NKOMATI ANTHRACITE (PTY) LIMITED - Sentula Mining

Environmental Impact Assessment Report: Nkomati Anthracite (Pty) Limited,
Madadeni Opencast Mining Project Page 27
3.1.9 G r o u n d w a t e r
Since mining activities can potentially impact on the groundwater, a description of the current
groundwater conditions is required. The purpose of this section is, therefore to describe the prevailing
groundwater conditions. This will serve as a reference baseline for quantifying potential mining
impacts on the existing groundwater regime. Geo Pollution Technologies (Pty.) Ltd. (GPT) was
appointed to conduct a geohydrological study over the proposed Madadeni Opencast mining area and
its surrounds. The outcome of the study is attached as Appendix 3.
3 . 1 . 9 . 1 D e p t h o f G ro u n dw at e r T a b l e
Depth of the groundwater table in the study area was determined by means of a hydrocensus. From
the data it is evident that the groundwater depth varies across the site, mainly due to topography and
heterogeneity of the secondary structures in the bedrock. Groundwater levels varying between 2m
and 20m below ground level were measured during this survey.
Usually a good relationship should hold between topography and static groundwater levels. This
relationship can be used to distinguish between boreholes with water levels at rest, and boreholes
with anomalous groundwater levels due to disturbances such as pumping or local geohydrological
heterogeneities. The relationship using all boreholes is shown in Figure 10.
A contour map of the static groundwater level of the area (Figure 11) was constructed using the
Bayes extrapolated groundwater levels. Groundwater flow direction should be perpendicular to these
contours and inversely proportional to the distance between contours. Using this relationship, the
inferred groundwater flow directions are depicted as Figure 12 below with the length of arrows
proportional to the velocity. As can be expected, the groundwater flow is mainly from topographical
high to low areas, eventually draining to local streams.
3.1.10 P r e s e n c e o f W a t e r Bo r e h o l e s a n d S p r i n g s/ F o u n t a i n s
The calculated groundwater levels were also used to calculate the thickness of the unsaturated zone
(depth to the groundwater level) by subtracting groundwater levels from the topography. Contours of
the unsaturated zone thickness are depicted in Figure 13.
Existing boreholes within and around the proposed mining area were identified during a hydrocensus.
Several boreholes were identified within the vicinity of the proposed Madadeni Opencast Mining
Project. It was determined during the hydrocensus that most of the identified boreholes are in use.
Locations of the identified boreholes are shown in Figure 14. Only one hydrocensus borehole
(exploration borehole BH10), located on the new proposed mining site, could be sampled for chemical
analysis.
3.1.11 G r o u n d W a t e r Q u a l it y
Water was sampled from the boreholes identified during the hydrocensus and boreholes used for the
groundwater monitoring at the mine. The samples were submitted for major cation and ion
determination to determine the background water quality standards. These chemistry analyses
should serve as baseline water quality throughout the life of the proposed mining operations. The
results from these analyses are contained in Table 13 and compared to the SABS Drinking Water
Standards (SABS 241 Ed. 5).
The groundwater in the area can generally be classified as exceeding maximum allowable drinking
water standards, according to the SABS Guidelines for Drinking Water in terms of the sodium,
magnesium and chloride concentrations.
NKOMATI ANTHRACITE (PTY) LIMITED
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