over 1.22 metres deep unless:

(a) the sides of the excavation are sloped to a safe angle and have been secured by the use of sheet piling, shoring and bracing or a trench box; or

(b) the worker is protected by other effective means.

(5) Added loads shall be considered in the design of the support system where:

(a) equipment or other heavy objects are located or operated close to the edge of excavations;

(b) excavations are adjacent to or abutting buildings or other structures; or

(6) Where there is a danger of undermining adjacent foundations, excavation work shall be done in short sections and the building walls shall be effectively shored or braced. Section 406 (1) to (6).

Excavation or Access

(1) Where a worker is required to enter an excavation greater than 1.22 metres deep, a ladder shall be provided in the immediate area where the worker is employed, extending from the bottom of the excavation to at least 0.91 metres above the top of the excavation.

(2) Walkways entering excavations shall be:

(a) not less than 50.80 centimetres wide;

(b) equipped with guardrails when over 1.22 metres above grade; and

(3) A runway which is used by mobile equipment shall be equipped with curbs. Section 407 (1) to (3).

Removal of Material

(1) A worker shall not permit excavated material to remain:

(a) within 1.22 metres of the edge of a trench-type excavation; or

(b) within 1.52 metres of the edge of a pit-type excavation.

(2) Where skips or buckets are used to remove material from excavations, a horizontal shoring member shall be protected against dislodgement by the installation of vertical planking. Section 408 (1) (2).

For more information:

Faces and slopes. Section 409 (1) to (4).
Excavation safety. Section 410 (1) to (3).
Underground workings. Section 411.
Internal combustion engines. Section 412.
Air quality. Section 413 (1) to (11).

Further details on the Occupational Health and Safety Regulations can be found at Assembly.Nl.Ca.

NOVA SCOTIA

In Nova Scotia, employers must address excavation and trenching safety under the Occupational Safety General Regulations Part 14, Sections 166 to 173. They are responsible for ensuring that excavations over 1.2 m deep are properly supported with shoring, bracing, or trench cages unless exempted. Employers must also provide safe access, keep excavated material at a safe distance, control water and hazardous atmospheres, and install barriers to prevent falls. Support systems and trench cages must be certified by engineers and inspected daily by a competent person to ensure worker safety.

Part 14 – Excavations and Trenches

(1) Where a person may enter an excavation or trench and a wall of an excavation or trench is greater than 1.2 m in height, an employer shall ensure that the wall is supported by adequate shoring or bracing, or that an adequate trench cage is used, except where the employer is able to establish that the excavation or trench:

(a) is cut in sound and stable rock;

(b) is sloped

(i) to within 1.2 m of the bottom of the excavation or trench, or

(ii) where soil overburden is located above an excavation or trench excavated in sound and stable rock, for the entire overburden, and the slope does not exceed 1 m of vertical rise to each 1 m of horizontal run; or

(c) is one that a person does not enter within a horizontal distance from the walls of the excavation or trench that is equal to the height of the walls.

(2) Where the walls or crests of an excavation or trench are cut in rock, an employer shall ensure that the walls and crests are adequately supported by rock bolts, wire mesh or other means of adequate protection, if necessary, to ensure safe working conditions.

(3) Where powered mobile equipment is used near the edge of an excavation or trench, an employer shall ensure that any shoring, bracing or caging for the excavation or trench is adequate to support the increased load.

(4) An employer shall ensure that the walls of an excavation or trench are stripped of loose rock or other material that could slide, roll or fall on a person in the excavation or trench and injure that person.

(5) Despite clause (1)(b), an employer may slope the walls of an excavation or trench at an angle that exceeds a 1 m vertical rise to each 1 m horizontal run where an engineer has certified in writing that the steeper slope will be stable and is not a hazard to a person in the excavation or trench.

(6) An employer shall ensure that a utility pole, building or other structure is provided adequate support or removed if the utility pole, building or other structure may become unstable because of excavation or trenching activity. Section 166 (1) to (6).

No person shall enter an excavation or trench 1.2 m or more in depth unless an employer ensures that a ladder is installed that extends at least 1 m above the excavation or trench or some other adequate means of access and exit is provided:

(a) that is no more than 15 m from where the person is working; or

(b) where a trench cage is used, within the trench cage. Section 167.

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. Section 168.

(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

(b) adequate precautions are taken to reduce the risk of injury to a person.

(3) No person shall store hazardous substances in an excavation or trench.

(4) An employer shall provide, at or near the sides of all temporary excavations greater than 1.2 m in depth, fences, guards or barricades that prevent a person from falling into an excavation, and shall keep those fences, guards or barricades in place at all times, except where they interfere with the excavation or other work being done. Section 169 (1) to (4).

For more information:

Engineer Design Certification of trench cage. Section 170 (1) to (4).
Permanently Attached of Nameplate in Trench Cage. Section 171 (1) (3).
Trench cage positioning in excavation or cage. Section 172.
Shoring or bracing In Certification Compliance. Section 173.

Further details on the Occupational Safety General Regulations can be found at Novascotia.Ca.

NORTHWEST TERRITORIES

In the Northwest Territories, employers must follow the Occupational Health and Safety Regulations Part 17, Sections 264 to 269, 271, 272 when performing excavation or trenching work. They are responsible for locating and marking underground utilities, preventing cave-ins with proper sloping or engineered protective systems, and keeping excavation areas clear of water and loose material. For excavations over 1.2 m deep, employers must provide safe access and ensure structures nearby are supported. Additional safety measures apply to shafts, tunnels, and boreholes to protect workers from collapse and falling materials.

Part 17 – Excavations, Trenches, Tunnels, and Excavated Shafts

Application of Part

This Part applies to excavations, trenches, tunnels, excavated shafts and bore holes. Section 264.

Locating Underground Pipelines

(1) An employer shall accurately establish the location of all underground pipelines, cables and conduits in an area where work is to be done and shall ensure that those locations are conspicuously marked:

(a) before commencing work using power tools or powered mobile equipment on an excavation, trench, tunnel, excavated shaft, or borehole; or

(b) before breaking ground surface with any equipment that could contact underground utilities.

(2) If an operation is to be undertaken involving the disturbance of soil within 600 mm of an area of an existing pipeline, cable or conduit, an employer shall ensure that the pipeline, cable or conduit is exposed by hand digging or other approved method before mechanical excavating is allowed to begin within that area.

(3) If an operation referred to in subsection (2) exposes a pipeline, cable or conduit, an employer shall ensure that the pipeline, cable or conduit is supported to prevent damage during backfilling and any subsequent settlement of the ground.

(4) If there is contact with or damage to an underground pipeline, cable or conduit, an employer shall, without delay,

(a) notify the owner of the pipeline, cable, or conduit that contact or damage has occurred; and

(b) take steps to protect the health and safety of workers who could be endangered until any unsafe condition resulting from the contact or damage is repaired or corrected. Section 265 (1) to (5).

Excavating and Trenching

(1) An employer shall ensure that:

(a) before excavating or trenching begins, if the stability of a structure could be affected by an excavation or trench, the structure is supported by a temporary protective structure designed by a professional engineer and constructed, installed, used, maintained and dismantled in accordance with that design;

(b) all loose material is scaled or trimmed from the side of an excavation or trench where a worker is required or permitted to be present;

(c) equipment, spoil piles, rocks, and construction materials are kept not less than 1 m from the edge of an excavation or trench;

(d) an excavation or trench that a worker could be required or permitted to enter is kept free from accumulation of water; and

(e) the slope of a spoil pile adjacent to an excavation or trench has a slope at an angle not steeper than one horizontal to one vertical, or 45º measured from the horizontal.

(2) Subject to subsections (3) and (4), if a wall of an excavation or trench is cut back, an employer shall ensure that:

(a) in the case of type 1 or type 2 soil, the walls are sloped to within 1.2 m of the bottom of the excavation or trench, with a slope at an angle not steeper than one horizontal to one vertical, or 45º measured from the horizontal;

(b) in the case of type 3 soil, the walls are sloped from the bottom of the excavation or trench, with a slope at an angle not steeper than one horizontal to one vertical, or 45º measured from the horizontal; and

(c) in the case of type 4 soil, the walls are sloped from the bottom of the excavation or trench, with a slope at an angle not steeper than three horizontal to one vertical, or 19º measured from the horizontal.

(3) If an excavation or trench contains more than one type of soil, the soil must be classified as the soil type with the highest number.

(4) Subsection (2) does not apply to an excavation or trench that is cut in sound and stable rock.

(5) If an excavation or trench is to be made in the vicinity of an overhead power line pole, an employer shall ensure that the work is carried out in a manner that will not reduce the original support provided for the pole, unless permission has previously been obtained from the utility company responsible for the overhead power line.

(6) An employer shall ensure that none of the following is operated or located near an excavation or trench so as to affect the stability of the walls of the excavation or trench:

(a) a unit of powered mobile equipment;

(b) a vehicle of any type;

Frozen Soil

If an excavation, trench, tunnel, excavated shaft or borehole is made in proximity to or into frozen soil, an employer shall take measures to preserve the adjacent frozen soil. Section 267.

For more information:

Temporary Protective Structures. Section 268 (1) to (4).
Protection Against Cave-In of Excavations. Section 269 (1) to (3).
Excavated Shafts and Tunnels. Section 271 (1) to (3).
Boreholes, Belled Areas of Excavated Shafts. Section 272 (1) to (3).

Further details on the Occupational Health and Safety Regulations can be found at Canlii.Org.

NUNAVUT

In Nunavut, employers must follow the Occupational Health and Safety Regulations Part 17, Sections 264 to 269, 271, 272 when performing excavation or trenching work. They are responsible for locating and marking underground utilities, preventing cave-ins with proper sloping or engineered protective systems, and keeping excavation areas clear of water and loose material. For excavations over 1.2 m deep, employers must provide safe access and ensure structures nearby are supported. Additional safety measures apply to shafts, tunnels, and boreholes to protect workers from collapse and falling materials.