Brownfield Site Investigation using Geophysics

Most former industrial sites have a legacy of buried structural hazards and contamination. Geophysical surveys can detect buried targets without the need to excavate. Many industrial contaminants, such as salinisation by acids and hydrocarbon plumes, can leave a significant geophysical imprint on the subsurface that can be imaged.

Mapping subsurface structures consists of an initial survey using a combination of metal detection, magnetic, electromagnetic and ground conductivity mapping. These techniques target both direct (i.e. metal supports/pipes, rebar, foundations, etc.) and indirect (i.e. variation in the backfill material, trench fill, etc.) subsurface geophysical properties.

More detail on geophysical targets in terms of depth, size and lateral extent can be achieved by following up using methods such as ground radar (GPR), resistivity tomography and microgravity techniques.

TerraDat is able to acquire data rapidly across large areas by utilising bespoke carts mounted ATVs with real-time positioning provided by RTK GPS systems. This provides us with coverage rates of up to 6ha a day, depending on site conditions.

The data is provided as plots showing anomalies’ distribution across the site overlay with the site topographic plan. These are also transposed into AutoCad to provide the Client with accurate DWG or DXF plans showing the locations of buried structures.

Recent Surveys include:

Mapping buried structures, former refinery, London Gateway, Essex
Mapping buried structures, former textile mill, Trowbridge
Geophysical survey to detect buried structures, former munitions factory, Avonmouth
Mapping foundations, Innovia films factory, Bridgwater
Survey to Detect Underground Structures at the Site of a Former Tinplate Works, Abercarn

The photo above shows a typical survey setup with the survey instrument mounted on a bespoke cart and towed behind a quad-bike. The resulting data plots are displayed on the right and show, from top to bottom, magnetic data, ground conductivity and a combined interpretive AutoCad DXF showing the locations of the anomalous features. This is presented as part of a written, factual report alongside further interpretive figures.

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Page categories:

Applications, Energy & Natural Resources, Ground Hazards

TerraDat uses state-of-the-art geophysical mapping techniques to map the subsurface. The benefit of geophysics is that it is non-invasive and can rapidly map large areas and reduce the chance of missing buried targets. We’ve been offering our services for over 25 years to clients from the engineering, environmental, energy and construction markets. Here are four case study booklets showing how geophysics can be applied to your ground investigations.

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Brownfield Site Investigation using Geophysics

Recent Surveys include: