What's underneath your feet: Cross bores
If you experience a sewer back up, be sure you or your plumber always contacts EPCOR before attempting to clear the line with any mechanical equipment
A network of power, natural gas, phone and cable lines, as well as water and sewer pipes may lie just under the surface of your property. In rare instances, a gas line is mistakenly installed within a sewer line, which is known as a cross bore.
If a cross bore is struck while a sewer backup is being cleared, it could cause natural gas to leak into your property or the sewer system, potentially leading to personal injury or an explosion.
In the United States, there have been cases of home explosions, fire, injury and death due to natural gas leaks from cross bores. While no instances have taken place in Canada, there have been cross bores detected in Ontario.
How cross bores occur
Trenchless or horizontal directional digging techniques are commonly used to install natural gas pipelines underground. These techniques have many benefits compared to open trench digging including being more cost effective, less disruptive than digging through streets and landscaping and having fewer environmental impacts. However, these methods don't enable construction crews to visually confirm where the new line has been placed, which may result in the line being installed within an older sewer line that is made of material that cannot be detected by utility locating technology.
Cross bores are not often the cause of a sewer backup but they can allow tree roots and other obstructions to penetrate sewer lines, which can lead to blockages.
Keep your property safe
Cross bores pose no safety threat unless they are struck by motorized or high pressure equipment, typically used by drain cleaning professionals to unclog a plugged sewer. This includes motorized augers, power-snakes or other root-cutting equipment.