&EPA
United States
Environmental Protection
Agency
EPA/540/MR-95/520
August 1995
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
Demonstration Bulletin
Site Characterization Analysis Penetrometer System (SCAPS) LIF Sensor
U.S. Army, Navy, and Air Force (Tri-Services)
Technological Description: The Tri-Services Site Characteriza-
tion Analysis Penetrometer System (SCAPS) was developed by
the U.S. Army (U.S. Army Corps of Engineers, Waterways Ex-
periment Station [WES] and the Army Environmental Center
[AEC]), Navy (Naval Command, Control and Ocean Surveillance
Center), and the Air Force (Armstrong Laboratory). The SCAPS
program is developing a variety of downhole sensors. This dem-
onstration examined the laser induced fluorescence (LIF) sensor
used for petroleum detection. The U.S. Army holds a patent for
the use of a sapphire window to transmit and return incident laser
light and contaminant induced fluorescence. The LIF system
used in the SCAPS system was modified from a design devel-
oped by the Navy to detect petroleum, oil, and lubricant fluores-
cence in seawater.
A complete cone penetrometer system consists of a truck, hy-
draulic rams and associated controllers, and the cone penetrom-
eter itself (Figure 1). The weight of the truck provides a static
reaction force, typically 20 tons, to advance the cone penetrom-
eter. The hydraulic system, working against the static reaction on
force, advances segments of threaded push rod 1 m long and
3.57 cm in diameter into the ground. The cone penetrometer,
which is mounted on the end of the series of push rods, contains
sensors that continuously log tip stress and sleeve friction. The
data from these sensors is used to map subsurface stratigraphy.
Conductivity or pore pressure sensors can be driven into the
ground simultaneously.
The core of the SCAPS LIF system is the Nitrogen laser used to
induce a fluorescence response in soils. The cone penetrometer
unit is mounted on a specially engineered 20-ton truck designed
with protected work spaces. The SCAPS cone penetrometer
system has been modified to provide automatic grouting of the
penetrometer hole during retraction of the cone penetrometer,
and also decontaminates; the push rods as they are retracted
from the soil. The 20-ton cone penetrometer is capable of push-
ing standard push rods to depths of approximately 50 m. The LIF
sensor is mounted slightly above the cone penetrometer sensor.
i
The main LIF sensor components are:
• Nitrogen (N2) laser \
• Fiber optic cable ;
• Monochromator to resolve the fluorescence emission as a
function of wavelength
• Photodiode array (PDA) to detect the fluorescence emission
spectrum and transduce the optical signal into an electrical
signal
• OMA to interface between the optic system and the'computer
system
• Computer system
I
To operate the SCAPS LIF sensor, the cone penetrometer is
positioned over a designated penetration point. The LIF sensor
response is checked using a standard rhodamine solution held
Figure 1. Truck mounted cone penetrometer with SCAPS LIF sensor.
Printed on Recycled Paper
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against the sapphire window; sensor response is checked before
and after each penetration. The cone penetrometer is then ad-
vanced into the soil.
The SCAPS LIF system is operated with a N2 laser. The PDA
accumulates the fluorescence emission response over 10 laser
shots, and the PDA retrieves an emission spectrum of the soil
fluorescence and returns this information to the OMA and com-
puter system. The LIF sensor and stratigraphy data collection are
interpreted and plotted against depth by the onboard computer
system.
The vertical resolution of the SCAPS LIF system is 2 cm. The
fluorescence intensity at peak emission wavelength for each
stored spectrum is displayed along with the soil classification
data. This intensity data can be used to identify waste types.
Waste Applicability: The Tri-Services SCAPS was designed to
qualitatively identify classes and relative concentrations of petro-
leum, polynuclear aromatic hydrocarbons, and some volatile or-
ganic compound contamination in subsurface soil samples.
Demonstration Results: The technology field demonstration
was held in EPA Region 7 during September 1994. An Innova-
tive Technology Evaluation Report (ITER) describing the com-
plete demonstration will be available in late 1995.
Acknowledgment: This Bulletin was prepared by the U.S. Envi-
ronmental Protection Agency, Office of Research and Develop-
ment, National Risk Management Research Laboratory, Cincinnati,
OH 45268.
For Further Information:
EPA Project Manager
J. Lary Jack
U.S. EPA
944 East Harmon
P.O. Box 93478
Las Vegas, NV 89193-3478
702-798-2373
Fax:702-798-3146
United States
Environmental Protection Agency
National Risk Management Research Laboratory (G-72)
Cincinnati, OH 45268
Official Business
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EPA/540/MR-95/520
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