UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

APR 2 3 2015 

OFFICE OF WA IER 

MEMORANDUM 

FROM: 	 Peter C. Grevatt, Director 

Office of Ground Water and Drinking Water 

TO: 	 Regional Water Division Directors 

SUBJECT: 	 Key Principles in EPA's Undergrotmd Injection Control Program Class VI Rule 

Related to Transition of Class II Enhanced Oil or Gas Recove ry Wells to Class VI 

Most states have primary enforcement responsibility (i.e., primacy) for the Class II Underground 

Injection Control program for oil or gas-related injection activities, while EPA Regions currently retain 

direct implementation authority for the Class VI program in every stale. The shared implementation of 

the UIC program necessitates a clear articulation and common understanding of the potential for 

transition of enhanced recovery wells from Class II to Class VI, consistent with EPA's Class VI Rule. 

This memo is intended to emphasize the key principles in EPA's UIC Class VI Rule related to the 

transition from Class II to Class VI for ER wells that inject carbon dioxide for long-term storage. As 

Regions work with states on implementation ofthe Class VI program, I encourage you to assist states in 

submitting primacy applications for all well classes, including Class VI. 

EPA recognizes the importance of geologic sequestration of anthropogenic C02 for climate change 

mitigation. The UIC Class VI Rule was developed to facilitate GS and ensure protection of underground 

sources of drinking water from the pa11icular risks that large scale C02 injection for purposes of longtenn storage may pose. The following are key principles related to the transition ofER wells that store 

C02 from Class 11 operations to the Class Vl program: 

1. Geologic storage of C02 can continue to be permitted under the UIC Class II program. 

ER wells across tbe U.S. are currently permitted as UIC Class II wells. C02 storage associated 

with Class II wells is a common occurrence, and C02 can be safely stored where injected 

through Class II-permitted wells for the purpose of oil or gas-related recovery. 

2. Use of anthropogenic C0 2 in ER operations does not necessitate a Class VI permit. 

ER operations can continue to be permitted as Class II wells, regardless of the source ofC0 2. An 

owner or operator of an ER operation can switch from using a natural source to an anthropogenic 

source ofC0 2 without triggering the need for a Class VI permit. 

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3. Class VI site closure requirements are not required for Class II C02 injection operations. 

A Class II well that has been used for injection of anthropogenic or non-anthropogenic C02 and 

has been operated within its permit conditions can be closed as a Class lI well. 

4.	ƒ ER operations that are focused on oil or gas production will be managed under the Class II 

program. If oil or gas recovery is no longer a significant aspect of a Class n permitted ER 

operation, the key factor in determining the potential need to transition a C02 ER 

operation from Class II to Class VI is the increased risk to USDWs related to significant 

storage of C02 in the reservoir, where tbe regulatory tools of the Class II program cannot 

successfully manage the risk. 

The most direct indicator of increased risk to USDWs is increased pressure in the injection zone 

related to the significant storage of C02. Increases in pressure with the potential to impact 

USDWs should first be addressed using tools within the Class II program. Transition to Class VI 

should only be considered if the Class II tools are insufficient to manage the increased risk. 1 

S. The Class II and Class VI directors should work together to address the potential need for 

transition of any individual operation from a Class II to a Class VI permit. 

The Class II program director (in most cases a state official) will have the relevant data on 

pressure and volume of C02 injected into Class II ER operations, which will influence any 

transition decision. EPA encourages the Class II director to contact the Class VI director where 

he/she believes the risk has changed as a result of significant storage of C02 in the reservoir. 

6.	' The best implementation approach is for states to administer both the Class II and the 

Class VI UIC programs. 

EPA encourages states to apply for primacy for all well classes, including Class VI. Based on our 

conversations with states, in most cases, states who are approved for primacy for the Class VI 

program are expected to administer the program through their oil and gas program. 

The Office of Ground Water and Drinking Water is currently working with the U.S. Department of 

Energy, state associations, EPA Regions and stakeholders to finalize technical guidance focused on risk 

factors discussed in the Class VI Rule at 40 CFR 144.19. As we complete the final guidance, we will 

work to ensure that these key principles remain clear. 

Please contact me or have your staff contact Ron Bergman at 202-564-3823 if we can be of assistance to 

you on these or other UIC program issues. 

1 The key regulation, "Transitioning rrom Class 11 to Class VI," codified at 40 CFR 144.19, states that owners or operators 

that are injecting carbon di ox idc for tile primary purpose of /oug-term storage into an oi I and gas reservoir must apply for 

and obtain a Class VI GS permit 11

/ieu tllere is au increased risk to USDWs compared to Class II operations.