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Wollongong City Council

Flooding, Stormwater and Development

Flooding

If your land is prone to flooding, you will need to make sure any new development is done in a way to minimise the risk of floods to life and property.

Chapter E13 of our Development Control Plan PDF, 7598.16 KB explains how development needs to consider risks posed by flooding. Our development controls are based on the NSW Government's Flood Prone Land Policy, and the NSW Government Floodplain Development Manual 2015.

The specific planning rules that apply to your property will depend on how the land will be used, where it's located, and any relevant information Council has about flooding in your area.

Council staff can also give you general development advice and confirm what information, applications and approvals will be needed.

Council has flood information for many properties across our city. This includes information about past and / or anticipated flood levels, and flood risk precincts.

There are to main ways you can get information from Council about how flooding affects your property.

  1. Apply for flood level information. This includes details about past and expected flood levels. We don't have flood level information for all properties, so you should call us on (02) 4227 7111 to check if information is available before you start an application.
  2. Apply for a Planning Certificate. You'll need to request a combined 10.7(2) and 10.7(5) planning certificate to get information about whether the property is flood affected, and the flood risk category if available.

Links to both of these applications can be found on our Property Information page.

You can also our Catchment pages for information about past and current flood studies across our city.

You can view potentially flood-affected areas on our online planning map.

Look for the 'Layers' menu on the map. Under the 'Constraints and Planning DCPs' field, tick 'Flood Information'. You may need to zoom in or out to see the flood area information.

Note that these maps provide a general guide only. You should apply for flood information if you need to confirm details for a development.

Flood information can be complicated. You should consult a qualified civil engineer with experience in hydraulics and floodplain management for advice about how flood information will affect your development.

You will also need to get a detailed ground level survey of your property from an independent registered surveyor. The results of this survey can be compared with the flood information from Council to determine the potential depth and extent of flooding on your property.

Information provided by Council

If flood information is available for your property, you will generally get up to four main types of information from Council. Note that some or all of these types of information may not be available for all properties:

  1. Historical recorded flood levels
  2. Flood level information, including
    1. Existing flood levels for 20% AEP (annual exceedance probability), 1% AEP and PMF (probable maximum flood) levels.
    2. Climate change flood levels
  3. Flood risk precinct details if applicable
  4. Other relevant information. This could include details of our flood studies, or any other available information.

Australian Height Datum

We provide flood level information relative to Australian Height Datum (AHD).

All flood levels, floor levels and ground levels are provided in metres AHD. This is the elevation (on the ground) of any object relative to sea level, which is 0 metres AHD.

In most cases you should be able to develop a flood affected property as long as you follow planning requirements to manage flood risk.

Chapter E13 of our Development Control Plan PDF, 7598.16 KB explains the local flood-related planning controls.

Our Development Control Plan refers to the 1 in 100-year flood level, the Probable Maximum Flood (PMF) level, and the flood risk precincts. You will need to get this information for your property when you prepare a development application. See the 'How to get flood information' section of this page for details.

Advice about the development potential of flood affected property

You should get advice from a suitably qualified consultant engineer with experience in hydraulics and floodplain management to confirm what development could potentially be done on a property. They will generally need the following information before they can provide you with advice:

Council does not have flood information for every property in Wollongong.

If your property is not covered by our Flood Risk Precinct maps, or if it is 'uncategorised', you will need to get advice from a suitably qualified consulting civil engineer.

You may need to get a flood study done as part of your development application if your property is in the floodplain and:

  • It's likely your development will cause a flooding impact on surrounding properties.
  • The development is in an area where Council does not have an adopted flood study. You can find adopted flood studies on our Catchment pages.

Contact us for Development Advice to confirm if you'll need to get a flood study before you submit a development application.

The minimum habitable floor level for most development needs to be at the 1 in 100-year flood level, plus 0.5 metres freeboard. This is known as the flood planning level.

For more details, and other flood-related planning requirements, see Chapter E13 of our Development Control Plan PDF, 7598.16 KB.

Stormwater

Managing stormwater is an important part of development, and plays a significant role in reducing the impact of flooding.

Requirements for managing stormwater can be found in Chapter E14 of our Development Control Plan PDF, 5497.53 KB.

Stormwater from a single dwelling can usually be disposed of by piping to the street kerb and gutter, Council's underground drainage system, a drainage easement, or an absorption system.

See Chapter E14 of our Development Control Plan PDF, 5497.53 KB and our Domestic Stormwater Drainage Systems page for more information.

Before you can connect your stormwater to the kerb and gutter, you'll need a permit from Council to excavate the footpath and road reserve. Use the form below to apply.

Application for Works in Road Reserve PDF, 72.33 KB.

View fees and charges for application for works on roads and footpaths.

Council does not keep records or diagrams of private stormwater systems.

We only have stormwater diagrams for the stormwater networks that Council maintains. These can be provided on request for a fee. Call us on (02) 4227 7111 for more information.

Sydney Water also provides sewer diagrams and prints that may help you identify service locations, sewers and supply systems.

An easement is a nominated section of public or private land that is used by someone other than the land owner to access drainage, sewer, water, gas, electricity or similar services.

Drainage easements

If you're proposing a new development on a property that slopes downhill away from the road, you will need to obtain a drainage easement. Drainage easements must be 1 metre wide, angled downhill towards a natural watercourse or Council drainage system. This is so water will keep draining in the same direction as it currently does after your development is in place.

It is the responsibility of the developer to handle any negotiations with other property owners to secure an easement before Council will approve a proposed development.

Building or developing over easements

When an easement is created, major development or construction will usually not be allowed on that part of the land.

Council may consider proposals for very light buildings like open carports or other open structures on easements. This is assessed case-by-case, and often strict conditions will be placed on any approved work.

Building next to a drainage easement is allowed as long as the proposed development meets the requirements of Chapter E14 of our Development Control Plan PDF, 5497.53 KB.

An on-site stormwater detention (OSD) temporarily stores stormwater runoff, and reduces the rate of runoff flowing onto other properties or into Council's drainage system. This is important to help control the movement of water and reduce the chance of flooding downstream, especially in short, intense storms.

OSDs may be created above or below ground. In many cases they can be incorporated into car parks, driveways, landscaped areas, underground tanks and pits, or a combination of these. However, you can't usually use a rainwater tank as an OSD.

OSDs will usually be required for:

  • Subdivisions
  • Single dwellings, extensions, additions and improvements
  • Townhouses, villas, home units, duplexes
  • Dual occupancies
  • All commercial, industrial and special use developments and buildings
  • Tennis courts
  • Roads, car parks and other sealed areas
  • Public buildings.

OSDs are usually not required for:

  • Development that increases the impervious surface area of a site by less than 100 square metres. Note that only one exception under this rule is allowed per site.
  • Development within the 1 in 20-year flood extents.
  • Subdivisions of existing dual occupancies where there is no increase in impervious surface area
  • Boundary adjustments and consolidations of allotments where no additional lots are created
  • Change of use where there is no increase in impervious surface area
  • Building additions or internal alterations within the current footprint of an existing dwelling
  • New developments in subdivisions where OSD has already been provided for the entire subdivision
  • Buildings in rural or non-urban areas
  • Developments within OSD Concession Zones, shown on plans in the relevant chapter of the Wollongong Development Control Plan.

If your'e not proposing to use an OSD, you must provide a written justification for this decision with your development application.

In some cases where environmental conditions allow, you may also be able to use alternatives to OSD systems, such as the reuse of stormwater for cleaning or irrigation, using semi-permeable or porous surfaces, or other features that retain water on-site.

For more information on OSDs, including alternative systems, read Chapter E14 of the Wollongong Development Control Plan PDF, 5497.53 KB.

If your development includes on-site stormwater detention (OSD) you will need to include specific information with you application as shown below.

For Development Applications:

  • Stormwater Concept Plan (SCP) including an OSD system
  • The permissible site discharge (PSD l/sec) and the site storage requirement (SSR m3) values for the subject site
  • Refer to the relevant chapter in Wollongong DCP for additional requirements.

See our DA Forms and Checklists for details of other information needed in your development application, or contact us for development advice if you're unsure.

For Construction Certificate (CC) or combined Development Application and Construction Certificate (DA/CC):

  • Detailed stormwater plan including an OSD system
  • The permissible site discharge (PSD l/sec) and the site storage requirement (SSR m3) values for the subject site
  • Construction plans and details of the OSD system
  • Maintenance schedule for the OSD system
  • Plan of the OSD identification plaque
  • Refer to the relevant chapter in Wollongong DCP for additional requirements.

Before a final Occupation Certificate (OC) or Subdivision Certificate (SC) is issued:

  • Work-as-executed plans
  • Certificate of Hydraulic Compliance for the OSD system
  • Structural Certificate for components of the OSD system where applicable
  • Registered documents including the Positive Covenant and Restriction on Use
  • Registered final plan (linen plan).