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Tanker Escort System

 

Human error, severe weather, complex geography, mechanical failure: Any of these can contribute to the disablement of a laden oil tanker in Prince William Sound. A disabled tanker requires immediate action. Tanker escorts can provide that, and much more.

What is the Escort System?

Lessons learned from the Exxon Valdez oil spill of 1989 led to the Oil Pollution Act of 1990 (OPA 90), which mandates that laden single-hull tankers be escorted by at least two towing vessels as the tankers travel through Prince William Sound. The purpose of this system is to have capable escorts in place to monitor conditions and alert the tanker of potential problems before they occur and help the tanker avoid any potential problems, as well as to assist a disabled tanker as quickly as possible or to begin a response in the event of a spill to water.

Prince William Sound’s world-class tanker escort system consists of two high-powered tugs accompanying each laden tanker through the sound. Several tugs are available under Alyeska Pipeline Service Company’s Ship Escort Response Vessel System (SERVS). (See our fact sheet on SERVS tugs.) The cost of SERVS is included in the operating costs that are factored into the present Trans Alaska Pipeline System (TAPS) tariff.

Escort vessels have these important functions:
• to watch for and report any sign of problems with a tanker
• to assist if a tanker encounters trouble
• to provide the first response should a spill occur

At least one of the two escorts is equipped with containment boom, oil skimmers, a work boat to deploy boom, recovered oil storage capacity and a trained response crew.

Left: The Aware, one of the system's newest prevention/ response tugs (PRTs), is designed specifically for escorting tankers and responding to incidents in Prince William Sound. (photo by Susan Sommer, PWSRCAC). Right: A tug escorts a tanker in Port Valdez.

Immediately following the Exxon Valdez oil spill, the governor ordered all tankers in Prince William Sound to be accompanied by two escorts. In 1994, the U.S. Coast Guard issued a final rule requiring two escorts for single-hull vessels as called for in OPA 90. Now, a system of close escorts and vessels on station covers the tanker route from the berths at Valdez to 17 miles seaward into the Gulf of Alaska. In Valdez Narrows, one of the escorts must actually be tethered to the tanker’s stern.

At the north end of the sound (from the Valdez Marine Terminal to Bligh Reef) and at the south end, where tankers enter the Gulf of Alaska via Hinchinbrook Entrance, all escorts must stay within a quarter nautical mile of the tanker. However, in the central part of the sound (from Bligh Reef to Hinchinbrook Entrance) there is more sea room and only one of the escorts is required to stay within a quarter nautical mile of the tanker. The other escort (called a “Sentinel”) may be stationed a few miles away at one of three points along the route, to enable quick response. Two close escorts are required through Hinchinbrook Entrance. After a tanker leaves Prince William Sound, a rescue tug must stay on station near Hinchinbrook Entrance until the tanker is at least 17 miles out to sea. See an illustration of escort zones. (pdf/780KB)

Within the sound, tankers are subject to various speed limits. The highest speed limit applies in central Prince William Sound. The lowest applies in Valdez Narrows. Laden tankers may not exceed a speed beyond which the escort vessels can reasonably be expected to safely bring the tanker under control.

Laden tanker speed limits in Prince William Sound:
Port Valdez: 10 knots
Valdez Narrows: 6 knots
Valdez Arm: 10 knots
Buoy #9: 8 knots
Under Ice Escort: safe speed
Central Sound: 12 knots
Hinchinbrook Entrance: 10 knots

Why Is the Escort System So Important?

The current escort system in the sound safeguards against oil spills caused by navigational errors, extreme weather, and human or organizational errors. It is the best method of preventing spills, which, despite technological improvements and training, are still extremely difficult to clean up.

Besides performing the traditional workload of a tugboat, the escorts also carry spill response equipment, have firefighting capabilities and can assist tankers navigate inclement weather, icebergs and varied geography.

Read an article about how important the current tanker escort system is, by PWSRCAC Executive Director John S. Devens. Published in the May 2005 issue of Alaska Business Monthly. (pdf/357KB)

Is the Escort System Permanent?

During 2005, discussions occurred concerning reducing the required number of vessels necessary to escort a laden tanker through Prince William Sound.

Federal statutes and regulations that require the tanker escort system specify that escort tugs are required for single-hull, laden tankers only. The regulations requiring two escorts will effectively sunset with the transition to a double-hull fleet, which is required by federal law to occur by 2015. Industry estimates the TAPS-tanker fleet will be comprised of double-hulls by as early as 2007. The State of Alaska Contingency Plans also require two escorts. Those plans are up for renewal in the fall of 2007, and this requirement could easily be removed.

Maintaining a strong and reliable escort fleet and preserving the practice of requiring two escorts for laden tanker transits is essential to the safe transportation of oil in the sound. The only way to ensure the continued operation of the Prince William Sound escort system is through a legal or regulatory imperative.

In 2006, the council sent a letter regarding changes to the Prince William Sound tug fleet to the U.S. Coast Guard, ADEC, and shippers. (pdf/122KB)

December 15, 2005, Prince William Sound Tug Fleet Workshop Summary: sponsored by Alyeska/SERVS and the PWS Tanker Owners at the Valdez Convention Center. (pdf/455KB)

Agency Authority on PWS Tugs. By Harvey Consulting, LLC and Nuka Research and Planning Group, LLC. June 2006 (pdf/100KB)

A July 14, 2008 letter to USCG Rear Admiral Salerno regarding the withdraw of a rulemaking. The rulemaking deals with supplementing a statutory requirement that single-hulled oil tankers in Prince William Sound and Puget Sound be accompanied through those waters by escort vessels. (pdf/2.62MB)

 

2007 PWSRCAC Position on Tug Escort and Response System for TAPS Tankers

Items approved by the board of directors to work into the 2007 tanker c-plan renewal included:

A) All laden tankers in Prince William Sound, including double-hulled tankers, should continue to be escorted by two escorts. A PWS class/ETT tractor tug will be the primary escort and the PRT tractor tug will be the secondary escort.

B) The Hinchinbrook Tug, pending future technological improvements, should always be a PRT. When it is rotated during its maintenance schedule, it should be replaced by an equivalent vessel.

C) The escort system should utilize full response capability per contingency plan and statutory regulations without waivers of prevention requirements.

D) The PWSRCAC recognizes that the above positions can only be met at all times with no more than two laden tankers underway in the system at one time and requests that the TAPS shippers manager the system appropriately.

Items approved by the board as part of the five-year plan included:

A) All tugs in the fleet will be “enhanced.”
B) The Hinchinbrook Entrance tug should be a very maneuverable, ocean-going tug with high bollard pull and salvage capabilities.
C) There will be a one-way zone in the Valdez Arm.
D) There will be a dedicated fire fighting vessel for Port Valdez.

 

Reports and Papers

Expanding the Case for a 10-Tug Minimum Fleet: Review of Scenarios. December 2006: Task 1. By MAC Services, LLC, and Nuka Research and Planning Group, LLC. (pdf/1.1MB)

Adapting Tanker C-Plan Scenario 809 for Gulf of Alaska Response. December 2006: Task 2. By Cape International Inc. for Nuka Research and Planning Group, LLC. (pdf/618KB)

Prince William Sound Escort and Response System: Issues and Policies. December 2006: Task 3. By Nuka Research and Planning Group, LLC. (pdf/647KB)

Tanker lanes and escort zones in Prince William Sound (graphic)

Chronology of Prevention & Response Tugs in Prince William Sound. 2006 (pdf/173KB). Please contact us if you would like copies of reports referenced in this document.

How do they do it in Puget Sound? Find out more about the tug escort system in Washington state in this 2004 report. (pdf/9.6MB)

Prince William Sound Risk Assessment Overview, by Dr. Martha Grabowski, reviews the current state of risk assessment science, presents challenges associated with risk assessments, and provides recommendations for a risk assessment in the sound. June 2005. (pdf/278KB)

Improving the Management of Human and Organizational Errors (HOE) in Tanker Operations, by Bea and Moore. 1993 (pdf/777KB)

 

Issues and Concerns, 2004

PWSRCAC Resolution & Position: The PWS tanker escort system is a critical safety and prevention measure. PWSRCAC strongly supports the continued operation of the escort system in its present configuration.

The Board of Directors passed a resolution in Dec. 2004 in support of maintaining a strong and reliable escort fleet and preserving the practice of requiring two escorts, as currently practiced, for all laden tankers transiting Prince William Sound.
PWSRCAC Resolution (pdf/52KB)
PWSRCAC Position Paper (pdf/1.6MB)

PWSRCAC created these talking points to help aid discussion about tanker escort issues. (pdf/797KB)

PWSRCAC member entities also strongly support the current escort system. Read their resolutions and letters (not all members are represented) (pdfs):

AWRTA (76KB)
Chenega IRA Council (236KB)
Chugach Alaska Corp. (46KB)
City of Cordova (70KB)
City of Homer (84KB)
Kodiak Island Borough (59KB)
Kodiak Island Mayor Association (51KB)
City of Kodiak (51KB)
City of Seldovia (69KB)
City of Seward (49KB)
City of Valdez (51KB)
City of Whittier (44KB)
OSREC (40KB)
PWSAC (89KB)
CDFU (46KB)
Kenai Peninsula Borough (189KB)

 

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