Disposal of Activated Carbon from Chemical Agent Disposal Facilities (2009)

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Summary For the past two decades, the United States has been processes and equipment suitable for use by the Army destroying its entire stockpile of chemical agents. At (considering both on-site and off-site usage), including characterization and pre-treatment requirements the facilities where these agents are being destroyed, •  the foregoing context, assess the scientific support need- in effluent gas streams pass through large activated carbon ed for obtaining regulatory approvals at CMA facilities. filters before venting to ensure that any residual trace vapors of chemical agents and other pollutants do not In response to this request, the NRC Board on Army escape into the atmosphere in exceedance of regulatory Science and Technology assembled the Committee to limits. All the carbon will have to be disposed of for Examine the Disposal of Activated Carbon from the final closure of these facilities to take place. Heating, Ventilation, and Air Conditioning Systems at In March 2008, the Chemical Materials Agency Chemical Agent Disposal Facilities. After discussion (CMA) asked the National Research Council (NRC) with the sponsor, the committee undertook to consider to convene a committee to study, evaluate, and recom- the disposition of all the carbon, exposed or unexposed mend the best methods for proper and safe disposal of to chemical agent, at the facilities. the used carbon from the operational disposal facilities. This report examines various approaches to handling The statement of work reads as follows: carbon waste streams from the four operating chemical agent disposal facilities that use incineration technol- Statement of Task ogy developed by the Army. The approaches that will be used to dispose of carbon waste at each facility will The National Research Council will establish an ad hoc ultimately be chosen bearing in mind local regula- committee to: tory practices, facility design and operations, and the •  examine the current heating, ventilation, and air condition- characteristics of agent inventories, along with other ing (HVAC) systems of the U.S. Army's Chemical Materi- factors such as public involvement regarding facility als Agency (CMA) that use activated carbon and consider the overall quantity and characteristics of the CMA HVAC operations. This report is intended to analyze and assess secondary wastes essential information on the various approaches for dis- •  assess the current plans and path forward for contaminated posing of waste carbon from these facilities whether or carbon management and disposition at Army chemical not the carbon has been exposed to agent. This should agent disposal facilities enable readers to understand the technical reasoning •  evaluate commercial and established industry alternatives for contaminated carbon disposal, i.e. best practices, underlying the committee’s findings and recommen- dations. Specific findings and recommendations are found in the individual chapters; the key findings and Note that what are termed “carbon filters” in Army parlance are recommendations (General Findings 1-5 and General more accurately termed “carbon adsorption beds.” Recommendations 1-5) derived from the individual  

 DISPOSAL OF ACTIVATED CARBON FROM CHEMICAL AGENT DISPOSAL FACILITIES chapters are presented at the end of this Summary and TABLE S-1  Summary of Sources and Estimated in Chapter 7. Inventories (in Pounds) of Carbon Exposed to Agent at Only three types of filter units are expected to ever CMA Incineration Sites During Operations and Closurea be exposed to agents under normal operating condi- MDB M-40 Mask tions: (1) those that filter the heating, ventilation, and Site ACS Laboratory HVAC Canistersb Other air conditioning (HVAC) air from the munitions demili- ANCDF 3,600 <100 153,800 1,400 UMCDF 4,800 <100 47,500 2,100 tarization building (MDB), (2) the filters installed on TOCDF 200 15,300c 159,000 3,100 20,800d the vent line from the agent collection system storage PBCDF 1,200 <100 95,600 <100 tanks, and (3) the canisters for the M-40 protective masks used by workers. The carbon from the initial    Total 9,800 15,300 455,900 6,600 20,800 banks of MDB HVAC air filters accounts for by far the aWeights may include carbon, carbon tray materials, and packaging. Information is as of September 29, 2008. Estimates of exposed carbon made largest share of exposed carbon. All of the other filter on basis of anticipated on-site treatment. Quantities have been rounded. units installed to protect personnel or the environment bCarbon from M-40 mask canisters, while normally not exposed to agent, will never have been exposed to agent unless some is generally expected to be treated as exposed at most sites in view of the upset had occurred (e.g., release of agent to the atmo- relatively small amounts involved. cThis carbon amount is the result of the significantly larger amounts sphere outside the MDB). and greater variety of materials tested over the longer duration of TOCDF The MDB, which is where the munitions or con- operations compared to other sites. tainers are opened and treated, has a cascading HVAC dThis carbon amount is the result of a ton container sampling operation unique to the site. system that is designed to move ventilation air from clean, uncontaminated areas to areas having increasing SOURCE: Adapted from information provided to the committee by Timothy Garrett, Site Project Manager, ANCDF, as of September 29, 2008. levels of agent contamination. The HVAC system then discharges the air through banks of activated carbon filters. Each bank of the filter units, which are arranged in series, contains 48 metal trays each holding approxi- mately 50 lb of carbon. An important feature of the The permits for the chemical agent disposal facili- system design is that operational procedures normally ties at Anniston, Alabama, Pine Bluff, Arkansas, and allow only the carbon in Banks 1 and 2 of the multi- Tooele, Utah (ANCDF, PBCDF, and TOCDF) set the bank adsorber units filtering the plant HVAC air to ever WCL as 20 ppb for nerve agents GB and VX and 200 be exposed to agent. The carbon from Banks 3-6 of the ppb for mustard agent, while the facility at Umatilla, HVAC filter units and the carbon from the pollution Oregon (UMCDF) sets PCCs, which serve a similar abatement system (PAS) filtration system (PFS) on purpose, at 13 ppb for VX, 16 ppb for GB, and 152 ppb each of the incinerators make up the bulk of the unex- for mustard. The primary analytical methodology for posed carbon. Estimates of the amounts of carbon that characterizing a waste at most of the chemical agent must be disposed of from the indicated sources at each disposal facilities is set forth in EPA Publication SW- site are tabulated in Tables S-1 and S-2. The ratio of 846; it includes the toxic chemical leaching procedure unexposed to exposed carbon is approximately 4 to 1. (TCLP), which is required to determine if a waste meets The disposal of the exposed and unexposed carbon the toxicity characteristic definition. is regulated under the Resource Conservation and The existing requirements to transport activated Recovery Act (RCRA) by the respective state regula- carbon off-site for disposal are stated in each facility’s tory agencies. Each facility has been issued a RCRA RCRA permit (Table S-3). Any changes require apply- permit under the applicable state regulations. These ing for a modification to the permit—the approval permits establish waste characterization requirements, process takes approximately 1 year. Planned applica- pertinent sampling/analysis methodologies, waste disposal methods, operating parameters, and closure Brian O’Donnell, Chief, Secondary Waste, Closure Compli- requirements for each facility. The state-issued RCRA ance, and Assessments, CMA, “Transportation risk assessment,” permits for all of the disposal facilities specify waste Presentation to the committee, July 24, 2008. 40 C.F.R. 261.24(a). A waste is considered hazardous for toxic- control limits (WCLs) or, for Oregon, permit compli- ity if the extract from the procedure contains a listed contaminant ance concentrations (PCCs) in parts per billion (ppb) above a specified concentration, with mercury listed at 0.2 mg/L of chemical agent below which a waste may be shipped (Table 1). off-site for disposal. 

SUMMARY  TABLE S-2  Summary of Sources and Estimated Inventories (in Pounds) of Unexposed Carbon Used at CMA Incineration Sites During Operations and Closurea PFS Sulfur- PFS Carbon MDB Impregnated Control Site (Regular) Laboratory HVAC Carbon Room Other ANCDF 115,500 15,400 414,700 69,300 15,400 12,400 UMCDF 270,000b 10,600 95,000 200,000b 5,300 17,300 TOCDF 0c 6,300 318,000 240,000d 5,000d 2,500d PBCDF 80,800e 15,900 127,500 48,500f 8,000 14,400    Total 466,300 48,200 955,200 557,800 33,700 46,600 aWeights may include carbon, carbon tray materials, and packaging. Information is as of September 29, 2008, unless otherwise noted. Estimates of unexposed carbon made on basis of anticipated off-site treatment. Quantities have been rounded. bInformation updated as of March 17, 2009. cPFS was only recently added at TOCDF for the processing of mercury-contaminated mustard agent and therefore only sulfur- impregnated carbon is to be used. dInformation updated as of March 19, 2009. eInformation updated as of March 18, 2009. Of this amount, 48,500 lb has already been shipped off-site. fInformation updated as of March 18, 2008. SOURCE: Adapted from information provided to the committee by Timothy Garrett, Site Project Manager, ANDCF, as of September 29, 2008. TABLE S-3  Current Status of Permit Requirements for Shipping Carbon Off-site from Chemical Agent Disposal Facilities Facility Requirement of the Existing Permit Planned Modification Application ANCDF Carbon exposed to <1 STL may be shipped off-site.a HVAC carbon >WCL after extractive analysis to be shipped off-site in Carbon exposed to >1 STL must undergo extractive analysis prior accordance with bounding transportation risk assessment. to shipment. Munitions demilitarization building HVAC Bank 1 carbon appears to Carbon that tests <WCL may be shipped off-site. be >WCL for GB. Filters from the agent collection system will be incinerated on-site. UMCDF Off-site shipment of agent-free carbon allowed if agent The UMCDF plans to submit a Permit Modification Request to concentration is less than the PCC: 16 ppb for GB, 13 ppb for VX, incorporate the agent extraction method for spent carbon into the and 152 ppb for mustard. Hazardous Waste Permit WAP following the programmatic validation of the method. TOCDF All carbon must be processed by carbon microminiaturization Ship all carbon from the pollution abatement system filtration system system and subsequently combusted in the deactivation furnace and from the heating, ventilation, and air conditioning (HVAC) Banks system.b 4-6 off-site. Considering using autoclave on remaining carbon until VSL <1 then shipping off-site. PBCDF The WAP requires on-site incineration of exposed carbon that is None. shown by extractive analysis to be greater than 20, 20, and 200 ppb for GB, VX, and H, respectively. The WAP allows off-site shipment to a TSDF for spent carbon that is shown by extractive analysis to be less than 20, 20, and 200 ppb for GB, VX, and H, respectively. Unexposed carbon can also be shipped, and generator knowledge is allowed in the determination of “unexposed.” NECDF Used agent-contaminated carbon is considered a listed hazardous None. waste (Waste Code 1001). However, extractive analysis was done to satisfy CMA bounding transportation risk assessment requirements. Agent-contaminated carbon has been shipped to a TSDF (a hazardous waste incinerator) for treatment. aThe one STL for GB and VX is 20 ppb; for HD, it is 200 ppb. bAlthough this is the existing requirement, the state and TOCDF have agreed that carbon will be stored until another treatment method is approved. SOURCE: Personal communications between Timothy Garrett, Site Project Manager, ANCDF, and Margaret Novack, NRC study director, February 24, 2009, February 25, 2009, and February 27, 2009. 

 DISPOSAL OF ACTIVATED CARBON FROM CHEMICAL AGENT DISPOSAL FACILITIES tions for permit modifications are also shown in the the ANCDF Bank 1 carbon indicate that the residual table. The regulations generally specify that the carbon GB (~129 ppb) is above the WCL limit (20 ppb), will require extractive analysis to confirm that agent which means the carbon will not be transportable concentration(s) are below the respective WCLs or under the present permit. However, carbon containing PCCs. GB at more than 20 ppb could be transported off-site Although all three chemical agents are strongly if the transportation risk assessment (TRA) approved adsorbed on coconut shell activated carbon, they all by state regulators and procedures was implemented react with the moisture that is also adsorbed on the to satisfy the bounding TRA values. These values are carbon to form the expected hydrolysis products. In a function of accidental release scenarios assumed in 2007, several carbon samples from Banks 1 and 2 of the the assessment and the frequency established for such MDB HVAC filter unit at ANCDF were analyzed for release scenarios. residual GB and VX at both government and contractor In response to the third bullet in the statement of surety laboratories. task for this study, the committee surveyed the common These analyses verified that the agents GB and VX industrial practices for managing activated carbon. In decompose by hydrolysis with the adsorbed water on commercial and industrial applications, activated car- the carbon. The amount of GB that must have been bon finds extensive use as an adsorbent for removal of adsorbed on Bank 1 carbon during processing of GB a wide range of contaminants from liquids and gases. munitions in the MDB is evidenced by the 13 wt percent Demand for activated carbon in the United States of its hydrolysis product, isopropyl methylphosphonic was 363 million pounds in 2005, split approximately acid (IMPA), which was found on the carbon by solid equally between granulated activated carbon and pow- state magic angle spinning (MAS) nuclear magnetic dered activated carbon. The activated carbon used in resonance (NMR). In comparison, only a trace amount chemical agent disposal facilities is granulated. Acti- of the VX hydrolysis product, ethyl methylphosphonic vated carbon is also used to adsorb a product such as a acid (EMPA), was found on carbon from Bank 1. This solvent from a process stream. In such applications, the small amount of the hydrolysis product is attributed to adsorbed product is subsequently desorbed on-site for the low volatility of VX. Extractive analysis of HVAC reuse. This last step, known as “carbon regeneration,” filter unit carbon samples from NECDF by the system differs from “carbon reactivation,” which is a treatment contractor laboratory indicated the presence of volatile process whereby adsorbed materials (adsorbates) on the VX impurities, hydrolysis by-products, and degrada- carbon are destroyed and the structure of the activated tion products of the aminothiol group. At this time, no carbon is restored for reuse. Reactivation is carried MDB HVAC carbon sample exposed to mustard agent out in either a rotary kiln or multiple hearth furnaces HD from a chemical agent disposal facility is available where the carbon is heated in the presence of steam to for laboratory analysis. 1800°F. The shipping of agent-exposed carbon to off-site dis- There are essentially three treatment and disposal posal facilities will require determination of the loading methods used for treating activated carbon from com- of agent on the carbon on a mass basis (mass of agent mercial operations: (1) reactivation, (2) landfill, and per mass of carbon). For parts-per-billion levels of (3) incineration. If carbon from commercial industrial detection of residual agents on carbon, solvent extrac- operations has been reactivated, vendors offer two tion of the adsorbed phase from the carbon sample options. One is to return the reactivated carbon to its followed by gas chromatography/mass spectrometry former user. The other is to combine it with reactivated (GC/MS) analysis is being pursued. The Bank 1 carbon carbon from other sources and resell it. Reactivation is removed at ANCDF was analyzed by this method at attractive to industrial users principally because it is Southwest Research Institute to determine the amounts less costly than disposal and purchase of freshly made of GB and VX remaining on the carbon. VX was below activated carbon. the WCL, but GB was above it. The GB result has When varying amounts of mercury were discovered been interpreted as a sign that GB re-forms from the in the mustard agent HD/HT ton containers at TOCDF, hydrolysis products in the solvent during the extraction PBCDF, and UMCDF, CMA was required to develop process. A way was found to limit this re-formation to a strategy to prevent emission of mercury during the ~6 ppb, but this modification to the standard method is incineration of HD/HT. Unlike agent, mercury persists not considered valid until other laboratories have repro- in one form or another in the offgas leaving the PAS duced the results. Early (unvalidated) measurements on units of the incinerators. Testing results have shown 

SUMMARY  that using sulfur-impregnated activated carbon in the polyethylene drums, which were shipped by truck to PFS units during HD/HT processing is a good way to the Veolia Environmental Services Facility in Port control mercury emissions. Arthur, Texas, where the used carbon and drums were The HD/HT stockpiles contain bulk storage ton incinerated without opening the drums. Bags contain- containers and munitions. All HD/HT ton containers ing carbon and agent at ≤1VSL were shipped to Veolia have been found to contain some amount of mercury. without drumming and incinerated as is. Some HD/HT munitions may also contain mercury. The NECDF permit had no requirement for sam- The semisolid heels in the ton containers at TOCDF pling and analysis of the used carbon before shipment are the largest sources of mercury. Given the diverse to an off-site treatment, storage, and disposal facility uses of activated carbons at chemical agent disposal (TSDF). Under this permit NECDF managed the carbon facilities and the focus of this report on disposal that had been exposed to VX as a designated hazardous options for activated carbon from these facilities, it waste and shipped it off-site to Veolia for incineration. is important to explain that the adsorption of mercury NECDF also shipped approximately 220,000 pounds onto activated carbon and the adsorption of agent onto of used unexposed carbon to Calgon Carbon Corpora- activated carbon occur in physically different carbon tion for reactivation. This used unexposed carbon came filter units and at separate locations during HD/HT from Banks 3 through 6 of the HVAC filter units. thermal destruction operations. There is virtually no At ANCDF, PBCDF, and UMCDF, operating per- opportunity for both mercury and agent to be adsorbed mits allow thermal treatment (1000°F for more than 15 onto the same carbon bed during normal operations at minutes) of exposed carbon in the metal parts furnace. chemical agent disposal facilities. Activated carbon is Presently, this practice is being used to treat the few expected to be exposed to mercury exclusively in the carbon filter trays from the vent line of the agent col- PFS units, while it will be exposed to agent primarily lection system (ACS) storage tanks and carbon from in the initial HVAC filter systems. Although the ton the canisters of the M-40 protective masks. During this containers will be opened to the atmosphere in the thermal treatment, the trays and canisters of carbon are MDB rooms, mercury volatilization will be negligible held much longer than 15 minutes to ensure complete because the vapor pressure of mercury in its elemental oxidation of the carbon and prevent it from smoldering form is very low. Mercury salts would not have any when it is removed from the metal parts furnace. The vapor pressure. TOCDF is planning to treat agent-exposed carbon in The closure plan for the Johnston Atoll Chemical an autoclave to achieve decontamination sufficient for Agent Disposal System (JACADS) required all used off-site shipment. This concept was being tested as this carbon to be incinerated on-site by micronization. The report was being written. used carbon was first pulverized to a powdery consis- CMA has proposed managing the carbon by on-site tency in a carbon micronization system and then blown disposal of the small quantities of highly contaminated into the deactivation furnace system, where it was carbon from the ACS storage tank vent lines and the incinerated. The committee has determined from the carbon from M-40 gas mask canisters. Off-site ship- experience gained during the closure of JACADS that ment has been proposed for all of the other carbon this process presents hazards, including the potential (exposed and unexposed) for disposal at a qualified for serious dust explosions. TSDF, either by incineration or in a landfill. For all At the closure of the Aberdeen Chemical Agent unexposed carbon, shipment will be based on generator Disposal Facility (ABCDF), the used carbon filters knowledge that the carbon has never been exposed to (carbon contained in metal trays) were double bagged agent. For exposed carbon, off-site disposal is based in polyethylene. The bags that had agent vapor screen- on using approved sampling methods to determine the ing levels (VSLs) of >1 were then placed in 95-gallon amount of agent present in each polyethylene drum and comparing that amount to the amount allowed by a bounding TRA prepared and approved by CMA for Vapor screening levels (VSLs) and short-term limits (STLs) are use on all agent-contaminated secondary waste ship- equivalent names (specified in RCRA operating permits) for the limits used in waste transport and disposal. They also supplement short-term exposure limits (STELs) for protecting workers’ health is determined from air sampled for about 5 minutes instead of the during plant operations as waste is generated and moved to storage 15 minutes of exposure applicable to STELs. A value of 1 VSL for areas within the plant. VSL and STL concentrations vary by agent GB, VX, and HD is equal to 0.0001 mg/m3, 0.00001 mg/m3, and and are the same values as STELs except that a VSL measurement 0.003 mg/m3, respectively. 

 DISPOSAL OF ACTIVATED CARBON FROM CHEMICAL AGENT DISPOSAL FACILITIES ments. Use of the bounding TRA at operating disposal liability. The choice of disposal method and treatment, facilities is expected to require acceptance by the state storage, and disposal facility will be dictated by what- regulators for each site and for each state through which ever other contaminants are present on the carbon. the materials are proposed to be moved. Use of the bounding TRA for exposed carbon General Finding 2.  Unless there is an unexpected will require special sampling and analysis since the upset resulting in contamination with agent, all of the adsorptive properties of activated carbon prevent sulfur-impregnated carbon that is to be used in the the application of vapor screening to determine the pollution abatement system filtration systems will not amount of agent in the container. This methodology have been exposed to agent. Thus, based on genera- poses at least two challenges: The CMA must validate tor knowledge the carbon can be sent off-site without a sampling technique that ensures that agent-exposed further analysis for chemical agents. This carbon can carbon samples are representative of the total mass of be treated as a hazardous waste contaminated with carbon in the shipping container. The CMA must also mercury. show that the extractive analysis procedure to be used accurately measures the agent present on the exposed General Recommendation 2.  All of the sulfur- carbon at the ppb level. impregnated carbon used in the pollution abatement The committee believes that adding decontamination system filtration systems and not involved in an unex- solution (NaOH) to the drums in which the exposed car- pected upset condition at a chemical agent disposal bon would be shipped off-site is a potentially attractive facility should be sent off-site. This carbon should be method for ensuring the safety of off-site shipments. treated as a hazardous waste that is contaminated with How much decontamination solution should be added mercury. must be determined as should how to ensure adequate wetting of carbon surfaces to achieve decontamination General Finding 3.  Treatment of all of the exposed at levels safe for shipment. carbon on-site in the metal parts furnace would seri- An additional option applicable to unexposed carbon ously delay the closure of the currently operating (approximately 80 percent of the total carbon) may be Chemical Materials Agency chemical agent disposal disposal by transfer to a reactivation contractor. This facilities. provides a path for the reuse of unexposed carbon, thereby reducing the cost of its disposal. Such an General Recommendation 3.  Only the carbon filter arrangement should be contingent on termination of trays from the agent collection system tank vent lines the Army’s ownership of and liability for the carbon as and the canisters from the M-40 protective masks soon as it is transferred to the reactivation contractor. should be treated on-site in the metal parts furnace when the metal parts furnace is not performing its pri- mary function of treating metal parts or other wastes. GENERAL FINDINGS AND RECOMMENDATIONS General Finding 1.  About 80 percent of all the used General Finding 4.  Nerve agents GB and VX and activated carbon that has been or will be generated at mustard agent have been shown to degrade on activated the chemical agent disposal facilities operating under carbon to their usual hydrolysis products by reacting the Chemical Materials Agency has never been exposed with the moisture adsorbed on the carbon. This occurs to agent and can be treated as ordinary hazardous waste. both while the carbon is in use and after, during storage. This includes the carbon from Banks 3 to 6 of the heat- Of the known analytical results, the concentrations of ing, ventilation, and air conditioning filter units and the VX that remain on carbon samples from heating, ven- bulk carbon from the filter beds of the pollution abate- tilation, and air conditioning Bank 1 at the Anniston ment system filtration system. Chemical Agent Disposal Facility appear to be below the waste control limit (WCL) of 20 parts per billion. General Recommendation 1.  All unexposed carbon However, the remaining concentration of GB appears (as determined by generator knowledge) should be dis- to be about 130 parts per billion, well above the WCL posed of off-site as a hazardous waste without further of 20 parts per billion. Thus, the carbon that has been chemical analysis for agent or sent for reactivation if exposed to GB cannot be sent off-site based on the a contractor will accept it and assume ownership and waste control limits where those limits have been nego- 

SUMMARY  tiated as permit compliance limits. The concentration of proper permit conditions to ship exposed carbon mustard that remains on the carbon filters had not been off-site based on the transportation risk assess- measured at the time this report was prepared. ment and the validated analytical methods. • Adding caustic solution to the drums. If the addi- General Recommendation 4.  Carbon that has been tion of caustic (NaOH) decontamination solution exposed to agent should be sent off-site under one of to a drum of exposed carbon wets the carbon, the the following arrangements: caustic will hydrolyze the agents remaining on the exposed carbon to below the WCL or PCC. The • Use of waste control limits (WCL) or permit drum containing the decontaminated carbon and compliance concentrations (PCC). If the agent decontamination solution can then be shipped off- concentrations on the exposed carbon are below site. The method of applying the decontamination the waste control limits or the permit compliance solution must be negotiated and approved by the concentrations, the carbon can be shipped off-site facility’s regulatory authority. Analysis for agent for proper disposal at a waste treatment facility on the carbon should not be necessary with this licensed to receive and treat this waste under arrangement. existing regulations. For this arrangement it will be necessary to develop and validate analytical General Finding 5.  Environmental Protection Agency methods that accurately measure agent concentra- Method 3571 appears to have provided an improved tion for both GB and mustard. The methods must method detection limit for extractive analysis of VX on be capable of analyzing the agents on carbon that the Bank 1 carbon sample from the Anniston Chemical has been exposed to all three agents and that will Agent Disposal Facility, but it must still be validated. have both the agents and their respective degra- Neither Environmental Protection Agency Method dation products from hydrolysis adsorbed on the 3571 for HD nor modified Method 3571 for GB, which carbon. appears to minimize re-formation of GB during extrac- • Use of a transportation risk assessment. By using tion and analysis, had been validated at the time this the precedent negotiated at Aberdeen Chemical report was being prepared. Agent Disposal Facility, if the mass of the agent on the carbon in a drum is less than specified by General Recommendation 5.  Both the original Envi- the Chemical Materials Agency transportation ronmental Protection Agency Method 3571 and the risk assessment (see Table 7-1) but >1 VSL, the modified Method 3571 must be validated for use on car- drum can be transported to a treatment, stor- bon exposed to all three agents (GB, VX, and mustard) age, and disposal facility. Each chemical agent since the chemical agent disposal facilities expect to disposal facility will have to negotiate with operate without changing out the heating, ventilation, the appropriate regulatory authorities to ensure and air conditioning filter units before closure.