BARRIERS 



The term "barrier" is defined by the American Heritage Dictionary as: 

 "A fence, wall or other structure built to bar passage. . .Anything material 

 or immaterial that acts to obstruct or prevent passage." In terms of oil 

 pollution response, "barriers" satisfy this definition exactly: i.e., the 

 physical placement of some obstruction to retard or stop the flow of spreading 

 oil, and thereby effect containment. 



As discussed by previous speakers, many different situations are encountered 

 in oil pollution response activities; thus, different types of containment 

 action are required. The following paragraphs briefly describe the different 

 types of barriers that can be used. These fall, generally, into two classes: 

 booms and earthen dams. 



BOOMS 



Oil containment booms are undoubtedly the most commonly recognized type 

 of barrier. The term "boom" in the oil pollution industry automatically 

 brings to mind a floatable collar encircling a slick. The following discussion 

 explains why this device is an effective tool in the stockpile of containment 

 equipment available to response personnel. Booms must have five components 

 if they are to be effective: 



1. Each boom must have a flotation member, which is necessary to 

 keep the boom afloat until the barrier is established. 



2. Each barrier must have a freeboard; that is, a portion of 

 the boom must be above the surface of the water to contain 

 the oil and prevent splashover. 



3. A corresponding component or skirt should be below the 

 surface of the water to provide a subsurface restraint for 

 collected oil. 



4. In order to keep the skirt in a vertical position to insure 

 effective containment, some form of ballast or weight must be 

 placed on or in the bottom of the skirt. 



5. An all-important longitudinal strength member must also be 

 present. This component, which is sometimes referred to as the 

 tension member, is designed to hold the boom together and to provide 

 the strength for towing and anchoring. It is usually placed between 

 the flotation and the bottom of the skirt. 



Two views of a typical boom with major components are illustrated in 

 Figure 1. 



In addition to the basic components, there are two additional characteristics 

 that should be mentioned since both affect efficiency. 



1. Stability : The ability of a boom to contain oil effectively is 

 normally dependent on its ability to remain fairly stable in wind, 

 waves, and surface and subsurface currents. 



2. Construction Materials : Materials used in the manufacture of booms 

 should be of a highly durable quality to minimize wear due to 

 abrasion and exposure to sunlight for extended periods. 



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