Utility mapping is the process of identifying and documenting where underground cables or pipes are located. These underground utilities often include electric wiring, telecommunications lines, natural gas, water lines and wastewater pipes. In some cases, utility mapping might involve oil, natural gas or other fuel lines.

The practice of locating and mapping utilities is essential to civil engineering. It helps prevent the potential extensive loss of money, time and other resources due to accidents. And when project managers are holding an accurate utility map, they can also better project costs.

Why Utility Mapping Is Important

a call before you dig sign">

If you’re in the excavation or construction fields, you’ve no doubt seen the signs: “Call before you dig.”

Damage to utility lines caused by unplanned digging results in costly maintenance and replacements— not to mention service disruption. In some situations, such as damaged fuel or electricity lines, blind excavation can lead to serious injury or death.

When it comes to the business of locating and mapping underground utilities, it’s crucial to know exactly what’s underground, and that means using the proper techniques and tools to provide the highest level of accuracy. Doing so also saves utility mappers time and resources.

Utility mapping does have its fair share of challenges, however.

For years, surveyors have faced numerous problems with map and record accuracy. They’ve also had to deal with hidden objects that go undocumented, making their jobs much more difficult. These challenges are compounded by the use of conventional survey equipment, which is often unreliable for locating inaccessible utility lines that are invisible to the naked eye.

a GPR survey transmitter

Throughout the 21st century, surveyors and engineering teams have discovered new tools and techniques for dealing with the challenges associated with utility mapping. And while the available surveying tools are now numerous and diverse, they aren’t without limitations. For this reason, the most thorough results are obtained when a number of locating technologies are deployed as part of a geophysical survey.

One method commonly used is electromagnetic induction, or EMI. It uses transmitters to send electrical currents through utility lines to induce a primary magnetic field or detects existing fields from live electrical lines. With the help of a receiver, surveyors can pick up the magnetic field’s deflection to locate utility lines. EMI is a very complimentary technology to GPR and is excellent for pinpointing specific lines that have known above ground access points. It’s useful in some situations, but it does have it’s limitations. Metal objects and groundwater can cause serious interference that can makes EMI unreliable.

Magnetometers are often used for locating buried underground storage tanks, however, they cannot be used for fiberglass tanks and generally are not precise enough for accurate utility locating of smaller objects like pipes.

When there are an unknown quantity of utilities that need to be located or services that may be non-conductive or not have access points,  GPR or ground-penetrating radar becomes the preferred tool for utility mapping. The technology is reliable, extremely accurate and compliments other technologies such as EMI. The vast majority of utility locators depend on both GPR and EMI to get their jobs done accurately and efficiently.

How GPR Helps With Utility Mapping

a GPR system

GPR is a geophysical location method that uses electromagnetic waves to locate subsurface objects and structures.

Most GPR solutions come in the form of a pushcart with an antenna, computer and display attached. Operators push the cart over the surface while the antenna transmits the waves into the ground. When the waves encounter objects in the ground, they bounce back to the antenna. These wave interactions are recorded and displayed on a screen.

Utility mappers and surveyors have a much easier time using GPR for their work than many other tools. Since the technology isn’t dependent on external equipment for transmission and measurement, it’s extremely versatile. It works just as well on concrete, pavement, asphalt and rock as it does on ground soil. And since it’s nondestructive, surveying is quick and painless.

The Advantages of GPR for Utility Mapping

two underground pipes are covered in dirt

GPR Is Safe and Non-Invasive

Since GPR uses radar technology, it’s completely noninvasive. Operators don’t have to dig or damage the survey site in any way. With perhaps the exception of marking flags or paint, operators don’t need any external equipment to start collecting accurate and reliable data. With a GPR cart, such as US Radar’s Q5 Utility Locating and Geotechnical Radar System, they just show up to the job site and start scanning.

The noninvasive approach of GPR also means there aren’t any service disruptions when utility mappers are doing their jobs. There’s no need to shut off or disable any utilities in the ground, ensuring no disruptions for utility customers and a safe workday for the operator and the environment.

GPR Detects Any Kind of Object

a large tank for gasoline in an excavated quarry for storage of petroleum products

Ground-penetrating radar technology works by measuring dielectric characteristics within the subsurface material. In layman’s terms, this means GPR units measure the differences between the conductivity of objects in the ground. If there’s an object buried beneath the soil that has conductive properties different from the soil, GPR finds it.

Put simply, GPR effectively locates any kind of utility-related object in the ground, including:

  • Electricity lines
  • Communication lines
  • Water mains
  • Gas lines
  • Piping
  • Valves and shut-offs
  • Underground storage tanks (USTs), septic tanks and leach fields

GPR also picks up disturbances in the soil, such as voids and sinkholes, all with exceptional accuracy.

GPR Is Easy to Use

When you have a quality system, GPR is easy to use. While it does require some basic training, collecting reliable data with GPR is something anyone can learn in a few hours. Since it’s entirely self-contained, there’s no need for additional surveyors at a scan site. One person with a GPR cart is all it takes to collect accurate data for utility maps.

The Limitations of GPR for Utility Mapping

a person digs through mud with a shovel

Despite its many advantages, GPR does face a minor limitation. Since the technology measures changes in dielectric properties of subsurface materials, excessive moisture content in soil makes it less reliable. Moisture and other conductive materials cause the radio waves to dissipate, resulting in decreased penetration depth.

In most instances, this limitation isn’t problematic. For example, light rain won’t interfere with data collection. If you’re planning a survey at a site where excessive rain has fallen, you might need to wait a day or two for things to dry up a little. But in areas with consistently high levels of water, other survey methods may be necessary.

Map Utilities Accurately With US Radar

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If you’re in the business of utility mapping or infrastructure installation and maintenance, you know the challenges and hazards of navigating decades of unreliable utility records and maps. You need a survey solution that operates reliably in any environment and provides accurate visual data that translates into actionable information.

A GPR solution from US Radar does all of this. Our durable units are ready for the wear and tear of any environment, and self-calibrating antennas ensure accurate data collection in almost any soil condition. Our software allows operators to turn the data they gather into highly-detailed utility maps.

For more than 20 years, US Radar has engineered industry-leading GPR solutions for professionals in need of a reliable and accurate tool for utility mapping. With a global network of highly-trained representatives, we have the solutions and the talent to help you get the results you need. Get in touch with us today to get started.