6 CCR 1007-3-8.80 - 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.

Addition of K903 (Hydrolysate) Listing


These proposed amendments create a new hazardous waste listing for mustard agent hydrolysate to accurately reflect its chemical hazard. Hydrolysate is the aqueous waste resulting from the chemical neutralization, or "hydrolysis," of Mustard Agent (K901) with the addition of copious amounts of water. Hydrolysate is a waste derived from the treatment of mustard agent that currently carries the existing K901 or K902 specific source hazardous waste listings for military munitions. Under the K901 or K902 hazardous waste listings for chemical weapons, any treatment residue of mustard agent, or any water contaminated through contact with mustard agent, is considered an acute hazardous waste (Hazard Code H), mandating restrictive regulatory requirements. The acute hazardous code associated with the military munitions waste listings is due to the presence of mustard agent, which is a carcinogen, mutagen and teratogen and capable of causing human health impacts at low concentrations. However, analytical characterization data as well as technical information for the mustard agent neutralization process that has recently become available indicates that once neutralized, and subsequently stabilized by increasing the pH of the derived waste to a sustained level greater than 10, hydrolysate waste no longer contains detectable concentrations of the agent. These amendments therefore propose to create a new listing for the hydrolysate waste, K903 that does not include the acute hazardous waste code. The new non-acute listing for this waste will allow for more regulatory flexibility in storage, treatment and management of the waste, and also ensure that the chemical hazard of the waste is properly designated during any subsequent transportation to a permitted treatment, storage or disposal facility.

Previous rulemakings for the K901 and K902 waste listings for mustard agent wastes (See 6 CCR 1007-3, § 8.46 and § 8.72) established the underlying basis for the listings which also include several other hazardous waste constituents in addition to mustard agent. These underlying hazardous waste constituents (UHCs) are present in the original agent due to manufacturing impurities or chemical degradation byproducts. While no mustard agent remains in the neutralized hydrolysate, the waste still retains diluted concentrations of UHCs that must be properly treated before the waste may ultimately be disposed of in a hazardous waste landfill. Additionally, the previous amendments to the K901 and K902 listings inadvertently included two hazardous waste constituents in the mustard agent waste that are not in it, and omitted two other constituents that are present in it at its point of generation. These amendments therefore also propose to add a land disposal restriction treatment standard for the K903 hydrolysate waste that retains Part 268 land disposal restriction treatment standards for all the UHCs present in the waste, including the two additional UHCs contained in it, to ensure it is properly treated prior to land disposal. The proposed amendments would also add the two additional constituents to the existing K901 and K902 listings in Part 268, and would remove the two inadvertently included constituents from the listings.

Specific Regulatory Amendments

The Colorado Department of Public Health and Environment, Hazardous Materials and Waste Management Division (the Division) is proposing the following amendments to 6 CCR 1007-3:

1) Addition of a hazardous waste listing, K903 for hydrolysate, defined as the waste generated from the chemical neutralization of Mustard Agent with water, to the list of hazardous waste in Section 261.32 - "Hazardous Waste from Specific Sources" - Military Munitions
2) Addition of Hydrolysate to Part 261 Appendix VII - "Basis of Listing Hazardous Waste" for proposed K903 listing
3) Addition of a treatment standard for K903 hydrolysate waste generated from mustard agent (HD and HT) contained in all three configurations of munitions, including 105mm, 155mm, and 4.2 inch mortars to Part 268.40 following the point in the neutralization process where the hydrolysate is manipulated to a sustained and stable pH of greater than 10,
4) Removal of two hazardous constituents from the basis for the K901 and K902 hazardous waste listings, 1,4-dichlorobenzene and 2,4,6-trichlorophenol, from Parts 261, Appendix VII, and 268.40 that are not present in the mustard agent and that should not have been included in the original listings.
5) Addition of two hazardous constituents to the basis for the K901 and K902 hazardous waste listings, chloroform and hexachloroethane, to Parts 261, Appendix VII, and 268.40 that are present in the mustard agent and that should also be included in the original listings.

Mustard Agent Neutralization and Chemical Analysis of Hydrolysate

The Department of Defense and U.S. Army are currently pursuing treatment and destruction of over 750,000 waste chemical weapons stored at the Pueblo Chemical Depot (PCD). The chemical weapons inventory is composed of 105mm and 155mm projectiles and 4.2 inch mortars that contain over 2600 tons of mustard agent (HD and HT). The Pueblo Chemical Agent-Destruction Pilot Plant (PCAPP) Facility is currently under construction at PCD and will be used to safely dismantle the weapons, access the mustard agent inside them, and treat the agent by neutralizing, or hydrolyzing, it with water. The resulting waste, or hydrolysate, will then be subsequently treated at PCAPP in biological treatment units to eliminate the primary breakdown product of the mustard hydrolysis reaction, thiodyglycol. Thiodyglycol is a schedule 2 chemical compound that must also be destroyed with the mustard agent in accordance with the international Chemical Weapons Convention. Once treated, the hydrolysate or water waste will be sent through a crystallizer and brine reduction system on-site to separate and remove metal salts, with the treated effluent then recycled back into the mustard neutralization process.

Mustard agent hydrolysis will occur in tank reactors at PCAPP and will be closely monitored to ensure for complete destruction of the mustard agent. Recently, treatability studies were completed at Battelle Laboratories in West Jefferson, Ohio on samples of the two different types of mustard agent found in the stockpile of weapons at PCD (HD and HT). The purpose of the treatability studies was to ensure that the planned recipe and parameters for treatment of the mustard will be effective in destroying the Pueblo agent and also to obtain a detailed chemical analysis of the resulting hydrolysate. Hydrolysis of the mustard agent was completed in the same manner it will be performed at PCAPP under the treatability studies, which essentially involves mixing the mustard agent rigorously with water at a ratio of 1:8, and then subsequently bringing up the pH of the mixture with sodium hydroxide to a sustained and stable pH greater than 10. Retention of the treated mixture at the sustained and stable pH greater than 10 is necessary to completely destroy breakdown products of the mustard agent, including sulfonium ions that can still cause blistering effects and that also may readily revert back into mustard agent.

The analytical results for the hydrolysate generated during the treatability studies demonstrated that the Pueblo agent will be successfully neutralized by hydrolysis. No detectable concentrations of mustard agent (HD or HT) were identified in either of the hydrolysates, indicating that both types of mustard agent will be completely destroyed. Detailed chemical analysis of the hydrolysates resulting from the treatability studies did however show detectable concentrations of several other hazardous waste constituents. While many of these constituents were diluted to very low concentrations with the water used in the hydrolysis process, a few of the constituents remained at concentrations above toxicity characteristic levels. Further analysis of these results indicates that none of the hazardous waste constituents remaining in the hydrolysate were present at levels which would cause the waste to be considered an acute hazardous waste in accordance with 6 CCR 1007-3, Section 261.11(a)(2).

Hydrolysate is a waste derived from the treatment of mustard agent that has been chemically altered to eliminate the mustard agent contained in it. The results of the treatability study therefore support listing of this hydrolysate waste with a new K903 listing that does not retain the acute hazard code, but retains the toxicity code in accordance with 6 CCR 1007-3, Section 261.11.

Regulatory Analysis

Creation of a new non-acute hazardous waste listing (K903) for mustard agent hydrolysate will allow for greater flexibility in managing this waste at PCAPP once it is neutralized and analytically verified to be free of agent downstream of the hydrolysis reactors. In particular, the new non-acute listing for hydrolysate will allow larger volumes of any newly generated wastes that may come in contact with the hydrolysate to also be managed as non-acute hazardous waste. This flexibility is significant in that up to 55 gallons of non-acute waste may be accumulated in a satellite accumulation area before it must be removed, whereas acute hazardous waste may only be accumulated up to one quart in a satellite area before it must be removed. Triple rinsing of containers holding hydrolysate wastes will not be required under the new waste listing because they will not be considered acute. Finally, the new listing would also ensure that the correct hazard code is reflected on the manifest for the waste in the event an accident occurs during transport.

In accordance with 6 CCR 1007-3, Section 268.3(a), the dilution prohibition states that a hazardous waste cannot be diluted in any way as a substitute for adequate treatment to achieve compliance with the land disposal restriction standards. Accordingly, the basis for hydrolysate listing and the new treatment standard for it ensure that all the hazardous waste constituents originally present in the mustard will be properly treated prior to land disposal. Mustard hydrolysate is not a newly generated waste, but rather a mustard agent waste that has been chemically altered to destroy the agent. While effective in destroying the mustard agent, the hydrolysis process is not effective at treating all the underlying hazardous waste constituents that were originally present in the waste mustard. Since UHCs in the mustard largely become diluted in the hydrolysate, retention of the hydrolysate as a hazardous waste subject to treatment requirements for any UHCs contained in it will ensure the dilution prohibition for this waste is not violated.

Impact of Proposed Listing and Treatment Standard

A new non-acute mustard hydrolysate listing will allow for more regulatory flexibility in managing this waste which no longer contains mustard agent. Currently, the only facility in Colorado known to possess large quantities of mustard agent is PCD and the only facility that may generate large quantities of mustard hydrolysate is PCAPP. Site-wide clean-up of the Rocky Mountain Arsenal is near complete and future management of any mustard agent or hydrolysate at RMA is not expected. PCD is owned and operated by the United States Army, which also is an owner of PCAPP with the Department of Defense. Small quantities of mustard agent may be discovered at other former military training facilities in the future, but it is not likely that large quantities of agent will be found. In the event mustard agent is neutralized during such a discovery, and mustard hydrolysate is generated in accordance with the new hydrolysate listing, these other military facilities may utilize the flexibility created by the new hydrolysate listing. Finally, in the event the mustard agent hydrolysate cannot be successfully treated at PCAPP, the waste may be shipped off-site to another permitted hazardous waste treatment, storage or disposal facility that may also manage the waste in accordance with the new hydrolysate listing.

Commission Finding

The Commission has evaluated the information presented at the rulemaking hearing, as well as the information in the Statement of Basis and Purpose. The Commission finds that this rule is necessary to protect the public health and the environment of the state.

Statement of Basis and Purpose - Rulemaking Hearing of February 19, 2013


6 CCR 1007-3-8.80
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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