Multi-Sensor Towed Array
Detection System (MTADS)
Description
Traditional
detection and characterization technologies for unexploded ordnance (i.e.,
bombs and shells, or UXO) involve hand-held magnetometers operated by technicians
who must slowly walk across a survey area. When the detector indicates a
ferrous object, the operator marks the location. Known as the ÒMag and FlagÓ
method, it is time consuming and dangerous, as well as inefficient. Many
ordnance items are often disguised by the presence of extensive ÒclutterÓ on
the land surface. Large and deep ordnance items are often not found because
they are difficult for an operator to ÒvisualizeÓ because large items generate
such large magnetic fields that itÕs sometimes difficult to pinpoint or even
notice them against a background of magnetic disturbances. In 1992 the U.S Army
Corps of Engineers estimated that more than 50 percent of the area at UXO sites
could not be surveyed using the hand-held approach. Also, conventional ÒMag and
FlagÓ produces no certifiable survey product, and quality assurance and quality
control are difficult. The Multi-Sensor Towed Array Detection System (MTADS)
technology is designed to address these issues. It should be noted, however,
that other technologies have been developed to address some of the shortcomings
of the ÒMag and FlagÓ approach.
The
MTADS is a vehicle-towed platform equipped with an array of passive magnetic
and active electromagnetic induction sensors that are used to record digitally
evidence of buried UXO or large metal objects such as drums and storage tanks.
Advanced systems are also equipped with an array of chemical sensors and a
Global Positioning System (GPS) to detect and map the location of buried UXO.
The MTADS enhances the speed of detection typically by a factor of ten compared
with the Mag-and-Flag method. The system can survey 10 to 25 acres per day and
provide data at high density (70,000 to 100,000 measurements per acre). The
electromagnetic induction sensor detects small ferrous and non-ferrous
materials. (Some munitions are made of non-ferrous metals. Most artillery fuses
are non-ferrous and are still hazardous if they have separated from the
projectile. Many very small ferrous items cannot reliably be detected by
magnetometers.)
An
advanced system of MTADS places the platform on a helicopter. This permits the
system to detect and classify targets the size of general-purpose bombs or
large caliber shells over large areas and areas not amenable to vehicular based
surveys. Airborne magnetometry has been used in DoD programs associated with
airborne submarine detection and in the commercial geophysical mining
exploration arena. The effects of platform-induced magnetic noise can be
minimized by the application of aeromagnetic compensation techniques that
account for pitch, roll, and yaw and altitude.
Limitations
and Concerns
Vehicular
towed systems are limited, primarily because of difficult topography and
vegetation. Satellite-positioning technology and alternative navigation systems
under consideration will not increase the potential survey area significantly.
GPS navigation is limited to areas with good sky view, limiting operation in
heavily wooded areas. In areas where GPS reception is not possible, an alternative
location system, such as acoustic or laser navigation, may prove useful. As an
alternative, a one-person portable detector equipped with ultrasonic ranging
may be used when GPS signals are degraded due to vegetation.
No
existing technology for characterizing buried UXO achieves the 100% detection
rate sought by many neighbors of military property containing UXO, though they
approach that for items on or just below the surface.
MTADS
is a characterization technology that may enhance the safety, speed and thoroughness
of environmental clean up. Because conditions vary from site to site, other
munitions characterization technologies, it must be validated for each
deployment.
Data
interpretation is a key to the success or failure of this technology.
Magnetic
and electromagnetic detectors have diminished accuracy in highly magnetic
soils.
Applicability
MTADS
is primarily designed to detect UXO in soils (i.e., up to 25 feet for large
objects and up to 3 feet for small objects). It is also capable of locating
ferrous objects such as buried drums in landfills. The U.S. Department of
Defense (DoD) is responsible for over 15 million acres of weapons ranges in the
United States, and over 1,500 sites may require the cleanup of UXO.
Technology
Development Status
MTADS
using a magnetometer and an electromagnetic induction device has been used
successfully, and it is a commercial technology. However, advances in MTADS,
such as new sensors, are in the field demonstration stage. (The airborne MTADS
platform is also used.)
Web
Links
http://www.sandia.gov/Subsurface/factshts/ert/mta.pdf
http://www.serdp-estcp.org/content/download/5606/77694/file/MM-0531-FR.pdf
http://www.serdp-estcp.org/content/download/5564/77315/file/UX-1010-FR-01.pdf
http://www.serdp-estcp.org/content/download/5570/77363/file/UX-9526-FR-03.pdf
http://www.serdp-estcp.org/content/download/5574/77395/file/UX-9811-FR-01.pdf
Other
Resources and Demonstrations
See
ESTCP UXO Cost and Performance Report, Multi-Sensor Towed Array Detection
System (MTADS),
September, 1999. See http://www.serdp-estcp.org/content/download/4446/66132/file/199526.pdf
See
http://www.serdp-estcp.org/Tools-and-Training/Munitions-Response/Wide-Area-Assessment
for multiple descriptions of airborne assessments using similar sensors.