HomeMy WebLinkAboutSubsoils Report for Foundation DesignKt f#ffiffi;x'l-'*
An Employcs Srcncd Cowrpony
5020 Countl'Road 154
Glenwood Springs, CO 81601
phone: (970) 945-7988
fax: (970) 945-8454
email : kaglenwood@kumarusa.com
rnr,l.r..k umat u sa. com
Offtce I-ocations: Denver (IIQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
SUBSOIL STUDY
FOR FOTINDATION DESIGN
PROPOSED RESIDENCE
20 ROAN CREEK DRIVE
LOT 2, FILING 1, BATTLEMENT CRDEK VILLAGE
BATTLEMENT MESA, COLORADO
PROJECT NO.24-7-442
AUGUST 15,2024
PREPARED FOR:
BRAD SKINNER
440 EAST 12TH STREET
RIFLE, COLORADO 81650
bskinneroft)smail.com
TABLE OF CONTENTS
PURPOSE AND SCOPE OF STUDY
PROPOSED CONSTRUCTION
SITE CONDITIONS
FIELD DGLORATION
SUBSURFACE CONDITIONS
DESIGN RECOMMENDATIONS
FOI.INDATIONS
FLOOR SLABS
LINDERDRAIN SYSTEM ........
SURFACE DRAINAGE
LIMITATIONS
FIGURE 1 - LOCATION OF DGLORATORY BORING
FIGURE 2 - LOG OF E)GLORATORY BORING
FIGURE 3 - SWELL-CONSOLIDATION TEST RESULTS
TABLE I _ SUMMARY OF LABORATORY TEST RESULTS
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Kumar & Associates, lnc. o Project No. 24.7-4n
PURPOSE AND SCOPE OF STUDY
This report presents the results ofa subsoil study for a proposed residence to be located at
20 Roan Creek Drive, Lot 3 Filing l, Battlement Creek Village, Battlement Mesa, Colorado.
The project site is shown on Figure l. 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 Tyler Miles dated Jvly 23,2024.
An exploratory boring was drilled 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 residence will be a one-story wood frame structure with an attached garage.
Ground floor will be wood frame over a crawlspace with slab-on-grade floor in the garage.
Grading for the structure is assumed to be relatively minor with cut depths between about 3 to
5 feet. We assume relatively light foundation loadings, typical of the proposed type of
construcflon
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 site is currently a vacant lot vegetated with weeds and sagebrush. The lot slopes down to
the northeast at 5o/oto lUYo grade.
FIELD EXPLORATION
The field exploration for the project was conducted on August 6,2024. One exploratory boring
was drilled at the locations shorm on Figure 1 to evaluate the subsurface conditions. The boring
was 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 withl% 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-1586
Kumar & Associatee , lnc. @ Project No. 24"7-M2
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 Log of Exploratory Boring, Figure 2. The samples were returned to our laboratory
for review by the project engineer and testing.
SI]BSURFACE CONDITIONS
Graphic logs of the subsurface conditions encountered at the site are shown on Figure 2. The
subsoils consist ofabout Yzfoot oftopsoil, consist ofabout llYzfeet ofsandy silt overlying
basalt gravel, cobbles and boulders in a sandy silt matrix. 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 at 16% feet.
Laboratory testing performed on samples obtained from the boring included natural moisture
content and gradation analyses. Results of a consolidation test performed on a small diameter
drive sample (minus 2-inchfraction) of the sandy silt subsoils are shown on Figure 3.
No free water was encountered in the boring at the time of drilling and the subsoils were slightly
moist.
DESIGN RECOMMENDATIONS
FOI.INDATIONS
Considering the subsurface conditions encountered in the exploratory boring and the nature of
the proposed construction, we recommend the residence be founded with spread footings bearing
on the natural granular soils.
The design and construction criteria presented below should be observed for a spread footing
foundation system.
l) Footings placed on the undisturbednatural granular soils should be designed for
an allowable bearing pressure of 1,500 psf. Based on experience, we expect
settlement of footings designed and constructed as discussed in this section will
be about I inch or less.
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
area.
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.
Kumar & Associates, lnc. @ Project No. 2+7-U2
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Foundation walls acting as retaining structures should also be designed to resist
lateral earth pressures corresponding to an equivalent fluid unit weight of at least
50 pcL
All existing fill, topsoil and any loose or disturbed soils should be removed and
the footing bearing level extended down to the relatively stiff natural granular
soils. The exposed soils 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.
6)
FLOOR SLABS
The natural on-site soils, exclusive of topsoil, are suitable to support lightly 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 basement level slabs to facilitate drainage. This
material should consist of minus 2-inch aggregate with at least 50Vo retained on the No. 4 sieve
and less than l5o/o passing the No. 200 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. Required fill can consist of the
on-site granular soils devoid ofvegetation, topsoil and oversized rock.
I.]NDERDRAIN SYSTEM
An underdrain system should not be needed for the proposed slab-on-grade construction.
SURFACE DRAINAGE
The following drainage precautions should be observed during construction and maintained at all
times after the residence 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 95%o 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
awav from the ln directions. We recommend a minimum
slope of l2 inches in the first 10 feet in unpaved areas and a minimum slope of
3 inches in the first 10 feet in paved areas.
Kumar & Associates, lnc. o Project No. 24,7-442
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4)Roof downspouts and drains Should discharge well beyo'nd the limits of all
backfill.
LIMITATIONS
This study has been conducted in accordance with generally accepted geotec"hnical engineering
principles and practices in this are* at this time. We make no warranty either express or implied.
The conclusions and recommendations submitted in this report are based upon the data abtained
from the exploratory borings drilled at the locations indicated on Figute 1, the proposed t5rpe of
construction and our experience in the area. Our serviccs do not include determining the
presenc€, prevention orpossibility of mold or other biological contaminnnts (MOBC) developing
in the future. lf the client is concemed about MOBC, then a professional in this special field
of practice should be consulted, Our findings include interpolation and exkapolation of the
subsurface conditions identified at the exploratory borings lpits and variaticms in the subsurface
conditions may not become evident until excavalion is performed. If conditions encounfered
during construction appear different from those described in this r€port, we should be notified
so that re-evaluation of the recommendations may be made.
This report has been preparecl for the exclusive use by our client for desiggr purposss. 'We are
not responsible for technical interpretations by others of our infonnation. As the project evolves,
we should provide continued sonsultatior and field ss{vices during construction to review and
monitor the implementation of our reconrmendations, and to vsriry that the recommendations
have been appropriately interpreted. Significant tlesign changes may require additional analysis
or modifications to the recommendations presented herein. We recommend on-site observation
ofexcavations and foundation bearing sffata and testing ofstructural fill by a representative of
the geotechnical engineer.
Respectfu lly Submitted,
Humsr & As*cclateu, trnc.
Daniel E. Har"din, P.E.
Reviewed by:
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Steven L. Pawlak, P.E.
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RANCH CREEK DRIVE
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Fig. 1LOCATION OF EXPLORATORY BORING24-7-442 Kumar & Associates
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BORING 1 LEGEND
T0PS0llj ORGANIC SANDY SILT, FlRll, SLIGHTLY MO|ST, BR0WN
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25/12
WC=3.6
DD= 1 05
-200=76
srLT (ML);
SLIGHTLY
SANDY, SI.JGHTLY CALCAREOUS, STIFF TO HARD,
TIOIST, LIGHT BROWN,
5
11/12
WC=3,1
DD=99
BASALT GRAVEL AND COBBI.ES IN SANDY SILT MATRIX, MEDIUII
DENSE TO DENSE, SUGHTLY MOIST, BROWN.
DRIVE SAMPLE, 2-INCH I.D. CAUFORNIA UNER SAMPII.
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s4/12
WC=6.3 I DRTVE SAMPII, 1 5/8-|NCH t.D. SpLrT Sp00N STANDARD
PENETRATION TEST.
DD= I 01
-200=68 1q,711DRlVE SAMPLE BLOIV COUNT. INDICATES THAT 25 BL0WS 0F
140-POUND HAMMER FATUNG 50 INCHES WERE REQUIRED
TO DRIVE THE SAMPLER 12 INCHES.
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27/6,3o/3
NOTES
1 THE EXPLORATORY BORING WAS DRILI.ID ON AUGUST 6,2021
WITH A ,I-INCH DIAMETER CONTINUOUS FUGHT POWER AUGER.
20
2. THE LOCATION OF THE EXPLORATORY BORING WAS MEASURED
APPROXIMATELY BY PACING FROTI FEATURES SHOWN ON THE
SITE PLAN PROVIDED.
3. THE ETTVATION OF THE EXPLORATORY BORING WAS MEASURED
AT 5.8 FEET HIGHER THAN MANHOI..E RIM LOCATED IN RANCH
CREEK DRIVE NORTHEAST OF SITE. THE LOG OF THE
EXPLORATORY BORING IS PLOTTED TO DEPTH.
1. THE EXPLORATORY BORING LOCATION SHOULD BE CONSIDERED
ACCURATE ONLY TO THE DEGREE IMPUED BY THE I4ETHOD USED.
5. THE LINES BETWEEN MATERIALS SHOWN ON THE EXPLORATORY
BORING LOG REPRESENT TI{E APPROXIMATE BOUNDARIES BEnYEEN
MATERIAL TIfPES AND THE TRANSITIONS UAY BE GRADUAL.
6. GROUNDWATER WAS NOT ENCOUNTERED IN THE BORING AT THE
TIIIE OF DRILUNG.
7. LABORATORY TEST RESULTS:
WC = WATER CONTENT (X) (ASTM D 2216);
DD = DRY DENSITY (pct) (sru D 2216);
-2OO = PERCENTAGE PASSING NO. 2OO SIEVE (ASTM D 1140).
24-7-442 Kumar & Associates LOG OF EXPLORATORY BORING Fig. 2
SAMPLE OF: Sondy Silt
FROM:BoringlO4'
WC = 5.1 ?6, DD = 99 pof
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ADDITIONAL COMPRESSION
UNDER CONSTANT PRESSURE
DUE TO WETTING
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24-7-442 Kumar & Associates SWELL-CONSOLIDATION TEST RESULT Fig. 5
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BORING
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DEPTH
SAIIPLE LOCATION
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3.1
3.6
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NATURAL
MOISTURE
CONTENT
101
99
105
NATURAI-
DRY
DENSITY
(ncf,
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GRAVEL SAND
P/"1
GRADATION
68
76
PERCENT
PASSING NO.
2m $EVE
Sandy Silt
Sandy Silt
Sandy Silt
LIQUID LI]IIIT s0tLPLASTIC
INDEX
UNCONFINED
COMPRESSIVE
STRENGTH
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TABLE 1
SUMMARY OF LABORATORY TEST RESULTS
No.24-l-442