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close this bookConducting Environmental Impact Assessment in Developing Countries (UNU, 1999, 375 pages)
close this folder3. EIA process
close this folder3.4 EIA process in tiers
close this folder3.4.1 Screening
View the document(introduction...)
View the document3.4.1.1 Illustrations of screening


Screening is the decision whether or not to perform an EIA. In some cases, screening would help to decide which tier of the EIA process should be used, that is, IEE or a detailed EIA. In this example, the process of screening extends to scoping.

Screening criteria generally involve the specification of the location, type, and size of the project. In the case of some countries such as India, the size of the project is defined in terms of the economic investment undertaken. Some countries establish a list of types and sizes of projects that must always have an EIA. Others apply guidelines on a case-by-case basis.

Over a period of time, the following development activities justifying an environmental assessment have emerged from both approaches:

· large industrial and manufacturing plants;
· large construction projects - deep draught ports, highways, airports;
· water resources structures - dams, irrigation systems;
· electric power plants;
· mining and minerals processing;
· hazardous chemicals manufacture, handling, storage;
· sewerage and sewage treatment plants;
· municipal wastes and hazardous wastes;
· new human settlements;
· large-scale intensified forestry, fisheries, or agriculture;
· tourism facilities;
· military facilities;
· large-scale changes in land use.

Figure 3.2 Iterative nature of the EIA process

However, the importance of an environmental consequence may be out of proportion to the size of a project. For example, a rural road can make pristine forest land accessible, or a small tannery or metal plating shop can release hazardous amounts of toxic chemicals.

It is not a good idea to place a quantitative limit of some measure of project size below which no EIA is ever required. This might provide an unreviewable exemption that could be taken advantage of by unscrupulous developers. For example, in one country, hotels with less than 80 rooms did not require an EIA; as a result, 79-room units were constructed in large numbers and substantial environmental impacts occurred.

In the final analysis, common sense and discretion must be exercised in deciding whether a proposal triggers the need for an EIA. Some small projects may have more adverse effects than some larger projects and the "threshold'' value judgement must always be applied on a case-by-case basis.