Environmental Engineering Reference
In-Depth Information
compared to the evenings. Similarly, in traditional agricultural societies, surveys during the
planting and harvesting periods would result in an extremely non-representative sample.
Sometimes it is necessary to experiment in order to select the most cost-effective sam-
pling frequency. For example, measurement of groundwater levels may be made weekly
or even daily at i rst, until the rate and magnitude of change become clear. Then it may be
possible to reduce the frequency to monthly or quarterly, and still identify maximum and
minimum levels.
In the absence of any compelling or statutory requirements, monthly sampling is usually
selected for water quality analyses other than for efl uent discharges, which may be moni-
tored continuously or hourly as is commonly the case for cyanide, or daily for other param-
eters of concern. Biological monitoring is usually conducted annually, twice per year or four
times per year, depending on which parameters are being monitored and the seasonal vari-
ations that apply, as revealed by the baseline surveys. Monitoring of rehabilitation success
is generally conducted annually, usually near the end of the wet season, although there are
benei ts in conducting a second round of monitoring towards the end of the dry season.
Environmental Monitoring Plans are Living Documents
As is the case for environmental management plans, environmental monitoring plans are
living documents. Monitoring locations may change with changes in mine development;
monitoring results may suggest to delete (or to add) selected parameters, or to adjust mon-
itoring frequency. As one example, there is little benei t in monitoring groundwater qual-
ity monthly if past track records demonstrate only small variations over time.
The dynamic nature of environmental monitoring plans (and management plans as well)
is illustrated in Figure 10.4 . The design of monitoring is shaped by the monitoring objec-
tives. The objectives in turn are inl uenced by the outcome of monitoring results.
Because the natural environment changes with time, it is not always easy to distinguish
incremental project-induced changes. But in order to understand environmental changes
due to mining, it is necessary to know what environmental conditions would have been if
mine development had not taken place. Hence it is important to include reference loca-
tions in the environmental monitoring programme, which will remain unaffected by mine
development. For water quality monitoring these are normally monitoring locations in
adjacent watersheds or upstream of the mine area.
FIGURE 10.4
The 'Plan-Do-Assess-Adjust'
Management Cycle
Strategize
Prioritize
ADJUST
PLAN
All management and monitoring sys-
tems consist of a cycle 'plan, do, assess,
and adjust' process that takes learning
and experiences from one cycle and
uses them to improve and adjust
expectations during the next cycle.
Commit
Interpret
Design
Analyze
ASSESS
DO
Measure
Test
 
 
Search WWH ::




Custom Search