Oil spillages in one form or another have been with us since the early days of the Industrial Revolution and probably always will be so long as homo sapiens continue to be thoughtless, careless, or downright unlucky. Spillages occur in almost limitless variety and there are no doubt numerous methods by which they can be classified or categorized but for the practical purposes of those charged with the duty of clearing them up, much is the simplest is to distinguish between those in which primary consideration is recovery of the oil for re-use and those in which the sole, or at least the main, aim is removal of the pollutant as quickly and efficiently as possible.
The majority of incidents on land and on inland waters involve small amounts of oil. For recovery to be economically viable oil needs to be present in large quantities it follows that most spillages will fall into the second category, i.e. removal as rapidly as possible will be the most dominant factor.
It is as well to keep this quite simple factor in mind when considering the subject of oil pollution as most of the anti-pollution equipment currently on the market-ranging from simple weir type skimmers to relatively sophisticated endless belt, plate and rope mop pick up devices-is designed primarily for recovery.
There can be no one piece of equipment suitable for use in all types of oil spill incident but is at least possible to set out some basic criteria:
1) It must be efficient. Efficient, that is, not only in ideal test conditions or in demonstration, but also in real life. This means, as often as not, on a cold wet Sunday in January, at the end of a muddy track and on the wrong side of a ploughed field.
2) It must be easily portable, oil spillages have a perverse tendency to occur in spots well away from convenient roads.
3) It should be suitable for use by untrained staff and able to withstand rough handling
4) Unless one is the privileged possessor of a large anti pollution budget, it should be versatile, suitable for use with oil of all types and in the widest possible variety of situations.
5) Absorbents are easily and safely disposable-non toxic and incinerable.
6) Machinery is easy to clean and use.
Oil On Flowing Water
Spillages of this type are generally the most difficult to deal with, especially in wide rivers or flowing streams and/or in windy conditions. There are two priorities; first the source of the pollution should be identified and if practicable, shut off or isolated. Second, but of equal importance, the oil already spilled must be contained.
If the source of the leakage cannot be shut off, absorbent booms should be deployed at the outlet. Alternatively, cushions must be used if the outlet was a deep, narrow drain or gully.
For containment purposes, booms, strung together if necessary to form a continuous barrier of the required length, should be deployed and secured to suitable points on both banks.
In last flowing current it may be necessary to let the boom drift downstream to reduce relative speed, at the same time endeavouring to work the oil into slack water.
Absorbent booms should be deployed in pairs, one in front of the other and the second acting as back up. In this way, when the upstream boon is fully saturated with oil, it can be removed and replaced without the risk of oil escaping.
In wide rivers, and especially when there is a fast flowing current, it may also be necessary to use a larger containment boom with ‘skirts’ to prevent oil being drawn downwards beneath the absorbent barrier. In such cases, the absorbent booms should be located downstream of the larger boom.
It may also be advisable to supplement the booms with loose particulate or pads. This not only provides additional protection but also speeds up the absorption process. The pads are easier to harvest than loose particulate, which needs a wire rake or specially designed scoop but the particulate is unequalled for absorbing oil trapped in odd corners such as the angle between two joined booms or between boom and bank.
Depending on the extent of the pollution, oil trapped by the booms can be left for the absorbent process to take its course, with boom lengths renewed at appropriate intervals and the oil removed by absorbent sweeps manoeuvred from the banks or taken up with skimmers, vacuum suckers or other pick up devices.
Where tide or abnormally high water level has left deposits of oil on the banks of streams or rivers, rolls of absorbent can be trimmed as necessary and placed over the polluted area to absorb and prevent the spread of contamination.
It is worth noting that the bright banks of colour often visible on the surface after a spillage are microscopic in thickness and will usually disappear quite quickly in fast flowing water once the source of the pollution has been isolated. If however this rainbow sheen needs to be removed for cosmetic purposes, sweeps can be used to give the surface a final clean up.
Spillage On The Ponds And Lakes
In still or slowly flowing water the same general principles of location of source, isolation and containment with apply. Containment will of course always be easier in these conditions and there will rarely be need to employ a containment boom except possible as a concentrator where skimmers are being used to remove a large spillage.
Except where there is a serious risk to fish or bird life, there will generally be more time to take remedial measures. It is however important to ensure that any outlets from the pond or lake are protected by absorbent booms – or pillows in the case of deep drains or gully’s – to avoid the risk of pollution spreading to nearby streams or watercourses. Such measures should be taken even if no flow is visible at the time of the incident. Rainfall or any other sudden ingress of water can quickly raise the water level and produce an outflow.
Often the absorbents can be left to do their work unaided in these conditions but with no flow to disperse it oil is more likely to be present in recoverable quantities and the use of skimmers or other devises – in any case much more effective in still water – is more often justified.
In still water any rainbow sheen will talk longer to disappear at is presence may in any case be unacceptable in ornamental lakes, etc. Sweeps, pads or loose particulate can all be used very effectively in still water, the final choice depending upon the size of the polluted area.
Spillage On The Highway
This is a frequent occurrence, usually following accidents involving tankers or multi vehicle pile-ups. Other causes, including leakage from parked vehicles and of the road accidents where the resultant spillage spreads to the highway. Here absorbents play very much the major role.
Once the affected stretch of roadway had been close to traffic - normally a police reasonability- containment becomes the first priority. If sufficient had been spilt, oil in the carriageway can be enclosed with booms and absorbent by loose particulate, pads or rolls. Most commonly, loose particulate alone is used, sometimes kept in position by a top layer of sand. Two or more applications are normally necessary before all significant traces are removed from the road surface. Rapid absorption of oil will prevent deterioration of tarmac surfaces.
To prevent run off from the road into the drainage system, booms – or where appropriate pillows – are deployed in all connecting drains and gutters. Where the outflow is into open ditches, back up booms should be located at inlets and at any potentially vulnerable adjoining streams or brooks.
Where damaged vehicles continue to leak, pillows, pads or rolls are used to prevent oil from spreading by absorbing the leakage at source. Secured beneath the site of the leak pillows are also an effective means of preventing oil spilling where a damaged vehicle is driven or towed away.
Finally, rolls of absorbent are used to protect nearby areas from pollution caused by spray of passing vehicles and foot traffic.
Responsibility for spillage on the highway normally falls to the Fire Service, Police and an approved contractor, both of whom work in conjunction with the Regional Council where contamination of water is likely.
Spillage In The Workshop
In the factory environment as elsewhere prevention is infinitely better that cure. Placed beneath pump glands, pipe joints, hose unions, drip trays and other likely sources of leakage, pillows, pads and rolls can all be used to deal with pollution at source.
Sensible housekeeping can also help. For example, even small quantities of spent oil should not be left outside in open drums. The drum fills with rainwater and it is the oil in the surface that spills over. Careful indoctrination at all levels can sometimes bring gratifying for quite small effort.
For patches of oil spilt on the workshop floor loose particulate is usually sufficient – sprinkled on and brushed or scooped up when saturated. Pads can be used in the same way with the additions advantage that can also be employed as absorbent wipes in damp or humid conditions.
Rolls are used to protect large areas –walkways, entrance halls, stairs, doorways, etc, from the spray of high speed machinery and contamination by foot traffic – (where there is a heavy foot traffic of excessive wear mats can be put down to avoid scuffing, etc).
Where leakage from industrial buildings could lead to pollution of waterways, streams, etc, through penetration of ground water, booms should be placed at outlets and at the entrance to vulnerable drains. Depending upon the location, pillows and pads can be employed in the same way.
Oil in factory sumps, inspection pits etc is best dealt with bye pillows or pads or by loose particulate if the quality of oil is small.
Oil Storage Tanks- A careful check should be made of valves and the bunds in which they stand, from which water should be regularly drained following removal of oil.
Oils In Docks and Harbours
Oil spills in docks and harbours are among the most frequent incidents of all and can often present a considerable problem especially in adverse weather conditions. The use of the specially formulated oil dispersant employed in the open sea is seldom practicable or desirable and absorbents often represent the only answer – even though complete removal is rarely possible.
Absorbent booms strung together are used to minimize the effect of spillage when ships are bunkering or handling oil cargoes, supplemented where necessary bye cushions or pads. The use of large containment booms will sometimes also be advisable.
Loose particulate is an effective means of dealing with small amounts of oil in the corners of docks, lock chambers etc as well as removing oil spilt on quaysides, slipways, steps, etc. Absorbent pads are employed in the same way while absorbent rolls are useful for protecting large areas of dockside when pollution is considered likely.
On Board Ship
Once oil has spilled over the side at sea, dispersant is generally considered the most satisfactory but absorbents still have an important role to play on board ship, particularly in pollution prevention.
Pillows or pads placed beneath or around pumps, compressors, generators, pipe manifolds etc will absorb any leaked oil and allow any water to pass through into the bilges unpolluted.
Pillows are extensively used in bilges and slop tanks where they can be left for extended periods to collect surface oil. These are then changed over when saturated.
On deck, both pillows and booms are deployed to cover scuppers and outlets to prevent oil, from running overboard as well as beneath deck machinery to deal with leaks and prevent any spills from spreading. Pads can be used in the same way and also serve as absorbent wipes for swabbing down machinery. Mats should be deployed in walkways particularly during dry-docking as oil may be spread to accommodation, etc.
Water Cooled Piston Fuel Valve Cascade Tanks – Cushions placed in cascade tanks absorb any oil present. The cushions are then changed periodically dependent on total amount of contaminate.
Interceptors, Sumps etc
In static installations such as interceptors, sumps and the bunds around tank farms removal of leaked oil with seldom be a matter of urgency unless there is a risk of overflow. Where space allows, skimmers are often used and on larger installations where oil is always present regular visits are make by vacuum suckers. Nevertheless, for most installations absorbent cushions are the simplest and cheapest solution. This is particularly true in interceptors where access is usually via a manhole.
Using a retaining rope, pillows are simply lowered into the pit and left to float, continually absorbing oil until saturated. Where oil occurs regularly, pillows can be replaces in a systemized weekly or monthly basis. In open sumps, a final polish can be applied with loose particulate or pads.
Railway Depots and Station Areas
Oil spills in the railway industry are normally the result of overfilling the diesel tanks, numerous and constant drips from diesel propelled vehicles, maintenance machinery dripping or spillage whilst refuelling from 45 gallon drums. The result is a highly dangerous working environment plus unsightly station areas, poor ballast formation and constant pollution of nearby watercourses.
Some common applications include:
Pillows – In sumps, inspection pits, trackside gully's, drains.
Booms – Floating in large sumps, interceptor pits, drainage holding areas adjacent to lakes or rivers.
Trackmats for use in the four foot, sleeper ends, between tracks, station concrete aprons, fuelling depot aprons, and track where diesel propelled units are standing in stations or signal halts foul the ballast.
Pads and Rolls for cleaning down machinery around fuel pump pipes and sumps in workshops, track maintenance repair shops, and repair depots, also inside wagons to ensure slip free surfaces.
Emergency Oil Spill Response
A 24 hour around the clock service is available throughout New Zealand provided by a number of companies. All contractors will require a signed order or permission before commencing work. This order will normally incorporate the terms and conditions on which the work will be performed and in addition the payment terms, a price list showing the charges for labour and materials, mileage etc. If the original job is expanded in anyway a new order should be secured. This should eliminate problems concerning the assessment of costs and ensure early payment.
It is however crucial to ensure that only reputable companies are engaged to perform Spill Response tasks. These companies should have as part of their ensemble:
• A full range of absorbents, including particulates
• An approved remediation product
• A reliable hazardous information data-base
• Approved personal protective equipment
• Approved tools such as brooms, spark proof shovels and approved
containers for disposal of contaminated substances and sorbets.
• A schedule of contractors to perform additional tasks.
In depth detailed literature on each product is available on request.