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Ground Penetrating Radar—Identifying Buried Utilities & Structures Before Construction

A construction project requires a carefully thought-out plan to ensure operations go as smoothly and safely as possible. This is especially necessary when construction involves soils, walls and floors. Learn about the utility location processes and what you need to know before construction starts.

Why Locating Is Necessary

An often-asked question is: Why is it necessary to confirm utility locations before starting a construction project? The answer is simple: There may be unidentified utilities and structures buried in soils, floors, or behind walls. Digging, drilling, or tearing down without knowing what’s there can cause extensive and destructive damage. A lot can go wrong fast, which is why confirming and not guessing is the best policy.

Types of Buried Utilities

Some buried utilities are “stand-alone,” however, some are tied into networks that service an entire area or municipality. If damaged, they could create significant problems such as blackouts, interruption of communications, flooding, underground tank leakage, and ground contamination, and in the case of natural gas lines, entire neighborhood evacuations, or explosions. Types of buried utilities and structure scans that need to be located include:

  • Electrical lines

  • Water lines

  • Post-tension cables

  • Natural gas lines

  • In-floor tubing

  • Voids

  • Tanks

  • Rebar

Methods Used for Locating

There are several methods for locating buried utilities, including:

  • Hydro/ Vacuum Excavation

  • Dowsing

  • Acoustic Pipe Location

  • Electromagnetic Location

  • Ground Penetrating Radar (GPR)

Of all locating methods, GPR is the most accurate, less destructive and safest.

The Technology Behind GPR

  • GPR devices are similar in size to a lawnmower. They sit on wheels with its body serving as an antenna. Like a lawnmower, the device’s handle makes for easy maneuvering and coverage of the locating site. When scanning walls, the device is smaller and handheld.

  • GPR technology detects underground objects and the depth at which they are buried by sending using VHF and UHF radio waves into the subsurface of the scanned arear and measuring the travel time bounce-back for the returning reflection of objects. Hand-held GPR devices are used to scan walls.

  • The device determines readings based on electromagnetic radiation and a microwave band, which produce a highly accurate radargram on a screen of what’s buried. These results can also be printed as a map showing utilities and structures in the scanned area.

  • Preventing Destruction GPR’s are effective in most soil types, concrete, or pavement in either horizontal (floors or soils) or vertical (walls) areas. This is due to the streamlined process provided by technology that allows a GPR device to locate and measure the depth of buried items.

Time and Cost-Efficient

Using utility locating GPR before the start of construction will help to save time and avoid budget overruns. In addition, proper utility location shouldn’t take long to complete, and costs are minimal compared to halting operations to repair the damage done during actual construction.

Knowledgeable Operators

Because of its technological complexities, a necessary component of effectively providing GPR utility location is well-trained and knowledgeable operators who know where to scan and interpret the data.

Radio Frequency (RF) Surveys

In addition to GPR, Radio Frequency (RF) surveys provide supplemental information to aid in making decisions during engineering and planning. Both GPR and RF are highly accurate in surveys providing the desired information.

Quality Services

If you need GPR or RF services, make sure to ask the following questions of the locating providers you are considering:

  • How long have you been in business?

  • What is the brand of equipment you are using?

  • What is the training process for your operators?

  • What data will I receive?

  • Do you have references?

Parting Words

No locating process is foolproof, but an approach built on proven technology like GPR, proven in hundreds of thousands of locating hours, comes close.

Learn more about Ground Penetrating Radar (GPR)

To read how GPR has been used in various applications, download one of the project case studies featured below.

Envirologic Technologies

Mapping buried fuel tanks ahead of a potential land purchase.


Locating reinforced steel inside walls needed in prep for mechanical changes to preserve structural integrity and prevent damage to the site.


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