Locators mark buried facilities with paint, flags and stakes in the APWA color code (APWA uniform color code). Excavators white-line where they plan to dig. Every crew member should be able to read a marked site at a glance.
The Colors
| Color | Marks | On the FAHMY Map |
|---|---|---|
| Orange | Communication, alarm or signal lines, cables or conduit | Your own plant and foreign plant |
| Red | Electric power lines, cables, conduit and lighting cables | Underground Electric |
| Yellow | Gas, oil, steam, petroleum or gaseous materials | Gas Main |
| Blue | Potable water | Water Main |
| Green | Sewers and drain lines | Sewer Lateral |
| Purple | Reclaimed water, irrigation and slurry lines | Not drawn |
| Pink | Temporary survey markings | Not drawn |
| White | Proposed excavation | White-Lining |
APWA bases the colors on the ANSI Z535.1 safety colors. Paint shades on the screen are approximations; the color name is what counts.
Why Orange?
Orange marks communication lines, so it is the color of what OSP crews build.
How to Read a Marked Site
- Marks show approximate horizontal location only. They do not show depth. Never assume depth from a mark or a print (state one-call law; CGA Best Practices).
- Marks name the owner. The APWA guideline has marks and markers show the name, initials or logo of the facility owner, and the facility width when it is wider than 2 in (50 mm).
- Look for offset marks. Where the surface over a line will be removed, the locator may place offset marks that say the facility is a stated distance away.
- Joint trench lines are marked side by side in their own colors.
- White marks are yours. White paint, flags or stakes mark the proposed excavation, such as white dashes down the centerline of a bore path, so locators mark only what matters. On roadways, the APWA guideline keeps white surface marks within 1.5 in by 18 in (40 mm by 450 mm).
Tolerance Zone
The tolerance zone is the band either side of the marked facility, measured from each outside edge of the facility, where you dig only with the methods your state law allows, typically non-powered hand tools or a non-invasive method such as vacuum excavation, until the facility is exposed.
Before You Dig
- Submit a locate ticket through
811, at least the notice period your state requires (varies by state). - Wait for the legal start time and confirm every member utility has responded, through the positive response system where your state has one.
- Compare the marks with the ticket. Request re-marks for anything missing, faded or in conflict.
- Arrange a private locate for lines one-call members do not mark, such as sewer laterals and private electric.
The full procedure is in one-call locates and ticket management and potholing. Consensus practice is in the CGA Best Practices.
On the Map
- Locate Marks: APWA paint and flags on the surface.
- White-Lining: white dashes down the centerline of the proposed bore.
- Tolerance Zone: the hand-dig band either side of the marked facility, measured from its outside edges.