Containment & Recovery
Containment & Recovery
Containing floating oil within booms for recovery by specialized skimmers is often seen as the ideal solution to a spill at sea as this aims to physically remove oil from the marine environment. As a result, it is the primary at-sea response strategy adopted by many governments around the world.
For containment and recovery of oil to be successful, there are some key challenges that must be overcome. The drifting floating oil must be located and the equipment deployed in an effective arrangement. The sea state and weather conditions must be sufficiently calm to permit the selected equipment to function well and for the response personnel to safely operate the equipment. The oil must also be in a state that is amenable for recovering using the available skimmers. These interrelated challenges commonly combine to limit the proportion of spilled oil that can be recovered to 10-15%. However, where the environment conditions and response factors allow, containment and recovery can be an important strategy.
In-situ burning is the term given to the process of burning floating oil at sea, at or close to the site of a spill. In order to undertake burning, the oil must be concentrated and an ignition source applied. Burning oil at seas has, in ideal conditions, the potential to remove relatively large amounts of oil from the sea surface.
A burn trial
The decision whether or not to burn oil at sea is often complex. The resultant fire and potentially toxic smoke has the potential to impact human health and therefore it is a technique more suitable for use offshore or away from populated areas. In Arctic regions, concern has been expressed about the potential impact of soot deposits on the rate of melting ice. The condition of the oil is also important; as the oil weathers it may lose its lighter oil fractions through evaporation and the oil may start to form an emulsion. Both these processes will make the oil more difficult to ignite and burn. Given the many factors to consider, the decision-making process for in-situ burning is best addressed during the contingency planning process.
For a successful in-situ burn the layer of oil on the sea surface needs to be at least 2-3mm thick to counter the cooling effect of the wind and sea and maintain a fuel source to the fire. Spreading of the slick means that the oil may need to be contained against a barrier. This can occur naturally against ice sheets or the shoreline, or by corralling it using fire resistant booms or 'herder chemicals.
Ignition can be achieved using a variety of devices ranging from a diesel-soaked rag to more sophisticated equipment, such as the Helitorch. This is essentially a flame-thrower which is suspended beneath a helicopter and is generally accepted as being one of the safest methods of ignition in trained hands. However, the device and experience to use it are not readily available in many parts of the world.
The state of the sea can limit the success of any burn and choppy seas may extinguish the fire altogether. Once alight, the slick itself needs to reach sufficiently high temperatures to keep the fire burning. However, as the slick becomes thinner due to the removal of the lighter fractions, the cooling effect of the wind and sea will eventually extinguish the fire.
The viscous residue that can be left following in-situ burning resembles the consistency of toffee, and can be difficult to recover. Residues also have the potential to sink and therefore may smother or be toxic to bottom dwelling (benthic) marine species. There is also the potential that residues might contaminate fishing gear.
When used appropriately, dispersants can be an effective oil spill response strategy. They are capable of quickly removing significant quantities of oil from the sea surface by transferring it into the water column where it is broken down by natural processes.
Significant environmental and economic benefits can be achieved, particularly when other at-sea response techniques are limited by weather conditions or the availability of resources. However, as with other response techniques, dispersants also have their limitations and account must be taken of the characteristics of the oil being treated, sea and weather conditions and environmental sensitivities.
How Chemical Dispersion Works
Natural dispersion of oil occurs when waves break a surface slick up into droplets that become suspended in the water column. The addition of dispersants is intended to accelerate this natural process.
Dispersants have two main components: a surfactant and a solvent. Surfactant molecules are made up of an oleophilic part (with an attraction to oil) and a hydrophilic part (with an attraction to water). The solvent transports and distributes the surfactants through an oil slick to the oil/water interface, where they reduce the surface tension and allow small oil droplets to break away from the slick. Although larger droplets may rise back to the surface, most will remain in suspension
Dispersants have little effect on very viscous oils, as they tend to run off the oil into the water before the solvent can penetrate. They are also unsuitable for dealing with viscous emulsions (mousse) or oils which have a pour point near to or above that of the ambient temperature. Even those oils which can be dispersed initially become resistant after a period of time (usually a few hours to days) as weathering processes make the oil more viscous.
In many instances, a balanced assessment of the net environmental and economic benefits of using dispersants will be necessary in consultation with national authorities, prior to application. For example, in a given spill, the benefit gained by using dispersants to protect coastal amenities, sea birds and intertidal marine life may outweigh disadvantages such as the potential for temporary tainting of fish stocks. However, for another spill scenario, the potential impacts of dispersed oil on resources such as coral reefs, water intakes, or fish spawning areas might mean that dispersant application is inadvisable.
Dispersant use can be controversial, at times generating widespread debate in the media and public forums. Whilst its use can be viewed as a way of minimizing the potential impacts of oil on sensitive resources, it is also sometimes seen as adding another unwanted pollutant into the environment that may prove toxic to marine fauna and flora.
The decision on whether or not to use dispersants is seldom clear-cut and a balance has to be struck between the advantages and limitations of the different available response options, conflicting priorities for protecting different resources from pollution damage and cost-effectiveness. Detailed contingency planning will aid in this decision process.
Biological spill oil clean up and soil Bioremediation
The underlying idea is to accelerate the rate of natural hydrocarbon biodegradation by overcoming the rate-limiting factors. Indigenous populations of microbial bacteria can be stimulated through OSEII.
The increasing number of marine oil spills asks for effective solutions for the environment. Bioremediation is a process by which chemical substances are degraded by bacteria and other microorganisms. Bioremediation techniques have become a major mechanism for removing oil residues on the affected shorelines. Among the different techniques to enhance natural biodegradation by indigenous microorganisms Since OIL SPILL EATER II (hereinafter OSE II) contains exact proportions of enzymes, bio surfactants, nutrients and other necessary constituents for complete life cycles and biodegradation that converts the waste into a natural food source for the enhanced native bacteria found in the environment. The end result of this process is CO2 and water.
OIL SPILL EATER II is not a bacteria (bug), fertilizer or dispersant product and it contains exact proportions of enzymes, bio surfactants, nutrients and other necessary constituents for complete life cycles and biodegradation that converts the waste into a natural food source for the enhanced native bacteria found in the environment. The end result of this process is CO2 and water.
OSEII is an environmentally safe cleanup method because it uses natures own bioremediation processes to effectively eliminate hazardous materials.
OSE II is listed on the US Environmental Protection Agency’s National Contingency Plan for Oil Spills (NCP).
OSE II is approved by Marine Emergency Mutual Aid Centre (MEMAC) as the first authorized Bioremediation product and listed in Regional Organization for the Protection of the Marine Environment (ROPME).
OSE II will reduce your cleanup costs and permanently eliminate the hazardous waste problem in place, with no secondary cleanup required.
OSE II is the world’s most environmentally safe and cost effective bioremediation process for the permanent removal of hazardous.
Shoreline Clean-Up and Response
When oil reaches the shoreline, considerable effort may be required to clean the affected areas. It is therefore essential that comprehensive and well-rehearsed arrangements for shoreline clean-up are included in contingency plans. The techniques available for shoreline clean-up are relatively straightforward and do not normally require specialised equipment. However, inappropriate techniques and poor organisation can aggravate the impacts caused by the oil itself.
The selection of the most appropriate clean-up techniques requires a rapid evaluation of the degree and type of contamination, together with the length, nature and accessibility of the affected coastline. Where possible, it is important to start removing oil from contaminated shorelines as quickly as practicably possible. As time passes and the oil weathers, it will stick more firmly to rocks and sea walls, and may become mixed or buried in sediments.
Shoreline clean-up operations are often considered in three stages; Stage 1 - bulk oil is removed from the shore to prevent remobilization; Stage 2 - removal of stranded oil and oiled shoreline material which is often the most protracted part of shoreline clean-up, and; Stage 3 - final clean-up of light contamination and removal of stains, if required. Depending upon the nature of the contamination, progression through each of these stages may not be required. Consideration will also need to be given to the environmental sensitivity of the shoreline so as to ensure the planned level of cleaning will not cause more harm than leaving the oil in place.
Experience from many incidents has shown that the most costly and time-consuming component of the overall oil spill response is the treatment or disposal of collected waste. As a result, the chosen clean-up strategy should aim to minimise the waste generated.
For many shoreline types and response scenarios, the removal of all traces of oil will be extremely difficult or inadvisable due to environmental or health and safety concerns. As a consequence, it is important that the criteria for deciding when a particular work site is sufficiently clean to allow work to terminate. The criteria for termination of the clean-up are usually discussed jointly and agreed following joint inspections by representatives of the various organizations involved in the response.
Flushing out oil buried in a sand beach using low pressure water supplied through lances and perforated pipes
There are a wide range of clean-up techniques available for affected shorelines but many of these may be more appropriate to just one stage of the response or one shoreline type.
During Stage 1 clean-up, the use of vacuum trucks, pumps and skimmers may be useful on pooled liquid bulk oil. For very viscous or emulsified bulk oil or oiled-soaked soft sediment, mechanical collection using a variety of non-specialized civil engineering or agricultural machinery could be used to collected and remove stranded oil and contaminated material. In many parts of the world, the use of manpower to collect oil and contaminated shoreline material is an important strategy and can be particularly useful on sensitive shores and areas inaccessible to vehicles.
Stage 2 clean-up might involve flushing, a technique that uses high volumes of low-pressure water to wash stranded or buried oil from shorelines. Similar in principle to flushing is surf washing, whereby the natural cleaning action of the shoreline waves are used to release the oil from within the shore sediment.
During the latter stages of a shoreline clean-up, other techniques may be deployed to complete the work. High pressure washing using either hot or cold water can be used on most hard surfaces, particularly on man-made structures within commercial and similar areas where natural cleaning is likely to be insufficient or too slow. Machinery can be employed to attain the required level of cleaning; pebbles and cobbles can be washed successfully in the revolving drums of concrete mixers or purpose built facilities and ploughs towed behind tractors and sand sieving/beach cleaning machines can both be used to clean high amenity use beaches to a high standard.
In situations where restricted access to rocky or cobble shorelines prevents the use of pressure washing or other equipment, wiping by hand may be the only option for the active removal of oil.
In certain circumstances, the use of bioremediation product (OSEII ) can be considered. Bioremediation is the term used to describe the range of processes, and related products, which can be used to accelerate the natural degradation of oil into simple compounds. Natural biodegradation can be usefully accelerated in areas where nutrients or microbes may be limited such as the clean-up of old industrial areas.
Shoreline type plays an important role in determining the most suitable clean-up techniques that might be most suitable for removing the oil. In considering the clean-up of a specific shoreline type, three factors are important to consider; the level of amenity use, the environmental sensitivity and the exposure of the shoreline to natural cleaning action.
Ports, harbors, sea defenses and similar man-made structures are usually in areas of high amenity use, are constructed from concrete or similar materials and have low environmental sensitivity. Clean-up techniques for this type of shoreline might utilize high pressure washing or flushing with the priority being a high level of oil removal. Natural hard surfaces, such as bedrock or boulders, can be cleaned using similar methods to man-made structures. However, the natural shore often has greater environmental sensitivity and exposure to wave action. Consequently, clean-up activities must take care to minimize impact on fauna and flora and the termination of active cleaning should consider the natural cleaning potential.
Cobble, pebble and shingle shores are one of the most difficult to clean satisfactorily as the oil can penetrate into the spaces between the stones and deep into the beach. Often the poor load-bearing structure of these shores means that mechanical collection is problematic. As a result, flushing and surf washing techniques, together with mechanical washing are typically the most useful clean-up techniques.
Sand beaches are often regarded as having high amenity value and a priority is given to cleaning them. Oil penetration into many beaches is limited and this makes them one of the easiest shorelines to clean. However, oil can become buried due to tidal or wave action. Mechanically-assisted manual clean-up, flushing and surf washing can all be useful on this shoreline type. Ploughing and sand sieving can produce a high level of cleaning where the beach has important amenity value. Care should be taken with all techniques to avoid removing clean sand from the beach which may cause erosion problems.
Muddy shores are amongst the hardest to clean as they are sensitive to physical damage by clean-up operations and often have high environmental sensitivity. In temperate climates, the marsh vegetation typical of these shores often survives a single oil smothering. In the tropics, the impact of oil on the mangrove vegetation is less predictable and dependent on species. Wherever possible, it is preferable to allow oil that arrives on this type of shoreline to whether naturally. Where the removal of oil is essential, flushing by OSEII is most likely the best options.