FAQ

GPR stands for Ground Penetrating Radar. Although GPR is only one of the many powerful tools and methods we utilize, it's the one that sets us apart from other underground locating services (such as 811) who do not utilize GPR when locating utilities.

GPR fires pulses of microwave frequencies into the ground and the reflection of these waves back to the GPR gives information on objects below the surface to the GPR operator. When radio pulses are fired into the ground, the pulses reflect back to the GPR at different rates depending on the materials and shape of objects present in the ground, the computer translates these unique reflections into a visual representation of the data that is discernable by our technicians. Objects like conduits can be located with GPR because their material composition and shape differentiate them from the ground around them as seen in the reflection data.

No, GPR does not transmit frequencies powerful enough to be harmful to the operator, anyone nearby or to the environment. GPR does not interfere with even the most sensitive technology or communication systems. We work in electrical substations, data centers, near cell towers, at airports, manufacturing plants and hospitals with no issues.

Yes, it can be utilized for locating utilities inside although, factors such as steel reinforced concrete slabs, frequency interference, trace signal bleed off and physical obstructions can greatly reduce our locating effectiveness with EM equipment and large antennae GPR when used inside. Concrete slabs can always be thoroughly investigated with our concrete scanning process (link to concrete scanning page) but locating utilities below steel reinforced concrete slabs inside a building have their limitations depending on what utility it is, how deep it is and the other limiting factors listed above however, we do frequently and effectively locate underground utilities inside.

The colored markings you see on some streets and sidewalks are coded messages for construction crews who will soon be digging in the area. The colors used in the APWA Uniform Color Code are Orange, Pink, Yellow, Green, Red, Blue, and White. The markings are painted by a professional utility line locator, and the color of each marking tells workers which utilities to watch out for when digging in the area.

Orange: Communication & Community Access Television (CATV) cables. These are vital lines of communication that can also be used for alarm systems and more.

Pink: Temporary Survey Markings. These pink markings are used to draw precise lines between the legal boundaries of adjacent properties.

Yellow: Gas, Oil, Steam, and Chemical lines. These are the pipes that deliver fuel for heat and other purposes to homes, businesses, and other buildings in the area.

Green: Sewers and Storm Drains. Needless to say, you do not want to dig up sewer lines during an important construction project.

Red: Electrical, Conduit, and Lighting Cables. Digging up these utilities would be dangerous, and could produce shocking, potentially fatal consequences.

Blue: Potable Water. The pipes beneath blue markings on the pavement are responsible for delivering water for drinking, bathing, cleaning, and more, to buildings in the area.

White: Proposed Excavation. These white markings don’t tell you what’s underneath the pavement — only that a construction crew plans on digging in the area at a future date.

Check out our guide to color-coding underground utilities for more details about this subject!

We follow the American Public Works Association (APWA) Uniform Color Code using ANSI/NEMA standard Z53.1 as shown below:

Pipe, cable, and tank locating, including, but not limited to electrical cable locating, communication cable locating, sewer main locating, gas line locating, water pipe locating, storm drain locating, septic systems, and underground storage tanks (USTs).

Yes.  When purchasing an older existing residence we can locate underground storage tanks that were used to hold fuel oil or septic systems that need to be repaired.  We have located drain pipes, electrical lines, water pipes, and cable lines for homeowners planning on additions and improvements.

GPR OneCall is a fully insured utility locating company, carrying $1,000,000 in professional liability insurance, commercial liability insurance, workers compensation insurance, and commercial auto insurance. Proof of insurance is available upon request.

Our Safety and Training page highlights the extensive training that our Technicians have undergone.

Our goal is to offer the best quality private utility locating while keeping our rates as low as possible. Every job is unique and requires our review to determine the appropriate equipment and how many Technicians will be needed.  We typically have a two-hour minimum charge and we can provide a flat fee quote on request. GPR OneCall reserves the right to adjust our hourly minimum and/or rates based on the complexity of the project, distance, increased liability, and other factors as deemed applicable. Projects requiring an overnight stay will typically require additional charges.

Yes, we can provide a basic written description report for any job if requested.  We can also provide photos, DGPS data (+/- 1.5m), and a site sketch (not to scale) but it would add approx $300 to the total cost and we would need to know before the job starts.  Normally this is only requested when we are assisting in the preparation of a survey or initial site plan.  In most cases, as with other environmental jobs we have completed, the surveyor that locates the probe holes, drill holes and wells will also handle the paint mark locating because they will have more accurate DGPS coordinates and then they will be able to map the data to scale on the survey or site plan they are preparing.

No, residential utility locating is usually less complex, requires less time, and generates less liability for our company, so fees are typically less for residential utility locating.

For residential services, payment is generally required at the time of service. Major credit cards and cash are accepted as payment. Invoices will be issued to commercial clients in good standing, however, payment is considered due thirty days after the date on the invoice. New commercial clients may be asked to provide payment at the time of service.

811 should always be called before you dig – it’s the law! However, 811 does not often locate all of your utilities. Once a utility passes through a metering device or other main connection point on your property, it’s considered privately owned and detection becomes your responsibility – this is where GPR One Call comes in.

Many industrial complexes have privately owned utilities between buildings that 811 does not locate.  By using GPR OneCall to locate these types of private underground utilities you can avoid design issues, large repair bills, unproductive downtime, and most importantly, prevent worker injuries.

Unless you want to pay a hefty fine to the government, you must call 811 at least three days before digging. If you don’t call before digging, you also risk damaging underground utilities, which will cost you even more than the fines you’ll get for failing to call. Calling 811 will cost you nothing, and it will help you avoid costly damage that could delay your construction project — so there’s no reason not to call 811 before digging!

Main gas lines are usually buried no less than two feet below the surface. Service lines are closer to the surface, generally about 18 inches deep. The depth of underground utilities typically varies depending on various factors, such as the specific location and local regulations.