Identifying and Evaluating Impacts - Mining and the Environment: From Ore to Metal - page 448

to some extent represent judgements on the basis of the knowledge and experience
available.
Descriptive ratings of hazard probability, illustrated in Table 9.11 , range from 'unlikely'
to 'will occur/high certainty'. In most risk situations it will be easier to estimate the prob-
ability of risk than to judge its consequences. In some situations, estimating the likelihood
of rainfall will be based on interpretation of historical records. Statistical analysis of rain
fall data to determine the design l ood is one example. In others estimates will be based on
operational experience, e.g. estimating the likelihood of equipment failure.
Descriptive ratings of risk consequences are illustrated in Table 9.12 ranging from 'insig-
nii cant' to 'catastrophic'. Evaluating consequences of a risk or, respectively, evaluating the
severity of negative environmental change, involves determining the broader implications
of a hazard considering all three dimensions of sustainability, that is considering ecological,

TABLE 9.11
Rating of Risk Likelihood

Descriptor Descriptive Rating

Unlikely Very rare

Not possible

Seldom Remotely possible

Not expected

Occasional See sporadically

Occurs as often as not

Will occur/high certainty Occurs often

Occurs continuously

TABLE 9.12
Example of Rating of Risk Consequences

Description Environment Dimension Social Dimension Financial Dimension Reputation

Considerations

Insignifi cant Limited damage to minimal

areas of low signifi cance

Limited social change in well
defi ned communities

Financial consequences
below US$ 50,000 (50 k)

Occasional local grievances

Moderate/Marginal Temporary impacts; localized,

reversible damage

Social change in host communities;
limited change in social cohesion

US$ 51 k to 500 k Limited negative press

coverage in local
newspapers

Critical Exceedance of regulatory

thresholds; loss of wild life

Social tensions; uncontrolled infl ux of
people; decline of public sanitation;
potential public health impacts

US$ 501 k to 2 m Frequent international news

coverage; International NGO
involvement; Community
actions/protests

Catastrophic Irreversible damage to sensitive

habitats

Social unrest; Loss of human life;
public health impacts

Above US$ 2 m Long-term international

reputation loss; Violent
community actions