A Utility Survey Corp. client was planning on carrying out construction work at a school in New Jersey. He needed to set up a 20-ton crane-lift in the work area, which was a parking lot, and wanted us to scan it in case the weight of the crane were to impact any utilities that might be buried there. Like many clients, this one too, said he didn’t think there could be any utilities under a parking lot. He hired us anyway just to make sure and it’s just as well he did.
Our technician, adhering to our strict ten-step locating protocol, detected and marked out a drainage pipe, and then a high-voltage electric wire coming from a transformer several yards outside of the crane area. The ten-step protocol, developed by Utility Survey Corp., requires scanning with several types of utility locating instruments as well as Ground Penetrating Radar (GPR).
While scanning with one of our latest 270 MHz GPR Cart Systems our technician found the plastic drainage pipe. One of the major features of GPR is it’s ability to detect all kinds of utilities, objects, and features, made from all types of materials such as metal, plastic, fiberglass, concrete and so on. It can even detect non-objects such as voids – and this is where GPR really paid off on this client’s project.
The technician observed a long dark curve on the GPR computer screen. The curve (or hyperbola, to get techie) wasn’t indicative of a typical target image. It would have been easy for the technician to have dismissed it as a ghost-shadow created by the wall of an adjacent building. However, Utility Survey Corp.’s locating protocol requires that all anomalies must be investigated thoroughly. If it is image ghosting being seen, it has to be proven to be such. Nothing can be taken for granted no matter how experienced the technician.
The long curve, upon further investigation by our technician, turned out to be a 600 sq ft disused basement room filled with old junk situated 18” or so below the surface of the parking lot. There was no visible evidence of its existence and no reason to think why a basement should even be there. The significance of this find is that if the contractor had gone ahead and placed the crane where he’d intended, its 20-ton weight of would have collapsed the parking lot, causing the crane to fall into the basement. That would have been an extremely expensive repair job – but, much worse than that, someone could have been seriously injured or even killed.
Utility Survey Corp. technicians are highly trained in our ten-step protocol and must adhere to the carefully thought out procedures that are aimed at maximizing information we can provide for the client and minimizing risk. We are in a high risk business. We do not cut corners. Safety comes first for every single client on every single project. It’s an approach that has served us and our clients well for over twenty years.
Prior to starting this project, our client had made a very common but false assumption in thinking that there couldn’t possibly be anything situated under a parking lot. This assumption is # 3 in our industry white paper report “5 Assumptions That Can Kill Your Projects, Profits, and People” Click here to download and read more about these common but potentially lethal assumptions.
Very fortunately, our client wanted peace of mind before setting up his crane, and went ahead anyway in making the wise decision to hire Utility Survey Corp. And, it paid off in a huge way, if not quite in the way he’d actually intended.
Concrete Structure Scanning
A long-time Utility Survey Corp. client called us to a county prison in New Jersey to help solve a problem for a general contractor client of theirs.
While installing a new security door, the contractor discovered that portions of the block wall had not been grouted properly. The questions was then raised as to whether this was an isolated section, or, was the entire wall compromised? The wall was in a high security area and any weakness in the structure posed a serious security risk. It had to be investigated.
Utility Survey Corp. was asked to bring out our portable, very high resolution, Ground Penetrating Radar (GPR) Concrete Scanning systems to determine if any additional sections of the wall were also improperly grouted.
The results were very revealing. The GPR could “see” where gaps in the grouting appeared to be. For additional confirmation, our client was able to insert a fluoroscope camera into the suspect areas and confirm the GPR’s findings.
Furthermore, the prison authorities then wanted to know why was the grouting incomplete in some areas and not in others? Why was the wall compromised in this way? We were able to provide the answer to this question too. It was essentially carelessness during the original construction. Empty soda cans had been tossed inside the blocking which had then prevented grout from filling those sections of wall and also all sections directly below.
Our Concrete Scanning GPR Survey successfully identified all the problem areas for the client. This ultimately produced a tremendous cost saving as a remediation/repair plan was able to be implemented as opposed to taking down and rebuilding the entire wall.