Compared with refined fuel spills, which dissipate or evaporate quickly, thick and sticky crude oil spills can require a long, arduous cleanup, reports the International Tank Owners Pollution Federation. Difficult to break apart, heavy fuels not only emulsify into stubborn mats, but also travel vast distances from the spill site. In addition, larger spills (for example, 10,000 tons versus 100 tons) translate into a wider contamination zones.
Because oil and water do not mix, a spill will spread across water as well as change in form. The spread may also veer in chaotic directions because of waves, winds, currents and tides. If the response to a spill is not speedy, the spill may widen out to an area that is impossible to contain. Although a portion of the oil will evaporate, some oil may turn into hydrocarbon-releasing tar balls and sink to the bottom of the water, where it stays for a lengthy period. Still other oil will be whipped into “mousse” or a frothy emulsion, according to the International Tank Owners Pollution Federation.
Moving outside shipping lanes to avoid ice, the tanker Exxon Valdez beached on a reef in the Prince William Sound, Alaska, in March 1989. Almost 11 million gallons of crude oil were spilled within a half-dozen hours and contaminated 1,100 miles of Alaskan coastline. Initially, the spill concentrated in an area close to Bligh Island. Days later, a storm with 70 mph winds turned the oil into tar balls and mousse and dispersed the spill over a vast area. The response involved more than 85 aircraft, 1,400 ships and 11,000 people, reports the Encyclopedia of Earth.
Different types of spill sites can present varying degrees of difficulty in cleanup. In the case of the Exxon Valdez, the oil seeped below the surface of rocky shores laden with coarse sand also covered rock faces that were challenging to reach, reports the Encyclopedia of Earth. Once oil lands on a coastline, the spill can easily turn into a disaster. At every high tide, the shoreline oil floats off and migrates to another location, thus complicating the tracking of the spill. The use of microorganisms to accelerate the degradation of oil, known as bioremediation, can help remove oil buried in soils and rocks.
Depending on spill size, the cleanup equipment—such as booms, skimmers and dispersants—and response teams may not be enough to protect the environment. According to the Encyclopedia of Earth, even though 100 miles of boom was used to contain the Exxon Valdez spill, unseasoned workers were brought in to manage the equipment. They botched the deployment of the boom, resulting in leakage.