B09_Att_26_FOSU_Geotechnical_Report_0002.pdf

Fort Sumter and Fort Moultrie

Replace and Rehabilitate Docks

FOSU 318708

Geotechnical Report

Submitted to:

DHM Design

900 S. Broadway, Suite 300

Denver, CO 80209

Submitted by:

CHILDS EN GIN EERIN G P a g e | 2|

TABLE OF CONTENTS

1.0 INTRODUCTION

2.0 PROJECT BACKGROUND

3.0 GEOTECHNICAL FINDINGS AND SOILS CHARACTERIZATION

4.0 CONCLUSIONS

APPENDIX A – Sub consultant testing and report

Replace and Rehabilitate Docks

Geotechnical Test Report

Submitted by:

Childs Engineering

34 William Way

Bellingham, MA 02019

508-966-9092 www.childseng.com

Submitted to:

DHM Design

900 S. Broadway, Suite 300

Denver, CO 80209

Childs Project No. 2983-22.02

Date of Borings: March 20 through 22, 2023

CHILDS EN GIN EERIN G P a g e | 4|

1.0 INTRODUCTION

The purpose of this investigation was to perform geotechnical testing and an analysis of the seabed at the docks at Fort Sumter and Fort Moultrie to assist in the design of new docks to replace the existing docks that have reached the end of their service life.

The task was to perform two soils borings near the proposed dock locations, obtain soils samples for lab testing analysis, calculate bearing capacities and other physical properties, and to provide a report of the geotechnical results. The project site was located at the outshore end of the Fort Sumter dock located in the Charleston Harbor at Fort Sumter Island in Charleston, South Carolina and at the outshore end of the Fort Moultrie dock located in the Cove at Sullivan’s Island, South Carolina.

As part of this assignment, Childs Engineering provided the project management and boring/sampling oversite for the onsite work and reporting of the geotechnical testing.

Childs Engineering used the sub consultant, Soils Consultants, Inc., based in Charleston, SC, to conduct the boring, soils sampling, and sample testing and analysis. The goal of this project was to determine the geotechnical properties and information required to assist in the design of new docks at both locations that will be used for visitor access as well as ship mooring and berthing.

2.0 PROJECT BACKGROUND

The Fort Sumter fixed pier was constructed in 1991 and provides berthing for the National Park and passenger ferry vessels. The pier also provides pedestrian access to the Fort Sumter National Monument for visitors and National Park Service personnel.

The pier is a fixed concrete, T-shaped pier that extends northwest along the stem from the shoreline and turns north intersecting the outshore portion of the “T” and measures approximately 315 foot long by 130 foot wide, consisting of a concrete deck overlay on precast pre-stressed concrete planks and cast in place pile caps supported by 14 and 16 inch square precast pre-stressed concrete piles.

The structure exhibits distress in the form of significant cracks found on the underdeck of the concrete planks. Recent structural investigations and analyses have determined that pier has an estimated remaining service life of 2 years before localized failures occur.

CHILDS EN GIN EERIN G P a g e | 5|

Locus Map of Fort Sumter

The Fort Moultrie fixed pier and floating dock is of similar construction and was built around 1975. It provides a land-based point of access for Fort Sumter maintenance and service personnel, as well as an area of recreation for local citizens and visitors.

The pier is a fixed concrete, T-shaped pier that extends 200 feet northeast along the stem from the shoreline. The outshore portion of the “T” measures approximately 135 foot long by 20 foot wide, consisting of a concrete deck overlay on precast pre-stressed concrete planks and cast in place pile caps supported by 14- and 16-inch square precast pre-stressed concrete piles. Off the east end of the pier is a gangway that provides access to a 60 foot by 8-foot concrete floating dock.

Although the structure has not been inspected in over six years, significant deterioration has been noticed on site visits. Due to the advanced age of the structure and the known defects, it is assumed that this structure is also nearing its end of service life.

Fort Sumter Dock

Fort Sumter National

Monument

CHILD S EN G IN EERIN G P a g e | 6|

Locus Map of Fort Moultrie

3.0 GEOTECHNICAL FINDINGS AND SOILS CHARACTERIZATION

The geotechnical testing and analysis was performed on soils samples taken on April 18th and 19th, 2023 at Fort Sumter and May 1st and 2nd, 2023 at Fort Moultrie. The soils were generally determined to have Coastal Plain sediments to depths of 43-48 feet below the mudline at Fort Sumter and 38 feet below the mudline at Fort Moultrie. Below these sediments was a layer of the locally referred “Cooper Marl” Formation to the termination of the borings at depths of 76.5 feet below the mudline. Additional testing, along with information from the boring logs, was used to determine the engineering properties of the soils. Results and analysis showed that the soft upper soils would not be suitable for the design of a new fender system; however, the soils of the underlying Cooper Marl sediments could support deep foundations used to provide the anticipated capacities for both axial and lateral support.

4.0 CONCLUSIONS

The geotechnical analysis shows that the material encountered within the Cooper Marl soils is adequate to resist vertical loadings through skin friction. The geotechnical report also recommends that 2 test piles, that could also become production piles, be

Fort Moultrie Dock

CHILDS EN GIN EERIN G P a g e | 7| used to perform dynamic pile load testing to confirm the pile capacities and to detect any unusual installation condition encountered.

Based on the geotechnical report findings, it is anticipated that standard air or hydraulic impact hammers with 30 to 40 kip-feet rated energies, or diesel impact hammers with rated energies of 45 to 65 kip-feet, should be suitable for driving the piles typically found on similar projects.

Childs Engineering appreciates the opportunity to present our findings and assessment from our recent geotechnical investigation. If you have any questions or comments on this report, please don’t hesitate to contact me.

Thank you, Nicholas Sarata, P.E.

Vice President Childs Engineering.

APPENDIX A

Geotechnical Testing and Report

GEOTECHNICAL REPORT

PROPOSED DOCK IMPROVEMENTS

FORT SUMTER AND FORT MOULTRIE

CHARLESTON, SOUTH CAROLINA

PREPARED FOR

CHILDS ENGINEERING CORPORATION

SCI PROJECT 230012

JUNE 23, 2023

SCDOT DBE and SBE Charleston County SBE City of Charleston WBE

June 23, 2023

Childs Engineering Corporation 34 William Way Bellingham, MA 02019

Attention: Mr. Nic Sarata

SCI Project 230012

Dear Mr. Sarata:

Soil Consultants, Inc. (SCI) submits this report to provide results of the geotechnical services provided for the proposed replacement of the existing docks located at Fort Sumter and Fort Moultrie in Charleston and Sullivans Island, SC. Our services were performed in accordance with SCI Proposal No. 14-22-209 (revised), dated December 22, 2022. This report provides a discussion of the proposed development, exploration procedures used, subsurface conditions encountered, seismic analysis, and recommendations for foundation design. We appreciate the opportunity to be of service to you during the design phase of this project. If we may be of further assistance during design or as construction proceeds, please call.

Analyses by: Reviewed by:

6/23/2023

6/23/2023

Ronald R. Austin, P.E. A. Talbot Henderson, III, P.E.

TABLE OF CONTENTS

Page

Page i SCI Project No. 230012

INTRODUCTION

SCOPE OF PROJECT

SITE DESCRIPTION

FIELD EXPLORATION

LABORATORY TESTING

BORING LOGS

SUBSURFACE CONDITIONS

Stratigraphy

SEISMIC CONSIDERATIONS

Liquefaction Potential

Seismic Design Parameters

FOUNDATION DESIGN AND CONSTRUCTION CONSIDERATIONS

Deep Foundations

LIMITATIONS OF REPORT

FIGURES

Boring Location Plan

ATTACHMENTS

Soil Boring Logs

Key to Boring Log Symbols and Terms

Laboratory Test Results

Allowable Axial Compressive Pile Capacity Chart

Lateral Pile Analyses Graphs

Page 1 SCI Project No. 230012

INTRODUCTION

Soil Consultants, Inc. (SCI) presents this report to document geotechnical findings and recommendations for the proposed replacement of the existing docks located at Fort Sumter and

Fort Moultrie in Charleston and Sullivans Island, SC. Geotechnical services were performed in accordance with SCI Proposal No. 14-22-209 (revised), dated December 22, 2022. Our services were authorized via the Agreement for Geotechnical Services, which was signed on January 24, 2023.

SCOPE OF PROJECT

Based on the provided project information, we understand the proposed improvements include replacement of the existing docks and fender systems at the existing Fort Sumter and Fort

Moultrie facilities. We have been provided preliminary design concepts for the proposed dock replacements. Based on project information provided, we understand that the fixed piers at both forts are planned to be supported on 14-inch square and 16-inch square pre-cast/pre-stressed

(PCPS) concrete piles. In addition, we understand that the floating dock at Fort Moultrie will utilize

16-inch diameter steel pipe piles for the guide piles. We have also been informed that the fenders at both dock sites will be supported on steel pipe piles, and for the purposes of this report, we assume that the fender piles will be 16-inch diameter pipe piles. Further, we have been provided aerial photography showing suggested locations for the requested borings.

No design structural loading information for the proposed dock replacements has been provided at the time of this report.

SITE DESCRIPTION

The existing Fort Sumter dock is located in the Charleston Harbor and extends out from the northwestern portion of Fort Sumter. The existing Fort Moultrie dock is located on a tributary creek of the Intracoastal Waterway and extends out from Fort Moultrie, which is located on the north side of Sullivan’s Island. We have been provided Layout Plan drawings showing the layout of the existing docks and pier heads at the sites, and the proposed layouts for the new docks and facilities. The drawings also show contour lines depicting the bottom elevations of the harbor and creek in these areas.

Based on the contour lines shown on the provided drawings, the elevations of the harbor bottom in the vicinity of the existing Fort Sumter pier head range from approximately -12 feet to -20 feet, and the elevations of the creek bottom in the vicinity of the existing Fort Moultrie pier head range from approximately -3 feet to -7 feet. For the purposes of this report, we assume that the elevations are referenced to mean low water (MLW), as referenced on Sheets M101 and M201.

We used the elevations indicated on the provided drawings to prepare our report, and any elevations stated in our report are based on the elevations shown on the drawings provided.

FIELD EXPLORATION

On April 18 and 19, 2023, we performed two soil borings, designated CEC-1 and CEC-2, at the

Fort Sumter dock, and on May 1 and 2, 2023, we performed two soil borings, designated CEC-3 and CEC-4, at the Fort Moultrie dock. The borings were performed using mud-rotary drilling procedures at the locations shown on the aerial photography provided. Approximate boring locations are shown on Figures 1 and 2, Boring Location Plans, attached. Boring CEC-1 was advanced to a depth of approximately 55 feet below the existing harbor bottom and Boring CEC-2

Page 2 SCI Project No. 230012 was advanced to a depth of approximately 75 feet below the existing harbor bottom. Borings

CEC-3 and CEC-4 were advanced to depths of approximately 70 feet below the existing creek bottom. All of the borings were planned to be advanced to depths of 75 feet; however, some boring depths were reduced due to time/budget constraints. The Fort Sumter dock borings were performed using track-mounted drilling equipment that was secured onto a marine barge platform, and the Fort Moultrie dock borings were performed using our marshy-buggy mounted drilling equipment. During drilling, split-spoon sampling and Standard Penetration Testing (SPT) were performed at selected intervals. Our experienced drilling personnel visually classified the recovered samples and placed them into sealed sample containers for transport to our laboratory.

Soil samples from this exploration will be retained for a period of three months from the date of this report. Unless other arrangements are made, they will be disposed of following this period.

LABORATORY TESTING

We performed soil mechanics laboratory tests on selected samples to aid in soil classification and to determine engineering properties for use in liquefaction analyses. The test name, test method, and number of tests that we performed are presented in Table 1. Test results are included as an attachment.

Table 1 Laboratory Testing Program

Test Name Test Method Number of Tests

Natural moisture content ASTM D2216 30

Liquid and plastic limits ASTM D4318 12

Percent finer than 75-m sieve ASTM D1140 30

BORING LOGS

SCI’s geotechnical engineer developed the final log for each boring using SPT data and visual descriptions recorded during the field exploration, visual classification of the recovered materials after return to the SCI laboratory, and results of laboratory testing. The boring logs attached to this report represent SCI’s interpretation of stratigraphy and groundwater conditions at the explored locations based on visual classification of recovered samples. Transition boundaries between soil types noted on the boring logs are approximate.

SUBSURFACE CONDITIONS

Generalized stratigraphy and groundwater are discussed in the following paragraphs. The subsurface and groundwater conditions are based on conditions encountered at the boring locations and to the depths explored. All references to depth are approximate and are made with respect to the existing harbor/creek bottom at the time the borings were performed.

Stratigraphy

Subsurface conditions encountered in the borings were generally similar.

The borings generally encountered interbedded layers of coarse-grained and fine-grained soils typical of Coastal Plain sediments to depths of 43 feet and 48 feet at Fort Sumter and to depths of 38 feet at Fort Moultrie. The coarse-grained soils consisted of very loose to medium dense, Page 3 SCI Project No. 230012 fine-grained sands with varying amounts of silt and clay. SPT resistance (N) values obtained in the sands ranged from 0 to 28 blows per foot (bpf). The fine-grained soils consisted of very soft to firm clays with N values ranging from 0 to 5 bpf. Underlying the interbedded sand and clay layers, the borings encountered very soft to hard and medium dense sediments of the Cooper

“Marl” Formation with N values ranging from 0 to 33 bpf to termination of the borings at depths of

56½ feet, 71½ feet, and 76½ feet. The Cooper Marl sediments are typically calcareous silty soils that contain varying sand, shell, and phosphate nodule content. They typically vary in the Unified

Soil Classification System from silty or clayey sands (SM or SC) to silts or clays of low to high plasticity (ML/MH or CL/CH).

SEISMIC CONSIDERATIONS

Seismic analysis is required in accordance with the International Building Code, 2021 Edition

(IBC). The IBC references the American Society of Civil Engineers (ASCE) 7-16, Minimum Design

Loads for Buildings and Other Structures. Therefore, the procedures described in ASCE 7-16 were used.

Seismic considerations include liquefaction of relatively clean, submerged loose sands due to shaking as well as subsequent ground movements associated with shearing or consolidation of the liquefied soils.

Liquefaction Potential

To evaluate the potential for liquefaction, initial determination of site class is needed. The IBC requires soil information to a depth of 100 feet be used in site classification. However, ASCE 7-

10, Section 20.1 states “Where site-specific data are not available to a depth of 100 ft, appropriate soil properties are permitted to be estimated by the registered design professional preparing the soil investigation report based on known geologic conditions.” SCI used weighted average N values, with extrapolated soil conditions between the boring termination depths and 100 feet as permitted by ASCE 7-16, to determine the site class. Based on the weighted average N values, the site may be initially considered as Site Class E.

Liquefaction analyses were performed using Seed's simplified procedure, as updated and documented by Youd et al (2001), considering the material types and depths to groundwater encountered in the borings and a design earthquake with a magnitude of 7.3 having a 2% probability of exceedance in a 50-year period as required by IBC 2021. The Maximum Considered

Earthquake Geometric Mean (MCEG) peak ground accelerations adjusted for site class effects

(PGAM) used in liquefaction analyses were 0.871g and 0.763g for Fort Sumter and Fort Moultrie, respectively. We used the USGS Earthquake Hazards program to determine PGAM based on Site

Class E for both sites.

Results of the liquefaction analysis indicate that potentially liquefiable layers of sands exist at various depths and extend to depths of approximately 48 feet and 28 feet below the harbor/creek bottom at Fort Sumter and Fort Moultrie, respectively. Calculations indicate that approximately

4 to 5 inches of liquefaction-induced total settlement could occur at those locations as a result of the design seismic event. We note that the risks of liquefaction should be fully mitigated for structures supported on deep foundations in accordance with the deep foundation recommendations provided later in this report.

Page 4 SCI Project No. 230012

Seismic Design Parameters

Because of the potential for liquefaction, the site is characterized as Site Class F. However, ASCE

7-16 allows the design spectral response accelerations for a site to be determined without regard to liquefaction provided structures have a fundamental period of less than or equal to 0.5 second and the risks of liquefaction are considered in structure design. If the proposed structures meet the requirements of the exception, as determined by the structural engineer, and liquefaction risks are considered in the design, Site Class E could be used for this project.

Section 11.4.8 of ASCE 7-16 states that a (site specific) ground motion hazard analysis shall be performed for structures on Site Class E sites with SS greater than 1.0 g or S1 greater than 0.2 g.

SS for the Fort Sumter site is 1.227g, and S1 is 0.363g, and SS for the Fort Moultrie site is 1.098g, and S1 is 0.325g. However, for the purposes of this report, we assume that Exceptions 1 and 3 in

Section 11.4.8 of ASCE 7-16 would apply for this project, so a site-specific ground motion hazard analysis would not be required. The applicability of Exceptions 1 and 3 should be verified by the project structural engineer. If Exceptions 1 and 3 are not applicable, please contact us because a site-specific ground motion hazard analysis may be required. Seismic design parameters based on Site Class E are presented in Tables 2 and 3 for the sites at Fort Sumter and Fort Moultrie, respectively.

Table 2 Seismic Design Parameters – Fort Sumter

Seismic Design Parameter Design Value

Short-period site coefficient (at 0.2 s period) Fa 1.20

Long-period site coefficient (at 1.0 s period) Fv 2.548

Mapped MCER, 5 percent damped, spectral response acceleration parameter at short periods

SS 1.227

Mapped MCER, 5 percent damped, spectral response acceleration parameter at a period of 1 s

S1 0.363

Design, 5% damped, spectral response acceleration parameter at short periods

SDS 0.982

Design, 5 % damped, spectral response acceleration parameter at a period of 1 s

SD1 0.617

Based on Site Class E.

Assumes exception for fundamental period applies otherwise Site Class F will apply requiring a site response analysis.

Assumes Exceptions 1 and 3 in Section 11.4.8 of ASCE 7-16 applies.

Page 5 SCI Project No. 230012

Table 3 Seismic Design Parameters – Fort Moultrie

Seismic Design Parameter Design Value

Short-period site coefficient (at 0.2 s period) Fa 1.20

Long-period site coefficient (at 1.0 s period) Fv 2.70

Mapped MCER, 5 percent damped, spectral response acceleration parameter at short periods

SS 1.098

Mapped MCER, 5 percent damped, spectral response acceleration parameter at a period of 1 s

S1 0.325

Design, 5% damped, spectral response acceleration parameter at short periods

SDS 0.878

Design, 5 % damped, spectral response acceleration parameter at a period of 1 s

SD1 0.585

Based on Site Class E.

Assumes exception for fundamental period applies otherwise Site Class F will apply requiring a site response analysis.

Assumes Exceptions 1 and 3 in Section 11.4.8 of ASCE 7-16 applies.

FOUNDATION DESIGN AND CONSTRUCTION CONSIDERATIONS

Because soft soils were encountered in the borings and because we understand that the proposed improvements will be supported on deep foundations, we have provided recommendations for the installation of driven pile deep foundations in this report. If piles are installed as recommended in this report, liquefaction-induced settlement of the proposed improvements should be fully mitigated.

A study of the subsurface conditions encountered in the borings shows that soils on which deep foundations could depend for support were not consistently found above the Cooper Marl sediments. The Cooper Marl sediments were encountered at depths of approximately 43 feet and

48 feet below the existing harbor bottom at Fort Sumter and at depths of approximately 38 feet below the existing creek bottom at Fort Moultrie. Therefore, pile bearing will be assumed to begin at the depth of the top of the Cooper Marl and develop primarily through skin friction with penetration into the underlying Cooper Marl sediments. For the purposes of this report, an elevation of -64 feet (MLW) was assigned to the top of the Cooper Marl at the Fort Sumter site, and an elevation of -38 feet (MLW) was assigned to the top of the Cooper Marl at the Fort Moultrie site.

Deep Foundations

As stated in the Scope of Project section, we understand that the proposed improvements will likely be supported on 14-inch and 16-inch square PCPS concrete piles and 16-inch diameter steel pipe piles. Therefore, recommendations for these piles are provided.

Axial Pile Capacity. Because the pile design loads are not known at this time, we performed analyses to determine the pile embedment depths necessary for the piles to develop axial compressive capacities ranging from 75 kips to 200 kips, and the recommended corresponding pile tip penetrations are provided in graphical form on the Allowable Axial Compressive Pile

Page 6 SCI Project No. 230012

Capacity chart included as an attachment. Based on our experience with pile foundations embedded in the Cooper Marl sediments, the allowable axial tensile capacities of these piles are approximately equal to ⅔ of the axial compressive capacities. The allowable capacities are based on a factor of safety of 2.5 and include reduction for down-drag loading resulting from potential liquefaction settlement.

Test Piles. We recommend performing dynamic pile load testing on at least two test piles at each dock site before production pile installation. The load test program should include at least one test pile for each type/size of pile selected for the project. For concrete piles, dynamic pile load testing should be performed during initial installation of piles using the Pile Driving Analyzer™ (PDA)

(ASTM D4945) to evaluate pile stresses during driving. All test piles (concrete or steel) should be tested during re-strike driving approximately seven days after installation to determine the ultimate axial compression pile capacities and to confirm production pile lengths. This length of time should be allowed between initial installation and re-strike driving to permit the soils to reconsolidate and allow for the dissipation of any excess pore pressures generated during pile installation. The test piles should be widely spaced across the proposed structure footprint to verify capacities in different areas.

In addition to verifying pile capacity, the recommended test piles will determine if any unusual installation conditions would be encountered for the production piles. Test piles will be working piles and should be accurately located per construction drawings. Test pile lengths should allow for a minimum of 6 feet of pile “stickup” above the harbor water surface at high tide after installation to allow for load test equipment attachment. Installation methods for all test piles should be the same as those used during construction.

Since these inspection and testing services are within the scope of services we routinely provide for our clients, we urge that SCI be retained to assist you in performing this testing. We urge that

SCI be retained to select the piles to be load tested, monitor the installation of test piles, perform dynamic load testing, evaluate the test results, confirm the final pile lengths, and monitor the installation of all production piles. Final pile installation criteria for the production piles can be determined based on the contractor’s system and the results of the load testing.

Pile Installation. General comments concerning the installation of driven piles are as follows:

1. Pile penetration depths are referenced to the top of the Cooper Marl. The depths to the Cooper

Marl were measured from the existing harbor bottom at the time that the borings were drilled.

Required pile lengths should include the penetration depth into the Cooper Marl plus the pile length above the top of Cooper Marl elevation to the specified pile top elevations.

2. If adjacent or nearby structures are considered to be vibration-sensitive, we recommend that ground vibrations from driven pile installation be monitored using seismographs to ensure that excessive vibrations are not transmitted to these nearby structures. In addition, we recommend that pre-construction and post-construction surveys be performed on all vibration-sensitive structures in the project vicinity to identify and document pre-construction and post-construction conditions. As part of this process, crack gauges should be installed where deemed appropriate to monitor movements of nearby structures during the construction process.

Page 7 SCI Project No. 230012

3. Spacing between individual piles, measured center-to-center, should be no closer than three times the width or largest diameter of the individual piles.

4. Based on our experience with similar projects, air or hydraulic impact hammers with rated energies of approximately 30 to 45 kip-feet and diesel impact hammers with rated energies of approximately 45 to 65 kip-feet should have sufficient energy to install the piles for this project.

However, greater hammer energy may be required to mobilize sufficient pile capacity for pile testing with the PDA, depending on the required capacity. We believe air or hydraulic impact hammers with rated energies of approximately 40 to 55 kip-feet and diesel impact hammers with rated energies of approximately 60 to 75 kip-feet will be required for pile testing with the

PDA if higher capacities are elected. Upon request, we can provide assistance in evaluating the selected hammer and determining the pile driving criteria.

5. If desired, individual driven pile locations could be pre-augered to a maximum depth of 25 feet below the existing harbor/creek bottom. The auger diameter should not exceed the minimum tip dimension of the piles being driven.

6. All piles, including test piles, should be installed with efficiently operating equipment under experienced supervision. In addition, complete driving and vibration records should be maintained. Since these testing services are within the scope of services we routinely provide for our clients, we urge that SCI be retained to assist you during the pile installation phase.

Lateral Pile Analysis. Lateral load capacity analysis was performed using LPILE® software, which employs p-y analysis to determine the deflections at the ground surface of a single pile under specific loading conditions. All lateral loads are assumed to be applied to the butt of the pile under free-head and fixed-head loading conditions. For the purposes of this report, we assumed that the elevation of the butts of the piles for the proposed dock replacements would be at 8 feet (MLW). We note that loads applied at higher elevations will likely increase calculated deflections and bending moments.

The soil profile data used in LPILE® was modeled after the most critical subsurface conditions encountered in the borings. Input parameters for the encountered soils were estimated based on visual inspection of the soil samples in the laboratory, standard penetration test "N" values correlated with accepted geotechnical references, and our knowledge of the soils in the area. The analyses were performed assuming axial loads of 150 kips. In addition, a wall thickness of ⅜ inch was used for the steel pipe pile analyses.

Design lateral loads were not available at the time of our analysis. Therefore, for the purposes of this report, we performed lateral pile load-deflection analyses to determine the lateral loads that produce lateral deflections of 1 inch and 2 inches for the piles. Since the existing conditions differ, separate analyses were performed for the dock sites. The pile displacements, internal shear forces, and bending moments corresponding to the applied loadings are plotted versus pile depth on the graphs included as attachments. No factor of safety has been applied to the presented data. We recommend that the project structural engineer evaluate the calculated pile bending moments and shear forces to verify that these forces do not exceed allowable values. The results of the analyses for the piles at Fort Sumter and Fort Moultrie are presented in Tables 4 and 5, respectively.

Page 8 SCI Project No. 230012

Table 4 Lateral Load, Maximum Shear, and Maximum Bending Moment for Piles at Fort Sumter

Pile Type

Lateral Capacity

(kips)

Maximum Bending Moment

(kip-feet)

14-inch PCPS Concrete Pile

(Fixed Head, 1-inch Deflection) 1.2 28.3

14-inch PCPS Concrete Pile

(Fixed Head, 2-inch Deflection) 1.9 50.2

14-inch PCPS Concrete Pile

(Free Head, 1-inch Deflection) 0.1 12.7

14-inch PCPS Concrete Pile

(Free Head, 2-inch Deflection) 0.1 23.2

16-inch PCPS Concrete Pile

(Fixed Head, 1-inch Deflection) 1.9 44.8

16-inch PCPS Concrete Pile

(Fixed Head, 2-inch Deflection) 3.1 78.0

16-inch PCPS Concrete Pile

(Free Head, 1-inch Deflection) 0.3 19.6

16-inch PCPS Concrete Pile

(Free Head, 2-inch Deflection) 0.5 35.0

16-inch Steel Pipe Pile

(Free Head, 1-inch Deflection) 0.2 15.0

16-inch Steel Pipe Pile

(Free Head, 2-inch Deflection) 0.2 26.9

Page 9 SCI Project No. 230012

Table 5 Lateral Load, Maximum Shear, and Maximum Bending Moment for Piles at Fort Moultrie

Pile Type

Lateral Capacity

(kips)

Maximum Bending Moment

(kip-feet)

14-inch PCPS Concrete Pile

(Fixed Head, 1-inch Deflection) 2.4 42.3

14-inch PCPS Concrete Pile

(Fixed Head, 2-inch Deflection) 3.9 73.6

14-inch PCPS Concrete Pile

(Free Head, 1-inch Deflection) 0.5 18.6

14-inch PCPS Concrete Pile

(Free Head, 2-inch Deflection) 0.8 32.0

16-inch PCPS Concrete Pile

(Fixed Head, 1-inch Deflection) 3.7 65.3

16-inch PCPS Concrete Pile

(Fixed Head, 2-inch Deflection) 5.9 114.2

16-inch PCPS Concrete Pile

(Free Head, 1-inch Deflection) 1.0 26.8

16-inch PCPS Concrete Pile

(Free Head, 2-inch Deflection) 1.5 46.0

16-inch Steel Pipe Pile

(Free Head, 1-inch Deflection) 0.7 21.3

16-inch Steel Pipe Pile

(Free Head, 2-inch Deflection) 1.0 36.2

As discussed, the LPILE® lateral analysis is performed assuming the use of a single pile under specific loading conditions. When piles are in a closely-spaced group, the shear-failure planes resulting from the movement of each pile will overlap, and the lateral resistance for piles in a group may be less than that of a single pile. Modification or reduction factors are typically employed to account for this reduction in lateral resistance. The group pile response is different for piles in a side-by-side arrangement and for piles in an in-line arrangement in the direction of loading.

For the side-by-side arrangement, when lateral loading is applied perpendicular to the side-by-side alignment of the piles, a modification factor of 0.9 should be used for a pile spacing of three pile widths, measured center to center. If the center-to-center pile spacing is four pile widths or greater, no reduction/modification factor is necessary.

For piles in an in-line arrangement with loading in the direction of the pile alignment, the pile response is different for the leading piles and trailing piles in the arrangement. Table 6 shows recommended pile modification factors for leading piles and trailing piles in an in-line arrangement.

Page 10 SCI Project No. 230012

Table 6 Modification Factors for Piles in an In-Line Group Arrangement

Pile Arrangement Pile Spacing (Pile Widths)

3 4 5 6 7

Leading Piles 0.9 1.0 1.0 1.0 1.0

Trailing Piles 0.7 0.8 0.9 0.95 1.0

Input Parameters for Lateral Pile Analysis

Soil parameters used in our lateral pile analyses are presented in Table 7. Soil parameters were estimated based on visual inspection of the soil samples in the laboratory, standard penetration test "N" values correlated with accepted geotechnical references, and our knowledge of the soils in the area.

Table 7 Soil Parameters for Lateral Pile Analysis

Soil Type

Effective Unit Weight

(pounds/foot3) p-y Modulus, k

(pounds/inch3)

Friction Angle, Φ

(degrees)

Cohesion, c

(pounds/foot2)

Soil Strain, e50

Medium Dense Sands, Silty Sands, and

Clayey Sands

(SP-SM, SM,

and SC)

53 60 32 -- --

Very Soft Clays (CH) and Very Loose Clayey Sands (SC)

28 -- -- 50 0.02

Medium to Stiff Clayey Silts

(MH) (Cooper Marl)

58 200 10 1,500 0.007

Page 11 SCI Project No. 230012

LIMITATIONS OF REPORT

This report was prepared as an instrument of service exclusively for Childs Engineering

Corporation and the project design team in preparation of the foundation design, construction drawings, and construction specifications for the proposed replacements of the existing docks located at Fort Sumter and Fort Moultrie in Charleston and Sullivan’s Island, South Carolina.

Recommendations and comments given in this report are based on the results of the soil borings, combined with interpolation of the subsurface conditions between borings, and the provided and assumed design data. If any changes occur in the design concept or if conditions are encountered during construction that appear to be different from those represented, the conclusions and recommendations contained in this report shall not be considered valid until the changes are reviewed by SCI and our findings and conclusions are verified in writing.

SCI should be given the opportunity to review the design and construction documents. The purpose of this review is to verify that our recommendations are properly incorporated into the project plans and specifications. Review of design and construction documents is not within the scope of authorized services outlined in our proposal; therefore, additional fees would apply.

SCI’s report has been prepared in accordance with generally accepted geotechnical engineering practice with a degree of care and skill ordinarily exercised by reputable geotechnical engineers practicing in this area and the area of the site. Verification of subsurface conditions for the purpose of determining the difficulty of excavation, dewatering, and other construction issues is the responsibility of others specializing in those areas.

SCI Project No. 230012

FIGURES

Reference: Base map provided by Client. Legend:

Note: Boring locations are approximate. Test Boring Location

Scale Not to scale 230012

Date 1

BORING LOCATION PLAN

Proposed Dock Replacement

Fort Sumter

Charleston, SC

Project No.

6/22/2023 Figure

Reference: Base map provided by Client. Legend:

Note: Boring locations are approximate. Test Boring Location

Scale Not to scale 230012

Date 2

BORING LOCATION PLAN

Proposed Dock Replacement

Fort Moultrie

Sullivan's Island, SC

Project No.

6/22/2023 Figure

SCI Project No. 230012

ATTACHMENTS

2-3-5

2/18"

2/18"

WOH/18"

WOH/18"

WOH/18"

3.0

8.0

13.0

18.0

23.0

POORLY GRADED SAND WITH CLAY (SP-SC): medium dense, dark brown, fine, wet, with shells

SANDY LEAN CLAY (CL): very soft, gray, moist

CLAYEY SAND (SC): very loose, gray, fine, moist

SILTY CLAYEY SAND (SC-SM): very loose, gray, fine, wet

CLAYEY SAND (SC): very loose, gray, fine, moist

SANDY LEAN CLAY (CL): very soft to soft, gray, moist

Proposed Dock Replacement

11 feet of water at time of boring. Used 55 feet of temporary casing.

The Soil Consultants, Inc. Key to Boring Log Symbols and Terms contains explanations about symbols and terms used on the boring log.

Fort Sumter (See Boring Plan) Middleton

Remarks:

-13.5 ft Mud Rotary (4-in. diameter)

Location:

Datum:

Elevation:

LOG OF BORING CEC-1

Date Drilled:

Driller:

Project:

MLW

Total Depth:

Drilling Method:

4/18/2023

Water Level:

56.5 ft

SCI Project:

Drill Rig:

230012

CME 850 (Track)

-0

P R

IM

A

R Y

L

O G

S .G

P J/

-0

T E

M P

LA

T

E .G

D T

6/

/2

E le va tio n (f t)

-15

-20

-25

-30

-35

-40

N um be rSample

T yp e

D ep th

Actual Blows (6-in.

interval) 20 40 60 80

(Clays to N60 and Sands to (N1)60)

Corrected N ValueMaterial GraphicMaterial Description

D ep th (f t)

3-1-2

7-10-10

4-4-7

7-8-8

2-4-6

4-5-6

33.0

38.0

48.0

53.0

56.5

SANDY LEAN CLAY (CL): very soft to soft, gray, moist (continued)

CLAYEY SAND (SC): medium dense, gray, fine, wet, with shells

POORLY GRADED SAND WITH SILT (SP-SM): medium dense, gray, fine, wet, with shells

CALCAREOUS CLAYEY SAND (SC) (LOCALLY CALLED MARL): medium dense, olive, fine, moist

CALCAREOUS ELASTIC SILT WITH SAND (MH) (LOCALLY CALLED

MARL): stiff, olive, moist

Boring terminated at 56.5 feet below referenced grade.

Proposed Dock Replacement

11 feet of water at time of boring. Used 55 feet of temporary casing.

The Soil Consultants, Inc. Key to Boring Log Symbols and Terms contains explanations about symbols and terms used on the boring log.

Fort Sumter (See Boring Plan) Middleton

Remarks:

-13.5 ft Mud Rotary (4-in. diameter)

Location:

Datum:

Elevation:

LOG OF BORING CEC-1

Date Drilled:

Driller:

Project:

MLW

Total Depth:

Drilling Method:

4/18/2023

Water Level:

56.5 ft

SCI Project:

Drill Rig:

230012

CME 850 (Track)

-0

P R

IM

A

R Y

L

O G

S .G

P J/

-0

T E

M P

LA

T

E .G

D T

6/

/2

E le va tio n (f t)

-45

-50

-55

-60

-65

-70

N um be rSample

T yp e

D ep th

Actual Blows (6-in.

interval) 20 40 60 80

(Clays to N60 and Sands to (N1)60)

Corrected N ValueMaterial GraphicMaterial Description

D ep th (f t)

7-8-5

WOH/18"

1-5-3

3-3-4

1-1-3

1-2-3

3.0

18.0

28.0

POORLY GRADED SAND (SP): medium dense, gray, fine, wet, with shells

SILTY SAND (SM): very loose to medium dense, gray, fine, wet, with shells

CLAYEY SAND (SC): loose, gray, fine, moist

FAT CLAY WITH SAND (CH): very soft to firm, gray, moist

Proposed Dock Replacement

18 feet of water at time of boring. Used 55 feet of temporary casing.

The Soil Consultants, Inc. Key to Boring Log Symbols and Terms contains explanations about symbols and terms used on the boring log.

Fort Sumter (See Boring Plan) Middleton

Remarks:

-16.0 ft Mud Rotary (4-in. diameter)

Location:

Datum:

Elevation:

LOG OF BORING CEC-2

Date Drilled:

Driller:

Project:

MLW

Total Depth:

Drilling Method:

4/19/2023

Water Level:

76.5 ft

SCI Project:

Drill Rig:

230012

CME 850 (Track)

-0

P R

IM

A

R Y

L

O G

S .G

P J/

-0

T E

M P

LA

T

E .G

D T

6/

/2

E le va tio n (f t)

-20

-25

-30

-35

-40

-45

N um be rSample

T yp e

D ep th

Actual Blows (6-in.

interval) 20 40 60 80

(Clays to N60 and Sands to (N1)60)

Corrected N ValueMaterial GraphicMaterial Description

D ep th (f t)

2-2-2

WOH/18"

1-3-10

4-5-5

1-13-13

2-4-4

38.0

43.0

48.0

FAT CLAY WITH SAND (CH): very soft to firm, gray, moist (continued)

SILTY SAND (SM): medium dense, gray, fine, wet

CALCAREOUS FAT CLAY WITH SAND (CH) (LOCALLY CALLED MARL):

stiff, olive, moist

CALCAREOUS ELASTIC SILT WITH SAND (MH) (LOCALLY CALLED

MARL): very soft to hard, olive, moist

Proposed Dock Replacement

18 feet of water at time of boring. Used 55 feet of temporary casing.

The Soil Consultants, Inc. Key to Boring Log Symbols and Terms contains explanations about symbols and terms used on the boring log.

Fort Sumter (See Boring Plan) Middleton

Remarks:

-16.0 ft Mud Rotary (4-in. diameter)

Location:

Datum:

Elevation:

LOG OF BORING CEC-2

Date Drilled:

Driller:

Project:

MLW

Total Depth:

Drilling Method:

4/19/2023

Water Level:

76.5 ft

SCI Project:

Drill Rig:

230012

CME 850 (Track)

-0

P R

IM

A

R Y

L

O G

S .G

P J/

-0

T E

M P

LA

T

E .G

D T

6/

/2

E le va tio n (f t)

-50

-55

-60

-65

-70

-75

N um be rSample

T yp e

D ep th

Actual Blows (6-in.

interval) 20 40 60 80

(Clays to N60 and Sands to (N1)60)

Corrected N ValueMaterial GraphicMaterial Description

D ep th (f t)

8-10-7

1-3-6

WOH/18"

3-7-7

76.5

CALCAREOUS ELASTIC SILT WITH SAND (MH) (LOCALLY CALLED

MARL): very soft to hard, olive, moist (continued)

Boring terminated at 76.5 feet below referenced grade.

Proposed Dock Replacement

18 feet of water at time of boring. Used 55 feet of temporary casing.

The Soil Consultants, Inc. Key to Boring Log Symbols and Terms contains explanations about symbols and terms used on the boring log.

Fort Sumter (See Boring Plan) Middleton

Remarks:

-16.0 ft Mud Rotary (4-in. diameter)

Location:

Datum:

Elevation:

LOG OF BORING CEC-2

Date Drilled:

Driller:

Project:

MLW

Total Depth:

Drilling Method:

4/19/2023

Water Level:

76.5 ft

SCI Project:

Drill Rig:

230012

CME 850 (Track)

-0

P R

IM

A

R Y

L

O G

S .G

P J/

-0

T E

M P

LA

T

E .G

D T

6/

/2

E le va tio n (f t)

-80

-85

-90

N um be rSample

T yp e

D ep th

Actual Blows (6-in.

interval) 20 40 60 80

(Clays to N60 and Sands to (N1)60)

Corrected N ValueMaterial GraphicMaterial Description

D ep th (f t)

1/18"

1/18"

1/18"

1/18"

1-2-1

6-7-6

13.0

23.0

28.0

FAT CLAY WITH SAND (CH): very soft, gray, moist

CLAYEY SAND (SC): very loose to loose, gray, fine, moist, with shells

SILTY SAND (SM): medium dense, gray, fine, wet, with shells

CLAYEY SAND (SC): loose, dark olive brown, fine, wet

Proposed Dock Replacement

3 feet of water at time of boring. Used 41 feet of temporary casing.

The Soil Consultants, Inc. Key to Boring Log Symbols and Terms contains explanations about symbols and terms used on the boring log.

Fort Moultrie (See Boring Plan) Benbow

Remarks:

-4.0 ft Mud Rotary (4-in. diameter)

Location:

Datum:

Elevation:

LOG OF BORING CEC-3

Date Drilled:

Driller:

Project:

MLW

Total Depth:

Drilling Method:

5/1/2023

Water Level:

71.5 ft

SCI Project:

Drill Rig:

230012

CME 550 (Marsh Buggy)

-0

P R

IM

A

R Y

L

O G

S .G

P J/

-0

T E

M P

LA

T

E .G

D T

6/

/2

E le va tio n (f t)

-5

-10

-15

-20

-25

-30

N um be rSample

T yp e

D ep th

Actual Blows (6-in.

interval) 20 40 60 80

(Clays to N60 and Sands to (N1)60)

Corrected N ValueMaterial GraphicMaterial Description

D ep th (f t)

1-2-1

1-3-4

2-4-5

1-2-4

1-3-3

1-1-3

33.0

CLAYEY SAND (SC): loose, dark olive brown, fine, wet (continued)

CALCAREOUS ELASTIC SILT WITH SAND (MH) (LOCALLY CALLED

MARL): firm to very stiff, olive, moist

Proposed Dock Replacement

3 feet of water at time of boring. Used 41 feet of temporary casing.

The Soil Consultants, Inc. Key to Boring Log Symbols and Terms contains explanations about symbols and terms used on the boring log.

Fort Moultrie (See Boring Plan) Benbow

Remarks:

-4.0 ft Mud Rotary (4-in. diameter)

Location:

Datum:

Elevation:

LOG OF BORING CEC-3

Date Drilled:

Driller:

Project:

MLW

Total Depth:

Drilling Method:

5/1/2023

Water Level:

71.5 ft

SCI Project:

Drill Rig:

230012

CME 550 (Marsh Buggy)

-0

P R

IM

A

R Y

L

O G

S .G

P J/

-0

T E

M P

LA

T

E .G

D T

6/

/2

E le va tio n (f t)

-35

-40

-45

-50

-55

-60

N um be rSample

T yp e

D ep th

Actual Blows (6-in.

interval) 20 40 60 80

(Clays to N60 and Sands to (N1)60)

Corrected N ValueMaterial GraphicMaterial Description

D ep th (f t)

1-2-3

2-4-6

3-7-8

71.5

CALCAREOUS ELASTIC SILT WITH SAND (MH) (LOCALLY CALLED

MARL): firm to very stiff, olive, moist (continued)

Boring terminated at 71.5 feet below referenced grade.

Proposed Dock Replacement

3 feet of water at time of boring. Used 41 feet of temporary casing.

The Soil Consultants, Inc. Key to Boring Log Symbols and Terms contains explanations about symbols and terms used on the boring log.

Fort Moultrie (See Boring Plan) Benbow

Remarks:

-4.0 ft Mud Rotary (4-in. diameter)

Location:

Datum:

Elevation:

LOG OF BORING CEC-3

Date Drilled:

Driller:

Project:

MLW

Total Depth:

Drilling Method:

5/1/2023

Water Level:

71.5 ft

SCI Project:

Drill Rig:

230012

CME 550 (Marsh Buggy)

-0

P R

IM

A

R Y

L

O G

S .G

P J/

-0

T E

M P

LA

T

E .G

D T

6/

/2

E le va tio n (f t)

-65

-70

-75

N um be rSample

T yp e

D ep th

Actual Blows (6-in.

interval) 20 40 60 80

(Clays to N60 and Sands to (N1)60)

Corrected N ValueMaterial GraphicMaterial Description

D ep th (f t)

1/18"

1/18"

1/18"

2-1-1

2-2-5

3-5-5

13.0

23.0

28.0

FAT CLAY WITH SAND (CH): very soft, gray, moist

POORLY GRADED SAND WITH CLAY (SP-SC): very loose to medium dense, gray, fine, wet, with shells

POORLY GRADED SAND WITH SILT (SP-SM): medium dense, gray, fine, wet, with shells

CLAYEY SAND (SC): very loose, dark olive brown, fine, wet

Proposed Dock Replacement

3 feet of water at time of boring. Used 40 feet of temporary casing.

The Soil Consultants, Inc. Key to Boring Log Symbols and Terms contains explanations about symbols and terms used on the boring log.

Fort Moultrie (See Boring Plan) Benbow

Remarks:

-5.5 ft Mud Rotary (4-in. diameter)

Location:

Datum:

Elevation:

LOG OF BORING CEC-4

Date Drilled:

Driller:

Project:

MLW

Total Depth:

Drilling Method:

5/2/2023

Water Level:

71.5 ft

SCI Project:

Drill Rig:

230012

CME 550 (Marsh Buggy)

-0

P R

IM

A

R Y

L

O G

S .G

P J/

-0

T E

M P

LA

T

E .G

D T

6/

/2

E le va tio n (f t)

-10

-15

-20

-25

-30

-35

N um be rSample

T yp e

D ep th

Actual Blows (6-in.

interval) 20 40 60 80

(Clays to N60 and Sands to (N1)60)

Corrected N ValueMaterial GraphicMaterial Description

D ep th (f t)

1/18"

1-4-5

3-5-5

1-3-5

2-4-5

1-1-4

33.0

CLAYEY SAND (SC): very loose, dark olive brown, fine, wet (continued)

CALCAREOUS ELASTIC SILT WITH SAND (MH) (LOCALLY CALLED

MARL): firm to very stiff, olive, moist

Proposed Dock Replacement

3 feet of water at time of boring. Used 40 feet of temporary casing.

The Soil Consultants, Inc. Key to Boring Log Symbols and Terms contains explanations about symbols and terms used on the boring log.

Fort Moultrie (See Boring Plan) Benbow

Remarks:

-5.5 ft Mud Rotary (4-in. diameter)

Location:

Datum:

Elevation:

LOG OF BORING CEC-4

Date Drilled:

Driller:

Project:

MLW

Total Depth:

Drilling Method:

5/2/2023

Water Level:

71.5 ft

SCI Project:

Drill Rig:

230012

CME 550 (Marsh Buggy)

-0

P R

IM

A

R Y

L

O G

S .G

P J/

-0

T E

M P

LA

T

E .G

D T

6/

/2

E le va tio n (f t)

-40

-45

-50

-55

-60

-65

N um be rSample

T yp e

D ep th

Actual Blows (6-in.

interval) 20 40 60 80

(Clays to N60 and Sands to (N1)60)

Corrected N ValueMaterial GraphicMaterial Description

D ep th (f t)

2-4-5

3-6-8

3-4-4

71.5

CALCAREOUS ELASTIC SILT WITH SAND (MH) (LOCALLY CALLED

MARL): firm to very stiff, olive, moist (continued)

Boring terminated at 71.5 feet below referenced grade.

Proposed Dock Replacement

3 feet of water at time of boring. Used 40 feet of temporary casing.

The Soil Consultants, Inc. Key to Boring Log Symbols and Terms contains explanations about symbols and terms used on the boring log.

Fort Moultrie (See Boring Plan) Benbow

Remarks:

-5.5 ft Mud Rotary (4-in. diameter)

Location:

Datum:

Elevation:

LOG OF BORING CEC-4

Date Drilled:

Driller:

Project:

MLW

Total Depth:

Drilling Method:

5/2/2023

Water Level:

71.5 ft

SCI Project:

Drill Rig:

230012

CME 550 (Marsh Buggy)

-0

P R

IM

A

R Y

L

O G

S .G

P J/

-0

T E

M P

LA

T

E .G

D T

6/

/2

E le va tio n (f t)

-70

-75

N um be rSample

T yp e

D ep th

Actual Blows (6-in.

interval) 20 40 60 80

(Clays to N60 and Sands to (N1)60)

Corrected N ValueMaterial GraphicMaterial Description

D ep th (f t)

Concrete Asphalt

Silty Sand (SM)

Standard Penetration Resistance Value (N value) corrected to N60 for clays and to (N1)60 for sands.

Sandy Lean Clay (CL)

Well-Graded Gravel

(GW)

Clayey Sand (SC) Fat Clay (CH) Sandy Fat Clay (CH) Lean Clay (CL)

Silty Clay (CL-ML)

Organic Clay (OH) Organic Silt (OH)

Elastic Silt (MH) Sandy Elastic Silt

(MH)

Organic Clay (OL)

CONSISTENCY OF FINE-GRAINED SOILS

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

Silts and Clays Consistency determined by laboratory strength testing, standard penetration resistance, or field visual-manual procedures.

SPT N Value

The sampler penetrated the full 18-in. test depth under the weight of the drill rod.WOR

WOH

1/18"

Ncorrected

Within a desired sampling interval, the SPT test includes seating the split-barrel sampler to 6-in. depth with blows from a 140-lb hammer. The sampler is advanced through two additional 6-in. deep intervals with blow counts recorded for each interval. The "N" value is the sum of the blows for the final 12 in. of the 18-inch penetration.

STANDARD PENETRATION TEST (SPT)

Thin-walled tube

Split barrel Core No Recovery

SAMPLER SYMBOLS

Organic Silt (OL)

DENSITY OF COARSE-GRAINED SOILS

Peat (PT)

Sandy Silt (ML)

Poorly-Graded Gravel with Sand (GP-GM)

Well-Graded Gravel with Sand (GW-GM)

Consistency Unconfined

Compressive Strength, tsf

50/3"

Auger Sample

LOCAL MATERIAL TYPES AND SYMBOLS

Well-Graded Sand with Silt (SW-SM)

Silt (ML)

(More than 50% retained on the No. 200 Sieve)

< 0.25 Very Soft 0 - 2

3 - 4Soft0.25 to 0.50

1.00 to 2.00

2.00 - 4.00

0.50 to 1.00 Medium (Firm)

Stiff

5 - 8

9 - 15

16 - 30Very Stiff

> 30Hard> 4.00

KEY TO BORING LOG SYMBOLS AND TERMS

USCS MATERIAL TYPES AND SYMBOLS

Clayey Gravel (GC)

Well-Graded Gravel with Clay (GW-GC)

Poorly-Graded Sand with Clay (SP-SC)

Well-Graded Sand

(SW)

Poorly-Graded Gravel

(GP)

RELATIVE DENSITY AND CONSISTENCY

> 50

0 - 4

SPT N ValueRelative Density

Base Wood

Very Loose

Loose

Medium Dense

Dense

Very Dense

Density determined by Standard Penetration Resistance.

Gravels and Sands

Poorly-Graded Gravel with Clay (GP-GC)

11 - 30

Well-Graded Sand with Clay (SW-SC)

Silty Gravel (GM)

Poorly-Graded Sand

(SP)

Poorly-Graded Sand with Silt (SP-SM)

Soil Consultants, Inc.'s geotechnical engineer reviewed recovered samples, field data, and laboratory data to develop each boring log. Each log represents our interpretation of general soil and water conditions at the boring location. Soil classifications presented on the boring log are based on the Unified Soil Classification System (USCS) as outlined in ASTM D2487. The system is used to classify coarse-grained materials (boulders, cobbles, gravel, and sand) and fine-grained materials (silt and clay). Descriptors are added to describe additional constituents based on percentages of these constituents. In the absence of laboratory data required to classify soils in complete accordance with ASTM D2487, visual descriptions of the materials are provided with their interpreted USCS group name.

Subsurface conditions at the explored location(s) may not be indicative…