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.
EPA-HQ-OW-2008-0390-0153

Document ID: EPA-HQ-OW-2008-0390-0153

Last Name: Pirner

First Name: Steven

Title: Secretary

Organization: South Dakota Department of Environment and Natural Resources

City: Pierre

State: SD

Zip Code: 57501

Phone Number: 6057733151

Fax Number: 6057736035

Country Code: 

Email Address: 

Current Category Code: 250

Comment: 

Docket ID: EPA-HQ-OW-2008-0390

Docket Title: Underground Injection Control (UIC) Program: Federal Requirements

for Class VI Injection Wells for the Geologic Sequestration of Carbon Dioxide -

Proposed Rule

Listed below are comments from the South Dakota Departmment of Environment and

Natural Resources regarding the proposed EPA rules establishing a new class of

underground injection wells pertaining to the deep well geologic sequestration

of carbon dioxide. Part I are more general comments, while Part II consists of

more regulation specific comments.

We appreciate the chance to comment on the rules. In general we believe EPA has

done a good job in formulating rules that will be protective of underground

sources of drinking water (USDW) without being overly stringent on operators,

given the potential size, scope and impact of the sequestration operations. Our

main concerns focus on states being given sufficient flexibility to regulate

such a program efficiently and effectively.

Sincerely,

Steven M. Pirner

Secretary

South Dakota Department of Environment and Natural Resources

Part I:

1. South Dakota recommends that more flexibility be given to the type and

location of formations where CO2 can be sequestered. At this point EPA is

proposing to only allow sequestration in formations below the lowermost USDW (as

noted in 144.6 (f), and 146.5 (f)). In South Dakota there are strata that could

potentially be used for sequestration that are above the lowermost USDW and have

significant confining beds. The eastern portion of the state is generally

unsuitable for sequestration as the Precambrian basement rock is less than 3000

feet deep in most places, is used as a USDW in some areas, and an additional

USDW directly overlies it in some cases.

2. To allow for additional flexibility, South Dakota recommends that aquifer

exemptions be allowed for Class VI wells.

3. We would also recommend that a minimum injection depth for CO2 sequestration

not be required, again to allow states more flexibility in determining areas

where the process can occur. We believe the initial site evaluation, testing,

modeling and so forth required of the owner/operators of a geologic

sequestration site along with all operational testing would maintain protection

of a USDW without requiring a prescriptive depth limitation.

4. South Dakota recommends that EPA allow states to gain regulatory primacy of

Page 1
EPA-HQ-OW-2008-0390-0153

UIC Class VI wells without having to also take primacy for the other UIC classes

in Section 1422 of the SDWA. Class VI wells actually appear more closely related

to UIC Class II wells in Section 1425 of the SDWA than those in Section 1422.

5. There was no appreciable discussion of funding mechanisms to run the program

at the state level.

Part II:

144.18 Requirements of Class VI wells - owners must get a permit versus ruleauthorization - much more detailed application, and has/allows for public input.

We are in agreement with this.

146.81 Applicability (c) - exempts Class I, II, and V wells from having to do

cement work-overs if wells protective of USDWs - this is good use of these other

wells once their original use is completed

(d) - Definitions - Area of review - as defined, is equivalent of Class II Radii

of Influence - since this is calculated instead of established as a fixed radius

as set by a lot of states' regulations, this will relieve a lot of confusion,

especially for the use of horizontal wells

- Geologic sequestration - subsurface emplacement of CO2 - good specification in

definition as some more local organizations refer to "carbon sequestration" as

also putting CO2 in wetlands and/or planting trees in surface. If states have to

establish their own regulations, this definition could help differentiate the

surficial aspect from subsurface sequestration

146.82 Required Class VI permit information - (e) ".... and any additional

information the Director may require:" - this is good part, as we as a state

have had numerous occasions when operators do not submit all of the information

needed to determine the viability of an application for a well because it is not

specifically listed in the state regulations

146.84 Area of review and corrective action - (b) (2) (i) the need to reevaluate the area of review a maximum of every 10 years - great clause, we have

potential for problems in our Class II program where operators could potentially

over inject, especially if the life of permit expires

146.85 Financial responsibility - (b) need to re-evaluate AOR, CAP, P&A, and

post-injection site care and closure plans and the financial resources needed to

address them on a frequency set by Director - this prevents the initial

determination of bonding from becoming inadequate in future - our Class II

regulations set a specific amount that can not be changed over time, and allow

for a group of wells to be covered under the same, inadequate statewide bonding

mechanism

146.86 Injection well construction requirements - (a) (2) well must be

constructed such to allow appropriate testing devices and work-over tools - this

is a good clause also, as our Class II regulations have allowed for a

temporarily abandoned well that was worked over in such a way so it will be

difficult to MIT it - may have to bring in an expensive R(adio)A(ctive)T(racer

log) test rig - we couldn't prevent it under our Class II regulations

(b) (2) extending surface casing through the base of the lower-most USDW - this

may be over kill in areas where there are multiple aquifers at numerous

different depths. Especially in areas where the upper USDWs easily fulfill the

needs of the populace, and the deeper USDWs are of high TDS content, and may

take considerable, expensive treatment to bring it to palatable levels. In

addition, this would be more overkill if both the tubing and long string

injection casings are cemented from bottom to surface.

(b) (3) at least one long string must extend to the injection zone and be

Page 2
EPA-HQ-OW-2008-0390-0153

cemented to the surface - same as comment for (b) (2) previous - especially if

tubing is cemented from top to bottom, and long string is cemented into surface

casing.

146.88 Injection well requirements - (c) the annulus pressure needs to exceed

the injection pressure - don't know why, as long as there is enough difference

so sensors/gauges can indicate when something goes wrong.

Page 3
Letter ID: 0153 

Commenter: Steven Pirner 

Organization: South Dakota Department of Environment and Natural Resources 

Letter ID: 0153 Comment ID: 22133 Letter Lines: 28 to 31 

Comment Code: 1420 1.2.1.1 Support the GS rulemaking 

Comment: We appreciate the chance to comment on the rules. In general we believe EPA has 

done a good job in formulating rules that will be protective of underground 

sources of drinking water (USDW) without being overly stringent on operators, 

given the potential size, scope and impact of the sequestration operations. Our 

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

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

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

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

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

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

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

captured CO2, and its mobility within subsurface geologic formations. 

Letter ID: 0153 Comment ID: 22134 Letter Lines: 31 to 33 

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

Comment Code: 1530 1.2.3.1 State regulatory efforts on GS (seeking comment) 

Comment: given the potential size, scope and impact of the sequestration operations. Our 

main concerns focus on states being given sufficient flexibility to regulate 

such a program efficiently and effectively. 

Individual Response: EPA clarifies that SDWA, under section 1422(b)(3)(9)(A), requires that 

the regulations of the Administrator "permit or provide for varying geologic, hydrological, or 

historical conditions in different states and in different areas within a state." In the final GS rule, 

EPA has provided the Director discretion in applying the GS requirements, taking into account 

varying conditions, particularly with regard to the evaluation of site characteristics. 

For additional information, please see the discussion of EPA’s Final Regulatory Approach in the 

preamble to the final GS rule and the section entitled, “How Does This Action Affect UIC 

Program Implementation?" 

Letter ID: 0153 Comment ID: 22135 Letter Lines: 43 to 44 

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

1
Comment: 1. South Dakota recommends that more flexibility be given to the type and 

location of formations where CO2 can be sequestered. At this point EPA is 

Individual Response: EPA agrees that permitting decisions for GS wells should be based on 

site-specific factors. The GS rule requires owners or operators to submit, and Directors to 

consider, extensive site-specific data, specified at §146.82, to demonstrate that a site is suitable 

for GS. Additionally, many of the permit requirements for GS wells are established through 

individualized site-specific plans for AoR and corrective action, testing and monitoring, and 

injection well plugging and post-injection site care and site closure. EPA adds that the final GS 

rule includes a balance of specific criteria to be met by the owner or operator and areas of 

Directorial discretion and considerations for how that discretion would be exercised. The Agency 

believes this balance allows for GS projects to be designed and permitted to address the unique, 

site-specific aspects of each project, while providing consistency in permitting across the U.S. 

Letter ID: 0153 Comment ID: 22136 Letter Lines: 44 to 51 

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

USDW 

Comment: location of formations where CO2 can be sequestered. At this point EPA is 

proposing to only allow sequestration in formations below the lowermost USDW (as 

noted in 144.6 (f), and 146.5 (f)). In South Dakota there are strata that could 

potentially be used for sequestration that are above the lowermost USDW and have 

significant confining beds. The eastern portion of the state is generally 

unsuitable for sequestration as the Precambrian basement rock is less than 3000 

feet deep in most places, is used as a USDW in some areas, and an additional 

USDW directly overlies it in some cases. 

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. 

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

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

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

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

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

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

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

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

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

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

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

2
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: 0153 Comment ID: 22137 Letter Lines: 53 to 54 

Comment Code: 4450 2.4.4.4 Use of aquifer exemptions (seeking comment) 

Comment: 2. To allow for additional flexibility, South Dakota recommends that aquifer 

exemptions be allowed for Class VI wells. 

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

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

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

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

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

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

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: 0153 Comment ID: 22138 Letter Lines: 56 to 61 

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

Comment: 3. We would also recommend that a minimum injection depth for CO2 sequestration 

not be required, again to allow states more flexibility in determining areas 

where the process can occur. We believe the initial site evaluation, testing, 

modeling and so forth required of the owner/operators of a geologic 

sequestration site along with all operational testing would maintain protection 

of a USDW without requiring a prescriptive depth limitation. 

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

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

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

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

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

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

USDWs will be protected from endangerment. 

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

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

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

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

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

3
extensive, site-specific information (in conjunction with the permit application submission) to 

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

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

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

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

availability and USDW protection. For additional information on the waiver approach, please see 

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

Availability and Request for Comment. 

Letter ID: 0153 Comment ID: 22139 Letter Lines: 63 to 66 

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

Comment: 4. South Dakota recommends that EPA allow states to gain regulatory primacy of 

UIC Class VI wells without having to also take primacy for the other UIC classes 

in Section 1422 of the SDWA. Class VI wells actually appear more closely related 

to UIC Class II wells in Section 1425 of the SDWA than those in Section 1422. 

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

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

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

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

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

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

management of CCS. EPA believes that allowing independent Class VI primacy may encourage 

states to take responsibility for implementation of Class VI regulations and provide for a more 

comprehensive approach to managing CCS projects by promoting the integration of GS activities 

under SDWA into a broader framework for managing CCS. Furthermore, GS operations involve 

ancillary activities (e.g., pipeline operations, pore space ownership, land use rights, and surface 

access) for which states can call upon other authorities that exist at the state level (but outside 

UIC authority) to provide a more comprehensive CCS management approach. 

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 

4
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: 0153 Comment ID: 22140 Letter Lines: 68 to 69 

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

Comment: 5. There was no appreciable discussion of funding mechanisms to run the program 

at the state level. 

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: 0153 Comment ID: 22141 Letter Lines: 73 to 75 

Comment Code: 3150 2.1.5 Comments on required permit information (40 CFR 146.82) 

Comment: 144.18 Requirements of Class VI wells - owners must get a permit versus ruleauthorization - much more detailed application, and has/allows for public input. 

We are in agreement with this. 

Individual Response: EPA acknowledges the comment and the final rule retains the 

requirement as proposed. 

Letter ID: 0153 Comment ID: 22142 Letter Lines: 77 to 79 

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

Comment: 146.81 Applicability (c) - exempts Class I, II, and V wells from having to do 

cement work-overs if wells protective of USDWs - this is good use of these other 

5
wells once their original use is completed 

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

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

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

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

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

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

The requirements of the GS rule apply once the project initiates long-term sequestration of CO2. 

Letter ID: 0153 Comment ID: 22143 Letter Lines: 81 to 90 

Comment Code: 1220 1.1.1.1 Terminology and definitions 

Comment: (d) - Definitions - Area of review - as defined, is equivalent of Class II Radii 

of Influence - since this is calculated instead of established as a fixed radius 

as set by a lot of states' regulations, this will relieve a lot of confusion, 

especially for the use of horizontal wells 

- Geologic sequestration - subsurface emplacement of CO2 - good specification in 

definition as some more local organizations refer to "carbon sequestration" as 

also putting CO2 in wetlands and/or planting trees in surface. If states have to 

establish their own regulations, this definition could help differentiate the 

surficial aspect from subsurface sequestration 

Individual Response: EPA believes that the use of computational modeling required at 

§146.84(c)(1), rather than relying on a fixed radius or simple computation, is necessary to 

account for the complexity of GS projects. EPA believes that predicting the complex multiphase, 

buoyant flow of the CO2, co-injectates, and compounds that may be mobilized due to injection 

requires the sophistication of computational models. Models can predict CO2 fate and transport, 

as well as changes in formation pressure, in three dimensions, as a function of time in order to 

delineate the subsurface storage site and the AoR. Models can account for site-specific and 

predicted operating conditions as well as geologic heterogeneities and potential migration 

through faults, fractures, and artificial penetrations. 

The Agency has carefully considered all comments on the AoR definition at §146.84(a) and 

modified it to read as follows: “[T]he region surrounding the geologic sequestration project 

where USDWs may be endangered by the injection activity. The area of review is delineated 

using computational modeling that accounts for the physical and chemical properties of all 

phases of the injected CO2 stream and is based on available site characterization, monitoring, 

and operational data.” 

The Agency has modified the definition of geologic sequestration project at §146.81(d) to read 

as follows: “[A]n injection well or wells used to emplace a carbon dioxide stream beneath the 

6
lowermost formation containing a USDW; or, wells used for geologic sequestration of carbon 

dioxide that have been granted a waiver of the injection depth requirements pursuant to 

requirements at § 146.95; or, wells used for geologic sequestration of carbon dioxide that have 

received an aquifer exemption expansion. It includes the subsurface three-dimensional extent of 

the carbon dioxide plume, associated pressure front, and displaced brine, as well as the surface 

area above that delineated region.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA 

and Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the 

final rule and preamble for additional information. 

Letter ID: 0153 Comment ID: 22144 Letter Lines: 92 to 96 

Comment Code: 3150 2.1.5 Comments on required permit information (40 CFR 146.82) 

Comment: 146.82 Required Class VI permit information - (e) ".... and any additional 

information the Director may require:" - this is good part, as we as a state 

have had numerous occasions when operators do not submit all of the information 

needed to determine the viability of an application for a well because it is not 

specifically listed in the state regulations 

Individual Response: The Agency believes that providing the Director discretion to request 

additional information will allow consideration of a range of sites for GS, based on site-specific 

conditions, and ensure USDW protection. EPA believes that requiring appropriate site 

characterization by the owner or operator (under §146.82) and providing an appropriate degree 

of flexibility to the Director to evaluate site-specific geologic data will afford the greatest 

protection of USDWs from endangerment. 

Letter ID: 0153 Comment ID: 22145 Letter Lines: 98 to 101 

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

Comment: 146.84 Area of review and corrective action - (b) (2) (i) the need to reevaluate the area of review a maximum of every 10 years - great clause, we have 

potential for problems in our Class II program where operators could potentially 

over inject, especially if the life of permit expires 

Individual Response: EPA acknowledges the commenters’ support for reevaluation of the AoR. 

Based on evaluation of the public comments on this topic, EPA has changed the minimum 

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

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

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

risk-based targeting of monitoring activities, and the unique nature of CO2 GS. 

In response to the comment that operators could potentially over-inject, EPA clarifies that the 

7
purpose of the requirement to perform an initial AoR delineation at §46.84(c)(1) is to predict, as 

closely as possible, the ultimate extent of the CO2 plume and pressure front. The reevaluation 

should be considered as adjustments to address changes that could not have been anticipated 

before injection commences. 

Letter ID: 0153 Comment ID: 22146 Letter Lines: 103 to 109 

Comment Code: 5432 2.9.1.1 Need to adjust financial responsibility mechanisms (seeking 

comment) 

Comment: 146.85 Financial responsibility - (b) need to re-evaluate AOR, CAP, P&A, and 

post-injection site care and closure plans and the financial resources needed to 

address them on a frequency set by Director - this prevents the initial 

determination of bonding from becoming inadequate in future - our Class II 

regulations set a specific amount that can not be changed over time, and allow 

for a group of wells to be covered under the same, inadequate statewide bonding 

mechanism 

Individual Response: EPA agrees and clarifies that the GS rule, at §146.85, requires the 

Director to evaluate the financial responsibility demonstration annually to confirm that the 

instrument(s) used remain adequate for purposes of protecting USDWs from endangerment. At 

§146.85(e), it states that if the Director determines during the annual evaluation that the original 

demonstration is no longer adequate to cover the cost of activities for which it is required, the 

owner or operator must provide an adjustment to the cost estimate within 60 days. EPA also 

clarifies that the GS rule, at §146.85(c)(2), 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. 

Letter ID: 0153 Comment ID: 22147 Letter Lines: 111 to 116 

Comment Code: 3820 2.3.1 Well construction procedures 

Comment: 146.86 Injection well construction requirements - (a) (2) well must be 

constructed such to allow appropriate testing devices and work-over tools - this 

is a good clause also, as our Class II regulations have allowed for a 

temporarily abandoned well that was worked over in such a way so it will be 

difficult to MIT it - may have to bring in an expensive R(adio)A(ctive)T(racer 

log) test rig - we couldn't prevent it under our Class II regulations 

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

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

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

8
and maintain integrity of the well throughout the lifetime of a GS project. This is the foundation 

of the requirements for construction of Class VI wells at §146.86. 

Letter ID: 0153 Comment ID: 22148 Letter Lines: 118 to 124 

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

Comment: (b) (2) extending surface casing through the base of the lower-most USDW - this 

may be over kill in areas where there are multiple aquifers at numerous 

different depths. Especially in areas where the upper USDWs easily fulfill the 

needs of the populace, and the deeper USDWs are of high TDS content, and may 

take considerable, expensive treatment to bring it to palatable levels. In 

addition, this would be more overkill if both the tubing and long string 

injection casings are cemented from bottom to surface. 

Individual Response: EPA disagrees that protecting deep USDWs underlying multiple, more 

shallow USDWs is "overkill." Protection of USDWs, regardless of their depth or stratigraphic 

location, is the primary mission and mandate of the UIC program—as specified by Congress in 

the SDWA—and the purpose of all requirements for injection wells. Any injection activity must 

be demonstrated to not endanger USDWs, regardless of their depth, and if such a demonstration 

cannot be made, then the activity will not be allowed under UIC requirements or the SDWA. 

Water agencies commenting on the proposed rule noted that diminishing water supplies are 

requiring water utilities to use deeper and more saline sources, and the SDWA mandates EPA to 

set regulations that protect USDWs from endangerment. 

The final GS rule at §146.86(b)(2) requires that surface casing extend through the base of the 

lowermost USDW and be cemented to the surface through the use of a single string or multiple 

strings of casing and cement. It does not, however, specify how cementing must be 

accomplished, and it allows the owner or operator to propose alternate methods that provide a 

sufficient amount of cement to meet the standard that USDWs are protected from endangerment. 

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

cementing. 

EPA recognizes concerns regarding construction of Class VI wells where the lowermost USDW 

is very deep. To further address comments on deep injection wells, the final GS rule at §146.95 

includes requirements for owners or operators that seek a waiver of the injection depth 

requirements. Owners or operators of wells operating under injection depth waivers must comply 

with additional construction requirements to ensure that wells used to inject above or between 

USDWs are protective. See the discussion of the waiver approach in the preamble to the final GS 

rule for additional information. 

Letter ID: 0153 Comment ID: 22149 Letter Lines: 126 to 129 

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

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Comment: (b) (3) at least one long string must extend to the injection zone and be 

cemented to the surface - same as comment for (b) (2) previous - especially if 

tubing is cemented from top to bottom, and long string is cemented into surface 

casing. 

Individual Response: As described above, EPA believes that protection of USDWs, regardless 

of their depth or stratigraphic location, is the primary mission and mandate of the UIC program 

and the purpose of all requirements for injection wells. 

The final GS rule at §146.86(b)(3) requires that the long-string casing extend to the injection 

zone and be cemented by circulating cement to the surface in one or more stages. It does not, 

however, specify how cementing would be accomplished, and gives flexibility to the owner or 

operator to propose alternate methods to provide a sufficient amount of cement to meet the 

standard that USDWs are protected from endangerment, subject to the approval of the Director. 

EPA recognizes concerns regarding construction of Class VI wells where the lowermost USDW 

is very deep. To further address comments on deep injection wells, the final GS rule at §146.95 

includes requirements for owners or operators that seek a waiver of the injection depth 

requirements. Owners or operators of wells operating under injection depth waivers must comply 

with additional construction requirements to ensure that wells used to inject above or between 

USDWs are protective. See the discussion of the waiver approach in the preamble to the final GS 

rule for additional information. 

Letter ID: 0153 Comment ID: 22150 Letter Lines: 131 to 133 

Comment Code: 4100 2.4.1 Injection parameters 

Comment: 146.88 Injection well requirements - (c) the annulus pressure needs to exceed 

the injection pressure - don't know why, as long as there is enough difference 

so sensors/gauges can indicate when something goes wrong. 

Individual Response: EPA believes that maintaining an annulus pressure that is higher than the 

injection pressure, as required at §146.88(c), will ensure that if there are leaks in the tubing, the 

annulus fluid will move into the tubing, rather than the injectate moving out of the tubing and 

potentially along the outside of the well. EPA believes this requirement is appropriate for Class 

VI wells given the potential high volumes and supercritical nature of the CO2 injectate, potential 

geomechanical stresses in the wellbore, and the potential for movement of the CO2 in the event 

of a mechanical integrity loss. 

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