Emphasizing Environmental Management and Monitoring - Mining and the Environment: From Ore to Metal - page 465

mistaken belief that ARD was not occurring, and the subsequent unpleasant surprise
when the buffering capacity was eventually overcome, as evidenced by a rapid decline
in pH. Monitoring of sulphate (SO 4 ) concentrations would have provided early warn-
ing that ARD was, in fact, occurring.
3. Cyanide also is readily decomposed by reactions with minerals in soil and rock, yield-
ing carbon and nitrogen oxides. The products of these reactions may not be identii ed
through a normal suite of parameters. Again, it is possible that the capacity for such
reactions will eventually be exceeded, at which time cyanide may be detected in moni-
toring bores.

Such situations are discussed in more detail by Mulvey (1997). In all these cases, it may be
several years or more before any direct evidence of groundwater contamination is identii ed.

Monitoring Locations

Monitoring locations are selected, based on statutory requirements and common sense. For
water quality monitoring, any compliance points identii ed in the EIA documents or in
government permit conditions represent the most important sampling locations. Similarly,
locations are selected to enable project-related contamination to be distinguished from con-
tamination that results from other causes. Therefore in the simple example of a project
producing a single efl uent discharge to a surface stream, monitoring points would be
located upstream of the discharge, at the efl uent source itself, and immediately down-
stream of the discharge. Depending on the regulatory situation, compliance points could be
at the efl uent discharge itself or at a prescribed distance downstream (selected to allow for
thorough mixing of the efl uent in the stream), or both. Since baseline data serve as a refer-
ence, monitoring locations are best linked, where possible, to sampling locations used in the
initial i eld surveys. This applies to physical, chemical, biological, and social parameters.
When monitoring of groundwater quality in the vicinity of tailings facilities, waste rock
dumps and other locations where there is potential for groundwater contamination, con-
sideration should be given to directions of groundwater l ow. In this respect, the inl uence
of the facility on groundwater l ow directions should also be taken into account. Clearly,
the majority of groundwater observation bores should be located down-gradient (in terms
of the water table) from the potential source of contamination.

Monitoring locations are best
linked, where possible, to
sampling locations used in the
initial fi eld surveys.

Monitoring Duration and Frequency

Monitoring should occur throughout the construction, operation, and de-commissioning
phases of the mine. The duration and frequency of monitoring should rel ect the nature of
the impact. Efl uent discharge often requires continuous monitoring during the entire mine
operation. In contrast, progress achieving net income goals for resettled people, a require-
ment in line with the imperative expressed in the World Bank's Involuntary Resettlement
Policy (OP 4.12), may be amenable to annual monitoring over a period of several years.
Attention should be given to seasonal and diurnal variability in designing monitoring pro-
grammes. This is clearly important in relation to aspects of climate, surface hydrology and
groundwater. However, it is also important for many biota, the presence or population of
which may differ markedly from one season to another, or in the case of marine zooplank-
ton - diurnally. The same considerations apply to the design of social surveys. For example,
door knocking with questionnaires will yield different population samples during the day

The duration and frequency of
monitoring should refl ect the
nature of impact.

Attention should be given to
seasonal and diurnal variability
in designing monitoring
programmes.