HomeMy WebLinkAboutAFFORDABLE SELF STORAGE - PDP - PDP170005 - SUBMITTAL DOCUMENTS - ROUND 3 - GEOTECHNICAL (SOILS) REPORTGeotechnical Engineering Report
BETCO Self-Storage
Northeast of Conifer Street and Red Cedar Circle
Fort Collins, Colorado
August 25, 2016
Terracon Project No. 20165074
Prepared for:
Hauser Architects PC
Loveland, Colorado
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 Corrosion Protection (Water-Soluble Sulfates) .....................................................3
3.4 Groundwater ........................................................................................................3
4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION ......................................4
4.1 Geotechnical Considerations ...............................................................................4
4.1.1 Potentially Unstable Clay Subgrade Soils .................................................4
4.1.2 Shallow Groundwater ...............................................................................4
4.1.3 Expansive Soils ........................................................................................4
4.1.4 Foundation Recommendations .................................................................5
4.2 Earthwork.............................................................................................................5
4.2.1 Site Preparation ........................................................................................5
4.2.2 Demolition ................................................................................................5
4.2.3 Excavation ................................................................................................6
4.2.4 Subgrade Preparation ...............................................................................7
4.2.5 Fill Materials and Placement ......................................................................7
4.2.6 Compaction Requirements ........................................................................8
4.2.7 Utility Trench Backfill ................................................................................8
4.2.8 Grading and Drainage ...............................................................................9
4.3 Foundations .......................................................................................................10
4.3.1 Spread Footings - Design Recommendations .........................................10
4.3.2 Spread Footings - Construction Considerations ......................................11
4.3.3 Drilled Piers Bottomed in Bedrock - Design Recommendations ..............11
4.3.4 Drilled Piers Bottomed in Bedrock - Construction Considerations ...........12
4.4 Seismic Considerations......................................................................................13
4.5 Floor Systems ....................................................................................................13
4.6 Elevator Pit ........................................................................................................13
4.6.1 Elevator Pit Design Recommendations ...................................................14
4.6.2 Elevator Pit Design Recommendations ...................................................14
4.7 Lateral Earth Pressures .....................................................................................15
4.8 Pavements .........................................................................................................16
4.8.1 Pavements – Subgrade Preparation .......................................................16
4.8.2 Pavements – Design Recommendations ................................................17
4.8.3 Pavements – Construction Considerations .............................................19
4.8.4 Pavements – Maintenance .....................................................................19
5.0 GENERAL COMMENTS ...............................................................................................20
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-10 Boring Logs
Appendix B – LABORATORY TESTING
Exhibit B-1 Laboratory Testing Description
Exhibit B-2 Atterberg Limits Test Results
Exhibit B-3 Grain-size Distribution Test Results
Exhibits B-4 and B-5 Swell-consolidation Test Results
Exhibits B-6 and B-7 Unconfined Compression Test Results
Exhibit B-8 Water-soluble Sulfate 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
Exhibit C-4 Laboratory Test Significance and Purpose
Exhibits C-5 and C-6 Report Terminology
Geotechnical Engineering Report
BETCO Self-Storage ■ Fort Collins, Colorado
August 25, 2016 ■ Terracon Project No. 20165074
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EXECUTIVE SUMMARY
A geotechnical investigation has been performed for the proposed BETCO Self-Storage Facility to
be constructed northeast of Conifer Street and Red Cedar Circle in Fort Collins, Colorado. Seven
(7) borings, presented as Exhibits A-4 through A-10 and designated as Boring No. 1 through Boring
No. 7, were performed to depths of approximately 15.5 to 34.4 feet below existing site grades. This
report specifically addresses the recommendations for the proposed BETCO Self-Storage
structures, foundations, associated driving and parking areas and earthwork. Detailed
recommendations for the design of storm water retention features and the pond are outside our
scope of work. 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:
In general, subsurface condition consisted of approximately 4½ to 9 feet of lean clay with
varying amounts of silt and sand over about 12½ to 16½ feet of poorly graded sand with
gravel. Sandstone bedrock was encountered below the poorly graded sand and extended
to maximum depths explored of about 35 feet.
We recommend the proposed self-storage buildings be constructed on shallow spread
footing foundation systems provided the soils below the proposed footings are over-
excavated to a depth of 2 feet and replaced with moisture conditioned, properly compacted
engineered fill. On-site soils are suitable for reuse as over-excavation backfill below
proposed buildings.
As an alternative, the proposed buildings may be constructed on a drilled pier foundation
system bottomed in bedrock
A slab-on-grade floor system is recommended for the proposed buildings provided the soils
below the floor are over-excavated to a depth of 12 inches and replaced with moisture
conditioned, properly compacted engineered fill. On-site soils are suitable for reuse as over-
excavation backfill below proposed buildings.
The minimum pavement section for the proposed parking area is 4 inches of asphalt
underlain by 4 inches of aggregate base course. The minimum pavement section for the
drive lanes is 4½ inches of asphalt underlain by 6 inches of aggregate base course. Rigid
pavement recommendations are included in the 4.8.2 Pavements – Design
Recommendations section of this report.
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
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discussed in the 4.2.8 Grading and Drainage section of this report be followed to reduce
potential movement.
The 2012 International Building Code, Table 1613.5.2 IBC seismic site classification for this
site is D.
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
BETCO Self-Storage
Northeast of Conifer Street and Red Cedar Circle
Fort Collins, Colorado
Terracon Project No. 20165074
August 25, 2016
1.0 INTRODUCTION
This report presents the results of our geotechnical engineering services performed for the
proposed BETCO Self-Storage Facility to be located northeast of the intersection of Conifer Street
and Red Cedar Circle 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 floor slab design and construction
grading and drainage pavement construction
lateral earth pressures earthwork
seismic considerations
Our geotechnical engineering scope of work for this project included the initial site visit, the
advancement of seven (7) test borings to depths ranging from approximately 15.5 to 34.4 feet
below existing site grades, laboratory testing for soil engineering properties and engineering
analyses to provide foundation, floor system and 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 proposed construction includes one two-story climate controlled
self-storage facility as well as multiple single-story, self-storage
buildings. Paved access drives and parking areas are also planned.
A detention pond is planned on the east side of the storage units.
Geotechnical Engineering Report
BETCO Self-Storage ■ Fort Collins, Colorado
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Item Description
Below-grade areas
No below-grade areas are planned; however, an elevator pit may be
used in the two-story climate controlled building.
Traffic loading
NAPA Traffic Class (assumed):
Automobile Parking Areas: Class I
Truck traffic and main drives: Class II
2.2 Site Location and Description
Item Description
Location
The project site is located northeast of the intersection of Conifer
Street and Red Cedar Circle in Fort Collins, Colorado.
Existing site features
The north side of the site is currently occupied by a fenced area filled
with cars and what appears to be old equipment. The south side of
the site is currently undeveloped land.
Surrounding developments
The site is bordered by Conifer Street to the south and Red Cedar
Circle to the west. To the north and east of the site are industrial
development lots.
Current ground cover
The ground in the fenced area is a gravel surface with some native
weeds. The ground on the south side of the site is covered with
native grasses and weeds.
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
Lean clay with varying amounts of
silt and sand
About 4½ to 9 feet below
existing site grades.
Very soft to very stiff
Poorly graded sand with gravel
About 19½ to 22 feet below
existing site grades.
Medium dense to very dense
Sandstone bedrock
To the maximum depth of
exploration of about 34 feet.
Very hard
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BETCO Self-Storage ■ Fort Collins, Colorado
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3.2 Laboratory Testing
Representative soil samples were selected for swell-consolidation testing and exhibited no
movement to 3½ percent swell when wetted. The sandstone is considered to have low expansive
potential or non-expansive. Two samples of lean clay soils exhibited unconfined compressive
strengths of approximately 416 and 4,319 pounds per square foot (psf). Samples of site soils
selected for plasticity testing exhibited low to moderate plasticity with liquid limits ranging from
non-plastic to 38 and plasticity indices ranging from non-plastic to 21. Laboratory test results are
presented in Appendix B.
3.3 Corrosion Protection (Water-Soluble Sulfates)
Results of water-soluble sulfate testing indicate that ASTM Type V, or modified Type II portland
cement should be specified for all project concrete on and below grade. As an alternative, ACI
allows the use of cement that conforms to ASTM C150 Type II requirements, if it meets the Type
V performance requirements (ASTM C452) of ASTM C150 Table 4. ACI 201 also allows a blend
of any type of portland cement and fly ash with an expansion of less than 0.05 percent at 6 months
when tested in accordance with ASTM C1012. Foundation concrete should be designed for
severe sulfate exposure in accordance with the provisions of the ACI Design Manual, Section
318, Chapter 4.
3.4 Groundwater
The boreholes were observed while drilling and after completion for the presence and level of
groundwater. In addition, temporary piezometers made of slotted PVC pipe was installed in two of
the borings and delayed water levels were also obtained in those 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.
Elevation of
groundwater 11 days
after drilling, ft.
1 7 Backfilled after drilling Backfilled after drilling
2 10 Backfilled after drilling Backfilled after drilling
3 9 Backfilled after drilling Backfilled after drilling
4 9 Backfilled after drilling Backfilled after drilling
5 8 Backfilled after drilling Backfilled after drilling
6 9.5 6 93.4
7 9 7.8 90.4
These observations represent groundwater conditions at the time of the field exploration and
approximately 11 days later, 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,
Geotechnical Engineering Report
BETCO Self-Storage ■ Fort Collins, Colorado
August 25, 2016 ■ Terracon Project No. 20165074
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and other factors.
Groundwater level fluctuations occur due to seasonal variations, amount of rainfall, runoff and
other factors not evident at the time the borings were performed. Therefore, groundwater levels
during construction or at other times in the life of the structures 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.
Fluctuations in groundwater levels can best be determined by implementation of a groundwater
monitoring plan. Such a plan would include installation of groundwater piezometers, and periodic
measurement of groundwater levels over a longer period of time.
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 structures,
pavements, and other site improvements.
4.1.1 Potentially Unstable Clay Subgrade Soils
Based on the soils encountered in our borings, portions of the upper lean clay soils may be at
moisture contents that could result in unstable conditions below foundations, exterior concrete
flatwork, and pavement. These conditions will likely require corrective work prior to completion of
the planned over-excavation below the buildings. Exposure to significant precipitation events,
snowmelt or repeated rubber tire traffic could also develop unstable conditions. It is likely that
some subgrade areas below the site will require stabilization.
4.1.2 Shallow Groundwater
As previously stated, groundwater was measured at depths ranging from about 7 to 10 feet below
existing site grades during drilling operations. Terracon recommends maintaining a separation of
at least 3 feet between the bottom of proposed below-grade foundations and measured
groundwater levels. It is also possible and likely that groundwater levels below this site may rise
due to rainfall and seasonal variations.
4.1.3 Expansive Soils
Laboratory testing indicates the native clay soils exhibited non-expansive to moderate expansive
potential at the samples in-situ moisture content. However, it is our opinion the sample that had
a higher swell potential also had a much lower moisture content and all on-site materials will
exhibit a higher expansive potential if the lean clays undergo a significant loss of moisture.
Geotechnical Engineering Report
BETCO Self-Storage ■ Fort Collins, Colorado
August 25, 2016 ■ Terracon Project No. 20165074
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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
We recommend the proposed self-storage buildings be constructed on shallow spread footing
foundation systems provided the soils below the proposed footings are over-excavated to a depth of
2 feet and replaced with moisture conditioned, properly compacted engineered fill. On-site soils are
suitable for reuse as over-excavation backfill below proposed buildings. As an alternative, the
proposed buildings may be constructed on a drilled pier foundation system bottomed in bedrock.
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,
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 and any other deleterious materials
from the proposed construction areas. 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.
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.
4.2.2 Demolition
Demolition of the existing fence and associated concrete entrance 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
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BETCO Self-Storage ■ Fort Collins, Colorado
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materials derived from the demolition of existing structures and pavements should be removed from
the site. The types of foundation systems supporting the existing fence are not known.
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.
4.2.3 Excavation
It is anticipated that excavations for the proposed construction can be accomplished with
conventional earthmoving equipment. Excavations into the on-site soils will encounter weak and/or
saturated soil conditions with possible caving conditions.
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 septic tanks, vaults, basements, and
utilities was not observed during the site reconnaissance, such features could be encountered
during construction. If unexpected fills or underground facilities are encountered, such features
should be removed and the excavation thoroughly cleaned prior to backfill placement and/or
construction.
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.
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.
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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
Due to the variations of density in the upper lean clays, we recommend the top 2 feet of soils
below footing foundations and the top 12 inches of soil below floor slabs be over-excavated,
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. In addition,
the top 8 inches of the ground surface at the base of the over-excavation and below other
improvement planned on the site should be scarified, moisture conditioned, and recompacted to
at least 95 percent of the maximum dry unit weight as determined by ASTM D698.
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. Use of geotextiles could also be considered as a
stabilization technique. 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. 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 pavement subgrade. It should be
noted that lean clay soils may require reworking to adjust the moisture content to meet the
compaction criteria.
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 15-60
Soil Properties Values
Liquid Limit 35 (max.)
Plastic Limit 6 (max.)
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Soil Properties Values
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.
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)
-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 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 structures should be designed with flexible
couplings, so minor deviations in alignment do not result in breakage or distress. Utility knockouts
in foundation walls should be oversized to accommodate 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.
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BETCO Self-Storage ■ Fort Collins, Colorado
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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 and pavement areas.
4.2.8 Grading and Drainage
All grades must be adjusted to provide effective drainage away from the proposed buildings 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 10 feet
beyond the perimeter of the proposed buildings, 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 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 (if any) located adjacent to structures 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 not be used 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 or to a detention pond or other appropriate
outfall.
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BETCO Self-Storage ■ Fort Collins, Colorado
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4.3 Foundations
We recommend the proposed self-storage buildings be constructed on shallow spread footing
foundation systems provided the soils below the proposed footings are over-excavated to a depth of
2 feet and replaced with moisture conditioned, properly compacted engineered fill. On-site soils are
suitable for reuse as over-excavation backfill below proposed buildings. As an alternative, the
proposed buildings may be constructed on a drilled pier foundation system bottomed in bedrock.
4.3.1 Spread Footings - Design Recommendations
Description Values
Bearing material
Properly prepared on-site soil or new, properly
placed engineered fill.
Maximum allowable bearing pressure 1 2,500 psf
Lateral earth pressure coefficients 2
Active, Ka = 0.31
Passive, Kp = 3.3
At-rest, Ko = 0.47
Sliding coefficient 2 µ = 0.5
Moist soil unit weight ɣ = 110 pcf
Minimum embedment depth below finished
grade 3
30 inches
Estimated total movement About 1 inch
1. The recommended maximum allowable bearing pressure assumes any unsuitable fill or soft soils, if
encountered, will be over-excavated and either recompacted to 95% the maximum dry unit weight
as determined by ASTM D698 or 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.
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 4.2.8 Grading and Drainage section of this report will nullify the movement
estimates provided above.
Geotechnical Engineering Report
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August 25, 2016 ■ Terracon Project No. 20165074
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4.3.2 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 proposed buildings 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 4.2 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 subgrade conditions are anticipated as excavations approach the groundwater surface.
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.
4.3.3 Drilled Piers Bottomed in Bedrock - Design Recommendations
As an alternative to a spread footing foundation system, the proposed buildings may be constructed
on a drilled pier foundation system bottomed in bedrock.
Description Value
Minimum pier length 18 feet
Minimum pier diameter 18 inches
Minimum bedrock embedment 1 6 feet
Maximum allowable end-bearing pressure 35,000 psf
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.
Geotechnical Engineering Report
BETCO Self-Storage ■ Fort Collins, Colorado
August 25, 2016 ■ Terracon Project No. 20165074
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Site grading details were not fully understood at the time we prepared this report. If significant
fills are planned in the proposed building areas, longer drilled pier lengths may be required. 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
Sand and
Gravel
Sandstone
Bedrock
LPILE soil type Soft clay
Sand
(submerged)
Stiff clay
Effective unit weight (pcf) above groundwater 120 - 120
Effective unit weight (pcf) below groundwater 62
Average undrained shear strength (psf) 500 N/A 9,000
Average angle of internal friction, (degrees) N/A 35 N/A
Coefficient of subgrade reaction, k (pci)*
100 - static
30 - cyclic
60
2,000- static
800 – cyclic
Strain, 50 (%) 0.010 N/A 0.004
1. For purposes of LPILE analysis, assume a groundwater depth of about 7 feet below existing
ground surface.
4.3.4 Drilled Piers Bottomed in Bedrock - Construction Considerations
Drilling to design depth should be possible with conventional single-flight power augers on the
majority of the site; however, specialized drilling equipment may be required for very hard bedrock
layers.
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.
Geotechnical Engineering Report
BETCO Self-Storage ■ Fort Collins, Colorado
August 25, 2016 ■ Terracon Project No. 20165074
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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 bedrock 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
2012 International Building Code (IBC) 1 D 2
1. In general accordance with the 2012 International Building Code, Table 1613.5.2.
2. The 2012 International Building Code (IBC) 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 25½ 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.
4.5 Floor Systems
A slab-on-grade may be utilized for the interior floor system for the proposed structures provided the
soils below the floor are over-excavated to a depth of 12 inches and replaced with moisture
conditioned, properly compacted engineered fill. On-site soils are suitable for reuse as over-
excavation backfill below proposed buildings. Even when bearing on properly prepared soils,
movement of the slab-on-grade floor 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. Careful consideration should
be taken to the 4.2 Earthwork section of this report to prevent unwanted movement of the floor
slab. If the estimated movement cannot be tolerated, a structurally-supported floor system,
supported independent of the subgrade materials, is recommended.
4.6 Elevator Pit
We assume an elevator pit will be included in the interior of the two-story climate-controlled
building. The elevator pit will likely consist of reinforced concrete walls with a concrete base slab.
Based on our experience with this type of structure, we anticipate the base slabs will be about 5
feet below the level of the finished floor slab.
Geotechnical Engineering Report
BETCO Self-Storage ■ Fort Collins, Colorado
August 25, 2016 ■ Terracon Project No. 20165074
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4.6.1 Elevator Pit Design Recommendations
Subsurface conditions in the elevator pit excavations are anticipated to consist of native clays and
sands and gravels. Groundwater was encountered at depths of about 7 feet below existing site
grades at the time of our field exploration. However, groundwater levels can and should be
expected to fluctuate over time.
Depending upon final site grades and elevator pit elevations, groundwater could impact the
performance of the pit base slab. If the pit slab is constructed at our within about 4 feet of the
level of groundwater, the pit slab should be designed and constructed to resist hydrostatic
pressures and uplift due to the effects of buoyancy or it should be protected by an underdrain
system for permanent dewatering. “Water-proofing” of the pit will also be needed if permanent
dewatering is not used. Terracon should evaluate the groundwater level within each elevator pit
area prior to or during construction.
The elevator pit walls should be designed for lateral earth pressures imposed by the soil backfill.
Earth pressure will primarily be influenced by structural design of the walls, conditions of wall
restraint and type, compaction and drainage of backfill. For purposes of design, we have
assumed approximately 5 feet of fill will be retained by the pit walls and backfill will consist of the
on-site lean clays. 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.
Active earth pressure is commonly used for design of walls (such as free-standing cantilever
retaining walls) and assumes some wall rotation and deflection. For walls that can deflect and
rotate around the base, the top lateral movements of about ¼ to ½ percent or more of the wall
height, lower “active pressures could be considered for design. Use of the “active” condition
assumes deflection and thus cracking of walls could occur. For rigid walls where negligible or
very little rotation and deflection will occur, “at-rest” lateral earth pressures should be used in the
design.
Reinforced concrete pit walls should be designed for lateral earth pressures and/or combined
hydrostatic and lateral earth pressures at least equal to those indicated in the table in the 4.7
Lateral Earth Pressures section of this report.
The lateral earth pressures presented above do not include a factory of safety. As such,
appropriate factors of safety should be applied to these values. Furthermore, the lateral earth
pressures do not include the influence of surcharge, equipment of floor loading, which should be
added.
4.6.2 Elevator Pit Design Recommendations
Depending on groundwater conditions at the time of construction and the final depth of the pits,
some method of temporary dewatering may be needed during construction. Dewatering should
continue through the excavation, foundation construction and backfilling operations to ensure
proper construction.
Geotechnical Engineering Report
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The elevator pit excavations should be observed by the geotechnical engineer to confirm that the
subsurface conditions are consistent with those encountered in our test borings. If the soil
conditions encountered differ from those presented in this report, supplemental recommendations
will be required. Where expansive clays, low strength soils or otherwise unsuitable bearing
materials are encountered in the excavation, these materials should be over-excavated to the
minimum depth determined by the geotechnical engineer and replaced with approved engineered
fill. Terracon should be contacted to evaluate bearing conditions in the elevator pit excavations
well in advance of forming foundations.
4.7 Lateral Earth Pressures
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
Geotechnical Engineering Report
BETCO Self-Storage ■ Fort Collins, Colorado
August 25, 2016 ■ Terracon Project No. 20165074
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Earth Pressure
Conditions
Coefficient for Backfill
Type
Equivalent Fluid
Density (pcf)
Surcharge
Pressure,
p1 (psf)
Earth
Pressure,
p2 (psf)
Active (Ka)
Sands and Gravels - 0.22
Lean Clay - 0.33
26
40
(0.22)S
(0.33)S
(26)H
(40)H
At-Rest (Ko)
Sands and Gravels - 0.36
Lean Clay - 0.50
43
60
(0.36)S
(0.50)S
(43)H
(60)H
Passive (Kp)
Sands and Gravels – 4.6
Lean Clay – 3.0
552
360
---
---
---
---
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 120 pcf;
Horizontal backfill, compacted between 95 and 98 percent of maximum dry unit weight as
determined by ASTM D698;
Loading from heavy compaction equipment not included;
No hydrostatic pressures acting on wall;
No dynamic loading;
No safety factor included in soil parameters; and
Ignore passive pressure in frost zone.
To control hydrostatic pressure behind the wall we recommend that a drain be installed at the
foundation wall with a collection pipe leading to a reliable discharge. If this is not possible, then
combined hydrostatic and lateral earth pressures should be calculated for lean clay backfill using
an equivalent fluid weighing 90 and 100 pcf for active and at-rest conditions, respectively. For
Geotechnical Engineering Report
BETCO Self-Storage ■ Fort Collins, Colorado
August 25, 2016 ■ Terracon Project No. 20165074
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grading and paving. All pavement areas should be moisture conditioned and properly compacted
to the recommendations in this report immediately prior to paving.
4.8.2 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 – 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 Course1
Portland
Cement
Concrete
Total
Automobile Parking Areas A 4 4 -- 8
Geotechnical Engineering Report
BETCO Self-Storage ■ Fort Collins, Colorado
August 25, 2016 ■ Terracon Project No. 20165074
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Traffic Area
Alternative
Recommended Pavement Thicknesses (Inches)
Asphaltic
Concrete
Surface
Aggregate
Base Course1
Portland
Cement
Concrete
Total
(NAPA Class I and ACI Category A) B - - 5 5
Main Traffic Corridors
(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:
Properties Value
Compressive strength 4,000 psi
Cement type1 Type V portland cement
Entrained air content (%) 5 to 8
Concrete aggregate ASTM C33 and CDOT section 703
1. If concrete is placed on aggregate base course Type I or II portland cement may be used as it will
not be in contact with the soil.
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.
Geotechnical Engineering Report
BETCO Self-Storage ■ Fort Collins, Colorado
August 25, 2016 ■ Terracon Project No. 20165074
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Although not required for structural support, a minimum 4-inch thick aggregate base course layer
is recommended for the PCC pavements to help reduce the potential for slab curl, shrinkage
cracking, and subgrade “pumping” through joints. Proper joint spacing will also be required for
PCC pavements to prevent excessive slab curling and shrinkage cracking. All joints should be
sealed to prevent entry of foreign material and dowelled where necessary for load transfer.
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.
4.8.3 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.
4.8.4 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
Geotechnical Engineering Report
BETCO Self-Storage ■ Fort Collins, Colorado
August 25, 2016 ■ Terracon Project No. 20165074
Responsive ■ Resourceful ■ Reliable 20
priority when implementing a planned pavement maintenance program and provides the highest
return on investment for pavements.
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
TOPOGRAPHIC MAP IMAGE COURTESY OF
THE U.S. GEOLOGICAL SURVEY
QUADRANGLES INCLUDE: FORT COLLINS,
CO (1984).
SITE LOCATION MAP
BETCO Self-Storage
Northeast of Conifer Street and Red Cedar Circle
Fort Collins, CO
1901 Sharp Point Dr Ste C
Fort Collins, CO 80525-4429
20165074
DIAGRAM IS FOR GENERAL LOCATION ONLY,
AND IS NOT INTENDED FOR CONSTRUCTION
PURPOSES
Project Manager:
Drawn by:
Checked by:
Approved by:
MGH
EDB
EDB
EDB
8/22/2016
Project No.
File Name:
Date:
A-1
Exhibit
SITE
Scale: 1”=2,000’
LEGEND
APPROXIMATE BORING
LOCATION
APPROXIMATE
TEMPORARY BENCHMARK (top
nut of yellow fire hydrant)
EXPLORATION PLAN
1901 Sharp Point Dr Ste C
Fort Collins, CO 80525-4429
20165074
AERIAL PHOTOGRAPHY PROVIDED BY
MICROSOFT BING MAPS
BETCO Self-Storage
Northeast of Conifer Street and Red Cedar Circle
Fort Collins, CO
DIAGRAM IS FOR GENERAL LOCATION ONLY,
AND IS NOT INTENDED FOR CONSTRUCTION
PURPOSES
Project Manager:
Drawn by:
Checked by:
Approved by:
MGH
EDB
EDB
EDB
8/22/2016
Scale:
Project No.
File Name:
Date:
AS SHOWN
A-2
Exhibit
Geotechnical Engineering Report
BETCO Self-Storage ■ Fort Collins, Colorado
August 25, 2016 ■ Terracon Project No. 20165074
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 ground
surface elevation was surveyed at each boring location referencing the temporary benchmark
shown on Exhibit A-2 using an engineer’s level.
The borings were drilled with a CME-75 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. Disturbed bulk samples were
obtained from auger cuttings. 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 automatic SPT hammer was used to advance the samplers in the borings performed on this
site. A greater efficiency is typically achieved with the automatic hammer compared to the
conventional safety hammer operated with a cathead and rope. Published correlations between the
SPT values and soil properties are based on the lower efficiency cathead and rope method. This
higher efficiency affects the standard penetration resistance blow count value by increasing the
penetration per hammer blow over what would be obtained using the cathead and rope method. The
effect of the automatic hammer's efficiency has been considered in the interpretation and analysis of
the subsurface information for this report.
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 and
several days after drilling. After subsequent groundwater measurements were obtained, the
borings were backfilled with auger cuttings and sand (if needed) and patched (if needed). Some
settlement of the backfill and/or patch may occur and should be repaired as soon as possible.
16
26
7
10
23
27
19
97 27-20-7
97.5
91
78
64
3-2-2
N=4
2-2
5-9-12
N=21
19-50/6"
N=69/12"
30-50/5"
N=80/11"
N=50/1"
N=50/1"
N=50/0"
0.5
7.0
20.0
34.0
6-INCH VEGETATIVE LAYER
SILTY CLAY WITH SAND (CL-ML), with gravel, light brown,
soft to medium stiff
POORLY GRADED SAND WITH GRAVEL, with cobbles,
coarse to medium grained, reddish-brown, medium dense to
dense
SEDIMENTARY BEDROCK - SANDSTONE,
yellowish-brown to gray, very hard
Boring Terminated at 34 Feet
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
GRAPHIC LOG
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20165074.GPJ TERRACON2015.GDT 8/25/16
Northeast of Conifer Street and Red Cedar Circle
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
4-inch solid-stem auger
Abandonment Method:
Boring backfilled with soil cuttings upon completion.
1901 Sharp Point Dr Ste C
Fort Collins, CO
Notes:
Project No.: 20165074
Drill Rig: CME-75
Boring Started: 8/10/2016
BORING LOG NO. 1
CLIENT: Hauser Architects PC
Loveland, Colorado
Driller: Drilling Engineers, Inc.
Boring Completed: 8/10/2016
Exhibit: A-4
11
13
2
8
22
21
18
21
108
100
93.5
81
66.5
20-27 +3.5/150
6-6-4
N=10
12-13-13
N=26
10-16-14
N=30
12-37-45
N=82
N=50/4"
N=50/3"
N=50/1"
0.5
7.0
19.5
34.1
6-INCH VEGETATIVE LAYER
SILTY CLAY WITH SAND, with gravel, light brown, stiff
POORLY GRADED SAND WITH GRAVEL, with silt and
cobbles, coarse to medium grained, reddish-brown, medium
dense to dense
SEDIMENTARY BEDROCK - SANDSTONE,
yellowish-brown, very hard
Boring Terminated at 34.1 Feet
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
GRAPHIC LOG
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20165074.GPJ TERRACON2015.GDT 8/25/16
Northeast of Conifer Street and Red Cedar Circle
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
4-inch solid-stem auger
Abandonment Method:
Boring backfilled with soil cuttings upon completion.
1901 Sharp Point Dr Ste C
Fort Collins, CO
Notes:
Project No.: 20165074
Drill Rig: CME-75
Boring Started: 8/11/2016
BORING LOG NO. 2
CLIENT: Hauser Architects PC
Loveland, Colorado
Driller: Drilling Engineers, Inc.
Boring Completed: 8/11/2016
Exhibit: A-5
416
14
20
4
11
19
18
16
16
115
107 25-18-7
92
78
66
8-9
3-4
9-16-16
N=32
17-21-28
N=49
20-37-50/3"
N=87/9"
N=50/1"
N=50/2"
N=50/1"
8.0
22.0
34.1
SANDY SILTY CLAY, with gravel, brown to reddish-brown,
medium stiff to stiff
POORLY GRADED SAND WITH GRAVEL, with cobbles,
coarse to medium grained, reddish-brown, dense to very dense
SEDIMENTARY BEDROCK - SANDSTONE,
yellowish-brown to gray, very hard
Boring Terminated at 34.1 Feet
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
GRAPHIC LOG
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20165074.GPJ TERRACON2015.GDT 8/25/16
Northeast of Conifer Street and Red Cedar Circle
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
6-inch hollow-stem auger
Abandonment Method:
Boring backfilled with soil cuttings upon completion.
1901 Sharp Point Dr Ste C
Fort Collins, CO
Notes:
Project No.: 20165074
Drill Rig: CME-75
Boring Started: 8/11/2016
BORING LOG NO. 3
CLIENT: Hauser Architects PC
Loveland, Colorado
Driller: Drilling Engineers, Inc.
Boring Completed: 8/11/2016
Exhibit: A-6
See Exhibit A-3 for description of field procedures.
See Appendix B for description of laboratory
12
2
21
13
24
18
20
NP
95
78.5
69.5
68.5
65.5
7-9-11
N=20
7-6
9-10-12
N=22
36-50/5"
N=86/11'
27-50/3"
N=77/9"
N=50/3"
N=50/3"
N=50/2"
4.5
21.0
30.0
31.0
34.2
SANDY SILTY CLAY, with gravel, brown to reddish-brown,
stiff to very stiff
POORLY GRADED SAND WITH GRAVEL (SP), with
cobbles, coarse to medium grained, reddish-brown, medium
dense to dense
SEDIMENTARY BEDROCK - SANDSTONE,
yellowish-brown to gray, very hard
2 foot layer of cemented bedrock at 30 feet below existing site
grades
Boring Terminated at 34.2 Feet
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
GRAPHIC LOG
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20165074.GPJ TERRACON2015.GDT 8/25/16
Northeast of Conifer Street and Red Cedar Circle
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
6-inch hollow-stem auger
Abandonment Method:
Boring backfilled with soil cuttings upon completion.
1901 Sharp Point Dr Ste C
Fort Collins, CO
Notes:
Project No.: 20165074
Drill Rig: CME-75
Boring Started: 8/11/2016
BORING LOG NO. 4
CLIENT: Hauser Architects PC
Loveland, Colorado
20
21
8
18
22
24
21
20
99
96
89.5
76.5
62
0.0/500
4-3-2
N=5
0-1
6-12-15
N=27
11-33-50
N=83
N=50/5"
N=50/3"
N=50/3"
N=50/4"
0.5
7.0
20.0
34.4
6-INCH VEGETATIVE LAYER
SILTY CLAY WITH SAND, with gravel, light brown, very soft
to medium stiff
POORLY GRADED SAND WITH GRAVEL, with cobbles,
fine to coarse grained, reddish-brown, medium dense to dense
SEDIMENTARY BEDROCK - SANDSTONE,
yellowish-brown to gray, very hard
Boring Terminated at 34.4 Feet
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
GRAPHIC LOG
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20165074.GPJ TERRACON2015.GDT 8/25/16
Northeast of Conifer Street and Red Cedar Circle
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
6-inch hollow-stem auger
Abandonment Method:
Boring backfilled with soil cuttings upon completion.
1901 Sharp Point Dr Ste C
Fort Collins, CO
Notes:
Project No.: 20165074
Drill Rig: CME-75
Boring Started: 8/11/2016
BORING LOG NO. 5
CLIENT: Hauser Architects PC
Loveland, Colorado
Driller: Drilling Engineers, Inc.
Boring Completed: 8/11/2016
Exhibit: A-8
13
20
11
9
113
38-17-21
99
90.5
84
10-12
4-4-4
N=8
8-13-9
N=22
6-17-18
N=35
0.5
9.0
15.5
6-INCH VEGETATIVE LAYER
LEAN CLAY (CL), with gravel, light brown to brown, stiff to
very stiff
POORLY GRADED SAND WITH GRAVEL, with cobbles,
coarse to medium grained, reddish-brown to brown, medium
dense to dense
Boring Terminated at 15.5 Feet
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
GRAPHIC LOG
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20165074.GPJ TERRACON2015.GDT 8/25/16
Northeast of Conifer Street and Red Cedar Circle
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
4-inch solid-stem auger
Abandonment Method:
Temporary piezometer installed.
1901 Sharp Point Dr Ste C
Fort Collins, CO
Notes:
Project No.: 20165074
Drill Rig: CME-75
Boring Started: 8/11/2016
BORING LOG NO. 6
CLIENT: Hauser Architects PC
Loveland, Colorado
Driller: Drilling Engineers, Inc.
Boring Completed: 8/11/2016
Exhibit: A-9
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: BETCO Self-Storage
UNCONFINED
COMPRESSIVE
STRENGTH (psf)
WATER
CONTENT (%)
4319
9
14
17
18
110 31-17-14
97.5
89
82.5
3-4-5
N=9
3-5
6-9-12
N=21
13-13-15
N=28
0.5
9.0
15.5
6-INCH VEGETATIVE LAYER
LEAN CLAY (CL), with gravel, light brown to brown, medium
stiff to stiff
POORLY GRADED SAND WITH GRAVEL, with cobbles,
coarse to medium grained, reddish-brown to brown, medium
dense
Boring Terminated at 15.5 Feet
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
GRAPHIC LOG
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20165074.GPJ TERRACON2015.GDT 8/25/16
Northeast of Conifer Street and Red Cedar Circle
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
4-inch solid-stem auger
Abandonment Method:
Temporary piezometer installed.
1901 Sharp Point Dr Ste C
Fort Collins, CO
Notes:
Project No.: 20165074
Drill Rig: CME-75
Boring Started: 8/11/2016
BORING LOG NO. 7
CLIENT: Hauser Architects PC
Loveland, Colorado
Driller: Drilling Engineers, Inc.
Boring Completed: 8/11/2016
Exhibit: A-10
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: BETCO Self-Storage
UNCONFINED
COMPRESSIVE
STRENGTH (psf)
WATER
CONTENT (%)
APPENDIX B
LABORATORY TESTING
Geotechnical Engineering Report
BETCO Self-Storage ■ Fort Collins, Colorado
August 25, 2016 ■ Terracon Project No. 20165074
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. Rock samples were visually classified in
general accordance with the description of rock properties presented 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.
Water content Plasticity index
Grain-size distribution
Consolidation/swell
Unconfined Compressive strength
Dry density
Water-soluble sulfate content
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
Boring ID Depth PL PI Description
SILTY CLAY with SAND
SANDY SILTY CLAY
POORLY GRADED SAND with GRAVEL
LEAN CLAY
LEAN CLAY
CL-ML
CL-ML
SP
CL
CL
Fines
P
L
A
S
T
I
C
I
T
Y
I
N
D
E
X
LIQUID LIMIT
"U" Line
"A" Line
27
25
NP
38
31
20
18
NP
17
17
7
7
NP
21
14
71
59
3
87
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
1
3
4
6
7
27
25
NP
38
31
0.79
0.08
2.318
2
19
19
2
12.5
6
16
20
30
40
50
1.5
6 200
8
10
0.0
2.2
17.0
0.0
0.9
0.289
14
71.2
59.0
2.7
-4
-2
0
2
4
6
8
10
100 1,000 10,000
AXIAL STRAIN, %
PRESSURE, psf
SWELL CONSOLIDATION TEST
ASTM D4546
NOTES: The sample exhibited 3.5 percent swell upon wetting under an applied pressure of 150 psf.
Specimen Identification Classification , pcf
2 108 11
WC, %
2 - 3 ft
PROJECT NUMBER: 20165074
PROJECT: BETCO Self-Storage
SITE: Northeast of Conifer Street and Red Cedar
Circle
Fort Collins, Colorado
CLIENT: Hauser Architects PC
Loveland, Colorado
EXHIBIT: B-4
1901 Sharp Point Dr Ste C
Fort Collins, CO
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. TC_CONSOL_STRAIN-USCS 20165074.GPJ TERRACON2012.GDT 8/24/16
-4
-2
0
2
4
6
8
10
100 1,000 10,000
AXIAL STRAIN, %
PRESSURE, psf
SWELL CONSOLIDATION TEST
ASTM D4546
NOTES: The sample exhibited no movement upon wetting under an applied pressure of 500 psf.
Specimen Identification Classification , pcf
5 99 21
WC, %
4 - 5 ft
PROJECT NUMBER: 20165074
PROJECT: BETCO Self-Storage
SITE: Northeast of Conifer Street and Red Cedar
Circle
Fort Collins, Colorado
CLIENT: Hauser Architects PC
Loveland, Colorado
EXHIBIT: B-5
1901 Sharp Point Dr Ste C
Fort Collins, CO
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. TC_CONSOL_STRAIN-USCS 20165074.GPJ TERRACON2012.GDT 8/24/16
0
500
1,000
1,500
2,000
2,500
3,000
3,500
4,000
4,500
0 2 4 6 8 10
LL PL PI
2.41
3.99
Percent < #200 Sieve
59
AXIAL STRAIN - %
Remarks:
SPECIMEN FAILURE PHOTOGRAPH
SAMPLE DESCRIPTION: SANDY SILTY CLAY(CL-ML)
25 18 7
Unconfined Compressive Strength (psf)
Undrained Shear Strength: (psf)
UNCONFINED COMPRESSION TEST
ASTM D2166
208
SAMPLE TYPE: D&M RING
Assumed Specific Gravity:
Calculated Void Ratio:
Height / Diameter Ratio:
SPECIMEN TEST DATA
1.66
6.02
Moisture Content: %
Dry Density: pcf
Diameter: in.
Height: in.
Calculated Saturation: %
Failure Strain: %
Strain Rate: in/min
COMPRESSIVE STRESS - psf
20
107
416
SAMPLE LOCATION: 3 @ 4 - 5 feet
PROJECT NUMBER: 20165074
PROJECT: BETCO Self-Storage
SITE: Northeast of Conifer Street and Red Cedar
Circle
Fort Collins, Colorado
CLIENT: Hauser Architects PC
Loveland, Colorado
EXHIBIT: B-6
1901 Sharp Point Dr Ste C
Fort Collins, CO
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. UNCONFINED WITH PHOTOS 20165074.GPJ TERRACON2012.GDT 8/24/16
0
500
1,000
1,500
2,000
2,500
3,000
3,500
4,000
4,500
0 2 4 6 8 10
LL PL PI
2.41
4.87
Percent < #200 Sieve
85
AXIAL STRAIN - %
Remarks:
SPECIMEN FAILURE PHOTOGRAPH
SAMPLE DESCRIPTION: LEAN CLAY(CL)
31 17 14
Unconfined Compressive Strength (psf)
Undrained Shear Strength: (psf)
UNCONFINED COMPRESSION TEST
ASTM D2166
2159
SAMPLE TYPE: D&M RING
Assumed Specific Gravity:
Calculated Void Ratio:
Height / Diameter Ratio:
SPECIMEN TEST DATA
2.02
3.70
Moisture Content: %
Dry Density: pcf
Diameter: in.
Height: in.
Calculated Saturation: %
Failure Strain: %
Strain Rate: in/min
COMPRESSIVE STRESS - psf
14
109
4319
SAMPLE LOCATION: 7 @ 4 - 5 feet
PROJECT NUMBER: 20165074
PROJECT: BETCO Self-Storage
SITE: Northeast of Conifer Street and Red Cedar
Circle
Fort Collins, Colorado
CLIENT: Hauser Architects PC
Loveland, Colorado
EXHIBIT: B-7
1901 Sharp Point Dr Ste C
Fort Collins, CO
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. UNCONFINED WITH PHOTOS 20165074.GPJ TERRACON2012.GDT 8/24/16
TASK NO: 160818014
Analytical Results
Terracon, Inc. - Fort Collins
Eric D. Bernhardt
Company:
Report To:
Company:
Bill To:
1901 Sharp Point Drive
Suite C
Fort Collins CO 80525
Accounts Payable
Terracon, Inc. - A/P
18001 W. 106th St
Suite 300
Olathe KS 66061
20165074
Date Reported: 8/25/16
Task No.: 160818014
Matrix: Soil - Geotech
Date Received: 8/18/16
Client Project:
Client PO:
CustomerFt Sample ID 20165074 - BH#1 @ 4-5
Test Method
Lab Number: 160818014-01
Result
Sulfate - Water Soluble 0.572 % AASHTO T290-91/ ASTM D4327
CustomerFt Sample ID 20165074 - BH#4 @ 2-3.5
Test Method
Lab Number: 160818014-02
Result
Sulfate - Water Soluble 0.032 % AASHTO T290-91/ ASTM D4327
240 South Main Street / Brighton, CO 80601-0507 / 303-659-2313
Mailing Address: P.O. Box 507 / Brighton, CO 80601-0507 / Fax: 303-659-2315
DATA APPROVED FOR RELEASE BY
Abbreviations/ References:
160818014
AASHTO - American Association of State Highway and Transportation Officials.
ASTM - American Society for Testing and Materials.
ASA - American Society of Agronomy.
DIPRA - Ductile Iron Pipe Research Association Handbook of Ductile Iron Pipe.
APPENDIX C
SUPPORTING DOCUMENTS
Exhibit: C-1
Unconfined Compressive Strength
Qu, (psf)
500 to 1,000
2,000 to 4,000
4,000 to 8,000
1,000 to 2,000
less than 500
> 8,000
Non-plastic
Low
Medium
High
DESCRIPTION OF SYMBOLS AND ABBREVIATIONS
SAMPLING
WATER LEVEL
FIELD TESTS
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
Trace
With
Modifier
RELATIVE PROPORTIONS OF SAND AND GRAVEL GRAIN SIZE TERMINOLOGY
Trace
With
Modifier
DESCRIPTIVE SOIL CLASSIFICATION
Boulders
Cobbles
Gravel
Sand
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
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.
Exhibit C-4
LABORATORY TEST
SIGNIFICANCE AND PURPOSE
Test Significance Purpose
California Bearing
Ratio
Used to evaluate the potential strength of subgrade soil,
subbase, and base course material, including recycled
materials for use in road and airfield pavements.
Pavement Thickness
Design
Consolidation
Used to develop an estimate of both the rate and amount of
both differential and total settlement of a structure.
Foundation Design
Direct Shear
Used to determine the consolidated drained shear strength
of soil or rock.
Bearing Capacity,
Foundation Design,
and Slope Stability
Dry Density
Used to determine the in-place density of natural, inorganic,
fine-grained soils.
Index Property Soil
Behavior
Expansion
Used to measure the expansive potential of fine-grained soil
and to provide a basis for swell potential classification.
Foundation and Slab
Design
Gradation
Used for the quantitative determination of the distribution of
particle sizes in soil.
Soil Classification
Liquid & Plastic Limit,
Plasticity Index
Used as an integral part of engineering classification
systems to characterize the fine-grained fraction of soils, and
to specify the fine-grained fraction of construction materials.
Soil Classification
Permeability
Used to determine the capacity of soil or rock to conduct a
liquid or gas.
Groundwater Flow
Analysis
pH Used to determine the degree of acidity or alkalinity of a soil. Corrosion Potential
Resistivity
Used to indicate the relative ability of a soil medium to carry
electrical currents.
Corrosion Potential
R-Value
Used to evaluate the potential strength of subgrade soil,
subbase, and base course material, including recycled
materials for use in road and airfield pavements.
Pavement Thickness
Design
Soluble Sulfate
Used to determine the quantitative amount of soluble
sulfates within a soil mass.
Exhibit C-5
REPORT TERMINOLOGY
(Based on ASTM D653)
Allowable Soil
Bearing Capacity
The recommended maximum contact stress developed at the interface of the foundation
element and the supporting material.
Alluvium
Soil, the constituents of which have been transported in suspension by flowing water and
subsequently deposited by sedimentation.
Aggregate Base
Course
A layer of specified material placed on a subgrade or subbase usually beneath slabs or
pavements.
Backfill A specified material placed and compacted in a confined area.
Bedrock
A natural aggregate of mineral grains connected by strong and permanent cohesive forces.
Usually requires drilling, wedging, blasting or other methods of extraordinary force for
excavation.
Bench A horizontal surface in a sloped deposit.
Caisson (Drilled
Pier or Shaft)
A concrete foundation element cast in a circular excavation which may have an enlarged base.
Sometimes referred to as a cast-in-place pier or drilled shaft.
Coefficient of
Friction
A constant proportionality factor relating normal stress and the corresponding shear stress at
which sliding starts between the two surfaces.
Colluvium
Soil, the constituents of which have been deposited chiefly by gravity such as at the foot of a
slope or cliff.
Compaction The densification of a soil by means of mechanical manipulation
Concrete Slab-on-
Grade
A concrete surface layer cast directly upon a base, subbase or subgrade, and typically used
as a floor system.
Differential
Movement
Unequal settlement or heave between, or within foundation elements of structure.
Earth Pressure The pressure exerted by soil on any boundary such as a foundation wall.
ESAL
Equivalent Single Axle Load, a criteria used to convert traffic to a uniform standard, (18,000
pound axle loads).
Engineered Fill
Specified material placed and compacted to specified density and/or moisture conditions
under observations of a representative of a geotechnical engineer.
Equivalent Fluid
A hypothetical fluid having a unit weight such that it will produce a pressure against a lateral
support presumed to be equivalent to that produced by the actual soil. This simplified
approach is valid only when deformation conditions are such that the pressure increases
linearly with depth and the wall friction is neglected.
Existing Fill (or
Man-Made Fill)
Materials deposited throughout the action of man prior to exploration of the site.
Existing Grade The ground surface at the time of field exploration.
Exhibit C-6
REPORT TERMINOLOGY
(Based on ASTM D653)
Expansive Potential The potential of a soil to expand (increase in volume) due to absorption of moisture.
Finished Grade The final grade created as a part of the project.
Footing A portion of the foundation of a structure that transmits loads directly to the soil.
Foundation The lower part of a structure that transmits the loads to the soil or bedrock.
Frost Depth The depth at which the ground becomes frozen during the winter season.
Grade Beam
A foundation element or wall, typically constructed of reinforced concrete, used to span between
other foundation elements such as drilled piers.
Groundwater Subsurface water found in the zone of saturation of soils or within fractures in bedrock.
Heave Upward movement.
Lithologic The characteristics which describe the composition and texture of soil and rock by observation.
Native Grade The naturally occurring ground surface.
Native Soil Naturally occurring on-site soil, sometimes referred to as natural soil.
Optimum Moisture
Content
The water content at which a soil can be compacted to a maximum dry unit weight by a given
compactive effort.
Perched Water
Groundwater, usually of limited area maintained above a normal water elevation by the
presence of an intervening relatively impervious continuous stratum.
Scarify To mechanically loosen soil or break down existing soil structure.
Settlement Downward movement.
Skin Friction (Side
Shear)
The frictional resistance developed between soil and an element of the structure such as a
drilled pier.
Soil (Earth)
Sediments or other unconsolidated accumulations of solid particles produced by the physical
and chemical disintegration of rocks, and which may or may not contain organic matter.
Strain The change in length per unit of length in a given direction.
Stress The force per unit area acting within a soil mass.
Strip To remove from present location.
Subbase A layer of specified material in a pavement system between the subgrade and base course.
Subgrade The soil prepared and compacted to support a structure, slab or pavement system.
Corrosion Potential
Unconfined
Compression
To obtain the approximate compressive strength of soils that
possess sufficient cohesion to permit testing in the
unconfined state.
Bearing Capacity
Analysis for
Foundations
Water Content
Used to determine the quantitative amount of water in a soil
mass.
Index Property Soil
Behavior
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.
Silt or Clay
Descriptive Term(s)
of other constituents
N
(HP)
(T)
(DCP)
(PID)
(OVA)
< 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
Auger
Cuttings
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.
Standard Penetration Test
Resistance (Blows/Ft.)
Hand Penetrometer
Torvane
Dynamic Cone Penetrometer
Photo-Ionization Detector
Organic Vapor Analyzer
STRENGTH TERMS
Standard Penetration or
N-Value
Blows/Ft.
Descriptive Term
(Consistency)
Descriptive Term
(Density)
CONSISTENCY OF FINE-GRAINED SOILS
(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.
(More than 50% retained on No. 200 sieve.)
Density determined by Standard Penetration Resistance
RELATIVE DENSITY OF COARSE-GRAINED SOILS
Hard > 30
> 50 Very Stiff 15 - 30
Stiff
Medium Stiff
Very Soft 0 - 1
Medium Dense
Loose Soft
Very Dense
Dense 30 - 50 8 - 15
10 - 29 4 - 8
4 - 9 2 - 4
Very Loose 0 - 3
87.5
85.1
%Fines
LL PL PI
4
1
3/4
1/2
60
fine
1
3
4
6
7
8.03
GRAIN SIZE IN MILLIMETERS
PERCENT FINER BY WEIGHT
coarse fine
U.HYDROMETERS. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS
20
18
NP
17
17
7
7
NP
21
14
0.93
D100
Cc Cu
SILT OR CLAY
4
D30 D10 %Gravel %Sand
4 - 5
4 - 5
14 - 14.9
4 - 5.5
4 - 5
3/8
3 100
3 140
2
COBBLES
GRAVEL SAND
USCS Classification
28.5
38.8
69.5
12.4
14.0
D60
coarse medium
Boring ID Depth
Boring ID Depth
GRAIN SIZE DISTRIBUTION
4 - 5
4 - 5
14 - 14.9
4 - 5.5
4 - 5
SILTY CLAY with SAND (CL-ML)
SANDY SILTY CLAY (CL-ML)
POORLY GRADED SAND with GRAVEL (SP)
LEAN CLAY (CL)
LEAN CLAY (CL)
ASTM D422 / ASTM C136
PROJECT NUMBER: 20165074
PROJECT: BETCO Self-Storage
SITE: Northeast of Conifer Street and Red Cedar
Circle
Fort Collins, Colorado
CLIENT: Hauser Architects PC
Loveland, Colorado
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 20165074.GPJ 35159097 - ATTERBERG ISSUE.GPJ 8/24/16
85
LL USCS
1
3
4
6
7
ATTERBERG LIMITS RESULTS
ASTM D4318
4 - 5
4 - 5
14 - 14.9
4 - 5.5
4 - 5
PROJECT NUMBER: 20165074
PROJECT: BETCO Self-Storage
SITE: Northeast of Conifer Street and Red Cedar
Circle
Fort Collins, Colorado
CLIENT: Hauser Architects PC
Loveland, Colorado
EXHIBIT: B-2
1901 Sharp Point Dr Ste C
Fort Collins, CO
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. ATTERBERG LIMITS 20165074.GPJ TERRACON2015.GDT 8/24/16
CL-ML
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
Surface Elev.: 98.19 (Ft.)
ELEVATION (Ft.)
SAMPLE TYPE
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
15
SWELL - CONSOL /
LOAD (%/psf)
FIELD TEST
RESULTS
DEPTH
LOCATION
Latitude: 40.60305° Longitude: -105.073°
See Exhibit A-2
9' while drilling
7.8' on 8/22/2-16
WATER LEVEL OBSERVATIONS
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
Surface Elev.: 99.37 (Ft.)
ELEVATION (Ft.)
SAMPLE TYPE
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
15
SWELL - CONSOL /
LOAD (%/psf)
FIELD TEST
RESULTS
DEPTH
LOCATION
Latitude: 40.60328° Longitude: -105.07323°
See Exhibit A-2
9.5' while drilling
6' on 8/22/2016
WATER LEVEL OBSERVATIONS
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: BETCO Self-Storage
UNCONFINED
COMPRESSIVE
STRENGTH (psf)
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
Surface Elev.: 96.6 (Ft.)
ELEVATION (Ft.)
SAMPLE TYPE
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
15
20
25
30
SWELL - CONSOL /
LOAD (%/psf)
FIELD TEST
RESULTS
DEPTH
LOCATION
Latitude: 40.60295° Longitude: -105.07343°
See Exhibit A-2
8' while drilling
WATER LEVEL OBSERVATIONS
Driller: Drilling Engineers, Inc.
Boring Completed: 8/11/2016
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: BETCO Self-Storage
UNCONFINED
COMPRESSIVE
STRENGTH (psf)
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
Surface Elev.: 99.57 (Ft.)
ELEVATION (Ft.)
SAMPLE TYPE
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
15
20
25
30
SWELL - CONSOL /
LOAD (%/psf)
FIELD TEST
RESULTS
DEPTH
LOCATION
Latitude: 40.60378° Longitude: -105.07336°
See Exhibit A-2
9' while drilling
WATER LEVEL OBSERVATIONS
procedures and additional data (if any).
See Appendix C for explanation of symbols and
abbreviations.
PROJECT: BETCO Self-Storage
UNCONFINED
COMPRESSIVE
STRENGTH (psf)
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
Surface Elev.: 100.2 (Ft.)
ELEVATION (Ft.)
SAMPLE TYPE
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
15
20
25
30
SWELL - CONSOL /
LOAD (%/psf)
FIELD TEST
RESULTS
DEPTH
LOCATION
Latitude: 40.60346° Longitude: -105.0741°
See Exhibit A-2
9' while drilling
WATER LEVEL OBSERVATIONS
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: BETCO Self-Storage
UNCONFINED
COMPRESSIVE
STRENGTH (psf)
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
Surface Elev.: 100.48 (Ft.)
ELEVATION (Ft.)
SAMPLE TYPE
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
15
20
25
30
SWELL - CONSOL /
LOAD (%/psf)
FIELD TEST
RESULTS
DEPTH
LOCATION
Latitude: 40.60384° Longitude: -105.07436°
See Exhibit A-2
10' while drilling
WATER LEVEL OBSERVATIONS
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: BETCO Self-Storage
UNCONFINED
COMPRESSIVE
STRENGTH (psf)
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
Surface Elev.: 98.09 (Ft.)
ELEVATION (Ft.)
SAMPLE TYPE
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
15
20
25
30
SWELL - CONSOL /
LOAD (%/psf)
FIELD TEST
RESULTS
DEPTH
LOCATION
Latitude: 40.60298° Longitude: -105.07437°
See Exhibit A-2
7' while drilling
WATER LEVEL OBSERVATIONS
granular backfill, an equivalent fluid weighing 85 and 90 pcf should be used for active and at-rest,
respectively. These pressures do not include the influence of surcharge, equipment or floor
loading, which should be added. Heavy equipment should not operate within a distance closer
than the exposed height of retaining walls to prevent lateral pressures more than those provided.
4.8 Pavements
4.8.1 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