Federal regulations (specified in 40 CFR 280-281) required that by December 22, 1998, all underground storage tanks (UST) containing petroleum products must meet the requirements for leak detection, spill and overfill protection, and corrosion protection. To help DoD bring its USTs into compliance, the U.S. Army Construction Engineering Research Laboratories (USACERL), in conjunction with RedZone Robotics, Inc., developed a remote, robotic, ultrasonic UST inspection system named Fury to reliably assess the condition of USTs. Under this ESTCP project, Fury was: (1) successfully validated in a UST at Fort Lee, VA, and (2) successfully demonstrated in three USTs at Hunter Army Air Field (a sub-unit of Fort Stewart, GA).

Demonstration Results

Utilizing ultrasonic transducers that were mounted on a sensor sled, Fury provided faster inspections and more reliable data than conventional manual inspection methods. It identified the most severely pitted tank wall regions and avoided the expense and safety issues associated with confined space entry. The quantity, accuracy, and usefulness of data obtained from Fury inspections were also superior to those of data obtained from manual tank inspection methods. Fury obtained approximately 90,000 measurements per hour of tank wall thickness at over 95 percent of cylindrical tank-wall or end-cap locations. An inspection rate of 250 ft2/hr was achieved. Fury inspection of a typical 30,000 to 50,000 gallon UST was completed in less than one day.

Implementation Issues

Fury is designed to fit through an existing small diameter pipe mounted in a UST, which mitigates invasive tank entry during assessment and allows for non-destructive assessment. Significant cost savings can be realized for each tank that is determined to be suitable for upgrade. The results of this ESTCP project indicate a payback of less than 2.5 years for a Fury inspection system costing $100,000, assuming a per-tank assessment cost between $600-$1,200, which is $2,000 to $4,000 per tank less than the estimate for conventional manual invasive methods. The potential cost savings of not replacing 10 percent of the nationwide UST inventory are as high as $10 billion.

The results of Fury UST condition assessments can be used to make better informed management decisions regarding UST upgrade versus replacement. Fury ultimately is intended for deployment in tanks containing fuel, in which the headspace above the fuel is filled with a protective blanket of inert gas, thus avoiding interruption of normal operations. Safety certification for this procedure currently is being pursued. Fury can be used for ongoing UST condition assessment and assessment of aboveground tanks. Additional applications include underwater inspection of ship hulls, oil platforms, submersed sheet piling, locks and dams, as well as potential nuclear applications. The Fury prototype was tested in the configuration intended for future production. Therefore, there are no scale-up issues. (Project Completed - 1999)