An Electrical Imaging and Resistivity (ERT) survey provides a cross-section of the ground, allowing the different subsurface layers to be identified. This process is commonly known as bedrock profiling and forms part of GEOTEC’s wider geophysical survey services.

The main objective of an ERT survey is often to determine the depth to bedrock, helping clients understand how deep foundation piles may need to extend.

ERT can also identify other layers and features, including landfill material. It may be used after an EM31 or CMD survey to provide greater detail about dissolution features.

GEOTEC has also used this technique to identify the extent of an oil-pipeline leak within a national park.

Electrical Resistivity can achieve a depth penetration of approximately 30m below the ground surface. However, sufficient open space is required to spread the electrode lines at the appropriate horizontal spacing.

An ERT survey is appropriate when a cross-section of the ground is required to identify its subsurface layers, such as the depth and profile of bedrock.

Electrical Imaging and Resistivity can meet a number of survey objectives and can supplement other geophysical approaches by providing greater detail about subsurface conditions.

The site must be suitable for the survey. The achievable depth depends on how far the electrode lines can be spread horizontally, so deeper investigations generally require large, open areas.

Resistivity surveys can also be time-consuming where electrodes need to be drilled into hard-standing surfaces.