South Leura Floodplain Management Report FinalJan09...Council does not have an existing flood policy however two relevant planning documents make reference to land subject to inundation

South Leura Floodplain Risk Management Study & Plan

Blue Mountains City Council 29 April 2008 D t N

South Leura Floodplain Risk Management Study & Plan Prepared for

Blue Mountains City Council Prepared by Maunsell Australia Pty Ltd Level 11, 44 Market Street, Sydney NSW 2000, PO Box Q410, QVB Post Office NSW 1230, Australia T +61 2 8295 3600 F +61 2 9262 5060 www.maunsell.com ABN 20 093 846 925

29 April 2008 20018804.00 © Maunsell Australia Pty Ltd 2008 The information contained in this document produced by Maunsell Australia Pty Ltd is solely for the use of the Client identified on the cover sheet for the purpose for which it has been prepared and Maunsell Australia Pty Ltd undertakes no duty to or accepts any responsibility to any third party who may rely upon this document. All rights reserved. No section or element of this document may be removed from this document, reproduced, electronically stored or transmitted in any form without the written permission of Maunsell Australia Pty Ltd.

Quality Information Document South Leura Floodplain Risk Management Study & Plan

Ref 20018804.00

Date 29 April 2008

Prepared by Cathy O'Rourke

Reviewed by Bruce Withnall

Revision History

Authorised Revision Revision

Date Details Name/Position Signature

A 19/12/2006 Draft for Review Kevin Mills Principal Engineer Previously Signed

B 20/12/2006 Draft for Review Andrew Kielniacz Principal Engineer Previously Signed

C 21/12/2006 Final Draft for Review Bruce Withnall Technical Director - Drainage

Previously Signed

D 19/06/2007 Final Draft for Review – additional details for Sublime Point Rd

Bruce Withnall Technical Director - Drainage

Previously Signed

E 29/04/2008 Final Report for Exhibition Bruce Withnall Technical Director - Drainage

Previously Signed

F 20/01/2009 Final Report for Council Bruce Withnall Technical Director - Drainage

D R A F T

Table of Contents Executive Summary i 1.0 Introduction 1

1.1 The Study Area 1 1.2 Project Objectives 1

1.2.1 Phase I – Flood Study 2 1.2.2 Phase II – Floodplain Risk Management Study 2 1.2.3 Phase III – Floodplain Risk Management Plan 2

2.0 Data Collection 4 2.1 Previous Studies 4 2.2 Survey Data 4 2.3 Rainfall and Streamflow Data 4 2.4 Community Consultation 4

2.4.1 Community Questionnaire 5 2.5 Site Investigation 5

3.0 Existing Flood Behaviour 6 3.1 Hydrology 6

3.1.1 Model Description 6 3.1.2 Design Storm Events 8 3.1.3 Calibration 8 3.1.4 Results 9

3.2 Hydraulic Study 9 3.2.1 Model Inputs 9 3.2.2 Hydraulic Model Calibration 10 3.2.3 Results 10

3.3 Accuracy of Results 10 3.4 Flood Hazard 10 3.5 Identification of Affected Properties 11 3.6 Impact on Traffic 12

4.0 Assessment of Flood Damages 14 4.1 Tangible Damages 14

4.1.1 Direct damage 14 4.1.2 Indirect Damage 15

4.2 Intangible Damages 15 4.3 Actual and Potential Damages 15 4.4 Estimation of Flood Damage Costs 16

4.4.1 Basis of Damage Estimates 16 4.4.2 Residential 17 4.4.3 Infrastructure / Public sector 17

4.5 Estimated Average Annual Potential Damages 17 4.5.1 Sensitivity Analysis 19

4.6 Impacts of Floodplain Management Measures 19 5.0 Existing Floodplain Management Measures 20

5.1 Existing Planning Policies 20 5.1.1 LEP 2005 20 5.1.2 Blue Mountains Better Living DCP for Single Dwellings and Subdivsion

Developments – Stormwater 20 6.0 Management Options 21

6.1 Introduction 21 6.2 Key Issues 21 6.3 Community Input 22 6.4 Input from Council’s Emergency Services 22 6.5 Property Modification Measures 22

6.5.1 Voluntary Purchase 22 6.5.2 House Raising 23

South Leura Floodplain Risk Management Study & Plan - 29 April 2008

6.5.3 Development Controls 23 6.5.4 Land Use Zoning Changes 24 6.5.5 Section 149 Certificates 24 6.5.6 Flood Planning Level 24

6.6 Response Modification Measures 26 6.6.1 Flood Education and Awareness 26 6.6.2 Flood Prediction and Warning 27

6.7 Flood Modification Measures 27 6.7.1 Detention Basins 27 6.7.2 Levees 27 6.7.3 Channel Modifications 28 6.7.4 Culvert Upgrades 29 6.7.5 31 Sublime Point Road 31

7.0 Assessment of Options 34 7.1 Benefit Cost Analysis 34

8.0 Floodplain Management Plan 50 8.1 Floodplain Management Plan 50 8.2 Public Exhibition and Summary of Submissions 52

9.0 References 54 Appendix A Figures A Appendix B Survey Data B Appendix C Assessment of Flood Responses C Appendix D Hydrological Model D Appendix E Hydraulic Model E Appendix F Flood Damages F Appendix G Draft Local Flood Policy G Appendix H Mitigation Options H List of Tables Table 1: Summary of South Leura Flooding Issues ii Table 2: Flood Damages - Existing and Options iv Table 3: Summary of Option Ranking v Table 4: Recommended Management Options vii Table 5: Survey Areas 4 Table 6: Initial and Continuing Loss Values 7 Table 7: Summary of Affected Properties in the 100 Year ARI Storm Event 12 Table 8: Summary of Affected Properties - PMF 12 Table 9: Summary of Affected Roads (Unchanged) 13 Table 10: Potential Flood Damages, Existing – Residential 18 Table 11: Options for the Management of Flood Risk 21 Table 12: Assessment of Issues 25 Table 13: Channel Modifications Considered 29 Table 14: Culvert Upgrades Considered 29 Table 15: Sublime Point Road – Flood Management Options 32 Table 16: Screening of Floodplain Risk Management Options 35 Table 17: Assessment of Shortlisted Floodplain Risk Management Options 43 Table 18: Summary of Option Ranking 49 Table 19: South Leura Floodplain Risk Management Plan 50

South Leura Floodplain Risk Management Study & Plan - 29 April 2008

Executive Summary Introduction

Under a Floodplain Management Program a study has been undertaken for the town of South Leura, located in the Blue Mountains. Flooding in South Leura can generally be described as ‘flash flooding’. As the area has grown and urban development increased, the southern side of the town of Leura has experienced an increase in the number and frequency of floods. A 5 yr average recurrence interval (ARI) storm event in 2003 caused extensive damage to several properties and community infrastructure along Spencer Street, Sublime Point Road, Scott Avenue and Gladstone Road. In response to this, Council appointed Maunsell in April 2004 to undertake the South Leura Flood Study, Floodplain Risk Management Study and Floodplain Risk Management Plan. This issue of the report incorporates all three phases of the study and presents the recommended Floodplain Management Plan. The report incorporates additional survey data received (floor levels and Sublime Point Road), a full benefit-cost analysis and the results from the PMF modelling.

Methodology

The study has been undertaken in three phases: • Phase I – Flood Study; • Phase II – Floodplain Risk Management Study; and • Phase III – Floodplain Risk Management Plan. The primary objective of the Flood Study was to define flood behaviour at South Leura. The study has produced information on the nature and extent of the flood problem, flood levels, depths, velocities and flows for a full range of flood events including the 20, 50 and 100 year ARI and the Probable Maximum Flood (PMF). Flood extent maps have been developed and are included in Appendix A, Figures 4.1 to 4.4. The Floodplain Management Study and Plan involved a detailed assessment of the flood mitigation options and floodplain management measures. This portion of the study required a detailed damages assessment, using hazard and risk levels determined as part of the Flood Study. Potential property modification, response modification and flood modification measures have been examined and costs and recommendations developed.

Study Area

The town of Leura is located on the western escarpment of the Blue Mountains, about 85 km west of Sydney NSW. The study area covers most of the sub-catchments on the southern side of Leura, including Jamison Creek Tributary, Valley of the Waters Creek, Gordon Creek and Leura Falls Creek. All these creeks are tributaries of the Coxs River, which flows into Warragamba Dam, Sydney’s drinking water supply. The area spans from the Great Western Highway on the North to Orchard Lane, Hester Road and West Street in the East, to York Street, Wilson Street and Govett Street in the West and Sublime Point Road in the South. The total area covers approximately 550 hectares. The study area is shown in Figure 1, in Appendix A.

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The study area contains areas of natural heritage and ecological significance including hanging swamps, waterfalls, Crown Reserves and National Park. In addition there are large areas of residential development, a commercial centre, several large resorts as well as a Golf Course and Country Club. The bushland and sedge swamp ecological communities influence the hydrology and water quality of the creeks, as well as providing habitat for flora and fauna including several species that are rare, vulnerable or endangered. The catchment of South Leura is characterised by moderate to steep slopes and flow is conveyed via a mixture of natural channels, modified grass and concrete lined channels and culverts. The land use is primarily zoned residential with some areas of business (Leura Mall), industrial and recreational land use.

Summary of the flood problem

Many of the creeks and streams throughout South Leura run though properties or adjacent to them. As such many houses and buildings are located near to or on the overland flow path. Table 1 provides a summary of the flood problem in Leura. The flood hazard levels are predominantly high due to the steep nature of the channels and streams and the rapid rate of rise of the flood waters.

Table 1: Summary of South Leura Flooding Issues

100 year ARI storm event

PMF

Total Number of Properties 2437

Number of flood liable properties 205 252

Number of properties with houses in flood path 25 51

Number of houses flooded above floor level 8 18

Main areas with houses at risk Scott Ave Abbey St Govett St

Spencer St Gladstone Rd Everglades St

Sublime Point Rd

Critical roads flooded in 100 year ARI storm event

Scott Ave Wilson St

Magdala St Kanimbla St

Govett St Gladstone Ave

It should be noted that the above summary doesn’t include properties at risk from nuisance flooding. Houses that have experienced nuisance flooding were identified in the community questionnaire, during the data collection stage. Nuisance flooding can include surface runoff from a neighbouring property, a property located on the low side of road, surface runoff or overland flows from a road and flooding from blocked stormwater infrastructure. Nuisance flooding has not been modelled as part of our flood study; the modelling has only included creek flooding. A separate study specifically looking at overland flow and nuisance flooding would be required and this could initially be based on the results from the community questionnaire.

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Existing Planning Controls

Council does not have an existing flood policy however two relevant planning documents make reference to land subject to inundation and to stormwater management. These include LEP 2005 and the Blue Mountains Better Living DCP. The Draft Local Floodplain Risk Management Policy developed as part of this study, is expected to be incorporated into the Blue Mountains Better Living DCP.

Floodplain Risk Management Measures

The Floodplain Development Manual (April 2005) defines three ways of managing flood risk. All three types of management measures were considered in this Study, and the community consulted to identify an integrated and effective mix, appropriate for South Leura. These types of measures are: • Flood modification - Modifying the behaviour of the flood itself • Property Modification - Modifying (i.e. house raising) or purchasing existing properties and/or by

imposing controls on property and infrastructure development and • Response Modification - Modifying the response of the population at risk to better cope with a

flood event. Flood Modification Measures are a common and proven means of reducing damage to existing properties at risk. Measures considered in this study included detention basins, levees, channel modifications and culvert upgrades. Property Modification Measures, such as effective land use controls, are essential if the growth in future flood damage is to be contained. Measures considered in this study included adoption of Flood Planning Levels, Section 149 Certificates, Land Use Zoning changes, Development Controls and voluntary purchase. Response Modification Measures are the most effective means of dealing with the continuing flood problem, which is the risk that remains from floods after other measures are in place. Measures considered in this study included flood education and awareness and flood prediction and warning.

Economic Evaluation - Flood Damages Assessment

At the broadest level, flood damages are either financial or social in nature and are often respectively referred to as the tangible and intangible costs of flooding. The total financial “damage” caused by a flood can be separated into two major components, the cost of the direct damage to inundated property and the cost of the indirect damage associated with the disruption of social, community and business relationships during the aftermath of a flood. The average annual potential damage (AAD) is equal to the total damage caused by all floods over a long period of time divided by the number of years in that period. It has been calculated using the total financial potential damages (direct and indirect costs) for a range of flood event magnitudes/frequencies. Table 2 shows the potential AAD for residential properties and infrastructure for each catchment and the reduction in AAD for each shortlisted option that has been hydraulically modelled. Benefits of each option were calculated as present value for a 40 year design life using a 7% interest rate.

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Table 2: Flood Damages - Existing and Options

Existing AAD Revised AAD Option

($) ($) PV of Benefit ($) (1)

CATCHMENT A 1 11,520 10,102 21,234 2 11,520 11,029 7,352 7 11,520 11,296 3,354 8 11,520 10,396 16,831 9 11,520 10,102 21,234

CATCHMENT B 12, 13 31,918 29,362 38,275

14 31,918 31,399 7,772 17 31,918 29,268 39,682

20, 21 31,918 28,925 44,819 CATCHMENT C

29 17,574 13,506 60,916 34 17,574 16,840 10,991 36 17,574 16,906 10,003 37 17,574 14,820 41,240

CATCHMENT D 39 2,065 2,062 45

CATCHMENT E 55 8,878 8,464 6,199 57 8,878 7,312 23,450 59 8,878 8,540 5,061 60 8,878 5,295 53,653

CATCHMENT F 43 13,774 8,456 79,631 47 13,774 11,545 33,376

(1) Present value of benefit represent the savings achieved over the 40 year design life

Assessment of Floodplain Risk Management Measures

A screening process was used reduce the initial long list of 61 options down to 39 options warranting further investigation. The detailed assessment of the 39 shortlisted options to determine the final recommendations involved consideration of the following factors: • Economic evaluation – the indicator adopted to rank options on economic merit was the benefit

cost ratio (BCR). Benefits were evaluated as the reduction in average annual damages achieved by each option.

• Non-economic evaluation: - Hazard level, in terms of risk to life and to property – indicated by the provisional hazard

categories; - Environmental and social impacts – including intangible damages and benefits - Whether an evacuation route is affected and the impact on emergency management – this is

an important factor which is not reflected by the BCR as flood access can often be improved without significant reduction in residential flood damages. Scott Avenue, Kanimbla St, Magdala St, Wilson St and Govett St were identified as critical access routes which should ideally remain trafficable in the 100 year ARI event.

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Table 3 provides a summary of the economic and non-economic ranking of options and provides a list of recommended options in order of overall rank.

Table 3: Summary of Option Ranking

Option BCR Economic Rank

Non-economic

Rank

Average Overall Rank

Main reasons for recommendation

29 1.85 1 3 2 1 Highest economic benefit, social benefit

Requires further investigation

43 0.31 6 1 3.5 2 Critical access route, high economic benefit

47 1.04 2 5 3.5 3 Low cost, social benefit

35 6 6 4 Potential risk reduction and environmental benefits


37 0.98 3 10 6.5 5 High economic benefit, social benefit

Not required if option 35 feasible

1 0.22 8 8 8 6 Critical access route

20, 21 0.1 16 2 9 7 Hazard reduction, high economic benefit

60 0.13 14 4 9 8 High social and economic benefit

14 0.32 5 13 9 9 Low cost, social benefit


12, 13 0.16 10 9 9.5 10 Improved access, high social benefit

8 0.7 4 15 9.5 11 Requires further investigation

57 0.11 15 7 11 12 Risk reduction, social benefit


46 12 12 14 Critical access route

9 0.26 7 17 12 15 Economic benefit

Not recommended if option 7 and 8 feasible

17 0.16 11 14 12.5 16 Economic benefit

34 0.2 9 16 12.5 17 Improved access, low priority


27 18 18 19 Risk reduction

36 0.08 17 20 18.5 20 Low priority

45 19 19 21 Environmental benefit, low priority

59 0.07 18 22 20 22 Not recommended

31 Sublime Point Road

At the request of Council a more detailed analysis was undertaken for 31 Sublime Point Rd, which has experienced a number of above-floor flooding events in recent years. Several options were

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considered. Council will need to review the feasibility of options and carefully consider the option to purchase the property or relocate the dwelling higher up the site. A short term solution, Council could consider undertaking flood proofing measures combined with landscaping work to allow flood waters to drain more quickly from 31 Sublime Point Rd.

Floodplain Risk Management Plan

Under the NSW Government’s Floodplain Management Manual, the primary objectives for a Floodplain Risk Management Plan are: • To reduce the social and economic impact of flooding on individual owners and occupiers of flood

prone property; and • To reduce private and public losses resulting from floods. Council has a duty of care in advising property owners, occupiers and developers on the extent and level of flooding and in making decisions with regard to an appropriate flood planning level. Some of the benefits gained by the existing flood affected community and residents from undertaking the recommended management actions include: • A reduction in average annual damages (whether by the reduced occurrence and extent of over

floor flooding; the reduced number of dwellings incurring above floor flooding; the reduced number of flooded allotments; and/or the reduced number of overall dwellings affected by flooding);

• A reduction in flood hazard levels; • Improved and effective flood access; • A reduction in adverse social impacts (including improved community protection in major floods); • Improved protection of community infrastructure and essential services; and • Improved community responses to flood risk management (including better evacuation

management, better flood awareness/warning). Table 4 lists the recommended options for adoption and implementation.

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Table 4: Recommended Management Options

Option Number Management Option Cost ($) BCR Overall

Rank Priority Rating

Property Modification Measures

48 Incorporate Draft Local Floodplain Risk Management Policy in Blue Mountains Better Living DCP

N/A - - High

49 Land Zoning Changes N/A - - High

50 Adopt 100 Year ARI flood level + 500mm as the flood planning level N/A - - High

51 Section 149 Certificates N/A - - High

60 Voluntary purchase of 31 Sublime Point Rd 400,000 0.13 8 Medium

Response Modification Measures

52 Council to implement a Flood Education and Awareness program N/A - - High

53 Council to present SES with flooding information presented in this report

N/A - - High

Flood Modification Measures Culvert Upgrades

1 Corner of Kanimbla St and Wilson St 98,000 0.22 6 High

2 Magdala St 58,000 0.13 13 Medium

12 Abbey St (south of Craigend) 84,000

13 Abbey St (south of Craigend) 150,000 0.16 10

Medium - Adopt only if

option 14 is not feasible

17 Megalong St to Craigend St 254,000 0.16 16 Low 20 Craigend St (east of Hartley Esp) 72,000

21 Craigend St, west side of Spencer St, 390,000

0.10 7 High

34 Gladstone Rd (south of Wentworth Ave) 56,000 0.2 17 Low

43 22 Gladstone Road to 18-20 Scott Ave 267,000 0.31 2 High

46 Scott Ave (east of Herbert St) 164,000 - 14 Medium

57 Sublime Point Rd 205,000 0.11 12 Medium

Channel Modifications

9 Wilson St to Govett St 81,000 0.26 15

Low - Not required if

options 7 and 8 are feasible

27 Lachlan Ave to Craigend St (east of Victoria St) 40,000 -

19

Low

36 Western side of Everglades Ave from Northcote Road to Easter St 124,000 0.08 20 Low

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37 West of Gladstone Road (between No’s 101 and 103-5) 42,000 0.98 5

High - Not required if

option 35 is feasible

45 Channel running behind houses along Scott Ave (numbers 18 to 42) 103,000 - 21 Low

Detention Basins

35 Feasibility Study for Golf Course upstream of sub-catchment C2 N/A - 4

High - Further investigation

required Levees/Flood Proofing

7 37 Govett St (Further investigation) 24,000 0.14 18 Low - Further investigation

required

8 50 Govett St (Further investigation) 24,000 0.70 11

Medium - Further

investigation required

14 Abbey St (Further investigation) 24,000 0.32 9

Medium - Further


29 4 Everglades Ave 33,000 1.85 1 High

47 9 Hester Place 32,000 1.04 3 High

Funding

Under the NSW Government’s Floodplain Management Program, financial assistance is provided to Councils for the implementation of floodplain risk management measures. Under current arrangements, funds are provided on a 2:1 basis, i.e. Councils fund one third of implementation costs. The provision of State funds is dependent on State-wide priorities and the availability of funds under the Floodplain Management Program.

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1.0 Introduction The urban area of the city of Blue Mountains drains approximately 60 sub-catchments. Most of these sub-catchments are not subject to major flooding. However, some localised flooding has been reported. Due to the development during the last two decades, the frequency of localised flooding has worsened. This has put more properties at risk of flooding. Thus, accurate definition of flood affected lands and subsequent plans to mitigate potential flood impacts are required for flood prone sub-catchments. The southern side of the town of Leura has experienced an increase in the number and frequency of flood event in recent years. Maunsell has confirmed that it was a 5 yr Average Recurrence Interval (ARI) storm event in 2003 that caused extensive damage to several properties and community infrastructure along Spencer Street, Sublime Point Road, Scott Avenue and Gladstone Road. Residents in these areas have raised their concern and requested support from Council to alleviate the impact of flooding in the future. Due to the recent flood events and damage to properties, Council engaged Maunsell to undertake this study in order to identify locations where flooding poses a significant level of risk and where potential flooding hazards may restrict future development. This was the basis for undertaking the initial stage of the project, the Flood Study. The second phase, the Floodplain Management Study identifies options to mitigate future flooding and the Floodplain Management Plan prioritises the recommended actions.

1.1 The Study Area The town of Leura is located on the western escarpment of the Blue Mountains, about 85 km west of Sydney NSW. The study area covers most of the sub-catchments on the southern side of Leura, including Jamison Creek Tributary, Valley of the Waters Creek, Gordon Creek and Leura Falls Creek. All these creeks are tributaries of the Coxs River, which flows into Warragamba Dam, Sydney’s drinking water supply. The area spans from the Great Western Highway on the North to Orchard Lane, Hester Road and West Street in the East, to York Street, Wilson Street and Govett Street in the West and Sublime Point Road in the South. The total area covers approximately 550 hectares. The study area is shown in Figure 1, in Appendix A. The study area contains areas of natural heritage and ecological significance including hanging swamps, waterfalls, Crown Reserves and National Park. In addition there are a large areas of residential development, a commercial centre, several large resorts as well as a Golf Course and Country Club. The bushland and sedge swamp ecological communities influence the hydrology and water quality of the creeks, as well as providing habitat for flora and fauna including several species that are rare, vulnerable or endangered.

1.2 Project Objectives The overall objective of the study is to develop a Floodplain Risk Management Plan for South Leura that addresses the existing, future and continuing flood problems, in accordance with the NSW Government's Flood Policy, as detailed in the NSW Floodplain Development Manual (April 2005). Overall, the study has been undertaken in three phases: • Phase I – Flood Study; • Phase II – Floodplain Risk Management Study; and • Phase III – Floodplain Risk Management Plan.

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1.2.1 Phase I – Flood Study

The primary objective of the Flood Study was to define flood behaviour at South Leura. The study has produced information on the nature and extent of the flood problem, flood levels, depths, velocities and flows for a full range of flood events under existing catchment and floodplain conditions. The Flood Study was a key part of the project, with the correct assessment of the flooding in localised areas being critical to the next two stages. Local experience and modelling has shown that the effects of flooding in Leura are generally localised. The Flood Study involved undertaking hydrologic and hydraulic modelling to satisfy the study objectives. The study formed the basis for the subsequent Floodplain Management Study and Plan, where a detailed assessment of flood mitigation options and floodplain management measures has been undertaken. The Flood Study identified the hydraulic category and hydraulic hazard category (high hazard or low hazard) for flood prone land. In addition, the study identified aspects of flooding behaviour requiring special consideration.

1.2.2 Phase II – Floodplain Risk Management Study

During this phase a detailed assessment of flood mitigation options and floodplain management measures was undertaken. The objectives of this phase included to: • Review Council’s existing environmental planning policies and instruments including Council’s

long term planning strategies for the study area; • Identify works, measures and restrictions aimed at reducing the social, environmental and

economic impacts of flooding and the losses caused by flooding on development and the community, both existing and future, over the full range of potential flood events. Council is looking for innovative solutions to the management of the flood hazards within the study area and requires effective community consultation and participation throughout the Study;

• Assess the effectiveness of these works and measures for reducing the effects of flooding on the community and development, both existing and future;

• Consider whether the proposed works and measures might produce adverse effects (environmental, social, economic, or flooding) in the floodplain and whether they can be minimised;

• Examine the present flood warning system, community flood awareness and emergency response measures in the context of the NSW State Emergency Service's developments and disaster planning requirements;

• Examine ways in which the river and floodplain environment may be enhanced by preparing a strategy for vegetation planning that will create a valuable corridor of vegetation without having a detrimental effect on flooding; and

• Identify modifications that are required to current policies in the light of investigations.

1.2.3 Phase III – Floodplain Risk Management Plan

This phase involved developing a Floodplain Management Plan based on the outcomes of the Floodplain Management Study. In addition to the modelling work the information received from the community consultation was fed into the Floodplain Management Plan to highlight works that will aim to give great benefit to localised flooding situations.


The Plan details how the flood prone land needs to be managed. The objectives of this phase were to: • Make recommendations to reduce the flood hazard and risk to people and property in the existing

community and to ensure future development is controlled in a manner consistent with the flood hazard & risk;

• Make recommendations to reduce private and public losses due to flooding; • Make recommendations to protect and where possible enhance the river and floodplain

environment; • Be consistent with the objectives of relevant State policies, in particular, the Government’s Flood

Prone Lands and State Rivers and Estuaries Policies and satisfy the objectives and requirements of the Environmental Planning and Assessment Act, 1979;

• Ensure that the Floodplain Management Plan is fully integrated with Council’s existing corporate, business and strategic plans, existing and proposed planning proposals, meets Council’s obligations under the Local Government Act, 1993 and has the support of the local community;

• Ensure actions arising out of the management plan are sustainable in social, environmental, ecological and economic terms;

• Ensure that the floodplain management plan is fully integrated with the local emergency management plan (flood plan) and other relevant catchment management plans; and

• Establish a program for implementation and a mechanism for the funding of the plan and should include priorities, staging, funding, responsibilities, constraints, and monitoring.


2.0 Data Collection

2.1 Previous Studies The following studies undertaken in the area relevant to this flood study were obtained from Council: • Draft Environmental Assessment - Sublime Point, Leura (Proposed diversion of a stormwater

outlet at Orchard Lane, Sublime Point, Leura - November 2001); • Option for control of gully erosion in a Valley Swamp at Leura (September 2003); and • Investigation of Minor Flooding at No. 31 Sublime Point Road, Leura (January 2004).

2.2 Survey Data Council provided relevant GIS data and aerial photography for this study. A full list is included in Appendix B. In addition survey data was collected for areas identified as flooding “hotspots” by both the questionnaires and the preliminary modelling. These areas are identified in Table 5 below.

Table 5: Survey Areas

Catchment Area A • Kanimbla St to Clarence St

• Culvert at Megalong St

B • Craigend St to Abbey St • Megalong St to Spencer St

C • Craigend St to Northcote Rd • Gladstone Rd

E • Sublime Point Rd

F • Morvan Rd to Scott Ave In some areas, the surveys received did not cover a wide enough area to define the flooded area. As a result, the original GIS information was used in combination with the survey data for the flood mapping for these sections. This was considered sufficient to allow an assessment of the flood risk.

2.3 Rainfall and Streamflow Data A search of relevant rainfall data was undertaken. Relevant pluviograph data and daily rainfall data was obtained from the Bureau of Meteorology and Sydney Water. More information of what rainfall data was obtained is included in Appendix E. No streamflow data was available.

2.4 Community Consultation An essential component in the development of this flood study and floodplain management plan has been community consultation. Community consultation has included a community questionnaire and consultation with community members through meetings with the Floodplain Management Committee and specific site visits. In addition, Council will conduct further consultation during the public exhibition of the Floodplain Risk Management Plan.


2.4.1 Community Questionnaire

As part of the data collection stage of the flood study, the South Leura Flood Study and Floodplain Risk Management Study Community Questionnaire was sent out to all households within the study area. A copy is included in Appendix C. The questionnaire aimed to determine areas prone to flooding and to obtain local knowledge about flood events including flood levels and frequency of flooding events. It also questioned residents about their knowledge of Council’s flood policy. An assessment of Flood Responses has also been included in Appendix C and the results are shown on Figure 5, in Appendix A.

2.5 Site Investigation Site investigations were undertaken to confirm catchment parameters and drainage network details. Specifically, the following tasks were undertaken during the site visits: • Confirmation of flow paths; • Identification of data missing from the pit and pipe network provided as part of the GIS

information by Council, including pipe sizes and location; • Confirmation of channel sizes, depths, width and roughness values; • Discussions with some residents of flood affected properties; • Investigation of flood affected areas identified from the Community Questionnaire; • Confirmation of survey data; and • Assessment of houses/buildings impacted by the 100 year ARI storm event.


3.0 Existing Flood Behaviour

3.1 Hydrology XP-RAFTS (Runoff Analysis and Flow Training Simulation software, RAFTS) was selected for the hydrologic modelling of the catchment after consultation with the Council. This software is recommended by Australian Rainfall & Runoff and is a widely used for urban and rural catchment analysis for flood studies. The output from RAFTS includes flow hydrographs, which provide input to a hydraulic model for analysis of the network. The tasks involved in the hydrologic modelling included the following: • Development of sub-catchment boundaries; • Development of a catchment and network plan; • Determination of hydrology model parameters and input data; • Analysis of the model for completeness and accuracy of flows; • The model was run for 100 year ARI storm event and compared with Probabilistic Rational

Method estimates; • Identification of peak flow durations; • Development of the model to include additional required storm events, including the 20, 50-year

ARI storm events and the PMF; and • Generation of hydrographs to export to SWMM.

3.1.1 Model Description

There are 6 catchments in the South Leura region that have been included in the model. These are shown in Figures 3.1 to 3.4 in Appendix A. These catchments were determined based on the four creeks within the study area and catchment characteristics including land use and topography. The catchments were further broken down into sub-catchments, based on the locations of hydraulic structures and areas of potential hazard as determined from the questionnaire results and discussion with residents and Council staff members. As can be seen from the catchment plan there are sections within the study area that do not form part of the main catchments. These areas are located away from major watercourses and have no reported flooding problems. Therefore it has been judged that these properties are not at risk from creek flooding and as such have been excluded from the model.

Model Catchment Parameters

The sub-catchment parameters in RAFTS are based on site visits, best practice and on topographic information provided. In general, a sub-catchment node is defined by the following parameters: • Catchment area (ha); • Catchment slope (%); • Fraction impervious (%); and • Roughness value.


Catchment Area and Slope

The sub-catchment area has been determined from topographic data and from the pit and pipe network information provided by the Council. The area and slope were calculated using MapInfo and 12d.

Fraction Impervious

The fraction impervious values for each sub-catchment have been determined from aerial photography and site inspection. Existing and fully developed values have been determined, with the fully developed values being determined from Councils Local Environment Plan 2005 (LEP 2005).

Roughness Values

The roughness values for each sub-catchment have been determined from aerial photography and site inspection. A roughness of 0.018 was used for impervious catchments and 0.04 was used for pervious catchments.

Hydrograph Routing

A lag time was calculated for each reach based on the stream length and an average velocity of 1m/s.

Initial and Continuing Rainfall Loss

Initial and continuing rainfall loss parameters were also input into the model. Values given in AR&R (1987, 1999) were used as a general guide, however, rainfall losses are variable depending on the type of underlying soil and level of development. The values used in the models for this study are shown in Table 6.

Table 6: Initial and Continuing Loss Values

100 year ARI storm event PMF Pervious

Catchment Impervious Catchment

Pervious Catchment

Impervious Catchment

Initial Loss (mm) 20 10 0 0 Continuing Loss (mm/hr) 2.5 2.5 1 1

Catchment Descriptions

A description of each of the five catchments is provided below. Detailed information is provided in Appendix D and the catchment areas are shown in Figure 1 in Appendix A.

Catchment A

Catchment A covers an area of 207 hectares and forms part of the Leura Falls Creek catchment. The catchment is characterised by moderate to steep slopes and flow is conveyed via a mixture of natural channels, modified grass and concrete lined channels and culverts. The land use is primarily zoned residential with some areas of business (Leura Mall), industrial and recreational land use.

Catchment B

Catchment B forms part of the Gordon Creek catchment and covers an area of 100 hectares. The catchment is characterised by moderate to steep slopes. Flow is conveyed by pit and pipe drainage systems and modified grass and concrete lined channels with culverts higher in the catchment. Further downstream flow is conveyed by natural grass and rock lined channels. The land use is primarily residential with some areas of business (including Leura Mall) and recreational land use.


Catchment C

Catchment C is part of the Gordon Creek catchment, covering an area of 56 hectares. The catchment is characterised by moderate to steep slopes and flow is conveyed via a mixture of natural channels, modified grass and concrete lined channels and culverts. The land use is mainly residential with smaller areas of recreational land use, retirement village and environmentally protected areas.

Catchment D

Catchment D is a small catchment (12.3 hectares) that also flows to Gordon Creek. The catchment is characterised by moderate slopes in the upper catchment and steep slopes in the lower catchment. The catchment includes the golf course and flows via pits and pipes to a modified open channel which discharges to a natural channel further downstream. The land use is residential and recreational.

Catchment E

Catchment E covers an area of 48.6 hectares and is part of the Gordon Creek catchment. The catchment includes the golf course to the north. The catchment has moderate to steep slopes and flow is conveyed by a mixture of natural channels, modified grass and concrete lined channels and culverts. The land use is a mixture of residential, recreational and environmental protection areas.

Catchment F

Catchment F is part of the Valley of the Waters Creek catchment. It covers an area of 133 hectares and has moderate to steep slopes. Flow is conveyed via a mixture of natural channels, modified grass and concrete lined channels and culverts. The land use is primarily zoned residential with small recreational areas.

3.1.2 Design Storm Events

RAFTS has the design rainfall intensities from AR&R (1987) built in. Design events for 20, 50 and 100 year ARI storm events have been run for durations between 15 mins and 72 hours ensuring that the critical duration event for each area of interest can be determined. The PMF was determined using the AR&R (1998). The IFD parameters for South Leura, taken from ARR Vol 2 (2001), entered into RAFTS are as follows:

2yr, 1hr - 31 mm/h 2yr, 12hrs - 9 mm/h 2yr, 72 hrs - 3 mm/h 50yr, 1hr - 61.5 mm/r

50yr, 12hrs - 18.8 mm/h 50yr, 72hrs - 7 mm/h

F2 - 4.3 F50 - 15.75 G - 0.07

3.1.3 Calibration

The options for calibration of the hydrologic model included verification using the Probabilistic Rational Method and results from previous drainage studies conducted in the Study Area. However, results from previous studies did not allow for comparison and as such the RAFTS model was verified using the Probabilistic Rational Method.


Verification using the Probabilistic Rational Method is typically only applicable where there is minimal channel storage that might attenuate flows, and involves evaluating the peak flows predicted against Probabilistic Rational Method calculations for an equivalent catchment. The results showed that the resulting peak flows are generally within ±10% of the Probabilistic Rational Method. The results are included in Appendix D.

3.1.4 Results

The RAFTS model was run for a range of storm durations between 15 mins and 72 hours in order to determine the critical peak flow for each sub-catchment. The results for durations between 15 mins and 12 hours are shown in Appendix D. The results for longer duration storms have been excluded as the sub-catchments have a critical storm duration of 1.5 to 2 hours. All of the catchments (A-F) had a peak flow at the outlet corresponding to the 2 hour storm. For the PMF, the peak duration was 15 minutes. Flow hydrographs for the critical storm durations were imported into SWMM, for the 20, 50 and 100 year ARI storm events and the PMF.

3.2 Hydraulic Study The flood routing package XP-SWMM (Storm Water Management Model, SWMM) was selected for the hydraulic modelling component of the flood study. XP-SWMM is widely used throughout Australia and is able to model the stream, floodplain, overland flow paths and stormwater network. This XP package interacts with all XP products allowing for flow hydrographs from RAFTS to be directly inputted into SWMM. The methodology used for developing the hydraulic model for the flood study is outlined below: • Site inspections to confirm flow paths and develop roughness values; • Inputting of hydraulic structures into the model; • Generation of cross-sections using 12d and inputting into SWMM; • Importing hydrographs from RAFTS into SWMM; • Calibration of the hydraulic model; and • Modelling of design storm events. The hydraulic model includes all creeks and major watercourses within the study area. A separate model was created for each catchment.

3.2.1 Model Inputs

A summary of the input data is included in Appendix E. Figure 2 shows the drainage network, provided by the Council and Figures 3.1 to 3.4 show the model network set up in SWMM. These figures are included in Appendix A. This section explains how the inputs were derived.

Hydraulic Structures

Hydraulic structures that form part of the main watercourses including box culverts, pipes and pits were input to the model. Information on culvert sizes, pit and pipe levels were primarily obtained from GIS data provided by Council. The MapInfo tables included information on pipe sizes, pit and pipe depths, however no information on invert levels was provided. The pit and pipe invert levels were estimated using the information provided and the ground contours. The pipe invert level was taken as the bottom of the pit. This method was considered adequate by Council. In the flood prone areas defined in Section 2.2 additional survey was undertaken and the data input to the model.


Cross Sections

The survey data and the ground contours were imported into 12D and cross sections generated. For each length of channel section between two nodes, a channel cross-section which best represented the typical channel section between the two nodes was selected. Where channels had been modified through the process of urban development and the contour information did not accurately represent this, information obtained from site visits and from survey data was manually input to the model.

Roughness coefficients

Channel roughness values were based on site investigations and an assessment of the channel condition and the density of vegetation. Many of the channels have been modified through the process of urbanisation. Channels that have not been modified typically have higher roughness values. The values adopted are presented in Appendix E.

Downstream Boundary Conditions

In all models “free outflow” was selected as the downstream boundary condition. This was considered appropriate due to downstream conditions, which are unlikely to create any backwater effects due to the steep stream slopes.

3.2.2 Hydraulic Model Calibration

The hydraulic models developed in SWMM were calibrated against historical flood events. Three events were modelled, including 11 March 2003, 26-31 March 2002 and 28 February 2001. The results of the modelling did not allow verification of the model. This was primarily due to the lack of accurate observed flood level information and also the pluviograph data obtained was from Katoomba and not in close proximity to the Leura catchment area. A full description of the calibration process and results obtained is included in Appendix E.

3.2.3 Results

The hydraulic models were run for the peak storms as described above. The detailed results are included in Appendix E. Figures 4.1 to 4.4 show the extent of flood inundation for the 100 year ARI storm event and PMF. It should be noted that the Flood Planning Level (FPL) is not shown on these figures. The adopted FPL is outlined further in Section 6.5.6 and is 0.5m above the 100 year ARI flood levels.

3.3 Accuracy of Results The accuracy of the results presented in this report is dependent upon the quality of the data used in the models. Every attempt was made to ensure that the results presented are as accurate as possible. At a number of critical places the model results and the subsequent assessment of risks are based on a combination of the survey data, the MapInfo databases, contour information and number of site visits.

3.4 Flood Hazard The level of hazard across a floodplain needs to be understood by landowners and floodplain managers to assist in the preparation of an appropriate floodplain risk management plan. The Floodplain Development Manual (April 2005) outlines two provisional hazard categories based on hydraulic characteristics ie. depth and velocity of floodwaters. These are defined by the manual as: • High hazard – possible danger to personal safety; evacuation by trucks difficult, able-bodied

adults would have difficulty wading to safety, potential for significant structural damage to buildings


• Low hazard – if necessary trucks could evacuate people and their possessions; able-bodied adults would have little difficulty in wading to safety.

These provisional categories can then be refined by giving consideration to a number of factors that impact upon flood hazard, including: • Size of the flood; • Effective warning time; • Flood readiness; • Rate of rise of floodwaters; • Depth and velocity of floodwaters; • Duration of flooding; • Evacuation problems; • Effective flood access; and • Type of development. Provisional hazard categories have been assigned to the flooded areas in the study area based on depth and velocity for the 100 year ARI storm event. The criteria used were based on Figure L2 in the Floodplain Development Manual (April 2005). The results have been mapped and are shown in Figures 6.1 to 6.4, included in Appendix A. The provisional flood hazard categories are predominantly high due to the steep nature of the channels and streams resulting in high velocities. Flooding in the area is essentially “Flash flooding” and is characterised by a rapid of rise of the flood waters. Peak flows generally occur within the first hour of the storm. There will therefore be a low effective warning time. It is impossible to predict when larger storms will occur, so flood readiness will be reduced. No reduction in flood hazard category was made for these factors. The flood hazard categories have been used in prioritising mitigation measures. Priority has been given to options in high hazard locations, where there is a risk to public safety, particularly where critical access routes are affected. Some details of hazard categories at road crossings are provided in Table 8.

3.5 Identification of Affected Properties A detailed assessment of affected properties has been carried out. This involved identifying all flood-affected properties and then determining the extent of potential damages to any buildings. The findings for the 100 year ARI storm event and the PMF are summarised in Tables 7 and 8. A full list of properties affected is included in Appendix F. The results were used as a basis for the damages assessment. Note that properties located outside of the models may be affected by flooding through overland flow. Only flood liable properties within the extent of the models have been identified. The model encompasses all areas at risk of creek flooding.


Table 7: Summary of Affected Properties in the 100 Year ARI Storm Event

Catchment Area

Total Number of Properties

Number of flood liable properties

Number of properties with flood

prone buildings

Number of houses

flooded over floor level

A 784 60 2 0 B 664 52 11 2 C 272 32 5 2 D 65 7 0 0 E 160 21 2 2 F 492 33 5 2

TOTALS 2437 205 25 8

Table 8: Summary of Affected Properties - PMF

Catchment Area

Total Number of Properties

Number of flood liable properties

Number of properties with flood

prone buildings

Number of houses

flooded over floor level

A 784 74 10 3 B 664 61 17 6 C 272 41 9 2 D 65 11 1 1 E 160 21 4 2 F 492 44 10 4

TOTALS 2437 252 51 18 It should be noted that 6 properties within the study area are also flooded above floor level in the 20 and 50 year ARI storm events. Catchments E and F both have 2 properties affected in these design events.

3.6 Impact on Traffic Table 9 provides a list of roads overtopped in the 100 year ARI storm event and gives an assessment of the hazard level and the trafficability of the road accordingly. The table also provides the estimated frequency of the storm events at which the road is overtopped.


Table 9: Summary of Affected Roads (Unchanged)

100 Year ARI Storm Event Results

U/S Node

D/S Node Road Depth

of Flow (m)

Velocity (m/s)

Hazard Level Trafficable

Duration of

flooding (mins)

Overtopping Flood Size

A1-1 A1-6 Corner of Kanimbla St and Wilson St

0.34 1.30 High No 54 <20Yr

A2-1 A2-4 Magdala St 0.31 1.40 High No 87 <20Yr

A2-2 A2-3 Kanimbla St (east of Wilson St)

0.20 1.20 Low Yes 140 <20Yr

A1-2 JA-1 Wilson St (south of Kanimbla St) 0.43 1.50 High No 80 <20Yr

A3-1 JA-3 Govett St (south of Kanimbla) 0.16 1.20 Low Yes 103 <20 Yr

B1-1 B1-3 Craigend St (west of Abbey St)

0.25 1.30 High No 102 <20Yr

B1-6 B1-7 Abbey St (south of Craigend) 0.31 1.10 High No 47 <20Yr

B2-1 B2-4 Megalong St (east of Hartley Esp)

0.20 1.10 Low Yes 53 <20Yr

B2-2 B2-5 Craigend St (east of Hartley Esp) 0.54 1.60 High No 68 <20Yr

C1-1 C1-2 Lachlan Ave (east of Victoria St)

0.20 0.70 Low Yes 19 <20Yr

C1-3 C1-4 Craigend St (east of Evergades Ave)

0.20 1.00 Low Yes 8 <20Yr

C1-5 C1-6

Corner of Northcote Road and Everglades Ave)

0.50 1.20 High No 51 20-50Yr

C1-8 C1-10 Easter St (west of Everglades Ave)

0.24 1.00 Low Yes 8 <20Yr

C2-3 C2-4 Gladstone Rd (south of Wentworth Ave)

0.22 1.10 Low Yes 55 <20Yr

D-1 D-2 Gladstone Rd (south of Blaxland Rd)

0.14 0.60 Low Yes 49 <20Yr

F1-1 F1-5 Morvan Rd (east of Gladstone Road)

0.18 1.10 Low Yes 19 <20Yr

F1-13 F1-14 Scott Ave (east of Gladstone Rd) 0.36 1.50 High No 66 <20Yr

F1-10 F1-3 Scott Ave (east of Herbert St) 0.29 1.10 High No 29 <20 Yr


4.0 Assessment of Flood Damages Over the past two decades, procedures have been developed to arrive at objective estimates of the financial impact of flooding on properties, disruption, lost income, clean-up and such like. A flood has a variety of effects on the lives and livelihoods of people whose possessions and places of residence or employment are inundated. Because of this, the types and costs of flood damage can be categorised in a number of ways. At the broadest level, flood damages can be defined as: • Tangible damages – those for which a monetary value can be assigned • Intangible damages – those which cannot easily be quantified in monetary terms Sections 4.1 and 4.2 provide an explanation of these flood damage categories and the subcategories that need to be quantified to undertake an assessment of flood damages.

4.1 Tangible Damages Tangible damages are financial in nature and fall into two basic categories, direct and indirect.

4.1.1 Direct damage

Direct damages are caused by the physical contact of flood water with damageable property. These damages may include the cost of repairs or replacement costs and apply to commercial and residential building structures and contents, infrastructure including electricity, gas, water supply and sewerage reticulation. It can also include damage to motor vehicles and other plant and equipment. Direct damages is commonly assessed in three categories: • Internal – building contents, costs of cleaning and repair or replacement, eg. damage to carpets

and furniture, appliances, services (electricity, telephone, water supply and sewerage) and clothing.

• Structural – structural fabric of buildings eg. Walls, foundations, floors, doors and windows, built-in fittings

• External – damage to all items external to buildings, eg. garages, sheds, yard, vehicles and other machinery.

Public sector infrastructure flood damages fall under the External Damages category but are usually assessed separately. This may include damage to utilities such as water and sewerage supply, gas, electricity and communications, and roads railway lines and associated structures. The type of structural damage sustained by a building depends upon both the materials and manner of its construction and the depth of inundation and velocity of the floodwaters. Inundation by deep, fast-flowing floodwaters may actually wash a building away, whereas shallow, slow moving water may cause relatively minor structural damage. The buildings exposed to potential flooding in South Leura are used for residential purposes. The materials and manner of their construction are variable, most are of brick or fibro while others are of timber cladding.


4.1.2 Indirect Damage

Tangible Indirect Damages are additional financial losses due to the disruption caused by flooding and are assessed in three broad cost categories: • Clean-up – this is generally the value of time spent by people in clean-up activities. They are

foregoing wages or other activities to remove flood debris and damaged items • Financial – actual expenses suffered by people or businesses due to loss of wages, sales and

production and alternative accommodation • Opportunity costs - non-provision of commercial and public services After a flood has subsided, there is a concentrated clean-up period. It is common for community minded people and organisations to rally as volunteers to help in the clean-up of flooded houses. Walls require washing down, both inside and out, in an attempt to reduce silt staining, silt is removed from the houses and irreparably damaged items are taken away for disposal. The cost of immediate post flood clean-up operations is essentially the value of the time of those engaged in the clean-up process plus the cost of removing and dumping flood damaged materials, together with loss of business for commercial establishments. A flood can severely disrupt the goods and services provided by commercial establishments in the community (this includes industrial and rural ventures). It may take many weeks for a community to regain their pre-flood levels of productivity. The indirect flood damage to the community includes the loss of production, revenue and wages, which occurs during the flood and the post-flood recuperative phase. Indirect damages also arise in a number of other ways. For example, the disruption and diversion of traffic, both during and immediately after a flood, represents another indirect loss.

4.2 Intangible Damages Intangible damages are usually social and environmental in nature and are difficult to quantify in monetary terms. Intangible damages can also be categorised into direct and indirect damages. • Direct – includes loss of memorabilia, pets, important documents and deaths, environmental

damage to flora and fauna, release of pollutants • Indirect – includes inconvenience and stress associated with the disruptions caused by flooding or

ill-health and trauma, may include loss of schooling and transport disruption. Most intangible damages are indirect and usually occur after the flood. Although intangible damages are difficult to quantify, they are usually given some consideration in the assessment of floodplain management options due to their significance to the community.

4.3 Actual and Potential Damages Damage estimates based on the costs arising from an actual flood event are referred to as actual flood damages. Potential damages are the maximum damages that could be incurred should such a flood occur. Actual damages are often less than potential damages due to actions taken to reduce flooding after flood warnings are issued. The data available for an actual damages study are in general more reliable than those used in a potential damages study. In the actual damage situation the areas, depths and duration of flooding and the number of properties inundated can usually be estimated reliably. Financial costs are more accurate when based on damage sustained during an actual event.


4.4 Estimation of Flood Damage Costs 4.4.1 Basis of Damage Estimates

For this Study, no actual broadscale flood damages figures were available for the area as there had been such a long period since major flooding occurred. Accordingly, potential flood damages were estimated.

This study estimates the potential flood damage likely to occur for both tangible direct and indirect damage. Section 4.5 provides estimates of potential Average Annual Damages (AAD) for each catchment to provide a basis for the relative assessment of the economic benefits of various proposed mitigation options. Intangible damages are considered qualitatively in Section 7.2.

Generally the data required to estimate potential direct flood damages includes the following:

• Land use/ Property type – residential, commercial/ slab on ground, elevated etc • Surveyed dwelling floor level and ground level – to determine depth of flooding above floor level

and above ground • Predicted flood levels for a range of ARIs – for this study 20, 50, 100 and PMF are used • Stage-damage relationships for actual or potential flood damage – curves or equations that relate

internal, structural and external damage to the depth of flooding above either floor levels or ground levels.

Indirect damages are frequently assumed to be a percentage of the direct damage costs. Commonly for residential properties indirect damages are assumed to be 15% of the direct damages.

Flood damage varies with land use. Land in the flood-prone areas of South Leura is used for a variety of purposes, such as residential, commercial, industrial and recreation (open space). Analysis has shown that damages to existing buildings and properties are restricted to residential areas. Although commercial and industrial properties are located within flood prone areas, there are no buildings located within the floodplain. As such the estimation of flood damages has involved calculating residential and infrastructure costs only. Currently, there are no strict guidelines regarding the estimation of flood damages in NSW and in particular no recommended damage curves for NSW. This is because damages can vary considerably from area to area, time to time, and even property to property. It is therefore difficult to determine site specific damages and consequently average values are typically applied. On this basis, a number of post flood damage surveys were reviewed for this study. The approach adopted for this study was based on relationships established from flood damages surveys undertaken after floods in Georges River 1986, Inverell in 1991 and Nyngan in 1990 by Water Studies. Adopted flood damages for up to a 2m depth of flooding were derived from the historical damage data, corrected for inflation and including GST. Details of the equations and parameters adopted are provided in Appendix F.

Flood damages were estimated for each ARI flood, then the average annual damage was calculated. Average Annual Potential Damage (AAD) is equal to the total damage caused by all floods over a long period of time divided by the number of years in that period and assumes that development is constant over the analysis period.1 It has been calculated using the total financial potential damages (direct and indirect costs) for a range of flood events and the probability of the event’s occurrence. Effectively, the AAD is the area under the curve when these two variables are graphed.

1 Floodplain Development Manual, NSW Government, April 2005


4.4.2 Residential

For residential properties, direct damage estimates represent the sum of the structural, contents and external cost components. The indirect damage estimates derived in this study are calculated as a clean-up cost and are related to the depth of property flooding above ground up to a maximum of $1,500. Due to the flash-flooding nature of the catchment it has been assumed that the financial cost and opportunity cost components of the indirect damages would be negligible. The equations used to calculate the potential damages are outlined in Appendix F. In addition, it was necessary to take account of community “flood awareness” and their experiences in coping with floods, that is, the higher the awareness and experience, the lower the ratio of potential damages to actual damages will be. Preparedness of a community is a function of both the turnover of the population and the time since the last flood. The higher the awareness and experience, the lower the ratio of potential damages to actual damages will be. A reduction factor is applied to reflect community flood awareness and flood warning procedures. Results from the social survey indicated that there is generally low level of flood awareness in the community and there is limited application or knowledge of flood warning and emergency procedures. In addition, it has been established that flooding in South Leura can be described as ‘flash flooding’, and as such there would be very limited time for residents to prepare against any potential flooding. Accordingly no reduction factor was applied in damage calculations.

4.4.3 Infrastructure / Public sector

A major component of infrastructure damage is concerned with transport – damages to roads, bridges and culverts and locally to rail and air connections where applicable. Other losses are to services such as water, sewage treatment plants, gas, electricity and telephones. The variability in terms of location, the period of inundation, problems of sedimentation and erosion are such that no standard technique is possible. Australian and international literature suggests that infrastructure damage is normally within the range of 7% to 20% of that to the private sector (DI Smith et al 1986). In this study, data on previous flood damage to roads was not available so the above estimate was adopted for damage to roads. Seven percent of the potential damages to the private sector was applied up to the 50 year ARI storm event, and ten percent for the 100 year ARI storm event and the PMF.

4.5 Estimated Average Annual Potential Damages Potential flood damages for existing conditions in South Leura to residential properties and infrastructure are given in Table 10. Separate values have been determined for each catchment. Damage estimates were originally undertaken in November 2006 (as per Appendix F). In Table 10, these estimates have been updated to represent February 2008 dollars, based on a 6.05% percentage increase in average weekly earnings, as recommended by the Department of Natural Resources (DNR). The AWE figures were obtained from the Bureau of Statistics website (www.abs.gov.au). These estimated damages assume that flood damages are fairly negligible in the 5 year ARI flood. Assuming a different ARI event for zero damages can significantly change the estimated AAD. A sensitivity analysis was undertaken to assess the impact of altering this assumption. The results are discussed in Section 4.5.1.


Table 10: Potential Flood Damages, Existing – Residential

Residential Infrastructure Flood Event (ARI)

Damage ($) Damage ($) Totals ($)

CATCHMENT A 20yr 67,940 4,756 72,697 50yr 71,629 5,014 76,643

100yr 73,788 7,379 81,167 Extreme 251,598 22,137 273,735

Average Annual Damage 10,664 856 11,520

CATCHMENT B 20yr 187,134 13,099 200,233 50yr 199,383 13,957 213,340

100yr 208,476 20,847 229,325 Extreme 356,236 62,543 418,779

Average Annual Damage 29,546 2,372 31,918

CATCHMENT C 20yr 102,469 7,173 109,642 50yr 114,550 8,018 122,568

100yr 122,243 12,224 134,466 Extreme 190,125 36,673 226,798


CATCHMENT D 20yr 12,223 856 13,079 50yr 12,816 897 13,713

100yr 13,250 1,325 14,576 Extreme 31,750 3,175 34925

Average Annual Damage 1,916 149 2,065

CATCHMENT E 20yr 51,891 3,632 55,523 50yr 55,186 3,863 59,049

100yr 58,886 5,888 64,775 Extreme 101,557 17,665 119,223


CATCHMENT F 20yr 78,666 5,506 84,173 50yr 86,915 6,084 92,999

100yr 98,206 9,820 108,027 Extreme 191,504 29,462 220,966



It should be noted that these estimates are potential damages and do not necessarily reflect actual damages that may occur during a flood. Community awareness and the actions of emergency services may significantly reduce the level of flood damage.

4.5.1 Sensitivity Analysis

A significant assumption in the estimation of AAD is the ARI event at which damages are zero. Initially, it was assumed that damages are negligible in the 5 year ARI design event and increase linearly up to the 20 year ARI event. Assuming a different ARI event for zero damages can significantly change the AAD. If damages are assumed to be zero in the 2 year ARI event, then estimated AAD for each catchment increases by factors between 1.6 and 1.8 from those documented in Table 9. Alternatively if damages are assumed to be zero in the 1 year ARI event, then estimated AAD for each catchment increases by factors between 3.2 and 3.4. Applying this same assumption to the AAD estimates for the mitigation options results in the financial benefits, ie. the reduction in AAD, increasing by roughly the same factors thereby increasing the benefit/cost ratios. The impact on the B/C ratio diminishes as the option capital cost increases. It was found that the AAD and B/C ratios are sensitive to the assumed event at which zero flood damage occurs. It is considered that zero damage in the catchment would probably occur between the 2 and 5 year ARI, but closer to the 5 year ARI, which approximately represents the estimated street drainage capacity in the catchment. Therefore the initial assumptions are considered reasonable and suitable for adoption for the purposes of this study.

4.6 Impacts of Floodplain Management Measures The full range of floodplain management measures are identified and assessed in Section 6. Those identified as appropriate for detailed investigation were considered further and their impacts, including any reduction in flood damages, are discussed in Section 7.


5.0 Existing Floodplain Management Measures

5.1 Existing Planning Policies Council does not have an existing flood policy however two relevant planning documents make reference to land subject to inundation and to stormwater management. These are described below.

5.1.1 LEP 2005

Council’s LEP 2005 has a section describing guidelines for development occurring on Land Subject to Inundation. The following is an extract from Part 3, Division 6, Clause 88. a) Consent shall not be granted to development on land that in the opinion of the consent authority

is subject to inundation unless the consent authority is satisfied that the proposed development would not: - Adversely impede the flow of flood waters on that land or on land in its immediate vicinity; or - Imperil the safety of persons on that land or on land in its immediate vicinity; or - Aggravate or be likely to result in erosion, siltation or the destruction of vegetation; or - Cause any adverse effect on the water table of the land or of the land in its immediate

vicinity. b) Nothing in this clause prevents the consent authority granting consent for the carrying out of

reasonable repairs to, renovation of, alterations to, extensions to, additions to or to a different use of, an existing building, if there will be no resulting increase in flood risk on the land concerned or on other land in its immediate vicinity.

c) The consent authority may, as a condition of consent, require: - The floor level of a building to be at a height sufficient, in its opinion, to prevent the flooding

or to reduce the incidence of flooding of that building or of adjoining land in its immediate vicinity; and

- Any portion of a building or structure below the height set in accordance with paragraph (a) to be built from flood compatible materials.

5.1.2 Blue Mountains Better Living DCP for Single Dwellings and Subdivsion Developments – Stormwater

The performance criterion in this DCP includes the following points of relevance to this study: • The development must not adversely alter the quantity of stormwater leaving the site; • Development is to maximise the potential for on site retention and use of stormwater runoff; • Subdivision must ensure that a site is available on each proposed allotment that is not inundated

during a flood of 100 year ARI storm event; and • Stormwater quality and quantity should be controlled at the source. The Floodplain Risk Management Plan for South Leura will take into account these two policies.


6.0 Management Options

6.1 Introduction The Floodplain Development Manual (April 2005) defines three ways of managing flood risk. These include property modification, response modification and flood modification. Examples of each are outlined in Table 11.

Table 11: Options for the Management of Flood Risk

Property Modification

• Zonings; • Voluntary purchase of high hazard properties; • House raising; • Flood proofing of buildings; • Flood access; and • Development Controls.

Response Modification

• Flood warning and effective warning time; • The protection and/or evacuation of an area; • The relief of evacuees; and • The recovery of the area once the flood subsides.

Flood Modification

• Flood Mitigation Dams; • Retarding basins; • Levees; • Bypass Floodways; • Channel Modifications; and • Floodgates.

An essential component of the above measures is asset management. The Council is responsible for ensuring adequate maintenance of drainage assets and floodplain risk management structures.

6.2 Key Issues • Flooding in South Leura can generally be described as ‘flash flooding’ • There have been a number of minor floods in recent years that have resulted in flooding of

properties, however no major flood events have been recorded in recent history and as such flood awareness is low.

• The flood hazard categories are predominantly high due to the steep nature of the channels and streams and the rapid rise of the flood waters.

• The land use in the catchment is predominantly residential, with a commercial centre and several resorts. The buildings impacted by flooding are generally residential.

• Flow in South Leura is predominantly conveyed by a mixture of natural channels, modified grass and concrete lined channels and culverts. In the upper areas of the catchments channels often run between houses, or along the backyards of properties. Many buildings are located in overland flow paths.


6.3 Community Input A key component in the assessment of the mitigation options and the development of the Floodplain Management Plan is community consultation. Gauging the community’s flood awareness and their opinions towards mitigation options is essential in developing a workable and successful plan. This has been achieved through a variety of measures as described in Section 2.4. It has been shown that the community’s flood awareness is relatively low, particularly in terms of larger floods. Therefore, increasing the community’s flood awareness is critical, and education programs have been recommended as part of the plan. The questionnaire sent out asked residents about potential development control. The results have shown that the majority of people believe that development should not be allowed on flood prone land or areas that pose a high hazard to people. Many responses also indicated that restrictions should be placed on new development, including ensuring that floor levels of new development are above estimated floor levels at the site. The proposed Local Floodplain Risk Management Policy covers these issues of development control and complements the overwhelming community feeling.

6.4 Input from Council’s Emergency Services Information regarding which roads are at risk of being flooded in the 100 year ARI storm event was provided to Council’s Emergency Management section to obtain recommendations on what roads need to remain open to allow access during flood events. The following list details the Council’s response: • Wilson, Govett St, Magdala St, Kanimbla St should remain trafficable as these roads provide the

access to a significant number of residential and commercial properties to the north; • Scott Ave should remain trafficable. Although there are alternate routes, the response times of

emergency services would be reduced. Scott Ave is a major access route into and out of Leura and is also a critical alternate route to the Great Western Highway; and

• Gladstone Road provides the only access to properties to the south and should remain open.

6.5 Property Modification Measures Property modification measures refer to modifications to existing development and/or development controls on property and community infrastructure for future developments. Measures are aimed at ensuring inappropriate development does not occur where there is a high risk of potential damage and to ensure that the risk to developments likely to be affected by flooding is minimised through minimum floor levels and flood proofing. The property modification measures considered are described below. An assessment for each option is included in Section 7.

6.5.1 Voluntary Purchase

The Floodplain Development Manual (April 2005) identifies that in certain areas of high hazard it may be impractical or uneconomic to provide structural mitigation measures to protect properties at high risk. In such cases voluntary purchase may be the most cost-effective way of reducing the hazard, with the area ultimately rezoned to a flood compatible use. Under such circumstances, property should be purchased at an equitable price and only where voluntarily offered. Such areas should ultimately be rezoned to a flood compatible use. Voluntary purchase was considered for those houses identified as being flooded over floor level in the 100 Year ARI and more frequent storm events. These houses included:


• 26 Abbey St - Option 14A • 12 Tennyson Ave - Option 22 • 4 Everglades Ave - Option 30 • 101 Gladstone Rd - Option 37A • 16 Scott Ave - Option 44 • 21 Scott Ave - Option 44A • 41-43 Sublime Point Rd - Option 61 • 31 Sublime Point Rd (refer section 6.7.5) - Option 60 Assessment of voluntary purchase schemes needs to take into consideration economic benefits, impacts on the local community and other special circumstances, for example heritage listed properties or heritage precincts. From the analysis conducted as part of this study only one property, 31 Sublime Point Rd, has been identified as a candidate for voluntary purchase consideration. Primarily there are no other feasible options that will effectively alleviate the flooding at this property. The flood issues affecting 31 Sublime Point Rd are discussed in more detail in Section 6.7.5. For the other properties, other mitigation options have been assessed as more appropriate. For more information on the assessment of each of the above properties refer to option numbers 14A, 22, 30, 37A, 44, 44A, 60 and 61 in Table 16.

6.5.2 House Raising

House raising can be a suitable management measure for houses in low hazard areas of the floodplain. Avoidance of flood damage by house raising achieves the following three important outcomes: • A reduction in personal loss; • A reduction in danger to personal safety and in the costs of servicing isolated people who remain

in their homes to protect possessions; and • A reduction in stress and post-flood trauma. Houses best suited to raising are timber framed and clad with non-masonry materials. Houses of single or double brick construction or slab-on-ground construction are generally either impossible or too expensive to raise, however the decision on this issue is site specific. As mentioned in the previous section there are 6 houses which have been identified as being below the 20 Year ARI flood level. The majority of these houses are of brick construction. The properties have been identified as being unsuitable for house raising, in terms of the associated costs. Alternative mitigation measures are considered more appropriate in each case.

6.5.3 Development Controls

As a result of this study, development within the identified floodplain can be more adequately regulated. Development controls will aim at reducing the risk of flooding and damage to properties. To this end, a draft local flood policy has been developed in the form of a combined draft Development Control Plan and a draft local approvals policy. The draft Local Flood Policy is included in Appendix G. It is understood from Council that the Draft Local Floodplain Risk Management Policy that has been developed will be incorporated by Council into the Blue Mountains Better Living DCP. Refer to option number 48 in Table 16 for a detailed assessment of this option.


6.5.4 Land Use Zoning Changes

In undeveloped areas where this flood study has shown that the land is subject to inundation, an appropriate step may be to change the zoning to a flood compatible use. It is proposed to finalise any recommendations for land use changes once the flood modification measures have been developed and agreed to by Council. Once this has been done a complete picture will be gained of the remaining areas that are at a significant risk of flooding. At this stage, areas that may be suitable for a zoning change include: • Area upstream of Megalong St culvert (currently zoned residential). Refer to option number 49 in Table 16 for a detailed assessment of this option.

6.5.5 Section 149 Certificates

A 149 Certificate is a planning certificate under Section 149 of the Environmental Planning and Assessment Act 1979 and is issued to future residents. Planning certificates give information on the development potential of a parcel of land including information on whether the land is affected by flooding. Advice is to be provided on Section 149(2) Certificates for properties affected by flooding in South Leura up to the 100 year ARI flood level. Council’s statutory responsibilities include updating S149 Certificates as new information becomes available. Section 149 (2) and Section 149 (5) Certificates are used to inform property owners, prospective property buyers and property developers of the flood risk associated with a particular allotment and that development may be restricted because of the likelihood of flooding or other risk. Refer to option number 51 in Table 16 for a detailed assessment of this option.

6.5.6 Flood Planning Level

The brief states that the selection of FPLs should be based on an understanding of flood behaviour, together with the balancing of the social, economic and environmental consequences of flooding, including the potential for property damage and risk to human life. In addition to flood behaviour, the Floodplain Development Manual (April 2005) identifies the issues shown in Table 12 as points of consideration in the selection of the FPLs. An assessment of each issue has been included in the table. It is recommended that the 1 in 100 year flood level be adopted as the Flood Planning Level for all land uses. A freeboard of 500mm is also recommended, resulting in an FPL of 1 in 100 year flood level + 500mm for South Leura. All levels at or below the FPL will be subject to specific land use and development controls. The FPL has been determined by balancing the need to minimise flood risk while not excessively restricting development and sterilising land.

Flood Planning Level = 1 in 100 year Flood Level + 500mm for all land uses Council should be aware that the nature of the catchment and its typically steep slopes combined with local effects such as landscaping will add to the variability of flood levels over time. As such it should be understood that the model results provided in this report indicate the level of risk of flooding rather than establish a definitive absolute inundation level.


Table 12: Assessment of Issues

Issue Assessment

Flood Behaviour Discussed in detail in Section 3. For the majority of the catchment, 20 year ARI storm will cause overtopping of roads and inundation of properties

Existing and Potential Land Use near or on the floodplain

The land adjacent to and on the floodplain in the majority of the upper reaches of the catchments is highly developed. There are some potential areas of future development. Generally though the undeveloped land adjacent to the creeks is typically steep and would be difficult to develop. As such the impact on potential development would be limited.

Current Flood Level used for Planning Purposes

Council does not have an existing FPL. However, the 1 in 100 year ARI storm event is the most common basis for an FPL.

Consequences of floods larger than the flood planning level

The Probable Maximum Flood is the largest possible flood. The PMF is not usually adopted as the FPL because of its low probability and the increased restriction on development that it poses.

Environmental Issues along the flood corridor

The land adjacent to and on the floodplain in the upper reaches of the catchments is highly developed and modified. The lower reaches are primarily zoned National Park. An appropriate FPL would provide an additional benefit in preventing development on the floodplain, thereby reducing further impacts on the waterways.

Flood warning, emergency response and Evacuation Issues

The flood warning time for the majority of the catchment is low, due to the steep nature of the streams and the small catchments. The FPL should prevent development occurring in the floodplain so as not to put any extra pressure on the SES.

Flood Readiness of the Community, both present and future

The flood readiness of the community is linked to the public’s flood awareness. Recent years have seen a number of small flood events in South Leura, so awareness of the risk of smaller floods is relatively high. However the awareness of residents affected by larger floods will be low. As such the FPL should be set at a higher level to ensure that a false sense of security is not created within the community is not created

Potential Impact of Future Development on Flooding

Potential future development has been considered and modelled as part of this study. Council’s development controls should ensure that future development minimises the impact on flood levels, by maintaining runoff levels from new development sites to pre-developed levels.

Duty of Care

Council has a duty of care to the community and will need to ensure that the final selection of the FPL minimises the risk to the community while not overly restricting the use of flood prone land.


The adoption of the proposed Flood Planning Level is included as Option 50 in Table 15.

6.6 Response Modification Measures 6.6.1 Flood Education and Awareness

A key component of minimising flood risk is ensuring a community is fully aware of the risks through flood education measures. Potential education strategies are listed below: • Section 149 Certificate; • Advice about flooding to residents (this could be in the form of a letter or newsletter sent out to

residents, etc); • Articles in local newspapers; • Public displays of flood photographs and newspaper articles in Council Chambers or shopping

centres; • Marking of signs or markers showing flood levels from previous significant flood events; and • Information of Council’s website. The community questionnaire that was distributed to residents questioned them about their knowledge of flooding in the area. Approximately 50% of replies indicated that they had no knowledge/information about flooding in the area. The incidence of large flood events is rare in South Leura and unless the community has had recent experience of these floods, residents understanding of the risks involved are diminished. Recent flood events in South Leura have been identified as smaller flood events, in the vicinity of 2 to 5 year ARI storm events. It can be assumed therefore that many residents will not be aware of the risk from larger floods. As such, raising community awareness through flood education is an ongoing process and will require a continuous effort by Council and the SES. It is recommended that Council develop a community awareness program, incorporating education strategies such as those outlines above. Refer to option 52 in Table 16 for the assessment of this option.


6.6.2 Flood Prediction and Warning

Flood prediction and warning is carried out by the Bureau of Meteorology and the SES. The effectiveness of flood prediction is diminished in the study area due to the small nature of the catchment, which is subject to short duration flash flooding difficult to predict. Floods will be caused by local thunderstorms where the warning time is likely to be short. The community questionnaire also confirmed this point, with no residents reporting that they have been warned prior to flooding in the area. The findings of this study, primarily the identification of hazardous areas and blocked roads will allow a better level of planning for the management of emergencies. It is recommended that Council provide the SES with flood information presented in this report so that they are able to update their emergency management plans as necessary. Refer to option number 53 in Table 16 for the detailed assessment.

6.7 Flood Modification Measures 6.7.1 Detention Basins

Detention basins provide temporary storage for floodwaters, thereby reducing the peak flow and reducing the size of a flood. In urban areas, basins are most suitable for small streams that respond quickly to rapidly rising floodwaters. The disadvantages of detention basins include: • They require a substantial area to achieve necessary storage; • There are associated safety issues for basins that have multi-purpose uses; • Long duration storms or multi-peak storms can result in overtopping of the basin, posing a safety

risk and a risk to property damage; and • Basins provide minimal attenuating effect when overtopping occurs. Basins were considered in several locations (where space and land zoning permitted) as a means of reducing peak storms. A number of locations potentially suitable for a basin have been assessed including: • Catchment A – western side of Govett St, upstream of culvert (option 6); • Catchment B – western side of Hartley Esplanade, in a Recreation Zone (option 16); • Catchment C – Golf Course upstream of Sub-Catchment C2 (option 35); • Catchment D – Golf Course (option 38); and • Catchment E – Upstream of 41-43 Sublime Point Rd (option 58). An analysis of each option is included in Table 16.

6.7.2 Levees

Levees are often considered an economically attractive measure to protect existing development in flood prone areas. The height or crest level of a levee is determined by a variety of factors that include: • The economics of the situation (including the nature of development requiring protection); • The physical limitations of the site; • The level to which floods can rise relative to the ground levels in the area (important in safety

considerations); and • The visual impact of the levee.


Levees were considered as an option to protect specific properties from flooding. The Floodplain Development Manual (April 2005) identifies the following major issues that should be considered when assessing the need for a levee. • Cost; • Flood Levels; • Visual impact; • Likelihood and consequence of damage and unacceptable personal danger levels if levee is

overtopped; and • Proper maintenance of the levee. Minor bunds were considered in a number of areas to protect specific properties. These locations have low lying houses or buildings close to existing channels. These include: • 37 Govett St (option 7); • 50 Govett St (option 8); • Abbey St (option 14); • 4 Everglades Ave (option 29); and • 9 Hester Place (option 47). An assessment of the proposed bunds is included in Table 16. A cost analysis has been included in Appendix H.

6.7.3 Channel Modifications

The creeks and streams part of the South Leura catchment can be generally characterised as steeper smaller streams with narrow floodplains. Channel modifications to smaller steeper streams are more likely to be effective in improving the hydraulic capacity of a channel. The potential disadvantages include: • By increasing the flow of floodwaters downstream, they can increase downstream flooding

problems; • Environmental impact on the creek habitat and ecology; • High cost of maintenance; and • Visual impact. Channel widening and deepening has been investigated in the areas listed in Table 13, and has been modelled fully in XP-SWMM. Rock lining (Rock mattress or stone pitched in cement mortar) will be required to minimise the risk of erosion. A full assessment of the channel modifications investigated is included in Table 16. A cost analysis has been included in Appendix H.


Table 13: Channel Modifications Considered

U/S Node

D/S Node Location Option

Number* Option

A1-2 A3-1 Wilson Street to Govett St 9 2m (W) x 1.5m (D), 1H:2V Sides

B2-9 B2-10 Megalong St to Craigend St (behind 26 Hartley Esp) 18 Widen to 2m

B2-11 B2-2 Megalong St to Craigend St (between 36 and 40-42 Craigend) 19 Widen to 2m

C1-2 C1-3 Lachlan Ave to Craigend St (east of Victoria St) 27 Erosion control and channel

improvements

C2-4 C2-8 Downstream of Gladstone Road (between numbers 101 and 103-105)

37 Channel Widening

F1-5 F1-2 Northern side of Morvan Road 42 Channel Widening

F1-6 F1-9 Channel running behind houses along Scott Ave (numbers 18 to 42) 45 Maintenance

E1-13 E1-14 Channel running through front yard of 41-43 Sublime Point Rd 56 Channel widening and pipe

upgrades

E1-1 E1-4 Pipe/channels collecting runoff from golf course, near 25 Sublime Point Rd

59 Channel widening and pipe upgrades

*Refer to Table 16 for assessment of option

6.7.4 Culvert Upgrades

Much of the flooding in Leura is a result of water backing up from undersized culverts and channels downstream. The upgrade of culverts in areas where this poses a high risk to both traffic and houses has been investigated and hydraulically modelled. A full list of culvert upgrades considered is included in Table 13. A preliminary cost estimate has been included in Appendix H. The assessment of the culvert options in shown in Table 16 in Section 7.

Table 14: Culvert Upgrades Considered

U/S Node


Number* Option

A1-1 A1-6 Corner of Kanimbla St and Wilson St 1 Culvert 2 No. x 1050mm dia RCP

A2-1 A2-4 Magdala St 2 Culvert 2 No. x 750 mm dia RCP A2-2 A2-3 Kanimbla St (east of Wilson St) 3 Culvert 2 No. x 900 mm dia RCP

A1-2 JA-1 Wilson St (south of Kanilba St) 4 Additional 2No. X 825 mm dia RCP

A3-1 JA-3 Govett St 5 Culvert 6 No. x 1050 mm dia RCP B1-1 B1-4 Craigend St (west of Abbey St) 11 Culvert 2 No. x 900 mm dia RCP B1-6 B1-10 Abbey St (south of Craigend). 12 Culvert 2 No. x 900 mm dia RCP B1-10 B1-8 Abbey St (south of Craigend). 13 Culvert 2 No. x 900 mm dia RCP B2-1 B2-4 Megalong St (east of Hartley Esp.) 15 Culvert 2 No. x 825 mm dia RCP

B2-4 B2-2 Megalong St to Craigend St (between Hartley Esp and Albert

17 Culvert 2 No. x 825 mm dia RCP


U/S Node


Number* Option

St, backs onto 24 Hartley Esp) B2-2 B2-5 Craigend St (east of Hartley Esp) 20 Culvert 2 No. x 1050 mm dia RCP

B2-5 B2-6 Craigend St and west side of Spencer St 21 Culvert 2 No. x 1200 mm dia RCP

C1-1 C1-2 Lachlan Ave (east of Victoria St) 26 Culvert 1 No. x 450 mm dia RCP

C1-3 C1-4 Craigend St (east of Everglades Ave) 28 Culvert 2 No. x 675 mm dia RCP

C1-5 C1-6 Corner of Northcote Road and Everglades Ave) 31 Culvert 2 No. x 825 mm dia RCP

C1-8 C1-10 Easter St (west of Everglades Ave) 32 Culvert 2 No. x 1050 mm dia RCP C1-9 C1-10 Easter St (west of Everglades Ave) 33 Culvert 1 No. x 600 mm dia RCP

C2-3 C2-4 Gladstone Rd (south of Wentworth Ave) 34 Culvert 4 No. x 450 mm dia RCP

C1-6 C1-7 Western side of Everglades from Northcote Rd to Easter St 36 Culvert 1 No. x 1200mm dia RCP

D-4 D-5 Southern side of Blaxland Rd, adjacent to 109 Gladstone Rd 39 Culvert 1 No. x 675 mm dia RCP

F1-12 F1-1 Southern side of Morvan Rd (east of Gladstone Road) 40 Culvert 1 No. x 1200 mm dia RCP

F1-1 F1-5 Morvan Rd (east of Gladstone Road) 41 Culvert 1 No. x 1200 mm dia RCP

F1-2 F1-6 22 Gladstone Road to 18-20 Scott Ave 43 Culvert 2 No. x 900 mm dia RCP

F1-9 F1-3 Scott Ave (east of Herbert St) 46 Culvert 3 No. X 900 mm dia RCP

E1-6 E1-17 Sublime Point Rd (extension of existing pipeline) 55 Culvert 1 No. x 900 mm dia RCP

E1-13 E1-14 Channel running through front yard of 41-43 Sublime Point Rd 56

Channel widening and pipe upgrades (3 No. x 600 mm dia RCP)

E1-12 E1-17

Sublime Point Rd. New collection pit at existing energy dissipation structure and then pipe along Sublime Point Rd, the run south of 49 Sublime Point Rd to outlet at E1-17

57 Culvert 1 No. x 1200mm dia RCP

E1-1 E1-4 Pipe/channels collecting runoff from golf course, near 25 Sublime Point Rd

59 Channel widening and pipe upgrades (1 No. x 675mm dia RCP)

*Refer to Table 16 for assessment of option


6.7.5 31 Sublime Point Road

In response to a number of storm events in January and February 2007 that resulted in above-floor flooding of 31 Sublime Point Road, Council requested that Maunsell review the flood management options for this property. The recent flood events have caused significant damage to the property. In addition to the economic costs, it is important to also appreciate the high level of emotional stress and anxiety that the owners suffer due to the frequency and risk of flooding. A management plan for this property needs to be developed and implemented by Council as soon as possible, to prevent further stress to the owners. Figure 1 shows that the house at 31 Sublime Point Road is located in the middle of the natural low point for an overland flow path through the property. The property receives overland flow from the north and also sheet flow from the back of the property to the west. In the past it has been reported that gutter flow from the road has also entered the property by overtopping the kerb. Road drainage was upgraded in 2006 in order to reduce this risk. The catchment analysis and modelling undertaken has indicated that the flooding problem is mainly related to the natural overland flow path running through the property. From the site visit undertaken with Council in March 2007, it was identified that water most likely pools at No. 29 and then once it reaches a sufficient height, overflows into 31 Sublime Point Rd. Landscaping and various features within the properties appear to have an influence on flow behaviour and flooding which may be exacerbating the problem by impeding flows.

Figure 1: Sublime Point Road

The following possible flood management options have been identified: a) Voluntary Purchase of No. 31 Sublime Point Road b) Upgrade the channel, pit and pipe located upstream at the golf course (option 59), to capture

more runoff from the golf course. Divert flow across the road and discharge at Nardin St. c) Undertake landscaping works on 29 and 31 Sublime Point Rd to redirect flows and allow it to exit

No. 31 more quickly with less impedence d) Flood proofing of 31 Sublime Point Road The associated advantages and disadvantages are listed in Table 15.


Table 15: Sublime Point Road – Flood Management Options

Option Advantages Disadvantages A Voluntary Purchase • Removes flood risk.

• Flooding has already caused significant damage to the property. This has resulted in significant emotional stress to the owners and made re-sale of the property more difficult.

• The Council could potentially re-develop and re-sell the property with a dwelling built higher up out of the flow path

• High cost • Social impact and

disturbance for existing owners who enjoy living at this location

B Upgrade the channel, pit and pipe located upstream at the golf course and No. 21 (option 59) and divert flow across Sublime Point Road to Nardin St

• Reduce risk of downstream flooding. Assuming no blockage, the flow could be reduced by up to 50% at No. 31.

• By diverting the flow to Nardin St, the risk of gutter flow entering No. 31 is reduced

• Council doesn’t have an easement in No. 21 Sublime Point Rd or Golf Course

• High Cost • If channels and pit are not

maintained, there is a high risk of blockage

• Discharge is to National Park. There is potential for erosion and environmental impacts

C Undertake landscaping work on 29 & 31 Sublime Point Rd to redirect flows and allow floodwaters to drain more quickly.

• Reduce hazard for No. 31 • May require purchase of land and/or creation of an easement

• Potentially would increase the hazard or affectation for No. 29,

• Potentially could increase road flooding, presenting a traffic hazard

• This option does not represent a long term solution

D Flood Proofing • May help to minimise damage in flood events

• Only a short term solution. • Difficult to achieve or

guarantee full protection Recommendations for Sublime Point Road Given the high cost of options A and B, it is recommended that options C and D be further considered by Council in the interim. Council will need to carefully consider the legal ramifications and the potential for increased liability that may result if they undertake the work. There may also be issues with achieving agreement with the various landowners. If options C and D are considered feasible by the Council, it should be recognised that they really only represent a short term solution which will not entirely remove the flood risk. Some flood risk will always remain because of the location of the dwelling in the low point of the property. Owners/occupants of No. 29 and 31 may in the future undertake other landscaping work, which may reduce the effectiveness of the work. Council should seriously consider voluntary purchase of the property as a medium to long term solution. The high initial cost could be offset by the resale or redevelopment of the property with the appropriate flood compatible development controls.


Voluntary purchase of 31 Sublime Point Road has been included in the assessment of options in Table 16. Local Real Estate agents were contacted to obtain an indication of property prices for the area. While median property prices in Leura are $452,000, prices are higher in South Leura. In particular, properties in the Sublime Point Road area generally have prices in the range between $600,000 to $1,000,000. Typical land value in Sublime Point Road is around $400,000 per lot (pers. comm. Ray White Leura) For 31 Sublime Point Road a property price of $800,000 was adopted. It is assumed that Council would then be able to demolish the dwelling and sell the vacant site reducing the net cost of this option to $400,000. Alternatively it may be feasible and more economical to undertake appropriate renovation works to the existing building such that some of the structure is retained but the habitable areas are relocated to higher ground at the rear and the front portion of the building removed to clear the flow path.


7.0 Assessment of Options The previous section outlined the types of management options considered. In this section the focus is on looking at each flood problem area and examining the options available to mitigate the flood risk. Initially a screening process was undertaken to shortlist options warranting further investigation including hydraulic modelling of the options, cost estimates, assessment of damages reduction and detailed assessment. Table 16 provides details of the long list of options initially considered and identifies which options were considered worthy of investigating in more detail. The detailed assessment of each option and the final recommendations made involved the consideration of the following factors: • Economic evaluation – the indicator adopted to rank options on economic merit is the benefit cost

ratio (BCR) • Non-economic evaluation:

- Hazard level, in terms of risk to life and to property; - Environmental and social impacts; and - Whether an evacuation route is affected and the impact on emergency management.

Table 17 summarises the evaluation of shortlisted options for each flood prone area in terms of economic considerations as well as a qualitative assessment of environmental, social and hazard factors. The advantages and disadvantages of each management option are considered and recommended option rankings are provided. For some of the shortlisted options, hydraulic analysis was not undertaken and therefore these options were not able to be given an economic rank. Some of these options are flagged for further investigation. Table 18 provides a summary of the separate economic and non-economic rankings while listing the recommended options in order of the resulting overall combined rank. The preliminary recommendations are presented in Figure 7.1 to 7.4 for all the sub catchments within South Leura.

7.1 Benefit Cost Analysis Estimates for the flood damages have been detailed in Section 4. Similarly, a flood damage analysis has been carried out for applicable mitigation options. Where a mitigation option was considered to warrant additional investigation, the option was modelled in SWMM and the results exported into the flood damages spreadsheet. This allowed the reduction in average annual damages to be determined and the economic benefit of each option to be assessed. The cost estimates of the upgrade components are detailed in Appendix H. It should be noted that all sizes for channels, culverts and bunds are preliminary only. A detailed survey would be necessary for the detailed design of all flood modification options that have been recommended. The results of the benefit cost analysis are included in Table 17. The economic savings were determined by calculating the difference between the average annual damages with and without the mitigation option, by applying an annual interest rate of 7% over 40 years. The benefit: cost ratio (BCR) was then determined. A full set of results is included in Appendix F.


Table 16: Screening of Floodplain Risk Management Options

U/S Node

D/S Node Location Flooding Issues Option

Number Option Existing

Size (culverts)

Advantages / Reduction in Risk Disadvantages / Impacts Shortlisted for further Consideration

Catchment A

A1-1 A1-6

Corner of Kanimbla St and Wilson St

Road not trafficable in 100 year ARI storm event

1 Culvert 2 No. x 1050 2 No. x 600

Provide access in the 100 year ARI storm event for all locations. Road is a critical access road and provides access to commercial and residential properties to the north.

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow. Risk of causing erosion and scouring at outlet

YES

A2-1 A2-4 Magdala St Road not trafficable in 100 year ARI storm event

2 Culvert 2 No. x 750

2 No. x 375, 450

Provide access in the 100 year ARI storm event for all locations

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow Risk of causing erosion and scouring at outlet

YES

A2-2 A2-3 Kanimbla St (east of Wilson St)

Road flooded in 100 year ARI storm event, remains trafficable

3 Culvert 2 No. x 900 1 No. x 450 Provide access in the 100 year ARI storm event

for all locations

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow. Road remains trafficable and alternate access is available Risk of causing erosion and scouring at outlet

YES

A1-2 JA-1 Wilson St (south of Kanilba St)


4 Additional 2 No. X 825 2 No. x 600

Provide access in the 100 year ARI storm event for all locations. Road provides access to commercial and residential properties to the north

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow May only provide limited benefit because upstream channels and pipes may have overflowed causing the road to be flooded.

YES


for all locations.

High Cost ($116,000), blockage risks. Risk of worsening flooding downstream by increasing flow. Risk of environmental damage through erosion and scouring. Erosion and sediment control required at outlet Downstream channel works would be needed, including erosion control High Tailwater means that proposed culverts would be ineffective. Although the road would be trafficable there would still be flooding.

NO While this road is a critical

access route, a new culvert is not viable.

Option 2 is preferable

6 Basin u/s of Govett St Culvert

N/A Peak flows could be controlled to minimise flooding downstream

Appears to be private land, land would have to be acquired. Due to large volume of flows and high tailwater downstream, the required basin size is large, may not be adequate space to minimise peak flow to an acceptable level

NO

7 Flood proofing and bund at 37 Govett St

N/A Divert flows from road to channel rather than to house

Visual Impact on house/backyard. May be safety issues. May cause flooding of adjacent properties YES

A3-1 JA-3 Govett St

Road flooded in 100 year ARI storm event, remains trafficable. The road provides access to commercial and residential properties to the north. Also houses at 37 and 50 Govett St flooded but not above floor level


N/A Divert flows from road to channel rather than to house Visual impact. May worsen road flooding YES

A1-2 A3-1 Wilson Street to Govett St

Existing channels cannot convey 100 year ARI flow. High hazard

9 2m (W) x 1.5m (D), 1H:1.5V Sides

N/A Reduction in flood liable land, increase in developable area

High Cost, risk of environmental damage to stream, possibility of increasing flow downstream. May require culvert upgrades downstream, unless there is adequate storage in channel.

YES

Catchment B

B1-1 B1-4 Craigend St (west of Abbey St)



1 No. x 450 Provide access in the 100 year ARI storm event for all locations

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow. Road is not major evacuation route, no properties isolated as a result of flooding

YES


U/S Node



Size (culverts)


12

Culvert 2 No. x 900 (B1-6 to B1-10)

1 No. x 750 Provide access in the 100 year ARI storm event for all locations. Prevent overland flow running into 26 Abbey St


YES

13

Culvert 2 No. x 900 (B1-10 to B1-8)

1 No. x 900 Provide access in the 100 year ARI storm event for all locations. Prevent overland flow running into 26 Abbey St

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow. Risk of causing erosion and scouring at outlet

YES

14 0.5m high bund in front of 22-26 Abbey St

N/A Overland flow prevented from running down driveways to houses

Visual impact. May worsen road flooding or affect adjacent houses. Safety issue of water ponding on road. YES

B1-6 B1-8 Abbey St (south of Craigend)

Road not trafficable in 100 year ARI storm event. Overland flow runs to 26 Abbey St. House flooded above floor level in 20 year ARI event High hazard

14A Voluntary Purchase of 26 Abbey St

N/A

The house at 26 Abbey St is located in the overland flow path. The hazard is high meaning there is a risk to life. Voluntary purchase of this property would take away this risk

Voluntary purchase is costly (>$500,000) and would potentially cause emotional stress to the property owner and/or occupants

NO


for all locations

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow. Road is still trafficable and alternate access to properties in the area is available

YES

B2-1 B2-4 Megalong St

(east of Hartley Esp.)


16

Basin upstream - in vacant land west of Hartley Esplanade

N/A Reduce downstream peak flows, thereby reducing flooding

Benefits reduced due to small size of catchment of basin. Also there is risk of environmental damage to the area NO

B2-4 B2-2

Megalong St to Craigend St (between Hartley Esplanade and Albert St, backs onto 24 Hartley Esp)

Channels and culverts run along the back of properties here and through front yards. Houses and other buildings are affected. In particular 175 Megalong St


Combination of open channels and 1 No. x 900

Prevent flooding of properties and associated buildings

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow. Location will be difficult to access due to nearby buildings, which will increase the cost.

YES

B2-9 B2-10

Megalong St to Craigend St (behind 26 Hartley Esp)

Channels and culverts run along the back of properties here and through front yards. Houses and other buildings are affected. High hazard

18 Widen to 2m N/A Reduction in flooded area, currently shed at risk.

High Cost, risk of environmental damage to stream, possibility of increasing flow downstream. May not be sufficient room for bigger channel. Safety issue of large channel in front yard. Visual impact.

YES

B2-11 B2-2

Megalong St to Craigend St (between 36 and 40-42 Craigend)

Channels and culverts run along the back of properties here and through front yards. Houses and other buildings are affected. In particular 40-42 Craigend St. High hazard

19 Widen to 2m N/A Reduction in flood inundation area, garage in floodpath

High Cost, risk of environmental damage to stream, possibility of increasing flow downstream. May not be sufficient room for bigger channel. Safety issue of large channel in front yard. Visual impact.

YES


U/S Node



Size (culverts)


B2-2 B2-5

Craigend St (east of Hartley Esplanade)

Road not trafficable in 100 year ARI storm event High Hazard Properties along Spencer St affected by overland flow

20 Culvert 2 No. x 1.05 1 No. x 900

Provide access in the 100 year ARI storm event for all locations High

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow. Alternate access to properties in this area is available

YES

21 Culvert 2 No. x 1.2 1 No. x 750

Prevent overland flow from flooding properties, including 12 Tennyson Avenue and 7 Spencer St. Erosion and scour protection works would be required at the outlet at B2-6

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow Risk of causing erosion and scouring at outlet

YES

22 Voluntary Purchase of 12 Tennyson

N/A

The house at 12 Tennyson is located in the overland flow path and is at a low point. All overland flow will be directed to the house. The hazard is high meaning there is a risk to life. Voluntary purchase of this property would take away this risk.

Voluntary purchase is costly and would potentially cause emotional stress to the property owner and/or occupants. NO

23 Flood Proofing of 12 Tennyson Ave

N/A A bund and channel works could direct overland flow away around the property and away from the house

This option does not reduce the risk to life, only the hazard to the house NO

B2-5 B2-6

Craigend St and west side of Spencer St

Current system inadequate to take the 100 year ARI flow. 12 Tennyson Ave flooded above floor level in 100 year ARI event and house at 7 Spencer St flooded but not above floor level. High hazard flowpath through property at 12 Tennyson Ave.

24 Flood Proofing of 7 Spencer

N/A

A bund and channel works would direct any overland flow away from this property towards 12 Tennyson Ave. The flow to 12 Tennyson Ave would not increase as the flow runs to the property regardless

This option would need to be combined with the voluntary purchase of 12 Tennyson Ave NO

Catchment C

C1-1 C1-2 Lachlan Ave (east of Victoria St)


26 Culvert 1 No. x 0.45 1No. x 300 Provide access in the 100 year ARI storm event

for all locations

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow. Road is still trafficable and alternate access is available Risk of causing erosion and scouring at outlet

YES

C1-2 C1-3

Lachlan Ave to Craigend St (east of Victoria St)

7 and 9 Lachlan Ave at risk of flooding. Severe erosion risk due to high channel slope Also channel reduces in size at Craigend St. Discharge into pit needs to be improved. In large storm events water will flow directly across road.

27

Erosion control and channel improvements

N/A

Reduce flood risk to 7 and 9 Lachlan Ave. Erosion control works will minimise erosion in the future, and reduce environmental damage during storms Reduce the volume of floodwaters running across Craigend St.

High Cost, risk of environmental damage to stream, possibility of increasing flow downstream YES

C1-3 C1-4

Craigend St (east of Everglades Ave)



for all locations

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow. Road is still trafficable and alternate access is available

YES


U/S Node



Size (culverts)


29 1m high bund and flood proofing

N/A Direct benefit to 4 Everglades Ave by diverting flood waters away from house

Visual Impact on house/backyard. The hazard to the house may be reduced but there will still be high hazard flow running through the property, presenting a risk to life. May also require channel re-alignment.

YES

C1-4 C1-5 4 Everglades Ave

House is flooded above floor level in 20 year ARI storm event

30 Voluntary Purchase N/A

The house at 4 Everglades Ave is located adjacent to the channel and is in the flood prone area. The hazard is high meaning there is a risk to life. Voluntary purchase of this property would take away this risk.


C1-5 C1-6

Corner of Northcote Road and Everglades Ave)


31 Culvert 2 No. x 825 1No. x 600 Provide access in the 100 year ARI storm event

for all locations

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow. Alternate access is available Risk of causing erosion and scouring at outlet

YES

C1-8 C1-10

Easter St (west of Everglades Ave)



for all locations


YES

C1-9 C1-10

Easter St (west of Everglades Ave)



for all locations


YES

34 Culvert 4 No. x 450 2No. x 450

Provide access in the 100 year ARI storm event for all locations. Although still trafficable, road provides only access to properties to the south, so flooding should be prevented.

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow. Road is still trafficable and alternate access is available

YES

C2-1 C2-4

Gladstone Rd (south of Wentworth Ave)

Road flooded in 100 year ARI storm event, remains trafficable. Road provides only access to properties to the south 35

Detention Basin located at Golf Course upstream of sub-catchment C2

N/A

Potential to reduce peak flows, thereby reducing flood risk downstream. Specifically, the risk of flooding of Gladstone Road could be reduced. Could become a feature of the golf course and/or be utilised in a water re-use scheme for the golf course

Negotiation would be required with golf course operators. YES

C1-6 C1-7

Western side of Everglades Ave from Northcote Road to Easter St

Currently there is no channel to convey flow here, it appears to have silted up. Flow will run onto road and adjacent properties. Barn on corner of Easter St and Everglades Ave is flooded

36 Culvert 1 No. x 1200mm dia RCP

N/A Reduce overland flow on road, reduce flood risk to barn High Cost, possibility of increasing flow downstream YES

C2-4 C2-8 Downstream of Gladstone Rd (between 101 and 103-

House at 101 Gladstone is flooded above floor level in the 100 year ARI storm

37 Channel widening Varies

By increasing the channel capacity to convey the 100 year ARI flow, there will be a direct benefit to 101 Gladstone Rd, by reducing the risk of over-floor flooding

High cost, risk of environmental damage to stream, possibility of increasing flow downstream. YES


U/S Node



Size (culverts)


105 Gladstone)

event

37A

Voluntary Purchase of 101 Gladstone Rd

N/A

The house at 101 Gladstone is located adjacent to the creek and is in the flood prone area. The hazard is high meaning there is a risk to life. Voluntary purchase of this property would take away this risk.


Catchment D

D-1

Catchment D - Gladstone Road and Blaxland Ave

Roads downstream flooded, though still trafficable

38

Basin upstream - in vacant land west of Hartley Esplanade

N/A Reduce downstream peak flows, thereby reducing flooding

Benefits reduced due to small size of catchment of basin. Also there is risk of environmental damage to the area NO

D-4 D-5

Southern side of Blaxland Rd, adjacent to 109 Gladstone Rd

Existing channel has a small capacity and will not convey the 100 year ARI flow. Yard and house at 109 Gladstone at risk


Existing channel Reduce the risk to 109 Gladstone Road High Cost, blockage risks. Risk of worsening flooding

downstream by increasing flow. YES

Catchment F

F1-12 F1-1

Southern side of Morvan Rd (east of Gladstone Road)

Ponding of water at pit in front of 3 Morvan Road, with potential to spill to Morvan Road

40 Culvert 1 No. x 1.2 1No. x 525 Prevent ponding of floodwaters High Cost, blockage risks. Risk of worsening flooding

downstream by increasing flow YES

F1-1 F1-5

Morvan Rd (east of Gladstone Road)



for all locations

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow. Benefits reduced because road is still trafficable and alternate access is available

YES

F1-5 F1-2 Northern side of Morvan Road

Existing channel cannot convey 100 year ARI flow

42 Channel Widening N/A Reduction in flooded area High Cost, risk of environmental damage to stream,

possibility of increasing flow downstream YES

43 Culvert 2 No. x 0.9 1No. x 600

Provide access in the 100 year ARI storm event for all locations. Scott Ave is a critical access route

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow. Difficulties in gaining access to pipe running between 21 Scott Ave and 15 Scott Ave

YES Scott Ave is a critical

access route.

44 Voluntary purchase of 16 Scott Ave

N/A

The house at 16 Scott Ave is located in the overland flow path. The hazard is high meaning there is a risk to life. Voluntary purchase of this property would take away this risk.

Voluntary purchase is costly and would potentially cause emotional stress to the property owner and/or occupants. NO F1-2 F1-6

22 Gladstone Road to 18-20 Scott Ave

Road not trafficable in 100 year ARI storm event Houses at 16 and 21 Scott Ave is affected by overland flow and flooded above floor level for 20 year ARI event

44A Voluntary purchase of 21 Scott Ave

N/A

The house at 21 Scott Ave is adjacent to an overland flow path. The hazard is high meaning there is a risk to life. Voluntary purchase of this property would take away this risk.



U/S Node



Size (culverts)


F1-6 F1-9

Channel running behind houses along Scott Ave (numbers 18 to 42)

Existing channel cannot convey 100 year ARI flow

High hazard

45 Maintenance N/A Reduction in flood risk by regular maintenance. Maintenance including weed removal could provide environmental benefits

High Cost, risk of environmental damage to stream, possibility of increasing flow downstream YES

F1-9 F1-3 Scott Ave (east of Herbert St)


46 Culvert 3 No. X 900 Various

Provide access in the 100 year ARI storm event for all locations. Scott Ave is a critical access route

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow

YES

Scott Ave is a critical access route

F2-1 F1-4/F2-2

9 Hester Place

Garage/Shed is affected on this property

47 1m high bund - Ensure garage and house is not affected. Hazard

is high Visual Impact on house/backyard. May be safety issues YES

General Management Options

48

Incorporate Draft Local Floodplain Risk Management Policy in Blue Mountains Better Living DCP

N/A

Councils adoption of the policy will aid in making the community aware of the extent and degree of hazard of flood prone lane, define the flood planning levels, reduce the risk and damage to existing areas of development and ensure that future land use and development is compatible with flood risk

May reduce the amount of land available for development, which will impact landowners YES

49 Land Zoning Changes N/A

Zoning changes to flood prone land that has not been developed can ensure that future land use and development is compatible with flood risk

May reduce the amount of land available for development, which will impact landowners YES

50

Adopt 100 Year ARI flood level + 500mm as flood planning level for all land uses

N/A

FPL's help to define where development control measures are required and to define design levels for mitigation works to manage existing flood risk

The FPL does not address personal danger issues and need to be combined with effect emergency response planning and land use restrictions

YES

51 Section 149 Certificates N/A

Enables Council to provide information to prospective purchasers on whether there are flood related development controls on their land

Limited circulation, generally do not reach the majority of property owners and occupants, since they are typically triggered by property sale

YES

52

Council to implement a Flood Education and Awareness program

N/A Reduction in loss or damage to possessions as a result of flooding

Needs to be ongoing to maintain awareness of hazard, and new residents would need to be informed. The short warning times for flooding minimises the preparedness of residents

YES

N/A N/A South Leura OVERALL

53

Council to present SES with flooding information presented in this report

N/A

SES will be able to incorporate the outcomes of the flood study into their emergency management plans and as such response to emergencies will be improved

Benefits are reduced due to short flood warning times and possible flooding of main access route YES

Catchment E


U/S Node



Size (culverts)


E1-6 E1-17 Sublime Point Road

House at 41-43 Sublime Point Rd is flooded in the 20 year ARI storm event. The flood risk has been increased by the recent installation of the new drainage pipe along Sublime Point Rd. Flow is now concentrated at this point

55

Extend 900mm dia pipe along Sublime Point Rd. Outlet at E1-16.

N/A Pipe flow diverted away from 41-43 Sublime Point Road

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow YES

E1-13 E1-14 41-43 Sublime Point Rd


56

Upgrade channels and pipelines running through 41-43 to convey 100 year ARI flow

Varies Reduce risk of flooding to 41-43 Sublime Point Rd High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow. Visual impact, safety risk of open channel running through property.

NO

E1-12 E1-16 Sublime Point Road


57

Install stormwater pit at E1-12 and divert all upstream flow via 1200mm dia pipe to E1-16 along Sublime Point Rd

N/A All flow upstream currently discharged to 41-43 Sublime Point Rd. High risk of flooding and high hazard.

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow YES

E1-12 Sublime Point Rd


58

Install on-site detention to decrease peak flow downstream

N/A By decreasing peak flow, the risk to 41-43 Sublime Point Rd is significantly reduced

The volume required is very large and there is inadequate space to locate a detention structure. NO

E1-1 E1-4 Sublime Point Rd

Overland flow from golf course runs to properties 21 to 35-39 Sublime Point Rd. 31 Sublime Point Rd flooded above floor level in 100 year ARI storm

59

Install new pit and upgrade pipe to 1 x 675mm dia. Upgrade channels

1 No. x 300 Reduce overland flow from golf course running through properties

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow. YES

E1-10 E1-10B

31 Sublime Point Rd

House flooded above floor level in 20 year ARI storm

60 Voluntary purchase of 31 Sublime Point Rd

N/A The house at 31 Sublime Point Rd is located in an overland flow path. Voluntary purchase of this property would take away this risk.

Voluntary purchase is costly and would potentially cause emotional stress to the property owner and/or occupants.

YES No other viable options


U/S Node



Size (culverts)


E1-13 E1-14 41-43 Sublime Point Rd

House flooded above floor level in 20 year ARI storm

61

Voluntary purchase of 41-43 Sublime Point Rd

N/A The channel here runs through the front yard of 41-43 Sublime Point Rd. Voluntary purchase of this property would take away this risk.


* Preliminary sizing of culverts, channels and bunds only


Table 17: Assessment of Shortlisted Floodplain Risk Management Options

Option Number Description Cost

Estimate BCR Economic

Rank Environmental impact Social impact Hazard category Evacuation routes/access

Non-economic

Rank Overall Rank

Catchment A

1 Culvert upgrade - corner of Kanimbla St and Wilson St

$98,000 0.22 8 Risk of causing erosion and scouring at outlet (Erosion and sediment control required at outlet)

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow.

Low

Provide access in the 100 year ARI storm event for all locations. Road is a critical access road

and provides access to commercial and residential properties to the north.

8

6

2 Culvert upgrade - Magdala St $58,000 0.13

13

Risk of causing erosion and scouring at outlet

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow

High Provide access in the 100 year ARI storm event for all locations. This will provide access to Govett St and Clarence St.

11 13

3 Culvert upgrade - Kanimbla St (east of Wilson St)

$57,000 -

Risk of causing erosion and scouring at

outlet High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow. Low

Provide access in the 100 year ARI storm event for all locations, however, not critical as road remains trafficable and alternate access is available

Not Recommended

4 Culvert upgrade - Wilson St (south of Kanilba St)

$ 62,000 -

Nil

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow May only provide limited benefit because upstream channels and pipes may have overflowed causing the road to be flooded.

High

Provide access in the 100 year ARI storm event for all locations. Road provides access to

commercial and residential properties to the north but alternative access is available

Not Recommended


$24,000 0.14 12 Nil

Divert flows from road to channel rather than to house Visual Impact on house/backyard. May be safety issues. May cause flooding of adjacent properties. The impacts of a bund on adjacent property and its feasibility need to be assessed

High Nil 21 18


$24,000 0.70 4 Nil

Divert flows from road to channel rather than to house Visual impact. May worsen road flooding. The impacts of a bund on adjacent property and its feasibility need to be assessed

High Nil 15 11

9 Channel modifications – Wilson Street to Govett St

$81,000 0.26 7

Risk of environmental damage to stream, possibility of increasing flow downstream.

Reduction in flood liable land, increase in developable area High Cost. May require culvert upgrades downstream, unless there is adequate storage in channel.

High Nil 17 15

Catchment B

11 Culvert upgrade – Craigend St (west of Abbey St)

$72,000 -

Nil


Low Provide access in the 100 year ARI storm event for all locations, however, alternative access is

available to nearby properties Not Recommended





Non-economic

Rank Overall Rank

12 Culvert upgrade – Abbey St (south of Craigend)

$84,000

13 Culvert upgrade - Abbey St (south of Craigend)

$150,000

0.16 10 Risk of causing erosion and scouring at outlet

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow. Prevent overland flow running into 26 Abbey St

High

Provide access in the 100 year ARI storm event for all locations. Road is not major evacuation route, no properties isolated as a result of flooding

9 10

14 0.5m high bund in front of 22-26 Abbey St

$24,000 0.32 5 Nil

Overland flow prevented from running down driveways to houses Visual impact. May worsen road flooding or affect adjacent houses. Safety issue of water ponding on road.

High Nil 13 9

15 Culvert upgrade - Megalong St (east

of Hartley Esp.) $65,000 -

Nil High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow. High

Provide access in the 100 year ARI storm event for all locations, however, alternative access

available. Not Recommended

17

Culvert upgrade - Megalong St to Craigend St (between Hartley Esplanade and Albert St, backs onto 24 Hartley Esp)

$254,000 0.16 11 Nil

Prevent flooding of properties and associated buildings Blockage risks. Risk of worsening flooding downstream by increasing flow. Location will be difficult to access due to nearby buildings, which will increase the cost.

High Nil 14 16

18

Channel widening - Megalong St to Craigend St (behind 26 Hartley Esp)

$32,000 -


Reduction in flooded area, currently shed at risk. May not be sufficient room for bigger channel. Safety issue of large channel in front yard. Visual impact.

High Nil Not Recommended

19

Channel widening - Megalong St to Craigend St (between 36 and 40-42 Craigend)

$50,000 -


Reduction in flood inundation area, garage in floodpath High Cost, May not be sufficient room for bigger channel. Safety issue of large channel in front yard. Visual impact.

High Nil Not Recommended





Non-economic

Rank Overall Rank

20 Culvert upgrade - Craigend St (east of Hartley Esplanade)

$72,000

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow. Although alternate access is available, overland flow from the road runs towards houses along Spencer St.

High

21 Culvert upgrade - Craigend St and west side of Spencer St

$390,000

0.10 16


Prevent overland flow from flooding properties, including 12 Tennyson Avenue and 7 Spencer St. Erosion and scour protection works would be required at the outlet at B2-6 This option is preferable to 22, 23 and 24 because it removes the risk to life and the hazard to properties. It also minimises the social impact

High

Provide access in the 100 year ARI storm event for all locations, however, alternate access to properties in this area is available

2 7

Catchment C

26 Culvert upgrade - Lachlan Ave (east of Victoria St)

$38,000 - Risk of causing erosion and scouring at


Provide access in the 100 year ARI storm event for all locations, however, road is still trafficable

and alternative access is available Not Recommended

27

Channel improvements - Lachlan Ave to Craigend St (east of Victoria St)

$40,000 -

High Cost, risk of environmental damage to stream Erosion control works will minimise erosion in the future, and reduce environmental damage during storms

Reduce flood risk to 7 and 9 Lachlan Ave. Reduce the volume of floodwaters running across Craigend St. Possibility of increasing flow downstream

High Nil 18 19

28 Culvert upgrade - Craigend St (east of Everglades Ave)

$48,000 -

Nil High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow. Low


and alternative access is available Not Recommended

29 1m high bund and flood proofing - 4 Everglades Ave

$33,000 1.85

1 May also require channel re-alignment.

Direct benefit to 4 Everglades Ave by diverting flood waters away from house Visual Impact on house/backyard. The hazard to the house may be reduced but there will still be high hazard flow running through the property, presenting a risk to life.

Low Nil 3 1

31 Culvert upgrade - Corner of Northcote Road and Everglades Ave)

$85,000 -


High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow. High

Provide access in the 100 year ARI storm event for all locations, however, alternate access is

available Not Recommended

32 Culvert upgrade - Easter St (west of Everglades Ave)




and alternate access is available Not Recommended

33 Culvert upgrade - Easter St (west of Everglades Ave)





34 Culvert upgrade - Gladstone Rd (south of Wentworth Ave)

$56,000 0.2 9 Nil High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow. Low

Provide access in the 100 year ARI storm event for all locations. Although still trafficable, road

provides only access to properties to the south, so flooding should be prevented.

16 17





Non-economic

Rank Overall Rank

35 Detention basin – Golf Course upstream of sub-catchment C2

Not Costed -

Could become a feature of the golf course and/or be utilised in a water re-use scheme for the golf course

Potential to reduce peak flows, thereby reducing flood risk downstream. Specifically, the risk of flooding of Gladstone Road could be reduced. Negotiation would be required with golf course operators.

Low Nil 6 4

36

Culvert upgrade - Western side of Everglades Ave from Northcote Road to Easter St

$124,000 0.08 17 Nil

Reduce overland flow on road, reduce flood risk to barn

High Cost, possibility of increasing flow downstream

High Nil 20 20

37

Channel widening - Downstream of Gladstone Rd (between 101 and 103-105 Gladstone)

$42,000 0.98 3 Risk of environmental damage to stream

By increasing the channel capacity to convey the 100 year ARI flow, there will be a direct benefit to 101 Gladstone Rd, by reducing the risk of over-floor flooding

High cost, possibility of increasing flow downstream.

Low Nil 10 5

Catchment D

39

Culvert upgrade - Southern side of Blaxland Rd, adjacent to 109 Gladstone Rd

$43,000 0.001 20 Nil Reduce the risk to 109 Gladstone Road

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow.

Low Nil Not Recommended

Catchment F

40

Culvert upgrade - Southern side of Morven Rd (east of Gladstone Road)

$50,000 - Nil Prevent ponding of floodwaters High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow

Low - Not Recommended

41 Culvert upgrade - Morven Rd (east of Gladstone Road)

$52,000 - Nil High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow. Low



42 Channel widening - Northern side of Morvan Road

$35,000 - Risk of environmental damage to stream

Reduction in flooded area. High Cost, possibility of increasing flow downstream

Low Nil Not Recommended

43 Culvert upgrade - 22 Gladstone Road to 18-20 Scott Ave

$267,000 0.31 6 Nil

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow. Difficulties in gaining access to pipe running between 21 Scott Ave and 15 Scott Ave

Low/High Provide access in the 100 year ARI storm event

for all locations. Scott Ave is a critical access route

1 2

45

Maintenance - Channel running behind houses along Scott Ave (numbers 18 to 42)

$103,000 -

Risk of environmental damage to stream

Maintenance including weed removal could provide environmental benefits

Reduction in flood risk by regular maintenance.

High Cost, possibility of increasing flow downstream

High Nil 19 21

46 Culvert upgrade - Scott Ave (east of Herbert St)

$164,000 - Provide access in the 100 year ARI

storm event for all locations. Scott Ave is a critical access route

High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow High

Provide access in the 100 year ARI storm event for all locations. Scott Ave is a critical access

route 12 14





Non-economic

Rank Overall Rank

47 1m high bund - 9 Hester Place $33,000 1.04 2 Nil

Ensure garage and house is not affected. Visual Impact on house/backyard. May be safety issues

High Nil 5 3

General Management Options

48

Incorporate Draft Local Floodplain Risk Management Policy in Blue Mountains Better Living DCP

Not Costed -

-

Councils adoption of the policy will aid in making the community aware of the extent and degree of hazard of flood prone lane, define the flood planning levels, reduce the risk and damage to existing areas of development and ensure that future land use and development is compatible with flood risk May reduce the amount of land available for development, which will impact landowners

N/A - Recommended for implementation

49 Land Zoning Changes

Not Costed -

-

Zoning changes to flood prone land that has not been developed can ensure that future land use and development is compatible with flood risk May reduce the amount of land available for development, which will impact landowners


50

Adopt 100 Year ARI flood level + 500mm as flood planning level for all land uses

Not Costed -

-

FPL's help to define where development control measures are required and to define design levels for mitigation works to manage existing flood risk

N/A

The FPL does not address personal danger issues and need to be combined with effect emergency response planning and land use

restrictions

Recommended for implementation

51 Section 149 Certificates

Not Costed -

-

Enables Council to provide information to prospective purchasers on whether there are flood related development controls on their land


52

Council to implement a Flood Education and Awareness program

Not Costed -

-

Reduction in loss or damage to possessions as a result of flooding Needs to be ongoing to maintain awareness of hazard, and new residents would need to be informed.

N/A The short warning times for flooding minimises the preparedness of residents


53

Council to present SES with flooding information presented in this report

Not Costed -

- Benefits are reduced due to short flood warning times and possible flooding of main access route

N/A

SES will be able to incorporate the outcomes of the flood study into their emergency management plans and as such response to emergencies will

be improved


Catchment E

55

Extend 900mm dia pipe along Sublime Point Rd. Outlet at E1-16

$190,000 0.03 19 Nil

Pipe flow diverted away from 41-43 Sublime Point Road High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow

High 0.03 Not Recommended

57

Install pit at E1-12 and divert upstream flow via 1200mm dia pipe to E1-16 along Sublime Point Rd

$205,000 0.11 15 Nil

Reduced risk of flooding to House at 41-43 Sublime Point Rd High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow

High Nil 7 12





Non-economic

Rank Overall Rank

59

Install pit and upgrade pipe to 675mm dia. Upgrade channels - Sublime Point Rd

$76,000 0.07 18 Nil

Reduce overland flow from golf course running through properties High Cost, blockage risks. Risk of worsening flooding downstream by increasing flow.

Low Nil 22 22

60 Voluntary purchase - 31 Sublime Point Rd

$400,000 0.13 14 Nil

The house at 31 Sublime Point Rd is located in an overland flow path. Voluntary purchase of this property would take away this risk. Voluntary purchase is costly and would potentially cause emotional stress to the property owner and/or occupants.

Low Nil 4 8


Table 18: Summary of Option Ranking

Option BCR Economic Rank

Non-economic

Rank

Average Overall Rank

Main reasons for recommendation

29 1.85 1 3 2 1 Highest economic benefit, social benefit


43 0.31 6 1 3.5 2 Critical access route, high economic benefit

47 1.04 2 5 3.5 3 Low cost, social benefit

35 6 6 4 Potential risk reduction and environmental benefits


37 0.98 3 10 6.5 5 High economic benefit, social benefit

Not required if option 35 feasible


20, 21 0.1 16 2 9 7 Hazard reduction, high economic benefit

60 0.13 14 4 9 8 High social and economic benefit

14 0.32 5 13 9 9 Low cost, social benefit


12, 13 0.16 10 9 9.5 10 Improved access, high social benefit


57 0.11 15 7 11 12 Risk reduction, social benefit


46 12 12 14 Critical access route

9 0.26 7 17 12 15 Economic benefit

Not recommended if option 7 and 8 feasible

17 0.16 11 14 12.5 16 Economic benefit

34 0.2 9 16 12.5 17 Improved access, low priority


27 18 18 19 Risk reduction

36 0.08 17 20 18.5 20 Low priority

45 19 19 21 Environmental benefit, low priority

59 0.07 18 22 20 22 Not recommended


8.0 Floodplain Management Plan 8.1 Floodplain Management Plan Under the NSW Government’s Floodplain Management Manual, the primary objectives for a Floodplain Risk Management Plan are: • To reduce the social and economic impact of flooding on individual owners and occupiers of flood

prone property; and • To reduce private and public losses resulting from floods. Council has a duty of care in advising property owners, occupiers and developers on the extent and level of flooding and in making decision with regard to floodplain risk management. Some of the benefits gained by the existing flood affected community and residents from undertaking the recommended management actions include: • A reduction in average annual damages (whether by the reduced occurrence and extent of over

floor flooding; the reduced number of dwellings incurring above floor flooding; the reduced number of flooded allotments; and/or the reduced number of overall dwellings affected by flooding);

• A reduction in flood hazard levels; • A reduction in adverse social impacts (including improved community protection in major floods); • Improved protection of community infrastructure and essential services; and • Improved community responses to flood risk management (including better evacuation

management, better flood awareness/warning). A preliminary plan has been developed and is shown in Table 19 below. The Plan will be further developed in consultation with Council and relevant stakeholders.

Table 19: South Leura Floodplain Risk Management Plan



Property Modification Measures

48 Incorporate Draft Local Floodplain Risk Management Policy in Blue Mountains Better Living DCP

N/A - - High

49 Land Zoning Changes N/A - - High

50 Adopt 100 Year ARI flood level + 500mm as the flood planning level N/A - - High

51 Section 149 Certificates N/A - - High

60 Voluntary purchase of 31 Sublime Point Rd 400,000 0.13 8 Medium

Response Modification Measures

52 Council to implement a Flood Education and Awareness program N/A - - High

53 Council to present SES with flooding information presented in this report N/A - - High

Flood Modification Measures Culvert Upgrades

1 Corner of Kanimbla St and Wilson St 98,000 0.22 6 High




2 Magdala St 58,000 0.13 13 Medium

12 Abbey St (south of Craigend) 84,000

13 Abbey St (south of Craigend) 150,000 0.16 10

Medium - Adopt only if option 14 is not feasible

17 Megalong St to Craigend St 254,000 0.16 16 Low

20 Craigend St (east of Hartley Esp) 72,000

21 Craigend St, west side of Spencer St, 390,000 0.10 7

High

34 Gladstone Rd (south of Wentworth Ave) 56,000 0.2 17 Low

43 22 Gladstone Road to 18-20 Scott Ave 267,000 0.31 2 High

46 Scott Ave (east of Herbert St) 164,000 - 14 Medium

57 Sublime Point Rd 205,000 0.11 12 Medium

Channel Modifications

9 Wilson St to Govett St 81,000 0.26 15

Low - Not required if

options 7 and 8 are feasible

27 Lachlan Ave to Craigend St (east of Victoria St) 40,000 -

19

Low

36 Western side of Everglades Ave from Northcote Road to Easter St 124,000 0.08 20 Low

37 West of Gladstone Road (between No’s 101 and 103-5) 42,000 0.98 5

High - Not required if option

35 is feasible

45 Channel running behind houses along Scott Ave (numbers 18 to 42) 103,000 - 21 Low

Detention Basins

35 Feasibility Study for Golf Course upstream of sub-catchment C2 N/A - 4

High - Further investigation

required

Levees/Flood Proofing

7 37 Govett St (Further investigation) 24,000 0.14 18 Low - Further investigation

required

8 50 Govett St (Further investigation) 24,000 0.70 11 Medium - Further


14 Abbey St (Further investigation) 24,000 0.32 9 Medium - Further


29 4 Everglades Ave 33,000 1.85 1 High - Further investigation

required

47 9 Hester Place 32,000 1.04 3 High


8.2 Public Exhibition and Summary of Submissions The Final Draft Report for the South Leura Floodplain Risk Management Study & Plan was submitted to Council and placed on Public Exhibition for information and comment. During the exhibition period, a summary of the key inputs and outputs associated with the study process (including the main outcomes and recommendations) was presented to Council, Stakeholders and the public at a Workshop held on 17 September, 2008. A total of nine submissions were received from the public and are summarised in Table 20. A common theme from the workshop and subsequent submissions was that the 149 Certificates should provide more details on the nature of flooding to differentiate between minor and serious flooding. These comments were made due to a concern that the 149 Certificate will affect property values.


Table 20: Summary of Submissions

Name and Address Main Issues Raised Responses

N. & E. G Györy 4 Everglades Ave, Leura

Comments on accuracy of modelling, documented flood extents and flood damages Identifies overland flooding from Everglades Ave as the case of flooding at this property and not flooding from the watercourse to the rear of the property. Implies incorrect assumptions regarding capture of flow at intersection of Everglades and Craigend St and Victoria and Craigend Sts. Comments that study does not account for obstructions due to fences. Comment that community consultation was inadequate.

The overall scope/extent of the study and data limitations can constrain the level of modelling detail in some areas. The accuracy of the investigations undertaken is in accordance with normal practice and considered appropriate for planning purposes. Question raised over the effectiveness of Option 29 as the bund may prevent overland flow from Everglades Ave returning to the watercourse. Option 29 requires further detailed investigation prior to implementation.

Robert and Beverley Deahm 9 Tennyson Ave Leura

Request for additional wording on 149 Certificates to detail minimal nature of flooding on their property.

Noted – for consideration by Council in implementing the Plan

Bruce Sinclair 2 Blaxland Ave Leura

149 Certificates will affect property values. Clarifications on 149 Certificate to degree of flooding required.


Allan Lederthoug Sublime Point Road

Request for BMCC to resolve flooding issue at their property

Option for Voluntary purchase of this property has been listed in the recommended options for adoption and implementation.

Phil Koperberg Member for Blue Mountains

Effectively forwarding the same submission as for 2 Blaxland Ave Leura

-

Robert Tinsey Pty Ltd on behalf of Ms ES Walker & SMA Walker 34 Hartley Esplanade, Leura

Disagree with the categorisation of their land as “flood prone”. Clarifications on 149 Certificate required.


Bryan Hardy 36 Craigend St, Leura

• Area not a floodplain • 149 Certificates will reduce

property values • Craigend St not listed as flood

prone

Craigend St was listed in table 9 as being flood prone. Table 14 lists culvert upgrade - Option 20, which was shortlisted and included in Plan

Lorraine Corrigan 15 Scott Ave, Leura

Request to include map of flood extent with 149 Certificate


Mr Stuart Ritchie 16 Scott Ave, Leura

Onus on BMCC to rectify inadequate capacity within easements



9.0 References Blue Mountains City Council, Better Living DCP for Single Dwellings and Subdivision Developments, Part C1.3 - Stormwater Blue Mountains City Council Local Environmental Plan 2005 New South Wales Department of Water Resources, Inverell Flood Damages Survey February 1991 Flood, prepared by Water Studies Pty Ltd, November 1991 New South Wales Department of Water Resources, Nyngan 1990 Flood Investigation – Chapter 9, prepared by Water Studies Pty Ltd, October 1990 New South Wales Government, Floodplain Development Manual: the management of flood liable land, April 2005 Public Works, Department of Water Resources, Losses and Lessons from the Sydney Floods of August 1986 Vol 1. and Vol. 2, Centre for Resource and Environmental Studies, Australian National University, and Environmental Management Pty Ltd Sydney – September 1990 The Institution of Engineers Australia, Australian Rainfall and Runoff, 1998


Appendix A Figures

South Leura Floodplain Risk Management Study & Plan - 29 April 2008 Page A

Appendix B Survey Data

South Leura Floodplain Risk Management Study & Plan - 29 April 2008 Page B

Appendix B Survey Data The following data was provided by the Council: • Img1999InfraRed15cmTile5.tab – False colour photography, flown in 1999, incorporating Green,

Red and InfraRed Bands, scanned at 13cm grid cell size; • Img1998Colour1m.tab - True colour photography, flown in 1998, scanned at 1m grid cell size; • Pipe.tab – stormwater drainage pipes; • Pits.tab – stormwater drainage pits, headwalls, pollution control devices etc; • Sewer.tab – Sewage lines; • Creeks.tab – Creeks; • Contours_m.tab – Composite layer containing 1m contours where they are present and 10m

contours elsewhere; • Dtm4m.tab – Mapinfo grid of 4 m DEM derived as above using 1m contours; • Parcel_LU.tab – Parcel boundaries attributed with landuse; • LEPZone.tab – Land zonings; • first_order_catchments.tab – catchment boundaries for the whole Blue Mountains LGA, derived

using ArcGIS/Spatial Analyst from a 12m DEM. • Soil.tab – soil landscapes (Department of Natural Resources); • filldem2 – Arc grid of 12m digital elevation model derived from the above contours using Vertical

Mapper in Mapinfo; and • Dtm4m_fill – Arc Grid of 4 m DEM derived as above using 1m contours.

South Leura Floodplain Risk Management Study & Plan - 29 April 2008 Page B-1

Appendix C Assessment of Flood Responses

South Leura Floodplain Risk Management Study & Plan - 29 April 2008 Page C

k:\20018804.00 south leura flood study, floodplain mgt study and plan\eng-plan\reports\app c\app c assessment of flooding reponses.doc

1.0 Assessment of Flooding Reponses

1.1 Introduction An assessment has been carried out to ascertain flooding characteristics of flood events reported by residents within the South Leura catchment. This information has been extracted from the South Leura Flood Study and Floodplain Management Study Community Questionnaire that was distributed to residents in June 2004. Each response was allocated a unique identification (ID) number so that any information pertaining to the response could always be tracked. A total of 112 responses were received from the distributed questionnaires, one of which could not be mapped because the resident had returned a blank questionnaire and not supplied their address. Of these responses, 41 residents reported historical flooding, however, not all of the reports were related to creek flooding and some appeared to be nuisance flooding due to inadequate stormwater management. To fulfil the objectives of the flood study and limit flooding to only creek flooding, a flooding assessment was carried out to separate nuisance from creek flooding. Secondly, the assessment was undertaken to help identify any hotspot areas where a series of properties may have reported creek or nuisance flooding.

1.2 Methodology All 41 properties reporting historical flooding were investigated in detail by considering the description of flooding, location, extent and duration. This was then compared against topographical information, location of stormwater infrastructure such as pits and pipes, easements and aerial photography. The 41 properties used in the assessment are listed in the complete list of responses in Attachment B. Screen outputs for each property assessed are contained in Attachment C for all 41 properties. To determine whether the reported flooding was nuisance or creek, the criteria outlined in Table 1 was followed.

Table 1: Assessment of Flooding Criteria

Flooding Type Assessment Criteria Creek • Property located within significant depression resembling creek

• Property was located over an identified creek* • Property was located in close proximity to an identified creek* • Resident made reference to a creek within their property • Resident reported historical nuisance flooding, however site characteristics

illustrated potential creek flooding Nuisance • Property was located on low side of road

• Resident reported surface runoff from neighbouring property • Resident reported surface runoff or overland flows from road • Flooding reported due to blocked stormwater infrastructure

Nuisance/Creek • No clear distinction between Nuisance or Creek Resolved • Resident reported historical nuisance flooding, however issues

subsequently resolved by the implementation of an appropriate solution *Identified creek – as identified by Blue Mountains City Council’s GIS database This information has also been mapped in MapInfo to illustrate the spatial distribution and assist in identifying hotspot areas where a series of properties may have reported creek or nuisance flooding.


1.3 Results The results indicate that a majority of the reported flooding is nuisance which is in agreement with the characteristics of the South Leura catchment. The catchment does not have expansive low-lying or floodplain areas, rather it is reasonably steep in many areas. The results are summarised in Table 2.

Table 2– Summary of Flooding Type

Flooding Type Count Nuisance 19 Creek 13 Nuisance/Creek 5 Resolved 4 Further details on the assessment are provided in Attachment D and mapping of results is shown in Figure 5 Questionnaire Results Map – Flooding Assessment in Appendix A of the South Leura Floodplain Management Study and Plan. In terms of hotspot areas, there are numerous areas that have been identified including the following:

• Creek running southeast through properties at 58 Govett Street and 37 Govett Street

• Open channel through properties at 5 Craigend Street to 7 Abbey Street, and section within the rear of 59 Grose Street

• Open channel through rear of properties along Scott Ave between numbers 16 and 28

• Properties at 27, 31, and 33 Sublime Point Road Other isolated hotspots that where identified include the following locations:

• Properties 8 and 10 Wascoe Street • Property at 7 Spencer Street • Property at 101 Gladstone Road • Property at 28 Kurrawang Street

1.4 Conclusions It can be concluded that about half of the reports of flooding pertained to creek type flooding and the balance of reports were nuisance flooding as a consequence of inadequate stormwater management. Inadequate information has been supplied in the questionnaires with regards to historical flood levels or flood marks to quantify the flooding extents and depths to facilitate calibration. However, the hotspot areas identified will provide valuable guidance and be used to confirm results of the modelling in these particular areas.


Attachment A – Residents Questionnaire

SOUTH LEURA FLOOD STUDY AND FLOODPLAIN MANAGEMENT STUDY

COMMUNITY QUESTIONNAIRE

Please complete this questionnaire for the South Leura area that you live in or have property. Answers to any question will be valuable to us in the completion of the study. The information you provide will only be used to complete the study and will not be used for any other purpose.

Please place your completed questionnaire in the postage paid envelope provided and return it by Wednesday, 30th June 2004.

Please note: You may tick more than one box if applicable.

Your address:

_____________________________________________________________________________________

_____________________________________________________________________________________

Name of Business/Organisation (if applicable) _______________________

Q1. What type of property do you have?

a. House b. Business c. Farm or rural activities d. Vacant land e. Other _______

Q2. What is the residential status of your property?

a. Owner occupied b. Tenant only c. Conducting any business at property

d. Other (please specify ) _________________________

Q3. For how long have you lived or owned this property?

a. Less than 1 year b. 1 year to 5 years c. 5 years to 20 years

d. More years (please specify)_______________

Q4. How many people live in the property?

Q5. If your property is used for business, how many people work here?

Q6. Do you plan to make any change to your property? If yes please specify.

a. Minor extensions b. New dwelling c. Dual occupancy e. Subdivision



f. Other (please specify) _________________________________

Q7. Have you put any application to Council to get approval for any development?

a. No b. Yes (please specify) _________________________________

Q8. What do you know about flooding in your property and surrounding area?

a. No information b. Flood levels from Council

d. From relatives, neighbours, friends or the previous owner

e. I have seen flooding in my property and/or surrounding area

f. Other Please specify_____________________________________

Q9. Have you ever had flood problem at your property?

a. No b. Yes c. Only during major storm event

If yes, please give some detail (e.g year of flooding, how bad was the flood, extent of flooding and

damages, etc.)?

…………………………………………………………………………………………………………………………………………………………………………………………

…………………………………………………………………………………………………………………………………………………………………………………………

…………………………………………………………………………………………………………………………………………………………………………………………

…………………………………………………………………

Q10. What has been the biggest flood you have experienced?

(please specify which year)

Q11. Do you remember what was the maximum depth of water and the location in your property?

a. No b. Yes (please specify)



Q12. Have you ever been informed prior to any flood in your area?

a. No b. Yes

If yes please specify the date, the warning time you received and from whom you heard about the flood.

____________________________________________________________________________

Q13. Have you ever had to evacuate your property due to the flood?

a. No b. Yes

If yes, please specify date and for how long? _________________________________________________

Q14. In the largest flood you have experienced, what has been the approximate cost of the damage caused by the flood?

a. No cost b. Yes $

Q15. If a development was to go ahead, in your opinion what Council should do to minimise flood related risks?

Not allow any development on flood prone land

Not allow development in locations that extremely pose a hazard to people

Advise the developer of the flood risk, but allow to decide

Place restrictions on new development (e.g make sure floor levels of new development are above estimated flood levels at the site).

Allow the development to go ahead in the flood prone land, however educate the resident how to respond to the flood

Q16. How should Council should notify residents about potential impact of flooding?

Notify the residents and the property owner on a regular basis about potential impact of flood



Notify prospective purchasers about potential impact of flooding

No notification is required

Q17. If you think you could provide more relevant information, please provide your telephone number so we could contact you.

Name: ____________________________________

Work No: ____________________________________

Home No: ____________________________________

Please specify what time is best to contact you. _______________________________________

Q18. Please provide your comments about flooding issues you think should be investigated?

…………………………………………………………………………………………………………………………….……………………………………………………………

…………………………………………………………………………………………………………………………………………………………………………………………

…………………………………………………………………………………………………………………………………………………………………………………………

…………………………………………………………………………………………………………………………………………………………………………………………

…………………………………………………………………………………………………………………………………………………………………………………………

Please place your completed questionnaire in the postage paid envelope provided and return it before Wednesday, 30th June 2004.

HOW CAN I FIND MORE ABOUT THE STUDY?

For more information about the South Leura Flood Study, Floodplain Management Study & Plan you can contact: Dr Sharif Fazeli Dr Mehdi Khiadani Catchment Stormwater Officer Senior Flood Engineer Blue Mountains City Council Maunsell Australia Pty Ltd Locked Bag 5 Katoomba NSW 2780 PO Box Q410, QVB Post Office Email: [email protected] Sydney, NSW 1230 Tel: 02 4780 5496 E-mail: [email protected] Fax: 02 4780 5562 Tel +61 2 8295 3600

Fax +61 2 9262 5060


Attachment B ID No Address

St. No. St Name Suburb 1 4 Balmoral Road LEURA 2 23 St Georges Road LEURA 3 11 Northcote Road LEURA 4 5 Wascoe Street LEURA 5 1 Hester Road LEURA 6 59 Grose Street LEURA 7 6 Spencer Street LEURA 8 75 Megalong Street LEURA 9 10 Wascoe Street LEURA

10 31 Sublime Point Road LEURA 11 28 Kurrawang Street LEURA 12 23 Holmes Street LEURA 13 36 Northcote Road LEURA 14 8 Wascoe Street LEURA 15 7 Lachlan Avenue LEURA 16 67 Lett Street KATOOMBA17 2A Craigend Street LEURA 18 26 Commonwealth Street LEURA 19 30 Gordon Road LEURA 20 135 Railway Parade LEURA 21 56 Gladstone Road LEURA 22 5 Craigend Street LEURA 23 10 Craigend Street LEURA 24 10 Tennyson Avenue LEURA 25 38 Sublime Point Road LEURA 26 33 Everglades Avenue LEURA 27 5 Albert Street LEURA 28 17 Lone Pine Avenue LEURA 29 113 Gladstone Road LEURA 30 101 Gladstone Road LEURA 31 35 Hester Road LEURA 32 244-246 Leura Mall LEURA 33 34 Kurrawang Street LEURA 34 14 Everglades Avenue LEURA 35 26A Hartley Esplanade LEURA 36 0 Megalong Street LEURA 37 8 Spencer Street LEURA 38 13 Everglades Avenue LEURA 39 25 Everglades Avenue LEURA 40 11 Everglades Avenue LEURA 41 13-15 Hester Place LEURA 42 58 Govett Street KATOOMBA43 10 Blaxland Avenue LEURA 44 15-17 Wentworth Avenue LEURA 45 11 Blaxland Avenue LEURA 46 41 Murray Street LEURA


ID No Address St. No. St Name Suburb 47 45 Murray Street LEURA 48 51-53 Morven Road LEURA 49 23 Cliff View Road LEURA 50 12 Scott Avenue LEURA 51 9 Railway Parade KATOOMBA52 13 Orchard Lane LEURA 53 9 Blaxland Avenue LEURA 54 8 Galston Cres LEURA 55 15 Spencer Street LEURA 56 10-12 Hartley Esplanade LEURA 57 14 Hester Road LEURA 58 18-20 St Georges Road LEURA 59 38 Scott Avenue LEURA 60 26 Hartley Esplanade LEURA 61 97 Railway Parade LEURA 62 27 Sublime Point Road LEURA 63 7 Craigend Street LEURA 64 16 Scott Avenue LEURA 65 33-35 Kurrawang Street LEURA 66 28 Hartley Esplanade LEURA 67 13 Easter Street LEURA 68 25 Abbey Street LEURA 69 11 Abbey Street LEURA 70 242 Leura Mall LEURA 71 37-39 Kurrawang Street LEURA 72 11 Easter Street LEURA 73 39 Wilson Street KATOOMBA74 24 Commonwealth Street LEURA 75 17 Abbey Street LEURA 76 16 Vale Street LEURA 77 33 Sublime Point Road LEURA 78 3 Morven Road LEURA 79 106 Gladstone Road LEURA 80 11 Willoughby Road LEURA 81 240 Leura Mall LEURA 82 175 Megalong Street LEURA 83 49 Sublime Point Road LEURA 84 107 Gladstone Road LEURA 85 7 Blaxland Avenue LEURA 86 238 Leura Mall LEURA 87 16 Gladstone Road LEURA 88 30 Hartley Esplanade LEURA 89 7 Abbey Street LEURA 90 37 Govett Street KATOOMBA91 4 Craigend Street LEURA 92 28 Scott Avenue LEURA 93 182 Megalong Street LEURA 94 18-20 Scott Avenue LEURA 95 45 Sublime Point Road LEURA 96 4 Everglades Avenue LEURA


ID No Address St. No. St Name Suburb 97 24 Scott Avenue LEURA 98 96-98 Craigend Street LEURA 99 32 Kurrawang Street LEURA

100 3 Beattie Street LEURA 101 6 Woodford Street LEURA 102 7 Willoughby Road LEURA 103 26 Sublime Point Road LEURA 104 14 Everglades Avenue LEURA 105 7 Spencer Street LEURA 106 10 Wascoe Street LEURA 107 34 Hartley Esplanade LEURA 108 43 Wilson Street KATOOMBA109 7 Railway Parade KATOOMBA

110 3 Govett St. KATOOMBA

111 11 Lone Pine Ave. LEURA


Attachment D

ID No Assessment Comments

3 Nuisance Resident blames problem on road shoulder construction.

6 Creek No. 57 Grose relevelled site which may have encroached onto waterway.

9 Nuisance/Creek 1m depth of flooding reported, time unknown. Property appears to be located in depression (no creek identified)

10 Nuisance/Creek Property located in depression. No creek has been identified. Resident has reported flooding due to blocked pipe in Golf Course.

11 Creek Refer ID105

14 Creek Property appears to be located in depression (no creek identified)

17 Nuisance Property appears to be located directly in an identified creek. Overland flows/sheet flow reported in 1998

21 Resolved Introduction of vegetated cutting in Gladstone rd has alleviated flooding problem.

22 Creek Property adjacent to an identified creek. 300mm of flooding reported in 1994 in cellar.

24 Nuisance Nature strip area in Tennyson Ave appears to have some localised nuisance flooding issues.

27 Nuisance Property on low side of Albert St, no kerb & gutter, overland flow path through property. Flooding reported in 2003/04 up to front veranda RL.

29 Nuisance Overland flows from Gladstone Rd heading north-westerly have been reported to have caused nuisance flooding (ankle deep) on 27/02/01. Raised bank on northwest corner of the intersection of Jamieson St and Gladstone Rd is not high enough.

30 Creek Property located over identified creek in low point. Flooding of 18 inch depth (450mm) reported in 2003.

34 Nuisance Flooding reported in 2003/04 comprising of "large pool" in front yard/driveway. Overland flows reported from Northcote Rd around to Everglades Street.

37 Nuisance Property located in sag in Spencer St. Flooding depth of about 2/3ft experienced 15 years ago (location unclear)

39 Nuisance Flooding reported to have been experienced due to pipe blockage in Everglades St south of Northcote Road in 2001.

42 Creek Creek runs in the property located directly behind (west) this property. Resident has reported that this creek floods during prolonged period of rain.

43 Resolved Dwelling appears to be located about 50m away from identified creek. Resident has identified that floods have occurred during major storm events.

44 Nuisance Property located in sag in Wentworth Ave. Overland flows to a depth of 600mm have been reported to enter property along western boundary (no easement provided).

48 Nuisance Flooding in 2003 reported due to a blocked drain and pits at the cul del sac end of Morven Rd. Overland flow path may need to be formalised.

56 Nuisance/Creek Nuisance flooding has been reported due to blocked drainage system. However, an open channel appears to run through the western boundary of the property.

62 Nuisance/Creek Property located in depression. No creek has been identified. Resident has reported flooding about 75cm over open drain in 2002. Flow width in front yard 10m and about 15cm deep.

64 Creek Flooding reported in Easter 2003 to a depth of 150mm in rear yard. Identified creek runs through property.

68 Nuisance Flooding experienced due to blocked drain in street.

77 Nuisance/Creek Property located in depression. No creek has been identified. Resident has reported flooding about 7 inches (175mm) due to overland flows from Sublime Point Rd in 2002/03.


ID No Assessment Comments

78 Resolved Overland flows experienced in mid 1990 to a depth of 6cms through property. No further issues since the introduction of kerb & gutter in rear lane/access rd.

79 Nuisance Overland flows experienced from golf course.

80 Nuisance Minor flooding reported in front garden. 100mm flow depth reported to have occurred in adjacent property, however, adjoining properties have not reported any flooding.

82 Creek Flooding of backyard along fenceline reported. Creek appears to run through property north-south direction.

87 Nuisance Stormwater drain located in easement along southern boundary has flooded property on previous occasion and is in poor shape.

89 Creek Resident has indicated minor flooding of garden presumably located in the backyard. Identified creek runs along western boundary, possible future creek flooding in major events

90 Creek Identified creek runs through property. Resident has reported frequent minor flooding believed to be as a result of blocked drainage system in Govett St.

92 Creek Flooding experienced in 2002 in backyard due to creek being blocked. Identified creek runs along northern boundary.

94 Creek Backyard flooded due to flood in 2000 to a depth of about 150mm. Identified creek runs along northern boundary.

96 Nuisance Resident has reported flooding due to overland flows from Everglades St. However, creek has been identified through property, possible future creek flooding.

99 Nuisance Stormwater flooding reported to have occurred in 1996 (details not provided). Property appears to be located in depression.

101 Resolved Flooding experienced in 1977/78 before of diversion of flows due to introduction of new drainage works in Railway Pde.

103 Nuisance Council needs to be liaised with, to determine exact history.

104 Nuisance Refer ID 34

105 Creek Property located over identified creek. Flooding reported in 1998 and in major storms.

107 Nuisance Issue appears to be an interallotment drainage issue due to runoff from 27A Blackheath St

Appendix D Hydrological Model

South Leura Floodplain Risk Management Study & Plan - 29 April 2008 Page D

Appendix D Hydrological Model Table D1: Catchment A

Sub-catchment Total Area

(ha) Existing Conditions

% Impervious

Fully Developed Conditions

% Impervious Vectored Slope (%)

A1-1 14.10 25 50 7.3 A1-2 17.10 25 50 8.6 A1-3 0.62 40 80 8.8 A1-4 0.17 70 80 13.8 A1-5 1.85 10 75 1.8

A2-1 8.58 25 35 12.5 A2-2 6.50 25 75 4.2 A2-3 0.47 10 80 3.3

A3-1 3.36 40 60 5.5 A3-2 4.58 30 40 19.9 A3-3 9.73 35 40 3.9

A4-1 7.31 25 40 14.2

A5-1 0.58 5 40 2

A6-1 1.12 40 40 22.8 A6-2 1.86 35 65 20.5 A6-3 0.31 30 75 14.3 A6-4 0.06 40 40 16 A6-5 0.77 45 70 14.8 A6-6 0.41 40 100 14.2 A6-7 0.62 65 90 9 A6-8 0.88 40 50 10.1 A6-9 0.05 100 100 10

A6-10 0.01 100 100 6.3 A6-11 0.22 100 100 13 A6-12 4.26 25 40 7.2 A6-13 3.20 25 40 4.5

A7-1 0.50 25 40 1.2

A8-1 10.00 30 30 7.3

A9-1 2.72 35 32 17.2

A10-1 34.70 20 20 8.5

A11-1 70.41 30 40 8.2

South Leura Floodplain Risk Management Study & Plan - 29 April 2008 Page D-1

Table D2: Catchment B



% Impervious



B1-1 5.60 70 70 9.2 B1-2 6.98 40 40 4.3 B1-4 13.35 30 40 9.1

B2-1 17.56 30 40 7.2 B2-2 13.98 40 40 8.3 B2-3 13.40 40 40 8.2

B3-1 11.97 10 10 13.4 B3-2 16.91 20 20 16.6

Table D3: Catchment C



% Impervious



C1-1 0.95 40 40 16.9 C1-3 4.90 40 40 9.4 C1-5 4.66 40 40 5.4 C1-8 10.27 40 40 6.2 C1-9 3.33 40 40 9.3 C1-11 7.69 30 35 11.3 C1-12 4.33 5 6 18.2

C2-3 10.07 15 15 4.8 C2-5 5.35 40 40 4.1 C2-6 2.76 5 35 19.8

C3-1 1.55 0 5 13

Table D4: Catchment D



% Impervious



D-1 3.85 15 20 7.7 D-2 0.49 40 40 7.2 D-3 7.98 15 35 17.8


Table D5: Catchment E



% Impervious



E1-1 1.63 0 0 5.9 E1-2 0.88 0 0 6.2 E1-3 1.55 10 10 6.6 E1-4 0.063 80 80 4.4 E1-5 0.088 80 80 3.3 E1-6 0.0251 10 10 19

E1-7a 0.3469 5 5 3.4 E1-7b 0.0301 10 10 13.4 E1-8 0.1193 5 5 8.9 E1-9 1.3069 10 10 7.2

E1-10 0.7234 10 10 8.6 E1-11 0.7585 15 15 14.4 E1-12 0.1622 15 15 20.8 E1-13 0.1587 15 15 18.7 E1-14 0.5 15 15 16.9 E1-15 3.159 10 10 12.9 E1-16 0.8799 15 15 17.2 E1-17 0.6244 50 50 4.8 E1-18 0.164 10 10 12.1 E1-19 1.7338 15 15 15.95 E1-20 4.6851 25 25 15.1 E1-21 11.9499 5 10 13.73

E2-1 0.920892 30 40 7.3 E2-2 6.01764 15 20 6.3

E3-1 9.12411 5 5 19.3

Table D6: Catchment F



% Impervious



F1-1 5.14 30 40 13.3 F1-2 4.03 35 40 10.9 F1-3 18.39 20 35 7.9 F1-4 39.87 10 30 8 F1-5 6.73 20 20 12.5

F2-1 28.03 30 40 12.3




% Impervious



F2-2 7.39 20 35 18.7

F3-1 12.48 30 30 13.1 F3-2 10.92 10 20 13.7

Table D7: Comparison of Probabilistic Rational Method and Rafts Results for 100 Year ARI storm event

Time of Concentration Rational Method - Q100 Rafts - Q100 XP RAFTS Node

mins m3/s m3/s

A1-5 30.2 11.20 10.43

A2-3 22.5 6.00 5.10

A3-3 39.2 19.36 19.40

A4-1 16.9 3.25 3.13

A5-1 40.9 21.15 20.89

A6-13 21.5 5.45 5.63

A7-1 43.7 24.31 23.97

A8-1 45.5 26.39 25.92

A9-1 11.6 1.44 1.34

A10-1 51.3 33.69 31.90

A11-1 39.9 20.10 19.30

J.A-7 60.1 47.02 45.78

B1-4 27.3 9.08 9.44

B2-3 33.6 14.00 13.21

B3-2 45.6 26.54 28.50

C1-12 31.0 11.84 11.66

C2-6 23.9 6.78 5.53

C3-1 36.5 16.67 17.25

D-1 13.2 1.91 1.46

D-2 13.8 2.11 1.63

D-3 20.6 4.96 4.43

E1-1 25.0 7.55 5.30

E2-2 16.5 3.11 2.38

JE-1 27.9 9.47 7.54

E1-2 32.0 12.68 10.32

E3-1 18.4 3.91 3.83

JE-2 34.7 14.98 12.14


Time of Concentration Rational Method - Q100 Rafts - Q100 XP RAFTS Node

mins m3/s m3/s

F1-4 39.3 19.47 16.67

F2-2 30.7 11.61 12.17

J.F-1 46.1 27.03 24.94

F1-5 47.2 28.44 26.26

F3-2 26.3 8.35 8.24

J.F-2 50.8 33.22 32.94


Rafts OutputSub-Catchment A

Node 15m 30m 45m 1hr 1.5hr 2hr 3hr 4.5hr 6hr 9hr 12hr

A1-1 2.26 2.61 2.92 3.19 4.38 4.41 3.79 3.70 3.16 2.94 3.08

A1-2 2.78 3.22 3.58 3.96 5.41 5.50 4.67 4.52 3.83 3.57 3.74

A1-3 0.17 0.22 0.20 0.27 0.31 0.30 0.20 0.19 0.14 0.13 0.14

A1-4 0.25 0.31 0.26 0.35 0.41 0.39 0.25 0.24 0.18 0.17 0.17

A1-5 5.23 6.01 6.87 7.60 10.16 10.43 8.92 8.77 7.54 7.02 7.36

A2-1 1.50 1.95 2.03 2.51 3.47 3.40 2.68 2.49 1.94 1.80 1.89

A2-2 2.08 2.90 3.22 3.77 4.89 4.99 3.96 4.05 3.38 3.15 3.30

A2-3 2.13 2.97 3.31 3.89 4.99 5.10 4.06 4.16 3.47 3.24 3.39

A3-1 6.81 9.39 10.64 12.08 14.39 16.13 13.65 13.56 11.72 10.89 11.46

A3-2 1.06 1.44 1.32 1.83 2.20 2.04 1.46 1.37 1.03 0.96 1.01

A3-3 8.21 11.09 13.08 14.68 17.81 19.40 16.33 17.00 14.53 13.60 14.27

A4-1 1.34 1.78 1.77 2.30 3.13 3.00 2.30 2.15 1.65 1.54 1.61

A5-1 9.38 12.80 14.33 16.06 19.51 20.89 17.57 18.83 16.28 15.05 16.00

A6-1 0.37 0.48 0.40 0.53 0.60 0.58 0.36 0.34 0.26 0.24 0.25

A6-2 0.88 1.17 1.02 1.38 1.55 1.49 0.96 0.90 0.68 0.63 0.66

A6-3 0.08 0.13 0.11 0.15 0.17 0.16 0.10 0.09 0.07 0.07 0.07

A6-4 0.03 0.03 0.02 0.03 0.04 0.04 0.02 0.02 0.01 0.01 0.01

A6-5 0.27 0.36 0.29 0.39 0.44 0.43 0.27 0.25 0.19 0.18 0.18

A6-6 0.40 0.53 0.44 0.58 0.66 0.64 0.40 0.37 0.28 0.26 0.27

A6-7 0.25 0.27 0.21 0.30 0.34 0.33 0.20 0.19 0.14 0.13 0.14

A6-8 0.49 0.58 0.48 0.67 0.77 0.75 0.48 0.45 0.34 0.32 0.33

A6-9 0.88 1.07 0.90 1.24 1.44 1.37 0.89 0.84 0.63 0.59 0.62

A6-10 0.97 1.21 1.01 1.39 1.61 1.54 0.99 0.93 0.71 0.66 0.69

A6-11 1.98 2.49 2.11 2.88 3.29 3.15 2.02 1.90 1.43 1.34 1.40

A6-12 2.44 3.11 2.83 3.85 4.58 4.55 3.32 3.10 2.39 2.23 2.33

A6-13 2.85 3.55 3.35 4.57 5.38 5.63 4.13 3.91 3.11 2.90 3.03

A7-1 11.65 15.68 16.75 19.36 22.73 23.97 20.18 22.19 19.44 18.02 19.04

A8-1 12.32 17.37 17.97 21.26 24.48 25.92 21.72 24.44 21.26 19.82 20.58

A9-1 0.70 0.89 0.83 1.14 1.34 1.25 0.87 0.81 0.61 0.57 0.60

A10-1 9.27 20.58 22.48 26.25 29.79 31.90 27.44 30.03 27.46 26.08 25.81

A11-1 12.86 13.17 11.64 14.75 19.30 18.13 15.78 16.59 15.30 14.16 15.05

J.A-7 17.42 25.62 32.08 35.48 40.49 43.72 38.87 45.78 40.43 38.07 40.86

100 Year ARI, Peak Flows (m3) for Various Durations

18/12/2006 5:29 PM

Rafts OutputSub-Catchment B


B1-1 2.33 2.26 1.96 2.42 2.88 2.77 1.78 1.67 1.26 1.18 1.23

B1-2 3.66 3.56 3.23 3.88 4.71 4.95 3.67 3.49 2.83 2.63 2.76

B1-4 5.48 5.71 5.68 6.99 8.04 9.44 7.20 6.94 5.81 5.41 5.67

B2-1 3.29 3.57 3.55 4.17 5.59 5.40 4.63 4.57 3.92 3.65 3.83

B2-2 6.56 6.51 6.35 7.53 9.95 9.64 8.25 8.16 7.03 6.54 6.87

B2-3 8.05 8.76 8.72 10.65 13.03 13.21 10.69 11.38 9.88 9.16 9.69

B3-1 14.50 16.31 15.97 19.98 22.84 25.01 20.05 20.77 17.94 16.77 17.61

B3-2 15.88 19.34 19.73 23.32 25.75 28.50 23.14 24.78 21.44 19.83 21.13


18/12/2006 5:29 PM

Rafts OutputSub-Catchment C


C1-1 0.28 0.38 0.32 0.44 0.49 0.48 0.30 0.29 0.22 0.20 0.21

C1-3 1.47 1.66 1.46 2.05 2.60 2.38 1.84 1.72 1.32 1.23 1.29

C1-5 2.36 2.46 2.42 3.08 3.92 3.96 3.18 2.97 2.37 2.21 2.31

C1-8 3.66 4.51 4.46 5.34 6.45 7.21 5.89 5.62 4.67 4.35 4.56

C1-9 0.87 0.98 0.82 1.21 1.52 1.40 1.05 0.98 0.75 0.70 0.73

C1-11 5.67 6.93 6.75 8.10 10.11 10.72 8.57 8.54 7.13 6.63 6.96

C1-12 6.47 7.95 7.56 9.31 11.17 11.66 9.57 9.57 8.06 7.49 7.87

C2-3 2.14 2.19 1.97 2.50 3.25 3.08 2.63 2.62 2.25 2.09 2.19

C2-5 3.09 2.96 2.95 3.60 4.41 4.67 3.74 3.90 3.41 3.16 3.34

C2-6 3.74 3.73 3.50 4.28 5.07 5.53 4.33 4.53 3.97 3.68 3.90

C3-1 9.97 11.63 11.08 13.79 16.26 17.25 14.18 14.40 12.35 11.47 12.08


18/12/2006 5:29 PM

Rafts OutputSub-Catchment D


D-1 0.54 0.81 0.90 1.04 1.39 1.46 1.18 1.09 0.87 0.81 0.85

D-2 0.62 0.91 1.00 1.16 1.57 1.63 1.31 1.22 0.98 0.91 0.95

D-3 1.95 2.63 2.73 3.35 3.88 4.43 3.55 3.38 2.77 2.58 2.70


18/12/2006 5:29 PM

Rafts OutputSub-Catchment E


E2-1 0.20 0.27 0.24 0.33 0.42 0.39 0.29 0.27 0.21 0.19 0.20

E2-2 0.89 1.34 1.51 1.69 2.15 2.38 1.97 1.88 1.56 1.45 1.52

J.E-1 3.53 5.38 5.82 6.89 8.10 9.01 7.45 7.10 5.97 5.56 5.82

E1-21 5.02 7.80 8.41 10.02 11.47 13.10 10.58 10.32 8.64 8.04 8.43

J.E-2 6.34 9.57 10.37 12.38 14.31 16.03 13.01 12.73 10.68 9.94 10.42

E1-1 0.22 0.35 0.38 0.46 0.58 0.63 0.50 0.46 0.37 0.34 0.36

E3-1 1.65 2.14 2.22 2.90 3.60 3.83 2.87 2.68 2.06 1.92 2.01

E1-2 0.15 0.20 0.21 0.27 0.34 0.36 0.27 0.25 0.20 0.19 0.19

J1 0.38 0.55 0.59 0.72 0.92 0.99 0.77 0.72 0.57 0.53 0.55

E1-4 0.61 0.90 0.97 1.18 1.50 1.64 1.27 1.18 0.93 0.87 0.91

E1-3 0.24 0.34 0.37 0.45 0.60 0.63 0.49 0.45 0.35 0.33 0.34

E1-5 0.61 0.92 0.98 1.20 1.52 1.66 1.28 1.20 0.95 0.88 0.93

E1-6 0.61 0.92 0.99 1.21 1.52 1.66 1.29 1.21 0.96 0.89 0.93

E1-8 0.03 0.04 0.04 0.05 0.06 0.06 0.04 0.04 0.03 0.03 0.03

E1-9 0.26 0.33 0.34 0.44 0.58 0.60 0.45 0.42 0.32 0.30 0.31

E1-10 0.40 0.50 0.51 0.67 0.88 0.91 0.67 0.63 0.49 0.45 0.47

E1-11 0.56 0.68 0.68 0.93 1.16 1.22 0.91 0.84 0.65 0.61 0.64

E1-12 1.11 1.55 1.68 2.05 2.64 2.79 2.17 2.06 1.65 1.53 1.60

E1-13 1.18 1.66 1.80 2.19 2.81 2.98 2.33 2.19 1.77 1.64 1.72

E1-14 1.72 2.39 2.60 3.19 3.87 4.29 3.39 3.19 2.59 2.42 2.53

E1-15 0.62 0.75 0.77 1.03 1.34 1.34 1.00 0.93 0.71 0.66 0.69

E1-16 2.04 2.71 2.97 3.63 4.28 4.87 3.88 3.65 2.97 2.76 2.89

E1-17 0.19 0.21 0.17 0.24 0.31 0.29 0.20 0.19 0.14 0.13 0.14

E1-18 0.23 0.27 0.22 0.32 0.38 0.37 0.25 0.24 0.18 0.17 0.17

E1-19 2.34 3.06 3.32 4.07 4.81 5.43 4.31 4.11 3.36 3.13 3.27

E1-20 2.87 4.05 4.32 5.20 6.21 6.78 5.47 5.30 4.41 4.10 4.30

E1-7b 0.05 0.08 0.09 0.11 0.15 0.15 0.12 0.11 0.09 0.08 0.08

E1-7a 0.05 0.07 0.08 0.10 0.13 0.14 0.11 0.10 0.08 0.07 0.08


18/12/2006 5:29 PM

Rafts OutputSub-Catchment F


F1-1 1.07 1.40 1.25 1.79 2.29 2.13 1.63 1.52 1.16 1.08 1.13

F1-2 1.90 2.31 2.20 3.01 3.97 3.78 2.90 2.70 2.07 1.93 2.02

F1-3 3.69 5.22 5.69 6.93 8.24 8.58 7.25 7.18 6.17 5.73 6.02

F1-4 5.93 9.74 12.10 13.90 15.00 16.67 14.37 16.39 14.23 13.09 14.09

F1-5 10.48 16.99 19.22 21.24 24.15 26.26 22.52 25.92 23.45 21.72 22.77

F2-1 5.36 6.00 6.14 7.20 9.92 9.73 8.12 7.70 6.31 5.87 6.15

F2-2 6.74 7.72 7.57 9.47 12.17 11.81 9.70 9.58 7.94 7.38 7.74

J.F-1 9.67 16.19 18.36 20.17 22.56 24.94 21.35 24.65 22.17 20.47 21.83

F3-1 2.48 2.98 2.94 3.75 4.99 4.83 3.85 3.59 2.82 2.62 2.74

F3-2 3.85 5.28 5.15 6.75 7.98 8.24 6.49 6.32 5.27 4.91 5.14

J.F-2 13.772 21.161 24.013 26.313 31.148 32.935 28.145 31.293 28.402 26.402 27.802


18/12/2006 5:29 PM

Appendix E Hydraulic Model

South Leura Floodplain Risk Management Study & Plan - 29 April 2008 Page E

Appendix E Hydraulic Model Historical Flood events

All relevant rainfall data available for the area was obtained from the Bureau of Meteorology (BOM) and Sydney Water. Table 4 lists what data was obtained. Table 15: Daily Rainfall and Pluviograph data

Station Number Location Type Source

63227 Wentworth Falls Country Club Pluviograph data Daily Rainfall

Bureau of Meteorology

63039 Katoomba (Narrow Neck Road)

Pluviograph data Daily Rainfall

Bureau of Meteorology

563060 Katoomba (2 Dora St) Pluviograph data Sydney Water 63045 Leura Post Office Daily Rainfall Bureau of Meteorology 63092 Wentworth Falls Post Office Daily Rainfall Bureau of Meteorology 63264 Katoomba City Council Daily Rainfall Bureau of Meteorology 63173 Rothesay (Wentworth Falls) Daily Rainfall Bureau of Meteorology

None of the pluviograph rainfall stations exist within the study area. The closest station is the Sydney Water rainfall station (563060) which is located approximately 270m from the study area while the two BOM Stations at Wentworth Falls Country Club (63227) and Narrow Neck Road Katoomba (63039) are located approximately 1.2km and 2km away respectively. Historical flood events were identified by matching information provided by Council and from the questionnaire results with the daily rainfall and pluviograph data. Events identified are as follows: a) 11 March 2003; b) 26 – 31 March 2002; c) 28 February 2001; d) 8 August 1998; e) 2 – 8 March 1995; and f) 5 – 11 May 1980. Further analysis of events 1 to 4 was considered as they were more recent and also the catchment conditions can be considered to be similar to the current condition. Data for event 4 was only 60% complete and was discarded from further analysis. Only three events were considered and reported. Table 5 on the following page summarises what properties reported flooding in each event.

South Leura Floodplain Risk Management Study & Plan - 29 April 2008 Page E-1

Table 16: Summary of Reported Flooding events and Properties Affected

Properties Affected Flood event Questionnaire

ID No Address Catchment Type of

Flooding

27 5 Albert St B Nuisance 30 101 Gladstone Road C Creek

34, 104 14 Everglades Ave C Nuisance 48 51-53 Morvan Road F Nuisance

Spencer St B Creek Sublime Point Road** E Nuisance/Creek

1) 11 March 2003

Identified in Council’s Brief

Scott Ave F Creek

62 27 Sublime Point Road E* Nuisance/Creek

64 16 Scott Ave F Creek 2) 26-31 March 2002

91 28 Scott Ave F Creek 39 25 Everglades Ave C Nuisance 3) 28 February 2001 29 113 Gladstone Road D Nuisance

*Insufficient survey data available Properties that have been identified at risk of creek flooding have been analysed further. The model runs that have been carried out are shown in Table 6. Calibration of the models will be restricted to these locations. Note that event 3 has been excluded due to both complaints being identified as nuisance flooding. Nuisance flooding refers to flooding from surface water such as runoff from road entering property and driveways. Creek flooding refers to the rise in water level in the creek/natural watercourse and flooding the properties. Table 17: Model Runs for Historical Flood events

Flood event Catchment

1) 11 March 2003 B, C 2) 26 – 31 March 2002 F

Both of these events were input into RAFTS to produce hydrographs for export and input into SWMM. The results are discussed below. Event 1 – 11 March 2003 This storm event has been assessed as per ARR methods to be equivalent to a 6 hour 5 year ARI storm event, with a peak burst equivalent to a 30 minute 5 year ARI storm event. The storm event was run for Catchment B and C only as Catchment F was run for event 2. Catchment B From information provided by Council, flooding was recorded along Spencer St during this event. No specific information about the location of the flooding was provided. A major pipe system conveys flow along the western side of Spencer St to where it discharges to a channel at 14 Tennyson Ave. The model results for this storm event show no surcharging from the pipe system along Spencer St. The pipes here are 1200mm diameter. The flooding along Spencer St is likely to have been caused by overland flow or blocked pits.


Catchment C The results are shown in Table 7. Flooding was reported at 101 Gladstone Road (Node C2-4). The resident reported a water depth of 18 inches however did not specify where this level was recorded. The water level in the channel downstream of Gladstone Road as modelled in SWMM is 220mm. The survey data for this section indicates that the channel is quite wide (approximately 3m) and that the channel depth is approximately 0.5m. The results indicate that there is no overtopping of the channel banks, which does not correspond with the residents report. A sensitivity analysis was undertaken to determine the effects to changes in the blockage factors of the upstream culverts however the water depth of 220mm was the maximum that was achieved. It is possible that at the time of the event the channels were blocked meaning that there would be a higher flood level. It is also possible that the rainfall data used does not adequately represent the rainfall in this area. Table 18: event 1 – 11 March 2003, Results for Catchment C

Results Max Flow Max Vel Water Depth Elevation US Node DS Node Multi Link

Name m3/s m/s m RL m AHD

C1-1 C1-2 C1-1culv 0.08 3.61 0.13 969.27 - - C1-1over 0.00 0.00

C1-2 C1-3 C1-2trap 0.08 0.66 0.06 966.86 C1-3 C1-4 C1-3culv 0.41 2.77 0.30 948.93

- - C1-3over 0.00 0.00 C1-4 C1-5 c1-4chan 0.40 0.49 0.18 948.18 C1-5 C1-6 C1-5culv 0.58 3.05 0.56 937.96

- - C1-5over 0.00 0.00 C1-6 C1-7 c1-6chan 0.58 1.23 0.20 936.40 C1-7 C1-8 C1-7trap 0.58 1.38 0.25 933.25 C1-8 C1-10 C1-8culv 0.84 4.21 0.31 931.01

- - C1-8over 0.00 0.00 C1-9 C1-10 C1-9culv 0.23 4.04 0.13 931.80

- - C1-9over 0.00 0.00 C1-10 C1-11 C1-10chan 1.04 0.88 0.22 929.32 C1-11 C1-12 c1open6 1.49 2.50 0.64 907.64 C2-1 C2-2 C2-1chan 0.57 0.48 0.16 947.23 C2-2 C2-3 C2-2chan 0.53 0.60 0.14 938.64 C2-3 C2-4 C2-3culv 0.52 2.13 0.43 935.14

- - C2-3over 0.00 0.00 C2-4 C2-7 C2-4Chan 0.52 0.64 0.22* 934.45 C2-7 C2-8 C2-7chan 0.52 0.69 0.14 934.14 C2-8 C2-5 C2-8chan 0.51 0.66 0.17 932.17 C2-5 C2-6 C2-5chan 0.74 0.39 0.07 925.68 C2-6 C1-12 C2-6chan 0.87 3.35 1.15 888.33 C1-12 C-3A C1-12chan 2.51 3.82 0.43 879.33 C-3A Outlet dummy 2.60 3.90 0.44 872.94

* Water depth in channel downstream of Gladstone Road Event 2 – 28 March 2002 This storm event has been assessed to be equivalent to a 2 year 1.5 hour ARI storm event. The storm event was run for Catchment F. The results are shown in Table 8. Flooding was reported by 2


properties along Scott Ave (numbers 16 and 28). Detailed survey for part of this channel was undertaken and used in the modelling. Flow is piped from the rear of 22 Gladstone Road to 18-20 Scott Ave (F1-2 to F1-6), therefore any flow affecting 16 Scott Ave would be overland flow or surcharge from the pit located to the west of the property (F1-15). Flooding was reported during this event to a depth of 150mm though the location was not specified. However the model results show no surcharge from this pit during this event. A blockage factor analysis was undertaken however the results showed only minimal overland flow (0.002m/s). It is most likely that the flooding was caused by nuisance flooding. The average depth for the channel located at the rear of properties from 18-20 Scott Ave to 40 Scott Ave (F1-6 to F1-8) is 0.5m. The results below show that water does not overtop the banks during the modelled storm event indicating that the flow does not overtop the channel and encroach on properties. Access to the channels here was not possible during site visits and as such the channel conditions have been assumed to be similar to others in the catchment. A sensitivity analysis was undertaken by increasing the mannings n value, however flow was still contained within the channel.

Table 19: event 2 – 28 March 2002, Results for Catchment F

100-year ARI storm event Max Flow Max Vel Water Depth Elevation US Node DS Node Multi Link

Name m3/s m/s m RL m AHD

F1-12 F1-1 F1-12culv 0.58 2.71 0.89 935.51 - - F1-12over 0.08 0.67

F1-1 F1-5 F1-1culv 0.62 3.24 0.57 935.06 - - F1-1over 0.00 0.00

F1-5 F1-2 F1-5trap 0.62 1.49 0.34 934.20 F1-2 F1-13 F1-2culv 0.80 2.93 0.68 932.60

- - F1-2over 0.00 0.00 F1-13 F1-14 F1-13culv 0.80 3.12 1.13 931.34

- - F1-13over 0.00 0.00 F1-14 F1-15 F1-14culv 0.93 3.71 1.10 930.73

- - F1-14over 0.69 1.50 F1-15 F1-6 F1-15culv 0.81 3.44 1.17 928.07

- - F1-15over 0.00 0.17 F1-6 F1-7 F1-6trap 0.72 1.31 0.34 926.46 F1-7 F1-8 F1-7trap 0.68 1.71 0.39 922.97 F1-8 F1-9 F1-8chan 2.37 2.91 0.25 916.99 F1-9 F1-10 F1-9pipe 2.23 3.45 0.60 914.86

- - F1-9over 0.00 0.00 F1-10 F1-3 F1-10culv 2.23 3.50 0.91 913.06

- - F1-10over 0.00 0.00 F1-3 F1-11 F1-3chan 2.20 1.70 0.37 911.74 F1-11 F1-4/F2-2 F1-11chan 2.20 1.69 0.82 890.61 F2-1 F1-4/F2-2 F2-1chan 3.08 1.25 0.27 897.27

F1-4/F2-2 F1-5/F3-2 F1-4chan 11.57 1.68 0.55 862.55 F3-1 F1-5/F3-2 F3-1chan 1.41 0.65 0.19 904.69

F1-5/F3-2 OUTLET dummy 14.10 1.70 0.99 851.99


Hydraulic Network DataCatchment A

Culvert Size

Width Channel DepthChannel Depth

m m m % m m m mA1-1 A1-6 A1-1Culv1 27 0.014 948.7 948.565 Circular 0.5 0.25 0.75 2 0.6 - - - - -

- - A1-1over 27 0.014 949.8 949.7 Trapezoidal 0.37037 - - - - 20 1.1 - - -A1-3 A1-4 A1-3Culv 23 0.014 950.7 950.1 Circular 2.6087 0.25 0.75 1 0.3 - - - - -

- - A1-3over 23 0.014 952 951.8 Trapezoidal 0.43478 - - - - 20 0.5 - - -A1-4 A1-6 A1-4Culv 23 0.014 950.1 948.565 Circular 6.67391 0.25 0.75 1 0.3 - - - - -

- - A1-4over 23 0.014 951.8 949.7 Trapezoidal 9.56522 - - - - 20 0.5 - - -A1-6 J.A-1 A1-6chan 56 0.06 948.565 946.8 Natural 3.15179 - - - - - - 0.045 0.05 1.5A1-2 J.A-1 A1-2culv 11.5 0.014 947.6 946.8 Circular 6.95652 0.25 0.75 2 0.6 - - - - -

- - A1-2over 11.5 0.014 948 947.9 Trapezoidal 0.86957 - - - - 20 0.5 - - -J.A-1 A1-5 J.A-1Chan 120 0.05 946.8 945.3 Natural 1.25 - - - - - - 0.05 0.05 1.5A2-1 A2-4 A2-1Culv1 9.5 0.014 964.5 963.7 Circular 8.42105 0.25 0.75 1 0.375 - - - - -

- - A2-1Culv2 9.5 0.014 964.5 963.7 Circular 8.42105 0.25 0.75 1 0.45 - - - - -- - A2-1over 9.5 0.014 965 964.5 Trapezoidal 5.26316 - - - - 20 0.5 - - -

A2-4 A2-5 A2-4Chan 32 0.055 963.7 962.36 Natural 4.1875 - - - - - - 0.06 0.055 1A2-5 A2-2 A2-5chan 296 0.014 962.36 949 Natural 4.48986 - - - - - - 0.06 0.04 1.5A2-2 A2-3 A2-2culv 9 0.014 949.07 948.6 Circular 5.22222 0.25 0.75 1 0.45 - - - - -

- - A2-2over 9 0.014 950.01 949.83 Trapezoidal 2 - - - - 20 0.5 - - -A2-3 A2-3A A2-3AA 19 0.06 948.6 947.3 Natural 6.84211 - - - - - - 0.06 0.03 1.9

A2-3A A2-3B A2-3BB 37 0.06 947.3 946.1 Natural 3.24324 - - - - - - 0.06 0.03 1.36A2-3B A1-5 A2-3C 18 0.06 946.1 945.3 Natural 4.44444 - - - - - - 0.06 0.03 1.65A1-5 A3-1 A1-5Chan 64 0.05 945.3 944.6 Natural 1.09375 - - - - - - 0.06 0.03 1.5A3-1 J.A-3 A3-1Culv1 13 0.014 944.604 944.336 Circular 2.06154 0.25 0.75 1 0.6 - - - - -

- - A3-1Culv2 13 0.014 944.666 944.372 Circular 2.26154 0.25 0.75 1 0.6 - - - - -A3-2 A3-4 A3-2Culv 9 0.014 953.5 952.8 Circular 7.77778 0.25 0.75 1 0.45 - - - - -

- - A3-2over 9 0.014 954 953.5 Trapezoidal - - - - - 20 0.5 - - -A3-4 J.A-3 A3-4Trap 82 0.013 952.8 945.5 Trapezoidal 8.90244 - - - - 0.4 0.3 - - -J.A-3 A3-5 J.A-3trap 63 0.02 944.3 941.7 Natural 4.12698 - - - - - - 0.06 0.03 2A3-5 A3-3/A4-1 J.A-3chan 288 0.014 941.7 932.34 Natural 3.26005 - - - - - - 0.06 0.03 2

A3-3/A4-1 A5-1/A6-13 A3-3chan 68 0.014 932.34 930.8 Natural 2.26471 - - - - - - 0.06 0.03 4A2 (A2-6) A5-1/A6-13 dummy2 175 0.014 937.5 930.8 Natural 3.82857 - - - - - - 0.06 0.04 4

A5-1/A6-13 A7-1 A5-1chan 35 0.014 930.8 930 Natural 2.28571 - - - - - - 0.06 0.03 4A7-1 A7-2 A7-1culv 27.8 0.014 930 928.332 Circular 6 0.25 0.75 1 1.8 - 1.8 - - -A7-2 A8-1/A9-1 A7-2chan 218 0.014 928.332 922.53 Natural 2.66147 - - - - - - 0.06 0.03 2

A8-1/A9-1 A10-1 A8-1chan 600 0.014 922.53 902 Natural 3.42167 - - - - - - 0.06 0.03 2.5A10-1 A10-2 A10-1chan 70 0.014 902 886 Natural 22.8571 - - - - - - 0.06 0.03 2.5A11-1 A10-2 A11-1chan 77 0.014 900.32 886 Natural 18.5974 - - - - - - 0.06 0.03 2A10-2 Outlet A10-2chan 45 0.014 886 882 Natural 8.88889 - - - - - - 0.06 0.03 2A6-1 A6-2 A6-1pipe 28.8 0.014 948.75 947.53 Circular 4.23611 0.25 0.75 1 0.45 - - - - -

- - A6-1over 8.1 0.014 949.6 948.73 Trapezoidal - - - - - 20 1.1 - - -

Natural Channel

Entrance Loss

Exit Loss

Number of Barrels

Left/Right Bank -

Mannings n

Channel Mannings

n

Culvert DetailsUS Node DS Node

Multi Link Name

Trapezoidal Channel/ Overland Flow Path

LengthRoughness

Upstream IL

Downstream IL Shape

Conduit Slope

18/12/2006 5:42 PM


Culvert Size

Width Channel DepthChannel Depth

m m m % m m m m

Natural Channel

Entrance Loss

Exit Loss

Number of Barrels

Left/Right Bank -

Mannings n

Channel Mannings

n


Multi Link Name


LengthRoughness

Upstream IL

Downstream IL Shape

Conduit Slope

A6-2 A6-11 A6-2pipe 8.1 0.014 947.53 946.02 Circular 18.642 0.25 0.75 1 0.675 - - - - -- - A6-2over 8.1 0.014 948.73 948.27 Trapezoidal 5.67901 - - - - 20 0.5 - - -

A6-3 A6-10 A6-3pipe 8 0.014 947.63 946.74 Circular 11.125 0.25 0.75 1 0.45 - - - - -- - A6-3over 10 0.014 948.83 948.34 Trapezoidal - - - - - 20 0.5 - - -

A6-7 A6-8 A6-7culv 12.9 0.014 955.15 953.6 Circular 12.0155 - - - - - - - - -- - A6-7over 12.9 0.014 956 954.8 Trapezoidal - - - - v 20 0.6 - - -

A6-8 A6-9 A6-8pipe 45.8 0.014 953.6 947 Circular - 0.25 0.75 1 0.45 - - - - -- - A8-8over 45.8 0.014 954.8 948.6 Trapezoidal 13.5371 0.25 0.75 1 0.5 20 1.5 - - -

A6-4 A6-5 A6-4pipe 5.9 0.014 950.45 950.26 Circular 3.22034 0.25 0.75 1 0.375 - - - - -- - A6-4over 5.9 0.014 951.65 951.16 Trapezoidal 8.30508 - - - 20 0.45 - - -

A6-5 A6-6 A6-5pipe 4.5 0.014 950.26 948.58 Circular 37.3333 0.25 0.75 1 0.525 - - - - -- - A5-6over 10 0.014 951.16 949.3 Trapezoidal - - - - 20 1 - - -

A6-6 A6-9 A6-6pipe 10 0.014 948.58 947 Circular 15.8 0.25 0.75 1 0.525 - - - - -- - A6-6over 10 0.014 949.3 948.6 Trapezoidal - - - - 20 0.45 - - -

A6-9 A6-10 A6-9pipe 8.3 0.014 947 946.74 Circular 3.13253 0.25 0.75 1 0.75 - - - - -- - A6-9over 8.3 0.014 948.6 948.34 Trapezoidal - - - - 20 1.9 - - -

A6-10 A6-11 A6-10pipe 2.4 0.014 946.74 946.02 Circular 30 0.25 0.75 1 0.9 - - - - -- - A6-10over 2.4 0.014 948.34 948.27 Trapezoidal 2.91667 - - - 20 1.65 - - -

A6-11 A6-14 A6-11pipe 8 0.014 946.02 943.7 Circular 29 0.25 0.75 1 0.9 - - - - -- - A6-11over 8 0.014 948.27 947.7 Trapezoidal - - - - 20 0.6 - - -

A6-14 A6-15 A6-14pipe 62 0.014 943.7 939.372 Circular 6.98387 0.25 0.75 1 0.9 - - - - -- - A6-14over 62 0.014 947.7 941.372 Trapezoidal - - - - 0 0.45 - - -

A6-15 A6-16 A6-15pipe 25 0.014 939.372 937.53 Circular 7.36 0.25 0.75 1 0.9 - - - - -- - A6-15over 25 0.014 941.372 939.4 Trapezoidal - - - - 0 0.3 - - -

A6-16 A6-12 A6-16pipe 5.5 0.014 937.53 937.5 Circular 0.54545 0.25 0.75 1 0.9 - - - - -- - A6-16over 5.5 0.014 939.4 939 Trapezoidal - - - - 20 2 - - -

A6-12 Outlet A6-12chan 175 0.014 937.5 930.8 Natural 3.82857 - - - 2 - - 0.06 0.03 2

18/12/2006 5:42 PM

Hydraulic Network DataCatchment B

Culvert Size

Width Channel DepthChannel

Depthm m m % m m m m

B1-1 B1-3 B1-1pipe 12.1 0.014 956.3 955.67 Circular 5.21 0.25 0.75 1 0.45 - - - - -- - B1-1over 12.1 0.014 957.47 956.62 Trapezoidal 7.02 - - - 0.5 20 0.5 - - -

B1-3 B1-4 B1-3box 6.6 0.014 955.67 955.3 Rectangle - 0.25 0.75 1 0.6 - - - - -- - B1-3over 6.6 0.014 956.87 956.5 Trapezoidal - - - - - 20 0.5 - - -

B1-4 B1-9 B1-4trap 106.34 0.014 955.3 949.5 Natural 5.45 - - - - - - 0.05 0.015 2B1-9 B1-6 - 137.74 0.014 950 943.5 Trapezoidal - - - - - 20 1 - - -B1-9 B1-2 B1-9BOX 103.24 0.014 949.5 944.12 Rectangle - 0.25 0.75 1 0.5 - - - - -B1-2 B1-6 B1-2culv 34.5 0.014 944.12 941.4 Circular 7.88 0.25 0.75 1 0.75 - - - - -B1-6 B1-7 B1-6culv 17.01 0.014 941.4 940.81 Circular 3.47 0.25 0.75 1 0.75 - - - - -

- - B1-6over 17.01 0.014 943.5 942.68 Trapezoidal 4.82 - - - - 20 0.5 - - -B1-7 B1-10 B1-7pipe 7.83 0.014 940.81 940.45 Circular 4.60 0.25 0.75 1 0.75 - - - - -

- - B1-7over 7.83 0.014 942.66 942.35 Trapezoidal 3.96 - - - - 10 0.5 - - -B1-10 B1-11 B1-10PIPE 30 0.014 940.45 939.77 Circular - 0.25 0.75 1 0.9 - - - - -

- - B1-10over 30 0.014 942.35 941.92 Trapezoidal - - - - - 20 0.5 - - -B1-11 B1-8 b1-11pipe 52.84 0.014 939.77 937.45 Circular - 0.25 0.75 1 0.9 - - - - -

- - b1-11over 52.84 0.014 941.92 938.35 Trapezoidal - - - - - 20 0.5 - - -B1-8 B1-4/B2-3 B1-8chan 181 0.014 937.45 922 Natural 7.90 - - - - - - 0.06 0.03 2B2-1 B2-4 B2-1culv 12 0.014 948.8 948.47 Circular 2.75 0.25 0.75 1 0.9 - - - - -

- - B2-1over 12 0.014 950 949.61 Trapezoidal - - - - - 20 0.5 - - -B2-4 B2-7 B2-4culv 3.62 0.014 948.47 948.38 Circular 2.49 0.25 0.75 1 0.9 - - - - -

- - B2-4over 3.62 0.014 949.61 948.6 Trapezoidal 27.90 - - - - 20 0.5 - - -B2-7 B2-8 B2-7chan 19.87 0.014 948.38 947.6 Natural 3.93 - - - - - - 0.06 0.03 1.3B2-8 B2-9 B2-8culv 20.5 0.014 947.6 947.26 Circular 1.66 0.25 0.75 1 0.9 - - - - -

- - B2-8over 20.5 0.014 948.75 947.5 Trapezoidal 6.10 - - - - 20 0.5 - - -B2-9 B2-10 B2-9chan 15.034 0.014 947.26 946.25 Natural 6.72 - - - - - - 0.06 0.03 1

B2-10 B2-11 B2-10culv 39.7 0.014 946.25 943.08 Circular 7.98 0.25 0.75 1 0.9 - - - - -- - B2-10over 52.833 0.014 946.8 944 Trapezoidal 5.30 - - - - 20 0.5 - - -

B2-11 B2-2 B2-11chan 63.24 0.014 943.08 940.9 Natural 3.45 - - - - - - 0.06 0.03 2B2-2 B2-5 B2-2culv 13 0.014 940.7 940.35 Circular 2.69 0.25 0.75 1 0.9 - - - - -

- - B2-2over 13 0.014 942.22 941.8 Trapezoidal - - - - - 20 0.5 - - -B2-5 B2-6 B2-5pipe 198 0.014 940.35 932.8 Circular 3.57 0.25 0.75 1 1.2 - - - - -

- - B2-5over 198 0.02 941.8 934.1 Trapezoidal - - - - - 20 1 - - -B2-6 B1-4/B2-3 B2-6chan 249 0.014 932.9 922 Natural 4.38 - - - - - - 0.06 0.03 3

B1-4/B2-3 B3-1 B1-4chan 387 0.014 922 891.5 Natural 7.88 - - - - - - 0.06 0.03 2B3-1 B3-2 B3-1chan 160 0.014 891.5 868 Natural 14.69 - - - - - - 0.06 0.03 2B3-2 Outfall Dummy 10 0.014 868 866.25 Natural 17.50 - - - - - - 0.06 0.03 2

US Node DS NodeMulti Link

Name


LengthRoughness

Upstream IL

Downstream IL Shape

Conduit Slope

Natural Channel

Entrance Loss

Exit Loss

Number of Barrels

Left/Right Bank -

Mannings n

Channel Mannings

n

Culvert Details

18/12/2006 5:42 PM

Hydraulic Network DataCatchment C

Culvert Size



C1-1 C1-2 C1-1culv 10.5 0.014 969.14 966.8 Circular 22.2857 0.25 0.75 1 0.3 - - - - -- - C1-1over 10.5 0.014 969.54 968.1 Trapezoidal 13.7143 - - - - 20 0.5 - - -

C1-2 C1-3 C1-2trap 95 0.03 966.8 948.63 Trapezoidal 19.2632 - - - - 0.6 0.3 - - -C1-3 C1-4 C1-3culv 10.84 0.014 948.63 948 Circular 5.81181 0.25 0.75 1 0.9 - - - - -

- - C1-3over 10.84 0.014 950.13 949.9 Trapezoidal 2.12177 - - - - 20 0.5 - - -C1-4 C1-5 c1-4chan 174.3 0.014 948 937.4 Natural 6.08147 - - - - - - 0.06 0.03 2C1-5 C1-6 C1-5culv 29.04 0.014 937.4 936.2 Circular 4.13223 0.25 0.75 1 0.6 - - - - -

- - C1-5over 29.04 0.014 938.8 937.1 Trapezoidal 5.85399 - - - - 20 0.5 - - -C1-6 C1-7 c1-6chan 84.65 0.014 936.2 933 Natural 3.78027 - - - - - - 0.06 0.03 2C1-7 C1-8 C1-7trap 56.4 0.045 933 930.7 Trapezoidal 3.09556 - - - - 1.4 1.3 - - -C1-8 C1-10 C1-8culv 15.5 0.014 930.7 929.1 Circular 10.3226 0.25 0.75 1 1.25 - - - - -

- - C1-8over 15.5 0.014 932.7 932.6 Trapezoidal 0.64516 - - - - 20 0.5 - - -C1-9 C1-10 C1-9culv 14.7 0.014 931.67 929.1 Circular 17.483 0.25 0.75 1 0.45 - - - - -

- - C1-9over 14.7 0.014 932.7 932.6 Trapezoidal - - - - - 20 0.5 - - -C1-10 C1-11 C1-10chan 229.2 - 929.1 907 Natural - - - - - - - 0.06 0.03 1C1-11 C1-12 c1open6 229.2 0.014 907 878.9 Natural 12.26 - - - - - - 0.06 0.03 2C2-1 C2-2 C2-1chan 200 0.014 947.07 938.5 Natural 4.285 0 0 1 1 - - 0.06 0.03 1C2-2 C2-3 C2-2chan 49.8 0.014 938.5 934.706 Natural 7.61044 - - - - - - 0.06 0.03 1C2-3 C2-4 C2-3culv 9.78 0.014 934.71 934.23 Circular 4.90798 1 1 2 0.45 - - - - -

- - C2-3over 9.78 0.014 936 935.9 Trapezoidal 1.02249 - - - - 20 0.5 - - -C2-4 C2-7 C2-4Chan 18.28 0.02 934.23 934 Natural 1.25821 0 0 1 1.5 - - 0.06 0.03 1.5C2-7 C2-8 C2-7chan 49.71 0.014 934 932 Natural 4.02334 - - - - - - 0.06 0.03 1.5C2-8 C2-5 C2-8chan 175.28 0.014 932 925.612 Natural 3.64445 - - - - - - 0.06 0.03 1.5C2-5 C2-6 C2-5chan 192.72 0.014 925.612 887.18 Natural 19.9419 - - - - - - 0.06 0.03 2C2-6 C1-12 C2-6chan 38.3 0.014 887.18 878.9 Natural 21.6188 - - - - - - 0.06 0.03 2C1-12 C-3A C1-12chan 84.21 - 878.9 872.5 Natural - - - - - - - 0.06 0.03 2.5C-3A Outlet dummy 10 - 872.5 871.74 Natural - - - - - - - 0.06 0.03 1.5


Name


LengthRoughness

Upstream IL

Downstream IL Shape

Conduit Slope

Natural Channel

Entrance Loss

Exit Loss

Number of Barrels

Left/Right Bank -

Mannings n

Channel Mannings

n

Culvert Details

18/12/2006 5:42 PM

Hydraulic Network DataCatchment D

Culvert Size



D-1 D-2 D-1culv 12 0.014 936.64 936.5 Circular 1.16667 0.25 0.75 1 0.45 - - - - -- - D-1over 12 0.011 937.84 937.3 Trapezoidal 4.5 - - - - 30 0.5 - - -

D-2 D-4 D-2pipe 6 0.014 936.5 936.37 Circular 2.16667 0.25 0.75 1 0.45 - - - - -- - D-2over 6 0.014 937.3 936.97 Trapezoidal - - - - - 20 0.5 - - -

D-4 D-5 D-4chan 44.8 0.035 936.37 934.2 Natural 4.84375 - - - - - - 0.06 0.03 0.45D-5 D-3 D-5chan 355 0.014 934.2 885 Natural 14 - - - - - - 0.06 0.03 2D-3 OUTLET dummy 100 0.014 885 884 Natural 1 - - - - - - 0.06 0.03 2


Name


LengthRoughness

Upstream IL

Downstream IL Shape

Conduit Slope

Natural Channel

Entrance Loss

Exit Loss

Number of Barrels

Left/Right Bank -

Mannings n

Channel Mannings

n

Culvert Details

18/12/2006 5:42 PM


Culvert Size



E2-1 E2-3 E2-1culv 9 0.014 910.9 909.6 Circular 14.44 0.25 0.75 1 0.375 - - - - -- - E2-1over 9 0.014 912 911.5 Tapezoidal 5.56 - - - - 20 0.5 - - -

E2-3 E2-4 E2-3culv 11 0.014 909.6 908.1 Circular 13.64 0.25 0.75 1 0.75 - - - - -- - E2-3over 11 0.014 911.5 911.3 Tapezoidal 1.82 - - - - 20 0.5 - - -

E2-4 E2-2 E2-4pipe 39.4 0.014 908.1 907.1 Circular 2.54 0.25 0.75 1 0.75 - - - - -- - E2-4over 39.4 0.014 911.3 908 Tapezoidal 8.38 - - - - 20 0.5 - - -

E2-2 J.E-1 E2-2trap 47 0.035 907.1 904 Tapezoidal 6.60 - - - - 0.8 0.5 - - -E1-1 J1 E1-1chan1 43.7 0.014 940.67 937.86 Tapezoidal 6.43 - - - - 0 0.3 - - -E1-2 J1 E1-2chan 25.2 0.014 940.84 937.9 Tapezoidal 11.67 - - - - 0 0.3 - - -J1 E1-4 J1-pipe 56.6 0.014 937.86 935 Circular 5.05 0.25 0.75 1 0.3 - - - - -J1 E1-8 - 40 0.03 938.7 935.17 Tapezoidal 8.83 - - - - 0 1.7 - - -

E1-8 E1-8a E1-8chan 36.225 - 935.17 933.41 Natural 4.86 - - - - - - 0.06 0.03 2E1-8a E1-9 E1-8achan 28.8 - 933.41 933.065 Natural 1.20 - - - - - - 0.06 0.03 2E1-9 E1-9a E1-9chan 18.056 - 933.065 932.21 Natural 4.74 - - - - - - 0.06 0.03 2

E1-9a E1-10 E1-9achan 18.018 - 932.21 931.263 Natural 5.26 - - - - - - 0.06 0.03 2E1-10 E1-10a E1-10chan 17.43 - 931.263 930.27 Natural 5.70 - - - - - - 0.06 0.03 2E1-10a E1-10b E1-10achan 19.22 - 930.27 929.2 Natural 5.57 - - - - - - 0.06 0.03 2E1-10b E1-10c E1-10bchan 21 - 929.2 928.114 Natural 5.17 - - - - - - 0.06 0.03 2E1-10c E1-11 E1-10Cchan 21.2 - 928.114 926.642 Natural 6.94 - - - - - - 0.06 0.03 2E1-11 E1-12 E1-11chan 35.7 - 926.64 923.17 Natural 9.72 - - - - - - 0.06 0.03 2E1-4 E1-9 - 40 0.025 935.95 933.065 Tapezoidal 7.21 - - - - 20 1 - - -E1-4 E1-5 E1-4pipe 43.3 0.014 935 932.8 Circular 5.08 0.25 0.75 1 0.375 - - - - -

- - E1-4chan 43.3 - 935.8 933.71 Natural 4.83 - - - - - - 0.014 0.014 0.15E1-5 E1-5a E1-5pipe 25.16 0.014 932.8 931.69 Circular 4.41 0.25 0.75 1 0.45 - - - - -E1-5 E1-5c - 118 - 933.71 928.89 Natural 4.08 - - - - - - 0.014 0.014 0.15E1-5 E1-10b - 10 0.025 933.86 929.2 Tapezoidal 46.60 - - - - 20 1 - - -

E1-5a E1-5b E1-5apipe 50.43 0.014 931.59 929.38 Circular 4.38 0.25 0.75 1 0.45 - - - - -E1-5b E1-5c E1-5bpipe 42.85 0.014 929.26 927.8 Circular 3.41 0.25 0.75 1 0.525 - - - - -E1-5c E1-5d E1-5cpipe 43.56 0.014 927.76 926.5 Circular 2.89 0.25 0.75 1 0.525 - - - - -E1-5c E1-6 - 48.7 - 928.89 927.3 Natural 3.26 - - - - - - 0.014 0.014 0.15E1-5c E1-11 - 10 0.014 929.04 926.64 Tapezoidal 24.00 - - - - 20 1 - - -E1-5d E1-6 E1-5dpipe 5.15 0.014 926.5 926.4 Circular 1.94 0.25 0.75 1 0.525 - - - - -E1-6 E1-12 E1-6chan 29.4 0.014 926.4 923.17 Tapezoidal 10.99 - - - - 0 0.3 - - -

E1-12 E1-13 E1-6chan 23.24 0.014 923.17 922.2 Natural 4.17 - - - - - - 0.06 0.015 2E1-7b E1-13 - 27.9 0.014 926.44 922.2 Tapezoidal 15.20 - - - - 2 1 - - -E1-13 E1-13a E1-6chan 8.1 0.014 922.2 921.5 Natural 8.64 - - - - - - 0.06 0.015 2E1-13a E1-13b E1-13Apipe 3.8 0.014 921.5 921.41 Circular 2.37 0.25 0.75 1 0.3 - - - - -

- - E1-13Aover 3.8 0.014 922.156 922.143 Tapezoidal 0.34 - - - - 10 1 - - -E1-13b E1-13c E1-13Bchan 19.3 - 921.41 920.81 Natural 3.11 - - - - - - 0.06 0.015 2E1-13c E1-14 E1-13Cpipe 20.5 0.014 920.81 920.6 Circular 1.02 0.25 0.75 1 0.3 - - - - -

Natural Channel

Entrance Loss

Exit Loss

Number of Barrels

Left/Right Bank -

Mannings n

Channel Mannings

n


Multi Link Name


LengthRoughness

Upstream IL

Downstream IL Shape

Conduit Slope

18/12/2006 5:42 PM


Culvert Size



Natural Channel

Entrance Loss

Exit Loss

Number of Barrels

Left/Right Bank -

Mannings n

Channel Mannings

n


Multi Link Name


LengthRoughness

Upstream IL

Downstream IL Shape

Conduit Slope

- - E1-13Cover 20.513 0.014 921.17 921.1 Tapezoidal 0.34 - - - - 10 1 - - -E1-14 E1-16 - 90.4 - 920.6 916.97 Natural 4.02 - - - - - - 0.06 0.03 2E1-18 E1-16 - 58.5 0.014 923.53 916.97 Tapezoidal 11.21 - - - - 2 1 - - -E1-16 E1-19 - 72.95 - 916.97 913.65 Natural 4.55 - - - - - - 0.06 0.03 2E1-19 J.E-1 - 193.1 - 913.65 904 Natural 5.00 - - - - - - 0.06 0.03 2J.E-1 E1-21 J.E-1chan 453 0.014 904 856 Natural 10.60 - - - - - - 0.06 0.03 2E1-21 J.E-2 dummy1 98 0.014 856 844 Natural 12.24 - - - - - - 0.06 0.03 2E3-1 J.E-2 E3-1chan 91 0.014 882 844 Natural 41.76 - - - - - - 0.06 0.03 2J.E-2 OUTLET dummy3 100 0.014 844 843 Natural 1.00 - - - - - - 0.06 0.03 2

18/12/2006 5:42 PM

Hydraulic Network DataCatchment F

Culvert Size



F1-12 F1-1 F1-12culv 6.342 0.014 934.62 934.49 Circular 2.04983 0.25 0.75 1 0.525 - - - - -- - F1-12over 6.342 0.014 935.51 935.5 Trapezoidal 0.15768 - - - - 20 0.5 - - -

F1-1 F1-5 F1-1culv 8.65 0.014 934.49 933.86 Circular 7.28324 0.25 0.75 1 0.525 - - - - -- - F1-1over 8.65 0.014 935.52 935.47 Trapezoidal 0.57803 - - - - 20 0.5 - - -

F1-5 F1-2 F1-5trap 44.39 0.022 933.86 931.92 Natural 4.37055 - - - - - - 0.06 0.03 1.4F1-2 F1-13 F1-2culv 47.11 0.014 931.92 930.21 Circular 3.6298 0.25 0.75 1 0.6 - - - - -

- - F1-2over 92.4 0.014 932.9 931.38 Trapezoidal - - - - - 20 0.5 - - -F1-13 F1-14 F1-13culv 10.68 0.014 930.21 929.63 Circular 5.43071 0.25 0.75 1 0.6 - - - - -



- - F1-15over 59.727 0.014 928.9 927.05 Trapezoidal 3.09743 - - - - 20 0.5 - - -F1-6 F1-7 F1-6chan 117.539 0.025 926.12 922.576 Natural 3.01517 - - - - - - 0.06 0.03 1.48F1-7 F1-8 F1-7chan 124.075 0.014 922.576 916.738 Natural 4.70522 - - - - - - 0.06 0.03 1F1-8 F1-9 F1-8chan 59.42 0.014 916.738 914.265 Natural 4.1619 0.25 0.75 3 1 - - 0.06 0.015 1F1-9 F1-10 F1-9pipe 37.35 0.014 914.265 912.15 Circular 5.66265 0.25 0.75 3 0.525 - - - - -

- - F1-9over 37.35 0.014 915.177 914.35 Trapezoidal 2.21419 - - - - 20 0.5 - - -F1-10 F1-3 F1-10culv 17.454 0.014 912.15 911.37 Circular 4.46889 0.25 0.75 1 1.2 - - - - -

- - F1-10over 23 0.014 914.61 914 Trapezoidal 2.65217 - - - - 20 0.07713 - - -F1-3 F1-11 F1-3chan 403.356 0.014 911.37 890.931 Natural 5.06724 - - - - - - 0.06 0.03 1F1-11 F1-4/F2-2 F1-11chan 368.788 0.014 890.31 862 Natural 7.6765 - - - - - - 0.06 0.03 1F2-1 F1-4/F2-2 F2-1chan 255 0.014 897 862 Natural 13.7255 - - - - - - 0.06 0.03 1

F1-4/F2-2 F1-5/F3-2 F1-4chan 245 0.014 862 851 Natural 4.4898 - - - - - - 0.06 0.03 2F3-1 F1-5/F3-2 F3-1chan 390 0.014 904.5 851 Natural 13.718 - - - - - - 0.06 0.03 2

F1-5/F3-2 OUTLET dummy 100 0.014 851 850 Natural 1 - - - - - - 0.06 0.03 2


Name


LengthRoughness

Upstream IL

Downstream IL Shape

Conduit Slope

Natural Channel

Entrance Loss

Exit Loss

Number of Barrels

Left Mannings n

Channel Mannings

n

Culvert Details

18/12/2006 5:42 PM

SWMM Results20, 50, 100 year and PMF

Water Depth

ElevationWater Depth

Elevation Water Depth ElevationWater Depth

Elevation

m RL m AHD m RL m AHD m RL m AHD m RL m AHDA1-3 1.31 952.01 1.31 952.01 0.69 948.29 1.56 950.26A1-4 1.08 951.18 1.08 951.18 1.32 952.02 1.39 952.09A1-1 1.20 949.90 1.24 949.94 1.23 951.33 1.74 951.84A1-6 0.84 949.41 0.94 949.50 1.27 949.97 1.63 950.20A1-2 0.59 948.19 0.65 948.25 1.07 949.63 1.39 948.99J.A-1 1.40 948.20 1.45 948.25 1.50 948.30 2.20 949.00A2-1 0.57 965.07 0.58 965.08 0.58 965.08 0.73 965.23A2-4 0.76 964.46 0.81 964.51 0.84 964.54 1.27 964.97A2-5 0.42 962.78 0.46 962.82 0.50 962.86 0.83 963.19A2-2 1.08 950.08 1.09 950.09 1.10 950.10 1.36 950.36A2-3 0.37 948.97 0.43 949.03 0.47 949.07 1.55 950.15

A2-3A 1.01 948.31 1.05 948.35 1.07 948.37 1.44 948.74A2-3B 0.50 946.60 0.54 946.64 0.57 946.67 1.13 947.23A1-5 1.30 946.60 1.34 946.64 1.37 946.67 1.93 947.23A3-1 1.55 946.15 1.61 946.21 1.50 946.10 2.37 946.97A3-2 0.55 954.05 0.55 954.05 0.56 954.06 0.68 954.18A3-4 0.19 952.99 0.21 953.01 0.22 953.02 0.32 953.12J.A-3 1.39 945.69 1.48 945.78 1.57 945.87 2.64 946.94A3-5 0.70 942.40 0.79 942.49 0.86 942.56 1.81 943.51

A3-3/A4-1 0.31 932.65 0.37 932.71 0.42 932.76 1.16 933.50A2 (A2-6) 0.43 937.93 0.46 937.96 0.48 937.98 0.82 938.32

A5-1/A6-13 0.64 931.44 0.75 931.55 0.85 931.65 1.99 932.79A7-1 0.99 930.99 1.20 931.20 1.43 931.43 1.99 931.99A7-2 0.52 928.85 0.62 928.95 0.71 929.04 0.70 929.03

A8-1/A9-1 0.66 923.19 0.77 923.30 0.88 923.41 1.10 923.63A10-1 1.48 903.48 1.65 903.65 1.80 903.80 2.64 904.64A11-1 0.49 900.81 0.54 900.86 0.59 900.91 1.24 901.56A10-2 2.26 888.26 2.29 888.29 2.51 888.51 4.06 890.06

0 2.00 884.00 2.29 884.29 2.50 884.50 4.05 886.05A6-1 0.49 949.24 0.74 949.49 0.86 949.61 0.89 949.64A6-2 0.33 947.86 0.43 947.96 0.50 948.03 1.29 948.82A6-3 0.11 947.74 0.12 947.75 0.13 947.76 1.22 948.85A6-7 0.17 955.32 0.19 955.34 0.21 955.36 0.88 956.03A6-8 0.19 953.79 0.25 953.85 0.32 953.92 1.24 954.84A6-4 0.27 950.72 0.08 950.53 0.09 950.54 0.92 951.37A6-5 0.18 950.44 0.16 950.42 0.15 950.41 0.92 951.18A6-6 0.29 948.87 0.90 949.48 0.38 948.96 0.77 949.35A6-9 0.93 947.93 0.99 947.99 1.13 948.13 1.70 948.70A6-10 0.45 947.19 0.50 947.24 0.57 947.31 1.72 948.46A6-11 0.60 946.62 0.59 946.61 0.63 946.65 2.39 948.41A6-14 0.49 944.19 0.65 944.35 0.90 944.60 4.29 947.99A6-15 1.42 940.79 1.82 941.19 2.04 941.41 2.41 941.78A6-16 2.00 939.53 2.01 939.54 1.91 939.44 2.06 939.59A6-12 0.38 937.88 0.41 937.91 0.44 937.94 2.00 939.50Outlet 2.70 933.50 3.10 933.90 3.50 934.30 8.40 939.20

PMF20 Year ARI

Node

100 Year ARI50 Year ARI

20/12/2006 9:32 AM


Water Depth



Elevation

m RL m AHD m RL m AHD m RL m AHD m RL m AHDB2-1 1.27 950.07 1.29 950.09 1.30 950.10 1.49 950.29B2-4 1.17 949.64 1.18 949.65 1.19 949.66 1.33 949.80B2-7 1.09 949.47 1.12 949.50 1.15 949.53 1.42 949.80B2-8 1.19 948.79 1.20 948.80 1.21 948.81 1.37 948.97B2-9 0.71 947.97 0.82 948.08 0.91 948.17 1.27 948.53B2-10 0.58 946.83 0.59 946.84 0.61 946.86 0.79 947.04B2-11 1.26 944.34 1.52 944.60 1.67 944.75 2.14 945.22B2-2 1.65 942.35 1.66 942.36 1.66 942.36 1.89 942.59B2-5 1.58 941.88 1.62 941.92 1.66 941.96 2.16 942.46B2-6 0.63 933.43 0.67 933.47 0.72 933.52 1.36 934.16B1-1 1.21 957.51 1.21 957.51 1.22 957.52 1.29 957.59B1-3 1.24 956.91 1.25 956.92 1.25 956.92 1.36 957.03B1-4 0.27 955.57 0.29 955.59 0.31 955.61 0.58 955.88B1-9 0.52 950.02 0.53 950.03 0.54 950.04 0.63 950.13B1-2 0.60 944.72 0.61 944.73 0.61 944.73 0.66 944.78B1-6 2.16 943.56 2.16 943.56 2.17 943.57 2.29 943.69B1-7 1.98 942.79 1.97 942.78 1.99 942.80 2.15 942.96B1-10 1.95 942.40 1.98 942.43 2.04 942.49 2.24 942.69B1-11 1.00 940.77 1.68 941.45 2.20 941.97 2.35 942.12B1-8 0.85 938.30 0.84 938.29 0.89 938.34 1.41 938.86

B1-4/B2-3 0.84 922.84 0.93 922.93 1.02 923.02 2.39 924.39B3-1 1.11 892.61 1.19 892.69 1.27 892.77 2.46 893.96B3-2 1.16 869.16 1.25 869.25 1.32 869.32 2.57 870.57

Outfall 1.16 867.41 1.25 867.50 1.32 867.57 2.57 868.82

PMF20 Year ARI

Node


20/12/2006 9:33 AM


Water Depth



Elevation

m RL m AHD m RL m AHD m RL m AHD m RL m AHDC1-1 0.42 969.56 0.42 969.56 0.42 969.56 0.46 969.60C1-2 0.09 966.89 0.08 966.88 0.09 966.89 0.20 967.00C1-3 1.18 949.81 1.51 950.14 1.52 950.15 1.66 950.29C1-4 0.34 948.34 0.37 948.37 0.39 948.39 0.79 948.79C1-5 1.46 938.86 1.48 938.88 1.49 938.89 1.70 939.10C1-6 0.49 936.69 0.51 936.71 0.54 936.74 0.92 937.12C1-7 0.57 933.57 0.64 933.64 0.65 933.65 1.32 934.32C1-8 1.23 931.93 2.05 932.75 2.06 932.76 2.31 933.01C1-9 1.04 932.71 1.05 932.72 1.05 932.72 1.15 932.82C1-10 0.46 929.56 0.57 929.67 0.62 929.72 1.33 930.43C1-11 0.88 907.88 0.94 907.94 1.02 908.02 1.98 908.98C2-1 0.22 947.29 0.22 947.29 0.22 947.29 0.46 947.53C2-2 0.28 938.78 0.31 938.81 0.33 938.83 0.64 939.14C2-3 1.33 936.03 1.34 936.04 1.35 936.05 1.52 936.23C2-4 0.34 934.56 0.39 934.61 0.43 934.66 0.93 935.16C2-7 0.22 934.22 0.26 934.26 0.28 934.28 0.57 934.57C2-8 0.22 932.22 0.24 932.24 0.27 932.27 0.58 932.58C2-5 0.19 925.80 0.22 925.83 0.24 925.86 0.60 926.21C2-6 1.35 888.53 1.39 888.57 1.41 888.59 1.72 888.90C1-12 0.84 879.74 1.00 879.90 1.12 880.02 2.78 881.68C-3A 0.86 873.36 1.01 873.51 1.14 873.64 2.82 875.32Outlet 0.86 872.60 1.01 872.75 1.14 872.88 2.81 874.55

PMF20 Year ARI

Node


20/12/2006 9:34 AM


Water Depth



Elevation

m RL m AHD m RL m AHD m RL m AHD m RL m AHDD-1 1.22 937.86 1.22 937.86 1.22 937.86 1.27 937.91D-2 0.84 937.34 0.84 937.34 0.85 937.35 0.91 937.41D-4 0.31 936.68 0.35 936.72 0.38 936.75 0.89 937.26D-5 0.26 934.46 0.28 934.48 0.30 934.50 0.61 934.81D-3 0.74 885.74 0.81 885.81 0.87 885.87 1.68 886.68

OUTLET 0.49 884.49 0.54 884.54 0.58 884.58 1.21 885.21

PMF20 Year ARI

Node


20/12/2006 9:34 AM


Water Depth



Elevation

m RL m AHD m RL m AHD m RL m AHD m RL m AHDE1-1 0.17 940.84 0.19 940.86 0.20 940.87 2.00 942.67E1-2 0.13 940.97 0.14 940.98 0.15 940.99 0.27 941.11J1 1.05 938.91 1.08 938.94 1.09 938.95 1.28 939.14

E1-4 0.95 935.95 0.95 935.95 0.95 935.95 1.02 936.02E1-8 0.06 935.23 0.07 935.24 0.16 935.33 0.28 935.45E1-8a 0.17 933.58 0.19 933.60 0.20 933.61 0.41 933.82E1-9 0.09 933.16 0.13 933.19 0.16 933.22 0.41 933.47E1-9a 0.06 932.27 0.08 932.29 0.09 932.30 0.36 932.57E1-10 0.06 931.32 0.07 931.33 0.07 931.34 0.33 931.60

E1-10a 0.15 930.42 0.18 930.45 0.19 930.46 0.51 930.78E1-5 1.06 933.86 1.05 933.85 1.06 933.86 1.07 933.87E1-5a 0.81 932.40 0.82 932.41 0.82 932.41 0.82 932.41E1-5b 0.75 930.01 0.76 930.02 0.76 930.02 0.83 930.09E1-5c 1.27 929.03 1.28 929.04 1.28 929.04 1.29 929.05E1-5d 1.29 927.79 1.28 927.78 1.28 927.78 1.28 927.78E1-6 0.24 926.64 0.26 926.66 0.26 926.66 0.26 926.66

E1-10c 0.27 928.38 0.30 928.41 0.31 928.43 0.66 928.78E1-11 0.26 926.90 0.29 926.93 0.31 926.95 0.66 927.30E1-12 0.35 923.52 0.38 923.55 0.40 923.57 0.68 923.85E1-7b 0.02 926.46 0.03 926.47 0.03 926.47 0.06 926.50E1-13 0.34 922.54 0.36 922.56 0.38 922.58 0.60 922.80

E1-13a 0.77 922.27 0.80 922.30 0.81 922.31 0.98 922.48E1-13b 0.68 922.09 0.71 922.12 0.75 922.16 1.00 922.41E1-13c 0.51 921.32 0.54 921.35 0.57 921.38 1.11 921.92E1-14 0.65 921.25 0.71 921.31 0.76 921.36 1.33 921.93E1-18 0.04 923.57 0.05 923.58 0.05 923.58 0.18 923.71E1-16 0.20 917.17 0.23 917.20 0.25 917.22 0.59 917.56E1-19 0.35 914.00 0.39 914.04 0.43 914.08 0.88 914.53E2-1 0.69 911.59 1.10 912.00 1.11 912.01 1.17 912.07E2-3 0.14 909.74 0.15 909.75 0.17 909.77 1.79 911.39E2-4 0.21 908.31 0.23 908.33 0.25 908.35 2.23 910.33E2-2 0.39 907.49 0.42 907.52 0.49 907.59 1.40 908.50J.E-1 0.56 904.56 0.62 904.62 0.68 904.68 1.31 905.31E1-21 0.66 856.66 0.73 856.73 0.79 856.79 1.55 857.55E3-1 0.26 882.26 0.27 882.27 0.29 882.29 0.55 882.55J.E-2 1.35 845.35 1.48 845.48 1.59 845.59 2.00 846.00

OUTLET 0.99 843.99 1.10 844.10 1.19 844.19 1.52 844.52E1-10b 0.21 929.41 0.24 929.44 0.25 929.45 0.59 929.79

PMF20 Year ARI

Node


20/12/2006 9:34 AM


Water Depth



Elevation

m RL m AHD m RL m AHD m RL m AHD m RL m AHDF1-12 0.98 935.60 0.98 935.60 0.99 935.61 1.43 936.05F1-1 1.07 935.56 1.07 935.56 1.08 935.57 1.29 935.78F1-5 0.35 934.21 0.36 934.22 0.36 934.22 0.54 934.40F1-2 1.06 932.98 1.07 932.99 1.08 933.00 1.28 933.20F1-13 1.21 931.42 1.22 931.43 1.23 931.44 1.33 931.54F1-14 1.13 930.76 1.15 930.78 1.16 930.79 1.33 930.96F1-15 2.07 928.97 2.10 929.00 2.11 929.01 2.32 929.22F1-6 0.51 926.63 0.61 926.73 0.69 926.81 1.14 927.26F1-7 0.46 923.04 0.53 923.10 0.62 923.19 1.21 923.78F1-8 0.57 917.31 0.61 917.35 0.64 917.38 1.26 918.00F1-9 1.05 915.31 1.06 915.32 1.07 915.33 1.28 915.54F1-10 2.49 914.64 2.53 914.68 2.55 914.70 2.85 915.00F1-3 0.48 911.85 0.54 911.91 0.60 911.97 1.15 912.52F1-11 0.94 890.73 1.01 890.80 1.08 890.87 1.79 891.58F2-1 0.37 897.37 0.41 897.41 0.45 897.45 0.95 897.95

F1-4/F2-2 0.65 862.65 0.71 862.71 0.86 862.86 2.14 864.14F3-1 0.26 904.76 0.28 904.78 0.30 904.80 0.59 905.09

F1-5/F3-2 1.23 852.23 1.32 852.32 1.55 852.55 3.18 854.18OUTLET 0.88 850.88 0.96 850.96 1.18 851.18 2.80 852.80

PMF20 Year ARI

Node


20/12/2006 9:35 AM

Appendix F Flood Damages

South Leura Floodplain Risk Management Study & Plan - 29 April 2008 Page F

Properties Impacted by 100 Year Flood and PMF

100 Year ARI Flood Event PMF Flood Event

Property located in 100 Year ARI Flood Extent (Y/N?

Property located in PMF Flood Extent (Y/N?)

A12 Commonwealth Street LEURA NSW 2780

Y Y


Y Y


Y Y


Y Y

A28-30 Commonwealth Street LEURA NSW 2780

Y Y

A32-34 Commonwealth Street LEURA NSW 2780

Y Y


Y Y

A20-22 Coomassie Street KATOOMBA NSW 2780

Y Y

A37 Govett Street KATOOMBA NSW 2780

Y Y


Y Y


Y Y


Y Y


Y Y

A58 Govett St KATOOMBA NSW 2780

n Y

A60 Govett St KATOOMBA NSW 2780

n Y


Y Y


Y Y

A70-72 Govett Street KATOOMBA NSW 2780

Y Y


Y Y


Y Y


Y Y


Y Y

A7 Kanimbla Street LEURA NSW 2780

N Y

A12-18 Kanimbla Street LEURA NSW 2780

Y Y


Y Y


Y Y


Y Y

A25 Kanimbla Street KATOOMBA NSW 2780

Y Y

A4-10 Kanimbla St KATOOMBA NSW 2780

N Y


Y Y


Y Y


Y Y


N Y


Y Y

Catchment Property

18/12/2006 7:12 PM


Property located in 100 Year ARI Flood Extent (Y/N?)


Catchment Property


Y Y

A26 Magdala Street KATOOMBA NSW 2780

N Y

A48 Megalong St, KATOOMBA NSW 2780

Y Y

A52 Megalong St KATOOMBA NSW 2780

n Y


n Y


n Y


n Y


n Y

A62 Megalong Street KATOOMBA NSW 2780

Y Y

A64 Megalong Street KATOOMBA NSW 2780

Y Y

A66-72 Megalong St KATOOMBA NSW 2780

n Y

A78 Megalong Street LEURA NSW 2780

Y Y


Y Y


Y Y


Y Y


Y Y


Y Y


Y Y


Y Y

A16-18 Murray Street LEURA NSW 2780

Y Y

A39 Murray Street LEURA NSW 2780

Y Y


Y Y


Y Y


Y Y


Y Y

A8-14 Murray Street LEURA NSW 2780

Y Y

A9-11 Wascoe Street LEURA NSW 2780

Y Y

A39 Wilson Street KATOOMBA NSW 2780

Y Y


Y Y


n Y


Y Y

A46-56 Wilson Street KATOOMBA NSW 2780

Y Y


Y Y


Y Y

18/12/2006 7:12 PM




Catchment Property


Y Y


Y Y


Y Y


Y Y

A53-59 York Street KATOOMBA NSW 2780 (check correct road)

N Y

APeter Carroll Field 1-9 Clarence Street KATOOMBA

Y Y

B7 Abbey Street LEURA NSW 2780

Y Y


Y Y


Y Y


Y Y


Y Y


Y Y


Y Y


Y Y


Y Y


Y Y


Y Y


Y Y


Y Y


Y Y


Y Y


N Y

B4 Craigend Street LEURA NSW 2780

N Y


Y Y


N Y


Y Y

B7a Craigend Street LEURA NSW 2780

N Y


Y Y

B37-39 Craigend Street LEURA NSW 2780

Y Y

B40-42 Craigend Street LEURA NSW 2780

Y Y


N Y

B59 Grose Street LEURA NSW 2780

Y Y

B61 Grose Street LEURA NSW 2780

Y Y

18/12/2006 7:12 PM




Catchment Property

B62-68 Grose Street LEURA NSW 2780

Y Y

B22 Hartley Esplanade LEURA NSW 2780

Y Y


Y Y


Y Y

B26A Hartley Esplanade LEURA NSW 2780

Y Y


Y Y


Y Y


Y Y


Y Y

B 2-6 Isabel St LEURA NSW 2780 Y Y

B230 Leura Mall LEURA NSW 2780

Y Y


Y Y


Y Y


Y Y

B236A Leura Mall LEURA NSW 2780

Y Y


Y Y


Y Y


Y Y

B244-246 Leura Mall Leura NSW 2780

N Y


Y Y

B175 Megalong Street LEURA NSW 2780

Y Y


Y Y


N Y


N Y

B5 Spencer Street LEURA NSW 2780

Y Y


Y Y


Y Y


Y Y


Y Y


Y Y


Y Y

B7 Tennyson Avenue LEURA NSW 2780

N Y


Y Y


Y Y

18/12/2006 7:12 PM


Property located in 100 Year ARI Flood Extent (Y/N?


Catchment Property

C2 Blaxland Avenue LEURA NSW 2780

Y Y


Y Y


Y Y


Y Y


Y Y


N Y


N Y


N Y

C12 Coniston Avenue LEURA NSW 2780

N Y

C80 Craigend Street LEURA NSW 2780

Y Y


Y Y


Y Y


Y Y

C81A Craigend Street LEURA NSW 2780

Y Y

C 13 Easter LEURA NSW 2780 Y Y

C4 Everglades Avenue LEURA NSW 2780

Y Y


N Y


N Y


Y Y


Y Y


Y Y


Y Y


Y Y


Y Y

CThe Everglades 37-49 Everglades Avenue LEURA NSW

Y Y

CGolf Club 23-25 Fitzroy Street LEURA NSW 2780

Y Y

C100 Gladstone Road LEURA NSW 2780

Y Y


Y Y


N Y

C103-105 Gladstone Road LEURA NSW 2

Y Y

C24 Holmes Street LEURA NSW 2780

N Y

C7 Lachlan Avenue LEURA NSW 2780

Y Y

C9 Lachlan Avenue LEURA NSW 2780

Y Y

18/12/2006 7:12 PM




Catchment Property

C2 Northcote Road LEURA NSW 2780

Y Y


Y Y


N Y

C15-17 Wentworth Avenue LEURA NSW 2780

Y Y

C5-9 Wentworth Avenue LEURA NSW 278

Y Y

C11 Wentworth Avenue LEURA NSW 278

Y Y


y y


y y

D1 Blaxland Avenue LEURA NSW 2780

N Y


Y Y


Y Y


Y Y


Y Y


Y Y


Y Y

D104-104A Gladstone Road LEURA NSW 2780

N Y

D107 Gladstone Road LEURA NSW 2780

N Y

D14-18 Jamieson St LEURA NSW 2780

N Y

D109 Gladstone Road LEURA NSW 2780

Y Y

E9-11 Cliff View Road LEURA NSW 2780

Y Y


Y Y


Y Y

E19 Cliff View Road LEURA NSW 2780

Y Y


Y Y


Y Y


Y Y

EGolf Club 23-25 Fitzroy Street LEURA NSW 2780

Y Y

E21 Sublime Point Road LEURA NSW 2780

Y Y


Y Y


Y Y


Y Y


Y Y


Y Y

18/12/2006 7:12 PM




Catchment Property


Y Y

E35-39 Sublime Point Road LEURA NSW 2780

Y Y

E41-43 Sublime Point Road LEURA NSW 2780

Y Y


Y Y


Y Y


Y Y


Y Y

F22 Gladstone Road LEURA NSW 2780

Y Y

F2-6 Herbert St LEURA NSW 2780

Y Y

F 8 Herbert St LEURA NSW 2780 Y Y

F7 Hester Place LEURA NSW 2780

N Y


Y Y


N Y

F13-15 Hester Place LEURA NSW 2780

Y Y

F31A Hester Place LEURA NSW 2780

Y Y


N Y


N Y

F41-43 Kurrawong Street LEURA NSW 2780

N Y

F45-47 Kurrawong Street LEURA NSW 2780

Y Y

F49-51 Kurrawang Street LEURA NSW 2780

Y Y

F2-10 McLauchlan Road LEURA NSW 2780

N Y

F3 Morvan Road LEURA NSW 2780

Y Y

F4 Morvan Road LEURA NSW 2780

N Y

F5-19 Morvan Road LEURA NSW 2780

Y Y

F42-44 Morven Road LEURA NSW 2780

Y Y

F51-53 Morven Road LEURA NSW 2780

Y Y

F139 Railway Parade LEURA NSW 2780

N Y


N Y


N Y

F12 Scott Avenue LEURA NSW 2780

Y Y

F 14 Scott Ave LEURA NSW 2780 Y Y



F18-20 Scott Avenue LEURA NSW 2780

Y Y

18/12/2006 7:12 PM




Catchment Property


Y Y


Y Y


N Y


Y Y


Y Y


Y Y


Y Y


Y Y


Y Y


Y Y


Y Y


Y Y


Y Y

F 77 Scott Ave Korowal School Y Y

F18-20 St Georges Road LEURA NSW 278

Y Y

F15 Vale Street LEURA NSW 2780

Y Y

F20 Vale Street LEURA NSW 2780

Y Y

18/12/2006 7:12 PM

Flood Damages Assessment - Input Parameters and Equations

D Value of Damage to Property (Internal, Structural and External)D D(0.06 + 1.42H - 0.61H 2 ) D2 Assessed value of residential property damage at 2m depth (see table below)H Depth of over floor floodingDclean Clean up cost

Internal Property Value Structural Property Value External Property Value$30,000 $10,000 $3,500

Dclean $0 - 1500 Daily Rate x Z x ln(H/0.023)Daily Rate $100 Earnings per day of one workerZ 10 Factor Accounting for sediment load and depositions

D2

18/12/2006 7:38 PM

Flood Damages - Cost Analysis

20** 50** 100 PMF 20** 50** 100 PMF 20** 50** 100 PMF37 Govett Street

LEURA NSW 2780946.56 946 945.25 J.A-3 A3-5 945.7 945.8 945.9 946.9 0.4 0.9 0.2 0.3 0.3 0.8 1190 1500 2690 1374 1500 2874 1537 1500 3037 15340 8558 2161 1500 27559

41 Govett Street KATOOMBA NSW

2780948.53 952 945.25 J.A-3 A3-5 944.9 945.0 945.1 946.2 0.5 2033 1500 3533

50 Govett Street LEURA NSW 2780

946.7 946 946 A1-5 A3-1 946.4 946.4 946.4 947.1 0.4 0.4 0.4 0.4 1.1 0.2 0.2 0.2 0.6 5198 1095 1500 7793 5631 1192 1500 8323 5308 1119 1500 7927 16223 8847 2161 1500 28731


2780948.85 947.9 947.2 A2-3A A2-3B 947.9 947.9 947.9 948.3 0.4 0.3 0.3 0.4 0.6 1600 1500 3100 1662 1500 3162 1708 1500 3208 5630 2161 1500 9291


2780956.6 954.273 952 A2-5 A2-2 952.1 952.1 952.1 952.4 0.1 0.2 487 910 1398 1094 1500 2594


2780N/A N/A 954 A2-5 A2-2 953.9 954.0 954.0 954.3 0.1 831 1500 2331

70-72 Govett Street KATOOMBA NSW

2780961.1 960.8 954 A2-5 A2-2 954.3 954.3 954.4 954.7 0.2 0.2 0.2 0.3 961 1500 2461 1012 1500 2512 1054 1500 2554 1611 1500 3111

52 Megalong Street KATOOMBA NSW

2780949.16 948 947.2 J.A-1 A1-5 947.1 947.1 947.2 947.8 0.3 1496 1500 2996


2780949.02 947.63 946.8 J.A-1 A1-5 946.9 947.0 947.0 947.6 0.1 0.1 0.1 0.4 497 946 1443 600 1264 1864 679 1455 2134 1838 1500 3338


2780949.52 947.84 946.4 A1-5 A3-1 946.6 946.6 946.7 947.2 0.1 0.1 0.1 0.4 680 1456 2136 772 1500 2272 841 1500 2341 1911 1500 3411


2780948.55 947.47 946.1 A1-5 A3-1 946.5 946.5 946.5 947.2 0.2 0.2 0.2 0.5 1082 1500 2582 1174 1500 2674 1162 1500 2662 2161 1500 3661


2780947.27 946.1 946 A1-5 A3-1 946.4 946.4 946.4 947.1 0.3 0.3 0.3 1.0 0.2 0.2 0.2 0.6 4172 1092 1500 6764 4665 1188 1500 7353 4292 1115 1500 6907 8720 2161 1500 12381


2780948.11 946.4 946 A1-5 A3-1 946.3 946.3 946.3 947.0 0.6 0.1 0.2 0.1 0.5 853 1500 2353 962 1500 2462 806 1500 2306 7216 2161 1500 10877


2780947.05 946 946 J.A-3 A3-5 945.1 945.2 945.3 946.4 0.4 0.2 5008 1054 1500 7562

66-72 Megalong Street KATOOMBA NSW

2780946.61 945.744 945.7 J.A-3 A3-5 943.8 943.8 943.9 944.9

78 Megalong Street LEURA NSW 2780

N/A 944.25 942.4 A3-5A3-

3/A4-1941.7 941.8 941.9 942.8 0.2 1157 1500 2657


943.845 941.71 939.4 A3-5A3-

3/A4-1940.0 940.1 940.1 941.0 0.3 0.3 0.4 0.8 1527 1500 3027 1662 1500 3162 1767 1500 3267 2161 1500 3661


942.985 940.552 938.2 A3-5A3-

3/A4-1938.0 938.1 938.1 939.2 0.5 2161 1500 3661


941.82 940.27 937.5 A3-5A3-

3/A4-1937.3 937.3 937.4 939.2 0.9 2161 1500 3661


940.72 938.622 936.5 A3-5A3-

3/A4-1936.4 936.5 936.5 939.2 0.6 1.4 6770 2161 1500 10431


940.81 938.104 935.3 A3-5A3-

3/A4-1935.3 935.3 935.4 939.2 1.1 2.0 8836 2161 1500 12497


940.88 939.52 934 A3-5A3-

3/A4-1934.8 934.9 934.9 939.2 0.4 0.4 0.5 2.6 1884 1500 3384 1984 1500 3484 2062 1500 3562 2161 1500 3661


940.655 939.184 933.6 A3-5A3-

3/A4-1933.9 934.0 934.0 939.2 0.2 0.2 0.2 2.8 972 1500 2472 1099 1500 2599 1201 1500 2701 2161 1500 3661

16-18 Murray Street LEURA NSW 2780 937.94 937.6 937 A6-12 Outlet 936.8 936.9 937.0 939.2 1.3 1.6 1.1 26423 7704 2161 1500 37788

39 Wilson Street KATOOMBA NSW

2780N/A N/A 954.127 A2-5 A2-2 955.0 955.0 955.0 955.3 0.4 0.4 0.4 0.6 1894 1500 3394 1928 1500 3428 1955 1500 3455 2161 1500 3661


2780N/A N/A 955.7 A2-5 A2-2 956.0 956.0 956.0 956.3 0.1 0.1 0.2 0.3 822 1500 2322 878 1500 2378 923 1500 2423 1504 1500 3004


2780N/A N/A 949.8 A1-1 A1-6 949.9 949.9 950.0 950.3 0.1 0.1 0.1 0.2 458 797 1255 540 1091 1631 616 1306 1922 1239 1500 2739


2780N/A N/A 956.5 A2-5 A2-2 956.9 956.9 956.9 957.2 0.2 0.2 0.2 0.4 1046 1500 2546 1104 1500 2604 1150 1500 2650 1708 1500 3208


2780N/A N/A 957.2 A2-5 A2-2 957.6 957.6 957.6 957.9 0.2 0.2 0.2 0.4 1081 1500 2581 1143 1500 2643 1192 1500 2692 1752 1500 3252


2780N/A N/A 959.1 A2-5 A2-2 959.7 959.8 959.8 960.1 0.3 0.3 0.3 0.5 1564 1500 3064 1630 1500 3130 1681 1500 3181 2161 1500 3661


2780961 960.7 960.2 A2-5 A2-2 960.6 960.6 960.7 961.0 0.3 0.2 0.2 0.2 0.4 1130 1500 2630 1209 1500 2709 1270 1500 2770 4293 1854 1500 7646


2780964.841 964.125 960 A2-5 A2-2 963.4 963.4 963.5 963.8 1.7 1.7 1.7 1.9 2161 1500 3661 2161 1500 3661 2161 1500 3661 2161 1500 3661

9-11 Wascoe Street LEURA NSW 2780 Varies Varies Varies A6-14 A6-15 - - - - 0.2 0.2 0.3 0.4 907 1500 2407 1119 1500 2619 1319 1500 2819 1856 1500 3356

Property at Risk of over-floor flooding Internal

Damage

Confirmed Floor Level

Height of flooding above floor level (m)20 Year Costs

D clean

Approximate Ground Level

Height of flooding above ground level level (m), for ext'l and yard damageYard Level

Flood Levels at property

D clean DD clean DStructural Damages

External Damages

PMF Flood Level

100 Year Flood Level

50 Year Flood Level

20 Yr Flood Level

Height of flooding above building ground level level (m), for structural

damages

100 Year Costs

Internal Damage

Structural Damages

External Damages

D

PMF Year Costs

Internal Damage

50 Year Costs

Structural Damages

External Damages

Internal Damage

Structural Damages

External Damages

D D clean

U/S Node

D/S Node

18/12/2006 6:48 PM


20** 50** 100 PMF 20** 50** 100 PMF 20** 50** 100 PMF7 Abbey Street LEURA NSW 2780 N/A 954.3 952.16 B1-4 B1-9 952.5 952.5 952.6 952.7 0.2 0.2 0.2 0.3 1056 1500 2556 1086 1500 2586 1113 1500 2613 1455 1500 2955

9 Abbey Street LEURA NSW 2780 N/A 954.9 951 B1-4 B1-9 951.7 951.7 951.7 951.9 0.4 0.4 0.4 0.4 1698 1500 3198 1720 1500 3220 1740 1500 3240 1980 1500 3480

11 Abbey Street LEURA NSW 2780 N/A 955.6 951 B1-4 B1-9 951.0 951.0 951.0 951.1 0.1 479 879 1358

13 Abbey Street LEURA NSW 2780 N/A 953.6 949.4 B1-9 B1-2 949.7 949.7 949.7 949.8 0.1 0.1 0.1 0.2 832 1500 2332 853 1500 2353 869 1500 2369 1064 1500 2564

15 Abbey Street LEURA NSW 2780 949.94 948.63 948.4 B1-9 B1-2 948.9 948.9 948.9 949.0 0.2 0.2 0.3 0.3 0.2 0.2 0.2 0.3 3611 1252 1500 6363 3713 1270 1500 6483 3786 1283 1500 6569 4677 1445 1500 7622

17 Abbey Street LEURA NSW 2780 N/A 951 946.9 B1-9 B1-2 947.1 947.1 947.1 947.2 0.1 0.1 0.1 0.1 661 1414 2075 681 1460 2141 696 1491 2187 877 1500 2377



23 Abbey Street LEURA NSW 2780 945.81 945.91 944.8 B1-9 B1-2 945.1 945.1 945.1 945.2 0.1 0.1 0.2 0.2 887 1500 2387 902 1500 2402 913 1500 2413 1043 1500 2543

25 Abbey Street LEURA NSW 2780 945.4 945.93 944.4 B1-2 B1-6 944.6 944.6 944.6 944.6 0.1 0.1 0.1 0.1 585 1222 1806 597 1254 1850 605 1277 1883 737 1500 2237

20 Abbey Street LEURA NSW 2780 941.48 940.5 940.5 B1-7A B1-7B 941.1 941.1 941.2 941.6 0.1 0.6 0.6 0.7 1.1 0.3 0.3 0.3 0.5 6902 1503 1500 9905 7198 1584 1500 10282 7324 1620 1500 10444 6296 8831 2161 1500 18789

22 Abbey Street LEURA NSW 2780 941.21 939.9 939.9 B1-7A B1-7B 940.7 940.7 940.7 941.2 0.8 0.8 0.8 1.3 0.4 0.4 0.4 0.6 7909 1804 1500 11213 8119 1880 1500 11498 8205 1913 1500 11619 8796 2161 1500 12458

26 Abbey Street LEURA NSW 2780 939.97 939.9 939.9 B1-7B B1-7C 940.2 940.2 940.2 940.7 0.2 0.3 0.3 0.7 0.3 0.3 0.3 0.8 0.1 0.2 0.2 0.4 9658 4011 846 1500 16016 11306 4519 951 1500 18276 12033 4743 997 1500 19274 22838 7969 1825 1500 34132

28 Abbey Street LEURA NSW 2780 941.7 941.4 939.2 B1-7B B1-7C 939.5 939.5 939.6 940.0 0.1 0.2 0.2 0.4 865 1500 2365 973 1500 2473 1023 1500 2523 1858 1500 3358

5 Craigend Street LEURA NSW 2780 956.56 955.85 955 B1-4 B1-9 955.0 955.0 955.0 955.3 0.1 854 1500 2354

7 Craigend Street LEURA NSW 2780 954.83 953.3 953.2 B1-4 B1-9 954.4 954.4 954.4 954.6 1.1 1.1 1.1 1.3 0.6 0.6 0.6 0.7 8799 2161 1500 12460 8818 2161 1500 12479 8834 2161 1500 12495 8741 2161 1500 12402

36 Craigend Street LEURA NSW 2780 945.98 943.571 943 B2-11 B2-2 943.3 943.4 943.5 943.8 0.3 0.1 0.2 0.2 0.4 874 1500 2374 1144 1500 2644 1285 1500 2785 3829 1899 1500 7228

40-42 Craigend Street LEURA NSW 2780

944.92 943.2 943 B2-11 B2-2 943.2 943.4 943.4 943.8 0.2 0.2 0.6 0.1 0.2 0.2 0.4 755 1500 2255 2618 1019 1500 5136 3411 1156 1500 6067 6607 1783 1500 9890

59 Grose Street LEURA NSW 2780 N/A 938.214 936 B1-8

B1-4/B2-3

936.2 936.2 936.2 936.9 0.1 0.1 0.1 0.4 599 1261 1860 623 1322 1944 746 1500 2246 1959 1500 3459

61 Grose Street LEURA NSW 2780 N/A 936.9 933.3 B1-8

B1-4/B2-3

932.7 932.8 932.8 933.7 0.2 1088 1500 2588

62-68 Grose Street LEURA NSW 2780 N/A 936 926 B1-8

B1-4/B2-3

926.8 926.8 926.9 928.1 0.4 0.4 0.5 1.0 1805 1500 3305 1913 1500 3413 2032 1500 3532 2161 1500 3661

18 Hartley Esplanade LEURA NSW 2780 951.51 950.733 950.1 B2-1 B2-4 950.1 950.1 950.1 950.3 0.1 664 1421 2086

22 Hartley Esplanade LEURA NSW 2780 or 169 Megalong

950.74 950.1 948.9 B2-7 B2-8 949.2 949.2 949.2 949.5 0.1 0.2 0.2 0.3 886 1500 2386 936 1500 2436 983 1500 2483 1430 1500 2930

24 Hartley Esplanade LEURA NSW 2780 949.76 949.5 948.3 B2-8 B2-9 948.8 948.8 948.8 949.0 0.2 0.3 0.3 0.3 1300 1500 2800 1322 1500 2822 1343 1500 2843 1629 1500 3129

26 Hartley Esplanade LEURA NSW 2780

950.08 948.9 947.5 B2-9 B2-10 947.7 947.8 947.9 948.2 0.1 0.1 0.2 0.3 711 1500 2211 900 1500 2400 1059 1500 2559 1668 1500 3168

26A Hartley Esplanade LEURA NSW 2780

947.76 947.6 946.4 B2-9 B2-10 946.9 946.9 946.9 947.1 0.2 0.2 0.3 0.3 1258 1500 2758 1295 1500 2795 1326 1500 2826 1669 1500 3169



32 Hartley Esplanade LEURA NSW 2780 946.92 945.31 944.7 B2-10 B2-11 945.0 945.2 945.3 945.7 0.4 0.1 0.2 0.3 0.5 799 1500 2299 1223 1500 2723 1445 1500 2945 4890 2114 1500 8504

34 Hartley Esplanade LEURA NSW 2780 946.05 945.21 944 B2-11 B2-2 944.3 944.6 944.8 945.2 0.2 0.3 0.4 0.6 1001 1500 2501 1517 1500 3017 1775 1500 3275 2161 1500 3661

2-6 Isabel St LEURA NSW 2780 N/A 937 931.4 B2-6

B1-4/B2-3

932.0 932.1 932.1 933.0 0.3 0.3 0.4 0.8 1545 1500 3045 1641 1500 3141 1738 1500 3238 2161 1500 3661

230 Leura Mall LEURA NSW 2780 N/A 957.5 954.3 B1-4 B1-9 954.3 954.3 954.3 954.5 0.1 729 1500 2229

232 Leura Mall LEURA NSW 2780 N/A 956.95 953.2 B1-4 B1-9 953.6 953.7 953.7 953.9 0.2 0.2 0.2 0.3 1201 1500 2701 1234 1500 2734 1266 1500 2766 1656 1500 3156



236A Leura Mall LEURA NSW 2780 N/A 956.2 951.4 B1-4 B1-9 951.6 951.7 951.7 951.8 0.1 0.1 0.1 0.2 771 1500 2271 800 1500 2300 824 1500 2324 1134 1500 2634

238 Leura Mall LEURA NSW 2780 N/A 956 951 B1-4 B1-9 951.1 951.1 951.1 951.2 0.1 728 1500 2228


242 Leura Mall LEURA NSW 2780 N/A 955 949.7 B1-9 B1-2 950.0 950.0 950.0 950.1 0.2 0.2 0.2 0.2 948 1500 2448 970 1500 2470 985 1500 2485 1182 1500 2682

250 Leura Mall LEURA NSW 2780 N/A 953 943.9 B1-9 B1-2 944.5 944.5 944.5 944.6 0.3 0.3 0.3 0.3 1445 1500 2945 1463 1500 2963 1475 1500 2975 1636 1500 3136


949.49 948.2 949.1 B2-7 B2-8 949.5 949.5 949.5 949.8 0.3 1.3 1.3 1.3 1.6 0.2 0.2 0.2 0.3 8801 1047 1500 11348 8756 1112 1500 11368 8703 1173 1500 11375 13113 7727 1681 1500 24020


950.57 949.23 949.2 B2-7 B2-8 949.5 949.5 949.5 949.8 0.2 0.3 0.3 0.6 0.1 0.1 0.2 0.3 3604 832 1500 5936 3954 901 1500 6355 4273 964 1500 6737 6681 1501 1500 9682

178 Megalong Street LEURA NSW 2780 952.99 949.8 949.6 B2-1 B2-4 950.1 950.1 950.1 950.3 0.3 0.3 0.3 0.5 0.2 0.2 0.3 0.3 3992 1261 1500 6752 4163 1292 1500 6955 4315 1320 1500 7135 6098 1672 1500 9270

182 Megalong Street LEURA NSW 2780 951.59 950.1 949.7 B2-1 B2-4 950.1 950.1 950.1 950.3 0.2 0.2 0.2 0.2 0.3 1057 1500 2557 1090 1500 2590 1119 1500 2619 3085 1491 1500 6076

37-39 Craigend Street LEURA NSW 2780 941.6 941.221 940 B2-5A B2-5B 940.4 940.5 940.5 941.2 0.2 0.2 0.3 0.6 1059 1500 2559 1229 1500 2729 1373 1500 2873 2161 1500 3661

5 Spencer Street LEURA NSW 2780 939.91 939.3 938 B2-5B B2-5C 938.4 938.5 938.6 939.3 0.2 0.2 0.3 0.7 1136 1500 2636 1306 1500 2806 1448 1500 2948 2161 1500 3661

7 Spencer Street LEURA NSW 2780

938.14 937.7 937.3 B2-5C B2-5D 937.3 937.4 937.5 938.2 0.1 0.5 0.1 0.5 616 1304 1920 4742 6265 2031 1500 14538

9 Spencer St LEURA NSW 2780 or 12 Tennyson Avenue

936.43 935.9 935.9 B2-5D B2-5E 936.1 936.2 936.2 937.0 0.6 0.2 0.3 0.3 1.1 0.1 0.1 0.2 0.5 3030 654 1397 5080 4019 848 1500 6367 4790 1007 1500 7298 20076 8837 2161 1500 32574

11 Spencer Street LEURA NSW 2780 937.82 936 935.3 B2-5E B2-5F 935.8 935.9 936.0 936.7 0.7 0.3 0.3 0.3 0.7 1364 1500 2864 1528 1500 3028 1661 1500 3161 7751 2161 1500 11413

15 Spencer Street LEURA NSW 2780 938.13 935.4 934 B2-5F B2-6 934.7 934.7 934.8 935.6 0.2 0.3 0.4 0.4 0.8 1610 1500 3110 1763 1500 3263 1887 1500 3387 2934 2161 1500 6596

17 Spencer Street LEURA NSW 2780 N/A 936.8 933.4 B2-5 B2-6 934.3 934.4 934.5 935.2 0.5 0.5 0.5 0.9 2026 1500 3526 2157 1500 3657 2161 1500 3661 2161 1500 3661

19 Spencer Street LEURA NSW 2780 N/A 937.4 932.7 B2-6

B1-4/B2-3

933.3 933.4 933.4 934.2 0.3 0.3 0.4 0.8 1599 1500 3099 1682 1500 3182 1770 1500 3270 2161 1500 3661

9 Tennyson Avenue LEURA NSW 2780 N/A 940 930 B2-6

B1-4/B2-3

930.8 930.9 930.9 931.9 0.4 0.4 0.5 0.9 1900 1500 3400 1995 1500 3495 2089 1500 3589 2161 1500 3661

14 Tennyson Avenue LEURA NSW 2780 N/A 936 934 B2-5 B2-6 934.5 934.5 934.6 935.2 0.2 0.3 0.3 0.6 1305 1500 2805 1381 1500 2881 1466 1500 2966 2161 1500 3661


Damage



D clean





External Damages

PMF Flood Level


50 Year Flood Level

20 Yr Flood Level


damages

100 Year Costs

Internal Damage

Structural Damages

External Damages

D

PMF Year Costs

Internal Damage

50 Year Costs

Structural Damages

External Damages

Internal Damage

Structural Damages

External Damages

D D clean

U/S Node

D/S Node

18/12/2006 6:50 PM


20 50 100 PMF 20 50 100 PMF 20 50 100 PMF2 Blaxland Avenue LEURA NSW 2780 N/A 927.84 926.5 C2-8 C2-5 926.8 926.8 926.9 927.2 0.2 0.2 0.2 0.4 928 1500 2428 990 1500 2490 1039 1500 2539 1699 1500 3199

4 Blaxland Avenue LEURA NSW 2780 N/A 929.1 927.3 C2-8 C2-5 927.7 927.7 927.7 928.1 0.2 0.2 0.2 0.4 1047 1500 2547 1107 1500 2607 1155 1500 2655 1784 1500 3284

6 Blaxland Avenue LEURA NSW 2780 N/A 930 927.8 C2-8 C2-5 928.5 928.5 928.5 928.8 0.3 0.3 0.4 0.5 1604 1500 3104 1654 1500 3154 1696 1500 3196 2161 1500 3661



12 Blaxland Avenue LEURA NSW 2780 N/A 932.5 930.8 C2-8 C2-5 930.7 930.7 930.7 931.0 0.1 790 1500 2290

14 Blaxland Avenue LEURA NSW 2780 N/A 933.6 931.7 C2-8 C2-5 931.4 931.5 931.5 931.8 0.1 484 897 1381

16 Blaxland Avenue LEURA NSW 2780 N/A 934 932 C2-8 C2-5 932.2 932.2 932.3 932.6 0.1 0.1 0.1 0.3 724 1500 2224 785 1500 2285 841 1500 2341 1464 1500 2964

76 Craigend Street LEURA NSW 2780 951.55 951.1 951.1 C1-2 C1-3 951.0 951.3 951.3 951.4 0.2 0.2 0.3 0.1 0.1 0.2 3120 671 1437 5228 3260 698 1497 5455 4688 986 1500 7174

79 Craigend Street LEURA NSW 2780 947.3 946.4 945.7 C1-4 C1-5 946.7 946.7 946.7 947.1 0.3 0.3 0.3 0.7 0.5 0.5 0.5 0.7 3821 2096 1500 7417 4114 2135 1500 7749 4340 2161 1500 8001 7376 2161 1500 11037

80 Craigend Street LEURA NSW 2780

954.17 951.96 951.3 C1-2 C1-3 952.4 952.7 952.7 952.8 0.5 0.7 0.7 0.9 0.6 0.7 0.7 0.8 6075 2161 1500 9736 7734 2161 1500 11395 7796 2161 1500 11457 8360 2161 1500 12022

81 Craigend Street LEURA NSW 2780 949.05 947.3 946.8 C1-4 C1-5 947.1 947.1 947.2 947.5 0.2 0.2 0.2 0.2 0.4 955 1500 2455 1014 1500 2514 1059 1500 2559 3750 1771 1500 7020

13 Easter LEURA NSW 2780 N/A N/A 923.4 C1-10 C1-11 923.8 923.9 924.0 924.8 0.2 0.3 0.3 0.7 1206 1500 2706 1367 1500 2867 1491 1500 2991 2161 1500 3661

4 Everglades Avenue LEURA NSW 2780

944.35 944 944 C1-4 C1-5 944.8 944.8 944.8 945.1 0.4 0.4 0.5 0.8 0.8 0.8 0.8 1.1 0.4 0.4 0.4 0.6 16267 7882 1795 1500 27445 16926 7998 1835 1500 28259 17424 8083 1866 1500 28873 23960 8859 2161 1500 36480

15 Everglades Avenue LEURA NSW 2780 N/A 938.2 936.4 C1-6 C1-7 936.0 936.1 936.1 936.5 0.1 540 1090 1630

17 Everglades Avenue LEURA NSW 2780 N/A 938.5 935.7 C1-6 C1-7 935.3 935.4 935.4 935.9 0.1 705 1500 2205


936.48 935.6 934.9 C1-6 C1-7 934.7 934.7 934.8 935.3 0.2 1146 1500 2646


937.07 933.9 933.5 C1-7 C1-8 933.6 933.6 933.7 934.3 0.4 0.1 0.1 0.4 542 1097 1639 575 1194 1769 5455 1883 1500 8838


934.57 934.5 928 C1-10 C1-11 929.6 929.7 929.7 930.4 0.8 0.8 0.9 1.2 2161 1500 3661 2161 1500 3661 2161 1500 3661 2161 1500 3661

Golf Club 23-25 Fitzroy Street LEURA NSW 2780

N/A N/A N/A C2-1 C2-2 - - - - 0.3 0.3 0.3 0.6 1319 1500 2819 1358 1500 2858 1434 1500 2934 2161 1500 3661

100 Gladstone Road LEURA NSW 2780 939.3 939.3 937.7 C2-2 C2-3 938.8 938.8 938.8 939.1 0.5 0.6 0.6 0.7 2161 1500 3661 2161 1500 3661 2161 1500 3661 2161 1500 3661

101 Gladstone Road LEURA NSW 2780 933.1 933 933 C2-7 C2-8 933.1 933.1 933.2 933.5 0.1 0.4 0.1 0.1 0.2 0.5 0.1 0.1 0.1 0.2 2141 487 909 3536 2533 560 1150 4242 4637 2821 614 1299 9370 15010 5913 1257 1500 23680

103-105 Gladstone Road LEURA NSW 2 935.72 934.4 933.74 C2-7 C2-8 934.2 934.3 934.3 934.6 0.2 0.2 0.3 0.3 0.4 1289 1500 2789 1359 1500 2859 1400 1500 2900 2882 1911 1500 6293

24 Holmes Street LEURA NSW 2780 N/A 933.9 932.9 C1-8 C1-10 931.9 932.7 932.8 933.0 0.1 474 861 1335

7 Lachlan Avenue LEURA NSW 2780

964.1 962.8 961.4 C1-2 C1-3 962.7 962.8 962.8 962.9 0.1 0.7 0.7 0.7 0.7 2161 1500 3661 2161 1500 3661 2161 1500 3661 1835 2161 1500 5497

9 Lachlan Avenue LEURA NSW 2780

960.6 960 958.15 C1-2 C1-3 959.4 959.5 959.5 959.6 0.6 0.7 0.7 0.7 2161 1500 3661 2161 1500 3661 2161 1500 3661 2161 1500 3661

2 Northcote Road LEURA NSW 2780 942.53 941.6 940.3 C1-4 C1-5 940.8 940.8 940.9 941.1 0.3 0.3 0.3 0.4 1371 1500 2871 1406 1500 2906 1432 1500 2932 1851 1500 3351

3 Northcote Road LEURA NSW 2780 939.65 939.7 938.3 C1-5 C1-6 938.2 938.2 938.2 938.5 0.1 668 1431 2099

4 Northcote Road LEURA NSW 2780 N/A 945.6 943.6 C1-4 C1-5 944.4 944.4 944.5 944.8 0.4 0.4 0.4 0.6 1887 1500 3387 1923 1500 3423 1950 1500 3450 2161 1500 3661

15-17 Wentworth Avenue LEURA NSW 2780

N/A 937.5 931.8 C2-8 C2-5 932.1 932.1 932.1 932.4 0.1 0.1 0.2 0.3 844 1500 2344 903 1500 2403 958 1500 2458 1565 1500 3065

U/S Node

D/S Node

PMF Year Costs

Internal Damage

50 Year Costs

Structural Damages

External Damages

Internal Damage

Structural Damages

External Damages

D D clean


damages

100 Year Costs

Internal Damage

Structural Damages

External Damages

DPMF Flood

Level100 Year

Flood 50 Year Flood

20 Yr Flood


External Damages


Damage



D clean


Height of flooding above ground level level (m), for ext'l and yard damage

Yard Level


18/12/2006 6:50 PM


20** 50** 100 PMF 20** 50** 100 PMF 20** 50** 100 PMF5 Blaxland Avenue LEURA NSW 2780

N/A 931.8 925.8 D-5 D-3 926.1 926.1 926.1 926.6 0.1 0.2 0.2 0.4 835 1500 2335 920 1500 2420 989 1500 2489 1856 1500 3356

7 Blaxland Avenue LEURA NSW 2780

N/A 930.6 926.9 D-5 D-3 927.3 927.3 927.4 927.8 0.2 0.2 0.2 0.4 1132 1500 2632 1204 1500 2704 1264 1500 2764 2014 1500 3514


N/A 932 930.9 D-5 D-3 931.1 931.1 931.1 931.5 0.1 0.1 0.1 0.3 572 1185 1757 649 1385 2034 712 1500 2212 1527 1500 3027


932.7 932.4 930.8 D-5 D-3 931.1 931.1 931.1 931.5 0.1 0.2 0.2 0.4 856 1500 2356 923 1500 2423 977 1500 2477 1688 1500 3188


933.8 933.5 932 D-5 D-3 932.3 932.3 932.4 932.7 0.2 0.2 0.2 0.4 946 1500 2446 1005 1500 2505 1053 1500 2553 1688 1500 3188

109 Gladstone Road LEURA

936.615 936.58 936.53 D-4 D-5 936.2 936.3 936.3 936.8 0.16 0.20 0.1 8216 3159 791 1500 13666


Damage


Height of flooding above floor level (m)

20 Year Costs

D clean





External Damages

PMF Flood Level


50 Year Flood Level

20 Yr Flood Level


damages

100 Year Costs

Internal Damage

Structural Damages

External Damages

D

PMF Year Costs

Internal Damage

50 Year Costs

Structural Damages

External Damages

Internal Damage

Structural Damages

External Damages

D D cleanU/S Node D/S Node

18/12/2006 6:51 PM


20** 50** 100 PMF 20** 50** 100 PMF 20** 50** 100 PMF21 Sublime Point RoadLEURA NSW 2780 938.96 938 935.6 E1-1 E1-8 937.2 937.3 937.3 938.0 0.0 0.8 0.8 0.9 1.2 2161 1500 3661 2161 1500 3661 2161 1500 3661 1205 2161 1500 4866

23 Sublime Point RoadLEURA NSW 2780 936.51 936.2 935.4 E1-8 E1-8A 935.5 935.5 935.6 935.7 0.1 0.1 0.1 0.2 478 874 1352 514 1006 1520 687 1473 2160 985 1500 2485

25 Sublime Point RoadLEURA NSW 2780 936.43 935.6 935.1 E1-8A E1-9 935.0 935.0 935.0 935.2 0.1 492 927 1419

27 Sublime Point RoadLEURA NSW 2780 933.75 933.3 933 E1-9 E1-9A 933.2 933.2 933.2 933.5 0.2 0.1 0.1 0.1 0.2 583 1217 1800 668 1430 2099 731 1500 2231 2887 1268 1500 5655

29 Sublime Point RoadLEURA NSW 2780 934.015 934.3 932.2 E1-9A E1-10 932.3 932.3 932.3 932.6 0.2 1047 1500 2547

31 Sublime Point RoadLEURA NSW 2780 931.41 931.2 931.2 E1-10 E1-10A 931.7 931.7 931.7 932.0 0.3 0.3 0.3 0.6 0.5 0.5 0.5 0.8 0.3 0.3 0.3 0.4 12615 6175 1319 1500 21609 13247 6335 1358 1500 22440 13865 6489 1396 1500 23251 20564 8056 1856 1500 31976

33 Sublime Point RoadLEURA NSW 2780 933.37 932.1 930.2 E1-10A E1-10B 930.4 930.4 930.5 930.8 0.1 0.1 0.1 0.3 742 1500 2242 796 1500 2296 826 1500 2326 1468 1500 2968

35-39 Sublime Point RoadLEURA NSW 2780 931.8 931.4 928.13 E1-10C E1-11 928.4 928.4 928.4 928.8 0.1 0.1 0.1 0.3 809 1500 2309 868 1500 2368 904 1500 2404 1591 1500 3091

41-43 Sublime Point RoadLEURA NSW 2780 921.25 921.1 921.1 E1-13C E1-14 921.3 921.3 921.4 921.9 0.1 0.1 0.1 0.7 0.2 0.2 0.3 0.8 0.1 0.1 0.1 0.4 4624 3409 727 1500 10261 5735 3728 790 1500 11753 7036 4100 864 1500 13500 22216 8163 1897 1500 33776

45 Sublime Point RoadLEURA NSW 2780 922.81 922.76 920.3 E1-14 E1-16 920.5 920.5 920.6 921.1 0.1 0.1 0.1 0.4 656 1403 2059 765 1500 2265 859 1500 2359 1864 1500 3364

49 Sublime Point RoadLEURA NSW 2780 N/A 922.71 917.5 E1-14 E1-16 918.6 918.7 918.7 919.1 0.6 0.6 0.6 0.8 2161 1500 3661 2161 1500 3661 2161 1500 3661 2161 1500 3661

U/S Node D/S NodeProperty at Risk of over-floor flooding Internal

Damage

ConfirmedFloorLevel

Height of flooding above floor level(m)

20 Year Costs

D cleanApproximateGround Level

Height of flooding above ground levellevel (m), for ext'l and yard damageYard Level


D clean DD clean D StructuralDamages

ExternalDamages

PMF FloodLevel

100 YearFlood Level

50 Year FloodLevel

20 Yr FloodLevel

Height of flooding above buildingground level level (m), for structural

100 Year CostsInternalDamage

StructuralDamages

ExternalDamagesD

PMF Year CostsInternalDamage

50 Year CostsStructuralDamages

ExternalDamages

InternalDamage

StructuralDamages

ExternalDamagesD D clean

30/04/2008 3:38 PM


20** 50** 100 PMF 20** 50** 100 PMF 20** 50** 100 PMF22 Gladstone Rd LEURA NSW 2780

936.98 935.054 933.6 F1-5 F1-2 933.5 933.6 933.6 933.8 0.1 574 1192 1766

8 Herbert St LEURA NSW 2780

N/A 910 904.7 F1-3 F1-11 905.7 905.8 905.8 906.4 0.5 0.5 0.6 0.9 2161 1500 3661 2161 1500 3661 2161 1500 3661 2161 1500 3661

13-15 Hester Place LEURA NSW 2780

895.865 892.983 891.95 F2-1 F1-4/F2-2 892.3 892.4 892.5 893.2 0.2 0.2 0.2 0.3 0.6 1073 1500 2573 1178 1500 2678 1324 1500 2824 3353 2161 1500 7014

9 Hester Place LEURA NSW 2780

889.5 887.481 887.1 F2-1 F1-4/F2-2 888.0 888.1 888.2 889.0 0.5 0.6 0.7 1.6 0.5 0.5 0.5 1.0 6411 2030 1500 9941 6812 2111 1500 10423 7429 2161 1500 11090 7865 2161 1500 11526


894.87 891.54 889.5 F2-1 F1-4/F2-2 888.9 889.0 889.1 889.9 0.2 1185 1500 2685


N/A 885.69 883.75 F2-1 F1-4/F2-2 883.7 883.7 883.9 884.9 0.1 0.6 474 861 1336 2161 1500 3661

3 Morvan Road LEURA NSW 2780

N/A 935.85 935.1 F1-12 F1-1 935.6 935.6 935.6 936.1 0.2 0.3 0.3 0.5 1310 1500 2810 1325 1500 2825 1344 1500 2844 2089 1500 3589

4 Morvan Road LEURA NSW 2780

934.85 934.84 933.4 F1-5 F1-2 933.5 933.6 933.6 933.8 0.1 0.1 0.1 0.2 561 1155 1716 582 1215 1797 603 1270 1873 1017 1500 2517

5-19 Morvan Road LEURA NSW 2780

N/A 936.2 935 F1-12 F1-1 935.6 935.6 935.6 936.1 0.3 0.3 0.3 0.5 1500 1500 3000 1515 1500 3015 1532 1500 3032 2161 1500 3661

12 Scott Avenue LEURA NSW 2780

930.2 929.9 929.85 F1-14 F1-15 929.9 930.0 930.0 930.2 0.1 0.1 0.3 0.1 0.1 0.2 1563 500 958 3022 1747 533 1068 3347 3977 948 1500 6425

14 Scott Ave LEURA NSW 2780

929.5 927.5 927.4 F1-15 F1-6 927.4 927.5 927.5 927.9 0.4 0.1 0.3 521 1027 1548 5331 1325 1500 8155


932.95 932.9 932.8 F1-2 F1-13 932.9 932.9 932.9 933.1 0.1 0.2 0.1 0.1 464 822 1286 7700 3171 903 1500 13275


928.7 928.6 928.7 F1-15 F1-6 928.8 928.8 928.9 929.1 0.1 0.1 0.2 0.4 0.2 0.2 0.3 0.5 0.1 0.1 0.1 0.2 6032 3243 463 816 10553 7313 3629 542 1095 12579 8081 3860 590 1235 13766 15315 6002 1075 1500 23892

18-20 Scott Avenue LEURA NSW 2780

928.97 928.5 927.6 F1-15 F1-6 927.8 927.9 927.9 928.3 0.1 0.1 0.2 0.3 760 1500 2260 896 1500 2396 998 1500 2498 1633 1500 3133


932.32 932.1 932 F1-2 F1-13 932.6 932.6 932.6 932.8 0.2 0.2 0.3 0.4 0.5 0.5 0.5 0.7 0.3 0.3 0.3 0.4 10852 5811 1428 1500 19591 11238 5909 1449 1500 20096 11580 5996 1468 1500 20544 16806 7269 1778 1500 27353


926.22 926.20 925.6 F1-6 F1-7 925.8 925.9 926.0 926.4 0.2 0.2 0.1 0.1 0.2 0.4 655 1401 2056 855 1500 2355 1033 1500 2533 10533 3737 1932 1500 17703


926.28 925.20 924.6 F1-6 F1-7 925.2 925.2 925.3 925.8 0.1 0.6 0.3 0.3 0.4 0.6 1441 1500 2941 1595 1500 3095 2368 1743 1500 5611 7207 2161 1500 10868


925.85 924.69 923.9 F1-6 F1-7 924.3 924.4 924.4 925.0 0.3 0.2 0.2 0.3 0.5 1073 1500 2573 1226 1500 2726 1398 1500 2898 4274 2161 1500 7935


925.20 924.57 923.4 F1-6 F1-7 923.8 923.9 923.9 924.5 0.2 0.2 0.3 0.6 1096 1500 2596 1240 1500 2740 1413 1500 2913 2161 1500 3661


924.46 923.79 922.6 F1-7 F1-8 923.0 923.1 923.2 923.8 0.2 0.3 0.3 0.6 1200 1500 2700 1325 1500 2825 1499 1500 2999 2161 1500 3661


923.17 922.80 921.9 F1-7 F1-8 922.0 922.1 922.2 922.8 0.1 0.1 0.1 0.4 520 1026 1546 657 1405 2062 839 1500 2339 1955 1500 3455

34-36 Scott Avenue LEURA NSW 2780

922.48 921.77 921 F1-7 F1-8 920.8 920.8 920.9 921.5 0.3 1343 1500 2843


921.48 920.99 920.1 F1-7 F1-8 919.5 919.6 919.6 920.2 0.1 558 1145 1703


919.6 919.25 918.7 F1-7 F1-8 918.5 918.5 918.6 919.2 0.2 1274 1500 2774

77 Scott Ave Korowal School

N/A 903.5 892.7 F1-3 F1-11 894.0 894.1 894.2 894.9 0.7 0.7 0.7 1.1 2161 1500 3661 2161 1500 3661 2161 1500 3661 2161 1500 3661

U/S Node D/S NodePMF Year Costs

Internal Damage

50 Year Costs

Structural Damages

External Damages

Internal Damage

Structural Damages

External Damages

D D clean


damages

100 Year Costs

Internal Damage

Structural Damages

External Damages

DPMF Flood

Level100 Year

Flood Level50 Year Flood

Level20 Yr Flood

LevelD clean DD clean D

Structural Damages

External Damages


Damage


Height of flooding above floor level (m)

20 Year Costs

D clean




18/12/2006 6:52 PM

COST BENEFIT ANALYSIS

Catchment A Summary

Existing AAD 7% interest rate, 40 yrs Option Revised AAD 7% interest rate, 40 yrs Cost Savings Benefit/Cost$11,520 $172,506 1 $10,102 $151,272 $98,000 $21,234 0.22$11,520 $172,506 2 $11,029 $165,153 $58,000 $7,352 0.13$11,520 $172,506 7 $11,296 $169,151 $24,000 $3,354 0.14$11,520 $172,506 8 $10,396 $155,674 $24,000 $16,831 0.70$11,520 $172,506 9 $10,102 $151,272 $81,000 $21,234 0.26

Catchment B Summary

Existing AAD 7% interest rate, 40 yrs Option Revised AAD 7% interest rate, 40 yrs Cost Savings Benefit/Cost$31,918 $477,955 12,13 $29,362 $439,680 $234,000 $38,275 0.16$31,918 $477,955 14 $31,399 $470,183 $24,000 $7,772 0.32$31,918 $477,955 17 $29,268 $438,272 $254,000 $39,682 0.16$31,918 $477,955 20,21 $28,925 $433,136 $462,000 $44,819 0.10

Catchment C Summary

Existing AAD 7% interest rate, 40 yrs Option Revised AAD 7% interest rate, 40 yrs Cost Savings Benefit/Cost$17,574 $263,161 29 $13,506 $202,245 $33,000 $60,916 1.85$17,574 $263,161 34 $16,840 $252,170 $56,000 $10,991 0.20$17,574 $263,161 36 $16,906 $253,158 $124,000 $10,003 0.08$17,574 $263,161 37 $14,820 $221,921 $42,000 $41,240 0.98

Catchment D Summary

Existing AAD 7% interest rate, 40 yrs Option Revised AAD 7% interest rate, 40 yrs Cost Savings Benefit/Cost$2,065 $30,922 39 $2,062 $30,877 $43,000 $45 0.0010

Catchment E Summary

Existing AAD 7% interest rate, 40 yrs Option Revised AAD 7% interest rate, 40 yrs Cost Savings Benefit/Cost$8,878 $132,943 55 $8,464 $126,744 $190,000 $6,199 0.03$8,878 $132,943 57 $7,312 $109,493 $205,000 $23,450 0.11$8,878 $132,943 59 $8,540 $127,882 $76,000 $5,061 0.07$8,878 $132,943 60 $5,295 $79,290 $400,000 $53,653 0.13

Catchment F Summary

Existing AAD 7% interest rate, 40 yrs Option Revised AAD 7% interest rate, 40 yrs Cost Savings Benefit/Cost$13,774 $206,258 43 $8,456 $126,627 $258,000 $79,631 0.31$13,774 $206,258 47 $11,545 $172,882 $32,000 $33,376 1.04

29/04/2008 3:23 PM

Appendix G Draft Local Flood Policy

South Leura Floodplain Risk Management Study & Plan - 29 April 2008 Page G

k:\20018804.00 south leura flood study, floodplain mgt study and plan\eng-plan\reports\appg\draft local floodplain risk management policy.doc

Draft Local Floodplain Risk ManagementPolicy

1.0 IntroductionThis Draft Local Floodplain Risk Management Policy has been prepared in line with therequirements of the Floodplain Development Manual (NSW Government, April 2005), including theNSW Government’s Flood Prone Land Policy. It applies to the area assessed as part of the SouthLeura Flood Study, Floodplain Management Study and Plan, which includes sections of the LeuraFalls Creek, Gordon Creek and Valley of the Waters Creek catchments.

It is expected that this Draft Local Floodplain Risk Management Policy will be incorporated byCouncil into the Blue Mountains Better Living Development Control Plan..

1.1.1 Aims and Objectives

The primary objectives of this policy are as follows:• To exercise Council’s duty of care, in order that the development of properties

subjected to flooding within South Leura is undertaken in a reasonable andresponsible manner to minimise the potential risks associated with a major floodevent;

• Inform the community about the extent and degree of hazard of flood prone land inthe area and the Councils policy in relation to the development and use of floodprone land;

• Define the Flood Planning Levels (FPLs) to be used for floodplain developmentand planning purposes;

• Reduce the flood risk and damage to existing areas of development;• Ensure that future land use and development is compatible with flood risk; and• To ensure that buildings and services required for evacuation and emergency

needs are sited above the FPL.

2.0 Controls

2.1 All Development• All structures below the Flood Planning Level shall be constructed from flood

compatible materials.• All development must be designed and constructed so that it will have a low risk of

instability due to flood hazard.• All development must be designed and constructed so that it will not impact on

surrounding properties.• All foundation structures, where the floor level is greater than 500mm above the

existing ground level, are to incorporate a suspended floor on open pier/pilefootings to allow for the flow of surface water and flood storage.

• All electrical equipment, wiring, fuel lines or any other service pipes andconnections shall be waterproofed to the Flood Planning Level (FPL)

• For existing structures, tolerance of up to minus 100mm may be applied to theFlood Planning Level in respect of the determination of the criteria for


compliance with these controls. The floor level of all new structures must be to theFlood Planning Level as set out in the controls.

2.1.1 Filling of Land or Enclosure of Structures

The filling of land or enclosure of structures will only be permitted where there is no net decrease infloodplain storage capacity for the property and there is no increase in flood impacts to surroundingproperties.

2.2 Residential2.2.1 New Dwellings, Replacement Dwellings and Additions

For residential developments, all floor levels shall be at or above the Flood Planning Level orraised to the Flood Planning Level.

An addition to a single residential dwelling may be permissible where existing floor levels areretained below the Flood Planning Level provided that the following controls are complied with:

• The property must not be subject to a High Hazard Classification.• The floor levels of the addition must be at or above the Flood Planning Level.• If the floor level of the existing dwelling is to be retained at the existing level, the

existing dwelling must be satisfactorily flood proofed (either wet or dry) to theFlood Planning Level. This is considered to be a temporary measure pendingfuture raising of the floor levels to the Flood Planning Level.

• The addition must be designed and constructed such that it does not preclude theraising of the floor level of the existing structure to the Flood Planning Level at afuture date or when further additions are proposed, eg through the provision of aconstruction joint.

• A second storey addition to the dwelling requires the floor level of the secondstorey to be of a height that allows for the internal ground floor of the existingdwelling to be either at or raised to the Flood Planning Level whilst maintainingCouncil's minimum floor to ceiling height requirements of 2.4m.

2.2.2 Carparking Facilities

The floor level of new enclosed garages shall be at or above the Flood Planning Level.Consideration may be given to a floor level at a lower level where it can be demonstrated thatproviding the floor level at the Flood Planning Level is not practical.

Basement (ie below natural ground level) carparking must have all access and potential water entrypoints above the Flood Planning Level.

Open carpark areas and carports are permissible at the existing ground level.

2.2.3 Development on Land with a High Hazard Classification

For residential development on land that has a High Hazard Classification, there is to be no netloss in flood storage and floodway area, as a result of the development, for the Probable MaximumFlood event, ie the development is not to increase its impact on the floodway. All structures are tobe designed to withstand the High Hazard condition.

Open carpark areas and carports on land that has a High Hazard Classification are notpermissible in a floodway area.


2.3 Industrial and Commercial2.3.1 New Developments and Additions to Existing Development

All floor levels of the development, including any existing components to be retained, are to be at orabove the Flood Planning Level or raised to the Flood Planning Level.

2.3.2 The Following Exceptions may apply for Commercial/Industrial Development

Where constructing the floor level at the Flood Planning Level or raising the floor level of existingdevelopment to the Flood Planning Level may be difficult to achieve due to site and accessconstraints (eg within a shopping precinct), consideration may be given to a floor level with afreeboard of less than 500mm above the 1 in 100 year ARI storm event level provided thatsatisfactory flood proofing (either wet or dry) is achievable to the Flood Planning Level.

2.3.3 Shop Top Housing

The floor levels of the residential component of Shop Top Housing are to be at or above theProbable Maximum Flood Level or Flood Planning Level (whichever is the higher level).

2.3.4 Change of Use of Existing Premises

All floor levels of the development, including any existing components to be retained, are to be at orabove the Flood Planning Level or raised to the Flood Planning Level.

2.3.5 The Following Exceptions may apply for Change of Use of Existing Premises

Where constructing the floor level at the Flood Planning Level or raising the floor level of existingdevelopment to the Flood Planning Level may be difficult to achieve due to site and accessconstraints, consideration may be given to satisfactory flood proofing (either wet or dry) to the FloodPlanning Level.

2.3.6 Carparking Facilities

Basement (ie below natural ground level) or enclosed carparking facilities must have all access,ventilation and any other potential water entry point above the Probable Maximum Flood level orFlood Planning Level (whichever is the higher) and a clearly signposted flood free pedestrianevacuation route from the basement area separate to the vehicular access ramps.

Open carpark areas and carports are permissible at the existing ground level.

2.3.7 Development on Land with High Hazard Classification

For commercial and industrial development on land that has a High Hazard Classification, there isto be no net loss in flood storage and floodway area, as a result of the development, for the 1 in 100year ARI flood event, ie the development is not to increase its impact in the floodway. All structuresare to be designed to withstand the High Hazard condition. Open carpark areas and carports onland that has a High Hazard Classification are not permissible in a floodway area.


3.0 Provision of Flood Information

3.1 Section 149 CertificatesA 149 Certificate is a planning certificate under Section 149 of the Environmental Planning andAssessment Act 1979 and is issued to future residents. Planning certificates give information on thedevelopment potential of a parcel of land including information on whether the land is affected byflooding. It is recommended that the following information be provided on Section 149(2) Certificateswhere appropriate:

• For properties within the FPL (High Hazard)

Based on information available to Council, the subject property is below Council’s Flood PlanningLevel and therefore subject to Council’s Flood Development Control Plan. The property is alsoidentified as being within the High Hazard – Floodway category during a 1 in 100 year ARI stormevent. Information relating to the flood risk should be obtained from Council

• For properties within the FPL (Low Hazard)

Based on the information available to Council the subject property is below Council’s FloodPlanning Level and therefore subject to Council’s Floodplain Development Control Plan. Theproperty is also identified as being within the Low Hazard – Floodway category during a 1 in 100year ARI storm event. Information relating to the flood risk should be obtained from Council.

4.0 Lodgement Information

4.1 Pre-lodgement InformationThe Council can be contacted to ascertain the FPL. Properties encompassed or intersected by theFPL will need to provide, as a minimum the information described in the following section.

4.2 Information to be submitted with theDevelopment Application

4.2.1 Flood Planning Levels – Hazard Classification

A statement of the Flood Planning Level and Hazard Classification details that apply to the subjectproperty are to be submitted with the application.

4.2.2 Survey Details

In addition to the requirement to lodge survey details with the Development Application, the SurveyPlan prepared by a Registered Surveyor must also indicate the following:

• The location of existing buildings or structures;• The floor levels and ceiling heights of all existing buildings or structures to be

retained;• Existing and/or proposed drainage easements and watercourses, or other means

of conveying stormwater that are relevant to the flood characteristics of the site


• Flood Planning Level and flood extents• 0.2 metre contour intervals across the entire property; and• All levels must be relative to Australian Height Datum (AHD)

5.0 Glossary

5.1 DefinitionsNote: For expanded list of definitions, refer to Glossary contained within the NSW GovernmentFloodplain Development Manual – April 2005 edition.

TERM DEFINITIONAnnual ExceedanceProbability (AEP)

The chance of a flood of a given or larger size occurring in any oneyear, usually expressed as a percentage. The 1% AEP means thatthere is a 1% change (that is, one-in-100 chance) of thecorresponding flood discharge or larger occurring in any one year.In relation to the economic life of structures, there is a 26% chanceof the 1% AEP event occurring in a 30 year period, a 48% changeof occurrence in a 50 year period and a 99.9% chance within a 100year period.

Australian Height Datum(AHD)

A common national surface level datum correspondingapproximately to mean sea level

Flood Affected Properties Properties that are either encompassed or intersected by the FloodPlanning Level (FPL).

Flood Planning Level (FPL) Flood levels selected for planning purposes, as determined inFlood Risk Management Studies and incorporated in Flood RiskManagement Plans. For South Leura, it is the flood levels derivedfrom the 1% AEP flood event, plus the addition of a 500mmFreeboard

Flood Prone/Liable Land Land susceptible to flooding up to Probable Maximum Flood (PMF)event

Flood Proofing – DRY Protecting a building by sealing its exterior walls to prevent theentry of flood waters (Source: Homeowner’s Guide to Retrofitting –Six Ways to Protect Your House from Flooding – USA – FederalEmergency Management Agency, June 1998)

Flood Proofing – WET A combination of measures incorporated in the design,construction and alteration of individual buildings, structures andsurrounds, to be able to withstand the forces due to ingress andpassage of flood waters to mitigate flood damages and remainstructurally sound

Floodway Those areas of the floodplain where a significant discharge orwater occurs during floods, they are often aligned with naturallydefined channels. Floodways are areas that, even if only partiallyblocked, would cause a significant redistribution of flood flow, or asignificant increase in flood levels.

Freeboard The factor of safety usually expressed as a height above thedesignated flood. Freeboard tends to compensate for factors suchas wave action localised hydraulic effects, ‘greenhouse’ andclimatic change, as well as sensitivity of flood modelling data. Thedefault value for freeboard is 500mm unless a site-specificfreeboard to take account of localised effects is required.

High Hazard Where land may be affected by floodway or flood storage subjectto a combination of flood water velocities greater than 2.0 metres


per second and/or flood water depths greater than 0.8 metres indepth. Damage to structures is possible and wading would beunsafe for able-bodied adults.

Local OverlandFlooding

Inundation by local run-off rather than overbank discharge from acreek, estuary or lake.

Low Hazard Where land may be affected by floodway or flood storage subjectto a combination of flood water velocities less than 2.0 metres persecond and flood water depths less than 0.8 metres. Nuisancedamage to structures is possible and able-bodied adults wouldhave little difficulty wading.

Major Drainage Major drainage involves:• The floodplains or original watercourses (which may now be

piped, channelised or diverted), or sloping areas whereoverland flows develop along alternative paths once systemcapacity is exceeded; and/or

• Water depths generally in excess of 300mm (in the majorsystem design storm as defined in the current version ofAustralian Rainfall and Runoff). These conditions may resultin danger to personal safety and property damage to bothpremises and vehicles; and/or

• Major overland flowpaths through developed areas outside ofdefined drainage reserves; and/or

• The potential to affect a number of buildings along the majorflow path.

Probable MaximumFlood (PMF)

The largest flood that could conceivably occur at a particularlocation, usually estimated from probable maximum precipitation.

k:\20018804.00 south leura flood study, floodplain mgt study and plan\eng-plan\reports\app g\draft local floodplain risk management policy.doc

5.2 Flood Compatible Materials

Building Component Flood Compatible Material BuildingComponent Flood Compatible Material

Flooring and SubFloor Structure

• pier and beam construction or• suspended reinforced concrete slab

Doors • solid panel with waterproof adhesives• flush door with marine ply filled with closed cell

foam• painted material construction• aluminium or galvanized steel frame

Floor Covering • clay tiles• concrete, precise or in situ• concrete tiles• epoxy, formed-in-place• mastic flooring, formed in place• rubber sheets or tiles with chemical-set adhesive• silicone floors formed-in-place• vinyl sheets or tiles with chemical-set adhesive• ceramic tiles, fixed with mortar or chemical set

adhesive• asphalt tiles, fixed with mortar or chemical-set

adhesive• removable rubber-backed carpet

Wall and CeilingLinings

• brick, face or glazed• clay tile glazed in waterproof mortar• concrete• concrete block• steel with waterproof applications• stone, natural solid or veneer, waterproof grout• glass blocks• glass• plastic sheeting or wall with waterproof

adhesive

Wall Structure • solid brickwork, blockwork, reinforced, concreteor mass concrete

Insulation • foam or closed cell types

Windows Aluminium frame with stainless steel or brass rollers Nails, Bolts,Hinges and Fitting

• galvanised• removable pin hinges

Appendix H Mitigation Options

South Leura Floodplain Risk Management Study & Plan - 29 April 2008 Page H

South Leura Flood Study - Floodplain Management Study and Plan Job Number: 20018804.00Strategic Cost Estimate

File Location: K:\20018804.00 South Leura Flood Study, Floodplain Mgt Study and Plan\Eng-Plan\Analysis\Strategic Cost Estimate\[Strategic Cost Estimate_Catch A Rev C.xls]A1-2 to A3-1Section A1-1 to A1-6

Item Unit Quantity Rate $ Base Total $ Contingency (%) EstimateIncluding

Contingency

Comment / Reference RawlinsonsReference

1 INVESTIGATION AND DESIGN1a Investigation and Design

Detailed design and documentation item 1 5,000 5,000 30 6,500 Provisional AllowanceOther agency costs item 1 5,000 5,000 50 7,500 Provisional Allowance

2 INFRASTRUCTURE CONSTRUCTION2a Demolition Works

Clear existing Landscape and stockpile m2 0 7 - 30 - Assumed 150 thk topsoil removal P205Demolish and dispose of existing road pavement wearing coarse m2 81 3 243 30 316 Assume 80 thk AC wearing coarse P206Remove and dispose of existing pipe m 27 72 1,944 30 2,527 Nominal trench and pipe excavation assumed P206 + P205

2b Stormwater Drainage UpgradeInstall new stormwater drainage pipe including trench backfill m 54 598 32,265 30 41,945 Dia 1050 pipe P207 + P647Install new concrete headwalls item 1 3,500 3,500 30 4,550 Allow for twin 1050 dia pipe P648Install new concrete inlet pit item 1 5,000 5,000 30 6,500 Allow for twin 1050 dia pipe P468Construct new channel widening m2 0 20 - 30 - Channel construction assumed to be 150mm thick rock pitched, 8m wide total P646

2c ReinstatementReinstate existing road pavement m2 81 70 5,670 30 7,371 Assumed 50thk AC wearing coarse on 450thk DGB base P646Reinstate existing landscaping m2 0 5 - 30 - Assumed reinstatement of existing P220

3 Ancillary Works3a Environmental Works

Water quality and Monitoring item 1 2,000 2,000 50 3,000 Provisional AllowanceOther agency costs item 1 1,000 1,000 50 1,500 Provisional Allowance

3b General ActivitiesSite establishment and overheads item 1 5,000 5,000 30 6,500 Provisional AllowanceTemporary traffic management item 1 5,000 5,000 30 6,500 Provisional Allowance

GRAND TOTAL 71,622 94,709

Assumptions:The following assumptions have been made in undertaking the Strategic Cost Estimate for above infrastructure works

1 Unit rates for the infrastructure costs have been taken from Rawlins Edition 23, 2005.2 Cost estimate does not include any cost for utility adjustments3 Estimates are for concept planning purposes only and do not represent a detailed bill of quantities

Data:Pipe Dia 1.05No. of pipes 2Pipe Length 27Trench Width 3Channel Length




Contingency





Clear existing Landscape and stockpile m2 0 7 - 30 - Assumed 150 thk topsoil removal P205Demolish and dispose of existing road pavement wearing coarse m2 24 3 72 30 94 Assume 80 thk AC wearing coarse P206Remove and dispose of existing pipe m 10 72 720 30 936 Nominal trench and pipe excavation assumed P206 + P205

2b Stormwater Drainage UpgradeInstall new stormwater drainage pipe including trench backfill m 20 458 9,150 30 11,895 Dia 750 pipe P207 + P647Install new concrete headwalls item 2 3,500 7,000 30 9,100 Allow for twin 750 dia pipe P648Install new concrete inlet pit item 0 5,000 - 30 - Allow for twin 750 dia pipe P468Construct new channel widening m2 0 20 - 30 - Channel construction assumed to be 150mm thick rock pitched, 8m wide total P646



Water quality and monitoring item 1 2,000 2,000 50 3,000 Provisional AllowanceEnvironmental monitoring item 1 1,000 1,000 50 1,500 Provisional Allowance





Data:Pipe Dia 0.75No. of pipes 2Pipe Length 10Trench Width 2.4Channel Length




Contingency





Clear existing Landscape and stockpile m2 0 7 - 30 - Assumed 150 thk topsoil removal P205Demolish and dispose of existing road pavement wearing coarse m2 24.3 3 73 30 95 Assume 80 thk AC wearing coarse P206Remove and dispose of existing pipe m 9 72 648 30 842 Nominal trench and pipe excavation assumed P206 + P205


2c ReinstatementReinstate existing road pavement m2 24.3 70 1,701 30 2,211 Assumed 50thk AC wearing coarse on 450thk DGB base P646Reinstate existing landscaping m2 0 5 - 30 - Assumed reinstatement of existing P220


Water quality and monitoring item 1 2,000 2,000 50 3,000 Provisional AllowanceOther agency costs item 1 1,000 1,000 50 1,500 Provisional Allowance







File Location: K:\20018804.00 South Leura Flood Study, Floodplain Mgt Study and Plan\Eng-Plan\Analysis\Strategic Cost Estimate\[Strategic Cost Estimate_Catch A Rev C.xls]A1-2 to A3-1Section A1-2 to JA-1


Contingency





Clear existing Landscape and stockpile m2 0 7 - 30 - Assumed 150 thk topsoil removal P205Demolish and dispose of existing road pavement wearing coarse m2 29.325 3 88 30 114 Assume 80 thk AC wearing coarse P206Remove and dispose of existing pipe m 11.5 72 828 30 1,076 Nominal trench and pipe excavation assumed P206 + P205









Data:Pipe Dia 0.825No. of pipes 2Pipe Length 11.5Trench Width 2.55Channel Length


File Location: K:\20018804.00 South Leura Flood Study, Floodplain Mgt Study and Plan\Eng-Plan\Analysis\Strategic Cost Estimate\[Strategic Cost Estimate_Catch A Rev C.xls]A1-2 to A3-1Section A3-1 to JA-3


Contingency





Clear existing Landscape and stockpile m2 0 7 - 30 - Assumed 150 thk topsoil removal P205Demolish and dispose of existing road pavement wearing coarse m2 39 3 117 30 152 Assume 80 thk AC wearing coarse P206Remove and dispose of existing pipe m 13 72 936 30 1,217 Nominal trench and pipe excavation assumed P206 + P205

2b Stormwater Drainage UpgradeInstall new stormwater drainage pipe including trench backfill m 78 598 46,605 30 60,587 Dia 1050 pipe P207 + P647Install new concrete headwalls item 1 3,500 3,500 30 4,550 Allow for twin 1050 dia pipe P648Install new concrete inlet pit item 1 5,000 5,000 30 6,500 Allow for twin 1050 dia pipe P468Construct new channel widening m2 320 20 6,400 30 8,320 Channel construction assumed to be 150mm thick rock pitched, 8m wide total P646





GRAND TOTAL 88,288 116,374



Data:Pipe Dia 1.05No. of pipes 6Pipe Length 13Trench Width 3Channel Length 40


File Location: K:\20018804.00 South Leura Flood Study, Floodplain Mgt Study and Plan\Eng-Plan\Analysis\Strategic Cost Estimate\[Strategic Cost Estimate_Catch A Rev C.xls]A1-2 to A3-1Section 37 Govett St


Contingency





Clear existing Landscape and stockpile m2 100 7 650 30 845 Assumed 150 thk topsoil removal P205Demolish and dispose of existing road pavement wearing coarse m2 0 3 - 30 - Assume 80 thk AC wearing coarse P206Remove and dispose of existing pipe m 0 72 - 30 - Nominal trench and pipe excavation assumed P206 + P205

2b Stormwater Drainage UpgradeInstall new stormwater drainage pipe including trench backfill m 0 598 - 30 - Dia 1050 pipe P207 + P647Install new concrete headwalls item 0 3,500 - 30 - Allow for twin 1050 dia pipe P648Install new concrete inlet pit item 0 5,000 - 30 - Allow for twin 1050 dia pipe P468Construct new channel widening m2 0 20 - 30 - Channel construction assumed to be 150mm thick rock pitched, 8m wide total P646Construct new bund m 100 10 1,000 30 1,300 Provisional Allowance

2c ReinstatementReinstate existing road pavement m2 0 70 - 30 - Assumed 50thk AC wearing coarse on 450thk DGB base P646Reinstate existing landscaping m2 0 5 - 30 - Assumed reinstatement of existing P220


Water quality and Monitoring item 1 1,000 1,000 50 1,500 Provisional AllowanceOther agency costs item 1 500 500 50 750 Provisional Allowance





Data:Pipe Dia 0No. of pipes 0Pipe Length 0Trench Width 0Channel Length 0Bund 100


File Location: K:\20018804.00 South Leura Flood Study, Floodplain Mgt Study and Plan\Eng-Plan\Analysis\Strategic Cost Estimate\[Strategic Cost Estimate_Catch A Rev C.xls]A1-2 to A3-1Section 50 Govett St


Contingency






2b Stormwater Drainage UpgradeInstall new stormwater drainage pipe including trench backfill m 0 598 - 30 - Dia 1050 pipe P207 + P647Install new concrete headwalls item 0 3,500 - 30 - Allow for twin 1050 dia pipe P648Install new concrete inlet pit item 0 5,000 - 30 - Allow for twin 1050 dia pipe P468Construct new channel widening m2 0 20 - 30 - Channel construction assumed to be 150mm thick rock pitched, 8m wide total P646Construct new bund m 100 10 1,000 30 1,300 Provisional Allowance












Contingency





Clear existing Landscape and stockpile m2 1480 7 9,620 30 12,506 Assumed 150 thk topsoil removal P205Demolish and dispose of existing road pavement wearing coarse m2 0 3 - 30 - Assume 80 thk AC wearing coarse P206Remove and dispose of existing pipe m 0 72 - 30 - Nominal trench and pipe excavation assumed P206 + P205

2b Stormwater Drainage UpgradeInstall new stormwater drainage pipe including trench backfill m 0 458 - 30 - Dia 900 pipe P207 + P647Install new concrete headwalls item 0 3,500 - 30 - Allow for twin 900 dia pipe P648Install new concrete inlet pit item 0 5,000 - 30 - Allow for twin 900 dia pipe P468Construct new channel widening m2 1480 20 29,600 30 38,480 Channel construction assumed to be 150mm thick rock pitched, 8m wide total P646



Water quality and monitoring item 1 2,000 2,000 50 3,000 Provisional AllowanceOther agency costs item 1 1,000 1,000 50 1,500 Provisional Allowance





Data:Pipe DiaNo. of pipesPipe LengthTrench WidthChannel Length 185


File Location: K:\20018804.00 South Leura Flood Study, Floodplain Mgt Study and Plan\Eng-Plan\Analysis\Strategic Cost Estimate\[Strategic Cost Estimate_Catch B Rev C.xls]12 TennysonSection B1-1 to B1-4

Item Unit Quantity Rate $ Base Total $ Contingency (%) Estimate Including

Contingency

Comment / Reference Rawlinsons Reference




Clear existing Landscape and stockpile m2 0 7 - 30 - Assumed 150 thk topsoil removal P205Demolish and dispose of existing road pavement wearing coarse m2 51.3 3 154 30 200 Assume 80 thk AC wearing coarse P206Remove and dispose of existing pipe m 19 72 1,368 30 1,778 Nominal trench and pipe excavation assumed P206 + P205













Contingency


















Contingency





Clear existing Landscape and stockpile m2 229.5 7 1,492 30 1,939 Assumed 150 thk topsoil removal P205Demolish and dispose of existing road pavement wearing coarse m2 0 3 - 30 - Assume 80 thk AC wearing coarse P206Remove and dispose of existing pipe m 85 72 6,120 30 7,956 Nominal trench and pipe excavation assumed P206 + P205


2c ReinstatementReinstate existing road pavement m2 0 70 - 30 - Assumed 50thk AC wearing coarse on 450thk DGB base P646Reinstate existing landscaping m2 229.5 5 1,148 30 1,492 Assumed reinstatement of existing P220




GRAND TOTAL 109,119 143,455





File Location: K:\20018804.00 South Leura Flood Study, Floodplain Mgt Study and Plan\Eng-Plan\Analysis\Strategic Cost Estimate\[Strategic Cost Estimate_Catch B Rev C.xls]12 TennysonSection 22 Abbey St


Contingency






2b Stormwater Drainage UpgradeInstall new stormwater drainage pipe including trench backfill m 0 598 - 30 - Dia 1050 pipe P207 + P647Install new concrete headwalls item 0 3,500 - 30 - Allow for twin 1050 dia pipe P648Install new concrete inlet pit item 0 5,000 - 30 - Allow for twin 1050 dia pipe P468Construct new channel widening m2 0 20 - 30 - Channel construction assumed to be 150mm thick rock pitched, 8m wide total P646Construct new bund m 60 10 600 30 780 Provisional Allowance












Contingency





Clear existing Landscape and stockpile m2 0 7 - 30 - Assumed 150 thk topsoil removal P205Demolish and dispose of existing road pavement wearing coarse m2 33.15 3 99 30 129 Assume 80 thk AC wearing coarse P206Remove and dispose of existing pipe m 13 72 936 30 1,217 Nominal trench and pipe excavation assumed P206 + P205













Contingency





Clear existing Landscape and stockpile m2 413.1 7 2,685 30 3,491 Assumed 150 thk topsoil removal P205Demolish and dispose of existing road pavement wearing coarse m2 0 3 - 30 - Assume 80 thk AC wearing coarse P206Remove and dispose of existing pipe m 162 72 11,664 30 15,163 Nominal trench and pipe excavation assumed P206 + P205


2c ReinstatementReinstate existing road pavement m2 0 70 - 30 - Assumed 50thk AC wearing coarse on 450thk DGB base P646Reinstate existing landscaping m2 413.1 5 2,066 30 2,685 Assumed reinstatement of existing P220




GRAND TOTAL 187,145 244,888







Contingency





Clear existing Landscape and stockpile m2 120 7 780 30 1,014 Assumed 150 thk topsoil removal P205Demolish and dispose of existing road pavement wearing coarse m2 0 3 - 30 - Assume 80 thk AC wearing coarse P206Remove and dispose of existing pipe m 0 72 - 30 - Nominal trench and pipe excavation assumed P206 + P205


2c ReinstatementReinstate existing road pavement m2 0 70 - 30 - Assumed 50thk AC wearing coarse on 450thk DGB base P646Reinstate existing landscaping m2 120 5 600 30 780 Assumed reinstatement of existing P220







Data:Pipe Dia 0No. of pipes 0Pipe Length 0Trench Width 0Channel Length 15




Contingency


















Contingency





Clear existing Landscape and stockpile m2 660 7 4,290 30 5,577 Assumed 150 thk topsoil removal P205Demolish and dispose of existing road pavement wearing coarse m2 0 3 - 30 - Assume 80 thk AC wearing coarse P206Remove and dispose of existing pipe m 200 72 14,400 30 18,720 Nominal trench and pipe excavation assumed P206 + P205


2c ReinstatementReinstate existing road pavement m2 0 70 - 30 - Assumed 50thk AC wearing coarse on 450thk DGB base P646Reinstate existing landscaping m2 660 5 3,300 30 4,290 Assumed reinstatement of existing P220




GRAND TOTAL 288,490 376,637







Contingency
















File Location: K:\20018804.00 South Leura Flood Study, Floodplain Mgt Study and Plan\Eng-Plan\Analysis\Strategic Cost Estimate\[Strategic Cost Estimate_Catch B Rev C.xls]12 TennysonSection 12 Tennyson


Contingency






2b Stormwater Drainage UpgradeInstall new stormwater drainage pipe including trench backfill m 0 598 - 30 - Dia 1050 pipe P207 + P647Install new concrete headwalls item 0 3,500 - 30 - Allow for twin 1050 dia pipe P648Install new concrete inlet pit item 0 5,000 - 30 - Allow for twin 1050 dia pipe P468Construct new channel widening m2 0 20 - 30 - Channel construction assumed to be 150mm thick rock pitched, 8m wide total P646Construct new bund m 80 10 800 30 1,040 Provisional Allowance










File Location: K:\20018804.00 South Leura Flood Study, Floodplain Mgt Study and Plan\Eng-Plan\Analysis\Strategic Cost Estimate\[Strategic Cost Estimate_Catch C Rev C.xls]C1-6 to C1-7Section C1-1 to C1-2


Contingency






2b Stormwater Drainage UpgradeInstall new stormwater drainage pipe including trench backfill m 11 171 1,876 30 2,438 Dia 450 pipe P207 + P647Install new concrete headwalls item 2 350 700 30 910 Allow for twin 450 dia pipe P648Install new concrete inlet pit item 0 1,500 - 30 - Allow for twin 450 dia pipe P468Construct new channel widening m2 0 20 - 30 - Channel construction assumed to be 150mm thick rock pitched, 8m wide total P646

2c ReinstatementReinstate existing road pavement m2 11.55 70 809 30 1,051 Assumed 50thk AC wearing coarse on 450thk DGB base P646Reinstate existing landscaping m2 0 5 - 30 - Assumed reinstatement of existing P220









File Location: K:\20018804.00 South Leura Flood Study, Floodplain Mgt Study and Plan\Eng-Plan\Analysis\Strategic Cost Estimate\[Strategic Cost Estimate_Catch C Rev C.xls]C1-6 to C1-7Section C1-2 TO C1-3


Contingency


















Contingency






2b Stormwater Drainage UpgradeInstall new stormwater drainage pipe including trench backfill m 22 318 6,985 30 9,081 Dia 675 pipe P207 + P647Install new concrete headwalls item 2 865 1,730 30 2,249 Allow for twin 675 dia pipe P648Install new concrete inlet pit item 0 1,500 - 30 - Allow for twin 675 dia pipe P468Construct new channel widening m2 0 20 - 30 - Channel construction assumed to be 150mm thick rock pitched, 8m wide total P646












Contingency







2c ReinstatementReinstate existing road pavement m2 0 70 - 30 - Assumed 50thk AC wearing coarse on 450thk DGB base P646Reinstate existing landscaping m2 60 5 300 30 390 Assumed reinstatement of existing P220











Contingency


















Contingency





Clear existing Landscape and stockpile m2 0 7 - 30 - Assumed 150 thk topsoil removal P205Demolish and dispose of existing road pavement wearing coarse m2 46.5 3 140 30 181 Assume 80 thk AC wearing coarse P206Remove and dispose of existing pipe m 15.5 72 1,116 30 1,451 Nominal trench and pipe excavation assumed P206 + P205









Data:Pipe Dia 1.05No. of pipes 2Pipe Length 15.5Trench Width 3Channel Length




Contingency





Clear existing Landscape and stockpile m2 0 7 - 30 - Assumed 150 thk topsoil removal P205Demolish and dispose of existing road pavement wearing coarse m2 18 3 54 30 70 Assume 80 thk AC wearing coarse P206Remove and dispose of existing pipe m 15 72 1,080 30 1,404 Nominal trench and pipe excavation assumed P206 + P205

2b Stormwater Drainage UpgradeInstall new stormwater drainage pipe including trench backfill m 15 226 3,383 30 4,397 Dia 600 pipe P207 + P647Install new concrete headwalls item 1 495 495 30 644 Allow for twin 600 dia pipe P648Install new concrete inlet pit item 0 1,500 - 30 - Allow for twin 600 dia pipe P468Construct new channel widening m2 0 20 - 30 - Channel construction assumed to be 150mm thick rock pitched, 8m wide total P646












Contingency





Clear existing Landscape and stockpile m2 0 7 - 30 - Assumed 150 thk topsoil removal P205Demolish and dispose of existing road pavement wearing coarse m2 33 3 99 30 129 Assume 80 thk AC wearing coarse P206Remove and dispose of existing pipe m 10 72 720 30 936 Nominal trench and pipe excavation assumed P206 + P205

2b Stormwater Drainage UpgradeInstall new stormwater drainage pipe including trench backfill m 40 171 6,820 30 8,866 Dia 450 pipe P207 + P647Install new concrete headwalls item 2 3,500 7,000 30 9,100 Allow for multiple 450 dia pipe P648Install new concrete inlet pit item 0 5,000 - 30 - Allow for multiple 450 dia pipe P468Construct new channel widening m2 0 20 - 30 - Channel construction assumed to be 150mm thick rock pitched, 8m wide total P646












Contingency


















Contingency











GRAND TOTAL 90,868 119,729





File Location: K:\20018804.00 South Leura Flood Study, Floodplain Mgt Study and Plan\Eng-Plan\Analysis\Strategic Cost Estimate\[Strategic Cost Estimate_Catch D Rev C.xls]39Section D-4 to D-5


Contingency






2b Stormwater Drainage UpgradeInstall new stormwater drainage pipe including trench backfill m 11 318 3,493 30 4,540 Dia 675 pipe P207 + P647Install new concrete headwalls item 2 865 1,730 30 2,249 Allow for twin 675 dia pipe P648Install new concrete inlet pit item 0 1,500 - 30 - Allow for twin 675 dia pipe P468Construct new channel widening m2 0 20 - 30 - Channel construction assumed to be 150mm thick rock pitched, 8m wide total P646










File Location: K:\20018804.00 South Leura Flood Study, Floodplain Mgt Study and Plan\Eng-Plan\Analysis\Strategic Cost Estimate\[Strategic Cost Estimate_Catch E Rev C.xls]59Section E1-6 to E1-17


Contingency





Clear existing Landscape and stockpile m2 0 7 - 30 - Assumed 150 thk topsoil removal P205Demolish and dispose of existing road pavement wearing coarse m2 405 3 1,215 30 1,580 Assume 80 thk AC wearing coarse P206Remove and dispose of existing pipe m 150 72 10,800 30 14,040 Nominal trench and pipe excavation assumed P206 + P205






GRAND TOTAL 138,990 182,287







Contingency





Clear existing Landscape and stockpile m2 528 7 3,432 30 4,462 Assumed 150 thk topsoil removal P205Demolish and dispose of existing road pavement wearing coarse m2 0 3 - 30 - Assume 80 thk AC wearing coarse P206Remove and dispose of existing pipe m 160 72 11,520 30 14,976 Nominal trench and pipe excavation assumed P206 + P205






GRAND TOTAL 150,692 197,500







Contingency






2b Stormwater Drainage UpgradeInstall new stormwater drainage pipe including trench backfill m 50 318 15,875 30 20,638 Dia 675 pipe P207 + P647Install new concrete headwalls item 2 865 1,730 30 2,249 Allow for twin 675 dia pipe P648Install new concrete inlet pit item 1 2,000 2,000 30 2,600 Allow for twin 675 dia pipe P468Construct new channel widening m2 0 20 - 30 - Channel construction assumed to be 150mm thick rock pitched, 8m wide total P646










File Location: K:\20018804.00 South Leura Flood Study, Floodplain Mgt Study and Plan\Eng-Plan\Analysis\Strategic Cost Estimate\[Strategic Cost Estimate_Catch F Rev C.xls]F1-6 to F1-9Section F1-12 to F1-1


Contingency







2c ReinstatementReinstate existing road pavement m2 12.6 70 882 30 1,147 Assumed 50thk AC wearing coarse on 450thk DGB base P646Reinstate existing landscaping m2 0 5 - 30 - Assumed reinstatement of existing P220











Contingency


















Contingency





Clear existing Landscape and stockpile m2 135 7 878 30 1,141 Assumed 150 thk topsoil removal P205Demolish and dispose of existing road pavement wearing coarse m2 0 3 - 30 - Assume 80 thk AC wearing coarse P206Remove and dispose of existing pipe m 0 72 - 30 - Nominal trench and pipe excavation assumed P206 + P205









Data:Pipe Dia 0No. of pipes 0Pipe Length 0Trench Width 0Channel Length 45Bund




Contingency





Clear existing Landscape and stockpile m2 432 7 2,808 30 3,650 Assumed 150 thk topsoil removal P205Demolish and dispose of existing road pavement wearing coarse m2 54 3 162 30 211 Assume 80 thk AC wearing coarse P206Remove and dispose of existing pipe m 160 72 11,520 30 14,976 Nominal trench and pipe excavation assumed P206 + P205


2c ReinstatementReinstate existing road pavement m2 54 70 3,780 30 4,914 Assumed 50thk AC wearing coarse on 450thk DGB base P646Reinstate existing landscaping m2 432 5 2,160 30 2,808 Assumed reinstatement of existing P220




GRAND TOTAL 196,830 257,479







Contingency


















Contingency











GRAND TOTAL 120,288 157,974





File Location: K:\20018804.00 South Leura Flood Study, Floodplain Mgt Study and Plan\Eng-Plan\Analysis\Strategic Cost Estimate\[Strategic Cost Estimate_Catch F Rev C.xls]F1-6 to F1-9Section F2-1 to F1-4/F2-2 Channel Improvement


Contingency
















File Location: K:\20018804.00 South Leura Flood Study, Floodplain Mgt Study and Plan\Eng-Plan\Analysis\Strategic Cost Estimate\[Strategic Cost Estimate_Catch F Rev C.xls]F1-6 to F1-9Section F2-1 to F1-4/F2-2 Bunding


Contingency









Water quality and Monitoring item 1 2,000 1,000 50 1,500 Provisional AllowanceOther agency costs item 1 1,000 500 50 750 Provisional Allowance






Documents

South Leura Floodplain Management Report FinalJan09...Council does not have an existing flood policy however two relevant planning documents make reference to land subject to inundation