HomeMy WebLinkAboutLAKEVIEW ON THE RISE SUBDIVISION - Filed GR-GEOTECHNICAL REPORT/SOILS REPORT - 2021-01-06REPORT COVER PAGE
Geotechnical Engineering Report
__________________________________________________________________________
City-Maintained Roadways at Lakeview on the Rise
Fort Collins, Colorado
May 20, 2019
Terracon Project No. 20195031
Prepared for:
Signature Construction, LLC
Carmel, Indiana
Prepared by:
Terracon Consultants, Inc.
Fort Collins, Colorado
CITY OF FORT COLLINS
APPROVED
05/24/2019
*Swell mitigation required
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REPORT TOPICS
INTRODUCTION ............................................................................................................. 1
SITE CONDITIONS ......................................................................................................... 1
PROJECT DESCRIPTION .............................................................................................. 2
GEOTECHNICAL CHARACTERIZATION ...................................................................... 3
CORROSIVITY................................................................................................................ 4
GEOTECHNICAL OVERVIEW ....................................................................................... 4
EARTHWORK................................................................................................................. 5
GROUND IMPROVEMENT ............................................................................................. 6
PAVEMENTS .................................................................................................................. 9
GENERAL COMMENTS ............................................................................................... 12
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ATTACHMENTS
EXPLORATION AND TESTING PROCEDURES
PHOTOGRAPHY LOG
SITE LOCATION AND EXPLORATION PLANS
EXPLORATION RESULTS
SUPPORTING INFORMATION
Note: Refer to each individual Attachment for a listing of contents.
Geotechnical Engineering Report
City-Maintained Roadways at Lakeview on the Rise ■ Fort Collins, Colorado
May 20, 2019 ■ Terracon Project No. 20195031
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REPORT SUMMARY
Topic
1
Overview Statement
2
Project
Overview
A geotechnical exploration has been performed for the proposed city-maintained
roadways at the new Lakeview on the Rise Apartment project currently under
construction at 6740 South College Avenue in Fort Collins, Colorado. Four (4)
borings were performed to depths of approximately 8 to 10 feet below existing site
grades.
Subsurface
Conditions
Subsurface conditions encountered in our exploratory borings generally consisted of
about 8 to 10 feet of fill materials consisting of lean clay with varying amounts of sand.
Sandstone to claystone bedrock was encountered below the fill materials in some of
the borings completed at the site and 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 or.
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.
Geotechnical
Concerns
■ As previously noted, existing fill was encountered to depths up to about 9 feet in the
borings drilled at the site. Existing fill could exist at other locations on the site and
extend to greater depths. Terracon is concurrently provided construction materials
testing for this project. We have reviewed the compaction test records for fill placed
in the roadways and we believe the fill is suitable below the proposed pavements.
■ 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. 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.
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.
Ground
Improvements
Results of swell testing indicated swell mitigation is necessary at this site. However,
our experience with properly moisture conditioned and compacted lean clay fill
similar to what materials were encountered below the pavements planned at this site
indicates primarily low swell conditions. 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
Geotechnical Engineering Report
City-Maintained Roadways at Lakeview on the Rise ■ Fort Collins, Colorado
May 20, 2019 ■ Terracon Project No. 20195031
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Topic
1
Overview Statement
2
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 and pavement distress. 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 existing and
proposed pavements. Water should not be allowed to pond on pavements and
conservative irrigation practices should be followed to avoid wetting pavement
subgrade. Excessive wetting of subgrade can cause movement and distress to the
pavements.
Pavements
Recommended Pavement thicknesses for this project include 5½ inches of asphalt
over 6 inches of aggregate base course. Additional pavement section alternatives and
discussion are presented in the report.
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
City-Maintained Roadways at Lakeview on the Rise
6740 South College Avenue
Fort Collins, Colorado
Terracon Project No. 20195031
May 20, 2019
INTRODUCTION
This report presents the results of our subsurface exploration and geotechnical engineering
services performed for the proposed city-maintained roadways to be located at the Lakeview on
the Rise apartment complex at 6740 South College Avenue in Fort Collins, Colorado. The purpose
of these services is to provide information and geotechnical engineering recommendations
relative to:
■ Subsurface soil and rock conditions ■ Excavation considerations
■ Groundwater conditions ■ Pavement design and construction
■ Site preparation and earthwork
The geotechnical engineering scope of services for this project included the advancement of four
(4) test borings to depths ranging from approximately 8 to 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 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 at 6740 South College Avenue in Fort Collins,
Colorado. The approximate Latitude/Longitude of the center of the site is
40.49068° N/105.07565°W (Please refer to Site Location).
Existing
Improvements
We understand the site was originally a vacant field that appeared to be
mowed on a semi-regular basis with a single-story structure on the west side
of the site and an irrigation on the north side of the site. The site is being
developed and is currently under construction for the proposed subdivision.
Geotechnical Engineering Report
City-Maintained Roadways at Lakeview on the Rise ■ Fort Collins, Colorado
May 20, 2019 ■ Terracon Project No. 20195031
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Item Description
Surrounding
Developments
The site is bordered by North College Avenue to the west, followed by single-
family residences and commercial developments. To the north and east of
the site are single-family residences, vacant land and irrigated farmland. To
the south of the site is Robert Benson Lake.
Current Ground
Cover
The current ground surface is graded bare-ground.
Existing Topography
The project site originally had rolling hills, slopping gradually downward to the
south of the site. The site is relatively flat following grading operations.
Previous
Geotechnical Studies
Previously, Terracon prepared Geotechnical Engineering Reports (Project No.
20165101; report dated January 12, 2017) for the proposed development
currently under construction and the CDOT-maintained roadways (Project No.
20185024; report dated June 14, 2019, revised October 9, 2018). In addition,
Terracon is providing construction materials testing and inspection for the
construction (Project No. 20181040). Data from these previous studies was
considered during preparation of this report.
We also collected photographs at the time of our field exploration program. Representative photos
are provided in our Photography Log.
PROJECT DESCRIPTION
Our final understanding of the project conditions is as follows:
Item Description
Information Provided The following project information is based on conversation with the client.
Project Description
We understand new pavements are being constructed as part of the project.
Based on site plans, we understand three city-maintained roadways will be
included in the project.
Grading/Slopes
We understand buried utilities have been installed and site grades for the
proposed city0maintened roadways is very near proposed grades.
Pavements
Based on information provided by the client, we understand Debra Drive,
Larien Lane and Stony Brook Road are considered residential connectors
with an 18-kip equivalent single-axle load (ESAL) of 73,000.
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 Engineering Report
City-Maintained Roadways at Lakeview on the Rise ■ Fort Collins, Colorado
May 20, 2019 ■ Terracon Project No. 20195031
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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
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
Consistency/Hardness
Fill materials consisting of lean
clay with varying amounts of sand
to clayey sand
About 8 to 9 feet below
existing site grades.
Medium stiff to very stiff
Sandstone to claystone bedrock
To the maximum depths of
exploration of about 10 feet
below existing site grades.
Weathered to firm
Groundwater Conditions
The boreholes were observed while drilling and shortly after completion for the presence and level
of groundwater. Groundwater was not observed in the borings while drilling, or for the short duration
the borings could remain open.
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 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. The
possibility of groundwater level fluctuations should be considered when developing the design
and construction plans for the project. However, we do not anticipate groundwater will
significantly impact the proposed roadways.
Laboratory Testing
Representative soil samples were selected for swell-consolidation testing and exhibited 0.5 to 4.4
percent swell when wetted. Samples of site soils selected for plasticity testing exhibited moderate
plasticity with liquid limits ranging from 42 to 37 and plasticity indices ranging from 24 to 30.
Laboratory test results are presented in the Exploration Results section of this report.
Geotechnical Engineering Report
City-Maintained Roadways at Lakeview on the Rise ■ Fort Collins, Colorado
May 20, 2019 ■ Terracon Project No. 20195031
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CORROSIVITY
Results of water-soluble sulfate testing indicate Exposure Class S0 according to ACI 318. ASTM
Type I portland cement should be specified for all project concrete on and below grade. Concrete
that comes in contact with on-site soil should be designed for low 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
and bedrock. We have identified several geotechnical conditions that could impact design,
construction and performance of the proposed pavements. These included existing fill and
expansive soils. These conditions will require particular attention in project planning, design and
during construction and are discussed in greater detail in the following sections.
Existing Fill
As previously noted, existing fill was encountered to depths up to about 9 feet in the borings drilled
at the site. Existing fill could exist at other locations on the site and extend to greater depths.
Terracon is concurrently provided construction materials testing for this project. We have
reviewed the compaction records for fill placed in the roadways and we believe the fill is suitable
below the proposed pavements.
Expansive Soils and Bedrock
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. 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.
Geotechnical Engineering Report
City-Maintained Roadways at Lakeview on the Rise ■ Fort Collins, Colorado
May 20, 2019 ■ Terracon Project No. 20195031
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EARTHWORK
The following presents recommendations for site preparation, excavation, subgrade preparation,
fill materials, compaction requirements and grading and drainage. 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 additional fill, strip and remove any deleterious materials (if any) from the
proposed construction areas. Prior 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 roadways.
Excavation
It is anticipated that excavations (if any) for the proposed construction can be accomplished with
conventional earthmoving equipment.
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.
Subgrade Preparation
The top 12 inches of the exposed ground surface should 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 pavement is placed.
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 scarifying 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.
Geotechnical Engineering Report
City-Maintained Roadways at Lakeview on the Rise ■ Fort Collins, Colorado
May 20, 2019 ■ Terracon Project No. 20195031
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Compaction Requirements
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
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.
Grading and Drainage
Pavements will be subject to post-construction movement. Maximum grades practical should be
used for paving and flatwork to prevent areas where water can pond. In addition, allowances in
final grades should take into consideration post-construction movement of pavements, particularly
if such movement would be critical. Where paving abuts a structure, care should be taken that
joints are properly sealed and maintained to prevent the infiltration of surface water.
GROUND IMPROVEMENT
Swell-Mitigation and Subgrade Stabilization
Results of swell testing indicated swell mitigation is necessary at this site. However, our
experience with properly moisture conditioned and compacted lean clay fill similar to what
materials were encountered below the pavements planned at this site indicates primarily low swell
conditions. 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.
Our experience also suggests lean clay soils moisture conditioned to optimum moisture content
or slightly above optimum moisture content for swell mitigation can also result in subgrade
Geotechnical Engineering Report
City-Maintained Roadways at Lakeview on the Rise ■ Fort Collins, Colorado
May 20, 2019 ■ Terracon Project No. 20195031
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conditions that exhibit deflection upon proof rolling. As an alternative, we believe fly ash could be
used to treat the upper 12 inches of the on-site soil for swell mitigation.
Results of water-soluble sulfate testing indicate Exposure Class S0 according to ACI 318. If fly
ash is used as swell-mitigation below the proposed pavements, we believe conventional
application methods can be used and double application or initial treatment with lime will not be
required.
The following provides general fly ash construction guidelines, which should be followed in
conjunction with those presented in Chapter 22 of LCUASS Manual.
Fly Ash Placement
■ The upper 12 inches of existing subgrade should be treated with 12 percent of Class C fly
ash. The fly ash shall consist of Class C fly ash meeting ASTM Specification C 618.
■ Water used in the stabilized mixture should be potable.
■ The machinery, equipment and tools necessary for proper placement of the fly ash and
soil mixture should be suitable for properly mixing and compacting the soil and fly ash
mixture.
■ It is important to prepare a completed course of treated material, which contains a uniform
fly ash soil mixture with no loose or segregated areas. The material should have a uniform
density and moisture content, is well bound its full depth and has a smooth surface suitable
for placing base course and pavement.
■ The subgrade should be graded and shaped to enable the fly ash treatment of materials
in place in conformance with lines, grades and thickness shown on the plans.
■ The fly ash shall be spread by a method approved by the engineer at the rate shown on
the plan or as directed by the engineer. Fly ash shall not be applied when wind conditions
in the opinion of the engineer are such that blowing fly ash becomes objectionable to traffic
or adjacent property owners.
■ During the final mixing, the material shall be moisture conditioned as directed by the
engineer until the proper moisture content has been obtained. However, initial mixing
after the addition to fly ash may be accomplished dry or with a minimum of water to prevent
fly ash balls.
Geotechnical Engineering Report
City-Maintained Roadways at Lakeview on the Rise ■ Fort Collins, Colorado
May 20, 2019 ■ Terracon Project No. 20195031
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■ Final moisture content of the mix prior to compaction shall not exceed the optimum
moisture content by more than 2 percent nor be less than the optimum moisture by more
than 2 percent during placement and compaction procedures.
■ The soil and fly ash shall be thoroughly mixed with approved road mixers or other
approved equipment and the mixing continued until in the opinion of the engineer a
homogeneous and friable mixture of soil and fly ash is obtained free from clods or lumps.
Water required to achieve the specific moisture content for the mixture should be added
after initial mixing. Compaction of the mixture shall begin immediately after mixing of the
fly ash and shall be completed within 2 hours following addition of water to the fly ash.
The material shall be sprinkled as necessary to maintain the optimum moisture.
Compaction of Fly Ash and Soil Mixture
■ Place and compact subgrade in horizontal lifts, using equipment and procedures that will
produce recommended moisture contents and densities throughout the lift as described
above.
■ Compaction of the mixture shall begin at the bottom and continue until the entire depth of
the mixture is uniformly and compacted to the specified density.
■ Uncompacted fill lifts should not exceed 12 inches loose thickness.
■ No fill should be placed over frozen ground.
■ The fly ash materials should be compacted to a minimum of 95 percent of maximum dry
density as determined by ASTM D698.
Curing
■ The final layer of treated subgrade should be thoroughly rolled with a pneumatic tire roller,
skimmed with a road grader to a depth of approximately 1/4-inch removing all loosened
stabilized material from the section. The moisture content of the surface material must be
maintained within the specified range during all finishing. Finishing shall proceed in such
a manner as to produce, in not more than 2 hours, a smooth, closely knit surface free of
cracks, ridges or loose material conforming to grades and plans.
■ After the fly ash treated course has been finished as specified, the surface shall be
protected against rapid drying by either of the following curing methods for a period of not
less than 3 days or until the surface of subsequent courses are in place.
o By maintaining a continuous moisture condition by sprinkling; or
Geotechnical Engineering Report
City-Maintained Roadways at Lakeview on the Rise ■ Fort Collins, Colorado
May 20, 2019 ■ Terracon Project No. 20195031
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o By applying an asphalt membrane to the treated course immediately after it is
completed. The type of asphalt used shall be sufficient to completely cover and seal
the total surface.
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 utility 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 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).
Samples of the on-site materials selected for swell-consolidation testing swelled approximately 0.5
to 4.4 percent when wetted under an applied pressure of 150 psf which is more than the maximum
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. Our experience with properly moisture conditioned and
compacted lean clay fill similar to what materials were encountered below the pavements planned
at this site indicates primarily low swell conditions. 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. Our experience also suggests lean clay soils
moisture conditioned to optimum moisture content or slightly above optimum moisture content for
swell mitigation can also result in subgrade conditions that exhibit deflection upon proof rolling.
As an alternative, we believe fly ash could be used to treat the upper 12 inches of the on-site soil
for swell mitigation. Construction recommendations for swell-mitigation alternatives of the
subgrade materials are provided in the Ground Improvements section of this report.
Geotechnical Engineering Report
City-Maintained Roadways at Lakeview on the Rise ■ Fort Collins, Colorado
May 20, 2019 ■ Terracon Project No. 20195031
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Based on information provided by the client, we understand Debra Drive, Larien Lane and Stony
Brook Road are considered residential connectors with an 18-kip equivalent single-axle load
(ESAL) of 73,000. These traffic design values should be verified by the City of Fort Collins 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 6,
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 74 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.
Alternative
Recommended Pavement Thicknesses (Inches)
Asphaltic
Concrete
Surface
Aggregate
Base
Course
Fly Ash
Treated
Subgrade
Portland
Cement
Concrete
Total
A 5½ 6 - - 11½
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
Geotechnical Engineering Report
City-Maintained Roadways at Lakeview on the Rise ■ Fort Collins, Colorado
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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
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.
For areas subject to concentrated and repetitive loading conditions 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;
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City-Maintained Roadways at Lakeview on the Rise ■ Fort Collins, Colorado
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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 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.
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 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 this 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.
Geotechnical Engineering Report
City-Maintained Roadways at Lakeview on the Rise ■ Fort Collins, Colorado
May 20, 2019 ■ Terracon Project No. 20195031
Responsive ■ Resourceful ■ Reliable 13
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.
Responsive ■ Resourceful ■ Reliable
ATTACHMENTS
Contents:
EXPLORATION AND TESTING PROCEDURES
PHOTOGRAPHY LOG
SITE LOCATION AND EXPLORATION PLANS
EXPLORATION RESULTS
SUPPORTING INFORMATION
Note: Refer to each individual Attachment for a listing of contents.
Geotechnical Engineering Report
City-Maintained Roadways at Lakeview on the Rise ■ Fort Collins, Colorado
May 20, 2019 ■ Terracon Project No. 20195031
Responsive ■ Resourceful ■ Reliable EXPLORATION AND TESTING PROCEDURES 1 of 2
EXPLORATION AND TESTING PROCEDURES
Field Exploration
The field exploration program consisted of the following:
Number of Borings Boring Depth (feet) Location
4 10 or auger refusal Planned roadways
Boring Layout and Elevations: We used handheld GPS equipment to locate borings with an
estimated horizontal accuracy of +/-20 feet. The ground surface at each boring location is
assumed to be at finished grade for the proposed roadways. We were not provided with a site
plan of the finished elevation grading at this time, we will revise boring logs with elevations when
the project team provides them.
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. Soil sampling was performed using modified California barrel and/or 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 encountered in the top 5 feet of the borings
performed will be 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. 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 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 Lakeview on the Rise ■ Fort Collins, Colorado
May 20, 2019 ■ Terracon Project No. 20195031
Responsive ■ Resourceful ■ Reliable EXPLORATION AND TESTING PROCEDURES 2 of 2
Property Disturbance: We backfilled borings with auger cuttings after completion. Our services
do 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 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 ■ R-value
Our laboratory testing program includes 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.
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.
Geotechnical Engineering Report
City-Maintained Roadways at Lakeview on the Rise ■ Fort Collins, Colorado
May 20, 2019 ■ Terracon Project No. 20195031
Responsive ■ Resourceful ■ Reliable PHOTOGRAPHY LOG 1 of 1
PHOTOGRAPHY LOG
Photo 1: Debra Drive (looking south)
Photo 2: Stony Brook Drive (looking east)
Responsive ■ Resourceful ■ Reliable
SITE LOCATION AND EXPLORATION PLANS
Contents:
Site Location Plan
Exploration Plan
Note: All attachments are one page unless noted above.
SITE LOCATION
City-Maintained Roadways at Lakeview on the Rise ■ Fort Collins, Colorado
May 20, 2019 ■ Terracon Project No. 20195031
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.
The line at the bottom about the general location is a separate table line. You can edit
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
City-Maintained Roadways at Lakeview on the Rise ■ Fort Collins, Colorado
May 20, 2019 ■ Terracon Project No. 20195031
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.
The line at the bottom about the general location is a separate table line. You can edit
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:
Boring Logs (B-1 through B-4)
Atterberg Limits
Grain Size Distribution
Consolidation/Swell (2 pages)
Note: All attachments are one page unless noted above.
8.0
4-5
3-5
4-6
21 74
22
22
103
105
104
42-14-28
FILL - LEAN CLAY WITH SAND to SANDY LEAN CLAY (CL), trace
gravel, light brown with tan, medium stiff to stiff
Boring Terminated at 8 Feet
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 20195031 CITY-MAINTAINED R.GPJ MODELLAYER.GPJ 4/29/19
DEPTH
Page 1 of 1
Advancement Method:
4-inch solid-stem augers
Abandonment Method:
Boring backfilled with auger cuttings upon completion.
1901 Sharp Point Dr, Ste C
Fort Collins, CO
Notes:
Project No.: 20195031
Drill Rig: CME-55
BORING LOG NO. 1
CLIENT: Signature Construction LLC
Carmel, IN
Driller: Drilling Engineers, Inc.
Boring Completed: 04-19-2019
PROJECT: City-maintained Roadways at Lakeview on
the Rise
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.
6740 South College Avenue
Fort Collins, CO
SITE:
Boring Started: 04-19-2019
No free water observed
WATER LEVEL OBSERVATIONS
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
FIELD TEST
RESULTS
SWELL / LOAD
(%/psf)
PERCENT FINES
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
9.0
10.5
6-15
11-18
15-22-37
N=59
+4.4/150
85
12
12
16
108
101 43-13-30
FILL - LEAN CLAY to SANDY LEAN CLAY (CL), trace gravel, light
brown with tan/white and gray, stiff to very stiff
SANDSTONE to CLAYSTONE, light brown to brown with orange and
gray, weathered to firm
Boring Terminated at 10.5 Feet
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 20195031 CITY-MAINTAINED R.GPJ MODELLAYER.GPJ 4/29/19
DEPTH
Page 1 of 1
Advancement Method:
4-inch solid-stem augers
Abandonment Method:
Boring backfilled with auger cuttings upon completion.
1901 Sharp Point Dr, Ste C
Fort Collins, CO
Notes:
Project No.: 20195031
Drill Rig: CME-55
BORING LOG NO. 2
CLIENT: Signature Construction LLC
Carmel, IN
Driller: Drilling Engineers, Inc.
Boring Completed: 04-19-2019
PROJECT: City-maintained Roadways at Lakeview on
the Rise
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.
6740 South College Avenue
Fort Collins, CO
SITE:
Boring Started: 04-19-2019
No free water observed
WATER LEVEL OBSERVATIONS
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
FIELD TEST
RESULTS
SWELL / LOAD
(%/psf)
PERCENT FINES
WATER
8.0
2-3
4-2-2
N=4
4-6
+0.5/150
61
14
11
22
104
103
37-13-24
FILL - SANDY LEAN CLAY to LEAN CLAY WITH SAND (CL), trace
gravel, light brown with orange/red brown, tan and gray, medium stiff to
stiff
Boring Terminated at 8 Feet
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 20195031 CITY-MAINTAINED R.GPJ MODELLAYER.GPJ 4/29/19
DEPTH
Page 1 of 1
Advancement Method:
4-inch solid-stem augers
Abandonment Method:
Boring backfilled with auger cuttings upon completion.
1901 Sharp Point Dr, Ste C
Fort Collins, CO
Notes:
Project No.: 20195031
Drill Rig: CME-55
BORING LOG NO. 3
CLIENT: Signature Construction LLC
Carmel, IN
Driller: Drilling Engineers, Inc.
Boring Completed: 04-19-2019
PROJECT: City-maintained Roadways at Lakeview on
the Rise
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.
6740 South College Avenue
Fort Collins, CO
SITE:
Boring Started: 04-19-2019
No free water observed
WATER LEVEL OBSERVATIONS
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
FIELD TEST
RESULTS
SWELL / LOAD
(%/psf)
PERCENT FINES
WATER
CONTENT (%)
DRY UNIT
8.0
10.5
10-12
9-12
6-12-19
N=31
8 72
11
20
102
37-13-24
FILL - LEAN CLAY WITH SAND to CLAYEY SAND (CL), trace
gravel, light brown with tan/white, stiff to very stiff
SANDSTONE to CLAYSTONE, light brown to brown with orange and
gray, weathered to firm
Boring Terminated at 10.5 Feet
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 20195031 CITY-MAINTAINED R.GPJ MODELLAYER.GPJ 4/29/19
DEPTH
Page 1 of 1
Advancement Method:
4-inch solid-stem augers
Abandonment Method:
Boring backfilled with auger cuttings upon completion.
1901 Sharp Point Dr, Ste C
Fort Collins, CO
Notes:
Project No.: 20195031
Drill Rig: CME-55
BORING LOG NO. 4
CLIENT: Signature Construction LLC
Carmel, IN
Driller: Drilling Engineers, Inc.
Boring Completed: 04-19-2019
PROJECT: City-maintained Roadways at Lakeview on
the Rise
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.
6740 South College Avenue
Fort Collins, CO
SITE:
Boring Started: 04-19-2019
No free water observed
WATER LEVEL OBSERVATIONS
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
FIELD TEST
RESULTS
SWELL / LOAD
(%/psf)
PERCENT FINES
WATER
CONTENT (%)
DRY UNIT
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: 20195031
SITE: 6740 South College Avenue
Fort Collins, CO
PROJECT: City-maintained Roadways at
Lakeview on the Rise
CLIENT: Signature Construction LLC
Carmel, IN
1901 Sharp Point Dr, Ste C
Fort Collins, CO
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. ATTERBERG LIMITS 20195031 CITY-MAINTAINED R.GPJ TERRACON_DATATEMPLATE.GDT 4/24/19
42
43
37
37
14
13
13
13
28
30
24
24
CL
CL
CL
CL
LEAN CLAY with SAND
LEAN CLAY
SANDY LEAN CLAY
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
1.5 50
6 8 200
4 10 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 3 100 140
2
GRAIN SIZE DISTRIBUTION
ASTM D422 / ASTM C136
6 16
20
PROJECT NUMBER: 20195031
SITE: 6740 South College Avenue
Fort Collins, CO
PROJECT: City-maintained Roadways at
Lakeview on the Rise
CLIENT: Signature Construction LLC
Carmel, IN
1901 Sharp Point Dr, Ste C
Fort Collins, CO
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GRAIN SIZE: USCS-2 20195031 CITY-MAINTAINED R.GPJ TERRACON_DATATEMPLATE.GDT 4/29/19
medium
1
2
3
4
coarse fine coarse fine
COBBLES GRAVEL SAND
SILT OR CLAY
LEAN CLAY with SAND (CL)
LEAN CLAY (CL)
SANDY LEAN CLAY (CL)
LEAN CLAY with SAND (CL)
-14
-12
-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 4.4 percent swell upon wetting under an applied pressure of 150 psf.
PROJECT NUMBER: 20195031
SITE: 6740 South College Avenue
Fort Collins, CO
PROJECT: City-maintained Roadways at
Lakeview on the Rise
CLIENT: Signature Construction LLC
Carmel, IN
1901 Sharp Point Dr, Ste C
Fort Collins, CO
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. TC_CONSOL_STRAIN-USCS 20195031 CITY-MAINTAINED R.GPJ TERRACON_DATATEMPLATE.GDT 4/29/19
2 2 - 3 ft LEAN CLAY 108 12
Specimen Identification Classification , pcf WC, %
-14
-12
-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 0.5 percent swell upon wetting under an applied pressure of 150 psf.
PROJECT NUMBER: 20195031
SITE: 6740 South College Avenue
Fort Collins, CO
PROJECT: City-maintained Roadways at
Lakeview on the Rise
CLIENT: Signature Construction LLC
Carmel, IN
1901 Sharp Point Dr, Ste C
Fort Collins, CO
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. TC_CONSOL_STRAIN-USCS 20195031 CITY-MAINTAINED R.GPJ TERRACON_DATATEMPLATE.GDT 4/29/19
3 2 - 3 ft SANDY LEAN CLAY 104 14
Specimen Identification Classification , pcf WC, %
##
Client:
Project:
Site:
Project No.:
R-Value Test
Signature Construction LLC
6740 South College Avenue
20195031
City-Maintained Roadways at Lakeview on the Rise
Bulk 91.7 113.8 15.3 6
Specimen Identification
Compaction Pressure
(psi) Dry Density (pcf) Moisture Content (%) R-Value at 300 psi
0
10
20
30
40
50
60
70
80
90
100
800 700 600 500 400 300 200 100
R-Value
Exudation Pressure, psi
Project Number:
Service Date:
Report Date:
Task:
Client
Date Received:
B-1 B-4
2.0 2.0
94 33
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.
20195031
Sample Submitted By: Terracon (20) 4/23/2019
Results of Corrosion Analysis
Chemist
04/25/19
Lab No.: 19-0460
Sample Number
Sample Location
Sample Depth (ft.)
05/02/19
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)
Signature Construction LLC City-Maintained Roadways at Lakeview on the Rise
SUPPORTING INFORMATION
Contents:
General Notes
Unified Soil Classification System
Description of Rock Properties
Note: All attachments are one page unless noted above.
City-maintained Roadways at Lakeview on the Rise Fort Collins, CO
May 20, 2019 Terracon Project No. 20195031
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
Trace
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
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)
UNIFIED SOIL CLASSIFICATION SYSTEM
UNIFIED SOIL 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:
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 Highway Administration, Publication No FHWA-NHI-10-034, December 2009
Technical Manual for Design and Construction of Road Tunnels – Civil Elements
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.
(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
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
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.
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.
Very Loose 0 - 3
STRENGTH TERMS
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
15 - 30 > 119
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
42
43
37
37
74.5
85.3
60.9
71.6
21
12
11
8
1
2
3
4
28
30
24
24
14
13
13
13
2 - 3
4 - 5
4 - 5.5
2 - 3
2 - 3
4 - 5
4 - 5.5
2 - 3
0.2
0.0
2.3
0.0
25.4
14.7
36.7
28.4
9.5
4.75
9.5
0.85
Boring ID Depth WC (%) LL PL PI Cc Cu
Boring ID Depth D100 D60 D30 D10 %Gravel %Sand %Silt %Fines %Clay
USCS Classification
%Cobbles
0.0
0.0
0.0
0.0
LEAN CLAY with SAND
Boring ID Depth LL PL PI Fines USCS Description
1
2
3
4
2 - 3
4 - 5
4 - 5.5
2 - 3
74
85
61
72
CL-ML
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
LOCATION See Exploration Plan
Latitude: 40.4899° Longitude: -105.0744°
GRAPHIC LOG
SAMPLE TYPE
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
LOCATION See Exploration Plan
Latitude: 40.4901° Longitude: -105.0759°
GRAPHIC LOG
SAMPLE TYPE
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
LOCATION See Exploration Plan
Latitude: 40.4912° Longitude: -105.0768°
GRAPHIC LOG
SAMPLE TYPE
LL-PL-PI
LOCATION See Exploration Plan
Latitude: 40.4915° Longitude: -105.0759°
GRAPHIC LOG
SAMPLE TYPE
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. Our experience also suggests lean clay soils moisture conditioned to
optimum moisture content or slightly above optimum moisture content for swell
mitigation can also result in subgrade conditions that exhibit deflection upon proof
rolling. As an alternative, we believe fly ash could be used to treat the upper 12
inches of the on-site soil for swell mitigation.