In the UK a brownfield site is defined as “previously developed land” that has the potential for being redeveloped. It is often (but not always) land that has been used for industrial and commercial purposes and is now derelict and possibly contaminated. In the USA a brownfield site always refers to industrial land that has been abandoned and that is also contaminated with low levels of hazardous waste and pollutants.
The lack of available green spaces for development purposes has meant that brownfield sites have become increasingly popular in recent years, especially in places where demand for residential and commercial property is high. There are over 66,000 hectares of brownfield sites in England, and around a third of these are in the high-growth areas of greater London, the South East and East. The UK is committed to developing brownfield sites as a priority. It has already exceeded its 2008 target of building over 60% of new houses on brownfield sites, and aims to significantly grow this percentage over the next decade.
Brownfield sites are considered for redevelopment of not only housing and commercial buildings, but also as open spaces for recreation, conservation, woodland and other community areas.
All brownfield sites need to be assessed by an experienced environmental consultant before they can be redeveloped. This involves an analysis of the soil, groundwater and surface water through testing for hazardous compounds, and ensures that appropriate measures are taken to reduce identified risks and liabilities. Any development plans must be made compliant with current regulations. Special licenses are required to reclaim brownfield sites and strict environmental regulations can be prohibitive for developers. If the environmental assessment is positive and supports the redevelopment, the next step is remediation.
Remediation of a brownfield site is the removal of all known contaminants to levels considered safe for human health. Redevelopment can only take place after all environmental health risks have been assessed and removed. Remediation can be expensive and complex, and this needs to be seriously considered before purchasing brownfield land. Not all sites are deemed suitable for remediation, particularly if the costs exceed the value of the land after development.
In the last few years several new and exciting remediation technologies have started to emerge. These are proving to be relatively low-cost compared to traditional processes, with the benefit of protecting and preserving the environment:
- Bioremediation uses the natural processes of indigenous bacteria, microorganisms, plants, enzymes and fungi to destroy or neutralise toxins and contaminants.
- Phytoremediation uses plants to store contaminants in their leaves and stems (bioaccumulation). Some contaminants such as heavy metals can be harvested and mined for reuse (phytomining). With phytoremediation, it is critical that contaminants do not enter the food chain. With this in mind, scientists are currently exploring the value of biofuel and energy crops as phytoremediators.
- In-Situ Chemical Oxidation injects oxygen or chemical oxidants into the contaminated soil or water to destroy harmful compounds.
These new remediation technologies are providing important information about the abilities of natural processes to transform poisonous materials back into a harmless state. This information has widespread application in many situations, but is particularly relevant for restoration of the damaged environment and rehabilitation of brownfield land.
The reclamation and reuse of brownfield sites is a core component of the UK Sustainable Development Strategy integrating a wide range of economic, social and environmental objectives. Brownfield redevelopment not only cleans up environmental health hazards and eyesores, but it is also a catalyst for community regeneration, particularly when communities are brought into the consultation process of site identification and restoration. Managed effectively as a sustainable redevelopment scheme, brownfield sites provide affordable housing, create opportunities for employment, promote conservation and wildlife, and offer a shared place for play and enjoyment. Above all, the transformation of a brownfield site is a vision of hope for the future.