New vessels arrive
First two new tugs and one of the spill response barges are now in Valdez
Alan Bailey Petroleum News
The first three vessels that will form part of Edison Chouest Offshore’s new fleet supporting the Valdez Marine Terminal have arrived in Valdez and are undergoing sea trials and demonstrations, in preparation for the transition of the terminal marine services from Crowley Marine Corp. The transition results from a decision by Alyeska Pipeline Service Co., operator of the trans-Alaska pipeline and the marine terminal, to put the contract for the marine services to competitive bid - in August 2016 Alyeska announced that it was awarding the contract to Edison Chouest.
The switchover is officially scheduled for July 1. But new Edison Chouest vessels are arriving during the months leading up to the handover and, as they gain regulatory approval, will progressively move into the terminal’s marine operations, Mike Day, SERVS manager of the marine transition, said during a media tour of the three newly arrived vessels.
Two tugs and response barge The vessels that are now in Valdez consist of the Commander, a large, very powerful tug designed for escorting oil tankers to and from the terminal; the Elrington, a smaller general purpose tug; and the OSRB-1, a 400-foot oil spill response barge. Edison Chouest has built these vessels specifically for the Valdez terminal marine services. In total the company is building five new tugs, purpose designed for escorting tankers; four smaller general purpose tugs; and four new barges, purpose built for oil spill response. The company is also going to bring one of its existing general purpose tugs to Valdez and is taking over an existing response barge, equipped to support nearshore spill response operations. Another existing barge is being converted for lightering use.
Day said that two more of the new tugs are on their way and should arrive in about a couple of weeks time. All of the vessels are expected to arrive by the middle of June - everything is on schedule, he said.
The marine services Alyeska’s Ship Escort/Response Vessel System, known as SERVS, manages the marine services, which provide tug assistance for tankers berthing at the Valdez Marine Terminal, while supporting oil spill prevention and contingency plans for the terminal and the tanker operations. The marine services form a vital component of the transportation arrangements for shipping crude oil from Alaska.
Powerful escort tugs are tethered to the sterns of laden tankers departing the Valdez terminal and crossing the more nearshore area of the neighboring Prince William Sound. In the event of a problem a tug can stop a tanker from moving or otherwise assist the vessel. And two tugs always escort tankers across Prince William Sound.
Andres Morales, SERVS director, explained that a powerful tug also stands sentinel at the Hinchinbrook Entrance to Prince William Sound until a tanker is safely 17 miles out into the Gulf of Alaska. And SERVS stages some tugs, response barges and spill response equipment throughout Prince William Sound, as a precaution against the possibility of a tanker running into difficulties. Equipment staged includes a lightering barge, for offloading oil from a tanker, if necessary. SERVS also has more than 400 local fishing vessels under contract, as vessels of opportunity to assist with oil skimming activities, should need arise. And response arrangements must be capable of recovering up to 300,000 barrels of oil in the first 72 hours of a response, Morales said.
Exercises and training To date the new Commander escort tug has participated in 28 tanker tether exercises, all of which were completed successfully, Day said. Six of the 10 escort tug captains have been involved in these exercises. Two tanker towing exercises have also been successfully completed. The Elrington general purpose tug has conducted four barge deployment exercises, towing the response barge, he said.
Day emphasized that the Edison Chouest crew members are very experienced mariners, with extensive towing experience. However, since July of last year SERVS has been conducting crew training and education specific to spill prevention and response activities in the Prince William Sound area, and to the characteristics and history of the region. Training includes the specific procedures involved in escorting tankers using the marine terminal. An Edison Chouest tug bridge simulator allows crews to practice various tug operations.
Moreover, every Edison Chouest captain has now spent at least a week in Valdez on board a Crowley escort tug, experiencing tanker escort operations in rough winter weather, Day said.
SUBHED: Custom designs
The new escort tugs have been specifically designed for SERVS. They have twin engines with a total power of 12,300 horsepower, together with an azimuthal drive system that can swivel around 360 degrees, hence enabling a high maneuverability along with high power output. The tug design involves a skeg, a form of keel, at the front, that can provide a resistive force if the tug is turned away from the direction of travel of the tanker that the tug is hitched to, Morales said.
The new tugs are more powerful than the existing tugs and are maneuverable over a wider range of speeds. Day also commented that the new escort tugs have winch systems at both bow and stern, thus enabling the tugs to perform towing duties as well as acting as tanker escorts. The winches are of a constant tension design and can be adjusted to the required tension level.
Response barge The new oil spill response barge, specifically designed for the Valdez and Prince William Sound arena, has a long, flat deck, with boom reels at one end, to enable twin lengths of oil containment boom to be inflated on deck, before being slid out into the water. A fishing vessel attaches to the far end of the boom and pulls the boom through the water alongside the barge, to bend the boom into a V shape, with the open end towards the barge’s direction of travel. One of the twin lengths of boom can go alongside each side of the barge. Then as a tug tows the barge though an oil slick, oil will be encapsulated by the boom. The boom is of a type that will continue to trap the oil, without spillage, while the barge is in motion, Day said.
Cranes on either side of the barge will lower an oil skimmer into the apex of each boom V, to remove oil from the water and transfer it into tanks inside the barge. Oil can subsequently be offloaded through a pipe system towards the rear of the barge.
More efficient skimmers The Crucial Inc. skimmers on the new barges use rotating disks of oil attracting material and are much more efficient than the old skimmers on the existing barges, Day said. The result will be a higher proportion of oil relative to water transferred from the skimmers into barge tanks, and hence a higher level of recovered oil storage efficiency. Moreover, the new barges have systems that, subject to appropriate permitting, allow water to be decanted from under the oil in the tanks and discharged back in front of the boom at the sides of the vessel.
Each barge will have a radar system and infrared cameras that can detect oil on water, to help steer the barge through an oil slick. And the barge command module is perched high above one end of the deck, for maximum visibility.
The barges also have systems for running salt water across their massive decks, to clear any buildup of snow in winter weather. And the vessels have been designed to have decks almost clear of equipment and piping, with most equipment fitted internally in the hull, an arrangement that maximizes personnel safety. The barges and tugs have standardized designs, for maximum efficiency.
By comparison, the existing barges are converted transportation barges, as much as 40 years old, with much equipment fitted on the decks and little standardization between the vessels.
Given that some escort tugs and barges will need to be stationed at remote locations for extended periods of time, the new vessels have comfortable crew quarters, with fully equipped galleys and refrigerated food storage.
Day emphasized that the takeover of the marine services by Edison Chouest is not a reflection of the service that Crowley has been providing. Crowley has been conducting excellent, professional operations for many years, he said.
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