Leak Recognition and Response

Detecting a Pipeline Leak

Although a pipeline leak is rare, it is important to know how to recognize the signs. If a pipeline were leaking, you may be able to smell, see and/or hear it.

Natural Gas

What you may smell:

  • Natural gas is said to be odourless but some people detect a hydrocarbon smell. If the gas is odourized it may smell similar to rotten eggs.

What you may see:

  • Dead or dying vegetation on or near a pipeline in a normally green area.
  • Water bubbling or blowing into the air at a creek, pond or river.
  • Dirt being blown or appearing thrown into the air.
  • Frost build-up on the ground.
  • Fire coming from the ground or appearing to burn above ground.

What you may hear:

  • A roaring, blowing, hissing, or loud whistling sound.


What you may smell:

  • Many petroleum products have a distinct smell. Crude oil can possess a rotten egg, gasoline, tar or “skunk-like” odour.

What you may see:

  • Amber to black liquid.
  • Rainbow sheen or black liquid on top of water.
  • Discoloured vegetation on or near a pipeline in an area that is usually green.
  • Stained or melted snow/ice over pipeline areas.

What you may hear:

  • A hissing or roaring sound – oil travels through the pipeline under pressure. If even a small leak were to occur, there would be an audible hissing, roaring or rushing water sound as pressure is released.

If you think you’ve struck a pipeline or suspect a pipeline leak:


  1. Stop all work. Shut off machinery and leave the area on foot.
  2. Don’t attempt to repair the pipe or operate any valves.
  3. Call ‘911’ or your local emergency services number from a safe location.
  4. Call TransCanada’s emergency number
    1.888.982.7222 (Canada)
    1.800.447.8066 (US)
    1.800.830.9865 (PNGTS)
    01.800.111.3333 (Mexico)
  5. Don’t continue your project until authorized to do so by a TransCanada representative.


Related Information


Click Befoe You Dig

United States:



All States: 01-800-111-3333

Emergency Numbers

Canada: 1-888-982-7222

U.S.: 1-800-447-8066
Portland Natural Gas Transmission System (PNGTS): 1-800-830-9865
Columbia Gas Transmission, Crossroads Pipeline, Hardy Storage Company & Millennium Pipeline: 1-800-835-7191
Columbia Gulf Transmission: 1-866-485-3427
Columbia Midstream: 1-855-511-4942

Mexico: 01-800-111-3333

Pipeline Safety Fact Sheet

Material Safety Data Sheet (MSDS) Information

Additional Resources