long, will be refitted to work as oil accident emergency vessel that can take over oil
from a wrecked tanker, and can operate oil barriers and oil recovery equipment.
At the German North Sea coast, the Wadden-Sea area between the chain of low sandy
islands and the dikes of the mainland, a region of tidal creeks, tidal flats, and salt
marshes, is specially vulnerable to oil accidents. In case of an oil spill it would be a
primary task to protect the Wadden-Sea by constructing oil barriers across the 1-3 km
wide tidal channels between adjacent islands, in order to prevent oil from penetrating
from the North Sea into the Wadden-Sea. Unfortunately oil barriers have a poor performance in streaming water: a tidal current of 1 knot or about 2 km/h is sufficient
to carry the oil below any barrier of the types hitherto applied. Better systems
should be invented.
At the "Amoco Cadiz" accident, 11 km of oil barriers were used, mostly inflatable
constructions of the type "Sykore II" , in order to protect oyster beds, ports, and
estuaries. The results were poor, especially during the first weeks, and the experience
is that an oil barrier is as good as the crew which maintains it, because oil barriers
need constant superviSion and repair. Further, an oil barrier is useless without a
system to recover the entrapped oil and to avoid oil accumulations (Hann et al.
1978).
If all attempts to recover the oil slick from an oil accident or to prevent the oil from
approaching a shore are unsuccessful, there is a fmal chance to remove the oil from
the water surface immediately before it enters into the beach sediment or spoils a
rocky coast, by laborious hand work, with buckets and shovels, by small tractordriven vacuum trucks normally used in agriculture to pump and spread manure to
the fields, by larger vaccum trucks or by skimmers. Cleaning of oiled beaches is done
by bulldozers and other heavy gear, if the beach consists of fme hard sand, but is
much more laborious in other coastal environments. On gravel and cobble beaches,
trenches and pits are dug, in which the oily water collects after the beach has been
treated by hosing with hot pressurized water jets (80°-140°C). Cleaning of harbor
walls, rock surfaces, and individual cobbles and stones is done by hand, with hot
water jet or steam, and with detergents. One man can clean, under good conditions,
500 m 2 per day. In some areas, oiled sediment and debris are transported away and
either burnt or deposited. If beaches are important for tourist purposes, clean sand
may be brought in to replace the oiled sediment.
Wherever an oil accident has polluted a coast, careful consideration is necessary to
clean or not to clean the environment, to take the risk that cleaning operations may
do more damage to nature, or to leave the situation as it is and to wait for nature to
take care of the oil (Table 18). The Warren Spring Laboratory in the United Kingdom, which did considerable oil spill research, concludes (1972), that "from the
point of view of protection of the environment, the best thing to do with oil pollution of the beach is to do nothing. With the climatic conditions and the types of sea
around the British Islands, oil left alone will fairly rapidly become innocuous, or
disappear altogether."
103
from a wrecked tanker, and can operate oil barriers and oil recovery equipment.
At the German North Sea coast, the Wadden-Sea area between the chain of low sandy
islands and the dikes of the mainland, a region of tidal creeks, tidal flats, and salt
marshes, is specially vulnerable to oil accidents. In case of an oil spill it would be a
primary task to protect the Wadden-Sea by constructing oil barriers across the 1-3 km
wide tidal channels between adjacent islands, in order to prevent oil from penetrating
from the North Sea into the Wadden-Sea. Unfortunately oil barriers have a poor performance in streaming water: a tidal current of 1 knot or about 2 km/h is sufficient
to carry the oil below any barrier of the types hitherto applied. Better systems
should be invented.
At the "Amoco Cadiz" accident, 11 km of oil barriers were used, mostly inflatable
constructions of the type "Sykore II" , in order to protect oyster beds, ports, and
estuaries. The results were poor, especially during the first weeks, and the experience
is that an oil barrier is as good as the crew which maintains it, because oil barriers
need constant superviSion and repair. Further, an oil barrier is useless without a
system to recover the entrapped oil and to avoid oil accumulations (Hann et al.
1978).
If all attempts to recover the oil slick from an oil accident or to prevent the oil from
approaching a shore are unsuccessful, there is a fmal chance to remove the oil from
the water surface immediately before it enters into the beach sediment or spoils a
rocky coast, by laborious hand work, with buckets and shovels, by small tractordriven vacuum trucks normally used in agriculture to pump and spread manure to
the fields, by larger vaccum trucks or by skimmers. Cleaning of oiled beaches is done
by bulldozers and other heavy gear, if the beach consists of fme hard sand, but is
much more laborious in other coastal environments. On gravel and cobble beaches,
trenches and pits are dug, in which the oily water collects after the beach has been
treated by hosing with hot pressurized water jets (80°-140°C). Cleaning of harbor
walls, rock surfaces, and individual cobbles and stones is done by hand, with hot
water jet or steam, and with detergents. One man can clean, under good conditions,
500 m 2 per day. In some areas, oiled sediment and debris are transported away and
either burnt or deposited. If beaches are important for tourist purposes, clean sand
may be brought in to replace the oiled sediment.
Wherever an oil accident has polluted a coast, careful consideration is necessary to
clean or not to clean the environment, to take the risk that cleaning operations may
do more damage to nature, or to leave the situation as it is and to wait for nature to
take care of the oil (Table 18). The Warren Spring Laboratory in the United Kingdom, which did considerable oil spill research, concludes (1972), that "from the
point of view of protection of the environment, the best thing to do with oil pollution of the beach is to do nothing. With the climatic conditions and the types of sea
around the British Islands, oil left alone will fairly rapidly become innocuous, or
disappear altogether."
103