HomeMy WebLinkAboutSoils Report 01.20.2020K+A
Komar & Associates, Inc."'
Geotechnical and Materials Engineers
and Environmental 5dertis!s
5020 County Road 154
Glenwood Springs, CO 81601
phone: (970) 945-7988
fax: (970) 945-8454
email: kaglenwoodfuikuma usa.com
An Employee Owned Company www.kumarusa.com
Office Locations: Denver (1-1(J, Parker, Colorado Smogs, Fors Collins, Glenwood Springs, and Summit County, Colorado
SUBSOIL STUDY
FOR FOUNDATION DESIGN
PROPOSED RESIDENCE
LOT 55, CERISE RANCH
22 SUNFLOWER LOOP
GARFIELD COUNTY, COLORADO
PROJECT NO. 20-7-108
JANUARY 20, 2020
PREPARED FOR:
ALLYSON DECATI,TR
181 COYOTE CIRCLE
CARBONDALE, COLORADO 81623
alivson(a)decatu nviiisie.com
TABLE OF CONTENTS
PURPOSE AND SCOPE OF STUDY - I -
PROPOSED CONSTRUCTION - 1
SITE CONDITIONS - 1 -
SUBSIDENCE POTENTIAL - 2 -
FIELD EXPLORATION - 2 -
SUBSURFACE CONDITIONS - 3 -
FOUNDATION BEARING CONDITIONS - 3 -
DESIGN RECOMMENDATIONS - 4 -
FOUNDATIONS - 4 -
FOUNDATION AND RETAINING WALLS - 5 -
FLOOR SLABS - 6 -
UNDERDRAIN SYSTEM - 6 -
SURFACE DRAINAGE - 7 -
LIMITATIONS - 8 -
FIGURE 1 - LOCATION OF EXPLORATORY BORINGS
FIGURE 2 - LOGS OF EXPLORATORY BORINGS
FIGURE 3 - LEGEND AND NOTES
FIGURES 4 & 5 - SWELL -CONSOLIDATION TEST RESULTS
FIGURE 6 GRADATION TEST RESULTS
TABLE 1- SUMMARY OF LABORATORY TEST RESULTS
Kumar & Associates, Inc. ® Project No. 20-7-100
PURPOSE AND SCOPE OF STUDY
This report presents the results of a subsoil study for a proposed residence to be located on
Lot 55, Cerise Ranch, 22 Sunflower Loop, 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 general accordance with our agreement for geotechnical
engineering services to Allyson Decatur dated January 13, 2020.
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 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
At the time of our study, design plans for the residence had not been developed. The building is
proposed in the upper, northern part of the building envelope area shown on Figure, 1. Ground
floors could be structural floor above crawlspace or slab -on -grade. A basement level is being
considered. We assume excavation for the building will have a maximum cut depth of one level,
about 10 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_
SITE CONDITIONS
The lot was vacant with a shallow snow cover at the time of our field exploration. Several
abandoned drainage ditches across the lot. The terrain is steeply sloping down to the south on
the northern portion of the lot and flattens to a gentle slope across the building envelope. The
Kumar & Associates, Inc. ® Project No. 20-7-108
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site is vegetated with grass and weeds in the flat building area, cottonwoods at the toe of the
steep slope, and juniper and pine trees on the steep slope. Several basalt boulders, up to
approximately 5 feet in size, were observed on the steep slope. Two-story single-family
residences are to the northeast, south, and east, Sunflower Loop is to the east, and vacant land is
to the west and north.
SUBSIDENCE POTENTIAL
Bedrock of the Pennsylvanian age Eagle Valley Evaporite underlies Cerise Ranch. These rocks
are a sequence of gypsiferous shale, fine-grained sandstone and siltstone with some massive beds
of gypsum and limestone. There is a possibility that massive gypsum deposits associated with
the Eagle Valley Evaporite underlie portions of the lot. Dissolution of the gypsum under certain
conditions can cause sinkholes to develop and can produce areas of localized subsidence.
Sinkholes have been observed scattered throughout this part of the Roaring Fork River valley.
Sinkholes were not observed in the immediate area of the subject lot. No evidence of cavities
was encountered in the subsurface materials; however, the exploratory borings were relatively
shallow, for foundation design only. Basedonour present knowledge of the subsurface
conditions at the site, it cannot be said for certain that sinkholes will not develop. The risk of
future ground subsidence on Lot 55 throughout the service life of the proposed residence, in our
opinion, is low; however, the owner should be made aware of the potential for sinkhole
development. If further investigation of possible cavities in the bedrock below the site is desired,
we should be contacted.
FIELD EXPLORATION
The field exploration for the project was conducted on January 14, 2020. 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 a truck-
mounted CME 45B drill rig. The borings were logged by a representative of Kumar &
Associates.
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.
Kumar & Associates, Inc. ® Project No. 20-7-108
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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
subsoils consist of about a Vz foot of topsoil overlying medium stiff to stiff, sandy to very sandy
clay and silt with scattered cobbles and gravel zones, underlain by dense, silty sand and gravel
with cobbles. Drilling in the dense granular soils with auger equipment was difficult due to the
cobbles and possible boulders and drilling refusal was encountered in the deposit.
Laboratory testing performed on samples obtained from the borings included natural moisture
content and density and gradation analyses. Results of swell -consolidation testing performed on
relatively undisturbed drive samples of the silt and clay soils, presented on Figures 4 and 5,
indicate low compressibility under light loading and moderate to minor collapse potential
(settlement under constant load) when wetted. Results of gradation analyses performed on a
small diameter drive sample (minus 1'/z -inch fraction) of a more granular layer are shown on
Figure 6. 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
typically slightly moist to moist with depth. When the boreholes were checked 1 day after
drilling, groundwater was measured at about 24 feet in Boring 1.
FOUNDATION BEARING CONDITIONS
The upper natural fine-grained sandy silt and clay with gravel soils possess a relatively low
bearing capacity and a low to moderate collapse potential when wetted under a constant light
load. Spread footings bearing on the natural upper 8 feet of fine-grained soil can be used for
foundation support with the accepted risk of movement and distress. Lower risk options include
extending the footing bearing level down or constructing a basement level bearing on the deeper
(8 feet or more), less collapse -prone natural soils, removal of 3 feet of the natural soil below the
footings and replacement with compacted structural fill or use of a deep foundation, such as
micropiles or drilled piers bearing in dense gravel. Below are design recommendations for
Kumar & Associates, Inc. ® Project No. 20-7-108
-4 -
spread footings. If deep foundations are desired, we should be contacted to provide design
recommendations.
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 bearing
on the natural subsoils at least 8 feet deep or on compacted structural till.
The design and construction criteria presented below should be observed for a spread footing
foundation system.
1) Footings placed on the undisturbed natural subsoils at least 8 feet below existing
ground surface or compacted structural fill should be designed for an allowable
bearing pressure of 1,400 psf. Structural fill should be compacted to a minimum
of 98% of the standard Proctor density. Based on experience, we expect initial
settlement of footings designed and constructed as discussed in this section will
be about 1 inch. Additional movement of around 1 inch could occur if the bearing
soils are wetted. Less movement is expected for footings bearing on a minimum
of 3 feet of compacted structural fill or footings that are bearing on the deeper,
less collapse -prone soil depending on the depth and extent of wetting.
2) The footings should have a minimum width of 20 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 heavily 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
lateral earth pressures as discussed in the "Foundation and Retaining Walls"
section of this report.
Kumar & Associates, Inc. ® Project No. 20-7-108
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5) The topsoil and any loose or disturbed soils should be removed and the footing
bearing level extended down to the firm natural soils. The exposed soils in
footing area should then be moisture adjusted to near optimum and compacted.
6) A representative of the geotechnical engineer should observe all footing
excavations prior to concrete placement to evaluate bearing conditions.
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 at least 50 pcf for backfill consisting
of the on-site fine-grained soils.
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 and
walkway areas 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.
The lateral resistance of foundation or 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 of compacted backfill against the
sides of the footings can be calculated using an equivalent fluid unit weight of 350 pcf. The
coefficient of friction and passive pressure values recommended above assume ultimate soil
Kumar & Associates, Inc. 0 Project No. 20-7-108
6 -
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 compacted to at least 95% of the
maximum standard Proctor density at a moisture content near optimum.
FLOOR SLABS
The natural on-site soils, exclusive of topsoil, can be used to support lightly loaded slab -on -grade
construction with the accepted risk of movement as described above for foundations. The risk of
movement of slabs at shallow depth can be reduced by placing slabs -on -grade on a minimum of
2 feet of compacted structural fillror by using structural floors over crawlspace, which is
commonly done in the area. The structural fill should consist of a granular soil such as CDOT
Class 5 or 6 base course material.
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 than 2%
passing the No. 200 sieve.
All fill materials for support of floor slabs should becompactedto at least 95% of maximum
standard Proctor density at a moisture content near optimum. Required fill, below the
recommended depth of base course, can consist of the on-site soils devoid of vegetation, topsoil
and oversized rock (plus 4 -inch).
UNDERDRAIN SYSTEM
Although free water was encountered well below expected excavation depth, it has been our
experience in the area and where there are clay soils that local perched groundwater can develop
during times of heavy precipitation or seasonal runoff. Frozen ground during spring runoff can
create a perched condition. We _recommend below -grade construction, such as retaining walls
and basement areas, be protected from wetting and hydrostatic pressure buildup by an underdrain
Kumar & Associates, Inc. ® Project No. 20-7-108
7
system. Shallow crawlspace areas should not need an underdrain with proper exterior grading
and surface drainage.
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 1 foot below lowest adjacent finish grade and sloped at a minimum 1% to
a suitable gravity outlet. Free -draining granular material used in the underdrain system should
contain less than 2% passing the No. 200 sieve, less than 50% passing the No. 4 sieve and have a
maximum size of 2 inches. The drain gravel backfill should be at least 1'/z feet deep. A PVC
30 -mil liner should be placed under the drain gravel in a trough shape and attached to the footing
with mastic to prevent the filtration of water in the drain gravel to the underlying bearing soils.
SURFACE DRAINAGE
The following drainage precautions should be observed during construction and maintained at all
times after the residence has been completed:
1) Inundation of the 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% of the maximum standard Proctor density in pavement and slab areas
and to at least 90% 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 should be
covered with filter fabric and capped with about 2 feet of the on-site finer -grained
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
10 feet from foundation walls. Consideration should be given to use of xeriscape
to reduce the potential for wetting of soils below the building caused by irrigation.
Kumar & Associates, Inc. ® Project No. 20-7-108
8
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 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
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 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.
Respectfully Submitted,
Kumar & Associates, Inc.
Shane J. Robat, P.E.
Reviewed by:
Steven L. Pawlak,
SJR/kac
Kumar & Associates, Inc.
Project No. 20.7.108
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20-7-108
Kumar & Associates
LOCATION OF EXPLORATORY BORINGS
Fig. 1
- 0
- 5
- 10
- 15
- 20
25
- 30
BORING 1
EL. 100'
20/12
11/12
WC=6.5
DD=98
- 200=53
34/12
WC=7.4
DD=122
+4=43
- 200=36
9/12
7/12
WC=23.5
- 200=58
31/6,50/5
BORING 2
EL. 99'
6/12
11/12
WC=12.8
DD=103
21/12
WC=18.8
DD=100
11/12
WC=25.2
DD=99
-200=84
6/6,41/6
0
5
10
15
20
25
30
1-
LJ
w
L-
0-
1.1.1
-
aw
0
20-7-108
Kumar & Associates
LOGS OF EXPLORATORY BORINGS
Fig. 2
LEGEND
ti
TOPSOIL; SANDY CLAY AND SILT, ORGANICS, FIRM, MOIST, DARK BROWN.
ZIP
CLAY AND SILTY (CL -ML); SANDY TO VERY SANDY, SCATTERED GRAVEL AND COBBLES,
OCCASIONAL GRAVEL ZONES (BASALT FRAGMENTS), MEDIUM STIFF TO STIFF, SLIGHTLY
MOIST TO VERY MOIST WITH DEPTH, BROWN, GYPSIFEROUS.
SAND AND GRAVEL (SM -GM); SILTY WITH COBBLES AND POSSIBLE BOULDERS, DENSE,
VERY MOIST TO WET, MIXED BROWN, ROUNDED ROCK.
DRIVE SAMPLE, 2 -INCH I.D. CALIFORNIA LINER SAMPLE.
DRIVE SAMPLE, 1 3/8 -INCH I.D. SPLIT SPOON STANDARD PENETRATION TEST.
20/12 DRIVE SAMPLE BLOW COUNT. INDICATES THAT 20 BLOWS OF A 140 -POUND HAMMER
FALLING 30 INCHES WERE REQUIRED TO DRIVE THE SAMPLER 12 INCHES.
DEPTH TO WATER LEVEL AND NUMBER OF DAYS AFTER DRILLING MEASUREMENT WAS MADE.
DEPTH AT WHICH BORING CAVED WHEN CHECKED ON JANUARY 15, 2020.
t PRACTICAL AUGER REFUSAL.
NOTES
1. THE EXPLORATORY BORINGS WERE DRILLED ON JANUARY 14, 2020 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 MEASURED BY HAND LEVEL AND REFER
TO BORING 1 AS 100', ASSUMED.
4. THE EXPLORATORY BORING LOCATIONS AND ELEVATIONS 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 LEVELS SHOWN ON THE LOGS WERE MEASURED AT THE TIME AND UNDER
CONDITIONS INDICATED. FLUCTUATIONS IN THE WATER LEVEL MAY OCCUR WITH TIME.
7. LABORATORY TEST RESULTS:
WC = WATER CONTENT (%) (ASTM 02216);
DD = DRY DENSITY (pcf) (ASTM 02216);
+4 = PERCENTAGE RETAINED ON NO. 4 SIEVE (ASTM D6913);
-200= PERCENTAGE PASSING NO. 200 SIEVE (ASTM D1140).
20-7-108
Kumar & Associates
LEGEND AND NOTES
Fig. 3
2
0
J —2
W
u,
—4
z
O
1-
2 —6
-J
O
to
z
O
U —8
—10
—12
10 APPLIED PRESSURE —
100
20-7-108
Kumar & Associates
SWELL—CONSOLIDATION TEST RESULTS
Fig. 4
SAMPLE OF: Sandy Silt and Clay with
Gravel
FROM: Boring 1 0 5'
WC = 6.5 %, DD = 98 pcf
—200 = 53 %
---;
ADDITIONAL COMPRESSION
UNDER CONSTANT PRESSURE
DUE TO WETTING
These test restate appy only to the
emn a 'n4& Th. hal y'g wog
NMI not ns reprodua3. enctpt in
0,40, without 150 .4lInn Cfs.ced nt
Kumar end In.cc141o0. Inc. Swell
,Consolldotion testing perrermad in
.ocoordnoce With ASIM 0-4546
10 APPLIED PRESSURE —
100
20-7-108
Kumar & Associates
SWELL—CONSOLIDATION TEST RESULTS
Fig. 4
CONSOLIDATION - SWELL
—2
J
0
CONSOLIDATION
—2
SAMPLE OF: Sandy Silt and Clay
FROM: Boring 2 0 5'
WC = 12.8 %, DD = 103 pcf
ti
ADDITIONAL COMPRESSION
UNDER CONSTANT PRESSURE
DUE TO WETTING
1 0 APPLIED PRESSURE — KSF 10 100
SAMPLE OF: Sandy Silt and Clay
FROM: Boring 2 0 10'
WC = 18.8 %, DD = 100 pcf
r
NO MOVEMENT UPON
WETTING
Th... UM omits appy Galt to en.
.em$r.. tared In. tort »part
a1 .ilh0. mt tn. pmrd WOO or
kumer awl Awndat.l >•e_CvntorldalcIS.GII
ocaordanu.Pp�S A
1.0 APPLIED PRESSURE — KSF 10 100
20-7-108
Kumar & Associates
SWELL -CONSOLIDATION TEST RESULTS
Fig. 5
HYDROMETER ANALYSIS
SIEVE ANALYSIS
1185 7 HRS
TIME READINGS
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_ IN_ 06 #!a 00.--/.1,—./.1
ARIES
CLEAR SQUARE DPENNfS
3/0' 3/4'.. 1 . 1 2- r -�+ 6p-�
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DIAMETER OF PARTICLES IN MILLIMETERS
.31< 4.75 9A 19 39.1 76.2 1272.032300
SAND GRAVEL
COBBLES
CLAY TO SILT
FINE MEDIUM COARSE FINE I COARSE
GRAVEL 43 X SAND 21 X SILT AND CLAY 36 X
LIQUID LIMIT PLASTICITY INDEX
SAMPLE OF: Very Silty Very Clayey Sandy Gravel FROM: Boring 1 0 10'
These lest results apply only to the
samples which were holed. The
!soling raporl shall not be •produced,
ekoepl 1n full, wl houl the wrHSen
approval of Kumar & Aslosloles, 1116.
Slave analysis Ieilinj Is performed In
accol'donce w111, ASSN 06913. ASTM D7928,
ASTM C136 and/or ASTM 01140.
20-7-108
Kumar & Associates
GRADATION TEST RESULTS
Fig. 6
K+A
Kumar & Assoc .I.•
Geotechnical and Materials Engineers
and Environmental Scien s
TABLE 1
SUMMARY OF LABORATORY TEST RESULTS
Pro act No. 20.7.108
SAMPLE LOCATION
NATURAL
MOISTURE
CONTENT
(%)
NATURAL
DRY
DENSITY
(pcf)
GRADATION
PERCENT
P IISIEG NO.
200(ft)
ATTERBERG LIMITS
UNCONFINED
COMPRESSIVE
STRENGTH
(pif
SOIL TYPE
BORING DEPTH
—
GRAVEL
C/o)
SAND
)
1
LIQUID LIMB
(%)
PLASTIC
INDEX
(94)
1
5
6.5
98
53
Sandy Silt and Clay with
Gravel
10
7.4
122
43
21
36
Very Silty Very Clayey
Sandy Gravel
20
23.5
58
Sandy Silt and Clay with
Gravel
2
5
12.8
103
' Sandy Silt and Clay
10
18.8
100
; Sandy Silt and Clay
15
25.2
99
84
Sandy Silt and Clay