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CAMDEN HAVEN FLOODPLAINRISK MANAGEMENT STUDY

Looking westwards along the Camden Haven River and its entry into the Pacific Ocean.

Final ReportMarch 2004

Bewsher Consulting Pty Ltd

CAMDEN HAVEN FLOODPLAIN RISK MANAGEMENT STUDY BEWSHER CONSULTING PTY LTD March 2004 J916-CHFPM-Study-V5.doc

Hastings Council

CAMDEN HAVEN FLOODPLAIN RISK MANAGEMENT STUDY

FINAL REPORT

MARCH 2004

Prepared by:

BEWSHER CONSULTING PTY LTD

P O BOX 352 EPPING NSW 1710

Telephone (02) 9868 1966 Facsimile (02) 9868 5759

Email [email protected] ACN 003137068


PREFACE The Camden Haven Floodplain Risk Management Study and Plan was prepared by Bewsher Consulting Pty Ltd for Hastings Council. Funding and technical assistance was provided for the study through the Department of Infrastructure, Planning and Natural Resources (formerly Department of Land and Water Conservation) under the State Government’s Floodplain Management Program. Funding was also provided by the Commonwealth Department of Transport and Regional Services, through its National Landcare and Natural Disaster Risk Management Programs. On 21st March 2004, Council resolved to adopt the Plan as follows: 1. That the Camden Haven Floodplain Risk Management Study and Plan 2004

(excluding the planning measures) prepared on Council’s behalf by Bewsher Consulting Pty Ltd be adopted.

2. That the Draft Camden Haven Floodplain DCP be adopted in principle and

processed in accordance with Part III of the EPA Act. 3. That the Hastings LEP 2001 be amended to incorporate the model floodplain

management clauses as recommended by the Camden Haven Floodplain Management Plan.

4. That there be further consultation with landowners in the Camden Haven on the

Plan, particularly in relation to the risk mapping and the wording connected to the risk classifications.


TABLE OF CONTENTS Page

_____________________________________________________________________________________________________

EXECUTIVE SUMMARY 1 1. INTRODUCTION 6

1.1 OBJECTIVES OF THIS STUDY 6 1.2 THE STUDY AREA 6 1.3 THE GOVERNMENT’S FLOODPLAIN MANAGEMENT PROCESS 8 1.4 FORMAT OF REPORT 9

2. BACKGROUND INFORMATION 10 2.1 PHYSICAL DESCRIPTION 10 2.2 EXISTING LAND USE 10 2.3 EXISTING VEGETATION 11 2.4 ACID SULPHATE SOILS 13 2.5 HERITAGE 15 2.6 POPULATION CHARACTERISTICS 17 2.7 DEVELOPMENT TRENDS & STRATEGIC PLANNING DIRECTIONS 21

3. REVIEW OF PREVIOUS FLOOD INVESTIGATIONS 23

3.1 CAMDEN HAVEN FLOODPLAIN MANAGEMENT STUDY 23 3.2 COUNCIL’S FLOODPLAIN MANAGEMENT STRATEGY 26 3.3 NORTH HAVEN DRAINAGE STUDY 26 3.4 NORTH HAVEN DRAINAGE INVESTIGATION 27 3.5 REVIEW OF CAMDEN HAVEN FPM STRATEGY – STAGE 1 27 3.6 REVIEW OF CAMDEN HAVEN FPM STRATEGY – STAGE 2 28 3.7 CAMDEN HAVEN ESTUARY MANAGEMENT STUDY 28

4. EXISTING FLOOD BEHAVIOUR 29

4.1 HISTORY OF FLOODING 29 4.2 DESCRIPTION OF THE FLOOD PROBLEM 29 4.3 SUMMARY OF PROPERTY INUNDATION 30 4.4 FLOOD RISK MAPPING 35

5. FLOOD DAMAGES ASSESSMENT 38 5.1 FLOOD DAMAGES DATABASE 38 5.2 TYPES OF FLOOD DAMAGE 40 5.3 BASIS OF FLOOD DAMAGE CALCULATIONS 41 5.4 SUMMARY OF FLOOD DAMAGES 41

6. COMMUNITY CONSULTATION 45 6.1 CONSULTATION PROCESS 45 6.2 FLOOD WORKING PARTY 45 6.3 ADVERTISING THE STUDY 46 6.4 COMMUNITY QUESTIONNAIRE 47 6.5 LIAISON WITH GOVERNMENT AGENCIES AND GROUPS 51 6.6 POSTER DISPLAY, INFORMATION DAY & PUBLIC MEETING 55 6.7 PUBLIC EXHIBITION OF DRAFT PLAN 57


TABLE OF CONTENTS (cont) Page

___________________________________________________________________ 7. PLANNING ISSUES & POLICIES 58

7.1 INTRODUCTION 58 7.2 STATE ENVIRONMENTAL PLANNING POLICIES 58 7.3 REGIONAL ENVIRONMENTAL PLANS 59 7.4 ADVISORY CIRCULARS 60 7.5 LOCAL ENVIRONMENTAL PLANS (LEP’s) 61 7.6 DEVELOPMENT CONTROL PLANS (DCP’s) 63 7.7 COUNCIL POLICIES 67 7.8 SECTION 94 CONTRIBUTIONS PLANS 68 7.9 SECTION 149 CERTIFICATES 68

8. FLOOD WARNING & EMERGENCY MANAGEMENT ISSUES 72

8.1 BENEFITS 72 8.2 FLOOD WARNING 73 8.3 EMERGENCY MANAGEMENT ISSUES 80 8.4 FLOOD AWARENESS 86

9. FLOODPLAIN MANAGEMENT CONSIDERATIONS 96

9.1 SELECTION OF THE FLOOD PLANNING LEVEL 96 9.2 TYPES OF MEASURES AVAILABLE 97 9.3 RANGE OF MEASURES CONSIDERED 98 9.4 ASSESSMENT CRITERIA 99

10. POTENTIAL FLOODPLAIN MANAGEMENT MEASURES 101 10.1 RING LEVEE AROUND NORTH HAVEN 101 10.2 SEAL NORTH TRAINING WALL 102 10.3 RING LEVEE AROUND DUNBOGAN 103 10.4 IMPROVED FLOOD ACCESS FOR DUNBOGAN 104 10.5 LEVEE AROUND PART OF LAURIETON 105 10.6 FILL AREA OF LAND SOUTH OF LAURIETON 106 10.7 DUNBOGAN CANAL ESTATE 107 10.8 FILL SMALL AREA WITHIN LAURIETON 107 10.9 FILL NORTH HAVEN TO QUEENS LAKE 108 10.10 HIGH LEVEL ROAD AROUND NORTH HAVEN 108 10.11 SMALL LEVEE IN LAKEWOOD VILLAGE 109 10.12 REMOVAL OF ROCK BAR NEAR ENTRANCE 110 10.13 DREDGE STINGRAY CREEK 110 10.14 CHANNEL FROM QUEENS LAKE TO OCEAN 111 10.15 VOLUNTARY PURCHASE 113 10.16 VOLUNTARY HOUSE RAISING 113 10.17 FLOOD PROOFING INDIVIDUAL PROPERTIES 115 10.18 ZONING AND DEVELOPMENT CONTROLS 115 10.19 IMPROVED FLOOD WARNING SYSTEM 116 10.20 IMPROVED EMERGENCY MANAGEMENT PROCEDURES 118 10.21 IMPROVED PUBLIC AWARENESS 118


TABLE OF CONTENTS (cont) Page

___________________________________________________________________ 11. REFERENCES 125 12. GLOSSARY 128 APPENDICES Appendix A - Newsletter, Questionnaire & Questionnaire Results Appendix B - Summary of Submissions Received from Public Exhibition

of Draft Reports Appendix C - Proposed Approach to Floodplain Planning Appendix D - Recommended Changes to Existing Planning Instruments Appendix E - General Provisions for Inclusion in Council’s

Flood Prone Land Policy Appendix F - Proposed Flood Risk Management Development Control Plan


LIST OF TABLES Page ___________________________________________________________________ Table 2.1 – Analysis of Census Information: 1986 to 1996 19 Table 3.1 – Structural Measures Considered in the 1991 Study 24 Table 3.2 – Non Structural Measures considered in the 1991 Study 25 Table 4.1 – Residential Property Affected by Flooding 31 Table 4.2 – Commercial & Industrial Properties Affected by Flooding 31 Table 4.3 – Location of Residential Homes Affected by Flooding 32 Table 4.4 – Inundation Depths for Homes Affected by the 100 year Flood 34 Table 4.5 – Provisional Flood Hazard for Residential Property 35 Table 5.1 – Properties Included in the Database 38 Table 5.2 – Potential Flood Damages under Existing Conditions 43 Table 5.3 – Predicted Flood Damages under Existing Conditions 43 Table 6.1 – Flood Working Party Representatives 46 Table 6.2 – Distribution of Questionnaires and Response Rate 47 Table 6.3 – Floodplain Management Measures Favoured by the Community 50 Table 6.4 – Floodplain Management Measures Opposed by the Community 50 Table 6.5 – Consultation with Agencies & Interest Groups in the Study Area 52 Table 8.1 – Water Level Gauges within the Catchment 78 Table 8.2 – Caravan Parks Affected by Flooding 84 Table 8.3 – Low Points on Main Access Roads 85 Table 9.1 – Potential Floodplain Management Measures 98 Table 10.1 – Qualitative Assessment Matrix 121 Table 10.2 – Explanation of Assessment Scores for Qualitative Assessment Matrix 122 LIST OF FIGURES ___________________________________________________________________

Figure 1.1 – The Study Area 7 Figure 1.2 – The Floodplain Management Process 8 Figure 4.1 – Camden Haven Flood Risk Areas 37 Figure 5.1 – Types of Flood Damage 40 Figure 5.2 – Components of Flood Damage for Camden Haven 42 Figure 8.1 – Total Number of Residential Homes Affected by Floods 83 Figure 8.2 – Dunbogan Road Access 90 Figure 8.3 – North Haven Road Access 91 Figure 8.4 – Wharf Road, Stewarts River Road Access 92 Figure 8.5 – Kendall Road Access 93 Figure 8.6 – Sample Flood Certificate (unknown floor level) 94 Figure 8.7 – Sample Flood Certificate (known floor level) 95 Figure 10.1 – Floodplain Management Measures Considered 123 Figure 10.2 – Floodplain Management Measures Considered 124

CAMDEN HAVEN FLOODPLAIN RISK MANAGEMENT STUDY 1 BEWSHER CONSULTING PTY LTD March 2004 J916-CHFPM-Study-V5.doc

EXECUTIVE SUMMARY Responsibilities The prime responsibility for planning and management of flood prone lands in New South Wales rests with local government. The NSW Government provides assistance on state-wide policy issues and technical support. Financial assistance is also provided to undertake flood and floodplain management studies, such as the current study, and for the implementation of works identified in these studies. Hastings Council commissioned Bewsher Consulting Pty Ltd to prepare a floodplain risk management study and plan for the Camden Haven River catchment in October 1999. The Camden Haven Estuary Management Committee’s Flood Working Party oversaw the study. This working party consists of Councillors and staff from Hastings Council, officers from the Department of Land and Water Conservation (since July 2003, incorporated into the Department of Infrastructure, Planning and Natural Resources) and State Emergency Service, representatives from the Camden Haven Protection Society, the North Haven Progress Association, Laurieton Chamber of Commerce, Queens Lake Sailing Club, and other community representatives. The Catchment The Camden Haven catchment is located on the mid north coast of New South Wales about 375km north of Sydney. It has a total catchment area of approximately 640 km2, which drains to the ocean via the Camden Haven River. Other major drainage systems include Stewarts River, Stingray Creek and Herons Creek. Most development in the catchment is located towards the downstream end of the river, at Dunbogan, North Haven, Laurieton and West Haven. Much of the land in these localities is particularly low-lying, with many properties as low as RL2.0m AHD. Subsequently, many of the properties are exposed to high flood risks. Other development is located further upstream, at Kew and Kendall. Flooding can be caused by high ocean levels; high rainfall over the catchment (as was the case for the 1929 flood); or a combination of both (as was the case for the 1963 flood). Objectives of the Study The objective of the current study is to prepare a floodplain risk management plan that will minimise the effects of flooding. Specific objectives of the study include: ► a review of previous flood investigations; ► quantification of the flood problem in Camden Haven; ► a review of potential floodplain management measures to reduce the risks of

flooding, especially catchment-wide measures such as flood warning, emergency management and planning controls;


► a consultation program that involves the community through the progress of the study; and

► the development of a recommended floodplain risk management plan for the study area outlining the best measures to reduce flood risks, based on consideration of environmental, social, economic and engineering issues.

Reporting A number of working papers were prepared during the course of investigations. These working papers were prepared to allow the Flood Working Party to monitor the project, and to provide direction where required. Working paper titles are listed below: ► Community Consultation; ► Environmental and Planning Issues; ► Flood Damages; ► Emergency Management, Flood Warning and Flood Awareness; ► Flood Prone Land Policy and Development Control Plan; ► Evaluation of Management Strategies. The various working papers have been consolidated into this study report. In doing so, information provided in the original working papers have been amended to include comments received from the Flood Working Party and from the public display, information day and public meeting, which were held in July/August 2001. The recommendations of the study are outlined in this Executive Summary and are presented in detail in the Floodplain Risk Management Plan. Consultation Community consultation has been an important component of the current study. Consultation has aimed to inform the community about the development of the floodplain management plan, and to collect feedback and ideas on flood behaviour, potential floodplain management measures, and other related issues. The key elements of the consultation process have been as follows: ► regular meetings of the Camden Haven Estuary Management Committee’s Flood

Working Party; ► advertising the study through local papers, distributing newsletters, and providing

details on the Internet; ► distribution of a questionnaire to residents and business owners within the study

area; ► distribution of a questionnaire to relevant Agencies and Interest Groups; ► a poster display, information day and public meeting during the course of the

study; and


► public exhibition of the recommended floodplain risk management plan, prior to formal consideration by Council.

The Flood Problem A flood damages database of potentially flood affected buildings has been prepared for the study area. The database provides details of those properties likely to be inundated in different sized floods and allows the quantification of potential flood damages. Key results from the database indicate that: ► 1,106 residential homes and 70 commercial buildings would be flooded above

floor level in a probable maximum flood; ► 653 residential homes and 46 commercial buildings would be flooded above floor

level in a 100 year flood; ► Of those homes flooded in a 100 year flood, 380 are located at North Haven, 156

located at Dunbogan, 61 located at Laurieton, 49 located at Kendall and rural surrounds, and 7 located elsewhere;

► The majority of homes in Dunbogan (103) are inundated by over 1.0m in the 100 year flood;

► The predicted flood damage in the 100 year flood is $34M, whilst the average annual flood damage is estimated at $2.8M and the present value of flood damages is estimated at $30M.

Flood Risk Mapping & Development Controls The Camden Haven floodplain has been divided into three flood risk areas (high, medium and low), as shown on Figure 4.1. Different development controls are proposed for the catchment, depending on the type of development and the flood risk area that the development is located. The proposed development controls are summarised in Figure 11.1. The high flood risk area is where high flood damages, potential risk to life, or evacuation problems are anticipated. It is recommended that most development is restricted within this area. The medium flood risk area is where there is still a significant risk of flood damage, but where these damages can be minimised by the application of appropriate development controls. The low flood risk area is that area where the risk of flood damage is low. Most land uses would be permitted within this area (subject to other considerations). The Recommended Floodplain Management Measures A range of floodplain management measures has been assessed as part of the Camden Haven Floodplain Risk Management Study. These include measures previously considered for Camden Haven and other measures suggested during the course of the study.


The measures have been assessed in terms of impacts on flooding, environmental implications, economic considerations and other social issues. The recommended measures comprise predominantly non-structural measures. These measures include those that seek to modify property in order to minimise flood damage (for example controls on new development and house raising), and those that seek to improve the community’s response to flooding (for example flood awareness, improved flood warning, and evacuation procedures). These measures were all well supported by the local community. Some minor structural measures are also proposed. The recommended measures have been included in the Camden Haven Floodplain Risk Management Plan, which is presented as a separate document. The principal recommendations are as follows: ► implementation of planning & development Controls, including amendments to

the Hastings LEP, a general floodprone land policy and a more specific flood risk management development control plan (DCP);

► the development and implementation of a public awareness program, including the issue of flood certificates, an information brochure and the establishment of one or more flood markers in the lower part of the catchment;

► improved flood level information in certain parts of the catchment; ► implementation of a comprehensive flood warning scheme, including additional

catchment instrumentation (already implemented), development of predictive computer software (largely completed) and a flood warning dissemination study;

► improved emergency management measures, including the development of an evacuation strategy and flood action plans for caravan parks and motels located within the floodplain;

► improved flood access provisions for Dunbogan and North Haven, to remove low points in the main access roads and provide a constant grade to higher ground;

► a voluntary house raising scheme, commencing with the trial of a pilot scheme of say 10 houses;

► construction of a small levee in Lakewood Village; and ► works to seal the northern training wall; Timing and Funding The total cost of implementing the recommended measures is approximately $1.4M, plus additional expenditure for road raising and house raising. Road raising costs to improve flood access for Dunbogan and North Haven is subject to further investigation and will be dependent on the extent to which access is to be improved and the cost to adjust services and private driveways. An allowance has been provided in the project cost to raise 10 houses as part of a pilot house raising scheme. However, the total number of houses to be included in the overall scheme and the level of financial subsidy to be provided to home owners is still subject to determination.


The estimated flood benefits of the project (excluding road raising and house raising) is estimated to be about $8M in a 100 year flood event, which represents an average annual flood benefit of approximately $650,000, or a net present value of $6.8M. The timing of the proposed works will depend on Council’s overall budgetary commitments and the availability of funds.


1. INTRODUCTION 1.1 OBJECTIVES OF THIS STUDY Bewsher Consulting was commissioned by Hastings Council in October 1999 to develop a floodplain risk management plan for the Camden Haven catchment. The Camden Haven River is located on the mid-coast of New South Wales, about 375 kilometres north of Sydney. Much of the development within the catchment is located close to the coast, at Dunbogan, North Haven, West Haven and Laurieton. Many of the properties in these towns, and others further upstream, are exposed to the risks of flooding. Several flood investigations have previously been undertaken for the Camden Haven area. These include the Camden Haven Flood Study [Willing & Partners, 1989], the Camden Haven Floodplain Management Study [Willing & Partners, 1991] and a review of Council’s floodplain management strategy [Webb McKeown, 1997, 1998]. The objective of the current study is to evaluate various floodplain management measures for Camden Haven and to recommend measures to be included in a floodplain risk management plan. Specific objectives of the study include: ► a review of previous flood investigations; ► quantification of the flood problem in Camden Haven; ► a review of potential floodplain management measures to reduce the risks of

flooding, especially catchment-wide measures such as flood warning, emergency management and planning controls;

► a consultation program that involves the community through the progress of the study; and

► the development of a recommended floodplain risk management plan for the study area outlining the best measures to reduce flood risks, based on consideration of environmental, social, economic and engineering issues.

This study has been overseen by the Camden Haven Estuary Management Committee’s Flood Working Party. 1.2 THE STUDY AREA The study area includes the floodplain of the Camden Haven catchment, including: ► the Camden Haven River, between the ocean and Logans Crossing; ► Stingray Creek; ► Queens Lake; ► Watson Taylors Lake; ► Herons Creek, downstream of the Pacific Highway; and ► Stewarts River, downstream of the Pacific Highway. A map of the study area is shown in Figure 1.1.


1.3 THE GOVERNMENT’S FLOODPLAIN MANAGEMENT PROCESS The prime responsibility for planning and management of flood prone lands in New South Wales rests with local government. The NSW Government provides assistance on state-wide policy issues and technical support. Financial assistance is also provided to undertake flood and floodplain management studies, such as the current study, and for the implementation of works identified in these studies. A Flood Prone Land Policy and a Floodplain Management Manual [NSW Government, 2001] forms the basis of floodplain management in New South Wales. The objectives of the Policy include: ► reducing the impact of flooding and flood liability on existing developed areas by

flood mitigation works and measures, including ongoing emergency management measures, the raising of houses where appropriate, and development controls; and

► reducing the potential for flood losses in new development areas by the application of ecologically sensitive planning and development controls.

The Policy provides some legal protection for Councils and other public authorities and their staff against claims for damages resulting from their issuing advice or granting approvals on floodplains, providing they have acted substantially in accordance with the principles contained in the Floodplain Management Manual. The implementation of the Flood Prone Lands Policy generally culminates in the preparation and implementation of a Floodplain Management Plan, which is the objective of the current study. The steps in the floodplain management process are summarised on Figure 1.2.

FIGURE 1.2

The Floodplain Management Process

Floodplain Management Committee

(Committee to oversee the process & provide local input)

Data Collection

(Data to calibrate flood models & to assess options)

Flood Study

(Determination of existing flood conditions)

Floodplain Management

Study (What can be done

to reduce the impact of flooding)

Floodplain Management

Plan

(The recommended measures)

Implementation of Plan

(Council undertakes recommended

measures)

Periodic Review

Steps previously undertaken

Revie

w

Steps undertaken as part of the current study


1.4 FORMAT OF REPORT Much of the content of this report comes from various working papers that have been prepared during the course of the study. The working papers allowed the Flood Working Party to monitor the project, and to provide direction where required. Working paper titles are listed below: ► Community Consultation; ► Environmental and Planning Issues; ► Flood Damages; ► Emergency Management, Flood Warning and Flood Awareness; ► Flood Prone Land Policy and Development Control Plan; ► Evaluation of Management Strategies. The various working papers have now been consolidated into this report. In doing so, information provided in the original working papers have been amended to include comments received from the Flood Working Party and from the public display, information day and public meeting, which were held in July/August 2001. The report is structured as follows: Chapter 1 – Introduction to the study Chapter 2 – Background information relevant to floodplain management Chapter 3 – Review of previous investigations Chapter 4 – Summary of existing flood behaviour Chapter 5 – Flood damage assessment, including details of a flood damage

database developed for the study Chapter 6 – Consultation activities undertaken during the course of investigations Chapter 7 – A review of existing planning and development controls Chapter 8 – Flood warning and emergency management issues Chapter 9 – General floodplain management considerations Chapter 10 – An assessment of potential floodplain management measures


2. BACKGROUND INFORMATION 2.1 PHYSICAL DESCRIPTION The Camden Haven catchment is located on the mid north coast of New South Wales about 375km north of Sydney. It has a total catchment area of approximately 640 km2, which drains to the ocean via the Camden Haven River. Other major drainage systems include Stewarts River, Stingray Creek and Herons Creek. The upstream parts of the catchment reach a height of RL760m AHD near Comboyne. The upper catchment is steeply sloping and the response to flooding in these areas is relatively rapid. Most development in the catchment is located towards the downstream end of the river, at Dunbogan, North Haven, Laurieton and West Haven. Much of the land in these localities is particularly low-lying, with many properties as low as RL2.0m AHD. Subsequently, many of the properties are exposed to high flood risks. Other development is located further upstream, at Kew and Kendall. Queens Lake and Watson Taylors Lake are major features within the drainage system that have a significant influence on flood behaviour. These lakes have a waterway area of 12km2 and 11km2 respectively. A third, smaller feature is Gogleys Lagoon, which has a surface area of 0.8km2. Flooding can be caused by high ocean levels; high rainfall over the catchment (as was the case for the 1929 flood); or a combination of both (as was the case for the 1963 flood). 2.2 EXISTING LAND USE The study area comprises predominantly environmentally sensitive lands protected within National Parks and Nature Reserves, or by planning instruments (such as SEPP 14 and SEPP 26, discussed later in this report). Urban development comprises a small proportion of the land area of the study area. Those urban areas east of the Pacific Highway are generally adjacent to major waterways such as Queens Lake and Camden Haven Inlet, including the localities of Camden Head, Dunbogan, North Haven, Laurieton and West Haven. The two major urban areas west of the highway include Kew, which is situated on the Pacific Highway itself, and Kendall, which is located on the Camden Haven River. The urban areas comprise predominantly single detached houses on large allotments, with a smaller proportion of medium density housing (predominantly villa homes). There is also a high proportion of tourist-related development (inclusive of caravan parks) and small neighbourhood shopping centres. A series of Crown Reserves are located along the northern foreshores of the Camden Haven Inlet at North Haven. A Plan of Management [Connell Wagner, 1992] provides guidance on the future use, development and management of these


reserves. The main role of the foreshore land is for the provision of outdoor leisure, recreation and environmental protection opportunities. Separate reserves were established in the area by the Department of Lands for the purpose of public recreation, public baths, protection of sand drift, boat ramps, access and parking. Council has responsibility for the day-to-day care, control and management of the land. Another Crown Land reserve is located along the foreshore of Queens Lake. This reserve has an area of about 110ha and is located along a 10km stretch of the southern shoreline of Queens Lake and Stingray Creek. A Queens Lake Foreshore Plan of Management was prepared in 1995 [Pacrim International Pty Ltd, 1995] that outlines a range of management strategies, including: ► formalising a footpath through the reserve from Lakewood to Laurieton; ► upgrading boat launching facilities, picnic, barbecue and playground facilities;

and ► establishing a network of informative signs, maps and brochures covering flora,

fauna, heritage sites and the marine environment. 2.3 EXISTING VEGETATION An analysis of the vegetation within the study area is of importance for the following three main reasons: ► to provide an understanding of the ecological characteristics and value of

vegetation within the study area in order that floodplain management decisions are sympathetic to the conservation values of the vegetation and, where appropriate, take advantage of the opportunities provided by existing vegetation to form open space areas and linkages;

► to ensure that any flood mitigation measures, in particular structural measures, are not fundamentally unacceptable due to their potential impact upon important vegetation areas; and

► to provide a basis for the removal of exotic vegetation or weed species from the river corridor, to improve the river hydraulics (and provide other ecological benefits) which may reduce flood levels or prevent the redirection of the flow path of floodwaters.

With regard to the subject study area, the existence or potential impact of exotic vegetation on the hydraulics of the river is understood not to be a significant issue. Accordingly, the relevance of the vegetation assessment is to ensure that there is a reasonable understanding of the extent of known important vegetation areas to provide a preliminary assessment of potential structural mitigation options and to assist in the determination of land use preferences having regarding to the floodplain management objectives of the study. The significance of the vegetation issue has been taken into consideration in the review of potential flood mitigation measures reported in Section 10.


Large expanses of areas containing important vegetation communities within the study area are conserved by one of the following mechanisms: ► National Parks; ► State Forests; ► Wetlands identified under State Environmental Planning Policy No. 14; ► Littoral rainforest identified under SEPP No. 26; and ► Land owned or under the care, control and management of Council where

vegetation preservation is integrated within Plans of Management (eg. North Haven Foreshores Reserve Plan of Management).

The above areas have been mapped by Council and are identified on Council’s GIS system. In some cases, the above mechanisms may overlap, eg. Council Reserve land may also be identified as affected by SEPP 14 or SEPP 26. A Native Vegetation Management Plan was also prepared for Hastings Council in 1999 [Susanne Cooper & Associates, 1999]. The study included an assessment of vegetation condition, levels of protection provided under existing legislation, conservation priorities and management recommendations. Recommendations from the Plan were reported in the Estuary Management Study [Patterson Britton & Partners, 2000]. These recommendations are also relevant to the current Floodplain Risk Management Study, and include: ► retain partially vegetated edge to Queens Lake, whilst seeking to re-establish

vegetation along the cleared parts of the lake edge; ► retain the diversity, condition and intact nature of the vegetation mosaics in the

National Park north of Queens Lake; ► secure long term protection for the majority of land coastward from Queens Lake

south of Bonny Hills; ► support DLWC in any negotiations with rural landholders around Herons Creek to

enter into property agreements to retain the dense and intact riparian vegetation along Herons Creek;

► encourage conservation of “Priority 1” vegetation through voluntary conservation agreements throughout the rural hinterland;

► retain existing riparian vegetation throughout the rural hinterland; ► consider amending the Tree Preservation Order to a Vegetation Preservation

Order to give it wider applicability; and ► develop a GIS layer for Council showing Priority 1 and 2 conservation areas to

flag those areas where development proposals should incorporate vegetation retention and management considerations.

As the majority of the above mechanisms identify vegetation communities that exist in low lying areas, significant portions of the floodplain are consequently constrained from the likelihood of urban development. In these circumstances, the potential to increase development and population within these affected parts of the floodplain are minimal, and therefore the consequential increased risk to property and persons as a result of the flood hazard is controlled by default. The uses put to these lands in


conjunction with the objective of preserving the vegetation communities would normally be compatible with the flood hazard. Similar to the constraint on urban development, the identified expanses of important vegetation communities place limitations on potential flood mitigation measures, which are discussed in Section 10. 2.4 ACID SULPHATE SOILS Acid sulphate soils are sediments deposited under estuarine conditions (ie. close to sea level) and which contain the sulphidic mineral, pyrite. Acid sulphate soils are found underlying many coastal floodplains and coastal wetlands, and as bottom sediments in coastal estuaries. While acid sulphate soils are not disturbed or drained, these materials are relatively harmless and are termed ‘potential acid sulphate soils’. However, if these sediments are exposed to air, the pyrite is oxidised, and sulphuric acid is generated. When the rate of acid production exceeds the neutralising capacity of the parent material, the actual acid sulphate soils are formed. As a result, soil pH may fall to below 4. The relatively specific conditions under which acid sulphate soils are formed usually limit their occurrence to low lying parts of coastal floodplains, rivers and creeks. Due to flooding and stormwater erosion, these sulphidic sediments may continue to be redistributed through the sands and sediments of the estuarine floodplain region. Sulphidic sediment may be found at any depth in suitable coastal sediments, usually beneath the water table. Hastings Council has mapped potential acid sulphate soils upon the GIS system within five classes of land, depending upon the severity of potential to create actual acid sulphate soils. Due to the nature of acid sulphate soils, the majority of the study area has been mapped as containing potential acid sulphate soils. The following activities are those which may risk the exposing of acid sulphate soils: ► excavation or disturbance of acid sulphate soils (eg. construction of roads,

foundations, drainage works, laser levelling, land forming works, flood mitigation works, dams and aquaculture ponds, sand or gravel extraction or dredging);

► lowering the water table (eg. new drainage works or deepening of existing drains, use of groundwater, dewatering of dams, wetlands or quarries, or dredging works lowering the bed of a river);

► use of acid sulphate soil (eg. aquaculture pond walls, dams, flood mitigation works, imported fill material and reclamation or foreshore works); and

► physical habitat modification for mosquito control (eg. drainage and selective ditching to remove water or allow predatory fish access to tidal pools).

The implications of acid sulphate soils for the Camden Haven Floodplain Risk Management Plan are twofold: ► the existence of acid sulphate soils, which cover the majority of the floodplain,

provides a constraint to more intensive urban use of the floodplain; and


► any flood mitigation works may have potential to create actual acid sulphate soils. The constraints to urban development due to acid sulphate soils, are not necessarily insurmountable, and may be addressed with appropriate management measures. Notwithstanding, the existence of potential acid sulphate soils creates another layer of constraint to urban development within the floodplain. The greatest implication of acid sulphate soils for this floodplain risk management plan, is the implication for any structural flood mitigation measure. A report on acid sulphate soils priority management areas on the Lower Hastings and Camden Haven floodplains was prepared in 1999 for the DLWC. This report identified potential acid sulphate soils related problems arising due to past flood mitigation works. These problems arise due to the construction of levees, excessive drainage of back swamps and the installation of flood-gated drains. The consequences are significant impacts upon natural ecosystems and associated water quality impacts upon human activities such as recreation and building. Two important sites of exposed acid sulphate soils have been identified in the Camden Haven catchment. These are located at: ► Rossglen, immediately downstream of the Pacific Highway on the north side of

the river; and ► Stewarts River, between the Pacific Highway and Watson Taylors Lake. The Rossglen site was cleared and drained for agricultural purposes many years ago. The current drainage system comprises a levee and four artificial drains with tidal floodgates that discharge to the Camden Haven River at low tide. The site is currently zoned rural and is used predominantly for grazing. Previous investigations [SMEC, 1998] estimate that more than 80% of the Rossglen area is underlain by potential and actual acid sulphate soils. It has been estimated that there is an average of 1m depth of actual acid sulphate soils overlying at least 2m of potential acid sulphate soil across a 750ha area of Rossglen. A number of management options have been proposed for the Rossglen area [SMEC, 1998] to control the quantity and quality of discharge from the drains, including re-engineering the drainage system, liming and mulching of scalds and spoil banks, and controlled partial floodgate opening. The site was identified as an Acid Sulphate Soil Priority Management Area [DLWC, 1999]. An Acid Sulphate Soil Land Management Plan was recently prepared, which is being coordinated by the Rossglen Acid Sulphate Soils Land Management Plan Working Group. This Group comprises council officers, landowners and State Government representatives. Parts of the floodplain on the lower Stewarts River, between Watson Taylors Lake and the highway, were previously cleared and drained for agricultural purposes. The acid sulphate soils problem in the Stewarts River was first identified in March 1998. The Wharf Road Landcare Group reported that over the course of a number of days the river had “gone brown, then white, and then grey-black” [Patterson Britton, 2000]. Fish were reported to have died and the river smelt of hydrogen sulphide. This has been attributed to acid runoff from the low-lying areas that were able to enter the river due to unusually low tides that occurred at the time.


The Stewarts River site is located within the Taree Council area. The site is currently used for grazing, and occupies an area of approximately 45ha. The site is also identified as an Acid Sulphate Soil Priority Management Area [DLWC, 1999]. The Stewarts River Landcare Group has recently carried out fencing and revegetation of a large scald on the southern side of the river and the construction of sandbag weirs along the drain is proposed. Liming and drain reconstruction has also been carried out on another drain. The potential impacts of acid sulphate soils must be carefully taken into consideration in the assessment of any structural flood mitigation measures. Programs to address past problems (described above) associated with flood mitigation works are being dealt with independent to this study. 2.5 HERITAGE 2.5.1 Aboriginal Heritage The general study area was formerly occupied by the Ngamba tribe of Aborigines whose territory extended along the coast from Taree to the Hastings Valley. Nineteen Aboriginal sites have been recorded to date within a coastal strip from the mouth of the Camden Haven River south to Diamond Head [Collins, 1998]. The majority of these sites are located in the Dunbogan area, between the river and the coast. The known sites are dominated by shell middens, which have been consistently found along the banks of the river and on hind dunes that provided well-drained camping sites adjacent to swamps. Other sites are also presumed to have been present around Queens Lake and Watson Taylors Lake, although no surveys have been undertaken in these areas [Collins, 1998]. Parts of vacant Crown Lands between Queens Lake and Grants Beach, and stretching between North Haven and Bonny Hills are subject to Aboriginal Land Claims lodged with the Taree office of the Department of Land and Water Conservation. 2.5.2 European Heritage In 1821 a penal settlement was established in Port Macquarie, as a place of secondary punishment to receive convicts who had transgressed the law for a second time after transportation to New South Wales. White settlement in the Camden Haven catchment commenced shortly afterwards, with the establishment of a “limeburning” industry. Oyster shells were burnt to produce lime for mortar, which was needed for construction of buildings in Port Macquarie. By the late 1880’s, settlers were arriving by steamer to settle on the rich alluvial flats in the Camden Haven catchment. The primary agricultural activity was corn growing and a number of dairy farms were later established. By the 1890’s the timber industry began to expand and a number of sawmills were constructed. An important timber trade to Sydney was established, with reliance on the river for transportation. Ports at Kendall and Johns River, which are located near the navigable limits of the


Camden Haven River and Stewarts River, were established to serve the timber industry. The timber ships often encountered difficulties at the entrance to the Camden Haven Inlet, as it was often unstable and treacherous to navigate. In 1912 the northern and southern breakwaters were constructed which improved the navigability of the entrance. Between 1911 and 1915, the North Coast Railway was constructed through to Johns River and Kendall. This reinforced the positions of these towns as the centre of commerce within the catchment. However, river transportation persisted through until the late 1950’s, when road transport became the major transport mode. Since the 1970’s the recreational and aesthetic values of the Camden Haven estuary have been recognised and urbanisation of the lower catchment has increased. Tourism, boating, fishing and other water-related activities have become increasingly important. 2.5.3 Significance for the Current Study The issue of heritage is of significance in regard to forming an understanding of the social and cultural context of the floodplain and to ensure that any flood mitigation measures do not impact upon the heritage of the study area. The Hastings LEP and North Coast REP contain listings of heritage items. These instruments also contain detailed provisions to control development that may impact upon these heritage items. Heritage items of State or Regional significance within the study area include: ► Kendall School of Arts building (19 Comboyne Street); ► Kew Police Station (formerly the Kew Court House); and ► Laurieton School of Arts building (58 Bold Street). Other items of heritage significance include: Kendall ► Kendall railway station buildings (Railway Street) ► Kendall railway bridge (over the Camden Haven River) ► ANZAC War Memorial (Comboyne and Anzac Streets) ► All Saints Anglican Church (Comboyne Street) ► Roman Catholic Church building (Laurel Street) ► Uniting Church building (Laurel Street) ► Cemetery (Kendall Forest Road) ► School building (Comboyne and Logans Crossing Road) ► Dwellings (34 Comboyne St, 9 Laurel St, 23 Railway St)


Herons Creek ► Saint Mary The Virgin Church Laurieton ► ANZAC War Memorial (Bold & Castle St) ► Holy Trinity Church (Bold St) ► Former Post Office and single dwelling (5 Laurie St) ► Cemetery North Haven ► Training wall (Camden Haven River entrance) ► Dwellings (623 Ocean Drive, 639 Ocean Drive) Camden Head ► Training wall (Camden Haven River entrance) ► Pilot station (via Camden Head Road) ► Graves (Camden Head Road) The historic significance of the floodplain and the particular heritage items which it contains will be taken into consideration in the formulation of eventual land use and planning controls and the assessment of the impact of potential structural flood mitigation measures. 2.6 POPULATION CHARACTERISTICS An understanding of population characteristics and development trends within the study area is an important consideration of floodplain management studies. It helps to provide an understanding of the values that the community has in regard to the utilisation of the floodplain, as opposed to sterilising its use to minimise the risks of flooding. ABS census data was collected for the collector areas that most closely matched the study area (ie land below the PMF flood extent). As the collector district areas for the census data extended beyond that of the study area, the census data represents a wider total population. There are approximately 1,100 potentially flood affected dwellings within the study area, which equates to approximately 2,530 persons, compared to a population of 7,250 persons covered by the census data. Accordingly, an analysis of this Census data cannot be used to conclude absolute numbers, but does provide an appropriate analysis of demographic trends. The ABS census data was collated for the 1986, 1991 and 1996 Censuses. These results are shown in Table 2.1, with salient points summarised below: ► There was approximately a 50% increase in the population between 1986 and

1996, representing an annual compound rate of growth of 6.1%. In comparison,


the annual compound rate of growth of the Hastings LGA during the same period was 3.7% and for NSW overall, was 1.2%.

► The median age of the study area in 1996 was 51. This compares with 42 for the

Hastings LGA overall, and 34 for NSW. The higher proportion of older persons in the study area has implications for various floodplain management measures, as follows: - Evacuation difficulties for frail and aged persons; - Access difficulties associated with the raising of floor levels of dwellings and

public places such as halls and shops; - Long-term financial impacts to individual households associated with flood

damage to property, particularly where there may be a limited long-term income potential together with the lack of domestic flood insurance in Australia.

► Income levels are also relatively low for the study area, with the median

household income level being $19,400, which compares with $34,000 for NSW. It should be noted, however, that the area contains a high proportion of retirees, who may be relatively asset rich.

► The majority of the population of the study area (89%) are Australian born and

effectively, there are no poor English speaking persons. Consequently, public flood awareness programs do not need to be targeted to particular ethnic groups, as is the case for other areas of NSW.

► The participation rate in the labour force is extremely low, at 35% (reflective of

the high proportion of retirees), which contrasts with a 60% participation rate for NSW as a whole.

► The occupancy ratio of dwellings is 2.30 persons, which is marginally below the

NSW average of 2.69 persons. This slightly lower occupancy rate is reflective of the high proportion of retired couples or single persons with no children, within the study area.

► The majority of households live in dwellings which they own or are purchasing

(73%), while only 19% of households live in rented dwellings. This compares with 65% and 28% respectively for NSW overall.

► The average number of vehicles per dwelling is 1, which is the same for NSW as

a total. ► The types of dwellings in the study area comprise 72% separate houses and

28% medium density dwellings.

Table 2.1 Analysis of Census Information : 1986 to 1996

Table 2.1 (cont) Analysis of Census Information : 1986 to 1996


2.7 Development Trends and Strategic Planning Directions In June 2000, Council published the Draft Hastings Urban Growth Strategy [HUGS, 1999]. The general recommendations of this Strategy (page 3 of the Executive Summary) are as follows:

“ • support ongoing population growth; • facilitate expansion of tertiary education and employment

opportunities (although this is achieved in the detail planning at later stages);

• not increase housing costs (ie. through high development costs); • explore opportunities for increased housing densities (eg. with high

proportions for more compact housing); • attempt to facilitate accessibility to facilities without dependence on

private motor vehicles. ” Other more specific recommendations include the need to address environmental hazards (including flooding and poor drainage) as part of any detailed environmental study preceding urban development. Major urban expansion within the study area is not envisaged by the Strategy, to accommodate the expected population growth of the Hastings LGA. The report concludes that there is sufficient residential zoned land in the Camden Haven locality to accommodate current growth rates in this area. Notwithstanding, some minor demand for additional residential land might proceed subsequent to the provision of a sewerage treatment plant for Kendall. In 1998, Council published a separate Urban Strategy for the Kew and Kendall region. This Strategy indicated that in the preceding 10 years, growth varied between nil and 1.5% per annum, but this low rate of growth may have been artificially suppressed as a result of Council’s policy to restrict residential subdivision in unsewered village areas. The 1998 Strategy was in response to a commitment to provide a reticulated sewerage scheme for the region, which was anticipated to result in development and population growth. This Strategy identifies a number of locations for the potential expansions of Kew and Kendall. These areas are predominantly on high land outside of the floodplain with the exception of a small portion of a Priority 2 area located immediately to the south of Kendall. This area is located partially between the 100 year flood extent and the PMF. However, evacuation during potential floods would not appear a difficulty, subject to appropriate local road design, and accordingly the issue of flooding subject to other general considerations would not appear to be an absolute constraint. During 1992, Council published a discussion paper regarding the potential growth of the North Haven Neighbourhood Shopping Precinct. This discussion paper recognises the potential to expand the shopping precinct to cater for both population growth and tourist development, but notes the constraints imposed due to the flooding hazard. This discussion paper led to the adoption of DCP 24 – North Haven Shopping Precinct as discussed later at Section 7.6 of this report. Generally, the development controls recognise the tourist opportunities of the precinct, the need to cater for the growing retail needs of the population and the desire to create an aesthetically pleasing shopping precinct when applying flood related development


controls (principally minimum floor levels). The report generally notes that while habitable floor levels are required to be located 800mm above the 100 year flood, commercial and retail floor space is permitted at the 20 year flood level, provided that 20% of the floor area is located 800mm above the 100 year flood level to provide for storage during times of flood. Similar flood related controls are also stipulated in regard to alterations and extensions to existing buildings.


3. REVIEW OF PREVIOUS STUDIES 3.1 CAMDEN HAVEN FLOODPLAIN MANAGEMENT STUDY

[Willing & Partners, December 1991] The Camden Haven Floodplain Management Study was undertaken by Willing & Partners Consulting Engineers for Hastings Council in December 1991. The report investigated a number of structural and non-structural measures for Camden Haven. Measures presented in the floodplain management study are described below. These measures, and others, are further reviewed in Section 10. Structural Measures (Measures that modify the flood) Structural measures considered in the 1991 study are summarised in Table 3.1. These measures mainly involve a number of levees and development proposals that require filling of land to reduce its susceptibility to flooding. Ten structural measures, listed in Table 3.1, were analysed singularly and in various combinations. Measures A,B,C,D were targeted at reducing existing flood problems by the construction of levee banks or works to seal the northern training wall. It was recognised that there would be internal drainage problems associated with all levee options and that these measures were unlikely to be favoured by the community. Only Measure B (sealing the northern training wall) was recommended. Measures E,F,G,H,I were measures associated with future development. These were considered in various combinations, four of which (known as Options 12, 13, 14, & 15) were considered in more detail. Option 15, which incorporates measures E,F,G,H, I(b) was considered preferable to the other options. However, it was noted that all options resulted in an increase in flood damages to existing development. It was therefore recommended that developers should be required to demonstrate that the benefits of their development to the community outweigh the community costs. One of the main areas to suffer, should Option 15 be implemented, was noted to be the area around Lakewood Village, where the 100 year flood level was estimated to increase by up to 0.18m. Several low lying houses were identified as being potentially affected by this increase. A low level, landscaped levee was therefore proposed to provide protection to these properties. A high level road to the north of North Haven (Measure J) was also considered, although no specific recommendation on this measure appears to have been made. A subsequent investigation recommended against the proposal. Other structural measures that were initially considered, but dismissed from further consideration in the floodplain management study, include: ► dredging of Stingray Creek; ► the removal of the rock bar, known as the Klondyke, in the Camden Haven River

near Gogleys Lagoon; and ► construction of a channel between Queens Lake and the Ocean.


Table 3.1 Structural Measures Considered in the 1991 Study

Measure Description Details provided in the 1991 Study

A Ring Levee around North Haven

A ring levee, 3.3km long and 2.2m high, to protect 288 residences and 27 commercial properties. Flood levels increase by up to 0.09m and velocities up to 0.2m/s in the 100 year flood. Requires local drainage diversions, pumps and excavation of storage area. Estimated cost $5.3M*.

B Seal North Training Wall

Sealing of the training wall estimated to provide protection to 49 properties from backwater flooding. Also requires flood-gated pipes and other local drainage improvements. This option has been subject to further investigations. Estimated cost $0.3M*.

C Ring Levee around Dunbogan (4 variations)

A ring levee up to 4.2km long around Dunbogan could protect up to 164 dwellings and 8 commercial premises. Flood levels were estimated to increase by up to 0.17m and velocities up to 0.2m/s in the 100 year flood. Storage excavation, pumping & drainage works would be necessary. Estimated cost $5.0M*. Three smaller variations of this option were considered that aimed to provide flood free access to the bridge to Laurieton.

D Levee around part of Laurieton

The proposed 1.7km long levee, extending between Lake St and Ocean Drive, would protect 106 dwellings and 9 commercial premises. An excavated storage area and pumps would be required behind the levee for internal drainage. Local drainage works could reduce these requirements. Maximum flood level increase of 0.05m and velocity increase of 0.12m/s for the 100 year flood when combined with other Laurieton options. Estimated cost $2.0M*.

E Fill & develop south of Laurieton

A local measure that could permit development of this parcel of land currently zoned 1(a2) – rural floodprone. All work would be carried out and funded by the developer.

F Fill & develop further south of Laurieton Similar to Measure E.

G Dunbogan Canal Estate

This was included in the list of measures considered in the floodplain management study, as it was a private development proposal under consideration at that time. This development has since been rejected and is therefore no longer applicable.

H Fill & Develop small area in Laurieton

This comprises a small area in Laurieton that had already largely been filled for development. All costs would be borne by the developer.

I Fill North Haven to Queens Lake & Develop

This measure involves filling all or part of the area between North Haven and Queens Lake. Six variations of filling were investigated. Maximum filling would result in flood level increases of 0.18m in the 100 year flood in Queens Lake. Only partial filling of this area, ie Measure I(b), was recommended. All costs would be borne by future development of the area.

J High level road between North Haven & Laurieton

This measure comprises a high level road along the rear of properties in Eames Av, North Haven and raising of the existing causeway leading from the bridge over Stingray Creek to Laurieton.

* Costs and properties numbers based on data supplied in the 1991 study ($1991)


Non-Structural Measures (that modify the property, or people’s response) Non-structural measures were seen to comprise the main component of the preferred floodplain management strategy for the Camden Haven area. Non-structural measures that were considered appropriate are summarised in Table 3.2. Table 3.2 Non-Structural Measures Considered in the 1991 Study

Description Details provided in the 1991 Study

Flood Warning and Evacuation Planning

A flood warning system, providing up to 6 hours warning time, was seen as beneficial in reducing potential flood damages. It was noted that prediction of oceanographic effects would be an important component of the system and that coordination with the Bureau of Meteorology was essential. An evacuation plan was also recommended in association with the flood warning system.

House Raising

A house raising scheme was recommended for timber and fibro cottages and permanent caravans, subject to the availability of government funding. The scheme was estimated to cost $8M* if all suitable houses were raised above the 100 year flood. No details of properties to be included in the scheme were provided. It was also noted that it might be preferable to only raise the worst affected dwellings.

Zoning and Development Control Measures

It was recommended that the current zoning in both urban and rural areas be reviewed. It was also recommended that habitable floor levels have a freeboard of 800mm above the 100 year flood in the lower study area, reducing to 500mm freeboard upstream of the Pacific Highway. The increased freeboard allowance was to cater for possible greenhouse effects.

Public Education and Information Very little information was provided on flood awareness activities. It was noted that Section 149 certificates provided a means to make people aware of the flood danger.

* Costs based on data supplied in the 1991 study ($1991) The Recommended Strategy The floodplain management study recommended the following strategy: ► a review of current zoning controls for flood liable land and a freeboard allowance

for new buildings of 800mm above the 100 year flood in the lower study area, reducing to 500mm upstream of the Pacific Highway;

► investigation of a house raising scheme; ► implementation of a flood warning system; ► structural works to seal the northern training wall (Measure B); and ► provision of a low, landscaped levee at Lakewood Village to protect low-lying

houses. Whilst no development options were specifically recommended, it was noted that should future development of flood liable land occur, it was preferable for this to be in accordance with Option 15, with developers required to demonstrate that the benefits of the development to the community outweigh the costs.


3.2 COUNCIL’S FLOODPLAIN MANAGEMENT STRATEGY Council formally adopted a floodplain management strategy for Camden Haven on 23rd March 1992, based on the findings of the floodplain management study. The adopted strategy was: i) zoning and development control measures being implemented to ensure that

appropriate zoning applies for flood prone areas and that 800mm freeboard at the ocean, falling to 500mm at the Pacific Highway, be provided for new development;

ii) implementation of a voluntary house raising scheme subject to the availability of government subsidy;

iii) action being taken to have a comprehensive flood warning system implemented for the area;

iv) construction of an impermeable flood gated levee to protect the eastern part of North Haven from river flooding;

v) construction of a low landscaped levee at Lakewood Village to protect low lying houses;

vi) new development on land which is now flood liable to be restricted to that shown in Option 15 of the study with developers being required to demonstrate that the benefits of the development to the community outweighs the costs.

3.3 NORTH HAVEN DRAINAGE STUDY [Willing & Partners, September 1991] The report presents the results of investigations of measures to upgrade the trunk drainage system of the area of North Haven, between Ocean Drive and Grants Beach. The trunk drainage system in this area consists of an open drain between Bayside Avenue and David Campbell Street, a box culvert under the Beachfront Caravan Park, and an open drain from The Parade to a ponding area beside the northern training wall. Problems relate to inadequate drainage capacity, backwater flooding from the Camden Haven River and strong odour problems. Various flood mitigation measures were investigated. The most effective measure in reducing flooding problems included: ► regrading the channel downstream of The Parade to eliminate an adverse

channel slope; ► widening the channel downstream of The Parade, over a distance of about 100m,

to provide an invert width of 10m; ► installation of an additional 1.2m x 1.8m box culvert beside the existing culvert; ► improving the transition between the upstream channel and the existing culvert. The above works were estimated to cost $620,000 ($1991), with a benefit-cost ratio of 0.08. The works were not recommended due to the low benefit-cost ratio, with house raising suggested as a possible alternative.


The report also notes that flooding is also influenced by backwater from the river through the northern training wall. It was noted that flooding could be prevented from this source by the construction of an impermeable barrier at or upstream of the training wall, with a flood gated opening for the drain. 3.4 NORTH HAVEN DRAINAGE INVESTIGATION - BEACHFRONT CARAVAN

PARK [Willing & Partners, Draft Report V2, September 1997] This report further investigates flooding in the vicinity of the Beachfront Caravan Park. The report notes that trunk drainage improvement works have been undertaken by developers and Council since the 1991 investigations in this area. Whilst this will have improved the capacity of the drain, it was also noted that flows in the drain are likely to have increased as a result of further development. The study examines a range of measures to alleviate flooding in both the caravan park and neighbouring residential area. Recommended measures include: ► widening of the channel downstream of The Parade; and ► provision of a grassed open channel along the northern and eastern boundary of

the caravan park and a box culvert under The Parade. The cost of these measures was estimated at $290,000 ($1997). 3.5 REVIEW OF CAMDEN HAVEN FPM STRATEGY - STAGE 1

[Webb McKeown & Associates, November 1997] This report presents a review of Council’s floodplain management strategy for Camden Haven, to determine: ► whether it is in accordance with the Floodplain Development Manual; ► which elements of the strategy are no longer feasible; and ► which elements of the strategy have already been undertaken. A status report on the various elements suggested in the 1991 floodplain management study, and Council’s adopted floodplain management strategy, is provided. It is noted that a number of elements of the adopted strategy (ie Option 15) are no longer feasible, or extremely unlikely to proceed, including: ► the Dunbogan Canal Estate (Measure G); ► proposed filling of the area south of Laurieton (Measures E & F); and ► filling between North Haven and Queens Lake (Measure I). The report recommends further floodplain management investigations and the preparation of a floodplain management plan.


3.6 REVIEW OF CAMDEN HAVEN FPM STRATEGY - STAGE 2 [Webb McKeown & Associates, July 1998] The report provides a review of the present floodplain management strategy for Camden Haven and presents proposals to update the strategy, in accordance with the State Government’s flood policy and other changes in the philosophy of floodplain management. The report recommended the preparation of: ► a supplementary floodplain management study, to review and address any

omissions from the 1991 floodplain management study; and ► a floodplain management plan, to outline recommended works and planning

issues for Camden Haven. 3.7 CAMDEN HAVEN ESTUARY MANAGEMENT STUDY

[Patterson Britton & Partners, 2000] A draft estuary management study was recently completed for Camden Haven. The estuary management study identifies the essential features of the current uses of the Camden Haven estuary, and determines the overall objectives required for the management of the estuary. Whilst the current floodplain risk management study is involved with managing the risk of mainstream flooding within the Camden Haven catchment, the Estuary Management Study addresses other issues for the waterways and lakes, including such matters as: ► the general health of the estuary and other water quality issues; ► tidal processes, such as tidal ranges and tidal flushing; ► erosion and siltation issues; ► important elements within the estuary, for example sea grasses; and ► the various uses that are made of the estuary, such as navigation, fishing, oyster

leases, etc. Recommendations and other findings from the Estuary Management Study that could have an impact on flood behaviour, or the likely recommendation from the current study, includes: ► dredging of the channel through the Stingray Creek delta at Queens Lake to

improve navigation; ► dredging of the channel through the Camden Haven River fluvial delta at Watson

Taylors Lake; ► enforcement of erosion and sediment controls for development and activities

which have the potential to impact on the estuary; ► recognition that seagrasses in the Camden Haven estuary form one of the richest

biological resources of their type in New South Wales, with the most important areas located in Queens Lake, Gogleys Lagoon and the eastern half of Watson Taylors Lake.


4. EXISTING FLOOD BEHAVIOUR 4.1 HISTORY OF FLOODING There is a history of flooding in the Camden Haven catchment. Significant floods are reported to have occurred in: ► February 1929; ► February 1956; ► April 1963; ► March 1974; ► May 1980; and ► July 1999. The largest recorded flood in the lower Camden Haven occurred in April 1963. This flood was the result of heavy rainfall between the 26th and 29th April 1963, combined with high ocean conditions. Recorded flood heights were close to the estimated 100 year flood level throughout much of North Haven, Laurieton and Dunbogan. The flood is estimated to have been less severe further upstream. The largest recorded flood in the upper catchment, between the highway and Kendall, occurred in February 1929. There is also evidence that this flood was similar to the estimated 100 year flood level in the upper catchment. As high ocean conditions are not likely to influence flooding in the upstream river, the 1929 flood is thought to have been due largely to heavy rainfall only. More recent floods in the Camden Haven catchment have been less severe. 4.2 DESCRIPTION OF THE FLOOD PROBLEM Information on flood behaviour is available in the Camden Haven Flood Study Report [Willing & Partners, 1989]. The report provides estimated flood levels for the 20 year, 50 year, 100 year and probable maximum floods. These levels are expressed as heights above Australian Height Datum. No levels are currently available for Herons Creek or Stewarts River. It is important when comparing estimated flood levels with flood gauges or other features in the catchment, that all comparisons are made using the same datum. Most flood gauges have been installed to Australian Height Datum; however some are set to other datums. The gauge at Logans Crossing, for instance, is reported to be set to a local Water Resources Datum. Readings from this gauge will need to have a value of 2.04m added to the reading to convert the level to Australian Height Datum. All tide charts and tidal levels are normally quoted as a height above Indian Spring Low Water Level. These levels are approximately 0.9m higher than Australian Height Datum. Flood velocities are also provided in the 1989 flood study. Values on the floodplain downstream of Queens Lake and Watson Taylors Lake are typically in the range of


0.1 to 0.3m/s for the 100 year flood. The quoted velocities are peak values, averaged over the floodplain where they occur. These values are relatively low, due to the attenuating effects of both Lakes and the influence of elevated ocean conditions in the lower estuary. However, under different flood scenarios, particularly with lower ocean conditions, appreciably higher flood velocities can be expected. Higher flood velocities are also experienced upstream of both lakes. The 1989 study did not consider the cumulative impacts associated with future development. 4.3 SUMMARY OF PROPERTY INUNDATION A flood damages database of potentially flood affected buildings has been prepared for the study area. The database, which is discussed in more detail in Section 5, provides details of those properties likely to be inundated in different sized floods. The number of residential and commercial/industrial properties that are potentially affected by flooding in Camden Haven is shown in Tables 4.1 and 4.2. A more detailed description of those residential homes that are potentially subject to flooding is also shown in Table 4.3. Results from these Tables show that: ► In the probable maximum flood it is estimated that:

- 1,253 residential properties (containing a house) would be flooded - 1,106 residential homes would be flooded above floor level - 75 commercial or industrial properties (containing buildings) would be flooded - 70 commercial and industrial buildings would be flooded above floor level;

► In the 100 year flood it is estimated that: - 891 residential properties (containing a house) would be flooded - 653 residential homes would be flooded above floor level - 57 commercial or industrial properties (containing buildings) would be flooded - 46 commercial and industrial buildings would be flooded above floor level;

► There are many more residential properties affected by flooding than commercial or industrial properties;

► There is not an unduly large increase in the number of properties and buildings that are flooded in the probable maximum flood compared with those flooded in the 100 year flood;

► The number of homes that would be flooded in the 100 year flood throughout the study area (excluding motel units, mobile homes and caravans) is as follows: - North Haven (380) - Dunbogan (156) - Laurieton (61) - Kendall & Rural surrounds (49) - West Haven & Lakewood Village (7);

► Eight caravan parks are included in the list of potentially flood liable commercial properties, namely: - Dunbogan Caravan Park - Diamond Waters Caravan Park


- The Haven Caravan Park - Laurieton Gardens Caravan Park - Christmas Cove Caravan Park - Brigadoon Caravan Park - Jacaranda Caravan Park - North Haven Beachfront Caravan Park.

Table 4.1 Residential Property Affected by Flooding

20 yr Flood 50 yr Flood 100 yr Flood PMF Location

Property Homes Property Homes Property Homes Property Homes

Dunbogan 163 147 164 152 166 156 172 170

Laurieton 73 48 92 59 101 61 157 148

North Haven 467 193 495 273 524 380 586 522

West Haven & Lakewood 6 0 7 6 44 7 235 174

Kendall & Rural areas 25 18 52 25 56 49 103 92

Herons Ck & Misc.1 - - - - - - - -

TOTAL 734 406 810 515 891 653 1,253 1,106 1. No flood level information available Table 4.2 Commercial, Industrial & Public Sector Properties Affected by Flooding

20 yr Flood 50 yr Flood 100 yr Flood PMF Location

Property Buildings Property Buildings Property Buildings Property Buildings

Dunbogan 8 4 8 6 9 7 9 9

Laurieton 4 1 5 4 5 4 12 9

North Haven 30 17 31 22 32 28 32 32



Herons Ck & Misc. 1 - - - - - - - -

TOTAL 47 27 51 37 57 46 75 70 1. No flood level information available 2. Buildings with multiple units (eg motels and caravan parks) counted as a single building only.


Table 4.3 Location of Residential Homes Affected by Flooding

Number of Houses Inundated Location 0.5m below

20 Year 20 Year 50 Year 100 Year PMF

Dunbogan Bay St 5 13 13 13 13 Beach St 0 0 0 3 3 Bell St 27 38 38 38 39 Camden Head Rd 17 22 22 22 22 Diamond Head Rd 0 0 0 0 7 Longworth Rd 22 31 32 32 36 River St 3 4 4 4 4 Scarborough Way 0 0 0 0 1 The Boulevarde 29 39 43 44 45 103 147 152 156 170North Haven Adeline St 0 6 6 6 6 Alfred St 12 50 69 71 76 Alma St 4 25 27 27 30 Bridge St 1 3 4 4 4 Coral St 0 1 2 22 24 David-Campbell St 0 0 1 3 20 Eames Ave 14 32 34 35 37 Edith St 0 2 8 15 32 Glen Cl 0 0 0 0 23 Hillman St 0 0 2 3 4 Jacaranda St 0 0 1 1 3 Leighton Cl 0 3 7 14 25 Lepemi Pl 0 11 14 14 16 Murson Cres 0 0 0 24 24 Ocean Dr 8 40 57 66 72 Ocean St 0 0 0 0 21 Pioneer St 6 16 16 16 19 River St 0 0 7 7 7 Riverview Pl 0 0 0 0 6 The Parade 0 0 10 43 62 Vine St 0 4 6 7 7 Wall St 0 0 0 0 2 Woodford Rd 0 0 2 2 2 45 193 273 380 522Laurieton Arnott St 1 3 3 4 7 Castle St 0 3 6 6 12 George St 0 0 0 0 11 Haven Circuit 8 20 21 21 28 Lake St 0 0 0 1 24 Lane St 1 4 4 4 11 Laurie St 0 0 1 1 1 Lord St 0 1 1 1 1 Mclennan St 0 0 0 0 9 Ocean Dr 4 12 18 18 33 Reid St 0 0 0 0 1 Short St 3 5 5 5 5 Wharf St 0 0 0 0 5 17 48 59 61 148


Table 4.3 (cont.) Location of Residential Homes Affected by Flooding

Number of Houses Inundated Location 0.5m below

20 Year 20 Year 50 Year 100 Year PMF

West Haven Blue Gum Pl 0 0 0 0 4Brotherglen Dr 0 0 0 0 1Mountain View Rd 0 0 0 0 6Ocean Dr 0 0 0 0 23Pelican Court 0 0 6 6 12St Albans Way 0 0 0 0 2The Gateway 0 0 0 0 1The Silhouette 0 0 0 0 1 0 0 6 6 50Lakewood Village Botanic Dr 0 0 0 0 12Cook Cl 0 0 0 0 14Honeysuckle Ave 0 0 0 0 20Mahogany Cl 0 0 0 1 7Mangrove Cl 0 0 0 0 6Phillip Cl 0 0 0 0 11Sirius Dr 0 0 0 0 43Tern Cl 0 0 0 0 11 0 0 0 1 124Kendall Araluen St 0 0 1 2 3Berryman Rd 0 0 0 0 2Fagans Cres 0 0 0 1 1Foxes Creek Rd 0 0 0 0 3Graham St 0 0 0 0 1Kendall Rd 0 0 0 0 4Kingsford Rd 0 0 0 0 1Logans Crossing Rd 0 0 0 0 4Loganvale Pl 0 0 0 3 3Lorne Rd 1 1 1 1 1Old Bridge Rd 2 2 2 2 2Railway St 0 0 1 3 11River Oaks Dr 0 0 0 0 3River St 9 10 10 10 10 12 13 15 22 49Kew Ivers Rd 1 1 1 1 1Ocean Dr 0 0 0 0 2Pacific Hwy 0 0 0 0 2Sunnyvale Rd 0 0 0 1 6Tathra Rd 0 0 0 0 1Valley View Rd 0 0 0 0 2Weeroona Pl 0 0 0 0 2 1 1 1 2 16Ross Glen Main St 0 0 0 10 10Pacific Hwy 0 0 0 1 1Ross Glen Rd 0 0 0 5 5Stage Coach Rd 0 0 5 5 5 0 0 5 21 21Others Pacific Hwy, Johns River 1 3 3 3 4Watson Taylor Rd, Johns R 0 1 1 1 1Wharf Rd, Johns River (est.) 2 2 2 6 10Misty Way, Logans Crossing 0 0 0 0 1


The relative depth of flooding experienced by residential homes affected by the 100 year flood is indicated in Table 4.4. The main points to note are: ► The majority of homes (64%) that would be inundated in a 100 year flood would

be inundated by a depth of over 0.5m; ► Most homes in Dunbogan (103) would be inundated by over 1.0m in the 100 year

flood; ► Most homes in Laurieton (30), North Haven (147), and West Haven (6) would be

flooded by between 0.5 to 1.0m in the 100 year flood; ► Homes in Kendall typically experience a range of inundation depths; ► Should the 100 year flood increase by 0.2m, then an additional 115 homes would

be subject to flooding in this event, the majority of which are located in North Haven (82);

► Should the 100 year flood reduce by 0.2m, then 110 homes would no longer be flooded in this event, the majority of which are also located in North Haven (95).

Table 4.4 Inundation Depths for Homes Affected by the 100 Year Flood

Below Floor Flooding (Number of Houses)

Above Floor Flooding (Number of Houses) Location

< - 0.5m -0.5 to -.2 -0.2 to 0.0 0.0 to 0.2 0.2 to 0.5 0.5 to 1.0 > 1.0m TOTAL

Dunbogan 14 4 4 4 5 44 103 156

Laurieton 58 22 16 2 12 30 17 61

North Haven 70 54 82 95 95 147 43 380



Herons Ck & Misc.1 - - - - - - - -

TOTAL 495 119 115 110 128 236 179 653 1. No flood level information available A provisional hazard categorisation has been determined for every property in the flood damages database. The hazard category is based on the depth and velocity of floodwater over each property and the hazard definition provided in Figure G2 of Appendix G of the Floodplain Management Manual. The provisional hazard categorisation for residential properties subject to flooding in the 100 year flood is indicated in Table 4.5.


Table 4.5 Provisional Hazard Categorisation for Residential Property

Provisional Hazard Category (based on 100 year flood depth and velocity) Location

Low Hazard Medium Hazard High Hazard Total

Dunbogan 6 1 159 166

Laurieton 39 11 51 101

North Haven 249 67 208 524

West Haven & Lakewood 38 0 6 44

Kendall & Rural areas 27 4 25 56

Herons Ck & Misc.1 - - - -

TOTAL 359 83 449 891

1. No flood level information available Main points to note from the hazard categorisation are: ► For the 891 residential properties (containing a house) that is subject to flooding

in the 100 year flood: - 359 would be categorised as Low Hazard (40%) - 83 would be categorised as Medium Hazard (10%) - 449 would be categorised as High Hazard (50%);

► Almost every residential property in Dunbogan that is affected by the 100 year flood (159 of 166) can be categorised as high hazard;

► 50% of residential property in Laurieton (51 of 101) can be categorised as high hazard;

► 40% of residential property in North Haven (208 of 524) can be categorised as high hazard;

► The majority of property in West Haven and Lakewood Village (38 of 44) would be categorised as low hazard;

► In Kendall there are similar numbers of properties categorised as low hazard as there are categorised as high hazard.

4.4 FLOOD RISK MAPPING Different parts of the floodplain are subject to different degrees of hazard, or flood risk. This study recognises that different development controls should apply to different flood risk areas (the approach to floodplain planning adopted for this study is discussed further in Appendix C).


For Camden Haven, it was considered appropriate to divide the floodplain into three different flood risk areas, shown on Figure 4.1. The flood risk areas are: High Flood Risk Land below the 100 year flood that is either subject to a

high hydraulic hazard (ie provisional high hazard in accordance with the criteria outlined in the Floodplain Management Manual) or where there are significant evacuation difficulties.

Medium Flood Risk Land below the 100 year flood level that is not subject to high hydraulic hazard and where there are no significant evacuation difficulties.

Low Flood Risk All other land within the floodplain (ie. within the PMF extent) but not identified as either in a high flood risk or medium flood risk area.

The high flood risk area is where high flood damages, potential risk to life, or evacuation problems are anticipated. Most development should be restricted in this area. The medium flood risk area is where there is still a significant risk of flood damage, but where these damages can be minimised by the application of appropriate development controls. The low flood risk area is that area above the 100 year flood, where the risk of damage is low. Most land uses would be permitted within this area (subject to other considerations such as adequate flood warning and reliable access for evacuation). It is important to note that the available flood information and flood mapping that has been produced is based on existing development. Controls on future development will be necessary to limit filling and other development to ensure that any future cumulative impact is negligible. The hazard mapping is intended to be ultimately incorporated in Council’s GIS computer system. This will provide a valuable source of information for Council to manage the flood risk, and will also assist with future emergency management operations.


5. FLOOD DAMAGES ASSESSMENT 5.1 FLOOD DAMAGES DATABASE A flood damages database has been designed specifically for this study, in order to quantify the impacts of flooding in dollar terms and to allow an economic appraisal of floodplain management measures. The flood damages database contains details of those properties that are potentially affected by flooding. Properties within the database were identified using flood level estimates for the probable maximum flood [Willing & Partners, 1989] and available topographic maps to define the extent of potential flood inundation. Property details were then extracted for this region using Council’s computerised geographical information system (GIS) and rates database. 5.1.1 Property within the Database There are over 1,900 properties included in

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