Color-coded surface marks (paint or a similar coating) should be used to indicate the locations and route of buried lines. To increase visibility, color-coded vertical markers (temporary stakes or flags) should supplement surface marks.
All marks and markers should indicate the name, initials or logo of the company that owns or operates the line and the width of the facility if it is greater than 50 mm (2").
If the surface over the buried line is to be removed, supplemental offset markings may be used. Offset markings should be on a uniform alignment and must clearly indicate that the actual facility is a specific distance away.
The American Public Works Association encourages public agencies, utilities, contractors, associations, manufacturers and all others involved in excavation to adopt the ULCC Uniform Color Code using the ANSI standard Z53.1 Safety Colors shown at right.
Any excavation within the tolerance zone should be performed with hand tools until the marked facility is exposed. Please see the following illustrations.
The width of the tolerance zone may be specified in law or code. If not, 0.5 m (18") is recommended from each side of the facility. The tolerance zone includes the width of the facility and 0.5 m (18") measured horizontally from each side of the facility.
Use white marks to show the location or boundary of a proposed excavation. Surface marks on roadways should not exceed 40 mm by 500 mm (1 ½" by 18"). The facility color may be added to white flags or stakes.