It is the responsibility of the utility/facility owner to ensure their buried lines are marked. ORC 3781.29(A)(1) states :

“…within at least two working days, not including the day of the notification, of receiving notice under section 3781.28 of the Revised Code, each utility shall review the status of its facilities within the excavation site, locate and mark its underground utility facilities at the excavation site in such a manner as to indicate their course, and report the appropriate information to the protection service for its positive response system…”

Some utilities also use a contract locating service to mark their lines on their behalf.