Description
The cone penetrometer is a truck-mounted device that rapidly penetrates the ground to collect site data. It has been used for approximately 50 yrs for geotechnical applications, but its use in environmental restoration is relatively new. The cone penetrometer rod has a conical tip of up to 2 in. in diameter. It is pushed hydraulically into the ground with a maximum pressure of 80,000 lb. The hole generated by the cone penetrometer retains the outside diameter of the rod and can be grouted as the probe is withdrawn to seal the hole and prevent the escape of contaminants. As the rod progresses into the ground, a computer reads data from sensors located in both the tip and the side of the probe. The cone penetrometer can monitor for contaminants as the probe is advanced or can leave monitors in place as the rod is withdrawn. It can advance through fine-grained soil at a rate of 40 to 50 ft/h. The cone penetrometer is used to install characterization and monitoring wells and may be able to provide chemical and radiological readings from the subsurface. Successful development, demonstration, and deployment of the system as a source detection tool will provide more cost-effective site characterization and remediation by reducing the number of drill holes required, minimizing secondary waste, and reducing potential worker exposure to contaminated materials.
Technical Performance
The system requires a high level of understanding of soil and hydraulics. The cone penetrometer system functions well in a wide range of soils. It can advance through fine-grained soil at a rate of 40 to 50 ft/h.
Cost. Start-Up costs are $500K, Operations and Maintenance costs are $3000/day, and life-cycle depreciation is approximately 10 yrs.
Projected Performance
The cone penetrometer will be adapted for full use in the gravel/cobble subsurface common to arid sites and will require upgrading the thrusting capacity of the truck, reinforcing tools associated with the penetrometer to withstand the additional force, and evaluating the use of vibration to facilitate penetration through gravel.
Waste Applicability
Target contaminants for this technology are carbon tetrachloride, radionuclides, chloro-hydrocarbons, and hydrocarbons in soil.
Status
The status of several different cone penetrometer sensors is given in the table below.
Regulatory Considerations
Regulatory issues vary, depending on the type waste to be characterized. In general, regulations concerning subsurface access characterization well drilling will apply. Ecological impacts are minimal.
Potential Commercial Applications
This technology is very applicable for any commercial environmental characterization need. Industries such as the power, fuel storage and distribution, chemical, refineries, and many others that may have soil or groundwater contamination could benefit by this rapid, extensive, visually and economically attractive, contamination site characterization technology.
Baseline Technology
The baseline technology for site characterization is conventional drilling (auger or mud rotary) and laboratory characterization. The traditional approach lacks detail and precision, is slow in requiring laboratory analysis of contamination, risks cross-contamination, and is potentially hazardous (drilling in waste site). The CPT integrated technique for site characterization is faster, using less costly procedures; has minimum invasiveness, reduced cross-contamination risk; gives greater detail information, except in geophysical logging; and has field analytical ability and real-time data processing.
Intellectual Property Rights
There is no patent on this technology, which has been used for the past 50 years for geotechnical applications.
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References
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