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Geotechnical Engineering Report
__________________________________________________________________________
Beta Tau Fraternity House Addition
Fort Collins, Colorado
August 5, 2020
Terracon Project No. 20205071
Prepared for:
Beta Tau 1919 Corporation
Denver, Colorado
Prepared by:
Terracon Consultants, Inc.
Fort Collins, Colorado
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REPORT TOPICS
INTRODUCTION ............................................................................................................. 1
SITE CONDITIONS ......................................................................................................... 1
PROJECT DESCRIPTION .............................................................................................. 2
GEOTECHNICAL CHARACTERIZATION ...................................................................... 3
GEOTECHNICAL OVERVIEW ....................................................................................... 4
EARTHWORK................................................................................................................. 5
SHALLOW FOUNDATIONS ......................................................................................... 11
SEISMIC CONSIDERATIONS ...................................................................................... 14
FLOOR SYSTEM .......................................................................................................... 14
BELOW-GRADE STRUCTURES ................................................................................. 16
PAVEMENTS ................................................................................................................ 17
CORROSIVITY.............................................................................................................. 20
GENERAL COMMENTS ............................................................................................... 20
Note: This report was originally delivered in a web-based format. Orange Bold text in the report indicates a referenced
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ATTACHMENTS
EXPLORATION AND TESTING PROCEDURES
PHOTOGRAPHY LOG
SITE LOCATION AND EXPLORATION PLANS
EXPLORATION RESULTS
SUPPORTING INFORMATION
Note: Refer to each individual Attachment for a listing of contents.
Geotechnical Engineering Report
Beta Tau Fraternity House Addition ■ Fort Collins, Colorado
August 5, 2020 ■ Terracon Project No. 20205071
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REPORT SUMMARY
Topic
1
Overview Statement
2
Project
Overview
A geotechnical exploration has been performed for the proposed Beta Tau Fraternity
House Addition to be constructed at 1516 Remington Street in Fort Collins, Colorado.
Two (2) borings were performed to depths of approximately 10 to 25½ feet below
existing site grades.
Subsurface
Conditions
Subsurface conditions encountered in our exploratory borings generally consisted of
about 24½ feet of sandy lean clay over claystone bedrock. Claystone bedrock was
encountered below the overburden soils in one of the borings at depth of approximately
24½ feet below existing site grades. Boring logs are presented in the Exploration
Results section of this report.
Groundwater
Conditions
Groundwater was not encountered in any of our test borings at the time of drilling.
Groundwater levels can fluctuate in response to site development and to varying
seasonal and weather conditions, irrigation on or adjacent to the site and fluctuations
in nearby water features.
Geotechnical
Concerns
■ Expansive clays and bedrock are present on this site. This report provides
recommendations to help mitigate the effects of soil movement/heave associated
with these materials. The risk can be mitigated by careful design, construction and
maintenance practices; however, it should be recognized these procedures will not
eliminate risk. The owner should be aware and understand that on-grade slabs,
pavements and, in some instance’s foundations, may be affected to some degree
by the expansive soils and bedrock on this site.
■ Although existing fill was not encountered in our soil borings, existing undocumented
fill is likely associated with the existing building. Undocumented fill can present a
greater than normal risk of post-construction movement of foundations, slabs,
pavements and other site improvements supported on or above these materials.
Any undocumented existing fill encountered during construction of the building
addition should not be relied upon for support and should be removed down to native
soil, moisture conditioned and recompacted prior to new fill placement and/or
construction of foundations and floor slabs. On-site soils are suitable to be used as
engineered fill.
Earthwork
On-site soils typically appear suitable for use as general engineered fill and backfill on
the site provided they are placed and compacted as described in this report. Import
materials (if needed) should be evaluated and approved by Terracon prior to delivery
to the site. Earthwork recommendations are presented in the Earthwork section of
this report.
Grading and
Drainage
The amount of movement of foundations, floor slabs, pavements, etc. will be related to
the wetting of underlying supporting soils. Therefore, it is imperative the
recommendations discussed in the Grading and Drainage section of the Earthwork
section this report be followed to reduce potential movement. As discussed in the
Grading and Drainage section of this report, surface drainage should be designed,
constructed and maintained to provide rapid removal of surface water runoff away from
Geotechnical Engineering Report
Beta Tau Fraternity House Addition ■ Fort Collins, Colorado
August 5, 2020 ■ Terracon Project No. 20205071
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Topic
1
Overview Statement
2
Foundations
Our past experience with the Beta Tau Fraternity house indicates the existing
building is supported on a conventual spread footing shallow foundation system. To
maintain consistent foundation types and performance and to mitigate the impact of
differential movement between the existing building and the planned addition, we
recommend the new building addition be supported on spread footings.
Floor Systems
We understand a crawl space is planned for the building addition. If a slab-on-grade is
utilized for the interior floor system for the proposed building addition Terracon should
be contacted for design recommendations. The subgrade soils should be prepared as
presented in the Earthwork section of this report.
Pavements
Recommended Pavement thicknesses for this project include 3½ inches of asphalt
over 6 inches of aggregate base course in light-duty parking areas and 6 inches of
asphalt over 6 inches of aggregate base course in heavy-duty drive lanes and loading
areas. Additional pavement section alternatives and discussion are presented in the
report.
Seismic
Considerations
As presented in the Seismic Considerations section of this report, the International
Building Code, which refers to Section 20 of ASCE 7, indicates the seismic site
classification for this site is D.
Construction
Observation
and Testing
Close monitoring of the construction operations and implementing drainage
recommendations discussed herein will be critical in achieving the intended
foundation, slab and pavement performance. We therefore recommend that Terracon
be retained to monitor this portion of the work.
General
Comments
This section contains important information about the limitations of this geotechnical
engineering report.
1. If the reader is reviewing this report as a pdf, the topics (bold orange font) above can be used to access the
appropriate section of the report by simply clicking on the topic itself.
2. This summary is for convenience only. It should be used in conjunction with the entire report for design
making and design purposes. It should be recognized that specific details were not included or fully
developed in this section, and the report must be read in its entirety for a comprehensive understanding of
the items contained herein.
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INTRODUC TION
Geotechnical Engineering Report
Beta Tau Fraternity House Addition
1516 Remington Street
Fort Collins, Colorado
Terracon Project No. 20205071
August 5, 2020
INTRODUCTION
This report presents the results of our subsurface exploration and geotechnical engineering
services performed for the proposed Beta Tau Fraternity House Addition to be located at 1516
Remington Street in Fort Collins, Colorado. The purpose of these services is to provide
information and geotechnical engineering recommendations relative to:
■ Subsurface soil and rock conditions ■ Foundation design and construction
■ Groundwater conditions ■ Floor system design and construction
■ Site preparation and earthwork ■ Seismic considerations
■ Demolition considerations ■ Lateral earth pressures
■ Excavation considerations ■ Pavement design and construction
The geotechnical engineering scope of services for this project included the advancement of two
(2) test borings to depths ranging from approximately 10 to 25 feet below existing site grades.
Maps showing the site and boring locations are shown in the Site Location and Exploration
Plan sections, respectively. The results of the laboratory testing performed on soil and bedrock
samples obtained from the site during the field exploration are included on the boring logs and as
separate graphs in the Exploration Results section of this report.
SITE CONDITIONS
The following description of site conditions is derived from our site visit in association with the
field exploration and our review of publicly available geologic and topographic maps.
Item Description
Parcel Information
The project site is located at 1516 Remington Street in Fort Collins,
Colorado. The approximate Latitude/Longitude of the center of the site is
40.56817°N/105.07473°W. See Site Location.
Existing
Improvements
The existing building is a 1 to 2-story wood frame building with a slab-on-
grade garage. The foundations are believed to be spread footings with a
basement.
Current Ground
Cover
The current ground cover consists of native grass and weeds, asphalt
parking area and exterior concrete flat work.
Geotechnical Engineering Report
Beta Tau Fraternity House Addition ■ Fort Collins, Colorado
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Item Description
Existing Topography The site is relatively flat.
We also collected photographs at the time of our field exploration program. Representative photos
are provided in our Photography Log.
PROJECT DESCRIPTION
Our final understanding of the project conditions is as follows:
Item Description
Information Provided
Terracon was provided the site location, anticipated boring location and
anticipated building addition construction from Matt Aragon on July 8, 2020.
Project Description
The project includes demolition of a portion of the existing slab-on-grade and
garage, construction of a 2-story building addition and associated parking
alterations to the rear parking area. The existing building is believed to be
supported on a conventional spread footing shallow foundation system.
Proposed
Construction
The project includes a 2-story, wood frame building with a footprint of about
400 square feet per floor. The building is anticipated to include a crawl space.
Maximum Loads
(assumed)
■ Columns: 10 to 20 kips
■ Walls: 1 to 3 kips per linear foot (klf)
Grading/Slopes
We anticipate minor cuts and fills on the order of 5 feet or less will be required
to achieve proposed grades.
Below-grade
Structures
We understand a crawl space is planned for the building addition.
Pavements
We assume both rigid (concrete) and flexible (asphalt) pavement sections
should be considered. Please confirm this assumption.
Anticipated traffic is as follows:
■ Autos/light trucks: 20 vehicles per day
■ Light delivery and trash collection vehicles: 2 vehicles per week
The pavement design period is 20 years.
If project information or assumptions vary from what is described above or if location of
construction changes, we should be contacted as soon as possible to confirm and/or modify our
recommendations accordingly.
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Beta Tau Fraternity House Addition ■ Fort Collins, Colorado
August 5, 2020 ■ Terracon Project No. 20205071
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GEOTECHNICAL CHARACTERIZATION
Subsurface Profile
We have developed a general characterization of the subsurface conditions based upon our
review of the subsurface exploration, laboratory data, geologic setting and our understanding of
the project. This characterization, termed GeoModel, forms the basis of our geotechnical
calculations and evaluation of site preparation and foundation options. Conditions encountered at
each exploration point are indicated on the individual logs. The individual logs can be found in the
Exploration Results section and the GeoModel can be found in the Figures section of this report.
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
Approximate Depth to
Bottom of Stratum
1 Lean Clay
Sandy lean clay, trace gravel, brown to
red brown, medium stiff to very stiff
About 24½ feet below
existing site grades.
2
Claystone
Bedrock
Claystone bedrock, brown to orange,
very weathered, trace FeOx
About 24½ feet below
existing site grades.
As noted in General Comments, this characterization is based upon widely spaced exploration
points across the site and variations are likely.
Groundwater Conditions
Groundwater was not observed in any of the borings while drilling, or for the short duration the borings
could remain open. However, this does not necessarily mean the borings terminated above
groundwater, or the water levels summarized above are stable groundwater levels. Due to the low
permeability of the soils encountered in the borings, a relatively long period may be necessary for a
groundwater level to develop and stabilize in a borehole. Long term observations in piezometers or
observation wells sealed from the influence of surface water are often required to define groundwater
levels in materials of this type.
Laboratory Testing
Representative soil samples were selected for swell-consolidation testing and exhibited no
movement to 1.0 percent swell when wetted. One sample of clay soils exhibited an unconfined
compressive strength of approximately 4,190 pounds per square foot (psf). Samples of site soils
selected for plasticity testing exhibited moderate plasticity with liquid limits ranging from 34 to 35
and plasticity index of 22. Laboratory test results are presented in the Exploration Results
section of this report.
Geotechnical Engineering Report
Beta Tau Fraternity House Addition ■ Fort Collins, Colorado
August 5, 2020 ■ Terracon Project No. 20205071
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GEOTECHNICAL OVERVIEW
Based on subsurface conditions encountered in the borings, the site appears suitable for the
proposed construction from a geotechnical point of view provided certain precautions and design
and construction recommendations described in this report are followed and the owner
understands the inherent risks associated with construction on sites underlain by expansive soils
and bedrock. We have identified several geotechnical conditions that could impact design,
construction and performance of the proposed building addition, pavements, and other site
improvements. These included existing, undocumented fill, expansive soils and bedrock, and
potentially soft. 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
Although existing fill was not encountered in our soil borings, existing undocumented fill is likely
associated with the existing building. Any undocumented existing fill encountered during
construction of the building addition should not be relied upon for support of foundations and floor
slabs and should be removed down to native soil, moisture conditioned and recompacted prior to
new fill placement and/or construction, on-site soils are suitable to be used as engineered fill.
Undocumented fill can present a greater than normal risk of post-construction movement of
foundations, slabs, pavements and other site improvements supported on or above these
materials.
Expansive Soils and Bedrock
Expansive soils and bedrock are present on this site and these conditions constitute a geologic
hazard. However, at the current moisture content and density the soils are considered to have
low swelling potential. This report provides recommendations to help mitigate the effects of soil
shrinkage and expansion. However, even if these procedures are followed, some movement and
cracking in the structures, pavements, and flatwork is possible. The severity of cracking and other
damage such as uneven floor slabs and flat work will probably increase if modification of the site
results in excessive wetting or drying of the expansive clays and/or claystone bedrock.
Eliminating the risk of movement and cosmetic distress is generally not feasible, but it may be
possible to further reduce the risk of movement if significantly more expensive measures are used
during construction. It is imperative the recommendations described in section Grading and
Drainage section of the Earthwork section of this report be followed to reduce potential
movement.
Foundation and Floor System Recommendations
Our past experience with the Beta Tau Fraternity house indicates the existing building is
supported on a conventual spread footing shallow foundation system. To maintain consistent
foundation types and performance and to mitigate the impact of differential movement between
Geotechnical Engineering Report
Beta Tau Fraternity House Addition ■ Fort Collins, Colorado
August 5, 2020 ■ Terracon Project No. 20205071
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the existing building and the planned addition, we recommend the new building addition be
supported on spread footings. Design recommendations for foundations for the proposed
structure and related structural elements are presented in the following paragraphs.
The General Comments section provides an understanding of the report limitations.
EARTHWORK
The following presents recommendations for site preparation, demolition, excavation, subgrade
preparation, fill materials, compaction requirements, utility trench backfill, grading and drainage
and exterior slab design and construction. Earthwork on the project should be observed and
evaluated by Terracon. Evaluation of earthwork should include observation and/or testing of over-
excavation, removal of existing fill (if encountered), subgrade preparation, placement of
engineered fills, subgrade stabilization and other geotechnical conditions exposed during the
construction of the project.
Site Preparation
Prior to placing any fill, strip and remove existing vegetation, topsoil, and any other deleterious
materials from the proposed construction areas. As previously stated, we also recommend
complete removal of existing, undocumented fill within proposed building areas.
Stripped organic materials should be wasted from the site or used to re-vegetate landscaped areas
after completion of grading operations. Prior to the placement of fills, the site should be graded to
create a relatively level surface to receive fill, and to provide for a relatively uniform thickness of fill
beneath proposed structures.
If fill is placed in areas of the site where existing slopes are steeper than 5:1 (horizontal:vertical),
the area should be benched to reduce the potential for slippage between existing slopes and fills.
Benches should be wide enough to accommodate compaction and earth moving equipment, and
to allow placement of horizontal lifts of fill.
Demolition
Demolition of the existing single-story wood frame garage should include complete removal of all
foundation systems, below-grade structural elements, pavements, and exterior flat work within the
proposed construction area. This should include removal of any utilities to be abandoned along
with any loose utility trench backfill or loose backfill found adjacent to existing foundations. All
materials derived from the demolition of existing structures and pavements should be removed from
the site. The types of foundation systems supporting the existing garage is believed to be a slab-
on-grade.
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Beta Tau Fraternity House Addition ■ Fort Collins, Colorado
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Consideration could be given to re-using the asphalt and concrete provided the materials are
processed and uniformly blended with the on-site soils. Asphalt and/or concrete materials should
be processed to a maximum size of 2 inches and blended at a ratio of 30 percent asphalt/concrete
to 70 percent of on-site soils.
Excavation
It is anticipated that excavations for the proposed construction can be accomplished with
conventional earthmoving equipment.
The soils to be excavated can vary significantly across the site as their classifications are based
solely on the materials encountered in widely-spaced exploratory test borings. The contractor
should verify that similar conditions exist throughout the proposed area of excavation. If different
subsurface conditions are encountered at the time of construction, the actual conditions should be
evaluated to determine any excavation modifications necessary to maintain safe conditions.
Although evidence of fills or underground facilities such as grease pits, septic tanks, vaults,
basements, and utilities was not observed during the site reconnaissance, such features could be
encountered during construction. If unexpected underground facilities are encountered, such
features should be removed, and the excavation thoroughly cleaned prior to backfill placement
and/or construction.
Any over-excavation that extends below the bottom of foundation elevation should extend laterally
beyond all edges of the foundations at least 8 inches per foot of over-excavation depth below the
foundation base elevation. The over-excavation should be backfilled to the foundation base
elevation in accordance with the recommendations presented in this report.
Any existing building foundations that are exposed during the excavation of the existing fill (if any)
or for the new foundation excavations should be examined and evaluated by Terracon to determine
the need for any shoring or underpinning. Excavations should not extend into the stress influence
zone of the existing foundations without prior evaluation by Terracon. The stress influence zone is
defined as the area below a line projected down at a 1(h) to 1(v) slope from the bottom edge of the
existing foundation. Excavations within the influence zone of existing foundations can result in loss
of support, and can create settlement or failure of the existing foundations. While the evaluation of
existing foundations and the design of a shoring system are beyond the scope of this study, we can
perform these tasks as a separate study.
The subgrade soil conditions should be evaluated during the excavation process and the stability
of the soils determined at that time by the contractors’ Competent Person. Slope inclinations flatter
than the OSHA maximum values may have to be used. The individual contractor(s) should be
made responsible for designing and constructing stable, temporary excavations as required to
maintain stability of both the excavation sides and bottom. All excavations should be sloped or
Geotechnical Engineering Report
Beta Tau Fraternity House Addition ■ Fort Collins, Colorado
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shored in the interest of safety following local, and federal regulations, including current OSHA
excavation and trench safety standards.
As a safety measure, it is recommended that all vehicles and soil piles be kept a minimum lateral
distance from the crest of the slope equal to the slope height. The exposed slope face should be
protected against the elements
Subgrade Preparation
After the undocumented existing fill (if any) has been removed from the building addition area,
the top 10 inches of the exposed ground surface should be scarified, moisture conditioned, and
recompacted to at least 95 percent of the maximum dry unit weight as determined by ASTM D698
before any new fill or foundation or pavement is placed.
If pockets of soft, loose, or otherwise unsuitable materials are encountered at the bottom of the
foundation excavations and it is inconvenient to lower the foundations, the proposed foundation
elevations may be reestablished by over-excavating the unsuitable soils and backfilling with
compacted engineered fill or lean concrete.
Our experience indicates the subgrade materials below existing pavements and other flatwork will
likely have relatively high moisture content and will tend to deflect and deform (pump) under
construction traffic wheel loads. After removal of pavements, 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 the excavation has been compacted, engineered fill can be placed to bring the
building addition pad and pavement subgrade to the desired grade. Engineered fill should be
placed in accordance with the recommendations presented in subsequent sections of this report.
The stability of the subgrade may be affected by precipitation, repetitive construction traffic or
other factors. If unstable conditions develop, workability may be improved by scarifying and
Geotechnical Engineering Report
Beta Tau Fraternity House Addition ■ Fort Collins, Colorado
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drying. Alternatively, over-excavation of wet zones and replacement with granular materials may
be used, or crushed gravel and/or rock can be tracked or “crowded” into the unstable surface soil
until a stable working surface is attained. Use of lime, fly ash or cement could also be considered
as a stabilization technique. Laboratory evaluation is recommended to determine the effect of
chemical stabilization on subgrade soils prior to construction. Lightweight excavation equipment
may also be used to reduce subgrade pumping.
Fill Materials
The on-site soils or approved granular and low plasticity cohesive imported materials may be used
as fill material. The earthwork contractor should expect significant mechanical processing and
moisture conditioning of the site soils and/or bedrock will be needed to achieve proper compaction
Imported soils (if required) should meet the following material property requirements:
Gradation Percent finer by weight (ASTM C136)
4” 100
3” 70-100
No. 4 Sieve 50-100
No. 200 Sieve 65 (max.)
Soil Properties Values
Liquid Limit 35 (max.)
Plasticity Index 15 (max.)
Other import fill materials types may be suitable for use on the site depending upon proposed
application and location on the site, and could be tested and approved for use on a case-by-case
basis.
Compaction Requirements
Engineered fill should be placed and compacted in horizontal lifts, using equipment and procedures
that will produce recommended moisture contents and densities throughout the lift.
Geotechnical Engineering Report
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Item Description
Fill lift thickness
9 inches or less in loose thickness when heavy, self-
propelled compaction equipment is used
4 to 6 inches in loose thickness when hand-guided
equipment (i.e. jumping jack or plate compactor) is used
Minimum compaction requirements
95 percent of the maximum dry unit weight as determined by
ASTM D698.
Moisture content cohesive soil (clay) -1 to +3 % of the optimum moisture content
Moisture content cohesionless soil
(sand)
-3 to +3 % of the optimum moisture content
1. We recommend engineered fill be tested for moisture content and compaction during placement. Should the
results of the in-place density tests indicate the specified moisture or compaction limits have not been met,
the area represented by the test should be reworked and retested as required until the specified moisture
and compaction requirements are achieved.
2. Specifically, moisture levels should be maintained low enough to allow for satisfactory compaction to be
achieved without the fill material pumping when proof rolled.
3. Moisture conditioned clay materials should not be allowed to dry out. A loss of moisture within these materials
could result in an increase in the material’s expansive potential. Subsequent wetting of these materials could
result in undesirable movement.
Utility Trench Backfill
All trench excavations should be made with sufficient working space to permit construction including
backfill placement and compaction.
All underground piping within or near the proposed structure should be designed with flexible
couplings, so minor deviations in alignment do not result in breakage or distress. Utility knockouts
in foundation walls should be oversized to accommodate differential movements. It is imperative
that utility trenches be properly backfilled with relatively clean materials. If utility trenches are
backfilled with relatively clean granular material, they should be capped with at least 18 inches of
cohesive fill in non-pavement areas to reduce the infiltration and conveyance of surface water
through the trench backfill.
Utility trenches are a common source of water infiltration and migration. All utility trenches that
penetrate beneath the buildings should be effectively sealed to restrict water intrusion and flow
through the trenches that could migrate below the buildings. We recommend constructing an
effective clay “trench plug” that extends at least 5 feet out from the face of the building exteriors.
The plug material should consist of clay compacted at a water content at or above the soil’s optimum
water content. The clay fill should be placed to completely surround the utility line and be compacted
in accordance with recommendations in this report.
It is strongly recommended that a representative of Terracon provide full-time observation and
compaction testing of trench backfill within building addition and pavement areas.
Geotechnical Engineering Report
Beta Tau Fraternity House Addition ■ Fort Collins, Colorado
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Grading and Drainage
Grades must be adjusted to provide effective drainage away from the proposed building addition
and existing building during construction and maintained throughout the life of the proposed
project. Infiltration of water into foundation excavations must be prevented during construction.
Landscape irrigation adjacent to foundations should be minimized or eliminated. Water permitted
to pond near or adjacent to the perimeter of the structures (either during or post-construction) can
result in significantly higher soil movements than those discussed in this report. As a result, any
estimations of potential movement described in this report cannot be relied upon if positive
drainage is not obtained and maintained, and water is allowed to infiltrate the fill and/or subgrade.
Exposed ground (if any) should be sloped at a minimum of 10 percent grade for at least 5 feet
beyond the perimeter of the proposed buildings, where possible. Locally, flatter grades may be
necessary to transition ADA access requirements for flatwork. The use of swales, chases and/or
area drains may be required to facilitate drainage in unpaved areas around the perimeter of the
buildings. Backfill against foundations and exterior walls should be properly compacted and free
of all construction debris to reduce the possibility of moisture infiltration. After construction of the
proposed buildings and prior to project completion, we recommend verification of final grading be
performed to document positive drainage, as described above, has been achieved.
Flatwork and pavements will be subject to post-construction movement. Maximum grades
practical should be used for paving and flatwork to prevent areas where water 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 building line(s).
Low-volume, drip style landscaped irrigation should be used sparingly near the building. Roof
drains should discharge on to pavements or be extended away from the structures a minimum of
10 feet through the use of splash blocks or downspout extensions. A preferred alternative is to
have the roof drains discharge by solid pipe to storm sewers, a detention pond, or other
appropriate outfall.
Exterior Slab Design and Construction
Exterior slabs on-grade, exterior architectural features, and utilities founded on, or in backfill or
the site soils will likely experience some movement due to the volume change of the material.
Potential movement could be reduced by:
Geotechnical Engineering Report
Beta Tau Fraternity House Addition ■ Fort Collins, Colorado
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◼ Minimizing moisture increases in the backfill;
◼ Controlling moisture-density during placement of the backfill;
◼ Using designs which allow vertical movement between the exterior features and
adjoining structural elements; and
◼ Placing control joints on relatively close centers.
Construction Observation and Testing
The earthwork efforts should be monitored under the direction of Terracon. Monitoring should
include documentation of adequate removal of vegetation and topsoil, proof rolling, and mitigation
of areas delineated by the proof roll to require mitigation. Each lift of compacted fill should be
tested, evaluated, and reworked as necessary until approved by Terracon prior to placement of
additional lifts.
In areas of foundation excavations, the bearing subgrade should be evaluated under the direction
of Terracon. In the event that unanticipated conditions are encountered, Terracon should
prescribe mitigation options.
In addition to the documentation of the essential parameters necessary for construction, the
continuation of Terracon into the construction phase of the project provides the continuity to
maintain Terracon’s evaluation of subsurface conditions, including assessing variations and
associated design changes.
SHALLOW FOUNDATIONS
If the site has been prepared in accordance with the requirements noted in Earthwork, the
following design parameters are applicable for shallow foundations.
Spread Footings - Design Recommendations
Description Values
Bearing material
Properly prepared on-site soil, or new, properly
placed engineered fill.
Maximum net allowable bearing pressure
1 2,500 psf
Minimum foundation dimensions
Columns: 30 inches
Continuous: 18 inches
Lateral earth pressure coefficients
2
Active, Ka = 0.31
Passive, Kp = 3.26
At-rest, Ko = 0.47
Sliding coefficient
2
µ = 0.50
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Description Values
Moist soil unit weight ɣ = 130 pcf
Minimum embedment depth below finished
grade
3 30 inches
Subgrade modulus
k1 = 80 psi/in
𝐾(𝐵𝑥𝐵)
= 𝐾1
(
1
𝐵
)
𝐾(𝐵𝑥𝐿)
=
𝐾(𝐵𝑥𝐵)
(1 + 0.5 ∗ (
𝐵
𝐿))
1.5
Where:
k1 = coefficient of subgrade reaction of
foundations measuring 1 ft. x 1ft.
K(BxB) = coefficient of subgrade modulus for a
square foundation having dimensions BxB.
K(BxL) = coefficient of subgrade modulus for a
rectangular foundation having dimensions BxL.
Estimated total movement
4 About 1 inch
Estimated differential movement
4 About ½ to ¾ of total movement
1. The recommended maximum net allowable bearing pressure assumes any unsuitable fill or soft/loose soils,
if encountered, will be over-excavated and replaced with properly compacted engineered fill. The design
bearing pressure applies to a dead load plus design live load condition. The design bearing pressure may
be increased by one-third when considering total loads that include wind or seismic conditions.
2. The lateral earth pressure coefficients and sliding coefficients are ultimate values and do not include a factor
of safety. The foundation designer should include the appropriate factors of safety.
3. For frost protection and to reduce the effects of seasonal moisture variations in the subgrade soils. The
minimum embedment depth is for perimeter footings beneath unheated areas and is relative to lowest
adjacent finished grade, typically exterior grade. Interior column pads in heated areas should bear at least
12 inches below the adjacent grade (or top of the floor slab) for confinement of the bearing materials and to
develop the recommended bearing pressure.
4. The estimated movements presented above are based on the assumption that the maximum footing size is
4 feet for column footings and 1.5 feet for continuous footings. Larger foundation footprints will likely require
reduced net allowable soil bearing pressures to reduce risk for potential settlement.
Footings should be proportioned to reduce differential foundation movement. As discussed, total
movement resulting from the assumed structural loads is estimated to be on the order of about 1
inch. Additional foundation movements could occur if water from any source infiltrates the
foundation soils; therefore, proper drainage should be provided in the final design and during
construction and throughout the life of the structure. Failure to maintain the proper drainage as
recommended in the Grading and Drainage section of the Earthwork section of this report will
nullify the movement estimates provided above.
Geotechnical Engineering Report
Beta Tau Fraternity House Addition ■ Fort Collins, Colorado
August 5, 2020 ■ Terracon Project No. 20205071
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Spread Footings - Construction Considerations
To reduce the potential of “pumping” and softening of the foundation soils at the foundation
bearing level and the requirement for corrective work, we suggest the foundation excavation for
the building addition be completed remotely with a track-hoe operating outside of the excavation
limits.
Spread footing construction should only be considered if the estimated foundation movement can
be tolerated. Subgrade soils beneath footings should be moisture conditioned and compacted as
described in the Earthwork section of this report. The moisture content and compaction of
subgrade soils should be maintained until foundation construction.
Footings and foundation walls should be reinforced as necessary to reduce the potential for distress
caused by differential foundation movement.
Unstable surfaces will need to be stabilized prior to backfilling excavations and/or constructing
the building foundation, floor slab and/or project pavements. The use of angular rock, recycled
concrete and/or gravel pushed or “crowded” into the yielding subgrade is considered suitable
means of stabilizing the subgrade. The use of geogrid materials in conjunction with gravel could
also be considered and could be more cost effective.
Unstable subgrade conditions should be observed by Terracon to assess the subgrade and
provide suitable alternatives for stabilization. Stabilized areas should be proof rolled prior to
continuing construction to assess the stability of the subgrade.
Foundation excavations should be observed by Terracon. If the soil conditions encountered differ
significantly from those presented in this report, supplemental recommendations will be required.
Construction Adjacent to Existing Building
Differential settlement between the additions and the existing building is expected to approach
the magnitude of the total settlement of the addition. Expansion joints should be provided between
the existing building and the proposed addition to accommodate differential movements between
the two structures. Underground piping between the two structures should be designed with
flexible couplings and utility knockouts in foundation walls should be oversized, so minor
deflections in alignment do not result in breakage or distress. Care should be taken during
excavation adjacent to existing foundations, to avoid disturbing existing foundation bearing soils.
New footings should bear at or near the bearing elevation of immediately adjacent existing
foundations. Depending upon their locations and current loads on the existing footings, footings
for the new addition could cause settlement of adjacent walls. To reduce this concern and risk,
Geotechnical Engineering Report
Beta Tau Fraternity House Addition ■ Fort Collins, Colorado
August 5, 2020 ■ Terracon Project No. 20205071
Responsive ■ Resourceful ■ Reliable 14
clear distances at least equal to the new footing widths should be maintained between the
addition’s footings and footings supporting the existing building.
We understand existing foundations may support additional load from the walls of the new
additions. It is possible additional loads on the existing foundations could cause other building
settlements to occur. The structural capacity of existing foundations should be evaluated by a
licensed structural engineer, where increases in loading are planned.
SEISMIC CONSIDERATIONS
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/bedrock properties encountered at the site and as described on the exploration
logs and results, it is our professional opinion that the Seismic Site Classification is D.
Subsurface explorations at this site were extended to a maximum depth of 25½ 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
testing may be performed to confirm the conditions below the current boring depth.
FLOOR SYSTEM
We understand a crawl space is planned for the building addition. If a slab-on-grade is utilized for
the interior floor system for the proposed building addition, Terracon should be contacted for
design recommendations.
Building codes should be followed for clear space requirements below structurally supported
floors with crawl space areas and will depend, in part, upon the type of materials used to construct
the floor as well as the volumetric expansion potential of the underlying soil/bedrock. Minimum
clear spaces for these types of floors normally range from about 18 to 24 inches.
It is prudent to maintain a minimum clear space below all plumbing lines and other conduits. A
minimum clear space of 10 inches should be provided for this application. This can be
accomplished by hanging plumbing/conduits on the underside of the structural floor or by
trenching below lines.
Irrigation and surface water can penetrate backfill adjacent to the building and collect at the bottom
of crawl space excavations resulting in a perched groundwater condition. Experience indicates
Geotechnical Engineering Report
Beta Tau Fraternity House Addition ■ Fort Collins, Colorado
August 5, 2020 ■ Terracon Project No. 20205071
Responsive ■ Resourceful ■ Reliable 15
over a period of time, moist conditions and possibly standing water can develop in crawl space
areas, particularly if proper surface drainage away from the foundation is not provided and
maintained or if over-watering of lawns and other landscape plantings adjacent to the foundation
occurs. Consequently, we recommend the provision of a drain where a suspended structural floor
with a crawl space area is used.
At a minimum, the drain trench and pipe should be constructed around the interior perimeter of
the building addition foundation and should be sloped at a minimum ½ percent to a suitable outlet,
such as a sump and pump system or to a positive gravity outfall. The drainage system should
consist of a minimum 4-inch diameter rigid perforated pipe, embedded in free-draining gravel,
placed in a trench at least 12-inches in width. The invert of the drain pipe should be at least 4
inches below the bottom of the grade beam void or the crawl space subgrade at the highest point.
The pipe should be encased with washed gravel and the gravel should extend laterally to the
grade beam void and at least ½ the height of the void. The gravel should be covered with drainage
fabric to reduce infiltration of fines into and clogging of the gravel media and pipe. Lateral lines
placed at regular intervals should be considered to help drain interior areas of the crawl space.
Crawl space areas should be well ventilated to help manage humidity and to facilitate moisture
release. This will require active ventilation using fans or other appropriate means. A mechanical
engineer experienced in these issues should be consulted to properly design a ventilation system.
To help promote drainage towards the perimeter of the structure, the crawl space subgrade
should be excavated to a minimum 1 percent slope from the high point at the center of crawl
space areas to the perimeter of the building addition foundation. To further manage humidity,
consideration should be given to placing a vapor retarder (10 mil polyethylene membrane
material, or equivalent) on the exposed soil in the crawl space. The vapor retarder should be
sealed at joints and attached to concrete foundation elements.
Grade beams/foundation walls with unbalanced backfill levels on opposite sides (such as crawl
space walls) should be designed for lateral earth pressures imposed by the backfill. Earth
pressures will primarily be influenced by structural design of the walls, conditions of wall restraint
and type, compaction and drainage of the backfill. For purposes of design, we have assumed
about 3 to 5 feet of fill will be retained by crawl space walls and backfill will consist of the on-site
clays or other approved cohesive materials. If taller walls are planned, or if different type of backfill
is used, we should be contacted to review our data and confirm or modify the design criteria
presented BELOW-GRADE STRUCTURES section of this report.
Geotechnical Engineering Report
Beta Tau Fraternity House Addition ■ Fort Collins, Colorado
August 5, 2020 ■ Terracon Project No. 20205071
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BELOW-GRADE STRUCTURES
Lateral Earth Pressures
Below-grade structures or reinforced concrete walls with unbalanced backfill levels on opposite
sides should be designed for earth pressures at least equal to those indicated in the following
table. Earth pressures will be influenced by structural design of the walls, conditions of wall
restraint, methods of construction and/or compaction and the strength of the materials being
restrained. Two wall restraint conditions are shown. Active earth pressure is commonly used for
design of free-standing cantilever retaining walls and assumes wall movement. The "at-rest"
condition assumes no wall movement. The recommended design lateral earth pressures do not
include a factor of safety and do not provide for possible hydrostatic pressure on the walls.
Earth Pressure Coefficients
Earth Pressure
Conditions
Coefficient for
Backfill Type
Equivalent Fluid
Density (pcf)
Surcharge
Pressure, p1 (psf)
Earth Pressure,
p2 (psf)
Active (Ka) Granular - 0.33
Lean Clay - 0.31
42
40
(0.33)S
(0.31)S
(42)H
(40)H
At-Rest (Ko) Granular - 0.46
Lean Clay - 0.47
60
61
(0.46)S
(0.47)S
(60)H
(61)H
Passive (Kp) Granular - 3.0
Lean Clay – 3.2
390
410
---
---
---
---
Applicable conditions to the above include:
■ For active earth pressure, wall must rotate about base, with top lateral movements of about
0.002 H to 0.004 H, where H is wall height
■ For passive earth pressure to develop, wall must move horizontally to mobilize resistance
■ Uniform surcharge, where S is surcharge pressure
■ In-situ soil backfill weight a maximum of 130 pcf
Geotechnical Engineering Report
Beta Tau Fraternity House Addition ■ Fort Collins, Colorado
August 5, 2020 ■ Terracon Project No. 20205071
Responsive ■ Resourceful ■ Reliable 17
■ Horizontal backfill, compacted between 95 and 98 percent of standard Proctor maximum
dry density
■ Loading from heavy compaction equipment not included
■ No hydrostatic pressures acting on wall
■ No dynamic loading
■ No safety factor included
■ Ignore passive pressure in frost zone
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 and passive cases,
respectively. To calculate the resistance to sliding, a value of 0.50 should be used as the ultimate
coefficient of friction between the footing and the underlying soil.
PAVEMENTS
Pavements – Subgrade Preparation
On most project sites, the site grading is accomplished relatively early in the construction phase.
Fills are typically placed and compacted in a uniform manner. However as construction proceeds,
the subgrade may be disturbed due to utility excavations, construction traffic, desiccation, or
rainfall/snow melt. As a result, the pavement subgrade may not be suitable for pavement
construction and corrective action will be required. The subgrade should be carefully evaluated
at the time of pavement construction for signs of disturbance or instability. We recommend the
pavement subgrade be thoroughly proof rolled with a loaded tandem-axle dump truck prior to final
grading and paving. All pavement areas should be moisture conditioned and properly compacted
to the recommendations in this report immediately prior to paving.
Pavements – Design Recommendations
Design of new privately-maintained pavements for the project has been based on the procedures
described by the National Asphalt Pavement Associations (NAPA) and the American Concrete
Institute (ACI).
We assumed the following design parameters for NAPA flexible pavement thickness design:
◼ Automobile Parking Areas
• Class I - Parking stalls and parking lots for cars and pick-up trucks, with
Equivalent Single Axle Load (ESAL) up to 7,000 over 20 years
◼ Main Traffic Corridors
Geotechnical Engineering Report
Beta Tau Fraternity House Addition ■ Fort Collins, Colorado
August 5, 2020 ■ Terracon Project No. 20205071
Responsive ■ Resourceful ■ Reliable 18
• Class II – Parking lots with a maximum of 10 trucks per day with Equivalent
Single Axle Load (ESAL) up to 27,000 over 20 years (including trash and
delivery trucks)
◼ Subgrade Soil Characteristics
• USCS Classification – CL, classified by NAPA as poor
We assumed the following design parameters for ACI rigid pavement thickness design based
upon the average daily truck traffic (ADTT):
◼ Automobile Parking Areas
• ACI Category A: Automobile parking with an ADTT of 1 over 20 years
◼ Main Traffic Corridors
• ACI Category A: Automobile parking area and service lanes with an ADTT of
up to 10 over 20 years
◼ Subgrade Soil Characteristics
• USCS Classification – CL
◼ Concrete modulus of rupture value of 600 psi
We should be contacted to confirm and/or modify the recommendations contained herein if actual
traffic volumes differ from the assumed values shown above.
Recommended alternatives for flexible and rigid pavements are summarized for each traffic area
as follows:
Traffic Area Alternative
Recommended Pavement Thicknesses (Inches)
Asphaltic
Concrete
Surface
Aggregate
Base Course
Portland
Cement
Concrete
Total
Automobile Parking
(NAPA Class I and
ACI Category A)
A 3½ 6 - 9½
B - - 5 5
Service Lanes
(NAPA Class II and
ACI Category A)
A 5 6 - 11
B - - 6 6
Aggregate base course (if used on the site) should consist of a blend of sand and gravel which
meets strict specifications for quality and gradation. Use of materials meeting Colorado
Department of Transportation (CDOT) Class 5 or 6 specifications is recommended for aggregate
base course. Aggregate base course should be placed in lifts not exceeding 6 inches and
compacted to a minimum of 95 percent of the maximum dry unit weight as determined by ASTM
D698.
Geotechnical Engineering Report
Beta Tau Fraternity House Addition ■ Fort Collins, Colorado
August 5, 2020 ■ Terracon Project No. 20205071
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Asphaltic concrete should be composed of a mixture of aggregate, filler and additives (if required)
and approved bituminous material. The asphalt concrete should conform to approved mix
designs stating the Superpave properties, optimum asphalt content, job mix formula and
recommended mixing and placing temperatures. Aggregate used in asphalt concrete should
meet particular gradations. Material meeting CDOT Grading S or SX specifications or equivalent
is recommended for asphalt concrete. Mix designs should be submitted prior to construction to
verify their adequacy. Asphalt material should be placed in maximum 3-inch lifts and compacted
within a range of 92 to 96 percent of the theoretical maximum (Rice) density (ASTM D2041).
Where rigid pavements are used, the concrete should be produced from an approved mix design
with the following minimum properties:
Properties Value
Compressive strength 4,000 psi
Cement type Type I or II portland cement
Entrained air content (%) 5 to 8
Concrete aggregate ASTM C33 and CDOT section 703
Concrete should be deposited by truck mixers or agitators and placed a maximum of 90 minutes
from the time the water is added to the mix. Longitudinal and transverse joints should be provided
as needed in concrete pavements for expansion/contraction and isolation per ACI 325. The
location and extent of joints should be based upon the final pavement geometry.
For areas subject to concentrated and repetitive loading conditions (if any) such as dumpster
pads, truck delivery docks and ingress/egress aprons, we recommend using a portland cement
concrete pavement with a thickness of at least 6 inches underlain by at least 4 inches of granular
base. Prior to placement of the granular base, the areas should be thoroughly proof rolled. For
dumpster pads, the concrete pavement area should be large enough to support the container and
tipping axle of the refuse truck.
Pavement performance is affected by its surroundings. In addition to providing preventive
maintenance, the civil engineer should consider the following recommendations in the design and
layout of pavements:
■ Site grades should slope a minimum of 2 percent away from the pavements;
■ The subgrade and the pavement surface have a minimum 2 percent slope to promote proper
surface drainage;
■ Consider appropriate edge drainage and pavement under drain systems;
■ Install pavement drainage surrounding areas anticipated for frequent wetting;
■ Install joint sealant and seal cracks immediately;
Geotechnical Engineering Report
Beta Tau Fraternity House Addition ■ Fort Collins, Colorado
August 5, 2020 ■ Terracon Project No. 20205071
Responsive ■ Resourceful ■ Reliable 20
■ Seal all landscaped areas in, or adjacent to pavements to reduce moisture migration to
subgrade soils; and
■ Placing compacted, low permeability backfill against the exterior side of curb and gutter.
Pavements – Construction Considerations
Openings in pavement, such as landscape islands, are sources for water infiltration into
surrounding pavements. Water collects in the islands and migrates into the surrounding subgrade
soils thereby degrading support of the pavement. This is especially applicable for islands with
raised concrete curbs, irrigated foliage, and low permeability near-surface soils. The civil design
for the pavements with these conditions should include features to restrict or to collect and
discharge excess water from the islands. Examples of features are edge drains connected to the
storm water collection system or other suitable outlet and impermeable barriers preventing lateral
migration of water such as a cutoff wall installed to a depth below the pavement structure.
Pavements – Maintenance
Preventative maintenance should be planned and provided for an ongoing pavement
management program in order to enhance future pavement performance. Preventive
maintenance consists of both localized maintenance (e.g. crack and joint sealing and patching)
and global maintenance (e.g. surface sealing). Preventative maintenance is usually the first
priority when implementing a planned pavement maintenance program and provides the highest
return on investment for pavements.
CORROSIVITY
At the time this report was prepared, the laboratory testing for water-soluble sulfates had not been
completed. We will submit a supplemental section with the testing results and recommendations
once the testing has been completed.
GENERAL COMMENTS
Our analysis and opinions are based upon our understanding of the project, the geotechnical
conditions in the area, and the data obtained from our site exploration. Natural variations will occur
between exploration point locations or due to the modifying effects of construction or weather.
The nature and extent of such variations may not become evident until during or after construction.
Terracon should be retained as the Geotechnical Engineer, where noted in this report, to provide
observation and testing services during pertinent construction phases. If variations appear, we
can provide further evaluation and supplemental recommendations. If variations are noted in the
absence of our observation and testing services on-site, we should be immediately notified so
that we can provide evaluation and supplemental recommendations.
Geotechnical Engineering Report
Beta Tau Fraternity House Addition ■ Fort Collins, Colorado
August 5, 2020 ■ Terracon Project No. 20205071
Responsive ■ Resourceful ■ Reliable 21
Our Scope of Services does not include either specifically or by implication any environmental or
biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of
pollutants, hazardous materials or conditions. If the owner is concerned about the potential for
such contamination or pollution, other studies should be undertaken.
Our services and any correspondence or collaboration through this system are intended for the
sole benefit and exclusive use of our client for specific application to the project discussed and
are accomplished in accordance with generally accepted geotechnical engineering practices with
no third-party beneficiaries intended. Any third-party access to services or correspondence is
solely for information purposes to support the services provided by Terracon to our client.
Reliance upon the services and any work product is limited to our client, and is not intended for
third parties. Any use or reliance of the provided information by third parties is done solely at their
own risk. No warranties, either express or implied, are intended or made.
Site characteristics as provided are for design purposes and not to estimate excavation cost. Any
use of our report in that regard is done at the sole risk of the excavating cost estimator as there
may be variations on the site that are not apparent in the data that could significantly impact
excavation cost. Any parties charged with estimating excavation costs should seek their own site
characterization for specific purposes to obtain the specific level of detail necessary for costing.
Site safety, and cost estimating including, excavation support, and dewatering
requirements/design are the responsibility of others. If changes in the nature, design, or location
of the project are planned, our conclusions and recommendations shall not be considered valid
unless we review the changes and either verify or modify our conclusions in writing.
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ATTACHMENTS
Contents:
EXPLORATION AND TESTING PROCEDURES
PHOTOGRAPHY LOG
SITE LOCATION AND EXPLORATION PLANS
EXPLORATION RESULTS
SUPPORTING INFORMATION
Note: Refer to each individual Attachment for a listing of contents.
Geotechnical Engineering Report
Beta Tau Fraternity House Addition ■ Fort Collins, Colorado
August 5, 2020 ■ Terracon Project No. 20205071
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EXPLORATION AND TESTING PROCEDURES
Field Exploration
Beta Tau prescribed the following boring locations:
Number of Borings Boring Depth (feet) Location
1 25 or auger refusal Planned building addition area
1 10 or auger refusal Planned parking/driveway area
Boring Layout and Elevations: We used handheld GPS equipment to locate borings with an
estimated horizontal accuracy of +/-20 feet. Field measurements from existing site features were
also utilized. A ground surface elevation at each boring location was obtained by Terracon using
an engineer’s level, referencing an on-site benchmark. The on-site benchmark consisted of the
F.F.E of the most eastern exterior door with an elevation of 5,003.3 feet.
Subsurface Exploration Procedures: We advanced soil borings with a truck-mounted drill rig
using continuous-flight, solid-stem augers. Three samples were obtained in the upper 10 feet of
each boring and at intervals of 5 feet thereafter. Soil sampling will be performed using modified
California barrel and/or standard split-barrel sampling procedures. For the standard split-barrel
sampling procedure, a standard 2-inch outer diameter split-barrel sampling spoon is driven into
the ground by a 140-pound automatic hammer falling a distance of 30 inches. The number of
blows required to advance the sampling spoon the last 12 inches of a normal 18-inch penetration
is recorded as the Standard Penetration Test (SPT) resistance value. The SPT resistance values,
also referred to as N-values, are indicated on the boring logs at the test depths. For the modified
California barrel sampling procedure, a 2½-inch outer diameter split-barrel sampling spoon is
used for sampling. Modified California barrel sampling procedures are similar to standard split-
barrel sampling procedures; however, blow counts are typically recorded for 6-inch intervals for a
total of 12 inches of penetration. The samples were placed in appropriate containers, taken to our
soil laboratory for testing, and classified by a geotechnical engineer.
In addition, we observed and recorded groundwater levels during drilling observations.
Our exploration team prepared field boring logs as part of standard drilling operations including
sampling depths, penetration distances, and other relevant sampling information. Field logs
included visual classifications of materials encountered during drilling, and our interpretation of
subsurface conditions between samples. Final boring logs, prepared from field logs, represent
the geotechnical engineer's interpretation, and include modifications based on observations and
laboratory test results.
Geotechnical Engineering Report
Beta Tau Fraternity House Addition ■ Fort Collins, Colorado
August 5, 2020 ■ Terracon Project No. 20205071
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Property Disturbance: We backfilled borings with auger cuttings and bentonite chips after
completion. Pavements were patched with cold-mix asphalt. Our services did not include repair
of the site beyond backfilling our boreholes, and patching existing pavements/surfaces. Excess
auger cuttings were dispersed in the general vicinity of the boreholes. Because backfill material
often settles below the surface after a period, we recommend checking boreholes periodically and
backfilling, if necessary. We can provide this service for additional fees, at your request.
Laboratory Testing
The project engineer reviewed field data and assigned various laboratory tests to better
understand the engineering properties of various soil and bedrock strata. Laboratory testing was
conducted in general accordance with applicable or other locally recognized standards.
Procedural standards noted in this report are for reference to methodology in general. In some
cases, variations to methods are applied as a result of local practice or professional judgement.
Testing was performed under the direction of a geotechnical engineer and included the following:
■ Visual classification ■ Moisture content
■ Dry density ■ Atterberg limits
■ Grain-size analysis ■ One-dimensional swell
■ Water-soluble sulfates ■ Unconfined compressive strength
Our laboratory testing program includes examination of soil samples by an engineer. Based on
the material’s texture and plasticity, we described and classified soil samples in accordance with
the Unified Soil Classification System (USCS). Soil and bedrock samples obtained during our
field work will be disposed of after laboratory testing is complete unless a specific request is made
to temporarily store the samples for a longer period of time.
Bedrock samples obtained had rock classification conducted using locally accepted practices for
engineering purposes. Boring log rock classification is determined using the Description of Rock
Properties.
Geotechnical Engineering Report
Beta Tau Fraternity House Addition ■ Fort Collins, Colorado
August 5, 2020 ■ Terracon Project No. 20205071
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PHOTOGRAPHY LOG
Looking south at B1
Geotechnical Engineering Report
Beta Tau Fraternity House Addition ■ Fort Collins, Colorado
August 5, 2020 ■ Terracon Project No. 20205071
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Looking west at B2
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SITE LOCATION AND EXPLORATION PLANS
Contents:
Site Location Plan
Exploration Plan
Note: All attachments are one page unless noted above.
SITE LOCATION
Beta Tau Fraternity House Addition ■ Fort Collins, Colorado
August 5, 2020 ■ Terracon Project No. 20205071
SITE LOCA TION
DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY MICROSOFT BING MAPS
EXPLORATION PLAN
Beta Tau Fraternity House Addition ■ Fort Collins, Colorado
August 5, 2020 ■ Terracon Project No. 20205071
EXPLORATION P LAN
DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY MICROSOFT BING MAPS
EXPLORATION RESULTS
Contents:
GeoModel
Boring Logs (B1 and B2)
Atterberg Limits
Grain Size Distribution
Consolidation/Swell
Unconfined Compressive Strength
Note: All attachments are one page unless noted above.
4,976
4,978
4,980
4,982
4,984
4,986
4,988
4,990
4,992
4,994
4,996
4,998
5,000
5,002
5,004
ELEVATION (MSL) (feet)
Beta Tau Fraternity House Addition Fort Collins, CO
Terracon Project No. 20205071
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:
B2 B1
GEOMODEL
This is not a cross section. This is intended to display the Geotechnical Model only. See individual logs for more detailed conditions.
LEGEND
Vegetative Layer
Sandy Lean Clay
Asphalt
Weathered Rock
Model Layer Layer Name General Description
Sandy lean clay, trace gravel, brown to red brown, medium
1 stiff to very stiff
Claystone bedrock, brown to orange, very weathered, trace
2 FeOx
Lean Clay
Claystone Bedrock
10.5
1
24.5
25.5
1
2
4-5
3-4-3
N=7
2-3-3
N=6
+1.0/150 12.5 61
13.4
17.8
116 34-12-22
VEGETATIVE LAYER, native grass and weeds
about 2 inches thick
SANDY LEAN CLAY (CL), trace gravel, brown to
red brown, medium stiff
Boring Terminated at 10.5 Feet
0.1
10.5
5002+/-
4992+/-
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic, hammer efficiency = 85%
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20205071 BETA TAU FRATERNI.GPJ TERRACON_DATATEMPLATE.GDT 8/5/20
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
FIELD TEST
RESULTS
SWELL/CONSOL
(%/psf)
UNCONFINED
COMPRESSIVE
STRENGTH (psf)
PERCENT FINES
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
LOCATION See Exploration Plan
Latitude: 40.5681° Longitude: -105.0746°
GRAPHIC LOG
MODEL LAYER
DEPTH ELEVATION (Ft.)
Approximate Surface Elev.: 5002.3 (Ft.) +/-
Page 1 of 1
Advancement Method:
4-inch diameter soild-stem auger
Abandonment Method:
Boring backfilled with auger cuttings upon completion.
Notes:
Project No.: 20205071
Drill Rig: CME 55
BORING LOG NO. B1
CLIENT: Beta Tau 1919 Corporation
Denver, CO
Driller: Drilling Engineers, Inc.
Boring Completed: 07-24-2020
PROJECT: Beta Tau Fraternity House Addition
58
12.6
11.8
12.8
11.8
13.2
15.9
20.6
119
111
115
35-13-22
ASPHALT, about 2 inches thick
SANDY LEAN CLAY (CL), trace gravel, brown to
red brown, stiff
medium stiff
very stiff
WEATHERED CLAYSTONE, brown to orange,
very weathered, trace FeOx
Boring Terminated at 25.5 Feet
3-3-5
N=8
6-6
4-4-4
N=8
4-4
3-2-5
N=7
10-17
3-5-6
N=11
0.0/
1,000 4190
0.1
24.5
25.5
5002+/-
4977.5+/-
4976.5+/-
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic, hammer efficiency = 85%
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20205071 BETA TAU FRATERNI.GPJ TERRACON_DATATEMPLATE.GDT 8/5/20
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
15
20
25
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
LOCATION See Exploration Plan
Latitude: 40.5682° Longitude: -105.0748°
GRAPHIC LOG
MODEL LAYER
0
10
20
30
40
50
60
0 20 40 60 80 100
CL or OL CH or OH
ML or OL
MH or OH
"U" Line
"A" Line
ATTERBERG LIMITS RESULTS
ASTM D4318
P
L
A
S
T
I
C
I
T
Y
I
N
D
E
X
LIQUID LIMIT
PROJECT NUMBER: 20205071
SITE: 1516 Remington Street
Fort Collins, CO
PROJECT: Beta Tau Fraternity House Addition
CLIENT: Beta Tau 1919 Corporation
Denver, CO
1901 Sharp Point Dr Ste C
Fort Collins, CO
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. ATTERBERG LIMITS 20205071 BETA TAU FRATERNI.GPJ TERRACON_DATATEMPLATE.GDT 8/5/20
34
35
12
13
22
22
Boring ID Depth LL PL PI
B1
B2
61.4
58.1
Fines
2 - 3
9 - 10
CL
CL
SANDY LEAN CLAY
SANDY LEAN CLAY
USCS Description
CL-ML
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
100 10 1 0.1 0.01 0.001
30 40
1.5 50
6 8 200
4 10 14
1 3/4
1/2 60
GRAIN SIZE IN MILLIMETERS
PERCENT FINER BY WEIGHT
U.HYDROMETERS. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS
4 3/8
3 3 100 140
2
GRAIN SIZE DISTRIBUTION
ASTM D422 / ASTM C136
6 16
20
PROJECT NUMBER: 20205071
SITE: 1516 Remington Street
Fort Collins, CO
PROJECT: Beta Tau Fraternity House Addition
CLIENT: Beta Tau 1919 Corporation
Denver, CO
1901 Sharp Point Dr Ste C
Fort Collins, CO
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GRAIN SIZE: USCS-2 20205071 BETA TAU FRATERNI.GPJ TERRACON_DATATEMPLATE.GDT 8/5/20
B1
B2
coarse fine coarse medium fine
COBBLES GRAVEL SAND
SILT OR CLAY
SANDY LEAN CLAY (CL)
SANDY LEAN CLAY (CL)
34
35
22
22
12
13
-10
-8
-6
-4
-2
0
2
4
100 1,000 10,000
AXIAL STRAIN, %
PRESSURE, psf
NOTES: Sample exhibited 1.0 percent swell upon wetting under an applied pressure of 150 psf.
SWELL CONSOLIDATION TEST
ASTM D4546
PROJECT NUMBER: 20205071
SITE: 1516 Remington Street
Fort Collins, CO
PROJECT: Beta Tau Fraternity House Addition
CLIENT: Beta Tau 1919 Corporation
Denver, CO
1901 Sharp Point Dr Ste C
Fort Collins, CO
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. TC_CONSOL_STRAIN-USCS 20205071 BETA TAU FRATERNI.GPJ TERRACON_DATATEMPLATE.GDT 8/5/20
B1 2 - 3 ft SANDY LEAN CLAY(CL) 116 12.5
Specimen Identification Classification , pcf WC, %
-10
-8
-6
-4
-2
0
2
4
100 1,000 10,000
AXIAL STRAIN, %
PRESSURE, psf
NOTES: Sample exhibited no movement upon wetting under an applied pressure of 1,000 psf.
SWELL CONSOLIDATION TEST
ASTM D4546
PROJECT NUMBER: 20205071
SITE: 1516 Remington Street
Fort Collins, CO
PROJECT: Beta Tau Fraternity House Addition
CLIENT: Beta Tau 1919 Corporation
Denver, CO
1901 Sharp Point Dr Ste C
Fort Collins, CO
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. TC_CONSOL_STRAIN-USCS 20205071 BETA TAU FRATERNI.GPJ TERRACON_DATATEMPLATE.GDT 8/5/20
B2 9 - 10 ft SANDY LEAN CLAY(CL) 108 11.8
Specimen Identification Classification , pcf WC, %
0
500
1,000
1,500
2,000
2,500
3,000
3,500
4,000
4,500
0 1.0 2.0 3.0 4.0 5.0
AXIAL STRAIN - %
UNCONFINED COMPRESSION TEST
ASTM D2166
COMPRESSIVE STRESS - psf
PROJECT NUMBER: 20205071
SITE: 1516 Remington Street
Fort Collins, CO
PROJECT: Beta Tau Fraternity House Addition
CLIENT: Beta Tau 1919 Corporation
Denver, CO
1901 Sharp Point Dr Ste C
Fort Collins, CO
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. UNCONFINED WITH PHOTOS 20205071 BETA TAU FRATERNI.GPJ TERRACON_DATATEMPLATE.GDT 8/5/20
SAMPLE TYPE: CARS SAMPLE LOCATION: B2 @ 9 - 10 feet
0.49
63.78
111
Strain Rate: in/min
Failure Strain: %
Calculated Saturation: %
Height: in.
Diameter: in.
SPECIMEN FAILURE PHOTOGRAPH
Remarks:
58
LL PL PI Percent < #200 Sieve
2094
DESCRIPTION: SANDY LEAN CLAY(CL)
Dry Density: pcf
Moisture Content: %
2.81
2.07
2.65
Height / Diameter Ratio:
Calculated Void Ratio:
Undrained Shear Strength: (psf)
Unconfined Compressive Strength (psf)
35 13 22
Assumed Specific Gravity:
4188
3.98
1.93
SPECIMEN TEST DATA
11.8
SUPPORTING INFORMATION
Contents:
General Notes
Unified Soil Classification System
Description of Rock Properties
Note: All attachments are one page unless noted above.
Terracon Project No. 20205071
Beta Tau Fraternity House Addition Fort Collins, CO
2,000 to 4,000
Unconfined
Compressive
Strength
Qu, (psf)
less than 500
500 to 1,000
1,000 to 2,000
4,000 to 8,000
> 8,000
Modified
California
Ring
Sampler
Standard
Penetration
Test
Water Initially
Encountered
Water Level After a
Specified Period of Time
Water Level After
a Specified Period of Time
Cave In
Encountered
Exploration point locations as shown on the Exploration Plan and as noted on the soil boring logs in the form of Latitude and
Longitude are approximate. See Exploration and Testing Procedures in the report for the methods used to locate the
exploration points for this project. Surface elevation data annotated with +/- indicates that no actual topographical survey was
conducted to confirm the surface elevation. Instead, the surface elevation was approximately determined from topographic
maps of the area.
LOCATION AND ELEVATION NOTES
Soil classification as noted on the soil boring logs is based Unified Soil Classification System. Where sufficient laboratory data
exist to classify the soils consistent with ASTM D2487 "Classification of Soils for Engineering Purposes" this procedure is used.
ASTM D2488 "Description and Identification of Soils (Visual-Manual Procedure)" is also used to classify the soils, particularly
where insufficient laboratory data exist to classify the soils in accordance with ASTM D2487. In addition to USCS classification,
coarse grained soils are classified on the basis of their in-place relative density, and fine-grained soils are classified on the basis
of their consistency. See "Strength Terms" table below for details. The ASTM standards noted above are for reference to
methodology in general. In some cases, variations to methods are applied as a result of local practice or professional judgment.
DESCRIPTIVE SOIL CLASSIFICATION
The soil boring logs contained within this document are intended for application to the project as described in this document.
Use of these soil boring logs for any other purpose may not be appropriate.
RELEVANCE OF SOIL BORING LOG
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
UNIFIED SOIL CLASSIFICATION SYSTEM
UNIFIED SOIL CLASSI FICATI ON SYSTEM
Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A
Soil Classification
Group
Symbol
Group Name B
Coarse-Grained Soils:
More than 50% retained
on No. 200 sieve
Gravels:
More than 50% of
coarse fraction
retained on No. 4 sieve
Clean Gravels:
Less than 5% fines C
Cu 4 and 1 Cc 3 E
GW Well-graded gravel F
Cu 4 and/or [Cc<1 or Cc>3.0] E
GP Poorly graded gravel F
Gravels with Fines:
More than 12% fines C
Fines classify as ML or MH GM Silty gravel F, G, H
Fines classify as CL or CH GC Clayey gravel F, G, H
Sands:
50% or more of coarse
fraction passes No. 4
sieve
Clean Sands:
Less than 5% fines D
Cu 6 and 1 Cc 3 E
SW Well-graded sand I
Cu 6 and/or [Cc<1 or Cc>3.0] E
SP Poorly graded sand I
Sands with Fines:
More than 12% fines D
Fines classify as ML or MH SM Silty sand G, H, I
Fines classify as CL or CH SC Clayey sand G, H, I
Fine-Grained Soils:
50% or more passes the
No. 200 sieve
Silts and Clays:
Liquid limit less than 50
Inorganic:
PI 7 and plots on or above “A”
line J
CL Lean clay K, L, M
PI 4 or plots below “A” line J
ML Silt K, L, M
Organic:
Liquid limit - oven dried
0.75 OL
Organic clay K, L, M, N
Liquid limit - not dried Organic silt K, L, M, O
Silts and Clays:
Liquid limit 50 or more
Inorganic:
PI plots on or above “A” line CH Fat clay K, L, M
PI plots below “A” line MH Elastic Silt K, L, M
Organic:
DESCRIPTION OF ROCK PROPERTIES
ROCK VERSION 1
WEATHERING
Term Description
Unweathered No visible sign of rock material weathering, perhaps slight discoloration on major discontinuity surfaces.
Slightly
weathered
Discoloration indicates weathering of rock material and discontinuity surfaces. All the rock material may be
discolored by weathering and may be somewhat weaker externally than in its fresh condition.
Moderately
weathered
Less than half of the rock material is decomposed and/or disintegrated to a soil. Fresh or discolored rock is
present either as a continuous framework or as corestones.
Highly
weathered
More than half of the rock material is decomposed and/or disintegrated to a soil. Fresh or discolored rock is
present either as a discontinuous framework or as corestones.
Completely
weathered
All rock material is decomposed and/or disintegrated to soil. The original mass structure is still largely intact.
Residual soil
All rock material is converted to soil. The mass structure and material fabric are destroyed. There is a large
change in volume, but the soil has not been significantly transported.
STRENGTH OR HARDNESS
Description Field Identification
Uniaxial Compressive
Strength, psi (MPa)
Extremely weak Indented by thumbnail 40-150 (0.3-1)
Very weak
Crumbles under firm blows with point of geological hammer, can be
peeled by a pocket knife
150-700 (1-5)
Weak rock
Can be peeled by a pocket knife with difficulty, shallow indentations
made by firm blow with point of geological hammer
700-4,000 (5-30)
Medium strong
Cannot be scraped or peeled with a pocket knife, specimen can be
fractured with single firm blow of geological hammer
4,000-7,000 (30-50)
Strong rock
Specimen requires more than one blow of geological hammer to
fracture it
7,000-15,000 (50-100)
Very strong Specimen requires many blows of geological hammer to fracture it 15,000-36,000 (100-250)
Extremely strong Specimen can only be chipped with geological hammer >36,000 (>250)
DISCONTINUITY DESCRIPTION
Fracture Spacing (Joints, Faults, Other Fractures) Bedding Spacing (May Include Foliation or Banding)
Description Spacing Description Spacing
Extremely close < ¾ in (<19 mm) Laminated < ½ in (<12 mm)
Very close ¾ in – 2-1/2 in (19 - 60 mm) Very thin ½ in – 2 in (12 – 50 mm)
Close 2-1/2 in – 8 in (60 – 200 mm) Thin 2 in – 1 ft. (50 – 300 mm)
Moderate 8 in – 2 ft. (200 – 600 mm) Medium 1 ft. – 3 ft. (300 – 900 mm)
Wide 2 ft. – 6 ft. (600 mm – 2.0 m) Thick 3 ft. – 10 ft. (900 mm – 3 m)
Very Wide 6 ft. – 20 ft. (2.0 – 6 m) Massive > 10 ft. (3 m)
Discontinuity Orientation (Angle): Measure the angle of discontinuity relative to a plane perpendicular to the longitudinal axis of the
core. (For most cases, the core axis is vertical; therefore, the plane perpendicular to the core axis is horizontal.) For example, a
horizontal bedding plane would have a 0-degree angle.
ROCK QUALITY DESIGNATION (RQD) 1
Description RQD Value (%)
Very Poor 0 - 25
Poor 25 – 50
Fair 50 – 75
Good 75 – 90
Excellent 90 - 100
1. The combined length of all sound and intact core segments equal to or greater than 4 inches in length, expressed as a
percentage of the total core run length.
Reference: U.S. Department of Transportation, Federal Highway Administration, Publication No FHWA-NHI-10-034, December 2009
Technical Manual for Design and Construction of Road Tunnels – Civil Elements
Liquid limit - oven dried
0.75 OH
Organic clay K, L, M, P
Liquid limit - not dried Organic silt K, L, M, Q
Highly organic soils: Primarily organic matter, dark in color, and organic odor PT Peat
A Based on the material passing the 3-inch (75-mm) sieve.
B If field sample contained cobbles or boulders, or both, add “with cobbles
or boulders, or both” to group name.
C Gravels with 5 to 12% fines require dual symbols: GW-GM well-graded
gravel with silt, GW-GC well-graded gravel with clay, GP-GM poorly
graded gravel with silt, GP-GC poorly graded gravel with clay.
D Sands with 5 to 12% fines require dual symbols: SW-SM well-graded
sand with silt, SW-SC well-graded sand with clay, SP-SM poorly graded
sand with silt, SP-SC poorly graded sand with clay.
E Cu = D60/D10 Cc =
10 60
2
30
D x D
(D )
F If soil contains 15% sand, add “with sand” to group name.
G If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM.
H If fines are organic, add “with organic fines” to group name.
I If soil contains 15% gravel, add “with gravel” to group name.
J If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay.
K If soil contains 15 to 29% plus No. 200, add “with sand” or “with
gravel,” whichever is predominant.
L If soil contains 30% plus No. 200 predominantly sand, add
“sandy” to group name.
M If soil contains 30% plus No. 200, predominantly gravel, add
“gravelly” to group name.
N PI 4 and plots on or above “A” line.
O PI 4 or plots below “A” line.
P PI plots on or above “A” line.
Q PI plots below “A” line.
SAMPLING WATER LEVEL FIELD TESTS
GENERAL NOTES
DESCRIPTION OF SYMBOLS AND ABBREVIATIONS
Water levels indicated on the soil boring logs are
the levels measured in the borehole at the times
indicated. Groundwater level variations will occur
over time. In low permeability soils, accurate
determination of groundwater levels is not possible
with short term water level observations.
STRENGTH TERMS
30 - 50
> 50
5 - 9
10 - 18
Descriptive
Term
(Consistency)
8 - 15
> 30
Ring
Sampler
Blows/Ft.
10 - 29
> 99
Medium Hard
< 3
3 - 4
19 - 42
2 - 4
BEDROCK
Standard
Penetration
or N-Value
Blows/Ft.
Very Loose 0 - 3 Very Soft
(More than 50% retained on No. 200
sieve.)
Density determined by Standard
Penetration Resistance
(50% or more passing the No. 200 sieve.)
Consistency determined by laboratory shear strength testing,
field visual-manual procedures or standard penetration
resistance
RELATIVE DENSITY OF COARSE-GRAINED SOILS
30 - 49
50 - 79
>79
Descriptive
Term
(Consistency)
Firm
< 20 Weathered
Hard
< 30
30 - 49
50 - 89
90 - 119
15 - 30 > 119
Standard
Penetration or
N-Value
Blows/Ft.
0 - 1
4 - 8
Very Hard
Ring
Sampler
Blows/Ft.
Ring
Sampler
Blows/Ft.
Soft
Medium Stiff
Stiff
Very Stiff
Hard
CONSISTENCY OF FINE-GRAINED SOILS
Standard
Penetration
or N-Value
Blows/Ft.
> 42
Loose
Medium Dense
Dense
Very Dense
7 - 18
19 - 58
Descriptive Term
(Density)
0 - 6
4 - 9
59 - 98
_
20 - 29
2 - 3
9 - 10
12.5
11.8
B1
B2
61.4
58.1
2 - 3
9 - 10
9.3
11.0
29.3
30.9
25
19 0.094
Boring ID Depth WC (%) LL PL PI Cc Cu
Boring ID Depth D100 D60 D30 D10 %Gravel %Sand %Silt %Fines %Clay
USCS Classification
%Cobbles
0.0
0.0
FIELD TEST
RESULTS
SWELL/CONSOL
(%/psf)
UNCONFINED
COMPRESSIVE
STRENGTH (psf)
PERCENT FINES
DEPTH ELEVATION (Ft.)
Approximate Surface Elev.: 5002.2 (Ft.) +/-
Page 1 of 1
Advancement Method:
4-inch diameter soild-stem auger
Abandonment Method:
Boring backfilled with Auger Cuttings and/or Bentonite
Surface Capped with Asphalt
Notes:
Project No.: 20205071
Drill Rig: CME 55
BORING LOG NO. B2
CLIENT: Beta Tau 1919 Corporation
Denver, CO
Driller: Drilling Engineers, Inc.
Boring Completed: 07-24-2020
PROJECT: Beta Tau Fraternity House Addition
Elevations were measured in the field using an
engineer's level and grade rod.
See Exploration and Testing Procedures for a
description of field and laboratory procedures used
and additional data (If any).
See Supporting Information for explanation of
symbols and abbreviations.
1516 Remington Street
Fort Collins, CO
SITE:
Boring Started: 07-24-2020
1901 Sharp Point Dr Ste C
Fort Collins, CO
No free water encountered while drilling
No free water encountered after drilling
WATER LEVEL OBSERVATIONS
1
2
SAMPLE TYPE
Elevations were measured in the field using an
engineer's level and grade rod.
See Exploration and Testing Procedures for a
description of field and laboratory procedures used
and additional data (If any).
See Supporting Information for explanation of
symbols and abbreviations.
1516 Remington Street
Fort Collins, CO
SITE:
Boring Started: 07-24-2020
1901 Sharp Point Dr Ste C
Fort Collins, CO
No free water encountered while drilling
No free water encountered after drilling
WATER LEVEL OBSERVATIONS
1
SAMPLE TYPE
the existing and proposed building addition and pavements. Water should not be
allowed to pond adjacent to foundations or on pavements and conservative irrigation
practices should be followed to avoid wetting foundation/slab soils and pavement
subgrade. Excessive wetting of foundations/slab soils and subgrade can cause
movement and distress to foundations, floor slabs, concrete flatwork and pavements.