geotechnical engineering study new astromatic car...
TRANSCRIPT
GEOTECHNICAL ENGINEERING STUDY
NEW ASTROMATIC CAR WASH
CORPUS CHRISTI, TEXAS
Prepared for:
Astromatic Car Wash, LP
P.O. Box 128
Alice, Texas 78333
Prepared by:
Tolunay-Wong Engineers, Inc.
826 South Padre Island Drive
Corpus Christi, Texas 78416
January 24, 2017
Project No. 16.53.084 / Report No. 13950
TWE Project No. 16.53.084 i Report No. 13950
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 CONDITIONS 5-1
5.1 General 5-1
5.2 Site Description 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 5-2
6 GEOTECHNICAL RECOMMENDATIONS 6-1
6.1 Discussion 6-1
6.2 Stiffened, Conventionally Reinforced, Waffle-Type Beam and Slab-on-Grade
Foundation System 6-1
6.3 Uplift Resistance 6-4
6.4 Lateral Resistance 6-4
6.5 Settlement 6-4
6.6 Shallow Foundation Construction 6-5
7 EARTHWORK CONSIDERATIONS 7-6
7.1 Subgrade Preparation and Structural Select Fill 7-6
7.2 Drainage 7-7
8 PAVEMENT DESIGN RECOMMENDATIONS 8-1
8.1 Pavement Design Criteria 8-1
8.2 Pavement Section Materials 8-5
8.3 Pavement Drainage and Maintenance 8-6
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. 16.53.084 ii Report No. 13950
TABLES AND APPENDICES
TABLES
Table 4-1 Laboratory Testing Program 4-1
Table 5-1 General Relationship between PI and Shrink/Swell Potential 5-2
Table 6-1 Material Excavation and Replacement with Resulting PVR 6-2
Table 6-2 BRAB Design Parameters 6-3
Table 6-3 WRI/CRSI Design Parameters 6-3
Table 7-1 Compaction Equipment and Maximum Lift Thickness 7-1
Table 8-1 Vehicle Classification and Traffic Loading 8-1
Table 8-2 Flexible Pavement Design Values 8-2
Table 8-3 Recommended Minimum Typical Flexible Pavement Thicknesses 8-2
Table 8-4 Rigid Pavement Design Values 8-3
Table 8-5 Recommended Minimum Typical Rigid Pavement Thicknesses 8-4
Table 8-6 Rigid Pavement Components 8-4
APPENDICES
Appendix A: Soil Boring Location Plan
TWE Drawing No. 16.53.084-1
Appendix B: TWE Logs of Project Borings and a Key to
Terms and Symbols used on Boring Logs
TWE Project No. 16.53.084 1-1 Report No. 13950
1 INTRODUCTION AND PROJECT DESCRIPTION
1.1 Introduction
This report presents the results of our geotechnical engineering study performed for the new
Astromatic car wash facility to be constructed at 14502 Northwest Boulevard in Corpus Christi,
Texas. Our geotechnical engineering study was conducted in accordance with TWE Proposal
No. P16-C111, dated December 19, 2016, and authorized by Shane Weiss of Astromatic Car
Wash, LP.
1.2 Project Description
The project involves construction of a new car wash facility with associated parking and
driveway areas. The new building will be one-story with a footprint of about 4,800 square feet.
We anticipate that the structure will be lightly loaded and as a result be supported by a shallow
foundation system bearing on compacted structural fill material. We assume that maximum
loads will be on the order of 100-kips (1 kip = 1,000 lbs.) for concentrated columns and 3 to 4-
kips per lineal foot for wall loads. It is our understanding that the finished floor of the new
building is to remain at or near the existing natural grade (within one to two feet). In addition,
we understand that the at-grade parking areas will be primarily subjected to light traffic
conditions (automobiles and light trucks) with occasional garbage disposal truck traffic.
TWE Project No. 16.53.084 2-1 Report No. 13950
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 three (3) soil boring at the site to depths of 5-ft. to 20-ft. 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 recommendations for suitable foundation system such as a
shallow supported, stiffened beam and slab-on-grade foundation system to support the
proposed new car wash structure and adjacent covered car detailing areas including
allowable net bearing pressure, lateral resistance, uplift resistance and settlement estimates;
4. Providing geotechnical design recommendations for both flexible (asphalt) and 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 guidelines.
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. 16.53.084 3-1 Report No. 13950
3 FIELD PROGRAM
3.1 Soil Borings
TWE conducted an exploration of subsurface soil and groundwater conditions at the project site
on January 3, 2017 by drilling, logging, and sampling three (3) soil borings to depths of 5-ft. to
20-ft. below natural grade at the time of the field program. The soil boring locations are
presented on TWE Drawing No. 16.53.084-1 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. The final latitude and longitude coordinates for
each boring were determined using a handheld GPS unit and are presented on the boring logs in
Appendix A of this report.
3.2 Drilling Methods
Field operations were performed in general accordance with 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 conventional truck-mounted drilling
equipment 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 13.5-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 SPT blowcounts are presented on the boring
logs in Appendix B.
TWE Project No. 16.53.084 3-2 Report No. 13950
3.4 Boring Logs
Our interpretation of the general subsurface materials 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 location of strata changes were based on visual classifications during
field sampling and laboratory testing 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 their
corresponding pocket penetrometer and SPT measurements. 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 drilling. Water
level readings were attempted in the open boreholes when water was first encountered and after a
ten (10) to fifteen (15) min time period. The groundwater observations are summarized in
Section 5.5 of this report entitled “Groundwater Observations.”
TWE Project No. 16.53.084 4-1 Report No. 13950
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 materials encountered within the project
borings.
Laboratory tests were performed in general accordance with ASTM International standards. The
types of 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
TWE Project No. 16.53.084 4-2 Report No. 13950
consistency for plastic soils. The plasticity index is the difference between the liquid limit and
plastic limit.
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, unit weight, Atterberg Limits, grain size distribution,
penetration resistance, shear strength and compressive strength are presented on the project
boring logs in Appendix B of this report.
TWE Project No. 16.53.084 5-1 Report No. 13950
5 SITE 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
could 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
The project site is located at 14502 Northwest Boulevard in Corpus Christi, Texas and covers an
approximate 1 acre tract of land. At the time of our field investigation, the site was dry and
covered with native vegetation (grass and weeds) and was clear of any tress or structures. The
site was observed to be mostly flat, with apparent natural site drainage existing between the
adjacent boulevard right-of-way and the south boundary of the site.
5.3 Subsurface Conditions
The soil profile encountered in the project borings consisted of firm to hard, but occasionally
stiff, cohesive clay soils. Specifically, FAT CLAYS with SAND (CH) and SANDY FAT
CLAYS (CH) were encountered above a depth of 8-ft. in boring B-1 and above the termination
depth of 6-ft. in borings B-2 and B-3. Below the fat clays, LEAN CLAYS with SAND (CL)
were encountered in Boring B-1 and extended to a depth of about 18-ft. below existing grade.
CLAYEY SANDS (SC) were encountered below the lean clays and continued to the termination
depth of 20-ft. 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 49 to 69 with corresponding plasticity indices (PI)
ranging from 34 to 50. In-situ moisture contents of the soils ranged from 16% to 27%. The
amount of material passing the No. 200 sieve ranged from 56% to 76% within the selected
cohesive soil samples tested for grain size distribution.
Undrained shear strengths derived from field pocket penetrometer readings ranged from 1.00-tsf
to 4.50+-tsf. Undrained shear strengths derived from laboratory unconfined compressive (UC)
strength testing ranged from 3.0-tsf to 21.0-tsf with corresponding dry unit weights ranging from
95-pcf to 116-pcf.
The recorded SPT N-values from the semi-cohesionless soil strata encountered at the termination
of boring B-1, were on the order of 20 blows per foot indicating a medium dense relative density
for this stratum. In-situ moisture content tests on the selected semi-cohesionless soil sample was
10% with corresponding amount of materials finer than the No. 200 sieve equal to 48%.
TWE Project No. 16.53.084 5-2 Report No. 13950
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 open boreholes during dry-auger drilling.
Free groundwater was not encountered in the borings at the time of our field exploration.
Groundwater levels may fluctuate with climatic and seasonal variations and should be verified
before construction. Accurate determination of static groundwater level is typically made with a
standpipe piezometer. Installation of a piezometer to evaluate long-term groundwater conditions
was not included in our scope of services.
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 5-1 below.
Table 5-1:
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 magnitude of overburden. Overall, the soils at this site possess a high to very
high shrink/swell potential.
TWE Project No. 16.53.084 6-1 Report No. 13950
6 GEOTECHNICAL RECOMMENDATIONS
6.1 Discussion
The cohesive soils encountered above a depth of about 18-ft. at this site are plastic fat clays with
sand, sandy fat clays and lean clays with sand, which can experience high to very high
shrink/swell movements with change in moisture content. Based on the expansive nature of the
clay soils, we recommend that the proposed facility be supported on a foundation system that
consists of a stiffened shallow beam and slab foundation supported by a prepared building pad
constructed of non-expansive fill material. Recommendations for design and construction of a
conventionally reinforced, stiffened, waffle type monolithic beam and slab-on-grade foundation
are provided below. Additionally, earthwork recommendations are provided in Section 7 of this
report entitled “Earthwork Considerations”. Recommendations for area pavement including
flexible and rigid paving sections and material properties are provide in Section 8 of this report
entitled “Pavement Design Recommendations”.
Alternatively, a foundation system consisting of drilled and underreamed piers can be provided
upon request. However, keep in mind, with the use of a drilled pier foundation system, the
interior floor slab will need to be supported by a prepared building pad constructed of non-
expansive fill material.
6.2 Stiffened, Conventionally Reinforced, Waffle-Type Beam and
Slab-on-Grade Foundation System
Surface and near surface soils encountered in the project borings for this site possess a high to
very high shrink/swell potential with changes in moisture content. It is generally accepted that a
primary source of foundation distress is movement associated with the shrink/swell of the
underlying support soils. It is therefore recommended that measures be incorporated into the
design of the foundation system for the proposed building that will reduce the shrink/swell
potential of the foundation soils.
6.2.1 6.2.1 Building Pad Preparation
Based on the results of our field and laboratory programs, the Potential Vertical Rise (PVR) for
the existing subsurface stratigraphy at the site determined by Test Method TEX-124-E is
calculated to be about 3.5 to 4.0-in. for “existing” conditions. Since stiffened conventionally
reinforced beam and slab-on-grade foundations are usually designed and constructed for potential
soil movements of 1-in. or less, a means of reducing potential movements should be used for the
project. One of the most feasible and viable means in this area is removal of part of the existing
surface and near surface soils and replacements with non-expansive structural select fill.
Ultimately, 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 is determined
by the structural engineer. A summary of PVR values with corresponding excavation and
replacement material amounts for “dry” moisture conditions is provided in Table 6-1 on the
following page. This method has beneficial results but does not totally eliminate the potential for
shrink/swell movements.
TWE Project No. 16.53.084 6-2 Report No. 13950
Table 6-1:
Material Excavation and Replacement with Resulting PVR
Amount of Excavation (feet) Amount of Replacement (feet) Resulting PVR (in.)
4 4 2.0 to 2.5
6 6 1.5 to 1.75
8 8 < 1.0
Based on these results, we recommend that site preparation include:
Removal of the existing soils, extending to at least 5-ft. beyond the outside perimeter of
the foundation, and 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 material should be placed to at least 5-ft beyond the outside
perimeter of the foundation, as listed in Table 6-1.
Maintain moisture in select fill pad until the concrete foundation is constructed.
The subgrade to receive non-expansive structural fill should be proof-rolled and compacted as
indicated below in Section 7.1. The bottom of the grade beams and the slab should be founded in
properly compacted non-expansive structural select fill.
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.
TWE Project No. 16.53.084 6-3 Report No. 13950
6.2.2 Foundation Design Parameters
A stiffened, conventionally reinforced, waffle-type beam and slab-on-grade foundation should be
designed and constructed to resist movements of the supporting soils without inducing distress to
the superstructure or foundation. The rigidity of the foundation results from grade beams that
begin at perimeter of the foundation and criss-cross the interior of the foundation forming a
“waffle” pattern. The foundations are often designed using the BRAB or WRI/CRSI design
methodologies. These methods are similar and design parameters for each are provided below.
The conventionally reinforced, monolithic beam and slab-on-grade foundation can be designed
using the BRAB design parameters presented below in Table 6-2.
Table 6-2: BRAB Design Parameters
Effective Plasticity Index (PIeff) 41
Climatic Rating (Cw) 17
Support Index (C) 0.73
Unconfined Compressive Strength (tsf) 1.25
Alternatively, the foundation can be designed using the WRI/CRSI design parameters presented
in Table 6-3 below.
Table 6-3: WRI/CRSI Design Parameters
Effective Plasticity Index (PIeff) 41
Climatic Rating (Cw) 17
1- C 0.27
TWE Project No. 16.53.084 6-4 Report No. 13950
Grade beams should bear at a minimum depth of 30-in below finished grade in properly
compacted non-expansive structural select fill. Grade beams can be designed as strip footings
using an allowable bearing pressure of 2,500 psf. Concentrated loads can be supported by
enlarged areas that are designed as spread footings. Spread footings founded at a depth of at least
30-in below finished grade can be designed using an allowable bearing pressure of 2,700 psf.
These allowable bearing pressures should provide a factor of safety of at least 3.0 against soil
shear failure. Spread footings and grade beams should have minimum widths of 36-in and 18-in,
respectively, even if the actual bearing pressure is less than the design value.
If weak, soft, wet or otherwise unsuitable fill soils are encountered during construction at the
recommended foundation depth, we recommend that either the unsuitable materials should be over-
excavated, dried, and re-compacted in accordance with requirement for select fill or the foundation
depth be extended to the depth of competent soil lying beneath the unsuitable soil. The footing
excavations should not be allowed to remain open for extended periods. If footings are to remain
open, the use of a lean concrete mud mat to reduce moisture changes or other disturbance to the
bearing soils should be considered.
6.3 Uplift Resistance
Resistance to vertical force (uplift) is provided by the weight of the concrete foundation plus the
resistance of the foundation to rotation. For this site, the bearing pressures presented above when
applied at the foundation toe can be increased by 30% for transient loads such as wind loads.
The calculated ultimate uplift resistance should be reduced by a factor of safety of 1.2 to
calculate the allowable uplift resistance.
6.4 Lateral Resistance
Horizontal loads acting on shallow foundations below grade will be resisted by some passive
resistance acting on one side of the foundation and through adhesion acting on the base of the
foundation. An allowable passive pressure of 500-psf can be used for the natural undisturbed
soils and/or properly compacted structural select fill material used as backfill around the
foundation. An allowable base adhesion of 300-psf can be used for foundations in good contact
with properly compacted structural select fill at the recommended foundation depth. These
values should provide a factor of safety of about 2.0 with respect to the ultimate values.
6.5 Settlement
Estimated settlement for the shallow waffle-type foundation placed at the recommended depth is
based on our experience, the shear strength from the project borings, and proper preparation of
the building pad. This estimate assumes a uniformly loaded foundation with pressures that are
no greater than the recommended allowable bearing pressures and assume the foundation is
designed and constructed in accordance with the recommendations provided in this report.
Settlement of properly designed and installed foundation is estimated to be on the order of less
than 1-in. Differential settlement across the foundation could be on the order of about one-half
(1/2) the total settlement.
TWE Project No. 16.53.084 6-5 Report No. 13950
6.6 Shallow Foundation Construction
The performance of shallow foundation systems associated with the project will be highly
dependent upon the quality of construction. Thus, it is recommended that shallow foundation
construction be monitored by a representative of TWE experienced in quality control testing and
inspection procedures to help evaluate foundation construction. TWE would be pleased to
develop a plan for shallow foundation monitoring to be incorporated in the overall quality control
program.
TWE Project No. 16.53.084 7-6 Report No. 13950
7 EARTHWORK CONSIDERATIONS
7.1 Subgrade Preparation and Structural Select Fill
Areas designated for new construction should be stripped of all surface vegetation, loose topsoil
and major root systems. Tree stumps shall be completely removed and backfilled, if applicable.
After planned subgrade elevation has been reached, the exposed subgrade should then 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 upper 6-in of the exposed subgrade in
foundation areas should be compacted to at least 95% of the maximum dry density at or above (0
to +4 percent) 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.
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, select 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
18. The select fill should be placed in thin lifts, not exceeding 8-in loose measure, moisture
conditioned to between ±2% 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. 16.53.084 7-7 Report No. 13950
7.2 Drainage
Positive drainage away from excavations should be established to avoid surface water from ponding
within excavations and around the work area.
The performance of the foundation system for the proposed building 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 does not occur. Accumulations of water near the structure
foundation could cause moisture variations in the soils adjacent to the foundation thus increasing
the potential for structural distress. The soils supporting the associated utilities should also be
protected against disturbance from construction activities, and moisture changes.
TWE Project No. 16.53.084 8-1 Report No. 13950
8 PAVEMENT DESIGN RECOMMENDATIONS
8.1 Pavement Design Criteria
For the proposed use of driveways and parking areas, and accounting for the shallow subsurface
soil conditions encountered in the project borings, either a flexible or a rigid pavement system can
be considered. 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 flexible and 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 Flexible Pavement Design
The primary design requirements needed for flexible pavement design according to the Pavement
Design Guide included the following:
Material Layer Coefficient;
Soil Resilient Modulus, psi;
Serviceability Indices;
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 analysis are presented in Table 8-2 on the following page.
TWE Project No. 16.53.084 8-2 Report No. 13950
It should be noted that these systems were derived based on general soil characterization of the
subgrade. No specific testing (such as CBR's, resilient modulus tests, etc.) was performed for this
project to evaluate the support characteristics of the subgrade.
Table 8-2:
Flexible Pavement Design Values
Description Value
Material Coefficients
Hot Mix Asphalt Concrete (HMAC), Type D 0.44
Crushed Limestone (Type A, Grade 2 or better) [CLS] 0.14
Lime Stabilized Subgrade (LSS) 0.08
Serviceability Indices Initial 4.2
Terminal 2.5
Soil Resilient Modulus 3,000-psi
Drainage Coefficient 1.0
Overall Standard Deviation 0.45
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
Structural Number Required – DI-1 2.40
Structural Number Required – DI-2 3.23
Table 8-3 below provides the recommended minimum typical pavement section derived from our
analysis using the AASHTO Guide.
Table 8-3:
Recommended Minimum Typical Flexible Pavement Thicknesses
Traffic Design Index HMAC,
Type D CLB LSS SN
DI-1 2.0-in 8.0-in 8.0-in 2.64
DI-2 3.0-in 12.0-in 8.0-in 3.64
HMAC = Hot Mix Asphalt Concrete
CLB = Crushed Limestone Base (Type A, Grade 2 or better)
LSS = Lime Stabilized Subgrade
SN = Structural Number Provided by Pavement
TWE Project No. 16.53.084 8-3 Report No. 13950
8.1.2 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 8-4 on the following page.
Table 8-4: 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 8-5 on the following page provides the recommended minimum typical pavement section
derived from our analysis using the AASHTO Pavement Design Guide.
TWE Project No. 16.53.084 8-4 Report No. 13950
Table 8-5: Recommended Minimum Typical Rigid Pavement Thicknesses
Traffic Design Index RC LSS
DI-1 5.0-in 8.0-in
DI-2 7.0-in 8.0-in
RC = Reinforced Portland Cement Concrete
LSS = Lime Stabilized 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 8-6 below presents these
guidelines.
Table 8-6: 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.
TWE Project No. 16.53.084 8-5 Report No. 13950
8.2 Pavement Section Materials
Hot Mix Asphalt Concrete (HMAC), Type D
HMAC, Type D should conform to Item 340, “Dense-Graded Hot-Mix Asphalt” of the Texas
Department of Transportation (TxDOT) 2004 Standard Specifications for Construction and
Maintenance of Highways, Streets and Bridges. The HMAC should provide a minimum tensile
strength (dry) of 85 to 200 psi when tested in accordance with TxDOT Test Method Tex-226-F,
and should be compacted at 96% of the theoretical density as determined from the asphaltic
mixture design prepared in accordance with TxDOT Test Method Tex-207-F “Determining
Density of Compacted Bituminous Mixtures”.
Crushed Limestone Base (CLB)
CLB should conform to TxDOT, Item No. 247 “Flexible Base”, Type A, Grade 2 or better and
should be compacted to 100% of the maximum dry density determined by TxDOT Test Method
Tex-113-E within ±2% of the optimum moisture content.
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 is recommended for the pavement sections included in
Tables 8-3 and 8-5 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
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.
TWE Project No. 16.53.084 8-6 Report No. 13950
Once final subgrade elevation is achieved and prior to placement of reinforced concrete wearing
surface or crushed limestone base material, 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. After lime addition and proper curing, the stabilized material should be pulverized in
accordance with TxDOT requirements in preparation for final compaction. The lime stabilized
subgrade should be then 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 base material and/or 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. 16.53.084 9-1 Report No. 13950
9 LIMITATIONS AND DESIGN REVIEW
9.1 Limitations
This report has been prepared for the exclusive use of Astromatic Car Wash, LP and the project
team for specific application to the design and construction of the proposed new Astromatic Car
Wash facility 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 boring indicates
subsurface conditions only at the specific locations, times and depths penetrated. The soil boring
does 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 can be confirmed only during
construction of the new foundation system. 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. 16.53.084 Report No. 13950
APPENDIX A
SOIL BORING LOCATION PLAN
TWE DRAWING NO. 16.53.084-1
COPYRIGHT © 2015 GOOGLE EARTH. ALL RIGHTS RESERVED.
COPYRIGHT © 2015 GOOGLE MAP. ALL RIGHTS RESERVED.
B-1
B-2
B-3
TWE Project No. 16.53.084 Report No. 13950
APPENDIX B
TWE LOGS OF PROJECT BORINGS AND A KEY TO
TERMS AND SYMBOLS USED ON BORING LOGS
0
3
6
9
12
15
18
21
Firm to hard dark gray FAT CLAY with SAND (CH),gypsum crystals and ferrous stains
-color changes to dark gray and gray
-color changes to gray and tan with calcareous nodules
Very stiff to hard gray and tan LEAN CLAY with SAND(CL), gypsum crystals and ferrous stains
-color changes to gray, tan and light brown
Medium dense tan CLAYEY SAND (SC) with gypsumcrystals and ferrous stains
Bottom @ 20'
(P) 1.25
(P) 4.50+
(P) 4.50+
(P) 4.50+
(P) 4.50+
(P) 4.50+
(P) 3.00
9/6"10/6"10/6"
26
17
20
21
10
96
116
108
105
65
49
49
34
20.87
3.02
10
3
70
72
76
72
48
TOLUNAY-WONG ENGINEERS, INC.
LOG OF BORING B-1PROJECT: New Car Wash
Corpus Christi, TexasCLIENT: Astromatic Carwash, LP.
COMPLETION DEPTH: 20 ft REMARKS: Ground water was not encountered during dry-auger drilling. At thecompletion of drilling, the open borehole was backfilled with soil cuttings.DATE BORING STARTED: 01/03/2017
DATE BORING COMPLETED: 01/03/2017LOGGER: J. GonzalezPROJECT NO.: 16.53.084
Page of1
DE
PT
H (
ft)
SA
MP
LE
TY
PE
SY
MB
OL/U
SC
S
MATERIAL DESCRIPTION
COORDINATES: N 27° 51' 29.1"W 97° 38' 57.3"
SURFACE ELEVATION: --DRILLING METHOD:
Dry Augered: 0-ft. to 20-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
0
3
6
9
12
15
18
21
Firm to hard dark gray and gray FAT CLAY with SAND(CH), gypsum crystals and ferrous stains
Hard dark gray and gray SANDY FAT CLAY (CH) withgypsum crystals and ferrous stains
Bottom @ 6'
(P) 1.00
(P) 4.50
(P) 4.50
25
16
100
110
55
69
38
50 14.01 4
72
56
TOLUNAY-WONG ENGINEERS, INC.
LOG OF BORING B-2PROJECT: New Car Wash
Corpus Christi, TexasCLIENT: Astromatic Carwash, LP.
COMPLETION DEPTH: 6 ft REMARKS: Ground water was not encountered during dry-auger drilling. At thecompletion of drilling, the open borehole was backfilled with soil cuttings.DATE BORING STARTED: 01/03/2017
DATE BORING COMPLETED: 01/03/2017LOGGER: J. GonzalezPROJECT NO.: 16.53.084
Page of1
DE
PT
H (
ft)
SA
MP
LE
TY
PE
SY
MB
OL/U
SC
S
MATERIAL DESCRIPTION
COORDINATES: N 27° 51' 30.0"W 97° 38' 58.5"
SURFACE ELEVATION: --DRILLING METHOD:
Dry Augered: 0-ft. to 5-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
0
3
6
9
12
15
18
21
Stiff to hard dark gray FAT CLAY with SAND (CH),gypsum crystals and ferrous stains
-color changes to dark gray and gray
Bottom @ 6'
(P) 3.50
(P) 2.75
(P) 4.50+
27
24
20
95
100
105
66
63
43
43
3.74
11.36
5
8
71
76
76
TOLUNAY-WONG ENGINEERS, INC.
LOG OF BORING B-3PROJECT: New Car Wash
Corpus Christi, TexasCLIENT: Astromatic Carwash, LP.
COMPLETION DEPTH: 6 ft REMARKS: Ground water was not encountered during dry-auger drilling. At thecompletion of drilling, the open borehole was backfilled with soil cuttings.DATE BORING STARTED: 01/03/2017
DATE BORING COMPLETED: 01/03/2017LOGGER: J. GonzalezPROJECT NO.: 16.53.084
Page of1
DE
PT
H (
ft)
SA
MP
LE
TY
PE
SY
MB
OL/U
SC
S
MATERIAL DESCRIPTION
COORDINATES: N 27° 51' 28.5"W 97° 38' 58.5"
SURFACE ELEVATION: --DRILLING METHOD:
Dry Augered: 0-ft. to 5-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