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

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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.
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December 12, 2008

Water Docket

Environmental Protection Agency

Mailcode 2822T

1200 Pennsylvania Avenue, NW

Washington, DC. 20460

RE: Docket EPA-HQ-OW-2008-0390, Federal Requirements lmder the

Underground Injection Control Program for Carbon' Dioxide Geologic

Sequestration Wells Proposed Rule - 73 FR 43492, July 25, 2008

Dear Sir/Madam:

In response to the U.S. EPA proposed rule on geologic sequestration

(73FR43492), the National Ground Water Association submits the attached

general and specific comments.

NGWA i(l a not-for-profit professional society and trade association for the

ground water industry. Our 14,000 members include some of the country's

.Ieading public and private sector ground water scientists, engineers, water well

contractors, manufacturers and suppliers of ground water related products and

services. The Associ>ttion's visio'n is to be the leading community of ground

water professionals that promotes theresponsible development, use and

management of ground water resources.

If you have questions about NGWA or these comments, please don't hesitate to

contact me at 800.551.7379, ext. 560 or creimer@ngwa.org.

Sincerely,

Christine Reimer

Government Affairs Director

national . Clrf>L.lrH1 vvater

.J aSSOclatlon®

Address/ 601 Dempsey Road' Westerville, Ohio 43031 ~8978 USA

Phone/ TolI·Free 800 551.7379/614 898.7791 Fax/614 898.778G

E-mail! ngwJ@ng\'lJ.org \'11'11'1/ ngwJ,org and l'iellowner.org
National Ground Water Association Comments on Geological Sequestration Proposed Rule

Comments

on

Federal Requirements under the Underground Injection Control

Program for Carbon Dioxide Geologic Sequestration Wells

Proposed Rule - 73 FR 43492, July 25, 2008

Docket - EPA-HQ-OW-2008-0390

Submitted

December 12, 2008

By

National Ground Water Association

601 Dempsey Road

Westerville, OH 43081

800.551.7379

Contact: Christine Reimer

1
National Ground Water Association Comments 011 Geological Sequestration Proposed Rule

Comments on Federal Requirements Under the Underground Injection

Control Program for Carbon Dioxide Geologic Sequestration Wells

Proposed Rule - 73 FR 43492, JUly 25, 2008

Docket - EPA-HQ-OW-2008-0390

The National Ground Water Association (NGWA) is a not-for-profit professional society

and trade association for the ground water industry. Our 14,000 members include some

of the country's leading public and private sector ground water scientists, engineers,

water well contractors, manufacturers and suppliers of ground water related products

and services. The Association's vision is to be the leading community of ground water

professionals that promotes the responsible development, use and management of

ground water resources.

In response to the U.S. EPA proposed rule on geologic sequestration (73FR43492),

NGWA submits the following general and specific comments:

Definition of Underground Sources of Drinking Water

NGWA recommends that US. EPA reevaluate the appropriateness of the definition of an

underground source of drinking water (USDW) as one containing less than 10,000 ppm

total dissolved solids prior to large-scale licensing of carbon capture and storage (CCS)

sites to ensure future drinking water supplies are not unintentionally degraded. For

example, a recent article reported that deep brackish ground water, approximately

12,000 TDS, is under consideration as a water source for a development in Sandoval

County, New Mexico. The article notes that the cost of water treatment is expected to

be less than obtaining existing water rights (Sengebush, 2008) In 2003, water managers

in 36 states anticipated shortages in localities, regions, or statewide in the next ten years

(U.S. General Accounting Office, 2003). The potential for the increased use of brackish

ground water for water supplies must be anticipated and considered.

Classification of Injection Wells for Carbon Sequestration, Class II Injection Well

Transition, and Grandfathering

The EPA published a guidance document in March of 2007 recommending that the

geologic sequestration experimental projects during this period of research use the

Class V experimental category for classification of the injection wells (Using the Class V

Experimental Technology Well Classification for Pilot Geologic Sequestration Projects -

EPA 2007). These projects are currently underway at the Department of Energy's

(DOE's) National Energy Technology Laboratory Regional Partnership test sites. Thus,

there will be a need in the future for a regulatory mechanism for transition of these

Class V experimental wells to Class VI operational status. There are also a number of

Class II enhanced oil recovery (EOR) wells that have been used for testing of the

sequestration process. These wells, too, may need a mechanism for transition to Class

VI for operational use.

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National Ground Water Association Comments on Geological Sequestration Proposed Rule

The NGWA Carbon Sequestration Task Force recommends that the experimental

phase extend beyond the regional partnerships to each site proposed for productionscale injection of carbon dioxide. It is recommended that at least one well at each site

be constructed under the Class V experimental category, and that testing of the

adequacy of the geologic environment for geologic sequestration of carbon dioxide be

conducted prior to permilling any well in the Class VI category at the site.

The transition of carbon dioxide injection wells from Class II (Enhanced Oil Recovery

wells) to Class VI (carbon sequestration wells) will presumably be requested when

production of the petroleum has ceased. Liquid carbon dioxide from a distant source,

such as a power plant, can be stored in the depleted petroleum reservoir even after

production has ceased, necessitating a change in classification of the injection well.

The new use of the wells involves much longer storage time, and raises concerns about

mechanical integrity and long term effects, including geochemical changes, on

underground source of drinking water (USDWs). The reclassification should depend on

a positive outcome from a Class V experimental program conducted in the depleted

reservoir, as described below.

The "grandfathering" of Class V carbon sequestration wells would mean allowing

experimental wells to be permitted for operation after the testing period is over. The

NGWA Carbon Sequestration Task Force recommends that each carbon sequestration

system or wellfield have an experimental phase, and not rely on results from distant

experimental locations. Thus, nearly every operational well would start as a Class V

experimental well, or would go through a Class VI testing phase, before being permitted

for long-term operation. The transition to Class VI operational status would require

demonstrating that the minimum requirements are met at that location. Most wells

would go through the following permitting phases:

• Class V experimental well construction permit: This permit would allow

geologic and geophysical testing, aquifer testing, laboratory work, etc, but

would not include injection of CO2 (only potable water injection testing would

be allowed).

• Class VI experimental well operational testing permit: At this stage, the full

monitoring facilities would need to be constructed. This permit would allow

test injection of liquid CO2 at rates high enough to demonstrate that the

location meets the minimum requirements for operation, for a period of up to

two years.

• Class VI operation permit: After demonstrating that the location and the well

meet all the minimum requirements for injection of CO2, the operation permit

can be issued.

The goals of the experimental well Class V construction permit would be to make the

following demonstrations:

• A receiving zone of sufficient depth, area extent, thickness, porosity, and

permeability is present;

3
National Ground Water Association Comments on Geological Sequestration Proposed Rule

• Lithologic description, geological name, thickness and depth of each

confining unit above the storage aquifer, and of each USDW.

• A trapping mechanism that is free of pathways for migration of injected

fluids into a USDW. These pathways may include major non-sealing faults,

porous beds within the confining unit, changes of facies trending toward

more porous units and man-made structures such as wells or mine shafts.

A trapping mechanism is defined as a geologic environment that prevents

vertical and horizontal movement of fluids into a USDW; The volume of the

trap shall exceed the proposed total volume of injected carbon dioxide for

the life of the proposed facility

• Identification of all confining units between the primary injection/storage

zone and the lowermost USDW, and their adequacy to contain the injected

fluid. Unless the only feasible injection zone has only one confining unit

separating it from the lowermost USDW, this demonstration includes

adequacy of confinement for both the primary confining unit and a

secondary containment system that extends to the base of the lowermost

USDW and is completely redundant of the primary confining system and

could confine the injected CO2 should the primary system fail. In locations

where the secondary containment system is not possible, the applicant

shall propose an alternative system of early warning of failure of the primary

confining unit in order to avoid impacting any USDW should that

confinement fail. This demonstration applies in the horizontal sense as

well, demonstrating one or more mechanisms containing the fluid from

horizontal movement into a USDW in the storage aquifer at a distant

location.

• The construction of an operational monitoring system meeting all the

requirements described in this document's MMV section, and

demonstration of the adequacy of this system to meet those requirements.

• Demonstration of mechanical integrity

Having made the foregoing demonstrations, a Class VI operational testing permit can be

issued for a period of up to two years. The goals of the experimental well Class VI

operational testing permit would be to make the following demonstrations:

• A hydraulic demonstration of the adequacy (depth, area extent, thickness,

porosity, and permeability) of the storage zone, using monitoring data and

4-D seismic monitoring of the extent of the CO2 plume.

• Demonstration of the adequacy of the trap for 5/10 years of injection at the

proposed rate. The volume of the trap shall exceed the proposed total

volume of injected carbon dioxide for the 5/10 years of the first operation

permit.

• Demonstration of the adequacy of confinement under operational

conditions using monitoring data and a method of detecting the extent of

the CO2 plume in the storage aquifer, such as 4-D seismic monitoring or

direct sampling.

• Re-evaluation of the Area of Review and extent of the zone of endangering

influence.

• Re-evaluation of mechanical integrity, using the buoyancy of the injected

CO2 to better measure external mechanical integrity. The re-evaluation

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National Ground Water Association Comments on Geological Sequestration Proposed Rule

shall include the testing required during the initial MIT, as well as evaluation

of the cement for carbonation, or chemical weathering by CO2

Under this permitting scenario, the vast majority of Class V experimental wells would be

constructed after the Class VI standards had been published. The "grandfathering" of

Class V wells that do not meet the Class VI construction standards would only be

needed for DOE test sites established before rulemaking was complete. If these wells

include the ongoing mechanical integrity monitoring of annular fluid pressure and

composition, and they pass periodic mechanical integrity testing, they should be able to

follow the same permitting procedures to become operational Class VI wells.

Geologic Characterization

The UIC program is required under the Safe Drinking Water Act to protect USDWs from

contamination from fluids injected into the subsurface. Part of this requirement is the

demonstration that the injected fluids will not migrate, through buoyancy, ground-water

flow or injection pressure, into USDWs. This demonstration is based on the

characteristics of the geological environment where injection is to take place. The

current UIC regulations require investigation of waste disposal sites through an

application-phase data summary (Area of Review study) and geologic testing while

drilling the pilot hole of the injection well. In general, the critical attributes of the injection

and confining units are measured during pilot hole drilling, and the integrity and extent of

those units are addressed in the literature review and Area of Review study at the

application phase. Because of the large volumes of carbon dioxide that are expected to

be injected, and the vast extent of the storage zones, it is expected that more detailed

information will be needed over a larger area for carbon sequestration than has been

historically needed for injection of other wastes.

The NGWA recommends that the adequacy and safety of injection of liquid carbon

dioxide at each site be evaluated by multi-phase, variable density ground-water

modeling, supported by extensive field investigations (see section General Comments

on the Use of Modeling for Ground-Water Protection Related to CO2

Sequestration, below) These models should be included at the experimental well

permit application phase as conceptual models, and progressively refined as data are

collected during well construction and testing, and monitoring of operations.

The test injection wellfoperational testing permit application for a carbon sequestration

injection well must address the geological characteristics of the site. The data presented

at this stage should be adequate to make and calibrate an appropriate ground-water

model. The necessary elements of the geologic system for carbon sequestration

include:

• A receiving zone of sufficient depth that the injected carbon dioxide can be

maintained in a supercritical state

• Of sufficient areal extent that it includes the entire zone of endangering influence

• Of sufficient thickness and porosity to contain the volume of carbon dioxide injected

over the life of the proposed system

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National Ground Water Association Comments on Geological Sequestration Proposed Rule

• Of sufficient permeability to accept the peak daily flow of injected carbon dioxide

from the facility

• A trapping mechanism (consisting of either impermeable barriers or

geochemical/mixing barriers) that is free of vertical or horizontal pathways for

migration of injected fluids into a USDW. The volume of the trap shall exceed the

proposed total volume of injected carbon dioxide for the life of the proposed facility

• A primary confining system of sufficient areal extent, thickness and competency to

contain the injected fluid at proposed rates and volumes without initiating or

propagating fractures in the confining zone

• Unless the only feasible injection zone has only one confining unit separating it

from the lowermost USDW, a secondary containment system that is completely

redundant of the primary confining system and could confine the injected CO2

should the primary system fail.

• The identification of a monitoring zone between the primary and secondary

confining units. In locations where the secondary containment system is not

possible, the applicant shall propose a monitoring formation to provide early

warning of failure of the primary confining unit in order to avoid impacting any

USDW should that confinement fail.

• Provide depth and completion information of all USDWs that may be affected by

the injection if fluid movement does occur.

• Provide geochemical information on subsurface aquifers, including all USDWs:

Baseline geochemical data on water-rock- CO2 geochemistry and mineral

reactions, maps and cross sections.

These elements should be identified in existing well records, in geologic literature, and

by using the results of the exploratory program. The critical storage and confining units

should be shown to exist over the entire area of review, or zone of endangering

influence

The operation permit application should also include a preliminary multi-phase

numerical transport model for CO2 and formation fluid, including all of the elements

listed above. This model should include at least one calibration scenario and will be

used to provide a preliminary evaluation of the adequacy and safety of injection of

carbon dioxide at the site, as well as a preliminary calculation of the potential storage

volume of the geologic structure.

Each permit application for a carbon sequestration injection well must include an Area of

Review study, which addresses the entire zone of endangering influence of the carbon

sequestration operation, including the area impacted after cessation of injection due to

buoyancy transport. The zone of endangering influence shall be determined by the

ground-water model described above and illustrated with maps and cross sections.

Provide information on the geologic structure of the proposed site, including:

• Maps and cross sections of local geologic structure. Each cross section should

include the location and depth of relevant data sources, including geophysical logs,

that were used in developing the cross section

• Geologicai name and lithologic description of each injection zone, primary and/or

secondary confining unit, and USDW

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National Ground Water Association Comments on Geological Sequestration Proposed Rule

• Data on the receiving formation and the confining systems:

1. Size of the storage reservoir, and extent of the confining units in

comparison to the area of endangering influence

2. Presence or absence of a secondary confining unit

3. Porosity, and permeability of the storage zone and confining units, including

any geology/facies changes, based on field data which may include

geologic cores, outcrop data, 3-dimensional seismic surveys, and well logs

4. Capacity of the storage zone in comparison to the proposed total volume of

carbon dioxide to be stored,

5. Evaluation of the long-term effectiveness of the storage structure, including

expected pathways of migration of injected carbon dioxide, and the

horizontal barriers to fluid movement

• Geomechanical information on fractures, stress, rock strength, and in situ fluid

pressures within the primary and secondary containment units and confining

systems

• Identification of potential pathways for migration of injected fluids and determination

that they would not conduct a volume of fluid that would cause a violation of the

prohibition of fluid movement as it applies to the class of well that is to be

constructed

• Identification of potential risks within the zone of endangering influence, including

degradation of water quality in USDWs, gas buildup in USDWs, reduction of

porosity through geochemical changes in USDWs, and popUlation that could be

affected by gas releases.

• List of penetrations into the injection zone and secondary containment system.

• Information on seismic history and the presence/depth of seismic sources

During drilling and construction of the injection well, important, site-specific data must be

collected to verify the facts included in the application, provide quantitative data for

refinement of the ground-water model, and test the injectivity of the proposed injection

zone. The testing currently recommended in the regulations during construction of Class

I wells includes geophysical logs run during drilling, deviation checks to ensure that

reamed holes do not deviate from pilot holes, leaving conduits in the formation, and logs

to measure the integrity of the completed wells. The NGWA recommends the following

testing during construction:

A. Identification of the lowermost USDW should be confirmed during drilling, using

tests such as the following:

1. Sampling discharge from packer tests (straddle packers or single-packer bottomhole test).

2. Cross plots of induction or resistivity with sonic/neutron/density porosity

measurements and deduction of fluid resistivity using Archies Law (verification of

porosity with core samples)

3. Bottom-hole water sampling during pilot hole drilling (with mud)

4. Depth sampling in pilot hole while pumping

5. Collection, logging, and archiving, of rock cores through the sealing and target

formations.

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7
National Ground Water Association Comments on Geological Sequestration Proposed Rule

B. The demonstration of confinement is the most critical task in construction of the

well. Some information can be collected only prior to the installation of casing so

careful consideration should be given to formation sampling before the well is

completed. We recommend that borehole geophysical methods, such as, but not

limited to, resistivity, neutron, gamma, and density logs, be combined with

formation imaging such as, but not limited to, digital video and acoustic

televiewer logging to specify lithologic units, geologic properties, and faults or

fractures. Hydraulic testing such as straddle packer injection can be completed

prior to completion of the well. After completion, long-term pumping tests should

be conducted over a sufficient time period to assure near-pseudo-steady state

head conditions in the vicinity of the well. Interpretation of these data and tests

should be used to refine the ground-water flow and transport model.

General Comments on the Use of Modeling for Ground-Water Protection Related

to CO2 Sequestration

Quantitative modeling must play an important role in the assessment of ground-water

protection related to CO2 sequestration projects. A 'quantitative model' is defined here

as a quantitative mathematical analog of the real subsurface system.

Three overall purposes for quantitative modeling are generally recognized:

1. Generic: Model used in a hypothetical sense

2. Interpretive: Model used to understand system dynamics

3. Predictive: Model used to predict future behavior of the subsurface system.

All three purposes are generally needed for a CO2 sequestration project. For example,

generic models are used to determine the important physical or geochemical

mechanisms that dominate transport or trapping of CO2• An interpretive model is

applied to test specific hypotheses regarding these behaviors. Predictive modeling

provides the basis for design of the final injection scheme and establishment of potential

risk to drinking water.

Quantitative models may range from simple anaIvtic calculations to complex multicomponent multi-phase coupled three-dimensional numerical simulations. The choice of

quantitative model (analytic or numerical) depends in large part on the ultimate objective

of the modeling study, and on practical constraints including availability of data and

computational limitations. Which type of model or combination of models is most

appropriate for a specific situation depends on many factors. In general, using a

combination of modeling and analysis techniques is recommended, because different

levels of complexity are needed at various stages of a project and for different

objectives, and application of multiple modeling techniques can be used for "crosschecking" and overall quality assurance.

Numerical models are widely available and usually represent a relatively wide range of

physical and chemical processes, spatial heterogeneity of material properties, and

nonlinear interactions among different processes. While these kinds of models allow for

substantial flexibility and can provide detailed predictions of system behavior, they also

8
National Ground Water Association Comments on Geological Sequestration Proposed Rule

require large amounts of data, much of which may be difficult to obtain or estimate. As

such, specific choices of models must be made with care, and some situations may most

effectively be addressed by a combination of different kinds of models.

Quantitative modeling, whether conducted with analytical or numerical modeling tools,

provides significant insights into system behavior. The advantages of such models are

that they:

1. provide a framework for data collection centered about a specific set of transport

and geochemical behaviors.

2. allow communication and the interpretation of these data in the context of

scientific principles and facilitate collaboration among engineers, scientists, and

regulators.

3. may be extended far into the future using multiple design scenarios

4. can be compared to measured data which allow hydraulic and geochemical

parameters to be estimated.

5. Can be used to access the performance of the system in a long performance

period for which field and laboratory data are not available.

It is important to recognize that all quantitative mathematical models are based upon a

"conceptual model" which defines the important fluid and chemical interactions as well

as the spatial and temporal extent of the model. Because the conceptualization is a

critical part of the modeling activity, it is important to explore multiple conceptual models

during the modeling process to assure that important scenarios are not excluded from

the analysis.

The selection of which quantitative model to use relies on the identification of the

physical/chemical parameters and functions that must be represented. Because the

injection and migration of CO2 into the subsurface is hydraulically and chemically

complex, comprehensive quantitative modeling would have to include many parameters

and factors -- including the flow of miscible and immiscible phases in all potential states

as well as chemical reactions among fluids and with the geologic media and necessary

heat transfer. The geologic medium may also deform or be chemically altered in

response to the presence of CO2 . The complexity of these coupled processes, in the

presence of complex hydrostratigraphy, lead to models that are at the limit of the current

capabilities of available computer hardware and software. It is likely, therefore, that

multiple models may be required to provide the necessary insights into the important

physical and chemical processes. Ultimately, sound scientific and engineering

judgments should be applied to determine which physical or chemical processes are

most important for a given analysis, and to make assumptions that are consistent with

those judgments. For example, during the injection phase of a CO2 operation, multiphase flow physics tend to dominate other processes such as interphase mass transfer

and geochemical reactions. This separation of time scales can lead to important

simplifications for the purpose of risk assessment. Similar analysis of spatial scales can

provide additional simplifications, leading to practical modeling tools for the purpose of

risk assessment. It is, therefore. imperative that modeling experts participate and

manage all phases of the modeling process, in concert and constant communication with

the project team and the appropriate regulatory reviewers, to ensure that appropriate

and comprehensive quantitative modeling tools are applied successfully."

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The process of comparing simulated and measured predictions for the purpose of

developing a more accurate depiction of a subsurface flow system is generally referred

to as "model calibration" in the ground-water literature. (This same process is referred to

as "inverse modeling" in exploration geophysics and "history matching" in petroleum

reservoir simulation.) Model calibration involves varying the parameters of the

quantitative model to achieve the minimum difference between measured and predicted

responses. This is usually achieved through an automated process using non-linear

regression or a heuristic algorithm to optimize the problem (e.g. as implemented in the

PEST or UCODE software). In the case of ground-water modeling, the predicted and

measured data are usually pressures, discharge rates, or concentrations of fluids or

dissolved species. These data may not be available during the design stage of a CO2

project unless wells already exist in the target formation. As wells are drilled and

geologic and fluid information are collected, however, the model should be refined and

calibrated. Most automated calibration procedures allow for statistical estimation of

confidence in the estimated parameters, providing a basis for quantifying the sensitivity

of the model to changes in its parameters, and for performing quality control of model

predictions.

The design, construction, and calibration of analytic or numerical models should follow a

quality assurance and quality control procedure. These procedures should include

benchmarking of the mathematical predictions against known results, a method for

assuring input data quality and lineage, and a statistical analysis of the predictive results

against available data and/or sensitivity analyses. ASTM guides are available for

ground-water modeling and code benchmarking (e.g. Guides D 6025, D 5447, D 5490, D

5611, D 5609, D 5610, and D 5718).

Use of commercial proprietary codes should be authorized. Proprietary doesn't mean

secret. A proprietary code largely vetted by the industry can be the best application in

many circumstances. To promote peer review and benchmarking, the assumptions and

theories for all numerical models should be publicly available and the solution of any

analytic equations used in the predictive process should be fully elaborated.

Area of Review and Corrective Action

In the context of carbon storage, NGWA thinks it is important to distinguish between the

CO2 plume footprint and the zone of elevated pressure. The rationale is given in the next

section, but the following conditions should be met:

No fixed radius can be used, a zone of endangering influence (ZEI) must be

determined through modeling (but cannot be smaller than Y.i mile in its smallest

horizontal dimension)

In the volume generated by the CO2 plume footprint (plus appropriate buffer) (this

volume is defined as the "primary AOR"): all penetrations between the base of

the injection formation and the base of the USDW should be reviewed and any

necessary corrective action should be taken before start of project.

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National Ground Water Association Comments on Geological Seqllestration Proposed Rule

In the elevated pressure area but outside of the CO2 plume footprint (defined as

the "secondary AOR"), all current penetrations through the primary seal and the

injection formation should be reviewed. However the applicant should be allowed

to perform corrective action in a pseudo-concentric phased manner ahead of and

according to the development of the pressure plume.

Secondary AORlzone of elevated pressure cannot be computed independently of

other injection projects in the vicinity. The impact of other sequestration projects

must be included in determining injection rate / period of injection.

Primary and secondary AOR must be periodically reviewed to ensure that

modeling predictions are met. If they are not, the primary and secondary AOR

should be revisited. The operator should keep track of any new penetration in the

primary AOR volume and secondary AOR (for example, for oil and gas industry).

"Primary AOR" - Why "Volume of Review"

Because CO2 is strongly buoyant, it is not sufficient only to investigate penetrations in

the injection formation and primary seal. The whole volume potentially contacted by the

CO2 plume should be reviewed. The review and corrective actions should be performed

before the start of injection because there is no stopping the CO2 migration once started.

The greatest degree of effort should be on the deeper wells in the injection zone and

primary containment then on the secondary containment and seal (if any) and then on

shallower wells but as many as possible of the shallower wells should be compiled too.

Delayed Corrective Action for "Secondary AOR"

A simple time-dependent secondary AOR that expands as the volume of injection

increases and the CO2 migrates is not acceptable. The secondary AOR should be

agreed upon and reviewed before injection starts but corrective action can be somewhat

delayed. The secondary AOR consists of only the injection formation and seal as used in

the current rules because only brine/formation water leakage is an issue in the elevated

pressure area. The likely presence of a large elevated pressure area does not make

realistic imposing corrective action on all wells before the start of a project. There is no

need to provide corrective action to wells before the pressure significantly rises. If

another problem (e.g., CO2 leakage) occurs earlier at another location and injection

stops, pressure will not keep rising and will drop. In addition, delaying corrective action

will allow taking advantage of technical improvements that will undoubtedly occur in the

next decades.

Modeling is Needed: When considering tens of miles, trying to use conservatively the

analytical solution as provided in 40 CFR §146.06 will likely generate unrealistically large

AORs. Parameters such as formation thickness and heterogeneity, storativity and

permeability values will likely vary in the zone of elevated pressure suggesting that

model results should be accepted as valid.

How to define the edge of the AOR? If the CO2 plume is relatively easy to define in

terms of modeling, this is much less true for the pressure plume. Limits to the secondary

AOR can be defined more or less as it is currently done by the contour line of the

11

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National Ground Water Association Comments on Geological Sequestration Proposed Rule

additional pressure that would push the injection formation brine beyond some elevation

threshold (for example, 100 ft below the base of the USDW). Time-varying area where

corrective action needs to take place as injection progresses can be defined in a similar

fashion.

AORs can be initially defined solely on the basis of modeling. However, NGWA strongly

supports that a satisfactory match between prediction and actual field measurements

needs to be assessed as the project progresses.

Fluid Movement

The UIC regulations have, from the beginning, included two standards of prohibition of

fluid movement that may be appropriate for geological sequestration of carbon dioxide.

The fluid movement requirement for Class I injection wells states:

The well must be constructed, operated, maintained, and plugged such that

injection activities will not cause movement of any contaminant into a USDW

The fluid movement requirement for Class V injection wells states:

No owner or operator shall construct, operate, maintain, convert, plug, abandon,

or conduct any other injection activity in a manner that allows the movement of

fluid containing any contaminant into underground sources of drinking water, if

the presence of that contaminant may cause a violation of any primary drinking

water regulation under 40 CFR part 142 or may otherwise adversely affect the

health of persons. The applicant for a permit shall have the burden of showing

that the requirements of this paragraph are met.

The NGWA recommendation for carbon sequestration well permitting includes an

experimental phase for each location that will be used for geological sequestration of

carbon dioxide. Wells constructed during the experimental phase at each location will

have extensive testing requirements and exploratory objectives that will not be needed

during the operational phase. It will not be necessary or practical to apply the same

standard of fluid movement to both the experimental phase and the operational phase of

carbon sequestration.

The NGWA recommendations also include early warning monitoring to detect movement

of fluids containing carbon dioxide or contaminants before the fluids reach a USDW.

The advantage of early warning monitoring is in the ability to detect fluid movement

before a drinking water supply is impacted. The identification of a geological unit that

can serve as secondary containment for the injected fluid is addressed in the NGWA

recommendations for geologic characterization. It is recommended that early warning

monitoring be included in the requirements for operation of Class V experimental carbon

sequestration wells, as well as Class VI operational carbon sequestration wells. The

requirement for early warning monitoring should include authorization for action by the

regulatory agency when fluid movement is detected by the early warning monitoring

system.

12

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National Ground Water Association Comments on Geological Sequestration Proposed Rule

Class V Experimental Carbon Sequestration Well: During the experimental phase of

injection, while the well is permitted as a Class V well, the following fluid movement

criterion should apply:

No owner or operator shall construct, operate, maintain, convert, plug, abandon, or

conduct any other injection activity in a manner that allows the movement of fluid

containing carbon dioxide or any contaminant into underground sources of drinking

water, if the presence of carbon dioxide or that contaminant may cause a violation

of any primary drinking water regulation under 40 CFR part 142 or may otherwise

adversely affect the health of persons. The applicant for a permit shall have the

burden of showing that the requirements of this paragraph are met.

Class VI Operational Carbon Sequestration Well: During the operational phase of

injection, while the well is permitted as a Class VI well, the following fluid movement

criterion should apply:

No owner or operator shall construct, operate, maintain, convert, plug, abandon, or

conduct any other injection activity in a manner that allows the movement of fluid

containing carbon dioxide or any contaminant into underground sources of drinking

water, if the presence of carbon dioxide or that contaminant may cause a violation

of any primary drinking water regulation under 40 CFR part 142 or may otherwise

adversely affect the health of persons. Additionally, no owner or operator shall

construct, operate, maintain, convert, plug, abandon, or conduct any other injection

activity in a manner that allows the movement of carbon dioxide in gaseous phase

to land surface, nor limit the extraction of drinking water from a underground

sources of drinking water by reduction of porosity or changes in pH or water quality

due to geochemical reactions, or by causing a buildup of gas in the underground

sources of drinking water. The applicant for a permit shall have the burden of

showing that the requirements of this paragraph are met.

If any water quality monitoring of an underground source of drinking water

indicates the movement of any contaminant into the underground source of

drinking water, or a violation of any part of the preceding paragraph, except as

authorized under part 146, the Director shall publish a notice in newspapers of

general circulation in whose service area the fluid movement was detected. If a

meritorious request is submitted by the public, the Director shall prescribe such

additional requirements for construction, corrective action, operation, monitoring, or

reporting (including closure of the injection well) as are necessary to prevent such

movement.

Well Construction, Testing, and Closure

Wells will be an integral part of a CO2 sequestration operation. Wells will be used to

inject CO2 into the target sequestration formation and monitor the sequestration and

other formations that could be affected by the injection. Because wells represent a

potential conduit for CO2 or formation fluids to move out of formation and possibly to the

surface great care must be taken to construct wells such that they will not leak, monitor

them to ensure that they do not start leaking, and close them to ensure that they do not

13

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National Ground Water Association Comments on Geological Sequestration Proposed Rule

become a leakage risk later. Wells must demonstrate the ability to contain both injected

and native fluids without allowing significant movement between formations or to the

surface.

Construction

Regardless of the site specific component the new wells will need to be designed to

meet the overarching goals for all projects. The goals for and injection well will be to

inject CO2 and to keep fluid from moving along the wellbore between formations or to the

surface. The goals for a monitoring well are to monitor the injection or other formations

and also to keep fluids from moving along the wellbore. To accomplish these goals the

design of the well needs to address site-specific, objective-specific (monitoring or

injection), and fluid-specific considerations. All injection wells should be cased and

cemented to stop fluid movement between formations. A surface casing should be

installed and set below the lowermost USDW above the injection zone and cemented

along its entire length. It is important when considering the height of the cement sheath

behind the long-string casing to consider the overall "design" of the injection and

monitoring zones. Because, it is ideal to have a secondary caprock it will be imperative

to cement the well, at a minimum, from the injection zone to a level above the secondary

confining unit. If the borehole through the secondary caprock is left uncemented the

effectiveness of the secondary caprock will be greatly reduced. Furthermore, it may be

advisable to cement the casing along the entire length to protect the casing from

degradation due to anodic dissolution [Anstice et aI., 2005] or exposure to corrosive

formation fluids. If the casing is not cemented along its entire length it may be

necessary to use cathodic protection, depending on the site, to keep the casing from

degrading. Watson and Bachu, [2007] found that about 81 % of wells in their study area

that had surface casing vent flows (leaks) had them above the top cemented section.

The materials used for construction need to be compatible with the injected fluid and

compatible with the formation fluids. Both injection and monitoring wells should be

constructed to the same material standard unless there is an objective-specific reason

not to, because they may both be subjected to similar aggressive down-hole conditions.

In order to insure that proper wellbore construction materials are always selected a

standard should be adopted that specifies wellbore materials should resist the expected

downhole conditions to a sufficient degree such that degradation will not lead to leakage.

The thicknesses of the casing and tubing must be sufficient to handle the pressure

associated with the injected CO2 . Although materials are an important aspect in well

construction centralization of the casing is also important for insuring the cement job is

successful. It is very important that the casing is centralized over the entire cemented

section. This will provide the best condition to achieve full radial coverage of the cement

between the casing and the formation.

For both types of wells, it is important that regulations require that internal safety

measures are installed in the well. This will help ensure that wells do not allow leakage

out of the well through the wellbore in the case of an accident or other event. Down-hole

shutoff equipment needs to be required. The shutoff equipment needs to be downhole

to avoid leakage if the surface components of the well are damaged.

14

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National Ground Water Association Comments on Geological Sequestration Proposed Rule

In some areas it is likely that existing wells will be converted into both injection wells and

monitoring wells. It seems unlikely that such wells will have been constructed to the

same standard as wells purpose-built for sequestration applications. This, however, is

probably not reason enough to rule them out from being used as long as they meet the

same standards for protection as new wells do. This said, there should be a cutoff date

so that all wells used for CO2 injection or monitoring constructed after the date are

constructed to the same standard.

Injection wells should be designed to inject through tubing. Tubing and packer allow for

monitoring pressure in the annulus between the tubing and casing to help identify any

leaks. Furthermore the tUbing can be replaced relatively easily in the case any damage

to the tubing is identified or to change the diameter of the tubing.

Wellbore Integrity Monitoring and Measurement

The integrity of monitoring and injection wells must be established and monitored.

However, the type of integrity measurement(s) should be decided upon based on the

construction of the well, the well materials, and the effectiveness of the monitoring

techniques. Wells that are not cemented from total depth (TO) to the surface should be

subject to more integrity monitoring than those that are cemented from TO to surface

because the path behind the uncemented section of casing could act as a fast path for

fluids to move between formations. No single specific monitoring technique should be

required and it is expected that multiple techniques will be needed. The deviation of all

wells should be measured to ensure that the geometry of the well is understood to

identify areas that may require special attention, like poorly centralized sections, to

ensure that they are carefully characterized.

A requirement will be needed to ensure that the integrity and quality of the casing and

cement job are initially and remain sufficient to prevent flUid movement along the

wellbore. Because the cement is behind the casing, it will be necessary to use some

type of logging tool to make the measurement. The selection of logging tools should be

based on proven performance. The prescription of a particular tool may force the use of

a technology in the future that is not the best available for the job. This said, the

standard for selection of the tool can be specified and should take into account the

geometry of a wellbore. Because wells are cylindrical, the integrity and location of the

cement must be verified using technology capable of radially evaluating and mapping

the cement, identifying the location of channels or contaminated cement, and validating

the casing-cement and cement-formation bonds, thus providing a 3600

map of the

cement and any potential defects for the entire length of the cemented casing.

Another method of ensuring the mechanical integrity of the well is the use of mechanical

integrity tests, MITs. MITs, that raise the pressure in the well, like the standard annulus

pressure test, are often used to measure the internal integrity. It is possible that the

increase in pressure in the wellbore associated with some MITs could damage the

interface between the casing and the cement possibly creating a leakage pathway. The

use of these MITs on CO2 injection wells should be studied before it is made a

requirement. MITs such as radioactive tracer surveys, RATS, or other alternative

methods with comparable results, may be more appropriate for measuring internal

15

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National Ground Water Association Comments on Geological Sequestration Proposed Rule

integrity. Furthermore, RATS and temperature logging may also be an effective

technique for identifying external wellbore leakage pathways.

The integrity of the well should be measured on a regular basis such that time-lapse

comparisons are possible to see if there are changes within the wellbore over time that

could lead to leakage situations.

Closure

When all injection operations are finished the site will be closed and the post closure

period will begin. At this juncture the injection wells will be plugged and abandoned.

The plugging needs to be done such that the CO2 and formation fluids cannot use the

wellbore as a conduit when it is complete. No wells should be abandoned until there has

been a final round of measurements to verify the integrity of the well in case remedial

action is needed prior to plugging. Wells plugged prior to the site closure phase should

be plugged and abandoned following the same procedures as those in the closure

phase. Any requirements need to ensure that all wells are properly plugged and

abandoned using material and methods that will allow the well to remain safe and not

become an avenue for leakage.

Monitoring, Measurement, and Verification

Measurement, monitoring, and verification (MMV) will be a key task for all geologic

carbon sequestration operations. MMV should be looked at as a continuation of the

measurements that were collected during the characterization and construction phases

as described in the sections on well construction, testing, and closure and geologic

characterization. Characterization and construction measurements will provide the

baseline for comparison during the injection and post injection phases of the

sequestration project. The data collected during the MMV will be used to insure the site

is not leaking or for the identification and remediation of leaks. The data will also be

used to calibrate and reduce uncertainty in models of the site.

During the operational injection phase of a CCS project, MMV can be broken into

operational monitoring, which is the monitoring of the injected CO2, and environmental

monitoring, which is the monitoring of the subsurface including the sequestered CO2 and

the associated pressure front.

Operational MMV includes; monitoring the volume, flow rate, and composition of CO2

that is injected. The injection pressure must be low enough that injection does not

propagate new fractures and does not open existing faults or fractures for flow through

the caprock or damage the containment properties of the injection well. The operational

monitoring will also have to monitor the injection and monitoring wells to ensure they are

functioning properly and not allowing any leakage. The integrity of the injection well must

be monitored internally and externally to ensure that there is no degradation that could

allow CO2 to leave the target formation. Well integrity monitoring through the use of

logs, annulus pressure monitoring, and mechanical integrity tests is covered in detail in

the section on well construction, monitoring and abandonment.

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16
National Ground Water Association Comments on Geological Sequestration Proposed Rule

Environmental MMV needs to be implemented to collect data from the four or more

geologic formations that comprise the subsurface site: the storage formation, the primary

cap rock, the monitoring formation, and the secondary cap rock. MMV must also provide

information on shallow formations, including the lowermost USDW, that contain drinking

water, the surface and, any potential leakage pathways between the storage formation

or monitoring formation and any drinking water formations or the surface (this may

include additional monitoring of wells above what is required for operational monitoring).

In the injection zone, monitoring must identify the location of the injected e02 and the

associated pressure front. MMV in the monitoring zone should be geared to ensure that

any vertical migration across the cap rock is identified. Monitoring of USDWs should be

set up to look for changes that would be associated with the presence of e02 or eo2-

displaced brine. While some general monitoring points in all of these zones will be

needed, it may be more practical to locate monitoring points or take measurements near

locations identified during the characterization and potential fast-paths, such as

abandoned wells, existing wells, or faults and fractures. One location that may provide

the best use of monitoring resources is near the injection weil. This is the most likely

location for upward fluid movement without specific knowledge of a potential leakage

pathway. Leakage could occur either through mechanical integrity failure or defects, or

failure or defects of the confining units. Monitoring, in the monitoring zone and lowest

USDW in addition to the injection zone, provides a vertical pressure profile, measures

stress on the confining units, and may detect water quality changes.

In the monitored zones, geochemical and fluid chemical information should be based on

constituents identified in the characterization as likely indicators of leakage. These

indicators will likely include the pH and also be identified in the major and minor

chemical constituents of the formation and ionic constituents of the formation-fluid.

The methods used for monitoring on projects to date have included time-lapse seismic,

passive seismic, pressure logging, temperature logging, neutron saturation logging, fluid

sampling, air sampling [IPee, 2005]. While it is probably not appropriate to specify the

suite of MMV tools to be used at every site, because not all tools will work at all sites, it

is important to emphasize that multiple MMV technologies will be required at every site

in order to completely monitor and collect the necessary data to verify that the site is

operating within the bounds of its permit. Although it seems unreasonable to specify all

MMV technologies, it does seem reasonable to specify that monitoring wells be installed

to collect the necessary fluid samples, pH, resistivity, and pressure data. Also, although

seismic monitoring may not work everywhere, in locations where it is expected to work it

should be incorporated into the monitoring scheme. Seismic monitoring for e02 plume

location has been successfully employed in early projects including Sliepner storage

project, Weyburn storage project, and Frio brine project [IPee, 2005, Wilson and

Monea, 2005, Daley et aI., 2007]. The data collected from monitoring should be used to

update and verify the site's performance and risk models.

In addition, to aid in selecting other MMV technologies, the International Energy Agency

has developed a comprehensive database that can be accessed at:

http://www.c02captureandstorage.info/c02tool v2.1 beta/index.php

17

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National Ground Water Association Comments on Geological Sequestration Proposed Rule

Although surface monitoring may be needed from a community outreach and

environmental safety point of view, it is important to note that by the time any leakage is

detected at the surface it will have already passed by and possibly impacted

underground drinking waters. Projects like the Frio brine project [McCallum et ai, 2005]

have incorporated tracers as a way to identify CO2 leakage. The use of non-isotopic

tracers, tracers other than C13, C14, and 018 that occur naturally in CO2 , should be

studied very carefully for unintended environmental effects prior to implementation.

Once injection ceases permanently, the operational portion of MMV can also cease.

This period, called the closure period, is the time in which the operator will plug and

abandon all wells that will not be used for further monitoring. Environmental MMV

operations should continue throughout this period using the same suite of techniques as

in the operational phase.

MMV should be conducted hand-in-hand with modeling over the entire period that MMV

is occurring, with each new round of measurements being incorporated into a new

iteration of the appropriate site models. An iterative measurement-modeling approach

will allow for the best understanding of the shape and size of the AoR. It will also help

identify areas of uncertainty in the model that may be reduced with changes in the MMV

plan. Changes identified in the size of the AoR and for risk of leakage will help ensure

that MMV is carried out at the right frequency and in the right locations. The timing of

the MMV operations should be flexible and adjustable based on the performance of the

site and the site models. It is likely that the site data from early in the operation will

probably be more valuable than data from later in the operation for assessing the

performance of the site and identifying and reducing uncertainties. MMV operations that

are not continuous should be conducted more frequently at the start of the operational

phase and then be allowed to become less frequent if the site is performing safely and in

concert with the model predictions. The initial, more frequent monitoring should be

specified in the permit as an experimental phase of the injection project. The

continuation of injection should be contingent upon successful containment of the

injected CO2 during the experimental phase.

As the pressure in the injection zone starts to stabilize it may be possible to lengthen the

period between measurements if the reservoir is performing as expected based on the

calibrated site models. When the location of the CO2 either stops changing or can be

predicted and validated against measurements over multiple measurement cycles, the

ownership of the site and the responsibility for future MMV, if deemed necessary, may

be transferred from the operator to the government, starting the post-closure phase. If

the site is not behaving as expected, an iterative MMV-modeling approach will help

identify areas of uncertainty that can be reduced by changes in the MMV plan to collect

more or different data to determine the site's performance.

Regulations for the operational phase need to ensure that a licensed Carbon Capture

and Storage (CCS) site is operated safely and should allow for flexibility in the

monitoring schedule based on the performance of the site and site models. A site that is

performing well probably reqUires less frequent monitoring than one that is not

performing well. A long-term match between MMV data and site modeling results

probably indicates a good understanding of the site and shouid be one of the criteria

used to decide when the custodianship of the site should be transferred from the

91"6'8\\~ w~ter assocIanon'

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18
National Ground Water Association Comments on Geological Sequestration Proposed Rule

operator to the government. It is possible that iterative MMV and modeling will show that

the AoR changes over time. The idea of a variable AoR should be included and

accepted in any regulations. The results of the MMV and modeling including the

integrity of the wells, fluid properties and volumes, subsurface location of the plume,

leakage monitoring, modeling, and size of the AoR should be reported at least annually

or upon a sudden significant change.

Overview of Financial Responsibility Issues

Introduction

Applying financial responsibility for the various operational and post-closure risks is

central to widespread deployment of CCS as an effective climate-change mitigation

strategy. The commonly perceived CCS categories of risks include toxicological effects,

induced seismicity, subsurface trespass, and climate effects (de Figueiredo et aI., 2006).

The mechanisms for these risks include CO2 gas leakage from the injection wellhead;

gas leakage from geologic reservoir; development of injection-related seismicity in

existing seismically active areas; and, degradation of drinking water aquifers by

mobilization of brines or by geochemical interaction of fugitive CO2 with overlying

aquifers.

These liabilities may be further categorized in terms of operational liability and postinjection liability (e.g., Figueiredo et aI., 2006). Operational liability includes the

environmental, health and safety risks associated with capture, transportation and

injection of CO2• Post-injection liability is related to storage of carbon dioxide in the

geologic formation after it has been injected. According to Figueiredo et aI., postinjection liability can be further divided according to (1) in situ liability of harm to human

health, the environment, and property, including degradation of aquifers, and (2) climate

liability related to leakage of CO2 from the geologic reservoirs and its long-term effect on

climate change.

The long period and geographic scale over which these liabilities can occur pose unique

challenges for assessing CCS liability, in comparison to conventional business liability

models. For example, the operational phase of individual CCS projects is anticipated to

be tens of years (Gerard and Wilson, 2008). Although the post-injection risks are inferred

to decrease with time, the long period over which these risks may manifest themselves

and the inherent geophysical uncertainties of geologic reservoirs are not amenable to a

strictly private solution to liability. For example, several authors (e.g., Figueredo et aI.,

2006; Edison Electric Institute, 2007; WRI, 2006; and Gerard and Wilson, 2008) have

suggested that the unique liabilities associated with CCS should be assigned to the

operators during the injection phase and for a short period after cessation of injection

and closure of the injection wells, and the long-term post-closure liability should become

a public responsibility because of the perceived significant public benefit that CCS will

have on iocal and global climate. Another reason to involve the public sector in the longterm liability may be to ensure that a responsible entity will be around (i.e., should the

CCS operator or holding company become insolvent) to address post-closure CCS

problems, should they arise (World Resources Institute, 2007).

19

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National Ground Water Association Comments on Geological Sequestration Proposed Rule

Applicable and Relevant Liability Models

Public health/environmental liability models currently exist in North America that may to

offer some insights to help develop workable CCS liability policy to safeguard public

interests yet remain attractive to private/corporate investors who will help fund

development of the required CCS technology and large-scale CCS operations.

Alberta Acid Gas Re-lnjection. Acid gas streams, consisting primarily of hydrogen sulfide

and carbon dioxide, are commonly generated as a by-product of the gas "sweetening"

process used to bring produced natural gases and solution gases up to pipeline

specifications for sales and transport. Prior to introduction of acid gas re-injection,

treatment of acid gases included flaring. The province of Alberta has over 38 acid gas

re-injection wells in operation (Wong et aI., 2003). In Alberta, the injection well operator

is financially responsible (liable) for operation and closure of acid gas re-injection wells,

but there is no responsibility for post-closure monitoring or mitigation of gas leaks,

whether leakage is from the storage reservoir or from the closed injection well (Bachu,

2007). In addition, there is no provision to ensure that "orphaned" (abandoned) reinjection wells are closed properly by a public or private entity, should the operator

becoming insolvent.

Price-Anderson Act. The Price-Anderson Act was passed as federal law in the United

States in 1957 to partially indemnify the nuclear industry against liability claims for

nuclear incidents while still protecting the general public. The Act established a no-fault

insurance fund in which the first $10 billion of an incident claim is funded by industry and

the federal government covers the remainder over this amount. The federal government

instituted this Act to provide an incentive for private investment In nuclear power; without

this type of indemnification, investors were unwilling to accept the unquanilifed risks of

nuclear energy. Although criticized by some groups!, the Act has been renewed several

times and is currently set to expire in 2025. The Act appears to focus primarily on liability

for nuclear plant operation and not for post-closure incidents. Over the first 43 years of

operation until 2000, the secondary federal insurance has not been required. The

nuclear industry has paid a total of $151 million to cover claims, including $70 million for

the Three Mile Island incident. During the same period, the Department of Energy has

paid about $65 million to cover claims for its own nuclear operations.

Resource Conservation and Recovery Act (RCRA). Enacted by the U.S. Congress in

1976, RCRA mandates that companies set aside funds for post-closure care of solid and

hazardous waste sites, and establishes EPA's authority to control related wastes from

"cradle-to-grave" (USEPA(a), downloaded 2008). For example, solid waste landfill

operators in most U.S. states bear financial responsibility for public health and safety,

environmental health, environmental monitoring, landfill maintenance, and

remediation/treatment of leachate and contaminated ground water during landfill

operation and for a post-closure period. Financial assurance of ability to cover these

costs is generally required as a condition of the operator's state permit for both the

operating and post-closure period. Some states (e.g., Maine) require that the financial

assurance cost estimates be based on the entire expected time that the solid waste

1 Criticized as a form of subsidy for industry, for failing to hold industry fully accountable for

commercial nuclear safety, and for industry/contractor indemnification even under situations of

gross negligence.

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20
National Ground Water Association Comments on Geological Sequestration Proposed Rule

facility is expected to be generating leachate, landfill gases and other contaminants that

have a potential for creating an adverse environmental impact. Pennsylvania bases

bonding estimates on a 30-year post-closure period, but final closure is performancebased and site specific; upon final closure determination, a 10-year bond liability period

commences. However, the operator and landowner are still liable beyond this period for

adverse effects and other changes in site conditions. Other states require post-closure

monitoring, remediation and financial assurance for a finite period (e.g., Ohio - 30 years;

Vermont - 20 years).

In 1986, Congress created a Leaking Underground Storage Tank (LUST) Trust Fund by

amending Subtitle I of RCRA. The LUST Trust Fund provides money for overseeing and

enforcing corrective action by a responsible party, and for cleanup at UST sites where

the owner is unknown, unable, or unwilling to respond (USEPA(b), downloaded 2008).

The Trust Fund is financed by a 0.1 cent tax on each gallon of motor fuel. All 50 states

have cooperative agreements with EPA to spend this money for LUST-related activities.

In addition, 47 states have established state-run LUST Funds to help owners and

operators with UST upgrades and LUST remediation problems (Tiemann, 1999).

Reimbursements from the state LUST Funds have generally benefited most UST

owners/operators who comply with the existing state and federal UST regulations,

regardless of finanCial ability to cover these costs. Like the RCRA LUST Trust Fund, the

state LUST Funds are generated through gas taxes and tank fees.

Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA).

CERCLA (also referred to as Superfund), enacted by the U.S. Congress in 1980,

established a tax on the chemical and petroleum industries to finance a fund that

addresses the liabilities arising from the clean up of hazardous waste sites. Over a

period of five years, $1.6 billion was collected and the tax went into a trust fund for

cleaning up abandoned or uncontrolled hazardous waste sites (USEPA(c), downloaded

2008). CERCLA was amended in 1986 by the Superfund Amendments and

Reauthorization Act (SARA). SARA increased the size of the trust fund to $8.5 billion

(USEPA(d), downloaded 2008). While RCRA was intended to be forward-looking,

CERCLA is intended to be backward-looking, i.e., contamination that occurred prior to

RCRA authorization.

Tiered Approach

A key tenet of environmental laws and regulations is that pollution costs should be borne

by their creators. U.S. environmental laws and regulations give this principle form by

making polluters liable for property, health, and natural resource damages and

unperformed resource reclamation obligations (Boyd, 2001). However, the anticipated

great public benefit from CCS implementation and reluctance of private investors to

become involved in an enterprise that may have several hundred years of post-closure

liability suggest that a shared private/public liability model may be appropriate for longterm post-closure phase of CCS.

Gerard and Wilson (2008) provide a temporally-tiered approach to managing liability for

all phases of CCS. This approach relies on operator liability and use of operator-funded

bonds to cover liability during the operational phase (Phase 1) of CCS. Gerard and

Wilson report that this approach has been used effectively for many oil and gas wells

21
National Ground Water Association Comments on Geological Sequestration Proposed Rule

and wells regulated under the UIC Program where the operational lifetime of the wells is

tens of years. This surety mechanism and time frame may also encourage proper site

management and well closure for CCS wells. Short-term post-closure liability (Phase 2)

for unanticipated accidents would rest with the operator, but active bonding by the

operator would cease. Monitoring and verification during Phase 2 would be financed by

publicly run or pooled financial mechanisms that would be funded by operator/industry

contributions during the active injection phase of the project. The third phase of liability

and management (Phase 3) would be a public responsibility, ensuring that long-term

standards of care are met.

According to Gerard and Wilson, demarcation of the Phase 2 to Phase 3 transition could

be performance-based (e.g., based on pressure levels in the CCS reservoir or on

dissolved CO2 in the formation fluid), or prescriptive (e.g., after a finite period [10 years,

25 years, etc.]). By Phase 3, project performance and success are more certain and

public "liability" and management would be viewed as primarily administration and

record-keeping.

USEPA's Proposed UIC CCS Rule

In the proposed UIC CCS Rule, USEPA is proposing a combination of fixed timeframe

and a performance standard. Post-injection site care (monitoring) would occur for a

period of 50 years. This period could be shortened or lengthened based on plume

behavior. If monitoring data demonstrate that the plume/pressure front is stabilized and

the CO2 injectate does not pose risk to USDWs, the 50-year post-injection site care

period could be shortened. Conversely, if the plume/pressure front has not stabilized

after 50 years of post-injection monitoring, USEPA would extend the monitoring period

until stabilization is achieved.

Conclusion

It is apparent that much work and public-private sector discussions are needed to

develop a liability policy framework and details that are workable and acceptable to all

parties. In recognition of this, USEPA is requesting public comments on their proposed

50-year monitoring period with a performance element. Developing effective

performance-based criteria upon which to base transfer of post-closure liability to the

public appears to be an area that warrants considerable technical research. This

transition mechanism could become one of the key issues to gain public acceptance for

CCS.

The Task Force recommends that federal and energy industry funding for CCS research

be directed toward establishing performance-based indicators for CO2 reservoir stability

to facilitate liability transfer. This tiered approach may offer ample incentives to ensure

that CCS operations are managed responsibly, yet not discourage investors from

supporting CCS. Public assumption of Phase 3 liability after the CCS reservoir stabilizes

appears commensurate with the great public benefit that CCS offers.

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22
National Ground Water Association Comments on Geological Sequestration Proposed Rule

Acknowledgement

NGWA acknowledges the Association's Geologic Sequestration Task Force for their

work in developing comments on geologic sequestration and EPA's proposed rule. Task

force members include:

Glenn Amey

PPL Services Corp

Allentown, PA

Andrew Duguid, PhD

Schlumberger Carbon Services

Pittsburgh, PA

Matthew W Becker PhD

University of Buffalo

Buffalo, NY

Michael Celia, PhD

Princeton University

Princeton, NJ

William Cocke

Dept. of Natural Resources and

Environmental Conservation

Dover, DE

Jean-Philippe Nicot, PhD

Bureau of Economic Geology

University of Texas

Austin, TX

Steven R Pinette, Certified Geologist

SW Cole Engineering

Scarborough, ME

Robert P Schreiber, PE, BCEE, D.wRE

CDM (Camp Dresser & McKee Inc.)

Cambridge, MA

Chen Zhu, PhD

Indiana University

Dept of Geological Sciences

Bloomington, IN

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23
National Ground Water Association Comments on Geological Sequestration Proposed Rule

References

Anstice, D.J., Page, C.L., and Page, M.M., 2005, "The pore solution phase of carbonated cement

pastes," Cement and Concrete Research, Vol. 35, pp. 377-383.

Bachu, S., 2007, Legal and Regulatory Aspects of CCS, in Workshop on Capacity Building for

Emerging Economies. Carbon Sequestration Leadership Forum in Porto Alegre, Brazil.

Boyd, J., 2001, Financial Responsibility for Environmental Obligations: Are Bonding and

Assurance Rules Fulfilling Their Promise? Discussion Paper 01-42, Resources for the

Future.

Daley, T.M., Solbau, RD., Ajo-Franklin, J.B., and Benson, S.M., 2007, "Continuous activesource seismic monitoring of CO2 in a brine aquifer," Geophysics, Vol. 72, No.5, pp.

A57-A61.

Edison Electric Institute, 2007, Status and Outlook for Carbon Capture and Storage Technology

in the United States. Written statement for the U.S. House Select Committee on Energy

and Global Warming.

Figueiredo, M. de, D. Reiner, H. Herzog, and K. Oye, 2006 The Liability of Carbon Dioxide

Storage. Presented at the Eight International Conference on Greenhouse Gas Control

Technologies, Trondheim, Norway

Fernando, H. J. Venezia, C. Ridgon, and P.Verma, date??, Capturing King Coal: Deploying

Carbon Capture and Storage Systems in the U.S. at Scale. World Resources Institute

and Goldman Sachs.

Gerard, D., and E.J. Wilson, 2008, Environmental Bonds and the Problem of Long-Term Carbon

Sequestration. Source. Journal of Environmental Management, In Press. Available

online as of July 2008:

http://www.epp.cmu.edu/csir/ContentiResearch/Carbon%20Capture%20and%20Seguestration/Gerard%20

Wilson%20Bonding.doc

Intergovernmental Panel on Climate Change, 2005, IPCC special report on carbon capture and

storage, United Nations Framework Convention on Climate Change, ISBN 92-9169-119-

4.

Maine Dept. of Environmental Protection, rev. 2001, Maine Solid Waste Management Rules,

Chapter 400: General Provisions.

g'i'6'8'h"il water aSSOCiation'

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Pc"",," 1~1,f,... Ku 5\1 ]l7~ fj\4 ~~l.]J-l' fa>! fjl1 HH71>5

w•."..·~-,.r·J""-O'i"·O"·h"··''''"'''':(J;'l

M'lrmfQJl £:I<"-~"'f Fa!JW'....u{t~ 01-,'0 430;31 ,8'l)~ USA

24
National Ground Water Association Comments on Geological Sequestration Proposed Rule

McCallum, S.D., Riestenberg, D.E., Cole, D.R., Freifeld, B.M., Trautz, R.C., Havorka, S.D., and

Phelps, T.J., 2005, "Monitoring geologically sequestered CO2 during the Frio brine pilot

test using perfluorocarbon tracers," Proceedings of the 4th Annual Conference on

Carbon Capture and Sequestration, May 2-5, 2005, Monitor and Exchange Publications

and Forum, Washington, D.C.

Sengebush, Robert M., INTERA, Inc. Deep Brackish Water Considered for New Mexico

Development. Southwest Hydrology, March/April 2008, p. 8.

Tiemann, M., 1999, Leaking Underground Storage Tank Issues. CRS Report: 97-471.

,

USEPA(a), downloaded 6/29/08. Summary of the Resource Conservation and Recovery Act.

http://www.epa.gov/lawregs/laws/rcra.htm

USEPA(b), downloaded 6/29/08. Leaking Underground Storage Tank (LUST) Trust Fund.

http:www.epa.gov/oust/ltffacts.htm

USEPA(c), downloaded 6/29/08. CERCLA Overview.

http://www.superfund/policy/cercla.htm

USEPA(d) download 10/28/08, SARA Overview http://www.epa.gov/superfund/policy/sara.htm

U.S. General Accounting Office. Freshwater Supply: States' Views of House Federal Agencies

Could Help Them Meet the Challenges of Expected Shortages (GAO-03-514). July

2003, p. 1.

Watson, T.L. and Bachu, S., "Evaluation of the potential for gas and CO2 leakage along

wellbores," paper SPE 106817 presented at the 2007 E&P Environmental and Safety

Conference, Galveston, TX, March 5-7, 2007.

Wilson, M. and Monea, M., 2005, lEA GHG Weyburn Monitoring and Storage Project, Summary

Report, 2000-2004, Petroleum Technology Research Center, Regina SK, Canada,

Proceedings of the 7th International Conference on Greenhouse Gas Control

Technologies (GHGT-7), Vol. III, September 5-9, Vancouver, Canada

Wong, S., D. Keith, E. Wichert, W. Gunter1and T. McCann, 2003, Economics of Acid Gas

Reinjection: An Innovative CO2 Storage Opportunity. In Greenhouse Gas Control

Technologies, J. Gale and Y. Kaya (Eds.) © 2003 Elsevier Science Ltd. All rights

reserved

World Resources Institute, 2007, Workshop Summary: Addressing Long-Term Liability of

Carbon Dioxide Capture and Geologic Sequestration.

World Resources Institute, 2006, Executive Summary: WRI Workshop on CCS Liability.

25

g'fd'8\\'& w~ter aSSOCiation'

¢i d
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

__.. .... _~. _ ...._ .... _" ._.... _., o. . .. " --_._- ... _. -, _.... --_. _. _....-. ........._. Preamble Questions

Injection of C02 for the purposes of enhanced oil and gas The transition of carbon dioxide injection wells from Class II (Enhanced Oil

recovery (EORlEGR), as long as any production is Recovery wells) to Class VI (carbon sequestration wells) will presumably be

occurring, will continue to be permitted under the Class II requested when production of the petroleum has ceased. Liquid carbon dioxide

program. EPA seeks comment on the merits of this from a distant source, such as a power plant, can be stored in the depleted

approach since owners or operators of some Class II petroleum reservoir even after production has ceased, necessitating a change in

EOR/EGR wells may wish to use wells for the purposes of classification of the injection well. The new use of the wells involves much longer

production and GS prior to the field being completely storage time, and raises concerns about mechanical integrity and long tenm

depleted. EPA Notice 48. effects, including geochemical changes, on underground source of drinking water

(USDWs). The reclassification should depend on a positive outcome from a Class

V experimental program conducted in the depleted reservoir. See NGWA

Comment Document (word document) Section titled "Classification of Injection

Wells for Carbon Sequestration, Class II Injection Well Transition, and

Grandfathering" for further details.

EPA seeks comment on how the grandfathering approach See NGW Comment Document (word document) Section titled "Classification of

for existing wells may affect compliance with the other Injection Wells for Carbon Sequestration, Class II Injection Well Transition, and

requirements in its oroposal. EPA Notice 50. Grandfatherino" for further details.

The location and proximity of other formations to USDWs NGWA supports the general prohibition against injections above the lowermost

may preclude their use for GS. EPA seeks comment on USDW. An exemption process should be available to review and consider those

prohibiting injection into such formations if they are above specific situations where injection cannot be done, or is being proposed not to be

the lowermost USDW. EPA Notice 54. done, below the lowermost USDW

December 12, 2008 1
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551,7379, ext. 560. creimer@lnqwa.orq

EPA's proposal would provide the Director the discretion to While NGWA beiieves that a site with a single confining can provide storage

require the owner or operator to identify and characterize integrity, NGWA recommends that if there are additional confining iayers at the

additionai confining and containment zones above the site they should be characterized to get a better estimate of leakage risk to

primary (I.e., iowermost) confining zone that could further USDWs and possibly identify additional monitoring zones.

impede verticai fluid movement and allow for pressure

dissipation. EPA says that these layers could provide

additionai sites for monitoring, mitigation, and remediation.

EPA's proposai would not require that these additional

zones be identified for all GS sites because their absence

does not necessarily indicate inappropriateness of a GS

site. However, if such zones are present, information about

their characteristics can provide inputs for predictive

models, identify appropriate monitoring iocations, and

improve pubiic confidence in and acceptance of a proposed

GS site. EPA specificaiiy seeks comment on the merits of

requiring the identification of these additional zones. EPA

Notice 64.

In some cases, owners or operators may choose to use

proprietary models (I.e., not avaiiable for free to the generai

pubiic). EPA says it is aware that the use of proprietary

codes may prevent fuii evaluation of model results (e.g.,

NRC, 2007). Several popuiar codes in the petroieumreservoir engineering discipiine are proprietary and owners

or operators of particular sites may prefer to use these

codes as they have previous experience with them, and

they have been used in peer-reviewed studies to model

C02 sequestration. When using a proprietary modei,

owners or operators should clearly disclose the code

assumptions, relevant equations, and scientific basis. EPA

seeks comment on allowing the use of proprietary models

for GS sites. EPA Notice 68.

EPA seeks comment on the applicabiiity of computational

fluid flow models for deiineating the AoR of GS sites. EPA

Notice 69.

December 12,2008

Yes, use of commercial proprietary codes should be authorized. Proprietary

doesn't mean secret. A proprietary code largely vetted by the industry can be the

best appiication in many circumstances. To promote peer review and

benchmarking, the assumptions and theories for all numerical models should be

pubiicly available and the solution of any analytic equations used in the predictive

process should be fUlly elaborated.

See NGWA General Comment Document Section titled "General Comments on

Use of Modeiing for Ground-Water Protection Related to C02 Sequestration".

2
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water AssocIation, 601 Dempsey Rd, WestervIlle, OH 43081

'-'.... ,J~<;;l..... ......."'I..:;>~"'.... ,'\....II" .... " , ........ ww,,,, ...,""v.v..." .• '"',..." ........... VVV......, ..... "" .... , ........ " WH.........'

EPA seeks comment on requiring the reevaluation of the Yes, reevaluation is needed and at a higher frequency than 10 years, particularly

site AoR on a periodic basis, under what conditions the AoR at the beginning.

should be reevaluated, and the appropriateness of a 10-

year minimum fixed frequency for AoR reevaluation. EPA

Notice 72.

EPA proposes to allow a phased approach to corrective Yes, phased corrective action is a good idea. It wIll allow targeting of those wells

action but says this may not be appropriate in all situations; most in need of corrective action and optimize financIal resources as the

therefore EPA is proposing that the Director have the pressure/C02 plume may deviate from the initial AoR. That's why it is important to

discretion to decide to allow this approach, based on the review AoR more often than 10 years.

understanding of relevant geologic and site conditions. 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. EPA Notice 74.

EPA is soliciting comment on whether C02 injection should NGWA supports the general prohibition against injections above the lowermost

be allowed into an injection zone above the lowermost USDW. An exemption process should be available to review and consider those

USDW, when the Director determines that geologic specific situations where injection cannot be done, or is being proposed not to be

conditions (e.g., thousands of feet of intervening formations done, below the lowermost USDW

between the injection zone and the overlying and/or

underlying USDWs) exist that wIll prevent fluid movement

into adjacent USDWs. EPA Notice 93.

December 12,2008 3
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer~ilnawa.ora

Proposed Rule Revision or Comment Rationale

§144.1 Purpose and scope of part 144.

(1)(1 )(viii) Subpart H of this part sets forth

requirements for owners or operators of Class VI

injection wells.

(g) Scope ofthe permit or rule requirement. The UIC

Permit Program regulates underground injections by

six classes of wells (see definition of "well injection,"

§144.3). The six classes of wells are set forth in

§144.6. All owners or operators of these injection

wells must be authorized either by permit or rule by

the Director.

§144.6 Classification of wells.

(e) Class V. Injection wells not included in Class I, II,

111, IV, or VI. Specific types of Class V injection wells

are described in §144.81.

(I) Class VI. Wells used for geologic sequestration of Comment: NGWA supports the general prohibition against NGWA understands that there may be

carbon dioxide beneath the lowermost formation injections above the lowermost USDW. An exemption portions of the country that will not have

containing a USDW. process should be made available to review and consider adequate storage zones below the

those specific situations where injection cannot be done, or is lowermost USDW. In these areas, the

being proposed not to be done, below the lowermost USDW. Association believes that storage above the

lowermost USDW may be allowed on a site

specific basis based on director discretion

assuming that all other conditions are met.

Subpart B -General Program Requirements

§144.15 Prohibition of non-experimental Class V

wells for QeoloQic sequestration.

The construction, operation or maintenance of any

non-experimental Class V geologic sequestration

well is prohibited.

5. Adding Section 144.18 to read as follows.

§144.18 Requirements for Class VI wells.

December 12,2008

1
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

Nationa[ Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800,551,7379, ext 560, creimer ilnowa,oro

ProDosed Rule Revision or Comment Rationale

Owners or operators of Class VI wells must obtain a

permit Class VI wells are not authorized by rule to

inject

Subpart D-Authorization by Permit

§144.36 Duration of permits.

(a) Permits for Class I and V wells shall be effective Comment: Would there be a scenario where a facility would

for a fixed term not to exceed 10 years, UIC Permits stop and restart? Concern is to make sure temporarily

for Class II, III and V[ wells shall be issued for a stopped injection activity does not allow party to wait a period

period up to the operating life of the facility, of time and then walk away or alternatively cause closure if

only a temporary stop,

7, Section 144.39 is amended by revising the second

sentence in paragraph (a) introductory text and by

revising the second sentence in paragraph (a)(3)

introductory text to read as follows:

§144.39 Modification or revocation and

reissuance of oermits.

(a) For Class I hazardous waste injection wells,

Class II, Class III or Class VI wells the following may

be causes for revocation and reissuance as well as

modification: and for all other wells the following may

be cause for revocation or reissuance as well as

modification when the permittee requests or agrees.

(3) Permits other than for Class I hazardous waste

injection wells, Class II, Class [II or Class VI wells

may be modified during their terms for this cause

only as follows:

December 12, 2008

2
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer ilnqwa.orq

ProDosed Rule Revision or Comment Rationale

Subpart E-Permit Conditions

Section 144.51 is amended by revising the first

sentence in paragraph (q)(1) and the first sentence

in paragraph (q)(2) to read as:

§144.51 Conditions applicable to all permits.

(q) (1) The owner or operator ofa Class I, II, III orVI

well permitted under this part shall establish

mechanical integrity prior to commencing injection or

on a schedule determined by the Director. Thereafter

the owner or operator of Class I, II, and III wells must

maintain mechanical integrity as defined in §146.8

and the owner or operator of Class VI wells must

maintain mechanical integrity as defined in §146.89

of this chapter.

(2) When the Director determines that a Class I, II, III

or VI well lacks mechanical integrity pursuant to

§146.8 or §146.89 for Class VI of this chapter,

he/she shall give written notice of his/her

determination to the owner or operator.

9. Section 144.52 is amended by revising paragraph

(a)(8) to read as follows:

§144.52 Establishing permit conditions.

(a)(8) Mechanical integrity. A permit for any Class I,

II, III or VI well or injection project which lacks

mechanical integrity shall include, and for any Class

V well may include, a condition prohibiting injection

operations until the permittee shows to the

satisfaction of the Director under §146.08 or§146.89

for Class VI that the well has mechanical integrity.

10. Section 144.55 is amended by revising the first

sentence in paragraph (a) to read as follows:

December 12, 2008

3
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800,551,7379, ext 560, creimer 'ilnawaora

ProDosed Rule Revision or Comment Rationale

§144.55 Corrective Action.

(a) Coverage, Applicants for Class I, II, (other than Proposed Revision: (a) Coverage, Applicants for Class I, II, Concem about the use of the term known

existing), III or VI injection well permits shall identify (other than existing), III or VI injection well permits shall wells, Public records search may not be

the location of all known wells within the injection identify the location of all known wells within the injection adequate for older oil and gas wells, for

well's area of review which penetrate the injection well's area of review which penetrate the injection zone, or in example, Some language should be added

zone, or in the case of Class II wells operating over the case of Class II wells operating over the fracture pressure so that A more proactive approach is used,

the fracture pressure of the injection formation. all of the injection formation, all known wells within the area of e.g. physically walk site or do aerial review,

known wells within the area of review penetrating review penetrating formations affected by the increase in

formations affected by the increase in pressure, pressure, Applicants for Class VI shall perform mapping with

Applicants for Class VI shall perform corrective sufficient resolution as to make a comprehensive effort to

action as specified in §146,84, identify wells that are not in the public record using aerial

photography, aerial survey, or other methods acceptable to

the director corrective action as specified in §146,84 if needed

Subpart G-Requirements for Owners and

Ooerators of Class V Iniection Wells

11. Section 144,80 is amended by revising the first

sentence in paragraph (e) and by adding paragraph

(1) to read as follows:

§144.80 What is a Class V injection well?

(e) Class V, Injection wells not included in Class I, II,

1I1,IVorVL

(1) Class VI, Wells used for geologic sequestration of

carbon dioxide,

PART 146-UNDERGROUND INJECTION

CONTROL PROGRAM: CRITERIA AND

STANDARDS

§146,5 Classification of injection wells.

(e) Class V, Injection wells not included in Class I, II,

1I1.IVorVL

December 12, 2008

4
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer 'Vnawa.ora

ProDosed Rule Revision or Comment Rationale

(I) Class VI. Wells used for geologic sequestration of

carbon dioxide beneath the lowermost formation

containing an underground source of drinking water

(USDW).

Subpart H-Criteria and Standards Applicable to

Class VI Wells

§146.81 Applicability.

(a) This subpart establishes criteria and standards

for underground injection control programs to

regulate Class VI carbon dioxide geologic

sequestration injection wells.

(b) This SUbpart applies to wells used to inject Comment: NGWA supports the use of Class VI as

carbon dioxide specifically for the purpose of "specifically for geologic carbon sequestration and believes

geologic sequestration, i.e., the iong-term that EOR and GS shouid be sequential and not concurrent"

containment of a gaseous, liquid or supercritical

carbon dioxide stream in subsurface geologic

formations.

(c) This subpart applies to owners and operators of

permit or ruie-authorized Class I industrial, Class II.

or Ciass V experimental carbon dioxide injection

projects who seek to apply for a Class VI geoiogic

sequestration permit for their well or wells. If the

Director determines that USDWs will not be

endangered, such wells are exempt, at the Director's

discretion, from the casing and cementing

requirements at §§146.86(b) and 146.87(a)(1)

through (3).

(d) Definitions. The following definitions apply to this

subpart. To the extent that these definitions confiict

with those in §146.3 these definitions govern:

December 12, 2008

5
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer~i2nawa.ora

ProDosed Rule Revision or Comment Rationale

Area ofreview means the region surrounding the Proposed Revision: Area ofreview means the region The AOR needs to be based on both the

geologic sequestration project that may be impacted surrounding the geologic sequestration project that may be C02 plume and the associated pressure

by the injection activity. The area of review is based impacted by the injection activity. The area of review is based front in order to completely identify the areas

on computational modeling that accounts for the on computational modeling that accounts for the physical and that may be affected by the injection

physical and chemical properties of all phases of the chemical properties of all phases of the injected carbon

injected carbon dioxide stream. dioxide stream and the zone of increased pressure created by

the injection.

Carbon dioxide plume means the underground

extent, in three dimensions, of an injected carbon

dioxide stream.

Carbon dioxide stream means carbon dioxide that

has been captured from an emission source (e.g., a

power plant), plus incidental associated substances

derived from the source materials and the capture

process, and any substances added to the stream to

enable or improve the injection process. This subpart

does not apply to any carbon dioxide stream that

meets the definition of a hazardous waste under 40

CFR part 261.

Confining zone means a geologic formation, group

of formations, or part of a formation stratigraphically

overlying the injection zone that acts as a barrier to

fluid movement.

Corrective action means the use of Director

approved methods to assure that wells within the

area of review do not serve as conduits for the

movement of fluids into underground sources of

drinking water (USDW).

December 12, 2008

6
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer 'i2nowa.ora

ProDosed Rule Revision or Comment Rationale

Geologic sequestration means the long-term

containment of a gaseous, liquid or supercritical

carbon dioxide stream in subsurface geologic

formations. This term does not apply to its capture or

transport.

Geologic sequestration project means an injection Proposed Revision: Geologic sequestration project means an See Section 144.6(1). If an exemption is

well or wells used to emplace a carbon dioxide injection well or wells used to emplace a carbon dioxide provided, USDWs below the C02 plume or

stream beneath the lowermost formation containing stream. It includes the subsurface three-dimensional extent of pressure front should be included in the AOR

a USDW. It includes the subsurface three- the carbon dioxide plume, associated pressure front, and specifically.

dimensional extent of the carbon dioxide plume, displaced brine, as well as all USDWs and the surface area

associated pressure front, and displaced brine, as above that delineated region.

well as the surface area above that delineated

region.

Injection zone means a geologic formation, group of

formations, or part of a formation that is of sufficient

areal extent, thickness, porosity, and permeability to

receive carbon dioxide through a well or wells

associated with a geologic sequestration project.

Post-injection site care means appropriate

monitoring and other actions (inclUding corrective

action) needed following cessation of injection to

assure that USDWs are not endangered as required

under §146.93.

Pressure front means the zone of elevated pressure

that is created by the injection of carbon dioxide into

the subsurface. For the purposes of this subpart, the

pressure front of a carbon dioxide plume refers to a

zone where there is a pressure differential sufficient

to cause the movement of injected fiuids or formation

fiuids into a USDW.

December 12, 2008

7
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer j)nqwa.ora

ProDosed Rule Revision or Comment Rationale

Site closure the pointftime, as determined by the

Director following the requirements under §146.93,

at which the owner or operator of a GS site is

released from post-injection site care responsibilities.

Transmissive fault or fracture means a fault or

fracture that has sufficient permeability and vertical

extent to allow fluids to move between formations.

§146.82 Required Class VI permit information.

This section sets forth the information which the Comment: NGWA raises the question of whether a

owner or operator must submit to the Director in requirement should be included that all applications for Class

order to be permitted as a Class VI well. The VI construction permits include a certification that the facility

application for a permit for construction and was designed by an appropriately qualified professional

operation of a Class VI well must include the engineer with an option for an appropriate qualified

following: professional geologist to certify the well design (taking into

consideration confinement, injectivity, etc).

Proposed addition: (1) Class VI - Test/Injection Well

Construction and Testing Permit

Proposed addition: (a) The Director shall deny a construction

permit if construction of the well itself may endanger the

health of persons or the environment

Proposed addition: (b) For construction permit approval,

reasonable assurance is required that the project will function

in compliance with this chapter. The Director shall require an

exploratory well for those projects located in an area where

available information is lacking conceming geologic or

hydraulic confinement or existing information indicates that

geologic or hydraulic confinement may be poor or lacking.

Proposed addition: (c) For a Class VI well, issuance of a

construction permit does not obligate the Director to authorize

any operation of the well, unless reasonable assurance has

been provided that the well can operate in compliance with

this chapter.

December 12, 2008

8
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer 'ilnawa.ora

ProDosed Rule Revision or Comment Rationale

Proposed addition: (d) Information required in 40 CFR 144.31

(e)(1) through (6)

Proposed addition: (e) A map showing the injection well(s) for

which a permit is sought and the applicable area of review.

Within the area of review, the map must show the number, or

name and location of all injection wells, producing wells,

abandoned wells, plugged wells or dry holes, deep

stratigraphic boreholes, State or EPA approved subsurface

cleanup sites, surface bodies of water, springs, mines

(surface and subsurface), quarries, water wells and other

pertinent surface features including structures intended for

human occupancy and roads. The map should also show

faults, if known or suspected. Only information of public

record is required to be included on this map;

Proposed addition: (f) The area of review based on modeling,

using data obtained during logging and testing of the well and

the formation as required by paragraphs (I), (r), and (s) of this

section;

Proposed addition: (g) Information on the geologic structure

and hydrogeologic properties of the proposed storage site and

overlying formations, including

Proposed addition: (1) Maps and cross sections of the area of

review;

Proposed addition: (2) Location, orientation, and properties of

known or suspected faults and fractures that may transect the

confining zone(s) in the area of review and a determination

that they would not interfere with containment:

Proposed addition: (3) Information on seismic history including

the presence and depth of seismic sources and a

determination that the seismicity would not interfere with

containment:

December 12, 2008

9
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer J>-nqwa.orq

Prooosed Rule Revision or Comment Rationale

Proposed addition: (4) Data on the depth, areal extent:

thickness, mineralogy, porosity, permeability and capillary

pressure of the injection and confining zone(s); including

geology/facies changes based on field data which may

inciude geologic cores, outcrop data, seismic surveys, well

logs, and names and lithologic descriptions;

Proposed addition: (5) Geomechanical information on

fractures, stress, ductility, rock strength, and in situ fiuid

pressures within the confining zone; and

Proposed addition: (6) Geologic and topographic maps and

cross sections illustrating regional geology, hydrogeology, and

the geologic structure of the local area

Proposed addition: (h) All wells within the AOR and whose A substantive risk analysis can be

total depth is greater than the depth to the bottom of the performed only if all the (known) wells within

lowermost USDW should be compiled. However, preventive the AOR and between the injection formation

corrective action should be undertaken only for those wells and the bottom of the USDW are described.

that penetrate the injection and confining zone(s)

Proposed addition: (i) Maps and stratigraphic cross sections

indicating the general vertical and laterai limits of all USDWs,

water wells and springs within the area of review, their

positions relative to the injection zone(s) and the direction of

water movement, where known;

Proposed addition: Q) Baseline geochemical data on

subsurface formations, including all USDWs in the area of

review;

Proposed addition: (k) Proposed operating data:

Proposed addition: (1) Average and maximum daily rate and

voiume of the carbon dioxide stream;

Proposed addition: (2) Average and maximum injection

pressure;

Proposed addition: (3) The source ofthe carbon dioxide

stream; and

Proposed addition: (4) An analysis of the chemicai and

physical characteristics of the carbon dioxide stream;

December 12,2008

10
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Weiis, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer 'llnqwa.orq

Proposed Rule Revision or Comment Rationale

Proposed addition: (I) The compatibility ofthe carbon dioxide

stream with fluids in the injection zone and minerals in both

the injection and the confining zone(s), based on the results of

the formation testing program, and with the materials used to

construct the well;

Proposed addition: (m) Proposed formation testing program to

obtain an analysis of the chemical and physical characteristics

of the injection zone and confining zone;

Proposed addition: (n) Proposed stimulation program and a

determination that stimulation will not interfere with

containment;

Proposed addition: (0) Proposed formation testing program to

obtain an analysis of the chemical, physical and radiological

characteristics of and other information on the injection zone.

Proposed addition: (p) Proposed procedure to outline steps

necessary to conduct injection operation;

Proposed addition: (q) Engineering drawings of the surface

and subsurface construction details olthe system, including

design features for surge control and water hammer

protection:

Proposed addition: (r) Injection well construction procedures

that meet the requirements of Section 146.86;

Proposed addition: (s) Proposed area of review and corrective

action plan that meets the requirements under Section

146.84;

Proposed addition: (t) The status of corrective action on wells

in the area of review;

Proposed addition: (u) A demonstration, satisfactory to the

Director, that the applicant has met the financial responsibility

requirements under Section 146.85;

Proposed addition: (v) Proposed testing and monitoring plan

required by Section 146.90

Proposed addition: (w) Proposed injection well plugging plan

required by Section 146.92(b)

December 12, 2008

11
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer ilnowa.ora

ProDosed Rule Revision or Comment Rationale

Proposed addition; (x) Proposed post-injection site care and

site closure plan required by Section 146.93(a)

Proposed addition: (y) Proposed emergency and remedial

response plan required by Section 146.94; and

Proposed addition; (z) Any other information requested by the

Director.

Proposed addition; (2) Required Class VI operation permit

information

(a) Information required in 40 CFR 144.31 (e)(1) Renumber 2(a)

through (6);

(b) A map showing the injection well(s) for which a Renumber 2(b)

permit is sought and the applicable area of review.

Within the area of review, the map must show the

number, or name and location of all injection wells,

producing wells, abandoned wells, plugged wells or

dry holes, deep stratigraphic boreholes, State or

EPA approved subsurface cleanup sites, surface

bodies of water, springs, mines (surface and

subsurface), quarries, water wells and other pertinent

surface features including structures intended for

human occupancy and roads. The map should also

show faults, if known or suspected. Only information

of public record is required to be included on this

map;

December 12, 2008

12
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer 'ilnowa.ora

ProDosed Rule Revision or Comment Rationale

(c) The area ofreview based on modeling, using Proposed Revision: 2(c) Re-evaluation of Area of Review.

data obtained during logging and testing of the well After completion of the operational testing period, the Area of

and the formation as required by paragraphs (I), (r), Review shall be re-evaluated, using a calibrated, multi-phase

and (s) of this section; fluid flow model. The data collection during operational

testing must be adequate for calibration of the model. If a

calibrated model cannot be prepared using data collected

during operational testing, the owner or operator shall apply

for a new period of operational testing of up to two years in

order to collect the required data.

(d) Information on the geologic structure and Renumber 2(d)

hydrogeologic properties of the proposed storage

site and overlying formations, including:

(1) Maps and cross sections of the area of review;

(2) Location, orientation, and properties of known or

suspected faults and fractures that may transect the

confining zone(s) in the area of review and a

determination that they would not interfere with

containment;

(3) Information on seismic history including the

presence and depth of seismic sources and a

determination that the seismicity would not interfere

with containment;

(4) Data on the depth, areal extent, thickness,

mineralogy, porosity, permeability and capillary

pressure of the injection and confining zone(s);

including geology/facies changes based on field data

which may include geOlogic cores, outcrop data,

seismic surveys, well logs, and names and lithologic

descriptions;

(5) Geomechanical information on fractures, stress,

ductility, rock strength, and in situ fluid pressures

within the confining zone; and

December 12, 2008

13
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer6 'Unowa.ora

ProDosed Rule Revision or Comment Rationale

(6) Geologic and topographic maps and cross

sections illustrating regional geology, hydrogeology,

and the geologic structure of the local area.

(e) A tabulation of all wells within the area of review Renumber 2(e)

which penetrate the injection or confining zone(s).

Such data must include a description of each well's

type, construction, date drilled, location, depth,

record of plugging andlor completion, and any

additional information the Director may require;

(f) Maps and stratigraphic cross sections indicating Renumber 2(f)

the general vertical and lateral limits of all USDWs,

water wells and springs within the area of review,

their positions relative to the injection zone(s) and

the direction of water movement, where known;

(g) Baseline geochemical data on subsurface Renumber 2(g)

formations, including all USDWs in the area of

review;

(h) Proposed operating data: Renumber 2(h)

(1) Average and maximum daily rate and volume of

the carbon dioxide stream;

(2) Average and maximum injection pressure;

(3) The source of the carbon dioxide stream; and

(4) An analysis of the chemical and physical

characteristics of the carbon dioxide stream;

Proposed addition: (5) Contingency plans to cope with all shut

ins or well failures, including emergency discharge provisions;

December 12, 2008

14
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer ilnawa.ora

ProDosed Rule Revision or Comment Rationale

(0 The compatibility of the carbon dioxide stream Renumber 2(0

with fluids in the injection zone and minerals in both

the injection and the confining zone(s), based on the

results of the fonmation testing program, and with the

materials used to construct the well;

0) Proposed fonmation testing program to obtain an Proposed revision: 20) Results of the formation testing

analysis of the chemical and physical characteristics program to obtain an analysis of the chemicai, physical and

of the injection zone and confining zone; radioiogical characteristics of and other information on the

injection zone.

(k) Proposed stimulation program and a Renumber 2(k)

detenmination that stimulation will not interfere with

containment;

(I) The resuits of the formation testing program as Renumber 2(i)

required in paragraph 0) of this section;

(m) Proposed procedure to outline steps necessary Renumber 2(m)

to conduct injection operation;

(n) Schematic or other appropriate drawings of the Proposed revision: 2 (n) Engineering drawings olthe surface

surface and subsurface construction details of the and subsurface construction details of the system, including

well; design features for surge controi and water hammer

protection, including the following:

Proposed addition: (1) Record drawings, based upon

inspections by the engineer of record or persons under his

direct supervision, with all deviations noted;

Proposed addition: (2) Copies of the mill certificates of all

casings used in the construction of the well;

Proposed addition: (3) Certification of completion submitted by

the engineer of record;

Proposed addition: (4) An operation manual including

emergency procedures;

Proposed addition: (5) Proposed monitoring program and data

to be SUbmitted;

December 12, 2008

15
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800,551,7379, ext. 560, creimer ilnqwa,orq

Proposed Rule Revision or Comment Rationale

Proposed addition: (6) Proof that the existence of the well and

any associated monitoring wells have been recorded with the

permanent warranty deed or other instrument of conveyance

as a two page proviso or addendum that contains certification

of the locations of the wells (by metes and bounds) and a

detailed sketch of the parcel that shows the location of the

well. The location shall be measured by a certified land

surveyor, and shall contain the surveyor's signature,

registration number, official seal, and the following statement:

"1 hereby certify that this survey was made under my

responsible direction and supervision, and is a correct

representation of the land surveyed,"

(0) Injection well construction procedures that meet Renumber 2(0)

the requirements of §146,86;

(p) Proposed area of review and corrective action Renumber 2(p)

plan that meets the requirements under §146,84;

(q) The status of corrective action on wells in the Renumber 2(q)

area of review;

(r) All available logging and testing program data on Renumber 2(r )

the well required by §146,87;

(s) A demonstration of mechanical integrity pursuant Renumber 2(s)

to §146,89;

(t) A demonstration, satisfactory to the Director, that Renumber 2(t)

the applicant has met the financial responsibility

requirements under §146,85;

(u) Proposed testing and monitoring plan required by Renumber 2(u)

§146,90:

December 12, 2008

16
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer~j)nqwa.ora

ProDosed Rule Revision or Comment Rationale

(v) Proposed injection well plugging plan required by Renumber 2(v)

§146.92(b);

(w) Proposed post-injection site care and site closure Renumber 2(w)

plan required by §146.93(a);

(x) Proposed emergency and remedial response plan Renumber 2(x)

required by §146.94; and

(y) Any other information requested by the Director. Renumber 2(y)

Proposed addition: (3) Operational Testing

Proposed addition: (a) For Class VI wells, the construction

permit includes a period of temporary injection operation for

the purposes of long term testing. Prior to commencement of

operational testing:

Proposed addition: 1. Construction of the injection well shall

be complete and the permittee shall submit a notice of

completion of construction to the Director.

Proposed addition: 2. Each well shall first be tested for

integrity of construction, and shall be followed by a short term

injection test of such duration to allow for the prediction of the

operating pressure.

Proposed addition: 3. The permittee shall submit the following

information to the Director, as described in the permit.

Proposed addition: a. A copy of the borehole television

survey(s)

Proposed addition: b. Geophysical logs,

Proposed addition: c. Mechanical integrity test data,

Proposed addition: d. Data obtained during the short term

injection testing conducted according to subparagraph 2.

above.

Proposed addition: e. Confining zone data,

Proposed addition: f. Background water quality data for the

injection and monitor zones;

Proposed addition: g. Waste stream analysis,

December 12, 2008

17
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimerGilnawa.ora

ProDosed Rule Revision or Comment Rationale

Proposed addition: h. As-built well construction specifications,

and

Proposed addition: i. Other data obtained during well

construction which demonstrates that the well will operate in

compliance with this chapter.

Proposed addition: 4. Any corrective action required under

Section 146.84, shall be completed.

Proposed addition: 5. Prior to granting approvai for

operationai testing of a Class VI well, the Director shall

consider the fOllowing information:

Proposed addition: a. All available logging and testing

program data on the well:

Proposed addition: b. A demonstration of mechanical integrity

Proposed addition: c. The anticipated maximum pressure and

fiow rate at which the permittee wiil operate:

Proposed addition: d. The results of the formation testing

program;

Proposed addition: e. The actuai injection procedure;

Proposed addition: f. The compatibility of injected waste with

fiuids in the injection zone and minerals in both the injection

zone and the confining zone;

Proposed addition: g. The status of corrective action on

defective wells in the area of review; and

Proposed addition: (b) Written authorization for operational

testing shall be obtained from the Director. Authorization shall

be for up to two years or the expiration date of the

construction permit, whichever is less, and is only renewable

once as described in Section 146.91. The authorization shall

specify the conditions under which operational testing is

approved. The authorization shall include:

Proposed addition: 1. Injection pressure limitation,

Proposed addition: 2. Injection fiow rate limitation,

Proposed addition: 3. injection well monitoring requirements,

Proposed addition: 4. Effluent monitoring requirements,

December 12, 2008

18
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer ilnowa.ora

Proposed Rule Revision or Comment Rationale

Proposed addition: 5. Weekly ground water sampling of

monitor wells,

Proposed addition: 6. Monthly specific injectivity testing,

Proposed addition: 7. Reporting requirements, and

Proposed addition: 8. An expiration date for the operational

testing period not to exceed two years.

Proposed addition: (c) Before authorizing operational testing,

the Director shall conduct an inspection of the facility to

determine if the conditions of the permit have been met.

Proposed addition: (d) A sampling frequency and reporting of

less than once per month shall not be allowed.

Proposed addition: (e) For Class VI wells, the duration of the

operational testing period shall not exceed two years or the

expiration date of the construction permit, whichever is less. If

the Director has not issued an intent to issue an operation

permit for the einjectionwell9s) by the end of the operational

testing period, the permittee shall cease injection.

Proposed addition: (I) For a Class VI well, if an operation

permit has not been obtained for the well within two years

after the cessation of operational testing, the permittee shall

submit an application to the Director to plug and abandon the

well in accordance with Section 146.92.

Proposed addition: (4) The Director shall conduct periodic

inspections during construction

§146.83 Minimum criteria for siting.

(a) Owners or operators of Class VI wells must

demonstrate to the satisfaction of the Director that

the wells will be sited in areas with a suitable

geologic system. The geologic system must be

comprised of:

December 12, 2008

19
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimerl<ilnowa.ora

ProDosed Rule Revision or Comment Rationale

(1) An injection zone of sufficient areal extent,

thickness, porosity, and permeability to receive the

total anticipated volume of the carbon dioxide

stream;

(2) A confining zone(s) that is free of transmissive

faults or fractures and of sufficient areal extent and

integrity to contain the injected carbon dioxide

stream and dispiaced formation fluids and allow

injection at proposed maximum pressures and

volumes without initiating or propagating fractures in

the confining zone(s); and

(b) At the Director's discretion, owners or operators Proposed revision: (b) Owners or operators of Class VI wells While NGWA believes that a site with a

of Ciass VI wells must identify and characterize must identify and characterize additional zones, if they exist, singie confining can provide storage integrity

additional zones that will impede vertical fluid that will impede vertical fluid movement, allow for pressure we feel that if there are additional confining

movement, are free of faults and fractures that may dissipation, and provide additionai opportunities for iayers at the site they should be

interfere with containment, allow for pressure monitoring, mitigation and remediation. Vertical faults and characterized to get a better estimate of

dissipation, and provide addilionai opportunities for fractures that transect these zones must be identified. leakage risk to USDWs and possibly identify

monitoring, mitigation and remediation. additional monitoring zones.

§146.84 Area of review and corrective action.

(a) The area of review is the region surrounding the

geologic sequestration project that may be impacted

by the injection activity. The area of review is based

on computational modeling that accounts for the

physicai and chemical properties of all phases of the

injected carbon dioxide stream.

December 12, 2008

20
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, WesteNiIIe, OH 43081

Contact Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer 'i)nqwa.orq

ProDosed Rule Revision or Comment Rationale

(b) The owner or operator of a Class VI well must

prepare, maintain, and comply with a plan to

delineate the area of review for a proposed geologic

sequestration project, periodically reevaluate the

delineation, and perform corrective action that meets

the requirements of this section and is acceptable to

the Director. As a part of the permit application for

approval by the Director, the owner or operator must

submit an area of review and corrective action plan

that includes the following information:

(1) The method for delineating the area of review that

meets the requirements of paragraph (c) of this

section, including the model to be used, assumptions

that will be made, and the site characterization data

on which the model will be based;

(2) A description of:

(i) The minimum fixed frequency, not to exceed 10 Proposed revision: (i) The owner or operator will reevaluate NGWA believes that a frequency of every 10

years, the owner or operator proposes to reevaluate the AOR after two yearsof operational testing (prior to years is too long to identify early

the area of review; issuance of the operating permit), and after 5 years and then discrepancies between the site performance

no less frequently than every 5 years for the life of the project; and the site model. Seeing early difference

will allow for earlier model updating and

provide additional reduction in leakage risk.

(Ii) The monitoring and operational conditions that

would warrant a reevaluation of the area of review

prior to the next scheduled reevaluation as

determined by the minimum fixed frequency

established in paragraph (b)(2)(Q of this section.

(iii) How monitoring and operational data (e.g.,

injection rate and pressure) will be used to inform an

area of review reevaluation; and

December 12, 2008

21
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer 2lnawa.ora

ProDosed Rule Revision or Comment Rationale

(iv) How corrective action will be conducted to meet

the requirements of paragraph (d) of this section,

including what corrective action wiil be performed

prior to injection and what, if any, portions of the area

of review will have corrective action addressed on a

phased basis and how the phasing will be

determined: how corrective action will be adjusted if

there are changes in the area of review; and how site

access will be guaranteed for future corrective

action.

(c) Owners or operators of Class VI wells must Comment: There should be somewhere in the rules a

perform the following actions to delineate the area of requirement that "mutual interference effects" should trigger

review, identify all wells that require corrective action, reevaluation and re-delineation of the AORs of ail projects that

and perform corrective action on those wells: are interferring with each other. In essence, when a new

project is submitted for permitting, there should be a systemwide, "regional" entity charged with ensuring that AORs for

each project are appropriate, and perhaps that a "hybrid" or

"combo AOR" be defined for the set of mutually-interferring

projects.

(1) Predict, using computational modeling, the

projected lateral and vertical migration of the carbon

dioxide plume and formation fluids in the subsurface

from the commencement of injection activities until

the plume movement ceases, pressure differentials

sufficient to cause the movement of injected fluids or

formation fluids into a USDW are no longer present,

or after a fixed time period as determined by the

Director. The model must:

(i) Be based on detailed geologic data coilected to Proposed revision: (i) Be based on detailed geologic data NGWA proposes that if there are secondary

characterize the injection zone, confining zone and collected to characterize the injection zone, confining zone(s), conflning units that they should be included

any additional zones; and anticipated operating data, transmissive monitoring zones and any additional zones; and in the site model along with any transmissive

including injection pressures, rates and total volumes anticipated operating data, including injection pressures, rates zones between the primary and secondary

over the proposed life of the geological sequestration and total volumes over the proposed life of the geological confining units.

project; sequestration project;

December 12, 2008

22
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800,551,7379, ext 560, creimer 1'il.nawa,orn

Proposed Rule Revision or Comment Rationale

(iO Take into account any geologic heterogeneities,

data quality, and their possible impact on model

predictions: and

(iii) Consider potential migration through faults,

fractures, and artificial penetrations,

(2) Using methods approved by the Director, identify Proposed revision: (2) Using methods approved by the This makes this consistent with NGWA's

all penetrations, including active and abandoned Director, identify all penetrations, inclUding active and proposed section 146(a)(8)

wells and underground mines, in the area of review abandoned wells and underground mines, in the area whose

that may penetrate the confining zone, Provide a total depth is greater than the depth to the bottom of the

description of each well's type, construction, date lowermost USDW, including those penetrating the confining

drilled, location, depth, record of plugging andlor zone, Provide a description of each well's type, construction,

completion, and any additional information the date drilled, location, depth, record of plugging andlor

Director may require; and completion, and any additional information the Director may

require; and

(3) Determine which abandoned wells in the area of

review have been plugged (as required by §146,92)

in a manner that prevents the movement of carbon

dioxide or associated fiuids that may endanger

USDWs,

(d) Owners or operators of Ciass VI wells must ,

perform corrective action on all wells in the area of

review that are determined to need corrective action

using methods necessary to prevent the movement

of fiuid into or between USDWs including use of

corrosion resistant materials, where appropriate,

(e) If monitoring data indicate an endangerment to

USDWs, the owner or operator must notify the

Director and cease operations as required by

§146,94,

December 12, 2008

23
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimerullnqwa.orq

Proposed Rule Revision or Comment Rationale

(I) At the minimum fixed frequency, not to exceed 10 Proposed revision: (I) At the minimum fixed frequency, not to This makes this consistent with NGWA's

years, as specified in the area of review and exceed two years if under operational testing (prior to proposed revision to Section 146.84(b)(2)(i)

corrective action plan, or when monitoring and issuance of the operating permit), or 5 years (if operating

operational conditions warrant, owners or operators permit has been issued), as specified in the area of review

must: and corrective action plan or when monitoring and operational

conditions warrant, owners or operators must:

(1) Reevaluate the area of review in the same

manner specified in paragraph (c)(1) of this section:

(2) Identify all wells in the reevaluated area of review

that require corrective action in the same manner

specified in paragraph (c)(2) of this section;

(3) Perform corrective action on wells requiring

corrective action in the reevaluated area of review in

the same manner specified in paragraph (c)(3) of this

section; and

(4) Submit an amended area of review and corrective

action plan or demonstrate to the Director through

monitoring data and modeling results that no

amendment to the area of review and corrective

action plan is needed.

(g) The emergency and remedial response plan (as

required by §146.94) and a demonstration of

financial responsibility (as described by §146.85)

must account for the entire area of review,

regardless of whether or not corrective action in the

area of review is phased.

§146.85 Financial responsibility.

December 12,2008

24
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Weiis, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerviiie, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer 'llnawa.ora

Proposed Rule Revision or Comment Rationale

(a) The owner or operator must demonstrate and Comment: A question was raised during discussions about

maintain financial responsibility and resources for how the producer of the C02 is impacted and whether they

corrective action (that meets the requirements of should maintain some liability.

§146.84), injection well plugging (that meets the

requirements of §146.92), post-injection site care

and site closure (that meets the requirements of

§146.93), and emergency and remedial response

(that meets the requirements of §146.94) in a

manner prescribed by the Director until:

(1) The Director receives and approves the

completed post-injection site care and site closure

plan; and

(2) The Director determines that the site has reached

the end of the post injection site care period.

(b) The owner or operator must provide to the Proposed revision: (b) The owner or operator must provide to NGWA proposes that potential changes in

Director, at a frequency determined by the Director, the Director, at the same frequency as the AOR reevaluation, the size of the AOR require that all site plans

written updates of adjustments to the cost estimate written updates of adjustments to the cost estimate to account be reevaluated at the same frequency as the

to account for any amendments to the area of review for any amendments to the area of review and corrective AOR.

and corrective action plan (§146.84), the injection action plan (§146.84), the injection well plugging plan

well plugging plan (§146.92), and the post-injection (§146.92), and the post-injection site care and site closure

site care and site closure plan (§146.93). plan (§146.93).

(c) The owner or operator must notify the Director of

adverse financial conditions such as bankruptcy, that

may affect the ability to carry out injection well

piugging and post-injection site care and site

closure.

December 12, 2008

25
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer j)nqwa.orq

Proposed Rule Revision or Comment Rationale

(d) The operator must provide an adjustment of the

cost estimate to the Director if the Director has

reason to believe that the original demonstration is

no longer adequate to cover the cost of injection well

plugging (as required by §146.92) and post-injection

site care and site closure (as required by §146.93).

§146.86 Injection well construction requirements.

(a) General. The owner or operator must ensure that

all Class VI wells are constructed and completed to:

(1) Prevent the movement of fluids into or between

USDWs or into any unauthorized zones:

(2) Permit the use of appropriate testing devices and

work over tools; and

(3) Permit continuous monitoring of the annulus Comment: NGWA supports this provision

space between the injection tubing and long string

casing.

(b) Casing and Cementing ofClass VI Wells.

December 12, 2008

26
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer ilnawa.ora

ProDosed Rule Revision or Comment Rationale

(1) Casing and cement or other materials used in the Comment NGWA supports this provision

construction of each Class VI well must have

sufficient structural strength and be designed for the

life of the geologic sequestration project. All well

materials must be compatible with fluids with which

the materiais may be expected to come into contact

and meet or exceed standards developed for such

materials by the American Petroleum Institute, ASTM

International, or comparable standards acceptable to

the Director. The casing and cementing program

must be designed to prevent the movement of fluids

into or between USDWs. In order to allow the

Director to determine and specify casing and

cementing requirements, the owner or operator must

provide the following information:

(i) Depth to the injection zone;

(ii) Injection pressure, external pressure, internal

pressure and axial loading;

(iii) Hole size;

(iv) Size and grade of all casing strings (wall

thickness, external diameter, nominal weight, length,

joint specification and construction material);

(v) Corrosiveness of the carbon dioxide stream, and

formation fluids;

(vi) Down-hole temperatures;

(vii) Lithology of injection and confining zones;

(viii) Type or grade of cement; and

(ix) Quantity, chemical composition, and temperature

of the carbon dioxide stream.

(2) Surface casing must extend through the base of

the lowermost USDW and be cemented to the

surface.

December 12,2008

27
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer ilnawa.ora

ProDosed Rule Revision or Comment Rationale

(3) At least one long siring casing, using a sufficient Comment: NGWA supports this provision

number of centralizers, must extend to the injection

zone and must be cemented by circulating cement to

the surface in one or more stages.

(4) Circulation of cement may be accomplished by

staging. The Director may approve an alternative

method of cementing in cases where the cement

cannot be recirculated to the surface, provided the

owner or operator can demonstrate by using logs

that the cement does not allow fluid movement

behind the well bore.

(5) Cement and cement additives must be Comment: NGWA supports this provision and especially that

compatible with the carbon dioxide stream and the assessment should include the radial integrity of the

formation fluids and of sufficient quality and quantity cement.

to maintain integrity over the design life the geologic

sequestration project. The integrity and location of

the cement shall be verifled using technology

capable of evaiuating cement quality radially and

identifying the location of channels to ensure that

USDWs are not endangered.

(c) Tubing and packer.

(1) All owner and operators of Class VI wells must

inject fluids through tUbing with a packer set at a

depth opposite a cemented interval at the location

approved by the Director.

(2) In order for the Director to determine and specify

requirements for tubing and packer, the owner or

operator must submit the following information:

(i) Depth of selling:

0i) Characteristics of the carbon dioxide stream

(chemical content, corrosiveness, temperature, and

density);

(iii) Injection pressure;

December 12, 2008

28
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer6llnawa.ora

ProDosed Rule Revision or Comment Rationale

(iv) Annular pressure;

(v) Injection rate (intermittent or continuous) and

volume of the carbon dioxide stream;

(vi) Size of casing; and

(vii) Tubing tensile, burst, and collapse strengths.

§146.87 Logging, sampling, and testing prior to

iniection well oDeration.

(a) During the drilling and construction of a Class VI

injection well, the owner or operator must run

appropriate logs, surveys and tests to determine or

verify the depth, thickness, porosity, permeability,

and lithology of, and the salinity of any fonnation

fluids in, all relevant geologic formations to assure

confonnance with the injection well construction

requirements under§146.86, and to establish

accurate baseline data against which future

measurements may be compared. The owner or

operator must submit to the Director a descriptive

report prepared by a knowledgeable log analyst that

includes an interpretation of the results of such logs

and tests. At a minimum, such logs and tests must

include;

(1) Deviation checks during drilling on all holes

constructed by drilling a pilot hole which are enlarged

by reaming or another method. Such checks must be

at sufficiently frequent intervals to determine the

location of the borehole and to assure that vertical

avenues for fluid movement in the form of diverging

holes are not created during drilling; and

(2) Before and upon installation of the surface

casing:

(i) Resistivity, spontaneous potential, and caliper

logs before the casing is installed; and

December 12, 2008

29
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551,7379. ext. 560. creimer 'Vnawa.ora

ProDosed Rule Revision or Comment Rationale

(iO A cement bond and variable density log, and a

temperature log after the casing is set and

cemented.

(3) Before and upon installation of the long string

casing:

(i) Resistivity, spontaneous potential, porosity,

caliper, gamma ray, fracture finder logs, and any

other iogs the Director requires for the given geology

before the casing is installed: and

(iI) A cement bond and variable density log, and a Proposed revision: (ii) A cement bond, variable density log, NGWA supports inclusion of a radial cement

temperature log after the casing is set and and radial cement evaluation log and a temperature log after evaluation log in addition. The addition of

cemented. the casing is set and cemented. this test will help identify any potential

channels in the cement out from casing

(4) A series of tests designed to demonstrate the Comment: NGWA supports the inclusion of this series of

internal and external mechanical integrity of injection tests.

wells, which may include:

(i) A pressure test with liquid or gas;

(ii) A tracer survey such as oxygen-activation

logging;

(iii) A temperature or noise log;

(iv) A casing inspection log, if required by the

Director; and

(5) Any alternative methods that provide equivalent

or better information and that are required of and/or

approved of by the Director.

December 12, 2008

30
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer ilnowa.oro

Prooosed Rule Revision or Comment Rationale

(b) The owner or operator must take and submit to

the Director whole cores or sidewall cores of the

injection zone and confining system and formation

fiuid samples from the injection zone(s). The Director

may accept cores from nearby wells if the owner or

operator can demonstrate that core retrieval is not

possible and that such cores are representative of

conditions at the well. The Director may require the

owner or operator to core other formations in the

borehole.

(c) The owner or operator must record the fluid

temperature, pH, conductivity, reservoir pressure and

the static fiuid level of the injection zone(s).

(d) At a minimum, the owner or operator must

determine or calculate the following information

concerning the injection and confining zone(s):

(1) Fracture pressure;

(2) Other physical and chemical characteristics of the

injection and confining zones; and

(3) Physical and chemical characteristics of the

formation fluids in the injection zone.

(e) Upon completion, but prior to operation, the

owner or operator must conduct the following tests to

verify hydrogeologic characteristics of the injection

zone:

(1) A pump test; or

(2) Injectivity tests.

December 12, 2008

31
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551,7379, ext. 560. creimer 'ilnawa.ora

ProDosed Rule Revision or Comment Rationale

(I) The owner or operator must provide the Director

with the opportunity to witness all logging and testing

by this subpart. The owner or operator must submit a

schedule of such activities to the Director 30 days

prior to conducting the first test and submit any

changes to the schedule 30 days prior to the next

scheduled test.

§146.88 Injection well operating requirements.

(a) Except during stimulation, the owner or operator

must ensure that injection pressure does not exceed

90 percent of the fracture pressure of the injection

zone so as to assure that the injection does not

initiate new fractures or propagate existing fractures

in the injection zone. in no case may injection

pressure initiate fractures in the confining zone(s) or

cause the movement of injection or formation fiuids

that endangers a USDW.

(b) Injection between the outermost casing protecting

USDWs and the well bore is prohibited.

(c) The owner or operator must fill the annuius

between the tubing and the long string casing with a

non-corrosive fiuid approved by the Director. The

owner or operator must maintain on the annulus a

pressure that exceeds the operating injection

pressure, uniess the Director determines that such

requirement might harm the integrity of the well.

December 12, 2008

32
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer ilnawa.ora

Proposed RUle Revision or Comment Rationale

(d) Other than during periods of well work over

(maintenance) approved by the Director in which the

seaied tubing-casing annulus is of necessity

disassembled for maintenance or corrective

procedures, the owner or operator must maintain

mechanical integrity of the injection well at all times.

(e) The owner or operator must install and use

continuous recording devices to monitor: the

injection pressure; the rate, volume, and temperature

of the carbon dioxide stream; and the pressure on

the annulus between the tubing and the long string

casing and annulus fluid volume; and must install

and use alarms and automatic down-hole shut-off

systems, designed to alert the operator and shut-in

the well when operating parameters such as annulus

pressure, injection rate or other parameters

approved by the Director diverge beyond permitted

ranges and/or gradients specified in the permit;

(f) If a down-hole automatic shutdown is triggered or

a loss of mechanical integrity is discovered, the

owner or operator must immediately investigate and

identify as expeditiously as possible the cause of the

shutoff. If, upon such investigation, the well appears

to be lacking mechanical integrity, or if monitoring

required under paragraph (e) of this section

otherwise indicates that the well may be lacking

mechanical integrity, the owner or operator must

(1) Immediately cease injection;

December 12,2008

33
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geo[ogic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer i)nqwa.orq

Pronosed Rule Revision or Comment Rationale

(2) Take all steps reasonably necessary to determine

whether there may have been a release ofthe

injected carbon dioxide stream into any unauthorized

zone;

(3) Notify the Director within 24 hours;

(4) Restore and demonstrate mechanical integrity to

the satisfaction of the Director prior to resuming

injection; and

(5) Notify the Director when injection can be

expected to resume.

§146.89 Mechanical integrity.

(a) A Class VI well has mechanical integrity if:

(1) There is no significant leak in the casing, tubing

or packer; and

(2) There is no significant fluid movement into a

USDW through channels adjacent to the injection

well bore.

(b) To evaluate the absence of significant leaks

under paragraph (a)(1) of this section, owners or

operators must, following an initial annulus pressure

test, continuously monitor injection pressure, rate,

injected volumes, and pressure on the annulus

between tubing and long stem casing and annulus

fluid volume as specified in §146.88 (e);

(c) At least once per year, the owner or operator Proposed revision: At least once per year, the owner or There was a question as to whether one of

must use one of the following methods to determine operator must use one of the following methods, as approved these tests individually would suffice in all

the absence of significant fluid movement under by the director, to determine the absence of significant fluid circumstances. The change proposed is to

paragraph (a)(2) of this section: movement under paragraph (a)(2) of this section. allow the director to review the proposal.

(1) A tracer survey such as oxygen-activation

logging;

(2) A temperature or noise log; or

(3) A casing inspection log, if required by the

Director.

December 12, 2008

34
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer ilnawa.ora

ProDosed Rule Revision or Comment Rationale

(d) The Director may require any other test to

evaluate mechanical inte9rity under para9raph (a)(1)

or (a)(2) of this section. Also, the Director may allow

the use of a test to demonstrate mechanical integrity

other than those listed above with the written

approval ofthe Administrator. To obtain approval, the

Director must submit a written request to the

Administrator, which must set forth the proposed test

and all technical data supporting its use. The

Administrator must approve the request if it will

reliably demonstrate the mechanical integrity of wells

for which its use is proposed. Any altemate method

approved by the Administrator will be published in

the Federal Register and may be used in all States

in accordance with applicable State law unless its

use is restricted at the time of approval by the

Administrator.

(e) In conducting and evaluating the tests

enumerated in this section or others to be allowed by

the Director, the owner or operator and the Director

must apply methods and standards generally

accepted in the industry. When the owner or

operator reports the results of mechanical integrity

tests to the Director, he/she shall include a

description of the test(s) and the method(s) used. In

making his/her evaiuation, the Director must review

monitoring and other test data submitted since the

previous evaluation.

December 12, 2008

35
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer ilnawa.ora

ProDosed Rule Revision or Comment Rationale

(f) The Director may require additional or alternative

tests if the results presented by the owner or

operator under paragraph (d) of this section are not

satisfactory to the Director to demonstrate that there

is no significant leak in the casing, tubing or packer

or si9nificant movement of fluid into or between

USDWs resulting from the Injection activity as stated

in paragraphs (a)(1) and (2) of this section.

§146.90 Testing and monitoring requirements.

The owner or operator of a Class VI well must

prepare, maintain, and comply with a testing and

monitoring plan to verify that the geologic

sequestration project is operating as permitted and is

not endangering USDWs. The testing and monitoring

plan must be submitted with the permit application,

for Director approval, and must include a description

of how the owner or operator will meet the

requirements of this section. Testing and monitoring

associated with geologic sequestration projects

must, at a minimum, include:

(a) Analysis of the carbon dioxide stream with

sufficient frequency to yield data representative of its

chemical and physical characteristics:

(b) Installation and use, except during well walkovers

as defined in §146.86(d), of continuous recording

devices to monitor injection pressure, rate and

volume: the pressure on the annulus between the

tubing and the long string casing; and the annulus

fluid volume;

December 12, 2008

36
Docket - EPA-HQ-OW-2008-0390; Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer~ilnawa.ora

ProDosed Rule Revision or Comment Rationale

(c) Corrosion monitoring of the well materials for loss

of mass, thickness, crackin9, pitting and other signs

of corrosion must be performed on a quarterly basis

to ensure that the well components meet the

minimum standards for material strength and

performance set forth in §146.86(b) by:

(1) Placing coupons of the well construction

materials in contact with the carbon dioxide stream;

or

(2) Routing the carbon dioxide stream through a loop

constructed with the material used in the well; or

(3) Using an alternative method approved by the

Director;

(d) Periodic monitoring of the ground water quality Comment The monitoring should be site specific and include

and geochemical changes above the confining particular analytes at risk to the aquifer from the existing

zone(s) that may be a result of carbon dioxide geologic environment.

movement through the confining zone or additional

identified zones:

(1) The location and number of monitoring wells

must be based on specific information about the

geologic sequestration project, including injection

rate and volume, geology, the presence of artificial

penetrations and other factors;

(2) The monitoring frequency and spatial distribution

of monitoring wells must be based on baseline

geochemical data that has been collected under

§146.82(a)(6) and any modeling results in the area

of review evaluation required by §146.84(b);

(e) A demonstration of external mechanical integrity

pursuant to §146.89(c) at least once per year

throughout the duration of the geologic sequestration

project;

December 12, 2008

37
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer i/nQwa.ora

ProDosed Rule Revision or Comment Rationale

(f) A pressure fall-off test at least once every five Comment: What additional information does this test provide

years unless more frequent testing is required by the that is not available from other sources? The perception from

Director based on site specific information; some of our reviewers is that there may not be much

information that is gathered that is not already available from

other sources. If there is no significant additional information

provided, running the test may not be necessary.

(g) Testing and monitoring to track the extent of the

carbon dioxide plume and the position of the

pressure front by either monitoring for pressure

changes in the first formation overlying the confining

zone or using indirect, geophysical techniques (e.g.,

seismic, electrical, gravity, or electromagnetic

surveys andlor down-hole carbon dioxide detection

tools):

(h) At the Director's discretion, surface air monitoring

andlor soil gas monitoring to detect movement of

carbon dioxide that could endanger a USDW.

(1) The testing and monitoring plan must be based Proposed revision: (1) The testing and monitoring plan must Risk is more generally accepted and

on potential vulnerabilities within the area of review: be based on potential risks within the area of review; understood.

December 12, 2008

38
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer 'v.nqwa.orq

Proposed Rule Revision or Comment Rationale

(2) The monitoring frequency and spatial distribution

of surface air monitoring andlor soil gas monitoring

must reflect baseline data and the monitoring plan

must include how the proposed monitoring will yield

useful information on the area of review delineation

andlor compliance with standards under 40 CFR

144.12:

(0 Any additional monitoring, as required by the

Director, necessary to support, upgrade, and

improve computational modeling of the area of

review evaluation required under §146.84(b) and to

determine compliance with standards under 40 CFR

144.12: and

0) A quality assurance and surveillance plan for all

testing and monitoring requirements.

§146.91 Reporting requirements.

Proposed addition: (1) Class VI Test/Injection Well

Construction Permit

Proposed addition: (a) The Director shall require periodic data

reports and progress reports during construction that include:

Proposed addition: 1. Drille~s log

Proposed addition: 2. Geophysical surveys

Proposed addition: 3. Core analyses

Proposed addition: 4. Lithologic logs

Proposed addition: 5. Drill stem tests

Proposed addition: 6. Pump tests

Proposed addition: 7. Daily job (construction) reports

Proposed addition: 8. Water quality analyses

Proposed addition: (b) The frequency of reporting shall be

specified in the individual pennit

December 12, 2008

39
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext 560. creimeru 'ilnawa.ora

ProDosed Rule Revision or Comment Rationale

Proposed addition: (c) Interpretation of data is required in the

data reports or pro9ress reports at the completion of each

significant phase of construction, such as completion of test

well construction and testing, completion of injection weli

construction, and completion of injection weli testing.

Proposed addition: (d) The owner or operator shali submit

final reports of ali data coliected from the test injection eli with

interpretations to the Director with the application for a Class

VI Test/Injection Weli Construction and Testing Pemnit and a

Class VI Injection Weli Operation Permit shali include ali

information and data coliected under Section 146.87, with

appropriate interpretations

Proposed addition: (2) Class VI Operational Testing Pemnit

Proposed addition: (a) The owner or operator shali submit, as

part of the permit application, the proposed methodology for

coliection and reporting of operational data, to ensure that the

data is coliected, correlated, and reported in a fashion that

would enable the Director to evaluate weli performance.

Proposed addition: (b) Ali Class VI welis shali report monthly

the foliowing:

Proposed addition: 1. Operating reports to the Director on:

Proposed addition: a. The physical, chemical, and other

relevant characteristics of injection fluids;

Proposed addition: b. Daily reading of the pressure and flow

for each well. For each Class VI sequestration weli, a specific

injectivity test shali be perfomned quarterly;

Proposed addition: c. Monthly average, maximum and

minimum values for injection pressure, flow rate and volume,

and annular pressure; and

Proposed addition: d. The results of monitoring prescribed

under Section 146.90

Proposed addition: 2. Reporting the results, wtthin three

months after the completion of:

December 12,2008

40
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer j)nawa.ora

ProDosed Rule Revision or Comment Rationale

Proposed addition: a. Annular monitoring tests of mechanical

integrity;

Proposed addition: b. Any other test ofthe injection ell

conducted by the permittee if required by the Director; and

Proposed addition: c. Any well work over.

Proposed addition: (c) Specific injectivity testing shall be

performed while the pumping rate to the well(s) has been set

at a predetermined level and reported as the specific

injectivity index (gpm/specific pressure (psi9)). As part of this

test, the well shall be shut-in for a period of time necessary to

conduct a valid observation of pressure fall-off. The owner or

operator shall propose which pumping rate will be used based

on the expected flow, the design of the pump station including

the volume ofthe wet well and pump type(s), and the type of

pump controls used. The pumping rate(s) shall be included

as a condition of the operation permit

Proposed addition: (d) Re-evaluation of Area of Review. After

completion of the operatonal testing period, the Area of

Review shall be re-evaluated, using a calibrated, multi-phase

fluid flow model. The data collection during operational

testing must be adequate for calibration of the model. If a

calibrated model cannot be prepared using data collected

during operational testing, the owner or operator shall apply

for a new period of operational testing of up to two years in

order to collect the required data. No more than two

operational testing permits can be issued for any Class VI

well. Ifthe recalculated Area of Review includes any relevant

wells or penetrations through the confining zone that were not

reported in the permit application, a new tabulation of

penetrations as required in Section 146.84(c)(2) and (3) shall

be provided. Owners or operators must perform corrective

action as required in Section 146.84(d).

December 12, 2008

41
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer unawa.ora

Proposed Rule Revision or Comment Rationale

Proposed addition: (e) If physical or geochemical data such as

water quality, pressure changes, or mechanical integrity test

results indicate that fluid movement into or between

underground sources of drinking water may be occurring, the

permittee shall submit addttional data to provide reasonable

assurance that the injection operation is in compliance with

the requirements of this chapter. This additional data shall be

submitted with the periodic operations reports, the content

and frequency of which are specified in the individual permit.

Proposed addition: (f) A Class VI well permit shall be written to

require that if CFR Section 146.14(a) is applicable, progress

reports shall be submitted no later than thirty days following

each interim date and the flnal date of compliance.

Proposed addition: (3) Class VI Injection Well Operation

Permit.

Proposed addition: (a) The applicant shall submit, as part of

the penmit application, the proposed methodology for

collection and reporting of operational data, to ensure that the

data is collected, correlated, and reported in a fashion that

would enable the Director to evaluate well performance.

Proposed addition: (b) All Class VI wells shall report monthly

the following:

Proposed addition: 1. Operating reports to the Director on:

Proposed addition: a. The physical, chemical, and other

relevant characteristics of injection fluids;

Proposed addition: b. Daily readings of the pressure and flow

for each well. For each Class VI well, a specific injectivity test

shall be perfonmed quarterly;

Proposed addition: c. Monthly average, maximum and

minimum values for injection pressure, flow rate and volume,

and annular pressure; and

Proposed addition: d. The results of monitoring prescribed

under Section 146.90

Proposed addition: 2. Reporting the results, within three

months after the completion of:

December 12, 2008

42
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer ilnQwa.orQ

ProDosed Rule Revision or Comment Rationale

Proposed addition: a. Periodic tests of mechanical integrity:

Proposed addition: b. Any other test of the injection weli

conducted by the penmittee if required by the Director: and

Proposed addition: c. Any weli work over.

Proposed addition: (c) Specific injectivity testing shali be

performed while the pumping rate to the weli(s) has been set

at a predetermined ievei and reported as the specific

injectivity index (gpm/specific pressure (psig)). As part of this

test, the weli shali be shut-in for a period of time necessary to

conduct a vaiid observation of pressure fali-off. The owner or

operator shali propose which pumping rate will be used based

on the expected flow, the design of the pump stations

including the volume of the wet weli and pump type(s), and

the type of pump controls used. The pumping rate(s) shali be

included as a condition of the operation penmit.

December 12, 2008

43
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer 'Vnowa.ora

ProDosed Rule Revision or Comment Rationale

(d) Re-evaluation of Area of Review. Every five years, the

Area of Review shall be re-evaluated, using a calibrated, multi

phase fluid flow model. The data collection during operation

must be adequate for calibration of the model. If a calibrated

model cannot be prepared using data collected during

operation, the owner or operator shall, within 90 days, apply

for a new operation permit with a revised monitoring and

testing plan designed to collect the required data. The reissued Class VI operation permit shall be valid for a period of

no more than two years. After two years of operation under a

re-issued operating permit, the applicant shall again reevaluate the Area of Review using a calibrated, multi-phase

fluid flow model and re-apply for a five-year operating permit.

If the recalculated Area of Review includes any relevant wells

or penetrations whose total depth is greater than the depth to

the bottom of the lowermost USDW that were not reported in

the permit application, a new tabulation of penetrations as

required in Section 146.84(c)(2) and (3) shall be provided. Ow

CONT FROM ABOVE...must perform corrective action as

required in Section 146.84(d).

The owner or operator must, at a minimum, provide Proposed for deletion Covered in proposed Section 146.91 (3) and

the following reports to the Director, for each subsections

permitted Class VI well:

(a) Semi-annual reports containing: Proposed for deletion Covered in proposed Section 146.91(3) and

subsections

(1) Any changes to the physical, chemical and other Proposed for deletion Covered in proposed Section 146.91(3) and

relevant characteristics of the carbon dioxide stream subsections

from the proposed operating data;

(2) Monthly average, maximum and minimum values Proposed for deletion Covered in proposed Section 146.91 (3) and

for injection pressure, flow rate and volume, and subsections

annular pressure;

December 12, 2008

44
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer ilnowa.oro

Proposed Rule Revision or Comment Rationale

(3) A description of any event that exceeds operating Proposed for deletion Covered in proposed Section 146.91 (3) and

parameters for annulus pressure or injection subsections

pressure as specified in the permit;

(4) A description of any event which triggers a Proposed for deletion Covered in proposed Section 146.91(3) and

shutdown device required pursuant to §146.88(e) subsections

and the response taken;

(5) The monthly volume of the carbon dioxide stream Renumber 3(e)

injected over the reporting period and project

cumulatively;

(6) Monthly annulus fluid volume added; and Renumber 3(f); delete "and"

Proposed addition: (g) If physical or geochemical data such as

water quality, pressure changes, or mechanical integrity test

results indicate that fluid movement into or between

underground sources of drinking water may be occurring, the

permittee shall submit additional data to provide reasonable

assurance that the injection operation is in compliance with

the requirements ofthis chapter. This additional data shall be

submitted with the periodic operations reports, the content

and frequency of which are specified in the individual permit.

Proposed addition: (h) A Class VI well permit shall be written

to require that if CFR Section 146.41 (a) is applicable,

progress reports shall be submitted no later than thirty days

following each interim date and the final date of compliance.

(7) The results of monitoring prescribed under Proposed for deletion Covered in proposed Section 146.91 (3) and

§146.90. subsections

Covered in proposed Section 146.91(3) and

subsections

(b) Report, within 30 days the results of: Proposed for deletion Covered in proposed Section 146.91(3) and

subsections

(1) Periodic tests of mechanical integrity; Proposed for deletion Covered in proposed Section 146.91 (3) and

subsections

(2) Any other test of the injection well conducted by Proposed for deletion Covered in proposed Section 146.91 (3) and

the permittee if required by the Director; and subsections

(3) Any well work over. Proposed for deletion Covered in proposed Section 146.91 (3) and

subsections

December 12, 2008

45
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800,551,7379, ext 560, creimer 'Vnowa,ora

ProDosed Rule Revision or Comment Rationale

(c) Owners or operators must submit reports in an Renumber (4)

electronic format acceptable to the Director. At the

discretion of the Director, other formats may be

accepted,

§146.92 Injection well plugging.

(a) Prior to the well plugging, the owner or operator

must flush each Class VI injection well with a buffer

fluid, determine bottom hole reservoir pressure, and

perform a final mechanical integrity test

(b) Well Plugging Plan. The owner or operator of a Proposed revision: (b) Well Plugging Plan, The owner or The Area of Review re-evaluation should

Class VI well must prepare, maintain, and comply operator of a Class VI well must prepare; maintain; including trigger a review and updating of all the plans

with a plan that is acceptable to the Director. The updating on the same schedule as the update to the Area of (MMV, financial, plugging, emergency

requirement to maintain and implement an approved Review: and comply with a plan that is acceptable to the response...) on the same interval that the

plan is directly enforceable regardless of whether the Director, The requirement to maintain and implement an AOR is updated, NGWA suggests EPA

requirement is a condition of the permit The well approved plan is directly... check all timelines and make them

plugging plan must be submitted as part of the compatible,

permit application and must include the following

information:

(1) Appropriate test or measure to determine bottom

hole reservoir pressure;

(2) Appropriate testin9 methods to ensure

mechanical integrity as specified in §146.89;

(3) The type and number of plugs to be used:

(4) The placement of each plug including the

elevation of the top and bottom of each plug;

(5) The type and grade and quantity of material to be

used in plugging, The material must be compatible

with the carbon dioxide stream; and

(6) The method of placement of the plugs.

December 12, 2008

46
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer 'ilnqwa.orq

ProDosed Rule Revision or Comment Rationale

(c) Notice ofintent to plug. The owner or operator

must notify the Director at least 60 days before

plugging of a well. At this time, if any changes have

been made to the original well plugging plan, the

owner or operator must also provide the revised well

plugging plan. At the discretion of the Director, a

shorter notice period may be allowed.

(d) Plugging report. Within 60 days after plugging or Proposed revision: (d) Plugging Reports for Class VI Wells.

at the time of the next semi-annual report (whiChever Within 60 days after completion of plugging and abandonment

occurs earlier) the owner or operator must submit a of a well or well field the permittee shall submit to the Director

plugging report to the Director. If the semi-annual a final report which includes:

report is due less than 15 days after completion of

plugging, then the report must be submitted within 60

days after plugging. The report must be certified as

accurate by the owner or operator and by the person

who performed the plugging operation (if other than

the owner or operator.)

Proposed addition: (1) Certification of completion In Note: It is important that the engineer and/or

accordance with approved plans and specifications by an geologist have expertise and training in

appropriately qualified engineer of record or professional Injection well drilling technology, reservoir

geologist. characterization and injection well

construction and operation.

Proposed addition: (2) Evidence, such as a sealed copy or

certification from the county clerk, that a surveyor's plot of the

location of the abandoned well has been recorded in the

county courthouse property records.

§146.93 Post-injection site care and site closure.

December 12, 2008

47
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimerQilnqwa.orq

ProDosed Rule Revision or Comment Rationale

(a) The owner or operator of a Class VI well must Proposed revision: (a) The owner or operator of a Class VI The Area of Review re-evaluation should

prepare, maintain, and comply with a plan for post- well must prepare: maintain: including updating on the same trigger a review and updating of the well

injection site care and site closure that meets the schedule as the update to the Area of Review: and comply plugging plan, and the post injection site care

requirements of paragraph (a)(2) of this section and with a plan for post-injection site care and site closure that and closure plan. NGWA suggests EPA

is acceptable to the Director. meets the requirements of paragraph (a)(2) of this section and check all timelines and make them

is acceptable to the Director. compatible.

(1) The owner or operator must submit the postinjection site care and site closure plan as a part of

the permit application to be approved by the Director.

(2) The post-injection site care and site closure plan

must include the following information:

(i) The pressure differential between pre-injection

and predicted post-injection pressures in the

injection zone;

(ii) The predicted position of the carbon dioxide

plume and associated pressure front at site closure

as demonstrated in the area of review evaluation

required under §146.84(b):

(iii) A description of post-injection monitoring

location, methods, and proposed frequency: and

(iv) A proposed schedule for submitting post-injection

site care monitoring results to the Director.

(3) Upon cessation of injection, owners or operators

of Class VI wells must either submit an amended

post-injection site care and site closure plan or

demonstrate to the Director through monitoring data

and modeling results that no amendment to the plan

is needed.

(4) The owner or operator may modify and resubmit

the post-injection site care and site closure pian for

the Director's approval within 30 days of such

change.

December 12,2008

48
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Welis, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer unawa.ora

ProDosed Rule Revision or Comment Rationale

(b) The owner or operator shali monitor the site

foliowing the cessation of injection to show the

position of the carbon dioxide plume and pressure

front and demonstrate that USDWs are not being

endangered.

(1) The owner or operator shali continue to conduct Proposed revision: (1) The owner or operator shali continue to NGWA believes some number should be

monitoring as specified in the Director-approved post conduct monitoring as specified in the Director-approved post- included. 30 years is a number used in other

injection site care and site closure plan for at least injection site care and site closure plan for at least 30 years EPA programs. The next question was

50 years following the cessation of injection. At the following the cessation of injection. At the Director's whether the burden should be placed on the

Director's discretion, the monitoring will continue until discretion, the monitoring will continue until the geologic director to justify the longer number or on the

the geologic sequestration project no longer poses sequestration project no longer poses an endangerment to operator to prove the site is stabilizing. It is

an endangerment to USDWs. USDWs. suggested that the director be allowed to

approve both a shorter or longer timeframe.

With the next subsection, the burden is

placed on the owner or operator to prove a

shorter timeframe is acceptable, while

allowing in this subsection the director to

require monitoring beyond 30 years.

(2) If the owner or operator can demonstrate to the Proposed revision: (2) If the owner or operator can Makes this subsection compatible with 30

satisfaction of the Director before 50 years, based on demonstrate to the satisfaction of the Director that the year timeframe proposed by NGWA in

monitoring and other site-specific data, that the geologic sequestration project no longer poses an 146.93(b)(1)

geologic sequestration project no longer poses an endangerment to USDWs, the Director may approve an

endangerment to USDWs, the Director may approve amendment to the post-injection site care and site closure

an amendment to the post-injection site care and site plan to reduce the frequency of monitoring or may authorize

closure plan to reduce the frequency of monitoring or site closure before the end of the 30-year period.

may authorize site closure before the end of the 50-

year period.

(3) Prior to authorization for site closure, the owner

or operator must submit to the Director a

demonstration, based on monitoring and other sitespecific data, that the carbon dioxide plume and

pressure front have stabilized and that no additional

monitoring is needed to assure that the geologic

sequestration project does not pose an

endangerment to USDWs.

December 12, 2008

49
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800,551,7379, ext. 560. creimer i)nawa,ora

ProDosed Rule Revision or Comment Rationale

(4) If such a demonstration cannot be made (i.e., if Proposed revision: (4) If such a demonstration cannot be Makes this subsection compatible with 30

the carbon dioxide plume and pressure front have made (i.e. if the carbon dioxide plume and pressure front have year timeframe proposed by NGWA in

not stabilized) after the 50 year period, the owner or not stabilized) after the 30 year period, the owner or operator 146,93(b)(1)

operator must submit to the Director a plan to must submit to the Director a plan to continue post-injection

continue post-injection site care. site care.

(c) Notice ofintent for site closure, The owner or

operator must notify the Director at least 120 days

before site closure. At this time, if any changes have

been made to the original post-injection site care and

site closure plan, the owner or operator must also

provide the revised plan. At the discretion of the

Director, a shorter notice period may be allowed,

(d) After the Director has authorized site closure, the

owner or operator must plug all monitoring wells in a

manner which will not allow movement of injection or

formation fluids that endangers a USDW.

(e) Once the Director has authorized site closure, the

owner or operator must submit a site closure report

within 90 days that must thereafter be retained at a

location designated by the Director. The report must

include:

December 12, 2008

50
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wens, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerviile, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer ilnQwa.orQ

ProDosed Rule Revision or Comment Rationale

(1) Documentation of appropriate injection and

monitoring wen plugging as specified in §146.92 and

paragraph (c) of this section. The owner or operator

must provide a copy of a survey plat which has been

submitted to the local zoning authority designated by

the Director. The plat must indicate the location of

the injection wen relative to permanently surveyed

benchmarks. The owner or operator must also

submit a copy of the plat to the Regional

Administrator ofthe appropriate EPA Regional

Office;

(2) Documentation of appropriate notification and

information to such State, local and tribal authorities

as have authority over drilling activities to enable

such State and local authorities to impose

appropriate conditions on subsequent drilling

activities that may penetrate the injection and

confining zone(s): and

(3) Records reflecting the nature, composition and

volume of the carbon dioxide stream.

(I) Each owner or operator of a Class VI injection well

must record a notation on the deed to the facility

property or any other document that is normally

examined during title search that wiil in perpetuity

provide any potential purchaser of the property the

following information:

(1) The fact that land has been used to sequester

carbon dioxide;

(2) The name of the State agency, local authority,

and/or tribe with which the survey plat was filed, as

well as the address of the Regional Environmental

Protection Agency Office to which it was submitted;

and

(3) The volume of fluid injected, the injection zone or

zones into which it was injected, and the period over

which injection occurred.

December 12, 2008

51
Docket - EPA-HQ-OW-2008-0390: Comments on VIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800,551,7379, ext 560, creimer ~nqwa.orq

Proposed Rule Revision or Comment Rationale

(g) The owner or operator must retain for three years

following site closure, records collected during the

post~injection site care period. The owner or operator

must deliver the records to the Director at the

conclusion of the retention period, and the records

must thereafter be retained at a location designated

by the Director for that purpose,

§146,94 Emergency and remedial response.

(a) As part of the permit application, the owner or Proposed revision: (a) As part of the permit application, the Keep same update schedule as AOR

operator must provide the Director with an owner or operator must provide the Director with an

emergency and remedial response plan that emergency and remedial response plan that describes actions

describes actions to be taken to address movement to be taken to address movement of the injection or formation

of the injection or formation fluids that may cause an fluids that may cause an endangerment to a USDW during

endangerment to a USDW during construction, construction, operation, closure and post-closure periods,

operation, closure and post-Closure periods, The emergency and remedial response plan must be

reviewed and updated, as necessary, on the same schedule

as the update to the Area of Review,

(b) If the owner or operator obtains evidence that the

injected carbon dioxide stream and associated

pressure front may cause an endangerment to a

USDW, the owner or operator must:

(1) Immediately cease injection:

(2) Take all steps reasonably necessary to identify

and characterize any release:

(3) Notify the Director within 24 hours; and

(4) Implement the emergency and remedial response

plan approved by the Director.

(c) The Director may allow the operator to resume

injection prior to remediation if the owner or operator

demonstrates that the injection operation will not

endanger USDWs,

December 12, 2008

52
Docket - EPA-HQ-OW-2008-0390: Comments on UIC Requirements for Geologic Sequestration Wells, 73 FR 43492

National Ground Water Association, 601 Dempsey Rd, Westerville, OH 43081

Contact: Christine Reimer, NGWA, 800.551.7379, ext. 560. creimer vnawa.ora

Proposed Rule Revision or Comment Rationale

(d) The owner or operator must notify the Director

and obtain his approval prior to conducting any well

work over.

December 12, 2008

53
Letter ID: 0142 

Commenter: Christine Reimer 

Organization: National Ground Water Association 

Letter ID: 0142 Comment ID: 22544 Letter Lines: 99 to 113 

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

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

Comment: Classification of Injection Wells for Carbon Sequestration, Class II Injection 

Well Transition, and Grandfathering 

The EPA published a guidance document in March of 2007 recommending that the 

geologic sequestration experimental projects during this period of research use 

the Class V experimental category for classification of the injection wells 

(Using the Class V Experimental Technology Well Classification for Pilot 

Geologic Sequestration Projects - EPA 2007). These projects are currently 

underway at the Department of Energy’s (DOE’s) National Energy Technology 

Laboratory Regional Partnership test sites. Thus, there will be a need in the 

future for a regulatory mechanism for transition of these Class V experimental 

wells to Class VI operational status. There are also a number of Class II 

enhanced oil recovery (EOR) wells that have been used for testing of the 

sequestration process. These wells, too, may need a mechanism for transition to 

Class VI for operational use. 

Individual Response: EPA agrees that many Class II and Class V experimental technology 

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

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

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

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

§146.86(b) and §146.87(a). 

EPA does not believe that other requirements (e.g., MITs, siting, monitoring, operational, and 

AoR requirements) should also be grandfathered. Following re-permitting of the well as Class 

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

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

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

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

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

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

rule for additional detail on these requirements. 

Letter ID: 0142 Comment ID: 22545 Letter Lines: 115 to 226 

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

1
Comment Code: 2066 1.5.3.3 Grandfathering construction of Class V wells (seeking comment) 

Comment Code: 3130 2.1.3 Comments that operators should submit more (or different) 

geologic data than proposed 

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

comment) 

Comment: The NGWA Carbon Sequestration Task Force recommends that the experimental 

phase 

extend beyond the regional partnerships to each site proposed for productionscale injection of carbon dioxide. It is recommended that at least one well at 

each site be constructed under the Class V experimental category, and that 

testing of the adequacy of the geologic environment for geologic sequestration 

of carbon dioxide be conducted prior to permitting any well in the Class VI 

category at the site. 

The transition of carbon dioxide injection wells from Class II (Enhanced Oil 

Recovery wells) to Class VI (carbon sequestration wells) will presumably be 

requested when production of the petroleum has ceased. Liquid carbon dioxide 

from a distant source, such as a power plant, can be stored in the depleted 

petroleum reservoir even after production has ceased, necessitating a change in 

classification of the injection well. The new use of the wells involves much 

longer storage time, and raises concerns about mechanical integrity and long 

term effects, including geochemical changes, on underground source of drinking 

water (USDWs). The reclassification should depend on a positive outcome from a 

Class V experimental program conducted in the depleted reservoir, as described 

below. 

The "grandfathering" of Class V carbon sequestration wells would mean allowing 

experimental wells to be permitted for operation after the testing period is 

over. The NGWA Carbon Sequestration Task Force recommends that each carbon 

sequestration system or wellfield have an experimental phase, and not rely on 

results from distant experimental locations. Thus, nearly every operational 

well would start as a Class V experimental well, or would go through a Class VI 

testing phase, before being permitted for long-term operation. The transition 

to Class VI operational status would require demonstrating that the minimum 

requirements are met at that location. Most wells would go through the 

following permitting phases: 

- Class V experimental well construction permit: This permit would allow 

geologic and geophysical testing, aquifer testing, laboratory work, etc, but 

would not include injection of CO2 (only potable water injection testing would 

be allowed). 

- Class VI experimental well operational testing permit: At this stage, 

the full monitoring facilities would need to be constructed. This permit would 

allow test injection of liquid CO2 at rates high enough to demonstrate that the 

2
location meets the minimum requirements for operation, for a period of up to two 

years. 

- Class VI operation permit: After demonstrating that the location and 

the well meet all the minimum requirements for injection of CO2, the operation 

permit can be issued. 

The goals of the experimental well Class V construction permit would be to make 

the following demonstrations: 

- A receiving zone of sufficient depth, area extent, thickness, porosity, and 

permeability is present; 

- Lithologic description, geological name, thickness and depth of each confining 

unit above the storage aquifer, and of each USDW. 

- A trapping mechanism that is free of pathways for migration of injected fluids 

into a USDW. These pathways may include major non-sealing faults, porous beds 

within the confining unit, changes of facies trending toward more porous units 

and man-made structures such as wells or mine shafts. A trapping mechanism is 

defined as a geologic environment that prevents vertical and horizontal movement 

of fluids into a USDW; The volume of the trap shall exceed the proposed total 

volume of injected carbon dioxide for the life of the proposed facility 

- Identification of all confining units between the primary injection/storage 

zone and the lowermost USDW, and their adequacy to contain the injected fluid. 

Unless the only feasible injection zone has only one confining unit separating 

it from the lowermost USDW, this demonstration includes adequacy of confinement 

for both the primary confining unit and a secondary containment system that 

extends to the base of the lowermost USDW and is completely redundant of the 

primary confining system and could confine the injected CO2 should the primary 

system fail. In locations where the secondary containment system is not 

possible, the applicant shall propose an alternative system of early warning of 

failure of the primary confining unit in order to avoid impacting any USDW 

should that confinement fail. This demonstration applies in the horizontal 

sense as well, demonstrating one or more mechanisms containing the fluid from 

horizontal movement into a USDW in the storage aquifer at a distant location. 

- The construction of an operational monitoring system meeting all the 

requirements described in this document’s MMV section, and demonstration of the 

adequacy of this system to meet those requirements. 

- Demonstration of mechanical integrity 

Having made the foregoing demonstrations, a Class VI operational testing permit 

can be issued for a period of up to two years. The goals of the experimental 

3
well Class VI operational testing permit would be to make the following 

demonstrations: 

- A hydraulic demonstration of the adequacy (depth, area extent, thickness, 

porosity, and permeability) of the storage zone, using monitoring data and 4-D 

seismic monitoring of the extent of the CO2 plume. 

- Demonstration of the adequacy of the trap for 5/10 years of injection at the 

proposed rate. The volume of the trap shall exceed the proposed total volume of 

injected carbon dioxide for the 5/10 years of the first operation permit. 

- Demonstration of the adequacy of confinement under operational conditions 

using monitoring data and a method of detecting the extent of the CO2 plume in 

the storage aquifer, such as 4-D seismic monitoring or direct sampling. 

- Re- evaluation of the Area of Review and extent of the zone of endangering 

influence. 

- Re-evaluation of mechanical integrity, using the buoyancy of the injected CO2 

to better measure external mechanical integrity. The re-evaluation shall 

include the testing required during the initial MIT, as well as evaluation of 

the cement for carbonation, or chemical weathering by CO2 

Under this permitting scenario, the vast majority of Class V experimental wells 

would be constructed after the Class VI standards had been published. The 

"grandfathering" of Class V wells that do not meet the Class VI construction 

standards would only be needed for DOE test sites established before rulemaking 

was complete. If these wells include the ongoing mechanical integrity 

monitoring of annular fluid pressure and composition, and they pass periodic 

mechanical integrity testing, they should be able to follow the same permitting 

procedures to become operational Class VI wells. 

Individual Response: EPA believes that submittal and review of monitoring data (as required at 

§146.90) and the AoR reevaluation process (§146.84(e)) will provide an opportunity for an 

ongoing review of the site and a dialogue between the Director and the owner or operator to 

ensure that the project is being operated in a manner that protects USDWs from endangerment. 

EPA notes that changes to these plans require a permit modification under §144.39, the public 

must be notified according to the public comment procedures under 40 CFR 124. 

Please see the final rule and the discussion of geologic site characterization in the preamble for 

additional information. 

EPA disagrees that every GS well should initially be permitted as a Class V well. The Agency 

believes that the tailored Class VI requirements including extensive requirements for geologic 

site characterization at §146.82, AoR evaluation at §146.84, and testing of the well during 

drilling at §146.87 are appropriate to ensure that permitting authorities have the necessary 

information to evaluate whether a specific site will allow safe injection of CO2. EPA adds that 

submittal and review of monitoring data (as required at §146.90) and the AoR reevaluation 

process (§146.84(e)) will provide an opportunity for an ongoing review of the site and a dialogue 

between the Director and the owner or operator to ensure that the project is being operated in a 

4
manner that protects USDWs from endangerment. Given this approach to permitting Class VI 

projects, EPA believes that the requirements for grandfathering of construction at §146.81(c) are 

necessary and appropriate. 

Letter ID: 0142 Comment ID: 22546 Letter Lines: 229 to 345 

Comment Code: 3130 2.1.3 Comments that operators should submit more (or different) 

geologic data than proposed 

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

comment) 

Comment: Geologic Characterization 

The UIC program is required under the Safe Drinking Water Act to protect USDWs 

from contamination from fluids injected into the subsurface. Part of this 

requirement is the demonstration that the injected fluids will not migrate, 

through buoyancy, ground-water flow or injection pressure, into USDWs. This 

demonstration is based on the characteristics of the geological environment 

where injection is to take place. The current UIC regulations require 

investigation of waste disposal sites through an application-phase data summary 

(Area of Review study) and geologic testing while drilling the pilot hole of the 

injection well. In general, the critical attributes of the injection and 

confining units are measured during pilot hole drilling, and the integrity and 

extent of those units are addressed in the literature review and Area of Review 

study at the application phase. Because of the large volumes of carbon dioxide 

that are expected to be injected, and the vast extent of the storage zones, it 

is expected that more detailed information will be needed over a larger area for 

carbon sequestration than has been historically needed for injection of other 

wastes. 

The NGWA recommends that the adequacy and safety of injection of liquid carbon 

dioxide at each site be evaluated by multi-phase, variable density ground-water 

modeling, supported by extensive field investigations (see section General 

Comments on the Use of Modeling for Ground-Water Protection Related to CO2 

Sequestration, below) These models should be included at the experimental 

well permit application phase as conceptual models, and progressively refined as 

data are collected during well construction and testing, and monitoring of 

operations. 

The test injection well/operational testing permit application for a carbon 

sequestration injection well must address the geological characteristics of the 

site. The data presented at this stage should be adequate to make and calibrate 

an appropriate ground-water model. The necessary elements of the geologic 

system for carbon sequestration include: 

- A receiving zone of sufficient depth that the injected carbon dioxide 

5
can be maintained in a supercritical state 

- Of sufficient areal extent that it includes the entire zone of endangering 

influence 

- Of sufficient thickness and porosity to contain the volume of carbon dioxide 

injected over the life of the proposed system 

- Of sufficient permeability to accept the peak daily flow of injected carbon 

dioxide from the facility 

- A trapping mechanism (consisting of either impermeable barriers or 

geochemical/mixing barriers) that is free of vertical or horizontal pathways for 

migration of injected fluids into a USDW. The volume of the trap shall exceed 

the proposed total volume of injected carbon dioxide for the life of the 

proposed facility 

- A primary confining system of sufficient areal extent, thickness and 

competency to contain the injected fluid at proposed rates and volumes without 

initiating or propagating fractures in the confining zone 

- Unless the only feasible injection zone has only one confining unit separating 

it from the lowermost USDW, a secondary containment system that is completely 

redundant of the primary confining system and could confine the injected CO2 

should the primary system fail. 

- The identification of a monitoring zone between the primary and secondary 

confining units. In locations where the secondary containment system is not 

possible, the applicant shall propose a monitoring formation to provide early 

warning of failure of the primary confining unit in order to avoid impacting any 

USDW should that confinement fail. 

- Provide depth and completion information of all USDWs that may be affected by 

the injection if fluid movement does occur. 

- Provide geochemical information on subsurface aquifers, including all USDWs: 

Baseline geochemical data on water-rock- CO2 geochemistry and mineral reactions, 

maps and cross sections. 

These elements should be identified in existing well records, in geologic 

literature, and by using the results of the exploratory program. The critical 

storage and confining units should be shown to exist over the entire area of 

review, or zone of endangering influence 

The operation permit application should also include a preliminary multi-phase 

numerical transport model for CO2 and formation fluid, including all of the 

elements listed above. This model should include at least one calibration 

scenario and will be used to provide a preliminary evaluation of the adequacy 

and safety of injection of carbon dioxide at the site, as well as a preliminary 

calculation of the potential storage volume of the geologic structure. 

Each permit application for a carbon sequestration injection well must include 

an Area of Review study, which addresses the entire zone of endangering 

influence of the carbon sequestration operation, including the area impacted 

after cessation of injection due to buoyancy transport. The zone of endangering 

6
influence shall be determined by the ground-water model described above and 

illustrated with maps and cross sections. 

Provide information on the geologic structure of the proposed site, including: 

- Maps and cross sections of local geologic structure. Each cross section 

should include the location and depth of relevant data sources, including 

geophysical logs, that were used in developing the cross section 

- Geological name and lithologic description of each injection zone, primary 

and/or secondary confining unit, and USDW 

- Data on the receiving formation and the confining systems : 

1. Size of the storage reservoir, and extent of the confining units in 

comparison to the area of endangering influence 

2. Presence or absence of a secondary confining unit 

3. Porosity, and permeability of the storage zone and confining units, 

including any geology/facies changes, based on field data which may 

include geologic cores, outcrop data, 3-dimensional seismic surveys, and 

well logs 

4. Capacity of the storage zone in comparison to the proposed total 

volume of carbon dioxide to be stored, 

5. Evaluation of the long-term effectiveness of the storage structure, 

including expected pathways of migration of injected carbon dioxide, and 

the horizontal barriers to fluid movement 

- Geomechanical information on fractures, stress, rock strength, and in situ 

fluid pressures within the primary and secondary containment units and confining 

systems 

- Identification of potential pathways for migration of injected fluids and 

determination that they would not conduct a volume of fluid that would cause a 

violation of the prohibition of fluid movement as it applies to the class of 

well that is to be constructed 

- Identification of potential risks within the zone of endangering influence, 

including degradation of water quality in USDWs, gas buildup in USDWs, reduction 

of porosity through geochemical changes in USDWs, and population that could be 

affected by gas releases. 

- List of penetrations into the injection zone and secondary containment system. 

- Information on seismic history and the presence/depth of seismic sources 

Individual Response: EPA agrees that extensive geological data collection and computational 

modeling, similar to what the commenter suggests, are important components of characterizing a 

potential GS site. For this reason, the GS regulation requires owners or operators to collect and 

submit extensive geological data (specified at §146.82) on the proposed GS site, including the 

injection and confining zones. Operators must also delineate the AoR using computational 

modeling that accounts for the multiphase flow of CO2 and native fluids (§146.84(c)), based on 

the geological data collected and proposed injection operations. 

EPA disagrees with the comment that all sites should be evaluated by multi-phase, variable 

7
density groundwater modeling; instead, EPA believes that owners or operators should have the 

flexibility to select models that are most appropriate to site conditions and available data types 

and amounts. EPA is also requiring that the AoR be reevaluated at a frequency of every 5 years 

using monitoring and operating data to verify that the CO2 plume and pressure front are 

behaving as predicted in AoR calculation models (§146.84(e)). 

Letter ID: 0142 Comment ID: 22547 Letter Lines: 347 to 382 

Comment Code: 3866 2.3.3.3 Logging and testing requirements (40 CFR 146.87) 

Comment: During drilling and construction of the injection well, important, site-specific 

data must be collected to verify the facts included in the application, provide 

quantitative data for refinement of the ground-water model, and test the 

injectivity of the proposed injection zone. The testing currently recommended 

in the regulations during construction of Class I wells includes geophysical 

logs run during drilling, deviation checks to ensure that reamed holes do not 

deviate from pilot holes, leaving conduits in the formation, and logs to measure 

the integrity of the completed wells. The NGWA recommends the following testing 

during construction: 

A. Identification of the lowermost USDW should be confirmed during 

drilling, using tests such as the following: 

1. Sampling discharge from packer tests (straddle packers or single-packer 

bottom-hole test). 

2. Cross plots of induction or resistivity with sonic/neutron/density 

porosity measurements and deduction of fluid resistivity using Archies Law 

(verification of porosity with core samples) 

3. Bottom-hole water sampling during pilot hole drilling (with mud) 

4. Depth sampling in pilot hole while pumping 

5. Collection, logging, and archiving, of rock cores through the sealing 

and target formations. 

B. The demonstration of confinement is the most critical task in 

construction of the well. Some information can be collected only prior to the 

installation of casing so careful consideration should be given to formation 

sampling before the well is completed. We recommend that borehole geophysical 

methods, such as, but not limited to, resistivity, neutron, gamma, and density 

logs, be combined with formation imaging such as, but not limited to, digital 

video and acoustic televiewer logging to specify lithologic units, geologic 

properties, and faults or fractures. Hydraulic testing such as straddle packer 

injection can be completed prior to completion of the well. After completion, 

long-term pumping tests should be conducted over a sufficient time period to 

assure near-pseudo-steady state head conditions in the vicinity of the well. 

Interpretation of these data and tests should be used to refine the ground-water 

flow and transport model. 

8
Individual Response: EPA agrees there are numerous tests available to characterize subsurface 

formations, including identifying the lowermost USDW. The owner or operator must describe 

his or her proposed formation testing program as part of the permit application, pursuant to 

§146.82(a)(8). The Director will evaluate the proposed formation testing plan, along with sitespecific geologic information, the AoR and corrective action plan, and proposed well 

construction procedures. If, based on a review of this information, the Director determines that 

additional logs and tests are necessary to provide assurance that USDWs will be protected from 

endangerment, he or she has authority at §146.87(a)(5) to require additional testing. EPA adds 

that during the permit application process, the owner or operator and the permitting authority 

will work together to determine which tests are appropriate, based on the site-specific 

circumstances. 

EPA is developing guidance on monitoring and testing that will describe recommended tests and 

procedures to assist owners/operators and Directors in evaluating the requirements for preoperational logging and testing under §146.87. This guidance will be available on EPA’s website 

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

Letter ID: 0142 Comment ID: 22548 Letter Lines: 385 to 504 

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

comment) 

Comment: General Comments on the Use of Modeling for Ground-Water Protection Related to 

CO2 Sequestration 

Quantitative modeling must play an important role in the assessment of groundwater protection related to CO2 sequestration projects. A ‘quantitative model’ 

is defined here as a quantitative mathematical analog of the real subsurface 

system. 

Three overall purposes for quantitative modeling are generally recognized: 

1. Generic: Model used in a hypothetical sense 

2. Interpretive: Model used to understand system dynamics 

3. Predictive: Model used to predict future behavior of the subsurface 

system. 

All three purposes are generally needed for a CO2 sequestration project. For 

example, generic models are used to determine the important physical or 

geochemical mechanisms that dominate transport or trapping of CO2. An 

interpretive model is applied to test specific hypotheses regarding these 

behaviors. Predictive modeling provides the basis for design of the final 

injection scheme and establishment of potential risk to drinking water. 

Quantitative models may range from simple analytic calculations to complex 

9
multi-component multi-phase coupled three-dimensional numerical simulations. The 

choice of quantitative model (analytic or numerical) depends in large part on 

the ultimate objective of the modeling study, and on practical constraints 

including availability of data and computational limitations. Which type of 

model or combination of models is most appropriate for a specific situation 

depends on many factors. In general, using a combination of modeling and 

analysis techniques is recommended, because different levels of complexity are 

needed at various stages of a project and for different objectives, and 

application of multiple modeling techniques can be used for "cross-checking" and 

overall quality assurance. 

Numerical models are widely available and usually represent a relatively wide 

range of physical and chemical processes, spatial heterogeneity of material 

properties, and nonlinear interactions among different processes. While these 

kinds of models allow for substantial flexibility and can provide detailed 

predictions of system behavior, they also require large amounts of data, much of 

which may be difficult to obtain or estimate. As such, specific choices of 

models must be made with care, and some situations may most effectively be 

addressed by a combination of different kinds of models. 

Quantitative modeling, whether conducted with analytical or numerical modeling 

tools, provides significant insights into system behavior. The advantages of 

such models are that they: 

1. provide a framework for data collection centered about a specific set 

of transport and geochemical behaviors. 

2. allow communication and the interpretation of these data in the 

context of scientific principles and facilitate collaboration among 

engineers, scientists, and regulators. 

3. may be extended far into the future using multiple design scenarios 

4. can be compared to measured data which allow hydraulic and 

geochemical parameters to be estimated. 

5. Can be used to access the performance of the system in a long 

performance period for which field and laboratory data are not 

available. 

It is important to recognize that all quantitative mathematical models are based 

upon a "conceptual model" which defines the important fluid and chemical 

interactions as well as the spatial and temporal extent of the model. Because 

the conceptualization is a critical part of the modeling activity, it is 

important to explore multiple conceptual models during the modeling process to 

assure that important scenarios are not excluded from the analysis. 

The selection of which quantitative model to use relies on the identification of 

the physical/chemical parameters and functions that must be represented. Because 

the injection and migration of CO2 into the subsurface is hydraulically and 

10
chemically complex, comprehensive quantitative modeling would have to include 

many parameters and factors -- including the flow of miscible and immiscible 

phases in all potential states as well as chemical reactions among fluids and 

with the geologic media and necessary heat transfer. The geologic medium may 

also deform or be chemically altered in response to the presence of CO2. The 

complexity of these coupled processes, in the presence of complex 

hydrostratigraphy, lead to models that are at the limit of the current 

capabilities of available computer hardware and software. It is likely, 

therefore, that multiple models may be required to provide the necessary 

insights into the important physical and chemical processes. Ultimately, sound 

scientific and engineering judgments should be applied to determine which 

physical or chemical processes are most important for a given analysis, and to 

make assumptions that are consistent with those judgments. For example, during 

the injection phase of a CO2 operation, multi-phase flow physics tend to 

dominate other processes such as interphase mass transfer and geochemical 

reactions. This separation of time scales can lead to important simplifications 

for the purpose of risk assessment. Similar analysis of spatial scales can 

provide additional simplifications, leading to practical modeling tools for the 

purpose of risk assessment. It is, therefore. imperative that modeling experts 

participate and manage all phases of the modeling process, in concert and 

constant communication with the project team and the appropriate regulatory 

reviewers, to ensure that appropriate and comprehensive quantitative modeling 

tools are applied successfully." 

The process of comparing simulated and measured predictions for the purpose of 

developing a more accurate depiction of a subsurface flow system is generally 

referred to as "model calibration" in the ground-water literature. (This same 

process is referred to as "inverse modeling" in exploration geophysics and 

"history matching" in petroleum reservoir simulation.) Model calibration 

involves varying the parameters of the quantitative model to achieve the minimum 

difference between measured and predicted responses. This is usually achieved 

through an automated process using non-linear regression or a heuristic 

algorithm to optimize the problem (e.g. as implemented in the PEST or UCODE 

software). In the case of ground-water modeling, the predicted and measured 

data are usually pressures, discharge rates, or concentrations of fluids or 

dissolved species. These data may not be available during the design stage of 

a CO2 project unless wells already exist in the target formation. As wells are 

drilled and geologic and fluid information are collected, however, the model 

should be refined and calibrated. Most automated calibration procedures allow 

for statistical estimation of confidence in the estimated parameters, providing 

a basis for quantifying the sensitivity of the model to changes in its 

parameters, and for performing quality control of model predictions. 

The design, construction, and calibration of analytic or numerical models should 

follow a quality assurance and quality control procedure. These procedures 

should include benchmarking of the mathematical predictions against known 

11
results, a method for assuring input data quality and lineage, and a statistical 

analysis of the predictive results against available data and/or sensitivity 

analyses. ASTM guides are available for ground-water modeling and code 

benchmarking (e.g. Guides D 6025, D 5447, D 5490, D 5611, D 5609, D 5610, and D 

5718). 

Individual Response: EPA agrees that complex modeling techniques are necessary to calculate 

the AoR while adequately accounting for the complexities of a GS site and all phases of a CO2 

plume. EPA believes, based on the research that supported the modeling requirements in the GS 

regulation (as described in the background document, "Computational Modeling of Underground 

Injection of Carbon Dioxide for Determination of Area-of-Review and Potential Risk to 

Underground Sources of Drinking Water" cited in the proposed rule preamble as USEPA, 

2008d), that technology has advanced to the point that a CO2 injection project can be 

appropriately modeled to predict and track a CO2 plume (and pressure front). Each AoR 

calculation will be reviewed based on site-specific geologic conditions, planned operating 

conditions, and available modeling and computational technology. EPA agrees that appropriate 

data quality review should be conducted during AoR modeling. Methods for assuring input data 

quality and lineage, as well as statistical analysis of predictive results may be used during 

evaluation of a permit application, at the discretion of the Director. 

EPA anticipates that modeling technology will continue to 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 increased protection of USDWs from endangerment. 

EPA adds that, to address uncertainty in modeled results, particularly over the long term, it is 

requiring that the AoR be reevaluated (under 146.84(e)) to verify the CO2 plume is behaving as 

predicted and to allow for necessary revisions to corrective action or monitoring. The final GS 

regulation includes a requirement that the AoR be reevaluated at least every 5 years (an 

adjustment from the ten year interval in the proposal), which should further address the 

commenters' concerns. This frequency will provide the Agency with information on AoR 

reevaluations to support subsequent regulatory evaluations that are part of the Agency's adaptive 

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 appropriate 

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

appropriate or necessary. 

Letter ID: 0142 Comment ID: 22549 Letter Lines: 83 to 96 ; 1259 to 1260 ; 1276 to 1278 

Comment Code: 1220 1.1.1.1 Terminology and definitions 

Comment Code: 4400 2.4.4.3 Allowing injection above or between USDWs (seeking comment) 

Comment: Definition of Underground Sources of Drinking Water 

NGWA recommends that US. EPA reevaluate the appropriateness of the definition of 

an underground source of drinking water (USDW) as one containing less than 

12
10,000 ppm total dissolved solids prior to large-scale licensing of carbon 

capture and storage (CCS) sites to ensure future drinking water supplies are not 

unintentionally degraded. For example, a recent article reported that deep 

brackish ground water, approximately 12,000 TDS, is under consideration as a 

water source for a development in Sandoval County, New Mexico. The article 

notes that the cost of water treatment is expected to be less than obtaining 

existing water rights (Sengebush, 2008) In 2003, water managers in 36 states 

anticipated shortages in localities, regions, or statewide in the next ten years 

(U.S. General Accounting Office, 2003). The potential for the increased use of 

brackish ground water for water supplies must be anticipated and considered. 

Sengebush, Robert M., INTERA, Inc. Deep Brackish Water Considered for New 

Mexico Development. Southwest Hydrology, March/April 2008, p. 8. 

U.S. General Accounting Office. Freshwater Supply: States’ Views of House 

Federal Agencies Could Help Them Meet the Challenges of Expected Shortages 

(GAO-03-514). July 2003, p. 1. 

Individual Response: EPA is not changing the USDW definition; changing the definition of a 

USDW is outside the scope of the GS rulemaking. The GS rule focuses on ensuring protection of 

USDWs, as required under the SDWA, by establishing regulations to ensure the safe injection of 

CO2 for long-term storage. 

EPA recognizes that there is increasing demand for water resources and that technology 

improvements may make high TDS aquifers viable drinking water sources. EPA believes these 

potential resources should be considered when injection depth waivers are sought. Therefore, the 

final GS rule at §146.95(b) requires the Director to consider these issues in determining whether 

an injection depth waiver is appropriate. Specifically, the Director must consider whether 

alternative injection sites are available; community needs, demands, and supply from drinking 

water resources; planned needs, potential and/or future use of USDWs and non-USDWs in the 

area; and a plan for securing alternative resources or treating USDW formation waters in the 

event of contamination related to the Class VI injection activity. 

Letter ID: 0142 Comment ID: 22550 Letter Lines: 506 to 511 

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

Comment: Use of commercial proprietary codes should be authorized. Proprietary doesn't 

mean secret. A proprietary code largely vetted by the industry can be the best 

application in many circumstances. To promote peer review and benchmarking, the 

assumptions and theories for all numerical models should be publicly available 

and the solution of any analytic equations used in the predictive process should 

be fully elaborated. 

Individual Response: EPA agrees that available proprietary models may meet the complex 

needs for calculating the AoRs of GS sites, and shares their concern about the need to evaluate 

13
the inputs and assumptions used. EPA will allow the use of proprietary models in meeting the 

requirements for the GS regulation, as long as GS well operators using a proprietary model 

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

scientific basis. EPA adds that its Confidential Business Information requirements at 40 CFR 

144.5 will apply to the use of proprietary models. 

Letter ID: 0142 Comment ID: 22551 Letter Lines: 514 to 570 

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

Comment Code: 3400 2.2.2 Corrective Action 

Comment: Area of Review and Corrective Action 

In the context of carbon storage, NGWA thinks it is important to distinguish 

between the CO2 plume footprint and the zone of elevated pressure. The rationale 

is given in the next section, but the following conditions should be met: 

- No fixed radius can be used, a zone of endangering influence (ZEI) must be 

determined through modeling (but cannot be smaller than 1⁄4 mile in its smallest 

horizontal dimension) 

- In the volume generated by the CO2 plume footprint (plus appropriate buffer) 

(this volume is defined as the "primary AOR"): all penetrations between the base 

of the injection formation and the base of the USDW should be reviewed and any 

necessary corrective action should be taken before start of project. 

- In the elevated pressure area but outside of the CO2 plume footprint (defined 

as the "secondary AOR"), all current penetrations through the primary seal and 

the injection formation should be reviewed. However the applicant should be 

allowed to perform corrective action in a pseudo-concentric phased manner ahead 

of and according to the development of the pressure plume. 

- Secondary AOR/zone of elevated pressure cannot be computed independently of 

other injection projects in the vicinity. The impact of other sequestration 

projects must be included in determining injection rate / period of injection. 

- Primary and secondary AOR must be periodically reviewed to ensure that 

modeling predictions are met. If they are not, the primary and secondary AOR 

should be revisited. The operator should keep track of any new penetration in 

the primary AOR volume and secondary AOR (for example, for oil and gas 

industry). 

"Primary AOR" - Why "Volume of Review" 

Because CO2 is strongly buoyant, it is not sufficient only to investigate 

penetrations in the injection formation and primary seal. The whole volume 

potentially contacted by the CO2 plume should be reviewed. The review and 

14
corrective actions should be performed before the start of injection because 

there is no stopping the CO2 migration once started. The greatest degree of 

effort should be on the deeper wells in the injection zone and primary 

containment then on the secondary containment and seal (if any) and then on 

shallower wells but as many as possible of the shallower wells should be 

compiled too. 

Delayed Corrective Action for "Secondary AOR" 

A simple time-dependent secondary AOR that expands as the volume of injection 

increases and the CO2 migrates is not acceptable. The secondary AOR should be 

agreed upon and reviewed before injection starts but corrective action can be 

somewhat delayed. The secondary AOR consists of only the injection formation and 

seal as used in the current rules because only brine/formation water leakage is 

an issue in the elevated pressure area. The likely presence of a large elevated 

pressure area does not make realistic imposing corrective action on all wells 

before the start of a project. There is no need to provide corrective action to 

wells before the pressure significantly rises. If another problem (e.g., CO2 

leakage) occurs earlier at another location and injection stops, pressure will 

not keep rising and will drop. In addition, delaying corrective action will 

allow taking advantage of technical improvements that will undoubtedly occur in 

the next decades. 

Individual Response: EPA agrees that the AoR for a GS project should incorporate both the 

CO2 plume and the pressure front, and clarifies that the requirements for AoR delineation in the 

final rule incorporate both the CO2 plume and associated pressure front. This area would be 

modeled based on anticipated CO2 volumes to be injected and other site-specific information 

that would impact pressure changes in the subsurface. EPA agrees that both of these should be 

taken into account in determining corrective action needs and developing a testing and 

monitoring plan, and that the requirement to delineate the AoR at §146.84(c) addresses the 

potential risks raised by the commenters. EPA believes that the final GS requirements for 

delineating the AoR provide sufficient protection to USDWs, without introducing an overly 

complex regulatory process. 

EPA acknowledges the commenter’s support of phased corrective action and agrees that phased 

corrective action may provide many benefits to a project including, but not limited to, spreading 

the burden of cost, avoiding delays in project start-up, allowing for use of future, improved 

corrective action techniques and addressing unanticipated changes in the movement of the CO2 

plume or pressure front. EPA believes that the phased corrective action approach is appropriate 

for GS projects, and retained it at 146.84(b)(2)(iv) in the final GS regulation. 

Letter ID: 0142 Comment ID: 22552 Letter Lines: 572 to 588 

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

comment) 

15
Comment: Modeling is Needed: When considering tens of miles, trying to use 

conservatively the analytical solution as provided in 40 CFR §146.06 will likely 

generate unrealistically large AORs. Parameters such as formation thickness and 

heterogeneity, storativity and permeability values will likely vary in the zone 

of elevated pressure suggesting that model results should be accepted as valid. 

How to define the edge of the AOR? If the CO2 plume is relatively easy to 

define in terms of modeling, this is much less true for the pressure plume. 

Limits to the secondary AOR can be defined more or less as it is currently done 

by the contour line of the additional pressure that would push the injection 

formation brine beyond some elevation threshold (for example, 100 ft below the 

base of the USDW). Time-varying area where corrective action needs to take place 

as injection progresses can be defined in a similar fashion. 

AORs can be initially defined solely on the basis of modeling. However, NGWA 

strongly supports that a satisfactory match between prediction and actual field 

measurements needs to be assessed as the project progresses. 

Individual Response: EPA agrees that monitoring and operational data should be used to verify 

that the CO2 plume and pressure front are moving as predicted in AoR calculation models 

(146.84(e)). EPA believes that the requirements for periodic AoR reevaluation can also help 

address uncertainties inherent in predictive modeling and allow for refinement of model 

predictions based on monitoring, operational, and other site-specific data. 

Letter ID: 0142 Comment ID: 22553 Letter Lines: 591 to 676 

Comment Code: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment Code: 4600 2.6 Proposed Plume and Pressure Front Monitoring Requirements (40 

CFR 146.90) 

Comment: Fluid Movement 

The UIC regulations have, from the beginning, included two standards of 

prohibition of fluid movement that may be appropriate for geological 

sequestration of carbon dioxide. The fluid movement requirement for Class I 

injection wells states: 

The well must be constructed, operated, maintained, and plugged such 

that injection activities will not cause movement of any contaminant 

into a USDW 

The fluid movement requirement for Class V injection wells states: 

No owner or operator shall construct, operate, maintain, convert, plug, 

abandon, or conduct any other injection activity in a manner that allows 

the movement of fluid containing any contaminant into underground 

16
sources of drinking water, if the presence of that contaminant may cause 

a violation of any primary drinking water regulation under 40 CFR part 

142 or may otherwise adversely affect the health of persons. The 

applicant for a permit shall have the burden of showing that the 

requirements of this paragraph are met. 

The NGWA recommendation for carbon sequestration well permitting includes an 

experimental phase for each location that will be used for geological 

sequestration of carbon dioxide. Wells constructed during the experimental 

phase at each location will have extensive testing requirements and exploratory 

objectives that will not be needed during the operational phase. It will not be 

necessary or practical to apply the same standard of fluid movement to both the 

experimental phase and the operational phase of carbon sequestration. 

The NGWA recommendations also include early warning monitoring to detect 

movement of fluids containing carbon dioxide or contaminants before the fluids 

reach a USDW. The advantage of early warning monitoring is in the ability to 

detect fluid movement before a drinking water supply is impacted. The 

identification of a geological unit that can serve as secondary containment for 

the injected fluid is addressed in the NGWA recommendations for geologic 

characterization. It is recommended that early warning monitoring be included 

in the requirements for operation of Class V experimental carbon sequestration 

wells, as well as Class VI operational carbon sequestration wells. The 

requirement for early warning monitoring should include authorization for action 

by the regulatory agency when fluid movement is detected by the early warning 

monitoring system. 

Class V Experimental Carbon Sequestration Well: During the experimental phase 

of injection, while the well is permitted as a Class V well, the following fluid 

movement criterion should apply: 

No owner or operator shall construct, operate, maintain, convert, plug, 

abandon, or conduct any other injection activity in a manner that allows 

the movement of fluid containing carbon dioxide or any contaminant into 

underground sources of drinking water, if the presence of carbon dioxide 

or that contaminant may cause a violation of any primary drinking water 

regulation under 40 CFR part 142 or may otherwise adversely affect the 

health of persons. The applicant for a permit shall have the burden of 

showing that the requirements of this paragraph are met. 

Class VI Operational Carbon Sequestration Well: During the operational phase of 

injection, while the well is permitted as a Class VI well, the following fluid 

movement criterion should apply: 

No owner or operator shall construct, operate, maintain, convert, plug, 

abandon, or conduct any other injection activity in a manner that allows 

17
the movement of fluid containing carbon dioxide or any contaminant into 

underground sources of drinking water, if the presence of carbon dioxide 

or that contaminant may cause a violation of any primary drinking water 

regulation under 40 CFR part 142 or may otherwise adversely affect the 

health of persons. Additionally, no owner or operator shall construct, 

operate, maintain, convert, plug, abandon, or conduct any other 

injection activity in a manner that allows the movement of carbon 

dioxide in gaseous phase to land surface, nor limit the extraction of 

drinking water from a underground sources of drinking water by reduction 

of porosity or changes in pH or water quality due to geochemical 

reactions, or by causing a buildup of gas in the underground sources of 

drinking water. The applicant for a permit shall have the burden of 

showing that the requirements of this paragraph are met. 

If any water quality monitoring of an underground source of drinking 

water indicates the movement of any contaminant into the underground 

source of drinking water, or a violation of any part of the preceding 

paragraph, except as authorized under part 146, the Director shall 

publish a notice in newspapers of general circulation in whose service 

area the fluid movement was detected. If a meritorious request is 

submitted by the public, the Director shall prescribe such additional 

requirements for construction, corrective action, operation, monitoring, 

or reporting (including closure of the injection well) as are necessary 

to prevent such movement. 

Individual Response: EPA does not agree that each GS site must first be permitted as an 

experimental Class V well before being authorized to operate a full-scale Class VI well. 

Following the promulgation of the final rule, EPA will allow the use of Class V experimental 

technology permits only for experimental purposes; i.e., to test new, unproven technologies. EPA 

does not consider it appropriate to permit CO2 injection wells that are testing the injectivity or 

appropriateness of an individual formation (e.g., as a prelude to a commercial-scale operation) as 

Class V experimental technology wells. Such wells should be permitted as Class VI wells. 

The final rule at §146.90(g) requires owners or operators 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 pressure monitoring in the injection zone is necessary to track the 

development and movement of the pressure front and CO2 plume. Monitoring can also identify 

needed remedial actions, provide inputs for AoR reevaluation modeling, evaluate predictions of 

plume movement, and target additional geochemical and surface monitoring needs. Knowledge 

of the location of the CO2 plume and the associated pressure front will also assure the public that 

GS projects are proceeding according to plan, provide sufficient information to the owner or 

operator and Director, or allow for appropriate actions to address any indication that USDWs 

18
may be endangered. 

In addition to monitoring to track the movement of the CO2 plume and pressure front, EPA 

believes that monitoring above the confining layer is an important part of a rigorous monitoring 

program and can help detect potential breaches of the confining zone. Such monitoring can 

provide an early warning that the plume or other substances may be approaching a USDW. The 

final rule, at §146.90(d), requires periodic monitoring of the ground water quality and 

geochemical changes above the confining zone(s). Monitoring in additional formations, e.g., the 

injection zone, may also be necessary, and if the Director believes such monitoring is warranted 

he/she has the authority to require that it be included in the testing and monitoring plan. EPA 

adds that the baseline geochemical data required at §146.82(a)(6) will help owners or operators 

interpret the results of this monitoring. 

EPA acknowledges that there are potential risks associated with GS, including the potential for 

leakage of CO2 or other substances into USDWs. However, the purpose of the UIC regulations 

including the Class VI requirements is to protect USDWs from endangerment. In order to protect 

USDWs from endangerment §144.12 prohibits the movement of fluid into USDWs. Consistent 

with §144.12, EPA is finalizing the Class VI requirements in order to ensure that USDWs are 

protected by minimizing and mitigating potential/identified risks through proper site 

characterization, well construction, operation, monitoring, post-injection site care, and site 

closure. The GS rule accomplishes this through requirements tailored to address the unique 

nature of GS, including the large volumes of CO2 injected, its buoyancy and potential corrosivity 

in the presence of water, and impurities in the CO2 stream. Furthermore, if any water quality 

monitoring of a USDW indicates the movement of any contaminant into the underground source 

of drinking water, except as authorized under part §146, the Director shall prescribe such 

additional requirements for construction, corrective action, operation, monitoring, or reporting 

(including closure of the injection well) as are necessary to prevent such movement. 

Letter ID: 0142 Comment ID: 22554 Letter Lines: 679 to 690 

Comment Code: 3820 2.3.1 Well construction procedures 

Comment: Well Construction, Testing, and Closure 

Wells will be an integral part of a CO2 sequestration operation. Wells will be 

used to inject CO2 into the target sequestration formation and monitor the 

sequestration and other formations that could be affected by the injection. 

Because wells represent a potential conduit for CO2 or formation fluids to move 

out of formation and possibly to the surface great care must be taken to 

construct wells such that they will not leak, monitor them to ensure that they 

do not start leaking, and close them to ensure that they do not become a leakage 

risk later. Wells must demonstrate the ability to contain both injected and 

native fluids without allowing significant movement between formations or to the 

surface. 

Individual Response: EPA agrees and believes that appropriately designed and constructed 

19
wells are necessary to prevent endangerment to USDWs and maintain integrity of the well 

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

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

Letter ID: 0142 Comment ID: 22555 Letter Lines: 692 to 701 

Comment Code: 3820 2.3.1 Well construction procedures 

Comment Code: 4600 2.6 Proposed Plume and Pressure Front Monitoring Requirements (40 

CFR 146.90) 

Comment: Construction 

Regardless of the site specific component the new wells will need to be designed 

to meet the overarching goals for all projects. The goals for and injection 

well will be to inject CO2 and to keep fluid from moving along the wellbore 

between formations or to the surface. The goals for a monitoring well are to 

monitor the injection or other formations and also to keep fluids from moving 

along the wellbore. To accomplish these goals the design of the well needs to 

address site-specific, objective-specific (monitoring or injection), and fluidspecific considerations. All injection wells should be cased and cemented to 

Individual Response: EPA agrees that appropriate injection well construction will depend on 

site-specific factors. In determining whether to grant a Class VI permit, the Director will evaluate 

the appropriateness of the proposed injection well construction based on site-specific information 

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

and information about the carbon dioxide stream as provided in §146.86(b)(1). In addition to the 

flexibility given to the owner and operator, Director's discretion is specifically provided in 

§146.86(b)(1) for casing and cementing and §146.86(c)(2 and 3) for tubing and packer location 

and type. 

EPA believes that monitoring using wells in the injection zone (i.e., that penetrate the confining 

zone) can be safely performed if the wells are constructed to prevent flow between the injection 

zone and USDWs or other layers above the confining zone. To mitigate the risk of fluid 

movement, EPA requires owners and operators to submit a testing and monitoring plan that 

describes how the owner or operator plans to site and construct monitoring wells. 

EPA has developed a brief technical paper on construction of monitoring wells that perforate the 

confining zone; this paper can be found in the rulemaking docket. EPA is developing guidance 

on well construction that will include recommendations for monitoring well construction. The 

guidance will be available on EPA’s website at 

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

Letter ID: 0142 Comment ID: 22556 Letter Lines: 701 to 716 ; 1213 to 1214 ; 1280 to 1282 

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

20
Comment Code: 3824 2.3.1.2 Cementing of long-string casing (seeking comment) 

Comment: specific considerations. All injection wells should be cased and cemented to 

stop fluid movement between formations. A surface casing should be installed 

and set below the lowermost USDW above the injection zone and cemented along its 

entire length. It is important when considering the height of the cement sheath 

behind the long-string casing to consider the overall "design" of the injection 

and monitoring zones. Because, it is ideal to have a secondary caprock it will 

be imperative to cement the well, at a minimum, from the injection zone to a 

level above the secondary confining unit. If the borehole through the secondary 

caprock is left uncemented the effectiveness of the secondary caprock will be 

greatly reduced. Furthermore, it may be advisable to cement the casing along 

the entire length to protect the casing from degradation due to anodic 

dissolution [Anstice et al., 2005] or exposure to corrosive formation fluids. 

If the casing is not cemented along its entire length it may be necessary to use 

cathodic protection, depending on the site, to keep the casing from degrading. 

Watson and Bachu, [2007] found that about 81% of wells in their study area that 

had surface casing vent flows (leaks) had them above the top cemented section. 

Anstice, D.J., Page, C.L., and Page, M.M., 2005, "The pore solution phase of 

carbonated cement pastes," Cement and Concrete Research, Vol. 35, pp. 377-383. 

Watson, T.L. and Bachu, S., "Evaluation of the potential for gas and CO2 leakage 

along wellbores," paper SPE 106817 presented at the 2007 E&P Environmental and 

Safety Conference, Galveston, TX, March 5-7, 2007. 

Individual Response: EPA agrees that the casing should be cemented along its entire length. 

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

of the lowermost USDW and be cemented to the surface, and that at least one long string casing 

must be cemented to the surface in one or more stages at §146.86(b)(3). EPA believes that these 

requirements are an important component of construction that will protect USDWs from 

endangerment. 

Cathodic protection can also be used to control corrosion, even when the long-string casing is 

fully cemented. Though not required for all wells, additional techniques like cathodic protection 

may be required by the Director if he/she determines they are necessary at a specific location to 

ensure protection of USDWs. EPA adds that the Director also has the authority to require a 

casing inspection log, as specified at §146.89(d), which can be used to determine the presence or 

absence of corrosion of the long-string casing and can give early warning of casing problems 

with corrosion. 

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. 

21
Letter ID: 0142 Comment ID: 22557 Letter Lines: 718 to 732 

Comment Code: 3820 2.3.1 Well construction procedures 

Comment Code: 4600 2.6 Proposed Plume and Pressure Front Monitoring Requirements (40 

CFR 146.90) 

Comment: The materials used for construction need to be compatible with the injected 

fluid and compatible with the formation fluids. Both injection and monitoring 

wells should be constructed to the same material standard unless there is an 

objective-specific reason not to, because they may both be subjected to similar 

aggressive down-hole conditions. In order to insure that proper wellbore 

construction materials are always selected a standard should be adopted that 

specifies wellbore materials should resist the expected downhole conditions to a 

sufficient degree such that degradation will not lead to leakage. The 

thicknesses of the casing and tubing must be sufficient to handle the pressure 

associated with the injected CO2. Although materials are an important aspect in 

well construction centralization of the casing is also important for insuring 

the cement job is successful. It is very important that the casing is 

centralized over the entire cemented section. This will provide the best 

condition to achieve full radial coverage of the cement between the casing and 

the formation. 

Individual Response: EPA agrees that well materials need to be compatible with injected fluids 

and formation fluids. The GS rule at §146.86(b)(1) requires that all injection well materials be 

compatible with fluids with which the materials may be expected to come into contact. Further, 

the rule, at §146.82(a)(7), requires owners or operators to submit information on planned 

injection pressures, that the Director will use in evaluating the proposed casing, tubing, and 

packer design. EPA adds that, in determining the suitability of well materials and the design of 

the well, the Director must consider various aspects of the injection project, including injection 

pressure, external pressure, internal pressure and axial loading in §146.86(b)(1)(ii), corrosiveness 

of the CO2 stream and formation fluids in §146.86(b)(1)(v). 

EPA requires under §146.90 that owners or operators submit proposed testing and monitoring 

plans to the Director at the time of the permit application. The operator will need to demonstrate 

that the monitoring wells will be constructed and operated in a manner that will be sufficiently 

protective of USDWs from endangerment. Monitoring wells will differ from injection wells in 

their purpose, casing sizes, and depth, although their casing and cementing will likely be similar. 

Unlike injection wells, monitoring wells will not need to be built to withstand CO2 injection, but, 

nonetheless, will need to be built with materials and a design that ensure integrity of the well 

throughout its planned life so that the well does not serve as a conduit for movement of the CO2 

stream or formation fluids. As described above, EPA is developing guidance on testing and 

monitoring at GS sites, which will discuss monitoring well construction. The guidance will be 

available on EPA's web site, at 

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

22
Letter ID: 0142 Comment ID: 22558 Letter Lines: 734 to 739 

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

Comment: For both types of wells, it is important that regulations require that internal 

safety measures are installed in the well. This will help ensure that wells do 

not allow leakage out of the well through the wellbore in the case of an 

accident or other event. Down-hole shutoff equipment needs to be required. The 

shutoff equipment needs to be downhole to avoid leakage if the surface 

components of the well are damaged. 

Individual Response: After evaluating the risks and benefits of down-hole shut-off systems and 

considering additional research, EPA will not require automatic down-hole shut-off devices for 

onshore Class VI wells since it is not necessary in all cases to ensure protection of USDWs from 

endangerment. Instead, the final rule, at §146.88(e)(2), requires that owners or operators of 

onshore Class VI wells install automatic surface shut-off devices. The rule affords Director's 

discretion to mandate automatic down-hole shut-off devices in onshore situations that may 

warrant their use. However, the Agency believes that offshore Class VI wells present unique 

construction and operational conditions, including isolation from shorelines and the need to 

construct wells through the water column and the subsurface, which may delay response time in 

the event of well difficulties. The rule requires, at §146.88(e)(3), that owners or operators of 

offshore wells within State territorial waters install automatic down-hole shut-off systems. EPA 

believes that these requirements at §146.88(e) ensure that proper precautions are taken to prevent 

subsurface fluid movement and ensure protection of USDWs. 

Letter ID: 0142 Comment ID: 22559 Letter Lines: 741 to 748 

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

Comment: In some areas it is likely that existing wells will be converted into both 

injection wells and monitoring wells. It seems unlikely that such wells will 

have been constructed to the same standard as wells purpose-built for 

sequestration applications. This, however, is probably not reason enough to 

rule them out from being used as long as they meet the same standards for 

protection as new wells do. This said, there should be a cutoff date so that 

all wells used for CO2 injection or monitoring constructed after the date are 

constructed to the same standard. 

Individual Response: EPA agrees that converted wells should be subject to Class VI 

requirements. Following conversion of the project to GS, many of the unique factors of GS sites 

(e.g., increased reservoir pressures associated with large volumes of stored CO2 and the 

corrosivity of CO2 in the presence of water) will result in an increased risk profile and warrant 

the specific requirements in the final GS rule. Projects that inject CO2 for the primary purpose of 

long term storage will be permitted as Class VI wells and will be subject to the specific 

requirements in the final GS rule. The GS rule contains tailored requirements that directly 

address issues unique to large-scale CO2 injection for GS. 

23
The final GS rule provides that 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 

reuirements 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). 

EPA does not plan to institute a "cut off" date for this requirement since conversion is a sitespecific decision that may take place at different times then other conversions and it cannot be 

predicted with certainty when all eligible ER fields in the US will have been transitioned for GS. 

EPA encourages owners or operators and Directors to coordinate on re-permitted wells to ensure 

that all wells used for GS are constructed and operated in a manner that protects USDWs from 

endangerment. 

Letter ID: 0142 Comment ID: 22560 Letter Lines: 750 to 754 

Comment Code: 3826 2.3.1.3 Packer requirements (seeking comment) 

Comment: Injection wells should be designed to inject through tubing. Tubing and packer 

allow for monitoring pressure in the annulus between the tubing and casing to 

help identify any leaks. Furthermore the tubing can be replaced relatively 

easily in the case any damage to the tubing is identified or to change the 

diameter of the tubing. 

Individual Response: EPA acknowledges the comment and agrees that the use of tubing and 

packer in accordance with §146.86(c) will offer the best multiple-barrier protection of USDWs 

from endangerment. This requirement is retained in the final GS rule. 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: 0142 Comment ID: 22561 Letter Lines: 757 to 785 

Comment Code: 4500 2.5 Proposed Mechanical Integrity Testing (MIT) Requirements (40 CFR 

146.89) 

Comment: Wellbore Integrity Monitoring and Measurement 

The integrity of monitoring and injection wells must be established and 

monitored. However, the type of integrity measurement(s) should be decided upon 

based on the construction of the well, the well materials, and the effectiveness 

of the monitoring techniques. Wells that are not cemented from total depth (TD) 

to the surface should be subject to more integrity monitoring than those that 

24
are cemented from TD to surface because the path behind the uncemented section 

of casing could act as a fast path for fluids to move between formations. No 

single specific monitoring technique should be required and it is expected that 

multiple techniques will be needed. The deviation of all wells should be 

measured to ensure that the geometry of the well is understood to identify areas 

that may require special attention, like poorly centralized sections, to ensure 

that they are carefully characterized. 

A requirement will be needed to ensure that the integrity and quality of the 

casing and cement job are initially and remain sufficient to prevent fluid 

movement along the wellbore. Because the cement is behind the casing, it will 

be necessary to use some type of logging tool to make the measurement. The 

selection of logging tools should be based on proven performance. The 

prescription of a particular tool may force the use of a technology in the 

future that is not the best available for the job. This said, the standard for 

selection of the tool can be specified and should take into account the geometry 

of a wellbore. Because wells are cylindrical, the integrity and location of the 

cement must be verified using technology capable of radially evaluating and 

mapping the cement, identifying the location of channels or contaminated cement, 

and validating the casing-cement and cement-formation bonds, thus providing a 

360° map of the cement and any potential defects for the entire length of the 

cemented casing. 

Individual Response: 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 agrees with the 

commenter that flexibility to choose appropriate MITs is important, and the GS rule affords this 

flexibility by requiring the owner or operator to prepare and gain approval for a project-specific 

testing and monitoring plan that includes MITs, per §146.90. Owners or operators should 

develop a plan that is appropriate to the well’s design and construction; the Director will evaluate 

the plan based on construction plans submitted with the permit application. 

EPA clarifies that the regulations 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 at §146.89(e). For additional information, please see the 

discussion of MITs in the final rule preamble. 

EPA agrees with the commenter that the integrity and location of the cement must be verified 

using technology capable of radially evaluating and mapping the cement. For this reason, owners 

or operators must, during construction, perform a cement bond and variable density log to 

evaluate cement quality radially, and a temperature log after the casing is set and cemented 

(146.87(a)(2)(ii)). 

In addition, EPA is using an adaptive approach to regulating GS. The Agency plans to collect 

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

25
types of information and appropriate documentation are being collected, and to determine if 

modifications to the requirements are appropriate or necessary. 

Letter ID: 0142 Comment ID: 22562 Letter Lines: 787 to 797 

Comment Code: 4543 2.5.2.1 MIT procedures and methods for GS (seeking comment) 

Comment: Another method of ensuring the mechanical integrity of the well is the use of 

mechanical integrity tests, MITs. MITs, that raise the pressure in the well, 

like the standard annulus pressure test, are often used to measure the internal 

integrity. It is possible that the increase in pressure in the wellbore 

associated with some MITs could damage the interface between the casing and the 

cement possibly creating a leakage pathway. The use of these MITs on CO2 

injection wells should be studied before it is made a requirement. MITs such as 

radioactive tracer surveys, RATS, or other alternative methods with comparable 

results, may be more appropriate for measuring internal integrity. Furthermore, 

RATS and temperature logging may also be an effective technique for identifying 

external wellbore leakage pathways. 

Individual Response: EPA believes that the MITs described in §146.89(c) of the rule (e.g., an 

approved tracer log or temperature or noise logs) are effective methods to demonstrate external 

MI to detect leakage along the wellbore, provide an important early warning of potential 

problems in the injection well system, and represent standard techniques that have been used 

successfully by the drilling industry and the UIC program for many years. 

EPA disagrees that MITs would damage an injection well. Routine MITs are designed to 

measure the sufficiency of the construction of an injection well and to detect subsequent well 

construction, material, and operational problems within the well system before leaks occur. They 

are currently used effectively within the UIC program to ensure MI in other classes of injection 

wells. Damage to a well as a result of a routine, required MIT is unlikely and would be an 

indication of a sub-standard well or a well with some type of construction and/or operational 

defect. Regarding the use of RATS, EPA adds that these are used only in specific circumstances, 

such as in the immediate vicinity of the well perforations/ injection zone. The regulations 

provide the Director flexibility at §146.89(e) to approve the use of alternative MIT methods. 

MITs are a means of measuring the adequacy of the construction of an injection well and a way 

to detect problems within the well system before leaks occur. For additional information, please 

see the discussion of MITs in the final rule preamble. 

Regarding the commenter's recommendation that EPA study MITs on GS wells, EPA clarifies 

that it plans to collect and review data every six years on early GS projects, including MIT data, 

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. 

26
Letter ID: 0142 Comment ID: 22563 Letter Lines: 799 to 801 

Comment Code: 4546 2.5.2.2 MIT frequency (seeking comment) 

Comment: The integrity of the well should be measured on a regular basis such that timelapse comparisons are possible to see if there are changes within the wellbore 

over time that could lead to leakage situations. 

Individual Response: EPA agrees that periodic external mechanical integrity testing is 

justifiable for the protection of USDWs from endangerment, given the unique nature of CO2 GS 

relative to other injection operations, including the potential for corrosion of the injection well 

components (steel casing and cement) and the buoyant nature of the injected CO2 and is 

finalizing regulations that require annual external MITs at §146.89(c). 

Letter ID: 0142 Comment ID: 22564 Letter Lines: 803 to 815 

Comment Code: 5200 2.8.2 Post injection site care (seeking comment) (40 CFR 146.93) 

Comment: Closure 

When all injection operations are finished the site will be closed and the post 

closure period will begin. At this juncture the injection wells will be plugged 

and abandoned. The plugging needs to be done such that the CO2 and formation 

fluids cannot use the wellbore as a conduit when it is complete. No wells 

should be abandoned until there has been a final round of measurements to verify 

the integrity of the well in case remedial action is needed prior to plugging. 

Wells plugged prior to the site closure phase should be plugged and abandoned 

following the same procedures as those in the closure phase. Any requirements 

need to ensure that all wells are properly plugged and abandoned using material 

and methods that will allow the well to remain safe and not become an avenue for 

leakage. 

Individual Response: EPA agrees that Class VI injection wells must be plugged in a manner 

that protects USDWs from endangerment, and believes that the final rule requirements address 

the commenter’s concerns. EPA requires that, to protect human health as it relates to endangered 

USDWs, injection wells be plugged in a manner to ensure that the well will not serve as a 

conduit for future fluid movement into USDWs. In the case of GS wells, the plugging materials 

must be compatible with CO2, as specified at 146.92(b). EPA clarifies that the final GS rule at 

146.92(a) requires owners or operators to perform a final external mechanical integrity test prior 

to the well plugging. These requirements apply whether the well is plugged upon cessation of 

injection or at the time of site closure. 

Letter ID: 0142 Comment ID: 22565 Letter Lines: 818 to 856 

Comment Code: 4600 2.6 Proposed Plume and Pressure Front Monitoring Requirements (40 

27
CFR 146.90) 

Comment: Monitoring, Measurement, and Verification 

Measurement, monitoring, and verification (MMV) will be a key task for all 

geologic carbon sequestration operations. MMV should be looked at as a 

continuation of the measurements that were collected during the characterization 

and construction phases as described in the sections on well construction, 

testing, and closure and geologic characterization. Characterization and 

construction measurements will provide the baseline for comparison during the 

injection and post injection phases of the sequestration project. The data 

collected during the MMV will be used to insure the site is not leaking or for 

the identification and remediation of leaks. The data will also be used to 

calibrate and reduce uncertainty in models of the site. 

During the operational injection phase of a CCS project, MMV can be broken into 

operational monitoring, which is the monitoring of the injected CO2, and 

environmental monitoring, which is the monitoring of the subsurface including 

the sequestered CO2 and the associated pressure front. 

Operational MMV includes; monitoring the volume, flow rate, and composition of 

CO2 that is injected. The injection pressure must be low enough that injection 

does not propagate new fractures and does not open existing faults or fractures 

for flow through the caprock or damage the containment properties of the 

injection well. The operational monitoring will also have to monitor the 

injection and monitoring wells to ensure they are functioning properly and not 

allowing any leakage. The integrity of the injection well must be monitored 

internally and externally to ensure that there is no degradation that could 

allow CO2 to leave the target formation. Well integrity monitoring through the 

use of logs, annulus pressure monitoring, and mechanical integrity tests is 

covered in detail in the section on well construction, monitoring and 

abandonment. 

Environmental MMV needs to be implemented to collect data from the four or more 

geologic formations that comprise the subsurface site: the storage formation, 

the primary cap rock, the monitoring formation, and the secondary cap rock. MMV 

must also provide information on shallow formations, including the lowermost 

USDW, that contain drinking water, the surface and, any potential leakage 

pathways between the storage formation or monitoring formation and any drinking 

water formations or the surface (this may include additional monitoring of wells 

above what is required for operational monitoring). 

Individual Response: EPA agrees that multi-faceted monitoring, as described by the 

commenter, is a key element of ensuring that USDWs are protected from endangerment. The GS 

rule, at §146.90, requires injectate monitoring, mechanical integrity testing, corrosion 

monitoring, tracking the CO2 plume and area of elevated pressure, monitoring geochemical 

28
changes above the confining zone, and, at the discretion of the Director, surface air and soil gas 

monitoring for CO2 fluctuations, and any additional tests necessary to ensure USDW protection 

from endangerment. EPA also agrees with the commenter that data collected during site 

characterization (such as baseline geochemistry, pre-injection reservoir pressure, etc.) are 

appropriate to ensure that baseline information is available to form the basis for comparison 

during GS operation and post-injection. For example, the baseline geochemical information will 

allow the owner or operator and permitting authority to evaluate monitoring data and identify 

any changes in subsurface geochemistry that may indicate fluid movement. 

EPA agrees that the ground water geochemical monitoring outlined in §146.90(d) will maximize 

protection of USDWs from endangerment at GS sites. Direct geochemical sampling is an 

important part of a monitoring program. EPA agrees that direct monitoring for ground water 

quality above the confining zone is important, and the GS rule requires this at §146.90(d). 

Monitoring in additional formations, e.g., the injection zone, may also be necessary, and if the 

Director believes such monitoring is warranted he/she has the authority to require that it be 

included in the testing and monitoring plan. 

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. In addition, in 

January 2009, DOE published a best practices manual entitled "Monitoring, Verification, and 

Accounting of CO2 Stored in Deep Geologic Formations" (DOE/NETL-311/081508); this 

manual is included in the docket for the final GS rule. 

Letter ID: 0142 Comment ID: 22566 Letter Lines: 858 to 873 

Comment Code: 4650 2.6.5 CO2 plume and pressure front tracking (seeking comment) 

Comment: In the injection zone, monitoring must identify the location of the injected CO2 

and the associated pressure front. MMV in the monitoring zone should be geared 

to ensure that any vertical migration across the cap rock is identified. 

Monitoring of USDWs should be set up to look for changes that would be 

associated with the presence of CO2 or CO2-displaced brine. While some general 

monitoring points in all of these zones will be needed, it may be more practical 

to locate monitoring points or take measurements near locations identified 

during the characterization and potential fast-paths, such as abandoned wells, 

existing wells, or faults and fractures. One location that may provide the best 

use of monitoring resources is near the injection well. This is the most likely 

location for upward fluid movement without specific knowledge of a potential 

leakage pathway. Leakage could occur either through mechanical integrity failure 

or defects, or failure or defects of the confining units. Monitoring, in the 

29
monitoring zone and lowest USDW in addition to the injection zone, provides a 

vertical pressure profile, measures stress on the confining units, and may 

detect water quality changes. 

Individual Response: EPA agrees that multi-faceted monitoring is appropriate at GS sites. 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 also required unless the 

Director determines, based on site-specific geology, that such methods are not appropriate. 

EPA believes that pressure monitoring in the injection zone is necessary to track the 

development and movement of the pressure front and CO2 plume. Monitoring can also identify 

needed remedial actions, provide inputs for AoR reevaluation modeling, evaluate predictions of 

plume movement, and target additional geochemical and surface monitoring needs. Knowledge 

of the location of the CO2 plume and the associated pressure front will also assure the public that 

GS projects are proceeding according to plan, provide sufficient information to the owner or 

operator and Director, or allow for appropriate actions to address any indication that USDWs 

may be endangered. 

EPA also believes that direct monitoring for ground water quality above the confining zone is 

important, and the GS rule requires this at §146.90(d). Monitoring in additional formations, e.g., 

the injection zone, may also be necessary, and if the Director believes such monitoring is 

warranted he/she has the authority to require that it be included in the testing and monitoring 

plan. 

EPA believes 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. 

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: 0142 Comment ID: 22567 Letter Lines: 875 to 879 

Comment Code: 4660 2.6.6 Geochemical monitoring 

Comment: In the monitored zones, geochemical and fluid chemical information should be 

based on constituents identified in the characterization as likely indicators of 

leakage. These indicators will likely include the pH and also be identified in 

30
the major and minor chemical constituents of the formation and ionic 

constituents of the formation-fluid. 

Individual Response: While each monitoring plan must be site-specific based on data collected 

during the initial site characterization and baseline geochemical monitoring, it is likely that 

geochemical sampling might include basic water quality parameters such as pH, specific 

conductivity, temperature, CO2, alkalinity, major ions, and select heavy metals. Additional 

parameters may be monitored based on the potential for leaching of minerals or the geochemistry 

of native fluids. 

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: 0142 Comment ID: 22568 Letter Lines: 881 to 901 ; 1224 to 1226 ; 1246 to 1248 ; 

1284 to 1287 

Comment Code: 4655 2.6.5.1 Plume tracking techniques/geophysical methods (seeking 

comment) 

Comment: The methods used for monitoring on projects to date have included time-lapse 

seismic, passive seismic, pressure logging, temperature logging, neutron 

saturation logging, fluid sampling, air sampling [IPCC, 2005]. While it is 

probably not appropriate to specify the suite of MMV tools to be used at every 

site, because not all tools will work at all sites, it is important to emphasize 

that multiple MMV technologies will be required at every site in order to 

completely monitor and collect the necessary data to verify that the site is 

operating within the bounds of its permit. Although it seems unreasonable to 

specify all MMV technologies, it does seem reasonable to specify that monitoring 

wells be installed to collect the necessary fluid samples, pH, resistivity, and 

pressure data. Also, although seismic monitoring may not work everywhere, in 

locations where it is expected to work it should be incorporated into the 

monitoring scheme. Seismic monitoring for CO2 plume location has been 

successfully employed in early projects including Sliepner storage project, 

Weyburn storage project, and Frio brine project [IPCC, 2005, Wilson and Monea, 

2005, Daley et al., 2007]. The data collected from monitoring should be used to 

update and verify the site’s performance and risk models. 

In addition, to aid in selecting other MMV technologies, the International 

Energy Agency has developed a comprehensive database that can be accessed at: 

http://www.co2captureandstorage.info/co2tool_v2.1beta/index.php 

31
Daley, T.M., Solbau, R.D., Ajo-Franklin, J.B., and Benson, S.M., 2007, 

"Continuous active-source seismic monitoring of CO2 in a brine aquifer," 

Geophysics, Vol. 72, No. 5, pp. A57-A61. 

Intergovernmental Panel on Climate Change, 2005, IPCC special report on carbon 

capture and storage, United Nations Framework Convention on Climate Change, ISBN 

92-9169-119-4. 

Wilson, M. and Monea, M., 2005, IEA GHG Weyburn Monitoring and Storage Project, 

Summary Report, 2000-2004, Petroleum Technology Research Center, Regina SK, 

Canada, Proceedings of the 7th International Conference on Greenhouse Gas 

Control Technologies (GHGT-7), Vol. III, September 5-9, Vancouver, Canada 

Individual Response: EPA clarifies that the specifics of monitoring, including the number of 

monitoring wells, must be described in the site-specific testing and monitoring plan, which 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: 0142 Comment ID: 22569 Letter Lines: 903 to 910 ; 1253 to 1257 

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

(seeking comment) 

Comment Code: 4670 2.6.7 Surface air monitoring and/or soil gas monitoring (seeking 

comment) 

Comment: Although surface monitoring may be needed from a community outreach and 

environmental safety point of view, it is important to note that by the time any 

leakage is detected at the surface it will have already passed by and possibly 

impacted underground drinking waters. Projects like the Frio brine project 

[McCallum et al, 2005] have incorporated tracers as a way to identify CO2 

leakage. The use of non-isotopic tracers, tracers other than C13, C14, and O18 

that occur naturally in CO2, should be studied very carefully for unintended 

environmental effects prior to implementation. 

McCallum, S.D., Riestenberg, D.E., Cole, D.R., Freifeld, B.M., Trautz, R.C., 

Havorka, S.D., and Phelps, T.J., 2005, "Monitoring geologically sequestered CO2 

during the Frio brine pilot test using perfluorocarbon tracers," Proceedings of 

the 4th Annual Conference on Carbon Capture and Sequestration, May 2-5, 2005, 

Monitor and Exchange Publications and Forum, Washington, D.C. 

32
Individual Response: EPA clarifies that subsurface geochemical and pressure monitoring in the 

subsurface formations are the first line of monitoring that would allow detection of potential 

endangerment to USDWs from GS activities (this is required at all GS sites, as described at 

§146.90(d)). The Agency also believes that surface air and soil gas monitoring, when coupled 

with subsurface monitoring, may be appropriate at some GS projects to ensure USDW 

protection. EPA acknowledges that surface air and soil gas monitoring may not be suitable in all 

settings as a method to ensure USDW protection. However, EPA does not believe that this 

should entirely preclude their use. The decision to use surface monitoring and the selection of 

monitoring methods will be site-specific (e.g., may be influenced by geology, injection depth, 

and operational conditions) and must be based on potential risks to USDWs within the AoR. 

If surface monitoring were the only monitoring method employed to ensure USDW protection, 

direct correlation of CO2 at the surface with CO2 in the subsurface might be difficult; however, 

when combined with information gathered through other monitoring techniques required of GS 

well owners and operators (e.g., monitoring wells, geophysical techniques), air and soil gas 

monitoring may provide valuable data on the magnitude and location of a leak. The CO2 itself 

may serve as a tracer in the form of stable isotopes of carbon. For example, anthropogenic CO2 

is depleted in 13C compared to naturally occurring CO2. 

The final rule at §146.90(h) retains the allowance for surface air and soil gas monitoring at the 

discretion of the Director as a means of identifying leaks that may pose a risk to USDWs and 

informing emergency notification of a Class VI owner or operator and UIC Director in the event 

of a USDW endangerment, pursuant to requirements at §146.91(c). 

EPA believes that, in some circumstances, tracers can be an important component of a 

multifaceted approach to monitoring GS projects. However, the Agency recognizes that tracers 

may not be appropriate in all GS projects. For this reason, EPA does not require the use of 

tracers at all GS sites; however, 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. 

Letter ID: 0142 Comment ID: 22570 Letter Lines: 912 to 916 

Comment Code: 5100 2.8.1 Injection well plugging activities (seeking comment) (40 CFR 

146.92) 

Comment: Once injection ceases permanently, the operational portion of MMV can also 

cease. This period, called the closure period, is the time in which the 

operator will plug and abandon all wells that will not be used for further 

monitoring. Environmental MMV operations should continue throughout this period 

using the same suite of techniques as in the operational phase. 

Individual Response: EPA clarifies that, following plugging of the injection well and until site 

closure is authorized, owners or operators of GS wells must perform monitoring and provide 

post-injection site care as specified in the post-injection site care and site closure plan for at least 

33
50 years or for the duration of the alternative timeframe approved by the Director pursuant to 

requirements in §146.93(c), unless the owner or operator can make a demonstration earlier that 

the geologic sequestration project no longer poses a risk of endangerment to USDWs. 

Letter ID: 0142 Comment ID: 22571 Letter Lines: 918 to 935 

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

Comment Code: 4650 2.6.5 CO2 plume and pressure front tracking (seeking comment) 

Comment: MMV should be conducted hand-in-hand with modeling over the entire period that 

MMV is occurring, with each new round of measurements being incorporated into a 

new iteration of the appropriate site models. An iterative measurement-modeling 

approach will allow for the best understanding of the shape and size of the AoR. 

It will also help identify areas of uncertainty in the model that may be reduced 

with changes in the MMV plan. Changes identified in the size of the AoR and for 

risk of leakage will help ensure that MMV is carried out at the right frequency 

and in the right locations. The timing of the MMV operations should be flexible 

and adjustable based on the performance of the site and the site models. It is 

likely that the site data from early in the operation will probably be more 

valuable than data from later in the operation for assessing the performance of 

the site and identifying and reducing uncertainties. MMV operations that are 

not continuous should be conducted more frequently at the start of the 

operational phase and then be allowed to become less frequent if the site is 

performing safely and in concert with the model predictions. The initial, more 

frequent monitoring should be specified in the permit as an experimental phase 

of the injection project. The continuation of injection should be contingent 

upon successful containment of the injected CO2 during the experimental phase. 

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 agrees that monitoring data should be used to review model assumptions, verify 

computational model projections, and, when necessary, provide input for model refinements. As 

data are collected at an injection site, model parameters can be adjusted to match observations 

(i.e., for model calibration), which in turn improves the predictive capability of the model. As a 

GS project proceeds, both monitoring and modeling will evolve, with monitoring results 

supporting effective AoR reevaluations and leading to improved model predictions. 

As described above, EPA does not agree that each GS site should have to be permitted as a Class 

V experimental technology well before being authorized to operate as a full-scale Class VI well. 

EPA does not consider it appropriate to permit CO2 injection wells that are testing the injectivity 

or appropriateness of an individual formation (e.g., as a prelude to a commercial-scale operation) 

as Class V experimental technology wells. Such wells should be permitted as Class VI wells. 

34
EPA clarifies that some monitoring frequencies are specified in §146.90; others will be 

established in the monitoring and testing plan submitted with the permit application under 

§146.90. The Director may require changes in the frequencies when the plan is updated, as is 

required at least every 5 years (or when there are changes to the facility or at the request of 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: 0142 Comment ID: 22572 Letter Lines: 937 to 958 

Comment Code: 4650 2.6.5 CO2 plume and pressure front tracking (seeking comment) 

Comment Code: 5460 2.9.2 Comments on transfer of liability for long-term care 

Comment: As the pressure in the injection zone starts to stabilize it may be possible to 

lengthen the period between measurements if the reservoir is performing as 

expected based on the calibrated site models. When the location of the CO2 

either stops changing or can be predicted and validated against measurements 

over multiple measurement cycles, the ownership of the site and the 

responsibility for future MMV, if deemed necessary, may be transferred from the 

operator to the government, starting the post-closure phase. If the site is not 

behaving as expected, an iterative MMV-modeling approach will help identify 

areas of uncertainty that can be reduced by changes in the MMV plan to collect 

more or different data to determine the site’s performance. 

Regulations for the operational phase need to ensure that a licensed Carbon 

Capture and Storage (CCS) site is operated safely and should allow for 

flexibility in the monitoring schedule based on the performance of the site and 

site models. A site that is performing well probably requires less frequent 

monitoring than one that is not performing well. A long-term match between MMV 

data and site modeling results probably indicates a good understanding of the 

site and should be one of the criteria used to decide when the custodianship of 

the site should be transferred from the operator to the government. It is 

possible that iterative MMV and modeling will show that the AoR changes over 

time. The idea of a variable AoR should be included and accepted in any 

regulations. The results of the MMV and modeling including the integrity of the 

Individual Response: EPA clarifies that once injection is complete, the owner or operator must 

monitor as specified in the post-injection site care and site closure plan for at least 50 years (the 

35
Director may require longer if necessary to ensure USDW protection) or for the duration of the 

alternative timeframe approved by the Director pursuant to the requirements at §146.93(b), 

unless the owner or operator can make a demonstration earlier that the geologic sequestration 

project no longer poses a risk of endangerment to USDWs. 

As described above, EPA agrees that monitoring data should be used to review model 

assumptions, verify computational model projections, and, when necessary, provide input for 

model refinements. As data are collected at an injection site, model parameters can be adjusted to 

match observations (i.e., for model calibration or), which in turn improves the predictive 

capability of the model. As a GS project proceeds, both monitoring and modeling will evolve, 

with monitoring results supporting effective AoR reevaluations and leading to improved model 

predictions. 

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. 

Regarding transfer of responsibility following site closure, please note that EPA does not have 

authority to transfer SDWA or other legal liability for Class VI wells to the State or federal 

government or a third-party fund. Under the final GS rule, once an owner or operator has met all 

regulatory requirements under Part 146 for Class VI wells and the Director has approved site 

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

subject to enforcement for regulatory noncompliance. Furthermore, the financial instrument 

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

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

(including violation of 40 CFR 144.12) in certain circumstances. For example, an owner or 

operator may be held liable for regulatory noncompliance even after site closure was approved if 

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

owner or operator when approving site closure. 

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

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

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

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

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

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

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

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

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

which such violation occurs or failure to comply continues. 

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

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

36
§§ 7401-7671; CERCLA, 42 U.S.C. § 9601-9675; and RCRA, 42 U.S.C. § 6901-6992. See the 

final rule preamble for further discussion of EPA's final approach. 

Letter ID: 0142 Comment ID: 22573 Letter Lines: 958 to 961 

Comment Code: 4760 2.7.6 Proposed reporting frequency (seeking comment) 

Comment: regulations. The results of the MMV and modeling including the integrity of the 

wells, fluid properties and volumes, subsurface location of the plume, leakage 

monitoring, modeling, and size of the AoR should be reported at least annually 

or upon a sudden significant change. 

Individual Response: EPA is retaining the requirement at §146.91(a) for semi-annual reporting 

of monitoring and operational data. External mechanical integrity testing, which must be 

conducted annually, must be reported within 30 days of the test. EPA clarifies that some 

monitoring frequencies (e.g., associated with ground water monitoring and plume tracking) will 

be established in the approved testing and monitoring plan, which will be incorporated as a 

condition of the Class VI permit. The frequency of these tests will be determined based on sitespecific information. 

EPA clarifies the final rule includes a requirement at §146.91(c) that operators report within 24 

hours of any event that may endanger USDWs; any leakage that endangers a USDW would be 

addressed in this requirement. 

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: 0142 Comment ID: 22574 Letter Lines: 964 to 1006 ; 1228 to 1234 ; 1240 to 1244 

; 1294 to 1298 

Comment Code: 5400 2.9 Proposed Financial Responsibility and Long-Term Care 

Requirements 

Comment: Overview of Financial Responsibility Issues 

Introduction 

Applying financial responsibility for the various operational and post-closure 

risks is central to widespread deployment of CCS as an effective climate-change 

mitigation strategy. The commonly perceived CCS categories of risks include 

toxicological effects, induced seismicity, subsurface trespass, and climate 

effects (de Figueiredo et al., 2006). The mechanisms for these risks include CO2 

gas leakage from the injection wellhead; gas leakage from geologic reservoir; 

development of injection-related seismicity in existing seismically active 

areas; and, degradation of drinking water aquifers by mobilization of brines or 

37
by geochemical interaction of fugitive CO2 with overlying aquifers. 

These liabilities may be further categorized in terms of operational liability 

and post-injection liability (e.g., Figueiredo et al., 2006). Operational 

liability includes the environmental, health and safety risks associated with 

capture, transportation and injection of CO2. Post-injection liability is 

related to storage of carbon dioxide in the geologic formation after it has been 

injected. According to Figueiredo et al., post-injection liability can be 

further divided according to (1) in situ liability of harm to human health, the 

environment, and property, including degradation of aquifers, and (2) climate 

liability related to leakage of CO2 from the geologic reservoirs and its longterm effect on climate change. 

The long period and geographic scale over which these liabilities can occur pose 

unique challenges for assessing CCS liability, in comparison to conventional 

business liability models. For example, the operational phase of individual CCS 

projects is anticipated to be tens of years (Gerard and Wilson, 2008). Although 

the post-injection risks are inferred to decrease with time, the long period 

over which these risks may manifest themselves and the inherent geophysical 

uncertainties of geologic reservoirs are not amenable to a strictly private 

solution to liability. For example, several authors (e.g., Figueredo et al., 

2006; Edison Electric Institute, 2007; WRI, 2006; and Gerard and Wilson, 2008) 

have suggested that the unique liabilities associated with CCS should be 

assigned to the operators during the injection phase and for a short period 

after cessation of injection and closure of the injection wells, and the longterm post-closure liability should become a public responsibility because of the 

perceived significant public benefit that CCS will have on local and global 

climate. Another reason to involve the public sector in the long-term liability 

may be to ensure that a responsible entity will be around (i.e., should the CCS 

operator or holding company become insolvent) to address post-closure CCS 

problems, should they arise (World Resources Institute, 2007). 

Edison Electric Institute, 2007, Status and Outlook for Carbon Capture and 

Storage Technology in the United States. Written statement for the U.S. House 

Select Committee on Energy and Global Warming. 

Figueiredo, M. de, D. Reiner, H. Herzog, and K. Oye, 2006 The Liability of 

Carbon Dioxide Storage. Presented at the Eight International Conference on 

Greenhouse Gas Control Technologies, Trondheim, Norway 

Gerard, D., and E.J. Wilson, 2008, Environmental Bonds and the Problem of LongTerm Carbon Sequestration. Source. Journal of Environmental Management, In 

Press. Available online as of July 2008: 

http://www.epp.cmu.edu/csir/Content/Research/Carbon%20Capture%20and%20Sequestrat 

ion/Gerard%20Wilson%20Bonding.doc 

38
World Resources Institute, 2007, Workshop Summary: Addressing Long-Term 

Liability of Carbon Dioxide Capture and Geologic Sequestration. 

World Resources Institute, 2006, Executive Summary: WRI Workshop on CCS 

Liability. 

Individual Response: EPA agrees that assuring financial responsibility throughout the lifetime 

of a GS project, i.e., for corrective action on wells in the AoR, injection well plugging, PISC and 

site closure, and emergency and remedial response, is an important component of ensuring that 

USDWs are protected. The goal of financial responsibility is to ensure that financial resources 

are available to prevent endangerment of USDWs from improper plugging, remediation, and 

management of wells in the event that the owner or operator experiences financial difficulties. 

Please see the discussion of EPA's final regulatory approach in the preamble to the final GS rule 

for additional information on how the GS requirements address the unique risks associated with 

GS projects. 

Under SDWA authority, owners or operators of injection wells must ensure protection of 

USDWs from endangerment and are subject to liability for enforcement under the Act. 

The final rule requires that an owner or operator must conduct monitoring as specified in the 

Director-approved PISC and site closure plan following the cessation of injection until the owner 

or operator can demonstrate to the Director that the geologic sequestration project no longer 

poses an endangerment to USDWs. For additional information about the PISC and site closure 

requirements, see the preamble to the final GS rule. 

Once an owner or operator has met all regulatory requirements under Part 146 for Class VI wells 

and the Director has approved site closure pursuant to requirements at §146.93, the owner or 

operator will generally no longer be subject to enforcement for regulatory noncompliance. 

Furthermore, their financial instrument as required under §146.85 will be released if it was not 

used. However, even if a site closure is approved under §146.93, an owner or operator may be 

held liable for regulatory noncompliance (including violation of 40 CFR 144.12) in certain 

circumstances. For example, an owner or operator may be held liable for regulatory 

noncompliance even after site closure was approved if the Director relied on erroneous 

information (e.g., erroneous modeling data) provided by the owner or operator when approving 

site closure. 

Additionally, an owner or operator may always be subject to any action the Administrator deems 

necessary to protect the health of persons under §1431 of the SDWA after site closure if there is 

unanticipated migration towards or into a USDW that causes or threatens imminent and 

substantial endangerment to public health. The action may include issuing administrative orders 

or commencing a civil action for appropriate relief. If the owner or operator fails to comply with 

the order, they may be subject to a civil penalty for each day in which such violation occurs or 

failure to comply continues. 

The Agency clarifies that Class VI well permits may be transferred to another owner or operator 

39
pursuant to §144.38 whereby generally all other regulatory responsibilities are transferred to that 

new owner and operator, which includes all potential liabilities associated with meeting the 

requirements of that permit. Please see further clarification on the issue of long term liability in 

the preamble of the final rule. 

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

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

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

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

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

EPA's final approach. 

Letter ID: 0142 Comment ID: 22575 Letter Lines: 1008 to 1158 ; 1216 to 1218 ; 1240 to 1244 

; 1262 to 1274 ; 1289 to 1292 

Comment Code: 5460 2.9.2 Comments on transfer of liability for long-term care 

Comment: Applicable and Relevant Liability Models 

Public health/environmental liability models currently exist in North America 

that may to offer some insights to help develop workable CCS liability policy to 

safeguard public interests yet remain attractive to private/corporate investors 

who will help fund development of the required CCS technology and large-scale 

CCS operations. 

Alberta Acid Gas Re-Injection. Acid gas streams, consisting primarily of 

hydrogen sulfide and carbon dioxide, are commonly generated as a by-product of 

the gas "sweetening" process used to bring produced natural gases and solution 

gases up to pipeline specifications for sales and transport. Prior to 

introduction of acid gas re-injection, treatment of acid gases included flaring. 

The province of Alberta has over 38 acid gas re-injection wells in operation 

(Wong et al., 2003). In Alberta, the injection well operator is financially 

responsible (liable) for operation and closure of acid gas re-injection wells, 

but there is no responsibility for post-closure monitoring or mitigation of gas 

leaks, whether leakage is from the storage reservoir or from the closed 

injection well (Bachu, 2007). In addition, there is no provision to ensure that 

"orphaned" (abandoned) re-injection wells are closed properly by a public or 

private entity, should the operator becoming insolvent. 

Price-Anderson Act. The Price-Anderson Act was passed as federal law in the 

United States in 1957 to partially indemnify the nuclear industry against 

liability claims for nuclear incidents while still protecting the general 

public. The Act established a no-fault insurance fund in which the first $10 

billion of an incident claim is funded by industry and the federal government 

covers the remainder over this amount. The federal government instituted this 

Act to provide an incentive for private investment in nuclear power; without 

40
this type of indemnification, investors were unwilling to accept the 

unquanitifed risks of nuclear energy. Although criticized by some groups , the 

Act has been renewed several times and is currently set to expire in 2025. The 

Act appears to focus primarily on liability for nuclear plant operation and not 

for post-closure incidents. Over the first 43 years of operation until 2000, the 

secondary federal insurance has not been required. The nuclear industry has paid 

a total of $151 million to cover claims, including $70 million for the Three 

Mile Island incident. During the same period, the Department of Energy has paid 

about $65 million to cover claims for its own nuclear operations. 

Resource Conservation and Recovery Act (RCRA). Enacted by the U.S. Congress in 

1976, RCRA mandates that companies set aside funds for post-closure care of 

solid and hazardous waste sites, and establishes EPA’s authority to control 

related wastes from "cradle-to-grave" (USEPA(a), downloaded 2008). For example, 

solid waste landfill operators in most U.S. states bear financial responsibility 

for public health and safety, environmental health, environmental monitoring, 

landfill maintenance, and remediation/treatment of leachate and contaminated 

ground water during landfill operation and for a post-closure period. Financial 

assurance of ability to cover these costs is generally required as a condition 

of the operator’s state permit for both the operating and post-closure period. 

Some states (e.g., Maine) require that the financial assurance cost estimates be 

based on the entire expected time that the solid waste facility is expected to 

be generating leachate, landfill gases and other contaminants that have a 

potential for creating an adverse environmental impact. Pennsylvania bases 

bonding estimates on a 30-year post-closure period, but final closure is 

performance-based and site specific; upon final closure determination, a 10-year 

bond liability period commences. However, the operator and landowner are still 

liable beyond this period for adverse effects and other changes in site 

conditions. Other states require post-closure monitoring, remediation and 

financial assurance for a finite period (e.g., Ohio - 30 years; Vermont - 20 

years). 

In 1986, Congress created a Leaking Underground Storage Tank (LUST) Trust Fund 

by amending Subtitle I of RCRA. The LUST Trust Fund provides money for 

overseeing and enforcing corrective action by a responsible party, and for 

cleanup at UST sites where the owner is unknown, unable, or unwilling to respond 

(USEPA(b), downloaded 2008). The Trust Fund is financed by a 0.1 cent tax on 

each gallon of motor fuel. All 50 states have cooperative agreements with EPA to 

spend this money for LUST-related activities. In addition, 47 states have 

established state-run LUST Funds to help owners and operators with UST upgrades 

and LUST remediation problems (Tiemann, 1999). Reimbursements from the state 

LUST Funds have generally benefited most UST owners/operators who comply with 

the existing state and federal UST regulations, regardless of financial ability 

to cover these costs. Like the RCRA LUST Trust Fund, the state LUST Funds are 

generated through gas taxes and tank fees. 

41
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). 

CERCLA (also referred to as Superfund), enacted by the U.S. Congress in 1980, 

established a tax on the chemical and petroleum industries to finance a fund 

that addresses the liabilities arising from the clean up of hazardous waste 

sites. Over a period of five years, $1.6 billion was collected and the tax went 

into a trust fund for cleaning up abandoned or uncontrolled hazardous waste 

sites (USEPA(c), downloaded 2008). CERCLA was amended in 1986 by the Superfund 

Amendments and Reauthorization Act (SARA). SARA increased the size of the trust 

fund to $8.5 billion (USEPA(d), downloaded 2008). While RCRA was intended to be 

forward-looking, CERCLA is intended to be backward-looking, i.e., contamination 

that occurred prior to RCRA authorization. 

Tiered Approach 

A key tenet of environmental laws and regulations is that pollution costs should 

e borne by their creators. U.S. environmental laws and regulations give this 

principle form by making polluters liable for property, health, and natural 

resource damages and unperformed resource reclamation obligations (Boyd, 2001). 

However, the anticipated great public benefit from CCS implementation and 

reluctance of private investors to become involved in an enterprise that may 

have several hundred years of post-closure liability suggest that a shared 

private/public liability model may be appropriate for long-term post-closure 

phase of CCS. 

Gerard and Wilson (2008) provide a temporally-tiered approach to managing 

liability for all phases of CCS. This approach relies on operator liability and 

use of operator-funded bonds to cover liability during the operational phase 

(Phase 1) of CCS. Gerard and Wilson report that this approach has been used 

effectively for many oil and gas wells and wells regulated under the UIC Program 

where the operational lifetime of the wells is tens of years. This surety 

mechanism and time frame may also encourage proper site management and well 

closure for CCS wells. Short-term post-closure liability (Phase 2) for 

unanticipated accidents would rest with the operator, but active bonding by the 

operator would cease. Monitoring and verification during Phase 2 would be 

financed by publicly run or pooled financial mechanisms that would be funded by 

operator/industry contributions during the active injection phase of the 

project. The third phase of liability and management (Phase 3) would be a public 

responsibility, ensuring that long-term standards of care are met. 

According to Gerard and Wilson, demarcation of the Phase 2 to Phase 3 transition 

could be performance-based (e.g., based on pressure levels in the CCS reservoir 

or on dissolved CO2 in the formation fluid), or prescriptive (e.g., after a 

finite period [10 years, 25 years, etc.]). By Phase 3, project performance and 

success are more certain and public "liability" and management would be viewed 

as primarily administration and record-keeping. 

42
USEPA’s Proposed UIC CCS Rule 

In the proposed UIC CCS Rule, USEPA is proposing a combination of fixed 

timeframe and a performance standard. Post-injection site care (monitoring) 

would occur for a period of 50 years. This period could be shortened or 

lengthened based on plume behavior. If monitoring data demonstrate that the 

plume/pressure front is stabilized and the CO2 injectate does not pose risk to 

USDWs, the 50-year post-injection site care period could be shortened. 

Conversely, if the plume/pressure front has not stabilized after 50 years of 

post-injection monitoring, USEPA would extend the monitoring period until 

stabilization is achieved. 

Conclusion 

It is apparent that much work and public-private sector discussions are needed 

to develop a liability policy framework and details that are workable and 

acceptable to all parties. In recognition of this, USEPA is requesting public 

comments on their proposed 50-year monitoring period with a performance 

element. Developing effective performance-based criteria upon which to base 

transfer of post-closure liability to the public appears to be an area that 

warrants considerable technical research. This transition mechanism could become 

one of the key issues to gain public acceptance for CCS. 

The Task Force recommends that federal and energy industry funding for CCS 

research be directed toward establishing performance-based indicators for CO2 

reservoir stability to facilitate liability transfer. This tiered approach may 

offer ample incentives to ensure that CCS operations are managed responsibly, 

yet not discourage investors from supporting CCS. Public assumption of Phase 3 

liability after the CCS reservoir stabilizes appears commensurate with the great 

public benefit that CCS offers. 

Bachu, S., 2007, Legal and Regulatory Aspects of CCS, in Workshop on Capacity 

Building for Emerging Economies. Carbon Sequestration Leadership Forum in Porto 

Alegre, Brazil. 

Gerard, D., and E.J. Wilson, 2008, Environmental Bonds and the Problem of LongTerm Carbon Sequestration. Source. Journal of Environmental Management, In 

Press. Available online as of July 2008: 

http://www.epp.cmu.edu/csir/Content/Research/Carbon%20Capture%20and%20Sequestrat 

ion/Gerard%20Wilson%20Bonding.doc 

Tiemann, M., 1999, Leaking Underground Storage Tank Issues. CRS Report: 97-471. 

USEPA(a), downloaded 6/29/08. Summary of the Resource Conservation and Recovery 

Act. http://www.epa.gov/lawregs/laws/rcra.htm 

43
USEPA(b), downloaded 6/29/08. Leaking Underground Storage Tank (LUST) Trust 

Fund. http:www.epa.gov/oust/ltffacts.htm 

USEPA(c), downloaded 6/29/08. CERCLA Overview. 

http://www.superfund/policy/cercla.htm 

USEPA(d) download 10/28/08, SARA Overview 

http://www.epa.gov/superfund/policy/sara.htm 

Wong, S., D. Keith, E. Wichert, W. Gunter1and T. McCann, 2003, Economics of Acid 

Gas Reinjection: An Innovative CO2 Storage Opportunity. In Greenhouse Gas 

Control Technologies, J. Gale and Y. Kaya (Eds.) © 2003 Elsevier Science Ltd. 

All rights reserved 

Individual Response: As described above, once an owner or operator has met all regulatory 

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

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

enforcement for regulatory noncompliance. 

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

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

discussion of EPA's final approach. 

Letter ID: 0142 Comment ID: 22576 Letter Lines: 1310 to 1329 

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

Comment: Preamble Questions: Injection of CO2 for the purposes of enhanced oil and gas 

recovery (EOR/EGR), as long as any production is occurring, will continue to be 

permitted under the Class II program. 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. EPA Notice 48. 

NGWA Response: The transition of carbon dioxide injection wells from Class II 

(Enhanced Oil Recovery wells) to Class VI (carbon sequestration wells) will 

presumably be requested when production of the petroleum has ceased. Liquid 

carbon dioxide from a distant source, such as a power plant, can be stored in 

the depleted petroleum reservoir even after production has ceased, necessitating 

a change in classification of the injection well. The new use of the wells 

involves much longer storage time, and raises concerns about mechanical 

integrity and long term effects, including geochemical changes, on underground 

source of drinking water (USDWs). The reclassification should depend on a 

positive outcome from a Class V experimental program conducted in the depleted 

reservoir. See NGWA Comment Document (word document) Section titled 

""Classification of Injection Wells for Carbon Sequestration, Class II Injection 

44
Well Transition, and Grandfathering"" for further details. 

Individual Response: EPA agrees 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). 

EPA adds that, following re-permitting as Class VI wells, these projects must be subject to the 

operational, MIT, monitoring, reporting, plugging, and post-injection site care and site closure 

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

preamble to the GS rule for additional detail on these requirements. 

Letter ID: 0142 Comment ID: 22577 Letter Lines: 1331 to 1337 

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

Comment: Preamble Questions: EPA seeks comment on how the grandfathering approach for 

existing wells may affect compliance with the other requirements in its 

proposal. EPA Notice 50. 

NGWA Response: See NGW Comment Document (word document) Section titled 

"Classification of Injection Wells for Carbon Sequestration, Class II Injection 

Well Transition, and Grandfathering" for further details. 

Individual Response: EPA disagrees that every GS well should initially be permitted as a Class 

V well, as suggested by the commenter in the document on classification of injection wells for 

geologic sequestration. The Agency believes that the tailored Class VI requirements including 

extensive requirements for geologic site characterization at §146.82, AoR evaluation at §146.84, 

and testing of the well during drilling at §146.87 are appropriate to ensure that permitting 

authorities have the necessary information to evaluate whether a specific site will allow safe 

injection of CO2. EPA adds that submittal and review of monitoring data (as required at 

§146.90) and the AoR reevaluation process (§146.84(e)) will provide an opportunity for an 

ongoing review of the site and a dialogue between the Director and the owner or operator to 

ensure that the project is being operated in a manner that protects USDWs from endangerment. 

Given this approach to permitting Class VI projects, EPA believes that the requirements for 

grandfathering of construction at §146.81(c) are necessary and appropriate. 

Letter ID: 0142 Comment ID: 22578 Letter Lines: 1339 to 1346 

Comment Code: 4322 2.4.4.1.1 Comments in favor of requiring injection below the lowermost 

45
USDW 

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

USDWs in certain circumstances 

Comment: Preamble Questions: The location and proximity of other formations to USDWs may 

preclude their use for GS. EPA seeks comment on prohibiting injection into such 

formations if they are above the lowermost USDW. EPA Notice 54. 

NGWA Response: NGWA supports the general prohibition against injections above 

the lowermost USDW. An exemption process should be available to review and 

consider those specific situations where injection cannot be done, or is being 

proposed not to be done, below the lowermost USDW 

Individual Response: EPA agrees that protecting USDWs from endangerment must be a top 

priority. The Agency believes 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 nonUSDW 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. It also establishes procedures for public notice of a waiver application and for DirectorRegional Administrator communication and requirements specifying information that owners or 

operators must submit, and Directors must consider, in consultation with PWSS Directors. 

Letter ID: 0142 Comment ID: 22579 Letter Lines: 1348 to 1366 

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

(seeking comment) 

Comment: Preamble Questions: EPA’s proposal would provide the Director the discretion to 

require the owner or operator to identify and characterize additional confining 

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

could further impede vertical fluid movement and allow for pressure dissipation. 

EPA says that these layers could provide additional sites for monitoring, 

mitigation, and remediation. EPA’s proposal would not require that these 

additional zones be identified for all GS sites because their absence does not 

necessarily indicate inappropriateness of a GS site. However, if such zones are 

present, information about their characteristics can provide inputs for 

predictive models, identify appropriate monitoring locations, and improve public 

confidence in and acceptance of a proposed GS site. EPA specifically seeks 

comment on the merits of requiring the identification of these additional zones. 

EPA Notice 64. 

46
NGWA Response: While NGWA believes that a site with a single confining can 

provide storage integrity, NGWA recommends that if there are additional 

confining layers at the site they should be characterized to get a better 

estimate of leakage risk to USDWs and possibly identify additional monitoring 

zones. 

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. Any additional confining zones would need to be included in the 

geologic site characterization process, which the owner or operator would submit and the 

Director would review in determining whether to grant a permit. EPA is developing guidance on 

site characterization for GS projects to assist owners or operators and Directors in evaluating 

permit requirements and applications under §146.82. The guidance provides recommendations 

regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as 

performing the necessary geochemical, geomechanical, and geophysical analyses of the injection 

and confining zone. EPA expects that this guidance will assist permit writers in making an 

objective decision about requiring additional confining layers. The guidance can be found on 

EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Letter ID: 0142 Comment ID: 22580 Letter Lines: 1368 to 1385 

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

Comment: Preamble Questions: In some cases, owners or operators may choose to use 

proprietary models (i.e., not available for free to the general public). EPA 

says it is aware that the use of proprietary codes may prevent full evaluation 

of model results (e.g., NRC, 2007). Several popular codes in the petroleumreservoir engineering discipline are proprietary and owners or operators of 

particular sites may prefer to use these codes as they have previous experience 

with them, and they have been used in peer-reviewed studies to model CO2 

sequestration. When using a proprietary model, owners or operators should 

clearly disclose the code assumptions, relevant equations, and scientific basis. 

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

Notice 68. 

NGWA Response: Yes, use of commercial proprietary codes should be authorized. 

Proprietary doesn't mean secret. A proprietary code largely vetted by the 

industry can be the best application in many circumstances. To promote peer 

review and benchmarking, the assumptions and theories for all numerical models 

should be publicly available and the solution of any analytic equations used in 

the predictive process should be fully elaborated. 

Individual Response: As described above, EPA agrees that available proprietary models may 

meet the complex needs for calculating the AoRs of GS sites, and shares their concern about the 

47
need to evaluate the inputs and assumptions used. EPA will allow the use of proprietary models 

in meeting the requirements for the GS regulation, as long as GS well operators using a 

proprietary model clearly disclose, to the Director's satisfaction, the code assumptions, relevant 

equations, and scientific basis. EPA adds that its Confidential Business Information requirements 

at 40 CFR 144.5 will apply to the use of proprietary models. 

Letter ID: 0142 Comment ID: 22581 Letter Lines: 1387 to 1392 

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

comment) 

Comment: Preamble Questions: EPA seeks comment on the applicability of computational 

fluid flow models for delineating the AoR of GS sites. EPA Notice 69. 

NGWA Response: See NGWA General Comment Document Section titled "General 

Comments on Use of Modeling for Ground-Water Protection Related to CO2 

Sequestration". 

Individual Response: As described above, EPA agrees that complex modeling techniques may 

be required to calculate the AoR while adequately accounting for the complexities of a GS site 

and all phases of a CO2 plume. 

Letter ID: 0142 Comment ID: 22582 Letter Lines: 1394 to 1400 

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

Comment: Preamble Questions: 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. EPA Notice 72. 

NGWA Response: Yes, reevaluation is needed and at a higher frequency than 10 

years, particularly at the beginning. 

Individual Response: EPA agrees 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 

48
has reason to believe, based on site-specific information, that a five-year reevaluation schedule is 

not sufficiently protective of USDWs. 

Letter ID: 0142 Comment ID: 22583 Letter Lines: 1402 to 1413 

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

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

Comment: Preamble Questions: EPA proposes to allow a phased approach to corrective action 

but says this may not be appropriate in all situations; therefore EPA is 

proposing that the Director have the discretion to decide to allow this 

approach, based on the understanding of relevant geologic and site conditions. 

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. EPA Notice 

74. 

NGWA Response: Yes, phased corrective action is a good idea. It will allow 

targeting of those wells most in need of corrective action and optimize 

financial resources as the pressure/CO2 plume may deviate from the initial AoR. 

That's why it is important to review AoR more often than 10 years. 

Individual Response: EPA acknowledges the commenter’s support of phased corrective action 

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

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

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

movement of the CO2 plume or pressure front. EPA believes that the phased corrective action 

approach is appropriate for GS projects, and retained it at §146.84(b)(2)(iv) in the final GS 

regulation. 

Also, as described above, EPA changed the minimum frequency for the AoR reevaluation at 

§146.84(e) from 10 years to 5 years in the final GS rule. 

Letter ID: 0142 Comment ID: 22585 Letter Lines: 1415 to 1438 

Comment Code: 4322 2.4.4.1.1 Comments in favor of requiring injection below the lowermost 

USDW 

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

USDWs in certain circumstances 

Comment: Preamble Questions: 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. EPA Notice 93. 

49
NGWA Response: NGWA supports the general prohibition against injections above 

the lowermost USDW. An exemption process should be available to review and 

consider those specific situations where injection cannot be done, or is being 

proposed not to be done, below the lowermost USDW 

Proposed Rule: 144.6(f) 

Comment: NGWA supports the general prohibition against injections above the 

lowermost USDW. An exemption process should be made available to review and 

consider those specific situations where injection cannot be done, or is being 

proposed not to be done, below the lowermost USDW. 

Rationale: NGWA understands that there may be portions of the country that will 

not have adequate storage zones below the lowermost USDW. In these areas, the 

Association believes that storage above the lowermost USDW may be allowed on a 

site specific basis based on director discretion assuming that all other 

conditions are met. 

Individual Response: As described above, 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 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. 

Letter ID: 0142 Comment ID: 22586 Letter Lines: 1440 to 1445 

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

comment) 

Comment: Proposed Rule: 144.36(a) 

Comment: Would there be a scenario where a facility would stop and restart? 

Concern is to make sure temporarily stopped injection activity does not allow 

party to wait a period of time and then walk away or alternatively cause closure 

if only a temporary stop. 

Individual Response: EPA clarifies that the final regulation at 144.51(o) states that temporary 

or intermittent cessation of injection operations is not abandonment. Please see the requirements 

for approving plugging and abandonment plans pursuant to §§144.51(o)--(p), 146.10, and 

146.92. See also the discussion of plugging and abandonment in the preamble to the final rule. 

Letter ID: 0142 Comment ID: 22587 Letter Lines: 1449 to 1465 

50
Comment Code: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment Code: 3440 2.2.2.2 Evaluation of wells in the AoR (e.g., types of data to be 

reviewed) 

Comment: Proposed Rule: 144.55(a) 

Proposed Revision: (a) Coverage. Applicants for Class I, II, (other than 

existing), III or VI injection well permits shall identify the location of all 

known wells within the injection well's area of review which penetrate the 

injection zone, or in the case of Class II wells operating over the fracture 

pressure of the injection formation, all known wells within the area of review 

penetrating formations affected by the increase in pressure. Applicants for 

Class VI shall perform mapping with sufficient resolution as to make a 

comprehensive effort to identify wells that are not in the public record using 

aerial photography, aerial survey, or other methods acceptable to the director 

corrective action as specified in §146.84 if needed 

Rationale: Concern about the use of the term known wells. Public records 

search may not be adequate for older oil and gas wells, for example. Some 

language should be added so that A more proactive approach is used, e.g. 

physically walk site or do aerial review. 

Individual Response: The final rule leaves §144.55 unchanged from the existing UIC 

requirements; i.e., Class VI wells are not addressed in this provision. Based on its evaluation of 

all public comments and input on the proposed rule and NODA and Request for Comment, EPA 

has made many revisions to the GS Rule. See the final rule and preamble for further discussion 

on EPA's final approach. 

Letter ID: 0142 Comment ID: 22588 Letter Lines: 1467 to 1473 

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

Comment: Proposed Rule: 146.81(b) 

Revision or Comment: Comment: NGWA supports the use of Class VI as "specifically 

for geologic carbon sequestration and believes that EOR and GS should be 

sequential and not concurrent" 

No rationale provided 

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

oil and gas recovery should remain under the Class II Program. The Agency believes that the 

nature and risks of CO2 injection for the primary purpose of long term storage poses different 

risks than injection for the primary purpose of ER, and therefore has developed new Class VI 

regulations to address these unique risks. For example, the volume of CO2 anticipated to be 

injected for long term storage is significantly greater than for ER operations. Reservoir pressure 

51
conditions will also be different, with Class VI injection operations involving large volumes of 

CO2 and likely having higher pressures within their storage formations than Class II ER projects. 

Letter ID: 0142 Comment ID: 22589 Letter Lines: 1475 to 1496 

Comment Code: 1220 1.1.1.1 Terminology and definitions 

Comment: Proposed Rule: 146.81(d) [Definition - Area of review] 

Proposed Revision: Area of review means the region surrounding the geologic 

sequestration project that may be impacted by the injection activity. The area 

of review is based on computational modeling that accounts for the physical and 

chemical properties of all phases of the injected carbon dioxide stream and the 

zone of increased pressure created by the injection. 

Rationale: The AOR needs to be based on both the CO2 plume and the associated 

pressure front in order to completely identify the areas that may be affected by 

the injection 

Proposed Rule: 146.81(d) [Definition - Geologic sequestration project] 

Proposed Revision: Geologic sequestration project means an injection well or 

wells used to emplace a carbon dioxide stream. It includes the subsurface threedimensional extent of the carbon dioxide plume, associated pressure front, and 

displaced brine, as well as all USDWs and the surface area above that delineated 

region. 

Rationale: See Section 144.6(f). If an exemption is provided, USDWs below the 

CO2 plume or pressure front should be included in the AOR specifically. 

Individual Response: EPA agrees that the AoR definition should account for the impact of the 

CO2 plume on USDWs. 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 also modified the final definition of geologic sequestration project to read as 

follows: “Geologic sequestration project means an injection well or wells used to emplace a 

carbon dioxide stream beneath the 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.” 

52
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: 0142 Comment ID: 22590 Letter Lines: 1498 to 1653 ; 1667 to 1819 

Comment Code: 1240 1.1.1.3 Suggested changes/edits to rule language 

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

comment) 

Comment: Proposed Rule: 146.82 

Comment: NGWA raises the question of whether a requirement should be included 

that all applications for Class VI construction permits include a certification 

that the facility was designed by an appropriately qualified professional 

engineer with an option for an appropriate qualified professional geologist to 

certify the well design (taking into consideration confinement, injectivity, 

etc). 

Proposed addition: (1) Class VI - Test/Injection Well Construction and Testing 

Permit 

Proposed addition: (a) The Director shall deny a construction permit if 

construction of the well itself may endanger the health of persons or the 

environment 

Proposed addition: (b) For construction permit approval, reasonable assurance is 

required that the project will function in compliance with this chapter. The 

Director shall require an exploratory well for those projects located in an area 

where available information is lacking concerning geologic or hydraulic 

confinement or existing information indicates that geologic or hydraulic 

confinement may be poor or lacking. 

Proposed addition: (c ) For a Class VI well, issuance of a construction permit 

does not obligate the Director to authorize any operation of the well, unless 

reasonable assurance has been provided that the well can operate in compliance 

with this chapter. 

Proposed addition: (d) Information required in 40 CFR 144.31 (e)(1) through (6) 

Proposed addition: (e) A map showing the injection well(s) for which a permit is 

sought and the applicable area of review. Within the area of review, the map 

must show the number, or name and location of all injection wells, producing 

wells, abandoned wells, plugged wells or dry holes, deep stratigraphic 

boreholes, State or EPA approved subsurface cleanup sites, surface bodies of 

53
water, springs, mines (surface and subsurface), quarries, water wells and other 

pertinent surface features including structures intended for human occupancy and 

roads. The map should also show faults, if known or suspected. Only information 

of public record is required to be included on this map; 

Proposed addition: (f) The area of review based on modeling, using data obtained 

during logging and testing of the well and the formation as required by 

paragraphs (l), (r ), and (s) of this section; 

Proposed addition: (g) Information on the geologic structure and hydrogeologic 

properties of the proposed storage site and overlying formations, including 

Proposed addition: (1) Maps and cross sections of the area of review; 

roposed addition: (2) Location, orientation, and properties of known or 

suspected faults and fractures that may transect the confining zone(s) in the 

area of review and a determination that they would not interfere with 

containment; 

Proposed addition: (3) Information on seismic history including the presence and 

depth of seismic sources and a determination that the seismicity would not 

interfere with containment; 

Proposed addition: (4) Data on the depth, areal extent, thickness, mineralogy, 

porosity, permeability and capillary pressure of the injection and confining 

zone(s); including geology/facies changes based on field data which may include 

geologic cores, outcrop data, seismic surveys, well logs, and names and 

lithologic descriptions; 

Proposed addition: (5) Geomechanical information on fractures, stress, 

ductility, rock strength, and in situ fluid pressures within the confining zone; 

and 

Proposed addition: (6) Geologic and topographic maps and cross sections 

illustrating regional geology, hydrogeology, and the geologic structure of the 

local area 

Proposed addition: (h) All wells within the AOR and whose total depth is greater 

than the depth to the bottom of the lowermost USDW should be compiled. However, 

preventive corrective action should be undertaken only for those wells that 

penetrate the injection and confining zone(s) 

Rationale: A substantive risk analysis can be performed only if all the (known) 

wells within the AOR and between the injection formation and the bottom of the 

USDW are described. 

54
Proposed addition: (i) Maps and stratigraphic cross sections indicating the 

general vertical and lateral limits of all USDWs, water wells and springs within 

the area of review, their positions relative to the injection zone(s) and the 

direction of water movement, where known; 

Proposed addition: (j) Baseline geochemical data on subsurface formations, 

including all USDWs in the area of review; 

Proposed addition: (k) Proposed operating data: 

Proposed addition: (1) Average and maximum daily rate and volume of the carbon 

dioxide stream; 

Proposed addition: (2) Average and maximum injection pressure; 

Proposed addition: (3) The source of the carbon dioxide stream; and 

Proposed addition: (4) An analysis of the chemical and physical characteristics 

of the carbon dioxide stream; 

Proposed addition: (l) The compatibility of the carbon dioxide stream with 

fluids in the injection zone and minerals in both the injection and the 

confining zone(s), based on the results of the formation testing program, and 

with the materials used to construct the well; 

Proposed addition: (m) Proposed formation testing program to obtain an analysis 

of the chemical and physical characteristics of the injection zone and confining 

zone; 

Proposed addition: (n) Proposed stimulation program and a determination that 

stimulation will not interfere with containment; 

Proposed addition: (o) Proposed formation testing program to obtain an analysis 

of the chemical, physical and radiological characteristics of and other 

information on the injection zone. 

Proposed addition: (p) Proposed procedure to outline steps necessary to conduct 

injection operation; 

Proposed addition: (q) Engineering drawings of the surface and subsurface 

construction details of the system, including design features for surge control 

and water hammer protection; 

Proposed addition: (r ) Injection well construction procedures that meet the 

requirements of Section 146.86; 

55
Proposed addition: (s) Proposed area of review and corrective action plan that 

meets the requirements under Section 146.84; 

Proposed addition: (t) The status of corrective action on wells in the area of 

review; 

Proposed addition: (u) A demonstration, satisfactory to the Director, that the 

applicant has met the financial responsibility requirements under Section 

146.85; 

Proposed addition: (v) Proposed testing and monitoring plan required by Section 

146.90 

Proposed addition: (w) Proposed injection well plugging plan required by Section 

146.92(b) 

Proposed addition: (x) Proposed post-injection site care and site closure plan 

required by Section 146.93(a) 

Proposed addition: (y) Proposed emergency and remedial response plan required by 

Section 146.94; and 

Proposed addition: (z) Any other information requested by the Director. 

Proposed addition: (2) Required Class VI operation permit information 

Proposed Rule: 146.82(a) & (b) 

Revision or Comment: Renumber 2(a) & (b) 

Proposed Rule: 146.82(d) - (h) 

Revision or Comment: Renumber 2(d) - 2(h) 

Proposed Rule: 146.82(h) 

Proposed addition: (5) Contingency plans to cope with all shut-ins or well 

failures, including emergency discharge provisions; 

No rationale provided 

Proposed Rule: 146.82(i) 

Revision or Comment: Renumber 2(i) 

Proposed Rule: 146.82(j) 

56
Proposed revision: 2(j) Results of the formation testing program to obtain an 

analysis of the chemical, physical and radiological characteristics of and other 

information on the injection zone. 

No rationale provided 

Proposed Rule: 146.82(k) - (m) 

Revision or Comment: Renumber 2(k) - 2(m) 

No rationale provided 

Proposed Rule: 146.82(n) 

Proposed revision: 2 (n) Engineering drawings of the surface and subsurface 

construction details of the system, including design features for surge control 

and water hammer protection, including the following: 

Proposed addition: (1) Record drawings, based upon inspections by the engineer 

of record or persons under his direct supervision, with all deviations noted; 

Proposed addition: (2) Copies of the mill certificates of all casings used in 

the construction of the well; 

Proposed addition: (3) Certification of completion submitted by the engineer of 

record; 

Proposed addition: (4) An operation manual including emergency procedures; 

Proposed addition: (5) Proposed monitoring program and data to be submitted; 

Proposed addition: (6) Proof that the existence of the well and any associated 

monitoring wells have been recorded with the permanent warranty deed or other 

instrument of conveyance as a two page proviso or addendum that contains 

certification of the locations of the wells (by metes and bounds) and a detailed 

sketch of the parcel that shows the location of the well. The location shall be 

measured by a certified land surveyor, and shall contain the surveyor's 

signature, registration number, official seal, and the following statement: "I 

hereby certify that this survey was made under my responsible direction and 

supervision, and is a correct representation of the land surveyed." 

No rationale provided 

Proposed Rule: 146.82(o) - (y) 

57
Revision or Comment: Renumber 2(o) - (y) 

Proposed Rule: 146.82 

Proposed addition: (3) Operational Testing 

Proposed addition: (a) For Class VI wells, the construction permit includes a 

period of temporary injection operation for the purposes of long term testing. 

Prior to commencement of operational testing: 

Proposed addition: 1. Construction of the injection well shall be complete and 

the permittee shall submit a notice of completion of construction to the 

Director. 

Proposed addition: 2. Each well shall first be tested for integrity of 

construction, and shall be followed by a short term injection test of such 

duration to allow for the prediction of the operating pressure. 

Proposed addition: 3. The permittee shall submit the following information to 

the Director, as described in the permit. 

Proposed addition: a. A copy of the borehole television survey(s) 

Proposed addition: b. Geophysical logs, 

Proposed addition: c. Mechanical integrity test data, 

Proposed addition: d. Data obtained during the short term injection testing 

conducted according to subparagraph 2. above. 

Proposed addition: e. Confining zone data, 

Proposed addition: f. Background water quality data for the injection and 

monitor zones; 

Proposed addition: g. Waste stream analysis, 

Proposed addition: h. As-built well construction specifications, and 

Proposed addition: i. Other data obtained during well construction which 

demonstrates that the well will operate in compliance with this chapter. 

Proposed addition: 4. Any corrective action required under Section 146.84, shall 

be completed. 

Proposed addition: 5. Prior to granting approval for operational testing of a 

Class VI well, the Director shall consider the following information: 

Proposed addition: a. All available logging and testing program data on the 

well; 

Proposed addition: b. A demonstration of mechanical integrity 

Proposed addition: c. The anticipated maximum pressure and flow rate at which 

the permittee will operate; 

Proposed addition: d. The results of the formation testing program; 

58
Proposed addition: e. The actual injection procedure; 

Proposed addition: f. The compatibility of injected waste with fluids in the 

injection zone and minerals in both the injection zone and the confining zone; 

Proposed addition: g. The status of corrective action on defective wells in the 

area of review; and 

Proposed addition: (b) Written authorization for operational testing shall be 

obtained from the Director. Authorization shall be for up to two years or the 

expiration date of the construction permit, whichever is less, and is only 

renewable once as described in Section 146.91. The authorization shall specify 

the conditions under which operational testing is approved. The authorization 

shall include: 

Proposed addition: 1. Injection pressure limitation, 

Proposed addition: 2. Injection flow rate limitation, 

Proposed addition: 3. Injection well monitoring requirements, 

Proposed addition: 4. Effluent monitoring requirements, 

Proposed addition: 5. Weekly ground water sampling of monitor wells, 

Proposed addition: 6. Monthly specific injectivity testing, 

Proposed addition: 7. Reporting requirements, and 

Proposed addition: 8. An expiration date for the operational testing period not 

to exceed two years. 

Proposed addition: (c ) Before authorizing operational testing, the Director 

shall conduct an inspection of the facility to determine if the conditions of 

the permit have been met. 

Proposed addition: (d) A sampling frequency and reporting of less than once per 

month shall not be allowed. 

Proposed addition: (e) For Class VI wells, the duration of the operational 

testing period shall not exceed two years or the expiration date of the 

construction permit, whichever is less. If the Director has not issued an 

intent to issue an operation permit for the einjectionwell9s) by the end of the 

operational testing period, the permittee shall cease injection. 

Proposed addition: (f) For a Class VI well, if an operation permit has not been 

obtained for the well within two years after the cessation of operational 

testing, the permittee shall submit an application to the Director to plug and 

abandon the well in accordance with Section 146.92. 

Proposed addition: (4) The Director shall conduct periodic inspections during 

construction 

No rationale provided 

59
Individual Response: Based on its evaluation of all public comments and input on the proposed 

rule and NODA and Request for Comment EPA has made many revisions to the GS Rule. Please 

see the final rule and the discussion of geologic site characterization in the preamble for 

additional information. 

EPA clarifies that the final rule does not require an owner or operator to obtain a separate Class 

VI operational testing permit. However, EPA revised §146.82 so that the final regulation 

specifies separate requirements for information to be submitted with the permit application and 

before well construction is approved (at §146.82(a)) and information to be submitted before 

operation of the well is authorized (at §146.82(c)). Final information on injection zone pressures 

are required following drilling of the well, at §146.82(c)(4). 

EPA disagrees that the rule needs to specify the qualifications of owner or operator staff creating 

the permit submittals. EPA is developing a number of technical guidances and implementation 

materials to assist owners or operators and Directors in the permitting process. These guidances 

will provide suggestions on how to perform many of the activities necessary for applying for a 

permit, including developing all required plans and conducting site characterizations under 

§146.82. Technical guidances and implementation materials will be available on EPA's web site, 

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

Letter ID: 0142 Comment ID: 22591 Letter Lines: 1655 to 1665 

Comment Code: 1240 1.1.1.3 Suggested changes/edits to rule language 

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

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

comment) 

Comment: Proposed Rule: 146.82(c) 

Revision or Comment: Proposed Revision: 2(c ) Re-evaluation of Area of Review. 

After completion of the operational testing period, the Area of Review shall be 

re-evaluated, using a calibrated, multi-phase fluid flow model. The data 

collection during operational testing must be adequate for calibration of the 

model. If a calibrated model cannot be prepared using data collected during 

operational testing, the owner or operator shall apply for a new period of 

operational testing of up to two years in order to collect the required data. 

No rationale provided 

Individual Response: EPA agrees that AoR reevaluations should be based on the same type of 

modeling that is used to perform the initial delineation, but disagrees that the suggested change is 

necessary. EPA clarifies that all AoR modeling (including that which supports reevaluations) 

should be based on accepted, verified, and validated scientific methods. Under requirements at 

§146.84(b), the owner or operator must demonstrate in the proposed AoR and corrective action 

plan, to the satisfaction of the Director that the modeled AoR (and all updates) will be based on 

60
detailed geologic data collected on the site. EPA anticipates that any model that does this in a 

comprehensive and satisfactory manner would be approved by the Director. 

Letter ID: 0142 Comment ID: 22592 Letter Lines: 1821 to 1832 

Comment Code: 1240 1.1.1.3 Suggested changes/edits to rule language 

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

(seeking comment) 

Comment: Proposed Rule: 146.83(b) 

Proposed revision: (b) Owners or operators of Class VI wells must identify and 

characterize additional zones, if they exist, that will impede vertical fluid 

movement, allow for pressure dissipation, and provide additional opportunities 

for monitoring, mitigation and remediation. Vertical faults and fractures that 

transect these zones must be identified. 

Rationale: While NGWA believes that a site with a single confining can provide 

storage integrity we feel that if there are additional confining layers at the 

site they should be characterized to get a better estimate of leakage risk to 

USDWs and possibly identify additional monitoring zones. 

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. Any additional confining zones would need to be included in the 

geologic site characterization process, which the owner or operator would submit and the 

Director would review in determining whether to grant a permit. EPA is developing guidance on 

site characterization for GS projects to assist owners or operators and Directors in evaluating 

permit requirements and applications under §146.82. The guidance provides recommendations 

regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as 

performing the necessary geochemical, geomechanical, and geophysical analyses of the injection 

and confining zone. EPA expects that this guidance will assist permit writers in making an 

objective decision about requiring additional confining layers. The guidance can be found on 

EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Letter ID: 0142 Comment ID: 22593 Letter Lines: 1834 to 1844 

Comment Code: 1240 1.1.1.3 Suggested changes/edits to rule language 

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

Comment: Proposed Rule: 146.84(b)(2)(i) 

Proposed revision: (i) The owner or operator will reevaluate the AOR after two 

61
yearsof operational testing (prior to issuance of the operating permit), and 

after 5 years and then no less frequently than every 5 years for the life of the 

project; 

Rationale: NGWA believes that a frequency of every 10 years is too long to 

identify early discrepancies between the site performance and the site model. 

Seeing early difference will allow for earlier model updating and provide 

additional reduction in leakage risk. 

Individual Response: As described above, EPA agrees that reevaluations of the AoR every ten 

years may not be sufficient to ensure protection of USDWs from endangerment, and 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. 

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: 0142 Comment ID: 22594 Letter Lines: 1846 to 1856 

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

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

Comment: Proposed Rule: 146.84(c) 

Comment: There should be somewhere in the rules a requirement that "mutual 

interference effects" should trigger reevaluation and re-delineation of the AORs 

of all projects that are interferring with each other. In essence, when a new 

project is submitted for permitting, there should be a system-wide, "regional" 

entity charged with ensuring that AORs for each project are appropriate, and 

perhaps that a "hybrid" or "combo AOR" be defined for the set of mutuallyinterferring projects. 

No rationale provided 

Individual Response: EPA anticipates that the impacts of multiple operators injecting into 

hydraulically connected formations will be accounted for in the initial AoR calculation. EPA 

adds that the owner or operator must demonstrate, in the proposed AoR and corrective action 

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

data collected on the site and includes consideration of existing conditions such as the presence 

of multiple operators. EPA adds that if any new GS projects are permitted within the AoR of a 

GS project between AoR evaluations, the AoR reevaluation would need to address such projects. 

EPA also expects that the permitting of the newer GS project would have considered the 

presence of an existing GS project. 

62
EPA understands that the CO2 plumes for large GS projects may cross State, Tribal, Territorial, 

EPA Regional, or national boundaries. The final GS rule, at §146.82(a)(2), requires the owner or 

operator to identify all State, Tribal, and Territorial boundaries within the AoR. Based on this 

information, the Director must provide written notification to all States, Tribes, and Territories to 

inform them of the permit application, as specified in §146.82(b) and ensure that they are 

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

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

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

information sharing and encourage safe, protective projects. 

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

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

among States, Tribes, and Territories interested in obtaining primacy during the implementation 

phase of the GS regulation. Such communication may involve other organizations such as the 

Sierra Club, NDWAC, associations, and other experts. However, the responsibility for 

addressing such subjects ultimately rests with the States, Tribes, and Territories with primacy. In 

addition, EPA is developing guidances for states that describe the process of applying for and 

receiving primary enforcement responsibility (primacy) for GS Class VI wells under Section 

1422 of SDWA, as well as the technical and administrative issues on developing GS regulations 

that are the equivalent of minimum Federal criteria and requirements. The guidance will be 

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

Letter ID: 0142 Comment ID: 22595 Letter Lines: 1858 to 1868 

Comment Code: 1240 1.1.1.3 Suggested changes/edits to rule language 

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

Comment: Proposed Rule: 146.84(c)(1)(i) 

Proposed revision: (i) Be based on detailed geologic data collected to 

characterize the injection zone, confining zone(s), transmissive monitoring 

zones and any additional zones; and anticipated operating data, including 

injection pressures, rates and total volumes over the proposed life of the 

geological sequestration project; 

Rationale: NGWA proposes that if there are secondary confining units that they 

should be included in the site model along with any transmissive zones between 

the primary and secondary confining units. 

Individual Response: EPA agrees that additional confining and containment zones should be 

accounted for in the AoR delineation if site-specific circumstances indicate a need for this. 

146.84 (c)(1)(i) specifies that computational modeling should be based on detailed geologic data 

collected to characterize the injection zone and confining zone, as well as any additional zones. 

63
Letter ID: 0142 Comment ID: 22596 Letter Lines: 1870 to 1880 

Comment Code: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment Code: 3440 2.2.2.2 Evaluation of wells in the AoR (e.g., types of data to be 

reviewed) 

Comment: Proposed Rule: 146.84(c)(2) 

Proposed revision: (2) Using methods approved by the Director, identify all 

penetrations, including active and abandoned wells and underground mines, in the 

area whose total depth is greater than the depth to the bottom of the lowermost 

USDW, including those penetrating the confining zone. Provide a description of 

each well’s type, construction, date drilled, location, depth, record of 

plugging and/or completion, and any additional information the Director may 

require; and 

Rationale: This makes this consistent with NGWA's proposed section 146(a)(8) 

Individual Response: EPA clarifies that any well that penetrates the confining zone, even if it 

does not extend all the way through the confining formation, is to be included in the tabulation. 

EPA is issuing guidance on. The guidance describes EPA's recommended approaches for the 

data to be considered in an initial AoR delineation, how to apply computational modeling to 

delineate the AoR, how to identify all wells that require corrective action, performing corrective 

action at GS sites, and, when appropriate, completing AoR reevaluations. The guidance will be 

available on EPA's web site, at 

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

The final rule retains the language in §146.84(c)(2) as proposed. EPA clarifies that the mapping 

and cross sections required to be submitted under §146.82(a)(3) will define the limits of the 

confining zone, which would be accounted for in the AoR delineation and corrective action 

evaluation required at §146.84(c). EPA adds that owners or operators must also, under 

§146.82(a)(2), submit a map of the AoR that shows all injection wells, producing wells, 

abandoned wells, plugged wells or dry holes, deep stratigraphic boreholes, State or EPA 

approved subsurface cleanup sites, surface bodies of water, springs, mines (surface and 

subsurface), quarries, water wells and other pertinent surface features including structures 

intended for human occupancy and roads. EPA believes that these requirements address the 

commenter's concerns. 

Letter ID: 0142 Comment ID: 22597 Letter Lines: 1882 to 1891 

Comment Code: 1240 1.1.1.3 Suggested changes/edits to rule language 

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

Comment: Proposed Rule: 146.84(f) 

Proposed revision: (f) At the minimum fixed frequency, not to exceed two years 

64
if under operational testing (prior to issuance of the operating permit), or 5 

years (if operating permit has been issued), as specified in the area of review 

and corrective action plan or when monitoring and operational conditions 

warrant, owners or operators must: 

Rationale: This makes this consistent with NGWA's proposed revision to Section 

146.84(b)(2)(i) 

Individual Response: EPA agrees 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: 0142 Comment ID: 22598 Letter Lines: 1893 to 1898 

Comment Code: 5430 2.9.1 Comments on proposed financial responsibility requirements (40 

CFR 146.85) 

Comment: Proposed Rule: 146.85(a) 

Comment: A question was raised during discussions about how the producer of the 

CO2 is impacted and whether they should maintain some liability. 

No rationale provided 

Individual Response: Once an owner or operator has met all regulatory requirements under Part 

146 for Class VI wells and the Director has approved site closure pursuant to requirements at 

§146.93, the owner or operator will generally no longer be subject to enforcement for regulatory 

noncompliance. Furthermore, their financial instrument as required under §146.85 will be 

released if it was not used. However, even if a site closure is approved under §146.93, an owner 

or operator may be held liable for regulatory noncompliance (including violation of 40 CFR 

144.12) in certain circumstances. For example, an owner or operator may be held liable for 

regulatory noncompliance even after site closure was approved if the Director relied on 

erroneous information (e.g., erroneous modeling data) provided by the owner or operator when 

approving site closure. 

Additionally, an owner or operator may always be subject to any action the Administrator deems 

necessary to protect the health of persons under §1431 of the SDWA after site closure if there is 

unanticipated migration towards or into a USDW that causes or threatens imminent and 

substantial endangerment to public health. The action may include issuing administrative orders 

65
or commencing a civil action for appropriate relief. If the owner or operator fails to comply with 

the order, they may be subject to a civil penalty for each day in which such violation occurs or 

failure to comply continues. 

The Agency clarifies that Class VI well permits may be transferred to another owner or operator 

pursuant to §144.38 whereby generally all other regulatory responsibilities are transferred to that 

new owner and operator, which includes all potential liabilities associated with meeting the 

requirements of that permit. Please see further clarification on the issue of long term liability in 

the preamble of the final rule. 

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

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

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

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

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

EPA's final approach. 

Letter ID: 0142 Comment ID: 22599 Letter Lines: 1900 to 1909 

Comment Code: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment Code: 5430 2.9.1 Comments on proposed financial responsibility requirements (40 

CFR 146.85) 

Comment: Proposed Rule: 146.85(b) 

Proposed revision: (b) The owner or operator must provide to the Director, at 

the same frequency as the AOR reevaluation, written updates of adjustments to 

the cost estimate to account for any amendments to the area of review and 

corrective action plan (§146.84), the injection well plugging plan (§146.92), 

and the post-injection site care and site closure plan (§146.93). 

Rationale: NGWA proposes that potential changes in the size of the AOR require 

that all site plans be reevaluated at the same frequency as the AOR. 

Individual Response: EPA agrees that it is important to periodically update cost estimates that 

support financial responsibility determinations. EPA clarifies that the GS rule, at §146.85(c) 

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. See the final rule and 

preamble for further discussion of EPA's final approach to financial responsibility. 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). The owner or operator must also update the cost estimate annually to 

adjust for inflation under §146.85(c)(2). 

66
Letter ID: 0142 Comment ID: 22600 Letter Lines: 1911 to 1913 

Comment Code: 3820 2.3.1 Well construction procedures 

Comment: Proposed Rule: 146.86(a)(3) 

Comment: NGWA supports this provision 

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

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

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

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

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

Letter ID: 0142 Comment ID: 22601 Letter Lines: 1915 to 1917 

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

comment) 

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

Comment: Proposed Rule: 146.86(b)(1) 

Comment: NGWA supports this provision 

Individual Response: EPA agrees that cement that is compatible with the CO2 and formation 

fluids will enhance Class VI well integrity. EPA also agrees that developing technology in the 

field of acid-resistant cement will provide the industry with future benefits. In the interest of 

USDW protection, the Agency requires that the materials used in Class VI wells be compatible 

with fluids with which they may come in contact, as specified in §146.86(b)(1). 

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

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

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

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

See the discussion of Class VI well construction requirements in the preamble to the final GS 

rule for additional information. Additionally, EPA is developing guidance on the construction of 

Class VI wells. This guidance will be available on EPA’s website at 

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

Letter ID: 0142 Comment ID: 22602 Letter Lines: 1919 to 1921 

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

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

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Comment: Proposed Rule: 146.86(b)(3) 

Comment: NGWA supports this provision 

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: 0142 Comment ID: 22603 Letter Lines: 1923 to 1926 

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

Comment: Proposed Rule: 146.86(b)(5) 

Comment: NGWA supports this provision and especially that the assessment should 

include the radial integrity of the cement. 

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

with the CO2 and formation fluids will enhance Class VI well integrity. The final rule retains 

this provision. 

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 

68
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: 0142 Comment ID: 22604 Letter Lines: 1928 to 1935 

Comment Code: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment Code: 3866 2.3.3.3 Logging and testing requirements (40 CFR 146.87) 

Comment: Proposed Rule: 146.87(a)(3)(ii) 

Proposed revision: (ii) A cement bond, variable density log, and radial cement 

evaluation log and a temperature log after the casing is set and cemented. 

Rationale: NGWA supports inclusion of a radial cement evaluation log in 

addition. The addition of this test will help identify any potential channels 

in the cement out from casing 

Individual Response: EPA clarifies at §146.87(a)(2)(ii) that owners or operators must perform a 

cement bond (i.e., cement evaluation) log after the casing is set and cemented. 

Letter ID: 0142 Comment ID: 22605 Letter Lines: 1937 to 1939 

Comment Code: 3866 2.3.3.3 Logging and testing requirements (40 CFR 146.87) 

Comment: Proposed Rule: 146.87(a)(4) 

Comment: NGWA supports the inclusion of this series of tests. 

Individual Response: EPA acknowledges the comment and agrees that logging and testing 

requirements are appropriate and necessary. The requirements at §146.87 stem from existing 

knowledge and practices in place for other injection well classes and within the oil and gas 

industry, and are tailored to the special characteristics of CO2 injection for GS. The final rule 

retains the requirements for demonstration of internal and external mechanical integrity required 

at §146.87(a)(4). 

Letter ID: 0142 Comment ID: 22606 Letter Lines: 1941 to 1949 

Comment Code: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment Code: 4543 2.5.2.1 MIT procedures and methods for GS (seeking comment) 

Comment: Proposed Rule: 146.89(c) 

Proposed revision: At least once per year, the owner or operator must use one 

of the following methods, as approved by the director, to determine the absence 

69
of significant fluid movement under paragraph (a)(2) of this section. 

Rationale: There was a question as to whether one of these tests individually 

would suffice in all circumstances. The change proposed is to allow the 

director to review the proposal. 

Individual Response: EPA clarifies that all MITs the owner or operator proposes to use must be 

described in the proposed testing and monitoring plan, which must be approved by the Director. 

See §146.90. EPA believes that the MITs described in §146.89(c) of the rule (e.g., an approved 

tracer log or temperature or noise logs) are effective methods to demonstrate external MI, 

provide an important early warning of potential problems in the injection well system, and 

represent standard techniques that have been used successfully by the drilling industry and for 

the UIC Program for decades. The Agency notes that the regulations do provide the Director 

flexibility at §146.89(e) to approve the use of alternative MIT methods. 

Letter ID: 0142 Comment ID: 22607 Letter Lines: 1951 to 1954 

Comment Code: 4660 2.6.6 Geochemical monitoring 

Comment: Proposed Rule: 146.90(d) 

Comment: The monitoring should be site specific and include particular analytes 

at risk to the aquifer from the existing geologic environment. 

Individual Response: While each monitoring plan must be site-specific based on data collected 

during the initial site characterization and baseline geochemical monitoring, it is likely that 

geochemical sampling might include basic water quality parameters such as pH, specific 

conductivity, temperature, CO2, alkalinity, major ions, and select heavy metals. Additional 

parameters may be monitored based on the potential for leaching of minerals or the geochemistry 

of native fluids. 

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: 0142 Comment ID: 22608 Letter Lines: 1958 to 1964 

Comment Code: 4640 2.6.4 Pressure fall-off testing (seeking comment) 

Comment: Proposed Rule: 146.90(f) 

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Comment: What additional information does this test provide that is not 

available from other sources? The perception from some of our reviewers is that 

there may not be much information that is gathered that is not already available 

from other sources. If there is no significant additional information 

provided, running the test may not be necessary. 

Individual Response: EPA disagrees and 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. 

Letter ID: 0142 Comment ID: 22609 Letter Lines: 1968 to 1975 

Comment Code: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment Code: 4610 2.6.1 Testing and monitoring plan requirement (seeking comment) 

Comment: [In the text below, text in CAPS denotes added text.] 

Proposed Rule: 146.90(h)(1) 

Proposed revision: (1) The testing and monitoring plan must be based on 

potential RISKS within the area of review; 

Rationale: Risk is more generally accepted and understood. 

Individual Response: The final rule at §146.90(h)(1) incorporates the suggested revision. Based 

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

for Comment EPA has made many revisions to the GS rule. See the final rule and preamble for 

further discussion on EPA's final approach. 

Letter ID: 0142 Comment ID: 22610 Letter Lines: 1977 to 2177 

Comment Code: 1240 1.1.1.3 Suggested changes/edits to rule language 

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

comment) 

Comment: Proposed Rule: 146.91 

Proposed addition: (1) Class VI Test/Injection Well Construction Permit 

71
Proposed addition: (a) The Director shall require periodic data reports and 

progress reports during construction that include: 

Proposed addition: 1. Driller's log 

Proposed addition: 2. Geophysical surveys 

Proposed addition: 3. Core analyses 

Proposed addition: 4. Lithologic logs 

Proposed addition: 5. Drill stem tests 

Proposed addition: 6. Pump tests 

Proposed addition: 7. Daily job (construction) reports 

Proposed addition: 8. Water quality analyses 

Proposed addition: (b) The frequency of reporting shall be specified in the 

individual permit 

Proposed addition: (c ) Interpretation of data is required in the data reports 

or progress reports at the completion of each significant phase of construction, 

such as completion of test well construction and testing, completion of 

injection well construction, and completion of injection well testing. 

Proposed addition: (d) The owner or operator shall submit final reports of all 

data collected from the test injection ell with interpretations to the Director 

with the application for a Class VI Test/Injection Well Construction and Testing 

Permit and a Class VI Injection Well Operation Permit shall include all 

information and data collected under Section 146.87, with appropriate 

interpretations 

Proposed addition: (2) Class VI Operational Testing Permit 

Proposed addition: (a) The owner or operator shall submit, as part of the permit 

application, the proposed methodology for collection and reporting of 

operational data, to ensure that the data is collected, correlated, and reported 

in a fashion that would enable the Director to evaluate well performance. 

Proposed addition: (b) All Class VI wells shall report monthly the following: 

Proposed addition: 1. Operating reports to the Director on: 

Proposed addition: a. The physical, chemical, and other relevant 

characteristics of injection fluids; 

Proposed addition: b. Daily reading of the pressure and flow for each well. For 

each Class VI sequestration well, a specific injectivity test shall be performed 

quarterly; 

Proposed addition: c. Monthly average, maximum and minimum values for injection 

72
pressure, flow rate and volume, and annular pressure; and 

Proposed addition: d. The results of monitoring prescribed under Section 146.90 

Proposed addition: 2. Reporting the results, within three months after the 

completion of: 

Proposed addition: a. Annular monitoring tests of mechanical integrity; 

Proposed addition: b. Any other test of the injection ell conducted by the 

permittee if required by the Director; and 

Proposed addition: c. Any well work over. 

Proposed addition: (c ) Specific injectivity testing shall be performed while 

the pumping rate to the well(s) has been set at a predetermined level and 

reported as the specific injectivity index (gpm/specific pressure (psig)). As 

part of this test, the well shall be shut-in for a period of time necessary to 

conduct a valid observation of pressure fall-off. The owner or operator shall 

propose which pumping rate will be used based on the expected flow, the design 

of the pump station including the volume of the wet well and pump type(s), and 

the type of pump controls used. The pumping rate(s) shall be included as a 

condition of the operation permit. 

Proposed addition: (d) Re-evaluation of Area of Review. After completion of the 

operatonal testing period, the Area of Review shall be re-evaluated, using a 

calibrated, multi-phase fluid flow model. The data collection during 

operational testing must be adequate for calibration of the model. If a 

calibrated model cannot be prepared using data collected during operational 

testing, the owner or operator shall apply for a new period of operational 

testing of up to two years in order to collect the required data. No more than 

two operational testing permits can be issued for any Class VI well. If the 

recalculated Area of Review includes any relevant wells or penetrations through 

the confining zone that were not reported in the permit application, a new 

tabulation of penetrations as required in Section 146.84(c)(2) and (3) shall be 

provided. Owners or operators must perform corrective action as required in 

Section 146.84(d). 

Proposed addition: (e) If physical or geochemical data such as water quality, 

pressure changes, or mechanical integrity test results indicate that fluid 

movement into or between underground sources of drinking water may be occurring, 

the permittee shall submit additional data to provide reasonable assurance that 

the injection operation is in compliance with the requirements of this chapter. 

This additional data shall be submitted with the periodic operations reports, 

the content and frequency of which are specified in the individual permit. 

73
Proposed addition: (f) A Class VI well permit shall be written to require that 

if CFR Section 146.14(a) is applicable, progress reports shall be submitted no 

later than thirty days following each interim date and the final date of 

compliance. 

Proposed addition: (3) Class VI Injection Well Operation Permit. 

Proposed addition: (a) The applicant shall submit, as part of the permit 

application, the proposed methodology for collection and reporting of 

operational data, to ensure that the data is collected, correlated, and reported 

in a fashion that would enable the Director to evaluate well performance. 

Proposed addition: (b) All Class VI wells shall report monthly the following: 

Proposed addition: 1. Operating reports to the Director on: 

Proposed addition: a. The physical, chemical, and other relevant characteristics 

of injection fluids; 

Proposed addition: b. Daily readings of the pressure and flow for each well. 

For each Class VI well, a specific injectivity test shall be performed 

quarterly; 

Proposed addition: c. Monthly average, maximum and minimum values for injection 

pressure, flow rate and volume, and annular pressure; and 

Proposed addition: d. The results of monitoring prescribed under Section 146.90 

Proposed addition: 2. Reporting the results, within three months after the 

completion of: 

Proposed addition: a. Periodic tests of mechanical integrity; 

Proposed addition: b. Any other test of the injection well conducted by the 

permittee if required by the Director; and 

Proposed addition: c. Any well work over. 

Proposed addition: (c ) Specific injectivity testing shall be performed while 

the pumping rate to the well(s) has been set at a predetermined level and 

reported as the specific injectivity index (gpm/specific pressure (psig)). As 

part of this test, the well shall be shut-in for a period of time necessary to 

conduct a valid observation of pressure fall-off. The owner or operator shall 

propose which pumping rate will be used based on the expected flow, the design 

of the pump stations including the volume of the wet well and pump type(s), and 

the type of pump controls used. The pumping rate(s) shall be included as a 

74
condition of the operation permit. 

(d) Re-evaluation of Area of Review. Every five years, the Area of Review shall 

be re-evaluated, using a calibrated, multi-phase fluid flow model. The data 

collection during operation must be adequate for calibration of the model. If a 

calibrated model cannot be prepared using data collected during operation, the 

owner or operator shall, within 90 days, apply for a new operation permit with a 

revised monitoring and testing plan designed to collect the required data. The 

re-issued Class VI operation permit shall be valid for a period of no more than 

two years. After two years of operation under a re-issued operating permit, the 

applicant shall again re- evaluate the Area of Review using a calibrated, multiphase fluid flow model and re-apply for a five-year operating permit. If the 

recalculated Area of Review includes any relevant wells or penetrations whose 

total depth is greater than the depth to the bottom of the lowermost USDW that 

were not reported in the permit application, a new tabulation of penetrations as 

required in Section 146.84(c)(2) and (3) shall be provided. Owners or operators 

must perform corrective action as required in Section 146.84(d) must perform 

corrective action as required in Section 146.84(d). 

No rationale provided 

Proposed Rule: Introductory text to 146.91 and 146.91(a)(1)-(4) 

Revision or comment: Proposed for deletion 

Rationale: Covered in proposed Section 146.91(3) and subsections 

Proposed Rule: 146.91(a)(5) 

Revision or comment: Renumber 3(e) 

Proposed Rule: 146.91(a)(6) 

Revision or comment: Renumber 3(f); delete "and" 

Proposed addition: (g) If physical or geochemical data such as water quality, 

pressure changes, or mechanical integrity test results indicate that fluid 

movement into or between underground sources of drinking water may be occurring, 

the permittee shall submit additional data to provide reasonable assurance that 

the injection operation is in compliance with the requirements of this chapter. 

This additional data shall be submitted with the periodic operations reports, 

the content and frequency of which are specified in the individual permit. 

Proposed addition: (h) A Class VI well permit shall be written to require that 

if CFR Section 146.41(a) is applicable, progress reports shall be submitted no 

later than thirty days following each interim date and the final date of 

75
compliance. 

No rationale provided 

Proposed Rule: 146.91(a)(7); 146.91(b)(1)-(3) 

Proposed for deletion 

Rationale: Covered in proposed Section 146.91(3) and subsections 

Proposed Rule: 146.91(c) 

Renumber (4) 

Individual Response: Based on its evaluation of all public comments and input on the proposed 

rule and NODA and Request for Comment EPA has made many revisions to the GS Rule. See 

the final rule and preamble for further discussion on EPA's final approach. EPA is developing 

guidances on injection well construction and on monitoring and testing that will assist owners or 

operators and Directors in performing the pre-operational logging and testing required at 

§146.86. This guidance will be available on EPA’s website at 

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

As described above, EPA clarifies that the final rule does not require an owner or operator to 

obtain a separate Class VI operational testing permit. However, EPA revised §146.82 so that the 

final regulation specifies separate requirements for information to be submitted with the permit 

application and before well construction is approved (at §146.82(a)) and information to be 

submitted before operation of the well is authorized (at §146.82(c)). Final information on 

injection zone pressures are required following drilling of the well, at §146.82(c)(4). 

Letter ID: 0142 Comment ID: 22611 Letter Lines: 2179 to 2190 

Comment Code: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment Code: 4730 2.7.3 Reporting associated with closure and post-injection site care 

Comment: Proposed Rule: 146.92(b) 

Proposed revision: (b) Well Plugging Plan. The owner or operator of a Class VI 

well must prepare; maintain; including updating on the same schedule as the 

update to the Area of Review; and comply with a plan that is acceptable to the 

Director. The requirement to maintain and implement an approved plan is 

directly... 

Rationale: The Area of Review re-evaluation should trigger a review and updating 

of all the plans (MMV, financial, plugging, emergency response...) on the same 

interval that the AOR is updated. NGWA suggests EPA check all timelines and 

make them compatible. 

76
Individual Response: EPA agrees that the AoR reevaluations offer a good opportunity to 

promote a dialogue between the owner or operator and the permitting authority. Additionally, 

EPA recognizes that the AoR reevaluation has the potential to change or add important data to 

the other project plans and therefore the Agency agrees that the other Class VI plans must be 

updated when an AoR reevaluation takes place. 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 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. EPA is 

preparing guidance for owners or operators on developing and updating all of the required GS 

project plans. The guidance will be available on EPA's web site, at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. See the final rule and 

preamble for further discussion on EPA's final approach regarding the GS project plans. 

Letter ID: 0142 Comment ID: 22612 Letter Lines: 2192 to 2208 

Comment Code: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment Code: 4730 2.7.3 Reporting associated with closure and post-injection site care 

Comment Code: 5100 2.8.1 Injection well plugging activities (seeking comment) (40 CFR 

146.92) 

Comment: Proposed Rule: 146.92(d) 

Proposed revision: (d) Plugging Reports for Class VI Wells. Within 60 days 

after completion of plugging and abandonment of a well or well field the 

permittee shall submit to the Director a final report which includes: 

Proposed addition: (1) Certification of completion in accordance with approved 

plans and specifications by an appropriately qualified engineer of record or 

professional geologist. 

Note: It is important that the engineer and/or geologist have expertise and 

training in injection well drilling technology, reservoir characterization and 

injection well construction and operation. 

Proposed addition: (2) Evidence, such as a sealed copy or certification from the 

county clerk, that a surveyor's plot of the location of the abandoned well has 

been recorded in the county courthouse property records. 

Individual Response: EPA agrees that appropriately qualified personnel (e.g., engineers and 

geologists) should be involved in all aspects of the GS operation, including the well plugging 

process. When the owner or operator (and/or the person who performs the plugging operation) 

77
signs the plugging report and certifies it as accurate; they are attesting to the fact that all required 

activities were performed by qualified personnel. This is required under §146.92(d) and is a 

condition of the permit that is enforceable under §1423 of the SDWA. EPA clarifies that, in 

addition to requiring appropriate well plugging, the Director retains the option of witnessing any 

plugging activity or testing at the well. 

EPA clarifies that §146.93(g) requires the owner or operator, as part of the closure process, to 

record a notation on the deed stating that the property was used for GS. In addition, 

§146.93(f)(1) requires submission of a survey plat indicating the location of the well to the local 

zoning authority, as well as to the Director. 

Letter ID: 0142 Comment ID: 22613 Letter Lines: 2212 to 2222 

Comment Code: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment Code: 4730 2.7.3 Reporting associated with closure and post-injection site care 

Comment Code: 5220 2.8.2.1 Post-injection monitoring activities 

Comment: Proposed Rule: 146.93(a) 

Proposed revision: (a) The owner or operator of a Class VI well must prepare; 

maintain; including updating on the same schedule as the update to the Area of 

Review; and comply with a plan for post-injection site care and site closure 

that meets the requirements of paragraph (a)(2) of this section and is 

acceptable to the Director. 

Rationale: The Area of Review re-evaluation should trigger a review and updating 

of the well plugging plan, and the post injection site care and closure plan. 

NGWA suggests EPA check all timelines and make them compatible. 

Individual Response: EPA agrees with the commenter that, in some cases, the appropriate postinjection monitoring strategy may end up being different than initially projected at the time of 

permit application and there may be a need to amend the post-injection site care and site closure 

plan. EPA is requiring that upon the cessation of injection, the owner or operator submit an 

amended post-injection site care and site closure plan or demonstrate to the Director that no 

changes to the original post-injection site care and site closure plan are necessary, as specified in 

§146.93(a)(3). EPA is not requiring formal periodic review and updates to the PISC and site 

closure plan throughout the injection phase. EPA does not expect that changes to this plan would 

be implemented until injection operations cease. EPA envisions that owners or operators will 

take into account similar considerations that guide updates to other project plans, e.g., 

monitoring and operational data and results of AoR reevaluations. 

EPA has also added a new provision at §144.39(a)(5) requiring a modification, revocation, or 

reissuance of a Class VI permit whenever the Director determines that a change in the permit is 

necessary based on an amended AoR and corrective action plan, testing and monitoring plan, 

injection well plugging plan, post-injection site care and site closure plan, or emergency and 

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remedial response plan is necessary. This would invoke the public notification procedures of 40 

CFR Part 124 and the modification would be incorporated into the permit. EPA adds that, if any 

monitoring or other site data indicate a need for amending the post-injection site care plan, the 

owner or operator is expected to amend the plan accordingly. 

Letter ID: 0142 Comment ID: 22614 Letter Lines: 2224 to 2250 

Comment Code: 1240 1.1.1.3 Suggested changes/edits to rule language 

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

Comment: Proposed Rule: 146.93(b)(1) 

Proposed revision: (1) The owner or operator shall continue to conduct 

monitoring as specified in the Director-approved post-injection site care and 

site closure plan for at least 30 years following the cessation of injection. 

At the Director's discretion, the monitoring will continue until the geologic 

sequestration project no longer poses an endangerment to USDWs. 

Rationale: NGWA believes some number should be included. 30 years is a number 

used in other EPA programs. The next question was whether the burden should be 

placed on the director to justify the longer number or on the operator to prove 

the site is stabilizing. It is suggested that the director be allowed to 

approve both a shorter or longer timeframe. With the next subsection, the 

burden is placed on the owner or operator to prove a shorter timeframe is 

acceptable, while allowing in this subsection the director to require monitoring 

beyond 30 years. 

Proposed Rule: 146.93(b)(2) 

Proposed revision: (2) If the owner or operator can demonstrate to the 

satisfaction of the Director that the geologic sequestration project no longer 

poses an endangerment to USDWs, the Director may approve an amendment to the 

post-injection site care and site closure plan to reduce the frequency of 

monitoring or may authorize site closure before the end of the 30-year period. 

Rationale: Makes this subsection compatible with 30 year timeframe proposed by 

NGWA in 146.93(b)(1) 

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 

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research studies and evaluation of public comments. While numerous commenters suggested that 

EPA shorten the monitoring timeframe, none of the commenters provided sufficient data or other 

evidence to warrant a change in the proposed timeframe. While the 10- or 30-year timeframe 

suggested by some of these commenters may be within the timeframe suggested in some studies, 

EPA believes that the potential risks of endangering USDWs will likely not decline within these 

timeframes and available data, including data submitted by commenters, do not support a 

different default timeframe. 

However, EPA recognizes that there may be sites where the 50 year post injection site care 

timeframe may be either not appropriate or more burdensome than necessary based on sitespecific conditions. For this reason, the GS rule offers owners or operators flexibility regarding 

the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or 

lengthen the PISC timeframe during the post-injection period based on site-specific data, 

pursuant to requirements at §146.93(b); or (2) affording the Director discretion to allow a Class 

VI well owner or operator to demonstrate, during the permitting process based on substantial 

data, that an alternative PISC timeframe may be appropriate if it ensures non-endangerment of 

USDWs pursuant to requirements at §146.93(c). 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to 

adjust the timeframe for a limited number of GS projects during the permitting process where 

substantial data exists to demonstrate that an alternative timeframe would be protective of 

USDWs, or based on data collected during the PISC period, is appropriate to address the range of 

sites where GS is anticipated to occur, to accommodate site-specific circumstances and various 

geologic conditions, and addresses commenters’ concerns, while ensuring USDW protection. 

Both approaches will utilize site-specific data, and be based on pressure monitoring and USDW 

impacts, as the commenter suggests. 

Letter ID: 0142 Comment ID: 22615 Letter Lines: 2252 to 2262 

Comment Code: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment Code: 5800 2.13 Comments on emergency and remedial response (40 CFR 146.94) 

Comment: Proposed Rule: 146.94(a) 

Proposed revision: (a) As part of the permit application, the owner or operator 

must provide the Director with an emergency and remedial response plan that 

describes actions to be taken to address movement of the injection or formation 

fluids that may cause an endangerment to a USDW during construction, operation, 

closure and post-closure periods. The emergency and remedial response plan must 

be reviewed and updated, as necessary, on the same schedule as the update to the 

Area of Review. 

Rationale: Keep same update schedule as AOR 

Individual Response: In response to comments on the duration of the emergency and remedial 

response plan, EPA clarifies that the plan will apply over the life of the GS project through the 

post-injection site care period (§146.94(a)). EPA has added a requirement at §146.94(d) that 

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owners or operators must review their emergency and remedial response plan within one year of 

an AoR reevaluation required under §146.84 or following significant changes to the facility. 

Subsequently, owners or operators must submit an amended plan or demonstrate to the Director 

that no amendment to the plan is needed based on the AoR reevaluation or any significant 

changes made to the facility.