The Ship Escort Response Vessel System (SERVS) of Alyeska Pipeline Service Company (Alyeska) in Valdez Alaska is responsible for overseeing the prevention, preparedness, and response activities for the safe transportation of oil through Prince William Sound. Since the inception of SERVS in 1989, escort vessels have accompanied laden tankers through Prince William Sound from the Valdez Marine Terminal to the Gulf of Alaska, a distance of approximately 70 miles. The tankers pass through the pristine Prince William Sound, which encompasses over 2,500 square miles, with fjord-like topography and a subarctic climate. The evolution of the tanker escort system began with the emer-gency order issued by the state of Alaska in 1989 immediately after the grounding of the Exxon Valdez. A fleet of 12 vessels, each singular in purpose, was quickly developed: three dedi-cated pairs of escorts (comprised of an escort response vessel and tug), response barge standby vessels, and four dedicated docking tugs. The emphasis was more on oil spill response than prevention, and there was little interchangeability between vessels and their missions. In subsequent years, a variety of factors has caused changes to the escort system and vessel mix. These included the Disabled Tanker Towing Study, Prince William Sound Risk Assessment Promulgation of Federal Escort Requirements, oil spill response responsibility in the Gulf of Alaska, tanker vapor recovery, re-duction in pipeline throughput, and weather restrictions. Addi-tionally, industry instituted voluntary measures such as ice scouts and sentinel standby escorts for inbound tankers in ballast have affected the escort system, in addition to the experience gained in the operation the system. As the escort system matured, there was a marked emphasis and focus on oil spill prevention, fleet modernization, and multi-purpose vessels to increase capabilities while maximizing efficiencies. Alyeska/SERVS embarked on a dedicated strategy to upgrade the specialized vessel fleet of 12 vessels to a fleet composed of fewer multipurpose vessels. This strategy encom-passed a technological and operational enhancement of the fleet, significantly improving the prevention posture while maintaining the necessary response capabilities. Today, the Alyeska/SERVS escort fleet consists of nine multipurpose vessels. The cornerstones of the escort fleet are the two 10,192 horsepower Voith Schneider enhanced tractor tugs and the three 10,192 horsepower Z drive Prevention and Re-sponse Tugs, all specifically designed, constructed, and outfitted for tanker escorting. The combination of these vessels for tanker escorting utilizes complimentary best available technology to ensure the safe transit of tankers through Prince William Sound.
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