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GEOTECHNICAL ENGINEERING
RECOMMENDATIONS
MONTEZUMA COUNTY COMBINED COURT SYSTEMS
BUILDING
Cortez, Colorado
Prepared For:
Ms. Melissa Brunner, Montezuma County
Project Number: 54077GE
January 28, 2016
PN: 54077GE
January 28, 2016
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1.0 REPORT INTRODUCTION ................................................................................................ 2
1.1 Scope of Project ................................................................................................................... 3
2.0 GEOTECHNICAL ENGINIEERING STUDY .................................................................. 3
2.1 Geotechnical Engineering Study Scope of Service .............................................................. 3
3.0 FIELD STUDY ....................................................................................................................... 5
3.1 Project location .................................................................................................................... 5
3.2 Site Description and Geomorphology .................................................................................. 6
3.3 Subsurface Soil and Water Conditions ................................................................................ 7
3.4 Anticipated Excavation Characteristics of the Formational Materials ................................ 9
3.5 Excavation Cut to Embankment Fill Shrink/Swell Factors ................................................ 10
3.6 Site Seismic Classification .................................................................................................. 11
4.0 LABORATORY STUDY .................................................................................................... 12
5.0 FOUNDATION RECOMMENDATIONS ........................................................................ 14
5.1 Spread Footings Supported by the Competent Formational Sandstone Material ............. 15
5.2 Spread Footings Supported by the Site Clay Soil Materials.............................................. 19
5.3 General Shallow Foundation Considerations ................................................................... 24
6.0 RETAINING STRUCTURES............................................................................................. 24
7.0 SUBSURFACE DRAIN SYSTEM ...................................................................................... 26
8.0 CONCRETE FLATWORK ................................................................................................. 28
8.1 Interior Concrete Slab-on-Grade Floors ............................................................................ 28
8.2 Exterior Concrete Flatwork Considerations ...................................................................... 30
8.3 General Concrete Flatwork Comments ............................................................................. 31
9.0 PAVEMENT SECTION THICKNESS DESIGN RECOMMENDATIONS .................. 32
9.1 Asphalt Pavement Recommendations ................................................................................. 33
9.2 Rigid Concrete Pavement Recommendations ..................................................................... 34
9.3 General Parking Area Considerations ................................................................................. 35
10.0 CONSTRUCTION CONSIDERATIONS ........................................................................ 36
10.1 Fill Placement Recommendations ..................................................................................... 36
10.1.1 Natural Soil Fill ........................................................................................................ 36
10.1.2 Granular Compacted Structural Fill ......................................................................... 37
10.2 Excavation Considerations ............................................................................................... 38
10.2.1 Excavation Cut Slopes ............................................................................................... 39
10.3 Utility Considerations ....................................................................................................... 39
10.4 Exterior Grading and Drainage Comments ..................................................................... 40
10.5 Landscaping Considerations ............................................................................................ 40
10.6 Soil Sulfate Content, Corrosion Issues ............................................................................. 42
10.7 Radon Issues ..................................................................................................................... 42
11.0 CONSTRUCTION MONITORING AND TESTING .................................................... 42
12.0 CONCLUSIONS AND CONSIDERATIONS ................................................................. 43
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January 28, 2016
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1.0 REPORT INTRODUCTION
This report presents our geotechnical engineering recommendations for the Montezuma County
Combined Court System Project. This report was requested by Melissa Brunner, Montezuma
County Administrator. The field study was performed on January 7 through January 20, 2016.
The laboratory study was completed on January 25, 2016. We provided verbal recommendations
and consultation to members of the design team during the preparation of this report.
Geotechnical engineering is a discipline which provides insight into natural conditions and site
characteristics such as; subsurface soil and water conditions, soil strength, swell (expansion)
potential, consolidation (settlement) potential, and often slope stability considerations. Typically
the information provided by the geotechnical engineer is utilized by many people including the
project owner, architect or designer, structural engineer, civil engineer, the project builder and
others. The information is used to help develop a design and subsequently implement
construction strategies that are appropriate for the subsurface soil and water conditions. It is
important that the geotechnical engineer be consulted throughout the design and construction
process to verify the implementation of the geotechnical engineering recommendations provided
in this report. Generally the recommendations and technical aspects of this report are intended
for design and construction personnel who are familiar construction concepts and techniques, and
understand the terminology presented below. We should be contacted if any questions or
comments arise as a result of the information presented below.
The following outline provides a synopsis of the various portions of this report;
� Sections 1.0 and 2.0 provide an introduction and an establishment of our scope of
service.
� Sections 3.0 and 4.0 of this report present our geotechnical engineering field and
laboratory studies
� Sections 5.0 through 9.0 presents our geotechnical engineering design parameters and
recommendations which are based on our engineering analysis of the data obtained.
� Section 10.0 provides a brief discussion of construction sequencing and strategies which
may influence the geotechnical engineering characteristics of the site.
The discussion and construction recommendations presented in Section 10.0 are intended to
help develop site soil conditions that are consistent with the geotechnical engineering
recommendations presented previously in the report. Ancillary information such as some
background information regarding soil corrosion and radon considerations is presented as
general reference. The construction considerations section is not intended to address all of the
construction planning and needs for the project site, but is intended to provide an overview to
aid the owner, design team, and contractor in understanding some construction concepts that
may influence some of the geotechnical engineering aspects of the site and proposed
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development.
The data used to generate our recommendations are presented throughout this report and in the
attached figures.
1.1 Scope of Project
We understand that the proposed project will consist of constructing a pre-engineered metal-
framed building that is supported by a steel reinforced concrete foundation system. A partial
basement with a mechanical room and “sally port” will be constructed under the northern portion
of the building. A combination of concrete slab-on-grade and structurally supported floors (at
minimum over basement areas) will be used for the interior building floor system. The
development will include asphalt pavement driveway and parking areas as well as exterior
concrete flatwork.
2.0 GEOTECHNICAL ENGINIEERING STUDY
This section of the report presents our geotechnical engineer scope of services to date for the
project.
Our services include a geotechnical engineering study of the subsurface soil and water
conditions of this site for development of a foundation design and pavement section thickness
study for the proposed use.
2.1 Geotechnical Engineering Study Scope of Service
The scope of our study which was delineated in our proposal for services, and the order of
presentation of the information within this report, is outlined below.
Field Study
• We advanced eighteen (18) continuous flight auger test borings and two (2) NW wireline
core borings at the project within the areas we understand are planned for construction of
the proposed structure and parking/landscape areas.
• Select driven sleeve and bulk soil samples were obtained from the test borings and
returned to our laboratory for testing.
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Laboratory Study
• The laboratory testing and analysis of the samples obtained included;
� Moisture content and dry density,
� Direct shear strength tests, to help establish a basis for development of soil
bearing capacity and lateral earth pressure values,
� Unconfined compressive strength tests on select sections of rock core obtained
from our wireline core borings,
� Swell/consolidation tests to help assess the expansion and consolidation potential
of the support soils on this site to help estimate potential uplift associated with
expansive soils and to help estimate settlement of the foundation system,
� Plastic and liquid limit tests to determine the Plasticity Index of the soil,
� Sieve analysis tests,
� Moisture content/dry density relationship (Proctor) tests, and,
� California Bearing Ratio (CBR) tests.
Geotechnical Engineering Recommendations
• This report addresses the geotechnical engineering aspects of the site and provides
recommendations including;
Geotechnical Engineering Section(s)
� Subsurface soil and water conditions that may influence the project design
and construction considerations,
� Geotechnical engineering design parameters including;
� Viable foundation system concepts including soil bearing capacity
values,
� settlement considerations for the foundation system concepts that are
viable for this project,
� Lateral Earth Pressure values for design of retaining structures, and,
� Flexible asphalt concrete pavement thickness design considerations
� Soil support considerations for interior and exterior concrete flatwork
Construction Consideration Section
� Fill placement considerations including cursory comments regarding site
preparation and grubbing operations,
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� Considerations for excavation cut slopes,
� Natural soil preparation considerations for use as backfill on the site,
� Compaction recommendations for various types of backfill proposed at the
site,
� Utility trench comments, and,
� Cursory exterior grading considerations
• This report provides design parameters, but does not provide foundation design or
design of structure components. The project architect, designer, structural engineer or
builder may be contacted to provide a design based on the information presented in
this report.
• Our subsurface exploration, laboratory study and engineering analysis do not address
environmental or geologic hazard issues other than expansive soil conditions.
3.0 FIELD STUDY
3.1 Project location
The project site is located west of the intersection of North Park Street and East Driscoll Street,
just south of the existing Montezuma County Detention Center. Figure 3.1 shown below
obtained from Google Earth imagery indicates the location of the project site.
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Figure 3.1: Project Location
3.2 Site Description and Geomorphology
The project site is located on a previously undeveloped approximate 6.8 acre lot. The project
site is relatively barren with vegetation consisting of sparse sage brush and grass cover. The
ground surface on the project site generally slopes down to the north with slope inclinations in
the range of about fifteen to one (15:1, horizontal to vertical) or flatter. A relatively shallow
drainage feature with a gradient down to the north towards Park Street exists in the north central
portion of the lot.
The geomorphology in the vicinity of the project consists of a relatively shallow wind-blown
loess deposit consisting of fine sands and clay and silt soil materials overlying the Dakota
Sandstone Formation. The clay soil materials encountered in the vicinity of the project may
exhibit a moderate to high swell potential and moderate consolidation potential under typical
foundation loads. The Dakota Sandstone Formation consists of interbedded layers of sandstone,
claystone, and shale materials. Lignite (coal like material) is sometimes encountered within the
formational material. The claystone and shale materials encountered within the formational
material may exhibit a moderate to high swell potential.
Project Location
N
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January 28, 2016
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Subsurface water is often encountered in the vicinity of the project. We suspect that the source
for this subsurface water is the relatively heavily irrigated park system and related canal systems
located to the southeast of the subject project site. Water may be encountered over the
formational sandstone material or within fractures within the formational materials.
3.3 Subsurface Soil and Water Conditions
We advanced eighteen (18) continuous flight auger test borings and two (2) NW wireline core
borings in the vicinity of the proposed structure and proposed parking/landscape areas. The
surveyed location of our test borings relatively to the approximate location of the structure are
shown on Figure 3.3 below. The surveying and development of the figure below was provided to
us by Maness and Associates. The logs of the soils encountered in our test borings are presented
in Appendix A.
Figure 3.3: Test Boring Locations
N
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January 28, 2016
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The test boring locations were survey located however the location of the structure footprint
relatively to our test borings has been approximated. We understand that the building location
relative to our test boring locations should be accurate to within a few feet.
The following provides a general description of the subsurface conditions that we encountered
in our test borings. The logs of the test borings presented in Appendix A should be consulted for
more precise information.
Generally, we encountered sandy clay soil material from the ground surface to depths ranging
from about one and one-half (1½) to as deep as about eight (8) feet below the ground surface
where we encountered the Dakota Sandstone Formation. The upper approximate one (1) foot of
sandy clay soil materials were generally very moist and soft, becoming stiffer and drier with
depth. The clay soil materials encountered and tested exhibit a low to moderate swell potential,
and moderate to high consolidation potential.
The formational material was encountered at depths ranging from about one and one-half (1½)
to about eight (8) feet below the ground surface elevation. The upper portion of the formational
material was very hard. All of our auger test borings, with exception to Test Borings Four
through Seven, were advanced to refusal within about one-half (1/2) to one (1) foot of
penetration into the formational material. We were able to advance auger Test Borings Four
through Seven through the upper very hard sandstone material into more friable sandstone
material and claystone materials. The claystone materials were encountered at depths ranging
from about ten (10) to fifteen (15) feet below the ground surface. Test Borings Four through
Seven were advanced to refusal on a deeper very hard sandstone layer encountered at depths
ranging from about eighteen (18) to as deep as about thirty-eight (38) feet below the ground
surface elevation.
We advanced two (2) NW wireline core borings in the vicinity of the project (eastern area of the
proposed structure location) where we encountered shallow auger drilling refusal. We have
referred to these core borings as TB-2A and TB-10A. In TB-2A we encountered sandy clay soil
material from the ground surface to a depth of about two (2) feet below the ground surface
elevation where we encountered very hard sandstone formational material. The formational
material encountered consisted of very hard and moderately fractured sandstone to a depth of
about seven (7) feet below the ground surface. At depths ranging from about seven (7) to twelve
(12) feet below the ground surface we encountered highly fractured and more friable sandstone
material. We encountered highly fractured clayey sandstone to sandy claystone at depths ranging
from about twelve (12) feet below the ground surface to a depth of about twenty (20) feet below
the ground surface where primarily sandstone material was encountered. TB-2A was advanced
to a depth of about twenty-two (22) feet below the ground surface elevation.
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In TB-10A we encountered sandy clay soil materials from the ground surface to a depth of
approximately five (5) feet below the ground surface where we encountered hard claystone
material to a depth of about seven (7) feet below the ground surface. Very hard and moderately
fractured sandstone material was encountered at a depth of about seven (7) feet below the ground
surface elevation to the bottom of the core boring advanced to twelve (12) feet below the ground
surface elevation.
Subsurface free water was initially encountered at a depth of about twenty-five (25) feet below
the ground surface elevation in Test Boring Four. Subsequent measurements of the free water
elevation in Test Boring Four were at about twenty-one (21) feet below the ground surface. We
measured subsurface free water at a depth of about sixteen (16) feet below the ground surface
elevation in Test Boring/Core 2A. The free water was encountered in fractures within the
formational materials. We anticipate that the source area for this free water is from the heavily
irrigated park system and associated canals located a relatively short distance to the southeast of
the project site. Based on the subsurface information obtained we anticipate that the proposed
structure will be located above the static water elevation for the area. However we anticipate that
a periodic or seasonal water surface may develop over the formational sandstone material or
within fractures in the upper portions of the formational sandstone materials within the extent of
the structure depth during periods of high precipitation or spring snow melt. This is due to the
relatively shallow depth and impermeable nature of the formational sandstone material below
and adjacent to the project site. Our recommendations for a subsurface drain system may be
found in Section 7.0 of this report.
The logs of the subsurface soil conditions encountered in our test borings are presented in
Appendix A. The logs present our interpretation of the subsurface conditions encountered
exposed in the test borings at the time of our field work. Subsurface soil and water conditions
are often variable across relatively short distances. It is likely that variable subsurface soil and
water conditions will be encountered during construction. Laboratory soil classifications of
samples obtained may differ from field classifications.
3.4 Anticipated Excavation Characteristics of the Formational Materials
Based on our understanding of the proposed structure finished floor elevations we anticipate
that at minimum the entire basement area foundation system will be located within the
formational sandstone materials. The main level foundation system may be slightly below the
formational sandstone materials in some areas of the structure footprint.
As discussed above, the upper portions of the formational sandstone material were very hard.
We experienced auger refusal with our four (4) inch diameter solid stem auger utilizing our
approximate 12,000 pound CME-45 drilling equipment in many areas of the structure footprint
and proposed exterior landscape areas. Due to the auger refusal experienced during our initial
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field study we advanced additional NW wireline core borings in select locations of the structure
area (TB-2A and TB-10A). The upper approximate five (5) to six (6) feet of the formational
materials encountered exhibited Rock Quality Designation (RQD) values in the range of about
60% to 85%, meaning relatively competent sandstone with moderate to low fracturing. We
performed unconfined compressive strength testing of select sections of rock core obtained from
the upper portions of the formational sandstone material. The compressive strength of the rock
core tested ranged from about 4,500 pounds per square inch (psi) to over 10,000 psi. The
formational materials encountered below the upper approximate five (5) to six (6) feet of the
surface of the formation were considerably more fractured and friable with a compressive
strength in the range of about 1,000 psi.
Based on our understanding of the structure finished floor and basement floor elevations, the
structure basement foundation system will be located within the very hard sandstone materials
that exhibited moderate to low fracturing with compressive strengths ranging from about 4,500
psi to over 10,000 psi. We anticipate that blasting will be necessary to efficiently remove the
very hard sandstone formational materials in some areas of the project. Blasting must be
performed very carefully by an experienced blaster to ensure that the foundation bearing
materials are not compromised for support of the structure. Careful attention must be given to
post blasting operations to insure that the foundation support materials have not been
compromised or portions of the formational materials located behind the proposed basement
retaining walls have not been destabilized. We are available to assist with these post blasting
observations. Where possible, we recommend that alternative excavation methods be used to
more precisely excavate the foundation bearing support elevation with less potential for
disturbance to the foundation support materials.
3.5 Excavation Cut to Embankment Fill Shrink/Swell Factors
We understand that excavation cut and embankment fill construction will be used to establish
the project site grade(s). This section of the report provides estimated shrink/swell factors for
excavated material that will be placed and compacted as embankment fill. The factors provided
are applicable for the sandy clay soil materials located above the formational sandstone materials.
All embankment fill placed on the project site should be compacted to at least ninety (90)
percent of the Modified Proctor (ASTM D1557). The factor provided below is based on an
average value of the existing in-place density for the native sandy clay soil materials compacted
to ninety (90) percent of the Modified Proctor (ASTM D1557).
We obtained a number of driven Modified California Barrel liners within the native sandy clay
soil materials; however the number of samples that could be obtained was limited due to the
relatively shallow depth of the formational material underlying the project site. The dry density
and moisture content of these liner samples are tabulated in Section 4.0 below. An average dry
density of about 117 pounds per cubic foot was obtained for the liner samples obtained and tested
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from the sandy clay soil materials that overlie the formational sandstone material.
The results of the Modified Proctor test are presented in Section 4.0 below. We obtained a
maximum dry density of about 124 pounds per cubic foot at an optimum moisture content of
about 11.0 percent. Based on ninety (90) percent compaction, embankment fill material should
be compacted to about 112 pounds per cubic foot. Therefore we anticipate that it will require
between about 0.96 cubic yards of excavation cut within the site sandy clay soil materials to
produce about 1.0 cubic yard of embankment fill material. Therefore the swell factor from
excavation cut to embankment fill appears to be in the range of about 1.04. This value is not
applicable for the formational materials. We estimate a swell factor of about 1.2 from excavation
cut to embankment fill for the competent formational sandstone materials.
3.6 Site Seismic Classification
The seismic site class as defined by the 2009 International Building Code is based on some
average values of select soil characteristics such as shear wave velocity, standard penetration test
result values, undrained shear strength, and plasticity index.
Based on our standard penetration field tests and laboratory test results we feel that the
subsurface conditions for the project are consistent with the criteria for a Site Class C designation
as outlined in the 2009 International Building Code, Table 1613.5.2.
The table below presents seismic site coefficients for the project site based on a Site Class C
designation in conjunction with the mapped short period acceleration and long period
acceleration. The spectral response maps and subsequent seismic site coefficients were obtained
from the 2009 International Building Code Specifications.
Mapped Spectral
Short Period
Acceleration Ss
(Figure 1613.5(1))
Mapped Spectral
1-second
Acceleration S1
(Figure 1613.5(2))
Short Term Period Site
Coefficient Fa
(Table 1613.5.3 (1))
Long Term Period Site
Coefficient Fv
(Table 1613.5.3 (2))
0.20g
0.06g
1.2
1.7
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4.0 LABORATORY STUDY
The laboratory study included tests to estimate the strength, swell and consolidation potential of
the soils tested. We performed the following tests on select samples obtained from the test
borings.
Moisture content and dry density; the moisture content and in-situ dry density of some of the
soil samples were assessed in general accordance with ASTM D2216. The results of the
moisture content and dry density tests performed are tabulated below.
Sample Identification
and Depth
Sample Wet Density
(pcf)
Sample Moisture
Content (%)
Sample Dry Density
(PCF)
TB-3: 1.5 feet 109.8 3.3 106.3
TB-4: 13.5 feet 138.4 7.6 128.6
TB-5: 2 feet 116.4 4.8 111.1
TB-6: 4.5 feet 115.3 3.6 111.3
TB-8: 3.5 feet 118.3 2.5 115.4
TB-11: 1 foot 127.3 7.9 118.0
Atterberg Limits and Sieve Analysis; the plastic limit, liquid limit and plasticity index of some
of the soil samples was determined in general accordance with ASTM D4318. In conjunction
with the Atterberg Limits tests, sieve analysis tests were performed in general accordance with
ASTM D422 and D1140. The results of the sieve analysis and Atterberg Limits testing
performed are provided in Appendix B, Figures 4.1 through 4.6. The sandy clay soil materials
encountered and tested classify as USCS type “CL” or AASHTO type “A-6” sandy lean clay
material. The Plasticity Index of the clay soils tested range from about 9 to 16.
One Dimensional Swell-Consolidation Tests; the one dimensional swell-consolidation potential
of some of the soil samples obtained was determined. The soil sample tested is exposed to
varying loads and the addition of water. The one-dimensional swell-consolidation response of
the soil sample to the loads and/or water is represented graphically in Appendix B, Figures 4.7
through 4.12. The basic information obtained from the swell-consolidation tests performed is
tabulated below. We performed a swell pressure/ swell potential only for the test performed on
TB-2A at a sample depth of seventeen (17) feet therefore the swell/consolidation graph was not
produced for this sample. The results of the swell pressure/potential for this test are provided
below.
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Sample
Designation
Initial
Moisture
Content
Initial Dry
Density
(pcf)
Swell
Pressure
(psf)
Swell Potential
(percent)
TB-2A: 17 feet (claystone)
11.1% 127.4
(remold) 0 --
(100 psf surcharge load)
TB-3: 1.5 feet (sandy clay)
3.3% 106.3 0 -- (100 psf surcharge load)
TB-4: 13.5 feet (claystone)
7.6% 128.6 900 1.0% (100 psf surcharge load)
TB-5: 2 feet (sandy clay)
4.8% 111.1 0 --
(100 psf surcharge load)
TB-6: 4.5 feet (sandy clay)
3.6% 111.3 290 0.3%
(100 psf surcharge load)
TB-8: 3.5 feet (clayey sandstone)
2.5% 115.4 300 0.2%
(100 psf surcharge load)
TB-11: 1 foot (sandy clay)
7.9% 118.0 950 0.9%
(100 psf surcharge load)
Based on our laboratory test data the site clay soil materials and claystone materials encountered
within the formational materials exhibit a low to moderate swell potential. The sandy clay soil
materials encountered and tested that overlie the formational materials exhibited a moderate to
relatively high consolidation potential when exposed to typical spread footing foundation
pressures.
Unconfined Compressive Strength; the unconfined compressive strength of select sections of
the NWL (NQ diameter) core were tested for strength in our concrete press. The results of the
unconfined compressive strength tests are presented below.
NQ Core Boring and Depth
(feet below the ground surface)
Unit Weight
(pcf)
Ultimate Compressive Strength
(psi)
TB-2A at 2.5 feet
TB-2A at 10.0 feet
156.8
144.0
4,650
1,180
TB-10A @ 9.0 feet 157.4 10,520
Rock Quality Determination (RQD); The relative quality with regard to degree of fracturing of
the core was determined. The results of the RQD tests may be found on the NWL core logs
presented in Appendix A. The formational materials encountered in our core borings may be
generally considered as being moderately to highly fractured.
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Direct Shear Strength tests; direct shear strength tests were performed on select soil samples to
estimate the soil strength characteristics in general accordance with ASTM D3080. Based on the
test results, we used an angle of internal friction of thirty (30) degrees and cohesion of about 50
pounds per square foot for the sandy clay soil materials encountered in the upper soil strata. The
results of the direct shear strength test are shown on Figure 4.13.
Moisture content-dry density relationship (Proctor) tests; We performed laboratory moisture
content-dry density tests to assess the relationship between the soil moisture content and dry
density. The Proctor tests were performed in general accordance with ASTM D1557. We
obtained a maximum dry density of about 124.0 pounds per cubic foot at an optimum moisture
content of about 11.0% for the sandy clay soil materials encountered at the project site. The
results of the laboratory Proctor tests are presented on Figures 4.14.
California Bearing Ratio (CBR) Tests; We assessed the pavement section support
characteristics of select composite soil samples in general accordance with ASTM D1883. We
obtained a CBR value of about six (6) for the sandy clay subgrade soil materials compacted to
about ninety (90) percent of the maximum dry density as defined by the Modified Proctor test
(ASTM D1557). The results of the CBR tests are presented on Figure 4.15.
5.0 FOUNDATION RECOMMENDATIONS
Based on the subsurface conditions encountered and laboratory test data obtained, we feel that
the proposed structure may be supported by a conventional spread footing foundation system. As
discussed above, based on the data available to us at the time this report was prepared, the entire
basement/sally port corridor areas will extend into the competent formational materials. The
structure perimeter foundation system will be located on or within about two (2) feet of the
formational sandstone material for a “typical depth” bottom of footing elevation around the
southwest and majority of the southeast sides of the structure. However we anticipate that the
formational materials will be located more than two (2) feet to possibly as much as about six (6)
feet below a “typical depth” bottom of footing elevation for the northeastern area of the structure.
Section 5.1 below provides bearing capacity values and construction considerations for
extending the entire structure foundation system to bear on a layer of structural fill and/or lean
concrete fill that extends to the competent formational sandstone material. This footing support
strategy limits the potential for post construction differential settlement to occur in the
foundation system. The competent formational sandstone materials will provide a relatively
high bearing capacity value with minimal potential for post construction settlement or heave due
to expansive soil conditions. We calculated that the potential differential settlement between
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portions of the foundation system supported on the formational sandstone material versus
portions of the foundation system supported on the site clay soil materials that overlie the
formational material could be in the range of one (1) inch or greater. Therefore we do not
recommend that the structure foundation system bear on the different material types.
Section 5.2 provides bearing capacity values for supporting spread footings on the site sandy
clay soil materials. These recommendations are applicable for ancillary structures (that are not
structurally connected to the main structure) such as exterior retaining wall structures.
We are available to provide alternative foundation recommendations such as drilled caissons at
your request, however we do not feel that the use of a drilled caisson foundation system is
necessary based on the subsurface conditions encountered and laboratory test data.
The integrity and long-term performance of any foundation system is influenced by the quality
of workmanship which is implemented during construction. It is imperative that all excavation
and fill placement operations be conducted by qualified personnel using appropriate equipment
and techniques to provide suitable support conditions for the foundation system.
5.1 Spread Footings Supported by the Competent Formational Sandstone Material
The sketch provided below is intended to provide insight regarding the depth of the competent
formational sandstone material below the various areas of the structure layout. This figure is
based on the approximate location of our test borings relative to the proposed building footprint
as provided to us by Maness and Associates, the existing topography of the ground surface
around the structure area, and our understanding of the various finished floor elevations of the
structure. The actual depth of the formational sandstone material below the chosen footing
support elevation will likely vary somewhat from the approximate depths shown below. The
figure below is based on the following assumptions;
• The finished floor elevation of the main structure floor system will be at an elevation of
about 6164.5 feet. We have assumed a bottom of footing depth for the structure
perimeter footings of about 6160.5 feet. This portion of the foundation system is outlined
in the colors yellow and red in the sketch shown below.
• The finished floor elevation of the basement mechanical/electrical rooms and basement
corridor “sally port” will be at an elevation of about 6149.5 feet. We have assumed a
bottom of footing elevation for the structure basement/corridor walls of about 6148.5 feet.
This portion of the foundation system is outlined in green in the sketch below.
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The general foundation preparation strategy provided below should be followed for supporting
the entire structure foundation system on the competent formational sandstone materials.
N
Foundation system
located within competent
formational sandstone
materials
Foundation system
located near or about
two (2) feet above
competent formational
sandstone
Foundation system
located about two (2)
to as deep as about six
(6) feet above
competent formational
sandstone
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• The footing excavation should extend to the competent formational sandstone material.
Loose debris from the excavation (or blasting) operations must be removed to expose
competent formational sandstone material.
• We recommend a minimum structural fill depth of eight (8) inches be placed to help
achieve a uniform footing support elevation and to aid in the construction of concrete
formwork.
• For areas of the structure where the chosen footing support elevation is located within
about two and one-half (2½) feet of the competent formational material, an imported
structural fill may be placed and compacted to establish the bottom of footing elevation.
• For areas where the competent formation sandstone material is located between about two
and one-half (2½) feet or more below the chosen bottom of footing elevation we
recommend that a lean concrete fill be used to backfill the bottom of the footing
excavation to within about two (2) to two and one-half (2½) feet of the bottom of footing
elevation. An imported structural fill material may then be placed and compacted to
establish the bottom of footing elevation. The lean concrete fill material must be
adequately cured prior to placement of the compacted structural fill material.
• The structural fill material should be compacted to at least ninety (90) percent of the
maximum dry density as defined by ASTM D1557, Modified Proctor. In general we
recommend that the structural fill material consist of Colorado Department of
Transportation (CDOT) Class 6 material. Other types of structural fill material may
suitable as well. We are available to assess other material types for use as structural fill
material as the project progresses.
• The lean concrete fill material should consist of a minimum two (2) sack Portland
cement mix. A maximum lift thickness of about three (3) feet should be placed and
allowed to cure prior to placement of additional lifts of lean concrete fill. A higher
strength lean concrete fill such as a three (3) to four (4) sack mix may be used if it is
desired to speed up the strength gain curing process and/or if cold ambient air conditions
are present that would hamper the curing of lighter mixes.
• The lean concrete fill material may be placed neat within the foundation trench
excavation. The width of the lean concrete fill trench excavation should be equal to the
width of the structural fill material. The figure provided below indicates the necessary
width of structural fill material below the footing.
• Alternatively, if it is acceptable by the project structural engineer, the foundation system
may be stepped to limit the depth of fill materials under the footings.
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The compacted structural fill should be placed and compacted as discussed in the Construction
Considerations, “Fill Placement Recommendations” section of this report, below. The zone of
influence of the footing (at elevations close to the bottom of the footing) is often approximated as
being between two (2) lines subtended at 45 degree angles from each bottom corner of the
footing. The compacted structural fill should extend beyond the zone of influence of the footing
as shown in the sketch below.
A general and simple rule to apply to the geometry of the compacted structural fill blanket is
that it should extend beyond each edge of the footing a distance which is equal to the fill
thickness.
Spread footings and isolated footings may be designed using an allowable gross bearing
capacity of 4,500 pounds per square foot. The allowable gross bearing capacity may be increased
by twenty (20) percent due to transient loads. A coefficient of friction of 0.45 (based on
structural fill characteristics) may be used for lateral sliding calculations.
All footings should have a minimum depth of embedment of at least one (1) foot. The
embedment concept is shown below.
45 degrees 45 degrees
Footing
No Scale
Footing Zone of Influence Concept
Footing Zone of Influence
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We estimate that the footings designed and constructed as discussed above will have a total post
construction settlement of less than one-half (1/2) inch. Differential settlement between various
portions of the foundation system will be less than one-half (1/2) inch.
All footings should be support at an elevation deeper than the maximum depth of frost
penetration for the area. This recommendation includes exterior isolated footings and column
supports. We understand that the code frost depth for the City of Cortez is thirty-two (32) inches.
5.2 Spread Footings Supported by the Site Clay Soil Materials
This section of the report provides bearing capacity values for the site sandy clay soil materials
that overlie the formational materials. These recommendations are applicable for ancillary
structures such as exterior retaining wall footings that are not structurally attached to the main
structure.
The sandy clay soil materials encountered and tested exhibit swell pressures in the range of
about 300 to up to 900 pounds per square foot with a magnitude of swell potential up to about
one (1) percent when exposed to a 100 pound per square foot surcharge load. The site clay soil
materials encountered may be considered as having a low to perhaps moderate swell potential.
The samples tested exhibit a moderate to relatively high consolidation potential when exposed to
typical spread footing foundation pressures.
Minimum depth
of embedment Footing
Footing Embedment Concept
No Scale
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Properly designed and constructed continuous spread footings with stem walls/retaining walls
(beams) have the ability to distribute the forces associated with movement in the support soils.
The rigidity of the system helps reduce differential movement and associated damage to the
structure. Movement within the soils supporting isolated pad footings will result in direct
movement of the supported component. Damage to the structure due to this type of movement
can be severe. If possible, we recommend that isolated pad footings structurally connected to
other foundation elements be avoided and that the foundation system be designed as rigid as is
reasonably possible.
Careful preparation of the support soils, placement of granular compacted structural fill, careful
placement and compaction of stem wall backfill and positive surface drainage adjacent to the
foundation system all help reduce the influence of movement within the foundation support soils
on the performance of the spread footing foundation system.
We recommend that the footings be supported by a layer of moisture conditioned and
compacted natural soil which is overlain by a layer of compacted structural fill material. This
concept is outlined below;
• The foundation excavation should be excavated to at least one (1) foot below the
proposed footing support elevation.
• The natural soils exposed in the bottom of the excavation should be scarified to a depth of
about six (6) to eight (8) inches
• The scarified soil should be thoroughly moisture conditioned to about two (2) percent
above the laboratory determined optimum moisture content and then compacted.
• After completion of the compaction of the moisture conditioned natural soil a one (1) foot
thick layer of granular aggregate base course structural fill material should be placed,
moisture conditioned and compacted.
• The moisture conditioned natural soil material and the granular soils should be compacted
as discussed under the Compaction Recommendations portion of this report, below.
All footings should have a minimum depth of embedment of at least one (1) foot. Exterior
footings should have a minimum depth of embedment at least equal to the code frost depth. The
embedment concept is shown below.
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Spread footings located away from sloped areas may be designed using the allowable gross
bearing capacity values tabulated below.
Minimum Depth of
Embedment (Feet)
Continuous Footing Design
Capacity (psf)
Isolated Footing Design
Capacity (psf)
1 1,500 2,000
2 2,000 2,500
3 2,500 3,000
The bearing capacity values tabulated above may be increased by twenty (20) percent for
transient conditions associated with wind and seismic loads. Snow loads are not transient loads.
The bearing capacity values above are based on a continuous spread footing width in the range
of about two (2) to three (3) feet and an isolated footing width in the range of about three (3) to
four (4) feet. Larger footings and/or footings placed on deeper depth of compacted structural fill
will have a higher design soil bearing capacity. Development of the final footing design width is
usually an iterative process based on evaluation of design pressures, footing widths and the
thickness of compacted structural fill beneath the footings. We should be contacted as the design
process continues to re-evaluate the design capacities above based on the actual proposed footing
geometry.
Minimum depth
of embedment Footing
Footing Embedment Concept
No Scale
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The settlement of the spread footing foundation system will be influenced by the footing size
and the imposed loads. We estimated the total post construction settlement of the footings based
on our laboratory consolidation data, the type and size of the footing. Our analysis below
assumed that the highest bearing capacity value tabulated above was used in the design of the
footings. The amount of post construction settlement may be reduced by placing the footings on
a blanket of compacted structural fill material.
The estimated settlement for continuous footing with a nominal width of about two (2) to three
(3) feet are tabulated below
Thickness of Compacted
Structural Fill (feet)
Estimated Settlement
(inches)
B/2 1/2 -3/4
B About 1/2
B is the footing width
The estimated settlement for isolated pad footings with a nominal square dimension of about
three (3) to four (4) feet are tabulated below
Thickness of Compacted
Structural Fill (feet)
Estimated Settlement
(inches)
B/2 3/4 - 1
3B/4 1/2 - 3/4
B is the footing width
The compacted structural fill should be placed and compacted as discussed in the Construction
Considerations, “Fill Placement Recommendations” section of this report, below. The zone of
influence of the footing (at elevations close to the bottom of the footing) is often approximated as
being between two (2) lines subtended at 45 degree angles from each bottom corner of the
footing. The compacted structural fill should extend beyond the zone of influence of the footing
as shown in the sketch below.
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A general and simple rule to apply to the geometry of the compacted structural fill blanket is
that it should extend beyond each edge of the footing a distance which is equal to the fill
thickness.
All footings should be support at an elevation deeper than the maximum depth of frost
penetration for the area. This recommendation includes exterior isolated footings and column
supports. We understand that the code frost depth for the City of Cortez is thirty-two (32) inches.
The post construction differential settlement may be reduced by designing footings that will
apply relatively uniform loads on the support soils. Concentrated loads should be supported by
footings that have been designed to impose similar loads as those imposed by adjacent footings.
Under no circumstances should any footing be supported by more than three (3) feet of
compacted structural fill material unless we are contacted to review the specific conditions
supporting these footing locations.
The design concepts and parameters presented above are based on the soil conditions
encountered in our test borings. We should be contacted during the initial phases of the
foundation excavation at the site to assess the soil support conditions and to verify our
recommendations.
45 degrees 45 degrees
Footing
No Scale
Footing Zone of Influence Concept
Footing Zone of Influence
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5.3 General Shallow Foundation Considerations
Some movement and settlement of any shallow foundation system will occur after construction.
Movement associated with swelling soils also occurs occasionally. Utility line connections
through and foundation or structural component should be appropriately sleeved to reduce the
potential for damage to the utility line. Flexible utility line connections will further reduce the
potential for damage associated with movement of the structure.
6.0 RETAINING STRUCTURES
Laterally loaded walls will be constructed as part of this site development. We understand that
both interior structure retaining walls associated with the main structure as well as exterior
retaining walls will be constructed. The magnitude of the lateral earth pressure forces is partially
dependent on the soil strength characteristics, the geometry of the ground surface adjacent to the
retaining structure, the subsurface water conditions and on surcharge loads.
The retaining structures may be designed using the following un-factored equivalent fluid
pressure values tabulated below for level backfill. We are available to provide specific analysis
for retaining walls that will have sloped backfill or surcharge loads above the retained soil mass.
Lateral Earth Pressure Values
Type of Lateral Earth Pressure Level Native Sandy Clay Soil
Backfill
(pounds per cubic foot/foot)*
Level Granular Soil Backfill
(pounds per cubic foot/foot)
Active 45 35
At-rest 65 55
Passive 345 460
Allowable Coefficient of Friction 0.35 (sandy clay soils) 0.45 (imported structural fill)
The passive wedge of backfill material and retained soil materials should be compacted to at
least ninety (90) percent of the maximum dry density as defined by ASTM D1557, Modified
Proctor, in order to achieve the values tabulated above.
The table below provides estimated for the magnitude of retaining wall rotation/translation to
achieve the active and passive pressures tabulated above.
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Backfill Soil Type Displacement to achieve
active pressures
(per total unit height of wall)
Displacement to achieve
passive pressures
(per total unit height of wall)
Native sandy clay soils 0.01 0.02
Imported Granular Fill 0.001 0.002
Granular soil that is used for the retaining wall backfill may be permeable and may allow water
migration to the foundation support soils. We recommend capping the granular backfill material
with about one and one-half (1½) to two (2) feet of the site clay soil materials. A separation
geotextile may be necessary depending on the grading of the granular backfill materials. It
should be noted that if the site clay soils are used settlement may occur in the backfill mass
which will influence the performance of overlying concrete flatwork or structural components.
Utilizing a granular fill material will decrease the overall consolidation of the backfill mass. This
is discussed in more detail in Section 8.0 below.
The values tabulated above are for well drained backfill soils. The values provided above do
not include any forces due to adjacent surcharge loads or sloped soils. If the backfill soils
become saturated the imposed lateral earth pressures will be significantly higher than those
tabulated above.
The granular imported soil backfill values tabulated above are appropriate for material with an
angle of internal friction of thirty-five (35) degrees, or greater. The granular backfill must be
placed within the retaining structure zone of influence as shown below in order for the lateral
earth pressure values tabulated above for the granular material to be appropriate.
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If a granular backfill is chosen it should not extend to the ground surface. Some granular soils
allow ready water migration which may result in increased water access to the foundation soils.
The upper few feet of the backfill should be constructed using an impervious soil such as silty-
clay and clay soils from the project site.
Backfill should not be placed and compacted behind the retaining structure unless approved by
the project structural engineer. Backfill placed prior to construction of all appropriate structural
members such as floors, or prior to appropriate curing of the retaining wall concrete (if used) may
result in severe damage and/or failure of the retaining structure.
7.0 SUBSURFACE DRAIN SYSTEM
A subsurface drain system must be constructed near the base of all retaining walls. Exterior
retaining structures may be constructed with weep holes to allow subsurface water migration
through the retaining structures.
As discussed earlier in this report, we feel that it is feasible for a temporary subsurface water
condition to develop over the relatively shallow formational materials that underlie the project
site during periods of heavy precipitation or snow melt. Due to the basement areas that will be
incorporated with the structure we recommend that in addition to the basement retaining wall
drain system, a subsurface drain system be constructed adjacent to the exterior sides of the
structure. It may be possible to terminate the drain system along portions of the downslope side
of the structure such as along the north side of the structure to facilitate daylighting the drain
55 Degrees
Retaining wall zone
of influence
Retaining
Structure
Retaining Structure Zone of
Influence Concept, No Scale
Impervious soil
backfill for
upper 2 feet
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system.
We suggest that the system consist of a fabric-wrapped aggregate, or a sand material (some
sands may not need fabric, we are available to discuss this with you) which surrounds a rigid
perforated pipe. We typically do not recommend use of flexible corrugated perforated pipe since
it is not readily possible to establish a uniform gradient of the flexible pipe throughout the drain
system alignment. Corrugated drain tile is perforated throughout the entire circumference of the
pipe and therefore water can escape from the perforations at undesirable locations after being
collected. The nature of the perforations of the corrugated material further decreases its
effectiveness as a subsurface drain conduit.
The drain system pipe should be graded to surface outlets if possible. In areas where this is not
possible a sump vault may be constructed. Typically a minimum gradient of about two (2)
percent is preferred for subsurface drain systems, but site geometry and topography may
influence the actual installed pipe gradient. Water must not be allowed to pool along any portion
of the subsurface drain system. An improperly constructed subsurface drain system may actually
promote water access to undesirable locations. The drain system pipe should be surrounded by
about two (2) to four (4) cubic feet per lineal foot of free draining aggregate or sand. If a sump
vault and pump are incorporated into the subsurface drain system, care should be take so that the
water pumped from the vault does not recirculate through pervious soils and obtain access to
other portions of the structure. A generalized subsurface drain system concept is shown below.
Perforated pipe surrounded by
fabric wrapped free-draining
material. Note: The elevation
of the pipe will depend on the
location in the system at which
the cross section is considered.
Impervious backfill for
upper 2 feet
Compacted backfill that
meets lateral earth pressure
design criteria.
Retaining or
foundation wall
Water proof
membrane or
similar placed on
the foundation wall
and extending
below outer face of
footing
Pervious drain board or
fabric (optional)
Footing
Subsurface Drain System Concept No Scale
Geotextile filter fabric, if appropriate
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There are often aspects of each site and structure which require some tailoring of the subsurface
drain system to meet the needs of individual projects. We are available to provide consultation
for the subsurface drain system for this project, if desired.
Water often will migrate along utility trench excavations in formational material. If the utility
trench extends from areas above the site, this trench may be a source for subsurface water to
access the structure. We suggest that the utility trench backfill be thoroughly compacted to help
reduce the amount of water migration.
8.0 CONCRETE FLATWORK
We understand that both interior and exterior concrete flatwork will be included in the project
design. Concrete flatwork is typically lightly loaded and has a limited capability to resist shear
forces associated with movement within the support soils. It is prudent for the design and
construction of concrete flatwork on this project to be able to accommodate some movement
associated with movement (likely primarily consolidation) of the support soils.
Of particular concern for this project, partially due to our understanding of the basement wall
heights, is post construction consolidation of the basement/corridor retaining wall backfill and
supported slab-on-grade floors. We anticipate that an average percent consolidation of about 1.0
percent may occur in the native sandy clay soils, and an average percent consolidation of about
0.03 percent consolidation may occur in an imported granular fill material, even if these materials
are thoroughly compacted. For example, for a fifteen (15) foot backfill height, we anticipate that
up to about 1.5 inches of settlement may occur in the retaining wall backfill if the native sandy
clay soil materials are used, and about one-half (1/2) inch of settlement may occur if a well
compacted granular fill material is used. These are estimated values. For this reason we suggest
that at minimum a granular backfill material be used for the basement/corridor retaining walls.
Since at least portions of the main level floor system will be structurally supported, it may be
prudent to explore structurally supporting the entire main floor system that will be located over
the retaining wall backfill materials.
8.1 Interior Concrete Slab-on-Grade Floors
A primary goal in the design and construction of interior concrete slab-on-grade floors is to
reduce the amount of post construction movement that may occur in concrete slab-on-grade
floors due to movement of the support soils. A parallel goal is to reduce the potential for damage
to the structure associated with any movement of the slab-on-grade which may occur. There are
limited options available to help mitigate the influence of volume changes in the support soil for
concrete slab-on-grade floors, these include;
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• Preconstruction scarification, moisture conditioning and re-compaction of the natural
soils in areas proposed for support of concrete flatwork, and/or,
• Placement and compaction of granular compacted structural fill material.
Damage associated with movement of interior concrete slab-on-grade floor can be reduced by
designing the floors as “floating” slabs. Floating concrete slabs are not structurally tied to the
foundations or the overlying structure. Interior walls or columns should not be supported on the
interior floor slabs. Movement of interior walls or columns due to movement in the floor slab
can cause severe damage throughout the structure. Interior walls may be structurally supported
from framing above the floor, or interior walls and support columns may be supported on interior
portions of the foundation system.
The only means to completely mitigate the influence of volume changes on the performance of
interior floors is to structurally support the floors. Floors that are suspended by the foundation
system will not be influenced by volume changes in the site soils. The suggestions and
recommendations presented below are intended to help reduce the influence of volume changes
in the support soils on the performance of the concrete slab-on-grade floors.
Interior concrete slab-on-grade floors may be supported by a composite fill blanket which is
composed of a six (6) inch thick lower layer of scarified, moisture conditioned natural soil that is
overlain by a twelve (12) inch thick blanket of compacted structural fill. The scarified fill
material and the compacted structural fill material should be constructed as discussed under the
Construction Considerations, “Fill Placement Considerations” section of this report below.”
Capillary and vapor moisture rise through the slab support soil may provide a source for
moisture in the concrete slab-on-grade floor. This moisture may promote development of mold
or mildew in poorly ventilated areas and may influence the performance of floor coverings and
mastic placed directly on the floor slabs. There are a few options available to help reduce the
migration of capillary moisture and vapor rise into the floor slab.
Comments for Reduction of Capillary Rise
One option to stop capillary rise through the floor slab is to place a layer of clean aggregate
material, such as washed concrete aggregate for the upper four (4) to six (6) inches of fill
material supporting the concrete slabs.
Comments for Reduction of Vapor Rise
To reduce vapor rise through the floors slab a moisture barrier such as a 6 mil (or thicker)
plastic, or similar impervious geotextile material may be placed below the floor slab. The
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American Concrete Institute (ACI) recommends that four (4) inches of “trimmable material” (not
sand) conforming to ASTM D448, No.10 grading be used between the vapor barrier and the
overlying concrete for support of concrete slab-on-grade floors. We have provided the
specifications for ASTM D48 No.10 Sand below.
Grading of ASTM D448 No. 10 Material
Sieve Size Percent Passing Each Sieve
3/8 inch 100
#4 85-100
#100 10 - 30
This type of material may not be locally available therefore we suggest that if an impervious
barrier is used that it should be placed on at two (2) to three (3) inches of fine-grained granular
material, such as crusher reject material to protect it from punctures from the underlying
substrate materials with at least four (4) inches of trimmable material closely conforming to the
D448 No. 10 grading, such as appropriately graded crusher reject material, on top of the barrier
to support the concrete floor slab. This will help reduce the influence of the barrier on the
migration of concrete bleed water and associated concrete curing conditions during construction
of the slab. There are proprietary barriers that are puncture resistant that may not need the
underlying layer of protective material. We do not recommend placement of the concrete
directly on a moisture barrier unless the concrete contractor has had previous experience with
curing of concrete placed in this manner. The project architect, designer and/or builder should be
contacted for the best capillary break for this project.
The project architect, designer and/or builder should be contacted for the best capillary break for
this project. It is not necessary, from a geotechnical engineering perspective, to install capillary
breaks under garage floors unless it is possible that future conversion of the garage into interior
rooms is planned.
The project structural engineer should be contacted to provide steel reinforcement design
considerations for the proposed floor slabs. Any steel reinforcement placed in the slab should be
placed at the appropriate elevations to allow for proper interaction of the reinforcement with
tensile stresses in the slab. Reinforcement steel that is allowed to cure at the bottom of the slab
will not provide adequate reinforcement.
8.2 Exterior Concrete Flatwork Considerations
Exterior concrete flatwork includes concrete driveway slabs, aprons, patios, and walkways. The
desired performance of exterior flatwork typically varies depending on the proposed use of the
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site and each owner’s individual expectations. As with interior flatwork, exterior flatwork is
particularly prone to movement and potential damage due to movement of the support soils. This
movement and associated damage may be reduced by following the recommendations discussed
under interior flatwork, above. Unlike interior flatwork, exterior flatwork may be exposed to
frost heave.
If some movement of exterior flatwork is acceptable, we suggest that the support areas be
prepared by scarification, moisture conditioning and re-compaction of about four (4) inches of
the natural soils followed by placement of about four (4) to six (6) inches of compacted granular
fill material. The scarified material and granular fill materials should be placed as discussed
under the Construction Considerations, “Fill Placement Recommendations” section of this
report, below.
It is important that exterior flatwork be separated from exterior column supports, masonry
veneer, finishes and siding. No support columns, for the structure or exterior decks, should be
placed on exterior concrete unless movement of the columns will not adversely affect the
supported structural components. Movement of exterior flatwork may cause damage if it is in
contact with portions of the structure exterior.
Exterior flatwork should not be placed on soils prepared for support of landscaping vegetation.
Cultivated soils will not provide suitable support for concrete flatwork.
8.3 General Concrete Flatwork Comments
It is relatively common that both interior and exterior concrete flatwork is supported by areas of
fill adjacent to either shallow foundation walls or basement retaining walls. A typical sketch of
this condition is shown below.
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Settlement of the backfill shown above will create a void and lack of soil support for the
portions of the slab over the backfill. Settlement of the fill supporting the concrete flatwork is
likely to cause damage to the slab-on-grade. Settlement and associated damage to the concrete
flatwork may occur when the backfill is relatively deep, even if the backfill is compacted.
If this condition is likely to exist on this site it may be prudent to design the slab to be
structurally supported on the retaining or foundation wall and designed to span to areas away
from the backfill area as designed by the project structural engineer. We are available to discuss
this with you.
9.0 PAVEMENT SECTION THICKNESS DESIGN RECOMMENDATIONS
We performed a California Bearing Ratio (CBR) test on a composite sample of soil obtained
from the project site. Based on the results of the CBR test we used an R-Value of 6 in our
analysis for the pavement section thickness design.
We recommend that the subgrade soils be proof-rolled prior to the scarification and processing
operations. Any soft areas observed during the proof-rolling operations should be removed and
replaced with properly processed materials and/or granular aggregate materials as part of the
subgrade preparation.
The site subgrade pavement section support soils must be scarified to a depth of six (6) inches,
moisture conditioned and compacted prior to placement of the overlying aggregate pavement
Limit of construction
excavation
Foundation or
retaining wall
Concrete Slab-on-grade
Wall backfill area
Wall Backfill and Slab Support
Sketch No Scale
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section materials. The material should be moisture conditioned to within about two (2) percent
of the optimum moisture content and compacted to at least ninety (90) percent of maximum dry
density as determined by the modified Proctor test, ASTM D1557. The surface of the subgrade
soil should be graded and contoured to be approximately parallel to the finished grade of the
pavement surface.
The aggregate materials used within the pavement section should conform to the requirements
outlined in the current Specifications for Road and Bridge Construction, Colorado Department of
Transportation (CDOT). The aggregate base material should be a three-quarter (3/4) inch minus
material that conforms to the CDOT Class 6 aggregate base course specifications and have an R-
value of at least 78. The aggregate sub-base course should conform to the CDOT specifications
for Class 2 material and should have a minimum R-value 70. Other material may be suitable for
use in the pavement section, but materials different than those listed above should be tested and
observed by us prior to inclusion in the project design or construction. Aggregate sub-base and
base-course materials should be compacted to at least ninety-five (95) percent of maximum dry
density as defined by the modified Proctor test, ASTM D1557.
Aggregate base-course and sub-base course locally available that do not meet the above
specifications may be suitable for this project. We are available to review other aggregate
gradations produced by local gravel producers to insure the suitability of the gravel products for
the project. The aggregate base course should have a minimum R-value of 72, and the aggregate
sub-base course should have a minimum R-Value of 65.
9.1 Asphalt Pavement Recommendations
We recommend that the asphalt concrete used on this project be mixed in accordance with a
design prepared by a licensed professional engineer, or an asphalt concrete specialist. We should
be contacted to review the mix design prior to placement at the project site. We recommend that
the asphalt concrete be compacted to between ninety-two (92) and ninety-six (96) percent of the
maximum theoretical density.
We have provided several pavement section design thicknesses below. The structural support
characteristics of each section are approximately equal. The project civil engineer, or contractor
can evaluate the best combination of materials for economic considerations.
We have provided pavement section thicknesses for both 50,000 (standard vehicle use section)
and 125,000 (heavy vehicle use section)- 18,000 pound equivalent single axle loads (18k ESAL).
We are available to provide additional design sections, if these are desired.
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Pavement Section Design Thickness
Light Duty Standard Passenger Car/Truck Use
50,000 18k ESAL
Pavement Section Component Alternative Thicknesses of Each Component
(inches)
Asphalt Concrete 3 3
Class 6 4 10
Class 2 8 0
Reconditioned Subgrade 6 6
Pavement Section Design Thickness
Heavy Vehicle Use
125,000 18k ESAL
Pavement Section Component Alternative Thicknesses of Each Component
(inches)
Asphalt Concrete 4 4 5
Class 6 4 10 6
Class 2 8 0 0
Reconditioned Subgrade 6 6 6
The pavement section thicknesses tabulated above are appropriate for the post-construction
traffic use associated with the fire station. Heavy construction equipment traffic will have a
significant influence on the quality, character, and design life of the pavement sections tabulated
above. If possible we recommend that the asphalt pavement not be placed until completion of
the major construction activity. We are available to discuss this with you as the project
progresses.
9.2 Rigid Concrete Pavement Recommendations
We anticipate that rigid concrete pavement will likely be used for portions of the project
including exterior aprons, and possibly exterior driveway/parking areas. The following
recommendations are based on the American Concrete Institute (ACI) Guide for Design and
Construction of Concrete Parking Lots report 330R-01, strength characteristics (CBR-value) of
the native subgrade soils, and on our experience with concrete paved parking lots in the region.
A modulus of subgrade reaction of 150 pounds per cubic inch may be used for design purposes.
PN: 54077GE
January 28, 2016
35
Our recommendations are as follows;
• For the proposed main parking area that will service light vehicular traffic only, a
minimum concrete mat thickness of five (5) inches should be used. This section is valid
for an average daily truck (ADTT) of less than ten (10).
• For areas that will be exposed to heavy truck traffic on a regular basis a minimum
concrete mat thickness of six (6) inches should be used.
The concrete mat should be supported by a minimum thickness of six (6) inches of three-quarter
(3/4) inch minus aggregate base course material that meets the specifications tabulated in section
9.1 above. We are available to review aggregate gradations produced by local gravel producers
to insure the suitability of the gravel products for the project. The aggregate materials should be
compacted to at least ninety-five (95) percent of maximum dry density as defined by AASHTO
T-180 or ASTM D 1557, Modified Proctor test. The upper six (6) inches of subgrade support
soils should be scarified and compacted to at least ninety (90) percent of maximum dry density as
defined by AASHTO T-180 or ASTM D1557, Modified Proctor test prior to placement of the
aggregate base course.
A concrete with a minimum twenty-eight (28) day compressive strength of 4,500 pounds per
square inch (psi) should be used. Joint spacing should not exceed twelve and one-half (12½) feet
for a slab thickness of five (5) inches and should not exceed fifteen (15) feet for a slab thickness
of six (6) inches. The recommendations for minimum concrete strength presented here are based
on the ACI recommendations. The site specific structural engineering design recommendations
should take precedent over those listed in this report. The project structural engineer should be
contacted for steel reinforcement design. We are available to discuss our recommendations with
the project structural engineer as needed.
9.3 General Parking Area Considerations
Water intrusion into the pavement section support materials will negatively influence the
performance of the parking lot surface. Water from irrigation, water from natural sources that
migrates into the soils beneath landscapes surface and water from any source that gains access to
the support materials can all decrease the life of the parking lot surface. Care should be taken
along curbs and any edge of the parking lot to develop an interface between the material that will
reduce subsurface and surface water migration into the support soil and pavement section
materials. Landscape islands and other irrigated features often promote water migration since no
surface flow from these features typically occurs. The same can occur along perimeter cub areas.
PN: 54077GE
January 28, 2016
36
Water will often migrate along the interface of concrete curbs and gutter areas early in the life
of any parking area. The tendency for this type of migration often decreases with time, but can
be reduced by compaction of materials along the outside base of curb areas adjacent to the
interface of the concrete curb and the underlying soil prior to placement of landscaping soil
above this interface.
10.0 CONSTRUCTION CONSIDERATIONS
This section of the report provides comments, considerations and recommendations for aspects
of the site construction which may influence, or be influenced by the geotechnical engineering
considerations discussed above. The information presented below is not intended to discuss all
aspects of the site construction conditions and considerations that may be encountered as the
project progresses. If any questions arise as a result of our recommendations presented above, or
if unexpected subsurface conditions are encountered during construction we should be contacted
immediately.
10.1 Fill Placement Recommendations
There are several references throughout this report regarding both natural soil and compacted
structural fill recommendations. The recommendations presented below are appropriate for the
fill placement considerations discussed throughout the report above.
All areas to receive fill, structural components, or other site improvements should be properly
prepared and grubbed at the initiation of the project construction. The grubbing operations
should include scarification and removal of organic material and soil. No fill material or
concrete should be placed in areas where existing vegetation or fill material exist.
10.1.1 Natural Soil Fill
Any natural soil used for any fill purpose should be free of all deleterious material, such as
organic material and construction debris. Natural soil fill includes excavated and replaced
material or in-place scarified material.
The natural soils should be moisture conditioned, either by addition of water to dry soils, or by
processing to allow drying of wet soils. The proposed fill materials should be moisture
conditioned to between about optimum and about two (2) percent above optimum soil moisture
content. This moisture content can be estimated in the field by squeezing a sample of the soil in
the palm of the hand. If the material easily makes a cast of soil which remains in-tact, and a
minor amount of surface moisture develops on the cast, the material is close to the desired
PN: 54077GE
January 28, 2016
37
moisture content. Material testing during construction is the best means to assess the soil
moisture content.
Moisture conditioning of clay or silt soils may require many hours of processing. If possible,
water should be added and thoroughly mixed into fine grained soil such as clay or silt the day
prior to use of the material. This technique will allow for development of a more uniform
moisture content and will allow for better compaction of the moisture conditioned materials.
The moisture conditioned soil should be placed in lifts that do not exceed the capabilities of the
compaction equipment used and compacted to at least ninety (90) percent of maximum dry
density as defined by ASTM D1557, modified Proctor test. We typically recommend a
maximum fill lift thickness of six (6) inches for hand operated equipment and eight (8) to ten
(10) inches for larger equipment. Care should be exercised in placement of utility trench backfill
so that the compaction operations do not damage the underlying utilities.
Typically the maximum lift thickness is about six (6) to eight (8) inches, therefore the
maximum allowable rock size for natural soil fill is about six (6) inches. If smaller compaction
equipment is being used, such as walk behind compactors in trenches, the maximum rock size
should be less than about three (3) inches.
10.1.2 Granular Compacted Structural Fill
Granular compacted structural fill is referenced in numerous locations throughout the text of
this report. Granular compacted structural fill should be constructed using an imported
commercially produced rock product such as aggregate road base. Many products other than
road base, such as clean aggregate or select crusher fines may be suitable, depending on the
intended use. If a specification is needed by the design professional for development of project
specifications, a material conforming to the Colorado Department of Transportation (CDOT)
“Class 6” aggregate road base material can be specified. This specification can include an option
for testing and approval in the event the contractor’s desired material does not conform to the
Class 6 aggregate specifications. We have provided the CDOT Specifications for Class 6
material below
Grading of CDOT Class 6 Aggregate Base-Course Material
Sieve Size Percent Passing Each Sieve
¾ inch 100
#4 30 – 65
#8 25 – 55
#200 3 – 12
Liquid Limit less than 30
PN: 54077GE
January 28, 2016
38
All compacted structural fill should be moisture conditioned and compacted to at least ninety
(90) percent of maximum dry density as defined by ASTM D1557, modified Proctor test. Areas
where the structural fill will support traffic loads under concrete slabs or asphalt concrete should
be compacted to at least ninety-five (95) percent of maximum dry density as defined by ASTM
D1557, modified Proctor test.
Although clean-screened or washed aggregate may be suitable for use as structural fill on sites
with sand or non-expansive silt soils, or on sites where shallow subsurface water is present, clean
aggregate materials must not be used on any site where expansive soils exist due to the potential
for water to accumulate in the voids of the clean aggregate materials.
Clean aggregate fill, if appropriate for the site soil conditions, must not be placed in lifts
exceeding eight (8) inches and each lift should be thoroughly vibrated, preferably with a plate-
type vibratory compactor prior to placing overlying lifts of material or structural components.
We should be contacted prior to the use of clean aggregate fill materials to evaluate their
suitability for use on this project.
10.2 Excavation Considerations
Unless a specific classification is performed, the site soils should be considered as an
Occupational Safety and Health Administration (OSHA) Type C soil and should be sloped and/or
benched according to the current OSHA regulations. Excavations should be sloped and benched
to prevent wall collapse. Any soil can release suddenly and cave unexpectedly from excavation
walls, particularly if the soils is very moist, or if fractures within the soil are present. Daily
observations of the excavations should be conducted by OSHA competent site personnel to
assess safety considerations.
We did not encounter free subsurface water in our test borings at the depths that we anticipate
the project excavation will extend. If water is encountered during construction, it may be
necessary to dewater excavations to provide for suitable working conditions.
We encountered formational material in our test borings. We suspect that it may be difficult to
excavate this material using conventional techniques. If blasting is planned it must be conducted
strategically to reduce the affect of the blasting on the support characteristics of the site materials
and the stability of adjacent slopes. We typically recommend that where possible blasting be
avoided, however blasting is often needed to aid in the excavation of the site to develop the
desired footing support elevations. It is typical to have about two (2) to three (3) feet of loose
angular clasts of rock, commonly called “shot-rock” below the desired bottom of excavation
elevations. This material is not suitable for support of structural components and should be
removed and replaced with compacted structural fill in areas proposed for support of structural
PN: 54077GE
January 28, 2016
39
components.
If possible excavations should be constructed to allow for water flow from the excavation the
event of precipitation during construction. If this is not possible it may be necessary to remove
water from snowmelt or precipitation from the foundation excavations to help reduce the
influence of this water on the soil support conditions and the site construction characteristics.
10.2.1 Excavation Cut Slopes
We anticipate that some permanent excavation cut slopes may be included in the site
development. Temporary cut slopes should not exceed five (5) feet in height and should not be
steeper than about one to one (1:1, horizontal to vertical) for most soils. Permanent cut slopes of
greater than five (5) feet or steeper than two and one-half to one (2½:1, h:v) must be analyzed on
a site specific basis.
10.3 Utility Considerations
Subsurface utility trenches will be constructed as part of the site development. Utility line
backfill often becomes a conduit for post construction water migration. If utility line trenches
approach the proposed project site from above, water migrating along the utility line and/or
backfill may have direct access to the portions of the proposed structure where the utility line
penetrations are made through the foundation system. The foundation soils in the vicinity of the
utility line penetration may be influenced by the additional subsurface water. There are a few
options to help mitigate water migration along utility line backfill. Backfill bulkheads
constructed with high clay content soils and/or placement of subsurface drains to promote utility
line water discharge through the foundation drain system.
Some movement of all structural components is normal and expected. The amount of
movement may be greater on sites with problematic soil conditions. Utility line penetrations
through any walls or floor slabs should be sleeved so that movement of the walls or slabs does
not induce movement or stress in the utility line. Utility connections should be flexible to allow
for some movement of the floor slab.
If utility line trenches are excavated using blasting techniques it is relatively common for
surface and subsurface water to migrate along the fractures in the rock that may be created by
blasting. If this water gains access to a utility line trench that has a gradient down toward the
structure the water may gain access to the foundation support materials and/or subsurface
portions of the proposed structure. Provisions should be made in the project construction plans
to create an impervious barrier to prevent water from migrating into undesirable locations.
PN: 54077GE
January 28, 2016
40
10.4 Exterior Grading and Drainage Comments
The ground surface adjacent to the structure should be sloped to promote water flow away from
the foundation system and flatwork. Snow storage areas should not be located in areas which
will allow for snowmelt water access to support soils for the foundation system or flatwork.
Water flow from the roof of the structure should be captured and directed away from the
structure. If the roof water is collected in an eave gutter system, or similar, the discharge points
of the system must be located away from areas where the water will have access to the
foundation backfill or any structure support soils. If downspouts are used, provisions should be
made to either collect or direct the water away from the structure.
The project civil engineering consultant or builder should develop a drainage scheme for the
site. We typically suggest a minimum fall of about eight (8) to ten (10) percent away from the
structure, in the absence of design criteria from others. Care should be taken to not direct water
onto adjacent property or to areas that would negatively influence existing structures or
improvements.
10.5 Landscaping Considerations
We recommend against construction of landscaping which requires excessive irrigation.
Generally landscaping which uses abundant water requires that the landscaping contractor install
topsoil which will retain moisture. The topsoil is often placed in flattened areas near the
structure to further trap water and reduce water migration from away from the landscaped areas.
Unfortunately almost all aspects of landscape construction and development of lush vegetation
are contrary to the establishment of a relatively dry area adjacent to the foundation walls. Excess
water from landscaped areas near the structure can migrate to the foundation system or flatwork
support soils, which can result in volume changes in these soils.
A relatively common concept used to collect and subsequently reduce the amount of excess
irrigation water is to glue or attach an impermeable geotextile fabric or heavy mill plastic to the
foundation wall and extend it below the topsoil which is used to establish the landscape
vegetation. A thin layer of sand can be placed on top of the geotextile material to both protect
the geotextile from punctures and to serve as a medium to promote water migration to the
collection trench and perforated pipe. The landscape architect or contractor should be contacted
for additional information regarding specific construction considerations for this concept which
is shown in the sketch below.
PN: 54077GE
January 28, 2016
41
Shallow Landscaping Drain Concept No Scale
Foundation Wall
Approximate
limit
foundation
excavation
backfill
Impermeable geotextile
material, lapped and
glued to the foundation
wall above grade
Perforated pipe
surrounded by free-
draining material
Filter Fabric
PN: 54077GE
January 28, 2016
42
A free draining aggregate or sand may be placed in the collection trench around the perforated
pipe. The perforated pipe should be graded to allow for positive flow of excess irrigation water
away from the structure or other area where additional subsurface water is undesired. Preferably
the geotextile material should extend at least ten (10) or more feet from the foundation system.
Care should be taken to not place exterior flatwork such as sidewalks or driveways on soils that
have been tilled and prepared for landscaping. Tilled soils will settle which can cause damage to
the overlying flatwork. Tilled soils placed on sloped areas often “creep” down-slope. Any
structure or structural component placed on this material will move down-slope with the tilled
soil and may become damaged.
10.6 Soil Sulfate Content, Corrosion Issues
The requested scope of our services did not include assessment of the chemical constituents of
corrosion potential of the site soils. Most soils in southwest Colorado are not typically corrosive
to concrete. There has not been a history of damage to concrete due to sulfate corrosion in the
area.
We are available to perform soluble sulfate content tests to assess the corrosion potential of the
soils on concrete if desired.
10.7 Radon Issues
The requested scope of service of this report did not include assessment of the site soils for
radon production. Many soils and formational materials in western Colorado produce Radon gas.
The structure should be appropriately ventilated to reduce the accumulation of Radon gas in the
structure. Several Federal Government agencies including the Environmental Protection Agency
(EPA) have information and guidelines available for Radon considerations and home
construction. If a radon survey of the site soils is desired, please contact us.
11.0 CONSTRUCTION MONITORING AND TESTING
Construction monitoring including engineering observations and materials testing during
construction is a critical aspect of the geotechnical engineering contribution to any project.
Unexpected subsurface conditions are often encountered during construction. The site foundation
excavation should be observed by the geotechnical engineer or a representative during the early
stages of the site construction to verify that the actual subsurface soil and water conditions were
properly characterized as part of field exploration, laboratory testing and engineering analysis. If
PN: 54077GE
January 28, 2016
43
the subsurface conditions encountered during construction are different than those that were the
basis of the geotechnical engineering report then modifications to the design may be
implemented prior to placement of fill materials or foundation concrete.
Compaction testing of fill material should be performed throughout the project construction so
that the engineer and contractor may monitor the quality of the fill placement techniques being
used at the site. Generally we recommend that compaction testing be performed for any fill
material that is placed as part of the site development. Compaction tests should be performed on
each lift of material placed in areas proposed for support of structural components. In addition to
compaction testing we recommend that the grain size distribution, clay content and swell
potential be evaluated for any imported materials that are planned for use on the site. Concrete
tests should be performed on foundation concrete and flatwork. If asphaltic concrete is placed
for driveways or aprons near the structure we are available to provide testing of these materials
during placement. We are available to develop a testing program for soil, aggregate materials,
concrete and asphaltic concrete for this project.
12.0 CONCLUSIONS AND CONSIDERATIONS
The information presented in this report is based on our understanding of the proposed
construction that was provided to us and on the data obtained from our field and laboratory
studies. We recommend that we be contacted during the design and construction phase of this
project to aid in the implementation of our recommendations. Please contact us immediately if
you have any questions, or if any of the information presented above is not appropriate for the
proposed site construction.
The recommendations presented above are intended to be used only for this project site and the
proposed construction which was provided to us. The recommendations presented above are not
suitable for adjacent project sites, or for proposed construction that is different than that outlined
for this study.
Our recommendations are based on limited field and laboratory sampling and testing.
Unexpected subsurface conditions encountered during construction may alter our
recommendations. We should be contacted during construction to observe the exposed
subsurface soil conditions to provide comments and verification of our recommendations.
We are available to review and tailor our recommendations as the project progresses and
additional information which may influence our recommendations becomes available.
PN: 54077GE
January 28, 2016
44
Please contact us if you have any questions, or if we may be of additional service.
Respectfully submitted,
TRAUTNER GEOTECH
Jonathan P. Butler, P.E.
Staff Geotechnical Engineer
PN: 54077GE
January 28, 2016
APPENDIX A
Logs of Test Borings
Field Engineer : J. Butler
Hole Diameter : 4" Solid
Drilling Method : Continuous Flight Auger
Sampling Method : Bag Sample
Date Drilled : 01/07/2016
Total Depth (approx.) : 2.5 feet
Location : See Figure 1 in Report
LOG OF BORING TB - 1
PN:54077GE
109 W Main Street, Room 302Montezuma County Commissioners
Combined Court BuildingMontezuma County
Depthin
feet
0
1
2
3
4
5
DESCRIPTION
Sample Type
Mod. California Sampler
Bag Sample
Standard Split Spoon
Water Level
Water Level During Drilling
Water Level After Drilling
CLAY, sandy, soft to medium stiff, very moist, red
FORMATIONAL MATERIAL at two (2) feet, sandstone, very hard, tan, Dakota Sandstone and Burro Canyon Formation
Auger refusal at two and one-half (2.5) feet
US
CS
CL
GR
AP
HIC
Sam
ples
Blo
w C
ount
Wat
er L
evel
REMARKS
Field Engineer : J. Butler
Hole Diameter : 4" Solid
Drilling Method : Continuous Flight Auger
Sampling Method : Standard Split Spoon
Date Drilled : 01/07/2016
Total Depth (approx.) : 5 feet
Location : See Figure 1 in Report
LOG OF BORING TB - 2
PN:54077GE
109 W Main Street, Room 302Montezuma County Commissioners
Combined Court BuildingMontezuma County
Depthin
feet
0
1
2
3
4
5
6
DESCRIPTION
Sample Type
Mod. California Sampler
Bag Sample
Standard Split Spoon
Water Level
Water Level During Drilling
Water Level After Drilling
CLAY, sandy, stiff, very moist, red
CLAY, sandy, stiff, moist, tan
FORMATIONAL MATERIAL at three (3) feet, sandstone, hard to very hard, tan, Dakota Sandstone and Burro Canyon Formation
Auger refusal at five (5) feet
US
CS
CL
CL
GR
AP
HIC
Sam
ples
Blo
w C
ount
Wat
er L
evel
REMARKS
50/1
Field Engineer : J. Butler
Hole Diameter : NQ
Drilling Method : Wireline Core
Sampling Method : NQ Core
Date Drilled : 1/20/2016
Total Depth : 22 feet
Location : See Figure in Report
LOG OF BORING TC-2A
PN:54077GE
108 W Main Street, Room 302Montezuma County Commissioners
Combined Court BuildingMontezuma County
Depthin
feet
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
DESCRIPTION
NQ Core
US
CS
GR
AP
HIC
Run
dep
th
Recovery and R.Q.D.
Top of First Run at two and one-half (2.5) feet
Recovery= 94% R.Q.D= 60%
Bottom of First Run at seven (7) feetTop of Second Run at seven (7) feet
Recovery= 100%R.Q.D.= 14%
Bottom of Second Run at twelve (12) feet Top of Third Run at twelve (12) feet
Recovery= 97%R.Q.D.= 29%
Bottom of Third Run at seventeen (17) feetTop of Fourth Run at seventeen (17) feet
Recovery=100%R.Q.D.= 40%
Bottom of Fourth Run at twenty-two (22) feet
CLAY, sandy, medium stiff, moist, red
FORMATIONAL MATERIAL at two (2) feet, Dakota Sandstone and Burro Canyon Formation, sandstone, very hard, slightly moist, tan, Auger refusal at two and one-half (2.5) feet, moderately fractured sandstone, very hard, tan to white
Highly fractured sandstone, tan, Dakota Sandstone and Burro Canyon Formation
Clayey sandstone, highly fractured, tan to brown, Dakota Sandstone and Burro Canyon Formation
SUBSURFACE WATER ENCOUNTERED IN FRACTURE AT 16 FEET
Claystone and shale, highly fractured, brown to gray, Dakota Sandstone and Burro Canyon Formation
Sandstone, highly fractured, tan, Dakota Sandstone and Burro Canyon Formation
Bottom of test core at twenty-two (22) feet
CL
LOG OF BORING TB - 3
PN:54077GE
109 W Main Street, Room 302Montezuma County Commissioners
Combined Court BuildingMontezuma County
Depthin
feet
0
1
2
3
4
5
DESCRIPTION
Sample Type
Mod. California Sampler
Bag Sample
Standard Split Spoon
Water Level
Water Level During Drilling
Water Level After Drilling
CLAY, sandy, medium stiff, moist, red
FORMATIONAL MATERIAL at one and one-half (1.5) feet, sandstone, upper one (1) foot is weathered then became very hard, tan, Dakota Sandstone and Burro Canyon Formation
Auger refusal at three (3) feet
US
CS
CL
GR
AP
HIC
Sam
ples
Blo
w C
ount
Wat
er L
evel
REMARKS
Field Engineer : J. Butler
Hole Diameter : 4" Solid
Drilling Method : Continuous Flight Auger
Sampling Method : Mod. California Sampler
Date Drilled : 01/07/2016
Total Depth (approx.) : 3 feet
Location : See Figure 1 in Report
40/6
50/5
Field Engineer : J. Butler
Hole Diameter : 4" Solid
Drilling Method : Continuous Flight Auger
Sampling Method : No Sampling
Date Drilled : 01/20/2016
Total Depth (approx.) : 2.5 feet
Location : See Figure 1 in Report
LOG OF BORING TB - 3A
PN:54077GE
109 W Main Street, Room 302Montezuma County Commissioners
Combined Court BuildingMontezuma County
Depthin
feet
0
1
2
3
4
5
DESCRIPTION
Sample Type
Mod. California Sampler
Bag Sample
Standard Split Spoon
Water Level
Water Level During Drilling
Water Level After Drilling
CLAY, sandy, soft to medium stiff, moist to very moist, red
FORMATIONAL MATERIAL at two (2) feet, sandstone, very hard, slightly moist, tan, Dakota Sandstone and Burro Canyon Formation
Auger refusal at two and one-half (2.5) feet
US
CS
CL
GR
AP
HIC
Sam
ples
Blo
w C
ount
Wat
er L
evel
REMARKS
Field Engineer : J. Butler
Hole Diameter : 4" Solid
Drilling Method : Continuous Flight Auger
Sampling Method : Mod. California Sampler
Date Drilled : 01/07/2016
Total Depth (approx.) : 38.5 feet
Location : See Figure 1 in Report
LOG OF BORING TB - 4
PN:54077GE
109 W Main Street, Room 302Montezuma County Commissioners
Combined Court BuildingMontezuma County
Depthin
feet
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
DESCRIPTION
Sample Type
Mod. California Sampler
Bag Sample
Standard Split Spoon
Water Level
Water Level During Drilling
Water Level After Drilling
CLAY, sandy, soft to medium dense, moist to very moist, red
FORMATIONAL MATERIAL at three (3) feet, sandstone caprock for one (1) foot, very hard, tan, Dakota Sandstone and Burro Canyon Formation
Sandstone with interbedded claystone layers, very hard, tan, Dakota Sandstone and Burro Canyon Formation
Claystone at ten (10) feet, hard/very stiff, moist, brown, Dakota Sandstone and Burro Canyon Formation
Interbedded sandstone and claystone, very hard, tan to brown
Bottom of test boring at thirty-eight (38) feet
US
CS
CL
GR
AP
HIC
Sam
ples
Blo
w C
ount
50/1
50/3
25/650/6
15/625/635/6
50/1
Wat
er L
evel
REMARKS
Field Engineer : J. Butler
Hole Diameter : 4" Solid
Drilling Method : Continuous Flight Auger
Sampling Method : Mod. California Sampler
Date Drilled : 01/07/2016
Total Depth (approx.) : 18 feet
Location : See Figure 1 in Report
LOG OF BORING TB - 5
PN:54077GE
109 W Main Street, Room 302Montezuma County Commissioners
Combined Court BuildingMontezuma County
Depthin
feet
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
DESCRIPTION
Sample Type
Mod. California Sampler
Bag Sample
Standard Split Spoon
Water Level
Water Level During Drilling
Water Level After Drilling
CLAY, sandy, soft, moist, red
CLAY, SAND, white chemical cementing, hard, slightly moist, tan to white
FORMATIONAL MATERIAL at eight (8) feet, sandstone, very hard, slightly moist, tan to brown, Dakota Sandstone and Burro Canyon Formation
Sandy claystone, very hard, moist, brown, Dakota Sandstone and Burro Canyon Formation
Auger refusal at eighteen (18) feet
US
CS
CL
CL-SCG
RA
PH
IC
Sam
ples
Blo
w C
ount
25/6
30/6
25/6
50/5
50/6
50/6
Wat
er L
evel
REMARKS
Field Engineer : J. Butler
Hole Diameter : 4" Solid
Drilling Method : Continuous Flight Auger
Sampling Method : Mod. California Sampler
Date Drilled : 01/07/2016
Total Depth (approx.) : 24 feet
Location : See Figure 1 in Report
LOG OF BORING TB - 6
PN:54077GE
109 W Main Street, Room 302Montezuma County Commissioners
Combined Court BuildingMontezuma County
Depthin
feet
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
DESCRIPTION
Sample Type
Mod. California Sampler
Bag Sample
Standard Split Spoon
Water Level
Water Level During Drilling
Water Level After Drilling
CLAY, sandy, soft, very moist, red
CLAY, SAND, some white chemical deposits, very stiff/very dense, slightly moist, red and tan
FORMATIONAL MATERIAL at eight and one-half (8.5) feet, sandstone, very hard, slightly moist, tan, Dakota Sandstone and Burro Canyon Formation
Clayey sandstone, to sandy claystone, hard to very hard, moist, brown to tan, Dakota Sandstone and Burro Canyon Formation
Claystone at twenty (20) feet, hard, moist, brown, Dakota Sandstone and Burro Canyon Formation
Sandstone at twenty-three and one-half (23.5) feet, very hard, Dakota Sandstone and Burro Canyon Formation
Auger refusal at twenty-four (24) feet
US
CS
CL
CL-SC
GR
AP
HIC
Sam
ples
Blo
w C
ount
Wat
er L
evel
REMARKS
18/630/6
50/3
40/650/5
Field Engineer : J. Butler
Hole Diameter : 4" Solid
Drilling Method : Continuous Flight Auger
Sampling Method : Mod. California Sampler
Date Drilled : 01/07/2016
Total Depth (approx.) : 22.5 feet
Location : See Figure 1 in Report
LOG OF BORING TB - 7
PN:54077GE
109 W Main Street, Room 302Montezuma County Commissioners
Combined Court BuildingMontezuma County
Depthin
feet
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
DESCRIPTION
Sample Type
Mod. California Sampler
Bag Sample
Standard Split Spoon
Water Level
Water Level During Drilling
Water Level After Drilling
CLAY, sandy, soft, very moist, red
CLAY, SAND, dense, slightly moist, red and tan
FORMATIONAL MATERIAL at three and one-half (3.5) feet, sandstone, very hard, slightly moist, tan, Dakota Sandstone and Burro Canyon Formation
Clayey sandstone, very hard, moist, brown to tan, Dakota Sandstone and Burro Canyon Formation
Sandy Claystone, very hard, moist, brown to tan, Dakota Sandstone and Burro Canyon Formation
Sandstone at twenty-one (21) feet, very hard, Dakota Sandstone and Burro Canyon Formation
Auger refusal at twenty two and one-half (22.5) feet
US
CS
CL
CL
GR
AP
HIC
Sam
ples
Blo
w C
ount
Wat
er L
evel
REMARKS
35/650/2
30/650/2
80/6
Field Engineer : J. Butler
Hole Diameter : 4" Solid
Drilling Method : Continuous Flight Auger
Sampling Method : Mod. California Sampler
Date Drilled : 01/07/2016
Total Depth (approx.) : 5 feet
Location : See Figure 1 in Report
LOG OF BORING TB - 8
PN:54077GE
109 W Main Street, Room 302Montezuma County Commissioners
Combined Court BuildingMontezuma County
Depthin
feet
0
1
2
3
4
5
6
DESCRIPTION
Sample Type
Mod. California Sampler
Bag Sample
Standard Split Spoon
Water Level
Water Level During Drilling
Water Level After Drilling
CLAY, sandy, soft to medium stiff, very moist, red
CLAY, sandy, stiff, slightly moist, tan
FORMATIONAL MATERIAL at three (3) feet, sandstone, hard to very hard, slightly moist, tan, Dakota Sandstone and Burro Canyon Formation
Auger refusal at five (5) feet
US
CS
CL
CL
GR
AP
HIC
Sam
ples
Blo
w C
ount
30/6
50/1
Wat
er L
evel
REMARKS
Field Engineer : J. Butler
Hole Diameter : 4" Solid
Drilling Method : Continuous Flight Auger
Sampling Method : Mod. California Sampler
Date Drilled : 01/07/2016
Total Depth (approx.) : 5.5 feet
Location : See Figure 1 in Report
LOG OF BORING TB - 9
PN:54077GE
109 W Main Street, Room 302Montezuma County Commissioners
Combined Court BuildingMontezuma County
Depthin
feet
0
1
2
3
4
5
6
DESCRIPTION
Sample Type
Mod. California Sampler
Bag Sample
Standard Split Spoon
Water Level
Water Level During Drilling
Water Level After Drilling
CLAY, sandy, medium stiff, moist, red
CLAY, sandy, stiff, moist, tan
FORMATIONAL MATERIAL at three and one-half (3.5) feet, sandstone, very hard, slightly moist, tan, Dakota Sandstone and Burro Canyon Formation
Auger refusal at five and one-half (5.5) feet
US
CS
CL
CL
GR
AP
HIC
Sam
ples
Blo
w C
ount
30/6
50/1
Wat
er L
evel
REMARKS
Field Engineer : J. Butler
Hole Diameter : 4" Solid
Drilling Method : Continuous Flight Auger
Sampling Method : Mod. California Sampler
Date Drilled : 01/07/2016
Total Depth (approx.) : 7.5 feet
Location : See Figure 1 in Report
LOG OF BORING TB - 10
PN:54077GE
109 W Main Street, Room 302Montezuma County Commissioners
Combined Court BuildingMontezuma County
Depthin
feet
0
1
2
3
4
5
6
7
8
DESCRIPTION
Sample Type
Mod. California Sampler
Bag Sample
Standard Split Spoon
Water Level
Water Level During Drilling
Water Level After Drilling
CLAY, sandy, medium stiff, moist, red
CLAY, sandy, stiff, slightly moist, red and tan
FORMATIONAL MATERIAL at three and one-half (3.5) feet, sandstone, very hard, slightly moist, tan, Dakota Sandstone and Burro Canyon Formation
Auger refusal at seven and one-half (7.5) feet
US
CS
CL
CL
GR
AP
HIC
Sam
ples
Blo
w C
ount
Wat
er L
evel
REMARKS
13/6
6/6
3/6
10/6
20/6
15/6
50/6
50/2
Field Engineer : J. Butler
Hole Diameter : NQ
Drilling Method : Wireline Core
Sampling Method : NQ Core
Date Drilled : 1/20/2016
Total Depth : 12 feet
Location : See Figure in Report
LOG OF BORING TC-10A
PN:54077GE
108 W Main Street, Room 302Montezuma County Commissioners
Combined Court BuildingMontezuma County
Depthin
feet
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
DESCRIPTION
NQ Core
CLAY, sandy, medium stiff, moist, red
CLAY, sandy, stiff, slightly moist, tan
WEATHERED FORMATIONAL MATERIAL at five and one-half (5.5) feet, Dakota Sandstone and Burro Canyon Formation, sandy claystone, hard, moist, tan
Sandstone, moderately fractured, tan to white, Dakota Sandstone and Burro Canyon Formation
Bottom of test core at twelve (12) feet
US
CS
CL
CL
GR
AP
HIC
Run
dep
th
Recovery and R.Q.D.
Top of First Run at five and one-half (5.5) feet
Recovery= 100% R.Q.D= 0%
Bottom of First Run at seven (7) feetTop of Second Run at seven (7) feet
Recovery= 100%R.Q.D.= 85%
Bottom of Second Run at twelve (12) feet
Field Engineer : J. Butler
Hole Diameter : 4" Solid
Drilling Method : Continuous Flight Auger
Sampling Method : Mod. California Sampler
Date Drilled : 01/07/2016
Total Depth (approx.) : 9.5 feet
Location : See Figure 1 in Report
LOG OF BORING TB - 11
PN:54077GE
109 W Main Street, Room 302Montezuma County Commissioners
Combined Court BuildingMontezuma County
Depthin
feet
0
1
2
3
4
5
6
7
8
9
10
DESCRIPTION
Sample Type
Mod. California Sampler
Bag Sample
Standard Split Spoon
Water Level
Water Level During Drilling
Water Level After Drilling
CLAY, sandy, soft, moist, red
CLAY and SAND, white chemical deposits, very stiff, very dense, slightly moist, red and tan
FORMATIONAL MATERIAL at seven (7) feet, sandstone, hard to very hard, slightly moist, tan, Dakota Sandstone and Burro Canyon Formation
Auger refusal at nine and one-half (9.5) feet
US
CS
CL
CL-SC
GR
AP
HIC
Sam
ples
Blo
w C
ount
Wat
er L
evel
REMARKS
15/6
40/6
Field Engineer : J. Butler
Hole Diameter : 4" Solid
Drilling Method : Continuous Flight Auger
Sampling Method : Mod. California Sampler
Date Drilled : 01/07/2016
Total Depth (approx.) : 6.5 feet
Location : See Figure 1 in Report
LOG OF BORING TB - 12
PN:54077GE
109 W Main Street, Room 302Montezuma County Commissioners
Combined Court BuildingMontezuma County
Depthin
feet
0
1
2
3
4
5
6
7
DESCRIPTION
Sample Type
Mod. California Sampler
Bag Sample
Standard Split Spoon
Water Level
Water Level During Drilling
Water Level After Drilling
CLAY, sandy, soft, moist, red
CLAY and SAND, some chemical deposits, very dense, slightly moist, red and tan
FORMATIONAL MATERIAL at four (4) feet, sandstone, hard to very hard, slightly moist, tan, Dakota Sandstone and Burro Canyon Formation
Auger refusal at six and one-half (6.5) feet
US
CS
CL
CL-SC
GR
AP
HIC
Sam
ples
Blo
w C
ount
Wat
er L
evel
REMARKS
Field Engineer : J. Butler
Hole Diameter : 4" Solid
Drilling Method : Continuous Flight Auger
Sampling Method : Mod. California Sampler
Date Drilled : 01/07/2016
Total Depth (approx.) : 7.5 feet
Location : See Figure 1 in Report
LOG OF BORING TB - 13
PN:54077GE
109 W Main Street, Room 302Montezuma County Commissioners
Combined Court BuildingMontezuma County
Depthin
feet
0
1
2
3
4
5
6
7
8
DESCRIPTION
Sample Type
Mod. California Sampler
Bag Sample
Standard Split Spoon
Water Level
Water Level During Drilling
Water Level After Drilling
CLAY, sandy, soft, very moist, red
CLAY and SAND, chemical deposits, stiff to very stiff, slightly moist, red and tan
FORMATIONAL MATERIAL at seven (7) feet, sandstone, very hard, slightly moist, tan, Dakota Sandstone and Burro Canyon Formation
Auger refusal at seven and one-half (7.5) feet
US
CS
CL
CL-SC
GR
AP
HIC
Sam
ples
Blo
w C
ount
13/6
13/6
50/1
Wat
er L
evel
REMARKS
Field Engineer : J. Butler
Hole Diameter : 4" Solid
Drilling Method : Continuous Flight Auger
Sampling Method : Mod. California Sampler
Date Drilled : 01/07/2016
Total Depth (approx.) : 9.5 feet
Location : See Figure 1 in Report
LOG OF BORING TB - 14
PN:54077GE
109 W Main Street, Room 302Montezuma County Commissioners
Combined Court BuildingMontezuma County
Depthin
feet
0
1
2
3
4
5
6
7
8
9
10
DESCRIPTION
Sample Type
Mod. California Sampler
Bag Sample
Standard Split Spoon
Water Level
Water Level During Drilling
Water Level After Drilling
CLAY, sandy, medium stiff, moist, red
CLAY and SAND, chemical deposits and cemented soils, stiff, dense, slightly moist, red and tan
Auger Refusal on FORMATIONAL MATERIAL at nine and one-half (9.5) feet, sandstone, very hard, slightly moist, tan, Dakota Sandstone and Burro Canyon Formation
US
CS
CL
CL-SC
GR
AP
HIC
Sam
ples
Blo
w C
ount
Wat
er L
evel
REMARKS
20/6
2/6
50/6
Field Engineer : J. Butler
Hole Diameter : 4" Solid
Drilling Method : Continuous Flight Auger
Sampling Method : Mod. California Sampler
Date Drilled : 01/07/2016
Total Depth (approx.) : 2.75 feet
Location : See Figure 1 in Report
LOG OF BORING TB - 15
PN:54077GE
109 W Main Street, Room 302Montezuma County Commissioners
Combined Court BuildingMontezuma County
Depthin
feet
0
1
2
3
DESCRIPTION
Sample Type
Mod. California Sampler
Bag Sample
Standard Split Spoon
Water Level
Water Level During Drilling
Water Level After Drilling
US
CS
GR
AP
HIC
Sam
ples
Blo
w C
ount
Wat
er L
evel
REMARKS
CLAY, sandy, soft, very moist, red
CLAY, sandy, stiff,slightly moist, red
WEATHERED FORMATION, sandstone with claystone, hard
Auger Refusal on FORMATIONAL MATERIAL at two and three-quarter (2.75) feet, sandstone, very hard, slightly moist, tan, Dakota Sandstone and Burro Canyon Formation
CL
CL
Field Engineer : J. Butler
Hole Diameter : 4" Solid
Drilling Method : Continuous Flight Auger
Sampling Method : Mod. California Sampler
Date Drilled : 01/07/2016
Total Depth (approx.) : 5.5 feet
Location : See Figure 1 in Report
LOG OF BORING TB - 16
PN:54077GE
109 W Main Street, Room 302Montezuma County Commissioners
Combined Court BuildingMontezuma County
Depthin
feet
0
1
2
3
4
5
6
DESCRIPTION
Sample Type
Mod. California Sampler
Bag Sample
Standard Split Spoon
Water Level
Water Level During Drilling
Water Level After Drilling
US
CS
GR
AP
HIC
Sam
ples
Blo
w C
ount
Wat
er L
evel
REMARKS
CLAY, sandy, soft, very moist, red
CLAY and SAND, some chemical deposits, stiff to very hard, slightly moist, red and tan
FORMATIONAL MATERIAL at four and one-half feet, sandstone, very hard, slightly moist, tan, Dakota Sandstone and Burro Canyon Formation
Auger Refusal at five and one-half (5.5) feet
CL
CL-SC
LOG OF BORING TB - 17
PN:54077GE
109 W Main Street, Room 302Montezuma County Commissioners
Combined Court BuildingMontezuma County
Depthin
feet
0
1
2
3
4
5
6
7
8
DESCRIPTION
Sample Type
Mod. California Sampler
Bag Sample
Standard Split Spoon
Water Level
Water Level During Drilling
Water Level After Drilling
US
CS
GR
AP
HIC
Sam
ples
Blo
w C
ount
Wat
er L
evel
REMARKS
Field Engineer : J. Butler
Hole Diameter : 4" Solid
Drilling Method : Continuous Flight Auger
Sampling Method : Mod. California Sampler
Date Drilled : 01/07/2016
Total Depth (approx.) : 7 feet
Location : See Figure 1 in Report
CLAY, sandy, soft, very moist, red
CLAY and SAND, chemical deposits, stiff to very stiff, slightly moist, red and tan
WEATHERED FORMATION, sandstone, hard to very hard, tan
Auger Refusal at seven (7) feet
CL
CL-SC
PN: 54077GE
January 28, 2016
APPENDIX B
Laboratory Test Results
Tested By: Checked By:
4.1
(no specification provided)*
PL= LL= PI=
USCS (D 2487)= AASHTO (M 145)=
D90= D85= D60=D50= D30= D15=D10= Cu= Cc=
Remarks
CL - Lean clay with sand
.50.375#4
#10#40#200
10010010010010082
16 28 12
CL A-6(8)
0.1393 0.0925
1-8-16 1-21-16
J. Center
R. Barrett
Engineer Tech.
1-8-16
Montezuma County Commissioners
Montezuma County Combined Courts Building
54077GE
Material Description
Atterberg Limits (ASTM D 4318)
Classification
Coefficients
Date Received: Date Tested:
Tested By:
Checked By:
Title:
Date Sampled:Location: Test Boring 4Sample Number: 11702-D Depth: 0-3 1/2'
Client:
Project:
Project No: Figure
TEST RESULTS
Opening Percent Spec.* Pass?
Size Finer (Percent) (X=Fail)
PE
RC
EN
T F
INE
R
0
10
20
30
40
50
60
70
80
90
100
GRAIN SIZE - mm.
0.0010.010.1110100
% +3" % GravelCoarse
% Sand
Fine Silt
% Fines
Clay
0 0 0 18 82
6 in.
3 in.
2 in.
1½
in.
1 in.
¾ in.
½ in.
3/8
in.
#4
#10
#20
#30
#40
#60
#100
#140
#200
Particle Size Distribution Report
Tested By: Checked By:
4.2
(no specification provided)*
PL= LL= PI=
USCS (D 2487)= AASHTO (M 145)=
D90= D85= D60=D50= D30= D15=D10= Cu= Cc=
Remarks
CL Sandy lean clay
.50.375#4
#10#40#200
1001001001009967
14 27 13
CL A-6(6)
0.2145 0.1660
1-8-16 1-12-16
J. Townsend
R. Barrett
Engineer Tech.
1-8-16
Montezuma County Commissioners
Montezuma County Combined Courts Building
54077GE
Material Description
Atterberg Limits (ASTM D 4318)
Classification
Coefficients
Date Received: Date Tested:
Tested By:
Checked By:
Title:
Date Sampled:Location: Test Boring 6Sample Number: 11702-EE Depth: 4 1/2'- 9 1/2'
Client:
Project:
Project No: Figure
TEST RESULTS
Opening Percent Spec.* Pass?
Size Finer (Percent) (X=Fail)
PE
RC
EN
T F
INE
R
0
10
20
30
40
50
60
70
80
90
100
GRAIN SIZE - mm.
0.0010.010.1110100
% +3" % GravelCoarse
% Sand
Fine Silt
% Fines
Clay
0 0 1 32 67
6 in.
3 in.
2 in.
1½
in.
1 in.
¾ in.
½ in.
3/8
in.
#4
#10
#20
#30
#40
#60
#100
#140
#200
Particle Size Distribution Report
Tested By: Checked By:
4.3
(no specification provided)*
PL= LL= PI=
USCS (D 2487)= AASHTO (M 145)=
D90= D85= D60=D50= D30= D15=D10= Cu= Cc=
Remarks
CL - Sandy lean clay
.50.375#4
#10#40#200
1001001001009963
14 30 16
CL A-6(7)
0.2259 0.1780
1-8-16 1-14-16
J. Center
R. Barrett
Engineer Tech.
1-8-16
Montezuma County Commissioners
Montezuma County Combined Courts Building
54077GE
Material Description
Atterberg Limits (ASTM D 4318)
Classification
Coefficients
Date Received: Date Tested:
Tested By:
Checked By:
Title:
Date Sampled:Location: Test Boring 7Sample Number: 11702-II Depth: 0-3'
Client:
Project:
Project No: Figure
TEST RESULTS
Opening Percent Spec.* Pass?
Size Finer (Percent) (X=Fail)
PE
RC
EN
T F
INE
R
0
10
20
30
40
50
60
70
80
90
100
GRAIN SIZE - mm.
0.0010.010.1110100
% +3" % GravelCoarse
% Sand
Fine Silt
% Fines
Clay
0 0 1 36 63
6 in.
3 in.
2 in.
1½
in.
1 in.
¾ in.
½ in.
3/8
in.
#4
#10
#20
#30
#40
#60
#100
#140
#200
Particle Size Distribution Report
Tested By: Checked By:
4.4
(no specification provided)*
PL= LL= PI=
USCS (D 2487)= AASHTO (M 145)=
D90= D85= D60=D50= D30= D15=D10= Cu= Cc=
Remarks
CL - Lean clay with sand
.50.375#4
#10#40#200
1001001001009974
16 32 16
CL A-6(10)
0.1897 0.1392
1-8-16 1-14-16
J. Center
R. Barrett
Engineer Tech.
1-8-16
Montezuma County Commissioners
Montezuma County Combined Courts Building
54077GE
Material Description
Atterberg Limits (ASTM D 4318)
Classification
Coefficients
Date Received: Date Tested:
Tested By:
Checked By:
Title:
Date Sampled:Location: Test Boring 8Sample Number: 11702-O Depth: 0-3'
Client:
Project:
Project No: Figure
TEST RESULTS
Opening Percent Spec.* Pass?
Size Finer (Percent) (X=Fail)
PE
RC
EN
T F
INE
R
0
10
20
30
40
50
60
70
80
90
100
GRAIN SIZE - mm.
0.0010.010.1110100
% +3" % GravelCoarse
% Sand
Fine Silt
% Fines
Clay
0 0 1 25 74
6 in.
3 in.
2 in.
1½
in.
1 in.
¾ in.
½ in.
3/8
in.
#4
#10
#20
#30
#40
#60
#100
#140
#200
Particle Size Distribution Report
Tested By: Checked By:
4.5
(no specification provided)*
PL= LL= PI=
USCS (D 2487)= AASHTO (M 145)=
D90= D85= D60=D50= D30= D15=D10= Cu= Cc=
Remarks
CL - Sandy lean clay
.50.375#4
#10#40#200
10010010010010052
14 23 9
CL A-4(2)
0.2499 0.2054 0.0931
1-8-16 1-14-16
J. Center
R. Barrett
Engineer Tech.
1-8-16
Montezuma County Commissioners
Montezuma County Combined Courts Building
54077GE
Material Description
Atterberg Limits (ASTM D 4318)
Classification
Coefficients
Date Received: Date Tested:
Tested By:
Checked By:
Title:
Date Sampled:Location: Test Boring 14Sample Number: 11702-U Depth: 5'-9'
Client:
Project:
Project No: Figure
TEST RESULTS
Opening Percent Spec.* Pass?
Size Finer (Percent) (X=Fail)
PE
RC
EN
T F
INE
R
0
10
20
30
40
50
60
70
80
90
100
GRAIN SIZE - mm.
0.0010.010.1110100
% +3" % GravelCoarse
% Sand
Fine Silt
% Fines
Clay
0 0 0 48 52
6 in.
3 in.
2 in.
1½
in.
1 in.
¾ in.
½ in.
3/8
in.
#4
#10
#20
#30
#40
#60
#100
#140
#200
Particle Size Distribution Report
Tested By: Checked By:
4.6
(no specification provided)*
PL= LL= PI=
USCS (D 2487)= AASHTO (M 145)=
D90= D85= D60=D50= D30= D15=D10= Cu= Cc=
Remarks
CL - Sandy lean clay
.50.375#4
#10#40#200
1001001001009960
15 26 11
CL A-6(4)
0.2409 0.1915 0.0754
1-8-16 1-13-16
J. Townsend
R. Barrett
Engineer Tech.
1-8-16
Montezuma County Commissioners
Montezuma County Combined Courts Building
54077GE
Material Description
Atterberg Limits (ASTM D 4318)
Classification
Coefficients
Date Received: Date Tested:
Tested By:
Checked By:
Title:
Date Sampled:Location: BulkSample Number: 11702-X
Client:
Project:
Project No: Figure
TEST RESULTS
Opening Percent Spec.* Pass?
Size Finer (Percent) (X=Fail)
PE
RC
EN
T F
INE
R
0
10
20
30
40
50
60
70
80
90
100
GRAIN SIZE - mm.
0.0010.010.1110100
% +3" % GravelCoarse
% Sand
Fine Silt
% Fines
Clay
0 0 1 39 60
6 in.
3 in.
2 in.
1½
in.
1 in.
¾ in.
½ in.
3/8
in.
#4
#10
#20
#30
#40
#60
#100
#140
#200
Particle Size Distribution Report
Sample Source
Soil Description
Swell Pressure (P.S.F)
Initial Final
Moisture Content (%) 3.3 18.4
Dry Density (P.C.F) 106.3 115.0
Height (in.) 1.000 0.950
Diameter (in.) 1.94 1.94
Project Number
Date
Figure
SWELL - CONSOLIDATION TEST
SUMMARY OF TEST RESULTS
TB-3 at 1.5 feet
4.7
Sandy Clay (CL)
0
54077GE
January 12, 2016
-6
-5
-4
-3
-2
-1
0
10 100 1000 10000
Co
ns
oli
da
tio
n %
Sw
ell
Pressure (Pounds per Square Foot)
Swell/Consolidation due to wetting under constant load
Water added tosample
Sample Source
Soil Description
Swell Pressure (P.S.F)
Initial Final
Moisture Content (%) 7.6 13.3
Dry Density (P.C.F) 128.6 128.3
Height (in.) 1.000 0.979
Diameter (in.) 1.94 1.94
Project Number
Date
Figure
SWELL - CONSOLIDATION TEST
SUMMARY OF TEST RESULTS
TB-4 at 13.5 feet
4.8
Claystone
900
54077GE
January 11, 2016
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
1.5
10 100 1000 10000
Co
ns
oli
da
tio
n %
Sw
ell
Pressure (Pounds per Square Foot)
Swell/Consolidation due to wetting under constant load
Water added tosample
Sample Source
Soil Description
Swell Pressure (P.S.F)
Initial Final
Moisture Content (%) 4.8 16.2
Dry Density (P.C.F) 111.1 120.7
Height (in.) 1.000 0.910
Diameter (in.) 1.94 1.94
Project Number
Date
Figure
SWELL - CONSOLIDATION TEST
SUMMARY OF TEST RESULTS
TB-5 at 2 feet
4.9
Sandy Clay
0
54077GE
January 14, 2016
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
10 100 1000 10000
Co
ns
oli
da
tio
n %
Sw
ell
Pressure (Pounds per Square Foot)
Swell/Consolidation due to wetting under constant load
Water added tosample
Sample Source
Soil Description
Swell Pressure (P.S.F)
Initial Final
Moisture Content (%) 3.6 17.3
Dry Density (P.C.F) 111.4 121.6
Height (in.) 1.000 0.910
Diameter (in.) 1.94 1.94
Project Number
Date
Figure 4.10
SWELL - CONSOLIDATION TEST
SUMMARY OF TEST RESULTS
TB-6 at 4.5 feet
Sandy Clay
290
54077GE
January 12, 2016
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
10 100 1000 10000
Co
ns
oli
da
tio
n %
Sw
ell
Pressure (Pounds per Square Foot)
Swell/Consolidation due to wetting under constant load
Water added tosample
Sample Source
Soil Description
Swell Pressure (P.S.F)
Initial Final
Moisture Content (%) 2.5 16.3
Dry Density (P.C.F) 115.4 120.3
Height (in.) 1.000 0.938
Diameter (in.) 1.94 1.94
Project Number
Date
Figure 4.11
SWELL - CONSOLIDATION TEST
SUMMARY OF TEST RESULTS
TB-8 at 3.5 feet
Sandy Clay
300
54077GE
January 12, 2016
-7
-6
-5
-4
-3
-2
-1
0
10 100 1000 10000
Co
ns
oli
da
tio
n %
Sw
ell
Pressure (Pounds per Square Foot)
Swell/Consolidation due to wetting under constant load
Water added tosample
Sample Source
Soil Description
Swell Pressure (P.S.F)
Initial Final
Moisture Content (%) 7.9 16.3
Dry Density (P.C.F) 118.0 121.0
Height (in.) 1.000 0.962
Diameter (in.) 1.94 1.94
Project Number
Date
Figure 4.12
SWELL - CONSOLIDATION TEST
SUMMARY OF TEST RESULTS
TB-11 at 1 foot
Sandy Clay
950
54077GE
January 12, 2016
-4.5
-4
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
10 100 1000 10000
Co
ns
oli
da
tio
n %
Sw
ell
Pressure (Pounds per Square Foot)
Swell/Consolidation due to wetting under constant load
Water added tosample
Direct Shear Test Results ASTM D3080-90
Project: Montezuma County Courts Visual Soil Description: Sandy Clay
Type of Specimen: Remolded
Laboratory Number: 11702AA Diameter 1.946 in.
Date: 1/15/2016 Thickness 2.0 in
Project Technician: RB Sample Source: TB-5: 3'-8'
Summary of Sample Data:Initial Moisture Content (%) 6.8
Intial Dry Density (P.C.F) 124.3
Final Moisture Content (%) 12.9
Final Dry Density (P.C.F) 124.3
Residual Direct Shear Test Results:Normal Stress (P.S.I) 2.04 4.07 8.15
Max. Shear Stress (P.S.I) 1.73 2.81 5.84
ESTIMATED STRENGTH PARAMETERS
Angle of Internal Friction, phi 32
Cohesion, P.S.F. 50
Figure 4.13
Project Number: 54077GE
0
2
4
6
8
0 2 4 6 8 10
Sh
ear
Str
ess, P
.S.I
.
Normal Stress, P.S.I.
0
1
2
3
4
5
6
7
8
9
10
0.00 0.05 0.10 0.15 0.20
Sh
ear
Ste
ss, P
.S.I
.
Horizontal Deformation, inches
Project No. :
Figure: 4.14
Date:
DR
Y D
EN
SIT
Y (PC
F)
MOISTURE CONTENT (%)
0 5 10 15 20 25 30 3580
85
90
95
100
105
110
115
120
130
135
140
145
2.6
2.7
2.8Zero Air Voids forSpecific Gravity
Project:
Sample Source:
Sample Description:
Test Method:
Maximum Dry Density:
Optimum Moisture Content:
Laboratory Number:
Montezuma County Combined Courts Facility
Bulk
ASTM D1557 Method A
124.1 pcf
11.0%
11702-X
54077GE
1-8-16
125
Sandy Clay (CL)
PROJ NO: 54077GE DATE: 1/8/2016
TECHNICIAN: J.Townsend
LAB NO: 17702-X
1557A Condition: soaked Sample Source: Bulk Subgrade
124.1 PCF Surcharge: 15 Lbs
11.0%
Relative
Compaction Swell (%)
104.4 10.9 84 102.0 20.8 1.7 1.5
110.0 10.9 89 107.4 18.7 1.8 5.4
116.3 10.9 94 112.5 17.5 1.6 9.3
Figure:
Dry
Density
(PCF)
Moisture
Content (%)
Dry Density
(PCF)
Moisture
Content of
Top One (1)
Inch (%)
Pre-Soak After 72 hour Soak
PROJECT NAME: Montezuma Co. Combined Courts Facility
4.15
Optimum Moisure
Content*:
California Bearing Ratio Test Results
ASTM D1883
Proctor Method*:
Max Dry Density*:
CBR (0.100"
penetration)
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
102.0 104.0 106.0 108.0 110.0 112.0 114.0 116.0 118.0
Cali
forn
io B
eari
ng
Rati
o (
CB
R)
Dry Density (PCF)
