Improving urban environments

Green and blue infrastructure (in the urban context) is the environment within and between built up areas of cities, towns and villages and creating links to the countryside. It can include parks and gardens, trees, woodland and farmland, road and rail corridors and other green open spaces (green) and rivers, canals, lakes, and even ditches (blue). This urban infrastructure network, often incorporating PDL, provides space for the natural environment to continue to thrive in the built environment. Networks of green and blue infrastructure increase in their ecological value the wider and more joined up the networks are. In creating open space on PDL, there will be value in seeking to identify how to link into existing and emerging networks for open space.

Integrating water features into open spaces will create attractive environments and contribute to creating a sense of place.  The opportunity to create sustainable drainage systems (SuDS) will make open space a valued asset in terms of managing surface water and helping to prevent flooding.

In addition, sites may have a considerable amount of inert building rubble and waste vegetation present, above and below ground.  These can be re-used for establishing a new landscape of activity and amenity including for example creating walls, pathways and play equipment.

Creating an open space project will make a direct contribution to changing and ideally enhancing the local landscape character of an area.  The aim should be to identify if it is possible to retain a current shape of the landscape and recognise the site’s history whilst creating an area of value.

Case Study: Cronton Colliery restoration

The former Cronton Colliery site is located in the Borough of Knowsley in Merseyside where mining ceased in the early 1980s.

Early restoration saw the creation of two development plateaux and substantial woodland planting. The site was then acquired by English Partnerships and transferred to the North West Development Agency, who oversaw further phases of restoration, funded through English Partnerships National Coalfields Programme, including works to the watercourse and the removal of a redundant reservoir and lagoons.

As original ambitions to develop the site for hard-end use proved unsuccessful, an alternative Masterplan to develop the site as an informal country park was developed and agreed by key partners (the Land Restoration Trust, English Partnerships, the North West Development Agency, Knowsley MBC and the Forestry Commission) in 2006. Planning permission to develop the site as an informal country park was granted in May 2008.

The rationale for the project was based on observation of the site, where it appeared that former bare areas of spoil had re-vegetated and had developed an attractive semi-natural character which the Trust did not want to destroy.

The aim was to replicate this process on a more scientific basis, using PAS 100 green compost incorporated within the spoil surface to ameliorate spoil conditions sufficiently to establish a wildflower grassland sward on a permanent basis. One of the challenges was to add the appropriate quantity of green compost to allow the establishment of a permanent sward without encouraging the growth of pernicious weeds.

To date, the results appear to demonstrate that PAS 100 green compost can be used successfully to establish semi-natural grassland on bare colliery spoil, essentially by ameliorating its otherwise hostile chemical conditions. The green compost was the critical additional factor that explained the difference between the areas that established successfully and those that failed to establish.

The trials also demonstrated that this is an extremely cost effective approach. To import sub-soil and spread to a depth of 150mm would cost approximately £2.25 per square metre or £22,500 per hectare using a conventional approach. In contrast, importing PAS 100 compost, spreading to 30mm depth and incorporating it within the top 120mm of spoil cost £0.28 per square metre or £2,800 per hectare, a saving of approximately 88%. In addition, it made use of a recycled, local source of material, and kept disruption to the site and to local people to a minimum.