Integrating Groundwater into the Urban Water Cycle · Urban Design: Draft Issues report (Ecological Engineering, 2006). 2.5 Further Consultation with Experts Discussions were held

Integrating Groundwater into the Urban Water Cycle

FINAL REPORT: SMART WATER FUND PROJECT 42M-2067

Final v3 26 September 2007

The SKM logo is a trade mark of Sinclair Knight Merz Pty Ltd. © Sinclair Knight Merz Pty Ltd, 2006

Integrating Groundwater into the Urban Water Cycle

FINAL REPORT: SMART WATER FUND PROJECT 42M-2067 Final v3 26 September 2007

Sinclair Knight Merz ABN 37 001 024 095 590 Orrong Road, Armadale 3143 PO Box 2500 Malvern VIC 3144 Australia Tel: +61 3 9248 3100 Fax: +61 3 9248 3364 Web: www.skmconsulting.com COPYRIGHT: The concepts and information contained in this document are the property of Sinclair Knight Merz Pty Ltd. Use or copying of this document in whole or in part without the written permission of Sinclair Knight Merz constitutes an infringement of copyright.

LIMITATION: This report has been prepared on behalf of and for the exclusive use of Sinclair Knight Merz Pty Ltd’s Client, and is subject to and issued in connection with the provisions of the agreement between Sinclair Knight Merz and its Client. Sinclair Knight Merz accepts no liability or responsibility whatsoever for or in respect of any use of or reliance upon this report by any third party.

Final Report: Integrating Groundwater into the Urban Water Cycle

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Contents

1. Introduction 1 1.1 Overview 1 1.1.1 Project Rationale 1 1.1.2 Project Objectives 2 1.2 Report Objectives 2

2. Relevant Investigations and Data Sets 3 2.1 Data Sets and Geological Information Sources 3 2.2 South East Water Limited 3 2.3 Private Landholders 3 2.4 Draft Reports for Cranbourne West Development 3 2.5 Further Consultation with Experts 3

3. Cranbourne West: Desktop Study of the Catchment Setting 4 3.1 Overview 4 3.2 Groundwater Management Area 4 3.3 Summary of Geological Units 7 3.3.1 Quaternary Swamp Deposits 8 3.3.2 Quaternary Dunes 8 3.3.3 Baxter Sandstone 8 3.3.4 Older Volcanics 8 3.3.5 Silurian basement 8 3.3.6 Lower Tertiary geological layers 8 3.4 Hydrogeology 9 3.4.1 Groundwater Flow Systems 9 3.4.2 Frankston Groundwater Management Area 9 3.4.3 State Observation Bore Network: Waterlevel Monitoring 10 3.5 Observed Groundwater Levels 11 3.6 Groundwater Salinity 14

4. Field Investigations 15 4.1 Description of Measurements 14/12/06 15 4.2 Field Investigations May 2007 16 4.2.1 Overview 16 4.2.2 Groundwater Bore Construction 16 4.3 Groundwater Sampling and Hydraulic Testing 17

5. Field Data Analysis 18 5.1 New Groundwater Observation Bores 18


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5.2 Hydraulic Testing of Aquifers 22 5.3 Groundwater Chemistry 23

6. Data Interpretation 28 6.1 Overview 28 6.2 Depth to Watertable 28 6.3 Groundwater Salinity 30 6.4 Geological Cross-Sections 31 6.5 Conceptual Model of the Groundwater System 35 6.6 Depth to watertable analysis – SW Cranbourne West 38

7. Conclusions 43 7.1 Overview 43 7.2 Estimate of Sustainable Groundwater Yield 43 7.3 Water Quality Analysis and Potential Use of Groundwater 44 7.4 Groundwater Constraints to Urban Development 45 7.5 Shallow Watertables: Threats, Causes and Management Options at Cranbourne West 52 7.6 Meeting Smart Water Fund Objectives 53

8. Ongoing Monitoring and Future Investigations 55 8.1 Ongoing Groundwater Monitoring 55 8.2 Future Groundwater Investigations 55

9. References 57

Appendix A Bore Logs of Geological Strata 58

Appendix B Analysis of Aquifer ‘Slug Tests’ 59

Appendix C Groundwater Beneficial Use Categories 60

Appendix D Submission to Cranbourne West Draft Precinct Plan 62


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1. Introduction

1.1 Overview The intended work program for this ‘Smart Water Fund’ project was described in Milestone 1. The introduction to the work program provides important context to the project as a whole and is repeated below.

1.1.1 Project Rationale One of aims of this project is to evaluate the outcomes of an investigation in 2005 that considered the potential constraints to urban development from shallow water tables in a wider urban growth area, with Cranbourne West at its Western edge (SKM, 2005). SKM (2005) highlighted the potential for the occurrence of shallow groundwater to be a risk for parts of the Casey Cardinia growth corridor; Cranbourne West was one area identified at high risk (Figure 1). The City of Casey is already in the process of developing a long term urban growth plan for Cranbourne West and it is essential that the growth plan addresses the questions and issues raised in the SKM report. This project will provide essential hydrogeological data on which to base appropriate stormwater and groundwater management so that urban salinity in the area can be avoided.

Figure 1. Groundwater constraints to urban development in area surrounding Cranbourne West (detail of figure from SKM, 2005).


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It is important to stress that this project is only meant to be preliminary. We will investigate the feasibility of using groundwater as part of the urban supply and assess whether a trial project is recommended but we will not actually run a trial. Therefore, water quality assessments for this project are not extensive but rather indicative of how much more testing would be needed for a trial.

1.1.2 Project Objectives To determine if and how significant a risk shallow water tables in Cranbourne West are to the

proposed urban development for that area.

To assess the feasibility of using groundwater as part of the urban water supply for Cranbourne West and determine if a trial project is recommended.

To propose a scheme for integrating stormwater and groundwater management.

Expand our knowledge and experience of:

the hydrogeology in the Cranbourne West area; this will provide a stronger foundation for future urban development in the Casey Cardinia growth corridor

proactive management of shallow water tables in an urban development so as to prevent urban salinity

integration of groundwater and stormwater management into urban development

some practical aspects of groundwater usage in an urban development (like an estimated life cycle analysis of the pumping infrastructure and how to estimate sustainable yields).

1.2 Report Objectives This report brings the project findings together to further develop our understanding of hydrogeology in the Cranbourne West area (Milestone 5). It is also intended to provide information that is useful to the Cranbourne West urban growth plan.

The Milestone 5 objectives are to:

Further develop the hydrogeological model;

Evaluate potential uses for the groundwater based on the estimated sustainable yield and water quality;

Assess whether there are opportunities to enhance groundwater recharge through integrated stormwater management;

Investigate whether construction, drainage, irrigation or location of open space needs to allow for shallow water tables; and to

Assess if a future trial project to extract groundwater is warranted.



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2. Relevant Investigations and Data Sets

2.1 Data Sets and Geological Information Sources The Victorian Groundwater Database (Groundwater Management System, GMS) is the primary source of groundwater data for this project. Geological maps released at various scales provide details of surface features of the local geology. The Port Phillip and Western Port Groundwater Flow Systems report (Dahlhaus et al., 2004) provides another perspective on geological interpretation.

2.2 South East Water Limited South East Water has a waste water treatment plant immediately north of the Cranbourne West site. There are three shallow groundwater bores at the treatment plant. Data for groundwater level and groundwater quality from one or more of the bores on 4 measurement dates has been provided to SKM and used in the analysis. Geological logs for each of the bores are also included in the investigation.

2.3 Private Landholders A number of reports were made available to this study from private landholders with larger land holdings at Cranbourne West. The report most relevant to this study is a hydrogeological investigation at 570 Hall Rd. (Lane Consulting, 2005), it provides details of the construction and measurements made in 4 shallow groundwater bores.

2.4 Draft Reports for Cranbourne West Development A number of draft reports for the Cranbourne West development have been made available through the website maintained by David Lock and Associates. Two reports have provided some context to this Stage 1 report: the Environmental Site Assessment (GHD, 2006); and the Water Sensitive Urban Design: Draft Issues report (Ecological Engineering, 2006).

2.5 Further Consultation with Experts Discussions were held with key experts during the initial ‘key issues’ workshop and the design workshop or independently. Representatives of Dept. of Sustainability and Environment (DSE), Victorian Environmental Protection Agency (EPA), Southern Rural Water (SRW), Dept. of Primary Industries (DPI) and South East Water Limited (SEWL) have been consulted about the availability of data. Discussions are continuing with Ecological Engineering about groundwater and stormwater management in the South West of the site.



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3. Cranbourne West: Desktop Study of the Catchment Setting

3.1 Overview The setting of the Cranbourne West Urban Growth Area within a larger catchment is fundamental to an understanding of the land, stream and groundwater hydrology. Cranbourne West is located west of Cranbourne township and between Port Phillip and Western Port Bays. The Cranbourne West site lies near the top of a small coastal catchment draining to Port Phillip Bay as shown in Figure 2 and Figure 3.

Figure 2 and Figure 3 include topographic catchment boundaries evaluated using land surface elevation data supplied by City of Casey. Surface runoff of rain water within these boundaries is expected to leave the catchment as a single stream or river. There are three subcatchments outlined in red in the figures that represent separate “stream systems” that cross the Cranbourne West site.

The catchment boundary for groundwater flow is often not the same as the boundary for surface runoff. At Cranbourne West the groundwater catchment boundaries are likely to lie close to the topographic boundary near the top of the catchment because the less permeable basement rock layer slopes upward and outcrops at the land surface along the highest points in the catchment (along the ‘divide’ between basins draining to Port Phillip and those draining to Western Port). Furthermore, the available watertable measurements indicate a relatively shallow (and elevated) watertable at the highest points in the catchment. The groundwater catchment boundaries are likely to be much less well defined by topography in the areas with the lower land surface elevations within the Cranbourne West development area.

3.2 Groundwater Management Area The Cranbourne West development area is located within the Frankston Groundwater Management Area (GMA) boundary administered by Southern Rural Water. The GMA covers aquifers at all depths as it is considered that there is some degree of hydraulic connection between aquifers in the area.

The term ‘groundwater beneficial use’ describes the most appropriate use for groundwater as defined by its salinity and measured by its total dissolved solids (TDS) content. The beneficial use of Victorian aquifers has been defined over a broad scale on published maps which represent a generalised indication of groundwater salinity (DCNR, 1995).

The beneficial use of groundwater in the study area includes beneficial use categories A2, B and C (DCNR, 1995) described in Appendix C. These categories span groundwater quality ranging from



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500 mg/L TDS (Total Dissolved Solids) to 13,000 mg/L TDS. There is significant variation in groundwater quality noted in and around the Cranbourne West site.

344000 346000 348000 350000

5776000

5778000

5780000

5782000

5784000

5786000

5788000

Figure 2. Cranbourne West Urban Growth Area (shown in green). The following features are shown: topographic catchment boundaries (red lines); direction of flow of surface runoff (blue arrows); roads (black lines); existing urban areas (diagonal hatching).

Easting (mE)

Not

hing

(mN

)



6

Figure 3. 3D Land Surface Representation of catchment including Cranbourne West Urban Growth Area (mAHD). The study site is outlined in green, roads are black lines and topographic catchment boundaries as pink lines. [mAHD = metres above Australian Height Datum, approximately the height above sea level at high tide]



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3.3 Summary of Geological Units The rock layers or rock formations with different origins and from different times in the geological scale, are referred to as geological units.

The near-surface geological units in the area surrounding the Cranbourne West site are shown in Figure 4. The main regional geological units are described below from most recent to oldest (see Queenscliff 1:250,000 Geological Map, Geological Survey of Victoria, 1971).

Figure 4 Overview of land surface geology at the Cranbourne West site (derived from

Queenscliff 1:250,000 Geological Map, Geological Survey of Victoria, 1971). Refer to the text in this report for a description of the five relevant geological units shown (Nxx, Po, Sm, Qd2 and Qm1).



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3.3.1 Quaternary Swamp Deposits This geological type is labelled Qm1 in Figure 4 and includes swamp, lagoonal and marine deposits; mangrove swamp, salt marsh, clay, silt, peat and mud. This unit tends to include many clay layers and is relatively impermeable. It lies at the lower elevation northern end of the Cranbourne West site and will only allow slow movement of groundwater out of the catchment.

3.3.2 Quaternary Dunes This unit is labelled Qd2 (Figure 4), and comprises calcareous and siliceous sands, dune limestone and sand sheets (includes Cranbourne Sand). Sand units generally have high permeability.

3.3.3 Baxter Sandstone The Baxter Sandstone is labelled Nxx (Figure 4) and is described as ferruginous sandstone, sandy clay and ligneous clay. It is an upper Tertiary unit and is expected to be of low to medium permeability at Cranbourne West although this will need to be further investigated. Weathered sandstone can occasionally form sand lenses, porosity in unweathered sandstone is primarily due to fractures.

3.3.4 Older Volcanics The older volcanics (labelled Po in Figure 4) are a lower Tertiary basalt – igneous lava flow. Typically basalt weathers to a low permeability black clay and unweathered layers form low permeability fractured rock aquifers.

3.3.5 Silurian basement The Silurian basement (labelled Sm in Figure 4), is comprised of mudstone, claystone and sandstone. Typically this unit has low hydraulic conductivity and groundwater flows through a series of fine fractures in a largely impermeable rock matrix. This unit slopes up and outcrops along the ‘divide’ between Port Phillip and Western Port Bays.

3.3.6 Lower Tertiary geological layers The Lower Tertiary rock layers often include permeable sands and gravels. They do not occur near the land surface at Cranbourne West and therefore do not appear in Figure 4. If they have the right properties, these permeable rock layers are considered to be good targets for extracting groundwater and for using in aquifer storage and recovery (ASR) projects. Some groundwater bore logs within the Cranbourne West catchment identify layers of a Lower Tertiary Unit but the indications are that they occur in small isolated areas and are not sufficiently thick to be targets for extracting groundwater.



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3.4 Hydrogeology

3.4.1 Groundwater Flow Systems The Cranbourne West site includes two groundwater flow systems identified in the report: Port Phillip and Westernport Groundwater Flow systems (Dahlhaus et al., 2004). These are:

GFS 7: Local and intermediate flow systems in the fractured Older Volcanics

GFS 10: Local and intermediate flow systems in the Brighton Group sediments (including Baxter Sandstone)

The groundwater flow systems report provides a useful but necessarily generalised context to catchment hydrology within areas of particular GFS types. For example, it is noted that GFS 10 is susceptible to salinity problems in some areas.

Ideally, the groundwater conditions that are local to Cranbourne West should be quantified including the thickness and hydraulic conductivity of all the significant geological layers on site. GFS 7 and GFS 10 are primarily local flow systems with short groundwater flow paths at the Cranbourne West site. This suggests that they would be responsive to management and that volumes of groundwater within the systems are not large.

The GFS approach supports the development of a conceptual hydrological model of the site below.

3.4.2 Frankston Groundwater Management Area The Frankston Groundwater Management Area GMA is shown in Figure 5. A GMA is proclaimed when groundwater use within the area is considered to be significant and when a co-ordinated management approach is advantageous to environmental and/or resource management outcomes.

Notes about the GMA indicate that groundwater use is primarily targeting ‘Brighton Group’ aquifers which typically have medium to low permeability and were deposited over the same geological period as the Baxter Sandstone noted in Figure 4.



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Figure 5. Frankston Groundwater Management Area (highlighted in purple).

The boundaries of the GMA are as follows: western boundary coincides with the coastline and extends from Carrum in the north to Frankston in the south. The northern boundary follows the Eumemmerring Creek which drains to the Patterson River and flows to the coastline at Carrum. The eastern boundary follows the parish boundary of Cranbourne and Lyndhurst. The southern boundary extends from Frankston on the coast along the Frankston-Cranbourne Road until it intersects the Cranbourne/Lyndhurst parish boundary.

The Permissible Consumptive Volume (PCV) for the Frankston GMA is 3200ML per year. Currently 1118.6ML (35%) of the 3200 ML is allocated to licensed users for purposes such as irrigation, commercial or industrial.

3.4.3 State Observation Bore Network: Waterlevel Monitoring There are only six DSE State Observation Bore Network (SOBN) bores that are regularly monitored within the Frankston GMA boundary. Four additional bores were monitored in the past



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but have been decommissioned. All of the SOBN bores are located in the proximity of the Cranbourne Landfill, Waste Transfer Station and the Cranbourne Training Complex.

These SOBN bores are all less than 16 metres in depth except for one at 30 metres. These bores are monitoring watertable conditions and lie just outside the Frankston GMA. There is no regional waterlevel monitoring currently being undertaken in the Frankston GMA.

There are no ongoing water quality monitoring programs currently being undertaken within the Frankston GMA boundary, nor within the vicinity of the Cranbourne West development area.

3.5 Observed Groundwater Levels The groundwater bores in the area surrounding Cranbourne West with recorded time series of groundwater levels are shown below (Figure 6). Measurements made on 14 December 2006 (see Section 4.1) are also shown.

The time series groundwater levels recorded over the period 1987 to 2006 are shown in Figure 7. The results are dominated by a group of 8 bores at the Cranbourne botanical gardens (data only recorded from 1990 to 1991 for 6 of these) and another group of 6 bores nearby at a landfill site. The hydrographs at the botanical gardens and the landfill show some variation in groundwater level but no consistent trends of increasing or decreasing level over the period. These groundwater bores occur in an area of Quaternary Dune sand (see Figure 6 and Figure 4). A reasonably constant average groundwater level over a number of years is likely to indicate a good balance between annual groundwater recharge of this unit and annual loss of groundwater from the unit. A reliable annual groundwater recharge volume may come from irrigation of residential gardens, the botanic gardens and other public amenities.

In contrast, two groundwater bores north of Cranbourne West (62950, 62949) show a slight rise in level from 1987 to 1998 and declining groundwater level since 1998. These changes are likely to be a muted response to rainfall variation over the period. Rainfall variation is represented in Figure 8 that shows the cumulative residual rainfall over the period. Comparison by eye suggests the time trends in groundwater level in bores 62950 and 62949 (Figure 7) follow a similar temporal pattern to cumulative residual rainfall (Figure 8) confirming the climatic response of groundwater levels in these bores.

Groundwater bores 62950 and 62949 are at the same site and monitor groundwater potential at different depths (screens at 54 m and 14 m respectively). It is clear that there is almost no vertical gradient in groundwater potential between these two depths at this site. This observation suggests good hydraulic connection between the depths and no significant vertical component to groundwater flow at the site (i.e. flow is lateral). Data from groundwater bores at the SEWL site



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are not plotted in Figure 7 as the relative elevation of the bore casing and the land surface are not known at this site.

343000 344000 345000 346000 347000 348000 349000 350000 3510005775000

5776000

5777000

5778000

5779000

5780000

5781000

5782000

5783000

5784000

5785000

5786000

5787000

CBH8CBH9

6295062949

BH2GW1GW2GW3

GW4

CBH3

CBH1CBH2

76206to

76210910809108191766to91771

SEWL3

SEWL2 SEWL1

Figure 6. Locations of groundwater bores with more than one reading of groundwater level. Data at these bores is presented in the following figure.



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0

2

4

6

8

10

123/05/1987 27/01/1990 23/10/1992 20/07/1995 15/04/1998 9/01/2001 6/10/2003 2/07/2006

Dep

th B

elow

Nat

ural

Sur

face

(m)

57178 57179 57180 76206 76207 76208 76209 76210 91080 91081 9176691767 91768 91769 91770 91771 62949 62950 BH 2 CBH 1 CBH 2 CBH 3CBH 8 CBH 9 GW 1 GW 2 GW 3 GW 4

Figure 7. Groundwater bore hydrographs in the Cranbourne West catchment.

-400

-200

0

200

400

600

800

1000

1200

Sep

-87

Sep

-89

Sep

-91

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-93

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-95

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-97

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-99

Sep

-01

Sep

-03

Sep

-05

Cum

ulat

ive

resi

dual

rain

fall

(mm

)

Figure 8. Cumulative residual rainfall at Narre Warren (station number 86085) over the

period of the bore hydrograph record.



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Observations of groundwater levels in and around the Cranbourne West site suggests that two areas with shallow watertables occur (depth to watertable <= 2 m below land surface). These are located in the north east corner of the Cranbourne West site (in the vicinity of the retarding basin) and in the south west corner of the site and may be limited to these areas under the current conditions of catchment hydrology. The south west corner of the Cranbourne West development site was chosen for further investigation (see below). The data indicate that areas prone to shallow watertable conditions (depth to watertable <= 2 m below surface) occur in the South West and North East corners of the site. The shallow watertables noted in the earlier study (SKM, 2005) are noted here in the South Western corner of the Cranbourne West site.

3.6 Groundwater Salinity The State Groundwater Database (GMS) includes some time series for groundwater salinity in the area surrounding Cranbourne West (Figure 9). The available data at different bores are often recorded years apart and do not provide a consistent record.

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

2/12/1973 25/05/1979 14/11/1984 7/05/1990 28/10/1995 19/04/2001 10/10/2006Date

EC (u

S/c

m)

57178 57179 57180 76206 76207 76208 76209 7621091080 91081 122071 62949 62950 BH 2 CBH 1 CBH 2CBH 3 CBH 8 CBH 9

Figure 9. Time series of groundwater salinity recorded around the Cranbourne West site.

Groundwater salinity is variable in the area and the highest groundwater salinities do not appear to be associated with sites where shallow watertables occur.



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4. Field Investigations

4.1 Description of Measurements 14/12/06 Measurements were taken in a number of existing groundwater bores in or around the Cranbourne West development site on 14 December 2006. The groundwater bores that were monitored included selected bores installed for the “Groundwater Constraints” investigation (SKM, 2005) and four bores installed on one property within the Cranbourne West development site.

The field measurement results are summarised below in Table 1.

Table 1. Summary of groundwater measurements made 14/12/06. Refer to Figure 6 for a map of bore locations.

Bore Identifier Location

Depth to Watertable from land surface (m)

Watertable level (mAHD)

Groundwater Salinity (μS/cm)

BH2 Cnr Hall Road and Westernport Hwy, Cranbourne West 3.1 28.16 1671

CBH8 JP Camms Reserve, Cranbourne 6.39 41.61 2504

CBH1 Browns Road, Cranbourne South 1.7 70.26 7860

CBH2 Cnr Browns Road & Fletcher Road, Cranbourne South 15.19 52.31 not taken

CBH3 Adrian Street, Cranbourne East 3.6 43.76 242

CBH9

Narre Warren-Cranbourne Road, Cranbourne East (opposite Loch St) 3.83 38.36 1421

GW1

Apco Service Station, Cnr Hall Road and Westernport Hwy, Cranbourne West 3.65 30.14 not taken

GW2


GW3


GW4

570 Hall Rd., Cnr Hall Road and Westernport Hwy, Cranbourne West 0.94 38.5 not taken

In general the measurements show good consistency with earlier readings in these bores although watertable levels are lower by approximately 1 m and this is thought to be a response to lower than average rainfall over the last few years.



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4.2 Field Investigations May 2007

4.2.1 Overview Field investigations in May 2007 aimed to provide more information about the geological setting in the South West of the development site. Specifically, the primary aims to be served in the location of the new groundwater observation bores were to:

enlarge the data sets for groundwater level and salinity in the south west of the Cranbourne West growth area;

investigate the nature of the hydraulic properties in the basalt and the sand geological layers, and the differences between these two units; and

investigate the extent of the sand layer south of the basalt flow in terms of both depth and lateral extent.

Field activities were undertaken by SKM in two parts:

a) Drilling 4 new groundwater bores, and

b) hydraulic testing of the aquifer and extraction of groundwater samples from new and existing bores in the area.

The location and elevation of the new groundwater bores were measured by a sub-contractor, Timcke and McIntosh Surveying.

The four groundwater bores were drilled during the week of 7-11th May 2007 by Aqua Drilling and Grouting, and supervised by SKM personnel. This was followed by a survey of bore location completed on May 18th by Timcke and McIntosh Surveying.

4.2.2 Groundwater Bore Construction Groundwater observation bores were constructed on the days shown in Table 2. It should be noted that the development of bore CW4 was delayed until the following week due to the break-down of the drill-rig.

Table 2. Timetable of groundwater bore construction.

Activity (May 2007)

Bore name/number Location Drilling Construction Development

CW1 250 Hall Rd Mon 7th Mon 7th Wed 9th

CW2 250 Hall Rd Tue 8th Tue 8th Wed 9th

CW3 Yanco Wed 9th & Thu 10th Thu 10th Fri 11th

CW4 Mondous Fri 11th Fri 11th Mon 14th



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The drilling methods included downhole hammer drilling for the one bore drilled into basalt, and mud rotary drilling for the three bores drilled into sands and clays.

During drilling a hydrogeologist from SKM logged samples of the cuttings coming from the rig every metre. Depth to groundwater was noted where possible (mud drilling uses water and therefore the watertable can often be difficult to estimate). Any change in rig ‘behaviour’ was also noted; this often indicates a change in geology. The Hydrogeologist also directed the depth of drilling and the final construction of the bore, that is, the bore was constructed so that information obtained would be characteristic of the aquifer of interest. Groundwater bore development (this involves pumping groundwater out of a bore until it is ‘bedded in’) was carried out by the drillers and involved air lifting drilling fluids and fines from the bore produced during drilling activities. When the groundwater was running clear and was free of sand and fines, and the Hydrogeologist was satisfied with the water quality, the bore development was complete. This activity took between 2-3 hours.

4.3 Groundwater Sampling and Hydraulic Testing Groundwater samples were extracted from 5 bores. These included 2 existing bores; GW2 and GW4, and 3 of the recently drilled bores; CW1, CW3 and CW4. It was attempted to extract a sample from a sixth bore (BH2) but the water level in this bore was found to be too close to the bottom of the bore. Groundwater bore CW2 was not sampled because it was sited alongside GW2.

Groundwater sampling was completed by either pumping groundwater out of the bore with an electric pump or in the case of bore CW4, a bailer was used. Three well volumes were removed from each bore to ensure fresh water from the aquifer was being sampled. Groundwater samples were sent to a laboratory for analysis of electrical conductivity, TDS, nitrate, nitrite, E.Coli, Na, Ca, Mg, K, SAR, Alkalinity (CaCo3), pH, total Nitrogen, total Phosphorus, OPP, OPC.

Hydraulic aquifer testing using a standard ‘slug test’ was undertaken in the same groundwater bores. This involves causing the water level within the casing of a groundwater bore to instantaneously rise (or fall) by a significant height and then observing how quickly water leaves the bore (or groundwater enters the bore) to re-establish the local groundwater level.



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5. Field Data Analysis

5.1 New Groundwater Observation Bores A summary of new groundwater bore locations and some bore details is given in Table 3. The locations of the new bores are also shown in Figure 10. Bores CW1 and CW2 were located close to existing shallow bores (GW4 and GW2 respectively).

Table 3. New groundwater bore locations with some details.

Bore name/ number

General location

Bore depth drilled to (m)

Screened interval* (m below surface)

Main Geology Encountered Easting (MGA

Coordinates) Northing (MGA Coordinates)

CW1 In paddock 200m East of W'Port Fwy

31.5 11 m to 17 m

Sands and Clays

345193.83 5779717.11

CW2 At rear of APCO Service Stn

24 9 m to 12 m

Weathered Basalt

345206.3 5780595.43

CW3 At southern boundary of ANCO Turf Farm

31.5 20.5 m to 20.5 m

Sands and Clays

345402.65 5779150.88

CW4 Near NW cnr of Golflinks

20 11.6 m to 13.6 m

Sands and Clays

345841.63 5779711.77

* Screened interval is the depth range over which groundwater is permitted to enter into the bore. In the case of groundwater bores where the screen lies above the drilled depth, the bores are backfilled to 1 metre above the base of the screen.



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343000 344000 345000 346000 347000 3480005778000

5779000

5780000

5781000

5782000

5783000

5784000

5785000

CW

1C

W2

CW

3

CW

4

BH

2G

W2

GW

4

Figure 10. Map showing the location of new and old groundwater bores used in the field investigation in May 2007. Roads are shown as thin black lines and the Cranbourne West urban growth area is outlined with a thick black line. There are two pairs of groundwater bores that are sited close to each other: GW2 & CW2, and GW4 & CW1.

The geological layers encountered during drilling of the new bores are shown as bore logs in Appendix A. A sand layer approximately 15 m to 20 m thick was logged at groundwater bores CW1 and CW3. Bore CW4 appears to be sited at the edge of the basalt flow – this indicates that the basalt lies further south than represented in Figure 4. Bore CW2 is sited on the basalt with some basalt layers weathered to clay.



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Clayey SandClay

Clayey Sand

Silty Sand

Silty Clay

Basalt

Basalt Clay

Clay/Some sand

Basalt Clay

Clayey Sand

Clay and Silt

Sand

Clay and SiltSand/PeatBedrock

Clay

Silty Clay

Coarse Sand

Silty Clay

Bedrock

0

5

10

15

20

25

30

35

CW1 CW3 CW4 CW2

Dep

th

Figure 11. Interpreted geological profiles at the new bore sites.

Interpretation of geological layering is presented as cross-sections in Section 6.4 below.

The groundwater levels recorded in the bores in May 2007 are shown in Figure 12 as depth below natural surface. Water levels in bores CW1, CW3 and CW4 represent the groundwater potential in sand layers that are partially confined by overlying soil/geological layers of lower permeability. For example the sand layer between 11 m and 25 m in groundwater bore CW3 (Figure 11) is overlaid by approximately 10 m of clay. The groundwater potential in the sand layer gives a water level in the bore at 0.86 m below the land surface (Figure 12) whereas the watertable in the clay layer is thought to be deeper at approximately 3 m.



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345000 345500

5779200

5779400

5779600

5779800

5780000

5780200

5780400

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5780800

5781000

0.18

4.94

0.86

4.26

4.97

1.08

Hall Rd

Wes

tern

port

Hig

hway

Figure 12. Cranbourne West: water levels observed in groundwater observation bores May 2007 (metres below natural surface). Note that some groundwater bores are screened in semi-confined sand layers.

New groundwater bore CW1 is located close to existing shallower groundwater bore GW4 (approximately 100 m away). However, groundwater level observed in CW1 is higher than in bore GW4 (Figure 12 and Table 4) suggesting that a deeper, more permeable sand layer is at a higher groundwater potential and is confined by the overlying clay-rich near-surface soil layers (shown in Figure 11). It is likely that groundwater is moving up through the surface clay layers from below. Table 4 presents measurements of groundwater levels in bore GW4 (depth 6 m) since the bore was installed in 2005. The persistence of a shallow watertable in GW4 over a two year period under dry antecedent climatic conditions supports the hypothesis that groundwater potentials in a more permeable layer beneath are maintaining the shallow watertable above.

In the context of the above discussion it is important to note the following:



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GW4 and CW1 are separated by 100 m and spatial heterogeneity may contribute to the differences in readings;

bore GW4 is sited within 30 m of a farm dam on an adjacent property – the water level in this dam would be well above the surrounding land surface when it is full [if the dam is properly constructed seepage should be very low and groundwater will not be greatly affected];

an upward hydraulic gradient at this location is quite feasible given that the bores lie at a low point in the local landscape and groundwater flow from higher in the catchment may converge in the area surrounding this bore before continuing ‘down-catchment’; this is discussed further below in the hydrogeological conceptual model.

Table 4. Observed depth to watertable (m) in groundwater bore GW4

Date Groundwater Level below natural surface

(m)

Reduced groundwater Level (mAHD)

GW4 CW1 GW4 CW1 8 / 9 / 2005 0.16 m * 39.58 m *

14 / 12 / 2006 0.94 m * 38.80 m * 24 / 4 / 2007 1.26 m * 38.48 m * 22 / 5 / 2007 1.08 m 0.18 m 38.66 m 40.03 m

5.2 Hydraulic Testing of Aquifers The hydraulic conductivity of the aquifer units encountered at Cranbourne West was investigated by undertaking simple “slug” tests on May 22nd and 23rd, 2007. These tests effectively add and later remove a known volume of water within a bore and observe the movement of water from the bore to the aquifer or vice versa. The analysis of data collected in hydraulic testing is summarised in Appendix B.

The data sets collected allow calculation of aquifer hydraulic conductivity (K) and as expected the K values show a clear differentiation between the sands and the basalt (Table 5).



23

Table 5. Summary of results for hydraulic conductivity measured in groundwater bores.

Bore ID Geology Hydraulic conductivity (K) range (m/day)

CW1 Sands 2.399 - 2.462 GW4 Sands 1.343 - 1.851 CW4 Sands 3.046 CW3 Sands results inconclusive GW2 Basalt 0.2927 – 0.704

Bore CW3 at the turf farm was tested a number of times, however results are deemed inconclusive as it was very difficult to apply a rising head test with very shallow water tables.

5.3 Groundwater Chemistry The results of the laboratory chemical analysis of 5 groundwater samples are summarised in the following table (Table 6). The results can be compared to the Australian Drinking Water Guidelines (2004) and the ANZECC Recreational Water Guidelines (2000) in the table. The following discussion was provided by Wendy van Dok (City of Casey).

E coli E.coli is one type of thermotolerant coliforms which are present in the gut of humans and other warm blooded animals. E.coli is used as an indicator species of faecal contamination of water.

All groundwater water samples had E.Coli readings less than 10 organisms per 100mL which is very low. Potable water uses would require zero E.coli but this groundwater meets the EPA requirements for urban use with uncontrolled public access like irrigation. ANZECC 2000 Guidelines recommend that the median bacterial content of recreational waters used for primary contact e.g. swimming, should not exceed 150 faecal coliform organisms/100 mL.



Table 6. Summary of laboratory chemical analysis of groundwater samples extracted from the Cranbourne West site.

Parameter

analysed

Units NH&MRC 2004

Drinking Water Quality Guidelines

ANZECC 2000

Recreational Water Guidelines

Bore site

GW2 CW1 GW4 CW4 CW3

E.coli org/100mL 0 org/100mL see below <10 <10 <10 1 <10 Organochlorine pesticides

µg/L

Not detected

Not detected

Not detected

Not detected

Not detected

Organophosphorus pesticides

µg/L

Not detected

Not detected

Not detected

Not detected

Not detected

pH 6.5-8.5 5-9 6.7 5.9 6.1 6.0 6.2 Total Alkalinity mgCaCo3/L 230 48 120 53 42 Electrical conductivity

µS/cm 3330 1669 3490 1598 1093

TDS mg/L Taste 500mg/L 1960 1000 2200 710 1100 SAR me/L me/L 9.1 10.1 15.3 7.0 12.6 Nitrate mgN/L see below 1.5 <0.01 <0.01 0.02 <0.01 Nitrite mgN/L see below <0.01 <0.01 <0.01 <0.01 <0.01 Total nitrogen mgN/L 1.7 0.2 0.5 0.3 0.5 Total phosphorus mgP/L 0.59 0.06 0.05 0.04 <0.01 Calcium mg/L 87 17 27 14 7 Magnesium mg/L 130 44 90 32 29 Sodium mg/L Taste 180mg/L 406 245 522 147 240 Potassium mg/L 1.0 2.2 0.7 1.5 1.6 Note: CW2 was not sampled because the bore next to it, GW2 was, and BH2 which was supposed to be sampled for WQ analysis, ended up being too shallow a bore and the water table too low to take samples as per groundwater sampling guidelines.


SINCLAIR KNIGHT MERZ The SKM logo is a trade mark of Sinclair Knight Merz Pty Ltd. © Sinclair Knight Merz Pty Ltd, 2006


Salinity Salinity is a measure of the concentration of total dissolved solids or TDS which are mostly salts in water. It can be expressed as a concentration of salts e.g. milligram/litre (mg/L) and parts per million (ppm) or as conductivity (salt solutions conduct electricity) which is expressed as micro Siemens/cm (µS/cm). As a guide, ppm = mg/L which is approximately equal to µS/cm x 0.6. In other words, 1 ppm =1 mg/L which is approximately = 0.6 µS/cm. The terms milli Siemen (mS) and deci Siemen (dS) are also used. 1dS/m = 1mS/cm =1000 µS/cm. As a reference point, seawater is about 60,000 µS/cm.

The salinity of groundwater from the five sites in Cranbourne West as measured by TDS and EC are very high relative to Melbourne tap water, which is about 50 µS/cm, but low relative to water used for horticultural and agricultural irrigation. The trouble is, agricultural land across Australia had been badly affected by salinity and so it is questionable whether acceptable agricultural salinity standards for irrigation water are a good benchmark in an urban context. Moreover it is difficult to stipulate what salinity level is suitable for open space irrigation because it will depend on a range of variables like plant species, soil type, climate, how well the soil gets flushed, irrigation efficiency and the likelihood of runoff or leaching. For example, plants like clover are particularly sensitive to salt and are thus used as a salinity indicator species.

There are several published guidelines which relate to the salinity of treated effluent that can be used as a guide for groundwater because there is very little about groundwater salinity per se. The SEPP, Groundwaters of Victoria, considers that groundwater in the range of 1,000–3,500 µS/cm is suitable for agriculture, parks and gardens. However, in Casey, this could exacerbate the potential for urban salinity in areas like Cranbourne West which have a shallow water table.

Another publication titled Physical and Chemical Quality of Drinking Water, published by the then Victorian Department of Conservation and Natural Resources in 1995, classifies water in the range of 800–2,500 µS/cm as medium salinity which requires adequate leaching and may be a problem if used on soils with restricted drainage. It also stresses the need to consider the salt tolerance of plants when using water of medium salinity. EPA Pub 464.2, 2003, Use of Reclaimed Water states that treated effluent with a salinity in the range of 780 µS/cm –2,340 µS/cm or 500 ppm–1,500 ppm is Salinity Class 3 with the qualification that... “The more saline waters in this class should not be used on soils with restricted drainage. Even with adequate drainage, best practice management controls for salinity may be required and the salt tolerance of the plants to be irrigated must be considered”.

All these guidelines so far refer to water and salts coming into contact with soil and plant roots, the problem could be worse if the water is sprayed on the foliage during hot windy weather where it may be concentrated by evaporation and where the effects of chlorine may also be magnified.



I:\VWES\Projects\VW04032\Deliverables\Casey_SWF_Final_Sept26.doc PAGE

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Based on the NH& MRC Guidelines, TDS in drinking water should not exceed 500mg/L in terms of taste. The palatability of water deteriorates significantly over 800mg/L.

Sodium and SAR The actual sodium concentration and ratio of sodium to magnesium and calcium can be more instructive than overall salinity in terms of the suitability of water for landscape irrigation. Excessive levels of sodium relative to calcium and magnesium, also known as the sodium absorption ration (SAR), can adversely impact on soils and plant growth and make soil sodic. Sodic soil disperses and erodes easily and generally does not drain well. Clay soil is particularly susceptible to sodicity. As water movement or hydraulic conductivity is impeded in sodic soil, the ability of rainfall to leach away the salts is also impeded and so the situation becomes exacerbated. One set of Guidelines from California suggests that irrigation water with a sodium concentration greater than 70 mg/L or is likely to cause increasing problems for soil and plants. The sodium concentration of the groundwater in Cranbourne West ranges from 147- 522 mg/L which is very high. The SAR of groundwater ranges from 7-15, which, according to the NSW Environmental Guidelines: Use of effluent by irrigation, is in the range of irrigation waters that are likely to cause soil structural problems. EPA Pub 464.2 states that an SAR of 3 represents a trigger level for further investigation about the suitability of its continued use.

As far as sodium levels in drinking water are concerned the NH&MRC Guideline for taste threshold is 180mg/L but people with severe hypertension or heart problems should be cautious of water containing more than 20mg/L.

Nutrients Total nitrogen and phosphorus concentrations are generally low at all sites except GW2 although why this particular site is elevated is unclear. It could relate to previous land use or conditions at this low-permeability basalt site. Management of runoff will be important at any site where this groundwater is used for irrigation. Nutrient levels in groundwater fall below the guidelines for water quality for irrigation of constructed wetlands except for GW2 (total N: 0.35 to 0.7 mg/L; total P: 0.01 to 0.1 mg P/L) and thus the risks associated with use of the groundwater are low. Benefits to plant productivity from nutrients present in the water are expected although they may not be significant. This report recommends use of groundwater in a scheme where the site of irrigation would be monitored and in particular runoff from the site would be strictly controlled.

Nitrate and Nitrite Nitrite and nitrate are two chemical forms of nitrogen that have human health implications if they reach critical levels in drinking water. Nitrate is readily converted to nitrite by microorganisms. Very high nitrite (NO2) concentrations have been recorded in groundwaters largely as a consequence of nitrogenous fertiliser runoff and leaching or from leaking septic tanks and from inappropriate use of treated effluent in the landscape. High concentrations of nitrite in ground water




27

have been implicated in the condition known as methaemoglobinaemia, where the ability of blood to carry oxygen is impaired. Young infants and pregnant women are the most vulnerable. The ANZEC Drinking Water Guidelines suggest that the concentration of nitrite in drinking water should not exceed 3 mg NO2/L and for nitrate, 50 mg NO3/L for bottle fed infants under three months of age. Up to 100 NO3/L can be safely consumed by older children and adults. Fortunately the concentrations of nitrate in the Cranbourne West samples are well below these levels at all sites.




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6. Data Interpretation

6.1 Overview In this section the above information is drawn together to describe the hydrogeological context of the Cranbourne West urban development. Sections 6.2 and 6.3 present an overview of the depth to watertable and groundwater salinity in and around the Cranbourne West site. Then we interpret the geological stratigraphy in three cross-sections of geological layers. A summary of information about the site is then used to support development of a conceptual model of the shallow groundwater system, with particular focus on the southern end of the Cranbourne West growth area.

Section 6.2 below indicates that shallow watertables have been observed in the North East and South West corners of the Cranbourne West Urban Growth Area. It was decided that the resources provided would allow investigation of either the north east or the south west but not both; one or two bores at opposite ends of the site would not provide the detail needed to describe the groundwater system. The South West corner was chosen because it appeared to have potential for extraction of groundwater.

In Section 6.6 we focus the investigation on the shallow groundwater conditions observed in the south west corner of Cranbourne West.

6.2 Depth to Watertable Data shown earlier in this report (Figure 7) indicates the nature of the groundwater level data that is available for the Cranbourne West site. The usual practice for preparation of a spatial map of depth to watertable or groundwater level data across a site is to select a short time period in which data must be recorded and a particular geological layer that all groundwater levels are recorded within. This approach is not strictly followed in this report as explained in the following.

Below, we have collated a composite data set including all available groundwater level measurements to increase the spatial coverage of data. In this data set, nearly all groundwater bores are shallow (<= 30 m deep), the water levels in deeper bores show a reasonably close correspondence with neighbouring shallow bores and the groundwater levels are less than 10 m from the land surface. Therefore, the assumption is made that the groundwater levels indicate the depth to watertable. (This may not always be the case, as a clay-rich layer at or near the land surface can confine an underlying aquifer and reduce the correspondence between the measured groundwater potential in the aquifer and the depth to watertable as observed in a soil profile.)

The data set includes single measurements of depth to watertable made at the time of bore construction, measurements made at any date since 1973 and measurements made at all depths.




29

Where more than one measurement of depth to watertable has been made at a bore, the most recent recorded depth to watertable is used. The data set generated in this way has poor quality control and does not represent conditions on any particular date, but is useful in providing an overview of observed conditions across the site. Figure 13 shows the measurement points and an interpolated depth to watertable surface.

342000 344000 346000 348000 3500005776000

5778000

5780000

5782000

5784000

5786000

0

2

4

6

8

10

12

Figure 13. Depth to watertable (m) at Cranbourne West. This is a composite figure that has poor correspondence between the nature and quality of data points for different bores as described in the text. The locations of bores used to generate the contour map are indicated as crosses. Also shown are Cranbourne West boundary (outlined in white), catchment boundaries (pink), roads (black) and streams/drainage lines (light blue)

There are only two locations within the Cranbourne West site with a watertable at a depth less than 2 metres: at the south western corner and the north eastern corner of the site. At these locations there is a convergence of the upstream subcatchment (subcatchment boundaries shown with pink boundaries in Figure 13). It is likely that groundwater flow also converges at these locations.




30

The apparent shallow watertable area (depth to watertable < 2 m) up near the top of the catchment in the south is likely to be the result of a few shallow bores in the impermeable fractured rock (basement rock) outcropping in this area. It is highly likely that these groundwater conditions are isolated local measurements that are not relevant to the management of Cranbourne West at all.

6.3 Groundwater Salinity There are a number of factors that should be considered when evaluating data for groundwater salinity. These include the date of measurement, the geological layer from which the groundwater is sampled and the regularity of measurements.

However, in a similar way to the data for depth to watertable, we have included all available salinity measurements to increase the spatial coverage of groundwater salinity data in this report. These include single measurements of salinity made at the time of bore construction, measurements made at any date since 1973 and measurements made at all depths. Where more than one measurement of groundwater salinity has been made at a bore, an average salinity value is calculated (i.e. for the bores shown in Figure 9). The data set generated in this way has poor quality control and does not represent conditions on any particular date, but is intended to be useful in providing an overview of the order of magnitude of groundwater salinity in the study area and may also highlight areas where high salinity values could be further investigated. The data set is presented in Figure 14.

Note that some data points in the groundwater salinity map have a strong influence on the salinity ‘surface’ and that these points may be unrepresentative of average conditions for the reasons discussed above. It is interesting to note that the shallow watertable observed near the corner of Ballarto Road and the Western Port Highway does not appear to be associated with an area of high groundwater salinity.




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342000 344000 346000 348000 3500005776000

5778000

5780000

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5784000

5786000

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

GroundwaterSalinity

(microS/cm)

Figure 14. Average groundwater salinity at Cranbourne West. Groundwater bores

contributing data to this figure are shown as crosses. This is a composite figure including all available data points and therefore does not represent conditions at any particular date, see text for details.

6.4 Geological Cross-Sections The groundwater bores shown in Figure 15 have data describing the geological layers encountered during drilling for depths of approx 10 m or more; the bores drilled in this project are shown (CW1 to CW4). Groundwater bore logs from the South East Water site to the north of Cranbourne West are also used.

The lines for which geological cross sections have been drawn below are also shown in Figure 15. The cross sections represent an interpretation of geology that draws on bore logs, knowledge of local geology and experience of SKM staff in this area (e.g. the installation of an Aquifer Storage and Recovery system at Rossdale).




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5775000

5777000

5779000

5781000

5783000

5785000

5787000

340000 342000 344000 346000 348000 350000 352000

Easting

Nor

thin

g

62950

76296

76321

144144

S9023204/176496

57483

75011

133349

7629776492

76443

7638076413 76512

7656176454

75001

Sewl3

CW1

CW2

CW3

CW4

Sewl1Sewl2

Figure 15. Groundwater bores with recorded geological logs. The approximate lines of the geological cross sections are shown in blue.




33

Figure 16 is a cross section north of the site at lower land surface elevation than Cranbourne West. Whilst some dune sand has been noted in the east, the section is dominated by the near-surface clays of the Quaternary Swamp Deposits and the underlying Silurian basement. Both these units have low permeability and lie at an elevation of 20 mAHD or less; therefore groundwater flow in these units is not expected to be a significant fraction of the Cranbourne West catchment water balance.

-40

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01000200030004000500060007000Distance

mAH

D

SEWL1aSEWL1

Basement

Clay

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Bore 76496

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Geological Strata discontinuous

West of Selwyn Fault

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76496

76561

76321

76296

Dunes

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01000200030004000500060007000Distance

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Cranbourne West

Bore 76496

Bore 76321

Geological Strata discontinuous

West of Selwyn Fault

Bore 76561

76496

76561

76321

76296

Dunes

Figure 16. Interpreted geological cross section to the north of Cranbourne West (lower land surface elevation) from bore 76496 (west) to bore 76321 (east). Bore logs from bores at a South East Water site to the north of the development are also included. The interpretation of geological layers draws on knowledge of local geology.

Figure 17 is a cross-section crossing Cranbourne West diagonally from South-East to North West. The fractured basalt and fractured Silurian basement units occur at the lower end of the section and both are expected to have low permeability. At the upper end of the section some Quaternary Dune Sand is likely to contact a thin Lower Tertiary layer that is not expected to have a great extent. The dune sand and Lower Tertiary unit may provide a permeable pathway for groundwater but it is likely that water will only move laterally as far as the basalt unit (Older Volcanics) that could act to restrict significant groundwater flow.




34

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ght a

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57483

Bore

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133349

Basalt

Basement

Dunes

Sand/Peat

76512

Bore 76512

57483

Bore

57483Bore 133349

Bore 76297

Figure 17. Geological cross section cutting Cranbourne West diagonally from South-East to North West.

Figure 18 is the cross-section running North-South along Cranbourne West growth area that includes information from the bores drilled in this project. This section (like Figure 17) clearly shows a sand layer above basement and upstream of the basalt flow that dissects the site. It is likely that groundwater flow in the sands will be diverted west around the end of the basalt to the west of the Cranbourne West growth area.




35

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Basement

ClaySand

Clays

Bore 75011

Bore 75001

Bore CW

1

Bore C

W2

Bore 76512

Bore 76561

Basalt

Figure 18. North-South geological cross section of the Cranbourne West site.

6.5 Conceptual Model of the Groundwater System The findings of this project are summarised below in bullet points. This understanding is then used to describe the expected groundwater flow systems in the Cranbourne West area.

The Cranbourne West Urban Growth Area lies near the top of a small coastal catchment for surface runoff and groundwater flow, and groundwater flow systems are considered to be ‘local’. Land surface elevations range from approximately 100 mAHD to 20 mAHD within the catchment.

The soil/geology profiles are typically of low permeability and surface drainage appears to be adequate.

Groundwater flow at the Cranbourne West site is limited by shallow soil/geology profiles above basement rock and the small upstream catchment area.

Areas prone to shallow watertable conditions (depth to watertable <= 2 m below surface) occur in the South West and North East corners of the site (Figure 13) and may be limited to these areas under the current conditions of catchment hydrology.




36

The available data indicate that groundwater salinity at the Cranbourne West site ranges between 2000 and 5000 μS/cm (i.e between 1200 and 3000 mg/L Total Dissolved Solids). These groundwater salinities do not suggest widespread and significant groundwater discharge or evaporative concentration of groundwater. Furthermore, there are no signs that areas of shallow watertable are co-incident with higher groundwater salinity within the Cranbourne West site (should this occur it would be an indication that significant land and stream salinisation is likely).

In general the geological units are of low permeability (Silurian bedrock/basement, Quaternary swamp deposits, Older Volcanics (weathered and fresh) and unweathered Baxter Sandstone). The underlying Silurian basement is a fractured rock aquifer unit that lies at a depth of approximately 30 m throughout most of the Cranbourne West study area. The bedrock outcrops to the south of Cranbourne West along the divide between catchments draining to Port Philip and those draining to Westernport.

Small pockets of higher permeability geological units occur (Figure 16 and Figure 17): Quaternary Dune sands (approximate thickness 10 m) and near-surface sands (weathered Baxter sandstone). These layers have a limited spatial extent and terminate in the less permeable basalt or Quaternary Swamp deposits.

Junctions of sand units and low permeability units may provide conditions for shallow watertables to develop. Groundwater flow in higher permeability sand layers is likely to contribute to the maintenance of a shallow watertable in the south west.

Most of the groundwater bore hydrographs do not show any clear inter-annual trends in the observed depth to watertable. In contrast, two groundwater bores ‘downstream’ of the Cranbourne West site show a response to inter-annual variations in rainfall.

In the South West of Cranbourne West:

Sand layers south of the Older Volcanics basalt flow (upstream) were found to be approximately 15 m thick including coarse sand layers (CW1 and CW3, Figure 11). The thickness of the sand layer and the higher hydraulic conductivity (K) of these sands supports the hypothesis that groundwater from upstream in the catchment can move relatively easily and quickly to an area where shallow watertables are observed at bores CW1 and GW4. Under current land management, groundwater recharge from the turf farm and the golf course is likely to contribute to this groundwater movement and it is also likely that recharge in some existing residential areas of Cranbourne will contribute to groundwater flow in this area.

Bore CW2 lies in an area with a low permeability basalt layer from 0 to greater than 20 m. The K value of the basalt is an order of magnitude lower than the K of the sand layer (Table 5) and therefore it is expected that the basalt impedes groundwater movement further down the catchment. Some groundwater flow is likely to be diverted laterally to the west (west of the




37

Western Port Highway) around the end of the basalt flow and some discharge to drainage lines may occur in this area.

Bore CW4 was found to be at the boundary between the basalt and the sand areas.

Our developing conceptual model of the groundwater system in this area is as follows; Figure 19 provides some contextual information. Groundwater flow appears to converge on the south western corner of the Cranbourne West growth area from a large contributing area south and up-gradient. This groundwater flow meets an ‘Older Volcanics’ basalt layer of low permeability (Figure 19) and is largely diverted to the west. Near-surface groundwater levels are observed where the groundwater flow is impeded by the presence of the basalt.

At the northern end of Cranbourne West the profiles are of low permeability and low elevation relative to sea level. It is assumed that surface drainage in this area is adequate and this will be important for maintaining suitable conditions for urban development.




38

Figure 19. Land surface elevation (mAHD) at the southern end of the Cranbourne West Growth Area. Roads are shown as black lines, the boundary of the development as a green line and the area with a purple boundary is a surface layer of basalt (basalt outline from Geological Survey of Victoria, 1971). Our interpretation of groundwater flow direction is given by the blue arrows.

6.6 Depth to watertable analysis – SW Cranbourne West The field investigation of this project focussed on the southern end of the Cranbourne West growth area where shallow watertables have been documented in preceding investigations in the area of bores GW4 and CW1 (SKM, 2005). This project confirmed the occurrence of shallow watertables. A map of the current depth to watertable (22 May 2007)) in this area is drawn using the approach described below with the intention of contributing to the planning process for Cranbourne West.

Firstly Figure 20 shows the land surface elevation at the southern end of Cranbourne West in metres AHD. Figure 21 is the estimated groundwater potential in metres AHD, this can be

Hall Rd.

Wester

n Port

High

way

5101520253035404550556065707580859095100

North

South




39

considered to be an approximate representation of the watertable surface.1 Note that the only data points contributing to this figure are at the marked groundwater observation bores and that the interpolated watertable surface is ‘stretched’ between these points. Figure 22 is the estimated depth to watertable, calculated as the difference between Figure 20 and Figure 21. Note that Figure 22 is a rough estimate of the depth to watertable and is strongly affected by the accuracy of Figure 21 with noted limitations of the simplicity of interpolation and the assumption that groundwater potential is equal to depth to watertable. In Figure 22 the areas mapped with depth to watertable less than 2 m can be considered to be areas that are ‘at risk’ of having shallow watertables even if they do not currently occur.

Figure 22 highlights a large area between groundwater bores CW1 and CW3 with a risk of shallow watertable (i.e. has a mapped depth to watertable less than 2 m). However, under current conditions it is unlikely that the land area immediately around groundwater bore CW3 would develop a shallow watertable because the bore is sited on a hillslope (Figure 20) and nearly 10 metres of clay overlie the sand aquifer at this bore (Figure 11). Rough estimates during drilling suggest that the watertable may occur at a depth of around 3 m in the clays. Further investigations are recommended to confirm the extent of the area at risk.

1 Figure 21 reflects the groundwater potentials observed in the sandy geological layers. In some bores the watertable will occur in the overlying near-surface clays and may not correspond with the potential in the sandy layers, however it is likely that the watertable will be influenced by the underlying groundwater potential.




40

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Figure 20. Land surface elevation (mAHD) at the SW corner of the Cranbourne West development. Groundwater observation bores are also marked.




41

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Figure 21. Reduced groundwater level (mAHD).




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Figure 22. Estimated depth to watertable (m) from land surface.




43

7. Conclusions

7.1 Overview In this section we draw on all sections of the report above to evaluate what the groundwater conditions are in and around the Cranbourne West site and how groundwater management might be integrated into the urban water cycle. In section 7.2 simple calculations are used to assess the volume of groundwater that may be able to be extracted at this site. In section 7.3 the water quality issues are summarised and in Section 7.4 we revisit the constraints analysis developed by SKM (2005).

Also relevant is the submission to Draft Precinct Plan which is attached as Appendix D.

7.2 Estimate of Sustainable Groundwater Yield Groundwater flow in the sand layer between bore CW3 and CW1 can be estimated in a simple calculation as presented in the table below.

Parameter Description Value Refer to b Thickness of sand layer (m) 15 m Figure 11 w Width across which groundwater flow is calculated (m) 500 m Figure 21 K Estimated hydraulic conductivity of the sand layer

(m/day) 2.5 m/day Table 5

dh/dz Estimated hydraulic gradient between CW3, CW4 and CW1 (m/m)

0.013 Figure 21

Q Groundwater flow in sand layer over 500 m width

Q = b×K×w×dh/dz 244 m3/day = 89 ML/year

Additional simple calculations can supplement our understanding. If it is assumed that groundwater recharge = 30 mm/year (recharge is water that drains below the vegetation root zone and reaches the watertable), then maintaining the estimated groundwater flow of 89 ML/year would require recharge from an area of about 270 hectares or 2.7 km2. This is a large contributing area for a shallow groundwater system and suggests that if our estimates are correct the sand layer would be receiving most of its recharge from outside the Cranbourne West development area. The implication is that groundwater conditions in the SW Cranbourne West are impacted by the broader catchment to the south east over which the Cranbourne West development has no control.

These calculations are rough and rely on very approximate measurements of aquifer hydraulic conductivity. The estimated groundwater flow of 89 ML/year can only be considered to be an order of magnitude estimate because all of the input parameters have associated uncertainties and the groundwater potentials were all measured on one date with no long term confirmation of




44

observations. However, the calculations indicate that groundwater extraction of 20 ML/year or more may be feasible at this site and further field investigation is warranted to confirm the current estimates.

Limitations on the accuracy of the calculation exist, however it indicates that it is possible a reasonable groundwater volume may be able to be extracted at this site and that further investigations/confirmation may be warranted.

If it is required to permanently lower groundwater levels in and around the area of shallow watertables then large volumes of groundwater (perhaps > 89 ML/year) may need to be extracted and disposed of. The nature of current groundwater discharge from the catchment under existing conditions also needs to be considered further (e.g. are there groundwater dependent ecosystems down gradient).

7.3 Water Quality Analysis and Potential Use of Groundwater The bore sampling has provided a snapshot of the groundwater quality in the south western sector of the Cranbourne West urban growth area. Nevertheless, there are enough data to be able to draw some conclusions about the suitability of the groundwater for use in the Cranbourne West urban development. These conclusions were provided by Wendy van Dok, City of Casey.

The absence of detectable pesticides and very low E.coli levels mean the groundwater is likely to suitable for non-potable uses with uncontrolled public access e.g. public space irrigation.

The water quality is generally good with the exception of salinity, sodium and SAR which limits its suitability for landscape irrigation and drinking unless it is treated or perhaps diluted with roofwater or stormwater to bring the SAR down below 5. Alternatively, or in addition to creating a shandy, if a specially structured media was used instead of clay soil for sports fields, and the water was self contained i.e. confined within a geofabric layer, it could conceivably be used for turf irrigation providing a salt tolerant species was used.

Given the volume of groundwater available for extraction is likely to be low, one potential use of the groundwater is a mineral spa. Saltwater pools typically have a TDS level between 4,000 mg/L and 7,000 mg/L and while the groundwater samples indicate salinity well below these levels, it would not prevent the groundwater from being used for a spa. It could also be used for a salt tolerant hydroponic horticulture scheme.

The potential yield of groundwater in the shallow water table region is estimated to be about 20 to 80 ML (20 mega litres) per year. At this stage, there are 4 sports fields planned for Cranbourne West. One sports field needs about 4 ML/year of irrigation water so an obvious match in terms of volume would be to use groundwater for sports field irrigation. If the groundwater was undiluted then there would need to be some very specific design elements incorporated into the irrigation scheme to prevent soil degradation, i.e. a very salt tolerant




45

species like Kikuyu would need to be used, a suitable media should be created in which to grow the turf because clay should be avoided and it should be a self contained system with subsurface water drainage/storage cells and be lined with a geofabfric. For example see the Atlantis system http://www.atlantiscorp.com.au/applications. How the water would be extracted, from which site, and what infrastructure would be needed for such a scheme would need to be determined.

7.4 Groundwater Constraints to Urban Development The groundwater constraints investigation (SKM, 2005) considered a large area extending from Cranbourne West and Dandenong at the western edge to Bunyip in the east. Most of this area lies within the Westernport Basin and has large upstream catchments that can affect the water balance and the watertable at any site. The method used by SKM (2005) was intended to be applied at a regional scale and necessarily made some generalisations about the nature of groundwater systems.

In contrast to the larger region, the Cranbourne West site lies in a small catchment with a small upstream area that drains to Port Phillip Bay. The groundwater systems are local (not significantly affected by regional groundwater flow) and generally of low permeability with the exception of isolated sand lenses. Subject to further investigation, it is considered that the risks to urban development are likely to be managed relatively easily at the Cranbourne West site and may not be as severe as described by SKM (2005).

SKM (2005) integrated the following components using a Geographical Information System:

Likelihood of occurrence of a shallow watertable above a critical depth;

Groundwater salinity ; and

Soil type – there were 2 types considered, sandy soils and clay-rich soils with different critical depths to watertable.

The integration of these components was used to produce a development constraint map for shallow groundwater conditions. The likelihood of occurrence was evaluated using an analysis of groundwater levels extrapolated to a 100 year period. Likelihood of a watertable rising higher than the critical level was evaluated for the 100 year period.

Obviously the data available to this study do not allow us to estimate the expected length of time that a watertable would exceed the critical levels over a 100 year period in the SW corner of the Cranbourne West growth area. Nevertheless, visual evaluation of Figure 20, Figure 21 and Figure 22 and consideration of the hydrogeological conceptual model of the area in the south west allows us to estimate where ‘Risk Category 5: Not Recommended for Urban Development’ is most likely to occur. The extent of the area is sketched out in Figure 23 below and is likely to include areas that would be classified in Risk Category 5 or Risk Category 4 (Development Severely Constrained).




46

We understand that a retarding basin for stormwater will be constructed in the middle of the hatched area (Figure 23). Control of shallow watertables around the basin may be necessary depending on the basin design and surrounding land uses. Management of this retarding basin could include, and the basin itself may provide an opportunity to enhance groundwater supply by allowing or promoting leakage from the basin. in the As this area is expected to have a shallow watertable

Table 7 and Table 8 below have been copied from SKM (2005) to emphasize the types of constraints that development at Cranbourne West may need to consider.




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Figure 23. Approximate area that is likely to be considered to be “not recommended for

urban development” or “severely constrained” as described by SKM (2005): shown as the hatched area on a land surface elevation map. It is understood that a stormwater retention basin will be constructed in the central part of this area.




The tables below have been re-produced from the report ‘Watertable constraints to Urban Development’ SKM(2005). Table 7 and Table 8 below appeared as Table 4 and Table 12 in SKM(2005).

Table 7. Constraint categories defined for the Casey-Cardinia growth area.

Category Constraint category (and summary)

Expanded definition Impacts for Developer

Impacts for Local Authority

Impacts for Utilities Companies

Impacts for Property owner

1 No significant constraints. Costs for development and management to attain amenity and function of a non-shallow watertable affected area are comparable.

Shallow watertable are not likely to occur with the exception of small, localised areas associated with local soils types and geology. Construction and management of urban infrastructure not dictated by shallow watertables.

None None None None

2 Constrained – some design and construction measures may be necessary based on existing building and site development standards. Residential housing and associated gardens will require some additional protection measures. Principal costs to maintain function and amenity are up front. Ongoing management and maintenance should not differ from non-shallow watertable affected areas.

Shallow watertables may occur in the lifespan of the development. Built structures and services should be designed with materials that are resistant to period of emersion in groundwater for varying lengths of time at site specific salinities. Vegetation types should be selected with tolerance to wet soil conditions, and specific to the salinity of the groundwater that is likely to be encountered. The management options applied are considered to be low maintenance in the long term and will not require specific management plans or operation and maintenance costs. The focus is on materials and plant species designed to cope with conditions.

Capital cost of construction

Minimal additional cost



3 Highly Constrained – urban development will require significant

Persistence or salinity of shallow watertables will require engineering to resist long periods


Ongoing maintenance


Specific management of




49

additional cost in the design and construction phase, as well as specialised management approaches to maintain function and amenity. Commercial developments will need to consider engineering of structures and selective use of gardens, but are generally less constrained than residential.

or aggressive groundwater conditions. Preference is on the use of construction materials and approaches to resist the watertable conditions, although additional engineered measures are likely to be required. In addition to construction material and techniques and species selection, active engineering options that will require operation and maintenance such as drainage systems, raising of garden beds, specialist irrigation systems, and groundwater pumping. Substantial additional costs required at construction with ongoing maintenance and operation

Operation over covenant period.

and operation of engineered systems. If not engineered, infrastructure could be expected to have a reduced lifespan of up to 20%.

Ongoing maintenance and operation of engineered systems. If not engineered, infrastructure could be expected to have a reduced lifespan of up to 20%.

garden areas and species to be grown. If not engineered, infrastructure could be expected to have a reduced lifespan of up to 20%. Possible increased maintenance costs of built structures.

4 Severely constrained – Design, construction and operation of built structures, infrastructure, domestic gardens and open space will require specialised engineering of materials, construction approaches and the likely incorporation of active engineering options to manage persistent shallow watertables. To maintain function and amenity, significant additional operational effort and cost will be incurred. Residential development severely constrained. As function and amenity requirements of commercial areas are lower, these areas are considered highly constrained.

Persistent and aggressive shallow groundwater conditions requiring intensive active engineering systems on top of material and species selection criteria. Drainage systems and groundwater pumping approaches are required to be maintained and operated for the protection of built structures and infrastructure for the majority of the time. Garden areas require specific management through the use of raised and tanked garden beds and irrigation and drainage systems.

Capital cost of construction Operation over covenant period.


Capital cost of construction Ongoing maintenance and operation of engineered systems. If not engineered, infrastructure could be expected to have a reduced lifespan of up to 50%.

Specific management of garden areas and species to be grown. If not engineered, infrastructure could be expected to have a reduced lifespan of up to 50%. Possible increased maintenance costs of built structures.

5 Not recommended for urban development. Active engineering would be required continuously to manage watertable levels to provide function, although amenity is still anticipated to be significantly impact.

Effectively continuous persistence of shallow watertables. Costs to manage are at all stages of the project, and are now such that viability even in construction phase may be compromised.


Ongoing maintenance and operation of engineered systems. If not engineered, infrastructure could be expected to

Capital cost of construction Ongoing maintenance and operation of engineered systems. If not engineered, infrastructure

Specific management of garden areas and species to be grown. If not engineered, infrastructure could be expected to have a reduced lifespan in excess of 50%.




50

have a reduced lifespan in excess of 50%.

could be expected to have a reduced lifespan in excess of 50%.

Possible increased maintenance costs of built structures.

Table 8 Summary of definitions of constraint as applied to different land uses in an urban setting

Risk Category

Risk Definition Urban Residential Built Structures and Services

Commercial Built Structures and Services Open Space / Domestic Gardens

1 No significant constraints on Urban Development

Shallow Watertables not likely to impact land use

2 Constrained Impacts at construction phase. Additional cost in longer term management expected to be minimal.

Use of materials and design measures to mitigate impacts of shallow watertables and associated salinity. No ongoing additional cost for operation and maintenance.


Management of impacts based around selection of plants with slightly higher salt tolerance. Once selected and planted, no additional specific management required.

3 Highly Constrained Substantial engineering required in construction phase, with some additional operation and maintenance cost throughout lifespan..

Buildings, foundations, roads and infrastructure require use of materials and design measures to mitigate impacts of shallow watertables and associated salinity. Protection of built structures by use of fill (up to 0.5m) and may include perimeter and sub-surface drainage to protect specific assets. Sub-surface structures require tanking or drainage to protect. Increased effort and cost required to operate and maintain drainage and other specific engineering management approaches.


Selection of groundcover species to be resistant to the local groundwater now required. Use of fill or drainage in open space and domestic gardens more likely. Raising of flowerbeds recommended to protect low salt tolerant species over the lifespan of the development. Specialised irrigation management likely in years when watertable is shallow.

4 Severely Constrained Substantial cost in the construction phase and in ongoing operation and maintenance of management systems required to provide

Buildings, foundations, roads and infrastructure require use of materials and design measures to mitigate impacts of shallow watertables and associated salinity. Protection of built structures by use of fill (up to 1.0m) and likely to include perimeter and sub-surface drainage to protect specific assets. Sub-surface structures require

Buildings, foundations, roads and infrastructure require use of materials and design measures to mitigate impacts of shallow watertables and associated salinity. Protection of built structures by use of fill (up to 1.0m) and likely to include perimeter and sub-surface drainage to protect specific

Selection of groundcover species to be resistant to the local groundwater now required. Use of fill or drainage in open space and domestic gardens required. Raising or tanking of flowerbeds and stands for shrubs and trees now required. Use of sub-surface drainage under any areas where groundcover




51

Risk Category



function. tanking or drainage to protect. Roads and service infrastructure likely to require specific drainage (either deep surface drains, sub-surface drains or groundwater pumping) to maintain function. Significant additional effort and cost required to operate and maintain drainage and other specific engineering management approaches.

assets. Sub-surface structures require tanking or drainage to protect. Roads and service infrastructure likely to require specific drainage (either deep surface drains, sub-surface drains or groundwater pumping) to maintain function. Significant additional effort and cost required to operate and maintain drainage and other specific engineering management approaches.

establishment is important. Ongoing selection of salt tolerant species, and increased management of parks, open space and domestic gardens required. Irrigation scheduling now critical. Unlikely to be suitable for sporting based recreation reserves.

5 Not Recommended for Urban Development # Costs and impacts unacceptable for use of land as an urban development.

Buildings, foundations, roads and infrastructure require use of materials and design measures to mitigate impacts of shallow watertables and associated salinity. Protection of built structures by use of fill (greater than 1.0m) and /or perimeter and sub-surface drainage to protect specific assets. Sub-surface structures require tanking or drainage to protect. Roads and service infrastructure likely to require substantial elevation and specific drainage (either deep surface drains, sub-surface drains or groundwater pumping) to maintain function. Prohibitive additional effort and cost required to operate and maintain engineering management approaches.


Limited long term prospect for successful plantings, high risk to investment in landscaping asset and high likelihood of significant maintenance costs and/or extensive engineering works. All flowerbeds, tree and shrub plantings in raised or tanked beds. Groundcover plants only likely to be those tolerant to waterlogged and/or high salinity watertable. Management of open space and gardens highly intensive. Unsuitable for sporting based recreation reserves.

# Site specific groundwater investigations required accompanied with an engineering response report



7.5 Shallow Watertables: Threats, Causes and Management Options at Cranbourne West

The current catchment conditions do not appear to preclude any current land use within Cranbourne West (e.g. residential dwellings are present and the Westernport Highway runs along the western edge of the area close to areas of shallow watertable). Furthermore, guidelines for appropriate construction of buildings, roads, and services exist for a range of different environments (including shallow saline watertables – for examples see Western Sydney and Wagga Wagga).

However, the catchment hydrology will change with development of Cranbourne West and in areas currently with a shallow watertable it is recommended that development aims to avoid land uses/management that could promote or create shallow watertable conditions (see Table 9). Figure 13 and Figure 22 show two areas with a mapped watertable at a depth of less than 2 m that are likely to require special planning consideration with regard to shallow watertable conditions.

Table 9 summarises the threats, causes and management options for areas likely to have shallow watertables.

Table 9. Table of threats, causes and management options.

Threat: Shallow watertables resulting in: waterlogging, land salinisation (in the long term), reduced life span of foundations/roads/services

Potential causes: Shallow watertables in the South West of the Cranbourne West site are considered to be the result of groundwater flow converging in an area with restricted groundwater flow out of the area. The Cranbourne West development should avoid increasing net groundwater flow into this area. Factors to consider include the following:

irrigation of urban gardens, runoff from impervious surfaces increasing infiltration in some areas, leakage of reticulation system (the risks of leakage are likely to increase

with the presence of an additional ‘third pipe’ system). Pre-emptive management options

minimise risks of increased net groundwater recharge non-residential land use increased tree canopy cover reticulation systems constructed to higher standard within these

areas to minimise leakage install subsurface drainage system use area as ‘green space’ with high tree canopy cover or other ‘low net

recharge’ option (possibly an impervious surface with subsurface drains) extraction and use of groundwater within development



In discussion with The City of Casey three approaches to manage land prone to shallow water tables were discussed. They vary in capital cost, net gain for the environment, financial benefit to the land owners and requirements for long term maintenance of assets like pumps and bores.

The three indicative approaches are as follows.

1) Adopt passive land uses which do not require any intervention for management of groundwater e.g. public open space with large deep rooted trees suited to the conditions. This option will have the most net gain for the environment as it will create habitat and green space but it will mean the loss of developable land. It would need to be integrated with the proposed retarding basin.

2) Undertake active intervention so that houses can be built on the site. This might involve a scheme where groundwater is extracted and discharged offsite, the nature of discharge or disposal would require additional investigation. Alternatively, the land surface could be raised to make the land more suitable for housing. Either way practices that are known to increase the risk of urban salinity would need to be avoided like over-irrigation, leaking water infrastructure, increased stormwater infiltration. This will be an expensive option with little if any, net gain for the environment but it will deliver developable land for the owners. There will however need to be a high level of design civic compliance to avoid the high risk practices like over irrigation. The proposed retarding basin would need to be sealed to minimise or avoid infiltration.

3) Active intervention with groundwater use where the water table is managed with an integrated groundwater/stormwater scheme. This could involve locating and constructing a retarding basin that facilitated infiltration into the aquifer to increase the reliability of groundwater supply within the urban development. This would mean the land could still be developed and there would be some net gain to the environment in terms of using the groundwater to offset the need for reticulated mains water. There are likely to be high capital and ongoing maintenance costs. Potential uses for the groundwater have been discussed in Section 7.3.

7.6 Meeting Smart Water Fund Objectives To summarise, for the purposes of fulfilling the stated objective of this Smart Water Fund project the research:

has confirmed that shallow water tables exist and that they pose a risk to conventional development in Cranbourne West;

has investigated the feasibility of using groundwater in the development as a way to manage the shallow water table (we have investigated the nature of the groundwater system and the groundwater quality and estimated a groundwater flow rate);



indicates that an integrated stormwater and groundwater scheme could provide the desired outcome of managing the groundwater as part of the solution rather than the cause of the problem.

Within this project there have been two submissions to the Cranbourne West Growth Area planning team:

a specialist report “Groundwater and Salinity Issues in the Cranbourne West Growth Area”; and

a submission in response to the Draft Precinct Plan (included as Appendix D)



8. Ongoing Monitoring and Future Investigations

8.1 Ongoing Groundwater Monitoring Regular and continuing monitoring of groundwater conditions in critical locations would improve understanding of the groundwater system and provide warning of rising watertables. At the outset it would be good to monitor groundwater levels once every two months with a re-assessment of the frequency of measurement required after 3 or 4 monitoring events.

8.2 Future Groundwater Investigations Appropriate work to follow on from this investigation would be dependent on the aims of proposed management. For example, is it required to:

a) further characterise and delineate existing groundwater conditions in the south west corner and associated risks; OR

b) test options for groundwater extraction and ‘active’ groundwater management in the area the chosen approach.

In case a) above the next step might be: Construction of two or three additional shallow observation bores (to 15 m) at the current

Anco Turf farm.

In case b) the next step could be to:

Undertake a pump test of the aquifer to refine understanding of aquifer properties and investigate the likely long term extraction limit for groundwater (this would require construction of a new groundwater bore for extraction and then continuous pumping of groundwater and monitoring of surrounding groundwater levels for approximately one month);

Other relevant groundwater investigation work that might be considered is as follows.

Design a potential groundwater ‘interception’ scheme. It may be appropriate to install a spear-point well system that uses one pump to extract groundwater from several shallow groundwater bore holes.

Development of a plan for conjunctive management of the proposed stormwater retention basin and the extraction of groundwater (this may include enhancement of leakage from the basin to groundwater).

Summarise potential groundwater uses and necessary infrastructure (e.g. irrigation of playing fields, provision of water to other amenities) if it is decided to extract groundwater in the SW



corner of Cranbourne West (note that groundwater extracted need not be used precisely at the site of extraction, it is often feasible to pump the water to the site where it is required);

Investigation of the groundwater quality for proposed use including treatments required to reduce the sodium adsorption ratio and to change any other water quality parameters that don’t meet requirements of proposed water use;

Investigate where groundwater discharge from the area of SW Cranbourne West is currently discharging: is it contributing to stream baseflow, is it supporting a wetland ecosystem, or is it discharging to Port Phillip Bay?

Development of a groundwater model to test scenarios of groundwater extraction and management and their likely effects on the depth to watertable in the SW Cranbourne West area.

We would be happy to provide more details of any of these tasks once the priorities of developers have been discussed.



9. References

Dahlhaus et al., 2004. Port Phillip and Westernport Groundwater Flow Systems. Port Phillip and Westernport Catchment Management Authority, Melbourne, Victoria.

DCNR, 1995. Victorian Groundwater Beneficial Use Map Series, South Western Victoria Water Table Aquifers.

Ecological Engineering, 2006. Water Sensitive Urban Design: Cranbourne West. Draft paper submitted to City of Casey.

GHD, 2006. Phase 1 Environmental Assessment: Cranbourne West. Draft paper submitted to City of Casey.

Geological Survey of Victoria, 1971. Queenscliff 1:250,000 Geological Map.

Lane Consulting, 2005. Hydrogeological assessment report, 570 Hall Road, Cranbourne West.

Sinclair Knight Merz (SKM), 2005. Shallow watertable constraints on urban development. Melbourne 2030, Department of Sustainability and Environment, Victoria.

Sinclair Knight Merz (SKM), 2007. Cranbourne West Urban Growth Plan: Groundwater and Salinity, Stage 1. Draft Specialist Report to City of Casey.



Appendix A Bore Logs of Geological Strata

(very soft)(soft)(firm)(stiff)(very stiff)(hard)

soil type, unified classification, colour, structure,particle characteristics, minor components

sam

ple

type

D = Dry M = Moist W = Wet

Aqua Drilling and Grouting

= Undisturbed Tube Sample

MOISTURE CONDITION

LAB DATA

Logged:Checked:

= SPT Spoon Sample (Pushed)

odou

rra

nkin

gdrilling method, wellconstruction, water

and additionalobservations

W

W

W

50mm

grou

nd w

ater

PID

(ppm

)

Driller:Rig:Surface Conditions:

City of Casey

SK

M E

NV

1 V

W03

861_

BO

RE

LOG

S.G

PJ

SK

M_E

NV

L1.G

DT

5/2

8/07

BOREHOLE No. CW1

= Disturbed Sample

visu

alra

nkin

g

sam

ple

ID

moi

stur

e co

nten

t(%

)

07/05/07 - 07/05/07

FIELD DATA

SuvSupNFPMPID

W

W

As above

Clayey SAND: Light grey, medium to coarse grain.Minor clay

Clayey SAND: Grey with medium grain sand

Sandy CLAY: Orange clay with fine grained sand.

Silty CLAY: Grey to blue grey clays with minor silts.

CLAY: Grey-brown mottled orange, firm clays withminor sands (<10%).

Silty SAND: Orange, fine to medium grain. Someorganic material. Some dark brown grains, easy tobreak with fingernail

As above

Surface: Topsoil including organic material

Cranbourne West DrillingCranbourne WestVW04032

W

W

M

D

D

Clayey SAND: Orange medium to coarse grain.Some red oxidised medium size grains

W

Silty SAND: Orange, becoming finer

Northings:Eastings:RL:

ODOUR RANKING

No visible evidence of contaminationSlight visible contaminationVisible contaminationSignificant visible contamination

field

test

s

COMMENTS

moi

stur

eco

nditi

on

dry

dens

ity(t/

m )

VLLMDDVDCO

0123

Sheet

Project:Location:Job No:

KKGM

DENSITY (N-value)

5779717.11 mN345193.83 mE

Grassed

1

2

3

4

5

6

7

8

9

10

SOILCONDITION

= Shear vane test

grap

hic

log

(very loose)(loose)(medium dense)(dense)(very dense)(compact)

1

dept

h (m

)

of

<1010 - 2020 - 3030 - 50>50>50/150mm

Client:Start - Finish Date:Bore dia:

SOIL DESCRIPTION

= Bulk Sample

VSSFStVStH

CONSISTENCY (Su)

field

test

s

< 12 kPa12 - 2525 - 5050 - 100100 - 200> 200 kPa

cons

iste

ncy/

dens

ity

= Pocket Penetrometer test

4

= Outflow / Inflow

3

= Standard Penetration Test (SPT top = start of N blowcount)

= Uncorrected vane shear (kPa)= Pocket penetrometer (kPa)= SPT blows per 300mm= Field permeability= Photoionisation detector reading (ppm, V/V)

= Water level (during drilling)= Water level (static)GROUNDWATER SYMBOLS

FIELD DATA ABBREVIATIONS

No Non-Natural odoursSlight Non-Natural odoursModerate Non-Natural odoursStrong Non-Natural odours

ABCD

VISUAL RANKING FIELD DATA SYMBOLS

07/05/07 - 07/05/07

FIELD DATA

SuvSupNFPMPID

sam

ple

ID

visu

alra

nkin

g

sam

ple

type




MOISTURE CONDITION

50mmLogged:Checked:

field

test

s


BOREHOLE No. CW1

< 12 kPa12 - 2525 - 5050 - 100100 - 200> 200 kPa

SK

M E

NV

1 V

W03

861_

BO

RE

LOG

S.G

PJ

SK

M_E

NV

L1.G

DT

5/2

8/07


LAB DATAP

ID(p

pm)



0123

= Disturbed Sample

grou

nd w

ater

moi

stur

e co

nten

t(%

)


City of Casey

As above

Sandy SILT: Fine - medium grain quartz, gritty

Silty SAND: Smaller % of sands, becoming siltier.Red mottled sandy inclusions

Silty SAND: Orange-brown, Fine to medium grain.Dark red to red-brown sandy inclusions

As above: Some dark brown-red grains, easily broken

As above: Medium grain


Silty SAND: Orange, becoming finer (continued)

Sandy SILT: Orange brown, fine grain W

odou

rra

nkin



W

W

W

W

W

Silty SAND & Grey Clayey SAND: Mottled orangeand grey

W

cons

iste

ncy/

dens

ity

W

KKGM

SOILCONDITION


COMMENTS

moi

stur

eco

nditi

on



= Shear vane test

field

test

s

DENSITY (N-value)

5779717.11 mN345193.83 mE

Grassed

11

12

13

14

15

16

17

18

19

20

dry

dens

ity(t/

m )

grap

hic

log


2

dept

h (m

)

Sheet of

SOIL DESCRIPTION

FIELD DATA SYMBOLSVLLMDDVDCO

VISUAL RANKING

3

4

<1010 - 2020 - 3030 - 50>50>50/150mm

= Bulk Sample

VSSFStVStH

CONSISTENCY (Su)= Uncorrected vane shear (kPa)= Pocket penetrometer (kPa)= SPT blows per 300mm= Field permeability= Photoionisation detector reading (ppm, V/V)ODOUR RANKING



ABCD

= Water level (static)

= Outflow / Inflow


= Water level (during drilling)


GROUNDWATER SYMBOLS

BOREHOLE No. CW1

0123

= Disturbed Sample

sam

ple

ID

moi

stur

e co

nten

t(%

)


07/05/07 - 07/05/07

FIELD DATA

SuvSupNFPMPID

SK

M E

NV

1 V

W03

861_

BO

RE

LOG

S.G

PJ

SK

M_E

NV

L1.G

DT

5/2

8/07

grou

nd w

ater

< 12 kPa12 - 2525 - 5050 - 100100 - 200> 200 kPa

4

<1010 - 2020 - 3030 - 50>50>50/150mm

= Bulk Sample

VSSFStVStH

CONSISTENCY (Su)


field

test

s

City of Casey

cons

iste

ncy/

dens

ity



LAB DATAP

ID(p

pm)

visu

alra

nkin

g

GRAVEL: Grey, large angular fragments (up to 1cm)in silt

W

As above: Yellow grey. Silt content increasingamongst large gravel fragments

W

Silty SAND and Sandy CLAY: Orange, and grey, fineto medium grain. Small gravel fragments

Silty SAND & Grey Clayey SAND: Mottled orangeand grey (continued)

Silty SAND: Grey silt and orange sand

Logged:Checked:


sam

ple

type




W

50mm

W



odou

rra

nkin



MOISTURE CONDITION

dry

dens

ity(t/

m )

SOILCONDITION


SOIL DESCRIPTION

dept

h (m

)

field

test

s

COMMENTS

KKGM

moi

stur

eco

nditi

on

5779717.11 mN345193.83 mE

Grassed

of

DENSITY (N-value)

grap

hic

log


3

VLLMDDVDCO

21

22

23

24

25

26

27

28

29

30

3

GROUNDWATER SYMBOLS



ABCD

VISUAL RANKING


FIELD DATA SYMBOLS



Sheet

= Shear vane testFIELD DATA ABBREVIATIONS

ODOUR RANKING

= Outflow / Inflow



< 12 kPa12 - 2525 - 5050 - 100100 - 200> 200 kPa

grou

nd w

ater

= Disturbed Sample

0123

BOREHOLE No. CW1


City of Casey Driller:Rig:Surface Conditions:

PID

(ppm

)LAB DATA


cons

iste

ncy/

dens

ity

field

test

s

CONSISTENCY (Su)VSSFStVStH

= Bulk Sample

<1010 - 2020 - 3030 - 50>50>50/150mm

4

SOIL DESCRIPTION



Silty SAND: Grey silt and orange sand (continued)

SILT: Dark grey-brown, some orange silt

Borehole Terminated at 31.50 mbgl.

W

drilling method, wellconstruction, water


odou

rra

nkin

g



Logged:Checked:

moi

stur

e co

nten

t(%

)

visu

alra

nkin

g


07/05/07 - 07/05/07

FIELD DATA

SuvSupNFPMPID

50mm

sam

ple

ID

MOISTURE CONDITION


sam

ple

type



4

moi

stur

eco

nditi

on

COMMENTS

field

test

s


SOILCONDITION

dry

dens

ity(t/

m )

SK

M E

NV

1 V

W03

861_

BO

RE

LOG

S.G

PJ

SK

M_E

NV

L1.G

DT

5/2

8/07

of

5779717.11 mN345193.83 mE

Grassed

31

32

33

34

35

36

37

38

39

40

dept

h (m

)

DENSITY (N-value)

grap

hic

log



3

FIELD DATA SYMBOLSVISUAL RANKING

ABCD



GROUNDWATER SYMBOLS= Water level (static)= Water level (during drilling)

= Outflow / Inflow

KKGM

VLLMDDVDCO

Sheet

= Shear vane test

ODOUR RANKING



sam

ple

ID

MOISTURE CONDITION

08/05/2007 - 09/05/2007

FIELD DATA

grou

nd w

ater

visu

alra

nkin

g


sam

ple

type


Aqua Drilling

VSSFStVStH

SuvSupNFPMPID

PID

(ppm

)

SK

M E

NV

1 V

W03

861_

BO

RE

LOG

S.G

PJ

SK

M_E

NV

L1.G

DT

5/2

8/07

< 12 kPa12 - 2525 - 5050 - 100100 - 200> 200 kPa

cons

iste

ncy/

dens

ity


moi

stur

e co

nten

t(%

)

LAB DATA

50mm


City of CaseyCranbourne West DrillingCranbourne WestVW04032

BOREHOLE No. CW2

0123

= Disturbed Sample



Weathered BASALT: Chips of basalt up to 3cm insize.

Water table encountered at 8.0mbgl.

Dark basalt fragments with increasing moisture.

CLAY: Light grey clays with dark grey/black blackfragments.

As above except with small fragments of basalt.

Silty CLAY: Brown, dry clays.

SURFACE: Dark brown/black topsoil material withorganic matter and clay constituents.

SILT: Yellow brown silts; dry and friable.

M

Logged:Checked:



odou

rra

nkin



BASALT: Fine grey basalt chips.

W

CONSISTENCY (Su)

M

D

D

D

W

COMMENTS

= Shear vane test

SOILCONDITION


field

test

s

KKGM

moi

stur

eco

nditi

on


field

test

s

= Bulk Sample

5780595.43 mN345206.3 mE

Grassed

dry

dens

ity(t/

m )

ofSheet

DENSITY (N-value)

grap

hic

log


1

dept

h (m

)

1

2

3

4

5

6

7

8

9

10

VISUAL RANKINGVLLMDDVDCO

FIELD DATA SYMBOLS

3


ABCD

SOIL DESCRIPTION

3

<1010 - 2020 - 3030 - 50>50>50/150mm


ODOUR RANKING


FIELD DATA ABBREVIATIONS= Uncorrected vane shear (kPa)= Pocket penetrometer (kPa)= SPT blows per 300mm= Field permeability= Photoionisation detector reading (ppm, V/V)

= Outflow / Inflow= Water level (during drilling)= Water level (static)GROUNDWATER SYMBOLS

grou

nd w

ater

moi

stur

e co

nten

t(%

)

08/05/2007 - 09/05/2007Aqua Drilling

SuvSupNFPMPID

= Disturbed Sample

sam

ple

ID

visu

alra

nkin

g


sam

ple

type

SK

M E

NV

1 V

W03

861_

BO

RE

LOG

S.G

PJ

SK

M_E

NV

L1.G

DT

5/2

8/07

FIELD DATALAB DATA

VSSFStVStH

field

test

s

< 12 kPa12 - 2525 - 5050 - 100100 - 200> 200 kPa

cons

iste

ncy/

dens

ity


PID

(ppm

)



BOREHOLE No. CW2

0123



CLAY: Brown clays, very wet (mud like consistency).

CLAY: Grey/brown clays, high plasticity, no rockfragments present.

CLAY: Grey/brown clays with some grit, highplasticity.

BASALT: Grey clays (Weathered Basalt) with smallbasalt fragments.

BASALT: Grey/blue grey basalt chips with 50% clay.


BASALT: Grey basalt chips (gravel size <1cm).

BASALT: Grey basalt chips with increasing claycontent.

W

MOISTURE CONDITION

50mmLogged:Checked:





W

W

W

W

W

W

= Bulk Sample

odou

rra

nkin

g

COMMENTS

dry

dens

ity(t/

m )

SOILCONDITION


<1010 - 2020 - 3030 - 50>50>50/150mm

field

test

s

KKGM

moi

stur

eco

nditi

on


CONSISTENCY (Su)

5780595.43 mN345206.3 mE

Grassed

of

DENSITY (N-value)

grap

hic

log


2

dept

h (m

)

Sheet

11

12

13

14

15

16

17

18

19

20

= Shear vane test

ABCD

VLLMDDVDCO

FIELD DATA SYMBOLS

3




SOIL DESCRIPTION

3

ODOUR RANKING

VISUAL RANKING


GROUNDWATER SYMBOLS


= Outflow / Inflow= Water level (during drilling)= Water level (static)

= Disturbed Sample

0123

BOREHOLE No. CW2



PID

(ppm

)LAB DATA



cons

iste

ncy/

dens

ity

field

test

sgr

ound

wat

er


= Bulk Sample

<1010 - 2020 - 3030 - 50>50>50/150mm

3

SOIL DESCRIPTION

< 12 kPa12 - 2525 - 5050 - 100100 - 200> 200 kPa


CLAY: Brown clays intermingled with quartz gravels.

Borehole Terminated at 23.0 mbgl and wellconstructed.

W



odou

rra

nkin

g



Logged:Checked:50mm

MOISTURE CONDITION

Aqua Drilling3

sam

ple

type soil type, unified classification, colour, structure,

particle characteristics, minor components

visu

alra

nkin

g

sam

ple

ID

SuvSupNFPMPID

FIELD DATA

08/05/2007 - 09/05/2007m

oist

ure

cont

ent

(%)


3


COMMENTS

field

test

s


SOILCONDITION

dry

dens

ity(t/

m )

moi

stur

eco

nditi

on

dept

h (m

)



grap

hic

log

DENSITY (N-value)

of

21

22

23

24

25

26

27

28

29

30

Grassed

5780595.43 mN345206.3 mE



ABCD




= Outflow / Inflow

KKGM

VLLMDDVDCO

SheetS

KM

EN

V 1

VW

0386

1_B

OR

ELO

GS

.GP

J S

KM

_EN

VL1

.GD

T 5

/28/

07

ODOUR RANKING


= Shear vane test

09/05/2007 - 09/05/2007

FIELD DATA

SuvSupNFPMPID

sam

ple

ID

visu

alra

nkin

g

field

test

ssa

mpl

e ty

pe


Aqua Drilling


MOISTURE CONDITION

50mmLogged:Checked:



BOREHOLE No. CW3

< 12 kPa12 - 2525 - 5050 - 100100 - 200> 200 kPa

cons

iste

ncy/

dens

ity

SK

M E

NV

1 V

W03

861_

BO

RE

LOG

S.G

PJ

SK

M_E

NV

L1.G

DT

5/2

8/07


PID

(ppm

)



0123

= Disturbed Sample

grou

nd w

ater

moi

stur

e co

nten

t(%

)

odou

rra

nkin

g

City of Casey

SANDS: Yellow-brown sands in a clay matrix withcoarse sands.

Colour change to light grey clays and slightly coarsersands.

As above, with an increasing proportion of coarsesands present.

Silty CLAY: Silty clays <10% coarse grained sands.

CLAY: Orange mottled grey firm clays, highly plastic.

CLAYEY SAND: Orange and grey mottled clayeysmixed with fine grained sands.

SURFACE: TOPSOIL: Topsoil including someorganic matter.SAND: Brown sands, medium grained.

D




M

M

M

M

M

Sandy CLAY: Yellow-grey clays.

M


D

M

KKGM

SOILCONDITION


COMMENTS

moi

stur

eco

nditi

on


LAB DATA

= Shear vane test

field

test

s

DENSITY (N-value)

mN mE

Grassed

1

2

3

4

5

6

7

8

9

10

dry

dens

ity(t/

m )

grap

hic

log


1

dept

h (m

)

Sheet of

SOIL DESCRIPTION

FIELD DATA SYMBOLSVLLMDDVDCO

VISUAL RANKING

3

4

<1010 - 2020 - 3030 - 50>50>50/150mm

= Bulk Sample

VSSFStVStH

CONSISTENCY (Su)= Uncorrected vane shear (kPa)= Pocket penetrometer (kPa)= SPT blows per 300mm= Field permeability= Photoionisation detector reading (ppm, V/V)ODOUR RANKING



ABCD


= Outflow / Inflow




GROUNDWATER SYMBOLS

cons

iste

ncy/

dens

ity

moi

stur

e co

nten

t(%

)

grou

nd w

ater

= Disturbed Sample

0123

BOREHOLE No. CW3



PID

(ppm

)LAB DATA

= Bulk Sample

SOIL DESCRIPTION

4


<1010 - 2020 - 3030 - 50>50>50/150mm

= Pocket Penetrometer testVSSFStVStH

CONSISTENCY (Su)

field

test

s

< 12 kPa12 - 2525 - 5050 - 100100 - 200> 200 kPa

50mm

Sandy CLAY: Yellow-grey clays. (continued)

Silty CLAY: Grey silty clays mottled orange.

SAND: Coarse sands, minor grey and orange clayinterbedded between the coarse sands.

Lays of organic dark black peat present.

M

M



odou

rra

nkin

g


sam

ple

type

09/05/2007 - 09/05/2007

FIELD DATA

SuvSupNFPMPID

sam

ple

ID



Logged:Checked:


Aqua Drilling


MOISTURE CONDITION

visu

alra

nkin

g

2

KKGM

COMMENTS

field

test

s


SOILCONDITION

dry

dens

ity(t/

m )


of

mN mE

Grassed

11

12

13

14

15

16

17

18

19

20

dept

h (m

)

DENSITY (N-value)

grap

hic

log

(very loose)(loose)(medium dense)(dense)(very dense)(compact)A

BCD

moi

stur

eco

nditi

on

= Water level (during drilling)= Water level (static)GROUNDWATER SYMBOLS

SK

M E

NV

1 V

W03

861_

BO

RE

LOG

S.G

PJ

SK

M_E

NV

L1.G

DT

5/2

8/07


VISUAL RANKING FIELD DATA SYMBOLS

3Client:Start - Finish Date:Bore dia:

FIELD DATA ABBREVIATIONSVLLMDDVDCO

Sheet

= Shear vane test

= Outflow / Inflow

ODOUR RANKING



sam

ple

ID

moi

stur

e co

nten

t(%

)

09/05/2007 - 09/05/2007

FIELD DATA

VSSFStVStH

visu

alra

nkin

g


sam

ple

type


Aqua Drilling

SuvSupNFPMPID

PID

(ppm

)

SK

M E

NV

1 V

W03

861_

BO

RE

LOG

S.G

PJ

SK

M_E

NV

L1.G

DT

5/2

8/07

< 12 kPa12 - 2525 - 5050 - 100100 - 200> 200 kPa

cons

iste

ncy/

dens

ity


grou

nd w

ater

LAB DATA



BOREHOLE No. CW3

0123

= Disturbed Sample

50mm


SAND: Coarse sands, minor grey and orange clayinterbedded between the coarse sands.

Lays of organic dark black peat present. (continued)


Silty CLAY: Grey in colour. Likely to be weatheredsiltstone.

As above. Minor sands present.

CLAY: Grey mottled red clays. No sand present.

CLAY mixed with sandstone: Yellow/brown clays withsandstone fragments.

SANDSTONE: Light grey sandstone and gravels andcoarse sands. Colour variations from light grey, darkgrey, orange, brown and white.

Clayey SAND: Coarse grained sands mixed withorange and grey clays.

SAND: Coarse sands no clays present.

M

CONSISTENCY (Su)

Logged:Checked:



odou

rra

nkin

g

M

MOISTURE CONDITION

M

M

M

M

M



COMMENTS

= Shear vane test

SOILCONDITION


field

test

s

KKGM

moi

stur

eco

nditi

on


field

test

s

= Bulk Sample

mN mE

Grassed

dry

dens

ity(t/

m )

ofSheet

DENSITY (N-value)

grap

hic

log


3

dept

h (m

)

21

22

23

24

25

26

27

28

29

30

VISUAL RANKINGVLLMDDVDCO

FIELD DATA SYMBOLS

3


ABCD

SOIL DESCRIPTION

4

<1010 - 2020 - 3030 - 50>50>50/150mm


ODOUR RANKING


FIELD DATA ABBREVIATIONS= Uncorrected vane shear (kPa)= Pocket penetrometer (kPa)= SPT blows per 300mm= Field permeability= Photoionisation detector reading (ppm, V/V)


CONSISTENCY (Su)

= Disturbed Sample

0123

BOREHOLE No. CW3



PID

(ppm

)LAB DATA



cons

iste

ncy/

dens

ity

< 12 kPa12 - 2525 - 5050 - 100100 - 200> 200 kPa

grou

nd w

ater

VSSFStVStH

= Bulk Sample

<1010 - 2020 - 3030 - 50>50>50/150mm

4

SOIL DESCRIPTION

field

test

s

Silty CLAY: Grey in colour. Likely to be weatheredsiltstone. (continued)

Borehole terminated at 31.5 mbgl.



odou

rra

nkin

g



Logged:Checked:50mm

MOISTURE CONDITION



sam

ple



visu

alra

nkin

g

sam

ple

ID

SuvSupNFPMPID

FIELD DATA

09/05/2007 - 09/05/2007m

oist

ure

cont

ent

(%)3

Aqua Drilling

4


COMMENTS

field

test

s


SOILCONDITION

dry

dens

ity(t/

m )

moi

stur

eco

nditi

on

dept

h (m

)



grap

hic

log

DENSITY (N-value)

of

31

32

33

34

35

36

37

38

39

40

Grassed

mN mE



ABCD




= Outflow / Inflow

KKGM

VLLMDDVDCO

SheetS

KM

EN

V 1

VW

0386

1_B

OR

ELO

GS

.GP

J S

KM

_EN

VL1

.GD

T 5

/28/

07

ODOUR RANKING


= Shear vane test

SuvSupNFPMPID

grou

nd w

ater

moi

stur

e co

nten

t(%

)


FIELD DATA

0123

sam

ple

ID

visu

alra

nkin

g


sam

ple

type

<1010 - 2020 - 3030 - 50>50>50/150mm

09/05/2007 - 09/05/2007Project:Location:Job No:

= Bulk Sample

SK

M E

NV

1 V

W03

861_

BO

RE

LOG

S.G

PJ

SK

M_E

NV

L1.G

DT

5/2

8/07

CONSISTENCY (Su)

field

test

s

< 12 kPa12 - 2525 - 5050 - 100100 - 200> 200 kPa


= Disturbed Sample

LAB DATAP

ID(p

pm)



BOREHOLE No. CW4

Aqua Drilling

cons

iste

ncy/

dens

ity

SURFACE: TOPSOIL: Topsoil including organicmatter and tree roots.

Sandy CLAY: Orange clays mixed with sand (50% ofeach).

Sandy CLAY: Orange clays mixed with coarsegrained sands. Slightly mottled grey.

BASALT: Basalt chips present in brown clays.

CLAY: Black/brown clays with some rock fragments.

Highly weathered Basalt rock fragments upto 7cm insize mixed with orange brown clays.




MOISTURE CONDITION

50mmLogged:Checked:


odou

rra

nkin

g

M

M

M

M

D

M

VSSFStVStH


COMMENTS

dry

dens

ity(t/

m )

SOILCONDITION


Sheet

field

test

s

KKGM

moi

stur

eco

nditi

on

mN mE

Grassed

of

DENSITY (N-value)

grap

hic

log


1

dept

h (m

)

VLLMDDVDCO

1

2

3

4

5

6

7

8

9

10

= Shear vane test

ABCD


FIELD DATA SYMBOLS

3




SOIL DESCRIPTION

3


ODOUR RANKING

VISUAL RANKING

GROUNDWATER SYMBOLS


= Outflow / Inflow= Water level (during drilling)= Water level (static)

MOISTURE CONDITION


sam

ple

ID

visu

alra

nkin

g


sam

ple

type


SuvSupNFPMPID


FIELD DATA

50mmLogged:Checked:



odou

rra

nkin



Aqua DrillingProject:Location:Job No:

LAB DATA

SK

M E

NV

1 V

W03

861_

BO

RE

LOG

S.G

PJ

SK

M_E

NV

L1.G

DT

5/2

8/07



BOREHOLE No. CW4

= Disturbed Sample

M

grou

nd w

ater

moi

stur

e co

nten

t(%

)

09/05/2007 - 09/05/2007

0123

CLAY: Dark grey clays with minor sands.

Sandy SILT: Grey sandy silt mixed with fine tomedium sands.

CLAY: Dark grey clays with minor sands, silty orangeclay and light grey sandy clay.

As above with slightly darker grey clays.

SAND: Coarse sands with minimal silts and clays.

Sandy SILT: Light grey sandy silts with some quartssands.

Silty CLAY: Orange mottled dark grey clays withsome sands.

M

As above except some slightly darker grey clays.

PID

(ppm

)

M

M

M

M

M

M

SANDS: Coarse sands.

Sandy CLAY: Coarse dark grey sands.

Peat Layer encountered.

Weathered grey siltstone encounted.

M

M


SOILCONDITION


field

test

s

COMMENTS

moi

stur

eco

nditi

on

City of Casey

cons

iste

ncy/

dens

ity

= Shear vane test

KKGM

DENSITY (N-value)

mN mE

Grassed

11

12

13

14

15

16

17

18

19

20

dry

dens

ity(t/

m )

grap

hic

log


2

dept

h (m

)

Sheet of


ODOUR RANKING

VLLMDDVDCO

SOIL DESCRIPTION

3

3

<1010 - 2020 - 3030 - 50>50>50/150mm

= Bulk Sample

VSSFStVStH

CONSISTENCY (Su)

field

test

s

< 12 kPa12 - 2525 - 5050 - 100100 - 200> 200 kPa



FIELD DATA SYMBOLS




ABCD

VISUAL RANKING


SuvSupNFPMPID

21

22

23

24

25

26

27

28

29

30

Grassed

mN mE

SK

M E

NV

1 V

W03

861_

BO

RE

LOG

S.G

PJ

SK

M_E

NV

L1.G

DT

5/2

8/07

Borehole Terminated at 20.0 mbgl.



odou

rra

nkin

g

DENSITY (N-value)

Logged:Checked:50mm

MOISTURE CONDITION


Aqua Drilling


sam

ple



visu

alra

nkin

g

sam

ple

ID


= Shear vane test

Sheet

VLLMDDVDCO


moi

stur

eco

nditi

on

KKGM

COMMENTS

field

test

s

of

FIELD DATA


SOILCONDITION

dry

dens

ity(t/

m )

dept

h (m

)

3


grap

hic

log

GROUNDWATER SYMBOLS


3


ABCD


3

= Water level (static)= Water level (during drilling)

= Outflow / Inflow




PID

(ppm

)

09/05/2007 - 09/05/2007m

oist

ure

cont

ent

(%)

grou

nd w

ater

= Disturbed Sample

0123

BOREHOLE No. CW4


SOIL DESCRIPTION


ODOUR RANKING

LAB DATA



cons

iste

ncy/

dens

ity

< 12 kPa12 - 2525 - 5050 - 100100 - 200> 200 kPa

field

test

s


= Bulk Sample

<1010 - 2020 - 3030 - 50>50>50/150mm

City of Casey



Appendix B Analysis of Aquifer ‘Slug Tests’

0. 0.6 1.2 1.8 2.4 3.0.01

0.1

1.

10.

Time (min)

Dis

pla

cem

ent (m

)

CW1_FALLING

Data Set: I:\WCMS\Projects\WC03861\Technical\Slug Tests\CW1_Falling.aqtDate: 07/03/07 Time: 09:34:09

PROJECT INFORMATION

Company: SKMClient: City of CaseyProject: VW03861Location: Cranbourne WestTest Well: NBKKTest Date: 22/05/07

AQUIFER DATA

Saturated Thickness: 16.76 m Anisotropy Ratio (Kz/Kr): 1.

WELL DATA (CW1)

Initial Displacement: 1.313 m Static Water Column Height: 6. mTotal Well Penetration Depth: 6. m Screen Length: 6. mCasing Radius: 0.05 m Well Radius: 0.15 m

SOLUTION

Aquifer Model: Unconfined Solution Method: Bouwer-Rice

K = 2.462 m/day y0 = 2.982 m

0. 0.4 0.8 1.2 1.6 2.0.01

0.1

1.

10.

Time (min)

Dis

pla

cem

ent (m

)

CW1_FALLING_2

Data Set: I:\WCMS\Projects\WC03861\Technical\Slug Tests\CW1_Falling_2.aqtDate: 07/03/07 Time: 09:35:16

PROJECT INFORMATION

Company: SKMClient: City of CaseyProject: VW03861Location: Cranbourne WestTest Well: NBKKTest Date: 22/05/07

AQUIFER DATA


WELL DATA (CW1_2)


SOLUTION


K = 2.399 m/day y0 = 1.232 m

0. 0.1 0.2 0.3 0.4 0.50.01

0.1

1.

Time (min)

Dis

pla

cem

ent (m

)

CW1_RISING

Data Set: I:\WCMS\Projects\WC03861\Technical\Slug Tests\CW1_Rising.aqtDate: 07/03/07 Time: 09:36:15

PROJECT INFORMATION

Company: SKMClient: City of CaseyProject: VW03861Location: Cranbourne WestTest Well: CW1Test Date: 22/05/07

AQUIFER DATA


WELL DATA (CW1)


SOLUTION


K = 5.259 m/day y0 = 0.6063 m

0. 4. 8. 12. 16. 20.0.001

0.01

0.1

1.

10.

Time (min)

Dis

pla

cem

ent (m

)

GW4_FALLING

Data Set: I:\WCMS\Projects\WC03861\Technical\Slug Tests\GW4_Falling.aqtDate: 07/03/07 Time: 09:30:17

PROJECT INFORMATION

Company: SKMClient: City of CaseyProject: VW03861Location: Cranbourne WestTest Well: NB2Test Date: 22/05/07

AQUIFER DATA


WELL DATA (GW4)


SOLUTION


K = 1.343 m/day y0 = 0.6645 m

0. 0.8 1.6 2.4 3.2 4.0.001

0.01

0.1

1.

Time (min)

Dis

pla

cem

ent (m

)

GW4_RISING

Data Set: I:\WCMS\Projects\WC03861\Technical\Slug Tests\GW4_Rising.aqtDate: 07/03/07 Time: 09:32:52

PROJECT INFORMATION

Company: SKMClient: City of CaseyProject: VW03861Location: Cranbourne WestTest Well: NB2Test Date: 22/05/07

AQUIFER DATA


WELL DATA (GW4)


SOLUTION


K = 1.851 m/day y0 = 0.4573 m

0. 3. 6. 9. 12. 15.0.01

0.1

1.

10.

Time (min)

Dis

pla

cem

ent (m

)

GW2_FALLING

Data Set: I:\WCMS\Projects\WC03861\Technical\Slug Tests\GW2_Falling.aqtDate: 06/22/07 Time: 16:06:48

PROJECT INFORMATION

Company: SKMClient: City of CaseyProject: WV03861Test Location: Cranbourne WestTest Well: GW2Test Date: 22/05/2007

AQUIFER DATA

Saturated Thickness: 4. m Anisotropy Ratio (Kz/Kr): 1.

WELL DATA (GW2)

Initial Displacement: 0.951 m Casing Radius: 0.05 mWellbore Radius: 0.1 m Well Skin Radius: 0.1 mScreen Length: 6. m Total Well Penetration Depth: 4. mGravel Pack Porosity: 0.1

SOLUTION


K = 0.2927 m/day y0 = 0.9418 m

0. 4. 8. 12. 16. 20.0.001

0.01

0.1

1.

10.

Time (min)

Dis

pla

cem

ent (m

)

GW2_RISING

Data Set: I:\WCMS\Projects\WC03861\Technical\Slug Tests\GW2_rising.aqtDate: 06/22/07 Time: 16:09:56

PROJECT INFORMATION

Company: SKMClient: City of CaseyProject: WV03861Test Location: Cranbourne WestTest Well: GW2Test Date: 22/05/2007

AQUIFER DATA

Saturated Thickness: 4. m Anisotropy Ratio (Kz/Kr): 1.

WELL DATA (GW2)


SOLUTION


K = 0.704 m/day y0 = 1.511 m

0. 1.6 3.2 4.8 6.4 8.0.01

0.1

1.

Time (min)

Dis

pla

cem

ent (m

)

CW4_FALLING

Data Set: I:\WCMS\Projects\WC03861\Technical\Slug Tests\CW4_falling.aqtDate: 06/22/07 Time: 16:14:08

PROJECT INFORMATION

Company: SKMClient: City of CaseyProject: VW03861Test Location: Cranbourne WestTest Well: MONTest Date: 22/05/07

AQUIFER DATA


WELL DATA (CW5)


SOLUTION


K = 3.046 m/day y0 = 0.2039 m

0. 0.1 0.2 0.3 0.4 0.50.01

0.1

1.

Time (min)

Dis

pla

cem

ent (m

)

CW4_RISING

Data Set: I:\WCMS\Projects\WC03861\Technical\Slug Tests\CW4_rising.aqtDate: 06/22/07 Time: 16:22:27

PROJECT INFORMATION

Company: SKMClient: City of CaseyProject: VW03861Test Location: Cranbourne WestTest Well: CW4Test Date: 22/05/07

AQUIFER DATA


WELL DATA (CW4)


SOLUTION


K = 19.09 m/day y0 = 0.1995 m



Appendix C Groundwater Beneficial Use Categories

Segments (mg/L TDS)

A1

0 - 500

A2

501 -

1,000

B

1,001 -

3,500

C

3,501 -

13,000

D

greater

than

13,000

Beneficial Uses

1. Maintenance of Ecosystems

2. Potable Water Supply:

desirable *

acceptable *

3. Potable Mineral Water

4. Agriculture, Parks and Gardens

5. Stock Watering

6. Industrial Water Use

7. Primary Contact Recreation

(eg. bathing, swimming)

8. Buildings and Structures

(From Victorian EPA - State Environment Protection Policy Groundwaters of Victoria, 1997)





Appendix D Submission to Cranbourne West Draft Precinct Plan

Groundwater Conditions affecting the Cranbourne West Draft Precinct Plan 25 June 2007


I:\WCMS\Projects\WC03861\Deliverables\Groundwater_Precinct_Plan.doc PAGE 1

Date: 25th June, 2007 Project: Integrating Groundwater into the Urban Water Cycle: Cranbourne West,

Smart Water Fund project File Note: Groundwater conditions that may affect the Cranbourne West Draft

Precinct Plan

Sinclair Knight Merz is currently completing an investigation into the groundwater conditions at the southern end of the Cranbourne West Growth Area. The City of Casey (Wendy van Dok) has requested that we produce this short note summarising findings prior to completing our project, so that these findings can be considered in the further development of the Cranbourne West Draft Precinct Plan.

In summary our preliminary findings are: A significant area with watertables at depths of 1.5 m or less is expected in the south west

of the Cranbourne West Growth Area; The shallow watertable appears to be maintained by the local hydrogeological conditions

and the convergence of local groundwater flow; A depth to watertable of 1.5 m or less was categorised as “not recommended for urban

development” by SKM (2005) Our findings are consistent with those of SKM (2005), however rather than precluding

urban development, it may be possible to adopt a land use that is suited to the groundwater conditions or consider options for extraction and use of a volume of groundwater to effectively lower the watertable to manageable levels.

Further detail is provided below. Groundwater observation bores have been constructed at four locations within the south western corner of the Cranbourne West Growth Area (Figure 1).




Figure 1. Locations of groundwater observation bores constructed at the southern end of the Cranbourne West Growth Area. Groundwater bores are shown as red dots with labels (bores CW1, CW2, CW3 and CW4 have been constructed in this project, bores GW2 and GW4 were already present at the start of the project). The boundary of the growth area is shown as a green line.

345000 345500

5779200

5779400

5779600

5779800

5780000

5780200

5780400

5780600

5780800

5781000

CW1

CW2

CW3

CW4

GW2

GW4

Hall Rd

Wes

tern

port

Hig

hway

The construction of the groundwater observation bores provided a good opportunity to investigate the nature of the soil and geology profiles underlying the site. A sandy profile was recorded to depths greater than 20 m during the construction of groundwater bores CW1 and CW3. Bore CW2 lies in an area with a low permeability basalt layer in the near surface and bore CW4 was found to be on the boundary between the basalt and the sand areas.

The groundwater levels recorded in the bores in May 2007 are shown in Figure 2. Water levels in bores CW1, CW3 and CW4 represent the groundwater potential in sand layers that are partially confined by overlying soil/geological layers of lower permeability. These levels suggest significant areas within Figure 2 may have an underlying watertable at a depth of 1.5 m or shallower. An earlier report investigating constraints of shallow watertables to urban development (SKM, 2005) indicated that a depth to watertable of 1.5 m or shallower would be categorised as ‘Not Recommended for Urban Development’.




Figure 2. Cranbourne West: water levels observed in groundwater observation bores May 2007 (metres below natural surface). Note that some groundwater bores are screened in semi-confined sand layers.

345000 345500

5779200

5779400

5779600

5779800

5780000

5780200

5780400

5780600

5780800

5781000

0.18

4.94

0.86

4.26

4.97

1.08

Hall Rd

Wes

tern

port

Hig

hway

Our developing conceptual model of the groundwater system in this area is as follows; Figure 3 provides some contextual information. Groundwater flow appears to converge on the south western corner of the Cranbourne West growth area from a large contributing area south and up-gradient. This groundwater flow meets an ‘Older Volcanics’ basalt layer of low permeability (Figure 3) and is largely diverted to the west. Near-surface groundwater levels are observed where the groundwater flow is impeded by the presence of the basalt.




Figure 3. Land surface elevation (mAHD) at the southern end of the Cranbourne West Growth Area. Roads are shown as black lines, the boundary of the development as a green line and the area with a purple boundary is mapped as a surface layer of basalt (Geological Survey of Victoria, 1971). Our preliminary interpretation of groundwater flow direction is given by the blue lines.

Shallow watertables have been observed in groundwater bore GW4 since it was first constructed in September 2005 (Lane Consulting, 2005). These shallow watertables that have persisted through a long period of less-than-average rainfall support the conceptual model of groundwater flow. Further details of groundwater levels and bore construction will be provided in the final project report.

The constraints posed by a shallow watertable to urban development have been investigated by SKM (2005). These constraints are summarised in two tables that are reproduced below in Table 1 or Table 2. An area with a depth to watertable of 1.5 m or less for 90 % of the climate record falls into Category 5: ‘Not recommended for urban development’. Additional areas in Categories 3 and 4 are also expected (these categories are ‘Highly Constrained’ & ‘Severely Constrained’ respectively). The area for which these conditions are expected to occur will be estimated in the upcoming report of the groundwater investigation, however please note that the constraints are considered to be highly significant. It is recommended that land uses that are not precluded by (or strongly affected) by shallow watertables be seriously considered in the development of the Precinct Plan (e.g. suitable native vegetation).

Hall Rd.

Wester

n Port

High

way

5101520253035404550556065707580859095100

North

South




The tables below have been re-produced from the report ‘Watertable constraints to Urban Development’ SKM(2005). Table 1 and Table 2 below appeared as Table 4 and Table 12 in SKM(2005).

Table 1. Constraint categories defined for the Casey-Cardinia growth area.

Category Constraint category (and summary)

Expanded definition Impacts for Developer

Impacts for Local Authority

Impacts for Utilities

Companies

Impacts for Property owner

1 No significant constraints. Costs for development and management to attain amenity and function of a non-shallow watertable affected area are comparable.

Shallow watertable are not likely to occur with the exception of small, localised areas associated with local soils types and geology. Construction and management of urban infrastructure not dictated by shallow watertables.

None None None None

2 Constrained – some design and construction measures may be necessary based on existing building and site development standards. Residential housing and associated gardens will require some additional protection measures. Principal costs to maintain function and amenity are up front. Ongoing management and maintenance should not differ from non-shallow watertable affected areas.

Shallow watertables may occur in the lifespan of the development. Built structures and services should be designed with materials that are resistant to period of emersion in groundwater for varying lengths of time at site specific salinities. Vegetation types should be selected with tolerance to wet soil conditions, and specific to the salinity of the groundwater that is likely to be encountered. The management options applied are considered to be low maintenance in the long term and will not require specific management plans or operation and maintenance costs. The focus is on materials and plant species designed to cope with conditions.





3 Highly Constrained – urban development will require significant additional cost in the design and construction phase, as well as specialised management approaches to maintain function and amenity. Commercial developments will need to consider

Persistence or salinity of shallow watertables will require engineering to resist long periods or aggressive groundwater conditions. Preference is on the use of construction materials and approaches to resist the watertable conditions, although additional engineered measures are likely to be required. In addition to construction material and


Ongoing maintenance and operation of engineered systems. If not engineered, infrastructure

Capital cost of construction Ongoing maintenance and operation of engineered systems.

Specific management of garden areas and species to be grown. If not engineered, infrastructure could be expected to have




engineering of structures and selective use of gardens, but are generally less constrained than residential.

techniques and species selection, active engineering options that will require operation and maintenance such as drainage systems, raising of garden beds, specialist irrigation systems, and groundwater pumping. Substantial additional costs required at construction with ongoing maintenance and operation

could be expected to have a reduced lifespan of up to 20%.

If not engineered, infrastructure could be expected to have a reduced lifespan of up to 20%.

a reduced lifespan of up to 20%. Possible increased maintenance costs of built structures.

4 Severely constrained – Design, construction and operation of built structures, infrastructure, domestic gardens and open space will require specialised engineering of materials, construction approaches and the likely incorporation of active engineering options to manage persistent shallow watertables. To maintain function and amenity, significant additional operational effort and cost will be incurred. Residential development severely constrained. As function and amenity requirements of commercial areas are lower, these areas are considered highly constrained.

Persistent and aggressive shallow groundwater conditions requiring intensive active engineering systems on top of material and species selection criteria. Drainage systems and groundwater pumping approaches are required to be maintained and operated for the protection of built structures and infrastructure for the majority of the time. Garden areas require specific management through the use of raised and tanked garden beds and irrigation and drainage systems.



Capital cost of construction Ongoing maintenance and operation of engineered systems. If not engineered, infrastructure could be expected to have a reduced lifespan of up to 50%.

Specific management of garden areas and species to be grown. If not engineered, infrastructure could be expected to have a reduced lifespan of up to 50%. Possible increased maintenance costs of built structures.

5 Not recommended for urban development. Active engineering would be required continuously to manage watertable levels to provide function, although amenity is still anticipated to be significantly impact.

Effectively continuous persistence of shallow watertables. Costs to manage are at all stages of the project, and are now such that viability even in construction phase may be compromised.


Ongoing maintenance and operation of engineered systems. If not engineered, infrastructure could be expected to have a reduced lifespan in excess of 50%.

Capital cost of construction Ongoing maintenance and operation of engineered systems. If not engineered, infrastructure could be expected to have a reduced lifespan in excess of 50%.

Specific management of garden areas and species to be grown. If not engineered, infrastructure could be expected to have a reduced lifespan in excess of 50%. Possible increased maintenance costs of built structures.




Table 2 Summary of definitions of constraint as applied to different land uses in an urban setting

Risk Category



1 No significant constraints on Urban Development

Shallow Watertables not likely to impact land use

2 Constrained Impacts at construction phase. Additional cost in longer term management expected to be minimal.



Management of impacts based around selection of plants with slightly higher salt tolerance. Once selected and planted, no additional specific management required.

3 Highly Constrained Substantial engineering required in construction phase, with some additional operation and maintenance cost throughout lifespan..



Selection of groundcover species to be resistant to the local groundwater now required. Use of fill or drainage in open space and domestic gardens more likely. Raising of flowerbeds recommended to protect low salt tolerant species over the lifespan of the development. Specialised irrigation management likely in years when watertable is shallow.

4 Severely Constrained Substantial cost in the construction phase and in ongoing operation and maintenance of management systems required to provide function.

Buildings, foundations, roads and infrastructure require use of materials and design measures to mitigate impacts of shallow watertables and associated salinity. Protection of built structures by use of fill (up to 1.0m) and likely to include perimeter and sub-surface drainage to protect specific assets. Sub-surface structures require tanking or drainage to protect. Roads and service infrastructure likely to require specific drainage (either deep surface drains, sub-surface drains or groundwater pumping) to maintain function. Significant additional effort and cost required to operate and maintain

Buildings, foundations, roads and infrastructure require use of materials and design measures to mitigate impacts of shallow watertables and associated salinity. Protection of built structures by use of fill (up to 1.0m) and likely to include perimeter and sub-surface drainage to protect specific assets. Sub-surface structures require tanking or drainage to protect. Roads and service infrastructure likely to require specific drainage (either deep surface drains, sub-surface drains or groundwater pumping) to maintain function. Significant additional effort and cost required

Selection of groundcover species to be resistant to the local groundwater now required. Use of fill or drainage in open space and domestic gardens required. Raising or tanking of flowerbeds and stands for shrubs and trees now required. Use of sub-surface drainage under any areas where groundcover establishment is important. Ongoing selection of salt tolerant species, and increased management of parks, open space and domestic gardens required. Irrigation scheduling now critical. Unlikely to be suitable for sporting based recreation reserves.




Risk Category



drainage and other specific engineering management approaches.

to operate and maintain drainage and other specific engineering management approaches.

5 Not Recommended for Urban Development # Costs and impacts unacceptable for use of land as an urban development.



Limited long term prospect for successful plantings, high risk to investment in landscaping asset and high likelihood of significant maintenance costs and/or extensive engineering works. All flowerbeds, tree and shrub plantings in raised or tanked beds. Groundcover plants only likely to be those tolerant to waterlogged and/or high salinity watertable. Management of open space and gardens highly intensive. Unsuitable for sporting based recreation reserves.

# Site specific groundwater investigations required accompanied with an engineering response report




References

Geological Survey of Victoria, 1971. Queenscliff 1:250,000 Geological Map.

Lane Consulting, 2005. Hydrogeological assessment report, 570 Hall Road, Cranbourne West.

Sinclair Knight Merz (SKM), 2005. Shallow watertable constraints on urban development. Melbourne 2030, Department of Sustainability and Environment, Victoria.

Carl Daamen SKM Phone: +61 3 9248 3439 Fax: +61 3 9248 3364 E-mail: [email protected]

Documents

Integrating Groundwater into the Urban Water Cycle · Urban Design: Draft Issues report (Ecological Engineering, 2006). 2.5 Further Consultation with Experts Discussions were held