ATTCH 10_Geotechnical Exploration and Evaluation Report (2024-08-26).pdf

© 2024 Yogi Kwong Engineers, LLC

FINAL SUBMITTAL

Preliminary Geotechnical Exploration and Evaluation Report

F-22 Plus-Up: Corrosion Control B3407 Structural Upgrades and Repairs

Joint Base Pearl Harbor-Hickam Honolulu, Oahu, Hawaii

Prepared for :

Orion Engineers & Associates 1003 Bishop Street, Suite 2020 Honolulu, Hawaii 96813

August 2024

Prepared by:

YOGI KWONG ENGINEERS

677 Ala Moana Blvd., Suite 710 Honolulu, Hawaii 96813

YKE Project No. 21015

August 26, 2024

Mr. Aren Cleven, P.E.

Orion Engineers & Associates 1003 Bishop Street, Suite 2020 Honolulu, HI 96813

Subject: Final Submittal

Preliminary Geotechnical Exploration and Evaluation Report F-22 Plus-Up: Corrosion Control B3407 Structural Upgrades and Repairs Joint Base Pearl Harbor-Hickam Honolulu, Oahu, Hawaii

Dear Mr. Cleven:

Yogi Kwong Engineers, LLC is pleased to submit this Final Submittal of our Preliminary Geotechnical Exploration and Evaluation Report for the F-22 Plus-Up: Corrosion Control B3407 project for your use. Our geotechnical engineering services were performed in general accordance with our revised proposal dated July 14, 2021 and subconsultant work order FSB-YKE-001.

We appreciate the opportunity to provide these services to Orion Engineers and Associates. If you have any questions regarding this letter and the attached report, please do not hesitate to contact us.

Very truly yours, Yogi Kwong Engineers, LLC

Kealohi Sandefur, P.E. Eva Ng Principal Principal

This work was prepared by me or under my supervision.

License expires on April 30, 2026

TABLE OF CONTENTS

FINAL SUBMITTAL i F-22 Plus-Up: Corrosion Control B3407

© 2024 Yogi Kwong Engineers, LLC

1.0 INTRODUCTION

1.1 Project Understanding

1.2 Purpose and Scope of Services

1.3 Exclusions

2.0 GEOTECHNICAL EXPLORATION

2.1 Field Exploration

2.2 Laboratory Testing

3.0 SITE SURFACE AND SUBSURFACE CONDITIONS

3.1 General Site Surface Conditions

3.2 Regional Geology

3.3 Local Geologic Units

3.3.1 Existing Pavement

3.3.2 Fill

3.3.3 Lagoonal Deposits

3.3.4 Coralline Deposits

3.3.5 Coral Reef Limestone

3.3.6 Intercalated Coral Reef Limestone and Coralline Deposits

3.3.7 Volcanic Tuff

3.4 Groundwater Conditions

4.0 PRELIMINARY EVALUATION OF LIQUEFACTION POTENTIAL

4.1 IBC Seismic Site Classification and Preliminary Liquefaction Assessment

4.2 Preliminary Evaluation of Mitigation Concepts

4.2.1 Deep Foundation Discussions

4.2.2 Ground Improvement by Jet Grouting Methods

5.0 LIMITATIONS

6.0 REFERENCES

TABLE OF CONTENTS

FINAL SUBMITTAL ii F-22 Plus-Up: Corrosion Control B3407

© 2024 Yogi Kwong Engineers, LLC

LIST OF FIGURES

Figure 1 Project Location Map Figure 2 Aerial Photograph of Project Location Figure 3 Regional Geology Map Figure 4 Approximate Field Exploration Location Plan

APPENDIX A FIELD EXPLORATION

A.1 Exploratory Boring and Probes A.2 Soil Sampling and Rock Coring A.3 Dynamic Cone Penetrometer Tests

APPENDIX B LABORATORY TESTING

B.1 Moisture Content and Dry Density B.2 Gradation Analysis B.3 Unconfined Compressive Strength for Rock

APPENDIX C PHOTOGRAPHS OF SELECTED SOIL AND CORE SAMPLES TAKEN DURING FIELD

EXPLORATION

LIST OF APPENDIX TABLES

Table B-1 Unconfined Compressive Strength Test Results for Rock Cores

LIST OF APPENDIX FIGURES

Figure A-1 Unified Soil Classification System Figure A-2 Description of Rock Materials Figure A-3 Log of Boring/Probe Key Figure A-4 Log of Boring B-1 Figures A-5 and A-6 Logs of Probes C-1 and C-2 Figures A-7 through A-10 DCP Test Reports Figures B-1.1 through B-1.3 Grain Size Distribution Curves

SECTION ONE INTRODUCTION

FINAL SUBMITTAL 1

F-22 Plus-Up: Corrosion Control B3407

© 2024 Yogi Kwong Engineers, LLC

1.0 Introduction

This Preliminary Geotechnical Exploration and Evaluation Report (henceforth referred to as the Geotechnical Report) was prepared by Yogi Kwong Engineers LLC (YKE) in support of the FSB JBPHH F22 Corrosion Control facility structural upgrades and repairs Project in Joint Base Pearl Harbor-Hickam, Honolulu, on the Island of Oahu, Hawaii.

The project area is shown on the Project Location Map, Figure 1, and the Aerial Photograph of Project Location, Figure 2.

1.1 PROJECT UNDERSTANDING

Based on the Scope of Work (SOW) documents provided by Orion Engineers & Associates (OEA) on June 17, 2021, subsequent discussions and e-mail correspondence, and a meeting with OEA and the project prime consultant, FSB, on July 12, 2021, we understand that the subject project currently entails development of 35% design for structural upgrades and repairs to the existing maintenance and corrosion control hangar facility (Corrosion Control B3407) and existing concrete pavement to accommodate F-22 operations within the Hawaii Air National Guard (HIANG) campus at Joint Base Pearl Harbor-Hickam (JBPHH) in Honolulu, Oahu, Hawaii.

1.2 PURPOSE AND SCOPE OF SERVICES

OEA has requested Yogi Kwong Engineers, LLC (YKE) to conduct hangar floor pavement cores and perform Dynamic Cone Penetration (DCP) testing to obtain estimated correlated California Bearing Ratios (CBR) values of the subgrade soils beneath the hangar floor at one location within each of the two (2) hangars in support of OEA’s pavement evaluations. FSB also requests YKE to conduct a geotechnical exploration and evaluate the seismic site classification, liquefaction susceptibility of the foundation subsoils and should the subsoil be found liquefiable FSB also requests that YKE provide preliminary conceptual geotechnical foundation mitigation/improvement recommendations in support of FSB’s development of 35% design of foundation improvements to mitigate foundation liquefaction concerns.

The following geotechnical scope of services was performed by YKE in general accordance with our revised fee proposal dated July 14, 2021 to Orion Engineers & Associates (OEA):

● Reviewed pertinent project information provided by OEA, FSB, and Others;

● Reviewed available documents including published historic maps, geologic maps, soil survey maps, and pertinent record geotechnical reports;

● Performed a field exploration program which included the following:

o Conducted field visits to observe the site conditions and identify field exploration locations;

o Prepared an Accident Prevention Plan (APP) for submittal to the JBPPH and/or U.S. Air Force to perform the geotechnical field exploration;

FINAL SUBMITTAL 2

F-22 Plus-Up: Corrosion Control B3407

© 2024 Yogi Kwong Engineers, LLC o Field marked one (1) boring at the southwest corner of the maintenance corrosion control facility for preliminary seismic site classification evaluation and liquefaction susceptibility screening;

o Field marked two (2) locations for pavement cores, one within each of the two existing concrete hangar floors to explore the hangar floor thickness and perform Dynamic Cone Penetration (DCP) tests in support of OEA’s pavement evaluations;

o Prepared and submitted JBPHH Dig Permit;

o Coordinated with various utility agencies and Hawaii One Call Center (HOCC) to tone and clear the boring and coring locations of subsurface utilities prior to drilling and/or excavation;

o Subcontracted YK Drilling, LLC (YKD) to perform the drilling and sampling of the exploratory borings and pavement cores;

o Drilled two (2) core holes cut through the existing hangar concrete floor slab to an approximate depth of 10 inches below the existing ground surface (bgs);

o Performed four (4) DCP tests at selected depths, within the hangar concrete floor slab core holes;

o Drilled one (1) boring to an approximate depth of 103.0 feet below the existing ground surface (bgs);

o Performed soil sampling and rock coring with visual classification during the field exploration and preserved the soil samples and rock cores for subsequent geotechnical laboratory testing;

o Conducted geotechnical laboratory tests on selected soil samples and rock cores obtained during the field exploration to aid in classifying the materials and evaluating their pertinent geotechnical index and engineering properties;

● Prepared a draft submittal Geotechnical Report summarizing the findings of our field exploration, results of our geotechnical laboratory testing, and presenting findings of our seismic site classification assessment, liquefaction potential evaluation, and preliminary foundation evaluation and mitigation/improvement concept for the structural upgrades of the existing maintenance and corrosion control facility (Corrosion Control B3407); and

● Performed a quality assurance review of this Geotechnical Report by James Kwong, Ph.D., P.E., Principal Engineer.

1.3 EXCLUSIONS

The following services are specifically excluded from the scope of services for YKE on this project:

● A Site-Specific Ground Motion evaluation such as discussed in Section 21 of ASCE 7- 16 is not included in our scope and fee;

FINAL SUBMITTAL 3

F-22 Plus-Up: Corrosion Control B3407

© 2024 Yogi Kwong Engineers, LLC

● General civil engineering, topographic surveying, hydraulic engineering, structural engineering, corrosion engineering, construction permits, and archeological and historic preservation survey/evaluation and/or monitoring;

● Environmental engineering evaluation and assessment of contaminated soils and groundwater. The geotechnical exploration and evaluation presented in this proposal is not intended to investigate potential presence of hazardous materials at the site. The equipment, techniques, and personnel used to perform a geo-environmental exploration differ substantially from those applied in a geotechnical engineering exploration, and typically cannot be performed at our geotechnical bore holes;

● Pavement evaluations;

● Development of recommendations for finalization of design in support of construction bidding documents; and

● Attendance of construction pre-bid conference and site visit.

SECTION TWO GEOTECHNICAL EXPLORATION

FINAL SUBMITTAL 4

F-22 Plus-Up: Corrosion Control B3407

© 2024 Yogi Kwong Engineers, LLC

2.0 Geotechnical Exploration

2.1 FIELD EXPLORATION

The field exploration included the drilling and sampling of one exploratory boring (B-1) and two pavement core holes (Probes C-1 and C-2). The boring was performed between January 25, 2022 and January 28, 2022 and drilled to the approximate depth of 103 feet below ground surface. The pavement core holes were performed on January 25, 2022 and were followed by hand auger excavation to approximate depths of 2.4 to 3.0 feet below existing ground surface.

Due to head room restriction and the depth of the boring, Boring B-1 was drilled outside the southwest corner of the existing maintenance and corrosion control facility. The pavement cores were drilled within the existing maintenance and corrosion control facility where Probe C-1 was located at the southwest corner while Probe C-2 was drilled near the northwest corner. The approximate locations of Boring B-1 and Cores/Probes C-1 and C-2 are shown on the Approximate Field Exploration Location Plan, Figure 4. The Log of Boring/Probes are shown in Appendix A.

A detailed description of the procedures used to drill and sample/core the exploratory borings and probe/cores are provided in Appendix A and on the Log of Boring/Probes.

Within the core/probe holes, United States Army Corps of Engineers (USACE) dynamic cone penetrometer (DCP) tests were performed down to the approximate depths of 2.4 to 3.0 feet bgs at approximate 0.5-foot intervals and using a hand auger to obtain soil samples. The DCP tests were performed in accordance with ASTM D6951 where the DCP blow counts and cone tip penetration were recorded and converted to DCP indices. The DCP indices were then correlated to estimated California Bearing Ratio (CBR) values using equations developed by the USACE for “all soils except for CL soils below CBR 10 and CH soils,” which are provided in ASTM D6951. A more detailed description of the procedures used to perform the DCP tests are provided in Appendix A.

Refer to Figures A-7 through A-10 in Appendix A for the DCP test reports. Based on the DCP results, the pavement subgrade has a correlated estimated CBR value from 6 to 62%.

2.2 LABORATORY TESTING

Geotechnical laboratory tests were conducted on selected soil samples and core samples recovered during the field exploration to evaluate the engineering properties of the soils and rock encountered.

These laboratory tests included moisture content, dry density, grain size distribution, and unconfined compressive strength (UCS) for coral reef and tuffaceous rock cores. The UCS tests on the cores were conducted by Construction Engineering Labs, Inc. in Pearl City, Hawaii. All other geotechnical laboratory tests were conducted at YKE’s laboratory in Honolulu, Hawaii.

A description of the laboratory test procedures and results of the completed tests are presented on the log of boring at appropriate sample depth and in Appendix B.

SECTION THREE SITE SURFACE AND SUBSURFACE CONDITIONS

FINAL SUBMITTAL 5

F-22 Plus-Up: Corrosion Control B3407

© 2024 Yogi Kwong Engineers, LLC

3.0 Site Surface and Subsurface condit ions

3.1 GENERAL SITE SURFACE CONDITIONS

The project area is located at the maintenance and corrosion control facility (Corrosion Control B3407) in Joint Base Pearl Harbor-Hickam, on the Island of Oahu, Hawaii (Figure 1). The project site is located within and around the corrosion control facility which is adjacent to the F-22 LO/Composite repair facility (Figure 2).

The existing corrosion control facility is accessible from a gate that is located approximately 290 feet southwest of the intersection between Worchester Avenue and Mamala Bay Drive (Figure 2).

The existing structure is founded on spread footings (Shigemura, Lau, Sakanashi, Higuchi, and Associates, 1994). The hangar floor is paved with concrete and contains underground utilities (Shigemura, Lau, Sakanashi, Higuchi, and Associates, 1994).

3.2 REGIONAL GEOLOGY

The Island of Oahu was built by two (2) shield volcanoes, the older Waianae volcano built of the Waianae Volcanic series in the west, and the younger Koolau volcano built of the Kailua Volcanic series in the east. Following a hiatus of volcanic activity of approximately 1 million years, the island experienced a rejuvenation stage of eruptions. Scattered sporadically above the Koolau and Waianae Mountains are lava flows and vent deposits of the rejuvenated stage of Hawaiian volcanism, the Honolulu Volcanics (Qot). The Honolulu Volcanics erupted along rift zones and vents through the Waianae and Koolau mountains; deposited tuffaceous ash extending miles from their eruptive source such as the tuff cone deposits (Qot) which is mapped as a near surface deposit approximately a mile and a half inland from the project area (Regional Geology Map, Figure 3).

Sherrod et al. (2007) indicated approximately 120 to 130 thousand years ago the sea level rose during the interglacial period and calcareous reef rock and marine sediment (Qcrs) formed above the present day sea level and within the vicinity of the project area (see Figure 3). The sea level rose as high as 95 feet above present day levels during the Kaena High Stand (Stearns and Vaksviks, 1935). The resulting marine-coral reef depositional environment is highly complex, with intercalating coral reef limestone ledges, coralline deposits, and back reef lagoonal deposits forming at various sea level stands that are usually highly variable in all directions.

More recently, vast areas of fill were placed during the development of the adjacent Honolulu International Airport, which is noted as Qf in Figure 3.

Based on the Regional Geology Map in Figure 3, the site is located in an area mapped at a transition between fills (Qf) and Beach Deposits (Qbd).

FINAL SUBMITTAL 6

F-22 Plus-Up: Corrosion Control B3407

© 2024 Yogi Kwong Engineers, LLC

3.3 LOCAL GEOLOGIC UNITS

The subsurface conditions discussed below are based on our interpretation of the subsoil data obtained from YKE’s field exploration conducted for this project, which are supplemented by available record geotechnical data adjacent structure (PGE, 2009), published geologic and soil survey maps, and YKE’s general experience in this area.

More detailed descriptions of the subsurface conditions encountered in the YKE borings and probes are presented on the Logs of Borings and Probes in Appendix A. Selected photographs of the soil samples and pavement cores taken are shown in Appendix C.

Based on the geologic mapping by Sherrod et al. (2007), exploratory boring B-1 and DCP and hand auger probes C-1 and C-2 and the field and laboratory testing data obtained by this study, the subsoil conditions encountered below the existing pavement at our explored locations can be generalized into six (6) local geologic units, namely Fills, Lagoonal Deposits, Coralline Deposits, Coral Reef Limestone, Intercalated Coral Reef Limestone and Coralline Deposits, and Volcanic Tuff as further discussed below:

3.3.1 EXISTING PAVEMENT

The concrete pavement cores at the two core locations within the Corrosion Control B3407 Hangar measured 9.5 and 10 inches in thickness. Refer to Log of Probes C-1 and C-2 in Appendix A for more details.

3.3.2 FILL

Fill materials were encountered below the concrete pavement in Boring B-1 and Probes C-1 and C-2 and extended to approximate elevation of 0.5 feet MSL (10.0 feet bgs) in Boring B-1 and through the explored depths of 2.4 to 3.0 feet bgs in Probes C-1 and C-2.

The Fill unit for Boring B-1 and Probes C-1 and C-2 consist primarily of medium dense, brown to gray silty gravel with sand and medium dense, tannish brown to brown with tan specks silty sand with coralline gravel. Medium dense, tan poorly graded sand with gravel and stiff, brown mottled with tan elastic silt with coralline gravel Fill were also encountered within Boring B-1. Brown poorly graded gravel with silt and sand; and brown with tan specks elastic silt with gravel Fill was also encountered within Probe C-2.

A summary of the field sampling blow counts and results of selected laboratory tests performed on Fill soils are presented below:

FINAL SUBMITTAL 7

F-22 Plus-Up: Corrosion Control B3407

© 2024 Yogi Kwong Engineers, LLC

Table 1 – Fill: Summary of Blow Counts and Laboratory Test Results

No. of samples/tests Range Average

SPT sampler blow counts per foot (excluding refusal) 3 12 to 16 14

SPT sampler refusal 0 out of 3 total samples

Modified California sampler blow counts per foot (excluding refusal) 2 21 and 27 24

Modified California sampler refusal 0 out of 2 total samples

Moisture Contents, % 4 10 to 28 18

Dry Densities, pcf1 2 90 and 93 92

Grain Size Distribution

Gravel, %

52 and 67 60

Sand, % 26 N/A

Fines, % 7 and 22 15 1 pounds per cubic foot.

3.3.3 LAGOONAL DEPOSITS

Lagoonal Deposits were encountered beneath the Fill layer in Boring B-1 between the approximate elevations of -0.5 and -12.5 feet MSL (11.0 and 23.0 feet bgs).

The Lagoonal Deposits consist primarily of very loose to medium dense, grayish to tan silty coralline and trace basalt gravel to silty sand with shells and cobbles; and soft, grayish tan sandy lean clay.

A summary of the field sampling blow counts and selected results of laboratory tests performed on Lagoonal Deposit soils are presented below:

FINAL SUBMITTAL 8

F-22 Plus-Up: Corrosion Control B3407

© 2024 Yogi Kwong Engineers, LLC

Table 2 – Lagoonal Deposits: Summary of Blow Counts and Laboratory Test Results

No. of samples/tests Range Average

SPT sampler blow counts per foot (excluding refusal) 3 3 to 9 5

SPT sampler refusal 0 out of 4 total samples

Modified California sampler blow counts per foot (excluding refusal) 4 4 to 30 12

Modified California sampler refusal 0 out of 4 total samples

Moisture Contents, % 5 26 to 40 33

Dry Densities, pcf1 2 86 and 97 92

Grain Size Distribution

3 to 43 30

Sand, % 25 to 47 37

Fines, % 15 to 66 34 1 pounds per cubic foot.

3.3.4 CORALLINE DEPOSITS

Coralline Deposits were encountered beneath the Lagoonal Deposits and intercalated with coral reef limestone in Boring B-1 at various depths with thicker deposits encountered between approximate elevations -12.5 to -54.5 feet MSL (23.0 to 65.0 feet bgs) and also underlying the Volcanic Tuff from -64.5 feet MSL to the bottom of the boring at -92.5 feet MSL (75.0 to 103.0 feet bgs); see Appendix A for more details.

The Coralline Deposits consist primarily of medium dense, tan poorly graded coralline gravel with silt, sand, and cobbles; loose to medium dense, tan to brownish gray silty coralline gravel with sand and coralline cobbles; medium dense, tan poorly graded coralline sand with gravel; and medium dense to very dense, tan silty coralline sand with gravel and cobbles.

A summary of the field sampling blow counts and selected results of laboratory tests performed on Coralline Deposit soils are presented below:

FINAL SUBMITTAL 9

F-22 Plus-Up: Corrosion Control B3407

© 2024 Yogi Kwong Engineers, LLC

Table 3 – Coralline Deposits: Summary of Blow Counts and Laboratory Test Results

No. of samples/tests Range Average

SPT sampler blow counts per foot (excluding refusal) 10 15 to 53 24

SPT sampler refusal 0 out of 10 total samples

Modified California sampler blow counts per foot (excluding refusal) 7 10 to 108 44

Modified California sampler refusal 1 out of 8 total samples

Moisture Contents, % 10 18 to 31 23

Dry Densities, pcf1 6 84 to 100 92

Grain Size Distribution

34 to 78 55

Sand, % 16 to 51 32

Fines, % 6 to 17 13 1 pounds per cubic foot.

3.3.5 CORAL REEF LIMESTONE

Coral Reef Limestone was encountered intercalated with the Coralline Deposits both above and below the Volcanic Tuff in Boring B-1. As mentioned in Section 3.2 Regional Geology, the coral reef depositional environment is highly complex and are usually highly variable in all directions as exhibited by the variable thicknesses of coral reef limestone ranging between 2 to 4 feet and frequently interspersed with pockets or lenses of Coralline Deposits.

The Coral Reef Limestone units encountered in Boring B-1 are described as a soft rock material that is moderately to occasionally fractured. Core runs performed in Coral Reef Limestone typically have measured core recovery and rock quality designation of 100%.

3.3.6 INTERCALATED CORAL REEF LIMESTONE AND CORALLINE DEPOSITS

Coral Reef Limestone and Coralline Deposit layers were closely intercalated between approximate elevations -16.5 to -29.5 and -72.5 to -84.5 feet MSL (27 to 40 and 83 to 95 feet bgs) in Boring B- 1.The Intercalated Coral Reef Limestone and Coralline Deposits contained dense to very dense, tan to grayish tan silty coralline gravel with sand and coralline cobbles; medium dense to dense, FINAL SUBMITTAL 10

F-22 Plus-Up: Corrosion Control B3407

© 2024 Yogi Kwong Engineers, LLC weakly to moderately cemented tan to off-white silty coralline sand with gravel; and soft to hard, highly to moderately fractured off-white to tan coral reef limestone.

A summary of the field sampling blow counts, core recovery, rock quality designation, and selected results of laboratory tests performed on Intercalated Coral Reef Limestone and Coralline Deposit soils are presented below:

Table 4 – Intercalated Coral Reef Limestone and Coralline Deposits: Summary of Blow Counts and Laboratory Test Results

No. of samples/tests Range Average

SPT sampler blow counts per foot (excluding refusal) 4 18 to 71 43

SPT sampler refusal 0 out of 4 total samples

Modified California sampler blow counts per foot (excluding refusal) 1 56 N/A

Modified California sampler refusal 1 out of 2 total samples

Moisture Contents, % 2 22 and 34 28

Dry Densities, pcf1 2 60 and 107 84

Core Recovery, % 5 49 to 100 89

Rock Quality Designation, % 5 0 to 54 37

Unconfined Compressive Strength, psi2 1 374 N/A 1 pounds per cubic foot. 2 pounds per square inch.

3.3.7 VOLCANIC TUFF

Volcanic Tuff was encountered between the approximate elevations of -54.5 and -64.5 feet MSL (65 and 75 feet bgs) in Boring B-1.

The Volcanic Tuff encountered in Boring B-1 contained a 2-foot layer of dense to very dense, tan and dark brown silty sand with gravel overlying medium hard, slightly weathered, moderately to occasionally fractured dark brown and gray tuffaceous rock. The laboratory testing on a sample of tuffaceous rock had a dry unit weight of 117 pcf and a water content of 11%. The tuffaceous rock cores both measured 100% core recovery and a rock quality designation (RQD) of 61 and

FINAL SUBMITTAL 11

F-22 Plus-Up: Corrosion Control B3407

© 2024 Yogi Kwong Engineers, LLC

94% (average 78%). One rock core sample was tested for its unconfined compressive strength (UCS) and exhibited a UCS of 2,184 psi.

3.4 GROUNDWATER CONDITIONS

During the field exploration, groundwater was encountered in Boring B-1 and ranged from approximately 8.6 to 9.3 feet bgs in depth, or at approximately 1.3 to 1.9 feet MSL in elevation.

The groundwater level at the project site is expected to fluctuate with tidal changes due to its close proximity to the ocean.

SECTION FOUR PRELIMINARY EVALUATION OF LIQUEFACTION POTENTIAL

FINAL SUBMITTAL 12

F-22 Plus-Up: Corrosion Control B3407

© 2024 Yogi Kwong Engineers, LLC

4.0 Preliminary Evaluation of Liquefaction Potential

4.1 IBC SEISMIC SITE CLASSIFICATION AND PRELIMINARY LIQUEFACTION ASSESSMENT

Based on Section 1613.2.2 of the International Building Code’s (IBC, 2018) site class definitions, the site shall be classified as Seismic Site Class A, B, C, D, E or F in accordance with Chapter 20 of the ASCE Standard 7-16 (ASCE, 2016). Based on our geotechnical exploratory Boring B-1 sampler blow counts, a preliminary calculation of the Seismic Site Class resulted in a Seismic Site Class of E. However, in accordance with ASCE 7-16 Section 20.3.1, sites containing “soils vulnerable to potential failure or collapse under seismic loading, such as liquefiable soils,” shall be classified as Seismic Site Class F. Therefore, a preliminary liquefication screening was performed to determine if the project site should be classified as Seismic Site Class E or F.

Liquefaction is a soil behavior or phenomenon in which a soil loses a substantial amount of its shear strength due to the build-up of excess pore-water pressure, which is most commonly generated by strong earthquake ground shaking. In general, soils most susceptible to liquefaction are saturated, loose, uniformly graded, fine-grained sands containing little or no cohesive fines.

Based on the geotechnical exploration and laboratory test data, several zones of very loose to medium dense saturated silty sand, gravel, and low plasticity fine-grained materials were encountered at various depths in Boring B-1, therefore a liquefaction assessment was performed.

For liquefaction screening, we considered a peak ground acceleration of 0.45g which is calculated using the procedures in ASCE 7-16 for Site Class E and a magnitude 6.23 earthquake which roughly corresponds to a return period of about 975 years. The preliminary liquefaction analysis was performed using LiquefyPro, a software by Civiltech Software and is based on the NCEER Workshop and SP117 methods, and the results are presented below in Insert 1.

FINAL SUBMITTAL 13

Insert 1: Boring B-1 Preliminary Liquefaction Analysis.

Due to the coral reef depositional environment being highly complex and are usually highly variable in all directions, it is noted that the 2-foot Coral Reef Limestone unit encountered in Boring B-1 was excluded from this preliminary soil liquefaction analysis. Based on the preliminary soil liquefaction analysis performed, the lagoonal and coralline deposits encountered in Boring B-1 contain liquefiable soils (Factor of Safety <1) between approximately 12 to 23 feet bgs and 39 to 63 feet bgs (Insert 1).

The result of the analysis also indicates that an estimated potential liquefaction induced ground settlement on the order of 12 inches is calculated at the Boring B-1 location, based on the conditions considered and the methods used.

FINAL SUBMITTAL 14

F-22 Plus-Up: Corrosion Control B3407

© 2024 Yogi Kwong Engineers, LLC

It should be noted that the above liquefaction screening analysis is considered preliminary and, if necessary, further evaluation can be performed since the preliminary analysis utilize peak ground acceleration calculated for Site Class E based on procedures in ASCE 7-16 Chapter 11 for preliminary screening analysis. Since the site is susceptible to liquefaction, based on the preliminary liquefaction analysis, a site response analyses would be required by ASCE 7-16 Chapter 11 to further evaluate the propagation of ground acceleration through a liquifiable soil stratum, and potential amplification of the peak ground acceleration.

It is also noted that the current available SPT liquefaction correlations are not known to have included coralline materials such as those present at this site. Chengjie et al. [2013] has reported that coral sands having physical properties and motion characteristics which are believed to differ from the soil types used to develop the current SPT based liquefaction correlations. In the absence of further studies which develop SPT correlations for coralline soils, we have used the SPT based correlations currently available.

Based on past project experience the extent, thickness and characteristics of the very loose to medium dense Lagoonal Deposits can change over horizontal distance, and typically the gradation and densities of the coralline deposits can vary significantly in all directions within short distances.

It would be prudent to perform a more detailed supplemental geotechnical investigation to delineate the probable location and extent of the potentially liquefiable soil zones under the subject facilities should further evaluation of site response analysis and design of foundation support/ground improvement to mitigate against potential soil liquefaction at this site is necessary.

4.2 PRELIMINARY EVALUATION OF MITIGATION CONCEPTS

Based on the available as-built drawings, it is our understanding that the corrosion control facility is founded on spread footings that are situated as shown in the below Insert 2 with the dimensions presented in Insert 3.

FINAL SUBMITTAL 15

Insert 2: Fuel System Maintenance/Corrosion Control Facility Foundation Plan (Shigemura, Lau, Sakanashi, Higuchi and Associates, 1994).

Insert 3: Fuel System Maintenance/Corrosion Control Facility Spread Footing Schedule

(Shigemura, Lau, Sakanashi, Higuchi and Associates, 1994).

As discussed in Subsection 4.1, based on the available information and preliminary liquefaction analysis performed, the project site is prone to potential soil liquefication and ground settlement during the considered earthquake and thus, from a geotechnical standpoint, we believe that building’s spread footings would require underpinning with deeper foundations or ground improvement to mitigate against potential excessive ground settlements in the event of a significant earthquake and the associated potential structural damage.

FINAL SUBMITTAL 16

F-22 Plus-Up: Corrosion Control B3407

© 2024 Yogi Kwong Engineers, LLC

4.2.1 DEEP FOUNDATION DISCUSSIONS

Augercast in-place piles (ACIP), drilled shaft caissons, driven piles, and micropiles were considered as potential deep foundation concepts to support the Building’s spread footings, by extending the hangar’s foundation support below the liquefiable soils and onto more competent volcanic tuff. However, in our opinion, the deep foundation types which are not anticipated to be appropriate to provide structural upgrades to the Corrosion Control Building B3407 are briefly discussed below.

• ACIP typically involves the use of a 12 to 24-inch continuous flight hollow-stem augers to pre-drill to the design pile tip elevation using large augercast pile rig with vertical mast higher than the depth of the deep foundation, to depths of approximately 67 to 70 feet bgs.

Grout is pumped to the tip of the hollow stem augers as the augers are slowly withdrawn from the pre-drilled hole. Steel reinforcement is then lowered into the wet column to provide the required structural reinforcement. There is insufficient head room for a large auger pile rig to work inside the facility. Also, ACIP are typically designed to develop their capacity through skin friction along the length of the pile. Due to the presence of a deep deposit of liquefiable coralline sands which overlay the Volcanic Tuff, an ACIP is expected to require embedment in the underlying Volcanic Tuff to develop pile capacity in this bearing layer. Furthermore, this liquefiable zone is not expected to provide skin friction during the considered seismic event. ACIP pile capacity is expected to require embedding the ACIP pile tip on or into the Volcanic Tuff rock. In addition, the upper portion of the ACIP pile length embedded in the liquefiable coralline soils would experience in significant down drag forces should the site experience liquefaction settlement.

• Drilled shaft caissons can be constructed with smooth steel casings to mitigate the down-drag forces associated with liquefaction settlement of the upper coralline soils and can also be more easily advanced into the Tuff Rock using core barrels to develop its capacity in this bearing layer. However, similar to installation of augercast piles, installation of drilled caissons are expected to be limited to the building exterior and involve offsetting caisson from the footing which is expected to require more extensive structural design of the foundation connection due to the on-sided offset caisson and the need to transfer the loads and induced bending moments. In addition, caisson drilling and installation of reinforcement involves the use of cranes and drill rigs with tall masts which may be complicated given the project sites’ proximity within FAA airspace.

• Driven piles are expected to have similar challenges as drilled caissons in that their installation would be limited to building exterior and would also involve offsetting the piles from the footings. In addition, the layers of coral reef rock are expected to require

FINAL SUBMITTAL 17

F-22 Plus-Up: Corrosion Control B3407

© 2024 Yogi Kwong Engineers, LLC predrilling to break up these hard zones that may obstruct pile installation or require stronger pile hammers which could induce vibration settlements during construction.

Since micropiles drill rig and in-hole tools can be adapted to low head room situations, micropiles are considered a potentially viable option to underpin the building’s footings based on the following considerations:

• Micropiles can be installed with smaller drill rigs and in low headspace areas which facilitates installation both inside and outside of the hangar allowing for a more symmetric underpinning of the footings. Micropiles also do not require the use of cranes.

• Micropiles can be installed in close proximity to the building and footings, and can be structurally connected to the footings by steel brackets and/or other reinforcement.

• Micropile drill rigs frequently use casing and percussive drilling suitable to socket the miropiles into the Tuff Rock foundation layer. Casings can be left in place through the upper liquefiable coralline deposits to reduce down drag loads associated with liquefaction induced settlement.

However, micropiles are slender and considering the nearly 70-foot depth to the Tuff Rock layer, we anticipate that larger diameter micropiles will likely be required based on their bending stiffness. We have performed preliminary pile capacity analyses for 7.5 and 9.5-inch diameter micropiles based on the available information. The project’s structural engineer should evaluate the feasibility of using micropiles only to underpin the existing shallow spread footings as part of the structural upgrades.

Based on Federal Highway Administration (FHWA) NHI Course No. 132078 Micropile Design and Construction Reference Manual Table 5-3 (FHWA, 2005), we have calculated preliminary axial capacities for 7.5-inch and 9.5-inch micropiles assuming that the typical grout-to-ground bond for Volcanic Tuff is approximately 55 psi and micropiles be installed to 75 feet bgs, into the volcanic tuff unit. Based on this preliminary design assumption, we recommend pile capacities of 120 kips and 150 kips for the 7.5- and 9.5-inch diameter micropiles respectively.

Based on past project bid prices, we estimate that micropiles of this size and length may cost between $450 to $550 per linear foot, in the current construction market resulting in a cost on the order of $33,000 and $41,000 per micropile; excluding any structural connection to the existing foundations, and any constraints associated with working inside the facilities using compressed air and the need to control grout and drilling spoil returns. Furthermore, based on discussions with the industry we understand that construction material costs are very volatile in the current market conditions and material costs have been experiencing rapid and dramatic escalations. We

FINAL SUBMITTAL 18

F-22 Plus-Up: Corrosion Control B3407

© 2024 Yogi Kwong Engineers, LLC anticipate that the required number micropiles may be controlled by seismic lateral load and the structural demands on the relatively slender miropiles which are unknown at this time.

Should the design be developed past 35% design, a site response analysis will likely be necessary and require further evaluation of the lateral loads and bending moments on the micropiles.

Additional supplemental geotechnical exploration will also be required to obtain subsurface information in the building area to supplement the boring information at B-1, in support of the site response analysis, and evaluation of the depths and extent of the liquefiable soils beneath the existing facilities.

Should the further evaluations find that the seismic demands results in excessive lateral loads and bending moments induced on the relatively slender micropiles the project design team could consider jet grout stabilization of the very loose to medium dense Lagoonal deposit and loose to medium dense coralline materials above the Volcanic Tuff, to create a shallower jet grout stabilized bearing stratum where the micropiles can develop their capacities by socketing the piles into jet grouted zones.

4.2.2 GROUND IMPROVEMENT BY JET GROUTING METHODS

Alternatively, jet grouting rigs with adaptations to low head room situations can be used to improve the ground conditions below the existing footings, and underpin the footings by installing jet grouted columns, approximately 36 to 40-inch diameter with target jet grout strength of at least 300 psi, from below the stiff or dense near surface fills to the volcanic tuff layer, for conditions such as those encountered in Boring B-1. The jet grout columns do not need to be overlapping but it will need to be continuous down to the volcanic tuff and closely spaced such that it covers most of the surface area under the footings. Some inclined jet grout columns may be necessary to improve the liquefiable soils under the larger footings. The extent, location and depths of ground improvement should be further evaluated with more detailed supplemental geotechnical data.

Based on past project bid prices, we estimate that jet grouting column of this size and length may cost between $350 to $450 per linear foot, in the current construction market, resulting in a cost on the order of $26,000 and $33,000 per jet grout column; excluding any constraints associated with working inside the facilities and the need to control grout and drilling spoil returns.

Furthermore, based on discussions with the industry we understand that construction material costs are very volatile in the current market conditions and material costs have been experiencing rapid and dramatic escalations. Similar to micropiles, we anticipate that the required number of jet grout columns may also be controlled by seismic lateral load and the structural demands on the jet grout columns which are unknown at this time.

SECTION FIVE LIMITATIONS

FINAL SUBMITTAL 19

F-22 Plus-Up: Corrosion Control B3407

© 2024 Yogi Kwong Engineers, LLC

5.0 Limitations

The geotechnical findings and recommendations presented in this Preliminary Geotechnical Report are based on the assumption that the scope of the design is a preliminary 35% mitigation concept and not final design.

Our preliminary analysis is based on the data obtained from our preliminary geotechnical exploration with the objective to evaluate if there is potential liquefaction and, if present, develop a preliminary mitigation concept. This Preliminary Geotechnical Report presents our preliminary opinion of the encountered subsurface conditions. While the properties of the materials encountered in the field are expected to be within the ranges discussed for the vicinity of the boring and probes, the actual distribution of materials encountered will likely vary from those discussed in this report. If final design is pursued, further exploration will be needed to refine the geologic profile across the entire project site. The descriptions and discussions of encountered subsurface conditions presented in this report are intended to assist Orion Engineers & Associates (OEA) and OEA’s design team in preliminary design considerations to mitigate potential soil liquefaction. As mentioned in the report, further exploration and geotechnical evaluation is needed to support further development of mitigation concepts against potential soil liquefaction in a significant earthquake in support of final design, if pursued.

This Preliminary Geotechnical Report was prepared for use by OEA and OEA’s design team in accordance with generally accepted geotechnical engineering principles and practices. The preliminary geotechnical opinions and recommendations given in this report are based on our evaluation of the data collected for this project. Additive conclusions or recommendations made from this data by others for other uses are their responsibility.

No warranty is included, either expressed or implied, that the actual conditions encountered will conform exactly to the conditions described herein. Our services were provided in a manner consistent with the level of care and skill ordinarily exercised by other geotechnical consultants under similar circumstances. No other representation is intended or implied.

Note that the scope of service associated with this report was designed solely to achieve the objectives, schedule, budget, and risk-management preferences OEA and OEA’s design team established for this project. Except OEA and OEA’s design team, no one should use or rely on this report. No one, not even OEA and OEA’s design team, should use or rely on this report for any extension of this project, for any other project, or for any other purpose. Unless YKE verifies in writing that it has reviewed the report and that the proposed use, reuse or reliance is acceptable, any such use, reuse, or reliance is prohibited and shall be at the user's, reuser's, or relier's sole risks.

SECTION SIX REFERENCES

FINAL SUBMITTAL 20

F-22 Plus-Up: Corrosion Control B3407

© 2024 Yogi Kwong Engineers, LLC

6.0 References

American Society of Civil Engineers (ASCE), Standard 7, 2016. “Minimum Design Loads and Associated Criteria for Buildings and Other Structures.”

Chengjie, Z., Peidong, L.U., Yanhong, W., 2013. “Experiment Study on Physical Properties and Motional Characteristics of Coral Sand.” International Conference on Asian and Pacific Coasts.

Federal Highway Administration (FHWA), 2005. “NHI Course No. 132078 Micropile Design and Construction Reference Manual.” U.S. Department of Transportation, FHWA NHI-05-039.

Google Earth, 2019, Pearl Harbor, Oahu, Hawaii Accessed in 2022.

International Code Council, 2018. “International Building Code, Fifth Edition.”

Pacific Geotechnical Engineers, 2009. “F-22 Lo/Composite Repair Facility.”

Sherrod, D.R., Sinton, J.M., Watkins, S.E., and Brunt, K.M., 2007. “Geologic Map of the State of Hawaii: U.S. Geological Survey Open-File Report 2007-1089”. U.S. Department of the Interior, U.S. Geological Survey.

Shigemura, Lau, Sakanashi, Higuchi and Associates, 1994. “Fuel System Maintenance/Corrosion Control Facility.” Departments of the Army and Air Force National Guard of Hawaii.

Stearns, H.T. and K.N. Vaksvik, 1935. "Geology and Groundwater Resources of the Island of Oahu, Hawaii", Division of Hydrography, Bulletin 1.

U.S.G.S. Topographic Map, Pearl Harbor Quadrangles, 2017. United States Geologic Services.

FIGURES

Pearl Harbor, Oahu, Hawaii Project No. 21015

PROJECT LOCATION MAP

Location Map

Hawaiian Islands

FIGURE 1

APPROXIMATE

PROJECT

LOCATION

N

REFERENCE:

U.S.G.S. Topographic Map, Pearl Harbor Quadrangle, HI, 2017

0 2000 4000 FEET

APPROXIMATE SCALE: 1 INCH = 2000 FEET

M

AM

AL

A

BA

Y

DR

MA

MA

LA

B

AY

D

R

SEAMAN AVE

F-22 Plus-Up: Corrosion Control B3407 Pearl Harbor, Oahu, Hawaii Project No. 21015

AERIAL PHOTOGRAPH OF PROJECT LOCATION

Location Map

Hawaiian Islands

FIGURE 2

APPROXIMATE

PROJECT

LOCATION

N

REFERENCE:

Google Earth Imagery, 2015.

0 100 200 FEET

APPROXIMATE SCALE: 1 INCH = 100 FEET

Qcrs

DANIEL K. INOUYE

INTERNATIONAL

AIRPORT

Qot Qot

Qcrs

Qcrs

Qcrs

Qcrs Qot

Qf

Qbd Qbd

Qbd

PEARL

HARBOR

REEF RUNWAY

MAMALA BAY GOLF

COURSE

SE

AM

AN

A

VE

HICKAM

BEACH

FORT KAM RD

H I C K A M A I R

F O R C E B A S E

P E A R L H A R B O R

N A V A L S H I P Y A R D

SIG

NER

BL

VD

FOX BLVD

O'

MA

LL

EY

B

LV

D KUNTZ AVE

WORCHESTER AVEMA

MA

LA

B

AY

D

R

SEAMAN AVE

F-22 Plus-Up: Corrosion Control B3407 Pearl Harbor, Oahu, Hawaii Project No. 21015

REGIONAL GEOLOGY MAP

Location Map

Hawaiian Islands

FIGURE 3

APPROXIMATE

PROJECT

LOCATION

N

0 2000 4000 FEET

APPROXIMATE SCALE: 1 INCH = 2000 FEET

REFERENCE:

1. Sherrod, D.R., Sinton, J.M., Watkins, S.E., & Brunt, K.M., 2007, Geologic Map of the State of Hawaii: U.S. Geological Survey Open-File Report 2007-1089.

2. Google Earth Imagery, 2019.

LEGEND:

Fill (Holocene)Qf

Beach deposits (Holocene)Qbd Calcareous reef rock and marine sediment (Pleistocene)Qcrs

Qot Honolulu Volcanics (Pleistocene), Tuff cone deposits

B-1 C-1

C-2

APPROXIMATE FIELD EXPLORATION LOCATION PLAN

N

FIGURE 4

REFERENCE:

1. Google Earth Imagery, 2013 0 20 40 FEET

APPROXIMATE SCALE: 1 INCH = 20 FEET

LEGEND:

APPROXIMATE BORING LOCATION

APPROXIMATE PROBE / DYNAMIC CONE

PENETRATION (DCP) LOCATION

Pearl Harbor, Oahu, Hawaii Project No. 21015

APPENDIX A

Field Exploration

APPENDIX A. FIELD EXPLORATION

FINAL SUBMITTAL A-1

F-22 Plus-Up: Corrosion Control B3407

© 2024 Yogi Kwong Engineers, LLC

This appendix summarizes the results of the preliminary field exploration performed by YKE in support of the Hawaii Air National Guard F-22 Plus-Up: Corrosion Control B3407 project. Refer to Section 3.3 of this report for further discussion of encountered subsurface conditions. The approximate locations of the exploratory borings and probes/dynamic cone penetration tests (DCP) performed for this project are shown in Figure 4.

A.1 EXPLORATORY BORING AND PROBES

The field exploration included drilling one (1) exploratory borings, Boring B-1, and two (2) probes, Probes C-1 and C-2, to measure the thickness of the hanger pavement and perform DCP tests.

The Log of Boring B-1 is presented in Figure A-4. The boring was performed between January 25, 2022 and January 28, 2022, and drilled to an approximate depth of 103 feet below the existing ground surface. The boring was drilled by YK Drilling, LLC (YKD) using a Simco 2800 truck-mounted drill rig. Drilling was performed using 4-inch diameter solid stem augers and PQ-sized wash boring drilling methods, under the supervision of YKE. The drilling methods used are noted on the Log of Boring. After drilling, the boring was backfilled with tremie grout and Quikrete concrete.

The Log of Probes C-1 and C-2 are presented in Figures A-5 and A-6. The probes were performed on January 25, 2022 and explored to an approximate depth of 2.4 to 3.0 feet below existing ground surface. The probes were performed by YK Drilling, LLC using a CARDI core drill with a 4-inch diameter core barrel to core through the hangar floor pavement. After removing the pavement core, a hand auger was then used in soil sampling and a digging bar was used if the hand auger was having difficulties in advancing the probe holes. The drilling method used is noted on the Logs of Probes. The probes were backfilled with fast setting Quikrete to existing ground surface.

The backfill materials used are noted on the Logs of Probes.

A.2 SOIL SAMPLING AND ROCK CORING

Geotechnical soil sampling and coring were conducted under the supervision of YKE, who logged the materials encountered in each boring, and obtained soil samples and rock cores for further examination and laboratory testing.

Disturbed soil samples were obtained using a Standard Penetration Test (SPT) sampler (outside diameter (OD) of 2.0-inch and inside diameter (ID) of 1.5-inch). Relatively less disturbed soil samples were obtained using a Modified California Drive sampler (OD of 3-inch and ID of 2.5-inch. The samplers were driven into the ground by successive blows of a 140-pound hammer falling 30 inches. The samplers were typically driven for a total distance of 18 inches, and blow counts for each 6 inches of penetration were recorded. Where the SPT sampler was used, this procedure followed the ASTM D1586 standard for determining the standard penetration resistance

APPENDIX A. FIELD EXPLORATION

FINAL SUBMITTAL A-2

F-22 Plus-Up: Corrosion Control B3407

© 2024 Yogi Kwong Engineers, LLC of soil. Where the Modified California Drive was used, this procedure followed the ASTM D3550 standard practice for thick wall, ring lined, split barrel, drive sampling of soils. Blow counts for the last 12 inches of penetration are noted on the Logs of Borings at the respective sample depths.

For the probes, disturbed bag samples were obtained with a hand auger.

Soil samples recovered from the field were initially classified according to the ASTM D2488 standard and the Unified Soil Classification System, shown in Figure A-1. These classifications were later refined according to ASTM D2487 based on the results of laboratory tests performed on selected samples. Results of these tests are presented on the Log of Borings and Probes at the appropriate sample depths, and in Appendix B as appropriate.

Core samples were obtained using the PQ (approximately 3.25-inch diameter cores) wireline coring system in maximum 5-foot lengths.