GEOTECHNICAL ENGINEERING REPORT

BOARDWALK REPLACEMENT

400 E. JOHNSON

ARANSAS PASS, TEXAS

Prepared for:

LJA Engineering, Inc.

1904 W. Grand Parkway N., Suite 100

Katy, Texas 77449

Prepared by:

Tolunay-Wong Engineers, Inc.

826 South Padre Island Drive

Corpus Christi, Texas 78416

September 12, 2024

Project No. 24.53.069/Report No. 34979

826 South Padre Island Drive • Corpus Christi, Texas 78416 • Phone (361) 884-5050

September 12, 2024

LJA Engineering, Inc.

1904 W. Grand Parkway N., Suite 100

Katy, Texas 77449

Attn: Mr. Gunner McCann

Via email: gmccann@lja.com

Ref: Geotechnical Engineering Study

Boardwalk Replacement

400 E. Johnson

Aransas Pass, Texas

TWE Project No. 24.53.069 / Report No. 34979

Dear Mr. McCann, Tolunay-Wong Engineers, Inc. (TWE) is pleased to submit this report of our geotechnical engineering study for the above referenced project. This report contains a detailed description of the field program and laboratory services performed for this geotechnical engineering study as well as soil boring logs.

Also included in this report are our geotechnical design and construction recommendations for suitable foundation systems for the replacement boardwalk.

We appreciate the opportunity to work with you on this phase of the project and look forward to the opportunity of providing additional services as the project progresses. If you have any questions or comments regarding this report or if we can be of further assistance, please contact us.

Sincerely, TOLUNAY-WONG ENGINEERS, INC.

Texas Board of Professional Engineers Firm Registration Number F-000124

Justin Buchen Don R. Rokohl, P.E.

Geotechnical Staff Engineer Branch Manager

Corpus Christi, Texas Corpus Christi, Texas

JB/DRR/jb mailto:gmccann@lja.com jbuchen Date

TWE

Project No. 24.53.069 i Report No. 34979

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 Boring 3-1

3.2 Drilling Methods 3-1

3.3 Soil Sampling 3-1

3.4 Boring Log 3-1

3.5 Groundwater Measurements 3-2

4 LABORATORY SERVICES 4-1

5 SITE AND SUBSURFACE CONDITIONS 5-1

5.1 General 5-1

5.2 Site Description and Surface Conditions 5-1

5.3 Subsurface Soil Stratigraphy and Properties 5-1

5.4 Groundwater Observation 5-1

5.5 Shrink / Swell Potential 5-2

6 FOUNDATION RECOMMENDATIONS 6-1

6.1 Discussion 6-1

6.2 Driven Timber Pile Foundation Allowable Axial Capacity 6-1

6.3 Lateral Capacity 6-2

6.4 Static Axial Group Effects 6-2

6.5 Pile Installation 6-4

7 EARTHWORK CONSIDERATIONS 7-1

7.1 Subgrade Preparation and Structural Select Fill 7-1

7.2 Drainage 7-2

8 DESIGN REVIEW AND LIMITATIONS 8-1

8.1 Design Review and Construction Monitoring 8-1

8.2 Limitations 8-1

ii Report No. 34979

TABLES

Table 4-1 Laboratory Testing Program 4-1

Table 5-1 Groundwater Level Measurements 5-2

Table 5-2 General Relationship Between PI and Shrink/Swell Potential 5-2

Table 6-1 Recommended Pm Values 6-3

Table 7-1 Compaction Equipment and Maximum Lift Thickness 7-1

APPENDICES

Appendix A: Soil Boring Location Plan

TWE Drawing No. 24.53.069-1

Appendix B: Logs of Project Borings and a Key to

Terms and Symbols used on Boring Logs

Appendix C: Allowable Axial Pile Capacity Curves

Appendix D: LPILE Soil Design Parameters and Analysis Results

1-1 Report No. 34979

1 INTRODUCTION AND PROJECT DESCRIPTION

1.1 Introduction

This report presents the results of our geotechnical engineering services performed for the replacement boardwalk at the overlook site at 400 E. Johnson Street in Aransas Pass, Texas. Our geotechnical engineering study was conducted in accordance with TWE Proposal No. P24-C081, dated June 14, 2024, and authorized by Work Authorization, dated July 30, 2024, for LJA Job No.

C285-22117.

1.2 Project Description

The project involves the replacement of an existing boardwalk structure at the municipal facility at 400 E. Johnson Street in Aransas Pass, Texas. The existing boardwalk is about 400 feet in length and used by pedestrian foot traffic only. It is anticipated the new boardwalk structure will be supported with driven timber poles.

2-1 Report No. 34979

2 PURPOSE AND SCOPE OF SERVICES

The purposes of our geotechnical engineering services were to provide geotechnical information needed to assist the Client in the design and construction of suitable foundations for the boardwalk.

Our scope of services performed for the project consisted of:

1. Drilling three (3) soil borings to depths of 20-ft within the project site to evaluate subsurface stratigraphy and groundwater conditions;

2. Performing geotechnical laboratory tests on recovered soil samples to evaluate the physical and engineering properties of the strata encountered;

3. Providing geotechnical engineering design recommendations for the boardwalk improvements/replacement. The recommendations will include driven timber pile foundations for support of the boardwalk as well as construction considerations; and,

4. Providing geotechnical construction recommendations including site and subgrade preparation, excavation considerations, fill and backfill placement, compaction requirements, foundation installation, and overall quality control monitoring, inspection, and testing services.

Our scope of services did not include any environmental assessments for the presence or absence of wetlands or of hazardous or toxic materials within or on the soil, air or water within this project site. Any statements in this report or on the boring logs regarding odors, colors or unusual or suspicious items or conditions are strictly for the information of the Client. A geological fault study was also beyond the scope of our services associated with this geotechnical engineering study.

3-1 Report No. 34979

3 FIELD PROGRAM

3.1 Soil Borings

TWE conducted an exploration of subsurface soil and groundwater conditions at the project site on August 9th, 2024 by drilling and sampling three (3) soil borings to depths of 20-ft below existing grade at time of the field program. The soil boring locations are presented on TWE Drawing No.

24.53.069-1 in Appendix A of this report. Our field personnel coordinated the field activities and logged the boreholes. The boring locations were staked or marked at the site by TWE geotechnical technicians. The final latitude and longitude coordinates for the borings were verified by TWE geotechnical technicians using a hand-held GPS unit and are presented on the boring log in

Appendix B of this report.

3.2 Drilling Methods

Field operations were performed in general accordance with the Standard Practice for Soil

Investigation and Sampling by Auger Borings [American Society for Testing and Materials

(ASTM) D 1452]. The soil borings were drilled using all-terrain-vehicle (buggy) mounted drilling equipment using wet rotary drilling methods. Samples were obtained continuously until boring completion depth was reached.

3.3 Soil Sampling

Cohesionless and semi-cohesionless soil samples, and where soils that could not be sampled with tube samplers, 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 semi-cohesionless samples are inferred from the N-value. The samples obtained from the split-barrel sampler were visually classified, placed in moisture sealed containers and transported to our laboratory.

The recovered soil sample depths with corresponding pocket penetrometer measurements and SPT blow-counts are presented on the boring logs in Appendix B.

3.4 Boring Logs

Our interpretations of general subsurface soil and groundwater conditions at the soil boring location are included on the boring logs. Our interpretations of the soil types throughout the boring depths and the locations of strata changes were based on visual classifications during field sampling and laboratory testing in accordance with Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System) (ASTM D 2487) and Standard

Practice for Description and Identification of Soils (Visual-Manual Procedure) (ASTM D 2488).

The boring logs include the type and interval depth for each sample along with its corresponding pocket penetrometer measurements. The boring logs and a key to terms and symbols used on boring logs are presented in Appendix B.

3-2 Report No. 34979

3.5 Groundwater Measurements

Groundwater level measurements were attempted in the open boreholes during dry-auger drilling.

Water level readings were attempted in the open boreholes when groundwater was first encountered and after a fifteen (15) minute time period. The groundwater observations are summarized in Section 5.4 of this report entitled “Groundwater Observations.”

4-1 Report No. 34979

4 LABORATORY SERVICES

A laboratory testing program was conducted on selected samples to assist in classification and evaluation of the physical and engineering properties of the soils encountered in the project borings.

Laboratory tests were performed in general accordance with ASTM International standards. The types of 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

Water (Moisture) Content of Soil ASTM D 2216

Liquid Limit, Plastic Limit and Plasticity Index of Soils ASTM D 4318

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.

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.

Standard geotechnical laboratory test results and soil properties encountered in the project borings are presented on the boring logs in Appendix B of this report.

5-1 Report No. 34979

5 SITE AND SUBSURFACE CONDITIONS

5.1 General

Our interpretations of soil and groundwater conditions within the project site are based on information obtained at the soil boring locations only. This information has been used as the basis for our geotechnical information included in this report. Subsurface conditions may vary at areas not explored by the soil borings. Significant variations at areas not explored by the soil borings will require reassessment of our geotechnical information.

5.2 Site Description and Surface Conditions

The borings are located in the vicinity of an existing boardwalk located at 400 E. Johnson Ave. in

Aransas Pass, Texas. At the time of our field exploration the ground surface consisted of loose sand covered by ground vegetation.

5.3 Subsurface Soil Stratigraphy and Properties

A general subsurface profile was developed from the subsurface soils encountered within the project borings. Detailed descriptions of the soils encountered at the boring locations are presented on the boring logs in Appendix B. The general soil profile encountered consisted of very loose to medium dense semi-cohesionless and cohesionless soil CLAYEY SAND (SC) and POORLY

GRADED SAND w/ CLAY (SP-SC) throughout the boring depths of 20-ft below existing grade at the time of borings.

Results of Atterberg Limit tests on selected semi-cohesionless and cohesionless soil samples from the project borings indicated liquid limits (LL) ranging from non-plastic to 30 with corresponding plasticity indices (PI) ranging from non-plastic to 18. In-situ moisture contents from tests performed on the selected semi-cohesionless and cohesionless samples ranged from 18% to 28%.

The amount of materials finer than the No. 200 sieve on the selected samples ranged from 9% to

24%. Based on the SPT results, the semi-cohesionless and cohesionless soils encountered in the boring are inferred to have medium dense to dense relative densities.

Detailed descriptions of the soils encountered at the boring locations are presented on the boring logs in Appendix B.

5.4 Groundwater Observations

Groundwater measurements were attempted in the project borings during dry-auger drilling.

Observations of groundwater encountered during dry-auger drilling are presented in Table 5-1 on the following page.

5-2 Report No. 34979

Table 5-1: Groundwater Level Measurements

Boring No.

Boring Depth (feet)

Groundwater Level Depth

Free Water During Drilling

(feet) 15 Minute Static Water Level (feet)

B-1 20 1.5 1.0

B-2 20 5.0 4.9

B-3 20 2.0 1.8

Groundwater levels may fluctuate with climatic and seasonal variations and should be verified before construction. Accurate determination of the static groundwater level is typically made with a standpipe piezometer. Installation of a piezometer to evaluate the long-term groundwater condition was not included within the current scope of services.

We recommend a groundwater level that is equivalent to finished grade be used for foundation design purposes.

5.5 Shrink / Swell Potential

The tendency for a soil to shrink and swell with change in moisture content is a function of clay content and type which are generally reflected in soil consistency as defined by Atterberg Limits. A generalized relationship between shrink/swell potential and soil plasticity index (PI) is shown in Table

5-2 below.

Table 5-2:

General Relationship Between PI and Shrink/Swell Potential

P.I. Range Shrink/Swell Potential

0 – 15 Low

15 – 25 Medium

25 – 35 High

> 35 Very High

The amount of expansion that will actually occur with increase in moisture content is also inversely related to the overburden pressure. That is, 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 lower magnitudes of overburden. Overall, the soils at this site possess low shrink/swell potential.

6-1 Report No. 34979

6 FOUNDATION RECOMMENDATIONS

6.1 Discussion

The project involves improvements or replacement of an existing boardwalk located at 400 E.

Johnson Avenue in Aransas Pass, Texas. The existing boardwalk is about 400-ft in length and is used for pedestrian foot traffic only.

Due to the very loose to loose very sandy soils in the upper 10-ft of soils along with the relatively shallow water table, conventional shallow footings or underreamed footings are not recommended for this project. It is noted that timber piling is the preferred foundation system for this project.

Recommendations for design and construction of these foundations are provided below. If other foundation types are desired, recommendations can be provided upon request.

6.2 Driven Timber Pile Foundation Allowable Axial Capacity

Allowable Axial Capacity

Driven timber piles can be considered for support of the new and/or improved boardwalk project in Aransas Pass, Texas. Geotechnical design and construction recommendations for these piles are provided in the following sections.

We estimated allowable compression and tension pile capacities for driven round timber piles for this project using the static method of analysis recommended by the American Petroleum Institute

(API). The analyses were performed using the computer code APILE Plus, Version 2023 (Ensoft, Inc.). The allowable axial pile capacity curves for 5-in tip/8-in butt, 6-in tip/10-in butt, and 8-in tip/12-in butt timber piles are provided on Figures 1 through 3 in Appendix C of this report. It should be noted that the allowable compressive and tensile capacities for driven piles have been neglected above 5-ft. below existing ground surface.

The allowable capacity curves for the driven piles at the site are provided in Figures 1 through 3 in Appendix C of this report and contain a minimum factor of safety of 3.0 against bearing capacity. Pile capacities taken from the pile capacity curves provided for individual piles having a minimum center-to-center spacing of at least three (3) pile diameters. The pile depths listed are measured from existing ground surface. It should be noted that the tensile capacity is based solely on soil-pile interaction. Piles and pile connections should be structurally capable of resisting design uplift loads.

Individual Pile Settlement

Groups of piles having a center-to-center spacing of less than three (3) diameters should be analyzed for group efficiency. If pile groups are planned for this project with spacing less than three (3) pile diameters, TWE should be contacted to analyze group capacities and settlements once the final pile size, depth and group configurations are selected.

Assuming proper installation, the total settlement of a single driven pile using the allowable compression capacities calculated as presented in Figures 1 through 3 of Appendix D is anticipated to be less than 1.0 in. The settlement of a single pile will predominantly be elastic in nature.

6-2 Report No. 34979

6.3 Lateral Capacity

For driven pile foundations, lateral loads are resisted by the soil-structure interaction as well as the rigidity of the pile. Lateral capacity will vary with pile type and properties, degree of fixity and pile spacing. Typically, lateral loads are analyzed using the p-y method in which the soil is modeled as a series of non-linear springs. This procedure with appropriate computer codes (i.e., LPILE by Ensoft, Inc.) has the advantage that major factors influencing soil resistance are inherently included in the semi-empirical p-y design criteria. Detailed analyses can be performed using the final pile size and configuration upon request for additional compensation.

For subsurface conditions indicated by the soil borings, our recommended soil design parameters based on the general site soil profile is presented in Appendix D of this report for use with lateral load analysis of piles for this project.

6.4 Static Axial Group Effects

The following method can be used to determine the axial capacity and efficiency of pile groups.

To evaluate capacity, two (2) distinct failure modes are considered. In the first mode, a block-type behavior is assumed in which the piles and confined soil mass encompassed by the group act as a unit. The ultimate bearing capacity of the unit, Qc, is equal to the ultimate load carried in friction by the circumferential area of the group plus the ultimate load resistance derived from the base of the assumed equivalent pier/pile.

Qc = fsAc + qbAb fs = Ultimate Unit Soil-Pile Adhesion (psf)

Ac = Circumferential Embedded Area of Equivalent Pier (ft) qb = Ultimate Unit End Bearing (psf)

Ab = Base Area of Equivalent Pier (ft2)

In the second mode of failure, it is assumed the piles in the group act individually. The ultimate bearing capacity of the group, Qc, considering individual mode of failure is determined by multiplying the number of piles in a group by the ultimate load carrying capacity of individual piles.

Qc = ∑Qi

Qi = Ultimate Capacity of Individual Piles in the Group

The lower of the two (2) capacities of the group considering block mode of failure and individual mode of failure is taken as the required ultimate capacity of the pile group. The group efficiency is defined as the ratio of the group capacity considering block mode of failure and the group capacity considering individual mode of pile failure.

A pile group is considered safe against bearing failure if the number of piles in the group times the applied design load per pile does not exceed Qc/F.S. (F.S. = Factor of Safety). If the total group design load is greater than Qc/F.S., one (1) alternative is to reduce the design load for individual piles within the group accordingly. Based on this approach to pile group capacity analysis, pile spacing can be determined in which full capacity of individual piles is utilized. Generally, a pile spacing of at least three (3) pile diameters, center-to-center, is selected as a first approximations.

6-3 Report No. 34979

Settlement of Pile Groups

The settlement of a group of piles is significantly influenced by the size of the pile group, and the compressibility of the soils below the pile tip. For typical pile spacing of about three (3) pile widths/diameters center-to-center, settlement estimates of pile groups (4x4 or larger) should be performed on a case-by-case basis once the pile group geometry, footprint, pile tip elevations, and group load have been selected.

Lateral Group Effects

Piles subjected to lateral loading are commonly designed using the p-y method in which the soil is modeled as a series of non-linear springs. This procedure is used with appropriate computer codes (i.e., LPILE by Ensoft, Inc., or equivalent) and has the advantage that the major factors influencing lateral soil resistance are inherently included in the semi-empirical p-y design criteria.

The effects of a close pile spacing results primarily in a reduction in the maximum soil resistance which can be mobilized, and thus leads to the concept of a “p-multiplier”. A factor, Pm, can be applied to a single p-y by multiplying the soil resistance values “p” by Pm to compute a p-y which includes the pile group effects. This concept is shown on the figure provided below.

The selection of the appropriate p-multiplier factor depends on if the pile is located in the front or

“leading” row or in the back or “trailing” row in the direction of loading. Recommended Pm values for front row and back row piles are presented in Table 6-1 (Mokwa and Duncan, 2001) below.

Table 6-1: Recommended Pm Values

Pile Spacing

(center to center)

Leading

Row

1st Trailing

Row

2nd

Trailing

Row

3rd and Subsequent

Trailing Rows

3 Diameters 0.82 0.68 0.58 0.52

4 Diameters 0.90 0.78 0.72 0.68

5 Diameters 0.94 0.89 0.86 0.84

6 Diameters 1.0 1.0 1.0 1.0

The lateral group efficiency factor (Ge) can be approximately taken as the average value of the

Pm’s from Table 6-1 for all piles in the group as suggested by Duncan, Robinette and Mokwa

(2005). For instance, a 3 by 3 pile group with a center-to-center spacing of 3 widths, the lateral

6-4 Report No. 34979 group efficiency will be approximately 0.69 [=(0.82 + 0.68 + 0.58) /3]. Based on Table 6-1, the lateral group effects can be neglected for center-to-center pile/pier spacing of 6 widths or more.

There is commercially available software (e.g., GROUP by Ensoft) which can perform more refined lateral pile group response analyses, in particular for complex pile group configurations.

Such analyses should be performed on a case-by-case basis since it depends on the specific pile configuration, pile type and penetration, loading conditions, etc.

6.5 Pile Installation

Driven Piles

The following items are important to the successful completion of driven piles for this project.

Pile driving hammers should be selected according to pile type, length, size and weight of pile, as well as potential vibrations resulting from pile driving operations. Care should be taken to assure that the hammer selected is capable of achieving the desired penetration without causing damage to the piles or causing excessive vibrations which could damage existing, nearby structures.

Each pile should be driven to the desired tip elevation and driving resistance without interruption in the driving operations. Accurate records of the final tip elevation and driving resistances should be obtained during the pile driving operations. Monitoring of each pile driving record and hammer/cushion effects should be performed during pile installation.

Supplemental techniques such as jetting should not be required to reach the design pile tip elevation. If pile damage and/or refusal are encountered during pile driving operations, TWE should be contacted to evaluate pile capacity and provide recommendations on a case-by-case basis.

TWE could be retained to analyze drivability based on the final pile sizes, pile lengths and proposed driving system(s) and to develop pile driving criteria based on refined Wave Equation

Analyses as part of a pile load testing program including dynamic analyses on test piles.

The hammer type, cap, cushion block and driving energy should be planned to avoid pile damage during driving. The pile hammer should be sufficient to drive the piles to the lengths required without causing pile damage. Driving criteria should be established prior to installation based on the following criteria:

• Pile design load;

• Load test data, if available;

• Pile type and size;

• Type of hammer; and

• Type of cap and cushion block.

6-5 Report No. 34979

The driving of displacement piles can result in vertical heave and lateral displacement of adjacent piles. The tops of the piles should be checked after driving of adjacent piles. If heave has occurred, the piles should be re-driven to the original tip elevation. Where the displacement piles are installed in groups, heave and lateral displacement will be most critical. The contractor can reduce heave and displacement within a pile group by installing the interior piles first and then proceeding to the perimeter locations.

The piles should be properly-aligned prior to driving and held with fixed leads. Realignment, once driving has commenced, should not be allowed. The top of the pile should be square or perpendicular to the longitudinal axis of the pile to reduce damage to the pile edges during driving. It is common practice to specify a tolerance of 2% for the pile verticality and that the top of the pile be within 3-in or less of the specified location.

The entire hammer-cushion-pile system should be compatible and capable of installing piling to design penetrations in an undamaged condition. Adequate cushion material between the pile driving cap and the pile head should be provided. For piles over 20-ft in length, a cushion of soft wood with a thickness of 6-in to 12-in is preferred.

7-1 Report No. 34979

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 to a depth of at least 18-in below natural ground surface. Tree stumps shall be completely removed and backfilled. After stripping and tree removal and prior to new construction, the resulting excavations should be backfilled with non-expansive structural fill material and compacted according to the recommendations provided here-in. The top 18-in of native soils can be used for general fill purposes after all organic matter (roots, tree trunks, grass, weeds, etc.) has been removed.

Subgrades to receive fill soils should be proof rolled with at least a 20-ton pneumatic roller, loaded dump truck, or equivalent, to detect weak areas. Such weak areas should be removed and replaced with soils exhibiting similar classification, moisture content, and density as the adjacent in-place soils. Subsequent to proof rolling, and just prior to placement of select fill, the upper 6-in of the exposed subgrade should be compacted to at least 95% of the maximum dry density at a moisture near (0 to +4%) the optimum moisture in accordance with Standard Proctor (ASTM D 698) procedures.

Proper site drainage should be maintained during construction so that ponding of surface runoff does not occur and cause construction delays and/or inhibit site access. Due to the nature of the subgrade, the cohesive soils can become wet and soft. If the subgrade becomes wet and soft, consideration can be given to removal or replacement of the wet material with structural fill material.

The maximum loose thickness for each lift will depend on the type of compaction equipment used.

Recommended fill layers are summarized in Table 7-1 below.

Table 7-1: Compaction Equipment and Maximum Lift Thickness

Compaction Equipment Maximum Lift Thickness

Mechanical Hand Tamper 4.0-in

Pneumatic Tired Roller 6.0-in

Tamping Foot Roller 8.0-in

Sheepsfoot Roller 8.0-in

Non-expansive structural select fill material for this project should consist of a clean low-plasticity sandy clay (CL) or clayey sand (SC) material with a liquid limit of less than 40 and a plasticity index between 7 and 20. The select fill should be placed in thin lifts, not exceeding the maximum lift thickness of 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).

7-2 Report No. 34979

Prior to any filling operations, samples of the proposed fill 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

The performance of the foundation system for the proposed structures 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 structures does not occur. Accumulations of water near the structures could cause significant moisture variations in the soils adjacent to the foundations thus increasing the potential for structural distress and, thus, should be avoided.

8-1 Report No. 34979

8 DESIGN REVIEW AND LIMITATIONS

8.1 Design Review and Construction Monitoring

Geotechnical Design Review

Geotechnical review of the design drawings and specifications should be performed prior to construction. This review is recommended to check that the geotechnical recommendations and construction guidelines presented herein have been properly interpreted and incorporated into the construction documents.

Construction Monitoring

The performance of the foundations and pavements for this project will be highly dependent on the quality of construction. Thus, it is recommended that construction activities be monitored by an experienced laboratory proficient in quality control testing/inspection procedures. TWE would be pleased to assist in the development of a plan for construction monitoring to be incorporated in the overall quality control program.

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. Performance of the foundation system and pavements will be directly related to the Contractor’s adherence to the recommendations in this report and the project plans and specifications. Testing should be provided for all site preparation, foundation concrete pours, and pavement construction activities. TWE would be pleased to provide these services to verify that construction has been performed in accordance with the intentions of this report upon request.

8.2 Limitations

Scope of Study

The scope of this study, as well as the conclusions and recommendations provided herein, were developed based on our understanding of the project. Assumptions were made when specific information was unknown. Revisions to our conclusions and recommendations could be necessary as a result of any significant project changes or if our assumptions are incorrect. Construction dewatering design, earth retention design, and construction site safety are the responsibility of the

Contractor and have not been addressed herein. The scope of our study did not include evaluation of areal fill conditions or geologic faults. In addition, assessment of environmental conditions, including investigation for hazardous materials/pollutants/wastes, regulatory compliance, threatened or endangered species, cultural resources, floodplains, and jurisdictional wetlands were beyond the scope of our study.

Warranty

The professional services that form the basis for this report have been performed using that degree of care and skill ordinarily exercised, under similar circumstances, by reputable geotechnical engineers practicing in the same locality. No warranty, expressed or implied, is made as to the professional advice set forth.

8-2 Report No. 34979

Subsurface Variations

Our interpretations of subsurface conditions are based on data obtained at the boring locations only and at the time of our field exploration. Subsurface variations could exist between the boring locations and at areas not explored. The validity of our recommendations is based, in part, on assumptions made about subsurface conditions in areas not explored. Such assumptions can only be confirmed during construction. Therefore, construction observations by qualified geotechnical representatives are recommended to check for variations in subsurface conditions. Significant changes from our assumptions could require modification to our findings and recommendations.

Report Reliance

This report was prepared as an instrument of service for the sole and exclusive use by LJA

Engineering, Inc. subject to the limitations stated herein and with specific application to the referenced project. This report should not be applied for any other purpose or project, expect as described herein.

This report shall remain the property of Tolunay-Wong Engineers, Inc. No third party may use or rely upon the information provided herein without our express written consent. If any party other than LJA Engineering, Inc. chooses to rely on this instrument without our consent, said party expressly waives any rights it may otherwise have to claim its reliance on this instrument of professional service that resulted in injury, loss, or damage of any kind and will defend and indemnify Tolunay-Wong Engineers, Inc., from any such claim.

Report Distribution

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.

This geotechnical engineering report is intended to assist in the planning and design of the project and is neither appropriate nor intended for use as technical specifications. This report should not be incorporated into the construction documents either directly or by reference. We recommend the Client engage the services of a Design Engineer to perform final design of any site improvements and to prepare construction plans and specifications.

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.

APPENDIX A

SOIL BORING LOCATION PLAN

TWE DRAWING 24.53.069-1

Report No. 34974

APPENDIX B

SOIL BORING LOGS AND A

KEY TO TERMS AND SYMBOLS USED ON BORING LOGS

Report No. 34979

Very loose gray and tan POORLY GRADED SAND with CLAY (SP-SC)

-color changes to tan

-becomes medium dense

-becomes loose

-becomes medium dense and color changes to tan and gray

Medium dense tan nad gray CLAYEY SAND (SC)

-becomes loose and color changes to tan w/ shell fragments

-becomes medium dense

Medium dense tan POORLY GRADED SAND with

CLAY (SP SC)

-w/ shell fragments -becomes loose

Bottom @ 20'

W.O.H W.O.H

1/6"

1/6" 1/6" 1/6"

3/6" 5/6" 6/6"

3/6" 3/6" 2/6"

3/6" 5/6" 8/6"

4/6" 5/6" 7/6"

4/6" 4/6" 5/6"

4/6" 5/6" 6/6"

4/6" 5/6" 6/6"

3/6" 4/6" 6/6"

TOLUNAY-WONG ENGINEERS, INC.

LOG OF BORING B-1

PROJECT: Boardwalk Replacement AP

Aransas Pass, Tx CLIENT: LJA Engineering, Inc.

Katy, Tx

COMPLETION DEPTH: 20 ft NOTES: Groundwater encountered at a depth of about 1.5-ft while advancing the boring.

After 15 minutes, water level measured at a depth of 1.0-ft. Boring was terminated at 20.0-ft

DATE BORING STARTED: 8/9/2024

DATE BORING COMPLETED: 8/9/2024

LOGGER: Z.Hubbard PROJECT NO.: 24.53.069 Page 1 of 1

E L

E V

A T

IO

N

F

T

D E

P T

H

F T

S A

M P

L E

T Y

P E

R E

C O

V E

R Y

IN

S Y

M B

O L

MATERIAL DESCRIPTION

COORDINATES:

SURFACE ELEVATION:

DRILLING METHOD:

Dry Augered: to Wash Bored: to

(P

P O

C K

E T

P E

N ts f)

(T

T O

R V

A N

E ts f)

S T

D P

E N

E T

R A

T

IO

N T

E S

T B

L O

W C

O U

N T

M O

IS

T

U R

E C

O N

T E

N T

D R

Y U

N

IT

W E

IG

H

T (p cf

L

IQ

U

ID

L

IM

IT

P L

A S

T

IC

IT

Y

IN

D

E X

C O

M P

R E

S S

IV

E

S T

R E

N G

T H ts f)

F A

IL

U

R E

S T

R A

IN

C O

N F

IN

IN

G P

R E

S S

U R

E p si

P A

S S

IN

G

N o

S

IE

V E

O T

H E

R T

E S

T S

P E

R F

O R

M E

D

0' 20'

27° 53' 12.18" 97° 09' 09.59"

N W

BHarris Typewriter

NP

BHarris Typewriter

NP

Loose gray and tan CLAYEY SAND (SC)

-becomes medium dense and color changes to tan

Loose tan POORLY GRADED SAND with CLAY (SP-

SC)

-becomes medium dense

Medium dense tan and gray CLAYEY SAND (SC)

-color changes to tan

Medium dense tan POORLY GRADED SAND with

CLAY (SP-SC)

-color changes to loose

Bottom @ 20'

5/6' 5/6' 4/6'

3/6" 5/6" 6/6"

3/6' 4/6' 4/6"

5/6' 6/6" 6/6"

7/6" 8/6"

12/6"

11/6" 12/6" 13/6"

10/6" 12/6" 12/6"

8/6" 9/6" 6/6"

5/6" 5/6" 7/6"

2/6" 3/6" 5/6"

26 18

TOLUNAY-WONG ENGINEERS, INC.

LOG OF BORING B-2

PROJECT: Boardwalk Replacement AP

Aransas Pass, Tx CLIENT: LJA Engineering, Inc.

Katy, Tx

COMPLETION DEPTH: 20 ft NOTES: Groundwater encountered at a depth of about 5.0-ft while advancing the boring.

After 15 minutes, water level measured at a depth of 4.9-ft. Boring was terminated at 20.0-ft

DATE BORING STARTED: 8/9/2024

DATE BORING COMPLETED: 8/9/2024

LOGGER: Z.Hubbard PROJECT NO.: 24.53.069 Page 1 of 1

E L

E V

A T

IO

N

F

T

D E

P T

H

F T

S A

M P

L E

T Y

P E

R E

C O

V E

R Y

IN

S Y

M B

O L

MATERIAL DESCRIPTION

COORDINATES:

SURFACE ELEVATION:

DRILLING METHOD:

Dry Augered: to Wash Bored: to

(P

P O

C K

E T

P E

N ts f)

(T

T O

R V

A N

E ts f)

S T

D P

E N

E T

R A

T

IO

N T

E S

T B

L O

W C

O U

N T

M O

IS

T

U R

E C

O N

T E

N T

D R

Y U

N

IT

W E

IG

H

T (p cf

L

IQ

U

ID

L

IM

IT

P L

A S

T

IC

IT

Y

IN

D

E X

C O

M P

R E

S S

IV

E

S T

R E

N G

T H ts f)

F A

IL

U

R E

S T

R A

IN

C O

N F

IN

IN

G P

R E

S S

U R

E p si

P A

S S

IN

G

N o

S

IE

V E

O T

H E

R T

E S

T S

P E

R F

O R

M E

D

0' 20'

27° 53' 10.46" 97° 09' 08.97"

N W

Very loose gray and dark brown POORLY GRADED SAND with CLAY (SP-SC)

-color changes to gray brown and tan

Medium dense brown and gray CLAYEY SAND (SC)

-color changes to gray and tan

-becomes loose and color changes to gray and brown

-becomes medium dense

-becomes loose and color changes to tan

-becomes medium dense

Bottom @ 20'

W.O.H W.O.H

2/6"

W.O.H 2/6" 2/6"

4/6" 7/6" 5/6"

7/6" 5/6" 8/6"

5/6" 8/6" 9/6"

3/6" 5/6" 5/6"

4/6" 5/6" 6/6"

3/6" 3/6" 3/6"

7/6" 9/6"

11/6"

5/6" 7/6"

13/6"

30 13

TOLUNAY-WONG ENGINEERS, INC.

LOG OF BORING B-3

PROJECT: Boardwalk Replacement AP

Aransas Pass, Tx CLIENT: LJA Engineering, Inc.

Katy, Tx

COMPLETION DEPTH: 20 ft NOTES: Groundwater encountered at a depth of about 2.0-ft while advancing the boring.

After 15 minutes, water level measured at a depth of 1.8-ft. Boring was terminated at 20.0-ft

DATE BORING STARTED: 8/9/2024

DATE BORING COMPLETED: 8/9/2024

LOGGER: Z.Hubbard PROJECT NO.: 24.53.069 Page 1 of 1

E L

E V

A T

IO

N

F

T

D E

P T

H

F T

S A

M P

L E

T Y

P E

R E

C O

V E

R Y

IN

S Y

M B

O L

MATERIAL DESCRIPTION

COORDINATES:

SURFACE ELEVATION:

DRILLING METHOD:

Dry Augered: to Wash Bored: to

(P

P O

C K

E T

P E

N ts f)

(T

T O

R V

A N

E ts f)

S T

D P

E N

E T

R A

T

IO

N T

E S

T B

L O

W C

O U

N T

M O

IS

T

U R

E C

O N

T E

N T

D R

Y U

N

IT

W E

IG

H

T (p cf

L

IQ

U

ID

L

IM

IT

P L

A S

T

IC

IT

Y

IN

D

E X

C O

M P

R E

S S

IV

E

S T

R E

N G

T H ts f)

F A

IL

U

R E

S T

R A

IN

C O

N F

IN

IN

G P

R E

S S

U R

E p si

P A

S S

IN

G

N o

S

IE

V E

O T

H E

R T

E S

T S

P E

R F

O R

M E

D

0' 20'

27° 53' 08.96" 97° 09' 07.37"

N W

BHarris Typewriter

NP

BHarris Typewriter

NP

KEY TO SYMBOLS AND TERMS USED ON BORING LOGS FOR SOIL

Most Common Unified Soil Sampler Symbols Meaning

Classifications System Symbols

• 77

•f

\ A-,7'

/T .

7:

L

A/ ^ 7

Lean Clay (CL )

Lean Clay w/ Sand (CL)

Sandy Lean Clay (CL)

Fat Clay (CH)

Fat Clay w/ Sand (CH)

Sandy Fat Clay (CH)

Silty Clay (CL-ML)

Sandy Silty Clay (CL-ML)

Silty Clayey Sand (SC-SM)

Clayey Sand (SC)

Sandy Silt ( ML)

Silty Sand (SM)

Silt w/ Sand (ML )

*; ' V

" I /1 i :

s 1 i I *1 *1 « i i r

4^/. /•

Well Graded Sand (SW)

Well Graded Sand w/ Gravel ( SW-GM)

Poorly Graded Sand (SP)

Poorly Graded Sand w/ Silt (SP-SM)

Silt (ML)

Elastic Silt (MH)

Elastic Silt w/ Sand ( MH-SP)

Silty Gravel (GM )

Clayey Gravel ( GC)

Well Graded Gravel (GW)

Well Graded Gravel w/ Sand (SP-GM)

Poorly Graded Gravel (GP)

Peat

Miscellaneous Materials

Asphalt and/or BaseFill ' A : .

is ' ' A Concrete

Pavement core

Thin - walled tube sample

Standard Penetration Test (SPT)

Auger sample

Sampling attempt with no recovery

TxDOT Cone Penetrometer Test

Field Test Data

2.50 Pocket penetrometer reading in tons per square foot

(T)1.13 Torvane Measurement in tons per square foot

8/6" Blow count per 6 - in. interval of the Standard Penetration Test

37 Observed free water during drilling

^ Observed static water level

Laboratory Test Data

Wc (%) Moisture content in percent

Dens, (pcf) Dry unit weight in pounds per cubic foot Qu (tsf ) Unconfined compressive strength in tons per square foot m H I B M

UU (tsf ) Compressive strength under confining pressure in tons per square foot

Str. (%) Strain at failure in percent LL Liquid Limit in percent

PI Plasticity Index

#200 (%) Percent passing the No. 200 mesh sieve ( ) Confining pressure in pounds per square inch

* Slickensided failure ** Did not fail @ 15% strain

RELATIVE DENSITY OF

COHESIONLESS & SEMI-COHESIONLESS SOILS

The following descriptive terms for relative density apply to cohesionless soils such as gravels, silty sands, and sands as well as semi-cohesive and semi-cohesionless soils such as sandy silts, and clayey sands.

Relative Density

Very Loose Loose

Medium Dense Dense

Very Dense

Typical N60

Value Range*

0-4 5-10

11-30 31-50

Over 50

CONSISTENCY OF COHESIVE SOILS

The following descriptive terms for consistency apply to cohesive soils such as clays, sandy clays, and silty clays.

Typical Compressive Strength (tsf) qu< 0.25

0.25 < qu< 0.50

0.50 < qu< 1.00

1.00 < qu< 2.00

2.00 < qu< 4.00 qu > 4.00

Consistency

Very soft Soft Firm Stiff

Very Stiff Hard

Typical

SPT "N 60"

Value Range**

< 2 3-4 5-8 9-15

16-30 > 31

* N60 is the number of blows from a 140-lb weight having a free fall of 30-in. required to penetrate the final 12-in. of an 18-in.

sample interval, corrected for field procedure to an average energy ratio of 60% (Terzaghi, Peck, and Mesri, 1996).

** An "N 60" value of 31 or greater corresponds to a hard consistency.

The correlation of consistency with a typical SPT "NM" value range is approximate.

Tolunay-Wong # Engineers, Inc.

REVISION DATE 1-5-12

GEOSYSTEM

jsanchez Typewriter Pocket Penetrometer (tsf) pp< 0.50

0.50 < pp< 0.75

0.75 < pp< 1.50

1.50 < pp< 3.00

3.00 < pp< 4.50 pp > 4.50

APPENDIX C

ALLOWABLE AXIAL PILE

CAPACITY CURVES

Project

Client Allowable Axial Capacity versus Elevation

8" x 5" Southern Pine Timber Pile Katy, Texas

Appendix: C

Figure: 1

LJA Engineering, Inc.

Boardwalk Improvements/Replacement

Aransas Pass, Texas

0 5 10 15 20 25

D ep th B el o w E x is ti n

G ro u n d S u rf a ce

(f t)

Allowable Axial Capacity (kips)

ALLOWABLE AXIAL CAPACITY VERSUS DEPTH

8" x 5" SOUTHERN PINE TIMBER PILE

Timber Allowable Compression

Capacity ityTimber Allowable Tensile Capac

NOTES:

1) Center-to-center spacing of the piles should be at least three (3) times the pile diameter.

2) Allowable skin friction and end bearing capacities contain a factor of safety of 3 ural engineer should verify the pile material properties can withstand the dynamic stresses induced during drivi3) The struct ng as well as the static stresses induced during service.

Upper Exclusion Zone

Allowable Axial Capacity versus Elevation

10" x 6" Southern Pine Timber Pile Katy, Texas

Appendix: C

Figure: 2

LJA Engineering, Inc.

Boardwalk Improvements/Replacement

Aransas Pass, Texas

0 5 10 15 20 25

D ep th B el o w E x is ti n

G ro u n d S u rf

Allowable Axial Capacity (kips)

ALLOWABLE AXIAL CAPACITY VERSUS DEPTH

10" x 6" SOUTHERN PINE TIMBER PILE

Timber Allowable Compression

Capacity ityTimber Allowable Tensile Capac

NOTES:

1) Center-to-center spacing of the piles should be at least three (3) times the pile diameter.

2) Allowable skin friction and end bearing capacities contain a factor of safety of 3 ural engineer should verify the pile material properties can withstand the dynamic stresses induced during drivi3) The struct ng as well as the static stresses induced during service.

Upper Exclusion Zone

Allowable Axial Capacity versus Elevation

12" x 8" Southern Pine Timber Pile Katy, Texas

Appendix: C

Figure: 3

LJA Engineering, Inc.

Boardwalk Improvements/Replacement

Aransas Pass, Texas

0 5 10 15 20 25 30 35

D ep th B el o w E x is ti n

G ro u n d S u rf

Allowable Axial Capacity (kips)

ALLOWABLE AXIAL CAPACITY VERSUS DEPTH

12" x 8" SOUTHERN PINE TIMBER PILE

Timber Allowable Compression

Capacity yTimber Allowable Tensile Capacit

NOTES:

1) Center-to-center spacing of the piles should be at least three (3) times the pile diameter.

2) Allowable skin friction and end bearing capacities contain a factor of safety of 3 ural engineer should verify the pile material properties can withstand the dynamic stresses induced during drivi3) The struct ng as well as the static stresses induced during service.

Upper Exclusion Zone

APPENDIX D

LPILE SOIL DESIGN PARAMETERS

Top Bottom

Sand (Reese) 0 2 95 -- 25 225 --

Sand (Reese) 2 7 38 -- 35 125 --

Sand (Reese) 7 20 48 -- 37 125 --

Sand (Reese) 20 #N/A #N/A -- -- 125 --

Sand (Reese) #N/A #N/A #N/A -- -- #N/A --

Table: Lateral Analysis Soil Design Parameters

Friction Angle

Project Number: 24.53.069

Report Number: 34979

Appendix D

Figure 1

LPILE

Soil Type

Depth (ft)

Katy, Texas

LJA Engineering, Inc

Aransas Pass, Texas

Boardwalk Replacement

Lateral Analysis Soil Design Parameters

Effective Unit

Weight, γ'

(pcf)

Cohesion, c

(psf)

Static Lateral

Modulus, k

(pci)

Strain

Factor, ε50