Hydrogeological and Geotechnical Investigation · Table 5-2 Falling Head Test Permeability Table...

Hydrogeological and Geotechnical Investigation Inkpen Road Waste Management Facility Shire of Northam

TW17035-Inkpen Road Site Investigation_1a September 2017 |

Assets | Engineering | Environment | Noise | Spatial | Waste

Hydrogeological and Geotechnical Investigation

Inkpen Road Waste Management Facility

Prepared for Shire of Northam

September 2017

Project Number: TW17035


TW17035-Inkpen Road Site Investigation_1a September 2017 | Page i

DOCUMENT CONTROL

Version Description Date Author Reviewer

0a Internal Review 12/09/2017 JS FD

1a Released to Client 20/09/2017 JS FD

Approval for Release

Name Position File Reference

Fraser Daly Senior Geo-Environmental Consultant TW17035-Inkpen Road Site Investigation_1a

Signature

Copyright of this document or any part of this document remains with Talis Consultants Pty Ltd and cannot be used,

transferred or reproduced in any manner or form without prior written consent from Talis Consultants Pty Ltd.


TW17035-Inkpen Road Site Investigation_1a September 2017 | Page ii

Table of Contents 1 Introduction ............................................................................................................................................ 1

1.1 Objectives .............................................................................................................................................. 1

1.2 Scope of Work ....................................................................................................................................... 1

2 Background ............................................................................................................................................. 2

2.1 Location ................................................................................................................................................. 2

2.2 Zoning and Surrounding Land Use ........................................................................................................ 2

2.3 Environmental Attributes ...................................................................................................................... 2

2.3.1 Climate ................................................................................................................................... 2

2.3.2 Site Conditions ....................................................................................................................... 3

2.3.3 Topography ............................................................................................................................ 3

2.4 Geology ................................................................................................................................................. 3

2.4.1 Quaternary Geology ............................................................................................................... 3

2.4.2 Archean geology .................................................................................................................... 3

2.4.3 Structural Geology ................................................................................................................. 3

2.5 Hydrogeology ........................................................................................................................................ 3

2.5.1 Hydrogeology ......................................................................................................................... 3

2.5.2 Groundwater Use ................................................................................................................... 3

2.5.3 Hydrology ............................................................................................................................... 4

3 Project Methodology ............................................................................................................................... 5

3.1 Intrusive Investigation ........................................................................................................................... 5

3.2 Drilling Techniques ................................................................................................................................ 5

3.2.1 Soil Testing ............................................................................................................................. 5

4 Field Observations ................................................................................................................................... 6

4.1 Geology ................................................................................................................................................. 6

4.2 Groundwater Well Construction Details ............................................................................................... 7

4.3 Survey Data ........................................................................................................................................... 8


TW17035-Inkpen Road Site Investigation_1a September 2017 | Page iii

4.4 Groundwater Depth and Flow Direction ............................................................................................... 8

5 Geotechnical Laboratory Results and Assessment ................................................................................... 9

5.1 Soil Index Testing .................................................................................................................................. 9

5.2 Permeability .......................................................................................................................................... 9

6 Conceptual Site Model .......................................................................................................................... 10

6.1 Contamination Source ........................................................................................................................ 10

6.2 Contaminants of Potential Concern .................................................................................................... 10

6.3 Receptors ............................................................................................................................................ 10

6.4 Transportation Mechanisms ............................................................................................................... 10

6.5 Exposure Pathways and Qualitative Risk Assessment ........................................................................ 11

7 Discussion ............................................................................................................................................. 13

8 Conclusions and Recommendations ...................................................................................................... 14

References ..................................................................................................................................................... 15

Figures ........................................................................................................................................................... 16

Tables Table 4-1: Groundwater Well Construction Details

Table 4-2: Groundwater Well Survey Details

Table 5-1: Soil Index

Table 5-2 Falling Head Test Permeability

Table 6-1 Risk Assessment

Figures Figure 1: Locality

Figure 2: Site Aerial

Figure 3: Zoning

Figure 4: Topography


TW17035-Inkpen Road Site Investigation_1a September 2017 | Page iv

Figure 5: Quaternary Geology

Figure 6: Archean Geology

Figure 7: Hydrogeology

Figure 8: Hydrology

Figure 9: Bore Locations

Appendices : Bore Logs

: Photographs

: Laboratory Certificates

: Survey Data


TW17035-Inkpen Road Site Investigation_1a September 2017 | Page 1

1 Introduction

Talis Consultants Pty Ltd (Talis) was engaged by the Shire of Northam (the Shire) to undertake a Works Approval

and Licence Application for a Category 64 Class II Putrescible Landfill and a Category 62 Solid Waste Depot at its

Inkpen Road Waste Management Facility. As part of the Works Approval, a site investigation targeting the

hydrogeological regime and the geotechnical properties of the underlying soils was undertaken to support the

future development of the Site, while allowing for the assessment of potential impacts to groundwater.

This report forms part of the overall works approval document (TW17035 – Northam EAMP.1a-Environmental

Assessment Management Plan, Inkpen Road Waste Management Facility, Talis, 2017), and should be read in

conjunction with this documentation.

1.1 Objectives

The objective of the Site investigation were to:

Understand the groundwater regime across the Site;

Understand the engineering properties of the subsoils, principally their permeability; and

Understand the potential implications to the surrounding environment and groundwater users.

1.2 Scope of Work

To achieve the objectives described above, the Site investigation included:

The installation of three groundwater monitoring wells targeting the regional aquifer;

Geotechnical/geological assessment of the underlying soil and stratum;

Geotechnical testing of targeted soil sampling; and

Hydrogeological and Geotechnical reporting.



2 Background

2.1 Location

The Site is located at Lot 28734, Reserve R25796 Inkpen Road, Copley, WA 6562, located within the Kwolyinine

Nature Reserve. The Site covers an area of approximately 15 hectares (ha) and is located 3 km south east of the

town of Wundowie within the Shire, and approximately 54 km to the east of Perth’s Central Business District

(CBD). The Site location is presented in Figure 1 and Figure 2.

2.2 Zoning and Surrounding Land Use

Under the Shire of Northam Local Planning Scheme No. 6 (District Scheme), the Site is zoned as 'Public Purpose-

Rubbish Disposal', with the surrounding areas zoned as a Local Reserve, more specifically a 'Conservation of Flora

and Fauna' area. This corresponds to the Kwolyinine Nature Reserve, see Figure 3.

2.3 Environmental Attributes

2.3.1 Climate

The Site is located within a region that experiences a Hot Mediterranean climate, with warm dry summers and

cool wet winters. The closest weather station to the Site, that has recorded longer term weather conditions, was

the facility located at Bakers Hill. However, this facility only presented data up until 1985. Therefore, in order to

provide a more current and robust data set, the facility located within Northam was used. The monthly averages

for both temperature and rainfall are presented in the following graph.

Graph 1: Climatic Data

Bureau of Meteorology (BoM) website (2017). The above data was recorded at Northam weather station (1902 to 2017 for temperature,

1877 to 2017 for rainfall).

0

10

20

30

40

50

60

70

80

90

0

5

10

15

20

25

30

35

40

mm

Deg

rees

Cel

siu

s

Climatic Data

Mean Maximum Temperature Mean Minimum Temperature Mean Rainfall



An assessment of the meteorological conditions has shown the summer months of January and February to be

the warmest and driest, while the winter months of July and August were shown to be the coldest and wettest

period.

2.3.2 Site Conditions

The Site is currently used as a Class II waste management facility with associated infrastructure. The central Site

area is occupied by the main landfilling cell, with several stockpiles noted within the northern portion of the Site,

likely associated with waste stockpiles. Access tracks associated with the facility dissect the Site, with all roads

being unsealed. Large trees generally flank the perimeter of the Site.

2.3.3 Topography

The Australian Government National Map (http://nationalmap.gov.au/) dataset on a 1:250,000 scale shows that

the Site and surrounds are relatively flat, sitting at approximately 300 m Australian Height Datum (AHD).

Crossland & Hardy Pty Ltd undertook a topographical survey of the Site in August 2016. The survey data showed

that the highest elevation is located in the south east corner of the Site, which reaches approximately 318 m

AHD. The Site slopes down from this point to the north western corner of the Site which sits at approximately

295 m AHD. The topographical data is presented in Figure 4.

2.4 Geology

2.4.1 Quaternary Geology

The Department of Mines, Industry Regulation and Safety (DMIRS), previously known as the Department of

Mines and Petroleum (DMP), GeoView Atlas (https://geoview.dmp.wa.gov.au/GeoViews/?Viewer=GeoVIEW)

highlighted the underlying regolith soils to be “residual or relict material, including ferruginous, siliceous and

calcareous duricrust”. The underlying regolith/superficial soils are presented in Figure 5.

2.4.2 Archean geology

The DMIRS GeoView Atlas described the underlying hard rock geology as “South West Terrane Greenstones”,

forming part of the Yilgarn Craton. It is likely to consist of high grade metamorphic granulites and migmatites.

The underlying hard rock geology is presented on Figure 6.

2.4.3 Structural Geology

No major linear structure were identified within the confines of the Site, or the immediate surround area. No

information has been sourced on the dip or strike of the underlying lithologies.

2.5 Hydrogeology

2.5.1 Hydrogeology

Hydrogeological data is limited for the Site and its surrounds. The Australian Government National Map

(http://nationalmap.gov.au/) identifies that groundwater in the region flows through fractured rocks, see Figure

7.

2.5.2 Groundwater Use

The Department of Water (DoW) Water Information Reporting (WIR) Portal

(http://wir.water.wa.gov.au/Pages/Water-Information-Reporting.aspx) highlighted six registered bores to be



located within a 2 km radius of the Site, see Figure 7. Of these, four were noted to be wells, while the remaining

two were noted as surface water sampling locations associated with Weerrirbee Brook (Wundowie Foundry)

and Coates Gully (DoW). Outside of the 2 km radius, numerous bores exist, likely associated with the agricultural

nature of the surrounding area. Users of any groundwater within this area will likely be in a non-potable,

irrigation and/or livestock setting. However, The Australian Government National Map

(http://nationalmap.gov.au/) highlighted that the underlying groundwater would likely be saline in nature, with

a salinity value >3,000 mg/L. A salinity value in this region would limit the beneficial use of any groundwater in

the area.

2.5.3 Hydrology

The Site is located within the Swan River Surface Water Proclaimed Area. No surface water bodies were noticed

within the confines of the Site. The closest surface waterbody is the Coates Gully which flows north, east and

west of the Site, with its closest part approximately 1.2 km to the west of the Site, see Figure 8. Beyond this,

they are numerous dams associated with agriculture within a 2 km radius of the Site.



3 Project Methodology

3.1 Intrusive Investigation

The intrusive investigation was undertaken between 8-10 August 2017, and consisted of the following:

Sinking of three soil bores to a maximum 42 m depth below ground level (bgl) for geotechnical

purposes;

Conversion of the three soil bores into groundwater monitoring wells; and

Collection of representative soil samples from appropriate horizons as part of the geotechnical

investigation.

3.2 Drilling Techniques

All bores were sunk using a Hanjin D8 drilling rig utilising Rotary Air drilling methods through superficial soils,

and 3 inch downhole hammer through bedrock. This drilling method, which is a semi-destructive drilling method,

allowed for the broad assessment of the subsoil and underlying rock, and the collection of disturbed bulk soil

samples.

All field work, including the logging of the subsurface profiles and collection of soil samples, were undertaken

by an experienced geo-environmental engineer from Talis. The soil profile was logged in accordance with the

following standard:

Australian Standard (AS) 1726:1999-Geotechnical Site Investigation.

The subsurface conditions are summarised in Section 4.1.

3.2.1 Soil Testing

To assess the subsoil conditions, laboratory analysis on selected disturbed samples recovered during the

fieldwork was undertaken. This comprised of the following testing:

AS 1289.3.6.1, Soil Classification test- Determination of the particle size distribution of a soil-Standard

method of analysis by sieving;

AS 1289.3.6.3, Soil Classification test- Determination of the particle size distribution of a soil-Standard

method of fine analysis using hydrometer; and

AS1289.6.7.2, Soil Strength and consolidation testing-Determination of the permeability of a soil-Falling

head method for a remoulded specimen.



4 Field Observations

The three soil bores were sunk to assess underlying geological profile and hydrogeological conditions beneath

the Site. The following section described the subsurface conditions, while Appendix A presents the engineering

logs with photographs presented in Appendix B. The Geotechnical laboratory results certificates are presented

in Appendix C. Their locations are presented in Figure 9.

4.1 Geology

The general underlying geology encountered during the sinking of the geotechnical bores/groundwater wells

can be summarised as follows:

GW01

Silty/sandy GRAVEL at the surface described as subangular to subrounded, poorly graded, iron lateritic

pisoliths with fine grained sand inclusions to 4 m bgl; underlain by

Clayey SILT, low plasticity and orange, beige, brown and red in colour. This horizon was encountered to

a depth of 24 m bgl; underlain by

Gravelly silty SAND, fine to coarse grained, subangular to subrounded, well graded and orange-beige in

colour. This horizon was encountered to a depth of 25 m bgl; underlain by

Sandy SILT with trace clay described as having a low plasticity. The sand was described as fine grained,

subangular to subrounded, poorly graded and brown in colour. This horizon was encountered to a

depth of 28 m bgl; underlain by

GRANITE, expressed as clayey SILT with trace sand, fine to coarse grained, subangular to subrounded

and brown and green in colour. Trace siltstone at depth.

GW02

Silty/sandy GRAVEL at the surface, described as subangular to subrounded, poorly to well graded, iron

rich siltstone. The sand proportion was described a fine grained, subangular to subrounded and orange

to red in colour, to 3.5 m bgl; underlain by

Gravelly/silty SAND, fine to coarse grained, subangular to subrounded, poorly to well graded and beige

to orange in colour. This was encountered to a depth of 6.5 m bgl; underlain by

Clayey SILT described as having a low plasticity and white in colour. This horizon was encountered to a

depth of 8.5 m bgl; underlain by

Silty SAND and sandy SILT layers. The sand was described as fine grained, subangular to subrounded,

beige and orange and brown in colour. It was encountered to a depth of 11.5 m bgl; underlain by

SILT with trace sand. The sand proportion was described as fine grained, subangular to subrounded and

white to grey in colour. This horizon was encountered to a depth of 18 m bgl; underlain by

GRANITE, expressed as silt to coarse grained sand, subangular to subrounded, well graded. Coarse

grained fragments are poorly cemented and beige to light brown in colour. This was encountered to a

depth of 35 m bgl.

GW03

Sandy GRAVEL and gravelly SAND at surface to a depth of 3 m bgl. This was described as fine to coarse

grained, subangular to subrounded, iron rich lateritic pisoliths and orange-brown in colour; underlain

by



Clayey SAND. The sand proportion was described as fine to medium grained, subangular to subrounded,

gap graded. The clay proportion exhibited a low plasticity. Orange to beige in colour, to 4 m bgl;

underlain by

Clayey SILT described as having a low plasticity and beige to orange in colour. This horizon was

encountered to 4.5 m bgl; underlain by

Clayey silty SAND, fine to medium grained, subangular to subrounded, gap graded. Clay, low plasticity

and beige to orange in colour, to 5.5 m bgl; underlain by

Gravelly SAND, fine to coarse grained, angular to subrounded, well graded, iron rich lateritic pisoliths

and red to beige in colour, to 9 m bgl; underlain by

Clayey silty SAND and silty SAND interlayers, fine to coarse grained, subangular to subrounded, poorly

to well graded. The clay was described as having a low plasticity. Orange, white and brown in colour

and encountered to a depth of 16.5 m bgl; underlain by

Clayey SILT, low plasticity and red, orange and brown in colour. Encountered to a depth of 21 m bgl;

underlain by

Clayey silty SAND, further underlain by clayey SILT. The sand was described as fine to coarse grained,

subangular to subrounded, well graded. The cohesive material was described as having a low plasticity.

Red to brown in colour and encountered to a depth of to 24 m bgl; underlain by

Silty CLAY, low plasticity, orange to brown in colour and encountered to 25.2 m bgl; underlain by

GRANITE, presenting itself as silty SAND, silt to coarse grained with trace clay nodules. Interlocked

coarse crystals of quartz and feldspar and pyroxene and light grey in colour, to 35 m bgl.

4.2 Groundwater Well Construction Details

The three new groundwater monitoring wells were installed in accordance with the following standard:

ASTM D5092-04 Standard Practice for Design and Installation of Groundwater Monitoring Wells.

The construction details for the three groundwater wells installed by Soil Mechanics are provided in Table 4-1

below, with construction logs provided in Appendix A, with their location shown in Figure 9.

Table 4-1: Groundwater Well Construction Details

Well ID GW01 GW02 GW03

Installation date 08/08/2017 09/08/2017 10/08/2017

Well Depth 41.7 m 35 m

Bore/casing diameter 100 mm hole/ 50mm Class 18 PVC

Screen/casing construction

Screen length 6 m

Filter pack 3.2 mm washed silica placed

to 3.8 m above the screen

3.2 mm washed silica placed to 1.0 m

above the screen

Casing seal 1 m bentonite overlaying the washed silica

Well cover Up-rise lockable steel monument cover



4.3 Survey Data

The three groundwater wells were surveyed by Handley Surveys on 18 August 2017. The Top of Casing (ToC) and

ground level at each location was surveyed to AHD, with details summarised in Table 4-2, with survey data

provided in Appendix D.

Table 4-2: Groundwater Well Survey Details

Well ID GW01 GW02 GW03

Northings 6483451.336 6483076.909 6483068.351

Eastings 443908.597 443915.993 444215.681

ToC RL (m AHD) 299.993 310.907 317.402

Ground level RL (m AHD) 299.345 310.316 316.833

4.4 Groundwater Depth and Flow Direction

Groundwater was not intercepted during the sinking of the three soil bores, or subsequent gauging by Talis.

Consequently, a groundwater assessment was not undertaken as part of this investigation.



5 Geotechnical Laboratory Results and Assessment

Laboratory testing on soil samples was undertaken by E.Precision laboratories in their National Association of

Testing Authorities (NATA) accredited laboratory and consisted of the testing detailed in Section 3.

The laboratory test results, along with the test methods followed are presented in Appendix C, while results are

summarised in the following sections.

5.1 Soil Index Testing

PSD analysis results are summarised in Table 5-1 below.

Table 5-1: Soil Index

Location Depth (m

bgl) % Gravel

% Coarse

Grained

Sand

% Medium

Grained

Sand

% Fine

Grained

Sand

% Silt % Clay

GW01 8.0 m 1.8 14.9 34.8 21 19 8.5

GW02 12.0 m 0.2 3.51 22.3 12.8 52.2 9

GW03 10.0 m 0.0 1.5 6.5 10.6 73.9 7.5

Soil indexing generally confirmed the visual assessment, confirming the presence of sandy SILT with clay at GW02

and SILT with sand at GW03. Soil indexing at GW01 highlighted a higher percentage of sand, describing the

material as a silty SAND with clay instead of the SILT with clay.

5.2 Permeability

The falling head tests were scheduled on targeted horizons to ascertain the permeability of the underlying soils.

The outcome of this assessment is presented in Table 5-2 below.

Table 5-2 Falling Head Test Permeability

Sample ID GW01 GW02 GW03

Sample Depth 8.0 m 10.0 m 10.0 m 12.0 m 10.0 m 12.0 m

Permeability (m/s) 4.452x10-7 4.78x10-8 3.009x10-7 2.59x10-8 1.05x10-8 3.18x10-8

As shown in Table 5-2 above, the permeability was shown to range between 4.452 x 10-7 m/s and 1.05 x 10-8 m/s.

Permeability was shown to be related to the soil index, the higher permeability linked to the higher proportion

of sand. Permeability was also shown to decrease with depth at GW01 and GW02.



6 Conceptual Site Model

In general accordance with the National Environment Protection (Assessment of Contamination) Measure

(NEPM, 2013), a tier 1 preliminary conceptual site mode (CSM) in relation to the risk to the potential

groundwater resource has been prepared for the Site. This combines the information from the investigation

undertaken and a literature review. This CSM identifies potential contamination sources, exposure,

transportation pathways and receptors that may exists within the vicinity of the Site.

6.1 Contamination Source

The source of contamination at the Site is the landfilled waste.

6.2 Contaminants of Potential Concern

Contaminants of potential concern (COPCs) that may be associated with landfilling vary depending on the buried

waste. The Department of Environment Regulation (DER) Assessment and management of contaminated sites

(DER, 2014) guidelines lists the following COPCs to associated with landfill sites:

PCBs;

Alkanes;

Sulfides;

Metals;

Organic Acids;

Nutrients (i.e. nitrogen, phosphorous);

Total Recoverable Hydrocarbons (TRH);

Polycyclic Aromatic Hydrocarbons (PAH);

Ammonia;

Total Dissolved Solids (TDS);

Benzene, toluene, ethylbenzene and xylenes (BTEX); and

Phenols.

6.3 Receptors

The following receptors have been identified:

Onsite – workers and visitors;

Onsite – groundwater resource;

Onsite – flora and visiting fauna;

Offsite – groundwater users down-hydraulic gradient;

Offsite – surface water users where groundwater from beneath the Site recharges to a surface water

body; and

Offsite – sensitive ecological receptors.

6.4 Transportation Mechanisms

Exposure pathways are means by which COPCs impact receptors. Exposure pathways for groundwater include:

Abstraction of groundwater;

Dermal contact;



Ingestion;

Inhalation;

Movement down-hydraulic gradient; and

Uptake by groundwater dependent ecosystems.

6.5 Exposure Pathways and Qualitative Risk Assessment

Table 6-1 below identifies the receptor-exposure-pathways in relation to groundwater that may exist at the Site.

The level or risk has been determined by combining the consequence and the likelihood using the definitions

presented in AS310000:2009 Risk Management-Principles and Guidelines.

Table 6-1 Risk Assessment

Receptor Exposure Pathway

Pathway Complete/

Partially Complete/

Incomplete

Reasoning Risk

Site workers

and visitors to

the Site

Dermal Contact or

accidental inhalation

or ingestion of

groundwater

Incomplete

Groundwater is not abstracted

at the Site, therefore this

exposure pathway is

incomplete.

Low

Flora and

visiting Fauna

Absorption of

groundwater by flora,

dermal contact or

ingestion by fauna

Incomplete

Groundwater was not

intercepted during the

investigation. Due to the depth

to groundwater, there will be no

direct contact with deep rooted

flora and subsequent fauna

ingestion of potentially

impacted flora. The tree root

zone is anticipated to be located

within the shallow gravel layer,

which will be subject to

interactions via rain water

infiltration and not absorption

from the underlying

groundwater.

Low

Groundwater

users down

hydraulic

gradient

Dermal contact or

accidental inhalation

and ingestion of

groundwater

Incomplete

Groundwater was not

intercepted during the

investigation. Considering the

separation distance, coupled

with the relatively low

permeability of the underlying

soils, it is considered that the

risk to the groundwater

resource is low. Additionally,

there are no registered

groundwater wells within the

direct vicinity of the Site (<1km),

further reducing the risk to

Low



Receptor Exposure Pathway

Pathway Complete/

Partially Complete/

Incomplete

Reasoning Risk

potential down-hydraulic users

of groundwater.

Surface water

users and

ecological

receptors.

Groundwater and

surface water

interactions

Incomplete

No surface water bodies were

noted within the confines of the

Site. The closest significant

water body is the Coates Gully,

located approximately 1.2 km to

the west of the Site. Given the

distance and depth to any

potential groundwater, it is

considered that surface water

and groundwater interactions

will be limited, resulting in a low

risk to sensitive receptors.

Low



7 Discussion

The Site comprises an area of approximately 15 ha and is located at Lot 28734, Reserve R25796 Inkpen Road,

Copley, WA, within the Kwolyinine Nature Reserve, approximately 54 km to the east of Perth CBD. The Site is

an operational landfill, owned and operated by the Shire, whom are seeking approval to expand the facility to

include a Category 64 Class II Putrescible Landfill and Category 62, Solid Waste Depot.

Scope of Work

The hydrogeological and geotechnical investigation was undertaken in order to facilitate the above, as part of

the Works Approval. The investigation involved the sinking of three soil bores strategically located across the

Site, to a maximum depth of 42 m bgl. These bores were subsequently converted into groundwater monitoring

wells.

Soil Conditions

During the sinking of the soil bores, the initial soil profile encountered generally consisted of coarse grained

materials described as silty/sandy GRAVELs from the surface to 4 m bgl, further underlain by gravelly silty SAND.

Beneath these horizons, the soils were described as clayey SILT material with sand inclusions, likely representing

residual soils/extremely weathered bedrock. Bedrock was encountered within all bores at a depth of between

18 m bgl (GW02) and 30 m bgl (GW01), and was described as GRANITE.

Failing head permeability tests were conducted on targeted soil samples, with consideration to the current

landfill design and any future construction. This assessment was undertaken at depths of between 8.0 m bgl and

12 m bgl and suggested that the permeabilities were relatively low, varying between 4.452 x 10-7 m/s and 1.05

x 10-8 m/s, with permeability generally decreasing with depth.

Groundwater

In terms of beneficial use of groundwater in the area, four registered groundwater wells were shown to be

located within a 2 km radius of the Site. It is anticipated that these bores may be used in a non-potable, irrigation

or agricultural setting.

Following installation of the groundwater wells, a gauging event failed to encounter groundwater beneath the

Site. It is anticipated however, that a regional groundwater would exist at a greater depth within the granite

bedrock. Fractured rock aquifer such as this generally have a low yield and are of limited beneficial use due to

relatively high salinity, as suggested by the Australian Government National Map.

Risk Assessment

In terms of risk to groundwater users, it was considered that the risk is low, due to the separation distance (>1

km from the Site) to any potential groundwater user, the deep groundwater table (>42 m bgl) and low

permeability of the soils encountered at the Site. Additionally, no surface water bodies were located within the

vicinity of the Site (<1 km), with the nearest identified significant surface water body being the Coates Gully,

located approximately 1.2 km to the west.



8 Conclusions and Recommendations

Based on the investigation undertaken, Talis has drawn the following conclusions:

The Site is currently an operational landfill, with the Shire anticipating future development of the Site

to include the construction of a Category 64 Class II Putrescible Landfill Cell and a Category 62 Solid

Waste Depot;

A total of three soil bores were sunk to a maximum 42 m depth for the purposes of geotechnically

assessing the underlying soils and bedrock;

All soil bores were converted into three groundwater monitoring wells for the purposes of a

hydrogeological assessment;

The near surface soils generally comprised of silty/sandy GRAVEL to a depth of 4 m bgl;

Underlying the gravel material, the profile included interbedded clayey, silty and sandy material to a

depth of between 18 m bgl and 30 m bgl;

The underlying bedrock was described as GRANITE;

Permeability assessments undertaken at depths of between 8.0 m bgl and 12 m bgl suggested that the

permeabilities were relatively low, varying between 4.452 x 10-7 m/s and 1.05 x 10-8 m/s, with

permeability generally decreasing with depth; and

Groundwater was not encountered at any of the three locations, though is anticipated to exist at a

greater depth within the granite bedrock;

Overall, there appears to be a low risk to sensitive receptors associated with the Sites operation as a landfill.

This is based on the Site’s location, being >1 km from possible sensitive receptors from a hydrogeological

perspective, the low permeability of the underlying soils and the groundwater table sitting >42 m bgl. In addition,

the construction of the new landfill cell will include modern engineering practices, therefore further reducing

the potential impacts to groundwater.



References Australian Government National Map, http://nationalmap.gov.au/

Australian Standard (AS) 1726:1999-Geotechnical Site Investigation

AS 1289.3.6.1, Soil Classification test- Determination of the particle size distribution of a soil-Standard method

of analysis by sieving

AS 1289.3.6.3, Soil Classification test- Determination of the particle size distribution of a soil-Standard method

of fine analysis using hydrometer

AS1289.6.7.2, Soil Strength and consolidation testing-Determination of the permeability of a soil-Falling head

method for a remoulded specimen

Bureau of Meteorology, http://www.bom.gov.au/wa/?ref=hdr

Department of Mines, Industry Regulation and Safety (DMIRS) GeoView Atlas

https://geoview.dmp.wa.gov.au/GeoViews/?Viewer=GeoVIEW

Department of Environment and Regulation, Assessment and management of contaminated sites, 2014

Department of Water and Environmental Regulation, Water Information Reporting Portal

http://wir.water.wa.gov.au/Pages/Water-Information-Reporting.aspx

National Environment Protection (Assessment of Contamination) Measure, 2013



Figures Figure 1: Locality

Figure 2: Site Aerial

Figure 3: Zoning

Figure 4: Topography

Figure 5: Quaternary Geology

Figure 6: Archean Geology

Figure 7: Hydrogeology

Figure 8: Hydrology

Figure 9: Bore Locations

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Douglas Rd

Inkpen Rd

Grea

t East

ernHw

y

W U N D O W I E

440,000

440,000

441,000

441,000

442,000

442,000

443,000

443,000

444,000

444,000

445,000

445,000

446,000

446,000

447,000

447,000

448,000

448,000

6,480

,000

6,480

,000

6,481

,000

6,481

,000

6,482

,000

6,482

,000

6,483

,000

6,483

,000

6,484

,000

6,484

,000

6,485

,000

6,485

,000

6,486

,000

6,486

,000

6,487

,000

6,487

,000

LEGEND

© Talis Consultants Pty Ltd ("Talis") Copyright in the drawings, information and datarecorded in this document ("the information") is the property of Talis. This document andthe information are soley for the use of the authorised recipient andthis document may not be used, transferred or reproduced in whole or partfor any purpose other than that which it is supplied by Talis withoutwritten consent. Talis makes no representation, undertakes no duty andaccepts no responsibility to any third party who may use or rely upon thisdocument or the information.

NorthamBakers Hill

WundowieChidlow YorkPerth

Armadale

Rockingham

Mandurah

0 20 40 60 80 100 120 14010km

LOCALITY

LOCALITY PLANInkpen Road WMF

Northam, WA

0 300 600 900 1,200150metres

¤ Coordinate System: GDA 1994 MGA Zone 50Projection: Transverse Mercator, Datum: GDA 1994

Reviewed:Checked:Prepared: F Walker Date: 12/09/2017

Revision:

Scale @ A3:1:30,000

Project No:TW17035A

Figure

01

Site Boundary

P PO Box 454, Leederville WA 6903 | A Level 1 660 Newcastle St, Leederville WA 6007 | T 1300 251 070 | W www.talisconsultants.com.au

N KingC Pelletier

Data Source: Imagery: Nearmap, 2017. Site Boundary: Cadastre, 2016.

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Inkpen Rd

444,000

444,000

6,483

,000

6,483

,000

LEGEND


NorthamBakers Hill


Armadale

Rockingham

Mandurah

0 20 40 60 80 100 120 14010km

LOCALITY

AERIAL PLANInkpen Road WMF

Northam, WA

0 25 50 75 10012.5metres



Revision:

Scale @ A3:1:2,500

Project No:TW17035A

Figure

02

Site Boundary


N KingC Pelletier

Data Source: Imagery: Landgate, 2017. Site Boundary: Cadastre, 2016.

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W U N D O W I E441,000

441,000

442,000

442,000

443,000

443,000

444,000

444,000

445,000

445,000

446,000

446,000

447,000

447,000

6,481

,000

6,481

,000

6,482

,000

6,482

,000

6,483

,000

6,483

,000

6,484

,000

6,484

,000

6,485

,000

6,485

,000

LEGEND


NorthamBakers Hill


Armadale

Rockingham

Mandurah

0 20 40 60 80 100 120 14010km

LOCALITY

ZONINGInkpen Road WMF

Northam, WA

0 200 400 600 800100metres



Revision:

Scale @ A3:1:20,000

Project No:TW17035A

Figure

03

Site BoundaryZoning

Conservation of flora andfaunaLight and Service IndustryPublic PurposesRegional RoadRuralRural Residential


N KingC Pelletier


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307

315.5

298

310

307 312

298.5

309.5

297

296

303.5

299.5

303.5

301

318

302

303

311303

303

304

314

304

311

308

300

308

305

306

308

309

299

297

307

298

296

312

295

305

313

305

305.5

305

298

309.5

296.5

299.5

308

314.5314.5313

300

307

312.5

298

317.5

297.5

296

312.5

311

306.5298

296.5

315

299301

302.5

303

309

314.5314.5

298

308.5

317

296.5

312.5

312.5

304.5

314

300.5

296

299.5

295.5

303.5

310

314

316.5

309

300298.5

309.5

316

303

304.5

314.5

313.5

305

315

315.5

296.5

304

313

309

315

314.5

305

308.5

314.5

306.5

306 307

313.5

306.5

303.5

295.5

296.5

298.5 299.5297.5

303.5

300.5

301.5

304.5

313.5

302.5

306.5

310.5

312.5

307.5

305.5

307.5

309.5

311.5

308.5

444,000

444,000

LEGEND


NorthamBakers Hill


Armadale

Rockingham

Mandurah

0 20 40 60 80 100 120 14010km

LOCALITY

TOPOGRAPHYInkpen Road WMF

Northam, WA

0 20 40 60 8010metres



Revision:

Scale @ A3:1:2,031

Project No:TW17035A

Figure

0 4

Site BoundaryElevation Contours (mAHD)


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R e s i d u a l

E x p o s e d

C o l l u v i u m

441,000

441,000

442,000

442,000

443,000

443,000

444,000

444,000

445,000

445,000

446,000

446,000

447,000

447,000

6,481

,000

6,481

,000

6,482

,000

6,482

,000

6,483

,000

6,483

,000

6,484

,000

6,484

,000

6,485

,000

6,485

,000

6,486

,000

6,486

,000

LEGEND


NorthamBakers Hill


Armadale

Rockingham

Mandurah

0 20 40 60 80 100 120 14010km

LOCALITY

QUATERNARYGEOLOGY

Inkpen Road WMFNortham, WA

0 200 400 600 800100metres



Revision:

Scale @ A3:1:20,000

Project No:TW17035A

Figure

05

Site Boundary1:500 000 State regolith (GSWA)

Exposed rock, saprolite, andsaprockResidual or relict material,including ferruginous,siliceous, and calcareousduricrustSlope deposits, includingcolluvium and sheetwash


N KingC Pelletier


Hydrogeological and Geotechnical Investigation · Table 5-2 Falling Head Test Permeability Table...

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Transcript of Hydrogeological and Geotechnical Investigation · Table 5-2 Falling Head Test Permeability Table...