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GEOTECHNICAL ENGINEERING STUDY
PROPOSED 4-STORY HOTEL
CORPUS CHRISTI, TEXAS
Prepared by:
Tolunay-Wong Engineers, Inc.
826 South Padre Island Drive
Corpus Christi, Texas 78416
January 10, 2017
Project No. 16.53.076 / Report No. 13604
TWE Project No. 16.53.076
Report No. 13604
i
TABLE OF CONTENTS
1 INTRODUCTION AND PROJECT DESCRIPTION 1-1
1.1 Introduction 1-1
1.2 Project Description 1-1
2 PURPOSE AND SCOPE OF SERVICES 2-1
3 FIELD PROGRAM 3-1
3.1 Soil Borings 3-1
3.2 Drilling Methods 3-1
3.3 Soil Sampling 3-1
3.4 Boring Logs 3-2
3.5 Groundwater Measurements 3-2
4 LABORATORY SERVICES 4-1
5 SITE AND SUBSURFACE CONDITIONS 5-1
5.1 General 5-1
5.2 Site Description and Surface Conditions 5-1
5.3 Subsurface Conditions 5-1
5.4 Subsurface Soil Properties 5-1
5.5 Groundwater Observations 5-2
5.6 Shrink / Swell Potential 5-3
6 FOUNDATION RECOMMENDATIONS 6-1
6.1 Discussion 6-1
6.2 Drilled and Underreamed Piers 6-1
6.3 Grade Beams 6-3
6.4 Lightly Loaded Interior Floor Slabs 6-4
7 EARTHWORK CONSIDERATIONS 7-1
7.1 Subgrade Preparation and Structural Select Fill 7-1
7.2 Drainage 7-2
8 PAVEMENT DESIGN RECOMMENDATIONS 8-1
8.1 New Pavement Sections 8-1
8.2 Pavement Section Materials 8-3
8.3 Pavement Drainage and Maintenance 8-4
9 LIMITATIONS AND DESIGN REVIEW 9-1
9.1 Limitations 9-1
9.2 Design Review 9-1
9.3 Construction Monitoring 9-1
9.4 Closing Remarks 9-1
TWE Project No. 16.53.076
Report No. 13604
ii
TABLES AND APPENDICES
TABLES
Table 4-1 Laboratory Testing Program 4-1
Table 5-1 Groundwater Level Measurements 5-2
Table 5-2 General Relationship between P.I. and Shrink/Swell Potential 5-3
Table 6-1 Material Excavation and Replacement with Resulting PVR 6-4
Table 7-1 Compaction Equipment and Maximum Lift Thickness 7-1
Table 8-1 Vehicle Classification and Traffic Loading 8-1
Table 8-2 Rigid Pavement Design Values 8-2
Table 8-3 Recommended Minimum Typical Rigid Pavement Thicknesses 8-2
Table 8-4 Rigid Pavement Components 8-3
APPENDICES
Appendix A: Soil Boring Location Plan
TWE Drawing No. 16.53.076-1
Appendix B: Log of Project Borings and a Key to
Terms and Symbols used on Boring Logs
TWE Project No. 16.53.076
1-1 Report No. 13604
1 INTRODUCTION AND PROJECT DESCRIPTION
1.1 Introduction
This report presents the results of our geotechnical engineering study performed for the proposed
new 4-story hotel in Corpus Christi, Texas. Our geotechnical engineering study was conducted in
accordance with TWE Proposal No. P16-C076, dated August 30, 2016, and authorized by Mr.
Bhakta.
1.2 Project Description
The project involves construction of a new hotel with associated parking and driveway areas. The
new building will be four-stories high with a footprint of about 70-ft. by 230-ft. We understand
that the structure will have a lightly loaded interior floor slab supported by compacted structural
fill material with the superstructure concentrated loads supported by drilled piers. We assume
maximum structural loads will be on the order of 8 to 9 klf (klf = kips per linear foot) for load
bearing walls, and 150 to 200-kips (1 kip = 1,000 lbs.) for concentrated columns. Additionally, an
outdoor pool will be constructed on the south side of the hotel. The finished floor elevation of the
new building will be approximately 2.5-ft. above the existing natural grade at the site. Area
paving is planned to be reinforced concrete and will be primarily subjected to light traffic
conditions (automobiles and light trucks) with occasional delivery truck and solid waste disposal
truck traffic.
TWE Project No. 16.53.076 2-1 Report No. 13604
2 PURPOSE AND SCOPE OF SERVICES
The purposes of our geotechnical engineering study were to investigate the soil and groundwater
conditions within the project site and to provide geotechnical design and construction
recommendations for the proposed facility.
Our scope of services performed for the project consisted of:
1. Drilling two (2) soil borings to depths of 25-ft. & 50-ft. within the project site to
evaluate subsurface stratigraphy and groundwater conditions;
2. Performing geotechnical laboratory tests on recovered soil samples to evaluate the
physical and engineering properties of the strata encountered;
3. Providing geotechnical design and construction recommendations for suitable
foundation system for support of the new hotel;
4. Providing geotechnical design recommendations for rigid (concrete) pavement
sections including subgrade preparation and required component thicknesses; and,
5. Providing geotechnical construction recommendations including site and subgrade
preparation, excavation considerations, fill and backfill requirements, compaction
requirements, foundation installation and overall quality control monitoring, testing
and inspection services.
Our scope of services did not include any environmental assessments for the presence or absence
of wetlands or of hazardous or toxic materials within or on the soil, air or water within this
project site. Any statements in this report or on the boring logs regarding odors, colors or
unusual or suspicious items or conditions are strictly for the information of the Client. A
geological fault study was also beyond the scope of our services associated with this geotechnical
engineering study.
TWE Project No. 16.53.076 3-1 Report No. 13604
3 FIELD PROGRAM
3.1 Soil Borings
TWE conducted an exploration of subsurface soil and groundwater conditions at the project site
on November 23, 2016 by drilling, sampling, and logging two (2) soil borings to depths of 25-ft.
and 50-ft. below existing grades. The soil boring locations are presented on TWE Drawing No.
16.53.076-1, and can be found in Appendix A of this report. Drilling and sampling of the soil
borings were performed using conventional truck-mounted drilling equipment. Our field
personnel coordinated the field activities and logged the boreholes. The boring locations were
staked at the site by TWE and the latitude and longitude for each boring location were
determined by hand held GPS device and are presented on the boring logs.
3.2 Drilling Methods
Field operations were performed in general accordance with the Standard Practice for Soil
Investigation and Sampling by Auger Borings [American Society for Testing and Materials
(ASTM) D 1452]. The soil borings were drilled using a truck-mounted drilling rig equipped with
a rotary head. The boreholes were advanced using dry-auger and hollow stem drilling methods.
Samples were obtained continuously from existing ground surface to a depth of 12-ft., at the 13-
ft. to 15-ft. depth interval and at intervals of 5-ft. thereafter until the boring completion depths
were reached.
3.3 Soil Sampling
Fine-grained, cohesive soil samples were recovered from the soil borings by hydraulically pushing
3-in diameter, thin-walled Shelby tubes a distance of about 24-in. The field sampling procedures
were conducted in general accordance with the Standard Practice for Thin-Walled Tube Sampling
of Soils (ASTM D 1587). Our geotechnician visually classified the recovered soils and obtained
field strength measurements using a pocket penetrometer. A factor of 0.67 is typically applied to
the penetrometer measurement to estimate the undrained shear strength of the Gulf Coast cohesive
soils. The samples were extruded in the field, wrapped in foil, placed in moisture sealed
containers and protected from disturbance prior to transport to the laboratory.
Cohesionless and semi-cohesionless samples were collected with the standard penetration test
(SPT) sampler driven 18-in by blows from a 140-lb hammer falling 30-in in accordance with the
Standard Test Method for Standard Penetration Test (SPT) and Spilt-Barrel Sampling of Soils
(ASTM D 1586). The number of blows required to advance the sampler three (3) consecutive 6-
in depths are recorded for each corresponding sample on the boring logs. The N-value, in blows
per foot, is obtained from SPTs by adding the last two (2) blow count numbers. The
compactness of cohesionless and semi-cohesionless samples are inferred from the N-value. The
samples obtained from the split-barrel sampler were visually classified, placed in moisture sealed
containers and transported to our laboratory.
The recovered soil sample depths with corresponding pocket penetrometer measurements and
SPT blowcounts are presented on the boring logs in Appendix B.
TWE Project No. 16.53.076 3-2 Report No. 13604
3.4 Boring Logs
Our interpretations of general subsurface soil and groundwater conditions at the soil boring
locations are included on the boring logs. Our interpretations of the soil types throughout the
boring depths and the locations of strata changes were based on visual classifications during field
sampling and laboratory testing results in accordance with Standard Practice for Classification
of Soils for Engineering Purposes (Unified Soil Classification System) (ASTM D 2487) and
Standard Practice for Description and Identification of Soils (Visual-Manual Procedure) (ASTM
D 2488).
The boring logs include the type and interval depth for each sample along with its corresponding
pocket penetrometer measurements and SPT blow counts. The boring logs and a key to terms
and symbols used on boring logs are presented in Appendix B.
3.5 Groundwater Measurements
Groundwater level measurements were attempted in the open boreholes during dry-auger drilling.
Water level readings were attempted in the open boreholes when groundwater was first
encountered and after a ten (10) to fifteen (15) minute time period. The groundwater
observations are summarized in Section 5.5 of this report entitled “Groundwater Observations.”
TWE Project No. 16.53.076 4-1 Report No. 13604
4 LABORATORY SERVICES
A laboratory testing program was conducted on selected samples to assist in classification and
evaluation of the physical and engineering properties of the soils encountered in the project borings.
Laboratory tests were performed in general accordance with ASTM International standards. The
types of the laboratory tests performed are presented in Table 4-1. A brief description of the
testing methods is listed below.
Table 4-1: Laboratory Testing Program
Test Description Test Method
Amount of Material in Soils Finer than No. 200 Sieve ASTM D 1140
Unconfined Compressive Strength of Cohesive Soil (UC) ASTM D 2166
Water (Moisture) Content of Soil ASTM D 2216
Liquid Limit, Plastic Limit and Plasticity Index of Soils ASTM D 4318
Density (Unit Weight) of Soil Specimens ---
Amount of Materials in Soils Finer than No. 200 (75-µm) Sieve (ASTM D 1140)
This test method determines the amount of materials in soils finer than the No. 200 (75-µm)
sieve by washing. The loss in weight resulting from the wash treatment is presented as a
percentage of the original sample and is reported as the percentage of silt and clay particles in the
sample.
Unconfined Compressive Strength of Cohesive Soil (ASTM D 2166)
This test method determines the unconfined compressive (UC) strength of cohesive soil in the
undisturbed or remolded condition using strain-controlled application of an axial load. This test
method provides an approximate value of the strength of cohesive materials in terms of total
stresses. The undrained shear strength of a cohesive soil sample is typically one-half (1/2) the
unconfined compressive strength.
Water (Moisture) Content of Soil by Mass (ASTM D 2216)
This test method determines water (moisture) content by mass of soil where the reduction in
mass by drying is due to loss of water. The water (moisture) content of soil, expressed as a
percentage, is defined as the ratio of the mass of water to the mass of soil solids. Moisture
content may provide an indication of cohesive soil shear strength and compressibility when
compared to Atterberg Limits.
Liquid Limit, Plastic Limit and Plasticity Index of Soils (ASTM D 4318)
This test method determines the liquid limit, plastic limit and the plasticity index of soils. These
tests, also known as Atterberg limits, are used from soil classification purposes. They also
provide an indication of the volume change potential of a soil when considered in conjunction
with the natural moisture content. The liquid limit and plastic limit establish boundaries of
consistency for plastic soils. The plasticity index is the difference between the liquid limit and
plastic limit.
TWE Project No. 16.53.076 4-2 Report No. 13604
Dry Unit Weight of Soils
This test method determines the weight per unit volume of soil, excluding water. Dry unit
weight is used to relate the compactness of soils to volume change and stress-strain tendencies of
soils when subjected to external loadings.
Soil properties including moisture content, dry unit weight, Atterberg Limits, grain size
distribution, penetration resistance, and compressive strength are presented on the project boring
logs in Appendix B.
TWE Project No. 16.53.076 5-1 Report No. 13604
5 SITE AND SUBSURFACE CONDITIONS
5.1 General
Our interpretations of soil and groundwater conditions within the project site are based on
information obtained at the soil boring locations only. This information has been used as the
basis for our conclusions and recommendations included in this report. Subsurface conditions
may vary at areas not explored by the soil borings. Significant variations at areas not explored by
the soil borings will require reassessment of our recommendations.
5.2 Site Description and Surface Conditions
The site is an approximate 2-acre tract of land located south of South Padre Island Dr. (TX HWY
358, SPID) frontage road near Airline Rd., in Corpus Christi, Texas. The vacant property is
specifically located behind several existing businesses which can be accessed from the frontage
road. The site is also accessible by utilizing a connector street which runs between Williams Dr.,
and SPID frontage road. At the time of our field investigation, the site was covered by native
vegetation (grass and weeds), with overgrown brush and trees towards the southern area of the
property. Topographic survey information provided by the client for the site indicated an
approximate change in elevation of about 1 to 1.5-ft. in the proposed location of the building
foundation. The site was observed to be at a higher elevation along its east boundary and
decreased in elevation towards the north, west, and south boundaries. Poor drainage was
exhibited on the north side of the property.
5.3 Subsurface Conditions
The soil profile encountered in the project borings consisted mostly of cohesive soils, with a
clayey sand stratum in boring B-2. Sandy Fat Clay (CH), Fat Clay with Sand (CH), Lean Clay
with Sand (CL), Fat Clay (CH), and Sandy Lean Clay (CL) soils were encountered from existing
grade to termination depths of 25-ft. and 50-ft. below existing grade. The Clayey Sand (SC)
stratum was present below about 10-ft. and extended to about 14.5-ft. in Boring B-2. The
consistency of the clay soils was typically stiff to hard, but soft between about 13-ft and 16-ft in
boring B-1. The relative density of the clayey sand stratum ranged from medium dense to very
dense. Detailed descriptions of the soils encountered at the boring locations are presented on the
boring logs in Appendix B.
5.4 Subsurface Soil Properties
Results of Atterberg Limit tests on selected cohesive soil samples from the project borings
indicated liquid limits (LL) ranging from 30 to 80 with corresponding plasticity indices (PI)
ranging between 15 to 64. In-situ moisture contents of the soils ranged from 14% to 29%. The
amount of material passing the No. 200 sieve ranged from 54% to 90% within the selected
cohesive samples tested for grain size distribution.
Undrained shear strengths derived from field pocket penetrometer readings ranged from 0.50-tsf.
to 4.50+-tsf. Undrained shear strengths derived from laboratory unconfined compressive (UC)
strength testing ranged from 0.47-tsf. to 2.84-tsf., with corresponding dry unit weights ranging
TWE Project No. 16.53.076 5-2 Report No. 13604
from 95-pcf. to 105-pcf. Shear strengths of cohesive soils inferred from SPT blow counts varied
from soft to stiff.
The results of Atterberg Limit tests performed on the selected semi-cohesionless samples (clayey
sand) from Boring B-2 indicated a liquid limit of 38 with a corresponding PI of 26. In-situ
moisture content and percent finer than No. 200 sieve tests for the clayey sands ranged from 20%
to 24% and 39% to 47%, respectively.
Tabulated laboratory test results at the recovered sample depths are presented on the boring logs
in Appendix B.
5.5 Groundwater Observations
Groundwater measurements were attempted in the project borings during dry-auger drilling.
Groundwater level measurements are shown in Table 5-1 below.
Table 5-1:
Groundwater Level Measurements
Boring
No.
Boring
Depth
(feet)
Groundwater Level Depth
Encountered
During Drilling
(feet)
Observed in the Open Borehole after 10 to 15
minutes (feet)
B-1 50’ 15’ 11’-6”
B-2 25’ 13’ 9’-6”
Groundwater levels may fluctuate with climatic and seasonal variations and should be verified
before construction. Accurate determination of the static groundwater level is typically made with a
standpipe piezometer. Installation of a piezometer to evaluate the long-term groundwater condition
was not included within the current scope of services.
TWE Project No. 16.53.076 5-3 Report No. 13604
5.6 Shrink / Swell Potential
The tendency for a soil to shrink and swell with change in moisture content is a function of clay
content and type which are generally reflected in soil consistency as defined by Atterberg Limits. A
generalized relationship between shrink/swell potential and soil plasticity index (PI) is shown in
Table 5-2 below.
Table 5-2:
General Relationship Between PI and Shrink/Swell Potential
P.I. Range Shrink/Swell Potential
0 – 15 Low
15 – 25 Medium
25 – 35 High
> 35 Very High
The amount of expansion that will actually occur with increase in moisture content is inversely
related to the overburden pressure. Therefore, the larger the overburden pressure, the smaller the
amount of expansion. Near-surface soils are thus most susceptible to shrink/swell behavior because
they experience low amounts of overburden. Overall, the cohesive soils at this site possess high to
very high shrink/swell potential.
TWE Project No. 16.53.076 6-1 Report No. 13604
6 FOUNDATION RECOMMENDATIONS
6.1 Discussion
The soils above a depth of about 12-ft at this site are plastic sandy fat clays and fat clays with
sand, which can experience significant shrink/swell movements with change in moisture content.
Based on the expansive nature of the shallow clay soils and the anticipated column loads for the
structure, a foundation system that is capable of transferring column loads to below the zone of
seasonal moisture change is needed for the project. A foundation system such as drilled and
underreamed piers can be used for this purpose. Recommendations for design and construction
of drilled and underreamed piers are provided below.
6.2 Drilled and Underreamed Piers
Drilled and underreamed piers can be used for support of the proposed hotel at the site. Design
and construction recommendations pertaining to drilled and underreamed piers are provided in
the following report sections.
6.2.1 Pier Depth
Drilled and underreamed piers should be founded at a depth of about 24-ft. below the top of the
building pad within the natural clay soils. At this depth, the piers should be founded below any
water bearing strata as well as the weaker soils in the range of about 13-ft to 16-ft in boring B-1.
We recommend that drilled and underreamed piers have a minimum shaft diameter of 18-in. to
facilitate inspection of the excavation and reinforcement placement.
We recommend the ratio of underream to shaft diameter be no greater than 3. The angle of
underreamed bells to horizontal should not be less than 45° to avoid potential collapse of the
bells. In the event of borehole sloughing or caving at the time of bell drilling, a larger angle of
60° should be used. If stable excavation of bells cannot be completed because local anomalies
are encountered or sloughing and caving occurs, TWE should be contacted to investigate the
problem and modify our recommendations accordingly.
6.2.2 Allowable Bearing Pressures
Drilled and underreamed piers founded on undisturbed natural soils at a depth of about 24-ft.
below the top of building pad can be designed using a net allowable bearing pressure of 6,000
pounds per square foot (psf) for dead plus sustained live load or 9,500-psf for total load
conditions, whichever condition governs. These net allowable bearing pressure values contain a
factor of safety of 3.0 and 2.0 against bearing capacity failure, respectively. The clear spacing
between underreamed piers should be a minimum of one (1) underream diameter to avoid
influence of adjacent footings.
TWE Project No. 16.53.076 6-2 Report No. 13604
6.2.3 Settlement
Settlement of properly constructed drilled and underreamed piers bearing on natural soils at a
depth of about 24-ft. below the top of the building pad, and designed using the allowable bearing
pressures presented above, should be less than 1-in. Drilled piers should have a clear spacing of
one (1) underream diameter of the larger adjacent underream. Differential settlements between
drilled piers will be governed by variation in subsurface conditions, structural loading conditions,
and quality of the pier construction such as cleanliness of the underream.
6.2.4 Uplift Load Due to Swell Pressure
Swell pressure induced uplift loads acting on drilled piers can be estimated using a unit uplift
skin friction (fs) in pounds per square foot (psf) acting on the outer perimeter of the shaft from
the bottom of the structural select fill building pad, if present, to a depth of about 12-ft below top
of the building pad. The estimated uplift skin friction derived from the subsurface conditions
encountered in the project boring can be taken as 800-psf. The piers should be adequately
reinforced to resist the tensile loads without inducing any distress to the structure or piers.
6.2.5 Uplift Resistance
The allowable uplift capacity of drilled and underreamed piers within the project site could be
calculated using the following equations:
For Df/B > 1.5
Qa = Wf/1.2 + [8.1(B2 – b
2)/FS]
For Df/B < 1.5
Qa = Wf/1.2 + [3.5(Df/B)2(B
2 – b
2)/FS]
where:
Qa = Allowable Uplift Capacity (kips)
Wf = Weight of Footing (kips)
Df = Depth of Base of Footing below Ground Surface (ft)
B = Diameter of Underream (ft)
b = Diameter of Shaft (ft)
FS = Factor of Safety (2.0 for transient loads, 3.0 for sustained loads)
It is recommended that a total unit weight of 150-pcf be used for concrete to calculate the weight
of the footing. The weight of the footing should be reduced by a factor of safety of 1.2.
TWE Project No. 16.53.076 6-3 Report No. 13604
6.2.6 Underreamed Pier Construction
The following items will be important to the successful completion of drilled and underreamed
piers.
All pier excavations should be observed by TWE to determine when the proper bearing
stratum is encountered and to record other observations regarding pier excavations. Pier
excavations should be checked for size and depth prior to the placement of steel and
concrete. Precautions should be taken during the placement of the pier reinforcement
and concrete to prevent loose excavated material from falling into the excavation.
Drilled piers should be installed in accordance with the Manual on Drilled Shafts:
Construction Procedures and Design Methods, [U.S. Department of Transportation-
Federal Highway Administration (Pub. No. FHWA-IF-99-025) and ADSC: The
International Association of Foundation Drilling Contractors (Pub. No. ADSC-TL-4),
August 1999] by Lymon, C. Reese and Michael W. O'Neill.
To minimize the length of time the soils are left unsupported and exposed to the
elements, we recommend that structural pier concrete be on site and prepared for
placement prior to belling (underreaming). Reinforcing steel and concrete should be
placed immediately after acceptance of the underream. This should help to reduce the
possibility of sloughing/caving and/or intrusion of groundwater into open excavations by
minimizing the time the bell remains open without concrete
Based on the subsurface conditions and the depth of the static groundwater level
encountered in the borings, sandy semi-cohesive soils with groundwater are anticipated
to be encountered in drilled pier excavations. We anticipate the use of temporary steel
casing or other appropriate measures to facilitate proper drilled pier installation.
Temporary casing should be sealed in the clay soils below the water bearing clayey
sands. A positive head of plastic concrete must be maintained above the static
groundwater level during extraction of the casing.
Reinforcement steel cages placed in pier shafts should be designed to be stable during
the placement of concrete. Prompt placement of concrete in excavations as they are
completed, cleaned and inspected is strongly recommended to limit deterioration of the
bearing stratum. Under no circumstances should a pier be drilled that cannot be filled
with concrete before the end of the working day.
6.3 Grade Beams
Grade beams spanning between drilled piers should be structurally suspended above the
subgrade. A minimum 8-in void space should be provided between the bottom of the grade
beams and the top of the subgrade. Cardboard carton forms are commonly used for this purpose.
The sides of excavations should be protected from sloughing, thus, filling the void space.
TWE Project No. 16.53.076 6-4 Report No. 13604
6.4 Lightly Loaded Interior Floor Slabs
Surface and near surface soils encountered in the project borings for this site possess high
shrink/swell potential with changes in moisture content. Based on the results of our field and
laboratory programs, the Potential Vertical Rise (PVR) for the existing subsurface soil profile at
this site, as determined by Test Method TEX-124-E is calculated to be about 5.0 to 5.5-in for
”dry” moisture conditions. It is generally accepted that a primary source of foundation distress in
the Coastal Bend is soil movements associated with shrink/swell behavior of the underlying
supporting soils. It is therefore recommended that measures be taken to reduce potential
shrink/swell movements below ground supported floor slabs for the proposed building.
Typically, potential movements below lightly loaded interior floors are reduced to the order of
one (1)-in or less, although in some instances movements of more than one (1)-in are acceptable.
The most positive means of reducing potential floor slab movement at this site is the use of a
structurally suspended floor system. The floor slab is structurally suspended above the subgrade
with a minimum crawl space of 8-in. Loads from the floor slab are carried to grade beams which
transfer the loads to columns and the drilled pier foundation. The crawl space subgrade should
be shaped and graded to avoid ponding of water on its surface. Water should be drained to the
perimeter of the crawl space and carried well away from the building prior to discharging.
As an alternate, floor slabs for the proposed building may also consist of ground-supported units
provided that potential shrink/swell movements are reduced to tolerable levels. A typical method
of reducing the swell potential includes removal of a portion of the existing clay soils and
installation of non-expansive structural fill beneath the floor slab. The amount of removal and
replacement needed is dependent upon the amount of shrink/swell movement that the foundation
and/or superstructure can tolerate and determined by the structural engineer.
It is our understanding that the finished floor elevation (FFE) will be approximately 2.5-ft. above
existing grade. TWE recommends that non-expansive structural fill material be utilized to bring
the existing grade up to FFE. Utilizing this information, a summary of PVR values with
corresponding excavation and replacement material amounts for “dry” moisture conditions are
provided in Table 6-1 below. This method has beneficial results but does not totally eliminate
the potential for shrink/swell movements.
Table 6-1:
Material Excavation and Replacement with Resulting PVR
Amount of Excavation
(feet)
Amount of Replacement
(feet) Resulting PVR (in.)
0 2 4.0 to 4.5
2 4 2.75 to 3.25
4 6 2.0 to 2.5
6 8 1.5 to 1.75
8 10 1.0 to 1.25
TWE Project No. 16.53.076 6-5 Report No. 13604
Based on these results, we recommend that site preparation include:
Removal of the existing soils to the specified depth listed above in Table 6-1 for the
allowable PVR determined by the structural engineer.
After achieving specified subgrade elevation, proof-roll exposed subgrade and compact as
indicated below.
After testing and acceptance of subgrade, immediate placement and compaction of non-
expansive structural select fill as listed in Table 6-1, within the footprint of the proposed
new building as indicated below.
Maintain moisture in select fill pad until the concrete floor slab is constructed.
The subgrade to receive non-expansive structural fill should be proof-rolled as indicated below in
Section 7.1. After proof-rolling, the subgrade should be scarified to a depth of 8-in, moisture
adjusted to above (0 to +4%) optimum moisture content, and compacted to at least 95% of
maximum dry density determined by ASTM D 698. After testing is accepted, the first lift of
structural fill should be immediately placed and compacted.
Material and compaction requirements for non-expansive structural fill are provided below in
Section 7.1 of this report. It is recommended that select fill be used for elevation of the building
pad above existing grade at least 12 inches to provide positive drainage away from the building.
It should be noted that these methods for reducing shrink/swell movements are designed for
normal seasonal changes in soil moisture content of the subgrade soils. Excessive shrink/swell
movements can be expected if increases in soil moisture content occur as a result of broken water
and sewer lines, improper drainage of surface water, shrubbery and trees planted near the
foundation slab and excessive lawn or shrubbery irrigation. Gutter and downspouts should be
provided and runoff should be carried away from the building before discharging unto flatwork
or paving.
Due to the expansive nature of the subgrade soils at this site, special care should be taken not to
allow the exposed subgrade soils to become extremely wet or extremely dry of the existing
moisture content. Therefore, delays between excavation and fill placement should be avoided. If
construction occurs during rainy weather and the exposed subgrade soils are allowed to become
wet or saturated, removal and replacement of excessively soft, wet soils or lime-stabilization
should be anticipated. The depth of undercutting should be determined in the field by TWE.
It is recommended that a vapor barrier such as polyethylene sheeting be provided beneath the soil
supported floor slab. Adequate construction joints and reinforcement should be provided to
reduce the potential for cracking of the floor slab due to differential movement and volume
change in concrete. Crawl spaces below suspended floor systems should be thoroughly
ventilated to reduce potential for moisture to be trapped below floors.
TWE Project No. 16.53.076 7-1 Report No. 13604
7 EARTHWORK CONSIDERATIONS
7.1 Subgrade Preparation and Structural Select Fill
Any subgrade to receive fill soils or pavements should be proof rolled with at least a 20-ton
pneumatic roller, loaded dump truck, or equivalent, to detect weak areas. Such weak areas
should be removed and replaced with soils exhibiting similar classification, moisture content,
and density as the adjacent in-place soils. Subsequent to proof rolling, and just prior to
placement of select fill, the exposed subgrade should be compacted to at least 95% of the
maximum dry density at a moisture above (0 to +4%) the optimum moisture in accordance with
Standard Proctor (ASTM D 698) procedures.
Proper site drainage should be maintained during construction so that ponding of surface runoff
does not occur and cause construction delays and/or inhibit site access. Due to the nature of the
subgrade, the cohesive soils can become wet and soft. If the subgrade becomes wet and soft,
consideration can be given to removal or replacement of the wet material with structural fill
material.
The maximum loose thickness for each lift will depend on the type of compaction equipment
used. Recommended fill layers are summarized in Table 7-1 below.
Table 7-1: Compaction Equipment and Maximum Lift Thickness
Compaction Equipment Maximum Lift Thickness
Mechanical Hand Tamper 4.0-in
Pneumatic Tired Roller 6.0-in
Tamping Foot Roller 8.0-in
Sheepsfoot Roller 8.0-in
Non-expansive structural fill for this project should consist of a clean low-plasticity sandy clay (CL)
or clayey sand (SC) material with a liquid limit of less than 40 and a plasticity index between 7 and
20. The select fill should be placed in thin lifts, not exceeding 8-in loose measure, moisture
conditioned to between -2% and +3% of optimum moisture content, and compacted to a minimum
95% of the maximum dry density as determined by ASTM D 698 (Standard Proctor).
Prior to any filling operations, samples of the proposed borrow materials should be obtained for soil
classification and laboratory moisture-density testing. The tests will provide a basis for evaluation
of fill compaction by in-place density testing. A qualified soil technician should perform sufficient
in-place density tests during the earthwork operations to verify that proper levels of compaction are
being attained.
TWE Project No. 16.53.076 7-2 Report No. 13604
7.2 Drainage
The performance of the foundation system for the proposed building and site pavement will not
only be dependent upon the quality of construction but also upon the stability of the moisture
content of the near surface soils. Therefore, we highly recommend that site drainage be developed
so that ponding of surface runoff near the building or pavement does not occur. Accumulations of
water near the structure foundation or pavement could cause significant moisture variations in the
soils adjacent to the foundation and pavement thus increasing the potential for structural distress.
TWE Project No. 16.53.076 8-1 Report No. 13604
8 PAVEMENT DESIGN RECOMMENDATIONS
8.1 New Pavement Sections
It is our understanding that a rigid pavement system is preferred for proposed driveways and
parking areas associated with this project. Since detailed traffic loads and frequencies were not
available at the time of this report, we have assumed traffic frequencies and loading for similar
projects that have been completed in the past. The assumed traffic frequencies and loads used to
design pavement sections for this project are presented in Table 8-1 below.
Table 8-1: Vehicle Classification and Traffic Loading
Pavement Area Traffic Design Index Description
Light-Duty
Pavements DI-1
Designed using traffic conditions of 20,000 18-kip
equivalent single axle loads (ESALs).
Heavy-Duty
Pavements DI-2
Designed using traffic conditions of 120,000 18-
kip equivalent single axle loads (ESALs).
Based on the estimated traffic conditions and methods found in the AASHTO, Guide for Design of
Pavement Structures, design recommendations for rigid pavement sections using a 20 year design
life are provided in the following sections of this report. The DI-2 pavement sections provided
should be used for routes used by delivery and waste disposal trucks. A reinforced concrete pad
should be placed at the location so that the waste disposal truck’s loading end tires rest on the pad
during waste bin unloading. The traffic conditions presented above should be verified by the civil
design engineer. TWE should be contacted for possible further recommendations if actual traffic
conditions vary from those presented above.
8.1.1 Rigid Pavement Design
The primary design requirements needed for rigid pavement design according to the AASHTO
Guide include the following:
28-day Concrete Modulus of Rupture, psi;
28-day Concrete Elastic Modulus, psi;
Effective Modulus of Subgrade Reaction, pci (k-value);
Serviceability Indices;
Load Transfer Coefficient;
Drainage Coefficient;
Overall Standard Deviation;
Reliability, %; and,
Design Traffic, 18-kip Equivalent Single Axle Load (ESAL)
In our analysis, we assumed U.S. climatic region I (wet and no freeze characteristics), the values
used for our analyses are presented in Table 8-2 on the following page.
TWE Project No. 16.53.076 8-2 Report No. 13604
Table 8-2: Rigid Pavement Design Values
Description Value
28-day Concrete Modulus of Rupture (Mr) 620-psi
28-day Concrete Elastic Modulus 5,000,000-psi
Effective Modulus of Subgrade Reaction 50-pci
Serviceability Indices Initial 4.5
Terminal 2.5
Load Transfer Coefficient 3.2
Drainage Coefficient 1.0
Overall Standard Deviation 0.39
Reliability 80
Design Traffic, 18-kip Equivalent Single Axle Load (ESAL) – Light-Duty Pavement (DI-1) 20,000
Design Traffic, 18-kip Equivalent Single Axle Load (ESAL) – Heavy-Duty Pavement (DI-2) 120,000
Table 8-3 below, provides the recommended minimum typical pavement section derived from
our analysis using the AASHTO Pavement Design Guide.
Table 8-3: Recommended Minimum Typical Rigid Pavement Thicknesses
Traffic Design Index RC LSS CS
DI-1
Option A 5.0-in. 8.0-in. ---
Option B 6.0-in. --- 8.0-in.
DI-2
Option A 7.0-in. 8.0-in. ---
Option B 8.0-in. --- 8.0-in.
RC = Reinforced Portland Cement Concrete
LSS = Lime Stabilized Subgrade
CS = Compacted Subgrade
Reinforcing steel consisting of deformed steel rebar should be used in concrete pavement.
Thickness is based on concrete flexural strength, soil modulus and traffic volume. Selection of
steel is dependent on joint spacing, slab thickness and other factors as discussed in Portland Cement
Association publications. The following suggested guidelines for the concrete pavement should be
modified by the civil-structural engineer based upon the actual configuration of the pavement layout
and published Portland Cement Association and ACI articles. Table 8-4 on the following page
presents these guidelines.
TWE Project No. 16.53.076 8-3 Report No. 13604
Table 8-4: Rigid Pavement Components
Component Description
Minimum Reinforcing Steel #3 bars should be spaced at 18-in on centers in both directions.
Minimum Dowel Size 3/4-in bars, 18-in in length, with one (1) end treated to slip
should be spaced at 12-in on centers at each joint.
Control Joint Spacing
Maximum control joint spacing should be 15-ft. If sawcut,
control joints should be cut as soon as the concrete has hardened
sufficiently to permit sawing without excessive raveling which is
usually within four (4) to twenty-four (24) hours of concrete
placement.
Isolation / Expansion Joints Expansion joints should be used in areas adjacent to structures,
such as manholes and walls.
8.2 Pavement Section Materials
Reinforced Concrete (RC)
RC should be provided in accordance with TxDOT Item 421 “Hydraulic Cement Concrete”,
2004. Concrete should be designed to meet a minimum average flexural strength (modulus of
rupture) of at least 620-psi at 28-days or a minimum average compressive strength of 4,500-psi at
28-days. Reinforcing steel consisting of deformed steel rebar should be used in accordance with
TxDOT Item 440 “Reinforcing Steel.”
The first few loads of concrete should be checked for slump, air and temperature on start-up
production days to check for concrete conformance and consistency. Concrete should be
sampled and strength test specimens [two (2) specimens per test] prepared on the initial day of
production and for each 400-yd2 or fraction thereof of concrete pavement thereafter. At least one
(1) set of strength test specimens should be prepared for each production day. Slump, air and
temperature tests should be performed each time strength test specimens are made. Concrete
temperature should also be monitored to ensure that concrete is consistently within the
temperature requirements.
Lime Stabilized Subgrade
Lime stabilization of the subgrade soils can be considered for the pavement sections included in
Table 8-3 above. Proper preparation and lime stabilization of the pavement subgrade will
improve long-term pavement performance by reducing plasticity of the clay soils, increasing their
load carrying capacity, and improving their workability.
After completion of necessary stripping and clearing, the exposed soil subgrade should be
carefully evaluated by probing and testing. Any unsuitable material (shell, gravel, organic
material, wet, soft or loose soil) still in place should be removed. The exposed soil subgrade
should be further evaluated by proofrolling with a heavy pneumatic tired roller, loaded dump
TWE Project No. 16.53.076 8-4 Report No. 13604
truck or similar equipment weighing at least 20-tons to ensure that soft or loose material does not
exist beneath the exposed soils. Proofrolling procedures should be observed routinely by a
qualified representative of TWE. Any undesirable material revealed should be removed and
replaced in a controlled manner with soils similar in classification or select fill. If lime
stabilization is not used, the subgrade should be compacted as indicated below.
Once final subgrade elevation is achieved and prior to placement of reinforced concrete wearing
surface, the exposed surface of the pavement subgrade soil should be scarified to a depth of 8-in
and mixed with hydrated lime in conformance with TxDOT Item 260 “Lime Treatment (Road-
Mixed)”. It is estimated that 7% hydrated lime by dry unit weight of soil will be required.
Assuming an in-place unit weight of 120-pcf for the roadway subgrade soils, 7% lime by dry unit
weight equates to about 50-lbs of lime per square yard of treated subgrade. The actual quantity
of lime required should be determined after the pavement area is stripped and subgrade soils are
exposed by use of a laboratory soil treatability study. Lime used during chemical stabilization
should be Type A hydrated lime or Type B commercial slurry. The lime stabilized subgrade
should be compacted to a minimum 95% of the maximum dry density as determined by ASTM D
698 at a moisture content within the range of 4% above optimum.
Lime stabilization should extend at least 1-ft beyond the pavement edge to reduce effects of
seasonal shrinking and swelling. In areas where hydrated lime is used for stabilization, routine
sampling and Atterberg limit tests should be performed to verify the resulting plasticity index of
the stabilized mixture is at/or below 20.
Mechanical lime stabilization of the pavement subgrade will not prevent normal seasonal
movement of the underlying untreated materials. Therefore, good perimeter surface drainage
with a minimum 2% slope away from the pavement is recommended.
8.3 Pavement Drainage and Maintenance
Providing drainage away from the pavement and maintaining the pavement to prevent infiltration
of water into the subgrade soils is essential. Water ponding adjacent to the pavement will
infiltrate the subgrade and result in high maintenance costs and premature pavement failure and,
therefore, should be avoided. Periodic maintenance should be performed on the pavement
sections to seal any surface cracks and prevent infiltration of water into the subgrade.
TWE Project No. 16.53.076 9-1 Report No. 13604
9 LIMITATIONS AND DESIGN REVIEW
9.1 Limitations
This report has been prepared for the exclusive use of Kantibhai Bhakta and the project team for
specific application to the design and construction of the proposed new 4-story hotel in Corpus
Christi, Texas. Our report has been prepared in accordance with the generally accepted
geotechnical engineering practice common to the local area. No other warranty, express or
implied, is made.
The analyses and recommendations contained in this report are based on the data obtained from
the referenced subsurface explorations within the project site. The soil borings indicate
subsurface conditions only at the specific location, time and depth penetrated. The soil borings
do not necessarily reflect strata variations that could exist at other locations within the project
site. The validity of our recommendations is based in part on assumptions about the stratigraphy
made by the Geotechnical Engineer. Such assumptions may be confirmed only during
construction and installation of the project structures. Our recommendations presented in this
report must be reevaluated if subsurface conditions during the construction phase are different
from those described in this report.
If any changes in the nature, design or location of the project are planned, the conclusions and
recommendations contained in this report should not be considered valid unless the changes are
reviewed and the conclusions modified or verified in writing by TWE. TWE is not responsible
for any claims, damages or liability associated with interpretation or reuse of the subsurface data
or engineering analyses without the expressed written authorization of TWE.
9.2 Design Review
Review of the design and construction drawings as well as the specifications should be
performed by TWE before release. The review is aimed at determining if the geotechnical design
and construction recommendations contained in this report have been properly interpreted.
Design review is not within the authorized scope of work for this study.
9.3 Construction Monitoring
Construction surveillance is recommended and has been assumed in preparing our
recommendations. These field services are required to check for changes in conditions that may
result in modifications to our recommendations. The quality of the construction practices will
affect foundation performance and should be monitored. TWE would be pleased to provide
construction monitoring, testing and inspection services for the project.
9.4 Closing Remarks
We appreciate the opportunity to be of service during this phase of the project and we look
forward to continuing our services during the construction phase and on future projects.
TWE Project No. 16.53.076 Report No. 13604
APPENDIX A
SOIL BORING LOCATION PLAN
TWE DRAWING NO. 16.53.076-1
COPYRIGHT © 2015 GOOGLE MAP. ALL RIGHTS RESERVED.
B-2
COPYRIGHT © 2015 GOOGLE MAP. ALL RIGHTS RESERVED.
B-1
Sheet: 1
File: C:\Users\ecrochet\Desktop\Desktop_Folder\CAD\CAD\XREF\TWE_Logo.pdf
Missing or invalid reference
R S S Architects L.L.C. Drawing # A-201
TWE Project No. 16.53.076 Report No. 13604
APPENDIX B
LOGS OF PROJECT BORINGS AND A KEY TO
TERMS AND SYMBOLS USED ON BORING LOGS
0
5
10
15
20
25
30
35
Stiff to hard dark gray SANDY FAT CLAY (CH) withtrace organics
-color changes to dark brown with calcareous nodules
-with gypsum crystals and ferrous stains
-color changes to light brown
-with sand seams and partings, becomes soft below13.5-ft.
Stiff to hard light brown FAT CLAY with SAND (CH),gypsum crystals, and ferrous stains
-with sand seams
-with gypsum crystals and calcareous nodules
Stiff to very stiff tan and gray FAT CLAY (CH)
-with calcareous nodules and ferrous stains
(P) 4.50+
(P) 4.50+
(P) 1.50
(P) 1.25
(P) 0.50
(P) 4.50+
(P) 2.75
(P) 3.50
3/6"5/6"5/6"
2/6"1/6"2/6"
5/6"6/6"7/6"
14
23
23
25
29
21
106
100
102
104
64
59
55
51
47
38
1.40
1.49
1.49
5
14
6
63
70
75
54
73
90
TOLUNAY-WONG ENGINEERS, INC.
LOG OF BORING B-1PROJECT: Proposed Hotel
Corpus Christi, TexasCLIENT: Mccor Hospitality
COMPLETION DEPTH: 50 ft REMARKS: Groundwater was encountered at a depth of 15-ft. during drilling operations.After a 15-min. waiting period, water level was at a depth of 11'-6" belowexisting grade. At the completion of drilling, the open borehole was backfilledwith soil cuttings.
DATE BORING STARTED: 11/23/2016DATE BORING COMPLETED: 11/23/2016LOGGER: J. DesaiPROJECT NO.: 16.53.076
Page of1
DE
PT
H (
ft)
SA
MP
LE
TY
PE
SY
MB
OL/U
SC
S
MATERIAL DESCRIPTION
COORDINATES: N 27° 42' 08.20"W 97° 21' 53.40"
SURFACE ELEVATION: --DRILLING METHOD:
Dry Augered: 0-ft. to 50-ft.Wash Bored: -- to --
(P)
PO
CK
ET
PE
N (
tsf)
(T)
TO
RV
AN
E (
psf)
ST
D. P
EN
ET
RA
TIO
N
TE
ST
(blo
ws/ft)
MO
IST
UR
E
CO
NT
EN
T (
%)
DR
Y U
NIT
WE
IGH
T
(pcf)
LIQ
UID
LIM
IT
(%)
PLA
ST
ICIT
Y
IND
EX
(%
)
CO
MP
RE
SS
IVE
ST
RE
NG
TH
(ts
f)
FA
ILU
RE
ST
RA
IN (
%)
CO
NF
ININ
G
PR
ES
SU
RE
(psi)
PA
SS
ING
#200
SIE
VE
(%
)
OT
HE
R T
ES
TS
PE
RF
OR
ME
D
2
35
40
45
50
55
60
65
70
Stiff to very stiff tan and gray FAT CLAY (CH),slickensided with calcareous nodules and ferrous stains
Firm tan and gray SANDY LEAN CLAY (CL)
Bottom @ 50'
(P) 1.50
(P) 3.75
(P) 3.25
26
20
98
108 30 15
2.84
0.47
11
4
87
69
TOLUNAY-WONG ENGINEERS, INC.
LOG OF BORING B-1PROJECT: Proposed Hotel
Corpus Christi, TexasCLIENT: Mccor Hospitality
COMPLETION DEPTH: 50 ft REMARKS: Groundwater was encountered at a depth of 15-ft. during drilling operations.After a 15-min. waiting period, water level was at a depth of 11'-6" belowexisting grade. At the completion of drilling, the open borehole was backfilledwith soil cuttings.
DATE BORING STARTED: 11/23/2016DATE BORING COMPLETED: 11/23/2016LOGGER: J. DesaiPROJECT NO.: 16.53.076
Page of2
DE
PT
H (
ft)
SA
MP
LE
TY
PE
SY
MB
OL/U
SC
S
MATERIAL DESCRIPTION
COORDINATES: N 27° 42' 08.20"W 97° 21' 53.40"
SURFACE ELEVATION: --DRILLING METHOD:
Dry Augered: 0-ft. to 50-ft.Wash Bored: -- to --
(P)
PO
CK
ET
PE
N (
tsf)
(T)
TO
RV
AN
E (
psf)
ST
D. P
EN
ET
RA
TIO
N
TE
ST
(blo
ws/ft)
MO
IST
UR
E
CO
NT
EN
T (
%)
DR
Y U
NIT
WE
IGH
T
(pcf)
LIQ
UID
LIM
IT
(%)
PLA
ST
ICIT
Y
IND
EX
(%
)
CO
MP
RE
SS
IVE
ST
RE
NG
TH
(ts
f)
FA
ILU
RE
ST
RA
IN (
%)
CO
NF
ININ
G
PR
ES
SU
RE
(psi)
PA
SS
ING
#200
SIE
VE
(%
)
OT
HE
R T
ES
TS
PE
RF
OR
ME
D
2
0
5
10
15
20
25
30
35
Stiff to hard dark gray and brown FAT CLAY with SAND(CH), trace organics
-color changes to gray and brown
-color changes to brown
-color changes to brown and light brown, with gypsumcrystals and ferrous stains
-color changes to light brown and gray, becomesslickensided
Medium dense to very dense light brown and grayCLAYEY SAND (SC)
-color changes to brown and gray
Very stiff to hard brown and gray LEAN CLAY withSAND (CL), trace calcareous nodules
-color changes to gray with sand seams
-color changes to brown and gray
Bottom @ 25'
(P) 4.50
(P) 2.50
(P) 1.50
(P) 2.00
(P) 1.50
(P) 0.50
(P) 4.50+
(P) 3.75
2/6"50/6"
20
28
28
20
24
19
96
95
96
107
108
69
80
38
44
50
64
26
29
1.18
1.56
2.64
8
15
9
67
73
82
47
39
74
TOLUNAY-WONG ENGINEERS, INC.
LOG OF BORING B-2PROJECT: Proposed Hotel
Corpus Christi, TexasCLIENT: Mccor Hospitality
COMPLETION DEPTH: 25 ft REMARKS: Groundwater was encountered at a depth of 13-ft. during drilling operations.After a 15-min. waiting period, water level was at a depth of 9'-6" belowexisting grade. At the completion of drilling, the open borehole was backfilledwith soil cuttings.
DATE BORING STARTED: 11/23/2016DATE BORING COMPLETED: 11/23/2016LOGGER: J. DesaiPROJECT NO.: 16.53.076
Page of1
DE
PT
H (
ft)
SA
MP
LE
TY
PE
SY
MB
OL/U
SC
S
MATERIAL DESCRIPTION
COORDINATES: N 27° 42' 09.94"W 97° 21' 52.69"
SURFACE ELEVATION: --DRILLING METHOD:
Dry Augered: 0-ft. to 25-ft.Wash Bored: -- to --
(P)
PO
CK
ET
PE
N (
tsf)
(T)
TO
RV
AN
E (
psf)
ST
D. P
EN
ET
RA
TIO
N
TE
ST
(blo
ws/ft)
MO
IST
UR
E
CO
NT
EN
T (
%)
DR
Y U
NIT
WE
IGH
T
(pcf)
LIQ
UID
LIM
IT
(%)
PLA
ST
ICIT
Y
IND
EX
(%
)
CO
MP
RE
SS
IVE
ST
RE
NG
TH
(ts
f)
FA
ILU
RE
ST
RA
IN (
%)
CO
NF
ININ
G
PR
ES
SU
RE
(psi)
PA
SS
ING
#200
SIE
VE
(%
)
OT
HE
R T
ES
TS
PE
RF
OR
ME
D
1