Geotechnical investigation for Tomkinson · 2020. 11. 24. · sites south-eastern boundary. This was generally confirmed by the field data. 3 FIELDWORK The geotechnical investigation

Sandhurst Geotech Pty Ltd, Trading as Geotechnical Testing Services – Southern. ABN: 18 169 924 109 ACN: 169 924 109

Email: [email protected]; Ph: 03 5441 4881; Fax: 03 5441 5089; Mail Address: PO Box 13, STRATHDALE, Vic, 3550

Offices: La Trobe University Applied Science 2 Building 7 Sharon Street, Flora Hill, VIC 3550; Shed 3, 140 Ogilvie Avenue, Echuca , VIC 3654,

Geotechnical Investigations Contract Drilling Land Capability Assessments Contamination Assessments Compaction Control Testing On-site Wastewater Management Site Classifications Residential and Industrial Soil, Concrete and Aggregate Testing Laboratories Site Laboratory

Construction Material Testing Services www.geotestsouthern.com.au

Proposed Sewer Alignment

Dukes Lane, Strathfieldsaye

Geotechnical investigation for Tomkinson

Report 20C 1181 October 2020

Dukes Lane, Strathfieldsaye

Geotechnical Investigation for

Tomkinson

Revision

Revision Authorised Date

20C 1181 SEH 26/10/20

Distribution (this version only)

Recipient Format Date

GTS On file 26/10/20

Tomkinson Attn: Matt Elliot

Email PDF [email protected]

26/10/20

Geotechnical Testing Services – Southern Report: 20C 1181 Report

TABLE OF CONTENTS

1 INTRODUCTION ......................................................................................................... 1

2 SITE AND GEOLOGY ................................................................................................. 1

2.1 SITE LOCATION AND GENERAL CONDITIONS ................................................ 1

2.2 GEOLOGY ............................................................................................................ 1

3 FIELDWORK ............................................................................................................... 1

4 DISCUSSION ............................................................................................................... 3

5 IMPORTANT NOTES ABOUT THIS REPORT ............................................................ 4

6 DISCLAIMER ............................................................................................................... 4

APPENDIX

Site Plan Engineering Logs Descriptive Terms

Geotechnical Testing Services – Southern Page 1 Report: 20C 1181 Report

1 INTRODUCTION

Tomkinson commissioned Geotechnical Testing Services (GTS) to undertake a geotechnical

investigation for the proposed sewer pipeline at Dukes Lane, Strathfieldsaye.

The purpose of the investigation was to assess general subsurface conditions at the site with a view

to providing comments and design parameters for the proposed construction.

2 SITE AND GEOLOGY

2.1 SITE LOCATION AND GENERAL CONDITIONS

The site is located on the western side of Dukes Lane, Strathfieldsaye.

The site has a slight fall to the west and is currently vacant. Sheepwash Creek forms the western

boundary of the site. At the time of the investigation, the surface of the site was moist with a good

coverage of seeded and natural grasses. There were many small to large sized trees surround the

road and creek reserve bordering the investigation site. There was no visual evidence of surface

cracking or exposed surface rock.

2.2 GEOLOGY

The Victorian Government’s online “Geovic” map shows the site to be underlain by Quaternary aged

alluvial deposits, with Ordovician aged sedimentary deposits of the Castlemaine group towards the

sites south-eastern boundary. This was generally confirmed by the field data.

3 FIELDWORK

The geotechnical investigation was conducted on the 8 of October 2020 and involved the drilling of

3 boreholes by a Gemco drilling rig to depths of 4.5 to 9.3 metres. Pocket Penetrometer (PP) tests

were conducted in the boreholes with the results included on the engineering logs.

It is noted that a 4th borehole was proposed, however that area was too wet for access.

The field investigation was conducted by a technician under the direction of a Geotechnical

Engineer, who logged the subsurface profile and determined the testing program. The engineering

logs are included in the Appendix with their locations as designated by the client shown on the

enclosed site plan.

Geotechnical Testing Services (Southern) Report: 20C 1181 Report

Page 2

The field investigation indicated that the soil profile is variable across the site, but typical of an alluvial

profile and may be summarized as follows:

Borehole 1

(Gravelly) Silty CLAY, medium plasticity, brown, pale brown, black, dark grey, stiff to very stiff

to a depth of 3.2 metres

Overlying

(Gravelly) Silty CLAY, dark grey, mottled brown, orange brown, soft

To termination at 4.5 metres

Borehole 2

FILL: Clayey Sandy SILT, fine to medium, brown, low plasticity, medium dense

To a depth of 0.2 metres

Overlying

Silty CLAY, medium plasticity, brown, mottled brown, pale brown, stiff,


Overlying

Clayey SAND & Clayey Sandy GRAVEL, fine to coarse, brown, orange/brown, medium dense


Overlying

Silty CLAY, low plasticity, pale grey, stiff,


Overlying

SILTSTONE, extremely weathered, pale grey, low to moderate strength

To refusal depth of 9.3 metres

Borehole 2

FILL: Clayey Sandy SILT, fine to medium, brown, low plasticity, medium dense

To a depth of 0.1 metres

Overlying

Clayey/Gravelly SAND, fine to medium, orange/brown, medium dense to dense


Overlying

SILTSTONE, extremely weathered, off white, low strength

To termination depth of 3.0 metres


Page 3

Reference should be made to the appended engineering logs for a full description of subsurface

conditions at each location.

The ground water level was monitored in each borehole after being left open for a short period of

time and has been summarised in the following table:

Borehole (BH) Depth below (m)

1 3.3

2 2.8

3 Dry

It is noted that the ground water level may vary from the above due to seasonal and climatic

changes.

4 DISCUSSION

It is understood that the pipeline is to consist of a sewer and most likely to be open trenching with

potential for under boring.

Based on the results of this investigation, the material to be encountered will vary from Silty Clay to

Gravelly/Clayey Sand, Clayey Sandy Gravel and weathered Siltstone rock. Field assessment and

insitu strength tests indicate that there is an allowable bearing pressure of 100kPa available for the

proposed pipeline.

It is expected that excavation/boring will generally be achieved with conventional earthmoving

equipment (large excavators). However, it is noted that weathered Siltstone rock was encountered

at depths of 2.5 (BH3) and 4.2m (BH2). Past experience with our drill rig indicates that it can drill

through extremely weathered rock but refuses on moderate strength rock or better. It is noted that

refusal was encountered in BH2 at a depth of 9.3m which is short of the targeted depth of 11m. In

addition, it is noted that with weathered Ordovician rock (Siltstone/Sandstone), it can vary over short

distances and harder Sandstone seams maybe encountered in areas not directly investigated. As

such, the use of a ripper or pneumatic hammer may be required. If rock is encountered while under

boring, the use of rock coring bits may be required for the horizontal bores.

In regards to the stability of the excavations, with the variability between clay and sand along the

alignment, and the presence of groundwater at depths of 2.8 and 3.3 metres in 2 of the boreholes,

pending invert levels, instability of the excavations may be encountered particularly in cohesionless

sands and gravels. As such, shoring of trenches or casing of underbores is likely to be required.


Page 4

For excavations above the water table and in the weathered rock, it is expected that they will remain

stable in the near vertical in the short term (1 week). For longer term opening it may be necessary

to batter the walls back to 1:2 (H:V) with the top soil material being at 1:1 or even benched out. The

stability of the weathered rock can be dependent on the jointing/bedding of the rock should be

inspected by a Geotechnical Engineer during excavation.

It is recommended that plant equipment (i.e. trucks, excavators etc) and excavated material remain

at minimum of 1.5 metres away from the trench opening to ensure that no additional loading is

influencing the excavated trench walls which may increase the risk of trench instability or failure.

5 IMPORTANT NOTES ABOUT THIS REPORT

The results from this investigation relate to the specified sites labelled throughout this document,

and hence the information obtained may need to be extrapolated to the rest of the designated area.

While care has been taken throughout this investigation, soil conditions can vary between each

individual test site and at depths greater than that drilled during this investigation. Hence, if variations

from this report are found during excavations/construction then Geotechnical Testing Services

should be notified so it can be assessed and appropriate advice provided.

The soil colours provided in the bore logs attached may vary with soil moisture content and individual

interpretation, therefore colour alone should not be used to identify these soils.

Strength characteristics of soils often exhibit a large variation between wet and dry conditions. Soil

characteristics of a soil profile are given on the soil conditions at the time of the investigation.

6 DISCLAIMER

This investigation has been carried out in goodwill and under the instructions of Tomkinson. The

investigation has been undertaken with the care and skill of competent personnel as defined within

Geotechnical Testing Services quality system. It is not a comprehensive investigation but a guide to

the conditions throughout the designated area.

This document has been prepared for Tomkinson, and hence no responsibility or liability is being

accepted to any third party, where any part of the report is used in either isolation or without

consideration of the whole document. This document is not appropriate where there has been a

significant change in the project or either for the specific needs of the reader.


Page 5

Please, don’t hesitate to contact the undersigned, if you require any further information or

assistance.

Shane Hampton (BE (Hons)) MIEAust Principal Geotechnical Engineer Telephone: (03) 5441 4881 Mobile: 0437 496 215 Email: [email protected]


Page 6

APPENDIX

BH3

BH2

BH1

D

U

K

E

S

L

A

N

E

LA

N

E

DU

KE

S

GTS REF: 20C 1181

DATE: 08 OCT. 2020

GEOTECHNICAL INVESTIGATION

APPROXIMATE LOCATIONS

NOT TO SCALE

CLIENT: TOMKINSON

LOCATION: DUKES LANE,

STRATHFIELDSAYE

PROPOSED SEWER ALIGNMENT

Borehole no.

Sheet no.

PO Box 13, Strathdale 3550 Job no.

Ph (03) 54414881 Fax (03) 5441 5089

Client : Date:

Project : Logged by:

Location : Dukes Lane, Strathfieldsaye

Drill model : Gemco HS7 Slope 90 deg RL surface: Not measured

Hole diameter : 100mm Bearing - deg Datum : -

Gravelly Silty CLAY (CI), medium M Stplasticity, brown, pale brown, black, some fine sand

0.50

1.00 PP 1.0m = 250 kPa

1.50 PP 1.5m = 250 kPa

2.00

2300mmSilty CLAY (CI), medium plasticity, M VStdark grey mottled brown 2.50

3.00 PP 3.0m = 340 kPa

3200mmSilty CLAY (CI), medium plasticity, M S SWL 3.3mdark grey mottled brown PP 3.5m = 90 kPa

4.00Gravelly Silty CLAY (CI), medium M Splasticity, dark grey mottled brown, orange/brown

BH1 terminated at 4.5 metres 4.50

Gra

phic

log

Wat

er

Moi

stur

e co

nditi

on

Con

sist

ency

den

sity

, in

dex Structure, additional

observations

Met

hod

Sup

portNotes

Samples Tests

ENGINEERINGBOREHOLE LOG

1

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Proposed Sewer Alignment RC & MM

Material DescriptionDepth

(m)

Borehole no.

Sheet no.


Ph (03) 54414881 Fax (03) 5441 5089

Client : Date:





FILL: Clayey Sandy SILT (ML), M MD FILLbrown, low plasticity 200mmSilty CLAY (CI), medium plasticity, M Stbrown mottled pale brown, some fine sand 0.50

1.00 PP 1.0m = 210 kPa1100mm

Clayey SAND (SP), fine, orange/brown, M MDlow plasticity

1.50

1800mmClayey Sandy GRAVEL (GW), fine M MDto coarse, brown, orange/brown, 2.00low plasticity, fine sand

2.50

SWL 2.8m

3.00

3200mmSilty CLAY (CL), low plasticity, M Stpale grey

3.50

4.00 PP 4.0m = 210 kPa



(m)

Gra

phic

log

Wat

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Moi

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e co

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on

Con

sist

ency

den

sity

, in


observations


2

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Notes Samples

Tests Met

hod

Sup

port

Borehole no.

Sheet no.


Ph (03) 54414881 Fax (03) 5441 5089

Client : Date:





Silty CLAY (CL), low plasticity, M Stpale grey 4200mmSILTSTONE (XW), extremely M-D L - M Rock: low to mediumweathered, pale grey strength

4.50

5.00

5.50

6.00

6.50

7.00

7.50

8.00

2 of 3

20C 1181

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, in


observations

Notes Samples

Tests Met

hod

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(m)

Gra

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log

Wat

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Borehole no.

Sheet no.


Ph (03) 54414881 Fax (03) 5441 5089

Client : Date:





SILTSTONE (XW), extremely M-D L - M Rock: low to mediumweathered, pale grey strength

8.50

9.00

BH2 terminated at 9.3 metres By Refusal9.50

10.00

10.50

11.00

11.50

12.00

BOREHOLE LOG2

3 of 3

20C 1181

Tomkinson 8/10/2020

ENGINEERING



(m)

Gra

phic

log

Wat

er

Moi

stur

e co

nditi

on

Con

sist

ency

den

sity

, in


observations

Notes Samples

Tests Met

hod

Sup

port

Borehole no.

Sheet no.


Ph (03) 54414881 Fax (03) 5441 5089

Client : Date:





FILL: Clayey Sandy SILT (ML), 100mm M MD FILLbrown, low plasticityClayey SAND (SP), fine, orange/brown, M MDlow plasticity

0.50

1.00

1.50

1800mmGravelly SAND (SP), fine to M MD-medium, orange/brown, 2.00 Dfine to coarse gravel

2500mm 2.50SILTSTONE (XW), extremely D L Rock: Low strengthweathered, off white

3.00BH3 terminated at 3.0 metres

3.50

4.00

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DESCRIPTIVE TERMS BOREHOLE/EXCAVATION LOG

Classification Symbol & Soil Name Classification of material and its description is based on the Unified Classification System as referenced in AS1726 – 1993 Geotechnical Site Investigations, Appendix A. A summary of the more common terms is included within. Particle Size Descriptive Terms

Name Subdivision Size

Boulders >200mm

Cobbles 63 – 200mm

Gravel Coarse 20 – 63mm

Medium 6 – 20mm

Fine 2.36 – 6mm

Sand Coarse 0.6 – 2.36mm

Medium 200 – 600 micron

Fine 75 – 200 micron

Silt 2 – 75 micron

Clay < 2 micron

Consistency of Cohesive Soils

Term Undrained shear strength,

su (kPa)

Field Guide

Very Soft (VS)

<12 A finger can be pushed well into the soil with little effort

Soft (S)

12 – 25 A finger can be pushed into the soil to about 25mm depth

Firm (F)

25 – 50 The soil can be indented about 5mm with the thumb

Stiff (St)

50 – 100 The surface of the soil can be indented with the thumb

Very Stiff (VSt)

100 – 200 The surface of the soil can be indented by thumb nail

Hard (H)

>200 The surface of the soil can be marked only with the thumbnail

Friable (F)

- Crumbles or powders when scraped by thumbnail

Density of Granular Soils

Term Density Index (%)

Very Loose (VL) < 15

Loose (L) 15 – 35

Medium Dense (MD) 35 – 65

Dense (D) 65 – 85

Very Dense (VD) > 85

Minor Components

Term Field Guide Proportion of Minor Component In:

Trace of Presence just detectable by feel or eye

Coarse grained soils: <5% Fine grained soils: <15%

Some Presence easily detectable by feel or eye

Coarse grained soils: 5-12% Fine grained soils: 15-30%

Moisture Condition Dry (D) Looks & feels dry. Cohesive soils are usually

hard, powdery or friable. Granular soils run freely through the hand.

Moist (M) Soil feels cool and darkened in colour. Cohesive soils can be moulded. Granular soils tend to cohere. Free water does not form.

Wet (W) As for moist, but with free water forming on hands when remoulded.

Method S Auger Screwing D Auger Drilling R Roller/tricone

W Washboring N Natural Exposure E Existing Excavation

B Blade/bucket C Coring H Hammer Drill

Support * Nil C Casing M Mud/polymer

Water * Not observed Observed water level (date shown) Observed water inflow Observed water outflow R Refer to report for details Structures, Additional Observations PP Pocket Penetrometer test (kPa) DCP Dynamic Cone Penetrometer test (blows/100mm)

Notes, Samples, Tests U63 Undisturbed sample, 63mm diameter D Disturbed sample N* Standard Penetration Test, (*) Sample Figure = results Surface Known boundary - - - - - - - - - - Probably boundary -?-?-?-?-?-?- Possible boundary

Documents

Geotechnical investigation for Tomkinson · 2020. 11. 24. · sites south-eastern boundary. This was generally confirmed by the field data. 3 FIELDWORK The geotechnical investigation