We were contacted by Pear Tree Primary School to conduct a buried obstruction survey as a precaution before they began excavation.

Our findings from this survey will allow our client to plan around any underground utilities and gather accurate costings for working around them.

What Is a Buried Obstruction Survey?

Buried obstruction surveys allow us to see what’s lying underground without the need for digging an area up and potentially causing damage to the scanned surface or the buried objects.

These surveys allow us to identify any buried obstructions early, avoiding any surprises that will cause delays further into the project.

How Does It Work?

To conduct buried obstruction surveys, we use a Ground Penetrating Radar (GPR). GPR’s are a non-destructive, non-intrusive detection and imaging method that identifies subsurface elements that are either underground or within surfaces – for example, within concrete.

The GPR sends a radio signal to a surface and reads the ‘bounce’ (the time the signal takes to return back to the GPR). This ‘bounce’ indicates the distance between the underground surface and the GPR.

What Did We Do?

Using GPR technology, we collected information at 0.5m intervals of the areas highlighted in the 1938 map and processed the data to look for anomalies in the ground. 

To interpret the data, we used historic maps and the GPR data collected on site. This data was then extracted into CAD and any patterns or clumps of data were grouped together with an average point depth identified.