CPT and seismic CPT, done right.

Why CPT dominates reclamation QC

• Continuous profile with depth — no sampling gaps, no recovery questions.
• Direct measurement of tip resistance, sleeve friction and pore pressure.
• Fast turnaround that matches the pace of hydraulic fill placement.
• Verification of ground improvement at the scale of the treated area, not the borehole.

Execution is where data dies

A cone test is only as good as the push. Rate control at the standard 20 mm/s, correct zeroing and compensation, pore pressure behaviour read correctly, rod friction identified rather than ignored, and dissipation tests where drainage conditions matter. We run campaigns — and we have seen what bad execution does to a verification grid.

Interpretation is where correlations fail

Soil behaviour type classification, normalisation of qc, and the correlation between tip resistance and relative density are all built largely on silica sands. On carbonate and pumice sands, those correlations mislead: crushable grains can give deceptively high tip resistances with lower-than-expected stiffness. Relative density and liquefaction evaluation in carbonate reclamation fill is a calibration exercise, not a lookup — and calibrating interpretation against laboratory testing and field performance is a specialist job. It is exactly where standard practice falls over.

Seismic CPT and liquefaction

Adding shear wave velocity measurement to the CPT gives the Vs profile needed for liquefaction assessment of reclaimed land — the same push, one extra measurement, significantly better answers for seismic design. Combined with relative density evaluation in reclamation fill, this is the standard toolchain for proving a fill is non-liquefiable. See reclamation engineering services for seismic design capability.

Beyond the cone: the wider in-situ toolkit

For the measurements a cone can't give — undrained strength in soft clay, permeability, surface stiffness — we use in-situ field vane, permeability and plate load testing. Paired with CPT and seismic CPT, it gives a verification story no single test can.

QA/QC of the campaign itself

• Verification grids designed against the specification and the method of treatment.
• Acceptance criteria that reflect actual soil behaviour — not a generic qc threshold.
• Independent review of contractor CPT data before it becomes acceptance.
• Data managed and delivered in AGS format — the industry's electronic interchange standard — structured so it stands up to audit and feeds the project model without rework.
• Documentation that survives the inevitable scrutiny of a reclamation claim.