Bearings and distances for all property lines within the
The investigation must therefore be planned with
limits of work.
knowledge of the intended project size and anticipated
column loads, land utilization and a broad knowledge of
Official datum upon which elevations are based and the
the geological history of the area.
benchmark on or adjacent to the site to be used as a
The guidelines given here are not to be considered as
Official datum upon which horizontal control points
rigid. Planning of the exploration, sampling and testing
programs and close supervision must be vested in a
competent geotechnical engineer and/or engineering
If there are not already two benchmarks on the site,
geologist with experience in this type of work and
establish two permanent benchmarks.
licensed to practice engineering in the jurisdiction where
Elevations of key datum points of all building
the project is located.
structures and improvements directly adjacent and
across the street from the project site during both wet
Analysis of Existing Conditions. The report should
and dry season.
address the following:
Delineate location of any wetlands or floodplains,
Description of terrain.
underground streams or water sources.
Brief geological history.
Brief seismic history.
and Engineering Report
On most GSA projects geotechnical investigations will
take place at three separate stages: during site selection,
Description of exploration and sampling methods and
during building design, and during construction. The
outline of testing methods.
requirements for geotechnical work during site selection
Narrative of soil identification and classification, by
and during construction are described in other GSA
documents. The requirements for geotechnical work for
Narrative of difficulties and/or obstructions
the building design are defined here. They apply whether
encountered during previous explorations of existing
GSA contracts for geotechnical work separately or include
construction on or adjacent to the site.
the geotechnical investigation in the scope of the A/E
Description of laboratory test borings and results.
Plot plan, drawn to scale, showing test borings or pits.
Purpose. The purpose of the geotechnical investigation
Radon tests in areas of building location.
during building design is to determine the character and
Soils resistivity test, identifying resistivity of soil for
potential as foundations for the structure or as material
corrosion protection of underground metals and
for earthwork construction. The type of structure to be
electrical grounding design.
built and anticipated geologic and field conditions has a
significant bearing on the type of investigation to be
Surveys and Geotechnical Reports Geotechnical Investigation & Engineering Report
Revised March 2005 PBS-P100