Site Characterization
and
Analysis Penetrometer System (SCAPS)
Description
The
Site Characterization and Analysis Penetrometer System (SCAPS) is a
rapid
in-field soil and groundwater analysis system
that provides
cost-effective characterization of soil conditions to depths of up to a
hundred
feet or more. SCAPS uses a truck-mounted cone penetrometer system to
directly push an
instrumented probe into the ground for rapidly characterizing soil
types and
detecting and delineating the presence and extent of subsurface
contamination.
A variety of sensors can be attached to the probe to detect different
compounds. Sensors to detect petroleum compounds and metals have been
demonstrated (see descriptions of Laser Induced Fluorescence (LIF)
and X-Ray Fluorescence).
Several
different types of sensors and sampling tools mounted on the SCAPS have
been
tested. The thermal desorption and
Hydrosparge
sensors/samplers are used to detect volatile organic compounds (VOCs)
in soil and groundwater. The thermal desorption sensor/sampler consists
of a
nose cone with a sampling chamber that can be opened to collect a soil
sample.
The sample is heated, volatilizing VOCs. Vapors are transported to
the surface, where
they are analyzed by a portable mass spectrometer. The
Hydrosparge
sensor/sampler inserts a sparge into a groundwater
boring formed by the
cone penetrometer. Using helium gas, it then purges the VOCs from the
water, and
transports them to the surface, where they are also analyzed by a
portable mass
spectrometer.
Sensors
that detect explosive compounds (trinitrotoluene, Royal Demolition
Explosive,
and High Melting Explosive) and their degradation products in soil and
water
have also been demonstrated. A probe is equipped with a
high-temperature heater
for heating the soil. The probe warms the soil to a high temperature
that is
still below the ignition point of the explosive. The vaporized
explosive
compounds are collected and continuously monitored in the
truckÕs mobile
laboratory.
Limitations
and Concerns
SCAPS
is an on-site characterization tool that can be used to delineate contaminant plumes and provide soil
information. However,
the sensors are field-screening tools that do not totally eliminate the
need
for laboratory analyses.
Some
of the sensors and sampling devices may have difficulty detecting small
concentrations.
Verification
of the Hydrosparge sample is difficult to obtain, as only a small
volume of
water is sampled.
There
are concerns that the thermal desorption sensor/sampler will have
different
efficiencies relative to soil types.
SCAPS
has a limited use as a monitoring tool. A new hole has to be punched
every
quarter because the holes collapse after the penetrometer is withdrawn.
Applicability
This
characterization technique can be used to detect explosive compounds,
VOCs,
petroleum products, and metals. With additional sensors, it is
adaptable to
almost any contaminant type.
Technology
Development Status
The
basic technology (i.e., the truck
mounted cone penetrometer) has been commercial
for some time. Sensors and sampling devices for VOCs, explosive
compounds,
metals, and petroleum are well developed, but new sensors (and
refinements in
existing ones) are still being developed.
Web
Links
http://www.epa.gov/esd/cmb/site/pdf/papers/sb125.pdf
Other
Resources and Demonstrations
See
related Technology Descriptions of the Cone Penetrometer, LIF Sensor, and XRF Analysis.
See
Tri-Service Site Characterization and Analysis Penetrometer
System-SCAPS:
Innovative Environmental Technology from Concept to Commercialization, Jane W.
Adams and
George Robitaille, Army Environmental Center SFIM-AEC-ETT, January 2000.
See
http://www.clu-in.org/download/contaminantfocus/dnapl/Detection_and_Site_Characterization/MIPs_validation_USACE.pdf
for validation of membrane interface with SCAPS.