Impact prediction, evaluation and mitigation - Introduction to Environmental Impact Assessment - page 133

15. Effects on coastal or estuarine hydrology.
16. Effects of pollutants, waste, etc. on water quality.
Effects on air and climate
17. Level and concentration of chemical emissions and their environmental effects.
18. Particulate matter.
19. Offensive odours.
20. Any other climatic effects.
Other indirect and secondary effects associated with the project
21. Effects from traffic (road, rail, air, water) related to the development.
22. Effects arising from the extraction and consumption of material, water, energy or other,
resources by the development.
23. Effects of other development associated with the project, e.g. new roads, sewers, housing power
lines, pipelines, telecommunications, etc.
24. Effects of association of the development with other existing or proposed development.
25. Secondary effects resulting from the interaction of separate direct effects listed above.
( Sources: DETR 2000, ODPM 2003.)
of socio-economic impacts. Table 1.3 provides a broader view of the scope of the
environment, and of the environmental receptors that may be affected by a project.
Prediction involves the identification of potential change in indicators of such
environment receptors. Scoping will have identified the broad categories of impact in
relation to the project under consideration. If a particular environmental indicator (e.g.
SO 2 levels in the air) revealed an increasing problem in an area, irrespective of the project
or action (e.g. a power station), this should be predicted forwards as the baseline for this
particular indicator. These indicators need to be disaggregated and specified to provide
variables that are measurable and relevant. For example, an economic impact could be
progressively specified as
direct employment→local employment→local skilled employment
In this way, a list of significant impact indicators of policy relevance can be developed.
An important distinction is often made between the prediction of the likely magnitude
(i.e. size) and the significance (i.e. the importance for decision-making) of the impacts.
Magnitude does not always equate with significance. For example, a large increase in one
pollutant may still result in an outcome within generally accepted standards in a “robust
environment”, whereas a small increase in another may take it above the applicable
standards in a “sensitive environment” (Figure 5.1). In terms of the Sassaman checklist
(see Figure 4.8), the latter is crossing the threshold of concern and the former is not. This
also highlights the distinction between objective and subjective approaches. The
prediction of the magnitude of an impact should be an objective exercise, although it is