STORM Report / WSUD Report

Water Sensitive Urban Design (WSUD) is an approach to urban planning and stormwater management. The aim is to promote sustainable development by managing waterways, potable water use, and ecosystems. This approach is recognized under “Water Quality” and “Stormwater Management” categories for ESD projects. In Victoria, WSUD reports are often referred to as STORM reports, named after the STORM Calculator tool used to demonstrate compliance with stormwater quality target..

WSUD Requirements and STORM Report in Victoria

The Planning and Environment Act 1987 integrates stormwater management into urban developments across Victoria. Specifically, Clause 53.18 requires new developments to comply with best practice standards for stormwater quantity and quality. In Victoria, WSUD reports are commonly referred to as STORM reports.

As a general rule, all new developments that create new hard surfaces (e.g., roofs) must submit a STORM report before obtaining a building permit in Victoria, with some exceptions:

• Single Dwellings: The applicability of WSUD requirements depends on local councils. For example, Yarra Council requires a STORM report for large single dwellings.
• Extension Projects: Some Victorian councils require a WSUD or STORM report for extension projects, particularly when they add at least 50m² of hard surfaces like roofs.

Most stormwater assessments are conducted using the STORM Calculator developed by Melbourne Water. Additionally, BESS includes a built-in tool for water reuse calculations. The MUSIC tool is also used to a lesser extent for stormwater rating.

What is the Stormwater Quality Offset Contribution?

The Stormwater Quality Offset Contribution allows Victorian councils to charge offset contribution fees for developments that cannot meet stormwater management targets. This contribution is available under the following conditions:

1. The development must cover an area of less than 1 hectare.
2. The council must provide written acceptance to Melbourne Water, confirming that Water Sensitive Urban Design (WSUD) treatments cannot be implemented.

These contribution fees help local councils fund the construction and maintenance of infrastructure aimed at improving stormwater management and maintaining waterways.

The required contribution fee is calculated using the Stormwater Offset Contribution calculator, which is based on the achievable STORM rating. For instance, under the current guidelines, the contribution fee for a new development under Yarra legislation is $3.89 per m², multiplied by the achieved STORM rating (%). Therefore, if the development achieves a STORM rating of 50%, the contribution fee is reduced to $1.94 per m².

WSUD Requirements for ESD Reports

If a development in Victoria is required to adhere to ESD (Environmental Sustainable Development) best practice standards, the developer must submit a Sustainability and Design Assessment (SDA) report to the council. This report should demonstrate how the development incorporates Water Sensitive Urban Design (WSUD) practices using tools such as STORM, BESS, or MUSIC. The stormwater management practices can include one or a combination of the following treatments:

• Capturing rainwater runoff with rainwater tanks for toilet flushing and landscape irrigation
• Using permeable pavers
• Filtering stormwater through raingardens or wetlands, which also help reduce stormwater runoff
• Installing greywater recycling systems
• Using green roofs, which also provide passive cooling benefits

A typical WSUD report (STORM report) includes:

• Site Information: General details about the site, including the area of hard and soft surfaces, etc.
• WSUD Commitments: A concise executive summary outlining the commitments to WSUD and stormwater management objectives (e.g., rainwater tanks).
• Treatments: Detailed data, often accompanied by a site plan, illustrating the types of treatments, their capacity, location, and connection to hard surfaces such as roofs.
• Maintenance Considerations: Assessors must provide maintenance guidelines for the proposed treatments and include useful information to ensure their efficient operation.
• Supporting Documents: Includes a site plan, STORM calculator results, MUSIC modelling outputs, etc.

Sample STORM Report

A STORM report outlines the Water Sensitive Urban Design (WSUD) Response to achieve the objectives of stormwater management policy of your local council Planning Scheme.

At Energy Compliance Consultants, we provide WSUD or STORM reports promptly, prioritizing cost-effective solutions for our clients. Our reports are council-ready and visually clear, highlighting the proposed treatments in the most effective way possible. The following Figure shows the location of the catchment areas as well as the proposed treatments from one of our projects:

The following STORM rating report outlines how this application meets the stormwater management objectives of the council’s Planning Scheme. Please note that the required minimum STORM rating is 100.

As shown above, the development did not achieve the required rating of 100. As a result, we opted to purchase a Stormwater Quality Offset Contribution for this project, which amounted to approximately $400.

What is the Best Stormwater Treatment?

There is no one-size-fits-all solution for stormwater treatment across Australia. The best approach depends on factors such as the project’s size, budget, the extent of hard surfaces, and potable water usage. However, based on our experience, the following treatments are cost-effective and align with ESD (Environmental Sustainable Development) initiatives:

• Rainwater Tanks for Toilet Flushing: While rainwater tanks are not primarily a stormwater treatment solution, they play a key role in water conservation and can reduce rainwater runoff. Although they don’t significantly improve stormwater quality, rainwater tanks offer a dual benefit: they reduce stormwater runoff and decrease potable water consumption for toilet flushing and landscape irrigation. This makes them an effective solution for meeting both water use and stormwater treatment goals.

• Raingardens for Small and Medium-Sized Developments: Raingardens are a popular, cost-effective, and efficient option preferred by councils for meeting stormwater management Best Practice Standards. These small basins, typically filled with plants, help settle large debris, filter pollutants, and reduce runoff to waterways. For small developments, raingardens are particularly efficient; they can achieve high stormwater ratings with an area as small as 2m².