Image credit: WorkSafeBC Hazard Alert – WS 2014-04

Chances are, you’ve heard how important it is to “call before you dig” – but it’s just as important to “call before you clear” when working with sewer lines.

The reason for this is to avoid a cross bore – which occurs when a natural gas line was installed unintentionally through a sewer service line.

“Calling FortisBC before beginning any clearing work on a sewer outside of the building foundation is extremely important,” says Ian Turnbull, Damage Prevention & Energy Service Manager with FortisBC. “In the rare instance a cross bore exists, clearing a blocked sewer could damage the pipeline and allow natural gas to travel through the sewer system. This poses a public safety risk.”

The FortisBC website explains that “…these intersecting lines can go undetected and co-exist safely until the clearing of a blocked sewer damages the pipeline. If damaged, natural gas can travel through the sewer system and into homes and businesses, risking public safety and potentially costing money for repairs.”

FortisBC asks you to:

* Call or ask your sewer clearing professional to call BC One Call at 1-800-474-6886. The service is free, easy and available 24 hours a day.
* Let the agent know that you’re calling about a “sewer service line blockage.”
* BC One Call will notify FortisBC immediately and we will make every effort to respond within two hours or less.

You can also call FortisBC’s natural gas emergency line (24 hours) at 1-800-663-9911.

Cross bores also pose a risk to workers doing horizontal directional drilling to install underground utilities.

“This installation method is useful because it minimizes disruption to the surface and traffic,” reads this WorkSafe bulletin: The dangers of cross bores when directional drilling.

For more information, read this WorkSafeBC hazard alert: The danger of explosions when clearing sanitary or storm sewers.

Thanks to FortisBC for answering my questions about this.