NSW DEPARTMENT OF COMMERCE

PRELIMINARY GEOTECHNICAL INVESTIGATION

AREAS A AND C

LONG BAY CORRECTIONAL COMPLEX, MALABAR

E12723.3-AV

22 February 2005

E12723.3-AV 22 February 2005

8/12 Mars Road Lane Cove West NSW 2066 Australia

PO Box 125 North Ryde NSW 1670 Australia

Telephone +61 2 9911 1000 Facsimile +61 2 9911 1001

Email sydney@coffey.com.au

NSW Department of Commerce Level 13, McKell Building 2-24 Rawson Place SYDNEY NSW 2000 Attention: Mr Peter Shun Dear Sir, RE: PRELIMINARY GEOTECHNICAL INVESTIGATION

AREAS A AND C LONG BAY CORRECTIONAL COMPLEX, MALABAR

Coffey Geosciences Pty Ltd (Coffey) is pleased to present the results of the preliminary geotechnical investigation undertaken for Areas “A” and “C” at Long Bay Correctional Facility, Malabar. If you wish to discuss the report please contact the undersigned on 9911 1000.

For and on behalf of

COFFEY GEOSCIENCES PTY LTD

PETER WADDELL

Principal

Distribution:

Original held by Coffey Geosciences Pty Ltd

1 copy held by Coffey Geosciences Pty Ltd

8 copies to NSW Department of Commerce

E12723.3-AV 22 February 2005

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i

TABLE OF CONTENTS

1. INTRODUCTION 1

2. FIELD INVESTIGATION 2

3. LABORATORY TESTING 2

4. RESULTS OF INVESTIGATION 3

4.1 Site Description 3

4.1.1 Area A 3 4.1.2 Area C 3

4.2 Geological Setting 3

4.3 Subsurface Conditions 3

4.3.1 Area A 3 4.3.2 Area C 4

5. LABORATORY TEST RESULTS 5

6. DISCUSSION AND RECOMMENDATION 5

6.1 Earthworks 5

6.2 Foundations 6

6.3 Aggression to Concrete and Steel 7

6.4 Pavements 7

6.5 Soil Pre-planting Assessment 7

7. LIMITATIONS 7

Important Information About Your Coffey Report

E12723.3-AV 22 February 2005

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ii

FIGURES

Figure 1: Site Location Plan Figure 2: Area “A” Borehole Locations Figure 3: Area “C” Borehole Locations

APPENDIX A: Engineering Logs and Core Photographs

APPENDIX B: Other Consultants Engineering Logs

APPENDIX C: Laboratory Test Results

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1. INTRODUCTION This report details the results of a preliminary geotechnical investigation undertaken by Coffey Geosciences Pty Ltd (Coffey) for future possible developments in Areas “A” and “C” at the Long Bay Correctional Centre, Malabar. The work was undertaken for the NSW Department of Commerce in accordance with our proposal (Reference No. E12723/3-AD) dated 26 May 2004. The scope of work was increased to cover an increase in the land area (in Area A) to be investigated and this additional work was undertaken in accordance with our variation proposal (Reference No. E12723/3-AM) dated 24 September 2004. Investigation of proposed detention basin (OSD-5) in Area “A”, which formed part of the variation, is reported separately (Reference E12723.3-AX).

Two geotechnical investigations have been undertaken on the site by Coffey during the current investigation program. These geotechnical investigations were for the Proposed Central Store (Reference E12723.3-AO, dated 29 September 2004) in Area “C” and for the Proposed CSI Store and Workshop (Reference E12723.3-AN, dated 29 September 2004) in Area “A”. Reference should be made to these reports for details related to these specific developments.

It is understood that in addition to the Proposed Central Store in Area “C” and the Proposed CSI Store and Workshop and OSD-5 detention basin in Area “A”, another building is also proposed in Area “C”, with two possible locations of the new building being planned. Other developments, such as associated buildings and drainage works may also be considered in Area “A”.

The overall objective of the geotechnical investigation is to provide information of subsurface conditions, a geotechnical model together with discussion and recommendations on relevant geotechnical aspects including:

• A general description of the geology and geomorphology;

• Preliminary subsurface data;

• Suitability of excavated materials for re-use as fill for engineering and landscaping purposes;

• Preliminary recommendations on footing type, bearing capacities of foundations, earthworks and pavement design.

The investigation comprised:

• Drilling and sampling of geotechnical boreholes;

• Assessment of boreholes and hand auger holes drilled principally as part of the environmental assessment;

• Laboratory testing on selected samples.

Details of the preliminary geotechnical are presented in the report together with discussions and recommendations.

The investigation was undertaken in conjunction with a Phase 2 Environmental Site Assessment (ESA) and borehole information from the ESA has formed part of the preliminary geotechnical investigation. The Stage 2 ESA will be reported separately.

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2. FIELD INVESTIGATION

The field investigation was undertaken as a combined geotechnical and environmental assessment and comprised: • Drilling of 21 boreholes (identified as CBH1 to CBH4, CBH33 to CBH43, CBH45 to CBH50) in Area A

with the aid of a truck mounted drilling rig (see Figure 2);

• Collection of soil samples from 13 hand auger holes (identified as HA1 to HA13) in Area A with the aid of a hand auger (see Figure 2); and

• Drilling of 10 boreholes (identified as CBH5 to CBH7, CBH51 to CBH57) in Area C with the aid of a truck mounted drilling rig (see Figure 3);

For the boreholes drilled using the truck mounted rig, Standard Penetration tests (SPT’s) were undertaken at regular depth intervals to assess the engineering properties of the soils and to obtain samples. Disturbed auger samples were also obtained for laboratory testing purposes.

As part of the preliminary geotechnical investigation, coring of the bedrock was undertaken following the drilling, sampling and in-situ testing of the soil profile, in four of the boreholes. Two of the geotechnical boreholes were located in Area “A”, with the other two located in Area “C”. The depth of the geotechnical boreholes ranged from 4.25m to 5.2m.

For the environmental assessment, the boreholes were generally taken to 0.5m into natural soil or earlier V-bit refusal. These boreholes were also used in the geotechnical assessment. The depth of the environmental boreholes ranged from 0.5m to 3.5m.

The truck mounted drilling was undertaken between 1 September and 1 November 2004. The hand auger boreholes were drilled on 12 October 2004.

The field work was undertaken in the full time presence of a staff member from Coffey, who located the holes, nominated the sampling and testing and prepared filed logs of the materials encountered. Ground surface levels at the test locations have been interpolated from survey data provided by NSW Department of Commerce (Ref. Figure 2).

Engineering borehole logs are included in Appendix A, along with Explanation Sheets defining the terms and symbols used in their preparation.

Boreholes from previous investigations, by other consultants, were referenced in preparation of this report and copies of the engineering logs are provided in Appendix B.

3. LABORATORY TESTING

Rock core recovered from the boreholes was boxed and taken to our NATA registered laboratory for photographing and Point Load Strength Index testing. Photographs of the core are included in Appendix A, and Point Load Strength Index test results are shown on the engineering logs. Soil laboratory tests comprised:

• Particle size distribution tests - 4 tests

• Soaked California Bearing Ratio (CBR) – 2 tests

• Soil chemistry aggressivity (pH, sulphate and chloride) – 2 tests

• Soil pre-planting assessment suite of tests– 2 tests

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The results or the laboratory testing are presented in Appendix C.

4. RESULTS OF INVESTIGATION

4.1 Site Description

The site is located at Long Bay Correctional Complex, Malabar. Area “A” is located in the south eastern corner of the site near the boundary with Austral Street and Bilga Crescent. Area “C” is located in the southern part of the site and includes the building known as the Katingal Correctional Gaol. These areas are identified in Figure 1.

4.1.1 Area A

Area A is has an irregular shape comprising a rectangular shaped area to the north linked by a thin strip of land to a trapezoidal shaped area to the south, as shown on Figure 1. At the time of the investigation, there was a Boiler House and associated buildings, facilities and roads in the north western portion of the area. Ground surface levels generally slope downwards towards the east, varying from RL47.5m to RL35.5m.

4.1.2 Area C

Area C is rectangular in shape with an area of approximately 0.9ha. The main features of Area C at the time of the investigation included:

• The Katingal Correctional Gaol covers the majority of Area C. The Katingal gatehouse is located near the south-eastern boundary of Area C. The buildings have been constructed of concrete and the surrounding area including driveway is concrete paved;

• The north-eastern part of Area C including the roadway is relatively flat. The area is divided into two sections by a crib wall where the remaining area slopes moderately down to the south-west.

Ground surface levels generally slope downwards towards the southwest, varying from RL42.5m to RL34.5m. Areas to the north of the Katingal building are covered by grass with some trees, while areas to the south of the Katingal building are concrete paved and utilised as a car park.

4.2 Geological Setting

Based on the Sydney 1:100,000 Geological Series Sheet the site is underlain by Triassic Period Hawkesbury Sandstone and borders Botany Basin Quaternary deposits. The Hawkesbury Sandstone generally comprises fine to coarse grained quartzose sandstone deposited in 1m to 3m thick beds and lenses and may be overlain by aeolian dune or beach deposited sands.

4.3 Subsurface Conditions

For details of the conditions encountered in the boreholes, reference should be made to the engineering logs. Areas “A” and “C” are not adjacent and encountered differing subsurface conditions and are therefore discussed separately in the following sections.

4.3.1 Area A

As part of the current investigation, 21 boreholes and 13 hand auger holes were located within Area A. In summary, the boreholes encountered fill over dune deposits and then sandstone bedrock. A summary of the Area A subsurface strata units encountered is provided in Table 1.

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The top of sandstone levels are highest in the north western corner at approximately RL46m AHD and fall to the south and east to approximately RL33m AHD.

Table 1 Area A Subsurface Strata Units Summary

Strata Unit Description

Fill Silty sand and clayey sand, with crushed concrete and brick rubble and coal ash encountered in some of the boreholes. Ranges in thickness from 0m to 0.9m.

Dune Deposits Sand – fine to medium grained, generally loose to medium dense, although very loose to loose and very dense conditions were encountered in some of the boreholes. Up to 3.1m thick.

Residual Sandy clay – very stiff. Only encountered in CBH48 with a thickness of 1.1m.

Bedrock Sandstone was cored in CBH2 and CBH3 and was inferred from V bit / TC bit / SPT refusal in 11 of the remaining 19 boreholes. Encountered at depths ranging from 1.2m to 3.5m. The sandstone in CBH2 and CBH3 was moderately to highly weathered in the upper 0.5m and 0.2m respectively and then medium strength.

Groundwater was encountered within 7 of the boreholes during auger drilling at depths ranging from 1.7m to 2.0m below existing surface levels.

4.3.2 Area C

As part of the current investigation, 10 boreholes were located within Area D. In summary, the boreholes encountered fill over dune deposits and then sandstone bedrock. A summary of the Area C subsurface strata units encountered is provided in Table 2.

The top of sandstone levels are highest on the eastern side at approximately RL41m AHD and fall to the west to approximately RL33.5m AHD.

A summary of the Area D subsurface strata units encountered is provided in Table 1.

Table 2 Area C Subsurface Strata Units Summary

Strata Unit Description

Fill Gravely silty sand and clayey sand. Typically less than 0.7m thick but 2.2m thick in CBH56.

Dune Deposits Sand – fine to medium grained, generally loose to medium dense. Ranges in thickness from 0m to 1.1m.

Bedrock Sandstone was cored in CBH5 and CBH6 and was inferred from V bit / TC bit refusal the remaining boreholes except CBH56. Encountered at depths ranging from 0.5m to 2.2m. The sandstone in CBH5 was moderately to highly weathered in the upper 1.0m and then medium strength. The sandstone core recovered from CBH3 contained substantial core losses in the upper 2.1m and then medium to high strength.

Groundwater was encountered at 2.2m depth during auger drilling in CBH56 only.

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5. LABORATORY TEST RESULTS

For details of the laboratory test results, reference should be made to the test results certificates provided in Appendix C. The results, excluding the pre-planting assessment are summarised in Table 3.

Table 3 Summary of Laboratory Test Results

Bore

hole

Dept

h (m

)

Sample Description

FMC

(%)

SOMC

(%)

SMDD

(t/m

3 )

CBR

(%)

pH

Sulp

hate

(% H

2O S

ol)

Chlo

ride

(%

H2O

Sol

)

CBH2 0.5 Gravely sand, some clay 6.6 0.002 0.003

CBH3 1.0 Sand – fine to medium grained, some clay *

CBH6 0.5 Sand – medium grained 6.2 <0.001 0.19

CBH7 0.8 Sand – medium grained *

Site A 0.2 – 0.6 Sand – fine to medium grained 6.7 15.2 1.63 11

Site C 0.2 – 0.6 Silty Gravely Sand 10.9 13.0 1.82 19

* Grading only FMC Field Moisture Content SOMC Optimum Moisture Content SMDD Standard Maximum Dry Density CBR California Bearing Ratio - 4 day soaked, 100%SMDD, SOMC, 4.5kg surcharge pH Acidity

The pH results indicate that the soils are slightly acidic. The sulphate and chloride test results indicate that the soil conditions are mild to non-aggressive to steel and concrete piles.

The results of the pre-planting assessment together with a summary and recommendations are provided on the report sheets by Sydney Environmental and Soil Laboratory, also included in Appendix C.

6. DISCUSSION AND RECOMMENDATION

6.1 Earthworks

The fill and dune deposits should be able to be excavated using hydraulic excavators and tracked loaders. Large hydraulic excavators with the assistance with rock breakers will be required to excavate the sandstone. If vibration sensitive structures are within close proximity to the excavations it may be necessary to restrict the use of rock breakers, or use rock saws or milling heads to limit vibrations.

Due to the variability and uncontrolled nature of the existing filling on the site it is recommended that the existing filling below proposed building areas be removed. Subgrade preparation of natural soils for foundation or pavement construction should include the following:

• Strip all fill and stockpile suitable materials for re-use, if required. The fill material is generally considered suitable for reuse as structural fill material; however, its use will be dependent on its environmental classification.

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• Proof roll the exposed surface of natural material. Excavate localised soft spots and replace with suitable fill, compacted to a minimum dry density ratio of 98% Standard Compaction at a moisture content within ± 2% of Standard Optimum Moisture Content. If fill with low fines (< 5% silt and clay) is used it should be compacted to a minimum Density Index of 70%.

• Compact the exposed subgrade soils to a minimum dry density ratio of 98% Standard Compaction (or 70% Density Index).

Any new filling should be placed in layers (not exceeding 300 mm loose thickness) and compacted to a minimum dry density ratio of 98% Standard Compaction at a moisture content within ± 2% of Optimum Moisture Content or 70% Density Index for low fines fill material.

Permanent batter slope angles within controlled filling or natural sands should be no steeper than 2H:1V for batter heights up to 3 m. Fill batters should be overfilled and trimmed back to profile. Soil batters should be vegetated (or covered by shotcrete, stone pitching or similar) to prevent erosion. Sandstone batters could be cut near vertical but should be inspected by a suitably qualified engineer to assess whether flatter angles or support measures such as shotcrete or rock bolts are required.

6.2 Foundations

Strip and pad footings or bored piles should be suitable to support structural loads. Open bored piles should be feasible, however, cohesionless sands could be encountered and/or seepage could occur and provision for measures such as temporary liners, dewatering and cleaning of open bored piers will be required. Alternatively, continuous flight auger (CFA) piles could be adopted, which do not require cleaning and dewatering.

Table 4 presents parameters for the preliminary design of footings bearing on controlled fill, loose to medium dense sand and sandstone. To reduce differential settlement it is recommended that all foundations be extended to the sandstone. If a shallow foundation system is to be adopted within variable foundation strata, consideration will need to be given to likely differential settlement. As a guide to likely settlements it could be assumed that footings founding in sands or filling, with a working load of 100kPa, will settle approximately 1% of the minimum footing dimension (eg approximately 10mm for a 1m wide footing) while footings founding on sandstone with working load of 100kPa would have little settlement.

Table 4: Preliminary Allowable Footing Design Parameters

Geotechnical Unit Rock Class Allowable End Bearing Pressure (kPa) (2)

Allowable Shaft Adhesion (kPa) (3)

Controlled Filling, Sands (Loose to medium dense) - 100 Nil

Class V 1000 100 Hawkesbury Sandstone

Class IV or III 1,000 to 3,500 (3) 200 to 350 (4)

Notes: (1) Rock classified in accordance with Pells et al (1998) (2) Allowable bearing pressures assume a minimum embedment of 0.3m into the relevant material. The recommended end bearing pressures should result in settlement of <1% of minimum footing dimension. (3) Shaft adhesion should only be assigned where piles are socketed at least 3 diameters into rock. (4) The higher value could be used if rock is further assessed by spoon testing or additional coring at the time of construction.

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6.3 Aggression to Concrete and Steel

The results of the chemical testing and reference to Tables 6.1 and 6.3 of the Australian Standard AS 2159-1995 “Piling – Design and Installation” indicates the sample tested can be considered mild to non-aggressive to concrete and steel.

6.4 Pavements

Laboratory test results indicated soaked CBR values of 11% and 19% for a sand and a gravely sand sample, respectively, collected between 0.2m and 0.6m depth. The relatively high CBR value for the gravely sand would be due to the gravel content in the sample. As the gravel content in the natural soils is variable we recommend a lower CBR value be adopted for design.

Provided earthworks are undertaken as indicated in Sectio 7.1 of this report, it is recommended that design of flexible or rigid pavements on a compacted sand subgrade for this site be designed on a CBR value of 10%.

6.5 Soil Pre-planting Assessment

For details of the results and recommendations for soil planting reference should be made to the soil pre-planting assessment results by Sydney Environmental and Soil Laboratory, which are provided in Appendix C. In summary the soils are suitable for planting provided treatment and additives as recommended on the test results sheets are followed.

7. LIMITATIONS

The recommendations presented in this report are based on limited subsurface investigations. Ground conditions can change over relatively short distances and additional geotechnical advice may be required during construction to assess whether conditions are consistent with design assumptions. Coffey would be pleased to provide additional advice and construction stage services, if required.

The attached document entitled “Important Information about your Coffey Report” provides additional information on the uses and limitations of this report.

For and on behalf of COFFEY GEOSCIENCES PTY LTD

PETER WADDELL Principal

E12723.3-AV 22 February 2005

APPENDIX A – AREA A

ENGINEERING LOGS AND CORE PHOTOGRAPHS

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APPENDIX A – AREA C

ENGINEERING LOGS AND CORE PHOTOGRAPHS

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APPENDIX B – AREA A

OTHER CONSULTANTS ENGINEERING LOGS

E12723.3-AV 22 February 2005

APPENDIX B – AREA C

OTHER CONSULTANTS ENGINEERING LOGS

E12723.3-AV 22 February 2005

APPENDIX C

LABORATORY TEST RESULTS