May 17, 2021

POLYM: Lots of Questions, Few Answers

Polymerization is a chemical reaction where often-ignitable mixtures of resins and catalysts are turned into an inert durable solid material. In the land disposal restrictions (LDR) program, polymerization (POLYM) is also one of three methods that may be used for treating high-total organic carbon (TOC) ignitable liquids (including unwanted or “scrap” resins) to meet their §268.40 LDR treatment standards. The LDR definition of POLYM is “[f]ormation of complex high-molecular weight solids through polymerization of monomers in high-TOC D001 non-wastewaters which are chemical components in the manufacture of plastics.” [§268.42] EPA’s guidance in RO 14938 provides some hints on whether POLYM is thermal treatment requiring a permit and if closing a container undergoing POLYM treatment with an unsecured lid is appropriate for meeting Subpart CC standards.

Thermal treatment

Treatment in a 90/180/270-day accumulation unit, such as a container or tank, without a RCRA permit is allowed, albeit with some exceptions. In 1997, EPA stated POLYM could be performed at the site of generation in one of these accumulation units without a permit. [62 FR 26008] However, the agency has also said thermal treatment in one of these units is not allowed. [RO 14662] POLYM often requires indirect heating to increase the temperature of the resin/catalyst mixture to activate the catalyst. The underlying issue is whether such indirect heating is considered “thermal treatment.” Section 260.10 defines thermal treatment as:

“[T]he treatment of hazardous waste in a device which uses elevated temperatures as the primary means to change the chemical, physical, or biological character or composition of the hazardous waste….”

According to the American Composites Manufacturers Association (ACMA), some state regulatory agencies have determined that application of indirect heat to scrap resin when conducting POLYM is thermal treatment. Thus, ACMA specifically asked EPA to provide national guidance stating indirect heating associated with POLYM does not meet the definition of thermal treatment and, thus, is allowed in an onsite generator accumulation unit without a RCRA permit.

EPA did not provide the requested guidance, but only noted it is “best to continue to rely on regional and state inspectors ‘on the ground’ since they have a fuller picture of a given facility’s entire process, allowing them to make appropriate determinations on a case-by-case basis.” There was one reference in RO 14938 that had to do with treatment: “Polymerization as a waste treatment method could, in some instances, meet the definition of a waste stabilization process, as defined in §265.1081.... If so, and if the polymerization occurs in containers with a design capacity of greater than 26.4 gallons, then the generator treatment containers would be subject to the Container Level 3 standards under Subpart CC (see §265.1087(b)(2)).”

Closed containers

RCRA regulations generally require a hazardous waste container to remain closed, except when adding or removing waste. [§§262.16(b)(2)(iii)(A), 262.17(a)(1)(iv)(A)] Additionally, the Subpart CC air emission standards generally require 90-day accumulation containers at LQGs to be equipped with closure devices ensuring there are no visible holes, gaps, or other open spaces. [§265.1087(c)(1)(ii)] However, POLYM is an exothermic reaction, generating heat and gases. Industry experience with POLYM shows lids equipped with pressure-relief valves are inadequate to prevent drum bulging or rupturing. Thus, ACMA specifically asked EPA to provide national guidance stating hazardous waste containers with an unsecured lid or alternative covering (i.e., with no visible opening) in which POLYM is occurring meets Subpart CC standards. EPA did not provide the requested guidance but, again, deferred to regional and state personnel determinations.


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This document addresses issues of a general nature related to the federal RCRA regulations. Persons evaluating specific circumstances dealing with the RCRA regulations should review state and local laws and regulations, which may be more stringent than federal requirements. In addition, the assistance of a qualified professional should be enlisted to address any site-specific circumstances.