4-Geotechnical Engineering Report (Rodney J Hall - Butterbean Beach) Flag Pole.pdf

Report Cover Page

Butterbean Beach Flagpole

Geotechnical Engineering Report

June 5, 2025 | Terracon Project No. ES255084

Prepared for:

Chatham County 124 Bull Street, Rm 430 Savannah, Georgia 31412

2201 Rowland Avenue Savannah, GA 31404

P (912) 629-4000 Terracon.com/Savannah

Facilities | Environmental | Geotechnical | Materials

Report Cover Letter to Sign

June 5, 2025

Chatham County 124 Bull Street, Rm 430 Savannah, Georgia 31412

Attn: Mr. Corey Harper P: (912) 660-7607 E: jharper@chathamcounty.org

Re: Geotechnical Engineering Report Butterbean Beach Flagpole Savannah, Georgia Terracon Project No. ES255084

Dear Mr. Harper:

We have completed the scope of Geotechnical Engineering services for the above referenced project in general accordance with Terracon Proposal No. PES255084 dated April 7, 2025. This report presents the findings of the subsurface exploration and provides geotechnical recommendations concerning earthwork and construction of the flagpole foundation.

We appreciate the opportunity to be of service to you on this project. If you have any questions concerning this report or if we may be of further service, please contact us.

Sincerely, Terracon

Micah Hatch, P.E. Guoming Lin, Ph.D., P.E., BC.GE.

Geotechnical Department Manager Senior Consultant

Geotechnical Engineering Report Butterbean Beach Flagpole | Savannah, Georgia June 5, 2025 | Terracon Project No. ES255084

Facilities | Environmental | Geotechnical | Materials i

Table of Contents

Report Summary ............................................................................................. ii Introduction Project Description Site Conditions Geotechnical Characterization

Subsurface Profile Groundwater Conditions

Geotechnical Overview Geotechnical Considerations

Earthwork Site Drainage Subgrade Preparation Fill Material Types Fill Placement and Compaction Requirements Earthwork Construction Considerations Construction Observation and Testing

Drilled Pier Foundations Drilled Pier Design Parameters Drilled Pier Lateral Loading Drilled Pier Construction Considerations

Seismic Site Class General Comments

Attachments

Exploration Plan and Procedures Exploration and Testing Results Supporting Information

Note: This report was originally delivered in a web-based format. For more interactive features, please view your project online at client.terracon.com.

Refer to each individual Attachment for a listing of contents.

http://client.terracon.com/ http://client.terracon.com/

June 5, 2025 | Terracon Project No. ES255084

Facilities | Environmental | Geotechnical | Materials ii

Report Summary

Topic Overview Statement 1

Project Description

The project includes the construction of a new 100-foot-tall flagpole to replace the existing flagpole at the site.

Geotechnical Characterization

The site consists of intermittent layers of loose to medium dense clayey and silty sands and soft to medium stiff sandy clays in the upper 24 feet below the ground surface (BGS). These layers are underlain by medium dense to very dense silty and clean sands to CPT refusal depth of 38.7 feet BGS. A more detailed soil stratification is discussed in detail in Geotechnical Characterization.

Groundwater was encountered from 4.7 to 5.2 feet BGS during our field exploration.

Earthwork

■ Level and densify subgrade during subgrade preparation. If any soft/weak areas are detected during testing, repair subgrade by undercut and backfill.

■ For details, please refer to the Earthwork section.

Drilled Pier Foundations

■ The upper soils encountered at the CPT sounding are relatively weak. We recommend a drilled pier foundation bearing in medium dense/dense sand at least 18 feet BGS to support the flagpole.

■ Expected settlements: < 1-inch total

Seismic Considerations

For seismic design purposes, the subject site is classified as Site Class D in accordance with the International Building Code (IBC) 2018 and ASCE 7-16 Section 11.4.2.

General Comments

This section contains important information about the limitations of this geotechnical engineering report.

1. This summary is for convenience only. It should be used in conjunction with the entire report for design purposes.

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Introduction

This report presents the results of our subsurface exploration and Geotechnical Engineering services performed for the proposed flagpole to be located at Butterbean Beach at 45 Diamond Causeway in Savannah, Georgia. The purpose of these services was to provide information and geotechnical engineering recommendations relative to:

■ Subsurface soil conditions

■ Groundwater conditions

■ Seismic site classification per IBC

■ Site preparation and earthwork

■ Foundation options and engineering design parameters

The geotechnical engineering Scope of Services for this project included the advancement of one Cone Penetrometer Test (CPT) sounding to a maximum depth of 38.7 feet below the existing site grade (BGS, termination depths) and one Hand Auger boring to a maximum depth of 5 feet BGS.

Drawings showing the site and boring locations are shown in the Exploration Plan and Procedures section of this report. The results of the field exploration are included in the Exploration and Testing Results section of this report.

Project Description

Our initial understanding of the project was provided in our proposal and was discussed during project planning. A period of collaboration has transpired since the project was initiated, and our final understanding of the project conditions is as follows:

Item Description

Information Provided

Project information including the flagpole location and details were provided by Corey Harper with Chatham County via phone on March 24, 2025 and subsequent emails.

Project Description

The project includes the construction of a new 100-foot-tall flagpole to replace the existing flagpole at the site.

Proposed Structures

The proposed project will include the construction of foundation to support the new flagpole.

Finished Grade Elevation

Match existing.

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Item Description

Maximum Loads Based on our understanding of the project, we have assumed that wind loads will control the foundation design. Actual loads have not been provided at the time of this report.

Terracon should be notified if any of the above information is inconsistent with the planned construction, especially the grading limits, as modifications to our recommendations may be necessary.

Site Conditions

The following description of site conditions is derived from our site visit in association with the field exploration and our review of publicly available geologic and topographic maps.

Item Description

Parcel Information

The project is located at Butterbean Beach at 45 Diamond Causeway in Savannah, Georgia.

Latitude: 32.9481°, Longitude: -81.0677° (See Site Location)

Existing Improvements

There is an existing flagpole and landscaped area at the site.

Current Ground Cover

Landscaped/grass-covered areas.

Existing Topography

Relatively level.

Geotechnical Characterization

Subsurface Profile

We have developed a general characterization of the subsurface conditions based upon our review of the data and our understanding of the planned construction. The geotechnical characterization forms the basis of our geotechnical calculations and evaluation of the site preparation options. The following tables provide our geotechnical characterization.

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Facilities | Environmental | Geotechnical | Materials 3

Stratum Approximate Depth to Bottom of Stratum (feet)

Material Description Consistency/

Relative Density

1 10 Interbedded

Silty/Clayey Sand and Sandy Clay

Loose to Medium Dense (sands)

Soft to Medium Stiff (clays)

2 18 Sandy Clay/Clay Very soft to Soft

3 24 Interbedded

Silty/Clayey Sand and Sandy Clay

Loose to Medium Dense (sands)

Medium Stiff (clays)

38.7, maximum termination depth of CPT soundings

Sand with varying amounts of silt

Medium Dense to Very Dense

Conditions observed at each exploration point across the site are indicated on the individual logs shown in the Exploration and Testing Results section of this report.

Stratification boundaries on the CPT sounding log represent the approximate location of changes in native soil types; in situ, the transition between materials may be gradual.

Groundwater Conditions

The boreholes were observed while drilling and after completion for the presence and level of groundwater. The groundwater was measured at a depth of approximately 4.7 to 5.2 feet BGS during field exploration. The water levels observed in the boreholes can be found on logs in the Exploration and Testing Results section of this report and are summarized below.

Boring Label Measured Groundwater Depth (ft) C01 5.2

HA01 4.7

It is important to note; Groundwater conditions may change because of seasonal variations in rainfall, runoff, and other conditions not apparent at the time the borings were performed. The possibility of groundwater level fluctuations should be considered when developing the design and construction plans for the project. A positive site drainage plan is critical to site stability. The groundwater table should be checked prior to construction to assess its effect on sitework and other construction activities.

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Geotechnical Overview

The following evaluation and recommendations are based upon our understanding of the proposed construction and the results from our field exploration. If the above-described project conditions are incorrect or changed after this report, or subsurface conditions encountered during construction are significantly different from those reported, Terracon should be notified so we can re-evaluate our recommendations and make appropriate revisions.

Geotechnical Considerations

The subsurface conditions are considered adaptable for the proposed construction. The generalized soil profile is presented in the Geotechnical Characterization section.

Based on our understanding of the project, we have assumed wind loads will control the design of the flagpole foundation.

We performed settlement and bearing capacity analysis at the sounding location using the soil parameters derived from the CPT soundings and assumed structural loads. Based on the analysis results, we recommend a drilled pier foundation to support the flagpole. The upper soils are weak, and we recommend the drilled pier be installed into the sand layer a minimum of 18 feet BGS.

If the structural or load conditions are significantly different from those used in our evaluation and during construction, if the subsurface conditions are significantly different from those presented in this report, Terracon should be retained to perform additional evaluation and revise the recommendations, as well as provide testing and inspection during construction.

The recommendations contained in this report are based upon the results of field studies, engineering analyses, and our current understanding of the proposed project.

The General Comments section provides an understanding of the report limitations.

Earthwork

Earthwork is anticipated to include subgrade preparation, densification and installation of a site drainage system. The site work conditions will be dependent on the weather conditions and the contractor’s means and methods in controlling surface drainage and protecting the subgrade.

The following sections provide recommendations for use in the preparation of specifications for the work.

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Site Drainage

An effective drainage system should be installed prior to the initiation of site preparation and grading activities to intercept surface water and to improve overall shallow drainage.

The site should be graded to shed water and avoid ponding over the subgrade.

Subgrade Preparation

If weak soils are encountered at the proposed subgrade level, we recommend subgrade improvement with undercut and backfill. Additional undercut and backfill may be necessary to achieve a stable subgrade. The foundation work should be scheduled in consideration of the weather to avoid exposing the subgrade to excessive rains.

During site preparation, all structures should bear on suitable natural soil or on properly compacted structural fills. Compacted fill should be placed directly on suitable natural soil. We recommend Terracon be retained to test the subgrade during construction so that Terracon can provide additional recommendations to prepare the subgrade based on the conditions uncovered during the excavation.

Fill Material Types

If necessary for grading, any fill required should be classified as structural fill. Earthen materials used for structural fill should meet the following material property requirements

Soil Type 1 USCS Classification

Acceptable Parameters (for Structural Fill)

Granular

GW, GP, GM, GC,

SW, SP, SM, SC

Less than 25% passing No. 200 sieve

1. Structural fill should consist of approved materials free of organic matter and debris. A sample of each material type should be submitted to the Geotechnical Engineer for evaluation prior to use on this site.

Based on the findings from our CPT soundings and Hand Auger borings, the subject site consists of mostly clayey sands and sandy clays in the upper 10 feet BGS. These materials are generally considered moisture sensitive and are not recommended for use as structural fill.

Fill Placement and Compaction Requirements

Structural fill should meet the following compaction requirements.

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Item Structural Fill

Maximum Lift Thickness

8 inches or less in loose thickness when heavy, self-propelled compaction equipment is used 4 to 6 inches in loose thickness when hand-guided equipment (i.e., jumping jack or plate compactor) is used

Minimum Compaction

Requirements 1 95% of maximum

Water Content

Range 1 Granular: -3% to +3% of optimum

1. Maximum density and optimum water content as determined by the modified Proctor test (ASTM D 1557).

Earthwork Construction Considerations

Excavations are anticipated to be accomplished with conventional construction equipment.

Upon completion of filling and grading, care should be taken to maintain the subgrade water content during construction. Construction traffic over the completed subgrades should be avoided. The site should also be graded to prevent ponding of surface water on the prepared subgrades or in excavations. Water collecting over, or adjacent to, construction areas should be removed.

If the subgrade saturates or is disturbed, the affected material should be removed, or the materials should be scarified, moisture conditioned, and recompacted, prior to surface construction. The groundwater table could affect over-excavation efforts, especially for over-excavation and replacement of lower strength soils. A temporary dewatering system consisting of sumps with pumps could be necessary to achieve the recommended depth of over-excavation.

As a minimum, excavations should be performed in accordance with OSHA 29 CFR, Part 1926, Subpart P, “Excavations” and its appendices, and in accordance with any applicable local, and/or state regulations. Construction site safety is the sole responsibility of the contractor who controls the means, methods, and sequencing of construction operations.

Under no circumstances shall the information provided herein be interpreted to mean Terracon is assuming responsibility for construction site safety, or the contractor's activities; such responsibility shall neither be implied nor inferred.

Construction Observation and Testing

The earthwork efforts should be monitored under the direction of the Geotechnical Engineer. Monitoring should include bearing capacity evaluation in the field using hand auger borings and DCPs and mitigation of areas delineated by the onsite representative.

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Each lift of compacted fill should be tested, evaluated, and reworked, as necessary, until approved by the Geotechnical Engineer prior to placement of additional lifts. Each lift of fill should be tested for density and water content at a frequency provided by the project plan and specifications. In areas of foundation excavations, the bearing subgrade should be evaluated under the direction of the Geotechnical Engineer. If unanticipated conditions are encountered, the Geotechnical Engineer should prescribe mitigation options.

In addition to the documentation of the essential parameters necessary for construction, the continuation of the Geotechnical Engineer into the construction phase of the project provides the continuity to maintain the Geotechnical Engineer’s evaluation of subsurface conditions, including assessing variations and associated design changes.

Drilled Pier Foundations

Drilled Pier Design Parameters

Based on provided information, we understand a drilled pier foundation system could be used for the flagpole. Soil design parameters are provided below in the Drilled Pier Design Summary table for the design of drilled pier foundations. The values presented for allowable side friction and end bearing include a factor of safety of 2. The allowable side shear and end bearing were calculated based on sounding C01 using the FHWA Method (ref. FHWA, 1999).

Drilled Pier Design Summary 1

Depth

(Feet-bgs)

Stratigraphy Allowable Side Shear

(psf) 2

Allowable End Bearing

Pressure

(psf) Material

5 – 10 Clayey Sand/Sandy Clay 250 1,500

10 – 18 Sandy Clay 125 --3

18 – 25 Silty/Clayey Sand 350 6,000

25-38 Sand 700 12,000

1. Design capacities are dependent upon the method of installation and quality control parameters. The values provided are estimates and should be verified when installation protocol have been finalized.

2. Applicable for compressive loading only. Reduce to 2/3 of values shown for uplift loading. The effective weight of the shaft can be added to uplift load resistance to the extent permitted by IBC.

3. Not a recommended bearing layer.

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Piers should be adequately reinforced as designed by the Structural Engineer for both tension and shear to sufficient depths. Buoyant unit weights of the soil and concrete should be used in the calculations below the highest anticipated groundwater elevation.

A minimum shaft diameter of 30 inches should be used. Drilled piers should have a minimum length of 18 feet. Post-construction settlements of drilled shafts designed and constructed as described in this report are estimated to be less than about 1 inch.

Drilled Pier Lateral Loading

The following table lists input values for use in LPILE analyses. Such analysis should be considered if lateral loads are anticipated. Modern versions of LPILE provide estimated default values of kh and E50 based on strength and are recommended for the project. Since deflection or a service limit criterion will most likely control lateral capacity design, no safety/resistance factor is included with the parameters.

Stratigraphy1 L-Pile Soil Model

Su

(psf)2 2

(pcf)2 ε50 K (pci)

Elevation Material Static Cyclic

0 – 10 Sand Sand (Reese) -- 29 110 Use Default Value

10 – 18 Clay Stiff Clay with Free

Water 250 -- 42.6 Use Default Value

18 - 25 Sand Sand (Reese) -- 31 52.6 Use Default Value

25 - 38 Sand Sand (Reese) -- 34 57.6 Use Default Value

1. See Subsurface Profile in Geotechnical Characterization for more details on Stratigraphy.

2. Definition of Terms:

Su: Undrained shear strength : Internal friction angle ’: Effective unit weight

Drilled Pier Construction Considerations

The drilling contractor should be experienced in the subsurface conditions observed at the site, and the excavations should be performed with equipment capable of providing a clean bearing surface. The drilled straight-shaft foundation system should be installed in general accordance with the procedures presented in "Standard Specification for the Construction of Drilled Piers", ACI Publication No. 336.1-01.

To prevent collapse of the sidewalls and/or to control groundwater seepage, the use of temporary steel casing and/or slurry drilling procedures may be required for construction

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Facilities | Environmental | Geotechnical | Materials 9 of the drilled pier foundation. Significant seepage could occur in the case of excavations penetrating water-bearing sandy soil. The contractor and foundation design engineer should be informed of these risks.

Care should be taken to not disturb the sides and bottom of the excavation during construction. The bottom of the shaft excavation should be free of loose material before concrete placement. Concrete should be placed as soon as possible after the foundation excavation is completed, to reduce potential disturbance of the bearing surface.

While withdrawing casing (if used), care should be exercised to maintain concrete inside the casing at a sufficient level to resist earth and hydrostatic pressures acting on the casing exterior. Arching of the concrete, loss of seal and other problems can occur during casing removal and result in contamination of the drilled pier. These conditions should be considered during the design and construction phases. Placement of loose soil backfill should not be permitted around the casing prior to removal.

The drilled shaft installation process should be performed under the observation of the Geotechnical Engineer. The Geotechnical Engineer should document the shaft installation process including soil and groundwater conditions observed, consistency with expected conditions, and details of the installed pier.

Seismic Site Class

The seismic design requirements for buildings and other structures are based on Seismic According to the International Building Code (IBC) 2018 and ASCE 7-16, structures should be designed and constructed to withstand the effects of earthquakes and avoid failure during a maximum considered earthquake. The maximum considered earthquake (MCE) is a seismic event that has a 50-year exposure period with a 2% probability of exceedance.

The 2,500-year earthquake has a Moment Magnitude (Mw) of 7.3 and a Site Class Adjusted Peak Ground Acceleration (PGAM) of 0.219 as determined by data provided by the IBC 2018 and ASCE 7-16 Standards.

Based on our findings from the field exploration and our knowledge of the local geological formation in the project area, the site can be classified as Site Class D in accordance with International Building Code (IBC) 2018 and ASCE 7-16. The seismic design parameters obtained based on IBC2018 and ASCE 7-16 are summarized in the table below.

The design response spectrum curve, as presented in the Supporting Information section, was developed based on the SDS and SD1 values according to IBC2018 and ASCE 7-16.

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Site Location

(Lat., Long.)

Site

Classification Ss S1 Fa Fv SDS SD1

31.9481°, -81.0677° D 0.292g 0.109g 1.566 2.383 0.305g 0.172g

■ In accordance with the 2018 International Building Code and ASCE 7-16.

■ The 2018 IBC and ASCE 7-16 require a site soil profile determination extending a depth of 100 feet for seismic site classification. The current scope does not include 100-foot soil profile determination. Explorations for this project extended to a maximum depth of 38.7 feet BGS, and this seismic site class definition was provided in consideration of the overall soil conditions as well as the general geology of the area.

General Comments

Our analysis and opinions are based upon our understanding of the project, the geotechnical conditions in the area, and the data obtained from our site exploration.

Variations will occur between exploration point locations or due to the modifying effects of construction or weather. The nature and extent of such variations may not become evident until during or after construction.

Terracon should be retained as the Geotechnical Engineer, where noted in this report, to provide observation and testing services during pertinent construction phases. If variations appear, we can provide further evaluation and supplemental recommendations.

If variations are noted in the absence of our observation and testing services on-site, we should be immediately notified so that we can provide evaluation and supplemental recommendations.

Our Scope of Services does not include either specifically or by implication any environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials, or conditions. If the owner is concerned about the potential for such contamination or pollution, other studies should be undertaken.

Our services and any correspondence are intended for the sole benefit and exclusive use of our client for specific application to the project discussed and are accomplished in accordance with generally accepted geotechnical engineering practices with no third-party beneficiaries intended.

Any third-party access to services or correspondence is solely for information purposes to support the services provided by Terracon to our client. Reliance upon the services and

June 5, 2025 | Terracon Project No. ES255084

Facilities | Environmental | Geotechnical | Materials 11 any work product is limited to our client and is not intended for third parties. Any use or reliance of the provided information by third parties is done solely at their own risk. No warranties, either express or implied, are intended or made.

Site characteristics as provided are for design purposes and not to estimate excavation cost. Any use of our report in that regard is done at the sole risk of the excavating cost estimator as there may be variations on the site that are not apparent in the data that could significantly affect excavation cost.

Any parties charged with estimating excavation costs should seek their own site characterization for specific purposes to obtain the specific level of detail necessary for costing. Site safety and cost estimating including excavation support and dewatering requirements/design are the responsibility of others. Construction and site development have the potential to affect adjacent properties. Such impacts can include damages due to vibration, modification of groundwater/surface water flow during construction, foundation movement due to undermining or subsidence from excavation, as well as noise or air quality concerns. Evaluation of these items on nearby properties are commonly associated with contractor means and methods and are not addressed in this report. The owner and contractor should consider a preconstruction/precondition survey of surrounding development. If changes in the nature, design, or location of the project are planned, our conclusions and recommendations shall not be considered valid unless we review the changes and either verify or modify our conclusions in writing.

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Facilities | Environmental | Geotechnical | Materials

Attachments

June 5, 2025 | Terracon Project No. ES255084

Facilities | Environmental | Geotechnical | Materials

Exploration and Testing Procedures

Field Exploration

Number of Borings

Type of Exploration Approximate

Boring Depth (feet) Location

Cone Penetration Test

(CPT) Sounding 38.7

Flagpole foundation area

1 Hand Auger (HA) Boring 5

Boring Layout and Elevations: Terracon personnel provided the boring layout using handheld GPS equipment (estimated horizontal accuracy of about ±10 feet) and referencing existing site features.

Subsurface Exploration Procedures: We pushed the CPT sounding with a track-mounted drill rig. CPT sounding is the technology in which an electronically instrumented cone penetrometer is hydraulically pushed through the soil while nearly continuous readings are recorded to a portable computer. The cone is equipped with electronic load cells to measure tip resistance and sleeve resistance and a pressure transducer to measure the generated ambient pore pressure. The face of the cone has an apex angle of 60° and an area of 15 cm2. Digital data representing the tip resistance, friction resistance, pore water pressure, and probe inclination angle are recorded about every 2 centimeters while advancing through the ground at a rate between 1½ and 2½ centimeters per second.

These measurements are correlated to various soil properties used for geotechnical design. No soil samples are gathered through this subsurface investigation technique.

CPT testing was conducted in general accordance with ASTM D5778, Standard Test Method for Performing Electronic Friction Cone and Piezocone Penetration Testing of Soils. Upon completion, the CPT data collected was analyzed and processed by the project engineer.

Hand auger borings were conducted in general accordance with ASTM D1452 to determine the subsurface conditions at shallow depths. In this test, the hand auger boring is drilled by rotating and advancing a bucket auger to the desired depths while periodically removing the auger from the hole to clear and examine the auger cuttings. The soils will be visually classified by a geotechnical engineer or geologist in accordance with ASTM D2488.

We also observed the boreholes while drilling and at the completion of drilling for the presence of groundwater. The groundwater level is shown on the attached boring logs.

For safety purposes, all borings were backfilled with auger cuttings after their completion.

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The sampling depths, penetration distances, and other sampling information was recorded on the field boring logs. The samples were placed in appropriate containers and taken to our soil laboratory for testing and classification by a Geotechnical Engineer. Our exploration team prepared field boring logs as part of the drilling operations. These field logs included visual classifications of the materials observed during drilling and our interpretation of the subsurface conditions between samples. Final boring logs were prepared from the field logs. The final boring logs represent the Geotechnical Engineer's interpretation of the field logs and include modifications based on observations and tests of the samples in our laboratory.

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Site Location and Exploration Plans

Contents:

Site Location Plan Exploration Plan

Note: All attachments are one page unless noted above.

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Site Location

DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY GOOGLE EARTH MAPS

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Exploration Plan

DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY GOOGLE EARTH MAPS

Exploration Results

Contents:

CPT Sounding Log Hand Auger Log

Depth (ft)

Depth (ft)

CPT Sounding ID C01

5 10 15 20

Tip Resistance, qt (tsf)

50 100 150 200

Facilities | Environmental | Geotechnical | Materials

Friction Ratio, Fr

0.8 1.6 2.4 3.2

Sleeve Friction, fs (tsf)

0.5 1.0 1.5 2.0

0.05 0.10 0.15 0.20 Material Description

Normalized CPT Soil Behavior Type

1 2 3 4 5 6 7 8

Pore Pressure, u2 (tsf)

0 1 2 3

Hydrostatic Pressure

CPT Terminated at 38.7 Feet

1 Sensitive, fine grained

Normalized Soil Behavior Type (Robertson 1990)

Water Level ObservationSee Exploration and Testing Procedures for a description of field and laboratory procedures used and additional data, if any.

See Supporting Information for explanation of symbols and abbreviations. (used in normalizations and correlations)

Butterbean Beach Flagpole

45 Diamond Causeway | Savannah, GA

Notes

Test Location: See Exploration Plan

5.2 ft measured water depth

CPT Equipment

Terracon Project No. ES255084

Savannah, GA

2201 Rowland Ave

3 Clay - silty clay to clay

2 Organic soils - clay

CPT sensor calibration reports available upon request

Probe No. 5625 with net area ratio of .847

U2 pore pressure transducer location

Manufactured by Geotech A.B.- Calibrated 4/6/2022

Tip and sleeve areas of 15 cm2 and 225 cm2

None friction reducer

Latitude: 31.9481° Longitude: -81.0677°

CPT Completed: 5/7/2025

CPT Started: 5/7/2025

9 Very stiff fine grained

4 Silt mixtures - clayey silt to silty clay

8 Very stiff sand to clayey sand

7 Gravelly sand to dense sand

6 Sands - clean sand to silty sand

5 Sand mixtures - silty sand to sandy silt

Operator: ARS

CPT Rig: Geoprobe

Depth (ft)

Depth (ft)

See CPT Sounding ID C01 for Detailed Test Results

CPT Correlative Parameter Sounding ID C01

5 10 15 20 Tip Resistance, qt

(tsf)

50 100 150 200

Facilities | Environmental | Geotechnical | MaterialsThis boring log is not valid if separated from original report.

Hydrostatic Pressure

Pore Pressure, u2 (tsf)

0 1 2 3

Material Description

Normalized CPT Soil Behavior Type

1 2 3 4 5 6 7 8

0.05 0.10 0.15 0.20 Sleeve Friction, fs

(tsf)

0.5 1.0 1.5 2.0

Friction Ratio, Fr

1 2 3

N60 Value

10 20 30 40

N60 Value

1 2 3 4

CPT Terminated at 38.7 Feet

Notes

Butterbean Beach Flagpole

45 Diamond Causeway | Savannah, GA

Terracon Project No. ES255084

(used in normalizations and correlations)

Water Level Observation

Normalized Soil Behavior Type (Robertson 1990)

5.2 ft measured water depth

See Exploration and Testing Procedures for a description of field and laboratory procedures used and additional data (If any).

See Supporting Information for explanation of symbols and abbreviations.

Test Location: See Exploration Plan

Latitude: 31.9481° Longitude: -81.0677°

7 Gravelly sand to dense sand 8 Very stiff sand to clayey sand 9 Very stiff fine grained

CPT Rig:

Geoprobe

Operator:

ARS

4 Silt mixtures - clayey silt to silty clay 5 Sand mixtures - silty sand to sandy silt 6 Sands - clean sand to silty sand

1 Sensitive, fine grained 2 Organic soils - clay 3 Clay - silty clay to clay

CPT Completed: 5/7/2025 CPT Started: 5/7/2025

2201 Rowland Ave Savannah, GA

Penetrometer Parameters

CPT sensor calibration reports available upon request.

Probe No. 5625 with net area ratio of .847

U2 pore pressure transducer location

Manufactured by Geotech A.B.; calibrated 4/6/2022

Tip and sleeve areas of 15 cm2 and 225 cm2

None friction reducer

TOPSOIL

CLAYEY SAND (SC), fine to medium grained, light brown/orange, moist

SANDY LEAN CLAY (CL), with shells, contains roots, gray/brown/orange, moist

SANDY LEAN CLAY (CL), with shells, contains sand lenses, light gray/orange/brown, moist to wet

Boring Terminated at 5 Feet

Boring Log No. HA01

W at er L ev el

O bs er va tio ns

D ep th

Ft

Facilities | Environmental | Geotechnical | Materials

G ra p h ic

L o g

0.5

2.3

3.3

5.0

Abandonment Method Boring backfilled with auger cuttings upon completion.

Advancement Method Manual Hand Auger

Driller

MM

Logged by

TV

Boring Started 04-28-2025

Boring Completed 04-28-2025

2201 Rowland Ave

Drill Rig Hand Auger

Butterbean Beach Flagpole

Savannah, GA

45 Diamond Causeway | Savannah, GA

Terracon Project No. ES255084

See Exploration and Testing Procedures for a description of field and laboratory procedures used and additional data (If any).

See Supporting Information for explanation of symbols and abbreviations.

Notes

Water Level Observations

Groundwater encountered at 4.7' BGS

S am pl e

T yp eSee Exploration PlanLocation:

Latitude: 31.9481° Longitude: -81.0677°

Depth (Ft.)

Supporting Information

Contents:

General Notes Unified Soil Classification System CPT General Notes Seismic Design Parameters

Ring Sampler

S A

M P

L

IN

G

G R

O U

N D

W A

T E

R

Groundwater Initially Encountered

(More than 50% retained on No. 200 sieve.)

Density determined by Standard Penetration Resistance

Includes gravels, sands and silts.

Boulders Cobbles Gravel Sand Silt or Clay

Auger Split Spoon

No Recovery Rock Core

Shelby Tube Macro Core

F

IE

L D

T E

S T

S

PLASTICITY DESCRIPTION

Term

Hand Penetrometer

Torvane

Standard Penetration Test (blows per foot)

Photo-Ionization Detector

Organic Vapor Analyzer

Groundwater Level After a Specified Period of Time

Static Groundwater Level After a Specified Period of Time

Unless otherwise noted, Latitude and Longitude are approximately determined using a hand-held GPS device. The accuracy of such devices is variable. Surface elevation data annotated with +/- indicates that no actual topographical survey was conducted to confirm the surface elevation. Instead, the surface elevation was approximately determined from topographic maps of the area.

Non-plastic Low Medium High

Soil classification is based on the Unified Soil Classification System. Coarse Grained Soils have more than 50% of their dry weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand. Fine Grained Soils have less than 50% of their dry weight retained on a #200 sieve; they are principally described as clays if they are plastic, and silts if they are slightly plastic or non-plastic. Major constituents may be added as modifiers and minor constituents may be added according to the relative proportions based on grain size. In addition to gradation, coarse-grained soils are defined on the basis of their in-place relative density and fine-grained soils on the basis of their consistency.

Plasticity Index

1 - 10 11 - 30

> 30

RELATIVE PROPORTIONS OF FINES

Descriptive Term(s) of other constituents Percent of Dry Weight

< 5 5 - 12 > 12

Trace With Modifier

RELATIVE PROPORTIONS OF SAND AND GRAVEL GRAIN SIZE TERMINOLOGY

Hard

Trace With Modifier above 4.00 > 30

2.00 to 4.00

1.00 to 2.00

0.50 to 1.00

0.25 to 0.50 less than 0.25

(50% or more passing the No. 200 sieve.)

Consistency determined by laboratory shear strength testing, field visual-manual procedures or standard penetration resistance

CONSISTENCY OF FINE-GRAINED SOILS

Very Loose

Loose

Medium Dense

Dense

Descriptive Term (Density)

> 50

30 - 50

10 - 29

4 - 9

0 - 3

S T

R E

N G

T H

T E

R M

S Std. Penetration Resistance (blows per foot)

Very Stiff

Stiff

RELATIVE DENSITY OF COARSE-GRAINED SOILS

15 - 30

8 - 14

Medium-Stiff

Soft

Very Soft

Descriptive Term (Consistency)

2 - 4

0 - 1

Std. Penetration Resistance (blows per foot)

Undrained Shear Strength (kips per square foot)

Very Dense

5 - 7

Over 12 in. (300 mm) 12 in. to 3 in. (300mm to 75mm)

3 in. to #4 sieve (75mm to 4.75 mm) #4 to #200 sieve (4.75mm to 0.075mm

Passing #200 sieve (0.075mm)

< 15 15 - 29 > 30

Descriptive Term(s) of other constituents

Percent of Dry Weight

Descriptive Term(s) of other constituents

Percent of Dry Weight

No Groundwater Observed

GENERAL NOTES

LOCATION AND ELEVATION NOTES

(HP)

(T)

(b/f)

(PID)

(OVA)

Water levels indicated on the soil boring logs are the levels measured in the borehole at the times indicated.

Groundwater level variations will occur over time. In low permeability soils, accurate determination of groundwater levels is not possible with short term water level observations.

DESCRIPTION OF SYMBOLS AND ABBREVIATIONS

DESCRIPTIVE SOIL CLASSIFICATION

June 5, 2025 | Terracon Project No. ES255084

Facilities | Environmental | Geotechnical | Materials

Unified Soil Classification System Criteria for Assigning Group Symbols and Group Names Using

Laboratory Tests A

Soil Classification Group

Symbol Group Name B

Coarse-Grained Soils:

More than 50% retained on No. 200 sieve

Gravels:

More than 50% of coarse fraction retained on No. 4 sieve

Clean Gravels:

Less than 5% fines C

Cu≥4 and 1≤Cc≤3 E GW Well-graded gravel F

Cu<4 and/or [Cc<1 or Cc>3.0] E GP Poorly graded gravel F

Gravels with Fines:

More than 12% fines C

Fines classify as ML or MH GM Silty gravel F, G, H

Fines classify as CL or CH GC Clayey gravel F, G, H

Sands:

50% or more of coarse fraction passes No. 4 sieve

Clean Sands:

Less than 5% fines D

Cu≥6 and 1≤Cc≤3 E SW Well-graded sand I

Cu<6 and/or [Cc<1 or Cc>3.0] E SP Poorly graded sand I

Sands with Fines:

More than 12% fines D

Fines classify as ML or MH SM Silty sand G, H, I

Fines classify as CL or CH SC Clayey sand G, H, I

Fine-Grained Soils:

50% or more passes the

No. 200 sieve

Silts and Clays:

Liquid limit less than

Inorganic:

PI > 7 and plots above “A” line J CL Lean clay K, L, M

PI < 4 or plots below “A” line J ML Silt K, L, M

Organic:

𝐿𝐿 𝑜𝑣𝑒𝑛 𝑑𝑟𝑖𝑒𝑑

𝐿𝐿 𝑛𝑜𝑡 𝑑𝑟𝑖𝑒𝑑

< 0.75 OL

Organic clay K, L, M, N

Organic silt K, L, M, O

Silts and Clays:

Liquid limit 50 or more

Inorganic:

PI plots on or above “A” line CH Fat clay K, L, M

PI plots below “A” line MH Elastic silt K, L, M

Organic:

𝐿𝐿 𝑜𝑣𝑒𝑛 𝑑𝑟𝑖𝑒𝑑

𝐿𝐿 𝑛𝑜𝑡 𝑑𝑟𝑖𝑒𝑑

< 0.75 OH

Organic clay K, L, M, P

Organic silt K, L, M, Q

Highly organic soils: Primarily organic matter, dark in color, and organic odor PT Peat A Based on the material passing the 3-inch (75-mm) sieve.

B If field sample contained cobbles or boulders, or both, add “with cobbles or boulders, or both” to group name.

C Gravels with 5 to 12% fines require dual symbols: GW-GM well-graded gravel with silt, GW-GC well-graded gravel with clay, GP-GM poorly graded gravel with silt, GP-GC poorly graded gravel with clay.

D Sands with 5 to 12% fines require dual symbols: SW-SM well-graded sand with silt, SW-SC well-graded sand with clay, SP-SM poorly graded sand with silt, SP-SC poorly graded sand with clay.

E Cu = D60/D10 Cc =

F If soil contains ≥ 15% sand, add “with sand” to group name.

G If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM.

H If fines are organic, add “with organic fines” to group name.

I If soil contains ≥ 15% gravel, add “with gravel” to group name.

J If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay.

K If soil contains 15 to 29% plus No. 200, add “with sand” or

“with gravel,” whichever is predominant.

L If soil contains ≥ 30% plus No. 200 predominantly sand, add

“sandy” to group name.

M If soil contains ≥ 30% plus No. 200, predominantly gravel, add

“gravelly” to group name.

N PI ≥ 4 and plots on or above “A” line.

O PI < 4 or plots below “A” line.

P PI plots on or above “A” line.

Q PI plots below “A” line.

DxD

)(D

CPT GENERAL NOTES

DESCRIPTION OF MEASUREMENTS DESCRIPTION OF GEOTECHNICAL CORRELATIONS

AND CALIBRATIONS

REPORTED PARAMETERS

CONE PENETRATION SOIL BEHAVIOR TYPE

WATER LEVEL

Effective Friction Angle, '

0.1 1 10

N O

R M

A L

IZ

E D

C O

N E

R E

S

IS

T A

N C

E q t a tm

4 Silt mixtures - clayey silt to silty clay

5 Sand mixtures - silty sand to sandy silt

6 Sands - clean sand to silty sand

1 Sensitive, fine grained

2 Organic soils - clay

3 Clay - silty clay to clay

7 Gravelly sand to dense sand

8 Very stiff sand to clayey sand

9 Very stiff fine grained

Undrained Shear Strength, Su

Low Reliability High Reliability

* improves with seismic Vs measurements

Reliability of CPT-predicted N values as commonly measured by the Standard Penetration Test (SPT) is not provided due to the inherent inaccuracy associated with the SPT test procedure.

Kulhawy, F.H., Mayne, P.W., (1997). "Manual on Estimating Soil Properties for Foundation Design," Electric Power Research Institute, Palo Alto, CA.

Mayne, P.W., (2013). "Geotechnical Site Exploration in the Year 2013," Georgia Institue of Technology, Atlanta, GA.

Robertson, P.K., Cabal, K.L. (2012). "Guide to Cone Penetration Testing for Geotechnical Engineering," Signal Hill, CA.

Schmertmann, J.H., (1970). "Static Cone to Compute Static Settlement over Sand," Journal of the Soil Mechanics and Foundations Division, 96(SM3), 1011-1043.

REFERENCES

atm = atmospheric pressure = 101 kPa = 1.05 tsf

NORMALIZED FRICTION RATIO, FR

Permeability, k

Constrained Modulus, M

Unit Weight

Sensitivity, St

Over Consolidation Ratio, OCR

Small Strain Modulus, G

* and

Elastic Modulus, Es*

RELATIVE RELIABILITY OF CPT CORRELATIONS

Soil Behavior Type Index, Ic Ic = [(3.47 - log(Q t

+ (log(FR) + 1.22) 0.5

Normalized Tip Resistance, Q t

Q t = (q t

V0

V0

The groundwater level at the CPT location is used to normalize the measurements for vertical overburden pressures and as a result influences the normalized soil behavior type classification and correlated soil parameters. The water level may either be "measured" or "estimated:"

Measured - Depth to water directly measured in the field Estimated - Depth to water interpolated by the practitioner using pore pressure measurements in coarse grained soils and known site conditions

While groundwater levels displayed as "measured" more accurately represent site conditions at the time of testing than those "estimated," in either case the groundwater should be further defined prior to construction as groundwater level variations will occur over time.

CPT logs as provided, at a minimum, report the data as required by ASTM D5778 and ASTM D7400 (if applicable).

This minimum data include tip resistance, sleeve resistance, and porewater pressure. Other correlated parameters may also be provided. These other correlated parameters are interpretations of the measured data based upon published and reliable references, but they do not necessarily represent the actual values that would be derived from direct testing to determine the various parameters. The following chart illustrates estimates of reliability associated with correlated parameters based upon the literature referenced below.

Over Consolidation Ratio, OCR

OCR (1) = 0.25(Q

t 1.25

OCR (2) = 0.33(Q

t

Sensitivy, St St = (q t

V0 /N kt ) x (1/fs)

Undrained Shear Strength, Su Su = Q t x '

V0 /N kt

N kt is a geographical factor (shown on Su plot)

To be reported per ASTM D5778:

Where a is the net area ratio, a lab calibration of the cone typically between 0.70 and 0.85

Clay and Silt Sand

Sand

7 8

The estimated stratigraphic profiles included in the CPT logs are based on relationships between corrected tip resistance (q t ), friction resistance (fs), and porewater pressure (U2). The normalized friction ratio (FR) is used to classify the soil behavior type.

Clay and Silt

Clay and Silt Sand

Sand

Sand

Clay and Silt Sand

Clay and Silt

Clay and Silt

Clay and Silt

Effective Friction Angle, ' ' (1) = tan

-1 (0.373[log(q t

V0 ) + 0.29])

' (2) = 17.6 + 11[log(Q t

Hydraulic Conductivity, k For 1.0 < Ic < 3.27 k = 10

(0.952 - 3.04Ic)

For 3.27 < Ic < 4.0 k = 10 (-4.52 - 1.37Ic)

Constrained Modulus, M

M = M (q t

V0

For Ic > 2.2 (fine-grained soils)

M = Q t with maximum of 14

For Ic < 2.2 (coarse-grained soils)

M = 0.0188 x 10

(0.55Ic + 1.68)

Small Strain Modulus, G

G

= Vs

Shear Wave Velocity, Vs Measured in a Seismic CPT and provides direct measure of soil stiffness

Normalized Friction Ratio, FR The ratio as a percentage of fs to q t accounting for overburden pressure

Sleeve Friction, fs Frictional force acting on the sleeve divided by its surface area

Pore Pressure, U1/U2 Pore pressure generated during penetration U1 - sensor on the face of the cone U2 - sensor on the shoulder (more common)

Corrected Tip Resistance, q t

Cone resistance corrected for porewater and net area ratio effects q t = q c + U2(1 - a)

Uncorrected Tip Resistance, q c

Measured force acting on the cone divided by the cone's projected area

Unit Weight UW = (0.27[log(FR)]+0.36[log(q t /atm)]+1.236) x UW water

V0 is taken as the incremental sum of the unit weights

SPT N

N

= (q t /atm) / 10

(1.1268 - 0.2817Ic)

To be reported per ASTM D7400, if collected:

Clay and Silt

Typically, silts and clays have high FR values and generate large excess penetration porewater pressures; sands have lower FRs and do not generate excess penetration porewater pressures.

Negative pore pressure measurements are indicative of fissured fine-grained material. The adjacent graph (Robertson et al.) presents the soil behavior type correlation used for the logs. This normalized SBT chart, generally considered the most reliable, does not use pore pressure to determine SBT due to its lack of repeatability in onshore CPTs.

Elastic Modulus, Es (assumes q/q ultimate

~ 0.3, i.e. FS = 3) Es (1) = 2.6 G where = 0.56 - 0.33logQ t,clean sand

Es (2) = G

Es (3) = 0.015 x 10 (0.55Ic + 1.68)

(q t

V0

Es (4) = 2.5q t

Seismic Design Parameters Based on IBC2018 Code and ASCE 7-16 Standard Terracon Project Name: Butterbean Beach Flagpole Terracon Project No: ES255084

Site Location: Savannah, Chatham County, Georgia Latitude : 31.9481° Longitude : -81.0677°

Site Class: D Design Response Spectrum for the Site Class

Ss = 0.292 S1 = 0.109 Fa = 1.566 Fv = 2.383

SMS = 0.458 SM1 = 0.259

SDS = 0.305 SD1 = 0.172

Period (sec) Sa (g)

0.000 0.122

T0 = 0.113 0.305

0.200 0.305

TS = 0.564 0.305

T = 0.600 0.287

0.700 0.246

0.800 0.215

0.900 0.191

1.000 0.172

1.100 0.156

1.200 0.143

1.300 0.132

1.400 0.123

1.500 0.115

1.600 0.108

1.700 0.101

1.800 0.096

1.900 0.091

2.000 0.086

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20

0.22

0.24

0.26

0.28

0.30

0.32

0.34

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

D es ig n

Sp ec tr a

Ac ce le ra tio n

(g

Period (sec)