HomeMy WebLinkAboutJOHNSON DRIVE APARTMENTS - PDP - PDP170034 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTGeotechnical Engineering Report
255 Johnson Drive Project
255 Johnson Drive
Fort Collins, Colorado
September 8, 2017
Terracon Project No. 20175071
Prepared for:
Next Chapter Properties
Champaign, Illinois
Prepared by:
Terracon Consultants, Inc.
Fort Collins, Colorado
TABLE OF CONTENTS
EXECUTIVE SUMMARY ............................................................................................................ i
1.0 INTRODUCTION ............................................................................................................ 1
2.0 PROJECT INFORMATION ............................................................................................ 1
2.1 Project Description .............................................................................................. 1
2.2 Site Location and Description ............................................................................. 2
3.0 SUBSURFACE CONDITIONS ....................................................................................... 2
3.1 Typical Subsurface Profile .................................................................................. 2
3.2 Laboratory Testing .............................................................................................. 3
3.3 Groundwater Monitoring ...................................................................................... 3
4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION ..................................... 4
4.1 Geotechnical Considerations .............................................................................. 4
4.1.1 Existing, Undocumented Fill .................................................................... 4
4.1.2 Shallow Groundwater .............................................................................. 5
4.1.3 Expansive Soils ....................................................................................... 5
4.1.4 Foundation Recommendations ................................................................ 5
4.2 Earthwork ........................................................................................................... 5
4.2.1 Site Preparation........................................................................................ 6
4.2.2 Demolition ............................................................................................... 6
4.2.3 Excavation ............................................................................................... 6
4.2.4 Subgrade Preparation .............................................................................. 7
4.2.5 Fill Materials and Placement ..................................................................... 7
4.2.6 Compaction Requirements ....................................................................... 9
4.2.7 Utility Trench Backfill ............................................................................... 9
4.2.8 Grading and Drainage .............................................................................10
4.2.9 Exterior Slab Design and Construction ...................................................10
4.3 Foundations .......................................................................................................11
4.3.1 Drilled Piers Bottomed in Bedrock - Design Recommendations ..............11
4.3.2 Drilled Piers Bottomed in Bedrock - Construction Considerations ...........12
4.4 Seismic Considerations......................................................................................13
4.5 Floor Slabs and Parking Garage Slab ................................................................14
4.5.1 Floor System - Design Recommendations ..............................................14
4.5.2 Floor Systems - Construction Considerations .........................................15
4.6 Pavements .........................................................................................................15
4.6.1 Pavements – Subgrade Preparation .......................................................15
4.6.2 Pavements – Design Recommendations ................................................15
4.6.3 Pavements – Construction Considerations .............................................17
4.6.4 Pavements – Maintenance .....................................................................18
5.0 GENERAL COMMENTS ...............................................................................................19
TABLE OF CONTENTS (continued)
Appendix A – FIELD EXPLORATION
Exhibit A-1 Site Location Map
Exhibit A-2 Exploration Plan
Exhibit A-3 Field Exploration Description
Exhibits A-4 to A-9 Boring Logs
Appendix B – LABORATORY TESTING
Exhibit B-1 Laboratory Testing Description
Exhibit B-2 Atterberg Limits Test Results
Exhibits B-3 to B-4 Grain-size Distribution Test Results
Exhibits B-5 to B-6 Swell-consolidation Test Results
Exhibits B-7 to B-8 Unconfined Compression Test Results
Appendix C – SUPPORTING DOCUMENTS
Exhibit C-1 General Notes
Exhibit C-2 Unified Soil Classification System
Exhibit C-3 Description of Rock Properties
Geotechnical Engineering Report
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September 8, 2017 ■ Terracon Project No. 20175071
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EXECUTIVE SUMMARY
A geotechnical exploration has been performed for the proposed commercial/office space, two-
story parking area and pavements to be constructed at 255 Johnson Drive in Fort Collins,
Colorado. Six (6) borings, presented as Exhibits A-4 through A-9 and designated as Boring No. 1
through Boring No. 6, were performed to depths of approximately 30 feet below existing site grades.
This report specifically addresses the recommendations for the proposed structures and pavements.
Borings performed in these areas are for informational purposes and will be utilized by others.
Based on the information obtained from our subsurface exploration, the site can be developed for
the proposed project. However, the following geotechnical considerations were identified and will
need to be considered:
Existing, undocumented fill was encountered in the borings performed on this site to depths
ranging from about 1 to 9 feet below existing site grades. The existing fill soils should be
removed and replaced with engineered fill beneath proposed buildings.
Groundwater was encountered in the borings at depths of about 4 to 11 feet below the
existing pavement surface during and/or shortly after completion of drilling. Each of the six
boreholes were completed as monitoring wells to facilitate delayed groundwater
measurements. Groundwater levels can and should be expected to fluctuate with varying
seasonal and weather conditions, irrigation practices on or adjacent to the site and
fluctuations with nearby water features.
We recommend a slab-on-grade floor system for the proposed commercial/office space and
low level parking level provided the soils are over-excavated to a depth of at least 2 feet and
replaced with moisture conditioned, properly compacted engineered fill. The upper 12 inches
of over-excavation backfill should consist of Colorado Department of Transportation (CDOT)
Class 1 structure backfill.
Low strength and compressible soils are present on this site. We do not believe the
subsoils at and with the zone of influence of shallow foundations have adequate strength
to support anticipated loads with less than an inch of settlement. The proposed structure
may be supported on a drilled pier foundation system bottomed in bedrock. We believe
drilled piers would provide a reliable foundation system to mitigate post-construction
movement. Drilled piers will likely require temporary casing and a concrete pump truck
with tremie extension to properly construct piers. Heavy-duty drilling equipment will be
required to penetrate the very hard bedrock. Geotechnical recommendations and design
criteria for drilled pier foundations are presented in this report.
As an alternative to drilled pier foundations, consideration could be given to ground
modification/improvement techniques to improve strength and compressibility characteristics
pf the foundation soils to allow for support of the building on shallow foundations. One
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approach would include rammed aggregate-pier foundation elements or stone columns to
support shallow foundations. Aggregate-pier foundation elements are usually part of the
foundation contractor’s design-build system. Therefore, the subsurface exploration
information contained in this report should be provided to the foundation contractors for
detailed analysis and design and cost information.
Low strength native clay soils should be expected at some locations with the parking garage
excavation and these conditions will likely require some stabilization to provide adequate
support for construction equipment and slabs. Some subgrade stabilization should be
anticipated and budgeted for this project.
On-site soils free of vegetation, organic matter and other unsuitable materials or low volume
change import materials approved by Terracon may be used as fill/backfill material on the
site provided they are placed and compacted as described in this report. On-site sandstone
bedrock materials or cutting from pier excavations may be used as fill provided the material
is broken down and processed into a “soil-like” consistency. Import materials (if needed)
should be evaluated and approved by the geotechnical engineer prior to delivery to the site.
Surface drainage should be designed, constructed and maintained to provide rapid removal
of surface water runoff away from the proposed building. Water should not be allowed to
pond adjacent to foundations or exterior slabs and conservative irrigation practices should
be followed to avoid wetting the subsoils. 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 4.2.8 Grading and Drainage section
of this report be followed to reduce potential movement.
According to Table 30.3-1 of ASCE 7-10 seismic site classification for this site is C.
Close monitoring of the construction operations discussed herein will be critical in achieving
the design subgrade support. We therefore recommend that Terracon be retained to
monitor this portion of the work.
This summary should be used in conjunction with the entire report for design purposes. It should
be recognized that 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. The section
titled GENERAL COMMENTS should be read for an understanding of the report limitations.
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GEOTECHNICAL ENGINEERING REPORT
255 Johnson Drive Project
255 Johnson Drive
Fort Collins, Colorado
Terracon Project No. 20175071
September 8, 2017
1.0 INTRODUCTION
This report presents the results of our geotechnical engineering services performed for the
proposed project to be located at 255 Johnson Drive in Fort Collins, Colorado (Exhibit A-1). The
purpose of these services is to provide information and geotechnical engineering
recommendations relative to:
subsurface soil and bedrock conditions foundation design and construction
groundwater conditions seismic considerations
grading and drainage pavement construction
lateral earth pressures earthwork
Our geotechnical engineering scope of work for this project included the initial site visit, the
advancement of six test borings to depths approximately 30 feet below existing site grades,
laboratory testing for soil engineering properties and engineering analyses to provide foundation,
pavement design and construction recommendations.
Logs of the borings along with an Exploration Plan (Exhibit A-2) are included in Appendix A. The
results of the laboratory testing performed on soil and bedrock samples obtained from the site
during the field exploration are included in Appendix B.
2.0 PROJECT INFORMATION
2.1 Project Description
Item Description
Site layout Refer to the Exploration Plan (Exhibit A-2 in Appendix A)
Structures
The project will include an approximately 6,640 square foot
commercial/office space as well as a two-story parking area, drives
lanes and landscaped areas.
Building construction
We anticipate the parking garage will be constructed of reinforced,
precast concrete.
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Item Description
Maximum loads
Parking garage:
Columns – 200 to 300 kips (assumed)
Continuous Load-Bearing Wall Loads – 2 to 5 klf (assumed)
Load conditions were not provided at this time this report was
written.
Grading in building area
Considering the existing concrete pavements will be preserved
where reasonable, minor grading will be necessary to complete the
project. We anticipate cuts and fills on the order of about 2 to 3 feet
will be necessary to construct new foundation elements.
Below-grade areas No below-grade areas are planned.
2.2 Site Location and Description
Item Description
Parcel information
The project site is located at 255 Johnson Drive in Fort Collins,
Colorado and covers approximately 1.5 acres (See Site Location).
Approximate GPS Coordinates for the center of the site are
40.56156° N/105.07870° W.
Existing improvements
The site is currently developed as a storage facility comprised of
five one-story buildings. The majority of the site that is outside the
footprint of the buildings is paved with asphalt. A retaining wall
rises approximately 30 feet high on the western border of the site.
Current ground cover Asphalt pavement and storage facilities.
Existing topography The site is relatively flat.
3.0 SUBSURFACE CONDITIONS
3.1 Typical Subsurface Profile
Specific conditions encountered at each boring location are indicated on the individual boring logs
included in Appendix A. Stratification boundaries on the boring logs represent the approximate
location of changes in soil types; in-situ, the transition between materials may be gradual. Based
on the results of the borings, subsurface conditions on the project site can be generalized as
follows:
Material Description
Approximate Depth to
Bottom of Stratum
Consistency/Density/Hardness
Existing asphalt pavement About 1½ to 7 inches thick N/A
Existing aggregate base course About 1 to 2 inches thick N/A
Undocumented fill 9 Stiff
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Material Description
Approximate Depth to
Bottom of Stratum
Consistency/Density/Hardness
Silt and/or clay with varying
amounts of sand
About 3 to 13 feet below
existing site grades.
Medium stiff to stiff
Poorly graded sand and/or gravel About 4½ to 19 feet below
existing site grades.
Medium dense to dense
Sandstone bedrock
To the maximum depth of
exploration of about 30 feet.
Weathered to very hard
3.2 Laboratory Testing
Representative soil samples were selected for swell-consolidation testing and exhibited 0.1 to 0.3
percent compression when wetted. The sandstone bedrock is also considered to be non-
expansive. Two samples of bedrock soils exhibited unconfined compressive strengths of
approximately 160 and 520 pounds per square foot (psf); however, these samples were very
granular and the test results may not have been representative of strength characteristics of these
materials. Samples of site soils and bedrock selected for plasticity testing exhibited low to
moderate plasticity with liquid limits ranging from non-plastic to 43 and plasticity indices ranging
from non-plastic to 43. Laboratory test results are presented in Appendix B.
3.3 Groundwater Monitoring
We understand the project team wants to obtain information about groundwater depths and
elevations to consider during development of the project. We have completed the boreholes as
groundwater monitoring wells to facilitate groundwater monitoring. We removed the auger cuttings
from the site. Monitoring wells were constructed as follows:
Installation of a minimum of 5 feet of 2-inch diameter, 0.010-inch machine slotted polyvinyl
chloride (PVC) well screen with a threaded bottom cap
Installation of 2-inch diameter, threaded, flush joint PVC riser pipe to surface
Addition of pre-sieved 20/40 grade silica sand for annular sand pack around the well
screen from the bottom of the boring to approximately 2 feet above the top of the well
screen
Placement of 2 feet of hydrated bentonite pellets above the sand pack
Installation of flush-mounted well cap set in concrete
Following initial groundwater measurements, Terracon will return to the project site on an as-request
or as-scheduled basis to measure groundwater levels in each of the monitoring wells. We will
prepare an updated report presenting each groundwater monitoring event to be used by the project
design team. We will present our groundwater measurements as depth to groundwater below the
existing site grades and elevation of groundwater.
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The boreholes were observed while drilling and after completion for the presence and level of
groundwater. In addition, delayed water levels were also obtained in all borings. The water levels
observed in the boreholes are noted on the attached boring logs, and are summarized below
Boring Number
Depth to groundwater while
drilling, ft.
Depth to groundwater 11
days after drilling, ft.
1 8 9
2 8 9
3 6 9
4 8 9
5 4 5
6 11 8
These observations represent groundwater conditions at the time of the field exploration, and may
not be indicative of other times or at other locations. Groundwater levels can be expected to
fluctuate with varying seasonal and weather conditions, and other factors.
Groundwater level fluctuations occur due to seasonal variations in the water levels present in
Spring Creek, amount of rainfall, runoff and other factors not evident at the time the borings were
performed. Therefore, groundwater levels during construction or at other times in the life of the
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 project.
4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION
4.1 Geotechnical Considerations
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. We have identified
geotechnical conditions that could impact design and construction of the proposed structure,
pavements, and other site improvements.
4.1.1 Existing, Undocumented Fill
As previously noted, existing undocumented fill was encountered at a depth of about 9 feet in
Boring No. 1 drilled at the site. We do not possess any information regarding whether the fill was
placed under the observation of a geotechnical engineer.
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Support of foundations, floor slabs, and pavements on or above existing fill soils is discussed in
this report. There is an inherent risk for the owner that compressible fill or unsuitable material
within or buried by the fill will not be discovered.
4.1.2 Shallow Groundwater
As previously stated, groundwater was measured at depths ranging from about 4 to 11 feet below
existing site grades which is consistent with groundwater conditions encountered during previous
studies at nearby project sites. Terracon recommends maintaining a separation of at least 3 feet
between the bottom of proposed floor slabs and measured groundwater levels. It is also possible
and likely that groundwater levels below this site may rise as water levels in the Spring Creek rise.
4.1.3 Expansive Soils
Laboratory testing indicates the native clay soils and exhibited low expansive potential at the
samples in-situ moisture content. However, it is our opinion these materials will exhibit a higher
expansive potential if the clays undergo a significant loss of moisture.
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 should be anticipated. The severity of cracking and other
damage such as uneven floor slabs will probably increase if any modification of the site results in
excessive wetting or drying of the expansive clays. Eliminating the risk of movement and 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 4.2.8 Grading and Drainage of this report be followed to
reduce movement.
4.1.4 Foundation Recommendations
The proposed building may be supported on a drilled pier system bearing bedrock. We
recommend a slab-on-grade floor system for the proposed commercial/office space and low level
parking level provided the soils are over-excavated to a depth of at least 2 feet and replaced with
moisture conditioned, properly compacted engineered fill. The upper 12 inches of over-excavation
backfill should consist of Colorado Department of Transportation (CDOT) Class 1 structure backfill.
Even when bearing on properly prepared soils, movement of the foundation system is possible
should the subgrade soils undergo an increase in moisture content. We estimate movement of
about 1 inch is possible. If the owner cannot accept the risk of slab movement, a structural floor
should be used.
4.2 Earthwork
The following presents recommendations for site preparation, excavation, subgrade preparation
and placement of engineered fills on the project. All earthwork on the project should be observed
and evaluated by Terracon on a full-time basis. The evaluation of earthwork should include
observation of over-excavation operations, testing of engineered fills, subgrade preparation,
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subgrade stabilization, and other geotechnical conditions exposed during the construction of the
project.
4.2.1 Site Preparation
Prior to placing any fill, strip and remove existing vegetation, the recommended depth of
undocumented existing fill, and any other deleterious materials from the proposed construction
areas. The undocumented fill extends to an approximate depth of 9 feet below the existing ground
surface.
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 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.
4.2.2 Demolition
Demolition of the existing storage unit complex 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 storage unit complex are not known. If some or
all of the existing buildings are supported by drilled piers, the existing piers should be truncated a
minimum depth of 3 feet below areas of planned new construction.
Consideration could be given to re-using the asphalt 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.
4.2.3 Excavation
It is anticipated that excavations for the proposed construction can be accomplished with
conventional earthmoving equipment. However, due to high blow counts on some of the bedrock
encountered, it is possible that a heavy duty drill rig and/or core barrels will be necessary for drilled
pier excavation.
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 underground facilities such as septic tanks, vaults, and basements, was not
observed during the site reconnaissance, such features could be encountered during construction.
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If unexpected underground facilities are encountered, such features should be removed and the
excavation thoroughly cleaned prior to backfill placement and/or construction.
Depending upon depth of excavation and seasonal conditions, surface water infiltration and/or
groundwater may be encountered in excavations on the site. It is anticipated that pumping from
sumps may be utilized to control water within excavations.
The subgrade soil conditions should be evaluated during the excavation process and the stability
of the soils determined at that time by the contractors’ Competent Person. Slope inclinations flatter
than the OSHA maximum values may have to be used. The individual contractor(s) should be
made responsible for designing and constructing stable, temporary excavations as required to
maintain stability of both the excavation sides and bottom. All excavations should be sloped or
shored in the interest of safety following local, and federal regulations, including current OSHA
excavation and trench safety standards.
As a safety measure, it is recommended that all vehicles and soil piles be kept a minimum lateral
distance from the crest of the slope equal to the slope height. The exposed slope face should be
protected against the elements
4.2.4 Subgrade Preparation
After the undocumented existing fill has been removed from the area and completion of the
recommended over-excavation before floor slabs, the top 8 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, slab or pavement is placed.
After the bottom of the excavation has been compacted, engineered fill can be placed to bring the
building pad and pavement subgrade to the desired grade. Engineered fill should be placed in
accordance with the recommendations presented in subsequent sections of this report.
The stability of the subgrade may be affected by precipitation, repetitive construction traffic or
other factors. If unstable conditions develop, workability may be improved by scarifying and
drying. Alternatively, over-excavation of wet zones and replacement with granular materials may
be used, or crushed gravel and/or rock can be tracked or “crowded” into the unstable surface soil
until a stable working surface is attained. Lightweight excavation equipment may also be used to
reduce subgrade pumping.
4.2.5 Fill Materials and Placement
The on-site soils or approved granular and low plasticity cohesive imported materials may be used
as fill material. We recommend the upper 12 inches of over-excavated backfill below the proposed
floor slabs consist of CDOT Class 1 structure backfill. The soil removed from this site that is free
of organic or objectionable materials, as defined by a field technician who is qualified in soil
material identification and compaction procedures, can be re-used as fill for the building pad and
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pavement subgrade. It should be noted that on-site will require reworking to adjust the moisture
content to meet the compaction criteria.
CDOT Class 1 structure backfill should meet the following material property requirements:
Gradation Percent finer by weight (ASTM C136)
2” 100
No. 4 Sieve 30-100
No. 50 Sieve 10-60
No. 200 Sieve 5-20
Soil Properties Values
Liquid Limit 35 (max.)
Plastic Limit 6 (max.)
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 15-50
Soil Properties Values
Liquid Limit 35 (max.)
Plastic Limit 6 (max.)
Maximum Expansive Potential (%) Non-expansive1
1. Measured on a sample compacted to approximately 95 percent of the maximum dry unit weight as
determined by ASTM D698 at optimum moisture content. The sample is confined under a 100 psf
surcharge and submerged.
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4.2.6 Compaction Requirements
Engineered fill should be placed and compacted in horizontal lifts, using equipment and
procedures that will produce recommended moisture contents and densities throughout the lift.
Item Description
Fill lift thickness
9 inches or less in loose thickness when heavy, self-
propelled compaction equipment is used
4 to 6 inches in loose thickness when hand-guided
equipment (i.e. jumping jack or plate compactor) is used
Minimum compaction requirements
95 percent of the maximum dry unit weight as determined
by ASTM D698
Moisture content cohesive soil (clay) -1 to +3 % of the optimum moisture content
Moisture content cohesionless soil
(sand)
Near 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 proofrolled.
3. Moisture conditioned clay materials should not be allowed to dry out. A loss of moisture within these
materials could result in an increase in the material’s expansive potential. Subsequent wetting of
these materials could result in undesirable movement.
4.2.7 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 structure should be effectively sealed to restrict water intrusion and flow
through the trenches that could migrate below the structure. We recommend constructing an
effective clay “trench plug” that extends at least 5 feet out from the face of the building exterior. The
plug material should consist of clay compacted at a water content at or above the soil’s optimum
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water content. The clay fill should be placed to completely surround the utility line and be compacted
in accordance with recommendations in this report.
It is strongly recommended that a representative of Terracon provide full-time observation and
compaction testing of trench backfill within building and pavement areas.
4.2.8 Grading and Drainage
All grades must be adjusted to provide effective drainage away from the proposed parking garage
and existing pavements 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 structure (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 building, where possible. The use of swales, chases and/or
area drains may be required to facilitate drainage in unpaved areas around the perimeter of the
building. 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 building 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
structure, care should be taken that joints are properly sealed and maintained to prevent the
infiltration of surface water.
Planters located adjacent to the structure 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 structure 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 or to a detention pond or other appropriate
outfall.
4.2.9 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:
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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.
4.3 Foundations
Low strength and compressible clay soils and existing fill are present on this site. Based on
assumed foundation loads, we anticipated total settlement on the order of about 1 ½ to 2 ½ inches
or more. Therefore, it is our opinion shallow foundations bearing on the site soils are not feasible
for support of the proposed building. Based on this information and the geotechnical data, we
believe straight shaft piers socketed into bedrock are appropriate for support of the building and
would provide a reliable foundation system to mitigate post-construction movement and distress.
As an alternative to drilled pier foundations, consideration would be given to ground
modification/improvement techniques to improve strength and compressibility characteristics of
the foundation soils and to allow for support of the structure on shallow foundations. One approach
would include rammed aggregate-pier foundation elements or stone columns to support shallow
foundations. Stone columns and rammed aggregate piers consist of a series of drilled holes filled
with highly compacted, well graded aggregate to form very stiff, high-density aggregate piers.
The stone column and rammed aggregate piers are generally extended below the low strength
soil layer to a layer of higher bearing capacity soils or bedrock. Installation of these elements
results in significant strengthening and stiffening of the foundation bearing layer to support
footings within typical settlement tolerances. Shallow foundations are then constructed over the
piers/columns in a conventional manner. Aggregate-pier foundation elements are usually part of
the contractor’s design-build system. Therefore, the subsurface exploration information contained
in this report should be provided to the foundation contractors for detailed analysis and design
and cost information.
Design recommendations for foundations for the proposed commercial/office space, two-story
parking area and related structural elements are presented in the following sections.
4.3.1 Drilled Piers Bottomed in Bedrock - Design Recommendations
Description Drilled Pier Design Parameter
Pier bearing stratum Unweathered sandstone bedrock
Minimum pier length 20 feet
Minimum pier diameter 18 inches
Minimum bedrock embedment 1 6 feet
Maximum allowable end-bearing pressure 40,000 psf
Geotechnical Engineering Report
255 Johnson Drive ■ Fort Collins, Colorado
September 8, 2017■ Terracon Project No. 20175071
Responsive ■ Resourceful ■ Reliable 12
Description Drilled Pier Design Parameter
Allowable skin friction (for portion of pier embedded
into bedrock)
2,500 psf
Void thickness (beneath grade beams) 4 inches
1. Drilled piers should be embedded into hard or very hard bedrock materials. Actual structural
loads and pier diameters may dictate embedment deeper than the recommended minimum
penetration.
Piers should be considered to work in group action if the horizontal spacing is less than three pier
diameters. A minimum practical horizontal clear spacing between piers of at least three diameters
should be maintained, and adjacent piers should bear at the same elevation. The capacity of
individual piers must be reduced when considering the effects of group action. Capacity reduction
is a function of pier spacing and the number of piers within a group. If group action analyses are
necessary, capacity reduction factors can be provided for the analyses.
To satisfy forces in the horizontal direction using LPILE, piers may be designed for the following
lateral load criteria:
Parameters
Clay and
Silt
Sand and
Gravel
Sandstone
Bedrock
LPILE soil type
Stiff clay
without free
water
(Reese)
Sand
(Reese)
Sand
(Reese)
Effective unit weight (pcf) above groundwater 110 115 120
Effective unit weight (pcf) below groundwater 50 55 60
Average undrained shear strength (psf) 750 N/A N/A
Average angle of internal friction, (degrees) N/A 33 38
Coefficient of subgrade reaction above
groundwater, k (pci)*
N/A 150 225
Coefficient of subgrade reaction below
groundwater, k (pci)*
N/A 100 125
Strain, 50 (%) 0.010 N/A N/A
1. For purposes of LPILE analysis, assume a groundwater depth of about 8 feet below existing ground
surface.
4.3.2 Drilled Piers Bottomed in Bedrock - Construction Considerations
With the exception of the upper part, the bedrock is very hard on this site. Large heavy-duty drill
rigs in good working condition will be required to facilitate the required bedrock penetration and pier
length. Our experience in the area indicates the bedrock can normally be penetrated with typical
auger drill methods. However, it is possible cemented zones or layers could be encountered during
Geotechnical Engineering Report
255 Johnson Drive ■ Fort Collins, Colorado
September 8, 2017■ Terracon Project No. 20175071
Responsive ■ Resourceful ■ Reliable 13
drilling and may require the use of a “rock bit” or rock coring to penetrate these materials. We noted
no indication of this condition at our boring locations during drilling but have similar experience
during construction of nearby projects.
Groundwater/caving soil conditions indicate that temporary steel casing may be required to
properly drill and clean piers prior to concrete placement. Groundwater should be removed from
each pier hole prior to concrete placement. Pier concrete should be placed immediately after
completion of drilling and cleaning. If pier concrete cannot be placed in dry conditions, a tremie
should be used for concrete placement. Free-fall concrete placement in piers will only be
acceptable if provisions are taken to avoid striking the concrete on the sides of the hole or
reinforcing steel. The use of a bottom-dump hopper, or an elephant's trunk discharging near the
bottom of the hole where concrete segregation will be minimized, is recommended. Due to
potential sloughing and raveling, foundation concrete quantities may exceed calculated geometric
volumes.
Casing should be withdrawn in a slow continuous manner maintaining a sufficient head of
concrete to prevent infiltration of water or caving soils or the creation of voids in pier concrete.
Pier concrete should have a relatively high fluidity when placed in cased pier holes or through a
tremie. Pier concrete with slump in the range of 5 to 7 inches is recommended.
We recommend the sides of each pier should be mechanically roughened in the sandstone
bearing strata. This should be accomplished by a roughening tooth placed on the auger. Shaft
bearing surfaces must be cleaned prior to concrete placement. A representative of Terracon
should observe the bearing surface and shaft configuration.
4.4 Seismic Considerations
Code Used Site Classification
Table 20.3-1 of ASCE 7-10 1 C 2
1. Table 20.3-1 of ASCE 7-10 requires a site soil profile determination extending a depth of 100 feet
for seismic site classification. The current scope requested does not include the required 100 foot
soil profile determination. The borings completed for this project extended to a maximum depth of
about 30 feet and this seismic site class definition considers that similar soil and bedrock conditions
exist below the maximum depth of the subsurface exploration. Additional exploration to deeper
depths could be performed to confirm the conditions below the current depth of exploration.
Alternatively, a geophysical exploration could be utilized in order to attempt to justify a more favorable
seismic site class. However, we believe a higher seismic site class for this site is unlikely.
Geotechnical Engineering Report
255 Johnson Drive ■ Fort Collins, Colorado
September 8, 2017■ Terracon Project No. 20175071
Responsive ■ Resourceful ■ Reliable 14
4.5 Floor Slabs and Parking Garage Slab
Low strength native clay soils should be expected at some locations within the parking garage
excavations and these conditions will require some stabilization to provide adequate support for
construction equipment and slabs. Some subgrade stabilization should be anticipated and
budgeted for this project. Details how the subgrade soils should be prepared are presented in the
4.2 Earthwork section of this report.
We recommend a slab-on-grade floor system for the proposed commercial/office space and low level
parking level provided the soils are over-excavated to a depth of at least 2 feet and replaced with
moisture conditioned, properly compacted engineered fill. The upper 12 inches of over-excavation
backfill should consist of Colorado Department of Transportation (CDOT) Class 1 structure backfill.
We recommend proof rolling the subgrade exposed at the base of the over-excavation to help
identify any potentially soft/loose or unstable areas that will require reworking or stabilization prior
to placing any over-excavation backfill. After remedial earthwork has been completed, we believe
a conventional slab-on-grade floor could be used provided some movement can be tolerated.
4.5.1 Floor System - Design Recommendations
For structural design of concrete slabs-on-grade subjected to point loadings, a modulus of
subgrade reaction of 200 pounds per cubic inch (pci) may be used for floors supported on on at
least 1 foot of non-expansive, imported CDOT Class 1 structure backfill.
Additional floor slab design and construction recommendations are as follows:
Positive separations and/or isolation joints should be provided between slabs and all
foundations, columns, or utility lines to allow independent movement.
Control joints should be saw-cut in slabs in accordance with ACI Design Manual, Section
302.1R-37 8.3.12 (tooled control joints are not recommended) to control the location and
extent of cracking.
Interior utility trench backfill placed beneath slabs should be compacted in accordance
with the recommendations presented in the 4.2 Earthwork section of this report.
Floor slabs should not be constructed on frozen subgrade.
The use of a vapor retarder should be considered beneath concrete slabs that will be
covered with wood, tile, carpet or other moisture sensitive or impervious floor coverings,
or when the slab will support equipment sensitive to moisture. When conditions warrant
the use of a vapor retarder, the slab designer and slab contractor should refer to ACI
302 for procedures and cautions regarding the use and placement of a vapor retarder.
Geotechnical Engineering Report
255 Johnson Drive ■ Fort Collins, Colorado
September 8, 2017■ Terracon Project No. 20175071
Responsive ■ Resourceful ■ Reliable 15
Other design and construction considerations, as outlined in the ACI Design Manual,
Section 302.1R are recommended.
4.5.2 Floor Systems - Construction Considerations
Movements of slabs-on-grade using the recommendations discussed in previous sections of this
report will likely be reduced and tend to be more uniform. The estimates discussed above assume
that the other recommendations in this report are followed. Additional movement could occur
should the subsurface soils become wetted to significant depths, which could result in potential
excessive movement causing uneven floor slabs and severe cracking. This could be due to over
watering of landscaping, poor drainage, improperly functioning drain systems, and/or broken utility
lines. Therefore, it is imperative that the recommendations presented in this report be followed.
4.6 Pavements
4.6.1 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 proofrolled 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.
4.6.2 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
Class II – Parking lots with a maximum of 10 trucks per day with Equivalent
Single Axle Load (ESAL) up to 27,000 over 20 years (Including trash trucks)
Subgrade Soil Characteristics
USCS Classification – ML or 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):
Geotechnical Engineering Report
255 Johnson Drive ■ Fort Collins, Colorado
September 8, 2017■ Terracon Project No. 20175071
Responsive ■ Resourceful ■ Reliable 16
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 – ML or 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 4½ 6 - 10½
B - - 6 6
Aggregate base course (if used on the site) should consist of a blend of sand and gravel which
meets strict specifications for quality and gradation. Use of materials meeting Colorado
Department of Transportation (CDOT) Class 5 or 6 specifications is recommended for aggregate
base course. Aggregate base course should be placed in lifts not exceeding 6 inches and
compacted to a minimum of 95 percent of the maximum dry unit weight as determined by ASTM
D698.
Asphaltic concrete should be composed of a mixture of aggregate, filler and additives (if required)
and approved bituminous material. The asphalt concrete should conform to approved mix
designs stating the Superpave properties, optimum asphalt content, job mix formula and
recommended mixing and placing temperatures. Aggregate used in asphalt concrete should
meet particular gradations. Material meeting CDOT Grading S or SX specifications or equivalent
is recommended for asphalt concrete. Mix designs should be submitted prior to construction to
verify their adequacy. Asphalt material should be placed in maximum 3-inch lifts and compacted
within a range of 92 to 96 percent of the theoretical maximum (Rice) density (ASTM D2041).
Where rigid pavements are used, the concrete should be produced from an approved mix design
with the following minimum properties:
Geotechnical Engineering Report
255 Johnson Drive ■ Fort Collins, Colorado
September 8, 2017■ Terracon Project No. 20175071
Responsive ■ Resourceful ■ Reliable 17
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
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 proofrolled. 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;
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.
4.6.3 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.
Geotechnical Engineering Report
255 Johnson Drive ■ Fort Collins, Colorado
September 8, 2017■ Terracon Project No. 20175071
Responsive ■ Resourceful ■ Reliable 18
4.6.4 Pavements – Maintenance
Preventative maintenance should be planned and provided for an ongoing pavement
management program in order to enhance future pavement performance. Preventive
maintenance consists of both localized maintenance (e.g. crack and joint sealing and patching)
and global maintenance (e.g. surface sealing). Preventative maintenance is usually the first
priority when implementing a planned pavement maintenance program and provides the highest
return on investment for pavements.
Geotechnical Engineering Report
255 Johnson Drive ■ Fort Collins, Colorado
September 8, 2017■ Terracon Project No. 20175071
Responsive ■ Resourceful ■ Reliable 19
5.0 GENERAL COMMENTS
Terracon should be retained to review the final design plans and specifications so comments can
be made regarding interpretation and implementation of our geotechnical recommendations in
the design and specifications. Terracon also should be retained to provide observation and testing
services during grading, excavation, foundation construction and other earth-related construction
phases of the project.
The analysis and recommendations presented in this report are based upon the data obtained
from the borings performed at the indicated locations and from other information discussed in this
report. This report does not reflect variations that may occur between borings, across the site, 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. If variations appear, we should be
immediately notified so that further evaluation and supplemental recommendations can be
provided.
The scope of services for this project does not include either specifically or by implication any
environmental or biological (e.g., mold, fungi, and 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.
This report has been prepared for the exclusive use of our client for specific application to the
project discussed and has been prepared in accordance with generally accepted geotechnical
engineering practices. No warranties, either express or implied, are intended or made. Site
safety, excavation support, and dewatering requirements are the responsibility of others. In the
event that changes in the nature, design, or location of the project as described in this report are
planned, the conclusions and recommendations contained in this report shall not be considered
valid unless Terracon reviews the changes and either verifies or modifies the conclusions of this
report in writing.
APPENDIX A
FIELD EXPLORATION
SITE LOCATION MAP
255 Johnson Drive
255 Johnson Drive
Fort Collins, Colorado
TOPOGRAPHIC MAP IMAGE COURTESY OF THE U.S. GEOLOGICAL SURVEY
QUADRANGLES INCLUDE: FORT COLLINS, CO (1984).
1901 Sharp Point Dr Ste C
Fort Collins, CO
20175071
Project Manager:
Drawn by:
Checked by:
Approved by:
RSG
EDB
EDB
1”=2,000’
09/08/2017
Project No.
Scale:
File Name:
Date: A-1
EDB Exhibit
SITE
South College Avenue
Johnson Drive
Spring Court
EXPLORATION PLAN
255 Johnson Drive
255 Johnson Drive
Fort Collins, Colorado
1901 Sharp Point Dr Ste C
Fort Collins, CO
DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS
NOT INTENDED FOR CONSTRUCTION PURPOSES
E2135001
AERIAL PHOTOGRAPHY PROVIDED
BY MICROSOFT BING MAPS
RSG
EDB
EDB
AS SHOWN
09/08/2017
Scale:
A-2
Project Manager: Exhibit
Drawn by:
Checked by:
Approved by:
Project No.
File Name:
Date:
EDB
Geotechnical Engineering Report
255 Johnson Drive ■ Fort Collins, Colorado
September 8, 2017■ Terracon Project No. 20175071
Responsive ■ Resourceful ■ Reliable Exhibit A-3
Field Exploration Description
The locations of borings were based upon the proposed development shown on the provided site
plan. The borings were located in the field by measuring from existing site features.
The borings were drilled with a CME-55 truck-mounted rotary drill rig with solid-stem augers.
During the drilling operations, lithologic logs of the borings were recorded by the field engineer.
Disturbed samples were obtained at selected intervals utilizing a 2-inch outside diameter split-
spoon sampler and a 3-inch outside diameter ring-barrel sampler. Penetration resistance values
were recorded in a manner similar to the standard penetration test (SPT). This test consists of
driving the sampler into the ground with a 140-pound hammer free-falling through a distance of
30 inches. The number of blows required to advance the ring-barrel sampler 12 inches (18 inches
for standard split-spoon samplers, final 12 inches are recorded) or the interval indicated, is
recorded as a standard penetration resistance value (N-value). The blow count values are
indicated on the boring logs at the respective sample depths. Ring-barrel sample blow counts are
not considered N-values.
A CME cathead and rope SPT hammer was used to advance the samplers in the borings performed
on this site. The standard penetration test provides a reasonable indication of the in-place density
of sandy type materials, but only provides an indication of the relative stiffness of cohesive
materials since the blow count in these soils may be affected by the moisture content of the soil.
In addition, considerable care should be exercised in interpreting the N-values in gravelly soils,
particularly where the size of the gravel particle exceeds the inside diameter of the sampler.
Groundwater measurements were obtained in the borings at the time of site exploration. After
completion of drilling, the borings were completed as monitoring wells.
0.6
0.7
9.0
29.1
ASPHALT, 7 inches
AGGREGATE BASE COURSE, 1 inch
FILL - SANDY SILT , red brown, medium
stiff to stiff, fill thickness was difficult to
delineate
SEDIMENTARY BEDROCK -
SANDSTONE, brown, light grey at about
17', very hard
Boring Terminated at 29.1 Feet
18
21
22
25
27
22
100
NP
NP
NP
54
15
24
Top cap
Cement seal
above
bentonite seal
Bentonite chips
with riser pipe
Solid pipe in
sand
Screen pack in
sand
5-6
3-3-4
N=7
10-24
50/6"
50/4"
50/1"
Stratification lines are approximate. In-situ, the transition may be gradual.
DEPTH
LOCATION: See Exhibit A-2
GRAPHIC LOG
Hammer Type: Rope and Cathead
Latitude: 40.56192° Longitude: -105.0792°
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-WELL 20175071 255 JOHNSON DRIVE.GPJ TERRACON_DATATEMPLATE.GDT 9/8/17
SWELL- CONSOL
/LOAD
(%/psf)
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
0.1
0.3
9.0
19.0
29.0
ASPHALT, 1.5 inches
AGGREGATE BASE COURSE, 1.5
inches
SILT WITH SAND, brown, stiff to very
stiff
POORLY GRADED GRAVEL WITH
SILT AND SAND, brown, dense
SEDIMENTARY BEDROCK -
SANDSTONE, weathered, light gray, very
hard
Boring Terminated at 29 Feet
+0.1/1000
15
21
13
7
22
26
102 NP
NP
74
6
Top cap
Cement seal
above
bentonite seal
Bentonite chips
with riser pipe
Solid pipe in
sand
Screen pack in
sand
10-9-11
N=20
14-10
16-17-25
N=42
15-31
50/6"
50/3"
50/bounce
Stratification lines are approximate. In-situ, the transition may be gradual.
DEPTH
LOCATION: See Exhibit A-2
GRAPHIC LOG
Hammer Type: Rope and Cathead
Latitude: 40.56175° Longitude: -105.07842°
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-WELL 20175071 255 JOHNSON DRIVE.GPJ TERRACON_DATATEMPLATE.GDT 9/8/17
SWELL- CONSOL
/LOAD
(%/psf)
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
0.3
0.4
13.0
18.0
29.2
ASPHALT, 3 inches
AGGREGATE BASE COURSE, 2 inches
SANDY LEAN CLAY, brown to reddish
brown, medium stiff
POORLY GRADED SAND, brown, dense
SEDIMENTARY BEDROCK -
SANDSTONE, brown, very hard
Boring Terminated at 29.2 Feet
15
16
24
23
21
23
26-18-8 67
Top cap
Cement seal
above
bentonite seal
Bentonite chips
with riser pipe
Screen pack in
sand
3-2-3
N=5
3-5
3-3-4
N=7
20-23-15
N=38
30 - 50/5"
50/2"
Stratification lines are approximate. In-situ, the transition may be gradual.
DEPTH
LOCATION: See Exhibit A-2
GRAPHIC LOG
Hammer Type: Rope and Cathead
Latitude: 40.56162° Longitude: -105.07887°
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-WELL 20175071 255 JOHNSON DRIVE.GPJ TERRACON_DATATEMPLATE.GDT 9/8/17
SWELL- CONSOL
/LOAD
(%/psf)
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
PERCENT FINES
WATER LEVEL
OBSERVATIONS
SAMPLE TYPE
DEPTH (Ft.)
5
0.4
0.6
3.0
9.0
13.0
29.0
ASPHALT, 5 inches
AGGREGATE BASE COURSE, 2 inches
SILTY CLAY, red and brown, medium
stiff
CLAYEY SAND, dark brown, loose to
medium dense
SEDIMENTARY BEDROCK -
SANDSTONE, light brown, medium hard,
weathered
SEDIMENTARY BEDROCK -
SANDSTONE, brown, light gray at 27',
very hard
Boring Terminated at 29 Feet
+0.3/150 15
21
22
24
21
114
101
30-16-14 44
Top cap
Cement seal
above
bentonite seal
Bentonite chips
with riser pipe
Solid pipe in
sand
Screen pack in
sand
3-4
2-2-4
N=6
5-9
50/2"
50/2"
50/bounce
Stratification lines are approximate. In-situ, the transition may be gradual.
DEPTH
LOCATION: See Exhibit A-2
GRAPHIC LOG
Hammer Type: Rope and Cathead
Latitude: 40.5612° Longitude: -105.07841°
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-WELL 20175071 255 JOHNSON DRIVE.GPJ TERRACON_DATATEMPLATE.GDT 9/8/17
SWELL- CONSOL
/LOAD
(%/psf)
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
0.4
0.6
4.5
29.0
ASPHALT, 5 inches
AGGREGATE BASE COURSE, 2 inches
POORLY GRADED GRAVEL WITH
SILT AND SAND, brown, medium dense
to dense
SEDIMENTARY BEDROCK -
SANDSTONE, brown, light gray at 17',
very hard, piece of granite at about 5'
Boring Terminated at 29 Feet
15
17
22
19
20
Top cap
Cement seal
above
bentonite seal
Bentonite chips
with riser pipe
Screen pack in
sand
12-22
50/6"
50/2"
50/4"
50/6"
50/bounce
50/bounce
Stratification lines are approximate. In-situ, the transition may be gradual.
DEPTH
LOCATION: See Exhibit A-2
GRAPHIC LOG
Hammer Type: Rope and Cathead
Latitude: 40.56146° Longitude: -105.07925°
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-WELL 20175071 255 JOHNSON DRIVE.GPJ TERRACON_DATATEMPLATE.GDT 9/8/17
SWELL- CONSOL
/LOAD
(%/psf)
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
PERCENT FINES
WATER LEVEL
OBSERVATIONS
SAMPLE TYPE
DEPTH (Ft.)
5
10
15
20
25
0.3
0.4
8.0
12.0
29.2
ASPHALT, 3 inches
AGGREGATE BASE COURSE, 2 inches
SANDY LEAN CLAY, brown, soft to
medium stiff
CLAYEY SAND, brown, dense to very
dense
SEDIMENTARY BEDROCK -
SANDSTONE, brown, hard to very hard
Boring Terminated at 29.2 Feet
19
17
21
20
30-18-12 47
Top cap
Cement seal
above
bentonite seal
Bentonite chips
with riser pipe
Solid pipe in
sand
Screen pack in
sand
4-4-2
N=6
2-3
25 - 50/5"
50/2"
50/2"
50/2"
Stratification lines are approximate. In-situ, the transition may be gradual.
DEPTH
LOCATION: See Exhibit A-2
GRAPHIC LOG
Hammer Type: Rope and Cathead
Latitude: 40.5613° Longitude: -105.07882°
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-WELL 20175071 255 JOHNSON DRIVE.GPJ TERRACON_DATATEMPLATE.GDT 9/11/17
SWELL- CONSOL
/LOAD
(%/psf)
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
PERCENT FINES
WATER LEVEL
OBSERVATIONS
SAMPLE TYPE
DEPTH (Ft.)
5
10
APPENDIX B
LABORATORY TESTING
Geotechnical Engineering Report
255 Johnson Drive ■ Fort Collins, Colorado
September 8, 2017 ■ Terracon Project No. 20175071
Responsive ■ Resourceful ■ Reliable Exhibit B-1
Laboratory Testing Description
The soil and bedrock samples retrieved during the field exploration were returned to the laboratory
for observation by the project geotechnical engineer. At that time, the field descriptions were
reviewed and an applicable laboratory testing program was formulated to determine engineering
properties of the subsurface materials.
Laboratory tests were conducted on selected soil and bedrock samples. The results of these
tests are presented on the boring logs and in this appendix. The test results were used for the
geotechnical engineering analyses, and the development of foundation and earthwork
recommendations. The laboratory tests were performed in general accordance with applicable
locally accepted standards. Soil samples were classified in general accordance with the Unified
Soil Classification System described in Appendix C. 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 judgment.
Visual classification Grain-size analysis
Moisture content Consolidation/swell
Dry density Shear strength, as appropriate
Atterberg limits Water-soluble sulfates
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: 20175071
PROJECT: 255 Johnson Drive
SITE: 255 Johnson Drive
Fort Collins, CO
CLIENT: Next Chapter Properties
Champaign, IL
EXHIBIT: B-2
1901 Sharp Point Dr Ste C
Fort Collins, CO
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. ATTERBERG LIMITS 20175071 255 JOHNSON DRIVE.GPJ TERRACON_DATATEMPLATE.GDT 9/8/17
2 - 3
14 - 14.5
19 - 19.3
4 - 5
14 - 15
9 - 10.5
4 - 5.5
4 - 5
B1
B1
B1
B2
B2
B3
B4
B6
LL USCS
54
15
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: 20175071
PROJECT: 255 Johnson Drive
SITE: 255 Johnson Drive
Fort Collins, CO
CLIENT: Next Chapter Properties
Champaign, IL
EXHIBIT: B-3
1901 Sharp Point Dr Ste C
Fort Collins, CO
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GRAIN SIZE: USCS-2 20175071 255 JOHNSON DRIVE.GPJ TERRACON_DATATEMPLATE.GDT 9/8/17
0.6
0.0
2.4
3.2
25.5
9.5
2
9.5
12.5
19
0.096
0.183
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: 20175071
PROJECT: 255 Johnson Drive
SITE: 255 Johnson Drive
Fort Collins, CO
CLIENT: Next Chapter Properties
Champaign, IL
EXHIBIT: B-4
1901 Sharp Point Dr Ste C
Fort Collins, CO
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GRAIN SIZE: USCS-2 20175071 255 JOHNSON DRIVE.GPJ TERRACON_DATATEMPLATE.GDT 9/8/17
0.2
5.9
3.4
9.5
19
9.5
0.166
0.154
26
30
30
B3
-4
-2
0
2
4
6
8
10
100 1,000 10,000
AXIAL STRAIN, %
PRESSURE, psf
SWELL CONSOLIDATION TEST
ASTM D4546
NOTES: Sample exhibited slight compression when inundated at an applied pressure of 1000 psf.
PROJECT: 255 Johnson Drive PROJECT NUMBER: 20175071
SITE: 255 Johnson Drive
Fort Collins, CO
CLIENT: Next Chapter Properties
Champaign, IL
EXHIBIT: B-5
1901 Sharp Point Dr Ste C
Fort Collins, CO
Specimen Identification Classification , pcf
102 21
WC, %
B2 4 - 5 ft SANDY LEAN CLAY
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. 65155045-SWELL/CONSOL 20175071 255 JOHNSON DRIVE.GPJ TERRACON_DATATEMPLATE.GDT 9/8/17
-4
-2
0
2
4
6
8
10
100 1,000 10,000
AXIAL STRAIN, %
PRESSURE, psf
SWELL CONSOLIDATION TEST
ASTM D4546
NOTES: Sample exhibited compression of 0.3 percent when inundated at an applied pressure of 150 psf.
PROJECT: 255 Johnson Drive PROJECT NUMBER: 20175071
SITE: 255 Johnson Drive
Fort Collins, CO
CLIENT: Next Chapter Properties
Champaign, IL
EXHIBIT: B-6
1901 Sharp Point Dr Ste C
Fort Collins, CO
Specimen Identification Classification , pcf
114 15
WC, %
B4 2 - 3 ft SILTY CLAY
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. 65155045-SWELL/CONSOL 20175071 255 JOHNSON DRIVE.GPJ TERRACON_DATATEMPLATE.GDT 9/8/17
0
50
100
150
200
250
300
350
400
450
500
550
0 1.0 2.0 3.0 4.0
LL PL PI
2.39
5.73
Percent < #200 Sieve
AXIAL STRAIN - %
Remarks:
SPECIMEN FAILURE PHOTOGRAPH
SAMPLE DESCRIPTION: SANDSTONE BEDROCK
Unconfined Compressive Strength (psf)
Undrained Shear Strength: (psf)
UNCONFINED COMPRESSION TEST
ASTM D2166
80
SAMPLE TYPE: D&M RING
Assumed Specific Gravity:
Calculated Void Ratio:
Height / Diameter Ratio:
SPECIMEN TEST DATA
2.40
0.70
Moisture Content: %
Dry Density: pcf
Diameter: in.
Height: in.
Calculated Saturation: %
Failure Strain: %
Strain Rate: in/min
COMPRESSIVE STRESS - psf
22
100
159
SAMPLE LOCATION: B1 @ 9 - 10 Inches
PROJECT NUMBER: 20175071
PROJECT: 255 Johnson Drive
SITE: 255 Johnson Drive
Fort Collins, CO
CLIENT: Next Chapter Properties
Champaign, IL
EXHIBIT: B-7
1901 Sharp Point Dr Ste C
Fort Collins, CO
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. A6161107-UNCONFINED WITH PHOTOS 20175071 255 JOHNSON DRIVE.GPJ TERRACON_DATATEMPLATE.GDT 9/8/17
0
50
100
150
200
250
300
350
400
450
500
550
0 1.0 2.0 3.0 4.0
LL PL PI
2.36
5.99
Percent < #200 Sieve
AXIAL STRAIN - %
Remarks:
SPECIMEN FAILURE PHOTOGRAPH
SAMPLE DESCRIPTION: SANDSTONE BEDROCK
Unconfined Compressive Strength (psf)
Undrained Shear Strength: (psf)
UNCONFINED COMPRESSION TEST
ASTM D2166
258
SAMPLE TYPE: D&M RING
Assumed Specific Gravity:
Calculated Void Ratio:
Height / Diameter Ratio:
SPECIMEN TEST DATA
2.54
2.34
Moisture Content: %
Dry Density: pcf
Diameter: in.
Height: in.
Calculated Saturation: %
Failure Strain: %
Strain Rate: in/min
COMPRESSIVE STRESS - psf
22
101
515
SAMPLE LOCATION: B4 @ 9 - 10 Inches
PROJECT NUMBER: 20175071
PROJECT: 255 Johnson Drive
SITE: 255 Johnson Drive
Fort Collins, CO
CLIENT: Next Chapter Properties
Champaign, IL
EXHIBIT: B-8
1901 Sharp Point Dr Ste C
Fort Collins, CO
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. A6161107-UNCONFINED WITH PHOTOS 20175071 255 JOHNSON DRIVE.GPJ TERRACON_DATATEMPLATE.GDT 9/8/17
APPENDIX C
SUPPORTING DOCUMENTS
Exhibit: C-1
Unconfined
Compressive
Strength
Qu, (tsf)
0.25 to 0.50
1.00 to 2.00
> 4.00
less than 0.25
0.50 to 1.00
2.00 to 4.00
Non-plastic
Low
Medium
High
DESCRIPTION OF SYMBOLS AND ABBREVIATIONS
Hand Penetrometer
Torvane
Dynamic Cone Penetrometer
Photo-Ionization Detector
Organic Vapor Analyzer
SAMPLING
WATER LEVEL
FIELD TESTS
(HP)
(T)
(DCP)
(PID)
(OVA)
GENERAL NOTES
Over 12 in. (300 mm)
12 in. to 3 in. (300mm to 75mm)
3 in. to #4 sieve (75mm to 4.75 mm)
#4 to #200 sieve (4.75mm to 0.075mm
Passing #200 sieve (0.075mm)
Particle Size
< 5
5 - 12
> 12
Percent of
Dry Weight
Descriptive Term(s)
of other constituents
RELATIVE PROPORTIONS OF FINES
0
1 - 10
11 - 30
> 30
Plasticity Index
Soil classification is based on the Unified Soil Classification System. Coarse Grained Soils have more than 50% of their dry
weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand. Fine Grained Soils have
less than 50% of their dry weight retained on a #200 sieve; they are principally described as clays if they are plastic, and
silts if they are slightly plastic or non-plastic. Major constituents may be added as modifiers and minor constituents may be
added according to the relative proportions based on grain size. In addition to gradation, coarse-grained soils are defined
on the basis of their in-place relative density and fine-grained soils on the basis of their consistency.
LOCATION AND ELEVATION NOTES
Percent of
Dry Weight
Major Component
of Sample
UNIFIED SOIL CLASSIFICATION SYSTEM
Exhibit C-2
Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A
Soil Classification
Group
Symbol Group Name B
Coarse Grained Soils:
More than 50% retained
on No. 200 sieve
Gravels:
More than 50% of
coarse fraction retained
on No. 4 sieve
Clean Gravels:
Less than 5% fines C
Cu 4 and 1 Cc 3 E GW Well-graded gravel F
Cu 4 and/or 1 Cc 3 E GP Poorly graded gravel F
Gravels with Fines:
More than 12% fines C
Fines classify as ML or MH GM Silty gravel F,G,H
Fines classify as CL or CH GC Clayey gravel F,G,H
Sands:
50% or more of coarse
fraction passes No. 4
sieve
Clean Sands:
Less than 5% fines D
Cu 6 and 1 Cc 3 E SW Well-graded sand I
Cu 6 and/or 1 Cc 3 E SP Poorly graded sand I
Sands with Fines:
More than 12% fines D
Fines classify as ML or MH SM Silty sand G,H,I
Fines classify as CL or CH SC Clayey sand G,H,I
Fine-Grained Soils:
50% or more passes the
No. 200 sieve
Silts and Clays:
Liquid limit less than 50
Inorganic:
PI 7 and plots on or above “A” line J CL Lean clay K,L,M
PI 4 or plots below “A” line J ML Silt K,L,M
Organic:
Liquid limit - oven dried
0.75 OL
Organic clay K,L,M,N
Liquid limit - not dried Organic silt K,L,M,O
Silts and Clays:
Liquid limit 50 or more
Inorganic:
PI plots on or above “A” line CH Fat clay K,L,M
PI plots below “A” line MH Elastic Silt K,L,M
Organic:
Liquid limit - oven dried
0.75 OH
Organic clay K,L,M,P
Liquid limit - not dried Organic silt K,L,M,Q
Highly organic soils: Primarily organic matter, dark in color, and organic odor PT Peat
A Based on the material passing the 3-inch (75-mm) sieve
B If field sample contained cobbles or boulders, or both, add “with cobbles
or boulders, or both” to group name.
DESCRIPTION OF ROCK PROPERTIES
Exhibit C-3
WEATHERING
Fresh Rock fresh, crystals bright, few joints may show slight staining. Rock rings under hammer if crystalline.
Very slight Rock generally fresh, joints stained, some joints may show thin clay coatings, crystals in broken face show
bright. Rock rings under hammer if crystalline.
Slight Rock generally fresh, joints stained, and discoloration extends into rock up to 1 in. Joints may contain clay. In
granitoid rocks some occasional feldspar crystals are dull and discolored. Crystalline rocks ring under hammer.
Moderate Significant portions of rock show discoloration and weathering effects. In granitoid rocks, most feldspars are dull
and discolored; some show clayey. Rock has dull sound under hammer and shows significant loss of strength
as compared with fresh rock.
Moderately severe All rock except quartz discolored or stained. In granitoid rocks, all feldspars dull and discolored and majority
show kaolinization. Rock shows severe loss of strength and can be excavated with geologist’s pick.
Severe All rock except quartz discolored or stained. Rock “fabric” clear and evident, but reduced in strength to strong
soil. In granitoid rocks, all feldspars kaolinized to some extent. Some fragments of strong rock usually left.
Very severe All rock except quartz discolored or stained. Rock “fabric” discernible, but mass effectively reduced to “soil” with
only fragments of strong rock remaining.
Complete Rock reduced to ”soil”. Rock “fabric” not discernible or discernible only in small, scattered locations. Quartz may
be present as dikes or stringers.
HARDNESS (for engineering description of rock – not to be confused with Moh’s scale for minerals)
Very hard Cannot be scratched with knife or sharp pick. Breaking of hand specimens requires several hard blows of
geologist’s pick.
Hard Can be scratched with knife or pick only with difficulty. Hard blow of hammer required to detach hand specimen.
Moderately hard Can be scratched with knife or pick. Gouges or grooves to ¼ in. deep can be excavated by hard blow of point of
a geologist’s pick. Hand specimens can be detached by moderate blow.
Medium Can be grooved or gouged 1/16 in. deep by firm pressure on knife or pick point. Can be excavated in small
chips to pieces about 1-in. maximum size by hard blows of the point of a geologist’s pick.
Soft Can be gouged or grooved readily with knife or pick point. Can be excavated in chips to pieces several inches in
size by moderate blows of a pick point. Small thin pieces can be broken by finger pressure.
Very soft Can be carved with knife. Can be excavated readily with point of pick. Pieces 1-in. or more in thickness can be
broken with finger pressure. Can be scratched readily by fingernail.
Joint, Bedding, and Foliation Spacing in Rock
a
Spacing Joints Bedding/Foliation
Less than 2 in. Very close Very thin
2 in. – 1 ft. Close Thin
1 ft. – 3 ft. Moderately close Medium
3 ft. – 10 ft. Wide Thick
More than 10 ft. Very wide Very thick
a. Spacing refers to the distance normal to the planes, of the described feature, which are parallel to each other or nearly so.
Rock Quality Designator (RQD) a Joint Openness Descriptors
RQD, as a percentage Diagnostic description Openness Descriptor
Exceeding 90 Excellent No Visible Separation Tight
90 – 75 Good Less than 1/32 in. Slightly Open
75 – 50 Fair 1/32 to 1/8 in. Moderately Open
50 – 25 Poor 1/8 to 3/8 in. Open
Less than 25 Very poor 3/8 in. to 0.1 ft. Moderately Wide
a. RQD (given as a percentage) = length of core in pieces Greater than 0.1 ft. Wide
4 in. and longer/length of run.
References: American Society of Civil Engineers. Manuals and Reports on Engineering Practice - No. 56. Subsurface Investigation for
Design and Construction of Foundations of Buildings. New York: American Society of Civil Engineers, 1976. U.S.
Department of the Interior, Bureau of Reclamation, Engineering Geology Field Manual.
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.
Trace
With
Modifier
RELATIVE PROPORTIONS OF SAND AND GRAVEL GRAIN SIZE TERMINOLOGY
Trace
With
Modifier
DESCRIPTIVE SOIL CLASSIFICATION
Boulders
Cobbles
Gravel
Sand
Silt or Clay
Descriptive Term(s)
of other constituents
< 15
15 - 29
> 30
Term
PLASTICITY DESCRIPTION
Water levels indicated on the soil boring
logs are the levels measured in the
borehole at the times indicated.
Groundwater level variations will occur
over time. In low permeability soils,
accurate determination of groundwater
levels is not possible with short term water
level observations.
Water Level After
a Specified Period of Time
Water Level After a
Specified Period of Time
Water Initially
Encountered
Modified
Dames &
Moore Ring
Sampler
Standard
Penetration
Test
Unless otherwise noted, Latitude and Longitude are approximately determined using a hand-held GPS device. The accuracy
of such devices is variable. Surface elevation data annotated with +/- indicates that no actual topographical survey was
conducted to confirm the surface elevation. Instead, the surface elevation was approximately determined from topographic
maps of the area.
STRENGTH TERMS
BEDROCK
Loose
Medium Dense
Dense
0 - 3
4 - 9
10 - 29
30 - 50
7 - 18
19 - 58
Very Soft
Soft
Medium-Stiff
Stiff
Very Stiff
Standard
Penetration or
N-Value
Blows/Ft.
2 - 4
4 - 8
8 - 15
< 3
5 - 9
19 - 42
> 42
30 - 49
50 - 89
20 - 29
Medium Hard
Very Dense
RELATIVE DENSITY OF COARSE-GRAINED
SOILS
Descriptive
Term
(Density)
Very Loose
> 50
Ring
Sampler
Blows/Ft.
0 - 6
59 - 98
> 99
Descriptive
Term
(Consistency)
Hard
0 - 1
Ring
Sampler
Blows/Ft.
3 - 4
10 - 18
Ring
Sampler
Blows/Ft.
< 30
90 - 119
Standard
Penetration or
N-Value
Blows/Ft.
Descriptive
Term
(Consistency)
Weathered
Firm
Very Hard
CONSISTENCY OF FINE-GRAINED SOILS
(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
Standard
Penetration or
N-Value
Blows/Ft.
_ 15 - 30
> 30
> 119
< 20
30 - 49
50 - 79
>79
Hard
B4
B6
LL PL PI
finefine
SILT OR CLAY
%Gravel %Sand
COBBLES GRAVEL SAND
coarse medium
%Clay
67.1
44.1
46.6
%Silt %Fines
SANDY LEAN CLAY (CL)
CLAYEY SAND (SC)
CLAYEY SAND (SC)
USCS Classification
19
WC (%)
9 - 10.5
4 - 5.5
4 - 5
Boring ID Depth
Boring ID Depth
D60
32.6
50.1
50.0
9 - 10.5
4 - 5.5
4 - 5
D30 D10
Cc Cu
D100
8
14
12
18
16
18
coarse
B3
B4
B6
0.182
8.368
0.113
0.09
1.184
29
NP
NP
43
NP
B1
B1
B1
B2
B2
LL PL PI
finefine
SILT OR CLAY
%Gravel %Sand
COBBLES GRAVEL SAND
coarse medium
%Clay
54.0
15.2
24.4
74.0
5.8
%Silt %Fines
SANDY SILT (ML)
SILTY SAND (SM)
SILTY SAND (SM)
SANDY LEAN CLAY (ML)
POORLY GRADED GRAVEL with SILT and SAND (GP-GM)
USCS Classification
18
WC (%)
2 - 3
14 - 14.5
19 - 19.3
4 - 5
14 - 15
Boring ID Depth
Boring ID Depth
D60
45.4
84.8
73.2
22.7
45.4
2 - 3
14 - 14.5
19 - 19.3
4 - 5
14 - 15
D30 D10
Cc Cu
D100
0.94
29
NP
NP
43
NP
NP
NP
NP
NP
NP
coarse
46.96
B1
B1
B1
B2
B2 0.178
24
74
6
67
44
47
29
NP
NP
43
NP
8
14
12
NP
NP
NP
NP
NP
18
16
18
29
NP
NP
43
NP
26
30
30
Fines
ML
SM
SM
ML
GP-GM
CL
SC
SC
SANDY SILT
SILTY SAND
SILTY SAND
SANDY LEAN CLAY
POORLY GRADED GRAVEL with SILT and SAND
SANDY LEAN CLAY
CLAYEY SAND
CLAYEY SAND
Boring ID Depth PL PI Description
CL-ML
15
20
25
INSTALLATION
DETAILS
FIELD TEST
RESULTS
255 Johnson Drive
Fort Collins, CO
SITE:
Page 1 of 1
Advancement Method:
4-inch solid-stem
Abandonment Method:
Boring completed as 2-inch diameter well.
Notes:
Project No.: 20175071
Drill Rig: CME 55
Boring Started: 08-31-2017
BORING LOG NO. B6
CLIENT:Properties Next Chapter
Champaign, IL
Driller: Dakota Drilling, Inc.
Boring Completed: 08-31-2017
Exhibit: A-6
See Exhibit A-3 for description of field procedures.
See Appendix B for description of laboratory
procedures and additional data (if any).
See Appendix C for explanation of symbols and
abbreviations.
PROJECT: 255 Johnson Drive
1901 Sharp Point Dr Ste C
Fort Collins, CO
11 feet while drilling
WATER LEVEL OBSERVATIONS
INSTALLATION
DETAILS
FIELD TEST
RESULTS
255 Johnson Drive
Fort Collins, CO
SITE:
Page 1 of 1
Advancement Method:
4-inch solid-stem
Abandonment Method:
Boring completed as 2-inch diameter well.
Notes:
Project No.: 20175071
Drill Rig: CME 55
Boring Started: 08-31-2017
BORING LOG NO. B5
CLIENT:Properties Next Chapter
Champaign, IL
Driller: Dakota Drilling, Inc.
Boring Completed: 08-31-2017
Exhibit: A-8
See Exhibit A-3 for description of field procedures.
See Appendix B for description of laboratory
procedures and additional data (if any).
See Appendix C for explanation of symbols and
abbreviations.
PROJECT: 255 Johnson Drive
1901 Sharp Point Dr Ste C
Fort Collins, CO
4 feet while drilling
WATER LEVEL OBSERVATIONS
LL-PL-PI
PERCENT FINES
WATER LEVEL
OBSERVATIONS
SAMPLE TYPE
DEPTH (Ft.)
5
10
15
20
25
INSTALLATION
DETAILS
FIELD TEST
RESULTS
255 Johnson Drive
Fort Collins, CO
SITE:
Page 1 of 1
Advancement Method:
4-inch solid-stem
Abandonment Method:
Boring completed as 2-inch diameter well.
Notes:
Project No.: 20175071
Drill Rig: CME 55
Boring Started: 09-01-2017
BORING LOG NO. B4
CLIENT:Properties Next Chapter
Champaign, IL
Driller: Dakota Drilling, Inc.
Boring Completed: 09-01-2017
Exhibit: A-7
See Exhibit A-3 for description of field procedures.
See Appendix B for description of laboratory
procedures and additional data (if any).
See Appendix C for explanation of symbols and
abbreviations.
PROJECT: 255 Johnson Drive
1901 Sharp Point Dr Ste C
Fort Collins, CO
8 feet while drilling
WATER LEVEL OBSERVATIONS
10
15
20
25
INSTALLATION
DETAILS
FIELD TEST
RESULTS
255 Johnson Drive
Fort Collins, CO
SITE:
Page 1 of 1
Advancement Method:
4-inch solid-stem
Abandonment Method:
Boring completed as 2-inch diameter well.
Notes:
Project No.: 20175071
Drill Rig: CME 55
Boring Started: 09-01-2017
BORING LOG NO. B3
CLIENT:Properties Next Chapter
Champaign, IL
Driller: Dakota Drilling, Inc.
Boring Completed: 09-01-2017
Exhibit: A-6
See Exhibit A-3 for description of field procedures.
See Appendix B for description of laboratory
procedures and additional data (if any).
See Appendix C for explanation of symbols and
abbreviations.
PROJECT: 255 Johnson Drive
1901 Sharp Point Dr Ste C
Fort Collins, CO
6 feet while drilling
WATER LEVEL OBSERVATIONS
ATTERBERG
LIMITS
LL-PL-PI
PERCENT FINES
WATER LEVEL
OBSERVATIONS
SAMPLE TYPE
DEPTH (Ft.)
5
10
15
20
25
INSTALLATION
DETAILS
FIELD TEST
RESULTS
255 Johnson Drive
Fort Collins, CO
SITE:
Page 1 of 1
Advancement Method:
4-inch solid-stem
Abandonment Method:
Boring completed as 2-inch diameter well.
Notes:
Project No.: 20175071
Drill Rig: CME 55
Boring Started: 08-31-2017
BORING LOG NO. B2
CLIENT:Properties Next Chapter
Champaign, IL
Driller: Dakota Drilling, Inc.
Boring Completed: 08-31-2017
Exhibit: A-5
See Exhibit A-3 for description of field procedures.
See Appendix B for description of laboratory
procedures and additional data (if any).
See Appendix C for explanation of symbols and
abbreviations.
PROJECT: 255 Johnson Drive
1901 Sharp Point Dr Ste C
Fort Collins, CO
8 feet while drilling
WATER LEVEL OBSERVATIONS
PERCENT FINES
WATER LEVEL
OBSERVATIONS
SAMPLE TYPE
DEPTH (Ft.)
5
10
15
20
25
INSTALLATION
DETAILS
FIELD TEST
RESULTS
255 Johnson Drive
Fort Collins, CO
SITE:
Page 1 of 1
Advancement Method:
4-inch solid-stem
Abandonment Method:
Boring completed as 2-inch diameter well.
Notes:
Project No.: 20175071
Drill Rig: CME 55
Boring Started: 08-31-2017
BORING LOG NO. B1
CLIENT:Properties Next Chapter
Champaign, IL
Driller: Dakota Drilling, Inc.
Boring Completed: 08-31-2017
Exhibit: A-4
See Exhibit A-3 for description of field procedures.
See Appendix B for description of laboratory
procedures and additional data (if any).
See Appendix C for explanation of symbols and
abbreviations.
PROJECT: 255 Johnson Drive
1901 Sharp Point Dr Ste C
Fort Collins, CO
8 feet while drilling
WATER LEVEL OBSERVATIONS