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Published By Lankelma

Lankelma is the foremost contractor for onshore in-situ soil testing in the UK. An acknowledged specialist in CPT, Lankelma also offers a worldwide consultancy and training service.

A.P. van den Berg develops, designs and manufactures geotechnical and environmental soil investigation equipment for onshore and offshore applications. Specialists in CPT systems and equipment.


Gardline Geosciences offers worldwide marine geotechnics, in-house consutancy and services with marine investigations ranging from nearshore to full ocean depth (down to 3000m).

About the Author

Hans Brouwer studied civil engineering at Delft University in The Netherlands. He has worked as a part-time lecturer at Amsterdam Polytechnic and was senior partner in a structural engineering consultancy. He has written a standard textbook in Dutch about the design of building foundations. He now lives in England where he writes technical textbooks in English, hopefully to reach a bigger readership.

Chapter 4

Part 2: Special cones: geo-environmental cones

Environmental cone

Contaminated sites
The environmental cone (Figure 29) is designed for the investigation of contaminated sites. There are countless examples of areas with soil polluted with chemicals and oil to such an extent that it represents a direct danger to health.
Normally these probes are combined with a piezocone, measuring porewater pressure, sleeve friction and tip resistance. The environmental measurements of the groundwater are the acidity (pH), the oxygen exchange capacity (redox potential) and temperature with depth while being pushed into the soil. Measurement of the electric conductivity can also be incorporated. The parameters are major variables of chemical equilibrium for inorganic substances such as oil and chemicals.
The sensors are mounted inside the cone. A groundwater sample is
drawn into a measuring cell, located a short distance behind the cone tip.

Measurements are made under a nitrogen atmosphere to reduce the
exchange of atmospheric oxygen with dissolved gases from the
groundwater. A slight excess pressure of nitrogen is used during
penetration of the probe to stop the flow of liquid into the measuring
cell. The nitrogen is supplied from a small nitrogen cylinder in the
probe. The stainless steel porous filter is cleaned by the excess
A pressure sensor is also included to monitor the flow of liquid into the
measuring cell and to estimate the hydraulic conductivity of the
surrounding soil.
The measurements enable the detection of the magnitude and type of
pollution. In this way the method offers an objective choice of whether
or not further laboratory analysis is needed and is therefore secure,
timesaving and cost efficient.
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