Sheffield
Grey to Green
By: Frank Landman
Grey to Green project Sheffield, United Kingdom The Grey to Green project in Sheffield is the UK's largest inner-city 'green street'. The project started in 2014 (1.6 km), currently phase 2 is under construction. The project runs along a dual carriageway in the city centre, which runs along the edge of Sheffield city centre. Previously, this highway was part of the main inner ring road, but the construction of an outer ring road in 2010 relieved the traffic pressure so much that some lane space could be surrendered and two lanes are sufficient. This vacant space was then filled in with, among other things, rain gardens and wadis and widened sidewalk spaces for pedestrians One of the main functions of the Grey to Green project is to reduce and slow down the discharge of surface water. The route runs next to the River Don and is located in a part of the city that is prone to flooding. In 2007, this part of Sheffield was flooded, causing major economic damage. The grey-green plan is partly designed to reduce the amount of surface water discharge that reaches the River Don. The project aims to increase urban biodiversity and create a corridor for animals, protect pedestrians from air pollution through multi-layer planting, achieve urban cooling through more tree planting, treat polluted water and promote health and well-being. But in addition, an important aspect was that it would also be an incentive and catalyst for further investment in the area as economic development. The road is slightly sloping to steep over most of it. The total length was therefore divided into 25 'cells', each divided by control dams. These dams allow each cell to fill with water during an exceptional rainstorm and then flood over the top of the dam to the next cell. Instead of normal topsoil, a substrate is used to improve drainage. This consists of: - 70% crushed sandstone granulate, this promotes drainage and gives bulk and firmness to the substrate. - 20% composted green waste from Sheffield. The compost component is important because it contains a series of plant nutrients that are slowly released to the plants. Crucially, it retains water for plant growth, improves soil structure for proper root growth, and promotes soil microbiota - 10% sandy sludge. The standard soil-forming components of sand, silt and clay are essential to promote the availability of nutrients for plants and provide an optimal soil structure for plant growth. A mulch layer of 50 mm sandstone aggregate was spread over the constructed substrate. This allows natural degradation of pollutants (e.g. hydrocarbons). A wonderful example of inner-city greening!
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I know which one I'd prefer to live in!! Maintenance of green areas will create jobs too.