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Constructing a Rain Garden

Water in the garden can be a blessing and a curse. While it’s great for plants, when it gets under houses it’s not so helpful. When we took on this job on a sloped property in Geelong one of the first issues identified was the water coming down the hill and under the house. One option would have been to put in a perforated agricultural drain pipe (agi-pipe) and divert the water into the storm water network. With the clients blessing we chose to make a feature rain garden in front garden. Rain gardens help treat and slow the flow of water before it gets into storm water systems and local water ways. Installing a rain garden also enabled the water to be accessible to the new tree planting in the front garden.

 

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The site before we started work

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We called in the big equipment to dig out the base of the rain garden

 

 

 

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The depth of the trench gradually reached 600mm (2ft) at its deepest point.Rain Garden 18

 

The rain garden is fed by water collected in underground agi pipes across the back and down the side of the residence.
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The trenches for the pipe were filled in with scoria

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This image shows the agi-pipes at work. The water makes it’s way down the hill and into the trench before being redirected into the rain garden at the front of the property.

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Once covered in toppings and garden beds the drainage system is invisible.
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The agi-pipe is flexible enough to curve around the front of the house


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The drainage trench meets up with the main rain garden


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The base of the rain garden is filled with a deep layer of large scoria stones which water filters through easily

Rain Garden 12The scoria is then covered with a layer of fine screenings which prevent the later soil layer mixing with and clogging up the scoria

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A layer of half sand half loam is then added as a growing medium for planting 


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You can use many types of mulch for a rain garden, in this case we were going for a stylised dry river bed and chose washed river stones.


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Rain Garden 1

We installed a bridge to enable access to the other side of the garden and not disturb the workings of the rain gardenRain Garden 3

The rain garden was then planted out with native grasses that are tolerant of both drought and inundation.

Rain Garden 2Then we added some sculpture because that’s just fun.

 

If you want any more information of rain gardens or other ways to use water better in the garden contact us here or via the form below.