One of the networks that Slow The Flow is part of is the excellent White Rose Forest. Recently, our trustee Pat Devine went along on a visit with the ‘Green Streets’ group, to see the fantastic urban rain gardens in Sheffield city centre.
Mike Batley, the Green Streets Development Manager, who organised the event, has written about their experience in this inspiring guest blog post:
The Hanging Gardens of Babylon, the Gardens of Versailles, Vancouver’s Butchart Gardens, Sheffield’s Rain Gardens…excuse me?!
It may seem fanciful to speak of Sheffield alongside these iconic garden locations. But then again, having just had the privilege of a guided walk around Sheffield’s Grey to Green sites, I think there is a strong case that can be made to talk about this local network of greenspaces in the same sentence.
As the White Rose Forest’s Green Streets® Development Manager, one of my roles is to establish a network of learning across urban professionals in the WRF’s area. A group of around 20 representing WYCA, most West Yorkshire districts, and Slow the Flow was joined by three of the WRF team. We all benefitted from the hospitality and expertise of Arup and their staff, particularly landscape architect Zac Tudor who was the key designer and driving force behind the transformative ‘Grey to Green’ programme in his time at Sheffield City Council.
The context for this work can be traced back to the floods of 2006 when the River Don burst its banks. But for over a decade before that, Sheffield city centre had been in decline, Meadowhall dominating the retail offer and it was increasingly the metaphorical hole in the centre of the ring road’s donut. So, it was imperative to create spaces that did more than just manage water, especially for the life of the city.
There is no meaningful way to condense the process that was then undergone into a short piece like this. Perhaps the only option is to pick a few highlights as an illustration of what has been achieved overall.
Spaces have been designed for multiple functions; one area that is alongside an outdoor play area has been designed effectively as a ha-ha, to act both as a SuDS feature, but also to protect the play area from reckless vehicular threats.
Species were chosen to be functional but also aesthetic. In spring there is plenty of floral colour, and a wide variety of grasses and leaf forms to make the beds attractive. Zac made no apologies for the prevalence of non-native plants – ensuring function, plant resilience and the security of the investment were all necessary outcomes. Happily most species are enjoyed by pollinators which is another success.
Plants were selected to be drought resistant and suit low-fertility conditions as they were planted into a gravel substrate to encourage good drainage. A lot of success was down to understanding site conditions – so the structure and fertility of the soil, the anticipated moisture levels, the exposure of the sites to wind and sun. In that respect knowing the local conditions is critical to success, but the principles of good design are universal.
Surface water is always directed into the rain gardens off hard surfaces through dropped curbs and rills.
Depending on local run-off rates, individual rain gardens have in some cases been linked by pipes to increase their capacity, with dams extending under the soil to hold more water back before overspilling into the next rain garden downhill.
This also filters the run-off so the water discharging into the River Don is clean and not adversely affecting the river and its habitat.
After an initial period of establishment, the only meaningful maintenance of the whole network is a cut and rake of the ground vegetation in February. Arisings are composted.
Sheffield’s maintenance contractor Amey has stated it is cheaper to maintain the green infrastructure rather than the equivalent grey.
The spaces have been shown from user surveys to be restorative and encourage walking – people have stated they walk further just to enjoy being able to walk through the rain garden areas. zFrom our observation alone, shops or no shops, there were plenty of people on foot and bikes enjoying the benefits of being that bit closer to nature.
In fact, I can say as a resident of Sheffield 30 years ago, I found the city centre to be barely recognisable such has been the degree of change.
Has the work been a success? You bet; what measure do you want to use? The Grey to Green spaces are functional, attractive to people and insects, create a distinctive sense of place, are not onerous to maintain and encourage other investment in green space, not just in Sheffield but much further afield. One can only hope the impact was enough to encourage copycat projects in West Yorkshire, especially with the vulnerability to surface water flooding in many areas.
The fame of Sheffield’s Grey to Green has spread too, with Zac telling me about one occasion when a Japanese party asked for a guided visit as part of visiting some of the best urban regeneration schemes in Europe.
I’m sure they were as impressed as the Green Streets® party from West Yorkshire…
Glossary:
WRF White Rose ForestWYCA West Yorkshire Combined Authority