Index > 3 Characterisation of radioactively contaminated sites >

3.7 Site characterisation: Intrusive methods

Intrusive investigations are carried out to characterise sub-surface materials in order to obtain information on contaminant distribution and on the geological and hydro-geological environment. In addition, sub-surface investigations may be used to collect samples for geotechnical testing. Geotechnical sampling and testing is beyond the scope of this guidance document, although limited mention is made later in this section.

Sample material retrieved from intrusive investigations should be regarded as a resource for other phases in the project. Later stages of the EURSSEM process such as options comparison may need samples for small scale pilot testing of remediation methods. Geotechnical studies for subsequent new build may also require samples.

The cost and benefit of storage of retrieved samples and their preservation should be considered against the resources to obtain intrusive investigation samples in the future.
Intrusive investigations divide into three main aspects:

  • Health and safety.
  • Techniques.
  • Sample collection.

Samples collected during the site characterisation will be of the following types:

  • Soils and rocks. Soil samples are collected either manually, by hand-digging or by using an auger, or mechanically, using an excavator (for trial pits), window sampler, cone penetrometer (CPT) or drilling rig (for boreholes).
  • Surface waters and groundwaters. Groundwater samples are generally collected from boreholes that are either temporarily or permanently cased, or on occasion from trial pits.
  • Soil gases. Gas samples are generally collected from temporary shallow probes or from boreholes completed as ground gas monitoring points.

Safe digging practices is an important safety issue by intrusive investigations, therefore this aspect is dealt with in Section 3.7.2, Safe digging practices.