Water Sensitive Urban Design (WSUD)

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Water sensitive urban design (WSUD) is a landscape design approach to integrating stormwater into urban design to mitigate against flooding, improve amenity, replenish groundwater and improve the quality of stormwater entering the marine environment.

Water sensitive urban design (WSUD) is a landscape design approach to integrating stormwater into urban design to mitigate against flooding, improve amenity, replenish groundwater and improve the quality of stormwater entering the marine environment.

  • Tree Inlet information

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    27 Oct 2020
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    Farr Terrace in Glenelg East is one of many streets across Holdfast Bay that will benefit from upgrades to manage and recycle stormwater.

    TreeNet Inlets are being installed into the kerb and are designed to take rainwater and return it to the ground to provide a water source for our trees, rather than let it pool in the gutter or go out to sea.

    The same program will start in Chopin Street, Somerton Park at the end of the week, followed by McFarlane and Leak Streets in Glenelg North and Oxford Street, Brighton in November.

    Residents can help the functionality of the inlets by occasionally sweeping away debris and, in summer, regularly filling the TreeNet Inlet collection pit with a bucket of water or filling it with water from a hose.

    What are TreeNet Inlets?

    TreeNet Inlets are small, unobtrusive stainless steel grates which are installed into the side of the kerb to collect rainwater. The grate is connected to an underground collection pit in the verge, which collects rainwater to water the nearby trees.

    What are the benefits of installing TreeNet Inlets?

    Reducing water ponding TreeNet Inlets are strategically placed in low lying areas to reduce long-term stormwater ponding. Instead of rainfall ponding on the kerb or in the road, the water will be diverted into the ground to water our trees and replenish the aquifer.

    Keeping our street trees healthy By diverting rainwater into the ground, the street trees will have access to a passive source of irrigation as they grow in our urban environment. Over time, we anticipate that tree roots will find this favourable source of water and become more resilient and healthy.

    Providing additional environmental benefits Healthier street trees not only make for a cooler urban environment, they also have flow-on effects including reducing carbon dioxide, providing more oxygen, protecting us from harmful ultra violet rays, increasing property values, and improving our wellbeing. By diverting rainwater to the trees, it also reduces the amount of stormwater that would otherwise flow out to sea.

    What can you do to help the TreeNet Inlets?

    In summer, you can help our street trees by regularly filling the TreeNet Inlet collection pit with a bucket of water or filling it with water from a hose. The City of Holdfast Bay has a scheduled program to water our young trees, but any additional water that you can provide to the trees will support their growth.

    In winter, an occasional light sweep across the grate will unclog the exterior of the inlet of any leaves or debris which may build up over time. This will ensure that rain continues to flow into the inlet and water our trees, and help to eliminate long-term water ponding on the road. The City of Holdfast Bay’s maintenance team will also continue to regularly undertake street sweeping to keep the gutters clear.

  • Rain Gardens

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    by yv at holdfast, 21 Mar 2019
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    Rain gardens are a great WSUD initiative. Here are some of the reasons why.

    Have you ever wondered what happens to the rain water before its goes into the ocean...?

    Many people think the storm water gets captured, treated and returned to the water supply but in reality it goes through our gutters and down pipes, across lawns, driveways and roads and then enters the ocean through our outlet pipes. At each point along this process the stromwater picks up debris and pollutants that all get washed out to the ocean too.

    In nature the rainwater infiltrates into the streams and rivers through the aquifer and natural waterways which keep a generally constant and steady supply of flowing water all year round that finally arrives at the ocean ready for the water cycle and precipitation to start all over again.

    In our urban environments stormwater is hindered from entering the aquifer through ground water infiltration and is generally diverted into our stormwater pipe networks. These networks are designed to take water directly to the ocean which misses out some of the key steps of the natural model. Therefore the water flows can occur in irregular patterns of high and low flows which are often too much for the stormwater syPicture Source: NYC Environmental Protectionstem to handle. This can cause heavy erosion to our waterways, sediment build up and flash flooding.

    Rain gardens can help to solve all of these issues. By creating rain gardens we are effectively putting part of that natural water process back into the storm water system.

    What is a rain garden?

    A rain garden is an area of deep rooted plants, vegetation and even trees that is designed to temporarily capture stormwater runoff so it can infiltrate the soil and feed the plant life.

    Benefits of rain gardens:

    • providing habitat for flora and plant pollinators
    • reduce stormwater surges
    • reduced pollution to the oceans
    • better looking streetscapes
    • pollutants in stormwater are used as nutrients through plant uptake
    • reductions to potential flooding and water pooling

    With stronger rainfall patterns predicted due to climate change our stormwater systems are now more important than ever. Rain gardens and other WSUD treatments are a great way to reduce the demand on the stromwater network. Not only do they assist with the stormwater management but they offer urban greening efforts and kerb appeal.

    As a resident you too can get in on the action and look at adding a rain garden to your property improving your landscape and helping to assist with stormwater management to both your property and your community. Visit www.melbournewater.com.au/community-and-education/help-protect-environment/raingardens for factsheets and advice on building your own rain garden.


  • Tree Net Inlet Pits

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    by yv at holdfast, 21 Mar 2019
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    What is a treenet inlet pit?

    A tree net inlet pit is small unobtrusive grate and dish in the kerb and water table.

    The grate goes horizontally through the kerb and into the verge which collects rainwater that flows along the roads kerb and water table. The grate is connected to a concealed collection pit in the verge that then filters the rainwater out into the verge which feeds the tree roots.

    The dish is located in the water table and acts as a small collection point for the kerb grate. This dish also acts as a mini vortex which throws out big leafs and other debris so it does not clog up the grate.

    Benefits of tree net inlet pits:

    • promotes tree health
    • reduce rain water pooling
    • reduce stormwater surges
    • reduced pollution to the oceans
    • pollutants in stormwater are used as nutrients through tree uptake


  • Permeable Paving

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    by yv at holdfast, 21 Mar 2019
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    Picture Source: www.fixsproject.com

    Permable paving is another great example of a WSUD implementation. Permeable paving is a way of paving that allow storm-water to infiltrate and return to groundwater. Ideally, permeable paving systems help to manage water run-off, isolate solid substances and trap the pollutants in the underlying layers which can improve water quality.