Void Detection Over Sewers in a High Traffic Environment

SEI was contracted to perform a GPR survey on approximately 3 miles of storm sewers along two major roadways in Orlando, Florida.  The purpose of the survey was to detect possible voids or loose soils beneath the pavement near areas of subsidence.   

Approximately 15,500 linear feet of transects were scanned using a SIR-20 digital control unit and a 400-MHz antenna.  This antenna was selected for its moderate resolution combined with moderate depth of penetration capabilities.  A Trimble Pro-XR Global Positioning System Unit with real-time data correction was used to record transect locations.

The results of the survey revealed the presence of reflection patterns consistent with possible voids or loose soils in 49 locations over the storm sewers.  The field work was completed within two (2) days, and the reports completed within one (1) week.