GEOTECHNICAL ENGINEERING
DESIGN REPORT For The
Montezuma-Cortez High School Project
Prepared For: Mr. Alex Carter, Superintendent
Montezuma County School District RE-1, and, Mr. Jim Ketter, PE, KPMC
Project Number: 53088GE November 7, 2013
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1.0 REPORT INTRODUCTION ................................................................................................ 2
1.1 Scope of Project ................................................................................................................... 3
2.0 GEOTECHNICAL ENGINEERING STUDY .................................................................... 4
2.1 Geotechnical Engineering Study Scope of Service .............................................................. 4
3.0 FIELD STUDY....................................................................................................................... 6
3.1 Project location ................................................................................................................ 6
3.2 Site Description and Geomorphology.................................................................................. 6
3.3 Subsurface Soil and Water Conditions ................................................................................ 6
3.4 Site Seismic Classification .................................................................................................. 12
4.0 LABORATORY STUDY .................................................................................................... 12
5.0 FOUNDATION RECOMMENDATIONS ........................................................................ 14
5.1 Spread Footings ................................................................................................................. 14
5.2 General Shallow Foundation Considerations ................................................................... 17
5.3 Drilled Piers....................................................................................................................... 17
5.4 Grade Beams...................................................................................................................... 20
6.0 RETAINING STRUCTURES............................................................................................. 20
7.0 SUBSURFACE DRAIN SYSTEM ...................................................................................... 22
8.0 CONCRETE FLATWORK ................................................................................................. 24
8.1 Interior Concrete Slab-on-Grade Floors............................................................................ 24
8.2 Exterior Concrete Flatwork Considerations ...................................................................... 27
8.3 General Concrete Flatwork Comments ............................................................................. 28
9.0 PAVEMENT SECTION THICKNESS DESIGN RECOMMENDATIONS .................. 28
10.0 CONSTRUCTION CONSIDERATIONS ........................................................................ 30
10.1 Fill Placement Recommendations..................................................................................... 31
10.1.1 Embankment Fill on Slopes ....................................................................................... 31
10.1.2 Natural Soil Fill ........................................................................................................ 32
10.1.3 Granular Compacted Structural Fill ......................................................................... 33
10.2 Excavation Considerations ............................................................................................... 34
10.2.1 Excavation Cut Slopes ............................................................................................... 35
10.3 Utility Considerations....................................................................................................... 35
10.4 Landscaping Considerations ............................................................................................ 35
10.5 Soil Sulfate Content, Corrosion Issues ............................................................................. 38
10.6 Radon Issues ..................................................................................................................... 38
11.0 CONSTRUCTION MONITORING AND TESTING .................................................... 38
12.0 CONCLUSIONS AND CONSIDERATIONS ................................................................. 39
FIELD STUDY RESULTS…………………………………………………….……Appendix A
Log of Test Borings
LABORATORY TEST RESULTS……………………………………………….. Appendix B
Swell Consolidation Test Results
Moisture Content/Dry Density (Proctor)
California Baring Ratio Test
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1.0 REPORT INTRODUCTION
This report presents our geotechnical engineering recommendations for the new Montezuma-
Cortez High School Project. Our data report was presented on May 6, 2013. This report was
requested by Mr. Alex Carter, Superintendent, Montezuma School District RE-1, and Mr. Jim
Ketter, PE, KPMC. The field study was completed on June 19, 2013. The laboratory study was
completed on July 12, 2013. This November 7, 2013 report is a re-issue of our July 15, 2013
report with the addition of the subsurface logs and tables from our Phase I 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, and slope
stability considerations. 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 10.0 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
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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
development.
In the interest of developing a concise and brief discussion of the geotechnical engineering
conditions and associated design recommendations this report does not contain significant
tutorial information. The intent of this report is for the architect, structural engineer, contractor
and others that are familiar with design and construction terminology. We are available to
discuss and provide additional explanation for those who are not familiar with the terminology,
as needed.
We have not included significant information from our data report for this project. This
information was utilized, however, as part of the development of the recommendation is within
this report. We included some of the previous discussions from the data report within the text
of this report, where appropriate.
The data used to generate our recommendations are presented throughout this report and in the
attached figures.
1.1 Scope of Project
The project development will include construction of a new high school campus. The
proposed main high school structure is located along the northern, higher elevation, portion of
the project site. Athletic fields, tennis courts and other improvements are proposed for the
southern portion of the project site. The proposed entrance and parking areas are located
primarily in the northwest quadrant of the (approximate) 35 acre site.
The structures will include design and construction of steel reinforced concrete foundations
systems and floors, reinforced masonry (veneer and structural) and retaining walls. The proposed
parking area will most likely be constructed of flexible asphalt concrete pavement. The athletic
field will include a track and playing fields with associated bleachers and infrastructure.
The entire project site will likely include relatively extensive earthwork including excavation
cut of portions of the site and fill placement. We suspect that the earthwork portion of the site
will include mass excavation and fill placement utilizing large earth working equipment such as
scrapers and large compaction equipment.
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2.0 GEOTECHNICAL ENGINEERING STUDY
This section of this report presents the results of our field and laboratory study and our
geotechnical engineering recommendations based on the data obtained.
Our services include a geotechnical engineering study of the subsurface soil and water
conditions for development of this site for the proposed high school structure.
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 twenty-eight (28) test borings on the project site for the data report and
advanced an additional eight (8) test borings on the project site for this portion of our
contribution to this project.
• The field study for the design level report included advancing three (3) NWL core borings
and five (5) continuous flight auger test borings.
• Select NWL core, driven sleeve and bulk soil samples were obtained from the test borings
and returned to our laboratory for testing.
Laboratory Study
• The laboratory testing and analysis of the samples obtained included;
� Moisture content and dry density,
� Estimates of soil and rock strength based on unconfined compressive strength
tests and direct shear strength tests, to help establish a basis for development of
soil bearing capacity and lateral earth pressure values,
� 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, and,
� Sulfate content testing of select soil samples to help assess the potential for
corrosion due to sulfates on Portland cement concrete,
� Moisture content/dry density relationship (Proctor) tests, and,
� California Bearing Ratio (CBR) tests
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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, and,
� Lateral Earth Pressure values for design of retaining structures,
� Flexible asphalt concrete pavement thickness 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,
� Comments for placement and compaction of fill on sloped areas,
� 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 considerations, 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
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3.0 FIELD STUDY
3.1 Project location
The project site is located at the southwest corner of the intersection of Sligo and 3rd Street in
Cortez, Colorado. The project site is located on previously undeveloped property that is located
immediately south of the Cortez Wal-Mart.
3.2 Site Description and Geomorphology
The project site is located on a gently sloping surface with the general inclination of the site
being down to the south with inclination generally flatter than about twenty (20) percent. There
are small intermittent ephemeral drainages on the site. The surface soil consists of eolian (wind
blown) loess deposits. The underlying geologic material is the Dakota Formation which consists
of sandstone and claystone and areas of interbedded sandstone and claystone. There are outcrops
of the Dakota in the northeast section of the property.
We observed evidence of previous excavations near the northwest-central portion of the site and
near the northeast corner of the site. We understand that these excavations may be related to
archeological sites on the property. Other portions of the site have had removal of vegetation,
which may have been related to construction activities associated to the previous Wal-Mart
project construction on the adjacent property located north of the site.
Vegetation on the site consists primarily of sage brush with sparse grass.
3.3 Subsurface Soil and Water Conditions
We advanced three (3) NWL rock core borings within the proposed structure and advanced five
(5) continuous flight auger test borings at the project site in addition to the twenty-eight (28) test
borings that were advanced as part of the geotechnical engineering data report for this site.
We have included the test boring location map from Phase 1 below in Figure 1 for reference. We
have shown the outline of the proposed structure locations that was provided to us with the
locations of the test borings that were advanced as part of this study, below on Figure 2. The logs
of the soils encountered in our test borings are presented in Appendix A.
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Figure 1. Phase 1 Test boring location map from Phase 1 report. Red dots indicate auger test
borings (TB-1). Target symbols represent NQ Test Core locations (TC-1).
TC-1
TC-2
TC-4
TC-3
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Figure 2. Test boring and test core location map for Phase II. TB refers to auger advanced
test borings. TC refers to test cores advanced with NWL rock core. “Ph-II” refers to the design
level Phase two study borings.
TC-2, Ph-II
TB-4, Ph-II
TB-5, Ph-II
TB-7, Ph-II
TB-6, Ph-II
TC-1, Ph-II
TC-3, Ph-II
TB-8, Ph-II
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The figure presented above was prepared using plans provided to us and notes taken during the
field work. The intent of the figure is only to show the approximate test boring locations for
reference purposes only. The test borings were marked with survey lath upon their completion.
We recommend that the project surveyor located and establish the elevations of the ground
surface at each test boring location so that the subsurface information provided can better be
correlated to the proposed building and foundation elevations.
We have tailored our subsurface conditions discussion presented in our data report by
incorporating the information obtained from our June 16-19, 2013 subsurface exploration below.
We encountered about one and one-half (1½) to two and one-half (2½) feet of a loess soil
deposit in our test borings. The upper few inches of this material has more organic content than
deeper layers. The material is essentially very fine sand and silt materials with a minor amount
of clay. Though this material may be considered as generally suitable for site fill and
establishing grade, it is less desirable for use as-is for fill material for support of flatwork and
structural components. Though this material is not “topsoil” in the strict sense, it should be
considered for stockpiling and subsequent use as final surface soils in area of the site where
structural components will not be placed. For estimating and budgeting the amount of the more
organic portion of this soil for final surface vegetative planting material we suggest using
between 6 to 9 inches of depth across most of the project site. There are two (2) areas within the
building foot print and parking area where surface vegetation has been recently stripped, and
therefore the depth of this material is generally less within these areas. The recently stripped
areas are easily identifiable on aerial photographs of the site. The upper 6 to 9 inches of the loess
soil material have organic materials and should therefore be stockpiled for use as surface planting
soil and preparation for landscaping and establishment of surface vegetation after the
construction, if the landscape architect or landscape professional determines that they are suitable
for that use.
We encountered clayey sand in our borings to variable depths. This material ranged from
clayey and silty sand, to clay with lesser amounts of sand. Generally this soil layer may be
considered as existing from about two (2) to five (5) feet below the surface within the test
borings advanced for this study.
We encountered lean clay with sandstone fragments in some of our test borings primarily in the
southwest quadrant of the site as part of the data report study. We did not encounter this material
within the test borings for this study; however we have included the previous discussion since it
is possible that this soil will be encountered in the excavation phase of the project. This material
is somewhat anomalous in that it consists of a lean clay with angular clasts of sandstone and
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actually exists within the formational materials as observed in some of our core borings. It is
very atypical for a soil deposit to exist within a formational materials deposit, however it is
possible if there is a sudden climatic change during the depositional period of the formation. In
this case we suspect that the well indurated soil is a result of short term localized erosion and
subsequent deposition of detritus from areas close to the site. As more normal climatic and
depositional characteristics were re-established, additional deposition of the sandstone materials
occurred. The Molas formation is one such mapped geologic unit in the Four Corners region that
was formed in such a fashion. The Molas formation may be observed in outcroppings and
roadway cuts near the Durango Mountain Report and other locations in the San Juan Mountains,
The swell tests performed on samples of the clay and sandstone clast material included in our
data report indicates that it has a very high to extreme swell pressure and potential when wetted
and may consolidate under high loads. If this material is encountered within areas of the
proposed structure or within areas where structural components for ancillary buildings we
recommend that it be removed, if feasible as part of the site preparation. If the depth is such that
removal is not realistic, mitigative measures will need to be developed based on the nature of the
structure or flatwork being supported by this material.
The site is underlain by the Cretaceous Dakota Sandstone. It should be noted that the name of
this geologic unit is somewhat misleading in that the unit contains more than just sandstone.
Carbonaceous shale, lignite and coal are all found within the Dakota Sandstone unit in the Four
Corners region. The generally hard, cliff-forming quartzitic sandstone exposures of this unit are
noted throughout Colorado, thus the name of the unit reflects these omnipresent sandstone beds.
We have had experience in the Cortez area, including recent exploration within a quarter mile
of this site where the sandstone beds of the Dakota are extremely hard and are suitable for
processing and use as rock products. Mesa Sandstone, a local quarry, utilizes sandstone
materials from the Dakota for production of commercial rock products. Although we did find
relatively hard sandstone layers in our core borings, the relatively thin layers of these hard layers
may reduce the viability for utilization of this material for rock products produced on-site. The
additional core and auger borings conducted for this design level report have confirmed that the
site materials that are potentially suitable for on-site crushing and processing do not have
sufficient lateral or vertical extent to be considered for this type of on-site processing.
We encountered a sandy claystone layer that has a medium dark to buff-green color. This
material was encountered within both Ph-II-TC-3 and the immediately adjacent Ph-II-TB-8 from
about five (5) to fifteen (15) feet below the ground surface. We estimate that the ground surface
elevation at these test borings is nominally 6,157 to 6,158 feet, but should be confirmed. We
understand that the current proposed finished floor elevation is 6,155, therefore the estimated
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spread footing foundation system, if used, will be at nominally 6,152 and within this zone of
weathered sandy claystone material. The sandy claystone material generally consists of thin
(generally less than about one (1) inch thick) layers of friable clayey sandstone, interlaminated
with layers of a sandy claystone. The sandy claystone to claystone layers washed out of our core
barrel at some elevations, and expanded extensively and rapidly in others and became lodged in
our core equipment. Due to the friable and delicate nature of the claystone encountered in Ph-II-
TC-3, we advanced a continuous flight auger test boring (Ph-II-TB-8) immediately adjacent to
this core boring so that we could obtain a driven sample of the material for laboratory testing.
The sample tested, Ph-II-TB-8 @ 9 feet, had a measured swell pressure of approximately 7,620
pounds per square foot with a swell potential of about nine (9) percent under a 100 pound per
square foot surcharge load. The sample obtained from Ph-II-TC-3 @ 9 feet had a measured swell
pressure of bout 2,940 pounds per square foot with a slightly less swell potential of about eight
(8) percent.
The elevations of the two samples discussed above are nominally about two (2) feet below the
estimated footing support elevation discussed above, but are within the zone of influence of the
spread footing elevation. Unlike a soil sample where the measured swell potential will constitute
an estimate of volume increase (and associated uplift) that is directly proportional to the
thickness of material wetted, the interlaminated nature of the material encountered suggests that
the actual volume increase will be proportional only to the percentage of the expansive material
within this layer. It is not possible to accurately estimate the proportion of the expansive material
within this layer throughout the proposed building site, but a cursory estimate is between 50 to 75
percent. We have provided additional discussion of this layer relative to a spread footing
foundation design and associated mitigative concepts in Section 5.0 of this report below.
We did not encounter free subsurface water in our test borings at the time of our field work.
Although we do not feel that it is likely that subsurface water will be encountered during the
project construction, it has been our experience on sites with shallow formational materials that
due to a lack of significant a soil mantle that subsurface water migration and temporary perched
areas of subsurface water may occur as a result of heavy precipitation.
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.
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3.4 Site Seismic Classification
The seismic site class as defined by the 2006 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.
We encountered weathered formational material soils in our test borings at and below the
anticipated footing support elevations. Based on our standard penetration test results at this site
and on laboratory test results of the soils tested we feel that the Site Class as outlined in the 2006
international Building Code, Table 1613.5.2 is Site Class C
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
Atterberg Limits; the plastic limit, liquid limit and plasticity index of some of the soil samples
was determined in general accordance with ASTM D4318
Swell-Consolidation Tests; the one dimensional swell-consolidation potential of some of the
soil samples obtained was determined in general accordance with ASTM D2435. The soil
sample tested is exposed to varying loads and usually the addition of water. The one-
dimensional swell-consolidation response of the soil sample to the loads and/or water is
represented graphically on Figures 4.1 through 4.6.
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A synopsis of some of our laboratory swell-consolidation data for the samples tested is
tabulated below.
Sample
Designation,
PHII Borings
Moisture Content
(percent)
Dry Density
(PCF)
Swell Pressure
(PSF) Swell Potential
(% under 100 psf load)
TB4 @ 2’ 8.0 108.0 1,030 0.5
TB5 @ 2’ 6.2 102.1 510 < 0.5
TB6 @ 7’ 4.2 133.8 1,410 1.0
TB7 @ 4’ 4.9 121.8 1,120 1.0
TB8 @ 9’ 7.5 123.2 7,620 9.2
TC3 @ 9’ 7.8 123.8 2,940 8.0
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. The
results of the laboratory Proctor tests are presented on Figure 4.7.
California Bearing Ratio (CBR) Tests; We assessed the pavement section support characteristics
of select composite soil samples in general accordance with ASTM D1883. The results of the
CBR tests are presented on Figure 4.8.
Unconfined Compressive Strength of Rock Core Samples; the unconfined compressive strength
of select in-situ core samples were performed was obtained in general accordance with ASTM
D2166-06. The tests were performed on NWL Core Samples, approximately 1.875 inch
diameter by approximate four (4) inch long. The results of the unconfined compressive strength
samples are presented below
Sample Designation PHII-TC-2@5’ PHII-TC-2@7’
Sample Density (PCF) 134.9 148.7
Unconfined Compressive
Strength (PSI) 2,920 3,880
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Soluble Sulfate Tests: We performed soluble sulfate tests on soil samples obtained during our
field work. The soluble sulfate tests indicate100 parts per million soluble sulfates in the samples
tested. Soluble sulfate considerations are discussed in Section 10.6 of this report.
5.0 FOUNDATION RECOMMENDATIONS
We have provided recommendations for both conventional spread footings and drilled piers
below. Generally we feel that conventional spread footings are a viable foundation system for
the proposed structure based on our subsurface exploration and laboratory testing, however as
discussed in Section 3.3 above, the sandy claystone layer encountered in Ph-II-TC-3 and Ph-
II_TB-8 was determined to have expansive layers, therefore we have provided drilled piers as an
alternative foundation system design for consideration.
5.1 Spread Footings
Generally we encountered materials with a low swell potential in our test borings as shown in
the tabulation presented in Section 4.0 above. We encountered a sandy claystone with a high
swell pressure and swell potential in Ph-II-TC-3 and Ph-II-TB-8. It is not possible to fully
mitigate the potential for uplift of soils with swell pressures on the order of 2,940 to 7,620
pounds per square foot with swell potentials of 8 to 9 percent solely by developing a footing with
a high dead load, since it is not realistic to achieve a design dead load of these magnitudes. The
mitigation of the influence for these swelling soils should include the following;
� Our geotechnical engineer must observe the characteristics of the materials exposed in the
excavation.
� If non-expansive material are encountered the footings may be placed either on the clean,
competent formational material or on a leveling course of compacted granular fill placed
on the competent formational material.
� If the material exposed in the foundation excavation (or portions thereof) is suspected of
being the expansive claystone the following options may be considered:
� Fully excavate expansive materials, if feasible, and support footings on deeper
sandstone,
� If two (2) feet of excavation occurs and expansive materials are still encountered,
compacted structural fill composed of CDOT Class 6, ¾ inch minus aggregate
base course should be placed and compacted as discussed in Section 10 of this
report.
� CDOT Class 6 specifies a range of 3-12 percent passing the #200. For the
purposes of this project the minimum amount passing the #200 sieve should be 6
percent
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It may not be fully possible to identify all expansive layers within the zone of influence below
the footing particularly since the material can only be observed at the bottom of the excavations
at the time of construction, therefore it is imperative that this project include an aggressive effort
to prevent the support material from being wetted after construction. We recommend that a
subsurface drain system be placed around the perimeter footings and adjacent to any areas that
may be influenced by future water leaks in the structure. The subsurface drain system should be
underlain by a 40 mil PVC impervious geotextile material to further reduce the potential for
subsurface water migration as shown below.
It should be noted that based on our understanding if the current finished elevations of 6,155
and the minimum depth required for frost depth that the nominal footing support elevation will
be about 6,152. Based on the topographic map provided that shows the building location,
portions of the building will be located in areas where the current ground surface elevation is
about 6,148. Due to the variable surface topography and the location of the building it will be
necessary to adjust the footing support elevation in portion of the building so that all footings are
either supported directly by the competent sandstone formation, or a layer of structural fill placed
on the formational material.
Compacted backfill of
foundation excavation
Exterior grade sloped to
promote surface drainage
Impervious geotextile
liner, 40 mil PVC or
similar
Subsurface drain –
discussed in Section 7.0
of this report
Landscape drain
discussed din Section
10.5 of this report
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All footings should have a minimum depth of embedment of at least one (1) foot. The
embedment concept is shown below.
The footings may be supported directly by the clean, competent formational material or on a
blanket of compacted structural fill which is supported by the formational material. Footings
supported directly on the formational material may be designed using a bearing capacity of 5,000
pounds per square foot. Footings supported by a blanket of compacted structural fill placed on
the formational material may be designed using a soil bearing capacity of 3,000 pounds per
square foot with a minimum depth of embedment of at least one (1) foot. The bearing capacity
may be increased by twenty (20) percent due to transient loads.
We estimate that the footings designed and constructed above will have a total post construction
settlement of about 1/4 - 1/3 inch. We estimate that the differential settlement may be about ¼
inch.
All footings should be support at an elevation deeper than the maximum depth of frost
penetration for the area. It is our understanding that the current building code for Cortez includes
a minimum depth for frost protection of thirty-six (36) inches. This recommendation includes
exterior isolated footings and column supports. Please contact the local building department for
specific frost depth requirements.
Minimum depth
of embedment Footing
Footing Embedment Concept
No Scale
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The post construction differential settlement may be limited and 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.
5.2 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.
5.3 Drilled Piers
Drilled piers which are designed as end bearing and supported by the clean competent
unweathered formational material underlying the site are a viable foundation system option. The
drilled pier borings should be advanced a minimum of two (2) pier diameters into the hard
sandstone formational material which we anticipate will be encountered at a nominal depth of
about ten (10) to fifteen (15) feet below finished floor elevation, however the elevation of this
material encountered in our test borings ranged from at the ground surface to depths of fifteen
(15) feet, therefore we suspect that the depth encountered during construction will be highly
variable.
If refusal of the equipment occurs prior to establishing the appropriate embedment of the
bottom of the pier into the formational material it may be necessary for the pier drilling
contractor to establish the best type of cutting head for maximum advancement of the pier into
the formational material. Drilled piers supported by the clean, competent formational material
may be designed using a bearing capacity of 30,000 pounds per square foot. The portion of the
pier in the unweathered formational material may be designed using a side friction of 2,000
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pounds per square foot. The drilled piers should be designed to resist uplift associated with
swelling of the support soils. The top of the piers should not be flared, which can allow the soils
to “grab” the pier and cause uplift. Our experience has been that the claystone and shale
formational material in the area may exert swell pressures in the range of about 4,000 to 6,000
pounds per square foot.
The site sandy claystone had a measured swell pressure of as high as about 7,220 pounds per
square foot with a swell potential of about 9.2 percent under a 100 pound per square foot
surcharge load. The swelling soils will tend to grab the piers which will cause tensional forces to
develop in the drilled pier. The total uplift force imposed on the drilled piers by the swelling
sandy claystone may be estimated based on the surface area of the pier that is exposed to the
active depth of the swelling soils. We estimate that the site soils may imposed an uplift force of
about 3,500 pounds per square foot of pier circumference surface area for portion of each pier
where the sandy claystone is encountered. For estimating purposes we suggest that about ten
(10) feet of each pier be considered as being exposed to this uplift force where the claystone is
encountered.
The required depth of the drilled piers to resist movement must be determined to help resist
uplift of the piers from the swelling soils. The required depth of the piers to resist movement is
estimated based on; the soil characteristics and active zone depth, loads from the structure that
will be exerted on the piers, and the diameter of the piers used on the site. We are available to
provide recommendations for minimum pier depths based on the parameters above. We will
need estimates of the imposed structure loads and the chosen pier diameters to perform our
drilled pier depth analysis. Please contact us with this information when it becomes available.
Many geotechnical engineers feel that some mobilization and movement of the pier may be
needed to develop side shear strength and associated skin friction within the soil mantle which
overlies the formational material. Mobilization of the pier can only develop if settlement or
failure of the support materials of the pier occurs. Movement of pier is obviously undesirable
regardless of the mode of movement. If it is desirable to establish design values for additional
side friction from the portion of the piers in the soil mantle, we should be contacted to discuss
this topic and provide additional information, if needed.
The piers should be installed using drilling equipment which is good working order and intended
for advancing large diameter borings. Proper performance of the drilled piers requires
appropriate drilling and installation techniques. All drilled piers must be installed by a contractor
who is familiar with pier construction. The piers should be cased, as required by the site soil
conditions so that no flares or “mushrooms” exist at the tops of the piers. Flares allow for
increased uplift forces to develop in the piers and subsequent movement which may cause
damage to the structure.
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Proper performance of the drilled pier is partially influenced by the character and quality of the
concrete used to construct the pier. The pier concrete should not be too stiff, which may prevent
proper consolidation of the concrete, or too fluid, which may adversely effect the strength of the
concrete. Generally the concrete should have a slump between about three (3) to six (6) inches.
It may be necessary to use mid- or high-range water reducing concrete admixtures to obtain
concrete with both a suitable slump and acceptable concrete compressive strength characteristics.
We generally recommend use of a tremmie and/or pumping equipment should be used to place
concrete in drilled pier borings deeper than about ten (10) feet, however recent studies have
shown that the characteristics of the concrete dropped to this and greater heights has not been
significantly influenced, therefore the structural engineer should be consulted in regard to use of
tremmie, or pump-placed concrete for this project.
We did not encounter free subsurface water in our test borings at the time of our field work. It
has been our experience that subsurface water is often encountered along fractures, fissures and
joints within the formational material. Occasionally the drilling operations will increase the pore
pressures within the adjacent material to produce a small amount of water access to the drilled
pier excavation. If water and/or caving soils are encountered during the pier installation
operation it may be necessary to dewater the pier excavations and remove any caved soils. Pier
concrete should not be conventionally placed if more than a few inches of water exists in the
bottom of the pier boring. If more than a few inches of water exists in the bottom of the boring
the concrete should be placed using a tremmie, or pump, so that the concrete displaces any water
during the pier foundation construction operation.
The support elevation of the pier must be thoroughly cleaned prior to placement of the pier
concrete. Loose material in the bottom of the pier borings will cause settlement of the pier. The
pier support elevation may be cleaned using clean-out tools attached to the drill rig, hand
equipment, excavation suction equipment, or a combination of these. Under no circumstances
should the pier foundation concrete be placed when loose material exists in the bottom of the
borings.
The interface between the weathered formational and the underlying competent formational
material was relatively obscure in some of our test borings and was a transitional contact in other
borings. We should be contacted during construction to aid in determining the appropriate pier
support elevation.
We should be contacted to measure the depth of the piers, verify the competency of the support
materials, and check the plumbness of the piers. We are available provide an as-built record of
the installed drilled pier foundation system. Please contact us if this service is desired.
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5.4 Grade Beams
Grade beams are utilized in a pier and grade beam foundation system to distribute the structure
loads to each of the piers. The grade beam reinforcement and associated span distance is
developed by the project structural engineer. The structural considerations of the grade beam in
association with an assessment of the structure being supported by them will, in part determine
the spacing between each of the deep foundation components, such as drilled piers (or drilled
shafts), helical piers, micropiles and driven piles. Regardless of the type of deep foundation
being considered, it is imperative that an appropriate void be developed below the grade beam so
that swelling soils do not create uplift of the supported structure.
Voids are most commonly developed with commercially available cardboard “void forms” that
are placed at the bottom of the concrete forms prior to placement of reinforcement steel and the
grade beam concrete. If the soils below the grade beam become moistened and expand, the
cardboard void form will collapse without the soils having the ability to impose uplift forces on
the bottom of the grade beam. The height of the void is often related to the expansion potential
of the site soils and anticipated depth of wetting that will develop within the soils below the
grade beam. We generally recommend that a minimum of four (4) inches of void be established.
Thicker voids, such as six (6) inches are common in the areas where more expansive soils are
encountered. We recommend that minimum void height of six (6) inches established for this
project.
We are available to provide additional information in regard to void forms and associated
conditions if additional information is needed.
6.0 RETAINING STRUCTURES
We understand that laterally loaded walls will be constructed as part of this site development.
Lateral loads will be imposed on the retaining structures by the adjacent soils and, in some cases,
surcharge loads on the retained soils. The loads imposed by the soil are commonly referred to as
lateral earth pressures. 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.
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The retaining structures may be designed using the values tabulated below.
Lateral Earth Pressure Values
Type of Lateral Earth Pressure Level Non-Expansive Native
Soil Backfill
(pounds per cubic foot/foot)*
Level Granular Soil Backfill
(pounds per cubic foot/foot)
Active 50 35
At-rest 70 55
Passive 295 460
Allowable Coefficient of Friction 0.31 0.45
Some of the site soils have measured swell pressures of nominally 500 to 1,000 pounds per
square foot which may be exerted on the retaining wall should the backfill soils become
moistened. If the site clay soils are used as backfill they must be moisture conditioned to above
optimum moisture content during the backfill placement. We should be consulted during
construction to verify the characteristics of any native soil backfill for walls taller than five (5)
feet.
The granular soil that is used for the retaining wall backfill may be permeable and may allow
water migration to the foundation support soils. There are several options available to help
reduce water migration to the foundation soils, two of which are discussed here. An impervious
geotextile layer and shallow drain system may be incorporated into the backfill, as discussed in
Section 9.5, Landscaping Considerations, below. A second option is to place a geotextile filter
material on top of the granular soils and above that place about one and one-half (1½) to two (2)
feet of moisture conditioned and compacted site clay soils. It should be noted that if the site clay
soils are used volume changes may occur which will influence the performance of overlying
concrete flatwork or structural components.
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, if these soils are available.
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 and/or weep holes should be included in the retaining structure
design. Exterior retaining structures may be constructed with weep holes to allow subsurface
water migration through the retaining structures. A drain system constructed with a free draining
aggregate material and a perforated pipe should be constructed adjacent to retaining structures or
adjacent to foundation walls on sites with expansive soil conditions. 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.
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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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 or a sump vault. 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 the basement or crawl space areas. 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 within
the proposed basements. We suggest that the utility trench backfill be thoroughly compacted to
help reduce the amount of water migration. The subsurface drain system should be designed to
collect subsurface water from the utility trench and fractures within the formational material and
direct it to surface discharge points.
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 uplift from swelling soils and/or frost heave. It is prudent for the design
and construction of concrete flatwork on this project to be able to accommodate some movement
associated with swelling soil conditions, if possible.
The soil samples tested have a measured swell pressure of 500 to 1,000 pounds per square foot
and a negligible volume increase under a 100 pound per square foot surcharge load. The
formational sandy claystone has swell pressures of as high as 7,620, however based on the
locations and elevations where the formational sandy claystone was encountered we suspect that
this expansive layer will not be encountered at the slab-on-grade support elevations throughout
the site. As with the footing support considerations we have provided an outline regarding
observations of the slab-support materials with associated recommended actions in the following
section of this report.
8.1 Interior Concrete Slab-on-Grade Floors
Generally the interior floor support materials will be less susceptible to water intrusion and
subsequent moisture migration, however care should be taken during the construction operations
to verify that the sandy claystone with expansive characteristics does not exist in support areas
for interior floors. If the expansive claystone is encountered under portions of the floor slab we
recommend that the following be conducted, which is the same outline as presented in Section
5.1, above.
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� Our geotechnical engineer must observe the characteristics of the materials exposed in the
excavation.
� If non-expansive material are encountered the footings may be placed either on the clean,
competent formational material or on a leveling course of compacted granular fill placed
on the competent formational material.
� If the material exposed in the foundation excavation (or portions thereof) is suspected of
being the expansive claystone the following options may be considered:
� Fully excavate expansive materials, if feasible, and support footings on deeper
sandstone,
� If two (2) feet of excavation occurs and expansive materials are still encountered,
compacted structural fill composed of CDOT Class 6, ¾ inch minus aggregate
base course should be placed and compacted as discussed in Section 10 of this
report.
� CDOT Class 6 specifies a range of 3-12 percent passing the #200. For the
purposes of this project the minimum amount passing the #200 sieve should be 6
percent
Regardless of support materials encountered on this site we recommend that they be supported
by a one (1) foot thick layer of compacted structural fill. This will help mitigate soils or other
materials that have a lesser swell potential than the claystone materials discussed throughout this
report.
If drilled piers are utilized for this project, it may be desirable to structurally support the floor
slabs to take full advantage of the more robust drilled pier foundation design. 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 swelling soils on the performance of the
concrete slab-on-grade floors.
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.
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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
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 fine-grained granular
material, such as crusher reject material to protect it from punctures from the underlying
substrate materials with at least four (4) 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 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 granular materials utilized for vapor or capillary considerations may be
considered as contributing to the compacted structural fill thickness discussed above. 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.
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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
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, particularly on sites with high silt-content soils. Without complete removal of soils
susceptible to frost heave, all exterior flatwork will be exposed to some potential for frost heave.
Since there is no subsurface water on the project site, any frost heave that occurs will be
associated with precipitation, snow melt, or irrigation. Proper surface drainage and eliminating
areas near exterior concrete flatwork where water may pond will greatly reduce the potential for
frost heave.
For exterior concrete flatwork that is placed immediately adjacent to the structure or other
critical structural components it is prudent to consider a thick granular compacted structural fill
layer of about two (2) feet and to isolate this flatwork from the structure or exterior finishes to
that uplift associated with frost heave does not influence exterior components or veneer.
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 six (6) to eight (8)
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.
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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.
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 15 in our
analysis for the pavement section thickness design.
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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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 twelve (12)
inches, moisture conditioned and compacted prior to placement of the overlying aggregate
pavement 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 asphalt 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.
We recommend that the asphalt concrete used on this project be mixed in accordance with a
design prepared by a licensed professional engineer, or a 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 and 75,000 - 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
50,000 18k ESAL
Pavement Section Component Alternative Thicknesses of Each Component
(inches)
Asphalt Concrete 3 3 3 4 6
Class 6 4 6 10 6 0
Class 2 8 5 0 0 0
Reconditioned Subgrade 12 12 12 12 12
Pavement Section Design Thickness
75,000 18k ESAL
Pavement Section Component Alternative Thicknesses of Each Component
(inches)
Asphalt Concrete 3 3 3 4 4 5 6.5
Class 6 4 6 11 4 8 5 0
Class 2 10 7 0 5 0 0 0
Reconditioned Subgrade 12 12 12 12 12 12 12
The pavement section thicknesses tabulated above are appropriate for the post-construction
residential traffic use. 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 a partial section be constructed followed by construction of an overlay after
completion of the construction operations. We are available to discuss this with you as the
project progresses.
10.0 CONSTRUCTION CONSIDERATIONS
This section of the report provides more tutorial information than previous section and includes
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.
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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.
We observed evidence of previous site use and excavations associated with archeological sites.
We suspect that man-placed fill or subsurface disturbance may be encountered as the project
construction progresses. All existing fill material should be removed from areas planned for
support of structural components. Excavated areas and subterranean voids should be backfilled
with properly compacted fill material as discussed below.
10.1.1 Embankment Fill on Slopes
Embankment fill placed on slopes must be placed in areas that have been properly prepared
prior to placement of the fill material. The fill should be placed in a toe key and benches
constructed into the slope. The concept is shown below.
New Embankment Fill
Bench Drain-
optional, as needed
Toe Key Drain, optional,
as needed
Benches
Toe Key
Pre-construction ground
surface
Toe Key and Bench Concept No Scale
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The width of the toe key should be at least one-fourth (1/4) of the height of the fill. The
elevation difference between each bench, width, and geometry of each bench is not critical,
but generally the elevation difference between each lift should not exceed about three (3) to four
(4) feet. The benches should be of sufficient width to allow for placement of horizontal lifts of
fill material, therefore the size of the compaction equipment used will influence the bench
widths.
Embankment fill material thicker than five (5) feet should be analyzed on a site specific basis.
The fill mass may impose significant loads on, and influence the stability of the underlying slope.
We suggest that no fill slopes steeper than two and one-half to one (2½:1, horizontal to vertical)
be constructed unless a slope stability analysis of the site is conducted.
The toe key and bench drains shown above should be placed to reduce the potential for water
accumulation in the embankment fill and in the soils adjacent to the embankment fill. The
placement of these drains is more critical on larger fill areas, areas where subsurface water exists
and in areas where the slopes are marginally stable.
The toe key and bench drains may consist of a perforated pipe which is surrounded by a free
draining material which is wrapped by a geotextile filter fabric. The pipe should be surrounded
by four (4) to six (6) cubic feet of free draining material per lineal foot of drain pipe.
10.1.2 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.
Due to the expansive characteristics of the natural soil encountered on portions of the site,
particularly during the data report preparation, we recommend that any native soil proposed for
use as fill be evaluated during the construction operation to determine the suitability of specific
soil for use as fill within areas where structural components will be placed. All natural soils may
be used to establish general site elevation where not structural components or other improvement
features are constructed.
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
PN: 53088GE Design Level Geotechnical Engineering Report
November 7, 2013
33
minor amount of surface moisture develops on the cast, the material is close to the desired
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.
10.1.3 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 modification to the CDOT Specifications for
Class 6 material, in regard to the minimum recommended percent passing the #200 sieve below
PN: 53088GE Design Level Geotechnical Engineering Report
November 7, 2013
34
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 6 – 15
* Modified from CDOT Specifications in regard to -#200 specifications.
Liquid Limit of this material should be less than 30
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.
Clean crushed aggregate fill should not be used on this project site due to the potentially
expansive nature of some of the materials that may be encountered below the footing support
elevations.
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 are 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. If water is encountered during
construction, it may be necessary to dewater excavations to provide for suitable working
conditions.
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.
PN: 53088GE Design Level Geotechnical Engineering Report
November 7, 2013
35
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.
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.
We did not observe evidence of existing unstable slope areas influencing the site, but due to the
steepness and extent of the slopes in the area we suggest that the magnitude of the proposed
excavation slopes be minimized and/or supported by retaining structures.
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.
10.4 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.
PN: 53088GE Design Level Geotechnical Engineering Report
November 7, 2013
36
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: 53088GE Design Level Geotechnical Engineering Report
November 7, 2013
37
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.
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: 53088GE Design Level Geotechnical Engineering Report
November 7, 2013
38
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.
The landscape drain system concept provided above as an additional mitigative effort in the
event that spread footings are use to support the structure We are available to help tailor this
concept as needed to best suit the needs of this project. Often this concept is implemented only
on the northern sides of structures and/or where snow may accumulate and melt water may
migrate toward subsurface areas under the structure.
10.5 Soil Sulfate Content, Corrosion Issues
We performed soluble sulfate content tests on select soil samples obtained during our field
study. The soluble sulfate content was 100 parts per million. The American Concrete Institute
(ACI) indicates that soil with a soluble sulfate content of 100 parts per million constitutes a
negligible exposure of sulfate corrosion to concrete.
The ACI does not provide specific design or concrete constituent recommendations for
concrete exposed to soil with a negligible corrosion potential.
10.6 Radon Issues
The requested scope of service of this report did not include assessment of the site soils for
radon production. We have provided radon test results separately from this report.
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
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.
PN: 53088GE Design Level Geotechnical Engineering Report
November 7, 2013
39
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.
PN: 53088GE Design Level Geotechnical Engineering Report
November 7, 2013
40
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.
Please contact us if you have any questions, or if we may be of additional service.
Respectfully submitted, TRAUTNER GEOTECHTRAUTNER GEOTECHTRAUTNER GEOTECHTRAUTNER GEOTECH LLC LLC LLC LLC
David L. Trautner, P.E., CPG
Principal Geotechnical Engineer
PN: 53088GE May 6, 2013
APPENDIX A
Field Study Results
07-1
2-20
13 T
:\Cur
rent
GE
\530
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5308
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. II,
TC-1
.bor
Field Engineer : J. ButlerHole Diameter : NQDrilling Method : Wireline CoreSampling Method : NQ CoreDate Drilled : June 16, 2013Total Depth : 22 feetLocation : See Figure in Report
LOG OF BORING PH. II, TC-1
PN: 53088GEMr. Jim Ketter, PE, KPMC
Mr. Alex Carter, SuperintendentPhase II , Design Level
Montezuma-Cortez High School
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.
Clay, sandy, medium stiff, slightly moist to moist, tan to red (CL)
WEATHERED FORMATIONAL MATERIAL, Dakota Sandstone Formation, weathered sandstone with thin interbedded layers of clayey sandstone, highly fractured, stiff/hard, tan to white
CLAYEY SANDSTONE, highly fractured
SANDSTONE, highly fractured, white
Bottom of test core run at twenty-two (22) feet
CL
Top of First Run at four and one-half (4.5) 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.= 0%
Bottom of Second Run at twelve (12) feet Top of Third Run at twelve (12) feet
Recovery= 100%R.Q.D.= 0%
Bottom of Third Run at seventeen (17) feetTop of Fourth Run at seventeen (17) feet
Recovery=100%R.Q.D.= 15%
Bottom of Fourth Run at twenty-two (22) feet
07-1
2-20
13 T
:\Cur
rent
GE
\530
04G
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GE\
5308
8GE,
MC
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Mon
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Hig
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\PH
ASE
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CH
S PH
. II,
TC-2
.bor
Field Engineer : J. ButlerHole Diameter : NQDrilling Method : Wireline CoreSampling Method : NQ CoreDate Drilled : June 18, 2013Total Depth : 22 feetLocation : See Figure in Report
LOG OF BORING PH. II, TC-2
PN: 53088GEMr. Jim Ketter, PE, KPMC
Mr. Alex Carter, SuperintendentPhase II , Design Level
Montezuma-Cortez High School
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 four (4) feet
Recovery= 100% R.Q.D= 60%
Bottom of First Run at seven (7) feetTop of Second Run at seven (7) feet
Recovery= 100%R.Q.D.= 71%
Bottom of Second Run at twelve (12) feet Top of Third Run at twelve (12) feet
Recovery= 100%R.Q.D.= 9%
Bottom of Third Run at seventeen (17) feetTop of Fourth Run at seventeen (17) feet
Recovery=100%R.Q.D.= 31%
Bottom of Fourth Run at twenty-two (22) feet
Clay, sandy, medium stiff, slightly moist, red (CL)
FORMATIONAL MATERIAL, Dakota Sandstone Formation, sandstone, white to tan, moderate to low fracturing, black layer at five (5) to six (6) feet
SANDSTONE, white to tan, highly fractured
Bottom of test core run at twenty-two (22) feet
CL
07-1
2-20
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:\Cur
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GE
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GE\
5308
8GE,
MC
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Mon
tezu
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CH
S PH
. II,
TC-3
.bor
Field Engineer : J. ButlerHole Diameter : NQDrilling Method : Wireline CoreSampling Method : NQ CoreDate Drilled : June 18, 2013Total Depth : 16 feetLocation : See Figure in Report
LOG OF BORING PH. II, TC-3
PN: 53088GEMr. Jim Ketter, PE, KPMC
Mr. Alex Carter, SuperintendentPhase II , Design Level
Montezuma-Cortez High School
Depthin
feet
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
DESCRIPTION
NQ Core
Clay, sandy, medium stiff, slightly moist, red (CL)
WEATHERED FORMATIONAL MATERIAL, Dakota Sandstone Formation, sandstone layer at five (5) to five and one-half (5.5) feet, sandy claystone, white to tan, highly fractured
SANDSTONE, white to tan, fractured
Bottom of test core run at sixteen (16) feet
US
CS
CL
GR
AP
HIC
Run
dep
th
Recovery and R.Q.D.
Top of First Run at three and one-half (3.5) feet
Recovery= 12% R.Q.D= 0%
Bottom of First Run at seven (7) feetTop of Second Run at seven (7) feet
Recovery= 100%R.Q.D.= 0%
Bottom of Second Run at twelve (12) feet Top of Third Run at twelve (12) feet
Core water washed coreNo recovery
Bottom of Third Run at sixteen (16) feet
07-1
2-20
13 T
:\Cur
rent
GE
\530
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3096
GE\
5308
8GE,
MC
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Mon
tezu
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tez
Hig
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\PH
ASE
II Te
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orin
g Lo
gs\M
CH
S PH
. II,
TB-4
.bor
Field Engineer : J. ButlerHole Diameter : 4" solidDrilling Method : Continuous Flight AugerSampling Method : Mod. California SamplerDate Drilled : 06/19/2013Total Depth (approx.) : 6.5 feetLocation : See Figure in Report
LOG OF BORING PH. II TB-4
PN:53088GEMr. Jim Ketter, PE, KPMC
Mr. Alex Carter, SuperintendentPhase II, Design Level
Montezuma-Cortez High School
Depthin
feet
0
1
2
3
4
5
6
7
8
DESCRIPTION
Sample TypeMod. California Sampler
Bag Sample
Standard Split Spoon
Water LevelWater Level During Drilling
Water Level After Drilling
CLAY, sandy, medium stiff, dry, red
CLAY, sandy, very stiff, slightly moist, red to white, white chemical deposits
WEATHERED FORMATIONAL MATERIAL, Dakota Sandstone Formation, sandy claystone, hard/stiff, slightly moist, tan
SANDSTONE, very hard, slightly moist, tan
Auger refusal at six and one-half (6.5) feet
US
CS
CL
CL
GR
AP
HIC
Sam
ples
Blo
w C
ount
Wat
er L
evel
REMARKS
18/6
50/5
17/6
19/6
22/6
07-1
2-20
13 T
:\Cur
rent
GE
\530
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3096
GE\
5308
8GE,
MC
HS
Mon
tezu
ma
Cor
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Hig
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\PH
ASE
II Te
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orin
g Lo
gs\M
CH
S PH
. II,
TB-5
.bor
Field Engineer : J. ButlerHole Diameter : 4" solidDrilling Method : Continuous Flight AugerSampling Method : Mod. California SamplerDate Drilled : 06/19/2013Total Depth (approx.) : 12 feetLocation : See Figure in Report
LOG OF BORING PH. II TB-5
PN:53088GEMr. Jim Ketter, PE, KPMC
Mr. Alex Carter, SuperintendentPhase II, Design Level
Montezuma-Cortez High School
Depthin
feet
0
1
2
3
4
5
6
7
8
9
10
11
12
13
DESCRIPTION
Sample TypeMod. California Sampler
Bag Sample
Standard Split Spoon
Water LevelWater Level During Drilling
Water Level After Drilling
CLAY, sandy, medium stiff, dry, red
WEATHERED FORMATIONAL MATERIAL, Dakota Sandstone Formation, sandy claystone, hard/stiff, moist, tan, very hard sandstone layer at six and one-half (6.5) feet to eight (8) feet
Auger refusal at twelve (12) feet
US
CS
CL
GR
AP
HIC
Sam
ples
Blo
w C
ount
Wat
er L
evel
REMARKS
10/6
10/5
50/6
07-1
2-20
13 T
:\Cur
rent
GE
\530
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3096
GE\
5308
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MC
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tezu
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Cor
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Hig
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\PH
ASE
II Te
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orin
g Lo
gs\M
CH
S PH
. II,
TB-5
.bor
Field Engineer : J. ButlerHole Diameter : 4" solidDrilling Method : Continuous Flight AugerSampling Method : Mod. California SamplerDate Drilled : 06/19/2013Total Depth (approx.) : 12 feetLocation : See Figure in Report
LOG OF BORING PH. II TB-6
PN:53088GEMr. Jim Ketter, PE, KPMC
Mr. Alex Carter, SuperintendentPhase II, Design Level
Montezuma-Cortez High School
Depthin
feet
0
1
2
3
4
5
6
7
8
9
10
11
12
13
DESCRIPTION
Sample TypeMod. California Sampler
Bag Sample
Standard Split Spoon
Water LevelWater 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, medium stiff, moist, red
FORMATIONAL MATERIAL, Dakota Sandstone Formation, sandstone, very hard, white to tan
SANDY CLAYSTONE, hard to very hard, thin interbedded sandstone lenses
SANDSTONE, very hard, white to tan
Auger refusal at twelve (12) feet
CL
12/6
50/4
23/6
50/5
07-1
2-20
13 T
:\Cur
rent
GE
\530
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E th
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3096
GE\
5308
8GE,
MC
HS
Mon
tezu
ma
Cor
tez
Hig
h Sc
hool
\PH
ASE
II Te
st B
orin
g Lo
gs\M
CH
S PH
. II,
TB-7
.bor
Field Engineer : J. ButlerHole Diameter : 4" solidDrilling Method : Continuous Flight AugerSampling Method : Mod. California SamplerDate Drilled : 06/19/2013Total Depth (approx.) : 14 feetLocation : See Figure in Report
LOG OF BORING PH. II TB-7
PN:53088GEMr. Jim Ketter, PE, KPMC
Mr. Alex Carter, SuperintendentPhase II, Design Level
Montezuma-Cortez High School
Depthin
feet
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
DESCRIPTION
Sample TypeMod. California Sampler
Bag Sample
Standard Split Spoon
Water LevelWater Level During Drilling
Water Level After Drilling
CLAY, sandy, medium stiff, dry, red
WEATHERED FORMATIONAL MATERIAL, Dakota Sandstone Formation, sandy claystone, hard/stiff, slightly moist, white to gray
CLAYEY SANDSTONE, hard to very hard, slightly moist, tan
Auger refusal at fourteen (14) feet
US
CS
CL
GR
AP
HIC
Sam
ples
Blo
w C
ount
Wat
er L
evel
REMARKS
14/6
50/5
12/6
50/4
07-1
2-20
13 T
:\Cur
rent
GE
\530
04G
E th
ru 5
3096
GE\
5308
8GE,
MC
HS
Mon
tezu
ma
Cor
tez
Hig
h Sc
hool
\PH
ASE
II Te
st B
orin
g Lo
gs\M
CH
S PH
. II,
TB-8
.bor
Field Engineer : J. ButlerHole Diameter : 4" solidDrilling Method : Continuous Flight AugerSampling Method : Mod. California SamplerDate Drilled : 06/19/2013Total Depth (approx.) : 14 feetLocation : See Figure in Report
LOG OF BORING PH. II TB-8
PN:53088GEMr. Jim Ketter, PE, KPMC
Mr. Alex Carter, SuperintendentPhase II, Design Level
Montezuma-Cortez High School
Depthin
feet
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
DESCRIPTION
Sample TypeMod. California Sampler
Bag Sample
Standard Split Spoon
Water LevelWater Level During Drilling
Water Level After Drilling
CLAY, sandy, medium stiff, slightly moist, red
CLAY, sandy, medium stiff, moist, tan
FORMATIONAL MATERIAL, Dakota Sandstone Formation, sandstone, very hard, white
SANDY CLAYSTONE, interbedded sandstone lenses, very hard with weathered layers
Bottom of test boring at fourteen and one-half (14.5) feet
US
CS
CL
CL
GR
AP
HIC
Sam
ples
Blo
w C
ount
Wat
er L
evel
REMARKS
6/6
12/6
50/6
50/6
PN: 53088GE May 6, 2013
APPENDIX B
Laboratory Test Results
Sample SourceSoil DescriptionSwell Pressure (P.S.F)
Initial FinalMoisture Content (%) 8.0 18.3Dry Density (P.C.F) 108.0 112.9Height (in.) 1.000 0.957Diameter (in.) 1.94 1.94
Project NumberDateFigure
SWELL - CONSOLIDATION TEST
SUMMARY OF TEST RESULTS PH II, TB-4@2'
4.1
Sandy Clay (CL)1,030
53088GEJune 20, 2013
-5-4.5
-4-3.5
-3-2.5
-2-1.5
-1-0.5
00.5
10 100 1000 10000Pressure (Pounds per Square Foot)
Con
solid
atio
n %
Sw
ell
Swell/Consolidation due to wetting under constant load
Water added to sample
Sample SourceSoil DescriptionSwell Pressure (P.S.F)
Initial FinalMoisture Content (%) 6.2 19.4Dry Density (P.C.F) 102.3 112.7Height (in.) 1.000 0.897Diameter (in.) 1.94 1.94
Project NumberDateFigure
SWELL - CONSOLIDATION TEST
SUMMARY OF TEST RESULTS PH. II, TB-5@2'
4.2
Sandy Clay (CL)510
53088GEJune 20, 2013
-12
-10
-8
-6
-4
-2
010 100 1000 10000
Pressure (Pounds per Square Foot)
Con
solid
atio
n %
Sw
ell
Swell/Consolidation due to wetting under constant load
Water added to sample
Sample SourceSoil DescriptionSwell Pressure (P.S.F)
Initial FinalMoisture Content (%) 4.2 11.7Dry Density (P.C.F) 133.8 134.6Height (in.) 1.000 0.985Diameter (in.) 1.94 1.94
Project NumberDateFigure
SWELL - CONSOLIDATION TEST
SUMMARY OF TEST RESULTS PH. II, TB-6@7'
4.3
Sandstone1,410
53088GEJune 20, 2013
-2
-1.5
-1
-0.5
0
0.5
110 100 1000 10000
Pressure (Pounds per Square Foot)
Con
solid
atio
n %
Sw
ell
Swell/Consolidation due to wetting under constant load
Water added to sample
Sample SourceSoil DescriptionSwell Pressure (P.S.F)
Initial FinalMoisture Content (%) 4.9 13.5Dry Density (P.C.F) 121.8 124.6Height (in.) 1.000 0.968Diameter (in.) 1.94 1.94
Project NumberDateFigure
SWELL - CONSOLIDATION TEST
SUMMARY OF TEST RESULTS PH. II, TB-7@4'
4.4
Sandstone1,120
53088GEJune 20, 2013
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
0.510 100 1000 10000
Pressure (Pounds per Square Foot)
Con
solid
atio
n %
Sw
ell
Swell/Consolidation due to wetting under constant load
Water added to sample
Sample SourceSoil DescriptionSwell Pressure (P.S.F)
Initial FinalMoisture Content (%) 7.5 15.1Dry Density (P.C.F) 123.2 121.8Height (in.) 1.000 1.021Diameter (in.) 1.94 1.94
Project NumberDateFigure
SWELL - CONSOLIDATION TEST
SUMMARY OF TEST RESULTS PH. II, TB-8@9'
4.5
Sandstone7,620
53088GEJune 20, 2013
-2
0
2
4
6
8
1010 100 1000 10000
Pressure (Pounds per Square Foot)
Con
solid
atio
n %
Sw
ell
Swell/Consolidation due to wetting under constant loadWater added to sample
Sample SourceSoil DescriptionSwell Pressure (P.S.F)
Initial FinalMoisture Content (%) 7.8 15.1Dry Density (P.C.F) 123.8 122.4Height (in.) 1.000 1.005Diameter (in.) 1.94 1.94
Project NumberDateFigure
SWELL - CONSOLIDATION TEST
SUMMARY OF TEST RESULTS PH. II, TC-3@9'
4.6
Sandy Claystone2,940
53088GEJune 21, 2013
-4
-2
0
2
4
6
8
1010 100 1000 10000
Pressure (Pounds per Square Foot)
Con
solid
atio
n %
Sw
ell
Swell/Consolidation due to wetting under constant load
Water added to sample
PN: 53088GE
November 7, 2013
Appendix C
1
APPENDIX C
November 7, 2013 Design Level Report
This Appendix provides excerpts and a tabulation of the shallow test borings (TB1-TB20)
that were advanced as part of the Data Report (Phase I Study) for this project and the test
boring Logs from the Data Report.
PN: 53088GE
November 7, 2013
Appendix C
2
3.3 Subsurface Soil and Water Conditions-Excerpt from May 6, 2013 Data Report
We advanced twenty (20) shallow depth auger test borings in a grid pattern across the
site with an additional eight (8) deeper depth continuous flight auger test borings and four
(4) NQ-Wireline rock core borings advanced with an emphasis on obtaining information
within the northwest and southeast quadrants of the site. The approximate locations of
the test borings are shown on Figure 1. The subsurface conditions encountered in our
shallow test borings are tabulated below with the logs of the remaining test borings
shown presented in Appendix A.
We have provided a tabulation of the soil conditions encountered in our shallow depth
test borings that were advanced for the primary purposed of gathering bulk soil samples.
It should be noted that the soil classification information obtained from these test borings
is based solely on our observations of the auger cuttings, therefore the depths of the soils
and the classifications of the materials encountered should be considered as approximate.
The description of the soil materials are shown below the tabulation of the subsurface
conditions. Test boring designation numbers correspond to Figure 1, presented in Section
3.2 above.
Test Boring
Designation
Depth range of
loess soil (Feet)
Depth range of
slightly sandy
clay soil (Feet)
Depth range to
formation (feet)
Bottom of Test
Boring (feet)
1 0-1½ -- 1½ 2 refusal
2 0-2 2-3½ 3½ weathered 4½ refusal
3 0-2½ 2½-4 4-5 weathered 5
4 -- -- 0-4½ 4½
5 0-3 3-4 4-6½ 6½ refusal
6 0-2½ 2½-4 4-5 5
7 0-2½ 2½-4 4-4½ 4½ refusal
8 0-2 2-4½ -- 4½
9 0-3½ 3½-5 5-6½ weathered 6½ refusal
10 0-2½ 2½--3½ 3½ 3½ refusal
11 0-2 -- 2-2½ weathered 2½ refusal
12 0-3 3-6 ½ -- 6½
13 0-4 4-9 -- 9
14 0-3 -- 3-3½ weathered 3½ refusal
15 0-1 1-2½ 2½-5 weathered 5
16 0-2½ 2½-5 5-6 weathered 6
17 0-2 -- 2-3 weathered 3½ refusal
18 0-2½ 2½-3½ 4½-5 weathered 5
19 0-2 2-3 3-5 weathered 5
20 0-1 -- 1-4½ 4½
Please refer to Pages 7 and 8 of the 11-07-2013 report for the locations of these borings
PN: 53088GE
November 7, 2013
Appendix C
3
The Loess soil was encountered in all of the test borings at the depths shown, the
classification of this soil is Clay and sand, slightly silty, scattered sandstone clasts, soft to
medium stiff, slightly moist, red-brown (CL-SC)
The slightly sandy clay soil may be either a thin soil material or highly weathered
formational material, but it was not discernible in these borings. The soil classification is
as follows: Clay, sandy, sandstone clasts, stiff, slightly moist, gray-brown, (CL)
We logged weathered formational material as noted in the tabulation above. Generally
this material was similar to, but slightly harder than the overlying soil mantle.
We noted where auger refusal was encountered in the borings above. The auger used
for the bulk sampling effort was a 6 inch diameter continuous flight auger. Though we
encountered refusal in some of the borings with this auger, we generally were able to
advance a four (4) inch diameter borings into the harder sandstone formation at the site.
Generally we feel that an estimated blow count for the materials in these test borings
where refusal occurred is about 50/2 to 50/4 based on the information obtained from the
deeper test borings where driven samples were taken after these borings had been
completed.
Please refer to the logs of the deeper continuous flight auger borings where driven
samples were taken and the logs of the core borings presented in Appendix A for
additional information.
We encountered about one and one-half (1½) to two and one-half (2½) feet of a loess
soil deposit in our test borings. The upper few inches of this material has more organic
content than deeper layers. The material is essentially very fine sand and silt materials
with a minor amount of clay. Though this material may be considered as generally
suitable for site fill and establishing grade, it is less desirable for use as-is for fill material
for support of flatwork and structural components. We encountered clayey sand in our
borings to variable depths. This material ranged from clayey and silty sand, to clay with
lesser amounts of sand. Generally this soil layer may be considered as existing from
about two (2) to four (4) feet below the surface over about ¾ of the project site for
general planning considerations and volume estimates.
However it should be noted that we did encounter formational material at depths as
shallow as about one and one-half (1½) feet below the ground surface in several testing
borings. If it is desirable to utilize the loess materials for processing and compaction we
suggest that only the lower 12 inches of this material be considered, since the upper
nominally 12 inches of this material contained significant organic material. The lower 12
inches of the loess materials are only suitable or use as fill if they are mixed and blended
with the underlying sandy clay and clay-sand soil. Formational material may be
observed at the ground surface in some areas of the site. The loess soils are more red-
brown in color than are the tan to gray-brown soil below. Generally both of these
shallow soils may be considered as having a low swell potential when wetted and may
PN: 53088GE
November 7, 2013
Appendix C
4
consolidate under light loads. The upper 6 to 12 inches of the loess soil material have
organic materials and should therefore be stockpiled for use as surface planting and
preparation for landscaping and establishment of surface vegetation after the
construction, if the landscape architect or landscape professional determines that they are
suitable for that use.
We encountered lean clay with sandstone fragments in some of our test borings. This
material is somewhat anomalous in that it consist of a lean clay with angular clasts of
sandstone and actually exists within the formational materials as observed in some of our
core borings. It is very atypical for a soil deposit to exist within a formational materials
deposit, however it is possible if there is a sudden climatic change during the depositional
period of the formation. In this case we suspect that the well indurated soil is a result of
short term localized erosion and subsequent deposition of detritus from areas close to the
site. As more normal climatic and depositional characteristics were re-established
additional deposition of the sandstone materials occurred. The Molas formation is one
such map able geologic unit in the Four Corners region that was formed in such a
fashion. The Molas formation may be observed in outcroppings and roadway cuts near
the Durango Mountain Report and other locations in the San Juan Mountains,
The swell tests performed on samples of the clay and sandstone clast material indicates
that it has a very high to extreme swell pressure and potential when wetted and may
consolidate under high loads. The significance of this soil deposit is discussed
additionally under the foundation discussion of this report below.
The site is underlain by the Cretaceous Dakota Sandstone. It should be noted that the
name of this geologic unit is somewhat misleading in that the unit contains more than just
sandstone. Carbonaceaous shale, lignite and coal are all found within the Dakota
Sandstone unit in the Four Corners region. The generally hard, cliff-forming quartzitic
sandstone exposures of this unit are noted throughout Colorado, thus the name of the unit
reflects these omnipresent sandstone beds.
We have had experience in the Cortez area, including recent exploration within a quarter
mile of this site where the sandstone beds of the Dakota are extremely hard and are
suitable for processing and use as rock products. Mesa Sandstone, a local quarry utilizes
sandstone materials
from the Dakota for production of commercial rock products. Although we did find
relatively hard sandstone layers in our core borings, the relatively thin layers of these
hard layers may reduce the viability for utilization of this material on site for rock
products produced on-site.
We did not encounter free subsurface water in our test borings at the time of our field
work. Although we do not feel that it is likely that subsurface water will be encountered
during the project construction, it has been our experience on sites with shallow
formational materials that due to a lack of significant a soil mantle that subsurface water
PN: 53088GE
November 7, 2013
Appendix C
5
migration and temporary perched areas of subsurface water may occur as a result of
heavy precipitation.
The tabulation of the subsurface conditions encountered in our shallow test borings
above and the logs of the test borings presented in Appendix A represent 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.
05-0
6-20
13 T
:\Cur
rent
GE
\530
88G
E, M
CH
S M
onte
zum
a C
orte
z H
igh
Scho
ol\L
ogs
of T
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orin
gs\M
CH
S T
B-21
.bor
Field Engineer : D. TrautnerHole Diameter : 4" solidDrilling Method : Continuous Flight AugerSampling Method : Mod. California SamplerDate Drilled : 04/24/2013Total Depth (approx.) : 14 feetLocation : SW Quadrant
: See Figure in Report
LOG OF BORING TB-21
PN:53083GEMr. Jim Ketter, PE, KPMC
Mr. Alex Carter, SuperintendentMontezuma-Cortez High School
Depthin
feet
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
DESCRIPTION
Sample TypeMod. California Sampler
Bag Sample
Standard Split Spoon
Water LevelWater Level During Drilling
Water Level After Drilling
US
CS
GR
AP
HIC
Sam
ples
Blo
w C
ount
8/6
10/6
30/6
42/6
Wat
er L
evel
REMARKS
6 inches organicsCLAY, sandy, medium stiff, slightly moist, brown to red
Clay and sandstone clasts, very stiff, slightly moist, variegated color
FORMATIONAL MATERIAL, Dakota Sandstone Formation, very hard, dry, tan
Auger refusal at fourteen (14) feet
CL
CL-GC
05-0
6-20
13 T
:\Cur
rent
GE
\530
88G
E, M
CH
S M
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ogs
of T
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orin
gs\M
CH
S T
B-22
.bor
Field Engineer : D. TrautnerHole Diameter : 4" solidDrilling Method : Continuous Flight AugerSampling Method : Mod. California SamplerDate Drilled : 04/24/2013Total Depth (approx.) : 6 feetLocation : See Figure in Report
LOG OF BORING TB-22
PN:53083GEMr. Jim Ketter, PE, KPMC
Mr. Alex Carter, SuperintendentMontezuma-Cortez High School
Depthin
feet
0
1
2
3
4
5
6
7
DESCRIPTION
Sample TypeMod. California Sampler
Bag Sample
Standard Split Spoon
Water LevelWater Level During Drilling
Water Level After Drilling
US
CS
GR
AP
HIC
Sam
ples
Blo
w C
ount
10/6
19/6
Wat
er L
evel
REMARKS
Loess
CLAY, sandy, medium stiff, slightly moist, brown to red
CLAY, GRAVEL, sandstone clasts, stiff, slightly moist, brown to gray
FORMATIONAL MATERIAL, Dakota Sandstone Formation, very hard, dry, tan
Auger refusal at six (6) feet
CL
CL-GC
05-0
6-20
13 T
:\Cur
rent
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\530
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E, M
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orin
gs\M
CH
S T
B-23
.bor
Field Engineer : D. TrautnerHole Diameter : 4" solidDrilling Method : Continuous Flight AugerSampling Method : Mod. California SamplerDate Drilled : 04/24/2013Total Depth (approx.) : 5 feetLocation : See Figure in Report
LOG OF BORING TB-23
PN:53083GEMr. Jim Ketter, PE, KPMC
Mr. Alex Carter, SuperintendentMontezuma-Cortez High School
Depthin
feet
0
1
2
3
4
5
6
DESCRIPTION
Sample TypeMod. California Sampler
Bag Sample
Standard Split Spoon
Water LevelWater Level During Drilling
Water Level After Drilling
US
CS
GR
AP
HIC
Sam
ples
Blo
w C
ount
50/4
Wat
er L
evel
REMARKS
Loess
CLAY, sandy, medium stiff, moist, brown to red
WEATHERED FORMATIONAL MATERIAL, sandstone, medium dense, slightly moist, tan
FORMATIONAL MATERIAL, Dakota Sandstone Formation, very hard, dry, tan
Auger refusal at five (5) feet
CL
05-0
6-20
13 T
:\Cur
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\530
88G
E, M
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of T
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orin
gs\M
CH
S T
B-24
.bor
Field Engineer : D. TrautnerHole Diameter : 4" solidDrilling Method : Continuous Flight AugerSampling Method : Mod. California SamplerDate Drilled : 04/24/2013Total Depth (approx.) : 18 feetLocation : See Figure in Report
LOG OF BORING TB-24
PN:53083GEMr. Jim Ketter, PE, KPMC
Mr. Alex Carter, SuperintendentMontezuma-Cortez High School
Depthin
feet
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
DESCRIPTION
Sample TypeMod. California Sampler
Bag Sample
Standard Split Spoon
Water LevelWater Level During Drilling
Water Level After Drilling
US
CS
GR
AP
HIC
Sam
ples
Blo
w C
ount
50/6
Wat
er L
evel
REMARKS
LoessCLAY, silty, sandy, few sandstone cobbles, medium soft, slightly moist, brown to red
WEATHERED FORMATIONAL MATERIAL, interbedded sandstone and claystone, medium dense, slightly moist, tan
FORMATIONAL MATERIAL, interbedded claystone and sandstone, hard, dry, tan
Sandstone lenses 3 to 6 inches in thickness
Auger refusal at eighteen (18) feet
CL-ML
05-0
6-20
13 T
:\Cur
rent
GE
\530
88G
E, M
CH
S M
onte
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orte
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ol\L
ogs
of T
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orin
gs\M
CH
S T
B-25
.bor
Field Engineer : D. TrautnerHole Diameter : 4" solidDrilling Method : Continuous Flight AugerSampling Method : Mod. California SamplerDate Drilled : 04/24/2013Total Depth (approx.) : 9 feetLocation : See Figure in Report
LOG OF BORING TB-25
PN:53083GEMr. Jim Ketter, PE, KPMC
Mr. Alex Carter, SuperintendentMontezuma-Cortez High School
Depthin
feet
0
1
2
3
4
5
6
7
8
9
10
DESCRIPTION
Sample TypeMod. California Sampler
Bag Sample
Standard Split Spoon
Water LevelWater Level During Drilling
Water Level After Drilling
US
CS
GR
AP
HIC
Sam
ples
Blo
w C
ount
21/6
29/6
Wat
er L
evel
REMARKS
Loess
CLAY, silty, sandy, medium stiff to soft, slightly moist, brown to red
CLAY, GRAVEL, scattered sandstone fragments, medium stiff to stiff, slightly moist, brown to gray
Bottom of test boring at nine (9) feet
CL
CL-SC
05-0
6-20
13 T
:\Cur
rent
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\530
88G
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orin
gs\M
CH
S T
B-26
.bor
Field Engineer : D. TrautnerHole Diameter : 4" solidDrilling Method : Continuous Flight AugerSampling Method : Mod. California SamplerDate Drilled : 04/24/2013Total Depth (approx.) : 10 feetLocation : See Figure in Report
LOG OF BORING TB-26
PN:53083GEMr. Jim Ketter, PE, KPMC
Mr. Alex Carter, SuperintendentMontezuma-Cortez High School
Depthin
feet
0
1
2
3
4
5
6
7
8
9
10
11
DESCRIPTION
Sample TypeMod. California Sampler
Bag Sample
Standard Split Spoon
Water LevelWater Level During Drilling
Water Level After Drilling
US
CS
GR
AP
HIC
Sam
ples
Blo
w C
ount
16/6
36/6
50/6
Wat
er L
evel
REMARKS
Disturbed ground surface
Lost sampler
CLAY, silty, sandy, medium stiff to soft, slightly moist, brown
FORMATIONAL MATERIAL, sandy claystone, firm to medium hard, dry, gray to brown
Bottom of test boring at ten (10) feet
CL
05-0
6-20
13 T
:\Cur
rent
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\530
88G
E, M
CH
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onte
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Scho
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orin
gs\M
CH
S T
B-27
.bor
Field Engineer : D. TrautnerHole Diameter : 4" solidDrilling Method : Continuous Flight AugerSampling Method : Mod. California SamplerDate Drilled : 04/24/2013Total Depth (approx.) : 15 feetLocation : North Central
: See Figure in Report
LOG OF BORING TB-27
PN:53083GEMr. Jim Ketter, PE, KPMC
Mr. Alex Carter, SuperintendentMontezuma-Cortez High School
Depthin
feet
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
DESCRIPTION
Sample TypeMod. California Sampler
Bag Sample
Standard Split Spoon
Water LevelWater Level During Drilling
Water Level After Drilling
US
CS
GR
AP
HIC
Sam
ples
Blo
w C
ount
50/3
Wat
er L
evel
REMARKS
CLAY, silty, sandy, medium stiff to soft, slightly moist, brown
WEATHERED FORMATIONAL MATERIAL, interbedded claystone and sandstone, friable, medium dense, dry, tan to brown
Sandstone layers to 12 inches thick
Bottom of test boring at fifteen (15) feet
CL
05-0
6-20
13 T
:\Cur
rent
GE
\530
88G
E, M
CH
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onte
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orte
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igh
Scho
ol\L
ogs
of T
est B
orin
gs\M
CH
S T
B-28
.bor
Field Engineer : D. TrautnerHole Diameter : 4" solidDrilling Method : Continuous Flight AugerSampling Method : Mod. California SamplerDate Drilled : 04/24/2013Total Depth (approx.) : 5 feetLocation : See Figure in Report
LOG OF BORING TB-28
PN:53083GEMr. Jim Ketter, PE, KPMC
Mr. Alex Carter, SuperintendentMontezuma-Cortez High School
Depthin
feet
0
1
2
3
4
5
6
DESCRIPTION
Sample TypeMod. California Sampler
Bag Sample
Standard Split Spoon
Water LevelWater Level During Drilling
Water Level After Drilling
US
CS
GR
AP
HIC
Sam
ples
Blo
w C
ount
22/6
21/6
Wat
er L
evel
REMARKS
CLAY, silty, sandy, few cobbles, clasts of sandstone, medium stiff, slightly moist, brown
WEATHERED FORMATIONAL MATERIAL, claystone and sandstone, firm, dry, tan
Bottom of test boring at five (5) feet
CL
05-0
2-20
13 T
:\Cur
rent
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\530
88G
E, M
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onte
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gs\M
CH
S T
C-1
.bor
Field Engineer : J. ButlerHole Diameter : NQDrilling Method : Wireline CoreSampling Method : NQ CoreDate Drilled : April 29,2013Total Depth : 21.5 feetLocation : See Figure in Report
LOG OF BORING TC-1
PN: 53083GEMr. Jim Ketter, PE, KPMC
Mr. Alex Carter, SuperintendentMontezuma-Cortez High School
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
DESCRIPTION
NQ Core
Clay, sandy, medium stiff, slightly moist to moist, red (CL)
WEATHERED FORMATIONAL MATERIAL, Dakota Sandstone Formation, weathered claystone with thin interbedded sandstone, tan, little return in core
SANDY CLAYSTONE, interbedded sandstone lenses with clay infilling, highly fractured, brown/gray
SANDY CLAYSTONE, highly fractured, brown/gray
CLAYEY SANDSTONE, highly fractured, tan/brown
SANDSTONE, improved competency, white
Bottom of Core Run at twenty one and one-half (21-1/2) feet
US
CS
CL
GR
AP
HIC
Run
dep
th
Recovery and R.Q.D.
Top of First Run at five (5) feetRecovery= 11% R.Q.D= 0%
Bottom of First Run at six and one-half (6.5) feetTop of Second Run at six and one-half (6.5) feet
Recovery= 68%R.Q.D.= 0%
Bottom of Second Run at eleven and one-half (11.5) feet Top of Third Run at eleven and one-half (11.5) feet
Recovery= 100%R.Q.D.= 0%
Bottom of Third Run at sixteen and one-half (16.5) feetTop of Fourth Run at sixteen and one-half (16.5) feet
Recovery=100%R.Q.D.= 11%
Bottom of Fourth Run at twenty one and one-half (21.5) feet
05-0
2-20
13 T
:\Cur
rent
GE
\530
88G
E, M
CH
S M
onte
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Scho
ol\L
ogs
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gs\M
CH
S T
C-2
.bor
Field Engineer : J. ButlerHole Diameter : NQDrilling Method : Wireline CoreSampling Method : NQ CoreDate Drilled : April 29,2013Total Depth : 27 feetLocation : See Figure in Report
LOG OF BORING TC-2
PN: 53083GEMr. Jim Ketter, PE, KPMC
Mr. Alex Carter, SuperintendentMontezuma-Cortez High School
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
DESCRIPTION
NQ Core
Clay, sandy, medium stiff, slightly moist to moist, red (CL)
WEATHERED FORMATIONAL MATERIAL, Dakota Sandstone Formation, sandstone, hard, dry, tan/whiteSANDSTONE, minor fractures, very hard, tan/brown
SANDSTONE, minor fractures, tan/white
SANDSTONE, highly fractured, tan
CLAYEY SANDSTONE, highly fractured, tan/brown
SANDY CLAYSTONE, highly fractured, tan/brown
Bottom of Core Run at twenty-seven (27) feet
US
CS
CL
GR
AP
HIC
Run
dep
th
Recovery and R.Q.D.
Top of First Run at two (2) feet
Recovery= 100% R.Q.D= 89%
Bottom of First Run at seven (7) feetTop of Second Run at seven (7) feet
Recovery= 100%R.Q.D.= 92%
Bottom of Second Run at twelve (12) feet Top of Third Run at twelve (12) feet
Recovery= 100%R.Q.D.= 0%
Bottom of Third Run at seventeen (17) feetTop of Fourth Run at seventeen (17) feet
Recovery=100%R.Q.D.= 11%
Bottom of Fourth Run at twenty-two (22) feetTop of Fifth Run at twenty-two (22) feet
Recovery=100%R.Q.D.= 0%
Bottom of Fifth Run at twenty-seven (27) feet
05-0
2-20
13 T
:\Cur
rent
GE
\530
88G
E, M
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S M
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Scho
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ogs
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est B
orin
gs\M
CH
S T
C-3
.bor
Field Engineer : J. ButlerHole Diameter : NQDrilling Method : Wireline CoreSampling Method : NQ CoreDate Drilled : April 30,2013Total Depth : 36.5 feetLocation : See Figure in Report
LOG OF BORING TC-3
PN: 53083GEMr. Jim Ketter, PE, KPMC
Mr. Alex Carter, SuperintendentMontezuma-Cortez High School
Depthin
feet
0123456789
10111213141516171819202122232425262728293031323334353637383940
DESCRIPTION
NQ Core
Clay, sandy, medium stiff, dry, red (CL)
WEATHERED FORMATIONAL MATERIAL, Dakota Sandstone Formation, interbedded claystone and sandstone, hard, moist, tan
SANDSTONE, interbedded claystone, highly fractured, tan
SANDY CLAYSTONE, interbedded shale, hgihly fractured, tan/brown
SANDSTONE, moderately fractured, tan/white
SANDY CLAYSTONE, interbedded shale, highly fractured, tan/brown
SANDSTONE, gypsum veins, moderately fractured, tan/white
LIGNITE LAYER
SANDSTONE, moderately fractured, tan
Bottom of Core Run at thirty six and one-half (36.5) feet
US
CS
CL
GR
AP
HIC
Run
dep
th
Recovery and R.Q.D.
Top of First Run at three (3) feet
Recovery= 100% R.Q.D= 0% Bottom of First Run at six and one-half (6.5) feetTop of Second Run at six and one-half (6.5) feet
Recovery= 100%R.Q.D.= 0%
Bottom of Second Run at eleven and one-half (11.5) feet Top of Third Run at eleven and one-half (11.5) feet
Recovery= 82%R.Q.D.= 13%
Bottom of Third Run at sixteen and one-half (16.5) feetTop of Fourth Run at sixteen and one-half (16.5) feet
Recovery=100%R.Q.D.= 0%
Bottom of Fourth Run at twenty one & one-half (21.5) feetTop of Fifth Run at twenty one and one-half (21.5) feet
Recovery=100%R.Q.D.= 58%
Bottom of Fifth Run at twenty six and one-half (26.5) feetTop of Sixth Run at twenty six and one-half (26.5) feet
Recovery= 90%R.Q.D.= 17%
Bottom of Seventh Run thirty one and one-half (31.5) feetTop of Eighth Run at thirty one and one-half (31.5) feet
Recovery=100%R.Q.D.= 58%
Bottom of Eighth Run at thrity six and one-half (36.5) feet
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C-4
.bor
Field Engineer : J. ButlerHole Diameter : NQDrilling Method : Wireline CoreSampling Method : NQ CoreDate Drilled : April 30,2013Total Depth : 22.5 feetLocation : See Figure in Report
LOG OF BORING TC-4
PN: 53083GEMr. Jim Ketter, PE, KPMC
Mr. Alex Carter, SuperintendentMontezuma-Cortez High School
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
DESCRIPTION
NQ Core
Clay, sandy, medium stiff, slightly moist to moist, red (CL)
WEATHERED FORMATIONAL MATERIAL, Dakota Sandstone Formation, highly fractured
CLAYEY SANDSTONE, highly fractured, tan
SANDY CLAYSTONE, highly fractured, tan/brown
SANDSTONE, highly fractured, tan/white
Bottom of Core Run at twenty two and one-half (22.5) feet
US
CS
CL
GR
AP
HIC
Run
dep
th
Recovery and R.Q.D.
Top of First Run at four (4) feet
Recovery= 100% R.Q.D= 0%
Bottom of First Run at seven and one-half (7.5) feetTop of Second Run at seven and one-half (7.5) feet
Recovery= 100%R.Q.D.= 0%
Bottom of Second Run at twelve and one-half (12.5) feet Top of Third Run at twelve and one-half (12.5) feet
Recovery= 100%R.Q.D.= 27%
Bottom of Third Run at seventeen and one-half (17.5) feetTop of Fourth Run at seventeen and one-half (17.5) feet
Recovery=100%R.Q.D.= 0%
Bottom of Fourth Run at twenty two and one-half (22.5) feet