HomeMy WebLinkAboutSubsoils Report for Foundation Designl(tn Kunar & Associates, lnc.@
Geotechnical and Materials Engineers
and Environmental Scientists
An Employaa Owned ComPonY
5020 CountY Road 154
Glenwood Springs, CO 81601
phone: (970) 945-7988
fax: (970) 945-8454
email: kaglenwood@kumarusa.com
www.kumarusa.colo
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins,Glenwood Springs, and Summit County, Colorado
SUBSOIL STUDY
FOR FOUNDATION DESIGN
PROPOSED SHOP BUILDING
PARCEL NO. 212733200374, COUNTY ROAD 233
RIFLE, COLORADO
PROJECT NO.24-7-583
ocToBER 21,2024
PRT,PARED FOR:
JILL & MIKE CIIRISTIANSON
2601 COUNTY ROAD 233
RTFLE, COLORADO 81650
i amch ristianson@msn.com
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PURPOSE AND SCOPE OF STUDY
This report presents the results ofa subsoil study for a proposed shop to be located on parcel
212733200374 alongcounty Road 233, adjacent to 2601county Road 233, Rifle, 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 geotechnical engineering services to Jill and Mike Christianson dated October 7,
2024.
A field exploration program consisting of one exploratory boring was conducted to obtain
information on the subsurface conditions. Samples of the subsoils and bedrock 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 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 shop will be a single-story structure with a slab-on-grade ground floor' Grading
for the structure is assumed to be relatively minor with cut depths between about 2 to 3 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 lot was mostly undeveloped at the time of our field exploration' The site appears to
have undergone some minor cut grading for equipment and trailer storage purposes' The ground
surface in the proposed shop area slopes moderately down to the southwest at grades between 5
to l}Yo. The vegetation consists of grass, weeds, sage brush, and juniper trees'
FIELD EXPLORATION
ect was conducted on October 9,2024. One exploratoryloration for the
boring was advanced with 4-inch
CME-458 drill rig. The borings
diameter continuous flight augers powered by a truck-mounted
were logged by a representative of Kumar & Associates, Inc'
Kumar & Associates, lnc' @ Project No, 2b7-583
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The design and construction criteria presented below should be observed for a spread footing
foundation system.
1) Footings placed on the undisturbed natural granular soils should be designed for
an allowable bearing pressure of 1,200 psf. Based on experience, we expect
settlement of footings designed and constructed as discussed in this section will
be about 1 inch or less. There could be some additional post-construction
settlement on the order of I to 2 inches, primarily if the bearing soils were to
become wetted'
2) The footings should have a minimum width of 18 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
of foundations at least 36 inches below exterior grade is typically used in this
atea.
4) Continuous foundation walls should be reinforced top and bottom to span local
anomalies such as by assuming an unsupported length of at least 12 feet.
Foundation walls acting as retaining structures should also be designed to resist a
lateral earth pressure coffesponding to an equivalent fluid unit weight of at least
55 pcf.
5) All existing fill, topsoil and any loose or disturbed soils should be removed and
the footing bearing level extended down to firm natural soils. The exposed soils
in footing area should then be moistened and compacted. If water seepage is
encountered, the footing areas should be dewatered before concrete placement.
6) A representative ofthe geotechnical engineer should observe all footing
excavations prior to concrete placement to evaluate bearing conditions.
FLOOR SLABS
The natural on-site soils, exclusive of topsoil, are suitable to support lightly loaded slab-on-grade
construction. The soils are typically compressible when wetted. 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 should be placed
least 50% retained on the No. 4 sieve
All fill materials for support of floor slabs should be compacted to at least95o/o of maximum
standard Proctor density at a moisture content near optimum.
and less than 12o/o Passing the No. 200 sieve
Kumar & Associates, lnc. @ Project No. 24-7-583
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practreeshould be consulted. our findings include interpolation and extrapolation of the
subsurface conditions identified at the exploratory boring andvaialions in the subsurface
conditions may not become evident vrfiil excavation is performed. If conditions encountered
during construction Lppear different from those described in this report, we should be notified
so that re-evaluation of the recomme'lrdations may be made'
This re,port has been prepared for the exclusive use by our clie,lrt 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 teview and
monitor the implementation of our recommendations, and to vetlfy thaltherecommendations
have been appropriately interpreted. Significant design changes may rcqvire additional analysis
or modifications to t5e recommendations presented herein. We recommend on-site observation
of excavations and foundation beaing s?ata andtesting of structural fill by a represantative of
the geotechni cal engineet,
Respectfully Submitted,
Kumar & Associates, Ine.
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Paul J. Graf, StatrEngineer
Reviewed by:
Daniel E. Hardin, P.
PJGlkac
cc: S&S Genqal Renninger (Lf-erurin ser@,s ands eqiil:. qgn)
Kumar & Associates, lnc. o Proiect No. 24-V"583
BORING 1
EL. 8657'
LEGEND
TOPSO|L; SILT, SANDY, FIRM, SLIGHTLY MOIST' BR0WN'
o
SILT AND SAND (ML-SM); INTER-I,AYERED SILVSAND I.AYERS'
SLIGHTLY CALCAREOUS, LOOSE TO MEDIUM DENSE' SLIGHTLY
MOIST, LIGHT BNOWN-TAN.
SANDST0NE BEDR0CK; VERY HARD, SLIGHTLY MO|ST, LIGHT
BROWN.
11 /12
WC=2,1
DD=101
-200=41
5
7 /12
WC=3.6
DD=97 DRIVE SAMPLE, 2-INCH I.D. CALIFORNIA LINER SAMPLE.
FLl
LJ
t!
I-F(L
t!o
10/12
WC=5.8
DD=101
.. r,^DRIVE SAMPLE BLOW C0UNT. INDICATES THAT 11 BL0WS 0Ftt/ tL A i4o-pouND HAMMER FALLING 50 lNcHEs WERE REQUIRED
TO DRIVE THE SAMPLER 12 INCHES.
10
13/12
NOTES
1, THE EXPLORATORY BORING WAS DRILLED ON OCTOBER 9' 2024
WITH A 4-INCH DIAMETER CONTINUOUS FLIGHT POWER AUGER.
2. THE LOCATION OF THE EXPLORATORY BORING WAS MEASURED
APPROXIMATELY BY PACING FROM FEATURES SHOWN ON THE
SITE PLAN PROVIDED.
3. THE ELEVATION OF THE EXPLORATORY BORING WAS OBTAINED
BY INTERPOLATION BETWEEN CONTOURS ON THE SITE PLAN
PROVIDED.
4. THE EXPLORATORY BORING LOCATION AND ELEVATION SHOULD BE
CONSIDERED ACCURATE ONLY TO THE DEGREE IMPLIED BY THE
METHOD USED.
5. THE LINES BETWEEN MATERIALS SHOWN ON THE EXPLORATORY
BORING LOG REPRESENT THE APPROXIMATE BOUNDARIIS BETWEEN
MATERIAL TYPES AND THE TRANSITIONS MAY BE GRADUAL.
6. GROUNDWATER WAS NOT ENCOUNTERED IN THE BORING AT THE
TIME OF DRILLING.
7, LABORATORY TEST RESULTS:
WC = WATER OONTENT (%) (ASTM D 2216);
DD = DRY DENSITY (pcf) (ASTM D 2216);
-2OO = PERCENTAGE iISSIHO NO. 2OO SIEVE (ASTM D 1140).
15
30/o
20
Fis. 2LOG OF EXPLORATORY BORINGKumar & Associates24-7-583
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Geotechnical and Matedals Engineers
and Environmental Scientists
TABLE 1
SUMMARY OF LABORATORY TEST RESULTS
Project No.24-7-583
NATURAL
MOISTURE
CONTENT
I"/ol
NATURAL
DRY
DENSITY
{bcfl
GRADATION
PERCENT
PASSING NO.
200 SIEVE
UNCONFINED
COMPRESSIVE
STRENGTH SOII TYPE
BORING DEPTH
lftl
GRAVEL
(%)
SAND
(%)
LIQUID LIMIT PLASTIC
INDEX
I 2 2.1 101 4l Silt and Sand
4 3.6 97 Sandy Silt
9 5.8 101 Sandy Silt