The comments below reflect interagency review of the draft rule under EOs 12866 and 13563. They are subject to further policy review.

Page 1 of 11 Global Comments

1. EPA appears to be extending its authority into implementation of the 40 CFR Part 192 standards, which oversteps its authority under the Atomic Energy Act (AEA). The AEA confers jurisdiction over the operations of conventional, heap leach, and in situ uranium recovery facilities where source material is milled or processed on the U.S. Nuclear Regulatory Commission (NRC). As discussed in Section 275(b) of the AEA, the Uranium Mill Tailings and Radiation Control Act of 1978 (UMTRCA) amended the AEA to give EPA the authority to develop generally applicable standards for protection of public health, safety, and the environment from the radiological and non-radiological hazards associated with processing and with the possession, transfer, and disposal of byproduct material at sites where ore is processed primarily for its source material content or at site which are used for the disposal of such byproduct material. EPA’s generally applicable standards are contained in 40 CFR Part 192. Section 275(d) states that “[i]mplementation and enforcement of the standards promulgated pursuant to subsection b. of this section shall be the responsibility of the [NRC] in the conduct of its licensing activities under this Act.” Section 84 of the AEA directs the NRC to develop standards that conform to EPA’s general standards. The NRC’s conforming standards are contained in 10 CFR Part 40, Appendix A.

Throughout the revisions to 40 CFR Part 61 in this draft proposed rule, EPA proposes that it will be responsible for ensuring that liner requirements under 40 CFR 192.32 are met. We interpret that the following statements would authorize EPA to review and approve liner system designs for impoundments at uranium re covery facilities and would be duplicative of and create a conflict between the NRC’s implementation of EPA’s generally applicable standards and the proposed regulations: “[t]hird, we are proposing to clarify what specific liner requirements in 40 CFR 192.32 apply and that EPA, rather than NRC, will ensure those requirements are met under subpart W.” (page 48 – 49); and “[h]owever, when referenced in Subpart W, the requirements in 40 CFR 192.32(a)(1) would also be implemented and enforced by EPA as the r egulatory authority administering Subpart W under its CAA authority.” (page 97)(note that several other locations within the document, such as pages 71, 72, 74, 96, and 97, discuss the relationship between the 40 CFR Part 192 standards and 10 CFR Part 40, Appendix A, requirements). However, statements on pages 74, 98, and 107 of the proposed revisions correctly point out that the 40 CFR Part 192 standards are currently implemented and enforced by the NRC. It is unclear to us what additional benefit would be obtained by implementing the 40 CFR Part 192 standards under the CAA as uranium recovery facilities are already subjected to these standards. The NRC’s conforming regulations in 10 CFR Part 40, Appendix A, currently require installation of liner systems to protect groundwater re sources in the vicinity of an impoundment. Additionally, the aspect of the proposed rule requiring both NRC and EPA implementation of the 40 CFR Part 192 standards may lead to more confusion because while NRC’s 10 CFR Part 40, Appendix A, standards conform to the 40 CFR Part 192 standards (including the cross reference to 40 CFR 264), the Appendix A standards are not identical to the 40 CFR Part 192 standards. Note the NRC’s final rulemaking related to the development of groundwater protection standards for uranium recovery facilities (52 FR 43553; November 13, 1987) includes a table identifying the applicable EPA regulation, subject, and location of the comparable NRC regulation in Appendix A.The comments below reflect interagency review of the draft rule under EOs 12866 and 13563. They are subject to further policy review.

Page 2 of 11 EPA Response : EPA agrees that under UMTRCA, it has the authority to promulgate standards applicable to uranium recovery facilities, and NRC has the authority to implement and enforce these standards through its licensing activities. See 42 U.S.C. §§ 2022(b), 2022(d); 40 CFR Part 192. However, as explained in Sections II.A. and II.B. of the Subpart W proposed rule, EPA also has authority under the Clean Air Act (CAA) to regulate the

emissions of radionuclides from these same facilities. EPA originally promulgated 40 CFR Part 61, Subpart W, in 1989 under its CAA section 112 authority, and it is under that authority that EPA now acts to propose revisions to Subpart W.

EPA’s authority under the CAA includes the authority to implement and enforce the standards it promulgates. Subpart W, as pr omulgated in 1989, requires uranium recovery facilities to comply with certain Part 192 requirements. Specifically, Subpart W currently requires: “All mill owners or operators shall comply with the provisions of 40 CFR 192.32(a) in the operation of tailings piles, the exemption for existing piles in 40 CFR 192.32(a) notwithstanding.” 40 CFR 61.252(c); see also discussion in Section II.E. of proposed rule. The fact that EPA cross-references the Part 192 requirements in Subpart W does not change the authority EPA is acting under when requiring compliance with these requirements. EPA is acting under the CAA when it includes these Part 192 requirements in Subpart W. Cross-referencing these provis ions instead of copying them directly into Subpart W is done as a matter of convenience and is a convention often used in rulemakings. The proposed revisions clarify the particular Part 192 requirements that apply to uranium recovery facilities under Subpart W.

EPA does not believe that its proposed revisions to Subpart W will lead to confusion as to the requirements that uranium recovery facilities must meet. The proposed revisions to Subpart W simply clarify the particular Part 192 requirements that apply. The proposed revisions also propose that uranium recovery facilities keep records that confirm that the conventional impoundments, nonconventional impoundments and heap leach piles meet the requirements in 40 CFR 192.32(a)(1), which we have incorporated by reference into Subpart W. See 40 CFR 61.255(a) in the proposed rule. These recordkeeping requirements help assure compliance with the requirements of Subpart W. If we adopt the proposed recordkeeping requirements in Subpart W, EPA expects that most facilities will demonstrate compliance with the Part 192 requirements in Subpart W by showing compliance with the same requirements for NRC purposes. The recordkeeping requirements included in the proposed rule are not burdensome and enable EPA to assure compliance with the requirements of Subpart W. As has been the case since 1989, EPA can take enforcement action if necessary under its CAA regulatory authority if the requirements of Subpart W are not met.

2. EPA lacks the authority to assume jurisdiction over heap leach uranium recovery operations. On page 23 of the proposed rule, EPA states that it is proposing to regulate heap leach uranium extraction under Subpart W. As EPA appropriately described, the heap leach treatment processes uranium ore in such a manner that the uranium content is removed. Licensing and regulatory authority ov er this process rest with the NRC pursuant

to the AEA.

EPA Response : We disagree that EPA lacks the authority to regulate radon emissions from the heap leach pile under the CAA. See discussion in Section IV.B.4 of the proposed rule. While we agree that NRC possesses the licensing authority pursuant to the AEA, EPA has authority under the CAA to regulate radon emissions generated from the uranium byproduct material in the heap leach pile, and we are exercising that authority in theThe comments below reflect interagency review of the draft rule under EOs 12866 and 13563. They are subject to further policy review.

Page 3 of 11 proposed rule. Regulating radon emissions from heap leach piles is no different than regulating radon emissions from uranium bypr oduct material in conventional tailings impoundments or evaporation ponds. As discussed in Section IV.B.4 of the proposed rule,

EPA believes that once the extraction solution re moves uranium from the ore, what remains is uranium byproduct material; thus, under the CAA, EPA may require such facilities to limit radon emissions from the heap leach pile.

3. Various definitions may not be consistent with other regulations or used consistently within the proposed rule and could lead to confusion. The AEA, UMTRCA, 40 CFR Part 192, and 10 CFR Part 40 all define byproduct material as “[t]he tailings or wastes produced by the extraction or concentration of uranium or thorium from any ore processed primarily for its source material content.” However, Subpart W defines uranium byproduct material or tailings as the waste produced by the extraction or concentration of uranium from any ore processed primarily for its s ource material content. Under the Subpart W definition, all byproduct material are tailings, which is a different from the approach taken in the AEA, UMTRCA, 40 CFR Part 192, and 10 CFR Part 40. Our interpretation under the AEA, UMTRCA, 40 CFR Part 192, and 10 CFR Part 40 is that tailings are merely one type of byproduct material. In addition to using a different definition, the proposed rule revisions do not appear to use the terms “byproduct material” and “tailings” consistently. For example, page 18 of the document discusses evaporation or holding ponds that contain byproduct material, page 49 discusses ponds that contain tailings (but the material is liquid byproduct material), and page 53 uses both terms “byproduct material” and “tailings” in the title and following paragraph. We also observe that the proposed rule uses several different terms when referring to structures that contain byproduct material (impoundment, mill tailings pile, evaporation pond, holding pond, heap leach pile, tailings impoundment, collection pond, non-conventional impoundment). We agree that it does not particularly matter what the structure is called; however, it may be helpful to identify and define one term near the beginning of the proposed rule and use it consistently throughout the document. We observe that the definition of a surface impoundment in 10 CFR Part 40, Appendix A, may be an appropriate term to use.

EPA Response : The various definitions for impoundments in the proposed rule were defined specifically to avoid confusi on among the owners and operators of uranium recovery facilities. Many have argued that Subpart W did not apply to evaporation ponds because they did not hold “tailings.” However, by defining “uranium byproduct material or tailings” in the original Subpart W final rule (see 40 CFR 61.251(g)), as well as proposing definitions for the types of pits, ponds or impoundments that hold the uranium byproduct material or tailings (see the proposed definitions of these terms in 40 CFR 61.251), we believe operators understand whether they fall under the regulatory umbrella of Subpart W. We attempted to maintain consistency with the definition of impoundment as found in the RCRA program, and by reference, under EPA’s definitions in 40 CFR Part 192.The comments below reflect interagency review of the draft rule under EOs 12866 and 13563. They are subject to further policy review.

Page 4 of 11 4. Concern about timing as to when Subpart W would apply. On page 86 of the proposed rule, EPA states its intention to have Subpart W apply as soon as lixiviant is placed on a heap leach pile. This approach may lead to challenges from an operational standpoint. Based on discussions with potential operators, we understand that lixiviant may be applied on different portions of a heap pile at different times, which would allow a portion of the pile to drain. Additionally, an operator may propose to place ore in multiple lifts of material, so it may be possible to end up with a situation where material not yet subject to Subpart W overlies material subject to Subpart W. From a regulatory compliance perspective, it may be more practical to follow the approach proposed on pages 91 and 92. Under this approach, Subpart W would apply after the final rinse of a heap leach pile is complete. Note that the definition of tailings in UMTRCA and 40 CFR Part 192 is “[t]he remaining portion of a metal-bearing ore after some or all of such metal, such as uranium, has been extracted.” We observe that under this definition, ore is considered to be tailings after the uranium has been extracted, not when it is in the process of being extracted.

EPA Response : EPA agrees that there may be comments on our interpretation of when material in the heap leach pile becomes subject to the requirements of Subpart W. It is important to note that since this is a proposed rule, we specifically laid out several options for regulation of the byproduct material in a heap leach pile. Our preferred option is to require regulation of the heap as soon as the material in the heap contains uranium byproduct material. We recognize, however, that some commenters may disagree with this approach, and argue that the material only becomes a waste when it is no longer used for the purpose for which it was intended. EPA w ill carefully consider all comments before making a determination in the final rule.

5. Concern about the 30 percent moisture content requirement for heap leach piles. EPA is proposing that heap leach piles maintain a minimum moisture content of at least 30 percent to minimize radon emissions. We have several comments related to this proposed requirement:

General EPA Response : There are a few general stipulations that are common to all of the responses below. They are summarized here.

First, it is important to understand that the basis for applying the 30% moisture content requirement to a specific heap leach pile is very much dependent on the characteristics of the pile itself. Some of the pile’s characteristics that might influence the application of the requirement include the topography of the site, the site’s net evaporation rate, the pile’s height, the ore’s initial moisture content, permeability of ore, etc. Because of this dependency, each site will be affected differently by the 30% moisture content GACT, making it difficult to provide generic responses to some of the comments.

Second, it is recognized that imposing a 30% moisture content requirement on the pile might (and likely, would) require certain design changes to the pile (e.g., lower slopes, higher liquid application rates, additional monitoring, etc.). Nonetheless, as described in the specific responses, it is believed that successful designs can be developed.

Finally, it may be feasible that for some piles, the 30% moisture content requirement could be applied in a stepped manner. For example, the 30% moisture content might only be applied to the top “×” feet of the pile, where “×” feet would be determined on a site by site basis. Or, if there are inter-lift liners in a multi-lift pile, the 30% moisture content requirement might only apply to the top lift.The comments below reflect interagency review of the draft rule under EOs 12866 and 13563. They are subject to further policy review.

Page 5 of 11  Comment: EPA should provide an objective, or goal, for radon emissions at heap leach piles. This would allow potential commenters to compare the reduction afforded by the 30 percent moisture content criterion. Without a goal or objective, it is unclear how EPA will judge any information submitted, and no basis is given for people to supply the further information that is requested. The reduction factor is a critical factor in assessing the risk from radon emissions from a heap leach pile. It is not clear if there is any data available ( either actual data or modeling) demonstrating that a 30 percent moisture content requirement provides sufficient reduction in

radon emissions.

EPA Response : The goal of the 30% moisture content requirement is not so much to reduce the radon flux, as it is to prevent the flux from increasing. When moisture is introduced the radon flux first increases due to an increasing emanation (diffusion) coefficient and then, as more moisture is applied, the radon flux decreases due to the reduced diffusion coefficient. The figure below shows that the radon flux is a maximum at

about 8% moisture content, and that at 30% moisture content the flux is back below what it is for dry ore. In other words, since the heap leaching process intentionally introduces

moisture to the ore and since that moisture can result in an increased radon flux, the 30% moisture requirement is an attempt to ensure that heap leaching will not enhance the release of radon over what would occur from the dry ore.

Therefore, the objective or goal of this GACT is to maintain the radon flux during the heap leach process at or below the flux from dry ore.

We have not being able to identify, so far, “actual” data associated with radon emissions from a heap leach operation. There were a couple of novice attempts at heap leaching in the 1980's in the Gas Hills of Wyoming. These piles were composed of low-grade ore and overburden that was saturated with an acidic leaching solution. The resulting uranium rich solution was recovered and processed. There were no licensing conditions requiring radonThe comments below reflect interagency review of the draft rule under EOs 12866 and 13563. They are subject to further policy review.

Page 6 of 11 emission measurements (to our knowledge) associated with this specific operation. Rather track-etch canisters were placed a strategic down-wind points. The continuous and sometimes violent winds in this area of Wyoming caused sufficient mixing of the atmosphere to make any data extrapolation to the radon emission from the heap leach pile unreliable to reference. Often upwi nd radon measurements exceeded downwind radon

measurements.

Additionally, there were several low-grade ore piles that were established within the perimeter of mill tailings impoundments. These lo w grade ore piles were leached by various solutions. However, no radon emission data specific to these operations were collected. Rather perimeter radon monitoring as well as beach monitoring data were collected. Again attempting to apply any of these radon measurements to the presence of the heap leaching area would be scientifically invalid.

In the absence of operational data, it is difficult to establish a performance standard for radon emissions for heap leach sites. This apparent data void, resulted in the performance standard of a 30% moisture requirement. This moisture requirement has been determined to appropriately reduce radon emissions (see Figure 16, on Page 72).

We recommend that “actual” data ought to be collected from an operational site to determine the effect of the 30% moisture requirement.. An operational license condition may need to be included in the licensing package to monitor the moisture content and the radon emission. Comparison of these data with background conditions will allow a scientific

determination of radon emission and risk to be evaluated.

 COMMENT: EPA should provide its estimate of the reduction factor for radon emissions that would be obtained by the 30 percent moisture content requirement. We observe that such an estimate was provided for the requirement for 1 meter of water covering nonconventional impoundments.

EPA Response : The reduction factor associated for radon emissions from water covered impoundments can be calculated by the well known radon attenuation equation, shown as Equation 6-1. The water radon attenuation factor is independent of the site’s location and all other site specific characteristics, and depends only on the depth of the water cover.

Contrary to this, the radon reduction factor resulting from the application to the 30% moisture content GACT is heavily dependent on each site’s characteristics. As the figure

below shows, at 8% moisture content the radon flux is a maximum of about 2.3 times the dry ore flux. At 30% moisture content the radon flux has been reduced to below the dry ore flux. Therefore, this GACT results in a potential 2.3 reduction in the radon flux from the heap leach pile. Of course the exact reduction will depend upon the specific heap pile. For example, if a heap pile is operating at 20% moisture content without the GACT, then imposing the GACT would result in a radon flux reduction of about a factor of 1.6. Also, (see below), the response of the radon emanation coefficient to increasing moisture is very dependent on the material. This relationship between the emanation coefficient, moisture content, and material also influences the amount of reduction provided by the GACT.The comments below reflect interagency review of the draft rule under EOs 12866 and 13563. They are subject to further policy review.

Page 7 of 11 As we cited earlier, the 30% moisture content effectiveness can be determined based on operational data, if and when heap leach sites are built and operated. An operational license condition may need to be included in the licensing package to monitor the moisture

content and the radon emission.

 COMMENT : The moisture content within a heap pile is variable with time and heap leach piles are designed to drain, so it is not clear how the moisture content could be maintained above 30 percent once liquid application has stopped.

EPA Response : Of course, the moisture content of a heap leach pile is continuously changing, from saturation to some percentage of moisture. It is very likely (more probably assured), that in the western United States semiarid areas that the upper layer of the heap leach may reach air-dry moisture content which is much less than the 30% moisture content that has been established. The high evaporation rate, combined with brisk winds and almost constant sun will result in rapid drying of the surfaces of heap leach sites. This is particularity the case in the semiarid western United States, where there is the highest probability of a viable heap leach industry. To manage the drying that took place licensees were required, by license condition, to sprinkle beach areas, or otherwise maintain a water cover. This operation reduced radon exhalation and minimized the dispersal of wind-blown tailings. Operational inspections by regulatory individuals noted that this was a labor intensive and effective process, if the appr opriate effort was devoted to the management practice.

To manage the 30% moisture requirement an operational license condition may need to be implemented. The actions associated with the license condition will need to be assessed during the active heap leaching cycle to determine what response is appropriate to reasonably maintain the 30% moisture requir ement. Numerous environmental conditions are present in the semiarid high desert areas of the western United States. High summerThe comments below reflect interagency review of the draft rule under EOs 12866 and 13563. They are subject to further policy review.

Page 8 of 11 temperatures are countered by below zero conditions in the winter. Additionally, near constant winds which are sometimes violent are not uncommon. Maintaining the moisture content at a predetermined value will be an operational challenge that will be unique to each heap leach site.

In order to maintain the 30% moisture content once liquid application has stopped (i.e., after active uranium leaching has ceased), it will be necessary for the licensee to continue to apply water to the pile. Because the purpose of the 30% moisture content requirement is to reduce radon emissions, and because radon emissions occur mainly from the top surface of the pile, it would not be necessary to maintain the entire pile at 30% moisture content, but only the upper portion of the pile. The exact depth to which the 30% moisture content requirement would apply would be determined on a site by site basis.

After active uranium leaching has ceased a final engineered cover would be constructed over the exhausted heap leach pile. Similar to the reclamation cover that was constructed over the Gas Hills heap leach piles, a final heap leach pile engineered cover would contain a radon barrier layer. Once the engineered cover has been constructed, than the 30% moisture content requirement would be withdrawn.

 COMMENT: Potential operators have described using multiple lifts within a heap leach pad; it is not clear how the 30 percent requirement would be applied in this

situation.

EPA Response : Heap leach operations routinely utilize multiple lifts of ore. Commonly the ore is end dumped into the leaching area and then spread into a lift of varying thicknesses. This process does not lack science, in that ore simply needs to be placed into the leaching area. Each truck load of ore contains some degree of moisture; however, it is unlikely that incoming ore would have moisture content at or above the 30% level. To assure a 30% moisture content of the ore, an operational condition may need to be established during the licensing process and implemented at the site. Each lift will need to be monitored and have the moisture amended accordingly. In addition, it is important to manage the moisture content so as to minimize the compaction of the ore. The heap leach operator needs to avoid compacted areas of ore that could slow the movement of leaching solutions. Considering this situation and the 30% moisture requirement, the heap leach operator would add moisture as required.

Since the purpose of the 30% moisture content requirement is to control the radon emissions, it may not be critical to maintain the 30% moisture content in the lower lifts/levels of the pile. The reason for this is two-fold; first, radon generated in the lower lifts would have to travel further in the pile before it would escape to the atmosphere, thereby giving it more time to decay within the pile, and second, radon from the lower layers will be slowed due to the 30% moisture content in the upper lift layers.

Additionally, in some cases inter-lift liners are provided when the pile is composed of multiple lifts (Thiel and Smith 2004). If that is the case, the inter-lift liner would act as a barrier to the emission of radon from the lower lifts, and thus mitigate the need for those

lower lifts to maintain the 30% moisture content.

Thiel, Richard, and Mark E. Smith, 2004, “State of the Practice Review of Heap Leach Pad Design Issues,” Geotextiles and Geomembranes, 22(5): 555-568.The comments below reflect interagency review of the draft rule under EOs 12866 and 13563. They are subject to further policy review.

Page 9 of 11  COMMENT: The 30 percent moisture content requirement appears to be based solely on radon emissions and does not appear to take into account the engineering properties of heap materials. This could result in slope stability or other operational issues within a heap.

EPA Response : It is agreed that the 30% moisture content requirement will impact the design of the heap leach pile. Principal concerns to be addressed during pile design are slope stability and the liquefaction potential. The impact that 30% moisture content will have on each of these parameters must be addressed during pile design. Nonetheless, it is believed that heap leach pile can be successfully designed, constructed, and operated with

30% moisture content mandate.

Regarding slope stability, many leach piles ar e provided with containment dikes which provide structural support to the pile. These dikes would not be affected by the 30% moisture content requirement, and thus would continue to provide support. Additionally, the pile design may be altered to increase its stability. For example, lower slopes, higher confinement dikes, the construction of stair-step pad grade, or the installation of textured (as opposed to smooth) geomembrane liner in critical areas would enhance pile stability.

The 30% moisture requirement will have little or no effect on the moisture requirements associated with the containment dikes. The containment dikes represent geotechnical structures that are constructed in compacted lifts to assure stability of the dikes

Regarding liquefaction potential, it has been estimated that liquefaction is unlikely if the degree of saturation in the pile is less than about 85% (Sassa 1985, as referred to in Smith 2002, Thiel and Smith 2004). Assuming a 2.7 ratio between moisture content and saturation (NRC 1984), the 30% moisture content require translates into 81% saturation, which is slightly below the level required for liquefaction. Needless to say, with the increase in the saturation that will result from the imposition of the 30% moisture content requirement, more attention will need to be paid to the pile design to minimize the liquefaction potential.

NRC (U.S. Nuclear Regulatory Commission) 1984. “Radon Attenuation Handbook for Uranium Mill Tailings Cover Design,” V.C. Rogers, K.K. Nielson, Rogers and AssociatesEngineering Corporation, and D.R. Kalkwarf, Pacific Northwest Laboratory, NUREG/CR3533, PNL-4878, RAE-18-5, April 1984.

Sassa, K. 1985. The mechanism of debris flows. Proc. of the 11th Intl. Conf. on Soil Mech. and Foundation Engineering, San Francisco, V. 3, pp. 1173-1176.

Smith, Mark E., 2002, “Liquefaction in Dump Leaching,” Mining Magazine, July 2002.

Thiel, Richard, and Mark E. Smith, 2004, “State of the Practice Review of Heap Leach Pad Design Issues,” Geotextiles and Geomembranes, 22(5): 555-568.

 COMMENT: We attempted to verify the make-up water application rate calculation on pages 89 and 90. It appears that the makeup water rate is close to the evaporation rate. If that is correct, the makeup water would be sufficient to make up for that water lost to evaporation. However, that does not mean that the water flow rate through the heap leach pile is sufficient to keep the pile at 30 percent moisture. The water flow rate required to keep moisture content at 30 percent would be based on how fast the water percolates through the heap leach pile. It appears that EPA has not provided any basis for concl uding that a flow rate of 0.005 gpm/ft 2 is sufficient to maintain 30 percent moisture.The comments below reflect interagency review of the draft rule under EOs 12866 and 13563. They are subject to further policy review.

Page 10 of 11 EPA Response : We are proposing as GACT that the heap leach pile constantly maintain a moisture content of at least 30% by weight. By requiring a moisture content of at least 30%, the byproduct material in the heap leach pile will not become dewatered, and we think that the heap leach pile will be sufficiently saturated with liquid to reduce the amount of radon that can escape from the heap leach pile. We have defined this moisture content as sufficient in earlier rulemakings, and it is defined in the current Subpart W rule

. However, we are requesting further information on all the chemical mechanisms in place during the leaching operation, and whether the 30% moisture content is sufficient for minimizing radon emissions from the heap leach pile. We are also requesting comment on the amount of time the 30% moisture requirement should be maintained by a facility. We are proposing the term “operational life” of the facility. We are aware of several operations that take place during the uranium extraction process at a heap leach pile. After an initial period of several months of allowing lixiviant to leach uranium from the pile, the heap leach pile is allowed to “rest,” which enables the geochemistry in the pile to equilibrate. At that point the heap leach pile may be subjected to another round of extraction by lixiviant, or it may be rinsed to flush out any remaining uranium that is in solution in the heap leach pile. After the rinsing, the pile is allowed to drain and a radon barrier required by 40 CFR 192.32 can be emplaced. We are proposing that the operational life of the heap leach pile be from the time that lixiviant is first placed on the heap leach pile until the time of the final rinse. We believe this incorporates a majority of the time when the heap leach pile is uncovered and when the ability for radon to be emitted is the greatest Again, though, we are asking for comment on these processes and procedures in order to make an informed decision for the final rule.

6. Prescriptive nature of requirement to maintain 1 meter of water within impoundments. We note that the requiremen t to maintain 1 meter of water within an impoundment containing byproduct does not provide operators much flexibility. For example, a licensee may use an impoundment in conjunction with a land application system. The land application system may only be able to operate in warmer weather, and may need to have an impoundment nearly empty to pr ovide sufficient disposal capacity for the time period during which the land application system is not capable of running. Additionally, if a liner is found to be leaking, the water level within the pond may need to be lowered to repair the liner system. As currently structured, this requirement does not give licensees any flexibility. We are also concerned that maintaining 1 meter of water over the liner may significantly increase the amount of li quids requiring disposal, especially at sites relying on some form of evaporation.

EPA Response: While the one meter liquid requirement may be prescriptive, we have been in contact with uranium recovery operators who have been making the claim that because of the liquids in the impoundments, there are no radon emissions. Therefore, EPA decided to formalize in a regulation what owners and operators have been claiming for years. Also, it is important to note that this is a proposed rule, and the Agency has asked for comment on this approach.

7. EPA inspection and oversight. As currently structured, it appears that uranium recovery facilities with impoundments would be subject to EPA inspection and oversight. It is not clear to us if this is a regulatory burden that is calculated (in terms of the burden imposed on licensees).

EPA Response : Under Subpart W, uranium recove ry facilities with impoundments have always been subject to EPA inspection and oversight. This cost has been included in the ICR for this rulemaking, and are also included in Table 1 of the preamble, roughly page 66.The comments below reflect interagency review of the draft rule under EOs 12866 and 13563. They are subject to further policy review.

Page 11 of 11 Specific Comments

1. Page 22, item A, describes the processes involved in a heap leach operation and identifies that potential liner systems could be construc ted of plastic, clay, or asphalt. Based on discussions with potential heap leach licensees, we understand that modern geosynthetic liners will likely be used. Corrected

.

2. Page 22, item B, describes liquid application practices that have previously been used at heap leach operations. Past practices likely did involve spraying acid on a heap leach pile, but potential operators have discussed using drip irrigation systems. For the rule language, it may be more accurate to say that acid would be applied by spraying, dripping, or flooding. Corrected

3. Page 22, items D and E, discusses using ion exchange as part of the uranium extraction process. It is our understanding that either ion exchange or solvent extraction techniques can be used to recover uranium at heap leach facilities. The decision to use one type or the other depends largely on the quality of the ore at a particular site. Corrected

4. Titan Uranium has been acquired by Energy Fuels; however, several sections of the proposed rule refer to potential future actions proposed by Titan Uranium. We recommend updating sections of the text to reflect that future actions for the Sheep Mountain site will be led by Energy Fuels. Examples of this issue that should be addressed can be found on pages 37 and 119. Corrected

5. Several dates or anticipated milestones have already passed. We recommend updating text to reflect current timelines or that anticipated activities have (or have not) occurred. Examples of this that should be addressed can be found on pages 37 and 41. Note that the anticipated applications table can be found at this location: http://www.nrc.gov/materials/uranium-recovery /license-apps/ur-projects-list-public.pdf.

Corrected

6. Page 90 has an incorrect Table reference. The text in the make-up water discussion

should refer to Table 3, not Table 1. Corrected.