Starting up; early stages - Introduction to Environmental Impact Assessment - page 120

Quantitative methods
Quantitative methods attempt to compare the relative importance of all impacts by
weighting, standardizing and aggregating them to produce a composite index. The best
known of these methods is the environmental evaluation system (EES), devised by the
Battelle Columbus Laboratories for the US Bureau of Land Reclamation to assess water
resource developments, highways, nuclear power plants and other projects (Dee et al.
1973). It consists of a checklist of 74 environmental, social and economic parameters that
may be affected by a proposal; these are shown in Figure 4.14. It assumes that these
parameters can be expressed numerically and that they represent an aspect of
environmental quality. For instance, the concentration of dissolved oxygen is a parameter
that represents an aspect of the quality of an aquatic environment. For each parameter,
functions were designed by experts to express environmental quality on a scale 0-1
(degraded-high quality). Two examples are shown in Figure 4.15. For instance, a stream
with more than 10 mg/l of dissolved oxygen is felt to have a high level of environmental
quality (1.0), whereas one with only 4 mg/l is felt to have an environmental quality of
only about 0.35. Impacts are measured in terms of the likely change in environmental
quality for each parameter. Two environmental quality scores are determined for each
parameter, one for the current state of the environment and one for the state predicted
once the project is in operation. If the post-development score is lower than the pre-
development score, the impact is negative, and vice versa. To enable impacts to be
compared directly, each parameter is
Figure 4.14 Framework for the
Battelle Environmental Evaluation
system. ( Source: Dee et al. 1973.)