A conduit is connected to the interstice between an outer and inner wall of a storage tank or the liner thereof and may be used to monitor the integrity of the interstice. The conduit comprises a coupling in fluid communication with the interstice, a tube connected at one end to the coupling and having a length sufficient to extend into a riser pipe of the tank. The conduit may also include a bushing holding the tube apart from the tank and providing for the variable positioning of the tube with respect to the tank. A method of monitoring the integrity of the interstice uses monitoring equipment connected to the conduit.