Sustainability and Remediation - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 920

regard to social impacts, with particular stakeholders may be interested in distin-
guishing short and long term effects. The duration boundaries are essentially the
time classifications used to draw these distinctions. An important aspect of the
time boundary for assessments using moneterisation is the discount rate that will
be applied in net-present value calculations.
20.3.4 Techniques and Tools and Their Applicability
Table 20.1 listed a range of techniques that have been applied to sustainability
appraisal, or aspects of sustainability appraisal, or have potential to be used in sus-
tainability appraisal. This section reviews them each in more detail. None of the
techniques used in sustainability appraisal is an absolute valuation. All are funda-
mentally flawed in that they can only assess what we know or perceive may be an
issue. For example, would a contemporary sustainability appraisal of DDT in the
1930s, if such a thing existed, have taken into account its impacts on birds of prey,
as biomagnification was not a known phenomenon at that time.
20.3.4.1 Systems Using Scores, Rankings, Weightings, Including
Multi-Criteria Analysis
Many techniques that are qualitative, such as cost effectiveness analysis, use scores
(some kind of figurative effort of the scale of an effect) and often also use weightings
(some kind of figurative effort of the relative importance of an effect). Weightings
and scores are typically combined, scaled and otherwise arithmetically processed,
for example using Multi-Criteria Analysis (see Box 20.1 ). This may yield a result
that appears rather definitive, perhaps more definitive than should be inferred from
the original process of scoring and weighting since there are several limitations in
using scores and weightings.
Types of scoring might include symbols like ++, +, 0, -, --; or numeric values
such as scores from 1 to 10 or 1 to 100%. A fundamental limitation is that this scor-
ing will always be subjective, unless it includes an element of formal quantification.
Where scores are determined on the basis of best guess there is no way to guarantee
that one person's “++” is not the same as another person's “+”, setting aside any dif-
ferences in stakeholder perspective, but purely because some people tend to score
high and others low. What is particularly problematic about scores is that they add
a “numeric” gloss, i.e. the illusion that something is known in a quantitative way
when it is not. These apparent numbers can be manipulated and processed, perhaps
to the extent where their original unreliability may be forgotten. Scoring can take a
lot of time for not much added value, for example, as they wrestle with questions
like: “should a score be 65% or 70%?” Weightings are always by their intrinsic
nature subjective, as different stakeholders can weight differently according to dif-
ferent perceptions of importance. Deciding weightings can add complication and
contentiousness to the appraisal process, and they are in effect a valuation without
formal derivation.