Identifying and Evaluating Impacts - Mining and the Environment: From Ore to Metal - page 402

TABLE 9.2
Categorizing Environmental Impacts - Since an environmental impact is independent of its categorization, categorizing impacts is a tool, not an end

Direct (or primary)
Impact that results from the direct interaction between project activity and receiving environment (such as between effl uent discharge and receiving water
quality).

Indirect (or secondary)
Impact that follows from primary interactions between a project activity and its environment as a result of subsequent interactions within the environment
(such as soil loss as a consequence of land clearing affecting down stream aquatic habitats).

Cumulative
Impacts acting together to affect a particular environmental resource or receptor. Several types of cumulative impacts are defi ned in the literature.
Temporal: a series of impacts, in themselves not insignifi cant, occurring repetitively to build up to the point that they become signifi cant (such as family
stress developing due to a fl y in/fl y out working arrangement).
Accumulative: the overall effect of different types of impact (such as air pollution and noise and traffi c and visual blight) on a single receptor (such as a
community or a habitat) where each single impact may not be signifi cant, but combined they are.
Additive: where impact from the planned activity occurs at the same time as impact from activities being undertaken by other parties.
Interactive: where two different types of impact (which may not in themselves be signifi cant, say overburden placement and increased infi ltration) react
with each other to create a new impact (that might be signifi cant such as acid rock drainage).
Synergistic: where two impacts interact together (e.g. changes in water quality with respect to two different pollutants) to create an impact that is greater
then the sum of their parts.

Induced
Impact originating from other developments or activities that are encouraged to happen as a consequence of the original development (such as the mine
development stimulates a requirement for improved site access leading to an increase in local population).

Non-Normal (or accidental)
Impact that results from un-planned events - incidents - within the project (such as breakdowns, failures, or human error) or in the external environment
affecting the project (such as fl oods, seismic activity, or landslides). The probability (or likelihood) of the event becomes important.

Source:
Based on SHELL (2003)

FIGURE 9.2
Categorizing Impacts

Direct impacts
IMPACT A

Indirect impacts
IMPACT C

Activity one

Direct project impacts are usually pre-
dictable with certainty while indirect
impacts are often subtle and diffi cult to
identify and measure.
Source:
Based on Walker and Johnson 1999

IMPACT B
(Cumulative)

IMPACT D
(Interactive)

Activity two

Direct impacts are dei ned as environmental changes directly associated with project
activities ( Figure 9.2 ). In mining, examples include change of topography, erosion, dust
emissions, or change of water quality due to efl uent discharge. Direct project impacts are
usually predictable with certainty.
Indirect impacts are dei ned as environmental changes not directly associated with
project activities, often occurring at a distance from the mine, and as a result of complex
pathways. Indirect impacts are referred to as second or third level impacts, or secondary