Attachment 8 - 2021-09-23_RSLFAC Phase 2A_Revised Final Geotech Report_Al Qassim.pdf

FINAL COMBINED

GEOTECHNICAL

INVESTIGATION REPORT

SUBMITTED TO:

USACE Middle East District 201 Prince Frederick Drive Winchester, VA 22602

PREPARED BY:

Tetra Tech 100 Nickerson Road Marlborough, MA 01752

CONTRACT: W912QR-19-D-0029

TASK NUMBER: W912ER21F0004

21 September 2021 Corrected Final Submittal

Architect and Engineering Services for Royal Saudi Land Forces Aviation Command

Master Planning and Construction Phase 2A Facilities and Infrastructure

DAMMAM AIR BASE, TABUK AIR BASE, AL KHARJ LOGISTICS BASE,

KHAMIS MUSHAIT AIR BASE, AND AL QASSIM AVIATION INSTITUTE,

KINGDOM OF SAUDI ARABIA

Country Sensitive

CONTENTS

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1 INTRODUCTION 1

1.1 Background 1

1.2 Scope of Work 1

2 REPORTING 2

3 REFERENCES 4

Tables

Table 1-1 Field Investigation Dates Table 2-1 DRAFT Reporting Dates Table 2-1 FINAL Reports Appended to this Report

Appendices

Appendix 1: RSLFAC Phase 2A, Geotechnical Investigation Report, RSLF-AC 4th Aviation Group, Ad Dammam

Appendix 2: RSLFAC Phase 2A, Geotechnical Investigation Report, RSLF-AC Logistics Base, Al Kharj

Appendix 3: RSLFAC Phase 2A, Geotechnical Investigation Report, RSLF-AC 3rd Aviation Group, Tabuk

Appendix 4: RSLFAC Phase 2A, Geotechnical Investigation Report, RSLF Aviation Institute, Al Qassim

Appendix 5: RSLFAC Phase 2A, Geotechnical Investigation Report, RSLF-AC 2nd Aviation Group, Khamis Mushait

Collated Geotechnical Investigation Reports

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1 INTRODUCTION

1.1 Background

The Kingdom of Saudi Arabia (KSA), on behalf of the Royal Saudi Land Forces Aviation Command (RSLF-AC) and the US Government-implemented Foreign Military Sales (FMS) Cases SR-B-WAL is to provide for the purchase, deployment, and support of various rotary wing aircraft. The project includes design and construction services to establish, renovate, and augment RSLF-AC bases throughout the Kingdom to support the fielding and operations for these aircraft.

To facilitate this work Master Plans for five Rotary Wing Air Bases were prepared. The Master Plans were prepared for bases at Khamis Mushait (2nd Aviation Group), Tabuk (3rd Aviation Group), Dammam (4th Aviation Group), Al Qassim (Aviation Institute) and Al Kharj (Logistics Group).

Under W912ER-14-D-0004 Task Order 0006 the 65 % designs for the facilities and infrastructure were also prepared for the same bases. This current task order required TetraTech to update the previously prepared Master Plans prepared under W912ER-14-D-0004 Task Order 0004, prepare a new Master Plan for a new Rotary Wing Base, perform a geotechnical investigation at the five bases covered by W912ER-14-D-0004 Task Order 0006 and develop the 100 % facility and infrastructure design for three of the five bases covered by W912ER-14-D-0004 Task Order 0006.

1.2 Scope of Work

Tetra Tech GLS was contracted to undertake a Geotechnical Investigation Report (ref: 1). The following specific information was requested to be in this report, but was not limited to:

• Existing geotechnical (e.g., surface and subsurface) conditions

• Location of subsurface explorations, field tests, and samples

• Exploration logs

• Laboratory data, graphs, and results

• Geological setting

• Hydrological information

• Foundation recommendations (type of foundation system, minimum depth, bearing capacity, settlement analysis, and soil parameters). If deep foundations are recommended, include:

o pile capacity versus depth, o lateral pile load-deflection, o settlement calculations, o soil parameters

• Slab on grade other than pavements

• Liquefaction potential

• Seismicity

• Chemical analyses and discussion of corrosion potential

• Organic content

• Gypsiferous content

• Site development recommendations

• Ground water levels

• Pavement design criteria (CBR and k values)

• Recommendations for flexible and rigid pavements

• Compaction requirements

• Collapsible potential

• Settlement / heave discussion from the swell / collapse strains result

• Drainage and / or excavation problems, excavation recommendations

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• Lateral earth pressure coefficients (K0, Ka, Kp)

• Construction material recommendations (e.g. concrete, cement, asphalt, and aggregates)

• Field resistivity data and evaluation

The table below sets out the five bases in the order they were investigated.

Table 1-1 Field Investigation Dates

TT

Designation

RSLF-AC SITE Ground Investigation Date Range

1607 4th Aviation Group, Ad Dammam 13th December 2020 to 29th December 2020

1606 Logistics Base, Al Kharj 4th January 2021 to 13th January 2021

1605 3rd Aviation Group, Tabuk 25th January 2021 to 6th February 2021

1604 Aviation Institute, Al Qassim 10th February 2021 to 11th February 2021

1603 2nd Aviation Group, Khamis Mushait 23rd February 2021 to 6th March 2021

Tetra Tech GLS maintained a site presence during all the investigative works apart from at Khamis Mushait which was not attended at the client's request.

2 REPORTING

Prior to the publication of this report, draft versions were issued for USACE comment, dated as indicated on Table 2-1 below. Included within each of these reports were draft versions of the factual report as well as any other factual data previously made available by the client.

Table 2-1 DRAFT Reporting Dates

RSLF-AC SITE Initial Issue for USACE comment

4th Aviation Group, Ad Dammam 19th February 2021

Logistics Base, Al Kharj 12th March 2021

3rd Aviation Group, Tabuk 9th April 2021

Aviation Institute, Al Qassim 16th April 2021

2nd Aviation Group, Khamis Mushait 30th April 2021

The US ACE provided comments back typically within 2 weeks of receiving the draft report. USACE comments have been addressed and reports updated with additional data received from the ground investigation contractor since the issue of the draft reports.

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A final version of each of the five (5) reports above is now included in the appendix to this report as indicated in the table below:

Table 2-2 FINAL Reports Appended to this Report

RSLF-AC SITE Appendix

4th Aviation Group, Ad Dammam 1

Logistics Base, Al Kharj 2

3rd Aviation Group, Tabuk 3

Aviation Institute, Al Qassim 4

2nd Aviation Group, Khamis Mushait 5

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3 REFERENCES

1. 4th March 2020, United States Army Corps of Engineers Middle East District, Scope of Work, Architect and Engineering Services for Royal Saudi Land Forces Aviation Command Master Planning and Construction Phase 2A Facilities And Infrastructure, Contract #W912QR- 19-D-0029; Task Order # W912ER20FXXXX

Appendix 4 RSLFAC Phase 2A, Geotechnical Investigation Report, RSLF Aviation Institute, Al Qassim

U.S. Army Corps of Engineers

RSLF-AC Phase 2A Final Geotechnical Investigation Report

RSLF Aviation Institute, Al Qassim, Kingdom of Saudi Arabia

Task Order: W912ER21F0004

7th July 2021

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0 EXECUTIVE SUMMARY 1

1 INTRODUCTION 4

1.1 Background 4

1.2 Scope of Work 4

1.3 Previous Reports 5

1.4 Clarification of UK / US Terminology 5

2 THE SITE 6

2.1 Introduction 6

2.2 Site Description and Topographical Setting 6

2.3 Buried Services 7

3 DESK STUDY 8

3.1 Site History 8

3.2 Geology 8

4 PREVIOUS INVESTIGATIONS 9

4.1 Background 9

4.2 2019 Arab Company for Laboratories and Soils (ACES) 9

4.2.1 Fieldwork 9

4.2.2 Field Testing 9

4.2.3 Laboratory Testing 10

4.2.4 Ground Conditions / Laboratory Test Results 11

4.2.5 Interpretation 12

5 2021 FIELDWORK AND LABORATORY TESTING 13

5.1 Fieldwork 13

5.2 Laboratory testing 14

6 GROUND CONDITIONS 16

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6.1 Summary of Findings 16

6.2 Made Ground 16

6.2.1 Extent of Material 16

6.2.2 Material Classification 16

6.2.3 Calcium Carbonate Testing Made Ground 17

6.3 Quaternary Deposits (Aeolian Sand) 18

6.3.1 Extent of Material 18

6.3.2 Material Classification 18

6.3.3 Calcium Carbonate Testing Quaternary Deposits (Aeolian Sand) 18

6.4 Sarah Formation 18

6.4.1 Extent of Material 18

6.4.2 Material Classification 19

6.5 Groundwater 20

6.6 pH, Sulphate, Chloride and Gypsum Testing 20

6.7 Soil Resistivity Testing 21

7 GROUND MODEL / MATERIAL PROPERTIES 22

8 SEISMIC CONSIDERATIONS 23

8.1 Risk Category of Buildings for Seismic Design 23

8.2 Seismic Data 23

8.3 Preliminary Identification of Site Class for Seismic Design 24

8.4 Liquefaction Potential 25

9 ENGINEERING RECOMMENDATIONS 26

9.1 Proposed Development 26

9.2 Foundation Design 26

9.2.1 General 26

9.2.2 Bearing Capacity 27

9.3 Concrete for Foundations 28

9.4 Pavement Design Criteria 28

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9.5 Cathodic Protection 29

9.6 Earth Pressure Coefficients 30

9.7 Collapse and Swelling Considerations 30

10 GEOTECHNICAL RISK REGISTER 32

11 FURTHER WORK 33

12 REFERENCES 34

Tables

Table 1-1 US / UK Civil Engineering Terminology Table 4-1 ACES Soaked CBR Results Table 5-1 Number of Laboratory Tests Undertaken (Qassim) Table 6-1 Summary of In-situ CBR Test Results in Made Ground Table 6-2 Summary of Field Density Test Result in Made Ground Table 6-3 Summary of Laboratory Compaction Testing in Made Ground Table 6-4 RQD Ranges Table 6-5 Rock Quality Classification Table 6-6 Summary of “Chemical” Testing Table 6-7 Summary of Soil Resistivity Test Results Table 7-1 Ground Model Table 7-2 Summary of Material Properties Table 8-1 Risk Category of Buildings and Other Structures Expected on Site Table 8-2 Assumed Seismic Data for Al Qassim Base Table 9-1 Summary of Proposed Development Table 9-2 Square Pad Foundation Sizing Table 9-3 Trench Foundation Sizing Table 9-4 Relationship Between Soil Resistivity and Corrosion Rate of Isolated Buried Structures

(USACE)

Table 9-5 Lateral earth pressure coefficients for the Quaternary Deposits (Aeolian Sand)

Figures

Figure 1: Al Qassim (1604) Site Location Plan Figure 2: Al Qassim (1604) Site Plan

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Figure 3: Al Qassim (1604) Site Geology Plan Figure 4: Al Qassim (1604) Exploratory Hole Location Plan Figure 5: Al Qassim (1604) Proposed Development Figure 6: SPT “N” vs Depth - Al Qassim Figure 7: SPT “N” vs Elevation - Al Qassim Figure 8.1 to 8.3: Borehole Coring Data - Al Qassim Figure 9: Uniaxial Compressive Strength vs Depth - Al Qassim Figure 10: Point Load Index vs Depth - Al Qassim Figure 11: Natural Moisture Content vs Depth - Al Qassim Figure 12: All Particle Size Distribution - Al Qassim Figure 13: All Soil Resistivity Test Results - Al Qassim

Appendices

Appendix A: 2021 Osaimi Geotechnical Investigation Factual Report Appendix B: 2019 Arab Company for Laboratories and Soil (ACES) - Geotechnical Investigation Report Appendix C: Geotechnical Risk Register Appendix D: Foundation Calculations

Geotechnical Interpretative Report

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0 EXECUTIVE SUMMARY

This report covers the geotechnical investigation (fieldwork and laboratory testing) at the RSLF Aviation Institute, Al Qassim.

The base is located approximately 1 km to the west of Prince Nayef Bin Abdulaziz International Airport and approximately 20 km to the west of the city of Buraydah within the Al Qassim Region of Saudi Arabia.

The project site is a rectangular plot of land partly comprising a fenced-off, disused, asphalt-covered car park, a rough surfaced area comprising orange-brown sand, a section of asphalt-covered road and car park (with sunshade) and grass covered landscaped areas.

A flooded / blocked foul drainage pipe is present on the site beneath the proposed building location.

Based on the depth of the manholes, the pipework appeared to fall towards the northwest.

According to the 1:250,000 Geologic Map of the Buraydah Quadrangle, the base is underlain by Quaternary age superficial deposits. The map shows the base to be situated on an Inactive Sheet Gravel layer. The site sits on the westernmost point of these deposits close to a boundary with a Calcareous Duricrust. These two (2) layers of Quaternary age superficial deposits are bounded to the north by an active sheet sand referred to as “Eolian” Sand. Beneath the superficial deposits, the Sarah Formation is present.

The fieldwork programme comprised the following:

• 3 rotary boreholes using rock roller open holing and double barrel coring with bentonite mud flush to a depth of 10.0 m (see Figures 8.1 to 8.3)

• 2 machine-excavated trial pits to a depth of 3.0 m

• In-situ geotechnical testing, comprising:

o standard penetration testing in the boreholes o 1 field measurement of soil resistivity o 1 field density test o 2 field measurements of California Bearing Ratio (CBR)

• Small disturbed and bulk disturbed sampling from trial pits and small disturbed sampling and rock coring (where possible) in boreholes.

The investigation encountered a limited thickness of made ground overlying natural soils of the Quaternary Deposits (Aeolian Sand) between 2.5 m and 3.6 m thick. These were found to overlie the Sarah Formation, which was proved to the full depth investigated, 10 m. The Inactive Sheet Gravel and Calcareous Duricrust were not encountered.

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The following design parameters are recommended.

Layer Stratum Unit density (kN/m3) ϕ’ (°) [c’ (kPa)]

Compressive Strength

(MPa)

Undrained Shear

Strength, cu (kPa)

Elastic Modulus, Esi

(MPa)

1 Made Ground 20 30 / [0] - - -

2 Quaternary Deposits (Aeolian Sand) 16 30 / [0] - - 10

3 Sarah Formation 21 40 / [0] 10 - -

Detailed information on the expected foundation loads for the building and bridge (elevated concrete walkway) has not been provided. However, the proposed structures are expected to impose relatively low loads as they are limited to two-storeys in height. Shallow foundations are therefore expected to be suitable throughout. Piled foundations are not expected to be required.

It is understood that steel columns are to be supported by cast-in-place concrete square spread footings. The perimeter building walls are to be made of concrete masonry unit (CMU) walls supported by continuous strip footings. Interior CMU walls are to be supported on thickened areas of floor slab.

The proposed ground floor is a concrete slab-on-grade.

The presence of an existing foul sewer beneath the northeastern end of the building will affect the proposed foundations of the new building. The nearest manhole to the proposed building indicates that the sewer is located at a depth of at least 2.40 m below ground level. It is considered very likely that at this depth, the sewer would have been lain within a trench excavated from ground level, rather than bored. The quality of the backfill material to the trench will not be as good as the natural soils surrounding it, especially as these are likely to comprise normally consolidated windblown sands.

Depending upon the USACE and local KSA construction codes / rules, it may not be possible to construct a new building over an existing live sewer due to the potential damage that may occur to either the sewer during construction or both the sewer and building post-construction. It may be necessary to design the foundations to bridge over the sewer location. Alternatively, if drainage falls can be accommodated, consideration could be given to relocating the sewer around the proposed building.

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The net allowable bearing pressures given below should be applied to foundations only on the naturally occurring Quaternary Deposits (Aeolian Sand).

Foundation size Allowable qa (net) (kPa) qSLS (net) (kPa) qa (kPa)

Allowable foundation load NOTE 2

(kN)

0.75 m x 0.75 m 146 296 146 82

1 m x 1 m 156 240 156 156

1.5 m x 1.5 m 177 180 177 399

2 m x 2 m 198 148 148 590

2.5 m x 2.5 m 219 127 127 792

3 m x 3 m 241 112 112 1,010 NOTE 2 The values are for vertical loads only, applied centrally to the foundation. For foundations with eccentric loading, the effective bearing area should be calculated, and the allowable bearing capacity applied accordingly.

Foundation size Allowable qa (net) kPa qSLS (net) kPa qa kPa

Allowable foundation load NOTE 3

(kN/m)

0.75 m strip 154 177 154 115

1 m strip 167 145 145 145

1.5 m strip 193 110 110 165

2 m strip 219 91 91 182

2.5 m strip 246 79 79 198 NOTE 3 The values are for vertical loads only, applied centrally to the foundation. For foundations with eccentric loading, the effective bearing area should be calculated, and the allowable bearing capacity applied accordingly.

It is recommended that foundation concrete at the Al Qassim site is designed to the Arabian Peninsula Sulphate Class S-1.

A preliminary design CBR value of 15% is recommended for the site, together with a representative k-value of 2,039 kPa/mm (552.6 psi/in)

It would appear that most of the site is within a medium to high anticipated resistivity to corrosion classification area with mild to moderate expected activity.

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1 INTRODUCTION

1.1 Background

The Kingdom of Saudi Arabia (KSA), on behalf of the Royal Saudi Land Forces Aviation Command (RSLF-AC) and the US Government-implemented Foreign Military Sales (FMS) Cases SR-B-WAL is to provide for the purchase, deployment, and support of various rotary wing aircraft. The project includes design and construction services to establish, renovate, and augment RSLF-AC bases throughout the Kingdom to support the fielding and operations for these aircraft.

To facilitate this work Master Plans for five (5) Rotary Wing Air Bases were prepared. The Master Plans were prepared for the bases at Khamis Mushait (2nd Aviation Group), Tabuk (3rd Aviation Group), Dammam (4th Aviation Group), Al Qassim (Aviation Institute) and Al Kharj (Logistics Group). Under W912ER-14-D-0004 Task Order 0006 the 65% designs for the facilities and infrastructure were prepared for the same bases. This current task order required TetraTech to update the previously prepared Master Plans prepared under W912ER-14-D-0004 Task Order 0004, prepare a new Master Plan for a new Rotary Wing Base, perform a geotechnical investigation at the five (5) bases covered by W912ER-14-D-0004 Task Order 0006 and develop the 100% facility and infrastructure design for three

(3) of the five (5) bases covered by W912ER-14-D-0004 Task Order 0006.

This report covers the geotechnical investigation (fieldwork and laboratory testing) at the RSLF Aviation Institute, Al Qassim.

1.2 Scope of Work

Tetra Tech GLS was contracted to undertake a Geotechnical Investigation Report (ref: 1). The following specific information was requested to be in this report, but was not limited to:

• Existing geotechnical (e.g. surface and subsurface) conditions

• Location of subsurface explorations, field tests, and samples

• Exploration logs

• Laboratory data, graphs, and results

• Geological setting

• Hydrological information

• Foundation recommendations (type of foundation system, minimum depth, bearing capacity, settlement analysis, and soil parameters). If deep foundations are recommended, include:

o pile capacity versus depth, o lateral pile load-deflection, o settlement calculations, o soil parameters

• Slab on grade other than pavements

• Liquefaction potential

• Seismicity

• Chemical analyses and discussion of corrosion potential

• Organic content

• Gypsiferous content

• Site development recommendations

• Ground water levels

• Pavement design criteria (CBR and k values)

• Recommendations for flexible and rigid pavements

• Compaction requirements

• Collapsible potential

• Settlement / heave discussion from the swell / collapse strains result

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• Drainage and / or excavation problems, excavation recommendations

• Lateral earth pressure coefficients (K0, Ka, Kp)

• Construction material recommendations (e.g., concrete, cement, asphalt, and aggregates)

• Field resistivity data and evaluation

The scope changed since the instigation of the originally proposed investigation and hence some areas were not investigated.

1.3 Previous Reports

The following report was provided to assist in the preparation of this report:

28th January 2019, Arab Company for Laboratories and Soil (ACES), Geotechnical Site Investigation for RSLFAC Phase 2A Base Expansion, The Aviation Institute Simulator Building, Qassim Project, Qassim, K.S.A., Report No.: S18000138, Revision No. 0, Description: Final Interpretive Report (Appendix B, ref: 3)

The 2021 investigation (this report) was designed to complement, rather than duplicate, the work undertaken in 2019 and the data contained in the earlier report has been combined with the recent investigation data to provide a clearer picture of the ground conditions.

1.4 Clarification of UK / US Terminology

Throughout the fieldwork period a small amount of confusion arose due to the difference between the US English civil engineering terminology vs. the British English civil engineering terminology. This report has been written by British English-speaking engineers using British civil engineering terminology. The following table clarifies some of the issues that were noted during the fieldwork and should not be viewed as exhaustive.

Table 1-1 US / UK Civil Engineering Terminology

US Term UK Term parking lot car park fill made ground (in UK practice placed engineered material would be described as “fill”) sanitary sewer foul sewer / drain storm drain surface water sewer / drain utility vault manhole curb kerb sidewalk footpath / pavement armor armour

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2 THE SITE

2.1 Introduction

The Al Qassim Base is currently occupied by the Aviation Institute of the Royal Saudi Land Forces - Aviation Command (RSLF-AC) and is located approximately 1 km to the west of Prince Nayef Bin Abdulaziz International Airport and approximately 20 km to the west of the city of Buraydah within the Al Qassim Region of Saudi Arabia. Figure 1 shows the approximate site location within the country of The Kingdom of Saudi Arabia (KSA). All figures are presented between the main text of, and appendices to, this report.

The RSLF-AC Aviation Institute base is a roughly 2.5 km by 0.8 km trapezoidal shaped site. The main entrance gate to the base is located on the northeastern side approximately 1 km northwest from the entrance to the airport.

The project site is located inside the base on the southwestern boundary, adjacent to the boundary wall.

The site is roughly 700 m due west of the base main entrance gate.

The project site is bounded to the southwest by the base boundary wall, beyond which is an open patch of land, then a footpath and then an unnamed three (3) lane road. To the northeast the project site is bounded by an unnamed internal base road. To the southeast the base is bounded by a car park and access road, two-storey office / training building and a patch of vacant land. To the northwest the project site is bounded by a car park and access road, single storey building and patch of vacant land.

Figure 2 shows a layout plan of the project site at the time of investigation (January 2021).

2.2 Site Description and Topographical Setting

A site walkover was undertaken by Coffey during the ground investigation works in February 2021. As part of their contract, the ground investigation contractor also undertook a topographical survey of the project site coincidental with the ground investigation works and this is referred to in this report as the 2021 topographical survey.

All levels discussed below relate to the 2021 topographical survey (ref: 5) and a site datum (SD).

Please see Section 5.1 for further explanation.

The project site is a rectangular plot of land measuring approximately 100 m northwest to southeast by 75 m northeast to southwest. It is set between an existing two-storey office / training building to the southeast and the single storey “Learning Centre Building” to the northwest.

The site mostly comprises an area of ground surrounded by a 2 m high chain-link fence located centrally and to the southwest of the centre of the site. The area inside the fence measures approximately 80 m northwest to southeast by 55 m northeast to southwest and is set at a level of approximately +650 mSD.

The northwestern half of the area inside the fence comprises a disused, asphalt-covered car park, whilst the southeastern half predominantly comprises rough surfaced ground consisting of an orange-brown sand. Three (3) small open excavations with no guard barriers were present, each measuring roughly 5 m by 2 m and up to 1 m deep at the deepest point. It is thought that these may have been previous excavations for services or foundations for an earlier project.

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Some minor landscaped areas are present along the southeastern, part of the southwestern and part of the northwestern boundaries of the fenced off area. Semi-mature trees are located within these areas.

Outside the 2 m high chain-link fence, to the northwest and northeast is a patch of asphalt-covered road.

To the northwest of this road is a grass covered landscaped area which slopes up very gently to a further asphalt car park and access road adjacent to the “Learning Centre Building”, set at a level of +650.25 mSD. A 0.5 m high grass covered landscaped mound is located at the northeastern end of this gently sloping area.

To the northeast of the fenced area, and beyond the road, is an area occupied by a car park sunshade.

Beyond the car park sunshade is a small grass-covered ditch roughly 0.25 m deep. This ditch contained no water during the site visit. Trees were spaced at 5 m intervals along the length of the ditch. Beyond the ditch is an asphalt covered base access road. This road crosses the ditch close to the eastern corner of the site via a small bridge and culvert.

2.3 Buried Services

As part of this investigation, the contractor also undertook a topographical survey of the site which included locating all visible buried services. A basic review of the buried and above ground services that cross and immediately surround the site has been carried out and is described below:

Drainage

No surface water drainage manhole covers were visible on or immediately surrounding the site. Excess water that collects on the impermeable surfaces during periods of rain is allowed to drain through gaps in the kerb stones, where present, or flows directly into the plant beds at the sides of the roads / car parks or into the drainage ditch present along the northeastern boundary.

Foul drainage is present on the site beneath the asphalt road within the northeastern boundary. All of the manhole covers lifted found the inspection chamber to be flooded, suggesting that there was a blockage further down the system. Based on the depth of the manholes, the direction of flow appeared to be towards the northwest.

Electric and Communications

Electric lighting is present along the base access road and within the car park sunshades. The supply cables to these were not surveyed. No other obvious electric cables were noted.

Water

Black plastic water irrigation pipework is present within all the landscaped areas. This has not been surveyed.

A drinking water supply pipe is present adjacent to the northeastern side of the 2 m high chain-link fence. This appears to be the supply to the two-storey office / training building to the southeast and the single storey “Learning Centre Building”.

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3 DESK STUDY

3.1 Site History

A brief and simple desk study was undertaken in order to put the ground investigation into context.

The history of the project site at the base has been researched using Google Earth historical satellite imagery only. All dates mentioned are those indicated by Google Earth.

Reference to Google Earth historical satellite imagery indicates that the site area was already in use as an asphalt car park in 2004. It is likely that this car park was constructed at the same time as the two-storey office / training building to the southeast and single storey building to the northwest. The asphalt area was divided into sections separated by a northwest to southeast orientated row of vegetation. A car park sunshade was erected on the northeastern side of the asphalt adjacent to the interior base road in mid-2018.

In early 2019, the entire site was fenced off excluding a section of asphalt on the northwestern and northeastern edge of the site (adjacent to the car park sunshade) which allowed for access to a contractor compound located further to the northwest. Around the same time, the asphalt on the southeastern half of the site was stripped. No further changes have occurred on site since 2019.

3.2 Geology

According to the 1:250,000 Geologic Map of the Buraydah Quadrangle (ref: 4), the base is underlain by Quaternary age superficial deposits. An extract of the 1:250,000 Geologic Map of the Buraydah Quadrangle is presented in Figure 3. The map shows the base to be situated on an Inactive Sheet Gravel (Qgx) layer consisting of boulders, pebbles, gravels and sands. The site boundary sits on the westernmost point of these deposits close to a boundary with a Calcareous Duricrust (Qdcx). These two (2) layers of Quaternary deposits are bounded to the north by an active sheet sand referred to as “Eolian” Sand (Qsz).

The bedrock layer which surrounds the Quaternary deposits on the east and west is called the Sarah Formation (SOs) of Early Silurian age which is described by the Saudi Geological Survey as a white, beige, or reddish, coarse to fine-grained sandstone with tillite locally at the base. No other rock outcrops are shown on the map close to the site.

The Structural Sketch Map included with the geology map goes on to indicate that no faults exist within the site vicinity, the nearest indicated being about 8 km to the north.

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4 PREVIOUS INVESTIGATIONS

4.1 Background

Coffey has been provided with an earlier geotechnical investigation report as follows:

28th January 2019, Arab Company for Laboratories and Soil, Geotechnical Site Investigation for RSLFAC Phase 2A Base Expansion, The Aviation Institute Simulator Building, Qassim Project, Qassim, K.S.A., Report No.: S18000138, Revision No. 0, Description: Final Interpretive Report (ref: 3)

A brief review of the fieldwork and laboratory testing carried out has been undertaken as part of this report and is discussed below. A copy of the report is included as Appendix B to this report.

4.2 2019 Arab Company for Laboratories and Soils (ACES)

This investigation was carried out for EG & G Middle East by ACES to assist with the design and construction of a simulator building on the RSLF Aviation Institute at Al Qassim. The fieldwork was carried out and completed in 3 days in January 2019. As part of the investigation works ACES also installed three (3) topographic surveying benchmarks across the site.

The purpose of the investigation was to determine the ground conditions of the site, undertake geotechnical laboratory testing and to provide sufficient information to enable foundation design.

4.2.1 Fieldwork

Six (6) boreholes were drilled to depths of between 4.0 m and 10.0 m initially using a down-the-hole hammer percussion with rotary air flush drilling technique down to the bedrock. Coring was then undertaken from the rockhead, but no information is provided in the ACES report as to the type of coring used (single, double or triple barrel) or what flush was used. Rock cores were recovered from the boreholes for laboratory testing.

Three (3) trial pits were also excavated in the same area using a mechanical excavator down to a depth of 3.0 m.

The locations of the exploratory holes from this investigation are indicated on Figure 4 to this report.

4.2.2 Field Testing

At least one (1) standard penetration test (SPT) was undertaken in each borehole in accordance with ASTM D 1586-08a, mostly at 1.50 m depth, although two (2) of the boreholes incorrectly state that the test was undertaken over a 1 m distance. Disturbed soil samples were recovered from the split spoon sampler. The borehole records also suggest that composite samples were collected between the SPT testing. These would have been collected at the surface of the hole and well mixed together by the down-the-hole hammer drilling technique with air flush.

The trial pit records suggest that composite samples were taken from the trial pits between ground level and the full depth of investigation. It has been assumed that these were bulk samples of soil taken from throughout the full depth of the trial pit rather than at a specific depth. The composite sample would have included a mixture of all the strata encountered within that depth.

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Five (5) electrical resistivity tests were also carried out, reportedly in accordance with ASTM G 57-06 at spacings of 2 m, 4 m, 6 m and 8 m. There is no drawing of where these test were undertaken, nor indication of the orientation of these tests.

4.2.3 Laboratory Testing

4.2.3.1 General

Laboratory tests were carried out on the recovered samples from the boreholes and trial pits. The “composite” samples taken during trial pitting were considered suitable for a range of geotechnical testing. Results are quoted for a specific depth for trial pit samples, but as indicated above the logs suggest that composite samples were taken. For the boreholes, tests were undertaken on SPT samples or rock cores.

4.2.3.2 Particle Size Distribution (PSD) Tests

Particle size analyses were conducted on six (6) samples of natural soils recovered from the boreholes at depths of between 0.50 m and 1.0 m depth and the three (3) composite trial pit samples. It is not clear from the report text whether dry or wet sieving was used. The particle size distribution testing was undertaken in accordance with the Standard Test Method for Particle-Size Analysis of Soils, ASTM D 422-63 (2007). Particle size distribution was used for material classification according to the Unified Soil Classification System (USCS) as well as AASHTO soil classification for subgrade rating. Results were presented in the appendix of the report.

4.2.3.3 Moisture Content Tests

Moisture content testing was undertaken on a total of twelve (12) samples, nine (9) from the boreholes of which three (3) were from rock cores and three (3) from the composite trial pit samples. The tests were carried out in accordance with the Standard Test Method for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass, ASTM D 2216-10. Results were presented in a summary table in the text of the report only.

4.2.3.4 Plasticity Index Tests

Atterberg limit testing was carried out on nine (9) shallow samples to determine their plasticity characteristics. Testing was carried out on one (1) sample per borehole at either 0.5 m or 1.0 m depth and on the composite trial pit sample from each pit. Atterberg limit testing was undertaken in accordance with the Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soil, ASTM D 4318-10e1. Results were presented in a summary table in the text of the report and in the appendices.

4.2.3.5 Compaction (Proctor) Tests

A compaction (Proctor) test was carried out on one (1) of the composite bulk trial pit samples (TP-01) to determine Maximum Dry Density (MDD) and Optimum Moisture Content (OMC) values. The compaction tests were carried out using the Standard Test Method for Laboratory Compaction characteristics of Soil Using Modified Effort (56,000 -lbf/ft3) (2,700 kN-m/m3), ASTM D 1557-12.

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4.2.3.6 California Bearing Ratio (CBR) Tests

ACES state that one (1) soaked California Bearing Ratio (CBR) test was also carried out on the TP-01 composite bulk trial pit sample, but no indication of the length of time the sample was soaked for is reported. The soaked CBR test was carried out to the Standard Test Method for CBR (California Bearing Ratio) of Laboratory-Compacted Soils, ASTM D 1883-07.

4.2.3.7 Uniaxial Compressive Strength of Intact Rock Core Samples

A total of three (3) UCS tests were carried out on core samples of sandstone recovered from the boreholes at depths ranging from 3.0 m to 6.5 m. The UCS tests were carried out in accordance with the Standard Test Methods for Compressive Strength and Elastic Moduli of Intact Rock Core Specimens under Varying States of Stress and Temperatures, ASTM D 7012-14.

4.2.3.8 Chemical Analyses

One (1) shallow soil sample was tested for pH, acid soluble sulphate (as SO3 % and SO4 %) and acid soluble chloride (as Cl %) to British Standard BS 1377:1990, Part 3. Two (2) groundwater samples from the boreholes were also tested for pH, sulphate content (as SO3 g/l), chloride content (as Cl g/l) and total dissolved solids (TDS as g/l).

4.2.4 Ground Conditions / Laboratory Test Results

The boreholes all encountered made ground to depths of between 0.3 m and 0.4 m composed of asphalt and silty sand with gravels. The trial pits also encountered made ground to a depth of 0.4 m described as brown, silty sand with gravels.

Beneath the made ground, superficial deposits of medium dense, occasionally loose, reddish brown, poorly graded sand with silt were recorded in both the trial pits and boreholes to a depth of between

3.0 m and 3.5 m.

Beneath the superficial deposits, reddish brown, moderately to slightly fractured and moderately to slightly weathered, silty sandstone with thin beds of claystone or clayey siltstone was encountered to the full depth of investigation.

Within the 10 m deep boreholes, groundwater was encountered at depths of between 3.8 m to 4.1 m.

All the other exploratory locations were found to be dry to the full depth investigated.

Natural moisture contents for the soils ranged between 1.8 % and 3.9 %, whilst for the rock it was

0.11 % in all three (3) cores. There is no explanation as to why the three (3) samples of rock core from three (3) different boreholes all had exactly the same moisture content of 0.11 %. This included two (2) samples of core taken from below the water table.

The PSDs showed the composite borehole samples to be predominantly sand with between 5 % and 12 % gravel and 0.5 % to 8.3 % silt and clay. They were described as being either SP or SP-SM.

These samples collected would very likely have been affected by the drilling technique, in that any larger particles would have been pulverised into smaller particles by the action of the down-the-hole hammer, and these results may not be truly representative of the soils encountered. The composite trial pit samples were again predominantly sand with between 8 % and 11 % gravel and 7.6 % to 9.2 % silt and clay. They were all described as being SP-SM.

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All plasticity index test results revealed the shallow soils from the boreholes and trial pits to be non-plastic.

The three (3) UCS tests indicated the rock strength to vary between 18.9 MPa and 21.1 MPa.

Compaction testing indicated that the composite sample from Trial Pit TP-01 had a maximum dry density (MDD) of 1.80 g/cm3 and an optimum moisture content (OMC) of 6%.

The laboratory CBR value in the compacted composite sample from Trial Pit TP-01 was, at 95% compaction of the MDD, found to be 19 % whilst the CBR value at 98% compaction of the MDD was found to be 22 %. The table below shows the results of the soaked CBR tests (length of soaking unknown) on the composite sample from Trial Pit TP-01.

Table 4-1 ACES Soaked CBR Results

Result Compaction

10 blows 30 blows 65 blows

CBR (%) 9 20 40

% of MDD 92 97 107

% of OMC 131 126 128

The single composite soil sample from Borehole BH-01 at 1.0 m depth recorded a pH of 7.9, acid soluble sulphate (as SO4) of 0.2 % and acid soluble chloride (as Cl) of 0.04 %.

The two (2) water samples recorded pH of 6.9 to 7.2, sulphate content (as SO3) of 2.6 g/l to 3.5 g/l and chloride content (as Cl) of 2.85 g/l to 1.30 g/l.

4.2.5 Interpretation

A full interpretation of fieldwork and test results is provided. The investigative report presents recommendations for foundation depth and type, allowable bearing capacity, foundation settlement for shallow foundations on natural soils, bedrock and fill and provides modulus of subgrade reaction for isolated footings and raft foundations.

A full copy of the report is included as Appendix B to this report.

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5 2021 FIELDWORK AND LABORATORY TESTING

5.1 Fieldwork

The intrusive investigation was undertaken by Ayed Eid Al Osaimi Engineering Consulting Office (Osaimi). The investigation was designed to complement, rather than duplicate, the investigation undertaken in 2019, hence the locations of the boreholes should be viewed in conjunction with those for the 2019 investigation.

A copy of the Osaimi report is located within Appendix A. The scope of work undertaken is summarised in the following paragraphs.

Seismic testing, testing for the presence of explosive, radiological, biological and “chemical” contamination, and surveying for the presence of unexploded ordnance did not form part of the scope of this investigation.

Intrusive geotechnical exploratory holes and field testing broadly in accordance with the standards below have been undertaken as part of the investigation.

D 420-18 Standard Guide for Site Characterization for Engineering Design and Construction Purposes

D 2487-17e1 Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System)

D 2488-17e1 Standard Practice for Description and Identification of Soils (Visual-Manual Procedures)

D 2113-14 Standard Practice for Rock Core Drilling and Sampling of Rock for Site Exploration D 1586 / D 1586M-18 Standard Test Method for Standard Penetration Test (SPT) and Split-

Barrel Sampling of Soils D 4220 / D 4220M-14 Standard Practices for Preserving and Transporting Soil Samples D 4429-09a Standard Test Method for CBR (California Bearing Ratio) of Soils in Place

(Withdrawn 2018) D 1556 / D 1556M-15e1 Standard Test Method for Density and Unit Weight of Soil in Place by

Sand-Cone Method G 57-20 Standard Test Method for Measurement of Soil Resistivity Using the Wenner Four-

Electrode Method

Prior to work commencing, Osaimi deployed a topographical surveyor to set out the various exploratory hole locations. The exploratory holes undertaken as part of this investigation have all been surveyed using the benchmarks set up during the ACES investigation.

The exploratory work was undertaken by Osaimi between the 10th February 2021 and 11th February 2021. The investigation included intrusive works (hand-dug trial pits, rotary boreholes, machine-excavated trial pits) as well as measurements of soil electrical resistivity, field density and field CBR. The works comprised the following:

• 3 rotary boreholes using rock roller open holing and double barrel coring with bentonite mud flush to a depth of 10.0 m (see Figures 8.1 to 8.3)

• 2 machine-excavated trial pits to a depth of 3.0 m

• In-situ geotechnical testing, comprising:

o standard penetration testing in the boreholes o 1 field measurement of soil resistivity o 1 field density test o 2 field measurements of California Bearing Ratio (CBR)

• Small disturbed and bulk disturbed sampling from trial pits and small disturbed sampling and rock coring (where possible) in boreholes.

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An exploratory hole location plan is presented on Figure 4.

Prior to drilling the boreholes, a 1 m deep hand dug trial pit was excavated (except on areas of asphalt) to check that the location was clear of shallow services. All exploratory locations were also scanned using a utility line cable locator / cable avoidance tool (CAT).

5.2 Laboratory testing

Geotechnical laboratory testing in accordance with the standards below has been undertaken as part of the investigation. The results are included in the report included in Appendix A.

American Society for Testing and Materials (ASTM) standards:

• D 422-63 (2007)e2 Standard Test Method for Particle-Size Analysis of Soils (Withdrawn 2016)

• D 1140-17 Standard Test Methods for Determining the Amount of Material Finer than 75-μm

(No. 200) Sieve in Soils by Washing

• D 1557-12e1 Standard Test Methods for Laboratory Compaction Characteristics of Soil Using

Modified Effort (56,000 ft-lbf/ft3 (2,700 kN-m/m3))

• D 2216-19 Standard Test Methods for Laboratory Determination of Water (Moisture) Content of

Soil and Rock by Mass

• D 2488-17e1 Standard Practice for Description and Identification of Soils (Visual-Manual

Procedures) - Calcium Carbonate

• D 4318-17e1 Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils

• D 5333-03 Standard Test Method for Measurement of Collapse Potential of Soils (Withdrawn

2012)

• D 5731-16 Standard Test Method for Determination of the Point Load Strength Index of Rock and Application to Rock Strength Classifications

• D 7012-14e1 Standard Test Methods for Compressive Strength and Elastic Moduli of Intact

Rock Core Specimens under Varying States of Stress and Temperatures

• D 1883-16 Standard Test Method for California Bearing Ratio (CBR) of Laboratory-Compacted

Soils

American Association of State Highway and Transportation (AASHTO) standards:

• AASHTO T 290-95 Standard Method of Test for Determining Water-Soluble Sulfate Ion Content in Soil - Gypsum Content

British Standard Institution (BS) standards:

• BS 1377:1990 Incorporating Amendment No. 1 Methods of test for Soils for Civil Engineering Purposes - Part 3: Chemical and Electro-chemical Tests o Clause 5 Determination of the Sulphate Content of Soil o Clause 7 Determination of the Chloride Content o Clause 9 Determination of the pH Value

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Table 5-1 Number of Laboratory Tests Undertaken (Qassim)

Standard: Designation: Number of Tests:

Standard Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass D 2216-19 6

Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils D 4318-17e1 6

Standard Test Method for Particle-Size Analysis of Soils (Withdrawn 2016) D 422-63 (2007)e2 6

Standard Test Methods for Determining the Amount of Material Finer than 75-μm (No.

200) Sieve in Soils by Washing D 1140-17 6

Standard Practice for Description and Identification of Soils (Visual-Manual Procedures)

- Calcium Carbonate D 2488-17e1 6

Standard Test Method for Measurement of Collapse Potential of Soils (Withdrawn 2012) D 5333-03 2

Standard Test Method for Determination of the Point Load Strength Index of Rock and Application to Rock Strength Classifications D 5731-16 1

Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort (56,000 ft-lbf/ft3 (2,700 kN-m/m3)) D 1557-12e1 4

Standard Test Methods for Compressive Strength and Elastic Moduli of Intact Rock Core Specimens under Varying States of Stress and Temperatures D 7012-14e1 7

Standard Test Method for California Bearing Ratio (CBR) of Laboratory-Compacted Soils D 1883-16 4

Methods of test for Soils for civil engineering purposes - Part 3: Chemical and electro-chemical tests Clause 9 Determination of the pH value

BS 1377-3:1990

Incorporating Amendment No. 1

Methods of test for Soils for civil engineering purposes - Part 3: Chemical and electro-chemical tests Clause 5 Determination of the sulphate content of soil and ground water

Methods of test for Soils for civil engineering purposes - Part 3: Chemical and electro-chemical tests Clause 7 Determination of the chloride content

Standard Method of Test for Determining Water-Soluble Sulfate Ion Content in Soil - Gypsum Content

AASHTO T 290-95

(2016) 4

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6 GROUND CONDITIONS

6.1 Summary of Findings

The ground investigation appears to have broadly confirmed the expected ground conditions in that, beneath a limited thickness of made ground, natural Quaternary Deposits (Aeolian) Sand were encountered and found to overlie the Sarah Formation at depth.

However, the Quaternary Deposits (Aeolian) Sand encountered during the ground investigation were not the expected “Inactive Sheet Gravel” or “Calcareous Duricrust” but, based on Coffey site observations, the natural soils were considered to represent more accurately “Eolian (Aeolian) Sand”.

6.2 Made Ground

6.2.1 Extent of Material

Made ground was present in all areas of the site beneath the proposed building footprint.

Five (5) of the exploratory locations (BH01, BH02, CBR01, CBR02 and TP02) were undertaken in areas surfaced in asphalt. Visual inspection of the asphalt core from the boreholes showed a thickness of 60 mm. Slabs of asphalt broken out by the mechanical excavator also show the asphalt thickness to be 60 mm.

All three (3) boreholes indicated made ground to extend to a depth of 1.0 m below ground level, although Boreholes BH01 and BH02 were cored from ground level to 1 m and thereafter open holed, so the depth is only approximate in these holes. Within Borehole BH03, the made ground is described by the contractor as light brown, silty, gravelly, fine to medium sand.

Trial pit record descriptions from Trial Pits TP01 and TP02 show the made ground thickness to be between 0.5 m and 0.7 m. The CBR and FDT trial pits only extended to a maximum depth of 0.5 m and therefore did not penetrate the base of the made ground. Within Trial Pits TP01 and TP02 the made ground is described by the contractor as brown, poorly graded sand with silt, gravel and cobbles.

The made ground was described as “hand excavation, hard effort to excavate” in BH03. Most mechanically excavated exploratory locations were described as “moderately hard to excavate” (below the asphalt).

6.2.2 Material Classification

Due to its limited thickness, no SPT testing was undertaken within the made ground.

Four (4) moisture contents were measured on the made ground up to a depth of 0.7 m. These results range from 2.1% to 6.2% and are shown plotted against depth in Figure 11.

The particle size distribution…