HomeMy WebLinkAboutSoils Report 09.18.2019K+A
Kumar & Associates, Inc.
Geotechnical and Materials Enginee
and Environmental Scientists
An Employee Owned Company
5020 cu -IV Road 154
Glenwood Sprier s, CO 81601
phone: (9i0) 945-7988
fax: (970) 945a8454
email: kagie, odhis kuniarusa.com
www,kumarussa.co n
Office Locations: Denver (17Q), Parker, Colorado Spring:s, Fort Collins, Glenwood Springs, and Summit County, Colorado
RECEIVED
GARFIELD COUNTY
COMMUNITY DEVELOPMENT
SUBSOIL STUDY
FOR FOUNDATION DESIGN
PROPOSED RESIDENCE
LOT 5, RANCH AT COULTER CREEK
CATTLE CREEK RIDGE ROAD
GARFIELD COUNTY, COLORADO
PROJECT NO. 19-7-494
SEPTEMBER 18, 2019
PREPARED FOR:
NIELS HAGGLUND
368 SOPRIS CIRCLE
BASALT, COLORADO 81621
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TABLE OF CONTENTS
PURPOSE AND SCOPE OF STUDY - 1 -
PROPOSED CONSTRUCTION - 1 -
SITE CONDITIONS - 2 -
FIELD EXPLORATION - 2 -
SUBSURFACE CONDITIONS - 2 -
FOUNDATION BEARING CONDITIONS 3 -
DESIGN RECOMMENDATIONS - 3 -
FOUNDATIONS - 3 -
FOUNDATION AND RETAINING WALLS - 5 -
FLOOR SLABS -6-
UNDERDRAIN SYSTEM - 7 -
SITE GRADING - 8 -
SURFACE DRAINAGE - 8 -
LIMITATIONS - 9 -
FIGURE 1 - LOCATION OF EXPLORATORY BORINGS
FIGURE 2 - LOGS OF EXPLORATORY BORINGS
FIGURE 3 - LEGEND AND NOTES
FIGURE 4 to 8 - SWELL -CONSOLIDATION TEST RESULTS
TABLE 1- SUMMARY OF LABORATORY TEST RESULTS
Kumar & Associates, Inc, ° Project No. 19-7-494
PURPOSE AND SCOPE OF STUDY
This report presents the results of a subsurface study for a proposed residence to be located on
Lot 5, Ranch at Coulter Creek, Cattle Creek Ridge Road. Garfield County, Colorado. The
project site is shown on Figure 1. The purpose of the study was to develop recommendations for
foundation design. The study was conducted in accordance with our proposal for geotechnical
engineering services to Niels Hagglund, dated August 21, 2019.
A field exploration program consisting of exploratory borings was conducted to obtain
information on 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 subsoil conditions
encountered.
PROPOSED CONSTRUCTION
At the time of our study, design plans for the residence had not been developed. The building
location has not been determined but is proposed in the area roughly between the exploratory
boring locations shown on Figure 1. We understand that the ground floor will be slab -on -grade
and the cut depth to bottom of foundation will be 2 to 5 feet below the existing ground surface.
For the purpose of our analysis, foundation loadings for the structure were assumed to be
relatively light and typical of the proposed type of construction.
When building location, grading and loading information have been developed, we should be
notified to re-evaluate the recommendations presented in this report.
Kumar & Associates, Inc.'' Project No. 19-7-494
-2 -
SITE CONDITIONS
The site was vacant at the time of our field work. Most of the building envelope is pasture with
scattered oak brush mainly around the northeast and southwest edges. The building envelope is
located on a broad hilltop with most of the area sloping gently down to the south.
FIELD EXPLORATION
The field exploration for the project was conducted on September 4, 2019. Three exploratory
borings were drilled at the locations shown on Figure 1 to evaluate the subsurface conditions.
The borings were advanced with a 4 inch diameter continuous flight auger powered by a truck-
mounted CME -45B drill rig. The borings were logged by a representative of
Kumar & Associates, Inc.
Samples of the subsoils were taken with 1% 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.
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
The subsurface conditions varied across the site. Graphic logs of the subsurface conditions
encountered at the site are shown on Figure 2. Below about 1 to 3 feet of organic topsoil, the
subsoils consist of very stiff to hard sandy clay and medium dense, clayey gravel containing
cobbles and possible boulders. At a depth of about 19 feet in Boring 2 and 12 feet in Boring 3,
practical drilling refusal was encountered. The clay portions of the soils encountered in this area
typically possess an expansion potential when wetted.
Laboratory testing performed on samples obtained during the field exploration included natural
moisture content and density, percent finer than sand grain size analyses and liquid and plastic
limits. Swell -consolidation testing was performed on relatively undisturbed drive samples of the
clay and fine-grained matrix of the rocky soils. The swell -consolidation test results, presented on
Kumar & Associates, Inc. ' Project No. 19-7-494
3
Figures 4 to 8, indicate low compressibility under relatively light surcharge loading and a low to
high expansion potential when wetted under a constant light surcharge. The laboratory testing is
summarized in Table 1.
No free water was encountered in the borings at the time of drilling and the subsoils were
slightly moist to moist.
FOUNDATION BEARING CONDITIONS
The clay subsoils encountered at the site are expansive. Shallow foundations placed on the
expansive soils similar to those encountered at this site can experience movement causing
structural distress if the clay is subjected to changes in moisture content. A drilled pier
foundation can be used to penetrate the expansive materials to place the bottom of the piers in a
zone of relatively stable moisture conditions and make it possible to load the piers sufficiently to
resist uplift movements. Using a pier foundation, each column is supported on a single drilled
pier and the building walls are founded on grade beams supported by a series of piers. Loads
applied to the piers are transmitted to the underlying rocky soils partially through peripheral
shear stresses and partially through end bearing pressure. In addition to their ability to reduce
differential movements caused by expansive materials, straight -shaft piers have the advantage of
providing relatively high supporting capacity and should experience a relatively small amount of
movement.
As an alternative, where the clay soils are not as deep, shallow spread footing foundations place
on 4 to 5 feet of imported structural fill or the underlying rocky soils may be feasible.
DESIGN RECOMMENDATIONS
FOUNDATIONS - PIERS
Based on the data obtained during the field and laboratory studies, we recommend straight -shaft
piers drilled into the rocky soils be used to support the proposed structure,
The design and construction criteria presented below should be observed for a straight -shaft pier
foundation system:
Kumar & Associates, Inc. " Project No. 194494
4
1) The piers should be designed for an allowable end bearing pressure of 10,000 psf
and an allowable skin friction value of 1,000 psf for that portion of the pier below
about 8 feet.
2) Piers should also be designed for a minimum dead load pressure of 4,000 psf
based o11 pier end area only. If the minimum dead load requirement cannot be
achieved, the pier length should be extended beyond the minimum penetration to
make up the dead load deficit. This can be accomplished by assuming one-half
the allowable skin friction value given above acts in the direction to resist uplift.
3) Uplift on the piers from structural loading can be resisted by utilizing 75% of the
allowable skin friction value plus an allowance for the weight of the pier.
4) Piers should penetrate at least 20 feet or to practical drilling refusal. A minimum
pier length of 20 feet is recommended.
5) Piers should be designed to resist lateral loads assuming a modulus of horizontal
subgrade reaction of 75 tcf in the clay soils. The modulus value given is for a
long, 1 foot wide picr and must be corrected for pier size.
6) Piers should be reinforced their full length with one #5 reinforcing rod for each 16
inches of pier perimeter to resist tension created by the swelling materials.
7) A 4 -inch void form should be provided beneath grade beams to prevent the
swelling soil from exerting uplift forces on the grade beams and to concentrate
pier loadings. A void form should also be provided beneath pier caps.
8) Concrete utilized in the piers should be a fluid mix with sufficient slump so that
concrete will fill the void between the reinforcing steel and the pier hole.
9) Pier holes should be properly cleaned prior to the placement of concrete. Cobbles
and possible boulders were encountered in the soil in some of the borings which
could cause caving and difficult drilling. The drilling contractor should mobilize
equipment of sufficient size to effectively drill through possible coarse soils.
10) Although free water was not encountered in the borings drilled at the site, some
seepage in the pier holes may be encountered during drilling. Dewatering
equipment may be required to reduce water infiltration into the pier holes. If
water cannot be removed prior to placement of concrete, the tremie method
should be used after the hole has been cleaned of spoil. In no case should
concrete be placed in more than 3 inches of water.
Kumar & Associates, Inc. Project No. 19-7494
5
11) Care should be taken to prevent the forming of mushroom -shaped tops of the
piers which can increase uplift force on the piers from swelling soils.
12) A representative of the geotechnical engineer should observe pier drilling
operations on a full-time basis.
FOUNDATION ALTERNATIVE
If the house is located in the area of Borings 2 and 3, it may be possible to place spread footing
foundations which are designed for an allowable soil bearing pressure of 3,000 psf on 4 to 5 feet
of structural fill. The shallow clay soils in Borings 2 and 3 had high plasticity and are potentially
expansive. The structural fill should consist of imported 3/4 -inch road base compacted to at least
98% of the maximum standard Proctor density at a moisture content near optimum. Additional
subsurface exploration and analysis should be performed after the house has been sited.
FOUNDATION AND RETAINING WALLS
Foundation walls and retaining structures which are laterally supported and can be expected to
undergo only a slight amount of deflection should be designed for a lateral earth pressure
computed on the basis of an equivalent fluid unit weight of 60 pcf for backfill consisting of the
on-site clayey soils and 45 pcf for backfill consisting of imported granular materials.
Cantilevered retaining structures which are separate from the residence and can be expected to
deflect sufficiently to mobilize the full active earth pressure condition should be designed for a
lateral earth pressure computed on the basis of an equivalent fluid unit weight of 50 pcf for
backfill consisting of the on-site clay soils and 40 pcf for backfill consisting of imported granular
materials.
All foundation and retaining structures should be designed for appropriate hydrostatic and
surcharge pressures such as adjacent footings, traffic, construction materials and equipment. The
pressures recommended above assume drained conditions behind the walls and a horizontal
backfill surface. The buildup of water behind a wall or an upward sloping backfill surface will
increase the lateral pressure imposed on a foundation wall or retaining structure. An underdrain
should be provided to prevent hydrostatic pressure buildup behind walls.
Backfill should be placed in uniform lifts and compacted to at least 90% of the maximum
standard Proctor density at a moisture content near optimum. Backfill placed in pavement areas
Kumar & Associates, inc. rs' Project No, 19.7-494
6
should be compacted to at least 95% of the maximum standard Proctor density. Care should be
taken not to overcompact the backfill or use large equipment near the wall since this could cause
excessive lateral pressure on the wall. Some settlement of deep foundation wall backfill should
be expected even if the material is placed correctly and could result in distress to facilities
constructed on the backfill.
We recommend imported granular soils for backfilling foundation walls and retaining structures
because their use results in lower lateral earth pressures. Granular materials should be placed up
to within -2 -feet of the ground surface and to a minimum of 3 feet beyond the walls. The granular
backfill behind foundation and retaining walls should extend to an envelope defined as a line
sloped up from the base of the wall at an angle of at least 30 degrees from the vertical. The
upper 2 feet of the wall backfill should be a relatively impervious on-site soil (or a pavement
structure should be provided) to prevent surface water infiltration into the backfill.
Shallow spread footings may he used for support of retaining walls separate from the residence,
provided some differential movement and distress can be tolerated. Footings should be sized for
a maximum allowable bearing pressure of 3,000 psf. The lateral resistance of retaining wall
footings will be a combination of the sliding resistance of the footing on the foundation materials
and passive earth pressure against the side of the footing. Resistance to sliding at the bottoms of
the footings can be calculated based on a coefficient of friction of 0.35. Passive pressure against
the sides of the footings can be calculated using an equivalent fluid unit weight of 325 pcf. The
coefficient of friction and passive pressure values recommended above assume ultimate soil
strength. Suitable factors of safety should be included in the design to limit the strain which will
occur at the ultimate strength, particularly in the case of passive resistance. Fill placed against
the sides of the footings to resist lateral loads should be a nonexpansive granular material
compacted to at least 95% of the maximum standard Proctor density at a moisture content near
optimum.
FLOOR SLABS
Floor slabs present a problem where expansive materials are present near floor slab elevation
because sufficient dead load cannot be imposed on them to resist the uplift pressure generated
when the materials are wetted and expand. We recommend that structural floors with crawlspace
below be used for all floors in the building that will be sensitive to upward movement.
Kumar & Associates, Inc. Project No. 19-7.494
7
Slab -on -grade construction may be used in the shallow expansive clay area provided the risk of
distress is understood by the owner.
We recommend placing at least 5 feet of nonexpansive
structural fill below floor slabs in order to help mitigate slab movement due to expansive soils.
To reduce the effects of some differential movement, nonstructural floor slabs should be
separated from all bearing walls, columns and partition walls with expansion joints which allow
unrestrained vertical movement. Interior non-bearing partitions resting on floor slabs should be
provided with a slip joint at the bottom of the wall so that, if the slab moves, the movement
cannot be transmitted to the upper structure. This detail is also important for wallboards,
stairways and door frames. Slip joints which allow at least 11/z inches of vertical movement are
recommended. Floor slab control joints should be used to reduce damage due to shrinkage
cracking. Joint spacing and slab reinforcement should be established by the designer based on
experience and the intended slab use.
Required fill beneath slabs should consist of a suitable imported granular material such as 3/ -inch
road base, excluding topsoil and oversized rocks. The suitability of structural fill materials
should be evaluated by the geotechnical engineer prior to placement. The fill should be spread in
thin horizontal lifts, adjusted to at or above optimum moisture content, and compacted to 95% of
the maximum standard Proctor density. All vegetation, topsoil and loose or disturbed soil should
be removed prior to fill placement.
The above recommendations will not prevent slab heave if the expansive soils underlying slabs -
on -grade become wet. However, the recommendations will reduce the effects if slab heave
occurs. All plumbing lines should be pressure tested before backfilling to help reduce the
potential for wetting.
UNDERDRAIN SYSTEM
Although groundwater was not encountered during our exploration, it has been our experience in
mountainous areas and where clay soils are present, that local perched groundwater may develop
during times of heavy precipitation or seasonal runoff Frozen ground during spring runoff can
create a perched condition. Therefore, we recommend below -grade construction, such as
crawlspace and basement areas, be protected from wetting by an underdrain system. The drain
should also act to prevent buildup of hydrostatic pressures behind foundation walls.
Kumar & Associates, Inc.Project No. 19-7494
8
The underdrain system should consist of a drainpipe surrounded by free -draining granular
material placed at the bottom of the wall backfill. The drain lines should be placed at each level
of excavation and at least 1 foot below lowest adjacent finish grade, and sloped at a minimum
1% grade to a suitable gravity outlet. Free -draining granular material used in the drain system
should consist of minus 2 inch aggregate with less than 50% passing the No. 4 sieve and less
than 2% passing the No. 200 sieve. The drain gravel should be at least 2 feet deep. Void form
below the grade beams can act as a conduit for water flow. An impervious liner such as 20 mil
PVC may be placed below the drain gravel in a trough shape and attached to the grade beam with
mastic to keep drain water from flowing beneath the grade beam and to other areas of the
building.
SITE GRADING
Fill material used inside building limits and within 3 feet of pavement grade should consist of
nonexpansive, granular material. Fill should be placed and compacted to at least 95% of the
maximum standard Proctor density near the optimum moisture content. Fill should riot contain
concentrations of organic matter or other deleterious substances. The geotechnical engineer
should evaluate the suitability of proposed fill materials prior to placement. In fill areas, the
natural soils should be scarified to a depth of 6 inches, adjusted to a moisture content near
optimum and compacted to provide a uniform base for fill placement.
The natural clay soils encountered during this study will be expansive when placed in a
compacted condition. Consequently, these materials should not be used as fill material beneath
building areas or directly beneath pavement areas. The natural soil can be used for fill material
near the bottom of fills outside building areas.
SURFACE DRAINAGE
The following drainage precautions should be observed during construction and maintained at all
times after the residence has been completed:
1) Excessive wetting or drying of the foundation excavations and underslab areas
should be avoided during construction. Drying could increase the expansion
potential of the clay soils.
2) Exterior backfill should be adjusted to near optimum moisture and compacted to
at least 95% of the maximum standard Proctor density in pavement areas and to at
Kumar & Associates, Inc. Project No. 19.7494
9
least 90% of the maximum standard Proctor density in landscape areas. Free -
draining wall backfill should be capped with about 2 to 3 feet of the on-site soils
to reduce surface water infiltration.
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.
4) Roof downspouts and drains should discharge well beyond the limits of all
backfill.
5) Landscaping which requires regular heavy irrigation and sprinkler heads should
be located at least 10 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 to be different from those described in this report, we should be
notified at once so 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
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 of the recommendations presented herein. We recommend on-site observation
Kumar & Associates, inc. 0 Project No, 19.7.494
-10 -
of excavations, pier hole drilling and foundation bearing strata and testing of structural fill by a
representative of the geotechnical engineer.
Sincerely,
Kumar & Associates, Inc.
Daniel E. Hardin, P.
Reviewed by:�,
4,7�IVALIts"
�-'tom:.... ,•e
0L/
24443 z:
-6% 'j /1 q%/
Steven L. Pawlak, P.E.
DEH/kac
cc: Jess Pedersen (ped arch01,gmail.com)
Kumar & Associates, Inc. 0 Project No.193.494
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�-- _ sir°ss' �-_- U 'iN
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IAC)k' BORING 2 4254;7' 7' - -� 1 l
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rlf cn \ k , \ i,\
i'' LOT 5 5i\
- s=� BORING 3 1 90, 283 sq. ft. , rp.
Ayw ^^ Y
�,, �� 4.36 S acres BORIN. \ I
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29? i 3, W •'_ I N 9a•0-o»,� 25.00' _ \ 1 \
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415.33'
Common I
Open Space
50 0 50 100
APPROXIMATE SCALE -FEET
19-7-494
Kumar & Associates
LOCATION OF EXPLORATORY BORINGS
Fig. 1
w
w
I
0
5
10
-15
20
25
-• 30
BORING 1
26/12
16/12
WC=19.8
DU=100
35/12
WC=8.5
DD=102
-200=15
46/12
22/12
WC=29.0
DD=87
95/12
WC=19.0
DD=101
50/5
BORING 2
18/12
WC=15.2
DD=106
28/12
WC=18.9
DD=107
-200=87
LL=52
P1=32
34/12
WC=9.6
DD=120
16/12
WC=28.7
DD=86
BORING 3
25/12
WC=8.9
DD=108
-200=62
56/12
WC=12.3
-200=36
LL=50
PI=22
50/5
0
5-
10 -
10
15-
20
5-
20
25
30
35 35
19-7-494 19-7-494
Kumar & Associates
LOGS OF EXPLORATORY BORINGS
Fig. 2
LEGEND
.^r
7
1.
/•4
/-4
TOPSOIL; ORGANIC SILTY CLAY, SANDY, SOFT, SLIGHTLY MOIST, DARK BROWN.
CLAY (CL); SANDY WITH GRAVEL, VERY STIFF TO HARD, SLIGHTLY MOIST TO MOIST, MEDIUM
TO HIGH PLASTICITY, BROWN.
BASALT GRAVEL (GC) WITH COBBLES, PROBABLE BOULDERS, IN SANDY CLAY WITH SILT
MATRIX, DENSE, SLIGHTLY MOIST, GRAY BASALT WITH WHITE CALCAREOUS MATRIX SOILS.
DRIVE SAMPLE, 2—INCH I.D. CALIFORNIA LINER SAMPLE.
DRIVE SAMPLE, 1 3/8—INCH I.D. SPLIT SPOON STANDARD PENETRATION TEST.
26/12 DRIVE SAMPLE BLOW COUNT. INDICATES THAT 26 BLOWS OF A 140—POUND HAMMER
FALLING 30 INCHES WERE REQUIRED TO DRIVE THE SAMPLER 12 INCHES.
DEPTH AT WHICH BORING CAVED.
PRACTICAL AUGER REFUSAL.
NOTES
1. THE EXPLORATORY BORINGS WERE DRILLED ON SEPTEMBER 4, 2019 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 02216);
DD = DRY DENSITY (pcf) (ASTM D2216);
—200= PERCENTAGE PASSING NO. 200 SIEVE (ASTM 01140);
LL = LIQUID LIMIT (ASTM D4318);
PI = PLASTICITY INDEX (ASTM D4318).
19-7-494
Kumar & Associates
LEGEND AND NOTES
Fig. 3
1
—2
Z
0
1-
—4
Thom toot mulls appy only to Una
.0 1whd,;r tn165
u nal 1» rup o x 41. aa:a.pirfm
fud, wtlhaut 11N mitten app,GYal of
Kvmor and N.o[kln. taa. S.
Cana ldo* helico omfotm*d In
eeuyana...th ASTU 0.4518,
TSAMPLE OF: Sandy Silty Clay
FROM: Boring 1 0 5'
' WC = 19.8 %, DD = 100 pcf
NO MOVEMENT UPON
WETTING
1.0 APPLIED PRESSURE -- KSF 10 100
19-7-494
Kumar & Associates
SWELL -CONSOLIDATION TEST RESULTS
Fig. 4
8740A-ai r 08.2vvg
3
2
J
-J
Lj
N 1
CONSOLIDATION
CONSOLIDATION - SWELL
0
—1
— 2
— 3
0
— 2
SAMPLE OF: Sandy Clay
FROM: Boring 1 ® 20'
WC = 29.0 %, DD = 87 pcf
EXPANSION UNDER CONSTANT
PRESSURE UPON WETTING
1.0 APPLIED PRESSURE — KSF 10 100
SAMPLE OF: Sandy Silt
FROM: Boring 1 ® 25'
WC = 19.0 %, DD = 101 pcf
Thole raeulle Dopy any tv She
eumples te,Wd. Tha Stith.; moor!
Oka not twe r•prpdyppd, mtnpl in
full, rllhput the rlflsn opprorol of
Komar Ind Aeecektle. STlR!
Coin dotivn hstln perlprmed in
cordw,ce wflh ASSY D-4 4 .
EXPANSION UNDER CONSTANT
PRESSURE UPON WETTING
1.0 APRUED PRESSURE — KSF 10 10D
19-7-494
Kumar & Associates
SWELL—CONSOLIDATION TEST RESULTS
Fig. 5
8
7
6
4
w
3
CONSOLIDATION
3
2
0
—2
3
SAMPLE OF: Sandy Clay
FROM: Boring 2 0 2.5'
WC = 15.2 %, DD = 106 pcf
Thea. 0.16. tO the
VW
..falaml, talaatd
hanonott TTwIriN,tI:anp
l
fn
without the written approval N
Coon f and Aetrerateo, illi.orin
aaonodon. with D-4546.
EXPANSION UNDER CONSTANT
PRESSURE UPON WETTING
1.0 APPLIED PRESSURE - KSF t0 10D
19-7-494
Kumar & Associates
SWELL -CONSOLIDATION TEST RESULTS
Fig. 6
'm.6'G'an4'9tlyriPd—Ud •a Dt1.0.0
CONSOLIDATION - SWELL
2
i
0
—1
—2
—3
—4
SAMPLE OF: Sandy Clay
FROM: Boring 2 ® 10'
WC = 9.6 %, DD = 120 pcf
Theca laal mono tippy ordy !a 1ha
a9m.oloa ltatad- 1M ladlnq impart
OW no! to raprodoceb, seEapl 1n
tud, yho61 Sha .Fitton epprwul o/
Kumar and Meoc!o!.o IM. SWOU
Coneol[dailon (dollop poolarmed In
occordann .!h A h4 C-4346.
- EXPANSION UNDER CONSTANT
PRESSURE UPON WETTING
1.0 APPLJED PRESSURE — KSF 10 100
19-7-494
Kumar & Associates
SWELL—CONSOLIDATION TEST RESULTS
Fig. 7
5t
.. 4
CONSOLIDATION -
2
}
0
—3
These Wel r p' uflI opn j I 1M
:Zell be re radials!. i0S In
Wd, sihoaf Sha wrtapproa
of
Wmbr and NocalWEnc. S.e
inlna porlorriroid
aewith
ASTM C-4618.
In
SAMPLE OF: Sandy Clay
FROM: Boring 2 0 15'
WC = 28.7 %, DD = 86 pcf
EXPANSION UNDER CONSTANT
PRESSURE UPON WETTING
1.0 APPLIED PRESSURE — 1CSF
10 100
19-7-494
Kumar & Associates
SWELL—CONSOLIDATION TEST RESULTS
Fig. 8
1 (+A Geotechnical and fula3erials Er�lneers
and Environmental Scierstists
TABLE 1
SUMMARY OF LABORATORY TEST RESULTS
Prosect No. 19-7-494
SAMPLE LOCATION
NATURAL
MOISTURE
CONTENT
(A)
NATURAL
DRY
DENSITY
(Pet)
GRADATION
PERCENT
PASSING NO.
200 SIEVE
ATTERBERG LIMITS
SWELL
PRESSURE
(Pst)
SWELL
SOIL TYPE
BORING
DEPTH
(ft)
GRAVEL
(°A)
SAND
PA)
LIQUID LIMB
(°A)
PLASTIC
INDEX
(%)
1
5
19.8
100
--
--
Sandy Silty Clay
10
8.5
102
15
Clayey Sand
20
29.0
87
15,000
2.7
Sandy Clay
25
19.0
101
9,000
0.6
Sandy Silt
2
21h
15.2
106
20,000
7.7
Sandy Clay
5
18.9
107
87
52
32
Sandy Clay
10
9.6
120
3,000
0.9
Sandy Clay
15
28.7
86
20,000
5.2
Sandy Clay
3
21
8.9
108
62
-
Sandy Silty Clay
5
12.3
36
50
22
Clayey Sand with Gravel
w
From: Dan Hardin dhardin@kurnamsa.com
Subject: Additional borings at Lot 5, Coulter Creek
Date• October 30, 2019 at 5:58 PM
To: pedarch@gmail.com
Cc: Niels hagglund.n@comcast.net
Jess,
Here is what I came up with.
Bldg Area NW Corner SW Corner SE corner NE Corner
Grd Elev. 7456' 7454' 7456' 7458'
Depth to Rocks 6' 8.5' 7' 6'
Est. Elev. Of 7450' 7445.5' 7449' 7452'
Top of Rocky
Layer
Main Floor Elevation is 7456' Bottom of Footing Elevation is 7450'?
Note: Grd elevation is based on topographic lines on plan provided.
Looks like footing grade will be close to top of rocky layer except at SW corner where it is 4.5 feet
lower.
Should be feasible to put in up to 2 feet of fill below footings where needed. Could drop footing
elevation a few feet in SW corner so that fill depth below footing is not more than 2 feet. The
purpose of limiting the fill depth is to reduce settlement risk.
Could we put in 2.5 or 3 feet of fill? Probably.
Dan Hardin, P.E.
Associate Principal
30
1 X89 2 V1
C: (970) 379-2329
V vll-r--T _S -t O
0: (970) 945-7988
E: dhardin@kumarusa.com
Kumar & Associates; Inc,
5020 County Road 154
Glenwood Springs, Colorado 81601
www.kumarusa.r
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