Solicitation Attachment - Geotechnical Report 14 April 2025.pdf

Geotechnical Exploration Report

JBC Dormitory B464 Retrofit

North Charleston, South Carolina

S&ME Project No. 23130012

PREPARED FOR:

ADC Engineering Inc.

1226 Yeamans Hall Road

Hanahan, South Carolina 29410

PREPARED BY:

S&ME, Inc.

7410 Northside Drive Suite 110

North Charleston, SC 29420

April 14, 2025

S&ME, Inc. | 7410 Northside Drive, Suite 110 | North Charleston, SC 29420 | p 843.884.0005 | www.smeinc.com

April 14, 2025

ADC Engineering Inc.

1226 Yeamans Hall Road

Hanahan, South Carolina 29410

Attention: Ms. Hannah McKool, P.E.

Reference: Updated Geotechnical Exploration Report

JBC Dormitory B464 Retrofit

North Charleston, South Carolina

S&ME Project No. 24130012

Dear Ms. McKool:

We have completed our geotechnical exploration and seismic site-specific response analysis (SSRA) for the referenced project in Charleston, South Carolina. Our services are being provided pursuant to Mr. Mark Dillon’s email request for a seismic site-specific response analysis (SSRA) on January 4th, 2024, and subsequent email from

Mr. Greg Jones on May 23, 2024, providing notice to proceed (NTP). The purpose of our services was to explore the subsurface conditions at the site, evaluate those conditions, and provide recommendations for foundation support. This report presents our understanding of the project, the site and subsurface conditions encountered, and our conclusions and recommendations. Draft SSRA results were presented in two technical memos on

September 13, 2024, and October 11, 2024, as an early deliverable to help advance structural design. Final SSRA results in addition to our geotechnical results were presented in our November 7, 2024, Geotechnical Exploration

Report. The updated report was requested after receiving updated column and wall loads from ADC, and supersedes our November 7, 2024, report.

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

Sincerely, S&ME, Inc.

Samuel W. Folmar, EIT Gregory J. Canivan, PE

Staff Professional III Technical Principal

Updated Geotechnical Exploration Report

North Charleston, South Carolina

S&ME Project No. 24130012

April 14, 2025 2

Project Information

We understand the existing dormitory building 464 at the Joint Base Charleston (JBC) Air Base will be renovated to meet an ASCE 41 Tier 2 study and retrofit design. The existing building is located off Arthur Drive in North

Charleston, South Carolina.

The existing building has a roughly 230 ft by 50 ft footprint. The three-story building is comprised of masonry brick walls and supported on shallow foundations. Our 2024 report was based on retrofit concepts contemplated around the 35% design stage, and this updated report considers the final design based on conversations between

Ms. Hannah McKool of ADC and Mr. Greg Canivan of S&ME in April of 2025. We understand the proposed renovations will include the addition of concrete facing to thicken existing concrete shear walls. We were informed that the current shear wall footings were designed for an allowable pressure of 2,000 psf and understand approximately 2.3 kips/linear foot will be added to the existing wall footings from the additional concrete. Therefore, to support total (i.e., existing, plus additional loads from the current renovation) shear wall loads on the order of 8 to 10 kips/linear foot, we understand the existing footings will be made proportionally larger based on an allowable bearing pressure of 2,500 psf. We were informed that some additional bracing may be incorporated into the exterior walls but understand loads on the existing column footings are not anticipated to increase significantly.

Project information is based on various e-mails from Messrs. Greg Jones, Mark Dillon, Grant Eversmann, and Ms.

Hannah McKool of ADC and to Messrs. David Schoen, Austin Cox, Samuel Folmar, and Greg Canivan of S&ME from January to April of 2025.

The project information and assumptions detailed above should be reviewed and confirmed by the appropriate team members. Modifications to our proposed scope of services may be required if the actual conditions vary from the project information and assumptions described herein.

Methods of Exploration

Field Exploration

Our field exploration included a site reconnaissance by a geotechnical engineer, cone penetration test (CPT) soundings, and hand-auger borings as summarized below:

Three cone penetration test (CPT) soundings to a depth of approximately 40 ft and one to approximately

100 ft below the existing ground surface.

We obtained shear wave velocity measurements to a depth of approximately 90 ft in sounding C-4 at 1-meter intervals to help with our seismic evaluation of the site.

April 14, 2025 3

To further evaluate the near surface soil conditions, we performed a 4-ft-deep hand-auger boring adjacent to each CPT sounding. The soils encountered were visually classified in the field using the Unified

Soil Classification System (ASTM D2488).

Following completion of the borings and soundings, we noted the presence of subsurface water and backfilled the boreholes with the auger cuttings.

The test locations were located in the field using a hand-held GPS device and are shown on the Test Location Plan

(Figure I-1) included in Appendix I. A more detailed description of our field-testing procedures, the CPT sounding and hand-auger boring logs, and shear wave velocity profile (SWVP) (Figure II-1) are provided in Appendix II.

Site and Subsurface Conditions

Site Conditions

The project site is located within the Air Base at JBC off Author Drive. The site is bound by Author Drive to the west, North Davis Drive to the east, Scott Street to the north, and additional dormitories and parking areas to the south. The site has been previously developed and is currently occupied by the existing dormitory, paved sidewalks, asphalt parking areas, and neighboring dormitories. Based on visual observation, the site is relatively level with elevations varying by 1 ft or less.

Subsurface Conditions

Details of the subsurface conditions encountered by the soundings and borings are shown on the logs in

Appendix II. The logs represent our interpretation of the subsurface conditions based upon field data.

Stratification lines on the logs represent approximate boundaries between soil behavior types1; however, the actual transition may be gradual. The general subsurface conditions and their pertinent characteristics are discussed in the following paragraphs.

The exploration within the grassed areas initially encountered approximately 2 to 3 in. of topsoil. Although not encountered in our exploration, there may be existing fill within the building pad. Natural coastal plain soils were encountered beneath the topsoil. The exploration primarily encountered loose to medium dense sands with varying amounts and types of fines (SM to SC to SP) to a depth of approximately 13 ft. Beneath these soils, a relatively thin layer consisting of firm clay and silt (i.e., CL & ML) extended to a depth of approximately 15 ft.

Medium dense silty sand was then found to a depth of approximately 24 ft. Cooper Marl2 was encountered beneath and extended to 92 ft, the maximum exploration depth. Table 1 summarizes the general subsurface conditions encountered at the site.

1 Soil Behavior Type is calculated based on empirical correlations with tip resistance, sleeve friction, and pore pressure. A CPT may define a soil based on its behavior as one type while its grain size and plasticity, the traditional basis for soil classification, may define it as a different type.

2 The Cooper Marl, locally referred to as “marl”, is an incompressible, thick ( 200 ft) stratum which underlies the area and is typically the bearing stratum for deep foundations in the Charleston area.

April 14, 2025 4

Table 1 – Generalized Subsurface Conditions

Approx.

Depth Range

(ft)

Description Comments

0 to ¼ Topsoil n/a

¼ to 13 Loose to M. Dense Sands with varying amounts and types of fines i.e., SP & SM & SC)

Liquefiable sands below the water table

13 to 15 Firm Clay and Silt (i.e., CL & ML) -

15 to 24 M. Dense Silty Sand (i.e., SM) -

24 to 30 Young Marl -

>30 Marl Soundings terminated in the layer

Subsurface Water

Subsurface water was measured upon completion of the soundings at depths of approximately 2 to 4 ft below the existing ground surface. The 4-ft deep hand auger borings did not encounter water. Subsurface water levels at the site will fluctuate during the year due to such things as seasonal and climatic variations and the construction activity in the area.

Conclusions and Recommendations

The exploration indicates the site is adaptable for the proposed construction. Our analysis indicates that the site is underlain by sands with the potential to liquefy3 during the design earthquake events, and the risk of adverse effects to existing shallow foundations and proposed new shallow foundations from liquefaction are low to moderate.

The following presents our geotechnical considerations for the proposed renovation. During review of these recommendations, it should be kept in mind that with any previously developed site, subsurface conditions will vary between our test locations. Unexpected subsurface conditions such as deeper, and/or poorly-compacted fill deposits and buried debris may be encountered. These variable conditions can normally be handled during construction by field engineering.

3 Liquefaction, the loss of a soil’s shear strength due to the increase in porewater pressure resulting from seismic vibrations, is always a potential concern in coastal South Carolina.

April 14, 2025 5

Structural-Related Recommendations

Site-Specific Response Analysis

Based on the measured shear-wave velocity (Vs) data shown in Figure II-1 of Appendix II and our experience in the general area, the average shear-wave velocity to a depth of 100 ft below the existing ground (i.e. VS100) is estimated to be approximately 1,175 ft/s, which corresponds to a non-liquefied Seismic Site Class D based on

Table 20.3-1 of ASCE 7-16. However, as discussed in more detail below, liquefiable soils were encountered at the site which triggers a Seismic Site Class F designation.

As requested, we performed a seismic site-specific response analysis (SSRA) for the site to determine the horizontal response spectral accelerations considering four ASCE 41-17 hazards:

BSE-2N hazard - The ASCE 7-16 MCER based on a 2% probability of exceedance (P/E) in 50 years and factored by risk-targeted coefficients, which results in a 1% risk of structural collapse in 50 years.

BSE-1N hazard - The ASCE 7-16 design event, equal to 2/3 of BSE-2N

BSE-2E hazard – 5% P/E in 50 years

BSE-1E hazard – 20% P/E in 50 years

Per Section 2.4.2.1 of ASCE 41-17, we performed our analyses in general accordance with the procedures outlined in Chapter 21 of ASCE 7-16. We used the computer program DEEPSOIL v7.14 to compute the horizontal response accelerations associated with each hazard. The details regarding our assumptions, methodologies, and results are presented in a calculation package in Appendix III.

The resulting code-limited design response accelerations are presented in Table 2. The general procedure response accelerations are also shown for reference. A high Level of Seismicity (ASCE 41-17 Section 2.5) should be considered for all hazards. The design acceleration response spectra are presented in Appendix III.

Table 2 – Summary of Horizontal Design Acceleration Parameters

ASCE 41-17

Hazard

Site-Specific Procedure General Procedure (Site Class D)

PGAM

(g)

SXS

(g)

SX1

(g)

Level of

Seismicity

PGAM

(g)

SXS

(g)

SX1

(g)

Level of

Seismicity

BSE-2N 1.111 1.491 1.088

High

1.389 1.864 1.434

High

BSE-1N 0.741 0.994 0.725 0.926 1.243 0.956

BSE-2E 0.677 1.284 0.459 0.846 1.250 0.574

BSE-1E 0.203 0.426 0.079 0.251 0.431 0.099

4 DEEPSOIL v7.1 is a one-dimensional site response analysis program that can perform nonlinear and equivalent linear site response analyses with and without pore water pressure control. Hashash, Y.M.A., Musgrove, M.I., Harmon, J.A., Groholski, D.R., Phillips, C.A., and Park, D. (2024). DEEPSOIL 7.1, User Manual. University of Illinois at Urbana-Champaign, Urbana, IL.

April 14, 2025 6

Seismic Considerations and Liquefaction Analysis

We performed liquefaction triggering evaluations based on the four requested hazards outlined in ASCE 41-17 and the simplified procedures presented in Youd et al. (2001) using the measured CPT data. The analyses indicate the saturated loose sands and silty sands between the water table and a depth to approximately 17 ft have the potential to liquefy during the design seismic events. To help evaluate the consequences of liquefaction, we computed the Ishihara-inspired Liquefaction Potential Index (LPIISH)5, which is an empirical tool used to evaluate the potential for liquefaction to cause damage. The index ranges from 0 to 100 and considers the thickness of the non-liquefying crust, the factor of safety against triggering, the thickness of the liquefiable strata, and the depth of the liquefiable strata. An LPIISH of 0 means there is no risk of liquefaction; an LPIISH of 100 means the entire profile is expected to liquefy. The level of risk is generally defined as:

LPIISH < 5 – surface manifestation and liquefaction-induced damage not expected.

5 ≤ LPIISH ≤ 15 – moderate liquefaction with some surface manifestation possible.

LPIISH > 15 – severe liquefaction and foundation damage is likely.

Table 3 summarizes the PGA, LPIish, risk index, and associated vertical settlements of elements (new or existing) supported at grade for the four ASCE 41-17 hazards evaluated:

Table 3: Liquefaction Analysis Summary

Hazard PGAM

(g)

LPIish Risk Predicted Vertical Settlement (in.)

BSE-2N 1.111 3 - 12 Low - Moderate ½ to 1⅓

BSE-1N 0.741 2 - 10 Low - Moderate ½ to 1⅓

BSE-2E 0.677 2 - 10 Low - Moderate ½ to 1⅓

BSE-1E 0.203 < 1 – 1.5 Low ¼ to 1

*Our liquefaction analyses were based on earthquakes with a magnitude of 7.3

The predicted settlements could potentially be entirely differential across the site.

If deep foundations or ground improvement are used under new foundations while the existing foundations have no improvement, the result following the design seismic events would be differential settlements between new and existing foundations. However, if the new foundations are constructed in a similar manner as the existing

(without ground improvement), we anticipate they would have a similar performance following the design seismic events.

5 Maurer, B.W., Green, R.A., and Taylor, O.S. (2015). Moving towards an improved index for assessing liquefaction hazard:

lessons from historical data. Soils and Foundations 55(4):778-787

April 14, 2025 7

Shallow Foundation Recommendations

Conventional shallow foundations for support of the retrofit can be designed for a maximum allowable soil bearing pressure of 2,500 psf, provided the risks associated with liquefaction are accepted. Foundations should bear at least 12 in. below finished grade, and wall and column footings should be a minimum of 18 and 24 in.

wide, respectively.

The results of our analysis of post-construction, static (not seismically-induced) settlement due to the increased shear wall load and maximum bearing pressure of 2,500 psf will be less than 1 in. Differential settlement is typically assumed to be about half of the total settlement. If actual structural loads are greater than those assumed in this report we should be provided with this information so that we can reevaluate settlement.

All foundation excavation bottoms must be evaluated by a representative of the Geotechnical Engineer prior to steel and concrete placement. This evaluation may include probing, hand-auger borings, and dynamic cone penetrometer (DCP) testing, as deemed appropriate. This evaluation will help determine if individual footings are directly underlain by suitable bearing material and is considered part of the geotechnical design. Any loose or soft material should be properly compacted or undercut and replaced with well-compacted controlled fill, crushed aggregate such as No. 57 stone, or crushed concrete meeting SCDOT gradation requirements. If practical, concrete placement should be completed the same day as the footing excavation. Slag is not recommended as backfill due to its potentially expansive nature.

Limitations of Report

This report has been prepared in accordance with generally accepted geotechnical engineering practice for specific application to this project. The conclusions and recommendations contained in this report are based upon applicable standards of our practice in this geographic area at the time this report was prepared. No other representation or warranty, either expressed or implied, is made.

We relied on project information given to us to develop our conclusions and recommendations. If project information described in this report is not accurate, or if it changes during project development, we should be notified of the changes so that we can modify our recommendations based on this additional information if necessary.

Our conclusions and recommendations are based on limited data from a field exploration program. Subsurface conditions can vary widely between explored areas. Some variations may not become evident until construction. If conditions are encountered which appear different than those described in our report, we should be notified. This report should not be construed to represent subsurface conditions for the entire site.

Unless specifically noted otherwise, our field exploration program did not include an assessment of regulatory compliance, environmental conditions or pollutants or presence of any biological materials (mold, fungi, bacteria).

If there is a concern about these items, other studies should be performed. S&ME can provide a proposal and perform these services if requested.

April 14, 2025 8

S&ME should be retained to review the final plans and specifications to confirm that earthwork, foundation, and other recommendations are properly interpreted and implemented. The recommendations in this report are contingent on S&ME’s review of final plans and specifications followed by observation and monitoring of earthwork and foundation construction activities.

April 14, 2025 i

Appendices

April 14, 2025 ii

Appendix I – Figures

Test Location Plan (Figure I-1)

SCALE:

DATE:

PROJECT NUMBER:

FIGURE NO.

I-1

NTS

10-03-2024

23130012

JBC Dormitory B464 Retrofit North Charleston, South Carolina

TEST LOCATION PLAN

NOTE:

Test Locations shown are approximate. This plan is for reference only and should not be used for determining distances or quantities.

LEGEND

CPT / Hand Auger Location

SCPT / Hand Auger Location

C-01

C-03 C-04

C-02

April 14, 2025 iii

Appendix II – Field Exploration Data

CPT Sounding Logs

Hand Auger Boring Logs

Shear Wave Velocity Profile (Figure II-1)

Field Testing Procedures

Sands-Clean Sand to Silty Sand

Sands-Clean Sand to Silty Sand

Sands-Clean Sand to Silty Sand

Sands-Clean Sand to Silty Sand

Sand Mixtures-Silty Sand to Sandy Silt

Sands-Clean Sand to Silty Sand

Sands-Clean Sand to Silty Sand

Electronic Filename: C-01.DAT

Depth (ft)

Tip Resistance qt

(tsf)

80 160 240 320

Cone Size: 1.75 2 ft

SBTFr

MAI = 5

Sleeve Friction fs

(tsf)

1 2 3 4

Pore Pressure u2

(tsf)

0 20 40 60

Friction Ratio Rf

2 4 6 8

40.0 ft Target Depth

Joint Base Charleston B464 Retrofit North Charleston, SC

S&ME Project No: 24130012 Total Depth:

Termination Criteria:

Date:

Estimated Water Depth:

Rig/Operator:

Aug. 21, 2024

Morooka/MW | RH

C P

T R

E P

O R

T

S T

A N

D A

R D

S

B T

F R

2.

G P

J \ S

M

E .G

D T

9/

5/

Depth (ft)

101 100

Equivalent N60

80604020 qt

(tsf) u0

0 2 4 6 u2

(tsf)

Cone Penetration Test

Sounding ID: C-01

Sands-Clean Sand to Silty Sand

Sand Mixtures-Silty Sand to Sandy Silt

Sand Mixtures-Silty Sand to Sandy Silt

Sand Mixtures-Silty Sand to Sandy Silt

Sands-Clean Sand to Silty Sand

Electronic Filename: C-02.DAT

Depth (ft)

Tip Resistance qt

(tsf)

80 160 240 320

Cone Size: 1.75

2.5 ft

SBTFr

MAI = 5

Sleeve Friction fs

(tsf)

1 2 3 4

Pore Pressure u2

(tsf)

0 20 40 60

Friction Ratio Rf

2 4 6 8

40.0 ft Target Depth

Joint Base Charleston B464 Retrofit North Charleston, SC

S&ME Project No: 24130012 Total Depth:

Termination Criteria:

Date:

Estimated Water Depth:

Rig/Operator:

Aug. 21, 2024

Morooka/MW | RH

C P

T R

E P

O R

T

S T

A N

D A

R D

S

B T

F R

2.

G P

J \ S

M

E .G

D T

9/

5/

Depth (ft)

101 100

Equivalent N60

80604020 qt

(tsf) u0

0 2 4 6 u2

(tsf)

Sounding ID: C-02

Sands-Clean Sand to Silty Sand

Sand Mixtures-Silty Sand to Sandy Silt

Silt Mixtures-Clay Silt to Silty Clay

Silt Mixtures-Clay Silt to Silty Clay

Sand Mixtures-Silty Sand to Sandy Silt

Sand Mixtures-Silty Sand to Sandy Silt

Sand Mixtures-Silty Sand to Sandy Silt

Sands-Clean Sand to Silty Sand

Electronic Filename: C-03.DAT

Depth (ft)

Tip Resistance qt

(tsf)

80 160 240 320

Cone Size: 1.75 3 ft

SBTFr

MAI = 5

Sleeve Friction fs

(tsf)

1 2 3 4

Pore Pressure u2

(tsf)

0 20 40 60

Friction Ratio Rf

2 4 6 8

40.1 ft Target Depth

Joint Base Charleston B464 Retrofit North Charleston, SC

S&ME Project No: 24130012 Total Depth:

Termination Criteria:

Date:

Estimated Water Depth:

Rig/Operator:

Aug. 21, 2024

Morooka/MW | RH

C P

T R

E P

O R

T

S T

A N

D A

R D

S

B T

F R

2.

G P

J \ S

M

E .G

D T

9/

5/

Depth (ft)

101 100

Equivalent N60

80604020 qt

(tsf) u0

0 2 4 6 u2

(tsf)

Sounding ID: C-03

Sands-Clean Sand to Silty Sand

Silt Mixtures-Clay Silt to Silty Clay

Sand Mixtures-Silty Sand to Sandy Silt

Silt Mixtures-Clay Silt to Silty Clay

Sand Mixtures-Silty Sand to Sandy Silt

Sand Mixtures-Silty Sand to Sandy Silt

Sand Mixtures-Silty Sand to Sandy Silt

Sands-Clean Sand to Silty Sand

Sands-Clean Sand to Silty Sand

Sand Mixtures-Silty Sand to Sandy Silt

Electronic Filename: C-04.DAT

Depth (ft)

Tip Resistance qt

(tsf)

80 160 240 320

Cone Size: 1.75 4 ft

SBTFr

MAI = 5

Sleeve Friction fs

(tsf)

1 2 3 4

Pore Pressure u2

(tsf)

0 20 40 60

Friction Ratio Rf

2 4 6 8

92.2 ft Maximum Reaction Force

Joint Base Charleston B464 Retrofit North Charleston, SC

S&ME Project No: 24130012 Total Depth:

Termination Criteria:

Date:

Estimated Water Depth:

Rig/Operator:

Aug. 21, 2024

Morooka/MW | RH

C P

T R

E P

O R

T

S T

A N

D A

R D

S

B T

F R

2.

G P

J \ S

M

E .G

D T

9/

5/

Depth (ft)

101 100

Equivalent N60

80604020 qt

(tsf) u0

0 2 4 6 u2

(tsf)

Sounding ID: C-04

Sand Mixtures-Silty Sand to Sandy Silt

Sand Mixtures-Silty Sand to Sandy Silt

Sand Mixtures-Silty Sand to Sandy Silt

Sand Mixtures-Silty Sand to Sandy Silt

Sand Mixtures-Silty Sand to Sandy Silt

Electronic Filename: C-04.DAT

Depth (ft)

Tip Resistance qt

(tsf)

80 160 240 320

Cone Size: 1.75 4 ft

SBTFr

MAI = 5

Sleeve Friction fs

(tsf)

1 2 3 4

Pore Pressure u2

(tsf)

0 20 40 60

Friction Ratio Rf

2 4 6 8

92.2 ft Maximum Reaction Force

Joint Base Charleston B464 Retrofit North Charleston, SC

S&ME Project No: 24130012 Total Depth:

Termination Criteria:

Date:

Estimated Water Depth:

Rig/Operator:

Aug. 21, 2024

Morooka/MW | RH

C P

T R

E P

O R

T

S T

A N

D A

R D

S

B T

F R

2.

G P

J \ S

M

E .G

D T

9/

5/

Depth (ft)

101 100

Equivalent N60

80604020 qt

(tsf) u0

0 2 4 6 u2

(tsf)

Sounding ID: C-04

De pt h (fe et

NOTES

0.3

2.5

4.0

DE

PO

SI

TI

O N

AL

EN

VI

RO

N M

EN

T

Co as ta l P la in

G

RA

PH

IC

SAMPLE

NO. MATERIAL DESCRIPTION

TOPSOIL

SILTY SAND (SM), liƩle Įnes, brown and gray orange, Įne grained, moist

CLAYEY SAND (SC), some Įnes, brown and gray orange, Įne grained, moist

Bore Hole terminated at 4.0 feet.

W

AT

ER

L

EV

EL

PROJECT: Joint Base Charleston B464 RetroĮt North Charleston, South Carolina

S&ME Project No. 24130012

HAND AUGER LOG: C-01.

Sheet 1 of 1

DATE: 08/19/2024 ELEVATION:

EQUIPMENT: Hand Auger DATUM: NAVD88

OPERATOR: Samuel Folmar DEPTH: 4.0 Ō

HAMMER TYPE: n/a CLOSURE: Cuƫngs DRILLING METHOD: LOGGED BY: Samuel Folmar

NOTES:

LATITUDE: 32.903826 LONGITUDE: -80.056791

SAMPLING METHOD: PROJECT COORDINATE SYSTEM - NAD 1983 StatePlane South Carolina FIPS 3900 Feet

GROUNDWATER DATE DEPTH

(FT) REMARKS

ATD 08/19/2024 Not encountered

END OF DRILLING

AFTER DRILLING

AFTER DRILLING

GROUNDWATER DEPTHS ARE NOT EXACT AND MAY VARY SUBSTANTIALLY FROM THOSE INDICATED. ATD = AT TIME OF DRILLING LL=Liquid Limit, PL = PlasƟc Limit, NMC = Natural Moisture Content, PPV = Pocket Penetrometer (tsf), PTV = Pocket Torvane (tsf) h (fe et

NOTES

0.2

2.0

4.0

DE

PO

SI

TI

O N

AL

EN

VI

RO

N M

EN

T

Co as ta l P la in

G

RA

PH

IC

SAMPLE

NO. MATERIAL DESCRIPTION

TOPSOIL

SILTY SAND (SM), liƩle Įnes, brown and tan black, Įne grained, moist

CLAYEY SAND (SC), some Įnes, brown and gray orange, Įne grained, moist

Bore Hole terminated at 4.0 feet.

W

AT

ER

L

EV

EL

PROJECT: Joint Base Charleston B464 RetroĮt North Charleston, South Carolina

S&ME Project No. 24130012

HAND AUGER LOG: C-02.

Sheet 1 of 1

DATE: 08/19/2024 ELEVATION:

EQUIPMENT: Hand Auger DATUM: NAVD88

OPERATOR: Samuel Folmar DEPTH: 4.0 Ō

HAMMER TYPE: n/a CLOSURE: Cuƫngs DRILLING METHOD: LOGGED BY: Samuel Folmar

NOTES:

LATITUDE: 32.903835 LONGITUDE: -80.056209

SAMPLING METHOD: PROJECT COORDINATE SYSTEM - NAD 1983 StatePlane South Carolina FIPS 3900 Feet

GROUNDWATER DATE DEPTH

(FT) REMARKS

ATD 08/19/2024 Not encountered

END OF DRILLING

AFTER DRILLING

AFTER DRILLING

GROUNDWATER DEPTHS ARE NOT EXACT AND MAY VARY SUBSTANTIALLY FROM THOSE INDICATED. ATD = AT TIME OF DRILLING LL=Liquid Limit, PL = PlasƟc Limit, NMC = Natural Moisture Content, PPV = Pocket Penetrometer (tsf), PTV = Pocket Torvane (tsf) h (fe et

NOTES

0.3

2.8

4.0

DE

PO

SI

TI

O N

AL

EN

VI

RO

N M

EN

T

Co as ta l P la in

G

RA

PH

IC

SAMPLE

NO. MATERIAL DESCRIPTION

TOPSOIL

SILTY SAND (SM), liƩle Įnes, brown and gray, Įne grained, moist

CLAYEY SAND (SC), some Įnes, brown and gray orange, Įne grained, moist

Bore Hole terminated at 4.0 feet.

W

AT

ER

L

EV

EL

PROJECT: Joint Base Charleston B464 RetroĮt North Charleston, South Carolina

S&ME Project No. 24130012

HAND AUGER LOG: C-03.

Sheet 1 of 1

DATE: 08/19/2024 ELEVATION:

EQUIPMENT: Hand Auger DATUM: NAVD88

OPERATOR: Samuel Folmar DEPTH: 4.0 Ō

HAMMER TYPE: n/a CLOSURE: Cuƫngs DRILLING METHOD: LOGGED BY: Samuel Folmar

NOTES:

LATITUDE: 32.903599 LONGITUDE: -80.057007

SAMPLING METHOD: PROJECT COORDINATE SYSTEM - NAD 1983 StatePlane South Carolina FIPS 3900 Feet

GROUNDWATER DATE DEPTH

(FT) REMARKS

ATD 08/19/2024 Not encountered

END OF DRILLING

AFTER DRILLING

AFTER DRILLING

GROUNDWATER DEPTHS ARE NOT EXACT AND MAY VARY SUBSTANTIALLY FROM THOSE INDICATED. ATD = AT TIME OF DRILLING LL=Liquid Limit, PL = PlasƟc Limit, NMC = Natural Moisture Content, PPV = Pocket Penetrometer (tsf), PTV = Pocket Torvane (tsf) h (fe et

NOTES

0.3

2.5

4.0

DE

PO

SI

TI

O N

AL

EN

VI

RO

N M

EN

T

Co as ta l P la in

G

RA

PH

IC

SAMPLE

NO. MATERIAL DESCRIPTION

TOPSOIL

SILTY SAND (SM), liƩle Įnes, brown and gray orange, Įne grained, moist

CLAYEY SAND (SC), some Įnes, brown and gray orange, Įne grained, moist

Bore Hole terminated at 4.0 feet.

W

AT

ER

L

EV

EL

PROJECT: Joint Base Charleston B464 RetroĮt North Charleston, South Carolina

S&ME Project No. 24130012

HAND AUGER LOG: C-04.

Sheet 1 of 1

DATE: 08/19/2024 ELEVATION:

EQUIPMENT: Hand Auger DATUM: NAVD88

OPERATOR: Samuel Folmar DEPTH: 4.0 Ō

HAMMER TYPE: n/a CLOSURE: Cuƫngs DRILLING METHOD: LOGGED BY: Samuel Folmar

NOTES:

LATITUDE: 32.903623 LONGITUDE: -80.056475

SAMPLING METHOD: PROJECT COORDINATE SYSTEM - NAD 1983 StatePlane South Carolina FIPS 3900 Feet

GROUNDWATER DATE DEPTH

(FT) REMARKS

ATD 08/19/2024 Not encountered

END OF DRILLING

AFTER DRILLING

AFTER DRILLING

GROUNDWATER DEPTHS ARE NOT EXACT AND MAY VARY SUBSTANTIALLY FROM THOSE INDICATED. ATD = AT TIME OF DRILLING LL=Liquid Limit, PL = PlasƟc Limit, NMC = Natural Moisture Content, PPV = Pocket Penetrometer (tsf), PTV = Pocket Torvane (tsf)

Fig. No.

Proj. No. 24130012

II‐1

Shear Wave Velocity Profile

AAC

Checked by:

GJC

Date: 8/21/2024

Computed by:

C-04

JBC Dormitory B464 Retrofit

North Charleston, South Carolina

0 500 1000 1500 2000 2500 3000

D ep th ft

Shear Wave Velocity (ft/sec)

Slope Method Velocity

Pseudo-interval Velocities

Assumed to 100 ft

VS,100 = 1,175 ft/s

Field Testing Procedures

Cone Penetrometer Test (CPT) Sounding

The cone penetrometer test soundings (ASTM D 5778) were performed by hydraulically pushing an electronically instrumented cone penetrometer through the soil at a constant rate. As the cone penetrometer tip was advanced through the soil, continuous readings of point stress, sleeve friction and pore water pressure were recorded and stored in the on-site computers. Using theoretical and empirical relationships, the CPT data was used to determine soil stratigraphy and estimate soil properties and parameters such as preconsolidation stress, effective stress, Young’s Modulus, friction angle and undrained shear strength.

CPT Correlations References are in parenthesis next to the appropriate equation.

General pa = atmospheric pressure (for unit normalization) u0 = hydrostatic pressure qt = corrected cone tip resistance (tsf) Bq = (u2-u0)/(qt-σv0) fs = friction sleeve resistance (tsf) Qt = (qt-σv0)/ σ’v0 Rf = 100% * (fs/qt) Fr = 100% * fs/(qt-σv0) u2 = pore pressure behind cone tip (tsf) Ic = ((3.47-logQt) +(logFr+1.22)

0.5

N-Value N60 = (qt/pa)/[8.5(1-Ic/4.6)] (6)

(6) Jefferies, M.G. and Davies, M.P., (1993), “Use of CPTu to estimate equivalent SPT N60”, ASTM Geotechnical Testing Journal, Vol. 16, No. 4

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�U� �����R�� Y��!�����*!"��

�����\�"�� Y��!�����*!"�

ORGANIC CLAYS OF MEDIUM TO

HIGH PLASTICITY, ORGANIC SILTS

PEAT, HUMUS, SWAMP SOILS WITH

HIGH ORGANIC CONTENTS

GRAVELS WITH

FINES

CLEAN SANDS

(LITTLE OR NO FINES)

SANDS WITH

FINES

LIQUID LIMIT

LESS THAN 50

LIQUID LIMIT

GREATER THAN 50

HIGHLY ORGANIC SOILS

GRAVEL

AND

GRAVELLY

SOILS

(APPRECIABLE

AMOUNT OF FINES)

(APPRECIABLE

AMOUNT OF FINES)

(LITTLE OR NO FINES)

FINE

GRAINED

SOILS

SILTS

AND

CLAYS

INORGANIC CLAYS OF HIGH

PLASTICITY

WELL-GRADED GRAVELS, GRAVEL -

SAND MIXTURES, LITTLE OR NO

FINES

SILTS

AND

CLAYS

MORE THAN 50%

OF MATERIAL IS

LARGER THAN

NO. 200 SIEVE

SIZE

MORE THAN 50%

OF MATERIAL IS

SMALLER THAN

NO. 200 SIEVE

SIZE

LETTER

MORE THAN 50%

OF COARSE

FRACTION

PASSING ON NO.

4 SIEVE

MORE THAN 50%

OF COARSE

FRACTION

RETAINED ON NO.

4 SIEVE

NOTE: DUAL SYMBOLS ARE USED TO INDICATE BORDERLINE SOIL CLASSIFICATIONS

GW

MAJOR DIVISIONS

PT

OH

CH

CLAYEY GRAVELS, GRAVEL - SAND -

CLAY MIXTURES

WELL-GRADED SANDS, GRAVELLY

SANDS, LITTLE OR NO FINES

POORLY-GRADED SANDS,

GRAVELLY SAND, LITTLE OR NO

FINES

SILTY SANDS, SAND - SILT

MIXTURES

CLAYEY SANDS, SAND - CLAY

MIXTURES

INORGANIC SILTS AND VERY FINE

SANDS, ROCK FLOUR, SILTY OR

CLAYEY FINE SANDS OR CLAYEY

SILTS WITH SLIGHT PLASTICITY

SYMBOLS

SAND

AND

SANDY

SOILS

GRAPH

INORGANIC CLAYS OF LOW TO

MEDIUM PLASTICITY, GRAVELLY

CLAYS, SANDY CLAYS, SILTY

CLAYS, LEAN CLAYS

ORGANIC SILTS AND ORGANIC

SILTY CLAYS OF LOW PLASTICITY

INORGANIC SILTS, MICACEOUS OR

DIATOMACEOUS FINE SAND OR

SILTY SOILS

MH

OL

CL

ML

SC

SM

SP

COARSE

GRAINED

SOILS

TYPICAL

DESCRIPTIONS

POORLY-GRADED GRAVELS,

GRAVEL - SAND MIXTURES, LITTLE

OR NO FINES

SILTY GRAVELS, GRAVEL - SAND -

SILT MIXTURES

SOIL CLASSIFICATION CHART

GC

GM

GP

SW

CLEAN

GRAVELS

Seismic Cone Penetrometer (SCPT) Sounding

During the conventional cone penetration soundings (ASTM D 5778), the cone penetrometer was halted at pre-specified depth increments to measure shear waves. As the probe was stopped, a shear wave was then generated at the ground surface. As the shear waves propagate through the soil, the response of geophones mounted inside the cone penetrometer is recorded with time to create a shear wave record. Several of these records were taken at different depth intervals in the sounding and arrival times for each record were compared to calculate the shear wave velocity of the soil for the given depth interval.

April 14, 2025 iv

Appendix III – Site-Specific Response Analysis

Layer

No.

Age Material Description

Thickness

(ft)

Top

Depth (ft) Vs (ft/s) PI

Unit

Weight

(pcf)

Ko f' (deg) Su (psf)

1 Loose to M. Dense Silty Sand 3 0.0 600 0 110 0.5 32 -

2 V. Loose Clayey Sand 2 3.0 600 20 100 0.5 - 800

3 M. Dense Sand 4 5.0 670 0 115 0.5 34 -

4 Loose Silty Sand 3 9.0 670 0 105 0.5 32 -

5 M. Dense to Dense Sand 2 12.0 670 0 115 0.5 34 -

6 Firm Clay & Silt 2 14.0 550 30 100 0.5 - 1000

7 5 16.0 700 0 110 0.5 34 -

8 4 21.0 860 0 110 0.5 34 -

9 Young Marl 6 25.0 1000 30 110 0.8 - 1500 - 3500

10 9 31.0 1400 30 115 0.8 - 3500 - 4000

11 160 40.0 1670 30 115 0.8 - 4000 - 6000

12 - Assumed Soft Rock - - 2500 - 140 - - -

Table III-1 - Base Model Soil Profile

Marl

M. Dense Sand & Silty Sand

Quaternary

Tertiary

Figure

M. Dense Sand

Loose to M. Dense Silty Sand

(Quaternary)

V. Loose Clayey Sand

Loose Silty Sand

M. Dense to Dense Sand

Firm Clay & Silt

M. Dense Sand & Silty Sand

Young Marl (Tertiary)

Marl

Project

No.:

24130012 Shear Wave Velocity (Vs) Profile

III-1

Date: September 2024

JBC Dormitory B464 Retrofit

North Charleston, South Carolina

0 500 1000 1500 2000 2500 3000

D e p th ft

Shear Wave Velocity (ft/s)

C-04

Base Model

Base +/- 15%

Vs Profile Extrapolated to Modeled B/C Boundary @ Depth of 200 ft

Deepest CPT Sounding Depth

FigureProject

No.:

24130012

Spectrally Matched and Target Response Spectra

BSE-2N Hazard - B/C Boundary

III-2

Date: September 2024

JBC Dormitory B464 Retrofit

North Charleston, SC

0.5

1.5

2.5

0.01 0.1 1 10

Sp ec tr al

A cc el er at io n g)

Period (s)

RSN763

RSN1078

RSN1111

RSN4876

RSN8165

Average

ASCE 41-17 - Site Class B

24130012

Spectrally Matched and Target Response Spectra

BSE-2E Hazard - B/C Boundary

III-3

Date: September 2024

JBC Dormitory B464 Retrofit

North Charleston, SC

0.2

0.4

0.6

0.8

1.2

1.4

1.6

0.01 0.1 1 10

Sp ec tr al

A cc el er at io n g)

Period (s)

RSN801

RSN1078

RSN1618

RSN4864

RSN8165

24130012

Spectrally Matched and Target Response Spectra

BSE-1E Hazard - B/C Boundary

III-4

Date: September 2024

JBC Dormitory B464 Retrofit

North Charleston, SC

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.01 0.1 1 10

Sp ec tr al

A cc el er at io n g)

Period (s)

RSN23

RSN501

RSN1757

RSN4380

RSN4554

24130012

NL Site-Specific Average ARS for Each Model

BSE-2N (MCER - 1% Risk of Collapse in 50 Years)

III-5

Date:

JBC Dormitory B464 Retrofit

North Charleston, South Carolina September 2024

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0.01 0.10 1.00 10.00

D a m p e d

S p e c te ra l A c c e le ra ti o n g

Period (sec)

BSE-2N Limit Basis (Site Class D) 80% BSE-2N Limit Basis (Site Class D) NL Vs+15% NL Vs-15% NL Su+15% NL Su-15% NL Base NL Ave.

EL Vs+15% EL Vs-15% EL Su+15% EL Su-15% EL Base EL Ave.

24130012

NL Site-Specific Average ARS for Each Model

BSE-1N (ASCE 7 Design Event - 2/3 of BSE-2N)

III-6

Date: September 2024

JBC Dormitory B464 Retrofit

North Charleston, South Carolina

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

0.01 0.10 1.00 10.00

D a m p e d

S p e c te ra l A c c e le ra ti o n g

Period (sec)

BSE-1N Limit Basis (Site Class D) 80% BSE-1N Limit Basis (Site Class D) NL Vs+15% NL Vs-15% NL Su+15% NL Su-15% NL Base NL Ave.

EL Vs+15% EL Vs-15% EL Su+15% EL Su-15%

24130012

NL & EL Site-Specific Average ARS for Each Model

BSE-2E Hazard (5% P/E in 50 Years)

III-7

Date:

JBC Dormitory B464 Retrofit

North Charleston, South Carolina October 2024

0.0

0.5

1.0

1.5

2.0

2.5

0.01 0.10 1.00 10.00

D a m p e d

S p e c te ra l A c c e le ra ti o n g

Period (sec)

BSE-2E Limit Basis (Site Class D) 80% BSE-2E Limit Basis (Site Class D) NL Vs+15% NL Vs-15% NL Su+15% NL Su-15% NL Base NL Ave.

EL Vs+15% EL Vs-15% EL Su+15% EL Su-15%

24130012

NL & EL Site-Specific Average ARS for Each Model

BSE-1E Hazard (20% P/E in 50 Years)

III-8

Date: September 2024

JBC Dormitory B464 Retrofit

North Charleston, South Carolina

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.01 0.10 1.00 10.00

D a m p e d

S p e c te ra l A c c e le ra ti o n g

Period (sec)

BSE-1E Limit Basis (Site Class D)

80% BSE-1E Limit Basis (Site Class D)

NL Vs+15%

NL Vs-15%

NL Su+15%

NL Su-15%

NL Base

NL Ave.

EL Vs+15%

EL Vs-15%

EL Su+15%

EL Su-15%

24130012

Design Horizontal Acceleration Response Spectra at Ground Surface

BSE-2N (MCER - 1% Risk of Collapse in 50 Years)

III-9

Date:

JBC Dormitory B464 Retrofit

North Charleston, South Carolina September 2024

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

0.01 0.10 1.00 10.00

D a m p e d

S p e c te ra l A c c e le ra ti o n g

Period (sec)

BSE-2N Site-Specific Design Curve

BSE-2N Limit Basis (Site Class D)

80% BSE-2N Limit Basis (Site Class D)

BSE-2N Site-Specific Simulation (NL Base) Site Specific Design ARS

SXS = 1.491 g SX1 = 1.088 g

24130012

Design Horizontal Acceleration Response Spectra at Ground Surface

BSE-1N (ASCE 7 Design Event - 2/3 of BSE-2N)

III-10

Date: September 2024

JBC Dormitory B464 Retrofit

North Charleston, South Carolina

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

0.01 0.10 1.00 10.00

D a m p e d

S p e c te ra l A c c e le ra ti o n g

Period (sec)

BSE-1N Site-Specific Design Curve

BSE-1N Limit Basis (Site Class D)

80% BSE-1N Limit Basis (Site Class D)

BSE-1N Site-Specific Simulation (NL Base) Site Specific Design ARS

SXS = 0.994 g SX1 = 0.725 g

24130012

Design Horizontal Acceleration Response Spectra at Ground Surface

BSE-2E Hazard (5% P/E in 50 Years)

III-11

Date:

JBC Dormitory B464 Retrofit

North Charleston, South Carolina October 2024

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

0.01 0.10 1.00 10.00

D a m p e d

S p e c te ra l A c c e le ra ti o n g

Period (sec)

BSE-2E Site-Specific Design Curve

BSE-2E Limit Basis (Site Class D)

80% BSE-2E Limit Basis (Site Class D)

BSE-2E Site-Specific Simulation (NL Avg)

Site Specific Design ARS SXS = 1.284 g SX1 = 0.459 g

24130012

Design Horizontal Acceleration Response Spectra at Ground Surface

BSE-1E Hazard (20% P/E in 50 Years)

III-12

Date: September 2024

JBC Dormitory B464 Retrofit

North Charleston, South Carolina

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.01 0.10 1.00 10.00

D a m p e d

S p e c te ra l A c c e le ra ti o n g

Period (sec)

BSE-1E Site-Specific Design Curve

BSE-1E Limit Basis (Site Class D)

80% BSE-1E Limit Basis (Site Class D)

BSE-1E Site-Specific Simulation (EL Base)

Site Specific Design ARS SXS = 0.426 g SX1 = 0.079 g