This study is focussed towards improving the science of EIA and it is therefore thought prudent to exclude the study of public input at the various EIA planning steps and public comment at the environmental decision making step of the EIA process.

As has been emphasised before, EIA studies can auger well with the goal of environmental sustainability if the focus is changed from impact minimisation to impact compensation. Under the conventional EIA studies mitigation measures are planned to reduce undesirable project effects. Public participation of mitigation planning often allows trade-off between long-term environmental damages and short-term socio-economic benefits, which evidently is environmentally unsustainable. The process of EIA should then consist of the following stages: -
1. Screening: Assessment of the need for an EIA. Whether there is any possibility of significant stress or shock on the supportive and assimilative capacity of the surrounding environment.
2. Scoping: Identification of issues and impacts to be considered in the EIA study.
3. Baseline study: Conducting necessary field studies for generating baseline data to define the pre-project environment.
4. Impact prediction and evaluation.
5. Mitigation planning: proposing necessary actions to reduce the severity of predicted adverse impacts and to make provision to compensate for any residual adverse impact.
6. Comparison of alternatives.
7. Decision making relative to the proposed action.
8. Study documentation: preparation of EIA report.

3.3.1 Screening
Under the new focus screening would be attempted to assess the desirability of conducting EIA study for the proposed or impending human activity. While nature, magnitude and significance of the likely impacts would be the prime considerations, the institutional arrangements and the legal framework for carrying out EIA cannot be altogether dismissed.

The principal objective of screening is to ensure that a full EIA study is conducted only for projects likely to have significant environmental impact. If the probable impacts of the project are not properly assessed it is preferable to subject the project to EIA study. Since this research desires to hinge EIA study on environmental sustainability, any project attempting to alter the supportive or assimilative capacity of the environment should be subjected to EIA study. This should be done irrespective of the fact whether such alterations would enhance or reduce the environmental carrying capacity. As has been emphasised before small projects may not individually be able to cause any major change in environmental carrying capacity. Such projects should be subjected to 'cumulative effects assessment' (CEA).

Requirement of a comprehensive EIA can be partly determined by the regulatory framework in a country. Categorical exclusion often allows many projects to go ahead without an EIA study. In the context of developing countries EIA is often required to be accomplished before obtaining financial support from donor agencies, viz., The World Bank, The Asian Development Bank, UK Overseas Development Agency, The United States Agency for International Development (USAID), etc. Provision for categorical exclusion is also found in EIA guidelines issued by the external funding agencies, e.g., the World Bank (World Bank 1991a). Where it is not explicit from regulation or agency guidelines whether an EIA is needed or not the following criteria may help deciding about the need for EIA (Glasson et al. 1994, Roe et al. 1995, Tomlinson 1984):-
1. Project scale.
2. Sensitiveness of the project site.
3. Expectations of adverse environmental change.

Under the proposed changes in the framework of EIA it is only logical that the criterion (3) be extended to include possible alteration in the natural capital stock. Local environmental setting and the scale and complexity of the project often are the decisive factor in the determination of the extent of EIA requirement. Following types of projects often require a comprehensive EIA (Roe et al. 1995, World Bank 1991a):-
1. Projects involving significant changes in natural resource utilisation,
2. Projects involving substantial changes in farming or fisheries practice,
3. Water resource projects including dams, irrigation, watershed development etc.,
4. Infrastructural projects,
5. Extractive industries, and
6. Waste management and disposal.

In case there is incomplete information about the possible environmental consequence of the proposed human activity, a preliminary study employing rapid environmental assessment technique may be undertaken.

Such a preliminary assessment should seek to answer the following questions.
1. What are the sensitive environmental attributes against the local environmental context?
2. What key impacts are likely to be caused by the proposed activity? What would be the likely magnitude and significance of such impacts?
3. How important are the likely impacts against the standpoint of decision making?

The procedure of preliminary or rapid environmental assessment incorporates many components of EIA process and is therefore often called an initial outline EIA or an Initial Environmental Evaluation (IEE). UNEP (1980) has developed a procedure on how to undertake an IEE (Figure 3.9). Preliminary identification of probable impacts includes a study of the relationship between the important project activities and the main environmental parameters. The likely interactions between the two are critically examined. A preliminary environmental appraisal is then conducted to ascertain the likely impacts of the project on the elements and sub-elements of the environment. Usually a questionnaire checklist is used and the answers to these questions provide a simplified view of the decision to be made as to whether an EIA is required (Tomlinson 1984). If no comprehensive EIA is required an IEE report (also called a rapid EIA report) may be prepared and project decision, - including selection of mitigative measures, may be taken based on the IEE report ascertaining 'finding of no significant impact' (FONSI). If the requirement of a comprehensive EIA is suggested at the screening stage (or at the rapid EIA stage) one of the first tasks of the interdisciplinary EIA study team should be to carry out scoping exercise.