Disturbance factors should be recognized as an important considera- 

 tion because they extend the effects of the project beyond the 

 boundaries of the immediate site. 



4. Key attribute alterations 



The key attribute alterations include direct removal of vegetation 

 and consumers and introduction of pollutants. Since the area 

 affected by construction is small (relative to an expansive marsh), 

 the loss of food and cover for supported consumers is insignificant. 

 The extent of impacts from pollutants is not predictable. 



Because the persistence and potency of spilled components is highly 

 variable, the extent of impacts from pollutants is not predictable. 

 Since the effects of sublethal levels of persistent pollutants are 

 not catastrophic (as is the case in a blowout or major spill), the 

 toxins may permeate large numbers of individuals and species before 

 damage is noticed. By this time, affected organisms and waterflows 

 will have served as agents of dispersal, with the result that areas 

 much larger than the wellsite may be affected. 



Spills and cleanup. 

 1. Activity sequence 



Spills and leaks are the result of equipment failure, improper oper- 

 ation of equipment, or human error. In spite of automatic devices 

 to control and shut down some equipment during failure, leaks and 

 spills do occur. Although many kinds of materials may be spilled 

 during oil and gas operations, most of the specific discussion in 

 this section assumes the spillage of crude oil. When spills do 

 occur, first efforts should be directed towards containment/ 

 confinement of the petroleum. That the source of the problem should 

 be discovered and repaired is obvious. The equipment and methodol- 

 ogy utilized is dependent upon the size of the spill, the kind of 

 material spilled, the biotic and abiotic characteristics of the 

 affected and adjacent area, and other site-specific -features. 



The presence of a large amount of water on the surface of the salt 

 marsh ecosystem is a confounding factor in spills and cleanup. 

 Buoyant petroleum materials spread rapidly into thin films, and the 

 movement of the underlying water may further dissipate the spill. 

 Booms, dikes, dams, straw, and other physical means are frequently 

 used to contain the petroleum. Boats, trucks, barges, helicopters, 

 and marsh buggies may be necessary for placement of these barriers. 

 Once containment has been accomplished, piston film herders or 

 physical means may be used to concentrate the oil. Skimmers or 



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