Unexpected Setbacks When Excavating - Using GPR For Mitigating Risk: A Case study

Whether constructing on undeveloped land or on an existing developed site, there is a risk of encountering unexpected objects when excavating. With today’s technology in Ground Penetrating Radar (GPR), this risk can generally be mitigated. Using Whiting-Turner’s construction of Stanford University’s new ChEM-H & SNI Building as an example, this case study discusses the use of GPR for underground mapping, as well as various ways to implement GPR technology. The ChEM-H & SNI site had many underground utilities that required precise pot-holing to verify locations. Although pot-holing is widely used, it is a destructive method, it is time and labor intensive and can easily miss buried objects (“hit or miss”). Thus, this paper researches Ground Penetrating Radar (GPR) to determine if the technology would have been a viable option for Whiting-Turner to identify and locate the underground utilities at the subject site prior to excavation. GPR is geophysical method that uses radar pulses to image the subsurface. This method can identify a variety of media including rock, soil, ice, water, structures, utilities and sewer systems, and it is nondestructive