Forgemasters - combining SUDS in landscape design

Sheffield Forgemasters' steel works was an unlikely location to create a visionary habitat rich in biodiversity. The goal was to use sustainable urban drainage design to prevent flooding, while providing a rich habitat for wildlife, but before planting could begin work needed to be done to engineer a fit for purpose growing medium.

Background

The addition of compost to degraded and compacted soils has the potential to contribute to improved structure and, therefore, a richer soil environment. Its ability to support vegetation – which in turn provides ground cover – protects the surface of the soil against erosion, while the microbial and earthworm activity that flourishes in rich compost systems provides a range of benefits, from improved structure to the creation of stable soil spaces that enable improved moisture percolation.

As a result, when the world's largest independent forgemaster, Sheffield Forgemasters International Ltd (SFIL), decided to create a biodiversity rich amenity area on the site of an old furnace where soil resources were limited to excavated demolition material and subsoil, BSI PAS 100 compost became an integral part of the site design.

UK Biodiversity Action Plan 

The one-acre area earmarked for the project is part of the Forgemasters Works. The aim was to create a UK Biodiversity Action Plan (BAP) priority species and habitat to encourage wildlife, and to offer staff a rich environment to enjoy. In addition, non-woodland areas were planted with high profile species such as wildflowers. Before planting, a layer of surplus subsoil from another area of the works was applied to the site, followed by a blended layer of subsoil and compost at a ratio of 2:1 and depth of 900mm. The compost was sourced from local producer Green Estates in Sheffield and proved beneficial, not only in adding nutrients and organic matter, but also in increasing the water holding capacity of the soil. This is particularly beneficial when designing a flood alleviation zone such as this.

The wildflower planting proved particularly productive, showcasing a magnificent display of colour and species diversity that flowered over a long period and is likely to encourage a wide range of birds and associated wildlife onto the site.

A variety of environmental circumstances impacted on the woodland area. Of the tree species planted, blackthorn, hawthorn, pear and sweet chestnut responded most positively, while beech and Scots Pine struggled to establish.

This was due to factors such as poor drainage and waterlogging. It is likely that a more extensive use of compost could have reduced some of these factors, while significantly better preparation of the site could be used to alleviate inadequate drainage beneath the soils.

The result

In spite of the problems encountered by some species, those that successfully established showed rapid circumference and height gain, boasting measurements at the top of the range. This clearly demonstrates that the addition of compost has a beneficial effect and aids the acceleration of new growth.

Vicky Hinchcliffe, Group Environment Manager at Sheffield Forgemasters concluded: "The creation of the Forge Garden has been hugely valuable in helping us to introduce biodiversity corridors through predominantly industrial areas. We get great feedback from clients touring the facilities who find it an unexpected delight to find this garden in the midst of the industrial feel of the plant, and it has also become a valuable resource for employees, who now have somewhere to enjoy their breaks away from the industrial processes."