Pilot test evaluates testing methods for buried liners

How do you detect damage underground? The Council, Alyeska, and the Alaska Department of Environmental Conservation, or ADEC, have been trying to answer that question. The results from a recent pilot test are providing direction to help ensure that oil will not leak through the secondary containment liners under the storage tanks at the Valdez Marine Terminal.

Finding flaws in an underground liner

Last summer, Alyeska conducted a pilot test for locating damage in the special asphalt liners that surround the crude oil storage tanks at the terminal.

The liners are part of a system surrounding the tanks that is designed to prevent oil from leaking into the environment. The liners are difficult to examine because they are buried under several feet of earthen fill. Digging them up for inspection is expensive, time-consuming, and historically has caused damage.

Since the liners were installed nearly 50 years ago, only a small percentage has ever been uncovered and evaluated for damage. When sections have been uncovered, holes or cracks have been found about 19% of the time.

Both Alyeska and the Council have been looking for a method that can determine whether there are cracks or faults in the liner, and if so, where they are located, without having to dig, per requirements set by ADEC.

Results from pilot test

Of the methods that were tested last July, electrical leak location was determined to be the most feasible. This type of survey is done by applying electric currents to the ground outside the liner and measuring electric currents on the surface of the fill inside the liner. A solid liner would block the currents. Holes or cracks would allow the current to flow through. The currents that flow through the liner can be detected from the surface, allowing technicians to create a map of damaged areas.

Further analysis to come

Alyeska conducted this pilot test in preparation for a larger-scale test. When approving the last update to Alyeska’s oil spill contingency plan, ADEC placed a condition on the plan’s approval, requiring that Alyeska conduct further analysis of the liner. The timeline for these additional tests is yet to be determined.

How much of the liner needs to be tested?

The Council hired Dr. Craig Benson, Distinguished Professor Emeritus of the University of Wisconsin-Madison, and Dr. Joe Scalia, Associate Professor of Civil and Environmental Engineering at Colorado State University, to weigh in on the pilot test results. They determined that when the large-scale testing is done, at least 20% of the liner needs to be examined to be able to confidently estimate the frequency and size range of defects in the liner.

Details in the report:

Find out more about the pilot test and the expert’s recommendations in the report:

Science Night 2023 – Videos now available

Systems and Methods: Connecting across the Exxon Valdez oil spill region

Science Night is an annual event hosted by the Prince William Regional Citizens Advisory Council. Topics focus on research related to the safe transportation of oil through Prince William Sound.

Individual presentations can be viewed below, or you can view the full playlist directly on the Council’s Youtube Channel: Science Night 2023

On this page:

  1. Let the Hydrocarbons in Prince William Sound Talk
  2. Forage Fish Update
  3. Tsumani/landslide hazards in Prince William Sound
  4. Alaska Spill Response Wildlife Aid

Let the Hydrocarbons in Prince William Sound Talk: 30 years of Environmental Monitoring through PWSRCAC’s LTEMP

Presenter: Dr. Morgan Bender, Senior Scientist, Owl Ridge Natural Resource Consultants, Inc.

The PWSRCAC’s Long-Term Environmental Monitoring Program (LTEMP) is one of the longest-standing hydrocarbon assessment programs of its kind and provides us with annual data on how and where hydrocarbons enter Prince William Sound and the potential effects they may have on the marine ecosystem. Morgan, an Alaska-based ecotoxicologist, will lead us through the 30-year LTEMP investigative process and major findings to inform and excite Science Night participants on LTEMP’s past, present, and future.

View Let the Hydrocarbons in Prince William Sound Talk directly on YouTube.


Forage Fish Update

Presenter: Scott Pegau, Research Program Manager, Oil Spill Recovery Institute

Forage fish provide a critical link between plankton and large predators like birds, mammals, and other fish. Pacific herring, sand lance, capelin, and juvenile pollock are a few of the many forage fish in PWS. Most of the information we have on forage fish is associated with herring because of its historic commercial importance but there is some information on other species. This presentation takes a look at some of the existing research into forage fish in Prince William Sound.

View Forage Fish Update directly on YouTube.


Advancing our understanding of tsunamigenic landslide hazards in Prince William Sound, Alaska

Presenter: Dennis M. Staley, Research Physical Scientist, U.S. Geological Survey – Alaska Volcano Observatory

Exposure to landslide and tsunami hazards are a part of life for those who reside in the seaside communities of coastal Alaska and the people who work or recreate in coastal waterways. Recently, the recognition of the landslide-generated tsunami hazard posed by the Barry Arm landslide in northwestern Prince William Sound has attracted considerable attention in the public and media, at local, state, and federal governments, and in the scientific community. This presentation focuses on the ongoing effort to assess hazard and warn for a tsunami produced by the Barry Arm landslide, and on scientific investigations into the prevalence of this type of natural hazard at other locations in Prince William Sound.

View Advancing our understanding of tsunamigenic landslide hazards in Prince William Sound directly on YouTube.


Alaska Spill Response Wildlife Aid

Presenter: Bridget Crokus, Deputy Oil Spill Response Coordinator, USFWS Alaska Region

Protecting fish, wildlife, and their habitats is a primary response objective after an oil spill. First-hand accounts of wildlife in or near an oil spill are invaluable to a successful wildlife response. Bridget will present the Alaska Spill Response Wildlife ID Aid, a tool developed to help spill responders “take a wildlife minute” and record the wildlife they see.

View Alaska Spill Response Wildlife Aid directly on YouTube.

Annual Report now available

Front cover of the report. Image is of a rocky beach in Prince William Sound covered with mussels and other tidal critters. Mountains and ocean in the background. Clicking on the image will download a PDF of the report.The Council’s annual report, Year in Review 2022/2023, is now available. This report covers the many programs and projects we’ve been working on over the past year, such as oil spill prevention and response, environmental monitoring, oil spill contingency plans, operations at the Valdez Marine Terminal, invasive species monitoring, our outreach efforts, and much more. Highlights from this year include:

  • An assessment of risks and safety culture at the Valdez Marine Terminal
  • Ensuring the adequacy of secondary containment liners for the terminal’s crude oil storage tanks
  • Supporting solutions for sustainable funding for state spill
    prevention and response
  • Improvements to how the Council monitors weather and sea currents in our region
  • Monitoring oil spill drills and exercises
  • Reexamining the Council’s position on use of dispersants in our region

Download: 2022-2023 Annual Report

New station at Copper River Delta to monitor for high winds

The Council recently sponsored a new addition to the weather station network. The new station was placed near the mouth of the Copper River Delta on a small island known as Kokinhenik Bar.

The Copper River Valley can funnel high winds when there is a high-pressure system over interior Alaska and a low-pressure system over the Gulf of Alaska. Oil-laden tankers travel shipping lanes a little over 23 miles away, so this information will aid in the safe transportation of oil, and an important asset in the event of a spill.

A link to the data from this weather station, along with other weather tracking resources is available on our website: Tracking Weather for the Safe Transportation of Oil

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