HomeMy WebLinkAboutMULBERRY AND LEMAY CROSSINGS, 2ND FILING, HOME DEPOT - MAJOR AMENDMENT - 36-96I - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORT0-
DIAGRAM IS FOR GENERAL LOCATION ONLY,
AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES
FIGURE 1: SITE VICINITY MAP
PROPOSED HOME DEPOT - NORTH FORT COLLINS
NIE/C OF MULBERRY ST. AND LEMAY AVE.
FORT COLLINS, COLORADO
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Rejxl No. 2
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301 N. Howes Street
Checked By
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Fort Collins, Colorado 80521
File Nem- 20036085-1
Figwe N
-- —-Geotechnical-Frigihed�ing Exploration ----- -.-- -_ - .-___ _._ ....- .__.... lrerracan
Proposed Home Depot Store
N/E/C East Mulberry Street and South Lemay Avenue
Fort Collins, Colorado
Project No. 20035085
in the design and specifications. Terracon also should be retained to provide testing and
observation during excavation, grading, foundation and 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 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, 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 outlined 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.
15
- Ge6teec—f rllcaf Engineering Exploration — _._:_ .. .. - lrerracon _ .-....._
Proposed Home Depot Store
N/E/C East Mulberry Street and South Lemay Avenue
Fort Collins, Colorado
Project No. 20035085
Corrosion Protection
A laboratory test was conducted on the following soil sample for- in -situ resistivity
characteristics, as requested in the Home Depot Geotechnical Engineering Guidelines.
This value, in our opinion is generally representative for the soils encountered on -site
and should be used to determine potential corrosive characteristics of the on -site soils
with respect to contact with the various underground materials which will be used for
project construction.
W.Y�"5ry'-
b Lust BonnjiN�ob
.' t rEII MI W o�...
Dept ,1b t
esistivity+OyH[phM Centimeters',. ,
Lm.n�`'.uRw"f�Ylrv""'NI4ti JM�
1
4
4800
Results of soluble sulfate testing indicate that ASTM Type I Portland cement is suitable
for all concrete on and below grade. However, if there is no, or minimal cost differential,
use of ASTM Type II Portland cement is recommended for additional sulfate resistance
of construction concrete. Foundation concrete should be designed in accordance with
the provisions of the ACI Design Manual, Section 318, Chapter 4.
Surface Drainage
Positive drainage should be. provided during construction and maintained throughout the
life of the proposed project. In areas where sidewalks or paving do not immediately
adjoin the structure, we recommend that protective slopes be provided with a minimum
grade of approximately 5 percent for at least 10 feet from perimeter walls. Backfill
against footings; exterior walls, and in utility and sprinkler line trenches should be well
compacted and free of all construction debris to reduce the possibility of moisture
infiltration.
Downspouts, roof drains or scuppers should discharge into splash blocks or extensions
when the ground surface beneath such features is not protected by exterior slabs or
paving. Sprinkler systems should not be installed within 5 feet of foundation walls.
Landscaped irrigation adjacent to the foundation system should be minimized or
eliminated.
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
14
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Geotechnical Engineering Exploration
Proposed Home Depot Store
N/EIC East Mulberry Street and South Lemay Avenue
Fort Collins, Colorado
Project No. 20035085
The soils to be penetrated by the proposed excavations may vary significantly across
the site. The preliminary soil 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.
As a safety measure, it is recommended that all vehicles and soil piles be kept to a
minimum lateral distance from the crest of the slope equal to no less than the slope
height. The exposed slope face should be protected against the elements.
Additional Design and Construction Considerations
Exterior Slab Design and Construction
Exterior slabs -on -grade, exterior architectural features and utilities founded on or in
backfill may experience some movement due to the volume change of the backfill.
Potential movement could be reduced by:
• minimizing moisture increases in the backfill
• controlling moisture -density during placement of backfill
• using designs which allow vertical movement between the exterior features
and adjoining structural elements
• placing effective control joints on relatively close centers
Underground Utility Systems
All piping should be adequately bedded for proper load distribution. It is suggested that
clean, graded gravel compacted to 75 percent of Relative Density ASTM D4253 be
used as bedding. If utilities are excavated below groundwater, temporary dewatering
will be required during excavation, pipe placement and backfilling operations for proper
construction. Utility trenches should be excavated on safe and stable slopes in
accordance with OSHA regulations as discussed above. Backfill should consist of the
on -site soils or imported material approved by the geotechnical engineer. The pipe
backfill should be compacted to a minimum of 95 percent of Standard Proctor Density
ASTM D698.
13
r
_. .-------
Geotechnical Engineering Exploration
-Proposed Home Depot Store
N/E/C East Mulberry Street and South Lemay Avenue
Fort Collins, Colorado
Project No. 20035085
W2 Subgrade Preparation
irerfacan
Subgrade soils beneath any fill materials, interior and exterior slabs should be scarified,
moisture conditioned and compacted to a minimum depth of 12-inches. The moisture
content and compaction of subgrade soils should be maintained until. slab or pavement -
construction.
Fill Materials and Placement
On -site soils free of debris or deleterious materials or approved imported materials may
be used as fill material and are suitable for use as compacted fill beneath exterior slabs.
Imported soils (if required) should conform to the following:
Gradation
Percent finer by weight
(ASTM C136)
3"..........................................................................................................100
No. 4 Sieve .................. :.....................................................................
30-80
No. 200 Sieve...............................................................................50
(max)
• Liquid Limit.......................................................................30
(max)
• Plasticity Index..................................................................15
(max)
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. It is recommended all fill material to placed on the site be
compacted to at least 95 percent of Standard Proctor Density ASTM D698.
On -site clay soils for backfill or grading purposes should be compacted within a moisture
content range of 1 percent below, to 3 percent above optimum. Imported or on -site
granular soils should be compacted within a moisture range of 3 percent below to 3
percent above optimum unless modified by the project geotechnical engineer.
Excavation and Trench Construction
Excavations into the on -site soils may encounter a variety of conditions. 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.
12
Geotechnical Engineering Exploration - ercacon
Proposed Home Depot Store
N/E/C East Mulberry Street and South Lemay Avenue
Fort Collins, Colorado
Project No. 20035085
Based upon the subsurface conditions determined from the geotechnical exploration,
subgrade soils exposed during construction are anticipated to be relatively stable. For
pavement areas, the 2 foot zone of re -processed material to the specified moisture
tolerances could lend to creating an unstable subgrade. However, the stability of the
subgrade may be affected by precipitation, repetitive construction traffic or other
factors.. Overexcavation of wet zones and replacement with granular materials may be
necessary.
Use of lime, fly ash, kiln dust, cement or geotextiles could also be considered as a
stabilization technique, if swell mitigation is required. Laboratory evaluation is
recommended to determine the effect of chemical stabilization on subgrade soils prior to
construction. Lightweight excavation equipment may be required to reduce subgrade
pumping.
Site Preparation
Strip and remove existing landscaping, fill, debris, and other deleterious materials from
proposed building areas as previously mentioned. All exposed surfaces should be free
of mounds and depressions that could prevent uniform compaction.
The site should be initially graded to create a relatively level surface to receive fill, and to
provide for a relatively uniform thickness of fill beneath proposed building structures.
All exposed areas which will receive fill, once properly cleared and benched where
necessary, should be scarified to a minimum depth of eight inches, conditioned to near
optimum moisture content, and compacted.
Although evidence of underground facilities such as septic tanks, cesspools, or
basements were not observed during site reconnaissance, such features could be
encountered during construction. If existing underground utilities conflict with the
proposed construction, the relocation of these utilities should be addressed during
design stages of the project. 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.
It is anticipated that the majority of the excavations for the proposed construction can be
accomplished with conventional earthmoving equipment.
Geotechnical Engineering Exploration
Proposed Home Depot Store
N/E/C East Mulberry Street and South Lemay Avenue
Fort Collins, Colorado
Project No. 20035085
lrerraron
Where the design includes restrained elements, the following equivalent fluid pressures are
recommended:
• At rest:
Cohesive soil backfill (on -site clay) ......................................... 65 psf/ft
Cohesionless soil backfill (on -site or imported sand)..............55 psf/ft
On -site bedrock materials .......................... not recommended for use
• Coefficient of base friction....................................................0.35
• Adhesion at base of footing.............................................500 psf
The lateral earth pressures herein do not include any factor of safety and are not applicable for
submerged soils/hydrostatic loading. Additional recommendations may be necessary if
submerged conditions are to be included in the design.
Fill against grade beams and retaining walls should be compacted to densities specified in
Earthwork. Compaction of each lift adjacent to walls should be accomplished with hand -
operated tampers or other lightweight compactors. Overcompaction may cause excessive
lateral earth pressures, which could result in wall movement.
Seismic Considerations
The project site is located in Seismic Risk Zone I of the Seismic Zone Map of the United States
as indicated by the 1997 Uniform Building Code. Based upon the nature of the subsurface
materials, a soil profile type Sc should be used for the design of structures for the proposed
project (1997 Uniform Building Code, Table No. 16-J). Liquefaction potential is negligible, and
the need for seismic response spectrum is not necessary.
Earthwork
General Considerations
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. The
evaluation of earthwork should include observation and testing of engineered fill,
subgrade preparation, foundation bearing soils, . and other geotechnical conditions
exposed during the construction of the project.
10
- - ------—--... -.... - - - ._. .
Geotechnical Engineering Explora—tion---------
Proposed Home Depot Store
N/E/C East Mulberry Street and South Lemay Avenue
Fort Collins, Colorado
Project No. 20035085
lferracon
Aggregate base course and select subbase should be placed in lifts not exceeding six inches
and should be compacted to a minimum of 95% Standard Proctor Density (ASTM D698).
Asphalt 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 Hveem and/or Superpave properties, optimum asphalt content, job mix
formula and recommended mixing and placing temperatures. Aggregate used in asphalt
concrete should meet particular gradations meeting Colorado Department of Transportation
Grading S, SX or SG specifications. Mix designs should be submitted prior to construction to
verify their adequacy. Asphalt material should be placed in maximum 3-inch lifts and should be
compacted within a range of 92 to 96% of Maximum Theoretical Density.
Preventative maintenance should be planned and provided for through an on -going pavement
management program in order to enhance future pavement performance. Preventative
maintenance activities are intended to slow the rate of pavement deterioration, and to preserve
the pavement investment.
Preventative maintenance consists of both localized maintenance (e.g. crack 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.
Recommended preventative maintenance policies for asphalt and jointed concrete pavements,
based upon type and severity of distress, are provided. Prior to implementing any
maintenance, additional engineering observation is recommended to determine the type and
extent of preventative maintenance.
Lateral Earth Pressures
For soils above any free water surface, recommended equivalent fluid pressures for
unrestrained foundation elements are:
• Active:
Cohesive soil backfill (on -site clay) ......................................... 50 psf/ft
Cohesionless soil backfill (on -site or imported sand)..............40 psf/ft
Passive:
Cohesive soil backfill (on -site clay).......................................250 psf/ft
Cohesionless soil backfill (on -site or imported sand) ............ 350 psf/ft
9
t -
Geotechriical Engineering Exploration lrerracon
Proposed Home Depot Store
N/E/C East Mulberry Street and South Lemay Avenue
Fort Collins, Colorado
Project No. 20035085
Local drainage characteristics of proposed pavement areas are considered to vary from fair to
good depending upon location on the site. For purposes of this design analysis, fair drainage
characteristics are considered to control the design. These characteristics, coupled with the
approximate duration of saturated subgrade conditions, result in a design drainage coefficient of
1.0 when applying the AASHTO criteria for design.
For flexible pavement design, a terminal serviceability index of 2.0 was utilized along with an
inherent reliability of 70%, and a design life of 10 years. Using an estimated design R-value of
10, appropriate ESAL/day, environmental criteria and other factors, the structural numbers (SN)
of the pavement sections were determined on the basis of the 1993 AASHTO design equation.
In addition to the flexible pavement design analyses, a rigid pavement design analysis was
completed, based upon AASHTO design procedures. Rigid pavement design is based on an
evaluation of the Modulus of Subgrade Reaction of the soils (K-value); the Modulus of Rupture
of the concrete, and other factors previously outlined. The design K-value of 150 for the
subgrade soil was determined by correlation to the laboratory tests results. A modulus of
rupture of 650 psi (working stress 488 psi) was used for pavement concrete. The rigid
pavement thicknesses for each traffic category were determined on the basis of the AASHTO
design equation.
'Z�M,t�t,
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� Recommended
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= A re ate Base
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A
3-1/2
6
9-1/2
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Parking
B
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5-1/2
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9
13
Volume
Main Traffic
B
6
6
Corridors
Each alternative should be investigated with respect to current material availability and
economic conditions. Rigid concrete pavement, a minimum of 6 inches in thickness, is
recommended at the location of dumpsters where trash trucks park and load.
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 base
course. Use of materials meeting Colorado Department of Transportation Class 1
specifications is recommended for select subbase.
Geotechnical Engineering Exploration lferra�ari
!� Proposed Home Depot Store
N/E/C East Mulberry Street and South Lemay Avenue
Fort Collins, Colorado
Project No. 20035085
within the floor slab and relative to the foundation should be limited to 1-inch or less. The
controlled fill procedure will not fully eliminate the possibilities of slab heave; but movements
should be reduced and tend to be more uniform.
For structural design of concrete slabs -on -grade, a modulus of subgrade reaction of 150
pounds per cubic inch (pci) may be used for floors supported on existing fill material and/or
native subsoils.
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 provided in slabs to control the location and extent of
cracking.
• Interior trench backfill placed beneath slabs should be compacted in
accordance with recommended specifications outlined below.
• In areas subjected to normal loading, a minimum 6-inch layer of clean -graded
gravel should be placed beneath . interior slabs. For heavy loading,
reevaluation of slab and/or base course thickness may be required. The
concrete should contain polypropylene fibers. It is recommended a moisture
vapor barrier be installed if moisture sensitive floor coverings are to be used.
• Floor slabs should not be constructed on frozen subgrade.
• Other design and construction considerations, as outlined in the ACI Design
Manual, Section 302.1 R are recommended.
Pavement Design and Construction
Design of pavements for the project have been based on the procedures outlined in the 1993
Guideline for Design of Pavement Structures by the American Association of State Highway
and Transportation Officials (AASHTO). Areas within proposed pavements on the site will be
divided into two categories based upon anticipated traffic and usage.
Traffic criteria provided for pavement thickness designs are to include single 18-kip equivalent
single axle loads (ESAL's) of 50,000 for automobile parking, and 220,000 for heavy volume
and/or fire truck access areas, as provided by the client.
7
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Geotechnical Engineering Exploration
Proposed Home Depot Store
N/E/C East Mulberry Street and South Lemay Avenue
Fort Collins, Colorado
Project No. 20035085
B = Width of footing foundation (ft)
L = Length of footing foundation (ft)
W = Weight of footing + weight of soil directly over the top of the
footing/block (Ibs)
1rerracon
"A unit weight (y) of 120 pcf is recommended for soil (either
undisturbed or compacted backfill) at this site.
The design uplift resistance should be calculated by dividing the ultimate resistance obtained
from the equation above by an appropriate factor of safety. A factor of safety of at least 2 is
recommended for live uplift loads in the analysis. ,
In addition, it is imperative that positive drainage be maintained during construction and
throughout the life of the facility to minimize the potential for surface water infiltration. It is
Terracon's opinion that sub -excavation, if deemed necessary during a foundation excavation
observation, and replacement with controlled fill combined with good positive drainage will
minimize the settlement/expansive potential and will create a more stable bearing stratum.
Exterior footings should be placed a minimum of 30 inches below finished grade for frost
protection and to provide confinement for the bearing soils. Finished grade is the lowest
adjacent grade for perimeter footings.
Footings should be proportioned to reduce differential foundation movement. Proportioning on
the basis of equal total movement is recommended; however, proportioning to relative constant
dead -load pressure will also reduce differential movement between adjacent footings. Total
settlement resulting from the assumed structural loads is estimated to be on the order of 1-inch
or less. Differential settlement is estimated to be on the order of'h-inch within 50-feet and'/<-
inch over the length of the building. 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.
Floor Slab Design and Construction
Some differential movement of a slab -on -grade floor system is possible should the subgrade
soils become elevated in moisture content. To reduce potential slab movements to within the
maximum allowable tolerance allowed by Albertson's, slabs should bear upon a minimum of 3-
feet of moisture controlled over -excavated and replaced material. Depending upon the extent
of overlot grading, over -excavation and replacement of the existing subgrade soils may be
required to achieve the 3-feet depth of controlled fill material. The preparation of the pad should
extend horizontally ten feet beyond the building envelope. The maximum differential movement
0eotechnical Engineering Exploration 1ruraron
Proposed. Home Depot Store
N/E/C East Mulberry Street and South Lemay Avenue
Fort Collins, Colorado
Project No. 20035085
• Conventional -type Spread Footings bearing on undisturbed native subsoils and/or existing
.fill material bearing a minimum of 3-feet above maximum anticipated groundwater levels.
Foundations and masonry walls should be reinforced as necessary to reduce the potential for
distress caused by differential foundation movement. The use of joints at openings or other
discontinuities in masonry walls is recommended.
Foundation excavations and foundation subgrade preparation should be observed by Terracon.
If the soil conditions encountered differ significantly from those presented in this report,
supplemental recommendations will be required.
Slab -on -grade construction is considered acceptable for use, provided that design and
construction recommendations are followed.
Foundation Systems — Conventional Type Spread Footings
Due to the anticipated loads, the type of construction proposed and the soil conditions
encountered, it is recommended the proposed structures be supported using a conventional
type spread footing foundation system founded on undisturbed native subsoils and/or existing
fill material a minimum of 3-feet above the maximum anticipated groundwater levels.
If areas of the fill material are deemed unsuitable during the foundation excavation observation,
the fill material should be overexcavated to a suitable stratum, to be determined at that time,
moisture conditioned at or near optimum moisture content, and replaced in uniform lifts which
are mechanically compacted to at least 95 percent of Standard Proctor Density ASTM D698.
Spread footings bearing uponcontrolled fill material may be designed for a net allowable
bearing pressure of 1,500 psf. In addition, the footings should be sized to maintain a minimum
dead load pressure of 500 psf.
Reinforced concrete foundations, cast in excavations against undisturbed subsoils are
recommended for resistance to uplift for the proposed canopy structure. Footing or dead -man
foundations may be designed using the cone ' method. The equation for determining the
ultimate uplift capacity as a function of footing or dead -man foundation dimension, foundation
depth, and soil weight is presented below:
T„=0.4xy xD2x(B+L)+W
Where: T„= Ultimate uplift capacity (Ibs)
y = Unit weight of soil (Ibs/ft3)"
D = Depth to base of footing foundation below final grade (ft)
5
I
beotec- nical Engineering Exploration
Proposed Home Depot Store
N/E/C East Mulberry Street and South Lemay Avenue
Fort Collins, Colorado
Project No. 20035085
1ferracon
bedrock below was native sands and gravels. Siltstone/claystone was encountered in Test
Boring Nos. 1 through 21 at approximate depths of 17 to 23-feet below existing site grades and
extended to the depths explored, approximately 25-feet. Based on the surface elevations
obtained from the test borings drilled within the building footprint and the approximate depth at
which bedrock was encountered in these borings, we have included, in Appendix A, a bedrock
contour map, Figure No. 3, illustrating the general bedrock contour/profile.
Field and Laboratory Test Results
Field and laboratory test results indicate the native granular soils are medium dense in relative
density and exhibit low expansive potential and moderate bearing capabilities. The existing fill
material exhibits low expansive potential and moderate load bearing capabilities. The
siltstone/claystone bedrock is moderately hard to hard, exhibits moderate to high expansive
potential and moderate to high load bearing characteristics. The in -situ fill material appears
suitable to support the proposed construction, however, a thorough foundation excavation
observation should be performed to verify the competency and consistency of the fill material
prior to any placement of concrete.
Groundwater Conditions
Groundwater was encountered in various borings across the site at approximate depths of 6-1/2
to 10-feet below existing site grades when checked approximately 1 to 2 days after initial drilling
operations. 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.
The estimated piezometric surface was developed for the Home Depot building pad area based
on the groundwater measurement data obtained from the building related test borings. The
groundwater contour map for this portion of the site based on the piezometric data is included
with this report as Figure No. 4. The piezometric surface was estimated using linear
interpolations between test borings and bore hole groundwater measurements at the time of
this study. As illustrated from Figure No. 4, the groundwater flow was estimated to be in the
east to slightly southeast directions.
ENGINEERING RECOMMENDATIONS
Geotechnical Considerations
The site appears suitable for the proposed construction from a geotechnical engineering point
of view. The following foundation system was evaluated for use on the site for the proposed
structures:
.4
I=
Geotechnical Engineering Exploration
Proposed Home Depot Store
N/E/C East Mulberry Street and South Lemay Avenue
Fort Collins, Colorado
Project No. 20035085
Laboratory Testing
lleiracon
All samples retrieved during the field exploration were returned to the laboratory for observation
by the project geotechnical engineer and were classified in accordance with the Unified Soil
Classification System described in Appendix B. Samples of bedrock were classified in
accordance with the general notes for Bedrock Classification. At that time, the field descriptions
were confirmed or modified as necessary and an applicable laboratory -testing program was
formulated to determine engineering properties of the subsurface materials. Boring logs were
prepared and are presented in Appendix A.
Laboratory tests were conducted on selected soil and bedrock samples and are presented in
Appendix B. The test results were used for the geotechnical engineering analyses, and the
development of foundation and earthwork recommendations. All laboratory tests were
performed in general accordance with the applicable ASTM, local or other accepted standards.
Selected soil and bedrock samples were tested for the following engineering properties:
• Water Content
• Dry Density
• Water Soluble Sulfates
• Swell - Consolidation
SITE CONDITIONS
• Compressive Strength
• Plasticity Index
• Expansion
• Grain -Size Distribution
The area for the proposed development is currently a vacant building pad encompassed by
South Lemay Avenue to the west, East Magnolia, Street to the north, 12t' Street to the east and
East Mulberry Street to the south. Two retail buildings, Building I and Building J, and
associated paved parking and drive areas are situated at the southwest portion of the site and a
restaurant building, Building G, is situated at the northwest portion of the site. An existing
detention pond is located at the southeast portion of the site. The site has been elevated
approximately 4 to 7-feet with overlot grading procedures, is relatively flat and sparsely
vegetated with grasses and weeds. North of the site is the existing Wal*Mart Supercenter.
SUBURFACE CONDITIONS
Soil Conditions
Approximately 4-1/2 to 7-1/2 feet of sandy lean clay fill material was encountered at the surface
of each test boring. Underlying the fill material and extending to the depths explored and/or the
3
Geotechnical Engineering Exploration
Proposed Home Depot Store
N/E/C East Mulberry Street and South Lemay Avenue
Fort Collins, Colorado
Project No. 20035085
11•erracan
for the Home Depot Store, given by Home Depot U.S.A., Inc., will be on the order of 5 kips per
linear foot, 120 kips, and 650 pounds per square foot, respectively. Final grading plans were
not provided prior to the subsurface exploration activities, however, it is anticipated the finished
floor elevations of the retail buildings will be at or slightly above existing site grades.
SITE EXPLORATION PROCEDURES
The scope of the services performed for this project included a site reconnaissance by an
engineering geologist, a subsurface exploration program, laboratory testing and engineering
analyses.
Field Exploration
Forty-five test borings were drilled on June 17, 18 and 19, 2003, at the locations shown on the
Boring Location Plan, Figure 1. Twenty-two test borings were located within the footprint of the
proposed Home Depot building and drilled to approximate depths of 25-feet. Three test borings
were located within the footprint of the proposed Building F and were drilled to approximate
depths of 15-feet below existing site grades. Twenty test borings were located within the
proposed parking and drive areas and were drilled to approximate depths of 10-feet below
existing site grades. Test Boring Nos. 25 through 27, P11, P18 through P20 and P22 were not
drilled due to .existing paved parking and/or drive areas and the presence of an existing
detention basin in -place. The borings were advanced with a truck -mounted drilling rig, utilizing
4-inch diameter solid stem augers.
The borings were located in the field with the aid of a hand-held GPS unit. Ground surface
elevations at each boring location were obtained by measurements with an engineer's level
from a temporary bench mark (TBM) as shown on the Boring Location Plan. The accuracy of
boring locations and elevations should only be assumed to the level implied by the methods
used.
Lithologic logs of the borings were recorded by the engineering geologist during the drilling
operations. At selected intervals, samples of the subsurface materials were taken by means of
pushing -thin -walled Shelby -tubes and driving split -spoon and/or ring -barrel samplers.
Penetration resistance measurements were obtained by driving the split -spoon into the
subsurface materials with a 140-pound hammer falling 30 inches., The penetration resistance
value is a useful index in estimating the consistency, relative density or hardness of the
materials encountered.
Groundwater conditions were evaluated in each boring at the time of site exploration and again
on June 19, 2003.
2
GEOTECHNICAL ENGINEERING REPORT
PROPOSED HOME DEPOT STORE
SITE # NW0066
NORTHEAST OF MULBERRY STREET AND SOUTH LEMAY AVENUE
FORT COLLINS, COLORADO
TERRACON PROJECT NO. 20035085
JULY 14, 2003
INTRODUCTION
This report contains the results of our geotechnical engineering exploration for the proposed
Home Depot Store and associated paved parking and drive areas to be located northeast of
East Mulberry Street and South Lemay Avenue in Fort Collins, Colorado. The site is located in
the Southeast 1/4 of Section 12, Township 7 North, Range 69 West of the 6th Principal
Meridian, Larimer County, Colorado.
The purpose of these services is to provide information and geotechnical engineering
recommendations relative to:
• subsurface soil and bedrock conditions
• groundwater conditions
• foundation design and construction
• seismic considerations
• floor slab design and construction
• lateral earth pressures
• pavement design and construction
• earthwork
• drainage
The recommendations contained in this report are based upon the results of field and laboratory
testing, engineering analyses, and experience with similar soil conditions, structures and our
understanding of the proposed project.
PROJECT DESCRIPTION
The project as we understand it is to construct a Home Depot Store with an approximate
102,000 square foot main store facility, an approximate 19,000 squarefoot garden center, an
approximate 7,000 square foot seasonal sales facility and associated loading docks, pickup
canopy and paved parking ad drive areas. Maximum anticipated wall, column and slab loads
1
TABLE OF CONTENTS
Page No.
Letterof Transmittal--------------------------------------------------------------------------------- -------i
INTRODUCTION------------------------ —----------------------------- ------------------------------------------ 1
PROJECT DESCRIPTION ------------------------------- — ---------------------------------------------------- 1
SITE EXPLORATION PROCEDURES---------------------------------------------------------------------2
FieldExploration ------------------- ------------------------------------------------------------------------ 2
LaboratoryTesting --------------------------------------------------------------------------- ---------------- 3
SITECONDITIONS ----------- --------- ------------ —----------- ---------------------------- --------------- - ----- 3
SoilConditions ---------------------------- ---------------------------- -------- ------------------------------- 3
Field and Laboratory Test Results --------------------------------- =----------------------------------- 4
Groundwater Conditions -------------------------- —------------------ —------------------------- =-------- 4
ENGINEERING RECOMMENDATIONS-------------------------------------------------------------------4
Geotechnical Cons iderations ------ --------------------------------------------------------------------- 4
Foundation Systems — Conventional Type Spread Footings ---------------------------------- 5
Floor Slab Design and Construction ------------------------------------------------------------------ 7
Pavement Design and Construction ---- —--- ---------------------------------------------------------- 8
Lateral Earth Pressures ------------ -------------------------------------------------------------------- 11
SeismicConsiderations -------------------------- ------------------------------------------------------- 12
Earthwork------------------------------ -------- ------------------------------------------ --------------- = ---- 12
General Considerations------------------------------------------------------ ------------------------- --12
SitePreparation ------------------- — ------------------------------------------------------------------------ 12
Subgrade Preparation ----------- -------------- ---------------------------------------------------------- 13
Fill Materials and Placement --------------------------------------------------------------------------- 13
Excavation and Trench Construction ---------- ------------------- ---------------------------------- 14
Additional Design and Construction Considerations ------------------------------------------ 14
Exterior Slab Design and Construction -- — -------------------------------------------------------- 14
Underground Utility Systems ------ -------------------------------------------------------------------- 13
CorrosionProtection ---------------------------- ---------------------------------------------------------- 15
Surface Drainage ------------------------------------------------ — ---------------------------------------- 15
GENERALCOMMENTS-------------------------------------------------------------------------------------16
APPENDIX A
Vicinity Map — Figure 1
Boring Location Plan — Figure 2
Bedrock Contour Map — Figure 3
Groundwater Contour Map — Figure 4
Logs of Borings
APPENDIX B
Laboratory Test Results
APPENDIX C
General Notes
Pavement Notes
Geotechnical Engineering Exploration lrerracon
Proposed Home Depot Store
N/E/C East Mulberry Street and South Lemay Avenue
Fort Collins, Colorado
Project No. 20035085
bearing on native soils and/or engineered fill material. Slab -on -grade construction is considered
feasible at the site provided the recommendations set forth in the report are followed.
We appreciate the opportunity to be of service to you on this phase of your project. If you have
any questions concerning this report, or if we may be of further service to you, please do not
hesitate to contact us.
Sincerely,
TERRACON
Daniel R. Lambert, P.E.
Geotechnical Engineer
Copies to: (4) Addressee
(3) Galloway, Romero & Associates
(3) Little & Associates
David A. Richer, P.E.
Geotechnical Engineer/Department Manager
July 14, 2003
Home Depot U.S.A., Inc.
370 Corporate Drive North
Tukwila, Washington 98188
Attn: Naomi Vincent
Irerracon
301 N. Howes • P.O. Box 503 -
Fort Collins, Colorado 80521-0503
(970)484-0359 Fax: (970) 484-0454
Re: Geotechnical Engineering Report
Proposed Home Depot Store #NW0066
Northeast of East Mulberry Street and South Lemay Avenue
Fort Collins, Colorado
Terracon Project No. 20035085
Terracon has completed a geotechnical engineering exploration for the proposed Home Depot
Store and associated paved parking and drive areas to be located northeast of East Mulberry
Street and South Lemay Avenue in Fort Collins, Colorado. This study was performed in general
accordance with our Proposal No. D2002352 dated April 25, 2003.
Terracon performed a comprehensive geotechnical engineering exploration for the Wal"Mart
Super Center Store, in April of 1999 and for the interior roadways in October of 2000. For
further information and findings thereof, please refer to.our "Geotechnical Engineering Reports"
dated July 20, 1999, Project No. 20995107 and October 26, 2000, Project No. 20005217.
The results of our engineering study, including the boring location diagram, laboratory test
results, test boring records, and the geotechnical recommendations needed to aid in the design
and construction of foundations, pavements and other earth connected phases of this project
are attached.
Approximately 4-1/2 to 7-1/2 feet of sandy lean clay fill material was encountered at the surface
of each test boring. Underlying the fill material and extending to the depths explored and/or the
bedrock below was native sands and gravels. Siltstone/claystone was encountered in Test
Boring Nos. 1 through 21 at approximate depths of 17 to 23-feet below existing site grades and
extended to the depths explored, approximately 25-feet. Groundwater was encountered in
various borings across the site at approximate depths of 6-1/2 to 10-feet below existing site
grades when checked approximately 1 to 2 days after initial drilling operations.
Based on the subsurface conditions encountered and the type of construction proposed, it is
recommended the proposed structures be supported by conventional -type spread footings
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Quality Engineering Since 1965
GEOTECHNICAL ENGINEERING REPORT
PROPOSED HOME DEPOT STORE
SITE # NW0066
NORTHEAST OF MULBERRY STREET AND SOUTH LEMAY AVENUE
FORT COLLINS, COLORADO
TERRACON PROJECT NO. 20035085
JULY 14, 2003
�P
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Prepared for.
HOME DEPOT U.S.A., INC.
370 CORPORATE DRIVE NORTH
TUKWILA, WASHINGTON
ATTN: NAOMI VINCENT
Prepared by.
Terracon!
301 North Howes Street
Fort Collins, Colorado 80521
Irerraco