Past Projects:
Void Detection – Arizona Electric Power Cooperative

Void Detection

Client Problem

On-site personnel, had concerns of possible voids in 5 particular areas throughout the AEPCO. These concerns arose due to multiple water lines bursting and with the amount of water that was released they are taking extra precautions to make sure there is no cave-ins. The area of concern has a large load capacity as cranes come in that area often. Site personnel wanted us to come out and perform a Void Survey to determine the size and locations of the possible voids.

How We Responded

The development of voids beneath concrete is a serious hazard, making their early detection an important aspect of infrastructure maintenance and remediation.  Early identification of concealed subsurface voids under a concrete structure is critical to prevent major failures from occurring. One of the most effective tools in use is Ground Penetrating Radar (GPR). GPR has advanced to a level where the subsurface condition can be diagnosed with confidence.  GPR is a non-destructive geophysical device used for subsurface exploration and operates by transmitting an electromagnetic pulse from an antenna into the ground and then capturing the partial reflections from subsurface layers.

Results We Delivered

Significant anomalies adjacent to the water pipes was found. There was a clear change in
the GPR image at these locations. The anomaly showed a significant drop in material
dielectrics. Based on the reflection pattern, it was suspected to be a void. Based on the
GPR image, the size of the suspected void was estimated to be significant. Tools and
Methods Used to Gather Data; A 400 MHz GPR antenna was used to survey and map the
subsurface condition. GPR data was collected in the longitudinal direction parallel to the
faulted joint and at selected transverse locations. The reflections from the rebar are
readily visible as a series of hyperbolas.

Client Savings

Concealed voids in the subsurface of concrete structures may pose a safety hazard due to sunken concrete and/or structure collapse. Therefore, it is critical to identify the existence, location and size of the voids. It was found that GPR can be utilized effectively to detect subsurface voids.


Contact Us To Learn More

Encompass Inspections offers Ground Penetrating Radar/Concrete X-ray, Underground Utility Locating, Video Camera Inspection and Leak Detection services.  For more information on our equipment and services.  Refer to our equipment page for more information.

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