How to Contain an Oil Spill
At present there is a large oil release in the Gulf of Mexico. It is not the first of its kind. Obviously one must try to confine it and then clean it up but what it is the right and effective way? What is a waste of time and resources and what works?
Ixtoc I was an exploratory oil well being drilled in the Bay of Campeche of the Gulf of Mexico, about 62 northwest of Ciudad del Carmen, Campeche in waters 160 feet deep. On 3 June 1979, the well suffered a blowout resulting in the third largest oil spill and the second largest accidental spill in history. What was effective then?
Under pressure from the Louisiana Governor and other state and local officials, the U.S. Army Corps of Engineers issued an emergency permit on May 27 authorizing the state of Louisiana to construct 45 miles of artificial berm — 300 feet wide at its base and rising six feet out of the gulf — in an attempt to protect delta wetlands and barrier islands from the encroaching oil. How effective will this be?
Not counting the present Gulf of Mexico release, the 3 largest oil releases in history are:
Gulf War January 1991 1.5 million tons
US Lakeview Gusher March 1909 1.2 million tons
Ixtoc June 1979 to March 1980 0.5 million tons
In the initial stages of the Ixtoc spill, an estimated 30,000 barrels of oil per day were flowing from the well. In July 1979, the pumping of mud into the well reduced the flow to 20,000 barrels per day, and early in August the pumping of nearly 100,000 steel, iron, and lead balls into the well reduced the flow to 10,000 barrels per day. Pemex claimed that half of the released oil burned when it reached the surface, a third of it evaporated, and the rest was contained or dispersed. Mexican authorities also drilled two relief wells into the main well to lower the pressure of the blowout, however the oil continued to flow for three months following the completion of the first relief well. Booms were also utilized across key water inlets in the area.
In the Ixtoc case the real solution was drilling relief wells to take the pressure off the release point. Even then it took time to end the release.
All solutions carry some risk with them. The typical oil release control measures are:
Booms - Good at containment but limited if the release is large.
Skimming - Effective but requires low winds
Control Burns - Cause smoke and air pollution but does remove the oil. Again low winds and a controlled area is required.
Dispersants - May be toxic unto themselves and spreads the oil more widely but aids in its ultimate degradation.
Accelerated bio-remediation - Most effective on smaller releases but may cause long term environmental effects.
Now let us consider the present situation in the Gulf of Mexico. After some abortive capping attempts, the recent siphoning actions does show some reduction in oil release flow. A true relief well is also planned but may not be constructed until August. This is equivalent to the Ixtoc situation and the side wells that were installed.
As stated earlier Louisiana and others are planning to add large berms to prevent the oil from reaching wetlands. The problem with berms is that they tend to get washed away especially in hurricanes and take time to construct. How effective they will be is debatable but they would provide a form of containment similar to an oil boom.
The Louisiana berm will not be continuous resulting in a strong likelihood that oil will flow in through the gaps before then possibly become trapped in wetlands.
In addition to its debatable prospects for success, the Louisiana berm project would be very expensive. The application from the state of Louisiana estimated the cost to be about $3.8 million per mile, or about $171 million for the initial 45 miles of the permitted project. In its comments on the state’s application, the U.S. Department of Interior notes that cost estimates for mobilizing sand in the area have already been produced for the planning of future barrier island restoration. Using these numbers, the Interior Department suggests the costs are likely to be closer to $500 million. Thad Allen, the U.S. Coast Guard admiral in charge of the spill cleanup, said Wednesday that BP has agreed to pay for construction of the 45 mile line of sand berms, which he estimated would cost $360 million.
The prospects for the future is that the present oil release will continue for several months before it finally ends. Berms, such as are being discussed, will provide a temporary solution but such berms will be transient and will not last long.
For further information: http://e360.yale.edu/content/feature.msp?id=2282&utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+YaleEnvironment360+%28Yale+Environment+360%29&utm_content=Google+Reader or http://en.wikipedia.org/wiki/Oil_spill