Greening Brownfield and Contaminated Sites
By Tony Hutchings and Andy Moffat, Forest Research
The sustainable restoration of brownfield and contaminated land to “create safe and healthy local environments with well-designed public and green space” (Sustainable Communities Plan, ODPM, 2003) poses technical and social challenges. Many derelict sites have a low intrinsic economic value and so do not attract investment from leading corporate redevelopers, yet the dereliction process notoriously leaves a legacy of contamination and physical substrate problems which are financially costly to remedy.
Current evidence suggests that woodland has a strong and positive part to play in the future development of contaminated land, but the use of trees for safe and effective reclamation must be based upon a site-specific risk-benefit assessment.
‘Open space’, including unrestored brownfield and contaminated land, has inherent multifunctionality and consequent value. Such value can be considered simplistically to consist of ecological and social elements. In contrast to greenfield sites, brownfield sites also notoriously hold chemical (contamination), physical (e.g. compaction), ecological (e.g. invasive species) and social liabilities. Successful restoration requires that site value and liabilities are fully ascertained and understood prior to remediation. To create integrated, multifunctional landscape, best practice methodologies must be developed and utilised with the support of the community to maintain and enhance ecological and social value whilst negating potential liabilities.
The restoration and development process of brownfield and contaminated land requires a complex interaction of technical expertise to ensure safe, sustainable, beneficial and multifunctional use. To be successful, engineers, landscape architects, planners, and practitioners must use a holistic approach to find complementary solutions to complex problems. Achieving sustainable remediation of contaminated sites is highly challenging because of the heterogeneous nature of ground conditions; identification of existing social, ecological and archaeological resources; contaminants present; potential multiple contamination pathways to receptors; community engagement and involvement; and ensuring appropriateness and sustainability of the restored landscape.
The Forestry Commission is working with its partners to ensure that effective mechanisms and structures are in place to overcome these challenges. One approach, which is already showing considerable potential, is that adopted by the Forestry Commission's Land Regeneration Unit (LRU) which was established in 1997. The LRU works with landowners and other stakeholders to restore brownfield land to a state fit for woodland to thrive, and can offer long-term Forestry Commission involvement in the management of the woodland for local community benefit. Forest Enterprise has already acquired over 200 hectares of former brownfield land in England, but the Forestry Commission is jointly responsible for restoration to modern standards of a much larger amount of land owned by local authorities and others.
Forestry Commission research into the restoration of disturbed land to woodland has been conducted since the early 1970s. This research has primarily addressed physical and nutritional problems on mineral workings, colliery spoils and former landfill sites. Comparatively few studies in the UK have considered the reclamation of land contaminated with heavy metals, organic compounds, nutrients and/or acid generating wastes to woodland. To address this shortfall, Forest Research (the research agency of the Forestry Commission) are conducting an extensive research programme in close collaboration with the Environment Agency, local authorities, other research institutes and industry.
Whilst it is clear that contaminated land provides a challenging environment for woodland establishment, we have demonstrated that vegetation can be successfully grown in soils contaminated with heavy metals. We are currently developing ecotoxicological assessment methods which will provide developers and foresters with a means of determining the suitability of contaminated land for woodland establishment. In addition, we are studying species choice, planting configurations, cultivation techniques and soil amendments that are likely to maximise the benefits of woodland planting for the stabilisation and remediation of contaminated land, whilst assessing the risk of contaminant mobilisation, and the public benefits woodland establishment brings.
For further information on any of the topics covered in this article please contact:
Contaminated land research
Forestry Commission Land Regeneration Unit
Department of the Environment, Transport and the Regions. (2000). DETR Circular 2/2000 Contaminated Land: Implementation of Part IIA of the Environmental Protection Act 1990. The Stationery Office, London.
Forestry Commission. (1999). England Forestry Strategy. A New Focus for England’s Woodlands. Strategic Priorities and Programmes. Forestry Commission, Cambridge.
ODPM. (2003). Sustainable Communities: Building for the future. ODPM, London.