Summary of Information to Include on a Boring Log
Summary of Information to Include on a Boring Log
Link to this table
| Include on Log | Description | Example / Photo |
|---|---|---|
| Boring name or number | Important to identify and distinguish each boring with a unique name | Most borings start with B or BH and end with a number Example: B-01 or BH01 |
| Project name, number, client, and city or county | Information is used identification purposes and for sample storage | |
| Boring coordinates and ground surface elevation | Each hole should be located and verified with coordinates in case of discrepancies If possible, record ground surface elevation with GPS Locations should be shown on a figure or map | Include Datum (NAD29 vs NAD83, NAVD 1929 or NAVD 1988) Understand coordinate systems. For example. UTM is in meters while Lat/long is in degrees or deg/min/sec |
| Start and end date and time | Helpful for tracking how long drilling is taking per borehole A known date can help identify the project for future reference |  |
| Type of drill rig and boring depth | Will be used to determine the hammer efficiency if performing blow counts
Examples include: - rubber tire ATV/buggy rig - truck rig - track rig (CME750) |
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| Drilling method | Record method used or depth where there is any change in the method being used
Different drilling methods may require different sampling techniques or procedures |
Drilling methods include: Hollow Stem Auger, Direct Push Technology, Mud Rotary, Rotosonic, Air Rotary, ODEX |
| Sampling method and sample type | Split-spoon samples (disturbed sample)
Grab samples (disturbed sample) Bulk samples such as auger cuttings Make sure to record the date, project number, borehole location, depth of sample, N value (for SPT sample), and sample number on each sample collected |
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| Sample Recovery | Record recovery of samples for comparison to length of drilled sample Note assumed reasoning for poor recovery (i.e. bedrock, gravel stuck in splitspoon) | For example, the split-spoon was pounded 18" but only 10" of soil was recovered in the sampler |
| Soil Density or Consistency | Different characterization of coarse and fine grained samples Based on N-value of sample | |
| Color | Most colors should be earth tones with descriptors
Include all mottling or redoximorphic feature colors Note iron staining or oxidized areas for indication of previously wet soil that has been dried out |
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| Grain Size | For granular samples only (not for silts and clays) Can be called: very fine-, fine-, medium-, coarse-, or very coarse-grained | |
| Particle shape | Can be angular, subangular, subrounded, or rounded Important for understanding depositional environment and weathering of soil | |
| Soil classification | USCS (most commonly used): behavioral classification: particle size, color, moisture, inclusions, granular vs. cohesive
USDA: tri-plot (shown in the caption to the right), more of a textural classification based on grain size distribution ASHTO: more of an engineering classification, based on grain size and Atterberg limits |
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| Sedimentary structure | Refers to bedding and laminations in the soil Provides insight to origin of soils or potential weathering or chemical reactions experienced Provides insight to geologic hazards (i.e. weak soil layers, collapsibility) | |
| Layer boundaries and thickness | Note stratigraphy breaks on logs Unless transition is obvious while drilling, assume it is halfway between sampling intervals | |
| Blow Counts | The number of hammer blows to pound the split-spoon 6, 12, 18, and 24 inches into the soil. The 6 to 12 and 12 to 18 inch blow counts are added and recorded as the n-value for that split-spoon. "Refusal" or termination of borehole occurs if the hammer does not advance for >50 blows/6 inches. Note the advancement (i.e. 50/2") |  |
| Depth to bedrock and/or refusal | Note refusal on logs Note sample recovery if refusal is reached in a split spoon interval | |
| Depth of groundwater | Record during and after drilling Note perched layers of water in sand or lignite Record cave depth in unstable boreholes Note if water isn't encountered Saturated silts will have high dilatancy | |
| Plasticity | Plasticity helps determine if a clay is lean (low plasticity) or fat (high plasticity) Is very dependent on moisture content (i.e. dry fat clay can seem like it has low plasticity) | |
| Moisture | Provides indication of water table. For each sample identify if it is moist, wet, or saturated | |
| Inclusions | Used to describe the secondary components in a soil sample
"With" - more than 30% of an inclusion should be included as a main descriptor "Some" - 15 to 30% "Little" - 5 to 15% |
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| Topsoil thickness | Helpful to know how much topsoil stripping may be necessary Note organic material if present or not | |
| Photographs | Pictures should be taken of each borehole locations
Take photo of stake and all four directions Record and photograph any crop damage Photograph any interesting soil samples that may be of concern |
