HomeMy WebLinkAboutSoils Report 11.09.2018AR
Geotechnical Engineering 1 Engineering Geology
Materials Testing 1 Environmental
5020 County Road 154
Glenwood Springs, CO 81601
Phone: (970) 945-7988
Fax: (970) 945-8454
Email: hpkglenwood@kumarusa.com
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, Summit County, Colorado
SUBSOIL STUDY
FOR FOUNDATION DESIGN
PROPOSED VEHICLE BARN
45755 US HIGHWAY 6
GARFIELD COUNTY, COLORADO
PROJECT NO. 18-7-639
NOVEMBER 9, 2018
PREPARED FOR:
VICCOS, LLC
ATTN: BART VICTOR
0607 WESTBANK ROAD
GLENWOOD SPRINGS, COLORADO 81601
Viccol@comcast.com
RECEIVED
JAN 1 4 2019
GARFIELD COUNTY
COMMUNITY DEVELOPMENT
TABLE OF CONTENTS
PURPOSE AND SCOPE OF STUDY - 1 -
PROPOSED CONSTRUCTION - 1 -
SITE CONDITIONS - 1 -
FIELD EXPLORATION - 2 -
SUBSURFACE CONDITIONS - 2 -
FOUNDATION BEARING CONDITIONS - 3 -
DESIGN RECOMMENDATIONS - 3 -
FOUNDATIONS - 3 -
FLOOR SLABS _ 4
SURFACE DRAINAGE - 5 -
LIMITATIONS - 5 -
FIGURE 1 - LOCATION OF EXPLORATORY BORINGS
FIGURE 2 - LOGS OF EXPLORATORY BORINGS
FIGURE 3 - LEGEND AND NOTES
FIGURE 4 - SWELL -CONSOLIDATION TEST RESULTS
TABLE 1- SUMMARY OF LABORATORY TEST RESULTS
H-P%KUMAR
Project No. 18-7-639
PURPOSE AND SCOPE OF STUDY
This report presents the results of a subsoil study for a proposed vehicle barn to be located at
45755 US Highway 6, Garfield County, Colorado. The project site is shown on Figure 1. The
purpose of the study was to develop recommendations for the foundation design. The study was
conducted in accordance with our agreement for professional geotechnical engineering services
to Viccos, LLC dated October 17, 2018.
A field exploration program consisting of exploratory borings was conducted to obtain
information on the subsurface conditions. Samples of the subsoils obtained during the field
exploration were tested in the laboratory to determine their classification, compressibility or
swell and other engineering characteristics. The results of the field exploration and laboratory
testing were analyzed to develop recommendations for foundation types, depths and allowable
pressures for the proposed building foundation. This report summarizes the data obtained during
this study and presents our conclusions, design recommendations and other geotechnical
engineering considerations based on the proposed construction and the subsurface conditions
encountered.
PROPOSED CONSTRUCTION
The proposed building will be a pre-engineered steel structure about 6,000 square feet in plan
size located between the exploratory borings shown on Figure 1. Ground floor will be slab -on -
grade. Grading for the structure is assumed to be relatively minor with cut/fill depths between
about 2 to 4 feet. We assume relatively light to moderate foundation loadings including
concentrated column loads, typical of the proposed type of construction.
If building loadings, location or grading plans change significantly from those described above,
we should be notified to re-evaluate the recommendations contained in this report.
SITE CONDITIONS
The property is occupied by the existing structures shown on Figure 1. The current proposed
building site is vacant and vegetated with grass and weeds and scattered trees nearby. The
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Project No. 18-7-639
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ground surface is gently sloping down to the south with around 2 feet of elevation difference
across the building site.
FIELD EXPLORATION
The field exploration for the project was conducted on October 30, 2018. Two exploratory
borings were drilled at the locations shown on Figure 1 to evaluate the subsurface conditions.
The borings were advanced with 4 -inch diameter continuous flight augers powered by truck-
mounted CME -45B drill rig. The borings were logged by a representative of H-P/Kumar.
Samples of the subsoils were taken with 1% inch and 2 inch LD. spoon samplers. The samplers
were driven into the subsoils at various depths with blows from a 140 pound hammer falling 30
inches. This test is similar to the standard penetration test described by ASTM Method D-1586.
The penetration resistance values are an indication of the relative density or consistency of the
subsoils. Depths at which the samples were taken and the penetration resistance values are
shown on the Logs of Exploratory Borings, Figure 2. The samples were returned to our
laboratory for review by the project engineer and testing.
SUBSURFACE CONDITIONS
Graphic logs of the subsurface conditions encountered at the site are shown on Figure 2. The
subsoils consist of about 'h foot of topsoil overlying medium stiff to soft, sandy silt to a depth of
about 8 feet where dense, silty sandy gravel and cobbles was encountered. Drilling in the dense
granular soils with auger equipment was difficult due to the cobbles and boulders and drilling
refusal was encountered in the deposit.
Laboratory testing performed on samples obtained from the borings included natural moisture
content and density, finer than sand size gradation analyses, liquid and plastic limits and
unconfined compressive strength. Results of swell -consolidation testing performed on a
relatively undisturbed drive sample of the silt, presented on Figure 4, indicate moderate
compressibility under conditions of loading and wetting. Results of unconfined compressive
strength indicate the silt to have medium stiff consistency. The laboratory testing is summarized
in Table 1.
H-P%KUMAR
Project No. 18-7-639
ve low bearing capacity with moderate compressibility
3..
No free water was encountered in the borings at the time of drilling and the subsoils were moist
to very moist with depth.
FOUNDATION BEARING CONDITIONS
The upper silt soils at shallow depth ha
potential. Shallow spread footings placed on the silt soils and sized for low bearing pressure
with settlement potential can be used for foundation support.
The settlement potential can be
reduced by use of structural fill below the footings or extending the bearing level down to the
dense granular soils.
DESIGN RECOMMENDATIONS
FOUNDATIONS
Considering the subsurface conditions encountered in the exploratory borings and the nature of
the proposed construction, we recommend the building be founded with spread footings bearing
on the natural soils with moderate settlement potential or on compacted granular structural fill
with less settlement potential. Alternately, a deep foundation such as helical piers could be used
for a low settlement potential and moderate load capacity.
The design and construction criteria presented below should be observed for a
foundation system.
1) Footings placed on the undisturbed natural soils should be designed for an
allowable bearing pressure of 1,000 psf. Based on experience, we expect
settlement of footings designed and constructed as discussed in this section will
spread footing
be up to about 1 inch.
Spread footings placed on at least 2 feet of compacted
structural fill can be designed for an allowable bearing pressure of 2,000 psf with
a settlement potential up to about 1 inch.
2) The footings should have a minimum width of 18 inches for continuous walls and
3 feet for isolated pads.
3) Exterior footings and footings beneath unheated areas should be provided with
adequate soil cover above their bearing elevation for frost protection. Placement
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Project No. 18-7-639
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of foundations at least 30 inches below exterior grade is typically used in this
area.
4) Continuous foundation walls should be heavily reinforced top and bottom to span
local anomalies such as by assuming an unsupported length of at least 14 feet.
5) The topsoil and loose disturbed soils should be removed and the footing bearing
level extended down to the firm natural soils. Structural fill should consist of
well -graded granular soil such as road base extending at least one foot beyond the
footing edges compacted to at least 98% of standard Proctor density at near
optimum moisture content. The natural silt soils are highly moist and use of a
subgrade stabilization mat may be required to help achieve compaction on the
initial lift of structural fill.
6) A representative of the geotechnical engineer should evaluate compaction of
structural fill and observe all footing excavations prior to concrete placement to
evaluate bearing conditions.
FLOOR SLABS
The natural on-site soils, exclusive of topsoil, can be used to support lightly loaded slab -on -grade
construction with settlement potential similar to spread footings. To reduce the effects of some
differential movement, floor slabs should be separated from all bearing walls and columns with
expansion joints which allow unrestrained vertical movement. Floor slab control joints should
be used to reduce damage due to shrinkage cracking. The requirements for joint spacing and
slab reinforcement should be established by the designer based on experience and the intended
slab use. A minimum 4 -inch layer of relatively well graded sand and gravel such as Class 6 road
base should be placed beneath slabs to facilitate drainage. This material should consist of minus
2 -inch aggregate with at least 50% retained on the No. 4 sieve and less than 12% passing the No.
200 sieve.
All fill materials for support of floor slabs should be compacted to at least 95% of maximum
standard Proctor density at a moisture content near optimum. Required fill should consist of
imported granular soils devoid of vegetation, topsoil and oversized rock.
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Project No. 18-7-639
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SURFACE DRAINAGE
The following drainage precautions should be observed during construction and maintained at all
times after the building has been completed:
1) Inundation of the foundation excavations and underslab areas should be avoided
during construction.
2) Exterior backfill should be adjusted to near optimum moisture and compacted to
at least 95% of the maximum standard Proctor density in pavement and slab areas
and to at least 90% of the maximum standard Proctor density in landscape areas.
3) The ground surface surrounding the exterior of the building should be sloped to
drain away from the foundation in all directions. We recommend a minimum
slope of 6 inches in the first 10 feet in unpaved areas and a minimum slope of 3
inches in the first 10 feet in paved areas.
4) Roof downspouts and drains should discharge well beyond the limits of all
backfill.
5) Landscaping which requires regular heavy irrigation should be located at least 5
feet from foundation walls.
LIMITATIONS
This study has been conducted in accordance with generally accepted geotechnical engineering
principles and practices in this area at this time. We make no warranty either express or implied.
The conclusions and recommendations submitted in this report are based upon the data obtained
from the exploratory borings drilled at the locations indicated on Figure 1, the proposed type of
construction and our experience in the area. Our services do not include determining the
presence, prevention or possibility of mold or other biological contaminants (MOBC) developing
in the future. If the client is concerned about MOBC, then a professional in this special field of
practice should be consulted. Our findings include interpolation and extrapolation of the
subsurface conditions identified at the exploratory borings and variations in the subsurface
conditions may not become evident until excavation is performed. If conditions encountered
during construction appear different from those described in this report, we should be notified so
that re-evaluation of the recommendations may be made.
H-P%KUMAR
Project No. 18-7-639
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This report has been prepared for the exclusive use by our client for design purposes. We are not
responsible for technical interpretations by others of our information. As the project evolves, we
should provide continued consultation and field services during construction to review and
monitor the implementation of our recommendations, and to verify that the recommendations
have been appropriately interpreted. Significant design changes may require additional analysis
or modifications to the recommendations presented herein. We recommend on-site observation
of excavations and foundation bearing strata and testing of structural fill by a representative of
the geotechnical engineer.
Respectfully Submitted,
H -Pt KUMAR
Steven L. Pawlak, P.E.
Reviewed by:
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Daniel E. Hardin, P.E.
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H -P- KUMAR
Project No. 18-7-639
LOT 69, BLOCK 18
CANYON CREEK
ESTATES
2nd AMENDED
:'� EXISTING
GARAGE
•
■
■•
•
•
1.61/161,
25 0 25 50
SCALE -FEET
18-7-639
RE
EXISTING
HOUSE
1
-0- -
•
•
-'dam
EXISTING
SHOP
•
BORING 2
•
••
••
•
PREVIOUS PROPOSED
LEACH FIELD
BORING 1
1
•
•
1
1
L
US HIGHWAY 6 & 24
•
•
•
H-PtiKIJIMAR
LOCATION OF EXPLORATORY BORINGS
Fig. 1
1-
w
w
w
I
2
F-
a
w
0
0
- 5
- 10
BORING 1
7/12
WC=18.7
DD=103
6/12
BORING 2
5/12
WC=17.0
DD=106
-200=60
LL=20
P1=2
UC=900
3/12
50/8
0 ----
5
10
15 15
18-7-639
H-PtiKUMAP
LOGS OF EXPLORATORY BORINGS
Fig. 2
LEGEND
1 TOPSOIL; ORGANIC SANDY SILT, VERY MOIST, BROWN.
` SILT (ML); SANDY TO VERY SANDY, SLIGHTLY CLAYEY, MOIST AND STIFF TO VERY MOIST
AND SOFT WITH DEPTH, BROWN.
GRAVEL AND COBBLES (GM); SILTY, SANDY, PROBABLE BOULDERS, DENSE, MOIST,
GRAY—BROWN. ROUNDED ROCK.
J
7/12
NOTES
RELATIVELY UNDISTURBED DRIVE SAMPLE; 2—INCH I.D. CALIFORNIA LINER SAMPLE.
DRIVE SAMPLE; STANDARD PENETRATION TEST (SPT), 1 3/8 INCH I.D. SPLIT SPOON
SAMPLE, ASTM D-1586.
DRIVE SAMPLE BLOW COUNT. INDICATES THAT 7 BLOWS OF A 140—POUND HAMMER
FALLING 30 INCHES WERE REQUIRED TO DRIVE THE CALIFORNIA OR SPT SAMPLER 12 INCHES.
PRACTICAL AUGER REFUSAL.
DEPTH AT WHICH BORING CAVED FOLLOWING DRILLING.
1. THE EXPLORATORY BORINGS WERE DRILLED ON OCTOBER 30, 2018 WITH A 4—INCH DIAMETER
CONTINUOUS FLIGHT POWER AUGER.
2. THE LOCATIONS OF THE EXPLORATORY BORINGS WERE MEASURED APPROXIMATELY BY PACING
FROM FEATURES SHOWN ON THE SITE PLAN PROVIDED.
3. THE ELEVATIONS OF THE EXPLORATORY BORINGS WERE NOT MEASURED AND THE LOGS OF THE
EXPLORATORY BORINGS ARE PLOTTED TO DEPTH.
4. THE EXPLORATORY BORING LOCATIONS SHOULD BE CONSIDERED ACCURATE ONLY TO THE
DEGREE IMPLIED BY THE METHOD USED.
5. THE LINES BETWEEN MATERIALS SHOWN ON THE EXPLORATORY BORING LOGS REPRESENT THE
APPROXIMATE BOUNDARIES BETWEEN MATERIAL TYPES AND THE TRANSITIONS MAY BE GRADUAL.
6. GROUNDWATER WAS NOT ENCOUNTERED IN THE BORINGS AT THE TIME OF DRILLING.
7. LABORATORY TEST RESULTS:
WC = WATER CONTENT (%) (ASTM D 2216);
DD = DRY DENSITY (pcf) (ASTM D 2216);
—200= PERCENTAGE PASSING NO. 200 SIEVE (ASTM D 1140);
LL = LIQUID LIMIT (ASTM D 4318);
PI = PLASTICITY INDEX (ASTM D 4318);
UC = UNCONFINED COMPRESSIVE STRENGTH (psf) (ASTM D 2166).
18-7-639
H -P KUMAR
LEGEND AND NOTES
Fig. 3
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CONSOLIDATION - SWELL (%)
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H-P�KUMAR
TABLE 1
SUMMARY OF LABORATORY TEST RESULTS
Project No. 18-7-639
SAMPLE LOCATION NATURAL NATURAL
BORING DEPTH CONTENT DENSITY
(ft) (%) (pcf)
MOISTURE DRY
GRADATION ATTERBERG LIMITS I
PERCENT UNCONFINED
GRAVEL SAND I PASSING LIQUID PLASTIC COMPRESSIVE 1
(%) (%) NO. 200 LIMIT INDEX STRENGTH
SIEVE
(psf)
SOIL TYPE
1
2%
18.7
103
Sandy Silt
2
2'/2
17.0
106
60
20
2
900
Sandy Silt