25 May 2005
Change 1, 22 February 2006
Change 2, 4 December 2006
The minimum laboratory testing shall include grouping like samples and conducting a
sieve analysis and Atterberg Limits on one sample from the group, and performing
natural moisture content determinations to affectively depict in-situ conditions. The field
logs shall be updated in accordance with ASTM D 2487. Other testing, such as
California Bearing Ratio, unconfined compressive strength, consolidation testing, triaxial
testing, and potential volume change, such as in suspected expansive clay areas, shall
be performed as required by the contract.
Other Field Testing.
Projects may require a variety of other testing from percolation tests for septic systems
to seismic refraction surveys. In areas of near surface rock, seismic refraction surveys
or ground penetrating radar may be required to determine the depth of rock or
competent material. Soil resistivity by the Weener 4-pin method should be used when
designing underground structures such as piping.
When the contract requires a geotechnical report to be provided, provide a report
describing the physiographic and geologic features of the site. Describe the general
situation as to topography, ground cover, and any other features that may influence the
design. Describe the investigation program, exploration and testing
techniques/procedures used. Discuss the soil stratigraphy, materials, and groundwater
conditions at the site. The report shall specifically address the groundwater levels
expected to be encountered in construction under normal conditions, and any site
specific factors (such as tidal action, climate, seasonal flooding or droughts) that may
influence the groundwater levels. Include copies of pertinent U.S. Geological Survey
Maps used. The boring logs and laboratory testing results shall be provided on
compact disc (CD) in an AUTOCAD compatible format (either .DXF or .DWG) with text
size conforming to NAVFAC Standards. Include a native Adobe Acrobat (PDF) version
of the geotechnical report on the CD, and also submit two printed copies of the report.
The Geotechnical Report shall be signed by a registered Professional Engineer.
Show a scaled location plan with the borings located with offsets to existing features.
The laboratory data shall be summarized in tables.
Foundation and Site Preparation.
Discuss the facility under design and make recommendations for the foundation type.
Describe and specify the improvements that are required for shallow foundations, such
as compaction, removal and replacement, surcharging, wick drains, etc. Describe the
soil bearing capacity, anticipated settlements, seismic aspects, pile capacity, pile
length, pile type and special instructions such as jetting, pre-drilling and testing