Heh weird
As the Alberta 1 Call web-guy, I'll tell you, that ANY (1 foot or even less) ground disturbance should be called in.
U/G utility lines migrate due to tectonic shifts, rain, groundswell, heat, cold, road grading, vegetation, etc etc etc and a gasline originally buried 3 feet deep can move to less than 6 inches below the surface.
As well, the frost line in Calgary is ~5-6 feet down, and most decking piles only go 3-4 feet.
Remember! Alberta 1 Call requires a
minimum 2 full working days notice to complete a locate, and after 12 PM there is a one day carry over, so call early, and call in the morning!
(or contact me directly, and put it in online at
www.alberta1call.com , it's free!)