Identifying and Evaluating Impacts - Mining and the Environment: From Ore to Metal - page 408

TABLE 9.4
Examples of Impact Scale Description Criteria - While objective approaches to identifying impacts and assigning
signifi cance attributes may exist, evaluating and ranking impact signifi cance will remain largely a subjective exercise

Negligible
●

Small localized impact

●

Low probability of occurrence

●

Impact is reversible

Minor
● Abnormal operating conditions would cause breach of legislation
●

Impact and probability of occurrence both small

●

Emissions are within statutory thresholds

Moderate
●

Moderate impact occurring over short period

●

Environment has time to recover

●

Project benefi ts are limited to few people

Signifi cant
● Project activity has an irreversible impact, but impact is moderate
● Project activity results in a breach of legislation under abnormal operating conditions
● Confl ict with established recreational, agricultural, or other established uses of the project area
● Effect and probability of occurrence are moderate
● Tailings dam exceeds 15 m in height (World Bank 2001b)
●

Project benefi ts entire community

Severe
● Impact is irreversible affecting a high number of people

● Impact causes resettlement of more than 500 households (ADB 1998)

● Impact exceeds legal thresholds

● Disrupts or adversely affects a property of cultural signifi cance to a community or ethnic or social group

● Project induces substantial growth or concentration of population

● Project converts prime agricultural land to nonagricultural use

Unacceptable (applies to negative impacts only)
●

High likelihood of catastrophic failure

●

Loss of life

●

Impact on nationally/internationally recognized environmental protection areas/heritage sites

9.3 DECIDING ON THE METHODOLOGY

There are as many methodologies to assess impacts as there are impacts. Before selecting a
specii c method, consideration should be given to acceptability, accuracy, relevance, coni -
dence limits, and proportionality of efforts
Is the method objective? Objectivity is a prerequisite for acceptability and credibility of
the environmental assessment. Objectivity diminishes the possibility that predictions auto-
matically support preconceived notions that are usually the result of self-interest, lack of

Objectivity is a prerequisite for
acceptability and credibility of
environmental assessment.