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Blitz Results: Excavation Hazards

Safe At Work Ontario
  • Issued: July 30, 2014
  • Content last reviewed: July 2014

Hazards involving excavations can lead to serious incidents involving workers at construction projects.

Excavations are holes in the ground created as a result of removing material. Generally, an excavation is dug in the earth to install utilities such as sewers, water mains and gas supplies, or to construct foundations for buildings or other structures. This includes excavations of trenches along existing rights of way on roads.

In May 2014, the Ministry of Labour targeted excavation hazards during an enforcement blitz at construction projects across Ontario.

Construction inspectors checked on compliance with the Occupational Health and Safety Act (OHSA) and its regulations. They checked for safety issues involving:

  • excavation and trenching support systems
  • utilities locations
  • measures to prevent workplace incidents

The goals of the blitz were to:

  • raise awareness of hazards involving excavations at construction projects
  • increase worksite compliance with the law
  • prevent injuries that could arise from unsafe work practices

Report summary

In May 2014, ministry inspectors conducted 1,094 field visits to 957 workplaces and issued 2,191 orders under the OHSA, including 186 stop work orders. Some of the workplaces were visited more than once.

Of the orders:

Of those orders, the three most frequently issued orders involved a failure of employers to ensure:

  • excavations were in compliance with proper support systems
  • workers were wearing personal protective headwear
  • adequate emergency procedures were in place

Full report

Inspection blitzes are part of the province's Safe At Work Ontario compliance strategy. They are announced to the sector by the ministry in advance, although individual workplaces are not identified in advance. Results are posted on the ministry's website. The blitzes raise awareness of workplace hazards and are intended to promote compliance with the OHSA and its regulations.

Inspectors' findings may impact the frequency and level of future inspections of individual workplaces. Inspectors may also refer employers to health and safety associations for compliance assistance and health and safety-related training.

Blitz focus

The scope of the campaign was comprehensive and included all types of excavation hazards at Ontario construction projects.

Inspectors focused on the following key priorities:

Excavation wall support

Inspectors checked that:

  • excavation and trenching support systems were in place
  • employers were determining the site's soil type to ascertain the strength and stability of the excavation walls
  • trench and excavation walls were being stripped of any loose rock or other material that could slide, roll or fall on a worker
  • constructors were taking appropriate precautions to prevent damage to nearby structures, including employing a professional engineer to specify in writing any precautions to be taken
  • there was safe access and egress available to workers
  • no workers were working alone

Utilities locations

Inspectors checked that:

  • employers identified, located and marked utilities to prevent worker contact with gas lines, electrical conductors and other services during excavations
  • utility owners were being asked to supervise the uncovering of potentially hazardous utilities if the services could not be disconnected during the excavation

Safety measures

Inspectors checked that:

  • employers had measures and procedures in place to prevent slips, trips and falls hazards
  • a barrier at least 1.1 metres in height was provided, when required, at the top of an excavation if it did not meet regulatory slope requirements and was more than 2.4 metres deep
  • a clear work space of at least 450 millimetres was maintained between the excavation's wall and any work platform

Inspection activity summary

Table 1: Inspection visits to Construction Projects
Program Activities Number
Field visits 1,094
Number of workplaces visited 957
Orders issued [1] 2,191
Stop work orders 186
Requirements 45
Orders and requirements per workplace visited 2.29
Orders and requirements per visit 2

[1] Requirements and stop work orders are part of the total orders issued

Order analysis

Excavation incidents continue to be a safety issue at Ontario construction projects.

Of the 2,191 total orders issued during the blitz:

Table 2: Excavation-related orders under Regulations for Construction Projects [2]
Reason for Order Number of Orders Percentage of Total [3] Orders
Excavation safety (Sections 222-242) 211 9.63%
Access and egress to work area (Sections 70-84) 176 8.03%
Fall protection hazard (Section 26) 167 7.62%
Registration and notices (Section 5-6) 127 5.80%
Personal protective equipment (Sections 21-25) 126 5.75%
Construction equipment hazards (Sections 93-116) 116 5.29%
Emergency procedures (Section 17) 104 4.75%
Traffic protection inadequate (Section 67-69) 71 3.23%
Fire safety (Section 52-55) 52 2.37%
Housekeeping concerns (Section 35) 19 0.87%
[2] Contains a sampling of the most common excavation-related order sections
[3] All orders, including those under OHSA and the Regulations for Construction Projects


During the blitz, 548 orders were issued under the OHSA. Of those, 186 (34 per cent) were stop work orders.

However, the number of excavation-related orders and requirements (per workplace visited and per field visit) are down, as compared to orders issued during a 2013 excavation blitz.

This reduction is a positive sign of improved industry awareness and compliance, but work still needs to be done.

Table 3: Excavation blitz comparison 2013 vs. 2014
Program Activities 2013 2014
Orders and requirements issued per workplace visited 2.50 2.29
Orders and requirements issued per visit 2.26 2.00

The most frequently issued orders in the 2014 blitz were under excavation-related Sections 222 to 242 in the Constructions Regulations. The most common order was for violations of the excavation support systems (Section 234) involving design and specifications, type of support systems used, professional engineer requirements and access and egress.

In the 2014 blitz, there was an increase in violations involving a lack of emergency plans and procedures being developed by employers to protect workers (Section 17). There were 104 orders issued in the 2014 blitz, as compared to 87 orders in the 2013 blitz. This section was one of the top three orders written during the 2014 blitz.

About 98 per cent of orders in the 2014 blitz were issued to constructors or employers involving their OHSA duties.

The results also show that focusing enforcement on the internal responsibility system continues to be a priority.

Next steps

The results of this blitz verify the need to continue focused enforcement activity in the above-noted areas.

Inspectors will continue to focus on excavation hazards that may put workers at risk of injury.

Compliance help for employers

For more information on identifying, preventing and controlling these hazards, please contact Ministry of Labour safety partners.