Integrated Design of Alternative Technologies for Bulk-Only Chemical Agent Disposal Facilities (2000)

At both the ABCDF and NECDF, several waste streams will be generated from the treatment processes. Although they differ appreciably because of the differences in the processes, they also have many features in common. An underlying principle in the plant designs for managing these waste streams is that they be treated on site only to the point that they can be safely shipped to outside organizations for final treatment and disposition. On-site final treatment is avoided if possible. Although this approach makes economic sense, it also means that management systems to ensure safe and efficient handling will be necessary. To that end, the Army should take the following steps:

• define criteria for off-site shipment

• validate technologies and measurement techniques for meeting these criteria

• define and install backup on-site systems where warranted

• obtain necessary permits

• obtain public acceptance

• institute operating practices and systems for maintaining safe and efficient handling of wastes, on and off site

At both the ABCDF and NECDF, agent destruction is accomplished during the neutralization process step, the product of which is hydrolysate. Although each hydrolysate contains reaction products that require monitored destruction under the CWC, their characteristics are similar to those of common industrial hazardous wastes. The committee believes that off-site treatment of hydrolysate may offer significant cost and schedule benefits to the CSDP and could at least be considered a contingency plan in case difficulties arise during start-up and pilot testing of the on-site hydrolysate (postneutralization) process steps. Off-site treatment of the hydrolysates will require that suitable treatment and disposal facilities be identified and that public acceptance of this approach be obtained. Identification and public acceptance of off-site treatment and disposal facilities for hydrolysates may be challenging. However, at the Tooele, Utah, facility, aqueous waste streams that do not contain agent are currently being disposed of off site. Thus, the committee believes that it is prudent to maintain both on-site and off-site treatment and disposal options where possible.

Besides process effluent streams, the operation and eventual closure of both the ABCDF and NECDF will produce agent-contaminated wastes. Some examples are listed below:

• demilitarization protective ensemble suits and breathing air hoses used by workers doing maintenance in plant areas subject to agent contamination

• activated carbon and other filter materials used to control emissions

• waste materials (e.g., particles, sludges, and fluids) removed from process lines, filters, and strainers during maintenance operations

• plant equipment operations (e.g., small parts, liners, etc.) removed and replaced during maintenance

• maintenance equipment and supplies (e.g., pails, tools, absorbent spill pillows, wipes)

• primary plant equipment and agent-contaminated surface coatings or layers removed during closure of the facility

A comprehensive list of nonprocess wastes that will require treatment and disposal management can be found in the documentation for closure of the Johnston Atoll facility (U.S. Army, 1999b).

The Army must make provisions for storing, decontaminating, shipping, and disposing of nonprocess waste materials, including the plant itself, which must be treated as waste. In the baseline incineration system, contaminated wastes can be disposed of in the various incinerators. But comprehensive plans will have to be developed for the disposal of all contaminated waste streams at the Aberdeen and Newport facilities. For example, waste might be decontaminated with

the neutralizing medium used to hydrolyze agent and the resulting stream treated in the plant. At the ABCDF, the subsequent treatment would involve removal of VOCs followed by treatment in the SBR; the SCWO system would be used at the NECDF. However, the compatibility of the waste stream with the disposal equipment and operation would have to be investigated. Several waste streams at baseline incineration system facilities—especially plastic hoses, parts, and containers —have been especially difficult to decontaminate.

Operations at both the ABCDF and NECDF will result in a waste stream of used activated carbon from areas that are known to be or could potentially be contaminated with agent. Used activated carbon from process steps and areas where agent is not present (e.g., VOC removal from hydrolysate at the ABCDF) will also have to be disposed of. This carbon is intended to be regenerated and reused. Process monitoring, record keeping, and segregation will be necessary to differentiate the carbon that is or has potentially been exposed to agent from that which has not. Carbon exposed (or potentially exposed) to agent is not being considered for regeneration, whereas unexposed carbon is expected to be regenerated. Activated carbon that has been used to treat exhaust from areas known to be contaminated or areas that could potentially be contaminated with agent will have to be shown to be free of agent to below required levels for shipment off site. Sampling and analytical methods will be necessary to meet this challenge.

For off-site shipment of decontaminated wastes, provisions will have to be made for qualifying the wastes for shipment, as well as arrangements made for receiving and disposing of them. Attempts to ship agent decontamination brines (that were tested to be free of agent) from the Johnston Atoll facility met with extreme public resistance and were eventually disallowed. Off-site shipment of nonprocess wastes from the ABCDF and NECDF may present an even more complex problem because of the diversity of physical waste forms, a known history of agent contact for some wastes, and the Army's inability to demonstrate definitively that the waste stream is truly free of agent. If the traditional headspace analysis used to establish 3X conditions is not sufficient to release materials from Army control,1 non-incineration methods for the complete decontamination of nonprocess wastes and analytical methods for verifying that materials are free of agent will be necessary. Testing of MOCs and performance evaluations will have to be an intrinsic part of the EST program, both for the SCWO reactor and for downstream components exposed to aggressive environments (e.g., pressure and temperature reduction components). The selection and reliability of all primary SCWO components will have to be thoroughly demonstrated by process performance.

Recommendation 4-1. The Army should evaluate off-site management of hydrolysates both for potential cost and schedule benefits and as a contingency plan in case difficulties arise during start-up and pilot testing of the on-site (postneutralization) process steps.

Recommendation 4-2. The Army should define the quantity and characteristics of anticipated nonprocess waste streams and evaluate options for the final disposition of each type of waste. On-site processes should be developed and demonstrated for treating all agent-contaminated wastes. Methods of representative sampling and characterization of wastes should be developed to verify that treated wastes are free of agent to below appropriate risk thresholds.