4.1x00a0;Cable-tool rigs (also referred to as churn rigs, water-well drilling rigs, spudders, or percussion rigs) are used in the oil fields and in the water-well industry. The Chinese developed the percussion method some 4000 years ago.
4.2x00a0;Cable-tool drilling and sampling methods may be used in support of geoenvironmental exploration and for installation of subsurface water-quality monitoring devices in both unconsolidated and consolidated materials. Cable-tool drilling and sampling may be selected over other methods based on its advantages, some of which are its high mobility, low water use, low operating cost, and low maintenance. Cable-tool drilling is the most widely available casing-advancement method that is restricted to the drilling of unconsolidated materials and softer rocks.
4.2.1x00a0;The application of cable-tool drilling and sampling to geoenvironmental exploration may involve sampling unconsolidated materials. Depth of drill holes may exceed 900 m [3000 ft] and may be limited by the length of cable attached to the bull reel. However, most drill holes for geoenvironmental exploration rarely are required to go that deep. Rates for cable-tool drilling and sampling can vary from a general average of as much as 7.5 to 9 m/h [25 to 30 ft/h] including setting 200 mm [8 in.] diameter casing to considerably less than that depending on the type(s) of material drilled, and the type and condition of the equipment and rig used.
4.2.2x00a0;The cable-tool rig may be used to facilitate the installation of a subsurface water-quality monitoring device(s) including in-situ testing devices. The monitoring device(s) may be installed through the casing as the casing is removed from the borehole. The sand line can be used to raise, lower, or set in-situ testing device(s), or all of these. If necessary, the casing may also be left in the borehole as part of the device.
1.1x00a0;This guide covers cable-tool drilling and sampling procedures used for geoenvironmental exploration and installation of subsurface water-quality monitoring devices.
1.2x00a0;Several sampling methods exist for obtaining samples from drill holes for geoenvironmental purposes and subsequent laboratory testing. Selection of a particular drilling procedure should be made on the basis of sample types needed and geohydrologic conditions observed......