Disposal of Neutralent Wastes: Review and Evaluation of the Army Non-Stockpile Chemical Materiel Disposal Program (2001)

Chemical warfare materiel (CWM) is a collection of diverse items that were used during 60 years of efforts by the United States to develop a capability for conducting chemical warfare. Nonstockpile CWM, which is not included in the current U.S. inventory of chemical munitions, includes buried materiel, recovered materiel, binary chemical weapons, former production facilities, and miscellaneous materiel. CWM that was buried in pits on former military sites is now being dug up as the land is being developed for other purposes. Other CWM is on or near the surface at former test and firing ranges. According to the Chemical Weapons Convention (CWC), which was ratified by the United States in April 1997, nonstockpile CWM items in storage at the time of ratification must be destroyed by 2007. ¹

The U.S. Army is the designated executive agent for destroying CWM. Nonstockpile CWM is being handled by the Non-Stockpile Chemical Materiel Program (NSCMP); stockpile CWM is the responsibility of the Chemical Stockpile Disposal Program. ² Because nonstockpile CWM is stored or buried in many locations, the Army is developing transportable disposal systems that can be moved from site to site as needed. The Army has plans to test prototypes of three transportable systems—the rapid response system (RRS), the munitions management device (MMD), and the explosive destruction system (EDS)—for accessing and destroying a range of nonstockpile chemical agents and militarized industrial chemicals. The RRS is designed to treat recovered chemical agent identification sets (CAIS), which contain small amounts of chemical agents and a variety of highly toxic industrial chemicals. The MMD is designed to treat nonexplosively configured chemical munitions (i.e., munitions containing chemical agents but no fuzes, propellants, or burster charges). The EDS is designed to treat munitions containing chemical agents with energetics equivalent to three pounds of TNT or less. These munitions are considered too unstable to be transported or stored. A prototype EDS system has recently been tested in England by non-stockpile program personnel. Although originally proposed for evaluation in this report, no test data were available to the committee on the composition of wastes from the EDS. Therefore, alternative technologies for the destruction of EDS wastes will be discussed in a supplemental report in fall 2001. Treatment of solid wastes, such as metal munition bodies, packing materials, and carbon air filters, were excluded from this report.

Because of differences in the solvents and chemical agents in CAIS materials and recovered chemical munitions, the RRS and MMD use different neutralization chemistries and produce different liquid waste streams —collectively referred\ to in this study as “neutralent wastes” or “neutralents.” A summary of nonstockpile CWM that will be treated by the RRS and MMD, as well as the major constituents of their neutralent waste streams, is given in Table ES-1. According to the Army, the maximum permissible concentration for blister agents in a neutralent stream is 50 parts per million (ppm) (although in practice the actual concentration is more likely to be about 1 ppm). The maximum for nerve agents is 20 to 30 parts per billion (ppb). RRS neutralents may contain arsenic, a toxic heavy metal that must be captured and immobilized.

Because neutralent wastes from the RRS and MMD are expected to be classified as hazardous wastes under the

Resource Conservation and Recovery Act (RCRA),³ the Army's current plan is to send them to a permitted hazardous waste incinerator for final disposal. However, the incineration of chemical agents elsewhere has aroused considerable opposition among some public interest groups, and this opposition may be extended to the incineration of RRS and MMD neutralents (even though the concentration of agent in the neutralents will range from ppb to a few ppm). In anticipation of increasing public opposition, the Army is investigating alternative (nonincineration) technologies for disposing of neutralents and has asked the National Research Council for advice. This report is a result of that request.

The following Statement of Task was given to the National Research Council by the Army: ⁴

Evaluate the near-term (1999–2005) application of advanced (nonincineration) technologies, such as from the Army's Assembled Chemical Weapons Assessment Program and the Alternative Technologies and Approaches Project, in a semi-fixed, skid-mounted mode to process Rapid Response System, Munitions Management Device, and Explosive Destruction System liquid neutralization wastes.

Around the time the committee was conducting this study, the Army asked two other contractors to undertake similar, though not identical, studies. Mitretek was asked to evaluate the applicability of six technologies being investigated by the Assembled Chemical Weapons Assessment (ACWA) Program (part of the stockpile CWM). Stone & Webster was asked to publish a Commerce Business Daily announcement requesting proposals for alternative technologies for the destruction of neutralents and to evaluate the proposals received. The committee received briefings on these projects and took account of them in its deliberations.

The committee began by establishing some boundaries for the study. As required by the Statement of Task, only liquid neutralent wastes from the RRS and MMD were considered. First, EDS neutralents were omitted because the-liquid neutralent (at the time this report was developed) had not been well characterized. Second, the end point of the neutralent treatment technology was taken to be solids that could be disposed of in a permitted landfill and liquids that could be released to a federally owned or publicly owned treatment works. Third, the air discharges would contain only CO₂, water vapor, and nitrogen. Therefore, setting discharge parameters would not be necessary.

The committee's approach to identifying technologies with the greatest potential for the timely, cost-effective treatment of RRS and MMD neutralents consistent with the protection of human health and the environment had two aspects. Clearly, legacy equipment developed by the ACWA Program and mature commercial destruction technologies that have the potential to destroy RRS and MMD neutralent, do not involve incineration, and require little or no development investment should be considered first. The committee recognizes that the Army is not starting its selection process with a blank slate. Several alternative technologies have

already been initially evaluated as part of the ACWA Program and in commercial projects for treating hazardous wastes. If RRS and MMD neutralents could be effectively destroyed by “piggybacking” on ACWA or mature, commercial destruction technologies, (e.g., wet-air/O₂ oxidation [WAO], chemical oxidation, or PLASMOX^®5 as used today for waste disposal purposes) this might provide a relatively inexpensive and expedient course of action.

In the event that none of the existing ACWA legacy equipment or commonly used commercial technologies in their present form and state of development prove to be acceptable, the committee assembled a list of alternative treatment technologies that might, with development and investment, meet the needs of the NSCMP. These technologies became the focus of the committee's investigations and analyses. Eight candidate technologies were evaluated based on the collective judgment of the committee that the technology is likely to be safe, effective, and permitted, as well as consistent with pollution prevention principles. These eight technologies were ranked in order of preference:

1. chemical oxidation

2. wet-air/O₂ oxidation (WAO)

3. electrochemical oxidation with silver Ag(II) and cesium Ce(IV)

4. supercritical-water oxidation (SCWO)

5. solvated-electron technology (SET)

6. gas-phase chemical reduction (GPCR)

7. plasma-arc technology

8. biodegradation

Because the neutralents of the RRS and the MMD are very different chemically, the committee assessed the appropriateness of each technology for each type of neutralent separately. The ability of a given technology to destroy both types of neutralent effectively was considered a plus, but no technology was rejected if it would be effective for only one neutralent stream.

The committee's criteria were based on best practices in the chemical industry, including a criterion based on pollution prevention (e.g., minimizing the volume of material that must be added at the front end of the process and minimizing the production of high-temperature vapor streams at the back end of the process). The committee divided the best practices into two categories: top priority criteria and important criteria. The top priority criteria are:

• inherent safety

• technical effectiveness

• pollution prevention

• permit status

The important criteria are:

• robustness

• cost

• practical operability

• continuity

• space efficiency

• materials efficiency

Unlike the Mitretek and Stone and Webster studies mentioned above, the committee made no attempt to assign quantitative weights to the criteria. Instead, the technologies were evaluated qualitatively. Because the Army had no information on actual tests of the destruction of real or simulated nonstockpile neutralents, the committee relied on the expert judgment of committee members to evaluate each process and to suggest the most promising technologies for development.

Although the committee's primary objective was to evaluate alternative treatment technologies for neutralent waste streams, the committee also took into account public and regulatory acceptability, which are likely to affect the selection of alternative technologies. Some public interest groups opposed to incineration who have been actively involved in the policy debate were invited to attend committee meetings. As often as feasible, committee members met with public interest groups and quasigovernmental citizen committees to solicit their views, which were also considered in the committee's evaluations. In addition, the committee incorporated information from discussions with the Environmental Protection Agency (EPA) on potential regulatory approaches for expediting the implementation of alternative technologies for treating neutralent waste.

Finding. The committee did not find any experimental studies on the destruction of neutralent wastes generated by the RRS or MMD. Therefore, the analyses of candidate technologies are based on their demonstrated performance with chemically similar materials, as well as on fundamental principles of chemistry and chemical engineering.

Finding. Based on the amount of neutralent expected from planned operations at Deseret Chemical Depot and Dugway Proving Ground, the volume of neutralents generated by the RRS and MMD is expected to be relatively small—on the

order of 5,000 gallons per year in normal operation. As a point of reference, a standard tanker truck contains 5,000 to 10,000 gallons, and a railcar may contain as much as 30,000 gallons. Because the facility for disposing of neutralent will not have to handle large volumes or have a high throughput, it could be a laboratory or pilot-plant scale facility. Thus equipment for technologies currently under investigation for stockpile CWM might be used cost effectively for treating nonstockpile neutralents. At this small scale, all of the technologies reviewed by the committee could be adapted to “semi-fixed, skid-mounted” configurations (see Statement of Task).

Finding. The committee identified some low-temperature, low-pressure, less complex technologies that might be used to treat neutralent waste. The benefits of these technologies over incineration include low worker risk, public acceptance, low risk to the surrounding community, and simplicity of operation.

Finding. The Army's evaluation of alternative technologies must meet the time constraints of the CWC, which requires that all nonstockpile CWM in storage at the time the convention was ratified be destroyed by 2007. Thus far, no alternative incineration technologies have been tested on real, or even simulated, nonstockpile neutralent generated by either the RRS or the MMD. Therefore, bench testing and scale-up demonstrations of candidate technologies with neutralents will be necessary. Because testing the effectiveness of alternatives and determining regulatory limits will take time, the Army may have to fall back on its current incineration strategy for the destruction of neutralent, which includes the use of commercial incinerators, or even the use of the Army' s stockpile incinerators.

Finding. Some of the candidate alternatives to incineration for destroying MMD and RRS neutralents involve hardware that has already been developed, and using them would simply require substituting neutralent for existing feeds. For example, one or more of the demonstration units tested for the chemical disposal programs (e.g., ACWA Program) might be used. Because the volume of nonstockpile neutralents will be small, even if the technology is not rated highly according to the committee 's criteria but is inherently safe, the savings in time and development costs might justify consideration of this alternative. Demonstration units could be used at their present sites or moved, either as needed or to a mutually agreeable location based on a plan developed with the affected communities and regulatory authorities.

Recommendation. The Non-Stockpile Chemical Materiel Program should pursue a two-track strategy similar to the one adopted by the committee during its selection of a technology: (1) an evaluation of the potential of Assembled Chemical Weapons Assessment demonstration technologies and mature commercial technologies; and (2) technologies that would require further development and investment.

Recommendation. As part of the track-one strategy, the Army should take advantage of available equipment that would require little or no investment (i.e., either alternative technologies from the Assembled Chemical Weapons Assessment [ACWA] Program or existing commercial technologies, such as chemical oxidation, wet-air/O₂ oxidation, or PLASMOX^®). The following technologies from the ACWA demonstrations should be considered: electro-chemical oxidation Ag(II), gas-phase chemical reduction, solvated-electron technology, and supercritical water oxidation. If any of these can accomplish the task safely, it might provide a relatively rapid and inexpensive course of action.

Recommendation. If Assembled Chemical Weapons Assessment (ACWA) or the commercial technologies require substantial modifications to processes or permits, the Army should focus first on the most easily adaptable commercial technologies (i.e., chemical oxidation and wet-air/O₂ oxidation). Only if these technologies prove to be unsuitable should the Army consider investing resources in the further development of ACWA technologies (listed below in order of preference):

• electrochemical oxidation with Ag(II) and Ce(IV) ⁶

• supercritical water oxidation

• solvated-electron technology

• gas-phase chemical reduction

• plasma-arc technology

Recommendation. The Army should not invest in further development of biodegradation, which was judged least likely to be effective.

Recent experience by federal agencies has shown that the involvement of diverse public groups (including state and federal regulators) is crucial to timely decision making. Stakeholder involvement is particularly important for decisions involving analytical, engineering, or other scientific uncertainties about the protection of human health and the environment. The Army's implementation of an alternative technology or technologies to incineration could be delayed unless regulatory requirements have been developed and the public has been involved in the decision-making and selection process.

The NSCMP could improve its existing public involvement program by (1) exploring ways to ensure representation

of diverse public groups in assessments of disposal technologiesand associated regulatory issues; and (2) by working closely with potential host communities to identify and address their concerns.

A comprehensive regulatory compliance plan that involves all stakeholders could be essential to the timely implementation of an alternative technology. An environmental criteria working group, with representatives of the Army, the Environmental Protection Agency, state regulators, officials of the U.S. Department Health and Human Services, public interest groups, and citizens at large, could be formed to undertake advanced planning with the goals of (1) ensuring that substantive regulatory requirements can be met and (2) determining if additional testing or evaluations will be necessary to satisfy public or regulatory concerns.

Finding. Citizens groups that met with the committee strongly urged that the Army consider the long-term storage (i.e., longer than one year) of neutralents rather than incineration. Storage, they argued, would ensure that the Army would have sufficient time to develop, test, and obtain regulatory approval of alternatives to incineration. The committee believes that the Army's mission could be affected by the manner in which it responds to these public concerns.

Finding. The Army provided several reasons for not storing neutralent. First, storage might make it impossible to meet the treaty deadlines for the destruction of the nonstockpile chemical weapons. Second, the Army might be required to meet rigorous, long-term environmental requirements. Third, long-term storage would be inconsistent with regulatory requirements limiting storage time for hazardous wastes. Finally, the cost of storage might be disproportionately high.

Recommendation. To solicit public understanding, and perhaps acceptance, in its decision on whether or not to store neutralent, the Army should issue a detailed white paper explaining the legal, scientific, regulatory, and institutional issues involved. The paper should explicitly describe how risk to the public and workers would be affected by the long-term storage of neutralent prior to its disposal.

Finding. The committee's discussions with citizen groups indicated a need for, and the value of, public involvement in the Army's decisions concerning the selection, deployment, and employment of technologies for disposing of non-stockpile chemical materials.

Recommendation. The committee recommends that the Army expand its public involvement program regarding disposal of nonstockpile chemical materiel. Enough time should be scheduled and enough resources allocated to ensure that the decision-making process is open and that members of the public are involved in determining trade-offs related to the selection, siting, deployment, and employment of disposal technologies.