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REPORT TOPICS
REPORT TOPICS
REPORT SUMMARY ....................................................................................................... i
INTRODUCTION ............................................................................................................. 1
SITE CONDITIONS ......................................................................................................... 1
PROJECT DESCRIPTION .............................................................................................. 2
GEOTECHNICAL CHARACTERIZATION ...................................................................... 2
CORROSIVITY................................................................................................................ 3
GEOTECHNICAL OVERVIEW ....................................................................................... 4
EARTHWORK................................................................................................................. 4
PAVEMENTS .................................................................................................................. 7
GENERAL COMMENTS ............................................................................................... 11
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ATTACHMENTS
SITE LOCATION AND EXPLORATION PLANS
EXPLORATION RESULTS (EXPLORATION AND TESTING PROCEDURES, Boring
Logs and Laboratory Data)
SUPPORTING INFORMATION (General Notes and Unified Soil Classification System)
Geotechnical Engineering Report
City-maintained Roadways at Crowne at Old Town North ■ Fort Collins, Colorado
Revised August 22, 2018 ■ Terracon Project No. 20185095 (revised)
Responsive ■ Resourceful ■ Reliable i
REPORT SUMMARY
Topic
1
Overview Statement
2
Project
Overview
A geotechnical exploration has been performed for Lupine Drive which is a city-
maintained roadway planned at the Crowne at Old Town North project to be constructed
southwest of the intersection of Conifer Street and Blue Spruce Drive in Fort Collins,
Colorado. Two (2) borings were performed to depths of approximately 10½ feet below
existing site grades.
Subsurface
Conditions
Subsurface conditions encountered in our exploratory borings generally consisted of
about 4 to 5 feet of fill consisting of sandy lean clay over well graded sand and gravel
with varying amounts of silt and clay, which extended to the maximum depths of
exploration of about 10 feet below existing site grades. Boring logs are presented in
the Exploration Results section of this report.
Groundwater
Conditions
Groundwater was not encountered in any of our test borings at the time of drilling.
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. We do not anticipate groundwater will significantly impact the
proposed construction.
Geotechnical
Concerns
Expansive soils are present on this site and 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 pavements is possible. 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, such as treating the subgrade soils with fly ash. 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.
Ground
Improvements
Results of swell testing indicated swell mitigation may be necessary at this site. We
believe swell-mitigation could be completed by properly moisture conditioning the top
12 inches of finished pavement subgrade prior to placement of aggregate base course
and asphalt materials. Even with properly prepared and compacted soils, the possibility
of damage to the pavements, such as uneven areas and cracking is possible. As an
alternative, we believe an initial application of lime and a secondary application of fly
ash could be used to treat the upper 12 inches of the on-site soil for swell-mitigation.
Grading and
Drainage
The amount of movement of pavements 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.
Pavements
Recommended Pavement thicknesses for this project include 5½ inches of asphalt
over 10 inches of aggregate base course on Lupine Drive west of Jerome Street and 5
inches of asphalt over 8 inches of aggregate base course on Lupine Drive east of
Geotechnical Engineering Report
City-maintained Roadways at Crowne at Old Town North ■ Fort Collins, Colorado
Revised August 22, 2018 ■ Terracon Project No. 20185095 (revised)
Responsive ■ Resourceful ■ Reliable ii
Topic
1
Overview Statement
2
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
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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INTRODUCTION
Geotechnical Engineering Report
City-maintained Roadways at Crowne at Old Town North
Lupine Drive
Southwest of Conifer Street and Blue Spruce Drive
Fort Collins, Colorado
Terracon Project No. 20185095 (revised)
Revised August 22, 2018
INTRODUCTION
This report presents the results of our subsurface exploration and geotechnical engineering
services performed for the Lupine Drive within the Crowne at Old Town North subdivision to be
located southwest of the intersection of Conifer Street and Blue Spruce Drive in Fort Collins,
Colorado. The purpose of these services is to provide information and geotechnical engineering
recommendations relative to:
■ Subsurface soil conditions ■ Site preparation and earthwork
■ Groundwater conditions ■ Pavement design and construction
The geotechnical engineering scope of services for this project included the advancement of two
(2) test borings to a depth of approximately 10 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 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 southwest of the intersection of Conifer Street and
Blue Spruce Drive in Fort Collins, Colorado. The project includes Lupine
Drive, which is a city-maintained roadway within the proposed subdivision.
The approximate Latitude/Longitude of the center of the site is 40.60156°
N/105.07313°W (Please refer to Site Location).
Geotechnical Engineering Report
City-maintained Roadways at Crowne at Old Town North ■ Fort Collins, Colorado
Revised August 22, 2018 ■ Terracon Project No. 20185095 (revised)
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Item Description
Existing
Improvements
We understand the site was originally a vacant field and is currently under
construction for the proposed subdivision.
Surrounding
Developments
The site is bordered by retail and commercial buildings to the north and west.
To the south and east of the site is undeveloped land followed by single-family
residential developments.
Current Ground
Cover
The site is currently covered with graded native soils and properly placed fills
in preparation for the construction of the proposed roadways.
Existing Topography The site is relatively flat and has been graded for proposed roadways.
PROJECT DESCRIPTION
Our initial understanding of the project was provided in our proposal and was discussed in the
project planning stage. A period of collaboration has transpired since the project was initiated,
and our final understanding of the project conditions is as follows:
Item Description
Information Provided
The following project information is based on conversation with the Connell
Resources, Inc. who is currently completing the earthwork for the project.
Project Description
We understand the new pavements are being constructed as part of the
project. Based on site plans, we understand two main city-maintained
roads will run through the proposed apartment structures. Lupine Drive
spans east-west roughly through the center of the development.
Grading/Slopes We understand the roadway is currently at finished grade.
Pavements
Traffic loads were provided to us by the City of Fort Collins. The following
traffic conditions were used for the design of Lupine Drive Pavements:
■ Lupine Drive west of Jerome Street: commercial local, 18-kip
equivalent single-axle load (ESAL) of 365,000
■ Lupine Drive east of Jerome Street: connector local, 18-kip
equivalent single-axle load (ESAL) of 73,000
GEOTECHNICAL CHARACTERIZATION
Subsurface Profile
Specific conditions encountered at each boring location are indicated on the individual boring logs.
Stratification boundaries on the boring logs represent the approximate location of changes in soil
types; in situ, the transition between materials may be gradual. Details for each of the borings can
be found in Exploration Results. A discussion of field sampling and laboratory testing procedures
Geotechnical Engineering Report
City-maintained Roadways at Crowne at Old Town North ■ Fort Collins, Colorado
Revised August 22, 2018 ■ Terracon Project No. 20185095 (revised)
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and test results are presented in Exploration and Testing Procedures. Based on the results of
the borings, subsurface conditions on the project site can be generalized as follows:
Material Description
Approximate Depth to Bottom of
Stratum
Density
Fill consisting of sandy lean clay
About 4 to 5 feet below existing
site grades.
--
Well graded sand and gravel with
varying amounts of silt and clay
To the maximum depth of
exploration of about 10 feet.
Loose to medium dense
Groundwater Conditions
The boreholes were observed while drilling and after completion for the presence and level of
groundwater. Groundwater was not observed in remaining borings while drilling, or for the short
duration the borings could remain open. These observations represent groundwater conditions at
the time of 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, amount of rainfall, runoff and
other factors not evident at the time the borings were performed. Therefore, groundwater levels
during construction or at other times in the life of the pavements may be higher or lower than the
levels indicated on the boring logs. However, we do not anticipate groundwater will significantly
impact the proposed construction.
Laboratory Testing
Representative soil samples were selected for swell-consolidation testing and exhibited no
movement to 2.1 percent swell when wetted. Samples of site soils 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.
CORROSIVITY
Results of water-soluble sulfate testing indicate Exposure Class S2 according to ACI 318. ASTM
V, or modified Type II portland cement should be specified for all project concrete on and below
grade. As an alternative, ACI allows the use of cement that conforms to ASTM C150 Type II
requirements, if it meets the Type V performance requirements (ASTM C452) of ASTM C150
Table 4. ACI 201 also allows a blend of any type of portland cement and fly ash with an expansion
Geotechnical Engineering Report
City-maintained Roadways at Crowne at Old Town North ■ Fort Collins, Colorado
Revised August 22, 2018 ■ Terracon Project No. 20185095 (revised)
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of less than 0.05 percent at 6 months when tested in accordance with ASTM C1012. Foundation
concrete should be designed for severe sulfate exposure in accordance with the provisions of the
ACI Design Manual, Section 318, Chapter 4.
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 expansive soils as a possible geotechnical conditions that could impact design,
construction and performance of the proposed pavements. This condition will require particular
attention in project planning, design and during construction and are discussed in greater detail
in the following sections.
Expansive Soils
Expansive soils are present on this site and 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 pavements
is possible. 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, such as treating the subgrade soils with fly ash. 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.
The General Comments section provides an understanding of the report limitations.
EARTHWORK
The following presents recommendations for subgrade preparation, fly ash treatment (if used)
and placement of aggregate base course on the project. All earthwork on the project should be
observed and evaluated by Terracon on a full-time basis. The evaluation of earthwork should
include observation of scarifications, moisture conditioning and compaction of subgrade soils for
swell mitigation; fly ash treatment, testing of aggregate base course, subgrade stabilization, and
other geotechnical conditions exposed during the construction of the project.
Geotechnical Engineering Report
City-maintained Roadways at Crowne at Old Town North ■ Fort Collins, Colorado
Revised August 22, 2018 ■ Terracon Project No. 20185095 (revised)
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Swell Mitigation and Subgrade Stabilization
Results of swell testing indicated swell mitigation is necessary at this site. We believe swell-
mitigation could be completed by scarifying, properly moisture conditioning and compacting the
top 12 inches of finished pavement subgrade prior to placement of aggregate base course and
asphalt materials. Even with properly prepared and compacted soils, the possibility of damage
to the pavements, such as uneven areas and cracking is possible. As an alternative, we believe
fly ash could be used to treat the upper 12 inches of the on-site soil for swell-mitigation.
The sulfate concentrations in the on-site soils are above typical acceptable limits to allow for
conventional chemical stabilization of subgrade soils. If fly ash is used stabilize subgrade below
the proposed pavements planned as part of this project, we recommend an initial application of
lime, followed by a 5 to 7 days mellowing period. After mellowing, the subgrade soils can be
treated with fly ash.
Lime and Fly Ash Treatment Recommendations
In order to reduce the risk of heave caused by adverse reaction between the sulfates in the
subgrade soils and the stabilization agent, we recommend chemical stabilization be performed
using double treatment application with lime and fly ash. We recommend the following general
procedures for construction of chemically treated pavement subgrade soils for the city-maintained
roadways on the project site.
The pavement subgrade should be shaped to final grade. We recommend initially treating the
upper 12 inches of the pavement subgrade uniformly with 3 percent lime by weight. The lime
should meet the requirements of ASTM C207, Type N and be mixed as outlined in ASTM C977.
Water should be added (as needed) to the lime-soil mixture during the mixing process until a
uniform, homogeneous mixture is achieved at or slightly above optimum moisture content for the
mixture. Following initial mixing with the lime, we recommend allowing the lime-soil mixture to
mellow for a period of 5 to 7 days. The mellowing time needed for the initial stabilization process
will depend on weather conditions, continuous moistening of the lime-soil mixture, protection
measures to promote ettringite formation, and soil properties. Terracon will assist the project
team with determining the appropriate mellowing time as the process approaches 5 days.
Following the mellowing period, we recommend thoroughly remixing the lime-soil mixture to
mechanically break down any ettringite formation that has occurred. An additional 8 percent fly
ash should then be remixed uniformly into the lime-soil mixture. Fly ash should meet the
requirements specified in ASTM C618 for Class C fly ash. The fly ash-lime-soil mixture should
be moisture conditioned to within 2 percent of optimum moisture content and compacted to at
least 95 percent of the mixture’s maximum dry unit weight as determined by ASTM D698.
Compaction of the mixture should be completed within 2 hours of the addition of water to the fly
Geotechnical Engineering Report
City-maintained Roadways at Crowne at Old Town North ■ Fort Collins, Colorado
Revised August 22, 2018 ■ Terracon Project No. 20185095 (revised)
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ash-lime-soil mixture. The subgrade should be compacted and sealed with a pneumatic-tire roller
that is sufficiently light in weight so as to not cause hairline cracking of the treated subgrade.
After completion of the double application and compaction, the treated subgrade should be
allowed to cure for a minimum of 48 hours prior to placing aggregate base course. A longer cure
time may be necessary depending on adverse weather conditions and protection measures
implemented by the contractor. During this cure time, the surface of the treated subgrade should
be kept moist by periodically sprinkling with water.
Strength gains of the treated subgrade will be slower during cooler weather periods, particularly
if the temperature drops below 40 degrees Fahrenheit. Construction traffic on the treated
subgrade prior to placement of the aggregate base course and pavement construction should be
limited and the subgrade should be protected from freezing or drying at all times until paving.
Covering the subgrade or other protective measures may be required.
Once trimming and the final subgrade elevation has been reached, the treated subgrade should
be proof-rolled with a rubber tire vehicle with at least 18 kips per axle. Areas of the treated
subgrade that are soft, excessively wet, or unstable should be repaired by drying and/or removal
and replacement. Chemically treated soils can be re-used as backfill for repaired areas.
Compaction Requirements
Moisture conditioned subgrade soils, fly ash treated subgrade (if used) and aggregate base course
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
Geotechnical Engineering Report
City-maintained Roadways at Crowne at Old Town North ■ Fort Collins, Colorado
Revised August 22, 2018 ■ Terracon Project No. 20185095 (revised)
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Item Description
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 proofrolled.
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.
Grading and Drainage
All grades must be adjusted to provide effective drainage away from the proposed pavements
during construction and maintained throughout the life of the proposed project. Infiltration of water
into excavations must be prevented during construction. Water permitted to pond near or
adjacent to the perimeter of the pavements (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.
Backfill against curbs and gutters should be properly compacted and free of all construction debris
to reduce the possibility of moisture infiltration. After construction of the proposed pavements and
prior to project completion, we recommend verification of final grading be performed to document
positive drainage, as described above, has been achieved
The General Comments section provides an understanding of the report limitations.
PAVEMENTS
Pavements - Subgrade Preparation
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 proofrolled with
a loaded tandem-axle dump truck prior to final grading and paving. Areas of soft spots should be
stabilized with removal, moisture conditioning and recompaction. All pavement areas should be
moisture conditioned and properly compacted to the recommendations in this report immediately
prior to paving.
Samples of the fill material selected for swell-consolidation testing swelled approximately no
movement to 2.1 percent when wetted under an applied pressure of 150 psf which is more than the
Geotechnical Engineering Report
City-maintained Roadways at Crowne at Old Town North ■ Fort Collins, Colorado
Revised August 22, 2018 ■ Terracon Project No. 20185095 (revised)
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maximum 2 percent criteria established for determining if swell-mitigation procedures in the
pavement sections are required per LCUASS standards. Therefore, swell-mitigation of the
subgrade materials prior to pavement operations is required. We believe scarifying, moisture
conditioning and properly compacting the upper 12 inches of on-site soils immediately prior to
placement of pavement materials will help mitigate possible swell potential of on-site soils. As a
lower risk alternative, fly ash treatment can be used, provided the subgrade soils are first treated
with lime in order to reduce the risk of heave caused by adverse reaction between the sulfates in
the subgrade soils and the stabilization agent. Recommendations for lime and fly ash treatment
are provided in the Earthwork section of this report.
Pavements – Design Recommendations
Design of pavements for the project have been based on the procedures outlined in the 1993
Guideline for Design of Pavement Structures prepared by the American Association of State
Highway and Transportation Officials (AASHTO) and the Larimer County Urban Area Street
Standards (LCUASS).
Traffic patterns and anticipated loading conditions were provided to us by the City of Fort Collins.
For our pavement thicknesses design recommendations, we used an 18-kip equivalent single-
axle load (ESAL) of 365,000 for Lupine Drive west of Jerome Street and 73,000 for Lupine Drive
east of Jerome Street. This assumed traffic design values should be verified by the civil engineer
or owner prior to final design and construction. If the actual traffic values vary from the assumed
values, the pavement thickness recommendations may not be applicable. When the actual traffic
design information is available Terracon should be contacted so that the design recommendations
can be reviewed and revised if necessary.
For flexible pavement design, a terminal serviceability index of 2.0 was utilized along with an inherent
reliability of 85 percent and a design life of 20 years. Using the calculated design R-value of 9,
appropriate ESAL, environmental criteria and other factors, the structural numbers (SN) of the
pavement sections were determined on the basis of the 1993 AASHTO design equation.
In addition to the flexible pavement design analyses, a rigid pavement design analysis was
completed based upon AASHTO design procedures. Rigid pavement design is based on an
evaluation of the Modulus of Subgrade Reaction of the soils (k-value), the Modulus of Rupture of
the concrete, and other factors previously outlined. The design k-value of 80 for the subgrade
soil was determined by correlation to the laboratory test results. A modulus of rupture of 600 psi
(working stress 450 psi) was used for pavement concrete. The rigid pavement thickness for each
traffic category was determined on the basis of the AASHTO design equation.
Recommended minimum pavement sections are provided in the table below.
Geotechnical Engineering Report
City-maintained Roadways at Crowne at Old Town North ■ Fort Collins, Colorado
Revised August 22, 2018 ■ Terracon Project No. 20185095 (revised)
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Roadway Alternative
Recommended Pavement Thicknesses (Inches)
Asphaltic
Concrete
Surface
Aggregate
Base
Course
Lime and Fly
Ash Treated
Subgrade
Portland
Cement
Concrete
Total
Lupine
Drive west
of Jerome
Street
A 5½ 10 - - 15½
B 4 8 12 - 24
C - - - 6½ 6½
Lupine
Drive east
of Jerome
Street
A 5 8 - - 13
B 4 6 12 - 22
C - - - 5 5
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 materials 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 dry unit weight as determined by ASTM
D698.
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 Superpave 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
Geotechnical Engineering Report
City-maintained Roadways at Crowne at Old Town North ■ Fort Collins, Colorado
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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. Joints should
be sealed to prevent entry of foreign material and doweled where necessary for load transfer.
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;
■ 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 features 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.
Geotechnical Engineering Report
City-maintained Roadways at Crowne at Old Town North ■ Fort Collins, Colorado
Revised August 22, 2018 ■ Terracon Project No. 20185095 (revised)
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GENERAL COMMENTS
As the project progresses, we address assumptions by incorporating information provided by the
design team, if any. Revised project information that reflects actual conditions important to our
services is reflected in the final report. The design team should collaborate with Terracon to
confirm these assumptions and to prepare the final design plans and specifications. This facilitates
the incorporation of our opinions related to implementation of our geotechnical recommendations.
Any information conveyed prior to the final report is for informational purposes only and should
not be considered or used for decision-making purposes.
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 effects of construction or weather.
The nature and extent of such variations may not become evident until during or after construction.
Terracon should be retained as the Geotechnical Engineer, where noted in the final 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.
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 provided 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.
ATTACH MENTS
ATTACHMENTS
SITE LOCA TION AND EXPLORATION PLANS
SITE LOCATION AND EXPLORATION PLANS
SITE LOCATION
City-Maintained Roadways at Crowne at Old Town North ■ Fort Collins, CO
Revised August 22, 2018 ■ Terracon Project No. 20185095 (revised)
TOPOGRAPHIC MAP IMAGE COURTESY OF THE U.S. GEOLOGICAL SURVEY
QUADRANGLES INCLUDE: WELLINGTON, CO (1978) and FORT COLLINS, CO (1984).
DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS
NOT INTENDED FOR CONSTRUCTION PURPOSES
SITE
EXPLORATION PLAN
City-Maintained Roadways at Crowne at Old Town North ■ Fort Collins, CO
Revised August 22, 2018 ■ Terracon Project No. 20185095 (revised)
DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS
NOT INTENDED FOR CONSTRUCTION PURPOSES
AERIAL PHOTOGRAPHY PROVIDED
BY MICROSOFT BING MAPS
EXPLORATION RESULTS
EXPLORATION RESULTS
Geotechnical Engineering Report
City-maintained Roadways at Crowne at Old Town North ■ Fort Collins, Colorado
Revised August 22, 2018 ■ Terracon Project No. 20185095 (revised)
Responsive ■ Resourceful ■ Reliable
EXPLORATION AND TESTING PROCEDURES
Field Exploration
The field exploration program consisted of the following:
Number of Borings Planned Boring Depth (feet)
1
Planned Location
2 10 or auger refusal
Approximately every 500 feet along
Lupine Drive
1. Proposed borings will be completed to the planned depths below existing site grades or practical
auger refusal, if shallower.
Boring Layout and Elevations: We used handheld GPS equipment to locate borings with an
estimated horizontal accuracy of +/-20 feet. We understand the ground surface elevation at the
time we completed our borings was at the finished grade of the planned Lupine Drive.
Subsurface Exploration Procedures: We advanced soil borings with a truck-mounted drill rig
using 4-inch solid-stem continuous-flight augers. Three samples were obtained in the upper 10
feet of each boring. 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. In addition, a bulk sample of soils obtained in the upper 5 feet of both borings
completed for the proposed roadways was collected. The samples were 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.
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 include
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 include modifications based on observations and
laboratory test results.
Geotechnical Engineering Report
City-maintained Roadways at Crowne at Old Town North ■ Fort Collins, Colorado
Revised August 22, 2018 ■ Terracon Project No. 20185095 (revised)
Responsive ■ Resourceful ■ Reliable
Property Disturbance: We backfilled borings with auger cuttings after completion. Our services
did not include repair of the site beyond backfilling our boreholes. 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, or grout the boreholes for additional fees, at your request.
Laboratory Testing
The project engineer reviewed field data and assigned various laboratory tests to better
understand the engineering properties of various soil strata. Laboratory testing was conducted in
general accordance with applicable or other locally recognized standards. 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 ■ R-value
Our laboratory testing program included examination 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.
54
11
14
14
5
118
26-17-9
NP
2-4-5
N=9
8-31
9-13-16
N=29
0/150
4.0
10.5
FILL - SANDY LEAN CLAY (CL), brown to light brown
WELL GRADED GRAVEL WITH SILT AND SAND to WELL
GRADED SAND (GW-GM), brown, medium dense
Boring Terminated at 10.5 Feet
GRAPHIC LOG
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20185095 CITY-MAINTAINED R.GPJ TERRACON_DATATEMPLATE.GDT 8/15/18
PERCENT FINES
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
LL-PL-PI
ATTERBERG
LIMITS
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
SAMPLE TYPE
FIELD TEST
RESULTS
SWELL / LOAD
(%/psf)
DEPTH
LOCATION See Exploration Plan
Latitude: 40.6015° Longitude: -105.0729°
Page 1 of 1
Advancement Method:
4-inch solid-stem auger
Abandonment Method:
Boring backfilled with soil cuttings upon completion.
1901 Sharp Point Dr, Ste C
Fort Collins, CO
Notes:
Project No.: 20185095
Drill Rig: CME-55
BORING LOG NO. 1
CLIENT: Crowne Partners, Inc.
Birmingham, AL
Driller: Drilling Engineers, Inc.
Boring Completed: 08-03-2018
PROJECT: City-Maintained Roadways at Crowne at
42
12
14
8
113
32-17-15
6-7
4-5-7
N=12
2-1
+2.1/150
5.0
10.0
FILL - SANDY LEAN CLAY , brown to light brown
CLAYEY GRAVEL WITH SAND to WELL GRADED SAND WITH
VARYING AMOUNTS OF SILT, CLAY AND GRAVEL (GC), brown,
medium dense
very loose
Boring Terminated at 10 Feet
GRAPHIC LOG
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20185095 CITY-MAINTAINED R.GPJ TERRACON_DATATEMPLATE.GDT 8/15/18
PERCENT FINES
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
LL-PL-PI
ATTERBERG
LIMITS
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
SAMPLE TYPE
FIELD TEST
RESULTS
SWELL / LOAD
(%/psf)
DEPTH
LOCATION See Exploration Plan
Latitude: 40.6015° Longitude: -105.0745°
Page 1 of 1
Advancement Method:
4-inch solid-stem auger
Abandonment Method:
Boring backfilled with soil cuttings upon completion.
1901 Sharp Point Dr, Ste C
Fort Collins, CO
Notes:
Project No.: 20185095
Drill Rig: CME-55
BORING LOG NO. 2
CLIENT: Crowne Partners, Inc.
Birmingham, AL
Driller: Drilling Engineers, Inc.
Boring Completed: 08-03-2018
PROJECT: City-Maintained Roadways at Crowne at
Old Town North
0
10
20
30
40
50
60
0 20 40 60 80 100
CL or OL CH or OH
ML or OL
MH or OH
"U" Line
"A" Line
ATTERBERG LIMITS RESULTS
ASTM D4318
P
L
A
S
T
I
C
I
T
Y
I
N
D
E
X
LIQUID LIMIT
PROJECT NUMBER: 20185095
SITE: Southwest of Conifer Street and Blue
Spruce Drive
Fort Collins, Colorado
PROJECT: City-Maintained Roadways at Crowne
at Old Town North
CLIENT: Crowne Partners, Inc.
Birmingham, AL
1901 Sharp Point Dr, Ste C
Fort Collins, CO
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. ATTERBERG LIMITS 20185095 CITY-MAINTAINED R.GPJ TERRACON_DATATEMPLATE.GDT 8/13/18
26
NP
32
17
NP
17
9
NP
15
54
11
42
CL
GW-GM
GC
SANDY LEAN CLAY
WELL-GRADED GRAVEL with SILT and SAND
CLAYEY GRAVEL
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
100 10 1 0.1 0.01 0.001
30
40
50
1.5
6 200
8
10
4 14
1
3/4
1/2
60
GRAIN SIZE IN MILLIMETERS
PERCENT FINER BY WEIGHT
U.HYDROMETERS. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS
4
3/8
3 100
3 140
2
GRAIN SIZE DISTRIBUTION
ASTM D422 / ASTM C136
6
16
20
PROJECT NUMBER: 20185095
SITE: Southwest of Conifer Street and Blue
Spruce Drive
Fort Collins, Colorado
PROJECT: City-Maintained Roadways at Crowne
at Old Town North
CLIENT: Crowne Partners, Inc.
Birmingham, AL
1901 Sharp Point Dr, Ste C
Fort Collins, CO
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GRAIN SIZE: USCS-2 20185095 CITY-MAINTAINED R.GPJ TERRACON_DATATEMPLATE.GDT 8/13/18
SANDY LEAN CLAY (CL)
WELL-GRADED GRAVEL with SILT and SAND (GW-GM)
-10
-8
-6
-4
-2
0
2
4
100 1,000 10,000
AXIAL STRAIN, %
PRESSURE, psf
SWELL CONSOLIDATION TEST
ASTM D4546
NOTES: Sample exhibited no movement upon wetting under an applied pressure of 150 psf.
PROJECT NUMBER: 20185095
SITE: Southwest of Conifer Street and Blue
Spruce Drive
Fort Collins, Colorado
PROJECT: City-Maintained Roadways at Crowne
at Old Town North
CLIENT: Crowne Partners, Inc.
Birmingham, AL
1901 Sharp Point Dr, Ste C
Fort Collins, CO
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. TC_CONSOL_STRAIN-USCS 20185095 CITY-MAINTAINED R.GPJ TERRACON_DATATEMPLATE.GDT 8/14/18
1 4 - 5 ft WELL GRADED GRAVEL WITH SILT AND SAND 118 14
Specimen Identification Classification , pcf WC, %
-10
-8
-6
-4
-2
0
2
4
100 1,000 10,000
AXIAL STRAIN, %
PRESSURE, psf
SWELL CONSOLIDATION TEST
ASTM D4546
NOTES: Sample exhibited 2.1 percent swell upon wetting under an applied pressure of 150 psf.
PROJECT NUMBER: 20185095
SITE: Southwest of Conifer Street and Blue
Spruce Drive
Fort Collins, Colorado
PROJECT: City-Maintained Roadways at Crowne
at Old Town North
CLIENT: Crowne Partners, Inc.
Birmingham, AL
1901 Sharp Point Dr, Ste C
Fort Collins, CO
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. TC_CONSOL_STRAIN-USCS 20185095 CITY-MAINTAINED R.GPJ TERRACON_DATATEMPLATE.GDT 8/14/18
2 2 - 3 ft SANDY LEAN CLAY 113 12
Specimen Identification Classification , pcf WC, %
Project Number:
Service Date:
Report Date:
Task:
Client
Date Received:
B-2
2.0
2241
Analyzed By:
The tests were performed in general accordance with applicable ASTM, AASHTO, or DOT test methods. This report is exclusively for the use of the client
indicated above and shall not be reproduced except in full without the written consent of our company. Test results transmitted herein are only applicable to
the actual samples tested at the location(s) referenced and are not necessarily indicative of the properties of other apparently similar or identical materials.
20185095
Sample Submitted By: Terracon (20) 8/10/2018
Results of Corrosion Analysis
Chemist
08/14/18
Lab No.: 18-0994
Sample Number
Sample Location
Sample Depth (ft.)
08/15/18
750 Pilot Road, Suite F
Las Vegas, Nevada 89119
(702) 597-9393
Project
CHEMICAL LABORATORY TEST REPORT
Trisha Campo
Water Soluble Sulfate (SO4), ASTM C 1580
(mg/kg)
Crowne Partners, Inc. City Roadways at Crowne at Old Town North
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado 80525
(970) 484-0359 FAX (970) 484-0454
CLIENT: Crowne Partners, Inc DATE OF TEST: 08-Aug-18
PROJECT: City Maintained Roadways
LOCATION: B1 and B2 at 0'-5'
TERRACON NO. 20185095 CLASSIFICATION: SANDY LEAN CLAY
TEST SPECIMEN NO. 1 2 3
COMPACTION PRESSURE (PSI) 50 75 110
DENSITY (PCF) 106.0 109.8 112.2
MOISTURE CONTENT (%) 21.9 19.7 19.2
EXPANSION PRESSURE (PSI) -2.23 -0.09 -0.40
HORIZONTAL PRESSURE @ 160 PSI 146 140 133
SAMPLE HEIGHT (INCHES) 2.35 2.49 2.53
EXUDATION PRESSURE (PSI) 229.8 302.9 377.1
CORRECTED R-VALUE 5.3 9.5 14.1
UNCORRECTED R-VALUE 5.6 9.5 14.1
R-VALUE @ 300 PSI EXUDATION PRESSURE = 9
AASHTO T190
PRESSURE OF COMPACTED SOIL
RESISTANCE R-VALUE & EXPANSION
SAMPLE DATA TEST RESULTS
0
10
20
30
40
50
60
70
80
90
100
0 100 200 300 400 500 600 700 800
R-VALUE
EXUDATION PRESSURE - PSI
SUPPORTING INFORMA TION
SUPPORTING INFORMATION
City-Maintained Roadways at Crowne at Old Town North Fort Collins, Colorado
August 22, 2018 Terracon Project No. 20185095 (revised)
less than 0.25
0.50 to 1.00
> 4.00
Unconfined
Compressive Strength
Qu, (tsf)
0.25 to 0.50
1.00 to 2.00
2.00 to 4.00
Modified
California
Ring
Sampler
Standard
Penetration
Test
Trace
GENERAL NOTES
> 30
11 - 30
Low 1 - 10
Non-plastic
Plasticity Index
#4 to #200 sieve (4.75mm to 0.075mm
Boulders
Cobbles 12 in. to 3 in. (300mm to 75mm)
Gravel 3 in. to #4 sieve (75mm to 4.75 mm)
Sand
Silt or Clay Passing #200 sieve (0.075mm)
Particle Size
Water Level After
a Specified Period of Time
Water Level After a
Specified Period of Time
Water Initially
Encountered
Soil classification is based on the Unified Soil Classification System. Coarse Grained Soils have more than 50% of their dry
weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand. Fine Grained Soils have less
than 50% of their dry weight retained on a #200 sieve; they are principally described as clays if they are plastic, and silts if they
are slightly plastic or non-plastic. Major constituents may be added as modifiers and minor constituents may be added
according to the relative proportions based on grain size. In addition to gradation, coarse-grained soils are defined on the basis
of their in-place relative density and fine-grained soils on the basis of their consistency.
GRAIN SIZE TERMINOLOGY
RELATIVEFINES PROPORTIONS OF SAND AND GRAVEL RELATIVE PROPORTIONS OF
DESCRIPTIVE SOIL CLASSIFICATION
LOCATION AND ELEVATION NOTES
SAMPLING WATER LEVEL FIELD TESTS
N
(HP)
(T)
(DCP)
UC
(PID)
(OVA)
Standard Penetration Test
Resistance (Blows/Ft.)
Hand Penetrometer
Torvane
UNIFIED SOIL CLASSIFICATION SYSTEM
City-maintained Roadways at Crowne at Old Town North ■ Fort Collins, Colorado
Revised August 22, 2018 ■ Terracon Project No. 20185095 (revised)
UNIFIED SOIL C LASSIFICATION 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 1 Cc 3 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 1 Cc 3 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 =
10 60
2
30
D x D
(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.
Dynamic Cone Penetrometer
Unconfined Compressive
Strength
Photo-Ionization Detector
Organic Vapor Analyzer
Medium
Over 12 in. (300 mm) 0
>12
5-12
<5
Percent of
Dry Weight
Major Component of Sample Term
Modifier
With
Trace
Descriptive Term(s) of
other constituents
Modifier >30
<15
Percent of
Dry Weight
Descriptive Term(s) of
other constituents
With 15-29
High
PLASTICITY DESCRIPTION
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.
DESCRIPTION OF SYMBOLS AND ABBREVIATIONS
Unless otherwise noted, Latitude and Longitude are approximately determined using a hand-held GPS device. The accuracy of
such devices is variable. 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.
Descriptive Term
(Consistency)
0 - 6
CONSISTENCY OF FINE-GRAINED SOILS
Hard
Very Loose
Loose
Medium Dense
Dense
Very Dense
Descriptive Term
(Density)
Standard Penetration
or N-Value
Blows/Ft.
0 - 3
4 - 9 7 - 18
10 - 29 19 - 58
30 - 50 59 - 98
> 50 > 99 Very Stiff
Standard Penetration or
N-Value
Blows/Ft.
Ring Sampler
Blows/Ft.
Ring Sampler
Blows/Ft.
5 - 9
Stiff
Medium Stiff
Soft
Very Soft
(50% or more passing the No. 200 sieve.)
Consistency determined by laboratory shear strength testing, field visual-manual
procedures or standard penetration resistance
STRENGTH TERMS
RELATIVE DENSITY OF COARSE-GRAINED SOILS
(More than 50% retained on No. 200 sieve.)
Density determined by Standard Penetration Resistance
2 - 4
4 - 8
8 - 15
15 - 30
> 30
0 - 1
3 - 4
< 3
10 - 18
19 - 42
> 42
CLAYEY GRAVEL (GC)
0.131
14.659
7.716
25
37.5
25
26
NP
32
54.4
11.0
41.7
9.9
55.1
44.6
1.109
14
5
8
35.8
33.9
13.7
WC (%) LL
D30 D10 %Gravel %Fines %Clay
1
1
2
1.93
9
NP
15
17
NP
17
337.85
Boring ID Depth USCS Classification PL PI Cc Cu
D100 D60
2 - 3.5
9 - 10.5
9 - 10
Boring ID Depth %Sand %Silt
medium
1
1
2
coarse fine coarse fine
COBBLES
GRAVEL SAND
SILT OR CLAY
2 - 3.5
9 - 10.5
9 - 10
Boring ID Depth LL PL PI Fines USCS Description
1
1
2
2 - 3.5
9 - 10.5
9 - 10
CL-ML
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.
Southwest of Conifer St and Blue Spruce Dr
Fort Collins, Colorado
SITE:
Boring Started: 08-03-2018
No free water observed
WATER LEVEL OBSERVATIONS
Old Town North
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.
Southwest of Conifer ST and Blue Spruce Dr
Fort Collins, Colorado
SITE:
Boring Started: 08-03-2018
No free water observed
WATER LEVEL OBSERVATIONS
Jerome Street. Additional pavement section alternatives and discussion are presented
in the report.
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.