Review of International Technologies for Destruction of Recovered Chemical Warfare Materiel (2006)

The scope of work for the committee’s study did not include a review of nontreatment technologies that might be associated with remote detection and accessing buried CWM. However, the U.S. Army requested the committee to compile any relevant technical and legal issues related to the need to detect, assess, access, and remediate the contents of large burial sites that were discovered while researching international destruction technologies.¹ This chapter briefly reviews these issues to provide some further background on technology considerations pertaining to large burial sites.

Large burial sites have not been thoroughly characterized, and their exact contents remain unknown. These sites may contain chemical ordnance of mixed types, fills, and condition, and miscellaneous debris including, in some cases, vehicles and other debris that were used at the sites for decontamination training. The chemical ordnance may be extremely deteriorated, especially in cases where the CWM was burned prior to burial.²

This scenario presents technical challenges for both assessing and accessing the CWM in these large burial sites.

DOD is a leader in the research and practice of detecting subsurface munitions and explosives of concern using geophysical processes. Since the mid-1980s there have been numerous investigative and remediation projects for conventional (high explosive) munitions and explosives of concern under various DOD programs such as the base realignment and closure program and the formerly used defense sites program.

Since that time, geophysical techniques and technologies for the detection of subsurface munitions and explosives of concern have been developed. It is now possible to detect with some accuracy individual or mass buried munitions and explosives of concern; magnetometry and active geophysical systems are the most common and productive technologies (ITRC, 2004).

In addition, DOD has programs supporting research and development in this technical area. Both the Environmental Security Technology Certification Program³ and the Strategic Environmental Research Development Program⁴ support research designed to improve this capability.

However, the technical challenges associated with assessing the contents of the identified large burial sites have not been specifically addressed. These technical challenges are caused by the intermingling of large buried masses of CWM with debris, which presents a complex geophysical signature. Although buried metal and metal masses are commonly detected using geophysical sensors, it is currently not possible to determine if a filled chemical munition is buried within a mass of metal debris using geophysical sensors. It is also not likely that this capability will be acquired in the near future,⁵ and the committee’s research into foreign technology did not reveal any potential breakthroughs in this area using geophysical sensors.

There are, however, some sensing technologies that should be investigated further. One is the use of chemical agent detector dogs to locate subsurface buried CWM. The committee was not able to review any literature in this area because all of the research was classified. However, it is

known that the U.S. Bureau of Customs and Border Protection is using chemical detector dogs to detect CWM. The committee was informed that, although the research done to support this and other similar programs is classified, the chemical detector dogs have been demonstrated to have a detection capability “three to five orders of magnitude greater than the current best instrument detection capability.”⁶ The committee also found that England has plans to conduct tests at the Porton Down facility to determine the effectiveness of chemical agent detector dogs.⁷

If chemical agent detector dogs are demonstrated to be able to reliably detect CWM at very low concentrations, this capability could be applied to assessing large CWM burial sites. For example, it is to be expected that some of the sites, or portions of some of the sites, are free of chemical agent because no CWM was buried in that section of the burial or only empty CWM containers were buried there.⁸ If chemical detector dogs could reliably confirm the absence of CWM, the excavation and removal of objects from portions of the burial pits so identified could possibly be carried out with reduced personal protective equipment and without other precautions normally taken for CWM excavation (negative pressure enclosures, for example).

There are also some potentially useful agent-sensing technologies that do not rely on biological sensors. These new devices may offer more rapid analysis and simpler, continuous measurement. One kind of new sensor is the electronic (or artificial) nose. An array of semiselective, cross-reactive sensors produces a response pattern characteristic of a chemical (Gardner and Bartlett, 1999; Albert and Walt, 2000). The patterns are preprogrammed mathematically so that upon exposure, the patterns are matched to the chemicals sensed. There are two main groups of electronic noses:

• Conducting sensor films and

• Optical sensor arrays.

The conducting sensor films are essentially thin films of materials that swell when exposed, causing resistance changes uniquely characteristic of a particular chemical. Since the process is reversible, these films can be used repeatedly. Their sensitivity has been demonstrated to be in the mid-ppb range for dimethyl methyl phosphonate and diisopropyl methyl phosphonate in air or exhaust fumes (Hopkins and Lewis, 2001).

The optical sensor arrays consist of etched optical fibers with attached dyes that change fluorescence depending on chemical polarity. The sensor’s change in temporal fluorescence at a specific wavelength is monitored and matched to already determined patterns characteristic of known compounds. All of these arrays, electrical or optical, degrade with use.

Some of the new materials being developed that show promise for monitoring chemical agents include fluorescent indicator detectors, surface-enhanced Raman biosensing, and porous silicon technologies. A fluorescent indicator selective for electrophilic phosphates has been developed (Zhang and Swager, 2003). The use of structured nanoparticles coupled to surface-enhanced Raman-based biosensing makes it possible to reduce the size of a sensing unit substantially (Yonzon et al., 2004; Shafer-Peltier et al., 2003).

Based on the optical thickness of films on porous silicon, this new generation of sensors relies on changes in the film to detect chemicals. In tests for volatile organic compounds, polycyclic aromatic hydrocarbons, explosives, and other chemicals, these sensors have been sensitive to ppb ranges (Sailor, 1997).

Lab-on-a-chip technology is advancing rapidly because it has so many potential applications, is small enough for field use, and fast. There are several microchip protocols for monitoring chemical agents and their degradation products, including a precolumn enzymatic reaction, a capillary electrophoresis/conductivity microfluidic device, and a capillary electrophoresis microchip separation and amperometric detection device (Wang et al., 2002, 2004a, 2004b). None of these technologies has been tested extensively enough to allow recommending their use, but they do have the potential to improve current agent-sensing capabilities due to their small size, low power requirements, lower cost, and increased speed.

However, the only reliable method of identifying the contents of a mixed CWM and debris-filled burial pit using currently available known technologies, or technologies likely to be available within the next 5 to 10 years, is archeological excavation—that is, carefully excavating the overburden and accessing the contents for visual identification and nondestructive testing. This nothwithstanding, there appear to be significant possibilities for technology transfer. It may be cost-effective for DOD (including the U.S. Army) to coordinate with other U.S. government agencies to evaluate results from ongoing research programs.

Finding 7-1a. A critical factor in ensuring buried CWM are adequately addressed is developing cost-effective, reliable methods of detecting the presence of buried CWM remotely.

Finding 7-1b. Several U.S. government agencies are investigating remote sensing techniques to detect chemical agents, non-CWM munitions, and buried hazardous waste. Some of this research may be applicable to detecting and assessing buried CWM.

Recommendation 7-1. The U.S. Army should coordinate with other federal agencies on developing an easy-to-use, comprehensive database and on the evaluation of remote techniques to detect buried CWM in a reliable but cost-effective manner.

The committee’s research into foreign technologies showed that almost all foreign countries use a low-tech approach—manual excavation—to accessing buried CWM.⁹ One exception to this is Japan, which is currently planning a combination telerobotic and automated CWM excavation and handling system for the large burial site at Haerbaling, Jinlin Province, China, to dispose of chemical weapons abandoned by the Japanese. This site consists of two very large burial pits expected to contain between 300,000 and 400,000 individual chemical munitions.

For this project, the Japanese are designing a remotely operated and automated excavation system consisting of excavation robots, a device to remove attached soil using pressurized air, and an automated transportation system that will take the removed CWM through a series of cleaning and assessment stations and then finally to a packing station and temporary storage.¹⁰

Although it is not possible for the committee to evaluate a system that has not yet been designed, the concept of automated or telerobotic excavation and handling of CWM deserves to be evaluated.

It is acknowledged that use of robotic systems for excavation and handling of CWM is likely to result in less delicate handling of the CWM than is possible using trained hazardous materials technicians to perform these tasks. This can be seen in the Japanese design for the Haerbaling system, which assumes the unplanned detonation of one out of every 1,000 CWM handled.¹¹ This risk may be unavoidable due to the deteriorated condition of the explosively configured munitions. Furthermore, it may be acceptable if the system is designed to handle the unplanned detonations without serious equipment damage or the release of chemical agent.

What is instructive about the planning of this system is that it demonstrates the trade-offs between preventing unplanned detonations and surviving unplanned detonations, which should be evaluated before deciding on the approach that will be used to excavate and handle CWM at the large U.S. burial sites. The trade-offs include these:

• Using trained technicians to manually remove and handle the CWM is likely to result in more delicate handling of the CWM and fewer unplanned detonations. However, an unplanned detonation in this scenario is likely to have catastrophic and unacceptable consequences (severe injury or death of the technicians).

• Using telerobotic or automated robotics to perform the excavation, removal, and handling of CWM will result in rougher handling and more unplanned detonations. However, adequate engineering of the system will result in less serious consequences for each unplanned detonation.

The current technology for robotics is mature, and a significant amount of research and development is being done by private companies to support advances in manufacturing processes.¹² Much of this technology is applicable to the development of robotic systems for use on large CWM burial sites.¹³

As a result, the best solution to accessing CWM in large burial sites may be a combination of manual removal using trained technicians and, when the risk is unacceptable, removal by a suite of mobile robotic systems specially developed to perform specific high-hazard tasks as needed.

The likelihood that large CWM will be found in a deteriorated condition means that the Non-Stockpile Chemical Materiel Project (NSCMP) must be able to treat large CWM in place without unnecessary movement. This is true for burial sites containing large numbers of CWM as well as for sites containing few or even single items. Research by the committee into foreign solutions to this problem indicates that no new foreign technology has been developed or is likely to be developed that is useful to NSCMP.

Most other countries respond to this scenario by open detonation of the unstable CWM using at least 5 pounds of explosive for each pound of chemical agent.¹⁴ In this situation, it is hoped that the high detonation temperature of the donor explosive will consume a large portion of the chemical fill. Some countries employ considerably larger amounts of explosive in an attempt to maximize the destruction of the agent fill. However, such a solution is considered by the

committee to be generally unacceptable in the United States owing to the difficulty of obtaining regulatory approval for this method of disposal.

The committee’s research has shown that the NSCMP is a leader in developing technology to address this scenario. The NSCMP has already developed the system requirements for the Large Item Transportable Access and Neutralization System (LITANS) and is currently developing the system (U.S. Army, 2005).

The requirements call for a system that can house and contain a CWM up to a ton container in size. Moreover, the system will be portable and allow for drilling, sampling, agent removal, and neutralization while preventing releases of agent during processing.

The NSCMP is also currently using the Monica remote case entry and sampling system manufactured by MMIC EOD of England.¹⁵ This is a commercially available remote annular drill and seal system with a vacuum mounting system. According to the NSCMP, this system has been determined to be useful for accessing and removing agent fills from large CWM. However, some leakage has occurred, which prevents use of this system without vapor containment.¹⁶ This requirement notwithstanding, according to the NSCMP, it is likely that the Monica remote case entry and sampling system will be an acceptable solution to accessing the agent in large CWM as long is it is used within a containment structure such as LITANS.

All of the above systems, however, require that the CWM be moved at least a small distance into the LITANS enclosure. This may not be acceptable in the case of an extremely deteriorated or possibly shock-sensitive CWM that has been determined to be unsafe to move. In this case an alternate containment system that can be installed over the CWM at its existing location is needed.

One potential solution to dealing with extremely deteriorated or shock-sensitive CWM has been investigated by the NSCMP: the ballistic tent-and-foam system. According to the testing plan for the ballistic tent-and-foam system,

The government of England is currently using a similar double-tent containment system for in-place disposal of CWM by detonation.¹⁷

It is the opinion of the committee that the LITANS/ Monica system is the most promising solution for the disposal of large CWM and ton containers that can be moved into the LITANS containment system. However, there is a need for a system to allow in-place disposal of deteriorated and unstable CWM without moving the munition.

It is possible that a hybrid application of the Monica remote case entry and sampling system and a tent-like containment structure and APC system, similar to the existing ballistic tent used for the tent-and-foam system, can be easily developed, tested, and fielded to fill this need. This new system would use the tent-and-foam and APC technology to contain and capture any chemical agent released during the agent removal via the Monica without requiring the munition to be moved from the location where it was found.

According to PMNSCM, the results of its testing of the tent-and-foam detonation system have not been promising, and the testing of this system has been discontinued.¹⁸ This leaves a gap in the CWM disposal capabilities of PNMSCM because there is currently no method for in-place disposal of small CWM by detonation that is acceptable to most environmental regulators.

Albert, K.J., and D.R. Walt. 2000. High-speed fluorescence detection of explosive-like vapors. Analytical Chemistry 72(9): 1947-1955.

Gardner, J.W., and P.N. Bartlett. 1999. Electronic Noses: Principles and Applications. Oxford, England: Oxford University Press.

Hopkins, A.R., and N.S. Lewis. 2001. Detection and classification characteristics of arrays of carbon black/organic polymer composite chemiresistive vapor detectors for the nerve agent stimulant dimethylmethylphosphonate and diisopropylmethylphosponate. Analytical Chemistry 73(5): 884-892.

ITRC (Interstate Technology Regulatory Council). 2004. Geophysical Prove-Outs for Munitions Response Projects, November. Washington, D.C.: Interstate Technology Regulatory Council Unexploded Ordnance Team.

Sailor, M.J. 1997. Sensor applications of porous silicon. Pp. 364-370 in Properties of Porous Silicon. L. Canham, ed. Exeter, England: Short Run Press Ltd.

Shafer-Peltier, K.E., C.L. Haynes, M.R. Glucksberg, and R.P. Van Duyne. 2003. Toward a glucose biosensor based on surface-enhanced Raman scattering. Journal of the American Chemical Society 125(2): 588-593.

U.S. Army. 2005. System Requirements Document for the Large Item Transportable Access and Neutralization System, October. Aberdeen Proving Ground, Md.: Program Manager for the Elimination of Chemical Weapons.

U.S. Army. Undated. Environmental Assessment for Ballistics Testing of Tent and Foam for Use in Removal Actions at Aberdeen Proving Ground, Maryland. Available online at <http://www.apg.army.mil/apghome/sites/directorates/restor/environmental_assessment.htm>. Last accessed May 3, 2006.

Wang, J., M. Pumera, G.E. Collins, and A. Mulchandani. 2002. Measurements of chemical warfare agent degradation products using an electrophoresis microchip with contactless conductivity detector. Analytical Chemistry 74(23): 6121-6125.

Wang, J., G. Chen, A. Muck, Jr., M.P. Chatrathi, A. Mulchandani, and W. Chen. 2004a. Microchip enzymatic assay of organophosphate nerve agents. Analytica Chimica Acta 505(2): 183-187.

Wang, J., J. Zima, N.S. Lawrence, M.P. Chatrathi, A. Mulchandani, and G.E. Collins. 2004b. Microchip capillary electrophoresis with electrochemical detection of thiol-containing degradation products of V-type nerve agents. Analytical Chemistry 76(16): 4721-4726.

Yonzon, C.R., C.L. Haynes, X. Zhang, J.T. Walsh, Jr., and R.P. Van Duyne. 2004. A glucose biosensor based on surface-enhanced Raman scattering: Improved partition layer, temporal stability, reversibility, and resistance to serum protein interference. Analytical Chemistry 76(1): 78-85.

Zhang, S.W., and T.M. Swager. 2003. Fluorescent detection of chemical warfare agents: Functional group specific ratiometric chemosensors. Journal of the American Chemical Society 125(12): 3420-3421.

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