Levee banks FAQs

The project includes:

• 100m earthen and concrete levee at Central Cabins and Van Park in Castlemaine
• 430m earthen and concrete levee at Elizabeth Street in Castlemaine
• 580m earthen and concrete levee at Campbells Creek township
• 50m earthen levee at National School Lane in Campbells Creek
• Waterway improvements downstream of Alexandra Street bridge in Campbells Creek.

Consultants GHD determined the best locations for levee banks and waterway works based on flood modelling through the development of the Flood Management Plan. As part of this work they investigated historic flood information and conducted hydrological, hydraulic, flood damage and flood mitigation option assessments.

Introduced trees such as willows will be removed downstream of the Alexander Street bridge. Some native saplings in the middle of the creek will be removed to improve water flow and the health of the creek. Native plantings will be added along the edge of the creek. Council has liaised with local Landcare group Friends of Campbells Creek to undertake these works, which are included in a landscape design plan.

The main beneficiaries of these levees are nearby residents and businesses who will have will greater protection from floods. The works will also protect public infrastructure such as roads, footpaths and public buildings.

Council will carry out a detailed boundary re-establishment survey to map the exact location of the levee banks in relation to property boundaries. Some properties may have encroached beyond their boundary onto Crown Land. In these cases Council in partnership with the Department of Environment, Land, Water and Planning (Crown Land owners) will contact property owners directly to resolve the encroachment.

Construction will depend on how long it takes to obtain approvals and secure funding. The earliest that construction could occur would be February 2024.

Estimates in 2017 indicate construction costs to be around $2.5 million. Council will investigate an up-to-date cost estimate as part of the Development phase. It is likely to capture some costs that were not previously assessed.
As with other infrastructure projects, Council will pursue funding through Federal and State grants. Grant funding typically requires a minimum of one-third funding contribution from Council.

The Castlemaine, Campbells Creek and Chewton Flood Management Plan outlines recommendations to reduce the risk of localised flooding. It includes a summary of the assessments, inputs and flood modelling that was carried out to inform the recommendations.

Castlemaine, Campbells Creek and Chewton have a well-documented history of flooding of Barkers Creek, Forest Creek and Campbells Creek. In the last ten years the towns have been impacted by four major rainfall events in 2010, 2011 and 2012. Due to the widespread impact of the floods on homes, businesses and community assets the Victorian Government provided funding to develop the Castlemaine, Campbells Creek and Chewton Flood Management Plan to identify ways to reduce the impact of flooding on the community.

Consultants GHD developed the plan. The plan North Central Catchment Management Authority (North Central CMA) is the lead agency in the area for coordinating and monitoring the region’s rivers. The authority worked with Council to engage GHD.

The recommendations were to:

1. Install a levee bank near Castlemaine Central Cabin and Van Park and Bruce Street (this project).
2. Install a levee bank along Elizabeth Street in Castlemaine (this project).
3. Install a levee bank to protect the township of Campbells Creek (this project).
4. Install a levee bank at National School Lane in Campbells Creek (this project).
5. Undertake waterway improvement works downstream of the Alexandra Street bridge at Campbells Creek (this project).
6. Install a levee bank along the north of Gingell Street in Castlemaine (not included in this project. It requires further community engagement and design consideration and will be handled as a separate project).
7. Install a levee bank along the south of Gingell Street (not included in this project. It requires further community engagement and design consideration and will be handled as a separate project).
8. Carry out strategic planning for urban waterways (complete).
9. Investigate a flood warning system (complete – integrated into the Mount Alexander Shire Municipal Flood Emergency Plan).
10. Amend the Mount Alexander Planning Scheme (complete).

GHD specialists reviewed the available data and historic flood information and carried out a hydrological assessment and hydraulic assessment. They also assessed the flood damage and devised and tested options to reduce the impact of flooding. They worked with the community to gain feedback and consensus on the best options.

Community engagement was a key element in the development of the Flood Management Plan and its recommendations. This occurred over the course of the study through community information sessions, a public questionnaire, media updates and meetings with the Technical Working Group and community-based Steering Committee.

In their assessment, GHD looked at structural and non-structural options to provide flood protection, with consideration given to community recommendations. Structural options included levees, structures (improving flow conditions under bridges), waterway management and storage (retention basins, deepening of existing storage). Non-structural options considered land use planning, flood warning and flood response measures.

As part of the benefit-cost analysis there was not found to be a levee design for Chewton that would provide substantial protection from localised flooding

The Newstead levee bank project is being managed separately. Council will provide more information on the project as it progresses.

One way to measure floods is to look at how often they are likely to occur. The Annual Exceedance Probability (AEP) is the probability or likelihood of an event occurring in any given year. For example, a 1% AEP means there is a 1% chance of a flood of that magnitude occurring in a year.

The Castlemaine Cabin and Van Park, Elizabeth Street and Campbells Creek Township levees are designed to provide protection against a 1% AEP (or event that has a 1% probability of occurring in a year). The levees also have an additional 300mm of freeboard which protects against variables such as waves and waterway obstructions that may increase the water level locally during a flood.

The National School Lane levee is designed as a velocity levee which aims to prevent land washing away during a flood event. A design AEP is not specified for this levee.