3.31 SPILLS AND OVERFLOWS
Good planning and careful attention to the basic precautions of safe
loading will prevent most spills or tank overflows from occurring. However,
there will occasionally be errors or mechanical failures which cause
cargo to escape onto the deck, into the pumproom, or into the sea. The
size of the spill will be directly related to the inattention of the
cargo watch. If the pumproom is not being carefully monitored, large
areas of deck are left unobserved, or the cargo watch officer is absent
from the CCR/deck for an extended period, then there is an excellent
opportunity for a large spill.
3.31.1 Spill containment installations
Some spill containment preparations begin on the drawing board of the
tanker designer, or must be added by conscientious owners if absent
from the original design:
- Gutter bars of sufficient height must be provided along the main deck
gunwale, separating the main deck from the aft deck and around the aft
deck (in event of a spill while fuelling).
- The gutter bar openings and all deck scuppers must be designed so
that they can be readily closed oil tight and the closure hardware or
devices must be both easy to use and durable. Wooden plug or sliding
plate and cement closures are not effective. Expanding rubber plugs
are very effective, convenient and durable.
Portable air-powered pumps should be fully rigged
before cargo operations begins. Lash the suction hose in position
where spilled oil will accumulate. In case of a deck spill, open valve
A, then valve B.
- Spill containment tanks can be provided in the original design of
the ship, or added as a modification. They should be located at the
aft main deck on each side and fitted with a sluice opening so that
accumulations of oil can be drained into them by opening a single valve.
This valve should be left open at all times while the ship is loading
or discharging in fair weather. Transfer fittings and piping must be
provided to permit pumping of any accumulations to the slop tank.
- Provide convenient connections for compressed air and deck slop line
fittings for air operated pumps to be used to recover spilled oil from
3.31.2 Management initiatives
Many of the initiatives needed to prevent and control spills are a shipowner's
or manager's responsibility. These include:
- Provide a program of training aids to properly prepare the crew to
prevent spills or to deal with overflows and spills when they occur.
- Provide spill containment and recovery materials and equipment.
- Ensure that regular training in oil spill counter measures is regularly
performed on board and records maintained (per OPA-90 requirements).
- Provide the ship with an effective oil spill contingency plan and
ensure that agents, contractors and owner's local representatives regularly
call on the ship to discuss their roles in spill response.
- Conduct annual drills of the plan.
3.31.3 Shipboard precautionary measures
On board the tanker, the materials, equipment and plans provided by
the owner must be effectively used. Oil spill prevention measures to
be taken on board include:
- Regular training exercises in spill counter measures including when/how
to apply foam to spills, use of adsorbents and skimmers, rigging of
recovery equipment, use of spill containment
tanks, and personnel health and safety considerations when dealing with
- Verification/testing that all cargo deck drains are tightly closed
before loading begins.
- Rigging oil recovery pumps at natural spill collection points on deck
before loading begins.
- Maintaining spill containment tank sluice valves open while loading
in fair weather and closed during periods of heavy rain.
- Instructing deck watch personnel in the proper method of decanting
rain water accumulations from the deck.
- Regular inspections of the pumproom(s), all cargo deck areas and all
compartments/spaces where oil cargo could possibly leak into during
- Strict adherence to all precautions and procedures while topping off
All tanker officers should remember that only 10-15% of spilled oil
is ever recovered from the water. The best recovery technique is
still prevention! The one precaution which will contribute most
to prevention is strict adherence by all cargo watch personnel to the
When in doubt ... shut down!
3.31.4 First actions in the event of a spill
Should the unhappy event of a spill occur, the cargo watch officer must
have a checklist at hand directing his initial response until the master
or chief officer arrive to assume command. The following are some essential
initiatives. The order of execution is provisional, circumstances and
the details of the vessel's contingency plan may dictate a preferred
sequence or assign some of these actions to others who have been notified
by the ship:
- Stop loading cargo; notify the terminal to shut down and the reason.
- Open an empty tank (if available) on the same system to reduce pressure
on the tank/line which is leaking cargo.
- Sound the spill alarm on the ship, or announce it over the PA system.
All open lights should be secured when this is heard.
- Instruct the engineering watch to secure accommodation and engine
room intake fans as necessary.
- Direct the deck watch to open deck containment tanks (if not already
open), or start spill recovery pumps.
- Warn any craft alongside, instructing them to secure all sources of
- Start or request the engine room to start the fire pump (this may
be automatic on sounding of spill alarm).
- Implement the vessel's oil spill contingency plan, including notification
of coast guard, owners oil spill response contractor, and others as
- If master or chief officer are not on board, initiate the necessary
telephone calls to advise them of the situation.
- Advise the vessel's agent or owner's local representative; advising
them to notify necessary officials and mobilise the clean up contractor
- Notify the port vessel traffic service or harbour master by VHF radio.
- Advise the master/chief officer of the grade of cargo spilled and
the approximate quantity. The master's responsibilities normally include
notification of owners, technical managers, P&I Club representatives.
- Maintain an accurate record of the events and times of response actions,
but do not make any log entries until reviewed by the master.
- Ensure that crew members dealing with the spill have equipped themselves
with the proper personal protective equipment.
- No dispersants or chemical 'herders' should be used without prior
approval of local authorities.
Logbook entries and reports made following a spill incident must be
absolutely factual and truthful. An officer who has been conducting
his watch properly has little to fear from a spill inquiry and may be
confident that the facts will support him. An officer who attempts to
conceal some neglect will inevitably have his dishonesty discovered
and will be in worse trouble. The more honest the disclosure of events
and causes of a spill, the faster the event will be investigated and
disappear into the archives and the quicker the participants can resume
their normal activities.
3.31.5 Handling dangerous spills on board
Occasionally a cargo spill will be particularly dangerous because of
the low flash point and high vapour pressure of the cargo. Such cargoes
would include condensates, naphtha and gasolines. These spills are dangerous
because of the fire danger created by their uncontrolled release of
flammable vapour in confined spaces or on the open deck.
If these cargoes are spilled into the pumproom, a layer of fire fighting
foam should be applied to the pumproom bilges before any other measures
are taken. The foam will reduce the release of explosive vapour to the
atmosphere, cut off oxygen needed or combustion, and permit cargo recovery
measures to be taken in more safety.
Foam may also be applied to low flash products spilled on the main deck,
but care must be taken to avoid using so much foam or water that the
gasoline is washed over the containment.
In some cases where foam cannot be readily applied and the danger of
ignition is great, it may be better to wash the spilled cargo overboard
before it can ignite. Such a decision should be made only by the master
after carefully considering the risk of fire against the certainty of
a pollution citation.
3.31.6 Hull leaks
If cargo is seen entering the water through a hull leak, then in addition
to the actions in section 3.31.4, the cargo watch officer should immediately
take action to transfer cargo from the leaking tank. Cargo can be gravitated
or pumped to another ship's tank. If there is no available space in
the ship's cargo or slop tanks, then the cargo must be pumped ashore
as quickly as possible. These actions must not be delayed by concerns
for cargo quality or cargo contamination.
3.31.7 Master's actions
The master must be fully trained and have all necessary information,
resources and authority to respond to an oil spill by doing the following:
- Evaluate and properly assess the spill.
- Make the necessary notifications. Use IMO Resolution 680(17) content
format for notifications transmitted by telex or radio.
- Direct or cause all necessary actions to minimise, contain, or reduce
the escape of oil.
- Activate the vessel and owners 'oil spill contingency plan'.
- Request necessary outside assistance (clean up contractor).
- Maintain detailed action and event logs, having in mind the information
which will be required for spill reports.
- Follow up all actions previously ordered to ensure that they are being
properly carried out.
- Cause samples to be taken and properly labelled and stored.
- Review media training received and prepare to appropriately respond
to their questions.