Under the relevant European Directives, an Environmental Statement is the formal product of an Environmental Impact Assessment. Environmental Statements are often organised in a way that describes the environmental baseline, mitigation and effects for each type of environmental receptors: ecology, water resources, archaeological resources, human beings etcetera. Contaminated land is often managed in the same ways as the various environmental receptor groups, although it is principally a cause of impacts rather than a receptor. It also often refers to a pre-existing condition and its damaging effect is on a variety of different receptors such as human health, structures and buildings, surface water features, groundwater features and ecology. This often means that land contamination specialists struggle with integrating the issue in a logical manner in an Environmental Statement. Sticking to the structured approach of an environmental statement is essential to ensure a clear description of the existing environmental condition, the potential impacts and the actions taken to avoid, minimise, offset or manage the impacts. This article is based on UK practice and legislation, although fundamentally the issues should be similar within other contexts.
Contaminated land is in many countries considered on a source-pathway-receptor basis. This is important to understand the impact land development can have on the issue of contaminated land. Development can interfere with any of these three elements. It can introduce sensitive receptors by changing the use of land, for instance by building new residential units on a site that was previously used for heavy industry. New pathways linking pre-existing contamination with an existing receptor can be formed, for instance when piling through a non-permeable layer connecting a layer of contaminated soils with a deep aquifer. Finally by introducing pollutants on the site a development project can introduce a potential source of contamination.
The second element to consider is the structured approach of an environmental statement. Apart from the introductory and procedural elements described in the environmental statement, a good environmental statement comprised the following sections:
- environmental baseline conditions
- potential environmental impacts
- mitigating measures
- residual environmental impacts
There should be a logical relation between the different sections. Any receptor that is affected and described in the section about the potential impacts and effects should have been introduced in the section describing the baseline. Any material impact should be assigned a mitigation or management action etc. Implementing this structure allows a clear description and understanding of the environmental impacts and the way it will be managed.
Applying these principles to contaminated land will result in a baseline condition section that describes the current sensitive receptors that are present within the potential sphere of influence of the development, the sensitivity and importance of these receptors, the presence of any pre-existing contamination and the presence of actual and potential pathways. The next section, potential environmental impacts or effects, first considers the impacts that the development will have in terms of the introduction (or removal) of sensitive receptors and the creation of new pathways between existing and potential pollution sources and receptors. In addition this section will describe the potential environmental impacts that are associated with the introduction of new sources of contamination. In the third section, mitigating measures, a description of the actions to mitigate each of the impacts that may occur should be provided. Finally a statement of the residual impact of the development is provided in the last section: residual environmental impacts.
Paul Giesberg is an environmental consultant with a special interest in environmental impact assessment and sustainability in land use development. |  |
