HomeMy WebLinkAboutSoils Report 08.17.2017CIVCO Engineering, Inc.
Civil Engineering Consultants
P.O. Box 1758
365 West 50 North, Suite W-1
Vernal, Utah 84078
August 17, 2017
Shawn Ruse
Clayton Hames
671 23 Road
Grand Junction, CO 81505
Dear Shawn,
Subject Soil Investigation - Baker Residence, Parchute, Colorado
I am writing this letter to report the findings of a soil investigation that was conducted at the proposed
site for the Baker residence that is to be bulit in or near Parachute, 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 results of the soil testing were used to classify the soil sample as 'SW'
according to the Unified Soil Classification System. A copy of the soil data is included with this letter.
SW soils are well -graded sands. Bearing capacities for for SW soils are typically 6000 psi for loose
soils. Recognizing that no specific testing was conducted to determine the soils actual bearing
capacity, I recommend that a smaller bearing capacity of 2000 psf be used for design of the home's
foundation.
No specific testing was done to determine the expansion potential of the soil sample. Atterberg limits
test results suggest a relatively low potential for expansion. Over the years, a number of studies have
been conducted in an effort to correlate soil shrink -swell potential 10 atterberg limit data. According to
one study, soils having liquid limits Tess than 50% and plasticity indexes less than 25%, generally have
lower shrink/swell potentials. The tested soil sample had a measured liquid limit of 40% and a plasticity
index of 15%. Please note that Atterberg limits testing does not address mineralogy and thus may be
limited in its ability to reliably predict soil shrink -swell potential.
Though the Atterberg Limits testing suggests a non -expansive soil, frost heave could still cause
problems for the foundation. Foundations should extend to below frost depth or be frost -protected by
some other means. Water should be kept away from the foundations. Walkways, driveways, and
ground surfaces should be graded to flow away from the foundation. Gutter down -spout outlets should
be kept 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 soil. In my experience, soil collapse
foundation failures are generally more catastrophic than failures due to 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. An example of such a situation is
shown in the figure below.
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
(Le. collapse) under any load in excess of that which existed the when the mineral bonds originally
formed. To minimize the possibility of the home being founded on collapsible soils, verify that the
chosen location is nowhere near the outfall of any natural drainage.
Phone (435)789-5448 * Fax (435)789-4485
Email: vancekinaecivcoenaineerina.com
• Page 2
August 17, 2017
In summary, the soil under the foundation was not specifically tested to determine expansiveness but
results of atterberg limits testing suggest that the soil has a relatively low potential for expansion.
Likewise the soil was not specifically tested to determine bearing capacity but was found to be of a type
having presumptive bearing capacities in the range of 6000 psf. For design purposes, a 2000 psf
bearing capacity is recommended. The home owner should make every effort to keep moisture from
being introduced to the sail 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
CIVCO 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
Project No or Client:
Material Type
Distance from CL:
SIEVE ANALYSIS AND ATTEBERG LIMITS
CIVCO Engineering - Baker residence. W Parachute. CO
native - unified so I classlficaUon Stations
Depth:
Date Sampled 7/19/2017 Date Tested.
AASHTO T-27 Coarse Gradation
Sieve
Size
Weight
Ret.
% Ret.
% Rel.
% Total
Passing
Sieve
Size
Specs
3" Pte)
H2O Wt.
9.4
3"
H2O % 42.1
2" maim)
0
0
Washed Dry Wt.
-
100
2'
68.9
1.5" m37.smm1
195.3
3.0
97.0
1.5"
1"t2snn)
198.2
3.1
93.9
1"
314' mew)
55.1
0.6
93.1
314"
112" f12Smn)
243.1
3.7
89.4
112"
92.7
318" ia.smm)
202.7
3.1
86.3
318"
#414 751rm}
606 9
9.4
76.9
#4
-#414 73mm)
WET WT.
5093.3
#80(tSemi
_
#414 7smm)
DRY WT.
4986.3
76.9
#tOQ (tsovm)
61.8
Total
6487 6
38.6
#200 psvm)
54 6
MF=
Tested By Terry Dubray
Fine Gradation
Liquid Wilt
Size
Weight
Ret.
% Rel.
% Pass
#4 (4.75mm1
Cussdwuon
SM -well graded, sand with clay
H2O Wt.
9.4
#8 (2.36mm)
H2O % 42.1
Washed Dry Wt.
1
#10 (2.0mm)
68.9
15 4
11.6
65 1
#16 (t team
#20 imam)
#30 mow)
#40 (4250m)
92.7
20 7
15.9
49 2
#50 (300vm)
#6012sovmi
#80(tSemi
_
#tOQ (tsovm)
61.8
13.8
10.6
38.6
#200 psvm)
54 6
12.2
9.4
29.2
4200 (75pm)
13.3
3
_
Total
4482
Remarks SOIL CLASSIFICATION (unified)
7/20/2017
AASHTO T.e9 6 T40 Alterberg Limit
Liquid Wilt
40
Piritic unlit
25
Plastic Inds.
15
Cussdwuon
SM -well graded, sand with clay
& gravel
44 Moisture Data
Wet Wt.
457.6
Dry WL
448.2
H2O Wt.
9.4
H2O % 42.1
Washed Dry Wt.
1
292 4