Lesson 3/Learning Event 2
RECOMMENDED PROCEDURES FOR SOIL SURVEYS
The following guide and step-by-step procedures are a summary and review of soils exploration.
Objective of Soil Exploration
Soil Types and Securing of Samples.
Condition of Soil In-place.
Density
Moisture content.
Drainage Characteristics.
Depth to Ground Water and Bedrock
Development of a Soil Profile for the Area.
Sources of Information
Published Information.
Geological and topographical reports, and maps.
Agricultural soil bulletins and maps-require careful interpretation and knowledge of local
terms.
Aerial photographs-used to predict subsurface conditions.
Previous explorations for nearby construction projects.
Field Information
General observation of road cuts, stream banks, eroded slopes, earth cellars, mine shafts, existing pits
and quarries, etc.
Test holes made with hand auger or power auger if necessary and available.
Test pits, necessary where hand auger cannot penetrate, or large samples are required.
Local inhabitants-preferably trained observers such as contractors, engineers, quarrymen, etc.
Planning of General Layout
Primary Objective. The primary objective is to determine the extent of the various soil types,
vertically and laterally, within the zone where earthwork may occur.
Airfields Exploration. Place borings at high and low spots, wherever a soil change is expected, and
in transitions from cut to fill. There is no maximum or minimum spacing requirement between holes;
however, the number of holes must be sufficient to give a complete and continuous picture of the soil
layers throughout the area of interest. As a general rule, the number of exploration borings required on a
flat terrain with uniform soil condition will be less than in a terrain where the soil conditions change
rather frequently.
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