PA9901-LR050708GEOTECHNICAL ENGINEERING STUDY
ADDITION TO WAGON WHEEL PARK
COPPELL, TEXAS
Presented To:
Halff Associates, Inc.
July 2005
PROJECT NO. 117-05-37
-OCMJ
ENGINEERING, INC.
7636 Pebble Drive
Fort Worth, ~l~xas 76118
www.cmjengr, com
July 8, 2005
Report No. 117-05-37
Halff Associates, Inc.
8616 Northwest Plaza Drive
Dallas, Texas 75225-4292
Attn: Mr. Mark McGraw, P.E.
GEOTECHNICAL ENGINEERING STUDY
ADDITION TO WAGON WHEEL PARK
COPPELL, TEXAS
Dear Mr. McGraw:
Submitted here are the results of a geotechnical engineering study for the referenced project.
This study was performed in general accordance with our Proposal No. 05-1045 dated June 2,
2005. The geotechnical services were authorized by Mr. B. David Littleton, P.E., Vice President
of Halff Associates, Inc., on June 13, 2005.
Engineering analyses and recommendations are contained in the text section of the report.
Results of our field and laboratory services are included in the appendix of the report. We would
appreciate the opportunity to be considered for providing the construction consultation services
during the construction phase of this project.
We appreciate the opportunity to be of service to Halff Associates, Inc. Please contact us if you
have any questions or if we may be of further service at this time.
Respectfully submitted,
CMJ ENGI N EERH~---'Tx[NC.
X ~ / ~,.~.~/~ ~ ~AHLE5 M JACKS~
............ , .............
v
Jame~ ~ Sappington IV, E.I.T.
Projec~ Manager
TeXas ~o. ET-31361
copies submi~ed:
~,~,C~ President
Texas No. 46088
(3) Mr. Mark McGraw, P.E.; Halff Associates, Inc.
Phone (817) 284-9400 Fax (817) 589-9993 Metro (817) 589-9992
TABLE OF CONTENTS
1.0 INTRODUCTION ........................................................................................................ 1
1.1 Project Description ............................................................................................... 1
1.2 Purpose and Scope .............................................................................................. 1
1,3 Report Format ..................................................................................................... 1
2.0 FIELD EXPLORATION AND LABORATORY TESTING ...................................................... 2
2.1 Field Exploration ..................................................................................................2
2.2 Laboratory Testing ............................................................................................. 3
3.0 SUBSURFACE CONDITIONS ....................................................................................... 3
3.1 Soil Conditions ................................................................................................... 3
3.2 Ground-Water Observations .................................................................................. 4
4.0 FOUNDATION RECOMMENDATIONS ........................................................................... 4
4.1 General Foundation Considerations ......................................................................... 4
4.2 Potential Vertical Movements ................................................................................. 5
4.3 Stiffened, Monolithic Slab-on-Grade ......................................................................... 5
5.0 RETAINING WALL RECOMMENDATIONS ...................................................................... g
5.1 General Retaining Wall Considerations ..................................................................... 9
5.2 Foundations ........................................................................................................ 9
5.3 Lateral Earth Pressures ....................................................................................... 10
5.4 Wall Backfill Material Requirements ....................................................................... 11
5.5 Below-Grade Drainage Requirements .................................................................... 12
6.0 EXPANSIVE SOIL CONSIDERATIONS ......................................................................... 12
6,1 Site Drainage .....................................................................................................12
6.2 Additional Design Considerations .......................................................................... 13
7.0 SEISMIC CONSIDERATIONS .................................................................................... 13
8.0 EARTHWORK .................................................................... : ................................... 14
8.1 Site Preparation .................................................................................................14
8.2 Placement and Compaction ................................................................................. 14
8.3 Trench Backfill ..................................................................................................15
8,4 Excavation .......................................................................................................16
8.5 Acceptance of Imported Fill .................................................................................. 17
8.6 Soil Corrosion Potential ...................................................................................... 17
8.7 Erosion and Sediment Control .............................................................................. 17
CONSTRUCTION OBSERVATIONS ............................................................................ 17
REPORT CLOSURE ............................................................................................. 18
9.0
10.0
APPENDIX A
Plate
Plan of Borings ............................................................................................................... A.1
Unified Soil Classification .................................................................................................. A.2
Key to Classification and Symbols ....................................................................................... A.3
Logs of Borings .......................................................................................................A.4 - A.5
Free Swell Test Results .................................................................................................... A.6
1.0INTRODUCTION
1.1 Project Description
This report presents the results of a geotechnical engineering study for a proposed pavilion
structure planned near the northwest corner of Wagon Wheel Park in Coppell, Texas. The
construction is understood to be slab-on-ground with a building footprint of approximately 3,600
square feet. A retaining wall with a height of about 4 to 6 feet also is planned on the east side of the
pavilion structure. The approximate locations of the exploration borings are depicted on Plate A.1,
Plan of Borings.
1.2 Purpose and Scope
The purpose of this geotechnical engineering study has been to determine the general subsurface
conditions, evaluate the engineering characteristics of the subsurface materials encountered, and
develop recommendations for the type or types of foundations suitable for the project.
To accomplish its intended purposes, the study has been conducted in the following phases: (1)
drilling sample borings to determine the general subsurface conditions and to obtain samples for
testing; (2) performing laboratory tests on appropriate samples to determine pertinent engineering
properties of the subsurface materials; and (3) performing engineering analyses, using the field
and laboratory data to develop geotechnical recommendations for the proposed construction.
The design is currently in progress and the locations and/or elevations of the structure could
change. Once the final design is near completion (80-percent to 90-percent stage), it is
recommended that CMJ Engineering, Inc. be retained to review those portions of the construction
documents pertaining to the geotechnical recommendations, as a means to determine that our
recommendations have been interpreted as intended.
1.3 Report Format
The text of the report is contained in Sections 1 through 10. All plates and large tables are
contained in Appendix A. The alpha-numeric plate and table numbers identify the appendix in
which they appear. Small tables of less than one page in length may appear in the body of the text
and are numbered according to the section in which they occur.
Repod No. 117-05-37 CMJ ENGINEERING, INC.
Units used in the report are based on the English system and may include tons per square foot
(tsf), kips (1 kip = 1,000 pounds), kips per square foot (ksf), pounds per square foot (psf), pounds
per cubic foot (pcf), and pounds per square inch (psi).
2.0 FIELD EXPLORATION AND LABORATORY TESTING
2.1 Field Exploration
Subsurface materials at the project site were explored by two (2) vertical soil borings drilled to a
depth of 25 feet below existing grade. The borings were drilled using continuous flight augers at
the approximate locations shown on the Plan of Borings, Plate A.1. The boring logs are included
on Plates A.4 and A.5 and keys to classifications and symbols used on the logs are provided on
Plates A.2 and A.3.
Undisturbed samples of cohesive soils were obtained with nominal 3-inch diameter thin-walled
(Shelby) tube samplers at the locations shown on the logs of borings. The Shelby tube sampler
consists of a thin-walled steel tube with a sharp cutting edge connected to a head equipped with a
ball valve threaded for rod connection. The tube is pushed into the soil by the hydraulic pulldown
of the drilling rig. The soil specimens were extruded from the tube in the field, logged, tested for
consistency with a hand penetrometer, sealed, and packaged to limit loss of moisture.
The consistency of cohesive soil samples was evaluated in the field using a calibrated hand
penetrometer. In this test a 0.25-inch diameter piston is pushed into the relatively undisturbed
sample at a constant rate to a depth of 0.25 inch. The results of these tests, in tsf, are tabulated at
respective sample depths on the logs. When the capacity of the penetrometer is exceeded, the
value is tabulated as 4.5+.
Disturbed samples of the noncohesive granular or stiff to hard cohesive materials were obtained
utilizing a nominal 2-inch O.D. split-barrel (split-spoon) sampler in conjunction with the Standard
Penetration Test (ASTM D 1586). This test employs a 140-pound hammer that drops a free fall
vertical distance of 30 inches, driving the split-spoon sampler into the material. The number of
blows required for 18 inches of penetration is recorded and the value for the last 12 inches, or the
penetration obtained from 50 blows, is reported as the Standard Penetration Value (N) at the
appropriate depth on the logs of borings.
Repod No. 117-05-37
2.2 Laboratory Testing
Laboratory soil tests were performed on selected representative samples recovered from the
borings. In addition to the classification tests (liquid limits and plastic limits), moisture content, unit
weight, and unconfined compressive strength tests were performed. Results of the laboratory
classification tests, moisture content, unit weight, and unconfined compressive strength tests
conducted for this project are included on the boring logs.
One swell test was performed on a specimen from a selected sample of the clays. This test was
performed to help in evaluating the swell potential of soils in the area of proposed structure. The
results of the swell tests are presented on Plate A.6.
The above laboratory tests were performed in general accordance with applicable ASTM
procedures, or generally accepted practice.
3.1 Soil Conditions
3.0SUBSURFACE CONDITIONS
Specific types and depths of subsurface strata encountered at the boring locations are shown on
the boring logs in Appendix A. The generalized subsurface stratigraphy encountered in the borings
are discussed below. Note that depths on the borings refer to the depth from the existing grade or
ground surface present at the time of the investigation, and the boundaries between the various
soil types are approximate.
Soils encountered in the borings consist of dark brown to light brown, grayish brown, and light
reddish brown sandy clays and clays of high plasticity. Calcareous nodules and ironstone nodules
were frequently encountered in the overburden soils. The clays encountered in the borings had
tested Liquid Limits (LL) of 49 and 61 and Plasticity Indices (PI) of 35 and 44 and are classified as
CL to CH by the USCS. The various clayey soils were generally very stiff to hard (soil basis) in
consistency with pocket penetrometer readings of 3.5 to over 4.5 tsf. Tested dry unit weight values
ranged from 98 to 111 pcf and unconfined compressive strengths varJed from 3,510 to 9,870 psL
Selected strength tests reflect slickensided or blocky characteristics, which indicate that actual in-
situ strength values may be higher than tested values.
RepoK No. 117-05-37
CMJ ENGINEERING, INC.
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Light brown sands with gravel are present at 17.5 to 18-foot depths and continue to the 25-foot
boring completion depth. This sand is dense to very dense, exhibiting Standard Penetration Test
(SPT) blow counts between 48 blows per foot to 50 blows in 5 inches.
The Atterberg Limits tests indicate the clays at this site are generally highly active with respect to
moisture induced volume changes. Active clays can experience volume changes (expansion or
contraction) with fluctuations in their moisture content.
3.2 Ground-Water Observations
The borings were drilled using continuous flight augers in order to observe ground-water seepage
during drilling. Ground-water seepage was not encountered during drilling and the borings were
dry at completion of drilling operations.
Fluctuations of the ground-water level can occur due to seasonal variations in the amount of
rainfall; site topography and runoff; hydraulic conductivity of soil strata; and other factors not
evident at the time the borings were performed.
4.0 FOUNDATION RECOMMENDATIONS
4.1 General Foundation Considerations
The moisture induced volume changes associated with the highly active clays present at this site
indicate that shallow or near surface footings could be subject to differential movements of a
potentially detrimental magnitude. The most positive foundation system for the proposed
structures would be situated below the zone of most significant seasonal moisture variations. A
deep foundation system transferring column loads to a suitable bearing stratum is considered the
most positive foundation system. However, the use of a monolithic, slab-on-grade can be used if
anticipated movements can be tolerated.
The key to the success of slab performance includes obtaining the proper design parameters for
design, designing the slab for the representative movements anticipated, and construction and
post-construction techniques to reduce the possibility of undue movements. Expansive soils will
neither heave nor shrink unless the actual moisture content of the soil changes. Therefore,
Repod No. 117-05-37
CMJ ENGINEERING, [NC.
4
maintaining as constant a moisture content aside and below slab foundations becomes of
paramount impor[ance to reduction of soil movements.
4.2 Potential Vertical Movements
Variable conditions were encountered during the subsurface exploration. Analyses indicate that
the potential vertical movements of onsite soils due to their expansive characteristics may be up to
4 inches for a dry condition. The higher values of movements will occur where the greater
thicknesses of dryer, more highly plastic clays are present. The actual amount of movement will
depend greatly on the moisture content of the soils prior to construction. In other words, where a
ground-supported floor slab is placed upon moist soils, the future expansive soil movement of
these soils will be limited since these soils exist in a pre-swelled state, and additional moisture will
not cause significant additional heaving of the soils. Conversely, when onsite soils are extremely
dry, moisture will cause significant swelling of these soils.
Upward differential movements due to heaving tend to cause the greatest undue cracking of slabs
and superstructures. Therefore, slabs placed on moist subgrade soils or subgrade soils which are
preconditioned to moist states will exhibit Iow movements, generally tolerable to slab-on-ground
foundations.
4.3 Stiffened, Monolithic Slab-on-Grade
4.3.1 Des{qn Parameters
A stiffened, monolithically placed slab-on-grade foundation, either rebar or post-tensioned, used at
this site must be designed with exterior and interior grade beams to provide sufficient rigidity to
tolerate the differential soil movements. These differential movements typically will occur between
the periphery and interior of the slab-on-grade system. Foundation movements are anticipated to
occur primarily due to post construction heave of the underlying soils but also can occur due to
shrinkage of the clays around the perimeter of the slab. It is recommended that all fill soils be
properly placed and compacted in accordance with this repod, section and Sections 8.0 prior to
foundation installation.
In order for the slab-on-grade structure to be successful, the potential soil movements must be
reduced. Reductions in anticipated movements can be achieved by using methods developed in
this area to reduce on-grade slab movements. A more commonly used method consists of
CMJ ENGINEERINC, INC.
Repod No. 117-05-37
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moisture conditioning the soils and placing a 1-foot select fill pad atop 3 feet of moisture
conditioned soils. Consideration should be given to extending the moisture conditioning process
beyond the building line to include entrances or other areas sensitive to movement. Outside the
structure, a poly barrier capped with a minimum 6 inches of select fill is recommended. The poly
barrier should extend a minimum of 5 feet away from the foundation edge and should slope down
slightly to shed excess moisture away from the structure. The use of these methods will not
eliminate the risk of unacceptable movements.
Slab-on-grade construction only should be considered if slab movement can be tolerated. The
owner must fully understand that if the floor slab is placed on-grade, some movement and resultant
cracking within the floor and interior wall partitions may occur. This upward slab movement and
cracking usually is difficult and costly to repair, and may require continued maintenance expense.
Moisture conditioning is recommended to be achieved by mechanically reworking the clays as
discussed below.
Soil treatments presented in this section are referenced as an alternative to the use of a pier and
structurally suspended grade beam and floor slab. The owner must fully understand that if the
floor slab is placed on-grade, some movement and resultant cracking within the floor and interior
wall partitions may occur. This upward slab movement and cracking usually is difficult and costly
to repair, and may require continued maintenance expense.
The foundation should be designed by a structural engineer familiar with stiffened slabs-on-grade
subject to differential movement. Design parameters are presented below for PVR and differential
swell using the Post-Tensioning Institute's (PTI) slab-on-grade design method, 2nd Edition.
Estimated PVR:
Edge Moisture Variation
Approximate Center Lift:
Approximate Edge Lift:
35 inchesm
5.5 feet
5.0 feet
Differential Swell
Approximate Center Lift:
Approximate Edge Lift:
3.5 inches
1.3 inches
(1) After 3 feet of moisture conditioning with installation of 1 foot select fill cap
Repod No. 117-05-37 CMJ ENGINEERING, INC.
The above post-tensioned design values are based on a 10-year design life. If a greater life is
desired, the structural engineer may increase the values appropriately.
It should be recognized that a post tensioned or conventionally reinforced slab-on-grade foundation
system placed at this site will be subject to differential movements as indicated above. If slab
stiffness is not sufficient to resist the ground movements, these movements can cause cracking of
interior sheet rock walls and exterior brick walls. Poor drainage, water leaks, free water sources,
long-term percolation in recessed planter areas and/or trees can result in greater differential
movements. For example, should leaks develop in underground water or sewer lines or the grades
around the structures are changed and cause ponding of water, unacceptable slab movements
could develop. A greater risk of unsatisfactory foundation performance exists with a slab-on-grade
design than for a drilled shaft design.
Beams may be designed based on an allowable soil bearing pressure of 2,500 pounds per square
foot or less within the shallow soils. The beams should extend at least 12 inches into natural,
undisturbed soil or compacted and tested fill. The beam depth is given in regard to bearing
capacity and is not intended to be a structural recommendation.
The key to the success of this foundation is proper design/construction, and providing control of the
below-slab water. Providing excellent drainage away from the structure, preventing ponding water
aside the slab, and using relatively impermeable backfill to prevent water intrusion via utility line
backfill enhance the slab performance.
4.3.2 Mechanical Reworking of Near-Surface Clays with 1' Select Fill Cap
In general, the procedure is performed as follows:
1. Remove all existing pavements, sudace vegetation, trees and associated root mats, organic
topsoil and any other deleterious material.
2. Excavate surficial clays to a minimum of 3.5 feet below finished grade. Scarify the exposed
clay subgrade, at the base of the excavation, to a depth of 8 inches, adjust the moisture, and
compact at a minimum of three percentage points above optimum moisture to between 93 and
98 percent of Standard Proctor density (ASTM D 698). Over-compaction should not be
allowed.
3. Fill pad to 1 foot below final grade using site excavated or similar clay soils. Compact in
maximum 9-inch loose lifts at a minimum of three percentage points above optimum moisture
to between 93 and 98 percent of Standard Proctor density (ASTM D 698). Over-compaction
should not be allowed.
Report No. 117-05-37 CMJ ENGINEERING, INC.
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Complete pad fill using a minimum of 1 foot of sandy clay/clayey sand, non-expansive select fill
with a Liquid Limit less than 35 and a Plasticity Index (PI) between 5 and 16. The select fill
should be compacted in maximum 9-inch loose lifts at -2 to +3 percentage points of the soil's
optimum moisture content at a minimum of 95 percent of Standard Proctor density (ASTM D
698). The select fill should be placed within 48 hours of completing the installation of the
moisture conditioned soils.
A properly engineered and constructed moisture barrier should be provided beneath the slab-on-
grade.
The key to the success of this foundation is proper design/construction, and providing control of the
below-slab water. Providing excellent drainage away from the structure, preventing ponding water
aside the slab, and using relatively impermeable backfill to prevent water intrusion via utility line
backfill enhance the slab performance.
The following measures also are recommended to provide more uniform movements to
foundations for the proposed structure:
· Provide irrigation systems away from the edge of the building such that any leakage of said
systems will not cause undue localized moisture gain below the slab
· Always provide positive drainage away from the foundation to prevent zones of ponded
water adjacent to the slab
Rainfall is recommended to be collected by gutters and downspouts and transmitted well
away from the structure to prevent water from entering the building subgrade adjacent to
the slab
The owners should be educated in providing a uniform moisture condition adjacent to the
edge of their foundation. This involves sprinkling/watering their foundation during the dry,
hot summers and providing good drainage of excess water away from the foundation during
the wet periods of the year
All utility lines should be properly compacted and it is recommended that a clay plug be
established at the edge of the building line leading out a horizontal distance of 5 feet. The
purpose of this clay is to prevent excess water in a utility ditch backfill from entering the
foundation and causing non-uniform movements
· The floor slab placed at or below existing grade should be provided with a moisture barrier
to prevent wet spots from penetrating through the pervious concrete slab
Trees and shrubs planned around the foundations should be studied to assure that their
root systems wilt not penetrate below the slab and cause undue drying of isolated zones
along the foundation perimeter, potentially causing differential soil movements and resulting
differential slab movements
Repo~ No. 117-05-37
CMJ ENGINEERING, INC.
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Leave outs around the perimeter of the slab foundation should be backfilled in loose lifts not
exceeding 6 to 8 inches, moistened as required, and compacted and tested to ensure a
tight fill of onsite soils exists around the building perimeter
Provide a uniform moisture condition within a 5-foot zone around the building perimeter to
help maintain a more uniform soil moisture content and resulting reduced differential soil
heaving movement below the slab
5.0 RETAINING WALL RECOMMENDATIONS
5/1 General Retaining Wall Considerations
Five geotechnical design criteria must be satisfied in the selection of the type and configuration of
the retaining walls. These criteria are; the wall must have an acceptable factor of safety with
respect to ('1) overturning failure, (2) a sliding (translation) failure, (3) a bearing capacity failure, and
(4) a global (deep-seated) slope failure. In addition, (5) the deformation of the wall caused by
deflection from earth pressure, and from settlement or heave of the foundation soils or backfill
soils, must be within tolerab]e limits during the functional life of the structure.
5.2 Foundations
5.2.1 General Recommendations
The retaining wall foundations should be founded into the natural soils at least 2 feet below lowest
adjacent grade. The retaining wall foundations may be designed for an allowable bearing pressure
of 2.5 ksf, It should be noted that retaining wall foundations are typically subjected to non-uniform
pressure across the foundation, and possibly negative pressure (separation of foundation from soil)
under a portion of the foundation, due to the overturning moment induced by the lateral eadh
pressures. The allowable foundation pressures given above are for the maximum pressure
induced by the foundation loads, and not the average pressure under the foundation base.
Foundations for the retaining walls designed in accordance with these recommendations will have
a minimum factor of safety of 3 with respect to a bearing capacity failure, and should experience a
total settlement of 1 inch or less and a differential settlement of ½ inch or less, after construction,
Report No. 117~05-37 CMJ ENGINEERING, INC.
5.3 Lateral Earth Pressures
5.3.1 General
The retaining walls must be designed for lateral pressures including, but not necessarily limited to,
earth, water, surcharge, swelling, and vibration. In addition, the lateral pressures will be influenced
by whether the backfill is drained or undrained, and above or below the ground-water table.
5.3.2 Equivalent Fluid Pressures
Lateral earth pressures on retaining walls will depend on a variety of factors, including the type of
soils behind the wall, the condition of the soils, and the drainage conditions behind the wall.
Recommended lateral earth pressures expressed as equivalent fluid pressures, per foot of wall
height, are presented in Table 5.3.2-1 for a wall with a level backfill behind the top of the wall. The
equivalent fluid pressure for an undrained condition should be used if a drainage system is not
present to remove water trapped in the backfill and behind the wall. Pressures are provided for at-
rest and active earth pressure conditions. In order to allow for an active condition the top of the
wall(s) must deflect on the order of 0.4 percent.
For the select fill or free draining granular backfill these values assume that a "full" wedge of the
material is present behind the wall. The wedge is defined where the wall backfill limits extend
outward at least 2 feet from the base of the wall and then upward on a 1H:2V slope. For narrower
backfill widths of granular or select fill soils, the equivalent fluid pressures for the on-site soils
should be used.
TABLE 5.3.2-1
At-Rest Equivalent Active Equivalent
Backfill Material Fluid?ressure (pcf) Fluid Pressure (pcf)
Drained ! Undrained Drained Undrained
Excavated on-site clay or
100 110 $5 100
clay fill material
Select fill or on-site soils
meeting material / 65 90 50 85
s~oecifications
Free draining granular 50 I 90 35 80
backfill material
I
CMJ ENGINEERING, INC.
Repor~ No. 117-05-37
10
5.3.3 Additional Lateral Pressures
The location and magnitude of permanent surcharge loads (if present) should be determined, and
the additional pressure generated by these loads such as the weight of construction equipment
and vehicular loads that are used at the time the structures are being built must also be considered
in the design. The effect of this or any other surcharge loading may be accounted for by adding an
additional uniform load to the full depth of the side walls equivalent to one-half of the expected
vertical surcharge intensity for select backfill materials, or equal to the full vertical surcharge
intensity for clay backfill. The equivalent fluid pressures, given here, do not include a safety factor.
Analysis of surcharge loads (if any) should be performed on a case-by-case basis. This is not
included in the scope of this study. These services can be provided as additional services upon
request.
5.4 Wall Backfill Material Requirements
Granular Wall Backfill: All free draining granular wall backfill material should be a crushed stone,
sand/gravel mixture, or sand/crushed stone mixture. The material should have less than 3 percent
passing the No. 200 sieve and less than 30 percent passing the No. 40 sieve. The minus No. 40
sieve material should be non-plastic Granular wall backfill should not be water jetted during
installation.
Select Fill Behind Walls: All wall select backfill should consist of clayey sand and/or sandy clay
material with a plasticity index of 16 or less, with a liquid limit not exceeding 35. The select fill
should be placed in maximum 8-inch lifts and compacted to between 95 and 100 percent of
Standard Proctor density (ASTM D 698) within a moisture range of plus to minus 3 percentage
points of the optimum moisture. Compaction within five feet of the walls should be accomplished
using hand compaction equipment and should be compacted between 90 and 95 percent of the
Standard Proctor Density.
On-Site Soil Backfill: For wall backfill areas with site-excavated materials or similar imported
materials, all oversized fragments larger than four inches in maximum dimension should be
removed from the backfill materials prior to placement. The backfill should be free of all organic
and deleterious materials, and should be placed in maximum 8-inch compacted lifts at a minimum
of 95 percent of Standard Proctor density (ASTM D 698) within a moisture range of plus to minus
3 percentage points of optimum moisture. Compaction within five feet of the walls should be
CMJ ENGINEERING, INC.
Repod No. 117-05-37
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accomplished using hand compaction equipment, and should be bebveen 90 and 95 percent of the
Standard Proctor Density.
5.5 Below-Grade Drainage Requirements
The design recommendations presented above assume hydrostatic pressure will not develop
behind the retaining wall. In order to achieve the "above water table" condition for lateral earth
pressure for Iow-permeability walls (concrete, masonry, etc.), a vertical drainage blanket or
geocomposite drainage member must be installed adjacent to the wall on the backfill side. The
drainage must be connected to an outlet drain at the base of the wall, or to the sump/pump system.
Drainage could be provided using a collector pipe or weep holes near the base of the retaining
wall. Drains should be properly filtered to minimize the potential for erosion through these drains,
and/or the plugging of drain lines. Design or specific recommendations for drainage members is
beyond the scope for this study. These services can be provided as an additional service upon
request. In order to achieve the "drained" condition, the entire backfill material must be free
draining, or the backfill-wall geometry must be such that the backfill will not become saturated from
rainfall, ground water, adjacent water courses, or other sources.
6.0 EXPANSIVE SOIL CONSIDERATIONS
6.1 Site Drainage
An important feature of the project is to provide positive drainage away from the proposed
buildings. If water is permitted to stand next to or below the structure, excessive soil movements
(heave) can occur. This could result in differential floor slab or foundation movement.
A well-designed site drainage plan is of utmost importance and surface drainage should be
provided during construction and maintained throughout the life of the structure. Consideration
should be given to the design and location of gutter downspouts, planting areas, or other features
which would produce moisture concentration adjacent to or beneath the structure or paving.
Consideration should be given to the use of self-contained, watertight planters. Joints next to the
structure should be sealed with a flexible joint sealer to prevent infiltration of surface water, Proper
maintenance should include periodic inspection for open joints and cracks and resealing as
necessary.
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Rainwater collected by the gutter system should be transported by pipe to a storm drain or to a
paved area. If downspouts discharge next to the structure onto flatwork or paved areas, the area
should be watertight in order to eliminate infiltration next to the building.
6.2 Additional Design Considerations
The following information has been assimilated after examination of numerous projects constructed
in active soils throughout the area. It is presented here for your convenience. If these features are
incorporated in the overall design of the project, the pedormance of the structure should be
improved.
· Special consideration should be given to completion items outside the building area, such
as stairs, sidewalks, signs, etc. They should be adequately designed to sustain the
potential vertical movements mentioned in the report.
Roof drainage should be collected by a system of gutters and downspouts and
transmitted away from the structure where the water can drain away without entering the
building subgrade.
· Sidewalks should not be structurally connected to the building. They should be sloped
away from the building so that water will drain away from the structure.
The paving and the general ground surface should be sloped away from the building on
all sides so that water will always drain away from the structure. Water should not be
allowed to pond near the building after the slab has been placed.
Every attempt should be made to limit the extreme wetting or drying of the subsurface
soils since swelling and shrinkage will result. Standard construction practices of providing
good surface water drainage should be used. A positive slope of the ground away from
the foundation should be provided to carry off the run-off water both during and after
construction.
Backfill for utility lines or along the perimeter beams should consist of on-site material so
that they will be stable. If the backfill is too dense or too dry, swelling may form a mound
along the ditch line. If the backfill is too loose or too wet, settlement may form a sink along
the ditch line. Either case is undesirable since several inches of movement is possible
and floor cracks are likely to result. The soils should be processed using the previously
discussed compaction criteria.
7.0 SEISMIC CONSIDERATIONS
Based on the conditions encountered in the borings for the above referenced project the IBC-2000
site classification is TYPE C for seismic evaluation,
Report No. 11%05-37
CMJ ENGINEERING, INC.
13
8.0 EARTHWORK
8.1 Site Preparation
The existing ground surface should be stripped of vegetation, roots, old construction debris, and
other organic material. It is estimated that the depth of stripping will be on the order of 4 to 6
inches. The actual stripping depth should be based on field observations with particular attention
given to old drainage areas, uneven topography, and excessively wet soils. The stripped areas
should be observed to determine if additional excavation is required to remove weak or otherwise
objectionable materials that would adversely affect the fill placement or other construction
activities.
The subgrade should be firm and able to support the construction equipment without displacement.
Soft or yielding subgrade should be corrected and made stable before construction proceeds. The
subgrade should be proof rolled to detect soft spots, which if exist, should be excavated to provide
a firm and otherwise suitable subgrade. Proof rolling should be performed using a heavy
pneumatic tired roller, loaded dump truck, or similar piece of equipment. The proof rolling
operations should be observed by the project geotechnical engineer or his/her representative.
Prior to fill placement, the subgrade should be scarified to a minimum depth of 6 inches, its
moisture content adjusted, and recompacted to the moisture and density recommended for fill. In
areas of perched water or pumping subgrade, it may be necessary to install sub-pavement drains
or edge drains. Installation of a bi-axial geogrid capped with flexbase or crushed stone also may
be necessary to stabilize soft, pumping, or unusual subgrade soil conditions. This decision should
be made during construction to verify the need.
8.2 Placement and Compaction
Fill material should be placed in loose lifts not exceeding 8 inches in uncompacted thickness. The
uncompacted lift thickness should be reduced to 4 inches for structure backfill zones requiring
hand-operated power compactors or small self-propelled compactors. The fill material should be
uniform with respect to material type and moisture content. Clods and chunks of material should
be broken down and the fill material mixed by disking, blading, or plowing, as necessary, so that a
material of uniform moisture and density is obtained for each lift. Water required for sprinkling to
bring the fill material to the proper moisture content should be applied evenly through each layer.
CMJ ENGINEERING, INC.
RepodNo 117-05-37
14
The on-site soils are suitable for use in site grading. Imported fill material should be clean soil with
a Liquid Limit less than 50 and no rock greater than 4 inches in maximum dimension. The fill
materials should be free of vegetation and debris.
The fill material should be compacted to a density ranging from 95 to 100 percent of maximum dry
density as determined by ASTM D 698, Standard Proctor. In conjunction with the compacting
operation, the fill material should be brought to the proper moisture content. The moisture content
for general earth fill should range from 2 percentage points below optimum to 5 percentage points
above optimum (-2 to +5). These ranges of moisture contents are given as maximum
recommended ranges. For some soils and under some conditions, the contractor may have to
maintain a more narrow range of moisture content (within the recommended range) in order to
consistently achieve the recommended density.
Field density tests should be taken as each lift of fill material is placed. As a guide, one field
density test per lift for each 5,000 square feet of compacted area is recommended. For small areas
or critical areas the frequency of testing may need to be increased to one test per 2,500 square
feet. A minimum of 2 tests per lift should be required. The earthwork operations should be
observed and tested on a continuing basis by an experienced geotechnician working in conjunction
with the project geotechnical engineer.
Each lift should be compacted, tested, and approved before another lift is added. The purpose of
the field density tests is to provide some indication that uniform and adequate compaction is being
obtained. The actual quality of the fill, as compacted, should be the responsibility of the contractor
and satisfactory results from the tests should not be considered as a guarantee of the quality of the
contractor's filling operations.
8.3 Trench Backfill
Trench backfill for pipelines or other utilities should be properly placed and compacted. Overly
dense or dry backfill can swell and create a mound along the completed trench line. Loose or wet
backfill can settle and form a depression along the completed trench line. Distress to overlying
structures, pavements, etc. is likely if heaving or settlement occurs. On-site soil fill material is
recommended for trench backfill. Care should be taken not to use free draining granular material,
to prevent the backfilled trench from becoming a french drain and piping surface or subsurface
CMJ ENGINEERING, INC.
Repod No. 117-05-37
15
water beneath structures, pipelines, or pavements. If a higher class bedding material is required
for the pipelines, a lean concrete bedding will limit water intrusion into the trench and will not
require compaction after placement. The soil backfill should be placed in approximately 4- to 6-
inch loose lifts. The density and moisture content should be as recommended for fill in Section 8.2,
Placement and Compaction, of this report. A minimum of one field density test should be taken per
lift for each 150 linear feet of trench, with a minimum of 2 tests per lift.
8.4 Excavation
The side slopes of excavations through the overburden soils should be made in such a manner to
provide for their stability during construction. Existing structures, pipelines or other facilities, which
are constructed prior to or during the currently proposed construction and which require
excavation, should be protected from loss of end bearing or lateral suppod.
Temporary construction slopes and/or permanent embankment slopes should be protected from
surface runoff water. Site grading should be designed to allow drainage at planned areas where
erosion protection is provided, instead of allowing surface water to flow down unprotected slopes.
Permanent slopes at the site should be as flat as practical to reduce creep and occurrence of
shallow slides. The following slope angles are recommended as maximums.
TABLE 8.4-1 Maximum Slope Angles
Height (ft.) Horizontal to Vertical
0-3 1:1
3 - 6 2:1
6 - 9 3:1
> 9 4:1
The above angles refer to the total height of a slope. Site improvement should be maintained
away from the top of the slope to reduce the possibility of damage due to creep or shallow slides.
Trench safety recommendations are beyond the scope of this report. The contractor must comply
with all applicable safety regulations concerning trench safety and excavations including, but not
limited to. OSHA regulations.
CN{J ENGINEERING, INC.
Repod No. 117-05-37
16
8.5 Acceptance of Imported Fill
Any soil imported from off-site sources should be tested for compliance with the recommendations
for the particular application and approved by the project geotechnical engineer prior to the
materials being used. The owner should also require the contractor to obtain a written, notarized
certification from the landowner of each proposed off-site soil borrow source stating that to the best
of the landowner's knowledge and belief there has never been contamination of the borrow source
site with hazardous or toxic materials, The certification should be furnished to the owner prior to
proceeding to furnish soils to the site. Soil materials derived from the excavation of underground
petroleum storage tanks should not be used as fill on this project.
8.6 Soil Corrosion Potential
Specific testing for soil corrosion potential was not included in the scope of this study. However,
based upon past experience on other projects in the vicinity, the soils at this site may be corrosive.
Standard construction practices for protecting metal pipe and similar facilities in contact with these
soils should be used.
8.7 Erosion and Sediment Control
All disturbed areas should be protected from erosion and sedimentation during construction, and
all permanent slopes and other areas subject to erosion or sedimentation should be provided with
permanent erosion and sediment control facilities. All applicable ordinances and codes regarding
erosion and sediment control should be followed.
9.0CONSTRUCTION OBSERVATIONS
In any geotechnical investigation, the design recommendations are based on a limited amount of
information about the subsurface conditions. In the analysis, the geotechnical engineer must
assume the subsurface conditions are similar to the conditions encountered in the borings.
However, quite often during construction anomalies in the subsurface conditions are revealed.
Therefore, it is recommended that CMJ Engineering, Inc. be retained to observe earthwork and
foundation installation and perform materials evaluation during the construction phase of the
project. This enables the 9eotechnical engineer to stay abreast of the project and to be readily
available to evaluate unanticipated conditions, to conduct additional tests if required and, when
necessary, to recommend alternative solutions to unanticipated conditions, Until these
Repod No. 117-05-37 CMJ ENGINEERING, INC.
17
construction phase services are performed by the project geotechnical engineer, the
recommendations contained in this report on such items as final foundation bearing elevations,
proper soil moisture condition, and other such subsudace related recommendations should be
considered as preliminary.
It is proposed that construction phase observation and materials testing commence by the project
geotechnical engineer at the outset of the project. Experience has shown that the most suitable
method for procuring these services is for the owner or the owner's design engineers to contract
directly with the project geotechnical engineer. This results in a clear, direct line of communication
between the owner and the owner's design engineers and the geotechnical engineer.
10.0 REPORT CLOSURE
The boring logs shown in this repod contain information related to the types of soil encountered at
specific locations and times and show lines delineating the interface between these materials. The
logs also contain our field representative's interpretation of conditions that are believed to exist in
those depth intervals between the actual samples taken. Therefore, these boring logs contain both
factual and interpretive information. Laboratory soil classification tests were also performed on
samples from selected depths in the borings. The results of these tests, along with visual-manual
procedures were used to generally classify each stratum. Therefore, it should be understood that
the classification data on the logs of borings represent visual estimates of classifications for those
portions of each stratum on which the full range of laboratory soil classification tests were not
performed. It is not implied that these logs are representative of subsurface conditions at other
locations and times.
With regard to ground-water conditions, this report presents data on ground-water levels as they
were observed during the course of the field work. In particular, water level readings have been
made in the borings at the times and under conditions stated in the text of the report and on the
boring logs. tt should be noted that fluctuations in the level of the ground-water table can occur
with passage of time due to variations in rainfall, temperature and other factors. Also, this report
does not include quantitative information on rates of flow of ground water into excavations, on
pumping capacities necessary to dewater the excavations, or on methods of dewatering
excavations. Unanticipated soil conditions at a construction site are commonly encountered and
cannot be fully predicted by mere soil samples, test borings or test pits. Such unexpected
CMJ ENGINEERING, INC.
RepodNo 117-05-37
18
conditions frequently require that additional expenditures be made by the owner to attain a properly
designed and constructed project. Therefore, provision for some contingency fund is
recommended to accommodate such potential extra cost.
The analyses, conclusions and recommendations contained in this report are based on site
conditions as they existed at the time of our field investigation and further on the assumption that
the exploratory borings are representative of the subsurface conditions throughout the site; that is,
the subsurface conditions everywhere are not significantly different from those disclosed by the
borings at the time they were completed. If, during construction, different subsurface conditions
from those encountered in our borings are observed, or appear to be present in excavations, we
must be advised promptly so that we can review these conditions and reconsider our
recommendations where necessary. If there is a substantial lapse of time between submission of
this report and the start of the work at the site, if conditions have changed due either to natural
causes or to construction operations at or adjacent to the site, or if structure locations, structural
loads or finish grades are changed, we urge that we be promptly informed and retained to review
our repod to determine the applicability of the conclusions and recommendations, considering the
changed conditions and/or time lapse.
Further, it is urged that CMJ Engineering, Inc. be retained to review those portions of the plans and
specifications for this particular project that pertain to earthwork and foundations as a means to
determine whether the plans and specifications are consistent with the recommendations
contained in this report. In addition, we are available to observe construction, particularly the
compaction of structural fill, or backfill and the construction of foundations as recommended in the
report, and such other field observations as might be necessary.
The scope of our services did not include any environmental assessment or investigation for the
presence or absence of wetlands or hazardous or toxic materials in the soil, surface water, ground
water or air, on or below or around the site.
This report has been prepared for use in developing an overall design concept. Paragraphs,
statements, test results, boring logs, diagrams, etc. should not be taken out of context, nor utilized
without a knowledge and awareness of their intent within the overall concept of this report. The
reproduction of this report, or any part thereof, supplied to persons other than the owner, should
indicate that this study was made for design purposes only and that verification of the subsurface
CMJ ENGINEERING, INC.
Report No 117-05-37
19
conditions for purposes of determining difficulty of excavation, trafficability, etc. are responsibilities
of the contractor.
This report has been prepared for the exclusive use of Halff Associates, Inc. for specific application
to design of this project. The only warranty made by us in connection with the services provided is
that we have used that degree of care and skill ordinarily exercised under similar conditions by
reputable members of our profession practicing in the same or similar locality. No other warranty,
expressed or implied, is made or intended. These recommendations should be reviewed once a
grading plan is finalized.
CMJ ENGINEERING, INC.
Report No. 117-05-37
2O
: /
I i
I B-2
Bc~,ng
~ I
Ill CMJ PLAN OF BORINGS
--~ E~4Gn~EV.~G~ L,~C. ADDITION TO WAGON WHEEL PARK PLA TE
COPPELL, TEXAS A. !
Chid PROJECT NO. 117-05-57
Grp. Typical Names Laboratory Classification Criteria
Divisions Sym.
~' Well-graded gravels, gravel- ~ (D~o)~,
¢ ® GW sand mixtures, little or no =~ c =D6°~ greater than 4: Cc ............... between I and 3
~ ~ fines ~ ~ D,~ D~oxD~o
· - · ~ Poorly graded gravels, gravel ~ ¢ ~ ~
~ -- ~ ¢ ~ ~ Not meeting all gradation requirements for GW
e O ~ GP sand mixtures, little or no $
> ~ fines ~ ~ O ~
~ ~ Liquid and Plastic limits
~ GM ~ ~ ! ~ ~ below"A" line or P,I.
mixtures ~ ~ ~ :: ~ plotting in hatched zone
~ ~ ~ greater than 4
~ ~ ~ · o ~ :: ~ borderline cases
.~ % N O ~ :: e Liquid and Plastic limits
~ Clayey gravels, gravel-sand- '~ ~ . . o requfring use of dual
~ ~ GC ~ d ~ above "A" line with P.I.
~ ~ clay mixtures '~ z :: ~ symbols
Well-graded sands, gravelly ~ ~
~ _ ~ ~ Poorly graded sands; ~ ~ j ~
'~ O ~ SP gravelly sands, little or no c · Not meeting all gradation requirements for SW
® ~ fines ~
~ ~. ~ ~ ~ Liquid and Plastic limits
Silty sands, sand-silt ~ E ~
~ ~ SM ~ ~ ~ ~ ~ below"A"line or P.I, less Liquid and plastic limits
~ E mixtures ~ 8 ~ ~ ~ ~ than4
~ ~ · plotting between 4 and 7
~ Z ~ ~ ~ requiring use of dual
~ ~ = L~quid and Plastic limits
~ ~ '~ ~ SC Clayey sands, sand-clay = ~ ~ symboJs
, c c ~ above "A" line with P.I.
Inorganic silts and vew fine
~ ML clayey fine sands, or clayey
E silts with slight plasticity
~ ~ 60
~ ~ Inorganic clays of Iow to ~
~ e medium plasticity, gravelly
c -- CL , ~ /
~ OL Organic silts and organic silty
clays of Iow plasticity i / ~
~ Inorganic silts, micaceous or ~ ~ _~
~%¢ =~ silty soils, elastic silts 2( CL ~*~
~ ~ Inorganic clays of high ~
~ ~ CH plasticity, fat clays 1E ~
~ Organic clays of medium to 0
~ h~gh plasticity, organic silts
~ '~ Pt Peat and ether highJy organic Plasticity Char[
~ ~ soils
~OII CLASSIFICATION SYSTEM PLATE A.2
/
CL-ML ~ MLal d OL
iSOIL OR ROCK 'r'YPES
TERMS DESCRIBING CONSISTENCY, CONDITION, AND STRUCTURE OF SOIL
Fine Grained Soils (More than 50% Passing No 200 Sieve)
Descriptive Item Penetrometer Reading, (tsf)
Soft 0.0 to 1.0
Firm 1,0 to 1.5
Stiff 1 5 to 3.0
Very Stiff 3.0 to 4,5
Hard 4.5+
Coarse Grained Soils (More than 50% Retained on No 200 Sieve)
Penetration Resistance Descriptive Item Relative Density
(blows/foot)
0 to 4 Very Loose 0 to 20%
4 to 10 Loose 20 to 40%
10 to 30 Medium Dense 40 to 70%
30 to 50 Dense 70 to 90%
Over 50 Very Dense 90 to 100%
Soil Structure
Calcareous
Slickensided
Laminated
Fissured
Interbedded
Contains appreciable deposits of calcium carbonate; generally nodular
Having inclined planes of weakness that are slick and glossy in appearance
Composed of thin layers of varying color or texture
Containing cracks, sometimes filled with fine sand or silt
Composed of alternate layers of different soil types, usually in approximately equal proportions
TERMS DESCRIBING PHYSICAL PROPERTIES OF ROCK
Hardness and Degree of Cementation
Very Soft or Plastic
Soft
Moderately Hard
Hard
Very Hard
Poorly Cemented or Friable
Cemented
Can be remolded in hand; corresponds in consistency up to very stiff in soils
Can be scratched with fingernail
Can be scratched easily with knife; cannot be scratched with fingernail
Difficult to scratch with knife
Cannot be scratched with knife
Easily crumbled
Bound together by chemically precipitated material; Quartz, calcite, dolomite, siderite,
and iron oxide are common cementing materials, and iron oxide are common cementing materials.
Degree of Weathering
Unweathered
Slightly Weathered
Weathered
Extremely Weathered
Rock in its natural state before being exposed to atmospheric agents
Noted predominantly by color change with no disintegrated zones
Complete color change with zones of slightly decomposed rock
Complete color change with consistency, texture, and general appearance approaching soil
KEY TO CLASSIFICATION AND .~YMR~I .~ o~ ^TO ^ '~
_ 117-05-37 -
See Plate A.1
Completion Completion
Depth 25.0' Date %1-05
Sur~hce Elevation
h'/A
erojcct Addition to Wagon Wheel Par~.
Coppell, Texas
Water Observations
Dry during drilling; dry at completion
Type
Rig: B-53, w/6" CFA
Stratum Description
CLAY, dark brown and brown, w/ironstone nodules,
very stiff to hard
grades brown and light brown, 2' to 3'
-w/ calcareous nodules, slJckensided, 2' to 13'
-grades light brown, 3' lo IY
SANDY CLAY, light brown m~d light reddish
brown, w/calcareous nodules m~d ironstains, hard
SAND, light brown, w/gravel, dense
LOG OF BORLNG NO. B-1 PLATE A.4
~roject No. [ Bonng
[~17-05-37 LB-2
LocatYm
See Plate A. 1
Completion ~ompletio:~
Depth 25.0' ate 7-1-05
N/A
dt.ojcct Addition to Wagon Wheel Parr
Coppell, Texas
Water Observations
Dry during drilling; dry at completion
Type
Rig: B-53, w/6" CFA
CMJ ENG[NEERENG tqN(; t
Stratum Description
CLAY, dark brown and grayish brown, w/
calcareous nodules, very stiff to hard
w/ironstone nodules, 0' to 4'
grades light brown and dm-k brown, 2' to 4'
-grades light brown, w/ironstains, slickensided, 4' to
13'
SANDY CLAY, light bro,~n, w~ calcareous nodules
and ironstains, hard
SAND, light brown, w, gravel, very dense
LOG OF BORING NO. B-2 PLATE A.5
FREE SWELL TEST RESULTS
Project:
Project No.:
Addition to Wagon Wheel Park
Coppell, Texas
117-05-37
Free swell tests performed at approximate overburden pressure
CMJ ENGINEERING, INC. PLATE