Specs

Proposed Bridgestone April 20, 2011
NWC of Vance St. & W. Center Ave. PSI Project No. 532281
Lakewood, Colorado Page 4 of 15
3.2.3 Laboratory Testing
The soil samples obtained during the field exploration were transported to the laboratory
and selected soil samples were tested in the laboratory to determine material properties
for our evaluation. Laboratory testing was accomplished in general accordance with
ASTM and other applicable procedures. Laboratory testing was performed on selected
samples to evaluate the classification, swell and other engineering characteristics of the
subsurface materials. Laboratory test data along with detailed descriptions of the soils
can be found on the logs of borings and in Appendix A. The samples that were not
altered by laboratory testing will be retained for 30 days from the date of this report and
then will be discarded without further notice.
4.0 GEOTECHNICAL EVALUATION
Based on the subsurface conditions observed and our experience with similar materials,
it is PSI’s opinion that the on-site soils can generally be characterized as having “high”
swell potential and the proposed development need to be designed to accommodate for
swell potential.
Due to the swell potential of the soils obtained during our site investigation, it is our
opinion that the proposed structure may be supported on a drilled pier foundation system
bearing within the sedimentary bedrock material encountered during our investigation. A
structural floor system may also be utilized for the proposed structure.
PSI provides recommendations for allowable bearing capacity and allowable skin friction
for drilled pier foundations in Section 6.0 Recommendations of this report.
Additionally, due to the swell potential of the on-site material, PSI recommends that the
subgrade to receive pavement and slab-on-grades be overexcavated and replaced as
moisture conditioned compacted fill material. PSI provides recommendations on depth
and type of moisture conditioned fill material and the amount of movement that may be
expected for each alternative. To minimize the potential for movement due to swelling
soils in the pavement areas, PSI recommends that the subgrade be chemically treated
with lime.
The following geotechnical design recommendations have been developed on the basis
of the described project characteristics and subsurface conditions encountered. Once
final design/grading plans and specifications are available, a general review by PSI is
required as a means to check that the recommendations presented in the following
sections of this report are properly interpreted and implemented.
5.0 SITE GRADING RECOMMENDATIONS
Prior to site grading or excavation for foundation construction, the site should be stripped
of vegetation, topsoil, loose uncompacted fill, soil stockpiles, and debris. The stripped
vegetation/topsoil may be re-placed as topsoil in designated landscape areas. The
loose soils or stockpiled soils may be incorporated and placed as structural fill. Trash
and debris should be disposed of in accordance with local and state regulations.
5.1 Overexcavation and Replacement – Swell Mitigation
Due to the “moderate” to “high” swell potential of the existing site soils, swell mitigation
through overexcavation and replacement should be performed to limit potential