Independent geotechnical peer review is most useful when a project needs more than another set of comments. Its purpose is to test whether the ground model, assumptions, analysis and proposed solution are sufficiently robust for the decision being made.
That distinction matters. A review that focuses on formatting, preferences or minor technical differences can consume time without materially reducing risk. A useful review concentrates on the assumptions that control performance, the uncertainty that remains and the consequences if the project behaves differently than expected.
This article provides a practical framework for deciding when independent geotechnical review is justified, what the reviewer should examine and how owners, contractors and engineering teams can structure the process so it improves decisions rather than simply adds another approval layer.
Peer review should be driven by consequence, uncertainty and complexity
Not every geotechnical deliverable needs an independent peer review. Routine work with familiar ground conditions, well-established methods and limited consequence may be adequately controlled through the designer’s internal quality process.
Independent review becomes more valuable as three things increase: consequence, uncertainty and complexity. The interaction between those factors matters more than any one of them in isolation.
A technically simple foundation may justify independent review if it supports a highly sensitive facility. Conversely, a sophisticated numerical model may need only a focused review if the consequence is modest and the result is not governing. The review level should therefore be proportionate to the decision.
Start with the decision that needs assurance
The most effective peer reviews begin by defining the decision that the review is intended to support. That may be approval of a design basis, selection of a foundation concept, acceptance of excavation movements, release of a construction stage, evaluation of a bid assumption or confirmation that an observed response remains acceptable.
Without that definition, the reviewer is often given a large document package and asked to “review everything.” The result can be a long comment log where critical issues and low-impact preferences receive similar attention.
A better scope asks:
- Which assumptions would materially change the design if they are wrong?
- What performance mechanism governs the decision?
- What level of uncertainty is acceptable at this project stage?
- What evidence is needed before the team can proceed?
- Which aspects remain the responsibility of the designer, contractor, owner or temporary-works engineer?
What should an independent geotechnical reviewer trace?
A meaningful review should follow the engineering logic from the available evidence to the final decision. It should not begin and end with a calculation check.
Ground model and investigation coverage
The reviewer should first ask whether the investigation supports the design problem. That includes the number, depth and location of boreholes or CPTs; the quality of sampling and laboratory testing; interpretation of stratigraphy; groundwater conditions; variability across the site; and any gaps that are important to the governing mechanism.
A technically sophisticated analysis cannot compensate for a ground model that does not represent the site.
Parameter selection
Parameters should be consistent with the available data, stress history, drainage condition and strain level relevant to the problem. The reviewer should distinguish measured values from correlations and assumptions, and understand how uncertainty has been carried through the analysis.
Design basis and loading
The review should confirm that the analysis represents the appropriate geometry, loading, groundwater scenarios, construction stages, temporary conditions, seismic demands and acceptance criteria. Important interfaces with structural, civil and temporary-works design should be explicit.
Analytical method
The chosen method should be proportionate to the decision. Simplified calculations may be entirely appropriate for some problems. Others may require consolidation analysis, soil–structure interaction, staged finite-element modelling or dynamic assessment.
The reviewer’s role is not to demand a more complicated method automatically. It is to determine whether the method captures the mechanism that controls the decision.
Sensitivity and robustness
Where uncertainty is meaningful, the review should test whether the conclusion changes within credible ranges of soil properties, groundwater, stiffness, strength, loading or construction sequence. A design that works only for one narrow combination of assumptions deserves more attention than one that remains acceptable across a reasonable range.
Constructability and temporary conditions
Many geotechnical problems are controlled during construction rather than in the final condition. Excavation stages, dewatering, temporary slopes, support installation, preload, pile installation, ground improvement sequencing and access can materially alter ground response. A review that examines only the final design may therefore miss the critical stage.
Monitoring and observational controls
If uncertainty remains during construction, the reviewer should consider whether the monitoring plan, baseline, trigger levels and response actions are sufficient to detect adverse behaviour early enough for the project to act.
When advanced numerical modelling is involved
Independent review becomes especially valuable when a decision relies heavily on advanced numerical modelling because a model can appear precise even when the controlling uncertainty sits in the assumptions rather than the calculation.
A reviewer should therefore look beyond contour plots and headline displacements. The review should examine constitutive models, parameter derivation, boundary conditions, initial stresses, groundwater, interfaces, staged construction, sensitivity, calibration and whether the predicted mechanism is physically credible.
Our related insight, When Does a Geotechnical Problem Need Advanced Numerical Modelling?, discusses how the decision should determine model complexity rather than the other way around.
Peer review during design-build pursuits and preconstruction
Independent review can add value well before final design. During a pursuit or preconstruction phase, the largest geotechnical risks may be embedded in assumptions that influence pricing, schedule, construction sequence or risk allocation.
A focused review can test whether:
- the available geotechnical information supports the proposed construction approach;
- foundation or excavation assumptions are overly optimistic or unnecessarily conservative;
- an alternate solution has a credible technical basis;
- groundwater or settlement risks have been adequately priced and scheduled;
- the design concept is compatible with likely means and methods; and
- the bid relies on unresolved assumptions that should be identified before commitment.
At this stage, the value of review may come less from checking calculations and more from exposing assumptions that could later become commercial or construction risk.
Peer review during construction
Construction-stage review is different. The question is often no longer “Is the design reasonable?” but “What does the observed behaviour mean, and what decision should the team make now?”
Examples include unexpected soil conditions, excavation movement, pile refusal, settlement, groundwater inflow, instrumentation trends or a proposed field change. The reviewer may need to compare observed conditions with the original design assumptions, identify the likely mechanism and help define whether additional analysis, monitoring, mitigation or a hold point is appropriate.
The review must remain disciplined about roles. Independent advice should not blur responsibility for design, construction means and methods, safety or contract administration.
What makes a peer review effective?
The quality of the review is not measured by the number of comments. It is measured by whether the important technical risks are identified, tested and resolved in time to influence the project.
- Risk-based and focused on material issues.
- Independent challenge of assumptions, methods and governing results.
- Targeted checks where they test robustness.
- Constructive technical dialogue and clear issue closure.
- Recommendations linked to decisions, actions and residual uncertainty.
- Long lists of minor or stylistic comments.
- Duplicates the original design rather than reviewing it.
- Creates ambiguity about responsibility.
- Starts too late to influence major decisions.
- Ends with unclear conclusions or no resolution path.
Prioritize comments by significance
Critical issues that could affect safety, performance or major project decisions should be distinguished from lower-impact recommendations. This allows the design team and decision-makers to focus effort where it matters.
Resolve issues through technical dialogue
A focused technical workshop can often resolve more than several cycles of written comments, particularly where the disagreement is about assumptions, interpretation or project context.
Use independent checks selectively
The reviewer does not need to reproduce the entire design. Targeted calculations, alternate parameter cases or simplified checks are often more valuable because they test whether the original conclusion is robust.
Document closure
The final review record should show how material issues were addressed, what remains open and what assumptions or conditions the conclusion depends on.
When peer review may not be warranted
Independent review is not automatically beneficial. It may add little value when the work is routine, the consequence is low, the design approach is well established and a competent internal checking process already provides sufficient assurance.
It can also become inefficient when the scope is undefined, the reviewer is engaged too late to influence the decision or the process becomes a second design rather than an independent challenge.
The objective is therefore not “more review.” It is the right level of independent challenge at the point where it can still improve the outcome.
Questions to ask before commissioning a review
A clear scope and terms of reference are essential. Before engaging an independent reviewer, the project team should be able to answer:
- What decision needs additional assurance?
- What is the consequence if the governing assumption is wrong?
- Where is the principal uncertainty?
- What is explicitly inside—and outside—the review scope?
- At what project stages should the reviewer be engaged?
- What documents, data and calculations are available?
- What outcome is needed: comment log, workshop, technical memorandum, assurance statement or ongoing review?
Independent review should improve confidence, not create bureaucracy
The best geotechnical peer review is not measured by the number of comments it generates. It is measured by whether the project has greater confidence that the important ground risks have been understood, the governing assumptions have been tested and the proposed decision is technically defensible.
For complex projects, that may require a comprehensive independent review. For others, a short second opinion on one critical assumption may be enough. The review should remain proportionate to the uncertainty, consequence and decision at hand.
Geotechnics Plus provides independent geotechnical peer review and technical assurance for owners, contractors and engineering teams that need focused senior technical challenge on complex ground decisions.
References and further reading
The following sources provide broader context on geotechnical practice, peer review, uncertainty and risk management. They do not prescribe a single universal trigger for peer review; project-specific requirements and applicable codes, contracts and regulations still govern.
- Canadian Geotechnical Society. Canadian Foundation Engineering Manual, 4th Edition, 1st printing 2006. CGS errata and edition record.
- Federal Highway Administration. Soils and Foundations, Volume I, FHWA NHI-06-088, 2006. The guidance emphasizes experienced geotechnical judgment and recommends peer review of subsurface models on appropriate projects. FHWA publication.
- International Organization for Standardization. ISO 31000:2018 — Risk management — Guidelines. ISO 31000.
- Phoon, K.-K. and Ching, J. (eds.). Risk and Reliability in Geotechnical Engineering. CRC Press, 2015. Publisher reference.