Utility field marking is how buried pipes and cables get identified on the ground before you dig, and you start it by contacting the 811 one-call system. A locator crew comes out during a short waiting period, paints or flags the lines in standard colors, and you dig around those marks with the care each color requires. Federal law under 49 U.S.C. § 60114 requires anyone planning to excavate to notify the appropriate one-call system first, and that obligation covers homeowners, contractors, and government crews alike.1Office of the Law Revision Counsel. 49 USC 60114 – One-Call Notification Systems There is no size exemption. Installing a mailbox, planting a tree, setting a fence post, or building a deck all trigger the requirement, because utility lines can sit only inches down and even shallow hand digging in the wrong spot can sever fiber or nick a gas line.
How to Request a Locate
Call 811 or file a ticket through your state’s online notification portal. Have the exact street address ready, the nearest cross street, a description of the work, and the specific area where you plan to dig. Outlining that dig area in white paint or flags before the crew arrives helps them focus on the right zone rather than scanning your whole property. White is a color in the code specifically for the excavator to use.
After you submit, you get a ticket number and a list of every utility operator that will be notified. Federal law sets a minimum waiting period of two working days before you can break ground, not counting the day you filed.1Office of the Law Revision Counsel. 49 USC 60114 – One-Call Notification Systems Some states use two business days, others three. Weekends and legal holidays generally do not count.
Many states run a Positive Response system that requires each notified operator to report the status of your ticket back through an online portal or by email. Check it before you dig. If an operator has not responded, they may not have located their lines yet, and starting work anyway is where things go wrong. Verify wrong details on the ticket, too: if you gave the wrong address or a bad dig-area description, the marks land in the wrong place and you can be held liable for the resulting damage.
What the Colors Mean
Once utilities are marked, the paint and flags follow the American Public Works Association uniform color code so anyone on site can read them at a glance.2American Public Works Association. Uniform Color Code
- Red: Electric power lines, cables, conduit, and lighting cables.
- Yellow: Gas, oil, steam, and petroleum lines. These demand the most cautious excavation because a rupture can cause an explosion or toxic release.
- Orange: Communication, alarm, and signal lines, including telephone, fiber optic, and cable television.
- Blue: Potable water.
- Green: Sewers and drain lines.
- Purple: Reclaimed water, irrigation, and slurry lines.3American Public Works Association. APWA Guide – Uniform Temporary Marking of Underground Facilities
- Pink: Temporary survey markings.
- White: The proposed excavation area, placed by the person requesting the locate.
How Close You Can Dig to a Marked Line
The painted line marks the approximate centerline of the utility, not the pipe’s edge. Every state defines a tolerance zone extending outward from that mark, typically 18 to 24 inches on each side, where you cannot use a backhoe or other heavy mechanical equipment.
OSHA requires that when excavation approaches the estimated location of an underground installation, the exact location be determined by “safe and acceptable means.”4Occupational Safety and Health Administration. Specific Excavation Requirements – 1926.651 OSHA has clarified that traditional hand-digging with a shovel can still damage certain utilities, particularly electrical lines, and may not qualify as acceptable in every case.5Occupational Safety and Health Administration. Acceptable Methods to Locate Underground Utility Installations
The Common Ground Alliance recommends vacuum excavation (pressurized water or air with suction), pneumatic hand tools, and pot holing to expose the utility before full excavation begins.6Common Ground Alliance. Excavation Within Tolerance Zone Vacuum excavation is the industry standard near gas and electric lines, where a shovel blade can cause real damage. The principle is the same in every case: visually confirm the utility before bringing heavy equipment near it.
What 811 Does Not Cover
The free 811 service covers only the infrastructure a utility company owns and maintains, generally running from the main line to your service meter or connection point. Everything past that point on your property is yours to locate. This is where homeowners get caught out.
Wire you ran to a detached garage, a propane line to a pool heater, an irrigation system, low-voltage landscape lighting: none of that shows up on an 811 ticket. Public locators have no records for those lines and no obligation to find them. Hit one and the repair bill is yours.
Private locating firms fill the gap using the same electromagnetic and ground-penetrating radar equipment. For a standard residential lot with typical metallic utilities, expect roughly $150 to $400. Properties with non-metallic lines that need GPR scanning run higher, often $400 to $800 or more depending on size and complexity. Non-metallic pipe (PVC, plastic gas line, concrete conduit) is essentially invisible to standard electromagnetic locators; some installations include a tracer wire so the line can be detected later, and where none exists, GPR is the fallback with real limitations in wet or clay-heavy soils.7Federal Highway Administration. Underground Utilities – Ground-Penetrating Radar (GPR) – Plastic/PVC
If You Hired a Contractor
Legally the person doing the excavation makes the 811 call, so a contractor digging your pool should be filing the ticket. Verifying it happened is still in your interest, because the mess lands on your property either way. Ask for the ticket number before work begins.
When Marks Expire
Locate marks are not permanent. State ticket validity periods typically run 10 to 21 calendar days. Once the ticket lapses, the marks are considered unreliable and you have to submit a renewal and wait for utilities to re-mark before resuming.
Weather and traffic can degrade marks faster than that. Rain washes paint. Equipment flattens flags. If markings become unreadable at any point during your project, you are responsible for getting them refreshed. Digging on marks you can barely see is treated the same as digging with none.
If You Strike a Line
Even with proper marking, strikes happen, and the first few minutes matter.
Gas line. Get everyone away from the area and move upwind. Shut off equipment and eliminate ignition sources, including cell phones near the leak. Call 911. Do not try to close valves or stop the leak yourself. Warn people in nearby buildings, because gas can travel through underground drains into structures you would not expect.
Electric line. Drop any equipment that contacted the line and move away without touching metal components. Soil around a severed energized cable can deliver a fatal shock, and the danger zone is not obvious from the surface.
Water or sewer line. Immediate risk is lower, but you still must report the damage to the utility operator. Federal law requires anyone who damages a pipeline facility in a way that could endanger life or cause serious harm to promptly report it.1Office of the Law Revision Counsel. 49 USC 60114 – One-Call Notification Systems Report every contact, not just visible breaks. A minor scrape on a gas line coating can lead to corrosion and delayed failure.
Penalties for Digging Without a Ticket
Every state has a damage prevention law with penalties for excavating without a valid locate ticket. State fines range from a few hundred dollars for a first offense to six figures for repeat violations or incidents causing serious damage. At the federal level, PHMSA can impose penalties for pipeline damage under 49 U.S.C. § 60122, and the amounts climb significantly for major incidents.
Money is only part of the exposure. With a valid ticket, you can argue you followed proper procedure and the line was either mismarked or unlocatable. Without one, you are presumptively negligent in most jurisdictions, which changes who pays for the repair, the service interruption, any environmental cleanup, and any injuries. Insurance carriers may deny coverage for damage caused by an excavator who skipped legally required notification, and criminal charges are possible in some states if someone is injured or killed. The Common Ground Alliance’s 2024 DIRT Report found that no-notification excavation was the single most common root cause of utility damages nationally, accounting for nearly 25% of reported incidents.8Common Ground Alliance. 2024 DIRT Report The 811 call takes a few minutes and is the cheapest step in the entire project.