HomeMy WebLinkAboutSoil Investigation 07.14.17CIVCO Engineering, Inc.
Civil Engineering Consultants
P.O. Box 1758
365 West 50 North, Suite W-1
Vernal, Utah 84078
July 14, 2017
Richard Ruse
Clayton Homes
67123 Road
Grand Junction, CO 81505
Dear Richard,
Subject: Soil Investigation — Warner at TBD Odin Street, SIR, Colorado
I am writing this letter to report the findings of a soil investigation that was conducted at the proposed
site for the Warner residence at TBD Odin Street near Silt, Colorado. The investigation entailed the
analysis of one soil sample that was taken from the proposed construction site at approximately the
bearing depth of the proposed foundation. Testing of the soil sample Included a sieve analysis and
Atterberg Limits testing. The test results were used to classify the soil sample as 'CH' according to the
Unified Soil Classification System. Copies of the soil data are included with this letter.
CH sols are homogeneous inorganic days and may be silty or sandy as Is the case with this sol.
Literature suggests that medium to stiff CH soils are likely to have bearing capacities in the range of
4,000 psf. Recognizing that no specific bearing capacity testing was performed, I recommend that a
more conservative bearing capacity of 1500 psf be used for design purposes.
Over the years, a number of studies have been conducted in an effort to correlate soil shrink -swell
potential to atterberg limit data. According to one study, liquid limits less than 25% and plasticity
Indexes less than 15%, generally suggest a sol will have a low shrink/swell potential. The liquid limit of
the sample tested was found to be 39. The plasticity index for the sample was found to be 8. Thus,
according to the referenced study, the soil cannot be ruled out for being expansive. it should be noted
that Atterberg limits tests do not address mineralogy and thus may be limited in their ability to reliably
predict soil shrink -swell potential.
Every effort should be taken to limit sol moisture in the vicinity of the foundation. Walkways, driveways,
and ground surfaces should be graded to flow away from the foundation. Gutter down -spout outlets
should discharge at least five feet away from the foundation. Vegetation requiring significant watering
should not be planted near the foundation.
No testing was done to determine the collapse potential of the sol. In my experience, soil collapse
results in a far more catastrophic foundation failure than soil expansion. In every instance of soil
collapse failure that I have investigated, the damaged home was founded within a naturally occurring
alluvial fan at the outfall of a natural drainage. The figure below is not the property in question but is
Included as an example of a situation where sol collapse damage a home. Alluvial soils often derive
their strength from mineral bonds that form between loosely deposited soil particles. When these soils
become wet, the mineral bonds dissolve, allowing the soil to consolidate (i.e. collapse) under any load
Phone (435)789-5448 * Fax (435)789-44815
Email: vanceklng@civcoen_qincerin_q.com
• Page 2
July 14, 2017
In excess of that which existed the when the mineral bonds formed. To minimize the possibility of this
home being founded on collapsible soils, verify that the chosen location is nowhere near the outfall of
any natural drainage.
In summary, the soil under the foundation was not specifically tested to determine expansiveness but
results of atterberg limits testing suggest that the soil cannot be ruled out as being expansive. Likewise
the soil was not specifically tested to determine bearing capacity but was found to be of a type having
characteristic bearing capacities in the range of 4000 psf. For design purposes, a 1500 psf bearing
capacity is recommended. The home owner should make every effort to keep moisture from being
introduced to the soil near the foundation. Any future purchaser of the home should be apprised of the
underlying soil characteristics and the importance of keeping moisture away from the foundation.
This concludes my report. Please note that this investigation was performed for the purpose of
providing general information regarding the soil underlying the proposed home and makes no
prediction of foundational performance. Please contact me if you have questions regarding this report
Sincerely,
Vance V. King, PE
Engineer
CNCO Engineering, Inc.
Enclosure
Cc: Project File
Q. C. Testing. Inc
2944 S 1500 E
VERNAL, UTAH 84078
Phone (435) 789-0220
Fax (435) 781-1876
SIEVE ANALYSIS AND ATTEBERG LIMITS
Project No. or Client: CIVCO Engineering - Warner
Material Type native - unified soil classification Stations -
Distance from CL Depth: Date Sampled 6/15/2017 Date Tested-. 6115/2017
AASHTO T-27
Coarse Gradation
uyutl uW1
Sieve Weight
Size Ret.
%Total
% Rel. Passing
Sieve
Size Specs
3' (75mm)
#8 (2.3smm)
3"
2' (Som)
315.7
2"
1.5" (37.&MI
14.3
1.5"
1' (imm)
1"
314" (19mm)
#20 (awpm)
314"
1/2' (12.smm)
75-6
1/2"
3/8' (aim) 0
0 100.0
3/8"
#4 (4.75mm) 43.6
9.1 909
#4
44 (4.75mm)
WET WT.
#50 (300pm)
248
44 (4 75mm)
DRY WT.
64.9
#60 (250pm)
Total
MF=
Tested By Terry Dulxay
Size
Fine Gradation
Weight
Ret. % Ret. % Pass
uyutl uW1
#4 (4.7amm)
Row umit
131
inasw tide:
#8 (2.3smm)
Class9h;aWn
ICH fat clay)
315.7
#1 D (2.omm)
683
14.3
76.6
#16 (1.1amm)
#20 (awpm)
458
1.0
75-6
#30 (so0pm)
#40 (425pm)
263
5.5
701
#50 (300pm)
248
5.2
64.9
#60 (250pm)
#80 (190pm)
#100 (15opm)
493
103
546
#200 (?spm)
51.6
10.8
44
-#200 (75pm)
Total
3156
Remarks SOIL CLASSIFICATION (unified)
AASKM T.e9 a T-0
Atterberg Limit
uyutl uW1
39
Row umit
131
inasw tide:
8
Class9h;aWn
ICH fat clay)
44 Moisture Data
Wel Wl.
515.7
Dry WL
479.2
H2O Wt.
36.5
H2O %
7.6
Washed Dry Wt.
315.7