HomeMy WebLinkAboutSubsoil Study for Foundation Design 08.17.2021rcA äi'p;ifi',i:liÉ:fr1iiÍå
*"'
Ån ËmployeE Owned tompcny
5020 County Road 154
Glenwood Springs, CO 81601
phone: (970) 945-7988
fax: (970) 945-8454
email : kaglenwood@kumarusa.com
wwwkumarusa.com
Offrce Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
SUBSOIL STUDY
FOR FOUNDATION DESIGN
PROPOSED CONTAINER
TRACT 27, ANTLERS ORCHARD
TBD COTJNTY ROAD 237
GARFIELD COUNTY, COLORADO
PROJECT NO.2t-7-447
AUGUST 17,2021
PREPARED FOR:
JOSE ROBERTO MUNOZ
50591 HIGHWAY 6, SPACE 17
GLENWOOD SPRINGS' COLORADO 81601
i osemun ozgastelu m64@gmail.com
TABLE OF CONTENTS
PURPOSE AND SCOPE OF STUDY
PROPOSED CONSTRUCTION
SITE CONDITIONS
FIELD EXPLORATION
SUBSURFACE CONDITIONS
DESIGN RECOMMENDATIONS
FOUNDATIONS
FLOOR SLABS
UNDERDRAIN SYSTEM
SURFACE DRAINAGE.......
LIMITATIONS.......
FIGURE 1 - LOCATION OF EXPLORATORY BORINGS
FIGURE 2 - LOGS OF EXPLORATORY BORINGS
FIGURE 3 - LEGEND AND NOTES
I
1
I
f
.,
-L-
4
Kumar & Associates, lnc. @ Project No. 21-7'447
PURPOSE AND SCOPE OF STUDY
This report presents the results of a subsoil study for a proposed container building to be located
on Tract 27, Antlers Orchard, TBD County Road237, 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 proposal for geotechnical
engineering services to Jose Roberto Munoz dated May 11,2021.
A field exploration program consisting of exploratory borings was conducted to obtain
information on the subsurface conditions. Samples of the subsoils and bedrock were obtained
during the field exploration and classified. The results of the field exploration were analyzedto
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 container building will be a single-story structure with a foot print of
approximately 40 by 80 feet. Ground floor will be slab-on-grade. Grading for the structure is
assumed to be relatively minor with cut depths between about I to 4 feet. We assume relatively
light foundation loadings, 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 subject site was undeveloped with a storage container present at the time of our field
exploration. The ground surface is sloping down to the north at a grade of around 15 percent.
Elevation difference across the proposed building fooþrint is approximately 5 feet. Vegetation
consists of weeds, sagebrush and cedar trees. Gravel and cobbles are present on the surface and
sandstone bedrock is outcropping uphill of the building area.
FIELD EXPLORATION
The field exploration for the project was conducted on June 4, 2021. Two exploratory borings
were drilled at the locations shown on Figure 1 to evaluate the subsurface conditions. The
Kumar & Associates, lnc. @ Project No. 21-7-447
",
borings were advanced with 4-inch diameter continuous flight augers powered by a truck-
mounted CME-458 drill rig. The borings were logged by a representative of Kumar &
Associates,Inc.
Samples of the subsoils were taken with l% inch and 2 inch I.D. 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-I586,
The penetration resistance values ate an indication of the relative density or consistency of the
subsoils and hardness of the bedrock. 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.
SUBSURF'ACE CONDITIONS
Graphic logs of the subsurface conditions encountered at the site are shown on Figure 2. The
subsoils consist of about 1 foot of silty sand root zone overlying sandstone bedrock down to the
maximum explored depth of 2I feet.
No free water was encountered in the borings at the time of drilling and the bedrock was slightly
moist.
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 or a slab
bearing on the natural sandstone bedrock.
The design and construction criteria presented below should be observed for a spread footing
foundation system.
1) Footings placed on the undisturbed sandstone bedrock or up to 2 feet ofstructural
fill should be designed for an allowable of
expenence, we expect settlement of footings designed and constructed
discussed in this section will be about I inch or less.
2) The footings should have a minimum width of 16 inches for continuous walls and
2 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
Based on
AS
Kumar & Associates, lnc. @ Project No. 21-7-447
a--t-
4)
of foundations at least-l.,6j.nc-hesrþelow exterior grade is typically used in this
area. Shallower footings should be protected from frost heave with insulation.
Continuous foundation walls should be reinforced top and bottom to span local
anomalies such as by assuming an unsupported length of at least 10 feet.
Foundation walls acting as retaining structures (if any) should also be designed to
resist a lateral earth pressure corresponding to an equivalent fluid unit weight of at
least 45 pcf.
Topsoil and any loose disturbed soils should be removed and the footing bearing
level extended down to the undisturbed sandstone bedrock up to 2 feet of
structural fill can be placed below foundation grade ifneeded. The structural fill
should consist of 3/¿-inchroad base compacted to at least 98Yo of the maximum
standard Proctor density at a moisture content near optimum. The exposed
material in footing area should then be moistened and compacted.
A representative ofthe geotechnical engineer should observe all footing
excavations prior to concrete placement to evaluate bearing conditions.
s)
FLOOR SLABS
The natural on-site sandstone bedrock, exclusive of topsoil, is suitable to support lightly to
moderately loaded slab-on-grade construction. 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 free-draining gravel should be placed beneath slabs-on-grade to
facilitate drainage. This material should consist of minus 2-inchaggregate with at least 50%
retained on the No. 4 sieve and less than 2o/o passing the No. 200 sieve.
All fill materials for support of floor slabs should be compacted to at least 95Yo of maximum
standard Proctor density at a moisture content near optimum. Required fill can consist of
imported 3/+-inch road base.
UNDERDRAIN SYSTEM
It is our understanding the proposed ground floor elevation is near the surrounding grade and
slab-on-grade. Therefore, a foundation drain system is not recommended. It has been our
experience in the area and where bedrock is shallow that local perched gtoundwater can develop
6)
Kumar & Associates, lnc. @ Project No. 21-7-447
4
during times of heavy precipitation or seasonal runoff. Frozen ground during spring runoff can
also create a perched condition. If below grade construction is considered, we recommend an
underdrain be provided to protect this construction from wetting and hydrostatic pressure
buildup.
If the finished floor elevation of the proposed container building is revised to have a floor level
below the surrounding grade or a tall crawlspace construction, we should be contacted to provide
recommendations for an underdrain system. All earth retaining structures (site walls) should be
properly drained.
SURFACE DRAINAGE
The following drainage precautions should be observed during construction and maintained at all
times after the container building has been completed:
1) Inundation ofthe 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 95Yo of the maximum standard Proctor density in pavement and slab areas
and to at least 90o/o 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 12 inches in the first 10 feet in unpaved areas and a minimum slope of
3 inches in the first 10 feet in paved areas. Free-draining wall backfill (if any)
should be covered with filter fabric and capped with about 2 feet of the on-site
soils to reduce surface water infiltration.
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 areaat 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
Kumar & Associates, lnc. @ Project No. 21-7-447
-5-
presence, prevention or possibility of mold or other biological contaminants (MOBC) developing
in the future. If the client is concemed 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.
This report has been prepared for the exclusive use by our client for design purposes. We are not
responsible for technica! 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 veriff 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.
Respectfu lly Submitted,
Ku$åar & Àssocåatssu ãmc"
James H. Parsons, P
Reviewed by:
Daniel E. Hardin, P.E.
JHP/kac
tl'
rl,*.
8/2.I
58663
Kumar & Âasc *i.at*s, ln*. €t Prcjeet I'lo" 21"7-â47
g
a--'. Lc
,-., a'
't
' .2
ç,è"i. JiT;
a..'
TE PROPOSED
E'l
a
{
t
,?
åa.
tl
,.
'¡'
ì?
i
50
APPROXIMATE SCALE_FEET
Fig. 1Kumar & Associates LOCATION OF EXPLORATORY BORINGS21 -7 -447
BORING 1 BORING 2
0 0
50/2 s7 /12
5
50/1 50/ 4
5
so/1.5 50/2.s
l0 50/1.5 10
FLJ
l¡Jl!
I-FfL
l¡Jô
50/0.75 È-
t¡J
l¡J
LL
I
:EFo-
LJo
t5 50/3 15so/ 1
20 20
50/o.75 50/O.25
25 25
21-7 -447 Kumar & Associates LOGS OF EXPLORATORY BORINGS Fig. 2
Ê
I
É
I
LEGEND
SAND (SM); SILTY, SLIGHTLY CLAYEY TO CLAYEY, SLIGHTLY MolST, TAN
SANDSTONE BEDROCK; FINE GRAINED, SCATTERED SILTSTONE LAYERS, MEDIUM HARD TO
HARD, SLIGHTLY MOIST, GREY AND TAN
DRIVE SAMPLE, 2-INCH I.D" CALIFORNIA LINER SAMPLE.
i DRTVE SAMPLE, 1 3/B-|NCH l.D. SPLIT SPOON STANDARD PENETRATTON TEST
En zn DRIVE SAMPLE BLOW COUNT. INDICATES THAT 50 BLOWS OF A 1 40-POUND HAMMER--l . FALLING 30 INCHES WERE REQUIRED To DRIVE THE SAMPLER 2 INCHES.
NOTES
1 THE EXPLORATORY BORINGS WERE DRILLED ON JUNE 4, 2021 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
21 -7 -447 Kumar & Associates LEGEND AND NOTES Fig.3