Quality Control Methodologies for Advanced EMI Sensor Data Acquisition and Anomaly Classification

Ryan Steigerwalt P.G. | Weston Solutions, Inc.

MR-201231

Objectives of the Demonstration

Weston Solutions, Inc. performed two Environmental Security Technology Certification Program (ESTCP) Live Site Demonstrations of advanced geophysical classification (AGC) technologies at Southwestern Proving Ground (SWPG), Arkansas, and Andersen Air Force Base (AFB), Guam.

The demonstrations were designed to validate the effectiveness of the advanced sensors and classification methodology at these sites containing a diversity of munitions, densities, and physical challenges.

The primary objectives of each individual Live Site Demonstration were to do the following:

  • Correctly classify all targets of interest (TOIs).
  • Correctly identify TOI and non-TOI sizes.
  • Correctly estimate extrinsic parameters (measured location and depths of items).
  • Reduce clutter digs by at least 50%.
  • Extract reliable parameters for at least 95% of cued anomalies.
  • Demonstrate the cost benefit and performance of these sensors and methods.

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Technology Description

The Geometrics MetalMapper is the first commercially available advanced EMI sensor designed to enable classification of TOI. It consists of three orthogonal 1-square-meter (m²) transmit coils and seven 10-centimeter (cm), three-component, orthogonal receiver coils. The system was proven at the ESTCP Live Site Demonstrations at the former Camp San Luis Obispo and other live sites to be effective at discriminating between munitions and nonmunitions items. Weston operated the MetalMapper in both dynamic detection and cued interrogation modes during the Live Site Demonstration at SWPG. The MetalMapper provides more accurate target positioning advantages over currently used technologies (e.g., EM61- MK2) because of its seven three-component receivers, greater data density, and improved positioning electronics.

The TEMTADS 2x2 is an adaptation of the Naval Research Lab’s standard TEMTADS 5x5 element sensor configuration using a smaller 2x2 element array. The TEMTADS 2x2 consists of four 35-cm transmit coils with four 8-cm tri-axial receiver cubes. The receiver cubes are similar in design to those used in the second-generation Advanced Ordnance Locator and the Geometrics MetalMapper system with dimensions of 8 cm rather than 10 cm. It is as reliable as the original TEMTADS, but its portability and smaller size enables access to difficult terrain where mobility is limited. The center-to-center distance between the transmit coils is 40 cm, yielding an 80 cm x 80 cm array. The array is deployed on a set of wheels resulting in a sensor height of approximately 18 cm.

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Demonstration Results

SWPG: Weston conducted the field demonstration in three phases with 4–6 weeks between each phase to perform data processing and classification. The initial phase included site setup, surface sweep, production area seeding, and dynamic data collection of the survey area. A total of 43 seeds were installed, and 11.23 acres of dynamic surveys were performed with the MetalMapper system. A total of 2,116 targets were selected from the dynamic data for cued investigation, which was performed during the second phase. Weston returned to SWPG for the final intrusive phase, during which 1,398 targets were intrusively investigated. The classification methodology resulted in the correct classification of 100% of TOI, and yielded a reduction in clutter digs of 83%.

Andersen AFB: The demonstration was integrated with an ongoing munitions and explosives of concern (MEC) removal action project being performed in advance of military construction (MILCON) activities. Dynamic detection surveys using TEMTADS 2x2 were performed across 2.97 acres of the site following a traditional EM61-MK2 Metal Detector survey. A total of 970 targets were selected from the TEMTADS 2x2 dynamic survey data. An additional 225 targets were selected from EM61-MK2 data that did not overlap with the TEMTADS 2x2 survey. Each of the 1,195 anomalies were reacquired and interrogated using cued data collection with the TEMTADS 2x2. All TOI were correctly identified during the demonstration. The classification process resulted in correctly identifying 100% of TOI and reduced the number of clutter or nonmunitions- related material that would require investigation by 81%.

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Implementation Issues

Weston Solutions, Inc. conducted several Live Site Demonstrations using advanced electromagnetic induction sensors and data processing techniques to detect and correctly classify buried munitions and explosives of concern (MEC) from nonhazardous items. The demonstrations occurred at former and current military installations to include Spring Valley Formerly Used Defense Site (FUDS), Washington, DC; Andersen Air Force Base, Guam; and Southwestern Proving Ground FUDS, Arkansas. 

At Spring Valley, the Man-Portable Vector (MPV) sensor exhibited implementation and target of interest (TOI) detection advantages in a residential/urban setting. Results from this demonstration show that advanced geophysical classification (AGC) technologies are capable of meeting established remedial action objectives and are now considered an effective methodology for future remedial actions at the FUDS. 
Due to the military history of Guam and the potential presence of military munitions, a MEC removal action is often required in advance of Military Construction (MILCON) activities. A TEMTADS 2x2 demonstration was integrated with an ongoing MILCON project being performed at Andersen AFB to highlight the benefits and considerations for incorporation of AGC technologies with future MILCON work. 

The MetalMapper demonstration at Southwestern Proving Ground provides a full life cycle perspective of incorporating AGC into MEC removal actions. As part of this demonstration a surface clearance, site-wide quality control seeding program, full coverage dynamic surveys, cued surveys, intrusive investigations and explosive demolition operations were completed to fully evaluate the performance and cost of an AGC-centric approach compared to traditional processes used for MEC removal actions. 

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Points of Contact

Principal Investigator

Mr. Ryan Steigerwalt P.G.

Weston Solutions, Inc.

Phone: 267-258-2672

Program Manager

Munitions Response

SERDP and ESTCP

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