HomeMy WebLinkAboutReports - Soils - 10/22/2025
Report Cover Page
Prepared for:
Big D Oil Company
PO Box 1378
Rapid City, South Dakota 57702
Harmony Lakes – Public
Improvements
Geotechnical Engineering Report
Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials i
Table of Contents
Introduction .................................................................................................... 1
Project Description .......................................................................................... 1
Site Conditions ................................................................................................ 3
Geotechnical Characterization ......................................................................... 4
Subsurface Profile ..................................................................................... 4
Groundwater Conditions ............................................................................. 5
Seismic Site Class ............................................................................................ 6
Corrosivity ...................................................................................................... 7
Geotechnical Overview .................................................................................... 8
Existing, Undocumented Fill ........................................................................ 8
Shallow Groundwater ................................................................................ 9
Expansive/Compressible Soils and Bedrock ................................................... 9
Low Strength and Low Relative Density Soils ................................................. 9
Foundation Recommendations .................................................................... 10
Pavements .............................................................................................. 10
Earthwork ..................................................................................................... 11
Demolition .............................................................................................. 11
Site Preparation ....................................................................................... 11
Excavation .............................................................................................. 12
Subgrade Preparation ............................................................................... 13
Subgrade Stabilization .............................................................................. 14
Fill/Embankment Material Types ................................................................. 15
Fill/Embankment Placement and Compaction Requirements ............................ 16
Utility Trench Backfill ............................................................................... 17
Grading and Drainage ............................................................................... 18
Exterior Slab Design and Construction ......................................................... 19
Earthwork Construction Considerations ....................................................... 19
Construction Observation and Testing ......................................................... 20
Shallow Foundations ..................................................................................... 20
Reinforced Mats – Design Recommendations ................................................ 20
Shallow Foundation Construction Considerations ........................................... 23
Below-Grade Structures ................................................................................. 24
Lateral Earth Pressures ................................................................................. 24
Design Parameters ................................................................................... 24
Pavements .................................................................................................... 26
General Pavement Comments .................................................................... 26
Pavements – Subgrade Preparation ............................................................ 26
Pavements – Design Reccomendations ........................................................ 26
Full -Depth Composite Asphalt Pavement Section Thickness ............................ 27
Pavements – Construction Considerations .................................................... 28
Pavements – Maintenance ......................................................................... 29
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials ii
General Comments ........................................................................................ 29
Figures
GeoModel
Attachments
Exploration and Testing Procedures
Site Location and Exploration Plans
Exploration and Laboratory Test Results
Supporting Information
Note: This report was originally delivered in a web -based format. Blue Bold text in the
report indicates a referenced section heading. The PDF version also includes hyperlinks
which direct the reader to that section and clicking on the logo will bring you
back to this page. For more interactive features, please view your project online at
client.terracon.com .
Refer to each individual Attachment for a listing of contents.
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials 1
Introduction
This report presents the results of our subsurface exploration and Geotechnical
Engineering services performed for the proposed public roadway planned to extend the
W. Frontage Road south from the intersection with East Harmony Road and the proposed
lift station planned along the new roadway to be construction at the site with an address
of 4315 East Harmony Road in Fort Collins, Colorado . The purpose of these services was
to provide information and geotechnical engineering recommendations relative to:
■ Sub surface soil conditions
■ Groundwater conditions
■ Seismic site classification per IBC
■ Site preparation and earthwork
■ Demolition considerations
■ Dewatering considerations
■ Foundation design and construction for the lift station
■ Lateral earth pressures for the lift station
■ Pavement design and construction for the new public roadway
The geotechnical engineering Scope of Services for this project included the
advancement of test borings (designated as Boring Nos. B -1 through B -12), laboratory
testing, engineering analysis, and preparation of this report.
Drawings showing the site and boring locations are presented in the Site Location and
Exploration Plan section of this report . The results of the laboratory testing performed
on soil samples obtained from the site during our field exploration are included on the
boring logs and as separate graphs in the Exploration Results section.
A separate report utilizing the same project data was issued (see our Geotechnical
Engineering Report dated October 21, 2025 ; Terracon Project No. 20255045 ) to provide
geotechnical recommendations for the planned convenience store and fuel ing station
(see Boring Nos. B -1 through B -5 and B-7) within the Harmony Lakes development.
Project Description
Our initial understanding of the project was provided in our proposal and was discussed
during project planning. A period of collaboration has transpired since the project was
initiated, and our final understanding of the project conditions is as follows:
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials 2
Item Description
Information
Provided
The project information described below is based on the
following:
■ Communications with Kristin Turner at TB Group
■ Site plan provided by TB Group dated April 5th, 2024
■ Conceptual layout provided by Bulldog Engineering dated
March 7th, 2024
■ Communication with Andy Reese at Kimley-Horn and
Associates (KHA)
Project
Description
We understand the proposed project consists of the construction
of a public road to extend the W. Frontage Road south from the
intersection with East Harmony Road . The roadway alignment
will be west of the proposed Big D Oil convenience store and
fuel ing station. The roadway alignment is anticipated to be
about 750 to 900 feet in length. We understand the roadway will
be two lanes wide and likely have right and left turn lanes. We
assumed the new roadway is classified as a major collector.
Due to the requirements presented in Chapter 5.1.1 Section B of
LCUASS (Larimer County Urban Area Street Standards), two
separate soil exploration phases for the public roadway portion
of this project are required . This report entails the findings of
the initial exploration as described in Chapter 5.1.1 Section A
and Chapt er 5.2.1 Section A of LCUASS . The final, or second,
soil exploration for the public roadway will need to occur after
grading and utility installation is complete per LCUASS. A
separate report will be required for the final exploration upon
completion of the roadway. Terracon can provide this service
upon request.
A lift station is also planned as part of the Harmony Lakes
development. The dimensions of the lift station were unavailable
at the time of this report. Therefore, we have a ssumed the
structure wil l have dimensions of about 15 feet by 15 feet or
less. We understand the lift station will extend about 15 to 20
feet below existing grades. We have assumed it will be
constructed of reinforced concrete and be supported on a
reinforced concrete mat foundation system.
Grading/Slopes
Grading plans were not provided to Terracon at the time of this
proposal. We anticipate cuts and fills on the order of 5 feet or
less will be required to achieve proposed grades along the
roadway alignment . We also anticipate deeper cuts and fills
could be required for utility construction.
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials 3
Item Description
Below-Grade
Structures
The p roposed lift station is planned to extend about 15 to 20
feet below existing grades.
Pavements
New pavements for the proposed publi c roadway are planned as
part of this project and will likely consist of flexible asphalt
pavement.
Pavements for the new public roadway will be designed in
accordance with LCUASS requirements. Based on an assumed
roadway classification of a major collector , we have used an
Equivalent Daily Load Application (EDLA) value of 50 per
LCUASS to estimate anticipated traffic loads . A pavement design
period of 20 years was used in the pavement thickness analysis.
Terracon should be notified if any of the above information is inconsistent with the
planned construction as modifications to our recommendations may be necessary.
Site Conditions
The following description of site conditions is derived from our site visit in association
with the field exploration .
Item Description
Parcel
Information
The project site is located at 4315 East Harmony Road in Fort
Collins, Colorado.
Latitude/Longitude (approximate): 40.52232 ° N, 104.99631° W
(see Site Location ).
Existing
Improvements
Current improvements include greenhouse systems,
warehouses, office buildings, parking areas, and driveways. An
existing gas station is located on the north side of the property.
Based on historical aerial imagery from 2006, the eastern side
of the property appeared to consist of a pond. By 2009, the
northern portion of the pond appeared to be filled in . Sand
mining and regr ading has possibly taken place on the property.
Current Ground
Cover
Portions of the western areas of the property are aggregate
surfaced or paved with asphalt. The eastern side of the property
is mainly earthen fields with some vegetation and aggregate
surfaced driveways .
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials 4
Item Description
Existing
Topography
Based on publicly available USGS topographic maps and a site
plan provided by TB Group, ground surface elevations at the
project site slope from the northwest down towards the
southeast with a total change in elevation of about 10 feet
across the site.
Geotechnical Characterization
We have developed a general characterization of the subsurface conditions based upon
our review of the subsurface exploration, laboratory data, geologic setting , and our
understanding of the project. This characterization, termed GeoModel, forms the basis of
our geotechnical calculations and evaluation of the site. Conditions observed at each
exploration point are indicated on the individual logs. The individual l ogs can be found in
the Exploration Results and the GeoModel can be found in the Figures attachment of
this report.
Subsurface Profile
As part of our analyses, we identified the following model layers within the subsurface
profile. For a more detailed view of the model layer depths at each boring location, refer
to the GeoModel.
Model
Layer Layer Name General Description
1
Existing
Surfacing
Materials
About 3 to 19 inches of aggregate surfacing in Boring
Nos. B-1 to B-5, B-7 to B-9, B-11, and B-12. About
3.25 inches of asphalt in Boring No. B -6.
2 Existing Fill
Consisted primarily of clay soils with variable amounts
of sand and gravel or sand soils with variable amounts
of clay and gravel. Encountered in Boring Nos. B -1,
B-2, and B-4 to B-12.
3 Clay Soils Very soft to stiff clay soils with variable amounts of
sand and gravel.
4 Sand Soils Very loose to very dense sand soils with variable
amounts of fines and gravel.
5 Bedrock Medium hard to very hard claystone bedrock.
As noted in General Comments, this characterization is based upon widely spaced
exploration points across the site and variations are likely. Stratification boundaries on
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials 5
the boring logs represent the approximate location of changes in material types; in situ,
the transition between materials may be gradual.
Based on our experience in the area and the results of the laboratory testing, the on -site
clayey soils are considered to have low expansive potential or to be slightly
compressible. The claystone bedrock is considered to have low to moderate expansive
potential. Laboratory test results are presented in Exploration Results.
Groundwater Conditions
The boreholes were observed while drilling and shortly after completion for the presence
and level of groundwater. In addition, delayed water levels were also obtained in some
borings. The water levels observed in the boreholes are noted on the attached boring
logs and are summarized in the following table .
Boring
Number
Depth to
Groundwater
While Drilling,
ft.
Depth to
Groundwater
After Drilling,
ft.
Depth to
Groundwater
Approximately
24 Hours
After Drilling,
ft.
Approx.
Elevation of
Groundwater
After Drilling,
ft.1
B-1 14 9.9 Boring
backfilled ±4,837
B-2 14 8.6 Boring
backfilled ±4,839½
B-3 7 4.9 Boring
backfilled ±4,841
B-4 14 6.3 Boring
backfilled ±4,842½
B-5 7 10 7.3 ±4,839½
B-6 7 Not measured Boring
backfilled --
B-7 7 7.3 Boring
backfilled ±4,839½
B-8 7 Not measured Boring
backfilled --
B-9 9 3.2 Boring
backfilled ±4,840
B-10 Not encountered while drilling 2.2 ±4,840
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials 6
Boring
Number
Depth to
Groundwater
While Drilling,
ft.
Depth to
Groundwater
After Drilling,
ft.
Depth to
Groundwater
Approximately
24 Hours
After Drilling,
ft.
Approx.
Elevation of
Groundwater
After Drilling,
ft.1
B-11 14 9.0 Boring
backfilled ±4,839
B-12 7 9.5 3.7 ±4,841½
1. Elevation of groundwater is based on the ground surface elevations at the boring locations
interpolated from a topographic site plan provided by TB Group.
These observations represent relatively short -term groundwater conditions at the time of
and after completion of the field exploration and may not be indicative of other times or
at other locations. Long -term groundwater monitoring was outside the scope of services
for this project.
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
con struction or at other times in the life of the structure 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 p roject.
Seismic Site Class
The seismic design requirements for buildings and other structures are based on Seismic
Design Category. Site Classification is required to determine the Seismic Design
Category for a structure. The Site Classification is based on the upper 100 feet of the
site profile defined by a weighted average value of either shear wave velocity, standard
penetration resistance, or undrained shear strength in accordance with Section 20.4 of
ASCE 7 and the International Building Code (IBC). Based on the soil and bedrock
properties observed at the site as described on the exploration logs and laboratory test
results, our professional opinion is a Seismic Site Classification of D be considered for
the lift station portion of this project. Subsurface explorations at this site were extended
to a maximum depth of about 34½ feet. The site properties below the boring depth to
100 feet were estimated based on our experience and knowledge of geologic conditions
of the general area. Additional deeper borings or geophysical testi ng may be performed
to confirm the conditions below the current boring depth.
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials 7
Corrosivity
The table below lists the results of laboratory soluble sulfate, soluble chloride , sulfides,
electrical resistivity, RedOx , and pH testing. The values may be used to estimate
potential corrosive characteristics of the on -site soils with respect to contact with the
various underground materials which will be used for project construction.
Corrosivity Test Results Summary
Boring
(Sample
Depth)
Soluble
Sulfate
(%)
Soluble
Chloride
(%)
Sulfides
Total
Salts
(%)
Electrical
Resistivity
(Ω-cm)1
Redox
(mV) pH
B-1
(1-5 feet) 0.0405 - - - - - -
B-2
(1-5 feet ) 0.0102 0.0061 Nil 0.0935 1,500 234 8.47
B-4
(1-5 feet ) 0.0378 - - - - - -
B-8
(1-5 feet ) 0.0120 0.0016 Nil 0.0466 4,200 244 8.5
B-10
(1-5 feet ) 0.0228 - - - - - -
1. Laboratory electrical resistivity testing was performed on saturated soil samples.
Results of water-soluble sulfate testing indicate Exposure Class S0 according to ACI
(American Concrete Institute) 318. Therefore, ASTM Type I or II portland cement or
Type IL portland -limestone cement can be specified for all project concrete on and below
grade. Foundation concrete can be designed fo r low sulfate exposure in accordance with
the provisions of the ACI 318.
Numerous sources are available to characterize corrosion potential to buried metals
using the parameters above. ANSI/AWWA is commonly used for ductile iron, while
threshold values for evaluating the effect on steel can be specific to the buried feature
(e.g., piling, culverts, welded wire reinforcement, etc.) or agency for which the work is
performed. Imported fill materials may have significantly different properties than the
site materials noted above and should be evaluated if expected to be in contact w ith
metals used for construction. Consultation with a NACE certified corrosion professional is
recommended for buried metals on the site.
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials 8
Geotechnical Overview
Based on subsurface conditions encountered in the boring s, 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 /compressible soils and bedrock. We have identified several geotechnical
conditions that could impact design, construction , and performance of the proposed
pavements and lift station structure . These included existing, undocumented fill , shallow
groundwater, expansive/compressible soils and bedrock, and potentially soft, low
strength clay soils and loose, low relative density sand 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, Undocumented Fill
Existing, undocumented fill was encountered to depths up to about 7 feet in all borings
drilled at the site except Boring No. B-3. Existing fill could exist at other locations on the
site and extend to greater depths. We do not possess any information regarding whether
the fill was placed under the observation of a geotechnical engineer. Therefore, we
consider the fill as undocumented. Undocumented fill can present a greater than normal
risk of post -construction movement of foundations, on-grade slabs, pavements, and
other site improvements (if any) supported on or above these materials. Consequently,
existing fill within the project limits should not be relied up on for support of shallow
foundations, slabs, pavements , or other site improvements . A low risk alternative is
complete removal of existing fill down to native soil below foundations, slabs,
pavements, and other site improvements and replaced with moisture conditioned,
properly compacted engineered fill /embankment prior to new fill/embankment
placement and/or new construction.
If the owner is willing to accept greater than normal risk of movement below the
planned pavements, existing fill can be left in place below pavements. If the owner
elects to construct pavements on the existing fill to reduce initial construction costs , the
following protocol should be followed. At a minimum, we recommend the subgrade soils
below new pavements be scarified as discussed in the Subgrade Preparation section of
Earthwork prior to placing new engineered fill /embankment or constructing new
pavements. We also recommend thoroughly proof rolling the prepared subgrade prior to
placing aggregate base course and/or pavement materials . Areas exhibiting significant
deflection and/or pumping during the proof roll will need to be repaired prior to
pavement construction. Once the planned subgrade elevation has been reached, the
entire pavement area should be proof rolled. Areas of soft or o therwise unsuitable
material should be undercut and replaced with either new engineered fill /embankment or
suitable, existing on -site materials.
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials 9
Shallow Groundwater
As previously presented, groundwater was measured at depths ranging from about 2.2
to 14 feet below existing site grades . In general, measured groundwater levels were
shallowest on the eastern portion of the site in the vicinity of Boring Nos. B -3, B-9, and
B-10, and in Boring No. B -12. It is also possible and likely that groundwater levels below
this site may rise as water levels in neighboring bodies of water and/or the Cache la
Poudre River rise. We understand a below -grade lift station is planned on the west side
of the new roadway alignment. We anticipate the lift station will extend about 15 to 20
feet below existing grades. Terracon recommends maintaining a separation of at least 3
feet (or less if stable conditions at the subgrade bearing levels can be maintained during
construction) between the bottom of proposed below -grade foundations and measured
groundwater levels during construction and post-construction , if possible. The purpose of
this is to allow for construction “in the dry”. Where below-grade structures such as the
planned lift station extend below anticipated groundwater levels and permanent
dewatering is not planned, these below -grade structures will need to be designed as
water-tight and resistant to buoyant forces. Temporary construction dewatering and the
development of a sufficien t dewatering plan by a dewatering contractor may be needed.
Design and installation of a permanent subsur face drainage system may also be needed.
Expansive /Compressible Soils and Bedrock
Expansive/compressible soils and bedrock are present on this site; however, our
experience in the area and the laboratory test results indicate on -site soils are generally
low swelling or slightly compressible. The claystone bedrock is generally considered low
to moderately swelling. 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 structure, pavements, and flatwork is possible. The
severity of cracking and other damage such as uneven slabs and flatwork will probably
increase if modification of the site results in excessive wetting or drying of the
expansive/compressible soils and/or claystone bedrock . Eliminating the risk of
movement and cosmetic distress is generally not feasible . It is imperative that the
recommendations described in the Grading and Drainage section of Earthwork be
followed to reduce potential movement.
Low Strength and Low Relative Density Soils
Comparatively soft, low strength clay soils were encountered at a depth of about 7 feet
in Boring Nos. B-2, B-4, and B -9 and a depth of about 4 feet in Boring No. 10.
Comparatively loose, low relative density sand soils were encountered within the upper
approximately 4 feet of Boring Nos. B-5 and B-7 and at depths of about 7 to 14 feet of
Boring Nos. B-10 and B -11 completed at this site . These materials present a risk for
potential settlement of shallow foundations, on -grade slabs, pavements and other
surficial improvements. These materials can also be susceptible to disturbance and loss
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials 10
of strength under repeated construction traffic loads and unstable conditions could
develop. Stabilization of soft /loose soils may be required at some locations to provide
adequate support for construction equipment and proposed structures. Consequently,
Terracon recommends a contingency be provided in the construction budget to stabilize
and correct weak/unstable subgrade. Terracon should be contacted if these conditions
are encountered to observe the conditions exposed and to provide guidance regarding
stabilization (if needed).
Foundation Recommendations
Based on our communication with the design team, we understand the lift station
structure will extend below grade about 15 to 20 feet and be supported on a shallow,
reinforced concrete mat foundation . At th ese depths, dense sand with gravel and very
hard claystone bedrock was encountered in Boring No . B-12. Therefore, the lift station
can be supported on a reinforced concrete mat foundation bearing directly on the dense
sand with gravel or if the final bottom elevation of the lift station is less than 2 feet
above the top of bedrock elevation , then we recommend the bedrock below the
foundation bearing elevation should be over-excavated to allow for construction of at
least a 2 -foot-thick l ayer of moisture conditioned, properly compacted recycled concrete
base course over the claystone bedrock. The mat foundation should then bear directly on
the layer of recycled co ncrete base course. The recycled concrete base course layer
should help provide a more uniform bearing subgrade for the lift station and reduce the
potential risk for movements from the bedrock once exposed and wetted. Design
recommendations for foundations for the proposed structure and related structural
elements are presented in the Shallow Foundations section of this report.
Pavements
Our opinion of pavement section thickness design has been developed based on our
understanding of the intended use, assumed traffic, and subgrade preparation
recommended herein per LCUASS standards using the 1993 AASHTO (American
Association of State Highway and Tr ansportation Officials) pavement design
methodology presented in the LCUASS manual. The Pavements section includes our
recommendations regarding minimum pavement component thickness es.
The recommendations contained in this report are based upon the results of field and
laboratory testing (presented in the Exploration Results ), engineering analyses, and
our current understanding of the proposed project. The General Comments section
provides an understanding of the report limitations.
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials 11
Earthwork
Earthwork is anticipated to include demolition, site preparation, excavations, evaluation
of existing fill, subgrade preparation , soil stabilization (if needed) and engineered
fill/embankment placement. The following sections provide recommendations for use in
the preparation of specifications for the project . Recommendations include critical quality
criteria, as necessary, to render the site in the state considered in our geotechnical
engineering evaluation for foundations and pavements.
Demolition
Demolition/removal of any existing site imp rovements or features (such as existing
structures, pavements or surfacing materials , utilities, etc.) should include complete
removal of all below -grade structural elements (if any), pavements, and exterior
flatwork (if any) within the proposed construction area. This should include removal of
any utilities to be abandoned along with any loose utility trench backfill or loose backfill
found adjacent to existing foundations. All materials derived from the demolition of
existing structures and pavements should be removed from the site. The types of
foundation systems supporting the existing structures at the site are not known. If any
of the existing buildings are supported by drilled piers, the existing piers should be
truncated a minimum depth of 3 feet below areas of planned new construction.
Consideration could be given to re -using demolished asphalt and concrete (if any) as
engineered fill/embankment provided the materials are processed and uniformly blended
with the on -site soils. Asphalt and/or concrete materials when used as fill/embankment
should be processed to a maximum size of 2 inches and blended at a ratio of 30 percent
asphalt/concrete to 70 percent of on -site soils .
Site Preparation
Prior to placing fill/embankment, existing vegetation, topsoil, root mats, aggreg ate
surfacing, and pavements should be removed. Complete stripping of the topsoil should
be performed in the proposed lift station and pavement areas. As previously stated, we
also recommend complete removal of existing, undocumented fill within proposed
building/structure areas. Existing fill was encountered in our borings extending to depths
of about 2 to 7 feet below existing site grades. Existing fill need not be removed from
below new pavements i f the owner is willing to accept greater than normal risk of
movement below the planned pavements to reduce initial construction costs and the
subgrade preparat ion recommendations presented in the Existing, Undocument ed Fill
section of Geotechnical Overv iew are followed.
Stripped organic materials should be wasted from the site or used to re -vegetate
landscaped areas or exposed slopes after completion of grading operations. Prior to the
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials 12
placement of fill/embankment, the site should be graded to create a relatively level
surface to receive fill /embankment , and to provide for a relatively uniform thickness of
fill/embankment beneath proposed structures and pavements.
Any mature trees located within or near the proposed roadway alignment or the footprint
area of t he proposed lift station will require removal at the onset of construction. Tree
root systems can remove substantial moisture from surrounding soils. Where trees are
removed, the full root ball and all associated dry and desiccated soils should be
removed. The soil materials which contain less than 5 percent organics can be reused as
engineered fill/embankment provided the material is moisture conditioned and properly
compacted.
Although no evidence of underground facilities (such as septic tanks, cesspools,
basements, and utilities) was observed during the exploration and site reconnaissance,
such features could be encountered during construction. If unexpected fills or
underground facilities are encountered, such features should be removed, and the
excavation thoroughly cleaned prior to backfill placement and/or construction.
Excavation
We anticipate excavations for the proposed construction can be accomplished with
conventional earthmoving equipment. Excavations into the on -site soils will encounter
weak, soft /loose, and/or saturated soil conditions with possible caving conditions . The
bottom of excavations should be thoroughly cleaned of loose soils and disturbed
materials prior to fill/embankment placement and/or construction.
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 pro posed 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.
Excavation penetrating several feet into the bedrock (if any) may require the use of
specialized heavy -duty equipment, together with ripping or jack -hammering to advance
the excavation and facilitate rock break -up and removal. However, field penetration
resistance test results indicate the upper approximately 1 to 2 feet of bedrock may be
comparatively easier to excavate with conventional equipment. Consideration should be
given to obtaining a unit price for difficult excavation in the contract documents for the
project.
Any over-excavation extending below the bottom of foundation elevation should extend
laterally beyond all edges of the foundations at least 8 inches per foot of over -
excavation depth below the foundation base elevation. The over -excavation should be
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backfilled to the foundation base elevation in accordance with the recommendations
presented in this report.
Depending upon depth of excavation and seasonal conditions, surface water infiltration
and/or groundwater may be encountered in excavations on the site. We anticipate
pumping from sumps may be utilized to control water within excavations. Well points
may be required for significant groundwater flow, or where excavations penetrate
groundwater to a significant depth.
The subgrade soil conditions should be evaluated during the excavation process and the
stability of the soils determined at that time by the contractors’ Competent Person as
defined by OSHA. Slope inclinations flatter than the OSHA maximum values may have to
be used. The individual contractor(s) should be made responsible for designing and
constructing stable, temporary excavations as required to maintain stability of both the
excavation sides and bottom. All excavations should be sloped or shored in the in terest
of safety following local, and federal regulations, including current OSHA excavation and
trench safety standards. If any excavation, including a utility trench, is extended to a
depth of more than 20 feet, it will be necessary to have the side slopes and/or shoring
system designed by a professional engineer.
As a safety measure, we recommend all vehicles and soil piles be kept a t a minimum
lateral distance from the crest of the slope equal to the slope height. The exposed slope
face should be protected against the elements.
Subgrade Preparation
Based on the results of the laboratory testing, the on -site clayey soils are considered to
have low expansive potential . Therefore, no additional swell mi tigation measures w ill be
required below new pavements for this project according to Section 5.7 .2 of the LCUASS
manual.
After site preparation , removal of existing , undocumented fill (if required), and
completion of any required undercuts and recommended over-excavations below
structures and pavements , the top 12 inches of the exposed ground surface should be
scarified, moisture conditioned, and compacted to at least 95 percent of the maximum
dry unit weight as determined by AASHTO T99 before any new fill/embankment ,
foundations, and pavements are placed or constructed. Medium h ard to very hard
bedrock materials encountered at the bottom of excavations do not require scarification
and compaction prior to placement of engineered fill /embankment and/or new
construction .
Large areas of prepared subgrade should be proof rolled prior to new construction. Proof
rolling is not required in areas which are inaccessible to proof rolling equipment.
Subgrades should be proof rolled with an adequately loaded vehicle such as a fully -
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loaded tandem-axle dump truck. Proof rolling should be performed under the
observation of the Geotechnical Engineer or representative. Areas excessively deflecting
under the proof roll should be delineated and subsequently addressed by the
Geotechnical Engineer. Excessively wet or dry material should also either be removed
and replaced with engineered fill/embankment or scarified, moisture conditioned , and
compacted.
Our experience indicates the subgrade materials below existing pavements and flatwork
after demolition will likely have relatively high moisture content and will tend to deflect
and deform (pump) under construction traffic wheel loads. After removal of existing
pavements and flatwork, the contractor should expect unstable subgrade materials will
need to be stabilized prior to fill placement and/or construction. Consequently, Terracon
recommends a contingency be provided in the construction budget to stabilize and
correct weak/unstable subgrade.
After the bottom of excavation or subgrade has been prepared as recommended above,
engineered fill/embankment can be placed to bring the subgrade below the proposed lift
station or pavement subgrade to the desired grade. Engineered fill /embankment should
be placed in accordance with the recommendations presented in subsequent sections of
this report.
Subgrade Stabilization
Methods of subgrade stabilization/improvement, as described below, could include
scarification, moisture conditioning and compaction, removal of unstable materials and
replacement with granular fill (with or without geosynthetics), and chemical treatment.
The appropriate method of improvement, if required, would be dependent on factors
such as schedule, weather, the size of area to be stabilized, and the nature of the
instability. More detailed recommendations can be provided during construction as the
need for subgrade stabilization occurs . Performing site grading operations during warm
seasons and dry periods would help reduce the amount of subgrade stabilization
required.
If the exposed subgrade is unstable during proof rolling operations, it could be stabilized
using one of the methods described below.
■ Scarification and Compaction - It may be feasible to scarify, dry, and compact
the exposed soils. The success of this procedure would depend primarily upon
favorable weather and sufficient time to dry the soils. Stable subgrades likely
would not be achievable if the thickness of the unstable soil is greater than about
1 foot, if the unstable soil is at or near groundwater levels, or if construction is
performed during a period of wet or cool weather when drying is difficult.
■ Crushed Stone - The use of crushed stone or crushed concrete is a common
procedure to improve subgrade stability. Typical undercut depths would be
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expected to range from about 6 to 18 inches below finished subgrade elevation.
Crushed stone and/or concrete can be tracked or “crowded” into the unstable
subgrade until a stable working surface is attained. The use of high modulus
geosynthetics (i.e., geotextile or geogrid) could also be considered after
underground work such as utility construction is completed. Prior to placing the
geosynthetic, we recommend all below -grade construction, such as utility line
installation, be completed to avoid damaging the geosynthetic. Equipment should
not be operated above the geosynthetic until one full lift of crushed stone fill is
placed above it.
■ Chemical Treatment - Improvement of subgrades with portland cement , lime,
or fly ash could be considered for improving unstable soils. Chemical treatment
should be performed by a pre -qualified contractor having experience with
successfully treating subgrades in the project area on similar sized projects with
similar soil conditions. Results of chemical analysis of the chemical treatment
materials should be provided to the Geotechnical Engineer for review prior to use.
The hazards of chemicals blowing across the site or onto adjacent propert ies
should also be considered. Additional testing would be needed to develop specific
recommendations to improve subgra de stability by blending chemicals with the
site soils. Additional testing could include, but not be limited to, determining the
most suitable chemical treating agent, the optimum amounts required, the
presence of sulfates in the soil, and freeze -thaw durability of the subgrade.
Further evaluation of the need and recommendations for subgrade stabilization can be
provided during construction as the geotechnical conditions are exposed.
Fill/Embankment Material Types
Fill for this project should consist of engineered fill /embankment. Engineered
fill/embankment is fill that meets the criteria presented in this report and has been
properly documented. On -site soils free of deleterious materials or approved granular
and low plasticity cohesive imported materials may be used as fill /embankment material.
Bedrock excavated during construction should not be re used as fill /embankment below
new structures , slabs/flatwork, or pavements. The earthwork contractor should expect
significant mechanical processing and moisture conditioning of the site soils will be
needed to achieve proper compaction.
Imported fill materials (if required) should meet the following material property
requirements. Regardless of its source, engineered fill/embankment should consist of
approved materials that are free of organic matter and debris. Frozen material should
not be used, and fill/embankment should not be placed on a frozen subgrade.
Gradation Percent Finer by Weight (ASTM C136)
3 ” 100
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Gradation Percent Finer by Weight (ASTM C136)
1” 70-100
No. 4 Sieve 30-100
No. 200 Sieve 10-65
Soil Properties Values
Liquid Limit 35 (max.)
Plasticity Index 15 (max.)
Aggregate base course or recycled concrete base cour se used below new pavements or
the below-grade lift station foundation should meet Colorado Department of
Transportation (CDOT) requirements for Class 5 or 6 aggregate base course materials.
Other import ed fill material types may be suitable for use on the site depending upon
proposed application and location on the site and could be tested and approved for use
on a case-by-case basis.
Fill/Embankment Placement and Compaction Requirements
Engineered fill /embankment 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
Maximum 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 1
Engineered Fill /Embankment: At least 95% of the maximum dry
unit weight as determined by AASHTO T99 .
Engineered Fill /Embankment 8 Feet or Greater: At least 98% of
the maximum dry unit weight as determined by AASHTO T99 for
the entire depth of fill in areas receiving 8 feet of fill or greater.
Aggregate Base Course: At least 95% of maximum dry unit
weight as determined by AASHTO T180 in pavement areas.
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Item Description
Water Content
Range 2 ,3
Cohesive (clay): -1% to +3% of optimum moisture content
Granular (sand): -3% to +3% of optimum moisture content
1. We recommend engineered fill /embankment be tested for moisture content and
compaction during placement. If 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 requir ed until the specified moisture and
compaction requirements are achieved.
2. 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.
3. Specifically, moisture levels in granular soils should be maintained low enough to allow
for satisfactory compaction to be achieved without the fill material pumping when proof
rolled.
Utility Trench Backfill
Any loose, soft, or unsuitable materials encountered at the bottom of utility trench
excavations should be removed and replaced with engineered fill/embankment or
bedding material in accordance with public works specifications for the utility be
supported. This recommendation is particularly applicable to utility work where
settlement control of the utility is critical. Utility trench excavation should not be
conducted below a downward 1H:1V (Horizontal:Vertical) projection from existing
foundations without engineering review of shoring requirements and geotechnical
observation during construction.
On -site materials are considered suitable for backfill of utility and pipe trenches from
about the top of the pipe to subgrade elevation provided the material is free of organic
matter and deleterious substances.
All utility trench excavations should be made with sufficient working space to permit
construction including backfill placement and compaction. Utility trench backfill should
be placed and compacted as discussed earlier in this report. Compaction of initial lifts
should be accomplished with hand -operated tampers or other lightweight compactors.
Flooding or jetting for placement and compaction of backfill i s not recommended. If
utility trenches are backfilled with relatively clean granular material, they should be
capped with at least 18 inches of cohesive fill in non -pavement areas to reduce the
infiltration and conveyance of surface water through the trench backfill.
In areas of low permeability subgrades, utility trenches are a common source of water
infiltration and migration. Utility trenches penetrating beneath the building/structures
should be effectively sealed to restrict water intrusion and flow through the tre nches,
which could migrate below the building s. The trench should provide an effective trench
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plug that extends at least 5 feet from the face of the building exterior. The plug material
should consist of cementitious flowable fill or low permeability clay. The trench plug
material should be placed to surround the utility line. If used, the trench p lug material
should be placed and compacted to comply with the water content and compaction
recommendations for engineered fill stated previously in this report.
All underground piping within or near the proposed structures should be designed with
flexible couplings, so minor deviations in alignment do not result in breakage or distress.
Utility knockouts in foundation walls should be oversized to accommodate diffe rential
movements.
We recommend a representative of the Geotechnical Engineer provide full-time
observation and compaction testing of utility trench backfill within the project limits.
Grading and Drainage
All grades must be adjusted to provide effective drainage away from the proposed
pavements and subgrade , and new structures during construction and should be
maintained throughout the life of the proposed improvements. Infiltration of water into
excavations must be prevented during construction. Water permitted to pond near or
adjacent to structures or pavement subgrade (either during or post -construction) can
result in significantly higher soil movements than those discussed in this report. As a
result, any estimations of potential movement described in this report cannot be relied
upon if positive drainage is not obtained and maintained, and water is allowed to
infiltrate the fill and/or subgrade.
Exposed ground should be sloped and maintained at a minimum of 5% away from the
proposed structure for at least 10 feet beyond the perimeter of the lift station . Locally,
flatter grades may be necessary to transition ADA access requirements for flatwork.
After building construction and landscaping have been completed, final grades should be
verified to document effective drainage has been achieved. Grades around the structure
should also be periodically inspected and adjusted, as necessary, as part of the
structure’s maintenance program.
F latwork and 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 flatwork, particularly if such movement would be critical.
Where paving or flatwork abuts the structures, care should be taken that joints are
properly sealed and maintained to prevent the infiltration of surface water.
Planters located adjacent to structures (if any) should preferably be self -contained.
Sprinkler mains and spray heads should be located a minimum of 5 feet away from the
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building lines. Low -volume, drip style landscaped irrigation should be used sparingly
near the buildings/structures.
Exterior Slab Design and Construction
Exterior slabs on -grade, sidewalks, concrete flatwork, curb, and utilities founded on or in
embankment fills or the site soils will likely experience some movement due to the
volume change of the material. Subgrade soils below new fill/embankment should be
scarified to a depth of at least 12 inches, moisture conditioned, and compacted prior to
placement of new fill/embankment, aggregate base course, or pavement materials.
Potential movement could be reduced by:
■ Minimizing moisture increases in the subgrade soils and new fill/embankment
■ Controlling moisture -density during preparation of the subgrade and placement of
new fill/embankment
■ Using designs which allow vertical movement between the exterior features and
adjoining structural elements (if any)
■ Placing control joints on relatively close centers
Earthwork Construction Considerations
Upon completion of filling and grading, care should be taken to maintain the subgrade
water content prior to construction of grade -supported improvements such as flatwork
and pavements. Construction traffic over the completed subgrades should be avoided.
The site should also be graded t o prevent ponding of surface water on the prepared
subgrades or in excavations. Water collecting over or adjacent to construction areas
should be removed. If the subgrade freezes, desiccates, saturates, or is disturbed, the
affected material should be removed and replaced , or the materials should be scarified,
moisture conditioned, and compacted prior to pavement or flatwork construction.
Construction site safety is the sole responsibility of the contractor who controls the
means, methods, and sequencing of construction operations. Under no circumstances
shall the information provided herein be interpreted to mean Terracon is assuming
responsibility for construction site safety or the contractor's activities; such
responsibility shall neither be implied nor inferred.
Excavations or other activities resulting in ground disturbance have the potential to
affect adjoining structures. Our scope of services does not include review of available
final grading information or consider potential temporary grading performed by the
contractor for potential effects such as ground movement beyond the project limits. A
preconstruction/precondition survey should be conducted to document nearby
infrastructure prior to any site development activity. Excavation or ground disturbance
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activities adjacent or near property lines should be monitored or instrumented for
potential ground movements that could negatively affect adjoining structures.
Construction Observation and Testing
The earthwork efforts should be observed by the Geotechnical Engineer (or others under
their direction). Observation should include documentation of adequate removal of
surficial materials (vegetation, topsoil, and existing aggregate surfacing and
pavements), evaluation and remediation of existing fill materials, subgrade stabilization,
as well as proof rolling and mitigation of unsuitable areas delineated by the proof roll.
Each lift of engineered fill/embankment should be tested, evaluated, and reworked, as
necessary, as recommended by the Geotechnical Engineer prior to placement of
additional lifts.
In areas of excavations, the subgrade and exposed condition s at the base of the
recommended over-excavation should be evaluated by the Geotechnical Engineer. If
unanticipated conditions are observed, the Geotechnical Engineer should prescribe
mitigation options.
In addition to the documentation of the essential parameters necessary for construction,
the continuation of the Geotechnical Engineer into the construction phase of the project
provides the continuity to maintain the Geotechnical Engineer’s evaluation of subsurface
conditions, including assessing variations and associated design changes.
Shallow Foundations
If the has been prepared in accordance with the requirements noted in Geotechnical
Overview and Earthwork, the following design parameters are applicable for shallow ,
reinforced concrete mat foundations for the lift station structure. The recommendations
presented below are based on the subsu rface profile encountered in Boring No. B-12. If
the lift station location is moved away from the location of Boring No. B-12, then the
Geotechn ical Engineer should be provided the opportunity to review , and possible revise ,
these recommendations based on the subsurface profile anticipated at the updated lift
station location.
Reinforced Mats – Design Recommendations
Item Description
Maximum Net Allowable Bearing
Pressure 1 5,000 psf
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Item Description
Anticipated Foundation Bearing
Depth About 15 to 20 feet below existing grades
Required Bearing Stratum 2
At least 2 feet of moisture conditioned ,
properly compacted recycled c oncrete base
course over very hard claystone bedrock if
bottom of foundation elevation is within 2
feet of top of bedrock
OR
Properly prepared dense native sand with
gravel soils
Anticipated Mat Foundation
Dimensions 15 feet by 15 feet or less
Lateral Earth Pressure Coefficients 3
On -site clay soil and engineered fill :
Active, Ka = 0.49
Passive, Kp = 2.04
At-rest, Ko = 0.66
On -site granular soil and engineered fill :
Active, Ka = 0.33
Passive, Kp = 3.00
At-rest, Ko = 0.50
Sliding Resistance
On -site granular soil and engineered fill :
μ = 0.43 (ultimate)
Recycled concrete base course :
μ = 0.50 (ultimate)
Moist Soil Unit Weight
On -site clay soil and engineered fill :
γ = 120 pcf
On -site granular soil and engineered fill :
γ = 115 pcf
Recycled concrete base course:
γ = 135 pcf
Minimum Embedment Below
Finished Grade 4
Exterior foundations in unheated areas:
30 inches
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Item Description
Subgrade Modulus
k1 = 175 psi/in . (properly prepared dense
native sand with gravel soils)
k1 = 200 psi/in. (on a minimum 2 feet of
recycled concrete base course o ver
claystone bedrock if foundation bearing
elevation is within 2 feet of top of bedrock )
𝐾(𝐵𝑥𝐵)=𝑘1 (𝐵+1
2𝐵)
2 (sands)
𝐾(𝐵𝑥𝐿)=
𝐾(𝐵𝑥𝐵)(1 +0.5 ∗(𝐵
𝐿))
1.5
Where:
k1 = coefficient of subgrade reaction of
foundations measuring 1 ft. x 1 ft.
K (BxB) = coefficient of subgrade modulus
for a square foundation having
dimensions B (ft.) x B (ft.).
K (BxL) = coefficient of subgrade modulus
for a rectangular foundation having
dimensions B (ft.) x L (ft.).
Estimated Total Movement 5 About 1 inch or less
Estimated Differential Movement 5 About ½ to ¾ of total movement
1. The maximum net allowable bearing pressure is the pressure in excess of the minimum
surrounding overburden pressure at the foundation base elevation. Values assume
exterior grades are no steeper than 20% within 10 feet of structure. The design bearing
pressure may be increased by one -third when considering the alternative load
combination s of Section 1605.3.2 of the 2018 International Building Code ; however, it
should not be increased when loads are determined by the basic allowable stress design
load combinations of Section 1605.3.1 .
2. Unsuitable or soft/loose soils should be over -excavated and replaced with engineered
fill/embankment per the recommendations presented in Earthwork.
3. Use of lateral earth pressures require the foundation forms be removed and compacted
engineered fill/embankment be placed against the vertical foundation face. Assumes no
hydrostatic pressure. The lateral earth pressure coefficients are ultimate values and do
not include a factor of safety. The foundation designer should include the appropriate
factors of safety.
4. Embedment necessary to minimize the effects of frost and/or seasonal water content
variations. For sloping ground, maintain depth below the lowest adjacent exterior grade
within 5 horizontal feet of the structure.
5. The estimated movements presented above assume the maximum foundation dimension
presented in the table above . Larger foundation footprints will likely require reduced net
allowable soil bearing pressures to reduce risk for potential settlement.
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Foundations should be proportioned to reduce differential foundation movement.
Proportioning on the basis of equal total settlement is recommended; however,
proportioning to relative constant dead -load pressure will also reduce differential
movement between adjacent foundations. Foundations should be reinforced as
necessary to reduce the potential for distress caused by differential foundation
movement.
Foundation excavations should be observed by Terracon. If the soil conditions
encountered differ significantly from those presented in this report, supplemental
recommendations will be required.
Any over-excavation extending below the bottom of foundation elevation should extend
laterally beyond all edges of the foundations at least 8 inches per foot of over -
excavation depth below the foundation base elevation. The over -excavation should be
backfilled to the foundation base e levation in accordance with the recommendations
presented in this report.
Shallow Foundation Construction Considerations
F oundation excavations should be evaluated under the observation of the Geotechnical
Engineer. The base of all foundation excavations should be free of water and loose soil,
prior to placing concrete. Concrete should be placed soon after excavating to reduce
bearing soil disturbance. Care should be taken to prevent wetting or drying of the
bearing materials during construction. Excessively wet or dry material or any
loose/disturbed material in the bottom of foundation excavations should be
removed/reconditioned before foundation concrete is placed.
To reduce the potential of “pumping” and softening of the foundation soils at the
foundation bearing level and the requirement for corrective work, we suggest the
foundation excavation for the building/structure be completed remotely with a track -hoe
operating outside of the excavation limits.
Foundation elements should be reinforced as necessary to reduce the potential for
distress caused by differential foundation movement.
Unstable subgrade conditions encountered in foundation excavations should be observed
by Terracon to assess the subgrade and provide suitable alternatives for stabilization.
Typical methods of stabilization/improvement are presented in the Subgrade
Stabilization section of Earthwork.
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Below-Grade Structures
We understand a new lift station is planned to be construct ed as part of the Harmony
Lakes development. The l ift station is anticipated to extend about 15 to 20 feet below
existing grades and observed g roundwater levels.
Lateral Earth Pressures
Design Parameters
Structures with unbalanced backfill levels on opposite sides should be designed for earth
pressures at least equal to values indicated in the following table. Earth pressures will be
influenced by structural design of the walls, conditions of wall restrain t, methods of
construction, and/or compaction and the strength of the materials being restrained. Two
wall restraint conditions are shown in the diagram below. Active earth pressure is
commonly used for design of free -standing cantilever retaining walls an d assumes wall
movement. The “at -rest” condition assumes no wall movement and is commonly used
for basement walls, loading dock walls, or other walls restrained at the top. The
recommended design lateral earth pressures do not include a factor of safety an d do not
provide for possible hydrostatic pressure on the walls (unless stated).
Lateral Earth Pressure Design Parameters
Earth
Pressure
Condition 1
Coefficient for
Backfill Type 2
Surcharge
Pressure 3
p1 (psf)
Equivalent Fluid Pressures
(psf) 2,4
Unsaturated 5 Submerged 5
Active (K a) Granular - 0.33
Fine Grained - 0.49
(0.33)S
(0.49)S
(45)H
(60)H
(85)H
(90)H
At -Rest (K o) Granular - 0.50
Fine Grained - 0.66
(0.50)S
(0.66)S
(65)H
(80)H
(95)H
(100)H
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Lateral Earth Pressure Design Parameters
Earth
Pressure
Condition 1
Coefficient for
Backfill Type 2
Surcharge
Pressure 3
p1 (psf)
Equivalent Fluid Pressures
(psf) 2,4
Unsaturated 5 Submerged 5
Passive (K p) Granular – 3.00
Fine Grained - 204
---
---
---
---
---
---
1. For active earth pressure, wall must rotate about base, with top lateral movements 0.002
H to 0.004 H, where H is wall height. For passive earth pressure, wall must move
horizontally to mobilize resistance. Fat clay or other expansive soils should not be used
as backfill behind the wall .
2. Uniform, horizontal backfill, with a maximum unit weight of 120 pcf for cohesive soils and
115 pcf for granular soils.
3. Uniform surcharge, where S is surcharge pressure.
4. Loading from heavy compaction equipment is not included.
5. To achieve “Unsaturated” conditions, drainage behind walls should be incorporated into
the design or the bottom of wall should be above groundwater levels . “Submerged”
conditions are recommended when drainage behind walls is not incorporated into the
design or where walls extend below groundwater levels .
Backfill placed against structures should consist of granular soils or low plasticity
cohesive soils. For the granular values to be valid, the granular backfill must extend out
and up from the base of the wall at an angle of at least 45 and 60 degrees from vertical
for the active case and passive cases, respectively . To calculate the resistance to sliding,
the values presented in the Shallow Foundation section can be utilized between wall
foundations and the dense sand with gravel soils or recycled concrete base course.
Footings, floor slabs , or other loads bearing on backfill behind walls may have a
significant influence on the lateral earth pressure. Placing footings within wall backfill
and in the zone of active soil influence on the wall should be avoided unless structural
analyses indicat e the wall can safely withstand the increased pressure.
The lateral earth pressure recommendations given in this section are applicable to the
design of rigid retaining walls subject to slight rotation, such as cantilever, or gravity
type concrete walls. These recommendations are not applicable to the design of modular
block - geogrid reinforced backfill walls (also termed MSE walls). Recommendations
covering these types of wall systems are beyond the scope of services for this
assignment. However, we would be pleased to develop a proposal for evaluation and
design of such wall systems upon request.
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P avements
General Pavement Commen ts
Pavement designs are provided for the traffic conditions and pavement life conditions as
noted in Project Description and in the following sections of this report. A critical
aspect of pavement performance is site preparation. Pavement designs noted in this
section must be applied to the site which has been prepared as recommended in the
Earthwork section and the following sections .
Pavements – Subgrade Preparation
On most project sites, the site grading is accomplished relatively early in the
construction phase. Fill/embankment is 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 suitab le 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.
Prior to pavement construction and after the pavement areas have been stripped, and
any required undercuts have been completed within the planned pavement a reas, the
top 12 inches of the exposed ground surface should be scarified, moisture conditioned,
and compacted as described in this report before any new fill/embankment, aggregate
base course, or pavement is placed or constructed. After the subgrade has been scarified
and compacted and before placement of new fill/embankment and pavement, we
recommend the subgrade be proof rolled as described above.
Pavemen ts – Design Reccomendations
Design of pavements for the project have been based on the procedures outlined in the
1993 Guideline for Design of Pavement Structures prepared by AASHTO, the Colorado
Department of Transportation (CDOT) Pavement Design Manual , and the Larimer County
Urban Area Street Standards (LCUASS).
A few samples of the materials encountered within the upper 3 feet of the borings were
selected for swell-consolidation testing. The samples exhibited less than 0.1 percent to
0.5 percent swell when wetted which is less than t he 2 percent criteria established by
LCUA SS for mitigation measures . Therefore, we recommend the upper 12 inches of the
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials 27
pavement subgrade be prepared as recommended above and Earthwork prior to
placement of new fill /embankment or con struction of pavement s.
Traffic patterns and anticipated loading conditions (actual and assumed values) were
presented in the Project Description section of this report. For our pavement thickness
design recommendations, we understand the new roa dway will be classified as a
collector. Therefore, we used a total design period EDLA value of 50 in the pavement
analysis. This EDLA value is equivalent to an 18-kip equivalent single -axle load (ESAL)
value of 365,000 for the design lane. These estimated 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 estimated values, the pavement thickness recommendations
may not be applicable. If actual traffic values exceed those presented above, 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 2.3 (with a design
serviceability loss of 2 .2) was utilized along with an inherent reliability of 85 percent and
an overall standard deviation of 0.44 (per LCUASS for collector roadways). Pavements
were designed with a traffic life of 20 years . Using an estimated design R -value of about
15 to account for seasonal vari ation s and subgrade variations be tween the exp loratory
borings, appropriate ESAL, environmental criteria and other factors, the structural
numbers (SN) of the pavement sections were determined based on the 1993 AASHTO
design equation.
Full-Depth Composite Asphalt Pavement Section Thickness
A recommended minimum asphalt pavement section is presented in the table below. The
recommended pavement section thickness meet s or exceed s the minimum asphalt
section thickness required in LCUASS .
Recommended Minimum Asphalt Pavement Thicknesses (inches)
Traffic Area Asphaltic Concrete
Surface
Aggregate Base
Course Total
New north-south
collector road 5.5 9 14.5
Aggregate base course should consist of a blend of sand and gravel which meets strict
specifications for quality and gradation. Use of materials meeting 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 9 5 percent of
the maximum dry unit weight as determined by AASHTO T180.
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials 28
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, j ob
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).
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 pavements, such as decorative landscaped areas, are sources for water
infiltration into surrounding pavement systems. Water can collect in the islands and
migrate into the surrounding subgrade soils thereby degrading support of the pavement.
Islands with raised concrete curbs, irrigated foliage, and low permeability near -surface
soils are particular areas of concern. The civil design for the pavements with these
conditions should include features to restrict or collect and discharge excess water from
the islands. Examples of features are edge drains connected to the stormwater collection
system, longitudinal subdrains, or other suitable outlets and impermeable barriers
preventing lateral migration of water such as a cutoff wall installed to a dep th below the
pavement structure.
In areas of prepared subgrade or partial thickness pavement, the contractor should limit
traffic to equipment necessary to construct the pavement section. Heavily loaded
vehicles operating on these surfaces may cause significant damage, resulting in
deterioration and reduction in pavement life.
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials 29
Pavements – Maintenance
The pavement sections represent minimum recommended thicknesses and, as such,
periodic upkeep should be anticipated. Preventive maintenance should be planned and
provided for through an on -going pavement management program. Maintenance
activities are inten ded to slow the rate of pavement deterioration and to preserve the
pavement investment. Pavement care consists of both localized (e.g., crack and joint
sealing and patching) and global maintenance (e.g., surface sealing). Additional
engineering consultation is recommended to determine the type and extent of a cost -
effective program. Even with periodic maintenance, some movements and related
cracking may still occur, and repairs may be required.
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.
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 ob servation 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 th at 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 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 th ird-
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 a nd 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
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials 30
estimator as there may be variations on the site that are not apparent in the data that
could significantly affect 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 supp ort and dewatering requirements/design are the responsibility of others.
Construction and site development have the potential to affect adjacent properties. Such
impacts can include damages due to vibration, modification of groundwater/surface
water flow during construction, foundation movement due to undermining or subsidence
from excavation , as well as noise or air quality concerns. Evaluation of these items on
nearby properties are commonly associated with contractor means and methods and are
not addressed in this report. The owner and contractor should consider a
preconstruction/precondition survey of surrounding development. 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.
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials
Figures
Contents:
GeoModel (2 pages)
4,810
4,815
4,820
4,825
4,830
4,835
4,840
4,845
4,850
EL
E
V
A
T
I
O
N
(
M
S
L
)
(
f
e
e
t
)
Layering shown on this figure has been developed by the geotechnical
engineer for purposes of modeling the subsurface conditions as
required for the subsequent geotechnical engineering for this project.
Numbers adjacent to soil column indicate depth below ground surface.
NOTES:
Legend
This is not a cross section. This is intended to display the Geotechnical Model only. See individual logs for more detailed conditions.
GeoModel
4315 E. Harmony Road | Fort Collins, Colorado
Terracon Project No. 20255045
Harmony Lakes - New Convenience Store
Fort Collins, CO
Third Water Observation
Second Water Observation
First Water Observation
Groundwater levels are temporal. The levels shown are representative of
the date and time of our exploration. Significant changes are possible
over time.
Water levels shown are as measured during and/or after drilling. In
some cases, boring advancement methods mask the presence/absence
of groundwater. See individual logs for details.
Sandy Lean
Clay/Clayey Sand
Lean Clay Poorly-graded Sand
with Gravel
Claystone Lean Clay with Sand
Sandy Lean Clay
with Gravel
Well-graded Sand
with Gravel
Silty Sand with
Gravel
Clayey Sand with
Gravel
Poorly-graded Sand
with Silt and Gravel Asphalt
Model Layer Layer Name General Description
1
About 3 to 19 inches of aggregate surfacing in Boring Nos.
B-1 to B-5, B-7 to B-9, B-11, and B-12. About 3-1/4 inches
of asphalt in Boring No. B-6.
3 Very soft to stiff clay soils with variable amounts of sand
and gravel.
4 Very loose to very dense poorly graded and well graded
sand soils with variable amounts of fines and gravel.
2
Consisted primarily of clay soils with variable amounts of
sand and gravel or sand soils with variable amounts of clay
and gravel.
5 Medium hard to very hard claystone bedrock.
B-1 B-2
B-3
B-4
B-5
B-6
4862 Innovation Dr Ste 104
Aggregate SurfacingExisting Surfacing
Materials
Clay Soils
Sand Soils
Existing Fill
Bedrock
1
2
3
4
5
9.9
14
1
7
14
19
34.3
1
2
3
4
5
8.6
14
0.7
4
14
19
34.3
1
3
4
5
4.9
7
1.6
4
19
24.4
1
2
3
4
5
6.3
14
0.3
4
9
19.5
24.3
1
2
4
5
10
7
0.3
4
20.4
24.3
7.3
1
2
4
7
0.3
7
10.5
4,810
4,815
4,820
4,825
4,830
4,835
4,840
4,845
4,850
EL
E
V
A
T
I
O
N
(
M
S
L
)
(
f
e
e
t
)
Layering shown on this figure has been developed by the geotechnical
engineer for purposes of modeling the subsurface conditions as
required for the subsequent geotechnical engineering for this project.
Numbers adjacent to soil column indicate depth below ground surface.
NOTES:
Legend
This is not a cross section. This is intended to display the Geotechnical Model only. See individual logs for more detailed conditions.
GeoModel
4315 E. Harmony Road | Fort Collins, Colorado
Terracon Project No. 20255045
Harmony Lakes - New Convenience Store
Fort Collins, CO
Third Water Observation
Second Water Observation
First Water Observation
Groundwater levels are temporal. The levels shown are representative of
the date and time of our exploration. Significant changes are possible
over time.
Water levels shown are as measured during and/or after drilling. In
some cases, boring advancement methods mask the presence/absence
of groundwater. See individual logs for details.
Clayey Sand
Lean Clay with Sand Poorly-graded Sand
with GravelPoorly-graded Sand
with Clay and
Gravel
Poorly-graded Sand
Well-graded Sand
with Gravel
Sandy Lean Clay
with Gravel
Well-graded Sand
with Silt and Gravel Claystone
Sandy Lean
Clay/Clayey Sand
Poorly-graded Sand
with Silt and Gravel
Model Layer Layer Name General Description
1
About 3 to 19 inches of aggregate surfacing in Boring Nos.
B-1 to B-5, B-7 to B-9, B-11, and B-12. About 3-1/4 inches
of asphalt in Boring No. B-6.
3 Very soft to stiff clay soils with variable amounts of sand
and gravel.
4 Very loose to very dense poorly graded and well graded
sand soils with variable amounts of fines and gravel.
2
Consisted primarily of clay soils with variable amounts of
sand and gravel or sand soils with variable amounts of clay
and gravel.
5 Medium hard to very hard claystone bedrock.
B-7
B-8
B-9 B-10
B-11
B-12
4862 Innovation Dr Ste 104
Aggregate SurfacingExisting Surfacing
Materials
Clay Soils
Sand Soils
Existing Fill
Bedrock
1
2
3
4
7.37
1
4
7
10.5
1
2
47
0.3
2
10.5
1
2
3
4
5
3.2
9
0.9
7
9
14.5
24.3
2
4
5
7
14
24.1
2.2
1
2
4
5
9
14
1
7
22
24.3
1
2
4
5
9.5
7
1
4
19
34.3
3.7
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials
Attachments
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials
Exploration and Testing Procedures
Field Exploration
Number of Borings Approximate Boring
Depth (feet) Location
2 1
(Boring Nos. B-1 and B-2)
34.3 Proposed convenience
store location
1 1
(Boring No. B -3)
24.4 Proposed fuel tank area
2 1
(Boring Nos. B-4 and B-5)
24.3 Proposed canopy/fuel
dispenser area
3
(Boring Nos. B -6
through B-8)
10.5 Proposed roadway
alignment
3
(Boring Nos. B -9
through B-11)
24.1 to 24.3 In areas of f uture
developments
1
(Boring No. B-12) 34.3 Proposed lift station
location
1. A separate report utilizing the data from Boring Nos. B -1 through B-5 was issued to
provide geotechnical recommendations for the planned convenience store and fueling
station within the Harmony Lakes development (see our Geotechnical Engineering
Report dated October 21, 2025; Terracon Project No. 20255045).
Boring Layout and Elevations: Terracon personnel provided the boring layout using
handheld GPS equipment (estimated horizontal accuracy of about ±15 feet) and
referencing existing site features. Approximate ground surface elevations at the boring
locations were obtained by interpolation from a topographic site plan provided by TB
group dated April 5, 2024 . If elevations and a more precise boring layout are desired,
we recommend the borings be surveyed.
Subsurface Exploration Procedures: We advanced the borings with a truck -mounted
drill rig using continuous -flight , hollow -stem and solid-stem augers. Sampling was
performed using standard split-barrel and modified California barrel sampling
procedures. Bulk samples of auger cuttings from the upper approximately 5 feet of each
borehole were also collected for laboratory testing. In the split-barrel sampling
procedure, a standard 2 -inch outer diameter split -barrel sampling spoon was driven into
the ground by a 140 -pound automatic hammer falling a distance of 30 inches. The
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials
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 bor ing logs
at the test depths. In 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 spoon sampling proced ure; however,
blow counts are typically recorded for 6 -inch intervals for a total of 12 inches of
penetration. Modified California barrel sampler blow counts are not considered N -values.
The samples were placed in appropriate containers and taken to our soil laboratory for
testing and classification by a Geotechnical Engineer.
We also observed the boreholes while drilling and at the completion of drilling for the
presence of groundwater . Additionally, we observed 3 of the boreholes approximately 24
hours after the completion of drilling for the presence of groundwater. The groundwater
levels are shown on the attached boring logs.
Our exploration team prepared field boring logs as part of the drilling operations. The
sampling depths, penetration distances, and other sampling information were recorded
on the field boring logs. These field logs included visual classifications of the materials
observed during drilling and our interpretation of the subsurface conditions between
samples. Final boring logs were prepared from the field logs. The final boring logs
represent the Geotec hnical Engineer's interpretation of the subsurface conditi ons at the
boring locations based on field data, observation of samples, and laboratory test results.
We backfilled the borings with auger cuttings or cementitious flowable backfill after
completion of drilling. The pavement at the location of Boring No. B -6 was patched with
the asphalt core and Utilibond . Our services did not include repair of the site beyond
backfilling the boreholes and patching existing pavement. 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.
Laboratory Testing
The project engineer reviewed the field data and assigned laboratory tests. The
laboratory testing program included the following types of tests:
■ Moisture Content
■ Dry Unit Weight
■ Atterberg Limits
■ Grain-size Distribution
■ One-dimensional Swell/Consolidation
■ R -value
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials
■ Water-soluble Sulfates
■ Corrosivity Suite – pH, sulfates, chloride ion, sulfide ion, redox, total salts and
electrical resistivity
The laboratory testing program included examination of samples by an engineer and/or
geologist. Based on the results of our field and laboratory programs, we described and
classified the soil samples in accordance with the Unified Soil Classification System. A
brief description of this classification system as well as the General Notes can be found
in the Supporting Information section. Rock classification was conducted using locally
accepted practices for engineering purposes .
Laboratory test results are indicated on the boring logs and are presented in depth in
the Exploration Results section. Laboratory tests are performed in general accordance
with applicable local standards or other acceptable standards. In some cases, variations
to methods are applied as a result of local practice or professional judgement.
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials
Site Location and Exploration Plans
Contents:
Site Location Plan
Exploration Plan
Note: All attachments are one page unless noted above.
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials
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 Location
DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY MICROSOFT BING MAPS
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials
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 Plan
DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY MICROSOFT BING MAPS
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials
Exploration and Laboratory Results
Contents:
Boring Logs (B-1 through B-12)
Atterberg Limits
Grain Size Distribution (3 pages)
Consolidation/Swell (10 pages)
R -Value
Water-Soluble Sulfates
Corrosivity Suite
Note: All attachments are one page unless noted above.
4846
4840
4833
4828
4812.7
AGGREGATE SURFACING, about 12 inches thick
FILL - SANDY LEAN CLAY (CL), trace gravel, brown
LEAN CLAY, dark brown, medium stiff, iron oxide
present at about 9 feet
POORLY GRADED SAND WITH GRAVEL, fine to
medium grained, light brown with pink, medium
dense, possible cobbles
CLAYSTONE, yellow brown to gray, hard to very
hard, upper 1 to 2 feet is moderately weathered
Boring Terminated at 34.3 Feet
Boring Log No. B-1
Wa
t
e
r
L
e
v
e
l
Ob
s
e
r
v
a
t
i
o
n
s
De
p
t
h
(
F
t
.
)
5
10
15
20
25
30
Facilities | Environmental |Geotechnical | Materials
Approximate Elevation: 4847 (Ft.)
Gr
a
p
h
i
c
L
o
g
Mo
d
e
l
L
a
y
e
r
54.312.1
12.3
26.5
29.0
13.4
19.4
14.1
16.9
15.4
28-15-13
1.0
7.0
14.0
19.0
34.3
<+0.1/
500
<-0.1/
1000
115
93
119
108
6-7-10
N=17
5-7
12/12"
2-2-3
N=5
3-3
6/12"
2-7-17
N=24
14-22-34
N=56
30-50/3"
50/5"
50/3"
Advancement Method
4-1/4 inch inside-diameter, continuous-flight,
hollow-stem augers
Notes
Water Level Observations
9.9 feet at completion of drilling
14 feet while drilling
See Exploration and Testing Procedures for a description of field and laboratory proceduresused and additional data (If any).
See Supporting Information for explanation of symbols and abbreviations.
Elevation Reference: Elevation interpolated from a topographic site plan provided by TB Group.
Classification of rock estimated from disturbed samples. Core samples and petrographicanalysis may reveal other rock types.
Harmony Lakes - New Convenience Store
4315 E. Harmony Road | Fort Collins, Colorado
Terracon Project No. 20255045 Fort Collins, CO
Drill Rig
CME 55
Driller
Terracon
Logged by
A. Ellis
Boring Started
09-03-2025
Boring Completed
09-03-2025
Abandonment Method
Boring backfilled with auger cuttings upon
completion.
Sa
m
p
l
e
T
y
p
e
Pe
r
c
e
n
t
Fi
n
e
s
Wa
t
e
r
Co
n
t
e
n
t
(
%
)
Atterberg
Limits
Hammer Type
Automatic; Hammer
Efficiency = 93%
LL-PL-PI
See Exploration PlanLocation:
Latitude: 40.5223° Longitude: -104.9964°
Depth (Ft.)
Sw
e
l
l
-
C
o
n
s
o
l
/
Lo
a
d
(
%
/
p
s
f
)
Dr
y
U
n
i
t
We
i
g
h
t
(
p
c
f
)
Fi
e
l
d
T
e
s
t
Re
s
u
l
t
s
4862 Innovation Dr Ste 104
1
2
3
4
5
4847.3
4844
4839
4834
4829
4813.7
AGGREGATE SURFACING, about 8 inches thick
FILL - LEAN CLAY WITH SAND, trace gravel, dark
brown
LEAN CLAY, dark brown, stiff, organics at about 4
feet, increase in moisture at about 7 feet
soft to medium stiff at about 7 feet
SANDY LEAN CLAY WITH GRAVEL (CL), dark brown,
stiff
WELL GRADED SAND WITH GRAVEL, medium to
coarse grained, light brown with pink, medium dense,
possible cobbles
CLAYSTONE, gray, hard to very hard, upper 1 to 2
feet is moderately weathered
Boring Terminated at 34.3 Feet
Boring Log No. B-2
Wa
t
e
r
L
e
v
e
l
Ob
s
e
r
v
a
t
i
o
n
s
De
p
t
h
(
F
t
.
)
5
10
15
20
25
30
Facilities | Environmental |Geotechnical | Materials
Approximate Elevation: 4848 (Ft.)
Gr
a
p
h
i
c
L
o
g
Mo
d
e
l
L
a
y
e
r
51.0
0.7
4.0
9.0
14.0
19.0
34.3
+0.2/
500 115
121
4-5-7
N=12
5-9
14/12"
1-2-2
N=4
3-15
18/12"
9-10-12
N=22
10-19-45
N=64
50/4"
50/5"
50/4"
15.4
14.8
27.6
21.2
6.9
16.8
11.7
13.8
14.2
31-20-11
Advancement Method
4-1/4 inch inside-diameter, continuous-flight,
hollow-stem augers
Notes
Water Level Observations
8.6 feet at completion of drilling
14 feet while drilling
See Exploration and Testing Procedures for a description of field and laboratory proceduresused and additional data (If any).
See Supporting Information for explanation of symbols and abbreviations.
Elevation Reference: Elevation interpolated from a topographic site plan provided by TB Group.
Classification of rock estimated from disturbed samples. Core samples and petrographicanalysis may reveal other rock types.
Harmony Lakes - New Convenience Store
4315 E. Harmony Road | Fort Collins, Colorado
Terracon Project No. 20255045 Fort Collins, CO
Drill Rig
CME 55
Driller
Terracon
Logged by
A. Ellis
Boring Started
09-04-2025
Boring Completed
09-04-2025
Abandonment Method
Boring backfilled with auger cuttings upon
completion.
Sa
m
p
l
e
T
y
p
e
Pe
r
c
e
n
t
Fi
n
e
s
Depth (Ft.)
Sw
e
l
l
-
C
o
n
s
o
l
/
Lo
a
d
(
%
/
p
s
f
)
Hammer Type
Automatic; Hammer
Efficiency = 93%
Dr
y
U
n
i
t
We
i
g
h
t
(
p
c
f
)
Fi
e
l
d
T
e
s
t
Re
s
u
l
t
s
Wa
t
e
r
Co
n
t
e
n
t
(
%
)
Atterberg
Limits
LL-PL-PI
See Exploration PlanLocation:
Latitude: 40.5222° Longitude: -104.9960°
4862 Innovation Dr Ste 104
1
2
3
4
5
4844.4
4842
4837
4827
4821.6
AGGREGATE SURFACING, about 19 inches thick
LEAN CLAY WITH SAND, dark brown, stiff, possible
organics at about 2 feet
SILTY SAND WITH GRAVEL (SM), medium grained,
dark brown, medium dense to dense
WELL GRADED SAND WITH GRAVEL, medium to
coarse grained, light brown with pink, medium dense
to very dense, possible cobbles
CLAYSTONE, gray, very hard
Boring Terminated at 24.4 Feet
Boring Log No. B-3
Wa
t
e
r
L
e
v
e
l
Ob
s
e
r
v
a
t
i
o
n
s
De
p
t
h
(
F
t
.
)
5
10
15
20
Facilities | Environmental |Geotechnical | Materials
Approximate Elevation: 4846 (Ft.)
Gr
a
p
h
i
c
L
o
g
Mo
d
e
l
L
a
y
e
r
21.3
15.5
10.4
10.2
8.6
11.7
16.2
14.8
18-15-3
1.6
4.0
9.0
19.0
24.4
<+0.1/
150 113
115
4-7
11/12"
14-5-6
N=11
10-12-22
N=34
16-16-11
N=27
20-22-40
N=62
50/6"
50/5"
Advancement Method
4-1/4 inch inside-diameter, continuous-flight,
hollow-stem augers
Notes
Water Level Observations
4.9 feet at completion of drilling
7 feet while drilling
See Exploration and Testing Procedures for a description of field and laboratory proceduresused and additional data (If any).
See Supporting Information for explanation of symbols and abbreviations.
Elevation Reference: Elevation interpolated from a topographic site plan provided by TB Group.
Classification of rock estimated from disturbed samples. Core samples and petrographicanalysis may reveal other rock types.
Harmony Lakes - New Convenience Store
4315 E. Harmony Road | Fort Collins, Colorado
Terracon Project No. 20255045 Fort Collins, CO
Drill Rig
CME 55
Driller
Terracon
Logged by
A. Ellis
Boring Started
09-04-2025
Boring Completed
09-04-2025
Abandonment Method
Boring backfilled with auger cuttings upon
completion.
Sa
m
p
l
e
T
y
p
e
Pe
r
c
e
n
t
Fi
n
e
s
Wa
t
e
r
Co
n
t
e
n
t
(
%
)
Hammer Type
Automatic; Hammer
Efficiency = 93%
Atterberg
Limits
LL-PL-PI
See Exploration PlanLocation:
Latitude: 40.5223° Longitude: -104.9956°
Depth (Ft.)
Sw
e
l
l
-
C
o
n
s
o
l
/
Lo
a
d
(
%
/
p
s
f
)
Dr
y
U
n
i
t
We
i
g
h
t
(
p
c
f
)
Fi
e
l
d
T
e
s
t
Re
s
u
l
t
s
4862 Innovation Dr Ste 104
1
3
4
5
4848.7
4845
4840
4829.5
4824.7
AGGREGATE SURFACING, about 3 inches thick
FILL - SANDY LEAN CLAY, dark brown
SANDY LEAN CLAY (CL), dark brown, medium stiff,
possible calcium carbonate and organics at about 4
feet
no recovery of sample at 7 feet
very soft at about 7 feet
WELL GRADED SAND WITH GRAVEL, light brown
with pink, dense to very dense, possible cobbles
CLAYSTONE, gray, very hard, cementation at about
19.5 feet
Boring Terminated at 24.3 Feet
Boring Log No. B-4
Wa
t
e
r
L
e
v
e
l
Ob
s
e
r
v
a
t
i
o
n
s
De
p
t
h
(
F
t
.
)
5
10
15
20
Facilities | Environmental |Geotechnical | Materials
Approximate Elevation: 4849 (Ft.)
Gr
a
p
h
i
c
L
o
g
Mo
d
e
l
L
a
y
e
r
68.6
0.3
4.0
9.0
19.5
24.3
+0.2/
500 112
113
5-7
12/12"
2-2-3
N=5
0-1
1/12"
8-19-17
N=36
16-27-35
N=62
18-30-50/4"
50/4"
16.8
24.5
4.3
8.2
17.8
13.8
43-18-25
Advancement Method
4-1/4 inch inside-diameter, continuous-flight,
hollow-stem augers
Notes
Water Level Observations
6.3 feet at completion of drilling
14 feet while drilling
See Exploration and Testing Procedures for a description of field and laboratory proceduresused and additional data (If any).
See Supporting Information for explanation of symbols and abbreviations.
Elevation Reference: Elevation interpolated from a topographic site plan provided by TB Group.
Classification of rock estimated from disturbed samples. Core samples and petrographicanalysis may reveal other rock types.
Harmony Lakes - New Convenience Store
4315 E. Harmony Road | Fort Collins, Colorado
Terracon Project No. 20255045 Fort Collins, CO
Drill Rig
CME 55
Driller
Terracon
Logged by
A. Ellis
Boring Started
09-03-2025
Boring Completed
09-03-2025
Abandonment Method
Boring backfilled with auger cuttings upon
completion.
Sa
m
p
l
e
T
y
p
e
Pe
r
c
e
n
t
Fi
n
e
s
Depth (Ft.)
Sw
e
l
l
-
C
o
n
s
o
l
/
Lo
a
d
(
%
/
p
s
f
)
Hammer Type
Automatic; Hammer
Efficiency = 93%
Dr
y
U
n
i
t
We
i
g
h
t
(
p
c
f
)
Fi
e
l
d
T
e
s
t
Re
s
u
l
t
s
Wa
t
e
r
Co
n
t
e
n
t
(
%
)
Atterberg
Limits
LL-PL-PI
See Exploration PlanLocation:
Latitude: 40.5225° Longitude: -104.9960°
4862 Innovation Dr Ste 104
1
2
3
4
5
4846.7
4843
4838
4826.6
4822.7
FILL - AGGREGATE SURFACING, about 3 inches thick
FILL - CLAYEY SAND WITH GRAVEL, dark brown to
tan
POORLY GRADED SAND WITH GRAVEL, fine to
coarse grained, brown to pink, medium dense to
dense, possible cobbles
POORLY GRADED SAND WITH SILT AND GRAVEL
(SP-SM), medium to coarse grained, light brown with
pink, dense to very dense, possible cobbles
CLAYSTONE, yellow brown to gray, very hard, upper
1 to 2 feet is moderately weathered
Boring Terminated at 24.3 Feet
Boring Log No. B-5
Wa
t
e
r
L
e
v
e
l
Ob
s
e
r
v
a
t
i
o
n
s
De
p
t
h
(
F
t
.
)
5
10
15
20
Facilities | Environmental |Geotechnical | Materials
Approximate Elevation: 4847 (Ft.)
Gr
a
p
h
i
c
L
o
g
Mo
d
e
l
L
a
y
e
r
7.6
5.0
1.2
8.2
8.4
7.7
3.7
NP
0.3
4.0
9.0
20.4
24.3
112
107
3-4-4
N=8
8-20
28/12"
18-16-15
N=31
10-15-17
N=32
19-50/5"
25-30-14
N=44
50/4"
Advancement Method
4-1/4 inch inside-diameter, continuous-flight,
hollow-stem augers
Notes
Water Level Observations
7.3 feet after about 24 hours
10 feet at completion of drilling
7 feet while drilling
See Exploration and Testing Procedures for a description of field and laboratory proceduresused and additional data (If any).
See Supporting Information for explanation of symbols and abbreviations.
Elevation Reference: Elevation interpolated from a topographic site plan provided by TB Group.
Classification of rock estimated from disturbed samples. Core samples and petrographicanalysis may reveal other rock types.
Harmony Lakes - New Convenience Store
4315 E. Harmony Road | Fort Collins, Colorado
Terracon Project No. 20255045 Fort Collins, CO
Drill Rig
CME 55
Driller
Terracon
Logged by
A. Ellis
Boring Started
09-03-2025
Boring Completed
09-03-2025
Abandonment Method
Boring backfilled with auger cuttings upon
completion.
Sa
m
p
l
e
T
y
p
e
Pe
r
c
e
n
t
Fi
n
e
s
Wa
t
e
r
Co
n
t
e
n
t
(
%
)
Hammer Type
Automatic; Hammer
Efficiency = 93%
Atterberg
Limits
LL-PL-PI
See Exploration PlanLocation:
Latitude: 40.5225° Longitude: -104.9965°
Depth (Ft.)
Sw
e
l
l
-
C
o
n
s
o
l
/
Lo
a
d
(
%
/
p
s
f
)
Dr
y
U
n
i
t
We
i
g
h
t
(
p
c
f
)
Fi
e
l
d
T
e
s
t
Re
s
u
l
t
s
4862 Innovation Dr Ste 104
1
2
4
5
4848.7
4842
4838.5
ASPHALT, about 3-1/4 inches thick
FILL - CLAYEY SAND WITH GRAVEL (SC), angular to
subangular gravel, brown to dark brown with pink,
decrease in clay content at about 2.5 to 4 feet
WELL GRADED SAND WITH GRAVEL, brown with
pink and dark gray, medium dense
Boring Terminated at 10.5 Feet
Boring Log No. B-6
Wa
t
e
r
L
e
v
e
l
Ob
s
e
r
v
a
t
i
o
n
s
De
p
t
h
(
F
t
.
)
5
10
Facilities | Environmental |Geotechnical | Materials
Approximate Elevation: 4849 (Ft.)
Gr
a
p
h
i
c
L
o
g
Mo
d
e
l
L
a
y
e
r
16.63.5
11.2
8.9
9.3
21-13-8
0.3
7.0
10.5
<+0.1/
150
-0.2/
500
126
122
13-26
39/12"
10-11
21/12"
10-13-16
N=29
8-13-7
N=20
Advancement Method
4 inch diameter, continuous-flight, solid-stem
augers
Notes
Water Level Observations
7 feet while drilling
See Exploration and Testing Procedures for a description of field and laboratory proceduresused and additional data (If any).
See Supporting Information for explanation of symbols and abbreviations.
Elevation Reference: Elevation interpolated from a topographic site plan provided by TB Group.
Harmony Lakes - New Convenience Store
4315 E. Harmony Road | Fort Collins, Colorado
Terracon Project No. 20255045 Fort Collins, CO
Drill Rig
CME 55
Driller
Terracon
Logged by
A. Ellis
Hammer Type
Automatic; Hammer
Efficiency = 88%
Boring Started
09-26-2025
Boring Completed
09-26-2025
Abandonment Method
Boring backfilled with cementitious flowable fill and
capped with the asphalt core and utilibond.
Sa
m
p
l
e
T
y
p
e
Pe
r
c
e
n
t
Fi
n
e
s
Wa
t
e
r
Co
n
t
e
n
t
(
%
)
Atterberg
Limits
LL-PL-PI
See Exploration PlanLocation:
Latitude: 40.5228° Longitude: -104.9974°
Depth (Ft.)
Sw
e
l
l
-
C
o
n
s
o
l
/
Lo
a
d
(
%
/
p
s
f
)
Dr
y
U
n
i
t
We
i
g
h
t
(
p
c
f
)
Fi
e
l
d
T
e
s
t
Re
s
u
l
t
s
4862 Innovation Dr Ste 104
1
2
4
4846
4843
4840
4836.5
AGGREGATE SURFACING, about 12 inches thick
FILL - CLAYEY SAND WITH GRAVEL (SC), brown,
loose
LEAN CLAY WITH SAND, dark brown, stiff, possible
organics at about 4 feet
POORLY GRADED SAND WITH GRAVEL, light brown
with pink, very dense, possible cobbles
Boring Terminated at 10.5 Feet
Boring Log No. B-7
Wa
t
e
r
L
e
v
e
l
Ob
s
e
r
v
a
t
i
o
n
s
De
p
t
h
(
F
t
.
)
5
10
Facilities | Environmental |Geotechnical | Materials
Approximate Elevation: 4847 (Ft.)
Gr
a
p
h
i
c
L
o
g
Mo
d
e
l
L
a
y
e
r
37.043.1
16.6
7.3
29-14-15
1.0
4.0
7.0
10.5
+0.5/
150
+0.4/
500
94
114
4-7
11/12"
7-10
17/12"
20-35-47
N=82
20-23-23
N=46
Advancement Method
4-1/4 inch inside-diameter, continuous-flight,
hollow-stem augers
Notes
Water Level Observations
7.3 feet at completion of drilling
7 feet while drilling
See Exploration and Testing Procedures for a description of field and laboratory proceduresused and additional data (If any).
See Supporting Information for explanation of symbols and abbreviations.
Elevation Reference: Elevation interpolated from a topographic site plan provided by TB Group.
Harmony Lakes - New Convenience Store
4315 E. Harmony Road | Fort Collins, Colorado
Terracon Project No. 20255045 Fort Collins, CO
Drill Rig
CME 55
Driller
Terracon
Logged by
A. Ellis
Boring Started
09-04-2025
Boring Completed
09-04-2025
Abandonment Method
Boring backfilled with auger cuttings upon
completion.
Sa
m
p
l
e
T
y
p
e
Pe
r
c
e
n
t
Fi
n
e
s
Wa
t
e
r
Co
n
t
e
n
t
(
%
)
Hammer Type
Automatic; Hammer
Efficiency = 93%
Atterberg
Limits
LL-PL-PI
See Exploration PlanLocation:
Latitude: 40.5220° Longitude: -104.9964°
Depth (Ft.)
Sw
e
l
l
-
C
o
n
s
o
l
/
Lo
a
d
(
%
/
p
s
f
)
Dr
y
U
n
i
t
We
i
g
h
t
(
p
c
f
)
Fi
e
l
d
T
e
s
t
Re
s
u
l
t
s
4862 Innovation Dr Ste 104
1
2
3
4
4840.7
4839
4837
4834
4830.5
AGGREGATE SURFACING, about 3 inches thick
FILL - POORLY GRADED SAND WITH CLAY AND
GRAVEL, brown
POORLY GRADED SAND, fine to medium grained,
brown with pink, dense
POORLY GRADED SAND, medium to coarse grained,
light brown with pink, medium dense
WELL GRADED SAND WITH GRAVEL, light brown
with pink, dense, possible cobbles
Boring Terminated at 10.5 Feet
Boring Log No. B-8
Wa
t
e
r
L
e
v
e
l
Ob
s
e
r
v
a
t
i
o
n
s
De
p
t
h
(
F
t
.
)
5
10
Facilities | Environmental |Geotechnical | Materials
Approximate Elevation: 4841 (Ft.)
Gr
a
p
h
i
c
L
o
g
Mo
d
e
l
L
a
y
e
r
2.4
14.4
5.1
6.1
0.3
2.0
4.0
7.0
10.5
115
15-17-23
N=40
10-14
24/12"
16-20-22
N=42
21-24-35
N=59
Advancement Method
4-1/4 inch inside-diameter, continuous-flight,
hollow-stem augers
Notes
Water Level Observations
7 feet while drilling
See Exploration and Testing Procedures for a description of field and laboratory proceduresused and additional data (If any).
See Supporting Information for explanation of symbols and abbreviations.
Elevation Reference: Elevation interpolated from a topographic site plan provided by TB Group.
Harmony Lakes - New Convenience Store
4315 E. Harmony Road | Fort Collins, Colorado
Terracon Project No. 20255045 Fort Collins, CO
Drill Rig
CME 55
Driller
Terracon
Logged by
A. Ellis
Boring Started
09-04-2025
Boring Completed
09-04-2025
Abandonment Method
Boring backfilled with auger cuttings upon
completion.
Sa
m
p
l
e
T
y
p
e
Pe
r
c
e
n
t
Fi
n
e
s
Wa
t
e
r
Co
n
t
e
n
t
(
%
)
Atterberg
Limits
LL-PL-PI
See Exploration PlanLocation:
Latitude: 40.5212° Longitude: -104.9962°
Depth (Ft.)
Sw
e
l
l
-
C
o
n
s
o
l
/
Lo
a
d
(
%
/
p
s
f
)
Dr
y
U
n
i
t
We
i
g
h
t
(
p
c
f
)
Fi
e
l
d
T
e
s
t
Re
s
u
l
t
s
4862 Innovation Dr Ste 104
Hammer Type
Automatic; Hammer
Efficiency = 93%
1
2
4
4842.1
4836
4834
4828.5
4818.7
AGGREGATE BASE COURSE, about 11 inches thick
FILL - LEAN CLAY WITH SAND (CL), brown to gray
with pink
SANDY LEAN CLAY WITH GRAVEL, dark brown, soft
WELL GRADED SAND WITH SILT AND GRAVEL
(SW-SM), medium to coarse grained, yellow brown
with pink, very dense, possible cobbles
CLAYSTONE, yellow brown to gray, medium hard to
very hard, upper 1 to 2 feet is moderately weathered
Boring Terminated at 24.3 Feet
Boring Log No. B-9
Wa
t
e
r
L
e
v
e
l
Ob
s
e
r
v
a
t
i
o
n
s
De
p
t
h
(
F
t
.
)
5
10
15
20
Facilities | Environmental |Geotechnical | Materials
Approximate Elevation: 4843 (Ft.)
Gr
a
p
h
i
c
L
o
g
Mo
d
e
l
L
a
y
e
r
71.9
7.9
17.6
13.1
29.3
9.3
20.2
13.6
16.6
40-19-21
NP
4-11
15/12"
3-3-4
N=7
0-5
5/12"
20-50/5"
17-11-22
N=33
50/4"
50/3"
0.9
7.0
9.0
14.5
24.3
87
117
Advancement Method
4-1/4 inch inside-diameter, continuous-flight,
hollow-stem augers
Notes
Water Level Observations
3.2 feet at completion of drilling
9 feet while drilling
See Exploration and Testing Procedures for a description of field and laboratory proceduresused and additional data (If any).
See Supporting Information for explanation of symbols and abbreviations.
Elevation Reference: Elevation interpolated from a topographic site plan provided by TB Group.
Classification of rock estimated from disturbed samples. Core samples and petrographicanalysis may reveal other rock types.
Harmony Lakes - New Convenience Store
4315 E. Harmony Road | Fort Collins, Colorado
Terracon Project No. 20255045 Fort Collins, CO
Drill Rig
CME 55
Driller
Terracon
Logged by
A. Ellis
Boring Started
09-04-2025
Boring Completed
09-04-2025
Abandonment Method
Boring backfilled with auger cuttings upon
completion.
Sa
m
p
l
e
T
y
p
e
Hammer Type
Automatic; Hammer
Efficiency = 93%
Pe
r
c
e
n
t
Fi
n
e
s
Wa
t
e
r
Co
n
t
e
n
t
(
%
)
Atterberg
Limits
LL-PL-PI
See Exploration PlanLocation:
Latitude: 40.5213° Longitude: -104.9946°
Depth (Ft.)
Sw
e
l
l
-
C
o
n
s
o
l
/
Lo
a
d
(
%
/
p
s
f
)
Dr
y
U
n
i
t
We
i
g
h
t
(
p
c
f
)
Fi
e
l
d
T
e
s
t
Re
s
u
l
t
s
4862 Innovation Dr Ste 104
1
2
3
4
5
4835
4828
4817.9
FILL - LEAN CLAY WITH SAND, trace gravel, dark
brown, organics at about 2 feet
CLAYEY SAND (SC), trace gravel, dark brown, very
loose to loose
CLAYSTONE, gray, medium hard to very hard
Boring Terminated at 24.1 Feet
Boring Log No. B-10
Wa
t
e
r
L
e
v
e
l
Ob
s
e
r
v
a
t
i
o
n
s
De
p
t
h
(
F
t
.
)
5
10
15
20
Facilities | Environmental |Geotechnical | Materials
Approximate Elevation: 4842 (Ft.)
Gr
a
p
h
i
c
L
o
g
Mo
d
e
l
L
a
y
e
r
35.1
16.1
16.6
20.8
17.5
14.1
13.0
7.7
30-18-12
7.0
14.0
24.1
+2.2/
1000 119
2-4-4
N=8
2-3
5/12"
0-0-0
N=0
1-2-2
N=4
20-32
52/12"
27-50/4"
50/1"
Advancement Method
4-1/4 inch inside-diameter, continuous-flight,
hollow-stem augers
Notes
Water Level Observations
2.2 feet after about 24 hours
Not encountered at completion of drilling
Not encountered while drilling
See Exploration and Testing Procedures for a description of field and laboratory proceduresused and additional data (If any).
See Supporting Information for explanation of symbols and abbreviations.
Elevation Reference: Elevation interpolated from a topographic site plan provided by TB Group.
Classification of rock estimated from disturbed samples. Core samples and petrographicanalysis may reveal other rock types.
Harmony Lakes - New Convenience Store
4315 E. Harmony Road | Fort Collins, Colorado
Terracon Project No. 20255045 Fort Collins, CO
Drill Rig
CME 55
Driller
Terracon
Logged by
A. Ellis
Boring Started
09-03-2025
Boring Completed
09-03-2025
Abandonment Method
Boring backfilled with auger cuttings upon
completion.
Sa
m
p
l
e
T
y
p
e
Hammer Type
Automatic; Hammer
Efficiency = 93%
Pe
r
c
e
n
t
Fi
n
e
s
Wa
t
e
r
Co
n
t
e
n
t
(
%
)
Atterberg
Limits
LL-PL-PI
See Exploration PlanLocation:
Latitude: 40.5223° Longitude: -104.9946°
Depth (Ft.)
Sw
e
l
l
-
C
o
n
s
o
l
/
Lo
a
d
(
%
/
p
s
f
)
Dr
y
U
n
i
t
We
i
g
h
t
(
p
c
f
)
Fi
e
l
d
T
e
s
t
Re
s
u
l
t
s
4862 Innovation Dr Ste 104
2
4
5
4847
4841
4834
4826
4823.7
AGGREGATE SURFACING, about 12 inches thick
FILL - SANDY LEAN CLAY WITH GRAVEL, brown
CLAYEY SAND, dark brown, very loose
WELL GRADED SAND WITH GRAVEL, light brown
with pink, dense to very dense, possible cobbles
CLAYSTONE, gray, very hard
Boring Terminated at 24.3 Feet
Boring Log No. B-11
Wa
t
e
r
L
e
v
e
l
Ob
s
e
r
v
a
t
i
o
n
s
De
p
t
h
(
F
t
.
)
5
10
15
20
Facilities | Environmental |Geotechnical | Materials
Approximate Elevation: 4848 (Ft.)
Gr
a
p
h
i
c
L
o
g
Mo
d
e
l
L
a
y
e
r
7.5
15.6
18.5
27.1
8.1
10.1
13.6
1.0
7.0
14.0
22.0
24.3
113
117
5-10
15/12"
3-6-9
N=15
2-2
4/12"
0-0-2
N=2
7-16-26
N=42
8-20-42
N=62
50/3"
Advancement Method
4-1/4 inch inside-diameter, continuous-flight,
hollow-stem augers
Notes
Water Level Observations
9 feet at completion of drilling
14 feet while drilling
See Exploration and Testing Procedures for a description of field and laboratory proceduresused and additional data (If any).
See Supporting Information for explanation of symbols and abbreviations.
Elevation Reference: Elevation interpolated from a topographic site plan provided by TB Group.
Classification of rock estimated from disturbed samples. Core samples and petrographicanalysis may reveal other rock types.
Harmony Lakes - New Convenience Store
4315 E. Harmony Road | Fort Collins, Colorado
Terracon Project No. 20255045 Fort Collins, CO
Drill Rig
CME 55
Hammer Type
Automatic; Hammer
Efficiency = 93%
Driller
Terracon
Logged by
A. Ellis
Boring Started
09-04-2025
Boring Completed
09-04-2025
Abandonment Method
Boring backfilled with auger cuttings upon
completion.
Sa
m
p
l
e
T
y
p
e
Pe
r
c
e
n
t
Fi
n
e
s
Wa
t
e
r
Co
n
t
e
n
t
(
%
)
Atterberg
Limits
LL-PL-PI
See Exploration PlanLocation:
Latitude: 40.5221° Longitude: -104.9971°
Depth (Ft.)
Sw
e
l
l
-
C
o
n
s
o
l
/
Lo
a
d
(
%
/
p
s
f
)
Dr
y
U
n
i
t
We
i
g
h
t
(
p
c
f
)
Fi
e
l
d
T
e
s
t
Re
s
u
l
t
s
4862 Innovation Dr Ste 104
1
2
4
5
4844
4841
4838
4826
4810.7
AGGREGATE SURFACING, about 12 inches thick
FILL - LEAN CLAY WITH SAND AND GRAVEL, dark
brown
POORLY GRADED SAND, trace gravel, medium
grained, light brown with pink, medium dense
POORLY GRADED SAND WITH SILT AND GRAVEL
(SP-SM), light brown with pink and dark brown,
dense
CLAYSTONE, gray, very hard
Boring Terminated at 34.3 Feet
Boring Log No. B-12
Wa
t
e
r
L
e
v
e
l
Ob
s
e
r
v
a
t
i
o
n
s
De
p
t
h
(
F
t
.
)
5
10
15
20
25
30
Facilities | Environmental |Geotechnical | Materials
Approximate Elevation: 4845 (Ft.)
Gr
a
p
h
i
c
L
o
g
Mo
d
e
l
L
a
y
e
r
6.7
10.1
9.3
8.8
8.5
11.5
16.3
13.4
15.2
18.4
NP
1.0
4.0
7.0
19.0
34.3
121
112
11-13
24/12"
5-5-8
N=13
16-19-17
N=36
13-19-29
N=48
5-20-25
N=45
22-50/4"
50/4"
50/3"
50/3"
Advancement Method
4-1/4 inch inside-diameter, continuous-flight,
hollow-stem augers
Notes
Water Level Observations
3.7 feet after about 24 hours
9.5 feet at completion of drilling
7 feet while drilling
See Exploration and Testing Procedures for a description of field and laboratory proceduresused and additional data (If any).
See Supporting Information for explanation of symbols and abbreviations.
Elevation Reference: Elevation interpolated from a topographic site plan provided by TB Group.
Classification of rock estimated from disturbed samples. Core samples and petrographicanalysis may reveal other rock types.
Harmony Lakes - New Convenience Store
4315 E. Harmony Road | Fort Collins, Colorado
Terracon Project No. 20255045 Fort Collins, CO
Drill Rig
CME 55
Driller
Terracon
Logged by
A. Ellis
Boring Started
09-03-2025
Boring Completed
09-03-2025
Abandonment Method
Boring backfilled with auger cuttings upon
completion.
Sa
m
p
l
e
T
y
p
e
Pe
r
c
e
n
t
Fi
n
e
s
Wa
t
e
r
Co
n
t
e
n
t
(
%
)
Atterberg
Limits
LL-PL-PI
See Exploration PlanLocation:
Latitude: 40.5214° Longitude: -104.9965°
Depth (Ft.)
Sw
e
l
l
-
C
o
n
s
o
l
/
Lo
a
d
(
%
/
p
s
f
)
Dr
y
U
n
i
t
We
i
g
h
t
(
p
c
f
)
Fi
e
l
d
T
e
s
t
Re
s
u
l
t
s
4862 Innovation Dr Ste 104
Hammer Type
Automatic; Hammer
Efficiency = 93%
1
2
4
5
0
10
20
30
40
50
60
0 10 20 30 40 50 60 70 80 90 100 110
"A" Line
ASTM D4318
CH or OH
CL or OL
ML or OL
MH or OH
13
11
3
25
NP
8
15
21
NP
12
NP
54.3
51.0
21.3
68.6
7.6
16.6
37.0
71.9
7.9
35.1
6.7
CL
CL
SM
CL
SP-SM
SC
SC
CL
SW-SM
SC
SP-SM
15
20
15
18
NP
13
14
19
NP
18
NP
13
11
3
25
NP
8
15
21
NP
12
NP
54.3
51.0
21.3
68.6
7.6
16.6
37.0
71.9
7.9
35.1
6.7
CL
CL
SM
CL
SP-SM
SC
SC
CL
SW-SM
SC
SP-SM
15
20
15
18
NP
13
14
19
NP
18
NP
28
31
18
43
NP
21
29
40
NP
30
NP
SANDY LEAN CLAY
SANDY LEAN CLAY with GRAVEL
SILTY SAND with GRAVEL
SANDY LEAN CLAY
POORLY GRADED SAND with SILT and GRAVEL
CLAYEY SAND with GRAVEL
CLAYEY SAND with GRAVEL
LEAN CLAY with SAND
WELL-GRADED SAND with SILT and GRAVEL
CLAYEY SAND
POORLY GRADED SAND with SILT and GRAVEL
Atterberg Limit Results
"U" Line
Liquid Limit
LL PL PI Fines USCS DescriptionFines
Pl
a
s
t
i
c
i
t
y
I
n
d
e
x
CL - ML
16
4
7
Facilities | Environmental |Geotechnical | Materials
2 - 3.5
9 - 10
4 - 5.5
4 - 5.5
14 - 14.9
1 - 5
1 - 5
2 - 3
9 - 9.9
9 - 10.5
7 - 8.5
B-1
B-2
B-3
B-4
B-5
B-6
B-7
B-9
B-9
B-10
B-12
Boring ID Depth (Ft)
Fort Collins, COTerracon Project No. 20255045
4315 E. Harmony Road | Fort Collins, Colorado
Harmony Lakes - New Convenience Store
4862 Innovation Dr Ste 104
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
0.0010.010.1110100
140
HydrometerU.S. Sieve Opening in Inches
Grain Size Distribution
ASTM D422 / ASTM C136
SandGravel
2 10 14 506 2001.5 83/4 1/23/8 30 403 601
U.S. Sieve Numbers
16 2044 10063
Grain Size (mm)
coarse fine coarse finemedium Silt or ClayCobbles
Pe
r
c
e
n
t
C
o
a
r
s
e
r
b
y
W
e
i
g
h
t
Pe
r
c
e
n
t
F
i
n
e
r
b
y
W
e
i
g
h
t
100
90
80
70
60
50
40
30
20
10
0
AASHTOUSCSUSCS Classification
A-6 (4)
A-6 (3)
A-1-b (0)
A-7-6 (15)
A-1-a (0)
CL
CL
SM
CL
SP-SM
SANDY LEAN CLAY
SANDY LEAN CLAY with GRAVEL
SILTY SAND with GRAVEL
SANDY LEAN CLAY
POORLY GRADED SAND with SILT and
GRAVEL
Facilities | Environmental |Geotechnical | Materials
28
31
18
43
NP 0.80
13
11
3
25
NP
15
20
15
18
NP
%CobblesD60
0.093
0.103
0.761
5.277
D100
45.54
%Clay%Sand%Gravel
11.7
19.8
17.6
0.8
41.7
34.0
29.3
61.1
30.6
50.7
54.3
51.0
21.3
68.6
7.6
LL PL PI Cc Cu
0.0
0.0
0.0
0.0
0.0
D10
0.116
D30
0.15
0.701
25
37.5
19
9.5
25
%Fines %Silt
Fort Collins, COTerracon Project No. 20255045
4315 E. Harmony Road | Fort Collins, Colorado
Harmony Lakes - New Convenience Store
Boring ID
2 - 3.5
9 - 10
4 - 5.5
4 - 5.5
14 - 14.9
B-1
B-2
B-3
B-4
B-5
2 - 3.5
9 - 10
4 - 5.5
4 - 5.5
14 - 14.9
Depth (Ft)Boring ID
B-1
B-2
B-3
B-4
B-5
Depth (Ft)
4862 Innovation Dr Ste 104
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
0.0010.010.1110100
140
HydrometerU.S. Sieve Opening in Inches
Grain Size Distribution
ASTM D422 / ASTM C136
SandGravel
2 10 14 506 2001.5 83/4 1/23/8 30 403 601
U.S. Sieve Numbers
16 2044 10063
Grain Size (mm)
coarse fine coarse finemedium Silt or ClayCobbles
Pe
r
c
e
n
t
C
o
a
r
s
e
r
b
y
W
e
i
g
h
t
Pe
r
c
e
n
t
F
i
n
e
r
b
y
W
e
i
g
h
t
100
90
80
70
60
50
40
30
20
10
0
AASHTOUSCSUSCS Classification
A-2-4 (0)
A-6 (1)
A-6 (14)
A-1-a (0)
A-2-6 (0)
SC
SC
CL
SW-SM
SC
CLAYEY SAND with GRAVEL
CLAYEY SAND with GRAVEL
LEAN CLAY with SAND
WELL-GRADED SAND with SILT and
GRAVELCLAYEY SAND
Facilities | Environmental |Geotechnical | Materials
21
29
40
NP
30
1.11
8
15
21
NP
12
13
14
19
NP
18
%CobblesD60
4.255
0.55
5.233
0.427
D100
41.89
%Clay%Sand%Gravel
38.4
18.8
1.2
41.9
13.4
45.0
44.2
26.9
50.2
51.4
16.6
37.0
71.9
7.9
35.1
LL PL PI Cc Cu
0.0
0.0
0.0
0.0
0.0
D10
0.125
D30
0.395
0.854
19
37.5
9.5
37.5
25
%Fines %Silt
Fort Collins, COTerracon Project No. 20255045
4315 E. Harmony Road | Fort Collins, Colorado
Harmony Lakes - New Convenience Store
Boring ID
1 - 5
1 - 5
2 - 3
9 - 9.9
9 - 10.5
B-6
B-7
B-9
B-9
B-10
1 - 5
1 - 5
2 - 3
9 - 9.9
9 - 10.5
Depth (Ft)Boring ID
B-6
B-7
B-9
B-9
B-10
Depth (Ft)
4862 Innovation Dr Ste 104
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
0.0010.010.1110100
140
HydrometerU.S. Sieve Opening in Inches
Grain Size Distribution
ASTM D422 / ASTM C136
SandGravel
2 10 14 506 2001.5 83/4 1/23/8 30 403 601
U.S. Sieve Numbers
16 2044 10063
Grain Size (mm)
coarse fine coarse finemedium Silt or ClayCobbles
Pe
r
c
e
n
t
C
o
a
r
s
e
r
b
y
W
e
i
g
h
t
Pe
r
c
e
n
t
F
i
n
e
r
b
y
W
e
i
g
h
t
100
90
80
70
60
50
40
30
20
10
0
AASHTOUSCSUSCS Classification
A-1-a (0)SP-SMPOORLY GRADED SAND with SILT and
GRAVEL
Facilities | Environmental |Geotechnical | Materials
NP 0.97NPNP
%CobblesD60
5.74
D100
43.30
%Clay%Sand%Gravel
44.2 49.1 6.7
LL PL PI Cc Cu
0.0
D10
0.133
D30
0.86125
%Fines %Silt
Fort Collins, COTerracon Project No. 20255045
4315 E. Harmony Road | Fort Collins, Colorado
Harmony Lakes - New Convenience Store
Boring ID
7 - 8.5B-12
7 - 8.5
Depth (Ft)Boring ID
B-12
Depth (Ft)
4862 Innovation Dr Ste 104
-6
-5
-4
-3
-2
-1
0
1
2
3
4
100 1,000 10,000
Ax
i
a
l
S
t
r
a
i
n
(
%
)
Pressure (psf)
One-Dimensional Swell or Collapse
Facilities | Environmental |Geotechnical | Materials
Notes: The sample exhibited less than 0.1 percent swell upon wetting under an applied pressure of 500 psf.
12.3115
(pcf) WC (%)Description USCS
FILL - SANDY LEAN CLAY
Fort Collins, COTerracon Project No. 20255045
4315 E. Harmony Road | Fort Collins, Colorado
Harmony Lakes - New Convenience Store
Boring ID Depth (Ft)
4 - 5B-1
4862 Innovation Dr Ste 104
-6
-5
-4
-3
-2
-1
0
1
2
3
4
100 1,000 10,000
Ax
i
a
l
S
t
r
a
i
n
(
%
)
Pressure (psf)
One-Dimensional Swell or Collapse
Facilities | Environmental |Geotechnical | Materials
Notes: The sample exhibited less than 0.1 percent compression upon wetting under an applied pressure of 1,000 psf.
29.093
(pcf) WC (%)Description USCS
LEAN CLAY
Fort Collins, COTerracon Project No. 20255045
4315 E. Harmony Road | Fort Collins, Colorado
Harmony Lakes - New Convenience Store
Boring ID Depth (Ft)
9 - 10B-1
4862 Innovation Dr Ste 104
-6
-5
-4
-3
-2
-1
0
1
2
3
4
100 1,000 10,000
Ax
i
a
l
S
t
r
a
i
n
(
%
)
Pressure (psf)
One-Dimensional Swell or Collapse
Facilities | Environmental |Geotechnical | Materials
Notes: The sample exhibited 0.2 percent swell upon wetting under an applied pressure of 500 psf.
14.8115
(pcf) WC (%)Description USCS
LEAN CLAY
Fort Collins, COTerracon Project No. 20255045
4315 E. Harmony Road | Fort Collins, Colorado
Harmony Lakes - New Convenience Store
Boring ID Depth (Ft)
4 - 5B-2
4862 Innovation Dr Ste 104
-6
-5
-4
-3
-2
-1
0
1
2
3
4
100 1,000 10,000
Ax
i
a
l
S
t
r
a
i
n
(
%
)
Pressure (psf)
One-Dimensional Swell or Collapse
Facilities | Environmental |Geotechnical | Materials
Notes: The sample exhibited less than 0.1 percent swell upon wetting under an applied pressure of 150 psf.
15.5113
(pcf) WC (%)Description USCS
LEAN CLAY WITH SAND
Fort Collins, COTerracon Project No. 20255045
4315 E. Harmony Road | Fort Collins, Colorado
Harmony Lakes - New Convenience Store
Boring ID Depth (Ft)
2 - 3B-3
4862 Innovation Dr Ste 104
-6
-5
-4
-3
-2
-1
0
1
2
3
4
100 1,000 10,000
Ax
i
a
l
S
t
r
a
i
n
(
%
)
Pressure (psf)
One-Dimensional Swell or Collapse
Facilities | Environmental |Geotechnical | Materials
Notes: The sample exhibited 0.2 percent swell upon wetting under an applied pressure of 500 psf.
16.8112
(pcf) WC (%)Description USCS
FILL - SANDY LEAN CLAY
Fort Collins, COTerracon Project No. 20255045
4315 E. Harmony Road | Fort Collins, Colorado
Harmony Lakes - New Convenience Store
Boring ID Depth (Ft)
2 - 3B-4
4862 Innovation Dr Ste 104
-6
-5
-4
-3
-2
-1
0
1
2
3
4
100 1,000 10,000
Ax
i
a
l
S
t
r
a
i
n
(
%
)
Pressure (psf)
One-Dimensional Swell or Collapse
Facilities | Environmental |Geotechnical | Materials
Notes: The sample exhibited less than 0.1 percent swell upon wetting under an applied pressure of 150 psf.
3.5126
(pcf) WC (%)Description USCS
FILL - CLAYEY SAND WITH GRAVEL
Fort Collins, COTerracon Project No. 20255045
4315 E. Harmony Road | Fort Collins, Colorado
Harmony Lakes - New Convenience Store
Boring ID Depth (Ft)
2 - 3B-6
4862 Innovation Dr Ste 104
-6
-5
-4
-3
-2
-1
0
1
2
3
4
100 1,000 10,000
Ax
i
a
l
S
t
r
a
i
n
(
%
)
Pressure (psf)
One-Dimensional Swell or Collapse
Facilities | Environmental |Geotechnical | Materials
Notes: The sample exhibited 0.2 percent compression upon wetting under an applied pressure of 500 psf.
11.2122
(pcf) WC (%)Description USCS
FILL - CLAYEY SAND WITH GRAVEL
Fort Collins, COTerracon Project No. 20255045
4315 E. Harmony Road | Fort Collins, Colorado
Harmony Lakes - New Convenience Store
Boring ID Depth (Ft)
4 - 5B-6
4862 Innovation Dr Ste 104
-6
-5
-4
-3
-2
-1
0
1
2
3
4
100 1,000 10,000
Ax
i
a
l
S
t
r
a
i
n
(
%
)
Pressure (psf)
One-Dimensional Swell or Collapse
Facilities | Environmental |Geotechnical | Materials
Notes: The sample exhibited 0.5 percent swell upon wetting under an applied pressure of 150 psf.
43.194
(pcf) WC (%)Description USCS
FILL - CLAYEY SAND WITH GRAVEL
Fort Collins, COTerracon Project No. 20255045
4315 E. Harmony Road | Fort Collins, Colorado
Harmony Lakes - New Convenience Store
Boring ID Depth (Ft)
2 - 3B-7
4862 Innovation Dr Ste 104
-6
-5
-4
-3
-2
-1
0
1
2
3
4
100 1,000 10,000
Ax
i
a
l
S
t
r
a
i
n
(
%
)
Pressure (psf)
One-Dimensional Swell or Collapse
Facilities | Environmental |Geotechnical | Materials
Notes: The sample exhibited 0.4 percent swell upon wetting under an applied pressure of 500 psf.
16.6114
(pcf) WC (%)Description USCS
LEAN CLAY WITH SAND
Fort Collins, COTerracon Project No. 20255045
4315 E. Harmony Road | Fort Collins, Colorado
Harmony Lakes - New Convenience Store
Boring ID Depth (Ft)
4 - 5B-7
4862 Innovation Dr Ste 104
-6
-5
-4
-3
-2
-1
0
1
2
3
4
100 1,000 10,000
Ax
i
a
l
S
t
r
a
i
n
(
%
)
Pressure (psf)
One-Dimensional Swell or Collapse
Facilities | Environmental |Geotechnical | Materials
Notes: The sample exhibited 2.2 percent swell upon wetting under an applied pressure of 1,000 psf.
14.1119
(pcf) WC (%)Description USCS
CLAYSTONE
Fort Collins, COTerracon Project No. 20255045
4315 E. Harmony Road | Fort Collins, Colorado
Harmony Lakes - New Convenience Store
Boring ID Depth (Ft)
14 - 15B-10
4862 Innovation Dr Ste 104
4862 Innovation Drive, Suite 104
Fort Collins, Colorado 80525
(970) 484-0359 FAX (970) 484-0454
CLIENT:Big D Oil Company DATE OF TEST:23-Sep-25
PROJECT:Harmony Lakes - New Convenience Store
LOCATION:B-7 at 1.0-5.0
TERRACON NO.20255045 CLASSIFICATION:Clayey Sand with Gravel (SC)
TEST SPECIMEN NO.1 2 3
COMPACTION PRESSURE (PSI)100 150 250
DENSITY (PCF)133.8 135.9 130.0
MOISTURE CONTENT (%)10.2 9.6 7.1
EXPANSION PRESSURE (PSI)0.00 0.00 0.00
HORIZONTAL PRESSURE @ 160 PSI 110 98 42
SAMPLE HEIGHT (INCHES)2.51 2.50 2.53
EXUDATION PRESSURE (PSI)160.3 212.8 500.3
CORRECTED R-VALUE 25.1 32.4 69.2
UNCORRECTED R-VALUE 25.1 32.4 69.2
R-VALUE @ 300 PSI EXUDATION PRESSURE =44
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-
V
A
L
U
E
EXUDATION PRESSURE - PSI
Client
B-1 B-4 B-10
1.0-5.0 1.0-5.0 1.0-5.0
405 378 228
Analyzed By:
Project
Big D Oil Company Harmony Lakes - New Convenience Store
Rapid City, SD 20255045
Date Received:9/9/2025
(mg/kg)
Results from Corrosion Testing
Sample Location
Sample Depth (ft.)
The tests were performed in general accordance with applicable ASTM and AASHTO 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.
Chloe Lewis
Laboratory Supervisor
Client
9/22/2025
B-2 B-8
1'-5'1'-5'
AASHTO T289 8.47 8.5
ASTM C1580 121 120
AWWA 4500-S,D Nil Nil
ASTM D512 61 16
ASTM G200 234 244
AWWA 2520 B 935 466
ASTM G57 1500 4200
These tests were performed in general accordance with the applicable AASHTO, ASTM, and AWWA test methods. This report is exclusively
for the use of the client indicated above and shall not be reproduced without the full written consent of Terracon Consultants Inc.. 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 materials.
Kyle Lemcke
9/25/2025
Verified By:
Acidity (pH)
Water Soluble Sulfate
Ion Content (mg/Kg)
Water Soluble Sulfide
Content (mg/Kg)
Water Soluble Chloride
Ion Content (mg/Kg)
Corrosivity Suite -Results
Sample Location
Project
Big D Oil Company Big D Oil Harmony Lakes
Rapid City, SD 20250545
Date Received:
Sample Depth (ft.)
Oxidation-Reduction
Potential (RmV)
Total Dissolved Salts
(mg/Kg)
Electrical Resistivity
(Ω·cm)
Harmony Lakes - New Convenience Store
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
October 22, 2025 | Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials
Supporting Information
Contents:
General Notes
Unified Soil Classification System
Note: All attachments are one page unless noted above.
Auger
Cuttings
Modified
California
Ring
Sampler
Standard
Penetration
Test
Facilities | Environmental |Geotechnical | Materials
Unconfined
Compressive
Strength
Qu (psf)
1,000 to 2,000
2,000 to 4,000
4,000 to 8,000
> 8,000
less than 500
500 to 1,000
Harmony Lakes - New Convenience Store
4315 E. Harmony Road | Fort Collins, Colorado
Terracon Project No. 20255045
4862 Innovation Dr Ste 104
Fort Collins, CO
N
(HP)
(T)
(DCP)
UC
(PID)
(OVA)
Standard Penetration Test
Resistance (Blows/Ft.)
Hand Penetrometer
Torvane
Dynamic Cone Penetrometer
Unconfined Compressive
Strength
Photo-Ionization Detector
Organic Vapor Analyzer
Water Level After a
Specified Period of Time
Water Level After
a Specified Period of Time
Cave In
Encountered
Water Level Field Tests
Water Initially
Encountered
Sampling
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.
General Notes
Location And Elevation Notes
Exploration point locations as shown on the Exploration Plan and as noted on the soil boring logs in the form of Latitude and Longitude are
approximate. See Exploration and Testing Procedures in the report for the methods used to locate the exploration points for this project. Surface
elevation data annotated with +/- indicates that no actual topographical survey was conducted to confirm the surface elevation. Instead, the surface
elevation was approximately determined from topographic maps of the area.
Soil classification as noted on the soil boring logs is based Unified Soil Classification System. Where sufficient laboratory data exist to classify the soils
consistent with ASTM D2487 "Classification of Soils for Engineering Purposes" this procedure is used. ASTM D2488 "Description and Identification of
Soils (Visual-Manual Procedure)" is also used to classify the soils, particularly where insufficient laboratory data exist to classify the soils in accordance
with ASTM D2487. In addition to USCS classification, coarse grained soils are classified on the basis of their in-place relative density, and fine-grained
soils are classified on the basis of their consistency. See "Strength Terms" table below for details. The ASTM standards noted above are for reference
to methodology in general. In some cases, variations to methods are applied as a result of local practice or professional judgment.
Exploration/field results and/or laboratory test data contained within this document are intended for application to the project as described in this
document. Use of such exploration/field results and/or laboratory test data should not be used independently of this document.
Relevance of Exploration and Laboratory Test Results
Descriptive Soil Classification
> 30
15 - 30
8 - 15
4 - 8
2 - 4
0 - 1
Very Stiff
Consistency of Fine-Grained Soils Bedrock
(More than 50% retained on No. 200 sieve.)
Density determined by Standard Penetration
Resistance
Relative Density of Coarse-Grained Soils
< 3
Consistency
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
6- 10
11 - 18
19 - 36
> 36
Standard
Penetration
or N-Value
(Blows/Ft.)
Ring
Sampler
(Blows/Ft.)
Relative Density
Very Loose
Loose
Standard
Penetration
or N-Value
(Blows/Ft.)
> 50
30 - 50
10 - 29
4 - 9
Ring
Sampler
(Blows/Ft.)
Hard
Medium Dense
Dense
Very Dense
0 - 5
6 - 14
> 80
Firm
_
47 - 79
Medium Hard
Hard
Very Hard
Ring
Sampler
(Blows/Ft.)
< 24
24 - 35
36 - 60
61 - 96
>79
15 - 46
0 - 3
3 - 5
Consistency
Standard
Penetration or
N-Value
(Blows/Ft.)
< 20
20 - 29
30 - 49
50 - 79
> 96
Soft
Geotechnical Engineering Report
Harmony Lakes – Public Improvements | Fort Collins, Colorado
Terracon Project No. 20255045
Facilities | Environmental | Geotechnical | Materials
Unified Soil Classification System
Criteria for Assigning Group Symbols and Group Names Using
Laboratory Tests A
Soil Classification
Group
Symbol Group Name B
Coarse-Grained Soils:
Gravels: Clean Gravels:
C
≥4 and 1≤Cc≤3 E F
E F
Gravels with Fines:
C
F, G, H
F, G, H
Sands: Clean Sands:
D
≥6 and 1≤Cc≤3 E I
E I
Sands with Fines:
D
G, H, I
G, H, I
Fine-Grained Soils:
Silts and Clays: Inorganic: 7 and plots above “A” line J K, L, M
4 or plots below “A” line J K, L, M
Organic: 𝐿𝐿 𝑜𝑣𝑒𝑛 𝑑𝑟𝑖𝑒𝑑
𝐿𝐿 𝑛𝑜𝑡 𝑑𝑟𝑖𝑒𝑑<0.75
K, L, M, N
K, L, M, O
Silts and Clays: Inorganic: PI plots on or above “A” line K, L, M
PI plots below “A” line K, L, M
Organic: 𝐿𝐿 𝑜𝑣𝑒𝑛 𝑑𝑟𝑖𝑒𝑑
𝐿𝐿 𝑛𝑜𝑡 𝑑𝑟𝑖𝑒𝑑<0.75
K, L, M, P
K, L, M, Q
Highly organic soils:
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 = D 60/D 10 Cc =
F If soil contains ≥ 15% sand, add “with sand” to group name.
G If fines classify as CL -ML, use dual symbol GC -GM, or SC -SM.
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.
6010
2
30
DxD
)(D