UNITED STATES ENV I RONMENTAL PROTECTION AGENCY WASHINGTON , D

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### APR 

### 2 3 2015

OFFICE O F WA I ER MEM O RA ND UM FROM: Peter C. Grevatt, D i r ecto r Office of Ground Water and Drinkin g Water TO: Reg ion a l Water Di v ision Directo rs SUBJEC T : Key Prin ci ples i n EPA's Undergrotmd In jection Cont ro l Prog ram C lass V I Rul e Re lated to Tran s i tion of Class II Enhanced Oil or Ga s Recove ry W e lls to C la ss VI
Most s tates hav e primary enforcement re s ponsibility ( i .e., prim acy) for the C l ass II Underground Inj ection Co ntrol program fo r o il or gas -re lated injection act iv iti es , whi le EPA R egions c urre ntl y retain direc t impl e mentat ion authority fo r th e C lass VI program in eve ry sta le. The shared impl e me nt ation of t he U IC program neces s itates a clear arti culati on and co mm o n understanding of th e p o te ntial for tran s ition of enhanced r ecovery wells from C las s II to C lass V I , consistent w ith EPA's C las s VI Rul e . Thi s memo is intended to e mph asize the key prin c i ples in EPA ' s UI C C lass VI Rul e re lat e d to th e tran si tion from C la ss II to C lass VI for ER wells that inj ec t carbon dioxide for l ong -term s torage. As Regions work w ith states on impl e me ntati on of th e Cla s s VI program , I e nc o ura ge y ou to assist s tates in s ubmittin g primacy app li cat io n s for a ll we ll classes , in c ludin g Class VI. E PA recognizes the imp o rtan ce of geo lo gic sequestrati o n of anthrop oge ni c C02 for clim ate c hange m it i g ation. The U IC C lass V I Rul e was deve lop ed to facilitate GS and e n s ure pro tec tion of und erg ro und sources of d r inking water from the p a 11icul ar risks that large sca le C02 inj ect ion for purposes of lon gtenn s tora ge may pose . The fo llowin g are key principles rela t ed to the transition of ER we ll s that store C0 2 from C lass 11 operations to the C lass Vl program: 1. 

### Geo log ic s t o r age of C02 c a n co n t inu e to be p ermitte d und er th e UI C C lass II prog r a m. ER we ll s across tbe U. S. are c urrent ly pe rmitte d as UIC C lass II we ll s . C02 storage as soc iated with C la ss II we ll s is a common occ urrence, and C0 2 can be s afel y stored w he r e inj ected through C lass II -p ermitted we ll s for the purpose o f o il o r gas-related r ecovery . 

### 2. Use of a n th r o poge ni c C 0 2 in E R o p er ati on s d oes n ot necess it ate a C l ass VI p ermit
. ER operat io n s can c o ntinu e to be p e rmitt ed as C l ass II we ll s , regard less of the source of C 0 2
. An owner or operator of an ER operation can sw itch from u s ing a natur a l source to an anthropogenic source of C 0 2 wi thout tri gger in g th e ne ed fo r a C lass V I permit.

lnterne1 Address ( URU · http // wwwepa gov Recycled/ Recyclable · Printed w11h Vegetable 011 Ba s ed Inks on 100 % Posiconsumer Process Chlonne Free Recycled Paper**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**  **202-564-38**

### 2 **3 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 111** **/ieu tllere**  **is au**  **increased risk**  **to USDWs**  **compared to**  **Class II**  **operations.**