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GEOTECHNICAL INVESTIGATION
PROPOSED STEEL BUILDING
1140 DEVEREUX ROAD
GLENWOOD SPRINGS, COLORADO
Prepared For:
COLORADO ENERGY SYSTEMS
274 Mountain Shadows Drive
Glenwood Springs, Colorado 81601
Attention: Ian Moritz
Project No. GS06230.000-125
April 23, 2018
TABLE OF CONTENTS
SCOPE 1
SUMMARY OF CONCLUSIONS 1
SITE CONDITIONS 2
PROPOSED CONSTRUCTION 2
SUBSURFACE CONDITIONS 2
SITE EARTHWORK 3
Structural Fill 4
Foundation Wall Backfill 4
FOUNDATION 5
Footings 5
SLAB -ON -GRADE 5
BELOW -GRADE CONSTRUCTION 6
SURFACE DRAINAGE 6
CONCRETE 7
GEOTECHNICAL RISK 8
LIMITATIONS 9
FIGURE 1 —VICINITY MAP
FIGURE 2 — LOCATIONS OF EXPLORATORY PITS
FIGURE 3 — SUMMARY LOGS OF EXPLORATORY PITS
FIGURE 4 — SWELL/CONSOLIDATION TEST RESULTS
FIGURE 5 — GRADATION TEST RESULTS
TABLE I — SUMMARY OF LABORATORY TESTING
COLORADO ENERGY SYSTEMS
PROPOSED STEEL BUILDING
PROJECT NO. GS06230.000-125
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SCOPE
This report presents the results of our geotechnical investigation for the pro-
posed steel building at 1140 Devereux Road in Glenwood Springs, Colorado. A
vicinity map with the location of the site is shown on Figure 1. We conducted this
investigation to evaluate subsurface conditions at the site and provide geotech-
nical engineering recommendations for the planned building. Our report was pre-
pared from data developed from our field exploration, laboratory testing, engineer-
ing analysis, and our experience with similar conditions. This report includes a de-
scription of the subsurface conditions observed in our exploratory pits and pre-
sents geotechnical engineering recommendations for design and construction of
foundations, floor slabs, and details influenced by the subsoils. A summary of our
conclusions is presented below.
SUMMARY OF CONCLUSIONS
1. Subsoils encountered in our exploratory pits consisted of about 2
feet of gravel fill or 6 inches of topsoil over 2 and 3.5 feet of natural
sandy clay underlain by clayey gravel with cobbles to the total ex-
plored depth of 6.5 feet. Groundwater was not found in our explora-
tory pits.
2. The building can be constructed on footing foundations supported by
the undisturbed, natural clayey gravel soil. If needed, densely -com-
pacted, granular structural fill can be placed to reattain footing eleva-
tions after removal of deleterious fill and clay soils. Design and con-
struction criteria for footing foundations are in the report.
3. The fill and natural clay soils possess poor support characteristics as
compare to the underlying, natural gravel soil. We recommend sub -
excavation of at least 2 feet of the soils below the floor slab and re-
placement with densely -compacted, granular structural fill.
4. Surface drainage should be designed to provide for rapid removal of
surface water away from the building.
COLORADO ENERGY SYSTEMS
PROPOSED STEEL BUILDING
PROJECT NO. GS06230.000-125
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1
SITE CONDITIONS
The site is located at 1140 Devereux Road in Glenwood Springs (see Fig-
ure 2). The Colorado River is beyond the road to the northeast. The lot is cur-
rently being used for equipment storage and is generally covered with a gravel
drive surface. Ground surface on the property is generally flat, sloping down to the
northeast at grades less than 5 percent.
PROPOSED CONSTRUCTION
The proposed building is a pre-engineered steel structure with a footprint of
about 80 feet by 40 feet. A slab -on -grade floor is planned. No below -grade areas
will be built. We expect maximum excavation depths of 3 to 4 feet to remove dele-
terious soils and construct foundations. Foundation loads along perimeter walls
will likely be less than 3,000 pounds per linear feet. Maximum interior column
loads are anticipated at 50 kips. If actual construction will vary from our descrip-
tion, we should be informed.
SUBSURFACE CONDITIONS
Subsurface conditions at the site were investigated by observing the exca-
vation of two exploratory pits at the approximate locations shown on Figure 2.
Subsurface conditions observed in the pits were logged by our field representative
who obtained samples of the soils. Subsoils found in our exploratory pits con-
sisted of about 2 feet of fill or 6 inches of topsoil over 2 and 5 feet of natural sandy
clay underlain by natural clayey gravel with cobbles to the total explored depth of
6.5 feet. Groundwater was not found in our pits at the time of excavation. The pits
COLORADO ENERGY SYSTEMS
PROPOSED STEEL BUILDING
PROJECT NO. G506230.000-125
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2
were backfilled after completion of our field investigation. Graphic logs of the soils
observed in the exploratory pits are shown on Figure 3.
Samples of the soils obtained in the field were returned to our laboratory for
classification testing and testing for pertinent engineering parameters. One sam-
ple of the clay selected for one-dimensional, swell -consolidation testing exhibited
low swell potential. Swell -consolidation test results are shown on Figure 4. Gra-
dation test results on samples of the natural gravel soil are shown on Figure 5.
Laboratory test results are summarized on Table I.
SITE EARTHWORK
We anticipate maximum excavation depths of about 4 feet to remove fill and
clay soils from below footing foundations. Excavations at the site can be accom-
plished with typical heavy-duty excavation equipment. Sides of excavations need
to be sloped to meet local, State, and federal safety regulations. The upper clay
soils will likely classify as a Type B soil based on OSHA criteria. The gravel soil
will classify as a Type C soil. Excavations should be sloped no steeper than 1 to 1
horizontal to vertical in Type B soils and 1.5 to 1 in Type C soils.
Free groundwater was not encountered in our exploratory pits during exca-
vation operations. We do not anticipate ground water will be encountered in exca-
vations for the proposed construction. We suggest excavations be sloped to a
gravity discharge or to a temporary sump where water from precipitation and run-
off can be removed by pumping.
COLORADO ENERGY SYSTEMS
PROPOSED STEEL BUILDING
PROJECT NO, GS06230.000-125
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Structural Fill
The existing fill and clay soils at this site are variable and possess poor sup-
port characteristics as compared to the underlying, natural gravel soil. To en-
hance potential performance of the floor slab, we recommend sub -excavation of at
least 2 feet of the soils below the slab and replacement with densely -compacted,
granular structural fill. Granular structural fill can also be placed to reattain footing
elevations after removal of deleterious fill and clay soils. We recommend that
structural fill below footings and slabs consist of an AASHTD Class 6 aggregate
base course or similar material.
Structural fill should be moisture -conditioned to within 2 percent of optimum
moisture content and placed in loose lifts of 10 inches thick or less. Structural fill
should be compacted to 98 percent of standard Proctor (ASTM D 698) maximum
dry density. Moisture content and density of structural fill should be checked by a
representative of our firm during placement. Observation of the compaction proce-
dure is necessary.
Foundation Wall Backfill
Proper placement and compaction of foundation backfill is important to re-
duce infiltration of surface water and settlement of backfill. The on-site soils can
be reused as backfill, provided they are free of rocks larger than 6 inches in diam-
eter, 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 mois-
ture content, and compacted to at least 95 percent of maximum standard Proctor
dry density (ASTM D 698). Moisture content and density of the backfill should be
checked during placement by a representative of our firm.
COLORADO ENERGY SYSTEMS
PROPOSED STEEL BUILDING
PROJECT NO. GS06230.000-125
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FOUNDATION
The building can be constructed on footing foundations supported by the
undisturbed, natural clayey gravel soil. If needed, densely -compacted, granular
structural fill can be placed to reattain footing elevations after removal of deleteri-
ous fill and clay soils. Structural fill should be in accordance with recommenda-
tions in the Structural Fill section. Recommendations for design and construction
of footings are below.
Footings
1. Footings placed on the undisturbed, natural gravel soil or densely -
compacted, granular structural fill can be sized using a maximum al-
lowable bearing pressure of 4,000 psf. Soils loosened during the ex-
cavation and forming process should be recompacted or removed
prior to placing concrete.
2. Continuous wall footings should have a minimum width of at least 16
inches. Column footings should have a minimum dimension of 24
inches. Larger sizes may be required, depending upon foundation
loads.
3. Grade beams and foundation walls should be well reinforced, top
and bottom, to span undisclosed loose or soft soil pockets. We rec-
ommend reinforcement sufficient to span an unsupported distance of
at least 12 feet.
4. The soils under exterior footings should be protected from freezing.
We recommend the bottom of footings be constructed at a depth of
at least 36 inches below finished exterior grades. The Glenwood
Springs building department should be consulted regarding required
depth.
SLAB -ON -GRADE
A slab -on -grade floor will be constructed in the building. The floor should
be constructed on a mat of structural fill. The existing fill and natural clay soils are
COLORADO ENERGY SYSTEMS
PROPOSED STEEL BUILDING
PROJECT NO. GS06230.000-125
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variable and possess poor support characteristics as compared to the underlying,
natural gravel soil. We recommend sub -excavation of at least 2 feet of the existing
fill and clay soils below the floor slab and replacement with densely -compacted,
granular structural fill. Recommendations in the Structural Fill section should be
followed.
Floor slabs should be separated from exterior walls and interior bearing
members with slip joints which allow free vertical movement of the slabs. Exterior
concrete flatwork should be isolated from the building. These slabs should be
well -reinforced to function as independent units. Frequent control joints should be
provided, in accordance with American Concrete Institute (ACI) recommendations,
to reduce problems associated with shrinkage and curling.
BELOW -GRADE CONSTRUCTION
We understand below -grade areas are not planned for the building. If con-
struction plans change to include a below -grade area, such as a basement, we
should be notified so that we can provide criteria for lateral earth pressures and
subsurface drainage.
SURFACE DRAINAGE
Surface drainage is critical to the performance of foundations, slabs and ex-
terior flatwork. We recommend the following precautions be observed during con-
struction and maintained at all times after the building is constructed:
1. The ground surface, including pavements, should be sloped to drain
away from the building in all directions. We recommend providing a
slope of at least 12 inches in the first 10 feet around the building,
COLORADO ENERGY SYSTEMS
PROPOSED STEEL BUILDING
PROJECT NO. GS06230.000-125
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where possible. Pavements adjacent to buildings should be sloped
to rapidly convey surface water away from building.
2. The building should be provided with roof gutters and downspouts.
Roof downspouts and drains should discharge well beyond the limits
of all backfill. Splash blocks and downspout extensions should be
provided at all discharge points.
3. Landscaping should be carefully designed to minimize irrigation.
Plants used near foundation walls should be limited to those with low
moisture requirements; irrigated grass should not be located within 5
feet of the foundation. Sprinklers should not discharge within 5 feet
of the foundation and should be directed away from the building.
CONCRETE
Concrete in contact with soil can be subject to sulfate attack. We measured
water-soluble sulfate concentrations in two samples from this site. Concentrations
were measured at 0.06 and 0.08 percent. For this level of sulfate concentration,
ACI 332-08 Code Requirements for Residential Concrete indicates there are no
special requirements for sulfate resistance.
In our experience, superficial damage may occur to the exposed surfaces of
highly permeable concrete, even though sulfate levels are relatively low. To control
this risk and to resist freeze -thaw deterioration, the water-to-cementitious materials
ratio should not exceed 0.50 for concrete in contact with soils that are likely to stay
moist due to surface drainage or high-water tables. Concrete should have a total
air content of 6% +/-1.5%. We recommend all foundation walls and grade beams
in contact with the subsoils (including the inside and outside faces of garage and
crawl space grade beams) be damp -proofed.
COLORADO ENERGY SYSTEMS
PROPOSED STEEL BUILDING
PROJECT NO. GS06230.000-125
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GEOTECHNICAL RISK
The concept of risk is an important aspect of any geotechnical evaluation.
The primary reason for this is that the analytical methods used to develop ge-
otechnical recommendations do not comprise an exact science. The analytical
tools which geotechnical engineers use are generally empirical and must be tem-
pered by engineering judgment and experience. Therefore, the solutions or rec-
ommendations presented in any geotechnical evaluation should not be considered
risk-free and, more importantly, are not a guarantee that the interaction between
the soils and that the proposed structure will perform as desired or intended. What
the engineering recommendations presented in the preceding sections do consti-
tute is our estimate, based on the information generated during this and previous
evaluations and our experience in working with these conditions, of those
measures that are necessary to help the building perform satisfactorily.
This report has been prepared for the exclusive use of the client for the pur-
pose of providing geotechnical design and construction criteria for the proposed
project. The information, conclusions, and recommendations presented herein are
based upon consideration of many factors including, but not limited to, the type of
structure proposed, the geologic setting, and the subsurface conditions encoun-
tered. The conclusions and recommendations contained in the report are not valid
for use by others. Standards of practice continuously change in the area of ge-
otechnical engineering. The recommendations provided in this report are appro-
priate for three years. If the proposed project is not constructed within three years,
we should be contacted to determine if we should update this report.
COLORADO ENERGY SYSTEMS
PROPOSED STEEL BUILDING
PROJECT NO. GS06230.000-125
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LIMITATIONS
Our exploratory pits were located to provide a reasonably accurate picture
of subsurface conditions. Variations in the subsurface conditions not indicated by
the pit will occur.
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. If we can be of further service in discussing the contents of this re-
port, please call.
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Reviewed By:
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cc: Via email to ian(a�coloradoenergysystems.com
COLORADO ENERGY SYSTEMS
PROPOSED STEEL BUILDING
PROJECT NO. GS06230.000-125
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S06230.000_F1 04 061EMO
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SCALE: 1 ° = 500'
Colorado Energy Systems
Proposed Steel Building
Project No. GS06230.000-125
Vicinity
Map
Fig. 1
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LEGEND:
TP -1 APPROXIMATE LOCATION
• OF EXPLORATORY PIT.
Colorado Energy Systems
Proposed Steel Building
Project No. GS06230.000-125
Locations of
Exploratory
Pits
Fig. 2
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COLORADO ENERGY SYSTEMS
PROPOSED STEEL BUILDING
PROJECT N0. GS06230.000-120
15
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LEGEND:
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NOTES:
SANDY CLAY "TOPSOIL", ORGANICS,
MOIST, BROWN.
FILL, GRAVEL, COBBLES, DENSE, MOIST,
BROWN.
CLAY, SANDY, STIFF, MOIST, RUST. (CL)
GRAVEL, CLAYEY, COBBLES, DENSE TO
VERY DENSE, MOIST, BROWN, RUST. (GC)
INDICATES HAND DRIVE SAMPLE.
INDICATES BULK SAMPLE.
1. EXPLORATORY PITS WERE EXCAVATED
WITH A BACKHOE ON APRIL 6, 2018.
2. LOCATIONS OF EXPLORATORY PITS ARE
APPROXIMATE.
3. FREE GROUNDWATER WAS NOT FOUND IN
OUR EXPLORATORY PITS.
4. EXPLORATORY PITS ARE SUBJECT TO THE
EXPLANATIONS, LIMITATIONS AND
CONCLUSIONS CONTAINED IN THIS
REPORT.
Summary Logs of
Exploratory
Pits
FIG. 3
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EXPANSION UNDER CONSTANT
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0
10 100
APPLIED PRESSURE - KSF
Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT= 119 PCF
From TP -2 AT 2 FEET MOISTURE CONTENT= 6.4 %
COLORADO ENERGY SYSTEMS
PROPOSED STEEL BUILDING
PROJECT NO. GS06230.000-125
Swell Consolidation
Test Results
FIG. 4
Sample of GRAVEL, CLAYEY (GC)
From TP - 1 AT 4-6 FEET
GRAVEL 50 % SAND
32%
SILT & CLAY 18 % LIQUID LIMIT
PLASTICITY INDEX
HYDROMETER ANALYSIS I SIEVE ANALYSIS
25 FIR. 7 FIR. TIME READINGS U.S. STANDARD SERIES CLEAR SQUARE OPENINGS
45 MIN. 15 MIN. 60 MIN. 19 MIN. 4 MIN. 1 MIN. 200 100 50 '40 '30 96 *10 '8
100
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.001 0 002 .005 .009 .019 .037 .074 .149 .297 .590 1 19 2.0 2.38 4.76 9 52 19.1 36.1 76.2 127 200
0.42 152
DIAMETER OF PARTICLE IN MILLIMETERS
CLAY TO SILT
SANDS
GRAVEL
(PLASTIC) (NON -PLASTIC)
FINE I MEDIUM (COARSE
FINE I COARSE I COBBLES
Sample of GRAVEL, CLAYEY (GC)
From TP - 1 AT 4-6 FEET
GRAVEL 50 % SAND
32%
SILT & CLAY 18 % LIQUID LIMIT
PLASTICITY INDEX
Sample of GRAVEL, CLAYEY (GC)
From TP - 2 AT 4-6 FEET
COLORADO ENERGY SYSTEMS
PROPOSED STEEL BUILDING
PROJECT NO. GS06230.000-125
GRAVEL 59 % SAND 26 %
SILT & CLAY 15 % LIQUID LIMIT
PLASTICITY INDEX %
Gradation
Test Results
FIG. 5
HYDROMETER ANALYSIS I SIEVE ANALYSIS
25 FIR. 7 HR. TIME READINGS U.S STANDARD SERIES CLEAR SQUARE OPENINGS
45 MIN. 15 MIN. 60 MIN. 19 MIN. 4 MIN. 1 MIN. 200 900 50*40'30 *16 10 *8
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0.42 152
DIAMETER OF PARTICLE IN MILLIMETERS
CLAY TO SILT
SANDS
GRAVEL
(PLASTIC) (NON -PLASTIC)
FINE MEDIUM I COARS
FINE I COARSE I COBBLES
Sample of GRAVEL, CLAYEY (GC)
From TP - 2 AT 4-6 FEET
COLORADO ENERGY SYSTEMS
PROPOSED STEEL BUILDING
PROJECT NO. GS06230.000-125
GRAVEL 59 % SAND 26 %
SILT & CLAY 15 % LIQUID LIMIT
PLASTICITY INDEX %
Gradation
Test Results
FIG. 5
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