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Review and Assessment of Developmental Issues Concerning the Metal Parts Treater Design for the Blue Grass Chemical Agent Destruction Pilot Plant 3 Assessment of Metal Parts Treater Testing Activities The metal parts treater (MPT) concept has been subjected to testing by the Bechtel Parsons Blue Grass Team (BPBGT) in Technical Risk Reduction Programs (TRRPs) for the Blue Grass Chemical Agent Destruction Pilot Plant (BGCAPP), with most of the pertinent testing conducted under TRRP 05c. (See Box 3-1.) This testing has used a three-quarter-scale version of the MPT, designated as the TRRP MPT. The testing objectives as given in the Bechtel TRRP 05c test plan were as follows (BPBGT, 2007d): Demonstrate reliable mechanical performance of all parts and functions of the MPT design, including seals, doors, bearings, and projectile jamming. Demonstrate BGCAPP-specific design improvements such as: projectile orientation, steam-injection orientation, gas take-off orientation, and tray design to improve heatup. Calibrate the computational fluid dynamics (CFD) model of the test unit on VX 155-mm projectiles to serve as a basis for first-of-a-kind (FOAK) full-scale unit modeling. Inherent in this objective is the necessary demonstration that the MPT can heat all parts of materials fed to it to 1000°F for at least 15 minutes at a rate that meets expected feed rates during operation. Demonstrate treatment of simulated energetics batch hydrolyzer (EBH) rocket warhead debris. Demonstrate limited secondary-waste treatment options to gather data for further effort with the CFD model. Perform test runs and cycles of components to make observations of critical design parameters that apply to the FOAK unit under design—particularly those that affect the risk of scale-up to the full-scale unit. These include, but are not limited to, projectile paint debris generation and accumulation, thermal expansion stresses and deformation points, interferences, Gaussian field measurements and localized heating effects, and wall temperature distribution. The TRRP MPT testing used an off-gas treatment system that included a catalytic oxidizer (CATOX) unit rather than a bulk oxidizer (BOX) unit that will be used for the full-scale MPT and did not include the venturi scrubber. The CATOX unit had a processing rate of 30 pounds per hour (lb/h) of oxidizable gases. The BOX is being designed to process up to 252 lb/h of oxidizable gases. Thus the flow of off-gas from the MPT enclosures was demonstrated, but not the OTM configuration, the maximum gas flow rates, or equipment that will be provided for the full-scale MPT. The OTM BOX unit is also considered to be a first-of-a-kind system, as mentioned in Chapter 2. TRRP MPT testing was performed using surrogates of all munitions metal parts and waste feed streams anticipated for the two BGCAPP full-scale MPTs except halogenated waste and energetics batch hydrolyzer (EBH) waste containing energetic materials. All feed streams were tested. However, the BPBGT terminated the waste stream testing before the completion of all planned tests because it was felt that sufficient data to design the full-scale MPT had been obtained. This committee has chosen to group the TRRP MPT test results into three areas for review and evaluation. They are (1) mechanical issues, (2) secondary and closure waste issues, and (3) results of thermal testing and thermal modeling. A discussion of results obtained and required future testing for the first two issues follows, and issue 3 is discussed in Chapter 4. MECHANICAL ISSUES The following is a discussion of key mechanical issues identified in the TRRP MPT testing. New Door Closure Mechanism and Seals Difficulties with getting an acceptably tight closure on the air lock and main chamber doors for the TRRP MPT have resulted in a change in the design of the door closure mechanism and seals for the full-scale MPT. Instead of the
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Review and Assessment of Developmental Issues Concerning the Metal Parts Treater Design for the Blue Grass Chemical Agent Destruction Pilot Plant J-type sliding closure mechanism used on the TRRP MPT, the door for the full-scale MPT will be moved against the closure face by using a two-direction cam design recommended by a commercial oven contractor. To close a door, this design moves the door vertically downward with a mechanical screw drive to its bottom position, and the door is then moved horizontally against the closure face. In addition, the seal material design has been altered to give the equivalent of two gaskets between the door and closure face. A prototype of this new arrangement has been developed and tested, but not under the expected operating conditions. Changes were also made in the structural support for the door closure and main chamber to make it easier to get a good seal. It is noted that all of this testing was done with doors for a 4-ft.-8-in.-diameter chamber and that the full-scale MPT will use a 6-ft.-6 in.-diameter main chamber. Finding. The larger size of the full-scale MPT doors will pose additional challenges in maintaining seal face alignment and minimizing air in-leakage during operation. Finding. The new closure mechanisms for the four doors on the full-scale MPT have not been tested at operating conditions. Recommendation 3-1. The new closure mechanisms for the full-scale MPT should be tested and cycled at operating conditions at the fabrication facility prior to systemization. Bearings for the Conveyor Rollers The Graphalloy® bearings for the conveyor rollers in the main chamber experienced galling and other wear failures during TRRP testing.1 The bearing failures were attributed to oxidation/corrosion at the main chamber operating temperature. Three different bearing materials were evaluated: “improved” Graphalloy®, Stellite, and Deva (Deva-Mogul sintered metal). The Stellite and Deva bearings are more expensive than Graphalloy® bearings, and the Deva bearings are produced by a foreign manufacturer. The Stellite bearings exhibited surface galling and friction at temperature, causing the bearings to come loose from their mountings and interfere with the trays. All materials experienced wear. The BPBGT concluded that the “improved” Graphalloy® bearings were acceptable, although they exhibited some pitting. The BPBGT also developed a bearing-mounting design that allows for quick replacement of the bearings. The toncontainer MPT used at the Newport Chemical Destruction Facility, Indiana, has experienced similar bearing failures, and a repair and replacement approach was adopted.2 During full-scale MPT testing, the BPBGT intends to reconsider Stellite bearings that are interchangeable with the Graphalloy® bearings. The BPBGT believes that it has identified an acceptable path forward for resolving the problem of premature main chamber conveyor bearing failures. However, replacing the bearing mounts will require cooling the unit and reheating. Excessive temperature cycling could cause metal fatigue. The BPBGT has also developed maintenance protocols that shorten replacement times for bearings as much as possible. Finding. The proposed conveyor bearing selection and replacement approach is appropriate, but actual demonstration of reliable performance has yet to be achieved. If bearing replacement is required more frequently than anticipated, it could reduce the MPT throughput rate. Recommendation 3-2. The proposed approach for the replacement of conveyor bearings should be tested in conjunction with the testing of the full-scale MPT at operating temperature and design with tray loading at the fabrication facility. Heating Zones The full-scale MPT will use two heating zones in the main chamber. Each will be capable of 450 kW of induction heating. The TRRP MPT used one 600-kW induction heater. It is unclear whether maintenance on one MPT would be possible while the other was in operation. If not, when one MPT required in-room maintenance, it could not be repaired until the second MPT was shut down. It would reduce the availability of the MPTs if both had to be shut down when either required in-room maintenance. Finding. It is unclear that heat and magnetic fields generated by one MPT would allow maintenance on the second unit while the first was in operation. Recommendation 3-3. The BPBGT should consider providing suitable spacing and electromagnetic and thermal shielding to allow maintenance on one unit while the other is operating. TRRP testing and computational fluid dynamics (CFD) modeling showed that certain areas of some projectiles being heated in the main chamber were heating more slowly than most parts of the projectiles. This slower heating required longer heat-up times to achieve the 1000°F for 15 minutes for all projectiles. After its review of the chamber design, the BPBGT concluded that the slow heating resulted from “shadowing” of parts of the projectiles during the radiant heating process. 1 John Ursillo, Pasco Resident Engineer, Bechtel Parsons Blue Grass Team, “MPT Technical Risk Reduction Program (TRRP) Testing,” presentation to the committee, September 5, 2007. 2 Question-and-answer session with BPBGT personnel and the committee, September 6, 2007.
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Review and Assessment of Developmental Issues Concerning the Metal Parts Treater Design for the Blue Grass Chemical Agent Destruction Pilot Plant BOX 3-1 The Technical Risk Reduction Program (TRRP) 05c Heat Transfer Test The TRRP #05c Heat Transfer test will be performed in accordance with Appendix R of the BGCAPP Design-Build Plan, using the minimum equipment arrangement and testing material (at the Parsons Technology Development and Fabrication Complex) necessary to accomplish the objectives outlined within this Test Protocol and the corresponding Test Plan (to be developed as a follow-on to this protocol). As currently recognized, the overall test program objectives for resolution of the issues identified are described below. Demonstrate design fixes to the PCAPP MPT Test Unit such as: seals, doors, bearings, projectile jamming, etc. as identified in the overall study protocol and the various reports and recommendations emanating from that effort. Demonstrate BGCAPP-specific design improvements such as: effect of projectile orientation, steam injection orientation, gas take-off orientation, tray design to improve heatup. Calibrate the CFD Model of the test Unit on VX 155 mm projectiles to serve as a basis for FOAK full scale unit modeling. Demonstrate treatment of simulated EBH rocket warhead debris. Demonstrate limited Secondary Waste treatment options to gather data for further effort with the CFD Model. Perform test runs and cycles of components to make observations of critical design parameters that apply to the FOAK unit under design—particularly those that affect the risk of scale-up to the full scale unit. These include, but are not limited to: projectile paint debris generation and accumulation, thermal expansion stresses and deformation points, interferences, Gaussian field measurements and localized heating effects, wall temperature distribution, etc. Major Test Acceptance Criteria The following test results are considered acceptable (Note: see test matrix acceptance criteria for specific values): Objective 1: Heat rate testing will be acceptable if 5X treatment is achieved as measured by temperature indicating for devices or paints (dosimeters, thermal indicating paints, thermocouples, optical pyrometer, etc.) values of at least 1000 degrees F for 15 minutes; with “coldest spot” thermal treatment duration times under 90 minutes this yields an overall tray duration of 105 minutes. This timing may be adjusted based on further CFD modeling underway for the new tray design and under-tray steam distribution header. New door structure travels without binding, operates smoothly with cycle times of no more than 60 seconds to open and 60 seconds to close. Actuating mechanism is not unacceptably heated or mechanically stressed. Two-axis door operating motion remains trouble free and the door seats to the main chamber with no fit issues. The shadowing is being addressed by redesign of the projectile trays, the superheated steam inlet header, and the off-gas outlet header. The choice of mounting projectiles nose up or nose down in the trays is still a concern for full-scale MPT projectile trays. The BPBGT intends to resolve this issue by further analysis using the full-scale CFD model results (see Chapter 4). Finding. The proposed redesigns for the projectile trays and headers to reduce “shadowing” of parts of the projectiles are appropriate. (See Chapter 4 for further information and support.) Recommendation 3-4. The proposed header and tray redesigns to reduce “shadowing” of parts of the projectiles should be tested at the full-scale MPT operating conditions at the fabrication facility. SECONDARY AND CLOSURE WASTE TREATMENT Pyrolysis testing of secondary waste simulants was carried out at Hazen Research Inc. (HRI, 2005). This was followed by MPT TRRP testing of secondary waste treatment at the Parsons facility in Kennewick, Washington, in 2007. Waste to Be Treated in the MPT A flow diagram of the BGCAPP waste treatment system is provided in Figure 1-1 in Chapter 1. Waste to be treated in the MPT includes the washed munitions bodies from the munitions washout system (MWS), solid residues from the EBH, and secondary and closure waste. Estimated secondary waste generation and MPT processing rates for BGCAPP are given in Table 3-1. Table 3-1 shows the waste streams in generic form: metal waste, butyls, PVCs, sludge, wood, and so on. Specific
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Review and Assessment of Developmental Issues Concerning the Metal Parts Treater Design for the Blue Grass Chemical Agent Destruction Pilot Plant Main Chamber seal is tight and sufficiently contributes to maintaining the oxygen content in the MPT under 3 % after the appropriate purge cycle is completed. The seal remains in place and intact with no pulling loose, damage or visible misalignment. Face plate and flange heat warpage is minimal (i.e. does not affect the ability of the door seals to function. Helium leak testing devices will be in place to accomplish seal integrity tests.) Conveyor bearings enable free rolling tray with full set of projectiles evenly with no visible binding or excessive wear or deformation (i.e., upon post-test disassembly, close inspection yields little or no evidence of galling, pitting, bearing material degradation, etc.). Objective 2: The Test Unit will perform as predicted by the CFD model within experimental accuracy. Nose up (PCAPP TRRP mode) and nose down (BGCAPP mode) projectile-loaded tray heat up times, in particular the so-called “cold spots” on predicted munition locations will perform as predicted within experimental accuracy; i.e. the location and times of the hotter munitions and the colder munitions are consistent with the CFD model. Projectiles will remain free in their tray locations and capable of ready removal after treatment. Alternative steam injection and main chamber gas removal orientation designed to mimic the FOAK unit installation will conform to the CFD model’s predicted “cold spot” heatup improvement effects and not degrade system performance. Objective 3: Miscellaneous metal parts originating from the EBH treatment of rocket warheads will reach 1000 degrees F for a minimum of 15 minutes within an MPT main chamber thermal treatment duration under 90 minutes. Although this is not an EBH-pacing cycle time. Objective 4: The limited secondary waste testing will be considered successful if design data can be obtained from the tray types, surrogate wastes, and heating profiles (low and high) to support further testing with actual secondary waste materials during plant systemization. Design data will consist of information and observations on the efficacy of different tray configurations, debris/particulate generation, treated waste consistency, etc. Data on heat transfer through various materials and loading configurations will be obtained to support CFD modeling. Objective 5: Success criteria for this objective is to gather enough information during the short testing time available to help reduce the risk that the FOAK unit will have either major design flaws or a reduced throughput when it is tested during the Factory Acceptance Testing at the end of its fabrication. The quantity and type of information that will satisfy this criteria is subjective. SOURCE: BPBGT, 2007d. waste streams that are expected to be treated using MPTs are the following: Solid residue from the EBHs, a stream that includes metal parts and elastomeric material, M2 squib booster assembly, segments of the shipping and firing tubes, and steel parts from the sheared rocket propellant sections of contaminated rockets. The M2 squibs are heat-sealed in polyethylene. These components are not decomposed in the EBH and must be “popped” within the MPT.3 Nose closures from projectiles. Personal protective equipment and other plastic and rubber items. Agent-contaminated wood. Other secondary waste that may be generated during operation, including miscellaneous metal parts, contaminated metal straps from the enhanced onsite containers, metal-reinforced hoses, metal piping, valves, and tools generated during facility operation. Other secondary waste that may be generated during closure, including solid residues, building components, and appurtenances. For several of the secondary waste categories above, agent-contaminated waste will be treated by chemical decontamination. When chemical decontamination does not prove successful (e.g., for agent-contaminated pallets), such waste will be treated in the MPT before off-site disposal. Secondary waste that is not agent-contaminated is not expected to be processed through the MPT (BPBG, 2004). 3 The rocket motor sections also include a squib in the M67 motor assembly. During normal operation these squibs are removed with the motor section and sent off-site. However, during the leaker campaign they will also be sent to the EBH and then to the MPT where they are destroyed.
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Review and Assessment of Developmental Issues Concerning the Metal Parts Treater Design for the Blue Grass Chemical Agent Destruction Pilot Plant TABLE 3-1 Solid Waste Generation and Processing Rate in the Metal Parts Treater Type of Waste Waste Creation During Operations (lb/week) Required MPT Processing Rate (lb/week)a Processing Time Needed (hours/week) Metalsb 698 2,598c 1.0 Butyls 104 25.5 4.1 PVCsd 762 100 7.6 Sludge 373 232 1.6 Wood 214 81 2.6 Total 2,151 aAs given in BPBG, 2006a. bAll metal waste can be processed in a single tray over a 1-hour period. cWeight of GB projectile bodies within a tray and is given for comparison only. dPVC, polyvinylchloride. SOURCE: Adapted from Sam Hariri, Process Design Lead, Bechtel Parsons Blue Grass Team, “Thermal Modeling to Support OTM Design,” presentation to the committee, September 5, 2007. Pyrolysis Testing of Secondary Waste Simulants A bench-scale test program was carried out at Hazen Research Inc. in 2005 using a muffle furnace. Four materials were subjected to pyrolysis: polytetrafluoroethylene (PTFE), butyl rubber, polyvinylchloride (PVC), and wood. These materials were obtained in the form of PTFE sample line tubing, butyl rubber boots with steel toes, PVC Lab Safety Supply (LSS) hose, and pallet wood. Butyl rubber boot material with no steel was also tested. Activated carbon was not tested because it is expected that this material will be treated off-site. One objective was to obtain information on gas generation during pyrolysis to confirm the design of the OTM. Another objective was to view the physical form of the solid residues from pyrolysis. The test materials were pyrolyzed under a nitrogen and steam atmosphere. Sample weight loss was recorded as a function of temperature as the temperature was increased to 1200°F. A summary of results is shown in Table 3-2. The amount of gas generated during heating to 1200°F ranged from 0.413 g of gas per gram of starting sample material for PVC hose to 1.00 g of gas per gram of starting sample material for PTFE. This information is useful for confirming the design of the BOX and associated equipment. Visually, the wood sample and the PVC LSS hose had shrunk in size during treatment, but were intact. The butyl rubber boot material had crumbled. As would be expected from the gas generation results, the PTFE tubing had essentially disappeared. TABLE 3-2 Summary of Results from Secondary Waste Testing Carried Out in 2005 Stream Material Tested at 1200°F PVCa Hose Wood PTFEb Rubber Feed, g 68.5 60.7 51.6 64.0 Residue, g 40.2 11.4 0.0 23.8 Weight change (loss to gas phase), g 28.3 49.3 51.6 40.2 Gas generated, g gas/g feed 0.413 0.842 1.00 0.628 aPVC, polyvinylchloride. bPTFE, polytetrafluoroethylene. SOURCE: Sam Hariri, Process Design Lead, Bechtel Parsons Blue Grass Team, “Thermal Modeling to Support OTM Design,” presentation to the committee, September 5, 2007. Technical Risk Reduction Program Testing of MPT Treatment of Secondary Waste TRRP testing of secondary waste treatment in the MPT was conducted at the Parsons fabrication facility in Kennewick, Washington, May 15-31, 2007. Three issues were identified for evaluation in the testing:4 Solid waste processing characteristics and rates: In coordination with the process and operations groups, establish the criteria and throughput processing rates for secondary waste and miscellaneous metal parts. Real-time volatile organic compound (VOC) monitors: Investigate and provide recommendations on the need for a real-time VOC or total organic carbon analyzer system for the MPT and OTM to mitigate OTM overload. Duct plugging: Investigate and provide recommendations on methods to mitigate the potential for downstream component plugging. One issue that is still being addressed by the BPBGT is the thermal destruction of the fuze detonators in the EBH waste stream. According to the TRRP test plan, approximately 360 of these items are produced from each EBH discharge. It is currently planned to send this waste to the MPT; however, the method of controlling the energetic releases in the MPT has not been identified. If not addressed properly, these releases could result in greatly increased maintenance requirements and possible damage to the MPT. A separate study is underway to investigate the potential effect of energetics remaining in the EBH debris as fuze remnants (BPBGT, 2007b). 4 Samuel Hariri, Process Design Lead, Bechtel Parsons Blue Grass Team, “Thermal Modeling to Support OTM Design,” presentation to the committee, September 5, 2007.
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Review and Assessment of Developmental Issues Concerning the Metal Parts Treater Design for the Blue Grass Chemical Agent Destruction Pilot Plant The simulated waste materials that were treated in the MPT were these: Actual butyl rubber toxic agent protective gear: M3 suits, aprons, boots, gloves; Surrogate demilitarization protective ensemble material (30 mil poly sheet) and poly drum liners; Ethylene propylene diene monomer chemical hose (non-PVC [LSS] air hose surrogate); Spill pillows saturated with ethylene glycol (hydraulic fluid stimulant); Simulated EBH rocket warhead debris (fuze mockups, cut-to-length steel tubes, poly tube); Scrap piping components (large dense valves and pipe); and Simulated equipment test hardware rocket shipping and firing tube sections and cut aluminum rocket bulkheads from the rocket-cutting machine TRRP. Waste was fed on mini-waste incineration container (mini-WIC) trays, half the length but otherwise identical to the baseline-design WICs. WIC trays were “stacked” using fabricated tray inserts to test the concept of “double-decking.” The testing at Kennewick was limited to nonhalogenated materials and did not include EBH energetic materials because of permitting considerations. Waste feeds were limited to 20 lb of organic constituents per tray since the CATOX capacity was equivalent to the VOC loading from 30 lb/h of waste. The results indicated the following:5 Chamber oxygen content consistently fell from the initial value at tray insertion to less than detectable (<0.01 percent) within minutes after tray insertion. The process logic controller, which recorded O2 levels to 0.0001 percent, indicated that the O2 level continued to drop, stabilized, and eventually rose rapidly back above the 0.01 percent level. This duration was generally on the order of 60 minutes.6 The BPBGT pyrolysis study concluded that VOC/total organic carbon monitors are not appropriate for determining the completion of pyrolysis when treating organic-containing materials such as secondary waste (BPBGT, 2007d). The off-gas treatment CATOX experienced temperature rises that exceeded the CATOX operating limits. The temperature spikes varied for different types of waste. This was not considered a concern by the committee because the full-scale BOX has a higher temperature rating. Sharp, but low-level, spikes of VOCs and carbon monoxide were measured in the outlet air lock. These spikes are believed to be contributors to the rises in CATOX noted in the preceding observation and are not considered a concern for the BOX unit. Also, since nitrogen purge is used in the outlet air lock, ignition of these materials did not occur. Wood and cotton cloth waste did not flame when the tray was removed. Most treated waste appeared reduced to nonorganic constituents and was readily removed from the WIC by vacuum or brush and pan. The mini-WICs showed very little thermal deformation. All dosimeters indicated that treatment at 1000°F for 15 minutes was met within the 120-minute standard residence time. Oxygen level response indicated that all organic material was gone after 75 minutes. Remaining issues of concern included steam flow into the air locks immediately on door opening, and smoking of some types of waste shortly after the tray was placed in the chamber. Estimated weekly secondary waste processing rates were developed using an ASPEN7 model, projecting BGCAPP waste generation rates to estimate weekly process time anticipated in the MPT. Inspection of duct interiors during disassembly of the off-gas treatment system showed no buildup of tars or chars that would be indicative of full-scale operational cleanout or downtime issues. However, the amount and rate of surrogate material processed was much lower than will be experienced in the full-scale MPT. Finding. The range of secondary waste materials tested was limited in comparison to the anticipated range of waste to be treated in the full-scale MPT. Furthermore, halogenated materials were excluded because the TRRP MPT permit could not be readily changed to allow such materials. Recommendation 3-5a. The BPBGT should perform more-comprehensive testing prior to systemization, drawing from operator experience at prior operating plants. This testing should include waste materials and waste flow rates representative of those encountered during closure, as well as miscellaneous secondary waste from operations and maintenance and any possible residual energetics. Recommendation 3-5b. The use of halogenated materials should be minimized in operations and maintenance activities wherever possible, and selection of materials should 5 Bechtel Parsons Blue Grass Team, “Secondary Waste Testing 15–31 May 2007,” presentation to the committee, September 5, 2007. 6 Bechtel Parsons Blue Grass Team, “Secondary Waste Testing 15–31 May 2007,” presentation to the committee, September 5, 2007, slide 253. 7 ASPEN is chemical engineering processing software. For more information, see http://www.aspentec.com/products/process-engineering.efm.
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Review and Assessment of Developmental Issues Concerning the Metal Parts Treater Design for the Blue Grass Chemical Agent Destruction Pilot Plant anticipate halogenated materials and the possible corrosive nature of steam. Also, testing prior to systemization should include halogenated feeds at the rate expected from plant design and operations. Finding. Inadequate data were collected to serve as the basis for determining processing rates for secondary waste. Waste loading in trays during the TRRP testing may not be representative of loading configurations during operation (e.g., weight per tray, double-stacking, and so on). Recommendation 3-6. Additional testing is needed to verify the complete destruction of secondary waste and to verify appropriate feed (e.g., tray and loading) configurations that render effective treatment of the variety of types of secondary waste. Alternative Treatment and Disposition of Secondary Waste In general, secondary waste can be shipped off-site safely if it meets one of two criteria: (1) if analysis shows levels less than the applicable waste control limits (WCLs)8 or (2) if the waste has been subjected to thermal treatment at 1000°F for 15 minutes. The second criterion, formerly called treatment to 5X, was a requirement for off-site shipment until June 2004 when the WCL criteria were introduced. The BPBGT plans to heat all secondary waste to 1000°F for at least 15 minutes in the MPT. The advantage of that approach is that documentation is straightforward and no further analysis need be done before shipment. The disadvantage is that many of the secondary waste materials form chars and tars at that temperature that can foul the trays and the OTM. Permits under the Resource Conservation and Recovery Act of 1976 for baseline incineration facilities generally consider waste to be nonhazardous for chemical agents and suitable for off-site shipment if extractive analysis of the waste shows the concentration of agent to be less than the WCL (NRC, 2007). The analysis can be done using the toxicity characteristic leaching procedure, as described in the Environmental Protection Agency’s publication SW-846, or by using a different methodology approved by the state regulatory agency (NRC, 2007). In order to be able to use a WCL criterion, the BPBGT would need to get approval from the State of Kentucky on the acceptable WCL for each agent and the method of analysis to be used. If approval is obtained, each secondary waste batch suspected of being agent-free may be tested. If it meets the WCL, it can be shipped off-site with no further treatment. If it does not meet the criterion and is likely to char or tar at 1000°F, it can be treated at a lower temperature in the MPT and the end product can be analyzed to verify that it meets the WCL. By lowering the temperature to ~500° F for 1 to 2 hours, six nines (99.9999 percent) agent destruction and removal efficiency should be achievable, and char and tar formation should be greatly reduced. Finding. In many cases, secondary waste can be shipped off-site for treatment and disposal in a safe manner. Finding. For waste that cannot be shipped off-site, the MPT could be used at a lower temperature for treating secondary waste to reduce tar and char load. Recommendation 3-7. To reduce the technical risks in treating secondary waste in the MPT, the BPBGT should continue to strive to send as much secondary waste off-site as possible, and should obtain the necessary permits to allow lower-temperature processing in the MPT. Finding. TRRP MPT testing confirms that treatment of metal parts and secondary and closure waste can be performed at 1000°F for 15 minutes in a suitably sized MPT if enough time is allowed for the treatment and if the testing recommended in Recommendation 2-1 is completed. 8 WCLs and the analytical methods required to demonstrate that they have been achieved vary by state. In general, the WCL is defined as 20 parts per billion (ppb) for GB and VX and 200 ppb for HD, as determined by the Environmental Protection Agency’s (EPA’s) toxicity characteristic leachate procedure (TCLP) applied to the residuals from the metal parts treater. The WCL may also, or additionally, be based on agent concentration in the air space above the containerized waste treatment residuals. Minimum required levels are typically 1 STEL (short-term exposure limit)—0.0001 mg/m3 for GB, 0.00001 mg/m3 for VX, and 0.003 mg/m3 for HD.