What Contractors Should Check Before Digging Near Underground Lines

Most underground line strikes trace back to a planning gap, not a careless operator. A crew shows up with the right equipment and a clear work order, but nobody checked whether an old drawing exists, whether a private irrigation line runs through the yard, or whether the locate ticket that was called in three weeks ago actually covers the area they're digging today. The equipment and the operator were never the weak link — the information they were working from was.

Pre-dig research is the work that happens before anyone requests an official locate: pulling together what's already known about a site so the locate request is accurate, the crew briefing is specific, and nobody is digging on assumptions. It does not replace official locates or physical verification — nothing does — but it changes what those steps are working with. A locate request built on a five-minute address lookup produces a different result than one built on a reviewed set of drawings, prior project notes, and a walk of the site.

This guide covers the full sequence: what to check before you request a locate, the difference between desktop research and the official locate process, how to spot the private and undocumented lines that public records miss, how to brief a crew so the research actually reaches the people digging, and what to do when field conditions don't match the plan.

These two get conflated constantly, and the confusion is where a lot of risk hides. Desktop research is everything you can learn before anyone marks the ground: public utility maps, drainage records, uploaded site plans, previous project files, owner-provided drawings, and survey notes. It answers "what do we already know, and what do we still need to find out." It's planning work, and it happens at a desk or in a truck before the crew mobilizes.

An official utility locate is the required field confirmation. Depending on the jurisdiction, that's a regional one-call center, a dial-before-you-dig process, direct coordination with a utility owner, or a private locate service for lines a public system doesn't cover. In the United States, the national number and portal for this is 811 — regardless of state, calling 811 or submitting a ticket through it is the starting point for a legally required locate, typically a few business days before you plan to dig. It answers "where are the utilities, physically, right now," and it's the step that actually authorizes you to proceed.

Desktop research makes the locate request better — you know what to flag, what area to mark, and what to ask about. It does not make the locate optional. If research and the physical locate ever disagree — a drawing shows a line running one way and the field marks show something else — that disagreement is a reason to stop and get it resolved, not a reason to trust whichever one you saw first.

Start narrower than the mailing address. Confirm the parcel, the access points, the proposed work zone, and any nearby lanes, easements, or shared service corridors that could be affected. On corner lots, multi-building sites, and industrial yards with several entrances, the mailing address alone can point a crew at the wrong section of the property entirely.

The planning area needs to match the actual footprint of the disturbance, not just where the finished work will sit. Include staging areas, trench routes, bore paths, spoil piles, and equipment access — anywhere ground gets disturbed, even temporarily. If the scope changes after the locate request goes in (a wider trench, a relocated bore path), the locate may need to be updated too. A site plan built in SiteBuildHub makes this boundary explicit and easy to share with whoever is requesting the locate, instead of relying on a verbal description of "the back corner."

Pull together whatever records exist for the site: public utility maps, drainage and sewer records, prior survey files, owner-provided drawings, engineering packages, and as-built documentation from earlier work. The goal isn't certainty — desktop records are frequently incomplete or approximate — it's building a planning picture accurate enough to brief a locate request and a crew.

Look specifically for gas, electric, water, sewer, storm, communications, and irrigation lines, and pay attention to direction changes, material transitions, older alignments, and anything that looks abandoned or unclear. A record that's hard to interpret is not the same as a record that's wrong — flag it and move on rather than guessing at what it means.

Public utility records cover public infrastructure. They routinely miss private laterals, owner-installed irrigation, yard lighting circuits, outbuilding power runs, and older service lines from work that predates current permitting. None of that shows up on a locate ticket unless someone specifically requests a private locate or the owner discloses it.

Treat a clean set of public records as a starting point, not a clearance. If the property has older structures, additions, complex drainage, industrial equipment, or any history of DIY work, flag those areas as higher risk regardless of what the public locate shows. The fix isn't more paperwork — it's a direct question to the owner ("has anything been run through this yard that wouldn't be on a utility map"), and where the answer is uncertain, potholing by hand before mechanical excavation gets anywhere near the suspect area.

The most common way good research fails to protect anyone is that it never leaves the person who did it. A screenshot in one text thread, a PDF in someone's email, a handwritten note in a truck console — none of that reaches the crew standing at the trench line. Centralizing site plans, drawings, screenshots, and notes into one project record is what turns research into something a crew can actually use.

This is exactly the gap SiteBuildHub's Reports feature is built for — pulling project notes, uploaded site plans, and risk flags into one record that a supervisor can hand to a crew instead of reconstructing the story from memory every time. If you're starting from a rough sketch or an old drawing rather than a clean plan, Photo-to-Site-Plan turns a job-site photo into an editable draft you can annotate with what you found during research, and a full project draft can be started any time in SiteBuildHub Draft.

Once the work zone and known risks are documented, request the official locate through the process required in your jurisdiction — call811.com in the U.S., or the applicable regional system elsewhere. Provide the actual work zone from your research, not just the address, and flag any private-line concerns explicitly so the request routes correctly.

Locate timing is a scheduling risk, not a paperwork formality. Most systems require a few business days' notice, tickets can expire, and a scope change after the ticket is submitted may require a new request. Keep the locate status — requested, completed, expired, needs update — visible in the same project record as the research, so nobody on the crew shows up assuming a ticket is active when it's actually lapsed.

The sequence below is the same one described above, laid out as a repeatable process. Running it in order — instead of skipping straight to "call it in" — is what turns pre-dig planning from a formality into something that actually catches problems while they're still cheap to fix.

A fence contractor is quoting a 180-foot backyard fence replacement. The public utility locate comes back clean — no gas, electric, or water conflicts along the line. On a routine job, that would be the end of the research. But the site walk turns up a detail worth flagging: an older detached workshop in the back corner with a visible exterior light fixture, on a property where the current owner mentions they "think" a previous owner ran power to it years ago.

That's a private-line flag, not a public-locate finding, and it wouldn't have surfaced from the locate ticket alone. The contractor notes it in the project record, asks the owner directly whether they have any documentation of the run, and — getting no clear answer — plans to hand-dig the section of the fence line closest to the workshop instead of running the auger through it blind. The rest of the run proceeds on the mechanical schedule. Nothing dramatic happens, which is the point: the flag turned an unknown into a five-minute precaution instead of a struck line.

A handful of mistakes account for most of the risk that pre-dig research is supposed to catch:

Research that never reaches the crew doesn't reduce risk. Before excavation starts, brief the team on the work zone, what's known versus uncertain, locate status, flagged private-line areas, and the specific conditions that mean stop and verify rather than keep going. The briefing doesn't need to be long — it needs to be specific enough that someone can act on it without calling the office first.

Set the stop-work triggers explicitly: an unmarked line, a surface feature that doesn't match the plan, damaged or missing locate marks, or any field condition that conflicts with the research. Stopping to verify costs minutes. A struck line costs a repair, a possible outage, a delayed project, and — depending on what's hit — a genuine safety incident. That trade is not close.

Once the work is done, keep the research, locate references, field notes, and any as-built conditions with the project record rather than letting them disappear once the invoice goes out. The next contractor working at that address — possibly you, on a follow-up job — benefits directly from knowing what was already confirmed. This is one of the more overlooked returns on centralizing research in the first place: it isn't just for the current job.