5 Geotechnical Red Flags That Will Cost Contractors Money on a Job
What to Look For in a Geotechnical Report Before It Impacts Cost and Schedule
By Nathan McNallie/MCS Geotechnical Engineering
Introduction
Most geotechnical reports don’t look like they’ll cost you money.
They’re organized, technical, and full of recommendations that seem straightforward. But buried in those details are assumptions and conditions that can quietly drive cost, delay schedules, and create problems once construction starts.
The issue is rarely that the report is “wrong.”
More often, it’s how certain conditions are interpreted—or not fully understood—before the work begins.
Here are five red flags worth paying attention to.
1. Wide Boring Spacing (Limited Data)
Borings are not a complete picture of a site—they’re sample points.
If those points are spaced far apart, you’re relying on interpretation between them. Soil conditions can change quickly, even over short distances.
Why it matters:
Unexpected undercut
Unplanned stabilization
Delays while conditions are re-evaluated
What to look for:
Large gaps between boring locations
Different soil profiles from one boring to the next
2. “Suitable Soils” Without Clear Criteria
“Suitable soils” sounds straightforward, but it often isn’t defined clearly.
Suitability can depend on:
moisture content
compaction
gradation
field conditions at the time of construction
Why it matters:
Disagreements in the field
Over-excavation to “be safe”
Rework when assumptions don’t hold
What to look for:
Vague language without measurable acceptance criteria
3. Groundwater Not Fully Addressed
Reports often note groundwater, but not always how it behaves.
Conditions can change with:
weather
excavation depth
drainage and site disturbance
Why it matters:
Dewatering requirements
Slower production
Subgrade instability
What to look for:
“Groundwater not encountered at time of drilling”
Limited discussion of seasonal variation
4. Uniform Recommendations Across the Site
When one recommendation is applied everywhere, it may be simplifying real variability.
Most sites don’t behave uniformly.
Why it matters:
Treating good soil like bad soil
Missing localized issues
Overbuilding or under-preparing
What to look for:
Single bearing values or undercut depths applied site-wide
5. Conservative Recommendations Without Context
Conservative design is often appropriate—but without context, it can drive unnecessary cost.
Some recommendations are written for worst-case conditions without distinguishing what’s typical.
Why it matters:
Larger foundations than needed
Excessive undercut or stabilization
Increased material and labor costs
What to look for:
No explanation of variability or confidence level
No distinction between typical vs. worst-case conditions
Conclusion
Geotechnical reports are not the problem—misinterpretation is.
Most cost impacts come from:
assumptions being treated as guarantees
variability being overlooked
conservative recommendations applied without context
Catching these red flags early doesn’t eliminate risk, but it allows for better planning, clearer expectations, and fewer surprises once construction begins.
About MCS Geotechnical Engineering
MCS Geotechnical Engineering provides independent consulting focused on geotechnical report review, risk identification, and construction-phase advisory. The goal is simple: translate subsurface information into practical, buildable decisions that reduce risk and control cost.
