Identifying and Evaluating Impacts - Mining and the Environment: From Ore to Metal - page 410

Is the method selective? Often a method is preferred that focuses attention on the most
relevant environmental effects. It is often desirable to eliminate unimportant impacts
as early possible so they do not dissipate efforts during the detailed impact analysis.
Screening, to some degree, requires a tentative predetermination of impact signii cance,
and this may create subsequent bias. Impact assessment, however, could start with the
most critical environmental concerns by formulating initial sets of impact indicators and
environmental effects.
This limited set may be analyzed, at least in part, with relatively low expenditure of
resources. Analyzing only a few project impacts initially will create an appreciation, even
at this preliminary stage, of the factors that are likely to be important, and those that are
not. As the impact assessment progresses, impact analyses will become increasingly com-
plex. The assessment will expand naturally as time, money, and allocated human resources
permit.
Does the method estimate coni dence limits? Subjective approaches to uncertainty are
common in quite a few methods and can lead to useful impact prediction. Of course, sub-
jective methods are generally more acceptable, if assumptions are open to critical review
and, if desirable, alteration. In statistical methods standard deviation serves as measure
of uncertainty. Besides representing the coni dence limits, the standard deviation allows
one also to consider the most likely and the least likely effect (e.g. two standard deviations
from the mean). A large variation in both effects may indicate the need for further studies
and/or extended monitoring. The ramii cations of environmental uncertainty are consid-
ered in more detail in a later section of this chapter.
Does the method predict impact interactions? Environmental processes generally con-
tain feedback mechanisms. A change in the magnitude of an environmental effect may
produce unsuspected amplii cation or dampening in other parts of the environment.
Consider populations of most large wild animals which do not increase exponentially even
during the most favourable environmental conditions, due to a number of negative feed-
backs such as diminishing food supplies. Methods to analyze impacts should therefore be
capable of identifying impact interactions and estimating their magnitudes.
Is effort proportional to investigated effect? More often than not a method is selected
that is either too simple to accurately assess environmental change, or too complex for a
given impact. Overly simple methods do not work, since impact predictions will be neither
accurate nor accepted. Overly complex methods are equally undesirable. There is little
benei t in allocating substantial resources to analyzing minor effects ( Case 9.4 ). These can
best be dealt with using the judgements of experienced professionals.

It is often desirable to eliminate
unimportant impacts as early
possible so they do not dissipate
efforts during the detailed impact
analysis.

There is little benefi t in allocating
substantial resources to analyzing
minor effects.

9.4 LINKING CAUSE AND EFFECT

In the context of the following discussion, source is dei ned as the origin of an environ-
mental impact. It is an activity that imposes change to the receiving environment. A cause

CASE 9.4
Over-complexity or not?

The BP Tangguh LNG Project in Papua, East Indonesia
spent hundreds of thousands of US dollars on consultants
to advise on forest clearing for the construction camp and

the plant site. Direct impacts, with or without these expen-
ditures remain the same - a cleared forest area. Could
the money have been better spent on actual community

development programmes or on reafforestation programmes
elsewhere?