About This ProjectA hole appeared in the centre of Waterloo Gardens behind the Travellers Club revealing a brick vault. The top of the vault was identified at 1m under the surface and was approximately 2m high. The vault was partially filled with soil.
The client requested a ground survey of the gardens to a depth of 5m to determine whether there are other vaults under the ground and the full extent of the vault(s).
- GPR IDS Opera Duo
- Syscal Pro Switch 72
Ground Penetrating RADAR is one of the most common methods used to determine the presence of voids within a structure. It is a Non-destructive techniques method which allows us to assess the wall conditions without any intrusive work. And so to map the route of any chimney flues.
To meet the client requirement, we selected two geophysical methods to provide the best results: a GPR survey and a Resistivity survey.
Ground Penetrating RADAR is a geophysical technique that produces ultra-high frequency (UHF) electromagnetic waves that allow us to map interfaces between subsurface materials with differing dielectric constants.
The purpose of an Electrical Resistivity Tomography surveys is to determine the subsurface resistivity distribution by making measurements on the grounds surface. From these measurements, the true resistivity of the subsurface can be estimated. The ground resistivity is related to various geological parameters such as the mineral and fluid content, porosity and degree of water saturation in the rock.
The resistivity data allowed us to map several possible cavities within the area surveyed. Both GPR and resistivity data were correlated, and same anomalies were mapped with both methods.