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 is a direct-push platform which also contains a
number of analytical tools. There are other direct push platforms that
are similar. However, most others do not have the wide array of
analytical tools. 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 truckÍs 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.
See http://www.clu-in.org/characterization/technologies/exp.cfm for a
technical
description of explosives in different media and the use of some
analytical
techniques.
See https://ert2.navfac.navy.mil/printfriendly.aspx?tool=energeticconstituents for the
sampling of
energetic constituents.