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Creating a more resilient, safer community

 

 

Townsville is known for its unpredictable Summer weather conditions and a recent wild rain event, has highlighted how vital our Elliot Springs' Stormwater Management Plan (SMP) is in protecting our community from the impact of storm and flood waters.

Through smart land planning and sustainable practices, Elliot Springs has adopted water sensitive urban design principals and mitigation strategies to ensure the ongoing safety of our residents and their homes.

We sat down with Lendlease Development Director, Simon Walker to talk about the importance of creating a resilient community, that can withstand the unpredictable north Queensland weather conditions.

 

Can you explain the importance of Elliot Springs having a stormwater mitigation strategy?

Elliot Springs has developed a Stormwater Management Plan (SMP) which has two components, stormwater hydraulics (flooding) and stormwater runoff quality (sediments and nutrients).  The hydraulics component of the SMP ensures that the land developed at Elliot Springs is not inundated by any storm event up to and including what is often referred to as a 1 in 100 year event.  This helps provide some peace of mind for residents, that during heavy monsoonal rain which we experience yearly, the drainage system designed will work and the housing will not be subject to flooding.

 

What happens when we get heavy rain in Townsville and how does Elliot Springs relieve the flooding risk?

The Stormwater runoff from heavy rain is channelled from houses to the roads within Elliot Springs, which in turn convey the runoff to the gully inlet pits and pipes.  The stormwater pits and pipes, work in combination with the grading of the roads to covey stormwater runoff into the natural watercourses at Elliot Springs.  This design methodology ensures that the risk of flooding at Elliot Springs is minimised. 

 

Example of a retained creek corridor

 

What is involved in the stormwater mitigation strategy?

The Elliot Springs gullies and creeks, including the bio-retention basins and roads, are dual purpose with regard to the stormwater mitigation strategy.    While this infrastructure is designed to remove the stormwater runoff from Elliot Springs and prevent flooding, this stormwater infrastructure has a secondary use, that of a water storage device which in turn reduces the peak levels of each storm event – similar to the effect a weir has on a river.  

 

Examples of new planted bio-retention basins

 

What is the adopted water sensitive urban design principals?

Water sensitive design is in essence utilising the stormwater runoff to the best advantage of the Elliot Springs environment while maintaining the runoff quality to that which occurs naturally.  Sediments generated by stormwater runoff during construction are removed using proven construction techniques, soil modification products and sediment control devices.  Very fine soil particles which become suspended in the stormwater are removed either capturing the stormwater and allowing the sediment to settle out or using a flocculant to speed the settlement process up. The stormwater nutrient runoff is filtered through either the grass swales and creeks at Elliot Springs or through the purpose-built filter media in the bio-retention basins. 

 

Example of a culvert, which are designed to hold back water during storm events to minimise flood downstream

 

Why are bio-retention basins so important?

Bio-retention basins are specifically designed to provide two functions. The first function is to retain a significant volume of stormwater for treatment and the second function is to continuously filter the stormwater to remove nutrients.  The bio-retention basins have a specifically designed filter media which removes the excess nutrients from the stormwater before discharging the stormwater into the gullies and creeks of Elliot Springs.  The plants in and surrounding the bio-retention basin take up the nutrients that have been removed. 

 

An outlet from one of our bio-retention basins

 

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