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.
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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.
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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)
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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.
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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
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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.
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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.
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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
Apco Service Station, Cnr Hall Road and Westernport Hwy, Cranbourne West 4.62 30.7 not taken
GW3
Apco Service Station, Cnr Hall Road and Westernport Hwy, Cranbourne West 3.79 30.71 not taken
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
5780600
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).
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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.
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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.
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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.
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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
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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.
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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.
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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
5782000
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.
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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
-20
0
20
40
60
80
100
01000200030004000500060007000Distance
mAH
D
SEWL1aSEWL1
Basement
Clay
Cranbourne West
Bore 76496
Bore 76321
Geological Strata discontinuous
West of Selwyn Fault
Bore 76561
76496
76561
76321
76296
Dunes
-40
-20
0
20
40
60
80
100
01000200030004000500060007000Distance
mAH
D
SEWL1aSEWL1
Basement
Clay
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.
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0
10
20
30
40
50
60
70
80
90
Hei
ght a
bove
sea
leve
l (m
AH
D)
76297
133349
Basalt
Basement
Dunes
Sand/Peat
76512
Bore 76512
57483
Bore
57483Bore 133349
Bore 76297
0
10
20
30
40
50
60
70
80
90
Hei
ght a
bove
sea
leve
l (m
AH
D)
76297
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.
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-40
-20
0
20
40
60
80
-1000 0 1000 2000 3000 4000 5000 6000 7000Distance along transect (m) transect begins at Groundwater Bore 76454
Land
sur
face
ele
vatio
n (m
AH
D)
Cra
nbou
rne
Wes
t N
orth
ern
Boun
dar y
Cra
nbou
rne
Wes
t S
outh
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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.
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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
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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.
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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
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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.
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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.
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Figure 21. Reduced groundwater level (mAHD).
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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
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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
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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).
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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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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.
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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
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
Capital cost of construction
Ongoing maintenance
Capital cost of construction
Specific management of
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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.
Ongoing maintenance and operation of engineered systems. If not engineered, infrastructure could be expected to have a reduced lifespan of up to 50%.
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.
Capital cost of construction Operation over covenant period.
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%.
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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.
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.
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
Final Report: Integrating Groundwater into the Urban Water Cycle
SINCLAIR KNIGHT MERZ The SKM logo is a trade mark of Sinclair Knight Merz Pty Ltd. © Sinclair Knight Merz Pty Ltd, 2006
I:\VWES\Projects\VW04032\Deliverables\Casey_SWF_Final_Sept26.doc PAGE
51
Risk Category
Risk Definition Urban Residential Built Structures and Services
Commercial Built Structures and Services Open Space / Domestic Gardens
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.
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
Final Report: Integrating Groundwater into the Urban Water Cycle
SINCLAIR KNIGHT MERZ I:\VWES\Projects\VW04032\Deliverables\Casey_SWF_Final_Sept26.doc PAGE 52
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
Final Report: Integrating Groundwater into the Urban Water Cycle
SINCLAIR KNIGHT MERZ I:\VWES\Projects\VW04032\Deliverables\Casey_SWF_Final_Sept26.doc PAGE 53
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);
Final Report: Integrating Groundwater into the Urban Water Cycle
SINCLAIR KNIGHT MERZ I:\VWES\Projects\VW04032\Deliverables\Casey_SWF_Final_Sept26.doc PAGE 54
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)
Final Report: Integrating Groundwater into the Urban Water Cycle
SINCLAIR KNIGHT MERZ I:\VWES\Projects\VW04032\Deliverables\Casey_SWF_Final_Sept26.doc PAGE 55
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
Final Report: Integrating Groundwater into the Urban Water Cycle
SINCLAIR KNIGHT MERZ I:\VWES\Projects\VW04032\Deliverables\Casey_SWF_Final_Sept26.doc PAGE 56
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.
Final Report: Integrating Groundwater into the Urban Water Cycle
SINCLAIR KNIGHT MERZ I:\VWES\Projects\VW04032\Deliverables\Casey_SWF_Final_Sept26.doc PAGE 57
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.
Final Report: Integrating Groundwater into the Urban Water Cycle
SINCLAIR KNIGHT MERZ I:\VWES\Projects\VW04032\Deliverables\Casey_SWF_Final_Sept26.doc PAGE 58
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
D = Dry M = Moist W = Wet
Aqua Drilling and Grouting
= Undisturbed Tube Sample
MOISTURE CONDITION
50mmLogged:Checked:
field
test
s
soil type, unified classification, colour, structure,particle characteristics, minor components
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
= Pocket Penetrometer test
LAB DATAP
ID(p
pm)
Driller:Rig:Surface Conditions:
Cranbourne West DrillingCranbourne WestVW04032
0123
= Disturbed Sample
grou
nd w
ater
moi
stur
e co
nten
t(%
)
= SPT Spoon Sample (Pushed)
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
(very soft)(soft)(firm)(stiff)(very stiff)(hard)
Silty SAND: Orange, becoming finer (continued)
Sandy SILT: Orange brown, fine grain W
odou
rra
nkin
gdrilling method, wellconstruction, water
and additionalobservations
W
W
W
W
W
Silty SAND & Grey Clayey SAND: Mottled orangeand grey
W
cons
iste
ncy/
dens
ity
W
KKGM
SOILCONDITION
No visible evidence of contaminationSlight visible contaminationVisible contaminationSignificant visible contamination
COMMENTS
moi
stur
eco
nditi
on
Northings:Eastings:RL:
Project:Location:Job No:
= 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
(very loose)(loose)(medium dense)(dense)(very dense)(compact)
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
= Standard Penetration Test (SPT top = start of N blowcount)
Client:Start - Finish Date:Bore dia:
ABCD
= Water level (static)
= Outflow / Inflow
No Non-Natural odoursSlight Non-Natural odoursModerate Non-Natural odoursStrong Non-Natural odours
= Water level (during drilling)
FIELD DATA ABBREVIATIONS
GROUNDWATER SYMBOLS
BOREHOLE No. CW1
0123
= Disturbed Sample
sam
ple
ID
moi
stur
e co
nten
t(%
)
Driller:Rig:Surface Conditions:
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)
Cranbourne West DrillingCranbourne WestVW04032
field
test
s
City of Casey
cons
iste
ncy/
dens
ity
= Pocket Penetrometer test
Project:Location:Job No:
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:
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
W
50mm
W
(very soft)(soft)(firm)(stiff)(very stiff)(hard)
= SPT Spoon Sample (Pushed)
odou
rra
nkin
gdrilling method, wellconstruction, water
and additionalobservations
MOISTURE CONDITION
dry
dens
ity(t/
m )
SOILCONDITION
No visible evidence of contaminationSlight visible contaminationVisible contaminationSignificant visible contamination
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
(very loose)(loose)(medium dense)(dense)(very dense)(compact)
3
VLLMDDVDCO
21
22
23
24
25
26
27
28
29
30
3
GROUNDWATER SYMBOLS
Northings:Eastings:RL:
No Non-Natural odoursSlight Non-Natural odoursModerate Non-Natural odoursStrong Non-Natural odours
ABCD
VISUAL RANKING
= Water level (during drilling)
FIELD DATA SYMBOLS
= Water level (static)
Client:Start - Finish Date:Bore dia:
Sheet
= Shear vane testFIELD DATA ABBREVIATIONS
ODOUR RANKING
= Outflow / Inflow
= 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)
< 12 kPa12 - 2525 - 5050 - 100100 - 200> 200 kPa
grou
nd w
ater
= Disturbed Sample
0123
BOREHOLE No. CW1
Cranbourne West DrillingCranbourne WestVW04032
City of Casey Driller:Rig:Surface Conditions:
PID
(ppm
)LAB DATA
Project:Location:Job No:
cons
iste
ncy/
dens
ity
field
test
s
CONSISTENCY (Su)VSSFStVStH
= Bulk Sample
<1010 - 2020 - 3030 - 50>50>50/150mm
4
SOIL DESCRIPTION
= Pocket Penetrometer test
= Undisturbed Tube Sample
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
and additionalobservations
odou
rra
nkin
g
= SPT Spoon Sample (Pushed)
(very soft)(soft)(firm)(stiff)(very stiff)(hard)
Logged:Checked:
moi
stur
e co
nten
t(%
)
visu
alra
nkin
g
Client:Start - Finish Date:Bore dia:
07/05/07 - 07/05/07
FIELD DATA
SuvSupNFPMPID
50mm
sam
ple
ID
MOISTURE CONDITION
soil type, unified classification, colour, structure,particle characteristics, minor components
sam
ple
type
D = Dry M = Moist W = Wet
Aqua Drilling and Grouting
4
moi
stur
eco
nditi
on
COMMENTS
field
test
s
No visible evidence of contaminationSlight visible contaminationVisible contaminationSignificant visible contamination
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
(very loose)(loose)(medium dense)(dense)(very dense)(compact)
Northings:Eastings:RL:
3
FIELD DATA SYMBOLSVISUAL RANKING
ABCD
No Non-Natural odoursSlight Non-Natural odoursModerate Non-Natural odoursStrong Non-Natural odours
FIELD DATA ABBREVIATIONS
GROUNDWATER SYMBOLS= Water level (static)= Water level (during drilling)
= Outflow / Inflow
KKGM
VLLMDDVDCO
Sheet
= Shear vane test
ODOUR RANKING
= 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)
sam
ple
ID
MOISTURE CONDITION
08/05/2007 - 09/05/2007
FIELD DATA
grou
nd w
ater
visu
alra
nkin
g
soil type, unified classification, colour, structure,particle characteristics, minor components
sam
ple
type
D = Dry M = Moist W = Wet
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
= Pocket Penetrometer test
moi
stur
e co
nten
t(%
)
LAB DATA
50mm
Driller:Rig:Surface Conditions:
City of CaseyCranbourne West DrillingCranbourne WestVW04032
BOREHOLE No. CW2
0123
= Disturbed Sample
Project:Location:Job No:
= Undisturbed Tube 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:
(very soft)(soft)(firm)(stiff)(very stiff)(hard)
= SPT Spoon Sample (Pushed)
odou
rra
nkin
gdrilling method, wellconstruction, water
and additionalobservations
BASALT: Fine grey basalt chips.
W
CONSISTENCY (Su)
M
D
D
D
W
COMMENTS
= Shear vane test
SOILCONDITION
No visible evidence of contaminationSlight visible contaminationVisible contaminationSignificant visible contamination
field
test
s
KKGM
moi
stur
eco
nditi
on
Northings:Eastings:RL:
field
test
s
= Bulk Sample
5780595.43 mN345206.3 mE
Grassed
dry
dens
ity(t/
m )
ofSheet
DENSITY (N-value)
grap
hic
log
(very loose)(loose)(medium dense)(dense)(very dense)(compact)
1
dept
h (m
)
1
2
3
4
5
6
7
8
9
10
VISUAL RANKINGVLLMDDVDCO
FIELD DATA SYMBOLS
3
No Non-Natural odoursSlight Non-Natural odoursModerate Non-Natural odoursStrong Non-Natural odours
ABCD
SOIL DESCRIPTION
3
<1010 - 2020 - 3030 - 50>50>50/150mm
Client:Start - Finish Date:Bore dia:
ODOUR RANKING
= Standard Penetration Test (SPT top = start of N blowcount)
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
soil type, unified classification, colour, structure,particle characteristics, minor components
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
Project:Location:Job No:
PID
(ppm
)
Driller:Rig:Surface Conditions:
City of CaseyCranbourne West DrillingCranbourne WestVW04032
BOREHOLE No. CW2
0123
= Undisturbed Tube Sample
= Pocket Penetrometer test
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.
D = Dry M = Moist W = Wet
BASALT: Grey basalt chips (gravel size <1cm).
BASALT: Grey basalt chips with increasing claycontent.
W
MOISTURE CONDITION
50mmLogged:Checked:
(very soft)(soft)(firm)(stiff)(very stiff)(hard)
= SPT Spoon Sample (Pushed)
drilling method, wellconstruction, water
and additionalobservations
W
W
W
W
W
W
= Bulk Sample
odou
rra
nkin
g
COMMENTS
dry
dens
ity(t/
m )
SOILCONDITION
No visible evidence of contaminationSlight visible contaminationVisible contaminationSignificant visible contamination
<1010 - 2020 - 3030 - 50>50>50/150mm
field
test
s
KKGM
moi
stur
eco
nditi
on
Northings:Eastings:RL:
CONSISTENCY (Su)
5780595.43 mN345206.3 mE
Grassed
of
DENSITY (N-value)
grap
hic
log
(very loose)(loose)(medium dense)(dense)(very dense)(compact)
2
dept
h (m
)
Sheet
11
12
13
14
15
16
17
18
19
20
= Shear vane test
ABCD
VLLMDDVDCO
FIELD DATA SYMBOLS
3
FIELD DATA ABBREVIATIONS
Client:Start - Finish Date:Bore dia:
No Non-Natural odoursSlight Non-Natural odoursModerate Non-Natural odoursStrong Non-Natural odours
SOIL DESCRIPTION
3
ODOUR RANKING
VISUAL RANKING
= Standard Penetration Test (SPT top = start of N blowcount)
GROUNDWATER SYMBOLS
= 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)
= Disturbed Sample
0123
BOREHOLE No. CW2
Cranbourne West DrillingCranbourne WestVW04032
City of Casey Driller:Rig:Surface Conditions:
PID
(ppm
)LAB DATA
Project:Location:Job No:
= Pocket Penetrometer test
cons
iste
ncy/
dens
ity
field
test
sgr
ound
wat
er
CONSISTENCY (Su)VSSFStVStH
= Bulk Sample
<1010 - 2020 - 3030 - 50>50>50/150mm
3
SOIL DESCRIPTION
< 12 kPa12 - 2525 - 5050 - 100100 - 200> 200 kPa
D = Dry M = Moist W = Wet
CLAY: Brown clays intermingled with quartz gravels.
Borehole Terminated at 23.0 mbgl and wellconstructed.
W
drilling method, wellconstruction, water
and additionalobservations
odou
rra
nkin
g
= SPT Spoon Sample (Pushed)
(very soft)(soft)(firm)(stiff)(very stiff)(hard)
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
(%)
= Undisturbed Tube Sample
3
Client:Start - Finish Date:Bore dia:
COMMENTS
field
test
s
No visible evidence of contaminationSlight visible contaminationVisible contaminationSignificant visible contamination
SOILCONDITION
dry
dens
ity(t/
m )
moi
stur
eco
nditi
on
dept
h (m
)
Northings:Eastings:RL:
(very loose)(loose)(medium dense)(dense)(very dense)(compact)
grap
hic
log
DENSITY (N-value)
of
21
22
23
24
25
26
27
28
29
30
Grassed
5780595.43 mN345206.3 mE
= Uncorrected vane shear (kPa)= Pocket penetrometer (kPa)= SPT blows per 300mm= Field permeability= Photoionisation detector reading (ppm, V/V)
FIELD DATA SYMBOLSVISUAL RANKING
ABCD
No Non-Natural odoursSlight Non-Natural odoursModerate Non-Natural odoursStrong Non-Natural odours
FIELD DATA ABBREVIATIONS
GROUNDWATER SYMBOLS= Water level (static)= Water level (during drilling)
= 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
= Standard Penetration Test (SPT top = start of N blowcount)
= 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
D = Dry M = Moist W = Wet
Aqua Drilling
= Undisturbed Tube Sample
MOISTURE CONDITION
50mmLogged:Checked:
(very soft)(soft)(firm)(stiff)(very stiff)(hard)
soil type, unified classification, colour, structure,particle characteristics, minor components
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
Project:Location:Job No:
PID
(ppm
)
Driller:Rig:Surface Conditions:
Cranbourne West DrillingCranbourne WestVW04032
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
= Pocket Penetrometer test
drilling method, wellconstruction, water
and additionalobservations
M
M
M
M
M
Sandy CLAY: Yellow-grey clays.
M
= SPT Spoon Sample (Pushed)
D
M
KKGM
SOILCONDITION
No visible evidence of contaminationSlight visible contaminationVisible contaminationSignificant visible contamination
COMMENTS
moi
stur
eco
nditi
on
Northings:Eastings:RL:
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
(very loose)(loose)(medium dense)(dense)(very dense)(compact)
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
= Standard Penetration Test (SPT top = start of N blowcount)
Client:Start - Finish Date:Bore dia:
ABCD
= Water level (static)
= Outflow / Inflow
No Non-Natural odoursSlight Non-Natural odoursModerate Non-Natural odoursStrong Non-Natural odours
= Water level (during drilling)
FIELD DATA ABBREVIATIONS
GROUNDWATER SYMBOLS
cons
iste
ncy/
dens
ity
moi
stur
e co
nten
t(%
)
grou
nd w
ater
= Disturbed Sample
0123
BOREHOLE No. CW3
Cranbourne West DrillingCranbourne WestVW04032
City of Casey Driller:Rig:Surface Conditions:
PID
(ppm
)LAB DATA
= Bulk Sample
SOIL DESCRIPTION
4
Project:Location:Job No:
<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
drilling method, wellconstruction, water
and additionalobservations
odou
rra
nkin
g
= SPT Spoon Sample (Pushed)
sam
ple
type
09/05/2007 - 09/05/2007
FIELD DATA
SuvSupNFPMPID
sam
ple
ID
(very soft)(soft)(firm)(stiff)(very stiff)(hard)
soil type, unified classification, colour, structure,particle characteristics, minor components
Logged:Checked:
D = Dry M = Moist W = Wet
Aqua Drilling
= Undisturbed Tube Sample
MOISTURE CONDITION
visu
alra
nkin
g
2
KKGM
COMMENTS
field
test
s
No visible evidence of contaminationSlight visible contaminationVisible contaminationSignificant visible contamination
SOILCONDITION
dry
dens
ity(t/
m )
Northings:Eastings:RL:
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
No Non-Natural odoursSlight Non-Natural odoursModerate Non-Natural odoursStrong Non-Natural odours
VISUAL RANKING FIELD DATA SYMBOLS
3Client:Start - Finish Date:Bore dia:
FIELD DATA ABBREVIATIONSVLLMDDVDCO
Sheet
= Shear vane test
= Outflow / Inflow
ODOUR RANKING
= 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)
sam
ple
ID
moi
stur
e co
nten
t(%
)
09/05/2007 - 09/05/2007
FIELD DATA
VSSFStVStH
visu
alra
nkin
g
soil type, unified classification, colour, structure,particle characteristics, minor components
sam
ple
type
D = Dry M = Moist W = Wet
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
= Pocket Penetrometer test
grou
nd w
ater
LAB DATA
Driller:Rig:Surface Conditions:
City of CaseyCranbourne West DrillingCranbourne WestVW04032
BOREHOLE No. CW3
0123
= Disturbed Sample
50mm
Project:Location:Job No:
SAND: Coarse sands, minor grey and orange clayinterbedded between the coarse sands.
Lays of organic dark black peat present. (continued)
= Undisturbed Tube Sample
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:
(very soft)(soft)(firm)(stiff)(very stiff)(hard)
= SPT Spoon Sample (Pushed)
odou
rra
nkin
g
M
MOISTURE CONDITION
M
M
M
M
M
drilling method, wellconstruction, water
and additionalobservations
COMMENTS
= Shear vane test
SOILCONDITION
No visible evidence of contaminationSlight visible contaminationVisible contaminationSignificant visible contamination
field
test
s
KKGM
moi
stur
eco
nditi
on
Northings:Eastings:RL:
field
test
s
= Bulk Sample
mN mE
Grassed
dry
dens
ity(t/
m )
ofSheet
DENSITY (N-value)
grap
hic
log
(very loose)(loose)(medium dense)(dense)(very dense)(compact)
3
dept
h (m
)
21
22
23
24
25
26
27
28
29
30
VISUAL RANKINGVLLMDDVDCO
FIELD DATA SYMBOLS
3
No Non-Natural odoursSlight Non-Natural odoursModerate Non-Natural odoursStrong Non-Natural odours
ABCD
SOIL DESCRIPTION
4
<1010 - 2020 - 3030 - 50>50>50/150mm
Client:Start - Finish Date:Bore dia:
ODOUR RANKING
= Standard Penetration Test (SPT top = start of N blowcount)
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
CONSISTENCY (Su)
= Disturbed Sample
0123
BOREHOLE No. CW3
Cranbourne West DrillingCranbourne WestVW04032
City of Casey Driller:Rig:Surface Conditions:
PID
(ppm
)LAB DATA
Project:Location:Job No:
= Pocket Penetrometer test
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.
drilling method, wellconstruction, water
and additionalobservations
odou
rra
nkin
g
= SPT Spoon Sample (Pushed)
(very soft)(soft)(firm)(stiff)(very stiff)(hard)
Logged:Checked:50mm
MOISTURE CONDITION
= Undisturbed Tube Sample
D = Dry M = Moist W = Wet
sam
ple
type soil type, unified classification, colour, structure,
particle characteristics, minor components
visu
alra
nkin
g
sam
ple
ID
SuvSupNFPMPID
FIELD DATA
09/05/2007 - 09/05/2007m
oist
ure
cont
ent
(%)3
Aqua Drilling
4
Client:Start - Finish Date:Bore dia:
COMMENTS
field
test
s
No visible evidence of contaminationSlight visible contaminationVisible contaminationSignificant visible contamination
SOILCONDITION
dry
dens
ity(t/
m )
moi
stur
eco
nditi
on
dept
h (m
)
Northings:Eastings:RL:
(very loose)(loose)(medium dense)(dense)(very dense)(compact)
grap
hic
log
DENSITY (N-value)
of
31
32
33
34
35
36
37
38
39
40
Grassed
mN mE
= Uncorrected vane shear (kPa)= Pocket penetrometer (kPa)= SPT blows per 300mm= Field permeability= Photoionisation detector reading (ppm, V/V)
FIELD DATA SYMBOLSVISUAL RANKING
ABCD
No Non-Natural odoursSlight Non-Natural odoursModerate Non-Natural odoursStrong Non-Natural odours
FIELD DATA ABBREVIATIONS
GROUNDWATER SYMBOLS= Water level (static)= Water level (during drilling)
= 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
= Standard Penetration Test (SPT top = start of N blowcount)
= Shear vane test
SuvSupNFPMPID
grou
nd w
ater
moi
stur
e co
nten
t(%
)
D = Dry M = Moist W = Wet
FIELD DATA
0123
sam
ple
ID
visu
alra
nkin
g
soil type, unified classification, colour, structure,particle characteristics, minor components
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
= Pocket Penetrometer test
= Disturbed Sample
LAB DATAP
ID(p
pm)
Driller:Rig:Surface Conditions:
City of CaseyCranbourne West DrillingCranbourne WestVW04032
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.
drilling method, wellconstruction, water
and additionalobservations
= Undisturbed Tube Sample
MOISTURE CONDITION
50mmLogged:Checked:
(very soft)(soft)(firm)(stiff)(very stiff)(hard)
odou
rra
nkin
g
M
M
M
M
D
M
VSSFStVStH
= SPT Spoon Sample (Pushed)
COMMENTS
dry
dens
ity(t/
m )
SOILCONDITION
No visible evidence of contaminationSlight visible contaminationVisible contaminationSignificant visible contamination
Sheet
field
test
s
KKGM
moi
stur
eco
nditi
on
mN mE
Grassed
of
DENSITY (N-value)
grap
hic
log
(very loose)(loose)(medium dense)(dense)(very dense)(compact)
1
dept
h (m
)
VLLMDDVDCO
1
2
3
4
5
6
7
8
9
10
= Shear vane test
ABCD
Northings:Eastings:RL:
FIELD DATA SYMBOLS
3
FIELD DATA ABBREVIATIONS
Client:Start - Finish Date:Bore dia:
No Non-Natural odoursSlight Non-Natural odoursModerate Non-Natural odoursStrong Non-Natural odours
SOIL DESCRIPTION
3
= Standard Penetration Test (SPT top = start of N blowcount)
ODOUR RANKING
VISUAL RANKING
GROUNDWATER SYMBOLS
= 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)
MOISTURE CONDITION
= Pocket Penetrometer test
sam
ple
ID
visu
alra
nkin
g
soil type, unified classification, colour, structure,particle characteristics, minor components
sam
ple
type
D = Dry M = Moist W = Wet
SuvSupNFPMPID
= Undisturbed Tube Sample
FIELD DATA
50mmLogged:Checked:
(very soft)(soft)(firm)(stiff)(very stiff)(hard)
= SPT Spoon Sample (Pushed)
odou
rra
nkin
gdrilling method, wellconstruction, water
and additionalobservations
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
Driller:Rig:Surface Conditions:
Cranbourne West DrillingCranbourne WestVW04032
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
Northings:Eastings:RL:
SOILCONDITION
No visible evidence of contaminationSlight visible contaminationVisible contaminationSignificant visible contamination
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
(very loose)(loose)(medium dense)(dense)(very dense)(compact)
2
dept
h (m
)
Sheet of
Client:Start - Finish Date:Bore dia:
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
= Uncorrected vane shear (kPa)= Pocket penetrometer (kPa)= SPT blows per 300mm= Field permeability= Photoionisation detector reading (ppm, V/V)
= Standard Penetration Test (SPT top = start of N blowcount)
FIELD DATA SYMBOLS
= Outflow / Inflow= 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
(very soft)(soft)(firm)(stiff)(very stiff)(hard)
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.
drilling method, wellconstruction, water
and additionalobservations
odou
rra
nkin
g
DENSITY (N-value)
Logged:Checked:50mm
MOISTURE CONDITION
= Undisturbed Tube Sample
Aqua Drilling
D = Dry M = Moist W = Wet
sam
ple
type soil type, unified classification, colour, structure,
particle characteristics, minor components
visu
alra
nkin
g
sam
ple
ID
= SPT Spoon Sample (Pushed)
= Shear vane test
Sheet
VLLMDDVDCO
Northings:Eastings:RL:
moi
stur
eco
nditi
on
KKGM
COMMENTS
field
test
s
of
FIELD DATA
No visible evidence of contaminationSlight visible contaminationVisible contaminationSignificant visible contamination
SOILCONDITION
dry
dens
ity(t/
m )
dept
h (m
)
3
(very loose)(loose)(medium dense)(dense)(very dense)(compact)
grap
hic
log
GROUNDWATER SYMBOLS
Client:Start - Finish Date:Bore dia:
3
FIELD DATA SYMBOLSVISUAL RANKING
ABCD
FIELD DATA ABBREVIATIONS
3
= Water level (static)= Water level (during drilling)
= Outflow / Inflow
= Uncorrected vane shear (kPa)= Pocket penetrometer (kPa)= SPT blows per 300mm= Field permeability= Photoionisation detector reading (ppm, V/V)
= Standard Penetration Test (SPT top = start of N blowcount)
No Non-Natural odoursSlight Non-Natural odoursModerate Non-Natural odoursStrong Non-Natural odours
PID
(ppm
)
09/05/2007 - 09/05/2007m
oist
ure
cont
ent
(%)
grou
nd w
ater
= Disturbed Sample
0123
BOREHOLE No. CW4
Cranbourne West DrillingCranbourne WestVW04032
SOIL DESCRIPTION
Driller:Rig:Surface Conditions:
ODOUR RANKING
LAB DATA
Project:Location:Job No:
= Pocket Penetrometer test
cons
iste
ncy/
dens
ity
< 12 kPa12 - 2525 - 5050 - 100100 - 200> 200 kPa
field
test
s
CONSISTENCY (Su)VSSFStVStH
= Bulk Sample
<1010 - 2020 - 3030 - 50>50>50/150mm
City of Casey
Final Report: Integrating Groundwater into the Urban Water Cycle
SINCLAIR KNIGHT MERZ I:\VWES\Projects\VW04032\Deliverables\Casey_SWF_Final_Sept26.doc PAGE 59
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
Saturated Thickness: 16.98 m Anisotropy Ratio (Kz/Kr): 1.
WELL DATA (CW1_2)
Initial Displacement: 2.194 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 = 2.399 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
Saturated Thickness: 16.76 m Anisotropy Ratio (Kz/Kr): 1.
WELL DATA (CW1)
Initial Displacement: 0.549 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 = 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
Saturated Thickness: 4.98 m Anisotropy Ratio (Kz/Kr): 1.
WELL DATA (GW4)
Initial Displacement: 2.729 m Static Water Column Height: 4. mTotal Well Penetration Depth: 4. m Screen Length: 4. mCasing Radius: 0.05 m Well Radius: 0.15 m
SOLUTION
Aquifer Model: Unconfined Solution Method: Bouwer-Rice
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
Saturated Thickness: 4.98 m Anisotropy Ratio (Kz/Kr): 1.
WELL DATA (GW4)
Initial Displacement: 0.732 m Static Water Column Height: 4. mTotal Well Penetration Depth: 4. m Screen Length: 4. mCasing Radius: 0.05 m Well Radius: 0.15 m
SOLUTION
Aquifer Model: Unconfined Solution Method: Bouwer-Rice
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
Aquifer Model: Unconfined Solution Method: Bouwer-Rice
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)
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
Aquifer Model: Unconfined Solution Method: Bouwer-Rice
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
Saturated Thickness: 11.28 m Anisotropy Ratio (Kz/Kr): 1.
WELL DATA (CW5)
Initial Displacement: 0.25 m Casing Radius: 0.05 mWellbore Radius: 0.15 m Well Skin Radius: 0.15 mScreen Length: 2. m Total Well Penetration Depth: 2. mGravel Pack Porosity: 0.1
SOLUTION
Aquifer Model: Unconfined Solution Method: Bouwer-Rice
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
Saturated Thickness: 11.28 m Anisotropy Ratio (Kz/Kr): 1.
WELL DATA (CW4)
Initial Displacement: 0.188 m Casing Radius: 0.05 mWellbore Radius: 0.15 m Well Skin Radius: 0.15 mScreen Length: 2. m Total Well Penetration Depth: 2. mGravel Pack Porosity: 0.1
SOLUTION
Aquifer Model: Unconfined Solution Method: Bouwer-Rice
K = 19.09 m/day y0 = 0.1995 m
Final Report: Integrating Groundwater into the Urban Water Cycle
SINCLAIR KNIGHT MERZ I:\VWES\Projects\VW04032\Deliverables\Casey_SWF_Final_Sept26.doc PAGE 60
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)
Final Report: Integrating Groundwater into the Urban Water Cycle
SINCLAIR KNIGHT MERZ I:\VWES\Projects\VW04032\Deliverables\Casey_SWF_Final_Sept26.doc PAGE 61
Final Report: Integrating Groundwater into the Urban Water Cycle
SINCLAIR KNIGHT MERZ I:\VWES\Projects\VW04032\Deliverables\Casey_SWF_Final_Sept26.doc PAGE 62
Appendix D Submission to Cranbourne West Draft Precinct Plan
Groundwater Conditions affecting the Cranbourne West Draft Precinct Plan 25 June 2007
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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).
Groundwater Conditions affecting the Cranbourne West Draft Precinct Plan 25 June 2007
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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’.
Groundwater Conditions affecting the Cranbourne West Draft Precinct Plan 25 June 2007
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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.
Groundwater Conditions affecting the Cranbourne West Draft Precinct Plan 25 June 2007
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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
Groundwater Conditions affecting the Cranbourne West Draft Precinct Plan 25 June 2007
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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.
Capital cost of construction
Minimal additional cost
Capital cost of construction
Minimal additional cost
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
Capital cost of construction Operation over covenant period.
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
Groundwater Conditions affecting the Cranbourne West Draft Precinct Plan 25 June 2007
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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 Operation over covenant period.
Ongoing maintenance and operation of engineered systems. If not engineered, infrastructure could be expected to have a reduced lifespan of up to 50%.
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.
Capital cost of construction Operation over covenant period.
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.
Groundwater Conditions affecting the Cranbourne West Draft Precinct Plan 25 June 2007
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Table 2 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.
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.
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 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.
Groundwater Conditions affecting the Cranbourne West Draft Precinct Plan 25 June 2007
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Risk Category
Risk Definition Urban Residential Built Structures and Services
Commercial Built Structures and Services Open Space / Domestic Gardens
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.
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.
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
Groundwater Conditions affecting the Cranbourne West Draft Precinct Plan 25 June 2007
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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]