Lesson 3/Learning Event 2
Exploration borings generally should be conducted at the point of interest, and located in a manner to get
the maximum value from each boring. This may require exploration borings in the centerline as well as
edges of runways or roads, but no specific pattern should be employed except perhaps a staggered or
offset pattern, to permit the greatest coverage.
It is generally accepted policy to conduct the exploration borings at the edges of existing pavements,
unless these pavements have failed completely, in which case the reason for the failure should be found.
Large cuts and fills are the most important areas for detailed exploration.
Depth of Exploration in the Theater of Operations. The cut section should be four feet below
subgrade, if possible. (The fill section should be four feet below original ground level, if possible.)
Effort should be made to locate the ground water table.
Procedures in Sampling
Exploration holes or pits must be carefully logged. Samples must be accurately located and numbered.
The elevation and exact location of each hole should be determined and tied into the site layout.
Preparation of Soil Profile
The soils profile shows boundaries of soil strata, location and depth of test holes and samples, elevation
of bedrock, and water table. Laboratory test results should be included when available. The soils profile
is used to locate grade line, for excavation and grading plan, and for drainage plan.