Identifying and Evaluating Impacts - Mining and the Environment: From Ore to Metal - page 446

Impacts and Risks

Even with a i nal project design and an unchanging environment, impacts are difi -
cult to predict with certainty. This is partly because impact prediction is always based on
judgement, even when impacts have been assessed using quantitative tools such as math-
ematical modelling. For example, uncertainties are introduced when selecting the math-
ematical model, determining input data, or when interpreting model outcomes. Partly,
this is because prediction is based on known or historical, but never certain information.
Uncertainty is inherent in all geological and geotechnical investigations because the expo-
sures and samples provided by techniques such as drilling represent but a tiny proportion
of the volume of soil or rock that is the subject of investigation. Partly again, this is also
because mine design is largely based on normal operating conditions although allowances
for 'upset conditions' and worst case scenarios are made. Finally, accidents do happen. For
example, the failure of tailings storage facilities continues to occur at mining operations
around the world, often associated with signii cant environmental damage including loss
of life. Other unplanned events are likely to occur - such as road accidents, landslides,
chemical/oil spills, i res, or explosions.
How should uncertainty be allowed for in the environmental assessment process?
Simple risk assessment tools help (US EPA 1998; EEA 2006).

Impact, Hazard and Risk: Problems with Terminology

In the context of an EIA, risk assessment is the evaluation of risks to the environment
based on an analysis of threats to, and vulnerabilities of mining operation and activi-
ties. One of the difi culties with the concept of both risk and impact alike is that risk and
impact relate to common experiences for which a language has been developed across
a diverse range of disciplines and activities. This language often lacks precision, and its
ambiguity can lead to confusion. The term risk assessment, as an example, may have a dif-
ferent meaning for the chemical engineer than it has for the biologist. The medical doctor
is concerned about health risks, where as the ecologist is concerned about ecological risk
and so on. Without being descriptive, the terms 'impact', 'hazard', and 'risk' used in this
text are dei ned as follows: (1) impact is dei ned as an environmental change caused by
the mining project (either positive or negative); (2) hazard is dei ned as a property (e.g.
mine water quality) or situation (e.g. storm event) that in particular circumstances could
lead to negative environmental impacts; and (3) risk is dei ned as the combination of the
probability (sometimes also termed frequency or likelihood) of occurrence of a dei ned
hazard and the magnitude of the consequences of the occurrence (that is the severity of
potential negative environmental impacts). A hazard can change predicted impacts (e.g.
a storm event, further increasing predicted water turbidity of mine runoff) or it can lead
to the creation of a new set of environmental impacts (e.g. as it the case of an acciden-
tal break in a fuel l ow line). Assessing risks to occupational health and safety is often
not part of the environmental assessment; it is a well established specialized discipline,
embedded in mine management rather than in the environmental impact assessment
process.
The following questions help to identify hazards: (1) What can go wrong?; (2) Are all
natural hazards identii ed?; (3) How likely is it that these hazards will occur?; (4) How
frequently and where will these hazards occur?; or (5) How much coni dence can be
placed in existing data and information? Operating experience is most important in pro-
viding answers to these questions.

The term risk assessment may
have a different meaning for the
chemical engineer than it has for
the biologist.