Technical

Oil Spills

An oil spill is the release of a liquid petroleum hydrocarbon into the environment, especially marine areas, due to human activity, and is a form of pollution. The term is usually applied to marine oil spills, where oil is released into the ocean, but spills may also occur on land.

Oil spills may be due to releases of crude oil from tankers, offshore platforms, drilling rigs and wells, as well as spills of refined petroleum products (gasoline, diesel) and their by-products, heavier fuels used by large ships such as bunker fuel, or the spill of any oily refuse or waste oil. Even with sophisticated safety measures in place, the risk of oil spill remains. Despite every endeavor to prevent them, oil spills can still happen. This underlines the need to address the risk and have appropriate response capability in the event of an incident.

Oil spills often result in both immediate and long-term environmental damage. Some of the environmental damage caused by an oil spill can last for decades after the spill occurs. The biological damage caused by an oil spill will be governed by a combination of several factors including: (1) the type of oil spilled, (2) the dose of oil, (3) the physiographic of the area of the spill, (4) weather conditions at the time of the spill, (5) the biota of the area, (6) the season of the spill, (7) previous exposure of the area to oil, (8) exposure to other previous exposure of the area to oil, (8) exposure to other pollutants, and (9) the treatment of the spill.

Oil spill control and cleanup

There are different methodologies that can be adopted for the purpose of cleaning up oil spills.

Oil Booms

Oil booms are a very popular method of controlling oil spills. There are various kinds of oil booms that have been designed for various areas where the oil spillage might occur, leading to a quite thorough oil spill cleanup.

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 recovery 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.

Although there is a great deal of variation in the design and construction of booms, all generally share four basic characteristics:

  • An above-water “freeboard” to contain the oil and to help prevent waves from splashing oil over the top of the boom
  • A flotation 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.

Booms can be divided into several basic types. Fence booms have a high freeboard and a flat flotation device, making them least effective in rough water, where wave and wind action can cause the boom to twist. Round or “curtain” booms have a more circular flotation device and a continuous skirt. They perform well in rough water, but are more difficult to clean and store than fence booms. Non-rigid inflatable booms come in many shapes. They are easy to clean and store, and they perform well in rough seas. However, they tend to be expensive, more complicated to use, and puncture and deflate easily. All boom types are greatly affected by the conditions at sea; the higher the waves swell, the less effective booms become.

Booms can be fixed to a structure, such as a pier or a buoy, or towed behind or alongside one or more vessels. When stationary 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 and direction and force of motion. People must tend booms around the clock to monitor and adjust the equipment.

Generally, booms will not operate properly when waves are higher than one meter or currents are moving faster than one knot per hour. However, new technologies, such as submergence plane booms and entrainment inhibitors, are being developed that will allow booms to operate at higher speeds while retaining more oil.

Sorbents

Sorbents are materials that are placed on the surface of the spillage affected area to suck and absorb the oil from the surface of the water leading to an oil spill cleanup.
Materials that are capable of absorbing many times their weight in oil can be used to wipe up oil from contaminated shorelines. These materials are often designed as large squares, much like paper towels, or shaped into “mops.” The squares or mops are used to wipe the shoreline or oily rocks during which time the absorbents are filled with as much oil as they can hold.

There are advantages to the use of absorbents. They can be used to clean up any kind of oil on any shoreline that can be reached by response personnel. The use of absorbents is generally not harmful to the shoreline itself or to the organisms that live on it, and no material is left behind following the cleanup effort. Some sorbents are reusable, reducing the need for disposal after a spill.

Wiping with absorbent materials requires the use of a large quantity of material and several personnel. Personnel must wear proper protective clothing to minimize direct contact with the oil as they are removing it. Oil-filled absorbents and protective clothing that are used by response personnel must be properly disposed of following cleanup, which can be costly. In addition, the intrusion of many people onto an isolated shoreline may disrupt animal behaviors such as breeding or nesting.

The following characteristics must be considered when choosing sorbents for cleaning up spills:

  • Rate of absorption—the rate of absorption varies with the thickness of the oil. Light oils are soaked up more quickly than heavy ones.
  • Oil retention—the weight of recovered oil can cause a sorbent structure to sag and deform. When it is lifted out of the water, it can release oil that is trapped in its pores. During recovery of absorbent materials, lighter, less viscous oil is lost through the pores more easily than heavier, more viscous oil.
  • Ease of application—Sorbents may be applied to spills manually or mechanically, using blowers or fans. Many natural organic sorbents that exist as loose materials, such as clay and vermiculite, are dusty, difficult to apply in windy conditions, and potentially hazardous if inhaled.

Natural inorganic sorbents include clay, perlite, vermiculite, glass, wool, sand, and volcanic ash. They can absorb from 4 to 20 times their weight in oil. Inorganic substances, like organic substances, are inexpensive and readily available in large quantities. Synthetic sorbents include man-made materials that are similar to plastics, such as polyurethane, polyethylene, and nylon fibers. Most synthetic sorbents can absorb as much as 70 times their weight in oil, and some types can be cleaned and reused several times. Synthetic sorbents that cannot be cleaned after they are used can present difficulties because they must be stored temporarily until they can be disposed of properly.

Oil spill kits

The best hands-on way to tackle an oil spill problem is to use an oil spill kit. An oil spill kit comes with the necessary items to counteract and stop the spilled oil from creating a larger undesirable effect on the floors and in case of waters, spreading to a wider range.

An oil spill kit comes in various sizes which are designed keeping in mind the reach of the spilled oil and the quantity that will be required to solve the oil spill problem. Devising such a method is good thinking because when it comes to an oil spill problem, no one can actually be sure about the exact quantity of remedial measures to be used. The least amount of an oil spill kit that is available in the market is about seven liters while the maximum capacity one is of about 476 liters.

An oil spill kit typically contains the following items – absorbent mats/pads, dust-pans, protective overalls, waste- bags, oil splash goggles, gloves and vinyl or rubber shoe covers to protect the user from the harmful effects of the spilled material, which could even include acids and other toxic substances which could be present in the spilled area.

Regulations for spill prevention

  • Double hulls: The law states that all ships transporting hulls must have double hulls before 2015. Double hulls reduce the possibility of oil spills during transport by 60% has compared to single hull ships.
  • Spill funds: This law specifies that Oil companies pay certain amounts to the government so that in case of a spill, the government can pay for a clean up.
  • Navigation: The law states that the Coast Guard must know where oil tankers can navigate through without a spill occurring and enforcing it.

Chemical spills

A chemical spill is a situation in which a chemical is accidentally released. In the case of non-toxic chemicals, dealing with a spill is usually very straightforward, since the spill simply needs to be cleaned up. However, spills of toxic chemicals represent a more serious problem, especially in the case of spills of multiple chemicals which could react with each other. Many nations have specific laws concerning large-scale chemical spills such as the release of chemicals from a damaged chemical tanker.

There are a number of things which can cause a chemical spill. In a laboratory, a dropped beaker, piece of malfunctioning equipment, or poorly handled package of chemicals can potentially cause a spill. On a larger scale, chemicals can be spilled in train and auto accidents involving chemical tankers, or they can be released by seagoing ships or aircraft. Chemical plants can also cause spills with imperfect safety procedures, accidents, or deliberate dumping of chemicals. Most governments treat large scale spills as the responsibility of the person who caused them, rather than the manufacturer of the chemical.