The presence and type of underground facilities are indicated by permanent aboveground and belowground markers and material.63
A combination of aboveground and belowground markers is used to identify and locate underground facilities. The facility is color-coded in accordance with the American Public Works Association (APWA) guidelines to assist in identifying an aboveground or belowground facility.
The purpose of aboveground markers is to identify underground facilities, not to locate for excavation or circumvent the one call process. However, designing underground facilities for future location reduces the risk of an incorrectly marked underground facility during an excavation project. Aboveground markers are developed during the design process and include the company name, type of facility, emergency contact, and the one call number. The locations and types of markers are specified in the construction plans. The design provides a marker system that includes, but is not limited to, stream crossings, public road crossings, other facilities’ rights-of-way, railroad crossings, heavy construction areas, and any other location where it is necessary to identify the underground facility location. If nondetectable facilities are being installed, the design includes a means to accurately locate the underground facility from the surface. Road decals, stencils, tracer tapes, electronic markers, or other appropriate systems may mark areas where traditional markers are considered impractical.
The purpose of belowground markers is to identify underground facilities. Belowground markers are used in conjunction with aboveground markers. Belowground markers may include tracer wire, warning tape, and/or electronic marking devices. More than one type of belowground marker may be used. Installation of belowground markers should comply with AGA, ANSI, or other industry standards or governing regulations including, but not limited to, using a coated corrosion-resistant wire, installing cathodic protection, proper grounding, marking the end placement or approximate location of belowground markers with aboveground markers, protecting belowground markers from damage during backfill operations, and placement/method of installation.
Provisions to aid in future locating requests are included in the design. In addition, an effective marker system is beneficial to the underground facility owner/operator and first responders to an area involving more than one underground facility or an incident near underground facilities.