HomeMy WebLinkAboutSubsoils Report for Foundation DesignlGrtfiffilfi#fffffirivi*'"5020 County Road 154
Glenwood Springs, CO 81601
phone: (970) 945-7988
fax: (970) 945-8454
email : kaglenwood@kumarusa.com
An Employec Ownod Compcny www.kumarusa.com
Offrce Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
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'{,:ti,SUBSOIL STUDY
F'OR FOUNDATION DESIGN
PROPOSED RESIDENCE
LOLT 28, FIRST EAGLE POINT
239 EAGLE RIDGE DRIVE, PARACHUTE
GARFIELD COUNTY, COLORADO
PROJECT NO.25-7-112
FEBRUARY 6,2025
PREPARE,D FOR:
URIEL MELLIN
144 CLIFFROSE WAY
GLENWOOD SPRTNGS, COLORADO 81601
u riel. m ellin@hotmail.com
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TABLE OF CONTENTS
PURPOSE AND SCOPE OF STUDY
PROPOSED CONSTRUCTION ..
SITE CONDITIONS
FIELD EXPLORATION
SUBSURFACE CONDITIONS .......
FOIINDATION BEARING CONDITIONS
DESIGN RECOMMENDATIONS ..
FOUNDATIONS
FLOOR SLABS
I-INDERDRAIN SYSTEM
SURFACE DRAINAGE
LIMITATIONS
FIGURE I - LOCATION OF EXPLORATORY BORINGS
FIGURE 2 - LOGS OF EXPLORATORY BORINGS
FIGURES 3 _ LEGEND AND NOTES
FIGURES 4 and 5 - SWELL-CONSOLIDATION TEST RESULTS
FIGURE 6 _ GRADATION TEST RESULTS
TABLE 1- SUMMARY OF LABORATORY TEST RESULTS
1
1
1
I
a
a
2
2
J
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4
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Kumar & Associates, lnc. @ Project No.25-7-112
PURPOSE AND SCOPE OF STUDY
This report presents the results ofa subsoil study for a proposed residence to be located at
239 Eagle Ridge Drive, Lot28, First Eagle Point, Garfield County, Colorado. The project site
is shown on Figure l. The purpose of the study was to develop recommendations for the new
foundation and pavement design. The study was conducted in accordance with our agreement
for geotechnical engineering services to Uriel Mellin, dated January 8,2025.
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 analyzedto develop recommendations for foundation types, depths and allowable
pressures for the proposed residence. 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 over a crawlspace. The
attached garage will have a slab-on-grade floor. 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 site is a vacant lot vegetated with grass and weeds. The site slopes slightly down to the
northwest at about 3 percent grade within the building envelope.
FIELD EXPLORATION
The field exploration for the project was conducted on December 14,2024. 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-458 drill rig. The borings were logged by a representative of Kumar &
Associates,Inc.
Samples of the subsoils were taken with I% 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-l586
Kumar & Associates, lnc. @ Project No. 25-7-112
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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
borings were drilled in the northwest and southeast parts of the lot. Below a thin topsoil layer,
the subsoils consist of about 2 to 4 feet stiff, sandy silt and sandy silty clay. The silt and clay
soils were underlain at depth by relatively dense, clayey sandy gravel. The dense gravel was
encountered at 6% feet in Boring 1 and at 2 feet in Boring 2. Refusal to auger drilling was
encountered at7 to 8 feet deep.
Laboratory testing performed on samples obtained from the borings included natural moisture
contento density and gradation analyses. Results of swell-consolidation testing performed on
a relatively undisturbed drive sample of the silt soils, presented on Figure 3 indicate low to
moderate compressibility under conditions of loading and compressibility when wetted. The
laboratory testing is summarizedin Table 1.
No free water was encountered in the borings at the time of drilling and the subsoils were moist.
F'OUNDATION BEARING CONDITIONS
The natural soils at footing grade will consist of medium stiff to stiff, sandy silty clay or
relatively dense silty sand. Spread footing foundations designed as recommended below should
be suitable for support of the proposed residence.
DESIGN RECOMMENDATIONS
FOUNDATIONS
Considering the subsurface conditions encountered in the exploratory borings and the nature of
the proposed construction, we recommend the residence be supported on spread footings bearing
on the natural clay or silty sand soils.
The design and construction criteria presented below should be observed for a spread footing
foundation system.
l) Footings placed on the undisturbed natural granular soils should be designed for
an allowable bearing pressure of 1,500 psf. Based on experience, we expect
settlement of new footings designed and constructed as discussed in this section
will be about I inch or less.
2) Footings should have a minimum width of 18 inches for continuous walls and
2 feet for isolated pads.
Kumar & Associates, lnc. @ Project No. 25-7-112
-3-
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.
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 be designed for a lateral
earth pressure computed on the basis of an equivalent fluid unit weight of at least
50 pcf for backfill consisting of the on-site fine-grained soils.
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 clay and silt
soils. The exposed soils in footing area should then be moistened and compacted.
A representative of the geotechnical engineer should observe all footing
excavations prior to concrete placement to evaluate bearing conditions.
4)
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 50% retained on the No. 4 sieve
and less than2?o passing the No. 200 sieve.
All fill materials for support of floor slabs should be compacted to at least 95Yo of maxlmum
standard Proctor density at a moisture content near optimum. Required fill can consist of
imported granular soils such as3/+-inch road base.
UNDERDRAIN SYSTEM
Although free water was not encountered during our exploration, it has been our experience
in mountainous areas that local perched groundwater can develop during times of heavy
precipitation or seasonal runoff. Frozen ground during spring runoff can also create a perched
condition. We recommend below-grade construction, such as retaining walls and crawlspace
areas, be protected from wetting and hydrostatic pressure buildup by an underdrain system.
The drains should consist of drainpipe placed in the bottom of the wall backfill surrounded above
the invert level with free-draining granular material. The drain should be placed at each level of
excavation and at least I foot below lowest adjacent finish grade and sloped at a minimum lo/oto
5)
6)
Kumar & Associates, lnc. @ Project No. 25-7-112
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a suitable gravity outlet or drywell. Free-draining granular material used in the underdrain
system should contain less than 2Yopassing the No. 200 sieve, less than 50%o passing the No. 4
sieve and have a maximum size of 2 inches. The drain gravel backfill should be at least I%feet
deep.
SURFACE DRAINAGE
The following drainage precautions should be observed during construction and maintained at all
times after the building renovations have been completed:
l) 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 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. Free-draining wall backfill 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.
LIMITATIONS
This study has been conducted in accordance with generally accepted geotechnical engineering
principles and practices in this arca atthis 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.
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
Kumar & Associates, lnc. @ Project No. 25-7-112
5
monitor the implementation of our recommendations, and to veriry 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,
Kuman & A**ocintes,
Daniel E. Hardin, P
Reviewed by:
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Steven L. Pawlak,P.E.
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APPROXIMATE SCALE-FEET
25-7 -1 12 Kumar & Associates LOCATION OF EXPLORATORY BORINGS Fig. 1
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BORING 1 BORING 2
0 0
4s/12
WC=6.5
DD=1 04 so/s
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5
34/12
WC=10.0
DD=82
so/6
5
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COMBINED
10 10+4=31
-2QQ=46
Fig. 225-7-112 Kumar & Associates LOGS OF EXPLORATORY BORINGS
*
LEGEND
TOPSOIb ORGANIC SANDY SILT, SCATTERED BASALT FRAGMENTS, FIRM, MOIST, BROWN.
SILT (ML); SANDY TO VERY SANDY, SCATTERED BASALT FRAGMENTS, STIFF, SLIGHTLY MOIST,
LIGHT BROWN.
SAND AND CLAY (SC-CL); S|LTY, STIFF TO MEDIUM DENSE, SLIGHTLY MOIST, WHIrE
BASALT GRAVEL AND COBBLES; IN CALCAREOUS SANDY SILT MATRIX, DENSE, SLIGHTLY MOIST,
LIGHT BROWN TO WHITE.
DRIVE SAMPLE, 2-INCH I.D. CALIFORNIA LINER SAMPLE.
i DRTVE SAMPLE, 1 3,/8-|NCH t.D. SPLIT SPOON STANDARD PENETRATION TEST
lE 116 DRIVE SAMPLE BLOW COUNT. INDICATES THAT 45 BLOWS OF A 140-POUND HAMMER+r/ tz FALLTNG 50 TNcHES WERE REQUTRED To DRtvE THE SAMpLER 12 tNcHES.
t PRACTICAL AUGER DRILLING REFUSAL WHERE SHOWN ABOVE BOTTOM OF BORING, INDICATES
THAT MULTIPLE ATTEMPTS WHERE MADE TO ADVANCE THE HOLE.
NOTES
1 THE EXPLORATORY BORINGS WERE DRILLED ON JANUARY 14,2025 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.
5. 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 D2216);
DD = DRY DENSITY (PCt) (ISTU D2216);
+4 = PERCENTAGE RETAINED ON NO. 4 SIEVE (ASTM D6915);
-2OO= PERCENTAGE PASSING NO. 2OO SIEVE (ASTM D1140).
25-7-112 Kumar & Associates LEGEND AND NOTES Fig. 5
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SAMPLE OF: Sondy Silt
FROM:Boringl@2'
WC = 6.5 %, DD = 104 pcf
ADDITIONAL COMPRESSION
UNDER CONSTANT PRESSURE
DUE TO WETTING
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EmpL. tadad. lt t-u{ EFrtJEf not b. dFduc.d, .€pt ln
lltl, rltbd tfia rrltt n oMl ot
Kumr ond Atdob, lE. stll
Corfildalbn iaaum tsrtormad hM rh ASil B-{5{.
1
0
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APPUED PRESSURE - KSF t0 100
SWELL-CONSOLIDATION TEST RESULTS Fig. 425-7-112 Kumar & Associates
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-16
-18
I.O APPUED PRESSURE - KSF t0 t00
SAMPLE OF: Sondy Silty Cloy
FROM:Boringl@4'
WC = 10 %, DD = 82 pcl
{)
ADDITIONAL COMPRESSION
UNDER CONSTANT PRESSURE
DUE TO WETTING
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lHuilbopDt6ybft
EmpL. t!d.d. TN t aum Eport,El not b. nDrodu€d, aEpt h
tull, rthout fr rrltLn .ffi| otxlmr ond lsclct-. lF, snll
CorDfdothn tdtm F fmd h*6rdori6 rtlh lSlI D-,15,13,
Kumar & Associates SWELL.CONSOLIDATION TEST RESULTS Fig. 525-7-112
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t00
90
to
70
60
50
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to
xt
to
o
HYDROIIETER ANALYSIS SIEVE ANALYSIS
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IN
SAND GRAVEL
FINE MEDTUM lCOmSe FINE COARSE
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50
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CLAY TO SILT COBBLES
GRAVEL 51 T SAND 23 X
UQUID UMIT - PI.ASTICIW INDEX
SAMP]I OF: V.ry Sllty Sond ond Gruvcl
SILT AND CLAY 16 X
FROII: Borlng 2 o 2' & 4' (Combln.d)
lar
Th.r illt ilulb opply only lo lh.
romplG uhloh wrn l.rl.d. Thrlslln! nporl iloll not b. nprcducrd,
oxocpl ln full, ullhoul lh. urlll.n
opprcYql of Kunqr & Asslolrar, lno,Sld. qnqltdt i.dlng Ir prrtom.d lnqo@rtsnc! vlth ASTII D69lt, ASTII D7928,
ASnr Cl56 and,/or ASIII Dll/ll,,
25-7-112 Kumar & Associates GRADATION TEST RESULTS Fig. 6
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TABLE 1
SUMMARY OF LABORATORY TEST RESULTS
Project No.25-7-112
SOIL TYPE
Sandy Silt
Sandy Silt and Clay
Very Silty Sand and Gravel
UNCONFINED
COMPRESSIVE
STRENGTH
(osfl
ATTERBERG LIMITS
PLASTIC
INDEX
Iolol
LIQUID LIMTT
Iolol
PERCENT
PASSING NO,
200 sIEVE
46
GRADATION
SAND
l:/"1
23
GRAVEL
f/")
31
NATURAL
DRY
DENSITY
{ocf)
104
82
NATURAL
MOISTURE
CONTENT
Iolol
6.5
10.0
SAMPLE LOCATION
DEPTH
{ffl
2
4
2 &.4
combined
BORING
I
2