HomeMy WebLinkAboutFORT COLLINS NISSAN-KIA - FDP220011 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORT
REPORT COVER PAGE
Geotechnical Engineering Report
__________________________________________________________________________
Fort Collins Nissan and Kia Dealerships
Fort Collins, Colorado
April 7, 2021
Terracon Project No. 20215013
Prepared for:
TCC Corporation
Windsor, Colorado
Prepared by:
Terracon Consultants, Inc.
Fort Collins, Colorado
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REPORT TOPICS
INTRODUCTION ............................................................................................................. 1
SITE CONDITIONS ......................................................................................................... 1
PROJECT DESCRIPTION .............................................................................................. 2
GEOTECHNICAL CHARACT ERIZATION ...................................................................... 3
GEOTECHNICAL OVERVIEW ....................................................................................... 5
EARTHWORK................................................................................................................. 6
SHALLOW FOUNDATIONS ......................................................................................... 13
SEISMIC CONSIDERATIONS ...................................................................................... 14
FLOOR SLABS............................................................................................................. 15
PAVEMENTS ................................................................................................................ 16
CORROSIVITY.............................................................................................................. 19
GENERAL COMMENTS ............................................................................................... 19
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ATTACHMENTS
EXPLORATION AND TESTING PROCEDURES
SITE LOCATION AND EXPLORATION PLANS
EXPLORATION RESULTS
SUPPORTING INFORMATION
Note: Refer to each individual Attachment for a listing of contents.
Geotechnical Engineering Report
Fort Collins Nissan and Kia Dealerships ■ Fort Collins, Colorado
April 7, 2021 ■ Terracon Project No. 20215013
Responsive ■ Resourceful ■ Reliable i
REPORT SUMMARY
Topic 1 Overview Statement 2
Project
Overview
A geotechnical exploration has been performed for the proposed Fort Collins Nissan
and Kia Dealerships to be constructed west of the intersection of South College
Avenue and Crestridge Drive in Fort Collins, Colorado. Eight (8) borings were
performed to depths of approximately 15 to 30 feet below existing site grades.
Subsurface
Conditions
Subsurface conditions encountered in our exploratory borings generally consisted of
about 1 to 2 feet of lean clay with varying amounts of sand over sandstone bedrock.
Sandstone bedrock was generally hard to very hard with cemented lenses. Boring logs
are presented in the Exploration Results section of this report.
Groundwater
Conditions
Groundwater was encountered in one of our test borings at a depth of about 14 feet
below existing site grades at the time of drilling. Groundwater was not encountered
during drilling in any of our other test borings. Groundwater levels can fluctuate in
response to site development and to varying seasonal and weather conditions,
irrigation on or adjacent to the site and fluctuations in nearby water features. However,
we do not believe groundwater will significantly impact the proposed construction.
Geotechnical
Concerns
■ As previously stated, bedrock was encountered at depths ranging from about 1 to 3
feet below existing site grades. Bedrock was generally hard to very hard with
cemented lenses throughout. Excavation penetrating the bedrock may require the
use of specialized heavy-duty equipment, together with ripping or jack-hammering
to advance the excavation and facilitate rock break-up and removal. Consideration
should be given to obtaining a unit price for difficult excavation in the contract
documents for the project.
■ A sample of on-site soils exhibited 2.3 percent swell upon wetting. Expansive soils
are anticipated to be encountered in the clay soils in the upper approximately 1 to 3
feet below existing site grades above the sandstone bedrock, these conditions
constitute a geologic hazard. This report provides recommendations to help mitigate
the effects of soil shrinkage and expansion. However, even if these procedures are
followed, some movement and cracking in the structures, pavements, and flatwork
is possible. The severity of cracking and other damage such as uneven floor slabs
and flat work will probably increase if modification of the site results in excessive
wetting or drying of the expansive clays. Eliminating the risk of movement and
cosmetic distress is generally not feasible, but it may be possible to further reduce
the risk of movement if significantly more expensive measures are used during
construction. It is imperative the recommendations described in section Grading
and Drainage section of the Earthwork section of this report be followed to reduce
potential movement. Clay soils used as backfill or fill on the site should be probably
moisture conditioned prior to placement to help mitigate the effects of soil shrinkage
and expansion.
■ An existing Nissan dealership and associated parking and drive areas currently
occupy the south side of the site. Although not encountered in our exploratory
borings, based on the existing structures we anticipate existing undocumented fill
could be encountered at the site, particularly under the existing building and
associated structures. If fill is encountered, we do not possess any information
regarding whether the fill was placed under the observation of a geotechnical
engineer. Undocumented fill can present a greater than normal risk of post-
construction movement of foundations, slabs, pavements and other site
improvements supported on or above these materials. Consequently, it is our
opinion existing fill on the site (if any) should not be relied upon for support and
Geotechnical Engineering Report
Fort Collins Nissan and Kia Dealerships ■ Fort Collins, Colorado
April 7, 2021 ■ Terracon Project No. 20215013
Responsive ■ Resourceful ■ Reliable ii
Topic 1 Overview Statement 2
should be removed down to native soil, moisture conditioned and recompacted prior
to new fill placement and/or construction.
Earthwork
On-site soils typically appear suitable for use as general engineered fill and backfill on
the site provided they are placed and compacted as described in this report. Import
materials (if needed) should be evaluated and approved by Terracon prior to delivery
to the site. Earthwork recommendations are presented in the Earthwork section of
this report.
Grading and
Drainage
The amount of movement of foundations, floor slabs, pavements, etc. will be related to
the wetting of underlying supporting soils. Therefore, it is imperative the
recommendations discussed in the Grading and Drainage section of the Earthwork
section this report be followed to reduce potential movement. As discussed in the
Grading and Drainage section of this report, surface drainage should be designed,
constructed and maintained to provide rapid removal of surface water runoff away from
the proposed buildings and pavements. Water should not be allowed to pond adjacent
to foundations or on pavements and conservative irrigation practices should be followed
to avoid wetting foundation/slab soils and pavement subgrade. Excessive wetting of
foundations/slab soils and subgrade can cause movement and distress to foundations,
floor slabs, concrete flatwork and pavements.
Foundations
The proposed buildings can be supported by a shallow, spread footing foundation
system. Design recommendations for foundations for the proposed structures and
related structural elements are presented in the Shallow Foundations section of
this report.
Floor Systems
We believe concrete slab-on-grade floor systems can be used for the proposed
buildings provided the soils are over-excavated to a depth of at least 12 inches below
the proposed floor slab and replaced with moisture conditioned, properly compacted
engineered fill. On-site soils are suitable as over-excavation backfill below floor slabs.
Design recommendations for floor slabs for the proposed structures and related
structural elements are presented in the Floor Slabs section of this report.
Pavements
Recommended Pavement thicknesses for this project include 4½ inches of asphalt
over no of aggregate base course in light-duty parking areas and 4½ inches of asphalt
over 6 inches of aggregate base course in heavy-duty drive lanes and loading areas.
Additional pavement section alternatives and discussion are presented in the report.
Seismic
Considerations
As presented in the Seismic Considerations section of this report, the International
Building Code, which refers to Section 20 of ASCE 7, indicates the seismic site
classification for this site is C.
Construction
Observation
and Testing
Close monitoring of the construction operations and implementing drainage
recommendations discussed herein will be critical in achieving the intended
foundation, slab and pavement performance. We therefore recommend that Terracon
be retained to monitor this portion of the work.
General
Comments
This section contains important information about the limitations of this geotechnical
engineering report.
1. If the reader is reviewing this report as a pdf, the topics (bold orange font) above can be used to access the
appropriate section of the report by simply clicking on the topic itself.
2. This summary is for convenience only. It should be used in conjunction with the entire report for design
making and design 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.
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INTRODUC TION
Geotechnical Engineering Report
Fort Collins Nissan and Kia Dealerships
West of South College Avenue and Crestridge Drive
Fort Collins, Colorado
Terracon Project No. 20215013
April 7, 2021
INTRODUCTION
This report presents the results of our subsurface exploration and geotechnical engineering
services performed for the proposed Fort Collins Nissan and Kia Dealerships to be located west
of the intersection of South College Avenue and Crestridge Drive in Fort Collins, Colorado. The
purpose of these services is to provide information and geotechnical engineering
recommendations relative to:
■ Subsurface soil and rock conditions ■ Foundation design and construction
■ Groundwater conditions ■ Floor system design and construction
■ Site preparation and earthwork ■ Seismic considerations
■ Demolition considerations ■ Lateral earth pressures
■ Excavation considerations ■ Pavement design and construction
The geotechnical engineering scope of services for this project i ncluded the advancement of eight
(8) test borings to depths ranging from approximately 15 to 30 feet below existing site grades.
Maps showing the site and boring locations are shown in the Site Location and Exploration
Plan sections, respectively. The results of the laboratory testing performed on soil and bedrock
samples obtained from the site during the field exploration are included on the boring logs and as
separate graphs in the Exploration Results section of this report.
SITE CONDITIONS
The following description of site conditions is derived from our site visit in association with the
field exploration and our review of publicly available geologic and topographic maps.
Item Description
Parcel Information
The project site is located west of the intersection of South College Avenue
and West Crestridge Drive in Fort Collins, Colorado. The approximate
Latitude/Longitude of the center of the site is 40.5066° N/105.0782°W (Please
refer to Site Location).
Existing
Improvements
The north portion of the site is currently vacant land with some two-track roads
and walking trails. The south portion of the site is currently occupied by an
existing Nissan Dealership and associated parking and drive areas.
Geotechnical Engineering Report
Fort Collins Nissan and Kia Dealerships ■ Fort Collins, Colorado
April 7, 2021 ■ Terracon Project No. 20215013
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Item Description
Surrounding
Developments
The site is bordered to the west by vacant land followed by an existing railroad
and single-family residential developments. To the north of the site is the
existing Fossil Creek followed by vacant land and single-family residential
developments. To the east and south of the site are commercial
developments followed by single-family residential developments
Current Ground
Cover
The current ground cover in areas of exploration consisted of native grasses
and weeds in the north portion of the site and concrete surfacing in the south
portion of the site.
Existing Topography
The south portion of the site is relatively flat. The north portion of the site has
rolling hills and generally slopes down from south to north towards Fossil
Creek.
PROJECT DESCRIPTION
Our final understanding of the project conditions is as follows:
Item Description
Information Provided
Project information was provided to us through the following:
■ Conversation with the client and project team.
■ Project concept plans, prepared by Infusion Architects and dated
February 26, 2021.
Project Description
We understand the project includes the demolition of the existing Nissan
dealership building, and associated parking and drive areas and the
construction of new Nissan and Kia dealerships. Parking and drive areas,
access lanes, a new roadway and new utilities are also planned for the project.
Proposed
Construction
We understand the project includes the following construction:
■ A 1 to 2-story new 40,630 square-foot Nissan dealership building,
anticipated to be supported on shallow foundations
■ A new 1 to 2-story 19,750 square-foot Kia dealership building,
anticipated to be supported on shallow foundations
■ Fill on the north side of the site to avoid steep grades in the planned
parking area
■ New inventory parking lot planned on west side of Venus Avenue
We understand the following may also be included in the project, however
exploration and recommendations for these aspects of the project were not
included in our base geotechnical engineering scope.
■ An option for turn lanes from South College Avenue onto Crestridge
Drive or an option to abandon Crestridge drive and create a private right
in/out of the Colorado Department of Transportation (CDOT) right of way
■ A new city street wrapping around the west side of the proposed site
connecting South College Avenue to Venus Avenue
Geotechnical Engineering Report
Fort Collins Nissan and Kia Dealerships ■ Fort Collins, Colorado
April 7, 2021 ■ Terracon Project No. 20215013
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Item Description
Maximum Loads
(assumed)
■ Columns: 50 to 100 kips
■ Walls: 1 to 3 kips per linear foot (klf)
■ Slabs: 150 pounds per square foot (psf)
Grading/Slopes
We anticipate minor cuts and fills on the order of 5 feet or less will be required
to achieve proposed grades on the majority of the site. We anticipate
significantly deeper fills, on the order of up to 20 to 30 feet could be required
on the north portion of the site in the area of the proposed parking area.
Below-grade
Structures We understand no below-grade are planned for this site.
Pavements
■ We assume both rigid (concrete) and flexible (asphalt) pavement
sections are being considered.
■ Parking and drive lanes were designed based on National Asphalt
Pavement Associations (NAPA) and the American Concrete Institute
(ACI).
If project information or assumptions vary from what is described above or if location of
construction changes, we should be contacted as soon as possible to confirm and/or modify our
recommendations accordingly.
GEOTECHNICAL CHARACTERIZATION
Subsurface Profile
We have developed a general characterization of the subsurface conditions based upon our
review of the subsurface exploration, laboratory data, geologic setting and our understanding of
the project. This characterization, termed GeoModel, forms the basis of our geotechnical
calculations and evaluation of site pre paration and foundation options. Conditions encountered at
each exploration point are indicated on the individual logs. The individual logs and the GeoModel
can be found in the Exploration Results section this report.
Model Layer Layer Name General Description Approximate Depth to
Bottom of Stratum
- Surface
Material
Concrete surfacing over aggregate
base course to native grasses and
weeds in clayey silty sand.
About 6 inches below
existing site grades.
1 Lean Clay Lean clay with sand to sandy lean clay,
brown to light brown, stiff to very stiff.
About 1 to 3 feet below
existing site grades.
2 Bedrock
Sandstone to siltstone bedrock with
trace amounts of clay, cemented
sandstone lenses throughout, light
brown to tan with orange and gray,
hard to very hard.
To the maximum depths of
exploration of about 15 to 30
feet below existing site
grades.
Geotechnical Engineering Report
Fort Collins Nissan and Kia Dealerships ■ Fort Collins, Colorado
April 7, 2021 ■ Terracon Project No. 20215013
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As noted in General Comments, this characterization is based upon widely spaced explora tion
points across the site and variations are likely.
Groundwater Conditions
The boreholes were observed while drilling and shortly after completion for the presence and level
of groundwater. The water levels observed in the boreholes are noted on the attached boring logs,
and are summarized below:
Boring Number Depth to Groundwater While Drilling, ft.
B-1 14
These observations represent short-term groundwater conditions at the time of and shortly after
the field exploration and may not be indicative of other times or at other locations. Groundwater
levels can be expected to fluctuate with varying seasonal and weather conditions, and other
factors.
Groundwater level fluctuations occur due to seasonal variations in the water levels present in
nearby water features, amount of rainfall, runoff and other factors not evident at the time the
borings was/were performed. Therefore, groundwater levels during construction or at other times
in the life of the structure(s) may be higher or lower than the level s indicated on the boring logs.
The possibility of groundwater level fluctuations should be considered when developing the
design and construction plans for the project.
Groundwater was not observed in the remaining borings while drilling, or for the sho rt duration the
borings could remain open. However, this does not necessarily mean the borings terminated above
groundwater, or the water levels summarized above are stable groundwater levels. Due to the low
permeability of the soils encountered in the borings, a relatively long period may be necessary for a
groundwater level to develop and stabilize in a borehole. Long term observations in piezometers or
observation wells sealed from the influence of surface water are often required to define groundwater
levels in materials of this type.
Laboratory Testing
A representative soil sample selected for swell -consolidation testing exhibited 2.3 percent swell
when wetted. The sandstone bedrock is considered to have low expansive potential or non -
expansive. Samples of site soils and bedrock selected for plasticity testing exhibited low to
moderate plasticity with liquid limits ranging from non -plastic to 32 and plasticity indices ranging
from non-plastic to 15. Laboratory test results are presented in the Exploration Results section
of this report.
Geotechnical Engineering Report
Fort Collins Nissan and Kia Dealerships ■ Fort Collins, Colorado
April 7, 2021 ■ Terracon Project No. 20215013
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GEOTECHNICAL OVERVIEW
Based on subsurface conditions encountered in the borings, the site appears suitable for the
proposed construction from a geotechnical point of view provided certain precautions and design
and construction recommendations described in this report are followed and the owner
understands the inherent risks associated with construction on sites underlain by expansive soils.
We have identified several geotechnical conditions that could impact design, construction and
performance of the proposed structures, pavements, and other site improvements. These
included shallow bedrock and expansive soils and areas that could have existing undocumented
fill. These conditions will require particular attention in project planning, design and during
construction and are discussed in greater detail in the following sections.
Shallow Bedrock
As previously stated, bedrock was measured at depths ranging from about 1 to 3 feet below
existing site grades. Bedrock was generally hard to very hard with cemented lenses throughout.
Excavation penetrating the bedrock may require the use of specialized heavy -duty equipment,
together with ripping or jack-hammering to advance the excavation a nd facilitate rock break-up
and removal. Consideration should be given to obtaining a unit price for difficult excavation in the
contract documents for the project.
Expansive Soils and Bedrock
As previously stated, a sample of on -site soils exhibited 2.3 percent swell upon wetting.
Expansive soils are anticipated to be encountered in the clay soils in the upper approximately 1
to 3 feet below existing site grades above the sandstone bedrock, these conditions constitute a
geologic hazard. This report provides recommendations to help mitigate the effects of soil
shrinkage and expansion. However, even if these procedures are followed, some movement and
cracking in the structures, pavements, and flatwork is possible. The severity of cracking and other
damage such as uneven floor slabs and flat work will probably increase if modification of the site
results in excessive wetting or drying of the expansive clays. Eliminating the risk of movement
and cosmetic distress is generally not feasible, but it may be possible to further reduce the risk of
movement if significantly more expensive measures are used during construction . It is imperative
the recommendations described in section Grading and Drainage section of the Earthwork
section of this report be followed to reduce potential movement. Clay soils used as backfill or fill
on the site should be probably moisture conditioned prior to placement to help mitigate the effects
of soil shrinkage and expansion.
Existing, Undocumented Fill
As previously noted, an existing Nissan dealership and associated parking and drive areas
currently occupy the south side of the site. Although not encountered in our exploratory borings,
based on the existing structures we anticipate existing undocum ented fill could be encountered
Geotechnical Engineering Report
Fort Collins Nissan and Kia Dealerships ■ Fort Collins, Colorado
April 7, 2021 ■ Terracon Project No. 20215013
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at the site, particularly under the existing building and associated structures. If fill is encountered,
we do not possess any information regarding whether the fill was placed under the observation
of a geotechnical enginee r. Undocumented fill can present a greater than normal risk of post -
construction movement of foundations, slabs, pavements and other site improvements supported
on or above these materials. Consequently, it is our opinion existing fill on the site (if any) should
not be relied upon for support and should be removed down to native soil, moisture conditioned
and recompacted prior to new fill placement and/or construction.
Foundation and Floor System Recommendations
The proposed buildings can be supported by a shallow, spread footing foundation system. Design
recommendations for foundations for the proposed structure s and related structural elements are
presented in the Shallow Foundations section of this report.
W e believe concrete slab-on-grade floor systems can be used for the proposed building s provided
the soils are over-excavated to a depth of at least 12 inches below the proposed floor slab and
replaced with moisture conditioned, properly compacted engineered fill. On-site soils are suitable as
over-excavation backfill below floor slabs. Design recommendations for floor slabs for the proposed
structures and related structural elements are presented in the Floor Slabs section of this report.
The General Comments section provides an understanding of the report limitations.
EARTHWORK
The following presents recommendations for site preparation, demolition, excavation, subgrade
preparation, fill materials, compaction requirements, utility trench backfill, grading and drainage
and exterior slab design and construction. Earthwork on the project should be observed and
evaluated by Terracon. Evaluation of earthwork should include observation and/or testing of over-
excavation, subgrade preparation, placement of engineered fills, subgrade stabilization and other
geotechnical conditions exposed during the construction of the project.
Site Preparation
Prior to placing any fill, strip and remove existing vegetation, topsoil, and any other deleterious
materials from the proposed construction areas.
Stripped organic materials should be wasted from the site or used to re -vegetate landscaped areas
or exposed slopes after completion of grading operations. P rior to the placement of fills, the site
should be graded to create a relatively level surface to receive fill, and to provide for a relatively
uniform thickness of fill beneath proposed structures.
Geotechnical Engineering Report
Fort Collins Nissan and Kia Dealerships ■ Fort Collins, Colorado
April 7, 2021 ■ Terracon Project No. 20215013
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If fill is placed in areas of the site where existing slopes are steeper than 5:1 (horizontal:vertical),
the area should be benched to reduce the potential for slippage between existing slopes and fills.
Benches should be wide enough to accommodate compaction and earth moving equipment, and
to allow placement of horizontal lifts of fill.
Demolition
Demolition of the existing Nissan dealership building, and associated parking and drive areas
should include complete removal of all foundation systems, below -grade structural elements,
pavements, and exterior flat work within the proposed construction area. This should include
removal of any utilities to be abandoned along with any loose utility trench backfill or loose backfill
found adjacent to existing foundations. All materials derived from the demolition of e xisting
structures and pavements should be removed from the site. The types of foundation systems
supporting the existing building are not known. If some or all of the existing buildings are supported
by drilled piers, the existing piers should be truncated a minimum depth of 3 feet below areas of
planned new construction.
Consideration could be given to re-using the asphalt and concrete provided the materials are
processed and uniformly blended with the on -site soils. Asphalt and/or concrete materials should
be processed to a maximum size of 2 inches and blended at a ratio of 30 percent asphalt/concrete
to 70 percent of on-site soils.
Excavation
It is anticipated that excavations for the proposed construction can be accomplished with
conventional earthmoving equipment.
As previously stated, shallow bedrock was encountered at depths of about 1 to 3 feet below existing
site grades. In addition, cemented lenses were encountered in the sandstone bedrock throughout
the site. Excavation penetrating the bedrock may require the use of specialized heavy-duty
equipment, together with ripping or jack-hammering advance the excavation and facilitate rock
break-up and removal. Consideration should be given to obtaining a unit price for difficult
excavation in the contract documents for the project.
The soils to be excavated can vary significantly across the site as their classifications are based
solely on the materials encountered in widely-spaced exploratory test borings. 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.
Although evidence of fills or underground facilities such as grease pits, septic tanks, vaults,
basements, and utilities was not observed during the site reconnaissance, such features could be
encountered during construction. If unexpected underground facilities are encountered, such
Geotechnical Engineering Report
Fort Collins Nissan and Kia Dealerships ■ Fort Collins, Colorado
April 7, 2021 ■ Terracon Project No. 20215013
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features should be removed, and the excavation thoroughly cleaned prior to backfill placement
and/or construction.
Any over-excavation that extends below the bottom of foundation elevation should extend laterally
beyond all edges of the foundations at least 8 inches per foot of over -excavation depth below the
foundation base elevation. The over-excavation should be backfilled to the foundation base
elevation in accordance with the recommendations presented in this report.
Depending upon depth of excavation and seasonal conditions, surface water infiltration and/or
groundwater may be encountered in excavations on the site. It is anticipated that pumping from
sumps may be utilized to control water within excavations.
The subgrade soil conditions should be evaluated during the excavation process and the stability
of the soils determined at that time by the contractors’ Competent Person. Slope inclinations flatter
than the OSHA maximum values may have to be used. The individual contractor(s) should be
made responsible for designing and constructing stable, temporary excavations as required to
maintain stability of both the excavation sides and bottom. All excavations should be sloped or
shored in the interest of safety following local, and federal regulations, including current OSHA
excavation and trench safety standards.
As a safety measure, it is recommended that all vehicles and soil piles be kept a minimum lateral
distance from the crest of the slope equal to the slope height. The exposed slope face should be
protected against the elements.
Subgrade Preparation
After the existing site features or existing topsoil has been removed from the construction area,
the top 10 inches of the exposed ground surface s hould be scarified, moisture conditioned, and
recompacted to at least 95 percent of the maximum dry unit weight as determined by ASTM D698
before any new fill or foundation or pavement is placed .
Although not anticipated, if pockets of soft, loose, or otherwise unsuitable materials are
encountered at the bottom of the foundation excavations and it is inconvenient to lower the
foundations, the proposed foundation elevations may be reestablished by over -excavating the
unsuitable soils and backfilling with c ompacted engineered fill or lean concrete.
Geotechnical Engineering Report
Fort Collins Nissan and Kia Dealerships ■ Fort Collins, Colorado
April 7, 2021 ■ Terracon Project No. 20215013
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After the bottom of the excavation has been compacted, engineered fill can be placed to bring the
building pad and pavement subgrade to the desired grade. Engineered fill should be placed in
accordance with the recommendations presented in subsequent sections of this report.
The stability of the subgrade may be affected by precipitation, repetitive construction traffic or
other factors. If unstable conditions develop, workability may be improved by scari fying and
drying. Alternatively, over-excavation of wet zones and replacement with granular materials may
be used, or crushed gravel and/or rock can be tracked or “crowded” into the unstable surface soil
until a stable working surface is attained. Lightweight excavation equipment may also be used to
reduce subgrade pumping.
Fill Materials
The on-site soils or approved granular and low plasticity cohesive imported materials may be used
as fill material. The earthwork contractor should expect significant mechanical processing and
moisture conditioning of the site soils and/or bedrock will be needed to achieve proper compaction
Bedrock excavated during site development and construction can be reused as fill provided the
material is broken down and thorough ly processed to a “soil-like” consistency, with no particles
greater than 2 inches in size.
Consideration could be given to re-using the asphalt and concrete from the demolition of the existing
structures, provided the materials are processed and uniformly blended with the on-site soils.
Asphalt and/or concrete materials should be processed to a maximum size of 2 inches and blended
at a ratio of 30 percent asphalt/concrete to 70 percent of on-site soils.
Imported soils (if required) should meet the following material property requirements:
Gradation Percent finer by weight (ASTM C136)
4” 100
Geotechnical Engineering Report
Fort Collins Nissan and Kia Dealerships ■ Fort Collins, Colorado
April 7, 2021 ■ Terracon Project No. 20215013
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Gradation Percent finer by weight (ASTM C136)
3” 70-100
No. 4 Sieve 30-100
No. 200 Sieve 50 (max.)
Soil Properties Values
Liquid Limit 35 (max.)
Plasticity Index 15 (max.)
Other import fill materia ls types may be suitable for use on the site depending upon proposed
application and location on the site, and could be tested and approved for use on a case -by-case
basis.
Compaction Requirements
We understand significant fills, on the order of about 15 f eet are anticipated on the north side of the
site. Engineered fill should be placed and compacted in horizontal lifts, using equipment and
procedures that will produce recommended moisture contents and densities throughout the lift.
Item Description
Fill lift thickness
9 inches or less in loose thickness when heavy, self-
propelled compaction equipment is used
4 to 6 inches in loose thickness when hand-guided
equipment (i.e. jumping jack or plate compactor) is used
Minimum compaction requirements 95 percent of the maximum dry unit weight as determined by
ASTM D698
Moisture content cohesive soil (clay) -1 to +3 % of the optimum moisture content
Moisture content cohesionless soil
(sand) -3 to +3 % of the optimum moisture content
1. We recommend engineered fill be tested for moisture content and compaction during placement. Should the
results of the in-place density tests indicate the specified moisture or compaction limits have not been met,
the area represented by the test should be reworked and retested as required until the specified moisture
and compaction requirements are achieved.
2. Specifically, moisture levels should be maintained low enough to allow for satisfactory compaction to be
achieved without the fill material pumping when proof rolled.
3. Moisture conditioned clay materials should not be allowed to dry out. A loss of moisture within these materials
could result in an increase in the material’s expansive potential. Subsequent wetting of these materials could
result in undesirable movement.
Utility Trench Backfill
All trench excavations should be made with sufficient working space to permit construction including
backfill placement and compaction.
Geotechnical Engineering Report
Fort Collins Nissan and Kia Dealerships ■ Fort Collins, Colorado
April 7, 2021 ■ Terracon Project No. 20215013
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All underground piping within or near the proposed structures should be designed with flexible
couplings, 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 imperative
that utility trenches be properly backfilled with relatively clean materials. If utility trenches are
backfilled with relatively clean granular material, they should be capped with at least 18 inches of
cohesive fill in non-pavement areas to reduce the infiltration and conveyance of surface water
through the trench backfill.
Utility trenches are a common source of water infiltration and migration. All utility trenches that
penetrate beneath the buildings should be effectively sealed to restrict water intrusion and flow
through the trenches that could migrate below the buildings. We recommend constructing an
effective clay “trench plug” that extends at least 5 feet out from the face of the building exteriors.
The plug material should consist of clay compacted at a water content at or above the soil’s optimum
water content. The clay fill should be placed to completely surround the utility line and be compacted
in accordance with recommendations in this report.
It is strongly recommended that a representative of Terracon provide full -time observation and
compaction testing of trench backfill within building and pavement areas.
Grading and Drainage
Grades must be adjusted to provide effective drainage away from the proposed building s and
existing buildings during construction and maintained throughout the life of the proposed project.
Infiltration of water into foundation excavations must be prevented during construction.
Landscape irrigation adjacent to foundations should be minimized or eliminated. Water permitted
to pond near or adjacent to the perimeter of the s tructures (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.
Exposed ground (if any) should be sloped at a minimum of 10 percent grade for at least 5 feet
beyond the perimeter of the proposed buildings, where possible. Lo cally, flatter grades may be
necessary to transition ADA access requirements for flatwork. The use of swales, chases and/or
area drains may be required to facilitate drainage in unpaved areas around the perimeter of the
buildings. Backfill against foundat ions and exterior walls should be properly compacted and free
of all construction debris to reduce the possibility of moisture infiltration. After construction of the
proposed buildings and prior to project completion, we recommend verification of final g rading be
performed to document positive drainage , as described above, has been achieved.
Flatwork and pavements will be subject to post -construction movement. Maximum grades
practical should be used for paving and flatwork to prevent areas where water c an pond. In
addition, allowances in final grades should take into consideration post -construction movement
Geotechnical Engineering Report
Fort Collins Nissan and Kia Dealerships ■ Fort Collins, Colorado
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of flatwork, particularly if such movement would be critical. Where paving or flatwork abuts the
structures, care should be taken that joints are properly sealed and maintained to prevent the
infiltration of surface water.
Planters located adjacent to structures (if any) should preferably be self -contained. Sprinkler
mains and spray heads should be located a minimum of 5 feet away from the buildin g line(s).
Low-volume, drip style landscaped irrigation should be used sparingly near the building. Roof
drains should discharge on to pavements or be extended away from the structures a minimum of
10 feet through the use of splash blocks or downspout ex tensions. A preferred alternative is to
have the roof drains discharge by solid pipe to storm sewers , a detention pond, or other
appropriate outfall.
Exterior Slab Design and Construction
Exterior slabs on-grade, exterior architectural features, and uti lities founded on, or in backfill or
the site soils will likely experience some movement due to the volume change of the material.
Potential movement could be reduced by:
◼ Minimizing moisture increases in the backfill;
◼ Controlling moisture-density during placement of the backfill;
◼ Using designs which allow vertical movement between the exterior features and
adjoining structural elements; and
◼ Placing control joints on relatively close centers.
Construction Observation and Testing
The earthwork efforts should be monitored under the direction of Terracon. Monitoring should
include documentation of adequate removal of vegetation and topsoil, proof rolling, and mitigation
of areas delineated by the proof roll to require mitigation. Each lift of compacted fill should be
tested, evaluated, and reworked as necessary until approved by Terracon prior to placement of
additional lifts.
In areas of foundation excavations, the bearing subgrade and exposed conditions at the base of
the recommended over-excavation should be evaluated under the direction of Terracon. In the
event that unanticipated conditions are encountered, Terracon should prescribe mitigation
options.
In addition to the documentation of the essential parameters necessary for construction, the
continuation of Terracon into the construction phase of the project provides the continuity to
maintain Terracon’s evaluation of subsurface conditions, including assessing variations and
associated design changes.
Geotechnical Engineering Report
Fort Collins Nissan and Kia Dealerships ■ Fort Collins, Colorado
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SHALLOW FOUNDATIONS
If the site has been prepa red in accordance with the requirements noted in Earthwork, the
following design parameters are applicable for shallow foundations.
Spread Footings - Design Recommendations
Description Values
Bearing material
Properly prepared on-site soil, or new, properly
placed engineered fill.1
Maximum net allowable bearing pressure2 3,000 psf
Minimum foundation dimensions Columns: 30 inches
Continuous: 18 inches
Lateral earth pressure coefficients3
Active, Ka = 0.21
Passive, Kp = 4.8
At-rest, Ko = 0.34
Sliding coefficient3 µ = 0.70
Moist soil unit weight ɣ = 125 pcf
Minimum embedment depth below finished
grade 4 30 inches
Estimated total movement 5 About 1 inch
Estimated differential movement 5 About ½ to ¾ of total movement
1. Based on the conceptual plans, we understand the buildings are planned for areas where significant fills are
not anticipated. The Shallow Foundation parameters in this table are for structures to be placed on native
bedrock and do not apply if buildings are placed on fills greater than 12 inches thick.
2. The recommended maximum net allowable bearing pressure assumes any unsuitable fill or soft/loose soils,
if encountered, will be over-excavated and replaced with properly compacted engineered fill. The design
bearing pressure applies to a dead load plus design live load condition. The design bearing pressure may
be increased by one-third when considering total loads that include wind or seismic conditions.
3. The lateral earth pressure coefficients and sliding coefficients are ultimate values and do not include a factor
of safety. The foundation designer should include the appropriate factors of safety.
4. For frost protection and to reduce the effects of seasonal moisture variations in the subgrade soils. The
minimum embedment depth is for perimeter footings beneath unheated areas and i s relative to lowest
adjacent finished grade, typically exterior grade. Interior column pads in heated areas should bear at least
12 inches below the adjacent grade (or top of the floor slab) for confinement of the bearing materials and to
develop the recommended bearing pressure.
5. The estimated movements presented above are based on the assumption that the maximum footing size is
8 feet for column footings and 2 feet for continuous footings. Larger foundation footprints will likely require
reduced net allowable soil bearing pressures to reduce risk for potential settlement.
Footings should be proportioned to reduce differential foundation movement. As discussed, total
movement resulting from the assumed structural loads is estimated to be on the order of about 1
inch. Additional foundation movements could occur if water from any source infiltrates the
foundation soils; therefore, proper drainage should be provided in the final design and during
Geotechnical Engineering Report
Fort Collins Nissan and Kia Dealerships ■ Fort Collins, Colorado
April 7, 2021 ■ Terracon Project No. 20215013
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construction and throughout the life of the structure. Fa ilure to maintain the proper drainage as
recommended in the Grading and Drainage section of the Earthwork section of this report will
nullify the movement estimates provided above.
Spread Footings - Construction Considerations
To reduce the potential of “pumping” and softening of the foundation soils at the foundation
bearing level and the requirement for corrective work, we suggest the foundation excavation for
the buildings be completed remotely with a track-hoe operating outside of the excavation limits.
Spread footing construction should only be considered if the estimated foundation movement can
be tolerated. Subgrade soils beneath footings should be moisture conditioned and compacted as
described in the Earthwork section of this report. The moisture content and compaction of
subgrade soils should be maintained until foundation construction.
Footings and foundation walls should be reinforced as necessary to reduce the potential for distre ss
caused by differential foundation movement.
Unstable surfaces will need to be stabilized prior to backfilling excavations and/or constructing
the building foundation, floor slab and/or project pavements. The use of angular rock, recycled
concrete and/or gravel pushed or “crowded” into the yielding subgrade is considered suitable
means of stabilizing the subgrade. The use of geosynthetic materials in conjunction with gravel
could also be considered and could be more cost effective.
Unstable subgrade conditions should be observed by Terracon to assess the subgrade and
provide suitable alternatives for stabilization. Stabilized areas should be proof rolled prior to
continuing construction to assess the stability of the subgrade.
Foundation excavations sho uld be observed by Terracon. If the soil conditions encountered differ
significantly from those presented in this report, supplemental recommendations will be required.
SEISMIC CONSIDERATIONS
The seismic design requirements for buildings and other structu res are based on Seismic Design
Category. Site Classification is required to determine the Seismic Design Category for a structure.
The Site Classification is based on the upper 100 feet of the site profile defined by a weighted
average value of either shear wave velocity, standard penetration resistance, or undrained shear
strength in accordance with Section 20.4 of ASCE 7 and t he International Building Code (IBC).
Based on the soil/bedrock properties encountered at the site and as described on the explora tion
logs and results, it is our professional opinion that the Seismic Site Classification is C.
Subsurface explorations at this site were extended to a maximum depth of 30 feet. The site
Geotechnical Engineering Report
Fort Collins Nissan and Kia Dealerships ■ Fort Collins, Colorado
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properties below the boring depth to 100 feet were estimated based on our experience and
knowledge of geologic conditions of the general area. Additional deeper borings or geophysical
testing may be performed to confirm the conditions below the current boring depth.
FLOOR SLABS
A slab-on-grade may be utilized for the inte rior floor system for the proposed buildings provided
the native clay soils and/or sandstone bedrock is over-excavated to a depth of at least 12 inches,
moisture conditioned, and compacted on -site soils. If the estimated movement cannot be
tolerated, a structurally-supported floor system, supported independent of the subgrade materials,
is recommended.
Subgrade soils beneath interior and exterior slabs and at the base of the over-excavation should
be scarified to a depth of at least 10 inches, moisture co nditioned and compacted. The moisture
content and compaction of subgrade soils should be maintained until slab construction.
Floor System - Design Recommendations
Even when bearing on properly prepared soils, movement of the slab -on-grade floor system is
possible should the subgrade soils undergo an increase in moisture content. We estimate
movement of about 1 inch is possible. If the owner cannot accept the risk of slab movement, a
structural floor should be used. If conventional slab-on-grade is utilized, the subgrade soils should
be over-excavated and prepared as presented in the Earthwork section of this report.
For structural design of concrete slabs-on-grade subjected to point loadings, a modulus of
subgrade reaction of 120 pounds per cubic inch (pci) may be used for floors supported on re -
compacted existing clay soils at the site. A modulus of 200 pci may be used for floors supported
on at least 1 foot of non -expansive, imported granular fill.
Additional floor slab design and construction recommendations are as follows:
◼ Positive separations and/or isolation joints should be provided between slabs and all
foundations, columns, or utility lines to allow independent movement.
◼ Control joints should be saw-cut in slabs in accordance with ACI Design Manual, Section
302.1R-37 8.3.12 (tooled control joints are not recommended) to control the location and
extent of cracking.
◼ Interior utility trench backfill placed beneath slabs should be compacted in accordance
with the recommendations presented in the Earthwork section of this report.
Geotechnical Engineering Report
Fort Collins Nissan and Kia Dealerships ■ Fort Collins, Colorado
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◼ Floor slabs should not be constructed on frozen subgrade.
◼ Other design and construction considerations, as outlined in the ACI Design Manual,
Section 302.1R are recommended.
Floor Systems - Construction Considerations
Movements of slabs-on-grade using the recommendations discussed in previous sections of this
report will likely be reduced and tend to be more uniform. The estimates discussed above assume
that the other recommendations in this report are followed. Additional movement could occur
should the subsurface soils become wetted to significant depths, which could result in potential
excessive movement causing uneven floor slabs and severe cracking. This could be due to over
watering of landscaping, poor drainage, improperly functioning drain systems, and/or broken utility
lines. Therefore, it is imperative that the recommendations presented in this report be followed.
PAVEMENTS
Pavements – Subgrade Preparation
On most project sites, the site grading is accomplished relatively early in the construction phase.
Fills are typically placed and compacted in a uniform manner. However, as construction
proceeds, the subgrade may be disturbed due to utilit y excavations, construction traffic,
desiccation, or rainfall/snow melt. As a result, the pavement subgrade may not be suitable for
pavement construction and corrective action will be required. The subgrade should be carefully
evaluated at the time of pavement construction for signs of disturbance or instability. We
recommend the pavement subgrade be thoroughly proof rolled with a loaded tandem-axle dump
truck prior to final grading and paving. All pavement areas should be moisture conditioned and
properly compacted to the recommendations in this report immediately prior to paving.
Pavements – Design Recommendations
Design of new privately-maintained pavements for the project has been based on the procedures
described by the National Asphalt Pavement Asso ciations (NAPA) and the American Concrete
Institute (ACI).
We assumed the following design parameters for NAPA flexible pavement thickness design:
◼ Automobile Parking Areas
• Class I - Parking stalls and parking lots for cars and pick -up trucks, with
Equivalent Single Axle Load (ESAL) up to 7,000 over 20 years
◼ Main Traffic Corridors
Geotechnical Engineering Report
Fort Collins Nissan and Kia Dealerships ■ Fort Collins, Colorado
April 7, 2021 ■ Terracon Project No. 20215013
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• Class II – Parking lots with a maximum of 10 trucks per day with Equivalent
Single Axle Load (ESAL) up to 27,000 over 20 years (Including trash trucks)
◼ Subgrade Soil Characteristics
• USCS Classification – SM to CL, classified by NAPA as medium to poor
We assumed the following design parameters for ACI rigid pavement thickness design based
upon the average daily truck traffic (ADTT):
◼ Automobile Parking Areas
• ACI Category A: Automobile parking with an ADTT of 1 over 20 years
◼ Main Traffic Corridors
• ACI Category A: Automobile parking area and service lanes with an ADTT of
up to 10 over 20 years
◼ Subgrade Soil Characteristics
• USCS Classification – SM to CL
◼ Concrete modulus of rupture value of 600 psi
We should be contacted to confirm and/or modify the recommendations contained herein if actual
traffic volumes differ from the assumed values shown above.
Recommended alternatives for flexible and rigid pavements are summarized for e ach traffic area
as follows:
Traffic Area Alternative
Recommended Pavement Thicknesses (Inches)
Asphaltic
Concrete
Surface
Aggregate
Base Course
Portland
Cement
Concrete
Total
Automobile Parking
(NAPA Class I and
ACI Category A)
A 4½ - - 4½
B - - 5 5
Main Traffic
Corridors
(NAPA Class II and
ACI Category A)
A 4½ 6 - 10½
B - - 6 6
Aggregate base course (if used on the site) should consist of a blend of sand and gravel which
meets strict specifications for quality and gradation. Use of materi als meeting Colorado
Department of Transportation (CDOT) Class 5 or 6 specifications is recommended for aggregate
base course. Aggregate base course should be placed in lifts not exceeding 6 inches and
compacted to a minimum of 95 percent of the maximum d ry unit weight as determined by ASTM
D698.
Geotechnical Engineering Report
Fort Collins Nissan and Kia Dealerships ■ Fort Collins, Colorado
April 7, 2021 ■ Terracon Project No. 20215013
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Asphaltic concrete should be composed of a mixture of aggregate, filler and additives (if required)
and approved bituminous material. The asphalt concrete should conform to approved mix
designs stating the Supe rpave properties, optimum asphalt content, job mix formula and
recommended mixing and placing temperatures. Aggregate used in asphalt concrete should
meet particular gradations. Material meeting CDOT Grading S or SX specifications or equivalent
is recommended for asphalt concrete. Mix designs should be submitted prior to construction to
verify their adequacy. Asphalt material should be placed in maximum 3 -inch lifts and compacted
within a range of 92 to 96 percent of the theoretical maximum (Rice) density (ASTM D2041).
Where rigid pavements are used, the concrete should be produced from an approved mix design
with the following minimum properties:
Properties Value
Compressive strength 4,000 psi
Cement type Type I or II portland cement
Entrained air content (%) 5 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. Longitudinal and transverse joints should be provided
as needed in concrete pavements for expansion/contraction and isolation per ACI 325. The
location and extent of joints should be based upon the final pavement geometry.
For areas subject to concentrated and repetitive loading conditions (if a ny) such as dumpster
pads, truck delivery docks and ingress/egress aprons, we recommend using a portland cement
concrete pavement with a thickness of at least 6 inches underlain by at least 4 inches of granular
base. Prior to placement of the granular base, the areas should be thoroughly proof rolled. For
dumpster pads, the concrete pavement area should be large enough to support the container and
tipping axle of the refuse truck.
Pavement performance is affected by its surroundings. In addition to providing preventive
maintenance, the civil engineer should consider the following recommendations in the design and
layout of pavements:
■ Site grades should slope a minimum of 2 percent away from the pavements;
■ The subgrade and the pavement surface have a minimum 2 percent slope to promote proper
surface drainage;
■ Consider appropriate edge drainage and pavement under drain systems;
■ Install pavement drainage surrounding areas anticipated for frequent wetting;
■ Install joint sealant and seal cracks immediately;
Geotechnical Engineering Report
Fort Collins Nissan and Kia Dealerships ■ Fort Collins, Colorado
April 7, 2021 ■ Terracon Project No. 20215013
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■ Seal all landscaped areas in, or adjacent to pavements to reduce moisture migration to
subgrade soils; and
■ Placing compacted, low permeability backfill against the exterior side of curb and gutter.
Pavements – Construction Considerations
Openings in pavement, such as landscape islands, are sources for water infiltration into
surrounding pavements. Water collects in the islands and migrates into the surrounding subgrade
soils thereby degrading support of the pavement. This is especially applicable for islands with
raised concrete curbs, irrigated foliage, and low permeability near -surface soils. The civil design
for the pavements with these conditions should include features to restrict or to collect and
discharge excess water from the islands. Examples of fe atures are edge drains connected to the
storm water collection system or other suitable outlet and impermeable barriers preventing lateral
migration of water such as a cutoff wall installed to a depth below the pavement structure.
Pavements – Maintenance
Preventative maintenance should be planned and provided for an ongoing pavement
management program in order to enhance future pavement performance. Preventive
maintenance consists of both localized maintenance (e.g. crack and joint 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.
CORROSIVITY
At the time this report was prepared, the laboratory testing for water-soluble sulfates had not been
completed. We will submit a supplemental section with the testing results and recommendations
once the testing has been completed.
GENERAL COMMENTS
Our analysis and opinions are based upon our understanding of the project, the geotechnical
conditions in the area, and the data obtained from our site exploration. Natural variations will occur
between exploration point locations or due to the modifying effec ts of construction or weather.
The nature and extent of such variations may not become evident unti l during or after construction.
Terracon should be retained as the Geotechnical Engineer, where noted in th is report, to provide
observation and testing services during pertinent construction phases. If variations appear, we
can provide further evaluation and supplemental recommendations. If variations are noted in the
absence of our observation and testing services on -site, we should be immediately notified so
that we can provide evaluation and supplemental recommendations.
Geotechnical Engineering Report
Fort Collins Nissan and Kia Dealerships ■ Fort Collins, Colorado
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Our Scope of Services 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.
Our services and any correspondence or collaboration through this system are intended for the
sole benefit and exclusive use of our client for specific application to the project discussed and
are accomplished in accordance with generally accepted geotechnical engineering practices with
no third-party beneficiaries intended. Any third-party access to services or correspondence is
solely for information purposes to support the services provided by Terracon to our client.
Reliance upon the services and any work product is limited to our client, and is not intended for
third parties. Any use or reliance of the p rovided information by third parties is done solely at their
own risk. No warranties, either express or implied, are intended or made.
Site characteristics as provided are for design purposes and not to estimate excavation cost. Any
use of our report in that regard is done at the sole risk of the excavating cost estimator as there
may be variations on the site that are not apparent in the data that could significantly impact
excavation cost. Any parties charged with estimating excavation costs should seek their own site
characterization for specific purposes to obtain the specific level of detail necessary for costing.
Site safety, and cost estimating including, excavation support, and dewatering
requirements/design are the responsibility of others. If changes in the nature, design, or location
of the project are planned, our conclusions and recommendations shall not be considered valid
unless we review the changes and either verify or modify our conclusions in writing.
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ATTACHMENTS
Contents:
EXPLORATION AND TESTING PROCEDURES
SITE LOCATION AND EXPLORATION PLANS
EXPLORATION RESULTS
SUPPORTING INFORMATION
Note: Refer to each individual Attachment for a listing of contents.
Geotechnical Engineering Report
Fort Collins Nissan and Kia Dealerships ■ Fort Collins, Colorado
April 7, 2021 ■ Terracon Project No. 20215013
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EXPLORATION AND TESTING PROCEDURES
Field Exploration
The field exploration program consist ed of the following:
Number of Borings Boring Depth (feet) Location
2 25 to 30 Planned new Nissan building area
2 20 to 25 Planned new Kia building area
4 15 Planned parking/drive area
Boring Layout and Elevations: We used handheld GPS equipment to locate borings with an
estimated horizontal accuracy of +/-20 feet. A ground surface elevation at each boring location
was obtained by Terracon by interpolation from a USGS topographic map.
Subsurface Exploration Procedures: We advanced soil borings with a truck-mounted drill rig
using continuous-flight, solid -stem augers. Three samples were obtained in the upper 10 feet of
each boring and at intervals of 5 feet thereafter. Soil sampling was performed using modified
California barrel and standard split -barrel sampling procedures. For the standard split -barrel
sampling procedure, a standard 2 -inch outer diameter split-barrel sampling spoon is driven into
the ground by a 140 -pound automatic hammer falling a distance of 30 inches. The number of
blows required to advance the sampling spoon the last 12 inches of a normal 18-inch penetration
is recorded as the Standard Penetration Test (SPT) resistance value. The SPT resistance values,
also referred to as N-values, are indicated on the boring logs at the test depths. For the modified
California barrel sampling procedure, a 2½-inch outer diameter split-barrel sampling spoon is
used for sampling. Modified California barrel sampling procedures are similar to standard split -
barrel sampling procedures; however, blow counts are typically recorded for 6 -inch intervals for a
total of 12 inches of penetration. The samples will be placed in appropriate containers, taken to
our soil laboratory for testing, and classified by a geotechnical engineer.
In addition, we observed and recorded groundwater levels during drilling observations. No
provisions were made to obtain delayed groundwater measurements.
Our exploration team prepared field boring logs as part of standard drilling operations including
sampling depths, penetration distances, and other relevant sampling information . Field logs
included visual classifications of materials encountered during drilling, and our interpretation of
subsurface conditions between samples. Final boring logs, prepared from field logs, represent
the geotechnical engineer's interpretation, and i nclude modifications based on observations and
laboratory test results.
Geotechnical Engineering Report
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Property Disturbance: Borings completed in the existing field were b ackfilled borings with auger
cuttings after completion. Borings completed in the existing parking area were backfil led with a
mixture of auger cuttings and bentonite chips and patched with concrete to match existing
surfaces. Our services did not include repair of the site beyond backfilling our boreholes, and
patching existing pavements/surfaces. Excess auger cuttings were dispersed in the general
vicinity of the boreholes. Because backfill material often settles below the surface after a period,
we recommend checking boreholes periodically and backfilling, if necessary. We can provide this
service, at your request.
Laboratory Testing
The project engineer reviewed field dat a and assigned various laboratory tests to better
understand the engineering properties of various soil and bedrock strata. Laboratory testing was
conducted in general accordance with applicable or other locally recognized standards.
Procedural standards noted in this report are for reference to methodology in general. In some
cases, variations to methods are applied as a result of local practice or professional judgement.
Testing was performed under the direction of a geotechnical engineer and included the following:
■ Visual classification ■ Moisture content
■ Dry density ■ Atterberg limits
■ Grain-size analysis ■ One-dimensional swell
■ Water-soluble sulfates
Our laboratory testing program includes examin ation of soil samples by an engineer. Based on
the material’s texture and plasticity, we described and classified soil samples in accordance with
the Unified Soil Classification System (USCS). Soil and bedrock samples obtained during our
field work will be disposed of after laboratory testing is complete unless a specific request is made
to temporarily store the samples for a longer period of time.
Bedrock samples obtained had rock classification conducted using locally accepted practices for
engineering purposes. Boring log rock classification is determined using the Description of Rock
Properties.
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SITE LOCATION AND EXPLORATION PLANS
Contents:
Site Location Plan
Exploration Plan
Note: All attachments are one page unless noted above.
SITE LOCATION
Fort Collins Nissan and Kia Dealerships ■ Fort Collins, Colorado
April 7, 2021 ■ Terracon Project No. 20215013
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above this text box, then paste your GIS Toolbox image.
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outside the table – please leave that alone. Limit editing to inside the table.
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it as desired, but try to keep to a single line of text to avoid reformatting the page.
SITE LOCA TION
DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY MICROSOFT BING MAPS
EXPLORATION PLAN
Fort Collins Nissan and Kia Dealerships ■ Fort Collins, Colorado
April 7, 2021 ■ Terracon Project No. 20215013
Note to Preparer: This is a large table with outside borders. Just click inside the table
above this text box, then paste your GIS Toolbox image.
When paragraph markers are turned on you may notice a line of hidden text above and
outside the table – please leave that alone. Limit editing to inside the table .
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it as desired, but try to keep to a single line of text to avoid reformatting the page.
EXPLORATION P LAN
DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY MICROSOFT BING MAPS
EXPLORATION RESULTS
Contents:
GeoModel
Boring Logs (8 pages)
Atterberg Limits
Grain Size Distribution (2 pages)
Consolidation/Swell
Note: All attachments are one page unless noted above.
4,980
4,985
4,990
4,995
5,000
5,005
5,010
5,015
5,020
5,025
ELEVATION(MSL)(feet)Fort Collins Nissan and Kia Dealerships Fort Collins, CO
Terracon Project No. 20215013
Layering shown on this figure has been developed by the
geotechnical engineer for purposes of modeling the subsurface
conditions as required for the subsequent geotechnical engineering
for this project.
Numbers adjacent to soil column indicate depth below ground
surface.
NOTES:
B-1B-2 B-3
B-4P-1
P-2
P-3
P-4
GEOMODEL
This is not a cross section. This is intended to display the Geotechnical Model only. See individual logs for more detailed conditions.
Groundwater levels are temporal. The levels shown are representative of the date
and time of our exploration. Significant changes are possible over time.
Water levels shown are as measured during and/or after drilling. In some cases,
boring advancement methods mask the presence/absence of groundwater. See
individual logs for details.
First Water Observation
LEGEND
Concrete
Aggregate Base Course
Sandy Lean Clay
Bedrock
Vegetative Layer
Lean Clay with Sand
Weathered Rock
Model Layer Layer Name General Description
Lean clay with sand to sandy lean clay, brown to light brown,1 stiff to very stiff.
Sandstone to siltstone bedrock with trace amounts of clay,
cemented sandstone lenses throughout, light brown to tan
with orange and gray, hard to very hard.
2
LEAN CLAY
BEDROCK
2
24.3
1
214
1
19.2
1
2
2
24.2
1
2
1
29.2
1
2
3
14.4
1
2
2.5
14.4
1
2
1
14.3
1
2
2.5
14.3
1
2
50/5"
50/2"
50/2"
50/3"
50/2"
50/3"
38
13.0
9.7
13.0
17.0
13.0
14.1
118
95
121
NP
CONCRETE, approximately 3 inches
AGGREGATE BASE COURSE, approximately 2 inches
SANDY LEAN CLAY, brown to light brown
SANDSTONE/SILTSTONE (SM), with cemented
sandstone lenses, light brown to tan, hard to very hard
gray brown
gray
Boring Terminated at 24.3 Feet
0.3
0.4
2.0
24.3
5023.5
5023.5
5022
4999.5
Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.THISBORINGLOGISNOTVALIDIFSEPARATEDFROMORIGINALREPORT.GEOSMARTLOG-NOWELL20215013FORTCOLLINSNISS.GPJTERRACON_DATATEMPLATE.GDT4/8/21WATERLEVELOBSERVATIONSDEPTH(Ft.)5
10
15
20 FIELDTESTRESULTSSWELL/LOAD(%/psf)PERCENTFINESWATERCONTENT(%)DRYUNITWEIGHT(pcf)ATTERBERG
LIMITS
LL-PL-PI
LOCATION See Exploration Plan
Latitude: 40.5062° Longitude: -105.0784°GRAPHICLOGMODELLAYERDEPTH ELEVATION (Ft.)
Surface Elev.: 5024 (Ft.)
Page 1 of 1
Advancement Method:
4-inch diameter, solid-stem augers
Abandonment Method:
Boring backfilled with a mixture of cuttings and bentonite chips
and patched with concrete
Notes:
Project No.: 20215013
Drill Rig: CME-55
BORING LOG NO. B-1
TCC CorporationCLIENT:
Windsor, CO
Driller: Drilling Engineers, Inc.
Boring Completed: 03-30-2021
PROJECT: Fort Collins Nissan and Kia Dealerships
Elevations were interpolated from USGS
topographic maps
See Exploration and Testing Procedures for a
description of field and laboratory procedures used
and additional data (If any).
See Supporting Information for explanation of
symbols and abbreviations.
West of South College Avenue and Crestridge Drive
Fort Collins, CO
SITE:
Boring Started: 03-30-2021
1901 Sharp Point Dr Ste C
Fort Collins, CO
14' while drilling
Boring backfilled immediately upon completion
WATER LEVEL OBSERVATIONS
1
2 SAMPLETYPE
21-50/1"
50/5"
Sample fell
apart upon
extraction
50/2"
50/2"
50/2"
2915.0
11.4
11.6
11.6
11.2
114
NP
CONCRETE, approximately 4 inches
AGGREGATE BASE COURSE, approximately 2 inches
SANDY LEAN CLAY, brown to light brown
SANDSTONE/SILTSTONE (SM), olive to tan/light brown
with white and orange, hard to very hard
light brown to olive brown
gray
Boring Terminated at 19.2 Feet
0.4
0.5
1.0
19.2
5022.5
5022.5
5022
5004
Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.THISBORINGLOGISNOTVALIDIFSEPARATEDFROMORIGINALREPORT.GEOSMARTLOG-NOWELL20215013FORTCOLLINSNISS.GPJTERRACON_DATATEMPLATE.GDT4/8/21WATERLEVELOBSERVATIONSSurface Elev.: 5023 (Ft.)
Page 1 of 1
Advancement Method:
4-inch diameter, solid-stem augers
Abandonment Method:
Boring backfilled with a mixture of cuttings and bentonite chips
and patched with concrete
Notes:
Project No.: 20215013
Drill Rig: CME-55
BORING LOG NO. B-2
TCC CorporationCLIENT:
Windsor, CO
Driller: Drilling Engineers, Inc.
Boring Completed: 03-30-2021
PROJECT: Fort Collins Nissan and Kia Dealerships
Elevations were interpolated from USGS
topographic maps
See Exploration and Testing Procedures for a
description of field and laboratory procedures used
and additional data (If any).
See Supporting Information for explanation of
symbols and abbreviations.
West of South College Avenue and Crestridge Drive
Fort Collins, CO
SITE:
Boring Started: 03-30-2021
1901 Sharp Point Dr Ste C
Fort Collins, CO
No free water observed while drilling DEPTH(Ft.)5
10
15 FIELDTESTRESULTSSWELL/LOAD(%/psf)PERCENTFINESWATERCONTENT(%)DRYUNITWEIGHT(pcf)ATTERBERG
LIMITS
LL-PL-PI
LOCATION See Exploration Plan
Latitude: 40.5060° Longitude: -105.0779°GRAPHICLOGMODELLAYERDEPTH ELEVATION (Ft.)
WATER LEVEL OBSERVATIONS
1
2 SAMPLETYPE
50/5"
Sample fell
apart upon
extraction
50/1"
50/3"
50/3"
50/2"
50/2"
22
6.0
6.0
10.7
12.1
11.6
12.4
106
118
NP
SANDY LEAN CLAY, brown to light brown
SANDSTONE/SILTSTONE, with cemented sandstone
lenses, light brown to red brown with orange brown and
white, hard to very hard
light brown to tan
with gray and dark gray
Boring Terminated at 24.2 Feet
2.0
24.2
5020
4998
Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.THISBORINGLOGISNOTVALIDIFSEPARATEDFROMORIGINALREPORT.GEOSMARTLOG-NOWELL20215013FORTCOLLINSNISS.GPJTERRACON_DATATEMPLATE.GDT4/8/21WATERLEVELOBSERVATIONSDEPTH(Ft.)5
10
15
20 FIELDTESTRESULTSSWELL/LOAD(%/psf)PERCENTFINESWATERCONTENT(%)DRYUNITWEIGHT(pcf)ATTERBERG
LIMITS
LL-PL-PI
LOCATION See Exploration Plan
Latitude: 40.5071° Longitude: -105.0781°GRAPHICLOGMODELLAYERDEPTH ELEVATION (Ft.)
Surface Elev.: 5022 (Ft.)
Page 1 of 1
Advancement Method:
4-inch diameter, solid-stem augers
Abandonment Method:
Boring backfilled with auger cuttings
Notes:
Project No.: 20215013
Drill Rig: CME-55
BORING LOG NO. B-3
TCC CorporationCLIENT:
Windsor, CO
Driller: Drilling Engineers, Inc.
Boring Completed: 03-30-2021
PROJECT: Fort Collins Nissan and Kia Dealerships
Elevations were interpolated from USGS
topographic maps
See Exploration and Testing Procedures for a
description of field and laboratory procedures used
and additional data (If any).
See Supporting Information for explanation of
symbols and abbreviations.
West of South College Avenue and Crestridge Drive
Fort Collins, CO
SITE:
Boring Started: 03-30-2021
1901 Sharp Point Dr Ste C
Fort Collins, CO
No free water observed while drilling
WATER LEVEL OBSERVATIONS
1
2 SAMPLETYPE
13-29-45
N=74
50/5"
Sample fell
apart upon
extraction
50/2"
50/2"
Sample fell
apart upon
extraction
50/3"
50/2"
50/2"
466.2
6.3
10.0
8.5
11.5
11.4
11.9
NP
NATIVE GRASSES AND WEEDS, with silty, clayey sand,
brown to dark brown
SANDY LEAN CLAY, brown to light brown
SANDSTONE/SILTSTONE (SM), light brown to tan, hard
to very hard
trace organics
with gray
Boring Terminated at 29.2 Feet
0.5
1.0
29.2
5019.5
5019
4991
Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.THISBORINGLOGISNOTVALIDIFSEPARATEDFROMORIGINALREPORT.GEOSMARTLOG-NOWELL20215013FORTCOLLINSNISS.GPJTERRACON_DATATEMPLATE.GDT4/8/21WATERLEVELOBSERVATIONSDEPTH(Ft.)5
10
15
20
25 FIELDTESTRESULTSSWELL/LOAD(%/psf)PERCENTFINESWATERCONTENT(%)DRYUNITWEIGHT(pcf)ATTERBERG
LIMITS
LL-PL-PI
LOCATION See Exploration Plan
Latitude: 40.5074° Longitude: -105.0788°GRAPHICLOGMODELLAYERDEPTH ELEVATION (Ft.)
Surface Elev.: 5020 (Ft.)
Page 1 of 1
Advancement Method:
4-inch diameter, solid-stem augers
Abandonment Method:
Boring backfilled with auger cuttings
Notes:
Project No.: 20215013
Drill Rig: CME-55
BORING LOG NO. B-4
TCC CorporationCLIENT:
Windsor, CO
Driller: Drilling Engineers, Inc.
Boring Completed: 03-30-2021
PROJECT: Fort Collins Nissan and Kia Dealerships
Elevations were interpolated from USGS
topographic maps
See Exploration and Testing Procedures for a
description of field and laboratory procedures used
and additional data (If any).
See Supporting Information for explanation of
symbols and abbreviations.
West of South College Avenue and Crestridge Drive
Fort Collins, CO
SITE:
Boring Started: 03-30-2021
1901 Sharp Point Dr Ste C
Fort Collins, CO
No free water observed while drilling
WATER LEVEL OBSERVATIONS
1
2 SAMPLETYPE
12-21
15-27-39
N=66
50/6"
Sample fell
apart upon
extraction
50/5"
+2.3/150 819.9
9.9
11.8
12.0
95 32-17-15
NATIVE GRASSES AND WEEDS, with silty, clayey sand,
brown to dark brown
LEAN CLAY WITH SAND, trace organics, brown, very
stiff
WEATHERED SANDSTONE, light brown, weathered to
firm
SANDSTONE, light brown to tan, hard to very hard
Boring Terminated at 14.4 Feet
0.5
3.0
5.0
14.4
5019.5
5017
5015
5005.5
Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.THISBORINGLOGISNOTVALIDIFSEPARATEDFROMORIGINALREPORT.GEOSMARTLOG-NOWELL20215013FORTCOLLINSNISS.GPJTERRACON_DATATEMPLATE.GDT4/8/21WATERLEVELOBSERVATIONSDEPTH(Ft.)5
10 FIELDTESTRESULTSSWELL/LOAD(%/psf)PERCENTFINESWATERCONTENT(%)DRYUNITWEIGHT(pcf)ATTERBERG
LIMITS
LL-PL-PI
LOCATION See Exploration Plan
Latitude: 40.5071° Longitude: -105.0802°GRAPHICLOGMODELLAYERDEPTH ELEVATION (Ft.)
Surface Elev.: 5020 (Ft.)
Page 1 of 1
Advancement Method:
4-inch diameter, solid-stem augers
Abandonment Method:
Boring backfilled with auger cuttings
Notes:
Project No.: 20215013
Drill Rig: CME-55
BORING LOG NO. P-1
TCC CorporationCLIENT:
Windsor, CO
Driller: Drilling Engineers, Inc.
Boring Completed: 03-30-2021
PROJECT: Fort Collins Nissan and Kia Dealerships
Elevations were interpolated from USGS
topographic maps
See Exploration and Testing Procedures for a
description of field and laboratory procedures used
and additional data (If any).
See Supporting Information for explanation of
symbols and abbreviations.
West of South College Avenue and Crestridge Drive
Fort Collins, CO
SITE:
Boring Started: 03-30-2021
1901 Sharp Point Dr Ste C
Fort Collins, CO
No free water observed while drilling
WATER LEVEL OBSERVATIONS
1
2 SAMPLETYPE
25-50/4"
50/6"
50/3"
Sample fell
apart upon
extraction
50/5"
55
14.3
13.9
13.3
14.1
119
NP
NATIVE GRASSES AND WEEDS, with silty, clayey sand,
brown to dark brown
SANDY LEAN CLAY, brown to light brown, very stiff
SILTSTONE/SANDSTONE (ML), with cemented
sandstone, light brown to tan, hard to very hard
with gray
Boring Terminated at 14.4 Feet
0.5
2.5
14.4
4996.5
4994.5
4982.5
Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.THISBORINGLOGISNOTVALIDIFSEPARATEDFROMORIGINALREPORT.GEOSMARTLOG-NOWELL20215013FORTCOLLINSNISS.GPJTERRACON_DATATEMPLATE.GDT4/8/21WATERLEVELOBSERVATIONSDEPTH(Ft.)5
10 FIELDTESTRESULTSSWELL/LOAD(%/psf)PERCENTFINESWATERCONTENT(%)DRYUNITWEIGHT(pcf)ATTERBERG
LIMITS
LL-PL-PI
LOCATION See Exploration Plan
Latitude: 40.5079° Longitude: -105.0789°GRAPHICLOGMODELLAYERDEPTH ELEVATION (Ft.)
Surface Elev.: 4997 (Ft.)
Page 1 of 1
Advancement Method:
4-inch diameter, solid-stem augers
Abandonment Method:
Boring backfilled with auger cuttings
Notes:
Project No.: 20215013
Drill Rig: CME-55
BORING LOG NO. P-2
TCC CorporationCLIENT:
Windsor, CO
Driller: Drilling Engineers, Inc.
Boring Completed: 03-30-2021
PROJECT: Fort Collins Nissan and Kia Dealerships
Elevations were interpolated from USGS
topographic maps
See Exploration and Testing Procedures for a
description of field and laboratory procedures used
and additional data (If any).
See Supporting Information for explanation of
symbols and abbreviations.
West of South College Avenue and Crestridge Drive
Fort Collins, CO
SITE:
Boring Started: 03-30-2021
1901 Sharp Point Dr Ste C
Fort Collins, CO
No free water observed while drilling
WATER LEVEL OBSERVATIONS
1
2 SAMPLETYPE
50/1"
Sample fell
apart upon
extraction
50/3"
50/2"
Sample fel apart
upon extraction
50/3"
29
8.0
12.8
11.2
12.8
NP
NATIVE GRASSES AND WEEDS, with silty, clayey sand,
brown to dark brown
SANDY LEAN CLAY, brown to light brown, very stiff
SILTSTONE/SANDSTONE (GM), with cemented
sandstone lenses, light brown to tan, hard to very hard
gray
Boring Terminated at 14.3 Feet
0.5
1.0
14.3
5005.5
5005
4991.5
Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.THISBORINGLOGISNOTVALIDIFSEPARATEDFROMORIGINALREPORT.GEOSMARTLOG-NOWELL20215013FORTCOLLINSNISS.GPJTERRACON_DATATEMPLATE.GDT4/8/21WATERLEVELOBSERVATIONSDEPTH(Ft.)5
10 FIELDTESTRESULTSSWELL/LOAD(%/psf)PERCENTFINESWATERCONTENT(%)DRYUNITWEIGHT(pcf)ATTERBERG
LIMITS
LL-PL-PI
LOCATION See Exploration Plan
Latitude: 40.5083° Longitude: -105.0782°GRAPHICLOGMODELLAYERDEPTH ELEVATION (Ft.)
Surface Elev.: 5006 (Ft.)
Page 1 of 1
Advancement Method:
4-inch diameter, solid-stem augers
Abandonment Method:
Boring backfilled with auger cuttings
Notes:
Project No.: 20215013
Drill Rig: CME-55
BORING LOG NO. P-3
TCC CorporationCLIENT:
Windsor, CO
Driller: Drilling Engineers, Inc.
Boring Completed: 03-30-2021
PROJECT: Fort Collins Nissan and Kia Dealerships
Elevations were interpolated from USGS
topographic maps
See Exploration and Testing Procedures for a
description of field and laboratory procedures used
and additional data (If any).
See Supporting Information for explanation of
symbols and abbreviations.
West of South College Avenue and Crestridge Drive
Fort Collins, CO
SITE:
Boring Started: 03-30-2021
1901 Sharp Point Dr Ste C
Fort Collins, CO
No free water observed while drilling
WATER LEVEL OBSERVATIONS
1
2 SAMPLETYPE
21-50/5"
Sample fell
apart upon
extraction
50/5"
50/3"
Sample fell
apart upon
extraction
50/3"
35
5.7
6.8
9.1
9.2
NP
NATIVE GRASSES AND WEEDS, with silty, clayey sand,
brown to dark brown
SANDY LEAN CLAY, brown to light brown, very stiff
SANDSTONE/SILTSTONE (SM), trace clay and
cemented sandstone lenses, light brown to tan, hard to very
hard
Boring Terminated at 14.3 Feet
0.5
2.5
14.3
5021.5
5019.5
5007.5
Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.THISBORINGLOGISNOTVALIDIFSEPARATEDFROMORIGINALREPORT.GEOSMARTLOG-NOWELL20215013FORTCOLLINSNISS.GPJTERRACON_DATATEMPLATE.GDT4/8/21WATERLEVELOBSERVATIONSDEPTH(Ft.)5
10 FIELDTESTRESULTSSWELL/LOAD(%/psf)PERCENTFINESWATERCONTENT(%)DRYUNITWEIGHT(pcf)ATTERBERG
LIMITS
LL-PL-PI
LOCATION See Exploration Plan
Latitude: 40.5077° Longitude: -105.0779°GRAPHICLOGMODELLAYERDEPTH ELEVATION (Ft.)
Surface Elev.: 5022 (Ft.)
Page 1 of 1
Advancement Method:
4-inch diameter, solid-stem augers
Abandonment Method:
Boring backfilled with auger cuttings
Notes:
Project No.: 20215013
Drill Rig: CME-55
BORING LOG NO. P-4
TCC CorporationCLIENT:
Windsor, CO
Driller: Drilling Engineers, Inc.
Boring Completed: 03-30-2021
PROJECT: Fort Collins Nissan and Kia Dealerships
Elevations were interpolated from USGS
topographic maps
See Exploration and Testing Procedures for a
description of field and laboratory procedures used
and additional data (If any).
See Supporting Information for explanation of
symbols and abbreviations.
West of South College Avenue and Crestridge Drive
Fort Collins, CO
SITE:
Boring Started: 03-30-2021
1901 Sharp Point Dr Ste C
Fort Collins, CO
No free water observed while drilling
WATER LEVEL OBSERVATIONS
1
2 SAMPLETYPE
0
10
20
30
40
50
60
0 20 40 60 80 100CHorOHCLorOLML or OL
MH or OH"U"Line"A "LineATTERBERG LIMITS RESULTS
ASTM D4318
P
L
A
S
T
I
C
I
T
Y
I
N
D
E
X
LIQUID LIMIT
PROJECT NUMBER: 20215013
SITE: West of South College Avenue and
Crestridge Drive
Fort Collins, CO
PROJECT: Fort Collins Nissan and Kia
Dealerships
CLIENT: TCC Corporation
Windsor, CO
1901 Sharp Point Dr Ste C
Fort Collins, CO
LABORATORYTESTSARENOTVALIDIFSEPARATEDFROMORIGINALREPORT.ATTERBERGLIMITS20215013FORTCOLLINSNISS.GPJTERRACON_DATATEMPLATE.GDT4/7/21NP
NP
NP
NP
32
NP
NP
NP
NP
NP
NP
NP
17
NP
NP
NP
NP
NP
NP
NP
15
NP
NP
NP
PIPLLLBoring ID Depth
B-1
B-2
B-3
B-4
P-1
P-2
P-3
P-4
38.1
28.7
22.2
45.7
81.2
54.8
28.8
35.3
Fines
9 - 9.2
2 - 2.7
9 - 9.3
2 - 3.5
2 - 3
4 - 4.5
4 - 4.3
9 - 9.3
SM
SM
GM
SM
CL
ML
GM
SM
SANDSTONE/SILTSTONE with CEMENTED LENSES
SANDSTONE/SILTSTONE
SANDSTONE/SILTSTONE with CEMENTED LENSES
SANDSTONE/SILTSTONE
LEAN CLAY with SAND
SILTSTONE/SANDSTONE with CEMENTED LENSES
SILTSTONE/SANDSTONE with CEMENTED LENSES
SANDSTONE/SILTSTONE with CEMENTED LENSES
DescriptionUSCS
CL-ML
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
30 40 501.5 200681014413/4 1/2 60
GRAIN SIZE IN MILLIMETERSPERCENTFINERBYWEIGHT HYDROMETERU.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS
4 3/8 3 100 14032
GRAIN SIZE DISTRIBUTION
ASTM D422 / ASTM C136
6 16 20
PROJECT NUMBER: 20215013
SITE: West of South College Avenue and
Crestridge Drive
Fort Collins, CO
PROJECT: Fort Collins Nissan and Kia
Dealerships
CLIENT: TCC Corporation
Windsor, CO
1901 Sharp Point Dr Ste C
Fort Collins, CO
LABORATORYTESTSARENOTVALIDIFSEPARATEDFROMORIGINALREPORT.GRAINSIZE:USCS-220215013FORTCOLLINSNISS.GPJTERRACON_DATATEMPLATE.GDT4/7/21mediumcoarsecoarsefine fineCOBBLESGRAVELSAND SILT OR CLAY
B-1
B-2
B-3
B-4
P-1
SANDSTONE/SILTSTONE with CEMENTED LENSES (SM)
SANDSTONE/SILTSTONE (SM)
SANDSTONE/SILTSTONE with CEMENTED LENSES (GM)
SANDSTONE/SILTSTONE (SM)
LEAN CLAY with SAND (CL)
NP
NP
NP
NP
32
NP
NP
NP
NP
15
NP
NP
NP
NP
17
9 - 9.2
2 - 2.7
9 - 9.3
2 - 3.5
2 - 3
13.0
15.0
10.7
6.2
9.9
B-1
B-2
B-3
B-4
P-1
38.1
28.7
22.2
45.7
81.2
9 - 9.2
2 - 2.7
9 - 9.3
2 - 3.5
2 - 3
24.5
4.1
39.8
0.0
0.0
37.5
67.2
38.0
54.2
18.8
37.5
12.5
37.5
9.5
9.5
0.135
0.182
4.601
0.093
0.078
0.096
Boring ID Depth WC (%)LL PL PI Cc Cu
%Clay%Fines%Silt%Sand%Gravel Boring ID Depth D100 D60 D30 D10
USCS Classification
%Cobbles
0.0
0.0
0.0
0.0
0.0
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
30 40 501.5 200681014413/4 1/2 60
GRAIN SIZE IN MILLIMETERSPERCENTFINERBYWEIGHT HYDROMETERU.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS
4 3/8 3 100 14032
GRAIN SIZE DISTRIBUTION
ASTM D422 / ASTM C136
6 16 20
PROJECT NUMBER: 20215013
SITE: West of South College Avenue and
Crestridge Drive
Fort Collins, CO
PROJECT: Fort Collins Nissan and Kia
Dealerships
CLIENT: TCC Corporation
Windsor, CO
1901 Sharp Point Dr Ste C
Fort Collins, CO
LABORATORYTESTSARENOTVALIDIFSEPARATEDFROMORIGINALREPORT.GRAINSIZE:USCS-220215013FORTCOLLINSNISS.GPJTERRACON_DATATEMPLATE.GDT4/7/21mediumcoarsecoarsefine fineCOBBLESGRAVELSAND SILT OR CLAY
P-2
P-3
P-4
SILTSTONE/SANDSTONE with CEMENTED LENSES (ML)
SILTSTONE/SANDSTONE with CEMENTED LENSES (GM)
SANDSTONE/SILTSTONE with CEMENTED LENSES (SM)
NP
NP
NP
NP
NP
NP
NP
NP
NP
4 - 4.5
4 - 4.3
9 - 9.3
13.9
12.8
9.1
P-2
P-3
P-4
54.8
28.8
35.3
4 - 4.5
4 - 4.3
9 - 9.3
7.9
35.6
29.9
37.4
35.6
34.8
25
25
25
0.086
2.802
0.21
0.078
Boring ID Depth WC (%)LL PL PI Cc Cu
%Clay%Fines%Silt%Sand%Gravel Boring ID Depth D100 D60 D30 D10
USCS Classification
%Cobbles
0.0
0.0
0.0
-10
-8
-6
-4
-2
0
2
4
100 1,000 10,000AXIALSTRAIN,%PRESSURE, psf
NOTES: Sample exhibited 2.3 percent swell upon wetting under an applied pressure of 150 psf.
SWELL CONSOLIDATION TEST
ASTM D4546
PROJECT NUMBER: 20215013
SITE: West of South College Avenue and
Crestridge Drive
Fort Collins, CO
PROJECT: Fort Collins Nissan and Kia
Dealerships
CLIENT: TCC Corporation
Windsor, CO
1901 Sharp Point Dr Ste C
Fort Collins, CO
LABORATORYTESTSARENOTVALIDIFSEPARATEDFROMORIGINALREPORT.TC_CONSOL_STRAIN-USCS20215013FORTCOLLINSNISS.GPJTERRACON_DATATEMPLATE.GDT4/7/21P-1 LEAN CLAY with SAND(CL)2 - 3 ft 95 9.9
Specimen Identification Classification , pcf WC, %
SUPPORTING INFORMATION
Contents:
General Notes
Unified Soil Classification System
Description of Rock Properties
Note: All attachments are one page unless noted above.
Fort Collins Nissan and Kia Dealerships Fort Collins, CO
Terracon Project No. 20215013
2,000 to 4,000
Unconfined
Compressive
Strength
Qu, (psf)
less than 500
500 to 1,000
1,000 to 2,000
4,000 to 8,000
> 8,000
Modified
California
Ring
Sampler
Standard
Penetration
Test
N
(HP)
(T)
(DCP)
UC
(PID)
(OVA)
Standard Penetration Test
Resistance (Blows/Ft.)
Hand Penetrometer
Torvane
Dynamic Cone Penetrometer
Unconfined Compressive
Strength
Photo-Ionization Detector
Organic Vapor Analyzer
SAMPLING WATER LEVEL FIELD TESTS
GENERAL NOTES
DESCRIPTION OF SYMBOLS AND ABBREVIATIONS
Water levels indicated on the soil boring logs are
the levels measured in the borehole at the times
indicated. Groundwater level variations will occur
over time. In low permeability soils, accurate
determination of groundwater levels is not possible
with short term water level observations.
Water Initially
Encountered
Water Level After a
Specified Period of Time
Water Level After
a Specified Period of Time
Cave In
Encountered
Exploration point locations as shown on the Exploration Plan and as noted on the soil boring logs in the form of Latitude and
Longitude are approximate. See Exploration and Testing Procedures in the report for the methods used to locate the
exploration points for this project. Surface elevation data annotated with +/- indicates that no actual topographical survey was
conducted to confirm the surface elevation. Instead, the surface elevation was approximately determined from topographic
maps of the area.
LOCATION AND ELEVATION NOTES
Soil classification as noted on the soil boring logs is based Unified Soil Classification System. Where sufficient laboratory data
exist to classify the soils consistent with ASTM D2487 "Classification of Soils for Engineering Purposes" this procedure is used.
ASTM D2488 "Description and Identification of Soils (Visual-Manual Procedure)" is also used to classify the soils, particularly
where insufficient laboratory data exist to classify the soils in accordance with ASTM D2487. In addition to USCS classification,
coarse grained soils are classified on the basis of their in-place relative density, and fine-grained soils are classified on the basis
of their consistency. See "Strength Terms" table below for details. The ASTM standards noted above are for reference to
methodology in general. In some cases, variations to methods are applied as a result of local practice or professional judgment.
DESCRIPTIVE SOIL CLASSIFICATION
The soil boring logs contained within this document are intended for application to the project as described in this document.
Use of these soil boring logs for any other purpose may not be appropriate.
RELEVANCE OF SOIL BORING LOG
STRENGTH TERMS
30 - 50
> 50
5 - 9
10 - 18
Descriptive
Term
(Consistency)
8 - 15
> 30
Ring
Sampler
Blows/Ft.
10 - 29
> 99
Medium Hard
< 3
3 - 4
19 - 42
2 - 4
BEDROCK
Standard
Penetration
or N-Value
Blows/Ft.
0 - 3Very Loose Very Soft
(More than 50% retained on No. 200
sieve.)
Density determined by Standard
Penetration Resistance
(50% or more passing the No. 200 sieve.)
Consistency determined by laboratory shear strength testing,
field visual-manual procedures or standard penetration
resistance
RELATIVE DENSITY OF COARSE-GRAINED SOILS
30 - 49
50 - 79
>79
Descriptive
Term
(Consistency)
Firm
< 20 Weathered
Hard
< 30
30 - 49
50 - 89
90 - 119
> 11915 - 30
Standard
Penetration or
N-Value
Blows/Ft.
0 - 1
4 - 8
Very Hard
Ring
Sampler
Blows/Ft.
Ring
Sampler
Blows/Ft.
Soft
Medium Stiff
Stiff
Very Stiff
Hard
CONSISTENCY OF FINE-GRAINED SOILS
Standard
Penetration
or N-Value
Blows/Ft.
> 42
Loose
Medium Dense
Dense
Very Dense
7 - 18
19 - 58
Descriptive Term
(Density)
0 - 6
4 - 9
59 - 98
_
20 - 29
UNIFIED SOIL CLASSIFICATION SYSTEM
UNIFIED SOI L CLASSI FICATI ON SYSTEM
Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A
Soil Classification
Group
Symbol Group Name B
Coarse-Grained Soils:
More than 50% retained
on No. 200 sieve
Gravels:
More than 50% of
coarse fraction
retained on No. 4 sieve
Clean Gravels:
Less than 5% fines C
Cu 4 and 1 Cc 3 E GW Well-graded gravel F
Cu 4 and/or [Cc<1 or Cc>3.0] E GP Poorly graded gravel F
Gravels with Fines:
More than 12% fines C
Fines classify as ML or MH GM Silty gravel F, G, H
Fines classify as CL or CH GC Clayey gravel F, G, H
Sands:
50% or more of coarse
fraction passes No. 4
sieve
Clean Sands:
Less than 5% fines D
Cu 6 and 1 Cc 3 E SW Well-graded sand I
Cu 6 and/or [Cc<1 or Cc>3.0] E SP Poorly graded sand I
Sands with Fines:
More than 12% fines D
Fines classify as ML or MH SM Silty sand G, H, I
Fines classify as CL or CH SC Clayey sand G, H, I
Fine-Grained Soils:
50% or more passes the
No. 200 sieve
Silts and Clays:
Liquid limit less than 50
Inorganic: PI 7 and plots on or above “A”
line J
CL Lean clay K, L, M
PI 4 or plots below “A” line J ML Silt K, L, M
Organic: Liquid limit - oven dried 0.75 OL Organic clay K, L, M, N
Liquid limit - not dried Organic silt K, L, M, O
Silts and Clays:
Liquid limit 50 or more
Inorganic: PI plots on or above “A” line CH Fat clay K, L, M
PI plots below “A” line MH Elastic Silt K, L, M
Organic: Liquid limit - oven dried 0.75 OH Organic clay K, L, M, P
Liquid limit - not dried Organic silt K, 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-inch (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 =
6010
2
30
DxD
)(D
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.
H If 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.
DESCRIPTION OF ROCK PROPERTIES
ROCK VERSION 1
WEATHERING
Term Description
Unweathered No visible sign of rock material weathering, perhaps slight discoloration on major discontinuity surfaces.
Slightly
weathered
Discoloration indicates weathering of rock material and discontinuity surfaces. All the rock material may be
discolored by weathering and may be somewhat weaker externally than in its fresh condition.
Moderately
weathered
Less than half of the rock material is decomposed and/or disintegrated to a soil. Fresh or discolored rock is
present either as a continuous framework or as corestones.
Highly
weathered
More than half of the rock material is decomposed and/or disintegrated to a soil. Fresh or discolored rock is
present either as a discontinuous framework or as corestones.
Completely
weathered All rock material is decomposed and/or disintegrated to soil. The original mass structure is still largely intact.
Residual soil All rock material is converted to soil. The mass structure and material fabric are destroyed. There is a large
change in volume, but the soil has not been significantly transported.
STRENGTH OR HARDNESS
Description Field Identification Uniaxial Compressive
Strength, psi (MPa)
Extremely weak Indented by thumbnail 40-150 (0.3-1)
Very weak Crumbles under firm blows with point of geological hammer, can be
peeled by a pocket knife 150-700 (1-5)
Weak rock Can be peeled by a pocket knife with difficulty, shallow indentations
made by firm blow with point of geological hammer 700-4,000 (5-30)
Medium strong Cannot be scraped or peeled with a pocket knife, specimen can be
fractured with single firm blow of geological hammer 4,000-7,000 (30-50)
Strong rock Specimen requires more than one blow of geological hammer to
fracture it 7,000-15,000 (50-100)
Very strong Specimen requires many blows of geological hammer to fracture it 15,000-36,000 (100-250)
Extremely strong Specimen can only be chipped with geological hammer >36,000 (>250)
DISCONTINUITY DESCRIPTION
Fracture Spacing (Joints, Faults, Other Fractures) Bedding Spacing (May Include Foliation or Banding)
Description Spacing Description Spacing
Extremely close < ¾ in (<19 mm) Laminated < ½ in (<12 mm)
Very close ¾ in – 2-1/2 in (19 - 60 mm) Very thin ½ in – 2 in (12 – 50 mm)
Close 2-1/2 in – 8 in (60 – 200 mm) Thin 2 in – 1 ft. (50 – 300 mm)
Moderate 8 in – 2 ft. (200 – 600 mm) Medium 1 ft. – 3 ft. (300 – 900 mm)
Wide 2 ft. – 6 ft. (600 mm – 2.0 m) Thick 3 ft. – 10 ft. (900 mm – 3 m)
Very Wide 6 ft. – 20 ft. (2.0 – 6 m) Massive > 10 ft. (3 m)
Discontinuity Orientation (Angle): Measure the angle of discontinuity relative to a plane perpendicular to the longitudinal axis of the
core. (For most cases, the core axis is vertical; therefore, the plane perpendicular to the core axis is horizontal.) For example, a
horizontal bedding plane would have a 0-degree angle.
ROCK QUALITY DESIGNATION (RQD) 1
Description RQD Value (%)
Very Poor 0 - 25
Poor 25 – 50
Fair 50 – 75
Good 75 – 90
Excellent 90 - 100
1. The combined length of all sound and intact core segments equal to or greater than 4 inches in length, expressed as a
percentage of the total core run length.
Reference: U.S. Department of Transportation, Federal Hig hway Administration, Publication No FHWA-NHI-10-034, December 2009
Technical Manual for Design and Construction of Road Tunnels – Civil Elements