TABLES, PHOTOS, AND ILLUSTRATIONS

                         Listening devices (sitio orig)
                          Leak noise correlator (sitio orig)
                          Schematic of the field setup for the cross-correlation method (sitio orig)
                          General view of experimental leak detection site (sitio orig)
                         Contact points with test pipe (sitio orig)
                         Simulated leaks (sitio orig)
                          Vibration measurement and analysis system (sitio orig)
                         Ground-penetrating radar (sitio orig)
                         Infrared Thermography (sitio orig)
                         Tracer gas (sitio orig)