penetrometer technology (CPT) is a method of providing real-time
data for use in characterizing the subsurface, as opposed to older
analyzing subsurface conditions in the laboratory. It consists of a
that is hydraulically pushed into the ground at up to 40,000 pounds of
pressure. Sensors on the tip of the cone collect data. Standard cone
penetrometers collect information to classify soil type by using
measure cone-tip pressure and friction. CPT is often used in
Hydropunch tests, which use the CPT holes to extract groundwater
for laboratory analysis. An innovation of the CPT (i.e., the wireline
allows multiple CPT tools to be interchanged during a single
without withdrawing the CPT rod string from the ground.
developed to collect information about soil characteristics, as sensor
technology was developed CPT also became a platform for collecting
about a variety of contaminants.
Recent advances in sensor technology have expanded cone penetrometer
capabilities to detect the presence of petroleum hydrocarbons.
Sensors are being tested or demonstrated for the detection of other organics,
compounds, metals, radioactivity,
explosives, and soil moisture.
the advantage of using CPT is that sampling costs less and is
shipping samples to a laboratory. CPT locations can be altered as
analyzed, thus providing the operator with increased flexibility. It
noted, however, that when certain sensors are used, results may have to
by laboratory analysis.
cannot be used at some sites due to high soil density.
sensors are now used as screening tools that provide initial site
characterization data. The data is confirmed by collecting samples that
analyzed in the laboratory. This is due to limitations in sensor
and it will likely diminish in importance as the technology improves.
is useful on sites that contain unconsolidated sediments (e.g., soil
that are not cemented together). On the other hand, sites with large
rock or cemented layers are difficult to penetrate.
sensors, such as lasers, that require a lens may be hampered by fouling
lens due to a reaction to dust.
may be necessary if the CPT comes into contact with contaminated
is a characterization tool used to identify the geologic, hydrologic
and chemical features of a site. It can be applied to all sites. It is
contaminant specific. CPT is generally applied to depths up to 150
feet, but it
has been used as deep as 300 feet.
was introduced in 1934 in the Netherlands. Actual electrical
sensors were not developed until 1948, and they were not widely used
1960s. By the 1980s, the cone penetrometer was commonly used for
applications, with at least a dozen companies routinely providing the
technology. Research was initiated in the late 1980s to develop other
Resources and Demonstrations
successful demonstration was performed at Sandia National Labs (SNL) in
Mexico using an integrated Laser Induced Breakdown Spectroscopy (LIBS)
Penetrometer Technology (CPT) system to rapidly analyze (currently less
hours) the heavy-metals
content of the subsurface soils. The CPT-deployed LIBS using a
laser pulse. The soil absorbs the energy and heat. Elemental analysis
conducted via an optical fiber. The CPT/LIBS system was successfully
demonstrated. (LIBS technology developed by Los Alamos National
was successfully field tested to detect chromium and beryllium in
soils. However, one of the shortcomings of LIBS is the calibration/data
analysis procedure requires a knowledge of soil type prior to effective
for a description of a cone penetrometer with a Raman probe used at
See http://www.osti.gov/bridge/servlets/purl/585514-XNxjsb/webviewable/ for determining migration and distribution of contaminants using multiple sensors on the cone penetrometer.