A Practical Guide to Geotechnical Report Review - Nathan McNallie

Reducing Risk, Controlling Cost, and Improving Constructability
By Nathan McNallie | MCS Geotechnical Engineering

Abstract

Geotechnical reports play a critical role in construction projects, but they are often underutilized or misinterpreted. This disconnect can lead to unnecessary costs, delays, and avoidable risk.

This guide outlines a practical approach to reviewing geotechnical reports with a focus on real-world construction application. The goal is simple: improve decision-making, reduce risk, and control project costs.

Introduction

Geotechnical reports are intended to guide foundation design, earthwork operations, and site development. In reality, they are often treated as static documents rather than tools that should be actively interpreted.

Many project teams rely on recommendations without fully understanding the assumptions behind them or how they impact construction. This can lead to overly conservative decisions, missed cost-saving opportunities, and avoidable complications in the field.

MCS focuses on bridging that gap by applying practical, construction-focused interpretation to geotechnical data.

Where Geotechnical Reports Fall Short

Most geotechnical reports are technically sound, but they are not always optimized for construction efficiency. A common issue is the use of conservative assumptions. While these are often justified from an engineering standpoint, they can result in oversized foundations, excessive undercut requirements, and higher overall project costs.

Another frequent challenge is constructability. Recommendations are not always written with field execution in mind. This can create disconnects between design intent and what is actually feasible on-site.

Ambiguity also plays a role. Language that leaves room for interpretation can lead to inconsistent decisions during construction, especially when multiple parties are involved.

Finally, geotechnical recommendations are not always fully integrated into project plans and specifications. When this happens, the likelihood of RFIs, delays, and change orders increases.

Why This Matters on Real Projects

These issues have real consequences. Projects can experience cost overruns due to conservative designs or unnecessary work. Schedules can be impacted by unexpected soil conditions or unclear direction. Disputes can arise when expectations are not aligned between the design team and the contractor.

In many cases, the problem is not the data itself. It is the lack of a clear, practical review process.

How to Review a Geotechnical Report (Practical Approach)

A structured review can significantly improve outcomes. The first step is understanding the subsurface conditions. This includes reviewing boring locations, soil variability across the site, and groundwater conditions. These factors often have a direct impact on construction methods and cost.

Foundation recommendations should then be evaluated in context. It is important to understand how bearing capacities were determined and whether conservative assumptions were applied. In some cases, alternative approaches may provide the same performance at a lower cost.

Earthwork recommendations are another key area. Stripping depths, undercut criteria, and soil reuse potential should all be reviewed carefully. Small adjustments in these areas can have a large financial impact.

Pavement design should also be considered, particularly in relation to subgrade conditions and moisture sensitivity. Finally, potential risks such as soft soils, expansive materials, or groundwater should be clearly identified and tied to their impact on construction.

MCS applies this type of structured review to help ensure that geotechnical recommendations align with real-world project conditions.

Impact on Cost and Construction

Geotechnical decisions influence major cost drivers on a project. Excavation quantities, material import and export, foundation selection, and construction duration are all affected.

Even small changes in assumptions can result in significant cost differences. For example, adjusting an undercut depth or refining a bearing capacity value can reduce unnecessary work without compromising performance.

Opportunities for Value Engineering

A detailed review often reveals opportunities to reduce cost while maintaining performance. In some cases, undercut depths can be reduced. In others, foundation designs can be optimized or on-site soils can be reused more effectively.

These adjustments must be made carefully, but when done correctly, they provide meaningful savings without increasing risk.

Representative Scenario

On a commercial project, a geotechnical report recommended a uniform undercut across the building footprint. A closer review showed that soil conditions varied across the site. Instead of applying a blanket approach, undercutting was limited to only the areas that required it.

The result was a reduction in excavation quantities and material costs, while still maintaining the required performance of the foundation system.

This type of outcome highlights the value of project-specific interpretation.

Conclusion

Geotechnical reports are essential, but their value depends on how they are used. A practical, structured review process helps ensure that recommendations are applied correctly and efficiently.

MCS provides independent geotechnical review services focused on reducing risk, improving constructability, and controlling construction costs.

About the Author

Nathan McNallie is a senior geotechnical consultant with experience in construction materials testing, report review, and construction advisory services. He specializes in identifying risk, improving constructability, and providing practical recommendations for foundation and earthwork design.