auxiliary power systems to propel the vessel if the primary system fails. 

 Holding oily bilge and ballast water and tank washings for discharge to 

 oil/water separation facilities ashore before reloading could obviate the 

 need for many of the above design features. 



4.19.3 Transfer Systems 



In the transportation system small-volume spillage occurs routinely, 

 particularly at transfer points between different components of the 

 system (e.g., terminal-tanker, refinery-pipeline). Moreover, accidents, 

 human errors, and equipment failures can cause large spills at any time. 

 Spills are difficult to control and can often cause extensive environ- 

 mental disruption if they reach beaches or marshes. Terminal location and 

 design should be such as to minimize the possibilities of a spill. The 

 less often crude oil is transferred, the less likely it is to spill. For 

 instance, a transfer operation involving pumping from tankers to offshore 

 tanks, to lighters or to refineries, requires three handlings, whereas 

 pumping from tankers to pipelines to refineries involves only two 

 [172]. 



Oil and gas transfer equipment should constantly be monitored in 

 order to avoid spillage. Flexible hoses on an offshore transfer buoy, 

 or single point mooring (SPM), may deteriorate rapidly when storm waters 

 beat them against or wrap them around an SPM. Fixed couplings may break, 

 particularly when a ship drifts. Pumps may fail and pipelines rupture. 

 LNG transfer equipment is subject to the additional problems of handling 

 a liquid at 260 degrees (F) below zero. This thermal stress can only be 

 overcome by special materials which do not become brittle at low 

 temperatures. 



Human errors, such as overfilling and system mismanagement, can be 

 minimized by the use of properly trained personnel in transferring oil and 

 gas, and by systems designed to reduce the potential for error and to 

 monitor human actions. 



The breakdown of the ways oil spills can occur as a result of terminal 

 and tanker operations and tanker accidents is shown in Figure 52. 



4.19.4 Oil Spill Fate and Containment 



Crude oil is a combination of numerous hydrocarbons. Processed oil 

 can include any of the types of oil present in the original crude oil or 

 new petroleum compounds derived from these substances. The types of 

 hydrocarbons spilled will determine, to a large extent, the impact on 

 organisms in the receiving waters. For example, lighter hydrocarbons, 

 such as gasoline and kerosene, will evaporate more quickly than heavier 

 hydrocarbons. Oil with high percentages of aromatic hydrocarbons dissolve 

 in water most easily and are likely to have more serious impacts than oils 

 with lower concentrations of aromatics [7]. 



193 



