The Definition of Ground Disturbance

Definition of Ground Disturbance

Ground disturbance is any work, operation or activity that breaks or moves the ground and could damage buried infrastructure such as pipelines, power cables or communication lines. Digging, trenching, augering, drilling, plowing, grading, blasting, stripping topsoil and driving fence posts all count.

The term is mostly Canadian and comes from the oil and gas and pipeline sectors, where striking a buried line can cause a fire, an explosion, a toxic release or an outage across a region. In the US, the same work is usually discussed as excavation and damage prevention, with the national 811 "call before you dig" system at its center. The underlying problem is identical on both sides of the border: you cannot see what is under the ground, and old drawings are often wrong.

How Ground Disturbance Is Regulated in Canada

Alberta pipeline rules

Alberta's Pipeline Act and Pipeline Rules, overseen by the Alberta Energy Regulator (AER), set out what counts as ground disturbance near pipelines. Regulator guidance lists activities from excavating and trenching to quarrying, clearing and pounding posts. It excludes disturbance less than 30 cm deep that does not reduce the pipeline's earth cover below its original depth, and normal cultivation no deeper than 45 cm. Anyone planning ground disturbance within the controlled area, which extends 30 m on each side of the pipeline centerline, must follow notification and supervision requirements.

Federally regulated pipelines

For interprovincial pipelines regulated by the Canada Energy Regulator (CER), ground disturbance of 30 cm or deeper within the prescribed area, 30 m on either side of the pipe centerline, requires consent from the pipeline company. After a locate request through a one-call center, the pipeline company must mark its line within 3 working days or a mutually agreed time.

The national standard

CSA Z247, Damage prevention for the protection of underground infrastructure, is the Canadian consensus standard for planning, locating, excavating and backfilling around buried facilities. It applies across utilities and industries, not only oil and gas, and many owners and municipalities write it into their requirements.

Steps Before the First Shovel

1. Plan the work area. Define the full footprint of the disturbance, including spoil piles, equipment travel and any area to be graded.
2. Request locates. In Alberta, submit a request through Utility Safety Partners (formerly Alberta One-Call). Elsewhere in Canada, use the provincial one-call service, often branded Click Before You Dig. In the US, call or click 811. AER guidance also tells excavators to contact pipeline owners at least two full working days before digging and to search 30 m beyond the perimeter of the dig area.
3. Check records. One-call centers only notify their members. Private lines, such as plant-owned process piping, private power or old abandoned lines, may not be on the list. Check the site's own drawings and ask the landowner or facility owner.
4. Confirm marks on site. Walk the area with the locate sheet. Make sure every listed facility is marked or cleared, and that marks match the drawings.
5. Issue a permit. Most operators require a ground disturbance checklist or permit to work signed by a trained supervisor before digging.

Digging Near Buried Facilities

Hand exposure and hydrovac

Locate marks show approximate position, not exact depth or alignment. That is why rules require the facility to be exposed by non-mechanical means before machines work close to it. For Alberta pipelines, AER guidance calls for hand exposure within 5 m of the pipeline before machinery is used, and no machinery within 60 cm of the pipeline, or anywhere beneath it, without the pipeline owner's supervision. Hydrovac excavation, using pressurized water and vacuum, is widely used to expose lines safely and quickly.

Tolerance zones

Most damage prevention rules define a tolerance or hand-dig zone on each side of a located facility, inside which mechanical digging is not allowed until the facility is exposed. The width depends on jurisdiction and facility owner. Check the locate sheet and the owner's requirements rather than assuming a single number.

Electrical and gas strikes

Contacting a buried power cable is an electrical hazard for the operator and anyone touching the machine. Hitting a gas line can release flammable gas into the trench. Emergency plans should spell out what to do: stop, keep people back, do not try to fix the damage, and call the owner and emergency services.

Training and Competence

Industry training in Canada is commonly split into two levels. Level 1, sometimes called worker or awareness level, covers basic hazards, locates and safe digging. Level 2, often branded Ground Disturbance 201 or supervisor level, prepares supervisors and equipment operators to plan the work, interpret locates, complete checklists and oversee exposure. Pipeline operators and many owners require a Level 2 trained supervisor on site for any ground disturbance near their facilities.

Training is not the same as competence. The supervisor should be a competent person who knows the site, the drawings and the limits of the locate. When outside excavation crews are hired, prequalification through a contractor safety program should confirm their ground disturbance training and track record.

Example of Ground Disturbance

A contractor installing new fence posts around a gas compressor station in central Alberta submitted a locate request, received clearances, and started augering. On the third post, the auger struck an unmarked 25 mm steel line. It turned out to be a disused instrument air line belonging to the facility, not on the one-call system because it was a private line.

Nobody was hurt, but it could easily have been a live fuel gas line. The facility owner changed its procedure. Ground disturbance permits now require a review of plant drawings and a private locate by a contracted locating company for anything inside the fence line, in addition to the one-call request. Post holes within 5 m of any known or suspected line are now daylighted by hydrovac before augering.

Frequently Asked Questions: Ground Disturbance

Does hand digging count as ground disturbance?

Yes, if it meets the depth threshold for the jurisdiction. Shallow work like planting flowers is generally excluded, but digging a post hole by hand to 30 cm or more near a pipeline usually counts. Hand digging is the safer method near facilities, not an exemption. Locates are still required, and the hole can still hit a shallow cable.

How long are locates valid?

It depends on the one-call center and facility owner. Locates commonly expire after a set number of days, and they must be refreshed if marks are destroyed, the work scope changes or work stops for a period. Check the expiry date printed on the locate sheet and do not dig past it. Faded or disturbed marks should be re-marked before work continues.

Is ground disturbance training required by law?

In most provinces, legislation requires employers to train and supervise workers adequately, without naming a specific course. The Level 1 and Level 2 ground disturbance courses are industry requirements set by pipeline operators, owners and clients. In practice, crews without them often cannot work on oil and gas or pipeline sites, so they function as a condition of access.

What is the US equivalent of ground disturbance?

In the US, the work is generally called excavation, and damage prevention is governed by state one-call laws. Excavators call 811 or submit an online request a few business days before digging, and utilities mark their lines. Trench and excavation safety for workers is covered separately by OSHA's construction standards in 29 CFR 1926 Subpart P.