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Geotechnical Engineering and Materials Testing
PRELIMINARY GEOTECHNICAL
ENGINEERING REPORT
Proposed Commercial or Mixed-Use Development
SWC of South College Avenue and West Drake Road
Fort Collins, Colorado
Prepared For:
Kentro Group
1509 York Street, Suite 201
Denver, Colorado 80206
Prepared By:
Cole Garner Geotechnical
CGG Project No.: 25.22.081
July 1, 2025
Geotechnical Engineering and Materials Testing
Cole Garner Geotechnical
1070 W. 124th Ave, Ste. 300
Westminster, CO 80234
303.996.2999
July 1, 2025
Kentro Group
1509 York Street, Suite 201
Denver, Colorado 80206
Attn: Logan Heath
Re: Preliminary Geotechnical Engineering Report
Proposed Commercial or Mixed-Use Development
SWC of South College Avenue and West Drake Road
Fort Collins, Colorado
CGG Project No. 25.22.081
Cole Garner Geotechnical (CGG) has completed a geotechnical engineering investigation for the
proposed commercial or mixed-use development to be constructed at the referenced site in Fort Collins,
Colorado. This geotechnical summary should be used in conjunction with the entire report for design
and/or construction purposes. It should be recognized that specific details were not included or fully
developed in this section, and the report must be read in its entirety for a comprehensive understanding of
the items contained herein. The section titled General Comments should be read for an understanding of
the report limitations.
• Subsurface Conditions: Subsurface conditions at the site consisted of lean clays with varying
amounts of sand and clayey to silty sands. Existing man-made fill soils comprised of sandy lean clay
to clayey sand were encountered in Boring No. P1 to a depth of about 5 feet below existing site
grade. Existing fill soils should also be anticipated across at least portions of the site associated
with the existing development. Sedimentary sandstone bedrock was encountered underlying the
clays/sands in three of the borings at depths ranging from about 30 to 36 feet below the ground
surface. The bedrock extended to the depth of exploration, where present. Other specific
information regarding the subsurface conditions is shown on the attached Boring Logs.
• Groundwater Conditions: Groundwater was measured in our borings at depths ranging from about
13 to 18 feet below existing site grades, similar to those reported in a prior geotechnical study
(Soilogic; July 2018) for the site at depths ranging from about 11-½ to 15 feet below the ground
surface. These measurements are only representative of groundwater conditions at the time
measured and may not be indicative of “high” groundwater elevation. Based on these
measurements, we do not believe that groundwater will limit normal construction of basement,
crawlspace, elevator pits or vaults on the site, if desired. However, we recommend that any
basement or other below-grade foundations bear a minimum of three feet above “seasonal high
groundwater elevation”. In addition, foundation drain systems will be required at the base of these
Preliminary Geotechnical Engineering Report
Proposed Commercial or Mixed-Use Development – S. College Avenue & W. Drake Road, Fort Collins, CO
CGG Project No. 25.22.081
Cole Garner Geotechnical Page ii
Geotechnical Engineering and Materials Testing
areas and behind any walls which retain more than 2 to 3 feet of earth (unless they are designed for
hydrostatic pressures).
• Existing Fills, Demolition, and Site Preparation: The existing development (existing buildings,
pavements, utilities, and flatwork, etc.) will be demolished and removed from the site as part of the
new development. Demolition and removal of these features will likely expose or generate soft or
loose soil conditions. Demolition should include removal of shallow foundations, underground
utilities, and mitigation of any loose or otherwise unsuitable backfill materials. Any unsuitable
existing fill soils should be removed and recompacted, where present below planned
improvements.
• Structural Considerations: Field and laboratory data from samples obtained from our borings
suggest that the existing soils are low expansive at existing moisture contents; these soils should be
suitable for support of spread footing foundations and slab-on-grade floors provided that typical
movement can be tolerated. However, some soft soil conditions may be encountered and may
require mitigation to support new structural loads. Mitigation to provide for a stable base below
foundations and floor slabs typically includes limited subexcavation, moisture-conditioning, and
recompaction of any unsuitable materials to provide a relatively uniform thickness of approved
engineered fill below these elements. If heavily-loaded structures are planned for the site, the use
of deep foundations may be appropriate to support these loads and help limit foundation
movement.
• Future Additional Geotechnical Studies: The scope of services for this current study included a
general evaluation of subsurface conditions to identify main geotechnical issues or concerns that
may affect development of the project. Supplemental design-level geotechnical explorations, with
additional structure-specific borings will be required to develop design-level recommendations for
structures and to confirm and/or modify the preliminary recommendations and conclusions
contained in this report. In addition, formal pavement design studies for final design of any public
roadway improvements will be required.
We appreciate being of service to you in the geotechnical engineering phase of this project and are
prepared to assist you during the construction phases as well. Please do not hesitate to contact us if you
have any questions concerning this report or any of our testing, inspection, design and consulting
services.
Sincerely,
Cole Garner Geotechnical
Glenn D. Ohlsen, P.E. Andrew J. Garner, P.E.
Sr. Project Engineer Principal, COO
7/1/2025
Preliminary Geotechnical Engineering Report
Proposed Commercial or Mixed-Use Development – S. College Avenue & W. Drake Road, Fort Collins, CO
CGG Project No. 25.22.081
Cole Garner Geotechnical Page iii
Geotechnical Engineering and Materials Testing
TABLE OF CONTENTS
Page No.
Letter of Transmittal .............................................................................................................................. ii
INTRODUCTION ..................................................................................................................................... 1
PROJECT INFORMATION ....................................................................................................................... 2
SITE EXPLORATION PROCEDURES ......................................................................................................... 2
Field Exploration ............................................................................................................................. 2
Laboratory Testing .......................................................................................................................... 3
SITE CONDITIONS .................................................................................................................................. 3
SUBSURFACE CONDITIONS ................................................................................................................... 4
Geology ........................................................................................................................................... 4
Soil and Bedrock Conditions ............................................................................................................ 4
Field and Laboratory Test Results ................................................................................................... 4
Groundwater Conditions ................................................................................................................. 5
ENGINEERING RECOMMENDATIONS .................................................................................................... 5
Geotechnical Considerations .......................................................................................................... 5
Earthwork ........................................................................................................................................ 6
General Considerations ............................................................................................................ 6
Demolition and Site Preparation .............................................................................................. 6
Subgrade Preparation ............................................................................................................... 7
Fill Materials ............................................................................................................................. 7
Fill Placement and Compaction ................................................................................................ 8
Excavation and Trench Construction ........................................................................................ 8
Conceptual Structural Considerations ............................................................................................ 9
Design of Private Pavements ........................................................................................................ 10
Final Grading, Landscaping, and Surface Drainage ....................................................................... 15
Additional Design and Construction Considerations ..................................................................... 16
Exterior Slab Design and Construction ................................................................................... 16
Underground Utility Systems .................................................................................................. 16
Concrete Corrosion Protection ............................................................................................... 16
Future Additional Geotechnical Studies ................................................................................. 17
GENERAL COMMENTS ......................................................................................................................... 17
APPENDIX A: BORING LOCATION DIAGRAM, BORING LOGS
APPENDIX B: LABORATORY TEST RESULTS
APPENDIX C: GENERAL NOTES
Geotechnical Engineering and Materials Testing
Cole Garner Geotechnical
1070 W. 124th Ave, Ste. 300
Westminster, CO 80234
303.996.2999
PRELIMINARY GEOTECHNICAL ENGINEERING REPORT
PROPOSED COMMERCIAL or MIXED-USE DEVELOPMENT
SWC of SOUTH COLLEGE AVENUE and WEST DRAKE ROAD
FORT COLLINS, COLORADO
CGG Project No. 25.22.081
July 1, 2025
INTRODUCTION
This report contains the results of our geotechnical engineering exploration for the proposed
commercial or mixed-use development to be constructed at the southwest corner of the referenced
intersection in Fort Collins, Colorado. This study was performed in general accordance with our proposal
(CGG Proposal No. P25.22.029) executed May 12, 2025.
The purpose of these services is to provide information and geotechnical engineering recommendations
relative to:
• Geologic conditions
• Subsurface soil and bedrock conditions
• Groundwater conditions
• Site preparation and earthwork
• Preliminary structure foundation alternatives
• Below-grade construction
• Preliminary/design pavement sections
• Surface and subsurface drainage
The recommendations contained in this report are based upon the results of field and laboratory
testing, engineering analyses, our experience with similar subsurface conditions and structures, and our
understanding of the proposed project.
As part of preparation of this report, we have reviewed the following report previously prepared for the
site:
• Geotechnical Subsurface Exploration Report – Spradley Barr Redevelopment, Fort Collins,
Colorado, prepared by Soilogic, (Project No. 18-1206) dated July 27, 2018.
Preliminary Geotechnical Engineering Report
Proposed Commercial or Mixed-Use Development – S. College Avenue & W. Drake Road, Fort Collins, CO
CGG Project No. 25.22.081
Cole Garner Geotechnical Page 2
Geotechnical Engineering and Materials Testing
PROJECT INFORMATION
We understand the proposed project will include redevelopment and subdivision of the approximate
6.9-acre parcel into a commercial or mixed-use development. Based on review of Google aerial and
street view imagery, the site appears to have been most recently utilized for commercial purposes;
existing commercial buildings and paved parking and drive lane areas are currently present at the site.
The site is planned to be divided into four commercial lots, as shown on the attached Boring Location
Diagram. Existing development will be demolished and removed from the site(s). New development
will include limited site grading, underground utility installation, and the construction of paved private
drives and fire lanes to support the future commercial/mixed-use development. We assume that
eventual building construction may include conventional wood, CMU or steel-frame structures,
supported on reinforced concrete foundations. Basement construction may be included.
Although grading plans were not provided, based on existing topography, we assume limited site
grading will be required for the site, with maximum earthen cut/fill on the order of 3 feet to bring the
site to construction grade. If our assumptions above are not accurate, or if you have additional useful
information, please inform us as soon as possible.
SITE EXPLORATION PROCEDURES
The scope of the services performed for this project included site reconnaissance by an engineer, a
subsurface exploration program, laboratory testing and engineering analysis.
Field Exploration: We investigated the subsurface conditions on the site with a total of eight test borings.
Borings were advanced with a truck-mounted drilling rig utilizing 4-inch diameter, solid stem auger.
Structural borings were advanced to depths of about 25 to 40 feet below existing site grades, while
pavement borings were advanced to a depth of about 10 feet below existing site grades. Refer to Figure 1
– Boring Location Diagram in Appendix A for the approximate boring locations on the project site.
A lithologic log of each boring was recorded by our field personnel during the drilling operations. At
selected intervals, samples of the subsurface materials were obtained by driving modified California
barrel samplers. Penetration resistance measurements were obtained by driving the sample barrel into
the subsurface materials with a 140-pound automatic hammer falling 30 inches. The penetration
resistance value is a useful index to the consistency, relative density or hardness of the materials
encountered.
Groundwater measurements were made in each boring at the time of site exploration. Due to safety
considerations, all borings (with the exception of Boring No. 4) were backfilled immediately after drilling
and patched at the surface with asphalt cold-patch material. When checked again in Boring No. 4 about
Preliminary Geotechnical Engineering Report
Proposed Commercial or Mixed-Use Development – S. College Avenue & W. Drake Road, Fort Collins, CO
CGG Project No. 25.22.081
Cole Garner Geotechnical Page 3
Geotechnical Engineering and Materials Testing
three weeks later, the boring had caved above groundwater (as noted on the boring log), so that
measurement was not possible.
Laboratory Testing: Samples retrieved during the field exploration were returned to the laboratory for
observation by the project geotechnical engineer, and were classified in general accordance with the
Unified Soil Classification System and Rock Classification notes summarized in Appendix C. At that time,
an applicable laboratory-testing program was formulated to determine engineering properties of the
subsurface materials. Following the completion of the laboratory testing, the field descriptions were
confirmed or modified as necessary, and Boring Logs were prepared. These logs are presented in
Appendix A.
Laboratory test results are presented in Appendix B. These results were used for the geotechnical
engineering analyses and the development of foundation and earthwork recommendations. Laboratory
tests were performed in general accordance with the applicable local or other accepted standards.
Selected soil and bedrock samples were tested for the following engineering properties:
• Water content
• Dry density
• Swell/Consolidation
• Grain size
• Plasticity Index
• Water-soluble sulfates
SITE CONDITIONS
The site consists of existing commercial lots, totaling approximately 6.94-acres, located at the southwest
corner of South College Avenue and West Drake Road in Fort Collins, Colorado. The site is bound by
South College Avenue to the east, West Drake Road to the north, McClelland Drive to the west, West
Thunderbird Drive to the south, and existing commercial lots to the southeast. The extents of the site
are shown on Figure 1 – Boring Location Diagram in Appendix A. At the time of our field exploration,
vacant buildings from the prior automotive dealership and asphalt paved drive lanes and parking areas
were present across the site. Two existing buildings for current businesses were also in place within the
southeast portion of the site. The site appears relatively flat. Based on review of USGS mapping, the site
has a general downward slope to the east, with an estimated elevation drop of about 10 feet across the
site.
Preliminary Geotechnical Engineering Report
Proposed Commercial or Mixed-Use Development – S. College Avenue & W. Drake Road, Fort Collins, CO
CGG Project No. 25.22.081
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Geotechnical Engineering and Materials Testing
SUBSURFACE CONDITIONS
Geology: Surficial geologic conditions on portions of the site, as mapped by the U.S. Geological Survey
(USGS) (1Workman, et all, 2018) and (2Colton, 1978), consist of Slocum Alluvium of Middle Pleistocene
Age. These materials are typically reported to include clay, sand, gravel, and boulders.
Bedrock underlying the surface units consists of Pierre Shale of Upper Cretaceous Age. This formation
within this area has been reported to include interbedded claystone, siltstone, sandstone, and shale.
Mapping completed by the Colorado Geological Survey (3Hart, 1972) indicates the site is located in an
area of "Moderate Swell Potential”. This category generally includes several bedrock formations and a
few surficial deposits. The soils encountered in our borings exhibited low swell (expansive) potential at
existing moisture contents.
No other geologic hazards were identified at the site. It is assumed that with proper site grading design,
flooding and erosional problems at the site should be reduced.
Soil and Bedrock Conditions: Subsurface conditions at the site consisted of lean clays with varying
amounts of sand and clayey to silty sands. Existing man-made fill soils comprised of sandy lean clay to
clayey sand were encountered in Boring No. P1 to a depth of about 5 feet below existing site grade.
Existing fill soils should also be anticipated across at least portions of the site associated with the
existing development. Sedimentary sandstone bedrock was encountered underlying the clays/sands in
three of the borings at depths ranging from about 30 to 36 feet below the ground surface. The bedrock
extended to the depth of exploration, where present. Other specific information regarding the
subsurface conditions is shown on the attached Boring Logs.
Field and Laboratory Test Results: Field test results indicate that the native clay soils range from soft to
very stiff in consistency; the clay fill soils are soft. The sand soils are loose in relative density. The
bedrock is very hard based on field penetration testing.
Laboratory test results indicate that the lean clay soils exhibited moderate plasticity. These clay soils
exhibited low expansive potential at existing moisture contents. Multiple samples exhibited low
settlement/consolidation when wetted under relatively light loads; when loaded further some of these
samples exhibited moderate to high consolidation. Testing of select soil samples for the presence of
water-soluble sulfates indicated concentrations of nil (0) parts per million (ppm).
1 Workman, J.B., Cole, J.C., Shroba, R.R., Kellogg, K.S., and Premo, W.R., 2018, Geologic Map of the Fort Collins 30’ x 60’ Quadrangle,
Larimer and Jackson Counties, Colorado, and Albany and Laramie Counties, Wyoming, United States Geological Survey, Scientific
Investigations Map SIM-3399.
2 Colton, R.B., 1978, Geologic Map of the Boulder - Fort Collins – Greeley Area, Front Range Urban Corridor, Colorado, United States
Geological Survey, Map I-855-G.
3 Hart, Stephen S., 1972, Potentially Swelling Soil and Rock in the Front Range Urban Corridor, Colorado, Colorado Geological Survey,
Sheet 2 of 4.
Preliminary Geotechnical Engineering Report
Proposed Commercial or Mixed-Use Development – S. College Avenue & W. Drake Road, Fort Collins, CO
CGG Project No. 25.22.081
Cole Garner Geotechnical Page 5
Geotechnical Engineering and Materials Testing
Groundwater Conditions: Groundwater was encountered in the deeper borings during drilling at depths
ranging from about 13 to 18 feet below the ground surface. Due to safety considerations, all borings
(with the exception of Boring No. 4) were backfilled immediately after drilling. When checked again
about three weeks later, Boring No. 4 had caved above groundwater, so that measurement was not
possible.
Based on review of the Soilogic report, groundwater was measured (July 2018) in most borings across
the site at depths ranging from about 11-½ to 15 feet below the ground surface.
Based upon review of U.S. Geological Survey Maps (4Hillier, et al, 1979), regional groundwater beneath
the project area predominates in unconsolidated alluvial deposits at depths generally ranging from 10 to
20 feet below the ground surface.
ENGINEERING RECOMMENDATIONS
Geotechnical Considerations: The site appears suitable for the proposed construction as long as the
recommendations included herein are incorporated into the design and construction aspects of the
project. In our opinion, the primary geotechnical concerns with respect to the proposed development
are presented below.
• Existing Fills, Demolition, and Site Preparation: The existing development (existing buildings,
pavements, utilities, and flatwork, etc.) will be demolished and removed from the site as part of the
new development. Demolition and removal of these features will likely expose or generate soft or
loose soil conditions. Demolition should include removal of shallow foundations, underground
utilities, and mitigation of any loose or otherwise unsuitable backfill materials. Any unsuitable
existing fill soils should be removed and recompacted, where present below planned
improvements.
• Below-Grade Construction: Groundwater was measured in our borings at depths ranging from
about 13 to 18 feet below existing site grades, similar to those reported in the Soilogic geotechnical
study (July 2018) for the site at depths ranging from about 11-½ to 15 feet below the ground
surface. These measurements are only representative of groundwater conditions at the time
measured and may not be indicative of “high” groundwater elevation. Based on these
measurements, we do not believe that groundwater will limit normal construction of basement,
crawlspace, elevator pits or vaults on the site, if desired. However, we recommend that any
basement or other below-grade foundations bear a minimum of three feet above “seasonal high
groundwater elevation”. In addition, foundation drain systems will be required at the base of these
areas and behind any walls which retain more than 2 to 3 feet of earth (unless they are designed for
hydrostatic pressures).
4 Hillier, Donald E.; and Schneider, Paul A., Jr., 1979, Depth to Water Table (1976-1977) in the Boulder – Fort Collins – Greeley Area,
Front Range Urban Corridor, Colorado, United States Geological Survey, Map I-855-I.
Preliminary Geotechnical Engineering Report
Proposed Commercial or Mixed-Use Development – S. College Avenue & W. Drake Road, Fort Collins, CO
CGG Project No. 25.22.081
Cole Garner Geotechnical Page 6
Geotechnical Engineering and Materials Testing
• Structural Considerations: Field and laboratory data from samples obtained from our borings
suggest that the existing soils are low expansive at existing moisture contents; these soils should be
suitable for support of spread footing foundations and slab-on-grade floors provided that typical
movement can be tolerated. However, some soft soil conditions may be encountered and may
require mitigation to support new structural loads. Mitigation to provide for a stable base below
foundations and floor slabs typically includes limited subexcavation, moisture-conditioning, and
recompaction of any unsuitable materials to provide a relatively uniform thickness of approved
engineered fill below these elements. If heavily-loaded structures are planned for the site, the use
of deep foundations may be appropriate to support these loads and help limit foundation
movement.
• Future Additional Geotechnical Studies: The scope of services for this current study included a
general evaluation of subsurface conditions to identify main geotechnical issues or concerns that
may affect development of the project. Supplemental design-level geotechnical explorations, with
additional structure-specific borings will be required to develop design-level recommendations for
structures and to confirm and/or modify the preliminary recommendations and conclusions
contained in this report. In addition, formal pavement design studies for final design of any public
roadway improvements will be required.
Earthwork:
• General Considerations: The following presents recommendations for site preparation, excavation,
subgrade preparation and placement of engineered fills on the project.
All earthwork on the project should be observed and evaluated by CGG. The evaluation of earthwork
should include observation and testing of engineered fills, subgrade preparation, foundation bearing
soils and other geotechnical conditions exposed during the construction of the project.
• Demolition and Site Preparation: Strip and remove existing vegetation and other deleterious
materials from proposed building and pavement areas. All exposed surfaces should be free of
mounds and depressions that could prevent uniform compaction. Stripped materials consisting of
vegetation and organic materials should be wasted from the site or stockpiled for use in re-
vegetation of non-structural/landscaping areas.
Demolition of the existing development (i.e. existing foundations, floor slabs, pavements, exterior
flatwork, etc.) should include complete removal of all foundation elements within the proposed
construction area. Existing piers (if present) should be truncated a minimum of three feet below
new building foundations. Demolition should also include removal of any loose backfill found
adjacent to or below existing foundations or associated with underground utilities. All non-inert
materials derived from the demolition of existing structures should be removed from the site and
Preliminary Geotechnical Engineering Report
Proposed Commercial or Mixed-Use Development – S. College Avenue & W. Drake Road, Fort Collins, CO
CGG Project No. 25.22.081
Cole Garner Geotechnical Page 7
Geotechnical Engineering and Materials Testing
should not be allowed for use in any on-site fills without approval of the engineer. Site concrete may
be re-used on site, provided they are processed to a maximum size of 3 to 4 inches and blended into
the on-site soils at the discretion of the geotechnical engineer. It may be advantageous to stockpile
these materials and use them to stabilize any soft subgrade soils that may be encountered during
construction.
In our experience, the soils underlying existing improvements are often variable; based on our field
observations and test results, the soils to be exposed during demolition should be relatively stable.
However, unstable conditions, loose and/or soft fill soils may be encountered in isolated areas. Soil
stability may also be affected by precipitation, seasonal groundwater fluctuations, repetitive
construction traffic, or other factors. Additionally, soft, high-moisture content soils may be present
directly below existing pavements and flatwork. Where unstable conditions, if any, are encountered
or develop during construction, workability may be improved by scarifying and aeration during
warmer periods. In some areas, removal and recompaction (or replacement with other on-site soils)
may be suitable to build a stable base for placement of new fills.
In areas where subgrade soils are very soft/yielding (if any), gravel augmentation (mechanically
compacting/kneading crushed rock into the subgrade soils) may be cost-effective. In our experience,
crushed rock or recycled concrete materials on the order of 3 to 6 inches in size would be effective
in most situations. As an alternative, chemical treatment by blending fly ash, lime or Portland
cement into the subgrade could also be considered. The actual mitigation methods used should be
based on observation of exposed conditions by the geotechnical engineer.
• Subgrade Preparation: All subgrade soils at the base of subexcavations, below any new fill, slab-on-
grade floors, exterior PCC flatwork, and pavements should be scarified to a minimum depth of 12
inches, moisture conditioned and compacted as discussed below just prior to construction of these
elements.
• Fill Materials: Clean on-site soils or approved imported materials may be used as fill material. Other
imported soils used for general fill (if required) should conform to the following:
Percent finer by weight
Gradation (ASTM C136)
6” .................................................................................................................................... 100
3" ............................................................................................................................... 70-100
No. 4 Sieve ................................................................................................................. 50-100
No. 200 Sieve ........................................................................................................... 20 to 80
• Liquid Limit ........................................................................................................ 40 (max)
• Plasticity Index .................................................................................................. 20 (max)
• Maximum expansive potential (%)* ........................................................................... 0.5
Preliminary Geotechnical Engineering Report
Proposed Commercial or Mixed-Use Development – S. College Avenue & W. Drake Road, Fort Collins, CO
CGG Project No. 25.22.081
Cole Garner Geotechnical Page 8
Geotechnical Engineering and Materials Testing
*Measured on a sample compacted to approximately 95 percent of the ASTM D698 maximum
dry density at about optimum water content. The sample is confined under a 500 psf surcharge
and submerged.
• Fill Placement and Compaction: The on-site soils are suitable for use as fill on the site. These
materials should be processed with a maximum particle size of about 3 to 4 inches. Engineered fill
for site development, grading, and below foundations and floor slabs should be placed and
compacted in horizontal lifts, using equipment and procedures that will produce recommended
moisture contents and densities throughout the lift. Fill soils should be placed and compacted
according to the following criteria:
Criteria Recommended values
Lift Thickness 8 to 12 inches or less in loose thickness
Moisture Content Range
• Clayey soils: +1% to +4% above optimum moisture content
• Non-plastic granular soils: -2% below to +3% above optimum
• Pavement areas: Optimum to +2% above optimum
Compaction
Clayey soils: ASTM D698 standard Proctor dry density
• 95% minimum
Non-plastic granular soils: ASTM D1557 modified Proctor dry density
• 95% minimum
Earthwork contractors should use equipment and methods that ensure the soils are properly
processed with a relatively uniform distribution of added moisture, and adequate compaction
throughout each lift. We recommend that fill placement and compaction beneath foundations be
observed and tested by CGG on a full-time basis, unless modified by the geotechnical engineer.
At a minimum, fill soils placed for site grading, utility trench backfill, foundation backfill or sub-
excavation fill, and floor slab and PCC flatwork subgrade soils should be tested to confirm that
earthwork is being performed according to our recommendations and project specifications.
Subsequent lifts of fill should not be placed on previous lifts if the moisture content or dry density is
determined to be less than specified.
Fill should not be allowed to dry significantly prior to construction. Areas allowed to dry may
require additional preparation prior to construction of roadways, flatwork, foundations, et cetera.
• Excavation and Trench Construction: It is anticipated that excavations for the proposed
construction can be accomplished with conventional heavy-duty earthmoving equipment.
Excavations into the clays will likely stand on relatively steep temporary slopes; however, caving
sand soils are also present at the site. The individual contractor(s) should be made responsible for
designing and constructing stable, temporary excavations as needed to maintain stability of both
the excavation sides and bottom. All excavations should be sloped or shored in the interest of
Preliminary Geotechnical Engineering Report
Proposed Commercial or Mixed-Use Development – S. College Avenue & W. Drake Road, Fort Collins, CO
CGG Project No. 25.22.081
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Geotechnical Engineering and Materials Testing
safety following local and federal regulations, including current OSHA excavation and trench
safety standards. If excavations approach property lines, public right-of-way, or adjacent facilities
the contractor should assess the potential need to shore the sides of excavations.
Depending upon depth of excavation and seasonal conditions, groundwater may be encountered
in excavations on the site. Pumping from sumps may be utilized to control water within
excavations. Well points may be required for significant groundwater flow, or where excavations
penetrate groundwater to a significant depth. Dewatering permits may be required from the City
of Fort Collins and/or State.
The soils to be penetrated by the proposed excavations may vary significantly across the site. The
contractor should verify that similar conditions exist throughout the proposed area of excavation. If
different subsurface conditions are encountered at the time of construction, the actual conditions
should be evaluated to determine any excavation modifications necessary to maintain safe
conditions.
As a safety measure, it is recommended that all vehicles and soil piles be kept to a minimum lateral
distance from the crest of the slope equal to no less than the slope height. The exposed slope face
should be protected against the elements.
Conceptual Structural Considerations: Based on the subsurface conditions across the site and the
nature of the proposed structures, the site is suitable for foundation construction commonly used in the
region. Actual foundation designs should be based on additional design-level geotechnical exploration
and evaluation of the soil conditions for each structure.
• Structure Foundations: Provided any unsuitable soils (i.e. soft/loose) are mitigated below new
building areas, we believe that the use of spread footing foundations and slab-on-grade floors can
be considered with low risk of excessive movement. Preliminary foundation designs may be based
on a maximum bearing capacity of 1,500 to 2,500 pounds per square foot (psf) when bearing on a
zone of recompacted on-site soils or suitable native soils approved by the Geotechnical Engineer.
Foundations along exterior walls should bear a minimum of 36 inches below finished exterior grade
for frost protection. If heavily-loaded structures are planned for the site, the use of deep
foundations may be appropriate to support these loads and help limit foundation movement.
Building foundations should be designed based on future supplemental design-level geotechnical
investigations completed subsequent to mass site grading. This would be accomplished by
advancing a minimum of one to two borings per structure, as well as additional borings for
pavements. Additional evaluation will be used to provide site-specific criteria for final design of
foundations, pavements and other construction related elements of each structure.
Preliminary Geotechnical Engineering Report
Proposed Commercial or Mixed-Use Development – S. College Avenue & W. Drake Road, Fort Collins, CO
CGG Project No. 25.22.081
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Geotechnical Engineering and Materials Testing
• Below-Grade Construction: As discussed, groundwater was measured in our borings at depths
ranging from about 13 to 18 feet below existing site grades and in the Soilogic borings (July 2018) at
depths ranging from about 11-½ to 15 feet below the ground surface. Based on these
measurements, groundwater should not limit below-grade construction (i.e. normal basement,
crawlspace, pits/vaults) on the site, if desired. However, we recommend that the interior of any
basement bear a minimum of three feet above “seasonal high groundwater elevation”.
Foundation drain systems will be required at the base of these areas and behind any walls which
retain more than 2 to 3 feet of earth. Foundation drainage systems typically include perforated
pipe(s), embedded in gravel, placed in trenches that are sloped to discharge flows either into the
storm sewer system or to a sump pit inside the building where water could be pumped to a suitable
discharge.
• Interior Floor Slabs: Provided any unsuitable soils (if present) are removed and recompacted below
the building, we believe that interior (non-structural) slab-on-grade floors will likely provide
acceptable performance at the site.
Based on our experience, normal movement of unreinforced or lightly reinforced slab-on-grade
floors in the geologic region is considered to be about 1 to 2 inches, when bearing on approved low-
expansive native soils or moisture-conditioned and compacted engineered fill. If this degree of
movement cannot be tolerated, we recommend the use of a structural floor supported on the
foundation (over a crawlspace).
Typical precautions used to manage this movement include isolating plumbing and HVAC
equipment, providing void space beneath partition walls, proper construction of closely spaced
control joints, et cetera. Cosmetic distress such as drywall cracking, racking of door frames, etc. may
result from slab movement in finished spaces. These floor slab design and construction methods are
common in the region and final recommendations should be included in design-level geotechnical
studies.
Design of Private Pavements: Design of private pavements for the project is based on the procedures
outlined in the 1993 Guideline for Design of Pavement Structures by the American Association of State
Highway and Transportation Officials (AASHTO) and the Colorado Department of Transportation (CDOT) as
referenced by Commerce City standards. These design methods take into account several variables,
including subgrade soil and traffic conditions. We also referred to the Larimer County Urban Area Street
Standards (LCUASS), as adopted by the City of Fort Collins. If public roadway construction is to be included
in the project, additional geotechnical investigation and a formal pavement design will be required for
those improvements.
• Subgrade Soil: The near-surface materials at the site consist of lean clays with varying amounts of sand.
These clay soils are considered to provide poor pavement support. We estimated a design R-value of 5
for flexible pavement (asphalt) thickness design based on the properties of these materials.
Preliminary Geotechnical Engineering Report
Proposed Commercial or Mixed-Use Development – S. College Avenue & W. Drake Road, Fort Collins, CO
CGG Project No. 25.22.081
Cole Garner Geotechnical Page 11
Geotechnical Engineering and Materials Testing
Likewise, modulus of subgrade reaction (K-value) of 100 pounds per cubic inch (pci) was used for
design of rigid concrete pavements.
• Assumed Traffic – Private Pavements: We assume that pavements associated with the project will
include private drive lanes, driveways, fire lanes, and surface parking for automobiles and light trucks.
We assume that private pavements will be surfaced with either asphalt concrete or Portland cement
concrete. Any improvements to adjacent public roadways will need to be designed and constructed
according to the governing standards.
Based on our experience with similar projects, the following traffic criteria were used for
determining pavement thicknesses using a design life of 20 years:
• Driveways and parking stalls - maximum daily traffic of 1,000 cars per day (equivalent single-axle
loads, ESAL's of 22,000)
• Individual Lot site access drives and fire lanes – up to 5 trips/day by single-axle delivery trucks
per day, 1 combined-axle truck per day and 1 trash truck per day, 1 semi-tractor trailer per day,
plus maximum daily traffic of 1,000 cars per day (73,000 ESAL’s)
• Main site access drives and fire lanes – up to 30 trips/day by single-axle delivery trucks per day,
1 combined-axle truck per day and 1 trash truck per day, 5 semi-tractor trailers per day,
occasional fire truck traffic (85,000 pounds maximum), plus maximum daily traffic of 3,000 cars
per day (365,000 ESAL’s – LCUASS Roadway Classification - Local Commercial)
The owner and other design professionals should review these assumptions to be sure that the
pavement sections will be sufficient for anticipated traffic over the life of the project. We are
available to review the recommended sections based on actual anticipated traffic, upon request.
• Pavement Sections: For flexible pavement design, a terminal serviceability index of 2.3 was utilized
along with an inherent reliability of 75 percent and a design life of 20 years. Using a design R-value
of 5, the appropriate ESAL values, environmental criteria and other factors, the structural numbers
(SN) of the pavement sections were determined on the basis of the 1993 AASHTO design equation.
In addition to the flexible pavement design analyses, a rigid pavement design analysis was
completed based upon AASHTO design procedures. Along with soil and traffic conditions, rigid
pavement design is based on the Modulus of Rupture of the concrete, and other factors previously
outlined. A modulus of rupture of 650 psi (working stress 488 psi) was used for pavement concrete.
The rigid pavement thickness for each traffic category was determined on the basis of the AASHTO
design equation.
We have considered full depth-asphalt paving, a composite section with asphalt concrete over
aggregate base course, and full depth rigid concrete sections. Alternatives for flexible and rigid
pavements are summarized for each traffic area as follows:
Preliminary Geotechnical Engineering Report
Proposed Commercial or Mixed-Use Development – S. College Avenue & W. Drake Road, Fort Collins, CO
CGG Project No. 25.22.081
Cole Garner Geotechnical Page 12
Geotechnical Engineering and Materials Testing
Recommended alternatives for flexible and rigid pavements are summarized for each traffic area as
shown below. Pavement section ranges (as shown) for individual lots are preliminary and should be
provided with additional design-level geotechnical exploration. Design-level pavement thickness
recommendations are also provided below for main drives used to access lots.
Traffic Area Alternative
Preliminary Pavement Thickness (Inches)
Hot-Mix Asphalt
(HMA)
Aggregate Base
Course
(ABC)
Portland Cement
Concrete
(PCC)
Light-Duty (Lots)
Automobile and Light Truck
Parking Only
HMA + ABC 3-½ to 4 6 to 8 --
HMA 5-½ to 6 -- --
PCC -- -- 5
Heavy-Duty (Lots)
Private Drives, Fire Lanes,
Delivery truck access
HMA + ABC 4-½ to 5 6 to 8 --
HMA 6-½ to 7 -- --
PCC -- -- 6
Main Access Drives
Design-Level Pavement Thickness (Inches)
HMA + ABC 5-½ 10 --
PCC -- -- 7
Each alternative should be investigated with respect to current material availability and economic
conditions. Pavement thicknesses recommended are based on approved subgrade materials being
properly moisture conditioned and compacted prior to paving.
For areas subject to concentrated and repetitive loading conditions such as dumpster pads, and
ingress/egress aprons, we recommend using a Portland cement concrete pavement with a
thickness of at least 6 inches. For dumpster pads, the concrete pavement area should be large
enough to support the container and tipping axle of the refuse truck.
• Temporary Unpaved Access Drives: In our opinion, the use of aggregate base course or crushed
stone may be considered for use in constructing temporary access roads for construction traffic
and/or all-weather fire truck access. In order to provide an all-weather surface, we recommend that
the section include a minimum of 12 inches of aggregate base course (CDOT Class 5 or 6) or a
minimum of 8 inches of 3-inch minus crushed aggregate (or recycled concrete). In our opinion, these
sections would be suitable for the support of delivery and concrete trucks and occasional fire truck
access (85,000 pounds maximum) for the anticipated duration of a typical project of this magnitude.
The contractor should be responsible for monitoring the condition of unpaved drive lanes, including
the repair and maintenance of the drive lanes throughout its use in order to provide the required
access. We believe it is likely that these aggregate materials will be “contaminated” with soil and
other constituents over the course of construction; therefore, the aggregate materials should not be
considered part of the final pavement section unless otherwise evaluated and approved by the
Preliminary Geotechnical Engineering Report
Proposed Commercial or Mixed-Use Development – S. College Avenue & W. Drake Road, Fort Collins, CO
CGG Project No. 25.22.081
Cole Garner Geotechnical Page 13
Geotechnical Engineering and Materials Testing
Geotechnical Engineer.
• Subgrade Preparation: We recommend the pavement areas be rough graded and then thoroughly
proof rolled with a loaded tandem axle dump truck, water truck, or other heavy equipment
approved by the observing engineer prior to final grading and paving. Particular attention should be
paid to high traffic areas that were rutted and disturbed earlier and to areas where backfilled
trenches are located. Areas where unsuitable conditions are located should be repaired by
removing and replacing the materials with properly compacted engineered fills.
At a minimum, in order to provide a more uniform subgrade for site pavements, we recommend
that all pavements be constructed on a minimum of 12 inches of properly moisture conditioned
and recompacted on-site soils. Confirmation of the moisture content and compaction level of the
subgrade soils should be confirmed within 24 hours prior to paving.
• Pavement Materials: Materials utilized for pavements should meet specifications outlined in the
CDOT and LCUASS Standards. Aggregate base course (if used on the site) should consist of a blend
of sand and gravel that meets strict specifications for quality and gradation. Use of materials
meeting Colorado Department of Transportation (CDOT) Class 5 or 6 specifications is recommended
for base course. Aggregate base course should be placed in lifts not exceeding 6 inches and
compacted to a minimum of 95 percent of the standard Proctor density (ASTM D698).
Hot-mix asphalt (HMA) should be composed of a mixture of aggregate, filler and additives (if
required) and approved bituminous material. HMA should conform to approved mix designs stating
the Hveem properties, optimum asphalt content, and job mix formula and recommended mixing
and placing temperatures. Aggregate used in hot-mix asphalt should meet particular gradations.
Material meeting CDOT Grading S, SG (bottom-lift only) or SX (top-lift only) specifications or
equivalent is recommended for HMA. Mix designs should be submitted prior to construction to
verify their adequacy. HMA should be placed in appropriate lifts (CDOT specs per table below) and
compacted within a range of 92 to 96 percent of the theoretical maximum (Rice) density (ASTM
D2041).
CDOT specifications for asphalt pavement lift thickness are summarized below based on mix
aggregate size:
CDOT HMA Grade Nominal Maximum
Aggregate Size
Structural Layer Lift Thickness (Inches)
Minimum Maximum
SX 1/2“ 2.00 3.00
S 3/4” 2.25 3.50
SG 1” 3.00 4.00
* Alternative lift thicknesses can be considered provided the contractor uses equipment and
procedures to obtain the required compaction.
Preliminary Geotechnical Engineering Report
Proposed Commercial or Mixed-Use Development – S. College Avenue & W. Drake Road, Fort Collins, CO
CGG Project No. 25.22.081
Cole Garner Geotechnical Page 14
Geotechnical Engineering and Materials Testing
Concrete utilized for rigid pavements should meet CDOT Class P requirements and be obtained from
an approved mix design with the following minimum properties:
• Modulus of Rupture @ 28 days ............................................................................. 650 psi minimum
• Strength Requirements ..................................................................................................... ASTM C94
• Cement Type ............................................................................................................ Type II Portland
• Entrained Air Content ............................................................................................................ 6 to 8%
• Concrete Aggregate ...................................................................... ASTM C33 and CDOT Section 703
Concrete should be deposited by truck mixers or agitators and placed a maximum of 90 minutes
from the time the water is added to the mix. Other specifications outlined by CDOT should be
followed.
Longitudinal and transverse joints should be provided as needed in concrete pavements for
expansion/contraction and isolation. The location and extent of joints should be based upon the
final pavement geometry. Sawed joints should be cut within 24 hours of concrete placement and
should be a minimum of 25 percent of slab thickness plus 1/4 inch. All joints should be sealed to
prevent entry of foreign material and doweled where necessary for load transfer.
• Pavement Performance: Future performance of pavements constructed on the subgrade at this site
will be dependent upon several factors, including:
• Maintaining stable moisture content of the subgrade soils.
• Providing for a planned program of preventative maintenance.
The performance of all pavements can be enhanced by minimizing excess moisture, which can reach
the subgrade soils. The following recommendations should be considered at minimum:
• Site grading at a minimum 2 percent grade onto or away from pavements.
• Water should not be allowed to pond behind curbs.
• Compaction of any utility trenches for landscaped areas to the same criteria as the
pavement subgrade.
• Sealing all landscaped areas in or adjacent to pavements to minimize or prevent moisture
migration to subgrade soils.
• Placing compacted backfill against the exterior side of curb and gutter.
• Placing curb, gutter and/or sidewalk directly on subgrade soils without the use of base
course materials.
Preliminary Geotechnical Engineering Report
Proposed Commercial or Mixed-Use Development – S. College Avenue & W. Drake Road, Fort Collins, CO
CGG Project No. 25.22.081
Cole Garner Geotechnical Page 15
Geotechnical Engineering and Materials Testing
Preventative maintenance should be planned and provided for an ongoing pavement management
program in order to enhance future pavement performance. Preventative maintenance activities
are intended to slow the rate of pavement deterioration and to preserve the pavement investment.
Preventative maintenance consists of both localized maintenance (e.g. crack sealing and patching)
and global maintenance (e.g. surface sealing). Preventative maintenance is usually the first priority
when implementing a planned pavement maintenance program and provides the highest return on
investment for pavements.
Final Grading, Landscaping, and Surface Drainage: All grades must be adjusted to provide positive
drainage away from structures during construction and maintained throughout the life of the proposed
project. Water permitted to pond near or adjacent to the perimeter of the structures (either during or
post-construction) can result in significantly higher soil movements than those discussed in this report.
As a result, any estimations of potential movement described in this report cannot be relied upon if
positive drainage is not obtained and maintained, and water is allowed to infiltrate the fill and/or
subgrade. Infiltration of water into utility or foundation excavations must be prevented during
construction.
We recommend that exposed ground (unpaved areas) be sloped at a minimum of 10 percent grade for
at least 10 feet beyond the perimeter of the buildings, where possible. We understand that this may
not be feasible in all unpaved areas due to ADA access requirements and other required design features.
In these areas, exterior grades should be sloped as much as possible down to area drain systems, swales,
and/or sidewalk chases to facilitate drainage. In all cases, the grade should slope a minimum of 5
percent away from structures in accordance with the applicable building code.
Downspouts should also be connected to area drain systems to help reduce wetting, if possible. If this
is not possible, roof drain flows should be directed onto pavements or discharge a minimum of 5 feet
away from the structure a through the use of splash blocks or downspout extensions.
Backfill against foundations, exterior walls and in utility and sprinkler line trenches should be well
compacted and free of all construction debris to reduce the possibility of moisture infiltration. After
building construction and prior to project completion, we recommend that verification of final grading
be performed to document that positive drainage, as described above, has been achieved. This is
especially important in areas where heating and cooling units are placed in close proximity to the
buildings.
Landscaped irrigation adjacent to foundations should be eliminated where possible or minimized to
only limited drip irrigation. Sprinkler mains and spray heads should be located a minimum of 5 feet
away from the buildings. We recommend the use of Xeric landscaping, requiring little or no irrigation,
be used within 5 feet of foundations. If drip irrigation is required in this zone, systems should be timed
to provide only the amount of water needed to sustain growth. Irrigation systems should be frequently
Preliminary Geotechnical Engineering Report
Proposed Commercial or Mixed-Use Development – S. College Avenue & W. Drake Road, Fort Collins, CO
CGG Project No. 25.22.081
Cole Garner Geotechnical Page 16
Geotechnical Engineering and Materials Testing
checked for proper performance and any breakages fixed as soon as possible. Planters located adjacent
to the structure should preferably be self-contained (planter boxes, potted landscaping, etc.), if possible.
Additional Design and Construction Considerations:
• Exterior Slab Design and Construction: Flatwork and pavements will be subject to post
construction movement due to backfill settlement and/or soil/frost heave. In our experience, it is
not feasible to eliminate the potential for movement of exterior flatwork. The amount of
movement will be related to the compactive effort used when the fill soils are placed and future
wetting of the subgrade soils. The potential for damage would be greatest where exterior slabs are
constructed adjacent to the building or other structural elements.
To reduce the potential for damage, we recommend:
• exterior slabs in critical areas be supported on a zone of recompacted soils as recommended
for pavement areas.
• supporting of flatwork at building entrances and other critical areas on haunches attached
by the building foundations.
• placement of effective control joints on relatively close centers and isolation joints between
slabs and other structural elements.
• provision for adequate drainage in areas adjoining the slabs.
• use of designs which allow vertical movement between the exterior slabs and adjoining
structural elements.
• Underground Utility Systems: All underground utility lines penetrating below foundations should be
installed deep enough to avoid direct contact with foundations or be designed with flexible
couplings (if available), so minor deviations in alignment do not result in breakage or distress. Utility
knockouts in foundation walls should be oversized to accommodate differential movements.
It is strongly recommended that a representative of the geotechnical engineer provide full-time
observation and compaction testing of trench backfill within building and pavement areas.
• Concrete Corrosion Protection: Select samples were tested for the presence of water-soluble
sulfates, as outlined in the table below.
Boring Depth
(ft) Material Water-Soluble
Sulfates (ppm)
ACI Sulfate
Exposure Class
1 4 Sandy Lean Clay 0 S0
4 4 Lean Clay with Sand 0 S0
P2 2 Lean Clay 0 S0
Preliminary Geotechnical Engineering Report
Proposed Commercial or Mixed-Use Development – S. College Avenue & W. Drake Road, Fort Collins, CO
CGG Project No. 25.22.081
Cole Garner Geotechnical Page 17
Geotechnical Engineering and Materials Testing
The select samples, likely to be in contact with project concrete, were tested for the presence of
water-soluble sulfates in order to determine corrosion characteristics and the appropriate concrete
mixture. Results of testing indicate the samples are within the American Concrete Institute (ACI)
Sulfate Exposure Class S0. However, for increased protection from concrete sulfate attack, we
recommend project concrete be designed utilizing ACI Sulfate Exposure Class S1, in accordance
with Chapter 19 of the ACI design manual, Building Code Requirements for Structural Concrete
(ACI 318-14), as summarized in the table below.
ACI Sulfate
Exposure Class
Portland Cement Type
(ASTM C150)
Maximum
Water/Cement Ratio
Minimum Concrete
Compressive Strength
(psi)
S1 II (or equivalent) 0.50 4,000
• Future Additional Geotechnical Studies: The scope of services for this current study included a
general evaluation of subsurface conditions in order to identify main geotechnical issues or concerns
that may affect development of the project. Supplemental design-level geotechnical explorations,
with additional structure-specific borings will be required in order to develop design-level
recommendations for structures and to confirm and/or modify the preliminary recommendations
and conclusions contained in this report. In addition, formal pavement design studies for final
design of any public roadway improvements will be required.
GENERAL COMMENTS
The scope of services for this current study included a general evaluation of subsurface conditions in
order to identify main geotechnical issues or concerns that may affect land development. Supplemental
design-level geotechnical exploration(s), with additional structure-specific borings will be required in
order to develop design-level recommendations for structures and to confirm and/or modify the
recommendations and conclusions contained in this report. In addition, formal pavement design
studies will be required for final design of all public roads.
CGG should be retained to review the final design plans and specifications so comments can be made
regarding interpretation and implementation of our geotechnical recommendations in the design and
specifications. CGG should also be retained to provide testing and observation during the excavation,
grading, foundation and construction phases of the project.
The analysis and recommendations presented in this report are based upon the data obtained from the
borings performed at the indicated locations and from other information discussed in this report. This
report does not reflect variations that may occur between borings, across the site, or due to the
modifying effects of weather. The nature and extent of such variations may not become evident until
during or after construction. If variations appear, we should be immediately notified so that further
evaluation and supplemental recommendations can be provided.
Preliminary Geotechnical Engineering Report
Proposed Commercial or Mixed-Use Development – S. College Avenue & W. Drake Road, Fort Collins, CO
CGG Project No. 25.22.081
Cole Garner Geotechnical Page 18
Geotechnical Engineering and Materials Testing
The scope of services for this project does not include, either specifically or by implication, any
environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or
prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the
potential for such contamination or pollution, other studies should be undertaken.
This report has been prepared for the exclusive use of our client for specific application to the project
discussed and has been prepared in accordance with generally accepted geotechnical engineering
practices. No warranties, either express or implied, are intended or made. Site safety, excavation
support, and dewatering requirements are the responsibility of others. In the event that changes are
planned in the nature, design, or location of the project as outlined in this report, the conclusions and
recommendations contained in this report shall not be considered valid unless CGG reviews the
changes, and either verifies or modifies the conclusions of this report in writing.
APPENDIX A
BORING LOCATION DIAGRAM
BORING LOGS
APPROXIMATE BORING LOCATIONS
Cole Garner Geotechnical
1070 W. 124th Ave., Suite 300
Westminster, CO 80234
(303) 996-2999
1
FIGURE 1 - BORING LOCATION DIAGRAM
PROPOSED COMMERCIAL/MIXED-USE DEVELOPMENT
SWC of W. DRAKE ROAD and S. COLLEGE AVENUE
FORT COLLINS, COLORADO
CGG PROJECT NO. 25.22.081
2
3
4
P1
P2
P3
P4
CB
CB
CB
CB
CB
CL
CL
CL
CL
CL
13 / 12
10 / 12
18 / 12
22 / 12
10 / 12
104
108
121
107
+0.4/500
+0.2/500
+0.3/1000
20.6
18.8
13.3
20.5
100
100
100
0
100
SANDY LEAN CLAY, varies with gravel, brown to dark brown,
reddish-brown, olive-brown, moist to wet, medium stiff to very stiff
Approximate bottom of borehole at 25.0 feet.
25
DRILLING METHOD CME-55 / Solid Stem Auger
DATE STARTED 6/6/25
GROUND WATER LEVELS:
SURFACE CONDITIONS Approx. 4" asphalt over 6" ABCDRILLING CONTRACTOR Vine Laboratories
COMPLETED 6/6/25
LOGGED BY AL CHECKED BY AG
HAMMER TYPE Automatic
PROPOSED ELEV.Not Provided
DURING DRILLING 18.00 ft - 6/6/25
AFTER DRILLING Backfilled & patched - 6/6/25
GROUND SURFACE ELEV.Not Provided
SA
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(f
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MATERIAL DESCRIPTION
PAGE 1 OF 1
BORING NUMBER 1
CLIENT Kentro Group
PROJECT NUMBER 25.22.081
PROJECT NAME Proposed Commercial or Mixed-Use Development
PROJECT LOCATION S. College Ave & W. Drake Rd - Fort Collins, CO
GE
O
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Cole Garner Geotechnical1070 W 124th Ave, Suite 300Westminster, CO 80234
CB
CB
CB
CB
CB
CB
CB
CL
SC-SM
CL
CL
CL
SC/SM
-
5 / 12
10 / 12
8 / 12
12 / 12
6 / 12
12 / 12
50 / 1
111
132
112
120
116
127
-0.3/500
-0.5/1000
16.4
9.1
17.7
17.5
18.3
13.7
18.5
100
100
100
100
100
100
100
SANDY LEAN CLAY, brown to dark brown, reddish-brown,
moist, soft
CLAYEY to SILTY SAND, fine- to medium-grained, some
coarse, reddish-brown, brown, dry to moist, loose
SANDY LEAN CLAY, varies to Clayey Sand, brown,
reddish-brown, iron-stained, calcareous, moist to wet, medium
stiff to stiff
CLAYEY to SILTY SAND, fine- to medium-grained, light brown
to brown, olive-brown, grey, moist to wet, loose
SANDSTONE BEDROCK, fine- to medium-grained, varies
clayey, brown, tan, olive-brown, moist, very hard
Approximate bottom of borehole at 35.0 feet.
6
11
27
30
35
DRILLING METHOD CME-55 / Solid Stem Auger
DATE STARTED 6/6/25
GROUND WATER LEVELS:
SURFACE CONDITIONS Approx. 3" asphalt over 6" ABCDRILLING CONTRACTOR Vine Laboratories
COMPLETED 6/6/25
LOGGED BY AL CHECKED BY AG
HAMMER TYPE Automatic
PROPOSED ELEV.Not Provided
DURING DRILLING 18.00 ft - 6/6/25
AFTER DRILLING Backfilled & patched - 6/6/25
GROUND SURFACE ELEV.Not Provided
SA
M
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MATERIAL DESCRIPTION
PAGE 1 OF 1
BORING NUMBER 2
CLIENT Kentro Group
PROJECT NUMBER 25.22.081
PROJECT NAME Proposed Commercial or Mixed-Use Development
PROJECT LOCATION S. College Ave & W. Drake Rd - Fort Collins, CO
GE
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A
I
N
T
R
A
N
S
F
E
R
1
0
.
2
8
\
P
R
O
J
E
C
T
S
G
E
O
2
0
2
5
\
2
5
.
2
2
.
0
8
1
C
O
L
L
E
G
E
A
N
D
D
R
A
K
E
P
R
E
L
I
M
.
G
P
J
Cole Garner Geotechnical1070 W 124th Ave, Suite 300Westminster, CO 80234
CB
CB
CB
CB
CB
CB
CL
CL
CL
CL
CL
-
13 / 12
18 / 12
18 / 12
12 / 12
17 / 12
50 / 5
102
130
117
123
115
119
+0.6/500
-0.4/500
23.5
10.2
16.9
18.0
19.6
15.9
100
100
100
100
100
100
LEAN CLAY with SAND, varies to Sandy Lean Clay, light brown
to brown, reddish-brown, olive-brown, calcareous, iron-stained,
moist to wet, stiff to very stiff
SANDSTONE BEDROCK, fine- to medium-grained, varies
clayey, light brown, olive-brown, iron-stained, moist, very hard
Approximate bottom of borehole at 40.0 feet.
36
40
DRILLING METHOD CME-55 / Solid Stem Auger
DATE STARTED 6/6/25
GROUND WATER LEVELS:
SURFACE CONDITIONS Approx. 6" asphalt over 6" ABCDRILLING CONTRACTOR Vine Laboratories
COMPLETED 6/6/05
LOGGED BY AL CHECKED BY AG
HAMMER TYPE Automatic
PROPOSED ELEV.Not Provided
DURING DRILLING 13.00 ft - 6/6/25
AFTER DRILLING Backfilled & patched - 6/6/25
GROUND SURFACE ELEV.Not Provided
SA
M
P
L
E
T
Y
P
E
US
C
S
S
Y
M
B
O
L
GR
A
P
H
I
C
LO
G
DE
P
T
H
(f
t
)
0
5
10
15
20
25
30
35
40
PE
N
E
T
R
A
T
I
O
N
bl
o
w
s
/
i
n
DR
Y
U
N
I
T
W
T
.
(p
c
f
)
SW
E
L
L
-
C
O
N
S
O
L
/S
U
R
C
H
A
R
G
E
LO
A
D
,
%
p
s
f
MO
I
S
T
U
R
E
CO
N
T
E
N
T
(
%
)
RE
C
O
V
E
R
Y
%
MATERIAL DESCRIPTION
PAGE 1 OF 1
BORING NUMBER 3
CLIENT Kentro Group
PROJECT NUMBER 25.22.081
PROJECT NAME Proposed Commercial or Mixed-Use Development
PROJECT LOCATION S. College Ave & W. Drake Rd - Fort Collins, CO
GE
O
T
E
C
H
B
H
C
O
L
U
M
N
S
-
G
I
N
T
S
T
D
U
S
L
A
B
.
G
D
T
-
6
/
3
0
/
2
5
1
3
:
4
9
-
Y
:
\
G
I
N
T
B
A
C
K
U
P
S
\
M
A
I
N
T
R
A
N
S
F
E
R
1
0
.
2
8
\
P
R
O
J
E
C
T
S
G
E
O
2
0
2
5
\
2
5
.
2
2
.
0
8
1
C
O
L
L
E
G
E
A
N
D
D
R
A
K
E
P
R
E
L
I
M
.
G
P
J
Cole Garner Geotechnical1070 W 124th Ave, Suite 300Westminster, CO 80234
CB
CB
CB
CB
CB
CB
CL
CL/SC
CL
CL
CL
-
8 / 12
13 / 12
7 / 12
12 / 12
19 / 12
50 / 4
97
113
120
122
-1.0/500
-3.5/1000
24.6
11.1
18.2
18.0
16.7
16.5
100
100
100
100
100
100
LEAN CLAY with SAND, brown, calcareous, moist, medium
stiff
SANDY LEAN CLAY to CLAYEY SAND, reddish-brown, brown,
moist, stiff
SANDY LEAN CLAY, some gravel, reddish-brown, light brown
to brown, olive-brown, calcareous, moist to wet, medium stiff to
very stiff
SANDSTONE BEDROCK, fine-grained, light brown to brown,
grey, iron-stained, moist, very hard
Approximate bottom of borehole at 35.0 feet.
5
10
33
35
DRILLING METHOD CME-55 / Solid Stem Auger
DATE STARTED 6/6/25
GROUND WATER LEVELS:
SURFACE CONDITIONS Approx. 4" asphalt over 6" ABCDRILLING CONTRACTOR Vine Laboratories
COMPLETED 6/6/25
LOGGED BY AL CHECKED BY AG
HAMMER TYPE Automatic
PROPOSED ELEV.Not Provided
DURING DRILLING 13.00 ft - 6/6/25
AFTER DRILLING 8' DCI - 6/26/25
GROUND SURFACE ELEV.Not Provided
SA
M
P
L
E
T
Y
P
E
US
C
S
S
Y
M
B
O
L
GR
A
P
H
I
C
LO
G
DE
P
T
H
(f
t
)
0
5
10
15
20
25
30
35
PE
N
E
T
R
A
T
I
O
N
bl
o
w
s
/
i
n
DR
Y
U
N
I
T
W
T
.
(p
c
f
)
SW
E
L
L
-
C
O
N
S
O
L
/S
U
R
C
H
A
R
G
E
LO
A
D
,
%
p
s
f
MO
I
S
T
U
R
E
CO
N
T
E
N
T
(
%
)
RE
C
O
V
E
R
Y
%
MATERIAL DESCRIPTION
PAGE 1 OF 1
BORING NUMBER 4
CLIENT Kentro Group
PROJECT NUMBER 25.22.081
PROJECT NAME Proposed Commercial or Mixed-Use Development
PROJECT LOCATION S. College Ave & W. Drake Rd - Fort Collins, CO
GE
O
T
E
C
H
B
H
C
O
L
U
M
N
S
-
G
I
N
T
S
T
D
U
S
L
A
B
.
G
D
T
-
6
/
3
0
/
2
5
1
3
:
4
9
-
Y
:
\
G
I
N
T
B
A
C
K
U
P
S
\
M
A
I
N
T
R
A
N
S
F
E
R
1
0
.
2
8
\
P
R
O
J
E
C
T
S
G
E
O
2
0
2
5
\
2
5
.
2
2
.
0
8
1
C
O
L
L
E
G
E
A
N
D
D
R
A
K
E
P
R
E
L
I
M
.
G
P
J
Cole Garner Geotechnical1070 W 124th Ave, Suite 300Westminster, CO 80234
CB
CB
CB
CL/SC
CL
CL/SC
4 / 12
3 / 12
12 / 12
112
134
-0.4/500
11.9
16.2
11.7
100
100
100
FILL - SANDY LEAN CLAY to CLAYEY SAND, dark brown to
brown, reddish-brown, calcareous, moist, soft
SANDY LEAN CLAY to CLAYEY SAND, brown, reddish-brown,
calcareous, moist, stiff
Approximate bottom of borehole at 10.0 feet.
5
10
DRILLING METHOD CME-55 / Solid Stem Auger
DATE STARTED 6/6/25
GROUND WATER LEVELS:
SURFACE CONDITIONS Approx. 6" asphalt pavementDRILLING CONTRACTOR Vine Laboratories
COMPLETED 6/6/25
LOGGED BY AL CHECKED BY AG
HAMMER TYPE Automatic
PROPOSED ELEV.Not Provided
DURING DRILLING None - 6/6/25
AFTER DRILLING Backfilled & patched - 6/6/25
GROUND SURFACE ELEV.Not Provided
SA
M
P
L
E
T
Y
P
E
US
C
S
S
Y
M
B
O
L
GR
A
P
H
I
C
LO
G
DE
P
T
H
(f
t
)
0
5
10
PE
N
E
T
R
A
T
I
O
N
bl
o
w
s
/
i
n
DR
Y
U
N
I
T
W
T
.
(p
c
f
)
SW
E
L
L
-
C
O
N
S
O
L
/S
U
R
C
H
A
R
G
E
LO
A
D
,
%
p
s
f
MO
I
S
T
U
R
E
CO
N
T
E
N
T
(
%
)
RE
C
O
V
E
R
Y
%
MATERIAL DESCRIPTION
PAGE 1 OF 1
BORING NUMBER P1
CLIENT Kentro Group
PROJECT NUMBER 25.22.081
PROJECT NAME Proposed Commercial or Mixed-Use Development
PROJECT LOCATION S. College Ave & W. Drake Rd - Fort Collins, CO
GE
O
T
E
C
H
B
H
C
O
L
U
M
N
S
-
G
I
N
T
S
T
D
U
S
L
A
B
.
G
D
T
-
6
/
3
0
/
2
5
1
3
:
4
9
-
Y
:
\
G
I
N
T
B
A
C
K
U
P
S
\
M
A
I
N
T
R
A
N
S
F
E
R
1
0
.
2
8
\
P
R
O
J
E
C
T
S
G
E
O
2
0
2
5
\
2
5
.
2
2
.
0
8
1
C
O
L
L
E
G
E
A
N
D
D
R
A
K
E
P
R
E
L
I
M
.
G
P
J
Cole Garner Geotechnical1070 W 124th Ave, Suite 300Westminster, CO 80234
CB
CB
CB
CL
CL
SC
8 / 12
7 / 12
22 / 12
106
97
138
+0.3/20017.4
24.7
8.4
100
100
100
LEAN CLAY with SAND, varies with gravel, brown, calcareous,
moist, medium stiff
CLAYEY SAND, fine- to medium-grained, some gravel,
reddish-brown, brown, calcareous, dry to moist, medium dense
Approximate bottom of borehole at 10.0 feet.
6
10
DRILLING METHOD CME-55 / Solid Stem Auger
DATE STARTED 6/6/25
GROUND WATER LEVELS:
SURFACE CONDITIONS Approx. 4" asphalt over 4" ABCDRILLING CONTRACTOR Vine Laboratories
COMPLETED 6/6/25
LOGGED BY AL CHECKED BY AG
HAMMER TYPE Automatic
PROPOSED ELEV.Not Provided
DURING DRILLING None - 6/6/25
AFTER DRILLING Backfilled & patched - 6/6/25
GROUND SURFACE ELEV.Not Provided
SA
M
P
L
E
T
Y
P
E
US
C
S
S
Y
M
B
O
L
GR
A
P
H
I
C
LO
G
DE
P
T
H
(f
t
)
0
5
10
PE
N
E
T
R
A
T
I
O
N
bl
o
w
s
/
i
n
DR
Y
U
N
I
T
W
T
.
(p
c
f
)
SW
E
L
L
-
C
O
N
S
O
L
/S
U
R
C
H
A
R
G
E
LO
A
D
,
%
p
s
f
MO
I
S
T
U
R
E
CO
N
T
E
N
T
(
%
)
RE
C
O
V
E
R
Y
%
MATERIAL DESCRIPTION
PAGE 1 OF 1
BORING NUMBER P2
CLIENT Kentro Group
PROJECT NUMBER 25.22.081
PROJECT NAME Proposed Commercial or Mixed-Use Development
PROJECT LOCATION S. College Ave & W. Drake Rd - Fort Collins, CO
GE
O
T
E
C
H
B
H
C
O
L
U
M
N
S
-
G
I
N
T
S
T
D
U
S
L
A
B
.
G
D
T
-
6
/
3
0
/
2
5
1
3
:
4
9
-
Y
:
\
G
I
N
T
B
A
C
K
U
P
S
\
M
A
I
N
T
R
A
N
S
F
E
R
1
0
.
2
8
\
P
R
O
J
E
C
T
S
G
E
O
2
0
2
5
\
2
5
.
2
2
.
0
8
1
C
O
L
L
E
G
E
A
N
D
D
R
A
K
E
P
R
E
L
I
M
.
G
P
J
Cole Garner Geotechnical1070 W 124th Ave, Suite 300Westminster, CO 80234
CB
CB
CB
CL
CL
SC
10 / 12
9 / 12
9 / 12
98
131
+0.5/20022.9
17.1
10.3
100
100
100
LEAN CLAY with SAND, varies with gravel, brown,
reddish-brown, calcareous, moist, medium stiff
CLAYEY SAND, fine- to medium-grained, some gravel, varies
to Sandy Lean Clay, brown, reddish-brown, moist, loose
Approximate bottom of borehole at 10.0 feet.
6
10
DRILLING METHOD CME-55 / Solid Stem Auger
DATE STARTED 6/6/25
GROUND WATER LEVELS:
SURFACE CONDITIONS Approx. 2" asphalt over 4" ABCDRILLING CONTRACTOR Vine Laboratories
COMPLETED 6/6/25
LOGGED BY AL CHECKED BY AG
HAMMER TYPE Automatic
PROPOSED ELEV.Not Provided
DURING DRILLING None - 6/6/25
AFTER DRILLING Backfilled & patched - 6/6/25
GROUND SURFACE ELEV.Not Provided
SA
M
P
L
E
T
Y
P
E
US
C
S
S
Y
M
B
O
L
GR
A
P
H
I
C
LO
G
DE
P
T
H
(f
t
)
0
5
10
PE
N
E
T
R
A
T
I
O
N
bl
o
w
s
/
i
n
DR
Y
U
N
I
T
W
T
.
(p
c
f
)
SW
E
L
L
-
C
O
N
S
O
L
/S
U
R
C
H
A
R
G
E
LO
A
D
,
%
p
s
f
MO
I
S
T
U
R
E
CO
N
T
E
N
T
(
%
)
RE
C
O
V
E
R
Y
%
MATERIAL DESCRIPTION
PAGE 1 OF 1
BORING NUMBER P3
CLIENT Kentro Group
PROJECT NUMBER 25.22.081
PROJECT NAME Proposed Commercial or Mixed-Use Development
PROJECT LOCATION S. College Ave & W. Drake Rd - Fort Collins, CO
GE
O
T
E
C
H
B
H
C
O
L
U
M
N
S
-
G
I
N
T
S
T
D
U
S
L
A
B
.
G
D
T
-
6
/
3
0
/
2
5
1
3
:
4
9
-
Y
:
\
G
I
N
T
B
A
C
K
U
P
S
\
M
A
I
N
T
R
A
N
S
F
E
R
1
0
.
2
8
\
P
R
O
J
E
C
T
S
G
E
O
2
0
2
5
\
2
5
.
2
2
.
0
8
1
C
O
L
L
E
G
E
A
N
D
D
R
A
K
E
P
R
E
L
I
M
.
G
P
J
Cole Garner Geotechnical1070 W 124th Ave, Suite 300Westminster, CO 80234
CB
CB
CB
CL
CL
CL
9 / 12
7 / 12
5 / 12
104
123
119
+0.6/20021.8
16.0
15.2
100
100
100
SANDY LEAN CLAY, varies to Clayey Sand, brown to dark
brown, reddish-brown, moist, soft to medium stiff
Approximate bottom of borehole at 10.0 feet.
10
DRILLING METHOD CME-55 / Solid Stem Auger
DATE STARTED 6/6/25
GROUND WATER LEVELS:
SURFACE CONDITIONS Approx. 4" asphalt pavementDRILLING CONTRACTOR Vine Laboratories
COMPLETED 6/6/25
LOGGED BY AL CHECKED BY AG
HAMMER TYPE Automatic
PROPOSED ELEV.Not Provided
DURING DRILLING None - 6/6/25
AFTER DRILLING Backfilled & patched - 6/6/25
GROUND SURFACE ELEV.Not Provided
SA
M
P
L
E
T
Y
P
E
US
C
S
S
Y
M
B
O
L
GR
A
P
H
I
C
LO
G
DE
P
T
H
(f
t
)
0
5
10
PE
N
E
T
R
A
T
I
O
N
bl
o
w
s
/
i
n
DR
Y
U
N
I
T
W
T
.
(p
c
f
)
SW
E
L
L
-
C
O
N
S
O
L
/S
U
R
C
H
A
R
G
E
LO
A
D
,
%
p
s
f
MO
I
S
T
U
R
E
CO
N
T
E
N
T
(
%
)
RE
C
O
V
E
R
Y
%
MATERIAL DESCRIPTION
PAGE 1 OF 1
BORING NUMBER P4
CLIENT Kentro Group
PROJECT NUMBER 25.22.081
PROJECT NAME Proposed Commercial or Mixed-Use Development
PROJECT LOCATION S. College Ave & W. Drake Rd - Fort Collins, CO
GE
O
T
E
C
H
B
H
C
O
L
U
M
N
S
-
G
I
N
T
S
T
D
U
S
L
A
B
.
G
D
T
-
6
/
3
0
/
2
5
1
3
:
4
9
-
Y
:
\
G
I
N
T
B
A
C
K
U
P
S
\
M
A
I
N
T
R
A
N
S
F
E
R
1
0
.
2
8
\
P
R
O
J
E
C
T
S
G
E
O
2
0
2
5
\
2
5
.
2
2
.
0
8
1
C
O
L
L
E
G
E
A
N
D
D
R
A
K
E
P
R
E
L
I
M
.
G
P
J
Cole Garner Geotechnical1070 W 124th Ave, Suite 300Westminster, CO 80234
APPENDIX B
LABORATORY TEST RESULTS
-10
-8
-6
-4
-2
0
2
4
6
8
10
0.1 1 10 100
CO
N
S
O
L
I
D
A
T
I
O
N
(
-
)
%
S
W
E
L
L
(
+
)
APPLIED PRESSURE, ksf
SWELL/CONSOLIDATION TEST
104 21
Date: 6/9/25Date: 6/9/25Note: Water Added to Sample at 500 psf.
CLIENT Kentro Group
PROJECT NUMBER 25.22.081
PROJECT NAME Proposed Commercial or Mixed-Use Development
PROJECT LOCATION S. College Ave & W. Drake Rd - Fort Collins, CO
BOREHOLE DEPTH
1 4.0 SANDY LEAN CLAY(CL)
Classification MC%
CO
N
S
O
L
S
T
R
A
I
N
S
I
N
G
L
E
-
G
I
N
T
S
T
D
U
S
L
A
B
.
G
D
T
-
6
/
1
9
/
2
5
1
7
:
2
8
-
Y
:
\
G
I
N
T
B
A
C
K
U
P
S
\
M
A
I
N
T
R
A
N
S
F
E
R
1
0
.
2
8
\
P
R
O
J
E
C
T
S
G
E
O
2
0
2
5
\
2
5
.
2
2
.
0
8
1
C
O
L
L
E
G
E
A
N
D
D
R
A
K
E
P
R
E
L
I
M
.
G
P
J
Cole Garner Geotechnical1070 W 124th Ave, Suite 300Westminster, CO 80234
-10
-8
-6
-4
-2
0
2
4
6
8
10
0.1 1 10 100
CO
N
S
O
L
I
D
A
T
I
O
N
(
-
)
%
S
W
E
L
L
(
+
)
APPLIED PRESSURE, ksf
SWELL/CONSOLIDATION TEST
108 19
Date: 6/9/25Date: 6/9/25Note: Water Added to Sample at 500 psf.
CLIENT Kentro Group
PROJECT NUMBER 25.22.081
PROJECT NAME Proposed Commercial or Mixed-Use Development
PROJECT LOCATION S. College Ave & W. Drake Rd - Fort Collins, CO
BOREHOLE DEPTH
1 9.0 SANDY LEAN CLAY
Classification MC%
CO
N
S
O
L
S
T
R
A
I
N
S
I
N
G
L
E
-
G
I
N
T
S
T
D
U
S
L
A
B
.
G
D
T
-
6
/
1
9
/
2
5
1
7
:
2
8
-
Y
:
\
G
I
N
T
B
A
C
K
U
P
S
\
M
A
I
N
T
R
A
N
S
F
E
R
1
0
.
2
8
\
P
R
O
J
E
C
T
S
G
E
O
2
0
2
5
\
2
5
.
2
2
.
0
8
1
C
O
L
L
E
G
E
A
N
D
D
R
A
K
E
P
R
E
L
I
M
.
G
P
J
Cole Garner Geotechnical1070 W 124th Ave, Suite 300Westminster, CO 80234
-10
-8
-6
-4
-2
0
2
4
6
8
10
0.1 1 10 100
CO
N
S
O
L
I
D
A
T
I
O
N
(
-
)
%
S
W
E
L
L
(
+
)
APPLIED PRESSURE, ksf
SWELL/CONSOLIDATION TEST
121 13
Date: 6/9/25Date: 6/9/25Note: Water Added to Sample at 1000 psf.
CLIENT Kentro Group
PROJECT NUMBER 25.22.081
PROJECT NAME Proposed Commercial or Mixed-Use Development
PROJECT LOCATION S. College Ave & W. Drake Rd - Fort Collins, CO
BOREHOLE DEPTH
1 14.0 SANDY LEAN CLAY
Classification MC%
CO
N
S
O
L
S
T
R
A
I
N
S
I
N
G
L
E
-
G
I
N
T
S
T
D
U
S
L
A
B
.
G
D
T
-
6
/
1
9
/
2
5
1
7
:
2
8
-
Y
:
\
G
I
N
T
B
A
C
K
U
P
S
\
M
A
I
N
T
R
A
N
S
F
E
R
1
0
.
2
8
\
P
R
O
J
E
C
T
S
G
E
O
2
0
2
5
\
2
5
.
2
2
.
0
8
1
C
O
L
L
E
G
E
A
N
D
D
R
A
K
E
P
R
E
L
I
M
.
G
P
J
Cole Garner Geotechnical1070 W 124th Ave, Suite 300Westminster, CO 80234
-10
-8
-6
-4
-2
0
2
4
6
8
10
0.1 1 10 100
CO
N
S
O
L
I
D
A
T
I
O
N
(
-
)
%
S
W
E
L
L
(
+
)
APPLIED PRESSURE, ksf
SWELL/CONSOLIDATION TEST
111 16
Date: 6/9/25Date: 6/9/25Note: Water Added to Sample at 500 psf.
CLIENT Kentro Group
PROJECT NUMBER 25.22.081
PROJECT NAME Proposed Commercial or Mixed-Use Development
PROJECT LOCATION S. College Ave & W. Drake Rd - Fort Collins, CO
BOREHOLE DEPTH
2 4.0 SANDY LEAN CLAY
Classification MC%
CO
N
S
O
L
S
T
R
A
I
N
S
I
N
G
L
E
-
G
I
N
T
S
T
D
U
S
L
A
B
.
G
D
T
-
6
/
1
9
/
2
5
1
7
:
2
8
-
Y
:
\
G
I
N
T
B
A
C
K
U
P
S
\
M
A
I
N
T
R
A
N
S
F
E
R
1
0
.
2
8
\
P
R
O
J
E
C
T
S
G
E
O
2
0
2
5
\
2
5
.
2
2
.
0
8
1
C
O
L
L
E
G
E
A
N
D
D
R
A
K
E
P
R
E
L
I
M
.
G
P
J
Cole Garner Geotechnical1070 W 124th Ave, Suite 300Westminster, CO 80234
-10
-8
-6
-4
-2
0
2
4
6
8
10
0.1 1 10 100
CO
N
S
O
L
I
D
A
T
I
O
N
(
-
)
%
S
W
E
L
L
(
+
)
APPLIED PRESSURE, ksf
SWELL/CONSOLIDATION TEST
112 18
Date: 6/9/25Date: 6/9/25Note: Water Added to Sample at 1000 psf.
CLIENT Kentro Group
PROJECT NUMBER 25.22.081
PROJECT NAME Proposed Commercial or Mixed-Use Development
PROJECT LOCATION S. College Ave & W. Drake Rd - Fort Collins, CO
BOREHOLE DEPTH
2 14.0 SANDY LEAN CLAY
Classification MC%
CO
N
S
O
L
S
T
R
A
I
N
S
I
N
G
L
E
-
G
I
N
T
S
T
D
U
S
L
A
B
.
G
D
T
-
6
/
1
9
/
2
5
1
7
:
2
8
-
Y
:
\
G
I
N
T
B
A
C
K
U
P
S
\
M
A
I
N
T
R
A
N
S
F
E
R
1
0
.
2
8
\
P
R
O
J
E
C
T
S
G
E
O
2
0
2
5
\
2
5
.
2
2
.
0
8
1
C
O
L
L
E
G
E
A
N
D
D
R
A
K
E
P
R
E
L
I
M
.
G
P
J
Cole Garner Geotechnical1070 W 124th Ave, Suite 300Westminster, CO 80234
-10
-8
-6
-4
-2
0
2
4
6
8
10
0.1 1 10 100
CO
N
S
O
L
I
D
A
T
I
O
N
(
-
)
%
S
W
E
L
L
(
+
)
APPLIED PRESSURE, ksf
SWELL/CONSOLIDATION TEST
102 23
Date: 6/9/25Date: 6/9/25Note: Water Added to Sample at 500 psf.
CLIENT Kentro Group
PROJECT NUMBER 25.22.081
PROJECT NAME Proposed Commercial or Mixed-Use Development
PROJECT LOCATION S. College Ave & W. Drake Rd - Fort Collins, CO
BOREHOLE DEPTH
3 4.0 SANDY LEAN CLAY
Classification MC%
CO
N
S
O
L
S
T
R
A
I
N
S
I
N
G
L
E
-
G
I
N
T
S
T
D
U
S
L
A
B
.
G
D
T
-
6
/
1
9
/
2
5
1
7
:
2
8
-
Y
:
\
G
I
N
T
B
A
C
K
U
P
S
\
M
A
I
N
T
R
A
N
S
F
E
R
1
0
.
2
8
\
P
R
O
J
E
C
T
S
G
E
O
2
0
2
5
\
2
5
.
2
2
.
0
8
1
C
O
L
L
E
G
E
A
N
D
D
R
A
K
E
P
R
E
L
I
M
.
G
P
J
Cole Garner Geotechnical1070 W 124th Ave, Suite 300Westminster, CO 80234
-10
-8
-6
-4
-2
0
2
4
6
8
10
0.1 1 10 100
CO
N
S
O
L
I
D
A
T
I
O
N
(
-
)
%
S
W
E
L
L
(
+
)
APPLIED PRESSURE, ksf
SWELL/CONSOLIDATION TEST
130 10
Date: 6/9/25Date: 6/9/25Note: Water Added to Sample at 500 psf.
CLIENT Kentro Group
PROJECT NUMBER 25.22.081
PROJECT NAME Proposed Commercial or Mixed-Use Development
PROJECT LOCATION S. College Ave & W. Drake Rd - Fort Collins, CO
BOREHOLE DEPTH
3 9.0 SANDY LEAN CLAY
Classification MC%
CO
N
S
O
L
S
T
R
A
I
N
S
I
N
G
L
E
-
G
I
N
T
S
T
D
U
S
L
A
B
.
G
D
T
-
6
/
1
9
/
2
5
1
7
:
2
8
-
Y
:
\
G
I
N
T
B
A
C
K
U
P
S
\
M
A
I
N
T
R
A
N
S
F
E
R
1
0
.
2
8
\
P
R
O
J
E
C
T
S
G
E
O
2
0
2
5
\
2
5
.
2
2
.
0
8
1
C
O
L
L
E
G
E
A
N
D
D
R
A
K
E
P
R
E
L
I
M
.
G
P
J
Cole Garner Geotechnical1070 W 124th Ave, Suite 300Westminster, CO 80234
-10
-8
-6
-4
-2
0
2
4
6
8
10
0.1 1 10 100
CO
N
S
O
L
I
D
A
T
I
O
N
(
-
)
%
S
W
E
L
L
(
+
)
APPLIED PRESSURE, ksf
SWELL/CONSOLIDATION TEST
97 25
Date: 6/9/25Date: 6/9/25Note: Water Added to Sample at 500 psf.
CLIENT Kentro Group
PROJECT NUMBER 25.22.081
PROJECT NAME Proposed Commercial or Mixed-Use Development
PROJECT LOCATION S. College Ave & W. Drake Rd - Fort Collins, CO
BOREHOLE DEPTH
4 4.0 LEAN CLAY with SAND(CL)
Classification MC%
CO
N
S
O
L
S
T
R
A
I
N
S
I
N
G
L
E
-
G
I
N
T
S
T
D
U
S
L
A
B
.
G
D
T
-
6
/
1
9
/
2
5
1
7
:
2
8
-
Y
:
\
G
I
N
T
B
A
C
K
U
P
S
\
M
A
I
N
T
R
A
N
S
F
E
R
1
0
.
2
8
\
P
R
O
J
E
C
T
S
G
E
O
2
0
2
5
\
2
5
.
2
2
.
0
8
1
C
O
L
L
E
G
E
A
N
D
D
R
A
K
E
P
R
E
L
I
M
.
G
P
J
Cole Garner Geotechnical1070 W 124th Ave, Suite 300Westminster, CO 80234
-10
-8
-6
-4
-2
0
2
4
6
8
10
0.1 1 10 100
CO
N
S
O
L
I
D
A
T
I
O
N
(
-
)
%
S
W
E
L
L
(
+
)
APPLIED PRESSURE, ksf
SWELL/CONSOLIDATION TEST
113 18
Date: 6/9/25Date: 6/9/25Note: Water Added to Sample at 1000 psf.
CLIENT Kentro Group
PROJECT NUMBER 25.22.081
PROJECT NAME Proposed Commercial or Mixed-Use Development
PROJECT LOCATION S. College Ave & W. Drake Rd - Fort Collins, CO
BOREHOLE DEPTH
4 14.0 SANDY LEAN CLAY
Classification MC%
CO
N
S
O
L
S
T
R
A
I
N
S
I
N
G
L
E
-
G
I
N
T
S
T
D
U
S
L
A
B
.
G
D
T
-
6
/
1
9
/
2
5
1
7
:
2
8
-
Y
:
\
G
I
N
T
B
A
C
K
U
P
S
\
M
A
I
N
T
R
A
N
S
F
E
R
1
0
.
2
8
\
P
R
O
J
E
C
T
S
G
E
O
2
0
2
5
\
2
5
.
2
2
.
0
8
1
C
O
L
L
E
G
E
A
N
D
D
R
A
K
E
P
R
E
L
I
M
.
G
P
J
Cole Garner Geotechnical1070 W 124th Ave, Suite 300Westminster, CO 80234
-10
-8
-6
-4
-2
0
2
4
6
8
10
0.1 1 10 100
CO
N
S
O
L
I
D
A
T
I
O
N
(
-
)
%
S
W
E
L
L
(
+
)
APPLIED PRESSURE, ksf
SWELL/CONSOLIDATION TEST
112 16
Date: 6/9/25Date: 6/9/25Note: Water Added to Sample at 500 psf.
CLIENT Kentro Group
PROJECT NUMBER 25.22.081
PROJECT NAME Proposed Commercial or Mixed-Use Development
PROJECT LOCATION S. College Ave & W. Drake Rd - Fort Collins, CO
BOREHOLE DEPTH
P1 4.0 FILL - SANDY LEAN CLAY
Classification MC%
CO
N
S
O
L
S
T
R
A
I
N
S
I
N
G
L
E
-
G
I
N
T
S
T
D
U
S
L
A
B
.
G
D
T
-
6
/
1
9
/
2
5
1
7
:
2
8
-
Y
:
\
G
I
N
T
B
A
C
K
U
P
S
\
M
A
I
N
T
R
A
N
S
F
E
R
1
0
.
2
8
\
P
R
O
J
E
C
T
S
G
E
O
2
0
2
5
\
2
5
.
2
2
.
0
8
1
C
O
L
L
E
G
E
A
N
D
D
R
A
K
E
P
R
E
L
I
M
.
G
P
J
Cole Garner Geotechnical1070 W 124th Ave, Suite 300Westminster, CO 80234
-10
-8
-6
-4
-2
0
2
4
6
8
10
0.1 1 10 100
CO
N
S
O
L
I
D
A
T
I
O
N
(
-
)
%
S
W
E
L
L
(
+
)
APPLIED PRESSURE, ksf
SWELL/CONSOLIDATION TEST
106 17
Date: 6/9/25Date: 6/9/25Note: Water Added to Sample at 200 psf.
CLIENT Kentro Group
PROJECT NUMBER 25.22.081
PROJECT NAME Proposed Commercial or Mixed-Use Development
PROJECT LOCATION S. College Ave & W. Drake Rd - Fort Collins, CO
BOREHOLE DEPTH
P2 2.0 LEAN CLAY(CL)
Classification MC%
CO
N
S
O
L
S
T
R
A
I
N
S
I
N
G
L
E
-
G
I
N
T
S
T
D
U
S
L
A
B
.
G
D
T
-
6
/
1
9
/
2
5
1
7
:
2
8
-
Y
:
\
G
I
N
T
B
A
C
K
U
P
S
\
M
A
I
N
T
R
A
N
S
F
E
R
1
0
.
2
8
\
P
R
O
J
E
C
T
S
G
E
O
2
0
2
5
\
2
5
.
2
2
.
0
8
1
C
O
L
L
E
G
E
A
N
D
D
R
A
K
E
P
R
E
L
I
M
.
G
P
J
Cole Garner Geotechnical1070 W 124th Ave, Suite 300Westminster, CO 80234
-10
-8
-6
-4
-2
0
2
4
6
8
10
0.1 1 10 100
CO
N
S
O
L
I
D
A
T
I
O
N
(
-
)
%
S
W
E
L
L
(
+
)
APPLIED PRESSURE, ksf
SWELL/CONSOLIDATION TEST
98 23
Date: 6/9/25Date: 6/9/25Note: Water Added to Sample at 200 psf.
CLIENT Kentro Group
PROJECT NUMBER 25.22.081
PROJECT NAME Proposed Commercial or Mixed-Use Development
PROJECT LOCATION S. College Ave & W. Drake Rd - Fort Collins, CO
BOREHOLE DEPTH
P3 2.0 LEAN CLAY with SAND(CL)
Classification MC%
CO
N
S
O
L
S
T
R
A
I
N
S
I
N
G
L
E
-
G
I
N
T
S
T
D
U
S
L
A
B
.
G
D
T
-
6
/
1
9
/
2
5
1
7
:
2
8
-
Y
:
\
G
I
N
T
B
A
C
K
U
P
S
\
M
A
I
N
T
R
A
N
S
F
E
R
1
0
.
2
8
\
P
R
O
J
E
C
T
S
G
E
O
2
0
2
5
\
2
5
.
2
2
.
0
8
1
C
O
L
L
E
G
E
A
N
D
D
R
A
K
E
P
R
E
L
I
M
.
G
P
J
Cole Garner Geotechnical1070 W 124th Ave, Suite 300Westminster, CO 80234
-10
-8
-6
-4
-2
0
2
4
6
8
10
0.1 1 10 100
CO
N
S
O
L
I
D
A
T
I
O
N
(
-
)
%
S
W
E
L
L
(
+
)
APPLIED PRESSURE, ksf
SWELL/CONSOLIDATION TEST
104 22
Date: 6/9/25Date: 6/9/25Note: Water Added to Sample at 200 psf.
CLIENT Kentro Group
PROJECT NUMBER 25.22.081
PROJECT NAME Proposed Commercial or Mixed-Use Development
PROJECT LOCATION S. College Ave & W. Drake Rd - Fort Collins, CO
BOREHOLE DEPTH
P4 2.0 SANDY LEAN CLAY
Classification MC%
CO
N
S
O
L
S
T
R
A
I
N
S
I
N
G
L
E
-
G
I
N
T
S
T
D
U
S
L
A
B
.
G
D
T
-
6
/
1
9
/
2
5
1
7
:
2
8
-
Y
:
\
G
I
N
T
B
A
C
K
U
P
S
\
M
A
I
N
T
R
A
N
S
F
E
R
1
0
.
2
8
\
P
R
O
J
E
C
T
S
G
E
O
2
0
2
5
\
2
5
.
2
2
.
0
8
1
C
O
L
L
E
G
E
A
N
D
D
R
A
K
E
P
R
E
L
I
M
.
G
P
J
Cole Garner Geotechnical1070 W 124th Ave, Suite 300Westminster, CO 80234
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
0.0010.010.1110100
PI Cc
1721
CuLL PL
4
GRAIN SIZE DISTRIBUTION
COBBLES GRAVEL
25.8
SAND
GRAIN SIZE IN MILLIMETERS
coarse fine
Classification
D100 D60 D30 D10 %Gravel
0.438
2
coarse SILT OR CLAYfinemedium
9.0
%Sand %Silt %Clay
0.099 0.1 74.1
BOREHOLE DEPTH
BOREHOLE DEPTH
3 100
2
24 16 30
1 2006 10 501/2
HYDROMETERU.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS
1403420 406 601.5 8 143/4 3/8
9.0
PE
R
C
E
N
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9.5
CLIENT Kentro Group
PROJECT NUMBER 25.22.081
PROJECT NAME Proposed Commercial or Mixed-Use Development
PROJECT LOCATION S. College Ave & W. Drake Rd - Fort Collins, CO
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Cole Garner Geotechnical1070 W 124th Ave, Suite 300Westminster, CO 80234
1 4 SANDY LEAN CLAY(CL)20.6 104.4 +0.4/500 0 54 28 15 13
1 9 SANDY LEAN CLAY 18.8 107.8 +0.2/500
1 14 SANDY LEAN CLAY 13.3 120.5 +0.3/1000
1 24 SANDY LEAN CLAY 20.5 106.8
2 4 SANDY LEAN CLAY 16.4 110.7 -0.3/500
2 9 SILTY, CLAYEY SAND(SC-SM) 9.1 132.0 26 21 17 4
2 14 SANDY LEAN CLAY 17.7 112.4 -0.5/1000
2 19 SANDY LEAN CLAY 17.5 119.7
2 24 SANDY LEAN CLAY 18.3 115.8
2 29 CLAYEY to SILTY SAND 13.7 126.7
2 34 SANDSTONE BEDROCK 18.5
3 4 SANDY LEAN CLAY 23.5 102.4 +0.6/500
3 9 SANDY LEAN CLAY 10.2 130.3 -0.4/500
3 14 SANDY LEAN CLAY 16.9 116.6
3 19 SANDY LEAN CLAY 18.0 122.8
3 24 SANDY LEAN CLAY 19.6 114.9
3 39 SANDSTONE BEDROCK 15.9 118.9
4 4 LEAN CLAY with SAND(CL) 24.6 96.9 -1.0/500 0 80 42 19 23
4 9 SANDY LEAN CLAY to CLAYEY SAND 11.1
4 14 SANDY LEAN CLAY 18.2 112.9 -3.5/1000
4 19 SANDY LEAN CLAY 18.0 120.1
4 24 SANDY LEAN CLAY 16.7 121.9
4 34 SANDSTONE BEDROCK 16.5
P1 2 FILL - SANDY LEAN CLAY to CLAYEY SAND 11.9
P1 4 FILL - SANDY LEAN CLAY 16.2 111.7 -0.4/500 69 38 17 21
P1 9 SANDY LEAN CLAY to CLAYEY SAND 11.7 133.9
P2 2 LEAN CLAY(CL)17.4 105.5 +0.3/200 0 89 40 18 22
P2 4 LEAN CLAY with SAND 24.7 97.1
P2 9 CLAYEY SAND 8.4 137.6
P3 2 LEAN CLAY with SAND(CL) 22.9 97.5 +0.5/200 83 39 19 20
Water
Content
(%)
PAGE 1 OF 2
Liquid
Limit
Atterberg LimitsDry
Density
(pcf)
Passing
#200 Sieve
(%)
Water Soluble
Sulfates
(ppm)
SUMMARY OF LABORATORY RESULTS
Soil Description Plastic
Limit
Plasticity
Index
Borehole Depth
Swell (+) or
Consolidation (-)/
Surcharge
(%/psf)
CLIENT Kentro Group
PROJECT NUMBER 25.22.081
PROJECT NAME Proposed Commercial or Mixed-Use Development
PROJECT LOCATION S. College Ave & W. Drake Rd - Fort Collins, CO
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Cole Garner Geotechnical1070 W 124th Ave, Suite 300Westminster, CO 80234
P3 4 LEAN CLAY with SAND 17.1
P3 9 CLAYEY SAND 10.3 131.1
P4 2 SANDY LEAN CLAY 21.8 103.6 +0.6/200
P4 4 SANDY LEAN CLAY to CLAYEY SAND 16.0 123.1
P4 9 SANDY LEAN CLAY 15.2 118.7
Water
Content
(%)
PAGE 2 OF 2
Liquid
Limit
Atterberg LimitsDry
Density
(pcf)
Passing
#200 Sieve
(%)
Water Soluble
Sulfates
(ppm)
SUMMARY OF LABORATORY RESULTS
Soil Description Plastic
Limit
Plasticity
Index
Borehole Depth
Swell (+) or
Consolidation (-)/
Surcharge
(%/psf)
CLIENT Kentro Group
PROJECT NUMBER 25.22.081
PROJECT NAME Proposed Commercial or Mixed-Use Development
PROJECT LOCATION S. College Ave & W. Drake Rd - Fort Collins, CO
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Cole Garner Geotechnical1070 W 124th Ave, Suite 300Westminster, CO 80234
APPENDIX C
GENERAL NOTES
GENERAL NOTES
DRILLING & SAMPLING SYMBOLS:
SS: Split Spoon - 1!" I.D., 2" O.D., unless otherwise noted HS: Hollow Stem Auger
ST: Thin-Walled Tube – 2.5" O.D., unless otherwise noted PA: Power Auger
RS: Ring Sampler - 2.42" I.D., 3" O.D., unless otherwise noted HA: Hand Auger
CB: California Barrel - 1.92" I.D., 2.5" O.D., unless otherwise noted RB: Rock Bit
BS: Bulk Sample or Auger Sample WB: Wash Boring or Mud Rotary
The number of blows required to advance a standard 2-inch O.D. split-spoon sampler (SS) the last 12 inches of the total 18-inch
penetration with a 140-pound hammer falling 30 inches is considered the “Standard Penetration” or “N-value”. For 2.5” O.D.
California Barrel samplers (CB) the penetration value is reported as the number of blows required to advance the sampler 12
inches using a 140-pound hammer falling 30 inches, reported as “blows per inch,” and is not considered equivalent to the
“Standard Penetration” or “N-value”.
WATER LEVEL MEASUREMENT SYMBOLS:
WL: Water Level WS: While Sampling
WCI: Wet Cave in WD: While Drilling
DCI: Dry Cave in BCR: Before Casing Removal
AB: After Boring ACR: After Casing Removal
Water levels indicated on the boring logs are the levels measured in the borings at the times indicated. Groundwater levels at other
times and other locations across the site could vary. In pervious soils, the indicated levels may reflect the location of groundwater.
In low permeability soils, the accurate determination of groundwater levels may not be possible with only short-term observations.
DESCRIPTIVE SOIL CLASSIFICATION: Soil classification is based on the Unified Classification System. Coarse Grained Soils
have more than 50% of their dry weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand.
Fine Grained Soils have less than 50% of their dry weight retained on a #200 sieve; they are principally described as clays if they
are plastic, and silts if they are slightly plastic or non-plastic. Major constituents may be added as modifiers and minor constituents
may be added according to the relative proportions based on grain size. In addition to gradation, coarse-grained soils are defined
on the basis of their in-place relative density and fine-grained soils on the basis of their consistency.
FINE-GRAINED SOILS COARSE-GRAINED SOILS BEDROCK
(CB)
Blows/Ft.
(SS)
Blows/Ft.
Consistency
(CB)
Blows/Ft.
(SS)
Blows/Ft.
Relative
Density
(CB)
Blows/Ft.
(SS)
Blows/Ft.
Consistency
< 3 0-2 Very Soft 0-5 < 3 Very Loose < 24 < 20 Weathered
3-5 3-4 Soft 6-14 4-9 Loose 24-35 20-29 Firm
6-10 5-8 Medium Stiff 15-46 10-29 Medium Dense 36-60 30-49 Medium Hard
11-18 9-15 Stiff 47-79 30-50 Dense 61-96 50-79 Hard
19-36 16-30 Very Stiff > 79 > 50 Very Dense > 96 > 79 Very Hard
> 36 > 30 Hard
RELATIVE PROPORTIONS OF SAND AND
GRAVEL
GRAIN SIZE TERMINOLOGY
Descriptive Terms of
Other Constituents
Percent of
Dry Weight
Major Component
of Sample
Particle Size
Trace < 15 Boulders Over 12 in. (300mm)
With 15 – 29 Cobbles 12 in. to 3 in. (300mm to 75 mm)
Modifier > 30 Gravel 3 in. to #4 sieve (75mm to 4.75 mm)
Sand
Silt or Clay
#4 to #200 sieve (4.75mm to 0.075mm)
Passing #200 Sieve (0.075mm)
RELATIVE PROPORTIONS OF FINES PLASTICITY DESCRIPTION
Descriptive Terms of
Other Constituents
Percent of
Dry Weight
Term Plasticity Index
Trace
With
Modifiers
< 5
5 – 12
> 12
Non-plastic
Low
Medium
High
0
1-10
11-30
30+
UNIFIED SOIL CLASSIFICATION SYSTEM
Criteria for Assigning Group Symbols and Group Names Using Laboratory TestsA Soil Classification
Group
Symbol
Group NameB
Cu ! 4 and 1 " Cc " 3E GW Well graded gravelF Clean Gravels
Less than 5% finesC Cu < 4 and/or 1 > Cc > 3E GP Poorly graded gravelF
Fines classify as ML or MH GM Silty gravelF,G, H
Coarse Grained Soils
More than 50% retained
on No. 200 sieve
Gravels
More than 50% of coarse
fraction retained on
No. 4 sieve Gravels with Fines More
than 12% finesC Fines classify as CL or CH GC Clayey gravelF,G,H
Cu ! 6 and 1 " Cc " 3E SW Well graded sandI Clean Sands
Less than 5% finesD Cu < 6 and/or 1 > Cc > 3E SP Poorly graded sandI
Fines classify as ML or MH SM Silty sandG,H,I
Sands
50% or more of coarse
fraction passes
No. 4 sieve Sands with Fines
More than 12% finesD Fines classify as CL or CH SC Clayey sandG,H,I
PI > 7 and plots on or above “A” lineJ CL Lean clayK,L,M Silts and Clays
Liquid limit less than 50
Inorganic
PI < 4 or plots below “A” lineJ ML SiltK,L,M
Liquid limit - oven
dried
Organic clayK,L,M,N
Fine-Grained Soils
50% or more passes the
No. 200 sieve
Organic
Liquid limit - not
dried
< 0.75 OL
Organic siltK,L,M,O
Inorganic PI plots on or above “A” line CH Fat clayK,L,M
Silts and Clays
Liquid limit 50 or more PI plots below “A” line MH Elastic siltK,L,M
Liquid limit - oven dried Organic clayK,L,M,P Organic
Liquid limit - not dried
< 0.75 OH
Organic siltK,L,M,Q
Highly organic soils Primarily organic matter, dark in color, and organic odor PT Peat
A Based on the material passing the 3-in. (75-mm) sieve
B If field sample contained cobbles or boulders, or both, add “with cobbles
or boulders, or both” to group name.
C Gravels with 5 to 12% fines require dual symbols: GW-GM well graded
gravel with silt, GW-GC well graded gravel with clay, GP-GM poorly
graded gravel with silt, GP-GC poorly graded gravel with clay.
D Sands with 5 to 12% fines require dual symbols: SW-SM well graded
sand with silt, SW-SC well graded sand with clay, SP-SM poorly graded
sand with silt, SP-SC poorly graded sand with clay
E Cu = D60/D10 Cc =
F If soil contains ! 15% sand, add “with sand” to group name.
G If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM.
HIf fines are organic, add “with organic fines” to group name.
I If soil contains ! 15% gravel, add “with gravel” to group name.
J If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay.
K If soil contains 15 to 29% plus No. 200, add “with sand” or “with
gravel,” whichever is predominant.
L If soil contains ! 30% plus No. 200 predominantly sand, add
“sandy” to group name.
M If soil contains ! 30% plus No. 200, predominantly gravel, add
“gravelly” to group name.
N PI ! 4 and plots on or above “A” line.
O PI < 4 or plots below “A” line.
P PI plots on or above “A” line.
Q PI plots below “A” line.
ROCK CLASSIFICATION
(Based on ASTM C-294)
Sedimentary Rocks
Sedimentary rocks are stratified materials laid down by water or wind. The sediments may be
composed of particles or pre-existing rocks derived by mechanical weathering, evaporation or by
chemical or organic origin. The sediments are usually indurated by cementation or compaction.
Chert Very fine-grained siliceous rock composed of micro-crystalline or cyrptocrystalline
quartz, chalcedony or opal. Chert is various colored, porous to dense, hard and
has a conchoidal to splintery fracture.
Claystone Fine-grained rock composed of or derived by erosion of silts and clays or any rock
containing clay. Soft massive and may contain carbonate minerals.
Conglomerate Rock consisting of a considerable amount of rounded gravel, sand and cobbles
with or without interstitial or cementing material. The cementing or interstitial
material may be quartz, opal, calcite, dolomite, clay, iron oxides or other
materials.
Dolomite A fine-grained carbonate rock consisting of the mineral dolomite [CaMg(CO3)2].
May contain noncarbonate impurities such as quartz, chert, clay minerals, organic
matter, gypsum and sulfides. Reacts with hydrochloric acid (HCL).
Limestone A fine-grained carbonate rock consisting of the mineral calcite (CaCO3). May
contain noncarbonate impurities such as quartz, chert, clay minerals, organic
matter, gypsum and sulfides. Reacts with hydrochloric acid (HCL).
Sandstone Rock consisting of particles of sand with or without interstitial and cementing
materials. The cementing or interstitial material may be quartz, opal, calcite,
dolomite, clay, iron oxides or other material.
Shale Fine-grained rock composed of or derived by erosion of silts and clays or any rock
containing clay. Shale is hard, platy, of fissile may be gray, black, reddish or
green and may contain some carbonate minerals (calcareous shale).
Siltstone Fine grained rock composed of or derived by erosion of silts or rock containing
silt. Siltstones consist predominantly of silt sized particles (0.0625 to 0.002 mm in
diameter) and are intermediate rocks between claystones and sandstones and
may contain carbonate minerals.
LABORATORY TEST
SIGNIFICANCE AND PURPOSE
TEST SIGNIFICANCE PURPOSE
California Bearing
Ratio
Used to evaluate the potential strength of subgrade soil,
subbase, and base course material, including recycled
materials for use in road and airfield pavements.
Pavement Thickness
Design
Consolidation Used to develop an estimate of both the rate and amount of
both differential and total settlement of a structure.
Foundation Design
Direct Shear Used to determine the consolidated drained shear strength
of soil or rock.
Bearing Capacity,
Foundation Design,
and Slope Stability
Dry Density Used to determine the in-place density of natural, inorganic,
fine-grained soils.
Index Property Soil
Behavior
Expansion Used to measure the expansive potential of fine-grained
soil and to provide a basis for swell potential classification.
Foundation and Slab
Design
Gradation Used for the quantitative determination of the distribution of
particle sizes in soil.
Soil Classification
Liquid & Plastic Limit,
Plasticity Index
Used as an integral part of engineering classification
systems to characterize the fine-grained fraction of soils,
and to specify the fine-grained fraction of construction
materials.
Soil Classification
Permeability Used to determine the capacity of soil or rock to conduct a
liquid or gas.
Groundwater Flow
Analysis
pH Used to determine the degree of acidity or alkalinity of a
soil.
Corrosion Potential
Resistivity Used to indicate the relative ability of a soil medium to carry
electrical currents.
Corrosion Potential
R-Value Used to evaluate the potential strength of subgrade soil,
subbase, and base course material, including recycled
materials for use in road and airfield pavements.
Pavement Thickness
Design
Soluble Sulfate Used to determine the quantitative amount of soluble
sulfates within a soil mass.
Corrosion Potential
Unconfined
Compression
To obtain the approximate compressive strength of soils
that possess sufficient cohesion to permit testing in the
unconfined state.
Bearing Capacity
Analysis for
Foundations
Water Content Used to determine the quantitative amount of water in a soil
mass.
Index Property Soil
Behavior
REPORT TERMINOLOGY
(Based on ASTM D653)
Allowable Soil
Bearing Capacity
The recommended maximum contact stress developed at the interface of the foundation
element and the supporting material.
Alluvium Soil, the constituents of which have been transported in suspension by flowing water and
subsequently deposited by sedimentation.
Aggregate Base
Course
A layer of specified material placed on a subgrade or subbase usually beneath slabs or
pavements.
Backfill A specified material placed and compacted in a confined area.
Bedrock A natural aggregate of mineral grains connected by strong and permanent cohesive forces.
Usually requires drilling, wedging, blasting or other methods of extraordinary force for
excavation.
Bench A horizontal surface in a sloped deposit.
Caisson (Drilled
Pier or Shaft)
A concrete foundation element cast in a circular excavation which may have an enlarged
base. Sometimes referred to as a cast-in-place pier or drilled shaft.
Coefficient of
Friction
A constant proportionality factor relating normal stress and the corresponding shear stress
at which sliding starts between the two surfaces.
Colluvium Soil, the constituents of which have been deposited chiefly by gravity such as at the foot of a
slope or cliff.
Compaction The densification of a soil by means of mechanical manipulation
Concrete Slab-on-
Grade
A concrete surface layer cast directly upon a base, subbase or subgrade, and typically used
as a floor system.
Differential
Movement
Unequal settlement or heave between, or within foundation elements of structure.
Earth Pressure The pressure exerted by soil on any boundary such as a foundation wall.
ESAL Equivalent Single Axle Load, a criteria used to convert traffic to a uniform standard, (18,000
pound axle loads).
Engineered Fill Specified material placed and compacted to specified density and/or moisture conditions
under observations of a representative of a geotechnical engineer.
Equivalent Fluid A hypothetical fluid having a unit weight such that it will produce a pressure against a lateral
support presumed to be equivalent to that produced by the actual soil. This simplified
approach is valid only when deformation conditions are such that the pressure increases
linearly with depth and the wall friction is neglected.
Existing Fill (or
Man-Made Fill)
Materials deposited throughout the action of man prior to exploration of the site.
Existing Grade The ground surface at the time of field exploration.
REPORT TERMINOLOGY
(Based on ASTM D653)
Expansive
Potential
The potential of a soil to expand (increase in volume) due to absorption of moisture.
Finished Grade The final grade created as a part of the project.
Footing A portion of the foundation of a structure that transmits loads directly to the soil.
Foundation The lower part of a structure that transmits the loads to the soil or bedrock.
Frost Depth The depth at which the ground becomes frozen during the winter season.
Grade Beam A foundation element or wall, typically constructed of reinforced concrete, used to span
between other foundation elements such as drilled piers.
Groundwater Subsurface water found in the zone of saturation of soils or within fractures in bedrock.
Heave Upward movement.
Lithologic The characteristics which describe the composition and texture of soil and rock by
observation.
Native Grade The naturally occurring ground surface.
Native Soil Naturally occurring on-site soil, sometimes referred to as natural soil.
Optimum Moisture
Content
The water content at which a soil can be compacted to a maximum dry unit weight by a
given compactive effort.
Perched Water Groundwater, usually of limited area maintained above a normal water elevation by the
presence of an intervening relatively impervious continuous stratum.
Scarify To mechanically loosen soil or break down existing soil structure.
Settlement Downward movement.
Skin Friction (Side
Shear)
The frictional resistance developed between soil and an element of the structure such as a
drilled pier.
Soil (Earth) Sediments or other unconsolidated accumulations of solid particles produced by the
physical and chemical disintegration of rocks, and which may or may not contain organic
matter.
Strain The change in length per unit of length in a given direction.
Stress The force per unit area acting within a soil mass.
Strip To remove from present location.
Subbase A layer of specified material in a pavement system between the subgrade and base course.
Subgrade The soil prepared and compacted to support a structure, slab or pavement system.