Rise of the Rain Gardens
– From Portland (US) to Portslade (UK)
Rain Gardens are on the rise, here in the Brighton & Lewes Downs Biosphere now following the evolution of this pioneering concept in the US.
A “rain garden” is simply a low-lying area of ground containing plants tolerant of wetter conditions, that is designed to receive and retain rainfall from surface water run-off from hard surfaces, and then slowly drains away over time to leave them without any open water for most of the year.
This natural way of helping to alleviate local flooding is a form of ‘green infrastructure’, that works in combination with the conventional grey infrastructure systems of drains, pipes and sewers.
Rain Gardens are a type of Sustainable Drainage System, or ‘SuDS’, that can be created both in existing green spaces and as new elements of urban development, to help to reduce flood risk from heavy rainfall events – an phenomenon that is increasing with climate change.
The great thing about Rain Gardens is that they not only hold back storm water and reduce flooding, but they can also help to filter pollution, attract wildlife to your neighbourhood and look colourful at the same time – making them multi-functional in nature.
Although rain gardens are a relatively new idea here in the UK, they began life back in 1990 in Maryland in the United States. Dick Brinker, a housing developer building Somerset, an 80 acre (32 hectare) site for 199 new homes in Prince George’s County, had the idea of replacing four ponds with a series of landscape features, which he felt would be more appropriate in the circumstances.
The US Clean Water Act (CWA) in 1977 had referred to Best Management Practices (BMPs) to control water pollution, and in urban situations the response to this tended to be the creation of sizeable ponds fed by conventional drainage. An over-reliance on ponds by some engineers is still a problem now, 25 years later, indicating how long it takes for new ideas to spread through the professions.
Back in 1990, however, Brinker was aware of examples of industrial and commercial sites where space was limited, where landscaped areas had been modified to allow water to pool for a short time before infiltrating into the soil. Brinker and his daughter Theresa approached Larry Coffman, who was an official at Prince George’s County (the local drainage authority), to seek to modify the drainage plans for the Somerset site, replacing kerbs, pipes and ponds with shallow basins filled with free-draining soils in each building plot. Hanifin Associates, consultants to Prince George’s County, dubbed these infiltration features “Rain Gardens”. The rain gardens were only 25 per cent of the cost of a conventional drainage system and ponds, and the extra space freed up meant that the developer was able to add another 6 or 7 building plots to the scheme. The project was monitored for 2 years, which demonstrated its effectiveness, resulting in the county publishing the ‘Bioretention Manual’ of design for bioretention in storm water management. In 1998, Larry Coffman worked with others to start the Low Impact Development Center to promote the concept of ‘Low Impact Development’ (LID).
Roadside Rain Garden in Portland, Oregon (photo by Dusty Gedge)
Rain Garden replacing pavement in London at Wardens Grove, Bankside (photo by Gary Grant)
Creating the new Rain Garden at Portslade village green (photo by Rich Howorth)
I thought there was a plan for one south of St Peters church in the main valley?
05 Apr 2016 15:06:18
Hi Rob
Various SuDS (Sustainable Drainage Schemes) features have been included in the proposed re-development of the ‘Valley Gardens’ area from St Peters church down to the Old Steine by Brighton & Hove City Council – https://www.brighton-hove.gov.uk/content/parking-and-travel/travel-transport-and-road-safety/a-vision-valley-gardens
This scheme is presently the subject of a review including further modelling studies to assess its feasibility.
06 Apr 2016 14:45:58
Surely it would be better if this was just standard practice everywhere? I always thought that our roads and pavements should be porous to let the rain to drain through.
04 May 2016 20:07:33
Thanks for your comment Debbie.
In parts of the US and Europe ‘sustainable drainage schemes’ (SuDS) such as rain gardens are quite normal practice, using green spaces and replacing some hard surfaces too, but in the UK this is still a relatively new approach – hence our schemes in Portslade being treated as ‘pilots’.
And yes there are permeable paving materials available to use instead of tarmac, which again are starting to be used but they tend to cost 2-3x the conventional alternative hence their use has been relatively limited so far.
Over time I think and hope that both these approaches will be come more mainstream in our Biosphere area.
05 May 2016 09:07:53