HomeMy WebLinkAboutSoils Report 08.31.2016H-P�KUMAR
Geotechnical Engineering I Engineering Geology
Materials Testing i Environmental
5020 County Road 154
Glenwood Springs, CO 81601
Phone: (970) 945-7988
Fax: (970) 945-8454
Email: hpkgienwood@kumarusa.com
Office Locations: Parker, Glenwood Springs, and Silverthome, Colorado
SUBSOIL STUDY
FOR FOUNDATION DESIGN
PROPOSED RESIDENCE
LOT 272, IRONBRIDGE
BLUE HERON VISTA
GARFIELD COUNTY, COLORADO
PROJECT NO. 16-7 311
AUGUST 31, 2016
PREPARED FOR:
KEVIN EMERSON
C/O RM CONSTRUCTION
ATTN: BLAKE PILAND
5030 COUNTY ROAD 154
GLENWOOD SPRINGS, CO 81601
blake@buildwithrm.com
TABLE OF CONTENTS
PURPOSE AND SCOPE OF STUDY - 1 -
BACKGROUND INFORMATION - 1 -
PROPOSED CONSTRUCTION - 2
SITE CONDITIONS - 2 -
SUBSIDENCE POTENTIAL - 2 -
FIELD EXPLORATION - 3 -
SUBSURFACE CONDITIONS - 4 -
FOUNDATION BEARING CONDITIONS - 4 -
DESIGN RECOMMENDATIONS - 5 -
FOUNDATIONS - 5 -
FOUNDATION AND RETAINING WALLS - 6 -
NONSTRUCTURAL FLOOR SLABS - 7 -
UNDERDRAIN SYSTEM - 8 -
SURFACE DRAINAGE - 8 -
LIMITATIONS - 9 -
FIGURE 1 - LOCATION OF EXPLORATORY BORING
FIGURE 2 - LOG OF EXPLORATORY BORING
FIGURE 3 - LEGEND AND NOTES
FIGURES 4 and 5 - SWELL -CONSOLIDATION TEST RESULTS
TABLE 1- SUMMARY OF LABORATORY TEST RESULTS
H -F KUMAR
PURPOSE AND SCOPE OF STUDY
This report presents the results of a subsoil study for a proposed residence to be located
on Lot 272, Ironbridge, Blue Heron Vista, 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 accordance with our agreement for
geotechnical engineering services to Kevin Emerson c/o RM Construction dated August
8, 2016. Hepworth-Pawlak Geotechnical (now H-P/Kumar) previously performed a
preliminary geotechnical study for the Ironbridge Villas and presented our findings in a
report dated September 14, 2005, Job No. 105 115-6.
A field exploration program consisting of an exploratory boring 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.
BACKGROUND INFORMATION
The proposed residence is located in the existing Ironbridge subdivision development.
Hepworth-Pawlak Geotechnical (now H-P/Kumar) previously conducted subsurface
exploration and geotechnical evaluation for development of Villas North and Villas South
parcels, Job No. 105 115-6, report dated September 14, 2005, and performed observation
and testing services during the infrastructure construction, Job No. 106 0367 between
April 2006 and April 2007. The information provided in these previous reports has been
considered in the current study of Lot 272.
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PROPOSED CONSTRUCTION
The proposed residence will be a one story, wood frame structure with attached garage
and located as shown on Figure I. Ground floors are proposed to consist of a structural
slab -on -grade with no basement or crawlspace. 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 lot was vacant at the time of the field exploration. The terrain was relatively flat with
about one foot of elevation difference down to the east. Fill had been placed to elevate
the lot and surrounding area by the previous subdivision grading. The lot was accessed
off a driveway coming from Blue Heron Vista to the east. Vegetation consisted of grass,
weeds and sagebrush.
SUBSIDENCE POTENTIAL
Bedrock of the Pennsylvanian age Eagle Valley Evaporite underlies the Ironbridge
development. 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. A sinkhole opened
in the cart storage parking lot located east of the Pro Shop and west of the Villas North
parcel in January 2005. Other irregular bedrock conditions have been identified in the
affordable housing site located to the northwest of the Villas North parcel. Irregular
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surface features that could indicate an unusual risk of future ground subsidence were not
observed in the Villas North parcel, but localized variable depths of debris fan soils and
bedrock quality encountered by the previous September 14, 2005 geotechnical study in
the Villas North development area could be the result of past subsidence. The subsurface
exploration performed in the area of the proposed residences on Lots 272/273 did not
encounter voids but the alluvial fan depth encountered was considerably greater than
encountered on nearby lots which could indicate past ground subsidence. In our opinion,
the risk of future ground subsidence on Lot 272 in the Villas North parcel throughout the
service life of the proposed residence is low and similar to other areas of the Roaring Fork
River valley where there have not been indications of ground subsidence, but 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 current project was conducted on August 10, 2016. One
exploratory boring was drilled at the location shown 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 -45B drill rig. The boring was logged by a
representative of H-13/Kumar.
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 and hardness of the bedrock. 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.
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SUBSURFACE CONDITIONS
A graphic log of the subsurface conditions encountered at the site is shown on Figure 2.
The subsoils consist of about 8 feet of relatively dense, mixed sandy clayey silt and gravel
fill overlying about 71/2 feet of stiff, sandy silt with gravel underlain by about 211/2 feet of
medium dense/very stiff, silty to very silty sand with gravel. Below the silty sand at
about 37 feet deep, was about 5 feet of medium dense, silty sand and gravel underlain by
claystone and gypsum bedrock to the maximum drilled depth of 61 feet. The bedrock is
Eagle Valley Evaporite and was typically very weathered and became less weathered and
very hard with depth.
Laboratory testing performed on samples obtained from the boring included natural
moisture content and density and finer than sand size gradation analyses. Results of
swell -consolidation testing performed on relatively undisturbed drive samples, presented
on Figures 4 and 5, indicate low to moderate compressibility under loading and low to
minor collapse potential (settlement under constant load) when wetted. The laboratory
testing is summarized in Table 1.
Free water was encountered in the boring at the time of drilling and when checked 1 day
later at a depth of about 43 feet. The upper soils were slightly moist to moist with depth
becoming very moist to wet near and below groundwater level.
FOUNDATION BEARING CONDITIONS
The upper 8 feet of soils consist of fill placed mainly in 2006 as part of the subdivision
development. The field penetration tests (blow counts) and laboratory tests performed for
the current study, and review of the field density (compaction) tests performed during the
fill construction indicate the structural fill was placed and compacted to the project
specified 95% of standard Proctor density. Debris fan soils which tend to collapse (settle
under constant load) when wetted were encountered below the fill. The amount of
settlement will depend on the thickness of the compressible soils due to potential collapse
H-Fk. KUMAR
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when wetted, and potential compression of the underlying soils after wetting. Relatively
deep structural fill will also have some potential for long term settlement but should be
considerably less than the alluvial fan deposit. Sources of wetting include irrigation,
surface water runoff and utility line leaks. A heavily reinforced structural slab or post -
tensioned slab foundation designed for significant differential settlements is
recommended for the building support.
DESIGN RECOMMENDATIONS
FOUNDATIONS
Considering the subsurface conditions encountered in the exploratory boring and the
nature of the proposed construction, we recommend the building be founded with a
heavily reinforced structural slab foundation bearing on about 8 feet of compacted
structural fill. A post -tensioned slab foundation could also be used.
The design and construction criteria presented below should be observed for a spread
footing foundation system.
1) A heavily reinforced structural slab placed on about 8 feet of structural fill
should be designed for an allowable bearing pressure of 1,500 psf. A post -
tensioned slab if used should be designed for a wetted distance of 10 feet
2)
but at least half of the slab width, whichever is more.
Based on
experience, we expect initial settlement of the slab foundation designed
and constructed as discussed in this section will be about 1 inch or less.
Additional settlement could occur if the bearing soils were to become
wetted. The magnitude of the additional settlement would depend on the
depth and extent of wetting but may be on the order of 1 to 1'/2 inches.
The thickened sections of the slab for support of concentrated loads should
have a minimum width of 20 inches.
3) The perimeter turn -down section of the slab should be provided with
adequate soil cover above the bearing elevation for frost protection.
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Placement of foundations at least 36 inches below exterior grade is
typically used in this area. If a frost protected foundation is used, the
perimeter turn -down section should have at least 18 inches of soil cover.
4) The foundation should be constructed in a "box -like" configuration rather
than with irregular extensions which can settle differentially to the main
building area. The foundation walls, where provided, should be heavily
reinforced top and bottom to span local anomalies such as by assuming an
unsupported length of at least 14 feet. Foundation walls acting as retaining
structures (if any) should also be designed to resist Iateral earth pressures
as discussed in the "Foundation and Retaining Walls" section of this
report.
5) The organic root zone and any loose or disturbed soils should be removed.
Additional structural fill placed below the slab bearing level should be
compacted to at least 98% of the maximum standard Proctor density at a
moisture content near optimum.
6) A representative of the geotechnical engineer should evaluate the
compaction of fill materials and 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 soils. Cantilevered retaining structures which are
separate from the building 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 at least 40 pcf for backfill consisting of
the on-site soils.
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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 300 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 compacted to at least 95% of the maximum standard Proctor density at a
moisture content near optimum.
NONSTRUCTURAL FLOOR SLABS
Compacted structural fill can be used to support lightly loaded slab -on -grade construction
separate from the building foundation. The fill soils can be compressible when wetted
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and result in some post -construction settlement. To reduce the effects of some
differential movement, slabs -on -grade should be separated from the building to 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 well -graded sand and gravel, such as road base,
should be placed beneath slabs for support. This material should consist of minus 2 -inch
aggregate with at least 50% retained an the No. 4 sieve and Less than 12% passing the No.
200 sieve.
All fill materials for support of floor slabs should be compacted to at Least 95% of
maximum standard Proctor density at a moisture content near optimum. Required fill can
consist of the on-site soils devoid of vegetation, topsoil and oversized rock.
UNDERDRAIN SYSTEM
It is our understanding that the finished floor elevation at the lowest level of the proposed
residence will be at or above the surrounding grade. Therefore, a foundation drain system
Although free water was encountered during our exploration well below
is not required.
probable foundation depths, it has been our experience in the area 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, be protected from wetting and hydrostatic pressure
buildup by an underdrain system.
If finished floor elevation of the proposed residence has a floor level below the
surrounding grade, we should be contacted to provide recommendations for an underdrain
system. All earth retaining structures should be properly drained.
SURFACE DRAINAGE
Precautions to prevent wetting of the bearing soils, such as proper backfill construction,
positive backlit] slopes, restricting landscape irrigation and use of roof gutters need to be
H -PL KUMAR
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taken to limit settlement and building distress. 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 6 inches in the first 5 feet in unpaved
areas and a minimum slope of 2% inches in the first 10 feet in paved areas.
Graded swales should have a minimum slope of3%.
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.
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 boring drilled at the location 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
H -I* KUMAR
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consulted. Our findings include interpolation and extrapolation of the subsurface
conditions identified at the exploratory boring 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 Feld 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,
H -P - KU MAR
Steven L. Pawlak, P.E.
SLP/ksw
cc: RM Construction — Eric i r (ericObuiltwithrrn.com)
H -Fit KUMAR
f
LOT 273 (VACANT)
1 1 1 I
BORING 1
int
1
1
1
1
10 0 10 20
APPROXIMATE SCALE—FEET
LOT 272
PROPOSED RESIDENCE
LOT 271 (BUILT)
1
11
1
1
1
1
5
ta
ad
CD
16--7--311
H-PiKUMAR
LOCATION OF EXPLORATORY BORING
Fig. 1
a
3
w
W
z
0
P
— 5960
— 5950
— 5940
— 5930
--- 5920
— 5910
— 5900
•- 5890
BORING 1
EL. 5958'
70/12
WC=8.3
DD=129
— 200=67
86/12
13/12
WC=21.7
D0=92
59/3
WC=8.6
00=119
— 200=49
18/12
WC=8.0
00=119
49/12
13/12
WC=8.9
—200=45
17/12
2/12
50/2
5960 ---
5950
5950 —
5940-
940---
5930-
5930-
5920-
5920-
5910
5910 —
5900-
900-
5890-
5890-
0
0
?i
16-7-311
H—P�KUMAR
C.o 2ncsl Esc l EMINN d.*Crt
l uueul/ T.eerq l innenm.ny
LOGS OF EXPLORATORY BORINGS
Fig. 2
LEGEND
®FILL; MIXED SANDY CLAYEY SILT AND GRAVEL, MEDIUM DENSE. SUGHTLY MOIST, BROWN.
7
L
7
SILT (ML); SUGHTLY CLAYEY, SANDY, SCATTERED GRAVEL. STIFF. MOIST. REDDISH BROWN.
SAND AND SILT (SM—ML); SCATTERED GRAVEL MEDIUM DENSE/VERY STIFF, M015T, REDDISH
BROWN.
SAND AND GRAVEL (5M—GM); SILTY, SOME SANDY SILT LAYERS. MEDIUM DENSE, BROWN.
SUBANGULAR TO ROUNDED ROCK.
WEATHERED CLAYSTONE AND GYPSUM; SOFT TO HARD WITH DEPTH, VERY MOIST TO WET,
GRAY AND WHITE. EAGLE VALLEY EVAPORITE.
RELATIVELY UNDISTURBED DRIVE SAMPLE; 2—INCH I.D. CALIFORNIA LINER SAMPLE.
DRIVE SAMPLE; STANDARD PENETRATION TEST (SPT). 1 3/8 INCH 1.0. SPLIT SPOON
SAMPLE, ASTM D-1586.
70/12 DRIVE SAMPLE BLOW COUNT. INDICATES THAT 70 BLOWS OF A 140—POUND HAMMER
FALLING 30 INCHES WERE REQUIRED TO DRIVE THE CALIFORNIA OR SPT SAMPLER 12 INCHES.
1 DEPTH TO WATER LEVEL AND NUMBER OF DAYS AFTER DRILLING MEASUREMENT WAS MADE.
DEPTH AT WHICH BORING CAVED.
NOTES
1. THE EXPLORATORY BORING WAS DRILLED ON AUGUST 10, 2016 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 MEASURED BY INTERPOLATION BETWEEN
CONTOURS ON THE 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 BOUNDARIES BETWEEN MATERIAL TYPES AND THE TRANSITIONS MAY BE GRADUAL
6. GROUNDWATER LEVEL SHOWN ON THE LOG WAS MEASURED AT THE TIME AND UNDER
CONDITIONS INDICATED. FLUCTUATIONS IN THE WATER LEVEL MAY OCCUR WITH TIME.
7. LABORATORY TEST RESULTS:
WC = WATER CONTENT (X) (ASTM 0 2216);
OD = DRY DENSITY (pcf) (ASTM 0 2216);
—200= PERCENTAGE PASSING NO. 200 SIEVE (ASTM 0 1140).
16-7-311
H-P-KUMAR
CoarwriYe. Mos tenfreutCmannwrava
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LEGEND AND NOTES
Fig. 3
1
0
—2
3
z
0
z
0
1 --5
— 6
— 7
16-7-311
H-P-KUMAR SWELL -CONSOLIDATION TEST RESULT
r ns nwF�.n+.p=C+rirwo• 1
IAv.rLnf. T.anm 1 rn,b...w.Mal
Fig. 4
SAMPLE OF: Sandy Clayey 5111
FROM: Boring 1 0 10'
WC = 21.7 X. DD = 92 pct
11111
I
ADDITIONAL COMPRESSION
UNDER CONSTANT PRESSURE
DUE TO WETTING
111
II
111111
iiik
II
i_
1
_
11
1111
lbwss isst.r . ameoc e r u
=WI b. n ndrog. sill In
.0iIia4 w .. w.r r
f 1v1
za aw sYYw. .s
Cnw.ai.M�..M
arrd.r .M 0-474L
1 10 APPUED PRESSURE
— KSF 10
10
16-7-311
H-P-KUMAR SWELL -CONSOLIDATION TEST RESULT
r ns nwF�.n+.p=C+rirwo• 1
IAv.rLnf. T.anm 1 rn,b...w.Mal
Fig. 4
2
1
1
0
1
ur
—2
z
0
7 0 —3
0
Ul
z
0
u _4
100
16-7-311
H-P�KUMAR
C.:17, r.Y tlq.V..m3 EegF,•werq 0.
IA•+•�W. T..n i f n.�r+•.r•�
SWELL -CONSOLIDATION TEST RESULT
Fig. 5
SAMPLE OF: Very Silty Sand with Gravel
FROM: Boring 1 0 20'
WC = B.0 X, DD = 119 pci
11
ADDITIONAL COMPRESSION
UNDER CONSTANT
DUE TO WETTING
PRESSURE
111 I
IIII 111
1
1
III
UN WO Www —.�y w rr
in d h
U ifM. moot
t2. Wiwi W4 wino pmol r
I — !nmaleK�Inc /+M
w
M
namonser iA{N 6�,
100
16-7-311
H-P�KUMAR
C.:17, r.Y tlq.V..m3 EegF,•werq 0.
IA•+•�W. T..n i f n.�r+•.r•�
SWELL -CONSOLIDATION TEST RESULT
Fig. 5
Project No. 16-7-311
SUMMARY OF LABORATORY TEST RESULTS
N
N
O
J
SOIL OR
BEDROCK TYPE
Sandy Clayey Silt with
Gravel (Fill)
Sandy Clayey Silt
Very Silty Sand with 11
Gravel
Very Silty Sand with
Gravel
Very Silty Sand with
Gravel
UNCONFINED
COMPRESSIVE
STRENGTH
(PSF}
ATTERBERG LIMITS
PLASTIC
INDEX
f
d2
3
PERCENT
PASSING
NO.200
SIEVE
'0
en
V,
_ _ GRADATION
0
Za
CI
GRAVEL
(%)
NATURAL
DRY
DENSITY
(Pci)
N
0,
0%
—
0,
—
NATURAL.
MOISTURE
CONTENT
(x)
rel
00
n
N
00
0
00
0%
00
11 SAMPLE LOCATION
E4
W
0
\
N
O
^'
in
^'
O
N
O
r*1
0
z
E
0
m
--
H-P_KUMAR
Geolechnice) Engineering i Engineering Geology
Materials Testing 1 Environmental
5020 County Road 154
Glenwood Springs, CO 81601
Phone: (970) 945-7988
Fax: (970) 945-8454
Email: hpkglenwood@kumarusa.com
September 8, 2016
Kevin Emerson
c/o RM Construction
Attn: Blake Piland
5030 County Road 154
Glenwood Springs, Colorado 81601
Blake a,buildwithrm.com
Office Locations: Parker, Glenwood Springs, and Silverthome, Colorado
Project No. 16-7-311
Subject: Addendum of Subgrade Modulus to Subsoil Study Reports, Proposed Residences,
Lots 272 and 273, Ironbridge, Blue Heron Vista, Garfield County, Colorado
Gentlemen:
As requested, we are providing the recommended subgrade modulus for design of structural slab
foundations at the subject site. We previously conducted subsoil studies for design of
foundations at each of Lots 272 and 273 and presented our findings in reports dated August 31,
2016, Project No. 16-7-311.
The soils mainly consist of slightly clayey sandy silt with gravel.
can be used for the structural slab design. Other recommendations presented in our previous
reports which are applicable should also be observed.
A subgrade modulus of 100 tcf
If you have any questions or need further assistance, please call our office.
Sincerely,
H-P� KUMAR
Steven L. Pawlak, P.E.
SLP/ksw