The Rain Garden Retrofit

I’ve wished for years that I could do this out the front of my house, and after researching this post I think I now have enough ammo to get started.

One thing that typifies our neighbourhoods is expanses of lawn between footpath and road, with extruded concrete kerb-and-gutter supported by some significant storm water piping. I’ve posted about rain gardens before in a strictly built up urban context [NYC Bioswales], so this post has more of the suburban emphasis.

rain garden retrofit

Adams Street Rain Garden Project, Madison, Wisconsin US

Rain gardens are landscaped storm water soakage swales or ponds, often constructed alongside roads, car parks and pavements but also in front and rear lawns.

A study conducted around 10 years ago in the US compared a ‘rain garden street’ with a control street around the corner. The rain garden street installed a number of rain gardens within the existing lawn kerbs, at an approximate cost of $7,500 per household. The results, after several years of gathering data, showed that the rain garden street had reduced its total storm water run-off by 90% (!).

Something I love about this rain garden concept is that it is completely adaptable, stage-able and scale-able, it can form part of a new residential street layout or it can be retrofitted into an existing one.

Rain gardens are an investment with multiple benefits;

  • significant reduction in storm water management costs – for new developments this could significantly reduce the cost of storm water infrastructure;
  • increase in groundwater re-charge, making more water available for street trees;
  • increase in street planting, reducing heat island effect and improving local microclimate, habitat and street pavement life;
  • uplift in real estate value – personally I think this is the big one… presentation is everything and a street full of landscape and healthy trees is always going to have increased value, regardless of what’s inside the houses. People pay for good places and streetscapes;
  • community building – typically the retrofit rain garden projects are initiated and delivered by local residents groups, so the investment is in their community as much as it is in the green infrastructure.

rain garden

I suspect a lot of us are already tinkering with this concept under the heading of Water Sensitive Urban Design [WSUD], but a quick trawl for ‘rain garden’ images online reveals that there’s a lot more to this than just managing water. It’s at the same time an environmental bonus and, when done well, a real estate booster.

Next step for me is giving my local Council a call to see what they think. If you don’t ask you don’t get.


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