---
title: "Borehole log format"
subject: "Foundation Engineering"
chapter: 2
key: "semester_5/foundation_engineering:borehole-log-format"
source: https://www.bctengineer.com/q/semester_5/foundation_engineering/borehole-log-format
site: BCT Engineering
---

# Borehole log format

Foundation Engineering · Chapter 2: Soil Exploration

- Asked in: 2080 Baisakh, 4 marks; 2075 Asoj, 3 marks (asked 2 times)
- Video: [How To Read Borehole Logs | What You Need to Know To Correctly Interpret Soil Data #education](https://www.youtube.com/watch?v=nNFpItYm3GE) — Soil Mechanics and Engineering Geology
- Answer checked by Claude Sonnet 5.5 on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/foundation_engineering/borehole-log-format
- Whole chapter: https://www.bctengineer.com/md/semester_5/foundation_engineering/chapter-2

## Question

Describe briefly the borehole log format with a suitable example.

## Short answer

A borehole log has a header with project, boring method, and groundwater level, plus columns for depth, soil description and graphic symbol, sample type, SPT N-values, and remarks. It records the vertical succession of strata, water table, and in-situ test results for foundation design.

## Answer

A **borehole log** is a graphical and written record of the soil encountered in one borehole against depth. It is prepared from field notes and laboratory results.

#### Information in the header
- Project name, location, client, borehole number and coordinates/reference level.
- Method of boring, diameter, date started and completed, driller/engineer.
- Groundwater level (date of observation).

#### Columns of the log
| Depth (m) | Soil description / symbol | Sample type and depth | SPT N | Remarks |
|---|---|---|---|---|

- **Depth/RL scale** and thickness of each layer.
- **Graphic legend** (hatch symbols) and **soil description** with IS classification (colour, consistency/density, grain size).
- **Sample type** (disturbed D, undisturbed U, SPT) and depths.
- **SPT N-value** (and optionally core recovery, RQD for rock).
- **Water table** and any seepage, loss of drilling water, cavity or boulders.
- **Remarks** such as refusal and end of hole.

#### Example (BH-1, RL 100.00 m, GWT 2.0 m)
| Depth (m) | Description | Sample | N |
|---|---|---|---|
| 0.0-1.5 | Brown silty clay (CI), soft | D | - |
| 1.5-4.5 | Grey sandy silt (ML), medium | U, SPT | 8 |
| 4.5-9.0 | Brown medium sand (SP), dense | SPT | 28 |
| 9.0-12.0 | Gravelly sand (GW), very dense | SPT | 50+ |

Boring terminated at 12.0 m. The log is used to draw soil profiles and to choose foundation type and depth.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. A borehole log is
   A. a graphical and written record of soil met in one borehole against depth
   B. a map of all boreholes at the site
   C. a bill of quantities
   D. a design drawing of the footing
   Answer: A. It records strata, samples, N values and water table for one hole. (Key point: Borehole log meaning)

2. Which belongs in the log header?
   A. Footing dimensions
   B. Borehole number, method of boring and groundwater level with date
   C. Final cost of the project
   D. Column load schedule
   Answer: B. The header gives project, borehole identity, method and GWT. (Key point: Header info)

3. Sample types in a log are marked as
   A. D for dense, U for uniform
   B. S for soft, H for hard
   C. D for disturbed, U for undisturbed and SPT
   D. Q for quick, R for rapid
   Answer: C. The column shows what sample was taken at each depth. (Key point: Sample types)