Soil boring logs are standardized records used by geotechnical engineers to document subsurface conditions encountered during drilling. They capture soil and rock descriptions, sample depths, groundwater observations, and in-situ test results that directly inform foundation design, earthwork planning, and construction risk management.
Accurate soil boring logs are critical because they influence safety, cost, and project timelines. Incomplete or inconsistent logs can lead to design errors, change orders, and delays, especially when field notes are recorded on paper or transferred manually into spreadsheets after drilling.
This guide explains what a soil boring log is, what information it should include, and how geotechnical engineers use boring logs to interpret subsurface conditions. It also shows how modern software like Aldoa helps teams create consistent, client-ready boring logs faster by connecting field and lab data in a single workflow.
A soil boring log is a record of subsurface conditions observed and sampled during drilling. It typically includes location and elevation, drilling method, sample intervals and recovery, blow counts, lithology, groundwater conditions, photos, and notes that together form a defensible profile for design.
.png?width=730&height=1000&name=A4%20-%20filled%20(4).png)
The right number depends on site size, variability, structure loads, and local guidance. For small facilities or infiltration practices, one to two explorations might suffice. As area and complexity grow, add locations to capture variability and confirm depth to bedrock and groundwater. A practical rule: increase spacing in uniform sites and tighten spacing in filled, urban, or geologically complex areas.
Tip: If you discover unexpected materials or refusal, add offset borings to reduce uncertainty.
Looking to digitize your boring logs? Modern geotechnical teams are replacing spreadsheets and legacy systems with structured logging workflows. See how it works in Aldoa: Schedule a demo.
| Method | Typical depth | Speed | What it is good for | Notes |
|---|---|---|---|---|
| Soil probe | ≤ 3 ft | Fast | Shallow profile checks | Limited data, not for design on its own |
| Hand or power auger | ≤ 50 ft | Moderate | Unconsolidated soils | No blow counts with hand auger |
| Test pits | ≤ 20 ft | Fast | Visual logging and bulk samples | Requires excavation equipment and safety controls |
| Direct Push (DPT) | 60–100+ ft | Fast | Continuous sampling with minimal cuttings | No SPT N-values |
| Rotosonic | 100+ ft | Fast | Continuous core through difficult formations | Mobilization costs can be higher |
| Hollow Stem Auger with SPT | 100+ ft | Moderate | Foundation investigations, infiltration decisions | Provides SPT N-values and flexible sampling |
Choose methods that match project goals. If you need blow counts for density or consistency, plan for SPT with hollow stem auger.
If possible, have a geotechnical engineer onsite during drilling to coordinate locations, adjust intervals when conditions change, and document observations. Clear instructions for drillers will improve outcomes:
A defensible log has consistent identifiers and complete metadata:
Understanding the theory behind soil boring logs is important. But reviewing a complete example is often the fastest way to improve interpretation skills and field documentation quality.
If you want to see how:
Review this soil boring log example (annotated) for a step-by-step breakdown of a real borehole log.
The example walks through each column of the log and explains how engineers interpret blow counts, stratigraphy, and groundwater in context. It also highlights common documentation mistakes that digital workflows help eliminate.
Studying a complete example alongside this guide will help you move from theory to practical application.
Pro tip: Use standard forms and controlled vocabulary for soil descriptions to keep logs consistent across crews and projects.
Restrictive layers such as dense clays, cemented zones, perched water, or bedrock limit infiltration and can cause perched groundwater. When interpreting logs:
Many geotechnical firms still create soil boring logs in:
This creates problems:
Modern soil boring log software eliminates these issues by structuring field data from the start.
Many firms historically used Bentley gINT for borehole logging. As legacy systems become unsupported or harder to maintain, geotechnical teams are moving toward cloud-based soil boring log software that connects field, lab, and reporting in one workflow.
If you're evaluating soil boring log software, prioritize:
.png?width=1954&height=1402&name=Group%2027379%20(1).png)
Aldoa replaces spreadsheets, shared drives, and legacy borehole logging tools with a single workflow:
Plan and dispatch: Create work orders, assign the right driller or technician, and attach maps and forms so crews know exactly what to collect.
Capture structured field data: Log sample intervals, recovery, and SPT N-values in structured forms. Attach photos and site notes. Initiate lab tests from the field to give the lab a head start.
Initiate lab tests instantly: Field crews trigger lab testing from the borehole record. The lab sees upcoming samples before delivery.
Connect lab results automatically: As tests are completed, results flow back into the boring log. No retyping.
Generate client ready reports:
All from a single source of truth.
👉 See how modern geotechnical teams digitize borehole logging. Schedule a demo.
Even experienced teams make mistakes that lead to rework:
Digital workflows reduce these risks by enforcing required fields, standard terminology, and real-time validation.
.svg "Aldoa Assets (3)")