This comment letter response contains two parts:   

(1) The original submittal from the commenter.

(2) A data base printout of EPA’s response to each point raised by the commenter.

Notes about the response letters:

• The response letters were generated by a data base used to track the content of all public

comment submittals and ensure that the Agency responds to each. Each comment letter

was assigned a Letter ID that corresponds to the last four digits of the docket number of the

original comment (as posted on www.regulations.gov).

• Each response letter includes: comment text; an EPA‐assigned comment code; and an

individual response. These are described and explained below.  

• The data base contains Comment text from the letters submitted by commenters.  

Many hard copy letters were scanned into electronic format for inclusion in the data

base. As a result, there may be some typographical errors attributable to optical

character recognition issues.  However, all original submittals were reviewed in the

process of drafting responses to ensure that the comment content was understood and

appropriately addressed.

• The content of each comment letter was divided into topic areas and assigned a unique

Comment ID.  Additionally, one or more Comment Codes (i.e., unique topic area ID) was

assigned to each discrete point raised by a commenter. This information was added to

the data base. To inform final rulemaking decisions, all comments and information

received on a given topic were reviewed by technical experts in each rule area (e.g., on

construction requirements).  

• Following decisions on the final rule requirements, Individual responses were drafted

by topic area to ensure completeness and consistency of the responses with the final

rule and other responses to similar comments.  Each discrete point made by a

commenter was given a unique response.

• Upon completion of comment responses, all information was entered into the data base.

Each letter response is a compilation of each comment and its individual response,

compiled in the order of the original comment letter.  As a result of this process, there is

repetition in the response text.  The Agency believes this approach ensures completeness

and attention to each comment letter that was submitted.   

• All comments in a topic area were reviewed, evaluated, and responded to concurrently.  

Responses on each topic area are compiled and are also available in the rulemaking docket.
COMMENTS OF THE INTERSTATE OIL AND GAS COMPACT COMMISSION 

ON THE 

U.S . ENVIRONMENTAL PROTECTION AGENCY'S 

PROPOSED FEDERAL REQUIREMENTS UNDER THE UNDERGROUND 

INJECTION CONTROL PROGRAM FOR CARBON DIOXIDE GEOLOGIC 

SEQUESTRATION WELLS 

DOCKET ID NO. EPA-HQ-OW-2008-0390 

December 23, 2005 

~::-r DEC 2 3 2008 

The Interstate Oil and Gas Compact Commission, representing the U.S . states that 

produce oil and natural gas, submits the following comments to Docket ID No . EPA-HQOW-2008-0390 on the Environmental Protection Agency's Proposed Federal 

Requirements for Carbon Dioxide (COZ) Geologic Sequestration (GS) Wells under the 

Underground Injection Control (UIC) Program of the Safe Drinking Water Act (SWDA). 

1 . General Comments 

A. Funding: It is essential that EPA provide adequate funding to states assuming 

primacy jurisdiction under the UIC program to administer C02 storage 

regulatory activities . 

2. IOGCC Response to EPA Narrative Proposal 

II . C. Who Implements the UIC Program? 

A. EPA seeks comment on any aspects of the ongoing State efforts to 

regulate the GS of COZ and how these efforts might be used to better 

inform a final Federal rulemaking. 

IOGCC Response: Many states currently have primacy jurisdiction under 

the UIC program and administer Class II and other wells. Primacy should 

be allowed for Class VI and should be structured to allow flexibility in the 

primacy process and defer to the state rule where it effectively meets the 

intent of the federal requirements. 

II . G. How Would This Proposal Affect Existing Injection Wells Under the UIC 

Program? 

DEC 2 3 2008 
B. EPA seeks comment on the merits of this approach since owners or 

operators of some Class II EOR/EGR wells may wish to use wells for 

the purposes of production and GS prior to the field being completely 

depleted . 

IOGCC Response: The IOGCC agrees with EPA's proposed approach as 

long as the project is an EOR project under Class II and the operator has 

been able to demonstrate viable production. EPA should consider a 

separate classification other than the proposed Class VI, as well as 

requisite requirements, for wells that are transitioned from Class 11 EOR to 

Class II related storage. 

11 . G. How Would This Proposal Affect Existing Injection Wells Under the UIC 

Program? 

C. EPA is proposing to give the Director discretion to carry over or 

"grandfather" the construction requirements (e.g ., permanent, 

cemented well components) for existing Class I and Class II wells 

seeking a permit for GS of CO2, provided he/she is able to make a 

determination that these wells would not endanger USDWs. 

IOGCC Response: The IOGCC agrees that discretion is appropriate and 

necessary when reviewing other UIC class wells for use as UIC Class VI 

wells or another class of well as suggested in the response to II . G (B) 

above. 

II . G. How Would This Proposal Affect Existing Injection Wells Under the UIC 

Program? 

D. Accordingly, EPA is proposing that the Director have the discretion to 

"grandfather" the construction requirements for Class V experimental 

wells when they are converted to full-scale GS Class VI wells. As with 

converted Class I and Class II wells, these grandfathered wells would 

be required to meet the other requirements of today's proposed rule 

(e.g ., operating, monitoring, MIT, well plugging, post-injection site 

care and site closure). 

IOGCC Response: The IOGCC agrees that discretion is appropriate and 

necessary when reviewing other UIC class wells for use as UIC Class VI 

wells or another class of well as suggested in the response to II . G (B) 

above. 

11 . G. How Would This Proposal Affect Existing Injection Wells Under the UIC 

Program? 
E. EPA seeks comment on the approach to grandfather construction 

requirements at the Director's discretion for existing Class I, Class II, 

and Class V wells seeking to convert to Class VI wells, and whether 

additional construction requirements would be necessary to prevent 

endangerment to USDWs from the GS of CO2. 

IOGCC Response: As part of the primacy package negotiated with the 

state, when an operator submits an application to reclassify any existing 

injection well to Class VI or other storage well classification, the Director 

should have the flexibility to determine whether the well meets the federal 

Class VI or another storage well classification which incorporates 

protective standards and requires the operator to adhere to the permitting 

process . 

II . G. How Would This Proposal Affect Existing Injection Wells Under the UIC 

Program? 

F. Additionally, EPA seeks comment on how the grandfathering 

approach for existing wells may affect compliance with the 

requirements in this proposal. 

IOGCC Response: As part of the primacy package negotiated with the 

state, when an operator submits an application to reclassify any existing 

injection well to Class VI or other storage well classification, the Director 

should have the flexibility to determine whether the well meets the federal 

Class VI or another storage well classification which incorporates 

protective standards and requires the operator to adhere to the permitting 

process. 

II . H. What Are the Target Geologic Formations for GS of COZ? 

G. As with unmineable coal seams, EPA seeks comment on prohibiting 

injection into such formations if they are above the lowermost USDW. 

IOGCC Response: There should be no blanket prohibition against 

injection into any approved geologic zone even if above the lowermost 

USDW. There may be circumstances where this is perfectly appropriate 

and safe. The decision needs to be site-specific and based on evaluation of 

local geology. 

II . I. Is Injected COZ Considered a Hazardous Waste Under RCRA? 

H. EPA seeks comment on this approach and other considerations 

associated with the presence of impurities in the COZ stream . 
IOGCC Response: Injected COZ is not and should not be considered a 

hazardous waste or regulated under RCRA or CERCLA. It is assumed 

that RCRA or CERCLA wastes would be removed from the COZ stream 

prior to storage. 

Il . J. Is Injected COZ Considered a Hazardous Substance Under CERCLA? 

1. EPA requests comment on particular situations where this might occur. 

EPA also requests comment on other considerations associated with 

the presence of impurities in the C02 stream related to CERCLA. 

IOGCC Response: Injected COZ is not and should not be considered a 

hazardous waste or regulated under RCRA or CERCLA. It is assumed 

that RCRA or CERCLA wastes would be removed from the COZ stream 

prior to storage. 

III . Proposed Regulatory Alternatives 

J. EPA is proposing Regulatory Alternative 3, the Tailored Requirements 

Approach. EPA did not select alternative 1 (Non-Specific 

Requirements Approach) because it does not provide enough 

specificity to ensure that permitting authorities manage GS wells 

appropriately to prevent endangerment of USDWs. In addition, this 

alternative may be burdensome for owners or operators because of the 

potential for inconsistency across States and burdensome for 

permitting authorities who will likely be faced with developing their 

own technical approaches to regulating GS. 

IOGCC Response: The IOGCC strongly believes that Alternative lI is the 

better approach with some additional strengthening. This would allow 

necessary discretion and flexibility on the part of the Director . The 

alternative proposed by EPA, Alternative III, although described as 

"giving permitting authorities discretion in how to permit certain 

elements" appears to offer very limited discretion and flexibility to the 

Director. Alternative III is unnecessarily prescriptive. 

III A. 1 Proposed Geologic Siting Requirements 

K. EPA specifically seeks comment on the merits of identifying these 

additional zones. 

IOGCC Response: Secondary confinement should not be a requirement. 

Such a requirement would eliminate good and sound storage sites and 

reduce ultimate capacity of the country to store anthropogenic CO2. The 

determination as to whether secondary confinement should be required 

should be made on a project by project basis and be site specific. It is 
possible to hypothesize a circumstance where secondary confinement is 

not necessary with the addition of stronger monitoring requirements. 

III A. 2 Proposed Area of Review and Corrective Action Requirements 

IOGCC General Comment for Section lIl. A. 2: The IOGCC believes use 

of traditional well specific AoR is problematic for comprehensive site 

characterization and licensing. The IOGCC has recommended in its report 

a site characterization and licensing process that includes elements such as 

geologic and engineering evaluation, modeling, amalgamation of property 

rights and other appropriate elements that we believe exceeds the capacity 

of the traditional AoR to accomplish. 

III A. 2 Proposed Area of Review and Corrective Action Requirements 

L. EPA seeks comment on the use of modeling for AoR delineation. 

IOGCC Response: See General Comment for Section III. A. 2 above. 

The collection of physical data (i .e. well bore data) may be necessary to 

fully utilize modeling to determine the ultimate extent of the proposed 

COZ storage volume. Models should only be used when they are 

appropriate. The Director needs the flexibility to be able to supplement or 

substitute other data elements as appropriate. 

III A. 2 Proposed Area of Review and Corrective Action Requirements 

M. EPA seeks comment on allowing the use of proprietary models for GS 

sites. 

IOGCC Response: Proprietary models should be allowed provided the 

Director has discretion to evaluate the accuracy of the modeling 

methodology. It should be noted that confidentiality of proprietary models 

will be subject to statutory limitation in various jurisdictions. 

III A. 2 Proposed Area of Review and Corrective Action Requirements 

N. EPA seeks comment on the applicability of computational fluid flow 

models for delineating the AoR of GS sites. 

IOGCC Response: See General Comment for Section III. A. 2 above. 

The collection of physical data (i .e. well bore data) may be necessary to 

fully utilize modeling to determine the ultimate extent of the proposed 

C02 storage volume. Models should only be used when they are 

appropriate. The regulator of a GS project should not be required to rely 
fully on models. As noted above, states need the flexibility to be able to 

go beyond models. 

III A. 2 Proposed Area of Review and Corrective Action Requirements 

O. EPA seeks comment on requiring the reevaluation of the site AoR on a 

periodic basis, under what conditions the AoR should be reevaluated, 

and the appropriateness of a 10 year minimum fixed frequency for 

AoR reevaluation . 

IOGCC Response: Note: This comment is based on the traditional AoR 

requirement. Most states do an annual project review with the operator 

not only to evaluate the project's performance but to determine if 

additional measures are needed. Setting a frequency should be 

performance based and should be left to the Director's discretion, but in 

no event less than every two years. Only if the review determines that 

remodeling, further study or additional down-hole monitoring is 

necessary, should such work be done. Additionally, such additional work 

should be done as needed, not at a set time interval . 

III A. 2 Proposed Area of Review and Corrective Action Requirements 

P. EPA invites public comment on the merits and frequency of 

reevaluation of the AoR as well as the phased corrective action 

approach for GS wells. 

IOGCC Response: Same as the two comments above, however, the 

IOGCC reiterates the inappropriateness of using a wellbore-focused AoR 

methodology for evaluating the entire project. 

III A. 3 Proposed Injection Well Construction Requirements 

Q. EPA seeks comment on the proposed GS well requirements for depth 

of surface casing, the cementing of long-string casing, and 

construction with a packer set opposite a cemented interval. 

IOGCC Response: IOGCC agrees with the need for adequate protection 

of USDWs and the proposed measures. However, Director discretion is 

necessary to address site-specific conditions. Well construction should be 

evaluated so as to insure necessary protections of the USDWs, and should 

not be overly prescriptive . 

III A. 3 Proposed Injection Well Construction Requirements 
R. EPA also seeks comment on how the proposed grandfathering 

provisions for existing wells (construction requirements) may affect 

compliance with the above, proposed construction requirements. 

IOGCC Response: The IOGCC believes that Director discretion is 

appropriate and necessary when reviewing other UIC Class wells for use 

as UIC Class VI wells. Overly prescriptive well construction 

requirements will limit the use of existing UIC wells and possible 

sequestration zones. 

III A. 3 Proposed Injection Well Construction Requirements 

S. EPA seeks comment on the merits of horizontal well drilling 

techniques for GS wells and the applicability of well construction 

requirements discussed in this proposal. 

IOGCC Response: With Director discretion horizontal well drilling 

techniques may be appropriate for GS application. 

III A. 3 Proposed Injection Well Construction Requirements 

T. EPA seeks comment regarding requirements for degradation-resistant 

well construction materials, such as acid-resistant cements and 

corrosion resistant casing . 

IOGCC Response: Concerning degradation-resistant well construction 

materials, the EPA rule should not be overly prescriptive but instead set a 

performance standard that would allow on a case by case basis the 

cementing materials necessary to meet the standard . 

III A. 4 Proposed Injection Well Operating Requirements 

U. EPA is requesting comment on the extent and scope to which 

hydraulic fracturing should be allowed during GS injection, and 

whether the use of fracturing for the purposes of well stimulation is 

appropriate. 

IOGCC Response: While hydraulic fracturing may be necessary in some 

cases to complete an injection well, it should not be allowed during GS 

injection. Any fracturing during well completion stimulation should be 

engineered so as to eliminate any risk of damage to confining zones. 

III A. 4 Proposed Injection Well Operating Requirements 
V. EPA is also requesting information to better qualify the use of 

fracturing for GS injection in specific geologic settings and rock 

formation lithologies. 

IOGCC Response: As indicated above, hydraulic fracturing should only 

be allowed during the initial completion or recompletion of a well to 

enhance reservoir permeability. However, once the completion phase has 

ended and the operational or injection phase has begun, fracturing during 

injection should never be permitted. It is important to keep separate the 

concept of operational injection pressure limits and episodic well 

stimulation activities . 

In this respect, there should be no injection above the allowable permitted 

pressure . Additionally, hydraulic fracturing of the cap rock should never 

be allowed nor should pressure testing of the confining layer. 

III A. 4 Proposed Injection Well Operating Requirements 

W. EPA seeks comment on the merits of requiring down-hole shut-off 

valves in GS wells. 

IOGCC Response: There should be no hard and fast requirement for a 

down-hole shut-off valve in a GS well. Down-hole shut-off valves may, 

however, at Director discretion provide a necessary extra level of 

protection in more sensitive settings . 

III A. 4 Proposed Injection Well Operating Requirements 

X. As a result, the Agency is considering and requesting comment on 

alternative approaches that would allow injection between and/or 

above the lowermost USDW, and thus potentially allow for more areas 

to be available for GS while preventing USDW endangerment. 

IOGCC Response: There should be no blanket prohibition against 

injection into a zone even if above the lowermost USDW. There may be 

circumstances where it is perfectly appropriate and safe . The decision 

needs to be site specific based on local geologic conditions. 

III A. 4 Proposed Injection Well Operating Requirements 

Y. In summary, EPA is soliciting comment on whether COZ injection 

should be allowed into an injection zone above the lowermost USDW, 

when the Director determines that geologic conditions (e.g ., thousands 

of feet of intervening formations between the injection zone and the 

overlying and/or underlying USDWs) exist that will prevent fluid 

movement into adjacent USDWs. 
IOGCC Response: Injection criteria on which zones to use should be site 

specific based on local geologic conditions. 

III A. 4 Proposed Injection Well Operating Requirements 

Z. EPA is also requesting comments on whether aquifer exemptions 

should be allowed for the purpose of Class VI injection, and under 

what conditions should such aquifer exemptions be approved. 

IOGCC Response : Aquifer exemptions under Class VI should be allowed 

on the same basis as for other classes. Each exemption should be 

considered on its own merits based on local geologic conditions and the 

likelihood of use of the zone for future public water supply . 

III A. 4 Proposed Injection Well Operating Requirements 

AA. Finally, EPA seeks comment on whether the Agency should set a 

minimum injection depth requirement for COZ GS, rather than require 

that such injection take place below the lowermost USDW. 

IOGCC Response: EPA should not set a minimum injection depth 

requirement for COZ GS as it is unnecessary. The rule needs to allow site 

specific flexibility. 

III A. 4 Proposed Injection Well Operating Requirements 

BB . EPA seeks comment on the use of tracers in COZ GS operations, 

and any potential impact of tracers on human health or ecosystems as 

they relate to USDWs. 

IOGCC Response: Adequate down hole monitoring above the 

containment zone should in most cases eliminate the need for tracer 

systems to detect the presence of injected COz at the surface. Use of such 

tracers should not be required although should be an optional methodology 

for use at Director discretion. 

III A. 5 Proposed Mechanical Integrity Testing Requirements 

CC. EPA requests comment on the practicability of this requirement. 

IOGCC Response: The IOGCC believes that the methodologies and 

requirements under Class II would be sufficient for Class VI wells and that 

applying Class I requirements is too stringent. 

III A. 5 Proposed Mechanical Integrity Testing Requirements 
DD. EPA seeks comment on the appropriate frequency of internal and 

external MITs for GS injection wells, the appropriate types of MITs, 

and how to optimize MIT methods for GS . 

IOGCC Response: For internal MITs for GS injection wells, 5 years 

would be a sufficient frequency. For external MITs, the frequency should 

generally be annual depending upon the specific circumstances. The types 

of test should be those which are most appropriate under the specific 

circumstances. 

III A. 6 Proposed Plume and Pressure Front Monitoring Requirements 

EE. EPA seeks comment on the requirement for monitoring of GS sites 

for the purpose of tracking the location of the COZ plume and 

associated pressure front over time. 

IOGCC Response: The IOGCC suggests that the operator be required to 

conduct ongoing monitoring . The frequency of reporting to the regulatory 

agency should be flexible depending upon site characteristics . 

III A. 6 Proposed Plume and Pressure Front Monitoring Requirements 

FF. EPA seeks comment on the use and frequency of pressure fall-off 

testing for GS wells. 

IOGCC Response: The IOGCC does not see the necessity of pressure falloff testing for GS wells. It should be used as necessary but not mandated. 

III A. 6 Proposed Plume and Pressure Front Monitoring Requirements 

GG . Based on information evaluated to date, EPA believes that tracking 

the plume and pressure front is an important companion step to 

address any uncertainties associated with initial AoR modeling and 

requests comment on this approach and more efficient alternatives that 

may be used to track the plume and pressure front. 

IOGCC Response: Tracking of the COz plume and pressure front should 

be required . The methodology, however, should not be specified but 

determined on a site specific basis. The IOGCC agrees with the following 

EPA statement : "As such, allowing flexibility in choosing the plume 

tracking methods and other monitoring technologies may provide an 

appropriate balance between the protective nature of indirect monitoring 

and cost considerations, as well as allowing for the adoption of 

continuously advancing technology." 

III A. 6 Proposed Plume and Pressure Front Monitoring Requirements 
HH. EPA seeks comment on the appropriate amount and types of 

monitoring that should be conducted at a GS site . 

IOGCC Response: The IOGCC agrees that owners and operators should 

report semi-annually on the characteristics of injection fluids, injection 

pressure, flow rate, temperature, volume and annular pressure, and on the 

results of MITs, ground water monitoring, and any required 

atmospheric/soil gas monitoring . The amount and types of monitoring to 

be required, however, should be site specific . 

III A. 6 Proposed Plume and Pressure Front Monitoring Requirements 

11 . Specifically, EPA seeks comment regarding the usefulness of indirect 

geophysical monitoring and surface air and soil gas monitoring. 

IOGCC Response: The IOGCC agrees that owners and operators should 

report semi-annually on the characteristics of injection fluids, injection 

pressure, flow rate, temperature, volume and annular pressure, and on the 

results of MITs, ground water monitoring, and any required 

atmospheric/soil gas monitoring . The amount and types of monitoring to 

be required, however, should be site specific. 

III A. 6 Proposed Plume and Pressure Front Monitoring Requirements 

JJ. In addition, EPA seeks comment regarding the use of a Directorapproved monitoring plan for GS sites. 

IOGCC Response: The Director should be given flexibility to approve 

site specific monitoring plans as proposed in the IOGCC model 

regulations. 

III A. 7 Proposed Recordkeeping and Reporting Requirements 

KK. EPA seeks comment on the merits of requiring plans for 

monitoring, AoR, and post-injection site care as part of a permit 

application. 

IOGCC Response: Yes, there should be detailed monitoring, AoR, and 

post-injection site care plans as a part of the permit consistent with the 

recommendations of the IOGCC model regulations . 

III A. 7 Proposed Recordkeeping and Reporting Requirements 

LL. EPA seeks comment on the frequency of all proposed reporting 

requirements. 
IOGCC Response: As concerns the frequency of reporting for the 

physical and chemical characteristics of the injected fluids in a Class VI 

well, IOGCC model regulations specified annual reporting although semiannual reporting (as proposed by EPA in the rule) would be acceptable . 

III A. 7 Proposed Recordkeeping and Reporting Requirements 

MM. EPA seeks comment on the requirement for electronic reporting in 

today's proposed rule. 

IOGCC Response: The IOGCC agrees with electronic submittal in 

principle as long as there is sufficient flexibility to allow states to utilize 

existing or preferred state data processing systems or software. Electronic 

reporting should be an option but not a requirement. 

III A. 7 Proposed Recordkeeping and Reporting Requirements 

NN. Although EPA has not included a requirement for this report in 

today's proposal, EPA seeks comment regarding the necessity for such 

an annual report . 

IOGCC Response: The IOGCC suggests that there be only one frequency 

of reporting, either annual or semi-annual. Thus, this requirement should 

be incorporated into the semi-annual reporting requirement enunciated by 

EPA in the rule for the physical and chemical characteristics of the 

injected fluids in a Class VI well. There should not be two different data 

reporting timeframes. 

III A. 8 Proposed Well Plugging, Post-Injection site Care, and Site Closure 

Requirements 

00. EPA requests comment on the proposed use of a tentative 50-year 

fixed timeframe that could be modified at the Director's discretion 

based on monitoring and modeling data. 

IOGCC Response: Given that current injection and reservoir behavior 

data demonstrates a decreasing risk of leakage after injection ceases, the 

IOGCC has concluded that a 50 year fixed timeframe is both unnecessary 

and too long. What is absolutely critical here is that the Director has 

discretion to increase or decrease the period based on the specifics of a 

particular project. In the view of the IOGCC, it would be better to 

prescribe a shorter period with discretion to go longer, rather than vice 

versa, as such would better facilitate project planning. 
III A. 8 Proposed Well Plugging, Post-Injection site Care, and Site Closure 

Requirements 

PP. EPA is requesting comments on the proposed requirements for 

well plugging, post-injection site care, and site closure, including the 

proposed requirements for the post-injection time period . 

IOGCC Response: Given documented evidence to date that there is a 

decreasing risk of leakage after injection ceases, The IOGCC has 

concluded that a 50 year fixed timeframe is both unnecessary and too 

long. What is absolutely critical here is that there be Director discretion to 

increase or decrease the period based on the specifics of a particular 

project. In the view of the IOGCC, it would be better to prescribe a 

shorter period with discretion to go longer, rather than vice versa, as such 

would better facilitate project planning. 

III A. 8 Proposed Well Plugging, Post-Injection site Care, and Site Closure 

Requirements 

QQ. In addition, EPA seeks comment on whether the Director should 

be allowed to shorten the timeframe based on performance 

information, and whether EPA should require a shorter or longer postinjection period if data suggests the time frame should be adjusted . 

IOGCC Response: Given documented evidence to date that there is a 

decreasing risk of leakage after injection ceases, The IOGCC has 

concluded that a 50 year fixed timeframe is both unnecessary and too 

long. What is absolutely critical here is that there be Director discretion to 

increase or decrease the period based on the specifics of a particular 

project. In the view of the IOGCC, it would be better to prescribe a 

shorter period with discretion to go longer, rather than vice versa, as such 

would better facilitate project planning. 

III A. 9 Proposed Financial Responsibility and Long-Term Care Requirements 

RR. EPA is requesting comments on whether financial responsibility 

mechanisms to be recommended in EPA guidance should be adjusted 

in the manner described, whether additional instruments should be 

included, and whether other adjustments to the financial responsibility 

mechanisms should be considered, all subject to EPA's authority under 

the SDWA. 

IOGCC Response: The EPA proposed rule for well financial assurance 

appears comprehensive enough. However, the proposed two-tier bond 

system of pre and post plugging of the well would be administratively 

cumbersome and the IOGCC would recommend one bond that covers 
operational, eventual plugging and post site remediation until the release 

date. 

The IOGCC model regulations proposed that in addition to well bonds that 

there also be an overall facility bond. The purpose of the facility bond 

would be to insure financial responsibility to address and mitigate nonwell specific issues . What EPA is suggesting in the rule needs to be 

supplemented by the states via mechanisms such as a facility bond. 

III A. 9 Proposed Financial Responsibility and Long-Term Care Requirements 

SS . The Agency is also requesting comment on allowing separate 

financial demonstrations to be submitted for the plugging of the 

injection well and for the post-injection site care requirements . 

IOGCC Response: The IOGCC model regulations proposed that in 

addition to well bonds that there also be an overall facility bond. The 

purpose of the facility bond would be to insure financial responsibility to 

address and mitigate non-well specific issues . What EPA is suggesting in 

the rule needs to be supplemented by the states via mechanisms such as a 

facility bond. 

IV. How Should UIC Program Directors Involve the Public In Permitting 

Decisions for GS Projects? 

TT . EPA requests comment on adopting the existing requirements for 

public participation at 40 CFR Part 25 and 40 CFR Part 124 and 

whether additional requirements should be included to reflect the 

availability of new tools for disseminating and gathering information. 

Such tools include cable networks, the Internet, and other new 

technology. 

IOGCC Response: All states have public notice laws and regulations that 

cover most regulatory and permitting functions. These laws and 

regulations would extend to the permitting and the regulation of GS that 

require public notice, hearings and due process to all affected parties. This 

should be adequate for public involvement purposes. 

IV. How Should UIC Program Directors Involve the Public In Permitting 

Decisions for GS Projects? 

UU. EPA also requests comment on ways to enhance the public 

participation process, including engaging communities in the site 

characterization process as soon as candidate locations are identified . 

IOGCC Response: All states have public notice laws and regulations that 

cover most regulatory and permitting functions. These laws and 
regulations would extend to the permitting and the regulation of GS that 

require public notice, hearings and due process to all affected parties. This 

should be adequate for public involvement purposes. 

V. How Will States, Territories, and Tribes Obtain UIC Program Primacy for 

Class VI Wells? 

VV. EPA is seeking comment on the merits and possible disadvantages 

of allowing primacy approval for Class VI wells independent of other 

well classes. 

IOGCC Response: The IOGCC strongly supports independent state 

primacy for Class VI. States should have the authority to designate which 

agency in the state can apply for and be granted primacy. 

VI. What Is the Proposed Duration of a Class VI Injection Permit? 

WW. Therefore, EPA proposes that Class VI injection well permits 

would be issued for the operating life of the GS project including the 

post-injection site care period. EPA seeks comment on the merits of 

this approach. 

IOGCC Response: The IOGCC agrees with the EPA proposal. 

VI. Cost Analysis 

XX. Therefore EPA proposes that Class VI injection well permits 

would be issued for the operating life of the GS project including the 

post-injection site care period . EPA seeks comment on the merits of 

this approach. 

IOGCC Response: No comment. 
Letter ID: 0263 

 Organization: Interstate Oil & Gas Compact Commission 

Letter ID: 0263 Comment ID: 22788 Letter Lines: 38 to 40 

Comment Code: 5600 2.11 Comments related to UIC Program primacy for Class VI wells 

Comment: A. Funding: It is essential that EPA provide adequate funding to states assuming 

primacy jurisdiction under the UIC program to administer CO2 storage regulatory 

activities. 

Individual Response: EPA acknowledges that there may be technical and administrative 

challenges including resource concerns, and will work closely with the states to assist them in 

resolving funding issues or acquiring the resources, personnel, and training needed to address the 

unique technical challenges associated with GS. 

EPA will also incorporate Class VI wells into the UIC Program's grant allocation process. The 

States/Tribes/Territories must also demonstrate that they have adequate resources to implement 

the program through matching resources against those allocated by the UIC Program's grant 

allocation formula. Currently, primacy programs are required to meet a minimum of 25 percent 

matching requirement. 

Letter ID: 0263 Comment ID: 22789 Letter Lines: 46 to 54 

Comment Code: 5610 2.11.1 Allowing partial primacy for Class VI wells (seeking comment) 

Comment: A. EPA seeks comment on any aspects of the ongoing State efforts to regulate the 

GS of CO2 and how these efforts might be used to better inform a final 

Federal rulemaking. 

IOGCC Response: Many states currently have primacy jurisdiction under the UIC 

program and administer Class II and other wells. Primacy should be allowed for 

Class VI and should be structured to allow flexibility in the primacy process 

and defer to the state rule where it effectively meets the intent of the federal 

requirements. 

Individual Response: EPA clarifies that the primacy approval processes for Class II and Class 

VI differ. Section 1421 of SDWA directs EPA to grant primary enforcement responsibility (or 

primacy) to the States through two statutory provisions. The first provision, under Section 1422, 

provides for a State to demonstrate that its proposed UIC program is at least as stringent as the 

minimum Federal requirements in order to prevent endangerment of USDWs. The second 

provision, under Section 1425, allows a State to submit an alternative demonstration for its Class 

II program (oil and gas), where the State only has to demonstrate that its proposed Class II 

program is an effective program to prevent underground injection that endangers USDWs. 

1
EPA clarifies that Class VI wells are regulated under Section 1422 of SDWA, and adds that 

states should be able to obtain primacy for Class VI wells independent of other well classes 

provided they develop regulations that are at least as stringent as the minimum Federal 

requirements (e.g., permitting, inspection, operation, monitoring, and recordkeeping 

requirements) provided in the final GS rule. 

EPA acknowledges the expertise of state oil and gas agencies that have been regulating Class II 

wells for decades under section 1425 of SDWA. These agencies already understand CO2 

injection, subsurface operations, and pipeline transport, and they are familiar with public 

interests and the SDWA. EPA believes that this experience, along with the agencies' familiarity 

with UIC permitting requirements, will help facilitate the adoption of Class VI primacy 

programs. 

Letter ID: 0263 Comment ID: 22790 Letter Lines: 56 to 66 

Comment Code: 2046 1.5.2.3 Continuing to classify CO2 injection for EOR/EGR as Class II/ 

dividing line between Class II and Class VI (seeking comment) 

Comment: II. G. How Would This Proposal Affect Existing Injection Wells Under the UIC 

Program? 

B. EPA seeks comment on the merits of this approach since owners or operators 

of some Class II EOR/EGR wells may wish to use wells for the purposes of production 

and GS prior to the field being completely depleted. 

IOGCC Response: The IOGCC agrees with EPA's proposed approach as long as the 

project is an EOR project under Class II and the operator has been able to 

demonstrate viable production. EPA should consider a separate classification 

other than the proposed Class VI, as well as requisite requirements, for wells 

that are transitioned from Class II EOR to Class II related storage. 

Individual Response: EPA agrees that injection of CO2 for the primary purpose of enhancing 

oil and gas recovery should remain under the Class II Program. However, the Agency believes 

that the nature and risks of CO2 injection for the primary purpose of long term storage poses 

different risks than injection for the primary purpose of ER, and therefore has developed new 

Class VI regulations to address these unique risks. For example, the volume of CO2 anticipated 

to be injected for long term storage is significantly greater than for ER operations. Reservoir 

pressure conditions will also be different, with Class VI injection operations involving large 

volumes of CO2 and likely having higher pressures within their storage formations than Class II 

ER projects. 

EPA is developing guidance on transitioning permits from Class II to Class VI. The guidance 

will assist Directors in determining whether an injection project should be transitioned from 

Class II where the primary purpose is oil and gas production to Class VI where the primary 

2
purpose is long-term storage of large volumes of CO2. The guidance describes the recommended 

methods the Director may use to evaluate changes in risk to USDWs from projects, and how the 

Director may determine whether a project should be regulated within the Class II or Class VI 

UIC program. This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. For more information, please 

see the discussion on transition of Class II wells in the preamble to the final GS rule. 

Letter ID: 0263 Comment ID: 22791 Letter Lines: 68 to 118 

Comment Code: 2060 1.5.3 Comments on grandfathering of existing wells (seeking comment) 

Comment: II . G. How Would This Proposal Affect Existing Injection Wells Under the UIC 

Program? 

C. EPA is proposing to give the Director discretion to carry over or 

"grandfather" the construction requirements (e.g., permanent, cemented well 

components) for existing Class I and Class II wells seeking a permit for GS of CO2, 

provided he/she is able to make a determination that these wells would not 

endanger USDWs. 

IOGCC Response: The IOGCC agrees that discretion is appropriate and necessary 

when reviewing other UIC class wells for use as UIC Class VI wells or another 

class of well as suggested in the response to II.G(B) above. 

II . G. How Would This Proposal Affect Existing Injection Wells Under the UIC Program? 

D. Accordingly, EPA is proposing that the Director have the discretion to 

"grandfather" the construction requirements for Class Experimental wells when 

they are converted to full-scale GS Class VI wells. As with converted Class I 

and Class II wells, these grandfathered wells would be required to meet the 

other requirements of today's proposed rule (e.g., operating, monitoring, MIT, 

well plugging, post-injection site care and site closure). 

IOGCC Response: The IOGCC agrees that discretion is appropriate and necessary 

when reviewing other UIC class wells for use as UIC Class VI wells or another 

class of well as suggested in the response to II. G(B) above. 

11. G. How Would This Proposal Affect Existing Injection Wells Under the UIC Program? 

E. EPA seeks comment on the approach to grandfather construction requirements at 

the Director's discretion for existing Class I, Class II, and Class V wells 

seeking to convert to Class VI wells, and whether additional construction 

requirements would be necessary to prevent endangerment to USDWs from the GS 

of CO2. 

IOGCC Response: As part of the primacy package negotiated with the state, when an 

3
operator submits an application to reclassify any existing injection well to Class 

VI or other storage well classification, the Director should have the 

flexibility to determine whether the well meets the federal Class VI or another 

storage well classification which incorporates protective standards and requires 

the operator to adhere to the permitting process. 

II. G. How Would This Proposal Affect Existing Injection Wells Under the UIC Program? 

F. Additionally, EPA seeks comment on how the grandfathering approach for 

existing wells may affect compliance with the requirements in this proposal. 

IOGCC Response: As part of the primacy package negotiated with the state, when an 

operator submits an application to reclassify any existing injection well to Class 

VI or other storage well classification, the Director should have the flexibility 

to determine whether the well meets the federal Class VI or another storage well 

classification which incorporates protective standards and requires the operator 

to adhere to the permitting process. 

Individual Response: EPA agrees that many Class I, Class II, and Class V experimental 

technology wells are designed and constructed to withstand exposure to CO2. The final GS rule 

provides for the construction of these wells to be grandfathered per §146.81(c), provided the 

owner or operator can demonstrate to the Director that the wells were engineered and constructed 

to meet the requirements at §146.86(a) and ensure protection of USDWs, in lieu of requirements 

at §146.86(b) and §146.87(a). EPA clarifies that only the construction requirements are 

grandfathered and that all other Class VI requirements (reporting, monitoring, mechnical 

integrity testing, etc.) must be met following a determination under §146.81(c). 

The final Class VI regulations require that any owner or operator injecting CO2 for the primary 

purpose of long term storage obtain a Class VI permit with some special consideration for the 

fact that they are transitioning from a well not originally designed to meet Class VI requirements. 

The Director has the authority to determine at what point a Class VI permit is required for those 

projects that are transitioning from the primary purpose of EOR to long term storage of CO2. 

The final regulation provides a set of technical factors for the Director to evaluate in making this 

determination, at §144.19. EPA believes that this approach provides sufficient protection of 

USDWs when there is an increased risk to USDWs as compared to traditional Class II operations 

while allowing for site-specific flexibility. 

EPA is developing guidance on transitioning permits from Class II to Class VI. The guidance 

will assist Directors in evaluating when and whether an injection project should be transitioned 

from Class II where the primary purpose is oil and gas production to Class VI where the primary 

purpose is long-term storage of CO2. The guidance describes recommended methods for the 

Director to evaluate when determining changes in risk to USDWs from projects, and how the 

Director may determine whether a project should be regulated within the Class II or Class VI 

UIC program. This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

4
Letter ID: 0263 Comment ID: 22792 Letter Lines: 120 to 128 

Comment Code: 4324 2.4.4.1.2 Comments opposed to requiring injection below the lowermost 

USDW 

Comment: II. H. What Are the Target Geologic Formations for GS of CO2? 

G. As with unmineable coal seams, EPA seeks comment on prohibiting injection into 

such formations if they are above the lowermost USDW. 

IOGCC Response: There should be no blanket prohibition against injection into any 

approved geologic zone even if above the lowermost USDW. There maybe 

circumstances where this is perfectly appropriate and safe. The decision needs to be 

site-specific and based on evaluation of local geology. 

Individual Response: EPA acknowledges that there are limited circumstances where injection 

above the lowermost USDW can be performed in a manner that protects USDWs from 

endangerment, as long as appropriate protections are in place. The final GS rule at §146.95 

establishes a process by which owners or operators can seek a waiver of the Class VI injection 

depth requirements for injection into non-USDW formations above and/or between USDWs. 

Additionally, the final GS rule does not categorically preclude or prohibit injection into any type 

of formation. 

EPA believes that these requirements will ensure USDW protection while providing flexibility to 

UIC program Directors and owners or operators who undertake CO2 injection for GS. The 

Agency believes this approach: 1) responds to concerns about local and regional geologic storage 

capacity limitations imposed by the proposed injection depth requirements; 2) allows for a more 

site-specific assessment of injection depth for GS projects; 3) accommodates injection into 

different formation types; 4) allows for injection of CO2 for GS into non-USDWs above and/or 

between USDWs when appropriate and where it can be demonstrated that USDWs will be 

protected; and 5) responds to concerns about the use of aquifer exemptions for GS. Finally, 

EPA’s approach to addressing injection depth variability through a waiver process responds to 

concerns about future drinking water resource availability and the need to ensure that high 

quality water remains available in sufficient quantities to supply drinking water needs. For 

additional information on the waiver approach, please see the final rule and preamble, as well as 

EPA's responses to comments on the Notice of Data Availability and Request for Comment. 

Letter ID: 0263 Comment ID: 22793 

Comment: Individual Response: 

Letter ID: 0263 Comment ID: 22794 Letter Lines: 149 to 165 

5
Comment Code: 2300 1.7 Comments on the Alternatives Considered 

Comment: III . Proposed Regulatory Alternatives 

J. EPA is proposing Regulatory Alternative 3, the Tailored Requirements Approach. 

EPA did not select alternative 1 (Non-Specific Requirements Approach) because it 

does not provide enough specificity to ensure that permitting authorities manage 

GS wells appropriately to prevent endangerment of USDWs. In addition, this 

alternative maybe burdensome for owners or operators because of the potential for 

inconsistency across States and burdensome for permitting authorities who will 

likely be faced with developing their own technical approaches to regulating GS. 

IOGCC Response: The IOGCC strongly believes that Alternative II is the better 

approach with some additional strengthening. This would allow necessary 

discretion and flexibility on the part of the Director. The alternative proposed 

by EPA, Alternative III, although described as "giving permitting authorities 

discretion in how to permit certain elements" appears to offer very limited 

discretion and flexibility to the Director. Alternative III is unnecessarily 

prescriptive. 

Individual Response: Although Alternative 2 (General Requirements Approach) provides 

standards for siting, construction, operation, and monitoring associated with basic deep well 

design and operation, EPA does not believe that this alternative is appropriate for GS because it 

does not contain requirements tailored to meet the unique challenges of long-term CO2 GS, 

including the potentially large injection volumes, buoyancy, corrosivity in the presence of water, 

and viscosity and therefore cannot ensure protection USDWs. 

EPA believes that the GS rule offers states the flexibility and discretion desired by commenters 

preferring Alternative 2 while ensuring the protection of USDWs. The final GS regulation gives 

the Director discretion to set permit criteria that are appropriate to site-specific conditions. The 

regulation provides flexibility to select appropriate sites and target formations (under §146.82), 

well construction specifics (under §146.86), and testing and monitoring regimes (under §146.90), 

provided the owner or operator can demonstrate that the injection and storage will not endanger 

USDWs and that minimum requirements for the site are met. Commenters representing electric 

utilities, water associations, and states supported Alternative 3 and the flexibility it provides to 

permitting authorities to make case-by-case permitting decisions while ensuring the protection of 

USDWs. 

Letter ID: 0263 Comment ID: 22795 Letter Lines: 167 to 177 

Comment Code: 3120 2.1.2 Need to identify additional confining and containment zones 

(seeking comment) 

Comment: III A. 1 Proposed Geologic Siting Requirements 

K. EPA specifically seeks comment on the merits of identifying these additional zones. 

6
IOGCC Response: Secondary confinement should not be a requirement. Such a 

requirement would eliminate good and sound storage sites and reduce ultimate 

capacity of the country to store anthropogenic CO2. The determination as to 

whether secondary confinement should be required should be made on a project by 

project basis and be site specific. It is possible to hypothesize a circumstance 

where secondary confinement is not necessary with the addition of stronger 

monitoring requirements. 

Individual Response: EPA clarifies that secondary confining zones are not required for all GS 

sites. Rather, secondary confining zones are required when the Director determines that these 

zones are needed to maximize the protection of USDWs from endangerment. EPA retains the 

requirement to identify additional containment/confining zones, if required by the Director, as 

proposed (e.g., §146.83(b)). EPA believes that, in some situations, the presence of additional 

confining and containment zones above the primary (i.e., lowermost) confining zone can 

improve USDW protection. These layers could further impede vertical fluid movement and 

allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and 

remediation. EPA disagrees that the requirement would reduce the number of sites available for 

GS. The intent of this requirement is to ensure that a proposed site provides adequate protection 

of USDWs from endangerment; if this protection cannot be demonstrated, the Director would not 

issue a permit for GS at the site. 

Letter ID: 0263 Comment ID: 22796 Letter Lines: 179 to 186 

Comment Code: 3200 2.2 Proposed Area of Review and Corrective Action Requirements (40 

CFR 146.84) 

Comment: III A. 2 Proposed Area of Review and Corrective Action Requirements 

IOGCC General Comment for Section lIl. A. 2: The IOGCC believes use of traditional 

well specific AoR is problematic for comprehensive site characterization and 

licensing. The IOGCC has recommended in its report a site characterization and 

licensing process that includes elements such as geologic and engineering 

evaluation, modeling, amalgamation of property rights and other appropriate 

elements that we believe exceeds the capacity of the traditional AoR to accomplish. 

Individual Response: EPA agrees that the AoR for a GS project should incorporate site 

characterization include elements such as geologic and engineering evaluation, modeling, and 

other appropriate elements, EPA clarifies that the area of review must be delineated using 

computational modeling that is based on available site characterization, monitoring, and 

operational data. EPA is developing guidance on AoR and corrective action at GS Class VI sites 

to assist owners/operators and Directors in evaluating requirements and proposed AoR and 

corrective action plans under 146.84. The guidance describes EPA's recommended approaches 

for the data to be considered in an initial AoR delineation, how to apply computational modeling 

to delineate the AoR, performing corrective action at GS sites, and, when appropriate, 

completing AoR reevaluations. The guidance will be available on EPA's web site, at 

7
http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

EPA clarifies that the purpose of the GS regulation is to ensure the safe injection of CO2 through 

GS wells in order to protect USDWs from endangerment. Property, water, or mineral rights 

possibly affected by a GS project are outside the scope of this rule and therefore are not 

incorporated into the AoR definition at 146.84(a). 

Letter ID: 0263 Comment ID: 22797 Letter Lines: 188 to 196 

Comment Code: 3320 2.2.1.2 Comments opposed to requiring computational models to 

delineate the AoR 

Comment: III A. 2 Proposed Area of Review and Corrective Action Requirements 

L. EPA seeks comment on the use of modeling for AoR delineation. 

IOGCC Response: See General Comment for Section III. A. 2 above. The collection 

of physical data (i.e. well bore data) maybe necessary to fully utilize modeling 

to determine the ultimate extent of the proposed CO2 storage volume. Models should 

only be used when they are appropriate. The Director needs the flexibility to be 

able to supplement or substitute other data elements as appropriate. 

Individual Response: EPA agrees that it is appropriate to allow operators the flexibility to select 

modeling, site characterization, and monitoring techniques that are most appropriate to site 

conditions and available types and amounts of data. However, EPA believes that modeling is 

necessary to delineate the AoR for GS projects, and the final rule retains this requirement. EPA 

notes that the final rule at 146.84(c)(1) requires the AoR to be predicted using existing site 

characterization, monitoring, and operational data, along with computational modeling, but that 

it does not specify the particular data inputs. EPA adds that the final rule at 146.82(c)(1) requires 

the owner or operator to revise the proposed AoR submitted under 146.82(a)(2) as necessary to 

address new data collected during logging and testing. 

Letter ID: 0263 Comment ID: 22798 Letter Lines: 198 to 205 

Comment Code: 3350 2.2.1.5 Use of proprietary models for GS sites (seeking comment) 

Comment: III A. 2 Proposed Area ofReview and Corrective Action Requirements 

M. EPA seeks comment on allowing the use of proprietary models for GS sites. 

IOGCC Response: Proprietary models should be allowed provided the Director has 

discretion to evaluate the accuracy of the modeling methodology. It should be 

noted that confidentiality of proprietary models will be subject to statutory 

limitation in various jurisdictions. 

8
Individual Response: EPA will allow the use of proprietary models in meeting the requirements 

for the GS regulation, but clarifies that GS well operators using proprietary models are required 

to disclose, to the Director's satisfaction, the code assumptions, relevant equations, and scientific 

basis. 

EPA adds that its Confidential Business Information requirements at 40 CFR 144.5 will apply to 

the use of proprietary models. Information including model assumptions and equations are used 

by the Director to inform his/her decision to issue the permit and ensure that the requirements are 

met and the GS well will not endanger USDWs. 

The Agency plans, every six years, to collect and review data on GS projects to determine 

whether the appropriate amount and types of information and appropriate documentation are 

being collected, and to determine if modifications to the requirements are appropriate or 

necessary. 

Letter ID: 0263 Comment ID: 22799 Letter Lines: 207 to 217 

Comment Code: 3330 2.2.1.3 Applicability /adequacy of computational models (seeking 

comment) 

Comment: III A. 2 Proposed Area of Review and Corrective Action Requirements 

N. EPA seeks comment on the applicability of computational fluid flow models for 

delineating the AoR ofGS sites. 

IOGCC Response: See General Comment for Section III. A. 2 above. The collection 

of physical data (i.e. well bore data) maybe necessary to fully utilize modeling 

to determine the ultimate extent of the proposed CO2 storage volume. Models should 

only be used when they are appropriate. The regulator of a GS project should not 

be required to rely fully on models. As noted above, states need the flexibility 

to be able to go beyond models. 

Individual Response: EPA agrees that a detailed geologic assessment is essential to evaluating 

the presence and adequacy of a proposed site to receive and confine the CO2. The AoR and 

corrective action plan required at §146.84(b) must describe the site characterization data on 

which the model will be based. The Director has discretion to require the use of existing data if it 

is not initially included. 

EPA clarifies that the model inputs must include actual geologic information, data collected 

during the site characterization process (e.g., information about artificial penetrations), and 

anticipated operating parameters (e.g., injection rates) submitted with the permit application 

under §146.82. Models will be revised and recalibrated during subsequent AoR reevaluations, 

which must account for all available monitoring and operational data, as required at §146.84(e). 

9
The Agency believes that predicting the complex multiphase buoyant flow of the CO2, coinjectates, and compounds that may be mobilized due to injection requires the sophistication of 

computational models. Models can predict CO2 fate and transport, as well as changes in 

formation pressure, in three dimensions, as a function of time in order to delineate the subsurface 

storage site and the AoR. Models can account for site-specific and predicted operating conditions 

as well as geologic heterogeneities and potential migration through faults, fractures, and artificial 

penetrations. 

EPA agrees that it is appropriate to allow operators the flexibility to select modeling, site 

characterization, and monitoring techniques that are most appropriate to site conditions and 

available types and amounts of data. The owner or operator must demonstrate, in the proposed 

AoR and corrective action plan at §146.84(b), to the satisfaction of the Director that the modeled 

AoR will be based on detailed geologic data collected on the site. 

Letter ID: 0263 Comment ID: 22800 Letter Lines: 219 to 232 

Comment Code: 3530 2.2.3.1 AoR reevaluation frequency (seeking comment) 

Comment: III A. 2 Proposed Area ofReview and Corrective Action Requirements 

O. EPA seeks comment on requiring the reevaluation of the site AoR on a periodic 

basis, under what conditions the AoR should be reevaluated, and the 

appropriateness of a 10 year minimum fixed frequency for AoR reevaluation. 

IOGCC Response: Note: This comment is based on the traditional AoR requirement. 

Most states do an annual project review with the operator not only to evaluate 

the project's performance but to determine if additional measures are needed. 

Setting a frequency should be performance based and should be left to the 

Director's discretion, but in no event less than every two years. Only if the 

review determines that remodeling, further study or additional downhole monitoring is necessary, should such work be done. Additionally, such 

additional work should be done as needed, not at a set time interval. 

Individual Response: EPA believes that periodic AoR reevaluation at a set frequency of at least 

every 5 years is necessary to ensure protection of USDWs from endangerment and address the 

uncertainties inherent in predictive modeling. Periodic AoR reevaluations at §146.84(e) ensure 

that a deliberate effort is made to verify, based on monitoring and operational data, that the CO2 

plume is moving within the subsurface as predicted. EPA believes that less frequent 

reevaluations may not be sufficient to appropriately model plume and pressure front movement, 

establish conditions for corrective action, and ensure protection of USDWs from endangerment. 

EPA adds that the AoR and corrective action plan must specify the site-specific monitoring and 

operational conditions that warrant reevaluation, as specified in §146.84(b)(2)(ii). In addition, 

10
the Director has discretion to require more frequent AoR reevaluation if he or she has reason to 

believe, based on site-specific information, that a five-year reevaluation schedule is not 

sufficiently protective of USDWs. 

Letter ID: 0263 Comment ID: 22802 Letter Lines: 243 to 252 

Comment Code: 1250 1.1.1.4 Flexibility is needed (performance-based standards) 

Comment Code: 3820 2.3.1 Well construction procedures 

Comment: III A. 3 Proposed Injection Well Construction Requirements 

Q. EPA seeks comment on the proposed GS well requirements for depth of surface 

casing, the cementing of long-string casing, and construction with a packer set 

opposite a cemented interval. 

IOGCC Response: IOGCC agrees with the need for adequate protection of USDWs and the 

proposed measures. However, Director discretion is necessary to address sitespecific conditions. Well construction should be evaluated so as to insure 

necessary protections of the USDWs, and should not be overly prescriptive. 

Individual Response: EPA agrees that, given the continuing evolution of material design and 

the numerous variables possible in a long-term GS project, listing specific requirements for 

casing and cement would not be appropriate. Rather, requiring that materials must have 

sufficient structural strength and be compatible with fluids with which they may come in contact, 

in §146.86(b)(1), allows the owner or operator to determine the best casing and cementing design 

for each project based on information about the site and the planned injection and for the 

Director to approve that design. 

See the discussion of Class VI well construction requirements in the preamble to the final GS 

rule for additional information. Additionally, EPA is developing guidance on the construction of 

Class VI wells. This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Letter ID: 0263 Comment ID: 22803 Letter Lines: 254 to 263 

Comment Code: 2060 1.5.3 Comments on grandfathering of existing wells (seeking comment) 

Comment: III A. 3 Proposed Injection Well Construction Requirements 

R. EPA also seeks comment on how the proposed grandfathering provisions for 

existing wells (construction requirements) may affect compliance with the above, 

proposed construction requirements. 

IOGCC Response: The IOGCC believes that Director discretion is appropriate and 

11
necessary when reviewing other UIC Class wells for use as UIC Class VI wells. 

Overly prescriptive well construction requirements will limit the use of existing 

UIC wells and possible sequestration zones. 

Individual Response: As described above, EPA agrees that many Class I, Class II, and Class V 

experimental technology wells are designed and constructed to withstand exposure to CO2. The 

final GS rule provides for the construction of these wells to be grandfathered per §146.81(c), 

provided the owner or operator can demonstrate to the Director that the wells were engineered 

and constructed to meet the requirements at §146.86(a) and ensure protection of USDWs, in lieu 

of requirements at §146.86(b) and §146.87(a). 

Letter ID: 0263 Comment ID: 22804 Letter Lines: 265 to 272 

Comment Code: 3840 2.3.2 Horizontal well drilling techniques (seeking comment) 

Comment: III A. 3 Proposed Injection Well Construction Requirements 

S. EPA seeks comment on the merits of horizontal well drilling techniques for GS 

wells and the applicability of well construction requirements discussed in this 

proposal. 

IOGCC Response: With Director discretion horizontal well drilling techniques 

maybe appropriate for GS application. 

Individual Response: In this final rule, EPA allows the use of horizontal wells at GS projects. In 

the proposed rule, EPA sought comment on the appropriateness of horizontal drilling techniques 

for Class VI wells, and commenters representing energy companies, electric utilities, the oil and 

gas industry, CCS associations, states, and the public, unanimously supported the concept and 

provided many reasons why horizontal wells could be beneficial at GS sites. Based on an 

evaluation of these comments and additional research by EPA, the Agency has concluded that 

horizontal wells that are properly constructed, logged, and tested for mechanical integrity (i.e., to 

meet the requirements of the GS rule) can ensure the protection of USDWs from endangerment. 

EPA adds that all proposed construction, including the use of horizontal wells, must be approved 

by the Director. 

Letter ID: 0263 Comment ID: 22805 Letter Lines: 274 to 283 

Comment Code: 3862 2.3.3.1 Use of corrosion-resistant construction materials (seeking 

comment) 

Comment Code: 3864 2.3.3.2 Use of corrosion-resistant cements (seeking comment) 

Comment: III A. 3 Proposed Injection Well Construction Requirements 

T. EPA seeks comment regarding requirements for degradation-resistant well 

construction materials, such as acid-resistant cements and corrosion resistant 

12
casing. 

IOGCC Response: Concerning degradation-resistant well construction materials, the 

EPA rule should not be overly prescriptive but instead set a performance standard 

that would allow on a case by case basis the cementing materials necessary to 

meet the standard. 

Individual Response: EPA clarifies that corrosion-resistant materials are not specifically 

required in a Class VI injection well. Rather, as stated in §146.86(b)(1), casings and cement and 

other materials used must have sufficient strength and be designed for the life of the 

sequestration project. Further, materials must meet standards established in the rule and be 

compatible with fluids with which the materials may be expected to come into contact. EPA 

believes the rule provides an appropriate amount of flexibility. The construction requirements at 

§146.86 provide flexibility by listing the basic components a Class VI well must have to prevent 

endangerment of USDWs, and allow owners or operators to choose appropriate materials in 

meeting these requirements. 

The Director will evaluate the appropriateness of the proposed well construction based on sitespecific information about the injection project, including injection pressures, injection and 

confining zone lithology, and information about the carbon dioxide stream as provided in 

§146.86(b)(1). In addition to the flexibility given to the owner and operator, Director's discretion 

is specifically provided in §146.86(b)(1) for casing and cementing and §146.86(c)(2 and 3) for 

tubing and packer location and type. EPA is developing guidance on the construction of Class VI 

wells. This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Letter ID: 0263 Comment ID: 22806 Letter Lines: 285 to 294 

Comment Code: 4120 2.4.1.2 Allowing hydraulic fracturing during GS (seeking comment) 

Comment Code: 4130 2.4.1.3 Appropriateness of using fracturing for well stimulation (seeking 

comment) 

Comment: III A. 4 Proposed Injection Well Operating Requirements 

U. EPA is requesting comment on the extent and scope to which hydraulic fracturing 

should be allowed during GS injection, and whether the use of fracturing for the 

purposes of well stimulation is appropriate. 

IOGCC Response: While hydraulic fracturing maybe necessary in some cases to 

complete an injection well, it should not be allowed during GS injection. 

Any fracturing during well completion stimulation should be engineered so as to 

eliminate any risk of damage to confining zones. 

Individual Response: EPA emphasizes that fracturing of the confining zone during injection 

and/or stimulation is prohibited, as specified at §146.88(a). However, EPA believes there are 

some circumstances where fracturing of the injection zone may be acceptable, provided the 

13
integrity of the confining system remains unaffected and maintains USDW protection. EPA 

clarifies that §146.88(a) permits injection pressure to exceed 90 percent of the fracture pressure 

only during well stimulation. The final rule allows the use of hydraulic fracturing at GS sites, 

where approved by the Director. Hydraulic fracturing is one of several stimulation technologies 

available to improve wellbore and formation injectivity. 

EPA clarifies that all stimulation, including hydraulic fracturing, must be approved by the 

Director. Owners or operators must submit a proposed stimulation program as part of the permit 

application under §146.82(a)(9); the plan must demonstrate that any stimulation activities will 

not compromise the integrity of the confining zone. The Director will evaluate the owner or 

operator's proposed stimulation plan in the context of all information about the site, and the 

owner or operator must perform stimulation only as approved. 

The final rule at §146.91(d)(2) also requires that the owner or operator notify the Director 30 

days before performing stimulation during the operational phase of a GS project; this will 

provide an additional opportunity for the Director to review the owner or operator's plans for 

stimulation and add other requirements as needed. 

Letter ID: 0263 Comment ID: 22807 Letter Lines: 296 to 310 

Comment Code: 4140 2.4.1.4 Use of fracturing for GS in specific geologic settings (seeking 

comment) 

Comment: III A. 4 Proposed Injection Well Operating Requirements 

V. EPA is also requesting information to better qualify the use of fracturing for 

GS injection in specific geologic settings and rock formation lithologies. 

IOGCC Response: As indicated above, hydraulic fracturing should only be allowed 

during the initial completion or recompletion of a well to enhance reservoir 

permeability. However, once the completion phase has ended and the operational or 

injection phase has begun, fracturing during injection should never be 

permitted. It is important to keep separate the concept of operational injection 

pressure limits and episodic well stimulation activities. 

In this respect, there should be no injection above the allowable permitted 

pressure. Additionally, hydraulic fracturing of the caprock should never be 

allowed nor should pressure testing of the confining layer. 

Individual Response: As described above, the final GS regulation allows hydraulic fracturing 

only during Class VI well stimulation, as specified at §146.88(a). EPA acknowledges that in 

some circumstances hydraulic fracturing during a well workover may be appropriate. The final 

rule at §146.91(d)(2) includes a requirement that the owner or operator notify the Director 30 

days before performing stimulation during the operational phase of a GS project; this will 

provide an additional opportunity for the Director to review the owner or operator's plans for 

stimulation and add other requirements as needed. EPA clarifies that UIC regulations prohibit 

14
fracturing of the confining zone at any time during injection or stimulation in order to protect 

USDWs from endangerment. 

Letter ID: 0263 Comment ID: 22808 Letter Lines: 312 to 320 

Comment Code: 4200 2.4.2 Down-hole shut-off valves in GS wells (seeking comment) 

Comment: III A. 4 Proposed Injection Well Operating Requirements 

W. EPA seeks comment on the merits of requiring down-hole shut-off valves in GS 

wells. 

IOGCC Response: There should be no hard and fast requirement for a down-hole 

shut-off valve in a GS well. Down-hole shut-off valves may, however, at Director 

discretion provide a necessary extra level of protection in more sensitive 

settings. 

Individual Response: After evaluating the risks and benefits of down-hole shut-off systems and 

considering additional research, EPA will not require automatic down-hole shut-off devices for 

onshore Class VI wells since it is not necessary in all cases to ensure protection of USDWs from 

endangerment. Instead, the final rule, at §146.88(e)(2), requires that owners or operators of 

onshore Class VI wells install automatic surface shut-off devices. The rule affords Director's 

discretion to mandate automatic down-hole shut-off devices in onshore situations that may 

warrant their use. However, the Agency believes that offshore Class VI wells present unique 

construction and operational conditions, including isolation from shorelines and the need to 

construct wells through the water column and the subsurface, which may delay response time in 

the event of well difficulties. The rule requires, at §146.88(e)(3), that owners or operators of 

offshore wells within State territorial waters install automatic down-hole shut-off systems. EPA 

believes that these requirements at §146.88(e) ensure that proper precautions are taken to prevent 

subsurface fluid movement and ensure protection of USDWs. 

Letter ID: 0263 Comment ID: 22809 Letter Lines: 322 to 332 

Comment Code: 4324 2.4.4.1.2 Comments opposed to requiring injection below the lowermost 

USDW 

Comment: III A. 4 Proposed Injection Well Operating Requirements 

X. As a result, the Agency is considering and requesting comment on alternative 

approaches that would allow injection between and/or above the lowermost USDW, 

and thus potentially allow for more areas to be available for GS while preventing 

USDW endangerment. 

IOGCC Response: There should be no blanket prohibition against injection into a 

zone even if above the lowermost USDW. There maybe circumstances where it is 

15
perfectly appropriate and safe. The decision needs to be site specific based on 

local geologic conditions. 

Individual Response: As described above, EPA acknowledges that there are limited 

circumstances where injection above the lowermost USDW can be performed in a manner that 

protects USDWs from endangerment, as long as appropriate protections are in place. The final 

GS rule at §146.95 establishes a process by which owners or operators can seek a waiver of the 

Class VI injection depth requirements for injection into non-USDW formations above and/or 

between USDWs. Additionally, the final GS rule does not categorically preclude or prohibit 

injection into any type of formation. 

Letter ID: 0263 Comment ID: 22810 Letter Lines: 334 to 343 

Comment Code: 4324 2.4.4.1.2 Comments opposed to requiring injection below the lowermost 

USDW 

Comment: III A. 4 Proposed Injection Well Operating Requirements 

Y. In summary, EPA is soliciting comment on whether CO2 injection should be 

allowed into an injection zone above the lowermost USDW, when the Director 

determines that geologic conditions (e.g., thousands of feet of intervening 

formations between the injection zone and the overlying and/or underlying USDWs) 

exist that will prevent fluid movement into adjacent USDWs. 

IOGCC Response: Injection criteria on which zones to use should be site specific 

based on local geologic conditions. 

Individual Response: As described above, EPA acknowledges that there are limited 

circumstances where injection above the lowermost USDW can be performed in a manner that 

protects USDWs from endangerment, as long as appropriate protections are in place. The final 

GS rule at §146.95 establishes a process by which owners or operators can seek a waiver of the 

Class VI injection depth requirements for injection into non-USDW formations above and/or 

between USDWs. Additionally, the final GS rule does not categorically preclude or prohibit 

injection into any type of formation. 

Letter ID: 0263 Comment ID: 22811 Letter Lines: 345 to 354 

Comment Code: 4460 2.4.4.4.1 Comments in favor of allowing aquifer exemptions in certain 

circumstances 

Comment: III A. 4 Proposed Injection Well Operating Requirements 

Z. EPA is also requesting comments on whether aquifer exemptions should be 

allowed for the purpose of Class VI injection, and under what conditions should 

such aquifer exemptions be approved. 

16
IOGCC Response: Aquifer exemptions under Class VI should be allowed on the 

same basis as for other classes. Each exemption should be considered on its own 

merits based on local geologic conditions and the likelihood of use of the zone 

for future public water supply. 

Individual Response: EPA acknowledges that there are limited circumstances where aquifer 

exemptions for GS may be warranted. The final rule allows for the expansion of the areal extent 

of existing aquifer exemptions for Class II EOR/EGR wells transitioning to Class VI injection 

for GS pursuant to requirements at §§146.4 and 144.7(d). Class VI owners or operators granted 

expansions of existing Class II EOR/EGR aquifer exemptions for GS projects must meet all of 

the tailored requirements for GS wells in the final GS rule. 

However, the final rule precludes the issuance of new aquifer exemptions for Class VI GS wells; 

that is, aquifer exemptions will only be granted for projects that are transitioning from Class II 

EOR/EGR wells to Class VI. 

EPA clarifies that all decisions regarding whether expansion of existing aquifer exemptions will 

be at the Director's discretion and based on site-specific information. If an owner or operator 

applies for a Class VI permit to inject CO2 into a previously exempted aquifer (non-USDW) that 

is located above and/or between USDWs, the permit applicant must also apply for a waiver of 

the injection depth requirements pursuant to §146.95 to ensure that if a waiver is granted, 

USDWs above and below the injection zone are protected from endangerment. 

This approach is designed to ensure that the differences between traditional Class II EOR/EGR 

operations and Class VI operations are considered during the aquifer exemption application 

process and the Class VI permitting process. These differences include the anticipated large CO2 

injection volumes associated with GS, the buoyant and mobile nature of the injectate, and its 

corrosivity in the presence of water. The Agency believes that this process will encourage 

owners or operators and Directors to consider the use of alternative formations for GS, including 

non-USDW formations through the waiver process, prior to applying for or approving aquifer 

exemption expansions for Class II EOR/EGR wells transitioning to Class VI GS operations. 

For additional information on aquifer exemptions for Class VI wells, please see the final rule and 

preamble, as well as EPA's responses to comments on the Notice of Data Availability and 

Request for Comment 

Letter ID: 0263 Comment ID: 22812 Letter Lines: 356 to 363 

Comment Code: 4344 2.4.4.2.2 Comments opposed to setting a minimum injection depth 

Comment: III A. 4 Proposed Injection Well Operating Requirements 

AA. Finally, EPA seeks comment on whether the Agency should set a 

minimum injection depth requirement for CO2 GS,rather than require that such 

injection take place below the lowermost USDW. 

17
IOGCC Response: EPA should not set a minimum injection depth requirement for CO2 GS 

as it is unnecessary. The rule needs to allow site specific flexibility. 

Individual Response: EPA agrees that it is not appropriate to set a minimum injection depth for 

GS projects and the Agency believes that a determination of site-suitability for GS (i.e., that 

subsurface formations will receive and confine injected CO2) should be made on a site-specific 

basis. The GS rule, at §146.82, requires the owner or operator to provide extensive site- and 

project-specific information to the Director to demonstrate that the site meets the minimum site 

criteria at §146.83, that the CO2 will be contained within the injection formation, and that 

USDWs will be protected from endangerment. 

EPA acknowledges that there are limited circumstances where injection above the lowermost 

USDW can be performed in a manner that protects USDWs, as long as appropriate protections 

are in place. The final GS rule at §146.95 establishes a process by which owners or operators can 

seek a waiver of the Class VI injection depth requirements for injection into non-USDW 

formations above and/or between USDWs. The waiver approach requires the submission of 

extensive, site-specific information (in conjunction with the permit application submission) to 

demonstrate that injection of CO2 into a non-USDW that is above or between USDWs can be 

done in a manner that is protective of USDWs. The requirements are designed to ensure that the 

owner or operator, the Director, and the Regional Administrator consider, on a site specific basis, 

the implications, benefits, and challenges associated with GS and ensuring water availability and 

USDW protection. For additional information on the waiver approach, please see the final rule 

and preamble, as well as EPA's responses to comments on the Notice of Data Availability and 

Request for Comment. 

Letter ID: 0263 Comment ID: 22813 Letter Lines: 365 to 374 

Comment Code: 4490 2.4.5 Use of tracers and potential impact on human health or ecosystems 

(seeking comment) 

Comment: III A. 4 Proposed Injection Well Operating Requirements 

BB. EPA seeks comment on the use of tracers in CO2 GS operations, and any 

potential impact of tracers on human health or ecosystems as they relate to 

USDWs. 

IOGCC Response: Adequate down hole monitoring above the containment zone should 

in most cases eliminate the need for tracer systems to detect the presence 

of injected CO2 at the surface. Use of such tracers should not be required 

although should be an optional methodology for use at Director discretion. 

Individual Response: EPA agrees that the use of tracers should not be required at all GS sites, 

but should be available as an option. For this reason, EPA does not require the use of tracers at 

all GS sites; however, the Director has discretion to require their use if he/she determines that the 

use of tracers could improve monitoring of the site and enhance USDW protection from 

18
endangerment. The rule will also allow their use if proposed by the owner or operator and 

approved by the Director. 

While the intent of the GS regulations is to prevent leaks of CO2 to USDWs, EPA clarifies that 

all of the protective components of the regulation, including a comprehensive monitoring 

program per §146.90 (which includes testing of the well, ground water quality monitoring, and 

tracking of the CO2 plume and pressure front) support a multi-barrier approach to protecting 

USDWs. Additionally, some studies (e.g., Phelps and Cole, 2008; Hovorka et al., 2004; 

McCallum et al., 2005) found that tracers can provide useful CO2 monitoring information at 

injection wells both at depth and at near-surface locations. At Frio, tracers enabled quantification 

of CO2 plume behavior and provided a technique for model validity testing (McCallum et al., 

2005). EPA will continue to track research related to tracer use. The Agency plans to, every six 

years, collect and review data on GS projects to determine whether the appropriate amount and 

types of information and appropriate documentation are being collected, and to determine if 

modifications to the requirements are appropriate or necessary. 

Letter ID: 0263 Comment ID: 22814 Letter Lines: 376 to 382 

Comment Code: 4500 2.5 Proposed Mechanical Integrity Testing (MIT) Requirements (40 CFR 

146.89) 

Comment: III A. 5 Proposed Mechanical Integrity Testing Requirements 

CC. EPA requests comment on the practicability of this requirement. 

IOGCC Response: The IOGCC believes that the methodologies and requirements under 

Class II would be sufficient for Class VI wells and that applying Class I 

requirements is too stringent. 

Individual Response: EPA disagrees that the MIT requirements for Class VI wells are 

excessive. MITs are a long-standing and proven method of providing early warning of potential 

problems in the injection well system before they lead to leakage and/or endangerment of 

USDWs. 

Given the unique nature of CO2 injection for GS (i.e., the potential corrosivity of CO2 in the 

presence of water and impurities on well materials, the potential geomechanical impacts to well 

integrity due to CO2 phase changes, the temperature and pressure effects associated with 

injecting supercritical CO2, and the buoyant nature of CO2 and the potential for its movement up 

a wellbore), EPA believes it is important to protect USDWs from endangerment by adopting 

MIT requirements that are tailored to CO2 injection for GS. 

A comprehensive review conducted by EPA of MIT results from 1993 to 1998 found that Class I 

wells injecting corrosive fluids fail MITs at rates two to three times higher than those that inject 

non-corrosive fluids (USEPA 1999). Given the potential for CO2 to be corrosive (when in the 

presence of water or aqueous formation fluids), there is a potential risk factor for MIT failure 

and, for this reason, EPA believes that the tailored MIT requirements are appropriate. For 

additional information, please see the discussion of MITs in the final rule preamble. 

19
EPA acknowledges and agrees with the commenter that Class II well operators have decades of 

experience injecting CO2. However, EPA believes that significant operational differences 

between Class II wells and Class VI wells indicate that the Class II requirements are not 

sufficient to address the differences and that Class VI MIT requirements are, therefore, 

appropriate. For example, the volume of CO2 anticipated to be injected in Class VI wells is 

significantly greater than for Class II wells. Also, reservoir pressure conditions will be different 

with ER production (extraction) serving to reduce reservoir pressure for Class II operations while 

Class VI injection operations will have no comparable de-pressuring activities. For these reasons, 

EPA believes that injection of CO2 for GS projects differs significantly from that of Class II ER 

operations and warrants more frequent MITs to provide sufficient early warning of the potential 

for MI failures due to the corrosivity of the CO2 or reservoir pressure conditions associated with 

CO2 GS. 

EPA is using an adaptive approach to regulating GS. The Agency plans to collect and review 

data every six years on early GS projects, including MIT data, to determine whether the 

appropriate amount and types of information and appropriate documentation are being collected, 

and to determine if modifications to the requirements are appropriate or necessary. 

Letter ID: 0263 Comment ID: 22815 Letter Lines: 384 to 393 

Comment Code: 4546 2.5.2.2 MIT frequency (seeking comment) 

Comment: III A. 5 Proposed Mechanical Integrity Testing Requirements 

DD. EPA seeks comment on the appropriate frequency of internal and external MITs 

for GS injection wells, the appropriate types of MITs, and how to optimize 

MIT methods for GS. 

IOGCC Response: For internal MITs for GS injection wells, 5 years would be a 

sufficient frequency. For external MITs, the frequency should generally be annual 

depending upon the specific circumstances. The types softest should be those 

which are most appropriate under the specific circumstances. 

Individual Response: EPA disagrees that a five-year external MIT is appropriate. The final GS 

regulation retains the requirement that owners or operators of Class VI wells must demonstrate 

injection well external mechanical integrity at least once annually under §146.89(c). EPA 

believes this is justifiable for the protection of USDWs from endangerment given the unique 

nature of CO2 GS relative to other injection operations, including the potential corrosive impact 

of CO2 in the presence of water and impurities on well materials, the potential geomechanical 

impacts to well integrity due to CO2 phase changes, the temperature and pressure effects 

associated with injecting supercritical CO2, and the buoyant nature of the injected CO2. Because 

of the unknown long-term effects of CO2 GS, EPA chose a more conservative initial approach in 

the early stages of deployment for GS.. 

20
In addition, a comprehensive review conducted by EPA of MIT results from 1993 to 1998 found 

that Class I wells injecting corrosive fluids fail MITs at rates two to three times higher than those 

that inject non-corrosive fluids (USEPA 1999). Given the potential for CO2 to be corrosive (e.g., 

in the presence of water or aqueous formation fluids), there is a potential risk factor for MIT 

failure and, for this reason, EPA believes that the tailored MIT requirements in the final GS rule 

are appropriate. 

EPA believes that the MITs described in §146.89(c) of the rule (e.g., an approved tracer log or 

temperature or noise logs) are effective methods to demonstrate external MI, provide an 

important early warning of potential problems in the injection well system, and represent 

standard techniques that have been used successfully by the drilling industry and for the UIC 

Program for decades. EPA adds that the GS rule affords owners or operators the flexibility to 

choose appropriate MITs by requiring the owner or operator to prepare and gain approval for a 

project-specific testing and monitoring plan that includes MITs under §146.90. Owners or 

operators should develop a plan that is appropriate to the well’s design and construction; the 

Director will evaluate the plan based on construction plans submitted with the permit application. 

EPA clarifies that the regulations provides the Director discretion to require additional methods 

or, with the Administrator's approval, to approve the use of alternative MIT methods based on 

specific information about the site or the well. See §146.89(e). 

EPA adds that it is using an adaptive approach to regulating GS. The Agency plans to collect and 

review data every six years on GS projects, including MIT data, to determine whether the 

appropriate amount and types of information and appropriate documentation are being collected, 

and to determine if modifications to the requirements are appropriate or necessary. 

Letter ID: 0263 Comment ID: 22816 Letter Lines: 395 to 402 

Comment Code: 4650 2.6.5 CO2 plume and pressure front tracking (seeking comment) 

Comment: III A. 6 Proposed Plume and Pressure Front Monitoring Requirements 

EE. EPA seeks comment on the requirement for monitoring of GS sites for the purpose 

of tracking the location of the CO2 plume and associated pressure front over time. 

IOGCC Response: The IOGCC suggests that the operator be required to conduct 

ongoing monitoring. The frequency of reporting to the regulatory agency should be 

flexible depending upon site characteristics. 

Individual Response: The final rule (at §146.90(g)) requires owners or operators to perform 

monitoring to track the extent of the CO2 plume and pressure front. The owner or operator must 

use direct methods to monitor for pressure changes in the injection zone. Indirect methods (e.g., 

seismic, electrical, gravity, or electromagnetic surveys and/or down-hole CO2 detection tools) 

are required unless the Director determines, based on site-specific geology that such methods are 

not appropriate. 

21
EPA clarifies that the specifics of this monitoring must be described in the site-specific testing 

and monitoring plan, which must be approved by the Director. EPA believes that this approach 

provides flexibility to develop a site-specific monitoring plan, ensures that direct monitoring is 

available to track the movement of the CO2 and validate models, and recognizes that indirect 

techniques are not appropriate in all situations. The owner or operator's approved testing and 

monitoring plan will include the site-specific details, technologies, testing and monitoring 

frequencies, and other pertinent information. 

Letter ID: 0263 Comment ID: 22817 Letter Lines: 404 to 410 

Comment Code: 4640 2.6.4 Pressure fall-off testing (seeking comment) 

Comment: III A. 6 Proposed Plume and Pressure Front Monitoring Requirements 

FF. EPA seeks comment on the use and frequency of pressure fall-off testing for GS 

wells. 

IOGCC Response: The IOGCC does not see the necessity of pressure fall off testing 

for GS wells. It should be used as necessary but not mandated. 

Individual Response: EPA disagrees and believes that pressure fall-off testing is necessary for 

GS wells to ensure the protection of USDWs. Pressure fall-off tests are designed to verify that 

modeled projections of reservoir pressure decline agree with measured pressure decline profiles. 

These tests can be useful in AoR calculations and reevaluations and may also indicate 

mischaracterization of site geology and the presence of leakage pathways. EPA therefore 

believes that pressure fall-off testing must be conducted at least once every five years, and the 

final GS regulation includes this requirement at §146.90(f). Pressure fall-off tests may be 

conducted in conjunction with other well performance tests (i.e., mechanical integrity testing) to 

ensure safe and effective operations. 

Letter ID: 0263 Comment ID: 22818 Letter Lines: 412 to 426 

Comment Code: 4650 2.6.5 CO2 plume and pressure front tracking (seeking comment) 

Comment Code: 4655 2.6.5.1 Plume tracking techniques/geophysical methods (seeking 

comment) 

Comment: III A. 6 Proposed Plume andPressure Front Monitoring Requirements 

GG. Based on information evaluated to date, EPA believes that tracking the plume 

and pressure front is an important companion step to address any uncertainties 

associated with initial AoR modeling and requests comment on this approach 

and more efficient alternatives that maybe used to track the plume and pressure 

front. 

22
IOGCC Response: Tracking of the CO2 plume and pressure front should be required. 

The methodology, however, should not be specified but determined on a site 

specific basis. The IOGCC agrees with the following EPA statement: "As such, 

allowing flexibility in choosing the plume tracking methods and other monitoring 

technologies may provide an appropriate balance between the protective nature 

of indirect monitoring and cost considerations, as well as allowing for the 

adoption of continuously advancing technology." 

Individual Response: EPA agrees with the comment and the final rule (at §146.90(g)) requires 

owners or operators to perform monitoring to track the extent of the CO2 plume and pressure 

front. The owner or operator must use direct methods to monitor for pressure changes in the 

injection zone. Indirect methods (e.g., seismic, electrical, gravity, or electromagnetic surveys 

and/or down-hole CO2 detection tools) are also required unless the Director determines, based 

on site-specific geology, that such methods are not appropriate. EPA clarifies that the specifics of 

this monitoring must be described in the site-specific testing and monitoring plan, which must be 

approved by the Director. 

EPA believes that this approach provides flexibility to develop a site-specific monitoring plan, 

ensures that direct monitoring is available to track the movement of the CO2 and validate 

models, and recognizes that indirect techniques are not appropriate in all situations. The owner or 

operator's approved testing and monitoring plan will include the site-specific details, 

technologies, testing and monitoring frequencies, and other pertinent information. 

Letter ID: 0263 Comment ID: 22819 Letter Lines: 428 to 437 

Comment Code: 4660 2.6.6 Geochemical monitoring 

Comment: III A. 6 Proposed Plume and Pressure Front Monitoring Requirements 

HH. EPA seeks comment on the appropriate amount and types of monitoring that 

should be conducted at a GS site. 

IOGCC Response: The IOGCC agrees that owners and operators should report semiannually on the characteristics of injection fluids, injection pressure, flow 

rate, temperature, volume and annular pressure, and on the results of MITs, 

ground water monitoring, and any required atmospheric/soil gas monitoring. The 

amount and types of monitoring to be required, however, should be site specific. 

Individual Response: EPA agrees that monitoring plans and methods need to be site-specific 

and believes that the monitoring requirements for GS sites at §146.90 provide an appropriate 

level of flexibility in structuring a testing and monitoring plan that protects USDWs from 

endangerment. The final regulation provides for flexibility in: 1) methodologies used to collect 

these data, 2) the spatial resolution at which the data should be collected, and 3) how often the 

data should be collected. The number and placement of monitoring wells will be based on sitespecific information such as the calculated AoR, injection rate and volume, site geology, baseline 

data, and the presence of artificial penetrations within the AoR. 

23
EPA adds that the final rule, at §146.91(a) requires that owners and operators report semiannually on operating data and some monitoring data. See the preamble to the final rule for 

additional information. 

EPA is developing guidance on testing and monitoring to assist owners or operators and 

Directors in evaluating requirements under §146.90, including proposed monitoring plans. The 

guidance describes available technologies and recommended approaches for implementing a 

testing and monitoring plan, including pre-operational geophysical logging and testing of 

injection wells, MITs, injection well testing during operation, groundwater quality monitoring, 

tracking the CO2 plume and pressure front, and soil gas and surface air monitoring which may 

be required by the UIC Director for specific GS projects. The guidance can be found on EPA’s 

website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Letter ID: 0263 Comment ID: 22820 Letter Lines: 450 to 456 

Comment Code: 4610 2.6.1 Testing and monitoring plan requirement (seeking comment) 

Comment: III A. 6 Proposed Plume andPressure Front Monitoring Requirements 

JJ. In addition, EPA seeks comment regarding the use of a Director-approved 

monitoring plan for GS sites. 

IOGCC Response: The Director should be given flexibility to approve 

site specific monitoring plans as proposed in the IOGCC model regulations. 

Individual Response: EPA agrees with commenters that developing and following testing and 

monitoring plans and giving Directors flexibility to approve the plans based on site-specific 

criteria are important parts of assuring that a GS project is operating properly and is crucial for 

the early detection of potential endangerment to USDWs. 

The testing and monitoring plan is developed by the owner or operator in consultation with the 

Director and is designed to ensure that a detailed, Director-approved document describing how 

monitoring will be conducted during the lifetime of the project exists. EPA is developing 

guidance on testing and monitoring to assist owners or operators and Directors in evaluating 

requirements under §146.90, including proposed monitoring plans. The guidance describes 

available technologies and recommended approaches for implementing a testing and monitoring 

plan, including pre-operational geophysical logging and testing of injection wells, MITs, 

injection well testing during operation, groundwater quality monitoring, tracking the CO2 plume 

and pressure front, and soil gas and surface air monitoring which may be required by the UIC 

Director for specific GS projects. The guidance can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Letter ID: 0263 Comment ID: 22821 Letter Lines: 458 to 465 

24
Comment Code: 4710 2.7.1 Proposed submissions required for permit applications (seeking 

comment) 

Comment: III A. 7 Proposed Recordkeeping and Reporting Requirements 

KK. EPA seeks comment on the merits of requiring plans for monitoring, AoR, 

and post-injection site care as part of a permit application. 

IOGCC Response: Yes, there should be detailed monitoring, AoR, and post-injection 

site care plans as a part of the permit consistent with the recommendations of the 

IOGCC modelregulations. 

Individual Response: EPA agrees that incorporating the plans into the permit rather than 

establishing specific requirements for corrective action, monitoring, injection well plugging, and 

post-injection site care in the regulation provide the appropriate flexibility to address the variety 

of site-specific conditions that may be encountered at GS sites. 

EPA also believes that it is appropriate to require owners and operators to submit all plans, 

including the injection well plugging and post-injection site care and site closure plans, at the 

time of permit application. The owner or operator must demonstrate to the Director a satisfactory 

level of assurance that the they have planned for these events before injection commences and 

that they have ensured that appropriate financial resources are available to fund all required 

activities, as required at §146.85. The final rule retains requirements for submitting these plans 

with the permit application at §146.82(a). EPA expects that the requirement for this and other 

plans associated with GS projects will promote an ongoing dialogue between the owner or 

operator and the Director to ensure USDWs are protected from endangerment. Please see the 

final rule and the discussion of GS project plans in the preamble for additional information. 

Letter ID: 0263 Comment ID: 22822 Letter Lines: 467 to 474 

Comment Code: 4760 2.7.6 Proposed reporting frequency (seeking comment) 

Comment: III A. 7 Proposed Recordkeeping and Reporting Requirements 

LL. EPA seeks comment on the frequency of all proposed reporting requirements. 

IOGCC Response: As concerns the frequency of reporting for the physical and 

chemical characteristics of the injected fluids in a Class VI well, IOGCC 

model regulations specified annual reporting although semiannual reporting (as 

proposed by EPA in the rule) would be acceptable. 

Individual Response: EPA is retaining the semi-annual reporting requirements as proposed at 

§146.91(a). These requirements ensure the Director has the information needed to take 

preventive action in a timely manner to protect USDWs from endangerment. For additional 

information, please see the final rule and the preamble for a discussion of EPA's final approach 

to recordkeeping and reporting. 

25
Letter ID: 0263 Comment ID: 22823 Letter Lines: 476 to 484 

Comment Code: 4740 2.7.4 Electronic reporting (seeking comment) 

Comment: III A. 7 Proposed Recordkeeping andReporting Requirements 

MM. EPA seeks comment on the requirement for electronic reporting in today's 

proposed rule. 

IOGCC Response: The IOGCC agrees with electronic submittal in principle as long as 

there is sufficient flexibility to allow states to utilize existing or preferred 

state data processing systems or software. Electronic reporting should be an 

option but not a requirement. 

Individual Response: EPA believes that electronic formatting is the most appropriate format for 

submitting Class VI project information to the Director, and based on comments received on the 

proposed rule, the majority of Class VI well owners or operators will have the capability to 

report electronically, and requires this at §146.91(e). 

Acknowledging that some States may have to develop electronic data systems to receive 

electronic information from the owner or operator, and that many States which already have 

electronic data systems will have to make changes to accommodate a new class of UIC well 

(Class VI), EPA believes that it is prudent to provide assistance by developing a central 

framework for the electronic system that will be used by States to gather and track owner or 

operator data. This will enable owners or operators to submit data without having to wait for a 

State to develop a system. It will also provide for standardized submissions across the country 

and enable States to focus State resources on reviewing and approving permit applications rather 

than building or upgrading separate, independent databases for GS information. 

EPA is developing guidance for states that describes the recordkeeping, reporting, and additional 

data management needs associated with GS activities and provides recommended guidelines on 

the types of data to be collected for tracking GS projects, reporting to EPA for compliance 

tracking, and transfer of data to EPA's GS data system. The recordkeeping and reporting 

guidance will be available on EPA's web site, at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Letter ID: 0263 Comment ID: 22824 Letter Lines: 486 to 495 

Comment Code: 4750 2.7.5 Comments on the merit of annual reports (seeking comment) 

Comment Code: 4760 2.7.6 Proposed reporting frequency (seeking comment) 

Comment: III A. 7 Proposed Recordkeeping and Reporting Requirements 

NN. Although EPA has not included a requirement for this report in today's 

proposal, EPA seeks comment regarding the necessity for such an annual report. 

26
IOGCC Response: The IOGCC suggests that there be only one frequency of reporting, 

either annual or semi-annual. Thus, this requirement should be incorporated into 

the semi-annual reporting requirement enunciated by EPA in the rule for the 

physical and chemical characteristics of the injected fluids in a Class VI well. 

There should not be two different data reporting timeframe. 

Individual Response: EPA is retaining the semi-annual reporting requirements as proposed at 

§146.91(a). These requirements ensure the Director has the information needed to take 

preventive action in a timely manner to protect USDWs from endangerment. 

The final GS regulation does not include a requirement for an annual report. Instead, EPA 

believes that periodic reevaluation of the AoR, as required at §146.84(e), along with any 

revisions to the required plans that may be required based on the AoR reevaluation, will promote 

an ongoing relationship between the permitting authority and the owner or operator. The final 

GS rule, at §§146.84(c), 146.90(j), and 146.94(d), requires owners or operators to review and 

update the AoR and corrective action plan, the testing and monitoring plan, and the emergency 

and remedial response plan throughout the life of the project. Owners or operators must review 

each plan and identify necessary amendments to the plan or demonstrate to the Director that no 

amendment is needed. These reviews must be performed within one year of an AoR 

reevaluation, following any significant changes to the facility (e.g., the addition of monitoring or 

injection wells), or when required by the Director. In no case can reviews occur less often than 

once every five years. 

For additional information, please see the final rule and the preamble for a discussion of EPA's 

final approach to recordkeeping and reporting. 

As described above, EPA is retaining the semi-annual reporting requirements as proposed at 

§146.91(a). These requirements ensure the Director has the information needed to take 

preventive action in a timely manner to protect USDWs from endangerment. EPA notes that 

operators who want to streamline their reporting schedules can negotiate with the permitting 

authority to establish a schedule that allows reporting on all wells in a GS project at the same 

time; however, data for each well must be reported separately and at least as frequently as 

required at §146.91. For additional information, please see the final rule and the preamble for a 

discussion of EPA's final approach to recordkeeping and reporting. 

Letter ID: 0263 Comment ID: 22825 Letter Lines: 497 to 542 

Comment Code: 5240 2.8.2.2 Post injection timeframe (seeking comment) 

Comment Code: 5260 2.8.2.3 Adjusting the post-injection timeframe (seeking comment) 

Comment: III A. 8 Proposed Well Plugging, Post-Injection site Care, and Site Closure 

Requirements 

00. EPA requests comment on the proposed use of a tentative 50-year fixed timeframe 

that could be modified at the Director's discretion based on monitoring and 

27
modeling data. 

IOGCC Response: Given that current injection and reservoir behavior data 

demonstrates a decreasing risk of leakage after injection ceases, the IOGCC has 

concluded that a 50 year fixed timeframe is both unnecessary and too long. What 

is absolutely critical here is that the Director has discretion to increase or 

decrease the period based on the specifics of a particular project. In the view 

of the IOGCC, it would be better to prescribe a shorter period with discretion to 

go longer, rather than vice versa, as such would better facilitate project 

planning. 

III A. 8 Proposed Well Plugging, Post-Injection site Care, and Site Closure 

Requirements 

PP. EPA is requesting comments on the proposed requirements for well plugging, 

post-injection site care, and site closure, including the proposed requirements 

for the post-injection time period. 

IOGCC Response: Given documented evidence to date that there is a decreasing risk 

of leakage after injection ceases, The IOGCC has concluded that a 50 year fixed 

timeframe is both unnecessary and too long. What is absolutely critical here is 

that there be Director discretion to increase or decrease the period based on 

the specifics of a particular project. In the view of the IOGCC, it would be 

better to prescribe a shorter period with discretion to go longer, rather than 

vice versa, as such would better facilitate project planning. 

III A. 8 Proposed Well Plugging, Post-Injection site Care, and Site Closure 

Requirements 

QQ. In addition, EPA seeks comment on whether the Director should be allowed to 

shorten the timeframe based on performance information, and whether EPA should 

require a shorter or longer post-injection period if data suggests the time frame 

should be adjusted. 

IOGCC Response: Given documented evidence to date that there is a decreasing risk 

of leakage after injection ceases, The IOGCC has concluded that a 50 year fixed 

timeframe is both unnecessary and too long. What is absolutely critical here is 

that there be Director discretion to increase or decrease the period based on 

the specifics of a particular project. In the view of the IOGCC, it would be 

better to prescribe a shorter period with discretion to go longer, rather than 

vice versa, as such would better facilitate project planning. 

Individual Response: EPA disagrees that a post-injection site care timeframe of 50 years is 

excessive or unnecessary for most GS sites. EPA proposed a default post-injection site care 

timeframe of 50 years based on a review of research studies, industry reports, and existing 

environmental programs. This analysis was included in an EPA-prepared background document 

28
that is available in the federal docket, titled "Computational Modeling of Underground Injection 

of Carbon Dioxide for Determination of Area-of-Review and Potential Risk to Underground 

Sources of Drinking Water." EPA assessed various default timeframes based on additional 

review of research studies and evaluation of public comments. While numerous commenters 

suggested that EPA shorten the monitoring timeframe, none of the commenters provided 

sufficient data or other evidence to warrant a change in the proposed timeframe. While the 10- or 

30-year timeframe suggested by some of these commenters may be within the timeframe 

suggested in some studies, EPA believes that the potential risks of endangering USDWs will 

likely not decline within these timeframes and available data, including data submitted by 

commenters, do not support a different default timeframe. However, EPA recognizes that 

alternative timeframes may be appropriate under limited, specific circumstances. 

For this reason, the GS rule offers owners or operators flexibility regarding the duration of the 

PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC 

timeframe during the post-injection period based on site-specific data, pursuant to requirements 

at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator 

to demonstrate, during the permitting process based on substantial data, that an alternative PISC 

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to 

requirements at §146.93(c). 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to 

adjust the timeframe for a limited number of GS projects during the permitting process where 

substantial data exists to demonstrate that an alternative timeframe would be protective of 

USDWs, or based on data collected during the PISC period, is appropriate to address the range of 

sites where GS is anticipated to occur, to accommodate site-specific circumstances and various 

geologic conditions, and addresses commenters’ concerns, while ensuring USDW protection. 

Both approaches will utilize site-specific data, and be based on pressure monitoring and USDW 

impacts. 

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe 

for post-injection site care will be necessary in all but a limited number of cases. This default 50 

year post-injection site care timeframe represents a reasonable and protective monitoring period 

based on a review of research studies, industry reports, and existing environmental programs, 

and evaluation of public comments. 

Letter ID: 0263 Comment ID: 22826 Letter Lines: 544 to 562 

Comment Code: 5432 2.9.1.1 Need to adjust financial responsibility mechanisms (seeking 

comment) 

Comment: III A. 9 Proposed Financial Responsibility and Long-Term Care Requirements 

RR. EPA is requesting comments on whether financial responsibility mechanisms to 

be recommended in EPA guidance should be adjusted in the manner described, whether 

additional instruments should be included, and whether other adjustments to the 

financial responsibility mechanisms should be considered, all subject to EPA's 

29
authority under the SDWA. 

IOGCC Response: The EPA proposed rule for well financial assurance appears 

comprehensive enough. However, the proposed two-tier bond system of pre and post 

plugging of the well would be administratively cumbersome and the IOGCC would 

recommend one bond that covers operational, eventual plugging and post site 

remediation until the release date. 

The IOGCC model regulations proposed that in addition to well bonds that there also 

be an overall facility bond. The purpose of the facility bond would be to insure 

financial responsibility to address and mitigate non-well specific issues. What 

EPA is suggesting in the rule needs to be supplemented by the states via 

mechanisms such as a facility bond. 

Individual Response: EPA will allow owners or operators to demonstrate that §146.85(a) is met 

by using separate and multiple financial responsibility instruments for different GS activities. 

However, owners or operators must demonstrate adequate financial responsibility for all required 

activities with their permit application per §146.82(a)(14). 

EPA is developing guidance on financial responsibility for Class VI wells to assist owners or 

operators in evaluating the financial responsibility requirements for Class VI wells. EPA will 

describe the types of financial instruments that owners or operators can use to meet the financial 

responsibility requirements for GS wells. This guidance will be available on EPA's website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

To the suggestion that EPA require an overall "facility bond," EPA clarifies that the financial 

responsibility requirements are limited to covering activities associated with the injection. If the 

commenter refers to USDW endangerment that is related to the project but not necessarily the 

injection well, EPA notes that sufficient financial resources must be set aside to address the 

possibility of an emergency or remedial response in order to prevent endangerment of USDWs. 

Financial responsibility to address activities not associated with the endangerment of USDWs is 

outside of the scope of this rulemaking. 

EPA clarifies that the financial instrument the owner or operator provided to meet the 

requirements under §146.85 will be released when the phase of the project for which the 

instrument was required is complete and all financial obligations for that instrument have been 

met, pursuant to §146.85(b)(2) and §146.93. 

Letter ID: 0263 Comment ID: 22827 Letter Lines: 564 to 574 

Comment Code: 5432 2.9.1.1 Need to adjust financial responsibility mechanisms (seeking 

comment) 

Comment: III A. 9 Proposed Financial Responsibility and Long-Term Care Requirements 

SS. The Agency is also requesting comment on allowing separate financial 

30
demonstrations to be submitted for the plugging of the injection well and for the 

post-injection site care requirements. 

IOGCC Response: The IOGCC model regulations proposed that in addition to well 

bonds that there also be an overall facility bond. The purpose of the facility 

bond would be to insure financial responsibility to address and mitigate nonwell specific issues. What EPA is suggesting in the rule needs to be supplemented 

by the states via mechanisms such as a facility bond. 

Individual Response: To the suggestion that EPA require an overall "facility bond," EPA 

clarifies that the financial responsibility requirements are limited to covering activities associated 

with the injection. If the commenter refers to USDW endangerment that is related to the project 

but not necessarily the injection well, EPA notes that sufficient financial resources must be set 

aside to address the possibility of an emergency or remedial response in order to prevent 

endangerment of USDWs. Financial responsibility to address activities not associated with the 

endangerment of USDWs is outside of the scope of this rulemaking scope. 

Letter ID: 0263 Comment ID: 22828 Letter Lines: 576 to 589 

Comment Code: 5520 2.10.1 Appropriateness of existing public participation requirements 

(Part 25 and Part 124) for GS (seeking comment) 

Comment: IV. How Should UIC Program Directors Involve the Public In Permitting Decisions 

for GS Projects? 

TT. EPA requests comment on adopting the existing requirements for public 

participation at 40 CFRPart 25 and 40 CFRPart 124 and whether additional 

requirements should be included to reflect the availability of new tools for 

disseminating and gathering information. Such tools include cable networks, the 

Internet, and other new technology. 

IOGCC Response: All states have public notice laws and regulations that cover 

most regulatory and permitting functions. These laws and regulations would 

extend to the permitting and the regulation of GS that require public notice, 

hearings and due process to all affected parties. This should be adequate for 

public involvement purposes. 

Individual Response: EPA does not require the use of any new information technologies to 

inform the public, but encourages GS project operators and permitting authorities to use the 

Internet as well as both new and established tools to explain and post information on the latest 

developments. This information may include schedules for hearings, briefings, and other 

opportunities for involvement. EPA plans to conduct outreach on the GS rule, and provides GS 

related information on its website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. EPA currently uses social 

networking applications for important information (e.g., Facebook and Twitter), and will 

encourage GS operators and permitting authorities to use similar technologies to keep the public 

31
informed of GS projects. If states have applicable public participation requirements, these would 

need to be met as well. 

EPA believes that the existing UIC public participation requirements as specified in 40 CFR 25 

and 40 CFR 124 are appropriate for GS projects. In addition, because of the unique nature of GS 

projects, and the anticipated level of public interest in GS projects, EPA encourages early public 

involvement in GS projects. Providing the public with accurate, project specific information in 

the early stages of each GS project can help clarify project details and avoid public 

misperceptions about the nature and safety of GS projects, and will allow a potential GS owner 

or operator and the permitting agency to address the public's concerns before the permitting 

process is complete. 

EPA understands that public notice laws and regulations vary from state to state. EPA would like 

to clarify that in order for a state to receive primacy for Class VI GS wells their public notice 

requirements for permits must be at least as stringent as those required under 40 CFR Part 124. 

This requirement should provide a level uniformity between primacy states for purposes of 

providing public notice for GS wells. 

Letter ID: 0263 Comment ID: 22829 Letter Lines: 591 to 602 

Comment Code: 5560 2.10.3 Enhancing the public participation process (seeking comment) 

Comment: IV. How Should UIC Program Directors Involve the Public In Permitting Decisions 

for 

GS Projects? 

UU. EPA also requests comment on ways to enhance the public participation process, 

including engaging communities in the site characterization process as soon as 

candidate locations are identified. 

IOGCC Response: All states have public notice laws and regulations that cover 

most regulatory and permitting functions. These laws and regulations would 

extend to the permitting and the regulation of GS that require public notice, 

hearings and due process to all affected parties. This should be adequate for 

public involvement purposes. 

Individual Response: EPA disagrees with the commenter and believes that the existing UIC 

public participation requirements as specified in 40 CFR 25 and 40 CFR 124 are appropriate for 

GS projects. GS permitting authorities must follow the existing public participation requirements 

for UIC permits as specified in 40 CFR Part 124. These regulations lay out the procedures for 

decision making and include requirements such as requiring the Director to notify the public 

regarding the availability of the draft permit and allow him or her to require a public hearing on 

the draft permit. 

EPA notes that administrative procedure laws vary by state. States will describe their public 

32
participation activities in their primacy applications and must be at least as stringent as those 

provided under Parts 145 and 146. 

In addition, because of the unique nature of GS projects, and the anticipated level of public 

interest in GS projects, EPA encourages early public involvement in GS projects. Providing the 

public with accurate, project specific information in the early stages of each GS project can help 

clarify project details and avoid public misperceptions about the nature and safety of GS 

projects, and will allow a potential GS owner or operator and the permitting agency to address 

the public's concerns before the permitting process is complete. 

Letter ID: 0263 Comment ID: 22830 Letter Lines: 604 to 612 

Comment Code: 5610 2.11.1 Allowing partial primacy for Class VI wells (seeking comment) 

Comment: V. How Will States, Territories, and Tribes Obtain UIC Program Primacy for Class 

VI Wells? 

VV. EPA is seeking comment on the merits and possible disadvantages of allowing 

primacy approval for Class VI wells independent of other well classes. 

IOGCC Response: The IOGCC strongly supports independent state primacy for Class 

VI. States should have the authority to designate which agency in the state can 

apply for and be granted primacy. 

Individual Response: EPA agrees with commenters that states should be allowed to obtain 

primacy for Class VI wells independently of other well classes, and will allow independent 

primacy for Class VI wells under §145.1(i) of the final GS rule. Given the potential for CCS 

(encompassing capture, transportation, and geologic sequestration) to be an important part of a 

national priority to address climate change, EPA believes that providing states the flexibility to 

obtain primacy for Class VI wells independently of other well classes can help foster effective 

management of CCS. EPA believes that allowing independent Class VI primacy may encourage 

states to take responsibility for implementation of Class VI regulations and provide for a more 

comprehensive approach to managing CCS projects by promoting the integration of GS activities 

under SDWA into a broader framework for managing CCS. Furthermore, GS operations involve 

ancillary activities (e.g., pipeline operations, pore space ownership, land use rights, and surface 

access) for which states can call upon other authorities that exist at the state level (but outside 

UIC authority) to provide a more comprehensive CCS management approach. 

EPA also believes that allowing states to apply only for Class VI primacy will shorten the 

primacy approval process for states. It is very important to note that this shift in policy allowing 

for Class VI primacy does not apply to any other well Class under Section 1422. EPA will 

continue to discourage applications for partial primacy for all other well types under Section 

1422. 

EPA clarifies that states should be able to obtain primacy for Class VI wells independent of other 

33
well classes provided they develop regulations that are at least as stringent as the minimum 

Federal requirements (e.g., permitting, inspection, operation, monitoring, and recordkeeping 

requirements) in the final GS rule. EPA believes that existing programs can adapt their expertise 

to the new requirements for Class VI wells and will be able to develop a primacy application for 

Class VI wells under section 1422 of SDWA and ensure that their GS programs integrate into 

national climate change priorities and protect USDWs from endangerment. 

EPA also clarifies that primacy is granted to a state, not to any agency within that state, and 

states are free to choose which agency will implement the Class VI program—for instance, an 

environmental quality protection agency (non-Class II) or the state's traditional oil and gas 

regulatory agency (Class II)—as long as the program meets the minimum Federal requirements 

for Class VI wells as required under section 1422 of SDWA. Some states administer their 

program for all injection well classes through a single agency, whereas other States elect to 

divide the program between agencies. For example, in most States, the Class II program is run by 

an oil and gas agency and other well classes are run by a State environmental agency (e.g., the 

Oklahoma Corporation Commission oversees Class II wells in the State, and the Oklahoma 

Department of Environmental Quality oversees other well classes). Additionally, several States 

allow their oil and gas agencies to administer their UIC program for specific well classes or 

subclasses provided they meet all Federal requirements (e.g., the Texas Railroad Commission 

oversees Class III brine-mining wells and Class V geothermal wells in Texas). EPA believes that 

retaining this flexibility for States to identify the appropriate agency to oversee Class VI wells 

will address commenters’ concerns that States should be afforded the opportunity to determine 

which agency should oversee Class VI wells, and recognizes the existing expertise of both State 

oil and gas agencies and environmental agencies. 

Letter ID: 0263 Comment ID: 22831 Letter Lines: 614 to 620 

Comment Code: 5700 2.12 Comments on the proposed duration of Class VI permits (seeking 

comment) 

Comment: VI. What Is the Proposed Duration of a Class VI Injection Permit? 

WW. Therefore, EPA proposes that Class VI injection well permits would be issued 

for the operating life of the GS project including the post-injection site care 

period. EPA seeks comment on the merits of this approach. 

IOGCC Response: The IOGCC agrees with the EPA proposal. 

Individual Response: The final rule maintains the lifetime permit provision and clarifies that the 

permit extends through the post-injection site care period (144.36(a)). It also adds a requirement 

that the Director review each Class VI permit at least once every 5 years to determine whether it 

should be modified, revoked and reissued, terminated or a minor modification made as provided 

in §§144.39, 144.40, or 144.41. The Director’s review will be informed by the owners’ or 

operators’ iterative reevaluation of the project. Specifically, the final rule includes a requirement 

that the AoR be reevaluated at least every five years, and also requires owners or operators to 

34
review and update the AoR and corrective action plan, the testing and monitoring plan, and the 

emergency and remedial response plan throughout the life of the project (146.84(e), 146.90(j), 

and 146.94(d)). Owners or operators must review each plan and identify necessary amendments 

or demonstrate to the Director that no amendment is needed. In no case can reviews occur less 

often than once every five years. The iterative process and subsequent plan reevaluations ensure 

that time and resources are committed to the most critical aspects of the permit in preventing 

endangerment to USDWs. EPA believes that the iterative process of developing and executing 

the various plans required of GS well operators in the final rule (e.g., for AoR and corrective 

action, testing and monitoring, injection well plugging, post-injection site care, and emergency 

and remedial response) is tailored to the unique aspects of—and is more appropriate for–GS than 

establishing a finite permit duration (e.g., ten years as suggested by some commenters). 

Letter ID: 0263 Comment ID: 24960 Letter Lines: 130 to 136 

Comment Code: 1630 1.3.3 RCRA/hazardous waste issues (seeking comment) 

Comment: II . I. Is Injected CO2 Considered a Hazardous Waste Under RCRA? 

H. EPA seeks comment on this approach and other considerations associated with 

the presence of impurities in the CO2 stream. 

IOGCC Response: Injected CO2 is not and should not be considered a hazardous 

waste or regulated under RCRA or CERCLA. It is assumed that RCRA or CERCLA wastes 

Individual Response: EPA recognizes that many CO2 streams may be relatively pure, and 

research indicates that the estimated amounts of impurities in a CO2 stream are likely to be low. 

However, these estimates are based on limited information, and uncertainties remain about the 

expected concentrations of impurities from the various types of CO2 streams. 

With respect to RCRA, EPA received many comments regarding the applicability of the RCRA 

regulations and statute to CO2 streams that are geologically sequestered under the final Class VI 

UIC well requirements. As a result, EPA has decided to initiate a separate proposed rulemaking 

specifically to examine the issue of RCRA applicability to CO2 streams being geologically 

sequestered, including the possible option of a conditional exemption from the RCRA 

requirements for CO2 GS in Class VI wells. EPA will consider these comments as part of its 

development of that proposal. The Agency will consider issues particular to RCRA in the context 

of that separate rulemaking, and recommends that the commenter read that proposed rule when it 

is published. The Agency notes that commenters who wish to submit comments on the RCRA 

proposal will need to do so during the comment period for that rule. Finally, EPA also notes that 

the final GS rule, which adds new regulations for Class VI wells under the Safe Drinking Water 

Act (SDWA), is not making any changes to the RCRA regulations. 

Letter ID: 0263 Comment ID: 24961 Letter Lines: 139 to 147 

Comment Code: 1640 1.3.4 CERCLA issues (seeking comment) 

35
Comment: II. J. Is Injected CO2 Considered a Hazardous Substance Under CERCLA? 

1. EPA requests comment on particular situations where this might occur. EPA also 

requests comment on other considerations associated with the presence 

of impurities in the CO2 stream related to CERCLA. 

IOGCC Response: Injected CO2 is not and should not be considered a hazardous 

waste or regulated under RCRAor CERCLA. It is assumed that RCRA or CERCLA wastes 

would be removed from the CO2 stream prior to storage. 

Individual Response: CO2 itself is not listed as a hazardous substance under CERCLA 

however, the CO2 stream may contain a listed hazardous substance (such as mercury) or may 

mobilize substances in the subsurface that could react with ground water to produce listed 

hazardous substances (such as sulfuric acid). Whether such substances may result in CERCLA 

liability from a sequestration facility depends entirely on the composition of the specific CO2 

stream and the environmental media in which it is stored (e.g., soil or ground water). CERCLA 

exempts from liability, under CERCLA section 107, 42 U.S.C. 9607, certain “federally permitted 

releases” as defined in CERCLA, 42 U.S.C. 9601(10). Class VI permits will need to be carefully 

structured to ensure that they prevent potential releases from the well which are outside the scope 

of the Class VI permit. 

With respect to the commenter’s reference to RCRA, EPA received many comments regarding 

the applicability of the RCRA regulations and statute to CO2 streams that are geologically 

sequestered under the final Class VI UIC well requirements. As a result, EPA has decided to 

initiate a separate proposed rulemaking specifically to examine the issue of RCRA applicability 

to CO2 streams being geologically sequestered, including the possible option of a conditional 

exemption from the RCRA requirements for CO2 GS in Class VI wells. EPA will consider these 

comments as part of its development of that proposal. The Agency will consider issues particular 

to RCRA in the context of that separate rulemaking, and recommends that the commenter read 

that proposed rule when it is published. The Agency notes that commenters who wish to submit 

comments on the RCRA proposal will need to do so during the comment period for that rule. 

Letter ID: 0263 Comment ID: 24962 Letter Lines: 439 to 448 

Comment Code: 4670 2.6.7 Surface air monitoring and/or soil gas monitoring (seeking 

comment) 

Comment: III A. 6 Proposed Plume and Pressure Front Monitoring Requirements 

11. Specifically, EPA seeks comment regarding the usefulness of indirect 

geophysical monitoring and surface air and soil gas monitoring. 

IOGCC Response: The IOGCC agrees that owners and operators should report semiannually on the characteristics of injection fluids, injection pressure, flow 

rate, temperature, volume and annular pressure, and on the results of MITs, ground 

36
37

water monitoring, and any required atmospheric/soil gas monitoring. The amount 

and types of monitoring to be required, however, should be site specific. 

Individual Response: EPA agrees that monitoring plans and methods need to be site-specific 

and believes that the monitoring requirements for GS sites at §146.90 provide an appropriate 

level of flexibility in structuring a testing and monitoring plan that protects USDWs from 

endangerment. The final regulation provides for flexibility in: 1) methodologies used to collect 

these data, 2) the spatial resolution at which the data should be collected, and 3) how often the 

data should be collected. The number and placement of monitoring wells will be based on sitespecific information such as the calculated AoR, injection rate and volume, site geology, baseline 

data, and the presence of artificial penetrations within the AoR. 

EPA adds that the final rule, at §146.91(a) requires that owners and operators report semiannually on operating data and some monitoring data. See the preamble to the final rule for 

additional information. 

EPA is developing guidance on testing and monitoring to assist owners or operators and 

Directors in evaluating requirements under §146.90, including proposed monitoring plans. The 

guidance describes available technologies and recommended approaches for implementing a 

testing and monitoring plan, including pre-operational geophysical logging and testing of 

injection wells, MITs, injection well testing during operation, groundwater quality monitoring, 

tracking the CO2 plume and pressure front, and soil gas and surface air monitoring which may 

be required by the UIC Director for specific GS projects. The guidance can be found on EPA’s 

website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.