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.
 

December 8, 2008 

Water Docket 

Environmental Protection Agency 

Mailcode: 2822T 

1300 Pennsylvania Avenue NW 

Washington, DC 20460 

Re: Docket ID No. EPA-HQ-OW-2008-0390 

Electronically Delivered: Via: www.regulations.gov 

To Whom It May Concern: 

Company Introduction and Frame of Reference for Comments

Global Energy, Inc. (Global) appreciates the opportunity to comment on the Proposed 

Rule: 40 CFR Parts 144 and 146 Federal Requirements Under the Underground 

Injection Control (UIC) Program For Carbon Dioxide (CO2) Geologic Sequestration (GS) 

Wells. 

Global is actively developing gasification based energy production projects, with 

particular focus on the production of Synthetic Natural Gas (SNG), Fischer-Tropsch 

(F-T) liquids, Hydrogen, as well as electric power generation via Integrated Gasification 

Combined Cycle (IGCC) technology. Oxygen blown, slagging gasification is the only 

version of gasification we consider to be true gasification. These are closed systems 

without primary stack or vent. Carbonaceous feedstock such as Petroleum Coke 

(petcoke), coal, as well as renewable and biomass materials can all readily be 

converted into synthetic gas and by further processing into these other products. We 

have a project partially under construction in Lima, Ohio that may well be the first of the 

next generation gasification facilities in this country. The above mentioned products all 

include carbon capture as inherent process steps for meeting product specification. In 

IGCC power generation, carbon capture may be “post-combustion”, but the superior 

path would be “pre-combustion”, which results in a hydrogen rich fuel and carbon 

capture, resulting in CO2 emission performance comparable or superior to that of 

natural gas. The critical consideration with these processes is management of the 

captured CO2!

Importantly, and most relevant to this proposed rule, our corporate vision and intention 

is to implement GS and Enhanced Oil Recovery (EOR) on all our projects. To this end 

we have identified both EOR and GS opportunities and geologic horizons within 

reasonable proximity to our Lima Energy IGCC Facility. While these will both require 

dedicated effort to implement, we are excited about the prospect. More specifically, 

with respect to this rule, the known geologic horizon immediately beneath the Lima 

facility, with extensive aerial extent, depth and thickness, has already been 

demonstrated to be well suited to GS. Moreover, the horizon has already been used for 

UIC purposes, with both geologic and seismic evaluation. 

Global Energy Inc, Suite 2300, 312 Walnut Street, Cincinnati, OH 45202, USA 

Tel: 513-621-0077 • Fax: 513-621-5947 
2 

Global Energy Inc, Suite 2300, 312 Walnut Street, Cincinnati, OH 45202, USA 

Tel: 513-621-0077 • Fax: 513-621-5947 

Introduction

Global appreciates the opportunity to comment on this proposed rule, for the protection 

of USDW by appropriate siting and installation of Class VI Wells for the Injection and 

GS of CO2. We strongly support the broad intent of the rule and believe it will ultimately 

foster accelerated implementation of carbon management programs. The US 

Department of Energy has identified numerous feasible locations across the country, 

some of which are very large and extensive, for geologic sequestration. Some of these 

are today being used with DOE’s Regional Testing Programs. 

1. The siting criteria, including defining of the appropriate “Area of Review”, seismic 

evaluation, extensive modeling and characterization are sufficiently rigorous that it is 

reasonable to anticipate minimal risks of leakage will exist long term. This minimal 

risk therefore argues in favor of a simple and pragmatic program. 

2. Well installation, operation, monitoring, record keeping, and corrective action are 

similarly rigorous and reasonably pragmatic; and they materially minimize the 

potential for inappropriate actions. 

Specific Comments

Delegation of Authority

1. Global supports EPA’s intent to delegate implementation of the program to 

authorized state agencies, and recommends ensuring that the state has ultimate 

decision authority over lower government entities such as counties and cities. The 

authority should also prescribe appropriate public involvement in siting decisions, 

and a process for review. They should however not allow extensive obstruction of 

technically decided decisions, or the program will have limited adoption and support. 

2. EPA should set standards and criteria that will result in “reasonably consistent” 

implementation and results regardless of geographic location. 

3. EPA should establish a hierarchy of authority for decision making and oversight, to 

ensure interstate and inter-jurisdictional conflicts are avoided. In this, Global 

appreciates that some states have moved ahead to implement carbon management 

programs. However, it is our view that effective and early implementation will be 

best served by consistency across the board. We therefore encourage EPA to 

review the programs of all states and select the common threads that are most 

suitable to early and effective implementation. 
3 

Global Energy Inc, Suite 2300, 312 Walnut Street, Cincinnati, OH 45202, USA 

Tel: 513-621-0077 • Fax: 513-621-5947 

Risk Management

1. Global concurs with the EPA view that the risk of asphyxiation and acute or chronic 

health effects is minimal. Pipeline leaks are rare and readily managed by existing 

authorities. Similarly wellhead and well leaks are uncommon and are readily 

managed with current technologies. EPA proposals for surface and down-hole 

shutoffs are reasonable additions to mechanical designs. 

2. Global also agrees that, adverse impacts to ecosystems from CO2 injection 

activities, is similarly minimal. Leaks will be small and flora do benefit from CO2 for 

growth. 

3. Global supports EPA’s view that the oil and gas industries have experience that can 

inform and facilitate pragmatic implementation of this rule. Activities to support 

siting, and well installation, are readily accomplished and are common to those 

industries. 

Implementation

1. Global strongly believes that excessive rigor in siting and well installation criteria, as 

well as post closure care and financial assurance for 50-years, would adversely 

impact acceptance of the program as well as the speed with which large 

(meaningful) scale carbon management develops. 

We appreciate the challenge in balancing security of sequestration. However 

advocating proven and reliable applications based on use of oil & gas based 

technology should be adequate to ensure long-term safety and reliability. 

Our view is that the likelihood of leakage from a GS well is relatively low, making 

50-years of post closure monitoring wholly unreasonable. 

2. Your note about the Weyburn EOR project in Saskatchewan Province, Canada is 

valid and highly relevant. Not only has the project demonstrated the commercial 

viability of EOR, but it has also rigorously demonstrated measurable, quantified and 

verified carbon storage. That is, the CO2 is remaining in horizon and is conforming 

to and validating model predictions. 

3. We highly recommend that EPA think in terms of the “80-20 rule” of pragmatism 

when determining how to implement the conversion of an EOR well to a 

sequestration well. It is arguable that an EOR well is sufficiently relevant to a 

Class-6 well and has sufficient integrity to give it credit (at least partial credit) in the 

carbon injection and storage calculus. Reasonable mechanical retrofits may be 

appropriate, without having to replace casing, for example. 

In this we strongly support the EPA suggestion that EOR wells might be 

“grandfathered” when considering conversion to a GS well. Reasonable rework, 

though not reinstallation (or re-cementing, for example) might be decided on a 

case-by-case basis. That is, a single well, or a few wells, are not likely to materially 

affect USDW. 
4 

Global Energy Inc, Suite 2300, 312 Walnut Street, Cincinnati, OH 45202, USA 

Tel: 513-621-0077 • Fax: 513-621-5947 

4. We strongly support that EPA should establish national standard and guidelines, and 

delegate implementation to states. Site selection and well installation criteria should 

be clear but flexible, affording states discretion and judgment with respect to risk 

management. 

CO2 as Hazardous Waste (RCRA or CERCLA)

1. We support the EPA view that injectate should be characterized relative to 40 CFR 

Part 261. We further believe that the stream can be treated to remove undesired 

contaminants – to the levels that thresholds are not triggered. 

2. Characterization and certification in the permit application should be a sufficient 

basis for assurance here. Periodic sampling and analysis on some reasonable 

frequency during injection is acceptable. On the other hand, we do not believe that 

this measurement and reporting needs to be more than perhaps quarterly, as the 

adverse impact of exceedances for relatively short periods is not likely to be 

geologically significant very fast. Corrective action to mitigate the effects of an 

incorrect injection fluid (but not to remedy an injection already accomplished) needs 

to be pragmatic and not onerous. 

3. As with Class I well liability exemptions, Class VI wells, once their injectate is 

characterized and approved (as not triggering CERCLA or RCRA), and regular 

sampling of the stream for quality control is implemented Æ then a similar exemption 

is warranted. 

Alternative Selection

1. EPA proposes four alternatives for GS regulations and asks for comments on them. 

Our fundamental belief is that the program should be as simple and pragmatic as 

possible, and in recognition of the initial rigor involved, once the well is sited, and 

installed, the risk of a leak is extremely minimal. 

2. As such, we support EPA’s selection of Alternative 2, as a balance between the rigor 

and the security, delegating much of implementation to the states, who have local 

knowledge. 

BUT, once that is done, the closure, post-closure and long-term care and monitoring 

(50-years of financial responsibility) with attendant financial responsibility, needs to 

be significantly relaxed and made much more reasonable. 

Modeling

1. We support computational fluid flow modeling during injection well site selection, as 

well as conformational modeling to confirm performance from time to time. This is 

related to the periodic re-evaluation of the Area of Review. It seems that the 

geology and capacity of the horizon can dictate the frequency – but perhaps five 

years will prove reasonable in many cases. 
5 

Global Energy Inc, Suite 2300, 312 Walnut Street, Cincinnati, OH 45202, USA 

Tel: 513-621-0077 • Fax: 513-621-5947 

2. There is an increasing body of knowledge that computational fluid flow modeling is 

feasible and can inform an injection operation about performance, and point toward 

changes that may be appropriate. We are familiar with those involved with the 

Weyburn Field in Canada, mentioned by EPA. 

Well Installation

1. We support the basic and conservative installation criteria proposed. We question 

whether casing to the injection horizon, cementing the full length is really necessary. 

It seems certain that experts in geology and well installation should have the latitude 

to determine the appropriate installation method. Appropriate instrumentation and 

shut-offs are reasonable. 

2. Horizontal well technology is well known and within the expertise of drilling 

companies today. We strongly support the use of horizontal wells for this 

application. As noted in the discussion, EPA acknowledges that horizontal wells will 

provide excellent benefits, particularly with respect to injection volume and capacity 

of the geology to handle the rate of injection; as well as minimizing the number of 

surface sites to achieve the desired injection volume and rate. 

3. We recommend that specifics of the site, as well as fluid and geologic 

characteristics, dictate the materials used in well construction, particularly whether 

stainless steel is really appropriate. We suspect Grade 316 stainless may not 

always be appropriate or necessary especially when considering conversion of EOR 

wells to GS duty. 

4. Certainly acid resistant cement represents a modest cost for the benefit of long term 

well integrity. 

Well Operation

1. We do not believe that hydraulic fracturing should be restricted or prohibited where it 

can be demonstrated that existing faults are sufficiently remote from the injection site 

or the geology is otherwise appropriate for it. 

2. Similarly, we also believe that the geology itself can inform the siting process and 

application as to whether fracturing will be appropriate, even without existing faults in 

proximity to the well location. 

3. Injection pressure limitations, controlled by instrumentation, and monitored and 

recorded, are appropriate. We support the reasonableness of the suggested 90 

percent criteria as a pressure limitation. We also counsel reasonableness with 

respect to selecting what that pressure is. 

4. We believe discretion afforded the states for implementation of this program is 

warranted. 
6 

Global Energy Inc, Suite 2300, 312 Walnut Street, Cincinnati, OH 45202, USA 

Tel: 513-621-0077 • Fax: 513-621-5947 

5. Automatic shutoff down hole, in addition to surface shut off, is appropriate. 

6. We support “mechanical integrity testing” and monitoring, in some respects (on a 

continuous basis). Sensors and data logging is readily available. Semi-annual 

reporting, along with other reporting requirements, is also quite reasonable. 

Proximity to USDW

1. State discretion to decide whether injection below the lower most USDW is 

necessary. It is reasonable that certain combinations of geologic strata can readily 

protect a USDW from above not just from below. 

Again, we appreciate the opportunity to provide these comments and look forward to 

well-founded regulations that provide a pragmatic, cost effective and expeditious path 

forward in the management of carbon dioxide via the utilization of Class VI wells. 

Respectfully Submitted, 

___________________________ 

Dwight N. Lockwood, PE, QEP 

Group Vice President 

P: 513.621.0077 

Email: dnlockwood@globalenergyinc.com 
Letter ID: 0141 

Commenter: Dwight Lockwood, PE, QEP 

Organization: Global Energy, Inc. 

Letter ID: 0141 Comment ID: 23089 Letter Lines: 69 to 74 

Comment Code: 1420 1.2.1.1 Support the GS rulemaking 

Comment: the Injection and GS of CO2. We strongly support the broad intent of the rule 

and believe it will ultimately foster accelerated implementation of carbon 

management programs. The US Department of Energy has identified numerous 

feasible locations across the country, some of which are very large and 

extensive, for geologic sequestration. Some of these are today being used with 

DOE’s Regional Testing Programs. 

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. For additional 

information on site characterization, please also see the discussion of EPA’s Final Regulatory 

Approach in the preamble to the final GS rule. 

Letter ID: 0141 Comment ID: 23090 Letter Lines: 76 to 80 

Comment Code: 3100 2.1 Proposed Geologic Siting Requirements (40 CFR 146.83) 

Comment: 1. The siting criteria, including defining of the appropriate Area of Review, 

seismic evaluation, extensive modeling and characterization are sufficiently 

rigorous that it is reasonable to anticipate minimal risks of leakage will exist 

long term. This minimal risk therefore argues in favor of a simple and 

pragmatic program. 

Individual Response: EPA acknowledges the comment and believes that a detailed geological 

site characterization (required under §146.82) is essential to evaluating the presence and 

adequacy of the various geologic features necessary to receive and confine injected CO2 for GS. 

The requirements for geologic site characterization are based on a long standing UIC regulatory 

framework developed to address specific risks to USDWs posed by injection. The Class VI GS 

requirements are tailored so that they are appropriate for the unique nature of injecting large 

volumes of CO2 into a variety of geological formations for long-term storage. 

1
Letter ID: 0141 Comment ID: 23091 Letter Lines: 82 to 84 

Comment Code: 1420 1.2.1.1 Support the GS rulemaking 

Comment Code: 3820 2.3.1 Well construction procedures 

Comment: 2.Well installation, operation, monitoring, record keeping, and corrective 

action are similarly rigorous and reasonably pragmatic; and they materially 

minimize the potential for inappropriate actions. 

Individual Response: EPA acknowledges the comment and agrees that protection of USDWs 

from endangerment and prevention of fluid movement between formations is paramount. 

Appropriately designed and constructed wells are necessary to prevent endangerment to USDWs 

and maintain integrity of the well throughout the lifetime of a GS project. This is the foundation 

of the requirements for construction and pre-operational testing of Class VI wells at §§146.86 

and 146.87. 

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: 0141 Comment ID: 23092 Letter Lines: 90 to 92 

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

Comment: 1.Global supports EPA’s intent to delegate implementation of the program to 

authorized state agencies, and recommends ensuring that the state has ultimate 

decision authority over lower government entities such as counties and cities. 

Individual Response: EPA agrees with commenters on the importance of states having primacy 

for GS wells given the variety of geologic settings in which GS will be applied. EPA recognizes 

that State, Tribal, Territorial, and DI UIC Program Directors are in the best position to evaluate 

the unique issues related to well depth, geology, and hydrogeology that are posed by a Class VI 

well. Some degree of flexibility is needed for Class VI wells because each decision made will be 

site-specific and conditions will differ from state to state. The GS rule balances the need for 

these site-specific decisions with the need for minimum standards to ensure national consistency. 

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 encourages states to accept 

primacy for Class VI, and believes that, due to the importance of implementing an effective, 

comprehensive, and seamless CCS program, States should be provided the flexibility to obtain 

2
primacy for Class VI only. 

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 

comprehensive CCS management approach. 

Regarding authority provided to local governments, EPA clarifies that its authority to delegate 

primary enforcement responsibility extends only to states (including tribes and territories), not 

local governments. EPA notes that local governments have the right to provide input on a 

proposed Class VI permit during the public notice and comment period (consistent with Part 

124) required to be included in every State approved program under §145.11. Additionally, the 

state is required to have a program which ensures consideration of all comments before a final 

permit decision is made. 

Letter ID: 0141 Comment ID: 23093 Letter Lines: 93 to 96 

Comment Code: 5500 2.1 Comments on Involving the Public in Permitting Decisions 

Comment: The authority should also prescribe appropriate public involvement in siting 

decisions, and a process for review. They should however not allow extensive 

obstruction of technically decided decisions, or the program will have limited 

adoption and support. 

Individual Response: The Agency believes that public participation is an important part of the 

UIC permitting process and wants to ensure wide access to decision-making processes and 

information on projects that may affect the public. 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 request a public hearing on the draft permit. EPA encourages operators and 

permitting agencies to begin communicating with the public by providing information as early in 

the process as possible. Encouraging public participation allows the permitting authority to 

understand public viewpoints, preferences, and concerns about the project, which might help 

avoid public misperceptions about the nature and safety of GS projects and forestall resistance 

later in the permitting effort. 

3
Letter ID: 0141 Comment ID: 23094 Letter Lines: 98 to 107 

Comment Code: 1260 1.1.1.5 More certainty/stringency is needed 

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

Comment: 2.EPA should set standards and criteria that will result in reasonably 

consistent implementation and results regardless of geographic location. 

3.EPA should establish a hierarchy of authority for decision making and 

oversight, to ensure interstate and inter- jurisdictional conflicts are avoided. 

In this, Global appreciates that some states have moved ahead to implement 

carbon management programs. However, it is our view that effective and early 

implementation will be best served by consistency across the board. We 

therefore encourage EPA to review the programs of all states and select the 

common threads that are most suitable to early and effective implementation. 

Individual Response: EPA agrees that it is important to balance flexibility and national 

consistency. The GS rule sets forth minimum Federal requirements, tailored to the unique nature 

of CO2 GS, which must be met in order to ensure USDW protection from endangerment. EPA 

acknowledges the importance of flexibility for certain Class VI well requirements given the 

variety of geologic settings in which GS will be applied and therefore affords the Director 

discretion when making permitting decisions. Such requirements where the Director has 

discretion include whether to require owners or operators to identify and characterize additional 

confining zones, as specified in §146.83, whether to require surface air monitoring and/or soil 

gas monitoring, as specified in §146.90, and whether to extend or shorten the post-injection site 

care period or approve an alternative post-injection site care timeframe as part of the permitting 

process, as specified in §146.93. The GS rule balances the need for site-specific decisions with 

the need for minimum standards to ensure national consistency and USDW protection from 

endangerment while also ensuring that states have the data they need to make permitting 

decisions. EPA Headquarters also plans to review initial permits to ensure that the final rule, 

including all permitting decisions, are implemented consistently, and to ensure that USDW 

protection goals are consistently met across differing geologic situations. 

EPA understands that the CO2 plumes for large GS projects may cross State, Tribal, Territorial, 

or EPA Regional boundaries. The final 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, as specified in §146.82(b), and ensure that they are 

involved in any necessary processes (e.g., development of the emergency and remedial response 

plan, as specified in §146.94). The Agency encourages transparency in the permitting process 

and anticipates that State-State/State-Tribal communication on GS permitting will facilitate 

information sharing and encourage safe, protective projects. 

Because some GS projects will require coordination across State, Tribal, and Territorial 

jurisdictions, the Agency will work with the appropriate entities to facilitate communication 

among States, Tribes, and Territories during the implementation phase of the GS regulation. 

4
Such communication may involve other organizations such as the Sierra Club, NDWAC, 

associations, and other experts. However, the responsibility for addressing such subjects 

ultimately rests with the States, Tribes, and Territories with primacy. EPA is developing primacy 

implementation materials for states that describe recommended approaches to addressing transboundary issues during the permitting of Class VI wells under the GS regulation. The materials 

will be available at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

In response to questions about which state or region would oversee the permit for projects where 

the AoR spans State, Tribal, or Territorial boundaries, EPA clarifies that issuance and oversight 

of a GS permit, including any associated AoR boundary-related coordination, is the 

responsibility of the primacy (State, Tribe, or Territory) or regional DI program in the state 

where the injection well is located. 

Letter ID: 0141 Comment ID: 23095 Letter Lines: 111 to 114 

Comment Code: 1650 1.3.5 Human health impacts 

Comment: 1.Global concurs with the EPA view that the risk of asphyxiation and acute or 

chronic health effects is minimal. Pipeline leaks are rare and readily managed 

by existing authorities. Similarly wellhead and well leaks are uncommon and are 

readily managed with current technologies. EPA proposals for surface and downIndividual Response: EPA recognizes that injecting large volumes of CO2 for GS poses unique 

challenges that, if not properly managed, could endanger drinking water sources and have other 

adverse impacts. However, with proper site selection, the final, tailored, Class VI requirements 

address the large volumes of CO2 injected, its buoyancy, potential corrosivity in the presence of 

water, and potential impurities in the CO2 stream. In addition, EPA expects the tailored 

permitting, siting, construction, operation, monitoring, and post-injection site care requirements 

in the GS rule to prevent leakage from injection formations and protect USDWs. EPA adds that 

pipeline leaks and risk of asphyxiation are outside the scope of the GS rulemaking. 

Letter ID: 0141 Comment ID: 23096 Letter Lines: 114 to 115 

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

Comment: readily managed with current technologies. EPA proposals for surface and downhole shutoffs are reasonable additions to mechanical designs. 

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 

5
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: 0141 Comment ID: 23097 Letter Lines: 117 to 119 

Comment Code: 1660 1.3.6 Ecosystem impacts (soil, air, surface water) 

Comment: 2.Global also agrees that, adverse impacts to ecosystems from CO2 injection 

activities, is similarly minimal. Leaks will be small and flora do benefit from 

CO2 for growth. 

Individual Response: EPA acknowledges that there are potential risks associated with GS. The 

purpose of the Class VI requirements is to minimize and mitigate potential/identified risks 

through proper site characterization, well construction, operation, monitoring, post-injection site 

care, and site closure and to ensure protection of USDWs. EPA believes that the measures in the 

GS rule that directly mitigate the possibility of CO2 leakage out of the injection zone will also 

indirectly mitigate the risks to receptors mentioned by the commenters, including fresh water, 

wildlife, ecosystems, and agriculture. 

Letter ID: 0141 Comment ID: 23098 Letter Lines: 121 to 124 

Comment Code: 1940 1.4.4.3 Consultations with Industry; experience with other wells 

Comment: 3.Global supports EPA’s view that the oil and gas industries have experience 

that can inform and facilitate pragmatic implementation of this rule. 

Activities to support siting, and well installation, are readily accomplished 

and are common to those industries. 

Individual Response: EPA recognizes that the oil and gas industry has decades of experience 

injecting CO2 for the purpose of ER, and that sites used for ER may be suitable for GS and may 

be among the first GS sites. EPA also recognizes that a by-product of ER activities is that a 

certain percentage of the CO2 is trapped in the receiving formation. 

Also, since field experience and well construction, injection, and monitoring information 

relevant to GS comes from operations that inject acid gas or inject CO2 for ER, the Agency has 

conducted evaluations regarding these commercial field operations and continues to track GSrelevant developments in these commercial operations. Some of the research that informs the 

final GS rule was conducted at ER sites. 

6
Letter ID: 0141 Comment ID: 23099 Letter Lines: 128 to 135 

Comment Code: 3820 2.3.1 Well construction procedures 

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

Comment: 1.Global strongly believes that excessive rigor in siting and well installation 

criteria, as well as post closure care and financial assurance for 50-years, 

would adversely impact acceptance of the program as well as the speed with which 

large (meaningful) scale carbon management develops. 

We appreciate the challenge in balancing security of sequestration. However 

advocating proven and reliable applications based on use of oil & gas based 

technology should be adequate to ensure long-term safety and reliability. 

Individual Response: EPA disagrees that a post-injection site care timeframe of 50 years is 

excessive or that it overstates the risk of GS. 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 

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 there may be sites where the 50 year post injection site care 

timeframe may be either not appropriate or more burdensome than necessary based on sitespecific conditions. 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 

7
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. 

To the comment about the cost of post-injection site care, EPA does not agree that post-injection 

site care timeframes longer than 30 years will be prohibitively expensive. In fact, EPA believes 

that post-injection site care monitoring will represent a relatively minor component of total 

project cost, and will provide an essential level of protection from endangerment for USDWs. A 

discussion of the costs attributed to monitoring technologies (used during injection and the postinjection site care timeframes) is available in the Technology and Cost Document for the GS 

rule, which is in the federal docket for this rulemaking. EPA believes that it is logical to make 

use of existing monitoring infrastructure at a GS site in order to ensure USDWs are not 

endangered. 

EPA also recognizes the concerns associated with ensuring financial responsibility for the long 

time frames over which post-injection site care will be conducted. EPA is developing guidance 

on financial responsibility to assist owners or operators in evaluating the requirements of 

§146.85 and to assist Directors in evaluating financial responsibility demonstrations. The 

guidance describes the types of financial mechanisms that operators may choose to use when 

evaluating the financial responsibility requirements for GS wells and it will also include a section 

on how to estimate costs to support accurate financial responsibility demonstrations. The 

guidance will be available at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

EPA recognizes that the oil and gas industry has decades of experience injecting CO2 for the 

purpose of enhanced recovery and that many of the wells used for ER may be suitable for GS. 

However, EPA believes that GS is sufficiently different from Class II ER operations to warrant 

the tailored construction requirements for Class VI wells at §146.86. For example, the volume of 

CO2 anticipated to be injected in Class VI wells is significantly greater than for Class II wells. 

Reservoir pressure conditions will 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. Therefore, Class VI GS reservoir pressures will increase more in 

comparison to Class II ER during the injection phase of the GS project. 

Letter ID: 0141 Comment ID: 23100 Letter Lines: 137 to 138 

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

Comment: Our view is that the likelihood of leakage from a GS well is relatively low, 

making 50-years of post closure monitoring wholly unreasonable. 

Individual Response: EPA disagrees that a post-injection site care timeframe of 50 years is 

excessive or unreasonable. EPA proposed a default post-injection site care timeframe of 50 years 

8
based on a review of research studies, industry reports, and existing environmental programs. 

This analysis was included in an EPA-prepared background document 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 there may be sites where the 50 year post injection site care 

timeframe may be either not appropriate or more burdensome than necessary based on sitespecific conditions. 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, as the commenter suggests. 

Letter ID: 0141 Comment ID: 23101 Letter Lines: 140 to 144 

Comment Code: 1858 1.4.2.4 International GS efforts 

Comment: 2.Your note about the Weyburn EOR project in Saskatchewan Province, Canada is 

valid and highly relevant. Not only has the project demonstrated the commercial 

viability of EOR, but it has also rigorously demonstrated measurable, quantified 

and verified carbon storage. That is, the CO2 is remaining in horizon and is 

conforming to and validating model predictions. 

Individual Response: EPA acknowledges the comment about Weyburn, and agrees that 

activities there have relevance for the rule. EPA has monitored progress at the site to gain input 

and information regarding GS, and will continue to do so. 

EPA is using an adaptive approach to regulating GS. EPA plans to collect and review project 

9
data every six years on early GS projects to determine whether the appropriate amount and types 

of information and appropriate documentation are required and being collected. The Agency will 

evaluate the information and determine if modifications to the requirements are necessary. 

Letter ID: 0141 Comment ID: 23102 Letter Lines: 146 to 158 

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: 2064 1.5.3.2 Grandfathering construction of Class II wells (seeking comment) 

Comment: 3.We highly recommend that EPA think in terms of the 80-20 rule of pragmatism 

when determining how to implement the conversion of an EOR well to a 

sequestration well. It is arguable that an EOR well is sufficiently relevant 

to a Class-6 well and has sufficient integrity to give it credit (at least 

partial credit) in the carbon injection and storage calculus. Reasonable 

mechanical retrofits may be appropriate, without having to replace casing, for 

example. 

In this we strongly support the EPA suggestion that EOR wells might be 

grandfathered when considering conversion to a GS well. Reasonable rework, 

though not reinstallation (or re- cementing, for example) might be decided on a 

case-by-case basis. That is, a single well, or a few wells, are not likely to 

materially affect USDW. 

Individual Response: EPA agrees that many Class II 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). 

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 adds that, 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. 

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

will assist Directors in evaluating 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 

10
long-term storage of large volumes of CO2. The guidance describes recommended methods the 

Director may use 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. 

Letter ID: 0141 Comment ID: 23103 Letter Lines: 160 to 163 

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

Comment: 4.We strongly support that EPA should establish national standard and 

guidelines, and delegate implementation to states. Site selection and well 

installation criteria should be clear but flexible, affording states discretion 

and judgment with respect to risk management. 

Individual Response: As described above, EPA will allow states to apply for primacy for Class 

VI wells independently of primacy for other well classes. The Agency will allow independent 

primacy for Class VI wells under §145.1(i) of the final GS rule. 

EPA is developing guidance materials and plans to conduct on-line and in-person training for 

States, Tribes, and Territories that describe the technical and administrative issues on developing 

and implementing GS regulations that are the equivalent of minimum Federal criteria and 

requirements. EPA is also developing materials for owners or operators on site characterization 

and well construction. The guidances will be available at 

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

EPA expects that both Headquarters and the Regions will work closely with the states during the 

early permitting process to ensure that flexibility is applied in a manner that ensures a consistent 

level of USDW protection from endangerment. EPA designed flexibility into the regulations to 

ensure that site-specific factors can be accounted for and expects that permit writers will use 

discretion where site-specific factors are important. As part of its adaptive approach, EPA also 

plans to review initial permits (after they are granted) to ensure that USDW protection goals 

have been consistently met across differing geologic situations. If necessary, EPA will reevaluate 

the flexibility granted to states in the rule. 

Letter ID: 0141 Comment ID: 23104 Letter Lines: 165 to 183 

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

Comment Code: 1640 1.3.4 CERCLA issues (seeking comment) 

Comment Code: 4620 2.6.2 Injectate monitoring 

Comment: CO2 as Hazardous Waste (RCRA or CERCLA) 

1.We support the EPA view that injectate should be characterized relative to 40 

11
CFR Part 261. We further believe that the stream can be treated to remove 

undesired contaminants to the levels that thresholds are not triggered. 

2.Characterization and certification in the permit application should be a 

sufficient basis for assurance here. Periodic sampling and analysis on some 

reasonable frequency during injection is acceptable. On the other hand, we do 

not believe that this measurement and reporting needs to be more than perhaps 

quarterly, as the adverse impact of exceedances for relatively short periods is 

not likely to be geologically significant very fast. Corrective action to 

mitigate the effects of an incorrect injection fluid (but not to remedy an 

injection already accomplished) needs to be pragmatic and not onerous. 

3.As with Class I well liability exemptions, Class VI wells, once their 

injectate is characterized and approved (as not triggering CERCLA or RCRA), and 

regular sampling of the stream for quality control is implemented then a 

similar exemption is warranted. 

Individual Response: EPA agrees that monitoring of the injectate prior to and during injection 

is important to allow for comparison of baseline data and operational-phase monitoring results to 

provide warning of potential USDW endangerment. For this reason owners or operators must 

perform an analysis of the chemical and physical characteristics of the CO2 stream, as required 

at §146.82 (a)(7)(iv). In addition, Section §146.90(a) requires owners or operators to perform 

analysis of the CO2 stream during injection operations with sufficient frequency to yield data 

representative of its chemical and physical characteristics. 

The necessary frequency of injectate analysis will be project-specific and will depend upon the 

CO2 source and the likelihood of variability in injectate composition. For example, a CO2-

capture process from a coal-fired power plant with a consistent coal source and operating 

parameters is likely to produce a CO2 stream with a fairly consistent composition. A process 

with a changing composition of coal may have more variability in the purity of the CO2 that is 

captured. In such a setting, more frequent sampling may be appropriate. The details of the 

sampling should be described in the testing and monitoring plan, which will be approved by the 

Director based on a review of site-specific information, including information on the source and 

characteristics of the injectate. 

EPA clarifies that, following an initial characterization of the injectate, EPA expects that the 

permit would stipulate the acceptable composition of the injectate (e.g., as CO2 plus an 

acceptable range of expected impurities). Any divergence from this would be a permit violation. 

EPA notes however, 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. 

Accordingly, the CO2 stream characterization requirements under the GS rule would not 

substitute for the obligation of a generator of RCRA solid waste to characterize its waste in 

accordance with EPA’s RCRA regulations. Injection of a RCRA hazardous waste may only 

occur in a Class I hazardous waste injection well. 

12
EPA notes that CO2 itself is not listed as a hazardous substance under CERCLA, although 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” (FPR) 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. 

The commenter’s reference to a Class I liability exemption is unclear and not legally correct. 

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. 

Letter ID: 0141 Comment ID: 23105 Letter Lines: 185 to 194 

Comment Code: 2330 1.7.3 Comments on Alternative 2 

Comment: Alternative Selection 

1.EPA proposes four alternatives for GS regulations and asks for comments on 

them. Our fundamental belief is that the program should be as simple and 

pragmatic as possible, and in recognition of the initial rigor involved, once 

the well is sited, and installed, the risk of a leak is extremely minimal. 

2.As such, we support EPA’s selection of Alternative 2, as a balance between the 

rigor and the security, delegating much of implementation to the states, who 

have local knowledge. 

Individual Response: EPA clarifies that it proposed Alternative 3 and subsequently has chosen 

Alternative 3 in the final rule. The technical requirements in Alternative 3 provide a balance 

between rigor and security and build upon the long-standing UIC regulatory framework for deep 

wells and are appropriately tailored to address the unique nature of full-scale CO2 GS, including 

the volumes of CO2 to be injected, the buoyant and mobile nature of the injectate, and its 

corrosivity in the presence of water to ensure the protection of USDWs. 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 low viscosity and therefore cannot ensure 

protection of USDWs. 

13
EPA believes that the GS rule (Alternative 3) offers the flexibility and discretion desired by 

commenters preferring Alternative 2 while protecting USDWs from endangerment. 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: 0141 Comment ID: 23106 Letter Lines: 196 to 198 

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

Comment: BUT, once that is done, the closure, post-closure and long-term care and 

monitoring (50-years of financial responsibility) with attendant financial 

responsibility, needs to be significantly relaxed and made much more reasonable. 

Individual Response: EPA disagrees that a post-injection site care timeframe of 50 years is 

excessive for most Class VI wells. 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 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 there may be sites where the 50 year post injection site care 

timeframe may be either not appropriate or more burdensome than necessary based on sitespecific conditions. 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 

14
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, as the commenter suggests. 

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

challenges associated with ensuring 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 owners or 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. 

Letter ID: 0141 Comment ID: 23107 Letter Lines: 200 to 204 

Comment Code: 3310 2.2.1.1 Comments in favor of requiring computational models to 

delineate the AoR (seeking comment) 

Comment: Modeling 

1.We support computational fluid flow modeling during injection well site 

selection, as well as conformational modeling to confirm performance from time 

to time. This is related to the periodic re-evaluation of the Area of Review. 

Individual Response: EPA acknowledges the commenter’s support of the modeling approach, 

and agrees that reevaluation of the AoR as required at 146.84(e) must incorporate monitoring 

and operational data gathered since the last model run. This will serve to verify that the CO2 

plume and pressure front are moving through the subsurface as predicted, that the delineation 

model is accurate (or identify needed changes), and refine testing and monitoring activities to 

ensure that USDWs are protected from endangerment and that there would be adequate warning 

of potential problems at the site before any endangerment could occur. 

Letter ID: 0141 Comment ID: 23108 Letter Lines: 205 to 206 

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

Comment: It seems that the geology and capacity of the horizon can dictate the frequency 

but perhaps five years will prove reasonable in many cases. 

Individual Response: EPA agrees that site-specific factors should be considered in the 

reevaluation schedule, and notes that the AoR and corrective action plan must specify the sitespecific monitoring and operational conditions that warrant reevaluation, as specified in 

§146.84(b)(2)(ii). In addition, 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 

15
reevaluation schedule is not sufficiently protective of USDWs. However, EPA believes that 

setting a minimum reevaluation frequency is appropriate. In the final rule, the Agency changed 

the minimum frequency for the AoR reevaluation at §146.84(e) from 10 years to 5 years in the 

final GS rule. EPA believes that this revised frequency addresses commenters' concerns about 

the inherent uncertainties in modeling CO2 movement, the emerging nature of GS technology, 

risk-based targeting of monitoring activities, and the unique nature of CO2 GS. In addition, 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: 0141 Comment ID: 23109 Letter Lines: 208 to 211 

Comment Code: 3310 2.2.1.1 Comments in favor of requiring computational models to 

delineate the AoR (seeking comment) 

Comment: 2.There is an increasing body of knowledge that computational fluid flow 

modeling is feasible and can inform an injection operation about performance, 

and point toward changes that may be appropriate. We are familiar with those 

involved with the Weyburn Field in Canada, mentioned by EPA. 

Individual Response: EPA also agrees that numerical computation, as required at 146.84(c)(1), 

may be necessary to calculate the complex AoR for a GS project. EPA believes that predicting 

the complex multiphase buoyant flow of the CO2, co-injectates, and compounds that may be 

mobilized due to injection requires the sophistication of computational models and in some cases 

may specifically require certain numerical models. EPA also agrees that physical measurement, 

(i.e. monitoring) is an important component to protecting USDWs from endangerment and will 

serve to calibrate computational model predictions during the AoR reevaluation to ensure that 

the AoR adequately represents the extent of the CO2 plume and pressure front. 

Letter ID: 0141 Comment ID: 23110 Letter Lines: 213 to 215 

Comment Code: 3820 2.3.1 Well construction procedures 

Comment: Well Installation 

1.We support the basic and conservative installation criteria proposed. We 

Individual Response: EPA acknowledges the comment and believes that appropriately designed 

and constructed wells are necessary to prevent endangerment to USDWs and maintain integrity 

of the well throughout the lifetime of a GS project. This is the foundation of the requirements for 

construction and pre-operational testing of Class VI wells at §§146.86 and 146.87. 

Letter ID: 0141 Comment ID: 23111 Letter Lines: 215 to 219 

16
Comment Code: 3822 2.3.1.1 Depth of surface casing (seeking comment) 

Comment Code: 3824 2.3.1.2 Cementing of long-string casing (seeking comment) 

Comment: 1.We support the basic and conservative installation criteria proposed. We 

question whether casing to the injection horizon, cementing the full length is 

really necessary. It seems certain that experts in geology and well 

installation should have the latitude to determine the appropriate installation 

method. Appropriate instrumentation and shut-offs are reasonable. 

Individual Response: EPA believes that the requirements for surface and long-string casing are 

necessary and also that they offer appropriate flexibility. The final GS rule requires, at 

§146.86(b)(2), that the surface casing must extend through the base of the lowermost USDW and 

be cemented to the surface, and that at least one long string casing must be cemented to the 

surface in one or more stages at §146.86(b)(3). It does not, however, specify how cementing 

would be accomplished, and gives flexibility to the owner or operator to propose alternate 

methods to provide a sufficient amount of cement to meet the standard that USDWs are 

protected from endangerment, subject to the approval of the Director. 

EPA notes that there are many potential ways to meet the requirement, such as the use of staged 

cementing. 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. 

EPA adds that other aspects of the rule allow flexibility based on site-specific considerations: 

with their permit applications, owners or operators must submit proposed well construction 

procedures, as specified at §146.82(a)(12), that address the specific drilling and injection 

environment and the chemical and physical nature of the CO2 injected stream. The Director must 

evaluate the appropriateness of the proposed construction based on site-specific information 

about the injection project, including injection pressures, injection and confining zone lithology, 

and information about the carbon dioxide stream, as provided in the final GS rule at 

§146.86(b)(1). 

Letter ID: 0141 Comment ID: 23112 Letter Lines: 219 to 219 

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

Comment: method. Appropriate instrumentation and shut-offs are reasonable. 

Individual Response: As described above, 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 

17
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 requiring the installation of automatic surface shut-off devices for onshore 

wells (and affording Director's discretion to require down-hole devices where necessary) ensures 

that proper precautions are taken to prevent subsurface fluid movement and ensure protection of 

USDWs, human health, and the environment. 

Letter ID: 0141 Comment ID: 23113 Letter Lines: 221 to 227 

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

Comment: 2.Horizontal well technology is well known and within the expertise of drilling 

companies today. We strongly support the use of horizontal wells for this 

application. As noted in the discussion, EPA acknowledges that horizontal wells 

will provide excellent benefits, particularly with respect to injection volume 

and capacity of the geology to handle the rate of injection; as well as 

minimizing the number of surface sites to achieve the desired injection volume 

and rate. 

Individual Response: In the 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. 

Letter ID: 0141 Comment ID: 23114 Letter Lines: 229 to 233 

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

comment) 

Comment: 3.We recommend that specifics of the site, as well as fluid and geologic 

characteristics, dictate the materials used in well construction, particularly 

whether stainless steel is really appropriate. We suspect Grade 316 stainless 

may not always be appropriate or necessary especially when considering 

conversion of EOR wells to GS duty. 

Individual Response: EPA clarifies that Grade 316 stainless steel is not a specified material. It 

is discussed in the preamble to the proposed rule as an example of materials that have been used 

successfully in similar situations. The determination of the best material to use is left for the 

Director to approve based upon case-specific information as provided under §146.86(b)(1). 

18
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: 0141 Comment ID: 23115 Letter Lines: 235 to 236 

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

Comment: 4.Certainly acid resistant cement represents a modest cost for the benefit of 

long term well integrity. 

Individual Response: EPA acknowledges the comment and agrees that cement that is 

compatible with the CO2 and formation fluids will enhance Class VI well integrity. EPA also 

agrees that developing technology in the field of acid-resistant cement will provide the industry 

with future benefits. In the interest of USDW protection, the Agency requires that the materials 

used in Class VI wells be compatible with fluids with which they may come in contact, as 

specified in §146.86(b)(1). 

EPA adds that the requirements at §146.86(b)(1) state that materials must meet or exceed 

standards developed for such materials by the American Petroleum Institute, ASTM 

International, or comparable standards acceptable to the Director. This requirement invokes the 

expertise of these bodies and allows the use of technologies that are yet to be developed. 

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: 0141 Comment ID: 23116 Letter Lines: 238 to 246 

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

Comment: Well Operation 

1.We do not believe that hydraulic fracturing should be restricted or prohibited 

where it can be demonstrated that existing faults are sufficiently remote from 

the injection site or the geology is otherwise appropriate for it. 

2.Similarly, we also believe that the geology itself can inform the siting 

process and application as to whether fracturing will be appropriate, even 

without existing faults in proximity to the well location. 

Individual Response: The final rule allows the use of hydraulic fracturing for purposes of Class 

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VI injection, where approved by the Director. Hydraulic fracturing is one of several stimulation 

technologies available to improve wellbore and formation injectivity. 

EPA agrees that site-specific information will inform the siting process and decisions about 

whether fracturing is appropriate. 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. 

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

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

pressure only during well stimulation. 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. EPA clarifies 

that UIC regulations prohibit fracturing of the confining zone at any time during injection or 

stimulation in order to protect USDWs from endangerment. 

Letter ID: 0141 Comment ID: 23117 Letter Lines: 248 to 251 

Comment Code: 4110 2.4.1.1 Injection pressure limitations 

Comment: 3.Injection pressure limitations, controlled by instrumentation, and monitored 

and recorded, are appropriate. We support the reasonableness of the suggested 90 

percent criteria as a pressure limitation. We also counsel reasonableness with 

respect to selecting what that pressure is. 

Individual Response: EPA agrees that the injection pressure should not exceed 90 percent of the 

fracture pressure of the injection zone. The final rule retains this provision at §146.88(a). EPA 

believes that the 90 percent requirement, which was suggested by IOGCC and permit writers 

whom EPA consulted when writing the regulation, is a satisfactory margin of safety for well 

operation necessary to protect USDWs from endangerment. 

Letter ID: 0141 Comment ID: 23118 Letter Lines: 253 to 254 

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

Comment: 4.We believe discretion afforded the states for implementation of this program 

is warranted. 

Individual Response: EPA agrees with commenters on the importance of allowing Directors 

discretion given the variety of geologic settings in which GS will be applied. EPA recognizes 

that State, Tribal, Territorial, and DI UIC Program Directors are in the best position to evaluate 

the unique issues related to well depth, geology, and hydrogeology that are posed by a Class VI 

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well. Some degree of flexibility is needed for Class VI wells because each decision made will be 

site-specific and conditions will differ from state to state. The GS rule balances the need for 

these site-specific decisions with the need for minimum standards to ensure national consistency. 

To ensure the final rule is applied consistently, EPA is developing guidance materials and plans 

to conduct on-line and in-person training for States, Tribes, and Territories that describe the 

process of applying for and receiving primary enforcement responsibility (primacy) for GS Class 

VI wells under Section 1422 of SDWA, as well as the technical and administrative issues related 

to developing GS regulations that are the equivalent of minimum Federal criteria and 

requirements. The guidance will be available at 

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

EPA is using an adaptive approach to regulating GS. 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. 

As part of its adaptive approach, if EPA finds that there is not sufficient consistency in the 

permits and that USDWs are not being sufficiently protected from endangerment, it will consider 

changes to the permit requirements in the future. 

Letter ID: 0141 Comment ID: 23119 Letter Lines: 256 to 256 

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

Comment: 5.Automatic shutoff down hole, in addition to surface shut off, is appropriate. 

Individual Response: As described above, 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. 

Letter ID: 0141 Comment ID: 23120 

Comment: Individual Response: 

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Letter ID: 0141 Comment ID: 23121 Letter Lines: 258 to 260 

Comment Code: 4546 2.5.2.2 MIT frequency (seeking comment) 

Comment Code: 4700 2.7 Proposed Recordkeeping and Reporting Requirements (40 CFR 

146.91) 

Comment: 6.We support mechanical integrity testing and monitoring, in some respects (on a 

continuous basis). Sensors and data logging is readily available. Semi-annual 

reporting, along with other reporting requirements, is also quite reasonable. 

Individual Response: EPA agrees with the commenter regarding the importance of 

demonstrating internal mechanical integrity (MI). EPA agrees with the commenter that 

continuous pressure monitoring of GS wells, instead of periodic testing, which is required for 

most other types of deep injection wells is appropriate because the potentially corrosive nature of 

CO2 injectate streams in the presence of water enables the immediate identification of corrosionrelated internal mechanical integrity problems that could lead to significant well problems and 

failure. 

Continuous monitoring was found to be very important in an EPA study of UIC Class I internal 

MIT failure rates and causes (USEPA 1993). The study reviewed MIT results over a 5 year 

period and found 135 MIT failures in 428 wells (a single well can have more than one MIT 

failure). In all cases, the MIT failures were found through continuous annulus monitoring which 

served the important role of an early warning to prevent any well failure. Class VI injection wells 

will be equipped with dedicated computer-based continuous pressure monitoring devices in 

concert with the shut-off systems required for GS wells, which typically take readings several 

times per second and record them electronically in a computer system. §146.91(a)(2) requires 

that monthly averages of the continuous annulus monitoring be reported on a semiannual basis. 

EPA is retaining the semi-annual reporting requirement in the final rule at §146.91(a) in order to 

ensure that permitting authorities can maintain proper oversight of GS projects, particularly in 

the early stages of rule implementation and deployment of GS technologies. The Agency also 

clarifies that permitting authorities may choose to require more frequent reporting, at the 

discretion of the Director. 

Letter ID: 0141 Comment ID: 23122 Letter Lines: 262 to 266 

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

USDW 

Comment: Proximity to USDW 

1.State discretion to decide whether injection below the lower most USDW is 

necessary. It is reasonable that certain combinations of geologic strata can 

readily protect a USDW from above not just from below. 

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

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23

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. 

Determinations regarding the appropriateness of an injection depth waiver would be made by the 

Director, based on site-specific information. 

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.