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3.4.11 Geological

Contents Geological logging Geotechnical tests Geological logging

All boreholes and trial pits should be logged. In addition, the following information should be recorded:

  • Depth and results of any in-situ radiological or chemical monitoring.
  • Depths and depth ranges and type of any samples collected for chemical or radiochemical analysis.
  • Depths of any man-made features. Geotechnical tests

In some circumstances it may be possible to combine a contaminated land survey with a geotechnical survey. Samples retrieved from all types of subsurface investigations should be regarded as a potential resource for other projects. However, a number of points should be borne in mind:

  • The quality of the contaminated land survey may be degraded if sampling locations are moved to provide the best location for geotechnical sampling (or vice versa).
  • The appropriate intrusive method for the contaminated land survey may not be appropriate for the geotechnical survey (or vice versa).
  • Samples must be tested for radioactive contamination prior to the geotechnical testing being carried out. This is required to establish any special health and safety measures that need to be undertaken.
  • Consideration should be given to the appropriate storage of materials retrieved for tests for other projects, such as remediation pilot trials.

Geotechnical testing methods are described in detail in [BSI-1990]. Some examples of common tests are given in Table 3.31.

In-situ tests Ex-situ tests
Standard penetration tests Liquid and plastic limit tests
In-situ California bearing ratio test Moisture content
Hand shear vane test Undrained triaxial compression tests
Perth penetrometer test California bearing ratio test
pH and sulphate testing

Note: Although pH and sulphate testing are chemical tests, they are included in the geotechnical suite as they are used to determine the potential for degradation of foundation to occur.

Table 3.31 Common in-situ and ex-situ tests