Document Author: Dr. Craig H. Benson

Review of Pilot Study of Secondary Containment System at the VMT West Tank Farm Conducted July 2024

Full title: Review of Electrical Leak Location and Electrical Resistivity Tomography Pilot Study of the Secondary Containment System at the Valdez Marine Terminal West Tank Farm Conducted July 2024

Drs. Scalia and Benson’s report summarizes the findings from Alyeska’s pilot study using electrical leak location to detect leaks in the Secondary Containment System. The study was conducted in July 2024. The report also includes Scalia and Benson’s recommendations for Alyeska’s larger scale testing plan for the East Tank Farm.

Methodologies for Evaluating Defects in the Catalytically Blown Asphalt Liner in the Secondary Containment System at the Valdez Marine Terminal

The report also describes a statistical method that was developed to compute the total number of defects (holes, cuts, cracks, or other features that fully penetrate the CBA liner and provide a pathway for liquid flow) in a secondary containment liner with a specified degree of statistical confidence based on outcomes from inspection over a portion of the liner. The statistical methodology was also used to demonstrate how much area of liner needs to be inspected to identify the defects in the liner. Charts are provided that can be used to determine the minimum area of evaluation to obtain an assessment of liner defects with an acceptable percentage of missed defects and an acceptable probability of mistake.

Additional details can be found in the article: Electric current can find damage in underground liners

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