Site Characterization and Analysis Penetrometer System (SCAPS)
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.
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.
Other Resources and Demonstrations
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.