Current and proposed state and federal regulations require that underground storage tanks used for the storage of hazardous substances meet certain environmental safety requirements. In particular, these environmental regulations require that the underground storage systems include a primary containment unit and a secondary containment unit. Moreover, the primary and secondary containment units are required to comply with the environmental standards that require underground storage tank systems to be product tight. The term “product tight,” for purposes of these environmental regulations, is generally defined as impervious to the substance that is contained to prevent seepage of the substance from the primary containment unit. Moreover, for a tank to be product tight, the tank cannot be subject to physical or chemical deterioration by the contained substance over the useful life of the tank. Further, these regulations require that owners or operators of an underground storage tank system with a single-walled component located within 1,000 feet of a public drinking water well implement a program of enhanced leak detection or monitoring.
One known method of monitoring leaks disclosed in U.S. Pat. No. 6,489,894, entitled “Leak Detection Device for Double Wall Pipeline Systems and Container Systems,” uses a leak detector with a vacuum pump including a pressure-dependent switch and an alarm device to detect leaks in a double-walled pipeline or container system. The disclosed leak detector is adapted to simultaneously monitor several containers connected to a collecting main and a vacuum pump by vacuum lines. Each monitored container incorporates a vacuum connector or valve to fluidly connect a control space to the leak detector. Each vacuum line has a first liquid lock arranged at the vacuum connector to block liquid that has leaked into the vacuum lines from a leaky container from penetrating into the control spaces of the leak-free containers. A second liquid lock is arranged in the collecting main to prevent liquid from entering the vacuum pump. While this method can detect leaks within the control space of a container, it is a mechanically complex system requiring a great deal of materials and set-up time.
Other methods of monitoring secondary or interstitial spaces are well known in the art and include continuous leak detection using both pressure and brine solution monitoring techniques to determine the presence or absence of leaks between the storage system and the surrounding environment. However, to effectively calibrate all of these known methods and systems for operation, a great deal of set-up time and system knowledge is required. Specifically, to configure these monitoring systems for operation, the user must enter the volume of the secondary or interstitial space to be monitored, which requires a detailed knowledge of the layout and the configuration of the double walled piping and containers used in the underground storage system.