Stop Treating Geotech Reports Like the Final Word on Helical Piles
Introduction: A Familiar Breakdown
"A 5.5” (140 mm) helical pile with two 16” diameter (406mm) helices can support up to 60 kips (266 kN) ULS at approximately 40' (10m) depth."
That’s the kind of line you’ll find in many geotechnical reports. It’s not a design. It’s not a mandate. It’s a starting point - a baseline intended to inform, not prescribe.
But too often, that nuance gets lost.
By the time the pile designer sees the final structural foundation plans, the layout is fixed, the loads are locked in, and the opportunity for optimization has mostly vanished. Everyone followed the steps, but nobody had the conversation.
And it shows: oversized rigs, overly conservative designs, and pile plans that don’t reflect what the project really needs.
This article is about stopping that cycle. It’s about giving engineers and builders the clarity to collaborate earlier, question assumptions, and ultimately build better foundations - together.
Why This Happens: The Context Disconnect
Each discipline is working with a different piece of the puzzle.
Geotechnical engineers are usually engaged early, often before architectural or structural designs are underway or even finalized. They investigate the soil and offer key observations about suitable foundation options. If helicals are feasible, they may include sample configurations to demonstrate capacity ranges in relevant strata.
Structural engineers, trying to keep the project moving, lean on the geotech report as a reference. They see a configuration that supports up to 60 kips (266 kN) and start laying out piles based on that capacity, believing they’re staying within the geotechnical envelope.
Pile designers and contractors are then brought in - sometimes post-permit, often during tender - and are handed a design already locked into assumed layouts, loads, and pile types. There is little room to suggest alternatives without triggering redesigns or delays.
No one did anything wrong. But the process failed. Assumptions built on assumptions, without validation or dialogue.
The Real Consequences: Overdesign and Inefficiency
When we treat preliminary guidance as a final directive:
Overbuilt Foundations - Fewer piles with higher torque and longer lengths drive up costs and equipment demands.
Reduced Flexibility - Once structural drawings are finalized, changes trigger ripple-effect redesigns.
Costlier Mobilization - Larger piles require specialty rigs. Slight increases in pile count could yield big equipment savings - if considered early.
Delayed Optimization - The opportunity to improve the design is missed until construction - where changes are costly.
This isn’t just technical inefficiency - it’s a missed opportunity for collaboration and cost control.
What a Geotech Report Is (and Isn’t)
What it is:
Subsurface soil and bedrock profiles: Including borehole logs, test pit descriptions, and relevant site geology.
Groundwater conditions: Seasonal levels, perched water tables, and long-term observations if available.
In-situ and laboratory testing data (if samples are taken): SPT, CPT, vane shear, grain size, consolidation, etc.
Bearing capacity estimates: For shallow and deep foundations, often in terms of factored resistance.
Settlement analysis: Both immediate and long-term estimates, including total and differential settlement.
Lateral resistance parameters: Including modulus of subgrade reaction, friction angles, and passive resistance.
Frost considerations: Including frost penetration depth and frost susceptibility of soils.
Seismic site classification – Per IBC, NBCC or other relevant codes.
Corrosion and aggressivity data (when requested): Sulfate content, pH, resistivity for evaluating foundation durability.
Preliminary foundation recommendations: Including viable foundation systems like spread footings, piles (including helicals), and slabs-on-grade.
Limitations and assumptions: Explicitly stating the scope, timing, and intended use of the report.
What it isn’t:
A finalized structural foundation plan
A specification for pile type or layout
A precise directive for manufacturer or installation method
So when a report states:
"A 5.5" pile with a double 16" helix can provide up to 60 kips (266 kN) ULS at 40' (~12m) depth"
It generally means: This is what's possible and reasonably achievable. Now coordinate.
Advice for Structural Engineers: Don’t Take It Literally
You don’t need to be a pile expert. But knowing when to ask questions? That’s what separates good from great.
Talk to a pile designer before finalizing layouts.
Share actual loads, geometry, and constraints.
Ask: "If our max load is 35kip (~155kN) , could a smaller shaft or shallower depth work better?"
Don’t assume bigger is better. Optimization means right-sizing for buildability, cost, and context.
Advice for Geotechnical Engineers: Frame It Clearly
You already know your pile suggestion will work, but you also know they are simply a few of many available options and configurations. These sections in your reports are meant to demonstrate feasibility, and provide context of what's possible, not to dictate or prescribe final solutions. But downstream most readers do not interpret them that way.
A few simple shifts in how recommendations are presented can encourage better coordination:
Use clear language Replace definitive phrases with collaborative ones like: “Suggested configuration,” “indicative capacity range,” or “preliminary resistance estimate.”
Offer a range of values Instead of: “A 5.5 in (140 mm) shaft with double 16 inch (406 mm) helices can support up to 60 kips (266 kN) ULS,” try: “Typical helical piles in this range may achieve factored resistances of 20 to 60 kips (90 to 266 kN), depending on embedment and installation conditions.”
Add a coordination note
Clarify the role of the report
This isn’t about legal disclaimers - it’s about enabling informed design and reinforcing your role as the ground-truth expert.
By clearly signaling that your pile size recommendations are starting points and not the only available options, you empower structural engineers to ask better questions, pile designers to optimize more effectively, and project teams to move forward with clarity and confidence.
Practical Alignment with Engineering Best Practices and Guidelines
Engineering regulating bodies emphasize two core professional obligations:
Work within your area of competence
Collaborate with other qualified professionals when appropriate
That’s not just legal language - it’s practical guidance that improves outcomes.
To support that, it’s essential to clearly define the unique (but interdependent) roles each discipline plays when designing with helical piles:
Geotechnical Engineers
Characterize subsurface conditions
Determine soil profiles, groundwater levels, and bearing capacity
Provide preliminary axial and lateral resistance values
Can offer torque-to-capacity correlations based on stratigraphy
Assess installation feasibility
Their role is to define what the ground will allow - not what the structure needs.
Structural Engineers
Define structural load paths (axial, lateral, uplift)
Determine footing sizes, column loads, and geometry
Specify pile layout, spacing, and required resistance
Their role is to determine what forces must be resisted - not how the pile system achieves it.
Geostructural Engineers / Helical Pile Designers
Integrate structural demands with soil behavior
Select optimal shaft size, helix configuration, and embedment
Model load-transfer mechanisms
Ensure constructability within site constraints
Provide final pile design, certified by a licensed engineer
Their role is to bridge geotechnical and structural insight - delivering a safe, efficient foundation system that works in the field.
Why It Matters: Respecting role boundaries isn’t about red tape - it’s about designing smarter. When each expert owns their piece of the puzzle and invites coordination, the results are not just code-compliant - they’re constructible, efficient, and reliable.
This is the model that engineers, clients, and builders should expect - and it’s how we elevate the profession.
A Better Workflow: What Good Collaboration Looks Like
Geotechnical Engineer confirms helical pile feasibility and soil compatibility, offering ranges.
Structural Engineer shares actual loads and geometry before pile layouts are locked in.
Geostructural Engineer (Pile Designer): reviews and proposes optimized configurations.
Structural adjusts drawings accordingly.
Everyone signs off early with confidence.
This doesn’t slow the project. It accelerates it - and saves real time and money.
Final Thoughts: We Build Better Together
If you’re a structural engineer, trust your instincts to ask questions. If you’re a geotechnical engineer, trust your influence to guide coordination.
And if you’re a project manager, consultant, or part of the design team, consider this: Most projects don’t bring in a geostructural engineer - or helical pile specialist - until it’s too late to optimize. They’re hired through the contractor after the design is already locked, the permit is issued, and the opportunity for value engineering is gone.
That’s the root of the problem.
The pile system gets assumed before it ever gets designed. The design gets priced before it ever gets challenged. And better solutions get left on the table - not because they didn’t exist, but because no one was in the room to share them.
This article isn’t just about raising awareness. It’s about offering a better process.
Bring geostructural insight in earlier. Loop in a pile designer during structural layout - not post-permit. Ask for input when it’s still easy to adapt. And create space for coordination between geotechnical, structural, and geostructural perspectives - before decisions are baked in.
No one wins when we build on assumptions. Everyone wins when we design with clarity, collaboration, and the right voices involved at the right time.
So next time you see a geotechnical report, don’t treat it like a rigid and final specification.
Treat it like what it was always meant to be: The start of a smarter conversation - with more people at the table.
