Interim Design Assessment for the Pueblo Chemical Agent Destruction Pilot Plant (2005)

General Finding 1. On the basis of the initial design documentation for the Pueblo Chemical Agent Destruction Pilot Plant (PCAPP), along with the results from completed technical risk reduction program (TRRP) studies and tests, as well as presentations on the intermediate design, the committee believes that the PCAPP can effectively and safely destroy the chemical agent and the energetic materials in the chemical munitions at Pueblo Chemical Depot. This assessment must be qualified by the limitations in available information and time constraints under which the committee operated, as described in this report. The committee remains concerned with the ability of the continuous steam treater to process dunnage effectively. The basis for the committee’s assessment can be summarized as follows:

• The hydrolysis of HD (distilled mustard agent) is a mature technology whose chemistry has been extensively studied. The chemical mechanisms and kinetics are well established. The chemistry of the hydrolysis of HT (mustard agent containing mustard-T) has not been as extensively studied to date, but the committee does not foresee any major problems with the hydrolysis of HT mustard.

• Although the hydrolysis of energetic materials through the use of hot caustic solutions is not as mature as mustard agent hydrolysis, testing during the earlier engineering design phase of the Assembled Chemical Weapons Assessment program indicates that the energetic materials at Pueblo Chemical Depot in Colorado can be effectively and safely destroyed by this process.

• The successful biotreatment of agent and energetics hydrolysates has been demonstrated both during the engineering design phase of the Assembled Chemical Weapons Assessment program and in the more recent TRRP activities to confirm that the microorganisms transform the hydrolysates to products that are environmentally acceptable.

• The newly designed systems for disassembling the projectiles and the mortars and for accessing the chemical agent in these munitions are up-to-date approaches that appear to be effective. Both use modern, commercially available robots to handle the munitions. The high-pressure water washout of the munitions bodies removes all of the solids as well as the liquid agent from the munitions bodies, thus reducing the chemical agent load on the metal parts treater (MPT). The projectile/mortar disassembly (PMD) machine has not been tested. However, a trade study has been conducted for the new design to replace the PMD machines used in the baseline (incineration) system.

• Although the MPT is still undergoing developmental testing, it should be capable of decontaminating metal parts to a 5X condition.

• The continuous steam treater (CST) for processing dunnage and wastes and the complexity of the CST offgas treatment system constitute an area of great concern to the committee.

The fabrication and testing of the CST will not be completed until late 2004, when the entire PCAPP design is supposed to be in the final stages. The processing of wood in an oxygenfree atmosphere will lead to charring and to the formation of tars. Only wood, activated carbon, and demilitarization protective ensemble suit materials are planned as feeds during TRRP testing; other wastes to be treated in the CST are not being tested.

General Recommendation 1. Alternative approaches for treating the dunnage at the Pueblo Chemical Agent Destruction Pilot Plant should be considered by the Army, with involvement by the public. One such alternative is to send all uncontaminated dunnage and wastes off-site for disposal. Another is to develop a low-temperature system for the treatment of contaminated dunnage to reduce the contamination to levels acceptable for public release in accordance with new Army standards.

General Finding 2. After reconfiguration of the 4.2-inch mortars and 105-mm projectiles, the propellants, fuzes, and igniters that are not contaminated with agent could be sent for off-site disposal to facilities already equipped to treat energetic materials from conventional munitions. This would greatly reduce the energy and process-chemicals requirements for energetics hydrolysis.

General Recommendation 2. The wastes listed in General Finding 2—reconfigured 4.2-inch mortar and 105-mm projectile propellants, fuzes, and igniters not contaminated with agent—should be sent off-site for disposal. The Army should seek guidance from both the permitting agencies and the public on possible approaches to off-site disposal of all uncontaminated wastes from the Pueblo Chemical Agent Destruction Pilot Plant.

General Finding 3. The unit operations in the Pueblo Chemical Agent Destruction Pilot Plant (PCAPP) design have never been operated as a total, integrated process. As a consequence, and notwithstanding the throughput analysis that has been performed, a prolonged period of systemization will be necessary to resolve integration issues as they arise, even for apparently straightforward unit operations. For example, the lack of resolution at the intermediate design stage on the means for transferring agent and energetics following munitions disassembly presents major challenges to completing the PCAPP design.

General Recommendation 3. Adequate time should be scheduled during the design of the Pueblo Chemical Agent Destruction Pilot Plant for the contractor team, the Bechtel Pueblo team, to address integration issues. Addressing these issues should include a major effort to define a safe, efficacious, and acceptable method for transferring agent and energetics to destruction processes following munitions disassembly. Whatever method is implemented should continue to keep the energetics and agent separated.

General Finding 4. Public participation and involvement in the design of the Pueblo Chemical Agent Destruction Pilot Plant (PCAPP) have been strong—starting with the Assembled Chemical Weapons Assessment Dialogue (called the ACWA Dialogue) and continuing through the Colorado Chemical Demilitarization Citizens Advisory Commission and the working groups, whose participants have included volunteers, local government representatives, stakeholder groups, the Army, and others. Public interest in the design of PCAPP remains high. Although there is substantial agreement on the choice of core technologies (hydrolysis and biotreatment), there is not necessarily agreement on all aspects of the plant design—for example, the continuous steam treater and the metal parts treater designs. Thus, there continue to be opportunities for public involvement in the design.

General Recommendation 4. The Army and its contractor should continue to inform and offer meaningful opportunities to involve the public and state and local government officials in relevant Pueblo Chemical Agent Destruction Pilot Plant design decisions and the technical risk assessment process. Also, the Army and its contractor should encourage public scrutiny and be cautious about taking community consent for granted.