It’s officially spring, and construction season is ramping up!

If you didn’t know, April is National Safe Digging Month (NSDM). The event encourages homeowners and professional contractors to call 811 before digging or excavating.

It may not seem important, but digging a hole in the wrong spot can create massive headaches. Accidentally damaging cable and phone lines may be inconvenient, but broken gas or electrical lines are dangerous.

The Dirt on Safe Digging

Survey data from Common Ground Alliance (CGA), the organization behind National Safe Digging Month, suggests nearly three-quarters of Americans plan to do some digging on their property this year.

Digging projects aren’t only large-scale excavation projects – they include everything from planting trees and tilling gardens to large-scale excavation. The CGA estimates about 49 million Americans won’t call 811 before starting their projects, putting themselves and others at risk.

But what is 811, and why should you call before digging? Like other “*11” designations, 811 is a nationwide phone number that homeowners, contractors, and companies can call to have areas marked for underground assets by their local utilities.

The process takes several days to complete, but some eye-popping stats make the wait worth it.

According to CGA, accidental damage to underground utilities totals about $30 billion annually in the United States.

Worse yet, about a quarter of reported damages are attributed to not calling 811. Another 22% are associated with late or inaccurate markings. In both cases, homeowners and contractors dig without knowing what’s under their feet.

Breaking Ground on a New Initiative

To cut down on damage caused by careless digging and excavating, the CGA recently launched its “50 in 5” campaign.

The goal is to reduce damage by 50% within the next five years, or 2028. Additionally, the campaign stresses no one is immune to making mistakes. Professional contractors make up about 60% of total damage caused by people not calling 811, so their participation is crucial to the campaign’s success.

How to Locate Underground Utilities

Locating underground assets can be done in several ways, ranging from metal-to-metal contact locating to using ground penetrating signals to find unknown or missing assets.

Figuring out which location technology works best often depends on the type of asset being traced, if direct contact can be made, and if other lines are nearby.

Direct Connection (Conduction)

This highly accurate method of tracing lines involves sending a signal through a metal-to-metal connection, most often through a tracer wire, to find utilities.

A transmitter is attached to the tracer wire at its above-ground termination point – a ground is placed on the other end to receive the signal and complete the circuit. The direct connection allows workers to get the most accurate location data possible, reducing the risk of mismarking. As a result, it’s a popular method of finding cables and pipelines.


Induction locating is used when direct metal-to-metal connections aren’t possible.

Transmitters are placed on top of the soil, sending signals into the ground to find utilities. Because there are no direct connections, induction locating doesn’t need coils or clamps.

Uses for induction locating include finding lost or unknown utilities. It’s also helpful for tracing cables and pipes in areas where several lines converge.

Because there isn’t a direct connection to the line getting traced, the signal may cause electromagnetic coupling. Electromagnetic coupling occurs when electrical energy is transferred between circuits, possibly causing inaccurate results in areas where several utilities congregate.

Ground Penetrating Radar (GPR)

This style of locating uses microwave frequency bands to trace underground objects. Like induction tracing, GPRs don’t need direct contact with metallic and non-metallic assets – instead, signals bounce off the materials back to the machine.

Using a GPR is minimally invasive, meaning it won’t destroy lawns, disrupt traffic, or cause other issues. The machine can also use different systems based on soil composition or utility being traced.

Soil conditions play a crucial role in how ground-penetrating radars work. Sandy and dry soils have low conductivity, making it easier for signals to find assets buried deeper underground. Moister soils and those holding water and/or salt increase conductivity. More conductivity means lower signal strength, resulting in shallower penetration.

Signal frequency is also important. Lower frequencies offer better ground penetration but sacrifice detail. Depending on the depth and quality of the soil surrounding the asset, GPR can be a terrific way to find utilities without damaging property.

Electromagnetic Locators

Electromagnetic (EM) location uses transmitters and receivers to track signals along the utility path. Currents along the asset create a magnetic field picked up by the receiver.

EM signals can penetrate deep into the ground to find buried assets but are especially good at tracking metallic structures. Unfortunately, EM location doesn’t work with High Density Polyethylene (HDPE) or plastic Polyvinyl Chloride (PVC) pipes because they don’t carry a signal. If workers install PVC or other plastic products, including a tracer wire can mitigate the issue and allow the locator to find the line later.

You Found an Underground Utility… Now What?

If you find lines, make sure they’re marked appropriately.

There are several ways to mark underground utilities, including stakes, flags, signs, and painted lines. Feel free to use the method you’re most familiar with.

All markings need to be visible throughout the entire project to avoid accidents. You can use the American Public Works Association (APWA) guidelines to figure out what colors to use for which utilities. For a crash course of which color corresponds to which utility, see the chart below:


Adhering to safe digging practices does more than allow projects to move more smoothly and efficiently.

Whether it’s a home improvement project like building a deck or a large-scale excavation project, contacting 811 before digging prevents damage to utilities, people, and property.

Waiting for the utility companies to show up and mark the area may delay projects for a couple days, but it’s for a good reason. A little planning can prevent thousands of dollars in damage or potentially putting someone’s life in danger.

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