March 31/10

Terasen Inc. A Fortis company.

BC Common Ground AllianceDig Safe BC, Cranbrook

Safe Excavation Practices when working around Distribution Gas Lines & IP/ TP Pipelines

Maple Heights - Distribution Damage

Midwest USA - 2008

Regulations in B.C.

• Pipeline Act & Regulations• Enforced by the Oil & Gas Commission• Administered by the Pipeline Company

(Terasen Gas)• The purpose is to ensure everyone’s

safety. The specification of the pipe materials, installation, maintenance frequencies and keeping the pipe safe from potential damage.

Terasen’s Standard Process

• All pipelines with pressure over 100 psig• A call to BC One Call begins the process• Information on line location is forwarded • Terasen’s Permit Desk will call requesting details• Activities within 30 metres of the pipeline:

• Terasen will electronically locate running line of pipeline

• Depending on your activities a Terasen Inspector may monitor the work

• Locate and confirm the location of pipe by non-mechanical means

• Hand dig only within 1 metre either side of the pipeline

Regulations in B.C. (con’t)

• The following provisions apply to the crossing of pipelines by any highway, private road, railway, utility line, drain or other company pipeline: • (G) before any work of construction, maintenance,

renewal or repair of any crossing of a pipeline is begun, the authority having control over such crossing or the party making, owning or operating such crossing, as the case may be, must give to the pipeline company at least 48 hours notice in writing, to enable the pipeline company to appoint an inspector to see that the work is performed in such a manner as will in all respects comply with this regulation; and in cases of emergency the pipeline company must be notified immediately

WorkSafe BC Regulations

• WorkSafe BC Regulations – include Notice of project forms for excavations over 4ft in depth and 100ft in length. (20.2) (1) (f)

• A “bell hole” is considered a trench as long as the width at the bottom doesn’t exceed 12ft . (20.1)

Planning an Excavation

• Call BC 1 Call

• All above and below ground Utilities.

• Other hazards including onsite physical evidence of recent activity

• Site congestion - traffic, spoil pile, material removal and delivery all need to be planned in advance.

Planning an Excavation

• Proximity to adjacent roads, sidewalks, retaining walls, building foundations

• Soil condition, type and strength

• Surface and groundwater

• Weather

• Size and type of bucket

• The reach of your machine

Worksite Safety and Access

• Your excavation work must be performed to ensure Public Safety and Access.

• Use of barricades, flashers, temporary bridging and appropriate lighting may be required.

• Use of a screen to prevent rocks kicked out by passing vehicles tires from entering the excavation.

Worksite Safety and Access

• Excavated spoil may be used as a barricade where practical.

• The spoil must be kept back a minimum of 2 ft from the edge of a trench excavation and 4 ft from any other excavation.

• Site congestion – traffic, spoil pile, material removal, delivery all need to be planned in advance

Common Excavation Problems

• Inadequate sloping or shoring of excavation sides

• Lack of shoring knowledge• Poor maintenance of shoring• Defective shoring materials• Excavated material is too close to the

excavation’s edge• Undercutting of the trench walls• Unexpected or transient loads adjacent to the

excavation• Vibration and water

Locating Underground Utilities

• Review your utility locate record information that you have with you on the job site, with other members of your crew.

• Use an electronic line locator to help determine the location of utilities affected by your proposed work.

• Electronic line locators detect the centre of the pipe. When measuring subtract the radius of the pipe from your measurement and this will be the top of the pipe.

Locating Underground Utilities

• If necessary a probe of at least 12mm in diameter and having a blunt end may be used to locate some buried facilities. Pointed probes must not be used to locate gas or electric facilities.

• The person operating the locator must advise those involved of the quality of locate and the degree of confidence that what has been located must correspond with the drawings, property pins and existing plant.

Locating Underground Utilities

• If the locator is getting interference, wandering signals, and or no correlation between peak and null , then steps must be taken to improve the locate.

• Such as improving the ground, try different frequencies, use both direct and conductive methods. If possible hook up the equipment at a different location.

• If the locator is not confident of the results obtained, then hand dig to expose the facilities.

Pipeline Rupture – Ontario - 2009 10 miles

Pipeline Rupture – Ontario - 2009

Methods of Exposing Pipe

• When exposing pipe, use the electronic line locator often to check the position and the depth of the pipe. Do repeat checks of the location after the pipe has been exposed.

• You must expose the location of the pipe in sufficient quantities to ensure you know exactly where the running line of the pipe is.

Methods of Exposing Pipe

• Hand dig to expose buried facilities using a shovel.

• Dig at an angle to the pipe, not directly over the pipe.

• When digging in hard dirt, use a prying rather than a striking motion.

Methods of Exposing Pipe

• Shovels can damage or cut through plastic gas lines. So be careful and don’t use your entire body weight when digging.

• Shovels can damage the coating on the steel gas pipe.

• Damage can also occur on the tracer wire which is attached to the plastic Gas mains and services. In the event of any damage to the tracer wire or to the pipe coating, please let us know about it and will repair any damages at no charge.

Mechanically Digging

• Don’t use a larger bucket than you need to do the job.

• If you don’t need teeth don’t use a bucket with teeth.

• A smooth bucket edge will have a chance of avoiding a total breach where a bucket with teeth usually will not.

• In tight corridors use the smallest bucket you can. There is often very little room in the right of ways now and a smaller bucket will help you avoid another utility.

Mechanically Dig and Hand Slump

• Mechanically dig beside the pipe, never closer than 1 meter plus the diameter of the pipe.

• Hand dig, slumping material into the mechanical dig zone.

• The excavator must not be used to dig within .5 m of the circumference of the pipe.

• When digging look for changes in the coating and wrapping indicative of previous work and perhaps fittings.

Mechanically Dig and Hand Slump

• Gas systems are constantly being worked on and changed. Often during work it is necessary to leave fittings and short pieces of pipe called stubs.

• These fittings and stubs are particularly vulnerable to getting snagged or pulled if machines are allowed to dig too close to gas lines. They are generally located on top but sometimes protrude out the side for a short distance.

Mechanical Digging

• You may use the mechanized equipment to break the ground cover over a gas main or service.

• You should at all times if possible dig parallel to the gas pipe. This will in itself reduce the risk of damage to the gas system.

• You may hand dig a trench over top and mechanically remove material in lifts.

Mechanical Digging

• This will require digging the hand dug trench over the top of the pipe the full length of the lift.

• If digging across the top of the pipe, the trench must be at least as long as the bucket is wide.

• If digging parallel on top then the hand dug trench must be at least as long as the full curl of the bucket removing the lift.

• Mechanically remove only half the depth of the hand dug trench.

Mechanical Digging

• Repeat this procedure until the pipe has been hand located for the full length required by your excavation.

• As a job progresses you may need to enlarge your excavation. This could be days later. This could be due to slumping material caused by water or vibration. Remember to remove this material with the same care and vigilance and methods of locating as if digging into new ground.

Mechanical Digging

• If hand exposing is not practical due to hardpan, frost, foreign utility congestion, or other causes, consider using hydro-vac equipment.

• To prevent damage to the pipe coating it is important to keep the pressure wand moving and that there is a soft cone on the end of the vacuum tube.

Mechanical Digging

• Frost conditions are often highly variable over short distances.

• If possible consider moving the excavation to an area with less frost. Hydrovac equipment is often successful in frozen ground.

• Also consider the use of ground thawing equipment.

Backfilling

• If possible backfill in dry conditions, and prevent surface water from flowing into the excavation.

• Place the backfill in a manner that does not disturb and or damage the pipelines or coating.

• Don’t backfill against new concrete or masonry before it has properly cured. (at least 80% of it’s designed strength).

• Your compaction typically is done in layers between 18” and 3ft.

• Backfilling and compaction procedures will be specific according to the type of pipeline you are dealing with, the type of soil and equipment you have available.

• Compaction

Pipeline Rupture – Ontario - 2009

Midwest USA - 2008

Questions??

April 18, 2023

Terasen Inc. A Fortis company.

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