Underground Utility Locate Before Excavation

Purpose

The one-call ticket is necessary and it is never sufficient. The public locate covers each member operator's own facilities, which generally stop at the meter or the point of demarcation, and almost every line a foundation pit actually hits sits on the customer's side of that point: gas to a detached shop or a pool heater, electric to a garage, irrigation mains, septic laterals, low-voltage lighting, a private well line. Those are not the utility's to mark and nobody marks them unless this shop arranges it.

That is the standing instruction here. Place the ticket, then treat the customer side as an entirely separate locate with its own scope, its own technology limits and its own written acknowledgment. If a line is struck at any point in this procedure, stop everything and go to step 8 before doing anything else.

Scope

Covers utility clearance for every excavation on foundation repair work: pier pits, wall access trenches, drain and downspout trenching, anchor deadman pits, and test pits opened during an assessment.

Does not cover the excavation itself, which the excavation and shoring SOP owns and which cannot start until this procedure closes. Does not cover interior slab penetration, where the hazard is post-tension tendons and in-slab conduit rather than buried utilities. Does not resolve who pays when an unmarked line is damaged, which is a legal question for the shop's own attorney and insurer, not something a procedure can settle.

Roles and responsibilities

Procedure

Step 1: Define the dig footprint and white-line it before you call

Mark the proposed excavation on the ground in white, which is the APWA color for proposed excavation, and mark it generously enough to include spoil, equipment tracks and the working room around each pit rather than just the hole. Acceptance: a white outline on the ground and a photograph of it in the job file before the call is placed. Wrong looks like describing the dig over the phone as "the back of the house", which produces marks in the wrong yard or a locator who walks a strip the pit falls outside of. Re-mark and re-describe rather than working an inaccurate ticket.

Step 2: Place the ticket and record its three dates

Call 811 or file online, describe the work and the marked area, and record the ticket number, the legal start date and time, and the expiry. Notification lead time is set by your state's one-call statute and is commonly two to three business days excluding the day of the call, and ticket life is commonly ten to twenty calendar days, also state-set, so read your own state's numbers rather than carrying another state's from a prior job. Acceptance: ticket number and all three dates in the job file. Wrong looks like a crew mobilizing on the day the ticket was placed. Nobody digs before the legal start time even if marks are already on the ground.

Step 3: Confirm a response from every member operator, not just the presence of paint

Check the positive response system where your state has one, and reconcile the list of notified operators against the responses. A response of no facilities in the area is a response; silence is not. Acceptance: every notified operator shows either marked or clear before the first shovel. Wrong looks like paint on the ground from three operators and nothing from the fourth, which usually means the fourth has not been out yet. Stop, call the center for a status or a re-notification, and do not reason from the paint you can see to the operator you cannot.

Step 4: Commission a private locate and put the gaps in writing

Ask the customer what they or a prior owner buried, then have a private locator sweep the footprint for customer-side lines with electromagnetic equipment and ground penetrating radar. Acceptance: a written private locate report naming what was found, what was swept and found nothing, and specifically where a trace could not be completed. Wrong looks like a report that shows only lines. Non-conductive pipe with no tracer wire, which covers most poly gas and much PVC water and irrigation, cannot be located electromagnetically at all, and ground penetrating radar loses depth badly in wet clay, which is the exact soil this trade works in. Where the locate is partial, get the customer's signed acknowledgment naming the unlocatable line before any machine work, and treat the whole suspected path as if a live line runs through it.

Step 5: Verify the marks on site and photograph them before they wash off

Walk the footprint and match paint and flags to the APWA Uniform Color Code: red for electric, yellow for gas, oil, steam and petroleum, orange for communication and signal, blue for potable water, purple for reclaimed water and irrigation, green for sewer and drain. Acceptance: photographs of every mark with a reference object for scale and position, taken the day work starts. Wrong looks like relying on marks from a week ago after two rains, because paint fades and flags get pulled by homeowners and mowers. Request a re-mark rather than digging to a memory of where the line was.

Step 6: Work the tolerance zone by hand or vacuum excavation only

Inside the tolerance zone, no mechanical equipment touches soil. The Common Ground Alliance Best Practices recommend a zone of 18 in on each side of the outside edge of the marks, but the enforceable width and whether it is measured from the mark edge or its centerline are set by your state's one-call statute, so use your state's figure. Acceptance: the zone is measured and staked on the ground, and everything inside it is opened by hand digging or vacuum excavation until the facility is visually confirmed. Wrong looks like a bucket used to "just skim" the top foot inside the zone. Stop; a bucket tooth through a coated steel gas main or a service lateral is the single most likely way this trade kills someone.

Step 7: Expose, support and protect anything crossing the pit

Where a facility crosses the excavation, expose it fully by hand or vacuum, support it so it is not left spanning unsupported, and protect it from spoil, traffic and freezing for as long as the pit is open. Acceptance: the facility is visible, supported, and photographed in place before the pit deepens around it. Wrong looks like a line left hanging across an open pit because the crew is working around it; unsupported pipe carrying its own weight plus a shovel strike is a failure waiting for the end of shift. Notify the operator before excavating around their facility where the state statute or the operator requires it, and never move, cut or re-route a facility yourself.

Step 8: Damage response, including damage that looks minor

On any contact with a gas facility, everyone leaves immediately and moves upwind and uphill, no engine is started or stopped, no phone or radio or tool is operated in the area, nobody tries to stop the flow or crimp the line, and the call goes to 911 and to the operator from well clear of the site. On contact with an electric facility, nobody touches the equipment or the ground near it, anyone on the machine stays on it until the operator confirms the line is de-energized, and everyone else is kept well back. On water, close the nearest valve if you can reach it without entering the pit, and call the operator. On fiber or communications, do not attempt any repair and call the operator. Acceptance: every contact is reported to the operator, including a scrape, a dent or a scored coating. Wrong looks like a crew wrapping a nicked line with tape and backfilling, because damaged coating on a steel gas line fails weeks later with nobody on site.

Step 9: Maintain the ticket for as long as the ground is open

Watch the expiry date and request a re-notification before it passes, and request a re-mark whenever marks are destroyed by weather, traffic or the work itself. Acceptance: ticket status current for every day the excavation is open, with each refresh recorded. Wrong looks like a multi-day pier job running past its ticket on the original marks, which in most states is an excavation without a valid notification. Refresh it and keep working; do not backdate anything.

The record this produces

One locate package per job: the white-line photo; the ticket number with legal start and expiry; the notified operator list reconciled against positive responses; the private locate report with its stated gaps; the customer's signed acknowledgment of unlocatable lines; dated mark photos; the hand or vacuum excavation method used in the tolerance zone; photographs of every exposed and supported crossing; every ticket refresh; and any damage report.

The crew lead uses it to decide whether to break ground. The competent person will not release the pit without it, since the excavation SOP's first step is this package. The office keeps it because if a line is damaged, the question asked by the operator, the insurer and the state will be whether a valid ticket was in force and whether the tolerance zone was hand-dug, and this package answers both or it does not.

One worked pass

Six pier pits, rear and side elevations, plus a drain trench along the rear wall. Step 1 white-lined the whole rear yard strip including equipment tracks rather than six individual squares. The ticket went in and came back with four operators responding: gas marked in yellow at the front, electric marked in red along the side, communications clear, water marked in blue at the front meter. Nothing in the rear yard where five of the six pits sit.

Step 4 is where the job turned. The homeowner mentioned a gas grill line and thought it ran straight out from the house. The private locator's electromagnetic sweep picked up a signal at the meter, followed it 22 ft into the rear yard on a line nothing like the one described, and then lost it 8 ft short of the detached shop. The line is poly with no tracer wire, so the trace was riding a coupling and stopped where the metal stopped.

Under step 4's rule that is a partial locate, not a locate. The crew did not dig to the traced portion and guess the rest. The full suspected path across the pit footprint was opened by vacuum excavation, which found the line running at a shallow depth directly through the planned pit at bracket 3, about 5 ft off the path the homeowner remembered. The customer signed the acknowledgment naming the shop line as unlocatable by electromagnetic means before any machine work started.

Bracket 3 could not move without leaving the plan, so under step 7 the line was fully exposed by hand, supported across the pit on cribbing, protected from spoil, and photographed before the pit deepened. The gas operator was notified of the excavation around their upstream service as the state statute requires. The job then ran four days, and on day three the ticket expiry came up: step 9 fired, a re-notification went in, and the rear yard marks were refreshed rather than the crew working another day on paint that was already faded.

What the ticket got right and what it missed is the whole lesson. Every public facility was marked correctly and none of them were anywhere near the work. The one line that crossed a pit belonged to the customer, was invisible to the technology, and was 5 ft from where the person who paid to have it installed believed it was.

References

• Common Ground Alliance Best Practices, for the tolerance zone recommendation and for damage prevention practice; the enforceable requirements come from your state's one-call statute, which sets notification lead time, ticket life, tolerance zone width and positive response.
• APWA Uniform Color Code, for the marking colors used by locators nationwide.
• 811, the national call-before-you-dig number, routed to your state one-call center.
• See related: the excavation and shoring SOP, whose first step is this locate package, and the pier installation standard for the work performed once the pit is released.