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.
DUKE ENERGY CORPORATION 

526 South Church Street. 

Charlotte, NC 28202 

Mailing Address: 

PO Box 1006 

Charlotte, NC 28201-1006 

COMMENTS OF DUKE ENERGY 

ON THE ENVIRONMENTAL PROTECTION AGENCY’S 

PROPOSED RULEMAKING UNDER THE SAFE DRINKING WATER ACT’S 

UNDERGROUND INJECTION CONTROL PROGRAM FOR CARBON DIOXIDE 

GEOLOGIC SEQUESTRATION WELLS 

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

December 22, 2008 

Duke Energy Shared Services (“Duke Energy”), on behalf of Duke Energy Carolinas, 

LLC., Duke Energy Indiana, Inc., Duke Energy Ohio Inc., and Duke Energy Kentucky Inc. 

submits the following comments in response to the above-referenced proposed rule and request 

for comment from the Environmental Protection Agency (“EPA”). Duke Energy, one of the 

largest electric power companies in the United States, supplies and delivers electricity to 

approximately 4 million U.S. customers and natural gas service to approximately 520,000 

customers in its regulated jurisdictions. The company has approximately 35,000 net megawatts 

of electric generating capacity in the Midwest and the Carolinas, and natural gas distribution 

services in Ohio and Kentucky. In addition, Duke Energy has more than 4,000 net megawatts of 

electric generation in Latin America, and is a joint-venture partner in a U.S. real estate company. 

Duke Energy supports EPA’s efforts to develop a regulatory framework for geologic 

sequestration (“GS”) of carbon dioxide (“CO2”). Coal, the nation’s most abundant natural 

energy resource, accounts for approximately 50% of the electricity consumed in the U.S. today. 

Development of a workable GS regulatory program is critical to this country’s ability to make 

substantial reductions in CO2 emissions while keeping coal as a viable energy resource that 

contributes to the nation’s energy independence. 

As one of the largest coal-fired generators of electricity in the U.S., and as a likely user of 

GS to reduce CO2 emissions, this rulemaking will have a direct impact on Duke Energy and its 
2

customers. As an entity whose operations will be directly impacted by the rule, Duke Energy 

encourages EPA to provide as much flexibility as possible while maintaining appropriate 

environmental safeguards. For example, the characteristics of potential GS sites will be highly 

variable. EPA should provide flexibility by avoiding a one-size-fits-all approach. This can be 

done by incorporating performance-based standards into the final rule that would allow for sitespecific project design, monitoring and closure. Additionally, the technology associated with 

large scale injection and storage of CO2 associated with electricity generation is still developing. 

EPA should provide flexibility by designing the UIC program for GS of CO2 so the program 

requirements can evolve along with the technology over time rather than lock-in regulatory 

requirements that will likely become obsolete. 

 In addition to the following comments, Duke Energy supports the comments submitted 

by the Utility Solid Waste Activities Group, the Edison Electric Institute, the Electric Power 

Research Institute, and the Gasification Technologies Council. 

Specific Comments

Rule Must Provide Flexibility

The technologies described in the proposal will not likely be commercially deployed on a 

widespread basis for some time; therefore EPA’s rule must remain flexible in order to 

accommodate technological developments related to the GS of CO2 as they occur. It is also 

essential that performance-based standards be incorporated into the Final Rule to reflect the fact 

that the characteristics of GS sites will vary widely. The use of performance-based standards 

rather than a one-size-fits-all approach will result in better performing and more cost-effective 

projects because they will have been tailored to a specific site’s characteristics. 

The rule should not be made unnecessarily stringent by requiring detailed information for 

Class VI permit applications that may not be available during the early phases of the permit 

application process. A better approach would be to require the reporting of detailed information 

over time as it becomes available through operation of the well, site reevaluation, and corrective 

action.
3

RCRA and CERCLA Applicability

To encourage adoption and use of the Class VI wells by the regulated community EPA 

must resolve policy and legal issues regarding the applicability of RCRA and CERCLA 

regulation and liabilities to projects permitted and operated under the proposed rule. Subjecting 

any CO2 GS project to RCRA controls, and failure to adequately mitigate the potential for 

unlimited CERCLA liability will pose a serious obstacle to the commercial deployment of GS 

technology. 

Injection of CO2 into a Cass VI well should not be viewed as disposal of a waste subject 

to RCRA regulation. Alternative scenarios may involve temporary storage of a commodity, or 

containment of a material in an industrial process. If CO2 is deemed a waste under the rule, the 

current RCRA regulations and testing guidelines will need to be revised to address 

characterization of supercritical fluids. 

Injection of CO2 into vast areas underlying multiple political jurisdictions and surface 

properties owned by multiple parties was not anticipated when “Superfund liability” was initially 

conceived. Failure to address liability uncertainties via a permitted injection exemption or by a 

mechanism for transfer of long-term liability to government bodies will be a disincentive to 

commercial deployment of GS technology. 

Grandfathering Class I, Class II and Class V Injection Wells

Duke Energy supports EPA’s proposed provision allowing for the potential 

grandfathering of construction requirements for permitted Class I, Class II and Class V wells that 

request a Class VI permit for GS of CO2. Duke Energy also recommends that grandfathering be 

expanded beyond construction for Class V experimental CO2 injection wells. 

The permitting of experimental wells includes making a determination about the 

protection of underground sources of drinking water (“USDW”). Changing wells from 

experimental to regular injection of CO2 should not change the determination. Owners/operators 

of experimental wells that wish to have them reclassified as Class VI injection wells should be 

allowed to do so with minimal addition submittals. However, if the Director determines that 
4

conversion of a well to Class VI would endanger USDW, grandfathering should not be 

permitted. 

Duke Energy recognizes that there are differences between Class II and Class V wells. 

Class II wells are associated with enhanced oil and gas recovery. The strata that contained the 

oil and gas for millions of years should be good candidates for GS of CO2. While long term GS 

of CO2 was not the goal during the permitting of Class II wells, the Director should nonetheless 

consider grandfathering them for reclassification to Class VI wells. Owners/operators of Class 

II wells used for long-term GS of CO2 would still need to demonstrate that doing so would not 

pose a danger to USDW. Before a Class II well is permitted as a Class VI well, however, the 

owner/operator should be required to meet all other permitting requirements for a Class IV well. 

The construction requirements for Class I wells is very similar to what EPA proposes for 

Class VI wells. Duke Energy feels that once the integrity and stability of the well have been 

demonstrated in a CO2 rich environment by the owner/operator the construction of a Class I well 

should be grandfathered. As with Class II wells, all other requirements for a Class VI well 

would have to be met before an injection permit would be issued. 

Duke Energy recommends that the Final Rule allow permitted Class V experimental CO2

injection wells to be re-classified as Class VI wells based on initial permitting information unless 

the Director determines that the project would endanger USDWs. Class II wells should be 

considered for reclassification once all requirements for a Class VI well are met. Class I well 

construction should be grandfather upon demonstration that the well construction has and will 

maintain mechanical integrity while being used for GS of CO2. All other requirements of the 

final rule would apply for reclassification to Class VI. 

Reevaluation of Area of Review (“AoR”)

Current UIC regulations require the owner/operator of a proposed injection site to 

determine the AoR based on the area necessary to include the calculated cone of pressure 

influence. The amount of CO2 that will be injected at a GS site over the life of a project will be 

tens if not hundreds of millions of tons. This quantity of CO2 along with uncertain dispersion 
5

characteristics makes it next to impossible to determine the correct AoR utilizing a fixed radius 

or simple mathematical method. 

Acceptable methods for determining the AoR should include but not be limited to 

multiphase fluid flow models. It is anticipated that modeling will improve over time as 

experience with CO2 sequestration increases. Demonstration projects should not be constrained 

by allowing only the use of current models. Any model based on accepted science that has been 

validated should be acceptable. Models should be calibrated using actual site data once it 

becomes available. 

The AoR for a GS site for CO2 will be dynamic and in all probability irregular in shape. 

Based on the quantity of CO2 to be sequestered at a site, the AoR could be hundreds of square 

miles. A significant amount of time and money would be needed to complete an up-front 

evaluation of the life of a project AoR. A large portion of this effort could be wasted since the 

injection plumb may not travel as anticipated. As a result of this uncertainty, Duke Energy 

recommends a phased evaluation for the AoR. The AoR should be reviewed periodically (every 

ten years or as agreed upon by the Director). This would allow any necessary corrective actions 

to be focused where needed. This approach would allow projects to proceed more expeditiously, 

reduce start-up costs and because of the periodic review, provide greater protection to USDW. 

Transference between CO2 Sequestration Methods

Duke Energy recognizes that there are differences between Class II and Class VI wells. 

Class II wells are associated with enhanced oil and gas recovery which can be an avenue for CO2

sequestration. Aside from deep saline formations, other potential sequestration areas include 

coal seams (Enhanced Coal Bed Methane – ECBM), and shale layers. Since EPA’s proposed 

rule addresses CO2 volumes in millions of tons per year, Duke Energy recommends providing as 

much flexibility as possible when addressing potential CO2 sequestration areas so that the rules 

governing CO2 sequestration are fully transferable should more than one sequestration method be 

selected or should circumstances dictate a change from GS to the EOR market or vice versa. 

Duke Energy believes that allowing grandfathering of the proposed provisions to address this 
6

type of transfer should be allowed except when the Director determines that conversion of a well 

between Class II and Class VI would endanger USDW.

Injection Activities that Cross State Boundaries

In view of the likelihood that CO2 injection activities on GS projects will cross state 

boundaries, Duke Energy joins other stakeholders in urging EPA to reconsider its position of not 

addressing cross-state boundary issues in this rule-making. Instead, EPA should provide 

directives to states and corresponding certainty to owners and operators of GS projects when the 

AoR crosses state lines. At a minimum, the Final Rule should provide that the state in which the 

well head is located should be the primary state for purposes of permitting the Class VI well for 

GS of CO2. EPA should also direct the primary state to consult, coordinate and cooperate with 

each state within the AoR. The Final Rule should establish guidelines for the consultation, 

coordination and cooperation between the primary state and each state within the AoR. 

Financial Responsibility and Appropriate Risk Management Approaches

EPA is proposing a default time period of fifty years for post-injection activities. 

Although the proposed rules would gives the Director the discretion to adjust the default time 

period, such a provision will create tremendous uncertainty and impose unnecessary regulatory 

burden and cost on regulators. Protecting USDW and commercializing GS technology for CO2

would be better served by focusing on site characterization and a site-specific performance based 

approach to well closure that takes into consideration the particular needs of each CO2

sequestration site. In addition, a fifty-year default period could actually discourage owners or 

operators from undertaking proper site characterization and working to develop innovative ways 

to safety close wells in a shorter time period. It would also introduce significant financial 

uncertainty that could make actually obtaining necessary financial assurances difficult if not 

impossible. 

State Primacy

The proposed rule seeks comment on whether states should be permitted to seek primacy 

for Class VI wells, noting the Agency’s belief that “the most effective approach for the 
7

comprehensive management of CO2 GS projects would be achieved at the State and Tribal 

level.” Duke Energy believes it is appropriate to allow States to obtain primacy for only Class 

VI wells. States should play a key role in managing CO2 GS projects going forward, as they 

have with Class II wells for decades. The experience states have gained by regulating CO2

injection through the existing programs can offer many benefits in the context of Class VI wells. 

State regulators have familiarity with local environmental, geologic, and financial concerns, and 

in many cases have pre-existing relationships with the regulated community that can facilitate 

implementation of a new and complex regulatory program. Further, some states are moving 

ahead with developing their own legislation and regulations related to carbon capture and storage 

(“CCS”) activities—in many cases developing laws and rules that include unique provisions and 

provide incentives for the development of new CCS projects. Allowing those states to take on 

primacy for Class VI wells (in particular, allowing them to take on primacy for Class VI wells 

without assuming the regulatory burden that may be associated with other well classes) will help 

ensure that they are given credit and recognition for their groundbreaking work in this area. 

Conclusion

Duke Energy appreciates the opportunity to provide comments on this important 

rulemaking. Having a workable regulatory program in place for the geologic sequestration of 

CO2 is absolutely essential to this country’s ability to reduce greenhouse gas emissions at a 

reasonable cost and without eliminating coal as a viable energy resource. 
Letter ID: 0209 

Commenter: Michael Stroben 

Organization: Duke Energy 

Letter ID: 0209 Comment ID: 22676 Letter Lines: 34 to 40 

Comment Code: 1420 1.2.1.1 Support the GS rulemaking 

Comment: Duke Energy supports EPA’s efforts to develop a regulatory framework for 

geologic sequestration ("GS") of carbon dioxide ("CO2"). Coal, the nation’s most 

abundant natural energy resource, accounts for approximately 50% of the 

electricity consumed in the U.S. today. Development of a workable GS regulatory 

program is critical to this country’s ability to make substantial reductions in 

CO2 emissions while keeping coal as a viable energy resource that contributes to 

the nation’s energy independence. 

Individual Response: EPA believes that the creation of a new injection well class (VI) under the 

existing UIC Program is necessary to enable the use of GS as a climate change mitigation 

technology in a manner that protects USDWs from endangerment. EPA agrees that the UIC 

Program, under the authority of the SDWA, provides a strong framework for regulating injection 

of CO2 for GS and adds that the GS regulation tailors the UIC requirements to address the 

unique issues associated with large-scale GS including large injection volumes, the relative 

buoyancy of CO2, its corrosivity in the presence of water, the potential presence of impurities in 

captured CO2, and its mobility within subsurface geologic formations. 

Letter ID: 0209 Comment ID: 22677 Letter Lines: 42 to 55 ; 64 to 74 

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

Comment: As one of the largest coal-fired generators of electricity in the U.S., and as a 

likely user of GS to reduce CO2 emissions, this rulemaking will have a direct 

impact on Duke Energy and its customers. As an entity whose operations will be 

directly impacted by the rule, Duke Energy encourages EPA to provide as much 

flexibility as possible while maintaining appropriate environmental safeguards. 

For example, the characteristics of potential GS sites will be highly variable. 

EPA should provide flexibility by avoiding a one-size-fits-all approach. This 

can be done by incorporating performance-based standards into the final rule 

that would allow for site-specific project design, monitoring and closure. 

Additionally, the technology associated with large scale injection and storage 

of CO2 associated with electricity generation is still developing. EPA should 

provide flexibility by designing the UIC program for GS of CO2 so the program 

requirements can evolve along with the technology over time rather than lock-in 

regulatory requirements that will likely become obsolete. 

RULE MUST PROVIDE FLEXIBILITY 

1
The technologies described in the proposal will not likely be commercially 

deployed on a widespread basis for some time; therefore EPA’s rule must remain 

flexible in order to accommodate technological developments related to the GS of 

CO2 as they occur. It is also essential that performance-based standards be 

incorporated into the Final Rule to reflect the fact that the characteristics of 

GS sites will vary widely. The use of performance-based standards rather than a 

one-size-fits-all approach will result in better performing and more costeffective projects because they will have been tailored to a specific site’s 

characteristics. 

Individual Response: EPA believes that the Class VI requirements balance site-specific 

flexibility with USDW protection. Rather than setting performance or technology-based 

standards for GS projects, EPA is adopting a flexible approach, where operators of GS projects 

would develop and implement site-specific plans for delineating the AoR, testing and monitoring 

the site, performing corrective action, and post-injection site care. EPA believes that the plans—

which would be reviewed and approved by the Director and periodically updated throughout the 

life of the project—promote an ongoing dialogue between the operator and the Director that will 

encourage use of the most appropriate technologies for a particular project. 

To address the comment that the rule should accommodate future technological developments 

related to GS, EPA adds that it is using an adaptive approach to regulating GS under the UIC 

Program. Even after finalization of the GS regulation, EPA plans, every six years, to collect and 

review project data on GS research 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: 0209 Comment ID: 22678 Letter Lines: 57 to 60 

Comment Code: 1000 1. General and Administrative Comments 

Comment: In addition to the following comments, Duke Energy supports the comments 

submitted by the Utility Solid Waste Activities Group, the Edison Electric 

Institute, the Electric Power Research Institute, and the Gasification 

Technologies Council. 

Individual Response: EPA acknowledges the comment. Please see the remainder of EPA's 

responses to this comment and USWAG’s comment, Edison Electric Institute’s comment, 

Electric Power Research Institute’s comment, and the Gasification Technologies Council 

comment for further details. For additional information on EPA's final regulatory approach, 

please see the final rule and preamble as well as the rulemaking docket. 

Letter ID: 0209 Comment ID: 22679 Letter Lines: 76 to 81 

Comment Code: 4710 2.7.1 Proposed submissions required for permit applications (seeking 

2
comment) 

Comment: The rule should not be made unnecessarily stringent by requiring detailed 

information for Class VI permit applications that may not be available during 

the early phases of the permit application process. A better approach would be 

to require the reporting of detailed information over time as it becomes 

available through operation of the well, site reevaluation, and corrective 

action. 

Individual Response: EPA believes that the unique characteristics of CO2 injection (e.g., its 

relative buoyancy, the large volume that may be injected, or the potential for chemical 

interaction with the subsurface) warrant the additional information required to be submitted by 

GS operators under §146.82. These requirements are not unnecessarily stringent or burdensome. 

In order to protect USDWs from endangerment, Directors must have all the data they need to 

make well-informed decisions on establishing permit conditions and granting permits. 

In response to concerns that some data will not be available until the well has been drilled, EPA 

acknowledges that not all of the information listed at §146.82 of the proposed regulation will be 

available at the time the owner or operator develops the permit application. Based on comments 

and evaluation of the proposed requirements, EPA revised this subpart so that the final regulation 

specifies separate requirements for information to be submitted for approval with the permit 

application before well construction, as required at §146.82(a), and information to be submitted 

after the well is constructed; however all information must be submitted before injection is 

authorized, as required at §146.82(c). 

Letter ID: 0209 Comment ID: 22680 Letter Lines: 83 to 90 

Comment Code: 1630 1.3.3 RCRA/hazardous waste issues (seeking comment) 

Comment Code: 1640 1.3.4 CERCLA issues (seeking comment) 

Comment: RCRA AND CERCLA APPLICABILITY 

To encourage adoption and use of the Class VI wells by the regulated community 

EPA must resolve policy and legal issues regarding the applicability of RCRA and 

CERCLA Regulation and liabilities to projects permitted and operated under the 

proposed rule. Subjecting any CO2 GS project to RCRA controls, and failure to 

adequately mitigate the potential for unlimited CERCLA liability will pose a 

serious obstacle to the commercial deployment of GS technology. 

Individual Response: 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 

3
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: 0209 Comment ID: 22681 Letter Lines: 92 to 97 

Comment Code: 1630 1.3.3 RCRA/hazardous waste issues (seeking comment) 

Comment: Injection of CO2 into a Cass VI well should not be viewed as disposal of a waste 

subject to RCRA regulation. Alternative scenarios may involve temporary storage 

of a commodity, or containment of a material in an industrial process. If CO2 is 

deemed a waste under the rule, the current RCRA regulations and testing 

guidelines will need to be revised to address characterization of supercritical 

fluids. 

Individual Response: 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: 0209 Comment ID: 22682 Letter Lines: 99 to 104 

Comment Code: 1640 1.3.4 CERCLA issues (seeking comment) 

Comment: Injection of CO2 into vast areas underlying multiple political jurisdictions and 

surface properties owned by multiple parties was not anticipated when "Superfund 

liability" was initially conceived. Failure to address liability uncertainties 

via a permitted injection exemption or by a mechanism for transfer of long-term 

liability to government bodies will be a disincentive to commercial deployment 

of GS technology. 

Individual Response: CERCLA exempts from liability, under CERCLA section 107, 42 U.S.C. 

9607, certain “federally permitted releases” (FPR) as defined in CERCLA, 42 U.S.C. 9601(10). 

Therefore, Class VI requirements and permits will need to be carefully structured to ensure that 

they do not “authorize” inappropriate releases, and would need to prevent potential releases from 

4
the well which are outside the scope of the Class VI permit. 

Regarding long term liability, once an owner or operator has met all regulatory requirements 

under Part 146 for Class VI wells and the Director has approved site closure pursuant to 

requirements at §146.93, the owner or operator will generally no longer be subject to 

enforcement for regulatory noncompliance. Furthermore, their financial instrument as required 

under §146.85 will be released if it was not used. However, even if a site closure is approved 

under §146.93, an owner or operator may be held liable for regulatory noncompliance (including 

violation of 40 CFR 144.12) in certain circumstances. For example, an owner or operator may be 

held liable for regulatory noncompliance even after site closure was approved if the Director 

relied on erroneous information (e.g., erroneous modeling data) provided by the owner or 

operator when approving site closure. 

Separate from EPA’s authority to enforce regulatory compliance, an owner or operator may be 

subject to a §1431 response order even after proper site closure is approved under §146.93. 

Under §1431 the Administrator may require an owner or operator to take necessary response 

measures if he or she receives information that a contaminant is present or is likely to enter a 

public water system or an USDW, which may present an imminent and substantial endangerment 

to the health of persons, and the appropriate State and local authorities have not acted to protect 

the health of such persons. The action may include issuing administrative orders or commencing 

a civil action for appropriate relief against the owner or operator of a Class VI well. If the owner 

or operator fails to comply with the order, they may be subject to a civil penalty for each day in 

which such violation occurs or failure to comply continues. 

Furthermore, after site closure an owner or operator may remain liable under tort and other 

remedies, or under other federal statutes including, but not limited to, Clean Air Act, 42 U.S.C. 

§§7401-7671; CERCLA, 42 U.S.C. §9601-9675; and RCRA, 42 U.S.C. §6901-6992. EPA does 

not have authority to transfer SDWA or other legal liability for Class VI wells to the State or 

federal government or a third-party fund. See the final rule preamble for further discussion of 

EPA's final approach. 

EPA adds that promoting the use of GS is outside the scope of the GS rule. Rather, the purpose 

of the GS regulation is to ensure that, where deployed, GS is conducted in a manner that protects 

USDWs from endangerment. 

Letter ID: 0209 Comment ID: 22683 Letter Lines: 106 to 147 

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

Comment: GRANDFATHERING CLASS I, CLASS II AND CLASS V INJECTION WELLS 

Duke Energy supports EPA’s proposed provision allowing for the potential 

grandfathering of construction requirements for permitted Class I, Class II and 

Class V wells that request a class VI permit for GS of CO2. Duke Energy also 

recommends that grandfathering be expanded beyond construction for Class V 

experimental CO2 injection wells. 

5
The permitting of experimental wells includes making a determination about the 

protection of underground sources of drinking water ("USDW"). Changing wells 

from experimental to regular injection of CO2 should not change the 

determination. Owners/operators of experimental wells that wish to have them 

reclassified as Class VI injection wells should be allowed to do so with minimal 

addition submittals. However, if the Director determines that conversion of a 

well to Class VI would endanger USDW, grandfathering should not be permitted. 

Duke Energy recognizes that there are differences between Class II and Class V 

wells. Class II wells are associated with enhanced oil and gas recovery. The 

strata that contained the oil and gas for millions of years should be good 

candidates for GS of CO2. While long term GS of CO2 was not the goal during the 

permitting of Class I wells, the Director should nonetheless consider 

grandfathering them for reclassification to Class VI wells. Owners/operators of 

Class II wells used for long-term GS of CO2 would still need to demonstrate that 

doing so would not pose a danger to USDW. Before a Class II well is permitted as 

a Class VI well, however, the owner/operator should be required to meet all 

other permitting requirements for a Class IV well. 

The construction requirements for Class I wells is very similar to what EPA 

proposes for Class VI wells. Duke Energy feels that once the integrity and 

stability of the well have been demonstrated in a CO2 rich environment by the 

owner/operator the construction of a Class I well should be grandfathered. As 

with Class II wells, all other requirements for a Class VI well would have to be 

met before an injection permit would be issued. 

Duke Energy recommends that the Final Rule allow permitted Class V experimental 

CO2 injection wells to be re-classified as Class VI wells based on initial 

permitting information unless the Director determines that the project would 

endanger USDWs. Class II wells should be considered for reclassification once 

all requirements for a Class VI well are met. Class I well construction should 

be grandfather upon demonstration that the well construction has and will 

maintain mechanical integrity while being used for GS of CO2. All other 

requirements of the final rule would apply for reclassification to Class VI. 

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 disagrees that other requirements (e.g., MITs, siting, monitoring, operational, and AoR 

requirements) should also be grandfathered. Following re-permitting of the project as GS, many 

of the unique factors of GS sites (e.g., increased reservoir pressures associated with large 

6
volumes of stored CO2 and the corrosivity of CO2 in the presence of water) will result in an 

increased risk profile, warranting the specific requirements in the final GS rule. Therefore, 

following re-permitting as Class VI wells, these projects must be subject to the operational, MIT, 

monitoring, reporting, plugging, and post-injection site care and site closure requirements in the 

final GS rule. See the discussion of EPA's final regulatory approach in the preamble to the GS 

rule for additional detail on these requirements. 

Letter ID: 0209 Comment ID: 22684 Letter Lines: 149 to 176 

Comment Code: 3300 2.2.1 Delineating the AoR/Modeling CO2 movement 

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

Comment: REEVALUATION OF AREA OF REVIEW ("AoR") 

Current UIC regulations require the owner/operator of a proposed injection site 

to determine the AoR based on the area necessary to include the calculated cone 

of pressure influence. The amount of CO2 that will be injected at a GS site over 

the life of a project will be tens if not hundreds of millions of tons. This 

quantity of CO2 along with uncertain dispersion characteristics makes it next to 

impossible to determine the correct AoR utilizing a fixed radius or simple 

mathematical method. 

Acceptable methods for determining the AoR should include but not be limited to 

multiphase fluid flow models. It is anticipated that modeling will improve over 

time as experience with CO2 sequestration increases. Demonstration projects 

should not be constrained by allowing only the use of current models. Any model 

based on accepted science that has been validated should be acceptable. Models 

should be calibrated using actual site data once it becomes available. 

The AoR for a GS site for CO2 will be dynamic and in all probability irregular 

in shape. Based on the quantity of CO2 to be sequestered at a site, the AoR 

could be hundreds of square miles. A significant amount of time and money would 

be needed to complete an up-front evaluation of the life of a project AoR. A 

large portion of this effort could be wasted since the injection plumb may not 

travel as anticipated. As a result of this uncertainty, Duke Energy recommends a 

phased evaluation for the AoR. The AoR should be reviewed periodically (every 

ten years or as agreed upon by the Director). This would allow any necessary 

corrective actions to be focused where needed. This approach would allow 

projects to proceed more expeditiously, reduce start-up costs and because of the 

periodic review, provide greater protection to USDW. 

Individual Response: EPA clarifies that the AoR must be delineated as part of the permit 

application, as required at §§146.82(a)(2) and 146.82(c)(1). The Agency believes that AoR 

delineation using computational modeling that accounts for the multiphase flow of CO2 and 

native fluids (i.e., naturally occurring salty water), including density-driven flow (i.e., 

7
buoyancy), is necessary to ensure protection of USDWs from endangerment. The computational 

models used for this purpose are required to predict the fate of injected CO2 and changes in 

formation pressure. EPA believes that the requirements at 146.84(c)(1) to delineate the AoR 

using computational modeling are appropriate and encompass the significant processes that 

could affect the location of the CO2 plume and associated pressure front. 

EPA agrees that modeling technology is likely to improve over time, and EPA believes that 

future AoR reevaluations, as required at 146.84(e), should incorporate the best modeling 

available. Periodic reevaluations also ensure that a deliberative effort is made to verify, based on 

monitoring and operational data, that the CO2 plume is moving within the subsurface as 

predicted. However, EPA clarifies that the AoR delineation process will not be phased. Owners 

or operators must delineate the entire AoR of the project prior to receiving an operating permit. 

This evaluation must include the entire region surrounding the geologic sequestration project 

where USDWs may be endangered by the injection activity. 

EPA agrees that phased corrective action may provide many benefits to a project including, but 

not limited to, spreading the burden of cost, avoiding delays in project start-up, allowing for use 

of future, improved corrective action techniques and addressing unanticipated changes in the 

movement of the CO2 plume or pressure front. 

Letter ID: 0209 Comment ID: 22685 Letter Lines: 178 to 192 

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 Code: 2100 1.6 Target Geologic Formations for GS 

Comment: TRANSFERENCE BETWEEN CO2 SEQUESTRATION METHODS 

Duke Energy recognizes that there are differences between Class II and Class VI 

wells. Class II wells are associated with enhanced oil and gas recovery which 

can be an avenue for CO2 sequestration. Aside from deep saline formations, other 

potential sequestration areas include coal seams (Enhanced Coal Bed Methane -- 

ECBM), and shale layers. Since EPA’s proposed rule addresses CO2 volumes in 

millions of tons per year, Duke Energy recommends providing as much flexibility 

as possible when addressing potential CO2 sequestration areas so that the rules 

governing CO2 sequestration are fully transferable should more than one 

sequestration method be selected or should circumstances dictate a change from 

GS to the EOR market or vice versa. Duke Energy believes that allowing 

grandfathering of the proposed provisions to address this type of transfer 

should be allowed except when the Director determines that conversion of a well 

between Class II and Class VI would endanger USDW. 

Individual Response: EPA acknowledges that site-suitability for GS is dependent on a number 

of factors and that many formation types may be suitable for GS. The final GS rule does not 

preclude injection into any non-USDW formation type, including unmineable coal seams, 

8
provided owners or operators can demonstrate that GS can be performed in a manner that 

protects USDWs from endangerment. The Agency anticipates that in the near-term, most GS in 

unmineable coal seams will continue to be experimental. Such projects may be permitted as 

Class V experimental technology wells if they are of an experimental nature (i.e., to test GS 

technologies and collect data). EPA will continue to review data on early GS projects, including 

those in unmineable coal seams, to determine whether the appropriate amount and types of 

information and documentation are required and being collected. EPA 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. 

With respect to grandfathering, EPA recognizes that the oil and gas industry has decades of 

experience injecting CO2 for ER and that many Class V experimental technology wells are 

specifically designed for injection of CO2 and are being constructed to Class I non-hazardous 

waste well specifications. In the final rule, at §146.81(c), owners or operators seeking to 

grandfather existing Class I, II, or V wells for GS must demonstrate that the grandfathered wells 

were engineered and constructed to meet the requirements at §146.86(a) and ensure protection of 

USDWs from endangerment in lieu of requirements at §146.86(b) and §146.87(a). 

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. For more information, please see the discussion on 

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

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 

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

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 allows 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). 

9
Letter ID: 0209 Comment ID: 22686 Letter Lines: 194 to 206 

Comment Code: 1310 1.1.2.4 Comments on other "out of scope" issues, e.g., pore space 

ownership 

Comment: INJECTION ACTIVITIES THAT CROSS STATE BOUNDARIES 

In view of the likelihood that CO2 injection activities on GS projects will 

cross state boundaries, Duke Energy joins other stakeholders in urging EPA to 

reconsider its position of not addressing cross-state boundary issues in this 

rule-making. Instead, EPA should provide directives to states and corresponding 

certainty to owners and operators of GS projects when the AoR crosses state 

lines. At a minimum, the Final Rule should provide that the state in which the 

well head is located should be the primary state for purposes of permitting the 

Class VI well for GS of CO2. EPA should also direct the primary state to 

consult, coordinate and cooperate with each state within the AoR. The Final Rule 

should establish guidelines for the consultation, coordination and cooperation 

between the primary state and ach state within the AoR. 

Individual Response: EPA acknowledges that CO2 plumes may cross state or even international 

boundaries and encourages cooperation and coordination among permitting authorities. The final 

Class VI GS rule, at §146.82(a)(2), requires the owner or operator to identify all State, Tribal, 

and Territorial boundaries within the AoR. Based on this information, the Director must provide 

written notification to all States, Tribes, and Territories to inform them of the permit application 

and ensure that they are involved in any necessary processes; this new requirement was added to 

the final rule at §146.82(b). The Agency encourages transparency in the permitting process and 

anticipates that State-State/State-Tribal communication on Class VI permitting will facilitate 

information sharing and encourage safe, protective projects. 

EPA clarifies that the Class VI permit must be issued by the permitting authority in the state 

where the wellhead is located pursuant to UIC regulations. 

Letter ID: 0209 Comment ID: 22687 Letter Lines: 208 to 222 

Comment Code: 5240 2.8.2.2 Post injection timeframe (seeking comment) 

Comment: FINANCIAL RESPONSIBIILITY AND RISK MANAGEMENT APPROACH 

EPA is proposing a default time period of fifty years for post-injection 

activities. Although the proposed rules would gives the Director the discretion 

to adjust the default time period, such a provision will create tremendous 

uncertainty and impose unnecessary regulatory burden and cost on regulators. 

Protecting USDW and commercializing GS technology for CO2 would be better served 

by focusing on site characterization and a site-specific performance based 

approach to well closure that takes into consideration the particular needs of 

each CO2 sequestration site. In addition, a fifty-year default period could 

10
actually discourage owners or operators from undertaking proper site 

characterization and working to develop innovative ways to safety close wells in 

a shorter time period. It would also introduce significant financial uncertainty 

that could make actually obtaining necessary financial assurances Difficult if 

not impossible. 

Individual Response: EPA agrees with commenters that there will be circumstances where it 

can be demonstrated in less than 50 years that the plume and pressure front no longer pose a risk 

of endangerment to USDWs. 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 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. 

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. 

To the comment expressing concern about financial responsibility, EPA recognizes that there are 

challenges associated with assuring funding for activities that will occur far in the future. 

However, the Agency believes that in order to protect USDWs from endangerment under the 

SDWA operators must demonstrate under §146.85 that financial resources are available to plug 

the injection well and provide post-injection site care at the point in time that the first CO2 is 

injected. 

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose 

of the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects 

USDWs from endangerment. 

EPA agrees that proper site characterization is a critical component of ensuring that USDWs are 

protected. However, EPA disagrees that this is a substitute for post-injection site care. EPA 

believes that extensive post-injection monitoring is necessary to protect USDWs from 

endangerment. 

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Letter ID: 0209 Comment ID: 22688 Letter Lines: 224 to 245 

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

Comment: STATE PRIMACY 

The proposed rule seeks comment on whether states should be permitted to seek 

primacy for Class VI wells, noting the Agency’s belief that "the most effective 

approach for the comprehensive management of CO2 GS projects would be achieved 

at the State and Tribal level." Duke Energy believes it is appropriate to allow 

States to obtain primacy for only Class VI wells. States should play a key role 

in managing CO2 GS projects going forward, as they have with Class II wells for 

decades. The experience states have gained by regulating CO2 injection through 

the existing programs can offer many benefits in the context of Class VI wells. 

State regulators have familiarity with local environmental, geologic, and 

financial concerns, and in many cases have pre-existing relationships with the 

regulated community that can facilitate implementation of a new and complex 

regulatory program. Further, some states are moving ahead with developing their 

own legislation and regulations related to carbon capture and storage ("CCS") 

activities--in many cases developing laws and rules that include unique 

provisions and provide incentives for the development of new CCS projects. 

Allowing those states to take on primacy for Class VI wells (in particular, 

allowing them to take on primacy for Class VI wells without assuming the 

regulatory burden that may be associated with other well classes) will help 

ensure that they are given credit and recognition for their groundbreaking work 

in this area. 

Individual Response: EPA agrees 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. In the past, EPA has not accepted UIC primacy applications 

for individual well classes under Section 1422 of SDWA. In other words, if a State wanted 

primacy for Class I wells, the State would also need to accept responsibility for Class III, IV, and 

V wells. This policy has been in place since the initiation of the UIC Program in the early 1980s 

and was intended to encourage states to take full responsibility for UIC programs, avoid 

duplication of efforts, and provide for administrative efficiencies. 

However, 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 

12
comprehensive CCS management approach. 

The Agency believes that it is important for states to use their unique efficiencies to promote 

adoption of this burgeoning and important technology, while assuring that USDWs are protected 

from endangerment through the UIC regulatory framework. EPA believes that, due to the 

importance of implementing an effective, comprehensive, and seamless CCS program, States 

should be provided the flexibility to obtain primacy for Class VI only. 

EPA also believes that allowing states to apply only for Class VI primacy will shorten the 

primacy approval process for states. EPA's willingness to accept independent primacy 

applications for Class VI wells represents a shift in its longstanding policy of discouraging 

"partial primacy." 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 

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 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 recognizes that some states have already begun legislative efforts that are wider in scope 

than the Federal GS rule and believes that allowing Class VI primacy (independent of other well 

classes) may encourage states to take responsibility for implementation of a more comprehensive 

approach to managing CCS projects (e.g., capture, transportation, and geologic sequestration). 

Letter ID: 0209 Comment ID: 22689 Letter Lines: 247 to 253 

Comment Code: 1420 1.2.1.1 Support the GS rulemaking 

Comment: CONCLUSION 

Duke Energy appreciates the opportunity to provide comments on this important 

rulemaking. Having a workable regulatory program in place for the geologic 

sequestration of CO2 is absolutely essential to this country’s ability to reduce 

greenhouse gas emissions at a reasonable cost and without eliminating coal as a 

viable energy resource. 

Individual Response: EPA believes that the creation of a new injection well class (VI) under the 

existing UIC Program is necessary to enable the use of GS as a climate change mitigation 

technology in a manner that protects USDWs from endangerment. EPA agrees that the UIC 

Program, under the authority of the SDWA, provides a strong framework for regulating injection 

of CO2 for GS and adds that the GS regulation tailors the UIC requirements to address the 

13
14

unique issues associated with large-scale GS including large injection volumes, the relative 

buoyancy of CO2, its corrosivity in the presence of water, the potential presence of impurities in 

captured CO2, and its mobility within subsurface geologic formations.