6 CCR 1007-3-8.72 - Basis and Purpose

These amendments to 6 CCR 1007-3, Parts 261 and 268 are made pursuant to the authority granted to the Solid and Hazardous Waste Commission in § 25-15-302(2), C.R.S.

Mustard Agent Amendments

These amendments revise the K901 and K902 mustard agent listings in § 261.32(a) (Hazardous Waste from Specific Sources) and Appendix VII of Part 261 (Basis for Listing Hazardous Waste), and add the K901, K902, P909 and P910 listings to the Treatment Standards for Hazardous Waste table in § 268.40 of the Colorado Hazardous Waste Regulations (6 CCR 1007-3). These amendments also correct a typographical error in the header of the table in § 268.40.

The Colorado Hazardous Waste Regulations, 6 CCR 1007-3, Part 261, Subpart B, allow chemicals or other materials that are solid wastes to be added to the hazardous waste listings if the chemicals can be shown to meet any one of the criteria listed in § 261.11, and these listings may be revised based upon relevant information.

In previous rulemakings (§ 8.30, § 8.46, and § 8.48), the Commission determined the reason for the listing of chemical munitions on the basis of the available information that the chemical agents (HD and HT) were toxic as compared to the regulatory criteria for listing a hazardous waste found at 6 CCR 1007-3, § 261.11(a), and that there was adequate justification to add these Mustard Agents to the P-listed wastes found in § 261.33 of the regulations by adding waste codes P909 and P910 for the H and HD forms of Mustard Agent (CAS # 505-60-2) and the HT form of Mustard Agent (CAS# 505-60-2 and CAS # 63918-89-8), respectively. At the time of the original listings, the regulatory evaluation was focused upon the EPA determination that Mustard was a reactive waste due to its propensity to rapidly react with water to form hydrogen sulfide as well as hydrochloric acid, that the toxicity of Mustard Agents met the definition of an acutely toxic hazardous waste found at both § 261.11 (a) and § 261.11 (a)(2), and that the Army alleged that it had conservatively chosen to apply the toxicity characteristic waste codes applicable to metal constituents (the "RCRA metals", Arsenic, Barium, Cadmium, Chromium, Lead, Silver, Selenium, and Mercury), or D004 - D011.

At the time of these previous rulemakings, the Commission was acting upon available information, but better, more definitive, information has come to hand that indicates that other consequential constituents are present, that themselves, warrant a revision of the initial listing actions.

Background Documents

The Army, in compliance with regulatory requirements associated with Interim Status with respect to their stockpile storage mission, submitted a Part A Permit Application which details what they believed to be the constituents of the munitions in storage. This application is attached to this rulemaking as Exhibit 1.

The Army, in compliance with regulatory requirements to characterize these munitions, produced and presented to the Division the Munitions Assessment and Characterization Report (the "MACR"). This document was classified as a For Official Use Only ("FOUO") document which restricts this information to only those with a need to know the contents in an official capacity. Since the time of the original Division briefing to the Commission on these revisions to the listing specifications, on August 18, 2009, the Army has reclassified sections of this document to allow the general release of selected segments of this information to the public record. This reclassified document is attached to this rulemaking as Exhibit 2.

The Division, in concert with the regulatory and technical review of the submitted MACR and other waste characterization data for mustard agent, extracted a list of constituents found within, or associated with the mustard housed in the agent cavities of these munitions. This list of constituents is attached to this rulemaking as Exhibit 3.

The information found in Exhibits 1, 2, and 3 concerning the constituents found in or associated with mustard did not contain any information that was useful in determining the magnitude, or concentration of any of the constituents found in the chemical agent. However, prior to and during the acquisition of the information found in Exhibits 1, 2, and 3, the ABCDF Demil Facility located at the Edgewood Area of Aberdeen Proving Grounds had been treating mustard stored in ton containers with a hydrolysis reactor, in a process considered the prototypical approach planned for implementation at Pueblo Chemical Depot, designated the Pueblo Chemical Agent-Destruction Pilot Plant ("PCAPP"). The sampling data available from the ABCDF facility on the hydrolysate treatment residuals provided the first window into the actual composition of mustard. This data is attached to this rulemaking as Exhibits 4a and 4b. The Division's assessment of this data with respect to mustard characterization was presented to the Commission on August 15, 2009, and this PowerPoint presentation is attached to this rulemaking as Exhibit 5.

Previous Listing Determinations

In assessing the characterization that has been applied to munitions housing the chemical agent mustard with respect to the current listing, the assessments found in previous rulemakings (§ 8.30, § 8.46, and § 8.48) were evaluated in the light of the currently available information. EPA's assignment of the D003 characteristic is still operative. The Division finds that the toxicological profile presented for mustard in these previous rulemakings are entirely valid assessments and adequate to justify the retention of the P-listing for these wastes as an acutely toxic substance, the addition of the chemical agent mustard components HD and HT to the P-list at § 261.33 (e), the addition of mustard(s) to Appendix VIII of § 261 as a mutagens and carcinogens, the K-list at § 261.32 (a), and the addition of mustard(s) to Appendix VII of § 261. The P-listing is and has been typically applied to single component, off-specification chemicals. In these rulemakings, the K- listing for mustard contemplates the presence of other toxic constituents found in Appendix VII. Mustard is, in fact, no such single component material, and there are other chemicals that are needed in Appendix VII mustard listings besides the mustard(s) at concentrations of concern.

Contemporary Data and Revision of Listing Discussion

At the time of the previous rulemakings, the information known and available to the Commission did not include any definitive discussion regarding other constituents or characteristics exhibited by mustard. This was not an oversight, but it represented the extent of the available information and data. Since that time, the Division has closely scrutinized all available data and information pertaining to the composition of mustard.

During the previous rulemakings, no information was available regarding the corrosive nature of mustard, except its well known vesicant interactions with skin. It was known at that time that mustard was not an aqueous material, and that insufficient water was present in mustard to allow a determination of pH to forward an understanding of the potential that mustard may, or may not exhibit the D002 - characteristic of corrosivity, as defined in § 261.22 (a)(1). In the intervening time period since the original rulemaking, the Division has carefully evaluated the phenomena of leaking munitions that occur at PCD, along with the anecdotal information submitted in the MACR. The result of this analysis revealed three important findings:

(1) the physical process of leaking occurs as a result of pressurization of the agent cavity housing the mustard, and
(2) the propulsive force or pressurization of the agent cavity is, in fact, caused by the interaction of mustard with the steel of the agent cavity, a corrosive mechanism, and
(3) a penetration of the agent cavity must occur to allow the pressurized contents of the agent cavity to escape, and this weakened area of the agent cavity enclosure is caused by corrosion of the steel by mustard. Furthermore, data from the ABCDF facility conclusively show that mustard's reaction with water, while dubious for the copious generation of hydrogen chloride gas that may adversely affect human health, does generate sufficient dissolved hydrogen chloride gas in the form of hydrochloric acid to generate a pH less than the 2 standard units needed to exhibit the corrosive characteristic. Mustard is so toxic that sampling, handling, health, and safety issues preclude the execution of the definitive engineering test specified to elicit the corrosion to steel determination found at § 261.22 (a)(2). With the absence of test data, this is overwhelming evidence to conclude that mustard exhibits the characteristic of corrosivity, D002.

At the ABCDF facility, 8 percent by weight mustard agent was hydrolyzed with an excess of water in a reactor, and then pH adjusted to alkaline conditions (>12.5) to complete the reaction and eliminate the D003 characteristic. The inherently large dilution of the agent in water necessary to complete the reaction resulted in a treatment residual, or hydrolyzate that exhibits several characteristics. It is evident that the virgin mustard must either exhibit extraordinary concentrations of the compounds associated with these characteristics, or exhibits a propensity to generate these characteristics. The sampling of hydrolyzate can be conducted without the extreme risk associated with sampling virgin mustard, and the volumes of secondary wastes generated are inconsequential. These data represents the best data for understanding the composition of mustard. The accumulated ABCDF data support the conclusion that the following characteristics are applicable to mustard, and should be incorporated into the Treatment Standards for Hazardous Waste, § 268.40, and the following characteristics should be added to § 261, Appendix VII, Basis of Listing for mustard K listed wastes:

D002 Corrosive

D003 Water Reactive Subcategory

D004 D011 (Arsenic, Barium, Cadmium, Chromium, Lead, Mercury, Selenium, and Silver)

D027 1,4- Dichlorobenzene

D028 1,2 - Dichloroethane

D029 1,1 - Dichloroethylene

D039 Tetrachloroethylene

D040 Trichloroethylene

D042 2,4,6-Trichlorophenol

D043 Vinyl Chloride

Underlying Hazardous Constituents ("UHC") are those compounds present or reasonably expected to be present in characteristic waste at the point of generation. UHCs have their own treatment standards found in the Universal Treatment Standards Table at § 268.48. The accumulated ABCDF data support the conclusion that UHC chemicals are present in mustard and mustard treatment residuals. The variability of mustard within munitions is somewhat understood, but the presence and concentrations of residual production chemicals, by-products, congeners, and chemicals formed by the degradation of these substances cannot be well established with certainty. Therefore, a generally applicable list of chemicals with a reasonable probability of occurrence as UHCs related to mustard and mustard treatment residuals cannot be presently defined because their occurrence and concentration are inherently related not only to the parent mustard, but also to the precise treatment applied. Due to these uncertainties, most generators of hazardous waste must sample the hazardous waste, as generated, to determine UHCs, but mustard sampling cannot be entertained, or reasonably required without significant risk. The Army must sample treatment residuals to make this determination required by the Land Disposal Restrictions. The mix design (recipe), and operating variables (e.g., residence time, temperature, and pH) can alter the actual composition of a treatment residual; therefore, the applicable UHCs list associated with mustard is peculiar to the treatment process. The ABCDF facility UHC list was ascertained by sampling and analysis of the hydrolyzate, and if the PCAPP plant was operated identically, this list would be valid for PCAPP. If there are local variations, or colloquial initiatives at PCAPP, the ABCDF UHC list may not be applicable in its entirety, and sampling for UHCs would be necessary. It should be noted that the ABCDF hydrolyzate did not have to comply with Land Disposal Restriction oversight because this residual was treated in an exempt, permitted Clean Water Act unit (a large POTW). Some of the Underlying Hazardous Constituents found in mustard hydrolyzate from the ABCDF facility include the following:







Carbon Tetrachloride




Methylene Chloride





Ethylene Oxide



Ethyl Ether



Thus, it is acknowledged that the assignment of a list of applicable UHCs pertain only to the mustard and to treatment residuals generated by a specific process. If, as has already been discovered, a different and distinguishable process is used to decontaminate mustard, other characteristics may be exhibited which need to be added to the treatment residuals, and/or the UHC list modified to account for all of the chemicals found from sampling. Specifically, the mustard calibration standards used in the laboratory at PCD are treated by the addition of sodium hypochlorite to hexane containing known quantities of mustard. When this approach is used, Chloroform is synthesized as a disinfection by-product in the treatment residual, and depending upon the treatment recipe, mass loading, and operational controls, the residual may also exhibit the D022 characteristic for Chloroform. If Chloroform is present at a concentration less than the regulatory threshold for D022 at 6 ppm in a TCLP extract, it may be a UHC with its own treatment standard. Regarding these facts, it is clear that there is a distinct advantage to delineating these mustard waste forms, their associated codes, and the treatment standards that are applicable for the benefit of the Army, the Division, and the Commission.

Generators of Hazardous Waste are required to meet the applicable standards for UHCs for their characteristic hazardous waste, and if process knowledge is lacking, regarding the presence and concentrations of UHCs, sampling is required for the 250+ UHCs in the Universal Treatment Standards Table found at § 268.48. For each process applied to mustard, the mustard residuals must be sampled because the process knowledge with regard to UHCs is not fundamentally defined.

Land Disposal Restrictions applicable to Mustard and Mustard Waste Forms

This rulemaking incorporates the aforementioned mustard listing revisions into § 261.32(a) (Hazardous Waste from Specific Sources), into Appendix VII of Part 261 (Basis for Listing Hazardous Waste), and into § 268.40 (Treatment Standards for Hazardous Waste).

These amendments are more stringent than the federal regulations, which do not contain federal analogs to the state-only K901, K902, P909, and P910 mustard agent listings related to military munitions. The Commission finds that there is substantial evidence in the record that these rules are necessary to protect the public health and the environment of the state. The Commission's findings are based upon its evaluation of the public health and environmental information and studies contained in the rulemaking record, the Statement of Basis and Purpose, and testimony presented at the hearing. Pursuant to C.R.S. section 25-15-302(4)(a), these findings were approved by more than six members of the Commission.

Statement of Basis and Purpose - Rulemaking Hearing of February 16, 2010


6 CCR 1007-3-8.72
37 CR 24, December 25, 2014, effective 3/2/2015 38 CR 11, June 10, 2015, effective 6/30/2015 39 CR 05, March 10, 2016, effective 3/30/2016 39 CR 11, June 10, 2016, effective 6/30/2016 40 CR 06, March 25, 2017, effective 4/14/2017 40 CR 11, June 10, 2017, effective 6/30/2017 40 CR 21, November 10, 2017, effective 11/30/2017 41 CR 06, March 25, 2018, effective 4/14/2018 41 CR 11, June 10, 2018, effective 6/30/2018 41 CR 24, December 25, 2018, effective 1/14/2019 42 CR 06, March 25, 2019, effective 4/14/2019 42 CR 06, March 25, 2019, effective 5/30/2019 42 CR 11, June 10, 2019, effective 6/30/2019 43 CR 12, June 25, 2020, effective 7/15/2020 44 CR 06, March 25, 2021, effective 4/14/2021 44 CR 11, June 10, 2021, effective 6/30/2021 44 CR 24, December 25, 2021, effective 1/14/2022 45 CR 11, June 10, 2022, effective 6/30/2022 45 CR 17, September 10, 2022, effective 9/10/2022 45 CR 17, September 10, 2022, effective 9/30/2022 45 CR 23, December 10, 2022, effective 1/30/2023

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