There are two major steps involved in the successful oil spill cleanup. They are containment and recovery. The following outlines the techniques and equipment that are used to conduct oil spill cleanup efforts.
When an oil spill occurs on the water, it is critical to contain the spill as quickly as possible in order to minimize danger and potential damage to persons, property, and natural resources. Containment equipment is used to restrict the spread of oil and allow for its recovery, removal, or dispersal. The most common type of equipment used to control the spread of oil is floating barriers, called booms.
Oil Spill Cleanup Booms
Containment booms are used to control the spread of oil to reduce the possibility of polluting shorelines and other resources, as well as to concentrate oil in thicker surface layers, making oil spill cleanup easier. In addition booms may be used to divert and channel oil slicks along desired paths, making them easier to remove from the surface of the water.
An above-water freeboard to contain the oil and to help prevent waves from splashing over the top of the boom.Although there is a great deal of variation in the design and construction of booms, all generally share four basic characteristics:
- A floatation device
- A below-water skirt to contain the oil and help reduce the amount of oil lost under the boom.
- A longitudinal support usually a chain or cable running along the bottom of the skirt, that strengthens the boom against wind and wave action; may also serve as a weight or ballast to add stability and help keep the boom upright.
Oil Spill Cleanup
SpillMaster Booms for oil cleanup can be divided into several basic types. Fence booms have a high freeboard and a flat flotation device making them the least effective in rough water, where wave and wind action can cause the boom to twist, but they are well suited for roller reel systems. Non-rigid inflatable booms come in many shapes. They perform well in rough seas. However, they tend to be more expensive, more complicated to use, and puncture and deflate easily. Permanent booms perform well at shore side facilities. They are tough and can stay in the water year-round. Because they stay in the water, they often save much needed time during the early stages of an oil spill cleanup. All boom types are greatly affected by the conditions at sea; the higher the waves swell, the less effective the booms become to facilitate oil spill cleanup.
Booms can be fixed to a structure, such as a pier or buoy or towed behind or alongside one or more vessels. When anchored or moored, the boom is anchored below the water surface.
It is necessary for stationary booms to be monitored or tended due to changes produced by shifting tides, tidal currents, winds, or other factors that influence water depth, direction and force of motion. People must tend the booms around the clock to monitor and adjust the equipment unless the boom is permanently installed at a pier where the installation is propositioned and self-adjusting.
The forces exerted by currents, waves, and wind may impair the ability of a boom to hold oil. Loss of oil occurring when friction between the oil and water causes droplets of oil to separate from a slick and be pulled under the boom is called entrainment. Currents or tow speeds greater than three-quarters of a knot may cause entrainment. Wind and waves can force oil over the top of a boom’s freeboard or even flatten the boom into the water, causing it to release the contained oil. Mechanical problems and improper mooring can also cause a boom to fail.
While most booms perform well in gentle seas with smooth, long waves, rough and choppy water is likely to contribute to boom failure. In some circumstances, lengthening a boom skirt or freeboard can help to contain the oil. Because they have more resistance to natural forces such as wind, waves, and currents, oversized booms are hard to work with and more prone to failure or leakage than smaller ones. Generally, booms will not operate properly when waves are higher than one meter or currents are moving faster than one knot per hour. However careful placement of booms in river and bay environments can deflect the oil to areas of lower current and shallower water for recovery.