HomeMy WebLinkAboutFOSSIL CREEK APARTMENTS (FORMERLY WATERSTONE APARTMENTS) - PDP - PDP170010 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTPreliminary Geotechnical
Engineering Report
Goldelm at Fossil Creek
Northwest of South College Avenue and Crestridge Drive
Fort Collins, Colorado
April 14, 2015
Terracon Project No. 20155011
Prepared for:
GOLDELM Apartments
Lakeside, Montana
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 PRELIMINARY RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION ............ 3
4.1 Preliminary Geotechnical Considerations ............................................................ 3
4.1.1 Expansive Soils ....................................................................................... 4
4.1.2 Sandstone Bedrock ................................................................................. 4
4.1.3 Preliminary Foundation Recommendations ............................................. 4
4.2 Earthwork ........................................................................................................... 5
4.2.1 Site Preparation........................................................................................ 5
4.2.2 Excavation ............................................................................................... 5
4.2.3 Subgrade Preparation .............................................................................. 6
4.2.4 Fill Materials and Placement ..................................................................... 7
4.2.5 Compaction Requirements ....................................................................... 8
4.2.6 Utility Trench Backfill ............................................................................... 9
4.2.7 Grading and Drainage .............................................................................. 9
4.2.8 Exterior Slab Design and Construction ...................................................10
4.2.9 Corrosion Protection ...............................................................................10
4.3 Preliminary Foundation Recommendations ..........................................................10
4.3.1 Post-Tensioned Slabs – Preliminary Design Recommendations .............10
4.3.3 Spread Footings – Preliminary Design Recommendations .....................11
4.4 Seismic Considerations......................................................................................11
4.5 Floor Systems ....................................................................................................12
4.5.1 Floor System - Preliminary Design Recommendations ...........................12
4.6 Swimming Pool - Preliminary Recommendations ...............................................12
4.7 Preliminary Pavements ......................................................................................12
4.7.1 Pavements – Subgrade Preparation .......................................................12
4.7.2 Pavements – Preliminary Design Recommendations .............................13
4.7.3 Pavements – Construction Considerations .............................................15
4.7.4 Pavements – Maintenance .....................................................................15
5.0 GENERAL COMMENTS ...............................................................................................16
TABLE OF CONTENTS (continued)
Appendix A – FIELD EXPLORATION
Exhibit A-1 Site Location Map
Exhibit A-2 Exploration Plan
Exhibit A-3 Field Exploration Description
Exhibits A-4 to A-10 Boring Logs
Appendix B – LABORATORY TESTING
Exhibit B-1 Laboratory Testing Description
Exhibit B-2 Atterberg Limits Test Results
Exhibit B-3 Grain-size Distribution Test Results
Exhibits B-4 and B-5 Swell-consolidation Test Results
Exhibit B-6 Corrosion 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
Preliminary Geotechnical Engineering Report
Goldelm at Fossil Creek ■ Fort Collins, Colorado
April 14, 2015 ■ Terracon Project No. 20155011
Responsive ■ Resourceful ■ Reliable i
EXECUTIVE SUMMARY
A preliminary geotechnical investigation has been performed for the proposed Goldelm at Fossil
Creek apartments to be constructed northwest of South College Avenue and Crestridge Drive in
Fort Collins, Colorado. Seven (7) borings, presented as Exhibits A-4 through A-10 and designated
as Boring No. 1 through Boring No. 7, were performed to depths of approximately 15 to 25 feet below
existing site grades. This report specifically addresses the preliminary recommendations for the
proposed apartment buildings, swimming pool, clubhouse, and associate pavements. Borings
performed in these areas are for informational purposes and will be utilized by others.
Based on the information obtained from our preliminary subsurface exploration, the site can be
developed for the proposed project. However, the following geotechnical considerations were
identified and will need to be considered:
Supplementary geotechnical engineering exploration should be performed at the site
upon completion of initial design studies in order to confirm or modify the
recommendations contained in this preliminary report and to allow the development of
recommendations more specific to the proposed construction.
The proposed buildings may be supported on shallow foundation systems bearing on
properly prepared on-site soils, newly placed engineered fill, and/or sandstone bedrock.
We understand spread footing foundation and post-tensioned slab foundations are being
considered as possible foundation systems for the proposed structures.
A slab-on-grade floor system is recommended for the proposed buildings. If post-tensioned
slabs are chosen as the foundations system, the foundations will function as the floor-slabs.
On-site soils are suitable for use as engineered fill.
If the proposed building foundations will be supported partially on soil and partially on
sandstone bedrock, we recommend over-excavating to a depth of 2 feet below the design
bearing level where bedrock is present below foundations. The over-excavation should be
backfilled with approved materials. The purpose of the over-excavation is to reduce
differential settlement due to differing bearing materials.
Hard to very hard sandstone bedrock was encountered in the borings completed at this site
at depths of about ½ to 19 feet below the existing site grades. Excavation for site
development, foundations, and utilities into the sandstone bedrock underlying this site will
require greater efforts including ripping, and/or jackhammering procedures to achieve
desired grades.
The 2012 International Building Code, Table 1613.5.2 IBC seismic site classification for this
site is D.
Preliminary Geotechnical Engineering Report
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Close monitoring of the construction operations discussed herein will be critical in achieving
the design subgrade support. We therefore recommend that Terracon be retained to
monitor this portion of the work.
This summary should be used in conjunction with the entire report for design purposes. It should
be recognized that details were not included or fully developed in this section, and the report must
be read in its entirety for a comprehensive understanding of the items contained herein. The section
titled GENERAL COMMENTS should be read for an understanding of the report limitations.
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PRELIMINARY GEOTECHNICAL ENGINEERING REPORT
Goldelm at Fossil Creek
Northwest of South College Avenue and Crestridge Drive
Fort Collins, Colorado
Terracon Project No. 20155011
April 14, 2015
1.0 INTRODUCTION
This preliminary report presents the results of our preliminary geotechnical engineering services
performed for the proposed Goldelm at Fossil Creek apartments to be located northwest of South
College Avenue and Crestridge Drive in Fort Collins, Colorado. The purpose of these services is
to provide information and preliminary 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 preliminary geotechnical engineering scope of work for this project included the initial site
visit, the advancement of seven test borings to depths ranging from approximately 15 to 25 feet
below existing site grades, laboratory testing for soil engineering properties and engineering
analyses to provide foundation, floor system and pavement design and construction
recommendations.
Logs of the borings along with an Exploration Plan (Exhibit A-2) are included in Appendix A. The
results of the laboratory testing performed on soil and bedrock samples obtained from the site
during the field exploration are included in Appendix B.
2.0 PROJECT INFORMATION
2.1 Project Description
Item Description
Site layout Refer to the Exploration Plan (Exhibit A-2 in Appendix A)
Proposed construction
We understand the proposed development will include apartment
buildings with a clubhouse, swimming pool, and detached garages.
There will be eleven 3-story apartment buildings likely constructed
on post-tensioned slab foundation systems or possibly on spread
footings.
Preliminary Geotechnical Engineering Report
Goldelm at Fossil Creek ■ Fort Collins, Colorado
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Item Description
Building construction We anticipate the buildings will be wood-framed structures.
Maximum loads
Columns: 100 kips (assumed)
Walls: 3 klf (assumed)
Slabs: 150 psf max (assumed)
Grading
We anticipate cuts and fills of up to about 10 feet may be required
for portion of the site.
Cut and fill slopes Assumed to be no steeper than 3H:1V (Horizontal to Vertical)
Retaining walls
We have not been requested to provide geotechnical
recommendations for a retaining wall system at this site. We are
available to assist with the subsurface exploration and/or design of
earth retaining structures being considered as part of the site
development.
Below-grade areas
No below-grade areas are planned excluding the outdoor swimming
pool.
Traffic loading
We anticipate traffic loading will consist primarily of passenger
vehicles with drive lanes accommodating refuse disposal vehicles,
moving vehicles, and delivery trucks.
2.2 Site Location and Description
Item Description
Location
The approximately 12.34-acre site is located northwest of the
intersection of South College Avenue and Crestridge Drive in Fort
Collins, Colorado.
Existing improvements
Office and retail development is to the east, vacant land is to the
west with the Burlington Northern Railroad and residential
development beyond, Fossil Creek is to the north with vacant land
beyond, and a car dealership is to the south with residential
development beyond.
Current ground cover
The ground surface is covered with native grasses and weeds as
well as some walking trails.
Existing topography
A ridge is located near the southern portion of the site. The site
slopes from the ridge down to the south and to the north towards
Fossil Creek. The grading plan provided to us indicates total relief
across the site of about 40 feet.
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
Preliminary Geotechnical Engineering Report
Goldelm at Fossil Creek ■ Fort Collins, Colorado
April 14, 2015 ■ Terracon Project No. 20155011
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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
Lean clay with varying amounts of
sand
About 15 feet below existing
site grades in Boring No. 1 only.
Stiff to very stiff
Sand with varying amounts of silt
and gravel
About 1 to 19 feet below
existing site grades.
Loose to medium dense
Sandstone bedrock
To the maximum depth of
exploration of about 25 feet.
Hard to very hard
3.2 Laboratory Testing
Representative soil samples were selected for swell-consolidation testing and exhibited 2.9 to 1.5
percent compression when wetted. The sandstone bedrock is considered to be non-expansive.
Samples of site soils and bedrock selected for plasticity testing exhibited low to medium plasticity
with liquid limits ranging from non-plastic to 32 and plasticity indices of 17. 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. Groundwater was not observed in the borings while drilling, or for the short duration
that the borings were allowed to remain open.
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 than
the levels indicated on the boring logs. The possibility of groundwater level fluctuations should
be considered when developing the design and construction plans for the project.
4.0 PRELIMINARY RECOMMENDATIONS FOR DESIGN AND
CONSTRUCTION
4.1 Preliminary Geotechnical Considerations
The preliminary recommendations presented in this report are based on the assumption that the
subsurface conditions encountered in the widely spaced preliminary borings provide an accurate
representation of the entire site. Supplementary geotechnical engineering exploration should be
performed at the site upon completion of initial design studies in order to confirm or modify the
Preliminary Geotechnical Engineering Report
Goldelm at Fossil Creek ■ Fort Collins, Colorado
April 14, 2015 ■ Terracon Project No. 20155011
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recommendations contained in this preliminary report and to allow the development of
recommendations more specific to the proposed construction.
4.1.1 Expansive Soils
Laboratory testing indicates the native soils exhibited 2.9 to 1.5 percent compression at the
samples in-situ moisture content. However, it is our opinion these materials will exhibit a higher
expansive potential if the clays undergo a significant loss of moisture.
This report provides recommendations to help mitigate the effects of soil shrinkage and
expansion. However, even if these procedures are followed, some movement and cracking in
the structures, pavements, and flatwork should be anticipated. The severity of cracking and other
damage such as uneven floor slabs will probably increase if any modification of the site results in
excessive wetting or drying of the expansive clays. Eliminating the risk of movement and distress
is generally not feasible, but it may be possible to further reduce the risk of movement if
significantly more expensive measures are used during construction. It is imperative the
recommendations described in section 4.2.7 Grading and Drainage of this report be followed to
reduce movement.
4.1.2 Sandstone Bedrock
Hard to very hard sandstone bedrock was encountered in all of the borings completed as part of
our study at this site.
The upper portions of the sandstone bedrock below this site can typically be excavated with large
excavation equipment fitted with rock teeth using concentrated effort or ripped with large
bulldozers. Very hard or cemented layers of the bedrock below this site could require breaking
with pneumatic rock breakers.
If the new building foundations are supported partially on soil and partially on sandstone bedrock,
we recommend over-excavation to a depth of 2 feet below the design bearing level where bedrock
is present below foundations. The over-excavation should also extend laterally a sufficient distance
to provide room for installation of a bond break with the sides of the foundation excavation. The
over-excavation into the bedrock should be backfilled with moisture conditioned, properly
compacted on-site soils or imported fill materials. The purpose of the over-excavation is to reduce
differential movement due to differing bearing materials.
4.1.3 Preliminary Foundation Recommendations
The proposed structures may be supported on shallow foundation systems bearing on properly
prepared subgrade soils, imported engineered fill, and/or sandstone bedrock. We recommend a
slab-on-grade for the interior floor system of the proposed buildings. If post tensioned slabs are
chosen as the preferred foundations system, the foundation will function as the floor slab. 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
Preliminary Geotechnical Engineering Report
Goldelm at Fossil Creek ■ Fort Collins, Colorado
April 14, 2015 ■ Terracon Project No. 20155011
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should be used.
4.2 Earthwork
The following presents preliminary recommendations for site preparation, excavation, subgrade
preparation and placement of engineered fills on the project. All earthwork on the project should
be observed and evaluated by Terracon on a full-time basis. The evaluation of earthwork should
include observation of over-excavation operations, testing of engineered fills, subgrade
preparation, subgrade stabilization, and other geotechnical conditions exposed during the
construction of the project.
4.2.1 Site Preparation
Prior to placing any fill, strip and remove existing vegetation and any other deleterious materials
from the proposed construction areas.
Stripped organic materials should be wasted from the site or used to re-vegetate landscaped areas
or exposed slopes after completion of grading operations. Prior to the placement of fills, the site
should be graded to create a relatively level surface to receive fill, and to provide for a relatively
uniform thickness of fill beneath proposed structures.
If fill is placed in areas of the site where existing slopes are steeper than 5:1 (horizontal:vertical),
the area should be benched to reduce the potential for slippage between existing slopes and fills.
Benches should be wide enough to accommodate compaction and earth moving equipment, and
to allow placement of horizontal lifts of fill.
4.2.2 Excavation
It is anticipated that excavations for the proposed construction can be accomplished with
conventional earthmoving equipment. Excavations into the on-site soils may encounter weak
and/or saturated soil conditions with possible caving conditions.
Excavation 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.
The soils to be excavated can vary significantly across the site as their classifications are based
solely on the materials encountered in widely-spaced exploratory test borings. The contractor
should verify that similar conditions exist throughout the proposed area of excavation. If different
subsurface conditions are encountered at the time of construction, the actual conditions should be
evaluated to determine any excavation modifications necessary to maintain safe conditions.
Although evidence of fills or underground facilities such as septic tanks, vaults, basements, and
utilities was not observed during the site reconnaissance, such features could be encountered
Preliminary Geotechnical Engineering Report
Goldelm at Fossil Creek ■ Fort Collins, Colorado
April 14, 2015 ■ Terracon Project No. 20155011
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during construction. If unexpected fills or underground facilities are encountered, such features
should be removed and the excavation thoroughly cleaned prior to backfill placement and/or
construction.
Any over-excavation that extends below the bottom of foundation elevation should extend laterally
beyond all edges of the foundation at least 8 inches per foot of over-excavation depth below the
foundation base elevation. The over-excavation should be backfilled to the foundation base
elevation in accordance with the recommendations presented in this report.
Depending upon depth of excavation and seasonal conditions, surface water infiltration and/or
groundwater may be encountered in excavations on the site. It is anticipated that pumping from
sumps may be utilized to control water within excavations.
The subgrade soil conditions should be evaluated during the excavation process and the stability
of the soils determined at that time by the contractors’ Competent Person. Slope inclinations flatter
than the OSHA maximum values may have to be used. The individual contractor(s) should be
made responsible for designing and constructing stable, temporary excavations as required to
maintain stability of both the excavation sides and bottom. All excavations should be sloped or
shored in the interest of safety following local, and federal regulations, including current OSHA
excavation and trench safety standards. 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
4.2.3 Subgrade Preparation
After the deleterious materials have been removed from the construction areas, the top 8 inches
of the exposed ground surface should be scarified, moisture conditioned, and recompacted to at
least 95 percent of the maximum dry unit weight as determined by ASTM D698 before any new
fill, foundation, or pavement is placed.
If pockets of soft, loose, or otherwise unsuitable materials are encountered at the bottom of the
foundation excavations and it is inconvenient to lower the foundations, the proposed foundation
elevations may be reestablished by over-excavating the unsuitable soils and backfilling with
compacted engineered fill.
After the bottom of the excavation has been compacted, engineered fill can be placed to bring the
building pads and pavement subgrade to the desired grade. Engineered fill should be placed in
accordance with the recommendations presented in subsequent sections of this report.
Preliminary Geotechnical Engineering Report
Goldelm at Fossil Creek ■ Fort Collins, Colorado
April 14, 2015 ■ Terracon Project No. 20155011
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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.
4.2.4 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 pads and pavement subgrade. It should be
noted that on-site soils will require reworking to adjust the moisture content to meet the
compaction criteria.
CDOT Class 1 structure backfill should meet the following material property requirements:
Gradation Percent finer by weight (ASTM C136)
2” 100
No. 4 Sieve 30-100
No.50 Sieve 10-60
No. 200 Sieve 5-20
Soil Properties Value
Liquid Limit 35 (max.)
Plastic Limit 6 (max.)
Imported soils (if required) should meet the following material property requirements:
Gradation Percent finer by weight (ASTM C136)
4” 100
3” 70-100
No. 4 Sieve 50-100
No. 200 Sieve 15-50
Preliminary Geotechnical Engineering Report
Goldelm at Fossil Creek ■ Fort Collins, Colorado
April 14, 2015 ■ Terracon Project No. 20155011
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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 eight feet. Fills on the order of eight feet in depth, when placed and compacted
as recommended in this report, will experience some settlement, generally one 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.
4.2.5 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.
Preliminary Geotechnical Engineering Report
Goldelm at Fossil Creek ■ Fort Collins, Colorado
April 14, 2015 ■ Terracon Project No. 20155011
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4.2.6 Utility Trench Backfill
All trench excavations should be made with sufficient working space to permit construction including
backfill placement and compaction.
All underground piping within or near the proposed structures should be designed with flexible
couplings, so minor deviations in alignment do not result in breakage or distress. Utility knockouts
in foundation walls should be oversized to accommodate differential movements. It is imperative
that utility trenches be properly backfilled with relatively clean materials. If utility trenches are
backfilled with relatively clean granular material, they should be capped with at least 18 inches of
cohesive fill in non-pavement areas to reduce the infiltration and conveyance of surface water
through the trench backfill.
Utility trenches are a common source of water infiltration and migration. All utility trenches that
penetrate beneath the buildings should be effectively sealed to restrict water intrusion and flow
through the trenches that could migrate below the buildings. We recommend constructing an
effective clay “trench plug” that extends at least 5 feet out from the face of the building exteriors.
The plug material should consist of clay compacted at a water content at or above the soil’s optimum
water content. The clay fill should be placed to completely surround the utility line and be compacted
in accordance with recommendations in this report.
It is strongly recommended that a representative of Terracon provide full-time observation and
compaction testing of trench backfill within building and pavement areas.
4.2.7 Grading and Drainage
All grades must be adjusted to provide effective drainage away from the proposed structures
during construction and maintained throughout the life of the proposed project. Infiltration of water
into foundation excavations must be prevented during construction. Landscape irrigation adjacent
to foundations should be minimized or eliminated. Water permitted to pond near or adjacent to
the perimeter of the structures (either during or post-construction) can result in significantly higher
soil movements than those discussed in this report. As a result, any estimations of potential
movement described in this report cannot be relied upon if positive drainage is not obtained and
maintained, and water is allowed to infiltrate the fill and/or subgrade.
Exposed ground (if any) should be sloped at a minimum of 10 percent grade for at least 10 feet
beyond the perimeter of the proposed structures, 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 structures. Backfill against foundations and exterior walls should be properly compacted
and free of all construction debris to reduce the possibility of moisture infiltration. After
construction of the proposed structures and prior to project completion, we recommend
verification of final grading be performed to document positive drainage, as described above, has
been achieved.
Preliminary Geotechnical Engineering Report
Goldelm at Fossil Creek ■ Fort Collins, Colorado
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Flatwork and pavements will be subject to post-construction movement. Maximum grades
practical should be used for paving and flatwork to prevent areas where water can pond. In
addition, allowances in final grades should take into consideration post-construction movement
of flatwork, particularly if such movement would be critical. Where paving or flatwork abuts the
structures, care should be taken that joints are properly sealed and maintained to prevent the
infiltration of surface water.
Planters located adjacent to structures should preferably be self-contained. Sprinkler mains and
spray heads should be located a minimum of 5 feet away from the building line(s). Low-volume,
drip style landscaped irrigation should not be used near the building. Roof drains should
discharge on to pavements or be extended away from the structures a minimum of 10 feet through
the use of splash blocks or downspout extensions. A preferred alternative is to have the roof
drains discharge by solid pipe to storm sewers or to a detention pond or other appropriate outfall.
4.2.8 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.
4.2.9 Corrosion Protection
Results of water-soluble sulfate testing indicate that ASTM Type I or II portland cement should be
specified for all project concrete on and below grade. Foundation concrete should be designed
for low sulfate exposure in accordance with the provisions of the ACI Design Manual, Section
318, Chapter 4.
4.3 Preliminary Foundation Recommendations
The proposed buildings can be supported by shallow foundation systems bearing on properly
prepared on-site soils, imported engineered fill, and/or sandstone bedrock. Preliminary design
recommendations for foundations for the proposed structure and related structural elements are
presented in the following paragraphs.
4.3.1 Post-Tensioned Slabs – Preliminary Design Recommendations
Based on the soil conditions encountered, use of post-tensioned slabs is feasible for support of
the structures provided some foundation movement can be tolerated and:
The post-tensioned slab foundations are properly designed and constructed.
Preliminary Geotechnical Engineering Report
Goldelm at Fossil Creek ■ Fort Collins, Colorado
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Approved materials supporting the foundation are properly placed and compacted.
Proper surface drainage is maintained throughout the life of the structures.
Prudent landscaping measures are used.
Provided foundations are properly designed, foundation movements could result in periodic, and
possibly seasonal, cosmetic distress to drywall, window frames, door frames and other features.
We would anticipate that the frequency of distress and amount of movement would generally
diminish with time provided proper drainage is established and/or maintained.
Based on the subsurface conditions encountered during our preliminary study, we estimate a
maximum allowable net bearing pressure in the range of 1,000 to 3,000 psf may be used for the
design of post-tensioned slabs.
4.3.3 Spread Footings – Preliminary Design Recommendations
Description Value
Bearing material
Properly prepared on-site soil, new, properly placed
engineered fill, and/or sandstone bedrock.
Maximum allowable bearing pressure 1 1,000 to 3,000 psf
Minimum embedment depth below finished
grade 3
30 inches
Estimated differential movement 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. 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.
4.4 Seismic Considerations
Code Used Site Classification
2012 International Building Code (IBC) 1 D 2
1. In general accordance with the 2012 International Building Code, Table 1613.5.2.
2. The 2012 International Building Code (IBC) requires a site soil profile determination extending a
depth of 100 feet for seismic site classification. The current scope requested does not include the
required 100 foot soil profile determination. The borings completed for this project extended to a
maximum depth of about 25 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.
Preliminary Geotechnical Engineering Report
Goldelm at Fossil Creek ■ Fort Collins, Colorado
April 14, 2015 ■ Terracon Project No. 20155011
Responsive ■ Resourceful ■ Reliable 12
4.5 Floor Systems
A slab-on-grade may be utilized for the interior floor system for the proposed buildings provided
some movement can be tolerated. If the very little movement can be tolerated, a structurally-
supported floor system, supported independent of the subgrade materials, is recommended. If
post tensioned slabs are chosen as the foundation system, the foundation system will function as
the floor slab.
4.5.1 Floor System - Preliminary 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. 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 prepared as presented in the 4.2 Earthwork section of
this report.
For preliminary 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-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.
4.6 Swimming Pool - Preliminary Recommendations
We understand a swimming pool is conceptually planned near the clubhouse in the southeastern
portion of the project site.
Although groundwater was not encountered in our exploratory borings completed at this site, it is
possible that groundwater could accumulate on top of the bedrock surface below this site.
Considering the sandstone bedrock was encountered at a depth of about 7 to 15 feet below
existing site grades in the borings completed nearest the proposed swimming pool, it is likely the
swimming pool excavation will penetrate the bedrock surface. If groundwater does accumulate
on top of the bedrock surface, groundwater could affect the proposed swimming pool. If
groundwater levels rise above the bottom of the pool when the pool is empty, uplift loads could
be imposed on the pool bottom slab and hydrostatic pressure could be imposed on the pool walls,
which could cause heaving, cracking, or other damage to the pool bottom slab and walls. The
pool designs should include pressure relief valves that will allow backflow of groundwater into the
empty pool in order to help reduce the potential for hydrostatic loading and subsequent heaving,
cracking, or other damage. A drainage system should be provided around and beneath the pool.
4.7 Preliminary 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,
Preliminary Geotechnical Engineering Report
Goldelm at Fossil Creek ■ Fort Collins, Colorado
April 14, 2015 ■ Terracon Project No. 20155011
Responsive ■ Resourceful ■ Reliable 13
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 – Preliminary 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). If some pavements will be city-maintained, the design of the pavements must use
Larimer County Urban Area Streets Standards (LCUASS).
We assumed the following design parameters for NAPA flexible pavement thickness design:
Automobile Parking Areas
Class I - Parking stalls and parking lots for cars and pick-up trucks, with
Equivalent Single Axle Load (ESAL) up to 7,000 over 20 years
Main Traffic Corridors
Class II – Parking lots with a maximum of 10 trucks per day with Equivalent
Single Axle Load (ESAL) up to 27,000 over 20 years (Including trash trucks)
Subgrade Soil Characteristics
USCS Classification – CL, classified by NAPA as poor
We assumed the following design parameters for ACI rigid pavement thickness design based
upon the average daily truck traffic (ADTT):
Automobile Parking Areas
ACI Category A: Automobile parking with an ADTT of 1 over 20 years
Main Traffic Corridors
ACI Category A: Automobile parking area and service lanes with an ADTT of
up to 10 over 20 years
Subgrade Soil Characteristics
USCS Classification – CL
Concrete modulus of rupture value of 600 psi
We should be contacted to confirm and/or modify the recommendations contained herein if actual
traffic volumes differ from the assumed values shown above.
Preliminary Geotechnical Engineering Report
Goldelm at Fossil Creek ■ Fort Collins, Colorado
April 14, 2015 ■ Terracon Project No. 20155011
Responsive ■ Resourceful ■ Reliable 14
Recommended preliminary 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 3 6 -- 9
B -- -- 5½ 5½
Service Lanes
(NAPA Class II and ACI Category A)
A 4½ 6 -- 10½
B -- -- 6 6
Aggregate base course (if used on the site) should consist of a blend of sand and gravel which
meets strict specifications for quality and gradation. Use of materials meeting Colorado
Department of Transportation (CDOT) Class 5 or 6 specifications is recommended for aggregate
base course. Aggregate base course should be placed in lifts not exceeding 6 inches and
compacted to a minimum of 95 percent of the maximum dry unit weight as determined by ASTM
D698.
Asphaltic concrete should be composed of a mixture of aggregate, filler and additives (if required)
and approved bituminous material. The asphalt concrete should conform to approved mix
designs stating the Superpave properties, optimum asphalt content, job mix formula and
recommended mixing and placing temperatures. Aggregate used in asphalt concrete should
meet particular gradations. Material meeting CDOT Grading S 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
Preliminary Geotechnical Engineering Report
Goldelm at Fossil Creek ■ Fort Collins, Colorado
April 14, 2015 ■ Terracon Project No. 20155011
Responsive ■ Resourceful ■ Reliable 15
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.
Although not required for structural support, a minimum 4-inch thick aggregate base course layer
is recommended for the PCC pavements to help reduce the potential for slab curl, shrinkage
cracking, and subgrade “pumping” through joints. Proper joint spacing will also be required for
PCC pavements to prevent excessive slab curling and shrinkage cracking. All joints should be
sealed to prevent entry of foreign material and dowelled where necessary for load transfer.
For areas subject to concentrated and repetitive loading conditions (if any) such as dumpster
pads, truck delivery docks and ingress/egress aprons, we recommend using a portland cement
concrete pavement with a thickness of at least 6 inches underlain by at least 4 inches of granular
base. Prior to placement of the granular base, the areas should be thoroughly proofrolled. For
dumpster pads, the concrete pavement area should be large enough to support the container and
tipping axle of the refuse truck.
Pavement performance is affected by its surroundings. In addition to providing preventive
maintenance, the civil engineer should consider the following recommendations in the design and
layout of pavements:
Site grades should slope a minimum of 2 percent away from the pavements;
The subgrade and the pavement surface have a minimum 2 percent slope to promote proper
surface drainage;
Consider appropriate edge drainage and pavement under drain systems;
Install pavement drainage surrounding areas anticipated for frequent wetting;
Install joint sealant and seal cracks immediately;
Seal all landscaped areas in, or adjacent to pavements to reduce moisture migration to
subgrade soils; and
Placing compacted, low permeability backfill against the exterior side of curb and gutter.
4.7.3 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
Preliminary Geotechnical Engineering Report
Goldelm at Fossil Creek ■ Fort Collins, Colorado
April 14, 2015 ■ Terracon Project No. 20155011
Responsive ■ Resourceful ■ Reliable 16
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’s Scope of Services has been provided under the belief that this site will be used as
apartments. As such, Terracon would like to inform the Client that if this apartment project is
converted at any time to another purpose such as condominiums, the Client understands the
services Terracon is providing is not applicable for a condominium project and that a separate
consultant will need to be retained for such services. Terracon will have no liability for any such
unintended use of our services and Client agrees to defend, indemnify, and hold harmless
Terracon for any such unintended usage.
Terracon should be retained to review the final design plans and specifications so comments can
be made regarding interpretation and implementation of our geotechnical recommendations in
the design and specifications. Terracon also should be retained to provide observation and testing
services during grading, excavation, foundation construction and other earth-related construction
phases of the project.
The analysis and recommendations presented in this report are based upon the data obtained
from the borings performed at the indicated locations and from other information discussed in this
report. This report does not reflect variations that may occur between borings, across the site, or
due to the modifying effects of construction or weather. The nature and extent of such variations
may not become evident until during or after construction. If variations appear, we should be
immediately notified so that further evaluation and supplemental recommendations can be
provided.
The scope of services for this project does not include either specifically or by implication any
environmental or biological (e.g., mold, fungi, and bacteria) assessment of the site or identification
or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about
the potential for such contamination or pollution, other studies should be undertaken.
This report has been prepared for the exclusive use of our client for specific application to the
project discussed and has been prepared in accordance with generally accepted geotechnical
engineering practices. No warranties, either express or implied, are intended or made. Site
safety, excavation support, and dewatering requirements are the responsibility of others. In the
event that changes in the nature, design, or location of the project as described in this report are
planned, the conclusions and recommendations contained in this report shall not be considered
valid unless Terracon reviews the changes and either verifies or modifies the conclusions of this
report in writing.
APPENDIX A
FIELD EXPLORATION
SITE LOCATION MAP
TOPOGRAPHIC MAP IMAGE COURTESY OF THE U.S. GEOLOGICAL SURVEY
QUADRANGLES INCLUDE: FORT COLLINS, CO (1/1/1984) and LOVELAND, CO (1/1/1984).
1901 Sharp Point Dr Suite C
Ft. Collins, CO 80525
20155011
Project Manager:
Drawn by:
Checked by:
Approved by:
BCR
EDB
EDB
1:24,000
Goldelm at Fossil Creek
Northwest of South College Avenue and Crestridge Drive
3/19/2015 Fort Collins, CO
Project No.
Scale:
File Name:
Date: A-1
EDB Exhibit
0’ 60’ 120’
APPROXIMATE SCALE
Scale:
EDB
EDB
BCR
EDB
Project Manager:
Drawn by:
Checked by:
Approved by:
EXPLORATION PLAN
Goldelm at Fossil Creek
Northwest of South College Avenue and Crestridge Drive
Fort Collins, Colorado
1
20155011 Figure
3/23/2015
1=120’
Project No.
File Name:
Date:
DIAGRAM IS FOR GENERAL LOCATION ONLY, AND
IS NOT INTENDED FOR CONSTRUCTION PURPOSES
2 Approximate Location of Preliminary
Borings
LEGEND
1
2
3
7
6
4
5
Approximate Location of
Temporary Benchmark (Survey
Marker Labeled Control Point
RR – Interpolated Elevation
5007.2’)
1901 Sharp Point Drive, Suite C Fort Collins, Colorado 80525
PH. (970) 484-0359 FAX. (970) 484-0454
Geotechnical Engineering Report
Goldelm at Fossil Creek ■ Fort Collins, Colorado
April 14, 2015 ■ Terracon Project No. 20155011
Responsive ■ Resourceful ■ Reliable Exhibit A-3
Field Exploration Description
The locations of borings were based upon the proposed development shown on the provided site
plan. The borings were located in the field by measuring from existing site features. The ground
surface elevation was surveyed at each boring location referencing the temporary benchmark
shown on Exhibit A-2 using an engineer’s level.
The borings were drilled with a CME-75 truck-mounted rotary drill rig with solid-stem augers.
During the drilling operations, lithologic logs of the borings were recorded by the field engineer.
Disturbed samples were obtained at selected intervals utilizing a 2-inch outside diameter split-
spoon sampler and a 3-inch outside diameter ring-barrel sampler. Penetration resistance values
were recorded in a manner similar to the standard penetration test (SPT). This test consists of
driving the sampler into the ground with a 140-pound hammer free-falling through a distance of
30 inches. The number of blows required to advance the ring-barrel sampler 12 inches (18 inches
for standard split-spoon samplers, final 12 inches are recorded) or the interval indicated, is
recorded as a standard penetration resistance value (N-value). The blow count values are
indicated on the boring logs at the respective sample depths. Ring-barrel sample blow counts are
not considered N-values.
A CME automatic SPT hammer was used to advance the samplers in the borings performed on this
site. A greater efficiency is typically achieved with the automatic hammer compared to the
conventional safety hammer operated with a cathead and rope. Published correlations between the
SPT values and soil properties are based on the lower efficiency cathead and rope method. This
higher efficiency affects the standard penetration resistance blow count value by increasing the
penetration per hammer blow over what would be obtained using the cathead and rope method. The
effect of the automatic hammer's efficiency has been considered in the interpretation and analysis of
the subsurface information for this report.
The standard penetration test provides a reasonable indication of the in-place density of sandy
type materials, but only provides an indication of the relative stiffness of cohesive materials since
the blow count in these soils may be affected by the moisture content of the soil. In addition,
considerable care should be exercised in interpreting the N-values in gravelly soils, particularly
where the size of the gravel particle exceeds the inside diameter of the sampler.
Groundwater measurements were obtained in the borings at the time of site exploration. After
completion of drilling, the borings were backfilled with auger cuttings. Some settlement of the
backfill may occur and should be repaired as soon as possible.
0.5
15.0
24.4
TOPSOIL - 6 inches
LEAN CLAY WITH SAND (CL), trace
calcareous nodules, brown, stiff to very stiff
SEDIMENTARY BEDROCK - SANDSTONE,
fine grained, brown and olive, very hard
A highly cemented lense was encountered from
a depth of approximately 15 to 17 feet below the
ground surface.
Boring Terminated at 24.4 Feet
8-12
6-5-6
N=11
4-4-6
N=10
7-10
50/6"
N=50/6"
50/5"
N=50/5"
0.065
10 78
10
9
9
14
11
102
122
32-15-17
4982
4967.5
4958.5
-2.9
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
LOCATION
DEPTH
Latitude: 40.509115° Longitude: -105.078349°
GRAPHIC LOG
See Exhibit A-2
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20155011.GPJ TERRACON2012.GDT 3/23/15
NW of S College Ave and Crestridge Dr
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
4 inch solid-stem augers
Abandonment Method:
Borings backfilled with soil cuttings upon completion.
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
Notes:
Project No.: 20155011
Drill Rig: CME-75
Boring Started: 3/4/2015
BORING LOG NO. 1
CLIENT: GOLDELM Apartments
Lakeside, MT
0.5
7.0
19.3
TOPSOIL - 6 inches
SILTY SAND (SM), fine grained, brown to light
brown, loose to medium dense
SEDIMENTARY BEDROCK - SANDSTONE,
fine grained, brown and olive, very hard
A highly cemented lense was encountered from
a depth of approximately 13 to 16 feet below the
ground surface.
Boring Terminated at 19.3 Feet
6-9
5-5-5
N=10
50/3"
N=50/3"
50/3"
N=50/3"
7 42
7
9
10
87 NP
4980
4973.5
4961
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
LOCATION
DEPTH
Latitude: 40.508383° Longitude: -105.079042°
GRAPHIC LOG
See Exhibit A-2
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20155011.GPJ TERRACON2012.GDT 3/23/15
NW of S College Ave and Crestridge Dr
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
4 inch solid-stem augers
Abandonment Method:
Borings backfilled with soil cuttings upon completion.
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
Notes:
Project No.: 20155011
Drill Rig: CME-75
Boring Started: 3/4/2015
BORING LOG NO. 2
CLIENT: GOLDELM Apartments
Lakeside, MT
Driller: Drilling Engineers, Inc.
Boring Completed: 3/4/2015
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.
0.5
4.5
19.2
TOPSOIL - 6 inches
SILTY SAND, fine grained, brown, loose to
medium dense
SEDIMENTARY BEDROCK - SANDSTONE,
fine grained, brown to gray, very hard
Boring Terminated at 19.2 Feet
5-7
13-33-50
N=83
50/6"
N=50/6"
50/3"
N=50/3"
50/2"
N=50/2"
6
7
11
10
11
86
4994.5
4990.5
4975.5
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
LOCATION
DEPTH
Latitude: 40.507952° Longitude: -105.079821°
GRAPHIC LOG
See Exhibit A-2
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20155011.GPJ TERRACON2012.GDT 3/23/15
NW of S College Ave and Crestridge Dr
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
4 inch solid-stem augers
Abandonment Method:
Borings backfilled with soil cuttings upon completion.
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
Notes:
Project No.: 20155011
Drill Rig: CME-75
Boring Started: 3/4/2015
BORING LOG NO. 3
CLIENT: GOLDELM Apartments
Lakeside, MT
Driller: Drilling Engineers, Inc.
Boring Completed: 3/4/2015
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.
0.5
19.0
24.3
TOPSOIL - 6 inches
SILTY SAND WITH GRAVEL (SM), fine
grained, brown, loose to medium dense
SEDIMENTARY BEDROCK - SANDSTONE,
fine grained, brown and olive, very hard
A highly cemented lense was encountered from
a depth of approximately 19 to 20 feet below the
ground surface.
Boring Terminated at 24.3 Feet
3-5
2-3-3
N=6
3-6-15
N=21
7-5-6
N=11
50/2"
N=50/2"
50/3"
N=50/3"
0.001
16
6
6
7
9
5
13
72
NP
4977.5
4959
4954
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
LOCATION
DEPTH
Latitude: 40.508491° Longitude: -105.080592°
GRAPHIC LOG
See Exhibit A-2
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20155011.GPJ TERRACON2012.GDT 3/23/15
NW of S College Ave and Crestridge Dr
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
4 inch solid-stem augers
Abandonment Method:
Borings backfilled with soil cuttings upon completion.
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
Notes:
Project No.: 20155011
Drill Rig: CME-75
Boring Started: 3/4/2015
BORING LOG NO. 4
CLIENT: GOLDELM Apartments
Lakeside, MT
0.5
2.0
19.3
TOPSOIL - 6 inches
SILTY SAND, fine grained, brown to light
brown
SEDIMENTARY BEDROCK - SANDSTONE,
fine grained, brown, very hard
Boring Terminated at 19.3 Feet
50/3"
N=50/3"
50/2"
N=50/2"
50/4"
N=50/4"
50/3"
N=50/3"
50/4"
N=50/4"
17
11
10
11
12
69
4981
4979.5
4962
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
LOCATION
DEPTH
Latitude: 40.508459° Longitude: -105.082096°
GRAPHIC LOG
See Exhibit A-2
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20155011.GPJ TERRACON2012.GDT 3/23/15
NW of S College Ave and Crestridge Dr
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
4 inch solid-stem augers
Abandonment Method:
Borings backfilled with soil cuttings upon completion.
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
Notes:
Project No.: 20155011
Drill Rig: CME-75
Boring Started: 3/4/2015
BORING LOG NO. 5
CLIENT: GOLDELM Apartments
Lakeside, MT
Driller: Drilling Engineers, Inc.
Boring Completed: 3/4/2015
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
0.5
1.0
19.3
TOPSOIL - 6 inches
SILTY SAND, fine grained, brown
SEDIMENTARY BEDROCK - SANDSTONE,
fine grained, brown, very hard
A highly cemented lense was encountered from
a depth of approximately 14 to 16 feet below the
ground surface.
Boring Terminated at 19.3 Feet
50/6"
N=50/6"
50/6"
N=50/6"
50/3"
N=50/3"
50/0"
N=50/0"
50/3"
N=50/3"
0.004 11
17
4996.5
4996
4977.5
0
0
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
LOCATION
DEPTH
Latitude: 40.50743° Longitude: -105.08272°
GRAPHIC LOG
See Exhibit A-2
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20155011.GPJ TERRACON2012.GDT 3/23/15
NW of S College Ave and Crestridge Dr
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
4 inch solid-stem augers
Abandonment Method:
Borings backfilled with soil cuttings upon completion.
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
Notes:
Project No.: 20155011
Drill Rig: CME-75
Boring Started: 3/4/2015
BORING LOG NO. 6
CLIENT: GOLDELM Apartments
Lakeside, MT
Driller: Drilling Engineers, Inc.
Boring Completed: 3/4/2015
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
0.5
14.2
TOPSOIL - 6 inches
SEDIMENTARY BEDROCK - SANDSTONE,
fine grained, brown to gray, very hard
A highly cemented lense was encountered from
a depth of approximately 4 to 6 feet below the
ground surface.
A highly cemented lense was encountered from
a depth of approximately 12 to 13 feet below the
ground surface.
Boring Terminated at 14.2 Feet
50/3"
N=50/3"
50/3"
N=50/3"
50/3"
N=50/3"
50/2"
N=50/2"
5
11
13
5003.5
4989.5
1
0
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
LOCATION
DEPTH
Latitude: 40.507252° Longitude: -105.081498°
GRAPHIC LOG
See Exhibit A-2
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20155011.GPJ TERRACON2012.GDT 3/23/15
NW of S College Ave and Crestridge Dr
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
4 inch solid-stem augers
Abandonment Method:
Borings backfilled with soil cuttings upon completion.
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
Notes:
Project No.: 20155011
Drill Rig: CME-75
Boring Started: 3/4/2015
BORING LOG NO. 7
CLIENT: GOLDELM Apartments
Lakeside, MT
Driller: Drilling Engineers, Inc.
Boring Completed: 3/4/2015
Exhibit: A-10
See Exhibit A-3 for description of field
procedures.
See Appendix B for description of laboratory
procedures and additional data (if any).
See Appendix C for explanation of symbols and
abbreviations.
APPENDIX B
LABORATORY TESTING
Geotechnical Engineering Report
Goldelm at Fossil Creek ■ Fort Collins, Colorado
April 14, 2015 ■ Terracon Project No. 20155011
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 preliminary foundation and earthwork
recommendations. The laboratory tests were performed in general accordance with applicable
locally accepted standards. Soil samples were classified in general accordance with the Unified
Soil Classification System described in Appendix C. Rock samples were visually classified in
general accordance with the description of rock properties presented in Appendix C. Procedural
standards noted in this report are for reference to methodology in general. In some cases variations
to methods are applied as a result of local practice or professional judgment.
Water content Plasticity index
Grain-size distribution
Consolidation/swell
Dry density
Water-soluble sulfate content
0
10
20
30
40
50
60
0 20 40 60 80 100
CL or OL CH or OH
ML or OL
MH or OH
Boring ID Depth PL PI Description
LEAN CLAY with SAND
SILTY SAND
SILTY SAND with GRAVEL
CL
SM
SM
Fines
P
L
A
S
T
I
C
I
T
Y
I
N
D
E
X
LIQUID LIMIT
"U" Line
"A" Line
32
NP
NP
15
NP
NP
17
NP
NP
78
42
16
LL USCS
1
2
4
ATTERBERG LIMITS RESULTS
ASTM D4318
2 - 3
2 - 3
9 - 10.5
PROJECT NUMBER: 20155011
PROJECT: Goldelm at Fossil Creek
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 16
20 30
40 50
1.5 6 200
810
78.0
41.7
16.2
0.0
1.5
30.9
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
15
NP
NP
17
NP
NP
D100
Cc Cu
SILT OR CLAY
4
D30 D10 %Gravel %Sand
1
2
4
LEAN CLAY with SAND(CL)
SILTY SAND(SM)
SILTY SAND with GRAVEL(SM)
32
NP
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
100 1,000 10,000
AXIAL STRAIN, %
PRESSURE, psf
SWELL CONSOLIDATION TEST
ASTM D4546
NOTES: Sample exhibited 2.9 percent compression upon wetting under an applied pressure of 500 psf.
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
PROJECT NUMBER: 20155011
PROJECT: Goldelm at Fossil Creek
SITE: NW of S College Ave and
Crestridge Dr
Fort Collins, Colorado
CLIENT: GOLDELM Apartments
Lakeside, MT
EXHIBIT: B-4
Specimen Identification Classification , pcf
1 100 5
WC, %
2 - 3 ft LEAN CLAY with SAND(CL)
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. TC_CONSOL_STRAIN-USCS 20155011.GPJ TERRACON2012.GDT 3/19/15
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
100 1,000 10,000
AXIAL STRAIN, %
PRESSURE, psf
SWELL CONSOLIDATION TEST
ASTM D4546
NOTES: Sample exhibited 1.5 percent compression upon wetting under an applied pressure of 500 psf.
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
PROJECT NUMBER: 20155011
PROJECT: Goldelm at Fossil Creek
SITE: NW of S College Ave and
Crestridge Dr
Fort Collins, Colorado
CLIENT: GOLDELM Apartments
Lakeside, MT
EXHIBIT: B-5
Specimen Identification Classification , pcf
2 92 4
WC, %
2 - 3 ft SILTY SAND(SM)
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. TC_CONSOL_STRAIN-USCS 20155011.GPJ TERRACON2012.GDT 3/19/15
TASK NO: 150310027
Analytical Results
Terracon, Inc. - Fort Collins
Bryce C. Reeves
Company:
Report To:
Company:
Bill To:
1901 Sharp Point Drive
Suite C
Fort Collins CO 80525
Accounts Payable
Terracon, Inc. - Lenexa
13910 W. 96th Terrace
Lenexa KS 66215
Goldelm at Fossil Creek 20155011
Date Reported: 3/17/15
Task No.: 150310027
Matrix: Soil - Geotech
Date Received: 3/10/15
Client Project:
Client PO:
Customer Sample ID Borehole #1 @ 4 Ft.
Test Method
Lab Number: 150310027-01
Result
Sulfate - Water Soluble 0.065 % AASHTO T290-91/ ASTM D4327
Customer Sample ID Borehole #4 @ 4-5.5 Ft.
Test Method
Lab Number: 150310027-02
Result
Sulfate - Water Soluble 0.001 % AASHTO T290-91/ ASTM D4327
Customer Sample ID Borehole #6 @ 4 Ft.
Test Method
Lab Number: 150310027-03
Result
Sulfate - Water Soluble 0.004 % AASHTO T290-91/ ASTM D4327
240 South Main Street / Brighton, CO 80601-0507 / 303-659-2313
Mailing Address: P.O. Box 507 / Brighton, CO 80601-0507 / Fax: 303-659-2315
DATA APPROVED FOR RELEASE BY
Abbreviations/ References:
150310027
AASHTO - American Association of State Highway and Transportation Officials.
ASTM - American Society for Testing and Materials.
ASA - American Society of Agronomy.
DIPRA - Ductile Iron Pipe Research Association Handbook of Ductile Iron Pipe.
xhibit B-6
APPENDIX C
SUPPORTING DOCUMENTS
Exhibit: C-1
Unconfined
Compressive
Strength
Qu, (psf)
500 to 1,000
2,000 to 4,000
> 8,000
less than 500
1,000 to 2,000
4,000 to 8,000
Non-plastic
Low
Medium
High
DESCRIPTION OF SYMBOLS AND ABBREVIATIONS
SAMPLING
WATER LEVEL
FIELD TESTS
GENERAL NOTES
Over 12 in. (300 mm)
12 in. to 3 in. (300mm to 75mm)
3 in. to #4 sieve (75mm to 4.75 mm)
#4 to #200 sieve (4.75mm to 0.075mm
Passing #200 sieve (0.075mm)
Particle Size
< 5
5 - 12
> 12
Percent of
Dry Weight
Descriptive Term(s)
of other constituents
RELATIVE PROPORTIONS OF FINES
0
1 - 10
11 - 30
> 30
Plasticity Index
Soil classification is based on the Unified Soil Classification System. Coarse Grained Soils have more than 50% of their dry
weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand. Fine Grained Soils have
less than 50% of their dry weight retained on a #200 sieve; they are principally described as clays if they are plastic, and
silts if they are slightly plastic or non-plastic. Major constituents may be added as modifiers and minor constituents may be
added according to the relative proportions based on grain size. In addition to gradation, coarse-grained soils are defined
on the basis of their in-place relative density and fine-grained soils on the basis of their consistency.
LOCATION AND ELEVATION NOTES
Percent of
Dry Weight
Major Component
of Sample
Trace
With
Modifier
RELATIVE PROPORTIONS OF SAND AND GRAVEL GRAIN SIZE TERMINOLOGY
Trace
With
Modifier
DESCRIPTIVE SOIL CLASSIFICATION
Boulders
Cobbles
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
Design
Soluble Sulfate
Used to determine the quantitative amount of soluble
sulfates within a soil mass.
Exhibit C-5
REPORT TERMINOLOGY
(Based on ASTM D653)
Allowable Soil
Bearing Capacity
The recommended maximum contact stress developed at the interface of the foundation
element and the supporting material.
Alluvium
Soil, the constituents of which have been transported in suspension by flowing water and
subsequently deposited by sedimentation.
Aggregate Base
Course
A layer of specified material placed on a subgrade or subbase usually beneath slabs or
pavements.
Backfill A specified material placed and compacted in a confined area.
Bedrock
A natural aggregate of mineral grains connected by strong and permanent cohesive forces.
Usually requires drilling, wedging, blasting or other methods of extraordinary force for
excavation.
Bench A horizontal surface in a sloped deposit.
Caisson (Drilled
Pier or Shaft)
A concrete foundation element cast in a circular excavation which may have an enlarged base.
Sometimes referred to as a cast-in-place pier or drilled shaft.
Coefficient of
Friction
A constant proportionality factor relating normal stress and the corresponding shear stress at
which sliding starts between the two surfaces.
Colluvium
Soil, the constituents of which have been deposited chiefly by gravity such as at the foot of a
slope or cliff.
Compaction The densification of a soil by means of mechanical manipulation
Concrete Slab-on-
Grade
A concrete surface layer cast directly upon a base, subbase or subgrade, and typically used
as a floor system.
Differential
Movement
Unequal settlement or heave between, or within foundation elements of structure.
Earth Pressure The pressure exerted by soil on any boundary such as a foundation wall.
ESAL
Equivalent Single Axle Load, a criteria used to convert traffic to a uniform standard, (18,000
pound axle loads).
Engineered Fill
Specified material placed and compacted to specified density and/or moisture conditions
under observations of a representative of a geotechnical engineer.
Equivalent Fluid
A hypothetical fluid having a unit weight such that it will produce a pressure against a lateral
support presumed to be equivalent to that produced by the actual soil. This simplified
approach is valid only when deformation conditions are such that the pressure increases
linearly with depth and the wall friction is neglected.
Existing Fill (or
Man-Made Fill)
Materials deposited throughout the action of man prior to exploration of the site.
Existing Grade The ground surface at the time of field exploration.
Exhibit C-6
REPORT TERMINOLOGY
(Based on ASTM D653)
Expansive Potential The potential of a soil to expand (increase in volume) due to absorption of moisture.
Finished Grade The final grade created as a part of the project.
Footing A portion of the foundation of a structure that transmits loads directly to the soil.
Foundation The lower part of a structure that transmits the loads to the soil or bedrock.
Frost Depth The depth at which the ground becomes frozen during the winter season.
Grade Beam
A foundation element or wall, typically constructed of reinforced concrete, used to span between
other foundation elements such as drilled piers.
Groundwater Subsurface water found in the zone of saturation of soils or within fractures in bedrock.
Heave Upward movement.
Lithologic The characteristics which describe the composition and texture of soil and rock by observation.
Native Grade The naturally occurring ground surface.
Native Soil Naturally occurring on-site soil, sometimes referred to as natural soil.
Optimum Moisture
Content
The water content at which a soil can be compacted to a maximum dry unit weight by a given
compactive effort.
Perched Water
Groundwater, usually of limited area maintained above a normal water elevation by the
presence of an intervening relatively impervious continuous stratum.
Scarify To mechanically loosen soil or break down existing soil structure.
Settlement Downward movement.
Skin Friction (Side
Shear)
The frictional resistance developed between soil and an element of the structure such as a
drilled pier.
Soil (Earth)
Sediments or other unconsolidated accumulations of solid particles produced by the physical
and chemical disintegration of rocks, and which may or may not contain organic matter.
Strain The change in length per unit of length in a given direction.
Stress The force per unit area acting within a soil mass.
Strip To remove from present location.
Subbase A layer of specified material in a pavement system between the subgrade and base course.
Subgrade The soil prepared and compacted to support a structure, slab or pavement system.
Corrosion Potential
Unconfined
Compression
To obtain the approximate compressive strength of soils that
possess sufficient cohesion to permit testing in the
unconfined state.
Bearing Capacity
Analysis for
Foundations
Water Content
Used to determine the quantitative amount of water in a soil
mass.
Index Property Soil
Behavior
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
Modified
Dames &
Moore Ring
Sampler
Standard
Penetration
Test
Unless otherwise noted, Latitude and Longitude are approximately determined using a hand-held GPS device. The accuracy
of such devices is variable. Surface elevation data annotated with +/- indicates that no actual topographical survey was
conducted to confirm the surface elevation. Instead, the surface elevation was approximately determined from topographic
maps of the area.
Standard Penetration Test
Resistance (Blows/Ft.)
Hand Penetrometer
Torvane
Dynamic Cone Penetrometer
Photo-Ionization Detector
Organic Vapor Analyzer
STRENGTH TERMS
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
NP
0.111
0.099
0.339
4.75
12.5
25
1
2
4
GRAIN SIZE IN MILLIMETERS
PERCENT FINER BY WEIGHT
coarse fine
2 - 3
2 - 3
9 - 10.5
3/8 3 100
3 2 140
COBBLES
GRAVEL SAND
USCS Classification
22.0
56.8
52.9
D60
coarse medium
Boring ID Depth
Boring ID Depth
GRAIN SIZE DISTRIBUTION
ASTM D422
2 - 3
2 - 3
9 - 10.5
PROJECT NUMBER: 20155011
PROJECT: Goldelm at Fossil Creek
SITE: NW of S College Ave and Crestridge Dr
Fort Collins, Colorado
CLIENT: GOLDELM Apartments
Lakeside, MT
EXHIBIT: B-3
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GRAIN SIZE: USCS-2 20155011.GPJ TERRACON2012.GDT 3/19/15
SITE: NW of S College Ave and Crestridge Dr
Fort Collins, Colorado
CLIENT: GOLDELM Apartments
Lakeside, MT
EXHIBIT: B-2
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. ATTERBERG LIMITS 20155011.GPJ TERRACON2012.GDT 3/19/15
CL-ML
PROJECT: Goldelm at Fossil Creek
FIELD TEST
RESULTS
SULFATES (%)
PERCENT FINES
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
Surface Elev.: 5003.9 (Ft.)
ELEVATION (Ft.)
SAMPLE TYPE
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
RECOVERY ()
SWELL (%)
No free water observed
WATER LEVEL OBSERVATIONS
abbreviations.
PROJECT: Goldelm at Fossil Creek
FIELD TEST
RESULTS
SULFATES (%)
PERCENT FINES
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
Surface Elev.: 4997.0 (Ft.)
ELEVATION (Ft.)
SAMPLE TYPE
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
15
RECOVERY ()
SWELL (%)
No free water observed
WATER LEVEL OBSERVATIONS
abbreviations.
PROJECT: Goldelm at Fossil Creek
FIELD TEST
RESULTS
SULFATES (%)
PERCENT FINES
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
Surface Elev.: 4981.4 (Ft.)
ELEVATION (Ft.)
SAMPLE TYPE
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
15
RECOVERY ()
SWELL (%)
No free water observed
WATER LEVEL OBSERVATIONS
Driller: Drilling Engineers, Inc.
Boring Completed: 3/4/2015
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: Goldelm at Fossil Creek
FIELD TEST
RESULTS
SULFATES (%)
PERCENT FINES
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
Surface Elev.: 4978.2 (Ft.)
ELEVATION (Ft.)
SAMPLE TYPE
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
15
20
RECOVERY ()
SWELL (%)
No free water observed
WATER LEVEL OBSERVATIONS
PROJECT: Goldelm at Fossil Creek
FIELD TEST
RESULTS
SULFATES (%)
PERCENT FINES
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
Surface Elev.: 4994.8 (Ft.)
ELEVATION (Ft.)
SAMPLE TYPE
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
15
RECOVERY ()
SWELL (%)
No free water observed
WATER LEVEL OBSERVATIONS
PROJECT: Goldelm at Fossil Creek
FIELD TEST
RESULTS
SULFATES (%)
PERCENT FINES
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
Surface Elev.: 4980.3 (Ft.)
ELEVATION (Ft.)
SAMPLE TYPE
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
15
RECOVERY ()
SWELL (%)
No free water observed
WATER LEVEL OBSERVATIONS
Driller: Drilling Engineers, Inc.
Boring Completed: 3/4/2015
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: Goldelm at Fossil Creek
FIELD TEST
RESULTS
SULFATES (%)
PERCENT FINES
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
Surface Elev.: 4982.7 (Ft.)
ELEVATION (Ft.)
SAMPLE TYPE
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
15
20
RECOVERY ()
SWELL (%)
No free water observed
WATER LEVEL OBSERVATIONS