HomeMy WebLinkAboutRAVEN VIEW - PDP - 12-05 - CORRESPONDENCE - GEOTECHNICAL (SOILS) REPORT"ram tarth Engineering Company, Inc.
EEC Project No. 04-01-247
August 31, 2005
Page 2
placed. The extent of the areas requiring swell mitigation should be addressed at the time
of utility installation.
Final pavement design cannot be completed until utility installation is complete. In
accordance with City of Fort Collins requirements, additional borings and laboratory
testing will be necessary to complete a final pavement design. EEC personnel can work
in conjunction with City of Fort Collins pavement management personnel to coordinate
the swell mitigation procedures and final pavement design.
We appreciate the opportunity to be of service to you on this project. If you have any
questions regarding this report or if we can be of further assistance to you in any other
way, please do not hesitate to contact us.
Very truly yours,
Earth Engineering Company, Inc.
Michael J. Coley, P.E.
Principal Engineer
Cc: Barbara Debona — Lyman, Davidson, Dooley, Inc. (7 copies)
.e- low
August 31, 2005
EARTH ENGINEERING
COMPANY, INC.
Anchor Development Corporation
1338 Catalpa Drive
Fort Collins, Colorado 80521
Attn: Mr. Russ Wells
Re: City Engineering Comments
Pavement Subgrade Preparation
Raven View Residential Development
Fort Collins, Colorado
EEC Project No. 04-01-247
Mr. Wells:
As you requested, Earth Engineering Company, Inc. (EEC) personnel completed a
geotechnical subsurface exploration report for the Raven View residential development in
Fort Collins, Colorado. That report was sent to your attention on September 30, 2004 and
included recommendations for mitigation of moderate to high swelling soils in the
pavement subgrade areas. The purpose of this letter is to address the City of Fort Collins
Engineering Department's comments regarding mitigation of the moderate to highly
swelling pavement subgrades soils.
The subsurface exploration report prepared by EEC personnel indicated a portion of the
near -surface site soils exhibited moderate to high potential for swelling with increase in
moisture content at current moisture/density conditions. In addition, claystone bedrock
was encountered near the surface in some areas. As outlined in our referenced soils
report, mitigating near surface expansive soils and bedrock beneath pavement areas
generally consists of removing the upper 3 feet of the subgrade and replacing those
materials with low -expansion potential fill which is moisture conditioned and compacted
to be within the range 94% to 98% of the material's maximum dry density as determined
in accordance with ASTM designation D-698, the standard Proctor procedure. The
moisture content of the newly placed fill soils should be adjusted to be within the range
-1% to +3% of optimum moisture content. Some pumping of the subgrade soils could
occur at the recommended moisture content and should be expected. Stabilization of the
subgrade with Class-C fly ash may be necessary after the subgrade soils have been
P.O. Box 271428 P.O. Box 49322
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