This comment letter response contains two parts:   

(1) The original submittal from the commenter.

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

Notes about the response letters:

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

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

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

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

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

individual response. These are described and explained below.  

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

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

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

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

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

appropriately addressed.

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

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

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

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

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

construction requirements).  

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

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

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

commenter was given a unique response.

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

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

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

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

and attention to each comment letter that was submitted.   

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

Responses on each topic area are compiled and are also available in the rulemaking docket.
December 23, 2008

Water Docket

U.S. Environmental Protection Agency

Office of Water Docket (Mailcode 2822T)

1200 Pennsylvania Ave. NW

Washington, DC 20460

RE: Federal Requirements Under the Underground Injection Control (UIC) 

Program for Carbon Dioxide Geosequestration Wells, Proposed Rule EPAHQ-OW-2008-0390

Dear Water Docket:

The American Water Works Association (AWWA) and the Association of Metropolitan 

Water Agencies (AMWA) are submitting this joint letter to comment on the proposed 

Federal Requirements Under the Underground Injection Control (UIC) Program for 

Carbon Dioxide Geosequestration Wells. AMWA and AWWA together represent 

drinking water utilities of all sizes that serve more than 90% of the U.S. population. Our 

associations are very concerned with the effects of climate change on water resources 

and while we recognize the need for strategies to be developed that address mitigation 

of greenhouse gases (GHG), we also believe strongly that any strategy deployed for 

this purpose should above all else protect our water resources. 

Many of the most critical impacts of global climate change will manifest themselves 

through the hydrologic system, and there is already strong evidence that climate change 

is having an impact on the world’s water resources. In 2000, approximately 79% of 

54,000 community water systems in the United States were supplied by groundwater 

(almost 86 million people). In addition, many surface water utilities are currently looking 

at conjunctive use and/or groundwater development as adaptation measures (supply 

portfolio diversification/new storage) to combat climate change. There is the potential 

for each of these utilities to be impacted by geologic carbon sequestration, simply by the 

fact that these utilities utilize groundwater resources. 

 

This joint comment letter addresses recommendations on four issues that our 

organizations agree are critical for EPA to consider in finalizing the proposed rule. 

AWWA and AMWA are also each submitting a more detailed comment letter that raises 

these same issues in more detail, as well as additional key points.

The Authoritative Resource on Safe WaterSM
2

These four issues are:

• Protection of drinking water sources and potential future underground 

sources of drinking water (USDW) is paramount. As a result AMWA and 

AWWA recommend that:

o The permitting of large-scale geosequestration projects be delayed until 

information about Department of Energy (DOE) pilot projects and the 

effects of carbon sequestration on the subsurface and USDW can be 

collected and analyzed. We are concerned about the potential for carbon 

capture and storage (CCS) projects to result in unintended, and possibly 

harmful, consequences to sources of drinking water. Much of the work in 

CCS arena is still in pilot or pre-pilot phase at several magnitudes of scale 

smaller than the sort of projects envisioned under this proposal.

o The final CO2 geologic sequestration regulation should at a minimum, 

prohibit the construction of CO2 sequestration wells in any sole source 

aquifers and restrict any project in the vicinity of any sole source aquifer. 

• The USDW classification must be reconsidered when siting Class VI wells. 

The best sources of drinking water are already being used by utilities. Coupled 

with challenges resulting from climactic changes, population growth and land 

development, many utilities are turning to more challenging groundwater sources 

such as those that are very deep or have high salinity concentrations, also 

because the pumping costs for these deep wells are no longer prohibitive given 

the lack of sufficient water elsewhere. Some of these new sources could fall 

outside of the current definition of a USDW, in that the aquifer has a TDS 

concentration higher than 10,000 ppm. EPA’s proposed rule promises protection 

of USDWs from endangerment yet there are no anti-degradation provisions in the 

proposed regulation to protect other groundwater supplies, such as those 

aquifers that are not classified as a USDW but have been, or may be, identified 

as a future drinking water source. The TDS criterion was written at a time when 

many advanced water treatment technologies were generally cost prohibitive. In 

light of the changes in the hydrological and technological landscape, we 

recommend that EPA reexamine the classification of USDWs based on TDS 

when considering the siting of Class VI geosequestration wells. The potential 

need to use saline aquifers for potable supply, particularly in water-stressed 

areas, should take precedence over the sequestration of carbon dioxide there.

• Permits should be issued for five-year periods and not the life of the 

geosequestration project. In addition, an annual reevaluation of the project’s 

area of review (AoR) should be conducted for at least the first 10 years of a 

geosequestration project and then every five years for the remaining operating 

period of the project. CCS is a developing technology and additional data and 

research findings will be available regularly. Therefore, we recommend that EPA 

have a plan to update the regulation on a regular basis as well. Having a permit 
3

renewal schedule built into the rule will allow each state Director to ensure that 

updates to the regulation are included in permit renewals. AWWA and AMWA 

also suggest that the permit application process include a review of the site 

operations to see if any instances of unsafe operation or changes in regulation 

would require a change in the plant operation. 

• Theoretical and observational research must be continued and must be 

comprehensive. While the UIC program has a long history, the injection of CO2 

into the ground is a process that is not well understood. The substance is 

different and the behavior of the compound under severe pressures and 

temperatures is not well known. We strongly recommend that EPA and DOE 

perform both modeling (theoretical) and observational research to better 

understand the carbon sequestration process and the effects of CO2 injection on 

saline aquifers and the subsurface geology. The results of this research must be 

made available to permit writers and stakeholders so that improvements to the 

technology and permitting process can be realized.

AWWA and AMWA appreciate the opportunity to comment on EPA’s proposal. The 

proposed regulation is a good technical starting point given the need to have a federal 

standard to guide permit writers. However, the technology is still in its infancy and as a 

result we urge EPA to exercise caution and to ensure the protection of USDWs and 

future USDWs from harmful unintended consequences.

Sincerely,

Diane VanDe Hei Tom Curtis

Executive Director, AMWA Deputy Executive Director, AWWA

Cc: Cynthia Dougherty, OGWDW

 Steve Heare, OGWDW
Letter ID: 0206 

Commenter: Diane VanDe Hei 

Organization: Association of Metropolitan Water Agencies (AMWA) 

Letter ID: 0206 Comment ID: 22205 Letter Lines: 26 to 41 

Comment Code: 1280 1.1.2.1 General comments on climate change/ global warming 

Comment: U.S. population. Our associations are very concerned with the effects of climate 

change on water resources and while we recognize the need for strategies to be 

developed that address mitigation of greenhouse gases (GHG), we also believe 

strongly that any strategy deployed for this purpose should above all else 

protect our water resources. 

Many of the most critical impacts of global climate change will manifest 

themselves through the hydrologic system, and there is already strong evidence 

that climate change is having an impact on the world’s water resources. In 2000, 

approximately 79% of 54,000 community water systems in the United States were 

supplied by groundwater (almost 86 million people). In addition, many surface 

water utilities are currently looking at conjunctive use and/or groundwater 

development as adaptation measures (supply portfolio diversification/new 

storage) to combat climate change. There is the potential for each of these 

utilities to be impacted by geologic carbon sequestration, simply by the fact 

that these utilities utilize groundwater resources. 

Individual Response: The Agency agrees that protecting drinking water is important. The 

primary goal of the UIC program under the SDWA is to protect USDWs. The UIC program 

provides that no injection shall be authorized if it results in the movement of fluid containing any 

contaminant into USDWs, if the presence of that contaminant may cause a violation of any 

primary drinking water regulation under 40 CFR §141 or may adversely affect the health of 

persons (§144.12). 

The GS rule, as part of the UIC program regulations, continues the Program’s goal of ensuring 

the protection of USDWs from endangerment. The purpose of the Class VI GS rule is to ensure 

consistency in permitting underground injection of CO2 at GS operations across the United 

States and provide requirements to prevent endangerment of USDWs in anticipation of the 

eventual use of GS to reduce CO2 emissions. The permitting, siting, construction, operation, 

monitoring, and post-injection site care requirements in the Class VI GS rule are built on a longstanding protective regulatory framework, tailored to the unique aspects of CO2 GS. 

Letter ID: 0206 Comment ID: 22207 Letter Lines: 50 to 60 

Comment Code: 1610 1.3.1 Risks to USDWs 

Comment: - Protection of drinking water sources and potential future underground sources 

1
of drinking water (USDW) is paramount. As a result AMWA and AWWA recommend that: 

o The permitting of large-scale geosequestration projects be delayed until 

information about Department of Energy (DOE) pilot projects and the effects of 

carbon sequestration on the subsurface and USDW can be collected and analyzed. 

We are concerned about the potential for carbon capture and storage (CCS) 

projects to result in unintended, and possibly harmful, consequences to sources 

of drinking water. Much of the work in CCS arena is still in pilot or pre-pilot 

phase at several magnitudes of scale smaller than the sort of projects 

envisioned under this proposal. 

Individual Response: EPA believes that sufficient data and experience currently exist to 

develop regulations under the UIC program for Class VI wells. The GS rulemaking builds upon 

decades of knowledge about safe underground injection practices regulated by the UIC Program. 

While developing the GS regulations, EPA has evaluated relevant GS research, including 

projects conducted by the seven Regional Carbon Sequestration Partnerships (RCSPs) funded by 

DOE and coordinated through the National Energy Technology Laboratory (NETL), and several 

international projects. 

Several large-scale pilot projects are currently underway worldwide to test the appropriateness 

and efficacy of various technologies to characterize sites, ensure proper well construction and 

operation, and monitor injection activities and CO2 plume and pressure front distribution. EPA is 

tracking international GS efforts and is aware of four commercial-scale projects that are 

currently in operation: the Sleipner Project in the Norwegian North Sea (operating since 1996); 

the Weyburn ER project in Saskatchewan, Canada (since 2000); the In Salah Gas Project in 

Algeria (since 2004); and Snohvit, also in offshore Norway in the Barents Sea (since 2008). 

Other projects EPA is tracking include Gorgon and Otway (in Australia); Ketzin (in Germany); 

Lacq (in France); and CarbFix (in Iceland). 

Activities at Weyburn, In Salah, Sleipner, and the RCSP sites have been supervised by leading 

industry scientists and practitioners. Activities at Weyburn have also been peer-reviewed by the 

IEA-GHG Programme, an international collaborative research program that includes the 

European Commission and OPEC as members. EPA has considered the results of these pilot 

projects and data from RCSPs in developing the GS rule. 

EPA recognizes that technologies will evolve and improve over time, and for these reasons, the 

Agency is using an adaptive approach to regulate GS injection. The Agency plans, every six 

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

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

modifications to the requirements are appropriate or necessary. 

Letter ID: 0206 Comment ID: 22208 Letter Lines: 50 to 51 ; 62 to 64 

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

Comment: - Protection of drinking water sources and potential future underground sources 

2
of drinking water (USDW) is paramount. As a result AMWA and AWWA recommend that: 

o The final CO2 geologic sequestration regulation should at a minimum, prohibit 

the construction of CO2 sequestration wells in any sole source aquifers and 

restrict any project in the vicinity of any sole source aquifer. 

Individual Response: The GS requirements are designed to ensure protection of USDWs from 

endangerment by requiring that injection wells are permitted, sited, constructed, operated, 

monitored, and plugged in a manner that does not endanger USDWs. GS in areas that may pose 

risks to USDWs, as assessed and identified by the owner or operator and the Director during the 

site selection process, would not be permitted. 

EPA clarifies that §146.82(a)(5) requires prospective owners or operators to submit information 

on all USDWs (which would include sole source aquifers) within the AoR. The Director would 

consider this information and the potential impact of the GS project on any sole source aquifers 

in determining whether GS is acceptable. 

Letter ID: 0206 Comment ID: 22209 Letter Lines: 66 to 84 

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

ownership 

Comment Code: 1610 1.3.1 Risks to USDWs 

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

Comment: - The USDW classification must be reconsidered when siting Class VI wells. The 

best sources of drinking water are already being used by utilities. Coupled with 

challenges resulting from climactic changes, population growth and land 

development, many utilities are turning to more challenging groundwater sources 

such as those that are very deep or have high salinity concentrations, also 

because the pumping costs for these deep wells are no longer prohibitive given 

the lack of sufficient water elsewhere. Some of these new sources could fall 

outside of the current definition of a USDW, in that the aquifer has a TDS 

concentration higher than 10,000 ppm. EPA’s proposed rule promises protection of 

USDWs from endangerment yet there are no anti-degradation provisions in the 

proposed regulation to protect other groundwater supplies, such as those 

aquifers that are not classified as a USDW but have been, or may be, identified 

as a future drinking water source. The TDS criterion was written at a time when 

many advanced water treatment technologies were generally cost prohibitive. In 

light of the changes in the hydrological and technological landscape, we 

recommend that EPA reexamine the classification of USDWs based on TDS when 

considering the siting of Class VI geosequestration wells. The potential need to 

use saline aquifers for potable supply, particularly in water-stressed areas, 

should take precedence over the sequestration of carbon dioxide there. 

Individual Response: The Agency acknowledges commenter concerns about water resources 

and future water resource availability. However, modifying the definition of a USDW is outside 

3
the scope of the GS rulemaking. USDWs are defined as aquifers currently being used as sources 

of drinking water or those capable of supplying a public water system and they have a total 

dissolved solids (TDS) content of 10,000 milligrams per liter or less (§144.3). 

The primary goal of the UIC Program under the SDWA is to protect USDWs in order to ensure a 

reliable supply of drinking water for the American public. The GS rule, as part of the UIC 

program regulations, continues the program’s tradition of ensuring the protection of USDWs. 

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

requirements in the GS rule built on a long-standing protective regulatory framework, tailored to 

the unique characteristics of CO2 GS. 

Letter ID: 0206 Comment ID: 22210 Letter Lines: 86 to 87 

Comment Code: 5700 2.12 Comments on the proposed duration of Class VI permits (seeking 

comment) 

Comment: - Permits should be issued for five-year periods and not the life of the 

geosequestration project. In addition, an annual reevaluation of the project’s 

Individual Response: The final rule maintains the lifetime permit provision and clarifies that the 

permit extends through the post-injection site care period (144.36(a)). However, it also adds a 

requirement that the Director review each Class VI permit at 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). This is preferable to a periodic permit 

reapplication. 

Letter ID: 0206 Comment ID: 22211 Letter Lines: 87 to 90 

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

4
Comment: geosequestration project. In addition, an annual reevaluation of the project’s 

area of review (AoR) should be conducted for at least the first 10 years of a 

geosequestration project and then every five years for the remaining operating 

period of the project. CCS is a developing technology and additional data and 

Individual Response: EPA agrees with commenters that reevaluations of the AoR every ten 

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

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

reasons, the Agency 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 addition, the Director has discretion to require more 

frequent AoR reevaluation if he or she has reason to believe, based on site-specific information, 

that a five-year reevaluation schedule is not sufficiently protective of USDWs. 

Letter ID: 0206 Comment ID: 22212 Letter Lines: 90 to 92 

Comment Code: 1200 1.1 General comments about the rulemaking 

Comment: period of the project. CCS is a developing technology and additional data and 

research findings will be available regularly. Therefore, we recommend that EPA 

have a plan to update the regulation on a regular basis as well. Having a permit 

Individual Response: The final rule is based on the most recent GS-related data, information, 

and scientific research available. EPA plans, every six years, to collect and review data on GS 

projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are 

appropriate or necessary. An adaptive approach provides Class VI owners or operators the 

flexibility to use and apply newly developed technologies for GS as they become available in the 

future. 

Please see the remainder of EPA's responses to this comment for further details. For additional 

information on EPA's final regulatory approach, please see the final rule and preamble as well as 

the rulemaking docket. 

Letter ID: 0206 Comment ID: 22213 Letter Lines: 92 to 97 

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

comment) 

Comment Code: 5700 2.12 Comments on the proposed duration of Class VI permits (seeking 

comment) 

Comment: have a plan to update the regulation on a regular basis as well. Having a permit 

renewal schedule built into the rule will allow each state Director to ensure 

5
that updates to the regulation are included in permit renewals. AWWA and AMWA 

also suggest that the permit application process include a review of the site 

operations to see if any instances of unsafe operation or changes in regulation 

would require a change in the plant operation. 

Individual Response: The final rule maintains the lifetime permit provision and clarifies that the 

permit extends through the post-injection site care period (144.36(a)). However, it also adds a 

requirement that the Director review each Class VI permit at 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). This is preferable to a periodic permit 

reapplication. 

EPA adds that, in addition to the requirement that the Director review the permit every 5 years, 

as part of existing requirements at 40 CFR 144.39, the Director has the authority to revise the 

permit if project operations change, if the Director believes based on monitoring or operational 

data that the project may endanger USDWs, or if the regulations change. EPA has also added 

text to 144.39(a)(5) saying that permit modifications may be required if the Director determines 

that a modification is necessary based on an AoR reevaluation, amendments to any of the project 

plans, or a review of the testing and monitoring results. The Director may also choose to require 

minor permit modifications under 40 CFR 144.41, depending on the extent of the plan 

amendment. All permit modifications, except minor modifications under 40 CFR 144.41, require 

an opportunity for public comment on the portion of the permit that is being reopened. 

Letter ID: 0206 Comment ID: 22214 Letter Lines: 99 to 108 

Comment Code: 1510 1.2.2.3 Need for additional study 

Comment: - Theoretical and observational research must be continued and must be 

comprehensive. While the UIC program has a long history, the injection of CO2 

into the ground is a process that is not well understood. The substance is 

different and the behavior of the compound under severe pressures and 

6
temperatures is not well known. We strongly recommend that EPA and DOE perform 

both modeling (theoretical) and observational research to better understand the 

carbon sequestration process and the effects of CO2 injection on saline aquifers 

and the subsurface geology. The results of this research must be made available 

to permit writers and stakeholders so that improvements to the technology and 

permitting process can be realized. 

Individual Response: EPA agrees that continued research in all GS associated fields will be 

integral to development of GS technology. EPA is aware of research by other federal agencies, 

industry, international parties, and academia related to GS, including projects that address many 

of the topics suggested by commenters. EPA published a Notice of Data Availability (NODA) 

and Request for Comment on August 31, 2009 (74 FR 44802), in which the Agency described 

the results of research at three DOE partnership sites (in Escatawpa, Mississippi; the Aneth Field 

in Paradox Basin, southeast Utah; and the Pump Canyon Site, New Mexico). In the NODA and 

Request for Comment, EPA also described two studies by the Lawrence Berkeley National 

Laboratory on the potential effects of CO2 injection on ground water and surrounding formations 

to determine the potential for impacts on USDWs and human health in the event that a GS 

project is not properly sited, operated, or managed. 

To protect USDWs from endangerment and meet the potentially fast pace of GS deployment, 

EPA is using an adaptive approach to regulating CO2 injection for GS. The Agency plans to, 

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

amount and types of information and appropriate documentation are being collected, and to 

determine if modifications to the requirements are appropriate or necessary. An adaptive 

approach will allow regulatory development to proceed in time to meet the current and future 

demands for Class VI permits, while EPA continues to gather data from pilot projects and other 

research as it becomes available. 

Letter ID: 0206 Comment ID: 22215 Letter Lines: 110 to 114 

Comment Code: 1410 1.2.1 Comments in support of EPA/rulemaking 

Comment Code: 1610 1.3.1 Risks to USDWs 

Comment: AWWA and AMWA appreciate the opportunity to comment on EPA’s proposal. The 

proposed regulation is a good technical starting point given the need to have a 

federal standard to guide permit writers. However, the technology is still in 

its infancy and as a result we urge EPA to exercise caution and to ensure the 

protection of USDWs and future USDWs from harmful unintended consequences. 

Individual Response: As described above, EPA recognizes that injecting large volumes of CO2 

for GS poses unique challenges that, if not properly managed, could endanger drinking water 

sources or have other adverse impacts. EPA agrees that caution is warranted and has, as a result, 

developed a new well class with requirements tailored to address the unique challenges posed by 

GS and potential risks associated long-term injection of CO2. These requirements include the 

tailored AoR delineation process per §146.84, monitoring that is appropriate to GS projects per 

§146.90, and extended post-injection site care per §146.93. 

7
8

As part of its adaptive rulemaking approach, The Agency plans, every six years, to collect and 

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

information and documentation are being collected, and to determine if modifications to the 

requirements are necessary. 

Also, as EPA noted above the Agency believes that sufficient data and experience currently exist 

to develop regulations for Class VI wells. EPA has considered the results of past research in 

developing the GS rule.