Ground Improvement Verification Checklist: CPT, SPT, Plate Load

Definition: Ground improvement verification checklist guides contractors and QA teams to verify post-treatment performance using CPT, SPT, and plate load tests, compare outcomes to targets, and accept lots or trigger remediation.

Plan CPT, SPT, and plate load tests against approved targets.
Capture calibrated data with locations, depths, and time-stamped evidence.
Compare results to acceptance thresholds; decide accept, hold, or remediate.
Interactive, commentable, export, QR code for authenticated sign-off.

Start Interactive
Checklist

Ground improvement verification checklist helps field engineers and QA managers confirm that treated ground meets performance targets. This verification testing framework focuses on post-treatment validation using CPT, SPT, and plate load tests to demonstrate that deliverables align with approved project specifications and authority requirements. It excludes design and method selection, emphasizing practical acceptance testing, data integrity, and lot-based decisions. You will verify test equipment calibration, apply consistent procedures, and document results with traceable location data. By comparing measured qc, N60, and load–settlement responses against target envelopes, you can accept compliant areas or initiate remediation plans for underperforming lots. The checklist reduces risk of differential settlement, premature pavement distress, and bearing capacity underperformance by standardizing acceptance workflows and evidence capture. Use this interactive checklist to tick completion, add comments for nonconformances, and export as PDF/Excel with a QR-secured record.

Standardizes post-treatment verification using CPT, SPT, and plate load tests. Ensures calibrated instruments, consistent procedures, and traceable locations so acceptance decisions reflect true ground performance rather than sampling bias or operator variability.
Improves data quality and defensibility: records qc profiles, N60 corrections, and load–settlement curves with photos, calibration certificates, and survey files. Creates a transparent lot-by-lot acceptance matrix with clear pass/fail annotations and rationale.
Reduces risk of serviceability failures by detecting insufficient densification or stiffness early. Triggers targeted remediation steps and re-testing, preventing schedule surprises and costly rework during overlying pavement or foundation construction.
Interactive online checklist with tick, comment, and export features secured by QR code. Streamlines team reviews, digital signatures, and archiving, enabling rapid distribution to stakeholders and auditors without duplicating paperwork.

Pre-Test Administration

1. Confirm verification plan aligns with approved project specifications and authority requirements; list target qc, N60, and modulus values; record approval reference.
2. Check calibration certificates for CPT cones, pore-pressure sensors, SPT hammers, load cells, and dial gauges; certificates valid ≤ 6 months; photograph certificates.
3. Survey and stake test locations; capture coordinates (±0.5 m) and elevations (±10 mm); upload CSV and annotated plan showing lot boundaries.
4. Verify minimum waiting/curing period after improvement per project specifications; record completion dates and earliest test dates; obtain supervisor sign-off.
5. Establish access and safety controls: exclusion zones, stable platforms, lighting, and dewatering if needed; log toolbox talk and PPE compliance photos.

CPT Testing

6. Select cone (10 cm² or per plan) and saturate filter; zero sensors; record baseline; capture photo of setup and serial numbers.
7. Advance cone at 20 mm/s ± 5 mm/s; log qc, fs, and u2 every 10 mm; flag data gaps > 0.2 m.
8. Reach target depth (treated layer plus ≥ 1.0 m); document refusal criteria and actual termination depth; store depth vs resistance plot.
9. Perform repeat test at one location per lot; qc repeatability within ±10% over 1 m windows; investigate and recalibrate if exceeded.
10. Compare qc profile to target envelope per plan; mark segments pass/fail; attach annotated log and acceptance notes.

SPT Testing

11. Verify hammer mass 63.5 kg and 760 mm drop; document energy ratio from recent field check; note borehole diameter and rod length.
12. Drive split spoon after seating; record blows for three 150 mm intervals; compute N (last 300 mm); photograph blow count sheet.
13. Correct N to N60 for energy, overburden, borehole, and rod length; compare N60 to target values; attach calculations.
14. Backfill boreholes with suitable grout to surface; record volumes and batch details; dispose of cuttings per environmental plan.

Plate Load Testing

15. Select plate diameter per plan (typically 300–600 mm); verify load cell and gauges zero; photograph instrumentation and seating condition.
16. Prepare level test surface; apply seating stress 10–20 kPa; confirm settlement reset ≤ 0.5 mm before first increment.
17. Apply load increments to target stress; hold until settlement rate ≤ 0.1 mm/min or specified hold time; record settlement vs time both sides.
18. Calculate modulus and settlement at target stress; verify meets or exceeds project targets with no shear break; attach plots.

Data Review and Acceptance

19. Compile raw data, calibration files, survey coordinates, and photos; cross-check IDs to plan; note any missing or suspect data.
20. Populate lot matrix: CPT qc vs targets, SPT N60 vs targets, PLT modulus/settlement; annotate pass/fail and rationale for each test.
21. Issue lot acceptance if all tests meet targets; obtain digital signatures from contractor QA and client representative; attach QR-authenticated record.

Remediation Planning

22. Raise nonconformance for failed lots; describe deficiency (qc, N60, modulus shortfall); propose remedial method and re-test plan per approved specifications.
23. Implement hold points during remediation; re-test using same grid and methods; accept only when targets are met and evidence uploaded.

Scope, Sampling, and Lot-Based Strategy

This checklist covers verification only—confirming ground improvement outcomes using CPT, SPT, and plate load tests. It excludes design and treatment selection. Define lots by area or production sequence so acceptance reflects uniform treatment. Establish representative test spacing and depths that cover the treated layer and extend at least 1.0 m into underlying soils for control. Maintain consistent equipment, push/drive rates, and measurement intervals to limit variability. Record exact coordinates and elevations to tie results to the improvement layout. Evidence includes calibration certificates, photos, time-stamped logs, and survey files. The goal is to compare measured qc, N60, and load–settlement responses against target envelopes in the approved verification plan, then decide accept, hold, or remediate for each lot. This approach prevents isolated passes from masking weak zones and supports traceable, defensible sign-off decisions.

Define lots and representative test spacing before mobilization.
Test beyond treated depth by at least 1.0 m.
Standardize equipment settings and recording intervals.
Tie every result to surveyed coordinates and elevations.
Use targets from approved verification plan only.

Field Execution: Reliable CPT, SPT, and Plate Load Tests

Reliability depends on calibration, procedure control, and documentation. For CPT, maintain a steady 20 mm/s push rate and continuous logging at 10 mm intervals; verify repeatability within ±10% qc in at least one location per lot. For SPT, control hammer energy, record blows correctly, and compute N60 with corrections for energy, overburden, borehole, and rod length. For plate load tests, prepare a level surface, use appropriate plate diameter, and hold each increment until creep rates stabilize; plot load–settlement curves. Always photograph setups, gauges, and readouts, and record weather and groundwater conditions. If refusal or anomalies occur, document causes and adjust procedures (e.g., relocate slightly, pre-drill crusts) while staying within the approved plan.

Keep CPT push rate within 20 mm/s ± 5 mm/s.
Log CPT at 10 mm increments; avoid gaps > 0.2 m.
Compute SPT N60 with required corrections.
Stabilize plate load increments before readings.
Photograph setups, gauges, and results.

Acceptance Decisions, Records, and Remediation Triggers

After testing, compile data by lot and compare to target envelopes: qc profiles for CPT, corrected N60 for SPT, and modulus or settlement criteria for plate load tests. Annotate each test as pass or fail with clear reasoning. Accept lots only if all verification tests meet targets; otherwise, raise a nonconformance, outline deficiencies, and propose remediation actions per approved project specifications and authority requirements. Common remedial options include additional compaction passes, targeted grouting, or repeat vibro-treatment. Establish hold points and re-testing frequency to confirm improvement. Produce a concise report with plots, tabulated results, signatures, and a QR-secured export to support audits and archiving.

Use lot-based acceptance with clear pass/fail notes.
Escalate nonconformances immediately when targets are missed.
Define remediation scope and re-test plan.
Obtain digital signatures for acceptance.
Archive with QR-authenticated exports.

How to Use This Interactive Verification Checklist

Preparation: Gather the approved verification plan, calibration certificates, survey equipment, CPT rig, SPT tools, plate load kit, PPE, and ensure access, safety controls, and curing periods are satisfied.
Start Interactive Checklist: Open on a tablet, select lot ID, enable tick mode, and preload test locations from the survey CSV for traceable data capture.
Capture Evidence: Attach photos, instrument serials, data logs, and coordinates to each item; add comments for anomalies, refusals, or deviations with proposed corrective actions.
Review Against Targets: Use the acceptance matrix to compare qc, N60, and load–settlement to target envelopes; mark pass/fail per test and per lot.
Sign-Off: Apply digital signatures from contractor QA and client representative; generate a QR-authenticated link for the accepted lot records.
Export and Archive: Export the completed, commentable checklist as PDF/Excel; distribute to stakeholders and archive with project document control.

Call to Action

Jack yung Jack Yung

Dec 22, 2025

FAQ

Question: How many CPT, SPT, and plate load tests should I perform per lot?

Use the approved verification plan to set test frequency based on lot size, variability, and risk. As a guide, ensure enough tests to represent the full treated area and depth, including at least one repeat CPT for quality control. Always extend tests beyond the treated layer to verify underlying conditions and avoid biased acceptance.

Question: What if the CPT encounters refusal or erratic readings within the treated depth?

Document the depth, cause, and setup. Check filter saturation, push rate, and alignment. If obstruction or crust causes refusal, relocate slightly within the grid or pre-drill to the start depth if allowed by the plan. Record any change, maintain traceability, and ensure that acceptance still reflects target coverage before deciding pass/fail.

Question: How do I reconcile differences between CPT qc and SPT N60 results?

First, confirm calibration, energy corrections, and procedures. Compare both datasets to their respective target envelopes rather than to each other. If differences persist, review soil stratigraphy, groundwater, and variability within the lot. Prioritize the method specified for acceptance in the plan and consider additional confirmatory tests before remediation.

Question: When is a plate load test most useful for ground improvement verification?

Plate load tests are valuable when you need direct stiffness and settlement behavior under a representative stress, especially for slabs, pavements, or shallow foundations. Use plate sizes and stress levels per the plan, ensure stable readings at each increment, and compare calculated modulus or settlement to the specified targets for acceptance.