The Operational Use Of Dispersants in the United Kingdom

PAJ Symposium, Tokyo, February 2004

The Operational Use of Dispersants in the United Kingdom
Introduction
The use of oil spill dispersants in the United Kingdom Pollution Control Zone has
been an accepted operational policy for many years. Very detailed licensing andoperational procedures are in place to ensure dispersants are used in the mostefficient, effective and economical way directly linked to net environmental benefit.
This paper will cover four main areas linked to the operational use of dispersants in
the United Kingdom.
Firstly a very brief history lesson with regards to pollution and salvage response in
the United Kingdom. Secondly dispersant licensing issues and their use in the United
Kingdom pollution control zone, thirdly some information on a recent sea trial
involving the use of dispersant at sea on a variety of oil types in UK waters; andfinally the resources available to the Maritime and Coastguard Agency to combat amajor spill of oil linked to the use of dispersants.
Some History
The UK has been unfortunate in experiencing, and having to respond to, three of the
top twenty oil spills in the world. We are therefore well rehearsed in dealing with suchdisasters. However, each incident brings its own particular problems. There arealways lessons to be learnt.
1967 was the first time the attention of the world was turned on the UK for a major
pollution incident. The Torrey Canyon ran aground between the Isles of Scilly andLand End – the south-western corner of the UK. She was carrying 117,000 tonnes of
Kuwait crude. After a failed salvage attempt she was eventually bombed to burn off
the remaining 20,000 tonnes of crude oil.
The UK Parliamentary response to this incident was to enact the Prevention of Oil
Pollution Act of 1971 and the associated intervention powers. These are now
enshrined in the Merchant Shipping Act 1995 and Marine Safety Act 2003. The
incident also provided the catalyst for International maritime Organisation (IMO) 1969
CLC/1971 Fund regime for liability and compensation regimes.
Such an event was unplanned and unparalleled. The UK had no National
Contingency Plan, no national stockpiles, no emergency towing vessels, and nopolicy to deal with such a disaster. In effect no prevention, preparedness or response
strategies. Pollution control was, at this time, still a relatively minor concern for IMO
and member countries.
Time drifted on. It was human error that caused the accident, it was considered
unlikely to happen again and the incident faded in the public conscience. In the
background, the world and in particular IMO, began asking questions aboutmeasures in place to prevent oil pollution from ships, along with issues of liability.
This incident was the catalyst for the adoption of MARPOL and a host of initiatives
linked to the protection of the marine environment.
In 1978 the AMOCO CADIZ grounded off the Brittany coast, this time In Frenchwaters. The incident happened one month after the 1978 International Maritime
Organisation (IMO) Conference on Tanker Safety and Pollution Prevention. The
tanker held 223,000 tonnes of crude oil.

Toby Stone - Maritime and Coastguard Agency

Page 1

The Operational Use Of Dispersants in the United Kingdom

PAJ Symposium, Tokyo, February 2004

The EXXON VALDEZ grounding during 1989 in Prince William Sound and thesubsequent birth of the Oil Pollution Act 1990 (OPA90). The IMO Oil Pollution,
Preparedness, Response and Co-operation Convention (OPRC) was als o coming tofruition.
Time drifted on again. It was the UK’s turn in 1993 when the M/V BRAER went onto
rocks at Garth Ness, at the southern tip of the Shetland Islands. She was fully ladenwith 84,700 tonnes of Norwegian Gullfaks crude and some 1,600 tonnes of heavy
fuel oil bunkers. The weather was atrocious, storm force winds and mountainousseas. There were all the makings of a major economic and ecological disaster for the
local community and environment. If there was a silver lining in the cloud it was thefact that Gullfaks is a very light and volatile crude with very low asphaltene content
which the high winds and exceptional seas were largely able to disperse. The
consequences though were still serious. This was the second major spill, ranked in
the top twenty of all worldwide spills that the UK had to contend with. On thisoccasion the UK did have a National Contingency Plan and associated resources inplace. Dispersants were used on the oil slick.
As with all major incidents and disasters there are always lessons to be learnt. Afterthe Braer incident Lord Donaldson of Lymington was appointed chairman of theenquiry. The subsequent report, Lord Donaldson’s Inquiry into the Prevention of
Pollution from Merchant Shipping, detailed no less than 103 recommendations toGovernment. The report is more commonly referred to as Safer Ships, Cleaner Seas.
The recommendations were very wide ranging, encompassing all aspects of global
shipping. The report principally concluded that whilst much work was already being
done, there was a pressing need for the United Kingdom to take new initiatives
locally, regionally, nationally and internationally.
The UK response was adapted and updated in light of some of the recommendations
in safer Ships and Cleaner Seas. This was in conjunction with IMO OPRC
Convention requirements. The UK had yet to accede to the OPRC Convention, but
had many of the requirements in place, for example a National Contingency Plan.
Safer Ships Cleaner Seas led directly to the establishment of Em ergency Towing
Vessels in the UK.
The clock ticked on. In February 1996, the SEA EMPRESS grounded, oddly enoughjust a day after a major UK oil spill exercise, and the subsequent salvage operation
unfolded before the eyes of a startled nation. This third incident ranked in the global
top twenty of all pollution incidents from shipping had occurred in UK waters.
The incident attracted enormous public interest and provided the news media withheadlines for several days as efforts to salvage the tanker and prevent massive oil
pollution unfolded before the cameras of the world. 130,018 tonnes of Forties lightcrude oil threatened to pollute UK waters. She had run aground on the final
approaches to the port entrance, pilot on board. The weather was fine and clear witha west northwesterly force 4/5 wind. Both engines were put astern, both anchors
were deployed, but the vessel continued ahead and ran aground 5 cables to thenortheast of the original grounding position. Oil immediately began escaping from theship. It was a disaster, a national disaster of the worst kind, again, in a highly
environmentally sensitive area. Again dispersants were used on the oil slick.
Lord Donaldson conducted a Review of Salvage and Intervention and their
Command and Control. It was generally agreed there was a text book clean-up
operation of the pollution both at sea and on the shoreline. There were however

Toby Stone - Maritime and Coastguard Agency

Page 2

The Operational Use Of Dispersants in the United Kingdom

PAJ Symposium, Tokyo, February 2004

possible enhancements with regards to the operational response to salvage andintervention. The outcome of Lord Donaldson's Report was to dramatically alter theway that the UK responds to maritime casualties.
It was an opportune moment. The Coastguard Agency and Marine Safety Agency
were being amalgamated to form the Maritime and Coastguard Agency (MCA). The
future maritime response for the UK was being altered accordingly to reflect some of
the 26 recommendations made in Lord Donaldson’s report.
The four main theatres of activity
In light of Lord Donaldson’s report the UK considers now four main theatres ofactivity:Firstly Search and Rescue. This is co-ordinated by Her Majesty’s’ Coastguard at
one of eighteen rescue centers in the UK. HM Coastguard is a part of the MCA.
Secondly Dealing With the Casualty. This, in marine terms, is the salvage elementof the business. At the time of a marine casualty, where appropriate, the UK
government encourages a contract, usually Lloyds Open Form, between the owners
and a reputable salvor. The decisive voice in this equation is the Secretary of States
Representative (SOSREP), who has the ultimate control of the salvage operation,
usually through the Salvage Control Unit (SCU). Note that: no action, once informed
via an MRCC, means tacit approval to the salvage operation.
Thirdly At Sea Clean Up. This is through a Marine Response Center (MRC) set up in
the port area or nearest suitable MCA premises. The control of the unit is initially by
the port. As the incident grows beyond a tier 2 then MCA take control as required.
This control cell deals with all of the issues concerned with dealing with oil afloat
including the use of dispersants.
Fourthly Shoreline Clean Up. This is controlled by a Shoreline Response Centre(SRC) and managed by local authorities. MCA supports and provides advice to the
local authorities in the establishment and running of the SRC.
Environmental considerations are catered for by the establishment of an Environment
Group, provided advice to the three cells, namely the SCU, MRC and SRC. Standing
environment groups are established around the UK. The chair is nominated at thestart of an incident. Environmental Liaison Officers sit within the SCU, MRC and SRC
cells to provide all aspects of environmental advice.
The National Contingency Plan
These operational response arrangements are detailed in the MCA National
Contingency Plan. This plan also highlights the resources central government has at
its disposal. Such resources must clearly dovetail with local and regional plans of all
the ports and harbours in the United Kingdom. All such plans are encompassed by
the OPRC requirements.
One important key to preparedness includes some 180 ports and harbours to haveapproved OPRC Oil Spill Contingency Plans. These ports are considered to be thehighest risk. In addition several hundred Offshore Plans have also been approved
encompassing Oil and Gas exploration, development and production. A number ofthese plans nominate dispersants as an option for combating pollution.

Toby Stone - Maritime and Coastguard Agency

Page 3

The Operational Use Of Dispersants in the United Kingdom

PAJ Symposium, Tokyo, February 2004

To support the OPRC concept the UK has implemented accreditation schemes forresponders, trainers, and port and offshore installation operators. The British Oil Spill
Control Association and the Nautical Institute administer these schemes on behalf ofthe MCA.
Introduction to dispersantThoughtless and uncontrolled use of chemicals in the sea or on the shoreline to treat
oil can cause more problems than would have occurred if the oil had been left alone.
This may be due to the toxicity of the chemicals themselves or because thechemicals disperse oil into the water column where the dispersed oil in highconcentrations could affect fish and shellfish living below the surface of the sea.
In some cases however, dispersant use can be very effective in preventing damage
to wildlife and contamination of recreational beaches by removing oil from the surfaceof the sea or the shoreline. For these reasons the UK Government has set up a
regulatory and advisory regime to protect the environment from indiscriminate use ofdispersants and to encourage appropriate use of dispersants and other chemicals
where this would be beneficial to the environment.
The licensing authorities
The statutory licensing authorities responsible for approving dispersant products foruse at sea are as follows:?? Department of Environment for Rural Affairs (Defra), England and Wales?? Scottish Executive for Environmental & Rural Affairs Department (SEERAD)?? Environment & Heritage Services, Northern Ireland (EHS)
Licensing Authority approval is not formally required where dispersant use isrestricted to those parts of a beach above the height of mean high water spring tides
or in situations where products are only applied manually not involving the use of
aircraft, vessels or where approved products are used in deeper water more than one
mile away from the 20 metre contour line.
There are however situations where there are no or minimal restrictions on
dispersant use where environmental damage may nonetheless be caused byinappropriate use. The licensing authorities therefore encourage anyone proposing
to use oil dispersants or other oil treatment products to consult the appropriate
Licensing Authority in advance on all proposals to use oil dispersants.
Using dispersantsUnder the terms of the UK Food and Environment Protection Act (FEPA) 1985 andthe Deposits in the Sea (Exemptions) Order 1985, it is a legal requirement that
dispersants may normally only be used in UK waters if they have been formallyapproved for this purpose by the licensing authority.
In addition, specific permission from Defra, SEERAD or EHS must be obtained under
this legislation before any dispersants are used in shallow waters – these are defined
as any sea area which is less than 20 metres deep, or within one nautical mile ofsuch an area. This covers all areas submerged at Mean High Water Springs
including any use in tidal docks and locks and on beaches, shorelines, or structures
such as piers and breakwaters.

Toby Stone - Maritime and Coastguard Agency

Page 4

The Operational Use Of Dispersants in the United Kingdom

PAJ Symposium, Tokyo, February 2004

Use of approved dispersants in deeper waters is generally less likely to cause
damage and is therefore not subject to the same restrictions as inshore use.
Although certain small scale manual clean up operations and those taking place
above Mean High Water Springs, are not subject to the provisions of FEPA, any
inappropriate use of dispersants or other chemicals can cause significant damage toimportant fisheries, nature conservation areas and economic utilities such as power
stations with seawater intakes.
It is therefore of utmost importance that anyone proposing to use oil dispersantsconsult the Licensing Authority in advance on any proposed use of dispersants evenon a small scale and only use approved products.
I should also mention that approved dispersants can, exceptionally, be used without
prior consultation with the licensing authority in force majeure situations where there
is a genuine risk to human life or to the safety of an installation or vessel – forexample, where there is a serious danger from fire or explosion.
Detailed guidance on the appropriate use of oil treatment products is given in the
Defra booklet “The Approval and Use of Oil Dispersants in the UK”. In addition there
is a website which is continually updated to provide a comprehensive list of approved
dispersants in the UK.
The booklet stresses that for many oil spills, the best option is to leave the oil todisperse and/or degrade naturally, or use another form of intervention may beappropriate for example mechanical recovery or the use of containment booms.
Spraying dispersant is not appropriate for all types of oil - for example, diesel, gas oil
and other light oil types usually disperse readily and therefore do not require
treatment. Sea conditions, tides and a number of other factors are also important indetermining whether dispersant use is the most appropriate response. In addition,
there is a wide range of oil treatment products available which have different
properties and may be suitable for use only on certain types of oil and under certain
sea conditions.
Good contingency planning is the key to the successful use of dispersants. Some ofthe oil spill plans in the UK which encompass larger estuaries, for example Humber
Estuary, have pre-agreed strategies for such use. Detailed sensitivity maps clearly
indicate where the use of dispersant is appropriate. Further detail includes very
comprehensive information of particular environmental and fisheries sensitivity.
If a port or statutory harbour considers it necessary to include dispersant use as a
strategy then it can apply for a standing approval from the licensing authority. Thisestablishes a permission which allows the use of an appropriate quantity of a
specified dispersant product on a spill without having to seek specific Licensing
Authority approval at the time of the incident. This is designed to facilitate rapid
response to a minor spill in areas where there are no special environmental
sensitivities.
In order to obtain a standing approval, a request must be made in writing to the
Licensing Authority at the same time as a draft oil spill contingency plan is submitted
for agreement.
Any dispersant products held in stock (whether by commercial organisations or
government stockpiles) must be tested for efficacy at the appropriate intervals.

Toby Stone - Maritime and Coastguard Agency

Page 5

The Operational Use Of Dispersants in the United Kingdom

PAJ Symposium, Tokyo, February 2004

If dispersant has been transferred from the manufacturer’s packaging (e.g. poured
from the drum into a bulk tank on a vessel) then it must be retested for efficacy every
5 years after manufacture. If the dispersant remains sealed in the manufacturer’s
original packaging then the retesting can be delayed but must be carried out after 10
years and thereafter every 5 years.
Approval of a dispersant productThere are several issues to address when considering the approval of a dispersant
product for use under the licensing regime. These include two main areas; the testingof a dispersant’s specifications and effectiveness, and secondly testing a dispersant
for toxicity.
Dispersants are tested for conformity to a number of attributes. These include
dynamic viscosity, flash point, cloud point, miscibility and efficiency. The efficacy test
assesses the proportion of the total volume of oil treated that is dispersed into thewater column.
There are two toxicity tests. The first ensures that the relative toxicity of anoil/dispersant mix is no greater than the toxicity of the oil alone (Sea Test using thebrown shrimp Crangon crangon). The second ensures the toxicity of dispersant alone
is not greater that the toxicity of the oil alone (Rocky Shore test using the common
limpet Patella vulgata). All dispersants must initially pass both tests and any further
reapproval or rebranding.
The recent UK sea trials
As stated previously the UK has used a dispersant based capability for many years.
Backing up this requirement have been many sea and laboratory trials. The recent
sea trials off the Isle of Wight, United Kingdom are typical of such on-going trials. The
UK is fortunate in that it is still possible to conduct such trials under very strict
controls. In many parts of the world now this is no longer the case.
Many studies of oil spill dispersant effectiveness have been conducted around theworld using a variety of laboratory test methods in recent years. The results fromthese laboratory tests indicate that the viscosity of spilled oil, together with several
other factors, influence the effectiveness of oil spill dispersants. Higher viscosity oils
are generally more difficult to disperse than lower viscosity oils, particularly after
emulsification.
The relationship between dispersant effectiveness and oil viscosity is not linear.
There appears to be a narrow range of viscosity value which, when exceeded,
prevents dispersants from being effective. However, this limiting oil viscosity varies
with different test methods. While, it is reasonable to suppose that different laboratory
test methods represent, to some degree, different sea states, this cannot be provensince no laboratory test method is an accurate simulation of the complex mixing
processes that occur at sea.
The results from laboratory test methods give good relative results; the effect ofdifferent dispersant treatment rates and differences between the effectivenessachieved on various oils by different brands of oil spill dispersants appear to besignificant. However, the results from laboratory test methods cannot be translated in
an absolute way to likely performance of dispersants on spilled oil at sea. This can be

Toby Stone - Maritime and Coastguard Agency

Page 6

The Operational Use Of Dispersants in the United Kingdom

PAJ Symposium, Tokyo, February 2004

a major disadvantage when using the available information to plan for the operationaluse of oil spill dispersants.
The methodology
The sea-trials attempted in part to provide a ‘calibration’ of existing laboratory test
results to dispersant performance at sea. These sea-trials differed from previous
studies conducted at sea using different viscosity levels and particular dispersantsand dispersant treatment rate to create a matrix of dispersant performance.
Previous sea trials had used a limited number (from 2 to 5) of slicks of relatively large
amounts (10 to 50 tonnes) of test oils. In contrast, the 2003 sea trials had thepotential to use combinations of 4 oils, 3 dispersant and 3 dispersant treatment rates
to produce 36 test oil slicks of much smaller volumes of 10 or 20 litres.
The 4 test oils used were IFO-80, IFO-120, IFO-180 and IFO-380 fuel oils. IFOs
(Intermediate Fuel Oils) are graded by their viscosity at 50ºC; IFO-180 has aviscosity of 180 cSt at 50ºC.
Unlike crude oils IFO properties do not change rapidly when spilled on the sea, they
are readily available and do not require special shipment conditions due to their low
flash point. IFO-180 and IFO-380 are the typical HFOs (Heavy Fuel Oils) that are
carried as ships bunkers in medium to large ships.
The 3 oil spill dispersants used were Agma Superconcentrate DR379, Corexit 9500
and Superdispersant 25. These three dispersant represent 60% of the UK
government stockpiles. Corexit 9500 is not on the UK approved dispersant list, but isavailable in other parts of the world and has been extensively studied in laboratory
tests. However existing government stocks of this product can still be used.
The 3 dispersant treatment rates used were DORs (Dispersant to Oil Ratios) of 1:25,
1:50 and 1:100. A DOR of 1:25 is the typically recommended dispersant treatment
rate, but some laboratory studies have indicated that dispersants could still beeffective when used at the lower treatment rates. Since this would yield significant
cost savings and operational advantages, DOR was included as a variable.
Minimising dispersant quantity used whilst achieving optimal dispersion may further
reduce overall environmental impact.
Oil release and dispersant spraying was carried out from the barge Willcarry. Oil Spill
Response Limited (Southampton) with the assistance from Briggs Marine
Environmental Services (Aberdeen) provided the technical and operational capability
to deliver this.
Test oils were laid down onto the sea as a 20 metre long strip through a Delta typeskimmer head as the barge sailed directly into the wind at two knots. Dispersant was
sprayed at the required rate onto the oil layer shortly after it was deposited on thesea. Some UVF (Ultra Violet Fluorometry) to measure dispersed oil concentrations
was carried out from a small boat at one metre depth.
The main method of assessing dispersant effectiveness was by visual observation bya panel of experts including representatives from CEFAS, CEDRE, ITOPF, MCA and
OSRL. A Coastguard boat and a chartered diving boat provided the platform forthese experts and other observers to the trials. All test runs were coded andrandomised so that the precise combination of oil, dispersant and treatment rate was
unknown to the experts and observers.

Toby Stone - Maritime and Coastguard Agency

Page 7

The Operational Use Of Dispersants in the United Kingdom

PAJ Symposium, Tokyo, February 2004

The experts used a standardised reporting form, specifying the degree of observed
dispersion, and other effects, on a four-point scale which comprised; not occurring or
not obvious; slow and partial dispersion; moderate dispersion; rapid and total
dispersion.
The dispersion can be reliably observed by visual means, provided that the observeris close to the treated oil when subjected to wave energy. There are several visualclues that dispersion is occurring; the most obvious is that the water in the wave crest
appears brown or black, rather than clear, because of the dispersed oil. Anothervisual indication is the presence of individual dispersed oil plumes that can be briefly
seen as the cresting wave temporarily removes the surface oil slick.
The matrix approach to these sea trials ensured that all possible degrees ofdispersion, from ‘no dispersion at all’ to ‘total and rapid dispersion’ would occur atdifferent oil / dispersant brand / dispersant treatment rate combinations. The selected
test sequence ensured that observers would be able to observe a wide range ofdispersant performance. Subsequent analysis of the results from these sea trials
showed that the 6 or 7 expert observers independently, and without discussion,
recorded very similar observations.
rdth

The sea trial was intended to be held over 3 days; Monday 23 to Wednesday 25
rdJune. The sea was too rough for testing on the 23 with wind speeds gusting to 28thknots. The sea was too calm for testing on the 24 due to a total absence of crestingthwaves. Testing with IFO-80 began on the 25 , but abandoned for safety reasons as
the wind speed exceeded 20 knots by midday.
thth

Testing took place on Thursday 26 and Friday 27 June with wind speeds varying
between 8 and 14 knots. A reduced test programme was carried out because of thedelay caused by the unsuitable sea conditions. Tests concentrated on using IFO-180
and IFO-380 since early tests showed a clear distinction in dispersant effectivenessbetween these two oils.
Initial results
The initial results were interesting. At this stage the report is draft and requires further
analysis. As such I will make no reference to dispersant brand types. I cansummarise the results as follows:?? The IFO-180 fuel oil used in these tests (which had a viscosity of
approximately 2,000 cP at sea temperature) was rapidly and totally dispersedby one dispersant at 12 knots wind speed when applied at a DOR of 1:25.
The two other dispersants were not as effective but still caused a reasonable
degree of dispersion of IFO-180 fuel oil.
?? At lower wind speeds of 7 – 8 knots one dispersant at a DOR of 1:25 was lesseffective, but still caused moderately rapid dispersion of IFO-180.
?? The IFO-380 fuel oil used in these tests (which had a viscosity of 7,000 to
8,000 cP at sea temperature) was not rapidly and totally dispersed by any of
the three dispersants when used at treatments rates ranging from DORs of
1:25 to 1:100.

Toby Stone - Maritime and Coastguard Agency

Page 8

The Operational Use Of Dispersants in the United Kingdom

PAJ Symposium, Tokyo, February 2004?? At wind speeds of 13 - 14 knots with the associated increase in wave energy,
the performance of two dispersants used at a DOR of 1:25 improved to
produce moderately rapid dispersion of IFO-380. The other dispersant was
not so effective.
The results are still being analysed, compared with laboratory test results and acomprehensive report including photographs of the sea trial is being written.
Initial conclusions
Some of the initial conclusions can be summarised as follows;?? All three dispersant brands tested achieved more than the minimum requiredin the Warren Spring Laboratory (WSL) efficacy test, but they showedsignificant differences in performance at sea. The performance of a particularbrand of dispersant at sea is a function of oil viscosity, dispersant treatment
rate and prevailing wind speed linked to fetch and sea state.
?? The IFO-180 fuel oil used in these tests could be totally and rapidly dispersedby one dispersant used at a DOR of 1:25 at 12 knots wind speed. The othertwo dispersants were somewhat less effective, but still caused moderate
dispersion when use at a DOR of 1:25.
?? The IFO-380 fuel oil used in these tests (which had a viscosity of 7,000 to
8,000 cP at sea temperature) was not rapidly and totally dispersed by any of
the three dispersants when used at treatments rates ranging from DORs of
1:25 to 1:100 at wind speeds of 7 – 9 knots., but moderate dispersion wasachieved with two of the dispersants used at a DOR of 1:25 at wind speeds of
13 – 14 knots.
Summary points
In summary the following should be considered;?? The sea trials have shown that the amount of wave generated mixing energy
is a particularly important aspect for the successful dispersion of relatively
high viscosity oils. It has long been known that the rate of enhanced
dispersion of dispersant-treated, initially low viscosity crude oils significantly
increases when a significant amount of breaking wave action is present.
?? It should be noted that the different grades of IFO fuel oils were not taken as
being typical or representative of all fuel oils of these IFO grades, since HFOs
vary very widely in properties such as Pour Point.
?? With the factor of wind speed there appears to be a more marked effect withthe higher viscosity IFO-380 fuel oil used in these sea trials. There is sometransition from very little dispersion at 7-9 knots wind speed, through tomoderate dispersion at 12 to 13 knots. This trend may continue, so that there
would have been rapid dispersion of the IFO-380 fuel oil at 20 knots or higher
wind speed. Unfortunately, although such higher wind speeds wereencountered during the intended test period, it was not safe to proceed withthe testing which involved relatively small boats that were 10 nm offshore.

Toby Stone - Maritime and Coastguard Agency

Page 9

The Operational Use Of Dispersants in the United Kingdom

PAJ Symposium, Tokyo, February 2004?? It seems very likely that spilled oils with a similar viscosity to that of the IFO380 used in these sea trials (7,000 – 8,000 cP at sea temperature) could be
rapidly dispersed at winds speeds higher than 13 knots, but below theoperational limit of 30 to 37 knots.
?? The sea trials were conducted with freshly spilled fuel oils; there was no timefor evaporation or emulsification to occur before the oils were sprayed withdispersant. This was an intentional element of the experimental design andwas used to limit the number of variables being studied.
?? Dispersants that all achieve the minimum efficacy level in the WSL test for
Defra approval purposes are not equivalent in their performance with oils atsea.
?? The sea trials demonstrated that there are significant differences between theperformances exhibited by different dispersant brands.
?? Prior to the trials it had been considered by some that certain dispersant
brands were considered very much more effective in treating heavy fuel oils.
The trials did not confirm this. However, the trial results still did indicate
certain dispersants were slightly more effective at dispersing the IFO-380, butthere is insufficient data to tell whether this is significant or not.
?? Any operational use of dispersants has to use nominal dispersant treatment
rates; the amount of spilled oil is rarely known and the oil slick varies greatly
in thickness from place to place. Experimental design features ensured that
all the test oils were sprayed more accurately with dispersant than could everbe achieved at a real oil spill.
?? In most laboratory test methods, the required amount of dispersant can be
added very evenly and precisely to the test oil. The dispersant is added dropwise to a confined area of oil and is allowed to soak in before the treated oiland seawater are mixed. Some of these test results have indicated that somedispersants can be effective on some oils at a treatment level of a DOR of
1:100 or even 1:200. If dispersants could be used effectively at a quarter orone-eighth of the recommended treatment rates, there would be significant
savings in cost and operational complexity.
?? The results from these sea-trials show that there is the expected effect ofdispersant treatment rate; less dispersant is less effective.
?? Very low dispersant treatment rates of 1:100 or less are not practical whendispersants are used outside of laboratory tests. The dispersant losses
caused by wind-drift and the inaccuracies encountered during any dispersant
spraying operation at sea mean that greatly reduced treatment rates cannot
be recommended for dispersant use.
The way forward
The trials were successful due to the overwhelming support and co-operation from
regulators, moderators, responders and industry. A common objective was sought
and achieved. It is hoped that further trials will be carried out using this very
successful collaborative approach.

Toby Stone - Maritime and Coastguard Agency

Page 10

The Operational Use Of Dispersants in the United Kingdom

PAJ Symposium, Tokyo, February 2004

From an operational perspective the door has been opened with regards the use ofdispersants for higher viscosity oils. The trial has clearly indicated that certain IFO 380 products could be dispersed using an appropriate dispersant at a high treatment
rate with acceptable environmental and energy conditions.
Any future response in the UK will always start with a trial spray from an aircraft or
surface vessels with an appropriate monitoring regime.
UK dispersant resources
The Tricolor incident is one such example of the use of dispersants at sea. This car
carrier capsized to the north of the Dover Straits. An accidental release of IFO–380
when a barge rammed the ship led to an International effort to attempt a test spray of
the released oil. Belgium and France agreed to the use of the UK dispersantresources for a test spray. However, due to a low cloud base the attempt wasaborted. It does however indicate a step change in policy for countries now
considering the use of dispersants.
The resources that were planned to be used including the MCA contracted Cessna
406 aircraft with composite spray pod. This can fly at 130 knots from a height of 30
feet and is able to deliver up to 1.5 tonnes of dispersant. It also has a night time
capability. This is usually the resource for conducting a test spray.
Also under contract to the MCA are two Lockheed Elektra aircraft modified fordispersant spraying. Each can deliver up to 15 tonnes of oil dispersant at very low
level. Both are required to be at the nominated forward operations base loaded withdispersant and ready to spray.
Both dispersant spraying aircraft have to be operationally supported by a surveillance
aircraft. The MCA have two contracted aircraft, a Cessna 404 and a Cessna 406.
Both are on 30 minutes readiness by day and two hours by night. All of the aircraft
contracts are with Air Atlantique Ltd, Coventry.
To support the aircraft, dispersant stockpiles are located in eleven locations. There
are seven different types with a total of 1500 tonnes.
Some ports and harbours also have a dispersant capability usually using surface
craft, for example tugs. This includes a standing approval mentioned previously inthis paper.
The Offshore industry has a substantial capability through local regional and national
resources from surface stand by and supply boats with pre-fitted spray equipment
and dispersant. In addition all operators have contracts with tier three providers forexample Briggs Marine Environmental Services and Oil Spill Response Ltd. This
includes the Aerial Dispersant Delivery System (ADDS Pack).
At the start of this paper reference was made to some incidents specific to the UK
and how the UK has suffered three of the top twenty spills as categorized by ITOPF.
It is very interesting to note that 50% of spills in this ITOPF top twenty list occurred inEuropean Commission waters. This is an unfortunate statistic.
The recent ERIKA and PRESTIGE incidents have raised the profile of such tanker
incidents. The various Erika packages (linked to the Erika disaster) and associatedEuropean Directives have far reaching consequences.

Toby Stone - Maritime and Coastguard Agency

Page 11

The Operational Use Of Dispersants in the United Kingdom

PAJ Symposium, Tokyo, February 2004

Incidents involving very large tankers appear to be on a downward trend. The
International Tanker Owner’s Pollution Federation (ITOPF) and the Advisory
Committee on the Protection of the Seas (ACOPS) statistics confirm this trend.
Bunkers though are increasingly a threat. Some of the medium sized ships cancarrier substantial quantities of bunkers.
The KODIMA is one such example. This timber carrier grounded in severe gales inCornwall, SW England last year. There was pollution, principally from the timber deckcargo lost and jettisoned overboard in an attempt to stop the ship listing in thehurricane force winds. This was not a national incident but still posed a threat ofsignificant pollution. A successful salvage operation under the overall control of
SOSREP, supported by the MCA, minimised the release of bunkers.
So the risks are not just limited to tankers. The UK has dealt with other recent
incidents where the threat of pollution was from the ships bunkers and notnecessarily from the cargo. To have an effective response to any given incident you
need to consider all available strategies. This includes options for a mechanical,
dispersant and leave it alone strategy.
The UK is very fortunate in that it is part of a very developed and effective OPRC
regional agreement through the Bonn contracting parties. The resources of Bonnoffer a powerful arsenal in the fight against any forms of marine pollution.
There is always a temptation to concentrate on oil pollution but marine pollution
covers the majority of substances. The new HNS (Hazardous & Noxious Substances)
Convention and the OPRC-HNS protocol should address this. The UK does not needreminding about the threats posed by HNS cargoes. The Ievoli Sun sank in the
English Channel recently with Styrene, Methyl-Ethyl-Ketone and Iso- Propyl Alcohol.
Most of the pollutants were recovered over a period of 6 months.
In summary the UK has dealt with the full gambit of incidents ranging from capsizedfishing boats in the vicinity of fish farms, cargo ships with substantial quantities ofbunker fuel oil, HNS incidents affecting both land and marine pollution, to very large
tankers with hundreds of thousands of tonnes of crude oil on board.
Each incident is different. The UK has a highly developed prevention andpreparedness strategy for these types of incidents. The primary prevention tool in the
UK is the four emergency towing vessels in the UK. This is linked to a robustcommand and control system linked to places of refuge for ships in distress and the
SOSREP function.
Hopefully the dispersant capability will never have to be used. The MCA is notcomplacent though. The risk remains in both UK and all European waters. The UK
National Contingency Plan is a living document. There will undoubtedly be future
incidents with associated outcomes, lessons learnt and recommendations. These will
have to be taken on board and further enhancements and adjustments made to the
National Contingency Plan.
And finally the Maritime & Coastguard Agency vision,
SAFER LIVES, SAFER SHIPS, CLEANER SEAS

Toby Stone - Maritime and Coastguard Agency

Page 12

The Operational Use Of Dispersants in the United Kingdom

PAJ Symposium, Tokyo, February 2004

References
UK National Contingency Plan
IMO OPRC Convention
Oil Pollution Act 1990
IMO Bunker Convention
IMO HNS Convention
IMO HNS-OPRC protocol
Safer Ships Cleaner Seas, Lord Donaldson
Salvage and Intervention and their Command and Control, Lord Donaldson
MAIB Sea Empress Inquiry
Merchant Shipping Act 1995 (as amended)
Merchant Shipping Maritime and Securities Act 1997
Maritime Safety Act 2003
Statutory Instrument No.1056 OPRC 1998
Contingency Planning for Marine Pollution Preparedness and Response, MCA
UK Emergency Towing Review, MCA
Web Sites
MCA http://www.mcga.gov.uk
IMO http://www.imo.org/home.asp
DEFRA http://www.defra.gov.uk/environment/marine/oilspill/default.htm
DfT http://www.shipping.dft.gov.uk/index.htm
Bonn Agreement http://www.bonnagreement.org/
Environment Agency http://www.environment-agency.gov.uk/
English Nature http://www.english-nature.gov.uk/
Scottish Environment Protection Agency http://www.sepa.org.uk/
Joint Nature Conservation Committee http://www.jncc.gov.uk/default.htm
Countryside Council for Wales http://www.ccw.gov.uk/
Department of Trade and Industry http://www.dti.gov.uk/
BOSCA http://www.maritimeindustries.org/
Nautical Institute http://www.nautinst.org/
International Tanker Owners Pollution Federation Ltd http://www.itopf.com/
UK Offshore Operations Association http://www.ukooa.co.uk
ACOPS http://www.acops.org/

Toby Stone
Head of Counter Pollution & Response
Maritime and Coastguard Agency
United Kingdom
January 2004

Toby Stone - Maritime and Coastguard Agency

Page 13