Ground Disturbance

Posted: Feb. 15, 2019 • By Kevin Kohler

Ground Disturbance

Can ground disturbance be dangerous?

40 years ago on March 2nd 1979 an excavation contractor working in a new Edmonton, Alberta neighborhood hit a high pressure propane gas line causing an explosion and fire. Propane leaked into sewers and people’s toilets. Ultimately 19,000 people had to be evacuated and at the time it was the largest peacetime evacuation in Canadian history.
There are still thousands of underground utility infrastructure strikes reported each year in Alberta.

What is “Ground Disturbance”?

Ground Disturbance generally means any work or activity that results in the earth being disturbed. This includes such activities as excavating, digging, trenching, drilling, auguring, backfilling, blasting, topsoil stripping, land leveling, clearing, and grading. The ground can be disturbed in many more ways than just by digging.

“Ground disturbance” activities are subject to permitting and are regulated through safety legislation and the legislation governing utilities and pipelines

We have many underground services or “facilities” installed right under our feet, and we keep installing more and more of these each year. What types of “facilities” should we be worried about? It’s a long list, and includes:

• Electrical cables
• Oil, gas and chemical pipelines
• Communication, signal and data cables
• Water and sewer lines
• Underground vessels

What are the Hazards?

Damage to some of these facilities may not result in anything as spectacular as a explosion, but in an automated and interconnected world it can seriously compromise safety in ways we may not think of, such as by affecting critical data and communications that we rely on to keep our highways, transit systems, hospitals and public services safe and functioning.

Some critical work sites (chemical facilities, waste management facilities, transportation hubs, etc.) may have very stringent ground disturbance requirements that exceed regulatory requirements because of their risk profile.

How do we plan Ground Disturbances?

When planning for a ground disturbance activity, always refer to an established ground disturbance checklist, such as the “InUnison Ground Disturbance Checklist” before beginning any work. The checklist is meant to remind you of all of the steps required to control the hazards posed by ground disturbance. These steps can include:

• Training for supervisors and workers
• The locating process to be used or all underground facilities
• The required permits and safe work permits
• Pre-job hazard assessments and safety meetings
• Establishing emergency response procedures
• Backfill requirements and inspections
• Safe approach limits to overhead and buried electrical cables and equipment
• Coordination with underground facility owners
• Written work plans

What is One Call?

In Canada there is a network of underground utility owners and operators that operate under common “ground alliances”. These alliances sponsor government sanctioned “One Call” centers that coordinate line location requests by province. Locating underground services before you begin work is a legislated requirement.

Not all underground facilities are registered under “One Call”, you should also refer to:
• Signs or markers in the area.
• Other national or local regulators (energy boards, rural utility associations)
• Land Titles offices for easements and right of ways
• Local landowners, facility owners or occupants.
• Any other evidence you see indicating likely underground facilities

On private sites you must work very closely with the owner or person-in-charge of the site to take all measures to verify the underground facilities present. This may require extensive safe exposure methods where there is no information, such as “daylighting” with high pressure water.

We must be aware of our safety responsibilities when disturbing the ground. What we can’t see can most certainly hurt us and others!


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