Abstract: Bentonite, and other water-sensitive materials in granulate form, are introduced into boreholes. The material is borne into the borehole through a conduit, in which a flow of air (or nitrogen) not only transports the material but also keeps water that may be present in the borehole from entering the conduit. The materials are contained, above ground, in hoppers arranged to feed in parallel into the conduit. Material from a selected hopper enters via a respective valve into the conduit. The hoppers are pressurized to ensure the moving gases in the conduit do not enter the fall pipe. Having turned the air on, the technician lowers the conduit to the bottom of the borehole; then he opens the valve to admit the selected filler material; then he withdraws the conduit gradually and progressively up the borehole, depositing the material. The conduit is of flexible material, and can be held in the hand, to assist in sensing the flow of material.

Abstract: The probe (20) includes a conductivity sensor (38) and an optical sensor (39) for detecting the depth of a layer of oil, gasoline, etc floating on the surface of water in a well. A battery (60) is included in the probe, and a resistor (R1) is provided in series with the conductivity sensor. When the probe is in oil, both sensors are OFF, and no voltage is detectable at the surface; when the probe is in air, the optical sensor is ON and the conductivity sensor is OFF, so that a maximum voltage is detectable at the surface; and when the probe is in water, the optical sensor is OFF and the conductivity sensor (with its resistor) is ON, so that an intermediate voltage, as set by the value of the resistor, is detectable at the surface.

Abstract: One electrode of the probe is its tubular outer sleeve (3), and the other is its central rod (4). The insulators (9,16) separating the two are attached rigidly to the central rod, whereby the outer sleeve may slide off the probe for cleaning and servicing purposes. The outer sleeve is held in place simply by friction from the O-ring seals (12,30). When the sleeve is removed, the central rod, insulators, etc., remain as a structurally complete sub-assembly. Electrical contact with the outer sleeve is made through an expandable canted coil spring (20), mounted on an insulator. The central rod is formed with a massive center section (7), for weighting the probe. The probe is supported on a graduated tape (36), in which are embedded the electrical leads (38) to the probe. The leads are securely attached and sealed in place by means of heat-shrinkable material (50), which is wrapped around the leads, heat-shrunk, and compressed into a pocket (27).