| Use: | Cable tool drilling is well suited for areas contaminated by hazardous substances because it does not use any circulation fluids that could spread contamination. Auger drilling and sonic drilling are the only other drilling methods that do not use circulation fluids. Of these two, only sonic drilling has demonstrated the ability to contain contaminants as effectively as the cable tool. |
Description:
There are primarily two types of cable tool drilling methods utilized in the field:
Cable tool drilling rigs operate by repeatedly lifting and dropping a heavy string of drilling tools attached to a cable into the borehole. The drilling string of a the cable tool consists of five components: (1) consolidated rock is broken or crushed into small fragments and unconsolidated material is loosened by the drill bit or shoe; (2) the drilling stem connects the drill bit to the drilling jars; (3) the drilling jars are used to vibrate the drill bit free of the formation; (4) the swivel or rope socket connects the remaining drill tools to the cable; and (5) the cable is strung over a pulley on the mast to the drill motor.
Hard tooling is the most common form of cable tool drilling and can be used in any formation including basalt. The percussive action (producing a noise level of 53-115 db) of the drill bit crushes the formation. This is accomplished by attaching the cable to an eccentric walking or spudding beam that also serves to mix the crushed or loosened particles with water (generally 10 to 20 gallons if no water is present in the formation) to form slurry at the bottom of the borehole. Periodically, the drilling string is removed and the slurry is removed by a sand pump or bailer. The drive barrel method utilizes the cable tool rig to drive the drill casing into the soil. The soil is pushed inside of the casing and then collected in a split-spoon sampler or core barrel.
Analytes:
| 2. Non-Halogenated SVOCs | 6. Pesticides/Herbicides | 10. Explosives |
| 4. Halogenated SVOCs | 7. Metals | 11. TPHs |
| 5. PAHs | 8. Radionuclides |
Media:
| Soil: | Ground Water: | Surface Water: | Gas/Air: |
| MINIMUM | MODERATE | Not Applicable | MAXIMUM |
A screen must be set before a water sample can be taken for most conditions. Samples obtained using hard tooling are low in quality because liquids are added and because the cuttings are pulverized. In addition, since water has flushed the sample, identification of contaminants could be difficult. Sample quality using the drive barrel technique is far superior to that of the hard tooling method because no water is added to the borehole.
| Maximum Depth: | <5000 feet. |
| Production Rate: | Sample is available after an extended wait. Drilling rates range from 1.5 to 2.5 feet per hour for bedrock and dense tills, 2.3 to 3.3 feet per hour for gravel and tills, and 3.5 to 4.5 feet per hour for silts, clays, and sands. |
| Investigation Derived Waste Volume: | Medium volume of waste. |
| Technology Status: | Commercially available and routinely used field technology. |
| Certification/Verification: | Technology has not participated in CalEPA certification and/or CSCT verification program. |
| Relative Cost per Sample: | Mid-range expense. Drilling costs will be higher for hard tooling as heavy wall or large diameter casing might be required. Rigs are simple in design and are easily maintained. One person can execute operation. Cable tool rigs have lower operating and capital costs when compared to air rotary drilling. |
Limitations:
ASTM Standards:
| D 5875 - 95 | Use of Cable-Tool Drilling and Sampling Methods for Geoenvironmental Exploration and Installation of Subsurface Water-Quality Monitoring Devices. |
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