Underground Utility Locate Before Digging

Purpose

A deck crew digs a small number of deep, narrow holes at the back of a house, which is exactly where the gas service, the irrigation main, the pool feed, the septic line and the sub-panel run to the detached garage all live. An auger in a 42 inch frost-depth hole reaches every one of them, and it reaches them at full torque with an operator leaning on the handles.

This procedure guarantees two things. First, that a one-call ticket exists, is current, and covers this dig on this date. Second, and this is the half that actually prevents the strike, that the crew knows what the ticket does NOT cover: the tolerance zone around each mark, and every privately owned line past the meter, which no one-call center marks and which is most of what a deck crew hits.

Scope

Covers the one-call notification, the mark verification on arrival, the tolerance zone rule, private utility locating, and what happens when a line is struck or exposed. Applies to every hole, trench, stake and ground screw on a deck job, including a single post replacement.

Does not cover the excavation itself, footing sizing or the open-hole inspection; the footing layout SOP owns those and calls this one as its gate. Does not cover overhead lines, a separate hazard with its own clearance rules. Does not resolve which notice period and tolerance zone your state's damage prevention statute sets; step 1 makes you read them.

Roles and responsibilities

Procedure

1. Read your state's damage prevention rules once, and write the numbers on the job template. Get your state's required advance notice, ticket life, tolerance zone width and any positive-response requirement from the one-call center. Acceptance: those four values written on the shop's job template with the state named beside them. Wrong looks like a crew working from "two days and eighteen inches" carried across from a state they used to work in. Stop rule: unknown values mean nobody digs until the one-call center supplies them. This is the step shops without a strike history reliably skip.

2. File the ticket with a description that matches the actual dig. Describe the work as deck footing excavation, with the depth, the count of holes and the area referenced to the structure. Acceptance: a ticket number in hand, the required advance notice satisfied in working days excluding weekends and holidays, and the described area covering every hole on the layout. Wrong looks like a ticket describing "back yard" on a property where holes also run down a side yard. Stop rule: if the layout changes after filing, amend or re-file before digging the new location; a ticket does not stretch. Hazard: a ticket that does not cover the ground you dug is the same as no ticket when the claim is written.

3. Have private lines located separately. One-call marks facility owners' lines to the meter or point of service. Everything past that, the gas run to the fire pit, the pool equipment feed, irrigation zones, low-voltage lighting, the septic tank and field, the well line, the sub-panel feed to a shed, is the owner's and gets no marks. Acceptance: either a private locating contractor's marks and report on site, or a signed customer statement listing known private lines and acknowledging that unlisted ones are unmarked. Wrong looks like relying on a homeowner's memory of a pool a previous owner installed. Stop rule: a property with a pool, a powered detached structure, irrigation or a septic system does not get augered on customer memory; hire the private locate. Hazard: private gas runs to fire features are commonly shallow and unmarked, so treat suspected private gas as live and do not auger within the tolerance zone of a fire feature.

4. Verify the marks on arrival, before any tool comes off the truck. Walk the site with the layout, find the paint and flags, and read them against the APWA color code: red for electric, yellow for gas, oil or steam, orange for communications, blue for potable water, green for sewer and drain, purple for reclaimed water, white for the proposed excavation you marked, pink for temporary survey. Acceptance: marks present, legible, and consistent with the facilities you can see above ground, meaning a gas meter has a yellow line leading to it and a detached garage with lights has a red one. Wrong looks like a gas meter on the wall and no yellow paint anywhere. Stop rule: a facility you can see with no mark leading to it is an incomplete locate; call the one-call center for a re-mark and do not dig that area. Hazard: none in walking the site, and this is the last cheap moment on the job.

5. Re-mark before the ticket expires, and after weather. Track the ticket's remaining life against the schedule and request a re-mark before it lapses, or whenever rain, mowing or traffic has taken the paint off. Acceptance: marks legible on the day of the dig, ticket unexpired on that date. Wrong looks like faint ghosting the crew decides to interpret. Stop rule: faded or missing marks mean no excavation until they are refreshed, however sure anyone is about where the line was. Hazard: this is the most common paperwork route to a strike, because the marks were right and the calendar moved.

6. Honor the tolerance zone at every hole. Apply your state's tolerance zone, commonly the width of the facility plus a set distance each side, measured from the outside edge of the mark. Acceptance: no powered excavation of any kind inside that zone; holes inside it are opened by hand or by vacuum excavation until the facility is exposed and its depth recorded. Wrong looks like an auger started outside the zone and walked into it as the operator chases plumb. Stop rule: if a hole must land inside the zone and cannot move, expose the line by hand first, then decide whether the footing moves or the design changes. Hazard: hand digging near a live electric service still carries shock risk, so use insulated-handle tools, keep a second person present, and stop at first contact with anything hard rather than levering against it.

7. Move the hole rather than the line. When a footing lands on or beside a facility, take the design change over the excavation. Acceptance: the relocated footing still satisfies the beam and joist layout, and the designer has confirmed the new tributary loading if a post spacing changed. Wrong looks like a footing shifted 18 inches to clear a gas line with nobody re-checking the beam span. Stop rule: any post spacing change goes back to the designer before the hole is dug; the beam span table decides this, not the auger.

8. Expose, support and record any facility you uncover. Photograph an intact exposed line, record its depth and type, and support it so it is not left spanning an open hole. Acceptance: depth and type written into the footing record, the facility supported before concrete goes near it, and the owner notified if the facility is theirs. Wrong looks like a cable left hanging across an open hole overnight. Stop rule: an exposed facility with damaged coating or sheathing is reported to its owner before backfill, even if it still works. Hazard: never use an exposed line as a step, a lever or a tool rest, and never encase a facility in concrete.

9. Act on a strike in the right order, hazard first. On any contact with a gas line, everyone leaves the area immediately and moves upwind and uphill, nobody starts an engine or a vehicle, nobody uses a phone or a light switch within the area, and the call to 911 and to the gas utility is made from a distance well clear of the leak; do not attempt to stop the flow or plug the line. On contact with an electric line, nobody touches the equipment or the ground near it, the operator stays on the machine if it is energized until the utility says otherwise, and everyone else stays back beyond any visible arcing or ground disturbance. On water or sewer, shut down the excavation and call the owner. Acceptance: the area is clear and the correct owner and emergency number have been called. Wrong looks like a crew standing over a hissing hole discussing it. Stop rule: the job stops for the day; nobody backfills a struck facility.

10. Close the ticket into the job record. Before the crew leaves, put the ticket number, the mark verification result and any exposure or strike into the job file. Acceptance: the ticket number appears on the footing record for every hole dug that day. Wrong looks like a ticket that lives only in the office email. Stop rule: no ticket number on the footing record means the record is incomplete and the job does not close out.

The record this produces

• Ticket number, filing date, valid-from and expiry dates, and the described dig area.
• The step 4 verification: who walked it, on what date, which colors were present, and any facility seen above ground with no mark.
• Private locate report or the signed customer statement of known private lines, plus any re-mark requests and their dates.
• For each exposed facility: type, measured depth, photo, and whether the owner was notified.
• Any strike, with time, facility type, who was called, and the outcome.

The office reads it if a damage claim arrives, and a ticket number with a dated mark-verification note is the difference between a claim you defend and one you pay. The estimator reads it on the next job at that address, because a house with an unmarked private gas run to a fire pit still has one.

One run, including the stop that fired

Job: 12 foot by 14 foot attached deck at the rear of a house with a gas meter on the side wall, an in-ground pool, and a detached garage with power. Six footings, design depth 42 inches, augered.

Step 1 values from the state one-call center were already on the job template. The office filed on a Monday, describing rear and side yard deck footing excavation to 42 inches, six locations, with the required advance notice landing the dig on Thursday.

Step 3 fired the first stop. The property has a pool and a powered detached garage, so under this SOP customer memory does not clear it. A private locator was scheduled for Wednesday and found two facilities the one-call marks did not carry: a pool equipment feed running diagonally across the rear yard, and a low-voltage lighting run. The pool feed crossed the marked position of footing 4.

Step 4 on Thursday found red, yellow and blue marks present and consistent with the meter and the garage. Step 6 put footing 4 inside the tolerance zone of the pool feed, so it was hand dug, and at about 30 inches the crew exposed the conduit intact.

Step 7 then governed: rather than route around it at depth, the lead called the designer, who moved footings 4 and 5 to change the beam post spacing from three equal bays to two and confirmed the beam size still worked at the new span before either hole was dug. Step 8 recorded the conduit at 30 inches with a photo, supported it, and it was backfilled undamaged.

The cost was one schedule day for the private locate and about three hours on the day for the hand dig and the design call. The alternative was an auger into a live pool circuit at 30 inches with an operator's hands on the machine.

References

• Call 811 before you dig, the national one-call number; your state's damage prevention statute sets the advance notice, ticket life and tolerance zone
• APWA Uniform Color Code for temporary marking of underground facilities
• OSHA 29 CFR 1926.651(b), determining the location of underground installations before opening an excavation, and locating them by safe and acceptable means as excavation approaches
• Common Ground Alliance Best Practices, damage prevention practice for excavators and facility owners
• See related: the footing layout and inspection readiness SOP, which calls this procedure as its step 3 gate