New Construction vs. Forensic Geotechnical Investigations — Which One Do You Need?
Choosing the Right Investigation for Your Project Stage
Introduction
At Sandia Geotechnical Services (Sandia GEO), we’re often asked: Do I need a geotechnical investigation before I build — or only if something goes wrong?
Whether you're breaking ground on a new structure or trying to understand why an existing one is failing, choosing the right type of geotechnical investigation is critical. Here’s how to tell the difference — and why it matters.
New Construction Geotechnical Investigations
Build on Certainty from the Start
A new construction geotechnical investigation is a proactive study of subsurface soil and rock conditions. It’s designed to inform foundation design, identify geotechnical hazards, and ensure long-term structural stability.
At Sandia GEO, we conduct these investigations to help engineers:
Determine soil bearing capacity and settlement potential
Identify expansive soils, groundwater issues, or other site-specific risks
Comply with regulatory requirements and avoid costly delays
Design foundations that perform reliably over time
Typical Cost Range: $5,000–$20,000
Cost Drivers:
Site accessibility
Number of boreholes
Types of tests (e.g., SPT, lab analysis)
These investigations follow a planned schedule and offer predictable costs — making them a smart investment in risk prevention.
Forensic Geotechnical Investigations
When You Need to Know What Went Wrong
A forensic geotechnical investigation is a reactive, in-depth analysis performed after a structural issue has occurred. It’s designed to uncover the root cause of failure — whether it’s settlement, slope instability, or construction-related disputes.
Sandia GEO’s forensic investigations combine fieldwork, lab testing, historical data review, and expert analysis to answer questions like:
Why did this foundation fail?
Was the soil properly evaluated before construction?
Are there underlying geotechnical conditions that were missed?
Typical Cost Range: $10,000–$50,000+
Cost Drivers:
Depth and complexity of analysis
Advanced testing methods (e.g., geophysical surveys)
Multidisciplinary involvement (e.g., structural engineers, legal experts)
These investigations often involve tight deadlines, legal consultation, and the potential for expert testimony — all of which can drive up costs.
Comparison Table
| Factor | New Construction Investigation | Forensic Investigation |
|---|---|---|
| Purpose | Prevent issues before construction | Diagnose issues after failure |
| Timing | Planned and scheduled | Reactive and often urgent |
| Cost Range | $5,000–$20,000 | $10,000–$50,000+ |
| Testing Scope | Standardized, design-focused | Extensive, failure-focused |
| Legal Involvement | Rare | Common, especially in litigation |
| Remediation Potential | Preventative | May require costly retrofitting |
Straightforward Advice from a Trusted Team
At Sandia GEO, we don’t oversell or overcomplicate. Whether you’re planning a new build or investigating a failure, we provide clear, unbiased assessments backed by over 25 years of experience in New Mexico and Arizona soils.
We’ll help you determine the right investigation for your needs — and deliver the data you need to move forward with confidence.
Contact Us to schedule a consultation or site assessment.
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Helpful External Resource
For engineers seeking technical standards, the ASTM D420 – Guide to Site Characterization for Engineering Design and Construction offers a useful framework for geotechnical investigations.