geotechnical engineering study new astromatic car...

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

ron

Typewritten Text

ron

Typewritten Text

Proposal 2856

mailto:[email protected]

ron

Typewritten Text

ron

Typewritten Text

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.


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.


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.


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.”


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


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.


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%.


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.


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.


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.


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


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.


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.


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.


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.


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.


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


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.


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.


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.


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.


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

AutoCAD SHX Text

Boring Location Plan New Car Wash Astromatic Car Wash LP. Corpus Christi, Texas

AutoCAD SHX Text

SOIL BORING LOCATION

AutoCAD SHX Text

PROJECT LOCATION

AutoCAD SHX Text

Drawn

AutoCAD SHX Text

Scale

AutoCAD SHX Text

Checked

AutoCAD SHX Text

Approved

AutoCAD SHX Text

BORING

AutoCAD SHX Text

LONGITUDE

AutoCAD SHX Text

LATITUDE

AutoCAD SHX Text

DEPTH

AutoCAD SHX Text

LEGEND

AutoCAD SHX Text

SOIL BORING COORDINATES

AutoCAD SHX Text

SYMBOL

AutoCAD SHX Text

DESCRIPTION

AutoCAD SHX Text

TWE DRAWING NO.

AutoCAD SHX Text

VICINITY MAP

AutoCAD SHX Text

R.S.

AutoCAD SHX Text

01/04/2017

AutoCAD SHX Text

R.A.S.

AutoCAD SHX Text

01/04/2017

AutoCAD SHX Text

D.R.R.

AutoCAD SHX Text

01/23/2017

AutoCAD SHX Text

N.T.S.

AutoCAD SHX Text

16.53.084-1

AutoCAD SHX Text

B-1

AutoCAD SHX Text

20'

AutoCAD SHX Text

N 27° 51' 29.1"

AutoCAD SHX Text

W 97° 38' 57.3"

AutoCAD SHX Text

B-2

AutoCAD SHX Text

5'

AutoCAD SHX Text

N 27° 51' 30.0"

AutoCAD SHX Text

W 97° 38' 58.5"

AutoCAD SHX Text

B-3

AutoCAD SHX Text

5'

AutoCAD SHX Text

N 27° 51' 28.5"

AutoCAD SHX Text

W 97° 38' 58.5"

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






Page of1

DE

PT

H (

ft)

SA

MP

LE

TY

PE

SY

MB

OL/U

SC

S


COORDINATES: N 27° 51' 30.0"W 97° 38' 58.5"



(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






Page of1

DE

PT

H (

ft)

SA

MP

LE

TY

PE

SY

MB

OL/U

SC

S


COORDINATES: N 27° 51' 28.5"W 97° 38' 58.5"



(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

geotechnical engineering study new astromatic car...

Documents