HomeMy WebLinkAboutSoils Report 04.03.2018CIVCO Engineering, Inc.
Civil Engineering Consultants
P.O. Box 1758
365 West 50 North, Suite W-1
Vernal, Utah 84078
April 3, 2018
Shawn Ruse
Clayton Homes
671 23 Road
Grand Junction, CO 81505
Dear Shawn,
Subject. Soil Investigation - Diggs Residence at 3385 CR 311, New Castle, Colorado
I am writing to report the findings of a soil investigation that was conducted at the proposed site for the
Biggs residence that is to be built at 3385 County Road 311, New Castle, 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 sizable
proportion (36.6%) of particles that are 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 1500 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, soils with Liquid Limits less than 35% and Plasticity
Indices that less than 12%, generally are not expansive (Snethen, Johnson, and Patrick, 1977). The
soil sample tested was found to have a Liquid Limit of 27% and a Plasticity Index of 11%. Thus,
according to the referenced study, the soil in question is anticipated to be non -expansive. It should be
noted that Atterberg Limits testing does not address mineralogy and thus may have a limited ability to
reliably predict soil expansion potential.
In addition to a low degree of soil expansion, CL soils may also be susceptible to frost heave. Methods
should be implemented to lessen the likelihood of either phenomenon. Foundations should extend to
below frost depth or be frost -protected by some other means. Water should be kept away from the
foundation. 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 soil's collapse potential. In my experience, foundation failures
due to soil collapse 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 located 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.
Alluvially-deposited soils are typically not very dense and derive their strength from mineral bonds that
form between soil particles. When these soils become wet, the mineral bonds dissolve, allowing the
soil particles to consolidate (i.e. 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
Email: vanceking@civcoengineering.com
• Page 2 April 4, 2018
Verify that the project site is not al the mouth of any obvious drainage. Implementing the
aforementioned methods for lowering the risk of soil expansion and frost heave are also key to
lessening the risk of soil collapse tailure.
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 is non -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. No specific testing was performed to determine the collapse potential of the soil. 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.
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 -Biggs, New Castle CO
0_ C_ TESTING
v
native - unified soil classification Stations:
Depth:
Date Sampled
AASHTO T-27 Coarse Gradation
Sieve
Size
Weight
Ret.
"/e Ret.
% Ret.
% Total
Passing
Sieve
Size
Specs
3" (75mm)
H2O Wt.
33.2
3"
H2O %
2" (5omm)
Washed Dry Wt.
[
2"
5.9
1.5" (37.5mm)
95.1
1.5"
1" (25mm)
1"
7.5
3/4" (19mm)
93.8
3/4"
1/2" (12.5mm)
1/2"
14.2
3/8" (9 5mm)
0
0
100.0
3/8"
#4 (4 75mm)
21.3
3.8
96.2
#4
-#4 (4.75mm)
WET WT.
480 (180pm)
-#4 (4 75mm)
DRY WT.
4100 (150pm)
Total
4200 (75pm)
156.4
MF=
Tested By CN
Fine Gradation
Liquid Limit
Size
Weight
Ret.
% Ret.
% Pass
#4 (4 75mm)
Classification
clean clay CL
H2O Wt.
33.2
48 (2 36mm)
H2O %
5.9
Washed Dry Wt.
[
410 (2 Omm)
5.9
1.1
95.1
#16 (1.16mm)
420 (650pm)
7.5
1.3
93.8
#30 (600pm)
440 (425pm)
14.2
2.5
91.3
450 (300pm)
460 (250pm)
480 (180pm)
4100 (150pm)
4200 (75pm)
156.4
27.9
63.4
-#200 (75um)
7.3
1.3
Total
Remarks SOIL CLASSIFICATION (unified)
Date Tested: 3/12/2018
AASHTO T-139 8 T-90 Atterberg Limit
Liquid Limit
27
Plastic Limit
16
Plastic index
11
Classification
clean clay CL
-#4 Moisture Data
Wet Wt.
594.3
Dry Wt.
561.1
H2O Wt.
33.2
H2O %
5.9
Washed Dry Wt.
[
212.7