In the event of a major incident occurring offshore, for
example a tanker casualty running aground or breaking up
for any reason, it is of paramount importance to deploy
emergency response to protect and save human life. Once
this has been done an assessment of the casualty should
be made on whether it is possible to salvage the vessel
and its contents and to assess the type and amount of oil
that is being spilled.
All this is carried out by an
incident room, which should be set up at the nearest
port/land base, from which equipment and manpower
can be deployed. This should be supported by a crisis
management team and offshore/onshore teams to co-ordinate
the spill response and salvage operations. Aerial
recognisance should also be set up immediately, whether
it be fixed wing or other aircraft, to monitor oil
slicks as they develop.
If through wind and tide the slick is
being blown out to sea then it is best for nature to take
its course and allow natural dispersion to take place. If
it is likely that the oil should make a landfall, all efforts
should be made to recover as much oil at sea as is possible.
Oil recovery at sea
Equipment deployed at sea will usually
be containment and recovery systems incorporating long lengths
of boom to corral oil slicks to provide a build up and encounter
rate of oil to match the designed recovery capability of
mechanical skimmers. Historically these skimmers are not
very efficient and are very expensive to deploy, sometimes
requiring 2 or even 3 vessels and all the ancillary equipment
and manpower for deployment and recovery.
OPEC Force 7 utilises
the well established adsorption characteristics of
polypropylene mops and we have developed a surface
trawl mop net which when deployed on the open sea
gives a trapezoidal configuration and a swathe path
of 15 metres and a net length of 60 metres with an
adsorption capability of up to 12 tonnes. The cycle
operation allows a deployment and retrieval cycle
of 7 times per hour giving a recovery rate of 70 tonnes
This is a single ship deployment
system without the need for containment booms.
|Fig. 1 An illustration
of the Force 7
Due to national or international maritime
rules, vessels used in oil recovery may not be classed to
allow recovered oil to be stored in inboard tanks. Therefore
it is important to also have towed temporary recovered oil
storage tanks available to allow the operation to continue
without the need for support vessels. The OPEC Flexitanks
were developed and designed for this purpose and are supplied
in standard sizes between 5 tonnes and 100 tonnes recovered
oil storage capacity. These can be folded up and stored
on deck when not in use and have in-built buoyancy to assist
in deployment and retrieval.
With such a system
there is the obvious advantage of using 1 vessel.
The recovery costs are minimised since all vessels
available can be used to the maximum effect, operating
costs are much lower, manpower requirements are much
lower, ongoing training and maintenance costs again
are very much lower. Definite alternatives to be considered
for future offshore cleaning operations at sea.
|Fig. 2 An example of a 25 tonne
Flexitank on board ship with a Force 7
Oil recovery on land
It must be expected that whatever
means are used not all of the oil will be recovered at sea
and landfall will occur, in which case oil/debris containment
booms should be deployed to minimise the area of pollution
along the coast by deploying the boom in such a way as to
deflect the oil to sacrificial beaches. These should have
good access for equipment and manpower and be as far away
as is possible from the natural habitat of marine creatures
and docks and harbours.
In the event that
polluting oil makes landfall, whether or not it be
a sacrificial beach, OPEC have specialised equipment
which can remove this oil along the shoreline. The
Series 5000 has been specifically developed to deal
with heavy oils and heavily weathered crude oil and
can be used in boomed areas to recover large quantities
of oil very quickly. The equipment will pick up oil
with very little free water and incorporates an integral
pump system to allow the transfer pumping of recovered
oil to pits which can be subsequently emptied by gully
suckers/tankers or directly to tankers. If the oil
gets on to the beach, trenches can be dug and OPEC
E-Series mop skimmer systems can be deployed to recover
the oil gathering in the trenches. In some cases the
mop skimmer can also be deployed over the surface
of the beach area as required.
In the event of small pockets of
oil being removed in rock pools etc., the Hand Mops
can be used together with a versatile wringer which
can be mounted on open topped 200 litre drums and
will provide a contingency operation with very little
disposal costs of contaminated adsorbent material.
|Fig. 3 The resultant outcome when unable
to create a sacrificial beach
|Fig. 4 The resultant outcome when
unable to create a sacrificial beach
|Fig. 5 Example of a Series 5000
beach cleaning system Series 5000
We would not recommend
the use of adsorbent fabric and adsorbent booms for
this type of work since the ongoing disposal costs
are high. (However there are exceptions, see A Method
for Cleaning Foreshores). In one incident that occurred
in Year 2000 it was reported that a spill of 20,000
tonnes has resulted in the removal of over 200,000
tonnes of contaminated material - a lot of which was
adsorbent of one sort or another. With the proper
use of specially designed equipment and properly deployed
manpower, costs would be reduced dramatically.
|Fig. 6 Example of removing
oil from rock pools
The use of dispersants
should be kept to a minimum; it should never be used
as the main line of attack on an oil spill. Problems
occur when trying to deal with weathered and emulsified
oils which have been treated with dispersants. Mechanical
removal methods must be the preferred method.
|Fig. 7 Photograph shows a temporary
waste disposal site at the Exxon Valdez Spill
Dispersants used on an oil slick
can cause the following problems:
- Adding chemicals to an oil spill
only further adds to the amount of environmentally damaging
- By dispersing the oil into the water
column some will fall to the bottom and create pollution
to bottom feeding marine life.
- The oil that remains in the water
column may well eventually make landfall and because it
has been dispersed will pollute a much wider area.
- Also the chemical structure of the
oil will be altered and may make it more difficult to
High power jet sprays should also
be avoided when cleaning rocky beaches:
- Power jets temporarily push the oil
from one area to another. The oil is blasted further down
into the sand or pebbles. This does not reduce the amount
of pollution that already exists in a pollution spill.
- Power jets disturb the ecological
surroundings, moss, seaweed's etc.
- The detergeants used in power washing
only add to the environmentally damaging toxins.
So what can you
do when oil is sticking to rocky outcrops at the sea
edge? One solution could be to apply the technology
of 'bioremediation'. Biochemistry means powerful cleaning
without the use of harsh man-made chemicals. In this
instance OT8 Gel can be applied and simply left to
'eat' the hydrocarbons until there is nothing left
apart from water and 'dirt' which would simply wash
away through natural factors such as the wind, rain
and wave action of the sea.
|Fig. 8 Example of power washing
at an oil spill site
From the information given above
here is a suggested contingency plan for dealing with an
offshore oil spill.
1. Coast Guard to deploy emergency response
team in the effort to preserve human life.
2. Marine engineers to assess the damage
and try to salvage the vessel to reduce the amount of pollution
discharged at sea.
3. Assess the type and amount of oil
that has been spilled.
4. Monitor the oil spill from an incident
room and aerial recognisance.
5. Crisis management team to coordinate
offshore and onshore teams for spill response.
6. If there is a threat of oil coming
ashore deploy offshore teams with mechanical pollution recovery
equipment. Attempt to recover as much oil at sea as possible.
7. Using data from the aerial recognisance,
weather reports and admiral charts use onshore teams to
deploy oil/debris containment booms to deflect the oil to
a sacrificial beach.
8. At the designated area for the sacrificial
beach deploy mechanical oil recovery equipment and prepare
trenches for the collection and temporary storage of the
9. Use hand mops for rock pools and hard
to reach areas.
10. Use bioremediation products, such
as 'OT8' for the removal of oil from rocky outcrops.
A contingency plan
is essential for all port and harbour officials and
emergency response crisis teams.
The management involved in a pollution
response project should be aware of the expertise
and equipment available to them in order to be as
efficient and as effective as possible with the minimum
amount of waste.
|Fig. 9 Example of oil sticking to
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