Last year in the latest of a long line of criminal cases, a Cyprus-based shipping company was fined $2 million for concealing discharges of oily water into the Atlantic. The Chief Engineer was sentenced to a fine of $3,000 and placed on probation for two years. As with all these cases, the conviction was not for the incident itself but for falsifying oil record books to conceal it.
By far the majority of legal actions occur in the US but illegal practices discovered are probably just the tip of the iceberg. Only around one in ten ships afloat will ever call at a US port and many of those that have made illegal discharges will not be caught. Therefore it can be surmised that the number prosecuted probably amounts to less than one in hundred.
The root cause for illegal discharges is a combination of the workload involved maintaining ineffective treatment systems and the expense of disposal of oily waste ashore. The latter is an incentive for owners to condone overboard discharge and in some cases even demand it. However, deliberate disposal of oil at sea is rightly condemned as a criminal practice especially when performed by professional seafarers.
Keeping it clean
On most ships the oil involved comes from the machinery space bilges or could even be fuel oil that is for some reason unsuitable for use, oily mixtures of hydraulic fluids and lubricants from hatches, cranes and other equipment. MARPOL’s test and performance requirements are that any mixture of water and oil should be treated by oily water separating equipment before the waste oil is returned to sludge tanks and the cleaned water allowed to be discharged to sea.
Regulations in MARPOL against discharging untreated oily bilge water date back to 1992 when a limit on the oil content allowed in water from an oily water separator was set at 15ppm. A revision in 2003 was adopted as MEPC 107(49) and apart from some amendments in MEPC 285(70) is still the main regulatory text.
The 2003 revision was to tackle the subject of emulsions which some early oily water separators were very bad at dealing with. There are still many of the older separators still in existence but gradually their numbers are diminishing as ships reach the end of their life. Most manufacturers have modified or improved their machines to meet the new performance standards.
Improving pollution prevention equipment
When separator performance standards were so poor, and the routine maintenance needed to keep them running was seen as dirty and a waste of time, it was possible to have some sympathy for the crew involved. That is less likely to be the case these days except in poorly maintained vessels.
It is true that the type approval testing process – even as laid down in MARPOL today – is flawed in that it takes little account of the dynamic movements such as heave and pitching and rolling of ships at sea and the effect on separators. There is a requirement for separators to operate reliably at an inclination of 22.5° for a certain period but this is still a static test and in practice the ship could be constantly moving in several planes simultaneously. The performance standards do also attempt to mimic some other environmental aspects including vibration and extremes of temperature.
Although manufacturers of other separator types may disagree, the centrifugal type separator is claimed to have an advantage in extreme operating conditions. This is because the gyroscopic effect of the liquid circulating at high speed inside the separator will to some extent offset pitching and rolling of the ship.
Despite the difficulty in obtaining the 15ppm performance standard, some more enlightened operators impose on themselves stricter requirements for separation by opting for a class society’s ‘Green’ or Clean notation. The approval requirements then shift to just 5ppm for oil in water – a performance standard mandated in the Great Lakes. When type-approval testing to this performance requirement, class societies generally make use of the same testing specifications as laid down in IMO resolutions. At least one (DNV) does however require that “the 5ppm bilge water separator must be designed to operate in each plane that forms an angle of 22.5 degrees with the plane of its normal operating position”.
When operating at maximum capacity on a poorly maintained separator, the 15ppm bilge alarm is likely to be constantly sounding and initiating the automatic stop mechanisms. Addressing this and ensuring sufficient spares and consumables are supplied could likely eliminate most problems.
An engineer faced with a machine where the alarm and stop mechanisms cut in frequently may come to the conclusion the oil content meter is faulty but since it is not easily over-ridden or able to be ignored may lose patience and reach for a magic pipe. One possibility that should not be overlooked is that the OCM needs to be recalibrated.
Recalibration can cut costs
MEPC.285(70) sets out that the validity of calibration certificates should be checked at IOPP annual/intermediate/renewal surveys. The accuracy of 15 ppm bilge alarms is to be checked by calibration and testing of the equipment conducted by a manufacturer or persons authorized by the manufacturer and should be done at intervals not exceeding five years after its commissioning, or within the term specified in the manufacturer’s instructions, whichever is shorter.
Alternatively, the unit may be replaced by a calibrated 15 ppm bilge alarm. The calibration certificate for the 15 ppm bilge alarm, certifying the date of the last calibration check, should be retained on board for inspection purposes.
Some alarm manufacturers supply the calibrated units for crews to exchange. A spare kept onboard will allow the separator to continue to be used rather than waiting for a service engineer visit for recalibration. In either case, the cost involved is minimal compared to the level of fines meted out by courts.