Geotechnical Testing Services · earth pressure co-efficient is recommended. If it is critical to...

GTE1437 – Geotechnical Report 15 November 2018 Client: Tilrox Pty Ltd c/- Design Cubicle 44 Sorrell Street North Parramatta, NSW, 2151 RE: GEOTECHNICAL INVESTIGATION at Lot No.1 DP 1097685; Vardys Road, Kings Langley

This letter presents a geotechnical report on the inspection and testing services associated with the geotechnical investigation undertaken at the above project.

Should you have any questions related to this report please do not hesitate to contact the undersigned.

For and on behalf of Ground Technologies Pty Ltd

Reviewed By

A. Bennett J. Harendran Princiapal Geotechnical Engineer Senior Geotechnical Engineer

GROUND TECHNOLOGIES

Ground Technologies Pty Ltd ABN 25 089 213 294 PO Box 1121 Green Valley NSW 2168 Ph: (02) 8783 8200 Fax: (02) 8783 8210

Email: [email protected]

Geotechnical Testing Services

GTE1347 -2- Kings Langley

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Table of Contents 1. INTRODUCTION ............................................................................................................................... 3

1.1 Site Details ............................................................................................................................... 3 1.2 Geology .................................................................................................................................... 3 1.3 Site Description ........................................................................................................................ 4 1.4 Proposed Development ............................................................................................................ 5

2. GEOTECHNICAL INVESTIGATION ................................................................................................. 6 2.1 Soil Profiles .............................................................................................................................. 6 2.2 Groundwater ............................................................................................................................. 7 2.3 Soft Soils .................................................................................................................................. 7

3. GEOTECHNICAL DESIGN RECOMMENDATIONS ......................................................................... 7 3.1 Batter Slopes ............................................................................................................................ 7 3.2 Retaining Wall Design Parameters ........................................................................................... 7 3.3 Bored Pier Footings .................................................................................................................. 8 3.4 Excavation ................................................................................................................................ 8 3.5 Perched Water Seepage .......................................................................................................... 9 3.6 Basement Level Footings ......................................................................................................... 9 3.7 Basement Level Subgrade ....................................................................................................... 9

4. CONDITIONS OF THE RECOMMENDATIONS AND LIMITATIONS ............................................. 10 5. REFERENCES ................................................................................................................................ 10 APPENDIX A BOREHOLE LOGS


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1. INTRODUCTION Ground Technologies Pty Ltd (Ground Tech) has prepared this report to discuss the results of the geotechnical investigation undertaken for the proposed residential development at Lot No.1 DP 1097685; Vardys Road, Kings Langley (herein referred to as the “site”). Ground Tech was engaged to provide professional assistance for this component of the project. The geotechnical investigation included six (6) boreholes using a 4WD Toyota Landcruiser Ute mounted drill rig with 100mm diameter solid flight spiral augers at the locations shown on drawing Figure 4. This report provides a geotechnical assessment on the existing soil conditions. This report is based only on the information provided at the time of this report preparation and may not be valid if changes are made to the site or to the construction method. 1.1 Site Details The following information, presented in Table 1, describes the site.

Table 1: Summary of Site Details

Figure 1 – Location of Site

1.2 Geology The 1:100,000 scale Geological Series Map of the Sydney region indicates that the subject site is underlain by Bringelly Shale of the Wianamatta Group dating back to the Middle Triassic period and generally comprises shale, carbonaceous claystone, claystone, laminate, fine to medium grained lithic sandstone, and rare coal / tuff.

Site Address Vardys Road, Kings Langley Lot / DP Lot 1 DP1097685 Council Area Blacktown City Council


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1.3 Site Description The subject site is located on the north-eastern corner of the intersection of Sunnyholt Road and Vardys Road. The site is near rectangular in shape, measuring approximately 180m along the Vardys Road frontage and approximately 90m along the Sunnyholt Road frontage. The site is currently vacant, however an unnamed creek / drainage line traverses through the site in an east to west direction. The proposed development will encroach into this creek requiring the drainage path to be re-aligned, as shown in figure 2. It is assumed that the drainage channel will be re-aligned prior to the commencement of construction.

Figure 2 – Existing Drainage Line and Proposed Re-zoning

Photograph 1 – Drainage Line (Western Portion of Site)

Existing Drainage Line


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Photograph 2 – Main Portion of Site to the South of Drainage Line

1.4 Proposed Development It is understood that the proposed development will comprise the construction of two apartment buildings (five levels high) with two levels of basement car parking. It is further understood that excavations of between 3.7-9.7m will be required in order to accommodate the basement level car park. It is assumed that the drainage channel will be re-aligned prior to the commencement of construction.

Figure 3 – Proposed Site Plan and Sections


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2. GEOTECHNICAL INVESTIGATION Fieldwork was undertaken on the 13th of December 2017 and included drilling six (6) boreholes with a 4WD Toyota Landcruiser Ute mounted drill rig with 100 mm solid flight spiral augers at the locations shown on Figure 4. Full borehole logs are presented in Appendix A.

Figure 4 – Borehole Locations

2.1 Soil Profiles Four (4) distinct geological units were encountered during the field investigation. These units are detailed in table 2 and the approximate depth of each unit is detailed in table 3:-

Table 2: Summary of Geological Units

UNIT SOIL TYPE

UNIT A FILL: comprising admixed silty clay with gravel or admixed silt, sand, gravel, clay

UNIT B NATURAL: Alluvial Silt, Sand Clay matrix. The upper 1-2m being dry to slightly moist and stiff to very stiff. The lower portion being very moist to wet and soft to stiff

UNIT C NATURAL: Silty Clay / Completely Weathered Rock, medium to high plasticity, moist, very stiff.

UNIT D BEDROCK: Assumed as Shale, extremely weathered, medium strength (or better)

Table 3: Depth of each Geological Unit

Borehole Geological Unit

Unit A Unit B Unit C Unit D

BH01 - 0-6.0m - 6.0m+ BH02 - 0-5.8m - 5.8m+ BH03 0-1.2m 1.2-5.7m 5.7-6.7m 6.7m+ BH04 - 0-6.0m - 6.0m+ BH05 0-1.4m 1.4-5.6m 5.6-6.6m 6.6m+ BH06 0-1.5m 1.5-5.6m 5.6-6.4m 6.4m+

Drainage Line

Building Envelope

2

1

3

4

5

6


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2.2 Groundwater Groundwater was not encountered during the course of the investigation, however perched water was observed within the alluvial soil matrix. During wet months or following significant rainfall events, development of “perched” groundwater will occur in this soil profile, resulting in localized wetting or saturation of the natural alluvial soils which overlie the shale bedrock interface. Soils were observed as being over optimum moisture contents at depths varying between 1.2m (BH4) and 4.0m (BH6). Free water was observed within borehole BH2 at a depth of 5.0m. Given that the site contains a natural drainage path, the levels of groundwater experienced will significantly vary between seasonal and one-off rainfall events. As such, this perched groundwater system will affect excavations for the basement to be built within the site. The basement should be designed as a tanked structure. 2.3 Soft Soils Unit B was observed as having a high silt and sand content. These materials will rapidly lose shear strength with slight moisture changes. As such these materials are considered to be unsuitable as pavement subgrades or founding profiles for structural footings. 3. GEOTECHNICAL DESIGN RECOMMENDATIONS 3.1 Batter Slopes We understand that deep excavation will form part of the development. Temporary excavation within the fill and alluvial matrix (Units A to B) should be battered at an angle of 45°. 3.2 Retaining Wall Design Parameters Where the excavation is not battered as per section 3.1 of this report, pile installation should precede basement construction. They will initially act in a cantilever capacity but will, subsequent to basement construction, be tied via a capping beam to a suspended floor which will provide lateral support to the piles. For the design of flexible retaining structures, where some lateral movement is acceptable, an active earth pressure co-efficient is recommended. If it is critical to limit the horizontal deformation of a retaining structure, use of an earth pressure co-efficient at rest should be considered. Recommended parameters for the design of retaining structures are presented in table 4.

Table 4: Retaining Wall Design Parameters for each Geological Unit

Geological Unit

Unit A to C Unit D Fill and

Natural Soils Bedrock

Ka 0.5 0.2

Ko 0.66 0.3

Kp 2.0 300kPa

Unit Weight (kg/m3) 18 22 The retaining wall designs should also allow for any additional surcharge loads from adjoining structures, vehicles etc, which should be calculated separately. Allowances should be made for water proofing the wall to allow for potential groundwater tables.


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3.3 Bored Pier Footings Bored concrete piers, socketing can be designed in accordance with the end bearing capacities detailed in table 5.

Table 5: Allowable Bearing Capacity for Bored Piers

Soil Type Allowable Bearing Capacity Shaft Adhesion

Medium Strength Bedrock (Unit D) 1000kPa 100kPa The quality of the founding stratum in all footing excavations is to be assessed by a geotechnical engineer to confirm that the design parameters recommended in this report are appropriate. Footing excavations are to be cleaned out and inspected by a geotechnical engineer or the structural engineer prior to concrete placement. Concrete is to be placed within 24 hours of excavation, since the weathered bedrock may deteriorate rapidly upon exposure. Note: Bearing capacities detailed in table 5 are conservative. Higher capacities may be achieved if further investigation with NMLC rock coring techniques are undertaken to confirm the rock strength. 3.4 Excavation Excavations within units A to C should be achieved with bucket attachment to a mid sized excavator. Excavations within Unit D and below drill rig refusal, intersecting more competent bedrock may require pre-loosening using rock breaking or ripping attachments. If vibratory rock breaking equipment is required for the proposed excavations in sandstone bedrock we recommend that, prior to the use of vibratory equipment, the excavation perimeter is saw cut with the aid of an excavator mounted rock saw or by drill and split techniques so as to minimise transmission of vibrations to adjoining structures. Following sawing of the perimeter of the excavation, sandstone bedrock may be broken up using a vibratory hammer suited to an excavator. At the time of the investigation, no structures were situated near the proposed basement excavations, however should there be structures at the time of construction, induced vibrations in structures adjacent to the excavation are to be examined to ensure that they do not exceed a peak particle velocity (PPV) of 5mm/sec. As a guide, safe working distances for typical items of vibration intensive plant are listed in Table 6. The safe working distances are quoted for “cosmetic” damage (refer BS 7385) and are detailed in the Construction Noise Strategy (2010) prepared by the NSW Transport Construction Authority.

Table 6: Recommended Safe Working Distances for Vibration Intensive Plant Plant Item Rating / Description Safe Working

Distance Small Hydraulic Hammer 250kg – 1.5 tonne excavator 2m Small Hydraulic Hammer 300kg - 5 to 12tonne excavator 2m Medium Hydraulic Hammer 900kg - 12 to 18tonne excavator 7m Large Hydraulic Hammer 1600kg - 18-34 tonne excavator 22m


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Ground vibrations induced by excavations should be monitored and recorded by specialist contractors. Monitoring equipment / data loggers should be installed at the closest point of the adjacent structures to ensure that the excavation contractor does not exceed the recommended level. We recommend the operation of hydraulic hammers should include:

• Excavation of loose or rippable sandstone blocks by bucket or single ripper attachments prior to the commencement of rock hammering;

• Use of saw cutting around the perimeter • Progressive breakage from open excavated faces; • Selective breakage along open joints where these are present; • Use of rock hammers in short bursts to prevent generation of resonant frequencies; • Orientation of the rock hammer pick away from property boundaries and into existing open

excavation; • The movement of large blocks away from the structures prior to breaking up for transport from

the site. Excavation works should be carried out by an experienced operator who is aware of factors affecting vibration and transmission of vibration such as orientation of the hammer, duration of hammering and speed of the vibration of the hammer. Prior to the excavation works, it is recommended that dilapidation surveys be undertaken out on the surrounding structures (if any) as a means of protecting all parties involved in or affected by the proposed works. 3.5 Perched Water Seepage Permanent groundwater was not encountered during this investigation. However, seepage should be expected from any temporary perched ground water table. This seepage is expected to be intermittent and recharged by rainfall events, and should be sufficiently managed during the construction phase by pumping from a sump at the base of the excavation. In the long term, conventional techniques such as strip drains behind basement walls and ag-lines will need to be incorporated into the design of the basement, along with a sump and pump system linked to the regional stormwater system. The basement should be designed as a tanked structure. 3.6 Basement Level Footings Excavations for the basement level of the apartment building will extend to approximately 3.7-9.7m below existing ground surface levels across the majority of the footprint. Material exposed at the base of this excavation will comprise a combination of Units B through D. Unit B, the soft to stiff alluvial matrix, is considered unsuitable as a founding stratum. As such, all internal footings will be required to found on bedrock. Footing design parameters are supplied in section 3.2 of this report. 3.7 Basement Level Subgrade Excavations for the basement level of the apartment building will extend to approximately 3.7-9.7m below existing ground surface levels across the majority of the footprint. Material exposed at the base of this excavation will comprise a a combination of Units B through D. Unit B, the soft to stiff alluvial matrix, is unsuitable for short-term loading by piling rigs etc and long term loading by a car parking pavement. As such, this subgrade will need to be mechanically improved with the usage of geo-fabrics, geo-grids and imported crushed rock. Specialist advice will need to be provided during the construction stage by a suitable contractor.


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4. CONDITIONS OF THE RECOMMENDATIONS AND LIMITATIONS This report is a geotechnical report only and the classification stated shall not be regarded as an engineering design nor shall it replace a design by engineering principles although it may contribute information for such designs. When this report is to be used as a reference by the engineer or builder or other relevant party, this report must be reproduced in total. The foundation depths quoted in this report are measured from the surface during our testing and may vary accordingly if any filling or excavation works are carried out. The description of the foundation material for has been provided for its easy recognition over the whole building site.

Any sketches in this report should be considered as only an approximate pictorial evidence of our work. Therefore, unless otherwise stated, any dimensions or slope information should not be used for any building cost calculations and/or positioning of the building. Dimensions on logs are correct. This type of investigation (as per our commission) is not designed or capable of locating all ground conditions, (which can vary even over short distances). The advice given in this report is based on the assumption that the test results are representative of the overall ground conditions. However, it should be noted that actual conditions in some parts of the site might differ from those found. If excavations reveal ground conditions significantly different from those shown in our findings, Ground Tech must be consulted. The scope and the period of Ground Tech services are described in the report and are subject to restrictions and limitations. Ground Tech did not perform a complete assessment of all possible conditions or circumstances that may exist at the Site. If a service is not expressly indicated, do not assume it has been provided. If a matter is not addressed, do not assume that any determination has been made by Ground Tech in regards to it. Where data has been supplied by the client or a third party, it is assumed that the information is correct unless otherwise stated. No responsibility is accepted by Ground Tech for incomplete or inaccurate data supplied by others. This document is COPYRIGHT- all rights reserved. No part of this document may be reproduced or copied in any form or by means without written permission by Ground Technologies Pty Ltd. All other property in this submission shall not pass until all fees for preparation have been settled. This submission is for the use only of the party to whom it is addressed and for no other purpose. No responsibility is accepted to any third party who may use or rely on the whole or any part of the content of this submission. No responsibility will be taken for this report if it is altered in any way, or not reproduced in full. This document remains the property of Ground Technologies Pty Ltd until all fees and monies have been paid in full. 5. REFERENCES

• AS2870 (2011), Residential Slab and Footings – Construction • Geological Series Sheet 9030 (EDITION 1) 1991, Map of the Penrith region, scale 1:100,000 • “Foundations of Sandstone and Shale in the Sydney Region” by P.J.N Pells, G.Mostyn & B.F

Walker. • Australian Standards AS2159 – 2009 Pilling – Design and Installation

APPENDIX A BOREHOLE LOGS

N ML Sandy SILT, orange/brown, dryIL

Clayey SILT, brown, pale brown, with minor orange, dry

CI Very Silty CLAY, with minor ironstone gravel,medium plasticity, mottled orange, yellow and pale grey,

dry, very stiff

Very Silty CLAY, with minor ironstone gravel,medium plasticity, mottled grey, orange, yellow,

very moist to wet, soft

Silty Sandy CLAY, with ironstone gravel,medium plasticity, mottled brown, grey, orange, yellow,


Silty Sandy CLAY, with ironstone gravel,medium plasticity, mottled pale grey and orange,

very moist to wet, softSC/CI Sandy CLAY / Clayey SAND, with ironstone gravel,

brown, dark brown with minor orange and grey,very moist to wet, firm to stiff

ROCK BEDROCK, assumed as shale, medium strength

Borehole terminated at 6.2mdue to drill rig refusal on bedrock

100

Site Location Vardy Road, Kings LangleyLot / DP Lot 1 DP1097685

<100

13/12/2017Solid Flight Auger

DateMethod

0.5

<100

<100

1

3

1.5

2

2.5

6.5

4

4.5

5

5.5

GRA

PHIC

LO

G

SOIL DESCRIPTION (SOIL TYPE, COLOUR, MOISTURE, CONSISTENCY ) U

NIF

IED

CLAS

SIFI

CATI

ON

DEPT

H (m

)

REMARKS

POCK

ET

PEN

ETRO

MET

ER

WAT

ER

Starting R/L - approx. 45.5m

3.5

<100

7

Bedrock R/L - approx. 39.5mInstant refusal on bedrock

6

100

Borehole No. 1

170

GROUND TECHNOLOGIES Geotechnical . Environmental . Laboratories

ML Clayey SILT, orange/brown, dry

Sandy SILT, orange/brown, dry

CI Very Silty CLAY, with very minor ironstone gravel,medium plasticity, mottled pale grey, orange and orange/brown,

moist, stiff to very stiff

Very Silty CLAY, medium plasticity, mottled pale grey and orange,

very moist, soft to firm

Very Silty CLAY, medium plasticity, mottled pale grey, orange and dark grey,

very moist, soft to firm

SC/CI Sandy CLAY / Clayey SAND, with ironstone gravel,brown, dark brown with minor orange and grey,

very moist to wet, firm to stiff



7

6.5

6

Free water at 5.0m

100

4

4.5

5

5.5

<100

3.5

3<100

2.5

2<100

1.5

1120

0.5


Borehole No. 2

WAT

ER

DEPT

H (m

)

UN

IFIE

D CL

ASSI

FICA

TIO

N

SOIL DESCRIPTION (SOIL TYPE, COLOUR, MOISTURE, CONSISTENCY )

GRA

PHIC

LO

G

POCK

ET

PEN

ETRO

MET

ER

REMARKS


Site Location Vardy Road, Kings LangleyLot / DP Lot 1 DP1097685Date 13/12/2017Method Solid Flight Auger


N FILL Admixed Silt, sand, Gravel, Clay,I brown, pale brown, pale grey, orangeL

ML Clayey Sandy SILT, pale brown, pale grey/brown, dry, stiff

Clayey SILT, with minor sand,yellow/brown with pale grey, very moist, soft

SC / CI Sandy CLAY / Clayey SAND, with ironstone gravel,brown, dark brown with minor orange and grey,


CI/CH Silty Clay / Completely Weathered Rock,medium to high plasticity, pale grey with minor yellow mottling,

slightly moist to moist, very stiff




7

280

6.5

6300

4

4.5

5

5.5

100

<100

3.5

3

2.5 <100

2

1.5 120

1

0.5

POCK

ET

PEN

ETRO

MET

ER

REMARKS


Method Solid Flight AugerBorehole No. 3

WAT

ER

DEPT

H (m

)

UN

IFIE

D CL

ASSI

FICA

TIO

N


GRA

PHIC

LO

G

Site Location Vardy Road, Kings LangleyLot / DP Lot 1 DP1097685Date 13/12/2017


N ML Clayey SILT, pale grey/brown, dryIL

CI Silty CLAY, medium plasticity, yellow/brown,dry, very stiff

CI Very Silty CLAY, with minor sand,medium plasticity, pale grey and red with minor yellow,

very moist, soft

ML Clayey Sandy SILT, yellow/brown with pale grey mottling,very moist, soft

Clayey Sandy SILT, red with pale grey mottling,very moist, soft

SC/CI Silty Sandy CLAY, with ironstone gravel,medium plasticity, mottled pale grey and orange,


Sandy CLAY / Clayey SAND, with ironstone gravel,brown, dark brown with minor orange and grey,




Site Location Vardy Road, Kings LangleyLot / DP Lot 1 DP1097685Date 13/12/2017Method Solid Flight AugerBorehole No. 4

WAT

ER

DEPT

H (m

)

UN

IFIE

D CL

ASSI

FICA

TIO

N

SOIL DESCRIPTION (SOIL

TYPE, COLOUR, MOISTURE, CONSISTENCY )

GRA

PHIC

LO

G

POCK

ET

PEN

ETRO

MET

ER

REMARKS


0.5

2801

>1001.5

2>100

2.5

3

3.5>100

4

4.5

5

5.5 120

6.5


100

6

7


N FILL Admixed Silty Clay with minor gravel,I brown, pale brown, pale grey, orangeL

ML Very Silty CLAY, with minor ironstone gravel,medium plasticity, dark brown, slightly moist, stiff

CI Silty Clay, medium plasticity,orange/brown with red/brown mottling,

slightly moist, stiff to very stiff

Silty Clay, medium plasticity, yellow/brown with minor pale grey mottling,


…becoming very moist and stiff..

…becoming very moist and soft…






WAT

ER

DEPT

H (m

)

UN

IFIE

D CL

ASSI

FICA

TIO

N


GRA

PHIC

LO

G

POCK

ET

PEN

ETRO

MET

ER

REMARKS


0.5

1

1.5 100

2220

2.5

3

3.5200

4

4.5

5

5.5

6.5

6


7

260

130

<100


N FILL Admixed Silty Clay with minor gravel,I brown, pale brown, pale grey, orangeL

ML Very Silty CLAY, with minor ironstone gravel,medium plasticity, dark brown, slightly moist, stiff

CI Silty Clay, medium plasticity,orange/brown with red/brown mottling,


Silty Clay, medium plasticity, yellow/brown with minor pale grey mottling,


…becoming very moist and stiff..

…becoming very moist and soft…



ROCK BEDROCK, assumed as shale, medium strength Bedrock R/L - approx. 41.1mInstant refusal on bedrock



WAT

ER

DEPT

H (m

)

UN

IFIE

D CL

ASSI

FICA

TIO

N


GRA

PHIC

LO

G

POCK

ET

PEN

ETRO

MET

ER

REMARKS


0.5

1

1.5120

2240

2.5

3 180

3.5

4120

4.5

>100

5

5.5

320

6.5

6340

7


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