Environmental Engineering Reference
In-Depth Information
Fig. 4.6
The shingle
beach at Anne Port, Jersey,
renourished with gravel
shipped from Ireland.
© Geostudies
4.2.9 Sediment from Mining Waste
Mining waste (sand and gravel) from tin mines in south Cornwall was piped
through a tunnel cut in 1842 in a coastal ridge to form an artificial beach in Carlyon
Bay (Figs.
4.7
and
4.8
) (Everard
1962
). The beach was eventually about 200 m
wide, with a broad convex profile, but as mining declined in the 20th century the
fluvial sediment supply diminished, and artificial nourishment of Carlyon Beach
ceased. The beach remains as one of the earliest and most substantial artificially
nourished beaches in Britain, but when the supply of mining waste halted the beach
began to erode, developing a concave profile. Continuing erosion of this beach is
likely to pose a problem for those intent on developing a seaside resort here.
An example of beach renourishment prompted by the need to dispose mining
waste has been reported from Chañaral Bay in southern Chile (Paskoff and Petiot
1990
). Between 1938 and 1975 tailings from a copper mine were dumped on the
shores of Chañaral Bay, on the Atacama Desert coast, at the rate of more than
4 million m
3
/year. They included silt and clay, which were swept offshore, but the
sandy fraction was retained to prograde the beach by an average of 900 m over this
period. After 1975 the dumping was transferred to Caleta Agua Hediona, the next
Fig. 4.7
The Carlyon Bay
coast, showing the Homebush
valley and the tunnel through
which mining waste was
diverted to the shore to
prevent it from choking the
port of Par, to the east.
© Geostudies
