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HEPWORTH-PAWLAK GEOTECHNICAL
SUBSOIL STUDY
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FOR FOUNDATION DESIGN
PROPOSED ELECTRIC SYSTEM OPERATIONS
CENTER AND COMMUNITY BROADBAND
NETWORK OPERATIONS CENTER
1660 DEVEREUX ROAD
GLENWOOD SPRINGS, COLORADO
JOB NO. 113 422A
JANUARY 10, 2014
PREPARED FOR:
SGM, INC.
ATTN: DAN RICHARDSON
118 WEST 6TH STREET, SUITE 200
GLENWOOD SPRINGS, COLORADO 81601
dan r@'sgm-inc.com
TABLE OF CONTENTS
PURPOSE AND SCOPE OF STUDY .......................................................................... -1 -
PROPOSED CONSTRUCTION .................................................................................. c 1-
SITE CONDITIONS .................................................................................................... -2 -
GEOLOGIC CONDITIONS ........................................................................................ ~ 2-
FIELD EXPLORATION .............................................................................................. -3 -
SUBSURFACE CONDITIONS .................................................................................... -3-
FOUNDATION BEARING CONDITIONS., ............................................................... -4-
DESIGN RECOMMENDATIONS ............................................................................... -5 -
DRILLED PIERS ..................................................................................................... -5 -
FOUNDATION ALTERNATIVE ............................................................................ -6-
FOUNDATION AND RETAINING WALLS .......................................................... ~ 7-
FLOOR SLABS ....................................................................................................... -8 -
UNDERDRAIN SYSTEM ....................................................................................... ~ 9-
SITE GRADING .................................................................................................... -10-
SURFACE DRAINAGE ........................................................................................ ~ 12-
LIMITATIONS .......................................................................................................... -12-
REFERENCE ............................................................................................................. -14-
FIGURE 1 -LOCATION OF EXPLORATORY BORINGS
FIGURES 2 AND 3-LOGS OF EXPLORATORY BORINGS
FIGURE 4 -LEGEND AND NOTES
FIGURES 5 THROUGH 9-SWELL-CONSOLIDATION TEST RESULTS
TABLE 1-SUMMARY OF LABORATORY TEST RESULTS
PURPOSE AND SCOPE OF STUDY
This report presents the results of a subsoil study for the proposed electric system and
community broadband network operations centers to be located at 1660 Devereux Road,
Glenwood Springs, Colorado. The project site is shown on Figure I. The purpose of the
study was to develop recommendations for the foundation design. The study was
conducted in general accordance with our proposal for geotechnical engineering services
to SGM, Inc, dated October 4, 2013. The scope of services was increased to include a
separate building for the Broadbm1d Network Operations Center.
A field exploration prograJTI 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 subsoil conditions encountered.
PROPOSED CONSTRUCTION
The proposed development includes 2 buildings, outside storage, parking and drives
located as shown on Figure I. Ground floors will be slab-on-grade. Grading for the
buildings and facilities will be considerable to develop flat building sites, parking and
driveways with a tiered retaining wall along the uphill side of the property. The buildings
will be masonry block and steel construction. We assume relatively light to moderate
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 repoti.
Job No. 113 422A ~tech
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SITE CONDITIONS
The property was vacant of structures at the time of our field exploration. A gravel
driveway crosses through the property from Devereux Road to access an electrical
substation at the west end of the proposed development area. The ground surface slope is
moderate down to the north with about 20 feet of elevation difference across the property
and 5 to 8 feet of elevation difference across each building area. The Denver and Rio
Grande Railroad property follows the south side of the property. The Colorado River is
located just north of Devereux Road and on the order of 15 feet lower in elevation.
Devereux Road appears to have been constructed mainly by cutting into the slope on the
order of5 to 10 feet at the bottom oftheproperty. Vegetation consists of grass, weeds and
fairly thick sage brush.
GEOLOGIC CONDITIONS
The project site is located in the lower part of a large alluvial fan deposit consisting of
poorly stratified silt, sand and gravel derived from weathering and erosion of Maroon
Formation rock that forms the south valley side of the Colorado River valley near the
project site. The alluvial fan deposits in this area are known to be compressible and
collapse when wetted which can result in distress to buildings supported by these soils.
The hydro-compression potential is considered moderate in this area of the alluvial fan
(Lincoln-DeVore, 1978). The underlying soils consist of relatively dense, river gravel
deposits of the Colorado River that are known to typically support moderate to high
foundation loadings with low settlement risk. Alluvial fan surface can be potentially
impacted by debris flow but with the relatively wide railroad track area located
immediately uphill of the project site, this risk is low and mitigation to further reduce the
risk does not appear needed. If further evaluation of the debris flow 1isk is desired, we
should be contacted. Options to mitigate the hydro-compression potential of the alluvial
fan soils are presented below in the Foundation Bearing Conditions and Design
Recommendations sections of the report.
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FIELD EXPLORATION
The field exploration for the project was conducted on November 26 and December 2 and
3, 2013. Eight 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 auger powered by a track-mounted CME-45 and a truck-mounted CME-
45B drill rigs. The track rig was needed for access off of the existing driveway trail due
to the sloping terrain and vegetation cover. The borings were logged by a representative
of Hepworth-Pawlak Geotechnical, 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,
Figures 2 and 3. The samples were returned to our laborat01y for review by the project
engineer and testing.
SUBSURFACE CONDITIONS
Graphic logs of the subsurface conditions encountered at the site are shown on Figures 2
and 3. The subsoils consist of about Y, foot of topsoil overlying loose to medium dense,
poorly stratified sandy silt and silty sand with gravel and scattered cobble size rock
fragments (alluvial fan deposits). Dense, slightly silty sandy gravel, cobbles and boulders
(river gravel deposit) was encountered below the silt and sand soils at depths of 17 to 22
feet at the borings. Drilling in the dense river gravel deposit with auger equipment was
difficult due to the cobbles and boulders and drilling refusal was encountered in the
deposit.
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Laboratory testing performed on samples obtained from the borings included natural
moisture content and density, and finer than sand size gradation analyses. Results of
swell-consolidation testing performed on relatively undisturbed drive samples of the silt
and sand soils, presented on Figures 5 through 9, indicate low compressibility under
relatively light loading and natural low moisture conditions. A low to high collapse
potential (settlement under constant load) and moderate to high compressibility were
typically observed when the samples were wetted and additionally loaded. The fine
fraction of the soils is typically none plastic. The laboratory testing is summarized in
Table I.
Ground water was encountered in Borings 1 and 3, located in the lowermost, north part of
the property at depths of about 20 to 25 feet. Free water was not encountered in the
remaining borings and the subsoils were relatively dry to slightly moist.
FOUNDATION BEARING CONDITIONS
The subsoils encountered to depths of about 14 to 22 feet below the proposed building
grades consist of low density and compressible silt and sand soils. These soils are hydro-
compressive and tend to settle under load when wetted. There are several sources of
water that can cause subsurface wetting such as landscape irrigation, site water runoff,
vehicle or equipment washing and utility line leaks. A relatively low risk foundation
system with regard to potential settlement caused by wetting of the silt and sand soils is
straight-shaft drilled piers or piles that extend down into the dense river gravel deposits.
In addition to their ability to reduce settlements, the piers or piles have the advantage of
providing relatively high load capacity with a relatively small settlement potential.
An alternative foundation, with a risk of settlement, is to support the buildings with
spread footings placed on compacted structural fill of sufficient depth to reduce the
settlement potential to an acceptable level. The settlement potential of the natural soils
extending about I 0 to 15 feet below shallow footing depth of the buildings is estimated to
be between 2 to 4 inches for an average soil collapse of about 2%. By removing roughly
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half of the compressible soils below the spread footing depth, the settlement potential of
the natural soils can be reduced to about I to 1 Y, inches due to post construction wetting.
The structural fill will be placed below the entire building and will also reduce potential
settlement and distress to floor slabs. Shallow spread footings placed on the natural soils
should be suitable for support of non-settlement sensitive structures such as retaining
walls provided the owner accepts the settlement risk and need for potentially higher
maintenance and earlier replacement or repair. Provided below are recommendations for
the various foundation alternatives. When the foundation for the specific building or
facility has been selected, we should review the design for compliance with the design
recommendations. A 2009 IBC Seismic Site Class C can be used for design of the
building for foundations placed on compacted structural fill or dense river gravels.
DESIGN RECOMMENDATIONS
DRILLED PIERS
Considering the subsoil conditions encountered in the exploratory borings and the nature
of the proposed construction, we recommend straight shaft piers drilled into the
underlying river gravel deposit for building support. The design and construction criteria
presented below should be observed for a straight-shaft drilled pier foundation system. If
a pile system is proposed for the foundation support, we should be contacted for design
recommendations.
1) The piers should be designed for an allowable end bearing pressure of
12,000 psf and a skin friction of 1,000 psf for that portion of the pier
embedded in river gravel. Pier penetration through the upper silt and sand
deposit should be neglected in the skin. friction calculations.
2) All piers should have a minimum total embedment length of 12 feet and a
minimum penetration into the gravel of 1 foot.
3) The pier holes should be properly cleaned prior to placement of concrete.
Job No. 113 422A
The natural silt and sand soils are generally stiff which indicates casing of
the holes should not be required. Some caving and difficult drilling may
be experienced in the soils due to cobbles and possible boulders in the
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bearing stratum. Placing concrete in the pier hole immediately after
drilling is recommended.
4) The pier drilling contractor should mobilize equipment of sufficient size to
achieve the design pier sizes and depths.
5) Free water was typically not encountered in the borings made at the site
(other than Borings I and 3) and it appears that dewatering should not be
needed during the low flow time of the Colorado River. The groundwater
level is expected to rise with rise ofthe river.
6) A representative ofthe geotechnical engineer should observe pier drilling
operations on a full-time basis.
FOUNDATION ALTERNATIVE
Based on the subsurface conditions identified in the exploratory borings, the buildings
can be supported by lightly loaded spread footings placed on a minimum 6 foot depth of
compacted structural fill with some risk oflong term foundation settlement and building
distress. The design and construction criteria presented below should be observed for a
spread footing foundation system.
I) Footings should be placed on a minimum 6 foot depth of compacted
structural fill and be designed for an allowable bearing pressure of 2,000
psf. Based on experience, we expect settlement of footings, in the short
term, designed and constructed as discussed in this section will be about I
inch or less (roughly I to I Y,% ofthe structural fill depth). Additional
settlement of about I to I Y, inches could occur over a long time period and
mainly if there is relatively deep wetting of the natural alluvial fan soils.
Heavily reinforced continuous wall foundations rather than isolated pads
should be used to limit the effects of differential settlement.
2) Prior to placing structural fill for the foundation, the area should be
stripped of the vegetation and topsoil. Structural fill should be placed in
uniform lifts not to exceed 8 inches and compacted to at least 100% ofthe
maximum standard Proctor density within 2% of optimum moisture
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content. Fill should extend laterally beyond the edges-of the footing a
distance at least equal to the depth of fill below the footing_ The structural
fill should have sufficient fines content (roughly 30%) to restrict
subsurface water flow such as the on-site silts.
3) The footings should have a minimum width of 18 inches for continuous
walls and 2 feet for isolated pads.
4) 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 3 6 inches below exterior grade is
typically used in this area.
5) Continuous foundation walls should be reinforced top and bottom to span
an unsupported length of at least 14 feet.
6) A representative of the geotechnical engineer should evaluate fill
placement for compaction and observe all footing excavations prior to
concrete placement to evaluate bearing conditions.
FOUNDATION AND RETAlNlNG 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 50 pcffor
backfill consisting of the on-site soils. Cantilevered retaining structures which are
separate from the buildings 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 40 pcffor backfill consisting of the on-
site soils. The foundations of walls which are not settlement sensitive and the risk of
potential settlement and distress is acceptable to the owner can be supported on the
natural soils with an allowable bearing pressure of 1,500 psf.
All foundation and retaining structures should be designed for appropriate hydrostatic and
surcharge pressures such-as adjacent footings, traffic, construction materials and
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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 near optimum moisture content. 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 of0.40. Passive pressure of compacted
backfill against the sides of the footings can be calculated using an equivalent fluid unit
weight of350 pcf. The coefficient of friction and passivepressure 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.
FLOOR SLABS
The alluvial soils encountered in the borings possess compressibility potential and slab
settlement could occur if the bearing soils were to become wet. Slab-on-grade
construction may be used provided precautions are taken to limit potential settlement and
the risk of distress to the building is accepted by the owner. Removal and replacement of
Job No. 113 422A ~tech
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the natural soils to provide at least 4 feet of compacted structural fill below slabs is
recommended to reduce the risk of slab settlement. The structural fill should be
constructed similar to that described above in the "Foundation Alternative" section.
To reduce the effects of some differential settlement, nonstructural floor slabs should be
separated from all bearing walls and columns with expansion joints which allow
unrestrained vertical movement. Floor slab control joinls should be used to reduce
damage due to shrinkage cracking. Slab reinforcement and control joints should be
established by the designer based on experience and the intended slab use.
A minimum 4 inch layer of base course gravel should be placed immediately beneath
slabs-on-grade. This material should consist of minus 2 inch aggregate with less than
50% passing the No.4 sieve and less than 12% passing the No. 200 sieve. The gravel
will provide slab support and help break capillary moisture rise.
Required fill beneath slabs can consist of the on-site soils or a suitable imported granular
material approved by the geotechnical engineer, excluding topsoil and oversized rocks.
The fill should be spread in thin horizontal lifts, adjusted to at or above optimum moisture
content, and compacted to at least 95% of the maximum standard Proctor density. The
topsoil and loose disturbed soil should be removed and the sub grade moistened and
compacted prior to fill placement.
UNDERDRAlN SYSTEM
Although free water was not encountered within expected excavation depths for the
facilities, 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 and basement areas (if any), be protected from wetting and
hydrostatic pressure buildup by an underdrain system. The buildings with floor slab level
constru~ted near finish exterior grade and crawlspace level (if any) should not have a
perimeter underdrain system.
Job No. 113 422A ~tech
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The drains should consist of drainpipe placed in the bottom of the wall backfill
surrounded above the invert level with free-draining gran,ular 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 I% 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 2 feet deep. In basement areas, an impervious
liner, such as a 30 mil PVC membrane, should be placed beneath the drain gravel in a
trough shape and attached to t11e foundation wall with mastic to prevent wetting of the
bearing soils. An impervious membrane is typically not provided for grade change site
walls.
SITE GRADING
The risk of construction-induced slope instability at the site appears low provided cut and
fill depths are limited. We assume the cut depth for the buildings will not exceed one
level, about 1 0 to 12 feet. Fills should be limited to about 8 to 10 feet deep and not
extend onto the steep cut slope at the north side of the property. Structural embankment
fills should be compacted to at least 95% of the maximum standard Proctor density near
optimum moisture content. Prior to fill placement, the sub grade should be carefully
prepared by removing all vegetation and topsoil and compacting to at least 95% of the
maximum standard Proctor density. The fill should be benched into slopes which exceed
20% grade. Permanent unretained cut and fill slopes should be graded at 2 horizontal to 1
vertical or flatter and protected against erosion by vegetation or other means. The new
facilities should be set back from the top of cut slope at the north side of the propetiy to
not potentially destabilize the cut slope. This office should review site grading plans for
the project prior to construction.
PAVEMENT SECTION
We understand that asphalt pavement is typically proposed for the drives and parking.
Traffic loadings for the paved areas have not been provided. The subgrade soils
encountered at the site are generally low to non-plastic silt and sand which are considered
Job No. 113 422A ~ech
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a fair support for pavement sections. Certain soils, such as the silt and sand soils
encountered on this site, are frost susceptible and could impact pavement performance.
Frost susceptible soils are problematic when there is a free water source. If those soils are
wetted, the resulting frost heave movements can be large and erratic. Therefore,
pavement design procedures assume dry sub grade conditions by providing proper surface
and subsurface drainage.
Based on our experience with similar projects, an 18 kip EDLA of 20 for driveways and 5
for automobile parking, a Regional Factor of2.0, a serviceability index of2.0 and a
sub grade Hveem stabilometer "R" value of 20, we recommend the minimum pavement
section thickness consist of 4 inches of asphalt on 7 inches of base course for driveways
and 3 inches of asphalt on 7 inches of base course for parking areas. As an alternative to
asphalt pavement and in areas where truck turning movements are concentrated, the
pavement section can consist of 6 inches of Portland cement concrete on 4 inches of base
course. Once traffic loadings are better known, we should review our pavement section
recommendations.
The section thicknesses assume structural coefficients of 0.14 for aggregate base course,
0.44 for asphalt surface and design strength of 4,500 psi for Portland cement concrete.
The material properties and compaction should be in accordance with the project
specifications.
Required fill to establish designsubgrade level can consist of the on-site soils or suitable
imported granular soils approved by the geotechnical engineer. Prior to fill placement the
sub grade should be stripped of topsoil, scarified to a depth of 8 inches, adjusted to near
optimum moisture content and compacted to at least 95% of standard Proctor density. In
soft or wet areas, the sub grade may require drying or stabilization prior to fill placement.
A geogrid and/or subexcavation and replacement with aggregate base soils may be
needed for the stabilization. The sub grade should be proofrolled. Areas that deflect
excessively should be corrected before placing pavement materials. The sub grade
improvements and placement and compaction of base and asphalt materials should be
monitored on a regular basis by a representative of the geotechnical engineer.
Job No. 113 422A ~tech
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SURFACE DRAINAGE
The following drainage precautions should be observed during construction and
maintained at all times after the facilities have 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 buildings 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 2\1, inches in the first 10 feet in paved areas.
4) Roof downspouts and drains should discharge well beyond the limits of all
backfill and at least 5 feet.
5) Landscaping which requires regular heavy irrigation should be located at
least 10 feet from foundation walls. Preferably, xeriscape should be used
to limit potential 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 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
Job No. 113 422A ~tech
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conditions may not become evident unti l excavation is performed. If conditions
encountered during construction appear to be different from those descr ibed 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 evo lve s, we shoulu pruviue 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 of pier drilling, excavations and
foundation bearing strata and testing of structural fill by a representative of th e
geotechnical engineer.
Respectfully Submitted,
HEPWORTH-PAWLAK GEOTECHNICAL, INC.
Steven L. Pawl ak, P.E.
Reviewed by:
Daniel E. Hardin, P .E.
SLP/ksw
cc: SGM, Inc.-Bill Swigert (bill~(a1 sgm-inc.com)
SGM, Inc .-Andrew Rapiejko (:lllure\\ R(iusgm-inc .~t)m)
A4 Architects-Michael Hassig (mh;1sstg(iva··ktrchitects.com )
Job N o. 11 3 422A ~tech
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REFERENCE
Lincoln-DeVore, 1978, Geologic Hazards of the Glenwood Springs Metropolitan Area,
Garfield County, Colorado, Colorado Geological Survey Open File Report 78-10.
Job No. 113 422A ~tech
113 422A
APPROXIMATE SCALE
1" = 150'
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HEPWORTH-PAWLAK GEOTECHNICAL
PROPOSED
BROADBAND
BUILDING
PROPOSED
ELECTRICAL
OPERATIONS
BUILDING
LOCATION OF EXPLORATORY BORINGS FIGURE 1
5720
5715
5710
c
0
B > Q) w 5705
.<::
0.
Q)
0
5700
5695
5690
5685
113 422A
BORING 1
ELEV.= 5714'
BROADBAND
FF = 5714.5'
9/12
WC=6.5
DD=108
16/12
WC=4.1
DD=107
-200=40
62/12
32/12
58/12
92/12
BORING 2
ELEV.= 5718'
BORING3
ELEV. = 5712"
ELECTRICAL OPERATIONS
FF = 5715.5'
20/12
17/12
WC=4.4
DD=104
15/12
WC=3.6
DD=111
33/12 {j}
-200=41
16/6,20/4
48/12
WC=4.3
DD=121
-200=48 35/12
50/3
50/7
99/12
Note: Explanation of symbols is shown on Figure 4.
BORING4
ELEV. = 5719'
30/12
29/12
WC=2.7
DD=112
46/12
WC=2.9
DD=122
-200=44
50/5
~tech LOGS OF EXPLORATORY BORINGS
HEPWORTH•PAWLAK GEOTECHNICAL
5720
5715
5710
c
0
~ > 5705 Q) w
.<::
0.
Q)
0
5700
5695
5690
5685
Figure 2
5720
5715
c
0 5710
~ > Q)
ill
.c
1i
Q)
0 5705
5700
5695
113 422A
BORINGS
ELEV. = 5719'
29/12
WC=1.9
00=113
-200=35
43/12
WC=0.8
00=106
.,8;
38/12
50/3
BORING6
ELEV.= 5717'
16/12
20/12
WC=3.7
00=113
22112
WC=5.7
00=119
-200=40
50/1
BORING 7
ELEV.= 5717'
12/12
WC=3.0
00=98
-200=54
19/12
Note: Explanation of symbols is shown on Figure 4.
BORINGS
ELEV.= 5715'
BROADBAND
5720
5715
ELEV.= 5714.5'
14/12
WC=10.0
00=115
-200=43
NP 5710
11/6,15/4
5705
5700
5695
c
0
-~
> Q)
ill
%
" 0
~ech LOGS OF EXPLORATORY BORINGS Figure 3
HEPWORTH·PAWLAK GEOTECHNICAL.
LEGEND:
TOPSOIL; organic sandy silt, dark red-brown.
SAND AND SILT (SM-ML); scattered gravel to gravelly, loose to medium dense, slightly moist, red, roughly
stratified.
SAND AND GRAVEL (SM-GM); silty to very silty, scattered cobbles, medium dense, slightly moist, red, roughly
stratified.
GRAVEL, COBBLES AND BOULDERS (GM-GP); slightly silty, sandy, dense, moist to wet with depth at Borings 1
and 3, brown, rounded river rock.
9/12
0,6
T
NOTES:
Relatively undisturbed drive sample; 2-inch I. D. California liner sample.
Drive sample; standard penetration test (SPT), 1 3/8 inch I. D. split spoon sample, ASTM D-1586.
Drive sample blow count; indicates that 9 blows of a 140 pound harnrner falling 30 inches were
required to drive the California or SPT sarnpler 12 inches.
Free water level in boring and number of days following drilling measurement was taken.
Depth at which boring had caved when checked on December 2, 2013.
Practical drilling refusal.
1. Exploratory borings were drilled on November 26, December 2 and 3, 2013 with 4-inch diameter continuous flight
power auger.
2. Locations of exploratory borings were measured approximately by pacing from features shown on the site plan
provided.
3. Elevations of exploratory borings were obtained by interpolation between contours shown on the site plan provided.
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 transitions may be gradual.
6. Water level readings shown on the logs were made at the time and under the conditions indicated (Borings 1 and
3). Fluctuations in water level may occur with tirne.
7. Laboratory Testing Results:
WC = Water Content(%)
DO = Dry Density (pel)
-200 = Percent passing No. 200 sieve
NP = Non-Plastic
113 422A G~
Hepworth-Pawlak Geotechnical
LEGEND AND NOTES Figure 4
Moisture Content = 6.5 percent
Dry Density = 108 pel
Sample of: Sandy Silt
From: Boring 1 at 2 Feet
0
-
1
~
("'_ v Compression
"""
upon
* 2 wetting
c ~ 0 ·u;
(/)
~ 3
D. \ E
0 u
4
\
5 1\
6
0.1 1.0 10 100
APPLIED PRESSURE -ksf
113 422A G~ SWELL-CONSOLIDATION TEST RESULTS Figure 5
H~worth-Powlak Geotechnical
Moisture Content = 4.4 percent
Dry Density = 104 pel
Sample of: Very Silty Sand
From: Boring 2 at 9 Feet
0
t--
1
Compression
-------17 upon
If-2 wetting
c ~ (_ / 1---
0 v ·u;
en 3 ~
Q_
E
0
0
4
5 \
6 \
\
7
8 \
9 \
10 \
11
0.1 1.0 10 100
APPLIED PRESSURE-ksf
113 422A ~~ SWELL-CONSOLIDATION TEST RESULTS Figure 6
H~I!'!Vorth-Pawlck Geotechnical
Moisture Content = 2.7 percent
Dry Density = 112 pel
Sample of: Silty Clayey Sand
From: Boring 4 at 9 Y, Feet
0
*' ~ ""' c 1 0 ·c;; \ \ 1\ c
"' 0.
X w 2
' Expansion 1\ c
0 upon ·c;;
"' 3 wetting Q)
0.
E
0
(_)
4
0.1 1.0 10 100
APPLIED PRESSURE-ksf
113 422A c~
HeD'Worth-Powlak Geotechnical
SWELL-CONSOLIDATION TEST RESULTS Figure 7
Moisture Content = 0.8 percent
Dry Density = 106 pel
Sample of: Very Silty Sand
From: Boring 5 at 9 Feet
0
1
Compression
upon
* 2 -----I) I--wetting
y v v c c_ v 0 ·u;
w 3 !'!
0.
E
0
0
4
5
6 \
7 \
8 f\
\
9 f\
[\
10
0.1 1.0 10 100
APPLIED PRESSURE-ksf
113 422A c~ He~orth Pawlak Geotechnlcol
SWELL-CONSOLIDATION TEST RESULTS Figure 8
Moisture Content = 3.7 percent
Dry Density = 113 pel
Sample of: Silty Sand
From: Boring 6 at 10 Feet
0
* /" ~ p
c 1
0 ~ 1-Compression ·c;;
"' ~ upon Q) wetting 0. 2 E "" 0 i"l u
3
0.1 1.0 10 100
APPLIED PRESSURE-ksf
113 422A Hc&i -CeNtech He~orth Pawlak Geotechnical
SWELL-CONSOLIDATION TEST RESULTS Figure 9
HEPWORTH-PAWLAK GEOTECHNICAL, INC.
TABLE 1 Job No. 113422A
SUMMARY OF LABORATORY TEST RESULTS
SAMPLE LOCATION NATURAL GRADATION ATTERBERG LIMITS UNCONFINED
MOISTURE NATURAL PERCENT
DRY DENSITY GRAVEL SAND PLASTIC COMPRESSIVE SOIL OR BORING DEPTH CONTENT PASSING NO. LIQUID LIMIT STRENGTH
(%) (%) ZOO SIEVE INDEX BEDROCK TYPE
(It) (%) (pel) (%) (%) (PSF)
1 2 6.5 108 Sandy Silt
5 4.1 107 40 Very Silty Sand
2 9 4.4 104 Very Silty Sand
14 4.3 121 48 Very Silty Sand
3 5 3.6 111 41 Very Silty Sand
4 91h 2.7 112 Silty Clayey Sand
14 1/z 2.9 122 44 Very Silty Sand
5 4 1.9 113 35 Silty Sand
9 0.8 106 Very Silty Sand
6 10 3.7 113 Silty Sand
15 5.7 119 40 Very Silty Sand
7 4 3.0 98 54 Very Sandy Silt
8 Jl/z 10.0 115 43 NP Very Silty Sand