CHAPTER G9: DEVELOPMENT ON FLOOD PRONE LANDdcp2014.shoalhaven.nsw.gov.au/sites/dcp2014.shoalhaven.nsw.gov.au... · Chapter G9: Development on Flood Prone Land Table of Changes

NOTE: This Chapter should not be read in isolation. You may need to consider other chapters of this DCP when preparing your application.

CHAPTER G9: DEVELOPMENT ON FLOOD PRONE LAND

Shoalhaven Development Control Plan 2014

Chapter G9: Development on Flood Prone Land

Table of Changes

Old Section

New Section

Recommended Change Reason

1 - Insert note to advise reader of Council’s recently adopted sea level rise benchmarks: “Please note that Council has adopted new sea level rise benchmarks and will be revising its coastal hazard and flood mapping to incorporate these new benchmarks.”

To advise readers of Council’s intention to revise this chapter in the future, taking into consideration the recently adopted sea level rise benchmarks.

Schedule 5 Part D

- Remove the site specific flood related development controls from the table in Schedule 5 Part D, for the properties: 3, 7, 9, 11, 42, 59 Adelaide Street; 59 Haiser Road, 2 Keith Avenue, 1 Church Street and 68, 70, 76 Greens Road in Greenwell Point.

This is in response to the outcomes of the Greenwell Point Floodplain Risk Management Options Feasibility Study and its deletion a resolution of Council D15/39636.



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Contents

1 Purpose ........................................................................................................................ 4

2 Application .................................................................................................................... 4

3 Context ......................................................................................................................... 4

4 Objectives ..................................................................................................................... 5

5 Controls ........................................................................................................................ 5

5.1 General ................................................................................................................... 5

5.2 Fill or Excavation on the Floodplain ........................................................................ 8

5.3 Subdivision in the Floodplain .................................................................................. 9

6 Advisory Information ................................................................................................... 10

6.1 Considerations when preparing a development application .................................. 10

6.1.1 My proposal is small scale – do I still need consent? ........................................... 10

6.1.2 What type of flood information is available? ......................................................... 10

6.1.3 What sections of the Chapter apply to my application? ........................................ 11

6.2 How to address the requirements of this Chapter ................................................. 12

6.3 Management of development on Flood Prone Land ............................................. 13

6.3.1 Flood Prone Land: The Policy Context ................................................................. 13

6.3.2 Flood Prone Land Policy (1984) ........................................................................... 13

6.3.3 NSW Floodplain Development Manual (2005) ...................................................... 14

6.4 Flood Planning Concepts ...................................................................................... 17

6.4.1 Flood Planning Area ............................................................................................. 17

6.4.2 Flood Planning Levels and Freeboard .................................................................. 18

6.4.3 Climate Change .................................................................................................... 19

6.5 Development application documents .................................................................... 20

6.5.1 Flood Compliance Report ..................................................................................... 20

6.5.2 Other additional development application documents .......................................... 22

6.6 Flood DCP Compliance Report Checklist and Schedules .................................... 24

7 Other legislation or policies you may need to check ................................................... 24

8 Flood Compliance Report Checklist ............................................................................ 25

Schedule 1 – Land Use Categories ................................................................................... 26



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Schedule 2 – Flood Information Enquiries and Flood Certificates ..................................... 29

Schedule 3 – Technical Reporting Requirements .............................................................. 31

Schedule 4 – Flood Proofing Guidelines ............................................................................ 37

Schedule 5 – Flood Related Development Controls – Site Specific as per the adopted Floodplain Risk Management Plan .................................................................................... 42

Schedule 6 – Flood Related Development Controls - Generic ........................................... 51

Figures

Figure 1: Floodplain Risk Management Process- Source: 2005 NSW Floodplain Development Manual ......................................................................................................... 15 Figure 2: Floodplain Aerial View ........................................................................................ 17

Figure 3: Cross Section through floodplain – hydraulic categories within flood planning area.................................................................................................................................... 18 Figure 4: Coastal Flooding Consideration in Development Assessment Process ............. 19 Figure 5: Procedure for obtaining a Flood Certificate from Council ................................... 30

Amendment history

Version Number Date Adopted by Council Commencement Date Amendment Type

1 14 October 2014 22 October 2014 New

2 Draft



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1 Purpose

The purpose of this Chapter is to provide information and development controls needed to

prepare and assess development applications on flood prone land.

Notes:

For this purpose of this Chapter, ‘flood prone land’ means the land susceptible to flooding by the probable maximum flood event (that is, land within the floodplain) as indicated on the map marked "Flood Prone Land" deposited in the office of the Council as amended from time to time.

Please note that Council has adopted new sea level rise benchmarks and will be revising its coastal hazard and flood mapping to incorporate these new benchmarks.

2 Application

This Chapter applies to all development on flood prone land within Shoalhaven.

Note: Proposed development on land outside the flood planning area (see Figure 2) may still be located on land which is classified as flood prone land if it is below the probable maximum flood (PMF) level.

Flood prone land is described in detail in Section 6 under the heading Flood Planning Concepts. Development controls apply for development in the flood planning area. Additional controls apply to ‘Buildings and activities requiring special evacuation consideration’ (as per Schedule 6) up to the probable maximum food event.

In cases where a site is classified as partially flood affected, it is strongly recommended to only consider development on the flood free portion of the allotment.

3 Context

The NSW Flood Prone Land Policy provides a framework for Council to manage flood prone land. Council is required under the Environmental Planning and Assessment Act 1979, and in various environmental planning instruments including the Shoalhaven LEP 2014, to ensure that due regard is given to the effect of natural hazards upon development.

Note: Hazard is a source of potential harm or a situation with the potential to cause loss. In relation to this Chapter the hazard is flooding which has the potential to cause damage to the community. Hazard can be categorised as high hazard and low hazard.

In high hazard areas there is a possible danger to personal safety, evacuation by trucks is difficult, able bodied adults would have difficulties wading to safety, and flooding can cause potential significant structural damage to buildings.



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In low hazard areas, trucks could evacuate people and their possessions and able bodied adults would have little difficulty in wading to safety.

A flood is defined by the NSW Floodplain Development Manual as:

a relatively high stream flow which overtops the natural or artificial banks in any part of a stream, river, estuary, lake or dam, and/or

local overland flooding associated with major drainage before entering a watercourse, and/or

coastal inundation resulting from super-elevated sea levels and/or waves overtopping coastline defences excluding tsunami

Local overland flooding means inundation by local runoff rather than overbank discharge from a stream, river, estuary, lake or dam.

Annual exceedance probability (AEP) means the chance of a flood of a given or larger size occurring in any one year, usually expressed as a percentage.

4 Objectives

The objectives are to:

i. Reduce risk to life and property resulting from floods;

ii. Ensure that the impacts of the full range of flood sizes up to and including the PMF

are considered when assessing development on flood prone land;

iii. Ensure that the impact of climate change is considered when assessing

development on flood prone land:

iv. Ensure the future use of flood prone land does not cause undue distress to

individuals or unduly increases potential flood liability to individuals or the

community; and

v. Incorporate site specific floodplain management recommendations from local

floodplain risk management plans into Council’s overall planning framework.

Note: Risk means the chance of something happening that will have an impact. It is measured in terms of consequences and probability (likelihood). In the context of this Chapter, it is the likelihood of consequences arising from the interaction of floods, communities and the environment.

5 Controls

5.1 General

The specific objectives are to:

i. Minimise risk to life and damage to property by controlling development on flood

prone land;



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ii. To ensure that the impacts of the full range of flood sizes up to and including the

PMF are considered when assessing development on flood prone areas within

Shoalhaven;

iii. To ensure that development does not have a significant impact on flood behaviour,

people’s safety, surrounding properties and structures, and the natural environment;

iv. To ensure that the effects of climate change are considered when assessing

development in flood prone land within Shoalhaven;

v. To ensure that development on the floodplain is consistent with the NSW Flood

Prone Land Policy and NSW Floodplain Development Manual;

vi. To ensure that developers and the community are conscious of the potential flood

hazard and consequent risk associated with the use and development of land within

the floodplain;

vii. To protect the integrity of floodplains and floodways, including riparian vegetation,

fluvial geomorphologic environmental processes and water quality;

viii. To ensure that all land uses and essential services are appropriately sited and

designed in recognition of all potential floods; and

ix. To ensure that development on flood prone land does not place an unacceptable

financial burden on landowners or the community.

Performance Criteria Acceptable Solutions

P1 Development or work on flood

prone land will meet the

following:

The development will not

increase the risk to life or

safety of persons during a

flood event on the

development site and

adjoining land.

The development or work

will not unduly restrict the

flow behaviour of

floodwaters.

The development or work

will not unduly increase the

level or flow of floodwaters

or stormwater runoff on

land in the vicinity. The

development or work will

not exacerbate the adverse

consequences of

floodwaters flowing on the

land with regard to erosion,

A1.1 The development satisfies the requirements as shown

in the planning matrix at Schedule 6 including climate

change considerations (See section 7.3); and

A1.2 Buildings and structures are constructed in accordance

with the flood proofing guidelines (see Schedule 4); and

Note: Flood proofing means a combination of measures incorporated in the design, construction and alteration of individual buildings or structures subject to flooding, to reduce or eliminate flood damages.

A1.3 Buildings and structures are constructed in accordance

with the Building Code of Australia - Construction of

Buildings in Flood Hazard Areas – Standard 2012.

The controls in this Chapter are to be used in instances

where this Chapter specifies more stringent controls;

and

Buildings and structures are designed to withstand the forces of flood waters in accordance with best practice engineering standards; or

A1.4 Where appropriate structures are designed to collapse

under the force of water to not obstruct the flood flow,

but are sufficiently secured to not become floating

debris and to not endanger people or animals; or



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siltation and destruction of

vegetation.

The structural

characteristics of any

building or work that are the

subject of the application

are capable of withstanding

flooding in accordance with

the requirements of the

Council.


become unsafe during

floods or result in moving

debris that potentially

threatens the safety of

people or the integrity of

structures.

Potential damage due to

inundation of proposed

buildings and structures is

minimised.


obstruct escape routes for

both people and stock in

the event of a flood.


unduly increase

dependency on emergency

services.

Interaction of flooding from

all possible sources has

been taken into account in

assessing the proposed

development against risks

to life and property resulting

from any adverse hydraulic

impacts.


adversely affect the

integrity of floodplains and

A1.5 Openings in structures such as fences or the like will be

provided below the flood planning level to allow free

flow of water; and where relevant;

A1.6 Building foundations are designed by a suitably

qualified geotechnical engineer to be suitable for

grounds with potentially reduced bearing capacity

under flooding conditions; and

Note: Bearing capacity is defined in geotechnical engineering as

the capacity of soil to support the loads applied to the ground, such as the loads from housing foundations for example

A1.7 The development complies with ecological sustainable

development principles, taking into account floodplain

ecology and integrity; and

A1.8 A report demonstrating that all performance criteria

have been met is supplied with the development

application.



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floodways, including

riparian vegetation, fluvial

geomorphologic

environmental processes

and water quality.

Note: Fluvial geomorphology is the branch of geology that examines the formation and structure of the features of the surface of the earth which is created by flowing rivers

5.2 Fill or Excavation on the Floodplain

The specific objective is to:

i. Ensure that filling or excavation within the floodplain does not have a significant

impact on flood behaviour, conveyance and storage capacity, as well as

surrounding properties or structures and the environment in the specific area where

the development is proposed.

Note: Conveyance is a direct measure of the flow carrying capacity

of a particular cross-section of a stream or stormwater channel. (For

example, if the conveyance of a channel cross-section is reduced by

half, then the flow carrying capacity of that channel cross-section will

also be halved).


P2 Filling or excavation on flood prone

land will meet the following:

High hazard floodway areas are

kept free of fill and/or obstructions.

The proposed fill or excavation will

not unduly restrict the flow

behaviour of floodwaters.


not unduly increase the level or flow

of floodwaters or stormwater runoff

on land in the vicinity, including

adjoining land.


not exacerbate erosion, siltation

and destruction of vegetation

caused by floodwaters flowing on

A2.1 The development satisfies the requirements as

shown in the planning matrix at Schedule 6.

A2.2 The proposed fill volume occupies less than

the 2050 1% of the available 20%, 5% and 1%

AEP flood volume on the development site and

does not create a depth exceeding 1 metre

above natural ground level or require more

than 250 cubic metres of filling materials.

A2.3 The proposed fill and excavation does not

adversely affect neighbouring properties or the

overall flood behaviour and flood storage

volume.

A2.4 The proposed fill is used only for the purpose

of filling a local depression beneath the

confines of a building within an existing

residential/ commercial area.



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the land.


not be carried out on flood prone

land if sufficient flood free area is

available for development within the

subject property.

The proposed excavation does not

create new habitable rooms, non-

habitable storage areas or carparks

with floor levels below the existing

ground level.

Note: Habitable room has the same meaning as the Building Code of Australia. This is a room used for normal domestic activities, other than a bathroom, laundry, toilet, pantry, walk in wardrobe, hallway, lobby, clothes drying room or other space of a specialised nature that is not occupied frequently or for extended periods.

5.3 Subdivision in the Floodplain

The specific objective is to:

i. Ensure that the creation of new lots does not increase potential flood risks to land

owners or the community.


P3.1 Potential development as a

consequence of a subdivision

proposal must be able to be

undertaken in compliance with this

Chapter.

P3.2 The proposed subdivision will not

create new lots that are affected by

a high hazard area, or floodway in

today’s flood conditions or in

climate change conditions up to the

year 2100.

P3.3 The proposed subdivision will not

increase the potential population

density in any areas (flood prone or

flood free) with restricted

evacuation access

A3.1 The development satisfies the requirements

as shown in the planning matrix at Schedule

6; and

A3.2 Flood conditions for the year 2100, which

include sea level rise of 0.9m, are used.



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P4 Lots are provided with flood free

access.

A4.1 The proposed access to the lots

demonstrates compliance with Chapter G:

Development on Flood Prone Land.

A4.2 All drainage design to be in accordance with

Council’s Engineering Design Specifications,

Chapter 5.

P5 Culverts, roads and other drainage

structures are designed for 20% AEP

storm event.

A5.1 Culverts and small bridges within rights of way

are designed for the 20% AEP storm event

and designed to withstand the 1% AEP flow.

A5.2 Overflow over roads is in accordance with

velocity and depth criteria.

P6 Bridges to be designed for 1% AEP

storm event.

A6.1 Bridge design to conform to AUSTROADS -

Bridge Design Code 1992 and Waterway

Design, 1994.

6 Advisory Information

6.1 Considerations when preparing a development application

In preparing a development application, you will need to make investigations in order to

ensure your application meets Council’s requirements for development on flood prone

land. These considerations are:

6.1.1 My proposal is small scale – do I still need consent?

Some small scale developments such as some fences or drainage works and the like may

not require development consent, however, on flood prone land careful consideration is

needed to ensure that such development does not have a significant impact in relation to

flooding. Please check with Council whether you need consent or meet specific conditions

to minimise flood impact.

6.1.2 What type of flood information is available?

The controls that apply to development on flood prone land will depend on the hydraulic

and hazard categorisations for a site, which can only be determined if flood information is

available. Due to the large number of water bodies within Shoalhaven, the information that

is available for different catchments varies significantly and could range from historical

information to very detailed flood modelling data formulated as part of the floodplain risk

management process.



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It is necessary to determine the type of information available for your site, including

whether or not a floodplain risk management plan has been adopted for your area. This

can be done by checking the most up to date flood maps on Council’s website at

www.shoalhaven.nsw.gov.au

For areas where sufficient flood information is available, you will be able to obtain a site

specific flood certificate from Council (please refer to Schedule 2 for information on how to

do this)

There are a number of catchments within Shoalhaven that have not been the subject of a

detailed flood study and will not be studied in the near future. Any development

application proposing works within such an area must therefore be accompanied by a

flood assessment report undertaken by a suitably qualified hydraulic engineer (please refer

to Schedule 3).

6.1.3 What sections of the Chapter apply to my application?

Depending on the type of development proposed as well as the type of flood information

that is available for a particular site, the development application will be assessed against

different sections within the Chapter:

Flood prone land where a floodplain risk management plan has not been

adopted

For areas where Council has not adopted a floodplain risk management plan,

generic development controls as contained in Section 9 and Schedule 6 will apply.

These controls will also apply if the property is within 40m of a watercourse or within

10m of a major drainage system, overland flood path or drainage easement. Please

check www.shoalhaven.nsw.gov.au for up to date information on which areas

currently do not have a floodplain risk management plan.

Land where a floodplain risk management plan has been adopted.

For areas where Council has adopted a floodplain risk management plan, site

specific controls will apply in addition to generic controls as mentioned above.

These specific controls are contained in Schedule 5. Please check

www.shoalhaven.nsw.gov.au for up to date information on which areas currently do

have an adopted floodplain risk management plan.

http://shoalhaven.nsw.gov.au/




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6.2 How to address the requirements of this Chapter

To determine the flood-based development controls that are relevant to a proposed

development and to prepare your submission to Council, the following steps should be

taken:

Step 1:

Read the background information in Section 6 of this Chapter including flood

prone land: The policy context and flood planning concepts.

Step 2:

Determine what flood information is available for your site and whether or not

Council has adopted a floodplain risk management plan for the area via


If flood information is available, obtain a flood certificate. If no flood information is

available from Council, you may be required to engage a suitably qualified

engineer recognised under the National Professional Engineers Register (NPER)

to undertake a flood assessment report. Refer to Schedule 4 for more

information on what is required for such an assessment.

Step 3:

Determine the land use category that best fits the proposed development,

keeping in mind that your development may relate to more than one land use

category for example retail outlet plus ancillary car park (refer to Schedule 3 for

assistance).

If a proposed type of development does not fit within one of the categories, the

development will be assessed on a merit basis, however you will be required to

provide additional supporting information as determined by Council. Confirm the

chosen land use category with Council.

Step 4:

From your flood certificate or flood assessment report determine which part of the

floodplain the site is located on. In this regard, the categories are:

i. Within the flood planning area (refer to Figure 2):

a) High Hazard floodway

b) High Hazard flood storage area

c) High Hazard flood fringe

d) Low Hazard floodway

e) Low Hazard flood storage area

f) Low Hazard flood fringe

ii. Outside the flood planning area but within the flood prone area, that is

below the PMF level (refer to Figure 2).

Step 5:

Review the appropriate development performance criteria in Section 5 and

Schedule 6 and determine which criteria are relevant to your proposal.




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Step 6: If a floodplain risk management plan has been adopted for your area, review all

additional development controls in Schedule 4 and determine which of these

additional criteria are relevant to your proposal. If site specific controls contradict

generic controls determined in Step 5, the site specific controls will prevail.

Step 7:

Compile your flood DCP compliance report for the proposed development, as

outlined in this Chapter.

Step 8:

Ensure that you have included all required documentation with your development

application. Refer to checklist within this Chapter.

Step 9: Submit all information to Council for assessment.

6.3 Management of development on Flood Prone Land

6.3.1 Flood Prone Land: The Policy Context

This Chapter is based on best practice principles as set out in the NSW Flood Prone Land

Policy and the NSW Floodplain Development Manual. The following provides a summary

of the contents of these documents and shows how this Chapter sits within the overall

policy framework.

6.3.2 Flood Prone Land Policy (1984)

The primary objective of the NSW Flood Prone Land Policy is to reduce the impact of

flooding and flood liability on individual owners and occupiers of flood prone land, and to

reduce private and public losses resulting from floods.

At the same time, the policy recognises the benefits flowing from the limited use,

occupation and development of flood prone land.

The policy promotes the use of a merit approach which balances social, economic,

environmental and flood risk parameters to determine whether a particular development or

use of the floodplain is appropriate and sustainable.

In this way the policy avoids the unnecessary sterilisation of flood prone land. Equally it

ensures that flood prone land is not the subject of uncontrolled development inconsistent

with its exposure to flooding.

The policy requires that:

Both mainstream and overland flooding be addressed in the preparation and

implementation, by councils, of strategically generated floodplain risk management

plans;



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The impact of flooding and flood liability on existing developed areas identified in

floodplain risk management plans be reduced by flood mitigation works and

measures, including on-going emergency management measures, the raising of

houses where appropriate and by development controls; and

The potential for flood losses in all areas proposed for development or

redevelopment be contained by the application of ecologically sensitive planning

and development controls.

6.3.3 NSW Floodplain Development Manual (2005)

The NSW Floodplain Development Manual 2005 (the Manual) is concerned with the

management of the consequences of flooding as they relate to the human occupation of

the floodplain for urban development and agricultural production. The Manual addresses

flood risk. The Manual requires that management decisions taken in respect of the human

occupation of the floodplain need to satisfy the social and economic needs of the

community, as well as being compatible with the maintenance or enhancement of the

natural ecosystems that the floodplain sustains.

The Manual supports the NSW Flood Prone Land Policy in providing for the development

of sustainable strategies for managing human occupation and use of the floodplain

considering risk management principles. These are based upon a hierarchy of avoidance,

minimisation (using planning controls) and mitigation works.

The Manual states that the most effective means of achieving sound flood risk

management outcomes is to formulate and implement management plans through the

floodplain risk management process as shown in Figure 1 below. Due to the level of detail

required; technical studies and other complexities, the process generally takes several

years to be completed.



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Figure 1: Floodplain Risk Management Process- Source: 2005 NSW Floodplain Development Manual

A management plan generally involves a mix of options as it is unusual for a single

management option to manage the full range of flood risk. Determining the optimum mix of

measures can require complex studies, exercise of professional judgement and extensive

community consultation. Typical options considered are:

a) Property modification measures such as development controls in new areas or

voluntary purchase and house raising in developed areas;

b) Response modification measures such as evacuation and associated operational

logistics; and

c) Flood modification measures such as levees or bypass channels.

Note: Bypass channels redirect a portion of floodwater away from areas under threat from flooding, and so reduce flood levels along the channel downstream of the diversion.

As per the Flood Prone Land Policy, the Manual provides for the application of a “merit

approach” for decisions on the future use of the floodplain. This is an approach which

weighs social, economic, ecological and cultural impacts of land use options for different

flood prone areas together with flood damage, hazard and behaviour implications, and

environmental protection and wellbeing of the State’s rivers and floodplains.

Floodplain

Risk

Management

Committee

Data

Collection

Flood

Study

Floodplain

Risk

Management

Study

Floodplain

Risk

Management

Plan

Implementation

of Plan

Established by the

Council, must include

community groups

and state agency

specialists

Compilation of

existing data and

collection of

additional data.

Usually

undertaken by

consultants

appointed by the

Council.

Defines the nature

and extent of the

flood problem, in

technical rather

than map form.

Usually

undertaken by

consultants

appointed by the

Council.

Determines

options in

consideration of

social, ecological

and economic

factors relating to

flood risk. Usually

undertaken by

consultants

appointed by the

Council.

Preferred options

publicly exhibited

and subject to

revision in light of

responses. Formally

approved by the

Council after public

exhibition and any

necessary revisions

due to public

comments.

Flood, response and

property modification

measures including

mitigation works,

planning controls,

flood warnings, flood

readiness and

response plans,

environmental

rehabilitation,

ongoing data

collection and

monitoring.



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This "merit approach" operates at two levels:

i. the strategic level; and

ii. the site specific level.

At the strategic level, the "merit approach" allows for consideration of social, economic,

ecological, cultural and flooding issues to determine strategies for the management of

continuing and future flood risk. For example, floodplain risk management plans and

Council environmental planning instruments such as the Shoalhaven LEP 2014.

At a site specific level, the "merit approach" involves consideration of the best way of

assessing development allowable under the floodplain risk management plans, the local

floodplain risk management policy and environmental planning Instruments. These

considerations include site specific issues such as minimum floor levels, building location

within the site, access to the site, structural stability, and flood proofing etc, as appropriate.



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6.4 Flood Planning Concepts

6.4.1 Flood Planning Area

The criteria within this Chapter for determining development applications for development

on flood prone land are structured in recognition that different controls are applicable to

different land uses and levels of potential flood inundation and hazard. The following

hydraulic and hazard classifications apply:

a) Within the flood planning area (refer to Figure 2)

Figure 2: Floodplain Aerial View

b) Outside the flood planning area but within the flood prone area, that is below the

PMF level



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Figure 3: Cross Section through floodplain – hydraulic categories within flood planning area

6.4.2 Flood Planning Levels and Freeboard

Flood planning levels are the combination of adopted design flood level plus freeboard.

They determine the area of land (flood planning area) on which specific flood related

development controls will be imposed. They are set during the floodplain risk

management process and are based on a detailed understanding of flood behaviour

across the full range of floods, their probability of occurrence and the social, economic and

ecological consequences associated with those floods.

Freeboard is a factor of safety applied as an additional height to identified flood levels.

The purpose of a freeboard is to cater for uncertainties in the estimation of flood levels

across the floodplain due to wave action, localised hydraulic behaviour such as eddies and

embankment or levee settlement and some of the uncertainties associated with estimating

climate change impacts. The freeboard and flood planning levels can be seen in Figure 3.

Note: Eddies are small whirls caused by movement in a flowing

stream of liquid.

Different development controls apply to different land uses, levels of potential flood

inundation and hazard within the flood planning area. The following hydraulic categories

apply:

Flood fringe

Flood storage area

Floodway



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6.4.3 Climate Change

Climate change is expected to have impacts on sea levels and rainfall intensities, both of

which may influence flood behaviour at specific locations. Potential impacts are therefore

considered during the floodplain risk management process and are taken into account

when design flood levels for each individual catchment are determined.

Current NSW Government legislation requires climate change to be considered.

Figure 4 shows how the 1% AEP flood levels will incrementally factor in sea level rise

planning benchmarks:

Figure 4: Coastal Flooding Consideration in Development Assessment Process Source: NSW Coastal Planning Guideline: Adapting to Sea Level Rise 2010

Currently no relevant planning benchmarks have been adopted by Government in relation

to rainfall intensity changes. However, NSW State Government guidelines recommend

doing a sensitivity analysis using nominal increases in rainfall intensities. If a flood

assessment report is required, the sensitivity analysis is to be done at this time.

In order to meet the above requirements, the following is to be considered.

For new building applications below 4m AHD, the impact of a 0.4m sea level rise is

to be included when determining the flood planning level. This can be done by

adding 0.4m to identified flood levels or through a flood assessment report which

includes 0.4m sea level rise increase in design flood calculations.



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For applications for subdivision on land below 4m AHD, the impact of a 0.9m sea

level rise is to be included in their design. This can be done by adding 0.9m to

identified flood levels or through a flood assessment report which includes 0.9m sea

level rise increase in design flood calculations.

Note: Australian height datum (AHD) is a common national surface

level datum corresponding approximately to mean sea level.

If a flood certificate provides flood levels for existing conditions as

well as conditions in the year 2050 and 2100, climate change has

already been included when calculating the flood planning level.

Throughout the document various AEP flood events are referred to as well as the flood

planning level. It is up to the applicant to use the appropriate climate change conditions

for these AEP flood events and the flood planning level. For example, if the document

says “1% AEP flood event” this means the 2050 1% AEP flood event if the application is

for a new development or it means the 2100 1% AEP flood event if the application is for a

new subdivision.

6.5 Development application documents

Note: You cannot lodge a development application on flood prone

land without a flood DCP compliance report.

6.5.1 Flood Compliance Report

To enable Council to assess a development proposal, a flood DCP compliance report is to

be provided for every development proposal on flood prone land.

The flood DCP compliance report must include the following compulsory information:

Existing flood information on the site (prior to the proposed development)

The information can be provided as either:

a) A current flood certificate; or

b) A flood assessment report.

Note: Where available, an up to date flood certificate must be

submitted with your development application (refer Schedule 2 for

information on how to obtain this document and whether you need a

basic or detailed certificate)

A flood assessment report is needed in the following two instances:

1. Where flood data is not available but the site:

Is within 40 meters of a creek;

Is within 10 meters of a major drainage system, local



Page | 21

overland flood path or drainage easement; or

Has a history of flooding; or

Is considered to be flood prone by Council’s Floodplain

Engineer

OR

2. Where flood data is available but my require interpolation,

extrapolation, or refinement to greater detail.

Where a flood assessment report is required, the report must be

submitted with the development application as part of the flood DCP

compliance report.

A flood assessment report must be prepared by a suitable qualified

and experienced engineer recognised under the National

Professional Engineers Register (NPER) in this field. The full name

of the person who prepared the report, relevant qualifications and

registration number are to be provided on the front page of the

report.

Please refer to (Schedule 3 in this Chapter) for a detailed description

on what information is required within such a report.

Compliance

Assessment

A detailed assessment on how the proposed development will achieve all

relevant objectives, performance criteria and/or acceptable solutions of this

Chapter is required. It is expected that you list all relevant performance criteria

and explain how each individual criteria has been met.

Development

Plans

Plans for the proposed development or works that indicate compliance with all

relevant development controls must be submitted.

Survey Details

In addition to the requirement to lodge general survey details with the

development application, the survey plan prepared by a registered surveyor must

also indicate the following:

a) Existing ground levels at each corner of the proposed building envelope;

b) The floor levels of all existing buildings or structures to be retained as well

as proposed floor levels for all new buildings and structures; and

c) The location of any existing buildings or structures.

All levels must be relative to Australian Height Datum (AHD). Levels relating to an

arbitrary assumed datum are not acceptable.

Note: Some applications for minor / ancillary development may not

require survey details if a structural engineering certificate is

provided.

Fill or

Excavation

A development application that includes land filling must be supported by:

a) A site plan drawn to scale showing:



Page | 22

Details

i. The extent of the proposed filling or excavation and the existing

contours and levels of the land;

ii. The proposed contours and levels of the land and the depth and

quantity of the filling, and;

iii. Details of proposed filling material, the method of compaction and

stabilisation of the filling material.

b) Calculations showing the fill volume and the percentage of the 20%, 5%

and 1% AEP flood volume taken up by the proposed fill material on site

(for climate change conditions);

c) Details of the purpose of the proposed filling;

d) Details of the quality of the proposed fill material; and

e) Details of when the filling will be carried out and any other reasonable

information required by Council.

Note: Land filling means to place or allow to fall upon any land any

ballast, rock, stone, shingle, gravel, sand, clay, earth, cinders, debris

or any other matter or thing so as to alter the contours or levels of

the land.

6.5.2 Other additional development application documents

Note: The reporting requirements vary depending on the nature of the

proposed development. Please confirm with Council which certification

and reporting requirements apply to your specific development

application before commissioning a consultant to undertake the work.

Additional

Survey

Information

For some development the above minimum survey requirements may not be

sufficient to assess the proposed development. Council may ask for the following

additional information to be provided by the applicant:

a) Existing ground levels at 0.2 metre contour intervals across the entire

property (contours are to extend across adjoining land to enable suitable

consideration of the effect of the proposed development);

b) The ceiling heights of existing buildings or structures that are retained as well

as for proposed new buildings and structures;

c) Existing and/or proposed drainage lines (including sizes and if piped or open

channel) or easements and watercourses, or other means of conveying

stormwater that are relevant to the flood characteristics of the site; and,

d) The contour lines showing the 2050/2100 flood planning level and PMF level

if only parts of the property are flood prone.

Hydraulic

Impact

Assessment

Some development (see Schedule 6 Matrix) will require a hydraulic impact

assessment report. A hydraulic impact assessment report is a document prepared

by a suitably qualified hydraulic engineer, detailing how a proposed development will



Page | 23

Report

change flood behaviour on and off the site as well as how the new development

itself will be impacted by flooding.

Note: A suitably qualified hydraulic engineer means an experienced

and qualified professional engineer, recognised as a chartered

professional engineer by the Institution of Engineers Australia in the

field of civil engineering, flood risk management, emergency

management, structural engineering or similar, acting at all times within

their experience and qualifications, and able to demonstrate to Council

that they have the experience and qualifications to act as required.

The report must demonstrate that the development will not increase flood hazard or

flood damage to other properties or adversely affect flood behaviour for a 5% AEP

up to the PMF scenario (using the relevant 2050 or 2100 climate change conditions).

Note: The report must be prepared by a suitable qualified and

experienced civil engineer recognised under the National Professional

Engineers Register (NPER) in this field. The full name of the person

who prepared the report, relevant qualifications and registration

number are to be provided on the front page of the report.

Please refer to Schedule 3 for a detailed description on what information is required

within such a report.

Note: Hydraulics is a term given to the study of water flow in

waterways. In particular, the evaluation of flow parameters such as

water level and velocity.

Structural

Engineering

Certificate

Some developments may require structural engineering certification to ensure that

the proposed structures can withstand flood forces including debris and buoyancy

forces up to a specified flood scenario. Please refer to Schedule 4 to confirm the

level of certification required. Schedule 4 also provides suggested structural

conditions for developments affected by flood waters. Consultation with the Building

Code of Australia - Construction of Buildings in Flood Hazard Areas – Standard

2012 is also recommended.

Flood

Evacuation

Plan

Some development may require an engineering report demonstrating that

permanent, fail-safe, maintenance free measures are incorporated in the

development to ensure that the timely orderly and safe evacuation of people is

possible from the area and that it will not add significant cost and disruption to the

community or the SES.

Community

Consultation

Details

Some development may require a report on community consultation that was

undertaken as part of the pre-development investigations. It should note all issues

raised and how they were addressed.

Please note that Council may undertake further community consultation in

accordance with Council’s Community Consultation Policy for Subdivision and



Page | 24

Development Applications.

6.6 Flood DCP Compliance Report Checklist and Schedules

A flood DCP compliance report checklist is provided in this Chapter (Section 8), with

Schedules as identified thereafter.

7 Other legislation or policies you may need to check

Note: This section is not exclusive and you may be required to consider other legislation, policies and other documents with your application

Council Policies

& Guidelines

Engineering Guidelines

Floodplain risk management plans for specific areas

Community Consultation Policy for Subdivision and Development

Applications.

External Policies

& Guidelines

NSW Flood Prone Land Policy 1984

NSW Floodplain Development Manual 2005 and other associated

Guidelines

NSW Coastal Planning Guideline: Adapting to Sea Level Rise 2010

NSW Sea Level Rise Policy Statement 2009

Building Code of Australia - Construction of Buildings in Flood Hazard

Areas – Standard 2012.

Legislation Nil



Page | 25

8 Flood Compliance Report Checklist

Please check with Council’s Development Planner, which of the following items you need to provide with your development application.

Item Prepared by Required? Supplied

Current Flood Certificate or Flood Assessment Report

Compliance Assessment

Development Plans

Survey Details (Some applications for minor / ancillary development may not require full survey details if a structural engineering certificate is provided)

Fill or Excavation Details

Note: The items above are mandatory information required for a development application. The items below may be required depending on type and scale of the proposed development.

Additional Survey Details

Hydraulic Impact Assessment Report

Structural Engineering Certificate

Geotechnical Engineering Certificate

Flood Evacuation Plan

Community Consultation Details

Other:



Page | 26

Schedule 1 – Land Use Categories

The development purpose categories and land use types below are not exhaustive, but

indicative only. Where development does not fit within the categories, assessment

will be undertaken based on merit in accordance with the NSW Floodplain

Development Manual provisions. Council will determine, based on the documentation

provided to Council, which development purpose and land use category the proposal fits

into.

The development purpose categories are based on sensitivity to flood risk and are

different to terms used in planning legislation. The land use types listed are examples of

the possible land use within each development purpose category. Definitions of these land

use types are included in the Standard Instrument (Local Environmental Plans) Order

2006. They are not an exhaustive list and other activities such as stand alone drainage

applications should also comply with this DCP.

DEVELOPMENT PURPOSE

LAND USE TYPE

A(I) Single Residential/ Habitable Buildings

New Dwelling, Dwelling house, Exhibition home, Home business, Home industry, Home occupation, Rural worker’s dwelling and the like…

A(II) Other Residential/ Habitable Buildings

Attached dwelling, Bed and breakfast accommodation, Canal estate development, Dual occupancy, Exhibition village, Farm stay accommodation, Home-based child care, Hostel, Hotel or motel accommodation, Multi dwelling housing, Residential flat building, Secondary dwelling, Semi-detached dwelling, Serviced apartment, Shop top housing, Tourist and visitor accommodation and the like…

B Carpark Stand alone car park, ancillary car park and the like…

C Commercial/ Industrial/ Agricultural Buildings/ Retail

Agricultural produce industry, Agriculture, Airstrip, Amusement centre, Animal boarding or training establishment, Brothel, Bulky goods premises, Business Premises, Cellar door premises, Charter and tourism boating facility, Crematorium, Dairy (pasture-based), Depot, Entertainment facility, Environmental facility; Farm building, Food and drink premises, Freight transport facility, Function centre, Funeral chapel, Funeral home, Health consulting rooms, Heavy industry, Highway service centre, Industrial retail outlet, Industry; Information and education facility, Kiosk, Landscape and garden supplies, Light industry, Livestock processing industry, Marina, Markets, Medical centre, Mortuary, Neighbourhood shop, Nightclub, Office premises, Passenger transport facility, Place of public entertainment, Place of public worship, Pub, Public

http://www.legislation.nsw.gov.au/maintop/view/inforce/epi+155+2006+cd+0+N

http://www.legislation.nsw.gov.au/maintop/view/inforce/epi+155+2006+cd+0+N



Page | 27

administration building, Recreation facility, Registered club, Research station, Restaurant, Restricted dairy, Restriction facilities, Retail Premises, Rural industry, Sawmill or log processing works, Self-storage units, Sex service premises, Shop, Stock and sale yard, Storage premises, Take away food and drink premises, Timber and building supplies, Transport depot, Vehicle sales or hire premises, Veterinary hospital, Warehouse or distribution centre, and the like…

D Subdivision Residential subdivision, commercial subdivision and the like…

E Earthworks Extractive industry, Mining, Road, drainage works and the like…

F Resource Management/ Agriculture/ Recreational Activities

Aquaculture, Cemetery, Environmental Protection Works, Extensive agriculture, Feedlot, Forestry, Horticulture, Intensive livestock agriculture, Intensive plant agriculture, Natural water-based aquaculture, Open Space, Park, Pond-based aquaculture, Recreation area, Tank-based aquaculture, Turf farming.

G Critical Infrastructure Assets/ Potentially Polluting Activities

Air transport facility, Airport, Biosolids treatment facility; Electricity generating works, Hazardous industry, Hazardous storage establishment, Liquid fuel depot, Offensive industry; Offensive storage establishment; Public utility undertaking, Resource recovery facility, Service station, Sewage treatment plant, Sewerage system, Telecommunications facility, Waste disposal facility, Waste management facility, Waste or resource management facility, Waste or resource transfer station, Water recycling facility, Water reticulation system, Water storage facility, Water treatment facility.

H Buildings and activities requiring special evacuation consideration

Child care centre, Community facility, Educational establishment, Emergency services facility, Health services facility, Hospital, Residential care facility, Schools, Seniors housing.

I Minor Development Residential

A. Minor additions:

(i) Urban and rural residential dwelling:

A cumulative total of habitable additions (since 1988) to an existing dwelling of no more than 50m2 below the Flood planning level

or

A cumulative total floor area including all habitable and non-habitable areas on all storeys of the dwelling of 300 m2 (but with no more than a cumulative total habitable addition (since 1988) of 50m2 below the Flood planning level), whichever is the larger area;

(ii) Dwelling associated with a bona fide large rural



Page | 28

enterprise such as dairying:

No more than a cumulative total addition (since 1988) of 100 m2.

B. Minor alteration:

(i) Alterations to an existing dwelling comprising modifications to less than 40% of the internal and/or external walls (measured in linear metres) or 30 lineal metres whichever is the greater. Modifications shall include removal of existing walls and the installation of windows, doors or other openings.

Other Development

(i) A cumulative total addition below the flood planning level to the existing premises (since 1988) of not more than 10 % of the existing floor area.

Any development activities greater than those determined above shall be considered as major or new development.

Any extension to existing structures, that connect additional existing structures to the former with the result of one larger building, are considered as major or new development.

J Ancillary Structures Advertising structure, Boat launching ramp, Boat repair facility, Boat shed, Some Fences, Garage, Jetty, Mooring, Roadside stall, Signage; Temporary structure, Water recreation structure.

K Events i.e. music or art festival



Page | 29

Schedule 2 – Flood Information Enquiries and Flood Certificates

One component of your application is to determine whether the land proposed for

development is flood prone. To do this you can:

a) Look at Council’s online mapping by:

i. Searching Councils website www.shoalhaven.nsw.gov.au - the zoning details of properties within the Shoalhaven can be found in the LEP maps online. Where council has flood information, this is shown on the “flood planning area” Overlay. Alternatively you can look at the individual catchment maps in the flood risk section.

ii. Attending Councils Customer Service Counter in the Administration Building to view the mapping, or

iii. Contacting Council by either phone, email or in writing and request the flood information for a subject site.

OR

iv. Consult the Section 149 Planning Certificate (149 Certificate).

v. A 149 certificate for a parcel of land may state whether or not the land is subject to “flood related development controls”.

vi. Please note that land may still be flood prone even though the 149 Certificate contains no reference to flooding. Historical information is not contained in certificates and further research should be undertaken if the property is in the vicinity of a watercourse or if the contours suggest a local flowpath may cross the land. While existing flood information may not exist there is the possibility that a property is flood affected and further investigations by a suitably qualified engineer would be warranted.

vii. A 149 Certificate can be obtained by contacting Council.

If the property is flood affected you will need to obtain a Flood Certificate from Council. An

application fee applies in accordance with Councils Fees and Charges.

details the procedure for making a flood certificate request.

The Flood Certificate is required to be submitted with your development application.

Please note that there are two types of certificates available and you will need to specify

which type you are applying for:

A basic flood certificate will contain the following information (if available):

a) The 1% AEP flood level and the Flood planning level (including the relevant sea level rise component when available) for the individual property;

b) The hydraulic and hazard categorisation as per the NSW Floodplain Development Manual for the individual property; and

http://www.shoalhaven.nsw.gov.au/



Page | 30

c) The source of the provided data.

OR

A detailed flood certificate will include additional information such as PMF, 5% AEP, 20% AEP flood levels (including the relevant sea level rise component when available) and flood velocity. This information is generally required by structural engineers in order to provide hydraulic impact assessment reports for a development.

Note: In order to prevent misunderstandings and in accordance with Council policy, Public

Access to Council Information Policy, no verbal advice will be provided. Instead, you will

be referred to councils relevant LEP, any relevant Flood Study or Floodplain risk

management plan, or you may be requested to obtain a flood certificate.

Complete a flood certificate request in person from a customer service counter at Councils administration buildings or access the electronic form online via Council’s homepage: www.shoalhaven.nsw.gov.au

Enter all required information, property details and preferred mode of reply. Submit the completed form.

You will be sent an invoice; once the invoice has been paid your request will be completed by a flood engineer within 10 working days.

Figure 5: Procedure for obtaining a Flood Certificate from Council




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Schedule 3 – Technical Reporting Requirements

A - Flood Assessment Report A Flood Assessment Report must be prepared by a suitable qualified and experienced

engineer recognised under the National Professional Engineers Register (NPER) in this

field. The full name of the person who prepared the report, relevant qualifications and

registration number are to be provided on the front page of the report.

The assessment report provides information on existing flood risk for a catchment and is to

be commensurate with the NSW Floodplain Development Manual and must include the

following information:

(a) A description of the creek or drainage system that is relevant to the flood

characteristics of the site, whether located on, adjacent to or remote from the

development site;

(b) A plan showing cross-sections through site - as a guide, the following cross-section

information should be provided:

– A minimum of 5 cross-sections, at a maximum distance of 20m apart, should be

taken through the site, perpendicular to the likely flow path (i.e. the direction of

the cross-section may not necessarily be in a single straight line);

– One cross-section should be at the upstream end and one cross-section at the

downstream end of the proposed development site;

– Cross-sections should extend at least as high as the highest flood level

available at the site and if possible be wide enough to cover the full width of the

floodplain at that location; and

– The cross-sections should be plotted at a suitable exaggerated scale (i.e. the

vertical scale is not necessarily the same as the horizontal scale);

(c) Flood levels for the PMF, 1%, 5%, 10% and 20% AEP events for the climate change

pre development scenario (all assumptions, calculations and modelling output tables

must be provided);

(d) Flood velocities and vectors for the 1% AEP event for the climate change pre

development scenario (all assumptions, calculations and modelling output tables must

be provided);

(e) Provisional Hazard categories based on depth and velocity as well as obvious other

hazards such as evacuation difficulties as per the requirements of the 2005 NSW

Floodplain Development Manual;

(f) Provisional Hydraulic categories based on depth and velocity as per the requirements

of the 2005 NSW Floodplain Development Manual; and



Page | 32

(g) Plans showing the results of (c) to (f) as well as the location of the proposed

development.

Please note for:

dot point a) The modelling shall include climate change considerations as per

current Government Guidelines for both sea level rise and predicted changes in

rainfall.

dot point b) The modelling shall include a 50% and 100% blockage analysis of all

existing drainage structures that may affect the development site.

dot point c) Localised flow effects shall be investigated and reported on where

relevant.

dot point d) The roughness coefficients used shall allow for fully vegetated stream

conditions in order to account for potential revegetation of degraded areas without

impact on flood levels.

Note: Roughness coefficients describe the resistance of the bed of a channel to the

flow of water within it. They are used in equations calculating energy loss due to

roughness of a surface.

dot point e) In areas where local sub-catchment flooding, such as flows from

drains, overland flow paths or similar, interact with overall catchment flooding from

waterways and lakes; or, with ocean inundation a joint probability analysis of flood

behaviour shall be undertaken.

B - Hydraulic Impact Assessment Report For some development a Hydraulic Impact Assessment is required as part of the Flood

Management Report, demonstrating that the development will not increase flood hazard or

flood damage to other properties or adversely affect flood behaviour for a 5% AEP up to

the PMF scenario.

A Hydraulic Impact Assessment Report must be prepared by a suitable qualified and

experienced engineer recognised under the National Professional Engineers Register

(NPER) in this field. The full name of the person who prepared the report, relevant

qualifications and registration number are to be provided on the front page of the report.

This Schedule describes two methods for assessing hydraulic impacts of proposed

developments. The two methods are:

► Assessment Method 1 — Cross-section Analysis (No Computer Modelling);

► Assessment Method 2 — Use of Existing Flood Study data or Preparation of Site-

Specific Model (Computer Modelling).



Page | 33

Method 1 will be sufficient for small scale development proposals. For larger

developments, developments in sensitive areas, or where special circumstances exist,

Council may require assessment method 2 to be used.

Both Assessment Methods need to be carried out by an experienced engineer and are to

be commensurate with the NSW Floodplain Development Manual. In some

circumstances, Council may determine the method(s) to be used.

Assessment Method 1 - Cross-section Analysis (No Computer Modelling)

In order to satisfy the requirement that the development will not increase flood hazard or

potential flood damage to other properties or adversely affect flood behaviour for the full

range of flood scenarios, the applicant must demonstrate that:

(i) The proposed development will not involve fill volumes that occupy more

than 1% of the available 20%, 5% and 1% AEP flood volume on the

development site or involve cutting or filling in floodways.

Please note: it is too simplistic to assume that earthworks will have a

negligible impact on the hydraulics of a waterway if the net cut and fill

volumes for the PMF balance out. Hydraulic processes are complex and a

simple “total fill < total cut” equation will not guarantee that the flood storage

capacity of a waterway corridor are maintained. It is therefore necessary to

check net cut and fill volumes within the site over a range of flood events.

Note that ‘hydraulics’ is a term given to the study of water flow in waterways.

In particular, the evaluation of flow parameters such as water level and

velocity.

(ii) The proposed development will not adversely change flow direction and

velocity or create any new preferential flow paths for the PMF, 1%, 5%, 10%

and 20% AEP events; and

(iii) The proposed development will not change the flood conveyance at any of

the cross sections up to and including the PMF.

Please note:

Flood conveyance is a direct measure of the flow carrying capacity of a

particular cross-section of a stream or stormwater channel.

The flood conveyance should be calculated at each cross-section for pre-

development and post-development conditions. Flood conveyance should

be calculated at a range of water levels, at each cross-section, including the

1% AEP and PMF. All assumptions, particularly those relating to hydraulic



Page | 34

roughness, must be documented, especially where the development results

in a change in hydraulic roughness.

In special circumstances, small size developments inside a floodway may not

reduce conveyance (e.g. minor alterations or additions carried out in the ‘lee’

of an existing structure). In such cases, Council may require assessment

using Assessment Method 1 and 2 of this Schedule to demonstrate that

conveyance is not being reduced.

This method does not require computer modelling. It checks for changes in flood storage

volume, flood behaviour and conveyance at critical cross sections only through the

proposed development.

This approach, whilst simpler than computer modelling, assumes a thorough knowledge of

flood behaviour to ensure that the cross-section locations are representative of the

principal impacts of the development.

In addition to the survey details and pre development flood information, the following shall

be submitted, accompanied by appropriate supporting written information:

(a) Post development flood level plots for the PMF, 1%, 5%, 10% and 20% AEP events at

all cross sections (all assumptions, calculations and modelling output tables must be

provided);

(b) Post development in-stream and overbank flow velocity vector plots for the 1% AEP

event at all cross sections (all assumptions, calculations and modelling output tables

must be provided);

(c) Calculation results for all calculations undertaken in order to demonstrate the above

requirements; and

(d) Pre and post development ground surface levels — this information should be shown

on each cross-section, with areas of cut and fill clearly shown.

Assessment Method 2 - Use of Existing Flood Study or Preparation of Site-Specific Flood

Study (Computer Modelling)

This method requires computer modelling. An existing flood study model may be used if

available and suitable (e.g. it contains sufficient local detail).

For large scale developments or developments in critical locations, a flood study using a

fully dynamic one or two dimensional hydraulic computer model may be required. Such a

flood study would be prepared in a manner consistent with the NSW Floodplain

Development Manual, Australian Rainfall and Runoff — A Guide to Flood Estimation

(Institution of Engineers, Australia, 1987) and relevant Council codes.



Page | 35

In addition to the survey details and pre development flood information, the following shall

be submitted in plan form, accompanied by appropriate supporting written information:

(a) Post development water surface contours — these should be provided in metres to

Australian Height Datum (m AHD);

(b) Post development flood profiles — these should be provided at a suitable vertical and

horizontal scale such that any changes in flood levels are easily identified;

(c) Post development velocity vectors — these show direction and relative size of flood

velocities and should be provided in metres per second (m/s);

(d) Difference plots for flood levels and velocities for the 20% and 1% AEP flood events;

(e) Post development contours of flood velocities multiplied by depth of flooding over

ground level indicating provisional hydraulic categories as per the requirements of the

2005 NSW Floodplain development manual — these should be provided to one

decimal place; and

(f) Post development provisional hazard categories based on depth and velocity as well

as obvious other hazards such as evacuation difficulties as per the requirements of the

2005 NSW Floodplain development manual.

An interpretation of the results clearly indicating the effects of the proposed development

on general and local flood behaviours and potential impacts on neighbouring properties is

to be provided. This interpretation should clearly inform the last section of the Flood DCP

Compliance Report which seeks to provide a detailed assessment of how the proposed

development will achieve the objectives and performance criteria of this DCP.

Please note:

A range of flood sizes should be chosen for the above analyses so that the full

impacts of the development can be assessed. Typically, the flood sizes to be

considered would be: a 20% AEP, 5% AEP, 1% AEP and a probable maximum

flood.

For the post-development scenario, all proposed works and structures, including

any revegetation and enhancements should be included in the analysis.

All assumptions relating to hydraulic roughness should be clearly documented.

Flood levels and velocities need to be computed not only at the site but also at an

appropriate distance upstream and downstream to allow the principal impacts of the

development to be determined.



Page | 36

C - Structural Conditions for Developments Affected by Flood A structural engineer should certify that the building will be able to withstand hydrostatic

and hydrodynamic forces of flood waters including debris and buoyancy forces based on

relevant depth, velocity and debris loadings for the specific site.

Some guidance is provided in Appendix A of the Hawkesbury and Nepean floodplain

Management Steering committees. Reducing Vulnerability of Buildings to Flood Damage.



Page | 37

Schedule 4 – Flood Proofing Guidelines

There are many different ways in which to reduce flood damages and flood proofing is

generally recommended for any building on land that is considered by Council as being

flood prone. Flood proofing refers to the design and construction of buildings with

appropriate water resistant materials such that flood damage to the building is minimised,

should it be inundated. Certain types of materials are better able to withstand inundation

than others, for example, plasterboard and chipboard, both materials commonly used for

the internal wall linings and cupboard fittings of a house, can be badly damaged on

inundation and may have to be replaced. In contrast, double brick construction can

withstand inundation and may only require a hose and scrub down when the flood

subsides.

Adequate flood proofing of buildings in flood liable areas is an effective and equitable

means of reducing flood damage to the structure or building. The following table provides

information on flood proofing measures and flood compatible materials (being those

materials used in building that are resistant to damage when inundated). The table is not

an exhaustive list, however provides an indication of what is considered as suitable in

flood prone areas.

Further reference can be made to the Building Code of Australia - Construction of

Buildings in Flood Hazard Areas – Standard 2012

A) Construction Methods and Materials

Construction methods and materials listed in the following table are graded into four

classes according to their resistance to floodwaters:

Suitable - the materials or products which are relatively unaffected by submersion and

unmitigated flood exposure and are the best available for the particular application.

Mild effects - where the most suitable materials or products are unavailable or economic

considerations prohibit their use, these materials or products are considered the next best

choice to minimise the damage caused by flooding.

Marked effects - as for "2nd preference" but considered to be more liable to damage

under flood conditions.

Severe effects - the materials or products listed here are seriously affected by floodwaters

and in general have to be replaced if submerged. They are not recommended for use in

flood prone areas.



COMPONENT

SUITABILITY OF MATERIAL OR CONSTRUCTION METHOD

Suitable Mild Effects Marked Effects Severe Effects

Floor & Sub-Floor

Structure

concrete slab-on-ground monolith construction where the ground level allows the Flood planning level requirements to be met

note: clay filling is not permitted beneath slab-on-ground construction, which could be inundated

suspension reinforced concrete slab

timber floor (T&G boarding, marine plywood) full epoxy sealed joints

timber floor (T&G boarding, marine plywood) with ends only epoxy sealed on joints and provision of side clearance for board swelling

timber close to ground surrounding base

timber flooring with ceilings or soffit linings

timber flooring with seal on top only

Floor Coverings clay tiles

concrete, precast or in situ

concrete tiles

epoxy, formed-in-place

mastic flooring, formed-in-place

rubber sheets or tiles with chemical-set adhesives

silicone floors formed-in-place

vinyl sheets or tiles with chemical set adhesives

ceramic tiles, fixed with mortar or chemical set adhesive

cement / bituminous formed-in-place

cement / latex formed-in-place

rubber tiles, with chemical set adhesive

terrazzo

vinyl tile with chemical-set adhesive

vinyl-asbestos tiles asphaltic adhesives

loose rugs

ceramic tiles with acid and alkali-resistant grout

asphalt tiles with asphaltic adhesives

loose fit nylon or acrylic carpet with closed cell rubber underlay

carpeting, glue-down type or fixed with smooth edge on jute felts

chipboard (particle board)

cork

linoleum

PVA emulsion cements

vinyl sheets or tiles coated on cork or wood backings

fibre matting (sea- grass matting)



Page | 39

COMPONENT SUITABILITY OF MATERIAL OR CONSTRUCTION METHOD

asphalt tiles, fixed with water resistant adhesive

Wall Structure (up

to FPL)

solid brickwork, block-

work, reinforced,

concrete or mass

concrete

two skins of brickwork or

block-work with inspection

openings

brick or block-work veneer

construction with inspection

openings

inaccessible cavities

large window openings

Roof Structure (for

situations where

FPL is above the

ceiling of an

existing building)

reinforced concrete

construction

galvanised metal

construction

timber trusses with

galvanised fittings

traditional timber roof

construction

inaccessible flat roof

construction

ungalvanised steelwork eg.

lintels, arch bars, tie rods,

beams, etc.

unsecured roof tiles

Doors (below FPL) solid panel with water

proof adhesives

flush door with marine

ply filled with closed cell

foam

painted metal

construction

aluminium or galvanised

steel frame

flush panel or single panel

with marine plywood and

water proof adhesive

T&G lines door, framed

ledged and braced

painted steel

timber frame fully epoxy

sealed before assembly

fly-wire doors

standard timber frame

hollow core ply with PVA

adhesives and honeycomb

paper core

Wall & Ceiling

Linings (up to the

FPL)

cement board

brick, face or glazed

clay tile glazed in

waterproof mortar

brick, common

plastic wall tiles

metals, non ferrous

chipboard exterior grade

hardboard exterior grade

wood, solid (boards or

timber) with allowance for

chipboard

fibreboard panels

mineral fibreboard



Page | 40

COMPONENT SUITABILITY OF MATERIAL OR CONSTRUCTION METHOD

concrete

concrete block

steel and waterproof

applications

stone, natural solid or

veneer, waterproof

ground

glass blocks

glass

plastic sheeting or wall

with waterproof adhesive

rubber mouldings and trim

wood, solid or exterior

grade plywood fully sealed

swelling

wood, plywood exterior

grade

fibrous plaster board

paperboard

plaster-board, gypsum plaster

wall coverings (paper, burlap

cloth types)

wood, standard plywood

strawboard

Insulation (up to

FPL)

foam or closed cell types reflective insulation bat or blanket types open cell fibre types

Windows (below

FPL)

aluminium frame with

stainless steel or brass

rollers or similar

corrosion and water

resistant material

epoxy sealed timber

waterproof glues with

stainless steel or brass

fittings

galvanised or painted steel

timber with PVA glues mild

steel fittings

Nails, Bolts,

Hinges & Fittings

(below FPL)

brass, nylon or stainless

steel

removable pin hinges

hot dipped galvanised steel

wire nails

aluminium

mild steel

More information on reducing vulnerability of buildings from flood damage please refer to Reducing Vulnerability of Buildings to Flood Information prepared by the Hawkesbury-Nepean Floodplain Management Steering Committee



Page | 41

B) Electrical and Mechanical Equipment

For dwellings constructed on flood liable land, the electrical and mechanical

materials, equipment and installation must conform to the following requirements:

Main power supply - Subject to the approval of the relevant power authority, the

incoming main commercial power service equipment, including all metering

equipment, is to be located above the flood planning level. Means are to be

available to easily disconnect the dwelling from the main power supply.

Wiring - all wiring, power outlets, switches, etc., must, to the maximum extent

possible, be located above the flood planning level. All electrical wiring installed

below the flood planning level must be suitable for continuous submergence in water

and must contain no fibrous components. Only submersible-type splices are to be

used below the Flood planning level. All conduits located below the flood planning

level are to be so installed that they will be self-draining if subjected to flooding.

Equipment - All equipment installed below or partially below the flood planning level

must be capable of disconnection by a single plug and socket assembly.

Reconnection - Should any electrical device and/or part of the wiring be flooded it

must be thoroughly cleaned or replaced and checked by an approved electrical

contractor before reconnection.

C) Heating and Air Conditioning Systems

Heating and air conditioning systems must, to the maximum extent possible, be

installed in areas and space of the house above the Flood planning level. When this

is not feasible every precaution must be taken to minimise the damage caused by

submersion according to the following guidelines:

Fuel - Heating systems using gas or oil as a fuel must have a manually operated

valve located in the fuel supply line to enable fuel cut-off.

Installation - The heating equipment and fuel storage tanks must be mounted on

and securely anchored to a foundation pad of sufficient mass to overcome buoyancy

and prevent movement that could damage the fuel supply line. All storage tanks

must be vented to an elevation of 0.5m above the Flood planning level.

Ducting - All ductwork located below the Flood planning level must be provided with

openings for drainage and cleaning. Self draining may be achieved by constructing

the ductwork on a suitable grade. Where ductwork must pass through a water-tight

wall or floor below the Flood planning level, the ductwork must be protected by a

closure assembly operated from above Flood planning level.



Page | 42

Schedule 5 – Flood Related Development Controls – Site Specific as per the adopted Floodplain Risk Management Plan

This schedule provides site specific flood related development controls as recommended by Council adopted Floodplain Risk Management Plans (FRMP) that have been prepared for individual catchments consistent with the NSW Floodplain Development Manual. Information for specific areas will be added as Floodplain Risk Management Plans are completed. Note: Where the site specific controls are in conflict with the generic

flood related controls in Section 14 – Schedule 6, the site specific controls will override the generic ones.



Page | 43

A - Terara Village Floodplain Risk Management Plan (Adopted in 2002)

Area to which this plan applies:

For a map of the area to which this plan applies, please view Council’s maps on


Site specific flood characteristics:

Land within Terara Village becomes a high hazard floodway in a 1% AEP flood

event. Due to the initial protection against direct river flooding from the levee, it is

likely that the community will not be prepared for the sudden change in flood hazard

which may occur with levee overtopping or failure.

Site specific flood related development controls:

Location /

Type of

Development

Specific Controls

All of Terara

Village FRMP

study area

Vacant lots cannot be developed for residential buildings unless Council is

satisfied that the dwelling house is essential for the proper and efficient use of

the land for agriculture or turf farming.

Development in a high hazard floodway will only be permitted if it can be

shown that there is no other viable alternative. Further considerations would

then need to be made regarding the specific location of the development.

The minimum required floor level for infill development and reconstruction in

the Terara village area is the 1 in 100 year pre levee flood level plus a

freeboard of 0.5 m for habitable rooms.

New

residential

buildings

where

approved in

conjunction

with

agricultural

use

Structural soundness of completed works to withstand water and debris

damage up to the 0.2% AEP (1 in 500 year) event is to be certified by a

suitably qualified structural engineer.

Owners must have measures in place to enable them to self evacuate so as to

not place additional burden on Emergency Services




Page | 44

B - Riverview Road Area Floodplain Risk Management Plan: (Adopted in 2002) Area to which this plan applies:




Land within the Riverview Road Area is currently protected to the 1% AEP level from

direct inundation from the Shoalhaven River by the Riverview Road levee. However,

buildings will be inundated from backwater flooding across Ferry Lane. During larger

events, the area becomes a high hazard floodway and it is likely that the community

will not be prepared for the sudden change in hazard which may occur with levee

overtopping or failure.


Location /

Type of

Development

Specific Controls

All of Riverview Road

Area FRMP Study

Area

No new subdivision approvals will be granted as it would increase the

demand on the rescue services and the risk to life.

The minimum required floor level for infill development and reconstruction

is the 1 in 100 year pre levee flood level plus a freeboard of 0.5m for

habitable rooms.

New residential

buildings where

approved in

accordance with the

zoning requirements

Structural soundness of completed works to withstand water and debris

damage up to the 0.2% AEP (1 in 500 year) event is to be certified by a

suitably qualified structural engineer.

Owners must have measures in place to enable them to self evacuate to

not place additional burden on Emergency Services

New residential

buildings within:

– Riverview Road,

– Elia Avenue

– Lyrebird Drive subdivision

Lot 7 DP809132

Lot 1 DP1053438

Lot 2 DP1053438

Lot 6 DP538956

Lot 1 DP449102

All vacant land within IDO No.1 not already subdivided.

No Dual Occupancies or subdivisions will be permitted




Page | 45

C - St Georges Basin Floodplain Risk Management Plan: (Adopted 24th October 2006)





The majority of the properties affected in the 1% AEP event are associated with the

canal estates and other areas accessed by Jacob Drive at Sussex Inlet. The flood

hazard in this area has been classified as high and there is little which can be done

to mitigate the risks for the existing situation.


Location /

Type of Development Specific Controls

St Georges Basin and tributary

creeks foreshore areas

A minimum setback of 40m from Normal Water Level

shall apply for new development (Please check Water

Management Act and Estuary Management Plans for

most up to date setback requirement).

The Nebraska Estate Only minimal increase in development and population

will be permitted in this area.

Loralyn Avenue properties

An additional freeboard of 0.3m on top of the Flood

planning level is to be enforced to new development to

account for wind wave conditions.

Lot 1 DP 1120892 - 9 Fisherman Rd

Home Creek

Lot 89 DP 247696 - 41 Roulstone

Crescent Sanctuary Point

Lot 23 DP 7984 - 20 Kallaroo Rd

Erowal Bay

Lot 5 DP 21261 – 5 Wunda Ave

Sussex Inlet

Lot 9 DP 21261 - 13 Wunda Ave

Sussex Inlet

Lot 143 DP 21038 - 52 Ellmoos Ave

Sussex Inlet

House raising by 3m (one floor) should be explored as

part of any new development application for these

properties.

Services infrastructure and utilities,

sports field amenities or similar in

high hazard floodway areas

These will only be permitted if it can be shown that

there is no other viable alternative. A merit based

assessment is to be undertaken and if approved,

conditions to minimise risk to life, property and the

environment will be imposed.




D - Lower Shoalhaven River Floodplain Risk Management Plan: (Adopted in 2007)





The areas most affected by high hazard flood conditions include the main Shoalhaven

River channel from Nowra to the entrance, the Crookhaven River from Culburra Road to

the entrance, Berry’s Canal and the land to the east including the low areas of Comerong

Island and the residential area of Greenwell Point from Greens Road in the west and

South Street in the north through to the waterway as well as Hay Avenue in Shoalhaven

Heads. Remaining areas within the Lower Shoalhaven River floodplain are classified as

high hazard storage areas to low hazard flood fringe.


Location /

Type of

Development

Specific Controls

Hay Avenue.

Shoalhaven Heads

Although not a control, the area falls under high hazard floodway zone and is

currently deferred from the 1985 Local Environmental plan and is

administered under IDO (Interim Development Order) No. 1. Further

development would increase the permanent population to a high hazard

floodway area. Consequently, if the development were to be approved then

there would be increased reliance on rescue services during flood

emergencies. Resolution of an appropriate zoning and development controls

for this area needs to be addressed through an LEP amendment.

Greenwell Point

Any further expansion or new development beyond the current residential

zoning will not be permitted.

No subdivision, dual occupancy or strata development even on flood free

land will be permitted.

Industrial

Development at

Bomaderry

The potential hydraulic effects of any future construction works shall be

minimised through locating them in the “shadow” of other buildings or away

from the main flow paths where possible.

Any proposed works must be designed and located to minimise any increase

in flood damages to other users/occupiers of the floodplain.

A full hydraulic assessment will be required prior to any future development

or redevelopment to assess the potential impacts upon flooding.




Page | 47

Bomaderry

22, 64 Bolong

Road

House raising by 3m (one floor) should be explored as part of any new

development application for these properties.

Culburra Beach /

Orient Point

3 Raglan Street

41 Prince Edward

Avenue

House raising by 3m (one floor) should be explored as part of any new

development application for these properties.

All Lower

Shoalhaven

Foreshore areas

A minimum setback should be applied to all new development on the

foreshore and tributary creeks of the Shoalhaven and Crookhaven Rivers

which is consistent with the Water Management Act 2000 (previously Rivers

and Foreshores Improvement Act 1948) which specifies the requirement of a

permit for development within 40 meters of the top of bank or shoreline.

Flood Mitigation

Drains

Inappropriate enlargement of flood mitigation drains may cause removal of

natural wetlands and cause exposure of acid sulphate soils. Local landowner

modifications to the existing mitigation drains will require Council’s written

approval.



Page | 48

E - Burrill Lake Floodplain Risk Management Study and Plan (Adopted 26 March 2013)

Location /

Type of

Development

Specific Controls

High Hazard areas No intensification of development - no dual occupancies or sub-divisions to

be permitted in high hazard flood zones which would increase potential risk

to life and demands on emergency services.

All areas within

2050 flood

planning area

No filling – a moratorium on filling is proposed until a long term climate

change adaptation strategy is established.

All new

development

Emergency plans - a flood emergency response and evacuation plan to be

mandatory for all new development. Such plans would be required to

demonstrate understanding of flood warning, emergency response

procedures, effective evacuation routes and post-flood recovery

considerations.



Page | 49

F - Conjola Lake Floodplain Risk Management Study and Plan (Adopted 26 March 2013)

Location /

Type of

Development

Specific Controls




All areas within

2050 flood

planning area



All new

development





considerations.



Page | 50

G - Broughton Creek Floodplain Risk Management Study and Plan (Adopted 2013)

Location /

Type of

Development

Specific Controls




All areas within

2050 flood

planning area



All new

development





considerations.



Schedule 6 – Flood Related Development Controls - Generic

Risk Category

Sin

gle

Resid

ential /

Habitable

Build

ings

Sin

gle

Resid

ential /

Habitable

Build

ings

Exis

ting U

se R

ights

Only

!

Oth

er

Resid

ential /

Habitable

Build

ings

Carp

ark

s

Com

merc

ial/ I

ndustr

ial/A

gricultura

l

Build

ings/R

eta

il

Exis

ting U

se R

ights

Only

!

Com

merc

ial/ I

ndustr

ial/A

gricultura

l

Build

ings/R

eta

il

Subdiv

isio

n

Eart

hw

ork

s

Resourc

es M

anagem

ent/

Agriculture

/

Recre

ational A

ctivitie

s

Critical In

frastr

uctu

re A

ssets

/ P

ote

ntially

Pollu

ting A

ctivitie

s

Build

ings a

nd a

ctivitie

s r

equirin

g s

pecia

l

evacuation c

onsid

era

tion

Min

or

Develo

pm

ent

Ancill

ary

Str

uctu

res

Sin

gle

Resid

ential /

Habitable

Build

ings

Oth

er

Resid

ential /

Habitable

Build

ings

Carp

ark

s

Com

merc

ial/ I

ndustr

ial/A

gricultura

l

Build

ings/R

eta

il

Subdiv

isio

n

Eart

hw

ork

s

Resourc

es M

anagem

ent/

Agriculture

/

Recre

ational A

ctivitie

s

Critical In

frastr

uctu

re A

ssets

/ P

ote

ntially

Pollu

ting A

ctivitie

s

Build

ings a

nd a

ctivitie

s r

equirin

g s

pecia

l

evacuation c

onsid

era

tion

Min

or

Develo

pm

ent

Ancill

ary

Str

uctu

res

A(I

)

A(I

)*

A(I

I)

B

B(I

)*

C D E F G H I J

A(I

)

A(I

I)

B C D E F G H I J

FLOOR LEVEL 1 1 1 or 4** 1 1 5 1 3 1 or 4**

BUILDING COMPONENTS 1, 2 1, 2 1, 2 1, 2 1, 2 1, 2 1, 2 1, 2 1, 2 1, 2 1,2 1, 2 1, 2

STRUCTURAL SOUNDNESS 2, 4 2, 4 3 2 3 2, 4 2, 4 2, 4 2, 4 3 2,3,4 2 3

Hydraulic Impact 1 1 1,2 1 1 1 2 1 2 1,2 1,2 1

ACCESS 1,2 1,2 3 1,2 1,2 1,2 1,2 1 3

FLOOD EVACUATION PLAN 1 1 1 1 1 1 1 1

MANAGEMENT & DESIGN 1, 3 1,2,3 1,2 1 1,3 1,3 1,3 1,2,3 1,2,3 1

Not suitable for development

Not required

Note: For definitions of Land Use Categories refer to Schedule 2

* This type of development is not suitable within the risk category - ** Control No. 1 is desirable however

however, if existing use rights can be established and there is no other option, if this cannot be achieved Control No. 4 is acceptable

the conditions as per the matrix will apply

La

nd

Us

e C

ate

go

ry

(As

pe

r s

ch

ed

ule

2)

High Hazard Floodway High Hazard Flood Storage or Flood Fringe



Page | 52

Sin

gle

Resid

ential /

Habitable

Build

ings

Oth

er

Resid

ential /

Habitable

Build

ings

Carp

ark

s

Com

merc

ial/ I

ndustr

ial/A

gricultura

l

Build

ings/R

eta

il

Subdiv

isio

n

Eart

hw

ork

s

Resourc

es M

anagem

ent/

Agriculture

/

Recre

ational A

ctivitie

s

Critical In

frastr

uctu

re A

ssets

/ P

ote

ntially

Pollu

ting A

ctivitie

s

Build

ings a

nd a

ctivitie

s r

equirin

g s

pecia

l

evacuation c

onsid

era

tion

Min

or

Develo

pm

ent

Ancill

ary

Str

uctu

res

Sin

gle

Resid

ential /

Habitable

Build

ings

Oth

er

Resid

ential /

Habitable

Build

ings

Ca

rpa

rks

Com

merc

ial/ I

ndustr

ial/A

gricultura

l

Build

ings/R

eta

il

Subdiv

isio

n

Eart

hw

ork

s

Resourc

es M

anagem

ent/

Agriculture

/

Recre

ational A

ctivitie

s

Critical In

frastr

uctu

re A

ssets

/ P

ote

ntially

Pollu

ting A

ctivitie

s

Build

ings a

nd a

ctivitie

s r

equirin

g s

pecia

l

evacuation c

onsid

era

tion

Min

or

Develo

pm

ent

Ancill

ary

Str

uctu

res

A(I

)

A(I

I)

B C D E F G H I J

A(I

)

A(I

I)

B C D E F G H I J

FLOOR LEVEL 1 1 5 1 3 4 1 1 3 2

BUILDING COMPONENTS 1,2 1, 2 1, 2 1, 2 1, 2 1,2 1, 2 1 1 1,2 1

STRUCTURAL SOUNDNESS 4 4 3 4 4 1

Hydraulic Impact 2 1,2

ACCESS 1,2 1,2 1,2 1,2 1,2 3 1

FLOOD EVACUATION PLAN 1 1

MANAGEMENT & DESIGN 1,2,3 1,2,3

Not suitable for development

Not required

For definitions of Land Use Categories refer to Schedule 2

This type of development is not suitable within the risk category -

however, if existing use rights can be established and there is no other option,

the conditions as per the matrix will apply

Outside Flood Planning Area(Above the Flood Planning Level but below the PMF)

La

nd

Us

e C

ate

go

ry

(As

pe

r s

ch

ed

ule

2)

Low Hazard Floodway or Flood Storage or Flood Fringe

Figure 1 : Matrix to Determine Flood Related Development Controls continued



Development Controls Matrix Legend

Floor Level:

1. 1% AEP flood level + 0.50M freeboard;

2. Probable maximum flood level;

3. 5% AEP flood level;

4. Existing habitable floor level or higher as practical; and

5. High enough to ensure a velocity - depth product of less than 0.3 m2/s for a 1% AEP flood event.

Building Components:

1. Any portion of the building or structure below the FPL to be built from flood compatible materials

(being those materials used in building that are resistant to damage when inundated); and

2. All electrical installations to be above the FPL.

Structural Soundness:

1. Appropriate consulting engineer’s report – the building can withstand forces of floodwaters including

debris and buoyancy forces up to the PMF scenario;


debris and buoyancy forces up to the 0.2% AEP flooding scenario;


debris and buoyancy forces up to a 1% AEP flooding scenario;

4. Appropriate consulting engineer’s report – the structure will not become floating debris during a 1%

AEP flooding scenario; and

5. Certification of building foundations by a chartered geotechnical practitioner.

Hydraulic Impact:

1. Appropriate consulting engineer’s report for building footprint areas over 250 square metres, a

footprint length of more than 20 metres or any development that in the view of Council has the

potential to significantly impact on others. The report is to prove that the development will not

increase flood hazard or flood damage to other properties or adversely affect flood behaviour for a

5% AEP up to the PMF scenario.

No hydraulic impact report is required if the proposed building is raised on piers allowing free flood

flow for a 1% AEP flood event.

2. Appropriate consulting engineers report for earthworks of volumes exceeding 250 cubic metres or

with a length of more than 20 metres. The report is to prove that the earthworks will not increase

flood hazard, flood damage or adversely affect other properties for a 5% AEP up to the PMF

scenario.

Access:

1. Reliable emergency vehicle access is required for ambulance, SES, fire brigade, police and other

emergency services during a 1% AEP flood event;

2. Reliable access for pedestrians is required during a 1% AEP flood event; and

3. Reliable access for pedestrians is desirable during a 1% AEP flood event.

Note: Reliable access means the ability for people to safely evacuate an area subject to imminent flooding

within effective warning time having regard to the depth and velocity of floodwaters, the suitability of the

evacuation route, and without the need to travel through areas where the “water depth - velocity product” is

greater than 0.3m2/s. Effective warning time is the time available after receiving advice of an impending flood

and before the floodwaters prevent appropriate flood response actions being undertaken.



Page | 54

Flood evacuation plan:

1. Appropriate engineers report demonstrating that permanent, fail-safe, maintenance-free measures

are incorporated in the development to ensure that the timely, orderly and safe evacuation of people

is possible from the area and that it will not add significant cost and disruption to the community or

the SES.

Management and design:

1. Applicant to demonstrate that there is an area where hazardous and valuable goods can be stored

above the 1% AEP Flood Level;

2. Bunding to the FPL to be installed around hazardous chemical storage areas or the like; and

Applicant to demonstrate that there is an area where animals can find refuge above the 1% AEP Flood Level

Documents

CHAPTER G9: DEVELOPMENT ON FLOOD PRONE LANDdcp2014.shoalhaven.nsw.gov.au/sites/dcp2014.shoalhaven.nsw.gov.au... · Chapter G9: Development on Flood Prone Land Table of Changes