Safe Digging Practice
To safely excavate a pipeline, excavators must always follow the most recent copy of the Guidelines for Excavation in the Vicinity of Utility Lines that is jointly published by the Electrical Safety Authority (ESA) and Technical Standards and Safety Authority (TSSA).
Damage to pipes or a utility line due to unsafe digging practices can create a safety hazard or even disrupt utility service to an entire neighbourhood when the system must be shut down to enable repairs to be carried out.
Under Ontario regulations, it's against the law to dig without first having the natural gas lines located. Prior to excavation, verify that the limits of the natural gas line locate markings correspond with the limits of the proposed excavation area and visually inspect the located area for unmarked facilities. If, based on this inspection, you believe the gas line locate is incomplete, inaccurate, or any other discrepancies are found, contact the locator directly or contact Ontario One Call at 1-800-400-2255.
Do not use mechanical excavation within the boundary limits of the natural gas line locate without first hand digging to expose the pipeline to determine the exact centre line and depth of cover of the pipeline. Once the pipeline has been positively located, continue hand digging at regular intervals to ensure the mechanical excavation maintains a minimum of 300 mm clearance from the pipeline. Do not perform any mechanical excavation closer than 300 mm to the pipeline.
If a gas line is found during excavation within the located area that is not identified on the locate form, do not assume it is an abandoned gas line. First call Union Gas Emergency at 1-877-969-0999. The unknown facility could be:
- An abandoned gas line
- A newly installed gas line
- Unmarked live gas line
- Other non-gas facility
Note: Never assume the depth of a buried gas pipeline as elevations can change (e.g. they may be purposefully offset to go under another utility). Furthermore, fittings are installed on a pipeline which may protrude above the elevation of the pipeline.
Backfilling Around Pipelines
Backfilling an exposed pipeline is an important procedure for two reasons:
- To prevent immediate damage
- To prevent future damage
Compact backfill sufficiently to eliminate any settlement of the pipe or ground surface.
Union Gas permits any compacting device that will not:
- Cause any deformation or damage to the pipe or coating, or
- Cause any damage to any adjacent building, structure or utility.
Note: Mechanical tampers are generally used to backfill a pipeline and they are hand-held devices.
Backfill shall be over and around the pipeline and must be done with shading material. The shading shall be acceptable material that will not damage the pipe or coating. This includes the following:
- Native Clay
- Fines and Screenings
Materials that are not acceptable for shading include:
- Granular "A"
- Granular "B"
- Frozen native soil
- Big and/or sharp stones or rocks
- River rock