Almost all these spills will be quite small. The mean of these 

 spills is about 100 gallons, and it is quite likely that an 

 individual spill will be less than the mean. 



8. With respect to total volume spilled over the field life, the 

 mean for the small find is about 900,000 gallons for the small 

 find landed by pipeline and 1,100,000 gallons for the small find 

 landed by tanker. The variance is quite large and there is a 

 substantial probability in both cases there will be no large spills 

 at all. The standard deviation for the small find landed by 

 pipeline is over 2.65 million gallons; if landed by tanker, 2.45 

 million gallons. Thus, there is a slightly higher chance of both 

 small total spillage and wery large total spillage with the pipe- 

 line rather than the tanker, reflecting our greater uncertainty 

 about pipelines. 



For a large find, the mean of the total spillage is 15 million 

 gallons for pipeline transport and 19 million gallons for 

 tanker. The ratio of the standard deviation to the mean is not 

 quite so large for the large find as the small find, as the law 

 of large numbers is beginning to work, although weakly. The stan- 

 dard deviation of the total spillage assuming tanker transport 

 for the large find is 10.3 million gallons, and for the pipeline 

 option is 11.5 million gallons. 



9. All the above estimates of probabilities can reasonably be 

 regarded as moderately pessimistic. They assume no improvement 

 in technology or operations over the recent past. 



10. Finally, it is extremely important to realize that the above 

 estimates of probabilities do not represent the net effect of 

 0CS development. The net effect will depend on what one assumes 

 about the oil which would be landed in the absence of the devel- 

 opment. For example, if one assumes the same amount of crude 

 will be landed on the East Coast with or without a development, 

 then according to the analysis there is a substantial probability 

 that there will be as many large spills without the find as with 

 the find. 



5.2 COASTAL ECOSYSTEM IMPACTS 



Coastal ecosystems which may be affected by 0CS activities include: 



a. the offshore, oceanic region; 



b. the nearshore zone; 



c. major estuaries and bays; 



d. salt marshes and wetlands. 



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