Developers and earthworks contractors constantly require Geotechnical Certification and Site Classification as part subdivision development. Often, as site works progress, additional issues arise that require further geotechnical input.

The site occupies a parcel of land located on Coast Road, Bennett Springs. The ground conditions at the site generally comprised topsoil, overlying Bassendean Sand, overlying Sandy Clay/Clayey Sand of the Guildford Formation. 


  • Topsoil strip assessment and verification.
  • Proof compaction assessment and verification.
  • Identification of uncontrolled fill, assessment and verification of uncontrolled fill excavation/removal.
  • Perth Sand Penetrometer audit testing for bulk and civil earthworks to verify compaction and for comparison with the Earthworks Contractor’s compaction records.
  • Assessment of site classification in accordance with AS2870-2011.
  • Recommendations to improve a ‘Class P’ portion of the site to ‘Class A’.
  • Assessment of the suitability of excavated material for reuse as structural fill.
  • Placement and compaction recommendations for site won material and imported granular fill material.

Key Challenges and Solutions

Due to the timing requirements of the client, a portion of the work required immediate geotechnical investigation and assessment for foundations associated with a 200m long gravity, noise wall. We recommended and completed a total of 8 CPTs along the proposed wall alignment. We then provided earthworks preparation recommendations, allowable bearing pressures and estimated settlements for the retaining wall. This work was completed and the advice issued within three days of the request.