376 



(1) The LOT system cannot be applied to tankers in the oil prodiict trade since 

 refined products cannot be mixed with one another and cannot tolerate salt 

 content in the same way as most crude oils ; 



(2) Certain ballast voyages can be so short as to preclude the time necessary 

 for satisfactory operation of the LOT systems ; 



(3) Depending on sea conditions, the necessary separation process may not 

 be completely effective ; 



(4) The oil-water interface in the holding tank cannot be accurately de- 

 termined and this results in a portion of the lower layer of oil being drawn off 

 the water ; and 



(5) Some components of oil are water soluble. 



A total of 967,000 metric tons of oil per year influx to the marine environment 

 is attributed to tanker operations based on the following assumptions : 



(1) 75 percent of the 1,300 million metric tons of oil transported at sea (Sun 

 Oil Co., cited in Porricelli, Keith and Storch, 1971) is carried on tankers equipped 

 to operate with the LOT systems ; 



(2) The LOT system is 80 percent effective ; 



(3) The clingage is 0.4 percent of the total cargo capacity ; 



(4) Tanks are ballasted and cleaned to the percentages mentioned previously, 

 that is, one-fifth to one-third and one-third to two-fifths of the tanks, respec- 

 tively ; and 



(5) 15 percent of the clingage is taken out of the tanks upon Dumoine oily 

 ballast. 



Pollution From U.S. Flag Vessels 



Carrying approximately 5.5% of the total oil carried per year or 71 million 

 metric tons, approxmately 53,000 metric tons of oil can be attributed to op- 

 erational discharges from U.S. tankers. All U.S. vessels including ships other 

 than tankers contribute approximately 39,000 metric tons of oil due to dis- 

 charges of bilge water containing oil leaked from machinery spaces, leaks and 

 bunkering spills. Worldwide oil discharge figures were computed based on the 

 premise that all oil transported was crude. The actual figure of crude ship- 

 ment to total tonnage is about 90%, but this percentage was considered large 

 enough to warrant application of the LOT system criteria to all oil shipped, 

 even though LOT is generally not practiced by vessels carrying refined prod- 

 ucts. Applying the discharge limitation of 1/15,000 the total cargo carrying ca- 

 pacity of a tanker to the total oil carried by U.S. vessels (71 million metric tons), 

 the resulting quantity of oil allowed to be discharged is 4730 metric tons which 

 is less than one tenth the estimated 53,(XX) metric tons being discharged by U.S. 

 vessels under present legislation. In a worst case situation under present legis- 

 lation, all tank washings and dirty ballast would be allowed to be discharged 

 without limitation outside of prohibited zones, and at a rate no greater than 

 100 parts per million (ppm) inside of prohibited zones (for certain vessels, the 

 less than 100 ppm criteria would apply worldwide). It is even possible for a 

 vessel to discharge its entire cargo at the above rates, therefore, introducing 

 a possible 71 million metric tons of oil into the world's oceans. The last situa- 

 tion of course is an extreme case that will never happen, but it does point out 

 that present legislation only regulates discharge rates from tankers and then 

 only in certain situations, whereas the proposed amendments put a finite limit 

 on the amount of oil that can be discharged from tankers as well as improved 

 rate discharge limitations. The difference between the two is greater than ten- 

 fold, considering present utilization of the LOT procedure by U.S. vessels. Ad- 

 ditionally, as stated earlier, present legislation allows oily water discharges 

 within prohibited zones whereas the proposed amendments do away with pro- 

 hibited zones and prohibit any discharge of oil or oily mixture within 50 miles 

 of the nearest land. The revised definition of oily mixture under this bill is a 

 further limitation of the proposed amendment that also has the advantage that 

 it is similar to the definition of harmful discharge applied under domestic 

 regulations. 



Under the 1961 Act. it is possible for oil record books to be falsified. Tlie pro- 

 posed amendments to the Act should helj) cure this problem, as oil record book 

 entries will be tied to the ship's log. The more expanded oil record book will 

 account for all oil received and discharged. CJreater specificity of information 

 entered and tank-by-tank information requirements will greatly facilitate efforts 

 in detecting violations of the Act. 



