The Utah state law explains it this way:

54-8a-7. Notice of damage — Repairs. (

(1) If an excavator contacts or damages an underground facility, the excavator shall:

(a) immediately notify the appropriate operator and then proceed in a manner that is reasonably calculated to avoid further damage to the underground facility; and

(b) immediately call 911 if the excavation may result in an immediate risk to human life.

(2) Upon receipt of notice, the operator shall immediately examine the underground facility, and, if necessary, make repairs.