Case-by-case screening is carried out when the significance of the potential environmental impact of a proposal is unclear or uncertain. This process typically applies to proposals that fall just below or close to the thresholds established for listed projects. In addition, non-borderline proposals may be subject to screening if they are located in sensitive areas or there is a potential for cumulative effects in combination with other current and foreseeable activities. The framework outlined in figure 4-1 on page 4-2 of this course contains a sieve of screening applications with a progressively finer mesh for including proposals. It has gained a degree of international acceptance as a standard of good practice. The specific criteria for case-by-case screening differ from country to country. Typically, however, they are based on a number of common factors related to the consideration of the significance of environmental impacts. These include the location of proposals, environmental sensitivity and any likely health and social effects on the local population. In this context, reference may be made to the screening criteria listed in the European Directive, which apply to the selection of listed projects for which EIA is not mandatory. These criteria may be adapted to wider use in case-by-case screening. A proposal can be tested for significance by taking account of:
- location near to protected or designated areas or within landscapes of special heritage value;
- existing land use(s) and commitments;
- the relative abundance, quality and regenerative capacity of natural resources;
- the absorption capacity of the natural environment, paying particular attention to wetlands, coastal zones, mountain and forest areas; and
- areas in which the environmental quality standards laid down in law have been exceeded already.
Using the emphasised aspects above, consideration can be given to sustainability criteria when carrying out case-by-case screening. However, this approach demands considerable information about the environment, which is unlikely to be available at a relatively early stage in project development. In these circumstances, only a qualified determination of the environmental significance of a proposal may be possible and screening decisions must be open to change if new information indicates the advisability of reclassification. (One means of doing so is to incorporate a â€˜bump-upâ€™ or â€˜bump-downâ€™ provision into the screening procedure.)
Certain proposals may be subject to an extended screening or initial assessment (also called a preliminary EIA). Such an approach can be used when the requirement for EIA could not be reasonably determined by the application of the screening procedures described previously; for example when a proposal involves use of a new technology or is located in an near natural or frontier area or involves discharges into a water body that may exceed health or environmental standards. Often, this process, itself, may be sufficient to complete the requirement for EIA established by a particular country. In this case, a screening report should describe the results and identify any mitigation measures or actions that need to be taken.
When undertaking this type of preliminary EIA study, the proponent or competent authority may need to assemble considerable information. A checklist of the types of information that could be relevant for such a study are summarised below. This is accompanied by a framework of criteria and questions that can help in the conduct of a preliminary EIA (see Screening Criteria in the EIA Wiki). It is based upon Australian and New Zealand EIA practice and provides a detailed procedure for undertaking an extended screening or initial assessment. As and where necessary, it could be adapted to wider application in conjunction with the methods described below.
Information that may be required for a preliminary EIA study includes:
- a description of the proposal;
- applicable policies, plans and regulations, including environmental standards and objectives;
- the characteristics of the environment, including land use, significant resources, critical ecological functions, pollution and emission levels etc.;
- the potential impacts of the proposal and their likely significance;
- the degree of public concern and interest about the proposal.