tanker escort system report to the board of the pwsrcac

Tanker Escort System Report to the Board of the PWSRCAC

1. Overview of Tanker Escort System

Immediately after the Exxon Valdez oil spill in 1989, Alaska’s governor passed an Executive Order requiring all laden, single-hull tankers transiting Prince William Sound to be accompanied by two escort vessels instead of only one. This was reinforced in federal law when the Oil Pollution Act was passed in 1990. Federal rulemaking by the US Coast Guard concluded the regulatory process in 1994; since then the Sound’s world-class escort system has continued to be refined in terms of the escort vessels’ roles and respective technical requirements.

Two high-powered tugs escort each laden tanker through the sound. The Alyeska Pipeline Service Company’s Ship Escort Response Vessel System (SERVS), paid for by the Trans Alaska Pipeline System (TAPS) tariff, includes a varied fleet of escort and response vessels.

The SERVS fleet’s key functions are to: identify any indication that a tanker is having problems, assist the tanker as needed, and provide first response in the event of a spill. Over the years, the tanker escort system has evolved to require escort coverage from the Valdez Marine Terminal through Hinchinbrook Entrance (and a sentinel on station until the laden tanker is more than 17 miles seaward of Cape Hinchinbrook), more powerful and maneuverable tugs, and improved procedures.

Importance of the Escort System

The SERVS fleet safeguards the Sound 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 tug, the escorts are equipped for spill response, firefighting, and tanker assists in case of inclement weather, icebergs, and varied geography.

Future of the Escort System

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. PWSRCAC has the following concerns:

• During 2005, the possibility of reducing the number of escort vessels required for laden tankers in the Sound was discussed.

• Federal statutes and regulations that require the tanker escort system specify that escort tugs are required for single-hull, laden tankers only. Thus, the requirement that two escorts attend every tanker will effectively sunset with the transition to a double-hull tanker fleet. Federal law mandates this transition nation-wide by 2015, but industry estimates the TAPS-tanker fleet will be comprised entirely of double-hulls as early as 2007.

• The State of Alaska Contingency Plans also require two escorts. These plans are up for renewal in the fall of 2007, and this requirement could easily be removed.

September 15, 2006 of 13


Escort System for Different Sections of the Sound.



Various Towing Techniques for Tethered Tugs – top graphic depicts ETT Voith Tractor Tug, bottom depicts PRT Z-Drive Tractor Tug



Various Towing Techniques for Tethered Tugs, continued – top graphic ETT Voith Tractor, bottom graphic PRT Z-Drive Tractor



2. Functional Requirements of Escort and Response Tugs

Escort and response tugs are designed to fulfill multiple tasks within the SERVS system as described in the VERP.

Anchor Handling

Tugs set and retrieve deep-water mooring systems for response barges and hatchery protection sites. Similar moorings may be handled during response operations. Used for maintenance within the SERVS fleet.

Docking/ undocking Tankers

Self-explanatory. Tugs must have suitable maneuverability and horsepower to assist tankers at the VMT. The State requires two tugs for docking/undocking tankers under 150,000 dwt and three tugs for tankers larger than 150,000 dwt.

Fire Fighting Vessel must be equipped with Marine Fire Fighting systems, such as elevated fire monitors, which are adequate for fighting fires on board tankers berthed at the VMT.

Escort Response

Vessel

Vessels must be equipped with skimmers and able to store recovered oil on board. Required in federal regulations, the Tanker C-Plan, and the VERP.

Standby Vessel

Vessel is in attendance with a response barge any time the barge is engaged in spill recovery, drills, or training exercises. The standby vessel must be able to accommodate all persons on the response barge in addition to its own crew. This requirement is defined in the VERP and the vessel must meet the standards of 33 CFR 143.405.

Ice Scout Vessel

Performs reconnaissance of the tanker escort route and adjacent areas to collect and disseminate real-time information about ice conditions during tanker transit.

Primary Escort Tug

Tethered to tanker during navigation from the VMT to Buoy 9, after which the primary escort releases its tether and provides close escort. Tug must have sufficient horsepower, bollard pull, and maneuverability to achieve a “save” of a distressed tanker in all sections of its transit. Required in the VERP.

Secondary Escort Tug

Second tug of the two-tug escort team required to assist a laden tanker through the escort route. Must be of sufficient horsepower, bollard pull, and maneuverability to achieve a “save” of a distressed tanker and be able to replace the primary escort as the tethered tug in the event of a system malfunction. Required in the VERP.

Hinchinbrook Tug

Tug is stationed in the vicinity of Hinchinbrook Entrance to assist a sentinel escort when tankers in ballast are transiting the Entrance. Also stationed to assist when laden tankers are transiting the Entrance in either direction. The Hinchinbrook tug must be on station any time a laden tanker is in the Gulf of Alaska within 17 miles of Cape Hinchinbrook. Tug must have high horsepower and bollard pull, a tow winch with suitable cable and gear for ocean towing, and a large, deep-draft hull with sufficient freeboard to maintain watertight integrity and stability in rough weather conditions. Required in the VERP.

Sentinel Escort Tug

An escort tug stationed in the Northern or Central Sound and at Hinchinbrook Entrance to assist tankers. Must be of sufficient horsepower and bollard pull to “save” a distressed tanker in the more open areas and having onboard skimming equipment and storage for recovered oil. Required in the VERP.



3. Capabilities of the Current Fleet

The current SERVS fleet includes a variety of vessels with varied capabilities.

Tugs in the SERVS Fleet

A. Tractor Tugs. Typically fulfill functions as primary and secondary escorts.

Class: PRT (Prevention and Response Tug) Vessels: Alert, Aware, Attentive Propulsion: Z-drive reverse tractor tugs BHP: 10,192 bhp Characteristics: High maneuverability and bollard pull; sufficient freeboard and draft and aft-mounted tow winch to provide rough weather towing in Gulf of Alaska.

Class: ETT (Enhanced Tractor Tug); also called “PWS Class” Vessels: Nanuq, Tan’erliq Propulsion: Voith Schneider Cycloidal tractor tug BHP: 10,192 bhp Characteristics: Exceptional maneuverability and bollard pull; capable of applying both high bollard pull in the direct mode and high bollard pull combined with “hull drag forces” in the indirect mode save distressed tanker.

B. Conventional Tugs. Initially constructed for, and used in, line-haul ocean and coastwise towing. Fail to meet requirements for primary and secondary escort functions due to lower maneuverability, inability to work in the indirect mode, and vulnerability to getting “in irons” (heeling over, taking on water, or flipping). Inadequate freeboard aft. Propeller thrust is directed fore or aft, rather than also laterally like the tractor tugs, which are capable of directing propeller thrust over a 360 degree range.

Class: Theriot Vessels: Sea Voyager BHP: 7,200 bhp Characteristics: Kort nozzled fixed propellers; approved as maintenance relief for Hinchinbrook tug.

Class: Invader

Vessels: Bulwark, Stalwart BHP: 7,200 bhp Characteristics: Fixed, open propellers.

Class: Swift

Vessels: Pathfinder BHP: 5,750 bhp Characteristics: Fixed, open propellers.

C. Utility Tug.

Class: Offshore tug/supply vessel; also called “utility class” Vessels: Endurance



Characteristics: Maneuverability for docking barely adequate because of length, hull configuration, and kort nozzled propellers detracting from maneuverability.

Functionality of the Current SERVS Fleet



4. Update on Escort Vessel Fleet Analysis

The May 2006 Board presentation listed next steps for analysis of the escort vessel fleet. These are listed here with updates on project status.

Task Update

Finalize tug escort system chronology paper.

Draft on PWS RCAC website.

Work with agencies and RPG to monitor consistency in VERP and C-Plan updates

Project team is now involved in the rewrite of these documents to ensure consistency between state and federal requirements and within the documents themselves.

Complete paper documenting history of BAT for escort system

Harvey Consulting, LLC and Nuka Research and Planning Group, LLC are in final stages of completing this scope of work.

Complete analysis of agency authority over escort system (state vs. federal)

Harvey Consulting, LLC and Nuka Research and Planning Group, LLC are in final stages of completing this scope of work.

Research and report on circumstances under which an attending tug may be released from its response barge during a spill response

Dave Eley and Nuka Research and Planning Group, LLC are in final stages of completing this scope of work.

Analyze, test, and either validate or challenge the logistics rules (assumptions) used justify the 1995 PWS Settlement and 10-tug fleet case

Draft report from Alaska Maritime Services currently under review for finalization.

Describe functions required of tugs and assess each type of tug’s capacity to achieve these functions

Draft report from Alaska Maritime Services currently under review for finalization.

Complete literature review and analysis of role of human factors in spills from vessels

Nuka Research and Planning Group, LLC has completed An Assessment of the Role of Human Factors in Oil Spills from Vessels. The paper has been peer reviewed, and was approved by the Executive Committee on September 8, 2006 for posting of PWSRCAC website and release to industry. The paper concludes that the replacement of single-hull tankers with double hulls cannot prevent the human or organization errors known as “human factors” that lead to accidents. This can, however, prevent or reduce the severity of a spill resulting from a tanker accident. Therefore, this paper reinforces the need to continue the two-escort system as currently required for all laden, single-hull tankers.

Obtain clarity on tanker speed restrictions

RCAC staff is working with the US Coast Guard to clarify tanker speed limits for the entire tanker escort route. RCAC has requested that the Coast Guard provide written documentation to clarify the issues previously raised about Buoy 9: maintaining the 8 knot speed restriction but clarifying the boundaries of this reduced speed for tankers and establishing a one-way traffic zone in this area for VTS rules.

Oversee SERVS tug data collection effort

RCAC staff continues to monitor the SERVS tug data collection and reports with the objective of comparing RCAC AIS-collected data with the SERVS data to identify any



anomalies for report to the C-Plan team.

Remaining projects to be sourced:

• Expand the 10-tug fleet case (examine the “upside tug fleet” needs or potential needs under various scenarios)

• Examine the tug, response barge, and manning requirements for the post-72 hour response scenarios and out-of-region response requirements.

• Compile all source materials used in escort system-related projects, including those described here, for a comprehensive analysis and development of recommendations to the Board of Directors



5. Remaining Questions for Discussion

Could a tanker escort system with fewer than 10 tugs provide adequate safety and reliability?

Harvey Consulting, LLC’s December 2005 Tug Workshop Report found that the minimum number of tugs required for response is 10. The RPG has communicated the following to PWSRCAC in recent months:

After careful consideration of the information gathered to date, the Plan Holders have decided not to pursue a C-plan amendment to remove tugs from the TAPS system at this time.

--RPG to PWSRCAC on April 20, 2006

No proposed changes to the escort system are envisioned prior to completion of the PWS Risk Assessment. No proposed changes to the number of tugs in the SERVS fleet are planned prior to completion of the 2007 PWS Tanker Oil Discharge Prevention and Contingency Plan renewal.

--RPG to PWSRCAC on June 5, 2006

RCAC’s letter suggests that the Escort Program should be changed. As previously discussed, any change to the manner in which tankers are escorted in PWS should be supported by, among other things, a risk assessment. . .Having reliable, tested and approved systems in place, including robust personnel training programs, to prevent accidents has been and will continue to be a key to success.

--RPG to PWSRCAC on August 16, 2006

Is it prudent to reduce or eliminate the tanker escort system when the tanker fleet is comprised entirely of double hulls?

Nuka Research and Planning Group,LLC’s August 2006 report, An Assessment of the Role of Human Factors in Oil Spills from Vessels, concludes that accidents due to human factors will continue regardless of the use of double hulls. In the event of a tanker accident, the redundant hulls may prevent oil from spilling to water or reduce the amount spilled; however, the hulls do not prevent accidents from happening. Thus, the importance of escorting tankers to prevent groundings or collisions resulting from human errors is not diminished. It is estimated that up to 80% of marine accidents may be attributed to human factors.

Does the escort tug system meet the State’s Best Available Technology (BAT) requirements?

BAT for the tanker escort route consists of an ETT as a primary escort and PRT as secondary escort. These tractor tugs are the only ones adequate for the escort roles, as escorts are required by the State’s BAT assessment to be able to make a “save” of a distressed tanker. All other tugs in the fleet would unable to make the save in weather conditions exceeding moderate. SERVS still dispatches an occasional conventional tug as the secondary escort, thus failing to meet the BAT requirement. This is supported by the computer modeling of the Glosten ARCO Report, the Disabled Tanker Towing Study, emergency towing tests and trials, and other documents.



6. PWSRCAC Staff Recommendations to the Board of Directors

PWSRCAC staff makes the following recommendations to the Board of Directors:

1. Continue to support staff efforts to revise both the VERP and the Tanker C-Plan to specify BAT tugs (PRT Z-drive tractors and ETT Voith tractors) in all sectors of the tanker escort route.

2. Justify the composition of the escort/response tug fleet such that each required function is filled by a tug with adequate capability. This should be based on the comparison of performance capabilities of the various tugs in the fleet that is provided here. Alaska Maritime Services’ report, when finalized, will contain a more detailed comparison.

3. Negotiate with RPG for an immediate upgrade in the escort/response tug fleet by replacing the Theriot class Sea Voyager with a Protector class Voith tractor tug Guard or Protector, or similar tractor tug of even higher horsepower.

4. Negotiate with RPG for a more gradual, phased upgrade in the escort/response tug fleet by replacing the remaining conventional tugs with Z-drive or Voith tractor tugs.

5. Emphasize to RPG and SERVS that the Dispatcher/SERVS Duty Officer should prioritize the use of the BAT tractor tugs for both primary and secondary escort roles, and dispatch escort tugs accordingly.


tanker escort system report to the board of the pwsrcac

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