Striking underground utilities or other buried facilities can lead to serious, even deadly, consequences.  Poor planning, lack of awareness or improper regard for safe work practices around buried facilities could lead to hits with various results: service disruptions, evacuations, release of product or energy, environmental damage, costly repairs and lawsuits, injuries or loss of life to name a few.  Incidents can be avoided when ground disturbance practices are carefully planned and followed.

 What is a Ground Disturbance?
In general terms, a ground disturbance is a task which involves moving or penetrating the ground surface. It includes not only mechanical excavation, but activities such as driving posts or stakes, drilling, digging, trenching, blasting, and others. 

> Alberta’s Pipeline Act defines ground disturbance as: “any work, operation or activity that results in a disturbance of the earth including, without limitation, excavating, digging, trenching, plowing, drilling, tunnelling, augering, backfilling, blasting, topsoil stripping, land levelling, peat removing, quarrying, clearing and grading, but does not include,

except as otherwise provided in subclause (ii), a disturbance of the earth to a depth of less than 30 centimetres that does not result in a reduction of the earth cover over the pipeline to a depth that is less than the cover provided when the pipeline was installed,

cultivation to a depth of less than 45 centimetres below the surface of the ground, or

any work, operation or activity that is specified in the regulations not to be a ground disturbance”.

> Ground disturbance is defined differently in the Occupational Health & Safety Code (Alberta).  Part 32 of the OH&S Code, on excavation and tunneling, states: “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, or

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

Other regulations have different applications or definitions of ground disturbance.

What Types of Infrastructure Might Be Underground?

• Oil and gas pipelines
• Storage tanks and piping for chemicals and petroleum products
• Water and sewage lines
• Steam lines
• Telecommunications cable and equipment
• Electrical energy

How Can A Ground Disturbance Be Carried Out Safely?

This article provides only a brief introduction.  Preparation for a ground disturbance requires careful planning, sufficient time, the right resources, and adherence to established safe work practices.  Several excellent references are listed below.

Here are some common practices to be carried out before initiating a ground disturbance.

• Conduct a records search.  Review site drawings, land titles, crossing agreements, and other legal documents which might identify the existence and locations of buried facilities in the area to be disturbed - and beyond.  For example, any pipelines within 30 metres of the proposed disturbance must be identified.
• Determine which regulations apply to the proposed ground disturbance.
• Notify the owners of buried facilities, and obtain permission for the ground disturbance.  Notification times vary, but are usually from two to ten days prior to the proposed disturbance.  Many provinces, including Alberta, have a One-Call System which can be used to notify registered members.  However, not all buried facility owners are registered with one-call; you must contact non-registered members directly.
• Conduct a visual inspection of the area to be disturbed.  Look for signs of buried facilities and previous ground disturbances.  Also identify overhead power lines that could pose a hazard during site activities.
• Locate, map and mark buried facilities.  The owner of buried facilities, or a third party company, will usually undertake this.  Facilities must be marked according to a standardized colour-coding system (see sidebar).
• Pipelines and other underground facilities are to be exposed by hand. Typically, ground within one metre to 5 metres of the buried facility will have to be hand exposed prior to mechanical excavation.  Specific procedures will vary, depending on the type of buried facilities present and which regulations or agreements are in force.
• Respect all specified clearance distances between mechanical excavation equipment and buried facilities.  Remember to maintain safe distances from overhead lines as well.
• In some cases, the owners of buried facilities must be notified and/or must inspect exposed facilities before they are backfilled.
• Appoint a competent supervisor to oversee all ground disturbance activities.  Also, personnel directly involved in ground disturbance activities should be adequately trained on ground disturbance procedures and site-specific conditions.
• Maintain all records required by applicable regulations and legal agreements.

Colour Code for Marking Buried Facilities

APWA – American Public Works Association* ^{1, 2, 6}

Paint, flags or stakes may be used to identify underground facilities.

Note:  Geophysical operations do not follow APWA colour codes.

Useful References:

1. “The Damage Prevention Process in Alberta: Roles, Responsibilities and Expectations of the Stakeholders in the Prevention of Damage to Buried Facilities”, Alberta Utility Coordination Council, Alberta Chapter of the Canadian / American Public Works Association, Issue No. 1, 23 March 2005.
2. “Ground Disturbance in the Vicinity of Buried Facilities”, Industry Recommended Practice (IRP) Volume 17 – 2004, Enform
3. “Excavation and Construction Near Pipelines”, National Energy Board, 2005.
4. “Homeowner Safety: Working Around Natural Gas Pipelines”, Atco Gas.  A PDF version of this pamphlet is available at www.atcogas.com
5. EUB Guide 30: “Guidelines for Safe Construction Near Pipelines”, Alberta Energy Utilities Board.  A PDF version is available at http://www.eub.ca/docs/products/guides/g30.pdf
6. Alberta One-Call Corporation:  Toll-Free Telephone 1-800-242-3447; Website www.alberta1call.com