What is a cross bore?
A cross bore, also called a blocked sewer line, is caused when a natural gas line is accidentally drilled through a sewer line during installation. A cross bore can potentially cause a back up in your pipe which will need to be cleared.
In Alberta, there have been cross bores discovered in sewer lines and can go undetected for years or decades.
What you need to know:
There's no threat unless mechanical cleaning equipment (i.e. motorized auger, power-snake or other root-cutting equipment) is used to clear a blocked sewer line.
This equipment can severely damage a gas line causing gas to leak into the sanitary or storm systems and then into buildings.
What this means to you:
Be aware natural gas lines installed using trenchless methods, such as horizontal directional drilling, could have inadvertently penetrated service lines.
Before using mechanical cleaning equipment, always conduct a video inspection of the sewer line. This is necessary if the blockage is beyond the outside wall of a building.