Engineering & Environmental Geophysics Overview

Geophysics can be generally defined as the application of physics to investigations of the Earth. Engineering geophysics uses the principles of geophysics to investigate the types of materials and structures below the ground that could be relevant to engineering design, for example the investigation of the subsurface as part of foundation design.

Environmental Geophysics uses the principles of geophysics to investigate the subsurface likely to affect the management of the local environment, for example the investigation of pollution plumes within groundwater.

Stratascan undertakes engineering and environmental geophysics to investigate both rural and urban locations. We use non-invasive techniques to examine the shallow subsurface. Non-invasive investigations mean that we can work without disturbing the subsoil. This is important on environmentally sensitive or busy sites, for example on roads where excavation can cause large scale disruption.

The depth of investigation will depend on the conditions of the site, the type of subsoil and the technique used. In general, we operate within the top 5m of the ground. This depth can be increased but often at the expense of resolution. In carrying out a survey, we are looking for differences in the physical or physio-chemical properties of the subsurface. These 'anomalies' represent a contrast with the parent soils or subsurface materials.

The brick lining and air void of a buried culvert will have different resistances to the surrounding soil. Pollutants within the ground, such as landfill leachate, will be chemically different to the natural soil moisture and groundwater. These chemical differences will cause changes in the conductivity of the soil.

By looking at the character and depth of the anomalies it is possible to gain an understanding of the type of feature that the anomaly represents. For example a broad crested anomaly observed on a radar survey is likely to represent a void or arched structure; a high resistance anomaly observed on a resistivity survey could represent structures like foundation walls. The way that these anomalies are arranged across a site enables us to make an interpretation of what may lie beneath the surface.