Exposing Facilities

Safe Digging: Digging inside the Tolerance Zone - Potholing


Safely exposing an underground facility is the best way to work within the tolerance zone. That way you know precisely where the underground facility is located, making it easier to avoid.

Before you can use mechanized digging equipment in a tolerance zone, you must verify the presence and location of the buried facility. There are many non-destructive methods to expose underground facilities including hand digging, vacuum excavation, pot holing and soft digging. If you must remove pavement or masonry, equipment can be used, but only to the depth of that pavement or masonry.

If you are unable to locate the facility after performing a reasonable search, contact the facility owner directly for help. Once the facility is located, mechanized digging equipment can be used.

If you will be exposing a facility during your excavation, you are required to provide adequate support and protection for it. An unsupported portion of a line can pull and distort a joint or splice that is out of sight. The damage can occur several feet up the line - underground - and you'd never see it.In addition, you are required to provide an adequate backfill upon completion. 

Safe Digging: Depth


Flags and painted lines on the ground tell you the horizontal direction the facility is running. They do not tell you its depth. If you are going to cross or work near an existing facility, you may want to first verify its depth by hand digging.

Yes, there are standards for installing underground facilities at a certain depth. But that depth can change over years.

In the example above, the power line was buried at a depth of three feet. Later, the area was developed and landscaped. At the berm the line is now five feet underground, but at the swale it is only one foot below the surface. Accidentally discovering this situation could literally be a heart stopping experience.

The best way to know how deep the line is buried it to expose it using the safe digging methods mentioned in another module.