Kaibigan ng Kaunlaran at Kalikasan (KKK)
Friends of Progress and the Environment
THE CASE FOR RESPONSIBLE COAL MINING
With the continuing dependence in the foreseeable future of the Philippines on coal as fuel for base load power plants, the issue or perceptions on coal mining are revisited. A proposed coal mining site in Mindanao was studied and is the basis for this article.
Environmental Considerations
When not developed, coal mine fields pose environmental threats as a result of spontaneous combustion (the ignition of organic matter through heat generated internally by rapid oxidation). This process generates the poisonous carbon monoxide gases.
Plate 1. Spontaneous Combustion in the Mindanao Coal Field
As seen in Plate 1, a cloud of smoke rises from the spontaneous ignition of coal. Such smoke also affects adversely the surrounding vegetation and plants.
Coal Mining
There are several ways to extract coal from the ground particularly through open pit mining or alternatively contour strip mining.
Open Pit Mining
Open pit mining is generally defined as a process of extracting rock or minerals from the earth from an open pit or earth excavation. This is illustrated in the plates below.
Plate 2. Coal Mining Methods
As illustrated in the preceding plate, an open pit burrows deep into the earth. An open pit’s depth varies but the deepest open pit mine in the world is Bingham Canyon Mine in Utah. The said copper mine is 1.2 kilometers deep and four kilometers in width.
Hazards of open pit mining include damage to the landscape, contamination of water resources and disturbance of watersheds.
Damage in hardcore open pit mining may also come in the form of the release of radioactive elements, asbestos like minerals and metallic dust through tailings that may cause contamination if not properly contained.
It has to be clarified, however, that coal mining in general -- unlike metal mining -- does not cause acid mine drainage.
Why Contour Strip Mining is better
Contour Strip mining uses the natural topography of the area to remove coal deposits. The overburden (rock and soil that lies above the minerals) is removed through the contours around the area, usually a mountain or a hilly area.
Contour Strip mining entails partial coal removal as only soil or overburden is scraped off above the coal seam.
Contour Strip mining also makes possible progressive rehabilitation (i.e. the undertaking of rehabilitation works even before an entire mine are is completely mined out) for use in farming and reforestation. Its effects are reversible and can be used to cultivate barren land.
Slope protection methods and sedimentation ponds are usually set in place in Contour Strip mining areas to prevent siltation and do not pose any effects on the water system. In contrast, open pit involves deep excavations and steep slopes which make it generally vulnerable to erosion and sedimentation.
The key environmental measures in contour strip mining are:
- Immediate Rehabilitation of side cuts being mined
- Backfilling and rehabilitation of succeeding side cuts
- Stripping, backfilling and rehabilitation
- Erosion and sedimentation controls
These measures are generally absent in the case of open-pit mining as evident in documentary and video evidences related to damage to mining area landscapes and watershed areas, the latter leading to the contamination of water resources.
These measures are generally absent in the case of open-pit mining as evident in documentary and video evidences related to damage to mining area landscapes and watershed areas, the latter leading to the contamination of water resources.
Sequential phases in Contour Strip mining are illustrated in the sequence of images below:
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