4.2 Line Locating & One-Call (CGA) Coordination

Line Locating & One-Call (CGA) Coordination

Quick Answer: Before any mechanical excavation, the contractor must contact the one-call notification center (811 in the U.S.) so existing underground utilities can be marked. The API 1169 inspector verifies that an active one-call ticket is on file, that markings are present and current, that the crew white-lines the excavation area, waits the required time, respects the marks, and hand-exposes existing utility crossings before trenching. The Common Ground Alliance (CGA) Best Practices, current edition, is a testable reference in its entirety.

The One-Call System

The one-call system is the process by which an excavator notifies underground facility operators before digging, so those operators can mark their facilities at the excavation site. In the United States, calling 811 routes the request to the appropriate state one-call notification center, which then notifies member utility operators. Each operator sends a locator to mark its facilities, typically within two to three business days, depending on state law.

Inspector checkpoint: Before excavation begins at any station, the inspector confirms that a one-call ticket has been placed for that area, that the ticket is still active (not expired), and that the markings are present and current. An expired ticket or missing markings is a stop-work condition.

CGA Best Practices — a Testable Reference

The Common Ground Alliance (CGA) Best Practices, current edition, is a testable reference for the API 1169 exam. The entire document is in scope — not just a summary. The Best Practices are organized into chapters covering planning, notification, locating, marking, excavation, and backfilling. The four-step excavation safety process below is the core the inspector applies in the field.

The Four-Step Excavation Safety Process

White-Lining

White-lining is the practice of marking the boundary of the proposed excavation before the locator arrives. It is a CGA Best Practice and is the first thing the inspector should look for at a new excavation site.

• White paint, white flags, or white stakes outline the area
• The locator marks only within the white-lined boundary
• White-lining reduces over-marking (locating unnecessary areas) and under-marking (missing the actual dig area)
• If the crew moves the excavation, a new white-line and a new or updated ticket are required

The Tolerance Zone and Hand-Digging

The tolerance zone is the area on each side of a marked underground facility within which mechanical excavation is prohibited until the facility is exposed. The width is set by state law or project specification — commonly 24 inches on either side of the marked line, but the inspector must verify the applicable state requirement.

Within the tolerance zone, the crew must use:

• Hand digging (shovels)
• Vacuum excavation (hydro or air)
• Other non-invasive methods approved by the project

Inspector checkpoint: Mechanical excavation equipment (backhoes, trackhoes, trenchers) must not operate within the tolerance zone until the existing utility is hand-exposed and verified.

Exposing and Verifying Existing Utility Crossings

At every location where the new pipeline crosses an existing underground utility, the existing utility must be exposed and verified before the trench is excavated through it. This is a critical inspector verification point.

Exposure Procedure

1. One-call ticket placed for the crossing area.
2. Utility marked by the facility owner.
3. Hand-dig or vacuum-excavate to expose the utility at the crossing.
4. Verify the utility — confirm it is where it was marked, measure depth and clearance, record the crossing station.
5. Trench through only after the utility is exposed, supported, and clearance is confirmed.

If the utility is not where marked (a "locate deviation"), the inspector documents the deviation and the one-call center and facility owner are notified before proceeding.

Maintaining an Active Ticket

One-call tickets have a defined validity period (state-specific, commonly 10–30 days, plus a marking-valid period). The inspector verifies:

• The ticket number is recorded in the daily report
• The ticket has not expired
• Marks are still visible and current
• If marks are destroyed or the ticket expires, a renotify or new ticket is placed before excavation resumes

Note: Excavating on an expired ticket, or with destroyed marks, is treated the same as excavating with no ticket at all.

Inspector Daily Documentation (One-Call)

The inspector's daily report captures, at minimum:

• One-call ticket number(s) and expiration date
• Utility operators notified
• Date and time markings were verified present
• Stations where existing utilities were exposed
• Any locate deviations and disposition
• Any excavation that began before marks were complete (nonconformance)

Key Takeaways

• One-call (811) notification is required before any mechanical excavation; the inspector verifies the ticket is active and marks are present and current.
• The CGA Best Practices, current edition, is a testable reference in its entirety.
• The four-step process — white-line, wait, respect the marks, dig with care — is the field standard.
• Existing utilities must be hand-exposed and verified at every crossing before trenching through them.
• An expired ticket or destroyed marks trigger a stop-work and renotify.