BALTIC SEAENVIRONMENT PROCEEDINGS No. 59 - Helcom

ships with integrated oleophilic rope or brush skirrrners, ships with sweeping
arms or spring sweep systems e.g. should Closely follow the towing unit with
the concentrated oil.
2.6 The use of skimners in combatting oil pollution is advisable in connection
with containment booms but also specialized oil recovery vessels can be mobilised
for recovery actions. The specialized oil recovery vessels in general
have high performance oil collection devices but the oil content of the
recovered mixture - if, e.g. weir skirrrrter systems or sweeping arms are used
- is mostly lesser than 20 %. As the gravity separation process takes hours
it is necessary to install additional high performance separators in order
to fill the storage tanks with separated oil.
The disadvantage of specialized recovery vessels is often their non-versatility
for other task like fire-fighting or buoy-tender-tasks.
Smaller skimners like weir skimners, disk skimners, belt skimners, oleophilit
rope skimners, vortex skirnners etc. in general have lower recovery performance
but the oil proportion is much higher than the water contents of
the recovered mixture.
The main advantage of a single or multi-vessel operation without utilization
of long boom barriers ist the high flexibility of the single vessels, a
higher recovery speed and in areas of widespread layers and windrows faster
transfers from one recoverable slick to the other. Also, lightering operations
of oil recovery vessels are much easier to manage. The classification
societies have meanwhile ruled the construction of these vessels, including
safety measures to avoid explosion or toxic hazards.
Combinations of hopper dredgers or buoy-tender vessels with sweeping arms
in connection with brush skimners or suction pumps can significantly contribute
to a reduction of maintenance and operation costs. Therefore for a tier
3 response in a major diseaster at sea at least one high performance vessel
must be available to encounter imediately the spreading slick. 2 tugboats
or auxiliary vessels are needed to contain or concentrate the leaking oil in
case of a continuous outflow or to prevent strong slick patches from further
spreading. This capacity must be widened if a grave spill has to be reacted.
2.7 The removal of oil from shorelines is usual ly carried out in two stages:
a) the primary phase, which consists of removal of floating oil and heavy
contamination as soon as possible in order to avoid further pollution;
b) the final cleaning phase, which is to remove the final traces of oil and
oily stains.
The Collection of stranded oil can involve pumping, mechanical or manual removal
of oil or the use of specialized collection equipment.
The pumping and skimming liquid oil is the easiest way of collection. Vacuum
device are the most efficient way of pumping oil because the pollutant which
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