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close this bookConducting Environmental Impact Assessment in Developing Countries (United Nations University, 1999, 375 p.)
close this folder3. EIA process
close this folder3.4 EIA process in tiers
close this folder3.4.4 The detailed EIA study
View the document(introduction...)
View the document3.4.4.1 Prediction
View the document3.4.4.2 Assessment
View the document3.4.4.3 Mitigation
View the document3.4.4.4 Evaluation


In the EIA process up to this stage, scoping identifies the significant environmental issues emerging from the project, while through the activity of IEE a preliminary study of the assessment of the various impacts is conducted. In addition, obvious mitigation measures are identified to meet regulatory requirements and any residual issues requiring further detailed study are identified.

The next tier involves detailed EIA. The study is broadly conducted along the lines of IEE, albeit in a more detailed manner. In the detailed EIA, all significant issues are examined once again in the formal framework of identification, prediction, and assessment, and all issues previously dealt in the IEE level are reassessed for adequacy. New issues, if any, are identified because of: (a) increased understanding of issues due to IEE; (b) project modifications; and (c) suggested mitigation measures.

An IEE often leads to either new information on the projects and its activities or the presence of a critical environmental component. This can lead to issues not identified earlier. For example, an IEE may focus on the normal emissions arising out of the stacks or well identified sources from an industry. However, additional information collected on the fill-and-draw of the storage tanks and emissions thereof, and properties of the chemical stored, can lead one to check the transient emissions as well. Similarly, possibilities of frequent start up and shut down of the plant (either due to process instability in the initial periods or due to power failure) may become a reason to include emergency or incidental emissions as an issue.

An exercise of IEE may ask for project modifications. These modifications would then need a scoping exercise (note the iterative nature of EIA) and in this process new significant issues may be identified.

In some cases, the mitigation measures themselves may require checks and balances as these are generally proposed in isolation at the IEE level. For example, for the mitigation of dust-laden emissions from an industry, a Venturi scrubber may be suggested. It becomes necessary then to ensure that the water (solvent) required for the purpose of scrubbing is shown in the overall water balance and that the scrubbed water is included in the overall effluent volume.

In the case of an industry discharging its effluents on a coastal area, an outfall into the sea may be suggested as mitigation. This measure can, however, lead to impacts during construction (e.g., noise and debris leading to disturbance to the marine ecosystem) as well as during operation (e.g., causing obstruction in the navigation pathways of the local fishermen). These issues arising out of the mitigations themselves need to be addressed in detailed EIA.

In detailed EIA, a systems approach is used in the identification of the significant issues.

The next step in detailed EIA is to classify issues which can be understood by available information and those which require additional information and inference. This leads to identification of the necessary surveys, prediction and assessment exercises, and appropriate mitigation measures. The final recommendations in the detailed EIA extend beyond the mitigation measures to include the necessary institutional set up for the support of the overall environmental management system.

It is possible that a few issues may be significant but not fully mitigable or only partially understood. These issues need to be communicated at the end of the detailed EIA through public information and consultation (PIC).

The essence and spirit of the exercises of prediction, assessment, and mitigation are described below in more detail. Prediction

As far possible, prediction scientifically characterizes the impact's causes and effects, and its secondary and synergistic consequences for the environment and the local community. Prediction follows an activity-component relationship (e.g., discharge of liquid effluent as an activity and river water quality as an environmental component) and estimates the subsequent effects (e.g., such as reduced concentration of dissolved oxygen, reduced fisheries). Prediction draws on physical, biological, socio-economic, and anthropological data and techniques. In quantifying impacts, it may employ mathematical models, photomontages, physical models, sociocultural models, economic models, experiments, or expert judgements.

To prevent unnecessary expense, the sophistication of the prediction methods used should be kept in proportion to the "scope'' of the EIA. For instance, a detailed mathematical model of atmospheric dispersion should not be used if only a small amount of relatively harmless pollutant is emitted. Simpler models are available and are sufficient for the purpose. Also, it is unnecessary to undertake expensive analysis if they are not required by the decision makers for whom the EIA is being done.

All prediction techniques, by their nature, involve some degree of uncertainty. So, along with each attempt to quantify an impact, the study team should also quantify the prediction's uncertainty in terms of probabilities of "margins of error''.

A shortcoming of many detailed EIAs is that social and cultural impacts are not given the prominence they deserve in describing the extent of changes expected to result from a major development project. This has probably been due to the bias of physical and biological scientists against the comparatively younger disciplines of cultural anthropology and sociology. This is an unfortunate bias, since sociocultural impacts are the ones that would affect the local community in their everyday lives. A consideration of sociocultural impacts should be integrated, wherever possible, into every discussion of physical/biological change, and not just treated separately in a minor chapter or appendix. Several methods and analytical tools are available for this purpose; they are discussed in detail in Chapters 4 and 5. Assessment

The next question addressed by the EIA - "Do the changes matter?'' - is answered in the next step, assessment, so called because it evaluates the predicted adverse impacts to determine whether they are significant enough to need mitigation. This judgement of significance can be based on one or more of the following:

• comparison with laws, regulations, or accepted standards;
• consultation with the relevant decision makers;
• reference to pre-set criteria such as protected sites, features, or species;
• consistency with government policy objectives;
• acceptability to the local community or the general public. Mitigation

If the answer to the previous question is "Yes, the changes do matter'', then the EIA answers the fourth question - "What can be done about them?''. In this phase, the study team formally analyses mitigation. A wide range of measures are proposed to prevent, reduce, remedy, or compensate each of the adverse impacts evaluated as significant. Possible mitigation measures include:

• changing project sites, routes, processes, raw materials, operating methods, waste disposal routes or locations, or engineering designs;

• introducing pollution controls, monitoring, phased implementation, landscaping, personnel training, involving social services or public education;

• offering (as compensation) restoration of damaged resources, money to affected persons, concessions on other issues, or fit site programmes to enhance some other aspects of the environment or quality of life for the community.

Note that some mitigations have already been identified in the IEE exercise.

All mitigation measures have a cost, and this cost must be quantified. Evaluation

At the end of the exercise of detailed EIA, an evaluation is performed considering all the project costs (including mitigation, compensatory, and enhancement measures) and project benefits (including no interruption due to compliance to regulations) to establish an overall cost-effectiveness of the modified project.