Geotechnical Assessments

We can undertake geotechnical and geo-environmental assessments of your development site to examine near surface soil properties for foundation, highway pavement and retaining wall design.We can also assess contamination to address legacy land uses.


Contaminated land assessments start with a Phase 1 Preliminary Risk Assessment (PRA) to determine the likelihood of contamination. The PRA is then used to determine the extent of works required for the Phase 2 intrusive investigation. During Phase 2 samples are taken and tested for contaminants. Phase 3 works are for Remediation proposals and Validation of the remedial works.

Geotechnical Services:

  • Preliminary Risk Assessment
  • Phase 2 Intrusive Contamination Investigation
  • Phase 3 Remediation and Validation
  • Geotechnical Investigation, trial holes and boreholes
  • Recommendations for foundation design
  • 2323kg/m3

    Is the density of sandstone

    Phase 1: Preliminary Risk Assessment

    Evidence gathered from site walkovers
    This will involve a thorough investigation into current and previous land uses. We use available information including historical maps, local government resources and local knowledge to identify potential sources of contamination on the site.

    Aspects that may affect the site, including coal mining, brine subsidence and landfill are identified in this report. Existing services, such as gas and electricity that may be affected by site development are also considered, if required.

    Phase 2: Contaminated Land Investigation

    A Phase 2 investigation determines the nature and extent of contamination present on a site. This is done through intrusive investigation and sampling techniques selected specifically for the identified site conditions.

    Soil and water samples are analysed by approved laboratories. The results are then used to assess risk, toxicology and necessary remediation methods. A remediation strategy is devised, based on the proposed land use and receptors. All proposed ground investigations, soil/water testing and remediation proposals must be discussed and agreed with the local authority at each stage.

    Phase 3: Remediation and Validation

    Throughout the remediation, regular monitoring is conducted to ensure the works comply with the approved remediation strategy.

    Imported or recycled material is tested to ensure suitability for its intended use, whether as fill or as part of an engineered remediation design. A validation report includes testing of remediated areas and evidence of disposal of waste to ensure the site is fit for its intended use.

    Other environmental services provided by Thomas Consulting include landfill leachate monitoring, gas, water and soil testing and waste disposal advice.