STATEMENT OF EXPERT EVIDENCE CITY OF … Corp... · Armstrong Creek East Precinct Structure Plan City of Greater Geelong PS Amendment C206 ii Neil M Craigie Pty Ltd TABLE OF CONTENTS

Neil M Craigie Pty Ltd ACN 074 582 282 ABN 29 074 582 282

Waterway Management Consultants

Director Neil McKinnon Craigie BE(Civil), MEngSci, MIEAust, CPEng Email: [email protected]

15 Mulawa Street Croydon, Vic. 3136, Australia Telephone & Fax: (03) 9725 1053

STATEMENT OF EXPERT EVIDENCE

CITY OF GREATER GEELONG PLANNING SCHEME AMENDMENT C206

ARMSTRONG CREEK EAST PSP

SURFACE WATER MANAGEMENT

For: Armstrong Creek Development Corporation Pty Ltd

29 January 2010

Armstrong Creek East Precinct Structure Plan City of Greater Geelong PS Amendment C206

ii Neil M Craigie Pty Ltd

TABLE OF CONTENTS

1. NAME AND ADDRESS 1

2. QUALIFICATIONS AND EXPERIENCE 1

3. INSTRUCTIONS 1

4. THE ACEP STORMWATER MANAGEMENT STRATEGY 2

4.1 My Review Role 2

4.2 Some Key Conclusions of the Review 2

5. THE SUBMISSIONS 4

6. INFORMATION USED AND RELIED UPON 5

7. RESPONSE TO ISSUES RAISED 6

7.1 Designing for the Habitat Requirements of the Growling Grass Frog 6

7.2 Impacts of Recycled Water Supply Provision 7

7.3 Shallow Saline Groundwater 10

7.4 Raised Groundwater Levels and Impacts on Ramsar Wetlands 12

7.5 Armstrong Creek Waterway Corridor Width 14

7.6 Increased Flooding in Groves Road Area 14

8. SUMMARY AND CONCLUSIONS 16

9. DECLARATION 20

10. ABBREVIATIONS AND DEFINITIONS 21

11. REFERENCES 21

APPENDIX A STATEMENT OF QUALIFICATIONS AND EXPERIENCE 22

APPENDIX B EXISTING GROUNDWATER INFORMATION 25


1 Neil M Craigie Pty Ltd

1. Name and Address Neil McKinnon Craigie, 15 Mulawa Street, Croydon North, VIC, 3136.

2. Qualifications and Experience B.E. (Civil), Monash University 1975 Grad. Course in Engg. Hydrology, UNSW 1976 M.Eng. Sci., Monash University 1981

After 14 years professional employment with the former Dandenong Valley Authority

I commenced private practice as a waterway management consultant in 1989 and have

worked continuously in this role since then.

I am a recognised expert in the field of surface water management, waterway

management, and stormwater quality and quantity control measures. I have advised on

such issues on numerous rural, semi-urban and urban developments throughout

Victoria.

A Statement of Qualifications and Experience is attached as Appendix A.

3. Instructions

This statement has been prepared on the instruction of Norton Rose Australia on

behalf of the Armstrong Creek Development Corporation Pty Ltd. I was instructed to:

▪ review the submissions made to Planning Panels Victoria for Amendment

C206 which related to the Armstrong Creek East Precinct (ACEP) Stormwater

Management Strategy;

▪ prepare an expert witness statement for the purposes of the Advisory

Committee hearing;

▪ give evidence at the Advisory Committee hearing.



4. The ACEP Stormwater Management Strategy

4.1 My Review Role

The Stormwater Management Strategy (SWMS) for the Armstrong Creek East

Precinct was prepared by Bonacci Water and finalised in October 2009. I was

engaged by the City of Greater Geelong (CoGG) to conduct a peer review.

It was not the role of that review to repeat the detailed hydrologic and hydraulic

modelling that had been carried out by Bonacci Water. The review process was aimed

at confirming strategy approach and methodology and checking that all significant

constraints and opportunities had been identified and appraised and overall land

budget requirements were broadly appropriate. The review report was dated 2 October

2009.

4.2 Some Key Conclusions of the Review

Strategy Approach and Methodology

• The general strategy approach taken by Bonacci Water was supported and met

all best practice expectations.

• Bonacci Water used contemporary best practice hydrologic and hydraulic

modelling approaches in preparing the SWMS.

• The review produced comparable land take estimates to those produced by

Bonacci Water.

• The need to retain future design flexibility in precinct and sub-precinct

development must be paramount.

Armstrong Creek between Horseshoe Bend Road and Barwon Heads Road

• As concluded by Bonacci Water, remodelling to create a 32 m top water width

at 100 year ARI flow is feasible in engineering terms whilst integrating the

required linear detention storage and water quality treatment assets.

• While the width of 32 m could be adopted as the limit of land theoretically

affected by flooding for the purposes of calculating net developable land area,



it would be preferable for a wider waterway zone to be created featuring more

diverse flora/fauna/geomorphologic/landscape/recreational values.

• A 70 m average corridor width could provide for all of these design objectives

to be satisfactorily achieved.

Armstrong Creek between Surf Coast Highway and Horseshoe Bend Road

• Effective retention of the existing floodplain was supported.

Downstream (East) of Barwon Heads Road

• Locating most of the proposed detention storages within the 100 year ARI

floodplain area of the Barwon River was strongly supported. There is no

reason why lands within the floodplain area should not be used for flow

mitigation and water quality treatment for lands in the ACEP.

• Subject to land ownership limits/agreements the stormwater assets could be

located further downslope in the Barwon River floodplain, even below the 10

year ARI flood extent, so as to improve drainage outfall grades for the

developable lands and enhance design flexibility.

Class A recycled supply and stormwater reuse

• Class A recycled water will be mandated in the ACEP according to advice by

Barwon Water. This supply presents issues of high nutrient loadings as well as

cost.

• Reuse of roofwater and stormwater is strongly supported to mitigate impacts of

urban development but these water sources effectively compete with the

recycled supply for many uses.

• Retaining the option to use “free” roofwater and stormwater should be

attractive to landowners and Council and should be encouraged in the PSP.



5. The Submissions

This statement responds to issues relating to the ACEP SWMS which have been

raised in four submissions to Amendment C206 as summarised in Table 1.

TABLE 1 Submissions Relating to the ACEP SWMS

Submittor Date Key Issues Raised by Submittors

Although the Growling Grass Frog has not been identified within

the precinct by targeted surveys, there is the potential for the

species to be present. It is important to integrate the habitat

requirements of this species into stormwater and waterway design,

especially along the Armstrong Creek corridor.

Department of

Sustainability and

Environment (DSE)

11/1/10

The PSP does not address issues arising from changes in

prevailing salinity. The introduction of unmetered third pipe water

supply across the Precinct introduces possible salinity change

implications including:

• Raised saline groundwater

• Impacts on retained biodiversity

• Soil structure changes

• Risks to underground infrastructure including pipes and

foundations

• Saline runoff changing salinity and other characteristics in

Lake Connewarre State Game Reserve.

Corangamite

Catchment

Management

Authority (CCMA)

11/1/10 Potential effect of salinity increase from re-use water (sewerage)

to groundwater and into adjoining Ramsar lakes and wetlands has

not been quantified.

70 m wide stream buffers should be reinstated along the course of

Armstrong Creek and any other relevant watercourses.

Geelong Field

Naturalists Club Inc

11/1/10

Little investigation has been undertaken in respect of the

hydrologic and related geochemical systems operating in the

designated urban growth area.

The work that has been undertaken points to potentially significant

issues with regard to relatively shallow saline groundwater in

areas to be subject to development.

The great increase in impervious surfaces will increase surface



TABLE 1 Submissions Relating to the ACEP SWMS

Submittor Date Key Issues Raised by Submittors

runoff.

More thorough and sustained scientific investigation into the

hydrologic systems and inter-relationships with the proposed

urban development ought to be undertaken prior to

implementation of the PSP, particularly given the potential for

changed hydrology to impact on the neighbouring Ramsar

wetlands.

Concerns over impacts of extra runoff water from upslope

development flooding farmland.

W&J Robertson 4/1/10

Drainage depression leading directly into their land (presumably

that so marked on the PSP flowing east-northeasterly from west of

Barwon Heads Road to Groves Road).

6. Information Used and Relied Upon

To prepare this statement I have relied on:

• the information provided to me by CoGG as part of the ACEP SWMS review

process (including existing topographic data and aerial photography);

• discussions with Bonacci Water, other consultant team members involved in

the ACEP PSP and Council officers as part of the SWMS review process;

• existing groundwater bore records (refer to Appendix B);

• the submissions as listed in Table 1.



7. Response to Issues Raised

7.1 Designing for the Habitat Requirements of the Growling Grass Frog

Although the Growling Grass Frog has not been identified within the precinct by

targeted surveys carried out during the ACEP investigations, it is accepted that there

is the potential for the species to be present, especially if appropriate habitat is

created.

Best practice waterway environment design normally attempts to maximise habitat

diversity and quality according to known or expected species and their requirements.

The SWMS has only dealt with conceptual waterway design to date but there is a

clear emphasis on protecting water quality, avoiding direct pipe connections to

waterways, and maintaining existing flood hydrology, all of which are fundamental

building blocks for habitat quality and diversity.

Whilst some compromises may need to be made to suit engineering and development

constraints, it is possible to integrate the habitat requirements of this species into

future stormwater and waterway design, especially along the Armstrong Creek

corridor. The new waterway proposed downstream of Horseshoe Bend Road would

be the special focus of such an objective.

Inclusion of this objective would tend to favour the creation of wetlands with open

water pool zones rather than linear bioretention basins which are normally dry.

In areas with flat drainage gradients such as across much of the ACEP (and especially

downstream of Horseshoe Bend Road), wetlands and ponds are normally favoured on

engineering design grounds as well, simply to resolve lack-of-grade issues. In the

Charlemont Road area this will be even more important because of the need to protect

remnant trees by avoiding significant filling of land.



7.2 Impacts of Recycled Water Supply Provision

Recycled water is water that has been derived from sewerage systems and treated to a

standard that is appropriate for its intended use. Class A1 recycled water is proposed

to be provided to the ACEP by a dual pipe scheme2 from the new Black Rock

Recycled Water Plant.

High salinity is not normally an issue with a recycled water supply intended for

internal building and garden irrigation uses as in the ACEP. High salinity would

effectively preclude its use for these purposes. High nutrient loads are however a

significant issue with this supply.

Barwon Water have advised that:

(a) targets have been set for 500 mg/L TDS salinity for the Class A supply from

the new Black Rock Recycled Water Plant. This salinity is low and well within

the freshwater range (refer Section 7.3) and suitable for the intended uses.

(b) As part of the new Black Rock Recycled Water Plant achieving Class A

validation by the EPA and scheme approval by the DHS, Barwon Water must

complete a Health and Environment Management Plan (HEMP). The

requirement for this plan is addressed in the EPA publication 1015 ‘Dual Pipe

Water Recycling Schemes – Health and Environmental Risk Management’.

(c) Barwon Water is currently investigating the environmental risk by undertaking

a land capability assessment (LCA). The LCA is an important part of the

HEMP and it will assess the environmental sustainability of the Armstrong

Creek area using recycled water, particularly Class A recycled water via a dual

pipe for the purposes of garden watering and toilet flushing. The LCA will

effectively determine the sustainable level of salinity of Class A recycled water

and how its applications be managed.

1 Class A is a health-based microbiological standard for recycled water quality. Class A criteria do not include environmental quality parameters such as salinity or nutrient limits. 2 A dual pipe scheme is an urban water recycling scheme where recycled water is provided to householders for certain uses via a reticulation system that is separate from the drinking water supply. It is sometimes referred to as a ‘third pipe scheme’.



(d) The environmental risk assessment forms a critical component in the selection

of an appropriate treatment process (e.g. for the reduction of salinity), the

design of the development (layout of reticulation system, stormwater

management) and the informing of residents on the appropriate management of

recycled water.

The quality of the Class A recycled water supply in the ACEP is entirely an issue for

Barwon Water to respond to. In my opinion a statement should be provided by

Barwon Water to the Advisory Committee to this effect and that must include

guidelines for the application and use of the supply by the end user.

Importation and use of Class A recycled supply on residential allotments is an issue

that the SWMS has to accept as a given constraint, having regards to the Barwon

Water proposal.

The review report acknowledges that high nutrients loads are expected to be a

characteristic of such supply and this in turn will influence final design of stormwater

quality management assets in the ACEP.

As it competes directly with roofwater/stormwater sources for many of the same end

uses, the imposition of the recycled water supply also significantly limits what the

SWMS can do by way of minimising the hydrologic impacts of additional freshwater

runoff associated with increase in impervious surfaces. The SWMS strongly supports

the use of rainwater tanks across the ACEP but under present legislation and

regulations there is no mechanism to guarantee they will be installed and used

effectively.

Given the sensitivity of receiving environments, and the threat posed by elevated

nutrient loads in the recycled water supply, future stormwater drainage design should

focus on ways and means to maximise disconnection of urban drainage from the

waterway environments and ensure effective treatment before discharge occurs.



These objectives are fully integrated in the SWMS. A key provision is for no direct

connection between urban drains and receiving waterways and for the use of

distributed treatment/detention systems emphasising infiltration.

Detail design to size stormwater quality treatment systems should also make provision

for potential higher inlet nutrient loads. To my knowledge there has been no

significant published research into this issue, nor recommendations made by

responsible authorities such as Barwon Water and Melbourne Water.

Instead the usual design approach in areas mandated for Class A recycled water

supply has been to adopt a higher level of nutrient removal as a performance standard.

For example, best current practice stormwater treatment standards for nutrient

removal are 45% removal of the typical urban nutrient load. To allow for the recycled

supply impacts this standard could be lifted to, for example, 47.5% or 50% removal.

The Bonacci Water SWMS modelling indicates removals of 77% for Total

Phosphorus (TP) and 56% for Total Nitrogen (TN) across the ACEP, both of which

will suffice to deal with potential recycled water supply issues.

Appropriate design of stormwater conveyance and treatment systems is the only

response open to the SWMS.

It is also necessary for the recycled water supply to be used responsibly in the roll-out

areas. External uses of the water present the greatest risk because of the proximity to

the stormwater drainage system. By comparison, internal building uses of the recycled

water are low risk as they are connected to the sewerage system. Measures such as

sub-surface drip irrigation systems and no carwashing unless over a porous surface

are important. Barwon Water has the responsibility for ongoing education and

monitoring of the usage of the recycled water supply in the ACEP.



7.3 Shallow Saline Groundwater

Water quality status in terms of salinity (Total Dissolved Solids-TDS) is normally

considered to be as follows:

“Fresh” water TDS <= 2,000 mg/l

“Brackish” water TDS 2,000-10,000 mg/l

“Saline” water TDS >10,000 mg/l

In practice the boundaries between these categories are not so distinct.

The only available water quality data for registered bores in the ACEP (see Appendix

B) indicates an average TDS of about 10,000 mg/l which infers it is brackish to saline

as would be expected in this geology and lowland setting.

The bores also show depth to groundwater ranges from about 3-6 m below existing

surface. That depth can be expected to reduce towards the valley base of Armstrong

Creek and towards the receiving freshwater and estuarine wetland systems of Hospital

Swamp and the tidal Lake Connewarre.

Available topographic data and aerial photography show indications of groundwater

seepage or waterlogging (as evidenced by vegetation patterns) below about 1-1.2 m

AHD, downstream (east) of Barwon Heads Road. Invert levels of the channel of

Armstrong Creek at Barwon Heads Road and the entry to the wetland systems some

250 m downstream are about 1.0 m and 0.5 m AHD respectively. Saline impacts are

not evident at Barwon Heads Road with freshwater aquatic species dominant in this

part of the waterway so the expectation is for groundwater levels to be generally

below 1 m AHD. However water quality in the creek would be expected to tend

towards brackish conditions at times of zero or very low stream flow. Once

established, freshwater aquatic plant species are usually tolerant of quite wide

variations in salinity on a seasonal basis.



Existing information and field inspection indicates that groundwater depth and

salinity is not expected to be a significant constraint on design of freshwater-

dominated waterway and stormwater management systems through and upstream of

Barwon Heads Road.

Notwithstanding this expectation it is reasonable for specific recommendations to be

made for testing and monitoring of groundwater as part of the future design phase for

the ACEP SWMS. In particular the design of the future Armstrong Creek waterway

must be properly informed by knowledge of groundwater level and quality regimes.

In this regard such investigations are already underway with the commencement of

concept design work on the Armstrong Creek waterway and environs. Installation of

eight geotechnical test bores is imminent between Horseshoe Bend Road and Barwon

Heads Road. These bores are to be constructed, surveyed and capped off to act as

longer term groundwater monitoring bores.

The testing regime for the bores varies with time and is as set out in Table 2.

TABLE 2 Recommended Groundwater Testing and Monitoring for Armstrong Creek

bores

Testing frequency Parameter

Months 1-6 Months 6-12 Thereafter

Groundwater standing level (m AHD) Monthly 3 monthly 6 monthly 3

Conductivity (EC) Monthly 1,2 3 monthly 6 monthly 3

TDS (mg/l) Monthly 1,2 - -

pH, NH3, NO3+NO2, TKN, TN, ortho-P, TP 6-monthly 6-monthly 6-monthly 3

major anions and cations (Na, K, Ca, Mg, Cl,

SO4, CO3)

Once only - -

metals scan for Iron, Copper, Cadmium, Lead

and Zinc at a minimum

Once only - -

Pesticides Once only - -



1. once the relationship between conductivity and TDS is established, then

conductivity only should suffice for future tests if relationship is shown to be

consistent.

2. duration of monthly monitoring and testing will be dictated by what the results

are showing.

3. depending on the results of monitoring after the first 12 months, a reduced set

of parameters may be adopted for the bores and testing of some bores may be

discontinued for longer term monitoring purposes. It is anticipated that testing

of about 50% of the bores may be discontinued after 24 months. The need for

and extent of ongoing groundwater monitoring should be revisited as part of 5

yearly review reports.

7.4 Raised Groundwater Levels and Impacts on Ramsar Wetlands

Increase in impervious surfaces causing increased surface runoff volumes, and

importation of recycled water supply are seen as threats in some submissions. The

inference is that increased accessions to groundwater will eventuate leading to rises in

saline water tables and consequential impacts on receiving Ramsar Wetlands.

There is no reason to expect increased saline water table levels across the ACEP for

the following reasons:

• Given that rainfall input is constant, the nett effect of increased surface runoff

is reduced supply to groundwater and reduced evapotranspiration.

• The recycled water supply will be costly to use. It is difficult to imagine

widespread application of this supply in excess of that needed to satisfy normal

garden irrigation requirements (ie., watering normally satisfies

evapotranspiration and plant growth needs only).

• Diverse and distributed service trench installations across the ACEP (drainage

pipes, sewer pipes, potable and recycled water mains, telecommunications etc)

all increase subsurface drainage efficiency and tend to lower water tables,

unless specific counter-measures are adopted to prevent this from happening



(eg., sealing or plugging trenches to inhibit groundwater interception and

conveyance).

At the receiving end downstream of Barwon Heads Road the nett effect of

urbanisation will be increased delivery of (treated) freshwater via the drainage

systems cf. existing conditions. This will remain dominated by seasonal variability.

The Bonacci Water SWMS modelling showed that mean annual surface runoff would

be reduced by more than 30% cf. conventional urban development. This still however

results in increased discharge of (fresh) surface runoff to Armstrong Creek and the

wetlands cf. existing pre-development conditions.

Additional reductions in freshwater runoff could be achieved through widescale

adoption of rainwater tanks across the ACEP, but that response is effectively stymied

by the recycled water supply competing for the same uses. The SWMS is limited to

strongly encouraging the voluntary use of rainwater tanks.

Although as a generalisation there is no expected increase in water table levels across

the ACEP, it is possible for local changes to water tables to occur around features

such as constructed wetlands. The potential for such changes and need for any

compensatory works are part and parcel of normal best practice investigation and

design.

The groundwater monitoring bores to be established along the creek downstream of

Horseshoe Bend Road to Barwon Heads Road will be important tools for future

design.



7.5 Armstrong Creek Waterway Corridor Width

As summarised in Section 4.2, the ACEP SWMS Review report concluded that whilst

in theory a 32 m wide corridor could suffice to address the primary stormwater and

flood management requirements, an average 70 m corridor width along Armstrong

Creek would be preferable, to provide a waterway environment with more diverse

flora/fauna/geomorphologic/landscape/recreational values.

In my opinion it follows that the submission by the Geelong Field Naturalists Club

Inc for 70 m wide buffers to the creek (hence a corridor width of 140 m+) cannot be

supported on waterway management grounds.

7.6 Increased Flooding in Groves Road Area

(a) Upslope flooding

The concerns over increased flooding of lands from upslope developments in the

ACEP area east of Barwon Heads Road (Sub-Precinct E6) are certainly legitimate, but

the Bonacci Water SWMS has already addressed these issues in Section 5.3.15.

Special recommendations are made for three integrated water quality

treatment/detention storage systems on the margins of, but within the Barwon River

floodplain. These are sized to maintain existing peak rural runoff rates and to ensure

water quality objectives are complied with, for runoff from the 12.36 ha of proposed

urban development upslope.

However it is acknowledged that:

• no specific reference is made in the SWMS as to how the discharges from

those treatment systems would be conveyed through the downslope land to the

ephemeral waterway north of Groves Road;

• although the Bonacci Water SWMS modelling shows nearly 40% reduction in

annual discharge volume cf. conventional development, some increase in



seasonal and annual runoff volumes cf. existing conditions cannot be avoided

for the reasons expressed previously.

The drainage connection issue could be dealt with in a number of ways including:

• Separate new open drainage lines could be constructed on agreed alignments

from each system and covered with easements;

• The three systems could be interconnected with a combined new open drainage

line constructed on an agreed alignment and covered with an easement,

possibly within or parallel to the Alcoa Easement.

The appropriate solution for drainage management and outfall from sub-Precinct E6

(and indeed any other sub-precinct) is a matter for future detail design during the

planning permit stage but should be the subject of negotiations with the landowners

concerned.

Given that it will be effectively treated, the additional water should also be considered

as a potential resource that could be exploited by landowners for irrigation and not

just viewed as a potential nuisance.

(b) The Drainage Depression

In regard to the Drainage Depression listed in the Robertson submission, presumably

that is the one so marked on the PSP flowing east-northeasterly from west of Barwon

Heads Road to Groves Road. If so then that waterway and all development catchment

area is outside the ACEP and hence beyond the scope of this statement.

However future development in that precinct would be expected to include suitable

modification of the ephemeral waterway east of Barwon Heads Road along Groves

Road to address issues associated with runoff from that part of the PSP.



8. Summary and Conclusions

Growling Grass Frog Habitat Needs

Although the Growling Grass Frog has not been identified within the precinct by

targeted surveys carried out during the ACEP investigations, it is accepted that there

is the potential for the species to be present, especially if appropriate habitat is

created.

Whilst some compromises may need to be made to suit engineering and development

constraints, it is possible to integrate the habitat requirements of this species into

future stormwater and waterway design, especially along the Armstrong Creek

corridor. The new waterway proposed downstream of Horseshoe Bend Road would

be the special focus of such an objective.

Inclusion of this objective would tend to favour the creation of wetlands with open

water pool zones rather than linear bioretention basins which are normally dry.

Impacts of Recycled Water Supply Provision

High salinity is not normally an issue with a recycled water supply intended for

internal building and garden irrigation uses as in the ACEP. High salinity would

effectively preclude its use for these purposes. High nutrient loads are however a

significant issue with this supply.

Barwon Water have advised that targets have been set for 500 mg/L TDS salinity for

the Class A supply from the new Black Rock Recycled Water Plant. This salinity is

low and well within the freshwater range and suitable for the intended uses.

The quality of the Class A recycled water supply in the ACEP is entirely an issue for

Barwon Water to respond to. In my opinion a statement should be provided by

Barwon Water to the Advisory Committee to this effect and that must include

guidelines for the application and use of the supply by the end user.



Importation and use of Class A recycled water supply on residential allotments is an

issue that the SWMS has to accept as a given constraint. Objectives to address

sensitivity of receiving environments, and the threat posed by elevated nutrient loads

in the recycled water supply, are fully integrated in the SWMS. Key provisions are for

no direct connection of urban drains to receiving waterways, for the use of distributed

treatment/detention systems emphasising infiltration, and for nutrient removal in

excess of normal best practice.

It is also necessary for the recycled water supply to be used responsibly in the roll-out

areas. Barwon Water has the responsibility for ongoing treatment compliance,

education and monitoring of the usage of the recycled water supply in the ACEP.

Shallow Saline Groundwater

Existing information and field inspection indicates that groundwater depth and

salinity is not expected to be a significant constraint on design of freshwater-

dominated waterway and stormwater management systems through and upstream of

Barwon Heads Road.

Notwithstanding this expectation it is reasonable for specific recommendations to be

made for testing and monitoring of groundwater as part of the future design phase for

the ACEP SWMS. In particular the design of the future Armstrong Creek waterway

must be properly informed by knowledge of groundwater level and quality regimes.

Installation of eight geotechnical test bores is imminent between Horseshoe Bend

Road and Barwon Heads Road. These bores are to be constructed, surveyed and

capped off to act as longer term groundwater monitoring bores. The testing regime for

the bores varies with time and is as set out in Table 2 and its accompanying footnotes.

Raised Groundwater Levels and Impacts on Ramsar Wetlands

There is no reason to expect increased saline water table levels across the ACEP due

to urbanisation impacts or importation of recycled water supply.



The Bonacci Water SWMS modelling showed that mean annual surface runoff would

be reduced by more than 30% cf. conventional urban development. This still however

results in increased discharge of (fresh) surface runoff to Armstrong Creek and the

wetlands cf. existing pre-development conditions. At the receiving end downstream of

Barwon Heads Road the nett effect will be increased delivery of (treated) freshwater

via the drainage systems cf. existing conditions. This will remain dominated by

seasonal variability.

Additional reductions in freshwater runoff could be achieved through widescale

adoption of rainwater tanks across the ACEP, but that response is effectively stymied

by the recycled water supply competing for the same uses. The SWMS is limited to

strongly encouraging the voluntary use of rainwater tanks.

Although as a generalisation there is no expected increase in water table levels across

the ACEP, it is possible for local changes to water tables to occur around features

such as constructed wetlands. The potential for such changes and need for any

compensatory works are part and parcel of normal best practice investigation and

design.

Armstrong Creek Corridor Width

As summarised in Section 4.2, the ACEP SWMS Review report concluded that whilst

in theory a 32 m wide corridor could suffice to address the primary stormwater and

flood management requirements, an average 70 m corridor width along Armstrong

Creek would be preferable, to provide a waterway environment with more diverse

flora/fauna/geomorphologic/landscape/recreational values.

In my opinion it follows that the submission by the Geelong Field Naturalists Club

Inc for 70 m wide buffers to the creek (hence a corridor width of 140 m+) cannot be

supported on waterway management grounds.



Increased Flooding in Groves Road Area

(a) Upslope flooding

The Bonacci Water SWMS has addressed these issues in Section 5.3.15. Assets are

included on the margins of, but within the Barwon River floodplain, to maintain

existing peak rural runoff rates and to ensure water quality objectives are complied

with for runoff from the 12.36 ha of proposed urban development upslope.

However it is acknowledged that:

• no specific reference is made in the SWMS as to how the discharges from

those treatment systems would be conveyed through the downslope land to the

ephemeral waterway north of Groves Road;

• although the Bonacci Water SWMS modelling shows nearly 40% reduction in

annual discharge volume cf. conventional development, some increase in

seasonal and annual runoff volumes cf. existing conditions cannot be avoided

for the reasons expressed previously.

The drainage connection issue could be dealt with in a number of ways including

construction of one or more new drains on agreed alignments and covered with

easements. The appropriate solution is a matter for future detail design but should be

the subject of negotiations with the landowners concerned.

Given that it will be effectively treated, the additional water should also be considered

as a potential resource that could be exploited by landowners for irrigation and not

just viewed as a potential nuisance.

(b) The Drainage Depression

The Drainage Depression marked on the PSP flowing east-northeasterly from west of

Barwon Heads Road to Groves Road and its catchment lie outside the ACEP and

hence beyond the scope of this statement.



9. Declaration

In preparing this statement I have made all the enquiries that I believe to be desirable

and appropriate, and that no matters of significance that I regard as relevant have to

my knowledge been withheld from the Advisory Committee.

Neil M Craigie BE Civil, MengSci, MIEAust, CPEng 29 January 2010



10. Abbreviations And Definitions AHD Australian Height Datum. Common base for all survey levels in Australia.

Refers to height in metres above mean sea level. ARI Average Recurrence Interval. The average length of time in years between two

floods of a given size or larger Ephemeral Waterways which flow for only short periods of time after significant rainfall

events. Also refers to wetlands which are either rarely inundated or only inundated for a very short period of time.

Evapotranspiration The loss of water to the atmosphere by means of evaporation from free water surfaces (eg. dams or lakes or wetlands) or by transpiration by plants

Groundwater All water stored or flowing below the ground surface level Ha Hectare (10,000 square metres) Km Kilometre (1000 metres) M3/s Unit of discharge = cubic metre/second ML Megalitre (1000 cubic metres) Pond A small artificial body of open water (eg. dam or small lake) Retarding basin A flood storage dam which is normally empty. May contain a lake or wetland in

its base Sedimentation basin (sediment pond)

A pond that is used to remove sediments from inflowing water mainly by settlement processes. Edge zones may have similar appearance to wetland margins.

Surface water All water stored or flowing above the ground surface level Swale A drainage line with essentially trapezoidal cross-sectional form. Can have

rocky or soil bed form, be fully vegetated with indigenous species, or grassed. The base can be fitted with a filter zone to further assist in pollutant removal (termed a bio-retention swale). Foundations can be ripped to encourage seepage losses in suitable soils.

Waterlogging Term used to describe saturated surface soil conditions where some free surface water may also be present

Wetland A transitional area between land and water systems which is either permanently or periodically inundated with shallow water and either permanently or periodically supports the growth of aquatic macrophytes (eg. swamp, marsh, fen, bog)

11. References Coffey 2006- Report on Geotechnical Investigations for Pinnacle Valley Development, (Report M6400/1-AA, 11 July 2006) Institution of Engineers, Australia (1987), Australian Rainfall and Runoff, A Guide to Flood Estimation Institution of Engineers, Australia (2006), Australian Runoff Quality Guidelines Stormwater Committee, Victoria (1999), Urban Stormwater Best Practice Environmental Management

Guidelines. Pub. CSIRO Craigie NM, Seymour BS and Condina P (31 July 2006), Pinnacle Valley Estate Development Merrijig,

Surface Water Management Strategy Stage 1 Preliminary Investigation, for Far East Consortium



Appendix A Statement Of Qualifications And Experience Name: Neil McKinnon Craigie Address: 15 Mulawa Street Croydon North, Vic., 3136 Business Phone/Fax: 03 9725 1053 Email: [email protected] Professional Qualifications:

B.E. (Civil), Monash University 1975 Grad. Course in Engg. Hydrology, UNSW 1976

M.Eng. Sci., Monash University 1981 Professional Background:

1974 Joined Dandenong Valley Authority (DVA) 1980 Appointed as Design Engineer 1984 Appointed as Design and Investigation Engineer controlling hydrologic

and hydraulic investigations, project design and engineering consultancy services

1989 Commenced private practice as a waterway management consultant. Current Occupation: Waterways Management Consultant

trading as Neil M Craigie Pty Ltd Affiliations: Member, Institution of Engineers Australia (MIEAust, CPEng)

Member, River Basin Management Society (RBMS) Experience: I have extensive experience in:

• river basin management, • assessment and design of restoration works for degraded and/or unstable

natural waterway systems, • assessment and design of mitigation works to address the effects of

urbanisation on waterway systems, • investigation and design of drainage and flood management schemes of all

forms and sizes in both urban and rural settings, • troubleshooting and remedial design in urban drainage systems. • investigation, design and ongoing management of wetland, lake and tidal

waterway systems Whilst with the DVA, I directed all hydrologic and hydraulic investigations, project design and consultancy services. I led the preparation of standards for stream restoration work and developed innovative techniques for evaluation and appraisal of waterway management problems. I have further refined and applied these techniques



since commencing private practice, in major studies throughout Victoria and in Far North and South-East Queensland. In recent years, I have undertaken work in the field of environmental flows, providing hydraulic and waterway management input to multi-disciplinary teams. I was a team member for the Environmental Flow Assessment for the Lower Thomson and Macalister Rivers in Victoria (CRC Freshwater Ecology, 1999). Since 2000, I have assisted Dr Sandra Brizga on the environmental flow studies carried out for the Water Allocation and Management Plans (WAMPs) on the Pioneer and Logan Rivers, for the Water Resource Plans (WRP’s) on the Mary and Maroochy Rivers in Queensland, and the River Processes Study on the Mary River. Each of these studies is a major multidisciplinary undertaking involving specialists from a range of disciplines, including hydrology, hydraulics, geomorphology, water quality, and ecology (aquatic and riparian vegetation, macroinvertebrates, fish, and other vertebrates such as turtles, platypus and dugong). I have carried out and/or directed numerous hydrologic and hydraulic studies, utilising computer based models. I have particular expertise in retarding/retention basin design, several examples of which have featured novel outlet works designed to counteract high debris loads, mitigate sediment discharge, provide water quality treatment, and dissipate very high flow velocities. In the field of management of natural waterway and floodplain systems, I and my associates have collaborated on a series of complex hydro-geomorphological investigations. These studies involved integration of unsteady-state two dimensional hydraulic modelling and fluvial geomorphology analyses to develop waterway management plans which recognise and address the governing physical processes (for example, the Tambo River at Bruthen, Badger Creek through Healesville Sanctuary, and Glenelg River sand transport studies). In the urban areas I have been closely involved in the development and preparation of municipal/agency stormwater management plans across the greater Melbourne area. I and my associates are continuing to play leading roles in conceptual planning and design of stormwater quantity and quality management systems involving open waterways, wetlands and lakes in many of the large residential estates being developed in greater Melbourne since the late 1990’s (for example, Caroline Springs, The Waterways Estate, Tenterfield Estate, The Boardwalk Estate, Berwick Springs Estate, Beaumont Waters Estate, Torquay Sands, Lakeside at Pakenham, Pt Cook Gardens Estate, Lincoln Heath Estate, Marriott Waters, Martha Cove, Highlands Estate). I am also active at the regional level with similar water management system planning (for example; Paynesville, Port Fairy, Warrnambool, Bendigo, Geelong/Bellarine Peninsula, Mornington Peninsula, Phillip Island/San Remo, Castlemaine, Traralgon, Warragul, Taggerty).



In conjunction with associates in the field of stormwater and wastewater quality treatment and aquatic biology, I have developed innovative approaches to design of stormwater quality management systems and all aspects of water sensitive urban design, and have applied these in a variety of urban, semi-urban and rural settings. In conjunction with my associates, I have won UDIA Awards for Excellence for Water Sensitive Urban Design and Residential Development in 2000, 2002, 2003, 2004, 2005, 2007, 2008 and 2009 and the SIAV Award for Stormwater Innovation in 2004 and 2005 (2). In the rural areas I have jointly carried out investigations into redesign opportunities for irrigation drainage systems to mitigate sediment and nutrient loads, for Goulburn-Murray Water. This work culminated in the design and construction of a major artificial wetland system serving the Muckatah Depression Drainage Scheme in Northern Victoria. This project has since won the IEAust Engineering Excellence Award. Since commencing private practice in 1989 I have also gained considerable experience as an expert witness, preparing and presenting numerous submissions to VCAT and various Planning Panels on drainage, waterway and floodplain management implications of proposed development projects throughout Victoria. Neil M Craigie



Appendix B Existing Groundwater Information Information obtained from the Victorian Groundwater Database indicates just two registered bores are located in the ACEP area as shown on Figure B.1. Both bores are located well upslope from the Armstrong Creek corridor and roughly flank the Alcoa Easement. These bores were constructed in 1982 and the test records taken in December 1982 are listed in Figure B.2. The recorded depths to standing water level ranged from about 6 m to 2.7 m below natural surface levels. The salinity readings average about 10,000 mg/l which roughly equates to about 1/3 sea water. The dearth of groundwater records in this area is probably reflective of the fact that the groundwater is of poor quality in regard to salinity and there are corresponding limits to its usefulness for agricultural purposes.



Figure 1

Victorian Groundwater Database Information

showing registered bore locations in the ACEP

(refer to Figure 2 for records taken in 1982)



Figure 2

Victorian Groundwater Database Information showing test records for the

two registered bore locations in the ACEP

Documents

STATEMENT OF EXPERT EVIDENCE CITY OF … Corp... · Armstrong Creek East Precinct Structure Plan City of Greater Geelong PS Amendment C206 ii Neil M Craigie Pty Ltd TABLE OF CONTENTS