What Are Underground Utilities?
The term “utility” refers to the services provided by public utility companies, including electricity, natural gas, water, sewage, phone lines, and more.
“Underground utilities” refers to the vast infrastructure of pipes and cables that transport water, gas, and electricity to each building in a community. There are more than 100 billion feet of underground utilities in the U.S., which means there’s over a football field’s length of line per person.
Whenever a property owner plans to dig underground, it’s imperative to locate the underground utilities on the site before digging. The process of identifying and labeling underground public utility mains is known as “utility location.” While private lines are considered the responsibility of the landowner (this may include gas lines, private sewer laterals, sprinkler systems, and certain electric lines), underground utilities are the responsibility of the public utility company and homeowner. They will be able to mark the location of the lines for you, but you or your contractor must call them first.
Color Code for Marking Underground Utility Lines
In the United States, the American Public Works Association (APWA) provides Uniform Color Codes for the temporary marking of underground utilities. These color codes are applied using paint, chalk, stakes and/or flags to indicate the location and route of different underground utilities. Having this standard, uniform color code helps everyone (contractors, excavators, utility companies, municipalities or “any others working on or near underground facilities”) avoid accidents and unneeded damage.
It’s up to the owners of the public lines to mark the locations near a job site according to this standard:
Once your lines have been marked, they are usually only valid for a certain number of days (28 is common). This is due to natural wear and tear that will harm visibility, as well as the fact that erosion and root growth have been known to alter the depth and location of buried lines over time. Be sure to plan digs according to the requirements of your state.
The Dangers of Replacing Underground Utilities
According to the Common Ground Alliance, an underground utility line is damaged once every 6 minutes nationwide because someone decided to dig without knowing the location of their lines. While these mistakes are often caused by large excavation projects, a simple mailbox installation or even a small gardening project can lead to striking utility lines you didn’t realize were there.
Guidelines For Operator’s Facility Field Delineation
Operator markings of facilities include; the appropriate color for their facility type; their company identifier (name, initials, or abbreviation) when other companies are using the same color, the number and width of their facilities and a description of the facility (HP, FO, STL, etc). Use paint, flags, stakes, whiskers or a combination to identify the operator's facility(s) at or near an excavation site.
Marks in the appropriate color are to be approximately 12" to 18" in length and 1" inch in width and separated by approximately 4' to 50' in distance as an example. When marking facilities the operator is to consider the type of facility being located, the terrain of the land, the type of excavation being done and the method to adequately mark its facilities for the excavator.
The following marking illustrations are examples of how an operator may choose to mark their subsurface installations.
Single Facility Marking: Used to mark a single facility, marks are placed over the approximate center of the facility (Figure 1) or over the approximate outside edges with a line connecting the two horizontal lines (in the form of an H) (Figure 2). These examples indicate an operator’s 12” facility. When a facility can be located or toned separately from other facilities of the same type it is marked as a single facility.
Multiple Facility Marking: Used to mark multiple facilities of the same type (e.g. electric), where the separation does not allow for a separate tone for each facility but the number and width of the facilities are known. Marks are placed over the approximate center of the facilities and indicate the number and width of the facilities.
Conduit Marking: Used for any locatable facility being carried inside conduits or ducts. The marks indicating the outer extremities denote the actual located edges of the facilities being represented. An example would be 4 plastic conduits that are 4" in diameter (4/4" PLA), and the marks are 16" apart indicating the actual left and right edges of the facilities.
Corridor Marking: Used to mark multiple facilities of the same type (e.g. electric), in the same trench where the total number of facilities is not readily known (operator has no record on file for the number facilities) and that are bundled or intertwined. Marks are placed over the approximate center of the facilities and indicate the width of the corridor. The width of the corridor is the distance between the actual located outside edges of the combined facilities. This example indicates a 12" corridor (12" CDR).
Changes in direction and lateral connections are to be clearly indicated at the point where the change in direction or connection occurs with an arrow indicating the path of the facility. A radius is indicated with marks describing the arc. When providing offset markings, (paint or stakes), show the direction of the facility and distance to the facility from the markings.
An operator's identifier (name, abbreviation or initials) is to be placed at the beginning and at the end of the proposed work. In addition to the previous, subsequent operators using the same color will mark their company identifier at all points where their facility crosses another operator's facility using the same color. The maximum separation of identifiers is to be reduced to a length that can be reasonably seen by the excavator when the terrain at the excavation site warrants it.
When there is "No Conflict" with the excavation complete one or more of the following:
Operators of a single type of facility (e.g. TELECO) would mark the area "NO" followed by the appropriate company identifier in the matching APWA color code for that facility (e.g. "NO TELECO")
Operators of multiple facilities would mark the area "NO" followed by the appropriate company identifier in the matching APWA color code for that facility with a slash and the abbreviation for the type of facility that there is "No Conflict" (e.g. "NO GASCO/G/D"). The example illustrates that GASCO has no gas distribution facilities at this excavation site. The abbreviation for gas transmission facilities is "/G/T", electric distribution is "/E/D" and electric transmission is "/E/T" these should be used when appropriate.
Place a clear plastic (translucent) flag that states "No Conflict" in lettering matching the APWA color code of the facility that is not in conflict. Include on the flag the operator's identifier, phone number, a place to write the locate ticket number and date. Operators of multiple facilities would indicate on the flag, which facilities were in "No Conflict" with the excavation as in the previous example.
If it can be determined through maps or records that the proposed excavation is obviously not in conflict with their facility (s) the locator or operator of the facility may notify the excavator of "No Conflict" by phone, fax, or email, or through the One Call Center, where electronic positive response is used. Operators of multiple facilities would indicate a "No Conflict" for each facility as in the previous examples.
Place "No Conflict" markings or flags in a location that can be observed by the excavator and/or advise the excavator by phone, fax, or email that there is "No Conflict" with your facilities. When the excavation is delineated by the use of white markings, place "No Conflict" markings or flags in or as near as practicable to the delineated area.
"No Conflict" indicates; that the operator providing the "No Conflict" has no facilities within the scope of the delineation, or when there is no delineation, there are no facilities within the work area as described on the DigAlert.