Abstract: Vertical migration of a plume of subsurface contamination in the vadose zone to the groundwater is prevented by forming and maintaining one or more desiccation layers in the vadose zone in or above a layer of contamination. Horizontal barrier layers are produced by injecting dry air at a specific elevation in one borehole and removing the air at another borehole. These horizontal layers act as an impermeable barrier to the vertical migration of dissolved contaminants.

Abstract: A method and an apparatus for finding the location of one or more holes in a fluid flow system such as pipe, duct, or conduit using one or more tracers that interact with or can be chemically or physically differentiated from those of the liquid or gas contents located outside the system and pulled back into the system when the system is placed under a vacuum. The preferred embodiment of this detection and location method uses one or more interactive tracers that are injected into a pipe or duct that may be leaking at one location and then monitor the concentration of these tracers at the same or another location in the pipe or duct. Detection and location are accomplished by analysis of the characteristic features of measured curves of tracer concentration. Various types of interactive tracers may be used, including partitioning and reactive tracer gaseous tracers.

Abstract: A method and an apparatus for detecting, locating, and quantifying explosive materials and devices, and naturally occurring and man-made dangerous or hazardous biological and chemical materials and devices in ducts or piping systems, or other fluid flow systems in buildings such as residential, office, industrial, and power plants, transportation systems such as ships, airplanes, subways, and trains, and various types of infrastructure such as dams, tunnels, or bridges, and in the rooms, compartments, enclosures, containers, or difficult to access areas in these buildings, transportation systems, and structures. The preferred embodiment of this detection and location method uses a conservative tracer and one or more interactive tracers that are injected into the duct or area to be searched at one location and then monitored at the same or another location in the duct or area.

Abstract: A method and an apparatus for detecting, locating, and quantifying contamination in a fluid flow system like a pipe or duct. This characterization technique uses a conservative and one or more interactive tracers that are injected into the fluid flow system and then monitored at another location in the system. Detection, location, and quantification are accomplished by analysis of the characteristic features of measured curves of tracer concentration.