Minimizing Sinkhole Damage: Where are the Voids?

I see this on TV all the time:


That news story is usually accompanied by a picture of a massive sinkhole causing catastrophic damage. How did that sinkhole just happened to cave in? It was probably in the making for quite some time. Typically, sinkholes start with a small void that gradually increases into a cavern that eventually collapses the sewer and surrounding area and utilities.

Recently, one of our clients discussed a meeting with decision makers who wanted to know why road repair and paving budgets were increasing, while the interceptor inspection and rehabilitation programs have been increased each year as well. Weren’t the repair expenses supposed to decrease as inspection increased? The problem, he pointed out to us, are the “voids” — those tiny cracks that turn into sinkholes.

Having the ability to detect voids would allow for preventive measures to be implemented before it’s too late. An ideal way to detect a void would be to have the ability to “see through the sewer pipe from within the sewer,” detect areas of concerns, and take corrective action before the void becomes a collapse or sinkhole. This was a recent topic due to a sinkhole that caused major damage in an urban downtown area.

Here at RedZone, we provide multi-sensor inspection. While performing standard CMOM or compliant inspections, why not inspect for as many problems as possible?

We are currently investigating the use of Ground Penetrating Radar (GPR). GPR employs microwave-band electromagnetic radiation to examine subsurface structures. GPR has historically been useful in locating subsurface objects. The sensor transmits short “pulses” or “waves” of microwave radiation into the ground. Transmitted waves propagate through the soil until they hit a buried object and are reflected back to the surface to be detected by the GPR receiver. The secret to this sensor would be to mount on the Responder Robot, collect the information while the pipe is in service, and use it in sync with the entire suite of condition assessment sensors (Sonar, LADAR, H2S and CCTV).

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