Since its founding in 2001, GPRS has been in the business of helping people avoid subsurface items during groundbreaking activities.
Whether its locating buried utilities, or scanning a concrete slab for rebar, conduit, and post tension cable, our Project Managers are equipped with the knowledge, experience, and technology to help you prevent subsurface damage.
But sometimes the job calls for finding something a client wants to unearth.
GPRS Project Manager Brennan Jeffery recently performed precision concrete scanning and imaging at a building where post tension cable required repair after having been struck and damaged during previous excavation activities.
Then, he visited a home where a floor’s radiant heating system needed to be located and mapped so it could be tied into as part of an expansion.
In both situations, the clients trusted our Project Manager’s industry-leading accuracy and professionalism to help them stay on time, on budget, and safe.
“We can really dial things in specifically for what our clients need,” Jeffery said. “That’s really beneficial for them.”
On the first job, Jeffery was tasked with locating and mapping post tension cable that had been damaged when a contractor was drilling anchors into the slab. A concrete scan was not conducted prior to breaking ground, and as a result the contractor struck and damaged the cable.
Subsurface damage like this is all too common when concrete scanning services aren’t employed prior to cutting or coring a slab. In this case, the contractor got lucky in that the result was only minor post tension cable damage. Had the cable been more seriously damaged, it could have led to a structural failure that endangered the workers on site, anyone in the building, and possibly even nearby community members.
Even though the damage was minimal, repairing post tension cable is a costly, time-consuming endeavor.
“They only hit one of three tendons in a bundle, and so they called us out when they were going to do the repairs,” Jeffery explained. “There were three different locations in the slab where they needed us to scan in order to repair this damage correctly.”
What made this scanning project unique was the fact that the post tension cable spanned the length of two slabs and was tensioned in the middle on a cold joint between the two.
Cold joints are formed primarily between two batches of concrete that are poured and cured at different times. While they don’t typically represent a structural weakness, their location within a structure, the structural function of the element, and aesthetics need to be considered when assessing a cold joint.
“They poured the slab, then they tensioned the cables from edge to edge of that slab,” Jeffery said. “Then there’s like a brace [cold] joint right there. So, we had to find the post tension cables at the joint, and then at both ends, basically, for them to be able to repair the damage correctly.”
GPRS’ primary tool for subsurface investigation is ground penetrating radar, or GPR, a non-destructive detection and imaging method which identifies subsurface elements either underground or within concrete.
GPR can detect both metallic and non-metallic objects, giving it a wide range of applications. It reveals all types of utilities – including electrical conduit, steam pipes, telecommunications lines, gas, oil and water lines, and sewer and storm pipes – as well as the presence of voids, rebar, conduit, post tension cable, and other structural elements hidden within concrete.
Jeffery used GPR to help our client locate the damaged post tension cable so that it could be repaired with minimal disturbance to the concrete slab, and without further damaging any items within the slab.
Just a few days later, Jeffery used GPR to locate and map a radiant heating system embedded within the concrete floor of a home.
This client was looking to tie into the heating system as part of an addition they were building onto the house. The first tool Jeffery usually turns to when locating a radiant heating system isn’t GPR, but instead his Forward-looking Infrared (FLIR) sensor, which can pick up the infrared radiation emitted from the system. However, in this instance the client did not have access to the home prior to Jeffery arriving and was therefore unable to heat the system up sufficiently for it to be detectable with the FLIR.
So, Jeffery turned to GPR to locate the heating system.
“I found it with GPR, and then finally when I was about finished up the slab was heated properly, and I was able to collect some data with the FLIR just to confirm that what I was actually seeing (with GPR) lined up perfectly with those readings.”
Jeffery explained that detecting radiant heating systems within a concrete slab can sometimes be tricky because the mesh placed under the slab for added support while curing often looks identical to the heating elements when looking at the data collected by a GPR unit.
Fortunately, GPRS Project Managers follow the Subsurface Investigation Methodology (SIM) when evaluating and interpreting GPR data. This training standard specifies 320 hours of field training and 80 hours of classroom training, during which trainees encounter real-world scenarios that prepare them for even the most unique challenges they may encounter in the field.
Jeffery said that his SIM-based training equipped him with the tools he needed to decipher what the GPR unit was telling him about the radiant heating system. SIM gives our Project Managers the ability to take a comprehensive approach to every project, tailoring our services to meet the client’s needs.
“I’ve seen a lot of companies just not be able to mark this stuff out at all,” he said. “Either because they don’t really know how to get the right conditions for the FLIR, or they don’t have the right equipment for when it doesn’t work, or they just can’t differentiate it from the mesh because it looks exactly like mesh.”
Whether you’re looking to avoid subsurface items, or zero in on them for repair or renovation purposes, GPRS’ 99.8%+ accuracy rating for subsurface investigation means you’re getting the best utility locating and precision concrete scanning and imaging company to help you Intelligently Visualize The Built World™. And with our nationwide team of 400 Project Managers, our services are always near you.
What can we help you visualize? Click below to schedule a service or request a quote today!