This comment letter response contains two parts:   

(1) The original submittal from the commenter.

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

Notes about the response letters:

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

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

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

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

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

individual response. These are described and explained below.  

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

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

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

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

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

appropriately addressed.

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

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

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

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

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

construction requirements).  

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

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

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

commenter was given a unique response.

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

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

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

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

and attention to each comment letter that was submitted.   

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

Responses on each topic area are compiled and are also available in the rulemaking docket.
COMMENTS OF THE 

NEW YORK STATE DEPARTMENT OF ENVIRONMENTAL CONSERVATION 

DIVISION OF MINERAL RESOURCES 

ON THE 

U.S. ENVIRONMENTAL PROTECTION AGENCY’S 

PROPOSED FEDERAL REQUIREMENTS UNDER THE UNDERGROUND 

INJECTION CONTROL PROGRAM FOR CARBON DIOXIDE GEOLOGIC 

SEQUESTRATION WELLS 

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

December 23, 2008 

The New York State Department of Environmental Conservation (NYSDEC) Division of 

Mineral Resources (DMN) submits the following comments to Docket ID No. EPA-HQOW-2008-0390 on the Environmental Protection Agency’s Proposed Federal 

Requirements for Carbon Dioxide (CO2) Geologic Sequestration (GS) Wells under the 

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

Submitter Information: Bradley J. Field, Director, Division of Mineral Resources, New 

York State Department of Environmental Conservation, 625 Broadway, Albany, New 

York 12233-6500 

Contact Information: If any additional information is needed regarding these 

comments, please contact Peter S. Briggs, Mineral Resources Specialist, Division of 

Mineral Resources, New York State Department of Environmental Conservation, (518) 

402-8056, psbriggs@gw.dec.state.ny.us 

1. General Comments 

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

primacy jurisdiction under the UIC program to administer CO2 storage 

regulatory activities. 

2. NYSDEC-DMN Response to EPA Narrative Proposal 

II. C. Who Implements the UIC Program? 

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

regulate the GS of CO2 and how these efforts might be used to better 

inform a final Federal rulemaking. 
NYSDEC-DMN Response: While the UIC program in New York State is 

directly implemented at this time, many other states currently have 

primacy jurisdiction and administer Class II and other wells. Primacy 

should be allowed solely for Class VI, and such should be structured to 

allow flexibility in the primacy process and defer to the state rule when it 

effectively meets the intent of the federal requirements. 

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

Program? 

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

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

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

depleted. 

NYSDEC-DMN Response: NYSDEC-DMN agrees with EPA’s proposed 

approach provided the project is an EOR project under Class II and the 

operator is able to demonstrate it as an ongoing viable EOR project. 

Operators should not be allowed to inject and store CO2 under the guise of 

a Class II EOR project to avoid Class VI permitting requirements. 

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

Program? 

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

‘‘grandfather’’ the construction requirements (e.g., permanent, 

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

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

determination that these wells would not endanger USDWs. 

NYSDEC-DMN Response: NYSDEC-DMN agrees that this discretion is 

appropriate and necessary when reviewing other UIC Class wells for use 

as UIC Class VI wells. 

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

Program? 

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

‘‘grandfather’’ the construction requirements for Class V experimental 

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

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

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

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

care and site closure).

2
NYSDEC-DMN Response: NYSDEC-DMN agrees that this discretion is 

appropriate and necessary when reviewing other UIC Class wells for use 

as UIC Class VI wells. 

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

Program? 

E. EPA seeks comment on the approach to grandfather construction 

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

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

additional construction requirements would be necessary to prevent 

endangerment to USDWs from the GS of CO2. 

NYSDEC-DMN Response: The Director should have the flexibility to 

determine whether a well meets federal Class VI protective standards on a 

well-by-well basis, and require the operator to adhere to the permitting 

process. 

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

Program? 

F. Additionally, EPA seeks comment on how the grandfathering 

approach for existing wells may affect compliance with the 

requirements in this proposal.

NYSDEC-DMN Response: The Director should have the flexibility to 

determine whether a well meets federal Class VI protective standards on a 

well-by-well basis, and require the operator to adhere to the permitting 

process. 

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

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

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

NYSDEC-DMN Response: While not a likelihood in New York due to the 

absence of coal in the state and typical depths to lowermost USDWs, 

NYSDEC-DMN believes there should not be any blanket prohibition 

against injection into any potentially approvable geologic zone even if it is 

above the lowermost USDW. There may be circumstances where this is 

appropriate and safe. The decision to permit a project should be made on 

a site-specific basis and evaluation. 

III. Proposed Regulatory Alternatives 

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

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

Requirements Approach) because it does not provide enough 

specificity to ensure that permitting authorities manage GS wells 

appropriately to prevent endangerment of USDWs. In addition, this 

alternative may be burdensome for owners or operators because of the 

potential for inconsistency across states and burdensome for permitting 

authorities who will likely be faced with developing their own 

technical approaches to regulating GS. 

NYSDEC-DMN Response: NYSDEC-DMN agrees that Regulatory 

Alternative 3, Tailored Requirements Approach is appropriate provided it 

allows discretion and flexibility on the part of the Director. 

III A. 1 Proposed Geologic Siting Requirements 

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

additional zones. 

NYSDEC-DMN Response: It is NYSDEC-DMN’s opinion that 

identification and characterization of secondary confinement should not be 

a requirement unless the unit identified as the primary confining zone is 

questionable. This determination should be made on a project and sitespecific basis. 

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

NYSDEC-DMN General Comment for Section III. A. 2: NYSDEC-DMN 

believes use of traditional well-specific AoR is problematic for 

comprehensive and adequate site characterization, and that EPA’s 

proposed approach is appropriate. 

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

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

NYSDEC-DMN Response: See General Comment for Section III. A. 2 

above. AoR delineation should be based on best available technology and 

available data. The collection of physical data (i.e., well bore data) may 

be necessary to fully use modeling to determine the ultimate extent of the 

proposed CO2 storage volume and reservoir pressures. The Director 

should have the flexibility to be able to supplement or substitute other data 

elements as appropriate ahead of such drilling and data gathering with 

confirmation of the model once additional information is available. 

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

4
K. EPA seeks comment on allowing the use of proprietary models for GS 

sites. 

NYSDEC-DMN Response: NYSDEC-DMN believes proprietary models 

should be allowed provided the Director has discretion to evaluate the 

accuracy of the modeling methodology. It should be noted that 

confidentiality of proprietary models will be subject to various 

jurisdictions and statutory limitations. 

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

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

models for delineating the AoR of GS sites. 

NYSDEC-DMN Response: See General Comment for Section III. A. 2 

above. AoR delineation should be based on best available technology and 

available data. The collection of physical data (i.e., well bore data) may 

be necessary to fully use modeling to determine the ultimate extent of the 

proposed CO2 storage volume and reservoir pressures. The Director 

should have the flexibility to be able to supplement or substitute other data 

elements as appropriate ahead of such drilling and data gathering with 

confirmation of the model once additional information is available. 

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

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

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

and the appropriateness of a 10 year minimum fixed frequency for 

AoR reevaluation. 

NYSDEC-DMN Response: AoR reevaluation frequency could be based 

on the amount of CO2 injected relative to the total proposed injection 

volume of CO2. For example, reevaluation of AoR could be required for 

every 20% injected but in no event less than every five years or at any 

other time at the discretion of the Director. Such a frequency would allow 

an operator to gather sufficient operating history and monitoring data for 

subsequent reevaluation. 

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

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

reevaluation of the AoR as well as the phased corrective action 

approach for GS wells. 

5
NYSDEC-DMN Response: Same as the two comments above for 

frequency of AoR reevaluation. With respect to the proposed phased 

corrective action approach for wells, NYSDEC-DMN agrees with the 

stated approach for the reasons given provided a permit can be suspended 

or revoked for failure to perform the corrective actions in a timely manner. 

However, NYSDEC-DMN believes all wells potentially impacted within 

the first five years of operation should be addressed prior to first injection 

of CO2. 

III A. 3 Proposed Injection Well Construction Requirements 

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

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

construction with a packer set opposite a cemented interval. 

NYSDEC-DMN Response: NYSDEC-DMN agrees with the need for 

adequate protection of USDWs and the proposed measures. However, 

Director discretion may be necessary to address site-specific conditions 

and the Director should be able to grant waivers to any requirement 

provided it can be demonstrated that such will not endanger USDWs. 

III A. 3 Proposed Injection Well Construction Requirements 

P. EPA also seeks comment on how the proposed grandfathering 

provisions for existing wells (construction requirements) may affect 

compliance with the above, proposed construction requirements. 

NYSDEC-DMN Response: NYSDEC-DMN believes that Director 

discretion is appropriate and necessary when reviewing other UIC Class 

wells for use as UIC Class VI wells. Overly prescriptive well 

construction requirements without any mechanism for deviation may limit 

the use of existing UIC wells and possible sequestration sites. 

III A. 3 Proposed Injection Well Construction Requirements 

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

techniques for GS wells and the applicability of well construction 

requirements discussed in this proposal. 

NYSDEC-DMN Response: NYSDEC-DMN believes the decision to use 

vertical, directional or horizontal wells should be left up to the operator. 

Horizontal wells should not be mandated. 

III A. 3 Proposed Injection Well Construction Requirements 

6
R. EPA seeks comment regarding requirements for degradation-resistant 

well construction materials, such as acid-resistant cements and 

corrosion resistant casing. 

NYSDEC-DMN Response: With regard to degradation-resistant well 

construction materials, the EPA rule should not be overly prescriptive but 

instead set performance standards that would allow case-by-case basis 

evaluation of casing and cementing materials necessary to meet the 

standards. 

III A. 4 Proposed Injection Well Operating Requirements 

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

hydraulic fracturing should be allowed during GS injection, and 

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

appropriate. 

NYSDEC-DMN Response: Hydraulic fracturing of wells in New York 

may be necessary in some cases to complete or recomplete an injection 

well. Any fracturing during well completion stimulation should be 

engineered so as to eliminate any risk of damage to confining zone(s). 

Other stimulation techniques should also be allowed provided there is no 

endangerment to USDWs. In addition, NYSDEC-DMN agrees with 

EPA’s position that an injection pressure safety factor be included in that 

the maximum allowable injection pressure during operational injection be 

limited to 90 percent of the fracture pressure of the injection zone. 

III A. 4 Proposed Injection Well Operating Requirements 

T. EPA is also requesting information to better qualify the use of 

fracturing for GS injection in specific geologic settings and rock 

formation lithologies. 

NYSDEC-DMN Response: As indicated above, engineered hydraulic 

fracturing of the injection zone should only be allowed during the initial 

completion or recompletion of a well. 

III A. 4 Proposed Injection Well Operating Requirements 

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

valves in GS wells. 

NYSDEC-DMN Response: Downhole shut-off valves, sometimes referred 

to as surface-controlled subsurface safety valves (SCSSV), should not be 

mandated in GS wells without further assessing the risk of wells without 

such (i.e., failure rate) and possible maintenance problems. It is 

7
NYSDEC-DMN’s understanding that SCSSVs are used in the offshore oil 

and gas industry primarily due to risks associated with maritime collision 

and hurricane events (i.e., ability to shut wells in downhole before 

platform evacuation). SCSSV are also part of an offshore facility’s 

emergency shutdown system. Nevertheless, at Director discretion, 

SCSSVs may provide an extra level of protection in sensitive settings but 

should not be required for all projects without additional study. 

III A. 4 Proposed Injection Well Operating Requirements 

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

alternative approaches that would allow injection between and/or 

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

to be available for GS while preventing USDW endangerment. 

NYSDEC-DMN Response: While not a likelihood in New York State due 

to typical depths to lowermost USDWs, NYSDEC-DMN believes there 

should not be any blanket prohibition against injection into any potentially 

approvable geologic zone, even if it is above the lowermost USDW. 

There may be circumstances where this is appropriate and safe. The 

decision to permit a project should be made on a site-specific basis and 

evaluation. 

III A. 4 Proposed Injection Well Operating Requirements 

W. In summary, EPA is soliciting comment on whether CO2 injection 

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

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

of feet of intervening formations between the injection zone and the 

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

movement into adjacent USDWs.

NYSDEC-DMN Response: Injection criteria and the decision to permit a 

project should be made on a site-specific basis and evaluation. 

III A. 4 Proposed Injection Well Operating Requirements 

X. EPA is also requesting comments on whether aquifer exemptions 

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

what conditions should such aquifer exemptions be approved. 

NYSDEC-DMN Response: Aquifer exemptions under Class VI should be 

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

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

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

8
III A. 4 Proposed Injection Well Operating Requirements 

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

minimum injection depth requirement for CO2 GS, rather than require 

that such injection take place below the lowermost USDW. 

NYSDEC-DMN Response: It is NYSDEC-DMN’s opinion that the EPA 

should not set a minimum injection depth requirement for CO2 GS 

operations. The decision to permit a project should be made on a sitespecific basis and evaluation. 

III A. 4 Proposed Injection Well Operating Requirements 

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

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

relate to USDWs. 

NYSDEC-DMN Response: Use of tracers in CO2 GS operations should 

not be routinely required although such should be an optional 

methodology for use at Director discretion. The shortcomings of routine 

use of tracers for GS operations were discussed at length at the February 

2008 EPA stakeholder workshop. 

III A. 5 Proposed Mechanical Integrity Testing Requirements 

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

NYSDEC-DMN Response: NYSDEC-DMN supports EPA’s proposal to 

require operators of GS projects to monitor internal mechanical integrity 

by continuously monitoring injection pressure, flow rate, and injected 

volumes, as well as annular pressure and fluid volume to provide early 

detection of anomalies that may indicate an internal leak. However, an 

“alarm” should shut in the well at the surface rather than requiring the 

installation and use of a downhole shut-off valve. 

III A. 5 Proposed Mechanical Integrity Testing Requirements 

BB. EPA seeks comment on the appropriate frequency of internal and 

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

and how to optimize MIT methods for GS. 

NYSDEC-DMN Response: As stated above, NYSDEC-DMN supports 

continuous monitoring of internal mechanical integrity for GS injection 

wells. For external MITs, the frequency should be more or less annually 

depending upon the specific circumstances. The types of tests allowed 

should be those appropriate under the specific circumstances. 

9
III A. 6 Proposed Plume and Pressure Front Monitoring Requirements 

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

for the purpose of tracking the location of the CO2 plume and 

associated pressure front over time. 

NYSDEC-DMN Response: NYSDEC-DMN is in favor of the EPA 

requiring an operator to conduct ongoing and sufficient monitoring to 

allow the tracking the CO2 plume and associated pressure front. In 

addition to any regular reporting frequency, an operator should be required 

to provide notification whenever actual conditions vary significantly from 

modeled predictions. 

III A. 6 Proposed Plume and Pressure Front Monitoring Requirements 

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

testing for GS wells. 

NYSDEC-DMN Response: NYSDEC-DMN is unclear as to the actual 

utility of pressure fall-off testing for operational GS wells. Instead of 

being mandated at least once every five years, the Director should have 

the discretion to require such testing as deemed appropriate. 

III A. 6 Proposed Plume and Pressure Front Monitoring Requirements 

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

the plume and pressure front is an important companion step to 

address any uncertainties associated with initial AoR modeling and 

requests comment on this approach and more efficient alternatives that 

may be used to track the plume and pressure front. 

NYSDEC-DMN Response: NYSDEC-DMN agrees that tracking of the 

CO2 plume and pressure front is important and should be required. 

However, the exact methodology should not be specified but determined 

on a site-specific basis. NYSDEC-DMN also agrees with EPA’s 

statement “As such, allowing flexibility in choosing the plume tracking 

methods and other monitoring technologies may provide an appropriate 

balance between the protective nature of indirect monitoring and cost 

considerations, as well as allowing for the adoption of continuously 

advancing technology.” 

III A. 6 Proposed Plume and Pressure Front Monitoring Requirements 

FF. EPA seeks comment on the appropriate amount and types of 

monitoring that should be conducted at a GS site. 

10
NYSDEC-DMN Response: NYSDEC-DMN agrees with EPA’s proposal 

to require operators to report semi-annually on the characteristics of 

injection fluids, injection pressure, flow rate, temperature, volume and 

annular pressure, and on the results of MITs, ground water monitoring, 

and any required atmospheric/soil gas monitoring. However, the amount 

and types of monitoring to be required should be site specific. 

III A. 6 Proposed Plume and Pressure Front Monitoring Requirements 

GG. Specifically, EPA seeks comment regarding the usefulness of 

indirect geophysical monitoring and surface air and soil gas 

monitoring. 

NYSDEC-DMN Response: NYSDEC-DMN agrees with EPA’s proposal 

to require operators to report semi-annually on the characteristics of 

injection fluids, injection pressure, flow rate, temperature, volume and 

annular pressure, and on the results of MITs, ground water monitoring, 

and any required atmospheric/soil gas monitoring. However, the amount 

and types of monitoring that are required should be site specific. Certain 

geophysical monitoring techniques that successfully monitor plume 

migration in the southern states may not have any monitoring capability in 

northern Paleozoic basins. 

III A. 6 Proposed Plume and Pressure Front Monitoring Requirements 

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

NYSDEC-DMN Response: The Director should be given flexibility to 

approve site-specific monitoring plans. 

III A. 7 Proposed Recordkeeping and Reporting Requirements 

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

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

application. 

NYSDEC-DMN Response: NYSDEC-DMN believes monitoring and 

testing plans, an AoR and corrective action plan, and a post-injection site 

care and site closure plan are integral components of any GS application, 

and should be required by the EPA. 

III A. 7 Proposed Recordkeeping and Reporting Requirements 

11
JJ. EPA seeks comment on the frequency of all proposed reporting 

requirements. 

NYSDEC-DMN Response: NYSDEC-DMN supports all stated reporting 

frequencies and requirements. 

III A. 7 Proposed Recordkeeping and Reporting Requirements 

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

today’s proposed rule. 

NYSDEC-DMN Response: NYSDEC-DMN agrees with electronic 

submittal in principle as long as there is sufficient flexibility to allow 

states to utilize existing or preferred state data processing systems or 

software. At this time, electronic reporting should be an option but not a 

requirement. 

III A. 7 Proposed Recordkeeping and Reporting Requirements 

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

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

an annual report. 

NYSDEC-DMN Response: NYSDEC-DMN agrees with the concept and 

sees the merits of requiring an annual report that provides a narrative 

analysis of GS operations in addition to requiring semi-annual reporting of 

data. 

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

Requirements 

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

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

based on monitoring and modeling data. 

NYSDEC-DMN Response: Given that current injection and reservoir 

behavior data demonstrates a decreasing risk of leakage after injection 

ceases, NYSDEC-DMN believes that a 50-year default time frame for 

post-injection site care is too long and that a 30-year starting period may 

be more appropriate to allow GS projects to move forward. It would be 

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

vice versa, as such would better facilitate project planning. Regardless, it 

is critical that the Director have the discretion to increase or decrease the 

period based on the specifics of a particular project. 

12
III A. 8 Proposed Well Plugging, Post-Injection site Care, and Site Closure 

Requirements 

NN. EPA is requesting comments on the proposed requirements for 

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

proposed requirements for the post-injection time period. 

NYSDEC-DMN Response: Given that current injection and reservoir 

behavior data demonstrates a decreasing risk of leakage after injection 

ceases, NYSDEC-DMN believes that a 50-year default time frame for 

post-injection site care is too long and that a 30-year starting period may 

be more appropriate to allow GS projects to move forward. It would be 

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

vice versa, as such would better facilitate project planning. Regardless, it 

is critical that the Director have the discretion to increase or decrease the 

period based on the specifics of a particular project. 

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

Requirements 

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

be allowed to shorten the timeframe based on performance 

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

NYSDEC-DMN Response: Given that current injection and reservoir 

behavior data demonstrates a decreasing risk of leakage after injection 

ceases, NYSDEC-DMN believes that a 50-year default time frame for 

post-injection site care is too long and that a 30-year starting period may 

be more appropriate to allow GS projects to move forward. It would be 

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

vice versa, as such would better facilitate project planning. Regardless, it 

is critical that the Director have the discretion to increase or decrease the 

period based on the specifics of a particular project. 

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

PP. EPA is requesting comments on whether financial responsibility 

mechanisms to be recommended in EPA guidance should be adjusted 

in the manner described, whether additional instruments should be 

included, and whether other adjustments to the financial responsibility 

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

the SDWA. 

NYSDEC-DMN Response: The EPA proposed rule for financial assurance 

appears to be adequate with respect to wells and NYSDEC-DMN 

13
understands that any well plugging financial instrument would be released 

upon proper plugging and abandonment of the well. It is also understood 

that a second tier of financial assurance, that could be filed at a later date 

(i.e., closer to ceasing injection), is being considered for post-injection site 

care. However, according to the proposed rule, both forms of financial 

assurance would be limited to SDWA authority which does not extend to 

financial responsibility for activities unrelated to protection of USDWs 

(e.g., coverage of risks to air, ecosystems, or public health unrelated to 

USDW endangerment). Because of EPA’s focused authority under the 

SDWA for the UIC program, action by individual states may be required 

to fill any financial assurance and regulatory gaps. 

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

QQ. The Agency is also requesting comment on allowing separate 

financial demonstrations to be submitted for the plugging of the 

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

NYSDEC-DMN Response: EPA’s proposal for financial assurance 

appears to be adequate with respect to wells and NYSDEC-DMN 

understands that any well plugging financial instrument would be released 

upon proper plugging and abandonment of the well. It is also understood 

that a second tier of financial assurance, that could be filed at a later date 

(i.e., closer to ceasing injection), is being considered for post-injection site 

care. EPA states that it is considering requiring well plugging financial 

demonstration at permit issuance and post-injection site care financial 

security demonstration at a later time (e.g., within 180 days of notifying 

the Director that the well will be plugged and abandoned). EPA also 

states “Trying to determine the cost for post-injection site care, possibly 

30 to 50 years in the future, could be difficult, as could the approval of a 

financial demonstration.” It is NYSDEC-DMN’s opinion that some level 

of financial assurance for post-site injection care should be in place at first 

injection of CO2. If there are concerns with uncertainty and overly 

burdening an operator, perhaps the amount of post-injection site care 

assurance could start with a basic level of protection and be required to be 

increased as the potentially affected area grows over time with additional 

injection. 

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

Decisions for GS Projects? 

RR. EPA requests comment on adopting the existing requirements for 

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

whether additional requirements should be included to reflect the 

availability of new tools for disseminating and gathering information. 

14
15

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

technology. 

NYSDEC-DMN Response: All states have public notice laws and 

regulations that cover most regulatory and permitting functions. These 

laws and regulations would extend to the permitting and the regulation of 

GS that require public notice, hearings and due process to all affected 

parties. This should be adequate for public involvement purposes. 

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

Class VI Wells? 

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

of allowing primacy approval for Class VI wells independent of other 

well classes. 

NYSDEC-DMN Response: NYSDEC-DMN supports the creation of a 

separate class VI for GS wells and strongly supports allowing state 

primacy solely for Class VI. In addition, states should have the authority 

to designate which agency in the state can apply for and be granted 

primacy. 

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

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

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

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

this approach. 

NYSDEC-DMN Response: NYSDEC-DMN agrees with the EPA 

proposal. 

 
Letter ID: 0186 

Commenter: Bradley J. Field 

Organization: New York State Dept. of Environmental Conservation Div. of Mineral Resources 

Letter ID: 0186 Comment ID: 25170 Letter Lines: 44 to 46 

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

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

primacy jurisdiction under the UIC program to administer CO2 storage regulatory 

activities. 

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

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

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

unique technical challenges associated with GS. 

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

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

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

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

matching requirement. 

Letter ID: 0186 Comment ID: 25171 Letter Lines: 52 to 61 

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

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

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

rulemaking. 

NYSDEC-DMN Response: While the UIC program in New York State is directly 

implemented at this time, many other states currently have primacy jurisdiction 

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

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

process and defer to the state rule when it effectively meets the intent of the 

federal requirements. 

Individual Response: EPA agrees with commenters that states should be allowed to obtain 

primacy for Class VI wells independently of other well classes, and will allow independent 

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

(encompassing capture, transportation, and geologic sequestration) to be an important part of a 

national priority to address climate change, EPA believes that providing states the flexibility to 

obtain primacy for Class VI wells independently of other well classes can help foster effective 

1
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. 

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. 

Letter ID: 0186 Comment ID: 25172 Letter Lines: 66 to 74 

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

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

and GS prior to the field being completely depleted. 

NYSDEC-DMN Response: NYSDEC-DMN agrees with EPA’s proposed approach provided the 

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

it as an ongoing viable EOR project. Operators should not be allowed to inject 

and store CO2 under the guise of a Class II EOR project to avoid Class VI 

permitting requirements. 

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

2
oil and gas recovery should remain under the Class II Program. EPA agrees that the nature and 

risks of CO2 injection for long term storage is different from Class II CO2 injection for ER, and 

that tailored requirements for GS wells are appropriate and necessary to protect USDWs from 

endangerment. For this reason, the Agency tailored UIC requirements for Class VI wells that 

address the general risks deep injection may pose to USDWs and specifically address the unique 

nature of CO2 GS (i.e., very large volumes, very long time-periods, and reservoir pressure 

conditions). 

EPA agrees and clarifies that the final Class VI regulations require that any owner or operator 

injecting CO2 for the primary purpose of long term storage obtain a Class VI permit with some 

special consideration for the fact that they are transitioning from a well not originally designed to 

meet Class VI requirements. The Director has the authority to determine at what point a Class VI 

permit is required for those projects that are transitioning from the primary purpose of EOR to 

long term storage of CO2. The final regulation provides a set of technical factors for the Director 

to evaluate in making this determination, at §144.19. EPA believes that this approach provides 

sufficient protection of USDWs when there is an increased risk to USDWs as compared to 

traditional Class II operations while allowing for site-specific flexibility. 

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

will assist Directors in 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. 

Letter ID: 0186 Comment ID: 25173 Letter Lines: 79 to 86 

Comment Code: 2062 1.5.3.1 Grandfathering construction of Class I wells (seeking comment) 

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

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

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

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

CO2, provided he/she is able to make a determination that these wells would not 

endanger USDWs. 

NYSDEC-DMN Response: NYSDEC-DMN agrees that this discretion is appropriate and 

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

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 

3
to meet the requirements at §146.86(a) and ensure protection of USDWs, in lieu of requirements 

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

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

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

Letter ID: 0186 Comment ID: 25174 Letter Lines: 91 to 99 

Comment Code: 2066 1.5.3.3 Grandfathering construction of Class V wells (seeking comment) 

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

"grandfather" the construction requirements for Class V experimental wells 

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

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

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

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

NYSDEC-DMN Response: NYSDEC-DMN agrees that this discretion is appropriate and 

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

Individual Response: EPA agrees that many Class V experimental technology wells are 

designed and constructed to withstand exposure to CO2. The final GS rule provides for the 

construction of these wells to be grandfathered per §146.81(c), provided the owner or operator 

can demonstrate to the Director that the wells were engineered and constructed to meet the 

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

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

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

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

Letter ID: 0186 Comment ID: 25175 Letter Lines: 104 to 112 

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

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

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

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

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

CO2. 

NYSDEC-DMN Response: The Director should have the flexibility to determine 

whether a well meets federal Class VI protective standards on a well-by-well 

basis, and require the operator to adhere to the permitting process. 

Individual Response: EPA believes that a cautious approach to grandfathering is appropriate, 

particularly given that the converted well will be used for a substantially different process, which 

4
involves increased reservoir pressures associated with large volumes of stored CO2 and the 

corrosivity of CO2 in the presence of water. The final GS rule provides for the construction of 

these wells to be grandfathered (per 146.81(c)). EPA has included a requirement in the final GS 

rule that owners or operators seeking to convert existing wells for long term storage must 

demonstrate to the Director that the grandfathered wells were engineered and constructed meet 

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

§146.86(b) and §146.87(a). Conversion of the well is at the Director's discretion following an 

evaluation of all other site-specific information about the well and the project, e.g., modeling, 

monitoring, and other data. Any wells that have deteriorated due to contact with incompatible 

injected or formation fluids may not be approved for conversion. 

Letter ID: 0186 Comment ID: 25176 Letter Lines: 117 to 122 

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

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

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

NYSDEC-DMN Response: The Director should have the flexibility to determine 

whether a well meets federal Class VI protective standards on a well-by-well 

basis, and require the operator to adhere to the permitting process. 

Individual Response: EPA believes that a cautious approach to grandfathering is appropriate, 

particularly given that the converted well will be used for a substantially different process, which 

involves increased reservoir pressures associated with large volumes of stored CO2 and the 

corrosivity of CO2 in the presence of water. The final GS rule provides for the construction of 

these wells to be grandfathered (per 146.81(c)). EPA has included a requirement in the final GS 

rule that owners or operators seeking to convert existing wells for long term storage must 

demonstrate to the Director that the grandfathered wells were engineered and constructed meet 

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

§146.86(b) and §146.87(a). Conversion of the well is at the Director's discretion following an 

evaluation of all other site-specific information about the well and the project, e.g., modeling, 

monitoring, and other data. Any wells that have deteriorated due to contact with incompatible 

injected or formation fluids may not be approved for conversion. 

Letter ID: 0186 Comment ID: 25177 Letter Lines: 126 to 134 

Comment Code: 2163 1.6.3.1 Comments in favor of injection into unmineable coal seams 

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

USDW 

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

into such formations if they are above the lowermost USDW. 

5
NYSDEC-DMN Response: While not a likelihood in New York due to the absence of 

coal in the state and typical depths to lowermost USDWs, NYSDEC-DMN believes 

there should not be any blanket prohibition against injection into any 

potentially approvable geologic zone even if it is above the lowermost USDW. 

There may be circumstances where this is appropriate and safe. The decision to 

permit a project should be made on a site-specific basis and evaluation. 

Individual Response: EPA agrees that GS into unmineable coal seams has the potential to allow 

sequestration while ensuring USDW protection from endangerment, as described by commenters 

citing the process of enhanced methane recovery. The final GS rule does not preclude injection 

into unmineable coal seams provided owners or operators can demonstrate that GS can be 

performed in a manner that protects USDWs from endangerment. The Agency clarifies that 

owners or operators of Class VI wells used for injecting CO2 into unmineable coal seams are 

subject to the same site characterization, well construction, operation, monitoring, post-injection 

site care and site closure requirements that are required of projects injecting into other formation 

types. 

EPA clarifies that the final rule requires that injection for GS be into non-USDWs below the 

lowermost USDW; however, owners or operators may apply for a waiver from this requirement, 

as described in §146.95. For more information, see the discussion of waivers in the preamble to 

the final rule. 

Letter ID: 0186 Comment ID: 25178 Letter Lines: 138 to 149 

Comment Code: 2300 1.7 Comments on the Alternatives Considered 

Comment: H. EPA is proposing Regulatory Alternative 3, the Tailored Requirements 

Approach. EPA did not select Alternative 1 (Non-Specific Requirements Approach) 

because it does not provide enough specificity to ensure that permitting 

authorities manage GS wells appropriately to prevent endangerment of USDWs. In 

addition, this alternative may be burdensome for owners or operators because of 

the potential for inconsistency across states and burdensome for permitting 

authorities who will likely be faced with developing their own technical 

approaches to regulating GS. 

NYSDEC-DMN Response: NYSDEC-DMN agrees that Regulatory Alternative 3, Tailored 

Requirements Approach is appropriate provided it allows discretion and 

flexibility on the part of the Director. 

Individual Response: EPA agrees with the commenters that Regulatory Alternative 3 is 

appropriate. The technical requirements in Alternative 3 (and the final GS rule) 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. 

6
Even though the Agency did not choose Alternatives 1 or 2, EPA agrees that flexibility is 

important to accommodate the varied conditions that may be encountered at GS sites while 

ensuring the protection of USDWs. The final GS regulation gives the Director discretion to set 

permit criteria that are appropriate to site-specific conditions. The regulation provides flexibility 

to select appropriate sites and target formations (under §146.82), well construction specifics 

(under §146.86), and testing and monitoring regimes (under §146.90), provided the owner or 

operator can demonstrate that the injection and storage will not endanger USDWs and that 

minimum requirements for the site are met. Commenters representing electric utilities, water 

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

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

Letter ID: 0186 Comment ID: 25179 Letter Lines: 153 to 159 

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

(seeking comment) 

Comment: I. EPA specifically seeks comment on the merits of identifying these additional 

zones. 

NYSDEC-DMN Response: It is NYSDEC-DMN’s opinion that identification and 

characterization of secondary confinement should not be a requirement unless the 

unit identified as the primary confining zone is questionable. This 

determination should be made on a project and site-specific basis. 

Individual Response: EPA agrees with the commenter that, in some situations, the presence of 

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

can improve USDW protection from endangerment. The final regulation retains the requirement 

at §146.83(b) which affords the Director discretion to require owners or operators to identify and 

characterize additional zones. 

Letter ID: 0186 Comment ID: 25180 Letter Lines: 161 to 165 

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

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

NYSDEC-DMN General Comment for Section III. A. 2: NYSDEC-DMN believes use of 

traditional well-specific AoR is problematic for comprehensive and adequate site 

characterization, and that EPA’s proposed approach is appropriate. 

Individual Response: EPA agrees that the unique aspects of GS merit the use of sophisticated 

computational modeling for delineation of the AoR, based on site-specific features and geology, 

including the presence of faults, fractures, and artificial penetrations. EPA believes that 

computational modeling of the AoR prior to injection will provide the best obtainable estimates 

7
of the extent of the CO2 plume over several years of active injection. EPA has strengthened the 

minimum frequency for the AoR reevaluation from ten years to 5 years (146.84(e)). 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. 

Letter ID: 0186 Comment ID: 25181 Letter Lines: 169 to 178 

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

comment) 

Comment: J. EPA seeks comment on the use of modeling for AoR delineation. 

NYSDEC-DMN Response: See General Comment for Section III. A. 2 above. AoR 

delineation should be based on best available technology and available data. The 

collection of physical data (i.e., well bore data) may be necessary to fully use 

modeling to determine the ultimate extent of the proposed CO2 storage volume and 

reservoir pressures. The Director should have the flexibility to be able to 

supplement or substitute other data elements as appropriate ahead of such 

drilling and data gathering with confirmation of the model once additional 

information is available. 

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

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

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

the proposed AoR and corrective action plan required at §146.84(b), to the satisfaction of the 

Director, that the modeled AoR will be based on detailed geologic data collected on the site. 

EPA anticipates that any model that does this in a satisfactory manner will be approved by the 

Director. EPA acknowledges that modeling technology is expected to continuously improve, and 

encourages and expects owners or operators to use the best available multiphase computational 

models to determine the AoR. Reliance on improved models will likely increase the accuracy 

and quality of the AoR characterization, resulting in better protection of USDWs from 

endangerment. 

Letter ID: 0186 Comment ID: 25182 Letter Lines: 182 to 187 

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

Comment: K. EPA seeks comment on allowing the use of proprietary models for GS sites. 

NYSDEC-DMN Response: NYSDEC-DMN believes proprietary models should be allowed 

provided the Director has discretion to evaluate the accuracy of the modeling 

methodology. It should be noted that confidentiality of proprietary models will 

be subject to various jurisdictions and statutory limitations. 

8
Individual Response: EPA agrees that some of the available proprietary models may meet the 

needs for calculating the AoRs of GS sites. EPA will allow their use in meeting the requirements 

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

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

basis. Information including model assumptions and equations are used by the Director to inform 

his/her decision to issue the permit and ensure that the requirements are met and the GS well will 

not endanger USDWs. EPA adds that its Confidential Business Information requirements at 40 

CFR 144.5 will apply to the use of proprietary models. 

Letter ID: 0186 Comment ID: 25183 Letter Lines: 191 to 201 

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

comment) 

Comment: L. EPA seeks comment on the applicability of computational fluid flow models for 

delineating the AoR of GS sites. 

NYSDEC-DMN Response: See General Comment for Section III. A. 2 above. AoR 

delineation should be based on best available technology and available data. The 

collection of physical data (i.e., well bore data) may be necessary to fully use 

modeling to determine the ultimate extent of the proposed CO2 storage volume and 

reservoir pressures. The Director should have the flexibility to be able to 

supplement or substitute other data elements as appropriate ahead of such 

drilling and data gathering with confirmation of the model once additional 

information is available. 

Individual Response: As described above, EPA agrees that it is appropriate to allow operators 

the flexibility to select modeling, site characterization, and monitoring techniques that are most 

appropriate to site conditions and available types and amounts of data. The owner or operator 

must demonstrate, in the proposed AoR and corrective action plan required at §146.84(b), to the 

satisfaction of the Director, that the modeled AoR will be based on detailed geologic data 

collected on the site. EPA adds that the Director has authority to request supplemental 

information if needed to ensure that the site will be protective of USDWs. 

Letter ID: 0186 Comment ID: 25184 Letter Lines: 205 to 214 

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

Comment Code: 3560 2.2.3.2 Conditions that merit reevaluation of the AoR (seeking comment) 

Comment: M. EPA seeks comment on requiring the reevaluation of the site AoR on a periodic 

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

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

NYSDEC-DMN Response: AoR reevaluation frequency could be based on the amount of 

CO2 injected relative to the total proposed injection volume of CO2. For 

9
example, reevaluation of AoR could be required for every 20% injected but in no 

event less than every five years or at any other time at the discretion of the 

Director. Such a frequency would allow an operator to gather sufficient 

operating history and monitoring data for subsequent reevaluation. 

Individual Response: EPA disagrees with the commenter's suggestion to tie the AoR 

reevaluation frequency to the volume or percentage of CO2 injected. EPA believes that it is 

important to set an AoR reevaluation frequency (i.e., at least every five years) to ensure that the 

project is reviewed and any necessary updates to the project plans or the permit are made on a 

regular schedule, regardless of the pace at which the injection is completed. 

EPA believes that the commenter's proposed approach has the potential to lead to AoR 

reevaluation schedules that are not sufficiently frequent to ensure protection of USDWs from 

endangerment, if for some reason the variables (rate or volume) are such that reevaluation based 

on percentages are not triggered within 5 years. In addition, EPA believes this approach may 

complicate the administrative process of determining and tracking the reevaluation schedule. 

For this reason, EPA has, at §146.84(e), adopted the 5 year interval (an adjustment from the ten 

year interval in the proposed rule) recommended by many commenters. EPA adds that the 

Director has discretion to require reevaluation more frequently, such as when monitoring data 

differ significantly from modeled predictions, or when there are appreciable operational changes 

(e.g., injection rates). 

Letter ID: 0186 Comment ID: 25185 Letter Lines: 218 to 227 

Comment Code: 3630 2.2.4.1 Comments in favor of allowing phased corrective action 

Comment: N. EPA invites public comment on the merits and frequency of reevaluation of the 

AoR as well as the phased corrective action approach for GS wells. 

NYSDEC-DMN Response: Same as the two comments above for frequency of AoR 

reevaluation. With respect to the proposed phased corrective action approach for 

wells, NYSDEC-DMN agrees with the stated approach for the reasons given provided 

a permit can be suspended or revoked for failure to perform the corrective 

actions in a timely manner. However, NYSDEC-DMN believes all wells potentially 

impacted within the first five years of operation should be addressed prior to 

first injection of CO2. 

Individual Response: EPA agrees that corrective action on wells should be completed several 

years in advance of the anticipated arrival of the CO2 plume or pressure front. However, EPA 

does not believe that it is appropriate to set a specific time for completing corrective action in the 

regulation due to uncertainty in delineating the CO2 plume movement during certain time 

frames. Instead, such decisions would be incorporated into the AoR and corrective action plan 

for each project, as specified in §146.84(b)(2)(iv), which would be developed by the owner or 

operator and approved by the Director based on the geology of the site and the wells in the AoR. 

10
All needed corrective action (whether phased or not) must be performed by the owner or 

operator as described in the approved AoR and corrective action plan and on the approved 

schedule to ensure that deficient wells in the AoR are addressed in a timely manner; failure to do 

so will either preclude authorization to inject or, in the case of phased corrective action, be 

considered a violation of the permit and subject to applicable civil, criminal, or administrative 

penalties under SDWA §1423. 

Letter ID: 0186 Comment ID: 25186 Letter Lines: 231 to 239 

Comment Code: 3800 2.3 Proposed Injection Well Construction Requirements (40 CFR 

146.86) 

Comment: O. EPA seeks comment on the proposed GS well requirements for depth of surface 

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

opposite a cemented interval. 

NYSDEC-DMN Response: NYSDEC-DMN agrees with the need for adequate protection of 

USDWs and the proposed measures. However, Director discretion may be necessary 

to address site-specific conditions and the Director should be able to grant 

waivers to any requirement provided it can be demonstrated that such will not 

endanger USDWs. 

Individual Response: EPA agrees that a flexible approach to the construction of Class VI wells 

is appropriate, and believes the rule provides an appropriate amount of flexibility. The 

construction requirements at §146.86 provide flexibility by listing the basic components a Class 

VI well must have to prevent endangerment of USDWs, and allow owners or operators to choose 

appropriate materials in meeting these requirements. However, EPA notes that the Director may 

not waive any construction requirement unless the regulation specifically gives the Director such 

discretion for a particular requirement (e.g., §146.83(b)(4) allows the Director to approve 

alternative methods of cementing in some circumstances). 

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

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

§146.86(b)(1). 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: 0186 Comment ID: 25187 Letter Lines: 243 to 251 

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

Comment Code: 3800 2.3 Proposed Injection Well Construction Requirements (40 CFR 

146.86) 

11
Comment: P. EPA also seeks comment on how the proposed grandfathering provisions for 

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

proposed construction requirements. 

NYSDEC-DMN Response: NYSDEC-DMN believes that Director discretion is appropriate 

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

wells. Overly prescriptive well construction requirements without any mechanism 

for deviation may limit the use of existing UIC wells and possible sequestration 

sites. 

Individual Response: As described above, conversion of the well would be at the Director's 

discretion following an evaluation of all other site-specific information about the well and the 

project, e.g., modeling, monitoring, and other data. Any wells that have deteriorated due to 

contact with incompatible injected or formation fluids may not be approved for conversion. 

EPA believes that, given the range of types of existing wells that may be candidates for 

conversion, flexibility is appropriate regarding conversion of Class I, II, or V wells for GS, 

provided it can be demonstrated to the Director's satisfaction that the converted well can conduct 

GS operations in a manner that does not endanger USDWs. The final GS rule, at §146.81(c), 

allows the construction of these wells to be grandfathered, 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). Only the cemented-in-place construction requirements would be 

grandfathered under the final GS rule; following conversion, these wells must be permitted as 

Class VI wells and be subject to the operational, MIT, monitoring, reporting, plugging, and postinjection site care and site closure requirements in the final GS rule. 

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

guidance will assist Directors and owner/operators in evaluating where a project may fit within a 

Class II to Class VI transition. The guidance describes the methods available for the Director to 

determine the risk posed to USDWs from a GS/ER project, and how the Director may determine 

if a project should be regulated by a Class II or Class VI UIC program. The guidance will be 

available on EPA's web site, at 

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

Letter ID: 0186 Comment ID: 25188 Letter Lines: 255 to 261 

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

Comment: Q. EPA seeks comment on the merits of horizontal well drilling techniques for GS 

wells and the applicability of well construction requirements discussed in this 

proposal. 

NYSDEC-DMN Response: NYSDEC-DMN believes the decision to use vertical, 

directional or horizontal wells should be left up to the operator. Horizontal 

12
wells should not be mandated. 

Individual Response: In the final rule, EPA allows the use of but does not mandate 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: 0186 Comment ID: 25189 Letter Lines: 265 to 272 

Comment Code: 3860 2.3.3 Well component degradation 

Comment: R. EPA seeks comment regarding requirements for degradation-resistant well 

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

casing. 

NYSDEC-DMN Response: With regard to degradation-resistant well construction 

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

performance standards that would allow case-by-case basis evaluation of casing 

and cementing materials necessary to meet the standards. 

Individual Response: EPA clarifies that acid-resistant cement is not specifically required in a 

Class VI injection well. Rather, as stated in §146.86(b)(1), casings and cement used must have 

sufficient strength and be designed for the life of the sequestration project. Further, materials 

must meet standards listed in the rule and be compatible with fluids with which the materials 

may be expected to come into contact. Therefore, some well materials may need to be acidresistant and some may not if they do not come in contact with the CO2 stream or other corrosive 

fluids and if approved by the Director. 

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: 0186 Comment ID: 25190 Letter Lines: 276 to 284 

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

comment) 

Comment: S. EPA is requesting comment on the extent and scope to which hydraulic 

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

13
fracturing for the purposes of well stimulation is appropriate. 

NYSDEC-DMN Response: Hydraulic fracturing of wells in New York may be necessary 

in some cases to complete or recomplete an injection well. Any fracturing during 

well completion stimulation should be engineered so as to eliminate any risk of 

damage to confining zone(s). Other stimulation techniques should also be allowed 

provided there is no endangerment to USDWs. In addition, NYSDEC-DMN agrees with 

Individual Response: The final GS regulation allows hydraulic fracturing only during Class VI 

well stimulation. Section 146.88(a) permits injection pressure to exceed 90 percent of the 

fracture pressure only during well stimulation. EPA acknowledges that in some circumstances 

hydraulic fracturing during a well workover may be appropriate. The final rule at §146.91(d)(2) 

includes a requirement that the owner or operator notify the Director 30 days before performing 

stimulation during the operational phase of a GS project; this will provide an additional 

opportunity for the Director to review the owner or operator's plans for stimulation and add other 

requirements as needed. EPA clarifies that UIC regulations prohibit fracturing of the confining 

zone at any time during injection or stimulation in order to protect USDWs from endangerment. 

Letter ID: 0186 Comment ID: 25191 Letter Lines: 284 to 287 

Comment Code: 4110 2.4.1.1 Injection pressure limitations 

Comment: provided there is no endangerment to USDWs. In addition, NYSDEC-DMN agrees 

with 

EPA’s position that an injection pressure safety factor be included in that the 

maximum allowable injection pressure during operational injection be limited to 

90 percent of the fracture pressure of the injection zone. 

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 State representatives whom 

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

operation necessary to protect USDWs from endangerment. 

Letter ID: 0186 Comment ID: 25192 Letter Lines: 291 to 296 

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

comment) 

Comment: T. EPA is also requesting information to better qualify the use of fracturing 

for GS injection in specific geologic settings and rock formation lithologies. 

NYSDEC-DMN Response: As indicated above, engineered hydraulic fracturing of the 

injection zone should only be allowed during the initial completion or 

recompletion of a well. 

14
Individual Response: The final GS regulation allows hydraulic fracturing only during Class VI 

well stimulation. Section 146.88(a) permits injection pressure to exceed 90 percent of the 

fracture pressure only during well stimulation. EPA acknowledges that in some circumstances 

hydraulic fracturing during a well workover may be appropriate. The final rule at §146.91(d)(2) 

includes a requirement that the owner or operator notify the Director 30 days before performing 

stimulation during the operational phase of a GS project; this will provide an additional 

opportunity for the Director to review the owner or operator's plans for stimulation and add other 

requirements as needed. EPA clarifies that UIC regulations prohibit fracturing of the confining 

zone at any time during injection or stimulation. 

Letter ID: 0186 Comment ID: 25193 Letter Lines: 300 to 312 

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

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

wells. 

NYSDEC-DMN Response: Downhole shut-off valves, sometimes referred to as surfacecontrolled subsurface safety valves (SCSSV), should not be mandated in GS wells 

without further assessing the risk of wells without such (i.e., failure rate) 

and possible maintenance problems. It is NYSDEC-DMN’s understanding that SCSSVs 

are used in the offshore oil and gas industry primarily due to risks associated 

with maritime collision and hurricane events (i.e., ability to shut wells in 

downhole before platform evacuation). SCSSV are also part of an offshore 

facility’s emergency shutdown system. Nevertheless, at Director discretion, 

SCSSVs may provide an extra level of protection in sensitive settings but should 

not be required for all projects without additional study. 

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. The Agency agrees with the commenter 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. 

While EPA acknowledges that the likelihood of damage to onshore facilities is lower than that 

for off-shore facilities, down-hole shut-off valves are still commonly used in onshore facilities 

such as acid gas injection wells and high pressure, high-temperature wells. While valve failure is 

a concern, EPA believes that technology has advanced sufficiently to make valve failure a rare 

occurrence and to appropriately handle such failure if it occurs. For example, wireline retrievable 

15
devices can allow repair or replacement of damaged devices without necessitating pulling the 

tubing. 

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) and 

automatic down-hole shut-off devices for offshore wells in submerged lands within the 

jurisdiction of a State ensures that proper precautions are taken to prevent subsurface fluid 

movement and ensure protection of USDWs. 

Letter ID: 0186 Comment ID: 25194 Letter Lines: 316 to 326 

Comment Code: 4410 2.4.4.3.1 Comments in favor of allowing injection above/between 

USDWs in certain circumstances 

Comment: V. As a result, the Agency is considering and requesting comment on alternative 

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

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

preventing USDW endangerment. 

NYSDEC-DMN Response: While not a likelihood in New York State due to typical 

depths to lowermost USDWs, NYSDEC-DMN believes there should not be any blanket 

prohibition against injection into any potentially approvable geologic zone, 

even if it is above the lowermost USDW. There may be circumstances where this is 

appropriate and safe. The decision to permit a project should be made on a sitespecific basis and evaluation. 

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

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

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

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

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

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

of formation. 

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

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

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

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

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

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

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

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

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

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

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

16
Determinations about the appropriateness of a waiver would be made by the Director, based on 

evaluation of site-specific conditions. For additional information on the waiver approach and 

aquifer exemptions for Class VI wells, please see the final rule and preamble, as well as EPA's 

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

Letter ID: 0186 Comment ID: 25195 Letter Lines: 330 to 337 

Comment Code: 4410 2.4.4.3.1 Comments in favor of allowing injection above/between 

USDWs in certain circumstances 

Comment: W. In summary, EPA is soliciting comment on whether CO2 injection should be 

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

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

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

exist that will prevent fluid movement into adjacent USDWs. 

NYSDEC-DMN Response: Injection criteria and the decision to permit a project 

should be made on a site-specific basis and evaluation. 

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

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

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

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

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

between USDWs, where approved by the Director, based on evaluation of site-specific 

conditions. 

Letter ID: 0186 Comment ID: 25196 Letter Lines: 341 to 348 

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

circumstances 

Comment: X. EPA is also requesting comments on whether aquifer exemptions should be 

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

such aquifer exemptions be approved. 

NYSDEC-DMN Response: Aquifer exemptions under Class VI should be allowed on the 

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

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

for future public water supply. 

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

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

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

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

17
expansions of existing Class II EOR/EGR aquifer exemptions for GS projects must meet all of 

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

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

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

EOR/EGR wells to Class VI. 

All decisions regarding whether expansion of existing aquifer exemptions will be at the 

Director's discretion and based on site-specific information. If an owner or operator applies for a 

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

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

depth requirements pursuant to §146.95 to ensure that if a waiver is granted, USDWs above and 

below the injection zone are protected from endangerment. 

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

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

Request for Comment. 

Letter ID: 0186 Comment ID: 25197 Letter Lines: 352 to 358 

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

Comment: Y. Finally, EPA seeks comment on whether the Agency should set a minimum 

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

take place below the lowermost USDW. 

NYSDEC-DMN Response: It is NYSDEC-DMN’s opinion that the EPA should not set a 

minimum injection depth requirement for CO2 GS operations. The decision to 

permit a project should be made on a site- specific basis and evaluation. 

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

GS projects. EPA believes that a determination of site-suitability for GS (i.e., that subsurface 

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

GS rule, at §146.82, requires the owner or operator to provide extensive site- and project-specific 

information to the Director to demonstrate that the site meets the minimum site criteria at 

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

protected from endangerment. 

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

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

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

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

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

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

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

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

18
owner or operator, the Director, and the Regional Administrator consider, on a site specific basis, 

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

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

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

Request for Comment. 

Letter ID: 0186 Comment ID: 25198 Letter Lines: 362 to 369 

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

(seeking comment) 

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

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

USDWs. 

NYSDEC-DMN Response: Use of tracers in CO2 GS operations should not be routinely 

required although such should be an optional methodology for use at Director 

discretion. The shortcomings of routine use of tracers for GS operations were 

discussed at length at the February 2008 EPA stakeholder workshop. 

Individual Response: EPA agrees that tracer use is not appropriate in all situations. 

Nevertheless, there are many different types of tracers and not all are problematic; research is 

being done to overcome problems with existing tracers. EPA believes that tracers have been used 

safely and successfully in other applications. For this reason, EPA does not require the use of 

tracers at all GS sites. Rather, the Director has discretion to require their use if he/she determines 

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

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

approved by the Director. 

EPA has been following new and ongoing research on the safety and efficacy of tracers, and 

believes that, in some circumstances, tracers can be an effective part of monitoring GS projects. 

EPA will continue to track research related to tracer use and plans to, every six years, collect and 

review data on GS projects to determine whether the appropriate amount and types of 

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

modifications to the requirements are appropriate or necessary. 

Letter ID: 0186 Comment ID: 25199 Letter Lines: 371 to 380 

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

Comment Code: 4520 2.5.1 Continuous internal mechanical integrity monitoring (seeking 

comment) 

Comment: III A. 5 Proposed Mechanical Integrity Testing Requirements 

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

19
NYSDEC-DMN Response: NYSDEC-DMN supports EPA’s proposal to require operators of 

GS projects to monitor internal mechanical integrity by continuously monitoring 

injection pressure, flow rate, and injected volumes, as well as annular pressure 

and fluid volume to provide early detection of anomalies that may indicate an 

internal leak. However, an "alarm" should shut in the well at the surface rather 

than requiring the installation and use of a downhole shut-off valve. 

Individual Response: EPA acknowledges the comment and believes that continuous pressure 

monitoring to demonstrate internal mechanical integrity of Class VI wells required at §146.89(b), 

instead of periodic testing, which is required for most other types of deep injection wells is 

important given the potential corrosive impact of CO2 and impurities on well materials, the 

potential geomechanical impacts to well integrity due to CO2 phase changes, and the 

temperature and pressure effects associated with injecting supercritical CO2. For additional 

information, please see the discussion of MITs in the final rule preamble. 

To meet the requirements at §146.88(e), Class VI wells will be equipped with some type of 

continuous computer-based monitoring device that will be connected to alarms and the shut-off 

system. EPA does not believe it is necessary to specify what type of equipment is to be used to 

trigger the shut-off system. Instead, the regulation allows the owner or operator some flexibility 

in deciding what equipment and alarms should be installed to allow site specific flexibility and to 

make use of improvements in technology. The technology for continuous monitoring is available 

and is currently in fairly wide use. The combination of computer-driven continuous pressure 

monitoring linked to an automatic injection shut-off provides maximum protection of USDWs 

from endangerment and provides the earliest warning to owners or operators that well repairs 

need to be performed. 

Letter ID: 0186 Comment ID: 25200 Letter Lines: 384 to 392 

Comment Code: 4520 2.5.1 Continuous internal mechanical integrity monitoring (seeking 

comment) 

Comment Code: 4546 2.5.2.2 MIT frequency (seeking comment) 

Comment: BB. EPA seeks comment on the appropriate frequency of internal and external MITs 

for GS injection wells, the appropriate types of MITs, and how to optimize MIT 

methods for GS. 

NYSDEC-DMN Response: As stated above, NYSDEC-DMN supports continuous monitoring 

of internal mechanical integrity for GS injection wells. For external MITs, the 

frequency should be more or less annually depending upon the specific 

circumstances. The types of tests allowed should be those appropriate under the 

specific circumstances. 

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

internal mechanical integrity (MI). The final GS rule retains the requirement for continuous 

pressure monitoring of Class VI wells to demonstrate internal mechanical integrity and annual 

20
external MITs. 

EPA believes that the annual external mechanical integrity testing is appropriate for GS wells. 

EPA retains the requirement that owners or operators of Class VI wells demonstrate injection 

well external mechanical integrity at least once annually. See §146.89(c). EPA believes this is 

justifiable for the protection of USDWs from endangerment given the unique nature of CO2 GS 

relative to other injection operations, including the potential corrosive impact of CO2 in the 

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

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

injecting supercritical CO2, and the buoyant nature of the injected CO2. Because of the unknown 

long-term effects of CO2 GS, EPA chose a more conservative initial approach in the early stages 

of deployment for GS. 

EPA believes that the MITs described in the rule at 146.89 are effective methods and have been 

used successfully by injection well operators for decades and provide an important early warning 

of potential problems in the injection well system. 

EPA clarifies that the regulations at §148.89(e) allow the Director to require additional methods 

or, with the Administrator's approval, to approve the use of alternative MIT methods based on 

specific information about the site or the well. For additional information, please see the 

discussion of MITs in the final rule preamble. 

Letter ID: 0186 Comment ID: 25201 Letter Lines: 396 to 404 

Comment Code: 4650 2.6.5 CO2 plume and pressure front tracking (seeking comment) 

Comment: CC. EPA seeks comment on the requirement for monitoring of GS sites for the 

purpose of tracking the location of the CO2 plume and associated pressure front 

over time. 

NYSDEC-DMN Response: NYSDEC-DMN is in favor of the EPA requiring an operator to 

conduct ongoing and sufficient monitoring to allow the tracking the CO2 plume 

and associated pressure front. In addition to any regular reporting frequency, 

an operator should be required to provide notification whenever actual 

conditions vary significantly from modeled predictions. 

Individual Response: EPA agrees with commenters on the importance of monitoring at GS sites 

and emphasizes that monitoring of injection activities will be an important component of every 

GS project. Monitoring associated with injection wells and the movement of the CO2 plume is 

necessary to verify that the injectate is confined in the target formations and does not endanger 

USDWs. 

EPA notes that the results of monitoring to track the plume and pressure front are to be 

incorporated into the reevaluation of the AoR, which must be conducted at least once every 5 

years under §146.84(e). EPA expects the monitoring results to be used to refine the AoR model. 

21
Letter ID: 0186 Comment ID: 25202 Letter Lines: 408 to 414 

Comment Code: 4640 2.6.4 Pressure fall-off testing (seeking comment) 

Comment: DD. EPA seeks comment on the use and frequency of pressure fall-off testing for 

GS wells. 

NYSDEC-DMN Response: NYSDEC-DMN is unclear as to the actual utility of pressure 

fall-off testing for operational GS wells. Instead of being mandated at least 

once every five years, the Director should have the discretion to require such 

testing as deemed appropriate. 

Individual Response: EPA believes that pressure fall-off testing is necessary for GS wells. 

Pressure fall-off tests are designed to verify that modeled projections of reservoir pressure 

decline agree with measured pressure decline profiles. These tests can be useful in AoR 

calculations and reevaluations and may also indicate mischaracterization of site geology and the 

presence of leakage pathways. EPA therefore believes that pressure fall-off testing must be 

conducted at least once every five years and the final GS regulation includes this requirement at 

§146.90(f). Pressure fall-off tests may be conducted in conjunction with other well performance 

tests (i.e., mechanical integrity testing) to ensure safe and effective operations. 

EPA believes that a frequency of at least once every five years, as specified at §146.90(f), is an 

appropriate interval for pressure fall-off testing (particularly given the suite of tests operators 

will perform on the well and the site). EPA clarifies that the Director may require more frequent 

pressure fall-off tests at a specific project, if necessary based on site-specific circumstances. 

Pressure fall-off tests may be conducted in conjunction with other well performance tests (i.e., 

mechanical integrity testing) to ensure safe and effective operations. All monitoring data 

collected, including information from pressure fall-off tests, will be incorporated in AoR 

reevaluations conducted at least every five years. 

Letter ID: 0186 Comment ID: 25203 Letter Lines: 418 to 431 

Comment Code: 4655 2.6.5.1 Plume tracking techniques/geophysical methods (seeking 

comment) 

Comment: EE. Based on information evaluated to date, EPA believes that tracking the plume 

and pressure front is an important companion step to address any uncertainties 

associated with initial AoR modeling and requests comment on this approach and 

more efficient alternatives that may be used to track the plume and pressure 

front. 

NYSDEC-DMN Response: NYSDEC-DMN agrees that tracking of the CO2 plume and 

pressure front is important and should be required. However, the exact 

methodology should not be specified but determined on a site-specific basis. 

NYSDEC-DMN also agrees with EPA’s statement "As such, allowing flexibility in 

22
choosing the plume tracking methods and other monitoring technologies may 

provide an appropriate balance between the protective nature of indirect 

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

continuously advancing technology." 

Individual Response: EPA agrees with commenters that an effective monitoring plan will need 

to consider site-specific conditions. The final rule (at §146.90(g)) requires owners or operators to 

perform monitoring to track the extent of the CO2 plume and pressure front. The owner or 

operator must use direct methods to monitor for pressure changes in the injection zone. Indirect 

methods (e.g., seismic, electrical, gravity, or electromagnetic surveys and/or down-hole CO2 

detection tools) are required unless the Director determines, based on site-specific geology that 

such methods are not appropriate. 

EPA believes that this approach provides flexibility to develop a site-specific monitoring plan, 

ensures that direct monitoring is available to track movement of the CO2 and validate models, 

and recognizes that indirect techniques are not appropriate in all situations. The owner or 

operator's approved testing and monitoring plan will include the site-specific details, 

technologies, testing and monitoring frequencies, and other pertinent information. 

EPA believes that pressure monitoring in the injection zone is necessary to track the 

development and movement of the pressure front and CO2 plume, and, for this reason, all GS 

well owners or operators must use direct methods to monitor for pressure changes in the 

injection zone, as required at §146.90(g)(1). 

EPA is affording Director's discretion regarding the use of geophysical techniques at some sites 

because the Agency recognizes that geophysical methods are not appropriate in all geologic 

settings. For example, geophysical methods are difficult to execute in areas that are structurally 

and topographically complex or where lithologies have limited contrast in density, porosity, 

permeability, and other physical properties. EPA clarifies that this determination will be made by 

the Director based on the site-specific geologic information submitted by the owner or operator 

with the permit application. 

Letter ID: 0186 Comment ID: 25204 Letter Lines: 435 to 443 

Comment Code: 4600 2.6 Proposed Plume and Pressure Front Monitoring Requirements (40 

CFR 146.90) 

Comment Code: 4760 2.7.6 Proposed reporting frequency (seeking comment) 

Comment: FF. EPA seeks comment on the appropriate amount and types of monitoring that 

should 

be conducted at a GS site. 

NYSDEC-DMN Response: NYSDEC-DMN agrees with EPA’s proposal to require operators 

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

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

results of MITs, ground water monitoring, and any required atmospheric/soil gas 

23
monitoring. However, the amount and types of monitoring to be required should be 

site specific. 

Individual Response: EPA agrees that monitoring plans and methods need to be site-specific 

and believes that the monitoring requirements for GS sites at §146.90 provide an appropriate 

level of flexibility in structuring a testing and monitoring plan that protects USDWs from 

endangerment. 

The final regulation provides for flexibility in: 1) methodologies used to collect these data, 2) the 

spatial resolution at which the data should be collected, and 3) how often the data should be 

collected. The number and placement of monitoring wells will be based on site-specific 

information such as the calculated AoR, injection rate and volume, site geology, baseline data, 

and the presence of artificial penetrations within the AoR. In some instances, there may be a 

limited number of options for complying with EPA's minimum requirements. For example, 

monitoring for geochemical changes will require use of monitoring wells and collection of 

groundwater samples for chemical analysis. Many options currently exist for complying with 

other requirements, such as tracking the position of the plume and pressure front within the 

injection zone. 

Flexibility is also provided regarding how to monitor for the specific data required by the final 

rule. The testing and monitoring plan is developed by the owner or operator in consultation with 

the Director and is designed to ensure that a detailed, Director-approved document describing 

how monitoring will be conducted during the lifetime of the project exists. EPA is developing 

guidance on testing and monitoring to assist owners or operators and Directors in evaluating 

requirements under §146.90, including proposed monitoring plans. The guidance describes 

available technologies and recommended approaches for implementing a testing and monitoring 

plan, including pre-operational geophysical logging and testing of injection wells, MITs, 

injection well testing during operation, groundwater quality monitoring, tracking the CO2 plume 

and pressure front, and soil gas and surface air monitoring which may be required by the UIC 

Director for specific GS projects. 

EPA is retaining the semi-annual reporting requirements as proposed at §146.91(a). These 

requirements ensure the Director has the information needed to take preventive action in a timely 

manner to protect USDWs from endangerment. EPA notes that operators who want to streamline 

their reporting schedules can negotiate with the permitting authority to establish a schedule that 

allows reporting on all wells in a GS project at the same time; however, data for each well must 

be reported separately and at least as frequently as required at §146.91. For additional 

information, please see the final rule and the preamble for a discussion of EPA's final approach 

to recordkeeping and reporting. 

EPA agrees that some monitoring types and frequencies (e.g., associated with ground water 

monitoring and plume tracking) will be site-specific. These activities must be established in the 

approved testing and monitoring plan, which will be incorporated as a condition of the Class VI 

permit. 

24
Letter ID: 0186 Comment ID: 25205 Letter Lines: 447 to 457 

Comment Code: 4655 2.6.5.1 Plume tracking techniques/geophysical methods (seeking 

comment) 

Comment Code: 4760 2.7.6 Proposed reporting frequency (seeking comment) 

Comment: GG. Specifically, EPA seeks comment regarding the usefulness of indirect 

geophysical monitoring and surface air and soil gas monitoring. 

NYSDEC-DMN Response: NYSDEC-DMN agrees with EPA’s proposal to require operators 

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

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

results of MITs, ground water monitoring, and any required atmospheric/soil gas 

monitoring. However, the amount and types of monitoring that are required should 

be site specific. Certain geophysical monitoring techniques that successfully 

monitor plume migration in the southern states may not have any monitoring 

capability in northern Paleozoic basins. 

Individual Response: EPA agrees with commenters and believes that flexibility is important in 

developing and implementing a monitoring plan that is appropriately tailored for a specific GS 

site. The purpose of the requirement at §146.90 to develop site-specific testing and monitoring 

plans is to ensure that the monitoring performed at a site is appropriate for site operational 

conditions and the geologic setting. EPA believes that this is the best approach for addressing 

potential risks at GS sites. These flexible provisions in the monitoring requirements for Class VI 

wells enable the owner or operator to tailor monitoring programs to the specific needs of each 

project in consultation with the Director. 

EPA clarifies that the final rule, at §146.90(g)(2), requires owners or operators to track the 

position of the CO2 plume using indirect methods (e.g., seismic, electrical, gravity, or 

electromagnetic surveys and/or down-hole CO2 detection tools), unless the Director determines 

based on site-specific geology, that such methods are not appropriate. EPA is affording 

Director's discretion regarding the use of geophysical techniques at some sites because the 

Agency recognizes that geophysical methods are not appropriate in all geologic settings. For 

example, geophysical methods are difficult to execute in areas that are structurally and 

topographically complex or where lithologies have limited contrast in density, porosity, 

permeability, and other physical properties. EPA clarifies that this determination will be made by 

the Director based on the site-specific geologic information submitted by the owner or operator 

with their permit application. 

EPA believes that this approach provides flexibility to develop a site-specific monitoring plan, 

ensures that direct monitoring is available to track the movement of the CO2 and validate 

models, and recognizes that indirect techniques are not appropriate in all situations. The owner or 

operator's approved testing and monitoring plan must include the site-specific details, 

technologies, testing and monitoring frequencies, and other pertinent information. 

As described above EPA is retaining the requirement at §146.91(a) for semi-annual reporting of 

25
monitoring and operational data. For additional information, please see the final rule and the 

preamble for a discussion of EPA's final approach to recordkeeping and reporting. 

Letter ID: 0186 Comment ID: 25206 Letter Lines: 461 to 465 

Comment Code: 4610 2.6.1 Testing and monitoring plan requirement (seeking comment) 

Comment: HH. In addition, EPA seeks comment regarding the use of a Director-approved 

monitoring plan for GS sites. 

NYSDEC-DMN Response: The Director should be given flexibility to approve sitespecific monitoring plans. 

Individual Response: EPA agrees with commenters that developing and following testing and 

monitoring plans and giving Directors flexibility to approve the plans based on site-specific 

criteria are important parts of assuring that a GS project is operating properly and is crucial for 

the early detection of potential endangerment to USDWs. 

The testing and monitoring plan is developed by the owner or operator in consultation with the 

Director and is designed to ensure that a detailed, Director-approved document describing how 

monitoring will be conducted during the lifetime of the project exists. The testing and monitoring 

plan must be approved by the Director. EPA is developing guidance on testing and monitoring to 

assist owners or operators and Directors in evaluating requirements under §146.90, including 

proposed monitoring plans. The guidance describes available technologies and recommended 

approaches for implementing a testing and monitoring plan, including pre-operational 

geophysical logging and testing of injection wells, MITs, injection well testing during operation, 

groundwater quality monitoring, tracking the CO2 plume and pressure front, and soil gas and 

surface air monitoring which may be required by the UIC Director for specific GS projects. The 

guidance can be found on EPA’s website at 

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

Letter ID: 0186 Comment ID: 25207 Letter Lines: 469 to 475 

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

comment) 

Comment: II. EPA seeks comment on the merits of requiring plans for monitoring, AoR, and 

post-injection site care as part of a permit application. 

NYSDEC-DMN Response: NYSDEC-DMN believes monitoring and testing plans, an AoR 

and corrective action plan, and a post-injection site care and site closure plan 

are integral components of any GS application, and should be required by the 

EPA. 

Individual Response: EPA agrees that incorporating the plans into the permit rather than 

26
establishing specific requirements for corrective action, monitoring, injection well plugging, and 

post-injection site care in the regulation provide the appropriate flexibility to address the variety 

of site-specific conditions that may be encountered at GS sites. 

EPA also believes that it is appropriate to require owners and operators to submit all plans, 

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

time of permit application. EPA believes that the Director needs a satisfactory level of assurance 

that the owner or operator has planned for these events before injection commences and that the 

owner or operator has ensured that appropriate financial resources are available to fund all 

required activities, as required at §146.85. The final rule retains requirements for submitting 

these plans with the permit application at §146.82(a). EPA anticipates that the requirement for 

this and other plans associated with GS projects will promote an ongoing dialogue between the 

owner or operator and the Director to ensure USDWs are protected from endangerment and the 

owner or operator is complying the Class VI permit. In addition, these plans will support a 

demonstration that owners and operators have adequate financial resources to meet well plugging 

and post-injection site care and site closure requirements. Please see the final rule and the 

discussion of the GS project plans in the preamble for additional information. 

Letter ID: 0186 Comment ID: 25208 Letter Lines: 479 to 482 

Comment Code: 4760 2.7.6 Proposed reporting frequency (seeking comment) 

Comment: JJ. EPA seeks comment on the frequency of all proposed reporting requirements. 

NYSDEC-DMN Response: NYSDEC-DMN supports all stated reporting frequencies and 

requirements. 

Individual Response: The final GS regulation retains the reporting requirements as outlined in 

the proposed rule and does not include a requirement for an annual report. For additional 

information, please see the final rule and the preamble for a discussion of EPA's final approach 

to recordkeeping and reporting. 

The semi-annual reporting required at §146.91(a) includes both operational data and data 

required as part of the testing and monitoring plan, satisfying many of the concerns expressed by 

commenters who supported the annual report. 

Letter ID: 0186 Comment ID: 25209 Letter Lines: 486 to 492 

Comment Code: 4740 2.7.4 Electronic reporting (seeking comment) 

Comment: KK. EPA seeks comment on the requirement for electronic reporting in today’s 

proposed rule. 

NYSDEC-DMN Response: NYSDEC-DMN agrees with electronic submittal in principle as 

long as there is sufficient flexibility to allow states to utilize existing or 

27
preferred state data processing systems or software. At this time, electronic 

reporting should be an option but not a requirement. 

Individual Response: EPA believes that electronic formatting is the most appropriate format for 

submitting Class VI project information to the Director, and based on comments received on the 

proposed rule, the majority of Class VI well owners or operators will have the capability to 

report electronically, and requires this at §146.91(e). 

Acknowledging that some States may have to develop electronic data systems to receive 

electronic information from the owner or operator, and that many States which already have 

electronic data systems will have to make changes to accommodate a new class of UIC well 

(Class VI), EPA believes that it is prudent to provide assistance by developing a central 

framework for the electronic system that will be used by States to gather and track owner or 

operator data. This will enable owners or operators to submit data without having to wait for a 

State to develop a system. It will also provide for standardized submissions across the country 

and enable States to focus State resources on reviewing and approving permit applications rather 

than building or upgrading separate, independent databases for GS information. 

EPA is developing guidance for states that describes the recordkeeping, reporting, and additional 

data management needs associated with GS activities and provides recommended guidelines on 

the types of data to be collected for tracking GS projects, reporting to EPA for compliance 

tracking, and transfer of data to EPA's GS data system. The recordkeeping and reporting 

guidance will be available on EPA's web site, at 

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

Letter ID: 0186 Comment ID: 25210 Letter Lines: 496 to 501 

Comment Code: 4750 2.7.5 Comments on the merit of annual reports (seeking comment) 

Comment: LL. Although EPA has not included a requirement for this report in today’s 

proposal, EPA seeks comment regarding the necessity for such an annual report. 

NYSDEC-DMN Response: NYSDEC-DMN agrees with the concept and sees the merits of 

requiring an annual report that provides a narrative analysis of GS operations 

in addition to requiring semi-annual reporting of data. 

Individual Response: The final GS regulation retains the reporting requirements as outlined in 

the proposed rule and does not include a requirement for an annual report. EPA believes that 

periodic reevaluation of the AoR, as required at §146.84(e), along with any revisions to the 

required plans that may be necessary based on the AoR reevaluation or other data collected 

during well operations, will promote an ongoing relationship between the permitting authority 

and the owner or operator. The final GS rule, at §§146.84(c), 146.90(j), and 146.94(d), requires 

owners or operators to review and update the AoR and corrective action plan, the testing and 

monitoring plan, and the emergency and remedial response plan throughout the life of the 

project. Owners or operators must review each plan and identify necessary amendments to the 

plan or demonstrate to the Director that no amendment is needed. These reviews must be 

28
performed within one year of an AoR reevaluation, following any significant changes to the 

facility (e.g., the addition of monitoring or injection wells), or when required by the Director. In 

no case can reviews occur less often than once every five years. For additional information, 

please see the final rule and the preamble for a discussion of EPA's final approach to 

recordkeeping and reporting. 

The semi-annual reporting required at §146.91(a) includes both operational data and data 

required as part of the testing and monitoring plan, satisfying many of the concerns expressed 

commenters who supported the annual report. 

Letter ID: 0186 Comment ID: 25211 Letter Lines: 503 to 518 

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

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

Requirements 

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

timeframe that could be modified at the Director’s discretion based on 

monitoring and modeling data. 

NYSDEC-DMN Response: Given that current injection and reservoir behavior data 

demonstrates a decreasing risk of leakage after injection ceases, NYSDEC-DMN 

believes that a 50-year default time frame for post-injection site care is too 

long and that a 30-year starting period may be more appropriate to allow GS 

projects to move forward. It would be better to prescribe a shorter period with 

discretion to go longer, rather than vice versa, as such would better facilitate 

project planning. Regardless, it is critical that the Director have the 

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

particular project. 

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 alternative timeframes may be 

appropriate under limited, specific circumstances. 

29
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. 

Letter ID: 0186 Comment ID: 25212 Letter Lines: 523 to 535 

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

Comment: NN. EPA is requesting comments on the proposed requirements for well plugging, 

post- injection site care, and site closure, including the proposed requirements 

for the post-injection time period. 

NYSDEC-DMN Response: Given that current injection and reservoir behavior data 

demonstrates a decreasing risk of leakage after injection ceases, NYSDEC-DMN 

believes that a 50-year default time frame for post-injection site care is too 

long and that a 30-year starting period may be more appropriate to allow GS 

projects to move forward. It would be better to prescribe a shorter period with 

discretion to go longer, rather than vice versa, as such would better facilitate 

project planning. Regardless, it is critical that the Director have the 

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

particular project. 

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 

30
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 alternative timeframes may be 

appropriate under limited, specific circumstances. 

For this reason, the GS rule offers owners or operators flexibility regarding the duration of the 

PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC 

timeframe during the post-injection period based on site-specific data, pursuant to requirements 

at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator 

to demonstrate, during the permitting process based on substantial data, that an alternative PISC 

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to 

requirements at §146.93(c). 

EPA believes 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. 

Letter ID: 0186 Comment ID: 25213 Letter Lines: 540 to 553 

Comment Code: 5260 2.8.2.3 Adjusting the post-injection timeframe (seeking comment) 

Comment: OO. In addition, EPA seeks comment on whether the Director should be allowed to 

shorten the timeframe based on performance information, and whether EPA should 

require a shorter or longer post-injection period if data suggests the time 

frame should be adjusted. 

31
NYSDEC-DMN Response: Given that current injection and reservoir behavior data 

demonstrates a decreasing risk of leakage after injection ceases, NYSDEC-DMN 

believes that a 50-year default time frame for post-injection site care is too 

long and that a 30-year starting period may be more appropriate to allow GS 

projects to move forward. It would be better to prescribe a shorter period with 

discretion to go longer, rather than vice versa, as such would better facilitate 

project planning. Regardless, it is critical that the Director have the 

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

particular project. 

Individual Response: EPA acknowledges 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 most cases. The 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. 

As described above, 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. While the 10- or 30-year timeframe suggested by some of these commenters may be 

within the timeframe suggested in some studies, there are circumstances (e.g., little development 

of mineral trapping of CO2) under which 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. 

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. 

Letter ID: 0186 Comment ID: 25214 Letter Lines: 557 to 574 

32
Comment Code: 5430 2.9.1 Comments on proposed financial responsibility requirements (40 

CFR 146.85) 

Comment: PP. EPA is requesting comments on whether financial responsibility mechanisms to 

be recommended in EPA guidance should be adjusted in the manner described, 

whether additional instruments should be included, and whether other adjustments 

to the financial responsibility mechanisms should be considered, all subject to 

EPA’s authority under the SDWA. 

NYSDEC-DMN Response: The EPA proposed rule for financial assurance appears to be 

adequate with respect to wells and NYSDEC-DMN understands that any well plugging 

financial instrument would be released upon proper plugging and abandonment of 

the well. It is also understood that a second tier of financial assurance, that 

could be filed at a later date (i.e., closer to ceasing injection), is being 

considered for post-injection site care. However, according to the proposed 

rule, both forms of financial assurance would be limited to SDWA authority which 

does not extend to financial responsibility for activities unrelated to 

protection of USDWs (e.g., coverage of risks to air, ecosystems, or public 

health unrelated to USDW endangerment). Because of EPA’s focused authority under 

the SDWA for the UIC program, action by individual states may be required to 

fill any financial assurance and regulatory gaps. 

Individual Response: EPA agrees that assuring financial responsibility for corrective action of 

Class VI wells in the AoR, injection well plugging, PISC and site closure, and emergency and 

remedial response at GS sites is an important component of ensuring that USDWs are protected. 

EPA clarifies that financial assurance for post-injection site care and site closure can be obtained 

separately from that for well plugging; however, financial responsibility for post-injection site 

care and site closure must be demonstrated at the time the permit application is filed. Please note 

that the rule requires the owner or operator to adjust the cost estimates of the financial instrument 

to address any amendments to the AoR and corrective action plan, the injection well plugging 

plan. Within 60 days after the Director has approved any modification to the plan(s), the owner 

or operator must review and update the cost estimate for well plugging, PISC and site closure, 

and emergency and remedial response to account for any amendments to the permit plans listed 

above. See the final rule and preamble for further discussion of EPA's final approach to financial 

responsibility. 

EPA confirms that its authority to require financial responsibility is limited to that allowed by the 

SDWA as part of the UIC program. Financial responsibility and liability for activities unrelated 

to the protection of USDWs is outside the scope of this rulemaking. 

Letter ID: 0186 Comment ID: 25215 Letter Lines: 578 to 598 

Comment Code: 5436 2.9.1.3 Allowing separate financial demonstrations for plugging and 

abandonment and post-injection site care (seeking comment) 

33
Comment: QQ.The Agency is also requesting comment on allowing separate financial 

demonstrations to be submitted for the plugging of the injection well and for 

the post-injection site care requirements. 

NYSDEC-DMN Response: EPA’s proposal for financial assurance appears to be 

adequate with respect to wells and NYSDEC-DMN understands that any well plugging 

financial instrument would be released upon proper plugging and abandonment of 

the well. It is also understood that a second tier of financial assurance, that 

could be filed at a later date (i.e., closer to ceasing injection), is being 

considered for post- injection site care. EPA states that it is considering 

requiring well plugging financial demonstration at permit issuance and postinjection site care financial security demonstration at a later time (e.g., 

within 180 days of notifying the Director that the well will be plugged and 

abandoned). EPA also states "Trying to determine the cost for post-injection 

site care, possibly 30 to 50 years in the future, could be difficult, as could 

the approval of a financial demonstration." It is NYSDEC-DMN’s opinion that some 

level of financial assurance for post-site injection care should be in place at 

first injection of CO2. If there are concerns with uncertainty and overly 

burdening an operator, perhaps the amount of post-injection site care assurance 

could start with a basic level of protection and be required to be increased as 

the potentially affected area grows over time with additional injection. 

Individual Response: EPA agrees that an initial financial responsibility demonstration at the 

time of permitting is appropriate. In the final rule, owners or operators are required to 

demonstrate, with their permit applications, adequate financial responsibility for all GS activities 

that require financial responsibility, at §146.82(a)(14). This will ensure that resources are 

available to prevent the endangerment of USDWs in the event that the owner or operator 

experiences financial difficulties at any time during the life of the GS project. 

The final GS rule, at §146.85(c), also requires the owner or operator to provide annual updates to 

the cost estimate to account for any amendments to the AoR and corrective action plan, the 

injection well plugging plan, the PISC and site closure plan, and the emergency and remedial 

response plan. Owners or operators must also adjust the estimates for inflation annually under 

§146.85(c)(2). EPA adds that the Director can also require the owner or operator to provide an 

adjustment of the cost estimate if the Director determines that the original demonstration is no 

longer adequate, as specified at §146.85(e). 

In order to assist owners or operators and financial institutions in achieving accurate cost 

estimates for all GS activities, EPA plans to issue financial responsibility guidance that will 

include a discussion of how best to estimate costs, including how to adjust cost estimates for 

inflation to account for the long-term nature of GS projects, in its guidance on meeting financial 

responsibility requirements for GS wells. This guidance will be available on EPA's website at 

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

Letter ID: 0186 Comment ID: 25216 Letter Lines: 603 to 613 

34
Comment Code: 5520 2.10.1 Appropriateness of existing public participation requirements 

(Part 25 and Part 124) for GS (seeking comment) 

Comment: RR. EPA requests comment on adopting the existing requirements for public 

participation at 40 CFR Part 25 and 40 CFR Part 124 and whether additional 

requirements should be included to reflect the availability of new tools for 

disseminating and gathering information. Such tools include cable networks, the 

Internet, and other new technology. 

NYSDEC-DMN Response: All states have public notice laws and regulations that 

cover most regulatory and permitting functions. These laws and regulations would 

extend to the permitting and the regulation of GS that require public notice, 

hearings and due process to all affected parties. This should be adequate for 

public involvement purposes. 

Individual Response: EPA does not require the use of any new information technologies to 

inform the public, but encourages GS project operators and permitting authorities to use the 

Internet as well as both new and established tools to explain and post information on the latest 

developments. This information may include schedules for hearings, briefings, and other 

opportunities for involvement. EPA plans to conduct outreach on the GS rule, and provides GS 

related information on its website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. EPA currently uses social 

networking applications for important information (e.g., Facebook and Twitter), and will 

encourage GS operators and permitting authorities to use similar technologies to keep the public 

informed of GS projects. If states have applicable public participation requirements, these would 

need to be met as well. 

EPA believes that the existing UIC public participation requirements as specified in 40 CFR 25 

and 40 CFR 124 are appropriate for GS projects. In addition, because of the unique nature of GS 

projects, and the anticipated level of public interest in GS projects, EPA encourages early public 

involvement in GS projects. Providing the public with accurate, project specific information in 

the early stages of each GS project can help clarify project details and avoid public 

misperceptions about the nature and safety of GS projects, and will allow a potential GS owner 

or operator and the permitting agency to address the public's concerns before the permitting 

process is complete. 

EPA understands that public notice laws and regulations vary from state to state. EPA would like 

to clarify that in order for a state to receive primacy for Class VI GS wells their public notice 

requirements for permits must be at least as stringent as those required under Part 124. This 

requirement should provide a level uniformity between primacy states for purposes of providing 

public notice for GS wells. 

Letter ID: 0186 Comment ID: 25217 Letter Lines: 618 to 624 

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

35
Comment: SS. EPA is seeking comment on the merits and possible disadvantages of allowing 

primacy approval for Class VI wells independent of other well classes. 

NYSDEC- DMN Response: NYSDEC-DMN supports the creation of a separate class VI 

for GS wells and strongly supports allowing state primacy solely for Class VI. 

In addition, states should have the authority to designate which agency in the 

state can apply for and be granted primacy. 

Individual Response: As described above, EPA agrees with commenters that states should be 

allowed to obtain primacy for Class VI wells independently of other well classes, and will allow 

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

EPA also clarifies that primacy is granted to a state, not to any agency within that state, and 

states are free to choose which agency will implement the Class VI program—for instance, an 

environmental quality protection agency (non-Class II) or the state's traditional oil and gas 

regulatory agency (Class II)—as long as the program meets the minimum Federal requirements 

for Class VI wells as required under section 1422 of SDWA. Some states administer their 

program for all injection well classes through a single agency, whereas other States elect to 

divide the program between agencies. For example, in most States, the Class II program is run by 

an oil and gas agency and other well classes are run by a State environmental agency (e.g., the 

Oklahoma Corporation Commission oversees Class II wells in the State, and the Oklahoma 

Department of Environmental Quality oversees other well classes). Additionally, several States 

allow their oil and gas agencies to administer their UIC program for specific well classes or 

subclasses provided they meet all Federal requirements (e.g., the Texas Railroad Commission 

oversees Class III brine-mining wells and Class V geothermal wells in Texas). EPA believes that 

retaining this flexibility for States to identify the appropriate agency to oversee Class VI wells 

will address commenters’ concerns that States should be afforded the opportunity to determine 

which agency should oversee Class VI wells, and recognizes the existing expertise of both State 

oil and gas agencies and environmental agencies. 

Letter ID: 0186 Comment ID: 25218 Letter Lines: 628 to 632 

Comment Code: 5700 2.12 Comments on the proposed duration of Class VI permits (seeking 

comment) 

Comment: TT. Therefore, EPA proposes that Class VI injection well permits would be issued 

for the operating life of the GS project including the post-injection site care 

period. EPA seeks comment on the merits of this approach. 

NYSDEC-DMN Response: NYSDEC-DMN agrees with the EPA proposal. 

Individual Response: EPA agrees with commenters. The final rule maintains the lifetime permit 

provision and clarifies that the permit extends through the post-injection site care period 

(144.36(a)). However, it also adds a requirement that the Director review each Class VI permit at 

36
37

least every 5 years to determine whether it should be modified, revoked and reissued, terminated 

or a minor modification made as provided in §§144.39, 144.40, or 144.41. The Director’s review 

will be informed by the owners’ or operators’ iterative reevaluation of the project. Specifically, 

the final rule includes a requirement that the AoR be reevaluated at least every five years, and 

also requires owners or operators to review and update the AoR and corrective action plan, the 

testing and monitoring plan, and the emergency and remedial response plan throughout the life 

of the project (146.84(e), 146.90(j), and 146.94(d)). Owners or operators must review each plan 

and identify necessary amendments or demonstrate to the Director that no amendment is needed. 

In no case can reviews occur less often than once every five years. The iterative process and 

subsequent plan reevaluations ensure that time and resources are committed to the most critical 

aspects of the permit in preventing endangerment to USDWs. 

EPA believes that the iterative process of developing and executing the various plans required of 

GS well operators in the final rule (e.g., for AoR and corrective action, testing and monitoring, 

well plugging, and post-injection site care, and emergency and remedial response) is tailored to 

the unique aspects of—and is more appropriate for–GS than establishing a finite permit duration 

(e.g., five years as suggested by some commenters).