HomeMy WebLinkAboutSubsoils Report for Foundation Designffi GTLITHOMPSON
GEOTECHNICAL ENGINEERING INVESTIGATION
214 CENTER DRIVE
(a.k.a. Parcel 2185061 00A421
GARFIELD COUNTY, COLORADO
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Prepared for:
GLENWOOD PARTNERSHIP, LLLP
214 Center Drive
Glenwood Springs, CO 81601
Attention:
John Diemoz
Floyd Diemoz
Project No. GS06693.000-1 25
August 22,2022
CTllThompson. lnc.
DCnye{, Fort Collins, Colorado Sprinqs, Glenwood Sprinqs,.&b!o,, Sunrrnit County - Colorado
Chevenne, Wyoming and Bozeman, Montana
Fou'nded in 1971
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TABLE OF CONTENTS
scoPE.......
SUMMARY OF CONCLUSIONS .,.-
SITE CONDITIONS
PROPOSED CONSTRUCTION .....
SUBSURFACE CONDITIONS........
EARTHWORK.................
Site Grading
Excavations
Subexcavation and Structural Fill
Utility Trench Backfill
Foundation Wall Backfill
FOUNDATIONS..............
Footings on Structural Fill (consisting of on-site clay)............^......
Footings on Structural Fill (consisting of aggregate base course)
SLAB-ON-GRADE FLOORS
BELOW-GRADE CONSTRUCTION .
SURFACE DRAINAGE
CONCRETE
PAVEMENTS.................
CONSTRUCTION OBSERVATIONS
GEOTECHNICAL RISK
LtMtTAT|ONS ................
FIGURE 1_VICINITY MAP
FIGURE 2 -AERIAL PHOTOGRAPH
FIGURE 3 _ PROPOSED DEVELOPMENT
FIGURES 4 AND 5 _ SUMMARY LOGS OF EXPLORATORY BORINGS
FIGURES 6 THROUGH 8 _ SWELL-CONSOLIDATION TEST RESULTS
TABLE I - SUMMARY OF LABORATORY TESTING
APPENDIX A - PAVEMENT MATERIALS AND CONSTRUCTION RECOMMENDATIONS
GLENWOOD PARTNERSHIP, LLLP
214 CENTER DRIVE
GTLIT PROJECT NO. GSo6693.000-125
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SCOPE
CTllThompson, lnc. (CTLIT) has completed a geotechnical engineering in-
vestigation regarding 214 Center Drive (a.k.a. Parcel 218506100042) in Garfield
County, Colorado. We conducted this investigation to evaluate subsurface condi-
tions at the site and provide geotechnical engineering recommendations for the
proposed development. Our report was prepared from data developed from our
field exploration, laboratory testing, engineering analysis, and our experience with
similar conditions. This report includes a description of the subsurface conditions
encountered in our exploratory borings and provides geotechnical engineering rec-
ommendations for design and construction of the proposed development. A sum-
mary of our conclusions is below.
SUMMARY OF CONCLUSIONS
Subsoils encountered in our exploratory borings drilled at the site
consisted of approximately 8 inches of sandy clay topsoil over 13 to
33 feet of sandy clay. Silty gravel with scattered cobbles was found
below the sandy clay at depths of 14 to 32 feet in seven of our bor-
ings. Groundwater was not found in our exploratory borings at the
time of drilling.
We judge that buildings at the site can be constructed on footing
foundations, provided the soils are subexcavated to a depth of 18
inches below bottom of footing elevations. The subexcavated soil
should be replaced with densely-compacted, structuralfill. Recom-
mendations for subexcavation and structuralfill are in the report.
Ground levelfloors in the buildings are planned as slabs-on-grade.
Building floor slabs should be supported by an 18-inch thickness of
densely-compacted, structu ral fill to enhance potential performance
Additional discussion is in the report.
Design pavement section alternatives for the project include 6.5
inches of full-depth asphalt concrete, 4 inches of asphalt concrete
GLENWOOD PARTNERSHIP, LLLP
214 CENTER DRIVE
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cTLlr PROJECT NO. GS06693.000-{25
over 6 inches ef eggregate base course, and 6 inches of Portland ce-
ment. Recommendatbns for pavement materials and construction
are provided.
Site grading should he designed and constructed to rapidly convey
surface water off pauements and away from the buildings.
SITE CONDITIONS
The property addressed m 214 Center Drive (a.k.a. Parcel 2185061 0A042)
is southeast of the intersection of Donegan Road and Storm King Road in Garfield
County, Colorado. Center Drive,lfrte Glenwood Business Center, and the Glen-
wood Springs Mall are to the souttr- A vicinity map with the location of the site is
included as Figure 1. Existing sirgb-family residences and commercial buildings
are adjacent to the east property boundary. An aerial photograph of the site is
shown on Figure 2. Ground surfae on the property generally slopes down to the
south at grades of less than 5 perent. The parcel is predominantly irrigated pas-
ture. Numerous irrigation ditch labrals are present on the property. A photograph
of the site at the time of our subsurfiace investigation is below.
Looking east from Storm King Road
GLENWOOD PARTNERSHIP, LLLP
214 CENTER DRIVE
CTLIT PROJECT NO. GS06693.000-{25
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PROPOSED CONSTRUCTION
CTLIT was provided with a Site Master Plan developed by Glenwood Part-
nership, LLLP (dated August 8,2021). A total of nine buildings are planned as
shown on Figure 3. The buildings are envisioned as one-story and two-story struc-
tures that will be used for combined office and warehouse use. The buildings will
likely be steel-framed. Ground-level floors in the buildings are planned as slabs-
on-grade. No below-grade areas, such as basements or crawl spaces, will be con-
structed. We expect that site grading will involve cut depth and fill thickness of less
than 5 feet. We should be provided with civil engineering plans and architectural
plans, as they are further developed, so that we can provide geotechnical/geo-
structural engineering input.
SUBSURFACE CONDITIONS
CTLIT investigated subsurface conditions by drilling nine exploratory bor-
ings at the site. The borings were drilled on April 21 and 22,2022, with a track-
mounted drill rig and solid-stem auger at the approximate locations shown on Fig-
ures 2 and 3. Exploratory drilling operations were directed by our engineer, who
logged subsurface conditions encountered and obtained representative samples of
the soils. Graphic logs of the soils found in our exploratory borings are shown on
Figure 4.
Subsoils encountered in our exploratory borings consisted of approximately
8 inches of sandy clay topsoil over 13 to 33 feet of sandy clay. Silty gravel with
scattered cobbles was found below the sandy clay at depths of 14 to 32 feet in
seven of our borings. The maximum depth of our borings was 34 feet. Groundwa-
ter was not found in our exploratory borings at the time of drilling. PVC pipe was
installed in the borings, prior to backfilling, to facilitate subsequent checks of
groundwater. Near-surface groundwater seepage had filled the pipes in four of our
GLENWOOD PARTNERSHIP, LLLP
214 CENTER DRIVE 3
cTLIT PROJECT NO. G506693.000-t2s
borings to depths of 11.5 feet to 25 feet when they were checked on August 15,
2022. The seepage may be due to flood irrigation, which commenced after drilling
Samples of the soils obtained from our exploratory borings were returned to
our laboratory for pertinent testing. Five samples selected for one-dimensional,
swell-consolidation testing exhibited volume change ranging from 0.4 percent
swell to 0.1 percent consolidation when wetted under a load of 1,000 psf. Engi-
neering index testing on three samples of the soils indicated liquid limits of 30 to
33, plasticity indices of 13 to 16 percent, and 66 to 82 percent silt and clay (pass-
ing No. 200 sieve). Two samples of the soil tested contained 0.00 percent water-
soluble sulfates. Swell-consolidation tests results are shown on Figures 6 through
B. Laboratory testing is summarized on Table L
EARTHWORK
We expect that site grading will involve cut depth and fill thickness of less
than 5 feet. Excavation depths to construct the building foundations are expected
to be less than 4 feet below ground surface after site grading is completed.
Site Gradinq
Areas that will receive fill should be stripped of vegetation and organic soils
Stripping depths of 6 to 12 inches should be expected across most of the site. lrri-
gation ditch laterals that will be abandoned should be qraded and filled to ensrrre
that seepage flow does not occur.
After stripping is accomplished, the resulting ground surface in areas that
will receive fill should be scarified to a depth of at least 6 inches, moisture-treated,
and compacted. Soft areas should be reworked or otherurise stabilized prior to
placing fill. The on-site soils are suitable for reuse as overlot fill, provided rocks
GLENWOOD PARTNERSHIP, LLLP
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larger than 6 inches in diameter, organics, and debris are removed. Grading fill
should be placed in maximum 10-inch thick lifts, moisture-conditioned to within 2
percent of optimum moisture content, and compacted to at least 95 percent of
standard Proctor (ASTM D 698) maximum dry density. Placement and compaction
of fill should be observed and tested by CTLIT during construction.
Excavations
Our subsudace investigation indicates that excavations at the site can be
accomplished with conventional, heavy-duty excavation equipment. The natural
clay soil at the site will likely classify as Type B based on OSHA standards govern-
ing excavations. Temporary slopes deeper than 5 feet and above groundwater
should be no steeper than 1 to 1 (horizontal to vertical) in Type B soils. Contrac-
tors are responsible for site safety and providing and maintaining safe and stable
excavations. Contractors should identify the soils encountered in excavations and
ensure that OSHA standards are rnet.
We do not expect that excavations for the proposed construction (less than
4 feet deep) will penetrate the free groundwater table. Excavations should be
sloped to gravity discharges or to temporary sumps where water from precipitation
can be removed by pumping.
Subexcavation and Structural Fill
Our subsurface information indicates the undisturbed, natural clay soil has
potential for volume change ranging from low swell to low consolidation when wet-
ted. We judge that buildings at the site can be constructed on footing foundations,
provided the soils are subexcavated to a depth of at least 18 inches below bottom
of footing elevations. Building floor slabs should be suppotled by an 1B-inch thick-
ness of densely-compacted, structural fill to enhance potential performance.
GLENWOOD PARTNERSHIP, LLLP
2{4 CENTER DRIVE
CTLIT PROJECT NO. GS06693.000-125
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The subexcavated soils should be replaced with densely-compacted, struc-
tural fill. The on-site soils can be used as structuralfill, provided they are free of
rocks larger than 3 inches, organics, and debris. A positive alternative would be to
import a CDOT aggregate base course or similar soilfor use as structuralfill. This
would result in higher bearing capacities for footings and enhanced performance
of footings and floor slabs.
Structural fill should be placed in loose lifts of 8 inches thick or less, mois-
ture-conditioned to within 2 percent of optimum moisture content, and compacted
to at least 98 percent of standard Proctor (ASTM D Ggs) maximum dry density,
Moisture content and density of structural fill should be checked by CTLIT during
placement. Observation of the compaction procedure is necessary.
Utilitu Tre ch Backfill
Underground utilities for the project will likely be constructed below areas.of
pavements and exterior concrete flatwork. Gompaction of trench backfill will have
a significant effect on the life and serviceability of these structures. lmproper com-
paction of trench backfill can cause backfill materials to consolidate leading to po-
tentially severe deformation of pavements and damage to concrete slabs. The on-
site soils free of rocks larger than 4 inches in diameter, organics, and debris can
be used as utility trench backfill.
Trench backfill should be placed in loose lifts of 10 inches thick or less,
moisture-conditioned to within 2 percent of optimum moisture content and com-
pacted to at least 95 percent of standard Proctor (ASTM D698) maximum dry den-
sity. Special care is needed for backfill adjacent to manholes and vertical riser
pipes. Placernent and compaction of backfill should be observed and tested by our
firm during construction.
GLENWOOD PARTNERSHTP, LLLP
214 CENTER DRIVE
cTLIT PROJECT NO. GS06693.000-125
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Foundation Wall Backfill
Proper placement and compaction of foundation wall backfill is important to
reduce infiltration of surface water and settlement from consolidation of the backfill
soils. The soils excavated from the site can be used as backfill, provided they are
free of rocks larger than 4-inches in diameter, organics, and debris.
Backfill should be placed in loose lifts of approximately 10 inches thick or
less, moisture-conditioned to within 2 percent of optimum moisture content, and
compacted to at least 95 percent of standard Proctor (ASTM D 698) maximum dry
density. Our representative should test moisture content and density of the backfill
during placement.
FOUNDATIONS
Our subsurface information indicates the natural clay soil has potentialfor
volume change ranging from low swellto low consolidation when wetted. We
judge that the buildings at the site can be constructed on footing foundations, pro-
vided the soils are subexcavated to a depth of at least 18 inches below bottom of
footing elevations. The subexcavated soil should be replaced with densely-com-
pacted, structural fill. The structuralfill should be in accordance with recommenda-
tions in the Subexcavation and Structural Fill section. Structuralfill consisting of
imported aggregate base course would allow footings with higher bearing pres-
sures, as compared to structural fill consisting of the on-site clay soil.
Recommended design and construction criteria for footings are below.
These criteria were developed based on our analysis of field and laboratory data,
as well as our engineering experience.
GLENWOOD PARTNERSHIP, LLLP
214 CENTER DRIVE
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Footings on Structural Fill (consistinq of on-site clav)
Footings supported on an 1B-inch thickness of densely-ompacted,
structural fill consisting of the on-site clay can be designed for a max-
imum net allowable soil bearing pressure of 2,000 psf- The weight of
backfill above the footings can be neglected for bearing capacity cal-
culations. The structural fill should be in accordance wilh recommen-
dations in the Subexcavation and Structural Fill section-
A friction factor of 0.35 can be used to calculate resistane to sliding
between the concrete footings and structural fill consisliinqg of the on-
site clay soil.
Continuous wall footings should have a minimum width of at least 20
inches. Foundations for isolated columns should have minimum di-
mensions of 30 inches by 30 inches. Larger sizes may he required,
depending upon foundation loads.
Grade beams and foundation walls should be well-reinforced. We
recommend reinforcement sufficient to span an unsupputed dis-
tance of at least 12 feet.
The soils under exterior footings should be protected frqn freezing.
We recommend the bottom of footings be constructed at least 36
inches below finished exterior grades. The Garfield County building
department should be consulted regarding frost protection require-
ments.
Footings supported on an 18-inch thickness of densely-ompacted,
structural fill consisting of imported aggregate base course can be
designed for a maximum net allowable soil bearing pressure of 3,000
psf. The weight of backfill above the footings can be negbcted for
bearing capacity calculations. The structuralfill should be in accord-
ance with recommendations in the Subexcavation and Sfuuctural Fill
section.
2.A friction factor of 0.40 can be used to calculate resistane to sliding
between the concrete footings and structuralfill consislirng of im-
ported aggregate base course.
GI-E NIA'OOD PARTNERSHIP, LLLP
2I{ CENTER DRIVE
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Footinqs on Structural Fill (consisting of aqqreqate base coursel
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GILIT PROJECT NO. GS06593.000-t25
Continuous wall footings should have a minimum width of at least 16
inches. Foundations for isolated columns should have minimum di-
mensions of 24 inches by 24 inches. Larger sizes may be required,
depending upon foundation loads.
Grade beams and foundation walls should be well-reinforced. We
recommend reinforcement sufficient to span an unsupported dis-
tance of at least 12feet.
The soils under exterior footings should be protected from freezing.
We recommend the bottom of footings be constructed at least 36
inches below finished exterior grades. The Garfield County building
department should be consulted regarding frost protection require-
ments.
SLAB.ON-GRADE FLOORS
Ground level floors in the buildings are planned as slabs-on-grade. The nat-
ural clay soil at the site has potentiat for volume change ranging from low swell to
low cortsolidation when wetted: Building floor slabs should be supported by an 1B-
inch thickness of densely-compacted, structural fill to enhance potential perfor-
mance. The structuralfill should be in accordance with recommendations in the
Subexcavation and Structural Fill section. Structural fill consisting of imported ag-
gregate base course would enhance potential slab performance, as compared to
structural fill consisting of the on-site clay soil.
Based on our analysis of field and laboratory data, as well as our engineer-
ing experience, we recommend the following precautions for slab-on-grade con-
struction at this site.
Slabs should be separated from wallfootings and column pads with
slip joints, which allow free vertical movement of the slabs.
Underslab plumbing should be pressure tested for leaks before the
slabs are constructed. Plumbing and utilities which pass through
GLENWOOD PARTNERSHIP, LLLP
2{4 CENTER DRIVE
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cTLlr PROJECT NO. GSo6693.000-125
slabs should be isolated from the slabs with sleeves and provided
with flexible couplings to slab supported appliances.
Exterior concrete flatwork should be isolated from the buildings.
These slabs should be well-reinforced to function as independent
units.
Frequent controljoints should be provided, in accordance with Amer-
ican Concrete lnstitute (ACl) recommendations, to reduce problems
associated with shrinkage and curling.
The lnternational Building Code (lBC) may require a vapor retarder
be placed between the subgrade soils and concrete slab-on-grade
floors. The merits of installation of a vapor retarder below floor slabs
depend on the sensitivity of floor coverings and building to moisture.
A properly installed vaper retarder (10 mil minimum) is more benefi-
cial below concrete slab-on-grade floors where floor coverings will be
sensitive to moisture.
BELOW.GRADE CONSTRUCTION
We understand the buildings will not be constructed with below-grade ar-
eas, such as basements or crawl spaces. lf construction plans evolve to include
below-grade areas, we should be informed so that we can provide recommenda-
tions for lateral earth pressures and subsurface drainage systems.
SURFACE DRAINAGE
Surface drainage is critical to the performance of foundations, floor slabs,
and concrete flatwork. Site grading should be designed and constructed to rapidly
convey surface water away from the buildings. Proper surface drainage and irriga-
tion practices can help control the amount of surface water that penetrates to foun-
dation levels and contributes to settlement or heave of soils that support founda-
tions and slabs-on-grade. Positive drainage away from the foundation and avoid-
GLENWOOD PARTNERSHIP, LLLP
214 CENTER DRIVE
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ance of irrigation near the foundation also help to avoid excessive wetting of back-
fill soils, which can lead to increased backfill settlement and possibly to higher lat-
eral eadh pressures, due to increased weight and reduced strength of the backfill.
We recommend the following precautions.
The ground surface surrounding the exterior of the buildings should
be sloped to drain away from the buildings in all directions. We rec-
ommend a minimum constructed slope of at least 12 inches in the
first 10 feet (10 percent) in landscaped areas around the buildings.
2. Backfill around the foundation walls should be moisture-treated and
compacted pu rsuant to recommendations in the Foundation Wa
Backfill section.
The buildings should be provided with roof drains or gutters and
downspouts. Roof downspouts and drains should discharge well be-
yond the limits of all backfill. Splash blocks and/or extensions should
be provided at all downspouts so water discharges onto the ground
beyond backfill zones.
Landscaping should be carefully designed and maintained to mini-
mize irrigation. Plants placed close to foundation walls should be lim-
ited to those with low moisture requirements. Sprinklers should not
discharge within 5 feet of foundations. Plastic sheeting should not be
placed beneath landscaped areas adjacent to foundation walls or
grade beams. Geotextile fabric will inhibit weed growth yet still allow
natural evaporation to occur.
CONCRETE
Concrete in contact with soil can be subject to sulfate attack. We measured
water-soluble sulfate concentrations of 0.00 percent in two samples of the soil
from the site (see Table l). For this level of sulfate concentration, ACI 318-08,
"Code Requirements for Structural Concrete", indicates there are no special ce-
ment requirements for sulfate resistance in concrete that is in contact with the sub-
soils.
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2{4 CENTER DRIVE
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ln our experience, superficial damage may(rccur to the exposed surfaces of
highly permeable concrete. To control this risk and to resist freeze thaw deteriora-
tion, the water-to-cementitious materials ratio shouH not exceed 0.50 for concrete
in contact with soils that are likely to stay moist drre to surface drainage or high-
water tables. Concrete should have a total air content of 6% +l-1.5o/o.
PAVEMENTS
Based on the AASHTO Classification systenr" we estimate the natural soils
and densely-compacted, site grading fill constru@d with the on-site soils will clas-
sify as AASHTO Group A-6. We estimate a resilient modulus (Mn) of 5,000 psi
based on our experience with similar soils.
Traffic loading numbers were not available atthis writing. We assume pave-
ments will be primarily subject to automobile traffic- Some.heavy truck traffic, such
as garbage trucks, may occur in some areas. We estimated an Equivalent Single
Axle Load (ESAL) value of 200,000 for the pavernents. We should be provided
with design traffic numbers when available so thatwe can review and/or refine our
recommendations. Our recommend minimum palrernent section alternatives are
shown in Table 1 below.
Table 1
Recommended Pavement Sedion Alternatives
GLENWOOD PARTNERSHIP, LLLP
2I4 CENTER DRIVE
Design Traffic-
Loading
(ESAL)
Asphalt Concrete
(AC)
AsphaltGoncrete +
Aggrqate Base
Course
(AG + ABC)
Portland Cement
Concrete
(Pcc)
200,000 6.5'AC 4.0'AC + 9.0" ABC 6.0'PCC
CTLIT PROJECT NO. cS06693.000-125
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Pavement performance can be problematic in areas wtnere heavy trucks
turn and stop, such as entrances and dumpster pads. ln arem subject to traffic by
heavy trucks, we recommend the client consider Portland oerrnent concrete pave-
ment that is at least 6 inches thick.
The performance of a pavement system depends on tfrre quality of the pav-
ing materials and construction, as well as the support charatrrbtics of the sub-
grade soils. lf the pavement system is constructed of inferior rnaterial, then the life
and serviceability of the pavement will be substantially redud- We have included
material and construction recommendations for flexible and rigFd pavements in the
attached Appendix A.
A primary cause of early pavement deterioration is wabinfiltration into the
pavement system. The addition of moisture usually results in softening of the sub-
grade soils and eventual failure of the pavement. We recomrnend drainage be de-
signed for rapid removal of surface runoff from pavement surf;aoes. Final grading
should be carefully controlled so that design cross-slope is mailntained and low
spots in the subgrade which could trap water are eliminated, Portland cement con-
crete drainage pans should be considered in areas where water will be flowing
across pavement surfaces.
CONSTRUCTION OBSERVATIONS
We recommend that CTL Thompson, lnc. be retained to provide construc-
tion observation and materials testing services for the project" This would allow us
the opportunity to verify whether soil conditions are consistentwith those found
during this investigation. lf others perform these observations" frrey must accept
responsibility to judge whether the recommendations in this report remain appro-
priate. lt is also beneficialto projects, from economic and pradfical standpoints,
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214 CENTER DRIVE
CTLIT PROJECT NO. G506693.000-125
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when there is continui$ hetween engineering consultation and the construction
observation and materiah testing phases.
GEOTECHNICAL RISK
The concept of tisk is an important aspect of any geotechnical evaluation.
The primary reason forthis is that the analytical methods used to develop ge-
otechnical recommendalbns do not comprise an exact science. We never have
complete knowledge of subsurface conditions. Our analysis must be tempered
with engineering judgrnemt and experience. Therefore, the recommendations in
any geotechnical evaluatbn should not be considered risk-free and are not a guar-
antee that the interac{iorn between the soils and the proposed structure will lead to
performance as desired or intended. Our rebommendations in the preceding sec-
tions constitute our estinnate of those measures that are necessary to help the
buildings perform satisftctorily. lt is critical that all recommendations in this report
are followed.
This report has been prepared for the exclusive use of the client. The infor-
mation, conclusions, and recommendations presented herein are based upon con-
sideration of many facfions including, but not limited to, the type of structures pro-
posed, the geologic seffinrg, and the subsurface conditions encountered. The con-
clusions and recommendations contained in the report are not valid for use by oth-
ers. Standards of pradhe continuously change in geotechnical engineering. The
recommendations provftded in this report are appropriate for about three years. lf
the proposed project is rnot constructed within three years, we should be contacted
to determine if we shouH update this report.
GLENWOOD PARTNERSHIP, LLLP
214 CENTER DRIVE
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LIMITATIONS
Our exploratory borings provide a reasonable characferization of subsur-
face conditions at the site. Variations in the subsurface corditions not indicated by
borings will occur. We should be provided with civil engirreering and architectural
plans, as they are further developed, so that we can provitie geotechnical/geo-
structural engineering input.
This investigation was conducted in a manner consistent with that level of
care and skill ordinarily exercised by geotechnical engineers currently practicing
under similar conditions in the locality of this project. No warranty, express or im-
plied, is made. lf we can be of further service in discussirqg the contents of this re-
port, please call.
crllTH o Rwbwed by:
Mechling, P.E D. Kellogg
nior Principle Engineer Manager
o
0
Sezgs
g
GLENWOOD PARTNERSHIP, LLLP
214 CENTER DRIVE
CTLIT PROJECT NO. GS06693.000-r25
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PROJECT rrp. GSO6693.OOO-1 25
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GLENWOOD PARTNERSHIP, LLLP
214 CENTER DRIVE
PROJECT NO. GS06693.000-1 25
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FIG. 4
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LEGEND:
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TOPSOIL, CLAY, SANDY, MOIST, BROWN
CLAY, SANDY, MED|UIM STIFF TO VERY ST|FF. n4OSr" BROWN. (CL)
GRAVEL, SrLTy, SCATTERED COBBBLES, MEDlrtrtmNSE TO DENSE, MO|ST, BROWN. (eM)
DRIVE SAMPLE. THE SYMBOL 7/12 INDICATES 7 tstJOWS OF A 14o-POUND HAMMER FALLING
30 INCHES WERE REQUIRED TO DRIVE A 2.s-II{CITIICD"D. CALIFORNIA-BARREL SAMPLER 12
INCHES.
T PRACTICAL AUGER REFUSAL
g INDICATES LEVEL TO WHICH NEAR-SURFACE GR(XMIDWATER SEEPAGE HAD
FILLED PIPE WHEN CHECKED ON AUGUST 15.2fi8',TTIIS SEEPAGE OCCURRED
AFTER FLOOD IRRIGATION COMMENCED ATftESTf,E-
NOTES:
1 , EXPLOMTORY BORINGS WERE DRILLED ON APRIL zII AND 22, 2022 WITH A
TMCK-MOUNTED RILL RIG AND 4-INCH DIAMETER,,$oLID-STEM AUGER.
2. GROUNDWATER WAS NOT FOUND IN OUR BORII{GSAT THE TIME OF DRILLING, PVC PIPE
WAS INSTALLED IN OUR BORINGS TO FACILITATESI]ESEQUENT CHECKS OF
GROUNDWATER.
3. THESE LOGS ARE SUBJECT TO THE EXPLANATIOINS,, I-IMITATIONS, AND CONCLUSIONS IN
THIS REPORT.
SUMMARY LEGEND OF EXPLORATORY BORINGS
GLENVVOOD PARTNERSHIP. LLLP
214 CENTER DRIVE
PROJECT NO. GS06693.000-1 25 FIG. 5
ffi
3
2
1
z@oo
={-ro-xrus24.I00utt4o-
=oo4
3
2
1
(lzooz. -r
cxN4szoooEt.L4
=oo s
o.1
APPLIED PRESSURE - KSF
1.0 10
DRY UNITWEIGFIIIF=
MOISTURE CONTENIIF=
110
16.8
10
DRY UN|TWElGllfll=
MOISTURE CONTEINIII=
114
15.2
Swell-Gonsolidation
Test Results
Fio" 6
100
PCF
%
100
PCF
ScNnnple of CLAY, SANDY (CL)
Ftotrn
Filturil
TH-1 AT 9 FEET
0.1
APPLIED PRESSURE. KSF
Sonnple of cLAY, sANDY (cL)
TH-4 AT 9 FEET
GI.EWT'OD PARTNERSHIP, LLLP
2l,tCffiTER DRIVE
PRO.ECT NO- GS06693.000-1 20
/-
EXPANSION U N DER COiISTANT
PRESSURE DUE TO II$IETTING
ttltttiltlllt
I ,
\
)
, EXPANSION UNDER CONSTANT
PRESSU RE DU E TO \4I4ETTI NG
\Fi\
\
t
1.0
ffi
0
-2
zofi-sz
o-X
UJs4zooauJ -)
tr
o-
Eoo€
0.1
APPLIED PRESSURE. KSF
Somple of CLAY SANDY (CL)
From TH4N AT 14 FEET
11.10 10
DRY UNITWEIGHT=
MOISTURE CONTENT=
10
DRY UNITWEIGHT=
MOISTURE CONTENT=
100
108 PCF
o/o13.2
100
103 PCF
tt.l V"
3
2
aooz
O. -rxui
sz.o
6o
UJE-t
o-
Eoo
-4
0.1
APPLIED PRESSURE. KSF
Somple of cLAy, SANDy (cL)
From TH-4S AT 4 FEET
GLENWOOD PARTNERSHlP, LLLP
214 CENTER DRIVE
PROJECT NO. GS06693.000-120
Swell-Consolidation
Test Results
Fiq. 7
\\
.Fl\
- EXPANSION UNDER CONSTANT
PRESSURE DUE TO WETTINGl|lll t l l|r
I
I
)
\
,
r rrlr t I I I I ttt
, EXPAN$ION UNDER CONSTANT
PRESSURE DUE TO WETTING
I
5
\
)
11.(D
ffi
7
6
5
4
3
2
-2
-3
0
$.+
@z
o- -sx
UJ
s
f;-eoo
IIJE-zo.
=oo
-8
0.1
From
10
ffiY UNITWEIGHT=
IUICISTURE CONTENT=
121
12.3
Swell-Consolidation
Test Results
Fig. I
100
PCF
%
APPLIED PRESSURE . KSF
Somple of CLAY, SANDY (CL)
TH.6 AT 9 FEET
GLENWOOD PARTNERSHIP, LLLP
214 CENTER DRIVE
PROJECT NO. GS06693.000-120
\
\
-- ADDITIO|NIAL COMPRESSION UNDER
CONSTAINIT PRESSURE DUE TO-- WETNNG
ltil il il il ll llIl).
\
\
)
1.0
TABLE I
SUMMARY OF LABORATORY TESTING
PROJECT NO. GS06693.000-120
ffi
DESCRIPTION
CLAY. SANDY (CL)
CLAY. SANDY (CL)
CLAY. SANDY (CL)
CLAY. SANDY (CL)
CLAY. SANDY (CL)
CLAY. SANDY (CL)
CLAY. SANDY (CL)
CLAY, SANDY (CL)
CLAY, SANDY (CL)
CLAY. SANDY (CL)
CLAY. SANDY (CL)
CLAY. SANDY (CL)
CLAY, SANDY (CL)
CLAY. SANDY (CL)
CLAY. SANDY (CL}
CLAY. SANDY (CL)
CLAY. SANDY (CL)
CLAY. SANDY (CL)
PASSING
NO.200
SIEVE
(o/a\
77
82
tltr
WATER
SOLUBLE
SULFATES
(d/a\
0.00
0.00
UNCONFINED
COMPRESSION
(PSFI
4.700
16.100
7.600
'SWELL
(ela\
0.1
o.4
0.4
1.1
-o.1
ATTERBERG LIMITS
PLASTICITY
INDEX
(e/6\
16
13
14
LIQUID
LIMIT
(o/"\
33
30
31
DRY
DENSITY
IPCF}
114
111
107
107
100
113
124
105
113
116
113
130
108
119
121
115
'114
109
MOISTURE
CONTENT
(oh\
14.7
16,8
19.7
20.5
25.1
12.3
11.5
20.5
16.6
15.2
13.2
15.3
11.7
10.3
12.3
16.5
15.7
19.4
DEPTH
{FEET)
4
I
4
14
24
4
o
19
4
I
14
19
4
4
o
4
o
14
EXPLORATORY
BORING
TH.1
TH-1
tH-2
TH-2
TH.2
TH-3
TH-3
TH.3
TH4
TH-4
TH-4N
TH4N
TH.4S
THS
TH-6
TH.7
TH:7
TH.7
* SWEtt MEASURED UNDER 1,OOO P€F APPTIED PRESEURE,
NEGATIVE VALUE INDICATES EONSOLIDATION,Page 1 of 1
ffi
APPENDIX A
PAVEM ENT CONSTRUCTION AND MATERIALS RECOMMENDATI ONS
GLENWOOD PARTNERSHIP, LLLP
2I4 CENTER DRIVE
crllT PROJECT NO. GS06693,000-125
ffi
PAVEMENT MATERIALS
Material properties and construction criteria for the pavement al,brnatives
are provided below. These criteria were developed from analysis of the fiieltl and
hhoratory data and our experience. lf the materials cannot meet these remm-
nnendations, then the pavement design should be reevaluated based upon avail-Sb materials. Materials planned for construction should be submitted and the
applicable laboratory tests performed to veriff compliance with the specfrfications.
Asphalt Concrete (AC)
AC should be composed of a mixture of aggregate, filler, @rated
lime and asphalt cement. Some mixes may require polynrermodi-
fied asphalt cement, or make use of up to 25 percent reclaimed as-
phalt pavement (RAP). A job mix desiqn is recommended and peri-
odic checks on the iob site should be made to verifv compfiance
with specifications.
2.AC should be relatively impermeable to moisture and shouH be de-
signed with crushed aggregates that have a minimum of 80 percent
of the aggregate retained on the No. 4 sieve with two mecftanically
fractured faces.
Gradations that approach the maximum density line (within 5 per-
cent between the No. 4 and 50 sieve) should be avoided. Agrada-
tion with a nominal maximum size of 1 or 2 inches develo@ on
the fine side of the maximum density line should be used.
1
3
4.
GIHWOOD PARTNERSHIP, LLLP
2ltdCElrlTER DRIVE
5
6.
Total void content, voids in the mineral aggregate (VMA) anrd voids
filled should be considered in the selection of the optimunn mphalt
cement content. The optimum asphalt content should be sdlected
at a total air void content of approximately 4 percent. The naixture
should have a minimum VMA of 14 percent and between 65 per-
cent and 80 percent of voids filled.
Asphalt cement should meet the requirements of the Superpave
Performance Graded (PG) Binders. The minirnum performforg as-
phalt cement should be PG 58-28.
Hydrated lime should be added at the rate of 1 percent by dry
weight of the aggregate and should be included in the amomt
passing the No. 200 sieve. Hydrated lime for aggregate pldreat-
ment should conform to the requirements of ASTM C 207,Type N
clnllr pRoJEcT No. cs06693.000-125
A-1
ffi
7.
8.
Paving strouH only be performed when subgrade temperatures are
above 4$F and air temperature is at least 40oF and rising.
HMA shoulH not be placed at a temperature lower than 245oF for
mixes conhining PG 58-28 asphalt, and 290oF for mixes containing
polymer rnodifted asphalt. The breakdown compaction should be
completed hefore the mixture temperature drops 20oF.
The maxinmnn compacted lift should be 3.0 inches and joints
should be ffiggered. No joints should be placed within wheel
paths.
HMA should be compacted to 94 + 2 percent of Maximum Theoreti-
cal DensitXr- The surface shall be sealed with a finish roller prior to
the mix dng to 185oF.
I
10
11 Placement and compaction of HMA should be observed and tested
by a representative of our firm. Placement should not commence
untilthe srtrgrade is properly prepared (or stabilized), tested and
proof-rolled- Proof rolling should be performed with the heaviest
machine available at the time. The proof roller should be selected
from macftrirres providing both mass and high contact pressure.
Agqreqate Base Course (ABGI
A Class 6 Colryado Department of Transportation (CDOT) specified
aggregate base course should be used. A recycled concrete alterna-
tive which mS the Class 6 designation is also acceptable.
Aggregate bre course should have a minimum Hveem stabilometer
value of 78. Aggregate base course or recycled concrete material must
be moisture sEble. The change in R-value from 300 psi to 100 psi exu-
dation pressurc should be 12 points or less.
Aggregate base course or recycled concrete should be laid in thin lifts
nofto exceed E inches, moisture treated to within 2 percent of optimum
moisture content, and compacted to at least 95 percent of maximum
modified Procilordry density (ASTM D 1557, AASHTO T 180).
Placement and compaction of aggregate base course or recycle-d con-
crete should be observed and tested by a representative of our firm.
Placement strouH not commence until the underlying subgrade is
properly prepared and tested.
GLENWOOD PARTNERSHIP, LLLP
214 CENTER DRIVE
crLlT PROJECT NO. Gso6693.ooo-f6
1
2.
3
4
A-2
ffi
Portland Gement Concrete Pavement (PCCp)
Portland cement concrete should have a minimum compressive
strength of 4,500 psi at 28 days and a minimum modulus of rupture
(flexural strength) of 650 psi. A CDOT approved Class P mix design
is also acceptable . A iob mix desion is mended and oeriodic
checks on the iob site should be made to verify compliance with
specifications.
2 Normal Type I or Type ll cement may be used in concrete at this
site.
Portland cement concrete should not be placed when the subgrade
or air temperature is below 40oF.
Free water should not be finished into the concrete surface and fin-
ishers should not use a steeltrowel on the surface. Atomizing noz-
zle pressure sprayers for applying finishing compounds are recom-
mended whenever the concrete surface becomes difficult to finish.
Curing of the portland cement concrete should be accomplished by
the use of a curing compound. The curing compound should be ap-
,plied in accordance with manufacturer recommendations.
Curing procedures should be implemented, as necessary, to pro-
tect the pavement against moisture loss, rapid temperature change,
freezing, and mechanical injury.
Construction joints, including longitudinal joints and transverse
joints, should be formed during construction or sawed after the con-
crete has begun to set, but prior to uncontrolled cracking.
Alljoints should be properly sealed using a rod back-up and ap-
proved sealant.
Traffic should not be allowed on the pavement until it has properly
cured and achieved at least 80 percent ot the design strength, with
saw joints already cut.
1
3
4
5
6
7
8
o
10.
GLENWOOD PARTNERSHIP, LLLP
214 CENTER DRIVE
Placement of portland cement concrete should be observed and
tested by a representative of our firm. Placement should not com-
mence untilthe subgrade is properly prepared and tested.
cTLIT pROJECT NO. G506693.000-12s
A-3
tr GTL ITHOMPSON
': r i 1.rlJ:;. , :''
NovemberT,Xn3
Andover Marnagement Group
333 East Maih Street, Suite 300
Louisville, KY ffi202
Attention: Dan Kunau
Subject:Geotechnical Engineering lnvestigation - Addendum
214 Center Drive
(a.k. a. Parcel 218506100042,
Garfield County, Colorado
ATLIT Project No. GS06693.001-125
CTllTltnompson, lnc. (CTLIT) performed a geotechnical engineering investigation regard-
ing214 CentenDrive (a.k.a. Parcel 218506100042)in Garfield County, Colorado. Subsequentto
our report, $re\were asked to prepare this addendum. This letter provides geotechnical engF'
neering recdilrnnendations and design criteria for earth retaining walls, seismic design, and
belled pier foundations.
Site Earth Reilainins Walls
We urderstand site earth retaining walls are included in the current plans for the proiled.
Earth retainitq walls must be designed to resist lateral earth pressures. Many factors affecf frhe
, values of the design lateral earth pressure. These.factors include, but are not limited to, the
type, compadiion, slope, and drainage of the backfill, and the rigidity of the wall against rotatibn
and deflection..
For a very rigid wall where negligible or very little deflection will occur, an "at-resf laferal
earth pressue should be used in design. For walls that can deflect or rotate 0.5 to 1 percent of
wall height (depending upon the backfill types), design for a lower "active" lateral earth pressure
may be appropniate.
For hdldll soils conforming with recommendations in the Foundation Wall Backfillseo-
tion of our rryorrt that are not saturated, we recommend design equivalent fluid densities of d
least 45 pcf armd 60 pcf for the "active" and "at-rest" conditions, respectively. Passive earth ples-
sure calculded with an equivalent fluid pressure of 300 pcf is appropriate for this site, provilded
backfill in fromt of the retaining wall footings will not be removed during the lifespan of the strurc-
tures.
Surfaewaterfrom precipitation and landscape irrigation is likely to infiltrate backfill
placed adjaoernt to site earth retaining walls. This water can cause reduced backfill strengh and
result in hydrosfiatic pressures on the retaining walls. Drains should be constructed behind tfne
bases of the footings for the walls.
CTllThompson. lnc.
Denver, FortCollins, @!.gSpling.9, Glenwood Sprinqs, Pueb!.g,, Summit Countv - Colorado
Cheyenne, Wyoming and Bozeman, Montana
ffi
The earth retaining wall drains can consistof 4-inch diameter, slotted, PVC pipe en-
cased in free-draining gravel. A prefabricated dralrnage composite should be placed adjacent to
the backs of the walls. Care should be taken durirq backfill operations to prevent damage to
drainage composites. The drains should discharge via gravity outlets or weep holes.
Seismic Design Parameters
We expect the proposed buildings will be oornsidered Risk Category ll, pursuant to the
2021 lBC. The soil and bedrock are not expected to respond unusually to seismic activity, and
they have low susceptibility to liquefaction. Pursuanfrto the ASCE/SEI 7-22 and our subsurface
information, we judge that Site Soil Class D is appnopriate for seismic design. ln our opinion, the
developer should consider retaining a geophysicdl mnsultant to assist with evaluation of the
seismic site soil classification of the site. We consiider the seismic criteria on the table below to
be appropriate for use in structural design at the sfte-
Table I
Seismic GriGria
Ss 0.32
Sr 0.057
Sos 0.24
Sor 0.083
Snns 0.36
Srvrr 0.13
Tr 4
PGAruI 4,2
Vsro 260
Seismic Design
Category B
Belled Piers
We understand that the client anticipates ltnat two of the one-story, metal buildings
planned for the site will be subject to significant u$frfr forces. The client desires belled pier foun-
dations for these buildings to resist the uplift. Oursurbsurface information indicates that the soils
below the site are generally sandy clay soil that b nrnedium stiff to very stiff with some very soft
zones. Gravel and cobble soil is below the sandy dhy, but the elevation is not consistent. The
gravel/cobbles are deeper than 30 feet at some localions. Design and construction criteria for
belled piers are below.
Belled piers should be designed fora maximum allowable end bearing pressure
of 3,000 psf. Skin friction should be meglected.
ANDOVER MANAGEMENT GROUP
214 CENTER DRIVE
GTLIT PROJECT NO. GS06693.001-125
1
Page 2 of 3
ffi
2
3
4
Piers should be reinforced full-length. Reinforcement shouH extend into the
grade beams and foundation walls. Additional reinforcemerft may be required
depending on structural analysis.
The belling tool should be used immediately upon completfrorn of drilling the
straight-shaft portion of the pier. The belling tool should be ur$ed to its full capaci-
ty. Casing should be available on-site to prevent caving of soiils into pier holes.
Piers should be carefully cleaned prior to placing concrete. C;oncrete should be
on-site and placed in the pier holes immediately after the holls have been drilled,
cleaned and observed. We recommend concrete with a mimirnum slump in the
range of 5 to 7 inches to reduce possibility of voids in the bdflbd portion of the
pier.
lnstallation of drilled piers should be observed by a represerntative of CTLIT to
verify subsoils are as anticipated and to observe the contr#s installation
technique.
mes D
{
5.
We are available to discuss the contents of this letter. Please contacfi us if you have
questions or need additional information.
CTLITHOMPSON, tNC Reviewed by:
,C, rffiF-
Barbone,
Division Manager
ANDOVER MANAGEMENT GROUP
214 CENTER DRIVE
GTLIT PROJECT NO. GS06693.001-125
ncipal Engineer
ikelloss@ctlthompson.com
Page 3 of 3
,&
-,!: