THE PROBLEM O F OIL POLLUTION O F THE SEA
225
valves to handle and a far greater pumping rate, there is a considerably
increased danger of pollution; on the other hand, oil-jetty and tanker
crews have the advantage of training and experience. An American
Petroleum Institute manual (1 964) deals with all pollution-control
aspects of tanker loading and unloading operations. Dudley (1968,
1969) concludes that the major cause of oil-port pollution is human
error-partly
through poor communication and partly because of
inattention or carelessness. I n Milford Haven, where development
as a major oil port has taken place very rapidly, it is observable that
each terminal suffers a rash of incidents (most of them fortunately
minor) during its first few weeks of operation, until its jetty crew gains
experience.
It occasionally happens that a tanker enters her unloading port with
hull damage sustained en route. If her tanks were ruptured below the
waterline, oil will have escaped to be replaced by water, but as she is
unloaded and her buoyancy increases, this water will flow out and will
eventually be followed by the remaining oil. Kluss (1968b) describes
the similar situation of a tanker stranded on a falling tide. Damage of
this sort caused an overnight leakage of 250-500 tons of crude oil from
the " Chryssi P. Goulandris ') into Milford Haven in January 1967
(see Nelson-Smith, 1968a, b). I n 1962 the " Benjamin Coates )' was
holed in several places along the bottom of her hull when she hit rocks
in the mouth of the Haven, but in this case oil escaped only immediately after the impact. Sea water was pumped into the damaged tanks
to raise the level of the remaining oil, which was then unloaded from
above by portable pumps (Dudley, 1968).
In still waters, a leaking tanker can be surrounded by a floating
spillboom, which contains the oil until it is pumped off or soaked up.
Some booms are themselves made of, or stuffed with, absorptive
materials such as fibrous polypropylene. Commercial booms consist
basically of a floating barrier supporting a weighted skirt. Experience
has shown that although they are little affected by a slight swell,
choppy waves exceeding 6 inches slop oil over the barrier, while a
current greater than 1+-2 knots lifts the skirt or carries oil beneath it
(Hydraulics Research Station, 1967 ; Mayo, 1968 ; Dudley, 1969). A
disadvantage for more routine use in oil docks is that a continuous
boom blocks the passage of traffic. Most designs are made in jointed
sections which can be dismantled, while one air-filled type sinks to the
bottom when deflated (Anon., 1962). I n harbour mouths (or, equally,
to prevent an offshore slick from penetrating an estuary) the Hydraulics Research Station suggests a '' chicane ) ' of two curved booms, overlapping but staggered. A more promising alternative seems to be the
225
valves to handle and a far greater pumping rate, there is a considerably
increased danger of pollution; on the other hand, oil-jetty and tanker
crews have the advantage of training and experience. An American
Petroleum Institute manual (1 964) deals with all pollution-control
aspects of tanker loading and unloading operations. Dudley (1968,
1969) concludes that the major cause of oil-port pollution is human
error-partly
through poor communication and partly because of
inattention or carelessness. I n Milford Haven, where development
as a major oil port has taken place very rapidly, it is observable that
each terminal suffers a rash of incidents (most of them fortunately
minor) during its first few weeks of operation, until its jetty crew gains
experience.
It occasionally happens that a tanker enters her unloading port with
hull damage sustained en route. If her tanks were ruptured below the
waterline, oil will have escaped to be replaced by water, but as she is
unloaded and her buoyancy increases, this water will flow out and will
eventually be followed by the remaining oil. Kluss (1968b) describes
the similar situation of a tanker stranded on a falling tide. Damage of
this sort caused an overnight leakage of 250-500 tons of crude oil from
the " Chryssi P. Goulandris ') into Milford Haven in January 1967
(see Nelson-Smith, 1968a, b). I n 1962 the " Benjamin Coates )' was
holed in several places along the bottom of her hull when she hit rocks
in the mouth of the Haven, but in this case oil escaped only immediately after the impact. Sea water was pumped into the damaged tanks
to raise the level of the remaining oil, which was then unloaded from
above by portable pumps (Dudley, 1968).
In still waters, a leaking tanker can be surrounded by a floating
spillboom, which contains the oil until it is pumped off or soaked up.
Some booms are themselves made of, or stuffed with, absorptive
materials such as fibrous polypropylene. Commercial booms consist
basically of a floating barrier supporting a weighted skirt. Experience
has shown that although they are little affected by a slight swell,
choppy waves exceeding 6 inches slop oil over the barrier, while a
current greater than 1+-2 knots lifts the skirt or carries oil beneath it
(Hydraulics Research Station, 1967 ; Mayo, 1968 ; Dudley, 1969). A
disadvantage for more routine use in oil docks is that a continuous
boom blocks the passage of traffic. Most designs are made in jointed
sections which can be dismantled, while one air-filled type sinks to the
bottom when deflated (Anon., 1962). I n harbour mouths (or, equally,
to prevent an offshore slick from penetrating an estuary) the Hydraulics Research Station suggests a '' chicane ) ' of two curved booms, overlapping but staggered. A more promising alternative seems to be the