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These materials will help you learn more about safe digging.

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Information and Resources

There are dangers under the ground

There are numerous underground hazards that could cause serious injuries. Hitting gas, electric, or other high-pressure pipes and lines could have fatal consequences.
We must all prevent damages to protect our communities.

Never assume it is safe to dig

  • Nicking a gas line could lead to leaks, fire, or explosions.
  • Damaging electrical cables could shock or electrocute you.
  • Hitting water or sewer lines could cause flying debris, floods, contamination, and environmental hazards.
  • Cutting telecommunications cables could disrupt internet or cable services and your ability to call 911 in an emergency.

To dig safely, excavators must first obtain a locate by contacting Ontario One Call, then follow the written instructions provided with each locate response, and follow best practices as outlined in the Canadian Common Ground Association’s (CCGA) Underground Infrastructure Damage Prevention Best Practices.

Anyone not following safe digging practices, and who hits underground infrastructure could be held liable for damages. Charges and fines could also be laid by the Ministry of Labour and the Technical Standards and Safety Authority (TSSA).

Despite these penalties, the Ontario Regional Common Ground Alliance’s (ORCGA) DIRT Report found that there were 4,940 reported damages to underground cables, pipes, and lines in 2019. 41% of the damages were caused by improper excavation practices, and 36% were caused because a locate was not requested.

damaged pipe
get the dirt on all digs graphic
bursting pipe

Damage to underground infrastructure is preventable

Always Click Before You Dig and follow safe digging practices.

Want to know more about underground infrastructure damages in Ontario?

Read the latest DIRT Report by the ORCGA.

2020 Dirt Report Cover

Preventing damages and digging safely

Read the latest CCGA Underground Infrastructure Damage Prevention Best Practices.

CCGA Cover

What do the coloured marks mean?

Each type of infrastructure has an universal colour code to help identify them.
Field locates can be made in various ways including paint, stakes or flags.

<p><strong>Red</strong><br />


<p><strong>Yellow</strong><br />


<p><strong>Orange</strong><br />


<p><strong>Green</strong><br />


<p><strong>Blue</strong><br />


<p><strong>Purple</strong><br />


<p><strong>Pink</strong><br />
Temporary Survey Markings</p>

Temporary Survey Markings

<p><strong>White</strong><br />
Proposed Excavation</p>

Proposed Excavation

Ontario One Call handles the notification for almost all of the buried infrastructure on public property (exceptions could include some first nations, provincial and federal entities.) This infrastructure is owned and maintained by organizations like public utility companies and runs through the public right of way and on to some private property up to a demarcation point, that varies from each utility owner. Public property lines differ per municipality, make sure to check your local rules.

All other buried infrastructure (including buried infrastructure beyond the demarcation point) on private property is the responsibility of the property owner to have marked.

Examples could include:

  • Gas line that goes from a house to a BBQ or pool heater
  • Lights or signs on the property
  • Electrical lines going out to sheds or a detached garage
  • Sewer and septic tanks, systems and piping
  • Security cameras

This image shows some examples of properties with public infrastructure shown in solid lines and private infrastructure shown in dashed lines.

To get your private lines marked, a competent private locator must be hired.

property line graphic

Call Before You Clear

It’s rare, but it is possible, that a natural gas line was unintentionally installed through a sewer line. Be safe, if you have a backed-up sewer call Ontario One Call at 1-800-400-2255 before you or a plumber attempts to clear the line. you need to know before clearing your sewer line

It’s free. It’s easy. It’s safe.


illustration of sewer pipe with intersecting natural gas line

Sewer blockages
could be caused by
intersecting gas lines

Alternative Locate Agreement – for contractors and underground infrastructure owners

Buried infrastructure owners wishing to opt out of notification from a certain excavator for specific types of work/method of digging may wish to set up special arrangements with the excavator through an Alternate Locate Agreement or Suppression.

An Alternate Locate Agreement (ALA) advises the excavator that a traditional field locate from the Ontario One Call member is not required. This could be for work that is deemed low-risk to the member’s infrastructure (i.e. hand digging tree roots, vacuum excavation, etc.). When the excavator contacts Ontario One Call using a special Contractor ID, the member in question does not receive the locate request instead the notification system will advise the excavator that traditional field locates will not be completed under their ALA.

An ALA has to be pre-arranged with an owner of buried infrastructure (Member). The member will contact Ontario One Call to request a Contractor ID to be associated with an ALA.

contractor in dirt pit