HomeMy WebLinkAboutSoils Report 09.26.2016U* -49-- 90119 Moot, f (# 1
Huddleston -Berry
Engineering & Testing. LLC
Tally Ho Construction
0145 County Road 225
Rifle, Colorado 81650
Attention: Jeff Parrington
Subject: Alternative Foundation Recommendations
Lot 4 Creek Side Estates
Rifle, Colorado
640 White Avenue
Grand Junction, Colorado 8I50i
Phone: 970-255-8005
fax: 970-255-6818
Info a huddlestonberry.com
September 26, 2016
Project#01150-0003
Reference: Geotechnical Investigation, Lois 3 and -1, Creek Side Estates, Garfield County,
Colorado by Yeh and Associates, Inc. for Empty Enterprises, LLC, May 18,
2007.
Dear Mr. Parrington,
At your request, Huddleston -Berry Engineering & Testing, LLC (HBET) prepared this letter
regarding Lot 4 of the Creek Side Estates subdivision in Rifle, Colorado. The proposed
construction at the site is anticipated to consist of a single-family residence. Based upon
information provided to HBET, the structural engineer is having difficulty meeting the
foundation design requirements outlined in the referenced report. The purpose of this letter is to
outline alternative foundation recommendations for the proposed construction.
Subsurface Conditions
The referenced report indicates that the soils at the site consist of medium stiff to stiff, slightly
sandy, silty clay and medium stiff, slightly sandy silt. Groundwater was encountered at a depth
of 14.5 feet on Lot 4 at the time of the investigation.
The native clay soils were indicated to be slightly plastic and to range from slightly collapsible to
moderately expansive. The native silt soils were indicated to be non -plastic and slightly
col lapsible.
Foundation Recommendations
The referenced report recommended spread footing foundations above undisturbed native soils.
In addition, the report recommended that foundations be designed for an allowable bearing
capacity of 3,000 psf and minimum dead -load pressure of 1,000 psf.
Lot 4 Creek Side
#OI150-0003
09/26/16
Huddleston -Berry
Based upon information provided to HBET, the structural engineer is having difficulty achieving
the minimum dead -load pressure. As an alternative to the high dead -load pressure, HBET
recommends that spread footing foundations be constructed above a minimum of 30 -inches of
structural fill.
Due to their potential for expansion, the native clay soils are not suitable for reuse as structural
fill. Imported structural fill should consist of a granular, non -expansive, non -free draining
material such as pit -run, crusher fines, or CDOT Class 6 base course. However, if pit -run is used
for structural fill, a minimum of six inches of crusher fines or Class 6 base course should be
placed on top of the pit run to prevent large point stresses on the bottoms of the footings due to
large particles in the pit -run.
Prior to placement of structural fill, it is recommended that the bottom of the foundation
excavation be scarified to a depth of 6 to 8 inches, moisture conditioned, and compacted to a
minimum of 95% of the standard Proctor maximum dry density, within ± 2% of the optimum
moisture content as determined in accordance with ASTM D698. Structural fill should extend
laterally beyond the edges of the foundation a distance equal to the thickness of structural fill.
Structural fill should be moisture conditioned, placed in maximum 8 -inch loose lifts, and
compacted to a minimum of 95% of the standard Proctor maximum dry density for fine grained
soils and 90% of the modified Proctor maximum dry density for coarse grained soils, within ±
2% of the optimum moisture content as determined in accordance with ASTM D698 and
D1557C, respectively
In general, HBET believes that the allowable bearing capacity recommended in the referenced
report is too high and may result in differential settlements. As a result
allowable bearing capacity of 2.000 psf for construction at this site. Footings subject to frost
should be at least 36 inches below the finished grade.
IBET recommends an
Non -Structural Floor Slab and Exterior Flatwork Recommendations
In order to limit the potential for excessive differential movements of slabs -on -grade it is
recommended that non-structural floor slabs be constructed above a minimum of 18 -inches of
structural fill with subgrade preparation and fill placement in accordance with the Foundation
Recommendations section of this report. It is recommended that exterior flatwork be constructed
above the native soils, below the topsoil, that have been scarified to a depth of I2 -inches,
moisture conditioned, and compacted to a minimum of 95% of the standard Proctor maximum
dry density, within 2% of the optimum moisture content as determined in accordance with
ASTM D698.
General Notes
The recommendations included above are based upon the information in the referenced report
and on our local experience. These conclusions and recommendations are valid only for the
proposed construction. Specific items not outlined in this document as part of the construction
should be in accordance with the recommendations in the referenced report.
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SOIL COMPACTION TEST REPORT
structural fill
Dale: 10/10/16
fin
Date: 10/10/16
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Moisture Counts: 152
Density Counts: 1340
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