Abstract: A method and system for detecting and identifying location of leaks in an above-ground storage tank (AST) bottom or wall is provided. The method employs a temporary liner on top of the tank bottom or at the interior of another tank surface capable of holding a vacuum. The temporary liner is installed on the top (interior) side of the surface, sealing the liner to the shell and any potential penetrations such as columns. A temporary spacer may be employed to help ensure the liner itself does not seal well to the bottom. A vacuum is pulled between the liner and the tank surface. After the vacuum is pulled, a portable acoustic device is utilized to target noise generated by air entering the vacuum evident of a gas or liquid leak.