HomeMy WebLinkAboutSoils Report 10.06.2017CIVCO Engineering, Inc.
Civil Engineering Consultants
P.O. Box 1758
365 West 50 North, Suite W-1
Vernal, Utah 84078
October 8, 2017
Brian Quintana
Clayton Homes
671 23 Road
Grand Junction, CO 81505
Dear Brian,
Subject Boil investigation - I4uck Residence In Garfield County, CO
1 am writing this letter to report the findings of a soil investigation that was conducted at the proposed
site for the Huck residence that is to be built in Garfield County, Colorado. The investigation entailed
the analysis of one soil sample that was taken at approximately the location and 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 'CL — Lean Clay' according to the
Unified Soil Classification System. A copy of the soil data is included with this letter.
CL soils are inorganic clays of low to medium plasticity. In addition to clay particles, CL soils may
contain a fair amount of gravel-, sand-, and silt -sized particles. The sample tested contained a
significant proportion (35.4%) of particles that were sand -sized (#200 Sieve) or larger. Literature
suggests that medium to stiff CL 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 2000 psf be used for design purposes.
Over the years, a number of studies have been conducted in an effort to correlate soil expansiveness
to atterberg limit data. According to one study, sods with Liquid Limits less than 60% and Plasticity
Indices that less than 35%, statistically exhibit a low potential for expansion (Snelhen, Johnson, and
Patrick, 1977). The soil sample tested was found to have a Liquid Limit of 45% and a Plasticity Index of
23%. Thus, according to the referenced study, a "low" potential exists for the soil to be expansive. It
should be noted 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 low soil expansion potential, CL soils may be
susceptible to frost heave. 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 even more catastrophic than failures due to soil expansion. In every
instance of soil collapse failure that I have investigated, the damaged home was founded at the mouth
of a pronounced drainage, such as a canyon or gully where the soil has been deposited alluvially by
intermittent runoff water flows,
Ailuvlady-deposited sods are typically not very dense and derive their strength from mineral bonds that
have formed between sod panicles. When these soils become wet, the mineral bonds dissolve,
allowing the sal particles to consolidate (Le, collapse) under any Toad that is in excess of that which
existed when the mineral bonds originally formed.
Phone (435)789-5448 * Fax (435)789-4485
• Page 2 October 6, 2097
To minimize the potential of foundation failure due to soil collapse, verify that the proposed location for
the residence is not at the mouth of any pronounced drainages.
In summary, the soil under the foundation was not specifically tested to determine its expansiveness
but results of atterberg limits testing suggest that the soil has a statistically low potential to be
expansive. Ukewise 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
2000 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
CIVCO Engineering, Inc.
Endosure
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 - Huck
Q. C. TESTING
native - unified Soil classification Stations:
Depth:
Date Sampled 10/4/2017 Date Tested:
AASHTO T-27 Coarse Gradation
Sieve
Size
Weight
•Ret.
% Ret.
% Ret.
'% Total
IPassing
Sieve
Size
Specs
3" (75mm)
100,0
17.9
3"
2.1
2" (5omm)
99.3
Washed Dry Wt.
J
2"
1.3
1.5" (37.5mm)
98.8
1.5"
4.6
1"(25mm)
97.2
1"
3/4" (19mm)
3/4"
8.0
1/2" (12.5mm)
94.4
1/2"
5.1
3/8" (9.5mm)
92.6
3/8"
9.0
#4 (4.75mm)
89.4
#4
-#4 (4.75mm)
WET WT.
#80 (180pm)
-#4 (4.75mm)
DRY WT.
#100 (15tlpm)
29.1
Total
79.1
#200 (75pm)
40.9
MF=
Tested By CN
Fine Gradation
Liquid Limit
Size
Weight
Ret.
% Ret.
% Pass
#4 (4.75mm)
0
0.0
100,0
17.9
#8 (2.36mm)
2.1
0.7
99.3
Washed Dry Wt.
J
#10 (2.0mm)
1.3
0.5
98.8
#16 (1.1emm)
4.6
1.6
97.2
420 (850pm)
#30 (6000m)
8.0
2.8
94.4
#40 (425pm)
5.1
1.8
92.6
i#50 (300pm)
9.0
3.2
89.4
460 (250pm)
#80 (180pm)
#100 (15tlpm)
29.1
10.3
79.1
#200 (75pm)
40.9
14.5
64.6
4200 (75pm)
9.3
3.3
Total
Remarks SOIL CLASSIFICATION (unified)
10/5/2017
AASHTOT.89 & T-90 Atterberg Limit
Liquid Limit
45
Plastic omit
22
Plastic Index
e
23
Classification
CL -lean clay
-44 Moisture Data
Wet Wt.
300.9
Dry Wt.
283.0
H2O Wt.
17.9
H2O %
6.3
Washed Dry Wt.
J
110.31
