GPRS was called out to a prison to provide utility mapping services – after a contractor had hit a 15,000-volt electrical line while trenching.
The contractor was trenching to install a new power duct. While existing as-built documents indicated there was an electrical line in the project area, the location of that line was off by about 20 feet, which resulted in the contractor striking the utility while excavating.
When Project Manager Jacob Hardy arrived on site, he saw with his own two eyes the damage caused by the utility strike, which actually fused the sand around the excavation into a glass-like rock called fulgurite.
“The previous contractor who had been there before, they were just going off of as-builts instead of calling a private utility locator,” Hardy said. “So now I think [the prison] is just requiring their new contractors coming in to call [us].”
Historical as-built documentation is rarely an accurate reflection of the infrastructure below your feet. It’s more of an “as-intended” look at how utilities, underground storage tanks (USTs) and other objects were supposed to be arranged. But natural obstacles, pre-existing infrastructure, and other factors often require last-minute modifications that aren’t noted in the plans.
As evidenced by what happened at the correctional facility, relying on existing as-built documentation when breaking ground can result in costly and potentially dangerous damage to underground utilities. According to research conducted for GPRS in 2021 by the consulting firm, Finch, the average cost to repair a single utility strike is approximately $56,000. That number doesn’t consider the additional consequences of damaging utilities that keep a secure facility like a prison operational.
Your first step when planning to excavate is to follow the law and call your local 811 center to obtain the approximate location of registered utilities in your project area.
But because not all utility companies are registered with 811, you should also hire a professional utility locating company like GPRS to provide you with accurate, complete utility locating information before you put a shovel or bucket in the ground.
At the prison, Hardy used an electromagnetic (EM) locator and ground penetrating radar (GPR) scanner to map the electrical line and all other buried utilities in the project area.
EM locators detect the electromagnetic signals radiating from metallic pipes and cables. These signals can be created by the locator’s transmitter applying current to the pipe, or from current flow in a live electrical cable. They can also result from a conductive pipe acting as an antenna and re-radiating signals from stray electrical fields and communications transmissions.
GPR units emit radio waves into the ground or a concrete surface, then detect the interactions between those waves and any buried objects. These interactions are displayed in a readout as a series of hyperbolas that vary in size and shape depending on the type of object located. GPRS Project Managers are specially trained to interpret this data to provide accurate utility locating information, including the approximate depth of the buried object.
By utilizing both EM locating and GPR scanning, Hardy was able to locate and map the buried utilities running through the project area. And to help ensure the prison doesn’t suffer any future utility strikes related to those lines, this data was uploaded into SiteMap® (patent pending), GPRS’ proprietary project & facility management application that provides accurate existing condition documentation to protect both assets and people.
All GPRS clients receive complimentary SiteMap® Personal access when they hire GPRS to conduct a utility locate. This means that they have 24/7, secure access to the critical infrastructure they need to plan, design, manage, dig, and ultimately build better.
Whether it’s a prison’s electrical system, or a skyscraper’s post-tension cable layout, GPRS Intelligently Visualizes The Built World® to keep your projects on time, on budget, and safe.
What can we help you visualize?
Frequently Asked Questions
What do I receive when I hire GPRS to conduct a utility locate?
Our Project Managers mark and highlight our findings directly on the surface, ensuring the most precise communication when excavation is set to begin within days.
Additionally, GPRS utilizes a global positioning system (GPS) to capture data points of our findings. This data allows us to create plans, KMZ files, satellite overlays, or CAD files, preserving results for future reference. Please note that GPRS does not offer land surveying services. If land surveying is required, we recommend consulting a licensed professional.
Contact us to explore pricing and marking options tailored to your project needs.
Can GPRS locate PVC piping and other non-conductive utilities?
Yes, GPR scanning is exceptionally effective at locating all types of subsurface materials. And when PVC pipes do not provide an adequate signal for GPR, our Project Managers are trained to use complimentary technologies like electromagnetic (EM) locating to compensate.
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