EIA-REP-325d-12 _BB_ - 201.09.14.pdf - SAHRA

EIA-REP-325d-11
October 2012
13. DESCRIPTION OF ENVIRONMENTAL IMPACTS (Reg
31(2)(k))
13.1 Water resources
13.1.1 Impact on ground water levels
Table 19: Impacts on dewatering of the groundwater aquifer
Activity
Depletion of the underground aquifer
Lowering of ground water levels
Nature of the
impact
Dewatering during operational phase of the mine
Status -
Receiving
environment
Underground aquifer
Extent (footprint; site; regional; national; international) REGIONAL
Magnitude
Intensity (low; medium; high)
Duration (short; short-med; medium; long; permanent)
HIGH
LONG TERM
Probability (Improbable; possible; likely; highly likely; definite) DEFINITE
Weighting factor
(WF)
WF (low; low-medium; medium; medium-high; high) HIGH
Mitigation
Efficiency (ME)
ME (high; medium-high; medium; low-medium; low) LOW
Without (Extent + Intensity + Duration + Probability) x Weighting Factor
mitigation (3 + 5 + 4 + 5) x 5 = 85
Significance
(WOM)
With mitigation
(WM)
Medium
WOM x ME = WM
85 x 1.0= 85
Medium
Significance With
Mitigation (WM)
MEDIUM
Source of impact:
Opencast and underground coal mining operations on at the Usutu colliery site.
Description of impact:
Mining operations may lead to the dewatering of areas surrounding the main mining area during the operational
phase of the mine. The dewatering of areas surrounding the orebody may in turn lead to the influx of water into
the incline and areas below surface level, during the operational phases of the Usutu mining operation. Ground
water modelling was undertaken to determine the influx of water into the box cuts.
Significance:
The Significance of the impact is assessed as medium. Further modelling is required to refine the predictions.
Mitigations:
Lowering of groundwater levels during mining:
Since the drawdown or the groundwater levels during mining could influence some boreholers, the following
measures are recommended:
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