This comment letter response contains two parts:

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

Notes about the response letters:

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

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

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

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

• Each response letter includes: comment text; an EPA

‐ assigned comment code; and an

individual response. These are described and explained below.

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

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

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

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

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

appropriately addressed.

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

Comment ID. Additionally, one or more Comment Codes (i.e., unique topic area ID) was assigned to each discrete point raised by a commenter. This information was added to

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

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

construction requirements).

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

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

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

commenter was given a unique response.

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

Each letter response is a compilation of each comment and its individual response, compiled in the order of the original comment letter. As a result of this process, there is

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

and attention to each comment letter that was submitted.

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

Responses on each topic area are compiled and are also available in the rulemaking docket.Docket ID No. EPA-HQ-OW-2008-0390

The North Dakota Industrial Commission, Oil and Gas Division offers the following comments on issues specifically iden tified by EPA in the preamble on which the Agency is seeking comment:

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

the GS of CO2 and how these efforts mi ght be used to better inform a final Federal rulemaking. EPA Notice 43497.

The North Dakota Industrial Commission has drafted legislation concerning capture and storage of carbon dioxide to be acted upon during the upcoming legislative session in January 2009. This legislation was crafted us ing the IOGCC model. If the legislation is enacted, administrative rules will be promulgated. As with most regulatory programs, the states are best qu alified to take state-specific issues into account and to tailor the regulatory needs to fit their unique circumstances. To this end, partial primacy for Class VI wells is imperative.

2. Injection of CO2 for the purposes of enhanced oil and gas recovery (EOR/EGR), as long as any pro duction 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 43502. This approach makes the most sense since enhanced recovery operations have proven successful at increasi ng and maximizing oil and gas recovery while successfully sequestering carbon dioxide. As long as produc tion of oil and gas is occurring, it would be inefficient and confusing to change the rule s and processes under which these wells are regulated.

3. EPA seeks comment on the approach to grandfather construction requirements at the Direct or’s discretion for existin g Class I, Class II, and Class V wells seeking to convert to Class VI wells, and whether additional construction requirements would be necessary to pr event endangerment to USDWs from the

GS of CO2. EPA Notice 43502. If a well has been utilized for injection and is properly constructed under existing regulations, it is constructed to prevent the migration of the injectate into a USDW. The demonstrated well performance is indicative that well construction is protective of USDWs. A review to verify the existing c onstruction as protective is sufficient to grandfather the construction as protec tive as a Class VI injection well.

4. Additionally, EPA seeks comment on how the grandfathering approach for existing wells may affect co mpliance with the other requirements in its proposal.

EPA Notice 43502.

See 3 above.5. EPA is proposing to preclude the inj ection of CO2 for long-term storage into coal seams where they are above the lo wermost USDW. EPA requests comment on this proposed prohibition. EPA Notice 43503. This arbitrary exclusion would eliminate a va st number of potent ial sequestration zones. Enhanced recovery operations abov e the lowermost USDW have been taking place for a very long time. Unmineable coals in North Dako ta are found in high clay content glacial till which, if unfractured, serves as an exce llent confining zone. Based upon carbon dioxide’s affinity to adhere to coals, it is unwise to ar bitrarily eliminate a potentially large number of s equestration zones. Exclusion of these zones even in areas where other abundant supplies of freshwater are available may severely limit sequestration options. These situations are best handled locally where all of the pertinent regional geologic fa ctors can be considered.

6. The location and proximity of other formations to USDWs may preclude their use for GS. EPA seeks comment on prohibiti ng injection into such formations if they are above the lowermo st USDW. EPA Notice 43503. This arbitrary exclusion would eliminate a va st number of potent ial sequestration zones. Enhanced oil and gas recovery opera tions above the lowermost USDW have been taking place for a very long time. Exclusion of these zone s where other abundant supplies of freshwater are available may unnecessarily limit sequestration options. These situations are best handled locally where all the pertinent regional geologic factors can be considered. The buoyancy of carbon dioxide suggests this in an unnecessary restriction since it would move injectate away from the USDWs below the sequestration zone.

7. By defining “carbon dioxide str eam” to exclude hazardous wastes (146.81(d)), EPA’s rule, if finalized, assu res that it would apply only to CO2

streams that are not hazardous wastes as defined in 40 CFR Part 261. As a result, EPA’s proposed rule would preclude the in jection of hazardous wastes in Class VI injection wells. EPA seeks comment on this approach and other

considerations associated wi th the presence of “impurit ies” in the CO2 stream.

EPA Notice 43503. The presence of certain hazardous wast es should not preclude the overall carbon dioxide stream from injection into a sequestr ation zone. The process of removing the carbon dioxide and making it su itable for transportation and in jection should render it relatively pure. The presence of impurities can be dealt with at a specific source and the overall waste stream certified for inject ion. If the well construction and geologic setting is suitable to confine the carbon dioxi de stream and prevent its migration into a USDW, then certain impurities and/or haz ardous wastes should be allowed.

8. Class VI requirements and permits will need to be carefully structured to ensure that they do not “authorize” inappropriate hazardous releases. This would include clarifying if there are pot ential releases from the well which are outside the scope of the Class VI permit. EPA requests comment on particular

situations where this mi ght occur. EPA Notice 43504.Carbon dioxide should not be classified as a hazardous waste. Carbon dioxide is

not hazardous or toxic under normal conditi ons. CERCLA liability will not only impact owners and operators of carbon dioxide sequestration proj ects, but also pore space owners. Subjecting pore space owners to CE RCLA liability and joint and several liability under CERCLA will greatly ham per carbon dioxide sequestr ation projects. EPA should take the opportunity in this rulemaking to alleviate any CERCLA liability concerns.

9. EPA also requests comment on other considerations associated with the presence of impurities in the CO2 stream related to CERCLA. EPA Notice 43504. CERCLA should not apply to carbon diox ide sequestration. EPA needs to provide

assurances to facilitate carbon dioxide sequestration projects.

10. EPA’s proposal would provide the Di rector 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 a nd allow for pressure dissipation. EPA says that these layers coul d provide additional sites fo r monitoring, mitigation, and remediation. EPA’s pr oposal 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 comme nt on the merits of requiring the identification of these additional zones. EPA Notice 43506. Redundant confining zones should not be requi red. If the primar y confining zone is adequate, by definitio n it is sufficient. If one sequestr ation site identif ies one confining

zone and another identifies mult iples, it may lead to public confusion and lack of confidence in a site that only has one confinin g zone even though it is just as protective.

11. EPA believes that predicting the comp lex multi-phase buoya nt flow of the CO2, “co-injectates,” and compounds that may be mobilized due to injection requires the sophistication of computational models. EPA proposes that the owners or operators of GS wells be required to delineate the AoR for CO2 GS sites using computational fluid flow models designed for the specific site conditions and injection regime. EPA seeks comment on the us e of modeling for

AoR delineation. EPA Notice 43506. There is concern about the lack of information necessary to construct a valid model in areas where the sequestrat ion zone has not been extensivel y studied. This lack of information may make modeling di fficult or not very useful. Any modeling used should

be re-examined and recalibrated over time with additional data gathered. Modeling should not be solely relied upon where real dat a offers a different view. Seismic and offset well data can help delineate the AOR.

12 In some cases, owners or operators may choose to use proprietary models (i.e., not available for free to the general pub lic). 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 petr oleum-reservoir engineering discipline are proprietary and owners or operators of particular sites may prefer to use these codes as they have previous experi ence with them, and they have been used in peer-reviewed studies to mode l CO2 sequestration. When using a proprietary model, owners or operators should clearly disclose the code assumptions, relevant equations, and scie ntific basis. EPA seeks comment on allowing the use of proprietary mode ls for GS sites. EPA Notice 43507. The use of proprietary models is widely us ed and accepted in oi l and gas reservoir simulation. These models are a logical fi t to simulate carbon dioxide sequestration projects. These models are verified using a history-matc h. The regulatory agency responsible for monitoring carbon dioxide sequestration does not need access to the

code in order to conduct or evaluate a hi story-match. A regulatory agency could conduct reservoir modeling using its own modelin g software to compare. Elimination of these widely used and understood reservoir m odels would be unwise. The assumptions and equations used in the mo deling along with a valid hist ory match will provide the regulating authority the ability to assess the model’s accuracy.

13. EPA seeks comment on the applicability of computational fluid flow models for delineating the AoR of GS sites. EPA Notice 43507. The use of computational flow models is appropriate, however; modeling should

not be the sole criteria to determine the AOR if ac tual measured data exists.

14. EPA seeks comment on requiring th e 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 fi xed frequency for Ao R reevaluation. EPA

Notice 43507. It is appropriate to reevaluate the AOR on a periodic basis. The conditions and frequency under which the AOR is reeval uated should be based upon monitoring.

15. EPA proposes to allow a phased approach to corrective action but says this may not be appropriate in all situatio ns; 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 43508. A phased approach is appropriate. Corrective action for some aspects of the project may not be necessary at the outset and a phased approach would allow an operator to optimize capital expenditures to make a project more feasible. Wholesale

corrective action at the outset of a project may ultimately resu lt in corrective action in areas unaffected by the projec t. In addition, the procur ement of rigs and other equipment and the time necessary to conduct co rrective actions in areas that might not be affected for a significant period of time could unnecessarily de lay a sequestration project.16. EPA seeks comment on the proposed GS well requirements for depth of surface casing, the cementing of long-st ring casing, and construction with a packer set opposite a cemented in terval. EPA Notice 43509. Requiring setting surface casing below the lowermost USDW would preclude injection above the lowermost USDW, which as earlier stated, woul d eliminate a vast number of potential s equestration zones. Enhanced recovery operations above the lowermost USDW have been taking place for a very long time. Exclusion of these zones where other abundant supplies of freshw ater are available may unnecessarily limit sequestration options. These situations are best handled locally where the regional geologic factors can be considered. Setting the surface casing below the lowermost USDW may not be technically fe asible. Cementing of the l ong-string casing to surface may not be desirable in all situations; an annulus that can be monitored may be desirable. The long-string casing should be cemented to at least above the upper confining zone. Requiring the packer be set opposite a cemented interval is appropriate.

17. EPA also seeks comment on how the proposed grandfathering provisions for existing wells (construction requireme nts) may affect compliance with the above, proposed construction requirements. EPA Notice 43509. If a well has been utilized for injection and is properly constructed under existing regulations, it is constructed to prevent the migration of the injectate into a USDW. The demonstrated well performance is indicative that it is protective of USDWs. A review to verify the construction is sufficient to gra ndfather the construction as protective as a Class VI injection well. Additi onal realistic remedial actions short of new construction could be required to make the well more protective.

18. EPA seeks comment on the merits of horizontal well drilling techniques for GS wells and the applicability of well c onstruction requirements discussed in this proposal. EPA Notice 43509.

Horizontal wells should be allowed. The drilling of these wells has become

common in certain basins. Their use would maximize injection while minimizing the surface footprint and injection pressure. Well construction requirements should be

similar to vertical wells i.e., the vertical portion of the well should be cemented to above the upper confining zone.

19. EPA seeks comment regarding require ments for degradati on-resistant well construction materials, such as acid-r esistant cements and corrosion resistant casing. EPA Notice 43510. Based upon history in carbon dioxide inje ction projects, construction requirements should be based upon actual n eeds as identified in these projects and upon actual subsurface conditions. Industry experience with carbon dioxide EOR projects supports the use of conventional tubing, casing, and cements. These wells have been demonstrated to protect USDWs. Corrosion mi tigation measures such as lined tubing, use of corrosion inhibitors, and proper dehydr ation of carbon diox ide provide adequate protection.20. EPA is requesting comment on the extent and scope to which hydraulic fracturing should be allowed during GS injection and whether the use of fracturing for the purposes of well stimul ation is appropriate. EPA Notice 43511. Hydraulic fracturing shoul d be allowed as long as it does not compromise the confining zone. Computer mode ling to predict the fracture growth can be utilized in fracture stimulation design.

21. EPA is also requesting information to better qualify the use of fracturing for GS injection in specific geologic se ttings and rock formation lithologies. EPA

Notice 43511. This type of information needs to be obtai ned from industry. Many basins have implemented hydraulic fracturing of certain formations for a number of years. These

situations are best handled lo cally where the regional g eologic factors can be

considered.

22. EPA seeks comment on the merits of requiring down-hole shut-off valves in

GS wells. EPA Notice 43511. Requiring down-hole shut-o ff valves may be problematic. To protect the entire tubing-casing annulus they would need to be installed at or bel ow the injection packer. This may make the tool prone to failure. These valves may restrict or preclude the running of down hole monitoring or logging tools. Inclusion of a seating nipple directly above the injection packer which would allow the inst allation of a wire line set plug may be more appropriate.

23. EPA is aware that the proposed re quirement of injecting CO2 below the lowermost USDW may prec lude injection into certain targeted geologic formations, which may be st orage sites currently under consideration for GS. As a result, the Agency is considering and requesting comme nt on alternative approaches that would allow injecti on between and/or above the lowermost USDW, and thus potentially allow for more areas to be available for GS while preventing USDW endangerment. EPA Notice 43512. Injection into a formation above the lowe rmost USDW should be allowed. As commented earlier, if injection above the lo wermost USDW is no t allowed it would

eliminate a vast nu mber of potential s equestration zones. Enhanced recovery operations above the lowermost USDW have been taking place for a very long time.

Exclusion of these zones where other abundant supplies of freshwater are available may severely limit sequestration options. These situations are best handled locally where other regional geologic factors can be considered. De monstration that the upper and lower confining zones are adequate to prevent migration should be sufficient. The

fact that the carbon di oxide plume is buoyant will protect any deeper USDW.

24. EPA is soliciting comment on whether CO2 injection should be allowed into an injection zone above the lowermost US DW, when the Director determines that geologic conditions (e.g., thousands of feet of intervening formations between the injection zone and the overlying an d/or underlying USDWs) exist that will prevent fluid movement into adjacent USDWs. EPA Notice 43512.Injection into a formation above the lowe rmost USDW should be allowed. As commented earlier, if injection above the lo wermost USDW is not allowed it would

eliminate a vast nu mber of potential s equestration zones. Enhanced recovery operations above the lowermost USDW have been taking place for a very long time.

Exclusion of these zones where other abundant supplies of freshwater are available may severely limit sequestration options. These situations are best handled locally where other regional geologic factors can be considered. De monstration that the upper and lower confining zones are adequate to prevent migration should be sufficient. The

fact that the carbon di oxide plume is buoyant will protect any deeper USDW.

25. EPA is also requesting comments on whether aquifer exemptions should be allowed for the purpose of Class VI inj ection, and under what conditions should such aquifer exemptions be approved. EPA Notice 43512. Aquifer exemptions should be allowed pu rsuant to existing requirements in other injection well classes.

26. EPA seeks comment on whether the Ag ency should set a minimum injection depth requirement for CO2 GS, rather than require that such injection take place

below the lowermost USDW. EPA Notice 43512. There should not be a minimum injection depth. The determining factor should be whether the project will be protective of USDWs. A minimum depth requirement suggests a requirement to inject carbon dioxi de in a supercritical ph ase. This is not appropriate since there may be projects w here injection of car bon dioxide in other phases is the most effective option.

27. EPA’s proposal allows Directors’ di scretion on whether to require the use of tracers, and if so, what types of tr acers. EPA seeks comment on the use of tracers in CO2 GS operations and any potential impact of tracers on human health or ecosystems as they relate to USDWs. EPA Notice 43513.

Discretion on whether to us e a tracer is appropriate. Radioactive tracers have been successfully utilized in oil and gas ope rations. The small amount used should not

threaten human health or USDWs. Howeve r, modeling and monitoring are generally more appropriate techniques to track a plume since tracers have a limited radius of investigation.

28. EPA’s proposal would require owners or operators of Class VI GS projects to monitor internal mechanical integrity of their injection wells by continuously monitoring injection pressure, flow rate , and injected volumes, as well as the annular pressure and fluid volume to as sure that no anomalies occur that may indicate an internal leak. EPA request s comment on the practicability of this requirement. EPA Notice 43513. The monitoring of this dat a is appropriate. Continu ous monitoring should be clarified as daily for most applications. Th is could be more stringent or frequent on a case-by-case basis.29. EPA seeks comment on the appropriate frequency of internal and external MITs for GS injection wells, the appropri ate types of MITs, and how to optimize

MIT methods for GS. EPA Notice 43514. A five-year frequency to conduct and revi ew internal and external mechanical integrity is appropriate. A standard pressure test utilizing a fluid compatible with the annular fluid is widely practic ed but other methods should be available. More frequent testing or review could be requi red based upon specific factors.

30. EPA seeks comment on the requirement for monitoring of GS sites for the purpose of tracking the location of the CO2 plume and associated pressure front

over time. EPA Notice 43514. Monitoring of the carbon di oxide plume is appropriate however caution is advised with respect to requiring monitoring wells since these may provide a conduit for unwanted migration. 4D seismi c and predictive models will improve over time due to iterative processes.

31. EPA’s proposal would require that owners or operators perform a pressure

fall-off test at least on ce every five years. EPA seeks comment on the use and frequency of pressure fall-off te sting for GS wells. EPA Notice 43515. An initial pressure fall-off test could be required and subsequent tests required at

the time the AOR is reevaluated.

32. Based on information evaluated to date, EPA believes that tracking the plume and pressure front is an important companion step to address any

uncertainties associated with initial Ao R modeling and requests comment on this approach and more efficient alternatives that may be used to track the plume and pressure front. EPA Notice 43516. Tracking the plume and pressu re front will allow for verification of the reservoir model. Pressure transient testing and seis mic techniques may be useful alternatives.

33. EPA seeks comment on the appropriate amount and types of monitoring that should be conducted at a GS site. Sp ecifically, EPA seeks comment regarding

the usefulness of indirect geophysical monitoring and surface air and soil gas monitoring. In addition, EPA seeks comme nt regarding the use of a Directorapproved monitoring plan fo r GS sites. EPA Notice 43517. Monitoring techniques should be determined on a site-specific basis and be based upon potential risks posed by the project and t he cost versus benefit of monitoring.

34. EPA is proposing that permit applicatio ns for GS sites include several plans not currently required under existing UI C regulations. These plans include a monitoring and testing plan, an AoR and corrective action plan, and a postinjection site care and site closure plan . EPA seeks comment on the merits of requiring plans for monitori ng, AoR, and post-injection site care as part of a permit application. EPA Notice 43517. Allowing for different plans would be mu ch more effective than prescriptive regulations; however, a plan modification should not be considered a major permitmodification. Caution needs to be taken when monitoring the injection formation due to the artificial penetration of the confining zo ne to gain data. The number of monitoring wells should be decided on a case-by case basis . It is unclear how monitoring wells will be regulated since they are not injection wells . The timing of plan submittal should be linked to the activity being addressed. Si te closure plans, post-closure plans, well plugging plans, etc., should not be required many years in advance since conditions, understanding of the seques tration zones, and technology change over time.

35. EPA seeks comment on the freq uency of all proposed reporting requirements. EPA Notice 43517. Reporting frequency should coincide with r equirements for existing UIC injection well classes unless there is a need for more frequent reporting.

36. EPA seeks comment on the requireme nt for electronic reporting in its proposed rule. EPA Notice 43518. Electronic reporting should not be require d. State systems may already be in place to collect data but may not be com patible with sending or receiving systems.

37. In addition to the above recordkeeping and reporting requirements, EPA considered a requirement for owners or operators of GS sites to provide an annual report during the lifetime of the project, including the post-injection period, regarding the GS operation. Although EPA has not included a requirement for this report in its pr oposal, EPA seeks comment regarding the necessity for such an annual report. EPA Notice 43518. During the active injection phase of a project, reports and frequencies similar to

those which exist in other UIC classes sh ould be sufficient. Once active injection ceases, an annual repor t may be appropriate.

38. EPA is proposing using a combination of fixed timeframe and a performance

standard as described above. EPA is tentatively proposing a post-injection site care (monitoring) period of 50 years with Director’s discretion to change that period to lengthen or shorten the 50-year period if appropriate. EPA requests comment on the proposed use of a tentati ve 50-year fixed timeframe that could be

modified at the Director ’s discretion based on moni toring and modeling data.

EPA Notice 43519. A performance-based time period is appropr iate rather than a fixed timeframe.

39. EPA is requesting comments on th e proposed requirements for well plugging, post-injection site care, and site closur e, including the proposed requirements for the post-injecti on time period. EPA Notice 43520. A performance-based time period is appropr iate rather than a fixed timeframe.

40. In addition, EPA seeks comment on wh ether the Director should be allowed to shorten the timeframe based on performance information, and whether EPA should require a shorter or longer post inj ection period if data suggests the time frame should be adjusted. EPA Notice 43520.A performance-based time period is appropr iate rather than a fixed timeframe.

41. Current UIC guidance describes trust funds as a form of financial assurance. The owner or operator may deposit funds into the trust fund in phases; that is, either over the term of the initial permit or over the remaining operating life of the injection well, as estimated in the well pl ugging plan, whichever period is shorter. Because of the possibility that the owne r or operator may face financial distress prior to the trust being fully funded, EPA is considering a guidance approach that would recommend adopting a pay in period of three years for GS projects, consistent with other similar progr ams in the Agency. EPA Notice 43521. The pay-in period should coincide with the estimated risk.

42. Current UIC regulations for Class I ha zardous waste inject ion allow for the use of insurance for purposes of demonstrating financial responsibility. However, insurance was not in cluded as part of the guida nce provided for Class II injection because this insurance mechanism was and still is, rarely used for the purpose of demonstrating financial assura nce for injection wells. EPA is assessing whether to provide guidance on the use of insurance providers and, if so, whether to update eligibil ity requirements for insurers for GS wells consistent with other current Federal ag ency practices. EPA Notice 43521.

Financial assurance should be left to state lawmakers and t he regulating agency and should not be a prescribed mechanism.

43. EPA is assessing whether a financial ratings threshold for all companies using a self-guarantee, similar to tho se used by other Federal agencies, is appropriate. The Agency also is consid ering what constitutes an appropriate financial rating threshold, and whether a financial rating greater than BBB or Baa (i.e., the current rating threshold est ablished under the UIC regulations) is appropriate for GS wells. EPA Notice 43522.

Financial assurance should be left to state lawmakers and t he regulating agency and should not be a prescribed mechanism.

44. EPA is requesting comments on whether financial responsibility

mechanisms to be recommended in EPA guidance should be adjusted in the manner described, whether additional instruments should be included, and whether other adjustments to the financ ial responsibility mechanisms should be considered, all subject to EPA’s authority under the SDWA. EPA Notice 43522.

Financial assurance should be left to state lawmakers and t he regulating agency and should not be a prescribed mechanism.

45. The Agency is also requesting comment on allowing separate financial

demonstrations to be submitted for the plugging of the injection well and for the post-injection site care requi rements. EPA Notice 43522. This seems a sensible approach however; financial assurance should be left to the regulating agency and not prescribed.46. EPA requests comment on adopting the existing requirements for public participation at 40 CFR Part 25 and 40 CFR Part 124 and whether additional requirements should be included to reflect the availability of new tools for disseminating and gathering information. Such tools include cable networks, the Internet, and other new technology. EPA Notice 43523. Public participation require ments should be left to the regulating agency and not prescribed. Requirements could mirror the agency’s existing public notice and participation requirements.

47. EPA also requests comment on ways to enhance the public participation process, including engaging communities in the site characterization process as

soon as candidate locations are identified. EPA Notice 43523. Public participation requirements shoul d be left to the regulating agency and not prescribed. The applicant s hould be allowed to do some si te characterization to assess site suitability and project feasibility befor e the public is engaged. Requirements could mirror the agency’s existing public notice and par ticipation requirements.

48. To gain authority for Class VI wells, St ates, Territories, a nd Tribes will be required to show that their regulations are at least as stringent as, and may be more stringent than, the proposed mi nimum Federal requirements (e.g., inspection, operation, monitoring, and r ecordkeeping requirements that well owners or operators must meet). Such Primacy States, Territo ries, and Tribes are

authorized under Section 1422 of the SDWA. EPA Notice 43523. Partial primacy should be granted for Cl ass VI wells independently of other well classes and through a process similar to gr anting primacy under ex isting UIC classes, allowing the states to determine the appropria te regulating agency.

49. There may be benefits to parsing out primacy for Class VI wells, however

EPA has not made a decision on this. A llowing States, Territories, and Tribes to acquire primacy for only Class VI wells may encourage them to assume the responsibility of implementation and provid e for a more comprehensive approach to managing CCS projects (e.g., captu re, transportation, and geologic sequestration). EPA is seeking co mment on the merits and possible disadvantages of allowing primacy appro val for Class VI wells independent of

other well classes. EPA Notice 43523. Partial primacy should be granted for Cl ass VI wells independently of other well classes allowing the states to determine t he appropriate regulating agency. This will encourage states to apply for primacy.

50. EPA proposes that Class VI injection well permits would be issued for the operating life of the GS project including the post-injection site care period. EPA

seeks comment on the merits of th is approach. EPA Notice 43523.

This will reduce administrative burdens that would yield little or no environmental

benefit.51. The Agency assumes three monitori ng wells per injection well for the purpose of estimating national costs; ho wever, the Agency recognizes that operators and primacy agency Directors may choose more or fewer monitoring wells depending on project site character istics. Because the monitoring wells and associated costs represe nt a significant component of the Cost Analysis, the Agency acknowledges that this factor may be significant in the overall uncertainty of the Cost Analysis. EPA requests comment on whether three monitoring wells per injection well is an appropriate costing assumption. EPA

Notice 43527. The number of monitoring wells r equired will be very site specific.

52. The public is invited to submit co mments or identify peer-reviewed studies

and data that assess the effe cts of early life exposure to changes in drinking water quality that may be caused by geologic sequestration of carbon dioxide.

EPA Notice 43531. There are no known unique characteristics of carbon dioxide injection or its potential impacts on USDWs t hat have not been addressed withi n existing UIC rules or found in current carbon dioxide injection projects.The North Dakota Industrial Commission, Oil and Gas Division offers the following comments on the proposed regulat ions for the underground injection of carbon dioxide for geologic sequestration:

144.6 Class VI wells are to be limited to in jection beneath the lowermost formation containing a USDW. This arbitrary exclusio n would eliminate a vast number of potential sequestration zones. Enhanced oil and gas recovery oper ations above the lowermost USDW have been taking place for a very long time. Exclusion of these zones where other abundant supplies of freshwater are available may unnecessarily limit sequestration options. These situations are best handled locally where all the pertinent regional geologic factors c an be considered. The buoyancy of carbon dioxide suggests this in an unnecessary restriction since it would move injectate away from the USDWs below the sequestration zone.

144.36 Permits for Class VI wells should be effective indefinitely, until the well is plugged.

146.81(d) Geologic sequestration project should be redefined as follows: Geologic sequestration project means an injection well or wells used to emplace a carbon dioxide stream into an injection zone for geologic sequestration. Geologic sequestration projects should not be limited to beneath the lowermost formation containing a USDW.

146.82(a) Overlying formations needs to be defi ned. Geologic information should be limited to the injection and confining zones.

Capillary pressure is difficult to measure out side a lab and would not be available if no wells have been drilled in a pr oject. Do not see necessity for this

information.

146.82(g) Baseline geochemical data on subsurface formations is too broad. Should be limited to the injection z one, confining zones, and possi bly the next porous and permeable zone above the upper confining zone.

146.82(u) Site closure plans, post-closure plans, well plugging plans, etc., should not be required many years in advance since cond itions, understanding of the sequestration zones, and technology change over time.

146.83(a)1 An injection zone capable of receivi ng the total anticipated volume of

carbon dioxide should not be an absolute requirement. The volume to be injected may be difficult to ascertain since the life of a power plant or other source may change with advances in technology or under certain ec onomic conditions. A candidate injection

zone should not be excluded if it can only serve as a sequestration zone for a portion of a project.146.83(b) Delete reference to identification of additional confinin g zones. This implies this will be required. Redundant conf ining zones are not required in other UIC

well classes.

146.85(b) The frequency specified for written updates of adjustments to cost

estimates should coincide wit h the AOR reevaluation.

146.86(b)1(v) How is corrosiveness measured?

146.86(b)2 Requiring setting surface casing below the lowermost USDW would preclude injection above the lo wermost USDW, which as earli er stated, would eliminate a vast number of potential sequestration zones. Enhanced recovery operations above the lowermost USDW have been taking place for a very long time. Exclusion of these zones where other abundant supplies of freshw ater are available may unnecessarily limit sequestration options. These situations are best handled locally where the regional geologic factors can be considered. Setting the surface casing below the lowermost USDW may not be technically feasible.

146.86(b)3 Cementing of the long-string casing to surface may not be desirable in all

situations; an annulus that c an be monitored may be desirable. The long-string casing

should be cemented to at least above the upper confining zone.

146.86(b)5 Request clarification whether a CBL with VDL image is sufficient.

146.86(c)2(ii) How is corrosiveness measured?

146.87(a) Relevant geologic formations is too br oad. This information should only be required for the injection and confini ng zones and possibly the next porous and permeable zone above the upper confining zone.

146.87(a)2 Open hole logs in the surface hole are unusual and not necessary. If required, certainly not in every well in a project.

146.87(a)3 Should specify basic logging requirement not specific logs.

146.87(b) Coring should not be required if an adequate core and report exists for a nearby well. Coring should onl y be required of the injection and confining zones and possibly the next porous and permeable zone above the upper confining zone.

146.87(d)2 Vague and ambiguous.

146.87(f) Unrealistic time frame. Tie initia l reporting to spud date and 48 hour

notification thereafter.146.88(c) Pressure on the annulus is not necessary in all situations. Maintaining pressure above the injection pressure will subject the long -string casing to unnecessary

stress and is not commensurate with the risk associated with carbon dioxide injection.

146.88(e) Is continuous recording of annular fl uid volume possible or practical?

Requiring down-hole shut-off valves ma y be problematic. To protect the entire tubing-casing annulus they would need to be installed at or below the injection packer. This may make the tool prone to failur e. These valves may restrict or preclude the running of down hole moni toring or logging tools. In clusion of a seating nipple directly above the injection packer which woul d allow the installation of a wire line set plug may be more appropriate.

146.89(c) Annual tracer surveys, temperature or noise logs, or casing inspection logs is too burdensome. This frequency should coincide with AOR reevaluation.

146.90(b) Is continuous recording of annular fl uid volume possible or practical?

146.90(c) Quarterly is too onerous. Director should have discretion to require less frequently based upon performance.

146.91(a) Injection volumes and pressures should be reported monthly.

146.91(c) Electronic reporting should not be requi red. State systems may already be in place to collect data but may not be co mpatible with sending or receiving systems.

146.92(d) Simplify. Plugging reports should be required within a consistent time

frame.

146.93(b) A performance-based time period is appropriate rather than a fixed timeframe. Establishing an arbitrary and long time frame will i nhibit operators from entering into this activity.

Respectfully submitted,

Mark Bohrer Petroleum Engineer/UIC Manager

North Dakota Industrial Commission

Oil and Gas Division 600 E Blvd-Dept 405

Bismarck ND 58505-0405 mbohrer@nd.gov (701) 328-8020Letter ID: 0241

Commenter: Mark Bohrer Organization: North Dakota Industrial Commission

Letter ID: 0241 Comment ID: 23223 Letter Lines: 22 to 33

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

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

Comment: 1. EPA seeks comment on any aspects of th e ongoing State efforts to regulate the GS of CO2 and how these efforts might be used to better inform a final Federal rulemaking. EPA Notice 43497.

The North Dakota Industrial Commission ha s drafted legislation concerning capture and storage of carbon dioxide to be acted upon during the upcoming legislative session in January 2009. This legislation was crafted using the IOGCC model. If the legislation is en acted, administrative rules will be promulgated. As with most regulatory progr ams, the states are best qualified to take state-specific issues into account and to tailor the regu latory needs to fit their unique circumstances. To this e nd, partial primacy for Class VI wells is imperative.

Individual Response: EPA agrees that states should be al lowed to obtain primacy for Class VI wells independently of other well classes, and wi ll allow independent primacy for Class VI wells under §145.1(i) of the final GS rule. In the past , EPA has not accepted UIC primacy applications

for individual well classes unde r Section 1422 of SDWA. In other words, if a State wanted primacy for Class I wells, the State would also ne ed to accept responsibilit y for Class III, IV, and V wells. This policy has been in place since the initiation of the UIC Program in the early 1980s and was intended to encourage states to take full responsibility fo r UIC programs, avoid duplication of efforts, and provide for administrative efficiencies.

However, given the potential for CCS (encom passing capture, transportation, and geologic sequestration) to be an important part of a na tional priority to address climate change, EPA believes that providing states the flexibility to obtain primacy for Class VI wells independently of other well classes can help foster effective management of CCS. EPA believes that allowing independent Class VI primacy may encourage states to take res ponsibility for implementation of Class VI regulations and provide for a more co mprehensive approach to managing CCS projects by promoting the integration of GS activities under SDWA in to a broader framework for managing CCS. Furthermore, GS operations involve ancillary activities (e.g., pipeline operations, pore space ownership, land use rights, and surface access) for which states can call upon other authorities that exist at the state leve l (but outside UIC author ity) to provide a more comprehensive CCS management approach.

The Agency believes that it is important for stat es to use their unique e fficiencies to promote adoption of this burgeoning and important tec hnology, while assuring that USDWs are protected

1from endangerment through the UIC regulatory framework. EPA believe s that, due to the importance of implementing an effective, comprehensive, and seamless CCS program, States should be provided the flexibility to obtain primacy for Class VI only.

EPA also believes that allowing states to apply only for Class VI primacy will shorten the primacy approval process for states. EPA's willingness to accept independent primacy applications for Class VI wells represents a shift in its longstandi ng policy of discouraging "partial primacy." It is very important to note that this shift in policy allowing for Class VI primacy does not apply to any other well Cl ass under Section 1422. EPA will continue to discourage applications for pa rtial primacy for all other well types under Section 1422.

EPA clarifies that states should be able to obtain primacy for Cla ss VI wells independent of other well classes provided they devel op regulations that are at leas t as stringent as the minimum Federal requirements (e.g., permitting, inspec tion, operation, monitoring, and recordkeeping requirements) provided in the final GS rule. EPA believes that existing programs can adapt their expertise to the new requirements for Class VI wells and will be able to develop a primacy application for Class VI wells under section 1422 of SDWA and en sure that their GS programs integrate into national climate change priori ties and protect USDWs from endangerment.

EPA recognizes that some states have already begun legislative e fforts that are wider in scope

than the Federal GS rule and believes that allo wing Class VI primacy (i ndependent of other well classes) may encourage states to take responsibility for implemen tation of a more comprehensive approach to managing CCS proj ects (e.g., capture, transportati on, and geologic sequestration).

Letter ID: 0241 Comment ID: 23224 Letter Lines: 35 to 46

Comment Code: 2046 1.5.2.3 Continuing to classify CO2 in jection for EOR/EGR as Class II/ dividing line between Class II and Class VI (seeking comment)

Comment: 2. Injection of CO2 for the pur poses 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 me rits of this appro ach 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 43502.

This approach makes the most sense since enhanced recovery operations have proven successful at increasing and ma ximizing oil and gas recovery while successfully sequestering carbon dioxide. As long as production of oil and gas is occurring, it would be inefficient a nd confusing to change the rules and processes under which thes e wells are regulated.

Individual Response: EPA agrees that injection of CO2 for the primary purpose of enhancing oil and gas recovery should remain under the Cl ass II Program. The Agen cy believes that the nature and risks of CO2 inject ion for the primary purpose of l ong term storage poses different

2risks than injection for the primary purpose of EOR, and therefore has developed new Class VI regulations to address these unique risks. For example, the volu me of CO2 anticipated to be injected for long term storage is significan tly greater than for EO R operations. Reservoir pressure conditions will also be different, with Class VI injection ope rations involving large volumes of CO2 and likely having higher pressures w ithin their storage formations than Class II EOR projects.

The final Class VI regulations re quire that any owner or operato r injecting CO2 for the primary purpose of long term storage obtain a Class VI pe rmit with some special consideration for the fact that they are transitioning from a well not or iginally designed to meet Class VI requirements. The Director has the authority to determine at wh at point a Class VI permit is required for those projects that are transitioning from the primar y purpose of EOR to long term storage of CO2. The final regulation provides a set of technical factors for the Direct or to evaluate in making this determination, at §144.19. EPA believes that this approach provides su fficient protection of

USDWs when there is an increased risk to USDWs as compared to traditi onal Class II operations while allowing for site-specific flexibility.

EPA is developing guidance on transitioning perm its from Class II to Class VI. The guidance will assist Directors in determining whether an injection project should be transitioned from Class II where the primary purpose is oil and gas production to Class VI where the primary purpose is long-term storage of large volumes of CO2. The guidance describes recommended methods the Director may use to evaluate change s in risk to USDWs from projects, and how the Director may determine whether a project should be regulated within th e Class II or Class VI UIC program. This guidance will be available on EPA’s website at http://water.epa.gov/type/groundwat er/uic/wells_sequest ration.cfm. For more information, please

see the discussion on transition of Class II well s in the preamble to the final GS rule.

Letter ID: 0241 Comment ID: 23225 Letter Lines: 48 to 65

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

Comment: 3. EPA seeks comment on the approach to grandfather construction requirements at the Director’s discretion for existing Class I, Class II, and Class V wells seeking to convert to Class VI wells , and whether additional construction requirements would be necessary to prevent endangerment to USDWs from the GS of

CO2. EPA Notice 43502.

If a well has been utilized for inject ion and is properly constructed under existing regulations, it is constructe d to prevent the mi gration of the injectate into a USDW. The demonstrated well performance is indicative that well construction is protective of USDWs. A review to verify the existing construction as protective is sufficien t to grandfather the construction as protective as a Class VI injection well.

4. Additionally, EPA seeks comment on how the grandfathering approach for existing wells may affect compliance with the other requirements in its

3proposal. EPA Notice 43502.

See 3 above.

Individual Response: EPA agrees that many Class I, Cl ass 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 en gineered 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).

Following re-permitting of the well as Class VI, thes e projects must be subject to the operational, MIT, monitoring, reporting, plugging, and post-inject ion site care and site closure requirements

in the final GS rule. See the discussion of EPA's fi nal regulatory approach in the preamble to the GS rule for additional detail on these requirements.

Letter ID: 0241 Comment ID: 23226 Letter Lines: 67 to 80

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

Comment Code: 4430 2.4.4.3.3 Injection into coal seams above USDWs (seeking comment)

Comment: 5. EPA is proposing to preclude the injecti on of CO2 for long-term storage into coal seams where they are above the lo wermost USDW. EPA requests comment on this proposed prohibition. EPA Notice 43503.

This arbitrary exclusion would eliminate a vast number of potential sequestration zones. Enhanced recovery ope rations above the lowermost USDW have been taking place for a very long time. Un mineable coals in North Dakota are found in high clay content glacial till which, if unfractured, serves as an excellent confining zone. Based upon carbon dioxide’s affinity to adhere to coals, it is unwise to arbitrarily elim inate a potentially large number of sequestration zones. Exclusion of thes e zones even in areas where other abundant supplies of freshwater are avai lable may severely limit sequestration options. These situations are best handle d locally where all of the pertinent regional geologic factors can be considered.

Individual Response: EPA acknowledges that site-suitability for GS is dependent on a number of factors and that many formation types may be suitable for GS. The final GS rule does not preclude injection into unmineable coal seam s (or any formation type) provided owners or operators can demonstrate that GS can be pe rformed in a manner that protects USDWs from endangerment based on requirements under today’s rulemaking. The Agency anticipates that in

the near-term, most GS in unmineable coal seams will continue to be experimental. Such projects may be permitted as Class V experimental technology wells if they are of an experimental nature (i.e., to test GS technologies and collect data). EPA will continue to review data on early GS projects, including those in unmineable coal seams, to determine whether the appropriate amount and types of information and documentation are required and being collec ted. EPA plans, every

4six years, to collect and review data on GS pr ojects 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.

EPA recognizes that GS in unmineable coal seam s has been the subject of less research than saline formations or depleted oi l and gas reservoirs. However, EPA has examined select field projects involving injection into unmineable co al seams, including the Pump Canyon Site, near

Archuleta, New Mexico. In the Notice of Data Availability and Reque st for Comment, EPA described research at the Pump Canyon site where the Southwes t Partnership is studying CO2 injection into deep, unmineable coal seams and pe rforming a "seal analysis" of the ability of the

Kirtland Formation to act as a barrier to the m ovement of CO2 or othe r reservoir fluids. EPA continues to follow this projec t, recently completed projects, and ongoing GS projects injecting

into unmineable coal seams. Other coal seam in jection projects are underway through the RCSPs

in the Illinois Basin, Black Warrior Basin, and Central Appalachian Basin.

EPA clarifies that the final rule requires that injection for GS be into non-USDWs below the lowermost USDW; however, owners or operators may apply for a waiver from this requirement, as described in §146.95. For more information, see the discussion of waivers in the preamble to

the final rule.

Letter ID: 0241 Comment ID: 23227 Letter Lines: 82 to 93

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

USDW

Comment: 6. The location and proximity of other fo rmations 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 43503.

This arbitrary exclusion would eliminate a vast number of potential sequestration zones. Enhanced oil and gas recovery operations above the lowermost USDW have been taking place fo r a very long time. Exclusion of these zones where other abundant supplies of freshwater are available may unnecessarily limit sequestration options. These situations are best handled locally where all the pertin ent regional geologic fact ors can be considered. The buoyancy of carbon dioxide suggests this in an unnecessary restriction since it would move injectate away from th e USDWs below the sequestration zone.

Individual Response: EPA acknowledges that there are lim ited circumstances where injection above the lowermost USDW can be performe d in a manner that protects USDWs from endangerment, as long as appropriate protections are in place. The final GS rule at §146.95 establishes a process by which owne rs or operators can seek a waiv er of the Class VI injection depth requirements for inject ion into non-USDW formations above and/or between USDWs. Additionally, the final GS rule doe s not categorically preclude or prohibit injection into any type

of formation.

5EPA believes that these requirements will ensure USDW protection while providing flexibility to UIC program Directors and owne rs or operators who undertak e CO2 injection for GS. The Agency believes this approach: 1) responds to co ncerns about local and re gional geologic storage capacity limitations imposed by th e proposed injection depth require ments; 2) allows for a more site-specific assessment of injection depth for GS projects; 3) accommodates injection into different formation types; 4) a llows for injection of CO2 for GS into non-USDWs above and/or between USDWs when appropriate and where it can be demonstrated that USDWs will be protected; and 5) responds to concerns about the use of aqui fer exemptions for GS. Finally, EPA’s approach to addressing injection depth va riability through a waiver process responds to concerns about future drinking wa ter resource availability and the need to ensure that high quality water remains available in sufficient qua ntities to supply drinking water needs. For additional information on the waiver approach, pleas e see the final rule and preamble, as well as EPA's responses to comments on the Notice of Data Availability and Request for Comment.

Letter ID: 0241 Comment ID: 23228 Letter Lines: 95 to 110

Comment Code: 1614 1.3.1.2 Impurities in captured CO 2; purity standards for CO2

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

Comment: 7. By defining "carbon dioxide stream" to exclude hazardous wastes (146.81(d)),

EPA’s rule, if finalized, assures that it would apply only to CO2 streams that

are not hazardous wastes as defined in 40 CFR Part 261. As a result, EPA’s proposed rule would preclude the injec tion of hazardous wastes in Class VI injection wells. EPA seeks comment on this approach and other considerations associated with the presence of "impur ities" in the CO2 stream. EPA Notice

43503.

The presence of certain hazardous wastes should not preclude the overall carbon dioxide stream from injection into a sequestration zone. The process of removing the carbon dioxide and making it suitable for transportation and injection should render it relatively pure . The presence of impurities can be dealt with at a specific source and th e overall waste stream certified for injection. If the well constr uction and geologic setting is suitable to confine the carbon dioxide stream and prevent its migration into a USDW, then certain impurities and/or hazardous wastes should be allowed.

Individual Response: EPA recognizes that many CO2 str eams may be relatively pure, and

research indicates that the estimated amounts of impurities in a CO2 stream are likely to be low.

However, these estimates are based on limited in formation, and uncertainties remain about the expected concentrations of impurities from the va rious types of CO2 streams. The concentrations

of minor and trace elements in CO2 streams for GS projects are likely to vary by facility, coal composition, plant operating conditions, and polluti on removal technologies. For this reason, the GS rule requires the owner or ope rator to submit data about the site , including an analysis of the chemical and physical characteristics of the CO 2 stream, as required at §146.82(a)(7)(iv), and information on the compatibility of the CO2 stream with fluids in the injection zone and minerals

6in both the injection and the confining zones and the materials used to construct the well, per §146.82(c)(3). This information can help the Director determine the pote ntial for geochemical reactions between the injectate (CO2) and the host geologic formations, whic h could result in the plugging of pore spaces or the disso lution of formation minerals.

EPA received many comments regarding the applicab ility of the RCRA regulations and statute to CO2 streams that are geologically sequestered under the final Cl ass VI UIC well requirements. As a result, EPA has decided to initiate a sepa rate proposed rulemaking specifically to examine the issue of RCRA applicability to CO2 stream s being geologically sequestered, including the possible option of a conditional exemption from the RCRA requirements for CO2 GS in Class VI wells. EPA will consider these comments as pa rt of its development of that proposal. The Agency will consider issues particular to RCRA in the context of that separate rulemaking, and recommends that the commenter read that propose d rule when it is published. The Agency notes

that commenters who wish to submit comments on the RCRA proposal will need to do so during the comment period for that rule. Finally, EPA also notes that the final GS rule, which adds new regulations for Class VI wells under the Safe Drinking Water Act (SDWA), is not making any changes to the RCRA regulations.

Letter ID: 0241 Comment ID: 23229 Letter Lines: 112 to 130

Comment Code: 1640 1.3.4 CERCLA issues (seeking comment)

Comment: 8. Class VI requirements and permits will need to be carefully structured to ensure that they do not "authorize" in appropriate hazardous releases. This would include clarifying if there are poten tial releases from the well which are outside the scope of the Cl ass VI permit. EPA request s comment on particular situations where this might occur. EPA Notice 43504.

Carbon dioxide should not be classified as a hazardous waste. Carbon dioxide is

not hazardous or toxic under normal condi tions. CERCLA liabil ity will not only impact owners and operators of carbon di oxide sequestration pr ojects, but also pore space owners. Subjecting pore space owners to CERCLA liability and joint and several liability under CERCLA will greatly hamper carbon dioxide sequestration projects. EPA should take the opportunity in this rulemaking to alleviate any CERCLA liability concerns.

9. EPA also requests comment on other c onsiderations associated with the presence of impurities in the CO2 stre am related to CERCLA. EPA Notice 43504.

CERCLA should not apply to carbon dioxide sequestrati on. EPA needs to provide assurances to facilitate carbon dioxide sequestra tion projects.

Individual Response: EPA notes that the GS rule is no t promulgated under the RCRA or

CERCLA statutes, and further, th e applicability of t hose statutes will not be determined under

the SDWA or the terms of the GS rule, but rather according to those statutes themselves and any implementing regulations that may apply. To the ex tent the commenter is seeking interpretations

7of CERCLA or RCRA and its related provisions, such interpretations are beyond the scope of this rulemaking.

EPA received many comments regarding the applicab ility of the RCRA regulations and statute to CO2 streams that are geologically sequestered under the final Cl ass VI UIC well requirements. As a result, EPA has decided to initiate a sepa rate proposed rulemaking specifically to examine the issue of RCRA applicability to CO2 stream s being geologically sequestered, including the possible option of a conditional exemption from the RCRA requirements for CO2 GS in Class VI wells. EPA will consider these comments as pa rt of its development of that proposal. The Agency will consider issues particular to RCRA in the context of that separate rulemaking, and recommends that the commenter read that propose d rule when it is published. The Agency notes

that commenters who wish to submit comments on the RCRA proposal will need to do so during the comment period for that rule. CO2 itself is not listed as a hazardous substance under CERCLA however, the CO2 stream may contain a listed hazardous substance (such as mercury) or may mobilize substances in the subsurface th at could react with ground water to produce listed hazardous substances (such as sulfuric acid). Whether such substances may result in CERCLA liability from a seque stration facility depends enti rely on the composition of the specific CO2 stream and the environmental medi a in which it is stored (e.g., soil or ground water). CERCLA exempts from liability, under CERCLA section 107, 42 U.S.C. 9607, certain “federally permitted releases” (FPR) as defined in CERCLA, 42 U.S.C. 9601(10). Class VI permits will need to be carefully structured to ensu re that they prevent potential releases from the well which are outside the scope of the Class VI permit.

Letter ID: 0241 Comment ID: 23230 Letter Lines: 132 to 150

Comment Code: 3120 2.1.2 Need to identify additional confining and containment zones (seeking comment)

Comment: 10. 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 provi de additional sites for monitoring, mitigation, and remediation. EPA’s propos al would not require that these

additional zones be identifie d for all GS sites because their absence does not necessarily indicate inappropria teness of a GS site. Howe ver, if such zones are present, information about their ch aracteristics can pr ovide inputs for predictive models, identify appropriate m onitoring locations, and improve public confidence in and acceptance of a proposed GS site. EPA specifically seeks comment on the merits of requiring the iden tification of these additional zones.

EPA Notice 43506.

Redundant confining zones should not be requ ired. If the primary confining zone is adequate, by definition it is sufficient. If one sequestration site identifies one confining zone and another identifies multiples, it may lead to public confusion and lack of confidence in a site that only has one confining

8zone even though it is ju st as protective.

Individual Response: EPA retains the requirement to iden tify additional containment/confining zones, if required by the Di rector, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumst ances, and clarifies that this requirement is at

the Director's discretion, based on his or her understanding of a part icular site. EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protecti on. These layers could further impede vertical fluid movement and al low for pressure dissipation, and also provide additional sites for monitoring, mitigation, and re mediation. The Agency's decision is supported by commenters representing states, water associati ons, and an electric utility who assert that these requirements promote a flexible, risk-base d, site-specific approach to characterizing and permitting a site for GS projects, and are intende d to improve understanding of the project as a whole and promote better modeling of the site.

Letter ID: 0241 Comment ID: 23231 Letter Lines: 152 to 165

Comment Code: 3320 2.2.1.2 Comments opposed to requiring computational models to

delineate the AoR

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

Comment: 11. EPA believes that predicting the comple x multi-phase buoyant flow of the CO2, "co-injectates," and compounds that may be mobilized due to injection requires the sophistication of computational models. EPA proposes that the owners or operators of GS wells be re quired to delineate the AoR for CO2 GS sites using computational fluid flow m odels designed for the specific site conditions and injection regime. EPA seek s comment on the use of modeling for

AoR delineation. EPA Notice 43506.

There is concern about the lack of info rmation necessary to construct a valid model in areas where the sequestration z one has not been extensively studied. This lack of information may make mode ling difficult or not very useful. Any modeling used should be re-examined and r ecalibrated over time with additional data gathered. Modeling should not be sole ly relied upon where real data offers

a different view. Seismic and offset we ll data can help delineate the AOR.

Individual Response: The Agency believes that AoR delin eation using computational modeling that accounts for the multiphase flow of CO2 an d native fluids (i.e., naturally occurring salty water), including density-driven flow (i.e., buoyancy), is necessa ry to ensure protection of USDWs from endangerment. The computational m odels used for this purpose are required to predict the fate of injected CO2 and changes in formation pressure. EPA believes that the requirements at 146.84(c)(1) to delineate the AoR using computational modeling are appropriate and encompass the significant processes that co uld affect the location of the CO2 plume and associated pressure front and has re tained this in the final rule.

9EPA agrees that the modeling should be re -examined and recalibrated over time. The GS regulation at 146.84(e) also requires owners or op erators to periodically reevaluate the AoR to incorporate monitoring and opera tional data. This process provides additional opportunities to verify that the models have accurately predicte d movement of the CO2 plume and to make any needed adjustments to corrective action or monitoring at the site.

Letter ID: 0241 Comment ID: 23232 Letter Lines: 167 to 187

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

Comment: 12 In some cases, owners or operators may choose to use proprietary models (i.e., not available for free to the gene ral public). EPA says it is aware that the use of proprietary codes may preven t full evaluation of model results (e.g., NRC, 2007). Several popular codes in th e petroleum-reservoir 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 studie s to model CO2 sequestration. When using a proprietary model, owners or operators should clearly disclose the code assumptions, relevant equations, and scie ntific basis. EPA seeks comment on allowing the use of proprietary mode ls for GS sites. EPA Notice 43507.

The use of proprietary models is wide ly used and accepted in oil and gas

reservoir simulation. These models are a l ogical fit to simulate carbon dioxide sequestration projects. These models ar e verified using a history-match. The regulatory agency responsible for monito ring carbon dioxide sequestration does

not need access to the code in order to conduct or evaluate a history-match. A regulatory agency could conduct reser voir modeling using its own modeling software to compare. Elimination of thes e widely used and un derstood reservoir models would be unwise. The assumptions and equations used in the modeling along with a valid history match will provide the regulating authority the ability to assess the model’s accuracy.

Individual Response: EPA agrees with commenters that av ailable proprietary models may meet the complex needs for calculating the AoRs of GS sites, and shar es their concern about the need to evaluate the inputs and assumptions used. EP A 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 satisf action, the code assumptions, relevant equations,

and scientific basis. EPA adds that its Confid ential Business Information requirements at 40 CFR 144.5 will apply to the use of proprietary models.

EPA acknowledges that several proprietary m odels are currently, successfully used by petroleum-reservoir engineering professionals as well as in peer-reviewe d studies to model CO2 sequestration.

10Letter ID: 0241 Comment ID: 23233 Letter Lines: 189 to 193

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

Comment: 13. EPA seeks comment on the applicability of computational fluid flow models for delineating the AoR of GS sites. EPA Notice 43507.

The use of computational flow models is appropriate, however; modeling should

not be the sole criteria to determine th e AOR if actual measured data exists.

Individual Response: EPA agrees that a detailed geologic a ssessment is essential to evaluating the presence and adequacy of a proposed site to receive and confin e the CO2. The AoR and corrective action plan required at §146.84(b) must describe the site ch aracterization data on

which the model will be based. The Director has discretion to require the use of existing data if it is not initially included.

EPA clarifies that the model i nputs must include act ual geologic information, data collected during the site characterization process (e.g., information about artificial penetrations), and anticipated operating parameters (e.g., injection rates) submitted with the permit application under §146.82. Models will be revised and recalibr ated during subsequent AoR reevaluations,

which must account for all avai lable monitoring and operational data, as required at §146.84(e).

The Agency believes that predicting the comp lex multiphase buoyant flow of the CO2, coinjectates, and compounds that may be mobilized due to injection require s the sophistication of computational models. Models can predict CO2 fate and transport, as well as changes in formation pressure, in three dimens ions, as a function of time in or der to delineate the subsurface storage site and the AoR. Models can account fo r site-specific and pred icted operating conditions as well as geologic heterogeneities and potential migration through faults, fr actures, and artificial penetrations.

Letter ID: 0241 Comment ID: 23234 Letter Lines: 195 to 201

Comment Code: 3530 2.2.3.1 AoR reevaluation fre quency (seeking comment)

Comment: 14. EPA seeks comment on requiring the reevaluation of the site AoR on a periodic basis, under what conditions th e AoR should be reevaluated, and the appropriateness of a 10-year minimum fixe d frequency for AoR reevaluation. EPA

Notice 43507.

It is appropriate to reevaluate the AOR on a periodic basis. The conditions and frequency under which the AOR is reev aluated should be based upon monitoring.

Individual Response: EPA agrees that site-specific factor s, including monitoring data, should

11be considered in the reevaluation schedule, a nd notes that the AoR a nd corrective action plan must specify the site-specific monitoring and ope rational conditions that warrant reevaluation, as specified in §146.84(b)(2)(ii). In addition, the Direct or has discretion to require more frequent

AoR reevaluation if he or she ha s reason to believe, based on s ite-specific information, that a five-year reevaluation schedule is not sufficiently protective of USDWs. However, EPA believes that setting a minimum reevalua tion frequency is appropriate. In the final rule, the Agency changed the minimum frequency for the AoR reev aluation at §146.84(e) from 10 years to 5 years

in the final GS rule. EPA believes that this re vised frequency addresse s commenters' concerns

about the inherent un certainties in modeling CO2 moveme nt, the emerging nature of GS technology, risk-based targeting of monitoring activities, and th e unique nature of CO2 GS.

Letter ID: 0241 Comment ID: 23235 Letter Lines: 203 to 217

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

Comment: 15. EPA proposes to allow a phased approach to corrective acti on 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 a nd site conditions. EPA invites public comment on the merits and frequency of r eevaluation of the AoR as well as the phased corrective action approach for GS wells. EPA Notice 43508.

A phased approach is appropriate. Correc tive action for some aspects of the project may not be necessary at the outset and a phased approach would allow an operator to optimize capital expenditures to make a project more feasible.

Wholesale corrective action at the outset of a project ma y ultimately result in

corrective action in areas unaffected by the project. In addition, the procurement of rigs and other equipment and the time necessary to conduct corrective actions in areas that might not be affected for a significant period of time could unnecessarily dela y a sequestration project.

Individual Response: EPA acknowledges the commenter’s s upport 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, avoi ding delays in project start-up, allowing for use of future, improved corrective act ion 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. EPA clarifies that all wells in the AoR of a GS proj ect that need corrective action must receive it at some point.

Regarding the comment that some wells identified in the original AoR ultimately may not be affected by the storage project, EPA clarifies that, if monitoring or modeling data indicate a change in the AoR, the owner or operator w ould need to review and amend the AoR and corrective action plan and follow the amended plan.

12Letter ID: 0241 Comment ID: 23236 Letter Lines: 219 to 230

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

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

USDW

Comment: 16. EPA seeks comment on the proposed GS well requirements for depth of surface casing, the cementing of long-string casing, and construction with a packer set opposite a cemented interval. EPA Notice 43509.

Requiring setting surface cas ing below the lowermost USDW would preclude injection above the lowermost USDW, which as earlier stated, would eliminate a vast number of potential sequestration z ones. Enhanced recovery operations above the lowermost USDW have been taking place for a very long time. Exclusion of these zones where other abundant supp lies of freshwater are available may unnecessarily limit sequestration options. These situations are best handled locally where the regional geologic f actors can be considered. Setting the surface casing below the lowermost USDW may not be technically feasible.

Individual Response: EPA disagrees that the surface casing requirements in the GS rule preclude injection below deep USDWs. The fina l GS rule at §146.86(b)(2) requires that surface casing extend through the base of the lowermos t 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 cem ent to meet the standard that USDWs are protected from endangerment. EPA notes that th ere are many potential ways to meet the requirement, such as the use of staged cementing.

EPA recognizes concerns regardi ng construction of Class VI wells where the lowermost USDW is very deep. To further address comments on d eep 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 opera ting under injection depth waivers must comply with additional construction require ments to ensure that wells used to inject above or between USDWs are protective. See the discussion of the wa iver approach in the preamble to the final GS

rule for additional information.

EPA stresses that protection of USDWs from en dangerment, regardless of their depth or the number of USDWs in an area, is the primary mission and mandate of the UIC program and the purpose of all requirements for injection wells. A ny injection activity must be demonstrated to not endanger USDWs, regardless of their depth, and if such non-endangerment cannot be shown, the activity will not be allowed unde r UIC requirements or the SDWA.

Letter ID: 0241 Comment ID: 23237 Letter Lines: 231 to 233

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

13Comment: Cementing of the long-string casing to surface may not be desirable in all

situations; an annulus that can be mon itored may be desirable. The long-string casing should be cemented to at least a bove the upper confining zone. Requiring

Individual Response: EPA does not believe that the cem enting requirements at §146.86 would prevent monitoring, operation and remediation of Class VI wells. Cementing of deep wells has been performed successfully in the past by owners or operators of Class I hazardous and Class I municipal waste disposal wells. Some of these wells, which must meet the same cementing and casing requirements as Class VI wells, are up to 12,000 feet deep and have been successfully cemented in a manner that maintains integrity an d allows for all required well testing, operation, and remediation (EPA, 2001). See the discussion of Class VI well construction requirements in the preamble to the final GS rule for additi onal 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/gr oundwater/uic/wells_se questration.cfm.

Letter ID: 0241 Comment ID: 23238 Letter Lines: 233 to 234

Comment Code: 3826 2.3.1.3 Packer requirements (seeking comment)

Comment: casing should be cemented to at least a bove the upper confining zone. Requiring the packer be set opposite a cemen ted interval is appropriate.

Individual Response: EPA agrees that the use of tubi ng and packer in accordance with §146.86(c) will offer the best multiple-barrier pr otection 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: 0241 Comment ID: 23239 Letter Lines: 236 to 246

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

Comment: 17. EPA also seeks comment on how the pr oposed grandfathering provisions for existing wells (construction requirements) may affect compliance with the above, proposed construction requirements. EPA Notice 43509.

If a well has been utilized for inject ion and is properly constructed under existing regulations, it is constructe d to prevent the mi gration of the injectate into a USDW. The demonstrated well performance is indicative that it is protective of USDWs. A review to ve rify the construction is sufficient to grandfather the construction as protec tive as a Class VI injection well.

Additional realistic remedial actions short of new construction could be required to make the well more protective.

14Individual Response: As described above, EPA agrees that many Class I, Class II, and Class V experimental technology wells are designed and constructed to withstand exposure to CO2. The final GS rule provides for the construction of these wells to be grandfathered per §146.81(c), provided the owner or operator can demonstrate to the Director that the wells were engineered and constructed to meet the requirements at §146. 86(a) and ensure protec tion of USDWs, in lieu of requirements at §146.86(b) and §146.87(a). EPA clarifies that only the construction requirements are grandfathered and that all ot her Class VI requirements (reporting, monitoring, mechnical integrity testing, etc.) must be met following a determination under §146.81(c).

Letter ID: 0241 Comment ID: 23240 Letter Lines: 248 to 256

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

Comment: 18. EPA seeks comment on the merits of hor izontal well drilling techniques for GS wells and the applicability of well c onstruction requirements discussed in this proposal. EPA Notice 43509.

Horizontal wells should be allowed. The drilling of these wells has become

common in certain basins. Their use woul d maximize injection while minimizing the surface footprint and injection pre ssure. Well construction requirements

should be similar to vertical wells i. e., the vertical portion of the well should be cemented to above the upper confining zone.

Individual Response: In this final rule, EPA allows the use of horizontal wells at GS projects. In the proposed rule, EPA sought comment on the appr opriateness of horizontal drilling techniques for Class VI wells, and commenters representing energy companies, el ectric utilities, the oil and gas industry, CCS associations, states, and the public, unanimously suppo rted the concept and provided many reasons why horizonta l wells could be beneficial at GS sites. Based on an evaluation of these comments and additional research by EPA, the Agency has concluded that horizontal wells that are properly constructed, logged, and tested for mechanical integrity (i.e., to meet the requirements of the GS rule) can ensu re the protection of USDW s from endangerment.

Letter ID: 0241 Comment ID: 23241 Letter Lines: 258 to 268

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: 19. EPA seeks comment regarding requireme nts for degradati on-resistant well

construction materials, such as acid-res istant cements and co rrosion resistant casing. EPA Notice 43510.

Based upon history in carbon dioxide injection projects, construction requirements should be based upon actual n eeds as identified in these projects

15and upon actual subsurface conditions. Indus try experience with carbon dioxide EOR projects supports the use of conve ntional tubing, casing, and cements.

These wells have been demonstrated to protect USDWs. Corrosion mitigation measures such as lined tubing, use of corrosion inhib itors, and proper dehydration of carbon dioxide pr ovide adequate protection.

Individual Response: EPA recognizes that the oil and gas industry has decades of experience injecting CO2 for the purpose of enhanced reco very, and that this practice has led to the development of many corrosion mitigation measures that would be appropriate for the design of Class VI wells. The rule does not specify material s to be used; rather, it provides owners or operators with the flexibility to choose, as l ong as the materials used in Class VI wells are compatible with fluids with which they may co me into contact and meet or exceed standards developed for such materials by API or ASTM In ternational, or comparable standards approved by the Director, as provi ded at §146.86(b)(1).

EPA believes, however, that casings and cement a nd other materials used must have sufficient strength and be designed for the life of the se questration project. That is, corrosion mitigation measures, as suggested by the commenter, alone are not sufficient to protect USDWs. For this reason, the rule requires that mate rials meet standards established in the rule and be compatible

with fluids with which the materials ma y be expected to come into contact.

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: 0241 Comment ID: 23242 Letter Lines: 270 to 277

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

Comment Code: 4130 2.4.1.3 Appropriateness of using fractur ing for well stimulation (seeking comment)

Comment: 20. EPA is requesting comment on the ex tent and scope to which hydraulic fracturing should be allowe d during GS injection and whether the use of fracturing for the purposes of well s timulation is appropriate. EPA Notice

43511.

Hydraulic fracturing should be allowed as long as it does not compromise the confining zone. Computer modeling to predict the fracture growth can be

utilized in fracture stimulation design.

Individual Response: EPA agrees that stimulation, such as hydraulic fracturing should be permitted in some situations, and the final rule a llows the use of hydraulic fracturing at GS sites, where approved by the Director. Hydraulic fracturing is one of several stimulation technologies available to improve wellbore and formation injec tivity. EPA clarifies that fracturing is permitted during stimulation, but not during injection. During injection, the injection pressure must not

16exceed 90 percent of the fracture pressure, as specified in §146.88(a).

All stimulation, including hydraulic fracturing, must be approved by th e Director. Owners or operators must submit a proposed stimulation program as part of the permit application under §146.82(a)(9); the plan must demonstrate that any stimulation activities will not compromise the integrity of the confining zone. The Director wi ll evaluate the owner or operator's proposed stimulation plan in the context of all information about the site , and the owner or operator must perform stimulation only as approved. It is possi ble that computer simulations may support this

determination to the Director's satisfaction. EPA clarifies that all data submitted with the permit application, including modeling of the AoR, w ill inform the Director's decision on whether hydraulic fracturing is accep table at a GS site.

Letter ID: 0241 Comment ID: 23243 Letter Lines: 279 to 286

Comment Code: 4140 2.4.1.4 Use of fracturing for GS in specific geologic settings (seeking comment)

Comment: 21. EPA is also requesting information to better qualify the use of fracturing for GS injection in specific geologic se ttings and rock formation lithologies.

EPA Notice 43511.

This type of information needs to be obtained from industry. Many basins have implemented hydraulic fracturing of certain formations for a nu mber of years. These situations are best handled locally where the regional geologic factors

can be considered.

Individual Response: EPA clarifies that all stimulation, in cluding hydraulic fracturing, must be approved by the Director based on site-specific information. Owners or operators must submit a proposed stimulation program as part of the permit application under §146.82(a)(9); the plan must demonstrate that any stimulation activit ies will not compromise the integrity of the confining zone. The Director will evaluate the owner or operator's proposed stimulation plan in

the context of all information a bout the site, and the owner or ope rator must perform stimulation only as approved.

The final rule at §146.91(d)(2) also requires that the owner or operator notify the Director 30 days before performing stimulation during the operational phase of a GS project; this will provide an additional opportunity for the Director to review the owner or operator's plans for stimulation and add other requirements as neede d. EPA clarifies that UIC regulations prohibit fracturing of the confining zone at any time during injection or stimulation.

Letter ID: 0241 Comment ID: 23244 Letter Lines: 288 to 296

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

Comment: 22. EPA seeks comment on the merits of requi ring down-hole shut-off valves in GS

17wells. EPA Notice 43511.

Requiring down-hole shut-off valves may be problematic. To protect the entire tubing-casing annulus they would need to be installed at or be low the injection packer. This may make the tool prone to failure. These valves may restrict or preclude the running of down hole monitori ng or logging tools. Inclusion of a seating nipple directly above the injection packer which would allow the

installation of a wire line set plug may be more appropriate.

Individual Response: After evaluating the risks and benefi ts of down-hole shut-off systems and considering additional research, EPA will not re quire 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 owne rs 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 believ es that offshore Class VI wells present unique construction and operational conditi ons, 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. Th e 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.

Landing nipples, which are machined portions of the tubing that allow the seating of components–such as safety valves—at a later time, can be used to deploy safety valves after the initial well completion. EPA believe s, however, that if the shut-off system is not deployed until the failure occurs, CO2 will be free to flow out of the well until the shut-off valve is deployed. Since installing the new shut-off system will requ ire getting the device to the site, setting up a rig, and deploying the device down the well, a si gnificant amount of time could elapse following

an adverse event before the well is sealed. EPA believes that the risks of uncontrolled CO2 flow are too great to be allowed for such a length of time.

Letter ID: 0241 Comment ID: 23245 Letter Lines: 298 to 315

Comment Code: 4324 2.4.4.1.2 Comments opposed to 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: 23. EPA is aware that the proposed requi rement of injecting CO2 below the lowermost USDW may preclude injection into certain targeted geologic formations, which may be storage sites currently under considerati on for GS. As a result, the Agency is considering and requesting comment on alternative approaches that would allow injection between and/or above the lowermost USDW, and thus potentially allow for more areas to be available for GS while preventing USDW endangerment. EPA Notice 43512.

18Injection into a formation above the lo wermost USDW should be allowed. As commented earlier, if injection above the lowermost USDW is not allowed it would eliminate a vast number of potential seque stration zones. Enhanced recovery operations above the lowermost USDW have been taking place for a very long time.

Exclusion of these zones where other abundant supplies of freshwater are available may severely limit sequestration options. These situa tions are best handled locally where other regional geologic factors can be considered. Demonstration that the upper and lower c onfining zones are adequate to prevent migration should be sufficient. The fact that the carbon dioxide plume is buoyant will protect any deeper USDW.

Individual Response: EPA acknowledges that there are lim ited circumstances where injection above the lowermost USDW can be performe d in a manner that protects USDWs from endangerment, as long as appropriate protections are in place. The final GS rule at §146.95 establishes a process by which owne rs or operators can seek a waiv er of the Class VI injection depth requirements for injecti on into non-USDW formations above and/or between USDWs. The

final rule also establishes limited circumstances under which expansions of the areal extent of aquifer exemptions may be granted for owne rs or operators of Class II EOR/EGR wells transitioning to Class VI injec tion for GS. Additionally, the final GS rule does not categorically preclude or prohibit in jection into any type of formation.

EPA believes that these requirements will ensure USDW protection while providing flexibility to UIC program Directors and owne rs or operators who undertak e CO2 injection for GS. The Agency believes this approach: 1) responds to co ncerns about local and re gional geologic storage capacity limitations imposed by th e proposed injection depth require ments; 2) allows for a more site-specific assessment of injection depth for GS projects; 3) accommodates injection into different formation types; 4) a llows for injection of CO2 for GS into non-USDWs above and/or between USDWs when appropriate and where it can be demonstrated that USDWs will be protected; and 5) responds to concerns about the use of aqui fer exemptions for GS. Finally, EPA’s approach to addressing injection depth va riability through a waiver process responds to concerns about future drinking wa ter resource availability and the need to ensure that high quality water remains available in sufficient qua ntities to supply drinking water needs. For additional information on the waiver approach For additional information on the waiver approach, please see the final rule and preamble, as well as EPA's responses to comments on the Notice of Data Availability and Request for Comme nt., please see the final rule and preamble, as well as EPA's responses to comments on the No tice of Data Availability and Request for

Comment.

Letter ID: 0241 Comment ID: 23246 Letter Lines: 317 to 332

Comment Code: 4324 2.4.4.1.2 Comments opposed to 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

19Comment: 24. 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., thous ands 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 43512.

Injection into a formation above the lo wermost USDW should be allowed. As commented earlier, if injection above the lowermost USDW is not allowed it would eliminate a vast number of potential seque stration zones. Enhanced recovery operations above the lowermost USDW have been taking place for a very long time.

Exclusion of these zones where other abundant supplies of freshwater are available may severely limit sequestration options. These situa tions are best handled locally where other regional geologic factors can be considered. Demonstration that the upper and lower c onfining zones are adequate to prevent migration should be sufficient. The fact that the carbon dioxide plume is buoyant will protect any deeper USDW.

Individual Response: As described above, EPA acknowledges that there are limited circumstances where injection above the lowerm ost USDW can be performed in a manner that protects USDWs from endangerment, as long as appropriate protections are in place. The final GS rule at §146.95 establishes a pr ocess by which owners or operato rs can seek a waiver of the Class VI injection depth requirements for inje ction into non-USDW form ations above and/or

between USDWs.

Letter ID: 0241 Comment ID: 23247 Letter Lines: 334 to 339

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

circumstances

Comment: 25. EPA is also requesting comments on whet her aquifer exemptions should be allowed for the purpose of Class VI inj ection, and under what conditions should such aquifer exemptions be approved. EPA Notice 43512.

Aquifer exemptions should be allowed pur suant to existing requirements in other injection well classes.

Individual Response: EPA acknowledges that there are lim ited circumstances where aquifer exemptions for GS may be warranted. The final rule allows for the expansion of the areal extent of existing aquifer exemptions for Class II EOR/ EGR wells transitioning to Class VI injection for GS pursuant to requirements at §§146.4 and 144.7( d). Class VI owners or operators granted expansions of existing Class II EOR/EGR aquifer exemptions for GS projects must meet all of the tailored requirements for GS wells in the final GS rule.

However, the final rule precludes the issuance of new aquifer exemptions for Class VI GS wells; that is, aquifer exemptions will only be granted for projects that are transitioning from Class II

EOR/EGR wells to Class VI.

20For additional information on aquifer exemptions for Class VI wells, please see the final rule and preamble, as well as EPA's responses to comments on the Notice of Da ta Availability and Request for Comment.

Letter ID: 0241 Comment ID: 23248 Letter Lines: 341 to 349

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

Comment: 26. EPA seeks comment on whether the Agency should set a minimum injection depth requirement for CO2 GS, rather than require that such injection take place below

the lowermost USDW. EPA Notice 43512.

There should not be a minimum injection de pth. The determining factor should be whether the project will be protective of USDWs. A minimum depth requirement suggests a requirement to inject carbon dioxide in a supercri tical phase. This is not appropriate since there may be pr ojects where injectio n of carbon dioxide in other phases is the most effective option.

Individual Response: EPA agrees that it is not appropriate to set a mi nimum injection depth for GS projects and the Agency believes that a determ ination of site-suitabili ty for GS (i.e., that

subsurface formations will receiv e and confine injected CO2) s hould be made on a site-specific basis. The GS rule, at §146.82, requires the owne r or operator to provide extensive site- and project-specific information to the Director to demonstrate that the site meets the minimum site criteria at §146.83, that the CO2 will be contai ned within the injection formation, and that USDWs will be protected from endangerment.

EPA acknowledges that there are limited circum stances where injectio n above the lowermost USDW can be performed in a manner that protec ts USDWs, as long as appropriate protections are in place. The final GS rule at §146.95 establis hes a process by which owners or operators can seek a waiver of the Class VI injection de pth requirements for in jection into non-USDW

formations above and/or between USDWs. The waiver approach requires the submission of extensive, site-specific information (in conjunc tion with the permit appl ication submission) to demonstrate that injection of CO2 into a non-US DW that is above or between USDWs can be done in a manner that is protective of USDWs. Th e requirements are designed to ensure that the owner or operator, the Director, and the Regional Administrator cons ider, on a site specific basis, the implications, benefits, and challenges associat ed with GS and ensuring water availability and USDW protection. For additional information on the waiver approach, please see the final rule and preamble, as well as EPA's responses to comments on the Notice of Data Availability and Request for Comment.

Letter ID: 0241 Comment ID: 23249 Letter Lines: 351 to 360

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

21(seeking comment)

Comment: 27. EPA’s proposal allows Directors’ discre tion on whether to require the use of tracers, and if so, what types of tr acers. EPA seeks comment on the use of tracers in CO2 GS operations and any poten tial impact of tracers on human health or ecosystems as they relate to USDWs. EPA Notice 43513.

Discretion on whether to use a tracer is appropriate. Radioactive tracers have been successfully utilized in oil and gas operations. The small amount used

should not threaten human health or USDW s. However, modeling and monitoring are generally more appropriate techniques to track a plume since tracers have a limited radius of investigation.

Individual Response: EPA believes that, in some circumst ances, tracers can be an important component of a multifaceted approach to mon itoring GS projects. However, the Agency recognizes that tracers may not be appropriate in all GS project s. For this reason, EPA does not require the use of tracers at all GS sites; however, the Director ha s discretion to require their use

if he/she determines that the use of tracers could improve mon itoring of the site and enhance USDW protection from endangerment.

While the intent of the GS regulations is to prevent leaks of CO2 to USDWs, EPA clarifies that all of the protective components of the regulation, includin g a comprehensive monitoring program per §146.90 (which includes testing of th e well, ground water quality monitoring, and tracking of the CO2 plume and pressure front) support a multi-barrier approach to protecting USDWs. Additionally, some studies (e.g., Phel ps and Cole, 2008; Hovorka et al., 2004; McCallum et al., 2005) found that tracers can pr ovide useful CO2 monitoring information at injection wells both at depth and at near-surface locations. At Fr io, tracers enabled quantification of CO2 plume behavior and provided a techniqu e for model validity tes ting (McCallum et al., 2005). EPA will continue to track research related to tracer use. The Agency plans to, every six years, collect and review data on GS projects to determine whether the appropriate amount and types of information and appropriate documenta tion are being collected, and to determine if modifications to the requirements are appropriate or necessary.

Letter ID: 0241 Comment ID: 23250 Letter Lines: 362 to 371

Comment Code: 4543 2.5.2.1 MIT procedures and methods for GS (seeking comment)

Comment: 28. EPA’s proposal would require owners or op erators of Class VI GS projects to monitor internal mechanical integrity of their injection wells by continuously monitoring injection pressure, flow rate, and injected volumes, as well as the annular pressure and fluid volume to assu re that no anomalies occur that may indicate an internal leak. EPA requests comment on the practicability of this requirement. EPA Notice 43513.

The monitoring of this data is approp riate. Continuous monitoring should be clarified as daily for most applications . This could be more stringent or

22frequent on a case-by-case basis.

Individual Response: EPA agrees with the commenter regarding the importance of demonstrating internal mechanical integrity (M I), and that continuous pressure monitoring of Class VI wells is appropriate. EPA disagrees with the suggest ed changes, however. Class VI injection wells will be equipped with dedicated computer-based continuo us pressure monitoring devices (in concert with the shut-off systems required for GS wells), which typically take readings several times per second (e.g., more frequently than da ily) and record them electronically in a computer system.

Continuous monitoring was found to be very importa nt in an EPA study of UIC Class I internal MIT failure rates and causes (USEPA 1993). Th e study reviewed MIT results over a 5 year period and found 135 MIT failures in 428 wells (a single well can have more than one MIT failure). In all cases, the MIT failures were found through continuous annulus monitoring which served the important role of an early warning to prevent any well failure. Class VI injection wells will be equipped with dedicated computer-based continuous pressure monitoring devices (in concert with the shut-off systems required for GS wells), which typically take readings several times per second and record them electronically in a computer system. §146.91(a)(2) requires that monthly averages of the continuous annul us monitoring be reporte d on a semiannual basis.

Letter ID: 0241 Comment ID: 23251 Letter Lines: 373 to 381

Comment Code: 4546 2.5.2.2 MIT frequency (seeking comment)

Comment: 29. EPA seeks comment on the appropriate fre quency of internal a nd external MITs for GS injection wells, the appropriate types of MITs, and how to optimize MIT

methods for GS. EPA Notice 43514.

A five-year frequency to conduct and review internal and external mechanical integrity is appropriate. A standard pressu re test utilizing a fluid compatible with the annular fluid is widely pr acticed but other me thods should be available. More frequent testing or review could be required based upon specific factors.

Individual Response: EPA disagrees that a five-year extern al MIT is appropriate. The final GS regulation retains the requirement that owners or operators of Class VI wells must demonstrate injection well external mech anical integrity at least once annually under §146.89(c). EPA believes this is justifiable for the protecti on of USDWs from endangerment given the unique nature of CO2 GS relative to other injection operations, including the pote ntial corrosive impact of CO2 in the presence of water and impurities on well materials, the potential geomechanical impacts to well integrity due to CO2 phase ch anges, the temperature and pressure effects associated with injecting supercritical CO2, and the buoyant nature of th e injected CO2. Because of the unknown long-term effects of CO2 GS, EPA chose a more cons ervative initial approach in the early stages of deployment for GS.

23In addition, a comprehensive review conducte d by EPA of MIT results from 1993 to 1998 found that Class I wells injecting corrosi ve fluids fail MITs at rates two to three times higher than those that inject non-corrosive fluids (USEPA 1999). Given the potentia l for CO2 to be corrosive (e.g., in the presence of water or aqueous formation flui ds), there is a potential risk factor for MIT

failure and, for this reason, EPA be lieves that the tailored MIT requi rements in the final GS rule are appropriate.

EPA clarifies that inte rnal MI must be demonstrated th rough continuous pressure monitoring under §146.89(b); EPA believes this is superior to an annual annulus pressure MIT, given the unique properties of CO2 injection for GS.

EPA adds that it is using an ad aptive approach to regulating GS. The Agency plans to collect and review data every six years on GS projects, including MIT da ta, to determine whether the appropriate amount and types of information a nd appropriate documentation are being collected,

and to determine if modifications to the requirements are appropriate or necessary.

Letter ID: 0241 Comment ID: 23252 Letter Lines: 383 to 390

Comment Code: 4650 2.6.5 CO2 plume and pressure fr ont tracking (seeking comment)

Comment: 30. EPA seeks comment on the requirement for monitoring of GS sites for the purpose of tracking the locati on of the CO2 plume and associated pressure front

over time. EPA Notice 43514.

Monitoring of the carbon dioxide plume is appropriate however caution is advised with respect to requiring monitoring wells since these may provide a conduit for unwanted migration. 4D seismic and predic tive models will improve over time due to iterative processes.

Individual Response: 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 believes, however, that monitoring using we lls in the injection zone, e.g., for pressure monitoring as required at §146.90(g)(1), can be safe ly performed if the we lls are constructed to prevent flow between the injection zone and US DWs or other layers a bove the confining zone. Such construction technologies ex ist and have been used in the oil and gas industry for years. EPA believes that properly constructed monitoring wells will be a safe way to obtain the data that is essential to ensure that the injected CO 2 remains confined in the injection zone and that pressure changes are not causing movement of formation or other fluids. EPA is developing guidance on well construction that will in clude recommendations for monitoring well construction. The guidance will be available on EPA’s website at http://water.epa.gov/type/groundwat er/uic/wells_se questration.cfm.

EPA is developing guidance on testing and mon itoring to assist owne rs or operators and

24Directors in evaluating requi rements under §146.90, including pr oposed monitoring plans. The guidance describes available technologies a nd recommended approaches for implementing a testing and monitoring plan, including pre-ope rational geophysical l ogging and testing of injection wells, MITs, injecti on well testing during operation, groundwater quality monitoring, tracking the CO2 plume and pressure front, a nd soil gas and surface air monitoring which may be required by the UIC Director for specific GS projects. Th e guidance can be found on EPA’s website at http://water.epa.gov/type/gr oundwater/uic/wells_se questration.cfm.

Letter ID: 0241 Comment ID: 23253 Letter Lines: 392 to 397

Comment Code: 4640 2.6.4 Pressure fall-off testing (seeking comment)

Comment: 31. EPA’s proposal would require that owne rs or operators perform a pressure fall-off test at least once every five y ears. EPA seeks comment on the use and frequency of pressure fall-off te sting for GS wells. EPA Notice 43515.

An initial pressure fall-off test coul d be required and subsequent tests required at the time the AOR is reevaluated.

Individual Response: EPA believes that a frequency of at least once every five years, as specified at §146.90(f), is an appropr iate interval for pressure fall- off testing (particularly given the suite of tests operators will perform on the well and the site). EPA adds that this frequency is the same as that required for AoR reevaluations . EPA clarifies that th e Director may require more frequent pressure fall-off tests at a specific project, if necessary based on site-specific circumstances. Pressure fall-off tests may be conducted in conjunc tion with other well performance tests (i.e., mechanical integrity testing) to ensure sa fe and effective operations. All monitoring data collected, including information from pressure fall-off tests, will be incorporated

in AoR reevaluations, at l east every five years.

Letter ID: 0241 Comment ID: 23254 Letter Lines: 399 to 407

Comment Code: 4650 2.6.5 CO2 plume and pressure fr ont tracking (seeking comment)

Comment: 32. Based on information evaluated to date , EPA believes that tracking the plume and pressure front is an important companion step to address any uncertainties associated with initial AoR modeling and requests comment on this approach and more efficient alternatives that may be used to track the plume and pressure

front. EPA Notice 43516.

Tracking the plume and pressure front will allow for verification of the

reservoir model. Pressure transient te sting and seismic techniques may be

useful alternatives.

Individual Response: The final rule (at §146.90(g)) requires owners or operators to perform monitoring to track the extent of the CO2 plume and pressure fr ont. The owner or operator must

25use direct methods to monitor for pressure chan ges in the injection zone. Indirect methods (e.g., seismic, electrical, gravity, or electromagnetic surveys and/or down-hol e CO2 detection tools) are also required unless the Di rector determines, based on s ite-specific geology, that such methods are not appropriate. EPA is affording Director's discretion regarding the use of geophysical techniques at some sites because the Agency recognizes that geophysical methods are not appropriate in all geologi c settings. EPA clarifies that th is determination will be made by the Director based on the site-specific geologi c information submitted by the owner or operator with their permit application.

EPA believes that this approach provides flexibility to develop a site-specific monitoring plan, ensures that direct monitoring is available to track the movement of the CO2 and validate models, and recognizes that indirect techniques are not appropriate in all situations. The owner or operator's approved testing and monitoring pl an will include the site-specific details, technologies, testing and monitoring freque ncies, and other pertinent information.

Letter ID: 0241 Comment ID: 23255 Letter Lines: 409 to 417

Comment Code: 4670 2.6.7 Surface air monitoring and/or soil gas monitoring (seeking comment)

Comment: 33. EPA seeks comment on the appropriate am ount and types of monitoring that should be conducted at a GS site. Specifi cally, EPA seeks comment regarding the usefulness of indirect geophysical monitoring and surface air and soil gas monitoring. In addition, EPA seeks commen t regarding the use of a Directorapproved monitoring plan for GS sites. EPA Notice 43517.

Monitoring techniques should be determined on a site-specific basis and be based upon potential risks posed by the project and the cost versus benefit of monitoring.

Individual Response: EPA agrees that monitoring plans and methods need to be site-specific and believes that the monitoring requirements for GS sites at §146.90 provide an appropriate level of flexibility in structuring a testing and monitoring plan that protects USDWs from endangerment. The final regulation provides for fl exibility in: 1) methodol ogies used to collect these data, 2) the spatial resolution at which the data should be collected, and 3) how often thedata should be collected. The number and placement of monitoring wells will be based on sitespecific information such as the calculated AoR, injection rate and volume, site geology, baseline data, and the presence of artificial penetrations within the AoR. EPA believes that this is the best approach for addressing potenti al risks at GS sites.

EPA recognizes that installation of monitoring wells entails additional resources. However, the Agency believes that such monitoring is necessary to ensure that GS projects are appropriately operated and monitored and to pr otect USDWs from endangerment.

Although a significant cost in abso lute terms, monitoring costs are expected to be a small fraction of site operating costs, according to EPA' s cost analysis for the GS rulemaking (which is

26available in the docket). While the rule requir ements will necessitate additional costs, the requirements are guided by the necessity to address the unique challenges posed by CO2 injection (including large injection volumes, the relative buoyancy of CO2, its corrosivity in the presence of water, the potential presence of impu rities in captured CO2, and its mobility within subsurface geologic formations) as they protect USDWs from endangerment.

The UIC requirements are designed to ensure that where GS is employed, it is done in a manner that protects USDWs from endangerment, cons istent with the UIC Program's authority under

SDWA.

EPA is developing guidance on testing and mon itoring to assist owne rs or operators and Directors in evaluating requi rements under §146.90, including pr oposed monitoring plans. The guidance describes available technologies a nd recommended approaches for implementing a testing and monitoring plan, including pre-ope rational geophysical l ogging and testing of injection wells, MITs, injecti on well testing during operation, groundwater quality monitoring, tracking the CO2 plume and pre ssure front, and soil gas and su rface air monitoring which may be required by the UIC Director for specific GS projects. Th e guidance can be found on EPA’s website at http://water.epa.gov/type/gr oundwater/uic/wells_se questration.cfm.

Letter ID: 0241 Comment ID: 23256 Letter Lines: 419 to 432

Comment Code: 4610 2.6.1 Testing and monitoring plan requirement (seeking comment)

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

Comment: 34. EPA is proposing that permit applications for GS sites include several plans not currently required under existing UI C regulations. These plans include a monitoring and testing plan, an AoR a nd corrective action plan, and a postinjection site care and site closure pla n. EPA seeks comment on the merits of requiring plans for monitoring, AoR, and post- injection site care as part of a permit application. EPA Notice 43517.

Allowing for different plans would be mu ch more effective than prescriptive regulations; however, a plan modification should not be considered a major permit modification. Caution needs to be taken when monitoring the injection formation due to the artificial penetration of the confining zone to gain data. The number of monitoring wells should be decided on a case-by case basis. It is unclear how monitoring wells will be re gulated since they are not injection wells. The timing of plan submittal should be linked to the activity being

Individual Response: EPA agrees with commenters that developing and following testing and monitoring plans is an important pa rt of assuring that a GS projec t is operating properly and is crucial for the early detection of potential endangerment to USDWs.

EPA expects that the number of monitoring well s needed will be determined based on site27specific information as the testing and monito ring plan is developed. EPA believes that monitoring using wells in the injec tion zone (i.e., that penetrate th e confining zone) can be safely performed if the wells are constructed to preven t flow between the injec tion zone and USDWs or other layers above the confining zone. Such construction technologi es exist and have been used in the oil and gas industry for year s. EPA believes that the benefits of monitoring in the injection formation outweigh the manageable risk of thos e monitoring wells serving as conduits for fluid

movement.

EPA also agrees that periodic updates to the plan are appropriate. EPA clarif ies that the final GS regulation includes a requirement that the AoR be reevaluated at least every 5 years, and it specifies at §146.90(j) that the oper ator revise the testing and mon itoring plan to incorporate the

results of the most recent AoR reevaluation and recent operational and monitoring data. EPA clarifies that every revision to the testing and m onitoring plan will not necessarily trigger a major permit modification. The existing regulation at 40 CFR 144.39(a) identifies causes for modification of permits that would invoke the public notification procedures at 40 CFR 124, including: alterations or additions to the facility; availabi lity of additional information; new regulations; and compliance schedule modificati ons. In the final rule, EPA added text to §144.39(a)(5) that permit modifications would be re quired if the Director determines that a modification is necessary based on an AoR reevalua tion, amendments to any of the project plans,

or a review of the testin g and monitoring results.

In addition, 40 CFR Part 144.41 identifies causes fo r minor modifications of permits (which do not require following the proce dures of Part 124). These incl ude correction of typographical errors; more frequent monitoring or reporting; changes in an inte rim compliance date; changes in ownership or control of a facility ; changes in the quantities or type s of fluids injected which are within the capacity of the fac ility; changes in construction requirements; or amendments to a plugging and abandonment plan. In the final rule , EPA added a subparagraph (h) to §144.41 that would include minor amendments (e.g., to clarify, correct, or update) the testing and monitoring plan, plugging plan, post-in jection site care and site closur e plan, or emergency and remedial response plan for a GS well (i.e., amendments that are not included under 144.39(a)(5) and that do not require additional permit requirements).

EPA is developing guidance on testing and mon itoring to assist owne rs or operators and Directors in evaluating requi rements under §146.90, including pr oposed monitoring plans. The guidance describes available technologies a nd recommended approaches for implementing a testing and monitoring plan, including pre-ope rational geophysical l ogging and testing of injection wells, MITs, injecti on well testing during operation, groundwater quality monitoring, tracking the CO2 plume and pressure front, a nd soil gas and surface air monitoring which may be required by the UIC Director for specific GS projects. Th e guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/u ic/wells_sequestration.cfm. In addition, in January 2009, DOE published a best practices ma nual entitled "Monitoring, Verification, and Accounting of CO2 Stored in Deep Geol ogic Formations" (DOE /NETL-311/081508); this

manual is included in the docket for the final GS rule. EPA notes that closure of monitoring wells should be addressed in the post-inj ection site care and site closure plan.

28Letter ID: 0241 Comment ID: 23257 Letter Lines: 432 to 435

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

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

Comment: wells. The timing of plan submittal should be linked to the activity being addressed. Site closure plans, post-clos ure plans, well plugging plans, etc., should not be required many years in adva nce since conditions, understanding of the sequestration zones, and t echnology change over time.

Individual Response: EPA disagrees with the commenter's assertion that that the timing of plan submittals should be linked to the specific activity being addressed, and believes that submittal and review of each of the owner or operator's plans required at §146.82 at the time of the permit application is necessary for the Director to make a permit approval determination. While injection well plugging, pos t-injection site care a nd site closure will lik ely not occur for years after injection commences, the Director needs to have assurance that the owner or operator has planned for these events.

Letter ID: 0241 Comment ID: 23258 Letter Lines: 437 to 441

Comment Code: 4760 2.7.6 Proposed reporting frequency (seeking comment)

Comment: 35. EPA seeks comment on the frequency of all proposed reporting requirements.

EPA Notice 43517.

Reporting frequency should coincide with re quirements for existing UIC injection

well classes unless there is a need for more frequent reporting.

Individual Response: EPA clarifies that reporting requirements for existing injection wells vary by well class. The Agency believes semi-annual re porting is appropriate for Class VI GS wells during the operational phase of the project. EPA believes that the potentially large injection volumes and injection pressures associated with GS warrant mo re frequent reporting than for

other well classes. See the fina l rule and preamble for further di scussion on EPA's final approach to reporting and recordkeeping.

EPA is using an adaptive approach to regula ting GS. The Agency plan s to, every six years, collect and review data on GS projects to dete rmine 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: 0241 Comment ID: 23259 Letter Lines: 443 to 448

Comment Code: 4740 2.7.4 Electronic reporting (seeking comment)

29Comment: 36. EPA seeks comment on the requiremen t for electronic reporting in its proposed rule. EPA Notice 43518.

Electronic reporting should not be required. State systems may already be in place to collect data but may not be co mpatible with sending or receiving

systems.

Individual Response: EPA believes that electronic formatting is the most appropriate format for submitting Class VI project information to the Director, and based on comments received on the proposed rule, the majority of Class VI well owners or operators will have the capability to report electronically, and re quires this at §146.91(e).

Acknowledging that some States may have to develop electronic data systems to receive

electronic information from the owner or operator, and that many States which already have electronic data systems will have to make ch anges to accommodate a new class of UIC well (Class VI), EPA believes that it is prudent to provide assi stance by develo ping a central framework for the electronic system that will be used by States to gather and track owner or operator data. This will enable owners or opera tors to submit data without having to wait for a State to develop a system. It will also provide for standardized submissions across the country

and enable States to focus State resources on re viewing and approving permit applications rather than building or upgrading separate, inde pendent databases for GS information.

EPA is developing guidance for states that describes the recordkeeping, reporting, and additional data management needs associated with GS act ivities and provides recommended guidelines on the types of data to be collected for tracki ng GS projects, reporti ng to EPA for compliance tracking, and transfer of data to EPA's GS data system. The recordkeeping and reporting guidance will be available on EPA's web site, at http://water.epa.gov/type/groundwater /uic/wells_sequestration.cfm.

Letter ID: 0241 Comment ID: 23260 Letter Lines: 450 to 459

Comment Code: 4750 2.7.5 Comments on the merit of a nnual reports (seeking comment)

Comment: 37. In addition to the above recordkeeping and reporting requirements, EPA considered a requirement for owners or operators of GS sites to provide an annual report during the lifetime of the project, including the post-injection period, regarding the GS operation. Although EPA has not included a requirement for this report in its proposal, EPA s eeks comment regarding the necessity for such an annual report. EPA Notice 43518.

During the active injection phase of a proj ect, reports and frequencies similar

to those which exist in other UIC cla sses should be sufficient. Once active injection ceases, an annual report may be appropriate.

Individual Response: EPA clarifies that reporting requirements for existing injection wells vary by well class. The Agency believes semi-annual re porting is appropriate for Class VI GS wells

30during the operational phase of the project. EPA believes that the potentially large injection volumes and injection pressures associated with GS warrant mo re frequent reporting than for other well classes. EPA adds, at §146.93(a)(2)(iv), that reporting during the post-injection site

care timeframe would be at the fr equency described in the approve d post-injection site care and site closure plan. For additional information, plea se see the final rule and the preamble for a discussion of EPA's final approach to recordkeeping and reporting.

Letter ID: 0241 Comment ID: 23261 Letter Lines: 461 to 469

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

Comment Code: 5260 2.8.2.3 Adjusting the post-injecti on timeframe (seeking comment)

Comment: 38. EPA is proposing using a combination of fixed timeframe a nd a performance

standard as described above . EPA is tentatively proposi ng a post-injection site care (monitoring) period of 50 years with Di rector’s discretion to change that period to lengthen or shorten the 50-y ear period if appropriate. EPA requests comment on the proposed use of a tentative 50-year fixed timefram e that could be

modified at the Director’s discretion based on monitori ng and modeling data. EPA

Notice 43519.

A performance-based time period is appropr iate rather than a fixed timeframe.

Individual Response: EPA agrees that there will be circumst ances where it can be demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of endangerment to

USDWs. For this reason, the GS ru le offers owners or operators flexibility regard ing the duration of the PISC timeframe by: (1) allowing the Direct or discretion to shorten or lengthen the PISC timeframe during the post-injecti on period based on site-specific da ta, 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 ensu res non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from enda ngerment, a default timeframe for post-injection site care will be necessary in al l but a limited number of cases. This default 50 year post-injection site care ti meframe represents a reasonable and protective monitoring period

based on a review of research studies, industr y reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site car e 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 ac commodate site-specific circumstances and various geologic conditions, and addre sses commenters’ concerns, wh ile ensuring USDW protection. Both approaches will utilize si te-specific data, and be based on pressure monitoring and USDW impacts.

31Letter ID: 0241 Comment ID: 23262 Letter Lines: 471 to 475

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

Comment Code: 5260 2.8.2.3 Adjusting the post-injecti on timeframe (seeking comment)

Comment: 39. EPA is requesting comments on the pr oposed requirements for well plugging, post-injection site care, a nd site closure, including the proposed requirements for the post-injection time period. EPA Notice 43520.

A performance-based time period is appropr iate rather than a fixed timeframe.

Individual Response: EPA agrees that there will be circumst ances where it can be demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of endangerment to

USDWs. For this reason, the GS ru le offers owners or operators flexibility regard ing the duration of the PISC timeframe by: (1) allowing the Direct or discretion to shorten or lengthen the PISC timeframe during the post-injecti on period based on site-specific da ta, 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 ensu res non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from enda ngerment, a default timeframe for post-injection site care will be necessary in al l but a limited number of cases. This default 50 year post-injection site care ti meframe represents a reasonable and protective monitoring period

based on a review of research studies, industr y reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site car e 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 ac commodate site-specific circumstances and various geologic conditions, and addre sses commenters’ concerns, wh ile ensuring USDW protection. Both approaches will utilize si te-specific data, and be based on pressure monitoring and USDW impacts.

Letter ID: 0241 Comment ID: 23263 Letter Lines: 477 to 482

Comment Code: 5260 2.8.2.3 Adjusting the post-injecti on timeframe (seeking comment)

Comment: 40. In addition, EPA seeks comment on whethe r the Director should be allowed to shorten the timeframe based on performan ce information, and whether EPA should require a shorter or longer post injec tion period if data suggests the time frame should be adjusted. EPA Notice 43520.

32A performance-based time period is appropr iate rather than a fixed timeframe.

Individual Response: The PISC requirements in the final GS rule, as specified in §146.93(b), incorporate a combination of a fixed timeframe and a performance standard approach. EPA believes that a default PISC timeframe of 50 year s, with Director's di scretion to shorten or lengthen this timeframe, combined with a site-s pecific Director’s disc retion to create an

alternative PISC time frame, ensu res that USDWs are protected. The GS rule offers owners or operators flexibility regarding th e duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengt hen the PISC timeframe during the PISC period based on sitespecific data, pursuant to require ments at §146.93(b); or (2) afford ing the Director discretion to allow a Class VI well owner or operator to demo nstrate, based on substa ntial data during the permitting process, that an alternative PISC timeframe may be appropriate if it ensures nonendangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from enda ngerment, a default timeframe for post-injection site care will be necessary in most cases. The default 50 year post-injection site care timeframe represents a reasonable and prot ective monitoring period based on a review of research studies, industry reports, and existing environmental programs, and evaluation of public

comments.

EPA believes that a default post-injection site car e 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 ac commodate site-specific circumstances and various geologic conditions, and addre sses commenters’ concerns, wh ile ensuring USDW protection. Both approaches will utilize si te-specific data, and be based on pressure monitoring and USDW impacts.

Letter ID: 0241 Comment ID: 23264 Letter Lines: 484 to 494

Comment Code: 5430 2.9.1 Comments on proposed financia l responsibility requirements (40 CFR 146.85)

Comment: 41. Current UIC guidance describes trust funds as a form of financial assurance. The owner or operator may deposit funds in to the trust fund in phases; that is, either over the term of the initial permit or over the remaining operating life of the injection well, as estimated in the well plugging plan, whichever period is shorter. Because of the possibility that the owner or operator may face financial distress prior to the trust be ing fully funded, EPA is considering a guidance approach that woul d recommend adopting a pay in period of three years for GS projects, consistent with other similar programs in the Agency. EPA

Notice 43521.

The pay-in period should coincide with the estimated risk.

33Individual Response: EPA acknowledges that there may be several possible approaches to setting pay-in periods for trust funds. The final rule requires that the Di rector approve the use and length of pay-in periods. EPA is devel oping guidance (available on EPA's website at http://water.epa.gov/type/groundwat er/uic/wells_sequest ration.cfm) that describes the types of financial instruments that owners or operato rs can use to meet financial responsibility requirements for GS wells. Specifically, the guida nce will discuss pay-in periods and provide guidance for Directors to use in determining an appropriate pay-in period. EPA adds that owners or operators may choose from a variety of fi nancial instruments to meet their financial responsibility obligations. See th e final rule and preamble for fu rther discussion of EPA's final approach to financial responsibility.

Letter ID: 0241 Comment ID: 23265 Letter Lines: 496 to 506

Comment Code: 5430 2.9.1 Comments on proposed financia l responsibility requirements (40 CFR 146.85)

Comment: 42. Current UIC regulations for Class I h azardous waste injec tion allow for the use of insurance for purposes of dem onstrating financia l responsibility. However, insurance was not included as pa rt of the guidance provided for Class II injection because this in surance mechanism was and still is, rarely used for the purpose of demonstrating financial a ssurance for injection wells. EPA is assessing whether to provide guidance on th e use of insurance providers and, if so, whether to update eligibility requir ements for insurers for GS wells

consistent with other current Federa l agency practices. EPA Notice 43521.

Financial assurance should be left to st ate lawmakers and the regulating agency and should not be a prescribed mechanism.

Individual Response: Regarding the suggestion that financia l assurance requirements be left to the states, EPA notes that it is providing consis tency nationwide by requiri ng that any state that wishes to assume primacy for Class VI wells would need to demonstrate that its financial responsibility requirements are at least as stri ngent as the minimum federal requirements at §146.85. EPA does not believe that the final rule is pr escriptive; rather it is flexible in order to tailor the regulations to the unique charac teristics of long term storage of CO2.

EPA agrees that it is appropriate to allow a flexible approach for financial res ponsibility. Under the final GS rule owners or operators may choose from a variety of financial instruments to meet their financial responsibility obligations, provide d the Director determines that the owner or operator's proposed financial responsibility dem onstration is adequate to prevent endangerment of USDWs by demonstrating the ability to pay fo r each activity for which financial responsibility

must be demonstrated, includi ng corrective action on wells in the AoR, injection well plugging, PISC and site closure, and emergency and remedi al response. See the final rule and preamble for further discussion of EPA's final appr oach to financial responsibility.

34Letter ID: 0241 Comment ID: 23266 Letter Lines: 508 to 516

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

Comment: 43. EPA is assessing whether a financial ratings threshold for all companies using a self-guarantee, similar to thos e used by other Federal agencies, is appropriate. The Agency also is consider ing what constitute s an appropriate financial rating threshold, and whether a financial rating greater than BBB or Baa (i.e., the current rating threshold established under the UIC regulations) is appropriate for GS wells. EPA Notice 43522.

Financial assurance should be left to st ate lawmakers and the regulating agency and should not be a prescribed mechanism.

Individual Response: EPA disagrees that the GS rule is over ly prescriptive; rather it offers anadaptive and flexible approach that will be best for purposes of addressing the variety of sitespecific circumstances to be encountered in GS projects. Furthermore, EPA notes that it is providing consistency nationwide by requiring that any state that wi shes to assume primacy for Class VI wells demonstrate that its financial resp onsibility requirements are at least as stringent

as the minimum federa l requirements at §146.85.

EPA agrees that it is appropriate to allow a flexible approach for financial responsibility. Owners or operators may choose from a variety of fi nancial instruments to meet their financial responsibility obligations under the rule, provided the Director de termines that the operator's proposed financial responsibility demonstrat ion is adequate to protect USDWs from endangerment, which means the ability of the owner or operator to pay for each activity for which financial responsibility must be demonstr ated, including correctiv e action on wells in the AoR, injection well plugging, PISC and site cl osure, and emergency and remedial response throughout the life of the project. The final GS rule specifies at §146.85(a)(1) the permitted types of financial responsibility instru ments. See the final rule and pr eamble for further discussion of EPA's final approach to financial responsibility.

Additionally, EPA is developing guidance to help owners or operators, permitting authorities, and third parties choose and eval uate appropriate financial met hods and states may set more specific financial responsibility requirements if they so choose. This guidance will be available on EPA's website at http://water.epa.gov/type /groundwater/uic/wells_sequestration.cfm.

Letter ID: 0241 Comment ID: 23267 Letter Lines: 518 to 525

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

Comment: 44. EPA is requesting comments on whether fina ncial responsibility mechanisms to be recommended in EPA guidance should be adjusted in the manner described, whether additional instruments should be included, and whether other adjustments

35to the financial responsibili ty mechanisms should be considered, all subject to EPA’s authority under the SDWA. EPA Notice 43522.

Financial assurance should be left to st ate lawmakers and the regulating agency and should not be a prescribed mechanism.

Individual Response: EPA agrees that it is appropriate to al low a flexible approach for financial responsibility; however, EPA belie ves that a minimum framework fo r financial responsibility is necessary. Under the final GS rule owners or operators have the flexibility to choose from a variety of financial instruments to meet their financial responsibility obligations. Owners or operators may use one or multiple financial responsibility instruments for well plugging and PISC (§146.85(a)(6)). A demonstration of financial re sponsibility for all phases of the GS project will be required prior to the issuance of a Class VI permit (§146.85(a)(5)(i)).

EPA is developing guidance (a vailable on EPA's website at http://water.epa.gov/type/groundwater /uic/wells_sequestra tion.cfm) to help owners or operators, permitting authorities, and third parties choose and evaluate appr opriate financial methods, and states may set more specific financial respons ibility requirements if they so choose.

Letter ID: 0241 Comment ID: 23268 Letter Lines: 527 to 532

Comment Code: 5436 2.9.1.3 Allowing separate financial demonstrations for plugging and abandonment and post-injection si te care (seeking comment)

Comment: 45. The Agency is also requesting comme nt on allowing separate financial

demonstrations to be submitted for the plugging of the injection well and for the post-injection site care requirements. EPA Notice 43522.

This seems a sensible approach however; financial assurance should be left to the regulating agency and not prescribed.

Individual Response: EPA will allow owners or operators to use separate financial responsibility instruments for well plugging and site closure. Howeve r, owners or operators must demonstrate adequate financial responsibility for all required activities with their permit applications, per §146.82(a)(14), and financial respons ibility will need to be reevaluated prior to well plugging or site closure, or at any othe r time deemed appropriate by the Director. EPA believes this is necessary to ensure that resour ces are available to prevent the endangerment of USDWs in the event that the owner or operator experiences financial difficulties at any time during the life of the GS project.

Regarding the suggestion that financial assurance requirements be left to the states, EPA notes that it is providing consistenc y nationwide by requiring that any state that wishes to assume primacy for Class VI wells would need to de monstrate that its fi nancial responsibility requirements are at least as stringent as the minimum federa l requirements at §146.85. EPA does not believe that the final rule is pr escriptive; rather it is flexible in order to tailor the regulations to the unique characteristics of long term storage of CO2.

36Letter ID: 0241 Comment ID: 23269 Letter Lines: 534 to 542

Comment Code: 5520 2.10.1 Appropriateness of existing p ublic participation requirements (Part 25 and Part 124) for GS (seeking comment)

Comment: 46. EPA requests comment on adopting the existing requirements for public participation at 40 CFR Part 25 and 40 CFR Part 124 and whet her additional requirements should be included to reflect the availability of new tools for disseminating and gathering information. Su ch tools include cable networks, the Internet, and other new technology. EPA Notice 43523.

Public participation requirements should be left to the regu lating agency and not prescribed. Requirements could mirro r the agency’s existing public notice and participation requirements.

Individual Response: EPA agrees that the existing UIC public participation requirements as specified in 40 CFR 25 and 40 CFR 124 are appropria te for GS projects. In addition, because of the unique nature of GS projects, and the anticipa ted level of public intere st in GS projects, EPA encourages (but does not require) early public in volvement in GS projects. Providing the public with accurate, project specific information in the ear ly stages of each GS pr oject can help clarify project details and avoid public misperceptions about the nature and safety of GS projects, and will allow a potential GS owner or operator a nd the permitting agency to address the public's concerns before the permitting process is complete.

EPA is not requiring the use of new information technologies. EPA encourages GS operators to use new information technologies whenever possible to keep the public informed of GS projects. The Agency believes that flexibility is importa nt and does not want to limit use of public participation and notification tec hnologies developed in the future.

Letter ID: 0241 Comment ID: 23270 Letter Lines: 544 to 552

Comment Code: 5560 2.10.3 Enhancing the public particip ation process (seeking comment)

Comment: 47. EPA also requests comment on ways to enhance the public participation process, including engaging communities in the site characteri zation process as

soon as candidate locations ar e identified. EPA Notice 43523.

Public participation requirements should be left to the regu lating agency and not prescribed. The applicant shoul d be allowed to do some site characterization to assess site suitability and project feasibility before the public is engaged. Requirements could mirror the agency’s existing public notice and participation requirements.

Individual Response: EPA believes that the existing UIC p ublic participation requirements as

37specified in 40 CFR 25 and 40 CFR 124 are ap propriate for GS projects. GS permitting authorities must follow the existing public part icipation requirements for UIC permits as specified in 40 CFR Part 124. Thes e regulations lay out the proc edures for decision making and include requirements such as requiring the Direct or to notify the public re garding the availability of the draft permit and allow him or her to require a public hearing on the draft permit.

In addition, because of the unique nature of GS projects, and the anticipated level of public interest in GS projects, EPA encourages early pu blic involvement in GS projects. Providing the public with accurate, project specifi c information in the early stages of each GS project can help clarify project details and avoid public misper ceptions about the nature and safety of GS projects, and will allow a potential GS owner or operator and the permitting agency to address the public's concerns before the permitting process is complete.

Letter ID: 0241 Comment ID: 23271 Letter Lines: 554 to 563

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

Comment: 48. To gain authority for Class VI wells , States, Territories, and Tribes will be required to show that their regulations are at least as stringent as, and may be more stringent than, the proposed minimum Federal requirements (e.g., inspection, operation, monitoring, and reco rdkeeping requirements that well owners or operators must meet). Such Pr imacy States, Territories, and Tribes

are authorized under Section 1422 of the SDWA. EPA Notice 43523.

Partial primacy should be granted for Cla ss VI wells independently of other well classes and through a process similar to granting primacy under existing UIC classes, allowing the states to determ ine the appropriate regulating agency.

Individual Response: As described above, EPA agrees that states should be allowed to obtain primacy for Class VI wells independently of other well classes, and will allow independent primacy for Class VI wells under §1 45.1(i) of the final GS rule.

Letter ID: 0241 Comment ID: 23272 Letter Lines: 565 to 576

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

Comment: 49. There may be benefits to parsing out primacy for Class VI wells, however EPA has not made a decision on this. Allowing States, Territories, and Tribes to acquire primacy for only Class VI wells may encourage them to assume the responsibility of implementation and provide for a more comprehensive approach to managing CCS projects (e.g., captur e, transportation, and geologic sequestration). EPA is seeking comment on the merits and possible disadvantages of allowing primacy approval for Class VI wells independent of other well

classes. EPA Notice 43523.

38Partial primacy should be granted for Cla ss VI wells independently of other well classes allowing the states to determin e the appropriate re gulating agency. This will encourage states to apply for primacy.

Individual Response: As described above, EPA agrees that states should be allowed to obtain primacy for Class VI wells independently of other well classes, and will allow independent primacy for Class VI wells under §1 45.1(i) of the final GS rule.

Letter ID: 0241 Comment ID: 23273 Letter Lines: 578 to 583

Comment Code: 5700 2.12 Comments on the proposed durati on of Class VI permits (seeking comment)

Comment: 50. EPA proposes that Class VI injection we ll permits would be issued for the operating life of the GS project includi ng the post-injection si te care period. EPA seeks comment on the merits of this approach. EPA Notice 43523.

This will reduce administrative burde ns that would yield little or no

environmental benefit.

Individual Response: The final rule maintains the lifetime permit provision and clarifies that the permit extends through the post-injection site car e period (144.36(a)). However, it also adds a requirement that the Director review each Class VI permit at least once every 5 years to

determine whether it should be modified, re voked and reissued, terminated or a minor modification made as provided in §§144.39, 144.40, or 144.41. The Director’s review will be informed by the owners’ or operato rs’ iterative reev aluation of the project. Specifically, the final rule includes a requirement that the AoR be reev aluated at least every five years, and also requires owners or operators to review and update the AoR and corrective action plan, the testing and monitoring plan, and the emergency and reme dial response plan th roughout the life of the project (146.84(e), 146.90(j), and 146.94(d)). Owners or operators must review each plan and identify necessary amendments or demonstrate to the Director that no amendment is needed. In

no case can reviews occur less often than once ev ery five years. The iterative process and subsequent plan reevaluations ensure that time and resources are committed to the most critical aspects of the permit in preven ting endangerment to USDWs.

Letter ID: 0241 Comment ID: 23274 Letter Lines: 585 to 594

Comment Code: 6220 3.2.2 Assumptions about the number of monitoring wells (seeking comment)

Comment: 51. The Agency assumes three monitoring we lls per injection well for the purpose of estimating national costs; however, the Agency recognizes th at operators and primacy agency Directors may choose more or fewer monitoring wells depending on project site characteristics. Because th e monitoring wells and associated costs

39represent a significant component of the Cost Analys is, the Agency acknowledges that this factor may be significant in the overall uncertainty of the Cost Analysis. EPA requests comment on whether three monitoring wells per injection well is an appropriate costi ng assumption. EPA Notice 43527.

The number of monitoring wells requir ed will be very site specific.

Individual Response: EPA agrees that the number of mon itoring wells associated with GS projects will be site-specific and vary based on many factors, including the local geologic characteristics, the presence of other injection wells, the size of the AoR, and volumes of CO2 injected. The proposed rule Cost Analysis descri bed the number of monitori ng wells as a ratio to the number of injection wells; EPA clarifies that the number of injection wells was based on the size of the AoR and the type of project. Therefor e, the number of monitori ng wells was indirectly based on the size of the AoR. Because ER projec t sites have injection wells that are more

clustered than those in saline formations, the AoR and the number of monitoring wells were anticipated to be smaller at an ER project si te compared to a saline formation project. EPA retained this assumption regarding the density of injection wells fo r the final rule analysis, but it changed its assumption on the number of monitori ng wells at each site. For the final rule, the Agency assumes one monitoring well above the inj ection zone per two square miles of AoR; for monitoring wells into the injection zone, the Agency assumes one monitoring well per four square miles. EPA assumes monitoring wells into th e injection zone will also be used to sample above the injection zone. The number of monitoring wells assumed for each project type is presented in Exhibit 5.2 of the Cost Analysis.

Because the actual number of monitoring wells that will be necessary for a given project site is

uncertain, EPA tested the sensitiv ity of overall cost estimates to the number of monitoring wells by applying a 25 percent decrease and increase in monitoring wells per project type to the original assumptions. This change results in a nnualized incremental rule costs approximately 16 percent less and 16 percent greate r than costs estimated for the primary analysis (as shown in Exhibit 5.26 of the Cost Analysis). For addi tional information on EPA's final regulatory approach, including testing and monitoring requireme nts, please see the final rule and preamble.

EPA is developing guidance on monitoring and te sting to assist owne rs or operators and Directors in evaluating requi rements under §146.90, including de veloping determining the appropriate number of monitori ng wells for a GS site. This gui dance will be available on EPA’s website at http://water.epa.gov/type/gr oundwater/uic/wells_se questration.cfm.

Letter ID: 0241 Comment ID: 23275 Letter Lines: 596 to 603

Comment Code: 7700 4.7 Executive Order 13045: Child ren's Health Protection

Comment: 52. The public is invited to submit comment s or identify peer-reviewed studies

and data that assess the e ffects of early life exposure to changes in drinking water quality that may be caused by geol ogic sequestration of carbon dioxide.

EPA Notice 43531.

40There are no known unique characteristics of carbon dioxide in jection or its potential impacts on USDWs that have not been addressed within existing UIC

rules or found in current carbon dioxide injection projects.

Individual Response: EPA is funding research related to the potential for USDW contamination associated with GS projects. In addition, the Agen cy is tracking external research that focuses on potential exceedances of drinking water standards, which were developed by EPA and take into account impacts on children's health.

In the August 31, 2009, Notice of Data Availabi lity (NODA) and Request for Comment (74 FR 44802), EPA published the results of a study in which Lawrence Berkeley National Laboratory (LBNL) evaluated the potential for GS to cause changes in ground water quality as a result of CO2 leakage and subsequent mobilization of trace elements such as arsenic, barium, cadmium, mercury, lead, antimony, selenium, zinc, and uranium (Birkholzer et al., 2008a). LBNL

estimated the amount of trace elements from na tive mineral species that could potentially be mobilized by the intrusion of CO 2 and the potential ground water con centrations that could result to determine the potential for drinking water standards to be exceeded. EPA has also examined potential methods for conducting treatment of wa ter affected by a CO2 leak; this study is presented in the final rulemaking docket.

EPA continues to fund research in this area. In December 2009, EPA's Office of Research and Development (ORD) awarded a Science to Achieve Results (STAR) grant to Clemson University to investigate the potential for GS to affect USDWs. This research will involve laboratory experiments and modeling simulations to invest igate the fate of dissolved CO2 in underground geologic formations and to determine possible ri sks associated with the dissolution of CO2 in underground aquifers. This STAR Grant is among six such grants awarded to major universities and institutions focusing on: "Integrated De sign, Modeling and Monitoring of Geologic Sequestration of Anthropogenic Carbon Dioxide to Safeguard Sources of Drinking Water."

EPA clarifies that the purpose of the GS rule is to protec t USDWs from endangerment through permitting, siting, construction, operation, injection, a nd post-injection site care and site closure requirements that are tailored to address the unique nature of GS. The Class VI requirements,

therefore, minimize health risk s to all populations, including ch ildren. The "Risk and Occurrence Document for the Geologic Sequestration Rule making," available in the rulemaking docket, presents a broad discussion of risks to human h ealth and the environment associated with GS, including those addressed under SDWA authority and those environmental and human health impacts that are beyond the scope of the SDWA.

As part of its adaptive rulemaking approac h, EPA plans to collect and review available

information such as the research described abov e and data every six year s on early GS projects, including impacts to USDWs and dr inking water quality that may aff ect the health of children, to determine whether the appropriate amount and t ypes of information and documentation are being

collected, and to determine if modifications to the requirements are a ppropriate or necessary.

41Letter ID: 0241 Comment ID: 23276 Letter Lines: 610 to 619

Comment Code: 4324 2.4.4.1.2 Comments opposed to 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: 144.6 Class VI wells are to be limited to injection beneat h the lowermost formation containing a USDW. This arbitr ary exclusion would eliminate a vast number of potential sequ estration zones. Enhanced oil and gas recovery operations above the lowermost USDW have been taking place for a very long time.

Exclusion of these zones where other abundant supplies of freshwater are available may unnecessarily limit sequestration options. These situations are best handled locally where all the pertin ent regional geologic factors can be considered. The buoyancy of carbon dioxide suggests this in an unnecessary restriction since it would move inject ate away from the USDWs below the sequestration zone.

Individual Response: As described above, EPA acknowledges that there are limited circumstances where injection above the lowerm ost USDW can be performed in a manner that protects USDWs from endangerment, as long as appropriate protections are in place. The final GS rule at §146.95 establishes a pr ocess by which owners or operato rs can seek a waiver of the Class VI injection depth requirements for inje ction into non-USDW form ations above and/or

between USDWs.

Letter ID: 0241 Comment ID: 23277 Letter Lines: 621 to 622

Comment Code: 5700 2.12 Comments on the proposed durati on of Class VI permits (seeking comment)

Comment: 144.36 Permits for Class VI wells should be effective indefinitely, until the well is plugged.

Individual Response: The final rule maintains the lifetime permit provision and clarifies that the permit extends through the post-injec tion site care period (144.36(a)).

Letter ID: 0241 Comment ID: 23278 Letter Lines: 624 to 628

Comment Code: 1220 1.1.1.1 Terminology and definitions

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

USDW

Comment: 146.81(d) Geologic sequestra tion project should be re defined as follows: Geologic sequestration project means an in jection well or wells used to emplace a carbon dioxide stream into an injec tion zone for geologic sequestration.

42Geologic sequestration projects should not be limited to beneath the lowermost formation containing a USDW.

Individual Response: EPA has not revised the definition of a geologic sequestration project for

the final rule. However, as described above , EPA acknowledges that there are limited circumstances where injection above the lowerm ost USDW can be performed in a manner that protects USDWs from endangerment, as long as appropriate protections are in place. The final GS rule at §146.95 establishes a pr ocess by which owners or operato rs can seek a waiver of the Class VI injection depth requirements for inje ction into non-USDW form ations above and/or

between USDWs.

Letter ID: 0241 Comment ID: 23279 Letter Lines: 630 to 631

Comment Code: 1220 1.1.1.1 Terminology and definitions

Comment Code: 3110 2.1.1 Proposed siting requirements (i.e., injection/confining zones, trapping mechanism)

Comment: 146.82(a) Overlying formations needs to be defined. Geologic information should be limited to the injectio n and confining zones.

Individual Response: EPA believes that a detailed geologic al site characterization (required under §146.82) is essential to ev aluating the presence and adequ acy of the various geologic features necessary to receive and confine inje cted CO2 for GS. The requirements for geologic

site characterization are base d on a long standing UIC regulatory framework developed to address specific risks to USDWs posed by injection. The Clas s VI GS requirements are tailored so that they are appropriate for the unique nature of injecting large volume s of CO2 into a variety of geological formations for long-term storage.

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 regard ing characterizing the region al geology and hydrogeology of a proposed GS site as well as performing th e necessary geochemical, geomechanical, and geophysical analyses of the injection and conf ining zone. The guidance can be found on EPA’s website at http://water.epa.gov/type/gr oundwater/uic/wells_sequestration.cfm.

Letter ID: 0241 Comment ID: 23280 Letter Lines: 633 to 635

Comment Code: 3130 2.1.3 Comments that operators s hould submit more (or different) geologic data than proposed

Comment: Capillary pressure is difficult to m easure outside a lab and would not be

available if no wells have been drilled in a project. Do not see necessity for

this information.

43Individual Response: EPA acknowledges that laboratory met hods are standard for determining capillary pressures regardless of formation perm eability and that in si tu measurements would require drilling of a well. However, EPA also antici pates that test wells will be drilled to support geologic site characterization of the proposed GS sites and can be used to collect subsurface samples (for laboratory determination of cap illary pressure) and take other necessary

measurements. EPA believes that information on capillary entry pressure is necessary and appropriate. Capillary entry pressure measuremen ts on core samples can quantify the amount of buoyant force the confining zone can maintain befo re failure (World Res ources Institute, 2008).

EPA recognizes that this information may not be available until after a well has been drilled. EPA revised §146.82 so that the fina l 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 pr essures would be required following drilling of the well, at §146.82(c)(4).

Letter ID: 0241 Comment ID: 23281 Letter Lines: 637 to 639

Comment Code: 3140 2.1.4 Comments that the proposed ge ologic data requirements are too stringent

Comment: 146.82(g) Baseline geochemical data on s ubsurface formations is too broad. Should be limited to the injection zone, confining zones, and possibly the next porous and permeable zone above the upper confining zone.

Individual Response: The Agency believes that the re quirement at §146.82(a)(6) to submit baseline geochemical data on subsurface geologic formations, including all USDWs in the AoR is appropriate and protective of USDWs. EPA believes that this data will support monitoring plan development, inform injectate fate a nd transport model development (e.g., by providing appropriate input parameters), a nd provide information needed to respond to any unexpected and unpermitted leaks outside of the injection zone. Th e 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.

The rule requires geochemical analysis of, at a minimum, the injection zone, confining zone, and all USDWs (§146.82(a)(6)). These geochemical tests ar e necessary to ensure the adequacy of the confining system and to serve as a baseline for future monitoring. The Director has the discretion to require geochemical analysis of additional s ubsurface zones if in the Director's opinion they are necessary for the protection of USDWs from endangerment.

EPA agrees that site characterizati on should be site-specific, particul arly in light of the variety of geologic settings in which GS may be employe d. EPA believes that, while there is a large amount of required information, the owner or operat or is given flexibility in determining what methods are used to demonstrate the suitability of a potential site. EPA envisions an ongoing

44dialogue between the Director and the owner or operator during the permitting process (as well as throughout the operation of the site).

Letter ID: 0241 Comment ID: 23282 Letter Lines: 641 to 643

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

Comment: 146.82(u) Site closure plans, post-closur e plans, well plugging plans, etc., should not be required many years in adva nce since conditions, understanding of the sequestration zones, and t echnology change over time.

Individual Response: EPA disagrees with the commenter's assertion that that the timing of plan submittals should be linked to the specific activity being addressed, and believes that submittal and review of each of the owner or operator's plans required at §146.82 at the time of the permit application is necessary. While injection well plugging, post-inject ion site care and site closure will likely not occur for years after injection commences, the Director needs to have assurance that the owner or operator ha s planned for these events.

Letter ID: 0241 Comment ID: 23283 Letter Lines: 645 to 650

Comment Code: 3110 2.1.1 Proposed siting requirements (i.e., injection/confining zones, trapping mechanism)

Comment: 146.83(a)1 An injection zone capable of r eceiving the total anticipated volume

of carbon dioxide should not be an absolu te requirement. The volume to be injected may be difficult to ascertain si nce the life of a power plant or other source may change with advances in technology or under certain economic conditions. A candidate inje ction zone should not be excluded if it can only serve as a sequestration zone fo r a portion of a project.

Individual Response: The Agency disagrees with the commenter for asserting that there should not be an absolute requirement that the inje ction zone be capable of receiving the total anticipated volume of CO2. The GS rule is designed to ensure that the total volume of CO2 anticipated to be injected can be safely stored w ithin the target injection zone. This evaluation is based on site-specific characteristics includ ing the local geology (e.g., data on formation thickness, porosity, and permeability and the presence of confining zones). The GS injection requirements, under SDWA authority, ensure pr otection of USDWs from endangerment through assessment of the suitability of an injection zone (§146.83), appr opriate site characterization (§146.82), and area of review evaluati on (§146.84) among other requirements.

The Agency believes that this comment may be based on an assumption that Class VI injection

wells will be co-located with CO2 producing facilities. While this may, in some cases, be an accurate assumption, the specifications, design, a nd purpose of the CO2 source/facility are not addressed by the Class VI GS requirements.

45The productivity of the CO2 source (e.g., power plant, industrial facility, etc.) is not the driver of site suitability. Rather, the acceptability of a candi date site is determined, in part, by the amount of CO2 it can receive without allowing pressures in the injection formation to build up to levels that may fracture the confining zone or cause unacceptable fluid movement. If a CO2 source produces more than a formation can hold, then on ce the capacity of the receiving formation is reached, any additional CO2 produced would have to be injected elsewhere.

Letter ID: 0241 Comment ID: 23284 Letter Lines: 652 to 654

Comment Code: 3120 2.1.2 Need to identify additional confining and containment zones (seeking comment)

Comment: 146.83(b) Delete reference to identifica tion of additional confining zones. This implies this will be required. Redunda nt confining zones are not required

in other UIC well classes.

Individual Response: EPA clarifies that secondary confini ng zones are not required for all GS sites. Rather, secondary confini ng zones are required when the Di rector determines that these zones are needed to maximize the protection of USDWs from endangerment. EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (e.g., §146.83(b)). EPA believes that, in some situations, the presence of additional confining and containment zones above the pr imary (i.e., lowermost) confining zone can improve USDW protection. These layers could fu rther impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and

remediation.

Letter ID: 0241 Comment ID: 23285 Letter Lines: 656 to 657

Comment Code: 5430 2.9.1 Comments on proposed financia l responsibility requirements (40 CFR 146.85)

Comment: 146.85(b) The frequency specified for writte n updates of adjustments to cost

estimates should coincide with the AOR reevaluation.

Individual Response: EPA agrees that it is important to periodically update cost estimates that support financial responsibility determinations. EPA clarifies th at the GS rule, at §146.85(c) requires the owner or operator to provide annua l updates to the cost es timate to account for any amendments to the AoR and corrective action plan, the injection well plugging plan, and the PISC and site closure plan. EPA a dds that the Director can also re quire 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 specifi ed at §146.85(e). See the final rule and preamble

for further discussion of EPA's final a pproach to financial responsibility.

46Letter ID: 0241 Comment ID: 23286 Letter Lines: 659 to 659

Comment Code: 3860 2.3.3 Well component degradation

Comment: 146.86(b)1(v) How is corrosiveness measured?

Individual Response: EPA clarifies that, although corro siveness does not have a unit of measure, corrosiveness can be technically measured and described. Procedures that can identify corrosion (or the absence of corrosion) in a Class VI well provide valuable operational

information that the Director needs to determine appropriate standards for the tubing and packer.

The final GS rule at §146.86(c)(1), also requires that tubing materials us ed in Class VI wells must meet or exceed standards developed by the American Petroleum Institute, ASTM International, or comparable standards acceptabl e to the Director. EPA believes that this requirement invokes the expertis e of these bodies without the added burden of a certification

program.

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: 0241 Comment ID: 23287 Letter Lines: 660 to 669

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

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

USDW

Comment: 146.86(b)2 Requiring setting surface casing below the lowermost USDW would preclude injection above the lowermost US DW, which as earlier stated, would eliminate a vast number of potential seque stration zones. Enhanced recovery operations above the lowermost USDW have been taking place for a very long time.

Exclusion of these zones where other abundant supplies of freshwater are available may unnecessarily limit sequestration options. These situations are best handled locally where the regional geologic factors can be considered. Setting the surface casing below the lowerm ost USDW may not be technically

feasible.

Individual Response: EPA disagrees that the surface casing requirements in the GS rule preclude injection below deep USDWs. The fina l GS rule at §146.86(b)(2) requires that surface casing extend through the base of the lowermos t USDW and be cemented to the surface through the use of a single or multiple strings of casing and cement. It does not, however, specify how cementing must be accomplished, and gives flexib ility to the owner or operator to propose alternate methods- to provide a sufficient amount of cement to meet the standard that USDWs

47are protected from endangerment. EPA notes that there are many potential ways to meet the requirement, such as the use of staged cementing.

EPA adds that protection of USDWs is the pr imary mission and mandate of the UIC program and the purpose of all requirements for inject ion 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.

EPA recognizes concerns regardi ng construction of Class VI wells where the lowermost USDW is very deep. To further address comments on d eep 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 opera ting under injection depth waivers must comply with additional construction require ments to ensure that wells used to inject above or between USDWs are protective. See the discussion of the wa iver approach in the preamble to the final GS

rule for additional information.

Letter ID: 0241 Comment ID: 23288 Letter Lines: 671 to 673

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

Comment: 146.86(b)3 Cementing of the long-string casi ng to surface may not be desirable

in all situations; an annulus that can be monitored may be desirable. The longstring casing should be cemented to at least above the upper confining zone.

Individual Response: The final GS rule at §146.86(b)(3) re quires that the long-string casing extend to the injection zone and be cemented by ci rculating cement to the surface in one or more stages. It does not, however, specify how cementing would be accomplished, and gives flexibility to the owner or ope rator to propose alternate methods to provide a sufficient amount

of cement to meet the standard that USDWs ar e protected from endangerment, subject to the approval of the Director. EPA adds that, unde r §146.86(b)(4), the Dire ctor 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 th at the cement does not allow

fluid movement behind the wellbore.

See the discussion of Class VI well construction requirements in the preamble to the final GS rule for additional information. Additionally, EP A 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: 0241 Comment ID: 23289 Letter Lines: 675 to 675

Comment Code: 3820 2.3.1 Well construction procedures

Comment: 146.86(b)5 Request clarification whether a CBL with VDL image is sufficient.

48Individual Response: A cement bond log with a variable density log image is one of the methods that could be used to evaluate cement qua lity radially. Radial ev aluation of cement is generally done using acoustic instruments wh ich emit signals through a transmitter and then receive the response in receive rs. The speed at which the wave returns and the amount of attenuation provide information about the mate rial through which the waves travel. The logging and testing requirements at §146.87(a) describe the complete suite of tests to be used before and upon installation of the surface cas ing and long-string casing.

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: 0241 Comment ID: 23290 Letter Lines: 677 to 677

Comment Code: 3860 2.3.3 Well component degradation

Comment: 146.86(c)2(ii) How is corrosiveness measured?

Individual Response: EPA clarifies that, although corro siveness does not have a unit of measure, corrosiveness can be technically measured and described. Procedures that can identify corrosion (or the absence of corrosion) in a Class VI well provide valuable operational

information that the Director needs to determine appropriate standards for the tubing and packer.

Letter ID: 0241 Comment ID: 23291 Letter Lines: 679 to 681

Comment Code: 3866 2.3.3.3 Logging and testing requirements (40 CFR 146.87)

Comment: 146.87(a) Relevant geologic formations is too broad. This information should only be required for the injection and confining zones and possibly the next porous and permeable zone above the upper confining zone.

Individual Response: Regarding clarification of the term "relevant geologic formations," EPA expects that during the permit application pro cess, the owner or operator and the permitting authority will work together to determine which formations should be studied, based on the sitespecific circumstances.

EPA is developing guidance on monitoring and tes ting that will describe recommended tests and procedures to assist owners/operators and Di rectors 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: 0241 Comment ID: 23292 Letter Lines: 683 to 684

49Comment Code: 3866 2.3.3.3 Logging and testing requirements (40 CFR 146.87)

Comment: 146.87(a)2 Open hole logs in the surface hol e are unusual and not necessary. If required, certainly not in ev ery well in a project.

Individual Response: Many types of logs (e.g., potential lo gs) cannot be run in a cased hole. Because the borehole for the surface casing runs through the lowermost USDW, it is imperative that the geology, lithology, and geochemistry of s ubsurface formations be defined. EPA adds that this type of testing has been successfully performed on Class I hazardous wells. EPA acknowledges that, while use of these logs may be unusual in oil and gas fiel ds with a lot of data,

it would be essential to identif y these shallow USDWs or other zones in areas where Class VI wells could be drilled. Running caliper logs in surface holes also established a benchmark for determining adequate cement to be placed in the well.

Letter ID: 0241 Comment ID: 23293 Letter Lines: 686 to 686

Comment Code: 3866 2.3.3.3 Logging and testing requirements (40 CFR 146.87)

Comment: 146.87(a)3 Should specify basic logging requirement not specific logs.

Individual Response: EPA has conducted extensive research and has found that the tests and logs specified at §146.87(a) have been proven inindustry practice and re search to identify cementing flaws. EPA adds that these tests ar e necessary to verify information about the injection and confining zones, and ensure that th e well is being drilled and cased as approved and has mechanical integrity. This information demons trates that the well can be operated and tested in a manner that will meet the requirements for Class VI wells. Should alternative methods be shown to provide equivalent or better informa tion, the Director may allow such alternatives under §146.87(a)(5).

Letter ID: 0241 Comment ID: 23294 Letter Lines: 688 to 691

Comment Code: 3866 2.3.3.3 Logging and testing requirements (40 CFR 146.87)

Comment: 146.87(b) Coring should not be required if an adequate core and report exists for a nearby well. Coring should only be required of the injection and confining zones and possibly the next por ous and permeable zone above the upper confining zone.

Individual Response: EPA clarifies that §146.87(b) allows information on cores from nearby wells to be submitted if the owner or operator can demonstrate that core retrieval is not possible and that cores from nearby wells are representa tive of conditions at the Class VI well.

Letter ID: 0241 Comment ID: 23295 Letter Lines: 693 to 693

50Comment Code: 3866 2.3.3.3 Logging and testing requirements (40 CFR 146.87)

Comment: 146.87(d)2 Vague and ambiguous.

Individual Response: EPA believes that flexibility on this requirement is warranted to account for the variety of geologic conditi ons that may be encountered at GS sites. The owner or operator must describe in the permit application, pursuan t to §146.82(a)(8) the proposed formation testing program, including how he or she would meet the requirements of §146.87(d). The Director will evaluate the proposed formation testing plan, al ong with site-specific geologic and geochemical information. EPA is developing guidance on mo nitoring and testing that will describe recommended tests and procedures to assist ow ners/operators and Dire ctors in evaluating the requirements for pre-operational logging a nd 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: 0241 Comment ID: 23296 Letter Lines: 695 to 696

Comment Code: 3866 2.3.3.3 Logging and testing requirements (40 CFR 146.87)

Comment: 146.87(f) Unrealistic time frame. Tie initial reporting to spud date and 48

hour notification thereafter.

Individual Response: EPA disagrees that the 30-day notif ication requirement is unreasonable. The 30-day notification mirrors the current requ irement for logging and testing of new Class I wells, as described in §146.66. Acknowledging the developing nature of CO2 GS, EPA believes that involvement by the permitting authority in each project will provide much needed field data for assurance of USDW protec tion from endangerment and will help update and refine the permitting process. Adequate timing of notification will ensure the Director's ability to be

involved.

Letter ID: 0241 Comment ID: 23297 Letter Lines: 698 to 701

Comment Code: 4100 2.4.1 Injection parameters

Comment: 146.88(c) Pressure on the annulus is not necessary in all situations. Maintaining pressure above the injecti on pressure will subject the long-string casing to unnecessary stress and is not commensurate wi th the risk associated with carbon dioxide injection.

Individual Response: EPA believes that maintaining an annulus pressure that is higher than the injection pressure, as required at §146.88(c), will ensure that if there are leaks in the tubing, the annulus fluid will move into the tubing, rather than the injectate moving out of the tubing and potentially along the outside of the well. EPA belie ves this requirement is appropriate for Class VI wells given the potential high volumes and superc ritical nature of the CO2 injectate, potential geomechanical stresses in the wellbore, and the potential for movement of the CO2 in the event

51of a mechanical integrity loss.

EPA does not believe that maintaining annulus pressures that exceed the injection pressure would cause unacceptable stress on the casing. A pr operly designed well that takes into account the geologic and geomechanical properties of the site based on information collected under §146.82 and meets the construction requirements at §146.86 would be able to maintain integrity if the annulus pressure were reasona bly higher than injection pressure.

Letter ID: 0241 Comment ID: 23298 Letter Lines: 703 to 703

Comment Code: 4100 2.4.1 Injection parameters

Comment: 146.88(e) Is continuous record ing of annular fluid volum e possible or practical?

Individual Response: EPA believes that knowing annulus fluid volume, as required at §146.88(e), is a necessary component of monitoring well mechanical integrity, but believes that monitoring the annulus fluid volume added is su fficient to meet the intent of continuous monitoring of the pressure on th e annulus. The final GS rule at §146.90 (b)) requires that owners or operators use continuous reco rding devices to monitor injecti on pressure, rate and volume; the pressure on the annulus between the tubing and the long string casing; and the annulus fluid

volume added.

Letter ID: 0241 Comment ID: 23299

Comment: Individual Response:

Letter ID: 0241 Comment ID: 23300 Letter Lines: 712 to 713

Comment Code: 4546 2.5.2.2 MIT frequency (seeking comment)

Comment: 146.89(c) Annual tracer surveys, temperature or noise logs, or casing inspection logs is too burdensome. This frequency should coincide with AOR reevaluation.

Individual Response: The final GS regulation retains the re quirement that owners or operators of Class VI wells demonstrate injection well exte rnal mechanical integrit y at least once annually at §146.89(c). EPA believes this is justifiable for the protectio n of USDWs from endangerment given the unique nature of CO2 GS relative to other injection operations, including the potential corrosive impact of CO2 in the presence of water and impurities on well materials, the potential geomechanical impacts to well integrity due to CO 2 phase changes, the temperature and pressure effects associated with injecti ng supercritical CO2, and the buoyant nature of the injected CO2. Because of the unknown long-term effects of CO2 GS, EPA chose a more conservative initial approach in the early stag es of deployment for GS.

52In addition, a comprehensive review conducte d by EPA of MIT results from 1993 to 1998 found that Class I wells injecting corrosi ve fluids fail MITs at rates two to three times higher than those that inject non-corrosive fluids (USEPA 1999). Given the potentia l for CO2 to be corrosive (e.g., in the presence of water or aqueous formation flui ds), there is a potential risk factor for MIT

failure and, for this reason, EPA be lieves that the tailored MIT requi rements in the final GS rule are appropriate.

EPA agrees that the casing inspection log is not an appropriate test to detect fluid movement behind the casing, but clarifies that it is appropriate for determin ing the presence or absence of corrosion of the long-string casing, and is required if the Director determin es that it is necessary based on site-specific information. EPA has revi sed the final GS rule to require that the frequency of the casing inspection log must be specified in the approve d testing and monitoring plan. See §146.89(d).

EPA adds that it is using an adaptive approach to regulating GS. The Agency will, every six years, collect and review data on GS projects , including MIT data, to determine whether the appropriate amount and types of information a nd appropriate documentation are being collected,

and to determine if modifications to the requirements are appropriate or necessary.

Letter ID: 0241 Comment ID: 23301 Letter Lines: 715 to 715

Comment Code: 4620 2.6.2 Injectate monitoring

Comment: 146.90(b) Is continuous recording of annular fluid volume possibl e or practical?

Individual Response: EPA believes that knowing annulus fluid volume, as required at §146.88(e), is a necessary component of monitoring well mechanical integrity, but believes that monitoring the annulus fluid volume added is su fficient to meet the intent of continuous monitoring of the pressure on th e annulus. The final GS rule at §146.90 (b)) requires that owners or operators use continuous reco rding devices to monitor injecti on pressure, rate and volume; the pressure on the annulus between the tubing and the long string casing; and the annulus fluid

volume added.

Letter ID: 0241 Comment ID: 23302 Letter Lines: 717 to 718

Comment Code: 4630 2.6.3 Corrosion monitoring

Comment: 146.90(c) Quarterly is too oner ous. Director should have discretion to require less frequently based upon performance.

Individual Response: EPA believes that quarterly corrosion monitoring is appropriate given the potentially corrosive nature of the CO2 stream. CO2 in the presence of water becomes acidic, potentially accelerating corrosion of well material s. The CO2 stream for a GS project may also

53contain small volumes of impurities that could co ntribute to corrosion. For these reasons, the final rule requires quarterly corro sion monitoring, at §146.90(c).

Letter ID: 0241 Comment ID: 23303 Letter Lines: 720 to 720

Comment Code: 4700 2.7 Proposed Recordkeeping and Reporting Requirements (40 CFR 146.91)

Comment: 146.91(a) Injection volumes and pressu res should be reported monthly.

Individual Response: The final rule remains unchanged from the proposal and requires semiannual reporting of monthly average, maximum and minimum values for injection pressure, flow rate and volume, annular pressure, and monthl y annulus fluid volume added at §146.91(a). EPA believes that monthly reporting of routine operational data and monitoring results would provide no additional protection of USDW s from endangerment. EPA adds , at §146.91(c), that it has included in the final rule a requirement that ope rators must report with in 24 hours of any event that may endanger USDWs; noncompliance with a permit condition or malfunction of injection system which triggers fluid movement; any tr iggering of a shut-off system; any failure to maintain mechanical integrity; or if anything is detected through surface/air monitoring, if its required. EPA notes that states seeking primacy for Class VI wells are free to require more frequent reporting.

Please see the final rule and the discussion of testing and monitoring in the preamble for

additional information.

Letter ID: 0241 Comment ID: 23304 Letter Lines: 722 to 724

Comment Code: 4740 2.7.4 Electronic reporting (seeking comment)

Comment: 146.91(c) Electronic reporting should not be required. State systems may already be in place to collect data but may not be compatible with sending or receiving systems.

Individual Response: EPA believes that electronic formatting is the most appropriate format for submitting Class VI project information to the Director, and based on comments received on the proposed rule, the majority of Class VI well owners or operators will have the capability to report electronically, and re quires this at §146.91(e).

Acknowledging that some States may have to develop electronic data systems to receive

electronic information from the owner or operator, and that many States which already have electronic data systems will have to make ch anges to accommodate a new class of UIC well (Class VI), EPA believes that it is prudent to provide assi stance by develo ping a central framework for the electronic system that will be used by States to gather and track owner or operator data. This will enable owners or opera tors to submit data without having to wait for a State to develop a system. It will also provide for standardized submissions across the country

54and enable States to focus State resources on re viewing and approving permit applications rather than building or upgrading separate, inde pendent databases for GS information.

EPA is developing guidance for states that describes the recordkeeping, reporting, and additional data management needs associated with GS act ivities and provides recommended guidelines on the types of data to be collected for tracki ng GS projects, reporti ng to EPA for compliance tracking, and transfer of data to EPA's GS data system. The recordkeeping and reporting guidance will be available on EPA's web site, at http://water.epa.gov/type/groundwater /uic/wells_sequestration.cfm.

Letter ID: 0241 Comment ID: 23305 Letter Lines: 726 to 727

Comment Code: 5100 2.8.1 Injection well plugging activ ities (seeking comment) (40 CFR 146.92)

Comment: 146.92(d) Simplify. Plugging reports should be required within a consistent

time frame.

Individual Response: EPA has revised the text at §146.92(d) to reduce confusion. The final rule text reads, "Within 60 days afte r plugging the owner or operator must submit a plugging report to

the Director."

Letter ID: 0241 Comment ID: 23306 Letter Lines: 729 to 731

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

Comment: 146.93(b) A performance-based time period is appropriate rather than a fixed timeframe. Establishing an arbitrary a nd long time frame will inhibit operators from entering into this activity.

Individual Response: EPA acknowledges that there will be circumstances where it can be demonstrated in less than 50 years that the pl ume and pressure front no longer pose a risk of endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during the pos t-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 ensu res non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from enda ngerment, a default timeframe for post-injection site care will be necessary in al l but a limited number of cases. This default 50 year post-injection site care ti meframe represents a reasonable and protective monitoring period

based on a review of research studies, industr y reports, and existing environmental programs, and evaluation of public comments.

5556 EPA believes that a default post-injection site car e 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 ac commodate site-specific circumstances and various geologic conditions, and addre sses commenters’ concerns, wh ile ensuring USDW protection. Both approaches will utilize si te-specific data, and be based on pressure monitoring and USDW impacts.