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Private Lines Public Locates Do Not Mark

By metal gates round rock works

After the free utility marks go down, a property can look cleared for digging. It is not. The utilities mark what they own, and they stop at the meter or the property line. Everything the owner or a past builder installed on the lot itself stays unmarked: the sprinkler system, the garden lights, the drain pipes, the line to a pool pump, even a buried dog fence wire. Those are the lines most likely to be hit by a post hole drill, because nobody thinks to look for them.

Why the gap exists

Public locators work for utility companies. Their duty ends where the company's equipment ends. A water meter box marks the end of the public side, and the pipe from the box to the house belongs to the owner. The same goes for a gas meter and the line past it, the electric meter base and the cable beyond it. Private lines are legally the owner's business, so the owner has to find them.

Irrigation systems

Sprinkler pipe is the most common victim. Lines are usually plastic, buried a few inches to a foot deep, and they run in trenches along walks, drives and beds. The main line leaves the backflow device or the meter, feeds a valve box and branches into zone lines. Along a street frontage, heads and pipe often sit right where a gate post goes.

• Run each zone and watch where water emerges, since heads mark the ends of lines.
• Find valve boxes, small round or rectangular lids in the lawn, and open them.
• Follow the direction of pipe from each valve, and sketch the route.
• Check the controller for the number of zones and the area each covers.

Plastic pipe cannot be found by an electronic sweep, so the sketch and the heads are the best guide. A probing rod pushed gently into soft ground can feel the pipe.

Landscape lighting and low voltage wire

Garden lights run on a cable from a transformer, often plugged into an outdoor outlet. The cable lies just under mulch or soil, and a spade cuts it easily. Trace it from the transformer to each fixture. A cut cable usually disables a few lights, which is a nuisance more than a danger, but it is still avoidable. Also look for wire to a gate keypad, a doorbell camera or a mailbox light.

Drains and drainage pipe

Yard drains, French drains and downspout lines carry roof and lawn water away. They are often corrugated pipe or rigid plastic pipe in gravel trenches, and they may end at a pop up emitter or a street outlet. Walk the lot after rain and note where water disappears or exits. A line struck by a drill may not look broken until a storm fills it and the soil around a post washes out.

Septic parts and sewer cleanouts

Homes on septic service have tanks, distribution boxes and drain fields that must never be driven over or drilled into. A lid or a pipe cap near the drive may be the only visible sign. County records or the original permit packet show their location. Even in sewered neighborhoods, a cleanout cap in the yard marks the sewer line from the house to the street, and the owner is responsible for that stretch.

Gas, electric and communication runs

A gas line to a grill, a fire pit or a generator, an electric feed to a shed or a pool, and a data cable to a detached garage are all private runs. They may be shallow and unprotected. Look for conduit stubs, marker posts, metal boxes and pipes entering the ground near the house. Power cut by a drill is a serious hazard.

Using plans and records

Builder drawings, pool permits, irrigation designs and prior survey sheets sometimes show private lines. Ask previous owners, the builder or the association for any as built sketches. Photos taken during construction or a landscape project can also reveal buried runs. Compare what you learn with what you can see on the ground.

Hiring a private locator

Private locating companies use electronic receivers that follow metal pipe and tracer wire, and ground penetrating radar that reads non metal pipe. For an entrance with several buried services, hiring one can be a sound investment. Ask what the service can and cannot detect, and have them mark findings with paint that matches the public color code.

Staying careful while digging

Even with all this work, treat any hole as a probe. Start with a hand shovel to a shallow depth, then use the drill. Stop at any sign of pipe, wire, gravel bedding or a color change in the soil. If something appears, expose it by hand, not by machine. A short pause to look is far cheaper than a flood from a broken main or a dark yard from a severed cable.

Once the gate is done, sketch the final post positions and any lines found, and file the drawing with the survey. Future projects, from a new fence to a new lawn system, will be safer because the information was written down.

A walk around the lot

Take a slow walk and list everything that suggests something buried. Valve box lids, round pipe caps, odd patches of green grass, raised mounds, metal posts, conduit stubs on the house wall and wire flags left by past contractors all point to hidden lines. Take a photo of each, then mark them on a sketch of the lot. The sketch gives the crew a quick picture of the risks and gives you a record that outlasts the project.

When the owner does not know

Buyers of an existing home often have no plans at all. In that case, lean harder on the visible clues, on conversations with neighbors who share the same builder and on a private locator. If a doubt remains about a specific spot, shift the post a short distance or hand dig the hole to full depth. Careful extra effort at a few points costs much less than repairing a cut line.