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December 30, 2013
RCRA exclusion for sequestered CO2

A new EPA rule that excludes geologically stored CO2 from the definition of hazardous waste is part of a larger effort by the Agency to smooth the path for the implementation of carbon capture and sequestration (CCS). 

To qualify for the exemption, operators must meet certain conditions, including compliance with Department of Transportation (DOT)  regulations affecting the off-site movement of CO2 through pipelines.  The Obama administration is a strong advocate of CCS, which has been named by the EPA as the best system of emission reduction (BSER) in a separate proposal setting limits on CO2 emissions from new coal-fired power plants.

Solid waste

In the rule, the EPA emphasizes that CO2 in the supercritical state (i.e., possessing properties intermediate to those of gases and liquids), which the Agency believes is most appropriate for CCS injection, is a solid waste.  In contrast to CO2 that is used for enhanced oil/gas recovery (EOR/EGR)—the CO2 in such cases is a commodity, not a waste—CO2 that is sequestered underground for long periods of time is discarded.

Because of the differences, the EPA used its authority under the Safe Drinking Water Act (SDWA) to establish new regulations specifically for CCS.  This program provides for a separate SDWA Class VI underground injection control (UIC) permit for CCS to differentiate the activity from EOR/EGR, which requires a Class II UIC permit. 

Other adequate regulations

The Class VI regulations are generally more comprehensive than the protective measures required for Class II wells.  For example, Class VI wells must meet more stringent well integrity requirements and more extensive monitoring is required.  In addition, the EPA says the regulations imposed by DOT’s Pipeline and Hazardous Materials Safety Administration (PHMSA) for pipelines that transport CO2 off-site are protective of public safety.  Given these two sets of regulations, the EPA says it believes that injected CO2 can be exempted from RCRA’s hazardous waste definition even if hazardous substances are unintentionally present in the CO2 stream. 

“EPA’s longstanding regulatory criteria for determining whether wastes pose hazards that require regulatory control incorporate the idea that a waste that is otherwise hazardous may not present a hazard if already subject to adequate regulation,” says the Agency. 


Under the rule, the exclusion applies to CO2 streams that would otherwise be regulated as hazardous waste under RCRA Subtitle C provided four conditions are met: 

  • Transportation of the CO2 stream must be in compliance with applicable PHMSA requirements.
  • Injection of the CO2 stream must be in compliance with the applicable requirements for UIC Class VI wells.
  • No other hazardous wastes may be mixed with, or otherwise co-injected with, the CO2 stream.
  • Generators and UIC Class VI well owners or operators claiming the exclusion must sign a certification statement that the conditions of the exclusion were met.

If hazardous waste is mixed with the CO2 stream, that stream would not be eligible for the conditional exclusion.  Rather, that stream would need to be managed as a RCRA hazardous waste and, if well injection is selected as the means of disposal, injected into a UIC Class I hazardous well.
The EPA says the new rule reduces regulatory uncertainty that may impede the development of CCS.  The action is also consistent with one of the recommendations made by President Obama’s Interagency Task Force on CCS in August 2010, says the EPA.

The final rule

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