The largest physical disturbances at a
mine site are the actual mine workings,
such as open pits and the associated
waste rock disposal areas (Fig. 6). Mining
facilities such as offices, shops, and mills,
which occupy a small part of the disturbed
area, are usually salvaged or demolished when
the mine is closed. The open pits and waste rock
Fig. 6. The light-colored bare piles of waste rock
near these houses in Butte, Montana, remain from
the early underground mines. Open pit operations
followed, and some waste rock and mill tailings
from that stage show in the distance.
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disposal areas are the principal visual and aesthetic impacts of mining.
These impacts remain on the landscape until the disturbed areas are
stabilized and reclaimed for other uses, such as wildlife habitat or
recreation areas, after mining has ceased.
Underground mining generally results in relatively small waste
rock disposal areas ranging from a few acres in size to tens of
acres (0.1 km2). These areas are typically located near the
openings of the underground workings. Some waste rock
areas, if not properly managed, can be sources of significant
environmental impacts, such as stream sedimentation if
erosion occurs, or the development of acidic water
containing metals.
Open pit mining disturbs larger areas than underground mining, and
thus has larger visual and physical impacts. As the amount of waste
rock in open pit mines is commonly two to three times the amount of
ore produced, tremendous volumes of waste rock are removed from the
pits and deposited in areas nearby. During active mining operations,
this type of waste rock area (Fig. 7) and the associated open pit, are
very visible physical impacts. Although the physical disturbance associated with metal mining can be locally significant, the total land area
used for metal mining is very small compared to other major types
of land use