Lithgow Floodplain Management
Reducing the risk of future flooding requires community and Council working together to manage flood prone areas properly with responsible development, drainage infrastructure and the sharing of information.
How are floodplains being managed in NSW?
The State Government’s Flood Policy is directed at providing solutions to existing flooding problems in developed areas and to ensuring that new development is compatible with the flood hazard and does not create additional flooding problems in other areas.
Under the Policy, the management of flood liable land remains the responsibility of local government. The State subsidises flood mitigation works to alleviate existing problems and provides specialist technical advice to assist councils in the discharge of their floodplain management responsibilities.
The Policy provides for technical and financial support by the Government through the following four sequential stages:
|1 Flood Study
|Determines the nature and extent of flooding.
|2. Floodplain Risk Management Study
|Evaluates management options for the floodplain in respect of both existing and proposed development.
|3. Floodplain Risk Management Plan
|Involves formal adoption by Council of a plan of management for the floodplain.
|4. Implementation of the Plan
|Construction of flood mitigation works to protect existing development. Use of Local Environmental Plans to ensure new development is compatible with the flood hazard.
Lithgow Flood Study Review
The Lithgow Flood Study Review is jointly funded by Lithgow City Council and the NSW Government, via the Office of Environment and Heritage. The Flood Study Review constitutes the first stage of the Floodplain Risk Management process for this area and has been prepared for Council to define flood behaviour under current conditions.
What was the objective of the Flood Study Review for Lithgow?
The study objective was to review and update the hydrologic and hydraulic modelling for the Farmers Creek catchment to define the nature of both Main Stream Flooding and Major Overland Flow in the urbanised parts of Lithgow for floods up to the Probable Maximum Flood. A requirement to provide similar information in future growth areas led to the development of new hydrologic and hydraulic models for the adjacent catchment of Marrangaroo Creek.
The information presented in the report will form the basis for the preparation of the future Floodplain Risk Management Study and Plan for Lithgow. The Floodplain Risk Management Study and Plan will assess the economic impact of flooding on existing urban development, review options for flood mitigation and prepare a plan of works and measures for managing the present and future flood risk in Lithgow.
Where does Main Stream Flooding occur in Lithgow?
Main Stream Flooding in Lithgow occurs when flow surcharges the channels of Farmers Creek and Marrangaroo Creek, as well as their major tributaries. These flows may be several metres deep in the channels and relatively fast moving. Main Stream Flooding also occurs when flow surcharges the major pipelines that have been laid along the routes of natural channels as the catchments have urbanised.
Where does Major Overland Flow occur in Lithgow?
Major Overland Flow results from runoff which travels as either sheet or concentrated flow over grassed and paved surfaces in individual allotments, or along roads en-route to the trunk drainage system, or surcharges the minor pipes in the catchment headwaters and the lateral sub-catchments bordering the trunk drainage systems. Major Overland Flow is limited to areas affected by depths of flow greater than 100 millimetres.
What is the Probable Maximum Flood?
The Probable Maximum Flood is the largest flood that could conceivably occur at a particular location, usually estimated from probable maximum precipitation coupled with the worst flood producing catchment conditions. The Probable Maximum Flood defines the extent of flood prone land (i.e. the floodplain). The extent, nature and potential consequences of flooding associated with events up to and including the Probable Maximum Flood should be addressed in a floodplain risk management study.
What has been defined as flood prone land in Lithgow?
Flood prone land in Lithgow has been defined as land which is inundated to depths greater than 100 millimetres during a Probable Maximum Flood event. It comprises areas that are affected by both Main Stream Flooding and Major Overland Flow.
What is the Interim Flood Planning Level for Lithgow?
The Interim Flood Planning Level for Lithgow is a combination of flood level and freeboard which has been selected for planning purposes. Pending the completion of the future Floodplain Risk Management Study for Lithgow, it is equal to the peak 1 in 100 year flood level plus 500 millimetres freeboard. The Interim Flood Planning Level has been defined along the major overland flow paths in Lithgow, as well as in areas subject to Main Stream Flooding.
What is the Interim Flood Planning Area for Lithgow and how does it affect my property?
The Interim Flood Planning Area for Lithgow is defined as land which lies below the Interim Flood Planning Level. Properties which lie either partially or wholly within the extent of the Interim Flood Planning Area (i.e. land which lies below the Interim Flood Planning Level) will be subject to S149 flood affectation notification, and as such subject to the flood related development controls set out in Clause 7.2 of the Lithgow Local Environmental Plan, 2014.
The Interim Flood Planning Area (IFPA) for Lithgow (refer to LFSR Report Vol 2 Figure 6.16 Sheets 1-4 for extent) has been derived as part of the present investigation for areas subject to both main stream flooding and major overland flow.
What are the next steps in the process?
Council, subject to funding will undertake the preparation of a Floodplain Risk Management Study and Draft Plan for Lithgow. The Floodplain Risk Management Study will evaluate management options for the floodplain in respect of both existing and proposed development.
This will include the assessment of various:
- flood modification measures such as levees, trunk drainage upgrades and channel improvements;
- property modification measures such as the development of a grade set of prescriptive flood related development controls which would apply to future development located on flood liable land; and
- response modification measures such as improvements to flood emergency planning and weather warning systems, and the implementation of a flood awareness and education program.
A Draft Floodplain Risk Management Plan would also be prepared as part of the study, which would set out a preferred set of measures which are aimed at managing the flood risk in Lithgow. Upon adoption of the Draft Floodplain Risk Management Plan by Council, funding can then be sort from the NSW Government for its implementation.
While a date has not been set for the commencement of the Floodplain Risk Management Study and Draft Plan, its preparation would typically take between 12-18 months to complete. Input from the local community will be sort at the commencement of the study on the range of potential measures which could form part of the Draft Floodplain Risk Management Plan. The community will also be given an opportunity to comment on the Floodplain Risk Management Study and Draft Plan prior to its adoption by Council.
My property was never classified as ‘flood prone” or “flood liable” before. Now it is. Why?
The Lithgow Flood Study Review has a wider and more comprehensive scope of investigation than previous flood reports. This study includes Farmers Creek catchment and the catchment of Marrangaroo Creek to define the nature of both Main Stream Flooding and Major Overland Flow in the urbanised parts of Lithgow and future growth areas for floods up to the Probable Maximum Flood.
This is why more properties, some of which are a long distance from any natural channel, are now identified as being flood prone.
What if I disagree with the flood mapping for my area?
Council has used up-to-date modelling techniques, as well as expert assistance from consultants and the NSW State Government, to determine mapping and analysis of risk. Council believes our flood level estimates are as accurate as possible at this point in time.
If you believe that are not correct for your property, you can seek professional advice relating to your property and request Council to review.
How do I find out what the flood level is for my property?
If your property has been included in the Lithgow Flood Study Review Report, Council’s duty planners can assist you to identify the 1% AEP flood level, the interim flood planning level and area, the flood hazard and hydraulic category and other relevant data from the computer modelling data that supports the report.
Flood Development Controls
All land at or below the flood planning level will be subject to flood development controls. These are specified in Clause 7.2 of the Lithgow Local Environmental Plan 2014 and will eventually be more detailed in a comprehensive development control plan.
What are the flood related development controls – Lithgow Local Environmental Plan 2014?
Flood related development controls are currently located in Clause 7.2 of Lithgow Local Environmental Plan 2014.
Following adoption of the Lithgow Flood Study Review report LLEP2014 – Clause 7.2 will apply to land now identified within the Interim Flood Planning Area as shown in Figure 6.16 Sheets 1-4 of that report. This includes land previously identified by the Flood Planning Map and new identified areas.
NOTE: THE NEW INTERIM FLOOD PLANNING AREA IS MORE EXTENSIVE THAN LAND IDENTIFIED AS “FLOOD PLANNING AREA” ON THE FLOOD PLANNING MAP INCLUDED IN THE LITHGOW LOCAL ENVIRONMENTAL PLAN. Council is working towards amending this mapping.
Will I have to undertake a flood risk report when I want to develop my land?
It depends on the scale of development. It may mean that your development will need to provide a flood risk report prepared by a professional hydraulic engineer to certify the development and address the objectives of Clause 7.2 of the Lithgow Local Environmental Plan 2014.
The relevant information such as flood levels and hydraulic hazard from the flood study can be made available to assist in completing any further more detailed site specific studies/reports
Flooding and Exempt Complying Development Codes
You do not need planning or construction approval for many minor renovations and low-impact works (exempt development). Council approval is not needed if your project meets specific development standards.
This is not affected by Flood Planning Controls.
Complying development is a fast-track approval process for straight forward residential, commercial and industrial development. If the application meets specific criteria, it can be determined by a council or accredited certifier.
You can carry out complying development on flood prone lots, subject to the requirements of the relevant Code. Refer to Clauses 3.5; 3A.38 and 5A.30 under the relevant Codes specifying development.
Essentially complying development under the Housing Code; Rural Housing Code and Commercial and Industrial (New Buildings and Alterations Code) must not be carried out on any part of a flood control lot, other than a part of the lot that the council or a professional engineer who specialises in hydraulic engineering has certified, for the purposes of the issue of the complying development certificate, as not being any of the following:
(a) a flood storage area,
(b) a floodway area,
(c) a flow path,
(d) a high hazard area,
(e) a high risk area.
The Lithgow Flood Study Review Report has identified and mapped the key flood hazard zones and floodways and hydraulic hazard within the Study area. You are encouraged to make initial enquiry with Council’s Duty Planners who can assist in providing this information for site specific areas.
Flood Planning Notations and Section 149 Planning Certificates
What is a Section 149 Planning Certificate?
A Section 149 certificate is a Planning Certificate which is specific to each individual property. Under NSW legislation a contract for sale of a property must include a S149 certificate from the relevant local Council. There are two types of s149 certificate:
- S149 (2) certificate: contains information specified in Schedule 4 of the Environmental Planning and Assessment Regulation 2000. Among other things this will include information relating to planning instruments; development control plans; zoning and landuse; heritage items; road widenings; flood related development controls; bush fire prone land and land reserved for acquisition.
- S149 (5) certificates: provides the above s149 (2) information plus advice on other relevant matters affecting the land that Council may be aware of.
Why does Council put notations on S149 Certificates?
Council has a responsibility to inform the community and future property owners as clearly as we can about potential risks to life and property, and to help limit damage from flooding now and in the future.
Council also has a legal and moral obligation to let current and future owners know about development controls that may apply to specific property. Any property identified as being flood prone and that may attract development controls will have a flood notation on its s149 certificate.
How does Council determine which properties are flood prone to notate on S149 Certificates?
Flood prone land to be notated on s149 Certificates in the Lithgow LGA is identified by Flood Studies. The Lithgow Flood Study Review (LFSR – Lyall and Associates May 2017) is the most recent and comprehensive flood study available to Lithgow City Council.
This does not mean other land in the LGA outside of the LFSR area is not flood prone it just means we do not hold any flood studies or definitive flood levels for that land.
Does having a flood notation mean I can’t develop my land?
It is unlikely that development controls will prohibit all development on land on flood prone land. However, some factors may need to be taken into consideration in any future development to alleviate risk to life and property. For example, you may be asked to build on a certain part of your land or elevate your building to a certain height. Council’s development assessment team can help you understand these considerations.
Will the notation affect the value of my property?
Because individual property values are based on many factors and the impact of flood development controls varies greatly from one property to another, it’s impossible to predict whether a notation will affect property values. The notification may affect one potential buyer’s decision to purchase a property but for another it may have no impact. Studies have shown that an actual flood event rather than a flood planning notation, is more likely to have an effect on property values.
A notation on the s149 certificate will not change how flood prone a particular property is.
A major advantage of appropriate notation of flood risk is that it should ensure that your neighbour, or even other land within the catchment is developed in such a way that it does not divert or increases flood waters onto your property that would disadvantage your property and potentially reduce value.
All flood information Council has is freely available through our website or upon enquiry with Council’s duty planners.
Will a notation cause my insurance premium to rise? Do I need to tell my insurance company?
Council is not in a position to advise you on this matter, your policy is a matter between you and your insurer. You will need to contact them directly. Flood insurance is based on the level of risk and consequent damages from flooding and this will not change as a result of Council’s studies.
Flood insurance is not widely available for residential properties in Australia. Many insurance companies do not provide flood cover as part of their insurance products. Other insurance companies provide flood cover as an optional extra. Individual insurance companies typically identify flood prone land and assess risk through their own studies, analysis and flood mapping exercises, (irrespective of whether Council has undertaken a flood study) with the information then used to set policies and premiums. These calculations are outside Council’s control.
Councils have responsibility for identifying and then managing the risk to life and property from flooding, and have a duty of care to disclose this information to the community. Council’s flood study represents significant advances on previous site based investigations, which all members of the community, including insurance companies, are able to access. These studies may be used by insurance companies to refine their flood profiles, potentially excluding properties that would otherwise be included through more risk-averse calculations.
The flood study maps show only a small part of my property is affected, so why has it been classified as flood prone?
The Study maps highlight which properties are expected to be affected by flooding. Even if a small portion of the property is affected, the whole property area will be classified as affected and will notated on a S149 certificate. Development controls are applied to a whole property and cannot be split, regardless of flood extent, however application of the control depends on where on the property the proposed development is located, and what type it is.
What Can I do to Prepare in Case of Floods?
The State Emergency Service has a useful website providing advice on how to manage flood risk. Visit www.floodsafe.com.au for more information.
Where can I find out more?
To find out more information or to request site specific information and mapping please contact Council’s duty planners at Council’s Administration Centre or phone 02 63549999.
Council provides all information it holds in relation to flooding in “good faith” and is protected by the provisions of s.733 of the Local Government Act from any liability that it may incur as a result of that information.