HomeMy WebLinkAboutFORT COLLINS HOTEL (DOWNTOWN HOTEL) - FDP - FDP150033 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTGeotechnical Engineering Report
Front Range Colorado Hospitality Project
354 Walnut Street
Fort Collins, Colorado
January 20, 2015
Terracon Project No. 20145072
Prepared for:
McWhinney Real Estate Services, Inc.
Loveland, Colorado
Prepared by:
Terracon Consultants, Inc.
Fort Collins, Colorado
TABLE OF CONTENTS
Page
EXECUTIVE SUMMARY ............................................................................................................ i
1.0 INTRODUCTION ............................................................................................................ 1
2.0 PROJECT INFORMATION ............................................................................................ 1
2.1 Project Description .............................................................................................. 1
2.2 Site Location and Description ............................................................................. 2
3.0 SUBSURFACE CONDITIONS ....................................................................................... 2
3.1 Typical Subsurface Profile .................................................................................. 2
3.2 Laboratory Testing .............................................................................................. 3
3.3 Groundwater ....................................................................................................... 3
4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION ..................................... 4
4.1 Geotechnical Considerations .............................................................................. 4
4.1.1 Existing, Undocumented Fill .................................................................... 4
4.1.2 Shallow Groundwater .............................................................................. 4
4.1.3 Foundation Recommendations ................................................................ 5
4.2 Earthwork ........................................................................................................... 6
4.2.1 Site Preparation........................................................................................ 6
4.2.2 Demolition ............................................................................................... 6
4.2.3 Excavation ............................................................................................... 6
4.2.4 Subgrade Preparation .............................................................................. 7
4.2.5 Fill Materials and Placement ..................................................................... 8
4.2.6 Compaction Requirements ....................................................................... 9
4.2.7 Utility Trench Backfill ..............................................................................10
4.2.8 Grading and Drainage .............................................................................10
4.2.9 Exterior Slab Design and Construction ...................................................11
4.2.10 Corrosion Protection ...............................................................................11
4.3 Foundations .......................................................................................................11
4.3.1 Drilled Piers Bottomed in Bedrock - Design Recommendations ..............12
4.3.2 Drilled Piers Bottomed in Bedrock - Construction Considerations ...........12
4.3.3 Spread Footings - Design Recommendations .........................................14
4.3.4 Spread Footings - Construction Considerations ......................................14
4.3.5 Shoring Protection ..................................................................................15
4.4 Seismic Considerations......................................................................................16
4.5 Floor Systems ....................................................................................................16
4.5.1 Floor System - Design Recommendations ..............................................16
4.5.2 Floor Systems - Construction Considerations .........................................17
4.6 Lateral Earth Pressures .....................................................................................18
4.7 Pavements .........................................................................................................19
4.7.1 Pavements – Subgrade Preparation .......................................................19
4.7.2 Pavements – Design Recommendations ................................................19
4.7.3 Pavements – Construction Considerations .............................................22
4.7.4 Pavements – Maintenance .....................................................................22
5.0 GENERAL COMMENTS ...............................................................................................22
TABLE OF CONTENTS (continued)
Appendix A – FIELD EXPLORATION
Exhibit A-1 Site Location Map
Exhibit A-2 Exploration Plan
Exhibit A-3 Field Exploration Description
Exhibits A-4 to A-9 Boring Logs
Appendix B – LABORATORY TESTING
Exhibit B-1 Laboratory Testing Description
Exhibit B-2 Atterberg Limits Test Results
Exhibit B-3 Grain-size Distribution 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
Front Range Colorado Hospitality Project ■ Fort Collins, Colorado
January 20, 2015 ■ Terracon Project No. 20145072
Responsive ■ Resourceful ■ Reliable i
EXECUTIVE SUMMARY
A geotechnical investigation has been performed for the proposed Front Range Colorado
Hospitality Project to be constructed at 354 Walnut Street in Fort Collins, Colorado. Six (6)
borings, presented as Exhibits A-4 through A-9 and designated as Boring No. 1 through Boring No.
6, were performed to depths of approximately 30 to 40 feet below existing site grades. This report
specifically addresses the recommendations for the proposed hotel and associated pavements.
Borings performed in these areas are for informational purposes and will be utilized by others.
Based on the information obtained from our subsurface exploration, the site can be developed for
the proposed project. However, the following geotechnical considerations were identified and will
need to be considered:
Existing, undocumented fill was encountered in some of the borings performed on this site
to depths ranging from about 2 to 7 feet below existing site grades. The existing fill soils
should be removed and replaced with engineered fill beneath foundations and floor slabs.
We recommend constructing the proposed building on a drilled pier foundation system
bottomed in bedrock.
As a higher risk foundation alternative, shallow foundations bearing on the native granular
soils and/or siltstone/sandstone bedrock below this site may be used. Shallow foundations
bearing partially on soil and partially on very hard bedrock at different elevations have a
higher risk for differential settlement. To reduce the risk of potential differential settlement,
the upper level shallow foundations may be extended 1 to 2 feet deeper than typically
constructed for frost protection. Extending all spread footing foundations to bedrock will
also significantly reduce the risk for differential settlement and increase the allowable
bearing pressure.
A slab-on-grade floor system is recommended for the proposed building. If the basement
floor slab will bear on the bedrock below the site, we recommend over-excavating a
minimum of 1 foot below the bottom of the floor slab and replacing with properly placed
engineered fill. On-site soils and thoroughly broken down, processed siltstone/sandstone
bedrock are suitable for use as engineered fill.
At the time this report was prepared, site grading details were not completed. We
understand a partial full-depth basement is planned for this site. Depending upon the
finished floor elevation of the basement, permanent dewatering may be required due to the
shallow groundwater encountered below this site.
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
Geotechnical Engineering Report
Front Range Colorado Hospitality Project ■ Fort Collins, Colorado
January 20, 2015 ■ Terracon Project No. 20145072
Responsive ■ Resourceful ■ Reliable ii
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 C.
Close monitoring of the construction operations discussed herein will be critical in
achieving the design subgrade support. We therefore recommend that Terracon be
retained to monitor this portion of the work.
This summary should be used in conjunction with the entire report for design purposes. It
should be recognized that details were not included or fully developed in this section, and the
report must be read in its entirety for a comprehensive understanding of the items contained
herein. The section titled GENERAL COMMENTS should be read for an understanding of the
report limitations.
Responsive ■ Resourceful ■ Reliable 1
GEOTECHNICAL ENGINEERING REPORT
Front Range Colorado Hospitality Project
354 Walnut Street
Fort Collins, Colorado
Terracon Project No. 20145072
January 20, 2015
1.0 INTRODUCTION
This report presents the results of our geotechnical engineering services performed for the
proposed Front Range Colorado Hospitality Project to be located at 354 Walnut Street in Fort
Collins, Colorado. 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 six test borings to depths ranging from approximately 30 to 40 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.
Previously, Terracon prepared a Geotechnical Engineering Report (Project No. 20065048; report
dated May 3, 2006) for the 4-story mixed-use building across the street from this site. Information
from the previous study was used in the evaluation of the current project.
2.0 PROJECT INFORMATION
2.1 Project Description
Item Description
Site layout Refer to the Exploration Plan (Exhibit A-2 in Appendix A)
Geotechnical Engineering Report
Front Range Colorado Hospitality Project ■ Fort Collins, Colorado
January 20, 2015 ■ Terracon Project No. 20145072
Responsive ■ Resourceful ■ Reliable 2
Item Description
Structures
We understand the project will include a 165 room +/- key hotel
with function and restaurant space. The 4-story building will be
approximately 115,000 square feet with a partial full-depth
basement. A portion of the building may have a fifth story.
Finished floor elevation
We anticipate the finished grades will closely match the existing
grades.
Maximum loads
Column loads: 600 kips max. (assumed)
Wall loads: 2 to 5 klf (assumed)
Floor slabs: 200 psf max. (assumed)
Grading in building area
We anticipate cuts and fills on the order of 15 feet or less will be
required for the proposed construction. Deeper cuts and fills may
be required for the installation of deep utilities.
Below-grade areas A full-depth partial basement is planned for this site.
2.2 Site Location and Description
Item Description
Location
The project site is located at 354 Walnut Street in Fort Collins,
Colorado.
Existing site features Multiple buildings and asphalt pavements occupy the site.
Surrounding developments
The site is surrounded by commercial and retail stores. Walnut
Street borders the site to the west and Chestnut street borders the
site to the east.
Current ground cover
The ground is covered with asphalt pavements, concrete sidewalks
and flatwork, landscaping, and an existing building.
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 (feet)
Consistency/Density/Hardness
Asphalt pavement About 2 to 4 inches thick. --
Geotechnical Engineering Report
Front Range Colorado Hospitality Project ■ Fort Collins, Colorado
January 20, 2015 ■ Terracon Project No. 20145072
Responsive ■ Resourceful ■ Reliable 3
Material Description
Approximate Depth to
Bottom of Stratum (feet)
Consistency/Density/Hardness
Aggregate base course About 4 to 8 inches thick. --
Fill materials consisting of lean clay,
sand, and gravel
About 2 to 7 feet below existing
site grades.
--
Sand with varying amounts of silt,
gravel, and cobbles
About 9 to 12 feet below
existing site grades.
Dense to very dense
Interbedded siltstone/sandstone
bedrock
To the maximum depth of
exploration of about 25 feet.
Hard to very hard
3.2 Laboratory Testing
Samples of site soils and bedrock selected for plasticity testing exhibited non-plastic to medium
plasticity with liquid limits ranging from non-plastic to 34 and plasticity indices ranging from 6 to
15. Laboratory test results are presented in Appendix B.
3.3 Groundwater
The boreholes were observed while drilling and after completion for the presence and level of
groundwater. In addition, delayed water levels were also obtained in some 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
several days after
drilling, ft.
Elevation of
groundwater several
days after drilling, ft.
1 9.5 14.6 4962.2
2 Not encountered Not encountered --
3 Not encountered Backfilled after drilling Backfilled after drilling
4 13 11.4 4965.1
5 Not encountered Not encountered --
6 Not encountered Backfilled after drilling Backfilled after drilling
These observations represent groundwater conditions at the time of the field exploration, and
may not be indicative of other times or at other locations. Groundwater levels can be expected
to fluctuate with varying seasonal and weather conditions, and other factors.
Groundwater level fluctuations occur due to seasonal variations in the amount of rainfall, runoff
and other factors not evident at the time the borings were performed. Therefore, groundwater
levels during construction or at other times in the life of the structure may be higher or lower
Geotechnical Engineering Report
Front Range Colorado Hospitality Project ■ Fort Collins, Colorado
January 20, 2015 ■ Terracon Project No. 20145072
Responsive ■ Resourceful ■ Reliable 4
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.
In Boring Nos. 1, 2, 4, and 5 temporary piezometers were constructed in the boreholes upon
completion. Periodic groundwater measurements may be obtained for a period of up to 1 year
before the temporary piezometers will need to either be abandoned or permitted as ground water
monitoring wells through the state of Colorado.
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
building, pavements, and other site improvements.
4.1.1 Existing, Undocumented Fill
As previously noted, existing undocumented fill was encountered to depths up to about 7 feet in
the borings drilled at the site. We do not possess any information regarding whether the fill was
placed under the observation of a geotechnical engineer. We recommend removal of the
existing fill below proposed foundations and floor slabs and replacement with properly placed
engineered fill.
Support of floor slabs and pavements on or above existing fill soils is discussed in this report.
However, even with the recommended construction testing services, there is an inherent risk for
the owner that compressible fill or unsuitable material within or buried by the fill will not be
discovered. This risk of unforeseen conditions cannot be eliminated without completely
removing the existing fill, but can be reduced by performing additional testing and evaluation.
4.1.2 Shallow Groundwater
As previously stated, groundwater was measured at depths ranging from about 11.4 to 14.6 feet
below existing site grades. We understand a partial full-depth basement is planned for this site.
Terracon recommends maintaining a separation of at least 3 feet between the bottom of
proposed below-grade elements and measured groundwater levels. It is also possible and likely
that groundwater levels below this site may rise.
To reduce the potential for surface water to impact floor slab bearing soils and enter the
basement of the building, installation of a perimeter drainage system is recommended. The
drainage system should be constructed around the exterior perimeter of the basement
Geotechnical Engineering Report
Front Range Colorado Hospitality Project ■ Fort Collins, Colorado
January 20, 2015 ■ Terracon Project No. 20145072
Responsive ■ Resourceful ■ Reliable 5
foundation, and sloped at a minimum 1/8 inch per foot to a suitable outlet, such as a sump and
pump system.
The drainage system should consist of a properly-sized perforated pipe, embedded in free-
draining gravel, placed in a trench at least 12 inches in width. Gravel should extend up to within
2 feet of the surface and the top 2 feet of backfill should consist of low permeability soil. The
system should be underlain with a polyethylene moisture barrier, sealed to the foundation walls,
and extended at least to the edge of the backfill zone. The gravel should be covered with
drainage fabric prior to placement of foundation backfill.
To further reduce the potential for groundwater to affect the floor slab subgrade, an underslab
drainage system can be used. The floor slab subgrade should be graded to drain to a sump
and pump system incorporated with the perimeter drain. The drain system should include
appropriately sized perforated drain pipe embedded in at least 8 inches of free draining gravel.
The drain pipes should be sloped to provide positive drainage to the sump.
If the proposed basement will extend into the groundwater below the site, a more significant
subsurface drainage system may be required. Once more details regarding construction are
determined by the project team, Terracon is available to assist with developing a subsurface
drainage system.
4.1.3 Foundation Recommendations
We recommend supporting the proposed building on a drilled pier foundation system bottomed
in bedrock. We recommend a slab-on-grade for the interior floor system of the proposed
building. If the basement floor slab will bear on the bedrock below the site, we recommend over-
excavating a minimum of 1 foot below the bottom of the floor slab and replacing with properly
placed engineered fill. On-site soils and thoroughly broken-down, processed siltstone/sandstone
bedrock are suitable for use as engineered fill. 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.
As a higher risk foundation alternative, a spread footing foundation system bearing on the native
granular soils and/or siltstone/sandstone below this site may be used to support the proposed
building. Spread footing foundations bearing partially on soil and partially on very hard bedrock at
different elevations have a higher risk for differential settlement. To reduce the risk of potential
differential settlement, the upper level spread footing foundations may be extended 1 to 2 feet
deeper. Extending all spread footing foundations to bedrock will also significantly reduce the risk
for differential settlement and increase the allowable bearing pressure.
Geotechnical Engineering Report
Front Range Colorado Hospitality Project ■ Fort Collins, Colorado
January 20, 2015 ■ Terracon Project No. 20145072
Responsive ■ Resourceful ■ Reliable 6
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 (if any), the existing asphalt
pavement, and any other deleterious materials from the proposed construction area.
Stripped organic materials should be wasted from the site or used to re-vegetate landscaped
areas after completion of grading operations. Prior to the placement of fills, the site should be
graded to create a relatively level surface to receive fill, and to provide for a relatively uniform
thickness of fill beneath proposed structures.
4.2.2 Demolition
Demolition of the existing buildings and site features should include complete removal of all
foundation systems, below-grade structural elements, pavements, and exterior flat work within the
proposed construction area. This should include removal of any utilities to be abandoned along
with any loose utility trench backfill or loose backfill found adjacent to existing foundations. All
materials derived from the demolition of the existing structures and pavements should be removed
from the site. The types of foundation systems supporting the existing buildings are not known. If
some or all of the existing buildings are supported by drilled piers, the existing piers should be
truncated a minimum depth of 3 feet below areas of planned new construction.
Consideration could be given to re-using the asphalt 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.
Excavations penetrating the bedrock may require the use of specialized heavy-duty equipment,
together with ripping or jack-hammering to advance the excavation and facilitate rock break-up
and removal. Consideration should be given to obtaining a unit price for difficult excavation in the
contract documents for the project.
Geotechnical Engineering Report
Front Range Colorado Hospitality Project ■ Fort Collins, Colorado
January 20, 2015 ■ Terracon Project No. 20145072
Responsive ■ Resourceful ■ Reliable 7
The soils to be excavated can vary significantly across the site as their classifications are based
solely on the materials encountered in widely-spaced exploratory test borings. The contractor
should verify that similar conditions exist throughout the proposed area of excavation. If different
subsurface conditions are encountered at the time of construction, the actual conditions should be
evaluated to determine any excavation modifications necessary to maintain safe conditions.
Although evidence of underground facilities such as septic tanks, vaults, 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 existing building foundations that are exposed during site excavations (if any) should be
examined and evaluated by Terracon to determine the need for any shoring or underpinning.
Excavations should not extend into the stress influence zone of the existing foundations without
prior evaluation by Terracon. The stress influence zone is defined as the area below a line
projected down at a 1(h) to 1(v) slope from the bottom edge of the existing foundation.
Excavations within the influence zone of existing foundations can result in loss of support, and can
create settlement or failure of the existing foundations. While the evaluation of existing
foundations and the design of a shoring system are beyond the scope of this study, we can
perform these tasks as a separate study.
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. Well points may be required for
significant groundwater flow, or where excavations penetrate groundwater to a significant depth.
The subgrade soil conditions should be evaluated during the excavation process and the stability
of the soils determined at that time by the contractors’ Competent Person. 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. If any excavation, including a utility trench, is extended to
a depth of more than 20 feet, it will be necessary to have the side slopes and/or shoring system
designed by a professional engineer.
As a safety measure, it is recommended that all vehicles and soil piles be kept a minimum lateral
distance from the crest of the slope equal to the slope height. The exposed slope face should be
protected against the elements
4.2.4 Subgrade Preparation
After the deleterious materials and existing fill have been removed from the construction area,
the top 8 inches of the exposed ground surface should be scarified, moisture conditioned, and
Geotechnical Engineering Report
Front Range Colorado Hospitality Project ■ Fort Collins, Colorado
January 20, 2015 ■ Terracon Project No. 20145072
Responsive ■ Resourceful ■ Reliable 8
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, large cobbles or boulder-sized materials may be encountered beneath spread
footing foundations, floor slabs, and pavement areas. Such conditions could create point loads
on the bottom of footings, increasing the potential for differential foundation movement. If such
conditions are encountered in the excavations, the cobbles and/or boulders should be removed
within the upper 6 inches of soil below the proposed improvements and be replaced with
engineered fill, conditioned to near optimum moisture content and compacted.
After the bottom of the excavation has been compacted, engineered fill can be placed to bring
the foundations, floor slabs, and pavement subgrade to the desired grade. Engineered fill
should be placed in accordance with the recommendations presented in subsequent sections of
this report.
The stability of the subgrade may be affected by precipitation, repetitive construction traffic or
other factors. If unstable conditions develop, workability may be improved by scarifying and
drying. Alternatively, over-excavation of wet zones and replacement with granular materials
may be used, or crushed gravel and/or rock can be tracked or “crowded” into the unstable
surface soil until a stable working surface is attained. Lightweight excavation equipment may
also be used to reduce subgrade pumping.
4.2.5 Fill Materials and Placement
The on-site soils or approved granular and low plasticity cohesive imported materials may be used
as fill material. 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. On-site soils
larger than 4 inches in diameter may not be used as backfill within 6 inches of slabs on grade or
pavement subgrade. It should be noted that on-site soils will 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 15-50
Geotechnical Engineering Report
Front Range Colorado Hospitality Project ■ Fort Collins, Colorado
January 20, 2015 ■ Terracon Project No. 20145072
Responsive ■ Resourceful ■ Reliable 9
Soil Properties Value
Liquid Limit 30 (max.)
Plastic Limit 15 (max.)
Maximum Expansive Potential (%) Non-expansive1
1. Measured on a sample compacted to approximately 95 percent of the maximum dry unit weight as
determined by ASTM D698 at optimum moisture content. The sample is confined under a 100 psf
surcharge and submerged.
The recommendations for placement and compaction criteria presented assume that fill depths
will be less than 8 feet. Fills on the order of 8 feet in depth, when placed and compacted as
recommended in this report, will experience some settlement, generally 1 inch or less. The
amount and rate of settlement will be increased if water is introduced into the fill. It is noted that
settlement of the fill material due to self-weight is in addition to settlements due to structural
induced loads. It is possible to reduce the settlement due to self-weight by increasing the
compactive effort when placing the fill.
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 +2 % 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.
Geotechnical Engineering Report
Front Range Colorado Hospitality Project ■ Fort Collins, Colorado
January 20, 2015 ■ Terracon Project No. 20145072
Responsive ■ Resourceful ■ Reliable 10
4.2.7 Utility Trench Backfill
All trench excavations should be made with sufficient working space to permit construction
including backfill placement and compaction.
All underground piping within or near the proposed structure should be designed with flexible
couplings, so minor deviations in alignment do not result in breakage or distress. Utility knockouts
in foundation walls should be oversized to accommodate differential movements. It is imperative
that utility trenches be properly backfilled with relatively clean materials. If utility trenches are
backfilled with relatively clean granular material, they should be capped with at least 18 inches of
cohesive fill in non-pavement areas to reduce the infiltration and conveyance of surface water
through the trench backfill.
Utility trenches are a common source of water infiltration and migration. All utility trenches that
penetrate beneath the building should be effectively sealed to restrict water intrusion and flow
through the trenches that could migrate below the building. We recommend constructing an
effective clay “trench plug” that extends at least 5 feet out from the face of the building exterior.
The plug material should consist of clay compacted at a water content at or above the soil’s
optimum 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 building and
existing 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 structure (either during or post-
construction) can result in significantly higher soil movements than those discussed in this
report. As a result, any estimations of potential movement described in this report cannot be
relied upon if positive drainage is not obtained and maintained, and water is allowed to infiltrate
the fill and/or subgrade.
Exposed ground (if any) should be sloped at a minimum of 10 percent grade for at least 10 feet
beyond the perimeter of the proposed building, where possible. The use of swales, chases
and/or area drains may be required to facilitate drainage in unpaved areas around the perimeter
of the building. Backfill against footings and exterior walls should be properly compacted and
free of all construction debris to reduce the possibility of moisture infiltration. After construction
of the proposed building and prior to project completion, we recommend verification of final
grading be performed to document positive drainage, as described above, has been achieved.
Geotechnical Engineering Report
Front Range Colorado Hospitality Project ■ Fort Collins, Colorado
January 20, 2015 ■ Terracon Project No. 20145072
Responsive ■ Resourceful ■ Reliable 11
Flatwork and pavements will be subject to post-construction movement. Maximum grades
practical should be used for paving and flatwork to prevent areas where water can pond. In
addition, allowances in final grades should take into consideration post-construction movement
of flatwork, particularly if such movement would be critical. Where paving or flatwork abuts the
structure, care should be taken that joints are properly sealed and maintained to prevent the
infiltration of surface water.
Planters located adjacent to structure should preferably be self-contained. Sprinkler mains and
spray heads should be located a minimum of 5 feet away from the building line(s). Low-volume,
drip style landscaped irrigation should not be used near the building. Roof drains should
discharge on to pavements or be extended away from the structure a minimum of 10 feet
through the use of splash blocks or downspout extensions. A preferred alternative is to have
the roof drains discharge by solid pipe to storm sewers or to a detention pond or other
appropriate outfall.
4.2.9 Exterior Slab Design and Construction
Exterior slabs on-grade, exterior architectural features, and utilities founded on, or in backfill or
the site soils will likely experience some movement due to the volume change of the material.
Potential movement could be reduced by:
Minimizing moisture increases in the backfill;
Controlling moisture-density during placement of the backfill;
Using designs which allow vertical movement between the exterior features
and adjoining structural elements; and
Placing control joints on relatively close centers.
4.2.10 Corrosion Protection
At the time this report was prepared, the laboratory testing for water-soluble sulfates had not
been completed. We will submit a supplemental letter with the corrosive property testing results
and corrosion protection recommendations once the testing has been completed.
4.3 Foundations
We recommend constructing the proposed building on a drilled pier foundation system bottomed
in bedrock. As a higher risk foundation alternative, a spread footing foundations system bearing
on the native granular soils and/or siltstone/sandstone below this site may be used. Design
recommendations for foundations for the proposed structure and related structural elements are
presented in the following paragraphs.
Geotechnical Engineering Report
Front Range Colorado Hospitality Project ■ Fort Collins, Colorado
January 20, 2015 ■ Terracon Project No. 20145072
Responsive ■ Resourceful ■ Reliable 12
4.3.1 Drilled Piers Bottomed in Bedrock - Design Recommendations
Description Value
Estimated pier length 25 feet
Minimum pier diameter 18 inches
Minimum bedrock embedment 1 10 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.
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
Claystone
Bedrock
LPILE soil type1
Stiff clay
without free
water
Sand
(submerged)
Stiff clay
without free
water
Unit weight (pcf) 120 125 130
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 11 feet below existing ground surface
(approximate Elev. 4965 feet).
4.3.2 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 to
Geotechnical Engineering Report
Front Range Colorado Hospitality Project ■ Fort Collins, Colorado
January 20, 2015 ■ Terracon Project No. 20145072
Responsive ■ Resourceful ■ Reliable 13
cemented bedrock layers. In addition, caving soils and groundwater indicate that temporary
steel casing may be required to properly drill the piers prior to concrete placement.
Groundwater should be removed from each pier hole prior to concrete placement. Pier concrete
should be placed immediately after completion of drilling and cleaning. If pier concrete cannot
be placed in dry conditions, a tremie should be used for concrete placement. Free-fall concrete
placement in piers will only be acceptable if provisions are taken to avoid striking the concrete
on the sides of the hole or reinforcing steel. The use of a bottom-dump hopper, or an elephant's
trunk discharging near the bottom of the hole where concrete segregation will be minimized, is
recommended. Due to potential sloughing and raveling, foundation concrete quantities may
exceed calculated geometric volumes.
Casing should be withdrawn in a slow continuous manner maintaining a sufficient head of
concrete to prevent infiltration of water or caving soils or the creation of voids in pier concrete.
Pier concrete should have a relatively high fluidity when placed in cased pier holes or through a
tremie. Pier concrete with slump in the range of 5 to 7 inches is recommended.
We recommend the sides of each pier should be mechanically roughened in the claystone
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.
Geotechnical Engineering Report
Front Range Colorado Hospitality Project ■ Fort Collins, Colorado
January 20, 2015 ■ Terracon Project No. 20145072
Responsive ■ Resourceful ■ Reliable 14
4.3.3 Spread Footings - Design Recommendations
Description Value
Bearing material
Properly prepared on-site granular soil or
siltstone/sandstone bedrock.
Maximum allowable bearing pressure 1
Siltstone/sandstone: 5,000 psf
On-site granular soil: 2,500 psf
Lateral earth pressure coefficients 2
Active, Ka = 0.27
Passive, Kp = 3.69
At-rest, Ko = 0.43
Sliding coefficient 2 µ = 0.56
Moist soil unit weight ɣ = 130 pcf
Minimum embedment depth below finished
grade 3
30 inches
Estimated total movement 4 About 1 inch
Estimated differential movement 4 About ½ to ¾ of total movement
1. The recommended maximum allowable bearing pressure assumes any unsuitable fill or soft soils,
if encountered, will be over-excavated and replaced with properly compacted engineered fill.
The design bearing pressure applies to a dead load plus design live load condition. The design
bearing pressure may be increased by one-third when considering total loads that include wind or
seismic conditions.
2. The lateral earth pressure coefficients and sliding coefficients are ultimate values and do not
include a factor of safety. The foundation designer should include the appropriate factors of
safety.
3. For frost protection and to reduce the effects of seasonal moisture variations in the subgrade
soils. The minimum embedment depth is for perimeter footings beneath unheated areas and is
relative to lowest adjacent finished grade, typically exterior grade.
4. The estimated movements presented above are based on assumed building loads and
foundation sizes. If shallow footing foundations are selected, we should be contacted to review
our estimated foundation movements based on actual building loads and foundation sizes.
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.
4.3.4 Spread Footings - Construction Considerations
Spread footing foundations bearing partially on soil and partially on very hard bedrock at different
elevations have a higher risk for differential settlement. If the upper level spread footing
Geotechnical Engineering Report
Front Range Colorado Hospitality Project ■ Fort Collins, Colorado
January 20, 2015 ■ Terracon Project No. 20145072
Responsive ■ Resourceful ■ Reliable 15
foundations are extended a minimum of 2 feet deeper than typically constructed for frost
protection, the risk for differential settlement will be reduced and the bearing capacity of the
subgrade may be increased to 3,000 psf. Extending all spread footing foundations to bedrock will
also significantly reduce the risk for differential settlement. However, extending foundations deeper
below grade will increase costs including possible requirements for additional excavation shoring.
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.
4.3.5 Shoring Protection
There are existing site features bordering the project site including existing public roadways,
sidewalks, existing buildings, buried utilities, etc. The excavation for the proposed basement areas
will require a shoring plan to ensure protection for the sidewall slopes. The project design team
should use the subsurface information and laboratory test results contained herein to properly
design a mechanism for shoring purposes.
Shoring should be designed to resist lateral earth pressures to the retained earth and the imposed
loads from adjacent structures and/or structural elements, such as the existing buildings and
associated pavement areas, and the nearby roadways with associated public sidewalks. Shoring
measures could consist of any one of the following concepts or a combination of any: secant
piles/caissons placed on approximate 3-feet centers, sheet piles, soldier beams and lagging, or
tiebacks and bracing. Terracon can provide additional consultation and design recommendations
Geotechnical Engineering Report
Front Range Colorado Hospitality Project ■ Fort Collins, Colorado
January 20, 2015 ■ Terracon Project No. 20145072
Responsive ■ Resourceful ■ Reliable 16
depending upon final design concepts to be utilized by the general contractor based on the
geotechnical conditions present on the site.
4.4 Seismic Considerations
Code Used Site Classification
2012 International Building Code (IBC) 1 C 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 39.3 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 building. If the
floor slab will bear on the siltstone/sandstone bedrock, we recommend the siltstone/sandstone
be over-excavated to a depth of at least 1 foot, and replaced with properly placed engineered
fill. If very little movement can be tolerated, a structurally-supported floor system, supported
independent of the subgrade materials, is recommended. Recommendations for an underslab
drainage system are presented in the 4.1.1 Shallow Groundwater section of this report.
Subgrade soils beneath interior and exterior slabs and at the base of the over-excavation for
removal of siltstone/sandstone bedrock should be scarified to a depth of at least 8 inches,
moisture conditioned and compacted. The moisture content and compaction of subgrade soils
should be maintained until slab construction.
4.5.1 Floor System - Design Recommendations
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. If conventional slab-on-grade is utilized, the subgrade soils
should be over-excavated and prepared as described in the 4.2 Earthwork section of this
report.
For structural design of concrete slabs-on-grade subjected to point loadings, a modulus of
subgrade reaction of 100 pounds per cubic inch (pci) may be used for floors supported on re-
Geotechnical Engineering Report
Front Range Colorado Hospitality Project ■ Fort Collins, Colorado
January 20, 2015 ■ Terracon Project No. 20145072
Responsive ■ Resourceful ■ Reliable 17
compacted existing soils at the site. A modulus of 200 pci may be used for floors supported on
at least 1 foot of non-expansive, imported granular fill.
Additional floor slab design and construction recommendations are as follows:
Positive separations and/or isolation joints should be provided between slabs and all
foundations, columns, or utility lines to allow independent movement.
Control joints should be saw-cut in slabs in accordance with ACI Design Manual,
Section 302.1R-37 8.3.12 (tooled control joints are not recommended) to control the
location and extent of cracking.
Interior utility trench backfill placed beneath slabs should be compacted in accordance
with the recommendations presented in the 4.2 Earthwork section of this report.
Floor slabs should not be constructed on frozen subgrade.
A minimum 1½-inch void space should be constructed below non-bearing partition
walls placed on the floor slab. Special framing details should be provided at
doorjambs and frames within partition walls to avoid potential distortion. Partition walls
should be isolated from suspended ceilings.
The use of a vapor retarder should be considered beneath concrete slabs that will be
covered with wood, tile, carpet or other moisture sensitive or impervious floor
coverings, or when the slab will support equipment sensitive to moisture. When
conditions warrant the use of a vapor retarder, the slab designer and slab contractor
should refer to ACI 302 for procedures and cautions regarding the use and placement
of a vapor retarder.
Other design and construction considerations, as outlined in the ACI Design Manual,
Section 302.1R are recommended.
4.5.2 Floor Systems - Construction Considerations
Movements of slabs-on-grade using the recommendations discussed in previous sections of this
report will likely be reduced and tend to be more uniform. The estimates discussed above
assume that the other recommendations in this report are followed. Additional movement could
occur should the subsurface soils become wetted to significant depths, which could result in
potential excessive movement causing uneven floor slabs and severe cracking. This could be
due to over watering of landscaping, poor drainage, improperly functioning drain systems,
and/or broken utility lines. Therefore, it is imperative that the recommendations presented in
this report be followed.
Geotechnical Engineering Report
Front Range Colorado Hospitality Project ■ Fort Collins, Colorado
January 20, 2015 ■ Terracon Project No. 20145072
Responsive ■ Resourceful ■ Reliable 18
4.6 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
Earth Pressure
Conditions
Coefficient for Backfill
Type
Equivalent Fluid
Density (pcf)
Surcharge
Pressure,
p1 (psf)
Earth
Pressure,
p2 (psf)
Active (Ka)
Granular Material - 0.27
Lean Clay - 0.41
35
49
(0.27)S
(0.41)S
(35)H
(49)H
At-Rest (Ko)
Granular Material - 0.43
Lean Clay - 0.58
56
70
(0.43)S
(0.58)S
(56)H
(70)H
Passive (Kp)
Granular Material - 3.69
Lean Clay - 2.46
480
295
---
---
---
---
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;
Geotechnical Engineering Report
Front Range Colorado Hospitality Project ■ Fort Collins, Colorado
January 20, 2015 ■ Terracon Project No. 20145072
Responsive ■ Resourceful ■ Reliable 19
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 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.
4.7 Pavements
4.7.1 Pavements – Subgrade Preparation
On most project sites, the site grading is accomplished relatively early in the construction phase.
Fills are typically placed and compacted in a uniform manner. However as construction
proceeds, the subgrade may be disturbed due to utility excavations, construction traffic,
desiccation, or rainfall/snow melt. As a result, the pavement subgrade may not be suitable for
pavement construction and corrective action will be required. The subgrade should be carefully
evaluated at the time of pavement construction for signs of disturbance or instability. We
recommend the pavement subgrade be thoroughly proofrolled with a loaded tandem-axle dump
truck prior to final grading and paving. All pavement areas should be moisture conditioned and
properly compacted to the recommendations in this report immediately prior to paving.
4.7.2 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).
Geotechnical Engineering Report
Front Range Colorado Hospitality Project ■ Fort Collins, Colorado
January 20, 2015 ■ Terracon Project No. 20145072
Responsive ■ Resourceful ■ Reliable 20
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 B: Entrance and service lanes with an ADTT of up to 300 over
20 years (Including trash trucks)
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 Thickness (Inches)
Asphaltic
Concrete
Surface
Aggregate
Base
Course
Portland
Cement
Concrete
Total
Automobile Parking
(NAPA Class I and ACI Category A)
A 3½ 6 -- 9½
B -- -- 5½ 5½
Main Traffic Corridors
(NAPA Class II and ACI Category B)
A 4 6 -- 10
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
Geotechnical Engineering Report
Front Range Colorado Hospitality Project ■ Fort Collins, Colorado
January 20, 2015 ■ Terracon Project No. 20145072
Responsive ■ Resourceful ■ Reliable 21
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 specifications or equivalent is
recommended for asphalt concrete. Mix designs should be submitted prior to construction to
verify their adequacy. Asphalt material should be placed in maximum 3-inch lifts and
compacted within a range of 92 to 96 percent of the theoretical maximum (Rice) density (ASTM
D2041).
Where rigid pavements are used, the concrete should be produced from an approved mix
design with the following minimum properties:
Properties Value
Compressive strength 4,000 psi
Cement type Type I or II portland cement
Entrained air content (%) 5 to 8
Concrete aggregate ASTM C33 and CDOT Section 703
Concrete should be deposited by truck mixers or agitators and placed a maximum of 90 minutes
from the time the water is added to the mix. Longitudinal and transverse joints should be
provided as needed in concrete pavements for expansion/contraction and isolation per ACI 325.
The location and extent of joints should be based upon the final pavement geometry. Joints
should be sealed to prevent entry of foreign material and doweled where necessary for load
transfer.
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 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
Geotechnical Engineering Report
Front Range Colorado Hospitality Project ■ Fort Collins, Colorado
January 20, 2015 ■ Terracon Project No. 20145072
Responsive ■ Resourceful ■ Reliable 22
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.
4.7.3 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.
4.7.4 Pavements – Maintenance
Preventative maintenance should be planned and provided for an ongoing pavement
management program in order to enhance future pavement performance. Preventive
maintenance consists of both localized maintenance (e.g. crack and joint sealing and patching)
and global maintenance (e.g. surface sealing). Preventative maintenance is usually the first
priority when implementing a planned pavement maintenance program and provides the highest
return on investment for pavements.
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.
Geotechnical Engineering Report
Front Range Colorado Hospitality Project ■ Fort Collins, Colorado
January 20, 2015 ■ Terracon Project No. 20145072
Responsive ■ Resourceful ■ Reliable 23
The analysis and recommendations presented in this report are based upon the data obtained
from the borings performed at the indicated locations and from other information discussed in
this report. This report does not reflect variations that may occur between borings, across the
site, or due to the modifying effects of construction or weather. The nature and extent of such
variations may not become evident until during or after construction. If variations appear, we
should be immediately notified so that further evaluation and supplemental recommendations
can be provided.
The scope of services for this project does not include either specifically or by implication any
environmental or biological (e.g., mold, fungi, and bacteria) assessment of the site or
identification or prevention of pollutants, hazardous materials or conditions. If the owner is
concerned about the potential for such contamination or pollution, other studies should be
undertaken.
This report has been prepared for the exclusive use of our client for specific application to the
project discussed and has been prepared in accordance with generally accepted geotechnical
engineering practices. No warranties, either express or implied, are intended or made. Site
safety, excavation support, and dewatering requirements are the responsibility of others. In the
event that changes in the nature, design, or location of the project as described in this report are
planned, the conclusions and recommendations contained in this report shall not be considered
valid unless Terracon reviews the changes and either verifies or modifies the conclusions of this
report in writing.
APPENDIX A
FIELD EXPLORATION
SITE LOCATION MAP
Front Range Colorado Hospitality Project
354 Walnut Street
Fort Collins, CO
TOPOGRAPHIC MAP IMAGE COURTESY OF THE U.S. GEOLOGICAL SURVEY
QUADRANGLES INCLUDE: FORT COLLINS, CO (1/1/1984).
1901 Sharp Point Dr Suite C
Ft. Collins, CO 80525
20145072
Project Manager:
Drawn by:
Checked by:
Approved by:
BCR
EDB
EDB
1:24,000
1/13/2014
Project No.
Scale:
File Name:
Date: A-1
EDB Exhibit
1
2
3
4
5
6
DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT
INTENDED FOR CONSTRUCTION PURPOSES
A-2
Project Manager: EXPLORATION PLAN EXHIBIT
Drawn By:
Check By:
Approved By:
EDB
BCR
EDB
EDB
Project No.
Scale:
File Name:
Date:
20145072
1”=100
’
1/20/2014
0’ 50’ 100’
APPROXIMATE SCALE
LEGEND
Approximate Boring Location
1
Approximate Location of Temporary Benchmark
(Rim of sanitary sewer–Elevation 4976.5’)
Front Range Colorado Hospitality Project
354 Walnut Street
Fort Collins, CO
1901 Sharp Point Dr Suite C
Ft. Collins, CO 80525
Geotechnical Engineering Report
Front Range Colorado Hospitality Project ■ Fort Collins, Colorado
January 20, 2015 ■ Terracon Project No. 20145072
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-55 and CME-75 truck-mounted rotary drill rig with solid-
stem and hollow-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. 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 split-spoon sampler 18 inches, 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.
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. Four (4) of the borings were converted to temporary piezometers for
future groundwater measurements. The remaining 2 borings were backfilled with auger cuttings
and sand (if needed) and patched. Some settlement of the backfill and/or patch may occur and
should be repaired as soon as possible.
0.3
0.7
2.0
10.0
39.2
ASPHALT PAVEMENT - 3 inches
AGGREGATE BASE COURSE - 5 inches
FILL - SANDY LEAN CLAY , trace gravel, brown
WELL GRADED SAND WITH SILT, GRAVEL,
AND COBBLES, fine to coarse grained, brown,
medium dense to very dense
INTERBEDDED SEDIMENTARY BEDROCK -
SILtSTONE/SANDSTONE, fine grained, olive
rust to gray, very hard
A very hard cemented lense was encountered
from a depth of 10 to 11.5 feet below the existing
site grades.
Boring Terminated at 39.2 Feet
2
1
13
10
16
32-26-6
10
50
Well cap
Bentonite seal
Slough
backfill
around pipe.
Slough
backfill
around slotted
pipe.
4976.5
4976
4975
4967
4937.5
5-33-26
N=59
14-11-9
N=20
50/6"
N=50/6"
26-50/3"
N=76/9"
50/4"
N=50/4"
50/2"
N=50/2"
50/2"
N=50/2"
Stratification lines are approximate. In-situ, the transition may be gradual.
DEPTH
LOCATION: See Exhibit A-2
GRAPHIC LOG
Hammer Type: Automatic
Latitude: 40.587666° Longitude: -105.074424°
0.3
0.7
7.0
9.0
34.2
ASPHALT PAVEMENT - 2.5 inches
AGGREGATE BASE COURSE - 4 inches
FILL - SANDY LEAN CLAY (CL), trace gravel,
light brown, stiff
WELL GRADED SAND WITH SILT, GRAVEL,
AND COBBLES, fine to coarse grained, brown,
medium dense
INTERBEDDED SEDIMENTARY BEDROCK -
SILtSTONE/SANDSTONE, with silt, fine
grained, olive rust to gray, hard to very hard
Boring Terminated at 34.2 Feet
18
13
2
17
13
12
10
34-19-15 58
54
Well cap
Bentonite seal
Slough
backfill
around pipe.
Slough
backfill
around slotted
pipe.
4976.5
4976
4969.5
4967.5
4942.5
2-4-7
N=11
6-6-6
N=12
17-31-28
N=59
35-50/5"
N=85/11"
50/4"
N=50/4"
50/3"
N=50/3"
50/2"
N=50/2"
Stratification lines are approximate. In-situ, the transition may be gradual.
DEPTH
LOCATION: See Exhibit A-2
GRAPHIC LOG
Hammer Type: Automatic
Latitude: 40.587908° Longitude: -105.074117°
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-WELL 20145072.GPJ TERRACON2012.GDT 1/20/15
0.2
0.5
3.5
13.0
29.2
ASPHALT PAVEMENT - 2 inches
AGGREGATE BASE COURSE - 4 inches
FILL - SANDY LEAN CLAY , trace gravel, brown to light brown, stiff
SILTY SAND WITH GRAVEL AND COBBLES (SM), fine to coarse
grained, brown, dense to very dense
INTERBEDDED SEDIMENTARY BEDROCK - SILtSTONE/SANDSTONE,
with silt, fine grained, olive rust to gray, very hard
A very hard cemented lense was encountered from a depth of 13 to 14.3 feet
below the existing site grades.
Boring Terminated at 29.2 Feet
2-3-6
N=9
8-22-22
N=44
18-50/6"
N=68"
21-50/6"
N=71"
50/5"
N=50/5"
50/4"
N=50/4"
50/2"
N=50/2"
16
8
12
3
12
19
20
19
NP
4975.5
4975.5
4972.5
4963
4946.5
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
LOCATION
DEPTH
Latitude: 40.587676° Longitude: -105.074123°
GRAPHIC LOG
See Exhibit A-2
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20145072.GPJ TERRACON2012.GDT 1/20/15
354 Walnut Street
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
4.25 inch hollow-stem augers
Abandonment Method:
Borings backfilled with soil cuttings upon completion.
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
0.3
1.1
4.0
9.0
39.3
ASPHALT PAVEMENT - 3 inches
AGGREGATE BASE COURSE - 8 inches
FILL - SANDY LEAN CLAY , trace gravel,
brown, stiff
WELL GRADED SAND WITH SILT, GRAVEL,
AND COBBLES, fine to coarse grained, brown,
very dense
INTERBEDDED SEDIMENTARY BEDROCK -
SILtSTONE/SANDSTONE (SM), with silt, fine
grained, olive rust to gray, very hard
A very hard cemented lense was encountered
from a depth of 9 to 11 feet below the existing site
grades.
Boring Terminated at 39.3 Feet
10
1
2
14
20
20
19
18
NP 41
Well cap
Bentonite seal
Slough
backfill
around pipe.
Slough
backfill
around slotted
pipe.
4976
4975.5
4972.5
4967.5
4937
7-6-4
N=10
4-32-40
N=72
50/5"
N=50/5"
42-50/6"
N=92
50/6"
N=50/6"
50/5"
N=50/5"
50/3"
N=50/3"
50/3"
N=50/3"
Stratification lines are approximate. In-situ, the transition may be gradual.
DEPTH
0.3
0.7
5.0
10.0
34.2
ASPHALT PAVEMENT - 4 inches
AGGREGATE BASE COURSE - 4 inches
FILL - CLAYEY SAND (SC), trace gravel,
reddish-brown, medium dense
WELL GRADED SAND WITH SILT, GRAVEL,
AND COBBLES, fine to coarse grained, light
brown, very dense
INTERBEDDED SEDIMENTARY BEDROCK -
SILtSTONE/SANDSTONE, with silt, fine
grained, olive rust to gray, very hard
Boring Terminated at 34.2 Feet
13
2
2
13
14
14
13
26-17-9 41
Well cap
Bentonite seal
Slough
backfill
around pipe.
Slough
backfill
around slotted
pipe.
4974
4973.5
4969.5
4964.5
4940
7-8-13
N=21
7-16-26
N=42
50/3"
N=50/3"
50/5"
N=50/5"
50/3"
N=50/3"
50/3"
N=50/3"
50/2"
N=50/2"
Stratification lines are approximate. In-situ, the transition may be gradual.
DEPTH
LOCATION: See Exhibit A-2
GRAPHIC LOG
Hammer Type: Automatic
Latitude: 40.587679° Longitude: -105.073678°
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-WELL 20145072.GPJ TERRACON2012.GDT 1/20/15
354 Walnut Street
0.3
0.8
12.0
29.2
ASPHALT PAVEMENT - 4 inches
AGGREGATE BASE COURSE - 6 inches
WELL GRADED SAND WITH SILT, GRAVEL, AND COBBLES, fine to
coarse grained, brown, dense to very dense
INTERBEDDED SEDIMENTARY BEDROCK - SILtSTONE/SANDSTONE,
with silt, fine grained, gray, very hard
A very hard cemented lense was encountered from a depth of 14 to 15 feet
below the existing site grades.
Boring Terminated at 29.2 Feet
14-16-19
N=35
20-20-26
N=46
18-22-32
N=54
50/2"
N=50/2"
50/3"
N=50/3"
50/2"
N=50/2"
3
3
3
14
13
4974.5
4974
4962.5
4945.5
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
LOCATION
DEPTH
Latitude: 40.587921° Longitude: -105.073745°
GRAPHIC LOG
See Exhibit A-2
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20145072.GPJ TERRACON2012.GDT 1/20/15
354 Walnut Street
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
4.25 inch hollow-stem augers
Abandonment Method:
Borings backfilled with soil cuttings upon completion.
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
Notes:
Project No.: 20145072
Drill Rig: CME-55
Boring Started: 1/14/2015
BORING LOG NO. 6
CLIENT: McWhinney Real Estate Services, Inc.
Loveland, Colorado
Driller: Unlimited Access Drilling
Boring Completed: 1/14/2015
APPENDIX B
LABORATORY TESTING
Geotechnical Engineering Report
Front Range Colorado Hospitality Project ■ Fort Collins, Colorado
January 20, 2015 ■ Terracon Project No. 20145072
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
Water-soluble sulfate content
Dry density
v
0 v
10
20
30
40
50
60
0 20 40 60 80 100
CL or OL CH or OH
ML or OL
MH or OH
PL PI
14.0
2.0
9.0
14.0
2.0
Boring ID Depth Description
SANDY SILT
SANDY LEAN CLAY
SILTY SAND with GRAVEL
SILTY SAND
CLAYEY SAND
ML
CL
SM
SM
SC
Fines
P
L
A
S
T
I
C
I
T
Y
I
N
D
E
X
LIQUID LIMIT
"U" Line
"A" Line
32
34
NP
31
26
26
19
NP
39
17
6
15
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
100 10 1 0.1 0.01 0.001
6 8
10
50.4
57.9
15.6
41.1
5.0
1.2
38.7
2.1
14
LL PL PI
%Silt %Clay
1 4
3/4 1/2
60
fine
U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS HYDROMETER
6 16
20 30
40 50
1.5 200
26
19
NP
17
6
15
NP
9
D100
Cc Cu
SILT OR CLAY
4
D30 D10 %Gravel %Sand
1
2
3
APPENDIX C
SUPPORTING DOCUMENTS
Exhibit: C-1
Unconfined
Compressive
Strength
Qu, (tsf)
0.25 to 0.50
1.00 to 2.00
> 4.00
less than 0.25
0.50 to 1.00
2.00 to 4.00
Non-plastic
Low
Medium
High
DESCRIPTION OF SYMBOLS AND ABBREVIATIONS
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
UNIFIED SOIL CLASSIFICATION SYSTEM
Exhibit C-2
Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A
Soil Classification
Group
Symbol Group Name B
Coarse Grained Soils:
More than 50% retained
on No. 200 sieve
Gravels:
More than 50% of
coarse fraction retained
on No. 4 sieve
Clean Gravels:
Less than 5% fines C
Cu 4 and 1 Cc 3 E GW Well-graded gravel F
Cu 4 and/or 1 Cc 3 E GP Poorly graded gravel F
Gravels with Fines:
More than 12% fines C
Fines classify as ML or MH GM Silty gravel F,G,H
Fines classify as CL or CH GC Clayey gravel F,G,H
Sands:
50% or more of coarse
fraction passes No. 4
sieve
Clean Sands:
Less than 5% fines D
Cu 6 and 1 Cc 3 E SW Well-graded sand I
Cu 6 and/or 1 Cc 3 E SP Poorly graded sand I
Sands with Fines:
More than 12% fines D
Fines classify as ML or MH SM Silty sand G,H,I
Fines classify as CL or CH SC Clayey sand G,H,I
Fine-Grained Soils:
50% or more passes the
No. 200 sieve
Silts and Clays:
Liquid limit less than 50
Inorganic:
PI 7 and plots on or above “A” line J CL Lean clay K,L,M
PI 4 or plots below “A” line J ML Silt K,L,M
Organic:
Liquid limit - oven dried
0.75 OL
Organic clay K,L,M,N
Liquid limit - not dried Organic silt K,L,M,O
Silts and Clays:
Liquid limit 50 or more
Inorganic:
PI plots on or above “A” line CH Fat clay K,L,M
PI plots below “A” line MH Elastic Silt K,L,M
Organic:
Liquid limit - oven dried
0.75 OH
Organic clay K,L,M,P
Liquid limit - not dried Organic silt K,L,M,Q
Highly organic soils: Primarily organic matter, dark in color, and organic odor PT Peat
A Based on the material passing the 3-inch (75-mm) sieve
B If field sample contained cobbles or boulders, or both, add “with cobbles
or boulders, or both” to group name.
DESCRIPTION OF ROCK PROPERTIES
Exhibit C-3
WEATHERING
Fresh Rock fresh, crystals bright, few joints may show slight staining. Rock rings under hammer if crystalline.
Very slight Rock generally fresh, joints stained, some joints may show thin clay coatings, crystals in broken face show
bright. Rock rings under hammer if crystalline.
Slight Rock generally fresh, joints stained, and discoloration extends into rock up to 1 in. Joints may contain clay. In
granitoid rocks some occasional feldspar crystals are dull and discolored. Crystalline rocks ring under hammer.
Moderate Significant portions of rock show discoloration and weathering effects. In granitoid rocks, most feldspars are dull
and discolored; some show clayey. Rock has dull sound under hammer and shows significant loss of strength
as compared with fresh rock.
Moderately severe All rock except quartz discolored or stained. In granitoid rocks, all feldspars dull and discolored and majority
show kaolinization. Rock shows severe loss of strength and can be excavated with geologist’s pick.
Severe All rock except quartz discolored or stained. Rock “fabric” clear and evident, but reduced in strength to strong
soil. In granitoid rocks, all feldspars kaolinized to some extent. Some fragments of strong rock usually left.
Very severe All rock except quartz discolored or stained. Rock “fabric” discernible, but mass effectively reduced to “soil” with
only fragments of strong rock remaining.
Complete Rock reduced to ”soil”. Rock “fabric” not discernible or discernible only in small, scattered locations. Quartz may
be present as dikes or stringers.
HARDNESS (for engineering description of rock – not to be confused with Moh’s scale for minerals)
Very hard Cannot be scratched with knife or sharp pick. Breaking of hand specimens requires several hard blows of
geologist’s pick.
Hard Can be scratched with knife or pick only with difficulty. Hard blow of hammer required to detach hand specimen.
Moderately hard Can be scratched with knife or pick. Gouges or grooves to ¼ in. deep can be excavated by hard blow of point of
a geologist’s pick. Hand specimens can be detached by moderate blow.
Medium Can be grooved or gouged 1/16 in. deep by firm pressure on knife or pick point. Can be excavated in small
chips to pieces about 1-in. maximum size by hard blows of the point of a geologist’s pick.
Soft Can be gouged or grooved readily with knife or pick point. Can be excavated in chips to pieces several inches in
size by moderate blows of a pick point. Small thin pieces can be broken by finger pressure.
Very soft Can be carved with knife. Can be excavated readily with point of pick. Pieces 1-in. or more in thickness can be
broken with finger pressure. Can be scratched readily by fingernail.
Joint, Bedding, and Foliation Spacing in Rock
a
Spacing Joints Bedding/Foliation
Less than 2 in. Very close Very thin
2 in. – 1 ft. Close Thin
1 ft. – 3 ft. Moderately close Medium
3 ft. – 10 ft. Wide Thick
More than 10 ft. Very wide Very thick
a. Spacing refers to the distance normal to the planes, of the described feature, which are parallel to each other or nearly so.
Rock Quality Designator (RQD) a Joint Openness Descriptors
RQD, as a percentage Diagnostic description Openness Descriptor
Exceeding 90 Excellent No Visible Separation Tight
90 – 75 Good Less than 1/32 in. Slightly Open
75 – 50 Fair 1/32 to 1/8 in. Moderately Open
50 – 25 Poor 1/8 to 3/8 in. Open
Less than 25 Very poor 3/8 in. to 0.1 ft. Moderately Wide
a. RQD (given as a percentage) = length of core in pieces Greater than 0.1 ft. Wide
4 in. and longer/length of run.
References: American Society of Civil Engineers. Manuals and Reports on Engineering Practice - No. 56. Subsurface Investigation for
Design and Construction of Foundations of Buildings. New York: American Society of Civil Engineers, 1976. U.S.
Department of the Interior, Bureau of Reclamation, Engineering Geology Field Manual.
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
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.
Design
Soluble Sulfate
Used to determine the quantitative amount of soluble
sulfates within a soil mass.
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
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.
Gravel
Sand
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
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
BEDROCK
Loose
Medium Dense
Dense
0 - 3
4 - 9
10 - 29
30 - 50
7 - 18
19 - 58
Very Soft
Soft
Medium-Stiff
Stiff
Very Stiff
Standard
Penetration or
N-Value
Blows/Ft.
2 - 4
4 - 8
8 - 15
< 3
5 - 9
19 - 42
> 42
30 - 49
50 - 89
20 - 29
Medium Hard
Very Dense
RELATIVE DENSITY OF COARSE-GRAINED
SOILS
Descriptive
Term
(Density)
Very Loose
> 50
Ring
Sampler
Blows/Ft.
0 - 6
59 - 98
> 99
Descriptive
Term
(Consistency)
Hard
0 - 1
Ring
Sampler
Blows/Ft.
3 - 4
10 - 18
Ring
Sampler
Blows/Ft.
< 30
90 - 119
Standard
Penetration or
N-Value
Blows/Ft.
Descriptive
Term
(Consistency)
Weathered
Firm
Very Hard
CONSISTENCY OF FINE-GRAINED SOILS
(More than 50% retained on No. 200 sieve.)
Density determined by
Standard Penetration Resistance
(50% or more passing the No. 200 sieve.)
Consistency determined by laboratory shear strength testing, field
visual-manual procedures or standard penetration resistance
Standard
Penetration or
N-Value
Blows/Ft.
_ 15 - 30
> 30
> 119
< 20
30 - 49
50 - 79
>79
Hard
5
SANDY SILT(ML)
SANDY LEAN CLAY(CL)
SILTY SAND with GRAVEL(SM)
CLAYEY SAND(SC)
32
34
NP
26
0.363
0.114
0.087
4.305
0.141
9.5
9.5
25
9.5
1
2
3
5
14.0
2.0
9.0
2.0
GRAIN SIZE IN MILLIMETERS
PERCENT FINER BY WEIGHT
coarse fine
3/8 3 100
3 2 140
COBBLES
GRAVEL SAND
USCS Classification
44.7
40.9
45.7
56.7
D60
coarse medium
14.0
2.0
9.0
2.0
Boring ID Depth
Boring ID Depth
GRAIN SIZE DISTRIBUTION
ASTM D422
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
PROJECT NUMBER: 20145072
PROJECT: Front Range Colorado Hospitality
Project
SITE: 354 Walnut Street
Fort Collins, Colorado
CLIENT: McWhinney Real Estate Services,
Inc.
Loveland, Colorado
EXHIBIT: B-3
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GRAIN SIZE: USCS-2 20145072.GPJ TERRACON2012.GDT 1/20/15
NP
NP
9
50
58
16
41
41
LL USCS
1
2
3
4
5
ATTERBERG LIMITS RESULTS
ASTM D4318
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
PROJECT NUMBER: 20145072
PROJECT: Front Range Colorado Hospitality
Project
SITE: 354 Walnut Street
Fort Collins, Colorado
CLIENT: McWhinney Real Estate Services,
Inc.
Loveland, Colorado
EXHIBIT: B-2
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. ATTERBERG LIMITS 20145072.GPJ TERRACON2012.GDT 1/20/15
CL-ML
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: Front Range Colorado Hospitality Project
FIELD TEST
RESULTS
PERCENT FINES
WATER
CONTENT (%)
ATTERBERG
LIMITS
LL-PL-PI
Surface Elev.: 4974.6 (Ft.)
ELEVATION (Ft.)
SAMPLE TYPE
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
15
20
25
No free water observed
WATER LEVEL OBSERVATIONS
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
4.25 inch hollow-stem augers
Abandonment Method:
Boring converted to temporary piezometer
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
Notes:
Project No.: 20145072
Drill Rig: CME-55
Boring Started: 1/14/2015
BORING LOG NO. 5
CLIENT: McWhinney Real Estate Services, Inc.
Loveland, Colorado
Driller: Unlimited Access Drilling
Boring Completed: 1/14/2015
Exhibit: A-8
See Exhibit A-3 for description of field
procedures.
See Appendix B for description of laboratory
procedures and additional data (if any).
See Appendix C for explanation of symbols and
abbreviations.
PROJECT: Front Range Colorado Hospitality Project
WATER
CONTENT (%)
ATTERBERG
LIMITS
LL-PL-PI
PERCENT FINES
WATER LEVEL
OBSERVATIONS
INSTALLATION
DETAILS
SAMPLE TYPE
DEPTH (Ft.)
5
10
15
20
25
30
Surface Elev.: 4974.3 (Ft.)
ELEVATION (Ft.)
FIELD TEST
RESULTS
No free water observed
WATER LEVEL OBSERVATIONS
LOCATION: See Exhibit A-2
GRAPHIC LOG
Hammer Type: Automatic
Latitude: 40.587521° Longitude: -105.074179°
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-WELL 20145072.GPJ TERRACON2012.GDT 1/20/15
354 Walnut Street
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
4.25 inch hollow-stem augers
Abandonment Method:
Boring converted to temporary piezometer
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
Notes:
Project No.: 20145072
Drill Rig: CME-55
Boring Started: 1/9/2015
BORING LOG NO. 4
CLIENT: McWhinney Real Estate Services, Inc.
Loveland, Colorado
Driller: Unlimited Access Drilling
Boring Completed: 1/13/2015
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: Front Range Colorado Hospitality Project
WATER
CONTENT (%)
ATTERBERG
LIMITS
LL-PL-PI
PERCENT FINES
WATER LEVEL
OBSERVATIONS
INSTALLATION
DETAILS
SAMPLE TYPE
DEPTH (Ft.)
5
10
15
20
25
30
35
Surface Elev.: 4976.5 (Ft.)
ELEVATION (Ft.)
FIELD TEST
RESULTS
While drilling
WATER LEVEL OBSERVATIONS
Notes:
Project No.: 20145072
Drill Rig: CME-55
Boring Started: 1/13/2015
BORING LOG NO. 3
CLIENT: McWhinney Real Estate Services, Inc.
Loveland, Colorado
Driller: Unlimited Access Drilling
Boring Completed: 1/13/2015
Exhibit: A-6
See Exhibit A-3 for description of field
procedures.
See Appendix B for description of laboratory
procedures and additional data (if any).
See Appendix C for explanation of symbols and
abbreviations.
PROJECT: Front Range Colorado Hospitality Project
FIELD TEST
RESULTS
PERCENT FINES
WATER
CONTENT (%)
ATTERBERG
LIMITS
LL-PL-PI
Surface Elev.: 4975.9 (Ft.)
ELEVATION (Ft.)
SAMPLE TYPE
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
15
20
25
No free water observed
WATER LEVEL OBSERVATIONS
354 Walnut Street
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
4.25 inch hollow-stem augers
Abandonment Method:
Boring converted to temporary piezometer
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
Notes:
Project No.: 20145072
Drill Rig: CME-55
Boring Started: 1/16/2015
BORING LOG NO. 2
CLIENT: McWhinney Real Estate Services, Inc.
Loveland, Colorado
Driller: Unlimited Access Drilling
Boring Completed: 1/16/2015
Exhibit: A-5
See Exhibit A-3 for description of field
procedures.
See Appendix B for description of laboratory
procedures and additional data (if any).
See Appendix C for explanation of symbols and
abbreviations.
PROJECT: Front Range Colorado Hospitality Project
WATER
CONTENT (%)
ATTERBERG
LIMITS
LL-PL-PI
PERCENT FINES
WATER LEVEL
OBSERVATIONS
INSTALLATION
DETAILS
SAMPLE TYPE
DEPTH (Ft.)
5
10
15
20
25
30
Surface Elev.: 4976.6 (Ft.)
ELEVATION (Ft.)
FIELD TEST
RESULTS
No free water observed
WATER LEVEL OBSERVATIONS
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-WELL 20145072.GPJ TERRACON2012.GDT 1/20/15
354 Walnut Street
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
4.25 inch hollow-stem augers
Abandonment Method:
Boring converted to temporary piezometer
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
Notes:
Project No.: 20145072
Drill Rig: CME-55
Boring Started: 1/16/2015
BORING LOG NO. 1
CLIENT: McWhinney Real Estate Services, Inc.
Loveland, Colorado
Driller: Unlimited Access Drilling
Boring Completed: 1/16/2015
Exhibit: A-4
See Exhibit A-3 for description of field
procedures.
See Appendix B for description of laboratory
procedures and additional data (if any).
See Appendix C for explanation of symbols and
abbreviations.
PROJECT: Front Range Colorado Hospitality Project
WATER
CONTENT (%)
ATTERBERG
LIMITS
LL-PL-PI
PERCENT FINES
WATER LEVEL
OBSERVATIONS
INSTALLATION
DETAILS
SAMPLE TYPE
DEPTH (Ft.)
5
10
15
20
25
30
35
Surface Elev.: 4976.8 (Ft.)
ELEVATION (Ft.)
FIELD TEST
RESULTS
While drilling
1/19/14
WATER LEVEL OBSERVATIONS