3.3.5 Impact Mitigation
Mitigation involves measures to avoid, reduce, remedy or compensate for the various impacts associated with projects (Glasson et al. 1994, CEC 1990). Whitney and Maclaren (1985) defined mitigation as the actions undertaken to ameliorate the negative impacts of a development. According to USCEQ (1978, 1987) mitigation includes the following.
1. Avoiding the impact altogether by not taking a certain action or parts of an action.
2. Minimising impacts by limiting the degree or magnitude of the action and its implementation.
3. Rectifying the impact by repairing, rehabilitating, or restoring the affected environment.
4. Reducing or eliminating the impact over time by preservation and maintenance operations during the life of the action; and,
5. Compensating for the impact by replacing or providing substitute resources or environments.

Usually impact mitigation studies follow the impact prediction and evaluation step in the EIA process. However, the mitigation measures may be targeted in association with the identification of potential impacts i.e., at the scoping stage itself (Canter 1996). Mitigation measures may, inter alia, include the following (Smith 1993):
1. Changes in design, in processes, of raw materials and/or in location.
2. Remedial measures.
3. The use of visual barriers to hide developments.
4. Compensation both in monetary and non-monetary terms.

Canter (1996) observed that the USCEQ (1978) definition of 'mitigation' suggested a sequential consideration - avoidance, followed by sizing, followed by rectifying, followed by preservation and maintenance followed by impact compensation. However, as has been repeatedly emphasised in this research study the criteria of environmental sustainability dictates that EIA should focus on impact compensation and not on impact minimisation. Avoidance of impacts should be the most desirable target.

3.3.6 Comparison of Alternatives
Alternative means of meeting the project objectives, including alternative sites are identified at the 'scoping' stage. The basic purpose of considering all the feasible alternatives is to ensure that no feasible approach involving alternative sites, scales, processes, layouts and operating conditions are left out so that an optimum decision can be arrived at. Alternatives should essentially include the 'no action' alternative. Subsequent components of EIA process identify the potential impacts and predict and evaluate the significant impacts due to all the alternatives under consideration. At the evaluation stage the positive and negative effects of each alternative are separately summed up either by preparing a short list of significant impacts indicating severity in terms of magnitude and importance or by aggregating the impacts by using a commensurate scale. It is advisable that after mitigation planning for each alternative is completed the evaluation score (where aggregation is contemplated) be re-estimated for each alternative. The re-estimated scores may now be used as a basis of decision making regarding whether or not to proceed with the development, and if so, which alternative should be adopted (Smith 1993, Ortolano 1984). At this stage the alternatives are compared essentially on the basis of the predominant impacts which are determined and interpreted carefully.

At various stages of the EIA process, information about a reasonable number of realistic alternatives should be 'distilled' into a format that will facilitate decision making (Glasson et al. 1994).

Over the years several techniques have been developed for evaluating and comparing the environmental consequences of alternatives. These techniques may often be useful tools in preferential ranking of alternatives indicating clearly the reasons for preferences. All or some of the following issues may be expected to be addressed by these techniques of alternative comparison (Smith and Theberge 1987, Smith 1993, Westman 1985).

1. Aggregation versus disaggregation of impacts.
2. The level of measurement to be employed.
3. Weighting procedures.
4. Possibility of using common measurement units.
5. Ease of understanding.
6. The number of alternatives to be evaluated.

Methodologies used for comparison of alternatives on the basis of environmental consequences varies from simple non-quantitative description to very high quantitative techniques involving translation of all impacts into a commensurate units. It should however, be borne in mind that many real benefits could accrue by direct exploitation of qualitative data. Quantification of a qualitative value does not allow a more accurate judgement, neither does it make the judgement more objective (Thompson 1990).

3.3.7 Documentation and Monitoring
The above paragraphs (3.4.1 to 3.4.6) have outlined the main stages of the EIA process and have established sequential linkages and complex interrelationship between the stages. The EIA study ends with preparation of report and it is this report that undergoes scrutiny by the appropriate impact assessment authority. If a project is approved the actual impacts must be monitored. A detailed analysis of monitoring at various phases of the project life is not within the purview of this study. It must however be recognised that monitoring reveals the effectiveness of mitigation measures and the correctness of impact prediction. EIA process components can be fine-tuned to a great extent through an appropriately designed scheme of impact monitoring.

Based on the above discussions the process of EIA can now be summarised as a series of interactive steps:
1. defining goals and short-listing the feasible alternatives to achieve the goals;
2. designing the selected project by clearly dividing the action into a finite number of activities and then designing each activity;
3. deciding whether an EIA is required for the project under consideration (screening);
4. identifying the impacts to be considered for the EIA study;
5. preparation of EIA: assessment of the magnitude and significance of environmental impacts to be caused by the proposed project and its various alternatives; and,
6. evaluating the adequacy of the EIA report and preparing appropriate mitigation plan.

Since the steps are inter-linked the EIA process should be regarded cyclical rather than linear.