Environmental Engineering Reference
In-Depth Information
9.4
LAND POLLUTION
In regard to fossil fuel use, the heaviest toll on land impact is due to coal mining—in particular,
surface mining, also called strip mining. In the United States, more than 60% of about 750 million
metric tons of coal mined annually is surface mined. Because the coal seam is rarely on the surface
itself, this requires removing the “overburden.” The latter can amount to up to 100 m of soil, sand,
silt, clay, and shale. Some coal seams appear in hill sides and river banks. Here the coal is removed
by auger mining, which uses a huge drill to dig the coal out of the seams.
Surface mining leaves behind enormous scars on the landscape, not to mention the disruption of
the ecosystem that existed before mining started, or the loss of other possible uses of land instead
of mining. For that reason, the U.S. Congress in 1977 passed the Surface Mining Control and
Reclamation Act. The law delegates to the states the authority to devise a permitting plan that must
include an environmental assessment of the mining operations, and procedures for reclamation
of the land after cessation of operations. The permitting plan must describe (a) the condition,
productivity, uses, and potential uses of mine lands prior to mining and (b) proposed post-mining
reconditioning of the mined lands, including revegetation. Stringent operational standards apply to
mining in critical areas, including those with slopes greater than 20 degrees and alluvial valleys.
The land must be restored to a condition capable of supporting any prior use and possible uses to
which the land might have been put if it had not been mined at all. Needless to say that this law, and
the requirements for safe and ecologically sound surface mining practices, imposed a great effort
and economic burden on surface mining companies and indirectly raised the price of surface-mined
coal.
Deep shaft mining also places a burden on the land. We mentioned earlier that the mined coal
is brought to the surface, where it is crushed and washed. The removed mineral matter accumulates
in enormous slag piles that mar and despoil the landscape. Nowadays, strict regulations pertain in
the United States and other countries as to the disposal of the coal mine slag and restoration of the
landscape.
Finally, we should mention that the vast number of derricks associated with oil and gas ex-
ploration and exploitation is neither an aesthetically pleasing sight nor helpful to the ecology that
existed on the land prior to oil and gas mining.
9.5
CONCLUSION
The consumption of vast quantities of fossil fuel by mankind causes many deleterious environ-
mental and health effects. These effects start from the mining phase of the fossil fuels, through
transportation, refining, combustion, and waste disposal. When coal is mined in deep shafts or in
strip mines, mineral matter is separated at the mines by milling and washing. The residual slag may
contain toxic, acidic, and sometimes radioactive material, which needs to be properly disposed of
without endangering the environment and humans. Oil and gas well derricks, on- and off-shore,
are aesthetic eyesores and are the cause of oil spillage. Oil and gas pipes may rupture and leak their
contents. Oil tankers and barges spill on the average 4 million tons per year of crude and refined
petroleum on our waterways and oceans. Oil refineries are sources of (a) toxic emissions through
vents, leaks, and flaring and (b) toxic liquid effluents and solid waste.
