An Overview of Environmental and Social Risks and Potential Financial Implications - Mining and the Environment: From Ore to Metal - page 567

Appendix 13.1
An Overview of
Environmental and Social
Risks and Potential
Financial Implications
Environmental Risks and Financial Implications
ENVIRONMENTAL AND SOCIAL RISKS
Direct Risks
Land requirement - Land areas for open pit excavation, dumping of mine wastes external to the pit or underground voids, and the construction of transporta-
tion corridors and infrastructure may destroy surface features of economic, cultural, or nature conservation value.
Waste rock disposal areas - Waste rock may contain heavy metals. If waste rock contains sulphur, acid rock drainage may occur. Runoff or leachate may contain
elevated concentration of metals and low pH values posing a particular threat to the aquatic environment long after mine closure.
Tailings storage areas - Tailings may contain heavy metals, sulphur, or mill reagents. Acid rock drainage potentially occurs. Runoff or leachate from tailings storage
areas may contain elevated concentrations of these elements and low pH values imposing a particular thread to the aquatic environment. Discharge water may
qualify as effl uent.
Stockpile areas - Stockpiles may contain heavy metals and mineral oxidation products. Runoff and leachate may contain elevated concentration of heavy metals
and be of acid pH. Spontaneous combustion of coal stockpiles and spoil heaps may occur if coal residues are present in the heaps.
Geotechnical stability - Inadequately designed and maintained pit faces, spoil heaps, waste rock dumps, or tailings dams may become unstable leading to ground
or tip collapse. Failure of tailings containment will result in the release of large volume of potentially hazardous tailings.
Ground subsidence - Surface damage due to ground subsidence is a major risk of underground mining. Structural damage to buildings, infrastructure, agricultural
land and drainage system may occur, in particular if signifi cant differential subsidence occurs.
Water erosion - Disturbed land is subject to water erosion and subsequent impacts on the aquatic environment. Land disturbance occurs due to direct mining
activities as well as due to any other construction or land clearing activity (such as road construction). Runoff may be of acid pH with elevated concentrations
of heavy metals.
Mine dewatering - Groundwater from mine dewatering discharged to surface water may be acid in nature and contain elevated concentrations of dissolved
metals due to mineral oxidation and dissolution within the mine. Groundwater draw down may lead to drying up of well, springs, wetlands, or entire surface
water bodies. Depending on geology, groundwater abstraction may lead to ground subsidence.
Groundwater rebound - Cessation of pumping at the end of mine life will result in groundwater rebound (rising groundwater levels) leading to surface discharge
of potentially contaminated mine water. Groundwater rebound may also lead to ground instability and potentially fl ooding in areas distant from the mine.
Groundwater rebound may pollute upper aquifers.
Waste generation - Increased population and workforce will generate sanitary waste. Industrial wastes originate from workshops, broken equipment, unused
materials, waste tires, scrap metal, power generation and many other activities related to mine operation. Health facilities will generate medical waste. Waste
rock and tailings, however, will always dominate the generated waste streams.
(Continued)