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

Source of impact
Seepage from the stockpiles and AMD from mining operations causes a contamination plume affecting the
underground resources which in turn affects surface water resources. Contamination may also occur directly into
surface watercourses.
Hydrocarbon-based fuels or lubricants spilled from construction vehicles.
Description of the impacts
Surface mining generally removes 90% or more of the coal (which often contains the highest sulphide content
and hence the acid-producing potential) thereby leaving little in the backfill for continued reaction and acid
generation. Pyrite is often dispersed among other rocks above and below the coal seam. The pyrite-bearing
rocks and coal left behind are broken apart by blasting giving high surface area, and the acid products are
leached fairly rapidly, typically within 10 to 20 years (Demchak et al, 2004). Carbonate rocks within the
overburden may neutralise some or all of the AMD generated during surface mining. Special handling of toxic
materials may reduce the amount of pyrite oxidized, and the addition of alkaline material during mining may
neutralize acid in situ, both of which decrease the total acid load coming from the site (Demchak et al, 2004).
During the ensuing 20 yr after reclamation, discharge water quality may reach pre-mining levels.
Hydrocarbon-based fuels or lubricants spilled from construction vehicles, construction materials that are not
properly stockpiled and litter deposited by construction workers may also be washed into the surface water
bodies. Should appropriate toilet facilities not be provided for construction workers at the construction crew
camps, the potential exists for surface water resources and surroundings to be contaminated by raw sewage.
The utilisation of the water courses for disposal of water used for washing will decrease the abundance and
diversity of aquatic macroinvertebrates inhabiting wetlands associated with the proposed development and
further downstream. Contaminated runoff from concrete mixing and sediment release including hydrocarbon
spillages may lead to the infiltration of toxicants into the groundwater.
Significance:
The significance is assessed to be medium high.
Mitigation:
• To assess the impacts of the stockpile area on the groundwater regime a groundwater analysis need to
be undertaken;
• A contaminant plume after 5, 10, 15, years should be modeled. Contaminated groundwater from the
stockpile area will migrate and this assessment need to determine the direction and propose possible
mitigation measures;
• The contaminant plume could result in an impact on downstream water bodies, aquatic ecosystems and
surrounding landowners, especially in the long term (more than 50 years);
• Disposal of coal stockpile on natural clay;
• Management of the stockpile in accordance with Section 73 of the MPRDA Regulations (No. R527,
2004).
• Vehicles are to be maintained in good working order so as to reduce the probability of leakage of fuels
and lubricants.
EIA-REP-325d-11
October 2012
124